Ceramic coloring solution for dental use

Abstract

The present invention provides a dental ceramic coloring solution capable of inhibiting a decrease in the strength of a dental ceramic and capable of imparting a pink color tone required in dental use. The present invention relates to a coloring solution for coloring a dental ceramic, which comprises a coloring component and a solvent, the aforementioned coloring component comprising an Er component and a Co component.

Description

TECHNICAL FIELD

[0001] The present application relates to a coloring solution for dental ceramics. More specifically, it relates to a coloring solution for dental ceramics, for example, which is suitable for use in the production of dental prostheses such as inlays, onlays, veneers, crowns, bridges, abutments, dental pins, dentures, denture bases, implant components (fixtures, abutments), and the like, which are obtained by cutting using a dental CAD / CAM system. BACKGROUND

[0002] In the past, as dental products (for example, dental prostheses such as representative superstructures, crowns, caps, and dental prostheses, orthodontic products, and dental implant products), metals have often been used. However, the color of metals is significantly different from that of natural teeth, and has the disadvantage of lacking aesthetic appeal, and sometimes also causes allergies due to the elution of metals. Thus, in order to solve the problems associated with the use of metals, as a substitute material for metals, ceramic materials such as alumina (aluminum oxide) and zirconia (zirconium oxide) have been increasingly used for dental products. In particular, zirconia is excellent in strength and also has relatively good aesthetic appeal, and thus, in particular, in conjunction with the recent reduction in price, the demand is increasing.

[0003] In recent years, CAD / CAM systems that use a computer to design and a milling device to cut and process final shapes of dental prostheses or large implant prostheses are becoming widespread. As the raw material of the cutting material, i.e., the polishing blank, used in this CAD / CAM system, zirconia is often used in view of aesthetic appeal, and in particular, in recent years, zirconia that arranges different color tones vertically in the thickness direction to meet the aesthetic requirements of natural teeth is becoming increasingly popular. With respect to color tones that are difficult to reproduce, high aesthetic requirements are met by further coloring the surface of the ceramic processed into the shape of the dental prosthesis with a dental ceramic material.

[0004] However, the technique of coloring by covering a dental ceramic material requires specialized knowledge and excellent skills. Specifically, with respect to coloring achieved by a dental ceramic material, color development that requires the reproduction of the precise shape structure of natural teeth and high aesthetic appeal through the construction of a dental ceramic material requires a high degree of skill.

[0005] Thus, as a method of coloring a dental prosthesis, in order to avoid problems that arise from the use of a dental ceramic material, a technique is often used in which, instead of the coloring based on a dental ceramic material that requires skill, a coloring solution is applied to a dental ceramic to achieve coloring, thereby providing higher aesthetic appeal.

[0006] For example, Patent Literature 1 discloses a coloring solution for coloring a dental ceramic article, which contains a rare earth element metal or ion and contains a transition metal or ion as a coloring agent, and as one of the rare earth elements, erbium can be cited.

[0007] Prior Art Documents

[0008] Patent Literature

[0009] Patent Literature 1: Japanese Patent Application Laid-Open No. 2010-534245 SUMMARY

[0010] PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] On the other hand, sometimes dental ceramics are required to be colored in pink. As dental materials which require color development in pink, for example, a prosthesis including a gingival portion or the like can be cited. As the prosthesis including a gingival portion, use at a gingival margin lower portion of an upper structure body at an implant, and a large dental prosthesis which reproduces a gingival portion called ALL ON 4 (a surgery in which four implants are evenly embedded in a bone) using a prosthesis, or the like can be cited. When the coloring solution of Patent Literature 1 is used as a coloring solution for zirconia for such a use, in order to develop a pink color required in the use, a large amount of erbium including about 15 mass% or the like is required, but erbium also functions as a stabilizer for zirconia, and thus there is a problem that a physical property such as strength possessed by zirconia is reduced due to the coloring solution containing a large amount of erbium. Therefore, in a dental use in which color development in pink is required, it is not possible to make dental ceramics satisfy both color development in pink and strength.

[0012] Thus, an object of the present application is to provide a dental ceramic coloring solution which can suppress reduction in strength of a dental ceramic and can impart a pink color tone required in a dental use.

[0013] MEANS FOR SOLVING THE PROBLEM

[0014] The present inventors and others have repeatedly conducted intensive research in order to solve the above problem, and as a result, it has been found that by containing a Co component in addition to an Er component, a coloring solution which can exhibit a pink color tone required in a dental use even if the content of the Er component is reduced can be obtained, and further research has been conducted, and thus the present application has been completed.

[0015] That is, the present application includes the following technical solution.

[0016] [1] A coloring solution for coloring a dental ceramic, which contains a coloring component and a solvent,

[0017] The aforementioned coloring component contains an Er component and a Co component.

[0018] [2] The coloring solution according to [1], wherein, in (L*, a*, b*) based on the L*a*b* colorimetric system of the dental ceramic after coloring and sintering,

[0019] a* is 4.5 to 15.0,

[0020] b* is -5.0 to 10.

[0021] [3] The coloring solution according to [1] or [2], wherein, in the aforementioned (L*, a*, b*) based on the L*a*b* colorimetric system, L* is 65 to 95.

[0022] [4] The coloring solution according to any one of [1] to [3], wherein the aforementioned coloring component further comprises an Al component.

[0023] [5] The coloring solution according to any one of [1] to [4], wherein the aforementioned Er component is an ion or a complex.

[0024] [6] The coloring solution according to any one of [1] to [5], wherein the aforementioned Er component is a component from at least one selected from the group consisting of erbium chloride hydrate, erbium perchlorate hydrate, erbium nitrate hydrate, erbium oxalate hydrate, and erbium acetate hydrate.

[0025] [7] The coloring solution according to any one of [1] to [6], wherein the aforementioned Co component is an ion or a complex.

[0026] [8] The coloring solution according to any one of [1] to [6], wherein the aforementioned Co component is a component from at least one selected from the group consisting of cobalt (II) chloride hydrate, cobalt (II) perchlorate hydrate, cobalt (II) fluoride hydrate, cobalt (II) nitrate hydrate, cobalt (II) oxalate hydrate, and cobalt (II) acetate hydrate.

[0027] [9] The coloring solution according to any one of [1] to [8], wherein the content of the aforementioned Er component is 110 to 310 mmol / L in terms of Er ions.

[0028]

[10] The coloring solution according to any one of [1] to [9], wherein the content of the aforementioned Co component is 0.0340 to 1.70 mmol / L in terms of Co ions.

[0029]

[11] The coloring solution according to any one of [1] to

[10] , wherein the aforementioned solvent comprises water or / and an organic solvent.

[0030]

[12] The coloring solution according to

[11] , wherein the aforementioned organic solvent comprises at least one selected from the group consisting of alcohols, diols, triols, and ketones.

[0031]

[13] The coloring solution according to any one of [1] to

[12] , wherein the dental ceramic contains zirconia as a main component.

[0032]

[14] The coloring solution according to

[13] , wherein the dental ceramic further contains yttria.

