U.S. patent number RE34,730 [Application Number 08/043,968] was granted by the patent office on 1994-09-13 for polyurethane resins in water-dilutable basecoats having low flash and quick-drying characteristics.
This patent grant is currently assigned to BASF Corporation, Inmont Division. Invention is credited to Robert A. Aamodt, Thomas C. Balch, Michael C. Knight, Paul E. Lamberty, Timothy Salatin, Michael D. Shesterkin, John S. Van Antwerp.
United States Patent |
RE34,730 |
Salatin , et al. |
September 13, 1994 |
Polyurethane resins in water-dilutable basecoats having low flash
and quick-drying characteristics
Abstract
This invention, therefore, relates to the field of polyurethane
coatings for use in automobile basecoat/clearcoat systems. In
particular, this invention relates to the discovery that
incorporating a long-chain carboxylic acid of at least 50% by
weight of the carboxylic acid component used to make polyester
resins which are further incorporated into polyurethane resins
provides basecoat composition exhibiting low temperature flash
characteristics. These low temperature flash characteristics are
exhibited even where the basecoat is deposited at 50-90% relative
humidity.
Inventors: |
Salatin; Timothy (Farmington
Hills, MI), Balch; Thomas C. (West Bloomfield, MI),
Knight; Michael C. (Center Line, MI), Shesterkin; Michael
D. (Farmington Hills, MI), Van Antwerp; John S. (St.
Sauveur, CA), Lamberty; Paul E. (Romeo, MI),
Aamodt; Robert A. (Grand Prairie, TX) |
Assignee: |
BASF Corporation, Inmont
Division (Clifton, NJ)
|
Family
ID: |
26715141 |
Appl.
No.: |
08/043,968 |
Filed: |
April 8, 1993 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
379244 |
Jul 12, 1989 |
|
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|
Reissue of: |
38385 |
Apr 15, 1987 |
04791168 |
Dec 13, 1988 |
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Current U.S.
Class: |
427/407.1;
427/409; 427/412.1; 427/412.3; 427/429; 428/357; 428/423.1;
428/458; 524/601; 524/602; 525/440.08; 525/441; 525/444.5; 528/288;
528/295.3; 528/296; 528/302 |
Current CPC
Class: |
B05D
5/068 (20130101); B05D 7/53 (20130101); C08G
18/0823 (20130101); C08G 18/4233 (20130101); C08G
18/6659 (20130101); C09D 175/06 (20130101); C09D
175/06 (20130101); C09D 175/06 (20130101); C08L
2666/16 (20130101); C08L 2666/18 (20130101); Y10T
428/31551 (20150401); Y10T 428/31681 (20150401); Y10T
428/29 (20150115) |
Current International
Class: |
B05D
7/00 (20060101); B05D 5/06 (20060101); C08G
18/08 (20060101); C08G 18/00 (20060101); C08G
18/66 (20060101); C08G 18/42 (20060101); C09D
175/06 (20060101); B05D 001/36 () |
Field of
Search: |
;524/601,602
;525/440,441,444.5 ;528/288,295.3,296,302 ;428/458,357,423.1
;427/407.1,409,412.1,412.3,426 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Acquah; Samuel A.
Attorney, Agent or Firm: Kenyon & Kenyon
Parent Case Text
.Iadd.This application is a continuation of Reissue application
Ser. No. 07/379,244 filed Jul. 12, 1989 which is derived from U.S.
Pat. No. 4,791,168, issued Dec. 13, 1989.
Claims
.[.1. A basecoat composition suitable for deposition onto metal or
plastic comprising:
(a) about 20 to 80% weight percent based on the final solids
content of said basecoat composition of an anionic polyurethane
principal resin comprised of the reaction product of:
(i) a polyester component comprised of the reaction product of a
carboxylic acid component with an alcohol having at least two
hydroxyl groups wherein said carboxylic acid component is comprised
of at least about 50% by weight of at least one long-chain
carboxylic acid having between 18 and 60 carbon atoms and at most
about 50% of at least one short-chain dicarboxylic acid;
(ii) a multi-functional compound having at least one active
hydrogen and at least one carboxylic acid functionality;
(iii) a compound having at least 2 active hydrogen groups selected
from the group consisting of hydroxyl, sulfhydryl, primary amine,
and secondary amine, one of said primary amines accounting for one
active hydrogen and;
(iv) a polyisocyanate;
(b) about 5 to about 50% by weight of an aminoplast cross-linking
resin;
(c) 5 to about 35 weight percent of a branched chain polyester
resin comprised of the reaction product of:
(i) a polyester component comprised of the reaction product of
(1) a carboxylic acid component comprised of at least 50% by weight
of at least one long chain carboxylic acid containing compound
having between 18 and 60 carbon and not more than 50% by weight of
at least one short-chain dicarboxylic acid; and
(2) an alcohol component having an average functionality of at
least 2; and
(ii) 2-25% by weight of a polyfunctional carboxylic acid or acid
anhydride, said polyfunctional carboxylic acid or acid anhydride
having at least 3 carboxylic acid groups; and
(d) about 2 to 75 weight percent of a pigment-containing grind
resin comprising:
(i) About 6 to about 60% by weight of said pigment-containing grind
resin of a pigment;
(ii) About 20 to about 75% by weight of said pigment-containing
grind resin of a polyurethane resin produced by the reaction
product of:
(1) a polyester resin component produced by the reaction of a
carboxylic acid component comprised of at least 50% by weight of a
long-chain carboxylic acid having between 18 and 60 carbon atoms
and at most about 50% of a short chain dicarboxylic acid and an
alcohol having at least 2 hydroxyl groups; and
(2) a mixture of a multi-functional compound having at least 1
active hydrogen and at least one carboxylic acid functinality, at
least one compound having at least two active hydrogen groups, and
a polyisocyanate, said carboxylic acid groups being neutralized
with an amine; and
(iii) About 20% to about 60% by weight of said pigment-containing
grind resin of an aminoplast cross-linking agent..]. .[.2. The
basecoat composition according to claim 1 wherein said polyurethane
resin is comprised of C.sub.36 dimer fatty acid as the long-chain
carboxylic
acid..]. 3. The basecoat composition according to claim .[.2.].
.Iadd.57 .Iaddend.wherein said long-chain carboxylic acid comprises
about 50 to 80% of the carboxylic acid component used to synthesize
said polyurethane principal resin. .[.4. The basecoat composition
according to claim 3 wherein said long chain carboxylic acid used
to synthesize said polyurethane resin is C.sub.36 dimer fatty
acid..]. .[.5. The basecoat composition according to claim 1
wherein said polyfunctional carboxylic
acid (d) is trimellitic anhydride..]. 6. The basecoat composition
according to claim .[.1.]. .Iadd.60 .Iaddend.wherein said hectorite
clay
is a purified sodium lithium magnesium silicate. 7. The basecoat
composition according to claim .[.1.]. .Iadd.61 .Iaddend.wherein
said fumed silica compound is Aerosil 972 .TM.. .[.8. The basecoat
composition
according to claim 1 wherein said aminoplast is melamine..]. 9. A
branched chain polyester resin for use in basecoat compositions
comprising the reaction product of:
(a) a polyester component comprised of the reaction product of
(i) a carboxylic acid component comprised of at least about 50% by
weight of a long-chain carboxylic acid having between 18 and 60
carbons, no more than about 50% by weight of a short-chain
dicarboxylic acid; and
(ii) an alcohol component having an average functionality of at
least 2; and
(b) between about 2 and 25% by weight of a polyfunctional
carboxylic acid
or acid anhydride having at least 3 carboxylic acid groups. 10. The
polyester resin according to claim 9 wherein said long-chain
carboxylic
acid is C36 dimer fatty acid. 11. The polyester resin according to
claim 9
wherein said short-chain dicarboxylic acid is isophthalic acid. 12.
The polyester resin according to claim .[.11.]. .Iadd.65
.Iaddend.wherein said
polyfunctional carboxylic acid is trimellitic anhydride. 13. The
polyester resin according to claim .[.12.]. .Iadd.66
.Iaddend.wherein said aliphatic
diol is 1,6 hexanediol. 14. A multi-layer paint composition
comprising:
(a) at least one waterborne basecoat composition comprising:
(i) an anionic polyurethane composition comprised of the reaction
product of:
(1) a polyester resin component produced by the reaction of a
carboxylic acid component comprised of at least 50% by weight of at
least one long-chain carboxylic acid having between 18 and 60
carbon atoms, and at most about 50% by weight of a short-chain
dicarboxylic acid and an alcohol having at least 2 hydroxyl groups;
and
(2) a mixture of at least one multi-functional compound having at
least 1 active hydrogen group and at least two active hydrogen
groups, and a polyisocyanate, said carboxylic acid groups being
neutralized with an amine;
(ii) a cross-linking agent;
(iii) a branched chain polyester resin comprised of the reaction
product of:
(1) (A) a polyester component comprised of the reaction product of
a carboxylic acid component comprised of at least 50% by weight of
a long-chain carboxylic acid having between 18 and 60 carbons, no
more than about 50% by weight of a short-chain dicarboxylic acid;
and
(B) an alcohol containing compound having an average alcohol
functionality of at least 2; and
(2) between about 2 and 25% by weight of a poly-functional
carboxylic acid or acid anhydride having at least 3 carboxylic acid
groups;
(iv) a pigment; and
(b) a clear topcoat composition for overcoating said basecoat
composition.
.[.15. The composition according to claim 14 wherein said
long-chain
carboxylic acid is C.sub.36 dimer fatty acid..]. 16. The
composition according to claim .[.15.]. .Iadd.67, 68, or 69
.Iaddend.wherein said cross-linking agent is melamine. .[.17. The
composition according to claim
16 wherein said short chain dicarboxylic acid is isophthalic
acid..]. 18. The composition according to claim 14 wherein said
compound having at least two active .Iadd.hydrogen .Iaddend.groups
.Iadd.of component (a) (i)(2) .Iaddend. is selected from the group
consisting of diols, diamines,
and dithiols. 19. The composition according to claim .[.14.].
