Kyowa Gas Chemical Industry Company, Ltd.

Kuraray Co., Ltd.

Haruo Nagai

Hiroshi Uehara

Kunikazu Nunokawa

Takashi Nishida

Kazuo Itoi

Yoichi Ninagawa

Yutaka Omura

Kazuhiro Sato

Tetsuo Suzuki

A methacrylic resin molding material, comprising a partially cross-linked polymer gel obtained by partially polymerizing a mixture comprising (A) a resin raw material selected from the group consisting of monomeric alkyl methacrylates, .alpha., .beta.-ethylenically unsaturated monomer mixtures formed preponderantly of alkyl methacrylates and a syrup containing at least one of said monomers and at least one of the polymers thereof and (B) 4 to 150 parts by weight of a cross-linking agent based on 100 parts by weight of said resin raw material in the presence of a polymerization initiator, whereby a cross-linked polymer is formed with the aid of said cross-linking agent and said polymerization initiator to the extent that increase of the polymer formed thereby reaches 4 to 62% by weight over the polymer content of said mixture with the total polymer content kept from exceeding the upper limit of 62% by weight said molding material being recovered from the polymerization system as a non-sticky, easy-handled gel-like material which has shape-retaining properties, but which, on the application of shear stress, at normal room temperature or at an elevated temperature, is enabled to flow, and preserved for use in the manufacture of shaped articles.

Methacrylic resin molding material and method for production thereof

A method for producing a lead containing monomer composition comprising reacting a mixture comprising (1) at least one monomer selected from the group consisting of alkyl methacrylate having 1-4 carbon atoms in an alkyl group, hydroxyalkyl acrylate, hydroxyalkyl methacrylate and styrene, (2) acrylic or methacrylic acid, (3) an organic acid having the general formula: R.sub.1 COOH, wherein R.sub.1 is hydrocarbon residue having 5-20 carbon atoms and optionally (4) an organic acid having the general formula: R.sub.2 COOH, wherein R.sub.2 is hydrocarbon residue having 2-4 carbon atoms with lead monoxide. The composition is polymerized to obtain a radiation shielding polymer.

Method for producing a lead containing monomer composition and a

A radiation shielding material of a composition containing a polymer comprising (A) at least one essential monomer selected from the group consisting of alkyl methacrylate having 1 - 4 carbon atoms in an alkyl group, hydroxyalkyl acrylate, hydroxyalkyl methacrylate and styrene and (B) lead acrylate or lead methacrylate, and a lead carboxylate represented by the general formula: (RCOO).sub.a Pb, a being an integer equal to the valency of lead and R representing a saturated or unsaturated hydrocarbon residue having 5 - 20 carbon atoms, wherein the ratio x (% by weight) of the lead acrylate or lead methacrylate to the total constituent monomer in the polymer and the compounding ratio y (parts by weight) of the lead carboxylate to 100 parts by weight of said total monomer in said composition satisfy any one of the following three formulas I, II and III:

Radiation shielding material and a process for producing the same

Novel 2,6,10,15,19,23-hexamethyltetracosane-10,15-diol derivatives. Such derivatives are prepared by hydrogenation of 2,6,10,15,19,23-hexamethyltetracosa-11,13-diyne-10,15-diol derivatives and used as starting materials for preparing squalane.

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Nakajo, Japan

Haruo Nagai