Unsintered zirconia composite and method for manufacturing same, dental mill blank, and method for manufacturing dental prosthesis

Abstract

The present invention provides an unfired zirconia composite and a dental mill blank, with which a dental prosthesis can be manufactured with a single sintering operation without a pre-sintering operation and which have appropriate strength to withstand machining. The present invention pertains to: an unfired zirconia composite composed of an unfired zirconia molded body and a resin, wherein the resin is embedded in the unfired zirconia molded body; and a dental mill blank including said unfired zirconia composite.

Description

[Technical Field]

[0001] The present invention relates to an unsintered zirconia composite and a method for producing the same, and more particularly to a dental mill blank that is suitable for use in producing dental prostheses such as inlays, onlays, veneers, crowns, bridges, abutments, dental posts, dentures, denture bases, and implant components (fixtures, abutments) by cutting using a dental CAD / CAM system. [Background technology]

[0002] Traditionally, metals have been commonly used for dental products (e.g., typical prosthetic devices such as veneers, dental crowns, crowns, and dental implants; orthodontic products; and dental implant products). However, metals have the drawback of being significantly different in color from natural teeth, resulting in poor aesthetics, and metal elution can also cause allergies. Therefore, to solve the problems associated with the use of metals, ceramic materials such as aluminum oxide (alumina) and zirconium oxide (zirconia) have been used in dental products as alternatives to metals. Zirconia, in particular, is strong and relatively aesthetically pleasing, and demand for it is increasing, especially as prices have fallen in recent years.

[0003] On the other hand, some types of products to which zirconia sintered bodies are applied require high dimensional accuracy. For example, in the case of artificial teeth used in dental treatment, the shape and dimensions of the artificial teeth must match the dimensions and shape of the patient's abutment teeth, data of which has been collected in advance, or the artificial teeth cannot be applied to the patient.

[0004] In recent years, CAD / CAM systems have become widespread, in which dental prostheses such as inlays and crowns are designed by computer and then milled using a milling machine. Traditionally, zirconia has been commonly used as the mill blank material for these systems, due to the emphasis on aesthetics. Zirconia mill blanks are generally porous calcined compacts (hereinafter also referred to as "calcined bodies") calcined once at temperatures of approximately 900 to 1200°C. To perform cutting and grinding on zirconia mill blanks using a CAD / CAM system, the zirconia mill blanks must have a certain strength. A calcination process within the aforementioned temperature range is generally considered necessary to impart the required physical properties, such as strength, to the zirconia mill blanks. However, because calcined zirconia mill blanks are brittle materials with high hardness, they can chip due to impacts during cutting and grinding. Furthermore, wet processing using a coolant can cause the required translucency, resulting in devitrification of dental prostheses after processing and re-firing.

[0005] To solve these problems, recent studies have focused on mill blanks made of composite materials containing polymer resins and inorganic fillers, including changes in the raw materials. Mill blanks made of such composite materials have excellent machinability and grindability during processing, and are therefore beginning to be processed into dental prostheses for clinical use.

[0006] For example, Patent Document 1 discusses a method for improving strength by infiltrating a porous support with a liquid resin, curing the resin impregnating the support, and applying a pressure of more than approximately 30 MPa (300 bar) to the resin, but does not discuss the use of zirconia.

[0007] Furthermore, Patent Document 2 studies a mill blank characterized by contacting an inorganic filler compact obtained by press-molding an inorganic filler with a polymerizable monomer-containing composition to polymerize and harden the polymerizable monomer, but the mill blank is used without sintering and is not intended to be sintered, meaning that the problems specific to zirconia mill blanks as calcined zirconia bodies are not studied. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Publication No. 2012-501783 [Patent Document 2] International Publication No. 2014 / 021343 Summary of the Invention [Problem to be solved by the invention]

[0009] Therefore, an object of the present invention is to provide an unsintered zirconia composite and a dental mill blank that can be used to manufacture dental prostheses by a single sintering operation without requiring a prior sintering operation, and that have an appropriate strength to withstand machining. Another object of the present invention is to provide an unsintered zirconia composite and a dental mill blank that have a hydrophobic surface that is not affected by cooling water even in wet processing and can be used suitably in wet processing. [Means for solving the problem]

[0010] As a result of extensive research to solve the above problems, the present inventors have found that the above problems can be solved by using a specific unsintered zirconia composite. Based on this finding, they have conducted further research and have completed the present invention.

[0011] That is, the present invention includes the following inventions. [1] An unsintered zirconia composite comprising an unsintered zirconia molded body and a resin, the unsintered zirconia molded body being infiltrated with the resin. [2] The unsintered zirconia composite according to [1], wherein the resin is a curable resin, a cured product of a curable resin, or a polymer. [3] The unsintered zirconia composite according to [1], wherein the resin is a thermoplastic resin. [4] The unsintered zirconia composite according to any one of [1] to [3], wherein the unsintered zirconia molded body contains 2 to 8 mol % of yttria. [5] The unsintered zirconia composite according to any one of [1] to [4], wherein the unsintered zirconia molded body contains 0.0001 to 10.0 mass % of an oxide as a colorant. [6] The unsintered zirconia composite according to any one of [1] to [5], wherein the average particle size of the zirconia is 0.001 to 10 μm, and the particle size range is 0.0005 to 50 μm. [7] The unsintered zirconia composite according to any one of [1] to [6], which has a biaxial bending strength of 20 to 140 MPa. [8] The unsintered zirconia composite according to any one of [1] to [7], which has a Vickers hardness of 5 to 140 Hv. [9] Step (1) of press-molding zirconia to obtain an unsintered zirconia molded body; and (2) a step of infiltrating the obtained unsintered zirconia molded body with a thermoplastic resin, a curable resin, a polymerizable monomer, or a composition containing a polymerizable monomer; A method for producing an unsintered zirconia composite, comprising:

[10] The method for producing an unsintered zirconia composite according to [9], wherein, in the step (2), a curable resin, a polymerizable monomer, or a composition containing a polymerizable monomer is infiltrated into an unsintered zirconia molded body, the method further comprises, after the step (2), a step (3) of curing the curable resin or the polymerizable monomer.

[11] The method for producing an unsintered zirconia composite according to

[10] , wherein in the step (3), curing is carried out in a vacuum state.

[12] The method for producing an unsintered zirconia composite according to

[10] , wherein in the step (3), curing is carried out under atmospheric pressure.

[13] The method for producing an unsintered zirconia composite according to

[10] , wherein in the step (3), curing is carried out under a pressure of 20 MPa or more.

[14] The method for producing an unsintered zirconia composite according to any one of

[10] to

[13] , wherein a thermal polymerization initiator, a photopolymerization initiator and / or a chemical polymerization initiator is contained together with the polymerizable monomer.

[15] The method for producing an unsintered zirconia composite according to any one of

[10] to

[14] , wherein the curing in the step (3) is thermal polymerization.

[16] The method for producing an unsintered zirconia composite according to [9], further comprising a step of molten the thermoplastic resin prior to step (2) when the thermoplastic resin is infiltrated into the unsintered zirconia molded body in step (2).

[17] The method for producing an unsintered zirconia composite according to any one of [9] to

[16] , wherein the press molding comprises a uniaxial press molding step and / or a cold isostatic pressing (CIP) step.

[18] A dental mill blank comprising the unsintered zirconia composite according to any one of [1] to [8].

[19] A dental mill blank according to

[18] , wherein the contact angle of the surface is 35° or more.

[20] A method for producing a dental prosthesis, comprising: a step (I) of machining the dental mill blank according to

[18] or

[19] ; ​​and a step (II) of sintering the green dental prosthesis.

[21] The method for producing a dental prosthesis according to

[20] , wherein in step (II), the unfired dental prosthesis is degreased at a temperature of 800°C or less. [Effects of the Invention]

[0012] The green zirconia composite of the present invention can be used to produce dental prostheses made of zirconia ceramics that meet the aesthetic requirements for dental prostheses. The green zirconia composite of the present invention can be used to produce dental prostheses through a single sintering operation, and can also produce green zirconia composites and dental mill blanks that have appropriate strength to withstand machining. Furthermore, because the green zirconia composite of the present invention has strength that can withstand machining, when used as a dental mill blank, it can suppress the occurrence of cracking or chipping during cutting. Furthermore, the green zirconia composite and dental mill blank of the present invention have hydrophobic surfaces that are not affected by coolants even in wet machining, making them suitable for use in wet machining. DETAILED DESCRIPTION OF THE INVENTION

[0013] The green zirconia composite of the present invention is composed of a green zirconia molded body and a resin, and it is important that the green zirconia molded body is infiltrated with the resin. The production method thereof is characterized by comprising the steps of: (1) press-molding zirconia to obtain a green zirconia molded body; and (2) infiltrating the obtained green zirconia molded body with a thermoplastic resin, a curable resin, a polymerizable monomer, or a composition containing a polymerizable monomer. The production method may also be performed by press-molding a mixture of zirconia and a resin component (thermoplastic resin or curable resin) or a resin raw material component (a polymerizable monomer or a composition containing a polymerizable monomer) (e.g., a composition obtained by adding a binder to a slurry containing zirconia powder) to obtain a green zirconia molded body. However, even in this case, a step of infiltrating the molded body with the resin component or resin raw material component is required. In this specification, the unsintered zirconia molded body after being infiltrated with the resin is referred to as an "unsintered zirconia composite" to be distinguished from the "unsintered zirconia molded body" before being infiltrated. Details will be explained below.

