Process for reforming styrene resins

The styrene resins are graft polymerized with vinylidene chloride using ionizing radiations of high transmission to minimize the gas permeability of the styrene resins. The process comprises graft polymerizing vinylidene chloride on the styrene by irradiation with ionizing radiations at a temperature lower than the softening point of the styrene resins under a pressure of 300 mmHg of the vinylidene chloride vapor. The styrene resin materials may be a monomer, a polymer or a copolymer; the resins such as styrene, alpha methyl styrene, vinyl toluene, HI resin and ABS resin. Ionizing radiations may be gamma-rays in the range between 0.5 and 5 MeV, gamma-rays from a Cs-137 source, or high energy X-rays obtained from the bombardment of a heavy metal target with electron beams. In one embodiment, a film 0.06mm thick, made of 0.874 g of polystyrene, suspended in a glass ampoule, de-gassed under a pressure of 10-4mmHg or above, was heated at 240C. Then the vinylidene chloride vapor was introduced into the ampoule at 210 mmHg and irradiated with gamma-rays from a Co-60 source at a dose rate of 0.6 x 104 R/hr for 4 hrs. The pressure of the vinylidene chloride was maintained constant during irradiation. The film was removed from the ampoule after irradiation, washed with methanol and dried in vacuum. The weight of the product was 0.9480 gram and its degree of graft polymerization was 84% by weight. The gas permeability was 0.27 x 10-10 cc/cm.sec.cmHg for nitrogen and 1.7 x 10-10 cc/cm.sec.cmHg for oxygen. (Iwakiri, K.)