Coating Composition and Cured Film Formed Therefrom

Abstract

A coating composition comprises a first copolymer and a second copolymer. The first copolymer has at least one linear polymer strand having a weight average molecular weight of at least 1,500 Daltons and functionality X with an equivalent weight of no more than 500. The second copolymer has at least one linear polymer strand having a weight average molecular weight of at least 1,500 Daltons and functionality X′ with an equivalent weight of no more than 1,500. The coating composition is free of gloss flattening agents, yet still produces a cured film having a low gloss of less than 70 gloss units at an angle of incidence of 60°, as measured according to ASTM D 2457.

Description

FIELD OF THE INVENTION[0001]The present invention generally relates to a coating composition. More specifically, the present invention relates to a coating composition which is free of gloss flattening agents yet still produces a cured film having low gloss.DESCRIPTION OF THE RELATED ART[0002]Coating compositions are known in the art and are applied to a substrate to form a cured film prior to an end use of the substrate. Typical end uses of the substrate include appliances, automotive parts, building and construction, and tractor-trailer equipment applications. The cured film is employed to provide aesthetic qualities and to increase durability and longevity of the substrate, such as by passivating the substrate, i.e., maximizing resistance to corrosion of the substrate. For example, it is advantageous to form the cured film on automotive parts because the cured film increases the durability and resistance to corrosion of the automotive parts, thereby increasing longevity of the au...

AI Technical Summary

Benefits of technology

[0009]The coating composition of the present invention forms a cured film having excellent low gloss properties. The excellent low gloss properties are attributable to the first copolymer and the second copolymer, as opposed to flattening agents, and, as such, the low gloss properties of the cured film cannot be lessened and / or eliminated by polishing or otherwise smoothing a surface of the cured film. Therefore, the cured film also has excellent durability in comparison with other low gloss cured films that include gloss flattening agents because the gloss flattening agents degrade over time.

Problems solved by technology

The excess amount of the flattening agent in the coating compositions coagulates, thereby resulting in an undesirable “seedy” surface appearance of the resulting low gloss cured films.

The surface of the low gloss cured film having the seedy appearance does not allow for reflection of light because the light is scattered at random angles by the surface, thereby imparting the low gloss cured film with the lower gloss.

However, the surface of the low gloss cured film having the seedy appearance also has adverse effects on durability of the low gloss cured film because the flattening agent is eroded over time, which in turn erodes the low gloss cured film.

In addition, the excessive amount of the flattening agents in the coating compositions typically makes the low gloss cured films more brittle than conventional cured films.

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