JP2020075858A - Zirconia calcinated body and zirconia sintered body, and laminate - Google Patents

Abstract

To provide a zirconia sintered body having suppressed irregular shrinkage deformation.SOLUTION: A zirconia calcinated body is formed by burning a laminate comprising a plurality of zirconia layers containing zirconia and a stabilizer for suppressing a phase transition of zirconia and having different compositions, wherein: when a test piece is prepared by molding the resulting zirconia calcinated body to a rectangular solid shape with dimension of width 50 mm×height 10 mm×depth 5 mm, the test piece having a surface as a bottom surface with dimension of width 50 mm×depth 5 mm, a border surface formed by the plurality of zirconia layers is in parallel to the bottom surface; when the test piece is burned at 1,500°C for 2 hours and is placed with a bottom surface deformed into a concave surface facing down out of two bottom surfaces, (maximum intervals between a bottom surface deformed into the concave surface and a ground surface)/(distance between grand parts in a width direction)×100 is 0.15 or less; and 0-0.3 mass% of aluminum oxide is contained based on the total mass of the zirconia and the stabilizer.SELECTED DRAWING: None

Description

  The present invention relates to a zirconia calcined body. The present invention also relates to a zirconia sintered body produced from a zirconia calcined body. Furthermore, the present invention relates to a laminate including a plurality of zirconia layers having different compositions.

Ceramics such as a sintered body of zirconium (IV) oxide (ZrO ₂ ) (hereinafter referred to as “zirconia”) are used in various fields. For example, a zirconia sintered body having high strength is applied to a dental prosthesis material, a tool, and the like.

  Such ceramics are manufactured by sintering a green body powder compact or a calcined body thereof. In the sintering process, the compact and the calcined body shrink. Therefore, the size of the compact or the calcined body and the size of the sintered body are different. Then, the method of reducing the influence by baking shrinkage is disclosed (for example, refer to Patent Documents 1 to 3).

  Patent Document 1 discloses a method for producing a ceramics sintered body, in which a starting material is mixed with a stabilizer, a sintering aid, etc., and a binder is added, and the resulting material is molded and fired. Obtain the relationship between the average particle size and the shrinkage during firing, prepare molding dies with different dimensions according to each shrinkage, and determine the average particle size of the mixed raw material before the binder addition during main molding. A method for producing a ceramics sintered body is disclosed, in which the ceramics sintered body is measured, molded using a molding die corresponding to the shrinkage ratio obtained from the average particle diameter, and fired.

  In Patent Document 2, a starting material is mixed with a stabilizer, a sintering aid, etc., and a binder is added to form a pre-forming material. Then, after measuring the dimension of the specific portion of the ceramic molded body or the dimension of the specific portion of the molding die, it is dried or fired, and the dimension of the specific portion of the ceramic dried body or the ceramic sintered body is measured again, After performing a preliminary test to calculate the shrinkage rate, select a molding die based on the shrinkage rate calculated above so that the specific location of the ceramics sintered body will have the desired dimensions, then perform the main forming and the main firing. A method for producing a ceramics sintered body is disclosed.

  Patent Document 3 discloses a method of sintering a ceramic molded object with high dimensional fidelity, in which the fired product is supported on a non-metal-coated support material during sintering, and the support material is generated during the firing process. A dimensional-accurate sintering method for ceramic shaped objects is disclosed, which automatically adapts to shrinkage or allows the contacting of shaped objects in a contactless manner.

  When the zirconia sintered body is used for an artificial tooth as a substitute for a natural tooth, the artificial tooth is required to have the same appearance as the natural tooth. As a technique for trimming the appearance of artificial teeth, US Pat. No. 6,037,049 discloses a multi-colored shaped body having layers arranged on top of each other for producing a dental restoration. The molded body described in Patent Document 4 has (a) at least two continuous and different color main layers, and (b) at least two between the at least two continuous and different color main layers. With different color interlayers, the change in color between these interlayers occurs in a direction that is opposite to the direction of the change in color between the main layers.

JP, 2003-137651, A JP, 2003-73164, A Japanese Patent Publication No. 2002-536279 JP, 2008-68079, A

  The following analysis is given in terms of the present invention.

  High dimensional accuracy may be required depending on the type of product to which the zirconia sintered body is applied. For example, in the case of an artificial tooth used for dental treatment, the artificial tooth cannot be applied to the patient unless the shape and the size of the artificial tooth and the size and the shape of the abutment tooth of the patient whose data has been collected in advance match.

  If the shape and dimensions of the sintered body differ from the planned shape and dimensions, it may be possible to adjust it to the desired shape and dimensions by processing such as cutting and grinding, but since the zirconia sintered body has high strength, processing is not possible. It is not easy, and it is necessary to re-manufacture especially when the adjustment amount is large. In this case, manufacturing time and product cost increase.

  The methods described in Patent Documents 1 to 3 require labor and new manufacturing equipment, and even if a sintered body having a desired size can be obtained, an increase in manufacturing time and manufacturing cost cannot be avoided. In particular, when manufacturing an artificial tooth, since the artificial tooth is a single piece, the cost of the product becomes very high if a die for it is manufactured as in Patent Documents 1 and 2.

  Further, during heat treatment or sintering of a molded body having a laminated structure as described in Patent Document 4, peeling between layers and distorted shrinkage deformation may occur. Such peeling and deformation cannot be prevented by the methods described in Patent Documents 1 to 3.

  According to a first aspect of the present invention, a zirconia calcined body containing a zirconia and a stabilizer that suppresses a phase transition of zirconia and firing a laminate composed of a plurality of zirconia layers having different compositions, When the zirconia calcined body was molded into a rectangular parallelepiped shape having a width of 50 mm, a height of 10 mm, and a depth of 5 mm, it was used as a test piece, and in the test piece, a surface having a width of 50 mm and a depth of 5 mm was used as a bottom surface. The boundary surface formed by the zirconia layer is parallel to the bottom surface, and the test piece was fired at 1500 ° C. for 2 hours, and the test piece was placed with the bottom surface of the two bottom surfaces deformed into a concave surface facing downward. At this time, (maximum distance between the bottom surface deformed into a concave surface and the ground contact surface) / (distance between ground contact portions in the width direction) × 100 is 0.15 or less, and the total mass of the zirconia and the stabilizer is On the other hand, it contains aluminum oxide in an amount of 0% by mass to 0.3% by mass.

  According to a second aspect of the present invention, a zirconia calcined body containing a zirconia and a stabilizer that suppresses a phase transition of zirconia, and firing a laminate composed of a plurality of zirconia layers having different compositions, The test piece of the zirconia calcined body was prepared, and the load of the three-point bending test was applied to the test piece in which the boundary between layers crossed the test piece along the load application direction in accordance with JISR1601. The bending strength measured in accordance with the position of the boundary is 90% or more of the bending strength of the zirconia calcined body composed of one of the plurality of zirconia layers, and the total mass of the zirconia and the stabilizer is On the other hand, it contains aluminum oxide in an amount of 0% by mass to 0.3% by mass.

  According to a third aspect of the present invention, a zirconia calcined body containing a zirconia and a stabilizer that suppresses a phase transition of zirconia and firing a laminate composed of a plurality of zirconia layers having different compositions, A test piece of a zirconia sintered body manufactured by firing the zirconia calcined body at 1400 to 1600 ° C. is produced, and the boundary between layers crosses the test piece along the load application direction in accordance with JISR1601. The bending strength measured by matching the load point of the three-point bending test to the position of the boundary with respect to the test piece existing in the test piece is a zirconia calcined body composed of one of the plurality of zirconia layers. 90% or more of the bending strength of the zirconia sintered body sintered at the same temperature as the sintering temperature, and 0 mass% to 0.3 mass% of aluminum oxide with respect to the total mass of the zirconia and the stabilizer. contains.

  According to a fourth aspect of the present invention, a zirconia sintered body, which comprises a zirconia and a stabilizer that suppresses a phase transition of zirconia, and is obtained by firing a laminate including a plurality of zirconia layers having different compositions, A test piece of the zirconia sintered body was prepared, and a load of a three-point bending test was applied to the test piece in which a boundary between layers exists so as to cross the test piece along the load application direction in accordance with JISR1601. The bending strength measured in accordance with the position of the boundary is 90% or more of the bending strength of the zirconia sintered body consisting of one of the plurality of zirconia layers, and the total mass of the zirconia and the stabilizer is On the other hand, it contains aluminum oxide in an amount of 0% by mass to 0.3% by mass.

  According to a fifth aspect of the present invention, a zirconia and a stabilizer that suppresses a phase transition of zirconia are contained, and the zirconia layer is composed of a plurality of zirconia layers having different compositions. A laminate containing 0 mass% to 0.3 mass% of aluminum, which is a zirconia calcined body according to the first aspect by firing at 800 to 1200 ° C, and / or at 1400 to 1600 ° C. By firing, the zirconia sintered body according to the fourth aspect is obtained.

  The present invention has at least one of the following effects.

  According to the zirconia calcined body of the present invention, it is possible to obtain a zirconia sintered body having high dimensional accuracy even when a zirconia powder having different compositions is laminated to manufacture a zirconia calcined body.

The schematic diagram of the test piece for measuring the deformation amount at the time of sintering. The schematic diagram of the test piece for measuring the deformation amount at the time of sintering. The schematic diagram for demonstrating the measuring method of the amount of deformation. The schematic diagram for demonstrating a three-point bending test method. The schematic diagram of a zirconia sintered compact. The schematic diagram of a test piece in Example 5, and a measurement result. The schematic diagram and measurement result of the test piece in the comparative example 3.

  A preferable form of each of the above viewpoints will be described below.

  According to the preferred mode of the first aspect, (the maximum distance between the bottom surface deformed into a concave surface and the ground contact surface) / (the distance between the ground contact portions in the width direction) × 100 is 0.1 or less.

  According to the preferable mode of the first aspect, the plurality of zirconia powders contain pigments, and the content rates of the pigments are different from each other.

According to the preferable mode of the second aspect, the L ^* a ^* b ^* table of the first point in a section from one end to 25% of the entire length on a straight line extending from one end to the other in the first direction. The chromaticity (L ^* , a ^* , b ^* ) by the color system is (L1, a1, b1), and the second point L ^* a ^* b ^* color system in the section from the other end to 25% of the total length. When the chromaticity (L ^* , a ^* , b ^* ) according to is (L2, a2, b2), L1 is 58.0 or more and 76.0 or less, and a1 is -1.6 or more and 7.6 or less. Yes, b1 is 5.5 or more and 26.7 or less, L2 is 71.8 or more and 84.2 or less, a2 is -2.1 or more and 1.8 or less, and b2 is 1.9 or more and 16. 0 or less, L1 <L2, a1> a2, b1> b2, and the increasing / decreasing tendency of chromaticity due to the L ^* a ^* b ^* color system changes from the first point to the second point. do not do.

According to the preferable mode of the second viewpoint, there is no section where the L ^* value decreases by 1 or more from the first point to the second point on the straight line connecting the first point and the second point, There is no section where the a ^* value increases by 1 or more from the 1st point to the 2nd point, and there is no section where the b ^* value increases by 1 or more from the 1st point to the 2nd point.

According to the preferable mode of the second viewpoint, on the straight line connecting the first point and the second point, the color of the third point L ^* a ^* b ^* colorimetric system between the first point and the second point is obtained. When the degree (L ^* , a ^* , b ^* ) is (L3, a3, b3), L3 is 62.5 or more and 80.5 or less, and a3 is -1.8 or more and 5.5 or less, b3 is 4.8 or more and 21.8 or less, L1 <L3 <L2, a1>a3> a2, and b1>b3> b2.

According to the preferable mode of the second viewpoint, on the straight line connecting the first point and the second point, the color of the fourth point between the third point and the second point by the L ^* a ^* b ^* color system. When the degree (L ^* , a ^* , b ^* ) is (L4, a4, b4), L4 is 69.1 or more and 82.3 or less, and a4 is -2.1 or more and 1.8 or less, b4 is 3.5 or more and 16.2 or less, a1>a3>a4> a2, and b1>b3>b4> b2.

  According to the preferable mode of the second viewpoint, the third point is at a distance of 45% of the entire length from one end. The fourth point is 55% of the total length from one end.

According to the preferable mode of the second viewpoint, at the first point, the third point, the fourth point, and the second point, the difference between the L ^* values at the two adjacent points is ΔL ^*, and the a ^{* at} the two adjacent points is set ^. the difference between the value and .DELTA.a ^*, if the difference in ^{b *} values in 2 adjacent points and [Delta] b ^*, which was calculated from the Delta] E ^* ab formula 1 below, the first point and the Delta] E ^* ab between a third point 3 0.7 or more and 14.3 or less, ΔE ^* ab between the third point and the fourth point is 1.8 or more and 17.9 or less, and ΔE ^* ab between the fourth point and the second point is 1.0. It is above 9.0.

