JP2020147495A - Zirconia calcined body - Google Patents

Abstract

To provide at least any of a layered body which has a change in color tone and in which it is unnecessary to select a colorant and the content of the colorant in consideration of a difference in the sintering behavior between layers, a precursor thereof, and a method for producing them.SOLUTION: A calcined body is provided that has structure in which two or more layers containing stabilizer-containing zirconia and a colorant are layered, and in which types and contents of the colorants contained in the layers are equal to each other, the layered body including at least: a first layer containing a colorant and zirconia which has a stabilizer content of higher than or equal to 3.3 mol%; and a second layer containing a colorant and zirconia which has a stabilizer content different from that of the zirconia contained in the first layer.SELECTED DRAWING: None

Description

The present disclosure relates to a composition in which zirconia layers are laminated, and further to a zirconia laminate.

The zirconia (ZrO ₂ ) sintered body is mainly produced by molding and sintering a raw material powder containing zirconia. The raw material powder is heat-shrinked and densified by heat treatment such as sintering and calcining, but the behavior during the heat treatment differs depending on the characteristics of the raw material powder, particularly the composition of the raw material powder.

Even if the raw material powders have different content of additives of less than 0.1% by mass, when the molded product in which they are laminated is heat-treated, the sintering behavior of each layer differs due to the difference in composition. Special adjustments and treatments have been required in order to obtain a laminate having a change in color tone without causing such a defect (for example, Patent Documents 1 and 2).

Patent Document 1 discloses that a sintered body composed of laminates having different color tones can be obtained by adjusting the composition and heat shrinkage behavior of the raw material powder by coating with a dopant and molding the raw material powder. .. Further, in Patent Document 2, the layers having different colorant contents are formed by applying vibration to form a boundary layer in which the powders of the upper and lower layers are mixed to form the layers, and the layers have different color tones. It is disclosed that a sintered body made of a laminated body can be obtained.

Special Table 2016-527017 Japanese Unexamined Patent Publication No. 2014-218389

The laminates disclosed in Patent Documents 1 and 2 impart a change in color tone by changing the content of additives between layers. However, in these laminates, the colorant for each layer and its content are selected in consideration of the difference in sintering behavior for each layer due to the difference in the content of the colorant in addition to the desired color tone. I had to do it.

The present disclosure does not require selection of a colorant and its content in consideration of the difference in sintering behavior for each layer, and at least one of a laminate having a change in color tone, a precursor thereof, or a method for producing them is used. The purpose is to provide. From another point of view, it is an object of the present invention to provide at least one of a laminate suitable as a dental prosthetic member, a precursor thereof, or a method for producing them.

The present inventors paid attention to the state of zirconia, which occupies most of the laminate, when producing the laminate having a change in color tone. As a result, it was found that by laminating raw material powders having different contents of zirconia stabilizers, a change in color tone is imparted to the laminated body by a mechanism different from that of the conventional laminated body.