.Iadd.74
.Iaddend.wherein said aliphatic diol is 1,6 hexanediol. 20. The
composition according to claim 14 wherein said polyfunctional
carboxylic
acid is trimellitic anhydride. 21. The .[.method.].
.Iadd.composition .Iaddend.according to claim 20 wherein said
long-chain carboxylic acid
.Iadd.of component (a)(i)(1) .Iaddend.is C.sub.36 dimer acid. 22.
The .[.method.]. .Iadd.composition .Iaddend.according to claim
21.Iadd., 75 or 76 .Iaddend.wherein said short-chain dicarboxylic
acid is selected from
the group consisting of adipic acid and isophthalic acid. 23. The
.[.method.]. .Iadd.composition .Iaddend.according to claim 22
wherein said
alcohol having at least 2 hydroxyl groups is 1,6-hexanediol. 24.
The .[.method.]. .Iadd.composition .Iaddend.according to claim 23
wherein said
cross-linking agent is melamine. 25. The .[.method.].
.Iadd.composition .Iaddend.according to claim .[.24.]. .Iadd.79
.Iaddend.wherein said rheology control agent is selected form the
group consisting of fumed
silica compounds, bentonite clays, and hectorite clays. 26. The
.[.method.]. .Iadd.composition .Iaddend.according to claim 25
wherein said
hectorite clay is a purified sodium lithium magnesium silicate. 27.
A method of coating an automobile substrate with a multilayer
coating comprising:
(a) applying to the primed substrate .[.old.]. at least one layer
of a waterborne .[.coating.]. .Iadd.basecoat .Iaddend.composition
comprised of:
(i) a polyurethane resin obtained from the reaction product of:
(1) a polyester resin component produced by the reaction of a
carboxylic acid component comprised of at least 50% by weight of a
long-chain carboxylic acid having between 18 and 60 carbon atoms
and at most about 50% of a short chain dicarboxylic acid and an
alcohol having at least 2 hydroxyl groups; and
(2) a mixture of a multi-functional compound having at least 1
active hydrogen functionality and at least one carboxylic acid
functionality, at least one compound having at least two active
hydrogen groups, and polyisocyanate, said carboxylic acid groups
being neutralized with an amine;
(ii) a cross-linking agent;
(iii) a rheology control agent; and
(iv) a pre-formed branched chain polyester resin comprised of the
reaction product of:
(1) (A) a polyester component comprised of the reaction product of
a carboxylic acid component comprised of at least 50% by weight of
a long chain carboxylic acid having between 18 and 60 carbons, no
more than about 50% by weight of a short-chain dicarboxylic acid
and between about 2 and 25% by weight of a poly-functional
carboxylic acid having at least 3 carboxylic acid groups; and
(B) an alcohol component having an average functionality of at
least 2; and
(2) between about 2 and 25% by weight of a polyfunctional
carboxylic acid having at least 3 carboxylic acid groups,
(b) flash drying said basecoats; and
(c) applying at least one layer of a clear topcoat onto said
basecoat; and
(d) curing said basecoats and topcoat to a hard, durable film. 28.
The method according to claim 27 wherein said long-chain carboxylic
acid is
C.sub.36 dimer fatty acid .Iadd.of component (a)(i)(1).Iaddend..
29. The method according to claim 28.Iadd., 81 or 82
.Iaddend.wherein said short-chain dicarboxylic acid .Iadd.of
component (a)(i)(1) .Iaddend.is
isophthalic acid. 30. The method according to claim 29 wherein
said
alcohol having at least 2 hydroxyl groups is 1,6 hexane diol. 31. A
multi-coated metal or plastic substrate comprising:
a substrate coated with at least one waterborne basecoat
composition comprising:
(a) about 20 to 80% weight percent based on the final solids
content of said basecoat composition of .[.a first.]. .Iadd.an
.Iaddend.anionic polyurethane resin comprised of the reaction
product of:
(i) a polyester component with an alcohol having at least two
hydroxyl groups .[.wherein said.]. .Iadd.and a .Iaddend.carboxylic
acid component .[.is.]. comprised of at least about 50% by weight
of a long-chain carboxylic acid having between 18 and 60 carbon
atoms and at most about 50% of a short chain dicarboxylic acid:
(ii) a multi-functional compound having at least 1 active hydrogen
functionality and at least one carboxylic acid functionality;
(iii) a compound having at least 2 active hydrogen groups;
(iv) a polyisocyanate; and
(v) an amine-containing compound for neutralizing the free
carboxylic acid groups;
(b) about 5 to about 50 weight percent of an aminoplast
cross-linking resin;
(c) about 0.1 to about 25 weight percent of a rheology control
agent, selected from the group consisting of fumed silica
compounds, bentonite clays, and hectorite clays;
(d) about 0 to about 35 weight percent of a branched chain
polyester resin comprised of the reaction product of;
(i) a carboxylic acid component comprised of at least 50% by weight
of a long chain carboxylic acid having between 18 and 60 carbons,
no more than about 48% by weight of a short-chain dicarboxylic acid
and between 2 and 25% by weight of a polyfunctional carboxylic acid
or acid anhydride, said polyfunctional carboxylic acid having at
least 3 carboxylic acid groups; and
(ii) an alcohol component having an average functionality of about
at least 2; and
(e) about 2 to about 75 weight percent of a pigment, each of said
basecoat compositions being flash-dried before being coated with a
clear topcoating, said basecoat composition and said topcoating
being cured to a
hard, durable film. 32. The composition according to claim 31
wherein said long-chain carboxylic acid .Iadd.of component
(a)(i)(1) .Iaddend.is
C.sub.36 dimer acid. 33. The composition according to claim .[.1.].
.Iadd.31 .Iaddend.wherein said polyurethane resin is neutralized
with an
amine. 34. The composition according to claim 33 wherein said amine
is a
tertiary amine. 35. The composition according to claim 14 wherein
said
amine is a tertiary amine. 36. The .[.method.]. .Iadd.composition
.Iaddend.according to claim 21 wherein said amine is a tertiary
amine. .[.37. The method according to claim 21 wherein said
premixed slurry is
further comprised of pigment particles..]. 38. The .[.method.].
.Iadd.composition .Iaddend.according to claim .[.37.]. .Iadd.89
.Iaddend.wherein said pigment particles are selected from the group
consisting of aluminum metal flakes and pigment coated mica
particles
.[.in solvent.].. 39. The method according to claim 27 wherein said
amine is a tertiary amine. .[.40. The method according to claim 27
wherein said first layer composition further comprises a
composition selected from the
group consisting of aluminum, mica, and mixtures thereof..]. 41.
The method according to claim .[.27.]. .Iadd.90 .Iaddend.wherein
said first
layer .[.composition.]. further comprises a branched polyester
resin. 42. The method according to claim .[.40.]. .Iadd.91
.Iaddend.wherein said
first layer further comprises a branched polyester resin. 43. The
method according to claim 31 wherein said amine-containing compound
is a tertiary amine-containing compound. .[.44. The basecoat
composition of claim 1, wherein the rheology control agent is
selected from the group consisting
of fumed silica compounds, bentonite clays, and hectorite clays..].
45. The multi-layer paint composition of claim 14 wherein said
topcoat composition is applied to the uncured basecoat compositions
which have been flash dried at a time and temperature such that the
topcoat can be
applied without an intervening cooldown period. 46. The multi-layer
paint composition of claim 45 wherein the basecoat compositions are
flash dried at a temperature between room temperature and about 145
degrees F. for
between about 30 seconds and about 10 minutes. 47. The multi-coated
metal or plastic substrate of claim 31 wherein the basecoat
compositions are flash dried at a time and temperature such that
the topcoat can be applied
without an intervening cooldown period. 48. The multi-coated metal
or plastic substrate of claim 47 wherein the basecoat
.[.composition.]. .Iadd.compositions .Iaddend.are flash dried at a
temperature between room temperature and about 145 degrees F. for
between about 30 seconds and
about 10 minutes. 49. The basecoat composition of claim .[.1
additionally.]. .Iadd.59 .Iaddend.comprising from about 2 to about
25
weight percent of a rheology control agent. 50. The basecoat
composition of claim 49 wherein the rheology control agent is
selected from the group consisting of fumed silica compounds,
bentonite clays and hectorite clays.
