| 摘要 |
Reaction products of polymers of vinyl acetate and dialdehyde polysaccharides may be prepared by mixing emulsions of vinyl acetate polymers with aqueous dispersions of dialdehyde polysaccharides at a pH of 4 to 6. The vinyl acetate polymer may be polyvinyl acetate or a copolymer of vinyl acetate with vinyl propionate, vinyl 2-ethylhexoate, vinyl chloride, vinyl maleates, vinyl fumarates, acrylic esters or acrylonitrile, and may be partially hydrolysed, e.g. to contain 2 to 80% of polyvinyl alcohol. A plasticizer, e.g. acetyl triethylcitrate, and protective colloids, e.g. methyl cellulose, sodium carboxymethyl cellulose, hydroxyethyl cellulose, sodium and ammonium polyacrylates, polyvinyl alcohol, alginates and starches, may also be incorporated. The dialdehyde polysaccharide may be prepared by oxidizing starch, cellulose, dextrins and dextrans with periodic acid, and the aqueous dispersion thereof may be prepared by heating a slurry thereof in the presence of a buffer, e.g. sodium acetate, sodium bicarbonate or disodium phosphate. The products are less water-sensitive than the polymers from which they are prepared, and may be used in coating, making films, as binders for non-woven fabrics and in the paper industry. |
