PAPER STRENGTHENING AGENT AND METHOD FOR ENHANCING PAPER STRENGTH USING THE SAME

PURPOSE:To obtain a paper strengthening agent, comprising cellulose or starch having amino and sulfone groups and capable of enhancing and improving the tensile, bursting strengths, etc. CONSTITUTION:This paper strengthening agent is obtained by reacting a tertiary amino or quaternary ammonium salt containing a beta-halogenated alkyl group, 3-chloro-2-hydroxypropyl group, etc., with cellulose or starch in the presence of an alkali, providing an aminated cellulose or starch, then sulfonating the produced aminated cellulose or starch, affording cellulose or starch containing amino and sulfonate groups. Enhancing effects on the tensile, bursting, terring strengths, etc., of the paper are improved by adding this paper strengthening agent into a pulp slurry. The substitution degrees of the amino and the sulfonate groups in the aminated and sulfonate cellulose or starch are preferably 0.02-0.25 and 0.2-2.0 respectively. The resultant aminated and sulfonated cellulose or starch is preferably added in an amount of 0.1+2wt.% based on the bone-dry weight of pulp thereto.