JP6949606B2 - Manufacturing method of zirconia molded product - Google Patents

Description

The present invention relates to a method for producing a zirconia molded product for forming a dental material and the like.

In recent years, zirconia sintered bodies have come to be clinically used as dental materials for artificial teeth and the like. However, the translucency of a general zirconia sintered body is not so high. Therefore, from the viewpoint of obtaining artificial teeth having excellent aesthetics, development of a zirconia sintered body having high translucency is desired. As a method for obtaining a zirconia sintered body having high translucency, for example, a method of reducing the crystal grain size of the zirconia sintered body by using zirconia particles having a small particle size can be considered. For example, Patent Document 1 describes a specific translucent zirconia sintered body in which the primary particles have dimensions of 100 nm or less.

By the way, in many cases, an artificial tooth made of a zirconia sintered body is formed by press-molding zirconia particles or molding using a slurry or composition containing zirconia particles (for example, cast molding, injection molding, etc.). A zirconia molded body having a desired shape such as a disk shape or a prismatic shape is obtained, and then this is calcined to obtain a calcined body (mill blank), which is used as a target artificial tooth by using CAD data or the like. It is manufactured by cutting (milling) into the shape of the above and then sintering it. In such a method, since the shavings after cutting (milling) are discarded, only a small part of the mill blank can be used as an artificial tooth, and the zirconia raw material is wasted. In addition, many mill blanks are monolithic for reasons such as ease of manufacturing, but the artificial teeth obtained from such mill blanks have to have a monotonous color tone, and the color tone of each patient's teeth must be changed. It is difficult to produce a corresponding artificial tooth.

As a solution to the above problems, a stereolithography (SLA) method for obtaining artificial teeth by a laminated molding (3D printing) technique without going through cutting (milling) of a mill blank has been studied. For example, in Patent Document 2, a thin layer of a paste-like composition containing a ceramic powder and a photocurable resin is adhered on a support, and this layer is locally cured by the action of radiation and is placed on the treated layer. A method for producing a ceramic piece that can be used for a dental structure or the like by repeating the operation of welding a new layer into small pieces, removing organic components from the small pieces by thermal decomposition, and further sintering the pieces is described. ing.

Special Table 2010-514665 Special Table 2005-516878A

It is desired to form a dense zirconia sintered body in order to obtain an artificial tooth having high translucency and excellent aesthetics by a stereolithography method. As a means for obtaining a dense zirconia sintered body, it is conceivable to increase the content of the zirconia particles in the composition containing the zirconia particles and the polymerizable monomer used as much as possible. However, increasing the content of zirconia particles tends to increase the viscosity of the composition, and the layer is cured by stereolithography, especially by irradiating light from the underside of the optically transparent container through the bottom surface of the container. When carrying out the regulated liquid level method for forming the target product, it becomes difficult to obtain a zirconia molded product having a desired shape. This problem becomes particularly remarkable when zirconia particles having a small particle size are used.

Therefore, the present invention is for forming a dental material, which can easily obtain a zirconia molded body having a desired shape for forming a dental material such as an artificial tooth by a stereolithography method using zirconia particles having a small particle size. A method for producing a zirconia molded product, which is a method for producing a zirconia molded product which can provide a dense zirconia sintered body and can be used as a dental material having high translucency and excellent aesthetics. The purpose is to provide. Further, the present invention relates to a zirconia molded product obtained by the production method, a method for producing a zirconia calcined product using the zirconia molded product, a zirconia calcined product obtained thereby, and a method for producing a zirconia sintered body and the like. It is an object of the present invention to provide a zirconia sintered body obtained by the above.

As a result of diligent studies to achieve the above object, the present inventors have found that the proportion of zirconia particles monodispersed in the composition containing the zirconia particles and the polymerizable monomer used for stereolithography ( When the degree of monodispersity is set to a specific range, a zirconia molded product having a desired shape and capable of providing a dense zirconia sintered body and having high translucency and excellent aesthetics can be obtained. We have found that can be easily obtained, and based on this finding, further studies have been carried out to complete the present invention.

That is, the present invention relates to the following [1] to [20].
[1] A method for producing a zirconia molded product for forming a dental material, which comprises a step of photoforming using a composition containing zirconia particles and a polymerizable monomer, and the average primary particle diameter of the zirconia particles is 30 nm. The production method according to the following, wherein the zirconia particles have a monodispersity of 50% or more.
[2] The production method according to [1], wherein the zirconia particles contain 3 to 9 mol% of yttria.
[3] The production method according to [1], wherein the zirconia particles contain 4.5 to 7 mol% of yttria.
[4] The production method according to any one of [1] to [3], wherein the polymerizable monomer is a radically polymerizable monomer.
[5] The production method according to any one of [1] to [4], wherein the composition contains a photopolymerization initiator.
[6] The production method according to any one of [1] to [5], wherein the composition contains 20 to 90% by mass of zirconia particles.
[7] The production method according to any one of [1] to [6], wherein the composition has a viscosity at 25 ° C. of 20,000 mPa · s or less.
[8] The composition is produced by a method having a step of mixing a slurry containing zirconia particles and a polymerizable monomer, and the slurry is a slurry of a dispersion medium other than water [1]. The production method according to any one of [7].
[9] The production method according to any one of [1] to [8], which is stereolithographically formed by a regulated liquid level method.
[10] A zirconia molded product for forming a dental material obtained by the production method according to any one of [1] to [9].
[11] A method for producing a zirconia calcined product for forming a dental material, which comprises a step of calcining the zirconia molded product for forming a dental material obtained by the production method according to any one of [1] to [9].
[12] The production method according to [11], which is calcined at 200 ° C. or higher and lower than 900 ° C.
[13] A zirconia calcined product for forming a dental material obtained by the production method according to [11] or [12].
[14] Production of a zirconia sintered body for a dental material, which comprises a step of sintering a zirconia molded product for forming a dental material obtained by the production method according to any one of [1] to [9] under normal pressure. Method.
[15] The production method according to [14], wherein sintering is performed at 900 ° C. or higher and 1200 ° C. or lower.
[16] A method for producing a zirconia sintered body for dental materials, which comprises a step of sintering a zirconia calcined product for forming a dental material obtained by the production method according to [11] or [12] under normal pressure.
[17] The production method according to [16], wherein sintering is performed at 900 ° C. or higher and 1200 ° C. or lower.
[18] The production method according to any one of [14] to [17], wherein the zirconia sintered body has a light transmittance of 30% or more at a wavelength of 700 nm at a thickness of 0.5 mm.
[19] The production method according to any one of [14] to [18], wherein the zirconia sintered body is an artificial tooth.
[20] A zirconia sintered body for dental materials obtained by the production method according to any one of [14] to [19].

According to the present invention, for forming a dental material, it is possible to easily obtain a zirconia molded body having a desired shape for forming a dental material such as an artificial tooth by a stereolithography method using zirconia particles having a small particle size. This is a method for producing a zirconia molded product, which is capable of producing a zirconia molded product which can provide a dense zirconia sintered body and can be used as a dental material having high translucency and excellent aesthetics. The method is provided. Further, according to the present invention, a zirconia molded product obtained by the production method, a method for producing a zirconia calcined product using the zirconia molded product, a zirconia calcined product obtained thereby, and a method for producing a zirconia sintered body. And the resulting zirconia sintered body is provided.

Hereinafter, embodiments of the present invention will be described. The following description does not limit the present invention.

[Manufacturing method of zirconia molded product]
The method of the present invention for producing a zirconia molded product for forming a dental material includes a step of photoforming using a composition containing zirconia particles and a polymerizable monomer, and the average primary particle size of the zirconia particles is large. It is 30 nm or less, and the monodispersity of the zirconia particles is 50% or more.

-Zirconia particles The average primary particle size of the zirconia particles used is 30 nm or less because a zirconia sintered body having high translucency can be produced and the effect of the present invention is more prominently exhibited. It is preferably 20 nm or less, more preferably 15 nm or less, may be 10 nm or less, preferably 1 nm or more, and more preferably 5 nm or more. The average primary particle size of the zirconia particles is, for example, that the zirconia particles (primary particles) are photographed with a transmission electron microscope (TEM), and the particle size of each particle is obtained for 100 arbitrary particles on the obtained image. (Maximum diameter) can be measured and calculated as the average value thereof.

Further, the zirconia particles used preferably have a content of primary particles of 50 nm or more of 5% by mass or less, preferably 3% by mass or less, because a zirconia sintered body having excellent translucency can be obtained. It is more preferable that the amount is 1% by mass or less. The content can be measured by, for example, a zeta potential measuring device.

In the present invention, the monodispersity of zirconia particles (ratio of the number of zirconia particles monodispersed as primary particles without agglomeration) needs to be 50% or more in the above composition to be subjected to photomolding. Is. As a result, it is possible to easily obtain a zirconia molded product having a desired shape and capable of providing a dense zirconia sintered body, which can be used as a dental material having high translucency and excellent aesthetics. From such a viewpoint, the monodispersity is preferably 60% or more, and more preferably 70% or more.

