Composition for increasing wet strength of paper including water-soluble blocked urethane prepolymers

摘要

For use as a wet strength agent, a water-soluble blocked urethane prepolymer having a hydrophilic group and a blocked isocyanate group is combined with a cationic charge-adjusting agent. The adsorption and retention of the water-soluble blocked urethane prepolymer to cellulosic fiber are promoted by virtue of the cationic charge adjusting agent when the wet strength agent is added to a paper-making stock.