Preparation and characterization of cationic silicone-acrylic latex surface sizing agent

• The surface sizing agent combined the advantage of A-173 and cationic SAE.
• The Cobb value decreased by 40% compared to the paper sized by pure starch.
• The ring crush index increased by 20% compared to the paper sized by pure starch.
• The surface sizing does not need the assistance of aluminum salts.

Series of cationic silicone-acrylic latexes used as surface sizing agents were prepared by using the semi-continuous emulsion polymerization of styrene and butyl acrylate in the presence of acrylamide, (2-(methacryloyloxy) ethyl) trimethyl ammonium chloride and vinyltriisopropoxysilane (A-173). The structure and properties of the cationic silicone-acrylic latexes were examined by Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS) and differential scanning calorimetry (DSC). The latexes were subsequently used as surface sizing agents, and the sizing properties were evaluated using scanning electron microscope (SEM), a video-based contact angle measuring device and a Cobb absorbency tester. It was observed that the cationic silicone-acrylic latexes produced possessed remarkable chemical stability. The surface sizing agent containing this type of cationic silicone-acrylic latex, even in the absence of aluminum salt, was excellent in improving the water resistance and mechanical properties of the corrugated paper. Compared with that of the pure anionic cassava starch sizing agent, the Cobb value of the sizing agent that consisted of 99.6% anionic cassava starch and 0.4% cationic silicone-acrylic latex, in which the dosage of vinyltriisopropoxysilane was 4%, decreased by 40%, and the ring crush index increased by 20%.

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