In the above composition to be subjected to stereolithography, when the monodispersity of the zirconia particles is within the above range, a dense zirconia sintered body can be provided, and a dental material having high translucency and excellent aesthetics. The reason why the zirconia molded product can be obtained is not always clear, but it can be considered as follows.
That is, in general, in a zirconia molded product obtained by stereolithography, zirconia particles are dispersed in a photopolymerized polymer, and the polymer is incinerated and disappears in the process of calcining or sintering the zirconia molded product. Therefore, it is considered that the zirconia particles dispersed in the polymer approach each other and finally come into contact with each other to form a densely aggregated state. In the above-mentioned photomolding, when a composition having a high degree of monodispersity of zirconia particles is used as in the present invention, a zirconia molded body having a high degree of monodisperse of zirconia particles can be obtained, and such a zirconia molded body is calcined. Or sintering, a more uniform agglomerated state of zirconia particles can be achieved, and more uniform crystal growth proceeds in the remaining sintering process, resulting in a dense and highly translucent zirconia sintered body. As a result, it is considered that dental materials such as artificial teeth having excellent aesthetics can be obtained. On the other hand, in the above-mentioned photomolding, when a composition having a low degree of monodispersion of zirconia particles is used, a zirconia molded product having a low degree of monodisperse of zirconia particles, in other words, more zirconia particles are already aggregated in the photopolymerized polymer. When the zirconia molded product is calcined or sintered, a non-uniform agglomerated state is generated, which hinders the uniform growth of crystals, and as a result, the resulting zirconia sintered body It is considered that the density and translucency are reduced.

The monodispersity of the zirconia particles in the composition to be subjected to photoforming is, for example, a slice having a thickness of 200 nm is cut out from a cured product obtained by polymerizing and curing the composition, and the slice is subjected to a transmission electron microscope (TEM). It can be obtained from the obtained image by taking a picture. The magnification of the transmission electron microscope (TEM) depends on the content of the zirconia particles, the primary particle size, and the like, but is usually 50,000 times or more, preferably 100,000 times or more. For all zirconia particles existing in the specified region in the photographed visual field, the number of primary particles of all zirconia particles is set to X, and among these, the particles do not come into contact with each other and aggregate as primary particles. The number of zirconia particles that are monodispersed is Y, and the degree of monodispersity can be calculated by the following formula.
Monodispersity (%) = 100 x Y / X
It is desirable to define the region in the field of view taken so that the number of X's is 200 or more. More specifically, the monodispersity can be determined by the method described in Examples described later.

The yttria content in the zirconia particles used can be the same as the yttria content in the target zirconia sintered body. Since a zirconia sintered body having excellent translucency and strength can be obtained, the content of itria in the zirconia particles can be, for example, 2 mol% or more, preferably 3 mol% or more, and 4 It is more preferably mol% or more, more preferably 4.5 mol% or more, 5 mol% or more, further 5.5 mol% or more, and 9 mol% or less. It is preferably 8 mol% or less, more preferably 7 mol% or less. The yttria content in the zirconia particles means the ratio (mol%) of the number of moles of yttria to the total number of moles of zirconia and yttria.

The method for preparing zirconia particles is not particularly limited, and for example, a breakdown process in which coarse particles are crushed into fine particles, a building-up process in which atoms or ions are synthesized by a nucleation / growth process, or the like can be adopted. Of these, the building-up process is preferable in order to obtain fine zirconia particles of high purity.

The breakdown process can be performed, for example, by pulverizing with a ball mill, a bead mill, or the like. At this time, it is preferable to use a pulverized medium having a small size, and for example, it is preferable to use a pulverized medium having a size of 100 μm or less. Further, it is preferable to classify after crushing.

On the other hand, as a building-up process, for example, a vapor phase thermal decomposition method in which an oxidate of a metal ion having a high vapor pressure or an organic metal compound is thermally decomposed while being vaporized to precipitate an oxide; Gas phase reaction method in which synthesis is performed by vapor phase chemical reaction between gas and reaction gas; evaporation concentration method in which raw materials are heated and vaporized and rapidly cooled in an inert gas at a predetermined pressure to condense vapor into fine particles; A melt method in which the liquid is cooled and solidified as small droplets to form a powder; a solvent evaporation method in which the solvent is evaporated to increase the concentration in the liquid and precipitate in a hypersaturated state; the solute concentration is hypersaturated by reaction with a precipitant or hydrolysis. Then, a precipitation method in which a sparingly soluble compound such as an oxide or a hydroxide is precipitated through a nucleation-growth process can be mentioned.

The precipitation method is a uniform precipitation method in which a precipitant is generated in a solution by a chemical reaction to eliminate local non-uniformity of the precipitant concentration; a plurality of metal ions coexisting in the liquid are simultaneously precipitated by the addition of the precipitant. Precipitation method; Hydrolysis method for obtaining oxides or hydroxides by hydrolysis from alcohol solutions such as metal salt solutions and metal alkoxides; Solvent thermal synthesis methods for obtaining oxides or hydroxides from high-temperature and high-pressure fluids. The sorbothermal synthesis method is further subdivided into a hydrothermal synthesis method using water as a solvent, a supercritical synthesis method using a supercritical fluid such as water or carbon dioxide as a solvent, and the like.

For any building-up process, it is preferable to increase the precipitation rate in order to obtain finer zirconia particles. Further, it is preferable to classify the obtained zirconia particles.

As the zirconium source in the building-up process, for example, nitrate, acetate, chloride, alkoxide and the like can be used, and specifically, zirconium oxychloride, zirconium acetate, zirconium nitrate and the like can be used.

Further, yttria can be blended in the process of producing the zirconia particles so that the content of yttria contained in the zirconia particles is within the above range. For example, yttria may be solid-dissolved in the zirconia particles. As the yttrium source, for example, nitrate, acetate, chloride, alkoxide and the like can be used, and specifically, yttrium chloride, yttrium acetate, yttrium nitrate and the like can be used.

If necessary, the zirconia particles are organic compounds having an acidic group; fatty acid amides such as saturated fatty acid amides, unsaturated fatty acid amides, saturated fatty acid bisamides, and unsaturated fatty acid bisamides; silane coupling agents (organic silicon compounds), organic titanium. The surface may be treated in advance with a known surface treatment agent such as a compound, an organic zirconium compound, or an organic metal compound such as an organic aluminum compound. By surface-treating the zirconia particles, it is possible to suppress an excessive increase in the viscosity of the composition used for photoforming, and the compatibility between the zirconia particles and the dispersion medium in the slurry containing the zirconia particles as described later and the zirconia. In some cases, the compatibility between the particles and the polymerizable monomer can be adjusted, and the degree of monodispersity of the zirconia particles can be improved. Among the above surface treatment agents, the increase in viscosity can be suppressed more effectively, the compatibility with the dispersion medium and the polymerizable monomer is excellent, and the chemistry between the zirconia particles and the polymerizable monomer is excellent. An organic compound having an acidic group is preferable because the strength of the zirconia molded product obtained by increasing the bondability can be improved.

Examples of the organic compound having an acidic group include an organic compound having at least one acidic group such as a phosphoric acid group, a carboxylic acid group, a pyrophosphate group, a thiophosphate group, a phosphonic acid group and a sulfonic acid group. Among them, a phosphoric acid group-containing organic compound having at least one phosphoric acid group and a carboxylic acid group-containing organic compound having at least one carboxylic acid group are preferable, and a phosphoric acid group-containing organic compound is more preferable. The zirconia particles may be surface-treated with one kind of surface treatment agent, or may be surface-treated with two or more kinds of surface treatment agents. When the zirconia particles are surface-treated with two or more kinds of surface treatment agents, the surface treatment layer by the zirconia particles may be a surface treatment layer of a mixture of two or more kinds of surface treatment agents, or a plurality of surface treatment layers. It may be a surface-treated layer having a laminated multi-layer structure.

Examples of the phosphoric acid group-containing organic compound include 2-ethylhexyl acid phosphate, stearyl acid phosphate, 2- (meth) acryloyloxyethyl dihydrogen phosphate, 3- (meth) acryloyloxypropyl dihydrogen phosphate, 4- ( Meta) Acryloyloxybutyl dihydrogen phosphate, 5- (meth) acryloyloxypentyl dihydrogen phosphate, 6- (meth) acryloyloxyhexyl dihydrogen phosphate, 7- (meth) acryloyloxyheptyl dihydrogen phosphate, 8 -(Meta) acryloyloxyoctyldihydrogen phosphate, 9- (meth) acryloyloxynonyldihydrogen phosphate, 10- (meth) acryloyloxydecyldihydrogen phosphate, 11- (meth) acryloyloxyundecyldihydrogen Phosphate, 12- (meth) acryloyl oxide decyldihydrogen phosphate, 16- (meth) acryloyloxyhexadecyldihydrogen phosphate, 20- (meth) acryloyloxyicosyldihydrogen phosphate, bis [2- (meth) Acryloyloxyethyl] hydrogen phosphate, bis [4- (meth) acryloyloxybutyl] hydrogen phosphate, bis [6- (meth) acryloyloxyhexyl] hydrogen phosphate, bis [8- (meth) acryloyloxyoctyl] hydro Genphosphate, bis [9- (meth) acryloyloxynonyl] hydrogen phosphate, bis [10- (meth) acryloyloxydecyl] hydrogen phosphate, 1,3-di (meth) acryloyloxypropyl dihydrogenphosphate, 2 -(Meta) acryloyloxyethyl phenylhydrogen phosphate, 2- (meth) acryloyloxyethyl-2-bromoethyl hydrogen phosphate, bis [2- (meth) acryloyloxy- (1-hydroxymethyl) ethyl] hydrogen phosphate , And these acid groups, alkali metal salts, ammonium salts and the like.

