Continuous process for the preparation of an acrylic acid-methyl acrylate copolymer in a tubular reactor

Claim 1

A method for preparing copolymers of vinyl carboxylic acids and lower alkyl acrylates selected from the group consisting of methyl acrylate and ethyl acrylate, said vinyl carboxylic acids having the formula prior to polymerization: ##STR2## wherein R is H or CH 3 and A is selected from the group consisting of hydrogen, ammonium or alkali metal ions, said method comprising the steps of polymerizing an aqueous solution of the vinyl carboxylic acid with said lower alkyl acrylate in a tube reactor at a pressure of between 50-350 psig, said pressure being sufficient to maintain the reactants in a liquid state in the presence of a free radical catalyst while maintaining the conditions of the reaction within the limits set forth below: ______________________________________ I. Monomer solids 20-50% by weight II. Initiation temperature 80-180° F. (°F.) III. Monomer pH 1.0-6.0 IV. Initiator concentration 2.0-12% by weight (based on monomer) V. Vinyl carboxylic acid-lower 60/40-95/5 alkyl acrylate weight ratio VI. Residence time 1-15 minutes ______________________________________ said copolymer of vinyl carboxylic acid and lower alkyl acrylate having a molecular weight of from 3,000-300,000.

Claim 2

A method for preparing copolymers of vinyl carboxylic acids and lower alkyl acrylates selected from the group consisting of methyl acrylate and ethyl acrylate, said vinyl carboxylic acids having the formula prior to polymerization: ##STR2## wherein R is H or CH 3 and A is selected from the group consisting of hydrogen, ammonium or alkali metal ions, said method comprising the steps of polymerizing an aqueous solution of the vinyl carboxylic acid with said lower alkyl acrylate in a tube reactor at a pressure of between 50-350 psig, said pressure being sufficient to maintain the reactants in a liquid state in the presence of a free radical catalyst while maintaining the conditions of the reaction within the limits set forth below: ______________________________________ I. Monomer solids 20-50% by weight II. Initiation temperature 80-180° F. (°F.) III. Monomer pH 1.0-6.0 IV. Initiator concentration 2.0-12% by weight (based on monomer) V. Vinyl carboxylic acid-lower 60/40-95/5 alkyl acrylate weight ratio VI. Residence time 1-15 minutes ______________________________________ said copolymer of vinyl carboxylic acid and lower alkyl acrylate having a molecular weight of from 3,000-300,000.