Process for producing powdered copolymers of ethylenically unsaturated compound and maleic anhydride or an ester thereof

Claim 1

A process for producing a powdered copolymer of an ethylenically unsaturated compound having a terminal double bond and maleic anhydride or an ester derivative thereof, which comprises polymerizing a polymerizable reactant mixture comprising an ethylenically unsaturated compound having a terminal double bond and being represented by the general formula: ##STR3## wherein R 1 is hydrogen, an alkyl group having 1 to 15 carbon atoms, an aryl group, --OR 3 , ##STR4## and R 2 and R 3 are independently hydrogen or an alkyl group having 1 to 10 carbon atoms, and maleic anhydride or an ester derivative thereof in a kneading machine with continuous kneading of the reactant mixture in the presence or absence of a poor solvent for the copolymer to form a highly viscous resin phase containing the copolymer produced and remaining polymerizable reactant mixture at least one reactant of which is capable of dissolving the copolymer, further kneading the highly viscous resin phase, effecting further polymerization of the resin phase while kneading is continued with tearing of the resin phase to produce solid resin aggregates containing said copolymer, and continuing the kneading to effect powdering of the solid resin aggregates to produce a powdered copolymer; the internal free volume of the kneading machine being about twice or more of the volume of the reactant mixture or the total volume of the reactant mixture and the poor solvent for the copolymer.