Note: Descriptions are shown in the official language in which they were submitted.
WO 95/27760 PCT/US95/02721
218371
$ The present invention relates to coating compositions
based on polyepoxides cured with polyacids and on the use of
compositions in color-plus-clear coating systems.
Original equipment finish coating systems for automobiles
have utilized color-plus-clear technology for a number of years.
This technology involves the application of a pigmented or otherwise
colored base coat to a substrate, followed by the application of a
transparent or clear topcoat to the basecoat. The clearcoat imparts
high gloss and distinctness of image to the system as well as
protecting the basecoat from environmental attack.
In more recent years, such original equipment finish
coatings have been required to demonstrate resistance to etching of
the finished surface by atmospheric acid precipitation, otherwise
referred to as acid-etch resistance. To address this requirement,
original equipment finish coating systems based on polyepoxides cured
2~ with polyacids have been developed which meet or exceed the acid-etch
resistance requirements of automotive manufacturers.
In addition to the requirement of acid-etch resistance,
original equipment finish coatings must also demonstrate resistance
to mar and scratching. The polyepoxide polyacid based coating
2S systems, while possessing good acid-etch resistance, have not
provided adequate mar resistance. While microparticulate materials
such as silica, metal sulfides, or crosslinked styrene-butadiene have
been added to such coatings, to improve mar resistance, these
materials typically adversely affect gloss and distinctness of image
3~ (DOI) of the coating due to the scattering of light at the particle
interfaces. Thus their effectiveness has been limited. It would be
thus desirable to have an original equipment finish automotive color-
plus-clear polyepoxide polyacid based coating system which could
provide good mar resistance while maintaining excellent acid-etch
35 resistance, gloss and DOI.
WO 95127760
PCT/ITS95/02721
2
S RY OF THE INVENTInN
In accordance with the present invention, there is
provided a mar and acid-etch resistant film forming composition,
comprising a polyepoxide which is essentially free of silyl moieties,
S a polyacid curing agent, and an additive amount effective to improve
mar resistance of a solution polymer of an ethylenically unsaturated
monomer component comprising a polymerizable alkoxy silane monomer.
Also provided in accordance with the present invention is
a method of applying a coating composition to a substrate comprising
1~ applying to the substrate a pigmented film-forming composition to
form a basecoat and applying to said basecoat as a topcoat a clear
mar and acid-etch resistant film-forming composition according to the
present invention.
IS DETAINED DESCRIP'~'rnN OF THE INVENTION
The film forming composition of the present invention is based
on a polyepoxide polymer and a polyacid curing agent. The
polyepoxide polymer is essentially free of silyl moieties; that is
0 the polyepoxide polymer contains no more than about 1 percent,
preferably no more than about 0.1 percent of silicon, the percentage
based on the total weight of the polyepoxide polymer. The film
forming composition also contains a solution polymer synthesized from
an ethylenically unsaturated monomer component comprising a
25 polymerizable ethylenically unsaturated alkoxy silane monomer.
Preferably the ethylenically unsaturated monomer component
. additionally contains at least one other polymerizable ethylenically
unsaturated monomer. The claimed film forming compositions are
particularly advantageous in exhibiting improved mar resistance in
~ conjunction with good acid etch resistance and overall appearance of
the cured film.
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The amount of polymerizable alkoxy silane monomer present
in the monomer component ranges from about 60 to about 100,
preferably from about 60 to about 80 percent by weight, the
percentages based on total weight of the monomers present in the
monomer component. Suitable polymerizable alkoxy silane monomers
include those represented by the following structures I and II:
R3 O R
CH2 =C-COCF~2- (CH2) n-CH2-Si-OR1
OR2
(I)
IS
where R is CH3, CHgCH2, CH30, or CH3CH20; R1 and Ra independently are
CH3 or CH3CH2; R3 is H, CH3, or CH3CH2; and n is 0 or a positive
integer from 1 to 10. Preferably, R is CH30 or CH3CH20 and n is 1.
R
CH2=CH-Si-OR1
OR2
(III
where R, R1 and R2 are as described above.
Typical examples of alkoxy silane monomers with structure
(I) include acrylatoalkoxy silanes, such as gamma-
acryloxypropyltrimethoxy silane, and the methacrylatoalkoxy silanes,
such as gamma-methacryloxypropyltrimethoxy silane and gamma-
methacryloxypropyltris(2-methoxyethoxy)silane.
Examples of alkoxy silane monomers with structure (II)
are the vinylalkoxy silanes, such as vinyl trimethoxy silane, vinyl
triethoxy silane and vinyl tris(2-methoxyethoxy)silane.
Further suitable alkoxy silane monomers include
ethylenically unsaturated acrylcxysilanes, such as acrylatoxy silane
and methacrylatoxy silane, vinylacetoxy silanes, such as vinylmethyl
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4
diacetoxy silane, acrylatopropyltriacetoxy silane, and
methacrylatopropyltriacetoxy silane, or any mixture of the above
alkoxy silane monomers. Preferably the alkoxy silane monomer is
gamma-methacryloxypropyltrimethoxysilane.
The other polymerizable ethylenically unsaturated monomer
is present in the ethylenically unsaturated monomer component in an
amount generally ranging from about 0 to about 40 percent, preferably
from about 20 to about 40 percent by weight, the percentages based on
the total weight of thermonomers present in the ethylenically
unsaturated monomer component. Examples of suitable polymerizable
ethylenically_unsaturated monomers include alkylacrylates and
alkylmethacrylates having from 1 to 20 carbon atoms in the alkyl
group such as methyl acrylate, methyl methacrylate, ethyl acrylate,
n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, isobutyl
methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate; vinyl
aromatic monomers such as styrene, alpha-methyl styrene, and vinyl
toluene; nitrile monomers such as acrylonitrile and
methacrylonitrile. Preferably the other ethylenically unsaturated
monomer is n-butyl methacrylate.
The solution polymer is synthesized utilizing standard
free radical initiated solution polymerization techniques well known
to those skilled in the art of polymer chemistry. Generally the
polymerization is conducted in a high boiling solvent such as
Solvesso -100 (aromatic hydrocarbon, commercially available from
Exxon Chemical Company) under nitrogen or similar inert atmosphere to
maintain a moisture free environment. The polymerization is
generally conducted at reflex temperature for a period ranging from
about 1 to 10 hours, preferably from about 5 to 8 hours. Suitable
free radical initiators include organic peroxides such as di-tert-
~ butylperoxide, benzoyl peroxide, and dicumene peroxide; and azo
compounds such as 2,2'-azobis(2-methylbutane nitrile). The amount of
free radical initiator can vary depending upon the particular
reaction conditions but typically from about 3 percent to about 8
percent, based on total weight of the monomers present, is used. The
reaction is considered complete when the total free monomer
CA 02187371 2000-04-11
concentration is lese~ than about 2 percent by weight, the percentage
based on the total weight of the reaction mixture.
The solution polymer is used in the film forming
composition in an amount effective to improve mar resistance while
5 maintaining acid-etch resistance, gloss and DOI. Typically, the
amount will vary from about 1 to about 20 percent, preferably from
about 10 to about 20, percent by weight, the percentage based on the
total weight of the resin solids of the composition. The solution
polymer generally ha:~ a number average molecular weight ranging from
about 500 to about 20,000, preferably from about 1200 to about 500p,
as determined by gel permeation chromatography (GPC) using
polystyrene standards.
