TOUGHENED THERMOPLASTICS

摘要

1401086 Grafted polydiorganosiloxanes DOW CORNING CORP 30 April 1973 [1 May 1972] 20373/73 Heading C3G A toughened thermoplastic composition having values for notched Izod impact strengths in foot pounds per inch of notch, wherein the notch is 45 degrees and 0À1 inch deep, at least 35% greater than an unmodified thermoplastic composition wherein the thermoplastic in the toughened composition is the same as in the unmodified composition, comprises a continuous matrix of a plastic wherein the unpolymerized monomeric compound is at least one compound selected from styrene, methyl methacrylate, a ring-substituted alkyl styrene, or a mixture thereof, or a mixture of at least one of styrene, methyl methacrylate, a ring-substituted alkyl styrene with at least one monomer selected from acrylonitrile, alpha-methylstyrene, maleic anhydride, methacrylonitrile, acrylic acid, vinyl halides or vinylidene halides, having dispersed therein gelled particles which have a diameter of from 0À05 to 200 microns, where the geometric mean diameter is from 0À3 to 20 microns, the gelled particles comprising a polydiorganosiloxane of the formula having polymeric species derived from the above defined monomeric compound grafted thereto through the R11 radical, where R is a monovalent radical having a maximum of 18 carbon atoms and selected from a hydrogen atom, an alkyl, haloalkyl, aryl, haloaryl or aralkyl group, wherein at least 50% of the R radicals are methyl or ethyl radicals, X is a terminal group selected from a R1R 2 SiO- group or a hydroxyl group, X1 is selected from a R1R 2 Sigroup or a hydrogen atom, R1 is as defined for R or a vinyl or allyl group, R11 is vinyl or allyl, m and 1-m represent the mole ratio of each type of diorganosiloxane unit in the polydiorganosiloxane, respectively, and m has a value from 0À75 to 0À85, x represents the total number of diorganosiloxane units in the polydiorganosiloxane and has a value sufficient to provide a Williams plasticity of at least 0À060 inch, as determined on the unreacted polydiorganosiloxane, the polydiorganosiloxane being present in an amount of from 1 to 15% by weight, based on the total combined weight of the thermoplastic and the polydiorganosiloxane, the toughened thermoplastic composition being prepared by polymerizing with agitation at 35‹ to 200‹ C. by free radical means, the monomeric compound described above in which the unreacted polydiorganosiloxane is dispersed. Examples are given in which a hydroxyl - terminated methylvinylsiloxane/ dimethylsiloxane copolymer is (a) dissolved in styrene and polymerization is carried out in bulk and then in aqueous suspension, the product being blended with polystyrene; (b) grafted as in (a), except that the monomers used are styrene and acrylonitrile, or styrene, methyl methacrylate and alpha-methylstyrene; (c) grafted with styrene and acrylonitrile in aqueous emulsion.