Formula 1

According to the preferable mode of the second viewpoint, on the straight line connecting the first point and the second point, the color of the third point L ^* a ^* b ^* colorimetric system between the first point and the second point is obtained. When the degree (L ^* , a ^* , b ^* ) is (L3, a3, b3), L3 is 69.1 or more and 82.3 or less, and a3 is -2.1 or more and 1.8 or less, b3 is 3.5 or more and 16.2 or less, L1 <L3 <L2, a1>a3> a2, and b1>b3> b2.

According to the preferable mode of the second aspect, the color changes in the first direction from one end to the other end, and the color according to the L ^* a ^* b ^* color system is on a straight line from one end to the other end. The increase / decrease tendency does not change.

According to the preferable mode of the second viewpoint, on the straight line connecting the one end and the other end, the L ^* value tends to increase from the first point to the second point, and the a ^* value and the b ^* value decrease. There is a tendency.

  According to the preferable mode of the second viewpoint, the distance from one end to the other end is 5 mm to 18 mm.

  According to the preferable mode of the second viewpoint, the color does not change along the second direction orthogonal to the first direction.

According to the preferable mode of the second viewpoint, at two points on a straight line extending in the second direction, the difference between the L ^* values between the two points is ΔL ^*, and the difference between the a ^* values between the two points is Δa. ^When ΔE ^* ab is calculated from the above equation 1 with ^* , the difference between the b ^* values between the two points is Δb ^*, and ΔE ^* ab is less than 1.

  According to the preferable mode of the second aspect, the bending strength measured according to JIS R1601 is 1000 MPa or more.

According to the preferable mode of the second aspect, the fracture toughness measured according to JIS R1607 is 3.5 MPa · m ^1/2 or more.

  According to the preferable mode of the second aspect, in the X-ray diffraction pattern of the zirconia sintered body after being subjected to the hydrothermal treatment test at 180 ° C. and 1 MPa for 5 hours, 2θ is around 30 ° and tetragonal-derived [111]. The ratio of the height of the peak existing near the position where the peak occurs to the position where the [11-1] peak derived from the monoclinic crystal having 2θ of about 28 ° to the height of the peak existing near the position where the peak occurs is 1 or less.

  According to the preferable mode of the fifth aspect, the cutting process is performed using the CAD / CAM system.

  In the present invention, for example, when the zirconia sintered body has a crown shape, it is preferable that the “one end” and the “other end” refer to one point of the end on the cut end side and one point of the end on the root side. The one point may be one point on the end face or one point on the cross section. The point in the section from one end or the other end to 25% of the total length means, for example, a point separated from the one end or the other end by a distance corresponding to 10% of the height of the crown.

  When the zirconia sintered body has a hexahedral shape such as a disk shape or a rectangular parallelepiped shape, it is preferable that the “one end” and the “other end” refer to one point on the upper surface and the lower surface (bottom surface). The one point may be one point on the end face or one point on the cross section. The point in the section from one end or the other end to 25% of the total length is, for example, a point separated from the one end or the other end by a distance corresponding to 10% of the thickness of the hexahedron or the disc.

  In the present invention, the “first direction from one end to the other end” means the direction in which the color is changing. For example, the first direction is preferably the direction in which the powders are laminated in the manufacturing method described below. For example, when the zirconia sintered body has a crown shape, the first direction is preferably a direction connecting the cut end side and the root side.

  The zirconia calcined body and composition of the present invention will be described. The zirconia calcined body and the composition of the present invention are the composition and the calcined body for producing the zirconia sintered body of the present invention, and the precursor (intermediate product) of the zirconia sintered body of the present invention described later and It will be. The calcined body is obtained by firing (ie, calcining) the composition at a temperature that does not result in sintering. Further, the calcined body includes a molded product. For example, a calcined body includes a dental prosthesis (for example, a crown shape) obtained by processing a calcined zirconia disk with a CAD / CAM (Computer-Aided Design / Computer-Aided Manufacturing) system.

  The composition and the calcined body of the present invention are produced by stacking zirconia powders having different compositions.

  The composition and the calcined body contain (mainly monoclinic) zirconia crystal particles, a stabilizer, and titanium oxide. The composition may contain aluminum oxide. The aluminum oxide is preferably alpha alumina.

  The average particle size of the zirconia powder (granular state) in the composition is preferably 20 μm to 40 μm.

Examples of the stabilizer in the composition and the calcined body include oxides such as calcium oxide (CaO), magnesium oxide (MgO), yttria, and cerium oxide (CeO ₂ ). The stabilizer is preferably added in an amount such that the zirconia particles in the sintered body can be partially stabilized. For example, when yttria is used as the stabilizer, the yttria content is preferably 2.5 mol% to 4.5 mol% with respect to the total mol number of zirconia and yttria, and 3 mol% to 4.5 mol%. Is preferable, and 3.5 mol% to 4.5 mol% is more preferable.

  The content of aluminum oxide in the composition and the calcined body is preferably 0% by mass (not containing) to 0.3% by mass based on the total mass of the zirconia crystal particles and the stabilizer. This is to increase the strength of the zirconia sintered body. If it is more than 0.3% by mass, the transparency of the zirconia sintered body will decrease.

  The content of titanium oxide in the composition and the calcined body is preferably 0% by mass (not containing) to 0.6% by mass based on the total mass of the zirconia crystal particles and the stabilizer. This is because grain growth of the zirconia crystal is performed. If it is more than 0.6% by mass, the strength of the zirconia sintered body will decrease.

In the composition and calcined body of the present invention, the content of silicon oxide is preferably 0.1% by mass or less based on the total mass of the zirconia crystal particles and the stabilizer, and the composition and calcined body are It is preferable that silicon oxide (SiO ₂ ; silica) is not substantially contained. If silicon oxide is contained, the transparency of the zirconia sintered body will decrease. The term "substantially free from" as used herein means that the property of the present invention does not particularly affect the characteristics, and preferably means that the content is not higher than the impurity level, and is not necessarily below the detection limit. It does not mean that there is.

The composition and the calcined body of the present invention may contain a pigment for coloring. For example, when the zirconia sintered body produced from the composition of the present invention and the calcined body is applied to a dental material, examples of the pigment include chromium oxide (Cr ₂ O ₃ ) and erbium oxide (Er ₂ O). ₃ ), iron oxide (Fe ₂ O ₃ ), praseodymium oxide (Pr ₆ O ₁₁ ), and the like can be used. These pigments may be used in combination. The pigment content can also be partially different.

  For example, in the molded composition and the calcined body, the whole is divided into four layers, and the region of 25% to 45% from the lower end to the total thickness is the first layer and the total thickness on the first layer. 5% to 25% of the area is the second layer, the second layer, the area of 5% to 25% of the total thickness of the third layer, and the third layer from the top to the top, When the region of 25% to 45% with respect to the entire thickness is the fourth layer, it is preferable that the content of the pigment decreases from the first layer to the fourth layer.

  For example, when a sintered body produced from the composition and the calcined body is used as a dental material, erbium oxide and iron oxide can be added as pigments. In this case, in the first layer, the content of erbium oxide is 0.33% by mass to 0.52% by mass and the content of iron oxide is 0.05% with respect to the total mass of zirconia and the stabilizer. It is preferable that it is from 0.1% by mass to 0.12% by mass. In the second layer, the content of erbium oxide is 0.26 mass% to 0.45 mass% and the content of iron oxide is 0.04 mass% to the total mass of zirconia and the stabilizer. It is preferably 0.11% by mass. In the third layer, the content of erbium oxide is 0.05 mass% to 0.24 mass% and the content of iron oxide is 0.012 mass% to the total mass of zirconia and the stabilizer. It is preferably 0.08% by mass. In the fourth layer, the content of erbium oxide is 0% by mass to 0.17% by mass and the content of iron oxide is 0% by mass to 0.07% by mass with respect to the total mass of zirconia and the stabilizer. % Is preferable. It is preferable that the content rates of erbium oxide and iron oxide gradually decrease from the first layer to the fourth layer.

  For example, when a sintered body produced from the composition and the calcined body is used as a dental material, erbium oxide, iron oxide and chromium oxide can be added as pigments. For example, when a sintered body produced from the composition and the calcined body is used as a dental material, the content of erbium oxide in the first layer is 0.1% with respect to the total mass of zirconia and the stabilizer. 08 mass% to 0.37 mass%, the content of iron oxide is 0.08 mass% to 0.15 mass%, and the content of chromium oxide is 0.0008 mass% to 0.0012 mass%. It is preferable to have. In the second layer, the content of erbium oxide is 0.06 mass% to 0.42 mass% and the content of iron oxide is 0.06 mass% to the total mass of zirconia and the stabilizer. It is preferably 0.18% by mass, and the chromium oxide content is preferably 0.0006% by mass to 0.001% by mass. In the third layer, the content of erbium oxide is 0.06 mass% to 0.17 mass% and the content of iron oxide is 0.018 mass% to the total mass of zirconia and the stabilizer. It is preferably 0.042% by mass and the chromium oxide content is 0.0001% by mass to 0.0003% by mass. In the fourth layer, the content of erbium oxide is 0% by mass to 0.12% by mass and the content of iron oxide is 0% by mass to 0.001% by mass with respect to the total mass of zirconia and the stabilizer. %, And the chromium oxide content is preferably 0% by mass to 0.0001% by mass. It is preferable that the content rates of erbium oxide, iron oxide, and chromium oxide gradually decrease from the first layer to the fourth layer.

  For example, when a sintered body produced from the composition and the calcined body is used as a dental material, erbium oxide, iron oxide and praseodymium oxide can be added as pigments. For example, when a sintered body produced from the composition and the calcined body is used as a dental material, the content of erbium oxide in the first layer is 0.1% with respect to the total mass of zirconia and the stabilizer. 08 mass% to 2.2 mass%, the content of iron oxide is 0.003 mass% to 0.12 mass%, and the content of praseodymium oxide is 0.003 mass% to 0.12 mass%. It is preferable to have. In the second layer, the content of erbium oxide is 0.06 mass% to 1.9 mass% and the content of iron oxide is 0.002 mass% to the total mass of zirconia and the stabilizer. It is 0.11 mass%, and the content rate of praseodymium oxide is preferably 0.002 mass% to 0.11 mass%. In the third layer, the content ratio of erbium oxide is 0.018% by mass to 1% by mass and the content ratio of iron oxide is 0.008% by mass to 0.1% with respect to the total mass of zirconia and the stabilizer. The content of praseodymium oxide is preferably 0.0008% by mass to 0.06% by mass. In the fourth layer, the content of erbium oxide is 0 mass% to 0.7 mass% and the content of iron oxide is 0 mass% to 0.05 mass with respect to the total mass of zirconia and the stabilizer. %, And the content of praseodymium oxide is preferably 0% by mass to 0.05% by mass. It is preferable that the content rates of erbium oxide, iron oxide and praseodymium oxide gradually decrease from the first layer to the fourth layer.

  The pigment content can be theoretically calculated from the amount of zirconia and the stabilizer added to the total mass and the production method.

  Regarding the calcined body of the present invention, the bending strength measured according to JIS R1601 is preferably 38 MPa or more, more preferably 40 MPa or more, and further preferably 42 MPa or more.

  In the case of the calcined body of the present invention, in the three-point bending test, the load point is located at the boundary portion between the layers when the zirconia powders having different compositions are laminated as shown in the manufacturing method described later. However, the above bending strength can be obtained. For example, when the bending strength is measured by the same test as the bending test of the sintered body described below, higher strength can be obtained as compared with a calcined body produced by simply stacking powders. Further, even if the bending strength is measured by a test in which a load is applied to the boundary, it is possible to obtain the same strength as that of a calcined body that is not laminated (no boundary). In the calcined body of the present invention, the bending strength measured by applying a load to the boundary between layers is the bending strength in a region other than the boundary (for example, from a composition which is not a laminate, the same condition (for example, the same calcining temperature and calcining). 90% or more, and more preferably 95% or more of the bending strength of the calcined body produced in (time).

  The composition and the calcined body of the present invention do not cause peeling at the boundary between layers formed by stacking zirconia powders having different compositions, even if heat treatment is performed for calcination or sintering, and It is possible to suppress even such deformation. 1 and 2 show schematic views of test pieces for measuring the amount of deformation during sintering. FIG. 1 is a schematic diagram of a two-layer laminate. FIG. 2 is a schematic diagram of a four-layer laminate. FIG. 3 shows a schematic diagram for explaining the method of measuring the deformation amount. For example, a plurality of zirconia powders having different compositions are laminated to form a composition, and the composition is fired at 800 ° C. to 1200 ° C. for 2 hours to produce a calcined body. Then, as shown in FIGS. 1 and 2, the calcined body is formed into a rectangular parallelepiped shape having dimensions of width 50 mm × height 10 mm × depth 5 mm by a CAD / CAM system. This is a test piece. For example, the test piece 20 of the two-layer laminated body shown in FIG. 1 has a first layer 21a and a second layer 21b. The thickness of the first layer 21a and the thickness of the second layer 21b are each 50% of the total thickness. The test piece 22 of the four-layer laminated body shown in FIG. 2 has a first layer 23a, a second layer 23b, a third layer 23c, and a fourth layer 23d. The thickness of each of the first layer 23a and the fourth layer 23d is 35% of the total thickness. The thickness of each of the second layer 23b and the third layer 23c is 15% of the total thickness. When the surface of the test pieces 20 and 22 of 50 mm × 5 mm is the bottom surface (top surface and bottom surface), each layer extends in the same direction as the bottom surfaces 20 a and 22 a, and preferably extends in parallel. That is, the boundary between layers is parallel to the bottom surfaces 20a and 22a. When this test piece is fired at 1500 ° C. for 2 hours and sintered, the bottom surfaces 20a and 22a are deformed so as to be curved. The test pieces 20 and 22 are placed on a flat surface (ground plane 30) with the concave side of the bottom surfaces 20a and 22a facing down. Then, the width of the test pieces 20 and 22 after deformation, that is, the distance L between the ground contact portions in the width direction is measured. Further, of the distances between the bottom surfaces 20a and 22a that have been deformed into a concave shape and the ground contact surface 30, the distance d of the largest portion is measured. Then, the deformation amount is calculated as (d / L × 100). This deformation amount is preferably 0.15 or less, more preferably 0.1 or less, more preferably 0.05 or less, and further preferably 0.03 or less.

