U.S. patent application number 10/402823 was filed with the patent office on 2003-12-18 for multi-layer composites formed from compositions having improved adhesion, coating compositions, and methods related thereto.
Invention is credited to Anderson, Lawrence G., Burgman, John W., Hockswender, Thomas R., Morow, Karen A., Sadvary, Richard J., Simpson, Dennis A., Tyebjee, Shiryn.
Application Number | 20030232222 10/402823 |
Document ID | / |
Family ID | 25441692 |
Filed Date | 2003-12-18 |
United States Patent
Application |
20030232222 |
Kind Code |
A1 |
Anderson, Lawrence G. ; et
al. |
December 18, 2003 |
Multi-layer composites formed from compositions having improved
adhesion, coating compositions, and methods related thereto
Abstract
The present invention provides an improved multi-layer composite
of two or more polymeric layers at least one of which is formed
from a thermosetting composition. The composite includes at least a
first polymeric layer formed on a substrate and a second polymeric
layer over the first polymeric layer, wherein in the absence of a
boron-containing compound, the first and second polymeric layers
have poor interlayer adhesion. The improvement resides in the
inclusion of at least one boron-containing compound in one or both
of the first and second polymeric layers in an amount sufficient to
improve the interlayer adhesion between the first and second
polymeric layers. Also provided is an improved curable coating
composition used to form a multi-layer composite coating of two or
more cured coating layers, at least one of which is formed from the
thermosetting composition. Related methods and coated substrates
are also provided.
Inventors: |
Anderson, Lawrence G.;
(Pittsburgh, PA) ; Burgman, John W.; (Gibsonia,
PA) ; Morow, Karen A.; (Verona, PA) ; Sadvary,
Richard J.; (Pittsburgh, PA) ; Tyebjee, Shiryn;
(Allison Park, PA) ; Simpson, Dennis A.; (Wexford,
PA) ; Hockswender, Thomas R.; (Gibsonia, PA) |
Correspondence
Address: |
PPG INDUSTRIES, INC.
One PPG Place
Pittsburgh
PA
15272
US
|
Family ID: |
25441692 |
Appl. No.: |
10/402823 |
Filed: |
March 28, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10402823 |
Mar 28, 2003 |
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09919200 |
Jul 31, 2001 |
|
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6592999 |
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Current U.S.
Class: |
428/704 |
Current CPC
Class: |
C09D 7/60 20180101; C08K
3/38 20130101; Y10T 428/31786 20150401; B05D 7/574 20130101; Y10T
428/31511 20150401; Y10T 428/31663 20150401; C08K 5/55 20130101;
Y10T 428/31935 20150401; B05D 7/57 20130101; C08J 5/12 20130101;
Y10T 428/31725 20150401 |
Class at
Publication: |
428/704 |
International
Class: |
B32B 009/04 |
Claims
Therefore, we claim:
1. In a multi-layer composite of two or more polymeric layers at
least one of which is formed from a thermosetting composition, said
composite comprising at least a first polymeric layer formed on a
substrate and a second polymeric layer over at least a portion of
said first polymeric layer, wherein in the absence of a
boron-containing compound, said first polymeric layer and said
second polymeric layer have poor interlayer adhesion, the
improvement comprising the inclusion of at least one
boron-containing compound selected from boric acid, boric acid
equivalents, and mixtures thereof in one or both of said first and
second polymeric layers in an amount sufficient to improve the
interlayer adhesion of said first polymeric layer and said second
polymeric layer.
2. The composite of claim 1, wherein at least one boron-containing
compound is present in said first polymeric layer.
3. The composite of claim 1, wherein at least one boron-containing
compound is present in said second polymeric layer.
4. The composite of claim 1, wherein at least one boron-containing
compound is present in said first polymeric layer and in said
second polymeric layer.
5. The composite of claim 1, wherein said boron-containing compound
is selected from at least one of boric acid, boric acid ester,
metal borate, derivatives thereof and mixtures thereof.
6. The composite of claim 5, wherein said boron-containing compound
comprises boric acid.
7. The composite of claim 5, wherein said boron-containing compound
comprises a boric acid ester selected from at least one of
triisopropyl borate, trimethyl borate, triphenyl borate,
trimethoxyboroxine, polysiloxane borate, acrylic borate, and
mixtures thereof.
8. The composite of claim 5, wherein said boron-containing compound
comprises a boric acid ester derivative selected from at least one
of triethanolamineborate, mannitol borate, n-propranol amine
borate, trimetholpropane borate, glycerol borate, and mixtures
thereof.
9. The composite of claim 1, wherein both the first polymeric layer
and the second polymeric layer are formed from thermosetting
compositions.
10. The composite of claim 1, wherein said boron-containing
compound comprises the reaction product formed from the following
reactants: (A) at least one polysiloxane comprising at least one of
the following structural units (I):
R.sup.1.sub.nR.sup.2.sub.mSiO.sub.(4-n-m)/2 (I) wherein each
R.sup.1, which may be identical or different, represents H, OH, a
monovalent hydrocarbon group or a monovalent siloxane group; each
R.sup.2, which may be identical or different, represents a group
comprising one or more active hydrogens; and m and n each represent
a positive number fulfilling the requirements of 0<m<4;
0<n<4; and 2.ltoreq.(m+n)<4; and (B) a boron-containing
compound selected from at least one of boric acid, boric acid
equivalents, and mixtures thereof.
11. The composite of claim 10, wherein at least one R.sup.2
comprises OR', where R' is H or an alkyl group havin 1 to 20 carbon
atoms.
12. The composite of claim 10, wherein said polysiloxane comprises
one or more ungelled non-hydrolyzable organic polysiloxanes having
reactive functional groups, said polysiloxane having the following
structure (II) or (III): 4wherein: m has a value of at least 1; m'
ranges from 0 to 75; n ranges from 0 to 75; n' ranges from 0 to 75;
each R, which may be identical or different, is selected from H,
OH, monovalent hydrocarbon groups, monovalent siloxane groups, and
mixtures of any of the foregoing; and R.sup.a comprises the
following structure (IV): --R.sup.3X (IV) wherein --R.sup.3 is
selected from an alkylene group, an oxyalkylene group, an alkylene
aryl group, an alkenylene group, an oxyalkenylene group, and an
alkenylene aryl group; and; and R.sup.a comprises the following
structure (IV): R.sup.3--X (IV) wherein R.sup.3 is alkenylene,
alkylene, oxyalkylene, alkylene aryl or alkenylene; and X
represents a group which comprises at least one reactive functional
group selected from at least one of a hydroxyl group, a carboxyl
group, a primary amine group, a secondary amine group, an amide
group, a carbamate group, a urea group, an anhydride group, a
hydroxy alkylamide group, and an epoxy group.
13. The composite of claim 12, wherein the polysiloxane is the
reaction product of the following reactants: (A) at least one
silicon hydride-containing polysiloxane having the following
structure (V): 5wherein the R groups are selected from H, OH,
monovalent hydrocarbon groups, siloxane groups and mixtures
thereof, wherein at least one of the groups represented by R is H,
and n' ranges from 0 to 100, such that the mole percent of
hydrogen-bonded silicon atoms to non-hydrogen-bonded silicon atoms
ranges from 10 to 100 percent; and (B) one or more hydroxyl
functional materials comprising at least one primary hydroxyl group
and at least one unsaturated bond capable of undergoing
hydrosilylation reaction.
14. The composite of claim 13, wherein reactant (B) is a hydroxyl
functional group-containing allyl ether selected from
trimethylolpropane monoallyl ether, pentaerythritol monoallyl
ether, trimethylolpropane diallyl ether and mixtures thereof; or an
allyl alcohol.
15. The composite of claim 10, wherein the first polymeric layer is
formed from a thermosetting composition comprising a
boron-containing compound present in said thermosetting composition
in an amount sufficient to provide an amount of boron ranging from
0.001 to 5 percent by weight, based on weight of total resin solids
present in the thermosetting composition.
16. The composite of claim 1, wherein one or both of said first
polymeric layer and said second polymeric layer comprises a cured
layer formed from a thermosetting composition comprising: (A) at
least one film-forming polymer having reactive functional groups;
(B) at least one curing agent having functional groups reactive
with the functional groups of (A); and (C) at least one
boron-containing compound selected from at least one of boric acid,
boric acid equivalents, and mixtures thereof.
17. The composite of claim 16, wherein the film-forming polymer (A)
comprises at least one polymer selected from an acrylic polymer, a
polyester polymer, a polyurethane polymer, a polyether polymer, a
silicon-based polymer, and mixtures thereof.
18. The composite of claim 16, wherein the film-forming polymer (A)
comprises an acrylic polymer, a polyester polymer, and mixtures
thereof.
19. The composite of claim 16, wherein the film-forming polymer (A)
comprises an acrylic polymer.
20. The composite of claim 16, wherein the film-forming polymer (A)
comprises functional groups selected from a hydroxyl group, a
carboxyl group, an isocyanate group, a blocked polyisocyanate
group, a primary amine group, a secondary amine group, an amide
group, a carbamate group, a urea group, a urethane group, a vinyl
group, an unsaturated ester group, a maleimide group, a fumarate
group, an anhydride group, a hydroxy alkylamide group, and an epoxy
group.
21. The composite of claim 16, wherein the film-forming polymer
comprises functional groups selected from hydroxyl groups,
carbamate groups and mixtures thereof.
22. The composite of claim 19, wherein the film-forming polymer (A)
comprises the residue of a beta-hydroxy group-containing monomer
selected from at least one of (A) the reaction product of an
ethylenically unsaturated acid functional monomer and an epoxy
functional compound having no ethylenic unsaturation; and (B) the
reaction product of an ethylenically unsaturated, epoxy functional
monomer and a saturated carboxylic acid.
23. The composite of claim 16, wherein the curing agent (B)
comprises aminoplast resins, polyisocyanates, blocked
polyisocyanates, polycarboxylic acids, polyanhydrides,
polyepoxides, polyamines, polyols, and mixtures thereof.
24. The composite of claim 21, wherein the curing agent (B) is
selected from aminoplast resins, polyisocyanates, blocked
isocyanates and mixtures thereof.
25. The composite of claim 22, wherein the curing agent (B) is
selected from aminoplast resins, polyisocyanates, blocked
polyisocyanates and mixtures thereof.
26. The composite of claim 22, wherein the curing agent (B)
comprises at least one aminoplast resin and at least one blocked
isocyanate compound comprising a tricarbamoyl triazine
compound.
27. The composite of claim 16, wherein both the first polymeric
layer and the second polymeric layer are formed from a
thermosetting composition.
28. The composite of claim 27, wherein the first polymeric layer is
formed from a thermosetting composition comprising: (A) at least
one film-forming polymer having reactive functional groups; (B) at
least one curing agent having functional groups reactive with the
functional groups of (A); and (C) at least one boron-containing
compound selected from boric acid, boric acid equivalents, and
mixtures thereof.
29. The composite of claim 27, wherein the first polymeric layer is
formed from a thermosetting composition comprising: (A) at least
one film-forming acrylic polymer comprising functional groups
selected from hydroxyl groups, carbamate groups and mixtures
thereof; (B) at least one curing agent selected from aminoplast
resins, polyisocyanates, blocked polyisocyanates and mixtures
thereof; and (C) at least one boron-containing compound selected
from boric acid, boric acid equivalents, and mixtures thereof.
30. The composite of claim 27, wherein the boron-containing
compound (C) is present in the thermosetting composition in an
amount sufficient to provide an amount of boron ranging from 0.001
to 5 percent by weight based on total resin solids present in the
thermosetting composition.
31. The composite of claim 29, wherein the curing agent (B)
comprises an aminoplast resin, and a blocked isocyanate comprising
a tricarbamoyl triazine compound.
32. The composite of claim 27, wherein the boron-containing
compound (C) comprises a reaction product formed from the following
reactants: (A) at least one polysiloxane comprising at least one of
the following structural units (I): R.sup.1.sub.nR.sup.2
.sub.mSiO.sub.(4-n-m)/2 (I) wherein each R.sup.1 is independently
selected from H, a monovalent hydrocarbon group or a siloxane
group; each R.sup.2 independently is a group comprising OR', where
R' is H or an alkyl group having 1 to 20 carbon atoms; and m and n
each represent a positive number fulfilling the requirements of
0<m<4; 0<n<4; and 2.ltoreq.(m+n)<4; and (B) a
boron-containing compound comprising at least one of boric acid,
boric acid equivalents, and mixtures thereof.
33. The composite of claim 32, wherein the boron-containing
compound (C) comprises boric acid and/or boric acid ester.
34. The composite of claim 32, wherein the boron-containing
compound (C) is present in the thermosetting composition in an
amount sufficient to provide an amount of boron ranging from 0.001
to 5 weight percent based on weight of total resin solids present
in the thermosetting composition.
35. The composite of claim 27, wherein said first thermosetting
composition comprises a base coating composition and second
thermosetting composition comprises a top coating composition.
36. The composite of claim 35, wherein said first thermosetting
composition comprises a substantially pigment-free base coating
composition, and said second thermosetting composition comprises a
substantially pigment-free top coating composition.
37. The composite of claim 35, wherein said first thermosetting
composition comprises a pigment-containing base coating
composition, and said second thermosetting composition comprises a
pigment-containing top coating composition.
38. The composite of claim 35, wherein said first thermosetting
composition comprises a pigment-containing base coating
composition, and said second thermosetting composition comprises a
substantially pigment-free coating composition.
39. The composite of claim 35, wherein said first thermosetting
composition comprises a substantially pigment-free base coating
composition, and said second thermosetting composition comprises a
pigment-containing top coating composition.
40. The composite of claim 36, wherein said second thermosetting
composition comprises an adhesive composition.
41. The composite of claim 1, wherein said first polymeric layer is
formed on a metallic substrate.
42. The composite of claim 1, wherein said first polymeric layer is
formed on an elastomeric substrate.
43. The composite of claim 1, wherein said first polymeric layer is
formed on a substrate comprising a substrate and one or more
polymeric layers.
44. The composite of claim 43, wherein said substrate comprises a
substrate and one or more polymeric layers formed from one or more
thermosetting film-forming compositions.
45. In a curable coating composition used to form a multi-layer
composite coating comprising two or more cured coating layers, said
multi-layer composite coating comprising at least a first coating
layer formed on a substrate and a second coating layer over at
least a portion of said first polymeric layer, wherein one or both
of said first coating layer and said second coating layer are
formed from said curable coating composition, and wherein in the
absence of a boron-containing compound, said first coating layer
and said second coating layer have poor interlayer adhesion, the
improvement comprising the inclusion in said curable coating
composition of a boron-containing compound selected from at least
one of boric acid, boric acid equivalents, and mixtures thereof in
an amount sufficient to improve the interlayer adhesion between
said first coating layer and said second coating layer.
46. The coating composition of claim 45, wherein at least one
boron-containing compound is present in said first coating
layer.
47. The coating composition of claim 45, wherein at least one
boron-containing compound is present in said second coating
layer.
48. The coating composition of claim 45, wherein at least one
boron-containing compound is present in said first coating layer
and in said second coating layer.
49. The coating composition of claim 45, wherein said
boron-containing compound is selected from at least one of boric
acid and boric acid ester.
50. The coating composition of claim 45, wherein both the first
coating layer and the second coating layer are formed from curable
coating compositions.
51. The coating composition of claim 45, wherein said
boron-containing compound comprises the reaction product of the
following reactants: (A) at least one polysiloxane comprising at
least one of the following structural units (I):
R.sup.1.sub.nR.sup.2 .sub.mSiO.sub.(4-n-m)/2 (I) wherein each
R.sup.1, which may be identical or different, represents H, OH, a
monovalent hydrocarbon group or a monovalent siloxane group; each
R.sup.2, which may be identical or different, represents a group
comprising one or more active hydrogens; and m and n each represent
a positive number fulfilling the requirements of 0<m<4;
0<n<4; and 2.ltoreq.(m+n)<4; and (B) at least one
boron-containing compound selected from at least one of boric acid,
boric acid equivalents, and mixtures thereof.
52. The coating composition of claim 51, wherein at least one
R.sup.2 comprises OR', where R' represents H or an alkyl group
having 1 to 20 carbon atoms.
53. The coating composition of claim 51, wherein said polysiloxane
(A) comprises one or more ungelled, organic polysiloxanes having
reactive functional groups, said polysiloxane having the following
structure (II) or (III): 6where m has a value of at least 1; m'
ranges from 0 to 75; n ranges from 0 to 75; n' ranges from Q to 75;
each R, which may be identical or different, is selected from H,
OH, monovalent hydrocarbon groups, monovalent siloxane groups, and
mixtures of any of the foregoing; and R.sup.a comprises the
following structure (IV): --R.sup.3--X (IV) wherein --R.sup.3 is
selected from an alkylene group, an oxyalkylene group, an alkylene
aryl group, an alkenylene group, an oxyalkenylene group, and an
alkenylene aryl group; and X represents a group which comprises at
least one reactive functional group selected from selected from at
least one of a hydroxyl group, a carboxyl group, a primary amine
group, a secondary amine group, an amide group, a carbamate group,
a urea group, an anhydride group, a hydroxy alkylamide group, and
an epoxy group.
54. The coating composition of claim 53, wherein the polysiloxane
comprises the reaction product of the following reactants: (A) at
least one silicon hydride-containing polysiloxane having the
following structure (V): 7wherein the R groups are selected from H,
OH, monovalent hydrocarbon groups, siloxane groups and mixtures
thereof, wherein at least one of the groups represented by R is H,
and n' ranges from 0 to 100, such that the mole percent of
hydrogen-bonded silicon atoms to non-hydrogen-bonded silicon atoms
ranges from 10 to 100 percent; and (B) one or more hydroxyl
functional materials comprising at least one hydroxyl group and at
least one unsaturated bond capable of undergoing hydrosilylation
reaction.
55. The coating composition of claim 54, wherein reactant (B)
comprises at least one of an allyl alcohol, and a hydroxyl
functional group-containing allyl ether selected format least one
of trimethylolpropane monoallyl ether, pentaerythritol monoallyl
ether, trimethylolpropane diallyl ether and mixtures thereof.
56. The coating composition of claim 45, comprising a
boron-containing compound present in an amount sufficient to
provide an amount of boron in at least one of said cured coating
layers ranging from 0.001 to 5 percent by weight, based on the
weight of total resin solids present in said curable coating
composition.
57. The coating composition of claim 45, wherein one or both of
said first coating layer and said second coating layer comprises a
cured coating layer formed from a curable coating composition
comprising: (A) at least one film-forming polymer having reactive
functional groups; (B) at least one curing agent having functional
groups reactive with the functional groups of (A); and (C) at least
one boron-containing compound selected from at least one of boric
acid, boric acid equivalents, and mixtures thereof.
58. The coating composition of claim 57, wherein the film-forming
polymer (A) comprises a polymer selected from an acrylic polymer, a
polyester polymer, a polyurethane polymer, a polyether polymers a
silicon-based polymer, and mixtures thereof.
59. The coating composition of claim 57, wherein the film-forming
polymer comprises an acrylic polymer, a polyester polymer and
mixtures thereof.
60. The coating composition of claim 57 wherein the film-forming
polymer comprises an acrylic polymer.
61. The coating composition of claim 57, wherein the film-forming
polymer comprises functional groups selected from a hydroxyl group,
a carboxyl group, an isocyanate group, a blocked isocyanate group,
a primary amine group, a secondary amine group, an amide group, a
carbamate group, a urea group, a urethane group, a vinyl group, an
unsaturated ester group, a maleimide group, a fumarate group, an
anhydride group, a hydroxy alkylamide group, and an epoxy
group.
62. The coating composition of claim 57, wherein the film-forming
polymer comprises functional groups selected from hydroxyl groups,
carbamate groups and mixtures thereof.
63. The coating composition of claim 60, wherein the film-forming
polymer (A) comprises the residue of a beta-hydroxy
group-containing monomer selected from at least one of (A) the
reaction product of an ethylenically unsaturated acid functional
monomer and an epoxy functional compound having no ethylenic
unsaturation; and (B) the reaction product of an ethylenically
unsaturated, epoxy functional monomer and a saturated carboxylic
acid.
64. The coating composition of claim 57, wherein the curing agent
(B) comprises aminoplast resins, polyisocyanates, blocked
isocyanates, polycarboxylic acids, polyanhydrides, polyepoxides,
polyamines, polyols, and mixtures thereof.
65. The composite of claim 62, wherein the curing agent (B) is
selected from aminoplast resins, polyisocyanates, blocked
polyisocyanates and mixtures thereof.
66. The coating composition of claim 63, wherein the curing agent
(B) is selected from aminoplast resins, polyisocyanates, blocked
polyisocyanates and mixtures thereof.
67. The coating composition of claim 66, wherein the curing agent
(B) comprises at least one aminoplast resin and at least one
blocked polyisocyanate comprising a tricarbamoyl triazine
compound.
68. The coating composition of claim 57, wherein the first coating
layer is formed from a curable coating composition comprising: (A)
at least one film-forming polymer having reactive functional
groups; (B) at least one curing agent having functional groups
reactive with the functional groups of (A); and (C) at least one
boron-containing compound selected from boric acid, boric acid
equivalents, and mixtures thereof.
69. The coating composition of claim 57, wherein the first coating
layer is formed from a curable coating composition comprising: (A)
at least one film-forming acrylic polymer comprising functional
groups selected from hydroxyl groups, carbamate groups and mixtures
thereof; (B) at least one curing agent selected from aminoplast
resins, polyisocyanates, blocked polyisocyanates and mixtures
thereof; and (C) at least one boron-containing compound selected
from boric acid, boric acidequivalents, and mixtures thereof.
70. The coating composition of claim 68, wherein the
boron-containing compound (C) is present in the curable coating
composition in an amount sufficient to provide an amount of boron
ranging from 0.001 to 5 percent by weight based on weight of total
resin solids present in the curable coating composition.
71. The coating composition of claim 69, wherein the curing agent
(B) comprises an aminoplast resin and a blocked polyisocyanate
comprising a tricarbamoyl triazine compound.
72. The coating composition of claim 67, wherein the
boron-containing compound (C) comprises a reaction product formed
from the following reactants: (A) at least one polysiloxane
comprising having at least one of the following structural units
(I): R.sup.1.sub.nR.sup.2.sub.mSiO.sub.- (4-n-m)/2 (I) wherein each
R.sup.1 independently is selected from H, a monovalent hydrocarbon
group or a siloxane group; each R.sup.2 is independently a group
comprising OR', where R' is H or an alkyl group having 1 to 20
carbon atoms; and m and n each represent a positive number
fulfilling the requirements of 0<m<4; 0<n<4; and
2.ltoreq.(m+n)<4; and (B) at least one boron-containing compound
comprising at least one of boric acid, boric acidequivalents, and
mixtures thereof.
73. The coating composition of claim 72, wherein the
boron-containing compound (C) is present in the curable coating
composition in an amount sufficient to provide an amount of boron
ranging from 0.001 to 5 weight percent, based on weight of total
resin solids present in the coating composition.
74. The coating composition of claim 68, wherein said first curable
coating composition comprises a base coating composition and said
second curable coating composition comprises a top coating
composition.
75. The coating composition of claim 68, wherein said first curable
coating composition comprises a substantially pigment-free base
coating composition, and said second curable coating composition
comprises a substantially pigment-free top coating composition.
76. The coating composition of claim 68, wherein said first curable
coating composition comprises a pigment-containing base coating
composition, and said second curable coating composition comprises
a pigment-containing top coating composition.
77. The coating composition of claim 68, wherein said first curable
coating composition comprises a pigment-containing base coating
composition, and said second coating composition comprises a
substantially pigment-free coating composition.
78. The coating composition of claim 68, wherein said first curable
coating composition comprises a substantially pigment-free base
coating composition, and said second curable coating composition
comprises a pigment-containing top coating composition.
79. The coating composition of claim 78, wherein said second
curable coating composition comprises an adhesive composition.
80. The coating composition of claim 45, wherein said first
polymeric layer is formed on a metallic substrate.
81. The coating composition of claim 45, wherein said first
polymeric layer is formed on an elastomeric substrate.
82. The coating composition of claim 45, wherein said first
polymeric layer is formed on a substrate comprising a substrate and
one or more polymeric layers.
83. The coating composition of claim 45, wherein said substrate
comprises a substrate and one or more polymeric layers formed from
one or more thermosetting film-forming compositions.
84. A method for improving the intercoat adhesion of a multi-layer
composite comprising two or more polymeric layers, at least one of
which is formed from a thermosetting composition, said composite
comprising at least a first polymeric layer formed on at least a
portion of a substrate, and a second polymeric layer formed over at
least a portion of said first polymeric layer, wherein in the
absence of a boron-containing compound, said first polymeric layer
and said second polymeric layer have poor interlayer adhesion, the
improvement comprising the inclusion of at least one
boron-containing compound selected from boric acid, boric acid
equivalents, and mixtures thereof in one or both of said first and
second polymeric layers in an amount sufficient to improve the
interlayer adhesion of said first polymeric layer and said second
polymeric layer.
85. The method of claim 84, wherein at least one boron-containing
compound is present in said first polymeric layer.
86. The method of claim 84, wherein at least one boron-containing
compound is present in said second polymeric layer.
87. The method of claim 84, wherein at least one boron-containing
compound is present in said first polymeric layer and in said
second polymeric layer.
88. The method of claim 84, wherein said boron-containing compound
is selected from at least one of boric acid, borate ester,
.backslash. and mixtures thereof.
89. The method of claim 88, wherein said boron-containing compound
comprises boric acid.
90. The method of claim 88, wherein said boron-containing compound
comprises a borate ester selected from at least one of acrylic
borate ester, polysiloxane borate ester, polyester borate ester,
polyurathane borate ester, and mixtures thereof.
91. The method of claim 88, wherein said boron-containing compound
comprises a borborate ester selected from at least one of
triethanolamineborate, triisopropyl borate, trimethyl borate,
triphenyl borate trimethoxyboroxine triethanolamine borate;
mannitol borate; n-propranol amine borate, trimetholpropane borate,
glycerol borate and mixtures thereof.
92. The method of claim 84, wherein both the first polymeric layer
and the second polymeric layer are formed from thermosetting
compositions.
93. The method of claim 84, wherein said boron-containing compound
comprises the reaction product formed from the following reactants:
(A) at least one polysiloxane comprising at least one of the
following structural units (I): R.sup.1.sub.nR.sup.2
.sub.mSiO.sub.(4-n-m)/2 (I) wherein each R.sup.1 is independently
selected from a monovalent hydrocarbon group or a siloxane group;
each R.sup.2 independently is a group comprising OR', where R' is H
or an alkyl group having 1 to 20 carbon atoms; and m and n each
represent a positive number fulfilling the requirements of
0<m<4; 0<n<4; and 2.ltoreq.(m+n)<4; and (B) at least
one boron-containing compound selected from at least one of boric
acid, boric acidequivalents, and mixtures thereof.
94. The method of claim 93, wherein at least one R.sup.2 comprises
OH.
95. The method of claim 93, wherein said polysiloxane comprises one
or more ungelled, organic polysiloxanes having reactive functional
groups, said polysiloxane having the following structure (II) or
(III): 8where m has a value of at least 1; m' ranges from 0 to 75;
n ranges from 0 to 75; n' ranges from 0 to 75; each R, which may be
identical or different, is selected from H, OH, monovalent
hydrocarbon groups, monovalent siloxane groups, and mixtures of any
of the foregoing; and R.sup.a comprises the following structure
(IV): --R.sup.3--X (IV) wherein --R.sup.3 is selected from an
alkylene group, an oxyalkylene group, an alkylene aryl group, an
alkenylene group, an oxyalkenylene group, and an alkenylene aryl
group; and X represents a group which comprises at least one
reactive functional group selected from selected from at least one
of a hydroxyl group, a carboxyl group, a primary amine group, a
secondary amine group, an amide group, a carbamate group, a urea
group, an anhydride group, a hydroxy alkylamide group, and an epoxy
group.
