Aqueous thermoplastic coating composition for plastics materials and coating method using same

Abstract

Disclosed are (1) an aqueous thermoplastic coating composition for coating plastics substrates, the composition consisting essentially of: (A) an aqueous acrylic resin and (B) a urethane resin emulsion, the component (B) being a self-emulsifiable urethane emulsion prepared by subjecting a urethane prepolymer to reaction for chain extension by water and emulsification after or during neutralization of the urethane prepolymer with a tertiary amine, the urethane prepolymer consisting essentially of (i) an aliphatic and/or an alicyclic diisocyanate, (ii) a polyether diol and/or polyester diol both having a number-average molecular weight of about 500 to about 5000, (iii) a low-molecular weight polyhydroxyl compound and (iv) a dimethylolalkanoic acid in NCO/OH equivalent ratio of 1.1-1.9 : 1, the amount of the component (A) being about 1 to about 12% by weight and the amount of the component (B) being about 99 to about 88% by weight, based on the combined weight (calculated as solids) of the two components; and (2) a two-coat coating method for coating a plastics substrate, the method comprising the steps of coating a plastics substrate with a base-coat composition containing a coloring pigment and/or metallic pigment, applying a clear coat composition to the cured or uncured coating for forming a transparent coating and curing the clear coating or the two coatings at the same time at a temperature lower than about 120.degree. C., the method being characterized by the use of the aqueous thermoplastic coating composition as defined above in (1) as the base-coat composition.

Dependencies are inferred from the claim text.