  A composition and a calcined body produced by laminating zirconia powders having different compositions are easily deformed by sintering, but according to the composition and the calcined body of the present invention, a composition produced simply by laminating and The amount of deformation can be reduced as compared with the calcined body. As a result, the dimensional accuracy of the final product can be improved. For example, the composition and the calcined body of the present invention can be suitably applied to a dental prosthesis having a large individual difference. Note that, in FIG. 1 and FIG. 2, the upper and lower mixed layers, which are presumed to be formed at the boundary between the layers, are not shown for simplification.

  The composition of the present invention also includes a powder, a fluid obtained by adding the powder to a solvent, and a molded body obtained by molding the powder into a predetermined shape. That is, the composition may be in the form of powder, a paste or a wet composition (that is, it may be in a solvent or may contain a solvent). Further, the composition may contain additives such as a binder and a pigment. In calculating the content, the mass of the additive such as the solvent and the binder is not taken into consideration.

  When the composition of the present invention is a molded product, it may be molded by any molding method, and may be molded by, for example, press molding, injection molding or stereolithography, and has a multi-step structure. It may be molded. For example, the composition of the present invention may be press-molded and then further subjected to CIP (Cold Isostatic Pressing; cold isostatic pressing).

  The calcined body of the present invention can be obtained by firing the composition of the present invention at 800 ° C to 1200 ° C under normal pressure.

  The length (thickness) in the stacking direction of the composition and the calcined body is preferably determined in consideration of sintering shrinkage so as to achieve the target length of the sintered body. For example, when using a sintered body produced from the composition and the calcined body as a dental material, for example, the target length of the sintered body in the stacking direction is 5 mm to 18 mm, and the composition and the calcined body are used. The length (thickness) in the stacking direction can be set to 10 mm to 26 mm.

  Next, the zirconia sintered body of the present invention will be described. The zirconia sintered body of the present invention is a sintered body in which partially stabilized zirconia crystal particles are mainly sintered, and has partially stabilized zirconia as a matrix phase. In the zirconia sintered body of the present invention, the main crystal phase of zirconia is a tetragonal system or a tetragonal system and a cubic system. It is preferable that the zirconia sintered body does not substantially contain a monoclinic system (at a stage before the hydrothermal treatment test described below).

  The zirconia sintered body of the present invention includes not only a sintered body in which molded zirconia particles are sintered under normal pressure or non-pressurization, but also HIP (Hot Isostatic Pressing) treatment or the like. Also included are sintered bodies that have been densified by high-temperature pressure treatment.

The zirconia sintered body of the present invention contains zirconia and a stabilizer thereof. The stabilizer suppresses the phase transition of tetragonal zirconia to the monoclinic system. By suppressing the phase transition, strength, durability and dimensional accuracy can be improved. Examples of the stabilizer include oxides such as calcium oxide (CaO), magnesium oxide (MgO), yttrium oxide (Y ₂ O ₃ ) (hereinafter referred to as “yttria”), and cerium oxide (CeO ₂ ). Be done. The stabilizer is preferably added in an amount such that the tetragonal zirconia particles can be partially stabilized. For example, when yttria is used as the stabilizer, the yttria content is preferably 2.5 mol% to 5 mol% and preferably 3 mol% to 4.5 mol% with respect to the total mol number of zirconia and yttria. Is more preferable, and 3.5 mol% to 4.5 mol% is more preferable. If the content of the stabilizer is too high, the phase change can be suppressed, but the bending strength and the fracture toughness will decrease. On the other hand, if the content of the stabilizer is too low, the deterioration of bending strength and fracture toughness can be suppressed, but the suppression of the progress of phase transition is insufficient. The tetragonal zirconia partially stabilized by adding a stabilizer is called partially stabilized zirconia (PSZ).

The zirconia sintered body of the present invention preferably contains aluminum oxide (Al ₂ O ₃ ; alumina). The aluminum oxide is preferably alpha alumina. The strength can be increased by including aluminum oxide. The content of aluminum oxide in the zirconia sintered body is preferably 0% by mass (not containing) to 0.3% by mass with respect to the total mass of zirconia and the stabilizer. If the content of aluminum oxide is more than 0.3% by mass, the transparency will decrease.

The zirconia sintered body of the present invention preferably contains titanium oxide (TiO ₂ ; titania). The inclusion of titanium oxide can promote grain growth. The content of titanium oxide in the zirconia sintered body is preferably 0% by mass (not containing) to 0.6% by mass with respect to the total mass of zirconia and the stabilizer. If the content of titanium oxide is more than 0.6% by mass, the strength will be reduced.

In the zirconia sintered body of the present invention, the content of silicon oxide (SiO ₂ ; silica) is preferably 0.1% by mass or less based on the total mass of zirconia and the stabilizer, and the zirconia sintered body is It is preferable that silicon oxide is not substantially contained. If silicon oxide is contained, the transparency of the zirconia sintered body will decrease. The term "substantially free from" as used herein means that the property of the present invention does not particularly affect the characteristics, and preferably means that the content is not higher than the impurity level, and is not necessarily below the detection limit. It does not mean that there is.

The zirconia sintered body of the present invention may contain a pigment for coloring. When the zirconia sintered body is applied to a dental material, examples of the pigment include chromium oxide (Cr ₂ O ₃ ), erbium oxide (Er ₂ O ₃ ), iron oxide (Fe ₂ O ₃ ), praseodymium oxide (Pr). ₆ O ₁₁ ) and the like can be used. These pigments may be used in combination. The pigment content can be partially different.

  For example, when the zirconia sintered body used as a dental material contains chromium oxide, the partial content ratio of chromium oxide in the region containing chromium oxide is 0. It is preferably 001% by mass or less. When the zirconia sintered body used as a dental material contains erbium oxide, the partial content of erbium oxide in the region containing erbium oxide is 2% by mass or less based on the total mass of zirconia and the stabilizer. Is preferred. For example, when the zirconia sintered body used as a dental material contains iron oxide, the partial content of iron oxide in the iron oxide-containing region is 0. It is preferably 1% by mass or less. For example, when the zirconia sintered body used as a dental material contains praseodymium oxide, the partial content of praseodymium oxide in the region containing praseodymium oxide is 0. It is preferably 1% by mass or less.

  After the sintering of the zirconia sintered body, a hydrothermal treatment test which is a deterioration acceleration test (described later) in the X-ray diffraction pattern of the unprocessed zirconia sintered body measured by CuKα line, 2θ is around 30 ° It exists near the position where the [11-1] peak derived from the monoclinic crystal with 2θ of 28 ° is around the height of the peak (hereinafter referred to as “first peak”) existing near the position where the [111] peak occurs. The height ratio of peaks (hereinafter referred to as “second peak”) (that is, “height of second peak / height of first peak”; hereinafter referred to as “monoclinic peak ratio”) is 0.1. It is preferably below, and more preferably 0.05 or below.

  In the zirconia sintered body of the present invention, the progress of the phase transition from the tetragonal system to the monoclinic system is suppressed even when subjected to the hydrothermal treatment test. For example, when hydrothermal treatment is performed at 180 ° C. and 1 MPa for 5 hours on the zirconia sintered body of the present invention, the monoclinic crystal is observed in the X-ray diffraction pattern measured by CuKα line on the surface of the zirconia sintered body after hydrothermal treatment. The peak ratio is preferably 1 or less, more preferably 0.8 or less, still more preferably 0.7 or less, and further preferably 0.6 or less.

  In this document, the “hydrothermal treatment test” refers to a test based on ISO13356. However, the condition specified in ISO13356 is “134 ° C., 0.2 MPa, 5 hours”. , The test time is set appropriately according to the purpose. The hydrothermal treatment test is also called a "low temperature deterioration accelerated test" or a "hydrothermal deterioration test".

  The bending strength of the zirconia sintered body of the present invention measured according to JIS R1601 is preferably 1000 MPa or more, more preferably 1100 MPa or more, and even more preferably 1200 MPa or more. In addition, these are the numerical values of the state not subjected to the hydrothermal treatment test.

  In the zirconia sintered body of the present invention, in the three-point bending test, the above bending strength can be obtained even when the load point is located at the boundary portion between layers in the manufacturing method described later. FIG. 4 shows a schematic diagram of the three-point bending test. For example, in the test piece, the boundary when zirconia powders having different compositions are laminated is located at the center (the center in the longitudinal direction) of the test piece. The boundary extends along the load application direction (along the direction of the smallest area) and crosses the test piece. The load point of the three-point bending test is aligned with the position of the boundary. Thus, even if the bending strength is measured by a test in which a load is applied to the boundary, it is possible to obtain the same strength as that of a non-laminated (no boundary) sintered body. For example, in the sintered body of the present invention, the bending strength measured by applying a load to the boundary between layers is the bending strength in a region other than the boundary (for example, from a composition that is not a laminate, the same condition (for example, the same calcination temperature 90% or more, and more preferably 95% or more of the bending strength of the calcined body produced in (calcination time).

For zirconia sintered body of the present invention, fracture toughness was measured according to JISR1607 is preferable to be 3.5 MPa ^{· m 1/2} or more, more preferably 3.8 MPa ^{· m 1/2} or more, 4 MPa · m ^1/2 or more is more preferable, and 4.2 MPa · m ^1/2 or more is more preferable. In addition, these are the numerical values of the state not subjected to the hydrothermal treatment test.

  In the zirconia sintered body of the present invention, in the fracture toughness measurement test, the above fracture toughness can be obtained even when the load point is located at the boundary portion between layers in the manufacturing method described later. For example, in the test piece, the boundary when zirconia powders having different compositions are laminated is located at the center (the center in the longitudinal direction) of the test piece. The boundary extends along the load application direction (along the direction of the smallest area) and crosses the test piece. The position of the diamond indenter in the measurement test is aligned with the boundary. Thus, even if the fracture toughness is measured by a test in which a load is applied to the boundary, it is possible to obtain the same fracture toughness as a non-laminated (no boundary) sintered body.

It is preferable that the zirconia sintered body of the present invention satisfies the above numerical values with respect to the peak ratio of the monoclinic crystal after hydrothermal treatment, bending strength and fracture toughness. For example, the zirconia sintered body of the present invention has a monoclinic crystal peak ratio after hydrothermal treatment of 1 or less, a fracture toughness of 3.5 MPa · m ^1/2 or more, and a bending strength of 1000 MPa or more. preferable. More preferably, the zirconia sintered body of the present invention has a monoclinic crystal peak ratio after hydrothermal treatment of 0.6 or less, fracture toughness of 4 MPa · m ^1/2 or more, and bending strength of 1000 MPa or more. is there.

When the zirconia sintered body of the present invention is colored, particularly when the color gradually changes in one direction (becomes a gradation), the zirconia sintered body of the present invention has a color It is preferable that there exists a direction in which is not substantially changed. FIG. 5 shows a schematic diagram of the zirconia sintered body. For example, in the zirconia sintered body 10 shown in FIG. 5, it is preferable that the color does not substantially change in the first direction X. For example, between two arbitrary points on a straight line extending in the first direction X, the difference between the L ^* value, the a ^* value, and the b ^* value, which are the chromaticities in the L ^* a ^* b ^* color system (JISZ8729). the [Delta] L ^*, respectively, and .DELTA.a ^* and [Delta] b ^*, when calculating the Delta] E ^* ab of the following formula, preferably a Delta] E ^* ab is less than 1, more preferably less than 0.5.

