Fabric sizing emulsion

A fabric sizing emulsion prepared by emulsion polymerization, at a temperature of from 40.degree. to 120.degree. C., of a reaction mixture consisting of from 25 to 50% by weight of vinyl acetate, an aqueous solution of polyvinyl alcohol having the property that a 1% aqueous solution thereof has a viscosity of 3 to 500 centipoises, said solution containing from 0.1 to 1% by weight, based on the weight of the reaction mixture, of a pH buffer salt effective to maintain the pH of the reaction mixture at from 4 to 8, said solution also containing an effective emulsifying amount of a non-ionic surface active agent having an HLB value of from 13 to 18 and selected from the group consisting of polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers and polyoxyethylene sorbitan fatty acid esters, said reaction mixture containing a polymerization initiator and cationic polymer selected from the group consisting of water-soluble cationic cellulose containing a quaternary ammonium cationic group and having a degree of cationic substitution of from 0.02 to 0.5, water-soluble cationic starch containing a quaternary ammonium cationic group and having a degree of cation substitution of from 0.02 to 0.5 and a cationic vinyl polymer, said reaction mixture containing from 0.2 to 3.0% by weight of said cationic polymer based on the weight of said emulsion, said cationic polymer having the property that a 1% aqueous solution thereof has a viscosity of from 5 to 1000 centipoises measured at 20.degree. C., the emulsion polymerization being continued until a vinyl polymer of said vinyl acetate is formed wherein said vinyl polymer contains from 0.01 to 0.15% by weight, based on said vinyl polymer, of cationic nitrogen atoms supplied by said cationic polymer.