1. A method of making a waterborne basecoat composition for use in
a multi-layer coating comprised of
(A) an anionic polyurethane resin comprised of
(1) a polyester resin component produced by the reaction of a
carboxylic acid component comprised of at least 50% by weight of a
long-chain acid having between 18 and 60 carbon atoms and at most
about 50% of a short-chain dicarboxylic acid and an alcohol having
at least 2 hydroxyl groups; and
(2) a mixture of at least one multi-functional compound having at
least 1 active hydrogen functionality and at least one carboxylic
acid functionality, at leat one compound having at least two active
hydrogen groups, and a polyisocyanate, said carboxylic acid group
being neutralized with an amine,
(B) a crosslinking agent, and
(C) a rheology control agent, comprising the sequential steps
of:
(a) adding the crosslinking agent in solution to the rheology
control agent in solution and thoroughly mixing
.Iadd.and.Iaddend.;
(b) adding an aqueous dispersion of the anionic polyurethane resin
under
agitation and thoroughly mixing. 52. The method of claim 51
comprising the additional sequential step of (c) adding under
agitation and with thourough mixing a premixed slurry comprised
of:
(i) a slurry of mica particles and, optionally, aluminum metal
flakes and (ii) a pre-formed branched chain polyester resin
dispersions, said polyester resin comprised of the reaction product
of:
(1) (A) a polyester component compound of the reaction product of a
carboxylic acid component comprised of at least 50% by weight of a
long chain carboxylic acid having between 18 and 60 carbons, no
more than about 50% by weight of a short-chain dicarboxylic acid
and between about 2 and 25% by weight of a polyfunctional
carboxylic acid having at least 3 carboxylic acid groups; and
(B) an alcohol component having an average functionality of at
least 2; and
(2) between about 2 and 25% by weight of a polyfunctional
carboxylic acid
having at least 3 carboxylic acid groups. 53. The method of claim
52 comprising the additional sequential steps of (d) adding under
agitation and with thorough mixing a pigment-containing grind
resin, and (e)
adjusting the pH and viscosity of the mixture so obtained. 54. The
method of claim 27 wherein the basecoat compositions are flash
dried at a time and temperature such that the topcoat can be
applied without an
intervening cooldown period. 55. The method of claim 54 wherein the
basecoat compositions are flash dried at a temperature between room
temperature and about 145 degrees F. for between about 30 seconds
and
about 10 minutes. .Iadd.56. A basecoat composition for deposition
onto metal or plastic comprising:
(a) about 20 to 80% weight percent based on the final solids
content of said basecoat composition of an anionic polyurethane
resin comprised of the reaction product of:
(i) a polyester component comprised of the reaction product of a
carboxylic acid component with an alcohol having at least two
hydroxyl groups wherein said carboxylic acid component is comprised
of at least about 50% by weight of at least one long-chain
carboxylic acid having between 18 and 60 carbon atoms and at most
about 50% of at least one short-chain dicarboxylic acid;
(ii) a multifunctional compound having at least one active hydrogen
and at least one carboxylic acid functionality;
(iii) a compound having at least 2 active hydrogen groups selected
from the group consisting of hydroxyl, sulfhydryl, primary amine
and secondary amine, one of said primary amines accounting for one
active hydrogen and
(v) a polyisocyanate;
(b) about 5 to about 50% by weight of an aminoplast cross-linking
resin;
(c) 5 to about 35 weight percent of a branched chain polyester
resin comprised of the reaction product of:
(i) a polyester component comprised of the reaction product of:
(1) a carboxylic acid component comprised of at least 50% by weight
of at least one long chain carboxylic acid containing compound
having between 18 and 60 carbons and not more than 50% by weight of
at least one short-chain dicarboxylic acid, and
(2) an alcohol component having an average functionality of at
least 2; and
(ii) 2 to 25% by weight of a polyfunctional carboxylic acid or acid
anhydride, said polyfunctional carboxylic acid or acid anhydride
having at least 3 carboxylic acid groups; and
(d) about 2 to 75 weight percent of pigment-containing grind resin
comprising:
(i) about 6 to about 60% by weight of said pigment-containing grind
resin of a pigment;
(ii) about 20 to about 75% by weight of said pigment-containing
grind resin of a polyurethane resin produced by the reaction
product of:
(1) a polyester resin component produced by the reaction of a
carboxylic acid component comprised of at least 50% by weight of a
long-chain carboxylic acid having between 18 and 60 carbon atoms,
and at most about 50% of a short-chain dicarboxylic acid, and an
alcohol having at least 2 hydroxyl groups; and
(2) a mixture of a multifunctional compound having at least 1
active hydrogen and at least one carboxylic acid functionality, and
at least one compound having at least two active hydrogen groups,
and a polyisocyanate, said at least one carboxylic acid
functionality being neutralized with amine; and
(iii) about 20% to about 60% by weight of said pigment-containing
grind
resin of an aminoplast cross-linking agent. .Iaddend. .Iadd.57. The
basecoat according to claim 56, wherein the long-chain carboxylic
acid contained in the polyurethane resin of component (a) is
comprised of C.sub.36 dimer fatty acid. .Iaddend. .Iadd.58. The
basecoat composition according to claim 56 wherein the
multifunctional compound of component (d)(ii)(2) is trimellitic
anhydride. .Iaddend. .Iadd.59. The basecoat composition according
to claim 56 further comprising a rheology control
agent. .Iaddend. .Iadd.60. The basecoat composition according to
claim 59 wherein the rheology control agent is hectorite clay.
.Iaddend. .Iadd.61. The basecoat composition according to claim 59
wherein the rheology control agent is a fumed silica compound.
.Iaddend. .Iadd.62. The basecoat composition of claim 57 wherein
the aminoplast cross-linking agent of component (b) is an aldehyde
condensation product of melamine. .Iaddend. .Iadd.63. The basecoat
composition of claim 57 wherein the aminoplast cross-linking agent
of component (d)(iii) is an aldehyde condensation product of
melamine. .Iaddend. .Iadd.64. The basecoat composition of claim 57
wherein the aminoplast cross-linking resin of components (b) and
(d)(iii) is an aldehyde condensation product melamine. .Iaddend.
.Iadd.65. The polyester resin of claim 9 wherein component (b) is a
polyfunctional carboxylic acid. .Iaddend. .Iadd.66. The polyester
resin of claim 9 wherein the alcohol component is an aliphatic
diol. .Iaddend. .Iadd.67. The composition of claim 14 wherein the
long-chain carboxylic acid of component (a)(i)(1) is C.sub.36
dimeter acid. .Iaddend. .Iadd.68. The composition of claim 14
wherein the long-chain carboxylic acid of component (a)(iii)(1)(A)
is C.sub.36 dimer acid. .Iaddend. .Iadd.69. The composition of
claim 14 wherein the long-chain carboxylic acid of component
(a)(i)(1) and of component (a)(iii)(1)(A) is C.sub.36 dimer acid.
.Iaddend. .Iadd.70. The composition of claim 67, 68, or 69 wherein
the short-chain dicarboxylic acid of component (a)(i)(1) is
isophthalic acid. .Iaddend. .Iadd.71. The composition of claim 67,
68, or 69 wherein the short-chain dicarboxylic acid of component
(a) (iii)(1)(A) is isophthalic acid. .Iaddend. .Iadd.72. The
composition of claim 67, 68 or 69 wherein the short-chain
dicarboxylic acid of component (a)(i)(1) and of component
(a)(iii)(1)(A) is isophthalic acid. .Iaddend. .Iadd.73. The
composition of claim 14 wherein the alcohol containing compound
of
component (a)(iii)(1)(B) is an aliphatic diol. .Iaddend. .Iadd.74.
The composition according to claim 20 wherein said long-chain
carboxylic acid of component (a)(iii)(1)(A) is C.sub.36 dimer acid.
.Iaddend. .Iadd.75. The composition of claim 20 wherein the
long-chain carboxylic acid of components (a)(i)(1) and
(a)(iii)(1)(A) is C.sub.36 dimer acid. .Iaddend. .Iadd.76. The
composition according to claim 21, 74 or 75 wherein said
short-chain dicarboxylic acid of component (a)(iii)(1)(A) is
selected from adipic acid and isophthalic acid. .Iaddend. .Iadd.77.
The composition according to claim 21, 74 or 75 wherein said
short-chain dicarboxylic acid of components (a)(i)(1) and
(a)(iii)(1)(A) is selected from adipic acid isophthalic acid.
.Iaddend. .Iadd.78. The composition of claim 24 further comprising
a rheology control agent. .Iaddend. .Iadd.79. The method of claim
27 wherein said long-chain carboxylic acid of component
(a)(iv)(1)(A) is C.sub.36 dimer acid. .Iaddend. .Iadd.80. The
method of claim 27 wherein the long-chain carboxylic acid of
components (a)(i)(1) and (a)(iv)(1)(A) is C.sub.36 dimer acid.
.Iaddend. .Iadd.81. The method of claim 28, 79 or 80 wherein said
short-chain dicarboxylic acid of component (a)(iv)(1)(A) is
isophthalic acid. .Iaddend. .Iadd.82. The method of claim 28, 79 or
80 wherein the short-chain dicarboxylic acid of components
(a)(i)(1) and (a)(iv)(1)(A) is isophthalic acid. .Iaddend.
.Iadd.83. The method according to claim 81 wherein the alcohol
having at least 2 hydroxyl groups is 1,6-hexanediol. .Iaddend.
.Iadd.84. The method according to claim 82 wherein the alcohol
having at least 2 hydroxyl groups is 1,6-hexanediol. .Iaddend.
.Iadd.85. The composition according to claim 31 wherein said
long-chain carboxylic acid of component (d)(i) is
C.sub.36 dimer acid. .Iaddend. .Iadd.86. The composition according
to claim 31 wherein said long-chain carboxylic acid of components
(a)(i)(1) and (d)(i) is C.sub.36 dimer acid. .Iaddend. .Iadd.87.
The composition according to claim 21 wherein the pigment particles
are in the form of a premixed slurry. .Iaddend. .Iadd.88. The
method of claim 27 wherein the at least one layer of a waterborne
basecoat composition is further comprised of a first layer and at
least one other layer. .Iaddend. .Iadd.89. The method of claim 88
wherein the first layer of the at least one layer of a waterborne
coating composition further comprises aluminum, mica or a mixture
thereof. .Iaddend.
Description
BACKGROUND OF THE INVENTION
Multi-layer systems have been utilized to coat automobiles for a
number of years, but the early development of these systems
necessarily employed organic solvents. As environmental regulations
became more stringent, and the cost or organic solvents rose,
organic-borne basecoat systems became less desirable. The recent
research emphasis in the area of multi-layer systems, especially
basecoat systems has focused on the development of water-borne
systems for multi-layer coatings.
The shift from organic solvents to water for dispersing and
applying resins in multi-layer systems solved many of the
environmental and cost problems associated with the use of organic
solvents. Water-borne systems, however, have resulted in other
problems.
