U.S. patent application number 09/778921 was filed with the patent office on 2001-10-25 for silane-based, coating compositions, coated articles obtained therefrom and methods of using same.
Invention is credited to Schutt, John B..
Application Number | 20010032568 09/778921 |
Document ID | / |
Family ID | 27391962 |
Filed Date | 2001-10-25 |
United States Patent
Application |
20010032568 |
Kind Code |
A1 |
Schutt, John B. |
October 25, 2001 |
Silane-based, coating compositions, coated articles obtained
therefrom and methods of using same
Abstract
Silane based coating compositions provide durable, corrosion
resistant coatings on metal and non-metal surfaces. A typical
composition may include one or a mixture of silanes, such as
methyltrimethoxysilane and phenyltrimethoxysilane. The coating
compositions may be formulated with either acidic or basic
catalysts, the latter being especially suitable for coating steel
substrates. Coatings for food and beverage containers, automotive
finishes, HVAC surfaces, alkali metal silicates, concrete, and the
like, are described. Primer coating compositions which include two
or more polyfunctional organosilanes but no monofunctional
organosilanes provide strongly adherent corrosion resistant primer
coatings for metals and are very adherent to polyurethane, epoxy
and other resin topcoats.
Inventors: |
Schutt, John B.; (Silver
Spring, MD) |
Correspondence
Address: |
SHERMAN & SHALLOWAY
413 North Washington Street
Alexandria
VA
22314
US
|
Family ID: |
27391962 |
Appl. No.: |
09/778921 |
Filed: |
February 8, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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60185354 |
Feb 28, 2000 |
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60185367 |
Feb 28, 2000 |
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60236158 |
Sep 29, 2000 |
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Current U.S.
Class: |
106/287.11 ;
106/287.13; 106/287.14; 106/287.15 |
Current CPC
Class: |
C09D 4/00 20130101; C09D
183/14 20130101; C23C 2222/20 20130101; C09D 183/04 20130101; C09D
4/00 20130101; C08G 77/04 20130101; C09D 4/00 20130101; C08G 77/00
20130101; C09D 183/04 20130101; C08L 2666/54 20130101; C09D 183/14
20130101; C08L 2666/54 20130101 |
Class at
Publication: |
106/287.11 ;
106/287.13; 106/287.14; 106/287.15 |
International
Class: |
C09K 003/00 |
Claims
What is claimed is:
1. An aqueous coating composition formed by admixing (A) at least
one silane of the formula (1) R.sup.1Si(OR.sup.2).sub.3 (1) wherein
R.sup.1 is a lower alkyl group, a phenyl group or a functional
group containing at least one of vinyl, acrylic, amino, mercapto,
or vinyl chloride functional group; and R.sup.2 is a lower alkyl
group; (C) acid component comprising a member selected from the
group consisting of water-soluble organic acids, H.sub.3BO.sub.3
and H.sub.3PO.sub.3; and (D) water.
2. The aqueous coating composition according to claim 1, comprising
(B) at least one alkali component comprising an hydroxide or
carbonate of magnesium, calcium, zinc, or aluminum.
3. The aqueous coating composition according to claim 2, further
comprising (E) epoxide silane.
4. The aqueous coating composition according to claim 1, further
comprising (E) epoxide silane.
5. The aqueous coating composition according to claim 1, further
comprising a silane compound of formula (4):
X[R.sup.1Si(OR.sup.2).sub.3]- .sub.2 (4) where R.sup.1 and R.sup.2
are as defined above, and X represents an amino group (--NH) or
keto group 3
6. An aqueous coating composition formed by admixing (A) at least
one silane of the formula (1) R.sup.1Si(OR.sup.2).sub.3 (1) wherein
R.sup.1 is a lower alkyl group, a phenyl group or a functional
group including at least one of vinyl, acrylic, amino, mercapto, or
vinyl chloride functional group; and R.sup.2 is a lower alkyl
group; (B) base component; and (D) water.
7. An aqueous coating composition according to claim 6, further
comprising (E) epoxide silane.
8. An aqueous coating composition according to claim 6, wherein the
alkali component (B) comprises aminosilane.
9. An aqueous coating composition according to claim 8, further
comprising (E) epoxide silane.
10. An aqueous coating composition according to claim 8, wherein
the aminosilane comprises
3-(2-aminoethylamino)propyl-trimethoxysilane or
3-aminopropyltrimethoxysilane.
11. An aqueous coating composition according to claim 1, further
comprising (H) lower alkanol.
12. The coating composition according to claim 1, wherein in
formula (1) R.sup.2 is methyl.
13. The coating composition according to claim 1, wherein R.sup.1
is lower alkyl.
14. The coating composition according to claim 1, wherein said at
least one silane of formula (1) comprises
methyltrimethoxysilane.
15. The coating composition according to claim 1, wherein said at
least one silane comprises a mixture comprising
methyltrimethoxysilane and phenyltrimethoxysilane.
16. The coating composition according to claim 1, wherein said acid
component (C) comprises acetic acid.
17. The coating composition according to claim 1, wherein said acid
component comprises H.sub.3BO.sub.3.
18. The coating composition according to claim 1, wherein said acid
component comprises H.sub.3PO.sub.3.
19. The coating composition according to claim 1, further
comprising (F) silicate component selected from the group
consisting of ethyl orthosilicate and ethyl polysilicate.
20. The coating composition according to claim 19, wherein said
silicate component (F) has been hydrolyzed to about 28% to about
52% silica.
21. The coating composition according to claim 1, further
comprising (G) mono-lower alkyl ether of ethylene glycol.
22. The coating composition according to claim 1, further
comprising (I) ultra-violet light absorber.
23. The coating composition according to claim 1, further
comprising (J) (i) colloidal aluminum hydroxide, (ii) metal
alcoholate of the formula (2) M(OR.sup.3).sub.m (2) wherein M is a
metal of valence m, R.sup.3 is a lower alkyl group, m is an integer
of 3 or 4, or (iii) mixture of (i) and (ii).
24. The coating composition according to claim 23, comprising at
least one metal alcoholate of formula (2), wherein M is
titanium.
25. The coating composition according to claim 24, wherein R.sup.3
is an isopropyl group or an n-butyl group.
26. The coating composition according to claim 6, further
comprising (K) a gellation inhibiting amount of silane hydrolysis
catalyst.
27. The coating composition according to claim 26, wherein the
silane hydrolysis catalyst comprises chromium acetate
hydroxide.
28. The coating composition according to claim 26, wherein the
silane hydrolysis catalyst comprises acetic acid.
29. An aqueous coating composition formed by admixing (A) at least
one silane of the formula (1) R.sup.1Si(OR.sup.2).sub.3 (1) wherein
R.sup.1 is a lower alkyl group, a phenyl group or a bifunctional
silane containing vinyl, acrylic, amino, or vinyl chloride
functional group; and R.sup.2 is a lower alkyl group; (J) (i)
colloidal aluminum hydroxide, (ii) metal alcoholate of the formula
(2) M(OR.sup.3).sub.m (2) wherein M is a metal of valence m,
R.sup.3 is a lower alkyl group, misanintegerof3 or4, or (iii)
mixture of (i) and (ii); and (D) water.
30. The aqueous coating composition according to claim 29, further
comprising a gellation inhibiting effective amount of silane
hydrolyzing catalyst.
31. The aqueous coating composition according to claim 30, wherein
the silane hydrolyzing catalyst comprises epoxide silane.
32. An aqueous coating composition formed by admixing (A) at least
one silane of the formula (1) R.sup.1Si(OR.sup.2).sub.3 (1) wherein
R.sup.1 is a lower alkyl group, a phenyl group or a bifunctional
silane containing vinyl, acrylic, amino, or vinyl chloride
functional group; and R.sup.2 is a lower alkyl group; (D) water;
(H) lower alkanol; and (K) chromium acetate hydroxide.
33. An aqueous coating composition formed by admixing (A) at least
one silane of the formula (1) R.sup.1Si(OR.sup.2).sub.3 (1) wherein
R.sup.1 is a lower alkyl group, a phenyl group or a functional
group including at least one of vinyl, acrylic, amino, mercapto, or
vinyl chloride functional group; and R.sup.2 is a lower alkyl
group; (D) water; (F) alkali metal silicate, which may be
hydrolyzed; (H) lower alkanol; and (J) (i) colloidal aluminum
hydroxide, (ii) metal alcoholate of the formula (2)
M(OR.sup.3).sub.m (2) wherein M is a metal of valence m, R.sup.3 is
a lower alkyl group, m is an integer of 3 or 4, or (iii) mixture of
(i) and (ii).
34. The aqueous coating composition according to claim 33, further
comprising (E) epoxide silane.
35. The composition according to claim 1, further comprising a
catalytic amount of calcium hydroxide or tetramethylammonium
hydroxide, and wherein component (A) comprises a mixture of at
least two silane compounds of formula (1), wherein R.sup.1 in one
silane compound is a lower alkyl group and R.sup.1 in another
silane compound is an aryl group.
36. The composition according to claim 35, wherein component (A)
comprises a mixture of methyltrimethoxysilane and
phenyltrimethoxysilane; and component (C) comprises partially
hydrolyzed tetraethylsilicate.
37. The composition according to claim 36, further comprising (G)
lower alcohol solvent.
38. A non-metallic aqueous coating composition formed by admixing
(A) at least one silane of the formula (1)
R.sup.1Si(OR.sup.2).sub.3 (1) wherein R.sup.1 is a lower alkyl
group, a phenyl group or a functional group including at least one
of vinyl, acrylic, amino, mercapto, or vinyl chloride functional
group; and R.sup.2 is a lower alkyl group; (A1)
3-(2-aminoethylamino)propyltrimethoxysilane or
3-aminopropyltrimethoxysil- ane; (D) water; (E) epoxide silane; and
(H) lower alkanol.
39. An aqueous coating composition formed by admixing (A) at least
one silane of the formula (1) R.sup.1Si(OR.sup.2).sub.3 (1) wherein
R.sup.1 is a lower alkyl group, a phenyl group or a functional
group including at least one of vinyl, acrylic, amino, mercapto, or
vinyl chloride functional group; and R.sup.2 is a lower alkyl
group; (B) at least one alkali component comprising an hydroxide or
carbonate of divalent metal; (C) boric acid; (D) water; (E) ethyl
polysiloxane; and (H) lower alkanol.
40. A hydrolyzable primer coating composition comprising a mixture
of two or more polyfunctional organosilane compounds in a volatile
organic solvent, said composition being free from monofunctional
silane compounds.
41. The primer coating composition according to claim 40, which
contains an aminoalkylaminoalkyltrialkoxysilane and an epoxy
silane.
42. A primer coating composition obtained by admixing the
hydrolyzable coating composition of claim 40 or claim 41, and
water.
43. A primed substrate comprising a substrate on which the primer
coating of claim 42 is applied and cured.
44. A composition effective for providing a corrosion resistant
composition in combination with water, comprising the product
obtained by admixing a. at least two silanes represented,
independently, by formula (1') R.sup.1Si(OR.sup.2).sub.3 (1')
wherein at least one R.sup.1' represents a lower alkyl group in at
least one silane of formula (1'), at least one R.sup.1' represents
a group containing a functional mercapto group, and any other
R.sup.1' groups may represent a phenyl group, or a functional group
including at least one of vinyl, acrylic, amino, or vinyl chloride
functional group; and R.sup.2 represents a lower alkyl group; and
(H) lower alkanol.
45. An aqueous coating composition comprising the composition of
claim 44 and water.
46. A composition which, in combination with water, forms a neutral
or basic composition effective to provide a corrosion resistant
coating, comprising the product obtained by admixing in a lower
alkanol solvent, at least two silanes, represented independently by
formula (1") R.sup.1"Si(OR.sup.1).sub.3 wherein at least one
R.sup.1" represents lower alkyl group; at least one R.sup.1"
represents a group containing a functional amino group; and any
other R.sup.1" group represents, phenyl, or a functional group
including at least one of vinyl, acrylic, or vinyl chloride
functional group; and R.sup.2 represents lower alkyl group.
47. An aqueous neutral or basic coating composition, comprising the
composition of claim 46, in admixture with water.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from Provisional
Applications Ser. No. 60/185,354 and Ser. No. 60/185,367, both
filed Feb. 28, 2000, and from Provisional Application No.
60/236,158, filed Sep. 29, 2000.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to compositions useful for
coating various surfaces, including, metals, especially aluminum,
steel and galvanized steel, and various metal alloys, such as
brass, alkali metal silicate coatings, priming metals, painted
finishes, marine finishes, and the like. More particularly, this
invention relates to silane-based, coating compositions which are
catalyzed with acid and/or base metallic and/or non-metallic
compounds and which form strongly adherent, corrosion resistant
coatings on a wide range of painted and non-painted surfaces,
including metals, plastics, concrete and alkali metal silicates.
Coating compositions of this invention provide hard, transparent,
durable coatings which do not suffer noticeable degradation in
gloss nor concurrent yellowing over long periods of time under
exposure to corrosive, e.g., acidic or alkaline conditions.
[0004] 2. Discussion of the Prior Art
[0005] It is well known to catalyze silanes with acids. However,
acid catalyzed aqueous silane coating compositions are not
considered useful for coating steel; the acid conditions, e.g., pH
below 7, promote corrosion of the steel substrate.
