| 摘要 |
1,051,434. Impact polymers. FOSTER GRANT CO. Inc. March 5. 1964 [March 5. 1963], No. 9446/64. Heading C3G. Impact polymers are prepared by a method comprising the steps of (a) dissolving a minor proportion of a natural rubber or a synthetic rubber derived from a conjugated diene in a major proportion of a liquid alkenyl aromatic monomer, (b) partially polymerizing the solution obtained to a pre-polymer of desired solids content, (c) admixing a low molecular weight alkenyl aromatic hydrocarbon polymer (i.e. such a polymer having a viscosity average molecular weight not exceeding 40,000) with the prepolymer and (d) further polymerizing the mixture so produced to a desired degree of conversion. The polymerization effected in steps (b) and (d) may be an emulsion or preferably, a bulk or suspension process. Additional liquid alkenyl aromatic monomer may be added in step (c). Suitable rubbers include natural crepe rubber, butadiene-styrene copolymers, in which the butadiene units may be stereoregular, butadiene-acrylonitrile copolymers, and polybutadiene or polyisoprene which may be stereoregulated. Styrene is preferred as the aromatic monomer, and the aromatic hydrocarbon polymer may be derived from styrene, vinyl toluene, vinylxyiene, ethyl vinylbenzene, isopropylstyrene and ethylvinyltoluene. In examples, the polymerization steps are effected using lauroyl peroxide as catalyst and dodecyl mercaptan as a molecular weight modifier. |
