Polymeric organic acids, their preparation and their use in detergents and cleansers

Claim 1

A continuous process for the preparation of a water-soluble organic acid copolymer, having a K value between 18-33, which exhibits scale inhibiting properties when used in low phosphate detergents and calcium-binding capability and detergent action when used as a builder comprising the following steps: A. copolymerizing in two polymerization zones arranged in series a comonomeric mixture consisting essentially of: (1) 60-85% by weight of acrylic acid, methacrylic acid or combinations thereof, (2) 1-5% by weight of at least one monomer devoid of acid groups being copolymerizable with monomer (1) selected from the group consisting of vinyl acetate, n-butyl acrylate, 2-ethylhexyl acrylate, hydroxypropyl acrylate, styrene, N-vinylpyrrolidone, vinylisobutyl ether and mixtures thereof, and (3) 10-40% by weight of maleic anhydride, the total of components (1), (2) and (3) being 100%, under continuous mass polymerization conditions with thorough mixing of the components in the absence of a solvent in the presence of from 0.1-5% by weight, based on the total amount of monomer components, of a free radical initiator at a temperature of from 200°-400° C. for 5 to 30 minutes and at a superatmospheric pressure ranging from 1 to 200 bar, thereby producing the molten copolymer; B. discharging said molten copolymer from the reactor, while simultaneously introducing into the reactor said comonomeric mixture, wherein the amount of said molten copolymer discharged from said reactor at any time is equal to the amount of said comonomeric mixture simultaneously introduced into the polymerization medium in said polymerization zones; C. at least partially neutralizing said discharged copolymer; and D. recovering said at least partially neutralized, water-soluble organic acid polymer having a K value between 18-33.