96. The method of claim 95, wherein the polysiloxane is a reaction
product formed from the following reactants: (A) a silicon
hydride-containing polysiloxane having the following structure (V):
9wherein the R groups are selected from H, OH, monovalent
hydrocarbon groups, siloxane groups and mixtures thereof, wherein
at least one of the groups represented by R is H, and n' ranges
from 0 to 100, such that the mole percent of hydrogen-bonded
silicon atoms to non-hydrogen-bonded silicon atoms ranges from 10
to 100 percent; and (B) one or more hydroxyl functional materials
comprising at least one primary hydroxyl group and at least one
unsaturated bond capable of undergoing hydrosilylation
reaction.
97. The method of claim 96, wherein reactant (B) is a hydroxyl
functional group-containing allyl ether selected from at least one
of trimethylolpropane monoallyl ether, pentaerythritol monoallyl
ether, trimethylolpropane diallyl ether and mixtures thereof; or an
allyl alcohol.
98. The method of claim 84, wherein the first polymeric layer is
formed from a thermosetting composition comprising a
boron-containing compound present in said thermosetting composition
in an amount sufficient to provide an amount of boron ranging from
0.001 to 5 percent by weight, based on weight of total resin solids
present in the thermosetting composition.
99. The method of claim 84, wherein one or both of said first
polymeric layer and said second polymeric layer comprises a cured
layer formed from a thermosetting composition comprising: (A) at
least one film-forming polymer having reactive functional groups;
and (B) at least one curing agent having functional groups reactive
with the functional groups of (A); and (C) at least one
boron-containing compound selected from at least one of boric acid,
boric acidequivalents, and mixtures thereof.
100. The composite of claim 99, wherein the film-forming polymer
(A) comprises a polymer selected from acrylic polymers, polyester
polymers, polyurethane polymer, polyether polymers, silicon-based
polymers, and mixtures thereof.
101. The method of claim 99, wherein the film-forming polymer (A)
comprises an acrylic polymer, a polyester polymer and mixtures
thereof.
102. The method of claim 99, wherein the film-forming polymer (A)
comprises an acrylic polymer.
103. The method of claim 99, wherein the film-forming polymer (A)
comprises functional groups selected from at least one of a
hydroxyl group, a carboxyl group, an isocyanate group, a blocked
polyisocyanate group, a primary amine group, a secondary amine
group, an amide group, a carbamate group, a urea group, a urethane
group, a vinyl group, an unsaturated ester group, a maleimide
group, a fumarate group, an anhydride group, a hydroxy alkylamide
group, and an epoxy group.
104. The method of claim 103, wherein the film-forming polymer (A)
comprises functional groups selected from hydroxyl groups,
carbamate groups and mixtures thereof.
105. The method of claim 102, wherein the film-forming polymer (A)
comprises the residue of a beta-hydroxy group-containing monomer
selected from at least one of (A) the reaction product of an
ethylenically unsaturated acid functional monomer and an epoxy
functional compound having no ethylenic unsaturation; and (B) the
reaction product of an ethylenically unsaturated, epoxy functional
monomer and a saturated carboxylic acid.
106. The method of claim 99, wherein the curing agent (B) comprises
aminoplast resins, polyisocyanates, blocked isocyanates,
polycarboxylic acids, polyanhydrides, polyepoxides, polyamines,
polyols, and mixtures thereof.
107. The method of claim 104, wherein the curing agent (B) is
selected from aminoplast resins, polyisocyanates, blocked
isocyanates and mixtures thereof.
108. The method of claim 105, wherein the curing agent (B)
comprises at least one aminoplast resin and at least one blocked
isocyanate comprising a tricarbamoyl triazine compound.
109. The method of claim 99, wherein both the first polymeric layer
and the second polymeric layer are formed from a thermosetting
composition.
110. The method of claim 109, wherein the first polymeric layer is
formed from a thermosetting composition comprising: (A) at least
one film-forming polymer having reactive functional groups; (B) at
least one curing agent having functional groups reactive with the
functional groups of (A); and (C) at least one boron-containing
compound selected from boric acid, boric acidequivalents, and
mixtures thereof.
111. The method of claim 110, wherein the first polymeric layer is
formed from a thermosetting composition comprising: (A) at least
one film-forming acrylic polymer comprising functional groups
selected from hydroxyl groups, carbamate groups and mixtures
thereof; (B) at least one curing agent selected from aminoplast
resins, polyisocyanates, blocked isocyanates and mixtures thereof;
and (C) at least one boron-containing compound selected from boric
acid, boric acidequivalents, and mixtures thereof.
112. The method of claim 110, wherein the boron-containing compound
(C) is present in the thermosetting composition in an amount
sufficient to provide an amount of boron ranging from 0.001 to 5
percent by weight based on total resin solids present in the
thermosetting composition.
113. The method of claim 111, wherein the curing agent (B)
comprises an aminoplast resin and a blocked isocyanate comprising a
tricarbamoyl triazine compound.
114. The method of claim 111, wherein the boron-containing compound
(C) comprises the reaction product formed from the following
reactants: (A) at least one polysiloxane comprising at least one of
the following structural units (I):
R.sup.1.sub.nR.sup.2.sub.mSiO.sub.(4-n-m)/2 (I) wherein each
R.sup.1 is independently selected from a monovalent hydrocarbon
group or a siloxane group; each R.sup.2 independently is a group
comprising OR', where R' is H or an alkyl group having 1 to 20
carbon atoms; and m and n each represent a positive number
fulfilling the requirements of 0<m<4; 0<n<4; and
2.ltoreq.(m+n)<4; and (B) a boron-containing compound comprising
at least one of boric acid, boric acidequivalents, and mixtures
thereof.
115. The method of claim 114, wherein the boron-containing compound
(C) comprises boric acid and/or boric acid ester.
116. The method of claim 114, wherein the boron-containing compound
(C) is present in the thermosetting composition in an amount
sufficient to provide an amount of boron ranging from 0.001 to 5
weight percent based on weight of total resin solids present in the
thermosetting composition.
117. The method of claim 92, wherein said first thermosetting
composition comprises a base coating composition and second
thermosetting composition comprises a top coating composition.
118. The composite of claim 92, wherein said first thermosetting
composition comprises a substantially pigment-free base coating
composition, and said second thermosetting composition comprises a
substantially pigment-free top coating composition.
119. The method of claim 92, wherein said first thermosetting
composition comprises a pigment-containing base coating
composition, and said second thermosetting composition comprises a
pigment-containing top coating composition.
120. The method of claim 92, wherein said first thermosetting
composition comprises a pigment-containing base coating
composition, and said second thermosetting composition comprises a
substantially pigment-free coating composition.
121. The method of claim 92, wherein said first thermosetting
composition comprises a substantially pigment-free base coating
composition, and said second thermosetting composition comprises a
pigment-containing top coating composition.
122. The method of claim 121, wherein said second thermosetting
composition comprises an adhesive composition.
123. A curable coating composition formed from components
comprising: (A) at least one film-forming polymer comprising at
least one reactive functional group; (B) at least one reactant
comprising at least one functional group that is reactive with the
reactive functional group of the polymer (A); and (C) at least one
compound selected from borates, aluminates, titanates, zirconates,
silicates, siloxanes, silanes, and mixtures thereof, wherein each
component is different.
124. A coating composition according to claim 123, wherein the
compound (c) comprises at least one of a borate and an
aluminate.
125. A coating composition according to claim 124, wherein the
compound (c) comprises aluminum is propoxide.
126. A substrate comprising a substrate and a coating composition
according to claim 45 over at least a portion of the substrate.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] Reference is made to related U.S. patent application Ser.
Nos. ______, ______, ______ and ______, filed concurrently
herewith.
FIELD OF THE INVENTION
[0002] The present invention relates to multi-layer composites of
two or more polymeric layers, at least one of which is formed from
a thermosetting composition. The composite comprising at least a
first polymeric layer formed on a substrate and a second polymeric
formed over at least a portion of the first polymeric layer,
wherein in the absence of an adhesion promoting composition, the
first polymeric layer and the second polymeric layer have poor
interlayer adhesion. The present invention also relates to curable
coating compositions used to form multi-layer composites, to
methods for improving the interlayer adhesion of such multi-layer
composites and to coated substrates.
BACKGROUND OF THE INVENTION
[0003] Color-plus-clear coating systems involving the application
of a colored or pigmented basecoat to a substrate followed by
application of a transparent or clearcoat over the basecoat have
become increasingly popular as original finishes for a number of
consumer products including, for example, automotive vehicles. The
color-plus-clearcoating systems have outstanding appearance
properties such as gloss and distinctness of image, due in large
part to the clearcoat. Such color-plus-clearcoating systems have
become popular for use with automotive vehicles, aerospace
applications, floor coverings such as ceramic tiles and wood
flooring, packaging coatings and the like.
[0004] Topcoat coating compositions, particularly those used to
form the transparent clearcoat in color-plus-clearcoating systems
for automotive applications, are subject to defects that occur
during the assembly process as well as damage from numerous
environmental elements. Such defects during the assembly process
include paint defects in the application or curing of the basecoat
or the clearcoat. Damaging environmental elements include acidic
precipitation, exposure to ultraviolet radiation from sunlight,
high relative humidity and high temperatures, defects due to
contact with objects causing scratching of the coated surface, and
defects due to impact with small, hard objects resulting in
chipping of the coating surface.
[0005] Further, elastomeric automotive parts and accessories, for
example, elastomeric bumpers and body side moldings, are typically
coated "off site" and shipped to automobile assembly plants. The
coating compositions applied to such elastomeric substrates are
typically formulated to be very flexible so the coating can bend or
flex with the substrate without cracking. To achieve the requisite
flexibility, coating compositions for use on elastomeric substrates
often are formulated to produce coatings with lower crosslink
densities or to include flexibilizing adjuvants which act to lower
the overall film glass transition temperature (Tg). While
acceptable flexibility properties can be achieved with these
formulating techniques, they also can result in softer films that
are susceptible to scratching. Consequently, great expense and care
must be taken to package the coated parts to prevent scratching of
the coated surfaces during shipping to automobile assembly
plants.
[0006] U.S. Pat. No. 6,235,858 B1 discloses carbamate and/or urea
functional polymers for use in coating compositions, especially
clear coating compositions for color-plus-clear coating systems.
Such polymers provide coatings with good resistance to damage
caused by acidic precipitation.
[0007] U.S. Pat. No. 5,853,809 discloses clearcoats in
color-plus-clear systems which have improved scratch resistance due
to the inclusion in the coating composition of inorganic particles
such as colloidal silicas which have been surface modified with a
reactive coupling agent via covalent bonding.
[0008] A number of patents disclose the use of a surface active
material, for example, a polysiloxane, in coating compositions to
improve mar resistance of the cured coatings. U.S. Pat. Nos.
5,939,491 and 6,225,434B1 disclose coating compositions comprising
organic polysiloxanes having reactive functional groups. These
polysiloxanes provide coatings with improved mar and scratch
resistance.
[0009] A number of patents disclose the use of boric acid in
polymeric compositions. For example, U.S. Pat. Nos. 5,951,747 and
6,059,867 discloses the use of boric acid and borates in
conjunction with a succinate in non-chromate, corrosion-inhibiting
coating compositions for improved adhesion to metallic surfaces.
Such compositions further include inhibitors such as phosphates,
phosphosilicates, silicates, titanates, and zinc salts. U.S. Pat.
No. 4,832,990 discloses a process for improving adhesion of
polyolefins to metal substrates comprising mechanical cleaning of
the metal surface, treating the metal surface with a water-alcohol
solution containing an alkoxysilane and boric acid, thermally
treating the acid treated substrate, and subsequently treating the
substrate with a polyolefin-based composition comprising zeolites
and carbon black pigment. U.S. Pat. No. 5,073,455 discloses a
thermoplastic laminated film which has improved adhesion to
hydrophilic polymers, hydrophobic polymers and inorganic
substances. The film comprise a base film of thermoplastic resin
and a layer formed on the base film comprising a composition of one
or more of water-soluble resins, water emulsified resins and
water-dispersible resins, and an organic boron polymer or a mixture
composed of an organic boron polymer and vinyl alcohol.
[0010] Other multi-layer composite coatings are commonplace in
modern coating lines. For example, a typical automotive coating
system can include the sequential application of an
electrodeposition primer, a primer-surfacer, a color enhancing base
coat, and a transparent top coat. In some instances, the
electrodeposition primer is applied over a mill-applied weldable,
thermosetting coating which has been applied to the coiled steel
metal substrate from which the automobile body (or body parts, such
as fenders, doors and-hoods) has been formed. Also, adhesive
coatings, for example, windshield adhesives, trim and molding
adhesives and structural adhesives are sometimes applied to the
cured top coats where necessary. Due to these multi-layer composite
coating processes, it is necessary that the previously applied
coating layer have excellent intercoat or interlayer adhesion to
the subsequently applied coating layer(s).
[0011] Although the aforementioned coating compositions exhibit
improvements for acid etch resistance and mar and scratch
resistance, such compositions may not be readily recoatable. That
is, when a subsequent coating is applied to the cured mar and
scratch resistant coating composition, the intercoat adhesion
between the cured coating and the subsequently applied coating can
be quite poor.
[0012] For example, as mentioned above, on most vehicle coating
lines the vehicle body is first given a corrosion inhibitive
electrodepositable primer coating commonly formed from a cationic
electrodepositable coating composition. This electrodeposition
primer is fully cured and, a primer-surfacer is typically applied
to the cured electrodeposition primer. The primer-surfacer serves
to enhance chip resistance of subsequently applied top coatings as
well as to ensure good appearance of the top coatings. The
electrodepositable primer must have excellent interlayer, i.e.,
intercoat, adhesion to the subsequently applied primer-surfacer
coating. The top coats, which can include a monocoats as well as a
color-plus-clear coating system, are then applied to the cured
primer-surfacer coating. While most top coats have excellent
intercoat adhesion to the primer-surfacer coating, some top coating
compositions inherently may exhibit intercoat adhesion problems
with some primer-surfacer coatings.
[0013] Also, due to the resultant cost-savings, there is recent
interest in the automotive coatings market in eliminating the
primer-surfacer step altogether. That is, the top coats can be
directly applied to the cured electrodeposition primer. In such
modified coating processes, the electrodeposition primer is
required to meet stringent durability and appearance
specifications. Moreover, the cured electrodepositable primer must
have excellent intercoat adhesion to the subsequently applied top
coats (either monocoats or color coats of a color-plus-clear
system).
[0014] On commercial automobile coating lines during application of
the coating system, certain portions of the line can experience
occasional process problems, for example, clearcoat applicator
malfunctions, or curing oven faults where temperatures are out of
specification. While the color coat typically is "flash cured" to
drive off solvent, but not fully cure the coating, once the clear
coating has been applied, the color-plus-clear coating system
typically is given a full cure (e.g., 250.degree. F. for 20
minutes) to simultaneously cure both the base coat and the top
coat. In instances where the clear coat application system is
malfunctioning, the auto body with the applied color coat will
continue through the clear coat applicator station and into the
clear coat curing oven, thereby fully curing the color coat. If
this occurs, some automobile manufacturers elect to reapply the
color coat over the fully cured color coat prior to application of
the clearcoat. In such situations, the fully cured color coat can
have poor intercoat adhesion with the subsequently applied color
coat, even though the compositions may be the same.
[0015] Also, windshields and other items such as trim moldings
typically are affixed to the body of a vehicle with an adhesive
material, typically a moisture-cured material containing isocyanate
group-containing polymers. Motor Vehicle Safety Standards (MVSS)
require that these adhesives have complete adhesion to both the
windshield and the coated substrate to which they are applied.
Similar adhesive compositions can be used as structural adhesives
as well. Such adhesives, for example, are commercially available
from Essex Specialty Products, Inc. of Auburn Hills, Mich. These
adhesive products adhere well to many cured top coating
compositions used to coat vehicles such as automobiles. It is
known, however, that these adhesive materials often do not
completely adhere to some top coats, for example, those formed from
coating compositions based on carbamate and/or urea containing
polymers. This necessitates the application of a primer coating to
the cured carbamate and/or urea-based top coatings prior to
application of the windshield adhesive to ensure compliance with
the aforementioned Motor Vehicle Safety Standards. Such primer
coatings are typically based on moisture-curable polymers similar
to those comprising the adhesive. Use of such primer coatings has
proven to be effective, but primer coating application adds an
additional and expensive step to the windshield and/or trim
installation processes.
[0016] Moreover, as discussed previously, during the assembly
process, the applied color-plus-clear coating can include surface
defects in the clear coat surface which requires repair. Some
automobile manufacturers elect to remove the defect and recoat the
repair area with the same clear coat composition. In this instance,
the cured clear coat must have excellent intercoat adhesion to the
subsequently applied clear coat. It is known, however, that some
clear coats when cured have poor intercoat adhesion with the
subsequently applied repair clear coat.
[0017] In view of the foregoing, there remains a need in the
coating industry for coating compositions which have improved
properties such as acid etch resistance and mar and scratch
resistance while maintaining excellent intercoat or interlayer
adhesion to subsequently applied coatings and/or adhesives.
[0018] Also, many adhesion promoters are known in the art. Such
adhesion promoters include, for example, phosphatized epoxy
compounds, for example, the reaction product formed from phosphoric
acid and a bisphenol A or hydrogenated bisphenol A diglycidyl
ether. Typically, such adhesion promoters are useful for promoting
adhesion of coating layers which contain them to a substrate, for
example, a metallic substrate or an elastomeric substrate or to a
previously applied coating layer. Also, such adhesion promoters can
be used advantageously to promote cohesive integrity within a
coating layer, for example, the cohesive integrity of a metal
flake-containing basecoat. Further, it is known that adhesion
promoter compositions, such as a phosphate wipe or an
adhesion-promoting primer, can be topically applied to a cured
coating to provide an adhesion promoting layer thereover, thereby
improving adhesion of a subsequently applied coating. This,
however, necessitates an additional and costly coating step in the
coating application process. It is not known, however, to include
an adhesion promoter as a component in a coating composition which
will migrate during a curing reaction through the surrounding
polymeric matrix to the surface of the resultant coating thereby
promoting the interlayer or intercoat adhesion between the
resultant coating and a subsequently applied coating.
[0019] As mentioned above, the surface of a coating can be modified
by the inclusion of one or more surface active agents, for example,
silicone oils, siloxanes, and fluorsurfactants, in the coating
compositions to improve such properties as slip and mar resistance
of such coatings. Typical surface active agents have solubility
parameters or surface energies which are sufficiently different
from the coating compositions (i.e., the composition without the
surface active agent) such that, when included in the composition,
the surface active agent can migrate or partition to the surface
region of the cured coating as the composition cures. That is, the
surface active agent is present at the surface region of the
resultant coating layer. While such surface-modified coatings can
exhibit improved slip and mar resistance, they often are difficult
to recoat. Hence, the interlayer or intercoat adhesion with a
subsequently applied coating is poor, sometimes resulting in
delamination.
[0020] It has now been found that by selecting adhesion promoting
components and surface active agents such that the solubility
parameter of the coating composition containing both the adhesion
promoting component and the surface active agent is sufficiently
different from that of an analogous coating composition which does
not contain the adhesion promoting component and the surface active
agent, that the adhesion promoting component partitions to the
surface region of the resultant coating. This can result in a
concentration of the adhesion promoting component at the surface
region which is greater than the concentration in the interior or
bulk region of the coating layer. This partitioning effect of the
adhesion promoting component can significantly increase its effect
in promoting the adhesion of the coating layer which contains the
adhesion promoter to a subsequently applied coating layer, as well
as to the substrate to which it is applied.
SUMMARY OF THE INVENTION
[0021] In one embodiment, the present invention is directed to an
improved multi-layer composite of two or more polymeric layers at
least one of which is formed from a thermosetting composition. The
composite comprises at least a first polymeric layer formed on a
substrate and a second polymeric layer over at least a portion of
the first polymeric layer, wherein in the absence of a
boron-containing compound, the first polymeric layer and the second
polymeric layer have poor interlayer adhesion. The improvement
comprises the inclusion of at least one boron-containing compound
selected from boric acid, boric acid equivalents, and mixtures
thereof in one or both of the first and second polymeric layers in
an amount sufficient to improve the interlayer adhesion of the
first polymeric layer and the second polymeric layer.
[0022] The present invention is also directed to an improved
curable coating composition used to form a multi-layer composite
coating comprising two or more cured coating layers. The
multi-layer composite coating comprises at least a first coating
layer formed on at least a portion of a substrate and a second
coating layer formed over at least a portion of the first coating
layer, wherein one or both of the first and second coating layers
is formed from the improved coating composition, and wherein in the
absence of a boron-containing compound, the first coating layer and
the second coating layer have poor interlayer adhesion. The
improvement comprises the inclusion in the curable coating
composition of a boron-containing compound selected from at least
one of boric acid, boric acid equivalents, and mixtures thereof in
an amount sufficient to improve the interlayer adhesion between the
first coating layer and the second coating layer.
[0023] In a further embodiment, the present invention is directed
to a method for improving the interlayer adhesion of a multi-layer
composite comprising two or more polymeric layers, at least one of
which is formed from a thermosetting composition. The composite
comprises at least a first polymeric layer formed on at least a
portion of a substrate and a second polymeric layer formed over at
least a portion of the first polymeric layer, wherein in the
absence of a boron-containing compound, the first polymeric layer
and the second polymeric layer have poor interlayer adhesion. The
improvement comprises the inclusion in one or both of the polymeric
layers of any of the aforementioned boron-containing compounds in
an amount sufficient to improve the interlayer adhesion of the
first polymeric layer and the second polymeric layer.
[0024] In another embodiment, the present invention provides
curable coating composition formed from components comprising (A)
at least one film-forming polymer comprising at least one reactive
functional group; (B) at least one reactant comprising at least one
functional group that is reactive with the reactive functional
group of the polymer (A); and (C) at least one compound selected
from borates, aluminates, titanates, zirconates, silicates,
siloxanes, silanes, and mixtures thereof, wherein each component is
different.
[0025] Coated substrates are also provided.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] Other than in the operating examples, or where otherwise
indicated, all numbers expressing quantities of ingredients,
reaction conditions and so forth used in the specification and
claims are to be understood as being modified in all instances by
the term "about." Accordingly, unless indicated to the contrary,
the numerical parameters set forth in the following specification
and attached claims are approximations that may vary depending upon
the desired properties sought to be obtained by the present
invention. At the very least, and not as an attempt to limit the
application of the doctrine of equivalents to the scope of the
claims, each numerical parameter should at least be construed in
light of the number of reported significant digits and by applying
ordinary rounding techniques.
[0027] Notwithstanding that the numerical ranges and parameters
setting forth the broad scope of the invention are approximations,
the numerical values set forth in the specific examples are
reported as precisely as possible. Any numerical values, however,
inherently contain certain errors necessarily resulting from the
standard deviation found in their respective testing
measurements.
[0028] Also, it should be understood that any numerical range
recited herein is intended to include all sub-ranges subsumed
therein. For example, a range of "1 to 10" is intended to include
all sub-ranges between and including the recited minimum value of 1
and the recited maximum value of 10, that is, having a minimum
value equal to or greater than 1 and a maximum value of equal to or
less than 10.
[0029] In one embodiment, the present invention provides an
improved multi-layer composite comprising at least a first
polymeric layer and a second polymeric layer formed over the first
polymeric layer thereby forming an interface region there between.
At least one of the polymeric layers is formed from a thermosetting
composition comprising an adhesion promoter composition. The
adhesion promoter composition comprises (1) at least one adhesion
promoting component, and (2) at least one surface active component.
The improvement comprises the presence of the adhesion promoting
component (1) at the interface region.
[0030] In a further embodiment, the present invention is directed
to an improved multi-layer composite comprising at least a first
polymeric layer and a second polymeric layer formed over the first
polymeric layer thereby forming an interface region there between.
The first polymeric layer has a surface region and a bulk region
and is formed from a thermosetting composition. The thermosetting
composition is formed from the following components: (A) at least
one polymer comprising one or more reactive functional groups
selected from at least one of a hydroxyl group and a carbamate
group; (B) at least one curing agent selected from at least one of
an aminoplast resin, a polyisocyanate and a blocked isocyanate; and
(C) at least one adhesion promoter composition comprising (1) at
least one adhesion promoting component selected from at least one
of boric acid, boric acid equivalents, and mixtures thereof, and
(2) at least one surface active component comprising a least one
polysiloxane comprising at least one of the following structural
units (I):
R.sup.1.sub.nR.sup.2 .sub.mSiO.sub.(4-n-m)/2 (I)
[0031] wherein each R.sup.1 is independently selected from H, a
monovalent hydrocarbon group or a siloxane group; each R.sup.2
independently is a group comprising at least one reactive
functional group, typically OR', where R' is H or an alkyl group
having 1 to 20 carbon atoms; and m and n each represent a positive
number fulfilling the requirements of 0<m<4; 0<n<4; and
2.ltoreq.(m+n)<4. The improvement comprises the presence of the
adhesion promoting component (1) at the interface region.
[0032] The adhesion promoter composition comprises at least one
adhesion promoting component (1) and at least one surface active
component (2). It should be understood that the adhesion promoter
composition can comprise the adhesion promoting component (1) and
the surface active component as separate components in an
admixture; or the adhesion promoter composition can comprise a
reaction product formed from the adhesion promoting component (1)
and the surface active component (2). Obviously, the adhesion
promoter composition can comprise the above described reaction
product formed from components (1) and (2), as well as the
component (1), and the component (2), all present as three separate
ingredients.
[0033] In one embodiment of the present invention, the adhesion
promoter composition comprises an adhesion promoting component (1)
which is selected from at least one of boron, aluminum, titanium,
zirconium, and silicon. Typically, the adhesion promoting component
(1) comprises a compound selected from at least one of a borate, an
aluminate, a titanate, a zirconate, a silicate, a siloxane, a
silane and mixtures thereof. In one specific embodiment of the
invention, the at least one adhesion promoting component (1) is
selected from at least one of a borate and an aluminate.
[0034] Examples of suitable borates are those discussed below in
detail. Examples of titanates suitable for use in the compositions
of the present invention include titanium isopropoxide, isopropyl
triostearoyl titanate, dicyclo(dioct)pyrophosphato titanate,
tetraisopropyl di(dioctyl)phosphito titanate. Suitable aluminates
include aluminum alkoxides such as aluminum isoproxide, which is
typically employed, and aluminum acetylacetonate, Exemplary of a
suitable silicate is tetraethyl orthosilicate. Suitable siloxanes
include tetraisopropyldisiloxanes and tetramethylsiloxane. Suitable
silanes include tetramethyl silyl ethers. In one embodiment of the
present invention, a polysiloxane comprising one or more hydroxyl
functional groups is employed as the surface active component (2).
In one particular embodiment of the present invention, the adhesion
promoting component (1) comprises an aluminum alkoxide, such as
aluminum triisopropoxide, and the surface active component (2)
comprises a polysiloxane comprising one or more hydroxyl
groups.
[0035] Other materials suitable for use as the surface active
component (2) are any of the surface active agents well known in
the art. As used herein, by "surface active agent" is meant any
material which tends to lower the solid surface tension or surface
energy of the "cured" composition or coating. That is, the cured
composition or coating formed from a composition comprising a
surface active agent has a lower solid surface tension or surface
energy than a cured coating formed from the analogous composition
which does not contain the surface active agent.
[0036] For purposes of the present invention, solid surface tension
can be measured according to the Owens-Wendt method using a
Rame'-Hart Contact Angle Goniometer with distilled water and
methylene iodide as reagents. Generally, a 0.02 cc drop of one
reagent is placed upon the cured coating surface and the contact
angle and its complement are measured using a standard microscope
equipped with the goniometer. The contact angle and its complement
are measured for each of three drops. The process is then repeated
using the other reagent. An average value is calculated for the six
measurements for each of the reagents. The solid surface tension is
then calculated using the Owens-Wendt equation:
{.gamma..vertline.(1+cos
.PHI.)}2=(.gamma..vertline..sup.d.gamma..sub.s.su-
p.d).sup.1/2+(.gamma..vertline..sup.p.gamma..sub.s.sup.p).sup.1/2
[0037] where .gamma..vertline. is the surface tension of the liquid
(methylene iodide=50.8, distilled water=72.8) and .gamma..sup.d and
.gamma..sup.p are the dispersion and polar components (methylene
iodide .gamma..sup.d=49.5, .gamma..sup.p=1.3; distilled water
.gamma..sup.d=21.8, .gamma..sup.d=51.0); the values for .PHI.
measured and the cos .PHI. determined. Two equations are then
setup, one for methylene iodide and one for water. The only
unknowns are .gamma..sub.s.sup.d and .gamma..sub.s.sup.p. The two
equations are then solved for the two unknowns. The two components
combined represent the total solid surface tension.
