Coating material for painting cars

摘要

A coating cpd. for cars consists of (A) an acrylic resin and (B) a blocked isocyanate hardener in an amt. of 0.9-1.5 equivs. w.r.t. equiv. units of (A). Pref. (A) has an acid no. of 5-30, an OH no. of 50-200, a mean mol.wt. of 500-10,000, a Tg of -10 to -70 deg. C and a branched- chain or graft copolymer structure. (A) is prepd. by the soln. polymerisation of typical acrylic monomers and acrylic monomers with COOH, OH and/or silane gps., pref. from a mixt. of an alkyl acrylate of formula CH2=CR1-COOR2 (with R1 = H or Me; R2 = 1-14C alkyl) (I), a vinylaromatic cpd. of formula R-CH=CH2 (with R = aryl) (II) a reactive monomer (III). Pref. (I) is methyl, ethyl, propyl, butyl, 2-ethylhexyl, lauryl or cyclohexyl (meth)acrylate etc. (19 cpds. listed). Pref. (II) is styrene, alpha-methylstyrene, benzyl (meth)acrylate, phenyl (meth)acrylate and/or vinyltoluene. Pref. (III) is e.g. hydroxyethyl or hydroxypropyl (meth)acrylate, (meth)acrylic, crotonic, itaconic, fumaric or maleic acid, vinyltrichlorosilane, dimethylaminoethyl methacrylate, butoxymethyl-acrylamide, acrylamide etc. (22 cpds. listed). (A) is a copolymer of 20-70 wt.% (I), 10-40 wt.% (II) and 5-40 wt.% (III). (B) is obtd. by masking an aliphatic isocyanate (IV) with a blocking agent (V), modifying with alcohol and subjecting the modified isocyanate to soln. polymerisation. Pref. (IV) is HDI monomer, HDI trimer (chain or ring type), IPDI monomer or IPDI trimer; this is masked with 50-90 wt.% non-yellowing blocking agent (V), pref. a malonate, and then modified with 10-40% polyglycol.