Formula 2

Further, when the zirconia sintered body of the present invention is colored, it is preferable that the color changes (has a gradation) from one end connecting both ends to the other end. On the straight line extending from the one end P to the other end Q of the zirconia sintered body 10 shown in FIG. 5 in the second direction Y, the increasing or decreasing tendency of the L ^* value, the a ^* value and the b ^* value is in the opposite direction. It is preferable not to change to. That is, if the L ^* value on a straight line toward the other Q from one end P is increasing, the L ^* value is not substantially reduced interval exists preferred. For example, if the L ^* value on a straight line toward the other Q from one end P is increasing, preferably the L ^* value is no section to reduce one or more, if there is no section that decreases 0.5 or more preferable. When the a ^* value tends to decrease on the straight line from the one end P to the other end Q, it is preferable that there is no section in which the a ^* value substantially increases. For example, if the a ^* value on a straight line toward the other Q from one P is decreasing, preferably when there is no section where the a ^* value increases by one or more, if there is no section to increase 0.5 or more preferable. When the b ^* value tends to decrease on the straight line extending from the one end P to the other end Q, it is preferable that there is no section in which the b ^* value substantially increases. For example, if the b ^* value is decreasing on a straight line toward the other Q from one end P, preferably the b ^* value does not exist interval increase of 1 or more, the absence of section to be increased by 0.5 or more and more preferable.

The direction of color change in the zirconia sintered body 10 is preferably that when the L ^* value tends to increase from the one end P to the other end Q, the a ^* value and the b ^* value tend to decrease. For example, when the zirconia sintered body 10 is used as a dental prosthesis material, it is preferable that the direction from one end P to the other end Q changes from light yellow, light orange or light brown to white.

  In FIG. 5, points on a straight line connecting one end P to the other end Q are a first point A, a second point B, a third point C, and a fourth point D in order from the one end P side. When the zirconia sintered body 10 is used as a dental prosthesis material, the first point A is from 25% to 45% of the length between one end P and the other end Q (hereinafter referred to as "total length"). It is preferable to be in the section. The second point B is preferably in a section from 30% of the total length from one end P to 70% of the total length from one end P. The fourth point D is preferably in the section from the other end Q to 25% to 45% of the total length. The third point C is preferably located in a section from the other end Q 30% of the entire length to 70% of the total length from the other end Q.

Chromaticity (L ^* , a ^* , b ^* ) of the zirconia sintered body 10 according to the L ^* a ^* b ^* color system (JISZ8729) at the first point A, the second point B, the third point C, and the fourth point D. ) Is (L1, a1, b1), (L2, a2, b2), (L3, a3, b3) and (L4, a4, b4). At this time, it is preferable that the following magnitude relationship be established. The chromaticity at each point can be determined by producing a zirconia sintered body of the composition alone corresponding to each point and measuring the chromaticity of the zirconia sintered body.

L1 <L2 <L3 <L4
a1>a2>a3> a4
b1>b2>b3> b4

  When the zirconia sintered body of the present invention is applied to a dental material, for example, L1 is preferably 58.0 or more and 76.0 or less. L2 is preferably 62.5 or more and 80.5 or less. L3 is preferably 69.1 or more and 82.3 or less. L4 is preferably 71.8 or more and 84.2 or less.

  When the zirconia sintered body of the present invention is applied to a dental material, for example, a1 is preferably −1.6 or more and 7.6 or less. a2 is preferably -1.8 or more and 5.5 or less. a3 is preferably −2.1 or more and 1.6 or less. a4 is preferably −2.1 or more and 1.8 or less.

  When the zirconia sintered body of the present invention is applied to a dental material, for example, b1 is preferably 5.5 or more and 26.7 or less. b2 is preferably 4.8 or more and 21.8 or less. b3 is preferably 3.5 or more and 16.2 or less. b4 is preferably 1.9 or more and 16.0 or less.

  When the zirconia sintered body of the present invention is applied to a dental material, L1 is preferably 60.9 or more and 72.5 or less, a1 is 0.2 or more and 5.9 or less, and b1 is 11.5. Or more and 24.9 or less, L4 is 72.2 or more and 79.2 or less, a4 is -1.2 or more and 1.7 or less, and b4 is 6.0 or more and 15.8 or less. More preferably, L1 is 63.8 or more and 68.9 or less, a1 is 2.0 or more and 4.1 or less, b1 is 17.5 or more and 23.4 or less, and L4 is 72.5 or more 74. 0.1 or less, a4 is −0.2 or more and 1.6 or less, and b4 is 10.1 or more and 15.6 or less. This makes it possible to match the average tooth color.

The color difference ΔE ^* ab between two adjacent points can be expressed by the following formula. ΔL ^* is a difference (for example, L1-L2) between L ^* values in two adjacent layers. Δa ^* is a difference between a ^* values in two adjacent layers (for example, a1-a2). Δb ^* is the difference between the b ^* values in two adjacent layers (for example, b1-b2). The color difference between the first point A and the second point B is ΔE ^* ab1, the color difference between the second point B and the third point C is ΔE ^* ab2, and the color difference between the third point C and the fourth point D is ΔE ^* ab3. At this time, when the chromaticities of the first point A, the second point B, the third point C, and the fourth point D have the above relationship, for example, ΔE ^* ab1 is preferably 3.7 or more and 14.3 or less. ΔE ^* ab2 is preferably 1.8 or more and 17.9 or less. ΔE ^* ab3 is preferably 1.0 or more and 9.0 or less. This makes it possible to reproduce the same color change as natural teeth.

Formula 3

When the color difference between the first point A and the fourth point D is ΔE ^* ab4, and the chromaticity of the first point A, the second point B, the third point C, and the fourth point D has the above relationship, for example, ΔE ^* ab4 is preferably 36 or less. Color difference Delta] E ^* ab1 the first point A and the second point B, and the sum of the color difference Delta] E ^* ab2 and the three points C and a fourth point color difference Delta] E ^* ab3 of the second point B and the third point C, the first point The value obtained by subtracting the color difference ΔE ^* ab4 between A and the fourth point D is preferably 1 or less. This makes it possible to show a natural color change.

In the zirconia sintered body of the present invention, on a straight line so as to traverse layers (when they intersect the boundary) when powders having different compositions are laminated in the manufacturing method described later, that is, in the second direction Y shown in FIG. A continuous change in the b ^* value of the L ^* a ^* b ^* color system (JISZ8729) along the line was measured, and the b ^* value did not become constant even across the layers, and the gradual increase tendency (or decrease) was observed. It is preferable to show a tendency). Further, it is preferable that no sudden increase / decrease in the b ^* value is observed even when crossing the boundary portion. This change in the b ^* value can be measured using, for example, a two-dimensional colorimeter RC-300 manufactured by Paparabo Co., Ltd. In this measurement, the interval between adjacent measurement points can be set to 13 μm, for example.

  When the zirconia sintered body of the present invention is applied to a dental material, and the chromaticity at the fourth point D is within the above range, a zirconia sintered body is prepared from the composition corresponding to the fourth point alone, and both surfaces are prepared. The light transmittance measured according to JIS K7361 after producing a mirror-finished sample having a thickness of 0.5 mm is preferably 27% or more. When the chromaticity at the first point A is in the above range, a zirconia sintered body is prepared by using the composition corresponding to the first point alone, and both surfaces are mirror-polished to prepare a 0.5 mm thick sample. The light transmittance measured according to JIS K7361 is preferably 10% or more.

  When the zirconia sintered body of the present invention is applied to a dental material, the length L in the first direction Y of the zirconia sintered body 10 of the present invention preferably satisfies at least the length corresponding to the exposed portion of the natural tooth. .. For example, the length L of the zirconia sintered body 10 is preferably 5 mm to 18 mm.

  The sintered body of the present invention can be produced by firing the calcined body or composition of the present invention at 1350 ° C to 1600 ° C under normal pressure.

  Next, an example of a method for producing the composition, the calcined body and the sintered body of the present invention will be described. Here, a method for gradually changing (grading) the color of the sintered body will also be described.

  First, zirconia and a stabilizer are wet mixed in water to form a slurry. Next, the slurry is dried and granulated. Next, the granulated material is calcined to produce a primary powder.

  Next, when gradation is applied to the sintered body, the primary powder is divided into two. Next, the pigment is added to at least one of the two primary powders so that the addition rate of the pigment is different. For example, the pigment may not be added to one side and the pigment may be added to the other side. Hereinafter, the powder having a lower addition rate of the specific pigment is referred to as a low-addition rate powder, and the secondary powder having a higher addition rate of the specific pigment is referred to as a high-addition rate powder. The addition amount of the pigment in the high addition rate powder is preferably adjusted to the addition amount of the darkest region of the sintered body. Then, for each of them, zirconia is pulverized and mixed in water until a desired particle size is obtained, to form a zirconia slurry. Next, the slurry is dried and granulated to produce a secondary powder. When an additive such as aluminum oxide, titanium oxide or a binder is added, it may be added at the time of producing the primary powder or may be added at the time of producing the secondary powder.

  Next, a plurality of powders having different pigment content ratios are prepared based on the secondary powders of the low addition ratio powder and the high addition ratio powder. For example, in the case of producing the above-mentioned composition and calcined body having a total of four layers, the first powder for the first layer is made to have a high addition rate powder of 100% without mixing the low addition rate powder. The second powder for the second layer is mixed at a low addition rate powder: high addition rate powder = 5: 95 to 15:85 ratio. The third powder for the third layer is mixed at a low addition rate powder: high addition rate powder = 35: 65 to 45:55 ratio. The fourth powder for the fourth layer is mixed at a low addition rate powder: high addition rate powder = 45: 55 to 55:45 ratio. As another mixing ratio, for example, in the case of producing a composition and a calcined body of a total of four layers described above, the first powder for the first layer is a high addition rate powder 100 without mixing the low addition rate powder. %. The second powder for the second layer is mixed at a low addition rate powder: high addition rate powder = 10: 90 to 30:70 ratio. The third powder for the third layer is mixed at a low addition rate powder: high addition rate powder = 70: 30 to 90:10 ratio. The fourth powder for the fourth layer is 100% of the low addition rate powder without mixing the high addition rate powder.

  When the zirconia sintered body is used as a dental material, it is preferable that the compounding difference between the second layer and the third layer is larger than the compounding difference between the first layer and the second layer and the compounding difference between the third layer and the fourth layer. This makes it possible to reproduce the same color change as natural teeth.

  In this way, by adjusting the pigment content of each layer based on the two types of powders whose sintered bodies have different colors, the colors can be changed naturally when the powders are laminated in order (gradation is Can be produced).

  When the layers are laminated for purposes other than coloring, the number of layers in which the secondary powder is laminated is divided. A desired additive may be added to each powder.

  Next, a plurality of powders having different pigment contents are sequentially laminated. When forming a gradation on a sintered body, it is preferable to stack the layers in such a manner that the addition rate of a certain specific pigment becomes higher or lower stepwise in the order of stacking. First, after filling the mold with the powder of the first layer, the upper surface of the powder of the first layer is flattened. As a method for leveling the surface flat, for example, a method of vibrating a mold or scraping the upper surface of the powder of the first layer can be adopted. However, it is preferable that the press treatment is not performed until all the layers are laminated. Next, the powder of the second layer is filled on the powder of the first layer. Next, the mold is vibrated. Allow vibrations to be transmitted to the powder in the mold. As a method of applying vibration, for example, mechanical vibration may be applied to the mold, the mold may be manually shaken, or the mold may be hit with a metal punch or the like, and a desired method may be appropriately adopted. As a result, it is considered that the powder of the first layer and the powder of the second layer are partially mixed at the boundary between the powder of the first layer and the powder of the second layer. That is, the number and strength of vibrations, the frequency and amplitude in the case of mechanical vibration, the particle size, particle size distribution, particle shape, etc. of the powders so that the powders in the upper and lower layers are mixed at the boundary between layers. It can be appropriately set according to. Next, the upper surface of the powder of the second layer is smoothed in the same manner as the powder of the first layer. This operation is repeated until all layers are laminated.

  For example, in the case of producing the above-mentioned composition and calcined body having a total of four layers, the mold is filled with the first powder to a predetermined thickness (for example, 25% to 45% of the total thickness). At this time, the upper surface of the first powder is flattened, but the pressing process is not performed. Next, the second powder is filled on the first powder to a predetermined thickness (for example, 5% to 25% of the total thickness). Next, the mold is vibrated. It is presumed that this vibration forms a first boundary layer in which the first powder and the second powder are mixed at the boundary between the upper surface of the first powder and the lower surface of the second powder. Next, the upper surface of the second powder is flattened. The second powder is not subjected to a press treatment before the third powder is filled. Next, the third powder is filled on the second powder to a predetermined thickness (for example, 5% to 25% of the total thickness). Next, the mold is vibrated. It is speculated that this vibration forms a second boundary layer in which the second powder and the third powder are mixed at the boundary between the upper surface of the second powder and the lower surface of the third powder. Next, the upper surface of the third powder is flattened. The third powder is not pressed before the fourth powder is filled. Next, the fourth powder is filled on the third powder to a predetermined thickness (for example, 25% to 45% of the total thickness). Next, the mold is vibrated. It is estimated that this vibration forms a third boundary layer in which the third powder and the fourth powder are mixed at the boundary between the upper surface of the third powder and the lower surface of the fourth powder.

  When all layers are laminated, press molding is performed to produce a molded product as the composition of the present invention. The molded product may be further subjected to CIP treatment.

