Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1996-06-26
1998-10-27
Gulakowski, Randy
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
525438, 525530, 525533, 428413, C08L 6300, C08F 2000
Patent
active
058279105
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a curable coating composition particularly useful as a top coat in multi-layered coating systems.
Base coat-clear coat systems have found wide acceptance in the past decade as automotive finishes. Continuing effort has been directed to such coating systems to improve the overall appearance, the clarity of the top coat, and the resistance to deterioration. Further effort has been directed to the development of coating compositions having low volatile organic content (VOC).
Previous efforts at improving the etch resistance and durability of coating had suggested the use of anhydride resins having pendant non-cyclic anhydride moieties in combination with resins that react with the polyanhydride resins to cure under curing conditions. See U.S. Pat. No. 5,428,082. However, a continuing need exists for coating formulations which provides outstanding performance characteristics after application, and particularly resistance to environmental etching.
Moreover, effort has previously been directly toward the development of mar-resistant clear coatings. While such coatings have previously been prepared, the mar-resistance was attained by softening the coating, which depreciates other performance characteristics.
SUMMARY OF THE INVENTION
The present invention provides a sprayable coating composition which, through the selection of the chemical makeup and molecular weight of the components, provides a fully formulated coating composition which, at a low VOC, can be easily applied, and exhibits outstanding appearance and durability after application and ease of maintenance. In addition, the present coating, when applied to a substrate, exhibits excellent mar-resistance at high hardness, as well as the ability to "heal" mars by heat and solvent treatment.
Specifically, the instant invention provides a curable coating composition comprising organic solvent and binder comprising
(a) at least about 10%, on the basis of components (a) and (b), of an anhydride resin having a molecular weight of less than about 2000 that contains (1) a central moiety, and (2) on average, at least three pendant, non-cyclic anhydride moieties bonded to each central moiety;
(b) at least about 10%, on the basis of components (a) and (b), of a compound having at least two noncyclic acid anhydride groups and represented by the following formula ##STR2## wherein R is a monovalent hydrocarbon group having 1 to 50 carbon atoms, R' is independently selected from a bivalent hydrocarbon groups having 2 to 50 carbon atoms, the hydrocarbon groups R and R' containing or not containing an ether linkage, urethane linkage or ester linkage, and n is an integer of 1 to 500.
(c) at least one organic component having at least 2 epoxy groups and;
(d) a functional amount of at least one catalyst, wherein the ratio of equivalents of epoxy to anhydride is about from 0.7 to 1.4.
This invention also concerns a composition as described above wherein the epoxy component is the diglycidyl ester of 1,2-cyclohexane dicarboxylic acid; and wherein R and R' in the linear anhydride (b) are both aliphatic moieties having up to 12 carbon atoms and n is an integer of 1-20; and wherein R in the linear anhydride has 8 carbon atoms and R' is a 50% molar blend of aliphatic hydrocarbon groups having four and seven carbon atoms, respectively, and n is 10; and a composition as above further comprising from 1 to 200 parts by weight, per 100 parts of components (a) and (b), of pigment; and such composition applied to a substrate.
DETAILED DESCRIPTION OF THE INVENTION
A first class of anhydride resin which can be used in the present invention includes those having a molecular weight of less than about 2000 having a central moieties and more than one pendant, non-cyclic anhydride moiety bonded to each central moiety. This anhydride resin, having pendant, non-cyclic anhydride moiety should comprise at least about 10% of the mixture of this anhydride and the liner anhydride. This first anhydride is asymmetrical, and preferably c
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patent: 5017435 (1991-05-01), Barsotti et al.
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patent: 5466752 (1995-11-01), Barsotti et al.
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Barsotti Robert J.
Nordstrom J. David
E. I. Du Pont de Nemours and Company
Gulakowski Randy
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