Hitachi Chemical Company, Ltd.

Hitachi, Ltd.

Toshio Akima

Takayuki Saito

Akihiro Kobayashi

Toshiyuki Fujita

Makoto Saitou

Hiroshi Nakaguki

Tetsuya Katou

Makoto Kunimi

Hiromasa Kawai

Takashi Morinaga

Yutaka Hosoi

Hiromu Miyajima

Mitsuharu Kato

A process of producing expandable styrene resin particles, wherein in suspension polymerization of styrene monomers, the concentration of oxygen in a reaction vessel is kept low at least in a late stage of the polymerization, and the resulting styrene resin particles are impregnated with an expanding agent before or after completion of the polymerization. Preferably, at a polymerization rate of 60% or higher, the concentration of oxygen in the reaction vessel is kept at 7 volt % or lower. When additional styrene monomers are added during the polymerization, they are added and adsorbed to styrene resin particles in the course of polymerization while the concentration of oxygen is kept low. By this method, the particles whose internal portion has a low molecular weight and surface portion has a high molecular weight are obtained. A foamed article produced from the particles has high strength and a good appearance.

Expandable styrene resin particles, expandable beads, and foamed article

A process of producing expandable styrene resin particles, wherein in suspension polymerization of styrene monomers, the concentration of oxygen in a reaction vessel is kept low at least in a late stage of the polymerization, and the resulting styrene resin particles are impregnated with an expanding agent before or after completion of the polymerization. Preferably, at a polymerization rate of 60% or higher, the concentration of oxygen in the reaction vessel is kept at 7 vol % or lower. When additional styrene monomers are added during the polymerization, they are added and adsorbed to styrene resin particles in the course of polymerization while the concentration of oxygen is kept low. By this method, the particles whose internal portion has a low molecular weight and surface portion has a high molecular weight are obtained. A foamed article produced from the particles has high strength and a good appearance.

In a process for producing a methacrylic acid ester by subjecting methyl methacrylate and an alcohol to a transesterification reaction in the presence of a catalyst and a polymerization inhibitor, the filtration time of catalyst and the like can be shortened by making a total water content in the catalyst, alcohol and methyl methacrylate 1000 ppm or less, or the generation of large bubbles during the reaction can be prevented by adding the starting alcohol to the reaction system at the alcohol conversion of 40% or more, or high catalytic activity is obtained even if a secondary or tertiary alcohol is used as a starting material by using as a catalyst that obtained by drying lithium hydroxide monohydrate with heating, these effects being also obtained by combining individual conditions.

Process for producing methacrylic acid esters

Methacrylate esters of alcohols having an ether linkage and/or an alicyclic ring can be obtained with no trouble of coloration or polymer formation during the production and for the product. An alcohol having an ether linkage and/or an alicyclic ring is treated with an alkaline substance, and the treated alcohol is caused to react with methyl methacrylate for a transesterification reaction in the presence of an alkaline substance.

Method for production of methacrylate ester

A polymer obtained by polymerizing tricyclo[5.2.1.0.sup.2,6 ]deca-8-yl acrylate or methacrylate in an amount of 100-5% by weight with one or more copolymerizable unsaturated monomers in an amount of 0 to 95% by weight is excellent in transparency, moisture resistance, and heat resistance and is suitable as a material for optical elements.

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Ichihara, Japan

Toshio Akima