Process of producing block copolymers of n-vinyl pyrrolidone

Claim 1

A PROCESS FOR PRODUCING A COPOLYMER OF N-VINYL PRYRROLIDONE AND VINYL CHLORIDE COMPRISING A MIXING N-VINYL PYRROLIDONE AND VINYL CHLORIDE IN A MOL RATIO VARYING FROM 1.9 TO ABOUT 8.4 MOLS OF N-VINYL PYRROLIDONE PER MOL OF VINYL CHLORIDE AND MIXING AN AMOUNT OF WATER TO PROVIDE A MOLE RATIO OF N-VINYL PYRROLIDONE TO WATER VARYING FROM ABOUT 0.5 TO 1.0 TO ABOUT 1.0 TO 2.0, AND FROM A HOMOGENEOUS MIXTURE OF N-VINYL PYRROLIDONE, VINYL CHLORIDE AND WATER, POLYMERIZING SAID HOMOGENOUS MIXTURE BY ADDING AZOBUTYRIC ACID NITRILE AS POLYMERIZATION CATALYST IN A CONCENTRATION OF FROM ABOUT 0.2% TO ABOUT 0.5%, SAID POLYMERIZATION BEING CARRIED OUT IN THE ABSENCE OF ATMOSPHERIC OXYGEN WHEREBY THERE IS OBTAINED A COPOLYMER OF N-VINYL PYRROLIDONE AND VINYL CHLORIDE HAVING A LOWER SOLUBILITY IN WATER THAN THE PRODUCT OBTAINED BY USING THE SAME MONOMERS WHICH ARE POLYMERIZED IN THE ABSENCE OF WATER AND HAVING A LOWER INTERFACIAL TENSION BETWEEN BENZENE AND WATER AND THE PRODUCT POLYMERIZED IN THE ABSENCE OF WATER.