[0033]

[15] The coloring solution according to

[14] , wherein the content ratio of yttria is 1.5 to 10 mol% with respect to the total moles of zirconia and yttria.

[0034]

[16] A dental ceramic having an Er component and a Co component supported on a surface thereof.

[0035]

[17] The dental ceramic according to

[16] , further having an Al component supported on the surface thereof.

[0036]

[18] The dental ceramic according to

[16] or

[17] , wherein the Er component is an ion or a complex.

[0037]

[19] The dental ceramic according to any one of

[16] to

[18] , wherein the Co component is an ion or a complex.

[0038]

[20] The dental ceramic according to any one of

[16] to

[19] , wherein the dental ceramic contains zirconia as a main component.

[0039]

[21] The dental ceramic according to

[20] , wherein the dental ceramic further contains yttria.

[0040]

[22] The dental ceramic according to

[21] , wherein the content ratio of yttria is 1.5 to 10 mol% with respect to the total moles of zirconia and yttria.

[0041] Effects of the Invention

[0042] According to the present application, it is possible to provide a dental ceramic coloring solution which can inhibit a decrease in strength of a dental ceramic and impart a pink color tone required in dental use. DETAILED DESCRIPTION

[0043] The present application is a coloring solution for coloring a dental ceramic, which contains a coloring component and a solvent, the coloring component containing an Er component and a Co component.

[0044] <Er component>

[0045] First, the Er component contained in the coloring component of the present application is described. The Er component contains an ion or a complex of Er, and is contained in order to color zirconia in pink.

[0046] The ion or complex of Er can be added to the coloring solution in the form of a salt containing an Er cation and anion or a complex containing Er and a ligand. As the anion or ligand, for example, OAcmay be cited - , NO3 - , NO2 - , CO3 2- , HCO3 - , ONC - , SCN - , SO4 2- , SO3 2- , glutarate, lactate, gluconate, propionate, butyrate, glucuronate, benzoate, phenate, halogen anion (fluoride, chloride, bromide), acetate, and the like. Ac means acetyl group.

[0047] As examples of specific compounds added in order to contain the above ion or complex in the coloring solution of the present application, tris(acetylacetonyl)erbium hydrate, erbium chloride hydrate (erbium chloride hexahydrate), erbium perchlorate hydrate, erbium acetate hydrate (erbium acetate tetrahydrate), erbium oxide, erbium oxalate hydrate, erbium nitrate hydrate, erbium stearate, erbium fluoride, erbium tetraborate, erbium iodide hydrate, erbium sulfide, erbium sulfate hydrate, and the like, 3-valent erbium compounds, and the like can be cited. Among these, from the viewpoints of solubility and color development, erbium chloride hydrate, erbium perchlorate hydrate, erbium nitrate hydrate, erbium oxalate hydrate, and erbium acetate hydrate are preferable. The Er component can be used alone as one kind or in combination of two or more kinds as appropriate.

[0048] As the content of the Er component in the coloring solution, 110 to 310 mmol / L, more preferably 120 to 300 mmol / L, further preferably 130 to 290 mmol / L, in terms of Er ion in the entire solution is preferable. In the case where the content is less than 110 mmol / L, color development of pink color is insufficient, and it can be impossible to satisfy high aesthetic requirements, and if the content exceeds 310 mmol / L, it can be that the Er component functions as a stabilizer for zirconia, and the strength and the like of zirconia decrease. The content of the Er component can be measured by, for example, inductively coupled plasma (ICP) emission spectrometry, fluorescence X-ray analysis, and the like. Note that the content of the metal component in the present specification can be measured by the present method.

[0049] <Co component>

[0050] Next, the Co component contained in the coloring solution of the present application is described. The Co component contains an ion or complex of Co, which does not decrease the strength and the like of zirconia, and is contained in order to color it pink.

[0051] The reason why a desired pink hue can be imparted to dental ceramics without reducing their strength by applying a coloring solution containing Co is not yet clear, but the inventors speculate as follows: It can be speculated that, in the case of zirconia, by adding a coloring solution containing Co... 4+ Compared to Co, which has a smaller valence, ions 2+ Ions, thereby introducing oxygen ion holes into the zirconium oxide crystal structure, O 2- The actual ionic radius of an ion decreases, which increases its O. 2- Ions and Zr 4+ The ratio of ionic radii stabilizes the fluorite structure, thus suppressing the reduction in the strength of zirconium oxide.

[0052] Co ions or complexes can be added to the coloring solution in the form of salts containing Co cations and anions, or complexes containing Co and its ligands. Examples of such anions or ligands include OAc. - NO3 - NO2 - CO3 2- HCO3 - ONC - SCN - SO4 2- SO3 2- Glutamate, lactate, gluconate, propionate, butyrate, glucuronide, benzoate, phenolate, halogen anions (fluorides, chlorides, bromides), acetate, etc.

[0053] As examples of specific compounds added in order to cause the coloring solution of the present application to contain the above-mentioned ions or complexes, there can be mentioned bis(acetylacetonato) cobalt (II) dihydrate, tris(acetylacetonato) cobalt (III), cobalt (II) amidosulfate hydrate, cobalt (II) benzoate, cis-dichlorotetrakisamine cobalt (III) chloride, monochloropentakisamine cobalt (III) chloride, hexakisamine cobalt (III) chloride, hexakisamine cobalt (III) nitrate, tetrakisnitrodiammine cobalt (III) ammonium sulfate, trisnitrotriamine cobalt (III), dichlorotetranitroamine cobalt (III) chloride, potassium tetrakisnitrodiammine cobalt (III) sulfate, cobalt (II) chloride hydrate (e.g., cobalt (II) chloride hexahydrate), cobalt (II) chloride, cobalt (III) chloride, cobalt (II) octoate, cobalt (II) oleate, cobalt (II) perchlorate hydrate (cobalt (II) perchlorate hexahydrate), cobalt (II) fluoride hydrate (cobalt (II) fluoride dihydrate, cobalt (II) fluoride trihydrate, cobalt (II) fluoride tetrahydrate), dicobalt octacarbonyl (Co2(CO)8), cobalt (II) formate hydrate, cobalt (II) citrate hydrate, cobalt disilicide, cobalt (II) acetate, cobalt (II) acetate hydrate (cobalt (II) acetate tetrahydrate), cobalt (II) oxide, cobalt (III) oxide, tricobalt tetraoxide (Co3(CO)4), potassium hexacyanocobalt (III) sulfate, cobalt (II) bromide, cobalt (II) bromide hydrate, cobalt (II) oxalate hydrate (e.g., cobalt (II) oxalate dihydrate, cobalt (II) oxalate tetrahydrate, etc.), cobalt resinate, cobalt (II) nitrate hydrate (cobalt (II) nitrate trihydrate, cobalt (II) nitrate hexahydrate), cobalt (II) metazirconate, cobalt (II) hydroxide, cobalt (III) hydroxide, cobalt (II) stearate, cobalt (II) selenate, cobalt (II) selenate hexahydrate, cobalt (II) tungstate tetrahydrate, cobalt (II) bicarbonate, tetrakis(thiocyanato) cobalt (II) ammonium sulfate hydrate, cobalt (II) thiocyanate, cobalt (II) metatitanate, potassium hexanitrocobalt (III) sulfate, sodium hexanitrocobalt (III) sulfate, cobalt (III) hexammine sulfate, cobalt boride, cobalt (II) molybdate hydrate, cobalt (II) iodide hydrate, cobalt (II) laurate, cobalt (II) sulfide, cobalt (II) sulfate hydrate, cobalt (II) phosphide, cobalt (II) phosphate hydrate, and the like. Of these, from the viewpoints of solubility and color development, cobalt (II) chloride hydrate, cobalt (II) perchlorate hydrate, cobalt (II) fluoride hydrate, cobalt (II) nitrate hydrate, cobalt (II) oxalate hydrate, and cobalt (II) acetate hydrate are preferred. These Co components can be used singly as one kind, or two or more kinds in appropriate combination.