That is, the gist of the present disclosure is as follows.
[1] Coloring contained in each zirconia composition layer having a structure in which two or more zirconia composition layers containing a stabilizer and having a necking structure and a colorant are laminated. The agents and their contents are equal to each other, at least
A first zirconia composition layer containing a zirconia having a stabilizer content of 3.3 mol% or more and a colorant, and the like.
A second zirconia composition layer containing a zirconia contained in the first zirconia composition layer and a zirconia having a different content of a stabilizer and a colorant, and a second zirconia composition layer.
A calcined body characterized by being provided with.
[2] The calcining according to the above [1], wherein the content of the zirconia stabilizer containing the stabilizer contained in the second zirconia composition layer is 1.5 mol% or more and 7.0 mol% or less. body.
[3] In the above [1] or [2], the content of the zirconia stabilizer containing the stabilizer contained in the second zirconia composition layer is 4.5 mol% or more and 7.0 mol% or less. The described calcined body.
[4] The above [1] to [3], wherein the content of the zirconia stabilizer containing the stabilizer contained in the first zirconia composition layer is 3.3 mol% or more and 5.5 mol% or less. The calcined body described in any one.
[5] The difference between the stabilizer content of the first zirconia composition layer and the stabilizer content of the second zirconia composition layer is 0.2 mol% or more [1] to [4]. The calcined body described in any one of.
[6] Stabilizers include yttrium (Y ₂ O ₃ ), calcia (CaO), magnesia (MgO) and ceria (CeO ₂ ), placeodymium oxide (Pr ₆ O ₁₁ ), neodymium oxide (Nd ₂ O ₃ ), Described in any one of the above [1] to [5], which is one or more selected from the group of terbium oxide (Tb ₄ O ₇ ), erbium oxide (Er ₂ O ₃ ) and ytterbium oxide (Yb ₂ O ₃ ). Temporary roasted body.
[7] The calcined product according to any one of the above [1] to [6], wherein the colorant is at least one of a transition metal element and a lanthanoid rare earth element.
[8] The calcined product according to any one of the above [1] to [7], wherein the content of the colorant is 0.01% by mass or more and 1.0% by mass or less.
[9] The calcined product according to any one of the above [1] to [8], wherein at least one layer of the zirconia composition layer contains alumina.
[10] The calcined body according to any one of the above [1] to [9], wherein the warp measured by using a feeler gauge conforming to JIS B 7524: 2008 is 1.0 mm or less.
[11] It has a structure in which two or more powder composition layers composed of a powder composition containing zirconia containing a stabilizer, a colorant, and a binder are laminated, and is contained in each powder composition layer. Colorants and their contents are equal to each other, at least
A first powder composition layer containing zirconia having a stabilizer content of 3.3 mol% or more, a colorant, and a binder.
A second powder composition layer containing zirconia and a stabilizer contained in the first powder composition layer having different contents, a coloring agent, and a binder.
With
A step of calcining a molded product in which the difference in the content of the binder between the first powder composition layer and the second powder composition layer exceeds 0.01% by mass at 800 ° C. or higher and lower than 1200 ° C. The method for producing a calcined product according to any one of the above [1] to [10], which comprises.
[12] The production method according to the above [11], wherein the binder is at least one selected from the group of polyvinyl alcohol, polyvinyl butyrate, wax and acrylic resin.
[13] The production method according to the above [11] or [12], wherein the powder composition contained in the powder composition layer is a powder in a granulated state.
[14] The dental material containing the calcined body according to any one of the above [1] to [10].

The present disclosure provides a laminate having a change in color tone, a precursor thereof, or a method for producing the same, without requiring selection of a colorant and its content in consideration of the difference in sintering behavior for each layer. can do. Furthermore, at least one of a laminate suitable as a dental prosthesis member, a precursor thereof, or a method for producing the same can be provided.

Schematic diagram showing zirconia having a necking structure Schematic diagram showing a cross section of a calcined body having a structure in which two zirconia composition layers are laminated. Schematic diagram showing a cross section of a calcined body having a structure in which three layers of zirconia composition are laminated. Schematic diagram showing the method of measuring warpage Schematic diagram showing a method for measuring three-point bending strength

Hereinafter, the calcined body of the present disclosure will be described with reference to an example of the embodiment.

In this embodiment, zirconia containing a stabilizer and having a necking structure is used.
It has a structure in which two or more zirconia composition layers containing a colorant are laminated, and the colorants contained in each zirconia composition layer and their contents are equal to each other, and at least,
A first zirconia composition layer containing a zirconia having a stabilizer content of 3.3 mol% or more and a colorant, and the like.
A second zirconia composition layer containing a zirconia contained in the first zirconia composition layer and a zirconia having a different content of a stabilizer and a colorant, and a second zirconia composition layer.
It is a calcined body, which is characterized by being provided with.

The calcined body of the present embodiment is a composition having a multi-layer structure, a so-called laminated body, and a laminated body composed of a structure having a necking structure, so-called calcined particles. The calcined body can be processed as needed and used as a precursor of the sintered body, and is also called a pre-sintered body or a semi-sintered body.

