| 摘要 |
1,177,440. Microcapsules. NATIONAL CASH REGISTER CO. 15 July, 1968 [21 Aug., 1967], No. 33566/68. Heading B8C. Microcapsules are made by dissolving a filmforming polymeric material in a first liquid, bringing this liquid together with a second liquid which is a non-solvent for the polymeric material in such a way that a dispersion of the solid or of one of the liquids in the other liquid is formed and the polymeric material is precipitated at the interface, thereby to encapsulate the dispersed phase. Alternatively, a particulate solid which is soluble in the first liquid or which has been treated with a liquid miscible with the first liquid is dispersed in the polymer solution, whereby precipitation of the polymer on the particles is effected. Thereafter, the microcapsules may be removed from the residual liquid and dried. Suitable liquid pairs are water and acetone, ethanol, dimethylformamide tetrahydrofuran or dimethylacetamide and acetone and heptane or cyclohexane. Specified wallforming polymeric materials are polyethyleneimine, poly-(vinyl methyl ether-co.maleic anhydride), polyvinylpyrrolidone, poly-(styrene-co-maleic anhydride), polyacrylic acid copolymers and polyvinylchloride copolymers. Examples are given in which the polymer is in the dispersed or continuous phase, in both phases and in a continuous phase in which is dispersed silica gel particles containing absorbed acetic acid. |