[0054] The content of the Co component in the coloring solution is preferably 0.0340 to 1.70 mmol / L, more preferably 0.0380 to 1.50 mmol / L, and further preferably 0.0420 to 1.30 mmol / L in terms of Co ions in the entire solution. In the case where the content is less than 0.0340 mmol / L, it is necessary to contain more than 310 mmol / L of the Er component in order to color pink, and thus the strength and the like of the zirconia can decrease. If more than 1.70 mmol / L is compounded, the degree of blue can increase, and pink coloration can not be achieved.

[0055] The coloring solution of the present application preferably further contains an Al component. The Al component contains ions or complexes of Al, and can increase the degree of red. In addition, the strength of the zirconia can sometimes be improved.

[0056] The reason why the degree of red can be increased and the strength of the zirconia can be improved by applying the dental ceramic coloring solution containing the Al component is not certain, but the present inventors and the like speculate as follows. That is, it is presumed that, with respect to the increase in the degree of red, the presence of the diamond crystal structure of Al and the Co component causes the appearance of reddish purple, and the degree of red of the entire solution increases. In addition, it is presumed that, with respect to the improvement in the strength of the zirconia, the dispersion of the Al component between the zirconia crystals causes the increase in the bonding area between the crystals, and the bonding force between the crystals improves, and this bonding force exhibits the high toughness characteristic possessed by the Al component.

[0057] The ions or complexes of Al can be added to the coloring solution in the form of a salt containing Al cations and anions, or a complex containing Al and a ligand. As the anions or ligands, for example, OAc - , NO3 - , NO2 - , CO3 2- , HCO3 - , ONC - , SCN - , SO4 2- , SO3 2- , glutarate, lactate, gluconate, propionate, butyrate, glucuronate, benzoate, phenate, halogen anions (fluoride, chloride, bromide), acetate, and the like can be listed.

[0058] As examples of specific compounds added in order to cause the coloring solution of the present application to contain the above-described ions or complexes, mention can be made of aluminum ethoxide, aluminum butoxide, aluminum propoxide, barium aluminate, magnesium aluminate, lithium aluminate, aluminum benzoate, aluminum chloride hydrate (aluminum chloride hexahydrate), aluminum oleate, aluminum perchlorate hydrate (aluminum perchlorate trihydrate, aluminum perchlorate hexahydrate, etc.), aluminum citrate hydrate (aluminum citrate monohydrate), aluminum gluconate, lithium tetrachloroaluminate, lithium aluminum chloride, aluminum oxide, aluminum selenate hydrate, aluminum oxalate hydrate, aluminum tartrate hydrate, aluminum metazirconate, aluminum hydroxooctanoate, aluminum stearate, aluminum titanate, aluminum lactate, aluminum palmitate, lithium tetrahydroaluminate, lithium aluminum tetrahydride, aluminum iodide, aluminum laurate, aluminum butyrate, aluminum nitrate hydrate (aluminum nitrate nonahydrate, etc.), aluminum sulfide, cesium aluminum sulfate hydrate, and the like. Among these, from the viewpoint of solubility, aluminum chloride hydrate, aluminum perchlorate hydrate, aluminum oxalate hydrate, and aluminum nitrate hydrate are preferred. These Al components can be used singly or in combination of two or more as appropriate.

[0059] As the content of the Al component in the coloring solution, 0.100 to 40.0 mmol / L of the entire solution, more preferably 0.200 to 30.0 mmol / L, further preferably 0.400 to 25.0 mmol / L is preferred. In the case where the compounding amount is less than 0.100 mmol / L, it can be impossible to obtain sufficient redness, and it can be impossible to obtain the effect of improving the strength of zirconia, and if the compounding amount exceeds 40.0 mmol / L, the aesthetic property can be reduced.

[0060] The coloring solution of the present application can contain other metal components as long as the effects of the present application are not impaired. For example, if the coloring solution contains a Zr component, the strength of zirconia obtained by applying the foregoing coloring solution sometimes improves.

[0061] As the Zr component, an ion or complex containing Zr is included. The ion or complex of Zr can be added to the coloring solution in the form of a salt containing a Zr cation and an anion or a complex containing Zr and a ligand, and as the anion or ligand, mention can be made of, for example, OAc - , NO3 - , NO2 - , CO3 2- , HCO3 - , ONC - , SCN - , SO4 2- , SO3 2- , glutarate, lactate, gluconate, propionate, butyrate, glucuronate, benzoate, phenate, halogen anion (fluoride, chloride, bromide), acetate, and the like.

[0062] As examples of specific compounds added in order to cause the coloring solution of the present application to contain the above-mentioned ions or complexes, zirconium oxychloride hydrate (IV), zirconium sulfide (IV), tetrakis(acetylacetonato)zirconium (IV), zirconium chloride (IV), zirconium octoate (IV), zirconium oxyoctoate (IV), dichlorobis(η5-cyclopentadienyl)zirconium (IV), zirconium oxyacetate (IV), zirconium oxide (IV) hydrate, zirconium oxide stearate (IV), zirconium oxynitrate (IV) hydrate, zirconium n-butoxide (IV), zirconium carbide (IV), zirconium carbonate (IV) hydrate (ZrOCO3-ZrO2-nH2O), ammonium zirconium hexafluoride, zirconium iodide (IV), zirconium oxy laurate (IV) (Zr(C 11 H 23 COO)2O), zirconium sulfate (IV) hydrate, zirconium phosphate (IV) hydrate, and the like can be given. Among these, from the viewpoint of further improving the strength of the dental ceramic, zirconium oxychloride hydrate (IV), zirconium chloride (IV), zirconium oxyacetate (IV), zirconium oxide (IV) hydrate, zirconium oxynitrate (IV) hydrate are preferable, and zirconium oxychloride hydrate (IV) is more preferable. The Zr component can be used alone as one kind or in combination of two or more kinds as appropriate.

