Dental porcelain material preventing yellow coloration and method for producing same
AssigneeNoritake Co., Limited
InventorsTadao Kamiya, Motoyuki Inoue, Hiroshi Inada
Life of this patent
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Abstract
A dental porcelain material free of yellow coloring or opacification upon firing is produced. A powder mixture is prepared by adding 0.1 to 2.0 wt % of antimony trioxide and 0.01 to 5 wt % of nitric acid or its salt or salt, to a porcelain starting material. The powder mixture is heat-treated at a temperature not lower than the softening temperature of the powder mixture to produce a fused mass which is pulverized and water-washed. 0.01 to 5 wt % of nitric acid or its salt or salts may be added again during the pulverizing step.
Claims29
A method for producing a dental porcelain material comprising:
- providing a powder mixture by adding to a porcelain starting frit material 0.1 to 2.0 wt % of powders of antimony trioxide and 0.01 to 5 wt % of at least one nitric acid component selected from the group consisting of nitric acid and salts thereof, based on the total weight of the porcelain starting frit material,
- heat-treating said powder mixture at a temperature not lower than the softening temperature of said powder mixture to produce a fused mass, and
- pulverizing and water-washing said fused mass in which 0.01 to 5 wt %, based on the total weight of the powder mixture, of at least one further nitric acid component selected from the group consisting of nitric acid and salts thereof is further added to said fused mass during said pulverizing step, said dental porcelain material having resistance to yellow coloration after repeated firings exceeding at least five times.
A method for producing a dental porcelain material comprising:
- providing a powder mixture by adding to a porcelain starting frit material 0.1 to 2.0 wt % of powders of antimony trioxide and 0.01 to 5 wt % of at least one nitric acid component selected from the group consisting of nitric acid and salts thereof, based on the total weight of the porcelain starting frit material,
- heat-treating said powder mixture at a temperature not lower than the softening temperature of said powder mixture to produce a fused mass, and
- pulverizing and water-washing said fused mass in which 0.01 to 5 wt %, based on the total weight of the powder mixture, of at least one further nitric acid component selected from the group consisting of nitric acid and salts thereof is further added to said fused mass during said pulverizing step.
A dental porcelain material consisting essentially of a porcelain starting frit material and 0.1 to 2.0 wt % of antimony trioxide and 0.01 to 5 wt % of at least one nitric acid component selected from the group consisting of nitric acid and salts thereof, based on the total weight of a porcelain starting frit material, said dental porcelain material having resistance to yellow coloration after at least ten firings.
Dependencies are inferred from the claim text.