| 摘要 |
<p>1,138,570. Microcapsules. NATIONAL CASH REGISTER CO. 22 Sept., 1967 [10 Oct., 1966], No. 43157/67. Heading B8C. Microcapsules, each consisting of a wall of polymeric material enclosing a solid or liquid core particle, are made by dispersing the core material in a manufacturing liquid from which there is caused to separate a polymer-rich phase comprising a polymeric complex composed of two kinds of polymeric material joined by hydrogen bonding which coats the dispersed particles to form microcapsules in the usual way. Both types of polymer may be present in the initial manufacturing liquid, from which they are induced to separate by changing conditions, e.g. the pH may be changed or a solution of one type may be added to the system already containing the other under conditions allowing immediate formation of the complex and phaseseparation thereof. The polymer pair should comprise at least one "Hydrogen bonding acid" e.g. polyacrylic acid, poly(methacrylic acid), poly(vinyl alcohol), poly(vinyl pyrrolidone), methyl cellulose, carboxymethyl cellulose, poly- (styrene co - maleic anhydride), poly(vinylmethylether co-maleic anhydride) or poly(ethylene co-maleic anhydride) and at least one "Hydrogen bonding base" e.g. poly(ethylene oxide), poly(ethylene oxide co-propylene oxide), poly(propylene oxide), poly(vinyl pyrrolidone), poly(vinyl alcohol), poly(ethylene glycol), poly- (acrylic acid) or poly(methacrylic acid) (the designations "acidic" and "basic" being relative not absolute). The capsules may be dried in the usual way. Examples relate to the encap. sulation of stainless steel particles, ammonium dichromate and lemon oil.</p> |