[0006] U.S. Pat. Nos. 3,944,702, 3,976,497, 3,986,997 and 4,027,073
describe coating compositions, which are acid dispersions of
colloidal silica and hydroxylated silsequioxane in an alcohol-water
medium.
[0007] U.S. Pat. No. 4,113,665 discloses chemically resistant
ambient curable coatings based on a binder of which the major
portion is prepared by reacting, in an acidic solution,
trialkoxysilanes (e.g., methyltriethoxysilane) with aliphatic
polyols, silicones or both. Barium fillers, such as barium
metaborate, may be added to provide resistance to sulfur dioxide.
Zinc oxide or metallic zinc may be included for further corrosion
resistance. The compositions may be applied to, e.g., steel
petroleum tanks, by spraying, concrete, vitreous surfaces.
[0008] U.S. Pat. No. 4,413,086 describes water reducible coating
compositions containing organosilane- polyol which is a reaction
product between certain hydrophilic organic polycarbinols and
organosilicon material, e.g., organosilane, curing agent (e.g.,
aminoplast resin), organic solvent (optional), essentially
unreacted polyol (optional), essentially unreacted hydrolyzed and
condensed organosilane (optional), water (optional) and pigment
(optional).
[0009] U.S. Pat. No. 4,648,904 describes an aqueous emulsion of (a)
hydrolyzable silane, inclusive of methyltrimethoxysilane, (b)
surfactant (e.g., Table I, col. 4) and (c) water. The coatings may
be used for rendering masonry water repellant.
[0010] U.S. Pat. No. 5,275,645 is purported to provide an
improvement to the acid-catalyzed organosilane coating compositions
of the above-mentioned U.S. Pat. No. 4,113,665. According to this
patent a protective coating is obtained at ambient temperature from
a coating composition containing organosilanes having an Si-O bond,
using an amine catalyst and an organometallic catalyst.
[0011] U.S. Pat. No. 5,879,437 describes a coating composition
containing a tetraalkyl silicate or monomeric or oligomeric
hydrolysis product thereof, present in a proportion of 40-90% by
weight based on the non-volatile content of the composition and a
hydrous oxide sol (Type A or Type B), in an amount such that the
oxide constitutes 10-60% by weight of the non-volatiles. According
to the patentees, this coating composition is suitable for the
pretreatment of solid surfaces such as metals generally, including
steel, titanium, copper, zinc and, particularly aluminum, to
improve adhesion properties of the pretreated surface to
subsequently applied coatings, such as paint, varnish, lacquer; or
of adhesive, either in the presence or absence of a lubricant.
[0012] U.S. Pat. No. 5,882,543 describes methods and compositions
for dehydrating, passivating and coating HVAC and refrigeration
systems. The compositions include an organometalloid and/or
organometallic compound, which reacts with water in the system. The
sealing function of these compositions is apparently obtained by
introducing the composition to the fluid enclosure and upon exiting
from an opening, the composition (i.e., organometallic) reacts with
atmospheric moisture to seal the opening.
[0013] U.S. Pat. No. 5,939,197 describes sol-gel coated metals,
especially titanium and aluminum alloys. The sol-gel coating
provides an interface for improving adhesion, through a hybrid
organometallic coupling agent at the metal surface, between the
metal and an organic matrix resin or adhesive. The sol is
preferably a dilute solution of a stabilized alkoxyzirconium
organometallic salt, such as tetra-i-propoxy-zirconium, and an
organosilane coupling agent, such as 3-glycidyloxypropyltrimethoxy-
silane, with an acetic acid catalyst.
[0014] U.S. Pat. No. 5,954,869 discloses an antimicrobial coating
from water-stabilized organosilanes obtained by mixing an
organosilane having one or more hydrolyzable groups, with a polyol
containing at least two hydroxyl groups. This patent includes a
broad disclosure of potential applications and end uses, e.g.,
column 4, lines 35-53; columns 23-25.
[0015] U.S. Pat. No. 5,959,014 relates to organosilane coatings
purported to have extended shelf life.
[0016] Organosilane of formula R.sub.nSiX.sub.4-n (n=0-3;
R=non-hydrolyzable group; X=hydrolyzable group) is reacted with a
polyol containing at least three hydroxyl groups, wherein at least
any two of the at least three hydroxyl groups are separated by at
least three intervening atoms.
[0017] U.S. Pat. No. 6,057,040 relates to novel bis-aminosilanes
and coating compositions containing the bis-aminosilanes.
[0018] In my recently issued U.S. Pat. No. 5,929,129, there are
described corrosion resistant coatings provided by
aqueous-alcoholic dispersions of the partial condensate of
monomethyl silanol (obtained by hydrolysis of monomethyl
alkoxysilane) alone or in admixture with minor amounts of other
silanol, e.g., gamma-glycidyloxy silanol, wherein the reaction is
catalyzed by divalent metal ions, e.g., Ca.sup.+2, typically from
alkaline earth metal oxides. When these coating are applied to,
e.g., boat hulls, such as aluminum hulls, they are highly effective
in preventing corrosion from salt water for extended periods.
[0019] The coating compositions of this earlier patent, have also
been found to be very highly effective in providing strongly
adherent, corrosion resistant coatings on a variety of other
substrates and products, including, especially, air conditioning
and other HVAC systems (see, e.g., Provisional Application No.
60/181061, filed Feb. 8, 2000, in the names of Anthony Gedeon, et
al.).
[0020] In my Provisional Application, Ser. No. 60/185,354, filed
Feb. 28, 2000, silane-based, aqueous coating compositions are
described which are especially adapted for coating or overcoating
refurbished painted finishes, especially as a gel-coat restorative
for fiberglass-reinforced epoxy and polyester resins, particularly,
for boat hulls and other marine finishes. According to this
Provisional application, an acidic aqueous silane based coating
composition is described which is obtained by admixing (A) at least
one silane of the formula (1)
R.sup.1Si(OR.sup.2).sub.3 (1)
[0021] wherein
[0022] R.sup.1 is a lower alkyl group, a phenyl group or an
N-(2-aminoethyl)-3-aminopropyl group, and
[0023] R.sup.2 is a lower alkyl group;
[0024] (B) acid component selected from water-soluble organic
acids, H.sub.3BO.sub.3 and H.sub.3PO.sub.3; and
[0025] (C) water.
[0026] Other ingredients which can be used in these compositions
include silicates, mono-lower alkyl ethers of ethylene glycol,
lower alkanol, ultraviolet light absorbers, colloidal aluminum
hydroxides and metal alcoholates.
[0027] In my provisional application Ser. No. 60/185,367, filed
Feb. 28, 2000, I described non-aqueous coating compositions
containing, for example, (A) silanes represented by formula
(1):
R.sup.1nSi(OR.sup.2).sub.4-n (I)
[0028] where R.sup.1 is a lower alkyl group, phenyl group,
3,3,3-trifluoropropyl group, .gamma.-glycidyloxypropyl,
.gamma.-methacryloxypropyl group, N-(2-aminoethyl)-3-aminopropyl
group or aminopropyl group,
[0029] R.sup.2 is a lower alkyl group; and
[0030] n is a number of 1 or 2;
[0031] (B) vinyltriacetoxysilane and/or colloidal aluminum
hydroxide and/or at least one metal alcoholate of formula (2):
M(OR.sup.3).sub.m (2)
[0032] where M is a metal of valence m, R.sup.3 is a lower alkyl
group; and n is a number of 2 to 4. In other embodiments, the
compositions may further include one or more of (C)
ethylortho-silicate, ethylpolysilicate or colloidal silica
dispersed in lower alkanol; (D) boric acid, optionally dissolved in
lower alkanol; (E) .gamma.-glycidyloxypropyltrime- thoxysilane; (F)
finely divided solid lubricant.
[0033] In addition to the immediately above described compositions,
which form part of the present invention, there is still a need to
provide corrosion resistant coatings which do not require acidic
pH's to catalyze the polymerization of silanols to form
polysiloxane coatings and which may be applied to steel or other
acid degradable surfaces.
[0034] There is also a need to provide coating compositions with
improved pot life, namely, slow polymerization rates.
[0035] There is also a need to provide silane based aqueous coating
compositions which are effective to overcoat silicate coatings.
[0036] It would also be advantageous to provide silane based
aqueous coating compositions which do not include or require
surfactants or emulsifiers.
[0037] More generally, there is still a need in the coating art for
coating compositions which are easy to apply to various metallic or
non-metallic substrates and which provide improvements in
durability, including adhesion to the substrate, corrosion
resistance to acids, alkalis and solvents, and other improved
properties, such as transparency, freedom from gellation, storage
stability, and the like.
[0038] The foregoing and other objects of this invention are
described in further detail below.
SUMMARY OF THE INVENTION
[0039] Accordingly, this invention provides compositions effective
for coating a wide range of metallic and/or non-metallic surfaces,
including steel, galvanized steel, brass, aluminum, alkali metal
silicates, glass, fiberglass, painted surfaces and the like.
[0040] In accordance with one embodiment hereof, an aqueous coating
composition is formed by admixing the following ingredients (A),
one or both of (B) and/or (C), and (D):
[0041] (A) at least one silane of the formula (1)
R.sup.1Si(OR.sup.2).sub.3 (1)
[0042] wherein
[0043] R.sup.1 is a lower alkyl group, a phenyl group or a
functional group, including at least one of vinyl, acrylic, amino,
mercapto, or vinyl chloride functional group; and
[0044] R.sup.2 is a lower alkyl group;
[0045] (B) base component;
[0046] (C) acid component selected from the group consisting of
alkanoic acid having from about 1 to about 5 carbon atoms,
H.sub.3BO.sub.3 and H.sub.3PO.sub.3; and
[0047] (D) water.
[0048] The composition may further comprise (E) epoxy silane.
Especially when component (C) is present, the composition may also
further comprise an hydroxide or carbonate of magnesium, calcium or
zinc. When component (B) is present, the base component may be
aminosilane, such as, for example,
3-(2-aminoethylarnino)propyltrimethoxysilane or
3-aminopropyltrimethoxysilane. The composition with components (B)
and/or (C) may further comprise one or more of, for example, (E)
epoxysilane; (F) alkali metal silicate component, which may be
hydrolyzed; (G) mono-lower alkyl ether of ethylene glycol; (H)
lower alkanol; (I) ultra-violet light absorber; (J) (i) colloidal
aluminum hydroxide or (J)(ii) metal alcholate of formula (2)
M(OR.sup.3).sub.m (2)
[0049] where M represents a metal of valence m, each R.sup.3
independently represents lower alkyl; and m is an integer of 3 or 4
or both (J)(i) and (J)(ii); (K) a color forming silane hydrolysis
catalyst, such as, for example, chromium acetate hydroxide.
[0050] In accordance with another embodiment of the invention,
there is provided an aqueous coating composition formed by admixing
(A) at least one silane of formula (1) given above; (D) water; (J)
(i) colloidal aluminum hydroxide or (ii) metal alcoholate of
formula (2) M(OR.sup.3).sub.m wherein M is a metal of valence m,
R.sup.3 is a lower alkyl group, and m is 3 or 4, or (iii) a mixture
of (i) and (ii); and, optionally, a silane hydrolyzing catalyst,
effective to inhibit gellation and extend storage life and pot
life, such as epoxide silane.
[0051] In accordance with still yet another embodiment of the
invention, there is provided an aqueous coating composition formed
by admixing (A) at least one silane of formula (1) given above; (H)
lower alkanol solvent; (D) water; (K) chromium acetate hydroxide or
other silane polymerization catalyst which provides coloration to
the resulting coating.
[0052] Another embodiment provided by the present invention is an
aqueous coating composition formed by admixing (A) at least one
silane of formula (1) given above; (D) water; (F) alkali metal
silicate, optionally pre-hydrolyzed; (H) lower alkanol as solvent;
and (J) (i) colloidal aluminum hydroxide or (ii) metal alcoholate
of formula (2) given above or (iii) a mixture of (i) and (ii).
[0053] In another embodiment of the invention there is provided a
non-metallic aqueous coating composition formed by admixing (A) at
least one silane of formula (1) given above; (B) a basic amine
silane catalyst, such as 3-(2-aminoethylamino)propyltrimethoxy
silane or 3-aminopropyltrimethoxy silane; (D) water; (E) epoxide
silane; (H) lower alkanol solvent.
[0054] The present invention further provides an aqueous coating
composition containing mixed valence silane catalysts. According to
this embodiment of the invention, an aqueous coating composition is
formed by admixing (A) at least one silane of formula (1) given
above; (B) at least one compound comprising an hydroxide or
carbonate of a divalent metal, such as calcium or magnesium; (C)
boric acid or phosphorous acid; (D) water; (E) ethyl polysiloxane;
(H) lower alkanol solvent, and (J) a metal alcoholate of formula
(2) above, wherein M represents a tetravalent metal, i.e., m=4,
such as, for example, tetrabutoxytitanate.
