Method for manufacturing dental prostheses

Abstract

The present invention provides a method for manufacturing a dental prosthesis in which fusing defects of porcelain are suppressed by using a zirconia composite sintered body comprising Nb2O5 and / or Ta2O5. The present invention relates to a method for manufacturing a dental prosthesis comprising a process of performing heat treatment or polishing treatment as a pretreatment on a zirconia composite sintered body comprising Nb2O5 and / or Ta2O5, and a process of building up porcelain on the zirconia composite sintered body that has undergone the pretreatment and firing it.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing a dental prosthesis. More specifically, the present invention relates to a method for manufacturing a dental prosthesis in which fusing defects of porcelain are suppressed by using a zirconia composite sintered body comprising Nb2O5 or Ta2O5. Background Technology

[0002] Conventionally, metal was frequently used for dental products (e.g., crowns, prosthetics such as crowns, crowns, and post crowns). However, metal had the drawback of lacking aesthetic appeal, and there were also cases where allergies were triggered by the leaching of the metal.

[0003] Therefore, to resolve the problems associated with the use of metals, ceramic materials such as aluminum oxide (alumina) or zirconium oxide (zirconia) have been used in dental products instead of metals. In particular, zirconia sintered bodies offer excellent aesthetics and strength, and demand is rising, especially coupled with recent price reductions.

[0004] To enhance the aesthetics of the oral cavity, it is necessary to make the appearance of dental products similar to that of natural teeth.

[0005] However, it is sometimes difficult to reproduce the same appearance as natural teeth, particularly transparency, gloss (gloss), and color tone, using the zirconia sintered body itself.

[0006] Therefore, a cladding tube is used to reproduce the same appearance as a natural tooth by fusing a ceramic material called porcelain (e.g., Patent Document 1) onto the exposed surface of a frame (substrate) formed of a zirconia sintered body, rather than exposing the zirconia sintered body. Such a dental product is referred to as a porcelain-fused zirconia tube (PFZ: Porcelain Fused to Zirconia).

[0007] As shown in Patent Document 1, it was known that when a porcelain is built on a zirconia sintered body, sandblasting treatment is performed on the zirconia sintered body to form irregularities on the surface and increase wettability, thereby building up the porcelain so that the porcelain is distributed more uniformly on the substrate and fusing becomes easier.

[0008] In addition, a method was also known in which, when building up the porcelain, the zirconia sintered body serving as the base material was not treated at all, and the porcelain was built directly onto the base material.

[0009] In addition, zirconia sintered bodies have high hardness once they are completely sintered, so they can hardly be processed with dental processing machines. For example, if a cubic zirconia sintered body is machined to obtain a zirconia sintered body with a shape that fits the patient's tooth, the consumption of metal processing tools becomes very high, and even when manufacturing just one dental prosthesis, a vast amount of time is required.

[0010] Under these circumstances, when a zirconia sintered body is used as a dental material, it is typically not a fully sintered body, but rather a plastic body in a semi-sintered state that is easy to process is processed into the shape of a desired dental prosthesis and then further sintered to produce a sintered body processed into the shape of the intended dental prosthesis. Subsequently, a small amount of adjustment processing is performed on the sintered body so that it fits without discomfort when the sintered body with the shape of a dental prosthesis is fitted into a patient's oral cavity at a dental clinic.

[0011] For this reason, it is common for outpatient visits to dental clinics to require a treatment period of more than one month from the start of treatment to the completion of treatment.

[0012] If extensive machining can be performed on the zirconia sintered body, the treatment period from the start of treatment to the completion of treatment can be significantly shortened.

[0013] In this regard, a zirconia sintered body has been proposed that has excellent machinability in the sintered state and can be processed from a prismatic or disc-shaped mill blank into the shape of a desired dental prosthesis (e.g., Patent Document 2, etc.).

[0014] Patent Document 2 discloses a processable zirconia and a method for manufacturing the same, which is a sintered body formed to include a tetragonal zirconia composite powder comprising 79.8 to 92 mol% ZrO2 and 4.5 to 10.2 mol% Y2O3 and 3.5 to 7.5 mol% Nb2O5 or 5.5 to 10.0 mol% Ta2O5, and a TiO2 nanopowder having a mass ratio of greater than 0 mass% and less than or equal to 2.5 mass% relative to the zirconia composite powder. Prior art literature

[0015] Japanese Published Patent Application No. 2017-122064 Japanese Published Patent Application No. 2015-127294 The problem to be solved

[0016] However, the inventors have newly discovered a problem in which, for a zirconia sintered body having the composition disclosed in Patent Document 2, sandblasting treatment as in Patent Document 1 is performed and a porcelain is built using the zirconia sintered body as a base, or in which no treatment is performed on the zirconia sintered body and a porcelain is built using the zirconia sintered body as a base. In particular, the above problem was discovered more significantly when performing the so-called "glaze firing," which involves building a thin layer of porcelain on a base (including coating or spraying a spray-type porcelain) and firing it as a finishing process for manufacturing a prosthesis.

[0017] The present invention aims to provide a method for manufacturing a dental prosthesis in which fusing defects of the porcelain are suppressed by using a zirconia composite sintered body comprising Nb2O5 and / or Ta2O5. means of solving the problem

[0018] The inventors, having conducted extensive research to solve the above problem, discovered that the problem can be solved by performing heat treatment or polishing treatment on a zirconia composite sintered body containing Nb2O5 and / or Ta2O5. Based on this finding, they further conducted research and completed the present invention.

[0019] That is, the present invention includes the following inventions.

[0020] [1] A process of performing heat treatment or polishing treatment as a pretreatment on a zirconia composite sintered body containing Nb2O5 and / or Ta2O5, and

[0021] A method for manufacturing a dental prosthesis comprising the process of building up a porcelain layer on a zirconia composite sintered body that has undergone the above-mentioned pretreatment and firing it.

[0022] [2] A method for manufacturing a dental prosthesis as described in [1], wherein the temperature of the heat treatment is 150 ℃ or higher and 1550 ℃ or lower.

[0023] [3] A method for manufacturing a dental prosthesis as described in [1], wherein the surface roughness Ra of the zirconia composite sintered body after the polishing treatment is 8.0 μm or less.

[0024] [4] The above zirconia composite sintered body comprises zirconia and a stabilizer capable of suppressing the phase transition of zirconia, and

[0025] In a total of 100 mol% of zirconia, the above stabilizer, Nb2O5, and Ta2O5,

[0026] The zirconia content is 78 to 97.5 mol%, and

[0027] The content of the above stabilizer is 1 to 12 mol%, and

[0028] A method for manufacturing a dental prosthesis as described in [1] or [2], wherein the content of Nb2O5 and / or Ta2O5 is 1 to 9 mol%.

[0029] [5] A method for manufacturing a dental prosthesis as described in [4], wherein the above zirconia composite sintered body further comprises an element or ion derived from a capping agent.

[0030] [6] A method for manufacturing a dental prosthesis as described in [5], wherein the content of the element or ion derived from the capping agent is greater than 0 mol% and less than or equal to 5 mol% with respect to the total of 100 mol% of zirconia, the stabilizer, Nb2O5, and Ta2O5.

[0031] [7] A method for manufacturing a dental prosthesis as described in [5] or [6], wherein the element or ion derived from the capping agent is an element or ion belonging to the 2nd to 7th periods of the periodic table, and the first ionization energy is smaller than that of a group 18 element of the same period, and / or an element or ion having a high electron affinity.

[0032] [8] A method for manufacturing a dental prosthesis as described in [5] or [6], wherein the element or ion derived from the above capping agent comprises at least one element or ion selected from the group consisting of Cu, Ag, Li, Na, K, Rb, Cs, Fr, At, I, Br, Cl, and F.

[0033] [9] A method for manufacturing a dental prosthesis as described in [5] or [6], wherein the element or ion derived from the above capping agent comprises at least one element or ion selected from the group consisting of Li, Na, K, Rb, Cs, and Fr.

[0034]

[10] A method for manufacturing a dental prosthesis as described in any one of [4] to [9], wherein the content of the above-mentioned stabilizer is A mol% and the total content of Nb2O5 and Ta2O5 is B mol%, and the ratio of A / B is 0.9 or more and 3 or less.

[0035]

[11] A method for manufacturing a dental prosthesis as described in any one of [4] to

[10] , wherein the above-mentioned stabilizer comprises Y2O3 and / or CeO2.

[0036]

[12] A method for manufacturing a dental prosthesis described in any one of [4] to

[11] , wherein the zirconia reinforcing agent is additionally included, and the content of the zirconia reinforcing agent is greater than 0 mass% and less than or equal to 6.0 mass% with respect to the total of 100 mass% of zirconia, the stabilizer, Nb2O5 and Ta2O5.

[0037]

[13] A method for manufacturing a dental prosthesis as described in

[12] , wherein the zirconia reinforcing agent comprises TiO2 and / or Al2O3.

[0038]

[14] A method for manufacturing a dental prosthesis as described in

[13] , wherein the zirconia reinforcing agent comprises TiO2 and the TiO2 content is 0.6 to 4.5 mass%.

[0039]

[15] A method for manufacturing a dental prosthesis described in any one of [1] to

[14] , wherein the average crystal grain size of the zirconia composite sintered body is 0.5 to 5.0 μm. Effects of the invention

[0040] According to the present invention, a method for manufacturing a dental prosthesis in which fusing defects of porcelain are suppressed can be provided by using a zirconia composite sintered body comprising Nb2O5 and / or Ta2O5. Brief explanation of the drawing

[0041] Figure 1 is a photograph illustrating the frontal and occlusal views of anterior teeth, premolars, and molars. Figure 2 is a photograph showing the evaluation results of the glaze firing of a dental prosthesis obtained by Example 1 of the present invention. Figure 3 is a photograph showing the evaluation results of the glaze firing of a dental prosthesis obtained by Comparative Example 1 of the present invention. Specific details for implementing the invention

[0042] The method for manufacturing a dental prosthesis according to the present invention comprises a process of performing heat treatment or polishing treatment as a pretreatment on a zirconia composite sintered body comprising Nb2O5 and / or Ta2O5, and

[0043] The process includes building up a ceramic layer on the zirconia composite sintered body that has undergone the above-mentioned pretreatment and firing it.

[0044] In this specification, the term "molded body" means that it has not reached a semi-sintered state (plastic state) or a sintered state. That is, a molded body is distinguished from plastic bodies and sintered bodies in that it remains non-plastic after being formed into a molded body by molding.

[0045] In this specification, "zirconia composite plastic" means a semi-sintered state in which raw material powder such as zirconia is necked (fixed) and the raw material powder such as zirconia is not completely sintered.

[0046] In this specification, "zirconia composite sintered body" means a sintered state in which raw material powders such as zirconia are completely sintered. In the zirconia composite sintered body, solidification or solid solution of raw material powders such as zirconia proceeds through sintering, and as the relative density increases and densification proceeds along with sintering, it is a completely sintered state with a relative density of 95% or more.

[0047] In this specification, "zirconia" refers to zirconium (IV) oxide (ZrO2) and contains a trace amount (0.5 mass% or more and 3 mass% or less) of HfO2 relative to the amount of ZrO2. Since HfO2 is difficult to separate, terms such as "zirconia" and "zirconia powder" refer to the inclusion of ZrO2 and HfO2. Additionally, powder in which a stabilizer is dissolved in zirconia is also included in "zirconia powder."