  It is possible to form a boundary layer in which the powders of the upper and lower layers are mixed between the adjacent layers by not performing the pressing process before filling the powder of the next layer and by giving vibration every time each layer is filled. Conceivable. Thereby, in the sintered body, the adhesion between the adjacent layers can be enhanced. Shrinkage amount or shrinkage rate during heat treatment can be made equal for each layer, preventing peeling between layers during heat treatment and preventing the sintered body from deforming into a target shape. can do. Furthermore, the color difference between adjacent layers can be reduced. This allows the color of the sintered body to change naturally in the stacking direction (a gradation can be created).

  Also, this method does not require an intermediate layer between each major layer. That is, when four main layers are stacked, only four layers need to be stacked. Also, no pressing process is required for each layer. As a result, the labor and time can be greatly reduced, and the manufacturing cost can be reduced.

  When the calcined body is not produced, the composition is fired at 1400 ° C to 1600 ° C, preferably 1450 ° C to 1550 ° C to sinter the zirconia powder and produce the zirconia sintered body of the present invention. .. It may be molded into a desired shape at the stage of the molded product.

  When producing a calcined body, the composition is fired at 800 ° C to 1200 ° C to produce a calcined body. Next, the calcined body is fired at 1400 ° C to 1600 ° C, preferably 1450 ° C to 1550 ° C to sinter the zirconia powder and produce the zirconia sintered body of the present invention. The forming may be performed by cutting or the like at the stage of the calcined body, or may be performed after sintering. Molding can be performed with a CAD / CAM system.

  The method for producing a dental prosthesis is the same as the method for producing a sintered body, except that the calcined body or the sintered body is formed into a crown shape.

  In addition, in the said embodiment, although the composition based on the laminated body of 4 layers, the calcined body, and the sintered body were illustrated, it is not limited to 4 layers. For example, it may be a composition, a calcined body, or a sintered body prepared from the above-mentioned two-layer laminate of the first layer and the fourth layer. Alternatively, a composition, a calcined body, and a sintered body prepared from a laminate of the above-mentioned first layer, second layer and fourth layer, or three layers of the first layer, third layer and fourth layer. May be. Further, FIG. 4 is for facilitating the description of the positional relationship and direction of each point, and the shape and dimensions are not limited to the form shown in FIG.

[Examples 1 to 4]
[Production of composition, calcined body and sintered body]
A sintered body was prepared based on the composition prepared by laminating zirconia powders having different compositions, and the bending strength, chromaticity, and deformation amount were measured.

  First, zirconia powder containing a stabilizer was prepared. To 92.8% by mass of mainly monoclinic zirconia powder, 7.2% by mass (4 mol%) of yttria was added as a stabilizer. To the mixed powder of zirconia and yttria (100% by mass), alumina sol was added so that 0.1% by mass of alumina was added, and further 150% by mass of water was added to the mixed powder of zirconia and yttria (100% by mass). , 0.2% by mass of a defoaming agent, and 1% by mass of a dispersant were added, and the mixture was pulverized with a ball mill for 10 hours. The average particle size of the slurry formed after pulverization was 0.12 μm. Next, granulation was performed with a spray dryer, and the resulting granules were calcined at 1000 ° C. for 2 hours to prepare primary powders.

  Next, the primary powder was divided into two and the pigment was added to at least one. The powder with the lower addition rate of the pigment was defined as the low addition rate powder, and the one with the higher addition rate of the pigment was defined as the high addition rate powder. Table 1 shows the addition rates of Examples 1 to 3. Table 4 shows the addition rates of Example 4. The numerical values shown in Tables 1 and 2 are the addition rates to the mixed powder of zirconia and yttria (100% by mass). Further, to each powder, 0.2% by mass of titania, 200% by mass of water, 0.2% by mass of defoaming agent, and 1% by mass of dispersant were added to the mixed powder of zirconia and yttria (100% by mass). Then, this mixture was pulverized by a ball mill for 15 hours. The average particle size of the slurry formed after pulverization was 0.13 μm. Next, 6% by mass of the binder and 0.5% by mass of the release agent were added and mixed by a ball mill for 15 minutes. Next, the resulting slurry was granulated with a spray dryer to prepare a low addition rate powder and a high addition rate powder secondary powder.

  Next, the low addition rate powder and the high addition rate powder were mixed in the ratios shown in Tables 3 to 6 to prepare first to fourth powders.

Next, a molded body was produced. In Examples 1, 3 and 4, a mold having an inner size of 82 mm × 25 mm was filled with 35 g of the first powder, and the upper surface was scraped to flatten the upper surface of the first powder. Next, 15 g of the second powder was filled on the first powder, and the mold was vibrated by a vibrating device. Then, the upper surface of the second powder was scraped off to flatten the upper surface of the second powder. Next, 15 g of the third powder was filled on the second powder, and the vibrating device vibrated the mold. Then, the upper surface of the third powder was scraped off to flatten the upper surface of the third powder. Next, 35 g of the fourth powder was filled on the third powder, and the mold was vibrated by a vibrating device. Then, the upper surface of the fourth powder was scraped off to flatten the upper surface of the fourth powder. Example 2 is the same as Examples 1, 3 and 4 except that 50 g of the first powder and 50 g of the second powder were filled. Next, the upper die was set, and primary press molding was performed for 90 seconds at a surface pressure of 200 kg / cm ² with a uniaxial press molding machine. Next, the primary press-molded body was CIP-molded at 1500 kg / cm ² for 5 minutes to prepare a molded body.

  Next, the molded body was fired at 1000 ° C. for 2 hours to prepare a calcined body. Next, a CAD / CAM system (Katana system, manufactured by Kuraray Noritake Dental Co., Ltd.) was used to form a crown shape. Next, the calcined body was fired at 1500 ° C. for 2 hours to produce a sintered body. The length of the sintered body in the stacking direction of the first to fourth powders was 17 mm.

  In each of the sintered bodies of Examples 1 to 4, a gradation that changes from pale yellow to yellowish white is formed from the region corresponding to the first layer of the composition toward the region corresponding to the fourth layer, It had the same appearance as teeth.

[Measurement of bending strength]
The bending strength of the calcined body and the sintered body produced in Example 4 was measured according to JIS R1601. As a comparative example, the bending strength was also measured for the calcined body and the sintered body, which were not vibrated when filling each powder. Comparative Example 1 is a calcined body and a sintered body produced from a composition that is not subjected to a press treatment each time each layer is filled. Comparative Example 2 is a calcined body and a sintered body produced from a composition that is pressed each time each layer is filled. The bending strength was measured according to JISR1601. However, the test piece was obtained by cutting out the longitudinal direction along the laminating direction. The portion of the test piece corresponding to the boundary (mixed layer) between the powders extends along the load application direction (along the smallest area direction) and crosses the test piece. Table 7 shows the results of measuring the bending strength by matching the load point of the three-point bending test to the position of the portion of the test piece corresponding to the mixed layer between the second powder and the third powder.

  Regarding the calcined body, the bending strength of Example 4 was 40 MPa or more, but the bending strength of Comparative Example was 36 MPa or less. From this, it is understood that by applying vibration during powder lamination, the bonding strength between layers can be increased in the stage of the calcined body. Regarding the sintered body, in Example 4, it was 1200 MPa or more, but in Comparative Examples 1 and 2, it was less than 1100 MPa, which was 100 MPa or more and lower than that of Example 4. It can be seen that the bonding strength between layers can be similarly increased in the sintered body as well.

  Further, as shown in Example 9 to be described later, the bending strength of Example 4 was the same as the bending strength of the sintered body produced without lamination in both the sintered body and the calcined body, and It can be seen that the decrease in bonding strength is not caused. From this, it is understood that, by applying vibration during powder lamination, the boundary between the laminated bodies has the same strength as the area other than the boundary in both the sintered body and the calcined body.

  It is considered that this is because the powders in the upper and lower layers were partially mixed at the boundary by vibrating when the powders in the respective layers were laminated to increase the bonding strength between the layers. In addition, secondarily, since the first to fourth powders were produced by mixing two kinds of powders, it is presumed that the difference in properties between the powders became small and it was easy to get used to.

[Measurement of fracture toughness]
The fracture toughness of the sintered body produced in Example 4 was measured according to JIS R1607. The position of the boundary in the test piece is the same as in the bending test described above. The presser is aligned with the position of the boundary between the second powder and the third powder. As a result, the fracture toughness was also 4.3 MPa · m ^1/2 . As shown in Example 9 described later, this numerical value is similar to the fracture toughness of the sintered body produced without lamination, and it can be seen that the reduction in fracture toughness is not caused by lamination.

[Measurement of shrinkage deformation during sintering]
In Example 4, with the calcined body prepared by calcination at 1000 ° C. for 2 hours, the test piece shown in FIGS. 1 and 2 was prepared, and the test piece was fired at 1500 ° C. for 2 hours to be deformed. The amount (d / L × 100) was measured. The measuring method of the amount of deformation was the same as the above-mentioned measuring method. Further, as a comparative example, similar to the bending test, the same test pieces were prepared for Comparative Example 1 and Comparative Example 2 and the amount of deformation after sintering was measured. Table 8 shows the measurement results.

  In each of the comparative examples, the deformation amount was 0.15 or more. On the other hand, in Example 4, the amount of deformation can be set to 0.05 or less, and it can be seen that the amount of deformation can be greatly suppressed as compared with the comparative example. From this, it is considered that shrinkage deformation at the time of sintering can be suppressed by applying vibration to the composition when laminating powders having different compositions.

  Further, comparing Comparative Example 1 and Comparative Example 2, the deformation amount of Comparative Example 1 is smaller. From this, it is considered that shrinkage deformation at the time of sintering can be further suppressed by not performing the press treatment after filling each layer.

  Furthermore, comparing the two-layer laminate and the four-layer laminate, the deformation amount of the four-layer laminate is smaller than that of the two-layer laminate. From this, it is considered that shrinkage deformation can be suppressed more by increasing the number of layers.

[Measurement of chromaticity and color difference]
With respect to the first powder, the second powder, the third powder, and the fourth powder in Examples 1 to 4, individual sintered bodies were prepared, and the chromaticity of the L ^* a ^* b ^* color system was measured. .. The chromaticity was measured by using a measuring device CE100-DC / US manufactured by Olympus Corporation after processing the sintered body into a disk having a diameter of 14 mm and a thickness of 1.2 mm, polishing both surfaces thereof. Further, based on the measurement result of chromaticity, the color difference ΔE ^* ab1 to ₃ between adjacent layers was calculated. Further, the color difference ΔE ^* ab ₄ between the first layer and the fourth layer was calculated. Then, it was calculated _{^{(ΔE * ab 1 + ΔE *}} ab 2 + ΔE * ab 3) -ΔE * ab 4. Tables 9 to 12 show the chromaticity. Table 13 shows the color difference.

  The chromaticity of the sintered body of each powder is considered to represent the chromaticity of the color partially exhibited by the zirconia sintered body.

In the first layer sintered body of the four-layer laminate, L ^* was 58 to 73, a ^* was 0 to 8 and b ^* was 14 to 27. In the sintered body of the second layer, L ^* was 64-73, a ^* was 0-6, and b ^* was 16-22. In the sintered body of the third layer, L ^* was 70 to 78, a ^* was -2 to 2, and b ^* was 5 to 17. In the sintered body of the fourth layer, L ^* was 72 to 84, a ^* was 2-1 and b ^* was 4 to 15.

  The color difference between the first layer sintered body and the second layer sintered body was 7-14. The color difference between the second layer sintered body and the third layer sintered body was 10-18. The color difference between the third layer sintered body and the fourth layer sintered body was 4 to 9. The color difference between the first layer sintered body and the fourth layer sintered body was 28 to 36. Color difference between first layer sintered body and second layer sintered body, color difference between second layer sintered body and third layer sintered body, and third layer sintered body and fourth layer sintered body The value obtained by subtracting the color difference between the first layer sintered body and the fourth layer sintered body from the total body color difference was 1 or less.

[Example 5]
[Measurement of change in b ^* value]
With respect to a mixed powder of zirconia and yttria (100% by mass), a low addition rate powder and a high addition rate powder in which a pigment was added at an addition rate shown in Table 14 were prepared, and a composition was prepared in a blending ratio shown in Table 15. Then, a sintered body was produced in the same manner as in Examples 1 to 4, and along the stacking direction (along the second direction Y in FIG. 1), the L ^* a ^* b ^* color system b ^* value The change was measured. FIG. 6 shows a schematic diagram of the manufactured test piece and measurement results. The upper diagram of FIG. 6 is a schematic view of the test piece, and shows dimensions and measurement directions. The lower part of FIG. 6 is a graph showing the measurement results. The test piece after sintering was prepared so as to have dimensions of 20 mm × 20 mm × 1 mm after sintering. The first layer is a region filled with the first powder, and the fourth layer is a region filled with the fourth powder. The b ^* value was measured by using a two-dimensional colorimeter RC-300 manufactured by Paparabo Co., placing a test piece at the center of a 29 mm × 22 mm size image, and scanning in the direction perpendicular to the boundary surface of each layer. , About 13 μm intervals. The numerical value on the X-axis of the graph in the lower diagram of FIG. 6 indicates the number of measurement points. As Comparative Example 3, a change in b ^* value was similarly measured for a sintered body produced by applying a pressing process each time each layer was filled without applying vibration when laminating the powder of each layer. The composition and blending ratio of the low addition rate powder and the high addition rate powder in Comparative Example 3 are the same as in Example 5. FIG. 7 shows a schematic diagram of the test piece and measurement results.

