Sumitomo Chemical Company, Limited

Toshifumi Tamura

Yoshiharu Tatsukami

Fumio Fujita

Motonobu Furuta

Tsuneyuki Nagase

Shuji Kitamura

Katsuramaru Fujita

Toshihiro Ohnishi

Ichiki Murase

Masahiro Niwano

Masanori Fujimoto

Masato Ogura

Masaru Oota

Toshihiro Oonishi

An optical fiber with low attenuation of light transmission comprising a core and a cladding, wherein the core is made of a polymer comprising units of deuterated methyl methacrylate containing 10 to 40% of a methacrylic ester the ester moiety of which has an alicyclic hydrocarbon group of from 6 to 20 carbon atoms, and the cladding is made of a transparent polymeric material having a refractive index of at least 3% smaller than that of the core, which optical fiber has excellent heat and humidity resistance as well as good flexibility.

Plastic optical fiber resistant to heat and humidity

A plastic optical fiber comprising a core and a cladding, wherein the core is made a polymer comprising units of methyl methacrylate and of a methacrylate ester, the ester moiety of which has an alicyclic hydrocarbon of 8 to 20 carbon atoms, and the cladding is made of a fluorine-containing polymer comprising units of the formula: ##STR1## wherein R.sub.1 and R.sub.2 are each hydrogen or C.sub.1 -C.sub.3 alkyl, R.sub.f1 is fluorine or trifluoromethyl, an R.sub.f2 is C.sub.2 -C.sub.10 fluoroalkyl, which units (I) are derived from fluoroalkyl .alpha.-fluoroacrylate or trifluoromethacrylate, which has short- and long-time heat and humidity resistance as well as low attenuation of light transmission.

Plastic optical fiber

Highly dielectric organic compounds can be obtained by cyanoethylating a dihydroxyalkylate of a water-soluble polysaccharide or a derivative thereof with acrylonitrile.

Highly dielectric polysaccharides

The invention is to provide the methods for producing highly water-absorbable and water-retainable hydrogels having a large particle diameter together with a sufficient gel strength. The method is characterized by use of a specific dispersing agent in the water-in-oil type inverse phase suspension polymerization of an .alpha.,.beta.-unsaturated carboxylic acid and/or its alkali metal salt. Due to the high water-absorbability and water-retainability, along with the superior gel strength and the stable gel structure, the hydrogels of the invention enlarge the conventional range of usages.

Production of hydrogels

A method for producing a hydrophilic gel comprising polymerizing acrylic acid and/or methacrylic acid in the presence of polyvinyl alcohol to obtain a polymer (A) which is then subjected to neutralization followed by heat treatment or to heat treatment followed by neutralization, or polymerizing a neutralized product of acrylic acid and/or methacrylic acid in the presence of polyvinyl alcohol to obtain a polymer (B) which is then subjected to heat treatment, wherein said polymerization is carried out in an aqueous solution having a total concentration of acrylic acid and/or methacrylic acid or its neutralized product (the weight of the neutralized product is converted to the acid basis) and polyvinyl alcohol of 10 to 60% by weight, said heat treatment temperature is 50.degree. to 150.degree. C., and the weight ratio of polyvinylalcohol is acrylic acid and/or methacrylic acid or its salt (the weight of the neutralized product is converted to the acid basis) is 5 to 95: 95 to 5.

Method for preparing highly absorbent hydro-gel polymers

A method for the preparation of water-insoluble gels containing at least a hydroxyl group and a carboxylate group in molecules thereof which comprises saponifying copolymers comprising a vinyl ester component and an acrylic or methacrylic acid ester component or terpolymers comprising said two components and an ethylene component in the presence of an alkali catalyst and a solvent under conditions in which said copolymers or terpolymers are not dissolved.

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Takatsuki, Japan

Toshifumi Tamura