[0055] In still yet another aspect of the invention there is
provide an aqueous alcoholic coating composition effective for
providing clear, hard and strongly adherent corrosion resistant
coatings for glass substrates and for providing clear, hard, glossy
and slick (slippery or wax-like) adherent corrosion resistant
coatings for metal substrates, such as automobiles and other
vehicles. According to this aspect of the invention, there is
provided a coating composition which is an alcoholic solution
containing as the essential and major film-forming components a
mixture of silane compounds of the above formula (1) wherein the
R.sup.1 group in one silane compound is the lower alkyl group and
in another silane compound the R.sup.1 group is an aryl group,
especially, a phenyl group. The composition also includes small
amounts of an alcohol soluble activator, such as,
tetramethylammonium hydroxide or calcium hydroxide, which
functions, on glass, as an abrasive agent and etchant, and a
silicate, preferably, partially hydrolyzed silicate, especially a
hydrolysis product of tetraethylsilicate. The non-aqueous
compositions may additionally include as an optional but preferred
ingredient, .gamma.-glycidyloxypropyltrimethoxysilane or other
epoxysilane compound.
[0056] According to the present invention, the non-aqueous
composition as described in the previous paragraph may be applied
to a substrate, such as glass window (particularly, the outside
surface of the glass window), or to the painted finish of an
automobile, by wiping with a brush, sponge, or soft cloth. After
allowing the alcohol to evaporate, leaving a whitish or chalky
finish, due to the Ca(OH).sub.2 particles deposited on the surface,
the coating is polished to provide a highly transparent hard
adherent finish. When applied to a painted metal surface, such as
an automobile, the coating becomes slick and glossy, providing a
highly durable finish, much superior to known wax finishes. For
optimum results, it may be and generally is necessary to thoroughly
pre-clean the surface to be coated.
[0057] The invention also provides the novel coatings obtained from
any of the above aqueous coating compositions and the coated
articles obtained there from.
[0058] In still another aspect of the invention, there is provided
a coating composition which is highly effective as a primer for
steel, galvanized steel, aluminum and other metal surfaces.
According to this aspect of the invention the primer coating
composition contains as the essential ingredients at least two
polyfunctional organosilane compounds, such as, an
aminoalkylaminoalkyltrialkoxysilane and an epoxy silane in a
volatile organic solvent, especially lower alkanol solvent. The
alcohol or other organic solvent mixture of the polyfunctional
silane compounds is combined with a small quantity of water, as
silane hydrolyzing catalyst. These primer coating compositions are
free from silica and are also free from monofunctional silanes.
[0059] The present invention, including specific applications
thereof, will now be described in further detail by way of specific
embodiments and examples, although the invention is not limited to
these specific embodiments.
DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS
[0060] According to one embodiment of this invention, a coating
composition is formed by admixing
[0061] (A) at least one silane of the formula (1)
R.sup.1Si(OR.sup.2).sub.3 (1)
[0062] wherein
[0063] R.sup.1 is alkyl, preferably, a C.sub.1-C.sub.6 alkyl group
(the group may be a straight, cyclic, or branched-chain alkyl),
such as methyl, ethyl, n- or iso-propyl, n- or iso-butyl, n-pentyl,
cyclohexyl, and the like, preferably a C.sub.1-C.sub.4 alkyl group,
most preferably a methyl, ethyl, propyl or butyl group), aryl, such
as a phenyl, or a functional group or groups, such as vinyl,
acrylic, methacrylic, amino, mercapto, or vinyl chloride functional
group, and each R.sup.2 is, independently, an alkyl group (i.e. a
C.sub.1-C.sub.6 straight or branched chain alkyl group, preferably
a C.sub.1-C.sub.4 alkyl group, such as a methyl group);
[0064] (B) base component selected from calcium, zinc and aluminum
hydroxides;
[0065] (C) acid component selected from the group consisting of
water-soluble organic acids (preferably alkanoic acid such as
formic acid, acetic acid, propanoic acid or butyric acid, most
preferably acetic acid), H.sub.3BO.sub.3 (boric acid) and
H.sub.3PO.sub.3 (phosphorous acid); and
[0066] (D) water.
[0067] As examples of silanes of formula (1), wherein R.sup.1 is an
alkyl group or aryl group, mention may be made of, for example,
methyltrimethoxysilane, ethyltrimethoxysilane,
ethyltriethoxysilane, n-propyltrimethoxysilane,
n-propyltriethoxysilane, isopropyltrimethoxy silane,
n-butyltrimethoxy silane, isobutyltrimethoxy silane,
phenyltrimethoxy silane, preferably methyltrimethoxy silane. In the
case where R.sup.1 is a functional group, mention may be made, for
example, of N-(2-aminoethyl)-3-aminopropyltrimethoxy silane,
3-mercaptopropyltrimetho- xy silane, 3-mercaptopropyltriethoxy
silane, 3-aminopropyltriethoxy silane, 3-(meth)acryloxypropyl
trimethoxy silane, 3-(meth)acryloxypropylt- riethoxy silane,
n-phenylaminopropyltrimethoxy silane, vinyltriethyoxy silane,
vinyltrimethoxy silane, allyltrimethoxy silane, and any of the
aminosilane catalysts, described herein below as component
(B.sup.1).
[0068] As used herein, the expression "functional group" is
intended to include any group, other than hydroxyl, (including
alkoxy, aryloxy, etc.), which is hydrolyzable to provide, in situ,
a reactive group (e.g., reactive hydrogen) which will react, in
other than a condensation reaction, with the substrate (e.g.,
metal), itself, or other reactive components in or from the coating
composition.
[0069] The functional groups, in addition to the hydroxyl group (by
hydrolysis of the (OR.sup.2) groups), tend to form
three-dimensional or cross-linked structure, as well known in the
art.
[0070] Moreover, in the various embodiments of the invention, it is
often preferred to use mixtures of two or more silane compounds of
formula (1). Mixtures of at least phenyltrimethoxysilane and
methyltrimethoxysilane are often especially preferred.
[0071] Generally, total amounts of silane compounds of formula (1)
will fall within the range of from about 40 to about 90 percent by
weight, preferably from about 50 to about 85 percent by weight,
based on the total weight of silanes, acid component and water.
[0072] In addition to silane compound(s) of formula (1), the
composition may additionally include a bistrifunctional
aminosilane, such as represented by the following formula (4):
X[R.sup.1Si(OR.sup.2).sub.3].sub.2 (4)
[0073] where R.sup.1 and R.sup.2 are as defined above, and X
represents an amino group (--NH) or keto group 1
[0074] as a basic catalyst, not requiring acid stabilization. As a
representative example of aminosilane or ketosilane catalyst
according to formula (4), mention may be made of, for example,
bis(trimethoxypropylsil- ane) amine, bis(trimethoxyethylsilane)
amine, di(trimethoxybutylsilane) ketone, di(trimethoxypropylsilane)
ketone, and the like. The silane compounds of formula (4) function
as a less active basic catalyst, not requiring acidic passivation.
Minor amounts, usually from about 1 to about 10 parts, preferably,
from about 2 to about 8 parts, of compound of formula (4) per 100
parts of silane compound(s) of formula (1) provide satisfactory
results.
[0075] The base component (B) may be, for example, an inorganic
base, such as, for example, calcium hydroxide, aluminum hydroxide
or zinc hydroxide, or mixture thereof, or an organic base
component, such as, for example, aminosilane.
[0076] The amount of the base component is generally, up to about
2%, such as, for example, from about 0.1 to 2.0%, by weight of the
composition, especially, from about 0.2 to 1.6%.
[0077] As examples of the acid component (C), mention may be made
of lower alkanoic acids, such as, for example, formic acid, acetic
acid, propanoic acid, butyric acid, and inorganic acids, such as,
for example, boric acid (H.sub.3BO.sub.3) or ortho-phosphorous acid
(H.sub.3PO.sub.3), preferably acetic acid, boric acid or
ortho-phosphorous acid, most preferably, for reasons of economy and
safety, acetic acid. The acid may be added as free acid or as
inorganic salt thereof, such as alkali metal (e.g., sodium),
alkaline earth metal (e.g., calcium), or ammonium salt.
[0078] Generally, total amounts of the inorganic acid component
will fall within the range of from about 0.3 to about 4 percent by
weight, preferably from about 0.5 to about 3%, preferably, from
about 0.5 to about 2.5 percent by weight, based on the total weight
of silanes, acid component and water. For acetic acid, the
preferred range is from about 0.1 to about 1.0 percent, preferably,
from about 0.2 to about 0.7 percent, by weight, based on the total
weight of the composition.
[0079] Generally, the total amount of water will fall within the
range of from about 10 to about 60 percent by weight, preferably
from about 10 to about 45 percent by weight, based on the total
weight of silanes, acid component and water.
[0080] Some or all of the water may be provided by the acid
component, when the base or acid component is supplied as an
aqueous solution, e.g., 5% aqueous solution of ortho-phosphorous
acid or saturated aqueous solution of boric acid (about 6% by
weight of H.sub.3BO.sub.3).
[0081] Since the presence of metallic and other impurities may have
an adverse effect on the properties of the resulting coatings,
preferably, the water is distilled or de-ionized water.
[0082] While general and preferred ranges of amount for the
film-forming and catalytic components have been described above, it
will be recognized by those skilled in the art, that these amounts
may be increased or decreased as necessity demands and that the
optimum amounts for any particular end use application may be
determined by the desired performance. In this regard, for example,
when the amount of catalyst is reduced, the time to achieve freedom
from tack will increase. Similarly, when the amount of the
catalyst(s) is (are) increased, this may lead to increased rates of
cracking, loss of adhesion and performance loss of the resulting
coating.
[0083] The compositions of this embodiment may further include one
or more additional additives for functional and/or esthetics
effects, such as, for example, silicates, organic solvents and
co-solvents, UV absorbers, metal catalysts and the like.
[0084] The above-noted optional ingredients may be used singly or
in any combination in the coating composition of this
invention.
[0085] As examples of silicate component, mention may be made of
ethyl or methyl orthosilicate or ethyl polysilicate. These
silicates may be hydrolyzed, for example, from about 28% to about
52% silica. Especially preferred in this regard is
tetraethylsilicate (TEOS) which has been subjected to controlled
hydrolysis, providing a mixture of TEOS and, from about 20% to
about 60% polydiethoxysilane oligomers. For example, a 50%
hydrolysis product may be referred to herein as "polydiethoxysilane
(50%)."
[0086] Generally, total amounts of silicate component, when used,
will fall within the range of from 0 to about 45 percent by weight,
preferably from 0 to about 25 percent by weight, based on the total
weight of silanes, acid component and water.
[0087] As examples of mono-lower alkyl ether of alkylene (e.g.,
ethylene) glycol, mention may be made of mono-C.sub.1-C.sub.6-alkyl
ethers of ethylene glycol, such as, for example, monomethyl ether,
monoethyl ether, monopropyl ether, monobutylether, monopentylether
or monohexylether, preferably monoethyl ether of ethylene
glycol.
[0088] Generally, total amounts of the mono-lower alkyl ether of
ethylene glycol, when used, will fall within the range of from 0 to
about 15 percent by weight, preferably from 0 to about 6 percent by
weight, based on the total weight of silanes, acid component and
water. As an example of ultra-violet light absorber, mention may be
made of titanium dioxide in finely powdered form, e.g., having an
average particle diameter of about 20 nm. Other inorganic or
organic ultra-violet light absorbers may be utilized in so far as
they do not interfere with the objects of this invention.
[0089] Generally, total amounts of the ultra-violet light absorber,
when used, will fall within the range of from 0 to about 10 percent
by weight, preferably from 0 to about 5 percent by weight, based on
the total weight of silanes, acid component and water. As examples
of organic solvents, mention may be made of lower alkanol, e.g.,
C.sub.2-C.sub.4 alkanols, preferably isopropanol. Other organic
solvents, such as, for example, acetone, methyl ethyl ketone, ethyl
acetate, and the like may also be used.
[0090] Generally, total amounts of organic solvent, such as, lower
alkanol, will fall within a range of from 0 to about 50 percent by
weight, preferably from 0 to about 30 percent by weight, based on
the total weight of silane(s), acid component and/or base component
and water. In some cases, however, substantially higher amounts may
be convenient, especially where, for example, the coating
compositions are applied by spraying as an aerosol or mist.
[0091] As examples of the metal catalysts, mention may be made of
(i) colloidal aluminum hydroxide, (ii) metal alcoholates, such as
those represented by the following formula (2):
M(OR.sup.3).sub.m (2)
[0092] where M is a metal of valence m (namely, from Groups IIIA,
IVA, IIB or IVB of the periodic table of the elements), e.g.,
boron, titanium, aluminum, indium, yttrium, cerium, lanthanum,
silicon, tin, hafnium, etc; boron, aluminum and titanium are
especially preferred because the alkoxides of these metals are more
readily commercially available, and tend to be non-toxic);
[0093] R.sup.3 is a lower alkyl group, e.g., C.sub.1-C.sub.6
straight or branched chain alkyl group, preferably C.sub.2-C.sub.4
alkyl group, most preferably, isopropyl, isobutyl or n-butyl;
and
[0094] m is an integer of 3 or 4.
[0095] As specific examples of the metal alcoholates of formula
(2), mention may be made of titanium alcoholates of C.sub.2-C.sub.4
alkanols, e.g., titanium tetraisopropoxide and titanium
tetrabutoxide.
[0096] In addition, double metal alcoholates of, for example, AlTi,
AlZr, AIY, MgAl, MgTi, MgZr, etc., may also be used.