[0063] The content of the Zr component in the coloring solution is preferably 0.0650 to 0.900 mol / L, more preferably 0.0800 to 0.850 mol / L, and further preferably 0.0900 to 0.800 mol / L, from the viewpoint of improving the strength of the dental ceramic. In the case where the content is 0.0650 mol / L or more, the effect of improving the strength of the dental ceramic can be obtained, and in the case where the content is 0.900 mol / L or less, the aesthetic property of the dental ceramic is not reduced, and the strength can be improved.

[0064] The coloring solution of the present application preferably contains water and / or an organic solvent as a solvent. The water and / or the organic solvent dissolve the coloring component and the Zr component, and improve the penetration of the coloring solution into the dental ceramic. The content of the solvent in the coloring solution is preferably 45 to 99 mass%, more preferably 60 to 98.5 mass%, and further preferably 75 to 98 mass%.

[0065] The water needs to be water substantially free from impurities that adversely affect the effects of the present application, and is preferably purified water, distilled water, ion-exchanged water, or pure water. The content of the water in the coloring solution is preferably 45 to 99 mass%, more preferably 60 to 98.5 mass%, and further preferably 75 to 98 mass%.

[0066] As the organic solvent, any solvent capable of dissolving the aforementioned cations can be used, and alcohols, diols, triols, ketones, and mixtures selected from combinations thereof are preferred. As specific examples, the following can be listed: methanol, ethanol, 1-propanol, 2-propanol, isopropanol, 1-butanol, 2-butanol, 1-heptanol, 2-heptanol, 3-heptanol, 1-hexanol, 2-hexanol, 3-hexanol, 2-methyl-l-pentanol, 3-methyl-l-pentanol, 4-methyl-l-pentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 2,2-dimethyl-l-butanol, 2-ethyl-l-butanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobenzyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobenzyl ether, propylene glycol monopropyl ether, tripropylene glycol monomethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, benzyl alcohol, 2-(benzyloxy)ethanol, 3-(benzyloxy)-l-propanol, 2-(benzyloxy)-l-butanol, 5-(benzyloxy)-l-pentanol, and the like alcohols; 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,2-pentanediol, 1,5-pentanediol, 2,4-pentanediol, 1,2-hexanediol, 2,5-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol (molecular weight: 200 to 600), propylene glycol, dipropylene glycol, polypropylene glycol, 1-methyl-l,3-propanediol, 2-methyl-l,3-propanediol, 2-methyl-l,4-butanediol, 3-methyl-l,3-butanediol, 2-methyl-2,4-pentanediol, 3-methyl-l,5-pentanediol, 2,4-diethyl-l,5-pentanediol, 2-ethyl-l,3-hexanediol, and the like diols; glycerol, 1,2,4-butanetriol, 1,2,3-butanetriol, 1,2,6-hexanetriol, and the like triols; acetone, 2-butanone, 2-pentanone, isobutyronitrile, diisobutyronitrile, cyclohexanone, and the like ketones. These organic solvents can be used singly or in combination of two or more as appropriate. In addition, the organic solvent can adjust the viscosity as a thickening agent described later.

[0067] The content of the organic solvent in the colored solution is preferably 45 to 99% by mass, more preferably 60 to 98.5% by mass, and further preferably 75 to 98% by mass.

[0068] The colored solution can contain a complexing agent within a range not impairing the effects of the present application. The addition of a complexing agent improves the storage stability of the colored solution, promotes the dissolution process of the salt added to the colored solution, and / or increases the amount of the salt that can be dissolved in the colored solution, and thus is sometimes beneficial.

[0069] The complexing agent can generally form a complex with the metal ions present in the coloring solution. The complex formed must be soluble in the solvent. For example, the complexing agent can be used at least in a stoichiometric ratio with respect to the molar amount of the ions contained in the coloring solution, and good results can be obtained if the molar ratio of the complexing agent to the cations of the coloring solution is about 1 or about 2 or about 3 or more.

[0070] As examples of the complexing agent, N,N-bis(2-hydroxyethyl)glycine, acetylacetone, crown ether, cryptand, ethylenediaminetriacetate and salts thereof, ethylenediaminetetraacetate and salts thereof, nitrilotriacetate and salts thereof, citric acid and salts thereof, triethylenetetramine, porphyrin, polyacrylate, polyaspartate, acidic peptide, phthalocyanine, salicylate, glycinate, lactate, propylenediamine, ascorbate, oxalate and salts thereof, and mixtures thereof can be listed. The complexing agent can be used alone or in combination of two or more as appropriate.

[0071] The content of the complexing agent in the coloring solution is not particularly limited as long as the effects of the present application are exerted, and for example, it is preferable to contain a sufficient amount for dissolving the cations in the solution or for preventing precipitation of the cations. Specifically, in the coloring solution, it is preferable to be 0.01% by mass or more, more preferably 0.05% by mass or more, and further preferably 0.10% by mass or more. In addition, there is no particular upper limit to the content, and it is preferable to be 50% by mass or less, more preferably 20% by mass or less, and further preferably 10% by mass or less. If the amount of the complexing agent used is too small, there is a possibility that it is not completely dissolved, and if the amount of the complexing agent used is too large, there is a possibility that the excess complexing agent itself does not dissolve but remains.

[0072] The pH of the coloring solution of the present application is preferably 0 to 9, more preferably 1 to 7, and further preferably 2 to 6. In the case where the pH is outside the above range, there are cases where the cations start to precipitate from the solution. For example, in the case where the coloring solution is an aqueous solution, it is preferable to be a pH of 0 to 9. In addition, in the case where the coloring solution does not contain a complexing agent, it is preferable to be a pH of 0 to 6, and in the case where a complexing agent is contained, it is preferable to be a pH of 3 to 9. The pH can be measured using a pH meter (for example, a small pH meter LAQUA twin manufactured by HORIBA, Ltd., or the like) which is a commercially available product.

[0073] The coloring solution of the present application preferably has a suitable viscosity in a manner that not only enables application of a necessary amount of the solution to the surface of the ceramic, but also enables movement in the fine pores of the ceramic green body (also referred to as "shaped body" in the present specification) or the ceramic pre-fired body. As the suitable viscosity, it is preferably 0.1 to 10,000 mPa, more preferably 0.5 to 6,000 mPa, and further preferably 1 to 3,000 mPa at, for example, 20°C. In the case where the viscosity is too high, it can not be contained in the fine pores of the ceramic green body and the ceramic pre-fired body. The method of measuring the viscosity is not particularly limited, and it can be measured at 25°C using a Brookfield viscometer.

[0074] In the coloring solution of the present application, a thickening agent can be contained within a range that does not impair the effects of the present application, for the purpose of making a suitable viscosity.

[0075] As the thickening agent, the viscosity can be adjusted by selecting from the aforementioned organic solvents, or it can be selected from the following thickening agents. As thickening agents other than the aforementioned organic solvents, polysaccharide compounds such as methylcellulose, carboxycellulose, hydroxyethylcellulose, xanthan gum, guar gum, carrageenan, tamarind gum, pectin, sugar alcohol compounds such as sorbitol, erythritol, xylitol, trehalose, synthetic polyol compounds such as diglycerin, triglycerin, polyglycerin, polyvinyl alcohol, solid organic compounds such as sodium polyacrylate, ammonium polyacrylate, polyethylene oxide, polyethylene glycol (molecular weight of 1,000 or more), polyvinylpyrrolidone, calcium stearate, magnesium stearate, zinc stearate, aluminum stearate, polyethylene glycol monostearate, 12-hydroxystearic acid, stearamide, oleamide, ethylene bisoleamide, and the like. The thickening agent can be used alone or in combination of two or more.