The necking structure is a structure possessed by zirconia heat-treated at a temperature lower than the sintering temperature, and is a structure in which zirconia particles are chemically adhered to each other. As shown in FIG. 1, in the zirconia (11) contained in the zirconia composition layer of the calcined product, a part of the particle shape of zirconia in the powder composition can be confirmed. In the present embodiment, the structure having a necking structure is a structure made of zirconia in the initial stage of sintering. This is different from the sintered structure, that is, the structure composed of zirconia crystal particles in the late stage of sintering. Therefore, the calcined body of the present embodiment can be regarded as a laminate having two or more layers containing zirconia having a zirconia necking structure containing a stabilizer and a colorant. ..

FIG. 2 is a schematic view showing an example of the structure of the calcined body of the present embodiment, and has two layers of a zirconia composition layer containing a stabilizer and having a necking structure and a colorant. The cross section of the calcined body (200) having a laminated structure is schematically shown. In FIG. 2, the direction in which the layers are stacked (hereinafter, also referred to as “stacking direction”) is shown in the Y-axis direction, and the direction in which each layer spreads (hereinafter, also referred to as “horizontal direction”) is shown in the X-axis direction. ..

The calcined product (200) is a first zirconia composition layer containing a zirconia having a stabilizer content of 4 mol% or more and a colorant among the zirconia composition layers (hereinafter, "first composition"). A second zirconia composition layer containing a zirconia having a stabilizer content different from that of the zirconia contained in the first zirconia composition layer (21) and a colorant (hereinafter referred to as a layer) (hereinafter, also referred to as a layer). , (Also referred to as "second composition layer") (22), and has a structure in which the first composition layer (21) and the second composition layer (22) are laminated adjacent to each other. Shown as roasted body. By having a structure in which zirconia composition layers containing zirconia having different stabilizer contents are laminated, a sintered body obtained by sintering this has a difference in stabilizer content, translucency, etc. It becomes a laminated body in which a color change based on a synergistic action can be visually recognized. In the calcined body (200), the first composition layer and the second composition layer are in contact with each other via an interface. However, the calcined body of the present embodiment may be laminated without having a visible interface, and the interface between the layers is not limited to a linear one.

In the calcined body (200), the thicknesses of the first composition layer and the second composition layer are shown to be about the same. However, in the calcined body of the present embodiment, the thickness of each layer (hereinafter, also referred to as “layer thickness”) may be different, and either the first composition layer or the second composition layer may be different. The layer thickness may be thick. For example, the layer thicknesses of the first composition layer and the second composition layer satisfy the following relationship, and the composition has a large stabilizer content with respect to the layer thickness of the composition layer having a low stabilizer content. For example, the thickness of the material layer is thick. No. The layer thickness is 1 mm or more and 20 mm or less, further 2 mm or more and 15 mm or less, and further 3 mm or more and 10 mm or less.

_{D high} ≧ D _low, preferably _{2 × D low ≧ D high ≧} D low
However, D _high is the layer thickness of the zirconia layer having a _high stabilizer content, and D _low is the layer thickness of the zirconia layer having a _low stabilizer content.

The shape of the calcined body of the present embodiment is arbitrary, and at least one selected from the group of spherical, elliptical, disk-shaped, columnar, cubic, rectangular parallelepiped, and polyhedral, crown, bridge, onlay, and Any shape suitable for dental materials such as dental seat prosthesis materials such as onlays and other shapes according to the intended use may be used. In the present embodiment, the spherical shape includes a true sphere-like shape other than a true sphere such as a substantially spherical shape, and the polyhedron shape may include a polyhedron-like shape such as a substantially polyhedron shape in addition to the polyhedron.

The dimensions of the calcined body of the present embodiment are arbitrary, and examples thereof include a length of 10 mm or more and 120 mm or less, a width of 12 mm or more and 120 mm or less, and a height of 6 mm or more and 40 mm or less. The thickness of the calcined body in the stacking direction of the present embodiment, that is, the height of the calcined body is arbitrary, and may be, for example, 4 mm or more and 40 mm or less, and further 5 mm or more and 30 mm or less.

In the calcined body of the present embodiment, it is preferable that the first composition layer and the second composition layer are laminated adjacent to each other. Further, the first composition layer and the second composition layer are each the lowest layer in the stacking direction (hereinafter, also referred to as "bottom layer") or the top layer in the stacking direction (hereinafter, "top layer"). Also referred to as)). Preferably, one layer of the first composition layer or the second composition layer is located at the bottom layer, and the other layer of the first composition layer or the second composition layer is located at the top layer. preferable.