The mar and acid-etch resistant film forming
composition which contains the solution polymer is preferably a
clear film forming composition which is used to form a transparent
topcoat over a pigmented basecoat. As mentioned above, the clear
film-forming composition according to the present invention
comprises as a film :=ormer a polyepoxide resin which is essentially
free of silyl moieties and a polyacid curing agent which preferably
comprises a half-ester formed from reacting an acid anhydride with a
polyol.
The polvepoxides which can be used include epoxy-
containing acrylic polymers, epoxy condensation polymers such as
polyglycidyl ethers of alcohols and phenols, polyglycidyl esters of
polycarboxylic acids, and mixtures of the foregoing. By essentially
free of silyl moieties is meant that the polyepoxide polymer
contains no more than about 1 percent silicon, preferably less than
about 0.1 percent silicon, the percentage based on the total weight
of the polyepoxide polymer.
WO 95/27760
PCT/US95/02721
6
A suitable epoxy-containing acrylic polymer is a
copolymer of an ethylenically unsaturated monomer having at least one
epoxy group and at least one polymerizable ethylenically unsaturated
monomer which is free of epoxy groups.
Examples of ethylenically unsaturated monomers containing
epoxy groups are those containing 1,2-epoxy groups and include
glycidyl acrylate, glycidyl methacrylate and allyl glycidyl ether.
Examples of ethylenically unsaturated monomers which do
not contain epoxy groups are alkyl esters of acrylic and methacrylic
1~ acid containing from 1 to 20 carbon atoms in the alkyl group.
Specific examples of these acrylates and methacrylates include methyl
acrylate, methyl methacrylate, ethyl methacrylate, n-butyl
methacrylate, ethyl acrylate, n-butyl acrylate and 2-ethylhexyl
acrylate. Examples of other copolymerizable ethylenically
15 unsaturated monomers are vinyl aromatic compounds such as styrene,
alpha-methyl styrene, and vinyl toluene; nitriles such as
acrylonitrile and methacrylonitrile; vinyl and vinylidene halides
such as vinyl chloride and vinylidene fluoride and vinyl esters such
as vinyl acetate.
The epoxy group-containing ethylenically unsaturated
monomer is preferably used in amounts of from about 5 to about 90,
more preferably from about 20 to about 70 percent by weight of the
total monomers used in preparing the epoxy-containing acrylic
polymer. Of the remaining polymerizable ethylenically unsaturated
25 monomers, preferably from about 10 to about 95 percent, more
preferably from about 30 to about 80 percent by weight of the total
monomers are the alkyl esters of acrylic and methacrylic acid.
The epoxy containing acrylic polymer can be prepared by
well known free radical initiated solution polymerization techniques
3~ in the presence of suitable free radical initiators such as organic
peroxides, such as t-butyl perbenzoate, t-amyl peracetate or ethyl-
3,3-di(t-amylperoxy)butyrate or azo compounds, such as 2,2'-azobis(2-
methylbutane nitrile) and 2,2'-azobis(2-methylpropane nitrile). The
polymerization is typically carried out in an organic solvent in
35 which the monomers and the polymer are soluble. Suitable solvents
are aromatic solvents such as xylene and toluene, ketones such as
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7
methyl amyl ketone or ester solvents such as ethyl 3-
ethoxypropionate.
Suitable epoxy condensation polymers include polyepoxides
having a 1,2-epoxy equivalency greater than 1, preferably greater
5 than 1 and up to about 5Ø Useful examples of such polyepoxides are
polyglycidyl esters from the reaction of polycarboxylic acids with
epihalohydrins such as epichlorohydrin. The polycarboxylic acid can
be formed by any method known in the art and in particular, by the
reaction of aliphatic alcohols with an anhydride, and in particular,
10 diols and higher functionality alcohols. For example, trimethylol
propane or pentaerythritol can be reacted with hexahydrophthalic
anhydride to produce a polycarboxylic acid which is then reacted with
epichlorohydrin to produce a polyglycidyl ester. Additionally, the
polycarboxylic acid can be an acid-functional acrylic polymer.
15 Further examples of such epoxides are polyglycidyl ethers
of polyhydric phenols and of aliphatic alcohols. These polyepoxides
can be produced by etherification of the polyhydric phenol or
aliphatic alcohol with an epihalohydrin such as epichlorohydrin in
the presence of alkali.
20 Examples of suitable polyhydric phenols are 2,2-bis(4-
hydroxyphenyl)propane (bisphenol A) and l,l-bis(4-
hydroxyphenyl)ethane. Examples of suitable aliphatic alcohols are
ethylene glycol, diethylene glycol, pentaerythritol, trimethylol
propane, 1,2-propylene glycol and 1,4-butylene glycol. Also,
25 cycloaliphatic polyols such as 1,2-cyclohexanediol, 1,4-
cyclohexanediol, 1,4 cyclohexane dimethanol, 1,2-
bis(hydroxymethyl)cyclohexane and hydrogenated bisphenol A can also
be used.
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Besides the polyepoxides described above, certain
polyepoxide monomers and oligomers can also be used. Examples of
these materials are described in U.S. Patent No. 4,102,942 in column
3, lines 1-16. Specific
S examples of such low molecular weight polyepoxides are 3,4-
epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate and bis(3,4-
epoxycyclohexylmethyl) adipate. These materials are aliphatic
polyepoxides as are the epoxy-containing acrylic polymers described
above. As mentioned above, the epoxy-containing acrylic polymers are
preferred because they result in products which have the optimum
combination of coating properties, i.e., smoothness, gloss,
durability and solvent resistance. Such polymers have been found to
be particularly useful in the formulation of clear coats for color-
plus-clear applications. Of course, as mentioned above, mixtures of
these polyepoxides can be used.
The polyepoxide is present in the film-forming
composition in amounts of from about l0 percent by weight to about 90
percent by weight, preferably from about 20 percent by weight to
about 80 percent by weight and more preferably from about 40 percent
by weight to about 70 percent by weight, the percentage based on
total weight of resin solids.
The polyacid curing agent contains two or more acid
groups per molecule which are reactive with the polyepoxide to form a
crosslinked coating film as indicated by the film's resistance to
organic solvent. The polyacid curing agent preferably comprises a
half-ester formed from reacting an acid anhydride with a polyol. The
acid functionality is preferably carboxylic acid, although acids such
as sulfonic acid may be used but their use is not preferred. The
half-esters are relatively low in molecular weight and quite reactive
with epoxies enabling the formation of high solids fluid compositions
while maintaining outstanding properties such as gloss and
distinctness of image.
WO 95/27760 218 7 3 71 pCTIUS95/02721
9
The half-ester is obtained by reaction between a polyol
and a 1,2-acid anhydride under conditions sufficient to open the
anhydride ring forming the half-ester with substantially no
polyesterification occurring. Such reaction products are of
$ relatively low molecular weight with narrow molecular weight
distributions and low viscosity and provide lower volatile organic
contents in the coating composition while still providing for
excellent properties in the resultant coating. By substantially no
polyesterification occurring means that the carboxyl groups formed by
the reaction of the anhydride are not further esterified by the
polyol in a recurring manner. By this is meant that less than about
10, preferably less than about 5 percent by weight high molecular
weight polyester is formed.