[0076] The content of the thickening agent in the coloring solution of the present application is preferably 0.01 to 10% by mass, more preferably 0.02 to 8% by mass, and further preferably 0.05 to 5% by mass.

[0077] The coloring solution of the present application can contain other additives as long as the effects of the present application are not impaired.

[0078] As the additives, stabilizers (for example, methoxyphenol, hydroquinone, Topanol A (2,4-dimethyl-6-tert-butylphenol), and mixtures thereof (excluding stabilizers capable of inhibiting the phase change of zirconia)), buffers (for example, acetate, amino buffers, and mixtures thereof), preservatives (for example, sorbic acid, benzoic acid, and mixtures thereof), and mixtures thereof can be exemplified. The additives can be used alone or in combination of two or more.

[0079] The content of the additive in the colored solution of the present application can be set to, for example, 0.01 to 10 mass%, 0.05 to 5 mass%, or 0.1 to 3 mass%.

[0080] The colored solution of the present application can contain a colorant that discolors after firing of the zirconia. As the colorant that discolors after firing of the zirconia, there is no limitation as long as it discolors after firing of the zirconia and satisfies the aforementioned color difference before and after firing, and an organic pigment can be cited.

[0081] As the aforementioned organic pigment, there is no particular limitation as long as it is an organic pigment having a chromophore group and dissolving in the colored solution, and an aromatic organic pigment, i.e., an organic pigment containing one or more optionally substituted aromatic groups, is preferred, and an aromatic organic pigment having a chromophore group and a co-chromophore group is more preferred. As the chromophore group, there is no particular limitation as long as it is an atomic group that binds to an aromatic ring and becomes a color development reason, and a nitro group, an azo group, a ketimide group (>C=N-), a carbonyl group, a carbon-carbon double bond, a carbon-carbon triple bond, a carbon-nitrogen multiple bond, a thiocarbonyl group, a nitroso group, an oxoazo group, and the like can be cited. The organic pigment can contain one of these atomic groups alone or two or more of these atomic groups in appropriate combination. In addition, as the co-chromophore group, a hydroxyl group, an amino group, a carboxyl group, a sulfone group, a halogen atom, and the like can be cited. The organic pigment can contain one of these co-chromophore groups alone or two or more of these co-chromophore groups in appropriate combination.

[0082] Further, as the colorant which is decolorized after firing of the zirconia, since a substance which is harmful or toxic to the human body cannot be used, as the organic colorant, a food colorant is preferable, and a food colorant which is dissolved in the coloring solution is more preferable. As such a food colorant, there can be listed organic colorants containing two or more aromatic groups, such as Yellow No. 4 (tartrazine), Yellow No. 5 (sunset yellow FCF), Red No. 2 (amaranth), Red No. 102 (new coccine), Blue No. 1 (brilliant blue FCF), Blue No. 2 (eriochrome cinnoline), Green No. 3 (fast green FCF), Red No. 102 (new coccine), and the like; organic colorants containing a condensed aromatic group having xanthene as a parent nucleus (xanthene-based colorant), such as Acid Red 289, bromo-orthophenanthroline red, rhodamine B, rhodamine 6G, rhodamine 6GP, rhodamine 3GO, rhodamine 123, eosin (eosin B, eosin Y), fluorescein, fluorescein isothiocyanate, and the like; carmine colorant (carmine acid colorant); beet-based colorant, such as beetroot red (main components: isobetanin and betanin), betanin, isobetanin, propyl betanin, neobetanin, and the like; and the like, and preferably, organic colorants containing two or more aromatic groups and having a ketone imide group or an azo group as a color-developing group, such as Yellow No. 4 (tartrazine), Yellow No. 5 (sunset yellow FCF), Red No. 2 (amaranth), Red No. 102 (new coccine), Blue No. 1 (brilliant blue FCF), Green No. 3 (fast green FCF), isobetanin, and the like. Further, the colorant (A) can also be changed depending on the content of the stabilizer of the zirconia pre-fired body to which the coloring solution of the present application is applied, and therefore, in a certain suitable embodiment, the colorant (A) can be listed as a coloring solution for zirconia, that is, an organic colorant containing two or more aromatic groups and having a ketone imide group or an azo group as a color-developing group, and containing a sulfone group as an auxiliary color-developing group. In the present specification, the "aromatic group" includes an aromatic group in which the ring structure is composed of only carbon atoms, and a heteroaromatic group in which the ring structure contains an element other than carbon (oxygen, nitrogen, and the like). The colorant which is decolorized after firing of the zirconia can be used alone or in combination of two or more as appropriate. Further, the color-developing strength of the colorant which is decolorized after firing of the zirconia varies depending on the pH of the coloring solution, and sometimes, the structure of the compound varies depending on the pH, but as long as the effect of the present application is exerted, the pH of the coloring solution for zirconia is not particularly limited, and a pH which shows an appropriate color-developing strength can be adopted and used depending on the kind of the colorant which is decolorized after firing of the zirconia.

[0083] As the content of the colorant which is decolorized after firing of the zirconia, as long as the liquid component can develop color, there is no particular limitation, and preferably, 0.009 to 3.0% by mass, more preferably 0.09 to 1.6% by mass, further preferably 0.2 to 1.4% by mass, and particularly preferably 0.25 to 1.2% by mass, relative to the mass of the entire coloring solution.

[0084] As one embodiment, a coloring solution in which a coloring component does not substantially contain a coloring agent that is decolorized after firing of zirconia can be cited. By the coloring agent that is decolorized after firing of zirconia, it is meant that the content of the coloring agent that is decolorized after firing of zirconia is preferably less than 0.009% by mass, more preferably less than 0.001% by mass, further preferably less than 0.0001% by mass, and can be 0% by mass, with respect to the mass of the entire coloring solution.

[0085] In the coloring solution of the present application, a pink color tone required in dental use can be imparted to the dental ceramic. In the colorimetric values (L*, a*, b*) based on the L*a*b* color system of the dental ceramic after coloring and sintering, as a*, it is preferably 4.5 to 15.0, more preferably 4.8 to 14.5, further preferably 5.0 to 14.0. As b*, it is preferably -5.0 to 10, more preferably -4.4 to 9, further preferably -4.0 to 8. As L*, it is preferably 65 to 95, more preferably 68 to 92, further preferably 70 to 90. The measurement method of the aforementioned colorimetric values (L*, a*, b*) is as described in the Examples.