From the graph of FIG. 7, it can be seen that the b ^* value tends to be flat in the central portion of each layer. At the boundary between the layers, abrupt change in the b ^* value in the form of steps is also seen. It is considered that this is because the powders of the layers having different pigment compositions are independently sintered. According to this, in the appearance of the test piece of Comparative Example 3, a clean gradation is not formed. On the other hand, looking at the graph of FIG. 6, the b ^* value tends to increase gradually even in the central portion of each layer. At the boundary between the layers, no step-like change in the b ^* value is found, and it is difficult to determine where the boundary is. In particular, the transition is linear at the boundary between the first layer and the second layer and the boundary between the third layer and the fourth layer. According to this, it is understood that a beautiful gradation is formed on the appearance of the sintered body of the present invention. According to the present invention, in the present invention, by vibrating at the time of filling the first to fourth powders, the powders are mixed between the adjacent layers in the vicinity of the boundary between the upper and lower layers, and the difference in the pigment content ratio between the adjacent layers is caused. It is thought that this is due to the smaller size. Since the difference in pigment content between the second powder and the third powder is large, it is considered that the change in b ^* value in the graph also changes more rapidly than in other parts.

[Examples 6 to 15]
Based on the composition produced by laminating zirconia powders having different pigment compositions, a sintered body to be a dental prosthesis was produced. Further, the chromaticity of the sintered body of each powder, which was the basis of each layer, was measured. Furthermore, regarding the sintered body according to Example 9, the bending strength, fracture toughness, and peak ratio of monoclinic crystals after hydrothermal treatment were measured.

  First, a primary powder was prepared in the same manner as in Examples 1 to 4. Next, the primary powder was divided into four. Let each powder be the 1st-4th powder. In Examples 6 to 15, the pigments shown in Tables 6 to 16 below were added to each powder. The numerical values shown in the table are the addition rates to the mixed powder of zirconia and yttria (100% by mass). Then, secondary powders of the first to fourth powders were produced in the same manner as in Examples 1 to 4 except that the low addition rate powder and the high addition rate powder were not produced, and the addition rate of the pigment was not produced.

  Next, a molded body was produced in the same manner as in Examples 1 to 4. Next, the molded body was fired at 1000 ° C. for 2 hours to prepare a calcined body. Next, a CAD / CAM system (Katana system, manufactured by Kuraray Noritake Dental Co., Ltd.) was used to form a crown shape. Next, the calcined body was fired at 1500 ° C. for 2 hours to produce a sintered body. The length of the sintered body in the stacking direction of the first to fourth powders was 8 mm.

  In each of the sintered bodies of Examples 6 to 16, a gradation that changes from pale yellow to yellowish white was formed from the region corresponding to the first layer of the composition toward the region corresponding to the fourth layer, It had the same appearance as teeth.

  Then, in the same manner as in Examples 1 to 4, the chromaticity and color difference of the sintered bodies of the first powder, the second powder, the third powder, and the fourth powder were measured. Tables 26 to 35 show the chromaticity. Color differences are shown in Tables 36 to 37.

  It is considered that the chromaticity of each powder represents the chromaticity of each point of the zirconia sintered body produced from the laminated body of a plurality of powders. The combination of the four sintered bodies of Example 9 exhibited a bright color as a whole. The combination of the four sintered bodies of Example 10 exhibited a dark color as a whole.

In the sintered body of the first layer, ^{L *} is 58~76, ^{a *} is -2~8, ^{b *} was 5 to 27. In the sintered body of the second layer, L ^* was 66 to 81, a ^* was -2 to 6, and b ^* was 4 to 21. In the sintered body of the third layer, L ^* was 69 to 83, a ^* was -2 to 2, and b ^* was 3 to 17. In the sintered body of the fourth layer, L ^* was 71 to 84, a ^* was -2 to 1, and b ^* was 2 to 15.

  The color difference between the sintered body of the first layer and the sintered body of the second layer was 3 to 15. The color difference between the second layer sintered body and the third layer sintered body was 1 to 11. The color difference between the third layer sintered body and the fourth layer sintered body was 1 to 4. The color difference between the adjacent layers tended to decrease from the first layer to the fourth layer. The color difference between the first layer sintered body and the fourth layer sintered body was 8 to 29. Color difference between first layer sintered body and second layer sintered body, color difference between second layer sintered body and third layer sintered body, and third layer sintered body and fourth layer sintered body The value obtained by subtracting the color difference between the first layer sintered body and the fourth layer sintered body from the total body color difference was 1 or less.

A single zirconia sintered body was prepared for each of the first powder, the second powder, the third powder, and the fourth powder in Example 9, and the bending strength, fracture toughness, and peak ratio of the monoclinic crystal after hydrothermal treatment were measured. It was measured. The measurement results are shown in Table 38. The bending strength of the zirconia sintered body was measured according to JISR1601. The fracture toughness of the zirconia sintered body was measured according to JISR1607. The hydrothermal treatment test was based on ISO13356 under the conditions of 180 ° C., 1 MPa, and 5 hours. After the hydrothermal treatment test, the X-ray diffraction pattern of the zirconia sintered body was measured by CuKα ray, and the peak ratio of the monoclinic crystal, that is, the degree of phase transition to the monoclinic crystal by the hydrothermal treatment test was measured. Each of the sintered bodies had a bending strength of 1200 MPa or more, a fracture toughness of 4 MPa · m ^1/2 or more, and a monoclinic peak ratio of 1 or less. Since the zirconia sintered bodies in the other examples have the same composition, it is considered that similar results can be obtained. The bending strength and fracture toughness test results were similar to the numerical values when the load was applied to the boundary of the laminate.

  Regarding the second powder, the bending strength of the calcined body produced by firing at 1000 ° C. for 2 hours was also measured according to JIS R1601. The bending strength of the calcined body of the second powder was 41 MPa. This number was similar to the number when tested by applying a load to the boundary of the laminate.

[Example 16]
In the above examples, the yttria content was 4 mol% in the total number of moles of zirconia and yttria, but in Example 16 a 3 mol% sintered body was prepared and the chromaticity was measured. The sintered body used for the measurement is the same as that of Example 4 shown in Tables 14 and 15 except for the yttria content. Table 39 shows the measurement results. As compared with the chromaticity shown in Table 12, when the yttria content was decreased, L ^* tended to decrease, and a ^* and b ^* tended to increase.

  The zirconia sintered body of the present invention, and the composition and the calcined body for the zirconia sintered body have been described based on the above embodiment, but are not limited to the above embodiment, and are within the scope of the present invention. And various modifications to the disclosed elements (including each element of each claim, each element of each embodiment or example, each element of each drawing, etc.) based on the basic technical concept of the present invention. Needless to say, changes and improvements can be included. Further, various combinations and substitutions of various disclosed elements (including each element of each claim, each element of each embodiment or example, each element of each drawing, etc.) within the scope of the claims of the present invention. Or it is possible to select.

  Further problems, objects, and modes of development of the present invention will become apparent from the entire disclosure of the present invention including the claims.

  Regarding the numerical range described in this document, any numerical value or small range included in the range should be construed as specifically described even if not otherwise specified.

［付記２８］
前記第１点から前記第２点を結ぶ直線上において、前記第１点と前記第２点の間にある第３点のＬ＊ａ＊ｂ＊表色系による色度（Ｌ＊，ａ＊，ｂ＊）を（Ｌ３，ａ３，ｂ３）としたとき、
Ｌ３が６９．１以上８２．３以下であり、
ａ３が−２．１以上１．８以下であり、
ｂ３が３．５以上１６．２以下であり、
Ｌ１＜Ｌ３＜Ｌ２であり、
ａ１＞ａ３＞ａ２であり、
ｂ１＞ｂ３＞ｂ２である、
ことを特徴とする付記に記載のジルコニア焼結体。
［付記２９］
一端から他端に向かう第１方向に向かって色が変化しており、
前記一端から前記他端に向かう直線上においてＬ＊ａ＊ｂ＊表色系による色度の増減傾向が変化しないことを特徴とする付記に記載のジルコニア焼結体。
［付記３０］
前記一端と前記他端とを結ぶ直線上において、前記第１点から前記第２点に向かってＬ＊値は増加傾向にあり、ａ＊値及びｂ＊値は減少傾向にあることを特徴とする付記に記載のジルコニア焼結体。
［付記３１］
前記一端から前記他端までの距離は５ｍｍ〜１８ｍｍであることを特徴とする付記に記載のジルコニア焼結体。
［付記３２］
前記第１方向と直交する第２方向に沿って色が変化しないことを特徴とする付記に記載のジルコニア焼結体。
［付記３３］
前記第２方向に延在する直線上の２点において、
前記２点間のＬ＊値の差をΔＬ＊とし、
前記２点間のａ＊値の差をΔａ＊とし、
前記２点間のｂ＊値の差をΔｂ＊とし、
以下の式２よりΔＥ＊ａｂを算出した場合、
ΔＥ＊ａｂが１未満であることを特徴とする付記に記載のジルコニア焼結体。
［式2］