[0014] The green zirconia molded body of the present invention is a molded body made of unsintered, i.e., unsintered, zirconia. In the present invention, "unsintered" refers to a state in which contacting portions of zirconia powder particles have not reacted with each other.

[0015] The unsintered zirconia molded body of the present invention preferably contains a stabilizer because it is required to have chipping resistance, crack resistance, and bending strength sufficient to withstand repeated chewing movements when used as a dental prosthesis. That is, it is preferable to incorporate a stabilizer into zirconia before firing. This allows the fired zirconia sintered body, which serves as the base material for the dental prosthesis, to have at least one of partially stabilized zirconia and fully stabilized zirconia as a matrix phase. In the zirconia sintered body, the main crystalline phase of zirconia is at least one of tetragonal and cubic, and may contain both tetragonal and cubic. Furthermore, the zirconia sintered body preferably does not substantially contain a monoclinic phase. Substantially not containing a monoclinic phase means that the content of the monoclinic phase in the zirconia sintered body is less than 5.0% by mass, preferably less than 1.0% by mass. Zirconia that is partially stabilized by adding a stabilizer is called partially stabilized zirconia (PSZ), and zirconia that is fully stabilized is called fully stabilized zirconia. The green zirconia molded body of the present invention may be partially stabilized zirconia or fully stabilized zirconia. One preferred embodiment is an green zirconia composite that is composed of a green zirconia molded body and a resin, the green zirconia molded body being infiltrated with the resin, the green zirconia molded body containing partially stabilized zirconia stabilized with a stabilizer, and the stabilizer being yttria.

[0016] Examples of the stabilizer include yttrium oxide (Y2O3) (hereinafter referred to as "yttria"), calcium oxide (calcia; CaO), magnesium oxide (magnesia; MgO), cerium oxide (ceria; CeO2), scandium oxide (Sc2O3), niobium oxide (Nb2O5), lanthanum oxide (La2O3), erbium oxide (Er2O3), and praseodymium oxide (Pr6O 11 Preferably, the stabilizer is at least one oxide selected from the group consisting of yttria, samarium oxide (Sm2O3), europium oxide (Eu2O3), and thulium oxide (Tm2O3). Yttria is particularly preferred as a stabilizer from the viewpoints of high translucency and improved strength. These stabilizers may be used alone or in combination of two or more. According to the unsintered zirconia composite of the present invention, even when using zirconia containing a stabilizer such as partially stabilized zirconia, a dental mill blank can be obtained that has physical properties such as strength that can withstand machining such as cutting, and that can suppress the occurrence of cracking or chipping during machining such as cutting, without undergoing a typical calcination step. This solves the problems associated with conventional calcined zirconia bodies.

[0017] When yttria is contained as a stabilizer, the content of yttria in the unsintered zirconia molded body is preferably 2 to 8 mol %, more preferably 3 to 6 mol %, based on 100 mol % of the total of zirconia and stabilizer. This content can suppress phase transition to monoclinic crystals and increase the transparency of the zirconia sintered body.

[0018] When calcium oxide is contained as a stabilizer, the content of calcium oxide is preferably 2 to 15 mol %, more preferably 2.1 to 12 mol %, relative to 100 mol % of the total of zirconia and the stabilizer.

[0019] When magnesium oxide is contained as a stabilizer, the content of magnesium oxide is preferably 2 to 12 mol %, more preferably 2.1 to 10 mol %, relative to 100 mol % of the total of zirconia and the stabilizer.

[0020] When cerium oxide is contained as a stabilizer, the content of cerium oxide is preferably 2 to 18 mol %, more preferably 2.1 to 12 mol %, relative to 100 mol % of the total of zirconia and the stabilizer.

[0021] When scandium oxide is contained as a stabilizer, the content of scandium oxide is preferably 0.1 to 1 mol %, more preferably 0.1 to 0.3 mol %, relative to 100 mol % in total of zirconia and the stabilizer.

[0022] When niobium oxide is contained as a stabilizer, the content of niobium oxide is preferably 0.1 to 10 mol %, more preferably 0.1 to 7 mol %, relative to 100 mol % in total of zirconia and the stabilizer.

[0023] When lanthanum oxide is contained as a stabilizer, the content of lanthanum oxide is preferably 1 to 10 mol %, more preferably 2 to 7 mol %, relative to 100 mol % in total of zirconia and the stabilizer.

[0024] When erbium oxide is contained as a stabilizer, the content of erbium oxide is preferably 0.1 to 1 mol %, more preferably 0.1 to 0.3 mol %, relative to 100 mol % of the total of zirconia and the stabilizer.

[0025] When praseodymium oxide is contained as a stabilizer, the content of praseodymium oxide is preferably 0.1 to 1 mol %, more preferably 0.1 to 0.3 mol %, relative to 100 mol % in total of zirconia and the stabilizer.

[0026] When samarium oxide is contained as a stabilizer, the content of samarium oxide is preferably 0.1 to 1 mol %, more preferably 0.1 to 0.3 mol %, relative to 100 mol % in total of zirconia and the stabilizer.

[0027] When europium oxide is contained as a stabilizer, the content of europium oxide is preferably 0.1 to 1 mol %, more preferably 0.1 to 0.3 mol %, relative to 100 mol % in total of zirconia and the stabilizer.

[0028] When thulium oxide is contained as a stabilizer, the content of thulium oxide is preferably 0.1 to 1 mol %, more preferably 0.1 to 0.3 mol %, relative to 100 mol % in total of zirconia and the stabilizer.

[0029] The content of the stabilizer in the zirconia sintered body can be measured by, for example, inductively coupled plasma (ICP) emission spectroscopy, fluorescent X-ray analysis, or the like.

[0030] The green zirconia molded body of the present invention preferably contains a colorant to mimic the color of natural teeth. The colorant preferably contains an oxide. Examples of the oxide include known pigments used in dental applications (inorganic pigments, composite pigments, fluorescent pigments, etc.). Examples of inorganic pigments include oxides such as nickel oxide, iron oxide red, chromium oxide, aluminum oxide, and titanium oxide. Examples of composite pigments include oxides such as (Zr,V)O2, Fe(Fe,Cr)2O4, (Ni,Co,Fe)(Fe,Cr)2O4·ZrSiO4, and (Co,Zn)Al2O4. Examples of fluorescent pigments include Y2SiO5:Ce, Y2SiO5:Tb, (Y,Gd,Eu)BO3, Y2O3:Eu, YAG:Ce, ZnGa2O4:Zn, and BaMgAl. 10 O 17 Examples include oxides of Eu, etc. The oxide content in the unsintered zirconia molded body may be 0% by mass (no oxides included) as described above, but if oxides are included, it is preferably 10.0% by mass or less from the viewpoint of aesthetics. More specifically, it is preferably 0.0001 to 10.0% by mass, more preferably 0.001 to 9.0% by mass, and even more preferably 0.1 to 8.0% by mass.

[0031] The green zirconia molded body of the present invention can be produced by press-molding zirconia (preferably zirconia powder) as in step (1). The press-molding method for the zirconia raw material can be any known method without limitation, and may include, for example, a uniaxial press molding step and / or a cold isostatic pressing (CIP) step. A suitable uniaxial press molding step involves filling zirconia into a press mold (die) of a desired size and applying pressure by uniaxial pressing using an upper punch and a lower punch. The pressing pressure is set appropriately and optimally taking into account the size of the desired molded body, the particle size of the zirconia, and the like, and is usually 10 MPa or higher. If the pressing pressure is too low, the zirconia particles will not be densely packed, and the gaps between the zirconia particles will not be sufficiently narrow, making it difficult to increase the content of zirconia particles per unit volume in the resulting mill blank. As a result, from this perspective, the higher the pressing pressure, the better. However, taking into consideration productivity aspects such as the size of the press-molded product and equipment factors, the pressing pressure in a uniaxial press is usually 200 MPa or less, preferably 10 MPa or more, more preferably 20 MPa or more, even more preferably 25 MPa or more, and preferably 180 MPa or less, more preferably 150 MPa or less, even more preferably 100 MPa or less, and particularly preferably 80 MPa or less. It is also preferably in the range of 10 to 200 MPa, more preferably 20 to 100 MPa, and even more preferably 25 to 80 MPa. The pressing time can be set appropriately depending on the pressing pressure, but is usually 1 to 120 minutes.

[0032] When step (1) includes a CIP process, specifically, it is preferable to further subject the compact to CIP after the uniaxial press molding described above. CIP molding typically applies higher pressure than uniaxial press molding and applies pressure uniformly to the compact from three dimensions. Therefore, CIP molding can eliminate undesirable microvoids or uneven zirconia particle agglomeration within the compact, further increasing the compressed density of the zirconia particles and resulting in a mill blank with an extremely high zirconia particle content. Thus, when CIP molding is performed after uniaxial press molding, the pressed compact can be subjected to CIP processing either directly or after being placed in a vacuum. For example, a CIP device "Dr.CHEF" manufactured by Kobe Steel, Ltd., capable of applying a pressure of approximately 980 MPa, can be used for such CIP processing.