[0086] The dental ceramic colored with the coloring solution of the present application is not particularly limited as long as it contains a ceramic, and substances containing zirconia (also referred to as "zirconia" or "Zr02"), alumina (also referred to as "alumina" or "AI2O3"), feldspar glass, disilicate glass, ceramic material, and the like can be cited. The dental ceramic preferably contains zirconia and / or alumina, and more preferably contains zirconia as a main component. In the case where the dental ceramic contains zirconia as a main component, the content of zirconia is further preferably 65% by mass or more, particularly preferably 75% by mass or more, and most preferably 85% by mass or more.

[0087] The dental ceramic colored with the coloring solution of the present application can be a non-fired body or a pre-fired body as long as it is a ceramic before sintering, and from the viewpoint of penetration of the coloring solution, in the case where the dental ceramic contains zirconia as a main component, the dental ceramic is preferably a zirconia pre-fired body.

[0088] As other embodiments of the present application, dental ceramics (colored ceramic pre-fired bodies or unfired bodies) carrying an Er component and a Co component on their surfaces can be cited. As the contents of the Er component and the Co component, there are no particular limitations as long as the effects of the present application are exerted, and they can be appropriately adjusted by the application amount of the coloring solution of the present application and the like, according to the desired color strength after sintering and the like. In addition, as the range of carrying of the Er component and the Co component, they can be appropriately adjusted to be carried not only on the surface but also inside the surface, by being immersed into the space communicating with the outside of the ceramic pre-fired body or unfired body by capillary phenomenon, according to the application of the coloring solution of the present application and the like. Note that the carrying is usually in a state of being attached to a carrier, and in the present application, it is in a state of being attached to a ceramic by adsorption and the like.

[0089] The dental ceramic of the present application does not decrease the strength after firing, and can impart a pink color tone required in dental applications.

[0090] As described above, the ceramic pre-fired body or unfired body more preferably contains zirconia as the main component. Hereinafter, zirconia will be described. Note that in the present application, the pre-fired body before coloring with the coloring solution is simply written as "zirconia pre-fired body", and the pre-fired body after coloring is distinguished as "colored zirconia pre-fired body". Note that the coloring solution of the present application can also be used to color a zirconia unfired body, and in this case, a zirconia sintered body is produced without going through a pre-fired body. In the case of envisioning such a sintered body, as a suitable embodiment of the zirconia unfired body, the conditions in the respective descriptions below relating to the zirconia pre-fired body can be similarly applied.

[0091] The zirconia pre-fired body in the present application will be described. The zirconia pre-fired body refers to a substance obtained by forming a zirconia (Zr02: zirconia) as a main component according to a dental product as a target, and pre-firing the zirconia. The zirconia pre-fired body refers to a substance obtained by, for example, agglomerating zirconia particles (powder) in a state of not being completely sintered. The main component can be 50% by mass or more. The content of zirconia in the zirconia pre-fired body of the present application is preferably 60% by mass or more, more preferably 70% by mass or more, and further preferably 80% by mass or more. For example, if it is used in applications such as dental prostheses and dental implant products, the zirconia pre-fired body can be produced by pressure molding a zirconia powder using a known technique, and performing a pre-firing process and the like on the obtained disc or block. The density of the zirconia pre-fired body is preferably 2.7 g / cm 3 The density of the zirconia pre-fired body is preferably 4.0 g / cm 3 The density of the zirconia pre-fired body is more preferably 3.8 g / cm 3 The density of the zirconia pre-fired body is further preferably 3.6 g / cm3 The density of the zirconia preform is preferably 5.5 g / cm3 or more, more preferably 6.0 g / cm3 or more, and further preferably 6.5 g / cm3 or more. If the density is within this range, the molding process can be easily performed. The density of the preform can be calculated, for example, as (mass of the preform) / (volume of the preform). In addition, the three-point bending strength of the zirconia preform is preferably 15 to 70 MPa, more preferably 18 to 60 MPa, and further preferably 20 to 50 MPa. With respect to the aforementioned bending strength, a test piece having a thickness of 5 mm x width of 10 mm x length of 50 mm is used, and the measurement can be performed in accordance with ISO 6872:2015, except for the size of the test piece. The faces and C faces (faces obtained by chamfering the corners of the test piece at an angle of 45°) of the test piece are surface-finished in the length direction using sandpaper of No. 600. The test piece is disposed with the widest face facing the vertical direction (direction of the load). In the bending test measurement, the span is set to 30 mm, and the crosshead speed is set to 0.5 mm / minute.

[0092] The main crystal system of the zirconia in the zirconia preform, the zirconia powder, and the molded body of the zirconia powder is preferably monoclinic. In the present application, "the main crystal system is monoclinic" means that the proportion of the monoclinic crystal system in the zirconia, calculated using the following formula (1), is 50% or more, relative to the total amount of the crystal systems (monoclinic, tetragonal, and cubic) in the zirconia. m The proportion of the monoclinic crystal system in the zirconia, calculated using the following formula (1), is 50% or more, relative to the total amount of the crystal systems (monoclinic, tetragonal, and cubic) in the zirconia preform, the zirconia powder, and the molded body of the zirconia powder. m The proportion of the monoclinic crystal system in the zirconia, calculated using the following formula (1), is 50% or more, relative to the total amount of the crystal systems (monoclinic, tetragonal, and cubic) in the zirconia preform, the zirconia powder, and the molded body of the zirconia powder. m The proportion of the monoclinic crystal system in the zirconia, calculated using the following formula (1), is 50% or more, relative to the total amount of the crystal systems (monoclinic, tetragonal, and cubic) in the zirconia preform, the zirconia powder, and the molded body of the zirconia powder.

[0093] In the zirconia preform, the peaks of the tetragonal and cubic crystal systems can not be substantially detected. That is, the proportion of the monoclinic crystal system f m may be set to 100%.

[0094] [Num 1]

[0095]

[0096] In formula (1), I m (111) and I m(11-1) represents the peak intensity of the (11-1) face of the monoclinic system of zirconia. I t (111) represents the peak intensity of the (111) face of the tetragonal system of zirconia. I c (111) represents the peak intensity of the (111) face of the cubic system of zirconia.

[0097] The zirconia calcine of the present application preferably contains a stabilizer capable of inhibiting the phase transition of zirconia. For example, the zirconia before calcination preferably contains a stabilizer capable of inhibiting the phase transition of zirconia.

[0098] As the stabilizer capable of inhibiting the phase transition of zirconia, there can be mentioned, for example, oxides such as yttria (Y2O3) (hereinafter referred to as "yttria"), calcium oxide (CaO), magnesium oxide (MgO), yttria, ceria (CeO2), scandia (Sc2O3), niobia (Nb2O5), lanthana (La2O3), erbia (Er2O3), praseodymia (Pr6O 11 ), samaria (Sm2O3), europia (Eu2O3), and thulia (Tm2O3), and yttria is preferred. They can be used singly or in combination of two or more. In a certain suitable embodiment, there can be mentioned a colored solution of dental ceramics containing zirconia as a main component, containing yttria as a stabilizer, and in which the stabilizer is substantially only yttria. In the foregoing suitable embodiment, the stabilizer being substantially only yttria means that the content of the stabilizer other than yttria is less than 0.1 mol% in 100 mol% of the total of zirconia and the stabilizer, preferably 0.05 mol% or less, more preferably 0.01 mol% or less, and further preferably 0.001 mol% or less. In particular, since the colored solution contains an Er component, in the foregoing suitable embodiment, a deep pink color is assumed to be the extent that the colored solution described in the present application contains an Er component and the dental ceramics also contains an Er component, and therefore, the dental ceramics preferably does not contain erbia as a stabilizer. Of these, in the foregoing embodiment, the dental ceramics which does not contain erbia as a stabilizer can contain a trace amount of erbia as a pigment.