[0097] The presence of the trivalent and tetravalent metal ions are
especially useful for coating compositions applied to steel since
they tend to form insoluble (water and alkali) iron silicates,
whereas the products of divalent metals, tend to be soluble.
[0098] Generally, total amounts of the colloidal aluminum hydroxide
and/or metal alcoholate, when used, will fall within the range of
from 0 to about 2.5 percent by weight, preferably from 0 to about 1
percent by weight, based on the total weight of silanes, acid
component and water.
[0099] Within the above general proportions, the silane component
(A) may be used in an amount of from about 15 to about 25 parts by
weight, preferably as a mixture of from about 15 to about 20 parts
by weight of methyltrimethoxysilane and from about 1 to about 5
parts by weight of phenyltrimethoxysilane; the base component (B),
when present, is used in an amount of from about 0.1 to 3 weight
percent, preferably from about 0.2 to 2.5 weight percent; the acid
component (C), when present, is used in an amount of from about 0.2
to about 0.8 part by weight; the water (D) is used in an amount of
from about 2.5 parts by weight to about 22 parts by weight; the
silicate component is used in an amount of from 0 to about 15 parts
by weight; the mono-lower alkyl ether of ethylene glycol is used in
an amount of from 0 to about 3 parts by weight; the ultra-violet
light absorber is used in an amount of from 0 to about 2 parts by
weight; and lower alkanol is used in an amount of from 0 to about
20 parts by weight; and the colloidal aluminum hydroxide and/or the
metal alcoholate is used in an amount of from 0 to about 0.5 part
by weight.
[0100] According to a particularly preferred embodiment of the
present invention, the coating compositions may include metal
catalysts which additionally provide a tint or coloration to the
resulting coating. Chromium acetate hydroxide is especially useful
in this regard, serving as a basic catalyst which provides a bluish
tint to the resulting coating. This feature may be especially
useful, for example, in connection with providing corrosion
resistant coatings to articles having large surface areas and/or
difficultly accessible regions, where visibility of the applied
coating can assure total coverage of the areas to be coated while
avoiding wasting coating by excessive applications over already
coated surfaces. For instance, addition of the chromium acetate
hydroxide catalyst has been successfully applied to coatings for
air conditioning units and other HVAC and heat transfer coils and
products, as described in Provisional Application No. 60/236,158,
filed Feb. 8, 2000, and its corresponding non-Provisional
Application, filed on even date herewith, titled "METHOD FOR
IMPROVING HEAT EFFICIENCY USING SILANE COATINGS AND COATED ARTICLES
PRODUCED THEREBY", under attorney docket number GED-6.
[0101] Other basic metal catalysts providing a colorant function
include, for example, iron acetate, iron acetate hydroxide,
chromium acetate, and the like. Other metal compounds such as
compounds of antimony, lead, barium, etc., also form colored
products, but tend to be more toxic and, therefore, less useful for
general purposes.
[0102] The present coating composition may be formed by mixing the
above-noted components and allowing them to react. A suitable
reaction time is tvpically 4 to 12 hours, if no colloidal aluminum
hydroxide and/or metal alcoholate is present. Shorter reaction
times may be obtained in the presence of colloidal aluminum
hydroxide and/or metal alcoholate.
[0103] If no lower alkanol is present, frequent shaking may be
necessary to achieve a shorter reaction time.
[0104] For ease of handling, the coating composition may be
provided as a two or three container system, e.g., the silane
component and any silicate component, if present, being provided in
a first container and all other components being provided in a
second or second and third container. The water may be provided
separately from the other components. The contents of the two or
three containers may be mixed shortly prior to use and allowed to
react for an appropriate reaction time, as noted above.
[0105] In accordance with another embodiment of the invention,
especially suitable for use in coating steel based substrates,
because no acid component is used, a coating composition is
prepared by admixing
[0106] (A) at least one silane of the formula (1)
R.sup.1Si(OR.sup.2).sub.3 (1)
[0107] wherein R.sup.1 and R.sup.2 are as defined above,
[0108] (B) base component, especially hydroxides of calcium, zinc,
and aluminum;
[0109] (E) epoxysilane; and
[0110] (D) water.
[0111] In this embodiment, the components (A), (B) and (E) may be
any of those described above in connection with the first
embodiment. Similarly, one or more of the other optional
ingredients, including, for example, the amino or keto silane
compounds of formula (4), silicate component (F), metal alcoholate
catalyst of formula (2), monoloweralkyl ether of alkylene glycol,
UV absorbers, solvents and co-solvents, etc., which may be included
in the coating compositions of the first embodiment may similarly
be used in the coating compositions of the second embodiment.
[0112] As the epoxy silane, component (E), mention may be made of,
for example,
glycidoxy(C.sub.1-C.sub.6-alkyl)(tri-C.sub.1-C.sub.3alkoxy)silan-
e, such as, 3-glycidoxypropyltrimethoxysilane,
3-glycidoxypropyldiisopropy- lethoxysilane,
(3-glycidoxypropyl)methyldiethoxysilane,
3-glycidoxypropyltriethoxysilane, and epoxy-functional silane
compounds represented by the formula (3)
OR.sup.10 2
[0113] wherein R.sup.10, R.sup.20 and R.sup.30, independently,
represent aliphatic or aromatic groups, especially, lower alkyl of
from 1 to 6 carbon atoms, preferably C.sub.1-C.sub.3 alkyl;
[0114] EP represents glycidyl (e.g., glycidyloxy), cyclohexane
oxide (epoxycyclohexyl) or cyclopentane-oxide (epoxycyclopentyl);
and
[0115] n is a number of from 1 to 4, preferably 1, 2 or 3.
[0116] As examples of the epoxy functional compounds represented by
formula (3), mention may be made of, for example,
gamma-glycidyloxymethyl- trimethoxysilane,
gamma-glycidyloxymethyltriethoxysilane,
gamma-glycidoxymethyl-tripropoxysilane,
gamma-glycidoxymethyl-tributoxysi- lane,
beta-glycidoxyethyltrimethoxysilane,
beta-glycidoxyethyltriethoxysil- ane,
beta-glycidoxyethyl-tripropoxysilane,
beta-glycidoxyethyl-tributoxysi- lane,
beta-glycidoxyethyltrimethoxysilane,
alpha-glycidoxyethyl-triethoxys- ilane,
alpha-glycidoxyethyl-tripropoxysilane,
alpha-glycidoxyethyltributox- ysilane,
gamma-glycidoxypropyl-trimethoxysilane, gamma-glycidoxypropyl-tri-
ethoxysilane, gamma-glycidoxypropyl-tripropoxysilane,
gamma-glycidoxypropyltributoxysilane,
beta-glycidoxypropyl-trimethoxysila- ne,
beta-glycidoxypropyl-triethoxysilane,
beta-glycidoxypropyl-tripropoxys- ilane,
beta-glycidoxypropyl-tributoxysilane,
alpha-glycidoxypropyl-trimeth- oxysilane,
alpha-glycidoxypropyl-triethoxysilane, alpha-glycidoxypropyl-tr-
ipropoxysilane, alpha-glycidoxypropyl-tributoxysilane,
gamma-glycidoxybutyl-trimethoxysilane,
delta-glycidoxybutyl-triethoxysila- ne,
delta-glycidoxybutyl-tripropoxysilane,
delta-glycidoxybutyl-tributoxys- ilane,
delta-glycidoxybutyl-trimethoxysilane,
gamma-glycidoxybutyl-trietho- xysilane,
gamma-glycidoxybutyl-tripropoxysilane, galma-alpropoxybutyl-trib-
utoxysilane, delta-glycidoxybutyl-trimethoxysilane,
delta-glycidoxybutyl-triethoxysilane,
delta-glycidoxybutyl-tripropoxysila- ne,
alpha-glycidoxybutyl-trimethoxysilane,
alpha-glycidoxybutyl-triethoxys- ilane,
alpha-glycidoxybutyl-tripropoxysilane,
alpha-glycidoxybutyl-tributo- xysilane,
(3,4-epoxycyclohexyl)-methyl-trimethoxysilane,
(3,4-epoxycyclohexyl)methyl-triethoxysilane,
(3,4-epoxycyclohexyl)methyl-- tripropoxysilane,
(3,4-epoxycyclohexyl)-methyl-tributoxysilane,
(3,4-epoxycyclohexyl)ethyl-trimethoxysilane,
(3,4-epoxycyclohexyl)ethyl-t- riethoxysilane,
(3,4-epoxycyclohexyl)ethyl-tripropoxysilane,
(3,4-epoxycyclohexyl)-ethyl-tributoxysilane,
(3,4-cpoxycyclohexyl)propyl-- trimethoxysilane,
(3,4-epoxycyclohexyl)propyl-triethoxysilane,
(3,4-epoxycyclohexyl)propyl-tripropoxysilane,
(3,4-epoxycyclohexyl)propyl- -tributoxysilane,
(3,4-epoxycyclohexyl)butyl-trimethoxysilane,
(3,4-epoxycyclohexy)butyl-triethoxysilane,
(3,4-epoxycyclohexyl)butyl-tri- propoxysilane,
(3,4-epoxycyclohexyl)butyl-tributoxysilane.
[0117] The amount of the components (A), (B) and (D) may generally
be the same amounts as previously disclosed for the first
embodiment.
[0118] The amount of component (E) epoxysilane will generally be
within the range of from about 1 to about 22 percent by weight,
preferably, from about 2 to 16% by weight, based on the total
weight of the composition.
[0119] According to still another embodiment of the invention, an
aqueous silane-based coating composition is formed by admixing as
component (A) at least one organosilane of formula (1), as given
above; (D) water; (J) (i) colloidal aluminum hydroxide or (ii)
metal alcoholate of the previously given formula (2) or a mixture
of (i) and (ii). Additional silane hydrolyzing catalyst, including,
for example, the compound of formula (4), or any of the other
disclosed aminosilane catalysts, effective to inhibit gellation,
may also be added in order to inhibit gellation and, thereby extend
storage life and pot life.
[0120] As examples of the organosilanes of formula (1) and metal
alcoholate of formula (2) the same compounds as mentioned above may
be used. Generally, the amount of organosilane(s) of formula (1)
will be from about 10 to 50%, preferably, 12 to 35%, and the amount
of the component (J) will be from about 0.05 to about 1.0 percent,
preferably, from about 0.1 to about 0.8%, each based on the total
weight of the composition
[0121] Representative of the additional silane hydrolyzing agent
and gellation inhibitor, the aforementioned epoxide silanes (E) are
especially preferred.
[0122] In another embodiment, an aqueous organosilane coating
composition is formed by admixing (A) at least one organosilane of
formula (1); (H) lower alkanol solvent; (D) water; and (K) chromium
acetate hydroxide or other silane polymerization catalyst which
will provide coloration to the resulting coating.
[0123] The amount of the component (K) is, usually, up to about 2
percent by weight of the coating composition, preferably from about
0.1 to about 1.8%, especially, from about 0.4 to about 1.3% by
weight, based on the total weight of the coating composition.
[0124] Here again, one or more optional ingredients, such as those
discussed in connection with other embodiments, may also be
included in the compositions of this embodiment.
[0125] According to another embodiment of the invention, an aqueous
based organosilane coating composition is formed by admixing (A) at
least one organosilane of formula (1); (D) water; (F) alkali metal
silicate, preferably pre-hydrolyzed; (H) lower alkanol solvent; (J)
(i) the aforementioned metal catalyst (i) colloidal aluminum
hydroxide; (ii) metal alcoholate of formula (2) as given above, or
(iii) mixture of (i) and (ii).
[0126] The components of the compositions of this embodiment, like
those of the previous alternatives, may be selected from the same
components and in the same amounts as previously described.
[0127] In accordance with still another embodiment of the
invention, an aqueous organosilane coating composition is formed by
admixing (A) at least one organosilane of formula (1); (B') at
least one basic amine silane catalyst, (D) water, (E) epoxide
silane: and (H) lower alkanol solvent.
