Copolymers containing amino groups, process for their preparation and their use in coating agents

Claim 1

A copolymer (B), containing amino groups, obtained by reacting a first copolymer (A) with polyamines, wherein copolymer (A) contains alkyl ester groups, and is synthesized from a1) 5 to 25% by wight of one or more vinyl esters of monocarboxylic acids, a2) 10 to 50% by weight of one or more vinylaromatic hydrocarbons, a3) 10 to 40% by weight of one or more alkyl esters of aliphatic, olefinically unsaturated carboxylic acids having 1 to 6 C atoms, in the alkyl radical and a4) 0 to 40% by wight of other ethylenically unsaturated copolymerizable monomers, the sum of components (a1) to (a4) in each case being 100% by weight, and wherein the copolymer (A) is prepared by the process of free radical solution polymerization at temperatures of 130° to 200° C., wherein the free radical polymerization process includes the steps of i) initially introducing at least between 60% by weight, of the total amount of components a1, ii) metering in components a2 to a4 and any remainder of component a1 within a monomer addition period which is of equal length for all the components such that 1) the amount of component a1 added per unit time remains constant or decreases within the monomer addition period, 2) the amount of components a3 and a4 added power unit time remains constant within the monomer addition period and 3) the amount of component a2 added within the first third of the monomer addition period is 15 to 30% by weight, and within the second third is 25 to 40% by weight, and within the last third is 35 to 60% by weight of ht total amount of component a2, and wherein the resultant copolymer (B) containing amino groups has an amine number of 30 to 150 mg of KOH/g and an average molecular weight of 1,500 to 8,000.