[0038] The surface active component (2) can be selected from
amphiphilic, reactive functional group-containing polysiloxanes
such as are described below, amphiphilic fluoropolymers, and
mixtures of any of the foregoing. With reference to water-soluble
or water-dispersible amphiphilic materials, the term "amphiphilic"
means a polymer having a generally hydrophilic polar end and a
water-insoluble generally hydrophobic end. Nonlimiting examples of
suitable functional group-containing polysiloxanes for use as
surface active agents include those polysiloxanes described above.
Nonlimiting examples of suitable amphiphilic fluoropolymers include
fluoroethylene-alkyl vinyl ether alternating copolymers (such as
those described in U.S. Pat. No. 4,345,057) available from Asahi
Glass Company under the tradename LUMIFLON; fluorosurfactants, such
as the fluoroaliphatic polymeric esters commercially available from
3M of St. Paul, Minn. under the tradename FLUORAD; functionalized
perfluorinated materials, such as 1H,1H-perfluoro-nonanol
commercially available from FluoroChem USA; and perfluorinated
(meth)acrylate resins.
[0039] Nonlimiting examples of other adjuvant surface active agents
suitable for use in the composition or coating of the present
invention can include anionic, nonionic and cationic surface active
agents.
[0040] Nonlimiting examples of suitable anionic surface active
agents include sulfates or sulfonates. Specific nonlimiting
examples include higher alkyl mononuclear aromatic sulfonates such
as the higher alkyl benzene sulfonates containing from 10 to 16
carbon atoms in the alkyl group and a straight- or branched-chain,
e.g., the sodium salts of decyl, undecyl, dodecyl, tridecyl,
tetradecyl, pentadecyl or hexadecyl benzene sulfonate and the
higher alkyl toluene, xylene and phenol sulfonates; alkyl
naphthalene sulfonate, and sodium dinonyl naphthalene sulfonate.
Other nonlimiting examples of suitable anionic surface active
agents include olefin sulfonates, including long chain alkenylene
sulfonates, long chain hydroxyalkane sulfonates, and mixtures of
any of the foregoing. Nonlimiting examples of other sulfate or
sulfonate detergents are paraffin sulfonates such as the reaction
products of alpha olefins and bisulfites (e.g., sodium bisulfite).
Also comprised are sulfates of higher alcohols, such as sodium
lauryl sulfate, sodium tallow alcohol sulfate, or sulfates of
mono-or di-glycerides of fatty acids (e.g., stearic monoglyceride
monosulfate), alkyl poly(ethoxy)ether sulfates including, but not
limited to, the sulfates of the condensation products of ethylene
oxide and lauryl alcohol (usually having 1-5 ethenoxy groups per
molecule); lauryl or other higher alkyl glyceryl ether sulfonates;
aromatic poly(ethenoxy)ether sulfates including, but not limited
to, the sulfates of the condensation products of ethylene oxide and
nonyl phenol (usually having 1-20 oxyethylene groups per molecule).
Further nonlimiting examples include salts of sulfated aliphatic
alcohol, alkyl ether sulfate or alkyl aryl ethoxy sulfate available
from Rhone-Poulenc under the general tradename ABEX. Phosphate
mono-or di-ester type anionic surface active agents also can be
used. These anionic surface active agents are well known in the art
and are commercially available under the general trade designation
GAFAC from GAF Corporation and under the general trade designation
TRITON from Rohm & Haas Company.
[0041] Nonlimiting examples of nonionic surface active agents
suitable for use in the cured composition or coating of the present
invention include those containing ether linkages and which are
represented by the following general formula: RO(R'O).sub.nH;
wherein the substituent group R represents a hydrocarbon group
containing 6 to 60 carbon atoms, the substituent group R'
represents an alkylene group containing 2 or 3 carbon atoms, and
mixtures of any of the foregoing, and n is an integer ranging from
2 to 100. Such nonionic surface active agents can be prepared by
treating fatty alcohols or alkyl-substituted phenols with an excess
of ethylene or propylene oxide. The alkyl carbon chain may contain
from 14 to 40 carbon atoms and may be derived from a long chain
fatty alcohol such as oleyl alcohol or stearyl alcohol. Nonionic
polyoxyethylene surface active agents of the type represented by
the formula above are commercially available under the general
trade designation SURFYNOL.RTM. from Air Products Chemicals, Inc.;
PLURONIC.RTM. or TETRONIC.RTM. from BASF Corporation; TERGITOL.RTM.
from Union Carbide; and SURFONIC.RTM. from Huntsman Corporation.
Other nonlimiting examples of suitable nonionic surface active
agents include block copolymers of ethylene oxide and propylene
oxide based on a glycol such as ethylene glycol or propylene glycol
including, but not limited to, those available from BASF
Corporation under the general trade designation PLURONIC.RTM..
[0042] As indicated above, cationic surface active agents also can
be used. Nonlimiting examples of cationic surface active agents
suitable for use in the compositions of the present invention
include acid salts of alkyl amines such as ARMAC.RTM. HT, an acetic
acid salt of n-alkyl amine available from Akzo Nobel Chemicals;
imidazoline derivatives such as CALGENE.RTM..degree. C.-100
available from Calgene Chemicals Inc.; ethoxylated amines or amides
such as DETHOX.RTM. Amine C-5, a cocoamine ethoxylate available
from Deforest Enterprises; ethoxylated fatty amines such as
ETHOX.RTM. TAM available from Ethox Chemicals, Inc.; and glyceryl
esters such as LEXEMUL.RTM. AR, a glyceryl stearate/stearaidoethyl
diethylamine available from Inolex Chemical Co.
[0043] Other examples of suitable surface active agents can include
polyacrylates. Nonlimiting examples of suitable polyacrylates
include homopolymers and copolymers of acrylate monomers, for
example polybutylacrylate and copolymers derived from acrylate
monomers (such as ethyl (meth)acrylate, 2-ethylhexylacrylate, butyl
(meth)acrylate and isobutyl acrylate), and hydroxy
ethyl(meth)acrylate and (meth)acrylic acid monomers. In one
embodiment, the polyacrylate can have amino and hydroxy
functionality. Suitable amino and hydroxyl functional acrylates are
disclosed in Example 26 below and in U.S. Pat. No. 6,013,733, which
is incorporated herein by reference. Another example of a useful
amino and hydroxyl functional copolymer is a copolymer of hydroxy
ethyl acrylate, 2-ethylhexylacrylate, isobutyl acrylate and
dimethylamino ethylmethacrylate. In another embodiment, the
polyacrylate can have acid functionality, which can be provided,
for example, by including acid functional monomers such as
(meth)acrylic acid in the components used to prepare the
polyacrylate. In another embodiment, the polyacrylate can have acid
functionality and hydroxyl functionality, which can be provided,
for example, by including acid functional monomers such as
(meth)acrylic acid and hydroxyl functional monomers such as hydroxy
ethyl (meth)acrylate in the components used to prepare the
polyacrylate.
[0044] In one particular embodiment, the thermosetting composition
used to form one or more of the polymeric layers is such that the
free energy of mixing value for an admixture of the adhesion
promoter composition and the analogous thermosetting composition
which does not contain of the adhesion promoter composition is a
positive value. In another embodiment of the present invention, the
solubility parameter of the adhesion promoter composition is
sufficiently different from the solubility parameter of the
analogous thermosetting composition which does not contain the
adhesion promoter composition, such that the resulting
thermodynamic interaction parameter value (.chi.) for the admixture
of the adhesion promoter composition and the thermosetting
composition which does not contain the adhesion promoter
composition is 0.5 or greater.
[0045] The "free energy of mixing" is defined as
.DELTA.G=.DELTA.H-T.DELTA- .S, where G is the Gibb's free energy, H
is enthalpy, S is entropy and T is temperature. In simple terms,
when the free energy of mixing (.DELTA.G) of two components is a
positive value, the two components are immiscible and will phase
separate. For example, in the instance where a coating composition
contains these two substantially immiscible components, when
applied as a coating layer one component will tend to migrate or
partition to the surface region of the coating layer while the
other will remain in the bulk region. Also, .DELTA.G for a binary
mixture containing a component 1 and a component 2 may be defined
by the following equation:
.DELTA.G=RT[(n.sub.1 ln X.sub.1+n.sub.2 ln
X.sub.2)+.chi.n.sub.1X.sub.2]
[0046] where R is the gas constant, T is temperature, X is the
volume fraction of component 1 or 2, N is the number of particles,
and .chi. ("chi") represents the thermodynamic interaction
parameter. The thermodynamic interaction parameter (.chi. or "chi")
is defined as the difference in the energy of mixing of components
1 and 2. This can be represented by the following equation:
.chi.=(.DELTA.E.sub.mix/RT)V.sub.m
[0047] where V.sub.m is the average molar volume ("reference
segment volume") and R and T are defined above. "Chi" may also be
defined as the difference in solubility parameter (SP) of two
materials.
.chi.=V.sub.m(.delta..sub.1-.delta..sub.2).sup.2RT
[0048] where .delta. is the Hildebrand solubility parameter. The
solubility parameter may be computed from a value known as the
cohesive energy density ("ced") of a material. The "ced" is related
to the heat of vaporization of a material, that is, how much energy
is required to remove a single molecule from the bulk. For
polymeric systems, such as a coating composition, where the
assumption that the entropy of mixing is exceedingly small, the
free energy expressions reduce to the energy of mixing itself, that
is .DELTA.G=.DELTA.H, and a theoretical critical point exists where
two materials become immiscible (phase separate) when "chi" is
greater than 0.5. For regular solutions, (low molecular weight
species) this critical point has a value of 2.0.
[0049] To summarize, from first principles, the "ced" for a bulk
material can be computed. The "ced" is directly related to the
solubility parameter (.delta.) as indicated above. The
thermodynamic interaction parameter "chi" (.chi.) can be computed
from the differences in the solubility parameter (.delta.) for each
of the two materials. "Chi" along with relative fractions of
materials in a mixture may be used to compute the free energy of
mixing (.DELTA.G). If .DELTA.G is a positive value, the mixture is
thermodynamically unstable and phase separation will occur.
Critical points for this condition are values of "chi" 0.5 and
greater for higher molecular weight materials such as the polymeric
components of a resinous binder system, and 2.0 for smaller
molecules. Flory, Paul J., Principles of Polymer Chemistry, Cornell
University Press (1953), Chapters XII and XIII; Polymer User Guide,
September 1996, Molecular Simulations, Inc., San Diego, Calif.;
Nicolaides, D., Parameterisation for Mesoscale Modeling, Molecular
Simulations, Inc.
[0050] Without intending to be bound by any theory, it is believed
that by such phase separation discussed above, the adhesion
promoting component (1) can be present in the interface region
between the first polymer layer and the second polymer layer,
thereby providing improved interlayer adhesion between the two.
[0051] In one embodiment of the present invention, the first
polymeric layer is formed from the thermosetting composition,
typically over a substrate, and comprises a surface region and a
bulk region. As used herein "surface region" of the cured
thermosetting composition (or of the resultant polymeric layer)
means the region which is generally parallel to the exposed
air-surface interface of the cured composition (typically formed on
a substrate) and which has thickness generally extending
perpendicularly from the surface of the cured polymeric layer to a
depth ranging from at least 20 nanometers to 200 nanometers beneath
the exposed surface. In certain embodiments, this thickness of the
surface region ranges from at least 20 nanometers to 100
nanometers, and can range from at least 20 nanometers to 50
nanometers. As used herein, "bulk region" of the cured
thermosetting composition (or the resultant polymeric layer) means
the region which extends beneath the surface region and which is
generally parallel to the surface of the substrate to which the
composition has been applied. The bulk region has a thickness
extending from its interface with the surface region through the
cured composition to the substrate or polymeric layer beneath the
cured composition.
[0052] In another embodiment of the present invention, the free
energy of mixing value of an admixture of the adhesion promoter
composition and the thermosetting composition without the adhesion
promoter composition is a positive value such that the adhesion
promoting component (1) is partitioned within the first polymeric
layer to provide a concentration of the adhesion promoting
component (1) at the surface region which is greater than the
concentration of the adhesion promoting component (1) within the
bulk region of the polymeric layer.
[0053] In yet another embodiment of the present invention, the
solubility parameter of the adhesion promoter composition is
sufficiently different from the solubility parameter of the
thermosetting composition without the adhesion promoter
composition, such that the thermodynamic interaction parameter
value for the admixture of the adhesion promoter composition and
the thermosetting composition without the adhesion promoter
composition is greater than 0.5, thereby causing the adhesion
promoting component (1) to partition within the first polymeric
layer to provide a concentration of the adhesion promoting
component (1) at the surface region which is greater than the
concentration of the adhesion promoting component (1) in the bulk
region of the first polymeric layer.
[0054] As previously mentioned, in one embodiment, the present
invention provides an improved multi-layer composite of two or more
polymeric layers at least one of which is formed from a
thermosetting composition. The composite comprises at least a first
polymeric layer formed on a substrate and a second polymeric layer
over at least a portion of said first polymeric layer, wherein in
the absence of an adhesion promoter composition, typically
boron-containing compound the first polymeric layer and the second
polymeric layer have poor interlayer adhesion. The improvement
comprises the inclusion of at least one boron-containing compound
selected from boric acid, boric acid equivalents, and mixtures
thereof in one or both of the first and second polymeric layers in
an amount sufficient to improve the interlayer adhesion of the
first and second polymeric layers.
[0055] It should be understood that the composite of the present
invention can comprise only two polymeric layers, wherein the first
polymeric layer is formed on at least a portion of a substrate and
the second polymeric layer is formed over at least a portion of the
first polymeric layer. Alternatively, the composite of the present
invention can comprise the first polymeric layer over at least a
portion of a substrate, and the second polymeric layer formed over
at least a portion of the first polymeric layer, where there are
one or more subsequent polymeric layers formed over at least a
portion of the second polymeric layer.
[0056] For example, the first polymeric layer can comprise a
primer-surfacer coating and the second polymeric layer can comprise
a color-enhancing base coating to which has been subsequently
applied a transparent top coat. Also, the first polymeric layer can
comprise an electrodepositable primer coating and the second
polymeric layer can comprise a primer-surfacer coating to which has
been subsequently applied an appearance enhancing monocoat or a
color-plus-clear coating system. Additionally, the first polymeric
layer can comprise a transparent clear coat (as the clear coat in a
color-plus-clear coating system) and the second polymeric layer can
comprise a repair clear coat.
[0057] Also, it should be understood that as used herein, a
polymeric layer or composition formed "over" at least a portion of
a "substrate" refers to a polymeric layer or composition formed
directly on at least a portion of the substrate surface, as well as
a polymeric layer or composition formed over any coating or
adhesion promoter material which was previously applied to at least
a portion of the substrate.
[0058] That is, the "substrate" upon which the first polymeric
layer has been formed can comprise a metallic or elastomeric
substrate to which one or more coating layers have been previously
applied. For example, the "substrate" can comprise a metallic
substrate and a weldable primer coating over at least a portion of
the substrate surface, and the first polymeric layer can comprise
an electrodepositable primer coating. Likewise, the "substrate" can
comprise a metallic substrate having an electrodepositable primer
formed over at least a portion thereof, and a primer-surfacer
coating over at least a portion of the electrodepositable primer.
The first polymeric layer can comprise, for example, a pigmented
base coat over at least a portion of this multli-layer "substrate",
and the second polymeric layer can comprise a pigment-free top coat
formed over at least a portion of the pigmented base coat.
[0059] At least one of the first and second polymeric layers is
formed from a thermosetting composition. In the multi-layer
composite of the present invention, the first polymeric only can
comprise a thermosetting composition, the second layer only can
comprise a thermosetting composition, or, alternatively both the
first and second polymeric layers can comprise a thermosetting
composition. In the latter instance, the thermosetting composition
from which the first polymeric layer is formed and the
thermosetting composition from which the second polymeric layer is
formed can be the same or different thermosetting composition.
[0060] In one embodiment of the present invention, both the first
polymeric layer and the second polymeric layer are formed from a
thermosetting composition. In another embodiment, the thermosetting
composition comprises a curable coating composition as described
below.
[0061] As used herein, by "thermosetting composition" is meant one
which "sets" irreversibly upon curing or crosslinking, wherein the
polymer chains of the polymeric components are joined together by
covalent bonds. This property is usually associated with a
cross-linking reaction of the composition constituents often
induced by heat or radiation. Hawley, Gessner G., The Condensed
Chemical Dictionary, Ninth Edition., page 856; Surface Coatings,
vol. 2, Oil and Colour Chemists' Association, Australia, TAFE
Educational Books (1974). Once cured or crosslinked, a
thermosetting composition will not melt upon the application of
heat and is insoluble in solvents. By contrast, a "thermoplastic
composition" comprises polymeric components which are not joined by
covalent bonds and thereby can undergo liquid flow upon heating and
are soluble in solvents. Saunders, K. J., Organic Polymer
Chemistry, pp. 41-42, Chapman and Hall, London (1973).
[0062] In one embodiment of the present invention, the substrate
can comprise a metallic substrate. Examples of suitable metallic
substrates can include ferrous metals and non-ferrous metals.
Suitable ferrous metals include iron, steel, and alloys thereof.
Non-limiting examples of useful steel materials include cold-rolled
steel, galvanized (zinc coated) steel, electrogalvanized steel,
stainless steel, pickled steel, GALVANNEAL.RTM., GALVALUME.RTM.,
and GALVAN.RTM. zinc-aluminum alloys coated upon steel, and
combinations thereof. Useful non-ferrous metals include aluminum,
zinc, magnesium and alloys thereof. Combinations or composites of
ferrous and non-ferrous metals can also be used.
[0063] In another embodiment of the present invention, the
substrate can comprise an elastomeric substrate. Suitable
elastomeric substrates can include any of the thermoplastic or
thermoset synthetic materials well known in the art. Nonlimiting
examples' of suitable flexible elastomeric substrate materials
include polyethylene, polypropylene, thermoplastic polyolefin
("TPO"), reaction injected molded polyurethane ("RIM") and
thermoplastic polyurethane ("TPU").
[0064] Nonlimiting examples of thermoset materials useful as
substrates in connection with the present invention include
polyesters, epoxides, phenolics, polyurethanes such as "RIM"
thermoset materials, and mixtures of any of the foregoing.
Nonlimiting examples of suitable thermoplastic materials include
thermoplastic polyolefins such as polyethylene, polypropylene,
polyamides such as nylon, thermoplastic polyurethanes,
thermoplastic polyesters, acrylic polymers, vinyl polymers,
polycarbonates, acrylonitrile-butadiene-styrene ("ABS") copolymers,
ethylene propylene diene terpolymer ("EPDM") rubber, copolymers,
and mixtures of any of the foregoing.
[0065] If desired, the polymeric substrates described above can
have an adhesion promoter present on the surface of the substrate
over which any of a number of coating compositions (including the
coating compositions of the present invention as described below)
can be applied. To facilitate adhesion of organic coatings to
polymeric substrates, the substrate can be pretreated using an
adhesion promoter layer or tie coat, e.g., a thin layer 0.25 mils
(6.35 microns) thick, or by flame or corona pretreatment.
[0066] Suitable adhesion promoters for use over polymeric
substrates include chlorinated polyolefin adhesion promoters such
as are described in U.S. Pat. Nos. 4,997,882; 5,319,032; and
5,397,602, incorporated by reference herein. Other useful adhesion
promoting coatings are disclosed in U.S. Pat. Nos. 6,001,469 (a
coating composition containing a saturated polyhydroxylated
polydiene polymer having terminal hydroxyl groups), 5,863,646 (a
coating composition having a blend of a saturated polyhydroxylated
polydiene polymer and a chlorinated polyolefin) and 5,135,984 (a
coating composition having an adhesion promoting material obtained
by reacting a chlorinated polyolefin, maleic acid anhydride, acryl
or methacryl modified hydrogenated polybutadiene containing at
least one acryloyl group or methacryloyl group per unit molecule,
and organic peroxide), which are incorporated herein by
reference.
[0067] When the substrates are used as components to fabricate
automotive vehicles (including, but not limited to, automobiles,
trucks and tractors) they can have any shape, and can be selected
from the metallic and/or flexible substrates described above.
Typical shapes of automotive body components can include body side
moldings, fenders, bumpers, hoods, and trim for automotive
vehicles.
[0068] Also, as mentioned above, in the absence of an adhesion
promoting composition, typically a boron-containing compound, the
first polymeric layer and said second polymeric layer have poor
interlayer adhesion. That is, the second polymeric layer, in the
absence of a boron-containing compound present in either of the
first polymeric layer or the second polymeric layer, the two layers
have poor interlayer (i.e., intercoat) adhesion. As used herein, by
"poor interlayer adhesion" is meant that the second polymeric layer
will have delamination or adhesion loss from the first polymeric
layer sufficient to be given a rating of 3 or lower, as determined
in accordance with ASTM-D 3359-97, method B, using the rating scale
specified therein.
[0069] The improvement comprises the inclusion of an adhesion
promoting composition, typically a boron-containing compound, in
one or both of the first polymeric layer and the second polymeric
layer in an amount sufficient to improve the interlayer adhesion of
the first polymeric layer and the second polymeric layer. The
boron-containing compound can be present in the first polymeric
layer only, the second polymeric layer only, or, alternatively, in
both the first polymeric layer and the second polymeric layer. In
one embodiment of the present invention, the boron-containing
compound is present in the first polymeric layer.
[0070] Also, it should be understood that the adhesion promoter,
for example, a boron-containing compound, can be present in any of
the polymeric layers comprising the substrate over at least a
portion of which is formed the first polymeric layer, as well as
any of the polymeric layers that can be subsequently formed over at
least a portion of the second polymeric layer.
[0071] In the multi-layer composite of the present invention, the
boron-containing compound can comprise a compound selected from
boric acid, boric acid equivalents, and mixtures thereof.
[0072] As used herein, in the specification and in the claims, by
"boric acid equivalents" is meant any of the numerous
boron-containing compounds which can hydrolyze in aqueous media to
form boric acid. As used herein, by "boric acid equivalents" is
meant any of the numerous boron-containing compounds which can
hydrolyze in aqueous media to form boric acid. Specific, but
non-limiting examples of boric acid equivalents include boron
oxides, for example, B.sub.2O.sub.3; boric acid esters such as
those obtained by the reaction of boric acid with an alcohol or
phenol, for example, trimethyl borate, triethyl borate,
tri-n-propyl borate, tri-n-butyl borate, triphenyl borate,
triisopropyl borate, tri-t-amyl borate, triphenylborate,
trimethoxyboroxine, tri-2-cyclohexylcyclohexyl borate,
triethanolamine borate, triisopropylamine borate, mannitol borate,
glycerol borate and triisopropanolamine borate.
[0073] Additionally, other amino-containing borates and tertiary
amine salts of boric acid may be useful. Such boron-containing
compounds include, but are not limited to,
2-(beta-dimethylaminoisopropoxy)-4,5-dim-
ethyl-1,3,2-dioxaborolane,
2-(beta-diethylaminoethoxy)-4,4,6-trimethyl-1,3- ,2-dioxaborinane,
2-(beta-dimethylaminoethoxy)-4,4,6-trimethyl-1,3,2-dioxa- borinane,
2-(betha-diisopropylaminoethoxy-1,3,2-dioxaborinane,
2-(beta-dibutylaminoethoxy)-4-methyl-1,3,2-dioxaborinane,
2-(gamma-dimethylaminopropoxy)-1,3,6,9-tetrapxa-2-boracycloundecane,
and
2-(beta-dimethylaminoethoxy)4,4-(4-hydorxybutyl)-1,3,2-dioxaborolane.
[0074] Boric acid equivalents can also include metal salts of boric
acid (i.e., metal borates) provided that such metal borates can
readily dissociate in aqueous media to form boric acid. Suitable
examples of metal borates include, for example, calcium borate,
potassium borates such as potassium metaborate, potassium
tetraborate, potassium pentaborate, potassium hexaborate, and
potassium octaborate, sodium borates such as sodium perborate,
sodium metaborate, sodium diborate, sodium tetraborate, sodium
pentaborate, sodium perborate, sodium hexaborate, and sodium
octaborate, Likewise, ammonium borates can be useful.
[0075] Suitable boric acid equivalents can also include organic
oligomeric and polymeric compounds comprising boron-containing
moieties. Suitable examples include polymeric borate esters, such
as those formed by reacting an active hydrogen-containing polymer,
for example, a hydroxyl functional group-containing acrylic polymer
or polysiloxane polymer, with boric acid and/or a borate ester to
form a polymer having borate ester groups.
[0076] Polymers suitable for this purpose can include any of a
variety of active hydrogen-containing polymers such as those
selected from at least one of acrylic polymers, polyester polymers,
polyurethane polymers, polyether polymers and silicon-based
polymers. As used herein, by "silicon-based polymers" is meant a
polymer comprising one or more --SiO-- units in the backbone. Such
silicon-based polymers can include hybrid polymers, such as those
comprising organic polymeric blocks with one or more --SiO-- units
in the backbone.
[0077] Examples of active hydrogen-containing polymers suitable for
this purpose include polymers comprising functional groups selected
from at least one of a hydroxyl group, an amine group, an epoxy
group, a carbamate group, a urea group, and a carboxylic acid
group. In a particular embodiment of the present invention, the
boron-containing compound is formed by reacting boric acid and/or a
borate ester with at least one polymer selected from an acrylic
polyol, a polyester polyol, a polyurethane polyol, a polyether
polyol, a polysiloxane polyol and mixtures thereof.
[0078] In one embodiment of the present invention, the
boron-containing compound comprises a polysiloxane borate ester
formed from reactants (A) at least one polysiloxane comprising at
least one of the following structural units (I):
R.sup.1.sub.nR.sup.2.sub.mSiO.sub.(4-n-m)/2 (I)
[0079] wherein each R.sup.1, which may be identical or different,
represents H, OH, a monovalent hydrocarbon group or a monovalent
siloxane group; each R.sup.2, which may be identical or different,
represents a group comprising at least one reactive functional
group, wherein m and n fulfill the requirements of 0<n<4,
0<m<4 and 2.ltoreq.(m+n)<4; and (B) at least one
boron-containing compound selected from at least one of boric acid,
a boric acid equivalent, and mixtures thereof.
[0080] It should be understood that the "at least one polysiloxane
comprising at least one structural unit (I)" above is a polymer
that contains at least two Si atoms per molecule. As used herein,
the term "polymer" in meant to encompass oligomer, and includes
without limitation both homopolymers and copolymers. It should also
be understood that the at least one polysiloxane can include
linear, branched, dendritic or cyclic polysiloxanes.
[0081] Moreover, as used herein, "formed from" denotes open, e.g.,
"comprising," claim language. As such, it is intended that a
composition "formed from" a list of recited components be a
composition comprising at least these recited components, and can
further comprise other, nonrecited components, during the
composition's formation.
[0082] Also, as used herein, the term "reactive" refers to a
functional group that forms a covalent bond with another functional
group under conditions sufficient to cure the composition.
[0083] As used herein, the phrase "each component is different"
refers to components which do not have the same chemical structure
as other components in the composition.
[0084] Each of m and n depicted in the at least one structural unit
(I) above fulfill the requirements of 0<n<4, 0<m<4 and
2.ltoreq.(m+n)<4. When (m+n) is 3, the value represented by n
can be 2 and the value represented by m is 1. Likewise, when (m+n)
is 2, the value represented by each of n and m is 1.
[0085] As used herein, the term "cure" as used in connection with a
composition, e.g., "composition when cured," shall mean that any
crosslinkable components of the composition are at least partially
crosslinked. In certain embodiments of the present invention, the
crosslink density of the crosslinkable components, i.e., the degree
of crosslinking, ranges from 5% to 100% of complete crosslinking.