Examples of the carboxylic acid group-containing organic compound include succinic acid, oxalic acid, octanoic acid, decanoic acid, stearic acid, polyacrylic acid, 4-methyloctanoic acid, neodecanoic acid, pivalic acid, 2,2-dimethylbutyric acid, and 3 , 3-Dimethylbutyric acid, 2,2-dimethylvaleric acid, 2,2-diethylbutyric acid, 3,3-diethylbutyric acid, naphthenic acid, cyclohexanedicarboxylic acid, (meth) acrylic acid, N- (meth) acryloylglycine, N -(Meta) acryloyl aspartic acid, O- (meth) acryloyl tyrosine, N- (meth) acryloyl tyrosine, N- (meth) acryloyl-p-aminobenzoic acid, N- (meth) acryloyl-o-aminobenzoic acid, p-vinyl benzoic acid, 2- (meth) acryloyloxy benzoic acid, 3- (meth) acryloyloxy benzoic acid, 4- (meth) acryloyloxy benzoic acid, N- (meth) acryloyl-5-aminosalicylic acid, N- (Meta) acryloyl-4-aminosalicylic acid, 2- (meth) acryloyloxyethyl hydrogen succinate, 2- (meth) acryloyloxyethyl hydrogenphthalate, 2- (meth) acryloyloxyethyl hydrogenmalate, 2- (2- (2-methoxyethoxy) ethoxy) acetic acid (commonly known as "MEEAA"), 2- (2-methoxyethoxy) acetic acid (commonly known as "MEAA"), mono [2- (2-methoxyethoxy) ethyl] ester of succinate , Maleic acid mono [2- (2-methoxyethoxy) ethyl] ester, glutarate mono [2- (2-methoxyethoxy) ethyl] ester, malonic acid, glutaric acid, 6- (meth) acryloyloxyhexane-1, 1-dicarboxylic acid, 9- (meth) acryloyloxynonane-1,1-dicarboxylic acid, 10- (meth) acryloyloxydecane-1,1-dicarboxylic acid, 11- (meth) acryloyloxyundecane-1,1- Dicarboxylic acid, 12- (meth) acryloyl oxidedecane-1,1-dicarboxylic acid, 13- (meth) acryloyloxytridecane-1,1-dicarboxylic acid, 4- (meth) acryloyloxyethyl trimerite, 4- (Meta) acryloyloxybutyl trimerite, 4- (meth) acryloyloxyhexyl trimerite, 4- (meth) acryloyloxydecyl trimerite, 2- (meth) acryloyloxyethyl-3'-(meth) acryloyl Oxy-2'-(3, 4-Dicarboxybenzoyloxy) propyl succinate and acid anhydrides, acid halides, alkali metal salts, ammonium salts and the like thereof can be mentioned.

Examples of the organic compound having at least one acidic group other than the above, such as a pyrophosphate group, a thiophosphate group, a phosphonic acid group, and a sulfonic acid group, include those described in International Publication No. 2012/042911. Can be used.

Examples of the saturated fatty acid amide include palmitate amide, stearic acid amide, and behenic acid amide. Examples of the unsaturated fatty acid amide include oleic acid amide and erucic acid amide. Examples of the saturated fatty acid bisamide include ethylene bispalmitic acid amide, ethylene bisstearic acid amide, and hexamethylene bisstearic acid amide. Examples of the unsaturated fatty acid bisamide include ethylene bisoleic acid amide, hexamethylene bisoleic acid amide, and N, N'-diorail sebacic acid amide.

Examples of the silane coupling agent (organic silicon compound) include ^{a compound represented by R 1} _n SiX _4-n (in the formula, R ¹ is a substituted or unsubstituted hydrogen atom having 1 to 12 carbon atoms. It is a group, X is an alkoxy group having 1 to 4 carbon atoms, a hydroxy group, a halogen atom or a hydrogen atom, and n is an integer of 0 to 3, except when there are a plurality of ^{R 1 and X, respectively.} , It may be the same or different).

Specific examples of the silane coupling agent (organic silicon compound) include methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, and phenyltriethoxysilane. Diphenyldiethoxysilane, isobutyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, 3,3,3-trifluoropropyltrimethoxysilane, methyl-3,3,3- Trifluoropropyldimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxy Silane, γ-methacryloyloxypropylmethyldimethoxysilane, γ-methacryloyloxypropylmethyldiethoxysilane, N- (β-aminoethyl) γ-aminopropylmethyldimethoxysilane, N- (β-aminoethyl) γ-aminopropyltri Methoxysilane, N- (β-aminoethyl) γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercapto Propyltrimethoxysilane, trimethylsilanol, methyltrichlorosilane, methyldichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, vinyltrichlorosilane, trimethylbromosilane, diethylsilane, vinyltriacetoxysilane, ω-( Meta) acryloyloxyalkyltrimethoxysilane [(meth) carbon number between acryloyloxy group and silicon atom: 3-12, eg γ-methacryloyloxypropyltrimethoxysilane], ω- (meth) acryloyloxyalkyl Examples thereof include triethoxysilane [the number of carbon atoms between the (meth) acryloyloxy group and the silicon atom: 3 to 12, eg, γ-methacryloyloxypropyltriethoxysilane, etc.]. In addition, in this specification, the notation "(meth) acryloyl" is used in the meaning which includes both methacryloyl and acryloyl.

Among these, a silane coupling agent having a functional group is preferable, and ω- (meth) acryloyloxyalkyltrimethoxysilane [the number of carbon atoms between the (meth) acryloyloxy group and the silicon atom: 3 to 12], ω- (Meta) acryloyloxyalkyltriethoxysilane [(meth) carbon number between acryloyloxy group and silicon atom: 3 to 12], vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, γ-glycid Xipropyltrimethoxysilane is more preferred.

Examples of the organic titanium compound include tetramethyl titanate, tetraisopropyl titanate, tetra n-butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate and the like.

Examples of the organic zirconium compound include zirconium isopropoxide, zirconium n-butoxide, zirconium acetylacetonate, and zirconyl acetate.

Examples of the organoaluminum compound include aluminum acetylacetonate and aluminum organolate chelate compounds.

The specific method of surface treatment is not particularly limited, and a known method can be adopted. For example, a method of spray-adding the above-mentioned surface treatment agent while vigorously stirring the zirconia particles, or a method of adding the zirconia particles to an appropriate solvent. A method of removing the solvent after dispersing or dissolving the above-mentioned surface treatment agent and the above-mentioned surface treatment agent can be adopted. The solvent may be an organic solvent as described later. Further, a method of adding the above-mentioned surface treatment agent to a composition containing zirconia particles and a polymerizable monomer, stirring and dispersing may be adopted. Further, after dispersing or dissolving the zirconia particles and the above-mentioned surface treatment agent, reflux or high-temperature and high-pressure treatment (autoclave treatment or the like) may be performed.

It is desirable that the content of the zirconia particles in the composition to be subjected to stereolithography be as large as possible from the viewpoint of later sinterability and the effect of the present invention being more prominent. Specifically, it is preferably 20% by mass or more, more preferably 30% by mass or more, further preferably 40% by mass or more, and particularly preferably 50% by mass or more. On the other hand, in the stereolithography method, it is desirable that the viscosity of the composition is within a certain range from the principle of the laminated molding. Therefore, the content of the zirconia particles in the composition is 90% by mass or less. It is preferably 80% by mass or less, more preferably 70% by mass or less, and particularly preferably 60% by mass or less. The viscosity of the composition is adjusted when a regulated liquid level method is carried out in which the layers are cured by irradiating light from the lower side of the container through the bottom surface of the container to sequentially form zirconia molded articles one by one. It may be particularly important to raise the cured layer by one layer and allow the composition for forming the next layer to flow smoothly between the bottom surface of the cured layer and the bottom surface of the vessel. ..

The specific viscosity of the composition is preferably 20,000 mPa · s or less, more preferably 10,000 mPa · s or less, and 5,000 mPa · s or less as the viscosity at 25 ° C. It is more preferable that the viscosity is 100 mPa · s or more. In the composition, the higher the content of the zirconia particles, the higher the viscosity tends to be. Therefore, the balance between the speed at the time of stereolithography and the accuracy of the obtained zirconia molded product is adjusted according to the performance of the stereolithography apparatus used. It is preferable to appropriately adjust the balance between the content of the zirconia particles and the viscosity in the above composition while also taking into consideration the above. The viscosity can be measured using an E-type viscometer.

-Polymeric monomer The type of polymerizable monomer used is not particularly limited, and is a monofunctional polymerizable monomer such as monofunctional (meth) acrylate and monofunctional (meth) acrylamide. , And any of polyfunctional polymerizable monomers such as bifunctional aromatic compounds, bifunctional aliphatic compounds, and trifunctional or higher functional compounds. One type of polymerizable monomer may be used alone, or two or more types may be used. As the polymerizable monomer, a radically polymerizable monomer is preferable, and a (meth) acrylic monomer is more preferable. In addition, in this specification, the notation "(meth) acrylic" is used in the meaning which includes both methacrylic and acrylic. Further, from the viewpoint of efficiently carrying out the stereolithography method, the polymerizable monomer is preferably a polyfunctional polymerizable monomer.

Examples of the monofunctional (meth) acrylate include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6. (Meta) acrylate having a hydroxyl group such as −hydroxyhexyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, propylene glycol mono (meth) acrylate, glycerol mono (meth) acrylate, erythritol mono (meth) acrylate; methyl ( Meta) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) Alkyl (meth) acrylates such as acrylates, n-hexyl (meth) acrylates, lauryl (meth) acrylates, cetyl (meth) acrylates and stearyl (meth) acrylates; oil rings such as cyclohexyl (meth) acrylates and isobornyl (meth) acrylates. Formula (meth) acrylate; aromatic group-containing (meth) acrylate such as benzyl (meth) acrylate and phenyl (meth) acrylate; 2,3-dibromopropyl (meth) acrylate, 3- (meth) acryloyloxypropyltrimethoxysilane , 11- (Meta) Acryloyloxyundecyltrimethoxysilane and other (meth) acrylates having a functional group can be mentioned.

Examples of the monofunctional (meth) acrylamide include (meth) acrylamide, N- (meth) acryloylmorpholin, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-. Di-n-propyl (meth) acrylamide, N, N-di-n-butyl (meth) acrylamide, N, N-di-n-hexyl (meth) acrylamide, N, N-di-n-octyl (meth) Examples thereof include acrylamide, N, N-di-2-ethylhexyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N, N- (dihydroxyethyl) (meth) acrylamide and the like.