The application of a multi-layer coating to an automobile body, for
example, would be greatly facilitated by a system that provides for
quick-drying of solvent during and after the application of a
coating. These quick-drying characteristics enhance a broad
application window and allow minimal control of relative humidity
and temperature in the spray zone, resulting in lower energy costs.
By facilitating drying, the time between coatings would be
diminished, resulting in greater manufacturing efficiencies and
lower energy costs. In addition, there would be no need for a
cooldown zone after drying which would further the manufacturing
efficiencies. Low boiling organic solvents were originally used in
multi-layer coatings to take advantage of their quick-drying
features. With the introduction of aqueous based multi-layer
systems, the drying of water from a given resin coating after
application because a problem. It was desired to produce a basecoat
composition that could be dried in a period of time short enough to
maintain manufacturing efficiency.
The present invention is directed to polyurethane coatings to be
used in formulating basecoat compositions of multi-layer coating
systems. The resins of this invention are shown to possess the
qualities of being quick-drying during and after application.
Furthermore, the resins of this invention also exhibit superior
coating characteristics, for example, good metallic effects such as
very favorable arrangement, fixation, and flip effect of the
metallic pigments in the paint film. When non-metallic pigments are
used, the resins of the present invention exhibit excellent
decorative effect.
This invention, therefore, relates to the field of polyurethane
coatings for use in automobile basecoat/clearcoat systems. In
particular, this invention relates to the discovery that
incorporating a long-chain carboxylic acid of at least 50% by
weight of the carboxylic acid component used to make polyester
resins which are further incorporated into polyurethane resins
provides basecoat compositions exhibiting low temperature flash
characteristics. These low temperature flash characteristics are
exhibited even where the basecoats are deposited at 50-90% relative
humidity.
The polyurethane resin, produced by the reaction of the
above-described polyester resin and a polyisocyanate mixture,
although useful as a coating composition for a number of substrates
of especially useful as a basecoat for automobiles. Coatings
containing polyurethanes synthesized from polyesters with a long
chain fatty acid comprising at least about 50% of the acid
component in the polyester resin have shown to be particularly
useful for water-borne basecoat compositions used in multi-layer
systems.
It is an object of this invention to provide polyurethane resins
that can be incorporated into basecoat formulations to provide low
flash and quick-drying characteristics.
It is an additional object of this invention to provide polyester
resins which can provide favorable low flash and quick-drying
characteristics to polyurethane resins.
It is a further object of this invention to provide water-borne
basecoat compositions having favorable coating and cosmetic
characteristics and additionally provide for manufacturing
efficiencies which result from the low-flash, quick-drying
characteristics.
It is also an object of this invention to provide a method of
producing the resins and basecoat compositions described
herein.
It is a further object of this invention to provide a method for
coating a metallic or plastic substrate utilizing the resins and
basecoat formulations of the present invention.
These and other objects of the present invention are furthered by
incorporating polyurethane resins into basecoat formulations.
SUMMARY OF THE INVENTION
The polyurethane resins are comprised of, in part, polyester resins
from a carboxylic acid component and a alcohol having at least 2
hydroxyl moeities. Specifically, this invention relates to an
anionic polyurethane coating compositions comprised of:
1. A polyester component produced by condensing a carboxylic acid
component with alcohols having at least 2 hydroxy moeities wherein
the carboxylic acid component is comprised of at least about 50% by
weight of a long chain hydrophobic carboxylic acid containing
compound having between 18 to 60 carbon atoms; and
2. A mixture of a compound having at least 2 isocyanate groups, a
multi-functional compound having at least one active hydrogen
functionality and at least one carboxylic acid functionality and
optionally, a compound having at least two active hydrogen groups,
for example, diols, dithiols, diamines, or compounds having
mixtures of these active hydrogen groups, the polyester component
described above being reacted with this mixture to produce a
polyurethane resin containing free carboxylic acid groups. The free
carboxylic acid groups may be neutralized to produce a
water-dispersible polyurethane resin.
The polyurethane resin described above can be formulated as a
water-dispersed basecoat resin along with a grind resin, a
cross-linking agent, thixotropic or rheology control agents,
thickeners, pigments, aluminum and/or mica particles, basifying
agents, water, fillers, surfactants, stabilizers, plasticizers,
wetting agents, dispersing agents, adhesion promoters, defoamers,
catalysts, and additional polymers, for example a branch-chain
polyester among other ingredients.
After formulation, the basecoat composition can be sprayed or
electrostatically deposited onto the automobile body, preferably,
in one or two coats. Generally, two even coats of basecoat are
applied with a one minute flash between coats. After deposition of
the basecoat, before application of a high solids content clear
coat, it is generally preferred to flash about 90% of the water
from the basecoat for optimum appearance and to eliminate water
boil of the clearcoat.
A preferred embodiment of the water-dispersible anionic resin
relates to a polyurethane product wherein the polyurethane is
formed with a mixture of an excess of diisocyanate, a
multi-functional compound having at least one active hydrogen
functionality and at least one carboxylic acid, functionality and a
hydroxy terminated polyester resin. This mixture produces a
urethane-containing resin intermediate having one or two free
isocyanate groups per polymer chain. In especially preferred
embodiments, the free isocyanate groups are than capped with an
excess of an alcohol having a hydroxy functionality of at least one
and preferably, two or more.
The polyester component is preferably formed from an alcohol
component having at least about 2 hydroxy groups per molecule
(polyol) and a carboxylic acid component. The carboxylic acid
component is comprised of at least about 50% by weight of a long
chain carboxylic acid containing compound having between 18 and 60
carbon atoms in the chain. This long-chain carboxylic acid
component is an alkyl, alkylene, aralkyl, aralkylene, or compound
of similar hydrophobicity having 18 and 60 carbons in the chain.
The polyester chain may be branched, but it is preferred that
chain-branching be kept to a minimum. It is recognized that low
flash and quick-drying characteristics of the basecoat compositions
of this invention are the result of having a high percentage of
highly hydrophobic groups in the polyester resins. C18 to C60
carboxylic acid present a range of compounds having suitable
hydrophobicity. Most preferably, this long chain carboxylic acid is
a dicarboxylic acid and most preferably is a C.sub.36 dicarboxylic
acid known as a dimer acid. The remaining carboxylic acid component
may be comprised of a short-chain monocarboxylic or dicarboxylic
acid component, preferably a dicarboxylic acid. When monocarboxylic
acid compounds are used, these function as polyester chain
terminators. Thus, where high molecular weight polyesters are
desired, the amount of monocarboxylic acid is kept to a minimum.
The short-chain dicarboxylic acid may be preferably short-chain
alkyl or alkalyne dicarboxylic acid, for example, azeleic acid,
adipic acid, or an equivalent aliphatic dicarboxylic acid or an
aromatic dicarboxylic acid. Most preferably, the aromatic
dicarboxylic acid is isophthalic acid. It must be stressed that
while a number of short-chain carboxylic acid compounds may be
used, the ultimate goal is to maintain the hydrophobic, quick-flash
characteristics of the polyester resin.
The polyester resins described hereinabove are useful on virtually
any elastomeric substrate and are particularly useful when
formulated into polyurethane coatings and used in basecoat
formulations for deposition onto metal or plastic substrates,
especially automobile bodies. The polyurethane resins synthesized
from the above-described polyesters exhibit quick-drying, low flash
characteristics. These polyurethane resins are, of course, useful
in embodiments where quick-drying, low-flash characteristics are
required. These resins have shown particular utility as a basecoat
in a multi-layer basecoat/clear coat automobile coating system.
The composition of the carboxylic acid component and polyol
component employed to synthesize the polyester resins is such as to
provide an excess of the polyol over and above the total number of
equivalents of acid present in the mixture. In other words, the
reactants should be selected, and the stoichiometric proportions of
the respective acid and polyol components be adjusted to give
hydroxy-terminated, polyester molecules each theoretically having a
hydroxyl functionality of 2 or more.
As stated above, the acid mixture employed in forming the polyester
intermediate most preferably contains a C.sub.36 dicarboxylic acid
product known as dimer acid. Processes for forming this acid are
well known and form the subject of numerous U.S. patents including
U.S. Pat. Nos. 2,482,761, 2,793,220, 2,793,221 and 2,995,121 or
alternatively dimer fatty acid can be purchased from a chemical
supply house (Empol 1010, available from Emery Chemical Co.).
C.sub.36 dimer fatty acid fraction consists essentially of dimer
(C.sub.36 dicarboxylic acids) together with amounts up to about
20-22% of C.sub.54 trimer. However, those of skill in the art refer
to this dimer-trimer mixture as "dimer", and this practice is
followed herein. The preferred grade contains 97% dimer and 3%
trimer. These polymerization reaction products can be used in the
form in which they are recovered from the polymerization unit, or
they can be given a partial or complete hydrogenation treatment to
reduce unsaturation before being reacted with the polyol compound
to form the polyester. Polyesters so formed can then be used to
form a polyurethane resin which can be used in basecoat
formulations exhibiting low flash, quick-drying
characteristics.
The polyurethanes of the present invention are advantageously
storage stable and are, of course, water dispersible. The water
dispersibility of the resins is controlled by the amount of free
carboxylic acid contained in the final resin particles, and the
number of salts groups formed from those free acid groups.
Coating compositions produced using the polyurethane resins
described herein have exhibited low flash and quick drying
characteristics surprising for a water-dispersible resin.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a water soluble anionic
polyurethane resin produced by reacting a polyester component
comprised of at least 50% by weight of the carboxylic acid
component of a long chain carboxylic acid containing compound with
a mixture of a polyisocyanate-containing compound, a
multifunctional compound having at least one active hydrogen
functionality and at least one carboxylic acid functionality, and
optionally, an additional component comprising a compound having at
least two active hydrogen containing moieties. The resulting
polyurethane intermediate has terminal isocyanate groups or active
hydrogen-containing moieties, depending upon the stoichiometry of
the polyester mixture described above.
