| 摘要 |
Phototropic compositions comprise a solid solution of an inorganic heteropolyacid and a polymeric plastics material the molecule of which has side groups to form the solid solution with the said acid. Specified polymeric materials are vinyl alcohol/vinyl acetate copolymers, polyvinyl acetal and polyvinyl butyral. Cellulose acetate and cellulose acetate hydrogen phthalate are also said to be useful. Specified heteropolyacids are phosphomolybdic, silocotungstic and phosphotungstic acids. The compositions may also comprise cupric chloride. The compositions may be used in the preparation of windows, shields and eyeglasses for protection against intense radiation, and in the preparation of photographic images. Specification 1,008,538 is referred to.
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