[0048] In this specification, "atmosphere" means under standard atmospheric pressure (1 atm).

[0049] In this specification, "zirconia reinforcing agent" refers to a component having the function of improving the mechanical strength of a zirconia composite sintered body.

[0050] In this specification, "building" means stacking ceramic material on a substrate using a brush or the like, and includes applying ceramic material to the substrate or spraying spray-type ceramic material onto the substrate.

[0051] In addition, the content ratio (mass%) of the zirconia reinforcing agent is the external addition rate relative to the total of 100 mass% of zirconia, the stabilizer, Nb2O5, and Ta2O5. Therefore, the content ratio of the zirconia reinforcing agent in the zirconia composite sintered body can be calculated from the amount (mass) of raw materials added when adding.

[0052] In the present specification, the content of each component in the zirconia composite sintered body can be calculated from the input amount of raw materials.

[0053] In this specification, machining includes cutting and grinding. In addition, machining may be either wet machining or dry machining and is not particularly limited.

[0054] In this specification, "surface roughness Ra" means the arithmetic mean roughness in JIS B 0601:2013.

[0055] In addition, in this specification, the upper and lower limits of the numerical range (temperature range, content of each component, existence of crystal systems, values ​​calculated from components, etc., and each physical property, etc.) can be appropriately combined.

[0056] Although it is not certain why the method for manufacturing a dental prosthesis of the present invention can suppress the fusing defect of the porcelain onto the zirconia composite sintered body that is the substrate, it is thought to be as follows.

[0057] It is thought that this is because the zirconia composite sintered body, which is the base material, contains Nb2O5 and / or Ta2O5, and unlike zirconia sintered bodies obtained by mechanically processing conventional plastics, the condition of the surface of the zirconia composite sintered body after processing is modified by heat treatment or polishing, and a state in which the porcelain is easily fused (high chemical affinity between the surface of the base material and the porcelain) can be expressed.

[0058] More specifically, as an example, in the case of a substrate containing Nb2O5 and / or Ta2O5, it can be inferred that the hydrophilic groups on the surface of the substrate generated by wet processing are dehydrated and hydrophobicized by heat treatment or polishing treatment, which contributes to the improvement of fusing defects in the ceramic.

[0059] In the method for manufacturing a dental prosthesis of the present invention, the temperature of the heat treatment is preferably 150°C or higher and 1550°C or lower, in order to easily suppress fusing defects of the porcelain.

[0060] Compared to anterior teeth, which have many flat parts and simple shapes, premolars have many curved surfaces and complex shapes such as pits and grooves visible in the occlusal surface, making it more difficult to suppress porcelain fusing defects.

[0061] Also, as shown in Fig. 1, in molars, in addition to having many curved surfaces as in premolars, the fossae and grooves observed in the occlusal surface have more complex shapes than those of premolars, and as the number of cusp tips increases, the shape becomes more complex with a greater difference in height between the fossae, grooves and cusp tips, making it more difficult to suppress the fusing defect of the porcelain.

[0062] The temperature of the heat treatment is more preferably 180°C or higher, more preferably 200°C or higher, and particularly preferably 250°C or higher, in that it is easier to suppress fusing defects of the porcelain regardless of the shape of the dental prosthesis, even if the dental prosthesis has complex shapes such as many curved surfaces and many grooves in the occlusal surface.

[0063] In addition, the temperature of the heat treatment is more preferably 1500°C or lower, more preferably 1450°C or lower, and particularly preferably 1400°C or lower, in that it is easier to suppress fusing defects of the porcelain regardless of the shape of the dental prosthesis, even if the dental prosthesis has complex shapes such as many curved surfaces and many grooves in the occlusal surface.

[0064] In the method for manufacturing a dental prosthesis of the present invention, the heat treatment time is preferably 10 seconds or more, more preferably 30 seconds or more, in order to easily suppress fusing defects of the porcelain, and is even more preferably 50 seconds or more, and particularly preferably 1 minute or more, in order to easily suppress fusing defects of the porcelain regardless of the shape of the dental prosthesis, even if the dental prosthesis has complex shapes such as many curved surfaces and many grooves in the occlusal surface.

[0065] In addition, the upper limit of the heat treatment time is not particularly limited as long as it exhibits the effects of the present invention, but in terms of time constraints when actually performing work in a clinical setting, it is preferable that it be 120 minutes or less, more preferable that it be 60 minutes or less, even more preferable that it be 30 minutes or less, and particularly preferable that it be 10 minutes or less.

[0066] As for the heating device used for heat treatment, any known heating device (e.g., a kiln) can be used, provided that it can be adjusted to the temperature range and heat treatment time mentioned above. Additionally, the heat treatment may be performed under vacuum conditions. By using a vacuum, it is possible to set the temperature of the heat treatment to a lower temperature.

[0067] In the polishing treatment, the surface roughness Ra of the zirconia composite sintered body after polishing treatment is preferably 8.0 μm or less in terms of being easy to suppress fusing defects of the porcelain, more preferably 7.5 μm or less in terms of being easy to suppress fusing defects of the porcelain regardless of the shape of the dental prosthesis, even if the dental prosthesis has complex shapes such as many curved surfaces and many grooves in the occlusal surface, more preferably 5.0 μm or less, and particularly preferably 2.0 μm or less.

[0068] Also, the lower limit of the surface roughness Ra is not specifically limited, but may be 0.001 μm or more.

[0069] In the method for manufacturing a dental prosthesis according to the present invention, unlike the method of roughening the surface by sandblasting as in the prior art, the fusing defect of the porcelain can be suppressed by polishing the surface roughness Ra within the above-mentioned range.

[0070] The polishing device and tool used for the polishing treatment are not particularly limited as long as they can be adjusted to the range of surface roughness Ra mentioned above, and known polishing devices and tools may be used.

[0071] In the method for manufacturing a dental prosthesis of the present invention, the shape of the zirconia composite sintered body is preferably a machined shape formed by building up and firing the porcelain so that it can be used as a dental prosthesis.

[0072] In addition, in the method for manufacturing a dental prosthesis of the present invention, it is preferable to perform the heat treatment or polishing treatment as a pretreatment immediately before building up the porcelain. In other words, even if the dental prosthesis has complex shapes such as many curved surfaces or many grooves in the occlusal surface, it is preferable not to perform additional treatment after the heat treatment or polishing treatment to build up the porcelain, as it is easy to suppress fusing defects of the porcelain regardless of the shape of the dental prosthesis.

[0073] When heat treatment or polishing treatment is performed at such a timing, even if irregularities are formed on the surface of the zirconia composite sintered body by first performing sandblasting treatment, the fusing defect of the porcelain can be suppressed by additionally performing heat treatment or polishing treatment. Therefore, the method for manufacturing a dental prosthesis of the present invention may additionally include sandblasting treatment before heat treatment or polishing treatment.

[0074] One preferred embodiment may include a method for manufacturing a dental prosthesis, wherein the pretreatment is heat treatment or polishing treatment, before (preferably immediately) building up a porcelain on a zirconia composite sintered body containing Nb2O5 and / or Ta2O5.

[0075] In the method for manufacturing a dental prosthesis of the present invention, the thickness of the porcelain being formed is not particularly limited as long as it exhibits the effects of the present invention, but for example, when performing glaze firing, the thickness of the porcelain after sintering may be 200 μm or less, 100 μm or less, or 50 μm or less.

[0076] By using a porcelain thickness within the above range, a dental prosthesis with superior aesthetics is obtained due to the characteristics of the porcelain.

[0077] The zirconia composite sintered body used in the method for manufacturing a dental prosthesis of the present invention comprises Nb2O5 and / or Ta2O5.

[0078] As the zirconia composite sintered body used in the method for manufacturing a dental prosthesis of the present invention, processable zirconia described in Patent Document 2 may be used.

[0079] Specifically, the zirconia composite sintered body may include a tetragonal composite zirconia comprising 79.8 to 92 mol% of ZrO2 and 4.5 to 10.2 mol% of Y2O3, 3.5 to 7.5 mol% of Nb2O5 or 5.5 to 10.0 mol% of Ta2O5, and a sintered body formed to include TiO2 with a mass ratio to the composite zirconia of greater than 0 mass% and less than or equal to 2.5 mass%.

[0080] In the zirconia composite sintered body of the present invention, the zirconia content is preferably 78 to 97.5 mol% in the total of 100 mol% of zirconia, the stabilizer, Nb2O5, and Ta2O5, more preferably 79 mol% or more and 96 mol% or less in terms of better light transmittance and strength, even more preferably 80 mol% or more and 94 mol% or less, and particularly preferably 81 mol% or more and 93 mol% or less.

[0081] Stabilizers capable of inhibiting the phase transition of zirconia include, for example, calcium oxide (CaO), magnesium oxide (MgO), yttrium oxide (Y2O3), cerium oxide (CeO2), scandium oxide (Sc2O3), lanthanum oxide (La2O3), erbium oxide (Er2O3), praseodymium oxide (Pr2O3, Pr6O3). 11 Examples of oxides include samarium oxide (Sm2O3), europium oxide (Eu2O3) and thulium oxide (Tm2O3), gallium oxide (Ga2O3), indium oxide (In2O3) and ytterbium oxide (Yb2O3), etc., and Y2O3 (yttria) and / or CeO2 are preferred in that they provide superior effects of the present invention and particularly excellent aesthetics. The above stabilizer may be used alone or in combination of two or more types.

[0082] In the zirconia composite sintered body of the present invention, the content of the stabilizer is preferably 1 to 12 mol% in the total of 100 mol% of zirconia, the stabilizer, Nb2O5, and Ta2O5, more preferably 2 mol% or more and 10 mol% or less in terms of being able to obtain sufficient machinability, more preferably 3 mol% or more and 8.0 mol% or less in terms of having better transparency and strength, more preferably 3.5 mol% or more and 7.5 mol% or less, particularly preferably 3.8 mol% or more and 7.0 mol% or less, and most preferably 4.0 mol% or more and 6.5 mol% or less.

[0083] In one preferred embodiment, a zirconia composite sintered body may be provided, wherein a stabilizer capable of suppressing phase transition of zirconia comprises Y2O3 and / or CeO2, and the total content of Y2O3 and CeO2 is 2 mol% or more and 10 mol% or less.

[0084] In another preferred embodiment, a zirconia composite sintered body may be provided, wherein the stabilizer capable of suppressing the phase transition of zirconia comprises Y2O3, and the content of Y2O3 is 2 mol% or more and 10 mol% or less.

[0085] In any of the above embodiments, the content of Y2O3 and CeO2 may be appropriately changed as long as it is within the range described in this specification, for example, the total content of Y2O3 and CeO2 may be 2.5 mol% or more and 10 mol% or less, and 3 mol% or more and 9 mol% or less in terms of better light transmittance and strength.

[0086] In addition, although it is not certain why the zirconia composite sintered body of the present invention maintains strength while having excellent machinability in the sintered state, it is presumed that this is achieved by improving fracture toughness (IF method) by adding at least one of Nb2O5 or Ta2O5 to zirconia with a conventional stabilizer, and by minimizing hardness through the coarsening of the microstructure.