The calcined product of the present embodiment may have a structure in which two or more zirconia composition layers containing a stabilizer and a zirconia composition layer containing a colorant are laminated, and the zirconia composition layer is three or more layers. Further, it may have a structure in which four or more layers are laminated. As the number of layers increases, the sintered body obtained by sintering this becomes a laminated body in which fine changes in texture can be visually recognized. When the texture of the sintered body is to be more similar to that of natural teeth, the calcined body of the present embodiment has two or more and 10 or less zirconia composition layers, further 2 or more and 5 or less layers, and further. Can be exemplified as a structure in which two or more layers and four or less layers are laminated.

The zirconia composition layer other than the first composition layer and the second composition layer (hereinafter, also referred to as “third composition layer”) is stable of zirconia contained in the first composition layer and the second composition layer. Any zirconia composition layer containing a zirconia containing a stabilizer containing a stabilizer content of not less than the minimum value and not more than the maximum value of the agent content and a colorant may be used. The calcined body of the present embodiment may contain a plurality of third composition layers.

The stacking order of the third composition layer is arbitrary, but it is preferable that the third composition layer is sandwiched between the first composition layer and the second composition layer. A plurality of third composition layers (the first third composition layer is the "third layer", the second and higher third composition layers are the "fourth composition layer", and the "fifth composition layer". Etc.), the calcined product of the present embodiment has a zirconia composition layer such that the change in the content of the stabilizer in the stacking direction is constant, that is, increases (or decreases). It is preferable to have a laminated structure. In the present embodiment, the structure in which the third composition layer is sandwiched between the first composition layer and the second composition layer means that the first composition layer and the second composition layer are laminated in the stacking direction. The structure is such that the third composition layer is located between them, and the structure is not limited to the structure in which the third composition layer is laminated directly adjacent to both the first composition layer and the second composition layer. Further, in the present embodiment, the first, second, third ... Are numbers given for convenience of explanation, and do not mean a permutation such as a stacking order or a stacking state.

FIG. 3 is a schematic view showing another example of the structure of the calcined body of the present embodiment, and is a schematic view showing a cross section of the calcined body (300) having a structure in which three layers of zirconia composition layers are laminated. .. The calcined body (300) has a structure in which a third composition layer (33) is laminated in addition to the first composition layer (31) and the second composition layer (32), and the first composition layer (300) It has a structure in which the third composition layer (33) is sandwiched between the second composition layer (32) and the second composition layer (32).

When a plurality of zirconia composition layers such as a fourth composition layer and a fifth composition layer are included, the structure is such that the zirconia composition layers are laminated so that the content of the stabilizer changes constantly in the stacking direction. Is preferable. As a result, in the sintered body obtained by sintering the calcined body of the present embodiment, a gradation of color tone can be formed based on the synergistic action of the content difference of the stabilizer and the translucency.

The calcined body of the present embodiment preferably has a warp (hereinafter, also simply referred to as “warp”) of 1.0 mm or less measured using a feeler gauge conforming to JIS B 7524: 2008. A calcined body having a structure having two or more zirconia composition layers is formed into a shape warped in the laminating direction (or the direction opposite to the laminating direction) by heat treatment. When such a calcined body is arranged on the horizontal plate, a gap is formed between the calcined body and the horizontal plate.

The warp in this embodiment is a value measured using a feeler gauge (hereinafter, also simply referred to as “gauge”) conforming to JIS B 7524: 2008. The warpage of the calcined body of the present embodiment is preferably 0.3 mm or less, more preferably 0.2 mm or less, still more preferably 0.1 mm or less, still more preferably 0.05 mm or less. The calcined body preferably has no warp (warp is 0 mm), but the calcined body of the present embodiment may have a warp that cannot be measured by a gauge (warp is 0 mm or more). It can be exemplified that the calcined body of the present embodiment has a warp of more than 0 mm and further of 0.01 mm or more. The warp is preferably 0.06 mm or less, more preferably 0.05 mm or less, and further preferably less than or equal to the measurement limit (less than 0.03 mm).