[0033] Furthermore, when the press molding includes a CIP process, a press-molded product can be obtained by filling zirconia into a highly elastic container made of silicone rubber, polyisoprene rubber, or the like, without going through the uniaxial pressing process using a mold, and then subjecting the container to CIP treatment either directly or under vacuum. A high pressure is also preferred during CIP molding.

[0034] High pressure is preferable during CIP molding, regardless of whether uniaxial pressing is used or not. However, taking productivity into consideration, when uniaxial pressing is used, the pressure is preferably 30 MPa or more, more preferably 50 MPa or more, even more preferably 100 MPa or more, and preferably 500 MPa or less, more preferably 400 MPa or less, and even more preferably 300 MPa or less. A pressure of 30 to 500 MPa is preferred, more preferably 50 to 400 MPa, and even more preferably 100 to 300 MPa is preferred. When CIP treatment is performed without uniaxial pressing, the pressure is preferably 30 MPa or more, more preferably 50 MPa or more, even more preferably 100 MPa or more, and preferably 1000 MPa or less, more preferably 800 MPa or less, and even more preferably 700 MPa or less. The pressure during CIP molding is preferably 30 to 1000 MPa, more preferably 50 to 800 MPa, and even more preferably 100 to 700 MPa. The CIP molding time can be appropriately set depending on the pressing pressure, but is typically 1 to 120 minutes.

[0035] In step (1), two or more different types of zirconia powder may be stacked and press-molded, as described below. For example, a first zirconia powder is filled into a uniaxial press die fitted with a lower punch, and an upper punch is set in the die to press the powder. The upper punch is then removed, and a second zirconia powder is filled on top of the pressed first zirconia powder aggregate. The upper punch is then set again to press the second zirconia powder. The pressed compact is then removed from the die to obtain a press-molded product in which the first zirconia particles and the second zirconia particles are layered. The press pressure during the press molding is appropriately set to an optimal value taking into account the type of zirconia particles used, the amount of colorant contained, and other factors. The press pressure for each layer may be different or the same. Alternatively, after the first zirconia powder is filled into the mold, the surface may be flattened and, without pressing, the second zirconia powder may be filled on top of it, and the first zirconia powder and the second zirconia powder may be pressed together.

[0036] The size of the green zirconia molded body (and green zirconia composite) of the present invention is not particularly limited, since it can be processed into dental mill blanks of various shapes described below. The green zirconia molded body of the present invention may be a molded body obtained by press-molding a zirconia raw material all at once, or may be a molded body obtained by stacking separately molded bodies and then press-molding the laminated body into a single body, or may be a molded body obtained by press-molding a new zirconia raw material onto a separately molded body.

[0037] The unsintered zirconia molded body obtained in step (1) can be infiltrated (and further cured as necessary) with a thermoplastic resin, a curable resin, a polymerizable monomer, or a composition containing a polymerizable monomer, as described below, so that the resin penetrates into the gaps between the powder primary particles, resulting in a composite with a structure in which zirconia particles are extremely densely dispersed in the resin. Therefore, in the present invention, it is preferable to use the zirconia raw material in the state in which it is press-molded. In other words, a sintered, interconnected porous body, as in Patent Document 1, is not preferable, and a molded body that is a densely packed body of zirconia powder is preferred.

[0038] The green zirconia composite of the present invention is obtained by infiltrating the above-mentioned green zirconia molded body with a resin. The resin is not limited as long as it achieves the effects of the present invention, but is preferably a curable resin, a cured product or polymer of a curable resin, or a thermoplastic resin. By infiltrating the green zirconia molded body with the resin, the green zirconia composite is not affected by contaminated water or oil containing inhibitory components that can reduce the aesthetics and strength of the finished product (e.g., a dental prosthesis such as a crown) after sintering. Furthermore, peeling of zirconia particles during processing of the microstructure can be suppressed, thereby improving processing reproducibility.

[0039] The polymer may be a compound derived from a polymerizable monomer, as described below. Examples of the thermoplastic resin include polyethylene (PE) such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE), ethylene copolymers such as copolymers of ethylene and vinyl acetate, and polyolefin resins such as polypropylene (PP); vinyl resins such as polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), and polyvinyl alcohol (PVA); polystyrene resins such as polystyrene (PS), acrylonitrile-styrene copolymer (AS), and acrylonitrile-butadiene-styrene copolymer (ABS); acrylic resins such as polymethyl methacrylate (PMMA) and methacrylate-styrene copolymer (MS); and polyester resins such as polybutylene terephthalate (PBT) and polyethylene terephthalate (PET). Examples of curable resins include epoxy resin (EP), phenolic resin (PF), unsaturated polyester resin (UP), urea resin (UF), melamine resin (MF), diallyl phthalate resin (PDAP), vinyl ester resin, polyimide, polyurethane (PU), silicone resin (SI), and alkyd resin.

[0040] Specifically, the ignition residue of a cured product can be measured by, for example, placing the cured product in a crucible and heating it in an electric furnace at 575°C for a predetermined time to burn off the organic resin component, and then measuring the mass of the remaining zirconia. In this method, in the case of a dental mill blank obtained using surface-treated zirconia powder, the applied surface treatment agent is calculated as the burned organic resin component.

[0041] When the resin infiltrated into the unsintered zirconia composite is a polymer, it is preferable to include a step (3) in which, in step (2), the unsintered zirconia molded body is infiltrated with a curable resin, a polymerizable monomer, or a composition containing a polymerizable monomer (hereinafter, polymerizable monomers and compositions containing polymerizable monomers may be collectively referred to as "polymerizable monomer-containing compositions"), and then the curable resin or the polymerizable monomer is cured.

[0042] The polymerizable monomer used in the present invention may be any known polymerizable monomer used in dental composite resins, etc., without any particular limitation. However, radically polymerizable monomers are generally preferred. Specific examples of radically polymerizable monomers include esters of α-cyanoacrylic acid, (meth)acrylic acid, α-halogenated acrylic acid, crotonic acid, cinnamic acid, sorbic acid, maleic acid, itaconic acid, etc., (meth)acrylamide, (meth)acrylamide derivatives, vinyl esters, vinyl ethers, mono-N-vinyl derivatives, styrene derivatives, etc. Among these, (meth)acrylic acid esters and (meth)acrylamide derivatives are preferred, and (meth)acrylic acid esters are more preferred. In this specification, the term "(meth)acrylic" is used to encompass both methacrylic and acrylic. Examples of (meth)acrylic acid ester-based and (meth)acrylamide derivative-based polymerizable monomers in the present invention are shown below.

[0043] (I) Monofunctional (meth)acrylate and (meth)acrylamide derivatives Methyl (meth)acrylate, isobutyl (meth)acrylate, benzyl (meth)acrylate, lauryl (meth)acrylate, 2-(N,N-dimethylamino)ethyl (meth)acrylate, 2,3-dibromopropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, propylene glycol mono(meth)acrylate, glycerin mono(meth)acrylate, erythritol mono( (meth)acrylate, N-methylol (meth)acrylamide, N-hydroxyethyl (meth)acrylamide, N,N-bis(2-hydroxyethyl) (meth)acrylamide, (meth)acryloyloxydodecylpyridinium bromide, (meth)acryloyloxydodecylpyridinium chloride, (meth)acryloyloxyhexadecylpyridinium chloride, (meth)acryloyloxydecylammonium chloride, 10-mercaptodecyl (meth)acrylate, and the like.

[0044] (II) Difunctional (meth)acrylate Ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, bisphenol A diglycidyl (meth)acrylate (2,2-bis[4-[3-(meth)acryloyloxy-2-hydroxypropoxy]phenyl]propane), 2,2-bis[4-(meth)acryloyloxyethoxy]phenyl]propane [diphenyl]propane, 2,2-bis[4-(meth)acryloyloxypolyethoxyphenyl]propane, 1,2-bis[3-(meth)acryloyloxy-2-hydroxypropoxy]ethane, pentaerythritol di(meth)acrylate, [2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)]dimethacrylate (commonly known as UDMA), 2,2,3,3,4,4-hexafluoro-1,5-pentyl dimethacrylate, tricyclodecane dimethanol di(meth)acrylate, and the like.

[0045] (III) Tri- or higher functional (meth)acrylates Examples of the acrylate include trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, N,N'-(2,2,4-trimethylhexamethylene)bis[2-(aminocarboxy)propane-1,3-diol]tetramethacrylate, and 1,7-diacryloyloxy-2,2,6,6-tetraacryloyloxymethyl-4-oxaheptane.

[0046] In addition to these (meth)acrylic acid ester and (meth)acrylamide derivative polymerizable monomers, cationically polymerizable oxirane compounds and oxetane compounds are also preferably used.

[0047] The polymerizable monomers may be used singly or in combination of two or more. The polymerizable monomers used in the present invention are preferably liquid, but do not necessarily need to be liquid at room temperature. They may be liquid under the conditions of the step in which the polymerizable monomer is brought into contact with a powder-formed press-molded body. Furthermore, even solid polymerizable monomers can be mixed and dissolved with other liquid polymerizable monomers for use.

[0048] The viscosity range (25°C) of the polymerizable monomer is preferably 10 Pa s or less, more preferably 5 Pa s or less, and even more preferably 2 Pa s or less. However, when two or more polymerizable monomers are mixed and dissolved or further diluted with a solvent, it is not necessary for each polymerizable monomer to be in the above viscosity range, and it is preferable that the viscosity of the polymerizable monomer be in the above viscosity range in the state of the mixed and dissolved composition to be used.