Among these monofunctional polymerizable monomers, (meth) acrylamide is preferable in terms of excellent polymerizable properties, and N- (meth) acryloylmorpholine, N, N-dimethyl (meth) acrylamide, N, N- Diethyl (meth) acrylamide is more preferred.

Examples of the bifunctional aromatic compound include 2,2-bis ((meth) acryloyloxyphenyl) propane and 2,2-bis [4- (3-acryloyloxy-2-hydroxypropoxy) phenyl] propane. 2,2-Bis [4- (3-methacryloyloxy-2-hydroxypropoxy) phenyl] propane (commonly known as "Bis-GMA"), 2,2-bis (4- (meth) acryloyloxyethoxyphenyl) propane, 2 , 2-bis (4- (meth) acryloyloxypolyethoxyphenyl) propane, 2,2-bis (4- (meth) acryloyloxydiethoxyphenyl) propane, 2,2-bis (4- (meth) acryloyloxy) Tetraethoxyphenyl) propane, 2,2-bis (4- (meth) acryloyloxypentaethoxyphenyl) propane, 2,2-bis (4- (meth) acryloyloxydipropoxyphenyl) propane, 2- (4-( Meta) acryloyloxydiethoxyphenyl) -2- (4- (meth) acryloyloxyethoxyphenyl) propane, 2-(4- (meth) acryloyloxydiethoxyphenyl) -2- (4- (meth) acryloyloxyditri Ethoxyphenyl) propane, 2- (4- (meth) acryloyloxydipropoxyphenyl) -2- (4- (meth) acryloyloxytriethoxyphenyl) propane, 2,2-bis (4- (meth) acryloyloxypropoxy) Phenyl) propane, 2,2-bis (4- (meth) acryloyloxyisopropoxyphenyl) propane, 1,4-bis (2- (meth) acryloyloxyethyl) pyromeritate and the like can be mentioned. Among these, 2,2-bis [4- (3-methacryloyloxy-2-hydroxypropoxy) phenyl] propane (commonly known as "Bis-GMA"), which is excellent in polymerizability and the strength of the obtained zirconia molded product, 2,2-Bis (4- (meth) acryloyloxypolyethoxyphenyl) propane is preferred. Among 2,2-bis (4- (meth) acryloyloxypolyethoxyphenyl) propane, 2,2-bis (4-methacryloyloxypolyethoxyphenyl) propane (average number of moles of ethoxy group added is 2.6). Compounds (commonly known as "D-2.6E")) are preferred.

Examples of the bifunctional aliphatic compound include glycerol di (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, and propylene glycol di (meth) acrylate. , Butylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-Hexanediol di (meth) acrylate, 2-ethyl-1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol di (meth) Examples thereof include acrylate, 1,2-bis (3-methacryloyloxy-2-hydroxypropoxy) ethane, and 2,2,4-trimethylhexamethylenebis (2-carbamoyloxyethyl) dimethacrylate (commonly known as "UDM"). Among these, triethylene glycol dimethacrylate (commonly known as "TEGDMA") and 2,2,4-trimethylhexamethylenebis (2-carbamoyloxyethyl) dimethacrylate are excellent in terms of polymerizability and strength of the obtained zirconia molded product. Is preferable.

Examples of the trifunctional or higher functional compound include trimethylolpropane tri (meth) acrylate, trimethylolethanetri (meth) acrylate, trimethylolmethane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, and pentaerythritol tetra (pentaerythritol tetra (meth) acrylate. Meta) acrylate, dipentaerythritol penta (meth) acrylate, N, N- (2,2,4-trimethylhexamethylene) bis [2- (aminocarboxy) propan-1,3-diol] tetra (meth) acrylate, Examples thereof include 1,7-diacryloyloxy-2,2,6,6-tetra (meth) acryloyloxymethyl-4-oxyheptane. Among these, N, N- (2,2,4-trimethylhexamethylene) bis [2- (aminocarboxy) propane-1,3-diol] is excellent in terms of polymerizability and strength of the obtained zirconia molded product. Tetramethacrylate, 1,7-diacryloyloxy-2,2,6,6-tetraacryloyloxymethyl-4-oxyheptane is preferred.

The content of the polymerizable monomer in the composition to be subjected to photoforming is preferably 10% by mass or more, preferably 20% by mass or more, from the viewpoint of more efficient photoforming. It is more preferably 30% by mass or more, particularly preferably 40% by mass or more, preferably 80% by mass or less, and more preferably 70% by mass or less. , 60% by mass or less, and particularly preferably 50% by mass or less.

-Photopolymerization initiator In the process of stereolithography using a composition containing zirconia particles and a polymerizable monomer, the polymerizable monomer in the composition is polymerized and the composition is locally cured. , The desired zirconia molded product is obtained. Curing of the composition is preferably carried out using a photopolymerization initiator, and the composition preferably further contains a photopolymerization initiator. The type of the photopolymerization initiator is not particularly limited and can be appropriately selected from the photopolymerization initiators used in the general industry. Among them, the photopolymerization initiator used for dental applications is preferable.

Specific photopolymerization initiators include, for example, (bis) acylphosphine oxides (including salts), thioxanthones (including salts such as quaternary ammonium salts), ketals, α-diketones, and coumarins. , Anthraquinones, benzoin alkyl ether compounds, α-aminoketone compounds and the like. As the photopolymerization initiator, one type may be used alone, or two or more types may be used in combination. Among these photopolymerization initiators, it is preferable to use at least one selected from the group consisting of (bis) acylphosphine oxides and α-diketones. As a result, it is possible to more efficiently produce a zirconia molded product having excellent photocurability in both the ultraviolet region (including the near-ultraviolet region) and the visible light region and having a desired shape by a stereolithography method. , Ar laser, He-Cd laser, etc .; Sufficient stereolithography can be performed using any light source such as halogen lamp, xenon lamp, metal halide lamp, light emitting diode (LED), mercury lamp, fluorescent lamp, etc. Can be done.

Among the (bis) acylphosphine oxides, examples of the acylphosphine oxides include 2,4,6-trimethylbenzoyldiphenylphosphine oxide (commonly known as "TPO"), 2,6-dimethoxybenzoyldiphenylphosphine oxide, and 2, 6-dichlorobenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylmethoxyphenylphosphine oxide, 2,4,6-trimethylbenzoylethoxyphenylphosphine oxide, 2,3,5,6-tetramethylbenzoyldiphenylphosphine oxide, benzoyldi -(2,6-dimethylphenyl) phosphonate, sodium salt of 2,4,6-trimethylbenzoylphenyl phosphine oxide, potassium salt of 2,4,6-trimethylbenzoyldiphenyl phosphine oxide, 2,4,6-trimethylbenzoyldiphenyl Examples include the ammonium salt of phosphine oxide.

Among the above (bis) acylphosphine oxides, examples of the bisacylphosphine oxides include bis (2,6-dichlorobenzoyl) phenylphosphine oxide and bis (2,6-dichlorobenzoyl) -2,5-dimethylphenyl. Phosphine oxide, bis (2,6-dichlorobenzoyl) -4-propylphenylphosphine oxide, bis (2,6-dichlorobenzoyl) -1-naphthylphosphine oxide, bis (2,6-dimethoxybenzoyl) phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,5-dimethylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) Examples thereof include phenylphosphine oxide and bis (2,3,6-trimethylbenzoyl) -2,4,4-trimethylpentylphosphine oxide. Further, the compounds described in JP-A-2000-159621 can also be used.

Among these (bis) acylphosphine oxides, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylmethoxyphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine Oxides, sodium salts of 2,4,6-trimethylbenzoylphenylphosphine oxides are preferred.

Examples of α-diketones include diacetyl, benzyl, camphorquinone, 2,3-pentadione, 2,3-octadione, 9,10-phenanthrenequinone, 4,4'-oxybenzyl, acenaphthenicone and the like. .. Among these, camphorquinone is preferable, especially when a light source in the visible light region is used.

The content of the photopolymerization initiator in the composition used for stereolithography depends on the type of photopolymerization initiator used and the like, but is 0.01% by mass or more from the viewpoint of the efficiency of stereolithography. It is preferably 0.02% by mass or more, more preferably 5% by mass or less, and even more preferably 3% by mass or less.

-Fluorescent agent When a composition containing a fluorescent agent (a composition containing zirconia particles, a polymerizable monomer and a fluorescent agent) is used, a fluorescent zirconia sintered body can be easily obtained. From this point of view, the composition used for stereolithography preferably contains a fluorescent agent.

The type of fluorescent agent used is not particularly limited, and one or more of those capable of emitting fluorescence with light of any wavelength can be used. Examples of such a fluorescent agent include those containing a metal element. Examples of the metal element include Ga, Bi, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Tm and the like. The fluorescent agent may contain one of these metal elements alone, or may contain two or more of these metal elements. Among these metal elements, Ga, Bi, Eu, Gd, and Tm are preferable, and Bi and Eu are more preferable, because the effect of the present invention is more remarkably exhibited. Examples of the fluorescent agent used include oxides, hydroxides, acetates and nitrates of the above metal elements. The fluorescent agents are Y ₂ SiO ₅ : Ce, Y ₂ SiO ₅ : Tb, (Y, Gd, Eu) BO ₃ , Y ₂ O ₃ : Eu, YAG: Ce, ZnGa ₂ O ₄ : Zn, BaMgAl ₁₀ O. ₁₇ : It may be Eu or the like.

