Copolymers with OH functions, with low molecular weight and high chain branching, process for their preparation, and their use

摘要

Low-mol. wt. copolymers (I) with a wt.-average mol. wt. (Mw) of less than 3500 contain at least 20 wt.% of components with branched side chains, obtd. by the reaction of (aa) glycidyl ester(s) of satd. aliphatic monocarboxylic acids with a tert. or quat. alpha -C atom; and (ab) at least two unsatd. comonomers, at least one of which contains at least one COOH gp., under radical copolymerisation conditions. Also claimed are (i) prepn. of (I) by heating component (aa) to 210-260 degrees C and reacting with component (ab) (which contains at least 2.0 wt.% of a COOH gp.-contg. monomer) in the presence of radical initiator(s), to a degree of conversion of at least 95 (pref. at least 97.5) %; (ii) polymer mixts. contg. (I), obtd. by reaction of (aa) and (ab) as above in at least two time intervals with a constant temp. in each interval, using at least two different reaction temps., at least one of which is in the range 210-260 degrees C; (iii) polymer mixts. contg. (I) and other polymers etc.; (iv) binders for coating materials contg. (I) or the above polymer mixts.; (v) coating materials contg. binders as above and hardeners such as amino resins, capped or uncapped polyisocyanates or organic cpds. with acid and/or anhydride gps.