In other embodiments, the crosslink density ranges from 35% to 85%
of full crosslinking. In other embodiments, the crosslink density
ranges from 50% to 85% of full crosslinking. One skilled in the art
will understand that the presence and degree of crosslinking, i.e.,
the crosslink density, can be determined by a variety of methods,
such as dynamic mechanical thermal analysis (DMTA) using a TA
Instruments DMA 2980 DMTA analyzer conducted under nitrogen. This
method determines the glass transition temperature and crosslink
density of free films of coatings or polymers. These physical
properties of a cured material are related to the structure of the
crosslinked network.
[0086] As used herein, a "monovalent hydrocarbon group" means a
monovalent group having a backbone repeat unit based exclusively on
carbon. As used herein, "monovalent" refers to a substituent group
that, as a substituent group, forms only one single, covalent bond.
For example, a monovalent group on the at least one polysiloxane
will form one single covalent bond to a silicon atom in the
backbone of the at least one polysiloxane polymer. As used herein,
"hydrocarbon groups" are intended to encompass both branched and
unbranched hydrocarbon groups.
[0087] Thus, when referring to a "monovalent hydrocarbon group,"
the hydrocarbon group can be branched or unbranched, acyclic or
cyclic, saturated or unsaturated, or aromatic, and can contain from
1 to 24 (or in the case of an aromatic group from 3 to 24) carbon
atoms. Nonlimiting examples of such hydrocarbon groups include
alkyl, alkoxy, aryl, alkaryl, and alkoxyaryl groups. Nonlimiting
examples of lower alkyl groups include, for example, methyl, ethyl,
propyl, and butyl groups. As used herein, "lower alkyl" refers to
alkyl groups having from 1 to 6 carbon atoms. One or more of the
hydrogen atoms of the hydrocarbon can be substituted with
heteroatoms. As used herein, "heteroatoms" means elements other
than carbon, for example, oxygen, nitrogen, and halogen atoms.
[0088] As used herein, "siloxane" means a group comprising a
backbone comprising two or more --SiO-- groups. For example, the
siloxane groups represented by R.sup.1, which is discussed above,
and R, which is discussed below, can be branched or unbranched, and
linear or cyclic. The siloxane groups can be substituted with
pendant organic substituent groups, for example, alkyl, aryl, and
alkaryl groups. The organic substituent groups can be substituted
with heteroatoms, for example, oxygen, nitrogen, and halogen atoms,
reactive functional groups, for example, those reactive functional
groups discussed above with reference to R.sup.2, and mixtures of
any of the foregoing.
[0089] In one embodiment, the at least one polysiloxane (A), which
is used to form the polysiloxane borate ester, comprises at least
two reactive functional groups. The at least one polysiloxane can
have a reactive group equivalent weight ranging from 50 to 1000 mg
per gram of the at least one polysiloxane. In one embodiment, the
at least one polysiloxane has a hydroxyl group equivalent weight
ranging from 50 to 1000 mg KOH per gram of the at least one
polysiloxane. In another embodiment, the at least one polysiloxane
has a hydroxyl group equivalent weight ranging from 100 to 300 mg
KOH per gram of the at least one polysiloxane, while in another
embodiment, the hydroxyl group equivalent weight ranges from 100 to
500 mg KOH per gram.
[0090] In another embodiment, R.sup.2 (see structural unit I
above), which may be identical or different, represents a group
comprising at least one reactive functional group selected from a
hydroxyl group, a carboxyl group, an isocyanate group, a blocked
isocyanate group, a primary amine group, a secondary amine group,
an amide group, a carbamate group, a urea group, a urethane group,
a vinyl group, an unsaturated ester group such as an acrylate group
and a methacrylate group, a maleimide group, a fumarate group, an
onium salt group such as a sulfonium group and an ammonium group,
an anhydride group, a hydroxy alkylamide group, and an epoxy
group.
[0091] In another embodiment, the at least one R.sup.2 group
represents a group comprising at least one reactive functional
group selected from a hydroxyl group and a carbamate group. In yet
another embodiment, the at least one R.sup.2 group represents a
group comprising at least two reactive functional groups selected
from a hydroxyl group and a carbamate group. In another embodiment,
the at least one R.sup.2 group represents a group comprising an
oxyalkylene group and at least two hydroxyl groups.
[0092] In one embodiment, the at least one polysiloxane (A), which
is used to form the polysiloxane borate ester, has the following
structure (II) or (III): 1
[0093] wherein: m has a value of at least 1; m' ranges from 0 to
75; n ranges from 0 to 75; n' ranges from 0 to 75; each R, which
may be identical or different, is selected from H, OH, a monovalent
hydrocarbon group, a monovalent siloxane group, and mixtures of any
of the foregoing; and --R.sup.a comprises the following structure
(IV):
--R.sup.3--X (IV)
[0094] wherein --R.sup.3 is selected from an alkylene group, an
oxyalkylene group, an alkylene aryl group, an alkenylene group, an
oxyalkenylene group, and an alkenylene aryl group; and X represents
a group which comprises at least one reactive functional group
selected from a hydroxyl group, a carboxyl group, an isocyanate
group, a blocked isocyanate group, a primary amine group, a
secondary amine group, an amide group, a carbamate group, a urea
group, a urethane group, a vinyl group, an unsaturated ester group
such as an acrylate group and a methacrylate group, a maleimide
group, a fumarate group, an onium salt group such as a sulfonium
group and an ammonium group, an anhydride group, a hydroxy
alkylamide group, and an epoxy group.
[0095] In one embodiment of the present invention, X represents a
group which comprises at least one reactive functional group
selected from a hydroxyl group, a carboxyl group, a primary amine
group, a secondary amine group, an amide group, a carbamate group,
a urea group, an anhydride group, a hydroxy alkylamide group, and
an epoxy group.
[0096] As used herein, "alkylene" refers to an acyclic or cyclic,
saturated hydrocarbon group having a carbon chain length of from
C.sub.2 to C.sub.25. Nonlimiting examples of suitable alkylene
groups include, but are not limited to, those derived from
propenyl, 1-butenyl, 1-pentenyl, 1-decenyl, and 1-heneicosenyl,
such as, for example (CH.sub.2).sub.3, (CH.sub.2).sub.4,
(CH.sub.2).sub.5, (CH.sub.2).sub.10, and (CH.sub.2).sub.23,
respectively, as well as isoprene and myrcene.
[0097] As used herein, "oxyalkylene" refers to an alkylene group
containing at least one oxygen atom bonded to, and interposed
between, two carbon atoms and having an alkylene carbon chain
length of from C.sub.2 to C.sub.25. Nonlimiting examples of
suitable oxyalkylene groups include those derived from
trimethylolpropane monoallyl ether, trimethylolpropane diallyl
ether, pentaerythritol monoallyl ether, polyethoxylated allyl
alcohol, and polypropoxylated allyl alcohol, such as
--(CH.sub.2).sub.3OCH.sub.2C(CH.sub.2OH).sub.2(CH.sub.2CH.sub.2--).
[0098] As used herein, "alkylene aryl" refers to an acyclic
alkylene group substituted with at least one aryl group, for
example, phenyl, and having an alkylene carbon chain length of
C.sub.2 to C.sub.25. The aryl group can be further substituted, if
desired. Nonlimiting examples of suitable substituent groups for
the aryl group include, but are not limited to, hydroxyl groups,
benzyl groups, carboxylic acid groups, and aliphatic hydrocarbon
groups. Nonlimiting examples of suitable alkylene aryl groups
include, but are not limited to, those derived from styrene and
3-isopropenyl-.varies.,.varies.-dimethylbenzyl isocyanate, such as
--(CH.sub.2).sub.2C.sub.6H.sub.4-- and
--CH.sub.2CH(CH.sub.3)C.sub.6H.sub- .3(C(CH.sub.3).sub.2(NCO). As
used herein, "alkenylene" refers to an acyclic or cyclic
hydrocarbon group having one or more double bonds and having an
alkenylene carbon chain length of C.sub.2 to C.sub.25. Nonlimiting
examples of suitable alkenylene groups include those derived from
propargyl alcohol and acetylenic diols, for example,
2,4,7,9-tetramethyl-5-decyne-4,7-diol which is commercially
available from Air Products and Chemicals, Inc. of Allentown, Pa.
as SURFYNOL 104.
[0099] Formulae (II) and (III) are diagrammatic, and are not
intended to imply that the parenthetical portions are necessarily
blocks, although blocks may be used where desired. In some cases
the polysiloxane may comprise a variety of siloxane units. This is
increasingly true as the number of siloxane units employed
increases and especially true when mixtures of a number of
different siloxane units are used. In those instances where a
plurality of siloxane units are used and it is desired to form
blocks, oligomers can be formed which can be joined to form the
block compound. By judicious choice of reactants, compounds having
an alternating structure or blocks of alternating structure may be
used.
[0100] In one embodiment of the present invention the substituent
R.sup.3 represents an oxyalkylene group. In another embodiment,
R.sup.3 represents an oxyalkylene group, and X represents a group
which comprises at least two reactive functional groups.
[0101] In another embodiment of the present invention where the at
least one polysiloxane (A) has the structure (II) or (III)
described above, (n+m) ranges from 2 to 9. In yet another
embodiment where the at least one polysiloxane have the structure
(II) or (III) described above, (n+m) ranges from 2 to 3. In another
embodiment, where the at least one polysiloxane have the structure
(II) or (III) described above, (n'+m') ranges from 2 to 9. In
another embodiment where the at least one polysiloxane has the
structure (II) or (III) described above, (n'+m') ranges from 2 to
3.
[0102] In yet another embodiment of the present invention, the
substituent X represents a group comprising at least one reactive
functional group selected from a hydroxyl group and a carbamate
group. In another embodiment, the substituent X represents a group
which comprises at least two hydroxyl groups. In yet another
embodiment, X represents a group which comprises at least one group
selected from H, a monohydroxy-substituted organic group, and a
group having the following structure (V):
R.sup.4--(--CH.sub.2--OH).sub.p (V)
[0103] wherein the substituent group R.sup.4 represents
--CH.sub.2--C--R.sup.3
[0104] when p is 2 and the substituent group R.sup.3 represents a
C.sub.1 to C.sub.4 alkylene group, or the substituent group R.sup.4
represents --CH.sub.2--C-- when p is 3, wherein at least a portion
of X represents a group having the structure (V). In another
embodiment, where the polysiloxane (A) has the structure (I) or
(II) described above, m is 2 and p is 2.
[0105] In another embodiment of the present invention, the
polysiloxane (A) is formed from at least the following reactants:
(i) at least one polysiloxane of the formula (VI): 2
[0106] wherein each substituent group R, which may be identical or
different, represents a group selected from H, OH, a monovalent
hydrocarbon group, a monovalent siloxane group, and mixtures of any
of the foregoing; at least one of the groups represented by R is H,
and n' ranges from 0 to 100, also can range from 0 to 10, and can
further range from 0 to 5, such that the percent of SiH content of
the polysiloxane ranges from 2 to 50 percent, and can range from 5
to 25 percent; and (ii) at least one molecule which comprises at
least functional group selected from a hydroxyl group, a carboxyl
group, an isocyanate group, a blocked isocyanate group, a primary
amine group, a secondary amine group, an amide group, a carbamate
group, a urea group, a urethane group, a vinyl group, an
unsaturated ester group such as an acrylate group and a
methacrylate group, a maleimide group, a fumarate group, an onium
salt group such as a sulfonium group and an ammonium group, an
anhydride group, a hydroxy alkylamide group, and an epoxy group and
at least one unsaturated bond capable of undergoing a
hydrosilylation reaction. In another embodiment, the at least one
functional group comprises hydroxyl groups.
[0107] It should be appreciated that the various R groups can be
the same or different, and, in certain embodiments, the R groups
will be entirely monovalent hydrocarbon groups or will be a mixture
of different groups such as, for example, monovalent hydrocarbon
groups and hydroxyl groups.
[0108] In another embodiment, this reaction product is ungelled. As
used herein, "ungelled" refers to a reaction product that is
substantially free of crosslinking and has an intrinsic viscosity
when dissolved in a suitable solvent, as determined, for example,
in accordance with ASTM-D1795 or ASTM-D4243. The intrinsic
viscosity of the reaction product is an indication of its molecular
weight. A gelled reaction product, on the other hand, since it is
of an extremely high molecular weight, will have an intrinsic
viscosity too high to measure. As used herein, a reaction product
that is "substantially free of crosslinking" refers to a reaction
product that has a weight average molecular weight (Mw), as
determined by gel permeation chromatography, of less than
1,000,000.
[0109] It also should be noted that the level of unsaturation
contained in reactant (ii) above, can be selected to obtain an
ungelled reaction product. In other words, when a polysiloxane
containing silicon hydride (i) having a higher average value of
Si--H functionality is used, reactant (ii) can have a lower level
of unsaturation. For example, the polysiloxane containing silicon
hydride (i) can be a low molecular weight material where n' ranges
from 0 to 5 and the average value of Si--H functionality is two or
less. In this case, reactant (ii) can contain two or more
unsaturated bonds capable of undergoing hydrosilylation reaction
without the occurrence of gelation.
[0110] Nonlimiting examples of polysiloxanes containing silicon
hydride (i) include 1,1,3,3-tetramethyl disiloxane where n' is 0
and the average Si--H functionality is two; and polymethyl
polysiloxane containing silicon hydride, where n' ranges from 4 to
5 and the average Si--H functionality is approximately two, such as
is commercially available from BASF Corporation as MASILWAX
BASE.RTM..
[0111] Materials for use as reactant (ii) above can include
hydroxyl functional group-containing allyl ethers such as those
selected from trimethylolpropane monoallyl ether, pentaerythritol
monoallyl ether, trimethylolpropane diallyl ether, polyoxyalkylene
alcohols such as polyethoxylated alcohol, polypropoxylated alcohol,
and polybutoxylated alcohol, undecylenic acid-epoxy adducts, allyl
glycidyl ether-carboxylic acid adducts, and mixtures of any of the
foregoing. Mixtures of hydroxyl functional polyallyl ethers with
hydroxyl functional monoallyl ethers or allyl alcohols are suitable
as well. In certain instances, reactant (ii) can contain at least
one unsaturated bond in a terminal position. Reaction conditions
and the ratio of reactants (i) and (ii) are selected so as to form
the desired functional group.
[0112] The hydroxyl functional group-containing polysiloxane (A)
can be prepared by reacting a polysiloxane containing hydroxyl
functional groups with an anhydride to form the half-ester acid
group under reaction conditions that favor only the reaction of the
anhydride and the hydroxyl functional groups, and avoid further
esterification from occurring. Nonlimiting examples of suitable
anhydrides include hexahydrophthalic anhydride, methyl
hexahydrophthalic anhydride, phthalic anhydride, trimellitic
anhydride, succinic anhydride, chlorendic anhydride, alkenyl
succinic anhydride, and substituted alkenyl anhydrides such as
octenyl succinic anhydride, and mixtures of any of the
foregoing.
[0113] The half-ester group-containing reaction product thus
prepared can be further reacted with a monoepoxide to form a
polysiloxane containing secondary hydroxyl group(s). Nonlimiting
examples of suitable monoepoxides are phenyl glycidyl ether,
n-butyl glycidyl ether, cresyl glycidyl ether, isopropyl glycidyl
ether, glycidyl versatate, for example, CARDURA E available from
Shell Chemical Co., and mixtures of any of the foregoing.
[0114] In another embodiment of the present invention, the at least
one polysiloxane (A) is a carbamate functional group-containing
polysiloxane which comprises the reaction product of at least the
following reactants:
[0115] (i) at least one polysiloxane containing silicon hydride of
structure (VI) above where R and n' are as described above for that
structure;
[0116] (ii) at least one hydroxyl functional group-containing
material having one or more unsaturated bonds capable of undergoing
hydrosilylation reaction as described above; and
[0117] (iii) at least one low molecular weight carbamate functional
material, comprising the reaction product of an alcohol or glycol
ether and a urea.
[0118] Examples of such "low molecular weight carbamate functional
material" include, but are not limited to, alkyl carbamate and
hexyl carbamates, and glycol ether carbamates described in U.S.
Pat. Nos. 5,922,475 and 5,976,701, which is incorporated herein by
reference.
[0119] The carbamate functional groups can be incorporated into the
polysiloxane by reacting the hydroxyl functional group-containing
polysiloxane with the low molecular weight carbamate functional
material via a "transcarbamoylation" process. The low molecular
weight carbamate functional material, which can be derived from an
alcohol or glycol ether, can react with free hydroxyl groups of a
polysiloxane polyol, that is, material having an average of two or
more hydroxyl groups per molecule, yielding a carbamate functional
polysiloxane (A) and the original alcohol or glycol ether. Reaction
conditions and the ratio of reactants (i), (ii) and (iii) are
selected so as to form the desired groups.
[0120] The low molecular weight carbamate functional material can
be prepared by reacting the alcohol or glycol ether with urea in
the presence of a catalyst such as butyl stannoic acid. Nonlimiting
examples of suitable alcohols include lower molecular weight
aliphatic, cycloaliphatic and aromatic alcohols, for example,
methanol, ethanol, propanol, butanol, cyclohexanol, 2-ethylhexanol,
and 3-methylbutanol. Nonlimiting examples of suitable glycol ethers
include ethylene glycol methyl ether, and propylene glycol methyl
ether. The incorporation of carbamate functional groups into the
polysiloxane also can be achieved by reacting isocyanic acid with
free hydroxyl groups of the polysiloxane.
[0121] As aforementioned, in addition to or in lieu of hydroxyl or
carbamate functional groups, the at least one polysiloxane (A) can
contain one or more other reactive functional groups such as
carboxyl groups, isocyanate groups, blocked isocyanate groups,
carboxylate groups, primary or secondary amine groups, amide
groups, urea groups, urethane groups, an anhydride group, a hydroxy
alkylamide group, epoxy groups, and mixtures of any of the
foregoing.
[0122] When the at least one polysiloxane (A) contains carboxyl
functional groups, the at least one polysiloxane (A) can be
prepared by reacting at least one polysiloxane containing hydroxyl
functional groups as described above with a polycarboxylic acid or
anhydride. Nonlimiting examples of polycarboxylic acids suitable
for use include adipic acid, succinic acid, and dodecanedioic acid.
Nonlimiting examples of suitable anhydrides include those described
above. Reaction conditions and the ratio of reactants are selected
so as to form the desired functional groups.
[0123] In the case where at least one polysiloxane (A) contains one
or more isocyanate functional groups, the at least one polysiloxane
can be prepared by reacting at least one polysiloxane containing
hydroxyl functional groups, as described above, with a
polyisocyanate, such as a diisocyanate. Nonlimiting examples of
suitable polyisocyanates include aliphatic polyisocyanates, such
as, for example, aliphatic diisocyanates, for example,
1,4-tetramethylene diisocyanate and 1,6-hexamethylene diisocyanate;
cycloaliphatic polyisocyanates, for example, 1,4-cyclohexyl
diisocyanate, isophorone diisocyanate, and .alpha.,.alpha.-xylylene
diisocyanate; and aromatic polyisocyanates, for example,
4,4'-diphenylmethane diisocyanate, 1,3-phenylene diisocyanate, and
tolylene diisocyanate. These and other suitable polyisocyanates are
described in more detail in U.S. Pat. No. 4,046,729, at column 5,
line 26 to column 6, line 28, incorporated herein by reference.
Reaction conditions and the ratio of reactants are selected so as
to form the desired functional groups.
[0124] The substituent X in structure (IV) can comprise an
oligomeric or polymeric urethane or urea-containing material which
is terminated with isocyanate, hydroxyl, primary or secondary amine
functional groups, or mixtures of any of the foregoing. When the
substituent X comprises such functional groups, the at least one
polysiloxane can be the reaction product of at least one
polysiloxane polyol as described above, one or more polyisocyanates
and, optionally, one or more compounds having at least two active
hydrogen atoms per molecule selected from hydroxyl groups, primary
amine groups, and secondary amine groups.
[0125] Nonlimiting examples of suitable polyisocyanates are those
described above. Nonlimiting examples of compounds having at least
two active hydrogen atoms per molecule include polyols and
polyamines containing primary or secondary amine groups.
[0126] Nonlimiting examples of suitable polyols include
polyalkylene ether polyols, including thio ethers; polyester
polyols, including polyhydroxy polyesteramides; and
hydroxyl-containing polycaprolactones and hydroxy-containing
acrylic interpolymers. Also useful are polyether polyols formed
from the oxyalkylation of various polyols, for example, glycols
such as ethylene glycol, 1,6-hexanediol, Bisphenol A, and the like,
or higher polyols such as trimethylolpropane, pentaerythritol and
the like. Polyester polyols also can be used. These and other
suitable polyols are described in U.S. Pat. No. 4,046,729 at column
7, line 52 to column 8, line 9; column 8, line 29 to column 9, line
66; and U.S. Pat. No. 3,919,315 at column 2, line 64 to column 3,
line 33, both incorporated herein by reference.
[0127] Nonlimiting examples of suitable polyamines include primary
or secondary diamines or polyamines in which the groups attached to
the nitrogen atoms can be saturated or unsaturated, aliphatic,
alicyclic, aromatic, aromatic-substituted-aliphatic,
aliphatic-substituted-aromatic and heterocyclic. Exemplary suitable
aliphatic and alicyclic diamines include 1,2-ethylene diamine,
1,2-porphylene diamine, 1,8-octane diamine, isophorone diamine,
propane-2,2-cyclohexyl amine, and the like. Suitable aromatic
diamines include phenylene diamines and the toluene diamines, for
example, o-phenylene diamine and p-toylene diamine. These and other
suitable polyamines are described in detail in U.S. Pat. No.
4,046,729 at column 6, line 61 to column 7, line 26, incorporated
herein by reference.
[0128] In one embodiment, the substituent group X of the structure
(IV) can comprise a polymeric ester-containing group which is
terminated with hydroxyl or carboxylic acid functional groups. When
X is such a group, at least one polysiloxane can be the reaction
product of one or more polysiloxane polyols as described above, one
or more materials comprising at least one carboxylic acid
functional group, and one or more organic polyols. Nonlimiting
suitable examples of materials comprising at least one carboxylic
acid functional group include carboxylic acid group-containing
polymers well-known in the art, for example, carboxylic acid
group-containing acrylic polymers, polyester polymers, and
polyurethane polymers, such as those described in U.S. Pat. No.
4,681,811. Nonlimiting examples of suitable organic polyols include
those described above.
[0129] To form the at least one polysiloxane (A) containing epoxy
groups, at least one polysiloxane containing hydroxyl functional
groups as described above can be further reacted with a
polyepoxide. The polyepoxide can be an aliphatic or cycloaliphatic
polyepoxide or mixtures of any of the foregoing. Nonlimiting
examples of polyepoxides suitable for use include epoxy functional
acrylic copolymers prepared from at least one ethylenically
unsaturated monomer comprising at least one epoxy group, for
example glycidyl (meth)acrylate and allyl glycidyl ether, and one
or more ethylenically unsaturated monomers which have no epoxy
functionality. The preparation of such epoxy functional acrylic
copolymers is described in detail in U.S. Pat. No. 4,681,811 at
column 4, line 52 to column 5, line 50, incorporated herein by
reference. Reaction conditions and the ratio of reactants are
selected so as to form the desired functional groups.
[0130] In the embodiment of the present invention where the
boron-containing compound is formed from the at least one
functional group-containing polysiloxane (A) and the
boron-containing compound (B), the at least one polysiloxane (A)
can be reacted with the boron-containing compound (B) under
condensation reaction conditions well known in the art. For
example, mixing boric acid or a boric acid equivalent with a polyol
and removing water by distillation either directly or in
combination with a solvent. Other methods for preparing boric acid
esters can be found in "Kirk-Othmer Encyclopedia of Chemical
Technology" 4th edition, Vol 4, p 416; John Wiley and sons;
1992
[0131] Also, it should be understood, that the boron-containing
compound can be formed in situ. That is, the composition from which
one or both of the first and second polymeric layers is formed can
comprise boric acid and/or a borate ester and an active
hydrogen-containing component, such as a polymer or polysiloxane
comprising hydroxyl functional groups, as separate components. The
boron-containing compound can then be formed, for example, by
forming the condensate reaction product, i.e., the borate ester,
within the composition at ambient temperature or as the composition
undergoes a curing reaction at elevated temperatures. In this
instance, the composition can comprise the condensate reaction
product, and the boric acid and/or the borate ester and the active
hydrogen-containing component as three separate components.
[0132] In an alternative embodiment, the present invention provides
thermosetting compositions, for example, curable coating
compositions comprising (A) at least one polymer comprising at
least one reactive functional group, such as those described in
detail below, (B) at least one curing agent having at least one
functional group reactive with the functional groups of (A), and
(C) at least one compound selected from a borate, an aluminate, a
titanate, a zirconate, a silicate, a siloxane, a silane and
mixtures thereof, wherein each component is different. Typically,
the at least one compound (C) is selected from at least one of a
borate and an aluminate.
[0133] Examples of suitable borates are those discussed above.
Examples of titanates suitable for use in the compositions of the
present invention include titanium isopropoxide, isopropyl
triostearoyl titanate, dicyclo(dioct)pyrophosphato titanate,
tetraisopropyl di(dioctyl)phosphito titanate. Suitable aluminates
include aluminum alkoxides such as aluminum isoproxide, which is
typically employed, and aluminum acetylacetonate. Exemplary of a
suitable silicate is tetraethyl orthosilicate. Suitable siloxanes
include tetraisopropyldisiloxanes and tetramethylsiloxane. Suitable
silanes include tetramethyl silyl ethers. In one embodiment of the
present invention, a polysiloxane (a) comprising one or more
hydroxyl functional groups is reacted with an aluminum alkoxide
such as aluminum triisopropoxide.
[0134] In the multi-layer composite of the present invention, the
compound (C), which typically is selected from at least one of an
aluminum alkoxide or boron-containing compound such as those
described in detail above, is present in one or both of the first
and second polymeric layers in an amount sufficient to improve the
interlayer adhesion between the first and the second polymeric
layers. That is, when the compound (C) is present in one or both of
the polymeric layers, the delamination or adhesion loss, as
determined in accordance with ASTM-3359-97, method B, of the second
polymeric layer from the first polymer layer can be increased by
one or more numerical units of the rating scale specified in the
aforementioned method. As mentioned previously, one or both of the
first polymeric layer and the second polymeric layer can be formed
from a thermosetting composition. In one embodiment of the
invention, one or both of the first polymeric layer and the second
polymeric layer comprise a cured layer formed from a thermosetting
composition comprising (A) at least one film-forming polymer having
reactive functional groups; (B) at least one curing agent having
functional groups reactive with the functional groups of (A); and
(C) at least one of the aforementioned boron-containing compounds,
wherein the components are different.
[0135] When added to the other components that form the
thermosetting composition from which the curable composition from
which the first and/or the second polymeric layer is formed, the
adhesion promoter composition, usually a boron-containing compound,
(C) can be present in the composition in an amount sufficient to
provide an amount of elemental adhesion promoter component (1),
e.g., boron, present in the composition of at least 0.001 weight
percent, often at least 0.025 weight percent, usually at least 0.05
weight percent, and typically at least 0.10 weight percent, based
on total weight of the resin solids present in the composition.
Also, the adhesion promoter composition, usually a boron-containing
compound, (C), when added to the other components that form the
thermosetting composition from which the curable composition from
which the first and/or second polymeric layer is formed, can be
present in the composition in an amount sufficient to provide an
amount of elemental adhesion promoting component (1), usually
boron, present in the composition of less than 5 weight percent,
often less than 3 weight percent, usually less than 2.5 weight
percent, and typically less than 2 weight percent, based on total
weight of the resin solids present in the composition. The amount
of adhesion promoter composition, e.g., boron-containing compound,
(C) is present in the thermosetting composition in an amount
sufficient to provide an amount of elemental adhesion promoting
component (1), e.g., boron, present in the composition that can
range between any combination of these values inclusive of the
recited values.
