| 摘要 |
<p>A resin is produced as a stable aqueous dispersion by the interaction of a dialdehyde polysaccharide and urea in an aqueous medium at a pH of 5-8 and a temperature of 30 DEG -70 DEG C. The urea may be added to a dialdehyde polysaccharide dispersion or the dialdehyde polysaccharide may be added to a urea solution. The mole ratio of urea to dialhyde polysaccharide polymer unit may be 0,5-2,0. The dialdehyde polysaccharide may be produced by the oxidation with periodic acid of maize or potato starch, dextran, algin, inulin, or cellulose. Oxidation may be 50-100% complete. The required pH may be maintained by the presence of a buffer in a concentration of 0,1-1,0 N. The buffer may be disodium phosphate, sodium bicarbonate, acetate, or p-toluene sulphonate, or triethanolamine. The resin dispersion may be concentrated to a solid content of 50-90% by evaporation. Gelling may be effected by acidifying and optionally heating. The acid may be hydrochloric, sulphuric, phosphoric, formic, acetic, oxalic, citric, or lactic acid. The gel may be dehydrated by drying or solvent exchange, e.g. with methanol. The resin may be incorporated in paper, paint, printing ink, or textile material or form a coating, e.g. for washable wallpaper. Examples are given. Specification 875,542 is referred to.</p> |