The amount of the fluorescent agent used is not particularly limited and can be appropriately adjusted according to the type of the fluorescent agent and the intended use of the finally obtained zirconia sintered body, but the finally obtained zirconia sintered body is used for dentistry. From the viewpoint of use as a material, the content of the fluorescent agent in the composition is preferably 0.001% by mass or more in terms of the oxide of the metal element contained in the fluorescent agent with respect to the mass of zirconia. It is more preferably 0.005% by mass or more, further preferably 0.01% by mass or more, preferably 1% by mass or less, and more preferably 0.5% by mass or less. , 0.1% by mass or less is more preferable. When the content is not less than the above lower limit, a zirconia sintered body having no inferior fluorescence as compared with human natural teeth can be obtained, and when the content is not more than the above upper limit, the zirconia sintered body can be obtained. It is possible to suppress a decrease in translucency and strength in the zirconia sintered body.

The composition provided for stereolithography may further include a colorant and / or a translucency modifier. When the composition further contains a colorant and / or a translucency adjusting agent, a zirconia molded product containing these components, and thus a zirconia calcined product or a zirconia sintered body containing these components can be obtained.

The zirconia sintered body becomes a colored zirconia sintered body by containing a colorant. The type of colorant that can be contained in the above composition is not particularly limited, and a known pigment generally used for coloring ceramics, a known dental liquid colorant, or the like can be used. Examples of the colorant include those containing a metal element, and specific examples thereof include oxides containing metal elements such as iron, vanadium, placeodium, erbium, chromium, nickel and manganese, composite oxides and salts. .. A commercially available colorant can also be used, and for example, Prettau Color Liquid manufactured by Zirkonzan can be used. The above composition may contain one kind of colorant or may contain two or more kinds of colorants.

The amount of the colorant used is not particularly limited and can be appropriately adjusted according to the type of the colorant and the intended use of the finally obtained zirconia sintered body, but the finally obtained zirconia sintered body is used for dentistry. From the viewpoint of use as a material, the content of the colorant in the composition is preferably 0.001% by mass or more in terms of the oxide of the metal element contained in the colorant with respect to the mass of zirconia. It is more preferably 0.005% by mass or more, further preferably 0.01% by mass or more, preferably 5% by mass or less, more preferably 1% by mass or less, and 0. It is more preferably 5.5% by mass or less, and may be 0.1% by mass or less, more preferably 0.05% by mass or less.

Examples of the translucency adjusting agent that can be contained in the above composition include aluminum oxide, titanium oxide, silicon dioxide, zircon, lithium silicate, lithium disilicate and the like. The composition may contain one kind of translucency adjusting agent, or may contain two or more kinds of translucency adjusting agents.

The amount of the translucent adjusting agent used is not particularly limited and can be appropriately adjusted according to the type of the translucent adjusting agent and the intended use of the finally obtained zirconia sintered body, but it is finally obtained. From the viewpoint of using the zirconia sintered body as a dental material, the content of the translucency adjusting agent in the composition is preferably 0.1% by mass or less with respect to the mass of zirconia.

-Organic solvent The composition used for stereolithography may contain an organic solvent. The viscosity of the composition can be adjusted by including an organic solvent. The type of organic solvent used is not particularly limited, and for example, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-2-propanol, 2-methoxyethanol, 2- Alcohols such as ethoxyethanol, 2- (2-ethoxyethoxy) ethanol, diethylene glycol monobutyl ether, glycerin; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran, diethyl ether, diisopropyl ether, 1,4-dioxane and dimethoxyethane (propylene) Contains modified ethers such as glycol monomethyl ether acetate (commonly known as "PGMEA") (preferably ether-modified ethers and / or ester-modified ethers, more preferably ether-modified alkylene glycols and / or ester-modified alkylene glycols). Examples include ethers such as ethyl acetate and butyl acetate; hydrocarbons such as hexane and toluene; halogenated hydrocarbons such as chloroform and carbon tetrachloride. These organic solvents may be used alone or in combination of two or more. Among these, in consideration of both safety to the living body and ease of removal, the organic solvent is preferably a water-soluble organic solvent, and specifically, ethanol, 2-propanol, 2-methyl-2-. More preferably, propanol, 2-ethoxyethanol, 2- (2-ethoxyethoxy) ethanol, propylene glycol monomethyl ether acetate, acetone and tetrahydrofuran. When the composition used for stereolithography contains an organic solvent, it is preferable to perform drying to remove the solvent after stereolithography.

The content of the organic solvent in the composition to be subjected to stereolithography is preferably 50% by mass or less, more preferably 30% by mass or less, from the viewpoint of keeping the viscosity in an appropriate range. It is more preferably mass% or less.

-Other components The composition used for stereolithography is composed of components other than the above-mentioned zirconia particles, polymerizable monomer, photopolymerization initiator, fluorescent agent, colorant, translucency adjuster and organic solvent. It may further contain one or more of them. Examples of such other components include binders, plasticizers, dispersants, emulsifiers, defoamers, pH adjusters, lubricants and the like. Further, it may be an antioxidant, a thickener, a leveling agent or the like. By including such other components, it may be possible to improve the monodispersity of the zirconia particles.

Examples of the binder include polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, acrylic binder, wax binder, polyvinyl butyral, polymethyl methacrylate, ethyl cellulose and the like.

Examples of the plasticizer include polyethylene glycol, glycerin, propylene glycol, dibutyl phthalate and the like.

Examples of the dispersant include ammonium polycarboxylate (triammonium citrate, etc.), ammonium polyacrylate, acrylic copolymer resin, acrylic acid ester copolymer, polyacrylic acid, bentonite, carboxymethyl cellulose, and anionic surfactant. Examples thereof include agents (for example, polyoxyethylene alkyl ether phosphates such as polyoxyethylene lauryl ether phosphates), nonionic surfactants, olein glycerides, amine surfactants, oligosaccharide alcohols and the like.

Examples of the emulsifier include alkyl ethers, phenyl ethers, sorbitan derivatives, ammonium salts and the like.

Examples of the defoaming agent include alcohol, polyether, polyethylene glucol, silicone, wax and the like.

Examples of the pH adjuster include ammonia, ammonium salts (including ammonium hydroxide such as tetramethylammonium hydroxide), alkali metal salts, alkaline earth metal salts and the like.

Examples of the lubricant include polyoxyethylene alkylate ether and wax.

-Preparation of a composition containing zirconia particles and a polymerizable monomer The method for preparing a composition containing zirconia particles and a polymerizable monomer to be subjected to photomolding is not particularly limited, and for example, with a powder containing zirconia particles. Although it can be obtained by mixing the polymerizable monomer, it has a step of mixing the slurry containing the zirconia particles with the polymerizable monomer because the monodispersity of the zirconia particles can be improved. It is preferably prepared by the method.

The slurry containing the zirconia particles mixed with the polymerizable monomer may be obtained through the breakdown process or the building-up process described above, or may be commercially available.

The slurry containing the zirconia particles mixed with the polymerizable monomer may be a slurry in which the dispersion medium is water, but since the monodispersity of the zirconia particles can be improved, an organic solvent or the like can be used. A slurry of a dispersion medium other than water is preferable. As the organic solvent, the above-mentioned organic solvent can be used as the organic solvent that can be contained in the composition used for stereolithography.

The content of the organic solvent in the dispersion medium is preferably 50% by mass or more, more preferably 80% by mass or more, and 95% by mass, because the monodispersity of the zirconia particles can be improved. The above is more preferable, and 99% by mass or more is particularly preferable.

A slurry of a dispersion medium other than water can be obtained by substituting the dispersion medium with respect to the slurry in which the dispersion medium is water. The method for replacing the dispersion medium is not particularly limited, and for example, a method of adding a dispersion medium (organic solvent or the like) other than water to the slurry in which the dispersion medium is water and then distilling off the water can be adopted. In distilling water, a part or all of the dispersion medium other than water may be distilled together. The addition of the dispersion medium other than the water and the distillation of water may be repeated a plurality of times. It is also possible to adopt a method of precipitating the dispersoid after adding a dispersion medium other than water to the slurry in which the dispersion medium is water. Further, for a slurry in which the dispersion medium is water, the dispersion medium may be replaced with a specific organic solvent, and then the slurry may be replaced with another organic solvent.

When a fluorescent agent is contained in the composition to be subjected to photoforming, the fluorescent agent may be added to a slurry of a dispersion medium other than water, or dispersion before replacing the dispersion medium. It may be added to a slurry whose medium is water. Similarly, when the composition to be subjected to stereolithography contains a colorant and / or a translucency adjusting agent, it may be added to a slurry of a dispersion medium other than water, or the dispersion medium may be replaced. It may be added to the slurry in which the dispersion medium is water.

The method of adding the fluorescent agent is not particularly limited, and a powdered fluorescent agent may be added, but a slurry containing zirconia particles (the dispersion medium may be water or the above-mentioned organic solvent) and a liquid state. It is preferable to carry out by mixing with the fluorescent agent of. As a result, it is possible to obtain a zirconia sintered body having excellent translucency and strength even though it contains a fluorescent agent, for example, by preventing the mixing of coarse particles. As the fluorescent agent in a liquid state, for example, a solution or a dispersion of the fluorescent agent can be used, and a solution of the fluorescent agent is preferable. The type of the solution is not particularly limited, and examples thereof include an aqueous solution. The aqueous solution may be a dilute nitric acid solution, a dilute hydrochloric acid solution, or the like, and can be appropriately selected depending on the type of fluorescent agent used and the like. As the colorant and / or the translucency adjuster, powders may be added, respectively, but it is preferable to mix the colorant and / or the translucency adjuster in a liquid state such as a solution or a dispersion with a slurry containing zirconia particles.

The slurry containing the zirconia particles mixed with the polymerizable monomer may be subjected to a dispersion treatment by heat or pressure such as reflux treatment and hydrothermal treatment. The slurry containing the zirconia particles mixed with the polymerizable monomer is mechanically dispersed by a roll mill, a colloid mill, a high-pressure injection disperser, an ultrasonic disperser, a vibration mill, a planetary mill, a bead mill, or the like. It may be the one that has been done. Only one of the above processes may be adopted, or two or more types may be adopted.