[0087] In addition, in the zirconia composite sintered body of the present invention, the content of Nb2O5 or Ta2O5 is 1 to 9 mol% in the total of 100 mol% of zirconia, the stabilizer, Nb2O5, and Ta2O5, and is preferably 1.5 mol% or more and 8.5 mol% or less. It is more preferable to have 2.5 mol% or more and 8 mol% or less in terms of having superior machinability, and even more preferable to have 3 mol% or more and 7 mol% or less. If the content of Nb2O5 or Ta2O5 is less than 1 mol%, it is difficult to obtain sufficient machinability. Also, if the content of Nb2O5 or Ta2O5 exceeds 9 mol%, defects such as defects occur in the obtained zirconia composite sintered body, making it difficult to obtain sufficient physical properties.

[0088] In addition, in one preferred embodiment, in terms of superior machinability, it is preferable that the total content of Nb2O5 and Ta2O5 in the zirconia composite sintered body of the present invention be within the range of each content (1 mol% or more and 9 mol% or less, etc.).

[0089] In addition to Nb2O5 and Ta2O5 acting in a direction that reduces hardness by coarsening the microstructure as described above and acting in conjunction with capping elements or ions to provide excellent machinability, the sintering density can be maximized through interaction with other components (e.g., TiO2, Al2O3) added to the zirconia composite sintered body and the application of HIP, thereby ensuring the aesthetics of natural teeth in the dental prostheses obtained.

[0090] The content ratio of each component of the above-mentioned zirconia, stabilizer, Nb2O5, and Ta2O5 is a ratio relative to 100 mol% of the total of zirconia, stabilizer, Nb2O5, and Ta2O5, and the total of zirconia, stabilizer, Nb2O5, and Ta2O5 does not exceed 100 mol%. For example, if the raw material composition contains Nb2O5 and does not contain Ta2O5, the content ratio of each component of zirconia, stabilizer, and Nb2O5 refers to the content ratio relative to 100 mol% of the total of zirconia, stabilizer, and Nb2O5.

[0091] In addition, when the content of the stabilizer is set to A mol% and the total content of Nb2O5 and Ta2O5 is set to B mol%, the ratio of A / B is preferably 0.9 to 3 or less in terms of machinability, more preferably 0.95 to 2 or less, and more preferably 1 to 1.6 or less in terms of the effect of the capping element or ion and Nb2O5 and / or Ta2O5 acting as a single unit is enhanced, thereby providing superior machinability and suppressing the wear of the machining tool, which can further increase the number of dental prostheses obtained by continuous machining using a single machining tool.

[0092] In addition, in one preferred embodiment, the zirconia composite sintered body comprises zirconia, a stabilizer capable of suppressing the phase transition of zirconia (hereinafter also simply referred to as "stabilizer"), and Nb2O5 and / or Ta2O5, and

[0093] In a total of 100 mol% of zirconia, the above stabilizer, Nb2O5, and Ta2O5,

[0094] The zirconia content is 78 to 97.5 mol%, and

[0095] The content of the above stabilizer is 1 to 12 mol%, and

[0096] A method for manufacturing a dental prosthesis can be cited, wherein the content of Nb2O5 and / or Ta2O5 is 1 to 9 mol%.

[0097] Any of the above preferred embodiments may be a method for manufacturing a dental prosthesis that does not include elements or ions derived from the capping agent described later.

[0098] In another preferred embodiment, the zirconia composite sintered body comprises zirconia, a stabilizer, and Nb2O5 and / or Ta2O5, and

[0099] In a total of 100 mol% of zirconia, the above stabilizer, Nb2O5, and Ta2O5,

[0100] The zirconia content is 78 to 97.5 mol%, and

[0101] The content of the above stabilizer is 1 to 12 mol%, and

[0102] The content of Nb2O5 and / or Ta2O5 is 1 to 9 mol%, and

[0103] A method for manufacturing a dental prosthesis may be cited, which further comprises an element or ion derived from a capping agent.

[0104] In this specification, an element or ion derived from a capping agent (hereinafter also referred to as "capping element or ion") refers to an element or ion that caps the ends of bonding hands of a zirconia-based composite oxide in a zirconia composite sintered body composed of Nb2O5 and / or Ta2O5, thereby weakening the strength (hereinafter also referred to as "grain boundary strength") of a crystal interface (hereinafter also referred to as "grain boundary").

[0105] Capping agents can cap a portion of the crystal grain boundaries.

[0106] "Capping" refers to a phenomenon in which a target element or ion (capping element or ion) bonds with the bonding agent of a zirconia-based complex oxide in place of the metal element and exists at the crystal grain boundary.

[0107] It is presumed that capping elements or ions exist at the grain boundary in the form of +1 valence cations or -1 valence anions, causing electrostatic repulsion between the capped cations or anions, thereby weakening the grain boundary strength.

[0108] In addition, the content of each component, such as zirconia, stabilizer, Nb2O5, and Ta2O5, in the zirconia composite sintered body can be measured, for example, by inductively coupled plasma (ICP) emission spectroscopy, fluorescence X-ray analysis, etc.

[0109] The content of elements or ions derived from the capping agent (mol%) is the external addition rate relative to the total of 100 mol% of zirconia, the stabilizer, Nb2O5, and Ta2O5. Therefore, the content of elements or ions derived from the capping agent in the zirconia composite sintered body can be calculated by converting the amount of raw material input (mass) at the time of addition into mol%.

[0110] In the zirconia composite sintered body containing capping elements or ions, it is presumed that the presence of capping elements or ions at the grain boundaries lowers the grain boundary strength in the form of +1 valence cations or -1 valence anions, thereby acting in a direction that makes it easier to peel off the particles, and thus improves machinability in the sintered body state.

[0111] Capping elements or ions become +1 valence cations or -1 valence anions at the grain boundaries of the zirconia composite sintered body and bond with the bonding losses of the zirconia-based composite oxide. Through this bonding, cations and anions repel each other electrostatically, which weakens the grain boundary strength while maintaining the properties of strength and transparency as particles constituting the zirconia composite sintered body, and acts to improve machinability in the sintered body state.

[0112] For example, one can conceive of a form in which a +1 valence cation bonds to the other bonding hand of an oxygen atom bonded to a metal element (e.g., Zr, Hf, Y, Nb, or Ta) included in a zirconia-based complex oxide, instead of the metal element.

[0113] Also, OH2 in which a -1 valence anion is bonded to a metal element (e.g., Zr, Hf, Y, Nb, or Ta) included in a zirconia-based complex oxide ＋ One can think of a form that combines with.

[0114] In addition, one can conceive of a configuration in which an anion of -1 valence is included in a zirconia-based complex oxide and bonds to a cation derived from a metal element (e.g., Zr, Hf, Y, Nb, or Ta) that is bonded to another metal element.

[0115] In addition, Nb2O5 and / or Ta2O5 act in a direction that reduces hardness by coarsening the microstructure in a zirconia composite sintered body, so the capping element or ion and Nb2O5 and / or Ta2O5 act as a single unit to improve machinability. Therefore, since the capping element or ion and Nb2O5 and / or Ta2O5 act as a single unit, it is possible to further enhance excellent machinability while having the strength required for artificial teeth, so in addition to shortening the machining time, the wear of the machining tool can be suppressed, and the number of dental prostheses obtained by continuous machining using a single machining tool can be increased.

[0116] In the zirconia composite sintered body of the present invention, the capping element or ion further improves machinability and acts as a free-cutting aid as described above, and also does not significantly impair strength and transparency.

[0117] Regarding the content of capping elements or ions included in the zirconia composite sintered body used in the present invention, it is preferable to have a content of 0 mol% or more and 5 mol% or less, and it is more preferable to have a content of 0.05 mol% or more and 3 mol% or less in order to have superior machinability and to increase the number of dental prostheses that can be continuously processed with a single processing tool, it is even more preferable to have a content of 0.06 mol% or more and 2.5 mol% or less, it is particularly preferable to have a content of 0.07 mol% or more and 1.0 mol% or less, and most preferable to have a content of 0.08 mol% or more and 0.34 mol% or less.

[0118] In addition, when the capping element or ion included in the zirconia composite sintered body used in the present invention is a Group 17 element or ion, it is more preferable to have 0.2 mol% or more and 5 mol% or less, more preferable to have 0.3 mol% or more and 4 mol% or less, particularly preferable to have 0.4 mol% or more and 3.5 mol% or less, and most preferable to have 0.5 mol% or more and 3.0 mol% or less, in terms of superior machinability and the ability to increase the number of dental prostheses that can be continuously processed with a single processing tool.

[0119] As mentioned above, by having a capping element or ion present at the grain boundary, it becomes a +1 valence cation or a -1 valence anion, and can exhibit appropriate interaction between the charged site and the adsorption site at the grain boundary.

[0120] As for the capping element or ion, it is preferable to have an element or ion belonging to the 2nd to 7th periods of the periodic table, having a first ionization energy smaller than that of a Group 18 element of the same period, an element or ion with high electron affinity, nitrate ions, hypochlorite ions, chlorite ions, chlorate ions, perchlorate ions, bromate ions, permanganate ions, metaborate ions, and cyanide ions.

[0121] In one preferred embodiment, a zirconia composite sintered body may be provided in which the element or ion derived from the capping agent belongs to the 2nd to 7th periods of the periodic table, and the first ionization energy is smaller than that of a group 18 element of the same period, and / or the element or ion has a high electron affinity.

[0122] Among the elements belonging to the 2nd to 7th periods of the above periodic table, and having a first ionization energy smaller than that of the Group 18 elements of the same period, Cu, Ag, Li, Na, K, Rb, Cs, Fr, etc. are preferably cited in that +1 valence cations are easier to obtain and have better machinability.

[0123] As for elements with high electron affinity, Group 17 elements are preferred because -1 valence anions are easier to obtain and have better machinability. As for Group 17 elements, At, I, Br, Cl, and F are preferred.

[0124] The first ionization energy is the energy required to ionize an atom in a neutral state by removing one electron. The first ionization energy can be the same as the first ionization energy described in "Schreiber-Atkins Inorganic Chemistry (V) 4th Edition, Part I, Fundamentals 1. Atomic Structure." The first ionization energy can be converted to the unit "KJ / mol" from the unit "eV" of the first ionization energy described in "Schreiber-Atkins Inorganic Chemistry (V) 4th Edition, Appendix 2," using the equation 1 eV = 96.485 KJ / mol. The first ionization energy can also be determined by photoelectron yield spectroscopy (PYS).

[0125] Electron affinity (EA) is the energy released when one electron is introduced into an atom in a neutral state. Electron affinity can be measured by the difference in the energy gap from the ionization potential. Ionization potential is defined as the energy difference between the highest-energy occupied orbital of a compound molecule and the vacuum level, and its value is measured using ultraviolet photoelectron spectroscopy.

[0126] For the first ionization energy and electron affinity, you may use data accumulated in the NIST Chemistry WebBook (https: / / webbook.nist.gov / chemistry / ) (select Ionization Energy or Electron Affinity from Ion energetics properties).

[0127] Since the first ionization energy and electron affinity are sufficient if the degree to which they are prone to becoming +1 cations or -1 anions can be compared with other elements, the measurement method can appropriately utilize the above.

[0128] Specifically, capping elements include Cu, Ag, Li, Na, K, Rb, Cs, Fr, At, I, Br, Cl, and F, and Cu, Ag, Li, Na, K, Rb, Cs, Fr, I, Br, Cl, and F are preferred in that they can further improve machinability, and Li, Na, K, Rb, Cs, and Fr are more preferred.