[0049] The content of the polymerizable monomer in the unsintered zirconia composite of the present invention can be appropriately adjusted depending on the degree of contact of the polymerizable monomer-containing composition with the unsintered zirconia composite. Furthermore, the content of the polymerizable monomer in the unsintered zirconia composite of the present invention varies depending on the average particle size of the zirconia particles constituting the unsintered zirconia composite or the press molding method, and therefore the content of the polymerizable monomer cannot be determined in general.

[0050] The green zirconia composite of the present invention is formed by polymerizing and curing the polymerizable monomer that has been infiltrated into the internal gaps of the green zirconia molded body. Therefore, the polymerizable monomer-containing composition may contain a polymerization initiator to facilitate polymerization and curing. The polymerization initiator can be selected from polymerization initiators used in general industry, and polymerization initiators used for dental applications are preferred. Polymerization initiators for thermal polymerization, photopolymerization, and chemical polymerization are preferably used alone or in appropriate combinations of two or more.

[0051] Examples of the thermal polymerization initiator include organic peroxides and azo compounds.

[0052] Examples of the organic peroxide used as the thermal polymerization initiator include ketone peroxides, hydroperoxides, diacyl peroxides, dialkyl peroxides, peroxyketals, peroxyesters, and peroxydicarbonates.

[0053] Examples of the ketone peroxide used as the thermal polymerization initiator include methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, methylcyclohexanone peroxide, and cyclohexanone peroxide.

[0054] Examples of the hydroperoxide used as the thermal polymerization initiator include 2,5-dimethylhexane-2,5-dihydroperoxide, diisopropylbenzene hydroperoxide, cumene hydroperoxide, t-butyl hydroperoxide, and 1,1,3,3-tetramethylbutyl hydroperoxide.

[0055] Examples of the diacyl peroxide used as the thermal polymerization initiator include acetyl peroxide, isobutyryl peroxide, benzoyl peroxide, decanoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, 2,4-dichlorobenzoyl peroxide, and lauroyl peroxide.

[0056] Examples of the dialkyl peroxide used as the thermal polymerization initiator include di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 1,3-bis(t-butylperoxyisopropyl)benzene, and 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne.

[0057] Examples of peroxyketals used as the thermal polymerization initiator include 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, 2,2-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)octane, and 4,4-bis(t-butylperoxy)valeric acid-n-butyl ester.

[0058] Examples of peroxyesters used as the thermal polymerization initiator include α-cumyl peroxyneodecanoate, t-butyl peroxyneodecanoate, t-butyl peroxypivalate, 2,2,4-trimethylpentylperoxy-2-ethylhexanoate, t-amyl peroxy-2-ethylhexanoate, t-butyl peroxy-2-ethylhexanoate, di-t-butylperoxyisophthalate, di-t-butylperoxyhexahydroterephthalate, t-butylperoxy-3,3,5-trimethylhexanoate, t-butyl peroxyacetate, t-butyl peroxybenzoate, and t-butyl peroxymaleic acid.

[0059] Examples of peroxydicarbonates used as the thermal polymerization initiator include di-3-methoxyperoxydicarbonate, di(2-ethylhexyl)peroxydicarbonate, bis(4-t-butylcyclohexyl)peroxydicarbonate, diisopropylperoxydicarbonate, di-n-propylperoxydicarbonate, di(2-ethoxyethyl)peroxydicarbonate, and diallylperoxydicarbonate.

[0060] Among these organic peroxides, diacyl peroxides are preferably used in view of the overall balance of safety, storage stability, and radical generating ability, and among these, benzoyl peroxide is more preferably used.

[0061] Examples of the azo compound used as the thermal polymerization initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 4,4'-azobis(4-cyanovaleric acid), 1,1-azobis-1-cyclohexanecarbonitrile, dimethyl-2,2'-azobis(isobutyrate), and 2,2'-azobis(2-amidinopropane) dihydrochloride.

[0062] Examples of the photopolymerization initiator include (bis)acylphosphine oxides, α-diketones, and coumarins.

[0063] Among the (bis)acylphosphine oxides used as the photopolymerization initiator, examples of the acylphosphine oxides include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,6-dimethoxybenzoyldiphenylphosphine oxide, 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, and salts thereof (sodium salt, potassium salt, ammonium salt, etc.). Examples of bisacylphosphine oxides include bis(2,6-dichlorobenzoyl)phenylphosphine oxide, bis(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine 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)phenylphosphine oxide, bis(2,5,6-trimethylbenzoyl)-2,4,4-trimethylpentylphosphine oxide, and salts thereof (sodium salts, potassium salts, ammonium salts, etc.).

[0064] Among these (bis)acylphosphine oxides, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylmethoxyphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoylphenylphosphine oxide sodium salt are preferred.

[0065] Examples of α-diketones used as the photopolymerization initiator include diacetyl, benzyl, camphorquinone, 2,3-pentadione, 2,3-octadione, 9,10-phenanthrenequinone, 4,4′-oxybenzyl, acenaphthenequinone, etc. Among these, camphorquinone is preferred.

[0066] Examples of coumarins used as the photopolymerization initiator include 3,3'-carbonylbis(7-diethylaminocoumarin), 3-(4-methoxybenzoyl)coumarin, 3-thienoylcoumarin, 3-benzoyl-5,7-dimethoxycoumarin, 3-benzoyl-7-methoxycoumarin, 3-benzoyl-6-methoxycoumarin, 3-benzoyl-8-methoxycoumarin, 3-benzoylcoumarin, 7-methoxy-3-(p-nitrobenzoyl)coumarin, 3-(p-nitrobenzoyl)coumarin, 3,5-carbonylbis(7-methoxycoumarin), coumarin), 3-benzoyl-6-bromocoumarin, 3,3'-carbonylbiscoumarin, 3-benzoyl-7-dimethylaminocoumarin, 3-benzoylbenzo[f]coumarin, 3-carboxycoumarin, 3-carboxy-7-methoxycoumarin, 3-ethoxycarbonyl-6-methoxycoumarin, 3-ethoxycarbonyl-8-methoxycoumarin, 3-acetylbenzo[f]coumarin, 3-benzoyl-6-nitrocoumarin, 3-benzoyl-7-diethylaminocoumarin, 7-dimethylamino-3-(4-methoxybenzoyl)coumarin, 7-di Ethylamino-3-(4-methoxybenzoyl)coumarin, 7-diethylamino-3-(4-diethylamino)coumarin, 7-methoxy-3(4-methoxybenzoyl)coumarin, 3-(4-nitrobenzoyl)benzo[f]coumarin, 3-(4-ethoxycinnamoyl)-7-methoxycoumarin, 3-(4-dimethylaminocinnamoyl)coumarin, 3-(4-diphenylaminocinnamoyl)coumarin, 3-[(3-dimethylbenzothiazol-2-ylidene)acetyl]coumarin, 3-[(1-methylnaphtho[1,2-d]thiazol-2-ylidene)acetyl]coumarin, -ylidene)acetyl]coumarin, 3,3'-carbonylbis(6-methoxycoumarin), 3,3'-carbonylbis(7-acetoxycoumarin), 3,3'-carbonylbis(7-dimethylaminocoumarin), 3-(2-benzothiazolyl)-7-(diethylamino)coumarin, 3-(2-benzothiazolyl)-7-(dibutylamino)coumarin, 3-(2-benzimidazolyl)-7-(diethylamino)coumarin, 3-(2-benzothiazolyl)-7-(dioctylamino)coumarin, 3-acetyl-7-(dimethylamino)coumarin, 3,Examples of compounds include those described in JP-A-9-3109 and JP-A-10-245525, such as 3'-carbonylbis(7-dibutylaminocoumarin), 3,3'-carbonyl-7-diethylaminocoumarin-7'-bis(butoxyethyl)aminocoumarin, 10-[3-[4-(dimethylamino)phenyl]-1-oxo-2-propenyl]-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5H,11H-[1]benzopyrano[6,7,8-ij]quinolizin-11-one, and 10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5H,11H-[1]benzopyrano[6,7,8-ij]quinolizin-11-one.

[0067] Among the above-mentioned coumarin compounds, 3,3'-carbonylbis(7-diethylaminocoumarin) and 3,3'-carbonylbis(7-dibutylaminocoumarin) are preferred.

[0068] Among these photopolymerization initiators, it is preferable to use at least one selected from the group consisting of (bis)acylphosphine oxides, α-diketones, and coumarins, which are widely used in dental curable compositions.

[0069] Furthermore, if necessary, the photopolymerization initiator may be further blended with a polymerization accelerator, which may allow photopolymerization to be carried out more efficiently in a shorter time.

[0070] Polymerization accelerators suitable for photopolymerization initiators include mainly tertiary amines, aldehydes, compounds having a thiol group, sulfinic acid and its salts, and the like.