The mixing method for mixing the slurry containing the zirconia particles and the polymerizable monomer is not particularly limited, and a known method can be appropriately adopted. Further, after mixing, if necessary, a part or all of the dispersion medium contained in the slurry used for mixing may be removed by distillation or the like.

-Stereolithography step The method for producing a zirconia molded product of the present invention includes a step of stereolithography using the composition containing the above-mentioned zirconia particles and the polymerizable monomer. The specific method of stereolithography is not particularly limited, and a known method can be appropriately adopted for stereolithography. For example, a method of obtaining a target zirconia molded product by sequentially forming each layer having a desired shape by photopolymerizing a liquid composition with an ultraviolet ray, a laser, or the like using a stereolithography apparatus is adopted. be able to.

More specific examples of the stereolithography method include, for example, a free liquid level method, a regulated liquid level method, and the like, and the regulated liquid level method is preferable because the effect of the present invention is more prominently exhibited.

In the free liquid level method, the layer is locally cured by irradiating the composition with light from the upper side of the container containing the composition to be subjected to stereolithography, and the zirconia molded product is sequentially formed layer by layer. In this process, a composition for precipitating a cured layer formed near the liquid surface of the composition contained in the container in the composition by one layer to form the next layer on the cured layer. Is arranged using a recorder or the like as necessary, and the operation of irradiating the arranged composition with light is repeated.

On the other hand, in the regulated liquid level method, a zirconia molded product is formed by locally curing the layer by irradiating the composition with light from the lower side of the container containing the composition to be subjected to stereolithography through the bottom surface of the container. Are formed layer by layer. In this process, the cured layer is raised by one layer, a composition for forming the next layer is flowed between the lower surface of the cured layer and the bottom surface of the container, and light is applied to the flowed composition. Repeat the operation of irradiating.

In both the free liquid level method and the regulated liquid level method, it is desired to irradiate light according to the slice data for each layer based on the three-dimensional CAD data corresponding to the three-dimensional shape of the target dental material such as artificial teeth. It is possible to produce a zirconia molded product having the shape of. The shape (including size) of the zirconia molded product is preferably determined in consideration of shrinkage during subsequent calcining and sintering.

As the container used in the regulated liquid level method, a container in which at least a part of the bottom surface is optically transparent can be used. The entire bottom surface of the container may be formed of a light-transmitting material, or the peripheral portion of the bottom surface is formed of a material that does not transmit light, and the central portion surrounded by the peripheral portion is light-transmitting. It may be formed from a material, and the area of the optically transparent portion on the bottom surface of the container can be determined according to the size of the target dental material and the like. Examples of the light-transmitting material include transparent glass and transparent plastic.

In both the free liquid level method and the regulated liquid level method, there is no particular limitation on the type of light used for stereolithography, and an appropriate selection is made according to the type of each component in the composition used for stereolithography. However, the light is preferably ultraviolet rays or visible light having a wavelength of 300 to 450 nm because a zirconia molded product having a desired shape can be manufactured with higher accuracy. As a light source at that time, for example, various lasers (for example, a semiconductor-pumped solid-state laser that generates ultraviolet rays, an Ar laser, a He-Cd laser, an ultraviolet LED laser (light emitting diode), and an LED that emits light having a wavelength of 380 to 450 nm). Lasers, etc.), high-pressure mercury lamps, ultra-high pressure mercury lamps, low-pressure mercury lamps, xenon lamps, halogen lamps, metal halide lamps, ultraviolet LED lamps, ultraviolet fluorescent lamps, and the like. Of these, an LED laser or LED lamp that emits light having a wavelength of about 400 nm (generally about 380 to 410 nm) is particularly preferable from the viewpoint of convenience, economy, maintainability, and the like of the apparatus.

In both the free liquid level method and the regulated liquid level method, when the composition is irradiated with light to locally cure the layer, the composition is irradiated with light focused in dots such as laser light. A method of curing by a line drawing method may be adopted, or light passing through a planar drawing mask formed by arranging a plurality of micro light shutters such as a liquid crystal shutter and a digital micromirror shutter (DMD) is composed. A method of irradiating an object in a planar manner to cure it may be adopted.

The zirconia molded product produced by the production method of the present invention is for forming a dental material. Specifically, the zirconia molded body is calcined to obtain a zirconia calcined body (zirconia calcined body for forming dental materials) and then sintered to obtain a zirconia sintered body, or the zirconia is obtained. A zirconia sintered body can be produced by directly sintering the molded body to obtain a zirconia sintered body, and this zirconia sintered body can be used as a dental material such as an artificial tooth. Before calcining or sintering, the support portion attached to the zirconia molded product may be separated or the shape may be modified. Further, the zirconia sintered body obtained after sintering may be used as a dental material after undergoing morphological modification, surface polishing and the like, if necessary. When used as a dental material, it can be worn in the patient's oral cavity using dental cement.

[Zirconia molded product]
The present invention includes a zirconia molded product for forming a dental material obtained by the above-mentioned method for producing a zirconia molded product.

The content of itria contained in the zirconia molded product may be the same as the content of itria in the target zirconia sintered body, and the specific content of itria in the zirconia molded product is, for example, 2 mol% or more. It can be 3 mol% or more, more preferably 4 mol% or more, further preferably 4.5 mol% or more, 5 mol% or more, and further 5.5. It may be mol% or more, preferably 9 mol% or less, more preferably 8 mol% or less, still more preferably 7 mol% or less. The yttria content in the zirconia molded product means the ratio (mol%) of the number of moles of yttria to the total number of moles of zirconia and yttria.

When the zirconia sintered body contains a fluorescent agent, it is preferable that the zirconia molded product contains such a fluorescent agent. The content of the fluorescent agent in the zirconia molded product can be appropriately adjusted according to the content of the fluorescent agent in the obtained zirconia sintered body and the like. The specific content of the fluorescent agent contained in the zirconia molded product is 0.001% by mass or more in terms of the oxide of the metal element contained in the fluorescent agent with respect to the mass of the zirconia contained in the zirconia molded product. It is preferably 0.005% by mass or more, further preferably 0.01% by mass or more, and preferably 1% by mass or less, and 0.5% by mass or less. It is more preferable, and it is further preferable that it is 0.1% by mass or less.

When the zirconia sintered body contains a colorant, it is preferable that the zirconia molded product contains such a colorant. The content of the colorant in the zirconia molded product can be appropriately adjusted according to the content of the colorant in the obtained zirconia sintered body and the like. The specific content of the colorant contained in the zirconia molded body is 0.001% by mass or more in terms of oxide of the metal element contained in the colorant with respect to the mass of zirconia contained in the zirconia molded body. It is preferably 0.005% by mass or more, further preferably 0.01% by mass or more, preferably 5% by mass or less, and preferably 1% by mass or less. More preferably, it is 0.5% by mass or less, more preferably 0.1% by mass or less, and further preferably 0.05% by mass or less.

When the zirconia sintered body contains a translucency adjusting agent, it is preferable that the zirconia molded product contains such a translucency adjusting agent. The content of the translucency adjusting agent in the zirconia molded product can be appropriately adjusted according to the content of the translucency adjusting agent in the obtained zirconia sintered body and the like. The specific content of the translucency adjusting agent contained in the zirconia molded product is preferably 0.1% by mass or less with respect to the mass of zirconia contained in the zirconia molded product.

The density of the zirconia molded product is not particularly limited and varies depending on the manufacturing method of the zirconia molded product, etc., but the density is 3.0 g / cm ³ or more because a more dense zirconia sintered body can be obtained. It is preferably 3.2 g / cm ³ or more, and even more preferably 3.4 g / cm ³ or more. The upper limit of the density is not particularly limited, but may be, for example, 6.0 g / cm ³ or less, and further 5.8 g / cm ³ or less.

From the viewpoint of handleability and the like, the zirconia molded product preferably has a biaxial bending strength in the range of 2 to 10 MPa, more preferably in the range of 5 to 8 MPa. The biaxial bending strength of the zirconia molded product can be measured in accordance with JIS T 6526: 2012.

[Manufacturing method of zirconia calcined body]
By calcining the above-mentioned zirconia molded product for forming a dental material, a zirconia calcined product for forming a dental material can be obtained. By the calcining, the resin component generated by stereolithography can be removed. The calcining may be performed as a separate operation from the subsequent sintering, or may be included as a part of the heating operation when performing the sintering.

The calcining temperature is preferably 200 ° C. or higher, more preferably 300 ° C. or higher, and even more preferably 350 ° C. or higher, from the viewpoint that the desired zirconia calcined product can be easily obtained. , 400 ° C. or higher, further 500 ° C. or higher, preferably less than 900 ° C., more preferably 850 ° C. or lower, and even more preferably 800 ° C. or lower. When the calcination temperature is equal to or higher than the above lower limit, the generation of organic residue can be effectively suppressed.

The rate of temperature rise during calcination is not particularly limited, but it is desirable to slowly heat from 100 ° C. to 400 ° C. from the viewpoint of suppressing the occurrence of cracks. The specific rate of temperature rise is preferably 10 ° C./min or less, and more preferably 5 ° C./min or less. Further, from the viewpoint of suppressing cracks and deformation, a slower temperature rise rate is desirable in the range of 200 ° C. to 250 ° C. at which denaturation and incineration of the resin component substantially starts, and specifically, 2 ° C./min. It is preferably 1 ° C./min or less, and more preferably 1 ° C./min or less.

The calcination can be performed using a calcination furnace. The type of the calcining furnace is not particularly limited, and for example, an electric furnace and a degreasing furnace used in the general industry can be used.

[Zirconia calcined body]
The present invention includes a zirconia calcined product for forming a dental material obtained by the above-mentioned method for producing a zirconia calcined product.