[0128] As examples of the basic amine silane catalyst, (B'),
mention may be made of, for example, aminoethyl-triethoxysilane,
beta-amino-ethyltrimethoxysilane, beta-aaminoethyl-triethoxysilane,
beta-amino-ethyl-tributoxysilane, beta-aminoethyltripropoxysilane,
alpha-aminoethyl-trimethoxysilane,
alpha-aminoethyl-triethoxysilane,
gamma-aminopropyltrimethoxysilane,
gamma-aminopropyl-triethoxysilane,
gamma-aminopropyl-tributoxysilane,
gamma-amino-propyltripropoxysilane,
beta-aminopropyl-trimethoxysilane,
beta-aminopropyl-triethoxysilane,
beta-amino-propyltripropoxysilane,
beta-aminopropyl-tributoxysilane,
alpha-aminopropyl-trimethoxysilane,
alpha-aminopropyltriethoxysilane,
alpha-aminopropyl-tributoxysilane,
alpha-aminopropyl-tripropoxysilane,
N-aminomethylaminoethyl-trimethoxysilane,
N-aminomethylaminomethyl-tripro- poxysilane,
N-aminomethyl-beta-aminoethyl-trimethoxysilane,
N-aminomethyl-beta-aminoethyl-triethoxysilane,
N-aminomethyl-beta-aminoet- hyl-tripropoxysilane,
N-aminomethyl-gamma-aminopropyl-trimethoxysilane,
N-aminomethyl-gamma-aminopropyl-triethoxysilane,
N-aminomethyl-gamma-amin- opropyl-tripropoxysilane,
N-aminomethyl-beta-aminopropyl-trimethoxysilane,
N-aminomethyl-beta-aminopropyl-triethoxysilane,
N-aminomethyl-beta-aminop- ropyl-tripropoxysilane,
N-aminopropyltripropoxysilane, N-aminopropyl-trimethoxysilane,
N-(beta-aminoethyl)-beta-a.inoethyl-trime- thoxysilane,
N-(beta-aminoethyl)-beta-aminoethyl-triethoxysilane,
N-(beta-aminoethyl)-beta-aminoethyl-tripropoxysilane,
N-(beta-aminoethyl)-beta-aminoethyl-trimethoxysilane,
N-(beta-aminoethyl)-alpha-aminoethyl-triethoxysilane,
N-(beta-aminoethyl)-alpha-aminoethyl-tripropoxysilane,
N-(beta-aminoethyl)-beta-aminopropyl-trimethoxysilane,
N-(beta-aminoethyl)-galma-aminopropyl-triethoxysilane,
N-(beta-aminoethyl)-gamma-aminopropyl-tripropoxysilane,
N-(beta-aminoethyl)-gabmea-aminopropyl-trimethoxysilane,
N-(beta-aminoethyl)-beta-aminopropyl-triethoxysilane,
N-(beta-aminoethyl)-beta-aminopropyl-tripropoxysilane,
N-(gamma-aminopropyl)-beta-aminoethyl-trimethoxysilane,
N-(gamma-aminopropyl)-beta-aminoethyl-triethoxysilane,
N-(gamma-aminopropyl)-beta-aminoethyl-tripropoxysilane, N-methyl
aminopropyl trimethoxysilane, beta-aminopropyl methyl
diethoxysilane, gamma-diethylene triaminepropyltriethoxysilane, and
the like.
[0129] Of these, 3-(2-aminoethylamino)propyltrimethoxy silane [also
known as N-(2-aminoethyl)-3-aminopropyltrimethoxysilane], and
3-aminopropyltrimethoxy silane, are especially preferred.
[0130] Aminosilanes of formula (4), above, may also be used.
[0131] For the components (A), (D), (E) and (H), the representative
examples and amounts given above apply equally to this
embodiment.
[0132] In accordance with still another embodiment of the
invention, a multivalent catalyst system may be used to polymerize
the organosilane of formula (1). For example, the mixed multivalent
catalyst may include a divalent metal compound, such as hydroxide
or carbonate of calcium, magnesium or other alkaline earth metal; a
trivalent metal compound, such as, for example, boric acid or other
compound of boron or aluminum; and a tetravalent metal compound,
such as a compound of formula (2-a):
M.sup.1--(OR.sup.3).sub.4 (2-a)
[0133] where M.sup.1 represent a tetravalent metal, such as
titanium, or zirconium, and R.sup.3 is as previously defined.
[0134] According to this embodiment, the proportions of the
respective catalysts may be selected based on the desired
properties but generally in terms of metal ions, weight ratios of
M.sup.+2:M.sup.+3:M.sup.+4 of from about 0.1-1:0.05-1:0.1-2,
preferably from about 0.4-1:0.2-1:0.5-1, provide good results.
[0135] The multivalent catalyst system may be used with any of the
coating compositions described herein.
[0136] In one particular embodiment of the invention the subject
formulations are aqueous alcoholic formulations effective for
providing clear, hard and strongly adherent corrosion resistant
coatings for glass substrates, e.g., windows, mirrors,
counter-tops, table-tops, and the like, and also for providing
clear, hard, glossy and slick (slippery or wax-like) adherent
corrosion resistant coatings for metal surfaces, e.g., automobiles,
trucks, buses, trains, and other vehicles, metal signs, and the
like. According to this aspect of the invention, the coating
composition contains as the essential and major film-forming
components, a mixture of silane compounds of above formula (1),
wherein R.sup.1 in a first silane compound is a lower alkyl group,
such as methyl or ethyl while in a second silane compound, R.sup.1
is an aryl group, especially, phenyl. The ratio of the first silane
compound to second silane compound is not particularly critical and
may, generally, fall within a range of from about 3:1 to about 1:3,
preferably, from about 1.5:1 to about 1:1.5, such as about 1:1, on
a weight basis.
[0137] This composition will also include a small amount of
moderately alcohol soluble to alcohol soluble basic activator for
the silanes (either in the container, or in situ), especially,
calcium hydroxide or tetramethylammonium hydroxide. Generally, an
amount of calcium hydroxide, in the range of from about 0.4 to
about 4, preferably, from about 1.2 to about 2.8 parts of basic
activator, per 100 parts, in total, of silane compounds of formula
(1), will provide satisfactory results. Since tetramethylammonium
hydroxide tends to be more active and more soluble in alcohol than
calcium hydroxide, smaller amounts of this basic activator, should
be useful, for example, from about 0.01 to about 2, preferably,
from about 0.02 to about 1 part of tetramethylammonium hydroxide,
per about 100 parts of silane compounds of formula (1), should
provide satisfactory results.
[0138] For this particular embodiment, it is expected that
monovalent alkalis, such as, for example, sodium hydroxide,
potassium hydroxide, and the like would be too active for easy
application of the composition, while many other less active
alkalies, could require addition of acid catalyst to promote the
reaction, and therefore, would also not be preferred for the
intended applications to glass or painted metal substrates.
[0139] These formulations also include a silicate, preferably,
partially hydrolyzed silicate, such as, for example, hydrolysis
product of tetraethylsilicate, e.g., polydiethoxysiloxane (about
50% solids). Amounts of the silicate, on a solids basis, per 100
parts of silane compounds of formula (1), will usually fall within
the range of from about 1 to 16 parts, preferably, from about 2 to
about 10 parts, more preferably, from about 4 to about 8 parts.
[0140] The film-forming and catalyst ingredients are added to lower
alcohol solvent, preferably, isopropyl alcohol. Relatively dilute
solutions facilitate application by wiping (e.g., using a soft
cloth, sponge, etc.) or spraying. Generally, from about 600 up to
about 1500 parts of alcohol per 100 parts of silane compounds of
formula (1) provide satisfactory results.
[0141] An optional ingredient for this formulation is
.gamma.-glycidyloxypropyltrimethoxysilane, or other epoxy silane
compound, such as mentioned above.
[0142] As described above, the coating compositions of this
invention may be applied to a wide range of painted and non-painted
metallic, non-metallic, e.g., siliceous, ceramic, vitreous
substrates, including, for example, and not by way of limitation,
iron, steel, aluminum, copper, brass, bronze, other alloys,
plastics, e.g., polyolefins, polyesters, polyamides, polyimides,
polycarbonates, polyetherimides, polysulfones, and the like,
concrete, glass, alkali metal silicates, and the like. It is
particularly advantageous that the compositions of this invention
can be applied to even rusted metal substrates, e.g., rusted iron
or steel, and still provide strongly adherent and durable,
corrosion resistant coatings, especially if the substrate is
prewashed, such as, for example, with a composition comprising
water, isopropyl alcohol and acetic acid (e.g., from about 80 to
about 95 parts, preferably about 85 to about 92 parts, e.g., 89
parts, water; from about 4.9 to about 19 parts, preferably about 8
to about 14 parts, e.g., 10 parts, isopropyl alcohol;
[0143] and from about 0.1 to about 6, preferably about 0.5 to about
3, such as 1 part, acetic acid). The coating compositions of this
invention when applied to a substrate, such as those mentioned
herein, will readily penetrate even narrow and microscopic crevices
or pores of the substrate, to form strong adherent bonds with the
substrate. Although not wishing to be bound by any particular
theory of operation, it is believed that the penetration and
adherent bond formation is achieved, in part, because of the
absence of large organic molecules from the invention coating
systems.
[0144] The coating compositions contemplated herein may be
formulated as solventless, aqueous or non-aqueous systems
(although, in most cases, at least a catalytic amount of water is
eventually added, directly or taken from the atmosphere). For
example, the solventless systems may contain a mixture of
methyltrimethoxysilane and phenyltrimethoxysilane and, catalyst,
e.g., metal alcoholate, such as, for instance, tetrabutoxytitanate.
The solventless systems have been applied to brass and bronze
substrates to provide extremely durable and corrosion resistant
coatings (i.e., withstanding exposure to over 4000 hours of salt
water spray with no visible change). Suitable non-aqueous systems
(e.g., by addition of small amounts of diluent, especially, lower
alcohol, such as, isopropanol), may also be used, and such
non-aqueous systems are described in the Applicant's aforementioned
commonly assigned co-pending Provisional application Ser. No.
60/185,367, filed Feb. 28, 2000, the disclosure of which is
incorporated herein in its entirety, by reference thereto.
[0145] The coating composition may be applied in any conventional
manner, preferably by dipping, wiping, brushing or spraying.
Preferably, the spraying is carried out under an inert atmosphere,
especially using dry N.sub.2 propellant, as a result of which extra
gloss and hardness is imparted to the resulting coating. Although
the reason for this has not been ascertained, it is presumed that
nitrogen impacting the substrate surface removes at least some of
the adsorbed oxygen and water, while at the same time, its positive
Joule-Thomson coefficient retards solvent evaporation and promotes
film generation. Therefore, since any such adsorbed oxygen and/or
water would be expected to impair the qualities of the resultant
coating, the removal thereof by the N.sub.2 gas stream, would tend
to improve the qualities of the coating, including gloss and
hardness.
[0146] The present invention also provides corrosion resistant
primer coating compositions which are not only strongly adherent to
a broad range of metal substrates, including, for example,
aluminum, steel and galvanized steel, but also to a broad range of
pigmented and unpigmented topcoat materials, including, for
example, polyurethane resins, epoxy resins, acrylic resins,
polyester resins, alkyd resins, polyetherpolyester resins,
polycarbonate resins, and the like. Accordingly, the primer
compositions of this invention can be used without any other
tie-coat material.
[0147] According to this aspect of the invention, the primer
composition is prepared by admixing two or more polyfunctional
organosilanes as previously described. Monofunctional (e.g.,
organosilanes of formula (1) where R.sup.1 is alkyl or aryl) are
not included in the primer composition. Silica and silicate or
precursors thereof are also not included in the primer
compositions.
[0148] At least one of the polyfunctional organosilanes will
preferably include polyamino group as R.sup.1 in formula (1),
namely, aminosilanes of the following formula (1-A)
H.sub.2N--R.sub.a--NH--R.sub.b--Si(OR.sup.2).sub.3 (1-A)
[0149] where R.sub.a and R.sub.b are each, independently, alkyl of
from 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms,
especially 2 to 4 carbon atoms; and R.sup.2 is as defined
above.
[0150] Aminoethylaminopropyltrimethoxysilane,
aminoethylaminobutyltrimetho- xysilane,
aminoethylaminopropyltriethoxysilane, can be mentioned as
representative of aminosilane compounds of formula (1-A).
[0151] While the polyaminopolyfunctional organosilanes are
preferred, other polyfunctional organosilanes, such as
vinylsilanes, acrylic silanes, methacrylic silanes, and the like,
as described above, may be used in place of, or in addition to, the
polyaminopolyfinctional organosilanes.
[0152] At least one other polyfunctional organosilane which is an
epoxysilane, including any of the epoxysilanes as component (D)
mentioned above, is also preferably included as one of the
polyfunctional organosilanes of the primer coating composition.
Especially, mention may be made of the glycidyloxy
(C.sub.1-C.sub.6-alkyl)(tri-C.sub.1-C.sub.3 alkoxy) silanes, such
as 3-glycidyloxypropyltrimethoxysilane, for inclusion in the primer
coating composition.
[0153] Suitable amounts of the polyfunctional organosilanes in the
primer coating composition, as solids (non-volatile silanol
condensation products after addition of water) will generally range
from about 1% to about 20%, by weight, preferably from about 2 to
about 15%, more preferably from about 4 to 12%, by weight, of the
composition. These amounts will typically, for a primer containing
two of the polyfunctional silane compounds, correspond to from
about 2 to about 40%, preferably from about 4 to about 30%, more
preferably from about 8 to about 24%, by weight, of the total
composition, in the as prepared composition, before water
addition.
[0154] Thus, in a preferred composition containing a mixture of (a)
polyaminoorganosilane and (b) glycidyloxyorganosilane, in
appropriate volatile organic solvent, preferably isopropyl alcohol,
the total amount of (a) plus (b) is preferably from about 5 to
about 25 parts, more preferably, from about 10 to about 20 parts,
per 100 parts of volatile organic solvent. Furthermore, weight
ratios of (a):(b) in the range of from about 1:0.4 to 2, preferably
1:0.6 to 1.4, have been found to provide especially good
results.
[0155] In use, the organic solvent, e.g., isopropyl alcohol,
solution of the polyfunctional organosilanes, is thoroughly mixed
with a small amount of water to catalyze the hydrolysis reaction.
The resulting formulation is then generally ready to be applied to
the substrate in from about 5 minutes to about 1 hour, typically,
in about 10 to about 30 minutes, such as about 15 minutes.
[0156] Only a minor amount of water, such as from about 1 to 2
parts water per 100 parts of solution (e.g., from about 0.5 to 1.0
parts water per 10 parts polyfunctional silanes) will be sufficient
to catalyze the hydrolysis reaction.
