| 摘要 |
1,006,284. Microcapsules. INTERNATIONAL BUSINESS MACHINES CORPORATION. Oct. 31, 1961 [Nov. 2, 1960], No. 38881/61. Heading B8C. Microcapsules composed of a cross-linked polyvinyl alcohol (P.V.A.) enclosing a liquid comprising or consisting of a low viscosity, low molecular weight non-polar solvent (e.g. hexane, octane, toluene, xylene, diethyl benzene, dibutylcarbitol, tritolyl phosphate, tributyl phosphate or silicones) are produced by forming an emulsion having a non-polar solvent phase and a polyvinyl alcohol in polar solvent phase and reacting the polyvinyl alcohol with a crosslinking agent at the interphase between the phases of the emulsion. This may be achieved by precipitating the P.V.A. from a water, glycerin, low molecular weight polyethylene glycol, aminoalcohol, amide or liquid ester solution by adddition of an organic or inorganic agent, e.g. a lower aliphatic alcohol, or inorganic salt such as sodium, ammonium or magnesium sulphate or by cooling or spray drying the emulsion and treating the P.V.A. with a cross-linking agent or catalyst, e.g. an acetal-forming agent or a polyfunctional compound having at least two alcohol-reactive radicals, e.g. phthalic anhydride, formaldehyde, acetaldehyde, p-phenyl diisocyanate, toluene diisocyanate and boric acid, dimethylol urea or tris-(hydroxymethyl) nitromethane. |
