Preparation of finely divided pulverulent crosslinked copolymers

A process for the preparation of a pulverulent crosslinked copolymer, comprising polymerizing a monomer mixture consisting of

• (a) from 70 to 99.999% by weight of monoethylenically unsaturated carboxylic acids, amides of such carboxylic acids and/or esters of such carboxylic acids and amino alcohols of the formula ##STR3## where R is C.sub.2 -C.sub.6 -alkylene and R.sup.1 and R.sup.2 are each H, CH.sub.3, C.sub.2 H.sub.5 or C.sub.3 H.sub.7,
• (b) from 0.001 to 10% by weight of a diethylenically or polyethylenically unsaturated monomer and
• (c) from 0 to 20% by weight of other monoethylenically unsaturated monomers
• in supercritical carbon dioxide at up to 150.degree. C. and under pressures above 73 bar in the presence of a free radical initiator, from 100 to 1,500 parts by weight of carbon dioxide being used per 100 parts by weight of the monomers employed in the polymerization, and removing the carbon dioxide after the polymerization resulting in a fine polymer powder consisting of primary particles of 0.5 .mu.m to 3 .mu.m in diameter.