[0136] As aforementioned, the thermosetting composition of the
present invention (which can comprise a curable coating
composition, comprises, in addition to the compound (C), at least
one film-forming polymer comprising at least one reactive
functional group (A), and at least one reactant, typically a curing
agent, (B) comprising at least one functional group which is
reactive with the functional group of (A). The at least one
film-forming polymer having reactive functional groups (A) can be
different from and in addition to the at least one curing agent
(B), and compound (C). The film-forming polymer (A) can have at
least one functional group reactive with the curing agent (B), and,
if applicable, the compound (C). In one embodiment, the at least
one reactive functional group-containing film-forming polymer (A)
can be selected from at least one of polyether polymers, polyester
polymers, acrylic polymers, silicon-based polymers, polyepoxide
polymers, and polyurethane polymers.
[0137] In a particular embodiment of the present invention, the
film-forming polymer (A) can comprise at least one reactive
functional group selected from a hydroxyl group, a carboxyl group,
an isocyanate group, a blocked isocyanate group, a primary amine
group, a secondary amine group, an amide group, a carbamate group,
a urea group, a urethane group, a vinyl group, an unsaturated ester
group, a maleimide group, a fumarate group, an anhydride group, a
hydroxy alkylamide group, and an epoxy group.
[0138] In another embodiment of the present invention, the
film-forming polymer (A) comprises at least one reactive functional
group selected from a hydroxyl group, a carbamate group, an epoxy
group, an isocyanate group, and a carboxyl group. In another
embodiment, the polymer comprises at least one reactive functional
group selected from a hydroxyl group, and a carbamate group.
[0139] The film-forming polymer (A) can comprise a mixture of any
of the foregoing reactive functional groups.
[0140] Film-forming polymers suitable for use as the at least one
reactive functional group-containing film-forming polymer (A) can
include any of a variety of functional polymers known in the art.
For example, suitable hydroxyl group-containing polymers can
include acrylic polyols, polyester polyols, polyurethane polyols,
polyether polyols, and mixtures thereof. In a particular embodiment
of the present invention, the film-forming polymer is an acrylic
polyol having a hydroxyl equivalent weight ranging from 1000 to 100
grams per solid equivalent, preferably 500 to 150 grams per solid
equivalent.
[0141] Suitable hydroxyl group and/or carboxyl group-containing
acrylic polymers can be prepared from polymerizable ethylenically
unsaturated monomers and are typically copolymers of (meth)acrylic
acid and/or hydroxylalkyl esters of (meth)acrylic acid with one or
more other polymerizable ethylenically unsaturated monomers such as
alkyl esters of (meth)acrylic acid including methyl (meth)acrylate,
ethyl (meth)acrylate, butyl (meth)acrylate and 2-ethyl
hexylacrylate, and vinyl aromatic compounds such as styrene,
alpha-methyl styrene, and vinyl toluene. As used herein,
"(meth)acrylate" and like terms is intended to include both
acrylates and methacrylates.
[0142] In a one embodiment of the present invention the acrylic
polymer can be prepared from ethylenically unsaturated,
beta-hydroxy ester functional monomers. Such monomers can be
derived from the reaction of an ethylenically unsaturated acid
functional monomer, such as monocarboxylic acids, for example,
acrylic acid, and an epoxy compound which does not participate in
the free radical initiated polymerization with the unsaturated acid
monomer. Examples of such epoxy compounds include glycidyl ethers
and esters. Suitable glycidyl ethers include glycidyl ethers of
alcohols and phenols such as butyl glycidyl ether, octyl glycidyl
ether, phenyl glycidyl ether and the like. Suitable glycidyl esters
include those which are commercially available from Shell Chemical
Company under the tradename CARDURA E; and from Exxon Chemical
Company under the tradename GLYDEXX-10. Alternatively, the
beta-hydroxy ester functional monomers can be prepared from an
ethylenically unsaturated, epoxy functional monomer, for example
glycidyl (meth)acrylate and allyl glycidyl ether, and a saturated
carboxylic acid, such as a saturated monocarboxylic acid, for
example isostearic acid.
[0143] Epoxy functional groups can be incorporated into the polymer
prepared from polymerizable ethylenically unsaturated monomers by
copolymerizing oxirane group-containing monomers, for example
glycidyl (meth)acrylate and allyl glycidyl ether, with other
polymerizable ethylenically unsaturated monomers, such as those
discussed above. Preparation of such epoxy functional acrylic
polymers is described in detail in U.S. Pat. No. 4,001,156 at
columns 3 to 6, incorporated herein by reference.
[0144] Carbamate functional groups can be incorporated into the
polymer prepared from polymerizable ethylenically unsaturated
monomers by copolymerizing, for example, the above-described
ethylenically unsaturated monomers with a carbamate functional
vinyl monomer such as a carbamate functional alkyl ester of
methacrylic acid. Useful carbamate functional alkyl esters can be
prepared by reacting, for example, a hydroxyalkyl carbamate, such
as the reaction product of ammonia and ethylene carbonate or
propylene carbonate, with methacrylic anhydride. Other useful
carbamate functional vinyl monomers include, for instance, the
reaction product of hydroxyethyl methacrylate, isophorone
diisocyanate, and hydroxypropyl carbamate; or the reaction product
of hydroxypropyl methacrylate, isophorone diisocyanate, and
methanol. Still other carbamate functional vinyl monomers may be
used, such as the reaction product of isocyanic acid (HNCO) with a
hydroxyl functional acrylic or methacrylic monomer such as
hydroxyethyl acrylate, and those described in U.S. Pat. No.
3,479,328, incorporated herein by reference. Carbamate functional
groups can also be incorporated into the acrylic polymer by
reacting a hydroxyl functional acrylic polymer with a low molecular
weight alkyl carbamate such as methyl carbamate. Pendant carbamate
groups can also be incorporated into the acrylic polymer by a
"transcarbamoylation" reaction in which a hydroxyl functional
acrylic polymer is reacted with a low molecular weight carbamate
derived from an alcohol or a glycol ether. The carbamate groups
exchange with the hydroxyl groups yielding the carbamate functional
acrylic polymer and the original alcohol or glycol ether. Also,
hydroxyl functional acrylic polymers can be reacted with isocyanic
acid to provide pendent carbamate groups. Likewise, hydroxyl
functional acrylic polymers can be reacted with urea to provide
pendent carbamate groups.
[0145] The polymers prepared from polymerizable ethylenically
unsaturated monomers can be prepared by solution polymerization
techniques, which are well-known to those skilled in the art, in
the presence of suitable catalysts such as organic peroxides or azo
compounds, for example, benzoyl peroxide or
N,N-azobis(isobutylronitrile). The polymerization can be carried
out in an organic solution in which the monomers are soluble by
techniques conventional in the art. Alternatively, these polymers
can be prepared by aqueous emulsion or dispersion polymerization
techniques which are well-known in the art. The ratio of reactants
and reaction conditions are selected to result in an acrylic
polymer with the desired pendent functionality.
[0146] Polyester polymers are also useful in the coating
compositions of the invention as the film-forming polymer. Useful
polyester polymers typically include the condensation products of
polyhydric alcohols and polycarboxylic acids. Suitable polyhydric
alcohols can include ethylene glycol, neopentyl glycol, trimethylol
propane, and pentaerythritol. Suitable polycarboxylic acids can
include adipic acid, 1,4-cyclohexyl dicarboxylic acid, and
hexahydrophthalic acid. Besides the polycarboxylic acids mentioned
above, functional equivalents of the acids such as anhydrides where
they exist or lower alkyl esters of the acids such as the methyl
esters can be used. Also, small amounts of monocarboxylic acids
such as stearic acid can be used. The ratio of reactants and
reaction conditions are selected to result in a polyester polymer
with the desired pendent functionality, i.e., carboxyl or hydroxyl
functionality.
[0147] For-example, hydroxyl group-containing polyesters can be
prepared by reacting an anhydride of a dicarboxylic acid such as
hexahydrophthalic anhydride with a diol such as neopentyl glycol in
a 1:2 molar ratio. Where it is desired to enhance air-drying,
suitable drying oil fatty acids may be used and include those
derived from linseed oil, soya bean oil, tall oil, dehydrated
castor oil, or tung oil.
[0148] Carbamate functional polyesters can be prepared by first
forming a hydroxyalkyl carbamate that can be reacted with the
polyacids and polyols used in forming the polyester. Alternatively,
terminal carbamate functional groups can be incorporated into the
polyester by reacting isocyanic acid with a hydroxy functional
polyester. Also, carbamate functionality can be incorporated into
the polyester by reacting a hydroxyl polyester with a urea.
Additionally, carbamate groups can be incorporated into the
polyester by a transcarbamoylation reaction. Preparation of
suitable carbamate functional group-containing polyesters are those
described in U.S. Pat. No. 5,593,733 at column 2, line 40 to column
4, line 9, incorporated herein by reference.
[0149] Polyurethane polymers containing terminal isocyanate or
hydroxyl groups also can be used as the polymer (d) in the coating
compositions of the invention. The polyurethane polyols or
NCO-terminated polyurethanes which can be used are those prepared
by reacting polyols including polymeric polyols with
polyisocyanates. Polyureas containing terminal isocyanate or
primary and/or secondary amine groups which also can be used are
those prepared by reacting polyamines including polymeric
polyamines with polyisocyanates. The hydroxyl/isocyanate or
amine/isocyanate equivalent ratio is adjusted and reaction
conditions are selected to obtain the desired terminal groups.
Examples of suitable polyisocyanates include those described in
U.S. Pat. No. 4,046,729 at column 5, line 26 to column 6, line 28,
incorporated herein by reference. Examples of suitable polyols
include those described in U.S. Pat. No. 4,046,729 at column 7,
line 52 to column 10, line 35, incorporated herein by reference.
Examples of suitable polyamines include those described in U.S.
Pat. No. 4,046,729 at column 6, line 61 to column 7, line 32 and in
U.S. Pat. No. 3,799,854 at column 3, lines 13 to 50, both
incorporated herein by reference.
[0150] Carbamate functional groups can be introduced into the
polyurethane polymers by reacting a polyisocyanate with a polyester
having hydroxyl functionality and containing pendent carbamate
groups. Alternatively, the polyurethane can be prepared by reacting
a polyisocyanate with a polyester polyol and a hydroxyalkyl
carbamate or isocyanic acid as separate reactants. Examples of
suitable polyisocyanates are aromatic isocyanates, such as
4,4'-diphenylmethane diisocyanate, 1,3-phenylene diisocyanate and
toluene diisocyanate, and aliphatic polyisocyanates, such as
1,4-tetramethylene diisocyanate and 1,6-hexamethylene diisocyanate.
Cycloaliphatic diisocyanates, such as 1,4-cyclohexyl diisocyanate
and isophorone diisocyanate also can be employed.
[0151] Examples of suitable polyether polyols include polyalkylene
ether polyols such as those having the following structural
formulas (VII) or (VIII): 3
[0152] wherein the substituent R is hydrogen or a lower alkyl group
containing from 1 to 5 carbon atoms including mixed substituents,
and n has a value typically ranging from 0.2 to 6 and m has a value
ranging from 8 to 100 or higher. Exemplary polyalkylene ether
polyols include poly(oxytetramethylene) glycols,
poly(oxytetraethylene) glycols, poly(oxy-1,2-propylene) glycols,
and poly(oxy-1,2-butylene) glycols.
[0153] Also useful are polyether polyols formed from oxyalkylation
of various polyols, for example, glycols such as ethylene glycol,
1,6-hexanediol, Bisphenol A, and the like, or other higher polyols
such as trimethylolpropane, pentaerythritol, and the like. Polyols
of higher functionality which can be utilized as indicated can be
made, for instance, by oxyalkylation of compounds such as sucrose
or sorbitol. One commonly utilized oxyalkylation method is reaction
of a polyol with an alkylene oxide, for example, propylene or
ethylene oxide, in the presence of an acidic or basic catalyst.
Specific examples of polyethers include those sold under the names
TERATHANE and TERACOL, available from E. I. Du Pont de Nemours and
Company, Inc.
[0154] Generally, the polymers having reactive functional groups
which are useful in the coating compositions of the invention have
a weight average molecular weight (Mw) typically ranging from 1000
to 20,000 preferably 1500 to 15,000 and more preferably 2000 to
12,000 as determined by gel permeation chromatography using a
polystyrene standard.
[0155] Hydroxyl and/or carbamate functional group-containing
polymers are typically employed.
[0156] Polyepoxides such as those described below with reference to
the curing agent (B), can also be used.
[0157] The polymer having reactive functional groups (A) can be
present in the thermosetting compositions in an amount of at least
2 percent by weight, usually at least 5 percent by weight, and
typically at least 10 percent by weight based on weight of total
resin solids in the coating composition. Also, the polymer having
reactive functional groups can be present in the thermosetting
compositions of the invention in an amount less than 80 percent by
weight, usually less than 60 percent by weight, and typically less
than 50 percent by weight based on weight of total resin solids in
the coating composition. The amount of the polymer (A) having
reactive functional groups present in the thermosetting
compositions of the present invention can range between any
combination of these values inclusive of the recited values.
[0158] As aforementioned, in addition to the functional
group-containing film-forming polymer (A) and the boron-containing
compound (C), the thermosetting composition of the present
invention further comprises at least one curing agent having
functional groups reactive with the functional groups of the
film-forming polymer (A) (and/or the adhesion promoter composition,
e.g. boron containing compound (C), where applicable).
[0159] Dependent upon the reactive functional groups of the
film-forming polymer (A)(and, optionally, the composition/compound
(C)), this curing agent can be selected from an aminoplast resin, a
polyisocyanate, a blocked isocyanate, a polyepoxide, a polyacid, an
anhydride, an amine, a polyol, and mixtures of any of the
foregoing. In one embodiment, the at least one curing agent (B) is
selected from an aminoplast resin and a polyisocyanate.
[0160] In another embodiment, the present invention is directed to
any composition as previously described wherein the curing agent
comprises an aminoplast resin. Aminoplast resins, which can
comprise phenoplasts, as curing agents for hydroxyl, carboxylic
acid, and carbamate functional group-containing materials are well
known in the art. Suitable aminoplast resins, such as, for example,
those discussed above, are known to those of ordinary skill in the
art. Aminoplasts can be obtained from the condensation reaction of
formaldehyde with an amine or amide. Nonlimiting examples of amines
or amides include melamine, urea, or benzoguanamine. Condensates
with other amines or amides can be used; for example, aldehyde
condensates of glycoluril, which give a high melting crystalline
product useful in powder coatings. While the aldehyde used is most
often formaldehyde, other aldehydes such as acetaldehyde,
crotonaldehyde, and benzaldehyde can be used.
[0161] The aminoplast resin contains imino and methylol groups and
in certain instances at least a portion of the methylol groups are
etherified with an alcohol to modify the cure response. Any
monohydric alcohol can be employed for this purpose including
methanol, ethanol, n-butyl alcohol, isobutanol, and hexanol.
[0162] Nonlimiting examples of aminoplasts include melamine-,
urea-, or benzoguanamine-formaldehyde condensates, in certain
instances monomeric and at least partially etherified with one or
more alcohols containing from one to four carbon atoms. Nonlimiting
examples of suitable aminoplast resins are commercially available,
for example, from Cytec Industries, Inc. under the trademark
CYMEL.RTM. and from Solutia, Inc. under the trademark
RESIMENE.RTM..
[0163] In another embodiment of the present invention, the curing
agent comprises an aminoplast resin which, when added to the other
components that form the thermosetting composition, is generally
present in an amount ranging from 2 weight percent to 65 weight
percent, can be present in an amount ranging from 5 weight percent
to 50 weight percent, and typically is present in an amount ranging
from 5 weight percent to 40 weight percent based on total weight of
resin solids present in the composition.
[0164] In yet another embodiment of the present invention, the at
least one reactant (B) comprises a polyisocyanate curing agent. As
used herein, the term "polyisocyanate" is intended to include
blocked (or capped) isocyanates as well as unblocked
(poly)isocyanates. The polyisocyanate can be an aliphatic or an
aromatic polyisocyanate, or a mixture of the foregoing two.
Diisocyanates can be used, although higher polyisocyanates such as
isocyanurates of diisocyanates are often used. Higher
polyisocyanates also can be used in combination with diisocyanates.
Isocyanate prepolymers, for example, reaction products of
polyisocyanates with polyols also can be used. Mixtures of
polyisocyanate curing agents can be used.
[0165] If the polyisocyanate is blocked or capped, any suitable
aliphatic, cycloaliphatic, or aromatic alkyl monoalcohol known to
those skilled in the art can be used as a capping agent for the
polyisocyanate. Other suitable capping agents include oximes and
lactams. When used, the polyisocyanate curing agent is typically
present, when added to the other components which form the coating
composition, in an amount ranging from 5 to 65 weight percent, can
be present in an amount ranging from 10 to 45 weight percent, and
often are present in an amount ranging from 15 to 40 percent by
weight based on the total weight of resin solids present in the
composition.
[0166] Other useful curing agents comprise blocked isocyanate
compounds such as, for example, the tricarbamoyl triazine compounds
described in detail in U.S. Pat. No. 5,084,541, which is
incorporated by reference herein.
[0167] When used, the blocked polyisocyante curing agent can be
present, when added to the other components in the composition, in
an amount ranging up to 20 weight percent, and can be present in an
amount ranging from 1 to 20 weight percent, based on the total
weight of resin solids present in the composition.
[0168] In one embodiment of the present invention, the curing agent
comprises both an aminoplast resin and a polyisocyanate.
[0169] Anhydrides as curing agents for hydroxyl functional
group-containing materials also are well known in the art and can
be used in the present invention. Nonlimiting examples of
anhydrides suitable for use as curing agents in the compositions of
the invention include those having at least two carboxylic acid
anhydride groups per molecule which are derived from a mixture of
monomers comprising an ethylenically unsaturated carboxylic acid
anhydride and at least one vinyl co-monomer, for example, styrene,
alpha-methyl styrene, vinyl toluene, and the like. Nonlimiting
examples of suitable ethylenically unsaturated carboxylic acid
anhydrides include maleic anhydride, citraconic anhydride, and
itaconic anhydride. Alternatively, the anhydride can be an
anhydride adduct of a diene polymer such as maleinized
polybutadiene or a maleinized copolymer of butadiene, for example,
a butadiene/styrene copolymer. These and other suitable anhydride
curing agents are described in U.S. Pat. No. 4,798,746 at column
10, lines 16-50; and in U.S. Pat. No. 4,732,790 at column 3, lines
41-57, both of which are incorporated herein by reference.
[0170] Polyepoxides as curing agents for carboxylic acid functional
group-containing materials are well known in the art. Nonlimiting
examples of polyepoxides suitable for use in the compositions of
the present invention comprise polyglycidyl esters (such as
acrylics from glycidyl methacrylate), polyglycidyl ethers of
polyhydric phenols and of aliphatic alcohols, which can be prepared
by etherification of the polyhydric phenol, or aliphatic alcohol
with an epihalohydrin such as epichlorohydrin in the presence of
alkali. These and other suitable polyepoxides are described in U.S.
Pat. No. 4,681,811 at column 5, lines 33 to 58, which is
incorporated herein by reference.
[0171] Suitable curing agents for epoxy functional group-containing
materials comprise polyacid curing agents, such as the acid
group-containing acrylic polymers prepared from an ethylenically
unsaturated monomer containing at least one carboxylic acid group
and at least one ethylenically unsaturated monomer which is free
from carboxylic acid groups. Such acid functional acrylic polymers
can have an acid number ranging from 30 to 150. Acid functional
group-containing polyesters can be used as well. The
above-described polyacid curing agents are described in further
detail in U.S. Pat. No. 4,681,811 at column 6, line 45 to column 9,
line 54, which is incorporated herein by reference.
[0172] Also well known in the art as curing agents for isocyanate
functional group-containing materials are polyols, that is,
materials having two or more hydroxyl groups per molecule,
different from component (b) when component (b) is a polyol.
Nonlimiting examples of such materials suitable for use in the
compositions of the invention include polyalkylene ether polyols,
including thio ethers; polyester polyols, including polyhydroxy
polyesteramides; and hydroxyl-containing polycaprolactones and
hydroxy-containing acrylic copolymers. Also useful are polyether
polyols formed from the oxyalkylation of various polyols, for
example, glycols such as ethylene glycol, 1,6-hexanediol, Bisphenol
A and the like, or higher polyols such as trimethylolpropane,
pentaerythritol, and the like. Polyester polyols also can be used.
These and other suitable polyol curing agents are described in U.S.
Pat. No. 4,046,729 at column 7, line 52 to column 8, line 9; column
8, line 29 to column 9, line 66; and U.S. Pat. No. 3,919,315 at
column 2, line 64 to column 3, line 33, both of which are
incorporated herein by reference.
[0173] Polyamines also can be used as curing agents for isocyanate
functional group-containing materials. Nonlimiting examples of
suitable polyamine curing agents include primary or secondary
diamines or polyamines in which the radicals attached to the
nitrogen atoms can be saturated or unsaturated, aliphatic,
alicyclic, aromatic, aromatic-substituted-aliphatic,
aliphatic-substituted-aromatic, and heterocyclic. Nonlimiting
examples of suitable aliphatic and alicyclic diamines include
1,2-ethylene diamine, 1,2-porphylene diamine, 1,8-octane diamine,
isophorone diamine, propane-2,2-cyclohexyl amine, and the like.
Nonlimiting examples of suitable aromatic diamines include
phenylene diamines and the toluene diamines, for example,
o-phenylene diamine and p-tolylene diamine. These and other
suitable polyamines described in detail in U.S. Pat. No. 4,046,729
at column 6, line 61 to column 7, line 26, which is incorporated
herein by reference.
[0174] When desired, appropriate mixtures of curing agents may be
used. It should be mentioned that the thermosetting compositions
compositions can be formulated as a one-component composition where
a curing agent such as an aminoplast resin and/or a blocked
isocyanate compound such as those described above is admixed with
other composition components. The one-component composition can be
storage stable as formulated. Alternatively, compositions can be
formulated as a two-component composition where a polyisocyanate
curing agent such as those described above can be added to a
pre-formed admixture of the other composition components just prior
to application. The pre-formed admixture can comprise curing agents
such as aminoplast resins and/or blocked isocyanate compounds such
as those described above.
[0175] In another embodiment in which the thermosetting composition
can form a coating which is cured by actinic radiation or the
combination of actinic radiation and thermal energy, the components
from which the coating composition are formed further can comprise
at least one photoinitiator or photosensitizer which provides free
radicals or cations to initiate the polymerization process. Useful
photoinitiators have an adsorption in the range of 150 to 2,000 nm.
Non-limiting examples of useful photoinitiators include benzoin,
benzophenone, hydroxy benzophenone, anthraquinone, thioxanthone,
substituted benzoins such as butyl isomers of benzoin ethers,
.alpha.,.alpha.-diethoxyacetophenone,
.alpha.,.alpha.-dimethoxy-.alpha.-phenylacetophenone,
2-hydroxy-2-methyl-1-phenyl propane 1-one and 2,4,6 trimethyl
benzoyl diphenyl phosphine oxide.
[0176] In one embodiment, the present invention is directed to an
improved curable coating composition used to form a multi-layer
composite coating comprising at least a first coating layer formed
on at least a portion of a substrate, and a second coating layer
formed over at least a portion of the first coating layer, where
one or both the first coating layer and the second coating layer
are formed from the curable coating composition, and wherein in the
absence of a boron-containing compound, the first and second
coating layers have poor interlayer adhesion. The improvement
comprises the inclusion in the curable coating composition of a
boron-containing compound present in an amount sufficient to
improve the interlayer adhesion between the first coating layer and
the second coating layer.
[0177] The curable coating composition of the present invention can
comprise any of the foregoing thermosetting compositions described
above. Also, in the multi-layer composite coating wherein both of
the first and second coating layers are formed from the curable
composition, it should be understood that each of the first and
second coating layers can be formed from the same or different
curable coating compositions.
[0178] In a particular embodiment, the present invention is
directed to a multi-layer composite coating as discussed above
where one or both of the first coating layer and the second coating
layer are formed from a curable coating composition formed from
components comprising (A) an acrylic and/or a polyester polymer
having at least one reactive functional group selected from a
hydroxyl group, a carbamate group, and mixtures thereof; such as
any of those described above, (B) a curing agent selected from an
aminoplast resin and a polyisocyanate, such as those described
above, and (C) any of the foregoing adhesion promoter compositions,
e.g., boron-containing compounds, described above. In another
embodiment, the present invention is directed to a multi-layer
composite coating as discussed above where one or both of the first
coating layer and the second coating layer are formed from a
curable coating composition formed from components comprising (A)
an acrylic and/or a polyester polymer having at least one reactive
functional group selected from a hydroxyl group, a carbamate group,
and mixtures thereof; (B) a curing agent selected from an
aminoplast resin and a blocked isocyanate compound comprising a
tricarbamoyl triazine; and (C) any of the boron-containing
compounds described above.
[0179] The curable coating compositions of the present invention
can be solvent-based compositions, water-based compositions, in
solid particulate form, that is, a powder composition, in the form
of a powder slurry or an aqueous dispersion. The components of the
present invention used to form the compositions of the present
invention can be dissolved or dispersed in an organic solvent.
Nonlimiting examples of suitable organic solvents include alcohols,
such as butanol; ketones, such as methyl amyl ketone; aromatic
hydrocarbons, such as xylene; and glycol ethers, such as, ethylene
glycol monobutyl ether; esters; other solvents; and mixtures of any
of the foregoing.
[0180] In solvent based compositions, the organic solvent is
generally present in amounts ranging from 5 to 80 percent by weight
based on total weight of the resin solids of the components which
form the composition, and can be present in an amount ranging from
30 to 50 percent by weight. The compositions as described above can
have a total solids content ranging from 40 to 75 percent by weight
based on total weight of the resin solids of the components which
form the composition, and can have a total solids content ranging
from 50 to 70 percent by weight. Alternatively, the inventive
compositions can be in solid particulate form suitable for use as a
powder coating, or suitable for dispersion in a liquid medium such
as water for use as a powder slurry.
[0181] In a further embodiment, the compositions as previously
described further comprise a catalyst which is present during the
composition's formation. In one embodiment, the catalyst is present
in an amount sufficient to accelerate the reaction between at least
one reactive functional group of the at least one curing agent
and/or at least one reactive functional group of the at least one
film-forming polymer.
[0182] Nonlimiting examples of suitable catalysts include acidic
materials, for example, acid phosphates, such as phenyl acid
phosphate, and substituted or unsubstituted sulfonic acids such as
dodecylbenzene sulfonic acid or para-toluene sulfonic acid.
Non-limiting examples of suitable catalysts for reactions between
isocyanate groups and active hydrogen-containing materials, for
example, those comprising hydroxyl groups, include tin catalysts
such as dibutyl tin dilaurate and dibutyl tin oxide. Non-limiting
examples of epoxy acid base catalysts include tertiary amines such
as N,N'-dimethyldodecyl amine catalysts. In another embodiment, the
catalyst can be a phosphatized polyester or a phosphatized epoxy.
In this embodiment, the catalyst can be, for example, the reaction
product of phosphoric acid and a bisphenol A diglycidyl ether
having two hydrogenated phenolic rings, such as DRH-151, which is
commercially available from Shell Chemical Co. The catalyst can be
present, when added to the other components that form the
composition, in an amount ranging from 0.1 to 5.0 percent by
weight, and is typically present in an amount ranging from 0.5 to
1.5 percent by weight based on the total weight of resin solids
present in the composition.
[0183] In another embodiment, additional components can be present
during the formation of the compositions as previously described.
These additional components include, but are not limited to,
particles different from components (A), (B) and (C), for example,
silica in colloidal, fumed, or amorphous form, alumina or colloidal
alumina, titanium dioxide, cesium oxide, yttrium oxide, colloidal
yttria, zirconia, e.g., colloidal or amorphous zirconia, and
mixtures of any of the foregoing, flexibilizers, plasticizers,
surface active agents, thixotropic agents, rheology control
modifiers, anti-gassing agents, organic cosolvents, flow
controllers, hindered amine light stabilizers, anti-oxidants, UV
light absorbers, coloring agents or tints, and similar additives
conventional in the art, as well as mixtures of any of the
foregoing can be included in the composition. These additional
ingredients can be present, when added to the other components that
form the composition, in an amount up to 40 percent by weight based
on the total weight of resin solids present in the composition.
