| 摘要 |
1,253,113. Making microcapsules. FUJI PHOTO FILM CO. Ltd. 4 Aug., 1969 [3 Aug., 1968; 13 Sept., 1968; 17 Sept., 1968; 25 April, 1969 (2); 10 May, 1969. (2)], No. 39012/69. Heading B8C. Oil-containing microcapsules are prepared by emulsifying the oil in an aqueous hydrophilic colloid solution, adding thereto a solution of a second hydrophilic colloid of opposite charge and causing complex coacervation of the colloids, e.g. by dilution or alteration of pH, thereby to form embryo microcapsules, cooling the mixture to cause gelation of the capsule walls, adding an aqueous solution of an anionic polyelectrolyte and a hardening agent and adjusting the pH to within the range 9 to 11 to effect hardening of the capsule walls. Specified polyelectrolytes are: modified celluloses having #-1,4-glucosido bonds and having anionic functional groups, some or all the hydroxyl groups being esterified or etherified, e.g. carboxyalkyl celluloses, cellulose sulphate, cellulose phosphate and metal salts thereof; anionic starch derivatives, e.g. carboxyalkyl starches, starch sulphate, phosphate and xanthante; polygalactouronic acids, e.g. pectinic acid and pectins; condensates of naphthalene sulphonic acids and formalin; copolymers of vinylbenzene sulphonate with acryloylmorpholine, morpholinomethylacrylamide, acrylamide, vinylpyrrolidone and methoxy methyl acrylamide; derivatives of hydroxyethyl cellulose, e.g. the sulphate, phosphate and carboxymethyl ether; The hydrophilic colloids may be natural or synthetic, e.g. gelatine, casein, alginates, gum arabic, styrene-maleic anhydride copolymer and polyethylene-maleic anhydride copolymer, providing two having opposite charges are present. The oil may be any suitable natural or synthetic oil and may contain dissolved additives, e.g. dyes and dye precursors. |
