Primer compositions based on modified chlorinated polypropylenes

摘要

The present invention provides a primer composition for polyolefins, which comprises: acid anhydride-modified polypropylene chloride (A), which includes polypropylene chloride moiety (a1) and acid anhydride moiety (a2) bonded thereto, and has a chlorine content of 19.5 to 20.5 wt %, an acid anhydride moiety content of 0.8 to 1.2 wt %, and a weight-average molecular weight of 30,000 to 36,000; and acryl-modified polypropylene chloride (B), which includes polypropylene chloride moiety (b1) and acrylic polymer chain moiety (b2) as grafted thereon, and has a weight-average molecular weight of 30,000 to 200,000, wherein: polypropylene chloride moiety (b1) has a chlorine content of 20 to 30 wt %; acrylic polymer chain moiety (b2) has a glass transition temperature of 60 {C or higher; and the ratio by weight between moieties (b1) and (b2) is b1/b2 = 5/95 to 50/50; wherein the ratio by weight between acid anhydride-modified polypropylene chloride (A) and acryl-modified polypropylene chloride (B) is A/B = 90/10 to 20/80. The anhydride is preferably maleic anhydride grafted onto the PP. The chloride moreties may be introduced by chlorination of polypropylene. The composition has good adhesion to polyolefin base materials and resistance to e.g. high pressure washing.