[0184] In one embodiment, the present invention is directed to a
multi-layer composite coating wherein the first curable coating
composition comprises a base coating composition and the second
curable composition comprises a top coating composition. In another
embodiment of the present invention, the base coating composition
comprises a substantially pigment-free coating composition and the
top coating composition comprises a substantially pigment-free top
coating composition. In an alternative embodiment of the present
invention, the base coating composition comprises a
pigment-containing coating composition and the top coating
composition comprises a pigment-containing composition. In another
embodiment of the present invention, the base coating composition
comprises a pigment-containing coating composition and the top
coating composition comprises a substantially pigment-free coating
composition. In another embodiment of the present invention, the
base coating composition comprises a substantially pigment-free
base coating composition and the top coating composition comprises
a pigment-containing coating composition.
[0185] As used herein, by "substantially pigment-free coating
composition" is meant a coating composition which forms a
transparent coating, such as a clearcoat in a multi-component
composite coating composition. Such compositions are sufficiently
free of pigment or particles such that the optical properties of
the resultant coatings are not seriously compromised. As used
herein, "transparent" means that the cured coating has a BYK Haze
index of less than 50 as measured using a BYK/Haze Gloss
instrument.
[0186] The pigment-containing coating compositions can be any of
the pigmented compositions commonly used in the coatings industry.
For example, the pigment-containing coating composition can
comprise a primer coating composition, such as a pigmented
thermosetting weldable primer coating composition, for example,
those commercially available under the tradename BONAZINC.RTM., an
electrodepositable coating composition such as ED-5000, a
primer-surfacer coating composition such as GPX45379, a
color-enhancing base coat such as HWB-9517, and ODCT-6373, all
available from PPG Industries, Inc. of Pittsburgh, Pa., or an
adhesive composition such as those used as automotive windshield
adhesives, for example BETASEAL 15625 available from Essex
Specialty Products.
[0187] Likewise, the pigment-free curable coating composition can
comprise any of the pigment-free coatings known in the art such as
those used as clear coats in color-plus-clear coating systems for
the automotive industry. Non-limiting examples include TKU1050AR,
ODCT-8000, and those available under the tradename DIAMONDCOAT.RTM.
and NCT.RTM., all commercially available from PPG Industries,
Inc.
[0188] In another embodiment, the present invention is directed to
multi-component composite coating compositions comprising a
basecoat deposited from a pigment-containing base coating
composition, which can comprise any of the aforementioned curable
coating compositions, and a topcoat deposited from any of the
coating compositions of the present invention previously described
above. In one embodiment, the present invention is directed to a
multi-component composite coating composition as previously
described, wherein the topcoating composition is transparent after
curing and is selected from any of the compositions previously
described. The components used to form the topcoating composition
in these embodiments can be selected from the coating components
discussed above, and additional components also can be selected
from those recited above. It should be understood that one or both
of the basecoating composition and the top coating composition can
be formed from the curable coating compositions of the present
invention.
[0189] The basecoat and transparent topcoat (i.e., clearcoat)
compositions used in the multi-component composite coating
compositions of the present invention in certain instances can be
formulated into liquid high solids coating compositions, that is,
compositions containing 40 percent, or greater than 50 percent by
weight resin solids. The solids content can be determined by
heating a sample of the composition to 105.degree. C. to
110.degree. C. for 1-2 hours to drive off the volatile material,
and subsequently measuring relative weight loss. As aforementioned,
although the compositions can be liquid coating compositions, they
also can be formulated as powder coating compositions.
[0190] Where the basecoat is not formed from a composition of the
present invention (but the topcoat is formed from a curable coating
composition of the present invention) the coating composition of
the basecoat in the color-plus-clear system can be any of the
compositions useful in coatings applications, particularly
automotive applications. The coating composition of the basecoat
can comprise a resinous binder and a pigment to act as the
colorant. Nonlimiting examples of resinous binders are acrylic
polymers, polyesters, alkyds, and polyurethanes.
[0191] The resinous binders for the basecoat can be organic
solvent-based materials such as those described in U.S. Pat. No.
4,220,679, note column 2, line 24 continuing through column 4, line
40, which portions are incorporated by reference. Also, water-based
coating compositions such as those described in U.S. Pat. Nos.
4,403,003, 4,147,679 and 5,071,904 can be used as the binder in the
basecoat composition. These U.S. patents are incorporated herein by
reference.
[0192] The basecoat composition can comprise one or more pigments
as colorants. Nonlimiting examples of suitable metallic pigments
include aluminum flake, copper bronze flake, and metal oxide coated
mica.
[0193] Besides the metallic pigments, the basecoat compositions can
contain nonmetallic color pigments conventionally used in surface
coatings such as, for example, inorganic pigments such as titanium
dioxide, iron oxide, chromium oxide, lead chromate, and carbon
black; and organic pigments such as phthalocyanine blue and
phthalocyanine green.
[0194] Optional ingredients in the basecoat composition can
comprise those which are well known in the art of formulating
surface coatings and can comprise surface active agents, flow
control agents, thixotropic agents, fillers, anti-gassing agents,
organic co-solvents, catalysts, and other customary auxiliaries,
Nonlimiting examples of these materials and suitable amounts are
described in U.S. Pat. Nos. 4,220,679; 4,403,003; 4,147,769; and
5,071,904, which patents are incorporated herein by reference.
[0195] The basecoat compositions can be applied to the substrate by
any conventional coating technique such as brushing, spraying,
dipping, or flowing. Spray techniques and equipment for air
spraying, airless spray, and electrostatic spraying in either
manual or automatic methods, known in the art can be used.
[0196] During application of the basecoat to the substrate, the
film thickness of the basecoat formed on the substrate can range
from 0.1 to 5 mils. In another embodiment, the film thickness of
the basecoat formed on the substrate can range 0.1 to 1 mils, and
can be 0.4 mils.
[0197] After forming a film of the basecoat on the substrate, the
basecoat can be cured or alternatively given a drying step in which
solvent is driven out of the basecoat film by heating or an air
drying period before application of the clearcoat. Suitable drying
conditions may depend on the particular basecoat composition, and
on the ambient humidity if the composition is water-borne, but a
drying time from 1 to 15 minutes at a temperature of 750 to
200.degree. F. (210 to 93.degree. C.) can be adequate.
[0198] The transparent or clear topcoat composition can be applied
to the basecoat by any conventional coating technique, including,
but not limited to, compressed air spraying, electrostatic
spraying, and either manual or automatic methods. The transparent
topcoat can be applied to a cured or to a dried basecoat before the
basecoat has been cured. In the latter instance, the two coatings
can then be heated to cure both coating layers simultaneously.
Typical curing conditions can range from 50.degree. F. to
475.degree. F. (10.degree. C. to 246.degree. F.) for 1 to 30
minutes. The clearcoating thickness (dry film thickness) can be 1
to 6 mils.
[0199] A second topcoat coating composition can be applied to the
first topcoat to form a "clear-on-clear" topcoat. The first topcoat
coating composition can be applied over the basecoat as described
above. The second topcoat coating composition can be applied to a
cured or to a dried first topcoat before the basecoat and first
topcoat have been cured. The basecoat, the first topcoat and the
second topcoat can then be heated to cure the three coatings
simultaneously.
[0200] It should be understood that the second transparent topcoat
and the first transparent topcoat coating compositions can be the
same or different provided that, when applied wet-on-wet, one
topcoat does not substantially interfere with the curing of the
other for example by inhibiting solvent/water evaporation from a
lower layer. Moreover, the first topcoat, the second topcoat or
both can be the curable coating composition of the present
invention. Alternatively, only one of the first topcoat and the
second topcoat is formed from the curable coating composition of
the present invention.
[0201] In this instance, the topcoat that does not comprise the
curable coating composition of the present invention can include
any of the crosslinkable coating compositions comprising at least
one thermosettable coating material and at least one curing agent.
Suitable waterborne clearcoats for this purpose are disclosed in
U.S. Pat. No. 5,098,947 (incorporated by reference herein) and are
based on water-soluble acrylic resins. Useful solvent borne
clearcoats are disclosed in U.S. Pat. Nos. 5,196,485 and 5,814,410
(incorporated by reference herein) and include polyepoxides and
polyacid curing agents. Suitable powder clearcoats for this purpose
are described in U.S. Pat. No. 5,663,240 (incorporated by reference
herein) and include epoxy functional acrylic copolymers and
polycarboxylic acid curing agents.
[0202] Typically, after forming the first topcoat over the
basecoat, the first topcoat is given a drying step in which solvent
is driven out of the film by heating or, alternatively, an air
drying period or curing step before application of the second
topcoat. Suitable drying conditions will depend on the particular
first topcoat composition, and on the ambient humidity if the
composition is water-borne, but, in general, a drying time from 1
to 15 minutes at a temperature of 75.degree. F. to 200.degree. F.
(21.degree. C. to 93.degree. C.) will be adequate.
[0203] The film-forming composition of the present invention when
employed as a second topcoat coating composition can be applied as
described above for the first topcoat by any conventional coating
application technique. Curing conditions can be those described
above for the topcoat. The second topcoating dry film thickness can
range from 0.1 to 3 mils (7.5 micrometers to 75 micrometers).
[0204] It should be mentioned that the coating compositions of the
present invention can be advantageously formulated as a "monocoat",
that is a coating which forms essentially one coating layer when
applied to a substrate. The monocoat coating composition can be
pigmented. Nonlimiting examples of suitable pigments include those
mentioned above. When employed as a monocoat, the coating
compositions of the present invention can be applied (by any of the
conventional application techniques discussed above) in two or more
successive coats, and, in certain instances can be applied with
only an ambient flash period between coats. The multi-coats when
cured can form essentially one coating layer.
[0205] In one embodiment, the present invention is directed to a
method of repairing a multi-layer composite coating comprising a
base coat formed on a substrate from a film-forming base coating
composition and a first top coat deposited over at least a portion
of the base coat, the first top coat formed from a first
film-forming top coating composition comprising any of the
foregoing coating compositions, the method comprising locating an
area of the composite coating which is flawed, and applying a
repair top coat film-forming composition to the flawed area after
the flawed area has been prepared for repairing. The repair topcoat
film-forming composition can comprise a film-forming composition
which is the same or different from the first topcoat film-forming
composition. The flawed area can be any coating blemish that cannot
be polished out, for example dirt particles in the coating surface.
The flawed area typically can be abraded or sanded to remove such
coating blemishes. In a repair carried out in accordance with the
method of the present invention, the first top coating can provide
excellent intercoat adhesion with the subsequently applied repair
top coating.
[0206] The coating compositions of the present invention can
provide cured coatings having excellent intercoat or interlayer
adhesion to subsequently applied coating layers. For example, any
of the aforementioned substantially pigment-free coating
compositions can be applied as a transparent clearcoat in a
color-plus-clear coating system as discussed above. In the event of
damage to the cured coating system causing a surface defect, it may
be necessary to prepare the damaged area for repair with a
subsequently applied clear coat composition. The coating
compositions of the present invention can provide excellent
intercoat adhesion between the first clear coat layer and the
subsequently applied repair clear coat layer. Likewise, when used
as a top coat composition, the coating compositions of the present
invention also provide excellent interlayer adhesion between the
cured top coat and a subsequently applied windshield adhesive
without the intervening step of applying an adhesion promoting
primer.
[0207] Illustrating the invention are the following examples that
are not to be considered as limiting the invention to their
details. All parts and percentages in the examples, as well as
throughout the specification, are by weight unless otherwise
indicated.
EXAMPLES
[0208] Example AA describes the preparation of a polysiloxane
polyol. Examples BB and CC describe the preparation of a carbamate
functional acrylic resin and a carbamate functional polyester
resin, respectively. Examples A through J describe the preparation
of various adhesion promoters used in the compositions of the
present invention. Coating composition Examples 1 through 9
describe the preparation of one-component clearcoating
compositions. Examples 10 through 13 describe the preparation of
clearcoating compositions based on epoxy-containing acrylic resins
in conjunction with acid functional curing agents. Examples 14
through 23 describe the preparation of two-component clearcoating
compositions. Examples 24 and 25 describe the preparation of
basecoating compositions. Examples 26 through 30 describe the
preparation of clearcoating compositions based on carbamate
group-containing resins, and Examples 31 through 33 describe the
preparation of powder clearcoating compositions.
Resin Compositions Example AA
Polysiloxane Polyol
[0209] This example describes the preparation of a polysiloxane
polyol which was subsequently used to form respective silica
dispersions of Examples A and B, and the adhesion promoters used in
the thermosetting compositions of the present invention. The
polysiloxane polyol was a product of the hydrosilylation of a
reactive silicone fluid having an approximate degree of
polymerization of 3 to 7, i.e., (Si--O).sub.3 to (Si--O).sub.7. The
polysiloxane polyol was prepared from a proportionately scaled-up
batch of the following mixture of ingredients in the ratios
indicated:
1 Equivalent Parts By Weight Ingredients Weight Equivalents
(kilograms) Charge I: Trimethylolpropane 174.0 756.0 131.54
monoallyl ether Charge II: MASILWAX BASE.sup.1 156.7.sup.2 594.8
93.21 Charge III: Chloroplatinic acid 10 ppm Toluene 0.23
Isopropanol 0.07 .sup.1Polysiloxane-containing silicon hydride,
commercially available from BASF Corporation. .sup.2Equivalent
weight based on mercuric bichloride determination.
[0210] To a suitable reaction vessel equipped with a means for
maintaining a nitrogen blanket, Charge I and an amount of sodium
acetate equivalent to 20 to 25 ppm of total monomer solids was
added at ambient conditions and the temperature was gradually
increased to 75.degree. C. under a nitrogen blanket. At that
temperature, about 5.0% of Charge II was added under agitation,
followed by the addition of Charge III, equivalent to 10 ppm of
active platinum based on total monomer solids. The reaction was
then allowed to exotherm to 95.degree. C. at which time the
remainder of Charge II was added at a rate such that the
temperature did not exceed 95.degree. C. After completion of this
addition, the reaction temperature was maintained at 95.degree. C.
and monitored by infrared spectroscopy for disappearance of the
silicon hydride absorption band (Si--H, 2150 cm.sup.-1).
Example BB
Carbamate Functionalacrylic Polymer
[0211] This example describes the preparation of a carbamate
functional acrylic used in the clearcoating compositions of
Examples 26-30 described below. The polymer was prepared from the
following ingredients:
2 Ingredient Weight in Parts Acrylic polymer.sup.1 1614.4 Methyl
carbamate 240.3 Butyl stannoic acid 3.05 Triphenyl phosphite 3.05
.sup.1Prepared from hydroxypropyl acrylate, butyl methacrylate and
alpha methyl styrene dimer, 90% solids in DOWANOL .RTM. PM.
[0212] A suitable reactor equipped with a thermocouple, overhead
stirrer, nitrogen inlet and a reflux condenser was charged with the
above ingredients. The reaction mixture was heated to a temperature
of 145.degree. C. under a nitrogen blanket. At this temperature,
reflux was observed. The reaction mixture was held at reflux for
one hour. After the hold period was complete, the reflux condenser
was removed, and the reactor equipped for distillation (short
column, still head, thermocouple, and receiver) at atmospheric
pressure. Distillate began to come over at 139.degree. C. The
temperature of the reaction was gradually raised to 151.degree. C.
to maintain a steady rate of distillation. At this point, 87 parts
of distillate had been collected. The reaction mixture was then
cooled to 140.degree. C. and equipped for simple vacuum
distillation (still head, vacuum adapter, receiver flask).
Distillation was resumed under reduced pressure; the pressure
inside the reactor was gradually reduced to maintain distillation
until a reactor pressure of 60-mm Hg was attained. When the
distillation was essentially stopped, the reaction mixture was
sampled and the hydroxyl value found to be 36. The additional
distillate collected totaled 158 parts. The contents of the reactor
were then diluted with 410 parts of ethyl 3-ethoxypropionate and
410 parts DOWANOL PM. The final resin solution was found to have
solids content of 64.5%, determined at 110.degree. C. for one hour.
The weight average molecular weight was about 10,400 and the number
average molecular weight was about 2,900, as determined by gel
permeation chromatography using a polystyrene standard.
Example CC
Carbamate Functional Polyester
[0213] This example describes the preparation of a
carbamate-functional polyester resin used in the carbamate
containing clearcoating compositions of the present invention. The
carbamate functional polyester resin was prepared from the
following ingredients:
3 Ingredient Weight in Parts Polyester.sup.1 6916.4 Methyl
carbamate 1081.4 Butyl stannoic acid 14.4 Triphenyl phosphite 14.4
DOWANOL PM 1297.7 .sup.1Polyester polymer prepared from
2,2,4-trimethyl-1,3-pentanediol/trimethylol propane/neopentyl
glycol/hexahydrophthalic anhydride in a 22.7:10.6:17.5:49.2 weight
ratio, 100% solids.
[0214] A suitable reactor was charged with the above ingredients
and equipped with a thermocouple, overhead stirrer, nitrogen inlet
and a reflux condenser. The mixture was heated to a temperature of
141.degree. C. under a nitrogen blanket. At this temperature reflux
was observed. The reaction mixture was held at reflux for one hour.
After the hold period was complete, the reflux condenser was
removed, and the reactor equipped for distillation (short column,
still head, thermocouple, and receiver) at atmospheric pressure.
Distillate began to come over at 132.degree. C. The temperature of
the reaction was gradually raised to 151.degree. C. to maintain a
steady rate of distillation. At this point 422 parts of distillate
had been collected. The reaction mixture was then cooled to
145.degree. C. and equipped for simple vacuum distillation (still
head, vacuum adapter, receiver flask). Distillation was resumed
under reduced pressure; the pressure inside the reactor was
gradually reduced to maintain distillation until a reactor pressure
of 60-mm Hg was attained. When the distillation was essentially
stopped, the reaction mixture was sampled and the hydroxyl value
found to be acceptable (32.6). The additional distillate collected
totaled 1007 parts. The contents of the reactor were cooled and
then diluted with 1295 parts of DOWANOL PM and 1648 parts of
DOWANOL PM Acetate. The final resin solution was found to have a
solids content of 69.5%, determined at 110.degree. C. for one hour,
a weight average molecular weight of about 2,500 and a number
average molecular weight of about 1,200, as determined by gel
permeation chromatography using a polystyrene standard.
Silica Dispersions
Example A
[0215] This example describes the preparation of a colloidal silica
dispersion used as a component in the thermosetting compositions of
the present invention. The colloidal silica dispersion was prepared
as follows. A suitable reaction vessel was equipped for vacuum
distillation and flushed with N.sub.2. To the reaction flask was
added 3150 g of the polysiloxane polyol of Example M described
above, 4500 g of ORGANOSILICASOL.TM. MT-ST colloidal silica (which
is commercially available from Nissan Chemicals) and 1440 g of
methyl amyl ketone. The mean particle size of the silica particles
was about 10-20 nanometers, as disclosed at
http//www.snowtex.com/organo types.html (Jun. 2, 2000), which is
incorporated by reference herein. The resulting mixture was vacuum
distilled at 25.degree. C. for a period of 8 hours.
Example B
[0216] This example describes the preparation of a colloidal silica
dispersion used as a component in the thermosetting compositions of
the present invention. The colloidal silica dispersion was prepared
as follows. A 4-neck reaction flask equipped for vacuum
distillation was flushed with N.sub.2. To the reaction flask was
added 1501.4 g of the polysiloxane tetrol described above, 3752.9 g
of ORGANOSILICASOL.TM. MT-ST colloidal silica (which is
commercially available from Nissan Chemicals) and 900.6 g of methyl
amyl ketone. The resulting mixture was vacuum distilled at 70 mm Hg
and 31.degree. C.
Adhesion Promoter Compositions
[0217] The following Examples C through H describe the preparation
of various adhesion promoting compositions used in the coating
compositions of the present invention. Each adhesion promoting
composition was prepared as described below.
Example C
[0218] A four-neck reaction flask equipped with stirrer,
temperature probe, Dean Stark trap and reflux condenser was flushed
with N2. The following materials were charged to the flask and
blended under agitation: 180.4 g of the polysilxoane polyol of
Example AA, 300.9 g of isopropyl alcohol and 25.8 g of boric acid.
The mixture was heated to reflux at a temperature of 79.degree. C.,
and 200 ml of solvent was removed over 0.25 hours. The resulting
material was cooled and measured to have 49.8% solids and contained
3.0% water.
Example D
[0219] A four-neck reaction flask equipped with stirrer,
temperature probe, Dean Stark trap and reflux condenser was flushed
with N.sub.2. The following materials were charged to the flask and
blended under agitation: 3241.4 g of the polysiloxane polyol of
Example AA, 5415.3 g of isopropyl alcohol and 463.9 g of boric
acid. The mixture was heated to reflux at a temperature of
73.degree. C., and 3607.7 g of solvent was removed over a period of
1.5 hours. The resulting material was cooled and measured to have
56.0% solids and contained 2.5% water.
Example E
[0220] A four-neck reaction flask equipped with stirrer,
temperature probe, Dean Stark trap and reflux condenser was flushed
with N.sub.2. The following materials were charged to the flask and
blended under agitation: 180.3 g of polysiloxane polyol of Example
M, 300.7 g of isopropyl alcohol and 25.8 g of boric acid. The
mixture was heated to reflux at a temperature 79.degree. C., and
200 ml of solvent was removed over a period of 0.25 hours. The
resulting material was cooled and measured to have 49.5% solids and
contained 3.0% water.
Example F
[0221] A four-neck reaction flask equipped with stirrer,
temperature probe, Dean Stark trap and reflux condenser was flushed
with N.sub.2. The following materials were charged to the flask and
blended under agitation: 1575.5 g Dowanol PM, and 144.8 g of boric
acid. The mixture was heated to reflux at a temperature of
110.degree. C., and held for a period of 2 hours. Thereafter, 632.3
g of solvent was removed over a period of 0.5 hours. The resulting
material was cooled and measured to have 11.2% solids and contained
5.0% water.
Example G
[0222] A four-neck reaction flask equipped with stirrer,
temperature probe, Dean Stark trap and reflux condenser was flushed
with N.sub.2. The following ingredients were charged to the flask
and blended under agitation: 454.7 g of acrylic polyol (prepared
from 14.5% butyl acrylate, 14.5% butyl methacrylate, 27.6%
isobornyl methacrylate, 22.6% hydroxypropyl methacrylate, 20.4%
hydroxyethyl methacrylate, and 0.4% acrylic acid, having a resin
solids of 69.7%, Mw 3227 and hydroxyl value of 101), 97.2 g of
isopropyl alcohol and 2.06 g of boric acid. The mixture was heated
to reflux at a temperature of 93.degree. C., and held for a period
of 1 hour. Thereafter, 62 g of solvent was removed over a period of
0.25 hours. The resulting material was cooled and measured 69.3%
solids and contained 0.1% water.
Example H
[0223] A four-neck reaction flask equipped with stirrer,
temperature probe, Dean Stark trap and reflux condenser was flushed
with N.sub.2. The following materials were charged to the flask and
blended under agitation: 360.5 g of the polysiloxane polyol of
Example AA, 601.7 g of isopropyl alcohol and 13.6 g of aluminum
isopropoxide (available from Aldrich Chemical Co.). The mixture was
heated to reflux at a temperature of 81.degree. C., and,
thereafter, 401.8 g of solvent was removed over a period of 1 hour.
The resulting material was cooled and measured to have 53.32%
solids
Example I
[0224] A four-neck reaction flask equipped with stirrer,
temperature probe, Dean Stark trap and reflux condenser was flushed
with N.sub.2. The following materials were charged to the flask and
blended under agitation: 3242.1 g of the polysiloxane polyol of
Example AA, 5411.2 g of isopropyl alcohol and 463.9 g of boric
acid. The mixture was heated to reflux at a temperature of
72.degree. C., and 3674.3 g of solvent was removed over a period of
2 hours. The resulting material was cooled and measured 56.13%
solids and contained 2.5% water.
Thermosetting Coating Compositions One Component Clearcoating
Compositions
Example 1
[0225] This example describes the preparation of a resinous binder
pre-mix used in the one-package thermosetting coating compositions
of Examples 4-6 below. Each of the ingredients was added
sequentially and mixed under mild agitation.
4 Parts by weight Solid weight Ingredient (grams) (grams) Methyl
n-amyl ketone 18.0 -- Butyl Cellosolve .RTM. acetate.sup.1 18.0 --
Butyl Carbitol .RTM. acetate.sup.2 4.0 -- TINUVIN .RTM. 384.sup.3
1.58 1.50 TINUVIN .RTM. 400.sup.4 1.76 1.50 TINUVIN .RTM. 292.sup.5
0.40 0.40 TINUVIN .RTM. 123.sup.6 0.40 0.40 Silica dispersion of
Example A 13.2 10.0 LUWIPAL 018.sup.7 41.1 30.0 TACT.sup.8 9.4 5.0
Polybutyl acrylate.sup.9 0.50 0.30 Blocked acid catalyst.sup.10
2.50 1.00 .sup.12-Butoxyethyl acetate solventcommercially available
from Union Carbide Corp. .sup.22-(2-Butoxyethoxy) ethyl acetate
commercially available from Union Carbide Corp. .sup.3Substituted
benzotriazole UV light stabilizer commercially available from Ciba
Specialty Chemicals Corp. .sup.4Substituted triazine UV light
stabilizer commercially available from Ciba Specialty Chemicals
Corp. .sup.5Sterically hindered amine light stabilizer commercially
available from Ciba Specialty Chemicals Corp.
.sup.6Bis-(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate
hindered aminoether light stabilizer available from Ciba Specialty
Chemicals Corp. .sup.7High imino, butylated melamine formaldehyde
resin commercially available from BASF Corp. .sup.8Tris (alkyl
carbamoyl) triazine available from Cytec Industries, Inc. The alkyl
substituent was mixed methyl and butyl. .sup.9A flow control agent
having a Mw of about 6700 and a Mn of about 2600 made in xylene at
62.5% solids available from E.I. duPont de Nemours and Company.
.sup.10Dodecyl benzene sulfonic acid solution, blocked with
diisopropanol amine to 91% total neutralization, 40 percent in
ethanol.
Example 2
[0226] This example describes the preparation of a resinous binder
pre-mix used in the one-package thermosetting coating composition
of Examples 7-9 described below. Each of the ingredients was added
sequentally and mixed under mild agitation.
5 Parts by weight Solid weight Ingredient (grams) (grams) Methyl
n-amyl ketone 16.0 -- Butyl Cellosolve .RTM. acetate 16.0 -- Butyl
Carbitol .RTM. acetate 3.50 -- TINUVIN .RTM. 928.sup.1 3.00 3.00
TINUVIN .RTM. 292 0.40 0.40 Silica Dispersion of 10.3 7.0 Example B
RESIMENE .RTM. 757.sup.2 41.2 40.0 Polybutyl acrylate 0.50 0.30
Blocked acid catalyst 2.50 1.00
.sup.12-(2H-Benzotriazol-2y1)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetra-
methylbutyl)phenol UV absorber available from Ciba Specialty
Chemicals Corp. .sup.2Methylated and butylated
melamine-formaldehyde resin available from Cytec Industries,
Inc.
Example 3
[0227] This example describes the preparation of a resinous binder
pre-mix used in the preparation of thermosetting coating
compositions of Examples 7-9 described below. The resins were
admixed and blended under mild agitation.
6 Parts by Solid weight Ingredient weight (grams) (grams)
Carbamoylated acrylic.sup.1 44.4 28.0 Carbamoylated polyester.sup.2
38.9 28.0 .sup.1(58% butyl methacrylate/40% hydroxypropyl
acrylate/2% methyl styrene dimer) 64% solids in a solvent blend of
(50% DOWANOL PM/50% propanoic acid, 3-ethoxy ethyl ester), 75%
carbamoylated with methyl carbamate. .sup.2(10.6% trimethylol
propane/22.7% 2,2,4-trimethyl-1,3-pentanediol/17- .5% neopentyl
glycol/49.2% hexahydrophthalic anhydride) 69% solids in a solvent
blend of (44% Dowanol PM/56% Dowanol PM Acetate) 75% carbamoylated
with methyl carbamate.
[0228] The preparation of various one-package thermosetting coating
compositions are described below in the following Tables 1 and 2.
The amounts listed are the total parts by weight in grams and the
amount within parenthesis are percentages by weight based on weight
of solids. Each component was mixed sequentially with agitation.