[0099] In the case where the stabilizer is contained in the zirconia calcined body, the content of the stabilizer is preferably 0.1 to 18 mol%, more preferably 1 to 15 mol%, and further preferably 1.5 to 10 mol% in 100 mol% of the total of the zirconia and the stabilizer. In a suitable embodiment, a dental ceramic containing zirconia as a main component and a coloring solution for coloring the same can be exemplified, in which the content of yttria is 1.5 to 10 mol% relative to the total moles of the zirconia and the yttria. In the aforementioned suitable embodiment, the content of the yttria is preferably 2.0 to 9.0 mol%, more preferably 2.5 to 8.5 mol%, and further preferably 2.8 to 8.0 mol%.

[0100] The zirconia calcined body in the present application can contain, as needed, a colorant (including a pigment, a composite pigment, and a fluorescent agent), alumina (AI2O3), titania (TiO2), silica (SiO2), and the like. These components can be used alone or in combination of two or more. As the aforementioned pigment, an oxide of at least one element selected from the group of Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Y, Zr, Sn, Sb, Bi, Ce, Pr, Sm, Eu, Gd, Tb, and Er can be exemplified. As the aforementioned composite pigment, (Zr, V)O2, Fe(Fe, Cr)2O4, (Ni, Co, Fe)(Fe, Cr)2O4 · ZrSiO4, (Co, Zn)AI2O4, and the like can be exemplified. As the aforementioned fluorescent agent, Y2SiO5:Ce, Y2SiO5:Tb, (Y, Gd, Eu)BO3, Y2O3:Eu, YAG:Ce, ZnGa2O4:Zn, BaMgAl 10 O 17 :Eu, and the like can be exemplified.

[0101] A general production method of the zirconia calcined body in the present application is described. First, a granule composed of a zirconia raw material containing a stabilizer (suitably, a zirconia granule of which main crystal system is monoclinic crystal system) is prepared, and is press-formed into a block or a disc, or the like. Next, the formed body is subjected to a CIP (Cold Isostatic Pressing) treatment as needed. The pressure at this time is, for example, 50 to 500 MPa. Next, a pre-burning treatment is performed thereon. With respect to the pre-burning, by slowly raising the temperature from room temperature to 800 to 1200°C, and staying at the aforementioned temperature for about 1 to 6 hours, a zirconia calcined body can be obtained. The obtained zirconia calcined body is subjected to a cutting process using a publicly known device according to the final dental product. For example, in the case where the dental product is a dental prosthesis, a cutting process into a crown shape is performed using CAD / CAM, or the like.

[0102] The zirconia calcine can use a commercially available product. As the commercially available product, "NORITAKE Zirconia (registered trademark)" (model: disc UTML, disc STML, disc ML, disc HT, disc LT) (manufactured by Kureha Noritake Dental Co., Ltd.), and the like can be listed.

[0103] The manufacturing method of the colored zirconia calcine of the present application includes a step of making the zirconia calcine after the cutting process contain the aforementioned coloring solution. As the method of containing the aforementioned coloring solution, a method of applying the zirconia calcine with a pen or the like, or immersing the zirconia calcine in a container filled with the coloring solution, or spraying the zirconia calcine with a sprayer, or the like can be listed, and a publicly known device can be used. Note that, in the case of manufacturing the zirconia sinter directly from the uncalcined body without including the calcining step, the zirconia uncalcined body after the cutting process can be made to contain the aforementioned coloring solution.

[0104] The present application also includes a zirconia sinter formed from the aforementioned colored zirconia calcine. The manufacturing method of the zirconia sinter includes a step of calcining the aforementioned colored zirconia calcine. The calcining temperature (the maximum temperature of the calcining) can be appropriately changed depending on the kind of the zirconia, and is not particularly limited as long as the coloring of the Er component and the Co component contained in the coloring solution occurs, and is preferably 1350°C or higher, more preferably 1450°C or higher, and further preferably 1500°C or higher. The upper limit of the calcining temperature is not particularly limited, and is preferably 1700°C or lower, for example. Note that the zirconia sinter includes not only a sinter obtained by sintering the formed zirconia particles under normal pressure and / or non-pressurized conditions, but also a sinter that is densified by a high-temperature pressurizing treatment such as HIP (Hot Isostatic Pressing) treatment.

[0105] The content of the stabilizer in the zirconia sinter can be measured by, for example, inductively coupled plasma (ICP) emission spectrometry, fluorescent X-ray analysis, or the like.

[0106] The zirconia sinter in the present application preferably has at least one of partially stabilized zirconia and fully stabilized zirconia as a matrix phase. In the zirconia sinter, the main crystal phase of the zirconia is at least one of tetragonal system and cubic system. The zirconia sinter can contain both of the tetragonal system and the cubic system. The zirconia sinter preferably substantially does not contain a monoclinic system. Note that the zirconia that is partially stabilized by the addition of the stabilizer is called partially stabilized zirconia (PSZ), and the zirconia that is fully stabilized is called fully stabilized zirconia.

[0107] The present application includes a dental product formed of the aforementioned zirconia sintered body. As the dental product, a dental prosthesis, an orthodontic product, or a dental implant product, etc. can be exemplified. As the dental prosthesis, an inlay, an onlay, a laminate veneer, a crown, etc. made of zirconia can be used, for example.

[0108] In any of the above-described embodiments, the kind, content, etc. of each component can be appropriately changed, and with respect to optional components, addition, deletion, etc. can be made. In any of the above-described embodiments, the values of the composition and properties of the coloring solution can be appropriately changed and combined.

[0109] The present application includes embodiments obtained by various combinations of the above-described configurations within the technical scope of the present application as long as the effects of the present application are exerted.

[0110] Embodiments

[0111] The present application will be described in more detail by Examples below, but the present application is not limited to the following Examples.

[0112] [Examples 1 to 17 and Comparative Examples 1 to 3]

[0113] The coloring solutions of each of the Examples and Comparative Examples were prepared as follows, and the properties thereof were evaluated. The results are shown in Tables 1 and 2.

[0114] [Preparation of Coloring Solution]

[0115] The coloring solutions were prepared by mixing each of the components described in Tables 1 and 2 at the amounts described in the tables at ordinary temperature. The molar concentration of each of the metal components in the coloring solution was measured by an inductively coupled plasma (ICP) emission spectrometer (SPS3500: Hitachi High-Tech Science Co., Ltd.).

[0116] [Preparation of Zirconia Calcined Body]

[0117] Next, the preparation of the zirconia calcined body to which the aforementioned coloring solution is to be applied will be described.