[0071] Examples of tertiary amines include N,N-dimethylaniline, N,N-dimethyl-p-toluidine, N,N-dimethyl-m-toluidine, N,N-diethyl-p-toluidine, N,N-dimethyl-3,5-dimethylaniline, N,N-dimethyl-3,4-dimethylaniline, N,N-dimethyl-4-ethylaniline, N,N-dimethyl-4-isopropylaniline, N,N-dimethyl-4-t-butylaniline, and N,N-dimethyl-3,5-di-t-butylaniline. Phosphorus, N,N-bis(2-hydroxyethyl)-3,5-dimethylaniline, N,N-bis(2-hydroxyethyl)-p-toluidine, N,N-bis(2-hydroxyethyl)-3,4-dimethylaniline, N,N-bis(2-hydroxyethyl)-4-ethylaniline, N,N-bis(2-hydroxyethyl)-4-isopropylaniline, N,N-bis(2-hydroxyethyl)-4-t-butylaniline, N,N-bis(2-hydroxyethyl)-3,5-di Examples of the methyl methyl aniline include isopropylaniline, N,N-bis(2-hydroxyethyl)-3,5-di-t-butylaniline, n-butoxyethyl 4-(N,N-dimethylamino)benzoate, 2-(methacryloyloxy)ethyl 4-(N,N-dimethylamino)benzoate, ethyl 4-(N,N-dimethylamino)benzoate, n-butyl 4-(N,N-dimethylamino)benzoate, N-methyldiethanolamine, 4-(dimethylamino)benzophenone, trimethylamine, triethylamine, N-methyldiethanolamine, N-ethyldiethanolamine, Nn-butyldiethanolamine, N-lauryldiethanolamine, triethanolamine, 2-(dimethylamino)ethyl methacrylate, N-methyldiethanolamine dimethacrylate, N-ethyldiethanolamine dimethacrylate, triethanolamine monomethacrylate, triethanolamine dimethacrylate, and triethanolamine trimethacrylate.

[0072] Examples of aldehydes include dimethylaminobenzaldehyde, terephthalaldehyde, etc. Examples of compounds having a thiol group include 2-mercaptobenzoxazole, decanethiol, 3-mercaptopropyltrimethoxysilane, thiobenzoic acid, etc.

[0073] Examples of sulfinic acids and salts thereof include benzenesulfinic acid, sodium benzenesulfinate, potassium benzenesulfinate, calcium benzenesulfinate, lithium benzenesulfinate, p-toluenesulfinic acid, sodium p-toluenesulfinate, potassium p-toluenesulfinate, calcium p-toluenesulfinate, lithium p-toluenesulfinate, 2,4,6-trimethylbenzenesulfinic acid, sodium 2,4,6-trimethylbenzenesulfinate, potassium 2,4,6-trimethylbenzenesulfinate, and 2,4,6-trimethylbenzenesulfinic acid. Examples thereof include calcium benzenesulfinate, lithium 2,4,6-trimethylbenzenesulfinate, 2,4,6-triethylbenzenesulfinic acid, sodium 2,4,6-triethylbenzenesulfinate, potassium 2,4,6-triethylbenzenesulfinate, calcium 2,4,6-triethylbenzenesulfinate, 2,4,6-triisopropylbenzenesulfinic acid, sodium 2,4,6-triisopropylbenzenesulfinate, potassium 2,4,6-triisopropylbenzenesulfinate, and calcium 2,4,6-triisopropylbenzenesulfinate.

[0074] As the chemical polymerization initiator, a combination of an organic peroxide and a polymerization accelerator is preferably used. The organic peroxide used as the chemical polymerization initiator is not particularly limited, and known organic peroxides can be used. Specific examples include the organic peroxides exemplified above as the thermal polymerization initiator.

[0075] Among these organic peroxides, diacyl peroxides are preferably used in view of the overall balance of safety, storage stability, and radical generating ability, and among these, benzoyl peroxide is more preferably used.

[0076] The polymerization accelerator used in the chemical polymerization initiator can be selected from those generally used in industry, and among them, polymerization accelerators used in dental applications are preferably used. The polymerization accelerators can be used alone or in appropriate combination of two or more.

[0077] Specific examples of polymerization accelerators for chemical polymerization initiators include amines, sulfinic acids and their salts, copper compounds, and tin compounds.

[0078] Amines used as polymerization accelerators are divided into aliphatic amines and aromatic amines. Examples of aliphatic amines include primary aliphatic amines such as n-butylamine, n-hexylamine, and n-octylamine; secondary aliphatic amines such as diisopropylamine, dibutylamine, and N-methylethanolamine; and tertiary aliphatic amines such as N-methyldiethanolamine, N-ethyldiethanolamine, Nn-butyldiethanolamine, N-lauryldiethanolamine, 2-(dimethylamino)ethyl methacrylate, N-methyldiethanolamine dimethacrylate, N-ethyldiethanolamine dimethacrylate, triethanolamine monomethacrylate, triethanolamine dimethacrylate, triethanolamine trimethacrylate, triethanolamine, trimethylamine, triethylamine, and tributylamine. Among these, tertiary aliphatic amines are preferred from the viewpoint of the curability and storage stability of the composition, and N-methyldiethanolamine and triethanolamine are more preferably used.

[0079] Examples of aromatic amines include N,N-bis(2-hydroxyethyl)-3,5-dimethylaniline, N,N-bis(2-hydroxyethyl)-p-toluidine, N,N-bis(2-hydroxyethyl)-3,4-dimethylaniline, N,N-bis(2-hydroxyethyl)-4-ethylaniline, N,N-bis(2-hydroxyethyl)-4-isopropylaniline, N,N-bis(2-hydroxyethyl)-4-t-butylaniline, N,N-bis(2-hydroxyethyl)-3,5-diisopropylaniline, N,N-bis(2-hydroxyethyl)-3,5-di-t-butylaniline, N,N-dimethylaniline, N,N-dimethyl-p-toluidine, and N,N-dimethyl-m-toluidine. idine, N,N-diethyl-p-toluidine, N,N-dimethyl-3,5-dimethylaniline, N,N-dimethyl-3,4-dimethylaniline, N,N-dimethyl-4-ethylaniline, N,N-dimethyl-4-isopropylaniline, N,N-dimethyl-4-t-butylaniline, N,N-dimethyl-3,5-di-t-butylaniline, ethyl 4-(N,N-dimethylamino)benzoate, methyl 4-(N,N-dimethylamino)benzoate, n-butoxyethyl 4-(N,N-dimethylamino)benzoate, 2-(methacryloyloxy)ethyl 4-(N,N-dimethylamino)benzoate, 4-(dimethylamino)benzophenone, n-butyl 4-(N,N-dimethylamino)benzoate, and the like. Among these, at least one selected from the group consisting of N,N-bis(2-hydroxyethyl)-p-toluidine, ethyl 4-(N,N-dimethylamino)benzoate, n-butoxyethyl 4-(N,N-dimethylamino)benzoate, and 4-N,N-dimethylaminobenzophenone is preferably used, from the viewpoint of imparting excellent curability to the composition.

[0080] Examples of sulfinic acids and salts thereof used as polymerization accelerators include p-toluenesulfinic acid, sodium p-toluenesulfinate, potassium p-toluenesulfinate, lithium p-toluenesulfinate, calcium p-toluenesulfinate, benzenesulfinic acid, sodium benzenesulfinate, potassium benzenesulfinate, lithium benzenesulfinate, calcium benzenesulfinate, 2,4,6-trimethylbenzenesulfinic acid, sodium 2,4,6-trimethylbenzenesulfinate, potassium 2,4,6-trimethylbenzenesulfinate, lithium 2,4,6-trimethylbenzenesulfinate, calcium 2,4,6-trimethylbenzenesulfinate, and 2,4,6-triethylbenzenesulfinate. Examples thereof include 2,4,6-triisopropylbenzenesulfinic acid, sodium 2,4,6-triethylbenzenesulfinate, potassium 2,4,6-triethylbenzenesulfinate, lithium 2,4,6-triethylbenzenesulfinate, calcium 2,4,6-triethylbenzenesulfinate, 2,4,6-triisopropylbenzenesulfinic acid, sodium 2,4,6-triisopropylbenzenesulfinate, potassium 2,4,6-triisopropylbenzenesulfinate, lithium 2,4,6-triisopropylbenzenesulfinate, and calcium 2,4,6-triisopropylbenzenesulfinate, and sodium benzenesulfinate, sodium p-toluenesulfinate, and sodium 2,4,6-triisopropylbenzenesulfinate are preferred.

[0081] Suitable copper compounds used as polymerization accelerators include, for example, copper acetylacetonate, copper (II) acetate, copper oleate, copper (II) chloride, and copper (II) bromide.

[0082] Examples of tin compounds used as polymerization accelerators include di-n-butyltin dimaleate, di-n-octyltin dimaleate, di-n-octyltin dilaurate, di-n-butyltin dilaurate, etc. Among these, preferred tin compounds are di-n-octyltin dilaurate and di-n-butyltin dilaurate.

[0083] As the polymerization initiator, a photopolymerization initiator and a thermal polymerization initiator can be used in combination. In this case, a combination of (bis)acylphosphine oxides and diacyl peroxides is more preferred.

[0084] The content of the polymerization initiator in the polymerizable monomer-containing composition is not particularly limited, but from the viewpoint of the curability of the resulting composition, it is preferable to contain 0.001 to 30 parts by mass of the polymerization initiator per 100 parts by mass of the polymerizable monomer. When the content of the polymerization initiator is 0.001 part by mass or more, polymerization proceeds sufficiently without risk of a decrease in mechanical strength, and the content is more preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more. On the other hand, when the content of the polymerization initiator is 30 parts by mass or less, sufficient mechanical strength can be obtained even when the polymerization performance of the polymerization initiator itself is low, and furthermore, there is no risk of precipitation from the composition, and the content is more preferably 20 parts by mass or less.