An especially preferred embodiment of the polyurethane resins of
the present invention relates to the formation of a urethane
product in which the intermediate polyurethane resin described
above has free isocyanate groups at the terminal positions of the
polyurethane resin. The isocyanate groups are then capped with an
excess of a polyfunctional alcohol having at least 2 alcohol
groups, and preferably at least 3 alcohol groups.
The particular characteristics of the polyurethane resins are
determined by the components of the polyester resin. It has
unexpectedly been discovered that polyester resins produced from a
carboxylic acid component comprised of at least about 50% by weight
of a long fatty acid or dicarboxylic acid having between about 18
and 60 carbon atoms can be formulated into water-dispersible
polyurethane coating resins exhibiting particularly favorable low
flash and quick drying properties for water borne basecoat
resins.
The acid component of the polyester is, of course, critical to the
invention and is comprised of a mixture of at least about 50% by
weight of a long chain carboxylic acid component having between 18
and 60 carbon atoms. Preferably, the long chain carboxylic acid is
a dicarboxylic acid and most preferably, the dicarboxylic acid is a
C.sub.36 dimeric dicarboxylic acid or dimer acid. Where the long
chain carboxylic acid comprises less than 100% of the carboxylic
acid component, the carboxylic acid component is also comprised of
one or more short-chained carboxylic acids.
Preferably, the long chain fatty acid comprises between about 50
and 80% by weight of the acid component of the polyester polyol. In
the principal resin (major vehicle) the long chain fatty acid
component comprises about 75-80% of the a long chain fatty acid
component and in the grind resin, the polyester resin comprises
about 50% by weight of the polyester resin. Generally, the higher
the percentage of long chain carboxylic acid, the better the
quick-drying or flash off characteristics of the final polyurethane
resin. However, the advantageous flash-off characteristics must be
balanced with the effect that the change in the carboxylic acid
component has on the metallic effects, durability and other
characteristics of the resin, including, in the case of grind
resin, the ability to accomodate pigment.
The shorter chain carboxylic acid component is comprised of a
mono-, di- or higher functionality carboxylic acid or a mixture of
these carboxylic acids having carbon chains of 12 or fewer carbon
units. Monocarboxylic acids function to terminate a polyester and
are chosen for that purpose. It is preferable that the short chain
carboxylic acid component be a dicarboxylic acid. Such preferred
dicarboxylic acid compounds include, for example, adipic, azeleic,
and other aliphatic dicarboxylic acids. Aromatic dicarboxylic acids
may also be preferred. As especially preferred aromatic
dicarboxylic acid is isophthalic acid. Alkylene and aralkylene
carboxylic acids can also be used. Where branch chains in the
polyester are desired, a carboxylic acid containing three or more
carboxylic acid groups, for example citric acid, is used. A
preferred acid of this type is trimellitic anhydride.
The polyester resins are synthesized from the above-described
carboxylic acid component and an excess of a polyol component. An
excess of polyol is used so that the polyester resin preferably
contains terminal hydroxyl groups. The polyol compounds preferably
have an average hydroxy-functionality of at least 2.
The polyester resin in most cases is comprised of one or more
polyols, preferably a diol. Up to about 25 percent by weight of the
polyol component may be a polyol having three or more hydroxyl
groups per molecule. Where polyols having three or more hydroxy
groups are chosen, the result is a branched polyester.
While it is not always desirable to have a triol or higher
multi-functional alcohol present because of the tendency to form a
branched chain polyester, some branching may be desirable. The
polyester resin should not be highly branched, however. There may
also be present a small amount of monoalcohol, in the polyol
component, particularly if larger proportions of higher functional
alcohols are used. These monoalcohols serve as chain terminators.
In certain instances, for example, where certain high molecular
weight polyols are used, the polyols can be largely or even
entirely made up of compounds of functionality greater than
two.
The diols which are usually employed in making the polyester resins
include alkylene glycols, such as ethylene glycol, propylene
glycol, butylene glycol, and neopentyl glycol, 1,6 hexanediol and
other glycols such as hydrogenated bisphenol A, cyclohexane
dimethanol, caprolactone diol (i.e., the reaction product of
caprolactyone and ethylene glycol), hydroxyalkylated bisphenols,
and the like. However, other diols of various types and, as
indicated, polyols of higher functionality may also be utilized.
Such higher functional alcohols can include, for example,
trimethylolpropane, trimethylolethane, pentaerythritol, and the
like, as well as higher molecular weight polyols.
The low molecular weight diols which are preferred in the instant
invention are known in the art. They have hydroxy values of 200 or
above, usually within the range of 2000 to 200. Such materials
include aliphatic diols, particularly alkylene polyols containing
from 2 to 18 carbon atoms. Examples include ethylene glycol,
1,4-butanediol, cycloaliphatic diols such as 1,2 cyclohexanediol
and cyclohexane dimethanol. An especially preferred diol is 1,6
hexanediol.
The resulting polyester resin is preferably produced with dimer
fatty acid as the long chain carboxylic acid, isophthalic acid as
the minor short-chain carboxylic acid component component and an
excess of 1,6 hexane diol so that the resulting polyester polyol
ranges in size between about 200 and 2000 grams per equivalent of
hydroxyl. Preferably, the polyester resin has a range between 700
and 800 grams per equivalent of hydroxyl and most preferably, has
about 750 grams per equivalent of hydroxyl.
To produce the polyurethane resins which are useful in basecoat
compositions of the present invention, the above-described
polyester polyol is reacted with a mixture of a polyisocyanate, a
multi-functional compound having at least one active hydrogen group
and at least one carboxylic acid group, and optionally, a component
comprising a chemical compound having at least two active hydrogen
groups, but no carboxylic acid groups.
The polyester, polyisocyanate and multi-functional compound may
also be reacted in the same pot, or may be reacted sequentially,
depending upon the desired results. Sequential reaction produces
resin which are more ordered in structure. Both the polyester and
multi-functional compound may serve as chain extenders to build up
the polyurethane backbone through reaction of hydroxyl groups with
isocyanate groups. However, to function as a chain extender, the
multi-functional compound must have at least two active hydrogen
groups. Where the multi-functional compound has only one active
hydrogen group, the result is chain termination. Additional chain
extenders having at least two active hydrogen groups but no
carboxylic acid groups may be added to increase the chain length or
to change the chemical characteristics of the polyurethane resin.
In general, an excess of polyisocyanate is used so that an
intermediate polyurethane resin can be produced having free
isocyanate groups at the terminal ends. The free isocyanate groups
may then be preferably capped with trimethylol propane or
diethanolamine.
The organic polyisocyanate which is reacted with the polyhydric
material as described is essentially any polyisocyanate and is
preferably a diisocyanate, e.g., hydrocarbon diisocyanates or
substituted hydrocarbon diisocyanates. Many such organic
diisocyanates are known in the art, including p-phenylene
diisocyanate, biphenyl 4,4'diisocyanate, toluene diisocyanate,
3,3'-dimethyl-4,4 biphenylene diisocyanate, 1,4-tetramethylene
diisocyanate, 1,6-hexamethylene diisocyanate,
2,2,4-trimethylhexane-1,6-diisocyanate, methylene bis (phenyl
isocyanate), 1,5 naphthalene diisocyanate, bis(isocyanatoethyl
fumarate), isophorone diisocyanate (IPDI) and methylene-bis- (4
cyclohexylisocyanate). There can also be employed
isocyanateterminated adducts of polyols, such as ethylene glycol,
or 1,4-butylene glycol, trimethylolpropane etc. These are formed by
reacting more than one mol. of a diisocyanate, such as those
mentioned, with one mol, of polyol to form a longer chain
diisocyanate. Alternatively, the polyol can be added along with the
diisocyanate.
While diisocyanates are preferred, other multifunctional
isocyanates may be utilized. Examples are 1,2,4-benzene
triisocyanate and polymethylene polyphenyl isocyanate.
It is preferred to employ an aliphatic diisocyanate, since it has
been found that these provide better color stability in the
finished coating. Examples include 1,6-hexamethylene diisocyanate,
1,4-butylene diisocyanate, methylene bis(4-cyclohexyl isocyanate)
and isophorone diisocyanate. Mixtures of diisocyanates can also be
employed.
The proportions of the diisocyanate, polyester, and
multi-functional compound are chosen so as to provide an isocyanate
terminated intermediate polyurethane resin. This can be
accomplished by utilizing a stoichiometric excess of
polyisocyanate, i.e., more than one isocyanate group per
nucleophilic moiety (reactive with isocyanate) in the other
components.
For purposes of promoting water-solubility it is important to build
acid groups into the polyurethane. For example, the presence of
acid groups is capable of rendering the composition
water-dilutable.
The acids that are employed to provide free acid groups in the
polyurethane resins of this invention are readily available. They
contain at least one active hydrogen group and at least one
carboxylic acid functionality. The active hydrogen group may be a
thiol, a hydroxyl or an amine, with primary amines being considered
to have one active hydrogen group. Examples of such compounds
include hydroxyl carboxylic acids, amino acids, thiol acids,
aminothiol acids, alkanolamino acids, and hydroxythiol acids.
Compounds containing at least 2 hydroxyl groups and at least one
carboxylic acid are preferred. They can be prepared from an
aldehyde that contains at least two hydrogens in the alpha
position. Such aldehydes are reacted in the presence of a base
catalyst with two equivalents of formaldehyde to form an
2.2-hydroxymethyl aldehyde. The aldehyde is then gently oxidized to
the acid by known procedures. The acids that are employed in the
invention can be represented in simplification by Formula I:
##STR1## wherein R represents hydroxymethyl, hydrogen, or alkyl of
up to 20 carbon atoms and preferably up to 8 carbon atoms.