[0118] First, a zirconia powder containing a stabilizer was produced. To a zirconia powder 90.1 mass% of which was of a monoclinic crystal system, yttria 9.9 mass% (5.5 mol%) as a stabilizer was added to produce a mixture. Next, the mixture was added to water to produce a slurry, and the mixture was wet-pulverized using a ball mill to an average particle diameter of 0.13 μm or less. The pulverized slurry was dried using a spray drier, and the resulting powder was fired at 950°C for 2 hours to produce a powder (primary powder). Note that the aforementioned average particle diameter can be found by a laser diffraction scattering method. Specifically, the laser diffraction scattering method can be measured by, for example, a laser diffraction particle size distribution measuring device (SALD-2300: manufactured by Shimadzu Corporation), using a 0.2% sodium hexametaphosphate aqueous solution as a dispersion medium, and measuring on a volume basis.

[0119] To the pulverized slurry, a binder was added, and then dried using a spray drier to produce a powder (secondary powder). The produced secondary powder was used as a raw material powder for producing a zirconia calcined body described later.

[0120] Next, a method for producing a zirconia calcined body will be described. The aforementioned raw material powder 1.32 g was filled into a mold having a diameter of 19 mm, and one-press molding was performed at a surface pressure of 57.5 kN for 20 seconds using a single-screw press molding machine. The resulting one-press molded body was fired at 1000°C for 2 hours to produce a zirconia calcined body.

[0121] [Measurement of chromaticity of sintered body and evaluation of color]

[0122] The aforementioned prepared coloring solution was applied to the aforementioned produced zirconia calcined body, and firing was performed using the firing conditions described in Tables 1 and 2 to obtain a sintered body. The obtained sintered body was ground and processed into a round plate having a diameter of 15 mm and a thickness of 1.2 mm, and a spectrophotometer (trade name: "Crystal Ace 100-DC / JP", light source: 7 band LED light source) manufactured by Olympus Corporation was used to measure the chromaticity based on L * a * b * Colorimetric system (JIS Z 8781-4: 2013 Colorimetry - Part 4: CIE 1976 L * a * b * a color space) under a white background (n = 3). The average of the measured values is shown in Tables 1 and 2. In addition, the color of the obtained sintered body was evaluated by visual observation.

[0123] [Measurement of biaxial flexural strength of sintered body]

[0124] After the aforementioned colored solution was applied to the aforementioned zirconia calcined body, the calcination conditions described in Tables 1 and 2 were used to perform calcination, thereby obtaining sintered bodies having a diameter of 15 mm and a thickness of 1.2 mm. The biaxial flexural strength of the obtained sintered bodies was measured (n = 5) using a table universal precision testing machine Autograph (trade name "AGS-X") manufactured by Shimadzu Corporation in accordance with JIS T 6526:2012 at a crosshead speed of 0.5 mm / minute. The average of the measured values is shown in Tables 1 and 2.

[0125] In addition, the change rate of the biaxial flexural strength was calculated using the following formula, taking the zirconia sintered body that was not colored using the colored solution (Comparative Example 1) as a reference.

[0126] Biaxial flexural strength change rate (%) = {(biaxial flexural strength of the sintered body obtained by applying the colored solution and performing calcination - biaxial flexural strength of the zirconia sintered body that was not colored) / biaxial flexural strength of the zirconia sintered body that was not colored} x 100

[0127] [Table 1]

[0128]

[0129] [Table 2]

[0130]

[0131] As shown in Table 2, in addition, Comparative Example 1, which was not applied with the colored solution, was white and did not color to pink. In Comparative Example 2, which was colored using a colored solution containing only an Er component, the biaxial flexural strength was reduced by 35.9% compared to Comparative Example 1, which was not applied with the colored solution. In Comparative Example 3, which was colored using a colored solution containing only a Co component, the coloration was blue-purple and pink coloration was not possible. In contrast, as shown in Tables 1 and 2, in Examples 1 to 17, the strength reduction of the zirconia was suppressed and pink coloration was possible.

[0132] Industrial applicability

[0133] The colored solution of the present application can inhibit the decrease in the strength of dental ceramics and can impart a pink color tone required in dental use, and thus, can be suitably used as a dental ceramic coloring solution. In particular, as the demand for ceramic dental crowns is increasing and the personal aesthetic requirements are increasing, the use frequency of the dental ceramic coloring solution is expected to increase, and thus, the dental ceramic coloring solution of the present application is useful. The colored solution of the present application can be suitably used for a prosthesis including a gingival portion. As the prosthesis including a gingival portion, there can be cited the use at the lower portion of the gingival margin at the superstructure of an implant, and a large dental prosthesis reproducing a gingival portion using a prosthesis, which is called ALL ON 4 (a surgery of embedding 4 implants in a balanced manner into a bone), and the like.

Claims

1. A coloring solution for coloring a dental ceramic, comprising a coloring ingredient and a solvent, the coloring ingredient comprising an Er ingredient and a Co ingredient, the content of the Er ingredient being 110 to 310 mmol / L in terms of Er ions, and the content of the Co ingredient being 0.0340 to 1.70 mmol / L in terms of Co ions.

2. The tinting solution of claim 1, wherein, in the L*a*b* color system, (L*, a*, b*) of the dental ceramic after coloring and sintering, a* is 4.5 to 15.0, b* is -5.0 to 10.

3. The tinting solution of claim 2, wherein, in the L*a*b* color system, L* is 65 to 95.

4. The tinting solution of claim 1 or 2, wherein, the coloring ingredient further comprises an Al ingredient.

5. The tinting solution of claim 1 or 2, wherein, the Er ingredient is an ion or a complex.

6. The tinting solution of claim 1 or 2, wherein, the Er ingredient is at least one ingredient selected from the group consisting of erbium chloride hydrate, erbium perchlorate hydrate, erbium nitrate hydrate, erbium oxalate hydrate, and erbium acetate hydrate.

7. The tinting solution of claim 1 or 2, wherein, the Co ingredient is an ion or a complex.

8. The tinting solution of claim 1 or 2, wherein, the Co ingredient is at least one ingredient selected from the group consisting of cobalt (II) chloride hydrate, cobalt (II) perchlorate hydrate, cobalt (II) fluoride hydrate, cobalt (II) nitrate hydrate, cobalt (II) oxalate hydrate, and cobalt (II) acetate hydrate.

9. The tinting solution of claim 1 or 2, wherein, the solvent comprises water or / and an organic solvent.

10. The tinting solution of claim 9, wherein, the organic solvent comprises at least one selected from the group consisting of alcohols and ketones.

11. The tinting solution of claim 9, wherein, the organic solvent comprises at least one selected from the group consisting of diols and triols.

12. The tinting solution of claim 1 or 2, wherein, the dental ceramic contains zirconia as a main ingredient.

13. The tinting solution of claim 12, wherein, the dental ceramic further contains yttria.

14. The tinting solution of claim 13, wherein, the content of yttria is 1.5 to 10 mol% relative to the total moles of zirconia and yttria.

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