Patent ID: 6087457
Filing Date: 2000-07-11
Classification: D21H

Abstract:
A method of surface sizing cellulose based products in order to increase resistance to penetration by aqueous liquids which comprises applying to the surface of said products a sizing composition which comprises an aqueous dispersion of a copolymer obtained by free-radical emulsion polymerization of a monomer mixture comprising(a) from 70 to 99% by weight of(a1) at least one monomer selected from the group consisting of styrene and derivatives thereof; and(a2) at least one monomer selected from the group consisting of esters of ethylenically unsaturated carboxylic acids and alkanols; wherein the monomer of (a1) comprises at least 50% by weight of (a); and(b) from 0.5 to 15% by weight of at least one monomer selected from the group consisting of ethylenically unsaturated carboxylic acids and salts thereof, and ethylenically unsaturated sulfonic acids and salts thereof; and(c) from 0.5 to 15% by weight of other ethylenically unsaturated copolymerizable monomers comprising at least one monomer containing a hydroxyl group, wherein the sum of the percentages of (a)+(b)+(c) is 100, wherein said polymerization is conducted in the absence of a protective colloid effective amount of starch.