| 摘要 |
A dry non-adhesive powder comprises particles constituted by a core made up of 30-10% by wt. of elastomer and 70-0% of a hard polymer (i.e. a polymer not having rubbery characteristics whose latex can be coagulated to give a non-tacky powder), carrying an outer layer made up of a hard polymer is claimed which may be prepared by coagulating with agitation a latex whose solids comprise the above elastomer and adding to the coagulate, while agitating it, a latex of the above hard polymer containing a weight of that polymer which is 0.5-25% of the wt. of the solids from the first coagulated latex, permitting the second mentioned latex to coagulate on the former coagulate, separating the resultant solid from the aqueous phase and drying the solid. The elastomer may be a copolymer of vinyl acetate (45-95% by wt.) and ethylene, polybutadiene, a copolymer of butadiene with methyl methacrylate, styrene and/or acrylonitrile, polyisoprene and/or polychlorobutadiene. The hard polymer may be polyvinyl chloride, polymethyl methacrylate or polystyrene. The coagulant may be an aq. solution of Al2(SO4)3. 16H2O.ALSO:Particles comprising 30-100% by wt. of an elastomerand 70-0% of a hard polymer (i.e. a polymer not having rubbery characteristics whose latex can be coagulated to give a nontacky powder) which have been produced by coagulating with agitation a latex of the above particles, are coated by adding to the above coagulate while agitating it, a latex of the above hard polymer containing a weight of that polymer which is 0.5-25% of the wt. of the above particles, permitting the second mentioned latex to coagulate on the former coagulate, separating the resultant solid from the aqueous phase and drying the solid. The elastomer may be a copolymer of vinyl acetate and ethylene, polybutadiene, a copolymer of butadiene with methyl methacrylate, styrene and/or acrylonitrile, polyisoprene and/or polychlorobutadiene. The hard polymer may be polyvinyl chloride, polymethyl methacrylate or polystyrene. |