Specific illustrative examples of such acids that are employed in
the invention includes 2,2-di(hydroxymethyl) acetic acid,
2,2,2-tri(hydroxymethyl) acetic acid, 2,2-di(hydroxymethyl)
propionic acid, 2,2-di(hydroxymethyl)butyric acid,
2,2-di(hydroxymethyl)pentanoic acid, and the like. The preferred
acid is 2,2-di(hydroxymethyl) propionic acid.
Longer-chain polyurethane resins can be obtained by chain extending
the polyurethane chain with a compound or mixture of compounds
containing at least two active hydrogen groups but having no
carboxylic acid group, for example diols, dithiols, diamines, or
compounds having a mixture of hydroxyl, thiol, and amine groups,
for example, alkanolamines, aminoalkyl mercaptans, and hydroxyalkyl
mercaptans, among others. For purposes of this aspect of the
invention both primary and secondary amine groups are considered as
having one active hydrogen. Alkanolamines, for example,
ethanolamine or diethanolamine, are preferably used as chain
extenders, and most preferably a diol is used. Examples of
preferred diols which are used as polyurethane chain extenders
include 1,6 hexane diol, cyclohexanedimethylol, and 1,4-butanediol.
A particularly preferred diol is neopentylglycol. Of course, the
same diols used to synthesize the polyester component of the
polyurethane resins can be utilized here as well. While polyhydroxy
compounds containing at least three hydroxyl groups may be used as
chain extenders, the use of these compounds produces branched
polyurethane resins. For purposes of the present invention, it is
preferred to minimize the amount of branching in the polyurethane
resin. Therefore, if polyhydroxy compounds are used, they are
preferably limited to a very minor component of the polyurethane
producing mixture. These higher functional polyhydroxy compounds
include, for example, trimethylolpropane, trimethylolethane,
pentaerythritol, among other compounds.
The polyurethane resin may be chain extended in any manner using
these compounds having at least two active hydrogen groups. Thus,
these compounds may be added to the mixture of polyisocyanate,
polyester and multi-functional compound, or alternatively, may
react at an intermediate stage, to link two free isocyanate groups
that are present at the terminal ends of an intermediate
polyurethane resin.
It is generally preferred that an intermediate polyurethane resin
produced by reacting the polyester resin and the mixture of
polyisocyanate, multifunctional compound containing at least 2
hydroxyl groups and one carboxylic acid group, and chain extender
be terminated with free isocyanate groups. To accomplish this, an
excess of the polyisocyanate component is used. Of course, the
molar ratio of the other components will be adjusted according to
the desired characteristics of the intermediate and final
polyurethane resins. The polyester component comprises no more than
about 80% by weight of the reaction mixture and it is preferred
that the polyester component comprises from about 20% to about 70%
by weight of reactants in the mixture.
In one especially desirable embodiment of the invention, a
multi-functional alcohol is used to terminate the reaction (cap the
free isocyanate groups) at the desired stage (determined by the
viscosity and isocyanate groups present), thereby also contributing
residual hydroxyl groups. Particularly desirable for such purposes
are aminoalcohols, such as ethanolamine, diethanolamine and the
like, since the amino groups preferentially react with the
isocyanate groups present. Multi-functional alcohols, such as
ethylene glycol, trimethylolpropane and hydroxyl-terminated
polyesters, can also be employed in this manner.
While the ratios of the components of the polyester, the
multi-functional isocyanate and the terminating agent can be
varied, it will be noted by those skilled in the art that the
amounts should be chosen so as to avoid gellation and to produce an
ungelled, urethane reaction product containing hydroxyl groups. The
hydroxyl value of the urethane reaction product should be at least
5 and preferably about 20 to about 200.
The amount of polyisocyanate used in the mixture is preferably
between about 20% and 30% by weight of the reactants in the
mixture, but will vary depending upon the polyester used, the acid
number of the final polyurethane resin, and the desired molecular
weight of the final polyurethane resin. The amount of
polyisocyanate will also vary depending upon whether it is desired
to have the intermediate polyurethane terminated with free
isocyanate groups or with hydroxyl groups. Thus, where it is
preferred to terminate the intermediate polyurethane resin with
free isocyanates for capping with trimethylolpropane or
diethanolamine, an excess of polyisocyanate may be used. Where the
intermediate polyurethane resin is to be terminated by hydroxyl
groups, a stoichiometric deficiency of polyisocyanate may be
used.
The amount of multi-functional component having at least one active
hydrogen group and at least one carboxylic acid group also may vary
depending upon the desired acid number of the final polyurethane
resin. The final polyurethane resin has an acid number of at least
about 10, and the amount of this multi-functional component
comprises between about 1% and about 25% by weight of the reactants
of polyurethane producing reaction mixture (polyisocyanate,
polyester, multifunctional compound, and optionally other chain
extenders, for example compounds having two active hydrogens but no
carboxylic groups). It is preferable that the acid number be
higher, because as the acid number increases, the
water-dispersibility of the polyurethane resin potentially
increases. The practical upper limit of acid number is that which
negatively effects the low flash or quick-drying characteristics
and physical properties of the final resin. Of course, the upper
limit of the acid number will vary depending upon the chemical
composition of the final polyurethane resin, but an acid number
with an upper limit of about 100 is, in general, the practical
limit of polyurethane resins of the present invention.
The amount of chain extender, when used producing the polyurethane
resin, varies between about 2% and 25% by weight of the reactants.
The amount used will depend upon the amount of chain extension
desired and the desired size of a polyurethane molecule.
After the polyurethane resin is synthesized, the free carboxylic
acid groups are neutralized with base to form salt groups.
Preferably, the base is an amino containing compound. Tertiary
amines are generally preferred over primary and secondary amines
because of the tendency of the primary and secondary amines to
react with aminoplast cross-linking agents. Preferred tertiary
amines include tri-alkylamines, for example, trimethyl and
triethylamine. Also preferred is triethanolamine. Particularly
preferred is dimethylethanolamine.
The polyurethane resins of the present invention are formulated,
along with other components, into water dispersible basecoat
compositions which are sprayed or electrostatically deposited onto
metal or plastic substrates, for example, automobile bodies. In
general, a polyurethane resin formulated as described herein, is
mixed with an aminoplast resin, pigments a grind resin, water, a
portion of an organic solvent, aluminum and/or mica particles and a
rheology control agent. Other agents may be included, for example,
various fillers, surfactants, plasticizers, stabilizers, wetting
agents, dispersing agents, defoamers, adhesion promoters and
catalysts in minor amounts. In one preferred embodiment a
branched-chain polyester component is also added to the basecoat
composition.
As indicated, an aqueous dispersion of the polyurethane resin is
utilized as the principal or major vehicle resin. In general, the
principal or major vehicle resin comprises between about 20 and 80%
by weight of the total solids present in the basecoat composition.
The preferred polyurethane resin is a resin produced from a
polyester synthesized from dimer fatty acid, isophthalic acid, and
1,6 hexanediol. The resulting polyester is then reacted with a
diisocyanate of isophorone, dimethylol propionic acid and a diol,
for example, neopentyl glycol. The resulting polyurethane
intermediate having free isocyanate groups is then reacted with
trimethylolpropane to cap these groups.
The polyurethane reaction product as described above is mixed with
an aminoplast resin. Aminoplast resins are aldehyde condensation
products of melamine, urea, and similar compounds. Products
obtained from the reaction of formaldehyde with melamine, urea or
benzoguanamine are most common and are preferred herein. However,
condensation products of other amines and amides can also be
employed, for example, aldehyde condensates of triazines, diazines,
triazoles, guanidines, guanamines and alkyl and aryl substituted
derivatives of such compounds, including alkyl and aryl substituted
ureas and alkyl and aryl substituted melamines. Some examples of
such compounds are N,N'-dimethylurea, benzourea, dicyandiamide,
formoguanamine acetoguanamine, ammeline,
2-chloro-4,6-diamino-1,3,5-triazine,
6-methyl-2,4-diamino,1,3,5-triazine, 3-5-diamino-triazole,
triaminopyrimidine, 2-mercapto-4,6-diaminopyrmidine, 2,4,6-triethyl
triamino-1,3,5-triazine, and the like.
While the aldehyde employed is most often formaldehyde, other
similar condensation products can be made from other aldehydes, for
example, acetaldehyde, crotonaldehyde acrolein, benzaldehyde,
furfural, and others.
The amine-aldehyde condensation products contain methylol or
similar alkylol groups, and in most instances at least a portion of
these alkylol groups are etherified by a reaction with an alcohol
to provide organic solvent-soluble resins. Any monohydric alcohol
can be employed for this purpose, including such alcohols as
methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol
and others, as well as benzyl alcohol and other aromatic alcohols,
cyclic alcohols, for example, cyclohexanol, monoethers or glycols
such as Cellosolves and Carbitols .TM. (Union Carbide), and
halogen-substituted or other substituted alcohols, such as
3-chloropropanol. The preferred amine-aldehyde resins are
etherified with methanol or butanol.
A grind resin is also used in the basecoat compositions of the
present invention. While the pigment resin may be comprised of a
number of water soluble polyurethane resins, it is preferred that
the grind resin be similar in chemical character to the principal
or major vehicle resin, i.e., contain a polyester resin component
comprised of a carboxylic acid component comprised of at least
about 50% by weight of a C18 to C60 carboxylic acid, preferably a
dicarboxylic acid. The grind resin may range between about 2 and
about 75% by weight of the total solids in the coating composition
and will vary depending on the desired color and preferably
comprises about 5-40% by weight of the basecoat composition.
A preferred anionic polyurethane resin for use as a grind resin in
embodiments of this invention is produced from a polyester polyol
synthesized from dimer fatty acid, adipic acid, and 1,6-hexane
diol. The resulting polyester diol is reacted with isophorone
diisocyanate, dimethylol propionic acid and neopentyl glycol to
produce a polyurethane intermediate which is capped with
diethanolamine.