[0129] In one preferred embodiment, a zirconia composite sintered body may be provided, wherein the element derived from the capping agent comprises at least one element selected from the group consisting of Cu, Ag, Li, Na, K, Rb, Cs, Fr, At, I, Br, Cl, and F, and the ion of said element is at least one +1 valence cation or -1 valence anion selected from the group consisting of Cu, Ag, Li, Na, K, Rb, Cs, Fr, I, Br, Cl, and F.

[0130] In another preferred embodiment, a zirconia composite sintered body may be provided, wherein the element or ion derived from the capping agent comprises at least one element or ion selected from the group consisting of Ag, Li, Na, K, Rb, Cs, Fr, At, I, Br, Cl, and F.

[0131] One type of capping element or ion may be used alone, or two or more types may be used in combination.

[0132] As described above, since the capping element or ion and Nb2O5 and / or Ta2O5 act as a single unit and do not impede the effect of the stabilizer, the stabilizer is not particularly limited and exhibits the effect of the present invention.

[0133] In a zirconia composite sintered body containing capping elements or ions, the type of stabilizer, zirconia, and the content of the stabilizer may be the same type and content as in the above-described embodiment.

[0134] In a zirconia composite sintered body containing a capping element or ion, the content of Nb2O5 or Ta2O5 is 1 to 9 mol% in the total of 100 mol% of zirconia, the stabilizer, Nb2O5, and Ta2O5, and is preferably 1.5 mol% or more and 8.5 mol% or less. It is more preferable to have 2.5 mol% or more and 8 mol% or less, and even more preferable to have 3 mol% or more and 7 mol% or less, in that it acts integrally with the capping element or ion to provide superior machinability. If the content of Nb2O5 or Ta2O5 is less than 1 mol%, it is difficult to obtain sufficient machinability. Furthermore, if the content of Nb2O5 or Ta2O5 exceeds 9 mol%, defects such as defects occur in the resulting zirconia composite sintered body, making it difficult to obtain sufficient physical properties.

[0135] In addition, in one preferred embodiment, in terms of superior machinability, it is preferable that the total content of Nb2O5 and Ta2O5 in the zirconia composite sintered body containing the capping element or ion be within the range of each content (1 mol% or more and 9 mol% or less, etc.).

[0136] In one preferred embodiment of the present invention, the invention comprises zirconia, a stabilizer capable of inhibiting the phase transition of zirconia, and Nb2O5 and / or Ta2O5.

[0137] In a total of 100 mol% of zirconia, the above stabilizer, Nb2O5, and Ta2O5,

[0138] The zirconia content is 78 to 97.5 mol%, and

[0139] The content of the above stabilizer is 1 to 12 mol%, and

[0140] The content of Nb2O5 and / or Ta2O5 is 1 to 9 mol%, and

[0141] Additionally, it includes capping elements or ions,

[0142] The above stabilizer comprises Y2O3 and / or CeO2, and

[0143] The content of the capping element or ion is greater than 0 mol% and less than or equal to 5 mol% with respect to 100 mol% of the total of zirconia, the stabilizer, Nb2O5, and Ta2O5, and

[0144] Examples of zirconia composite sintered bodies include those in which the ratio of A / B is 0.9 or higher and 3 or lower when the content of the above-mentioned stabilizer is A mol% and the total content of Nb2O5 and Ta2O5 is B mol%.

[0145] Other zirconia composite sintered bodies used in the present invention include zirconia, a stabilizer capable of suppressing the phase transition of zirconia, Nb2O5 and / or Ta2O5, and, in addition to a capping element or ion, a zirconia composite sintered body further comprising a zirconia reinforcing agent.

[0146] A zirconia reinforcing agent can improve the strength of a zirconia composite sintered body containing zirconia, a stabilizer capable of suppressing the phase transition of zirconia, and Nb2O5 and / or Ta2O5 by acting integrally with a capping element or ion.

[0147] In the case of a zirconia composite sintered body containing a zirconia reinforcing agent, as described above, the zirconia content, the type and content of the stabilizer, the content of Nb2O5 and / or Ta2O5, the type and content of the capping element or ion, and the ratio of A / B can be appropriately changed.

[0148] In a zirconia composite sintered body containing a zirconia reinforcing agent, the content of the zirconia reinforcing agent is preferably greater than 0 mass% and less than or equal to 6.0 mass% with respect to 100 mass% of the total of zirconia, a stabilizer capable of suppressing the phase transition of zirconia, Nb2O5, and Ta2O5; more preferably, it is greater than or equal to 0.01 mass% and less than or equal to 5.5 mass%, and even more preferably, greater than or equal to 0.5 mass% and less than or equal to 5.0 mass%, in that it acts as an integral when combined with a capping element or ion to provide superior strength.

[0149] Examples of zirconia reinforcing agents include TiO2 and Al2O3. The above zirconia reinforcing agents may be used as a single type or in combination of two or more types.

[0150] Other zirconia composite sintered bodies used in the present invention include zirconia composite sintered bodies in which the zirconia reinforcing agent contains TiO2 and the TiO2 content is 0.6 to 4.5 mass%.

[0151] Other zirconia composite sintered bodies used in the present invention include zirconia, a stabilizer capable of suppressing the phase transition of zirconia, and Nb2O5 and / or Ta2O5.

[0152] In a total of 100 mol% of zirconia, the above stabilizer, Nb2O5, and Ta2O5,

[0153] The zirconia content is 78 to 97.5 mol%, and

[0154] The content of the above stabilizer is 1 to 12 mol%, and

[0155] The content of Nb2O5 and / or Ta2O5 is 1 to 9 mol%, and

[0156] Additionally, it includes capping elements or ions,

[0157] The above stabilizer comprises Y2O3 and / or CeO2, and

[0158] The above zirconia reinforcing agent contains TiO2, and the TiO2 content is 0.6 to 4.5 mass%, and

[0159] The content of the capping element or ion is greater than 0 mol% and less than or equal to 5 mol% with respect to 100 mol% of the total of zirconia, the stabilizer, Nb2O5, and Ta2O5, and

[0160] Examples of zirconia composite sintered bodies include those in which the ratio of A / B is 0.9 or higher and 3 or lower when the content of the above-mentioned stabilizer is A mol% and the total content of Nb2O5 and Ta2O5 is B mol%.

[0161] The average crystal grain size of the zirconia composite sintered body used in the present invention is preferably 0.5 to 5.0 μm, more preferably 0.5 to 4.5 μm in terms of superior machinability, strength, and transparency, and even more preferably 0.7 to 4.0 μm. The method for measuring the average crystal grain size may be, for example, the following method.

[0162] First, for a pellet-shaped zirconia composite sintered body, a surface image is obtained using a scanning electron microscope (product name "VE-9800", manufactured by Keyence Co., Ltd.). After marking the grain boundaries of each crystal grain on the obtained image, the average crystal grain size is calculated by image analysis.

[0163] Image analysis software (product name "Image-Pro Plus," manufactured by Hakuto Co., Ltd.) is used to measure the average crystal grain size, binarizes the introduced SEM image, adjusts the brightness range so that grain boundaries become clear, and recognizes the particles from the field of view (area). The crystal grain size obtained with Image-Pro Plus is the average of the lengths of the line segments connecting the outlines passing through the center of gravity obtained from the outlines of the crystal grains, measured at 2-degree intervals centered on the center of gravity, and the arithmetic mean of the crystal grain sizes of all particles not caught in the image in the SEM photograph images (3 fields of view) of each example and comparative example is taken as the average crystal grain size (based on number) in the sintered body.

[0164] "Particles not caught in the top edge of the image" refers to particles excluding those whose outlines do not fully fit within the frame of the SEM image (particles whose outlines are broken at the top, bottom, left, and right boundary lines). The crystal grain size of all particles not caught in the top edge of the image can be selected in Image-Pro Plus as an option to exclude particles on all boundary lines.

[0165] The average crystal particle size can be measured by adjusting the number of particles so that, in the method described in the example, the number of particles included in one field of view of an SEM photograph is 50 or more, 100 or more, 200 or more, 600 or more (e.g., 800, 1000, etc.).

[0166] The density of the zirconia composite sintered body related to the present invention is preferably 5.5 g / cm³ or higher, more preferably 5.7 g / cm³ or higher, and even more preferably 5.9 g / cm³ or higher, in that the higher the density, the fewer internal pores there are and the harder it is to scatter light, thereby improving light transmittance and strength.

[0167] It is particularly desirable that the zirconia composite sintered body substantially does not contain voids.

[0168] The density of the composite sintered body can be calculated as (mass of the composite sintered body) / (volume of the composite sintered body).

[0169] As mentioned above, the zirconia composite sintered body used in the present invention may use the processable zirconia described in Patent Document 2, and said processable zirconia may be manufactured in accordance with the manufacturing method described in Patent Document 2.

[0170] In addition, a method for manufacturing a zirconia composite sintered body in which the zirconia composite sintered body used in the method for manufacturing a dental prosthesis of the present invention includes a capping element or an ion is described below.

[0171] A method for manufacturing a zirconia composite sintered body containing capping elements or ions is, for example,

[0172] zirconia, a stabilizer capable of inhibiting the phase transition of zirconia, and Nb2O5 and / or Ta2O5, comprising zirconia, and

[0173] In a total of 100 mol% of zirconia, the above stabilizer, Nb2O5, and Ta2O5,

[0174] The zirconia content is 78 to 97.5 mol%, and

[0175] The content of the above stabilizer is 1 to 12 mol%, and

[0176] The content of Nb2O5 and / or Ta2O5 is 1 to 9 mol%, and

[0177] A process for manufacturing a molded body using a raw material composition that additionally includes a capping agent, and

[0178] A method for manufacturing a zirconia composite sintered body may be used, comprising a process for sintering the above-mentioned molded body.

[0179] The raw material composition of the zirconia composite sintered body comprises zirconia, a stabilizer capable of suppressing the phase transition of zirconia, Nb2O5 and / or Ta2O5, and a capping agent. The raw material composition of the zirconia composite sintered body may be in a dry state, a state containing liquid, or a state contained in liquid. The raw material composition may be in the form of, for example, powder, granules or aggregates, paste, slurry, etc.

[0180] The raw material composition includes a capping agent so that the resulting zirconia composite sintered body contains a capping element or ion.

[0181] As a capping agent, any compound capable of becoming a monovalent ion (+1 valence cation or -1 valence anion) in a solvent containing water is not particularly limited, and examples include hydroxides, salts, halides (fluorides, chlorides, bromides, iodides), cyanides, etc. containing elements or ions derived from the capping agent. Each capping agent may be used individually or in combination of two or more types.

[0182] Examples of hydroxides containing capping elements or ions include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, francium hydroxide, etc.

[0183] Salts containing capping elements or ions include, for example, carbonates, bicarbonates, nitrates, hypochlorites, chlorites, chlorates, perchlorates, bromates, permanganates, metaborates, sulfides, and cyanides.

[0184] Examples of carbonates containing capping elements or ions include lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, francium carbonate, cesium carbonate, etc.

[0185] Examples of bicarbonates containing capping elements or ions include lithium bicarbonate, sodium bicarbonate, potassium bicarbonate, rubidium bicarbonate, francium bicarbonate, cesium bicarbonate, etc.