[0085] In addition to the above components, the curable resin or polymerizable monomer-containing composition used in the present invention may further contain, depending on the purpose, pH adjusters, ultraviolet absorbers, antioxidants, polymerization inhibitors, colorants (inorganic pigments, composite pigments, fluorescent pigments, etc.), antibacterial agents, X-ray contrast agents, thickeners, etc. Examples of colorants include those described above as colorants contained in the unsintered zirconia molded body.

[0086] The method for infiltrating a curable resin or polymerizable monomer-containing composition into an unsintered zirconia molded body is not particularly limited, as long as the curable resin or polymerizable monomer-containing composition can penetrate into the gaps between the zirconia particles in the unsintered zirconia molded body. However, a simple and preferred method is to immerse the molded body in the curable resin or polymerizable monomer-containing composition. Immersion allows the curable resin or polymerizable monomer to gradually penetrate into the interior of the molded body (aggregate) due to capillary action. In this case, placing the surrounding environment under a reduced pressure is preferred, as this promotes the penetration of the liquid monomer. Furthermore, repeating the operation of reducing pressure and then returning to normal pressure (reduced pressure / normal pressure operation) multiple times is effective in shortening the process time for completely infiltrating the curable resin or polymerizable monomer into the molded body. The degree of reduced pressure at this time is appropriately selected taking into consideration the viscosity of the monomer or the particle size of the zirconia particles that make up the unsintered zirconia molded body, but is usually 100 hPa (10 kPa) or less, preferably 50 to 0.001 hPa (5 to 0.0001 kPa), and more preferably 20 to 0.1 hPa (2 to 0.01 kPa). -1 ~1×10 -8 Pa).

[0087] As a method other than immersion, a method of applying pressure to a molded article in a mold while the molded article is still in the mold to transfer the curable resin or polymerizable monomer-containing composition to the molded article can be considered. This method allows the subsequent curing step to be carried out continuously in the mold. The pressure conditions are preferably 2 MPa or more, more preferably 10 MPa or more, and even more preferably 20 MPa or more.

[0088] Furthermore, as a method for infiltrating a curable resin or a polymerizable monomer into the interior of an unsintered zirconia molded body without leaving any gaps, there is a method in which an unsintered zirconia composite seemingly infiltrated with the curable resin or the polymerizable monomer is placed under pressurized conditions for a certain period of time. That is, it is preferable to place the zirconia composite infiltrated with the curable resin or the polymerizable monomer together with the curable resin or the polymerizable monomer under pressurized conditions using a CIP device or the like. The pressurized conditions are preferably 20 MPa or more, more preferably 50 MPa or more, and even more preferably 100 MPa or more. Furthermore, it is even more preferable to release the pressure, return to normal pressure, and then pressurize again, repeating pressurization / normal pressure.

[0089] The viscosity of the curable resin or polymerizable monomer-containing composition also affects the rate of penetration into the unsintered zirconia molded body; typically, the lower the viscosity, the faster the penetration. The preferred viscosity range (at 25°C) is 10 Pa·s or less, more preferably 5 Pa·s or less, and even more preferably 2 Pa·s or less. However, the selection of the curable resin or polymerizable monomer must take into account factors other than viscosity, such as mechanical strength or refractive index. Alternatively, the curable resin or polymerizable monomer-containing composition may be diluted with a solvent and then subsequently distilled off under reduced pressure. The viscosity of the curable resin or polymerizable monomer-containing composition can be reduced, thereby accelerating penetration, by increasing the temperature to a range of preferably 25°C or higher, more preferably 30°C or higher, and preferably 70°C or lower, more preferably 60°C or lower.

[0090] The time for which the curable resin or polymerizable monomer-containing composition is infiltrated into the unsintered zirconia molded body is not universally determined, but can be adjusted appropriately depending on the type of zirconia, the size of the molded body, the degree of infiltration of the monomer, the contact method, etc. For example, the time for infiltration by immersion is usually 1 to 120 hours, for immersion under reduced pressure it is usually 0.5 to 12 hours, and for contact under pressure it is usually 0.2 to 6 hours.

[0091] After the step (2), in the step (3), the curable resin or polymerizable monomer is cured while the curable resin or polymerizable monomer has penetrated into the inside of the unsintered zirconia molded body.

[0092] When a curable resin is used, the curing can be softened and fluidized by heating, and cured by a crosslinking reaction, or by adding a curing accelerator. When a polymerizable monomer-containing composition is used, the curing can be carried out by thermal polymerization, photopolymerization, or chemical polymerization, and the conditions can be determined according to known methods. Among these, in the present invention, it is preferable to carry out thermal polymerization in order to increase the polymerization rate of the polymerizable monomer and obtain a dental mill blank with higher mechanical strength. The photopolymerization in the present invention can be carried out not only with visible light but also with UV light.

[0093] In step (3), curing may be performed under atmospheric pressure, a vacuum, or a pressure of 50 MPa or more. When using a polymerizable monomer-containing composition, polymerizing the pressed molded body impregnated with the polymerizable monomer under an inert atmosphere such as nitrogen gas or a reduced pressure environment can increase the polymerization rate and further enhance mechanical strength. From the standpoint of productivity, it is preferable to perform the polymerization operation by packaging the molded body impregnated with the polymerizable monomer in a vacuum pack or the like. In this case, pressurized and heated polymerization can also be performed using an autoclave or the like. Furthermore, polymerization and curing can also be performed while the unsintered zirconia molded body infiltrated with the polymerizable monomer is still under pressure. Such pressurized polymerization is one of the more preferred polymerization and curing methods in the present invention. Specifically, placing the unsintered zirconia molded body infiltrated with the polymerizable monomer under pressurized conditions together with the polymerizable monomer allows the polymerizable monomer to penetrate further into the minute gaps in the molded body and eliminates residual microscopic bubbles. Polymerization under pressurized conditions can further enhance mechanical strength. Such pressure conditions are preferably 20 MPa or higher, more preferably 50 MPa or higher, and even more preferably 100 MPa or higher. Generally, higher pressures are preferable, but in practice, the pressure depends on the capacity of the pressure device used. Examples of such pressure devices include autoclaves, CIP devices, and HIP (hot isostatic pressing) devices. For example, Kobe Steel, Ltd.'s "Dr.CHEF" CIP device, which can be pressurized to approximately 980 MPa, is known. In addition to thermal polymerization, in which polymerization is achieved by raising the temperature under pressure, photopolymerization or chemical polymerization is also possible. A more preferred pressure polymerization method is to vacuum-seal a molded product impregnated with a polymerizable monomer in a plastic bag, rubber tube, or the like, and polymerize it under pressure using a CIP device or the like. The higher the pressure, the better, preferably 50 MPa or higher, more preferably 200 MPa or higher. Furthermore, a more preferred polymerization method for enhancing mechanical strength involves sealing a molded product impregnated with a polymerizable monomer, placing it in a CIP treatment chamber, applying a predetermined pressure, and then heating the treatment chamber to initiate polymerization under high pressure.For example, after applying pressure by CIP at room temperature, the temperature is raised over a period of about 30 minutes to 24 hours, and the ultimate temperature is preferably 80 to 180°C. The polymerization time and ultimate temperature are set taking into consideration the decomposition temperature of the polymerization initiator blended with the polymerizable monomer. The polymerization temperature (ultimate temperature) may be, for example, 60 to 190°C. Furthermore, when a curable resin is used, the curing conditions can be set in the same manner as the conditions for the polymerizable monomer-containing composition.

[0094] Furthermore, by subjecting the hardened product to heat treatment preferably at 80 to 150° C. for 10 to 180 minutes, stress strain generated inside the hardened product can be alleviated, and breakage during cutting of the dental prosthesis can be suppressed.

[0095] When the resin constituting the green zirconia composite is a thermoplastic resin, it is preferable to include a step of molten the thermoplastic resin prior to step (2). The third component that can be added to the thermoplastic resin, the method for impregnating the green zirconia composite with the third component, and the conditions for impregnation are the same as those in the case of using the polymerizable monomer described above.

[0096] As described above, the method for producing an unsintered zirconia composite of the present invention involves infiltrating a curable resin or a polymerizable monomer-containing composition into an unsintered zirconia molded body obtained by press-molding a zirconia raw material, thereby curing the curable resin or the polymerizable monomer, or infiltrating a molten thermoplastic resin into the unsintered zirconia molded body. More specifically, zirconia (preferably zirconia powder) is press-molded to prepare a bulk green zirconia molded body of appropriate size, in which the unsintered zirconia aggregates. Such a molded body is, for example, a compact in which individual zirconia particles are closely packed together. The molded body is then infiltrated with a curable resin, a polymerizable monomer-containing composition, or a molten thermoplastic resin. This allows the curable resin, the polymerizable monomer-containing composition, or the thermoplastic resin to penetrate into the gaps between the zirconia primary particles that make up the molded body. By curing in this state, an unsintered zirconia composite is obtained in which the zirconia is densely packed, making it possible to obtain a high-strength dental mill blank. In this respect, the method is completely different from the conventional method of manufacturing a dental mill blank, which is formed through a firing process.

