Hydroxyl-contg. copolymer coating resin binders - obtd. from styrene, methyl methacrylate, hydroxyethyl methacrylate, acrylic acid and glycidyl esters

摘要

Hydroxy gp. contg. copolymers which can be cured with polyisocyanates are made by polymerising a mixt. of (a) 20-25.9 wt.% styrene; (b) 20-24 wt.% methyl methacrylate, (I); (c) 18-24 wt.% hydroxyethyl methacrylate (II); (d) 8.5-11 wt.% acrylic acid (III) and (e) 29.0-35 wt.% glycidyl esters of alpha-alkylalkane monocarboxylic acid and/or alpha, alpha'-dialkylalkane monocarboxylic acids of formula C13H24O3. Polymerisation is carried out under simultaneous esterification and polymerisation conditions in an inert organic solvent, in the presence of polymerisation initiators and opt. chain transfer agents. Ratio of components used is such that the prod. contains 4.0-5.5%, esp. 4.1-4.8 wt.% OH gps. (on monomers). The molar ratio (d): (e) = 1.01-1.1:1.0, and the reaction is continued until the acid value of the prod. is 6-12. Copolymers have good solubility characteristics and are esp. useful as binders in coating resin formulations which cure with organic polyisocyanates to give hard durable films with excellent mechanical properties and resistance to water. They have good pigment compatibility and are esp. useful as finished for wood, metals, textiles and paper, particularly as enamels for (re)finishing of motor vehicles.