Production of acrylate interpolymer aqueous latices

Claim 1

A PROCESS FOR PRODUCING AN AQUEOUS INTERPOLYMER LATEX, THE SAID INTERPOLYMER CONSISTING OF, IN POLYMERIZED FORM, (1) ABOUT 25-45% BY WEIGHT OF AT LEAST ONE ESTER SELECTED FROM THE CLASS CONSISTING OF ALKYL ESTERS OF ACRYLIC ACID AND METHACRYLIC ACID, THE ALCOHOL MOIETIES OF WHICH CONTAIN 5-18 CARBON ATOMS, (2) ABOUT 1-5% BY WEIGHT OF AT LEAST ONE UNSATURATED ACID SELECTED FROM THE CLASS CONSISTING OF ACRYLIC ACID, METHACRYLIC ACID, CINNAMIC ACID, ATROPIC ACID AND CROTONIC ACID (3) ABOUT 50-74% BY WEIGH TOF AT LEAST ONE HARDENING COMONOMER OF THE GROUP CONSISTING OF MONOVINYLIDENE AROMATIC HYDROCARBONS, HALOGENATED DERIVATIVES OF MONOVINYLIDENE AROMATIC HYDROCARBONS AND ALKYL ESTERS OF METHACRYLIC ACID, THE ALCOHOL MOIETIES OF WHICH CONTAIN 1-3 CARBON ATOMS, SAID INTERPOLYMER LATEX BEING PRODUCED BY A CATALYTIC EMULSION POLYMERIZATION PROCESS COMPRISING THE STEPS OF PROVIDING AT POLYMERIIZATION TEMPERATURE OF ABOUT 30150*C. AN AQUEOUS MEDIUM CONTAINING AN EMULSIFIER SELECTED FROM THE CLASS CONSISTING OF ANIONIC AND NONIONIIC EMULSIFIERS, AND A MAJOR PORTION OF THE WATER REQUIREMENT FOR SAID LATEX, AND WHILE MAINTAINING THE SAID TEMPERATURE ADDING SLOWLY AND IN SEQUENCE TO SAID AQUEOUS MEDIUM AT SUBSTANTIALLY CONSTANT RATE A FIRST MONOMER CHARGE AND A SECOND MONOMER CHARGE, SAID FIRST MONOMER CHARGE BEING CONSTITUTED ESSENTIALLY OF HARDENING COMONOMER AND BEING EQUAL TO 10-50% BY WEIGHT OF THE TOTAL MONOMER CHARGE, SAID SECOND MONOMER CHARGE COMPRISING THE REMAINDER OF THE MONOMERS AND WHEREIN AT LEAST 10% BY WEIGHT OF SAID SECOND MONOMER CHARGE CONSISTS OF HARDENING COMONOMER, BOTH OF SAID MONOMER CHARGES BEING ACCOMPANIED BY ADDITION AT CONSTANT RATE OF AN AQUEOUS COMPOSITION CONTAINING A FREE RADICAL POLYMERIZATION CATALYST AND THEREAFTER MAINTAINIING THE RESULTANT REACTION MIXTURE AT POLYMERIZATION TEMPERATURE UNTIL POLYMERIZATION IS SUBSTANTIALLY COMPLETE.