Synthesis of cationic styrene-acrylic acid ester copolymer emulsion for paper sizing

Surface sizing is an effective way to increase paper's water-resistance and printability. The purpose of this study was to study synthesis process to develop an efficient cationic styrene-acrylic acid ester emulsion (SAE) for the surface sizing of paper. Dimethylaminoethyl methacrylate methyl chloride (DMC) was used as the cationic monomer, and cationic starch or native starch was used as the emulsion stabilizer to copolymerize with styrene and butyl acrylate. The results indicated that the SAE synthesized with cationic starch and DMC had a high cationic charge density and a high DMC conversion rate. Paper sized with the cationic SAE had higher surface strength and lower Cobb value than the paper sized with other surface sizing agents such as, anionic SAE, and cationic or oxidized starch. Scanning electron micrographs revealed that the paper sized with a combination of oxidized starch and cationic SAE had smoother surface morphology when compared to the paper sized with oxidized starch alone, or with oxidized starch and anionic SAE.