Pigments may be incorporated into the basecoat to provide the
desired cosmetic characteristics. This is done by mixing pigments
with the above-described pigment resin and optionally, with other
additives to form a pigment paste. Any standard pigment known in
the art may be used with resins of the present invention so long as
these pigments can be formulated without affecting the desired low
flash and quick-drying characteristics. Specific examples of the
dye stuffs or pigments may be inorganic or organic, for example,
graphite, carbon black, zinc chromate, strontium chromate, barium
chromate, lead chromate, lead cyanide, titanium dioxide, zinc
oxide, cadmium sulfide, iron oxide, aluminum flakes mica flakes,
zinc sulfide, phthalo cyanine complexes, naphthol red,
quinacridones and halogenated thioindigo pigments, among
others.
The preferred metallic pigments are metal powders preferably mixed
with aluminum metal flakes. Preferred aluminum flake pigments are
available from Silberline Corp, Lansford, Pennsylvania or from
Eckart Werke, Guenterstahl, West Germany. The aluminum flake
pigments provide the coating with an enhanced "metallic veneer". In
a preferred embodiment of the present invention standard grade
aluminum stabilized with phosphate ester is used. Other metallic
flake pigments, for example, silver may also be used but these are
usually prohibitive in cost and inferior in appearance. The
metallic pigments may also be mixed with non-metallic pigments, but
these are to be carefully chosen so as not to diminish the desired
metallic effect.
The resins used in the basecoat are dispersed in deionized water.
It is preferred that the deionized water have conductance readings
of less than 13 microohms.sup.-1 and most preferably less than
about 5 microohms.sup.-1 to prevent gassing caused by the reaction
of aluminum with water. Deionized water is also chosen to avoid
salts that naturally occur in tap water. Other solvents may also be
employed with the deionized water. An especially preferred solvent
is Butyl Cellosolve .TM. which aids mixing, formulating and
dispersing pigment in the basecoat composition. Other solvents can
also be used, for example, low-boiling mono and polyhydric
alcohols, ethers, esters, ketones and other organics. The organic
solvent, which comprises at most about 80% of the basecoat
composition, and preferably comprises about 10% to 20% by weight of
the basecoat composition (including water) may be selected to
promote the dispersibility of individual components in the final
basecoat composition (plasticizer characteristics) and for its low
volatitity characteristics.
A rheology control agent is also preferably incorporated into the
basecoat composition. The rheology control agent controls the
viscosity of the resulting composition and is incorporated in
amounts that will prevent sagging or running after a basecoat is
sprayed onto a vertical surface such as an automobile body. The
direct result of incorporating a rheology control agent is to
provide flow control, body and sprayability. Other favorable
results of adding a rheology control agent are to enhance the flip
effect of metallic flake pigments, to deposit a thicker coating,
and to achieve complete coverage of a substrate. The sprayed
coatings containing these agents also exhibit greater orientation
of the metallic flake pigments on the final coated substrate.
Rheology control agents which can be used in embodiments of the
present invention include the fumed silica compounds and the
bentonite clays. Preferred fumed silica compounds are the
hydrophobic silica compounds, for example Aerosil R972, available
from DeGussa Corporation, (Frankfurt, West Germany). Another
rheology control agent which may be used, and in certain basecoat
compositions, may be preferred is a synthetic sodium lithium
magnesium silicate hectorite clay. An example of one such clay is
Laponite RD, available from Laporte, Inc (Saddlebrook, N.J.). In
certain preferred embodiments rheology control agents are mixed.
The rheology control agent when it is included, generally comprises
about 0.1 to about 20 percent by weight of the basecoat composition
and preferably comprises between about 1 percent and about 5
percent by weight of the final basecoat composition.
In general, the particle size of the rheology control agent plays a
role in the overall thixotropic properties of these resins.
Rheology control agents in embodiments of this invention are
suspended in the material. It may be proposed that the rheology
control agents are suspended and function, at least in part,
through coulombic or electrostatic interactions.
In general, the particle sizes can be from less than 0.1 microns to
over about 200 microns. These sizes can be adapted to develop in
part the rheology properties sought. In appropriate circumstances,
the particle sizes may be from about 0.01 to about 10 microns.
In addition to a principal resin or major vehicle resin and a grind
resin, peferred basecoat compositions also are comprised of at
least about 5% by weight of the resinous vehicle of a
branched-chain polyester resin. The branched-chain polyester is
added for improved application properties and improved physical
properties (due to increased cross-link density). In general, the
branched-chain polyester is produced from the same components as
the polyester component except that in addition to the long and
short chain carboxylic acid components, a small percentage of
trifunctional acid or acid anhydride is used. Thus, the carboxylic
acid component of the branch-chain polyester is comprised of at
least 50% by weight of a long-chain fatty acid, preferably C36
dimer fatty acid and no more than about 50% by weight of a
combination of a dicarboxylic acid such as isophthalic acid and a
small percentage of a trifunctional carboxylic acid such as
trimellitic anhydride. In preferred embodiments, the branched chain
polyester is synthesized from dimer fatty acid, isophthalic acid,
and 1,6-hexane diol. A small percentage, about 5 to about 20% of
trimellitic anhydride is added to the polyesterification reaction
to branch the polyester. The branched chain polyester is cooked to
a final acid number of 10-50, and preferably, 20-40. In general,
the branched polyester comprises about 20% of the resinous vehicle,
but may be lower depending on the color.
Any additional agent used, for example, surfactants, fillers,
stabilizers, wetting agents, dispersing agents, adhesion promoters,
etc. may be incorporated into the basecoat composition. While the
agents are well-known in the prior art, the amount used must be
carefully controlled to avoid adversely affecting the coating and
quick-drying characteristics.
In formulating the basecoat compositions of the present invention,
the order of addition of the individual components is often very
important. As a rule, the cross-linking agent in a solvent is added
to the rheology control agent in solution and thoroughly mixed.
Thereafter, the major vehicle resin dispersion (neutralized with
amine) is added to the rheology control solution under agitation.
If desired, a slurry of aluminum metal flakes and/or mica particles
(mica particles are used alone in the case where an aluminum
metallic veneer is not desired) in Butyl Cellosolve .TM. is mixed
with a premixed slurry of a branched-chain polyester resin and
dimethylethanolamine. This mixture of aluminum is then agitated
with the slurry containing resinous vehicle, cross-linking agent,
and rheology control agent. Pigment pastes comprised of
polyurethane resin, pigment, fillers, stabilizers, plasticizers and
other additives are then mixed under agitation with the
above-resulting mixture. Pigment paste particles are prepared in a
sand mill, attritor or other common milling equipment prior to
use.
The pigment pastes may be prepared by mixing the aminoplast resin
with about 1/4 of the total polyurethane resin to be added to the
pigment paste. Pigment is added to this slurry under agitation for
about 1/2 hour. The rest of the polyurethane resin is then added
and the resulting paste is mixed for another half-hour. The pH and
viscosity of the paste is checked and any adjustments are made by
adding deionized water and/or tertiary amine. The weight ratio of
pigment to binder usually ranges between 0.15-5.0. The amount of
pigment ranges between 6 and 60% of the total weight of pigment
plus binder. Other well-known methods of formulating prepared
pigment pastes may also be used.
The final basecoat composition is adjusted to a pH of 7.6-7.8 with
a tertiary amine, for example, N-ethylmorpholine. Viscosity may be
adjusted using deionized water. Final basecoat compositions are
comprised of the following components in the indicated weight
ratios.
TABLE I ______________________________________ Amount (% by weight
of Solids of Final Basecoat Ingredient composition)
______________________________________ Polyurethane resin 20-80%
Melamine 5-50% Rheology Control Agent 0-20% Branched chain Polymer
0-35% Pigment 2-65% ______________________________________
The basecoat compositions described hereinabove can be applied to a
metal or plastic substrate in one or two coats using for example an
air atomizer (Binks Model 60 spray gun, available from Binks
Manufacturing Corporation, (Franklin Park, Ill.), or by using other
conventional spraying means. The basecoat compositions may also be
applied electrostatically. The basecoat compositions are preferably
sprayed at 50-80 psi, and a relative humidity of between 50 and 90%
(optimally at 60-80% relative humidity) and a temperature of
70.degree.-90.degree. F.
After being deposited, the basecoat compositions are flash dried
within a temperature range of about room temperature to about 145
degrees F. for between 30 second and about 10 minutes using warm
air blowing at a relative humidity of 5-40%. The preferred flash
temperature is about 120 degrees F. which is carried out for
preferably between about 1 and 5 minutes. The flash conditions
described herein result in about 90-95% of the solvents (water plus
organics) being flashed from the basecoat in this short period of
time.
After the first basecoat is deposited, a second basecoat can be
deposited over the first without drying (flash off), or
alternatively, a clearcoat may be deposited over the flashed
basecoat. Any number of clearcoat compositions known in the art may
be used. Any known unpigmented or other transparently pigmented
coating agent is in principle, suitable for use as a clearcoat. A
typical top coat composition contains 30-70% film forming resin and
30-70% volatile organic solvent.
After the clear coat is coated onto the basecoat layer, the
multi-layer coating is then baked to cross-link the polymeric
vehicle and to drive the small amount of residual water and organic
solvent from the multi-layered polymeric composition. A preferred
baking step involves heating the coated substrate for a period of
10-60 minutes at a temperature of between 150 and 300 degrees F.
The baking step cures the coating to a hard, durable film.
The invention will be further described in connection with several
examples which follow. These examples are shown by way of
illustration of the invention and are not meant to limit the scope
of the invention. All parts and percentages in the examples are by
weight unless otherwise indicated.