The content of itria contained in the zirconia calcined product may be the same as the content of itria in the target zirconia sintered body, and the specific content of itria in the zirconia calcined product is, for example, 2 mol. % Or more, preferably 3 mol% or more, more preferably 4 mol% or more, further preferably 4.5 mol% or more, 5 mol% or more, and further 5 It may be 5.5 mol% or more, preferably 9 mol% or less, more preferably 8 mol% or less, still more preferably 7 mol% or less. The yttria content in the zirconia calcined product means the ratio (mol%) of the number of moles of yttria to the total number of moles of zirconia and yttria.

When the zirconia sintered body contains a fluorescent agent, it is preferable that the zirconia calcined product contains such a fluorescent agent. The content of the fluorescent agent in the zirconia calcined product can be appropriately adjusted according to the content of the fluorescent agent in the obtained zirconia sintered body and the like. The specific content of the fluorescent agent contained in the zirconia calcined body is 0.001% by mass or more in terms of the oxide of the metal element contained in the fluorescent agent with respect to the mass of the zirconia contained in the zirconia calcined body. It is preferably 0.005% by mass or more, further preferably 0.01% by mass or more, and preferably 1% by mass or less, and 0.5% by mass or less. It is more preferable that it is 0.1% by mass or less.

When the zirconia sintered body contains a colorant, it is preferable that the zirconia calcined body contains such a colorant. The content of the colorant in the zirconia calcined product can be appropriately adjusted according to the content of the colorant in the obtained zirconia sintered body and the like. The specific content of the colorant contained in the zirconia calcined body is 0.001% by mass or more in terms of the oxide of the metal element contained in the colorant with respect to the mass of the zirconia contained in the zirconia calcined body. It is preferably 0.005% by mass or more, further preferably 0.01% by mass or more, and preferably 5% by mass or less, and 1% by mass or less. More preferably, it is more preferably 0.5% by mass or less, and it may be 0.1% by mass or less, further more preferably 0.05% by mass or less.

When the zirconia sintered body contains a translucency adjusting agent, it is preferable that the zirconia calcined body contains such a translucency adjusting agent. The content of the translucency adjusting agent in the zirconia calcined product can be appropriately adjusted according to the content of the translucency adjusting agent in the obtained zirconia sintered body and the like. The specific content of the translucency adjusting agent contained in the zirconia calcined product is preferably 0.1% by mass or less with respect to the mass of zirconia contained in the zirconia calcined product.

There is no particular restriction on the density of the zirconia calcined body, etc. but the production method of zirconia molded body used in the preparation, it is preferably in the range of 3.0~6.0g / m ^{3, 3} More preferably, it is in the range of .2 to 5.8 g / m ^3.

The three-point bending strength of the zirconia calcined product is not particularly limited, and may be, for example, in the range of 10 to 70 MPa, and further in the range of 20 to 60 MPa. The three-point bending strength of the zirconia calcined body can be measured for a test piece of 5 mm × 40 mm × 10 mm under the conditions of a span length of 30 mm and a crosshead speed of 0.5 mm / min using a universal testing machine. ..

[Manufacturing method of zirconia sintered body]
A zirconia sintered body for dental materials can be obtained by sintering the above-mentioned zirconia molded product or zirconia calcined product for forming dental materials under normal pressure. In both the case of sintering the zirconia molded body and the case of sintering the zirconia calcined body, the sintering temperature is 900 ° C. or higher from the viewpoint that the target zirconia sintered body can be easily obtained. It is preferably 1000 ° C. or higher, more preferably 1050 ° C. or higher, further preferably 1200 ° C. or lower, more preferably 1150 ° C. or lower, and 1120 ° C. or lower. Is even more preferable. When the sintering temperature is at least the above lower limit, the sintering can proceed sufficiently, and a more dense sintered body can be easily obtained. Further, when the sintering temperature is not more than the above upper limit, it is possible to suppress the crystal particle size from becoming excessive, and the translucency of the obtained zirconia sintered body is improved, and when a fluorescent agent is contained. The deactivation can be suppressed.

In both the case of sintering the zirconia molded body and the case of sintering the zirconia calcined body, there is no particular limitation on the sintering time, but the target zirconia sintered body is productively and efficiently stabilized. The sintering time is preferably 5 minutes or more, more preferably 15 minutes or more, further preferably 30 minutes or more, and 6 hours or less because it can be obtained. It is preferably 4 hours or less, more preferably 2 hours or less.

Sintering can be performed using a sintering furnace. The type of the sintering furnace is not particularly limited, and for example, an electric furnace and a degreasing furnace used in the general industry can be used. In addition to the conventional sintering furnace for dental zirconia, dental porcelain furnaces having a relatively low sintering temperature can also be used.

The zirconia sintered body can be easily produced without the hot isotropic pressure pressurization (HIP) treatment, but the hot isotropic pressure pressurization (HIP) treatment is performed after the sintering under the above normal pressure. It is possible to further improve the translucency and strength.

[Zirconia sintered body]
The present invention includes a zirconia sintered body for dental materials obtained by the above-mentioned method for producing a zirconia sintered body.

The content of itria contained in the zirconia sintered body can be, for example, 2 mol% or more, and 3 mol% or more, because the zirconia sintered body is excellent in translucency and strength. Preferably, it is 4 mol% or more, more preferably 4.5 mol% or more, 5 mol% or more, further 5.5 mol% or more, and 9 mol%. It is preferably less than or equal to, more preferably 8 mol% or less, still more preferably 7 mol% or less. The yttria content in the zirconia sintered body means the ratio (mol%) of the number of moles of yttria to the total number of moles of zirconia and yttria.

The zirconia sintered body may contain a fluorescent agent. The zirconia sintered body is fluorescent because it contains a fluorescent agent. The content of the fluorescent agent in the zirconia sintered body is not particularly limited and can be appropriately adjusted according to the type of the fluorescent agent and the application of the zirconia sintered body, but from the viewpoint of use as a dental material, zirconia is used. The amount of zirconia contained in the sintered body is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, in terms of oxide of the metal element contained in the fluorescent agent. , 0.01% by mass or more, more preferably 1% by mass or less, more preferably 0.5% by mass or less, and further preferably 0.1% by mass or less. preferable. When the content is at least the above lower limit, the fluorescence is not inferior to that of natural human teeth, and when the content is at least the above upper limit, the translucency and intensity are lowered. Can be suppressed.

The zirconia sintered body may contain a colorant. The zirconia sintered body becomes a colored zirconia sintered body by containing a colorant. The content of the colorant in the zirconia sintered body is not particularly limited and can be appropriately adjusted according to the type of the colorant and the application of the zirconia sintered body, but from the viewpoint of use as a dental material, zirconia The amount of zirconia contained in the sintered body is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, in terms of oxide of the metal element contained in the colorant. , 0.01% by mass or more, more preferably 5% by mass or less, more preferably 1% by mass or less, still more preferably 0.5% by mass or less. It may be 0.1% by mass or less, and further may be 0.05% by mass or less.

In order to adjust the translucency of the zirconia sintered body, the zirconia sintered body may contain a translucency adjusting agent. The content of the translucency adjusting agent in the zirconia sintered body is not particularly limited and can be appropriately adjusted according to the type of the translucency adjusting agent and the use of the zirconia sintered body, but it is used as a dental material. From the above viewpoint, it is preferably 0.1% by mass or less with respect to the mass of zirconia contained in the zirconia sintered body.

The transmittance of light having a wavelength of 700 nm at a thickness of 0.5 mm of the zirconia sintered body obtained by the above production method is preferably 30% or more, preferably 35% or more, from the viewpoint of being more excellent in translucency. It is more preferably 40% or more, particularly preferably 45% or more, and may be 46% or more, 48% or more, 50% or more, and further 52% or more. By having such a transmittance, it is possible to obtain a dental material having more excellent aesthetics. The upper limit of the transmittance is not particularly limited, but the transmittance can be, for example, 60% or less, further 50% or less. The transmittance of light having a wavelength of 700 nm at a thickness of 0.5 mm of the zirconia sintered body may be measured using a spectrophotometer. For example, a spectrophotometer (manufactured by Hitachi High-Technologies Co., Ltd., “Hitachi Spectral Photometer” Using a meter U-3900H type), the light generated from the light source can be transmitted and scattered on the sample, and the measurement can be performed using an integrating sphere. In the measurement, the transmittance may be measured once in the wavelength region of 300 to 750 nm, and then the transmittance of light having a wavelength of 700 nm may be determined. As the sample used for the measurement, a 0.5 mm-thick zirconia sintered body having both sides mirror-polished can be used.

The crystal phase of the zirconia sintered body obtained by the above production method may be tetragonal, cubic, or a mixture of both.

The zirconia sintered body obtained by the above manufacturing method is used as a dental material for artificial teeth and the like.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples and the like. The method for measuring each physical property is as follows.

(1) Average primary particle size of zirconia particles The zirconia particles are photographed with a transmission electron microscope (TEM), and the particle size (maximum diameter) of each particle is measured for 100 arbitrary particles on the obtained image. , The average value thereof was taken as the average primary particle size of the zirconia particles.

(2) Monodispersity of zirconia particles The monodispersity of zirconia particles in the composition used for photoforming is 200 nm thick from the cured product obtained by photopolymerizing the composition with a dental light irradiator. The flakes were cut out using a microtome (“Reichert ULTRACUT-UCT” manufactured by Leica), and the flakes were photographed with a transmission electron microscope (JEOL, JEM2100F type) at a magnification of 100,000 and photographed. For all zirconia particles existing in the specified region in the field of view, the number of primary particles of all zirconia particles is set to X, and among these, the particles are monodispersed as primary particles without contacting each other and agglomerating. The number of zirconia particles was Y, and the degree of monodispersity was determined by the following formula.
Monodispersity (%) = 100 x Y / X
It should be noted that the region in the field of view taken so that the number of X's is about 300 is defined.