Two reactions may occur in combining the anhydride and
the polyol together under suitable reaction conditions. The desired
reaction mode involves ring opening the anhydride ring with hydroxyl,
i.e.,
X-(-O-C-R-C-OH)A
II II
0 0
where X is the residue of the polyol after the polyol has been
reacted with a 1,2-dicarboxylic acid anhydride, R is an organic
2S moiety from the anhydride and A is an integer equal to at least 2.
Subsequently, carboxylic acid groups formed by opening of
the anhydride ring may react with hydroxyl groups to give off water
via a condensation reaction. This latter reaction is not desired
since it can lead to a polycondensation reaction resulting in
products with higher molecular weights.
To achieve the desired reaction, the 1,2-acid anhydride
and polyol are contacted together usually by mixing the two
ingredients together in a reaction vessel, preferably in the presence
of an inert atmosphere such as nitrogen and in the presence of a
solvent to dissolve the solid ingredients and/or to lower the
viscosity of the reaction mixture. Examples of suitable solvents are
high boiling materials and include, for example, ketones such as
WO 95/27760 ~ ~ ~ PCT/US95102721
io
methyl amyl ketone, diisobutyl ketone, methyl isobutyl ketone;
aromatic hydrocarbons such as toluene and xylene; as well as other
organic solvents such as dimethyl formamide and N-methyl-pyrrolidone.
For the desired ring opening reaction and half-ester
formation, a 1,2-dicarboxylic anhydride is used. Reaction of a
polyol with a carboxylic acid instead of an anhydride would require
esterification by condensation with elimination of water which would
have to be removed by distillation. Under these conditions this
would promote undesired polyesterification. Also, the reaction
1~ temperature is preferably low, that is, no greater than about 135°C,
preferably less than about 120°C, and usually within the range of
about 70° to about 135°C, preferably about 90° to about
120°C.
Temperatures greater than 135°C are undesirable because they
promote
polyesterification, whereas temperatures less than 70°C are
1S undesirable because of sluggish reaction rates.
The time of reaction can vary somewhat depending
principally upon the temperature of reaction. Usually the reaction
time will vary from about 10 minutes to about 24 hours.
The equivalent ratio of anhydride to hydroxyl on the
20 polyol is preferably at least about 0.8:1 (the anhydride being
considered monofunctional) to obtain maximum conversion to the
desired half-ester. Ratios less than 0.8:1 can be used but such
ratios result in increased formation of lower functionality half-
esters.
25 Among the anhydrides which can be used in formation of
the desired polyesters are those which, exclusive of the carbon atoms
on the anhydride moiety, contain from about 2 to 30 carbon atoms.
Examples include aliphatic, including cycloaliphatic, olefinic and
cycloolefinic anhydrides and aromatic anhydrides. Substituted
~ aliphatic and aromatic anhydrides are also included within the
definition of aliphatic and aromatic provided the substituents do not
adversely affect the reactivity of the anhydride or the properties of
the resultant polyester. Examples of substituents would be chloro, '
alkyl and alkoxy. Examples of anhydrides include succinic anhydride,
35 methylsuccinic anhydride, dodecenyl succinic anhydride,
octadecenylsuccinic anhydride, phthalic anhydride, tetrahydrophthalic
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il
anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic
anhydride, alkyl hexahydrophthalic anhydrides such as
methylhexahydrophthalic anhydride, tetrachlorophthalic anhydride,
endomethylene tetrahydrophthalic anhydride, chlorendic anhydride,
itaconic anhydride, citraconic anhydride and malefic anhydride.
Among the polyols which can be used are simple polyols,
that is, those containing from about 2 to 20 carbon atoms, as well as
oligomeric polyols and polymeric polyols such as polyester polyols,
polyurethane polyols and acrylic polyols.
Among the simple polyols are diols, triols, tetrols and
mixtures thereof. Examples of the polyols are preferably those
containing from 2 to 10 carbon atoms such as aliphatic polyols.
Specific examples include but are not limited to the following
compositions: di-trimethylol propane(bis(2,2-
dimethylol)dibutylether); pentaerythritol; 1,2,3,4-butanetetrol;
sorbitol; trimethylol propane (TMP); trimethylol ethane; 1,2,6-
hexanetriol; 1,3,6-hexanetriol: glycerine; trishydroxyethyl
isocyanurate: dimethylol propionic acid: 1,2,4-butanetriol;
1,3,4-butanetriol; TMP/epsilon-caprolactone triols; ethylene
glycol; 1,2-propanediol; 1,3-propanediol; 1,4-butanediol;
1,5-pentanediol; 1,6-hexanediol: neopentyl glycol; diethylene
glycol: dipropylene glycol: 1,4-cyclohexanedimethanol and
2,2,4-trimethylpentane-1,3 diol.
Suitable oligomeric polyols, include polyols made from
reaction of diacids with triols, such as trimethylol
propane/cyclohexane diacid and trimethylol propane/adipic acid.
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With regard to polymeric polyols, the polyester polyols
are prepared by esterification of an organic polycarboxylic acid or
anhydride thereof with organic polyols and/or an epoxide. Usually,
the polycarboxylic acids and polyols are aliphatic or aromatic
dibasic acids or acid anhydrides and diols.
The polyols which are usually employed in making the
polyester include trimethylol propane, di-trimethylol propane,
alkylene glycols such as ethylene glycol, neopentyl glycol and other
glycols such as hydrogenated bisphenol A, cyclohexanediol,
cyclohexanedimethanol, the reaction products of lactones and diols,
for example, the reaction product of epsilon-caprolactone and
ethylene glycol, hydroxy-alkylated bisphenols, polyester glycols, for
example, poly(oxytetramethylene)glycol and the like.
The acid component of the polyester consists primarily of
monomeric carboxylic acids or anhydrides having 2 to 18 carbon atoms
per molecule. Among the acids which are useful are phthalic acid,
isophthalic acid, terephthalic acid, tetrahydrophthalic acid,
hexahydrophthalic acid, methylhexahydrophthalic acid, adipic acid,
azelaic acid, sebacic acid, malefic acid, glutaric acid, chlorendic
acid, tetrachlorophthalic acid and other dicarboxylic acids of
varying types. Also, there may be employed higher polycarboxylic
acids such as trimellitic acid and tricarballylic acid. However, the
use of these higher functionality polycarboxylic acids are not
preferred because of resultant high viscosities.
Besides the polyester polyols formed from polybasic acids
and polyols, polylactone-type polyesters can also be employed. These
products are formed from the reaction of a lactone such as epsilon-
caprolactone and a polyol such as ethylene glycol, diethylene glycol
and trimethylolpropane.
Besides polyester polyols, polyurethane polyols such as
polyester-urethane polyols which are formed from reacting an organic
polyisocyanate with a polyester polyol such as those described above
can be used. The organic polyisocyanate is reacted with a polyol so
that the OH/NCO equivalent ratio is greater than 1:1 so that the
resultant product contains free hydroxyl groups. The organic
polyisocyanate which is used in preparing the polyurethane polyols
WO 95127760 PCT/US95102?21
2187371
13
can be an aliphatic or aromatic polyisocyanate or a mixture.