The warp can be measured by the maximum thickness of the gauge that can be inserted into the gap formed in the state where the convex portion of the calcined body is arranged so as to be in contact with the horizontal plate. FIG. 4 is a schematic view showing a method for measuring warpage. The calcined body (400) shows a cross section of a disk-shaped sample, and shows a calcined body in a state of being warped in the stacking direction (Y-axis direction). In FIG. 4, for the sake of explanation, the warp of the calcined body (400) is emphasized. As shown in FIG. 4, when measuring the warp, the convex portion of the uneven-shaped calcined body (400) is arranged so as to be in contact with the horizontal plate (41). As a result, a gap is formed between the surface (hereinafter, also referred to as “bottom surface”) in which the calcined body (400) and the horizontal plate (41) are in contact with each other and the horizontal plate (41). A gauge is inserted into the gap, and the warp can be measured with the maximum value of the thickness of the inserted gauge. In FIG. 4, the gauge (42A) is located at the lower part of the bottom surface of the calcined body (400) and shows a state where it can be inserted into the gap, while the gauge (42B) is the calcined body (400). It is not located at the bottom of the bottom, indicating that it cannot be inserted into the gap. The gauges (42A) and (42B) in FIG. 4 are gauges having a thickness one step (for example, 0.01 mm) different from each other, and the warp of the calcined body (400) is the thickness of the gauge (42A). For the sake of simplicity of explanation, in FIG. 4, both gauges (42A) and (42B) are inserted, but the warp is measured by inserting the gauges having the thinnest thickness in order from the gap. (For example, after measuring using a gauge (42A), remove it, and then measure using a thicker gauge (42B), etc.).

The calcined body of the present embodiment preferably has a warp (hereinafter, also referred to as “deformation amount”) with respect to the dimensions of the calcined body to be 1.0 or less, more preferably 0.5 or less. It is more preferably 0.2 or less, and further preferably 0.15 or less. It can be exemplified that the amount of deformation is 0 or more, further 0.01 or more, and further 0.05 or more.

The amount of deformation can be calculated from the following equation.
Deformation amount = (warp: mm) / (dimension of calcined body: mm) x 100

The size of the calcined body is the size of the calcined body in the direction perpendicular to the warp direction. Since the calcined body (400) in FIG. 4 is warped in the laminating direction (Y-axis direction), the dimensions of the calcined body (400) are horizontal (X-axis direction) perpendicular to the laminating direction. The size of (43). The dimensions can be measured by a known measuring method using a caliper, a micrometer or the like. For example, in the case of a disk-shaped or columnar laminate, the diameter of the upper end and the diameter of the lower end are measured at four points each using a caliper, and the average value of the diameters of the upper end and the lower end is calculated to obtain the obtained value. The average value may be used as the size of the laminated body.

In the present embodiment, the amount of warpage and deformation is preferably a value measured using a disk-shaped sample as a measurement sample, and a value measured using a disk-shaped sample having a diameter of 5 mm or more and 120 mm or less as a measurement sample. Is more preferable.

The calcined product of the present embodiment comprises a zirconia composition layer containing a zirconia containing a stabilizer and a colorant. The zirconia composition layer is a layer containing zirconia as a main component, and the zirconia is zirconia containing a stabilizer (hereinafter, also referred to as "stabilizer-containing zirconia"). The calcined product and the zirconia composition layer of the present embodiment may contain not only stabilizer-containing zirconia and a colorant but also unavoidable impurities such as hafonia (HfO ₂ ).

The zirconia contained in the calcined product of the present embodiment is preferably in a state in which the zirconia in which the zirconia sol has been heat-treated is heat-treated at a temperature lower than the sintering temperature, and the zirconia sol obtained by hydrolysis of the zirconium compound is heat-treated. It is more preferable that the zirconia is heat-treated at a temperature lower than the sintering temperature, and it is further preferable that the zirconia sol obtained by hydrolyzing zirconium oxychloride is heat-treated at a temperature lower than the sintering temperature.