[0186] Examples of nitrates containing capping elements or ions include calcium nitrate, strontium nitrate, iron nitrate (II), iron nitrate (III), cobalt nitrate (II), magnesium nitrate, gallium nitrate, yttrium nitrate (III), lanthanum nitrate (III), praseodymium nitrate, neodymium nitrate (III), manganese nitrate (II), europium nitrate, copper nitrate (II), thorium nitrate, aluminum nitrate, nickel nitrate (II), chromium nitrate (III), titanium nitrate (IV), zirconium nitrate, zirconium oxynitrate (IV) hydrate (ZrO(NO3)2·xH2O), cerium nitrate (III), tin nitrate, bismuth nitrate (III), scandium nitrate (III), indium nitrate (III), hafnium nitrate (IV), etc.

[0187] Examples of hypochlorites containing capping elements or ions include sodium hypochlorite and calcium hypochlorite.

[0188] Examples of chlorites containing capping elements or ions include sodium chlorite, potassium chlorite, lithium chlorite, calcium chlorite, magnesium chlorite, barium chlorite, copper chlorite (II), copper chlorite (III), silver chlorite, nickel chlorite, etc.

[0189] Examples of chlorates containing capping elements or ions include calcium chlorate, barium chlorate, cobalt chlorate, nickel chlorate, magnesium chlorate, zinc chlorate, copper chlorate, etc.

[0190] Examples of perchlorates containing capping elements or ions include iron perchlorate (III), barium perchlorate, calcium perchlorate, cobalt perchlorate, nickel perchlorate, magnesium perchlorate, beryllium perchlorate, aluminum perchlorate, cerium perchlorate, etc.

[0191] Examples of bromates containing capping elements or ions include neodymium bromate, lanthanum bromide, praseodymium bromate, etc.

[0192] Examples of permanganates containing capping elements or ions include calcium permanganate (VII), potassium permanganate (VII), sodium permanganate (VII), etc.

[0193] Examples of metaborates containing capping elements or ions include sodium metaborate and barium metaborate.

[0194] Examples of sulfide salts containing capping elements or ions include copper sulfide (I).

[0195] Examples of cyanide salts containing capping elements or ions include barium cyanide, sodium cyanide, potassium cyanide, calcium cyanide, etc.

[0196] Examples of fluorides containing capping elements or ions include lithium fluoride, sodium fluoride, potassium fluoride, rubidium fluoride, cesium fluoride, francium fluoride, beryllium fluoride, magnesium fluoride, calcium fluoride, strontium fluoride, barium fluoride, scandium fluoride (III), yttrium fluoride (III), lanthanum fluoride (III), cerium fluoride (III), neodymium fluoride (III), titanium fluoride (III), titanium fluoride (IV), zirconium fluoride (IV), hafnium fluoride (IV), tantalum fluoride (V), manganese fluoride (II), manganese fluoride (III), iron fluoride (II), iron fluoride (III), copper fluoride (II), zinc fluoride (II), aluminum fluoride, chromium fluoride (III), bismuth fluoride (III), indium fluoride (III), tin fluoride (II), etc.

[0197] Chlorides containing capping elements or ions include, for example, zirconium oxychloride, lithium chloride, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, francium chloride, beryllium chloride, magnesium chloride, calcium chloride, strontium chloride, barium chloride, scandium (III) chloride, yttrium (III) chloride, lanthanum (III) chloride, cerium (III) chloride, praseodymium chloride, neodymium (III) chloride, samarium chloride, europium chloride, titanium (III) chloride, titanium (IV) chloride, zirconium (IV) chloride, hafnium (IV) chloride, tantalum (V) chloride, manganese chloride, iron (II) chloride, iron (III) chloride, cobalt (II) chloride, nickel (II) chloride, copper (I) chloride, copper (II) chloride, zinc (II) chloride, aluminum chloride, gallium chloride, and bismuth chloride. Examples include (III), indium chloride (I), indium chloride (III), tin chloride (II), etc.

[0198] Examples of bromides containing capping elements or ions include lithium bromide, sodium bromide, potassium bromide, rubidium bromide, cesium bromide, francium bromide, beryllium bromide, magnesium bromide, calcium bromide, strontium bromide, barium bromide, scandium (III) bromide, yttrium (III) bromide, cerium (III) bromide, neodymium (III) bromide, titanium (IV) bromide, zirconium (IV) bromide, tantalum (V) bromide, manganese (II) bromide, iron (II) bromide, iron (III) bromide, cobalt (II) bromide, nickel (II) bromide, copper (I) bromide, copper (II) bromide, zinc (II) bromide, chromium (III) bromide, bismuth (III) bromide, vanadium (III) bromide, indium (III) bromide, tin bromide, etc. there is.

[0199] Iodides containing capping elements or ions include, for example, lithium iodide, sodium iodide, potassium iodide, rubidium iodide, cesium iodide, francium iodide, beryllium iodide, calcium iodide, magnesium iodide, strontium iodide, barium iodide, scandium iodide (III), yttrium iodide (III), lanthanum iodide (III), cerium iodide (III), neodymium iodide (III), titanium iodide (IV), zirconium iodide (IV), hafnium iodide (IV), tantalum iodide (V), manganese iodide (II), iron iodide (II), iron iodide (III), cobalt iodide (II), nickel iodide (II), copper iodide (I), zinc iodide (II), Examples of iodides include aluminum iodide, chromium iodide (III), vanadium iodide (II), bismuth iodide (III), indium iodide (III), tin iodide (II), and tin iodide (IV).

[0200] For zirconia, commercially available zirconia powder can be used.

[0201] Commercially available products include, for example, zirconia powder (trade name "Zpex (registered trademark)" (Y2O3 content: 3 mol%), "Zpex (registered trademark) 4" (Y2O3 content: 4 mol%), "Zpex (registered trademark) Smile (registered trademark)" (Y2O3 content: 5.5 mol%), "TZ-3Y" (Y2O3 content: 3 mol%), "TZ-3YS" (Y2O3 content: 3 mol%), "TZ-4YS" (Y2O3 content: 4 mol%), "TZ-6Y" (Y2O3 content: 6 mol%), "TZ-6YS" (Y2O3 content: 6 mol%), "TZ-8YS" (Y2O3 content: 8 mol%), "TZ-10YS" (Y2O3 content: Examples include 10 mol%), “TZ-3Y-E” (Y2O3 content: 3 mol%), “TZ-3YS-E” (Y2O3 content: 3 mol%), “TZ-3YB-E” (Y2O3 content: 3 mol%), “TZ-3YSB-E” (Y2O3 content: 3 mol%), “TZ-3YB” (Y2O3 content: 3 mol%), “TZ-3YSB” (Y2O3 content: 3 mol%), “TZ-3Y20AB” (Y2O3 content: 3 mol%), “TZ-8YSB” (Y2O3 content: 8 mol%), “TZ-0” (Y2O3 content: 0 mol%); the above are manufactured by Tosho Co., Ltd.). The above commercially available zirconia powders also contain HfO2. For commercially available products, you can also use those that contain Y2O3.

[0202] As for the zirconia powder, the raw material composition of the present invention may use zirconia powder in which Y2O3 is uniformly dispersed and incorporated, such as the commercially available TZ series (which includes "TZ" in part of the product name).

[0203] There are no particular restrictions on the method of manufacturing zirconia powder, and known methods such as a breakdown process in which crude particles are crushed and pulverized, or a building-up process in which the powder is synthesized by nucleation and growth from atoms or ions, may be employed.

[0204] The type of zirconia powder in the above raw material composition is not particularly limited, and if the zirconia powder contains zirconia and does not contain a stabilizer, or if the content of the stabilizer is increased as necessary, particles of the stabilizer may be added separately. The particles of the stabilizer are not particularly limited, provided that the content of the stabilizer included in the zirconia composite sintered body can be adjusted to the aforementioned predetermined range.

[0205] For the particles of the stabilizer, for example, commercially available products may be used, or the powder of a commercially available product may be ground using a known grinding and mixing device (such as a ball mill) and then used.

[0206] The above stabilizer may be either a stabilizer that is not dissolved in zirconia or a stabilizer that is dissolved in zirconia.

[0207] In one preferred embodiment, a method for manufacturing a zirconia composite sintered body may be provided in which the stabilizer (preferably Y2O3) is not dissolved in zirconia, as a cause for easily obtaining the desired zirconia composite sintered body in the above raw material composition. That the stabilizer is not dissolved in zirconia can be confirmed, for example, by an X-ray diffraction (XRD) pattern.

[0208] If a peak originating from a stabilizer is identified in the XRD pattern of the raw material composition or the molded body, it indicates that a stabilizer that is not dissolved in zirconia is present in the raw material composition or the molded body.

[0209] When the entire amount of the stabilizer is dissolved in zirconia, peaks originating from the stabilizer are basically not observed in the XRD pattern. However, depending on conditions such as the crystal state of the stabilizer, there may be cases where the stabilizer is not dissolved in zirconia even if peaks of the stabilizer are not present in the XRD pattern.

[0210] Regarding cases where the stabilizer includes a stabilizer that is not dissolved in zirconia, yttria is used as an example of a stabilizer and is described below.

[0211] In the raw material composition or molded article of the present invention, the presence rate f of yttria not dissolved in zirconia (hereinafter referred to as "undissolved yttria") y It can be calculated based on the following mathematical formula (1).

[0212] f y = I 29 / ( I 28 + I 29 + I 30 ) × 100 (1)

[0213] (in the food, f y represents the proportion (%) of undissolved yttria, and in XRD measurement, I 28 represents the area intensity of the peak near 2θ = 28° where the main monoclinic peak appears, and I 29 represents the area intensity of the peak near 2θ = 29° where the main peak of yttria appears, and I 30 represents the area intensity of the peak near 2θ = 30°, where the main peak of the tetragonal or cubic system appears.

[0214] Also, when using a stabilizer other than yttria together, I 29 Instead, by substituting the peaks of other stabilizers, it can also be applied to the calculation of the undissolved presence rate of stabilizers other than yttria.

[0215] Presence of unemployed yttria f y From the perspective that the desired zirconia composite sintered body is easily obtained, it is preferable that it be greater than 0%, more preferable that it be 1% or more, even more preferable that it be 2% or more, and particularly preferable that it be 3% or more. Presence rate f of undissolved yttria y The upper limit may be, for example, 25% or less, but preferably depends on the content of yttria in the raw material composition or the molded body.

[0216] For example, when the content of yttria in the raw material composition or molded body of the present invention is 3 mol% or more and 8 mol% or less, it is as follows.

[0217] When the yttria content is 3 mol% or more and less than 4.5 mol%, f y can be 15% or less. When the yttria content is 4.5 mol% or more and less than 5.8 mol%, f y can be 20% or less. When the yttria content is 5.8 mol% or more and 8 mol% or less, f y It can be 25% or less.

[0218] For example, when the yttria content is 3 mol% or more and less than 4.5 mol%, f y It is desirable that it be 2% or more, more desirable that it be 3% or more, even more desirable that it be 4% or more, and particularly desirable that it be 5% or more.

[0219] When the yttria content is 4.5 mol% or more and less than 5.8 mol%, f yIt is desirable that it be 3% or more, more desirable that it be 4% or more, even more desirable that it be 5% or more, more desirable that it be 6% or more, and particularly desirable that it be 7% or more.

[0220] When the yttria content is 5.8 mol% or more and 8 mol% or less, f y It is desirable that it be 4% or more, more desirable that it be 5% or more, even more desirable that it be 6% or more, even more desirable that it be 7% or more, and particularly desirable that it be 8% or more.