［付記３４］
ＪＩＳＲ１６０１に準拠して測定した曲げ強度が１０００ＭＰａ以上であることを特徴とする付記に記載のジルコニア焼結体。
［付記３５］
ＪＩＳＲ１６０７に準拠して測定した破壊靭性が３．５ＭＰａ・ｍ１／２以上であることを特徴とする付記に記載のジルコニア焼結体。
［付記３６］
１８０℃、１ＭＰａで５時間水熱処理試験を施した後のジルコニア焼結体のＸ線回折パターンにおいて、２θが３０°付近の正方晶由来の［１１１］ピークが生ずる位置付近に存在するピークの高さに対する、２θが２８°付近の単斜晶由来の［１１−１］ピークが生ずる位置付近に存在するピークの高さの比が１以下であることを特徴とする付記に記載のジルコニア焼結体。
［付記３７］
８００℃〜１２００℃で焼成することにより付記に記載の仮焼体となることを特徴とするジルコニア組成物。
［付記３８］
１４００℃〜１６００℃で焼結することにより付記に記載のジルコニア焼結体となることを特徴とするジルコニア組成物。
［付記３９］
付記に記載の仮焼体を切削加工した後に焼結した状態であることを特徴とする歯科用補綴物。
［付記４０］
切削加工は、ＣＡＤ／ＣＡＭシステムを用いて切削加工した後に焼結した状態であることを特徴とする付記に記載の歯科用補綴物。
［付記４１］
ジルコニア及びジルコニアの相転移を抑制する安定化剤を含有し、組成が異なる複数のジルコニア粉末を形成し、
前記複数のジルコニア粉末を積層させてジルコニア組成物を形成し、
前記ジルコニア組成物を焼成して製造された状態のジルコニア仮焼体であって、
前記ジルコニア組成物を８００℃〜１２００℃で焼成して製造されたジルコニア仮焼体を幅５０ｍｍ×高さ１０ｍｍ×奥行き５ｍｍの寸法の直方体形状に成形したものを試験片とし、前記試験片において、幅５０ｍｍ×奥行き５ｍｍとなる面を底面としたとき、前記ジルコニア粉末の積層によって形成される境界面が前記底面と平行になっており、
前記試験片を１５００℃で２時間焼成し、
２つの前記底面のうち、凹面に変形した底面を下にして載置したとき、
（凹面に変形した前記底面と接地面との最大間隔）／（前記幅方向における接地部分間の距離）×１００が０．１５以下であることを特徴とするジルコニア仮焼体。
［付記４２］
ジルコニア及びジルコニアの相転移を抑制する安定化剤を含有し、組成が異なる複数のジルコニア粉末を形成し、
前記複数のジルコニア粉末を積層させてジルコニア組成物を形成し、
前記ジルコニア組成物を焼成して製造された状態のジルコニア仮焼体であって、
前記ジルコニア組成物を８００℃〜１２００℃で焼成して製造されたジルコニア仮焼体の試験片を作製し、
ＪＩＳＲ１６０１に準拠し、層間の境界が荷重印加方向に沿って前記試験片を横断するように存在する前記試験片に対して、３点曲げ試験の荷重点を前記境界の位置に合わせて測定した曲げ強度が、前記複数のジルコニア粉末の１つを単独で前記試験片の仮焼温度と同じ温度で仮焼させたジルコニア仮焼体の曲げ強度の９０％以上であることを特徴とする、ジルコニア仮焼体。
［付記４３］
ジルコニア及びジルコニアの相転移を抑制する安定化剤を含有し、組成が異なる複数のジルコニア粉末を形成し、
前記複数のジルコニア粉末を積層させてジルコニア組成物を形成し、
前記ジルコニア組成物を焼成して製造された状態のジルコニア仮焼体であって、
前記ジルコニア組成物を８００℃〜１２００℃で焼成してジルコニア仮焼体を製造し、前記仮焼体を１４００〜１６００℃で焼成して製造されたジルコニア焼結体の試験片を作製し、
ＪＩＳＲ１６０１に準拠し、層間の境界が荷重印加方向に沿って前記試験片を横断するように存在する前記試験片に対して、３点曲げ試験の荷重点を前記境界の位置に合わせて測定した曲げ強度が、前記複数のジルコニア粉末の１つを単独で前記試験片の焼結温度と同じ温度で焼結させたジルコニア焼結体の曲げ強度の９０％以上であることを特徴とする、ジルコニア仮焼体。
［付記４４］
前記複数のジルコニア粉末は、顔料を含有し、顔料の含有率がそれぞれ異なることを特徴とする付記４１〜４３のいずれか一に記載のジルコニア仮焼体。
［付記４５］
ジルコニア及びジルコニアの相転移を抑制する安定化剤を含有し、組成が異なる複数のジルコニア粉末を形成し、
前記複数のジルコニア粉末を積層させてジルコニア組成物を形成し、
前記ジルコニア組成物を用いて製造された状態のジルコニア焼結体であって、
前記ジルコニア組成物を８００℃〜１２００℃で焼成して製造されたジルコニア仮焼体を幅５０ｍｍ×高さ１０ｍｍ×奥行き５ｍｍの寸法の直方体形状に成形したものを試験片とし、前記試験片において、幅５０ｍｍ×奥行き５ｍｍとなる面を底面としたとき、前記ジルコニア粉末の積層によって形成される境界面が前記底面と平行になっており、
前記試験片を１５００℃で２時間焼成し、
２つの前記底面のうち、凹面に変形した底面を下にして載置したとき、
（凹面に変形した前記底面と接地面との最大間隔）／（前記幅方向における接地部分間の距離）×１００が０．１５以下であることを特徴とするジルコニア焼結体。
［付記４６］
ジルコニア及びジルコニアの相転移を抑制する安定化剤を含有し、組成が異なる複数のジルコニア粉末を形成し、
前記複数のジルコニア粉末を積層させてジルコニア組成物を形成し、
前記ジルコニア組成物を用いて製造された状態のジルコニア焼結体であって、
前記ジルコニア組成物を８００℃〜１２００℃で焼成して製造されたジルコニア仮焼体の試験片を作製し、
ＪＩＳＲ１６０１に準拠し、層間の境界が荷重印加方向に沿って前記試験片を横断するように存在する前記試験片に対して、３点曲げ試験の荷重点を前記境界の位置に合わせて測定した曲げ強度が、前記複数のジルコニア粉末の１つを単独で前記試験片の仮焼温度と同じ温度で仮焼させたジルコニア仮焼体の曲げ強度の９０％以上であることを特徴とする、ジルコニア焼結体。
［付記４７］
ジルコニア及びジルコニアの相転移を抑制する安定化剤を含有し、組成が異なる複数のジルコニア粉末を形成し、
前記複数のジルコニア粉末を積層させてジルコニア組成物を形成し、
前記ジルコニア組成物を用いて製造された状態のジルコニア焼結体であって、
前記ジルコニア組成物を８００℃〜１２００℃で焼成してジルコニア仮焼体を製造し、前記仮焼体を１４００〜１６００℃で焼成して製造されたジルコニア焼結体の試験片を作製し、
ＪＩＳＲ１６０１に準拠し、層間の境界が荷重印加方向に沿って前記試験片を横断するように存在する前記試験片に対して、３点曲げ試験の荷重点を前記境界の位置に合わせて測定した曲げ強度が、前記複数のジルコニア粉末の１つを単独で前記試験片の焼結温度と同じ温度で焼結させたジルコニア焼結体の曲げ強度の９０％以上であることを特徴とする、ジルコニア焼結体。
［付記４８］
前記複数のジルコニア粉末は、顔料を含有し、顔料の含有率がそれぞれ異なることを特徴とする付記４４〜４６のいずれか一に記載のジルコニア焼結体。 The whole or part of the exemplary embodiments disclosed above can be described as, but not limited to, the following supplementary notes.
[Appendix 1]
Contains a stabilizer that suppresses the phase transition of zirconia and zirconia, to form a plurality of zirconia powders having different compositions,
A plurality of zirconia powders are laminated to form a zirconia composition,
A zirconia sintered body is produced by sintering the zirconia composition,
According to JISR1601, the load point of the three-point bending test is set to the position of the boundary with respect to the test piece of the sintered body in which the boundaries of the plurality of zirconia powders cross the test piece along the load application direction. A zirconia sintered body having a bending strength of 1100 MPa or more, which is measured in accordance with the above.
[Appendix 2]
The zirconia sintered body according to the appendix, wherein the bending strength is 1200 MPa or more.
[Appendix 3]
When a zirconia calcined body is produced by calcining the zirconia composition at 800 ° C. to 1200 ° C.,
According to JISR1601, the load point of the three-point bending test is set to the position of the boundary with respect to the test piece of the calcined body in which the boundaries of the plurality of zirconia powders cross the test piece along the load application direction. The bending strength measured according to the above is 90% or more of the bending strength of the zirconia calcined body obtained by calcining one of the zirconia powders alone at the same temperature as the calcination temperature of the test piece. The zirconia sintered body according to the appendix.
[Appendix 4]
The zirconia sintered body according to the supplementary note, wherein the plurality of zirconia powders contain a pigment, and the content rates of the pigments are different from each other.
[Appendix 5]
The zirconia sintered body according to the supplementary note, wherein each of the sintered bodies obtained by sintering the plurality of zirconia powders alone at 1500 ° C. has a bending strength of 1100 MPa or more measured according to JISR1601.
[Appendix 6]
Contains a stabilizer that suppresses the phase transition of zirconia and zirconia, to form a plurality of zirconia powders having different compositions,
A plurality of zirconia powders are laminated to form a zirconia composition,
A zirconia calcined body obtained by calcining the composition at 800 ° C. to 1200 ° C.,
According to JISR1601, the load point of the three-point bending test is set to the position of the boundary with respect to the test piece of the calcined body in which the boundaries of the plurality of zirconia powders cross the test piece along the load application direction. The bending strength measured according to the above is 90% or more of the bending strength of the zirconia calcined body obtained by calcining one of the zirconia powders alone at the same temperature as the calcination temperature of the test piece. A zirconia calcined body.
[Appendix 7]
The zirconia calcined body according to the appendix, wherein the plurality of zirconia powders contain a pigment, and the content rates of the pigments are different.
[Appendix 8]
Zirconia, containing a stabilizer and a pigment to suppress the phase transition of zirconia, a step of producing a plurality of lamination powder different content of the pigment,
Laminating step of laminating a plurality of the laminating powder in a mold,
A method for producing a zirconia composition, which comprises vibrating the mold after filling the mold with at least two powders for lamination in the laminating step.
[Appendix 9]
The method for producing a zirconia composition according to the appendix, wherein in the laminating step, the mold is vibrated every time one of the laminating powders is filled in the mold.
[Appendix 10]
Zirconia, containing a stabilizer and a pigment that suppresses the phase transition of zirconia, a step of producing a low addition rate powder and a high addition rate powder having different content rates of the pigment,
A mixing step of mixing the low addition rate powder and the high addition rate powder to produce at least one laminating powder;
A laminating step of laminating at least two powders in the mold among the low addition rate powder, the high addition rate powder and the lamination powder;
The manufacturing method of the zirconia composition characterized by including these.
[Appendix 11]
The method for producing a zirconia composition according to the appendix, wherein in the laminating step, the mold is vibrated after at least two powders are filled in the mold.
[Appendix 12]
In the mixing step, two or more powders for lamination having different mixing ratios of the low addition rate powder and the high addition rate powder are produced,
The method for producing a zirconia composition according to the supplementary note, wherein in the laminating step, a plurality of powders are laminated so that the content rates of the low-addition rate powder and the high-addition rate powder change in order.
[Appendix 13]
The method for producing a zirconia composition according to the supplementary note, wherein in the laminating step, after filling one powder into the mold, the upper surface of the powder is flattened.
[Appendix 14]
In the said lamination process, the said powder is laminated | stacked so that the content rate of the pigment in a powder may change in order, The manufacturing method of the zirconia composition of the additional statement characterized by the above-mentioned.
[Appendix 15]
A method for producing a zirconia composition according to the supplementary notes,
Baking the composition at 800 ° C. to 1200 ° C .;
A method for producing a zirconia calcined body, comprising:
[Appendix 16]
A method for producing a zirconia composition according to the supplementary notes,
Baking the composition at 1400 ° C to 1600 ° C;
A method for producing a zirconia sintered body, comprising:
[Appendix 17]
A method for producing a zirconia calcined body according to the supplementary notes,
A step of firing the calcined body at 1400 ° C to 1600 ° C,
A method for producing a zirconia sintered body, comprising:
[Appendix 18]
It contains yttria as a stabilizer that suppresses the phase transition of zirconia and zirconia, forming a plurality of zirconia powders having different compositions,
A plurality of zirconia powders are laminated to form a zirconia composition,
A zirconia calcined body produced by firing the zirconia composition at 800 ° C to 1200 ° C.
When the calcined body is molded into a rectangular parallelepiped shape having dimensions of width 50 mm × height 10 mm × depth 5 mm, the resulting zirconia powder is used as a test piece. The boundary surface formed by stacking of is parallel to the bottom surface,
Baking the test piece at 1500 ° C. for 2 hours,
Of the two bottom surfaces, when placed with the bottom surface transformed into a concave surface facing down,
(Maximum distance between the bottom surface deformed into a concave surface and the ground contact surface) / (distance between ground contact portions in the width direction) × 100 is 0.15 or less, and the zirconia calcined body is characterized.
[Appendix 19]
(Maximum distance between the bottom surface deformed into a concave surface and the ground contact surface) / (distance between ground contact portions in the width direction) × 100 is 0.1 or less, and the zirconia calcined body is added.
[Appendix 20]
The zirconia calcined body according to the appendix, wherein the plurality of zirconia powders contain a pigment, and the content rates of the pigments are different.
[Appendix 21]
A zirconia sintered body, characterized in that it is in a state in which the zirconia calcined body described in the appendix is sintered at 1400 ° C to 1600 ° C.
[Appendix 22]
On a straight line extending from one end to the other in the first direction,
The chromaticity (L *, a *, b *) by the L * a * b * color system of the first point in the section from one end to 25% of the total length is (L1, a1, b1),
When the chromaticity (L *, a *, b *) according to the L * a * b * color system of the second point in the section from the other end to 25% of the total length is (L2, a2, b2) ,
L1 is 58.0 or more and 76.0 or less,
a1 is −1.6 or more and 7.6 or less,
b1 is 5.5 or more and 26.7 or less,
L2 is 71.8 or more and 84.2 or less,
a2 is −2.1 or more and 1.8 or less,
b2 is 1.9 or more and 16.0 or less,
L1 <L2,
a1> a2,
b1> b2,
The zirconia sintered body according to the appendix, wherein the increasing / decreasing tendency of chromaticity by the L * a * b * color system does not change from the first point to the second point.
[Appendix 23]
On a straight line connecting the first point and the second point,
There is no section in which the L * value decreases by 1 or more from the first point to the second point,
There is no section in which the a * value increases by 1 or more from the first point to the second point,
The zirconia sintered body according to the appendix, wherein there is no section in which the b * value increases by 1 or more from the first point to the second point.
[Appendix 24]
On the straight line connecting the first point and the second point, the chromaticity (L *, a * by the L * a * b * colorimetric system of the third point between the first point and the second point , B *) is (L3, a3, b3),
L3 is 62.5 or more and 80.5 or less,
a3 is -1.8 or more and 5.5 or less,
b3 is 4.8 or more and 21.8 or less,
L1 <L3 <L2,
a1>a3> a2,
b1>b3> b2,
The zirconia sintered body according to the supplementary note characterized by the above.
[Appendix 25]
On the straight line connecting the first point and the second point, the chromaticity (L *, a *) of the fourth point between the third point and the second point by the L * a * b * color system. , B *) is (L4, a4, b4),
L4 is 69.1 or more and 82.3 or less,
a4 is -2.1 or more and 1.8 or less,
b4 is 3.5 or more and 16.2 or less,
L1 <L3 <L4 <L2,
a1>a3>a4> a2,
b1>b3>b4> b2,
The zirconia sintered body according to the supplementary note characterized by the above.
[Appendix 26]
The third point is at a distance of 45% of the total length from the one end,
The fourth point is 55% of the total length from the one end,
The zirconia sintered body according to the supplementary note characterized by the above.
[Appendix 27]
At the first point, the third point, the fourth point and the second point,
Let ΔL * be the difference between the L * values at two adjacent points,
Let Δa * be the difference between a * values at two adjacent points,
The difference between the b * values at two adjacent points is Δb *,
When ΔE * ab is calculated from the following Equation 1,
ΔE * ab between the first point and the third point is 3.7 or more and 14.3 or less,
ΔE * ab between the third point and the fourth point is 1.8 or more and 10.5 or less,
ΔE * ab between the fourth point and the second point is 1.0 or more and 9.0 or less,
The zirconia sintered body according to the supplementary note characterized by the above.
[Formula 1]