Diisocyanates are preferred, although higher polyisocyanates such as
triisocyanates can be used, but they do result in higher viscosities.
Examples of suitable diisocyanates are 4,4~-
diphenylmethane diisocyanate, 1,4-tetramethylene diisocyanate,
isophorone diisocyanate and 4,4~-methylenebis(cyclohexyl isocyanate).
Examples of suitable higher functionality polyisocyanates are
polymethylene polyphenol isocyanates.
It is also possible to use as the polyacid curing agent
l~ acid-functional acrylic crosslinkers made from copolymerizing
methacrylic acid and/or acrylic acid monomers with other
ethylenically unsaturated copolymerizable monomers. Alternatively,
acid-functional acrylic crosslinkers can be prepared from hydroxy-
functional acrylic monomers reacted with cyclic anhydrides.
The polyacid curing agent is present in the film forming
composition in amounts of from about 10 to about 90, preferably about
to about 75 percent by weight, the percentages based on total
weight of resin solids.
Optional film forming materials which are preferably
2~ added to the claimed compositions include an acid functional acrylic
polymer and an anhydride.
The acid functional acrylic polymers are reaction
products of an ethylenically unsaturated polymerizable carboxylic
acid such as acrylic acid or methacrylic acid with another
25 ethylenically unsaturated polymerizable monomer different from said
acids. These products are non-gelled and typically will have number
average molecular weights as determined by gel permeation
chromatography, using polystyrene standards, of from about 500 to
about 5000, preferably about 700 to about 3000.
WO 95127760 ~ ~ ~ PCT/US95102721
14
The amount of acid functional acrylic polymer which is
used can vary from 0 to about 50, preferably from about 10 to about
20 percent by weight based on total weight of resin solids.
The polyepoxide-polyacid compositions also preferably
contain an anhydride, preferably an anhydride which is a liquid at 25
°C. The presence of such an anhydride in the compositions provides
an improved cure response. Examples of suitable anhydrides include
alkyl-substituted hexahydrophthalic anhydrides such as methyl
hexahydrophthalic anhydride and dodecenyl succinic anhydride. The
1~ amount of the anhydride which is used can vary from 0 to about 40,
preferably from about 5 to about 25 percent by weight based on total
weight of resin solids.
The equivalent ratio of carboxylic acid in the polyacid
curing agent to epoxy in the polyepoxide in the clear film-forming
compositions can vary depending upon the particular curing
conditions. For example, at higher temperatures a lower equivalent
ratio can be used whereas at lower temperatures a higher equivalent
ratio is more suitable. Preferably the ratio is adjusted so that
there are about 0.3 to about 3.0, preferably about 0.8 to about 1.5
2~ equivalents of carboxyl (anhydride being considered monofunctional)
per equivalent of epoxy, that is the equivalent ratio of acid to
epoxy ranges from about 0.3:1 to about 3.0:1, preferably from about
0.8:1 to about 1.5:1.
The compositions will also preferably contain catalysts
to accelerate the cure of the epoxy and acid groups. Examples of
suitable catalysts include organic amines and quaternary ammonium
. compounds such as pyridine, piperidine, dimethylaniline,
diethylenetriamine, tetramethylammonium chloride, tetramethylammonium
acetate, tetramethylbenzylammonium acetate, tetrabutylammonium
3~ fluoride, and tetrabutylammonium bromide. The amount of catalyst
typically ranges from 0 to about 10 percent, preferably from about
0.5 to about 3 percent by weight based on resin solids.
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The polyepoxide-polyacid clear film forming compositions
according to the present invention are preferably formulated into
high solids coating compositions. That is, these film forming
compositions contain greater than about 50 percent, most preferably
5 greater than about 60 percent by weight resin solids. The solids
content is determined by heating the composition to about 105°-
110° C
for 1 to 2 hours to drive off the volatile material. The film
forming compositions are preferably liquid high solids compositions
formulated as either one package or two package compositions. When
10 formulated as a two package composition, the ingredients, including
the alkoxy silane polymer, can be in either package as desired so
long as the polyepoxide film-former and polyacid curing agent are in
separate packages. Preferably the compositions are formulated as one
package compositions.
15 Also, optional ingredients such as auxiliary curing
agents such as aminoplast resins, plasticizers, anti-oxidants, and Uv
light absorbers can be included in the film forming composition.
These ingredients typically are present in amounts up to 30 percent
by weight based on total resin weight.
When utilizing the clear film forming compositions of the
present invention as a topcoat over a pigmented basecoat, in
preparing a composite coated substrate, the film-forming composition
of the basecoat can be any of the compositions useful in coatings
applications, particularly automotive applications, including
thermoplastic and thermosetting (crosslinking) coating compositions.
The pigmented film-forming composition typically comprises a resinous
. binder and a pigment. Particularly useful resinous binders are
resinous binders known in the art of polymer chemistry such as
acrylic polymers, polyester polymers, including alkyds, and
polyurethane polymers.
The acrylic polymers are typically copolymers of one or
more alkyl esters of acrylic acid or methacrylic acid having from 1
to 20 carbon atoms in the alkyl group optionally together with one or
more other polymerizable ethylenically unsaturated monomers. These
polymers can be either thermoplastic or thermosetting. Suitable
alkyl esters of acrylic acid or methacrylic acid include methyl
CA 02187371 1999-07-20
WO 95/27760 PCT/US95/02721
16
methacrylate, isobutyl methacrylate, alpha-methyl styrene dimer,
ethyl methacrylate, n-butyl methacrylate, ethyl acrylate, n-butyl
acrylate, 2-ethylhexyl acrylate, and 2-ethylhexyl methacrylate.
Suitable other copolymerizable ethylenically unsaturated monomers
S include vinyl aromatic compounds such as styrene and vinyl toluene;
nitriles such as acrylonitrile and methacrylonitrile; vinyl and
vinylidene halides such as vinyl chloride and vinylidene fluoride and
vinyl esters such as vinyl acetate.
When the acrylic polymer is of the crosslinking type,
suitable active hydrogen functional monomers are used in addition to
the other acrylic monomers mentioned above and include, for example,
acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxyethyl
methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate.
The coating composition in such cases contains a crosslinking agent
1S capable of reacting with the active hydrogen groups contributed to
the polymer by the functional monomers such as aminoplast resins
which include condensates of an amine or an amide with such as urea,
melamine, or benzoguanamine reacted with formaldehyde or a lower
alkyl ether of such condensate in which the alkyl groups contain from
2~ 1 to 4 carbon atoms. Other crosslinking agents such as
polyisocyanates including blocked polyisocyanates can also be used.
Also, the acrylic polymer can be prepared with N-
(alkoxymethyl)acrylamide monomers) and N-
(alkoxymethyl)methacrylamide monomers) which result in an acrylic
25 polymer capable of self crosslinking without the presence of
crosslinking agents such as those described above.
The acrylic polymer can be prepared by free radical
initiated solution polymerization techniques in the presence of
suitable free radical initiators such as organic peroxides or azo
30 compounds, for example, benzoyl peroxide or 2,2~-azobis(2-
methylbutane nitrile). The polymerization can be carried out in an
organic solvent in which the monomers and resultant polymer are
soluble. Suitable solvents include aromatic solvents such as xylene
and toluene and ketones such as methyl amyl ketone. Alternately, the
35 acrylic polymer can be prepared by aqueous emulsion or dispersion
polymerization techniques well known to those skilled in the art.