[0097] The zirconia content in the unsintered zirconia composite of the present invention varies depending on the particle size or shape of the zirconia powder used, but even when a zirconia powder with a small particle size is used, it is usually 60% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 82% by mass or more, particularly preferably 85% by mass or more, and preferably 96% by mass or less, more preferably 95% by mass or less. That is, the zirconia content in the unsintered zirconia composite of the present invention is preferably 60 to 96% by mass, more preferably 70 to 96% by mass, even more preferably 80 to 95% by mass, particularly preferably 85 to 95% by mass. The zirconia content can be measured by the ignition residue of the unsintered zirconia composite (cured product).

[0098] Furthermore, when the polished, smooth surface of the unsintered zirconia composite of the present invention is observed under a microscope, it is possible to observe that the zirconia particles are packed very densely. By analyzing such a microscopic image by image processing and calculating the areas of the zirconia portion and the resin matrix portion, it is possible to indirectly estimate the zirconia content. For example, image analysis software (Image J, National Institutes of Health, USA) can be used as such an image processing system.

[0099] From the viewpoints of moldability and sinterability, the average particle size of zirconia in the green zirconia composite of the present invention is preferably 0.001 to 10 μm, more preferably 0.005 to 5 μm, and even more preferably 0.01 to 1 μm. Furthermore, the particle size range of zirconia in the green zirconia composite of the present invention is preferably 0.0005 to 50 μm, more preferably 0.0005 to 10 μm, and even more preferably 0.0005 to 5 μm. In this specification, the average particle size of zirconia refers to the particle size of the primary particles of zirconia particles (average primary particle size). Furthermore, in this specification, the particle size range refers to the particle size range satisfied by 95% or more of the number of particles in the population used for measurement. Even if particles outside the specified particle size range are unintentionally included, there are no particular limitations as long as they are within the range that does not impair the effects of the present invention. The average particle size and particle size range can be measured by laser diffraction / scattering. Specifically, the laser diffraction scattering method can be performed using a laser diffraction particle size distribution analyzer (SALD-2300, manufactured by Shimadzu Corporation) using a 0.2% aqueous solution of sodium hexametaphosphate as a dispersion medium.

[0100] From the viewpoint of machinability and machinability, the unsintered zirconia composite of the present invention preferably has a biaxial bending strength and Vickers hardness that satisfy specific ranges. Specifically, the biaxial bending strength is preferably 20 to 140 MPa, more preferably 40 to 90 MPa, and even more preferably 50 to 80 MPa from the viewpoint of superior machinability and machinability. The Vickers hardness is preferably 5 to 140 Hv, more preferably 10 to 120 Hv, and even more preferably 20 to 100 Hv. Furthermore, as a property related to the biaxial bending strength, from the viewpoint of fine part reproducibility, the breaking load is preferably 35 to 100 N, more preferably 40 to 95 N, and even more preferably 45 to 90 N. In a preferred embodiment, an unsintered zirconia composite is provided that is composed of an unsintered zirconia molded body and a resin, the unsintered zirconia molded body being infiltrated with the resin, and that has a biaxial flexural strength of 50 to 80 MPa and a Vickers hardness of 80 to 120 Hv, because the unsintered zirconia composite has physical properties such as strength that can withstand machining such as cutting without undergoing a typical calcination step and can suppress cracking or chipping during machining such as cutting. Furthermore, the unsintered zirconia composite in the preferred embodiment is particularly preferably one in which the unsintered zirconia molded body contains 2 to 8 mol% yttria. Details of the methods for measuring the biaxial flexural strength, Vickers hardness, and fracture load are described in the Examples below.

[0101] Another preferred embodiment is a dental mill blank made of the unsintered zirconia composite of the present invention. The unsintered zirconia composite of the present invention can be suitably used as a dental mill blank. The obtained dental mill blank is cut to the desired size, machined, and surface polished as needed, and then shipped as a product. The dental mill blank of the present invention has a high zirconia content in the cured product, and despite not undergoing a typical calcination process (higher than 800°C and up to 1200°C), it has a processing strength equivalent to that achieved by dental mill blanks that have undergone a conventional typical calcination process.

[0102] From the viewpoint of hydrophobicity, the surface contact angle of the unsintered zirconia composite and dental mill blank of the present invention is preferably 35° or more, more preferably 35 to 100°, and even more preferably 40 to 80°, as measured by the Young-Laplace method. By impregnating the unsintered zirconia compact with a resin, the unsintered zirconia composite and dental mill blank of the present invention can satisfy the above-mentioned range for the surface contact angle. Conventional calcined zirconia bodies or processed bodies thereof have fine pores inside, and the surface of the compact itself is made hydrophilic by the action of capillary action due to these pores. In contrast, in the present invention, the pores are blocked with a resin, and the surface of the compact or processed body is coated with a resin to make it hydrophobic. Therefore, by having this structural feature, hydrophobicity can be imparted to the surface of the sintered zirconia composite and dental mill blank, regardless of the type of impregnated resin. The surfaces of the unsintered zirconia composite and dental mill blank of the present invention are hydrophobic, and therefore are not affected by coolant even in wet processing using a coolant, and can be suitably used in wet processing. Details of the method for measuring the contact angle will be described in the Examples below.

[0103] The dental mill blank of the present invention is preferably processed to a suitable size so that it can be set in a commercially available dental CAD / CAM system. Preferred sizes include, but are not limited to, a 40 mm × 20 mm × 15 mm prism suitable for the fabrication of a single-tooth missing bridge, a 17 mm × 10 mm × 10 mm prism suitable for the fabrication of an inlay or onlay, a 14 mm × 18 mm × 20 mm prism suitable for the fabrication of a full crown, and a disk shape with a diameter of 100 mm and a thickness of 10 to 28 mm suitable for the fabrication of a long-span bridge or denture base.

[0104] By machining the dental mill blank of the present invention, an aesthetic dental prosthesis having high mechanical strength can be provided. The method for manufacturing the dental prosthesis of the present invention includes a step (I) of machining the dental mill blank of the present invention and a step (II) of sintering the green dental prosthesis. The sintering step (II) includes a step of degreasing the green dental prosthesis (burning off the resin) and a step of firing the green dental prosthesis. It is preferable to degrease the green dental prosthesis at a temperature of 800°C or less. The heating rate and holding time until the maximum temperature is reached can be appropriately adjusted so that degreasing can be performed at a temperature of 800°C or less. The degreasing step may be included in the heating step, for example, when raising the temperature from room temperature to the maximum firing temperature. Furthermore, a general dental porcelain firing furnace can be used for sintering. Commercially available dental porcelain firing furnaces may be used. Commercially available products include "Noritake Katana (registered trademark) F-1N" and "Noritake Katana (registered trademark) F-2" (both manufactured by SK Medical Electronics Co., Ltd.). The retention time in the dental porcelain firing furnace is preferably 1 to 140 minutes. The maximum sintering temperature is preferably 1400 to 1600°C.

[0105] Dental prostheses manufactured from the dental mill blank of the present invention include, for example, crown restorations such as inlays, onlays, veneers, crowns, and bridges, as well as abutments, dental posts, dentures, denture bases, implant components (fixtures, abutments), etc. The cutting process is preferably performed using, for example, a commercially available dental CAD / CAM system, examples of which include the CEREC system manufactured by Dentsply Sirona Inc. and the Katana (registered trademark) system manufactured by Kuraray Noritake Dental Co., Ltd.

[0106] Furthermore, the mill blank obtained by the present invention can be used for purposes other than dental applications, such as electronic materials applications such as sealing materials and laminate molding materials, and general-purpose composite material components, such as parts for construction, electrical appliances, household goods, and toys. [Example]

[0107] EXAMPLES The present invention will be specifically explained below by showing examples and comparative examples, but the present invention is not limited to the following examples.

[0108] [Production Example 1: Zirconia powder] The zirconia powder used in the examples and comparative examples described below was prepared as follows. A mixture was prepared using zirconia powder and yttria powder so that the yttria content was 6 mol %. Next, this mixture was added to water to prepare a slurry, which was then wet-pulverized and mixed in a ball mill until the average particle size reached 0.13 μm (particle size range: 0.110 μm to 0.133 μm). The pulverized slurry was dried in a spray dryer, and the resulting powder was fired at 950°C for 2 hours to prepare a primary powder. Water was then added to the resulting powder to prepare a slurry, which was then wet-pulverized and mixed in a ball mill until the average particle size reached 0.13 μm. The pulverized slurry was dried in a spray dryer to obtain a secondary powder, which was used to prepare the zirconia powder (hereinafter, sometimes referred to as "6 mol % yttria-containing zirconia powder"). The average particle size and particle size range can be measured using a laser diffraction particle size distribution analyzer (SALD-2300, manufactured by Shimadzu Corporation) using a 0.2% aqueous solution of sodium hexametaphosphate as a dispersion medium.