[Appendix 28]
On the straight line connecting the first point and the second point, the chromaticity (L *, a * by the L * a * b * colorimetric system of the third point between the first point and the second point , B *) is (L3, a3, b3),
L3 is 69.1 or more and 82.3 or less,
a3 is −2.1 or more and 1.8 or less,
b3 is 3.5 or more and 16.2 or less,
L1 <L3 <L2,
a1>a3> a2,
b1>b3> b2,
The zirconia sintered body according to the supplementary note characterized by the above.
[Appendix 29]
The color changes in the first direction from one end to the other,
The zirconia sintered body according to the appendix, wherein the tendency of increase or decrease in chromaticity due to the L * a * b * color system does not change on a straight line extending from the one end to the other end.
[Appendix 30]
On a straight line connecting the one end and the other end, the L * value tends to increase and the a * value and the b * value tend to decrease from the first point to the second point. The zirconia sintered body according to the appendix.
[Appendix 31]
The distance between the one end and the other end is 5 mm to 18 mm, and the zirconia sintered body according to the supplementary notes.
[Appendix 32]
The zirconia sintered body according to the appendix, wherein the color does not change along a second direction orthogonal to the first direction.
[Appendix 33]
At two points on a straight line extending in the second direction,
The difference between the L * values between the two points is ΔL *,
The difference between the a * values between the two points is Δa *,
The difference in b * value between the two points is Δb *,
When ΔE * ab is calculated from the following equation 2,
ΔE * ab is less than 1, zirconia sintered body according to the supplementary notes.
[Formula 2]

[Appendix 34]
The bending strength measured according to JISR1601 is 1000 MPa or more, The zirconia sintered body according to the appendix, characterized in that.
[Appendix 35]
Fracture toughness measured according to JIS R1607 is 3.5 MPa · m1 / 2 or more, the zirconia sintered body according to the supplementary notes.
[Appendix 36]
In the X-ray diffraction pattern of the zirconia sintered body after being subjected to the hydrothermal treatment test at 180 ° C. and 1 MPa for 5 hours, the height of the peak existing near the position where the tetragonal [111] peak where 2θ is around 30 ° occurs. The ratio of the height of the peak existing near the position where the [11-1] peak derived from the monoclinic crystal having a 2θ of about 28 ° to 1 is 1 or less with respect to the zirconia sintering. body.
[Appendix 37]
A zirconia composition, wherein the calcined body described in the supplementary notes is obtained by firing at 800 ° C to 1200 ° C.
[Appendix 38]
A zirconia composition, wherein the zirconia sintered body described in the supplementary note is obtained by sintering at 1400 ° C to 1600 ° C.
[Appendix 39]
A dental prosthesis, characterized in that it is in a state of being sintered after cutting the calcined body described in the appendix.
[Appendix 40]
The dental prosthesis according to the supplementary note, wherein the cutting process is a state in which the cutting process is performed using a CAD / CAM system and then the sintering process is performed.
[Appendix 41]
Contains a stabilizer that suppresses the phase transition of zirconia and zirconia, to form a plurality of zirconia powders having different compositions,
A plurality of zirconia powders are laminated to form a zirconia composition,
A zirconia calcined body produced by firing the zirconia composition,
A zirconia calcined body produced by firing the zirconia composition at 800 ° C. to 1200 ° C. was molded into a rectangular parallelepiped shape having dimensions of width 50 mm × height 10 mm × depth 5 mm. When a surface having a width of 50 mm and a depth of 5 mm is a bottom surface, a boundary surface formed by stacking the zirconia powder is parallel to the bottom surface,
Baking the test piece at 1500 ° C. for 2 hours,
Of the two bottom surfaces, when placed with the bottom surface transformed into a concave surface facing down,
(Maximum distance between the bottom surface deformed into a concave surface and the ground contact surface) / (distance between ground contact portions in the width direction) × 100 is 0.15 or less, and the zirconia calcined body is characterized.
[Appendix 42]
Contains a stabilizer that suppresses the phase transition of zirconia and zirconia, to form a plurality of zirconia powders having different compositions,
A plurality of zirconia powders are laminated to form a zirconia composition,
A zirconia calcined body produced by firing the zirconia composition,
A test piece of a zirconia calcined body produced by firing the zirconia composition at 800 ° C. to 1200 ° C. is produced,
Bending measured according to JIS R1601 with respect to the test piece in which the boundary between layers exists so as to cross the test piece along the load application direction, and the load point of the three-point bending test was measured according to the position of the boundary. The strength is 90% or more of the bending strength of a zirconia calcined body obtained by calcining one of the plurality of zirconia powders alone at the same temperature as the calcining temperature of the test piece. Burned body.
[Appendix 43]
Contains a stabilizer that suppresses the phase transition of zirconia and zirconia, to form a plurality of zirconia powders having different compositions,
A plurality of zirconia powders are laminated to form a zirconia composition,
A zirconia calcined body produced by firing the zirconia composition,
The zirconia composition is fired at 800 ° C. to 1200 ° C. to produce a zirconia calcined body, and a test piece of a zirconia sintered body produced by firing the calcined body at 1400 to 1600 ° C. is produced,
Bending measured according to JIS R1601 with respect to the test piece in which the boundary between layers exists so as to cross the test piece along the load application direction, and the load point of the three-point bending test was measured according to the position of the boundary. The strength is 90% or more of the bending strength of a zirconia sintered body obtained by independently sintering one of the plurality of zirconia powders at the same temperature as the sintering temperature of the test piece. Burned body.
[Appendix 44]
The zirconia calcined body according to any one of appendices 41 to 43, wherein each of the plurality of zirconia powders contains a pigment, and the content rates of the pigments are different from each other.
[Appendix 45]
Contains a stabilizer that suppresses the phase transition of zirconia and zirconia, to form a plurality of zirconia powders having different compositions,
A plurality of zirconia powders are laminated to form a zirconia composition,
A zirconia sintered body in a state manufactured using the zirconia composition,
A zirconia calcined body produced by firing the zirconia composition at 800 ° C. to 1200 ° C. was molded into a rectangular parallelepiped shape having dimensions of width 50 mm × height 10 mm × depth 5 mm. When a surface having a width of 50 mm and a depth of 5 mm is a bottom surface, a boundary surface formed by stacking the zirconia powder is parallel to the bottom surface,
Baking the test piece at 1500 ° C. for 2 hours,
Of the two bottom surfaces, when placed with the bottom surface transformed into a concave surface facing down,
(Maximum distance between the bottom surface deformed into a concave surface and the ground contact surface) / (distance between ground contact portions in the width direction) × 100 is 0.15 or less, a zirconia sintered body.
[Appendix 46]
Contains a stabilizer that suppresses the phase transition of zirconia and zirconia, to form a plurality of zirconia powders having different compositions,
A plurality of zirconia powders are laminated to form a zirconia composition,
A zirconia sintered body in a state manufactured using the zirconia composition,
A test piece of a zirconia calcined body produced by firing the zirconia composition at 800 ° C. to 1200 ° C. is produced,
Bending measured according to JIS R1601 with respect to the test piece in which the boundary between layers exists so as to cross the test piece along the load application direction, and the load point of the three-point bending test was measured according to the position of the boundary. The strength is 90% or more of the bending strength of a zirconia calcined body obtained by calcining one of the plurality of zirconia powders alone at the same temperature as the calcination temperature of the test piece. Union.
[Appendix 47]
Contains a stabilizer that suppresses the phase transition of zirconia and zirconia, to form a plurality of zirconia powders having different compositions,
A plurality of zirconia powders are laminated to form a zirconia composition,
A zirconia sintered body in a state manufactured using the zirconia composition,
The zirconia composition is fired at 800 ° C. to 1200 ° C. to produce a zirconia calcined body, and a test piece of a zirconia sintered body produced by firing the calcined body at 1400 to 1600 ° C. is produced,
Bending measured according to JIS R1601 with respect to the test piece in which the boundary between layers exists so as to cross the test piece along the load application direction, and the load point of the three-point bending test was measured according to the position of the boundary. The strength is 90% or more of the bending strength of a zirconia sintered body obtained by sintering one of the plurality of zirconia powders alone at the same temperature as the sintering temperature of the test piece, zirconia firing Union.
[Appendix 48]
The zirconia sintered body according to any one of appendices 44 to 46, wherein the plurality of zirconia powders contain a pigment, and the content ratios of the pigments are different from each other.

  The zirconia sintered body of the present invention is a dental material such as a prosthesis, an optical fiber connecting part such as a ferrule or a sleeve, various tools (for example, a crushing ball, a grinding tool), various parts (for example, screws, bolts and nuts). ), Various sensors, electronic parts, ornaments (for example, watch bands), and various other uses. When the zirconia sintered body is used for a dental material, for example, coping, framework, crown, crown bridge, abutment, implant, implant screw, implant fixture, implant bridge, implant bar, bracket, denture base, inlay, It can be used for onlays, onlays, straightening wires, laminated veneers and the like.

10 Zirconia Sintered Body 20,22 Calcined Body 20a, 22a Bottom Surface 21a, 21b First Layer, Second Layer 23a-23d First-Fourth Layer 30 Ground Surface A-D First Point-Fourth Point P One End Q Other end X First direction Y Second direction

Claims (7)

A zirconia calcined body containing a stabilizer that suppresses a phase transition of zirconia and zirconia, and firing a laminate composed of a plurality of zirconia layers having different compositions,
When the zirconia calcined body is molded into a rectangular parallelepiped shape having a width of 50 mm, a height of 10 mm, and a depth of 5 mm, a test piece is prepared. When the surface of the test piece having a width of 50 mm and a depth of 5 mm is a bottom surface, The boundary surface formed by the zirconia layer of is parallel to the bottom surface,
Baking the test piece at 1500 ° C. for 2 hours,
Of the two bottom surfaces, when placed with the bottom surface transformed into a concave surface facing down,
(Maximum distance between the bottom surface deformed into a concave surface and the ground surface) / (distance between ground portions in the width direction) × 100 is 0.15 or less,
A zirconia calcined body containing 0% by mass to 0.3% by mass of aluminum oxide with respect to the total mass of the zirconia and the stabilizer. A zirconia calcined body containing a stabilizer that suppresses phase transition of zirconia and zirconia, and firing a laminate composed of a plurality of zirconia layers having different compositions,
Making a test piece of the zirconia calcined body,
Bending measured according to JIS R1601 by applying a load point of a three-point bending test to the position of the boundary with respect to the test piece in which the boundary between layers exists so as to cross the test piece along the load application direction. The strength is 90% or more of the bending strength of the zirconia calcined body composed of one of the plurality of zirconia layers,
A zirconia calcined body containing 0% by mass to 0.3% by mass of aluminum oxide with respect to the total mass of the zirconia and the stabilizer. A zirconia calcined body containing a stabilizer that suppresses phase transition of zirconia and zirconia, and firing a laminate composed of a plurality of zirconia layers having different compositions,
A test piece of a zirconia sintered body produced by firing the zirconia calcined body at 1400 to 1600 ° C. is produced,
Bending measured according to JIS R1601 by applying a load point of a three-point bending test to the position of the boundary with respect to the test piece in which the boundary between layers exists so as to cross the test piece along the load application direction. The strength is 90% or more of the bending strength of a zirconia sintered body obtained by sintering a zirconia calcined body composed of one of the plurality of zirconia layers at the same temperature as the sintering temperature of the test piece,
A zirconia calcined body containing 0% by mass to 0.3% by mass of aluminum oxide with respect to the total mass of the zirconia and the stabilizer.   The zirconia calcined body according to any one of claims 1 to 3, which is for dental use. A zirconia sintered body containing a stabilizer that suppresses a phase transition of zirconia and zirconia, and a zirconia sintered body obtained by firing a laminate composed of a plurality of zirconia layers having different compositions,
Making a test piece of the zirconia sintered body,
Bending measured according to JIS R1601 with respect to the test piece in which the boundary between layers exists so as to cross the test piece along the load application direction, and the load point of the three-point bending test was measured according to the position of the boundary. The strength is 90% or more of the bending strength of the zirconia sintered body composed of one of the plurality of zirconia layers,
A zirconia sintered body containing 0% by mass to 0.3% by mass of aluminum oxide with respect to the total mass of the zirconia and the stabilizer.   The zirconia sintered body according to claim 5, which is for dental use. A zirconia and a stabilizer that suppresses a phase transition of zirconia are contained, and the zirconia layer is composed of a plurality of different compositions. % Containing laminate,
The zirconia calcined body according to any one of claims 1 to 4 by firing at 800 to 1200 ° C, and / or the zirconia according to claim 5 or 6 by firing at 1400 to 1600 ° C. A laminated body, which is a sintered body.

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