CA 02187371 1999-07-20
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17
Besides acrylic polymers, the resinous binder for the
basecoat composition can be a polyester polymer (including alkyds).
Such polymers may be prepared in a known manner by condensation of
polyhydric alcohols and polycarboxylic acids. Suitable polyhydric
alcohols include ethylene glycol, propylene glycol, butylene glycol,
1,6-hexylene glycol, neopentyl glycol, diethylene glycol, glycerol,
trimethylolpropane, and pentaerythritol.
Suitable polycarboxylic acids include succinic acid,
adipic acid, azelaic acid, sebacic acid, malefic acid, fumaric acid,
phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, and
trimellitic acid. Besides the polycarboxylic acids mentioned above,
functional equivalents of the polycarboxylic acids such as anhydrides
where they exist or lower alkyl esters of the polycarboxylic acids
such as the methyl esters may be used.
Where it is desired to produce air-drying alkyd resins
from the polyester polymer, suitable drying oil fatty acids can be
used to modify the polyester by methods well known to those skilled
in the art, and include those derived from linseed oil, soya bean
oil, tall oil, dehydrated castor oil or tong oil.
The polyester polymers including the alk d
y polymers can
be thermoplastic or thermosetting. A thermosetting polyester
generally contains a portion of free hydroxyl and/or carboxyl groups
which are available for crosslinking reaction with a crosslinking
agent. Suitable crosslinking agents are the amine or amide-aldehyde
condensates or the polyisocyanate curing agents as mentioned above.
Polyurethanes can also be used as the resinous binder of
the basecoat. Among the polyurethanes which can be used are
polymeric polyols which are prepared by reacting the polyester
polyols or acrylic polyols such as those mentioned above with a
polyisocyanate such that the OH/NCO equivalent ratio is greater than
1:1 so that free hydroxyl groups are present in the product.
The organic polyisocyanate which is used to prepare the
polyurethane polyol can be an aliphatic or an aromatic polyisocyanate
or a mixture of the two. Diisocyanates are preferred, although
3$ higher polyisocyanates can be used in place of or in combination with
diisocyanates.
CA 02187371 1999-07-20
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WO 95/27760 PCT/US95/02721
18
Examples of suitable aromatic diisocyanates are 4,4'-
diphenylmethane diisocyanate and toluene diisocyanate. Examples of
suitable aliphatic diisocyanates are straight chain aliphatic
diisocyanates such as 1,6-hexamethylene diisocyanate. Also,
cycloaliphatic diisocyanates can be employed. Examples include
isophorone diisocyanate and 4,4'-methylene-bis(cyclohexyl
isocyanate). Examples of suitable higher polyisocyanates are 1,2,4-
benzene triisocyanate and polymethylene polyphenyl isocyanate.
The polymers prepared as described above are typically
organic solvent-based polymers, although as mentioned above acrylic
polymers can be prepared via aqueous emulsion polymerization
techniques and used as film forming binders for aqueous-based
basecoat compositions. Suitable aqueous-based basecoats for use in
color-plus-clear applications are disclosed in U.S. Patent No.
1S 4,403,003, and can be used
in the practice of this invention. Also, aqueous-based polyurethanes
such as those prepared in accordance with U.S. Patent No. 4,147,679,
can be used as the
resinous binder of the basecoat.
24 As mentioned above, the basecoat composition also
contains pigments to give it color. Compositions containing metallic
flake pigmentation are especially useful for the production of so-
called "glamour metallic" finishes chiefly upon the surface of
automobile bodies.v Proper orientation of the metallic pigments
2$ results in a lustrous shiny appearance with excellent flop,
distinctness of image and high gloss. By flop is meant the visual
change in brightness or lightness of the metallic coating with a
change in viewing angle, that is, a change from 90° to 180°. The
greater the change, that is, from light to dark appearance, the
~ better the flop. Flop is important because it accentuates the lines
of a curved surface such as on an automobile body. Suitable metallic
pigments include in particular aluminum flake, copper bronze flake
and mica.
Besides the metallic pigments, the basecoat compositions
3S of the present invention can contain non-metallic color pigments
conventionally used in coating compositions including inorganic
WO 95/27760 PCTIUS95102721
~1 X7371
19
pigments such as titanium dioxide, iron oxide, chromium oxide, lead
chromate and carbon black, and organic pigments such as
phthalocyanine blue and phthalocyanine green. In general, the total
amount of pigment incorporated into the coating composition is in
$ amounts of from about 1 to about 80 percent by weight based on weight
of the resin solids of the composition. The metallic pigment is
employed in amounts of about 0.5 to 25 percent by weight of the
aforesaid aggregate weight.
If desired, the basecoat composition can additionally
contain other materials well known in the art of formulated surface
coatings. These would include surfactants, flow control agents,
thixotropic agents, fillers, anti-gassing agents, organic co-
solvents, catalysts and other customary auxiliaries. These materials
can constitute up to 40 percent by weight of the total weight of the
1$ coating composition.
The basecoat compositions can be applied to various
substrates to which they adhere. The compositions can be applied by
conventional means including brushing, dipping, flow coating,
spraying and the like, but they are most often applied by spraying.
The usual spray techniques and equipment for air spraying and
electrostatic spraying and either manual or automatic methods can be
used.
Coatings of the present invention can
be applied over
virtually any substrate including wood, glass, cloth,
metals,
2$plastic, foam, including elastomeric , and the like.
substrates They
are particularly useful in applying overand elastomeric
metal
substrates that are found on motor vehicles.
During application of the basecoat composition to the
substrate, a film of the basecoat is the substrate.
formed on
30Typically, the basecoat thickness will 0.05 to 3, preferably
be about
0.1 to 2 mils in thickness.
After application to the substrate of the basecoat
composition, a film is formed on the the substrate. This
surface of
is achieved by driving solvent, i.e.,
organic solvent or water, out
3$of the basecoat film by heating or simplyair-drying period.
by an
Preferably, the heating step will only
be sufficient and for a short
WO 95/27760
PCTlUS95102721
period of time to insure that the topcoat composition can be applied
to the basecoat without the former dissolving the basecoat
composition, i.e., "striking in". Suitable drying conditions will
depend on the particular basecoat composition, on the ambient
5 humidity with certain waterbased compositions, but in general a
drying time of from about 1 to 5 minutes at a temperature of about 60
°-175°F (15°-79°C) will be adequate to insure that
mixing of the two
coats is minimized. At the same time, the basecoat film is
adequately wetted by the topcoat composition so that satisfactory
1~ intercoat adhesion is obtained. Also, more than one basecoat and
multiple topcoats may be applied to develop the optimum appearance.
Usually between coats, the previously applied basecoat or topcoat is
flashed, that is, exposed to ambient conditions for about 1 to about
20 minutes.
15 After application of a pigmented basecoat as described
above, a clear film forming composition of the present invention can
be applied to the basecoat by any of the conventional coating
techniques such as brushing, spraying, dipping or flow coating, but
it is preferred that spray applications be used since such
2~ applications give the optimum gloss. Any of the known spray
techniques can be employed, such as compressed air spraying,
electrostatic spraying and either manual or automatic methods. Prior
to application of a topcoat, it is possible to air flash the
basecoated substrate for a brief period of time, typically ranging
from about 1 to about 5 minutes. Optionally, the coated substrate
can be heat flashed between application of a base and topcoat.
