PRODUCTION OF PARTIALLY NEUTRALIZED POLYCARBOXYLIC ACID, AND PARTIALLY NEUTRALIZED POLYCARBOXYLIC ACID

摘要

PROBLEM TO BE SOLVED: To obtain the subject polycarboxylic acid that reduces unpolymerized monomer, keeps uniform viscosity and pH, high in quality, and is useful as a thickener for poultice, by carrying out partial neutralization and polymerization of unsaturated carboxylic acid in a non-metal vessel. ;SOLUTION: The partial neutralization and polymerization of an α,β-unsaturated carboxylic acid of the formula [R is H, COOH; R₁ is H, CH₃; R₂ is H or an alkali metal, for example, sodium] (for example, acrylic acid) or its salt is carried out in a non-metal (for example, made of Teflon) or a metal vessel lined with a non-metal substance as poly(vinyl chloride) to give the objective polycarboxyic acid. In an embodiment with an acrylic acid polymer, 40-60% of the carboxyl groups in the polymer is in the sodium salt form, the viscosity is 500-800Pa.s, the total of acrylic acid and its sodium salt is ≤0.5%, the pH of the 0.2% aqueous solution of the polymer is 6-7, it is substantially free from insoluble gel and contains ≤0.8ppm heavy metal content.;COPYRIGHT: (C)1998,JPO