| 摘要 |
1,197,551. Treating microcapsules. NATIONAL CASH REGISTER CO. 20 Jan., 1969 [29 Jan., 1968], No. 3075/69. Heading B8C. [Also in Division C3] Microcapsules having walls of hydrophilic polymeric material are treated to reduce their permeability to fluids by effecting free radical polymerization of a monomer within the interstices of the wall material whereby a polymer is formed and permeates the wall material. The wall material may be any hydrophilic polymer, e.g. gelatin, gum arabic, carageenan, polyvinyl pyrrolidone, poly vinyl alcohol, poly acrylate or maleic anhydride co-polymers which contain chemically bound or complexed transition metal ions (Fe, Co, Ni, Cu, Cr (III), U or V (III or IV) which are thought to be necessary for the reaction to occur. The monomer (e.g. a free-radical polymerizable olefin, acrylate or vinyl-type monomer) may be introduced into a liquid in which the capsules are suspended together with an initiator (e.g. a peroxide, azo compound or peracid) and the conditions adjusted so that polymerization occurs, the transition metal ions inducing the reaction within the capsular wall material. |