After application of the clear topcoat composition to the
pigmented basecoat, the coated substrate is heated to cure the
coating layers. In the curing operation, solvents are driven off and
3~ the film-forming material of the topcoat and/or the basecoat is
cured. The heating or curing operation is usually carried out at a
temperature in the range of from about 250°F to about 400°F
(121°C to
205°C), and more preferably in the range of from about 260°F to
about
325°F (127°C to 162°C). Typically, the topcoat is applied
at a
3$ uniform film thickness usually ranging from about 0.5 to about 5 mils
and more preferably from about 1.2 to about 3 mils.
CA 02187371 2000-04-11
21
The invention will be further described by reference to
the following examples. Unless otherwise indicated, all parts are
by weight.
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22
E~LBMgLF~
The following examples A, B, and C show the preparation
of a solution polymer, polyepoxide resin, and polyacid curing agent
which are utilized in formulating the clear one package film-forming
compositions of examples 1 to 5.
$XAMPLB A
An alkoxy silane' olution polymer Was prepared from the
following mixture of ingredients:
InQred~ents
W Zght in ama
Initial Charge
SOLVESSO~-1001
1,634.6
Feed 1
Gamma-methacryloxypropyltrimethoxy silane 4,363.8
n-Butyl methacrylate 1,091.0
Feed 2
SOLVESSO-100 109.2
Feed 3
Di-tert-butylperoxide 272.8
SOLVESSO-100 545.6
Feed 4
SOLVESSO-100 54.6
Feed 5
Di-tert-butylperoxide 54.4
SOLVESSO-100 109.2
Feed 6
SOLVESSO-100 54.6
1 Aromatic hydrocarbon, commercially available from Exxon Chemical
Company
The initial charge was heated under, nitrogen in a reaction
vessel with agitation to reflux temperature (155°C). Feeds 1 and 3
were initiated simultaneously and continued in a substantially
continuous manner over a period of 3 hours while maintaining the
reaction mixture at reflux temperature. At the completion of Feeds 1
and 3, the addition funnels were rinsed with Feeds 2 and 4, and the
reaction mixture was held for 1 hour at reflwc temperature. Then
Feed 5 was added over 30 minutes and the addition funnel was rinsed
with Feed 6. The reaction mixture was held for 2 hours at reflux
temperature to complete the polymerization. The reaction mixture was
* Trade-mark
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23
cooled and filtered. The resultant solution polymer had a total
solids content of 69.1 percent determined at 110°C for one hour, and
a number average molecular weight of 2405 as determined by gel
permeation chromatography (GPC) using polystyrene standards. The
Gardner-Holdt viscosity was D+.
EXAMPLE B
An epoxy containing acrylic polymer was prepared from the
. following mixture of ingredients:
Incrredi ents w ;,ght ~ ,n g
Charge 1
Xylene 186.1
Ethyl 3-ethoxypropionatel 572.9
Charge 2
Glycidyl methacrylate 1200.0
Methyl methacrylate 11.7
n-Butyl methacrylate 350.1
Styrene 81.7
Alpha-methyl styrene dimer 23.2
Ethyl 3-ethoxypropionate 10.0
Charge 3
LUPERSOL'555-M602 200.0
Ethyl 3-ethoxypropionate
110.0
Charge 4
2S Methyl methacrylate g_3
n-Butyl methacrylate 250.1
Styrene 58.3
Alpha-methyl styrene dimer 16.6
Ethyl 3-ethoxypropionate 10.0
Ch
arge 5
t-Butyl perbenzoate- 20.0
Ethyl 3-ethoxypropionate 15.0
Charge 6
t-Butyl perbenzoate 20.0
Ethyl 3-ethoxypropionate 13.7
Charge 7
t-Butyl perbenzoate 20.0
Ethyl 3-ethoxypropionate 15.0
1 EKTAPRO~EEP solvent from Eastman Chemicals
2 t-amyl peracetate (60~) in odorless mineral spirits available from
Atochem
Charge 1 was heated in a suitable reactor to reflex. Charge 2
and Charge 3 were added simultaneously to the reaction vessel over a
period of about 4 hours then Charge 4 was added over a period of 30
minutes while maintaining the reaction at reflex. At the completion
of the additions, the reaction mixture was held at reflex for one
* Trade-mark
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24
hour, cooled to 130°C then Charge 5 was added over a period of 1
hour. The reaction was then held for 30 minutes at reflux. Charge 6
was added over a period of 1 hour and the reaction was held for
another 30 minutes at 130° C. Then Charge 7 was added over a period
$ of 1 hour and the reaction was held at 130°C for two hours. The
reaction mixture was then cooled to room temperature. The resultant
epoxy containing acrylic polymer had a total solids content of about
64.5 percent and a weight average molecular weight of about 2800.
The theoretical epoxy equivalent weight based on solids was 237.
BXAMPLB C
A polyacid curing agent was prepared from the following mixture
of ingredients:
1$ In-dredients W i~~ht in grams
Di-Trimethylolpropane 1584.8
Methylhexahydrophthalic anhydride 4120.7
Methyl isobutyl ketone 569.2
n-Propyl alcohol 2117.7
The di-trimethylolpropane and 559.2 grams of methyl isobutyl
ketone were charged to a reaction vessel and heated under a-nitrogen
atmosphere to 115°C. The methylhexahydrophthalic anhydride was added
over a period of about 2 hours at 115°C. The remainder of the methyl
2$ isobutyl ketone was added as a rinse. The reaction was held at 115°C
for 4 hours. The reaction mixture was then cooled to 100°C, and the
n-propyl alcohol was added. The reaction mixture was then heated to
105°C and held for 30 minutes and then cooled to room temperature.
The resultant product had a solids content of 72.3 percent and an
acid value of 163.
CA 02187371 1999-07-20
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EXAMPLE 1
A clear film-forming one package composition was prepared by
mixing together the following ingredients:
5 Ingredients Weight Resin
TINUVIN'328 3.0 3.0
TINUVIN 2922 0.4 0.4
Poly (Butyl acrylate)3 0.4 0.25
10 Epoxy containing acrylic 78.0 48.6
from EXAMPLE B
Polyacid curing agent 71.0 51.4
from EXAMPLE C
Ethyl 3-ethoxypropionate 40.0
1 Substituted benzotriazole UV light stabalizer available from Ciba
Geigy Co.
2 Sterically hindered tertiary amine light stabalizer available from
Ciba Geigy Co.
