Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1987-08-21
1989-05-09
Short, Patricia
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
528302, 528307, C08L 6702
Patent
active
048291323
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to resinous composition for coating use and more specifically a coating composition which is useful as a top coat for automobile bodies and the like and is excellent in weather resistance, mechanical properties of the film, interlaminar adhesion and particularly in the curability thereof.
BACKGROUND OF THE INVENTION
Recently, as a top coat for automobile bodies and the like, has been welcomed a coating composition which is excellent in weather resistance, mechanical properties of the film, and interlaminar adhesion and oil-free polyester/amino aldehyde reinous system is now receiving increased attention. However, this type of coating composition is apt to result, in considerable cising and hence is difficult to make produce a uniform coating, since a coating having an inferior glossy surface is formed which shows poor compatibility with the amino resin, and for these reasons, it is difficult to apply such coatings to automobile bodies and the like. Under the circumstances, as an attempt of overcoming the defect possessed by heretofore known oil-free polyester/amino resins coating compositions, as mentioned above, while maintaining the advantages thereof, a proposal has been made to use a larger quantity of a saturated alicyclic polycarboxylic acid or a combination of an aromatic polycarboxylic acid and a saturated alicyclic polycarboxylic acid as an acid component of a oil free polyester resin (Japanese Patent Application Kokai No. 20068/81). The use of such saturated alicyclic acid modified polyester resin (hereinafter merely called a modified polyester resin), however, serves only to some extent to improve the occurence of cissing, dim gloss and poor compatibility with said amino resin, and therefore, it is difficult to overcome the aforementioned shortcomings. Moreover, a new problem of insufficient curing occurs due to the modification with said saturated alicyclic acid, making it very difficult to put the resin in practical use. Therefore, an object of the present invention is to provide a coating composition which retains the excellent qualities of a known oil-free polyester/amino resin system, but which is free from the defects of insufficient curing inevitably produced by the use of such modified polyester resin, but which still exhibits excellent gloss and weather resistance properties. According to the studies of the present inventors, it has been found that the employment of saturated alicyclic polycarboxylic acid as a part of said acid component of polyester resin is indeed very effective for improving the weather resistance of the coating, but when the resin is mixed with a melamine resin and a cured film formed, it will cause the problem of reduced initial gloss and inferior curing and the inclusion of an aromatic polycarboxylic acid component is indeed of advantage in obtaining a film with improved gloss and curing properties, however, barely results in a film having advanced weather resistance. The inventors also have found that even if both a saturated alicyclic polycarboxyl acid and an aromatic polycarboxylic acid are used together for the purpose of obtaining a resinous film with excellent weather resistance, gloss and curing properties, this cannot always be achieved. This is because the reactivity of the saturated alicylic acid is rather poor, the aromatic polycarboxylic acid is more quickly incorporated into the polyester chain and the carboxyl groups contribute to the development of resinous acid values which may be occupied, in substance, by the alicyclic carboxylic acid with low dissociation in a non-aqueous medium, thereby resulting in resinous product with weak acidity. Thus, the present objectives of producing a resin with improved curing properties and yet possessing the capablity of producing a film with excellent weather resistance cannot be attained. In order to attain the objective of the present invention, it is essential that in addition to modifying the polyester with a saturated alicyclic acid (for improving the w
REFERENCES:
patent: 3691258 (1972-09-01), Riemhofer
patent: 4204014 (1980-05-01), Dorffel
Nakano Shinji
Tanabe Hisaki
Umemoto Hirotoshi
Nippon Paint Co. Ltd.
Short Patricia
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