[0221] In the raw material composition or molded article of the present invention, the entire stabilizer does not need to be dissolved in zirconia. Furthermore, in the present invention, the fact that the stabilizer is dissolved means, for example, that an element (atom) included in the stabilizer is dissolved in zirconia.

[0222] The Nb2O5 and / or Ta2O5 added to the raw material composition of the present invention is not particularly limited, provided that the content of Nb2O5 and / or Ta2O5 included in the zirconia composite sintered body can be adjusted to the predetermined range described above. The Nb2O5 and / or Ta2O5 are not particularly limited, and for example, commercial products may be used, or the powder of commercial products may be ground using a known grinding and mixing device (such as a ball mill) before use.

[0223] A process for preparing a raw material composition may include, for example, a method of obtaining a raw material composition by wet mixing each raw material of the raw material composition (zirconia, a stabilizer, and, if necessary, other components (at least one of Nb2O5 or Ta2O5, a capping agent (e.g., a compound that can become a monovalent ion in a solvent containing water), a zirconia reinforcing agent, etc.)) in a solvent containing water.

[0224] The method of wet mixing each of the above raw materials in a solvent containing water is not particularly limited, and for example, each raw material may be wet-mixed using a known grinding and mixing device (such as a ball mill) to form a slurry, and then the slurry may be dried and granulated to produce a granular raw material composition.

[0225] In the wet mixing process, additives such as binders, plasticizers, dispersants, emulsifiers, defoamers, pH adjusters, and lubricants may be additionally included. Each additive may be used individually or in combination of two or more types.

[0226] The above binder may be added to a slurry formed by adding a primary powder, which consists of a mixture of zirconia, Y2O3, Nb2O5 and / or Ta2O5, and a capping agent, to water and then grinding the slurry.

[0227] The above binder is not particularly limited and known binders may be used. Examples of binders include polyvinyl alcohol-based binders, acrylic-based binders, wax-based binders (paraffin wax, etc.), methylcellulose, carboxymethylcellulose, polyvinyl butyral, polymethyl methacrylate, ethylcellulose, polyethylene, polypropylene, ethylene vinyl acetate copolymer, polystyrene, atactic polypropylene, methacrylate resin, etc.

[0228] Examples of plasticizers include polyethylene glycol, glycerin, propylene glycol, dibutylphthalic acid, etc.

[0229] Examples of dispersants include, for instance, ammonium polycarboxylate (triammonium citrate, etc.), ammonium polyacrylate, acrylic copolymer resin, acrylic acid ester copolymer, polyacrylic acid, bentonite, carboxymethylcellulose, anionic surfactants (for example, polyoxyethylene alkyl ether phosphate esters such as polyoxyethylene lauryl ether phosphate ester), nonionic surfactants, olein glycerides, amine salt type surfactants, oligosaccharide alcohols, stearic acid, etc.

[0230] Examples of emulsifiers include alkyl ethers, phenyl ethers, sorbitan derivatives, etc.

[0231] Examples of antifoaming agents include alcohol, polyether, silicone, wax, etc.

[0232] Examples of pH adjusting agents include ammonia, ammonium salts (including ammonium hydroxide such as tetramethylammonium hydroxide), etc.

[0233] Examples of lubricants include polyoxyethylene alkyl ethers and waxes.

[0234] The solvent used for wet mixing is not particularly limited as long as it contains water, and may use an organic solvent, a mixed solvent of water and an organic solvent, or water alone. Examples of organic solvents include ketone solvents such as acetone and ethylmethyl ketone; alcohol solvents such as ethanol, 1-propanol, 2-propanol, 2-methyl-2-propanol, glycerin, diglycerin, polyglycerin, propylene glycol, dipropylene glycol, polypropylene glycol, ethylene glycol, diethylene glycol, polyethylene glycol, polyethylene glycol monomethyl ether, 1,2-pentanediol, 1,2-hexanediol, and 1,2-octanediol.

[0235] The raw material composition of the zirconia composite sintered body used in the present invention may contain other components other than ZrO2, Y2O3, Nb2O5, Ta2O5, capping agents, and, if necessary, zirconia reinforcing agents, as long as it exhibits the effects of the present invention. Examples of such other components include coloring agents (pigments and composite pigments), fluorescent agents, SiO2, etc. Each of the other components may be used alone or two or more may be used in combination.

[0236] The above pigment may be, for example, an oxide of at least one element selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, Zn, Y, Zr, Sn, Sb, Bi, Ce, Pr, Sm, Eu, Gd, Tb, and Er (specifically, NiO, Cr2O3, etc.), preferably an oxide of at least one element selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, Zn, Y, Zr, Sn, Sb, Bi, Ce, Pr, Sm, Eu, Gd, and Tb, and more preferably an oxide of at least one element selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, Zn, Y, Zr, Sn, Sb, Bi, Ce, Sm, Eu, Gd, and Tb. However, Y2O3 and CeO2 may be excluded from the pigment.

[0237] Examples of the above composite pigments include (Zr,V)O2, Fe(Fe,Cr)2O4, (Ni,Co,Fe)(Fe,Cr)2O4·ZrSiO4, (Co,Zn)Al2O4, etc.

[0238] The above fluorescent agents include, for example, Y2SiO5: Ce, Y2SiO5: Tb, (Y,Gd,Eu)BO3, Y2O3: Eu, YAG: Ce, ZnGa2O4: Zn, BaMgAl 10 O 17 Examples include Eu, etc.

[0239] Next, the obtained raw material composition is molded to produce a molded body. The molding method is not particularly limited, and known methods (e.g., press molding) may be used.

[0240] In the case of manufacturing a zirconia molded body by a method having a process of press-molding a raw material composition, there are no particular restrictions on the specific method of press-molding, and it can be carried out using a known press-molding machine. Specific methods of press-molding include, for example, a uniaxial press.

[0241] The press pressure is appropriately set to an optimal value according to the size of the desired molded body, open porosity, biaxial bending strength, and particle size of the raw powder, and is typically 5 MPa or more and 1000 MPa or less. By increasing the press pressure during molding in the above manufacturing method, the pores of the obtained molded body are filled more, allowing the open porosity to be set low and the density of the molded body to be increased. In addition, to increase the density of the obtained zirconia molded body, a cold isostatic pressing (CIP) treatment may be additionally performed after uniaxial pressing.

[0242] Next, the obtained molded body is sintered to obtain a zirconia composite sintered body.

[0243] The sintering temperature (maximum sintering temperature) for sintering a molded body to obtain a zirconia composite sintered body is, for example, preferably 1300 ℃ or higher, more preferably 1350 ℃ or higher, even more preferably 1400 ℃ or higher, even more preferably 1450 ℃ or higher, and particularly preferably 1500 ℃ or higher. In addition, the sintering temperature is, for example, preferably 1680 ℃ or lower, more preferably 1650 ℃ or lower, and even more preferably 1600 ℃ or lower. The method for manufacturing a zirconia composite sintered body used in the present invention preferably includes a process of sintering a molded body at a maximum sintering temperature of 1300 to 1680 ℃. The maximum sintering temperature is preferably a temperature in the atmosphere.

[0244] The holding time (holding time) at the maximum sintering temperature varies depending on the temperature, but is preferably 30 hours or less, more preferably 20 hours or less, even more preferably 10 hours or less, even more preferably 5 hours or less, particularly preferably 3 hours or less, and most preferably 2 hours or less. Additionally, the holding time may be 25 minutes or less, 20 minutes or less, or 15 minutes or less. Furthermore, the holding time is preferably 1 minute or more, more preferably 5 minutes or more, and even more preferably 10 minutes or more. According to the manufacturing method of the present invention, a zirconia composite sintered body with excellent bending strength, translucency, and machinability can be produced depending on the content of the stabilizer, Nb2O5, and / or Ta2O5. In addition, the sintering time may be shortened as long as the effects of the present invention are obtained. By shortening the sintering time, production efficiency can be increased and energy costs can be reduced.

[0245] In the method for manufacturing the above-described zirconia composite sintered body, when sintering the molded body, the heating rate is not particularly limited, but it is preferable that it be 0.1 ℃ / min or higher, more preferable that it be 0.2 ℃ / min or higher, and even more preferable that it be 0.5 ℃ / min or higher. In addition, the heating rate is preferably 50 ℃ / min or lower, more preferable that it be 30 ℃ / min or lower, and even more preferable that it be 20 ℃ / min or lower. Productivity is improved by the heating rate being above the above-described lower limit.

[0246] A general sintering furnace for dental zirconia may be used in the process of sintering the above-mentioned molded body. Commercially available products may be used as the sintering furnace for dental zirconia. Examples of commercially available products include Noritake Katana (registered trademark) F-1, F-1N, F-2, F-2N (all manufactured by SK Medical Electronics Co., Ltd.).

[0247] In addition, the process of sintering the molded body preferably includes a Hot Isostatic Pressing (HIP) treatment process in addition to sintering at the maximum sintering temperature mentioned above. By HIP treatment, the translucency and strength of the zirconia composite sintered body can be further improved.

[0248] In the following, the sintered body obtained by sintering at the maximum sintering temperature described above is referred to as the "primary sintered body," and the sintered body after HIP treatment is referred to as the "HIP-treated sintered body."

[0249] HIP treatment can be performed using a known hot hydrostatic press (HIP) device.

[0250] Although the temperature of the HIP treatment is not particularly limited, the temperature of the HIP treatment is preferably 1200°C or higher, more preferably 1300°C or higher, and even more preferably 1400°C or higher, for the reason that a dense zirconia composite sintered body with high strength can be obtained. In addition, the temperature of the HIP treatment is preferably 1700°C or lower, more preferably 1650°C or lower, and even more preferably 1600°C or lower.

[0251] In the method for manufacturing the above zirconia composite sintered body, when the first sintered body is HIP treated, the pressure of the HIP treatment is not particularly limited, and for the reason that a dense sintered body with high strength can be obtained, the pressure of the HIP treatment is preferably 100 MPa or higher, more preferably 125 MPa or higher, and even more preferably 130 MPa or higher. In addition, the upper limit of the pressure of the HIP treatment is not particularly limited, but, for example, it can be 400 MPa or lower, 300 MPa or lower, and furthermore 200 MPa or lower.

[0252] In the method for manufacturing the above zirconia composite sintered body, when the first sintered body is HIP treated, the heating rate is not particularly limited, but it is preferable that it be 0.1 ℃ / min or higher, more preferable that it be 0.2 ℃ / min or higher, and even more preferable that it be 0.5 ℃ / min or higher. In addition, the heating rate is preferably 50 ℃ / min or lower, more preferable that it be 30 ℃ / min or lower, and even more preferable that it be 20 ℃ / min or lower. Productivity is improved by the heating rate being above the above lower limit.

[0253] In the method for manufacturing a zirconia composite sintered body used in the present invention, when the primary sintered body is subjected to HIP treatment, the time of the HIP treatment is not particularly limited. In order to obtain a dense zirconia composite sintered body with high strength, the time of the HIP treatment is preferably 5 minutes or more, more preferably 10 minutes or more, and even more preferably 30 minutes or more. Furthermore, the time of the HIP treatment is preferably 10 hours or less, more preferably 6 hours or less, and even more preferably 3 hours or less.