Comparative coating compositions which do not contain a
boron-containing compound are indicated using an "*".
7TABLE 1 Ingredient Example 4* Example 5 Example 6 Example 1
pre-mix 110.8 (50.1) 110.8 (50.1) 110.8 (50.1) Acrylic resin.sup.1
89.9 (58.0) 88.4 (57.0) 83.7 (54.0) Siloxane Borate of -- 2.01
(1.00) 8.0 (4.00) Example C Reduction: Methyl n-amyl ketone 5.4
4.79 3.07 Butyl Cellosolve .RTM. 5.4 4.79 3.07 acetate Butyl
Carbitol .RTM. acetate 1.2 1.06 0.68 Spray viscosity.sup.2 (sec)
28.4 28.2 28.1 Paint temperature (.degree. F.) 73.3 73.5 73.1
Theory % Solids.sup.3 50.8 51.0 51.6 .sup.1Acrylic resin (30%
styrene, 19.9% hydroxyethyl methacrylate, 28.7% CarduraE (available
from Shell Chemical Co.), 9.5% acrylic acid, and 12% ethylhexyl
acrylate) at 65% solids in SOLVESSO 100 (available from Exxon
Chemicals America), prepared in Example A of U.S. Pat. No.
5,965,670. .sup.2Viscosity measured in seconds with a #4 FORD
efflux cup at ambient temperature. .sup.3Theory % Solids of a
coating is determined by taking the solid weight of the coating
formulation divided by the sum of the parts by weight of the
coating formulation and the reducing solvent weight
[0229]
8TABLE 2 Ingredient Example 7* Example 8 Example 9 Example 2
pre-mix 93.4 (51.7) 93.4 (51.7) 93.4 (51.7) Example 3 pre-mix 83.3
(56.0) 81.8 (55.0) 77.4 (52.0) Siloxane Borate of -- 1.79 (1.00)
7.1 (4.00) Example D Methyl n-amyl ketone 2.00 -- -- Butyl
Cellosolve .RTM. 2.00 -- -- acetate Butyl Carbitol .RTM. acetate
0.50 -- -- Reduction Information: Methyl n-amyl ketone 3.03 4.7
3.83 Butyl Cellosolve .RTM. 3.03 4.7 3.83 acetate Butyl Carbitol
.RTM. acetate 0.67 1.04 0.85 Spray viscosity.sup.1 (sec) 28.4 28.7
28.1 Paint temperature (.degree. F.) 72.4 72.3 72.0 Theory %
Solids.sup.2 57.3 57.5 57.8 .sup.1Viscosity measured in seconds
with a #4 FORD efflux cup at ambient temperature. .sup.2Theory %
Solids of a coating is determined by taking the solid weight of the
coating formulation divided by the sum of the parts by weight of
the coating formulation and the reducing solvent weight.
[0230] Testing
[0231] The film forming compositions of Examples 4-9 were spray
applied to a pigmented basecoat to form color-plus-clear composite
coatings over primed electrocoated steel panels. The panels used
were cold rolled steel panels (size 4 inches.times.12 inches (10.16
cm by 30.48 cm)). The steel panels for Examples 4-6 were coated
with ED5000 electrocoat, available from PPG Industries, Inc, and
SUPERMAR primer, available from Herberts/DuPont. The ED5000
electrocoat test panels are available as APR22986 from ACT
Laboratories, Inc. of Hillsdale, Mich. Examples 7-9 utilized steel
panels that were coated with ED5240 electrocoat and FCP6579 primer,
both available from PPG Industries, Inc. The test panels are
available as APR40017 from ACT Laboratories, Inc. of Hillsdale,
Mich.
[0232] The basecoat used for Examples 4-6 was Nero Vulcano UR806/A,
black pigmented solvent-based acrylic/melamine basecoat, available
from PPG Industries, Inc. Examples 7-9 used ODCT6373 Ebony Black, a
black pigmented solvent-based acrylic/melamine basecoat, available
from PPG Industries, Inc.
[0233] The Nero Vulcano UR806/A basecoat was automated spray
applied in one coat to the electrocoated and primed steel panels at
ambient temperature (about 70.degree. F. (21.degree. C.)). A dry
film thickness of about 0.5 to 0.7 mils (about 13 to 18
micrometers) was targeted. After the basecoat application, a ninety
second air flash at ambient temperature was given before applying
the clearcoat. The ODCT6373 Ebony Black basecoat was automated
spray applied in two coats to the electrocoated and primed steel
panels at ambient temperature (about 70.degree. F. (21.degree.
C.)). A ninety second air flash at ambient temperature was given
between the two basecoat applications. A dry film thickness of
about 0.6 to 0.8 mils (about 15 to 20 micrometers) was targeted.
After the second basecoat application, a ninety second air flash at
ambient temperature was given before applying the clearcoat.
[0234] The clear coating compositions of Examples 4-9 were each
automated spray applied to a basecoated panel at ambient
temperature in two coats with a ninety second ambient flash between
applications. Examples 4-6 were targeted for a 1.5 to 1.7 mils
(about 38 to 43 micrometers) dry film thickness, and Examples 7-9
were targeted for a 1.7 to 1.9 mils (about 43 to 48 micrometers)
dry film thickness. All coatings were allowed to air flash at
ambient temperature for ten minutes. Panels prepared from each
coating were baked for thirty minutes at 285.degree. F.
(141.degree. C.) to fully cure the coating(s). The panels were
baked in a horizontal position.
[0235] To test for recoat adhesion, an original basecoated and
clearcoated panel, as described above, was given another layer of
basecoat and clearcoat or clearcoat only. Examples 4-6 were
recoated with Nero Vulcano UR806/A and Examples 4-6, depending on
the respective original panel. Examples 7-9 were recoated with
ODCT6373 Ebony Black and Examples 7-9, depending on the respective
original panel. For example, an Example 4 clearcoat over Nero
Vulcano UR806/A original (prepared above) was recoated with Nero
Vulcano UR806/A and Example 4 clearcoat. Half of an original panel
from each clear coating was basecoated and clearcoated and the
other half of the panel was clearcoated only. To recoat the panels
half and half, the bottom halves of the original panels were
covered with aluminum foil and then the respective basecoats were
automated spray applied as described above. The foil was removed,
resulting in an original panel with the upper half coated in
basecoat and the bottom half still with only the original coating
layers. The respective clearcoat was then automated spray applied
to the entire panel as described above. The resulting panels were
half coated in basecoat/clearcoat from the original spray
application and another layer of basecoat/clearcoat from the recoat
spray application (B/C//B/C). The other half of the resulting panel
was coated in basecoat/clearcoat from the original spray
application and another layer of clearcoat from the recoat spray
application (B/C//C).
[0236] Test results for the coatings are reported below in Table 3.
As mentioned above the coating compositions of Examples 4-6 were
applied over Nero Vulcano UR806/A basecoat and Examples 7-9 were
applied over ODCT6373 Ebony Black basecoat.
9TABLE 3 Adhesion Promoter (B) Elemental Windshield Weight %
Adhesion.sup.3 Example on Resin 20.degree. Recoat Adhesion.sup.2 (%
cohesive # Solids Gloss.sup.1 B/C//B/C B/C//C failure) 4* 0 91 0 td
0 td -- 5 0.02 91 2/3 0 -- 6 0.08 91 4+ 4 -- 7* 0 86 2+ 0 0 8 0.02
86 5- 3+ 100 9 0.08 84 5 5 100 .sup.120.degree. gloss was measured
with a Statistical Novo-Gloss 20.degree. gloss meter, available
from Paul N. Gardner Company, Inc. .sup.2Recoat adhesion tests the
adhesion of the recoat layer (either basecoat/clearcoat or
clearcoat only) to the original layers
(steel/electrodeposition/primer/basecoat/clearcoat). A multi-blade
claw with 2.0 mm spaced teeth (blade and handle/blade holder are
available from Paul N. Gardner Company, Inc.) was used to scribe
the cured coating. Two sets of scribes were made by scribing the
second set on top of and perpendicular to the first set. Detached
flakes and # ribbons of coating were wiped off the panel and
strapping tape (3M #898 available from Minnesota, Mining and
Manufacturing Co.-3M) was smoothed firmly over the crosshatch
marking. Within 90 seconds of application, the tape was removed in
one continuous motion directed toward the tester and as parallel to
the panel as possible. The scribed area was inspected and rated for
removal of the recoat layer to the substrate according to the
following scale: 5 = The edges of the cuts are completely smooth
and none of the lattice squares is detached. 4 = Small flakes of
coating are detached at intersections. Less than five percent of
the area is affected. 3 = Small flakes of the coating are detached
along edges and at intersections of cuts. The area affected is five
to fifteen percent of the lattice. 2 = The coating has flaked along
the edges and on parts of the squares. The area affected is fifteen
to thirty-five percent of the lattice. 1 = The coating has flaked
along the edges of cuts in large ribbons and whole squares have
detached. The area affected is thirty-five to sixty-five percent of
the lattice. 0 = Flaking and detachment worse than rating 1. Over
sixty-five percent of the lattice is affected. Td = Total
delamination, .sup.3The adhesion between a coating and a windshield
adhesive used in the automotive industry was determined using the
Quick Knife test. Within 1 to 4 hours of the final thirty minute
bake cycle, a bead of the BETASEAL 15625 urethane adhesive
(Supplied by Essex Specialty Products Inc.) was applied to the
surface of the clearcoat of a basecoated and clearcoated panel,
prepared as described above. The plastic nozzle (supplied with
adhesive) was prepared for the urethane # by cutting the tip at
.about.80.degree. angle. The opening measured approximately 5 mm in
diameter. On the long end of the cut edge, a notch approximately 5
mm wide by 2 mm high was cut. The tube of urethane was placed in a
battery powered caulking gun and a small amount was squeezed from
the tube into a paper cup for disposal. The caulking gun was set at
.about.90% speed for a steady flow of adhesive. The plastic tip was
placed on the panel with the notch facing away from the # person
applying the bead. With the tip held firmly on the panel at the
same angle (80.degree.) as the cut nozzle, a steady bead was
applied down the length of the panel. The bead was flat where it
contacted the panel. After the bead was laid, the panel was placed
in a ventilated hood where it remained undisturbed for at least 72
hours @ 20-50% R.H. in order to cure. After the bead cured, the
adhesive bead was cut with a razor blade knife. A small section was
cut at the # beginning of the bead to make it easier to grasp. To
cut the bead, the small beginning section was pulled back at
approximately a 180.degree. angle and slices were made in the
adhesive at a 60.degree. to 80.degree. angle in a quick motion. The
blade was kept in contact with the clearcoat at all times during.
The adhesive bead continued to be pulled while the adhesive was
being cut at .about.1/2" intervals. A minimum of 10 cuts was made.
After making slices to the adhesive bead, # the panel was rated for
% Cohesive Failure (% C.F.) of the bead to the panel. (Cohesive
Failure occurs when the integrity of the adhesive bead is lost as a
result of cutting and pulling rather than the bond between the
adhesive bead and the clearcoat surface.) Failures were reported as
a total % along the bead. For example, if there was 20% of the
urethane remaining on the panel, then it was reported as 20% C.F.
and if the entire bead can be pulled off, it was considered to # be
0% C.F. The desired result was a minimum of 90% or higher
cohesion.
[0237] The data presented above in Table 3 illustrate that recoat
adhesion for the one-package coating compositions of the present
invention improves as the amount of adhesion promoting composition
increases in the composition, while similar comparative
compositions which do not contain the polysiloxane borate have poor
or no recoat adhesion. Further, the data illustrate that while the
comparative composition of Example 7 exhibits very poor (0%) MVSS
cohesive failulre, the compositions of the present invention
(Examples 8 and 9) exhibit excellent (100%) cohesive faillure.
ExampleS 10 Through 13
[0238] The following Examples 10 through 13 presented in Table 4
below describe the preparation of thermosetting coating
compositions based on epoxy containing acrylic resins cured with
acid functional curing agents in combination with aminoplast
resins. The compositions were prepared by admixing the following
ingredients under mild agitation. Note, those comparative
compositions which do not contain a boron-containing compound
(i.e., Comparative Examples 10 and 13) are designated with an
"*".
10TABLE 4 Example Example Example Example 10* 11 12 13* Solids
Solids Solids Solids Resin Resin Resin Resin + Soln. + Soln. +
Soln. + Soln. Materials Additive Wt. Additive Wt. Additive Wt.
Additive Wt. n-pentyl -- 25 -- 25 -- 25 -- 15 propionate.sup.1
DOWANOL .RTM. -- -- -- -- -- -- -- 11.2 DPM.sup.2 TINUVIN
.RTM.-328.sup.3 3 3 3 3 3 3 2.7 2.7 Colloidal silica 10.5 10.5 10.5
-- -- dispersion of Example A 60% GMA resin.sup.4 42.9 67 39.05 61
37.05 58 -- -- 50% GMA resin.sup.5 -- -- -- -- -- -- 56.25 87.9
Primary amyl -- -- -- -- -- -- -- 4.1 alcohol.sup.6 CYMEL 202.sup.7
3 3.8 3 3.8 3 3.8 2.05 2.6 CYLINK .RTM. 2000.sup.8 10 20 10 20 10
20 -- -- Fumed silica -- -- -- -- -- -- 12.9 dispersion.sup.9
Isostearic Acid.sup.10 4 4 4 4 4 4 4.1 4.1 PENTEK.sup.11 34.25 50.4
34.1 50 32.1 47.2 34.2 50.3 Siloxane Borate -- -- 4 8.1 8 16.2 --
-- of Example A TINUVIN .RTM. 123 0.4 0.4 0.4 0.4 0.4 0.4 0.35 0.35
Polybutyl -- -- -- -- -- -- 0.51 0.85 acrylate DISPARLON -- -- --
-- -- -- 0.04 0.08 OX-60.sup.12 Multiflow (50% 0.025 0.05 0.025
0.05 0.025 0.05 0.09 0.18 sol. Of MODAFLOW).sup.13 Di-methyl 0.3
0.3 0.3 0.3 0.3 0.3 0.32 0.32 cocoamine.sup.14 .sup.1Available from
Dow Chemical Co. .sup.2Dipropylene glycol monomethyl ether,
available from Dow Chemical Co.
.sup.32-(2'-Hydroxy-3',5'-dtert-amylphenyl) benzotriazole UV light
stabilizer available from Ciba Specialty Chemicals Corp.
.sup.4Acrylic resin comprising 60% glycidyl methacrylate, 31%
n-butyl methacrylate, 0.2% methyl methacrylate, 7% styrene, 2%
diphenyl-2,4-methyl-4 pentene-1, 66% solids in dipropylene glycol
monomethyl ether and n-amyl propionate. .sup.5Acrylic resin
comprising 50% glycidyl methacrylate, 41% n-butyl methacrylate,
0.2% methyl methacrylate, 7% styrene, 2% diphenyl-2,4-methyl-4
pentene-1, 64% solids in dipropylene glycol monomethyl ether and
n-amyl propionate. .sup.6Available from Dow Chemical Co.
.sup.7Melamine available from Cytec Industries, Inc.
.sup.8Available from Cytec Industries, Inc. .sup.9R-812 silica from
Degussa dispersed in n-amyl alcohol and a trimethylol
propane/methylhexahydrophthalic anhydride half ester of Example G
in U.S. Pat. No. 5,256,452. .sup.10Available from Uniqema.
.sup.11Polyester prepared from 83% 4-methyl hexahydrophthalic
anhydride and 17% pentaerythritol, 67% solids in n-propyl alcohol
and n-amyl propionate. .sup.12Available from Kusumoto, a King
Industries distributor. .sup.13Available from Solutia.
.sup.14Available from Albemarle Corp. The clearcoats prepared as
described above were reduced with DOWANOL .RTM. DPM to a spray
viscosity of 26 seconds at ambient temperature (approximately
76.degree. F. (26.degree. C.)), with a Ford #4 cup.
[0239] Testing
[0240] The film forming compositions of Examples 10-13 were spray
applied to a pigmented basecoat to form color-plus-clear composite
coatings over electrocoated steel panels. The panels used were cold
rolled steel panels (size 4 inches.times.12 inches (10.16 cm by
30.48 cm)). The steel panels for Examples 10-13 were coated with
ED5000 electrocoat, available from PPG Industries, Inc. These
prepared test panels are available as APR23884 from ACT
Laboratories, Inc. of Hillsdale, Mich.
[0241] The basecoat used for Examples 10-13 was HWB-9517, black
pigmented waterborne basecoat, available from PPG Industries, Inc.
The HWB-9517 basecoat was automated spray applied in one coat to
the electrocoated steel panels at ambient temperature (i.e., at
approximately 76.degree. F. (25.degree. C.) and 30% relative
humidity). A dry film thickness of about 0.5 to 0.7 mils (about 13
to 18 micrometers) was targeted. The basecoat was allowed to flash
ambiently for about 5 minutes and then prebaked for five minutes at
200.degree. F. (93.degree. C.).
[0242] The clear coating compositions of Examples 10-13 were each
automated spray applied to a basecoated panel at ambient
temperature in two coats with a 60 second ambient flash between
applications. Coatings of Examples 10-13 were targeted for a 1.8 to
2 mils (about 46 to 51 micrometers) dry film thickness. All
coatings were allowed to air flash at ambient temperature for ten
minutes. Panels prepared from each coating were baked for thirty
minutes at 285.degree. F. (141.degree. C.) to fully cure the
coating(s). The panels were baked in a horizontal position.
[0243] To test for recoat adhesion, an original basecoated and
clearcoated panel, as described above, was given another layer of
basecoat and clearcoat or clearcoat only. Examples 10-13 were
recoated with HWB-9517 basecoat. To recoat the panels half and
half, the right halves of the original panels were covered with
masking tape and then the respective basecoats were automated spray
applied as described above. The tape was removed, resulting in an
original panel with the right half coated in basecoat and the left
half still with only the original coating layers. The respective
clearcoat was then automated spray applied to the entire panel as
described above. The resulting panels were half coated in
basecoat/clearcoat from the original spray application and another
layer of basecoat/clearcoat from the recoat spray application
(B/C//B/C). The other half of the resulting panel was coated in
basecoat/clearcoat from the original spray application and another
layer of clearcoat from the recoat spray application (B/C//C). Test
data is presented below in the following Table 5.
11TABLE 5 Elemental MVSS Recoat Recoat weight % primeless Adhesion
Adhesion Clearcoat on Resin adhesion % pass % pass composition
20.degree. Gloss Solids % pass B/C//B/C B/C//C Example 11 72 0.08
data un- 30 50 available Example 12 72 0.16 88 100 100 Example 10*
83 0 100 0 0 Example 13* 83 0 100 100 100 *Comparative examples
[0244] The data presented in Table 5 above illustrate that the
epoxy-acid clear coat controls of Comparative Examples 10 and 13
pass MVSS primerless adhesion. However, these same the clearcoating
of Example 10 exhibits very poor recoat adhesion when recoated
either with a subsequently applied repair basecoat/clearcoat system
or a repair clearcoat. By contrast, the coating compositions of the
present invention which contain the polysiloxane borate, exhibit
imp-roved recoat adhesion and 100% recoat adhesion (see Examples 11
and 12, respectively).
Two-Component Clearcoating Compositions
Comparative Example 14
[0245] This comparative example describes the preparation of a
two-component clearcoat composition which does not contain an
adhesion promoting compound. The coating composition was prepared
by admixing the following ingredients sequentially under mild
agitation.
12 Parts by Solid weight Ingredient weight (grams) (grams) Methyl
n-amyl ketone 30.0 -- Butyl Cellosolve .RTM. acetate 10.0 -- Butyl
Carbitol .RTM. acetate 5.0 -- Tinuvin 928 3.0 3.0 Tinuvin 292 0.5
0.5 Silica dispersion of Example A 8.8 6.7 Acrylic Resin.sup.1 58.2
42.2 CYMEL .RTM. 202 18.8 15.0 Polysiloxane polyol of Example AA
11.0 11.0 Phenyl Acid Phosphate Catalyst.sup.2 0.7 0.5
DesmodurN3300.sup.4 27.1 27.1 .sup.1Acrylic polyol prepared from
14.5% butyl acrylate, 14.5% butyl methacrylate, 27.6% isobornyl
methacrylate, 22.6% hydroxypropyl methacrylate, 20.4% hydroxyethyl
methacrylate, and 0.4% acrylic acid, having resin solids of 69.7%,
Mw 3227 and a hydroxyl value of 101. .sup.2Phenyl acid phosphate
solution, 75 percent in isopropanol. .sup.3Isocyanurate of
hexamethylene diisocyanate available from Bayer Corp.
Example 15
[0246] This example describes the preparation of a two-component
clearcoat composition of the present invention which contains a
siloxane borate as an adhesion promoting compound. The coating
composition was prepared by admixing the following ingredients
sequentially under mild agitation.
13 Parts by Solid weight Ingredient weight (grams) (grams) Methyl
n-amyl ketone 30.0 -- Butyl Cellosolve .RTM. acetate 10.0 -- Butyl
Carbitol .RTM. acetate 5.0 -- Tinuvin 928 3.0 3.0 Tinuvin 292 0.5
0.5 Silica dispersion of Example A 8.8 6.7 Acrylic Resin of Example
14 58.2 42.2 Cymel 202 18.8 15.0 Polysiloxane polyol of Example AA
10.0 10.0 Siloxane Borate of Example E 2.4 1.0 Phenyl Acid
Phosphate Catalyst 0.7 0.5 DesmodurN3300 27.1 27.1
Example 16
[0247] This example describes the preparation of a two-component
clearcoat composition of the present invention which contains a
siloxane borate as an adhesion promoting compound. The coating
composition was prepared by admixing the following ingredients
sequentially under mild agitation.
14 Parts by Solid Weight Ingredient Weight (grams) (grams) Methyl
n-amyl ketone 30.0 -- Butyl Cellosolve .RTM. acetate 10.0 -- Butyl
Carbitol .RTM. acetate 5.0 -- Tinuvin 928 3.0 3.0 Tinuvin 292 0.5
0.5 Silica dispersion of Example A 8.8 6.7 Acrylic Resin of Example
14 58.2 42.2 Cymel 202 18.8 15.0 Polysiloxane polyol of Example AA
9.0 9.0 Siloxane Borate of Example E 4.9 2.0 Phenyl Acid Phosphate
Catalyst 0.7 0.5 DesmodurN3300 27.1 27.1
Example 17
[0248] This example describes the preparation of a two-component
clearcoat composition of the present invention which contains a
siloxane borate as an adhesion promoting compound. The coating
composition was prepared by admixing the following ingredients
sequentially under mild agitation.
15 Parts by Solid Weight Ingredient Weight (grams) (grams) Methyl
n-amyl ketone 30.0 -- Butyl Cellosolve .RTM. acetate 10.0 -- Butyl
Carbitol .RTM. acetate 5.0 -- Tinuvin 928 3.0 3.0 Tinuvin 292 0.5
0.5 Silica dispersion of Example A 8.8 6.7 Acrylic Resin of Example
14 58.2 42.2 Cymel 202 18.8 15.0 Polysiloxane polyol of Example AA
7.0 7.0 Siloxane Borate of Example E 9.8 4.0 Phenyl Acid Phosphate
Catalyst 0.7 0.5 DesmodurN3300 27.1 27.1
Example 18
[0249] This example describes the preparation of a two-component
clearcoat composition of the present invention which contains a
boric acid as an adhesion promoting compound. The coating
composition was prepared by admixing the following ingredients
sequentially under mild agitation.
16 Parts by Solid Weight Ingredient Weight (grams) (grams) Methyl
n-amyl ketone 30.0 -- Butyl Cellosolve .RTM. acetate 10.0 -- Butyl
Carbitol .RTM. acetate 5.0 -- Tinuvin 928 3.0 3.0 Tinuvin 292 0.5
0.5 Silica dispersion of Example A 8.8 6.7 Acrylic Resin of Example
14 58.2 42.2 Cymel 202 18.8 15.0 Polysiloxane polyol of Example AA
11.0 11.0 Boric acid (20% solution in 1.3 0.3 methanol) Phenyl Acid
Phosphate Catalyst 0.7 0.5 DesmodurN3300 27.1 27.1
Example 19
[0250] This example describes the preparation of a two-component
clearcoat composition of the present invention which contains a
boric acid as an adhesion promoting compound. The coating
composition was prepared by admixing the following ingredients
sequentially under mild agitation.
17 Parts by Solid Weight Ingredient Weight (grams) (grams) Methyl
n-amyl ketone 30.0 -- Butyl Cellosolve .RTM. acetate 10.0 -- Butyl
Carbitol .RTM. acetate 5.0 -- Tinuvin 928 3.0 3.0 Tinuvin 292 0.5
0.5 Silica dispersion of Example A 8.8 6.7 Acrylic Resin of Example
14 58.2 42.2 Cymel 202 18.8 15.0 Polysiloxane polyol of Example AA
11.0 11.0 Boric acid (20% solution in 5.0 1.0 methanol) Phenyl Acid
Phosphate Catalyst 0.7 0.5 DesmodurN3300 27.1 27.1
Example 20
[0251] This example describes the preparation of a two-component
clearcoat composition of the present invention which contains
triisopropyl borate as an adhesion promoting compound. The coating
composition was prepared by admixing the following ingredients
sequentially under mild agitation.
18 Parts by Solid Weight Ingredient Weight (grams) (grams) Methyl
n-amyl ketone 30.0 -- Butyl Cellosolve .RTM. acetate 10.0 -- Butyl
Carbitol .RTM. acetate 5.0 -- Tinuvin 928 3.0 3.0 Tinuvin 292 0.5
0.5 Silica dispersion of Example A 8.8 6.7 Acrylic Resin of Example
14 58.2 42.2 Cymel 202 18.8 15.0 Polysiloxane polyol of Example AA
11.0 11.0 Triisopropyl Borate.sup.1 0.9 0.9 Phenyl Acid Phosphate
Catalyst 0.7 0.5 DesmodurN3300 27.1 27.1 .sup.1Available from
Aldrich Chemical Co.
Example 21
[0252] This example describes the preparation of a two-component
clearcoat composition of the present invention which contains
borate ester as an adhesion promoting compound. The coating
composition was prepared by admixing the following ingredients
sequentially under mild agitation.
19 Parts by Solid Weight Ingredient Weight (grams) (grams) Methyl
n-amyl ketone 30.0 -- Butyl Cellosolve .RTM. acetate 10.0 -- Butyl
Carbitol .RTM. acetate 5.0 -- Tinuvin 928 3.0 3.0 Tinuvin 292 0.5
0.5 Silica dispersion of Example A 8.8 6.7 Acrylic Resin of Example
14 58.2 42.2 Cymel 202 18.8 15.0 Polysiloxane polyol of Example AA
11.0 11.0 Bonc Acid Ester of Example F 2.2 0.3 Phenyl Acid
Phosphate Catalyst 0.7 0.5 DesmodurN3300 27.1 27.1
Example 22
[0253] This example describes the preparation of a two-component
clearcoat composition of the present invention which contains an
acrylic borate as an adhesion promoting compound. The coating
composition was prepared by admixing the following ingredients
sequentially under mild agitation.
20 Parts by Solid Weight Ingredient Weight (grams) (grams) Methyl
n-amyl ketone 30.0 -- Butyl Cellosolve .RTM. acetate 10.0 -- Butyl
Carbitol .RTM. acetate 5.0 -- Tinuvin 928 3.0 3.0 Tinuvin 292 0.5
0.5 Silica dispersion of Example A 8.8 6.7 Boric Acid Ester of
Example G 60.9 42.2 Cymel 202 18.8 15.0 Polysiloxane polyol of
Example AA 11.0 11.0 Phenyl Acid Phosphate Catalyst 0.7 0.5
DesmodurN3300 27.1 27.1
Example 23
[0254] This example describes the preparation of a two-component
clearcoat composition of the present invention which contains a
siloxane aluminum isopropoxide as an adhesion promoting compound.
The coating composition was prepared by admixing the following
ingredients sequentially under mild agitation.