[0157] The primer composition may be applied to the substrate in
any convenient manner, such as by wiping, brushing, dipping and
spraying. Since the subject primer coating compositions do not form
lumps, it is easy and convenient to apply by spraying, for example,
using a number 4-6 nozzle with a pressure of about 20 psi.
Preferably, the spray is in the form of a mist. It is not necessary
to apply the composition uniformly since the coating will tend to
flow together to provide a uniform continuous film.
[0158] Although the precise nature of the resulting primer coating
is not known, it will be recognized by those skilled in the art
that the polyfunctional silanes provide multiple reactive sites for
adhering to the substrate, to itself and each other, as well as to
the subsequently applied top coat.
[0159] Presumably, because of the strong adhesion to the substrate,
resulting from the multiple reactive sites, the primer coating is
extremely corrosion resistant, as will be shown from the examples
provided hereinafter. Accordingly, the primer coating compositions
of this invention can be used for many different applications where
exposure to alkali and/or acid corrosive agents is anticipated, for
example, in the automotive industry as a primer for resin paint
finishes.
[0160] Generally speaking, the silane coating compositions
according to the present invention have a broad scope of useful
applications. The following are representative, but non-limiting,
examples of applications in which one or more of the compositions,
as described above, and in the following Examples, have been or may
be used, with good results.
[0161] 1. Protection of aluminum, steel, galvanized steel,
stainless steel, brass, bronze, copper, silver, and other metals,
from corrosive environments, including, as examples, salt water,
hydrochloric acid, sulfuric acid, phosphoric acids, and the
like.
[0162] 2. Protection of interior and exterior building materials,
such as, for example, ceramic roofing tiles, concrete, and
galvanized steel, including interior surfaces of duct works, from
deposition and growth of mildew and infectious organisms.
[0163] 3. Overcoating and/or removal of graffiti from coated or
uncoated concrete and metallic surfaces, without sacrificing the
coating, when present.
[0164] 4. Corrosion protection and maintenance of cooling and
heating efficiencies of HVAC and other heat exchange equipment.
[0165] 5. Corrosion resistant primer for various finishes,
including, for example, urethane, epoxy, polyester, latex, and the
like.
[0166] 6. Overcoating for automotive and truck (e.g., cement
truck), bus, and other vehicle, finishes.
[0167] 7. Corrosion protection for food and beverage container
surfaces in contact with foods, beverages, and the like, e.g.,
aluminum cans.
[0168] 8. Overcoating and containing rust.
[0169] 9. Coating fasteners, e.g., screws, bolts, rivets, and the
like.
[0170] 10. Barnacle release agent.
[0171] 11. Protective, corrosion resistant and release surface, for
manifolds, exhaust systems, cooking utensils, ovens, and other
equipment exposed to temperature extremes.
[0172] 12. Corrosion protection and/or deicing agent for aircraft
wings and other surfaces.
[0173] 13. Coating for glass surfaces in coastal environments to
facilitate cleaning.
[0174] 14. Wipe-on finish protector and refurbisher for automotive
and other vehicle, equipment finishes.
[0175] 15. Gel-coat maintenance finish.
[0176] 16. Protective coating for maintaining asphalt tiles.
[0177] For any of the above applications, only thin coatings, on
the order of about 2000 nm, or less, will provide good results.
Generally, the coating compositions of the present invention are
effective when applied to a coating (film) thickness (after cure)
in the range of from about 5 to about 150 millionths of an inch,
however, if desired to provide even superior corrosion protection,
thicker films may be applied.
[0178] The following examples are illustrative and are not intended
to limit the invention in any way. Unless stated otherwise, all
parts and percentages are by weight. In the following examples the
water used is distilled or deionized water.
EXAMPLE 1
[0179] In a first container, methyltrimethoxysilane,
phenyltrimethoxysilane and propyltrimethoxysilane are mixed in
amounts of 15 parts, 1 part and 5 parts, respectively. In a second
container, aminoethylaminopropyltrimethoxysilane
{N-(2-aminoethyl)-3-aminopropyltrim- ethoxysilane}, water, acetic
acid, and titanium dioxide (average particle size, 22nm), are mixed
in amounts of 0.2 part, 13 parts, 0.4 part, and 0.2 part,
respectively. After combining the contents of the two containers,
the resulting mixture is allowed at least four hours to homogenize.
Faster homogenization will be achieved by using a mechanical shaker
or stirrer. The so-formed liquid mixture may be applied by wiping,
foam brushing, conventional brushing or spraying using dry nitrogen
as propellant to boats or automobiles for restoration. After 24
hours, the reaction may be applied to, for example, boats and
automobiles. The resulting coatings perform satisfactorily for over
one year without visual change. In this example, the titanium
dioxide functions as a UV absorber. The TiO.sub.2 may, however, be
omitted, with similar results by replacing acetic acid with an
equivalent amount of metal alcoholate, such as tetrabutoxy
titanate.
EXAMPLE 2
[0180] In a first container, phenyltrimethoxysilane,
methyltrimethoxysilane and tetrabutoxy titanate are mixed in
amounts of 5 parts, 15 parts and 0.3, 0.4, 0.5 or 0.6 part,
respectively. In a second container, isopropyl alcohol and an
aqueous 3% boric acid solution are mixed in amounts of 13 parts and
13 parts, respectively. After combining the contents of the two
containers, the resulting mixture is ready for application after
about three hours. The resulting mixture may be applied, for
example, to aluminum, brass, bronze, copper, silver, steel,
stainless steel or galvanized steel, by spraying (e.g., with
N.sub.2 propellant) to provide corrosion protection, including in
saline atmospheres, such as, for example, on boats, ships and
aircraft. This composition may also be advantageously applied to
food and beverage container surfaces that come into contact with
foodstuffs, beverages, and the like, e.g., aluminum cans.
EXAMPLE 2A
[0181] The procedure of Example 2 is generally followed, except
that isopropyl alcohol is omitted. To 15 parts
methyltrimethoxysilane, there is added, while stirring, 5 parts
propyltrimethoxysilane or 5 parts phenyltrimethoxysilane. To this
mixture, 0.3 parts boric acid is added followed by addition of 0.2
to 0.3 parts tetrabutoxytitanate.
[0182] The mixture is allowed to clear. Then, 10 to 13 parts of
water is added slowly to avoid excessive heat build-up. The
resulting composition may be applied to a substrate while it is
still warm or after further heating by reaction. Alternatively, the
composition may be stored and applied after as long as about 6 days
after water addition. Application may be by spraying, wiping,
brushing ,etc.
EXAMPLE 2B
[0183] As another example of an organic-solvent free composition of
this invention, a mixture of 15 parts methyltrimethoxysilane and 5
parts phenyltrimethoxysilane is combined with 0.2 to 0.35 parts of
tetrabutoxytitanate. While stirring, 2.4 parts water is added.
After about 15 minutes the resulting composition is ready to be
applied to a metal or non-metal substrate.
[0184] This composition may be used, for example, on brass, steel
and stainless steel substrates, including as an over coating for
stainless steel primed with the primer composition of this
invention, see, e.g., Example 30, below. Similarly, this
composition may be used as an overcoat for primed aircraft wings or
other surfaces for corrosion protection and/or as deicing agent.
When applied as an overcoating layer for substrates primed with a
primer coating of this invention, this coating is also useful for
protection corrosion resistance and as release surface for high
temperature applications, such as manifolds, exhaust systems,
cooking utensils, ovens, and the like.
[0185] Other applications for the coating composition of this
example include, for instance, corrosion protection for food and
beverage container surfaces that come into contact with foods,
beverages and the like, especially aluminum cans.
[0186] The coating composition of this example may be used, for
example, for corrosion protection of aluminum substrates, including
in saline atmospheres, such as may be encountered on boats, ships
and aircraft.
[0187] This composition may also be advantageously applied for the
protection of interior and exterior building materials from, for
example, deposition and growth of mildew or infectious organisms,
especially in salt air environments, such as coastlines, industrial
areas and the like.
[0188] For instance, the composition may be used to coat ceramic
roofing tiles, concrete, galvanized steel, duct works (e.g.,
interior surfaces), etc.
[0189] Another application of the coating composition of this and
other examples given above and hereinafter, especially when used as
a topcoat in combination with the primer compositions of this
invention, is for corrosion protection and/or as deicing agent for
aircraft wings and other surfaces exposed to subfreezing
temperatures.
EXAMPLE 3
[0190] 5 parts of phenyltrimethoxysilane are added to a container
containing 15 parts methyltrimethoxysilane. While mixing, 0.3 part
of tetrabutoxy titanate are added, along with 2 parts of
polydiethylsiloxane (approx. 50%), and 15 parts of isopropyl
alcohol. After mixing, 10 parts of an aqueous 3% boric acid
solution are added and, after waiting eight hours, the resulting
coating composition is applied, by dipping or spraying (with
N.sub.2 propellant), to steel, aluminum and brass coupons. The
cured compositions will be corrosion resistant.
[0191] In this example, similar results will be obtained when,
instead of 0.3 part of tetrabutoxy titanate, 0.4, 0.5 or 0.6 part
of tetrabutoxy titanate are used.
EXAMPLE 4
[0192] 17 parts methyltrimethoxysilane, 3 parts
phenyltrimethoxysilane, 20 parts isopropyl alcohol and 2.5 parts
polydiethylsiloxane (.about.50%), are mixed. 5 parts of an aqueous
5% solution of phosphorous acid are added, and allowed to react, to
form a coating composition.
EXAMPLE 5
[0193] 16 parts of methyltrimethoxysilane and 5 parts of
propyltrimethoxysilane are mixed in a first container. 20 parts of
isopropyl alcohol, 10 parts of polydiethylsiloxane, which has been
hydrolyzed to 52% silica, and 5 parts of an aqueous 1.25% solution
of phosphorous acid are mixed in a second container. The contents
of the two containers can then be mixed together and allowed to
react to form a coating composition.
EXAMPLE 6
[0194] 0.2 part of aminoethylaminopropyltrimethoxysilane, 0.4 part
of acetic acid and 13 parts of water are mixed in a first
container. 15 parts of methyltrimethoxysilane, 1 part of
phenyltrimethoxysilane and 5 parts of propyltrimethoxysilane are
mixed in a second container. The contents of the two containers can
then be mixed together and allowed to react to form a coating
composition.
EXAMPLE 7
[0195] 10 parts of a 3% boric acid solution are placed in a first
container. 20 parts of methyltrimethoxysilane, 10 parts of
isopropyl alcohol and 0.5 part of tetrabutoxy titanate are mixed in
a second container. The contents of the two containers can then be
mixed together and allowed to react to form a coating
composition.
[0196] By eliminating isopropyl alcohol, the rate of emulsification
can be increased by increasing batch size.
EXAMPLE 8
[0197] 15 parts of methyltrimethoxysilane, 5 parts of
isobutyltrimethoxy-silane and 1.1 parts of polydiethylsiloxane
(.about.50%), are mixed in a first container. 0.2 part of
aminoethylaminopropyltrimethoxysilane, 0.4 part of acetic acid, 13
parts of water, 1.5 parts of ethylene glycol monoethyl ether and
0.5 part of titanium dioxide (average particle size of 22 nm) are
mixed in a second container. After mixing, the contents of the two
containers will react to form a coating composition.
EXAMPLE 9
[0198] 20 parts methyltrimethoxysilane and 20 parts isopropyl
alcohol are mixed to form a homogeneous silane-alcohol solution.
Six (6) parts of a saturated solution of calcium hydroxide is added
to catalyze the silane-alcohol solution. The reaction is allowed to
proceed until the temperature peaks before acidifying. The reaction
time may be longer or shorter, depending on the batch size, since
the exothermic reaction temperature is dependent on batch size.
Moreover, for batch sizes of about 1 liter or more, artificial
cooling may be required.
[0199] Increased stability may be obtained by adding 0.3 part of
acetic acid in place of the 0.6 grams of chromium acetate.
[0200] This coating composition may be used, for example, for
protection of interior and exterior building construction
materials; as a washable overcoating for protection of surfaces,
such as concrete and metallic surfaces, subject to application of
undesirable graffiti or otherwise which may be subject to repeated
solvent cleaning operations; as an overcoating for protection of
finishes on automotive, truck (including construction trucks, such
as cement trucks), buses and other vehicles; as protection of
surfaces on containers that come into contact with foodstuffs and
beverages, especially aluminum cans; as a protective, corrosion
resistant and release surface coating for surfaces exposed to high
temperatures, such as, for example, manifolds, exhaust systems,
cooking utensils, ovens, etc.; for corrosion protection and/or
deicing agent for aircraft wings and other surfaces facing exposure
to subfreezing temperatures (especially as an overcoating in
combination with the primer compositions of this invention); as a
wipe-on finish protector and refurbisher for automotive and other
vehicle equipment finishes; as a gel-coat maintenance finish; and
the like.
EXAMPLE 10
[0201] In this example the procedure of Example 9 is repeated
except that instead of catalyzing the silane-alcohol mixture with
calcium hydroxide a mixture of 0. 15 molar Ca(OH).sub.2 and 0.08
molar Zn(OH).sub.2 is used. After addition of the base catalysts
the resulting solution is allowed to react for about I hour and is
then applied to a steel substrate using dry N.sub.2 as propellant,
to a coating thickness of 0.5 mil. The coating is cured by baking
at 80.degree. C. for 5 minutes or at 62.degree. C. for 20 minutes.