(3) Viscosity of composition used for stereolithography Measured at 25 ° C. using an E-type viscometer.

(4) Light transmittance (wavelength 700 nm, 0.5 mm thickness)
The transmittance of light at a wavelength of 700 nm at a thickness of 0.5 mm of a zirconia sintered body is determined by using a spectrophotometer (Hitachi High Technologies Co., Ltd., "Hitachi spectrophotometer U-3900H type") and light generated from a light source. Was transmitted and scattered in the sample, and measured using an integrating sphere. In the measurement, the transmittance was once measured in the wavelength region of 300 to 750 nm, and then the transmittance of light having a wavelength of 700 nm was determined. For the measurement, both sides of a 25 mm × 25 mm × 2 mm plate-shaped zirconia sintered body prepared by preparing the composition used in the following Examples or Comparative Examples according to the method described in the following Examples or Comparative Examples. Was mirror-polished to a thickness of 0.5 mm, and a test piece for measuring transmittance was used.

[Example 1]
(1) Propylene glycol as an organic solvent with respect to 200 parts by mass of an aqueous zirconia slurry "MELox Nanosize 5Y" (manufactured by MEL Chemicals, average primary particle diameter of zirconia particles 13 nm, zirconia concentration 23% by mass) containing 5 mol% of itria. 80 parts by mass of glycol monomethyl ether acetate (commonly known as "PGMEA") and 2 parts by mass of 2- (2- (2-methoxyethoxy) ethoxy) acetic acid (commonly known as "MEEAA") as a surface treatment agent were added to prepare a mixture. Was transferred to a round bottom flask and distilled off under reduced pressure using a rotary evaporator to distill off about 60 parts by mass of water and PGMEA. Toluene was added to the residue, and the mixture was subsequently distilled under reduced pressure in the same manner as described above to distill water, PGMEA and toluene as an azeotropic mixture. Water was sufficiently removed by repeating the operation of adding toluene to the residue and distilling the azeotropic mixture several times to obtain a fluid transparent slurry containing 50% by mass of zirconia particles. The main component of the dispersion medium in this slurry is PGMEA.

(2) With respect to 50 parts by mass of the obtained slurry, 8 parts by mass of triethylene glycol dimethacrylate (commonly known as "TEGDMA"), 2,2,4-trimethylhexamethylene bis (2-carbamoyloxyethyl) dimethacrylate [2 , 2,4-trimethylhexamethylene diisocyanate added at a ratio of 2 mol to 2 mol of 2-hydroxyethyl methacrylate; 12 parts by mass of [commonly known as "UDMA"], and 2,4,6- as a photopolymerization initiator. 0.1 part by mass of trimethylbenzoyldiphenylphosphine oxide (commonly known as "TPO") was added, and the mixture was uniformly mixed and dissolved. A dilute hydrochloric acid solution of bismuth acetate oxide as a fluorescent agent was further added thereto and mixed so that the content _{of bismuth oxide (Bi 2} O _{3) in terms of the mass of zirconia was 0.01% by mass.} This was concentrated using a rotary evaporator so as to have a total amount of 48 parts by mass to obtain a composition containing zirconia particles, a polymerizable monomer, a photopolymerization initiator and a fluorescent agent. The content of the zirconia particles in this composition was 52% by mass, the viscosity at 25 ° C. was 4,800 mPa · s, and the monodispersity of the zirconia particles was 75%.

(3) Using the above composition, stereolithography was performed by a regulated liquid level method to obtain a zirconia molded product having the shape of an artificial tooth. Specifically, using a commercially available stereolithography device (manufactured by DWS, "Digital Wax" 020D type), the laser output is 30 mW, the wavelength is 405 nm, the beam diameter is 0.02 mm, and the laser scanning speed is 4,600 mm / sec. The thickness was set to 0.05 mm, and stereolithography was performed using the three-dimensional CAD data of the maxillary first molar to obtain a laminated cured product corresponding to the first molar crown. This was left in air at room temperature for 5 days and dried to obtain a zirconia molded product.

(4) The obtained zirconia molded product was calcined under normal pressure using an electric furnace (Kuraray Noritake Dental Co., Ltd., "Katana F-1N") to obtain a zirconia calcined product. The calcining is heated from room temperature to 200 ° C. at a rate of 0.3 ° C./min, then from 200 ° C. to 260 ° C. at a rate of 0.1 ° C./min, and further to 0.3 ° C. This was done by raising the temperature from 260 ° C. to 400 ° C. at a rate of / min. This zirconia calcined product was placed in an electric furnace again, heated to 1050 ° C. at a rate of 60 ° C./hour under normal pressure, and sintered to obtain a dense molar-shaped zirconia sintered body. A test piece for measuring transmittance obtained from a 25 mm × 25 mm × 2 mm plate-shaped zirconia sintered body produced under the same conditions as above, according to the above method, light having a wavelength of 700 nm at a thickness of 0.5 mm. When the transmittance of the material was measured, it was 41%. By surface polishing and morphological modification of the above-mentioned molar-shaped zirconia sintered body, a translucent and aesthetically pleasing molar-shaped artificial tooth was obtained.

[Comparative Example 1]
(1) The water-based zirconia slurry used in Example 1 was dried using a spray dryer to obtain a powder containing zirconia particles.
(2) On the other hand, as a surface treatment agent, 8 parts by mass of 2- (2- (2-methoxyethoxy) ethoxy) acetic acid (commonly known as "MEEAA"), 32 parts by mass of triethylene glycol dimethacrylate (commonly known as "TEGDMA"), 2, 48 parts by mass of 2,4-trimethylhexamethylenebis (2-carbamoyloxyethyl) dimethacrylate (commonly known as "UDMA"), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (commonly known as "TPO") as a photopolymerization initiator 0 .3 parts by mass and a dilute hydrochloric acid solution of bismuth acetate oxide as a fluorescent agent, and _{the content of bismuth oxide (Bi 2} O ₃ ) equivalent to the mass of zirconia in the final composition is 0.01 part by mass. It was added and mixed so as to be. 100 parts by mass of the powder containing the above zirconia particles is added thereto and mixed uniformly using a three-roller to obtain a composition containing the zirconia particles, a polymerizable monomer, a photopolymerization initiator and a fluorescent agent. rice field. The content of the zirconia particles in this composition was 52% by mass, the viscosity at 25 ° C. was 4,300 mPa · s, and the monodispersity of the zirconia particles was 46%.
(3) Using the above composition, a zirconia molded product having an artificial tooth shape is obtained by the same method as in Example 1, and further, a zirconia calcined product and a zirconia sintered body are obtained by the same method as in Example 1. Obtained. In Comparative Example 1, the transmittance measurement test piece obtained from a 25 mm × 25 mm × 2 mm plate-shaped zirconia sintered body produced under the same conditions as described above has a wavelength at a thickness of 0.5 mm according to the above method. The transmittance of light at 700 nm was measured and found to be 22%, which was significantly lower than that of Example 1.

Claims (18)

A method for producing a zirconia molded product for forming a dental material, which comprises a step of stereolithography using a composition containing zirconia particles and a polymerizable monomer, and the average primary particle size of the zirconia particles is 30 nm or less. ,
Zirconia particles contain 3-9 mol% yttria relative to the total number of moles of zirconia and yttria.
The composition is produced by a method having a step of mixing a slurry containing zirconia particles and a polymerizable monomer, and the slurry is a slurry of a dispersion medium other than water.
The dispersion medium contains 80% by mass or more of an organic solvent, and contains 80% by mass or more.
A production method in which the monodispersity of zirconia particles is 70% or more. The production method according to claim 1, wherein the zirconia particles contain 4.5 to 7 mol% of yttria. The production method according to claim 1 or 2, wherein the organic solvent is at least one organic solvent selected from the group consisting of alcohols, ketones, ethers, modified ethers, esters, hydrocarbons, and halogenated hydrocarbons. The production method according to any one of claims 1 to 3, wherein the polymerizable monomer is a radically polymerizable monomer. The production method according to any one of claims 1 to 4, wherein the composition comprises a photopolymerization initiator. The production method according to any one of claims 1 to 5, wherein the composition contains 20 to 90% by mass of zirconia particles. The production method according to any one of claims 1 to 6, wherein the composition has a viscosity at 25 ° C. of 20,000 mPa · s or less. The production method according to any one of claims 1 to 7, wherein the composition further comprises a fluorescent agent. The production method according to any one of claims 1 to 8, wherein the zirconia particles are surface-treated with a surface treatment agent. The manufacturing method according to any one of claims 1 to 9, which is stereolithographically formed by the regulated liquid level method. A method for producing a zirconia calcined body for forming a dental material, which comprises a step of calcining the zirconia molded body for forming a dental material obtained by the production method according to any one of claims 1 to 10. The production method according to claim 11 , wherein the calcination is performed at 200 ° C. or higher and lower than 900 ° C. A method for producing a zirconia sintered body for dental materials, which comprises a step of sintering a zirconia molded body for forming a dental material obtained by the production method according to any one of claims 1 to 10 under normal pressure. The production method according to claim 13 , wherein sintering is performed at 900 ° C. or higher and 1200 ° C. or lower. A method for producing a zirconia sintered body for dental materials, which comprises a step of sintering a zirconia calcined product for forming a dental material obtained by the production method according to claim 11 or 12 under normal pressure. The production method according to claim 15 , wherein sintering is performed at 900 ° C. or higher and 1200 ° C. or lower. The production method according to any one of claims 13 to 16 , wherein the zirconia sintered body has a light transmittance of 30% or more at a wavelength of 700 nm at a thickness of 0.5 mm. The production method according to any one of claims 13 to 17 , wherein the zirconia sintered body is an artificial tooth.