21 Parts by Solid Weight Ingredient Weight (grams) (grams) Methyl
n-amyl ketone 30.0 -- Butyl Cellosolve .RTM. acetate 10.0 -- Butyl
Carbitol .RTM. acetate 5.0 -- Tinuvin 928 3.0 3.0 Tinuvin 292 0.5
0.5 Silica dispersion of Example A 8.8 6.7 Acrylic Resin of Example
14 58.2 42.2 Cymel 202 18.8 15.0 Polysiloxane polyol of Example AA
Siloxane Aluminum isopropoxide of 42.9 22.9 Example H Phenyl Acid
Phosphate Catalyst 0.7 0.5 DesmodurN3300 27.1 27.1
[0255] The clearcoats Examples 14 through 23 described above were
reduced in viscosity to about 25 seconds on a #4 Ford efflux cup at
ambient temperature using methyl n-amyl ketone.
[0256] Testing
[0257] The film forming compositions of Examples 14-23 were spray
applied to a pigmented basecoat to form color-plus-clear composite
coatings over primed electrocoated steel panels. The panels used
were cold rolled steel panels (size 4 inches.times.12 inches (10.16
cm by 30.48 cm)). The steel panels for Examples 14-23 were coated
with ED5050B electrocoat, available from PPG Industries, Inc, and
1177225A primer surfacer, also available from PPG Industries, Inc
or coated with ED5000 electrocoat, available from PPG Industries,
Inc, and GPXH5379 primer surfacer, also available from PPG
Industries, Inc. The test panels are available as APR39754 or
APR39375 from ACT Laboratories, Inc. of Hillsdale, Mich.
[0258] The basecoat used for Examples 14-23 was Obsidian Schwarz,
black pigmented waterborne basecoat; available from BASF
Corporation. The Obsidian Schwarz basecoat was automated spray
applied in two coats with approximately 30 second flash between
coats to the electrocoated and primed steel panels at about
70.degree. F. (21.degree. C.) temperature and about 60% relative
humidity. A dry film thickness of about 0.5 to 0.6 mils (about 12
to 16 micrometers) was targeted. The basecoat was allowed to flash
ambiently for about five minutes and then prebaked for five minutes
at 176.degree. F. (80.degree. C.).
[0259] The clear coating compositions of Examples 14-23 were each
automated spray applied to a basecoated panel at ambient
temperature in two coats with about a 30 second ambient flash
between coats. Examples 1-10 were targeted for a 1.5 to 2.0 mils
(about 38 to 51 micrometers) dry film thickness. All coatings were
allowed to air flash at ambient temperature for ten minutes. Panels
prepared from each coating were baked for 30 minutes at 285.degree.
F. (141.degree. C.) to fully cure the coating(s). The panels were
baked in a horizontal position.
[0260] To test for recoat adhesion, an original basecoated and
clearcoated panel, as described above, was given another layer of
basecoat and clearcoat or clearcoat only. With the condition of
sanding, the right half of the panel was sanded with 1200 grit sand
paper and the left half was not sanded thus giving sanded and
non-sanded areas. Half of an original panel from each clear coating
was basecoated and clearcoated and the other half of the panel was
clearcoated only. To recoat the panels half and half, the bottom
halves of the original panels were covered with aluminum foil and
then the top halves were recoated with Obsidian Schwarz basecoat
using the same conditions as above. The foil was removed, resulting
in an original panel with the upper half coated in basecoat and the
bottom half still with only the original coating layers. The
respective clearcoat was then automated spray applied to the entire
panel as described above. The resulting panels were half coated in
basecoat/clearcoat from the original spray application and another
layer of basecoat/clearcoat from the recoat spray application
(B/C//B/C). The other half of the resulting panel was coated in
basecoat/clearcoat from the original spray application and another
layer of clearcoat from the recoat spray application (B/C//C). Test
data is reported below in the following Table 6.
22 TABLE 6 Adhesion Recoat Adhesion-Cross Hatch promoter
30/285.degree. F. (141.degree. C.)// Elemental 30/285.degree. F.
(141.degree. C.) Weight % Sanded +HC,25/ Non-Sanded on Resin B/C//
B/C// B/C// B/C// Example # Solids 20.degree. Gloss B/C C B/C C 14*
0 84 5 5 0 0 15 0.02 84 5 5 5 0 16 0.04 85 5 5 5 0 17 0.08 84 5 5 5
5- 18 0.04 84 5 5 5 0 19 0.16 85 5 5 5 5- 20 0.04 85 -- -- 5 0 21
0.04 85 -- -- 5 0 22 0.03 85 -- -- 5 0 23 0.10 82 5 5 5 0
*Designates a comparative example.
[0261] The data presented above in Table 6 illustrate that the
inclusion in a two-component clearcoating composition of the
adhesion promoting composition of Examples C through H above
provide excellent adhesion where a basecoat/clearcoat system is
recoated with a repair basecoat/clearcoat system. Further, the data
for Examples 14-22 illustrate that the inclusion of the
polysiloxane borate and boric acid (where the composition also
comprises a polysiloxane) at levels of elemental boron of 0.08 or
greater, show excellent adhesion where a basecoat/clearcoat system
is repaired with a clearcoat.
[0262] Basecoating Compositions
[0263] Examples 24 and 25 describe the preparation of basecoating
compositions. Comparative Example 24 describes the preparation of
an aqueous basecoating composition which does not contain the
polysiloxane borate as an adhesion promoter. Example 25 describes
the preparation of a pigment-containing basecoating composition
according to the present invention which contains a polysiloxane
borate as an adhesion promoter.
Comparative Example 24
[0264] An aqueous silver metallic basecoat composition was prepared
in three stages as follows. The first four components of the
"organic portion" of the basecoat were combined and then agitated
until well dispersed. The next two ingredients were then added
under agitation and mixed for 20 minutes, followed by addition of
the last ingredient which was added under agitation until
dispersed.
[0265] In a separate container, the "thickener portion" of the
basecoat was prepared by combining the three ingredients under
agitation and mixed for 20 minutes.
[0266] The "aqueous portion" of the basecoat was assembled by
adding each aqueous component under agitation and mixing for
approximately 10 minutes until well blended. The organic portion
was then added slowly to the aqueous portion and agitated for 20
minutes. The pH of the admixture was adjusted to 8.5-8.7 with a 50%
solution of dimethylethanol amine and deionized water. The
thickener portion was then added and again the pH was adjusted. The
resulting basecoating composition was allowed to equilibrate for 24
hours before the final pH adjustment was made. At that time, the
basecoating composition was reduced in viscosity to 25-27 seconds
using a 4 Ford Cup with deionized water before spraying.
23 Resin Pigment Additive Solution Solids Solids Solids Weight
(grams) (grams) (grams) (grams) Organic Portion N-Butoxypropanol 0
0 0 45.04 Cymel 303LF.sup.1 25 0 0 25 Cymel 385.sup.2 5 0 0 6.25
TINUVIN .RTM. 1130.sup.3 0 0 1.4 1.40 Aqua Paste 3620-D23.sup.4 1.5
15.1 0 23.50 Aqua Paste 3700-A23.sup.5 0.4 4.3 0 6.50 Phosphatized
Epoxy.sup.6 0 0 0.24 0.39 Aqueous Portion SHELLSOL .RTM. 071.sup.7
0 0 0 6 Latex resin.sup.8 58.1 0 0 140 Deionized water 0 0 0 50
Acrylic Grind 6 0 0 23.1 Dispersion.sup.9 50% dimethanolamine 0 0 0
2.2 solution Thickener Solution Deionized water 0 0 0 10 50% DMEA
Solution 0.0 0.0 0.0 2.5 Oligomeric Polyester.sup.10 4 0.0 0.0 5
.sup.1Melamine available from Cytec Industries, Inc. .sup.2Melamine
available from Cytec Industries, Inc. .sup.3Substituted
benzotriazole UV light absorber available from Ciba Additives.
.sup.4Aqua Paste, treated aluminum available from Silberline
Manufacturing Co., Inc. .sup.5Aqua Paste, treated aluminum
available from Silberline Manufacturing Co., Inc.
.sup.6Phosphatized epoxy prepared from EPON .RTM.828, a
polyglycidyl ether of Bisphenol A, available form Shell Oil and
Chemical Co.; reacted with phosphoric acid at an 83:17 weight
ratio. .sup.7Mineral spirits available from Shell Chemical Co.
.sup.8Latex prepared as follows: (I) a polyester resin was prepared
by adding to a four-neck round bottom flask equipped with a
thermometer, mechanical stirrer, condenser, dry nitrogen sparge,
and a heating mantle, the following ingredients: 1103.0 g
isostearic acid, 800.0 g pentaerythritol, 470.0 g crotonic acid,
688.0 g phthalic anhydride, 6.1 g dibutyltin oxide, 6.1 g triphenyl
phosphite, # 1170.0 g butyl acrylate, and 4.0 g Ionol (butylated
hydroxytoluene). The first six ingredients were stirred in the
flask at 210.degree. C. until 245 ml of distillate was collected
and the acid value dropped to 4.6. The material was cooled to
77.degree. C. and the last two ingredients were stirred in. The
final product was a viscous yellow liquid with a hydroxyl value of
54.0, a Gardner-Holdt viscosity # of Z+, a weight average molecular
weight of 45,600, and a non-volatile content of 70.2%; (II) a
pre-emulsion was prepared by stirring together the following
ingredients: 286.0 g of the polyester of (I), 664.0 g butyl
acrylate, 30.0 g ethylene glycol dimethacrylate, 20.0 g acrylic
acid, 46.4 g dodecylbenzenesulfonic acid (70% in isopropanol), 14.3
g dimethylethanolamine, and 1000.0 g water. The # pre-emulsion was
passed once through a Microfluidizer .COPYRGT. M110T at 8000 psi
and transferred to a fourneck round bottom flask equipped with an
overhead stirrer, condenser, thermometer, and a nitrogen
atmosphere. 150.0 g of water used to rinse the Microfluidizer .RTM.
was added to the flask. The polymerization was initiated by adding
3.0 g of isoascorbic acid and 0.02 g of ferrous ammonium # sulfate
dissolved in 120.0 g water followed by a thirty minute addition of
4.0 g of 70% t-butyl hydroperoxide dissolved in 115.0 g of water.
The reaction exothermed from 23.degree. C. to 80.degree. C. After
the temperature was reduced to 30.degree. C., 36 g of 33.3% aqueous
dimethylethanolamine was added followed by 2.0 g of Proxel GXL
(Biocide available from ICI Americas, Inc.) # in 8.0 g of water.
The final pH of the latex was 8.0, the nonvolatile content was
42.0%, the particle size was 105 nm, and the Brookfield viscosity
was 12 cps (spindle #1, 50 rpm). .sup.9Acrylic dispersion grind
vehicle (35% butyl acrylate, 30% styrene, 18% butyl methacrylate,
8.5% hydroxyethyl acrylate, and 8.5% acrylic acid). .sup.10Prepared
according to U.S. Pat. No. 5,356,973, Example A.
Example 25
[0267] This example describes a pigment-containing basecoating
composition of the present invention which contains a polysiloxane
borate as an adhesion promoter. The basecoating composition was
prepared in three stages as described above with reference to the
basecoating composition of Comparative Example 24.
24 Resin Pigment Additive Solution Solids Solids Solids Weight
(grams) (grams) (grams) (grams) Organic Portion N-Butoxypropanol 0
0 0 45.04 Cymel 303LF 25 0 0 25 Cymel 385 5 0 0 6.25 TINUVlN .RTM.
1130 0 0 1.4 1.40 Aqua Paste 3620-D23 1.5 15.1 0 23.50 Aqua Paste
3700-A23 0.4 4.3 0 6.50 Phosphatized Epoxy 0 0 0.24 0.39 Aqueous
Portion SHELLSOL .RTM. 071 0 0 0 6 Latex of Example 24 58.1 0 0 140
Deionized water 0 0 0 50 Acrylic Grind 6 0 0 23.1 Dispersion of
Example 24 50% DMEA solution 0 0 0 2.2 Thickener Solution Deionized
water 0 0 0 10 50% DMEA Solution 0.0 0.0 0.0 2.5 Oligomeric
Polyester 4 0.0 0.0 5 of Example 24 Adhesion promoter Polysiloxane
borate of 0 0 .5 .9 Example I
[0268] The polysiloxane borate of Example I was post-added under
agitation to the basecoating composition of Example 25 in the
amounts indicated above.
[0269] Testing
[0270] Each of the basecoating compositions of Comparative Example
24 and Example 25 was applied on ED5000 panels primed with GPXH5379
using the Sames 402 gun mounted on the Kohne machine in a one-coat
application. The basecoats were given a five minute ambient flash
and then pre-baked at the various conditions listed in the
following Table 7. Basecoat film build was targeted at 0.5 to 0.7
mils. A two-component isocyanate-containing clearcoat, TKU-1050AR
(available from PPG Industries, Inc.) was applied under the same
conditions as was the basecoat, except the clearcoating composition
was applied in two coats. The panels thus prepared were given a ten
minute ambient flash period before curing for 30 minutes at
250.degree. F. (121.degree. C.). The cured clearcoat dry film
thickness ranged from 1.8-2.0 mils (45.7 to 50 micrometers).
[0271] Note, a 5 minute at 200.degree. F. (93.degree. C.) prebake
is the standard prebake condition. The 10 minute prebake at
250.degree. F. (121.degree. C.) prebake which was used in the above
described evaluations was intended to simulate an over pre-bake
condition (as would be encountered on a commercial coating line
should there be a malfunction in the prebake oven).
[0272] A 30 minute prebake at 250.degree. F. (121.degree. C.)/5
minute prebake at 200.degree. F. (93.degree. C.) was used to
simulate a malfunction in the clearcoat booth or oven. In this
instance, the basecoat is applied and given a standard prebake but
no clearcoat is applied due to a malfunction on the clearcoating
line. Thus the basecoat receives a full clearcoat bake of 30
minutes at 250.degree. F. (121.degree. C.). As mentioned above, in
such situations, some automobile manufacturers elect to reapply the
basecoat and give it a standard prebake before clearcoating.
[0273] Adhesion was tested 1 hour after clearcoating using a razor
knife to cut a 6.times.6 two-millimeter grid through the total
paint coating and then taping with black Tesa tape. The adhesion is
rated according to ASTM D 3359-97 which assigns a whole number from
5(no adhesion loss) to 0(total adhesion loss). In this case an
acceptable adhesion rating is a 5 or a 4. For the 10 minutes at
250.degree. F. prebake scenario described above, the adhesion
between clearcoat and basecoat was evaluated. For the 30 minutes at
250.degree. F. (121.degree. C.)/5 minutes at 250.degree. F.
(121.degree. C.) prebake scenario described above, the adhesion
between the basecoat layers was evaluated. Adhesion test results
are presented below in the following Table 7.
25TABLE 7 CROSS Elemental HATCH BASECOATING Weight % on PREBAKE
ADHESION COMPOSITION Resin Solids SCENARIO RATING EXAMPLE 24* 0 5'
at 200 F. (standard) 5 EXAMPLE 25 0.01 5' at 200 F. (standard) 5
EXAMPLE 24* 0 10' at 250 F. 0 EXAMPLE 25 0.01 10' at 250 F. 5
EXAMPLE 24* 0 30' at 250 F./5' at 0 200 F. EXAMPLE 25 0.01 30' at
250F./5' at 5 200 F.
[0274] The data presented above in Table 7 illustrates that the
basecoating composition of Comparative Example 24 does not exhibit
acceptable clearcoat-to-basecoat adhesion when the basecoat
undergoes an extended prebake (10' at 250.degree. F. (121.degree.
C.) prebake). Nor does this basecoat exhibit acceptable
basecoat-to-basecoat adhesion when the basecoat is fully baked and
then another layer of basecoat is applied and given the standard
prebake (30' at 250.degree. F. (121.degree. C.)/5' at 200.degree.
F. (93.degree. C.) prebake) before clearcoating. By contrast, the
basecoating compositions of the present invention comprising the
polysiloxane borate as an adhesion promoter exhibits excellent
adhesion in both prebake scenarios.
Carbamate-Containing Clearcoat Compositions
Comparative Example 26
[0275] This comparative example describes the preparation of
thermosetting clearcoating composition which does not contain an
adhesion promoter. The clearcoating composition was prepared by
mixing together the following ingredients sequentially:
26 Ingredient Solid Weight (g) Solution Weight. (g) Xylene 5.75
Aromatic 100 12.00 Hexyl cellosolve 2.57 Methyl Ethyl Ketone 11.7
Tinuvin 328.sup.1 1.29 1.29 Tinuvin 900.sup.2 1.29 1.29 Acrylic
Microgel 1.74 5.79 Dispersion.sup.3 Silica Dispersion.sup.4 9.17
21.3 RESIMENE 757.sup.5 38.13 39.3 Ethanol 4.45 Carbamate
functional 39.5 54.9 Polyester of Example CC Carbamate Functional
13.17 20.9 Acrylic of Example BB Tinuvin 292.sup.6 0.32 0.32
DISPARLON OX-60.sup.7 0.06 0.12 Flow Additive.sup.8 0.38 0.63
Catalyst.sup.9 1.03 1.47 .sup.1Substituted benzotriazole UV Light
stabilizer available from Ciba Geigy Corporation. .sup.2Substituted
benzotriazole UV Light stabilizer available from Ciba Geigy
Corporation. .sup.3A non-aqueous dispersion of an acrylic polymer
formed from ethyleneglycol dimethacrylate, styrene, butyl acrylate
and methyl methacrylate. .sup.4Fumed silica grind. .sup.5A fully
alkylated methoxy/butoxy functional aminoplast available from
Solutia, Inc. .sup.6Sterically hindered amine light stabilizer
available from Ciba Geigy Corporation. .sup.7Additive from King
Industries. .sup.8Additive from DuPont. .sup.9Dodecyl benzene
sulfonic acid solution.
Example 27
[0276] This example describes the preparation of a clearcoating
composition of the present invention which contains a boric acid
ester as an adhesion promoter. The clearcoatng composition was
prepared by mixing together the following ingredients:
27 Ingredients Solid Weight. (g) Solution Weight. (g) Clearcoating
106.08 184.9 Composition of Example 26 Boric Acid Ester 1.0 1.4 of
Example J
Example 28
[0277] This example describes the preparation of a clearcoating
composition of the present invention which contains a boric acid
ester as an adhesion promoter. The clearcoating composition was
prepared by mixing together the following ingredients:
28 Ingredients Solid Weight. (g) Solution Weight. (g) Clearcoating
106.08 184.9 Composition of Example 26 Polysiloxane polyol 1.0 1.0
of Example AA Boric Acid Ester of 0.56 0.90 Example F
Example 29
[0278] This example describes the preparation of a clearcoating
composition of the present invention which contains a boric acid
ester as an adhesion promoter. The clearcoating composition was
prepared by mixing together the following ingredients:
29 Ingredients Solid Weight. (g) Solution Weight. (g) Clearcoating
106.08 184.5 composition of Example 26 Boric Acid Ester 0.56 0.90
of Example F
Comparative Example 30
[0279] This comparative example describes the preparation of a
clearcoating which contains a polysiloxane polyol, but no adhesion
promoter. The clearcoating composition was prepared by mixing
together the following ingredients:
30 Ingredients Solid Weight (g) Solution Weight (g) Clearcoating
106.08 184.5 composition of Example 26 Polysiloxane polyol 0.88
0.88 of Example AA
[0280] Testing
[0281] The film-forming compositions of Examples 26-30 were applied
to pigmented basecoats to form color-plus-clear composite coatings
over a steel substrate previously coated with an electrocoat primer
and a primer surfacer. The basecoat used for the examples is
commercially available from PPG Industries, Inc. and is identified
as ODCT6505 (silver metallic). The primer used is commercially
available from PPG Industries, Inc. and is identified as FCP-6759.
The electrocoat used on the steel is commercially available from
PPG Industries, Inc. and is identified as ED5000.
[0282] The basecoat was spray applied in two coats to the primed
electrocoated steel panels at a temperature of about 75.degree. F.
(24.degree. C.). A 60 seconds flash time was allowed between the
two basecoat applications. After the second basecoat application, a
90 seconds flash time was allowed at about 75.degree. F.
(24.degree. C.) before the application of the clear coating
composition. The clear coating compositions of Examples 26-30 were
each applied to a basecoated panel in two coats with a 60 seconds
flash at 75.degree. F. (24.degree. C.) allowed between coats. The
composite coating was allowed to air flash at about 75.degree. F.
(24.degree. C.) for 8-10 minutes before baking at 285.degree. F.
(141.degree. C.) to cure both the basecoat and the clearcoat. The
panels were baked in a horizontal position. The colored panel for
each clearcoat example was baked for 30 minutes and used to test
for adhesion.
[0283] In order to test the adhesion of the clearcoat to the
windshield adhesive, a bead of windshield adhesive was applied to
the clearcoat surface within 1-4 hours following the 30 minutes at
285.degree. F. (141.degree. C.) bake. The windshield adhesive used
for Examples 26-30 is commercially available from Essex Speciality
Products Company and is identified as Adhesive 15625.
[0284] A 5 mm x 5 mm x 250 mm adhesive bead was placed on the
clearcoat surface of the cured color-plus-clear composite. The
adhesive plus the color-plus-clear composite was cured for 72 hours
at about 75.degree. F. (24.degree. C.) and 20-50% relative
humidity. The cured adhesive bead was cut with a razor blade. A cut
was made through the adhesive bead at a 600 angle at 12 mm
intervals while pulling back the edge of the adhesive at a 1800
angle. A minimum of 10 cuts was done for each system. The desired
result is described as 100% cohesive failure (CF). Cohesive failure
(CF) occurs when the integrity of the adhesive bead is lost as a
result of cutting and pulling rather than the bond between the
adhesive bead and the clearcoat surface. The adhesion results over
the silver metallic basecoat are summarized in Table 8 below.
31 TABLE 8 Percent CLEARCOATING Cohesive Failure COMPOSITION (% CF)
Example 26* 0% CF Example 27 100% CF Example 28 100% CF Example 29*
0% CF Example 30* 0% CF *Comparative Examples
[0285] The data presented above in Table 8 illustrate that in the
absence of the siloxane plus borate combination (Comparative
Examples 26, 29 and 30) the adhesive beads do not adhere to the
clearcoat surface indicating 0% cohesive failure. By contrast,
clearcoats containing a siloxane plus borate additive (Examples 27
and 28) adhere strongly to the adhesive beads (100% cohesive
failure) and the mode of failure occurs within the adhesive bead
itself.
Powder Coating Compositions
ExampleS 31 Through 33
[0286] Each epoxy-acid powder clearcoat composition in Examples 31
through 33 in Table 9 below is shown in parts by weight. Each
composition was processed in the following manner. The components
were blended in a Henschel Mixer for 60 to 90 seconds. The mixtures
were then extruded through a Werner & Pfleider co-rotating twin
screw extruder operating at a screw speed of 450 RPM with barrel
temperatures adjusted to produce extrudate at a temperature of
100.degree. C. to 125.degree. C. The extruded material was then
ground to a mean particle size of 17 to 27 microns using an ACM 2
(Air Classifying Mill from Hosakowa Micron Powder Systems). The
finished powders were electrostatically sprayed onto test panels
and evaluated for coatings properties.
32TABLE 9 Example 31 Component Comparative Example 32 Example 33
.sup.1GMA Acrylic 69.99 69.80 67.57 Dodecanedioic Acid 20.91 20.85
20.18 .sup.2Flow Additive 1.00 1.00 0.97 Benzoin 0.20 0.20 0.19
.sup.3Wax C Micropowder 0.60 0.60 0.58 .sup.4Tinuvin 144 2.00 2.00
1.94 .sup.5CGL 1545 2.00 2.00 1.94 .sup.6HCA-1 2.00 2.00 1.94
.sup.7Armeen M2C 1.00 1.00 0.97 .sup.8Aluminum Oxide 0.30 0.30 0.29
.sup.9Orthoboric Acid 0.00 0.25 0.00 Siloxane Borate 0.00 0.00 3.55
of Example I .sup.1Proprietary Acrylic .sup.2Proprietary Flow
Additive .sup.3Wax C Micropowder, a fatty acid amide (ethylene
bis-stearolyamide), commercially available from Hoechst-Celanese.
.sup.42-tert-butyl-2-(4-hydroxy-3,5-di-tert-butylbenzyl)[bis(methyl-2,2,6-
,6,-tetramethyl-4-piperidinyl)]dipropionate), an ultraviolet light
stabilizer commercially available from Ciba-Geigy Corp.
.sup.52-[4((2-Hydroxy-3-(2-ethylhexyloxy)propyl)-oxy]-2-hydroxyphenyl)-4,-
6-bis(2,4-dimethylphenyl)-1,3,5-triazine), an ultraviolet light
stabilizer commercially available form Ciba-Geigy Corp.
.sup.6HCA-1, an anti-yellowing agent commercially available from
Sanko Chemical Corp. .sup.7Methyl dicocoamine commercially
available from Akzo-Nobel Corp. .sup.8Microgrit WCA3 commercially
available from Micro Abrasives. .sup.9Optibor TP, commercially
available from U.S. Borax, Inc.
[0287] Each of the powder coating compositions of Examples 31 to 33
was prepared for testing in the following manner. The test panels,
pre-coated with an electrocoat primer commercially available from
PPG Industries, Inc., as ED5000 were coated with a primer/surfacer
and a basecoat by spray application to a film thickness of 1.1 mils
(27.9 microns) and 0.6 mils (15.2 microns) respectively, with gray
solventborne primer commercially available form Akzo-Nobel Corp.,
and a waterborne silver basecoat (prepared by blending under
agitation: 171.6 g SHELLSOL.RTM.071, 1700.4 g resin (dispersion
prepared from 60% acrylic grafted to 40% poylurethane), 902.2 g
DOATAN 6462 available from Solutia, 559 g Hexyl Cellosolve.RTM.),
31.2 g dimethylethanolamine 50%solution, 2876.9 g deionized water,
102.7 g octanol, 37.7 g Tinuvin.RTM.1130, 13 g phosphatized epoxy
(prepared from EPON.RTM.828, a polyglicydyl ether of Bisphenol A,
available form Shell Oil and Chemical Co., reacted with phosphoric
acid at an 83:17 weight ratio.), 260 g Cymel.RTM.303LF melamine
available from Cytec Industries, Inc., 365.3 g TOYO 7106 NS
untreated aluminum available from Toyo Aluminum K. K. and 107.9 g
aluminum passivator prepared according to U.S. Pat. No. 5,429,674
Example 6.). The basecoat panels were then flashed 10 minutes at
176.degree. F. (80.degree. C.) before electrostatically applying
the powder clearcoating compositions of Examples 31 to 33. The
powder coatings were applied at 1.97-2.36 mils (50-60 microns) film
thickness and cured for 30 minutes at 293.degree. F. (145.degree.
C.). Test panels were then given a second layer of the waterborne
silver basecoat. Finally, a two component isocyanate clearcoat
commercially available from BASF, was applied at a film thickness
of 1.6 to 1.8 mils (40.6 to 45.7 microns) and cured for 20 minutes
at 293.degree. F. (145.degree. C.). The test panels coated with the
powder clearcoats from Examples 31 to 33 were then evaluated for
adhesion by the following procedure:
[0288] A cutting template, Super Cutter Guide manufactured by Taiyu
Kizai Co Ltd, was used along with a blade to scribe a grid into the
test panels. The lines of the grid are spaced 3 mm apart. Black
tape available as Tesa 4651 through Beiersdorf .DELTA.G is then
placed across the grid and rubbed to insure good surface contact.
The tape is then yanked off. The panels are then rated according to
the percentage of surface area of the grid that was pulled off the
grid as % failure.
[0289] Results are reported in Table 10 below.
33 TABLE 10 Coating Composition % Failure Comparative Example 31
100% complete delamination Example 32 35% partial delamination
Example 33 8% slight delamination
[0290] The data presented above in Table 10 illustrate that the
powder clearcoating compositions of the present invention (Examples
32 and 33) provide improved adhesion over that of the Comparative
Example 31 which contains no boron-containing compound.
[0291] It will be appreciated by those skilled in the art that
changes could be made to the embodiments described above without
departing from the broad inventive concept thereof. It is
understood, therefore, that this invention is not limited to the
particular embodiments disclosed, but it is intended to cover
modifications which are within the spirit and scope of the
invention, as defined by the appended claims.
* * * * *