[0109] [Polymerizable monomer, thermal polymerization initiator, antioxidant, photopolymerization initiator] In the examples and comparative examples described below, the following polymerizable monomers, thermal polymerization initiators, antioxidants, and photopolymerization initiators were used. Polymerizable monomer: 2,2,4-Trimethylhexamethylenebis(2-carbamoyloxyethyl)dimethacrylate (UDMA) ("HTM" manufactured by Kyoeisha Chemical Co., Ltd.) 2-Hydroxyethyl methacrylate (HEMA) (Nippon Shokubai Co., Ltd.) Triethylene glycol dimethacrylate (3G) ("NK Ester 3G" manufactured by Shin-Nakamura Chemical Co., Ltd.) Polyethylene glycol #600 dimethacrylate (14G) ("NK Ester Polyethylene Glycol Methacrylate 14G" manufactured by Shin-Nakamura Chemical Co., Ltd.) Thermal polymerization initiator: Benzoyl peroxide (75% purity, diluted with water) (BPO) ("Niper (registered trademark) BW" manufactured by Nippon Oil & Fats Co., Ltd.) Antioxidants: 3,5-Di-t-butyl-4-hydroxytoluene (BHT) (Fujifilm Wako Pure Chemical Industries, Ltd.) Photoinitiator: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO) ("Omnirad TPO H" manufactured by IGM Resins BV)

[0110] [Production of green zirconia compacts, green zirconia composites, and dental prostheses] Example 1 25.5 g of the 6 mol% yttria-containing zirconia powder obtained in Production Example 1 was filled into a mold with inner dimensions of 35 mm x 25 mm. The powder was leveled by tapping, and then uniaxially pressed at a pressure of 68.6 MPa for 3 minutes to obtain a plate-shaped unsintered zirconia molded body measuring 35 mm x 25 mm x 14 mm. Next, a total of 30 g of polymerizable monomer, thermal polymerization initiator, antioxidant, and photopolymerization initiator were placed in a beaker and mixed using a stirrer to produce a polymerizable monomer-containing composition, as shown in Table 1. The unsintered zirconia molded body was then immersed in 15 g of the polymerizable monomer-containing composition and allowed to stand in a dark place at room temperature for 24 hours. The polymerizable monomer-containing composition adhering to the outside of the molded body was then wiped off to obtain a molded body permeated with the polymerizable monomer-containing composition. The resulting green compact was then heat-treated in a hot air dryer at atmospheric pressure at 80°C for 120 minutes and then at 110°C for 20 minutes to obtain the desired green zirconia composite. The green zirconia composite was then dry-cut using a commercially available CAD / CAM system, "CEREC MC XL" (manufactured by Dentsply Sirona Inc.). The absence of cracking or chipping was visually confirmed, and a maxillary first molar crown was successfully fabricated. The resulting crown was then sintered using a "Noritake Katana® F-1N" (SK Medical Electronics Co., Ltd.) at a maximum temperature of 1550°C for 90 minutes, resulting in a dental prosthesis.

[0111] Examples 2 to 4 By manufacturing in the same manner as in Example 1 except that the polymerizable monomer-containing composition was changed to the composition shown in Table 1, an unsintered zirconia composite and a dental prosthesis free from cracking and chipping could be obtained.

[0112] Example 5 An unsintered zirconia composite and a dental prosthesis free from cracking and chipping were obtained by manufacturing in the same manner as in Example 1, except that after uniaxial pressing, CIP treatment was performed under conditions of 170 MPa and a holding time of 1 minute to obtain an unsintered zirconia molded body.

[0113] (Comparative Example 1) An unsintered zirconia molded body was prepared in the same manner as in Example 5, but was not impregnated with a polymerizable monomer-containing composition. A maxillary first molar crown was then produced using the commercially available CAD / CAM system "CEREC MC XL" (manufactured by Dentsply Sirona Co., Ltd.). During processing, the unsintered zirconia molded body cracked inside the device when it came into contact with the processing tool, and a dental prosthesis could not be obtained.

[0114] [Preparation of specimens for biaxial bending strength, breaking load, contact angle, and Vickers hardness measurements] 2 g of zirconia powder containing 6 mol % yttria was filled into a cylindrical mold having an inner diameter of 19 mm, and for Examples 1 to 5, the same method as for producing the unsintered zirconia composite described above was used, and for Comparative Example 1, the same method as for producing the unsintered zirconia molded body described above was used to obtain a sample having a diameter of 19 mm and a thickness of 2 mm.

[0115] [Measurement of biaxial bending strength and breaking load] The biaxial bending strength and breaking load (the load required to break the sample) of the sample were measured (n=3) using a universal testing machine (manufactured by Instron) at a crosshead speed of 0.5 mm / min in accordance with ISO 6872:2015. The average values ​​of the measured values ​​are shown in Table 1.

[0116] [Contact angle measurement] To confirm the hydrophobicity, ion-exchanged water was extruded as droplets of 0.2 to 0.3 μm in size using a contact angle measurement device "FM40 Easy Drop" (manufactured by KRUSS), brought into contact with the sample, and then the droplets were placed on the surface of the sample, and the contact angles were measured using the Young-Laplace method (n=3). The average values ​​of the measured values ​​are shown in Table 1.

[0117] [Vickers hardness measurement] To confirm the surface hardness, a surface hardness tester "DVK-1" (manufactured by Matsuzawa Seiki Seisakusho (now Matsuzawa Corporation)) was used to measure the Vickers hardness (n=3) in accordance with JIS Z 2244:2009 under the conditions of a load of 5 kgf and a holding time of 15 seconds. The average values ​​of the measured values ​​are shown in Table 1.

[0118] [Table 1]

[0119] Examples 1 to 5 All of the unsintered zirconia composites of the present invention had a biaxial bending strength of 50 MPa or more and a Vickers hardness of 80 Hv or more. Furthermore, all of the unsintered zirconia composites of the present invention were able to be machined without problems, without cracking or chipping. The contact angle was 37.7° to 44.5°, and from the viewpoint of hydrophobicity, they were not affected by cooling water during machining, even in wet machining. Therefore, the unsintered zirconia composites of the present invention can be suitably used as dental mill blanks.

[0120] (Comparative Example 1) The unsintered zirconia molded body was not infiltrated with the polymerizable monomer-containing composition, and had a low biaxial bending strength of 12 MPa. The Vickers hardness could not be measured because fracture occurred when the indenter was pressed into the sample, resulting in a lack of strength and hardness suitable for cutting. The contact angle could not be measured because ion-exchanged water immediately penetrated into the sample after contact with it, resulting in the influence of cooling water during wet processing.

Claims

1. A dental mill blank comprising an unsintered zirconia composite for use in producing a zirconia sintered body, the unsintered zirconia composite comprising an unsintered zirconia molded body and a resin, the unsintered zirconia molded body being infiltrated with the resin, the unsintered zirconia molded body containing 2 to 8 mol % of yttria, and having a biaxial bending strength of 50 to 140 MPa.

2. The dental mill blank according to claim 1 , wherein the resin is a hardenable resin, a hardened product of a hardenable resin, or a polymer.

3. The dental mill blank of claim 1 , wherein the resin is a thermoplastic resin.

4. The dental mill blank according to any one of claims 1 to 3, wherein the unsintered zirconia compact contains 3 to 6 mol% yttria.

5. The dental mill blank according to any one of claims 1 to 4, wherein the unsintered zirconia molded body contains 0.0001 to 10.0 mass% of an oxide that is a colorant.

6. The dental mill blank according to any one of claims 1 to 5, wherein the average particle size of the zirconia is 0.001 to 10 µm, and the particle size range is 0.0005 to 50 µm.

7. The dental mill blank according to any one of claims 1 to 6, wherein the biaxial bending strength is 50 to 90 MPa.

8. The dental mill blank according to any one of claims 1 to 7, having a Vickers hardness of 5 to 140 Hv.

9. A dental mill blank described in any one of claims 1 to 8, wherein the contact angle of the surface is 35° or more.

10. A step (1) of press-molding zirconia to obtain an unsintered zirconia molded body; and (2) a step of infiltrating the obtained unsintered zirconia molded body with a thermoplastic resin, a curable resin, a polymerizable monomer, or a composition containing a polymerizable monomer.

11. 11. The method for producing a dental mill blank according to claim 10, further comprising, after step (2), a step (3) of curing the curable resin or the polymerizable monomer, when the unsintered zirconia molded body is infiltrated with the curable resin, the polymerizable monomer, or the composition containing the polymerizable monomer in step (2).

12. The method for manufacturing a dental mill blank according to claim 11, wherein the hardening is carried out in a vacuum state in the step (3).

13. The method for producing a dental mill blank according to claim 11, wherein in the step (3), the hardening is carried out under atmospheric pressure.

14. The method for producing a dental mill blank according to claim 11, wherein in the step (3), the hardening is carried out under a pressure of 20 MPa or more.

15. The method for producing a dental mill blank according to any one of claims 10 to 14, further comprising, together with the polymerizable monomer, a thermal polymerization initiator, a photopolymerization initiator and / or a chemical polymerization initiator.

16. The method for manufacturing a dental mill blank according to any one of claims 11 to 15, wherein the curing in the step (3) is thermal polymerization.

17. 11. The method for producing a dental mill blank according to claim 10, further comprising a step of molten the thermoplastic resin prior to step (2) when the thermoplastic resin is infiltrated into the unsintered zirconia molded body in step (2).

18. The method for manufacturing a dental mill blank according to any one of claims 10 to 17, wherein the press molding includes a uniaxial press molding process and / or a cold isostatic pressing (CIP) process.

19. A method for manufacturing a dental prosthesis, comprising the step (I) of processing a dental mill blank described in any one of claims 1 to 9, and the step (II) of sintering an unfired dental prosthesis.

20. 20. The method for producing a dental prosthesis according to claim 19, wherein in step (II), the green dental prosthesis is degreased at a temperature of 800°C or less.

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