[0254] In the method for manufacturing the above zirconia composite sintered body, when the above primary sintered body is HIP treated, the pressure medium is not particularly limited, and in order to have a low impact on zirconia, the pressure medium may be selected from at least one type selected from the group consisting of oxygen gas, oxygen mixed gas, air, and inert gas (e.g., nitrogen gas, argon gas, etc.).

[0255] When the above primary sintered body is HIP treated under an oxygen mixed gas atmosphere, the oxygen concentration is not particularly limited, but, for example, can be greater than 0% and less than or equal to 20%.

[0256] In the case of using an oxygen mixed gas, at least one type of inert gas (e.g., nitrogen gas, argon gas, etc.) can be selected as the gas other than oxygen.

[0257] In the above method for manufacturing a zirconia composite sintered body, if the process is carried out in a reducing atmosphere, such as by using an inert gas during the HIP treatment, blackening may occur due to oxygen defects. In that case, to remove the blackening, it is preferable to include a process of heat treatment at 1650°C or lower in the atmosphere or in an oxygen-rich atmosphere (hereinafter also referred to as "tempering treatment") after the HIP treatment process, and from the perspective of efficiently carrying out the heat treatment, it is more preferable to carry out the process in an oxygen-rich atmosphere.

[0258] In this specification, "oxygen-excess atmosphere" means that the oxygen concentration is higher than that of the atmosphere. As for the oxygen-excess atmosphere, the oxygen concentration is not particularly limited to 21% or more and 100% or less, and can be appropriately selected within this range. For example, the oxygen concentration may be 100%.

[0259] The zirconia composite sintered body used in the present invention is not particularly limited as long as it exhibits the effects of the present invention, and may be a primary sintered body, a HIP-treated sintered body, or a sintered body after tempering treatment.

[0260] One preferred embodiment may be a zirconia composite sintered body, which is a sintered body after tempering treatment.

[0261] Depending on the aesthetics of the zirconia composite sintered body (e.g., shade of a dental prosthesis), the temperature of the heat treatment in the atmosphere or in an oxygen-rich atmosphere can be appropriately changed.

[0262] In one preferred embodiment, the temperature of the heat treatment in the atmosphere or in an oxygen-rich atmosphere is preferably 1650°C or lower, more preferably 1600°C or lower, and even more preferably 1550°C or lower for the aesthetics of the zirconia composite sintered body.

[0263] In another preferred embodiment, the temperature of the heat treatment in air or an oxygen-rich atmosphere is preferably 1400°C or lower, more preferably 1300°C or lower, and even more preferably 1200°C or lower for the aesthetics of the zirconia composite sintered body.

[0264] In addition, in any embodiment, the temperature of the heat treatment is preferably 500°C or higher, more preferably 600°C or higher, and even more preferably 700°C or higher.

[0265] For the above tempering treatment, a general kiln for dental zirconia may be used. Commercially available products may be used as the kiln for dental zirconia. Examples of commercially available products include Noritake Katana (registered trademark) F-1, F-1N, F-2 (all manufactured by SK Medical Electronics Co., Ltd.).

[0266] Since the zirconia composite sintered body used in the present invention has excellent machinability despite being a sintered body, there is no need to machine a mill blank of a semi-sintered plastic body and then sinter it to form a sintered body.

[0267] Meanwhile, as a method for manufacturing a zirconia composite sintered body, a molded body obtained using the above raw material composition may be plasticized to produce a plastic body in a semi-sintered state, and then the unprocessed plastic body is mechanically processed to form a sintered body.

[0268] Another method for manufacturing a zirconia composite sintered body includes a process for manufacturing a molded body using the above raw material composition, a process for obtaining a zirconia composite plastic by plasticizing the obtained molded body (plasticization process), and a process for sintering the zirconia composite plastic.

[0269] In order to ensure block formation, the sintering temperature (sintering temperature) in the sintering process is, for example, preferably 800°C or higher, more preferably 900°C or higher, and even more preferably 950°C or higher.

[0270] In addition, the calcination temperature is preferably, for example, 1200°C or lower, more preferably 1150°C or lower, and even more preferably 1100°C or lower. As for the calcination temperature, for example, 800°C to 1200°C is preferred. At such calcination temperatures, it is thought that the solid solution of the stabilizer does not proceed significantly during the calcination process.

[0271] The density of the zirconia composite plastic is preferably 2.7 g / cm³ or higher. In addition, the density of the zirconia composite plastic is preferably 4.0 g / cm³ or lower, more preferably 3.8 g / cm³ or lower, and even more preferably 3.6 g / cm³ or lower. When within this density range, processing can be easily performed. The density of the composite plastic can be calculated, for example, as (mass of the composite plastic) / (volume of the composite plastic).

[0272] In addition, the three-point bending strength of the zirconia composite plastic is preferably 15 to 70 MPa, more preferably 18 to 60 MPa, and even more preferably 20 to 50 MPa.

[0273] The above bending strength may be measured using a test specimen with a thickness of 5 mm × width of 10 mm × length of 50 mm, in accordance with ISO 6872:2015 except for the size of the test specimen. The face and C-face (the face where the corner of the test specimen is chamfered at a 45° angle) of the test specimen are finished in the longitudinal direction with 600-grit sandpaper. The test specimen is positioned so that its widest face faces the vertical direction (load direction). For the bending test measurement, the span is 30 mm and the crosshead speed is 1.0 mm / min.

[0274] The process of sintering the zirconia composite plastic can be carried out under the same method and conditions (temperature, pressure, etc.) as the process of sintering the molded body described above. Therefore, in an embodiment of a manufacturing method using a zirconia composite plastic, the "molded body" may be replaced with the "plastic."

[0275] The zirconia composite sintered body used in the present invention has excellent strength. The biaxial bending strength of the zirconia composite sintered body used in the present invention is preferably 300 MPa or more, more preferably 350 MPa or more, even more preferably 400 MPa or more, more preferably 450 MPa or more, and particularly preferably 500 MPa or more. By having such biaxial bending strength, the zirconia composite sintered body used in the present invention can suppress fracture in the oral cavity, for example, when used as a dental prosthesis. Although there is no particular limit on the upper limit of the said biaxial bending strength, said biaxial bending strength can be, for example, 1200 MPa or less, and furthermore, 1000 MPa or less. In addition, the biaxial bending strength of the zirconia composite sintered body can be measured in accordance with ISO 6872:2015.

[0276] It is preferable that the zirconia composite sintered body used in the present invention has high light transmittance. Light transmittance can be evaluated as ΔL*. Specifically regarding light transmittance, it is preferable that the zirconia composite sintered body used in the present invention has a diameter of 15 mm and a thickness of 1.2 mm, and the ΔL* is 10 or higher, more preferable that it is 12 or higher, even more preferable that it is 13 or higher, and particularly preferable that it is 14 or higher. By having the said ΔL* within the above range, a zirconia composite sintered body with high light transmittance is obtained.

[0277] ΔL* refers to the difference between the lightness on a white background (the first L* value) and the lightness on a black background (the second L* value) for the same sample. Specifically, it refers to the difference between the L* value on a white background (JIS Z 8781-4: 2013 Colorimetry - Part 4: CIE 1976 L*a*b* color space) and the L* value on a black background. A white background refers to the white part of the opacity test paper described in Section 1, Part 4 of JIS K 5600-4-1: 1999, and a black background refers to the black part of the opacity test paper.

[0278] There is no specific limit on the upper limit of ΔL*, but for example, it can be 25 or less, or furthermore, 20 or less in terms of aesthetics.

[0279] In addition, ΔL* at a diameter of 15 mm and a thickness of 1.2 mm of a zirconia composite sintered body can be measured using a spectrophotometer, for example, using a dental colorimeter ("CrystalEye CE100-CE / JP", 7-band LED light source, analysis software "CrystalEye" (manufactured by Olympus Corporation)).

[0280] In addition, the zirconia composite sintered body used in the method for manufacturing a dental prosthesis of the present invention comprises zirconia and a stabilizer capable of suppressing the phase transition of zirconia, and

[0281] In a total of 100 mol% of zirconia, the above stabilizer, Nb2O5, and Ta2O5,

[0282] The zirconia content is 78 to 97.5 mol%, and

[0283] The content of the above stabilizer is 1 to 12 mol%, and

[0284] When the content of Nb2O5 and / or Ta2O5 is 1 to 9 mol%, the zirconia composite sintered body described above can be manufactured in the same manner as the method for manufacturing a zirconia composite sintered body in which a capping element or ion is included, except that the raw material composition does not include a capping agent.

[0285] In addition, depending on the content of each component and / or the crystal system of zirconia, a zirconia composite sintered body may be manufactured in accordance with the manufacturing method disclosed in International Publication No. 2021 / 132644.

[0286] Dental prostheses manufactured from the zirconia composite sintered body used in the present invention include, for example, crown restorations such as inlays, onlays, veneers, crowns, core-integrated crowns, and bridges, as well as abutment teeth, dental posts, dentures, denture bases, and implant components (fixtures, abutments). In addition, it is preferable to perform machining using, for example, a commercially available dental CAD / CAM system. Examples of such CAD / CAM systems include the "CEREC system" manufactured by Dentsply Sirona Dental Systems Co., Ltd. and the "Katana (registered trademark) system" manufactured by Kurare Noritake Dental Co., Ltd.

[0287] In addition, the zirconia composite sintered body used in the present invention can be used for applications other than dental use, and is particularly preferably used in zirconia members requiring irregular or complex shapes and strength.

[0288] Compared to sintered bodies produced solely by conventional manufacturing methods (injection molding, CIP, injection molding, or 3D printing, etc.), the zirconia composite sintered body used in the present invention can be processed as is. Therefore, for example, it is economical when a desired zirconia member is obtained in a short time, and in the case of complex shaped parts that are difficult to manufacture by conventional manufacturing methods, it is possible to obtain a zirconia member that maintains high strength because there is no need to obtain multiple members by mechanical fitting. Furthermore, since the sintered body can be processed as is, the sintering process is unnecessary when dimensional accuracy is required, and since non-uniform plastic shrinkage is eliminated, the zirconia member is obtained with high precision. Specifically, it can be used as a method for manufacturing parts for jewelry decoration, engine and interior parts for mobility such as aircraft and automobiles, frame materials for display panels, architectural parts, electrical product parts, household goods parts, and toys.

[0289] In addition, the zirconia component may be fitted with a heterogeneous material and used as a composite component.

[0290] The present invention includes embodiments in which all or part of the above-mentioned components are combined in various ways within the scope of the technical concept of the present invention, as long as they produce the effects of the present invention.

[0291] Examples

[0292] The present invention will be explained more specifically below with reference to examples, but the present invention is not limited in any way by these examples, and many modifications are possible by those skilled in the art within the scope of the technical concept of the present invention.

[0293] [Examples 1–20 and Comparative Examples 1–6]

[0294] The measurement samples of each example and comparative example were prepared through the process of preparing a granular raw material composition, preparing a molded body, and preparing a sintered body (preparation of a primary sintered body, HIP treatment, and tempering treatment).

[0295] [Preparation of granular raw material composition]

[0296] To prepare the granular raw material compositions of each example and comparative example, at least one of commercially available ZrO2 powder, Y2O3 powder, Nb2O5 powder, or Ta2O5 powder, additionally a capping agent as needed, and TiO2 powder were mixed such that the content of each component in the zirconia composite sintered body after sintering was the composition described in Tables 1 to 3, water was added to prepare a slurry, and wet-milled and mixed using a ball mill until the average particle size was 0.13 μm or less. After adding a binder to the slurry after milling, the mixture was dried with a spray dryer to prepare a granular raw material composition (hereinafter also simply referred to as the "raw material composition"), which was used to manufacture the molded body described below.

