| 摘要 |
1,141,300. Microcapsules. NATIONAL CASH REGISTER CO. 8 March, 1967 [4 April, 1966], No. 10913/67. Heading B8C. [Also in Division B2] Liquid-containing capsules having walls of hardened polymeric material are coated by preparing a slurry of the capsules in a liquid in which the capsule wall-material is swellable but not soluble, adding to the slurry a finely divided solid particulate material which is insoluble in the liquid of the slurry, draining the free liquid from the slurry causing the solid particulate material to deposit on and around the swollen capsules, and drying the mass of capsules by evaporation of the residual liquid to shrink the capsule walls which thereby partially entrap the adherent solid particulate material. The capsules are prepared from a liquid dispersion of the capsule wall forming and nucleus materials. The capsules may contain a curable liquid resin e.g. a polysulphide resin, and the solid particulate material may be a curing agent for the resin e.g. at least one of manganese dioxide, tellurium dioxide, antimony trioxide and lead dioxide. In Example 1 the capsules are prepared from a liquid dispersion of acid-extracted pig skin gelatine and gum arabic as capsule wall-forming material and liquid polysulphide resin as nucleus material hardened with glutaraldehyde, and manganese dioxide is added to a slurry of the capsules in water. In example 2 the capsules contain a liquid viz. toluene which does not co-react with the applied material viz. magnesium silicate. |
