Basf Coatings Ag

Basf Lacke+farben Ag

Yoshiaki Kawamura

Yoshiaki Matsukura

Hitoshi Taniguchi

Atsuhiro Sakai

Provided are paint films with outstanding paint film performance traits such as water resistance and chemical resistance, etc., and outstanding finished appearance. The water-based paints are easy to apply and have outstanding storage stability. The invention further provides an acrylic graft copolymer obtained by reacting a acrylic copolymer (a) of acid number 35 to 120 mg KOH/g, hydroxyl group number 50 to 150 mg KOH/g, glass transition temperature -20 to +50.degree. C. and number average molecular weight 4500 to 9000, and a monomer combination (b) comprising an unsaturated monomer (b1) containing a glycidyl group and an unsaturated monomer (b2) containing a hydroxyl group to give an acid number of .ltoreq.15 mg KOH/g and a hydroxyl group number of 50 to 150 mg KOH/g. Copolymer (a) and monomers (b) are reacted in specified proportions in a single stage to make the claimed water-dispersible acrylic graft copolymer which has an acid number of 10 to 30 mg KOH/g, a hydroxyl group number of 50 to 150 mg KOH/g, a glass transition temperature of -20 to +50.degree. C. and a number-average molecular weight of 10,000-100,000 by grafting side chains formed from the aforementioned (b) to a main chain from the aforementioned (a), and this graft copolymer is dispersed in an aqueous medium to obtain the claimed water-based paint.

Water-dispersible acrylic based graft copolymers, a method for making

Water-based paint composition

Provided are aqueous paints with which paint films which have excellent paint film properties such as water resistance and resistance to chemical attack, and excellent finished appearance are obtained, and which have excellent painting operability and storage stability. The invention further provides water dispersible acrylic based graft copolymers, aqueous paints incorporating same and a method to make such paints, wherein an unsaturated bond-containing acrylic based copolymer (a) obtained by reacting an acrylic based copolymer (a1) of acid value 35-120 mg.KOH/gram, hydroxy group value 50-150 mg.KOH/gram, glass transition temperature -20.degree.-+50.degree. C. and number average molecular weight 4500-9000 and an unsaturated monomer mixture (a2), which has functional groups which can react with hydroxy groups, in a mol ratio of a2/a1=0.4-1.5, and a monomer composition (b) compounded in such a way that the acid value is not more than 15 and the hydroxy group value is 50-150 are reacted in the proportions by weight of a/b=10/90-60/40 to produce the claimed water dispersible acrylic based graft copolymer.

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Kamakura, Japan

Yoshiaki Kawamura