The resulting cured coating is able to withstand immersion in 5%
HCl for at least 45 minutes before failure.
[0202] To the unused portion of the base catalyzed reaction mixture
0.2 grams of acetic acid may be added to inhibit gellation. After
standing for from 3 to 5 days the composition may be applied to an
aluminum or other substrate. The coating may be allowed to cure,
under ambient conditions.
EXAMPLE 11
[0203] 20 parts of methyltrimethoxysilane, 10 parts of isopropyl
alcohol and 0.2 parts of magnesium ethoxide are mixed until the
solution becomes homogeneous. A base catalyst (a saturated solution
of a mixture of calcium hydroxide, calcium carbonate and magnesium
carbonate, diluted with 2 parts water), is then added, and the
resulting formulation is allowed to react for about 1 hour.
[0204] The resulting mixture may be applied to steel substrate to a
thickness of about I mil or less, and baked at about 150.degree. C.
for about 5 minutes. The resulting coating will be able to
withstand immersion in 5% HCl for at least 15 minutes without
change.
[0205] To extend pot life, 0.3 parts of
3-glycidoxypropyltrimethoxysilane, mixed with 10 parts of isopropyl
alcohol, is added to the catalyzed reaction mixture. After
hydrolysis, the resulting coating composition may be applied by
spraying on steel and aluminum coupons.
EXAMPLE 12
[0206] A silane-alcohol mixture is prepared as in Example 9 (Pot
A). Separately, there is prepared a mixture (Pot B) obtained by
combining 11.3 parts of a 3% solution of boron methoxide in
isopropyl alcohol, 2 parts of polydiethoxysiloxane (.about.50%
solids), 0.4 parts of tetrabutoxytitanate, and 2 parts of
methyltrimethoxysilane. The mixture in Pot B is allowed to react
for 24 hours and is then added to the silane-alcohol solution in
Pot A. The resulting mixture of Pots A and B may be applied to
steel and aluminum coupons by spraying under dry N.sub.2 propellant
to form a coating.
EXAMPLE 13
[0207] To a base catalyzed reaction mixture prepared in the same
way as in Example 10 (Pot A), there was added the contents of Pot
B, obtained in the same way as for Pot B in Example 12, except that
in place of the 0.4 parts of tetrabutoxytitanate, 0.44 parts of
iron ethoxide is used. Similar results to the results of Example 12
will be obtained.
EXAMPLE 14
[0208] After thoroughly mixing 20 parts methyltrimethoxysilane with
10 parts isopropyl alcohol, 0.2 parts of
aminoethylaminopropyltrimethoxysila- ne is added to the resulting
silane-alcohol mixture, and again thoroughly mixed. Then 6 parts of
water is added to the resulting mixture and, after standing for 90
minutes, the resulting coating composition is applied to steel and
aluminum coupons by spraying using dry nitrogen propellant.
[0209] The resulting coatings may be allowed to cure under ambient
conditions to form acid resistant.
[0210] The above coating composition may be stabilized to obtain a
longer pot life, using any of the stabilizers as shown, for
example, in any of the preceding examples, including, acetic acid,
chromium acetate hydroxide, 3-glycidyloxypropyltrimethoxysilane
(phenyltrimethoxysilane).
EXAMPLE 15
[0211] The procedures of Example 14 are repeated except that in
place of 3-(2- aminoethylamino)propyltrimethoxysilane, an equal
amount of 3-aminopropyltrimethoxysilane is used with similar
results being obtained.
EXAMPLE 16
[0212] 20 parts of methyltrimethoxysilane and 20 parts isopropyl
alcohol are mixed and the resulting mixture is combined with 0.25
parts of aluminum isopropoxide under stirring until the aluminum
isopropoxide is partially dissolved. To this mixture 6 parts water
is added. After stirring for about one hour, the mixture is ready
for applying to the intended substrate, by brushing, spraying, etc.
To extend pot life, phenyltrimethoxysilane may be introduced to the
coating composition.
EXAMPLE 17
[0213] 140 parts methyltrimethoxysilane and 140 parts isopropyl
alcohol are mixed and catalyzed using 2.8 parts of aluminum
isopropoxide. The resulting mixture is stirred until the catalyst
is dissolved, after which 42 parts of water are added. The reaction
is complete when the mixture is nearly at room temperature. The
reaction mixture is applied, by spraying, using dry N.sub.2
propellant, to galvanized iron, and to the inside of aluminum cans,
e.g., as can inner liner. In the case of the galvanized iron, the
coating is allowed to cure at ambient over 7 days. For the aluminum
can, curing is by heating at 150.degree. C. for 2 minutes.
[0214] The coatings of this and the other examples, do not include
large organic (i.e., insulating) molecules and tend to be good
conductors of electrical charge and may be applied to various
electric appliances, such as power boxes, to provide a corrosion
resistant coating which does not interfere with the flow of
electric current. Similarly, the compositions of the present
invention may be applied as very thin coatings, on the order of
about 2000 nm or less, they tend to be good thermal conductors.
Therefore, they are highly useful for providing corrosion
resistance to HVAC units and other heat transfer surfaces. The
composition of this example may also be applied for protection of
aluminum surfaces.
EXAMPLE 18
[0215] This example shows that rare earth metal compounds will also
function as the catalyst for the silane polymerization reaction. 15
parts methyltrimethoxysilane, 5 parts phenyltrimethoxysilane , 20
parts isopropyl alcohol, and 2 parts polydiethoxysiloxane (-50%
solids), are mixed together with 0.4 parts cerium isopropoxide
until the latter is dissolved. Then, 6 parts of water are added to
complete catalysis. The resulting mixture is allowed to react for
about 3 hours, after which it is applied, by spraying with dry
N.sub.2 propellant, to aluminum and to steel substrates, to a wet
thickness of 1 mil. After curing, the resulting coating will be
corrosion resistant and free of pinholes.
[0216] To the unused portion of the above coating composition, 0.2
parts of phenyltrimethoxysilane is added. The mixture will
stabilize after about 1 hour, and thereafter the 1 o composition is
applied to aluminum and steel substrates to a wet thickness of
about 1 mil or less.
[0217] After ambient curing for 6 days, the coatings are similarly
resistant to hydrochloric acid, as noted by immersion in the above
described copper sulfate solution.
[0218] The composition of this example may be sold as a two or
three part formulation, for example, the silanes and alcohol in one
container, the catalyst in a second container, and the distilled or
deionized water supplied separately or pre-mixed with either of the
other two containers.
EXAMPLE 19
[0219] This example shows the use of a double metal alkoxide
catalyst for the silane coating composition. A uniform solution,
obtained by mixing 15 parts methyltrimethoxysilane, 5 parts
phenyltrimethoxysilane, 20 parts isopropyl alcohol, and 2 parts
polydiethoxysiloxane (50% solids) is catalyzed with 6 parts of an
alcoholic (isopropyl alcohol) solution of a double alkoxide of
aluminum and titanium. The resulting mixture is allowed to react
for about 4 hours using six parts water. The resulting coating
composition may be applied to steel by spraying, using dry N.sub.2
propellant, to a wet thickness of about 1 mil and then baked at
82.degree. C. for 5 minutes. No pinholes will be observed when the
resulting coated substrate is immersed in an acidic copper sulfate
solution as described above.
[0220] To an unused portion of the above catalyzed composition, 0.2
parts of phenyltrimethoxysilane is added. After ambient curing for
6 days, the resistance will be equivalent to that of the
composition without phenyltrimethoxysilane.
[0221] The stabilized phenyltrimethoxysilane coating composition
may be applied as an overcoating on a potassium silicate coated
concrete and will cure in about 3 days. After 5 days, the
overcoated product may be immersed in water for at least 6 weeks
without an observable change.
[0222] This composition may be applied, for example, to overcoat
and contain rust aboard ocean going vessels.
EXAMPLE 20
[0223] To a mixture formed by combining 20 parts
methyltrimethoxysilane, 20 parts isopropyl alcohol, and 2 parts
polydiethoxysiloxane (.about.52% solids), there is added a catalyst
containing 0.6 parts boron methoxide and 0.2 parts aluminum
isopropoxide. After the solids are dissolve, water (6 parts) is
added to complete the catalysis. The resulting mixture is allowed
to stand (react) for about 1 hour. The reaction product may be
applied to steel and aluminum coupons to wet thicknesses of 1 mil
and 0.5 mi, respectively, and allowed to cure under ambient
conditions for about 7 days. In this example, the titanate and
boron ethoxide each function to hydrolyze ethyl silicate. These
compositions have good stability and, consequently, a very long pot
life.
[0224] This composition has been found to be effective, for
example, as an overcoating for protecting and containing rust
aboard ocean going vessels.
EXAMPLE 21
[0225] Following the same procedure as in Example 20, except that
0.4 parts by weight of iron ethoxide is used in place of the boron
ethoxide and tetrabutoxytitanate, similar results will be obtained.
The iron ethoxide adds an orange-red tint to the coating.
EXAMPLE 22
[0226] This example shows the formation of a coating composition
which does not use a metal compound catalyst.
[0227] 20 parts methyltrimethoxysilane, and 20 parts isopropyl
alcohol, are mixed with 0.2 parts of
aminoethylaminopropyltrimethoxysilane (as hydrolysis catalyst).
After thoroughly mixing with 6 parts water, the mixture is allowed
to react (hydrolyze) for 45 minutes. Then, the mixture is combined
with 0.3 parts phenyltrimethoxysilane predispersed in 10 parts
isopropyl alcohol. After about 1 hour, the composition is ready to
be applied, by wiping, on stainless steel, or an acrylic coating on
steel, on aluminum, etc. Further stabilization may be promoted by
adding 0.2 to 0.3 parts of a silyl epoxide.
[0228] The coating composition of this example may also be used
advantageously as a primer for a powder, e.g., epoxy, coating. In
this case, after heating, the coating may be subjected to a
cross-hatch (1 mm separation test). No adhesion loss is
observed.
[0229] If in the above composition, the 0.2 parts of
aminoethylaminopropyltrimethoxysilane is replaced with
aminopropyltrimethoxysilane, similar results will be obtained.
EXAMPLE 23
[0230] 15 parts methytrimethoxysilane, 5 parts
phenyltrimethoxysilane, 6 parts (.about.50%) polydiethoxysiloxane
(50%), and 20 parts isopropyl alcohol are combined with 0.4 parts
aluminum isoproxide. After stirring until the catalyst is
dissolved, 6 parts of water are added. After mixing the aqueous
mixture for an additional fifteen minutes, the mixture is ready for
use as a corrosion resistant coating composition. Corrosion
resistant coatings are obtained on stainless steel, mild steel,
aluminum, brass fixtures, bronze coupon, and galvanized iron by,
for example, dipping or spraying with dry nitrogen propellant. In
addition, the coating composition may be applied as an overcoating
on a potassium silicate coated concrete (previously cured for 3
days). After curing for 7 days, the coating does not swell or
change even after immersion in water for six weeks.
[0231] The coating formed in this example has a "glass-like"
appearance and quality. It is presumed that the silica bonds (via
oxygen) to and seals the metal substrate, whereas the phenyl groups
from phenyltrimethoxysilane tend to rise to the surface forming a
hard coating.
EXAMPLE 24
[0232] This example shows a three part mixed valence catalyst
system for silane catalyzation. In particular, tetrabutoxy titanate
(Ti+4) functions as the primary catalyst, boric acid (B+3) as
secondary catalyst and calcium hydroxide (Ca+2) as tertiary
catalyst. Together, these three catalysts are believed to enter the
ethyl polysilicate into the final matrix and thereby create a
nonporous silicone coating.
[0233] It has been found that this composition, even without
addition of a stabilizer, has a pot life of about 2 days. These
coating compositions provide excellent corrosion resistance, as
seen from the results in the acid immersion test.
[0234] Twenty (20) parts methyltrimethoxysilane, 5 parts
phenyltrimethoxysilane and 20 parts isopropyl alcohol are combined
and thoroughly mixed. To this mixture is first added 0.2 parts of
boric acid followed by addition of 4 parts of polydiethoxysiloxane
(50%). After the boric acid is dissolved, 0.6 parts tetrabutoxy
titanate and then 6.5 parts water are added. By adding the water
slowly, premature hydrolysis of the tetrabutoxy titanate may be
prevented. After about one hour, 1.6 parts of a 0.5%
solution-suspension of calcium hydroxide in isopropyl alcohol is
added and the mixture is allowed to react for at least one
hour.
[0235] A steel coupon coated with this mixture (e.g., by spraying
using dry N.sub.2 propellant) and cured, e.g., by heating to
80.degree. C. for 5 minutes, was found to be highly resistant to
corrosion (no formation of visible pinholes) even after immersion
in a 20% solution of copper sulfate in 5% HCl for 24 hours. In
fact, this coating will provide corrosion resistance comparable or
superior to commercially available epoxy coating compositions.
[0236] This composition may be used, for example, as a protective
coating for aluminum, steel, stainless steel substrates, and
especially, as an overcoating on rusted surfaces aboard ocean going
vessels.
EXAMPLE 25
[0237] The following composition is prepared and may be used, for
example, in coating steel.
