Process for preparation of quaternized cationic vinyllactam-acrylamide copolymers

The process which comprises the steps sequentially in combination:

• A. copolymerizing between about 30 and 95 percent by weight of a N-vinyllactam having the formula:
• ##STR6## wherein R is hydrogen, methyl or ethyl and n is an integer of 1 to 3, with between about 5 and about 70 percent by weight of acrylamide or methacrylamide in a nonacidic aqueous solution in the presence of a free radical catalyst at a temperature of between about 25.degree. and about 150.degree. C.;
• B. reacting the resulting copolymer with formaldehyde and a secondary amine having the formula:
• ##STR7## wherein R.sub.2 and R.sub.3 are independently selected from the group consisting of alkyl having from 1 to 4 carbon atoms, hydroxyalkyl having from 1 to 4 carbon atoms and together may represent morpholine, to produce the corresponding cationic vinyllactam-acrylamide copolymer;
• and
• C. quaternizing the cationic polymer by reacting with a compound selected from the group consisting of a benzyl halide, an alkyl halide having from 1 to 6 carbon atoms, an alkyl sulfate having from 1 to 6 carbon atoms, an alkyl ester of sulfonic acid having from 1 to 6 carbon atoms and mixtures thereof to produce a quaternized copolymer having a K value less than 200 consisting essentially of the following recurring units in primarily random distribution:
• ##STR8## wherein R, R.sub.2, R.sub.3 and n are as defined above;
• R.sub.1 is selected from the group consisting of hydrogen and methyl;
• R.sub.4 is selected from the group consisting of alkyl having 1 to 6 carbon atoms and benzyl radicals in an amount of 10 to 100% by weight and hydrogen in an amount of 0 to 90% by weight;
• X represents an anion;
• Z is selected from the group consisting of hydrogen and ##STR9## wherein R.sub.2, R.sub.3, and R.sub.4 are as defined above;
• a represents from 30 to 95 percent by weight of the lactam moiety in the copolymeric product;
• b represents from 5 to 70 percent by weight of the acrylamide moiety in said copolymeric product.