Tokuyama Soda Kabushiki Kaisha

Tokuyama Corporation

Masaki Noritake

Genji Taga

Shigeki Yuasa

Hua-Min Zhang

Masahiro Nakamura

Masami Enokuchi

An inorganic composition comprises (A) 60 to 99% by weight of spherical inorganic oxide particles having a mean particle diameter greater than 0.1 .mu.m but not greater than 1 .mu.m, and (B) 40 to 1% by weight of inorganic oxide fine particles having a mean particle diameter not greater than 0.1 .mu.m, wherein a volume of micro pores due to strongly aggregated particles having pore diameters not smaller than 0.08 .mu.m is not greater than 0.1 cc per gram of the inorganic composition. The inorganic composition, when mixed with a polymerizable monomer and a catalyst, provides a composite useful for dental applications which has excellent surface smoothness, can be polished in a short time, exhibits improved bending strength, compressive strength, surface hardness and wear resistance and causes little wear on an antagonistic tooth.

Inorganic composition

Disclosed is a process for the preparation of an anorthite sintered body, which comprises preparing a formed body of at least one powder selected from the group consisting of (i) a calcium type zeolite having an SiO.sub.2 /Al.sub.2 O.sub.3 molar ratio lower than 3, (ii) an amorphous calcination product obtained by calcining said calcium type zeolite and (iii) a mixture of said calcium type zeolite or said amorphous calcination product and an alkaline earth metal compound, and sintering the formed body at a temperature lower than 1000.degree. C.

Process for preparation of anorthite sintered body

An alkaline earth metal aluminosilicate sintered body is obtained by molding a starting mixture of a zeolite having an alkaline earth metal form and an SiO.sub.2 /Al.sub.2 O.sub.3 molar ratio not higher than 3.0 and a boron compound such as boron oxide, and firing the molded body at a temperature lower than 1,000.degree. C. An amorphous calcination product formed by calcining the zeolite may also be used in the starting mixture with the boron compound. This process allows the range of firing temperatures suitable for formation of a sintered body to be varied over a range of from about 50.degree. to 150.degree. C. or more while also allowing lower firing temperatures than in the absence of the boron compound to be used while still obtaining the desired densified sintered body.

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Tokuyama, Japan

Masaki Noritake