POLYURETHANE EXAMPLE 1
Preparation of a Polyurethane Resin
A polyester polyol resin is prepared by charging a reaction vessel
(flask with a fractionating column) with 551.9 g. (15.8% of the
polyester resin) of isophthalic acid, 1923 g. (54.9%) Empol 1010
(dimer fatty acid available from Emery Chemical Co.), and 1025.1 g.
(29.3%) of 1,6-hexanediol and 100 g. of toluene. Additional toluene
may be added to fill the trap. The mixture was heated under
nitrogen and the water of concondensation was removed. During this
heating 235.7 g. of water was distilled off. Heating was continued
at approximately 200 degrees C. until the acid number is less than
or equal to 8. The remaining toluene is then vacuum stripped at
220.degree. C. to produce a polyester resin for use in the
polyurethane resin.
At this point, 697.9 g. of the above-synthesized polyester resin
43.0 g. of dimethylol propionic acid, 16.1 g. of neopentylgylcol,
234.0 lbs. of Isophorone diisocyanate and 300 g. of methyl isobutyl
ketone are charged to a the reactor and heated at reflux (about 128
degrees C.) until a constant isocyanate value is obtained. 36.8 g.
of trimethylol propane is then added to the reactor and the batch
is allowed to reflux for an additional one hour. At this point, the
nitrogen purge is turned off and the batch is cooled to 95 degrees
C. 28.6 g. of dimethylethanolamine and 100 lbs of water is then
added using a portion of the water as a rinse. The batch is then
allowed to sit until it becomes homogeneous (about 5 minutes) and
then 2048.71 g. of water is added over a 20 minute period under
vigorous agitation.
At the end of this addition the mixture is distilled on high heat
with vigorous agitation to remove water and methyl isobutyl ketone.
The water is then returned to the batch and the approximately 300
grams of methyl isobutyl ketone which was distilled off is
discarded. 238 g. of n-butanol is added and the batch is held at 80
degrees C. for 30 minutes. The batch is then dropped and filtered
through a 10 micron filter to give a polyester-urethane vehicle for
use in the basecoat composition of the invention. The resulting
dispersion has a solids content of 30% and a Gardner viscosity of
Z2.
Polyurethane Dispersion 2
Preparation of Polyester Resin
A reaction vessel is charged with 1995 g. of adipic acid, 1995 g.
of dimer acid, and 2450 g. of 1,6-hexanediol, and 136 g. toluene.
The mixture is heated under nitrogen to 209 degrees C., removing
water until an acid number less than 8 is reached. Remaining
toluene is vacuum stripped to produce a polyester resin having
solids content greater than 98%.
Polyurethane Dispersion Preparation
857.4 g. of the above polyester is mixed with 14.6 g. neopentyl
glycol, 53.1 g. dimethylolpropionic acid, 306.5 g. isophorone
diisocyanate, 97.1 g. methyl ethyl ketone, and 235.0 g. methyl amyl
ketone are refluxed until a constant isocyanate value is obtained.
At this point, 24.8 g. of diethanolamine is added and the mixture
is held for 30 minutes. 24.8 g. of dimethylethanolamine and 116.8
g. deionized water and 118.2 g. isopropyl alcohol are added and
allowed to mix for 15 minutes. 3123.2 g. deionized water is then
added over a 20 minute period with vigorous agitation. The
resulting dispersion has a solids content of 26% and an appropriate
Gardner viscosity.
Polyurethane Dispersion 3
Preparation of Polyester
770 g. dimer acid, 230 g. 1,6-hexanediol, and 25 g. toluene are
charged and the resulting mixture heated to 200 degrees C. Heating
is continued, removing water, until an acid number less than 10 is
achieved. The remaining toluene is then removed under vacuum.
Polyurethane
700 g. polyester above, 12.6 g. neopentyl glycol, 43 g.
dimethylolpropionic acid, 244 g. isophorone diisocyanate, 77.8 g.
methyl ethyl ketone, and 195.3 methyl amyl ketone are reacted using
the procedure for polyurethane dispersion 2. The resulting
dispersion has a solids content of 26% and a Gardner viscosity of
Z1.
Branched Polyester 1
2594 g. of dimer acid, 2564 g. of 1,6-hexanediol, and 744 g. of
isophthalic acid are charged and the mixture heated to 195 degrees
C. under nitrogen with agitation until acid number of 10 or less is
reached. The mixture is then cooled to 150 degrees C. and 1000 g.
of trimellitic anhydride is added slowly, and refluxed until an
acid number of 30-32 is reached. After cooling to 150 degrees C. or
less, 729 g. of butyl Cellosolve .TM. and 1459 g. of n-butanol are
added. The resulting polyester has a solids content of 70% and a
Gardner viscosity of U-V.
Branched Polyester 2
1230 g. dimer acid and 769.5 g. 1,6 hexanediol, are charged and
heated to 195 degrees C. under nitrogen with agitation. Heating is
continued until an acid number less than 10 is reached. The mixture
is then cooled to 150 degrees C. and 420.1 g. trimellitic anhydride
is added slowly and heated until the acid number falls below 30.
335 g. butyl glycol and 670 g. n-butanol are then added with
agitation. The resulting polyester solution has a solids content of
70% and a Gardner viscosity of Z1.
Branched Polyester 3
868.7 g 1,6-hexanediol, 1346.2 g. dimer acid, and 386 g.
isophthalic acid are heated at 195 degrees C. until an acid number
less than 8 is achieved. 206.6 g. trimellitic anhydride is then
added slowly under agitation and heat applied until an acid number
less than 30 is achieved. A 2:1 mixture of n-butanol and butyl
glycol are then added, until 70% solids is reached. The resulting
branched polyester resin had a Gardner viscosity of U.
PREPARATION OF COATING AGENTS
The composition of the coating agents is shown in Table 2, where
the numbers denote parts by weight. The following notes refer to
components listed there: Thickener 1: Paste of Aerosil R972
(Degussa) hydrophobic fumed silica sand milled with appropriate
polyurethane grind resin and melamine in water, organic solvent
mixture at 11% strength.
Thickener 2: Paste of synthetic sodium lithium magnesium silicate
hectorite clay, Laponite RD (Laporte), 2% strength is deionized
water; the paste is prepared by stirring with Cowles blade in water
for one hour.
Thickener 3: Paste of Laponite RD 3% strength in deionized water.
Prepare as Thickener 2.
Titanium Dioxide Pigment Paste: 41% concentration of DuPont R-960
titanium dioxide sandmilled with appropriate polyurethane grind
resin and melamine.
Melamine Resin: Commercially available methanoletherfied
melamine/formaldehyde resin, solids content 90% by weight in
n-butanol.
Aluminum Pigment I: Silberline SS-5251 AR post treated with 4.5%
Vircopet 40 (phosphate ester commercially available from Albright
& Wilson, Richmond, Va.)
Aluminum Pigment II: Stapa Hydrolac WH-R607 from Eckart Werke
Aluminum Pigment III: Stapa Hydrolac WH-8487 from Eckwart Werke
______________________________________ 1 2 3 4 5 6 7 8 9
______________________________________ Thickener 2 40 37 37 38
Thickener 3 25 13 13 Melamine Resin 4 4 4 4 8 7 4 1 2 Butyl
Cellosolve 1 1 1 1 1 2 1 Polyurethane 1 40 40 18 (30% NV)
Polyurethane 2 44 42 38 17 (26% NV) Polyurethane 3 44 38 (26% NV)
Aluminum I (54% NV) 6 6 6 Aluminum II (65% NV) 5 Aluminum III (65%
NV) 5 6 Butyl Cellosolve 1 1 1 4 2 1 Polyester 1 (70%) 6 6 3
Polyester 2 (70%) 6 6 Polyester 3 (70%) 6 Dimethylethanolamine 2 2
2 2 1 6 6 1 5% Strength in Water Thickener 1 27 27 17 17 Titanium
Dioxide Paste 48 49 Deionized Water 12 4 12 12
______________________________________
EXAMPLES 1 TO 4
The melamine resin and Butyl Cellosolve are premixed and added to
the thickener under agitation. The polyurethane dispersion is then
added to this mixture under agitation. An aluminum slurry is made
by first mixing the aluminum pigment and butyl cellosolve then
adding the polyester resin, and then finally preneutralizing this
slurry with the 5% DMEA solution. The aluminum slurry is then added
to the polyurethane/thickener/melamine mixture under agitation.
EXAMPLE 5
Half of the melamine resin and butyl Cellosolve .TM. are premixed
and added to the thickener under agitation. The polyurethane
dispersion is then added. An aluminum slurry is made separately by
mixing the aluminum pigment, remaining butyl Cellosolve .TM. and
melamine resin. The aluminum slurry is then added under agitation
to the rest of the paint. The pH is then adjusted with 5%
dimethylethanolamine in water.
EXAMPLE 6
An aluminum slurry is made with aluminum pigment, melamine resin,
and Butyl Cellosolve under agitation. The polyurethane dispersion
is added to the aluminum slurry. Thickener is then added under
agitation. pH is adjusted with 5% DMEA and viscosity is adjusted
with deionized water.
EXAMPLE 7
The polyurethane dispersion, melamine resin, and Butyl Cellosolve
are mixed with agitation. An aluminum slurry is made as in Example
1 to 5 and added to the first mixture under agitation. The
thickener is added under agitation. Viscosity is adjusted with
deionized water.
EXAMPLES 8 AND 9
Melamine resin and Butyl Cellosolve are premixed and added under
agitation to Thickener 3. The polyurethane dispersion is then added
under agitation. In Example 8, the polyester resin is
preneutralized with 5% DMEA and then added under agitation.
Thickener 1 (R972 paste) is added and then the titanium dioxide
paste is added both under agitation.
The invention has been described in detail with particular
reference to preferred embodiments thereof, but it will be
understood that variations and modifications can be affected within
the spirit and scope of the invention and that the scope of the
invention is to be determined by the claims appended hereto.
* * * * *