3 Available from E. I. duPont de Nemours and Company
In the following examples 2 to 5, the alkoxy silane polymer of
example A was formulated in the clear coating composition of example
1 above, at various levels (5, 10, 15, and 20 percent, respectively
based on resin solids). The coating compositions of Examples 1 to 5
were then evaluated for mar resistance over the pigmented basecoat
detailed in Example 6 which follows. The details of the evaluation
are presented below in Example 6 and the results are tabulated in
Table I.
sxAMpLE 2
A clear film forming one package composition was prepared by
mixing together the following ingredients:
Ingredients Weight Resin
in~c rams o~ ~ do
Clear film-forming composition 192.8 103.65
from EXAMPLE 1
Alkoxy silane solution polymer 7.3 5.0
from EXAMPLE A
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BXAMPLB 3
A clear film forming one package composition was prepared by
mixing together the following ingredients:
Ingredients Weight Resin
~ n drama O~ ~ d
Clear film-forming composition 192.8 103.65
1~ from EXAMPLE 1
Alkoxy silane solution polymer 14.6 10.0
from EXAMPLE A
EXAMPLB 4
A clear film forming one package composition was prepared by
mixing together the following ingredients:
Ingredients Weight Resin
n qrams So~~d
Clear film-forming composition 192.8 103.65
from EXAMPLE 1
Alkoxy silane solution polymer 21.9 15.0
from EXAMPLE A
2S EXAMPLg 5
A clear film forming one package composition was prepared by
mixing together the following ingredients:
Ingredients Weight Resin
. in aram So ~d
Clear film-forming composition 192.8 103.65
from EXAMPLE 1
Alkoxy silane solution polymer 29.15 20.0
from EXAMPLE A
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27
EXAMPLE 6
A black solventborne acrylic-melamine basecoat, commercially
available from PPG Industries, Inc. as NHU-9517, was spray applied to
$ steel test panels (B40, ED 5000 treatments on unpolished steel
available from ACT Corporation, Cleveland, Ohio). The basecoat was
given a 90 second flash at ambient conditions. Next, two coats of
the clear film forming compositions of Examples 1-5 were sprayed
applied over the basecoated test panels. The two coats of the
various clear film forming compositions were applied wet on wet to
the basecoated panels with a two minute flash under ambient
conditions between coats. After a final 5 minute flash at ambient
conditions the test panels were baked at 285°F (141°C) for 30
minutes. The total film thickness of the basecoat was about 0.8
mil., and the total film thickness of the various clearcoats was
between about 1.5 to 1.8 mil. The panels were then tested for mar
resistance using the following procedure.
1. Dry Bon-Ami"Cleanser (Feldspar/Calcite cleanser
manufactured by Faultless Starch/Bon Ami Company, Kansas
City, MO) was applied to one half of the test panel.
2. The excess cleanser was tapped off so that a thin film of
cleanser remained on the test panel.
3. The acrylic finger of an Atlas AATCC Crockmeter, model
CM-5 manufactured by Atlas Electric Devices Company,
Chicago, Illinois, was covered with a two inch by two
inch piece of felt cloth, obtainable from Atlas Electric
Devices.
4. The cleanser coated panel was rubbed with the felt cloth
ten times (ten double rubs) using the Crockmeter.
5. The test was repeated at least once changing the felt
cloth after each test.
6. After testing, the panel was washed with water to remove
the cleanser and then carefully dried.
* Trade-mark
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7. The 20° gloss was measured using a gloss meter
manufactured by Byk-Gardner Inc., Silver Spring MD, on
botH the unmarred part of the panel and the marred parts
of the panel. The difference in gloss was a measure of
S the mar resistance. The smaller the difference the
greater the mar resistance.
The test results are listed in the following table:
TABLE I
1~
20 Gloss
Basecoat Clearcoat UnmarredMarred
Example ThicknessThicknessDOIl Panel Panel Difference
in mils in mils Section Section
1 0.8 1.8 94 82 47 35
2 0.8 1.7 90 82 57 25
3 0.8 1.7 86 82 63 19
4 0.8 1.5 84 82 63 19
0.8 1.7 93 82 60 22
1 Determined by Dori-Gon Meter D47-6 manufactured by Hunter
Laboratories
Examples 3 and 4 exhibited the best improvement in mar
resistance in that they lost only 19 units of gloss when subjected to
the mar test described above. These results can be compared to
Example 1, which contains no alkoxy silane polymer additive, and a
difference of 35 units in gloss when subjected to the mar test.
The following examples D, E, F, G, H, and I show preparation of
a solution polymer, polyepoxide resin, polyacid curing agents, and
' fumed silica resin dispersion which are used in the preparation of a
two package film forming composition of Example 7.
CA 02187371 1999-07-20
WO 95!27760 PCT/US95/02721
29
EXAMPLE D
An alkoxy silane solution polymer was prepared from the
following mixture of ingredients:
Incrredi ents
W i,ght in grams
Chard
SOLVESSO-100 101.2
Charge 2
Di-tert-butylperoxide 40.6
1~ SOLVESSO-100 = 20.3
Charge 3
Gamma-Methacryloxypropyltrimethoxy si,lane 270.1
n-Butyl methacrylate 57.4
Styrene 3.4
Methyl methacrylate 3.4
2-Ethylhexyl acrylate 3.4
Char~4_
SOLVESSO-100 6.8
Charge 5
ZO SOLVESSO-100 6.8
Charge 1 was heated under nitrogen in a reaction vessel with
agitation to reflex temperature (155°C). At reflex the addition of
50.7 grams from Charge 2 was started to the reaction vessel over 3
hours. Five minutes after beginning the addition of Charge 2, the
2$ addition of Charge 3 was initiated and continued in a substantially
continuous manner over a period of 3 hours while maintaining the
reaction mixture at reflex temperature. At the completion of the
addition of Charge 3 the tank and lines were rinsed with Charge 4,
and the reaction mixture was held for 1 hour at reflex temperature.
30 The remaining 10.2 grams of Charge 2 was then added to the reactor
over a period of 30 minutes and then the tank and lines were rinsed
with Charge 5, and the reaction mixture was held for 2 hours at
reflex temperature to complete the polymerization. The reaction
mixture was cooled and filtered. The resultant polymer had a total
35 solids content of 69.6 percent determined at 110°C for one hour and
number average molecular weight of 1703 as determined by gel
permeation chromatography (GPC) using polystyrene standards.
CA 02187371 1999-07-20
WO 95/27760 PCT/US95/02721
EXAMPLE E
An epoxy containing acrylic resin was prepared from the
following mixture of ingredients:
5 Inctredients W ;ahr ;n drama
Charcxe 1
Xylene 3196.0
1 ~ ~g~
Glycidyl methacrylate - 2160.0
Methyl methacrylate 1782.0
n-Butyl Acrylate 1350.0
Styrene 108.0
15 Xylene 30.0
Cha~g~
VAZO~-671 162. 0
t-Butyl perbenzoate 108.0
2~ Xylene 330.0
Charge 4
t-Butyl perbenzoate 27.0
Xylene 130.0
25 Charae 5
t-Butyl perbenzoate 27.0
Xylene 130.0
3~ 1 2, 2' azobis(2-methylbutane) nitrile available from E. I. duPont de
Nemours and Company
Charge 1 was placed into a suitable reactor and heated under a
nitrogen atmosphere to reflex. Charge 2 and charge 3 were added
simultaneously to the reaction vessel over a period of 3 hours and
then the reaction was held at reflex for 30 minutes. Charge 4 was
then added over 30 minutes and the reaction mixture was held at
reflex for 30 minutes. Finally charge 5 was added over 30 minutes
and the reaction mixture was then held at reflex for 2 hours. The
reaction mixture was then cooled to room temperature. The reaction
mixture had a total solids content of about 59.5 and a weight average
molecular weight of about 5831.
