Polyester based coating composition for anti-stain PCM outside panel

#1. Field of the Invention

#This invention relates to a polyester based coating composition for anti-stain PCM outside panel and more particularly, to the polyester based coating composition for anti-stain PCM outside panel having an excellent combination of physical properties such as surface compactness, anti-contamination effect, acid resistance and self-cleaning effect, wherein the polyester based coating composition comprises:

#a) hydroxyl unsaturated polyester resin and a melamine curing agent as main ingredients, b) sulfonic acid blocked with a secondary amine or epoxy resin, c) sulfonic acid blocked with a tertiary amine, d) an isocyanate compound blocked with malonate, e) a tin based curing catalyst, f) polyalkyl silicate, and g) an alkoxy compound; further, the polyester based coating composition for anti-stain PCM outside panel can demonstrate other excellent properties such as appearance and workability even without addition of any defoaming agent and leveling agent by adjusting the compatibility of both hydroxy unsaturated polyester resin and polyalkyl silicate.

#This invention herein is explained in more detail based on the following examples without limitations thereby.

#The polyester based coating composition was formulated based upon the chemical contents represented by the following table 1a and 1b. The coating process was performed in the following conditions: a) primer coating process with a thickness of 5 to 7 μm using EJ2751-Y005 (Korea Chemicals), an epoxy-modified polyester primer, and b) baking at 280 for 22 seconds with wind velocity 2 m by controlling the highest temperature of material during the baking process to be 210 to 216. Hence, a #14 bar coating was employed. For the baking, an automatic discharge oven (Korea Taesung Engineering) was employed. A coating substrate was a galvanize iron plate of 0.45 mm, prepared by Korea Posco at Kwangyang Bay. The content of zinc on this plate was 87 mg/m2. The pretreatment of galvanize iron was made by non rinse chromate (NRC; Korea Parkerizing Co.) with a coating amount of 20 to 40 mg/m2.

#Further, the chemical composition of the following table 1a and 1b was based upon the solid contents, except for the coating solvents. The coating solvents were used to adjust the flowing property and viscosity of the paint during production.