High-dispersion sol or gel of monoclinic zirconia supermicrocrystals and production of the same

Claim 2

A high-dispersion product which comprises: a sol or gel of isolated monoclinic zirconia microcrystals dispersed in an aqueous solution without agglomeration at a concentration of 0.1 to 1 mol/liter, wherein said monoclinic zirconia microcrystals have uniform size, and a diameter or width smaller than 100 angstroms, and wherein said sol or gel is translucent.

Claim 3

The high-dispersion product as defined in claim 1, wherein said product is a sol.

Claim 4

The high-dispersion product as defined in claim 1, wherein said product is a gel.

Claim 5

A process for producing a high-dispersion product which is a sol or gel of monoclinic zirconia microcrystals which comprises: adding water to hydrated salt crystal composed mainly of zirconyl chloride in an amount of 400 ml or less per 1 gram atom of zirconium so as to produce a mixture; subjecting said mixture to hydrothermal treatment in a sealed container at more than 130° C. for more than 24 hours to produce a white pasty product; diluting said white pasty product with water so that the zirconium concentration decreases below 1 mol/liter to produce a diluted product; adjusting the pH of said diluted product to 3 to 7; and concentrating said diluted product to obtain a high-dispersion product which comprises a sol or gel of isolated monoclinic zirconia microcrystals dispersed in an aqueous solution without agglomeration at a concentration of 0.1 to 1 mol/liter, wherein said monoclinic zirconia microcrystals have uniform size, and a diameter or width smaller than 100 angstroms, and wherein said sol or gel is translucent.

Claim 6

A process for producing a high-dispersion product which is a sol or gel of monoclinic zirconia microcrystals which comprises: adding water to hydrated salt crystal composed mainly of zirconyl chloride in an amount of 400 ml or less per 1 gram atom of zirconium so as to produce a mixture; subjecting said mixture to hydrothermal treatment in a sealed container at more than 130° C. for more than 24 hours to produce a white pasty product; diluting said white pasty product with water so that the zirconium concentration decreases below 1 mol/liter to produce a diluted product; adjusting the pH of said diluted product to 3 to 7; and concentrating said diluted product to obtain a high-dispersion product which comprises a sol or gel of isolated monoclinic zirconia microcrystals dispersed in an aqueous solution without agglomeration at a concentration of 0.1 to 1 mol/liter, wherein said monoclinic zirconia microcrystals have uniform size, and a diameter or width smaller than 100 angstroms, and wherein said sol or gel is translucent.

Claim 7

The process as defined in claim 4, wherein a high-dispersion sol is produced.

Claim 8

The process as defined in claim 4, wherein a high-dispersion gel is produced.

Claim 9

The process as defined in claim 4, wherein said water is in an amount of 40 to 350 ml per 1 gram atom of zirconium.

Claim 10

The process as defined in claim 4, wherein said mixture is subjected to hydrothermal treatment at 180° to 270° C. for 1 to 10 days.

Claim 11

The process as defined in claim 4, wherein said white pasty product is diluted so that the zirconium concentration decreases to 0.1 to 0.5 mol/liter.

Claim 12

The process as defined in claim 4, wherein said obtained high-dispersion product is a sol and wherein said sol is concentrated by heating in the range of 80° to 100° C. to produce a gel.

Claim 13

A process for producing a high-dispersion product which is a sol or gel of monoclinic zirconia microcrystals which comprises: subjecting to hydrothermal treatment in a sealed container an aqueous solution which contains more than 1.5 mol/liter of zirconium salt or hydroxide based on zirconium concentration and having such a composition as to produce more than 3 mol/liter of hydrochloric acid after hydrolysis, said hydrothermal treatment being conducted at more than 130° C. for more than 24 hours so as to produce a white pasty product; diluting said white pasty product with water so that the zirconium concentration decreases below 1 mol/liter to produce a diluted product; adjusting the pH of said diluted product to 3 to 7; and concentrating said diluted product to obtain a high dispersion product which comprises a sol or gel of isolated monoclinic zirconia microcrystals dispersed in an aqueous solution without agglomeration at a concentration of 0.1 to 1 mol/liter, wherein said monoclinic zirconia microcrystals have uniform size, and a diameter or width smaller than 100 angstroms, and wherein said sol or gel is translucent.

Claim 14

A process for producing a high-dispersion product which is a sol or gel of monoclinic zirconia microcrystals which comprises: subjecting to hydrothermal treatment in a sealed container an aqueous solution which contains more than 1.5 mol/liter of zirconium salt or hydroxide based on zirconium concentration and having such a composition as to produce more than 3 mol/liter of hydrochloric acid after hydrolysis, said hydrothermal treatment being conducted at more than 130° C. for more than 24 hours so as to produce a white pasty product; diluting said white pasty product with water so that the zirconium concentration decreases below 1 mol/liter to produce a diluted product; adjusting the pH of said diluted product to 3 to 7; and concentrating said diluted product to obtain a high dispersion product which comprises a sol or gel of isolated monoclinic zirconia microcrystals dispersed in an aqueous solution without agglomeration at a concentration of 0.1 to 1 mol/liter, wherein said monoclinic zirconia microcrystals have uniform size, and a diameter or width smaller than 100 angstroms, and wherein said sol or gel is translucent.

Claim 15

The process as defined in claim 11, wherein a high-dispersion sol is produced.

Claim 16

The process as defined in claim 11, wherein a high-dispersion gel is produced.

Claim 17

The process as defined in claim 11, wherein said aqueous solution contains 1.5 to 7 mol/liter of zirconium salt or hydroxide based on zirconium concentration and has such a composition as to produce 3 to 9 mol/liter of hydrochloric acid after hydrolysis.

Claim 18

The process as defined in claim 14, wherein said zirconium salt comprises a member selected from the group consisting of zirconyl chloride, zirconium carbonate, zirconium nitrate, zirconium sulfate, zirconium acetate, and mixtures of two or more thereof.

Claim 19

The process as defined in claim 11, wherein said hydrothermal treatment is conducted at 180° to 270° C. for 1 to 10 days.

Claim 20

The process as defined in claim 11, wherein said white pasty product is diluted so that the zirconium concentration decreases to 0.1 to 0.5 mol/liter.

Claim 21

The process as defined in claim 11, wherein said obtained high-dispersion product is a sol and wherein said sol is concentrated by heating in the range of 80° to 100° C. to produce a gel.