* Trade-mark
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PCT/LIS95102721
31
EXAMPLE F
A polyacid resin was prepared from the following mixture of
ingredients:
Tnc~red~ ents W , ght~n ram..
harg~
Trimethylolpropane 134.1
Hexahydrophthalic anhydride 151.1
Methyl isobutyl ketone 244.0
Charg~2
Methylhexahydrophthalic anhydride 352.5
Methyl isobutyl ketone 20.0
Ethyl alcohol 9.3
1$
Charge 1 was placed into a suitable reactor and heated under a
nitrogen atmosphere to 115°C. Charge 2 was added over 1 to 2 hours,
the reaction mixture was held at 115°C for 4 hours, and then cooled
to 100°C followed by the addition of Charge 3. The reaction mixture
was then heated to 105°C, held for 30 minutes, and then cooled to
room temperature. The reaction mixture had a solids content of 69.5
percent and an acid value of 189.5.
WO 95/27760 ~ 18 7 ~ 7 ~ p~~S95102721
-..
32
EXAMPLE G
A polyacid resin was prepared from the following mixture of
ingredients:
Inaredients Weight in grams
Charge 1
Ester Diol 2041 2856.0
Hexahydrophthalic anhydride 1336.7
Methyl isobutyl ketone 1725.1
Charge 2
1$ Methylhexahydrophthalic anhydride 3155.2
Methyl isobutyl ketone 20.0
Charge 3
ethyl alcohol gl.g
1 1-(3-hydroxy-2,2-dimethylpropyl)-3-hydroxy-2,2-dimethylpropionate
available from Shell
Charge 1 was placed in a suitable reactor and heated under a
nitrogen atmosphere to 115°C. Charge 2 was added over 1 to 2 hours
and then the reaction mixture was held at 115°C for 4 hours, and then
cooled to 100°C followed by the addition of Charge 3. The reaction
mixture was then heated to 105°C, held for 30 minutes, and then
cooled to room temperature. The reaction mixture had a solids
content of 79.5 percent and an acid value of 167.6.
EXAMPLE H
An anhydride copolymer was prepared from the following mixture
of ingredients:
2ggredients
Weight in grams
1-Octene 1246.0
LUPERSOL 555-M60 363.4
Butyl acetate 18.5
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33
Malefic anhydride 545.1
Butyl acetate 1308.3
S Butyl acetate 18.5
Charge 1 was placed in a suitable reactor and heated under a
nitrogen atmosphere to reflux. Charge 2 and charge 3 were added
simultaneously over a period of 2 hours and the reaction mixture was
then held at reflux for 1 hour, and then heated to 130°C and held for
1 hour. The reaction mixture was then cooled to room temperature.
The reaction mixture had a total solids content of 73.3 percent.
EXAMPLB I
A fumed silica grind was prepared by mixing the following
ingredients, grind loading the mixture into a mill and grinding to a
number 7 Hegman.
Ia~d; ents w ; ght i ,.n a",~
RESIMENE' HM-75541 360.1
n-amyl alcohol 395.7
AEROSILr R812Z 65.7
1 Aminoplast resin available from Monsanto
2 Hydrophobic silicon dioxide available from Degussa
_ EXAMPLE 7
A clear film-forming two package composition was prepared by
mixing together the following ingredients:
Ingredients weight Resin
;n cram o~;d~
Pack - A
DOWANOLi DPM1 5.0
TINWIN 328 2.65 2.65
TINWIN 292 0.35 0.35
Poly(Butyl acrylate) 0.42 0.25
MULTIFLOW2~ 0.50 0
25
ERL-42213 19.0 .
19
0
RESIMENE 7174 13.3 .
10.6
* Trade-mark
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WO 95/27760 PCT/CTS95/02721
34
Acrylic resin 32.4 29.0
from EXAMPLE E
Fumed silica grind 8.1 2.9
from EXAMPLE I
$
Pack - B
Polyacid polymer 34.3 24.0
from EXAMPLE F
Polyacid polymer 15.1 11.0
from EXAMPLE H
Polyacid polymer 11.9
9.5
from EXAMPLE G
Isostearic acid 4.0 4
0
1$ DM-12D5 4 .
0
. 4.0
.
Methyl isobut~l ketone 8.0
Hexyl acetate g,0
1 Dipropylene glycol monomethyl ether from Dow Chemical
available
2 5og solution of ethyl acrylate/2-ethylacrylate copolymer
hexyl
available from Monsanto
3 Dicycloaliphatic epoxide available Carbide
from Union
4 Aminoplast resin available from Monsanto
5 N,N-Dimethyl-1-Aminododecane avilablezo Chemical
from Ak
2$ 6 EXXATE' 600 available from Exxon Company
* Trade-mark
WO 95/27760 PCT/US95/02721
2187 ~7 ~
In the following examples a and 9, the alkoxy silane polymer of
example A was formulated in the clear film forming composition of
example 7 above, at various levels (5 and 10 percent, respectively
based on resin solids). These coating compositions were then
5 evaluated for mar resistance over the pigmented basecoat detailed in
Example 10 which follows. The details of the evaluation are
presented below in Example l0 and the results tabulated in Table II.
LXAMPLB 8
10 A clear film forming two package composition was prepared by
mixing together the following ingredients:
Ingredients Weight Resin
in crrams Sol~ ds
15 Clear film forming composition 167.0 104.0
from EXAMPLE 7
Alkoxy silane solution polymer 7.1 5.0
from EXAMPLE D
20 ~xA~PL$ s
A clear film forming two package composition was prepared by
mixing together the following ingredients:
25 Ingredients Weight Resin
in grams Solids
Clear film forming composition 167.0 104.0
from EXAMPLE 7
Alkoxy silane solution polymer 14.2 10.0
30 from EXAMPLE D
WO 95/27760 ~ ~ 7 ~ PCT/US95102721
36
EXAMPLE 10
A black solventborne acrylic-melamine basecoat, commercially
available from PPG Industries, Inc. as NHU-9517, was spray applied to
$ steel test panels (B40, ED 5000 treatments on unpolished steel
available from ACT Corporation, Cleveland, Ohio). The basecoat was
given a 90 second flash at ambient conditions. Next two coats of the
clear film forming compositions of Examples 7-9 were sprayed applied
over the basecoated test panels. The two coats of the various clear
film forming compositions were applied wet on wet to the basecoated
panels with a two minute flash under ambient conditions between
coats. After a final 5 minute flash at ambient conditions the test
panels were baked at 250°F (121°C) for 30 minutes. The total
film
thickness of the basecoat was about 0.8 mil., and the total film
1S thickness of the various clearcoats was between about 1.5 to 1.8 mil.
The panels were then tested for mar resistance using the procedure
described in Example 6 above.
The test results are listed in the following table.
20 Gloss
Basecoat Clearcoat UnmarredMarred
Example ThicknessThickness DOI1 Panel Panel Difference
in mils in mils Section Section
7 0.8 1.8 97.8 84 59 25
8 0.8 1.7 97.3 84 68 16
9 0.8 1.7 94.1 84 69 15
1 Determined by Dori-Gon Meter D47-6 manufactured by Hunter
Laboratories
Examples 8 and 9 exhibited improved mar resistance in that they
lost only 16 and 15 units of gloss, respectively when subjected to
the mar test described above. These results can be compared to
Example 7, which contains no alkoxy silane polymer additive, and a
difference of 25 units in gloss when subjected to the mar test.