[0297] The above average particle size is a value measured on a volume basis by using a laser diffraction / scattering particle size distribution measuring device (Partica LA-950: manufactured by Horiba Corporation), ultrasonically irradiating a slurry diluted with water for 30 minutes, and then applying ultrasound.

[0298] [Manufacturing of molded bodies]

[0299] For each example and comparative example, a block-shaped molded body was prepared as follows so that a sintered body sample for surface roughness evaluation and glaze sintering evaluation could be obtained.

[0300] First, the above raw material composition was placed into a mold with inner dimensions of 19 mm × 18 mm so that the thickness of the zirconia composite sintered body after sintering was 14.5 mm.

[0301] Next, the raw material composition was press-molded by a single-axis press molding machine at a surface pressure of 200 MPa for 90 seconds to produce a block-shaped molded body.

[0302] [Preparation of 1st Sintered Body]

[0303] For the obtained block-shaped molded body, a sample of a block-shaped zirconia composite sintered body (primary sintered body) was obtained by using the "Noritake Katana (registered trademark) F-1" sintering furnace manufactured by SK Medical Electronics Co., Ltd. and holding it in the atmosphere at a maximum sintering temperature of 1550 ℃ for 2 hours.

[0304] [Manufacture of HIP-treated sintered bodies]

[0305] With respect to the obtained block-shaped zirconia composite sintered body (primary sintered body), a sample of a block-shaped zirconia composite sintered body (HIP-treated sintered body) was obtained by holding the obtained block-shaped zirconia composite sintered body (primary sintered body) at 1450°C and 150 MPa for 2 hours under an argon atmosphere using the HIP device "O2-Dr. HIP" manufactured by Kobe Steel Corporation.

[0306] [Manufacture of Zirconia Composite Sintered Body (Sintered Body after Tempering Treatment)]

[0307] With respect to the obtained block-shaped zirconia composite sintered body (HIP-treated sintered body), a sample of a block-shaped zirconia composite sintered body (sintered body after tempering treatment) was obtained by holding it at 700°C for 60 hours using the "Noritake Katana (registered trademark) F-1" kiln manufactured by SK Medical Electronics Co., Ltd. The size of the obtained block-shaped sample was width 15.7 mm × length 16.5 mm × height 14.5 mm.

[0308] [Manufacturing of desired shape using a wet machining process]

[0309] For each example, a sample of a block-shaped zirconia composite sintered body (sintered body after tempering treatment) was prepared by attaching a metal jig to a surface with a width of 15.7 mm × a height of 14.5 mm, and the sample was processed into an incisor, premolar, and molar shape as a sample for evaluating glaze sintering using the CEREC system “MC-XL” (manufactured by Dentsply Sirona).

[0310] The processing program used the software "inLab (registered trademark) CAM version 20.0.1.203841", Manufacture: IVOCLAR VIVADENT, Material name: IPS e.max CAD, Production Method: Grinding, Block size: C16, and the processing tools used were Step Bur 12 and Cylinder Pointed Bur 12S.

[0311] [Pretreatment for Substrate (Zirconia Composite Sintered Body)]

[0312] For the machined sintered body manufactured by the method described in [Manufacturing of desired shape with wet processing machine] above, Examples 1 to 7, 12, 13, 15, and 17 to 19 performed the heat treatment described in Table 1 on the machined sintered body.

[0313] Examples 8 to 11, 14, 16, and 20 involved performing a polishing treatment on the machined sintered body. As for the dental polishing material used for the polishing treatment, Example 8 used "EVE Diapol Twist Medium" (manufactured by EVE Corporation), Examples 9, 11, 14, 16, and 20 used "Pearl Surface Z" (manufactured by Kuraray Noritake Dental Co., Ltd.), and Example 10 used "Meister Con S-Green" (manufactured by Kuraray Noritake Dental Co., Ltd.).

[0314] [Method for Measuring Surface Roughness Ra of a Sintered Body]

[0315] Surface roughness Ra was evaluated using the crown-shaped sintered bodies of Examples 8 to 11, 14, 16, and 20, which underwent the above pretreatment. Specifically, it was evaluated by the following method.

[0316] The surface of the crown-shaped sintered body was observed under the following conditions using a color 3D laser microscope (product name "VK-9710", manufactured by Keyence Co., Ltd.).

[0317] Measurement pitch: 2 µm

[0318] Measurement distance: 1058 µm

[0319] The obtained image was analyzed using image analysis software (product name "VK Analyzer", manufactured by Keyence Co., Ltd.) to calculate the surface roughness, and the surface roughness was set as Ra (arithmetic mean value of n = 3).

[0320] [Evaluation of Glaze Firing]

[0321] In the following manner, the sintered body of the example that underwent the above pretreatment and the sintered body of the comparative example as is after processing were subjected to the ceramic material described in Tables 1 to 3, and firing was performed.

[0322] First, the porcelain was applied or sprayed onto the crown-shaped sintered body according to the method specified in the handling instructions for each porcelain. At that time, the porcelain was applied to cover the entire surface of the substrate so that the surface of the substrate was not partially exposed. In addition, the thickness of the porcelain to be built up was set to 10 to 50 μm after firing. Then, the porcelain was fired in a dental kiln (product name "Cerafusion BX", manufactured by SK Medical Electronics Co., Ltd.) using a firing program specified in the handling instructions for each porcelain. The surface of the obtained evaluation samples was observed to check for the presence or absence of fusing defects, and the results are listed in Tables 1 to 3.

[0323] The glaze firing was evaluated based on the following criteria.

[0324] P: In the frontal and occlusal surfaces, no delamination of the glazed porcelain from the substrate is observed.

[0325] F: In the frontal or occlusal surface, delamination from the glazed porcelain substrate is observed.

[0326] "P" means Pass, and "F" means Fail.

[0327] In addition, the content of each component of the sintered body in Tables 1 to 3 is a value calculated from the amount of raw material input.

[0328] The content (mol%) of capping elements or ions (e.g., Na) in Tables 1 to 3 is the external addition rate to the total of 100 mol% of zirconia (sum of ZrO2 and HfO2), the stabilizer (yttria), Nb2O5, and Ta2O5.

[0329] The respective content percentages (mol%) of zirconia (total of ZrO2 and HfO2), the stabilizer, Nb2O5, and Ta2O5 in Tables 1 to 3 are the content percentages of each component in the total of zirconia, the stabilizer, Nb2O5, and Ta2O5 at 100 mol%.

[0330] The content of TiO2 and Al2O3 (mass%) in Tables 1 to 3 is the external addition rate relative to the total of 100 mass% of zirconia, the stabilizer, Nb2O5, and Ta2O5.

[0331] "A / B" in Tables 1 to 3 represents the ratio of A to B when the content of Y2O3 is A mol% and the total content of Nb2O5 and Ta2O5 is B mol%.

[0332]

[0333]

[0334]

[0335] From the above results, the zirconia composite sintered body related to Examples 1 to 20 can perform porcelain fusing well even in dental prostheses having complex shapes, such as many curved surfaces and many grooves in the occlusal surface, as well as molars, as shown in FIG. 2A or FIG. 2B, as well as incisors and premolars, and the dental prostheses have excellent aesthetics.

[0336] In contrast, in the zirconia composite sintered bodies related to Comparative Examples 1 to 6, peeling from the glazed ceramic substrate was observed in the frontal or occlusal surfaces, as shown in the black circle in Fig. 3A or Fig. 3B, and the aesthetics were poor.

[0337] Industrial applicability

[0338] The zirconia composite sintered body used in the present invention has desirable strength and transparency, and also has excellent machinability. In particular, it is useful as a dental material, such as a dental prosthesis intended for dental treatment.

Claims

Claim 1 A method for manufacturing a dental prosthesis comprising: a process of performing heat treatment or polishing treatment as a pretreatment on a zirconia composite sintered body containing Nb2O5 and / or Ta2O5; and a process of building up a porcelain on the zirconia composite sintered body that has undergone the pretreatment and firing it. Claim 2 A method for manufacturing a dental prosthesis according to claim 1, wherein the temperature of the heat treatment is 150 ℃ or higher and 1550 ℃ or lower. Claim 3 A method for manufacturing a dental prosthesis according to claim 1, wherein, in the polishing treatment, the surface roughness Ra of the zirconia composite sintered body after the polishing treatment is 8.0 μm or less. Claim 4 A method for manufacturing a dental prosthesis according to claim 1 or 2, wherein the zirconia composite sintered body comprises zirconia and a stabilizer capable of suppressing the phase transition of zirconia, and wherein, in a total of 100 mol% of zirconia, the stabilizer, Nb2O5, and Ta2O5, the content of zirconia is 78 to 97.5 mol%, the content of the stabilizer is 1 to 12 mol%, and the content of Nb2O5 and / or Ta2O5 is 1 to 9 mol%. Claim 5 A method for manufacturing a dental prosthesis according to claim 4, wherein the zirconia composite sintered body further comprises an element or ion derived from a capping agent. Claim 6 A method for manufacturing a dental prosthesis according to claim 5, wherein the content of an element or ion derived from the capping agent is greater than 0 mol% and less than or equal to 5 mol% with respect to 100 mol% of the total of zirconia, the stabilizer, Nb2O5, and Ta2O5. Claim 7 A method for manufacturing a dental prosthesis according to claim 5, wherein the element or ion derived from the capping agent belongs to the 2nd to 7th periods of the periodic table, and the first ionization energy is smaller than that of a Group 18 element of the same period or the element or ion thereof, and / or an element or ion thereof with high electron affinity. Claim 8 A method for manufacturing a dental prosthesis according to claim 5, wherein the element or ion derived from the capping agent comprises at least one element or ion selected from the group consisting of Cu, Ag, Li, Na, K, Rb, Cs, Fr, At, I, Br, Cl, and F. Claim 9 A method for manufacturing a dental prosthesis according to claim 5, wherein the element or ion derived from the capping agent comprises at least one element or ion selected from the group consisting of Li, Na, K, Rb, Cs, and Fr. Claim 10 A method for manufacturing a dental prosthesis according to claim 4, wherein the content of the stabilizer is A mol% and the total content of Nb2O5 and Ta2O5 is B mol%, and the ratio of A / B is 0.9 or more and 3 or less. Claim 11 A method for manufacturing a dental prosthesis according to claim 4, wherein the stabilizer comprises Y2O3 and / or CeO2. Claim 12 A method for manufacturing a dental prosthesis according to claim 4, wherein additionally comprising a zirconia reinforcing agent, the content of said zirconia reinforcing agent is greater than 0 mass% and less than or equal to 6.0 mass% with respect to 100 mass% of the total of zirconia, said stabilizer, Nb2O5, and Ta2O5. Claim 13 A method for manufacturing a dental prosthesis according to claim 12, wherein the zirconia reinforcing agent comprises TiO2 and / or Al2O3. Claim 14 A method for manufacturing a dental prosthesis according to claim 13, wherein the zirconia reinforcing agent comprises TiO2, and the TiO2 content is 0.6 to 4.5 mass%. Claim 15 A method for manufacturing a dental prosthesis according to claim 1 or 2, wherein the average crystal grain size of the zirconia composite sintered body is 0.5 to 5.0 μm.

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