POLYMER COMPOSITION FOR WATER RETENSION AND ACTIVATION OF FLUORESCENT WHITENING AGENT, PAPER COATING COLOR, AND SHEET OF COATED PAPER THUS OBTAINED

摘要

PROBLEM TO BE SOLVED: To obtain a polymer composition which provides activation of a liquid and stable fluorescent whitening agent, water retension, and viscosity control of a paper coating color by blending a polyvinyl alcohol having specific values of physical properties with a water-soluble polymer at neutral or alkaline pH. SOLUTION: A polyvinyl alcohol(PVA) used in a polymer composition has an Ostwald viscosity not more than 15 mPa.s (corresponding to a degree of polymerization of not more than 600) and a molar hydrolysis of 70-100% measured on the basis of the ester index (DIN53401), (corresponding to 30-0 molar % of a vinyl acetate structure). A water-soluble polymer used in the polymer composition is a dispersed copolymer containing an acid group, particularly a carboxyl group, and at least 20 wt.% (20-75 wt.%) of a monomer, and concretely, a water-soluble polyurethane, a homopolymer or copolymer of a carboxylic acid is cited. The PVA is preferably used in an amount above 20 wt.% of the composition.