[0238] Twenty parts of methyltrimethoxysilane are combined with 5
part of phenyltrimethoxysilane in a container to which is added 4
parts of a polydiethylsiloxane hydrolyzed to about 50% solids. To
this mixture is added 0.3 parts boric acid. The mixture is stirred
until the boric acid is dissolved. Next, 0.5 parts of
tetrabutoxytitanate are added, while stirring is continued.
Finally, 6.7 parts of water are slowly added to avoid a color
change. After the catalyzed reaction proceeds for about two hours,
the mixture may be applied to steel panels by spraying, using dry
N.sub.2. The coating will cure under ambient conditions in about
one week. The resulting coating can withstand immersion in HCl bath
for a minimum of two hours. It is believed that the boric acid,
which is not corrosive to steel, forms a chemically inert
borosilicate glass-like reaction product.
EXAMPLE 26
[0239] This example shows a formulation suitable for providing a
salt, mildew and streak resistant coating for glass substrates,
e.g., windows, especially in corrosive environment, such as in
seaside dwellings.
[0240] To a container containing 600 parts of isopropyl alcohol
there is added, while stirring, 24 parts of methyltrimethoxysilane
and an equal amount of phenyltrimethoxysilane. To this mixture,
there is added 6 parts of polydiethoxysiloxane (.about.50% solids)
and one part of calcium hydroxide. Stirring is continued until the
mixture remains cloudy, and then, 5.4 parts of water are added
while stirring is continued.
[0241] The resulting coating may be applied to a glass window
substrate by, for example, wiping. After evaporation of isopropyl
alcohol, the surface can be polished, using a soft cloth or sponge,
until it feels slick to the touch. An additional application may be
necessary under severe conditions. The surface may require washing
(e.g., with a dilute aqueous surfactant). If necessary, residual
coating may be removed from the window, etc. by scraping (e.g.,
with a razor blade) followed by rinsing with alcohol (e.g.,
isopropyl alcohol).
[0242] Similar results are obtained when this composition is
applied to metal (e.g., aluminum, steel, galvanized steel)
substrates.
EXAMPLE 27
[0243] This example shows that formulations according to the
present invention are strongly adherent to rusty metal
substrates.
[0244] To a container containing 10 parts of polydiethoxysiloxane
(.about.50%) is added 20 parts of isopropyl alcohol and 0.2 parts
of aluminum isopropoxide, followed by 5 parts of
phenyltrimethoxysilane. The mixture is stirred until it becomes
clear. At that time, while continuing stirring, 2.3 parts of water
are added, followed by 5 parts of phenyltrimethoxysilane. After
stirring for about 3 hours, the mixture is applied over rusty steel
windshield wiper holders (any loose, flaky rust is first manually
removed). After more than six weeks of exposure, including several
heavy rain storms, no rust is visible through the coating. The
coating in this example contains approximately 56% silica, mostly
as iron silicate.
EXAMPLE 28
[0245] To a container containing I0 parts of polydiethoxysiloxane
(approx. 50%) is added, while stirring, 20 parts of isopropyl
alcohol and 0. 1 part of boric acid. Stirring is continued until
the solution becomes clear. Then, 0.2 parts of titanium tetrabutoxy
oxide are added. The mixture is stirred for about 3 hours. Then,
2.3 parts of water are added, while stirring, followed by 5 parts
of phenyltrimethoxysilane. After stirring for an additional about 3
hours, the solution may be applied to metal, glass or ceramic
substrates.
EXAMPLE 29
[0246] To a container containing 20 parts of isopropyl alcohol,
there is added 15 parts of methyltrimethoxysilane, 5 parts of
phenyltrimethoxysilane, 0.2 parts of boron methoxide, and 0.3 parts
of aluminum isopropoxide. The mixture is stirred until the aluminum
isopropoxide is dissolved.
[0247] Catalysis is completed by adding 6 parts water. Depending on
the batch size, cooling may be required to control the reaction and
reaction temperature.
EXAMPLE 30
[0248] This is an example of a primer coating composition according
to this invention.
[0249] Into a container is placed 420 parts of isopropyl alcohol,
45 parts of aminoethylaminopropyltrimethoxysilane and 3 5 parts of
3 -glycidoxypropyltrimethoxysilane. These ingredients are
thoroughly mixed prior to adding 6 parts of water. The formulation
is ready for use in about fifteen minutes and provides a solids
loading, as silanol condensation products, of about 8% by
weight.
[0250] The formulation may be applied to aluminum, galvanized
steel, steel, etc. After becoming tacky, each of the substrates is
top coated with, for example, a polyurethane resin or an epoxy
resin. After ambient cure for about 24 hours, each over coated
sample, and each primed substrate (without topcoat), is put into a
salt spray environment operating between ambient temperature and
180.degree. F. with 5 psi salt (20% solution) impinging on the
coated topcoated or primed substrate. After at least 8 days, no
creep or degradation on any of the samples is observed.
[0251] Similar results will be obtained when the proportions of the
aminosilane and glycidyloxysilane are reversed.
[0252] Similar results will also be obtained using acrylic resins,
polyester resins, and alkyd resins as the topcoat.
EXAMPLE 31
[0253] This example is similar to Example 26 except that instead of
24 parts of methyltrimethoxysilane, 48 parts of
isobutyltrimethoxysilane was mixed with 24 parts of
phenyltrimethoxysilane while stirring.
[0254] Similar results will be obtained when the procedure of
Example 26 is followed. Further improvements in flow and clarity
are obtained by adding 8 parts glycidyloxypropyltrimethoxysilane
with the other organosilane compounds.
[0255] Similar results will also be obtained when any of the
compositions of this Example or Example 26 are applied to metal
substrates.
EXAMPLE 32
[0256] This example demonstrates the feasibility of amine
catalyzation without acid stabilization, cf. Example 1.
[0257] Twenty parts of isopropyl alcohol are added to a pot
followed by 15 parts of methytrimethoxysilane and 5 parts of
propyltrimethoxysilane. While stirring, 0.9 part of
bis(trimethoxysilylpropyl)amine is added. Then, 6 parts of water
are added. After reacting for about 4 hours the mixture may be
applied by dipping or spraying onto aluminum or other metal
substrate. The dipped and sprayed coatings become hard in about
three hours. The mixture will not set up.
EXAMPLE 33
[0258] This example demonstrates the feasibility of fusing a
fugitively functioning (i.e., gas generating, e.g., H.sub.2 S)
catalyst to generate a coating from the invention silane coating
composition.
[0259] 20 parts of isopropyl alcohol are added to a pot, followed
by 15 parts of methyltrimethoxysilane and 5 parts of
propyltrimethoxysilane. While stirring, 0.9 part of
mercaptopropyltrimethoxysilane is added followed by 6 parts water.
After reacting for about 4 hours the mixture may be applied by
dipping or spraying onto aluminum. The coating becomes hard in
about 4 hours after application.
[0260] In this example, an intermediate silyl moiety, capable of
promoting hydrolysis and slow polymerization, is created. As
another example of fugitively functioning catalyst, a
disilylsilazane, such as hexamethyldisilazane (an ammonia
generator), heptamethyl disilazane, and the like, may be
mentioned.
EXAMPLE 34
[0261] This example shows a three part formulation (3-container
formulation) which provides extremely stable coatings.
[0262] 200 parts methyltrimethoxysilane and 100 parts isopropyl
alcohol are mixed in a first container (Container A). Separately,
in Container B, 40 parts of a saturated solution of calcium
hydroxide is diluted with 20 parts of water before the diluted
solution is added to Container A.
[0263] In Container C, 6.2 parts boric acid is dissolved in 96.8
parts of isopropyl alcohol and is after cooling begins, is combined
with the contents of Container A (to which the contents of
Container B has been added).
[0264] After about three days, the resulting mixture forms a
sprayable or wipeable coating composition which may be applied to
virtually any metal to provide an extremely corrosion- resistant,
heat-resistant finish. This coating composition may be used, for
example, on inside surfaces of food and beverage containers; on
exterior and interior building materials, such as ceramic roofing
tiles, concrete, galvanized steel, interior duct works, and the
like, to protect against deposition and growth of mildew or other
infectious organisms; overcoating of coated or uncoated concrete
and metallic surfaces to protect against and facilitate removal of
graffiti; overcoating to protect automotive, truck (inclusive of
cement and other construction trucks), buses and other vehicle
finishes; high temperature applications, such as, for example,
manifolds, exhaust systems, cooking utensils, ovens, and the like;
corrosion protection and/or deicing agent (in combination with a
primer, e.g., Example 30, of this invention); and gel-coat
maintenance finish.
EXAMPLE 35
[0265] 20 parts each of methyltrimethoxysilane and isopropyl
alcohol are mixed in a first container, Container A. Then, 0.3 part
of boric acid is added, followed by addition of 0.2 to 0.3 part of
tetrabutyl titanate to assist in the solubilization of the boric
acid catalyst. Finally, 10 to 20 parts of water are added slowly,
since the reaction is exothermic. After a few minutes, the mixture
will warm up and may be applied to a metallic or non-metallic
substrates. The mode of application is not particularly limited and
spraying, wiping, brushing, and the like may be mentioned as
suitable techniques.
EXAMPLE 36
[0266] As a further indication of the excellent corrosion
resistance and adhesion of the primers of the present invention,
one-half inch thick steel panels, which are first degreased and
sand blasted, are primed with the primer composition prepared
according to the above Example 30. To the cured dried primer
coating, a topcoat of Navy Standard epoxy deck coating is applied
and allowed to cure.
[0267] Each of the so prepared panels is subjected to an ASTM pull
test. Whereas primers currently in use fail this test at only
300-320 psi, the primer of this invention is able to withstand more
than 600 psi, without failing, and generally, about to about
700-720 psi, before failing.
EXAMPLE 37
[0268] In this example, the primer of Example 30, is used to prime
a steel panel for an automobile. A standard automobile finish is
applied to aluminum panels primed with the composition of the
present invention. The primed panels are able to withstand at least
30 or more flexures of about 120.degree. before the applied finish
(paint) flexes free at the bend. However, when the so treated
flexed panel is subjected to salt spray for three weeks no
corrosion is observed on the underlying aluminum panels, indicated
that the primer remains in contact with the panel without
separation.
EXAMPLE 38
[0269] This example illustrates the application of the coating
composition of the present invention to vinyl and asphalt tiles.
For this application, a vinyl group containing silane will be used
in the invention coating compositions.
[0270] To the composition of Example 4, 0.7%, based on the weight
of the silanes, of 3-methacryloxypropyltrimethoxysilane is added.
The resulting coating may be applied to the exposed tile surface by
brushing, or spraying, to a thickness of not more than about 1 mil.
The resulting coating provides a mildew resistant tile. Similar
results will be obtained by using the vinyl silane compound in an
amount of from about 0.5 to 1%, based on the weight of the silanes.
Similar results will also be obtained by using as the vinyl silane,
3-acryloxypropyltrimethyloxysil- ane, vinyltriethoxysilane or
vinyltrimethoxysilane. Similar results are also be obtained by
adding the vinyl silane to the composition of Examples 5-8.
EXAMPLE 39
[0271] To render a surface resistant to marring by graffiti, the
resulting coating should be resistant to ultraviolet (UV) light
exposure (e.g., sunlight), and be able to withstand repeated
washings, often as frequently as daily washings. This latter
property may be achieved by a high gloss coating to provide the
surface stable to repeated solvent application.
[0272] Generally, therefore, to facilitate on site application to
an existing wall surface, for example, the coating composition
should be applied after preliminary reaction to increase the
viscosity and provide a non-sacrificial coating. Therefore, the
preferred coating compositions according to this invention, for
providing an "anti-graffiti" coating, will be able to provide an
exothermic reaction capable of raising the temperature by at least
about 70.degree. C. in a gallon sized container. One suitable
composition for this purpose, therefore, comprises an acid or
titanium alcoholate-boric acid containing composition with a
mixture of phenyltrimethoxysilane and methyltrimethoxysilane, such
as the composition according to Example 2, which, when
hydrolyzed-polymerized, with shaking, provides the desired
temperature increase. Since the compositions are generally applied
while still warm, it is preferred to use an inert gas (e.g.,
nitrogen) propellant to slow solvent evaporation. Coatings
according to the present invention are able to withstand upwards of
100 or more solvent cleaning procedures without degradation.
EXAMPLE 40
[0273] This example illustrates the application of the compositions
according to the present invention which are required to withstand
exposure to high temperature, such as, for example, manifolds,
ovens, and the like. As was the case for the application to
"anti-graffiti" coatings in Example 39, the compositions for high
temperature applications should preferably also undergo a
substantial temperature increase, usually at least about 70.degree.
C. or more (for a gallon size batch). Alternatively, compositions
which cure under ambient conditions over a period of about one week
or longer, may be used.
[0274] In this regard, as the content of the silane oligomers in
the composition decrease, the temperature stability will
correspondingly increase.
[0275] A primer composition as described in Example 30 is prepared
and, after the temperature thereof has increased by about
70.degree. C. over ambient, is applied to an aluminum substrate. An
overcoat of an acid free coating material is then applied. The
aluminum may be subjected to high temperature above the melting
point of aluminum to generate a red heat until the overcoat becomes
fully tack free.
* * * * *