The stabilizer may have a function of suppressing the phase transition of zirconia. The stabilizer does not contain an element having a function of coloring zirconia, has a function of suppressing a phase transition (hereinafter, also referred to as “non-coloring stabilizer”), and a function of coloring zirconia. At least one of a stabilizer (hereinafter, also referred to as “color stabilizer”) containing an element having the above and having a function of suppressing a phase transition is mentioned, and is a non-color stabilizer and a color stabilizer. It may contain at least a non-coloring stabilizer.

Specific stabilizers include yttrium (Y ₂ O ₃ ), calcia (CaO), magnesia (MgO), ceria (CeO ₂ ), placeodymium oxide (Pr ₆ O ₁₁ ), neodymium oxide (Nd ₂ O ₃ ), One or more selected from the group of terbium oxide (Tb ₄ O ₇ ), erbium oxide (Er ₂ O ₃ ) and ytterbium oxide (Yb ₂ O ₃ ) can be exemplified.

As the non-coloring stabilizer, one or more selected from the group of yttria, calcia, magnesia and ceria can be exemplified, and at least one of yttria and ceria is preferable, and yttria is more preferable.

As the color stabilizer, at least one selected from the group of placeodymium oxide, neodymium oxide, terbium oxide (terbium), erbium oxide (erbium) and itterbium oxide can be exemplified, and at least one of terbium oxide and erbium oxide. Is preferable.

The calcined product of the present embodiment contains at least a stabilizer contained in zirconia, that is, in a state of being solid-solved in zirconia. Further, it is preferable that the calcined product of the present embodiment does not contain an unsolid solution stabilizer, that is, does not contain a stabilizer that is not solid solution in zirconia. In the present embodiment, "not including an undissolved stabilizer" means that an XRD peak derived from the stabilizer is not confirmed in the XRD measurement and the analysis of the XRD pattern described later, and the stabilizer It may be acceptable to include an undissolved stabilizer as long as the XRD peak derived from is not confirmed.

The content of the stabilizer-containing zirconia stabilizer contained in the first composition layer (hereinafter, also referred to as “stabilizer content of the first composition layer”) is 3.3 mol% or more, and 3 It is preferably 5.5 mol% or more, more preferably 3.7 mol% or more, further preferably 4 mol% or more, still more preferably 4.1 mol% or more, and 4.2 mol% or more. Is even more preferable. The stabilizer content of the first composition layer may be 6.0 mol% or less, further 5.8 mol% or less, further 5.5 mol% or less, and further 5.0 mol% or less. Can be mentioned. The stabilizer content of the first composition layer is 3.3 mol% or more and 6.0 mol% or less, 3.5 mol% or more and 5.0 mol% or less, 4 mol% or more and 6.0 mol% or less, and further 4 mol% or more and 5. Less than 0 mol% can be exemplified.

The content of the stabilizer-containing zirconia stabilizer contained in the second composition layer (hereinafter, also referred to as “stabilizer content of the second composition layer”) is the stabilization of the first composition layer. Although it may be different from the agent content, it is preferable that the stabilizer content of the second composition layer is larger than that of the stabilizer content of the first composition layer. That is, it is preferable that the calcined product of the present embodiment does not contain a composition layer in which the content of the zirconia stabilizer is less than 3.3 mol%. As a result, when this is sintered, it becomes easier to obtain a sintered body having a color tone closer to that of natural teeth.

The stabilizer content of the second composition layer may be 1.5 mol% or more, further 2.0 mol% or more, and further 3.0 mol% or more, but 4.0 mol% or more is preferable. It is more preferably more than 0 mol%, further preferably 4.5 mol% or more, further preferably 5.0 mol% or more, and even more preferably more than 5.0 mol%. The stabilizer content of the second composition layer is 7.0 mol% or less, further 6.5 mol% or less, further 6.0 mol% or less, and further 5.8 mol% or less. Can be mentioned. When the content of the stabilizer between the first composition layer and the second composition layer is different and the stabilizer content of both layers is within this range, it is obtained by sintering the calcined body. The sintered body tends to exhibit a texture that can be visually recognized as a texture close to that of natural teeth. The stabilizer content of the second composition layer is 1.5 mol% or more and 7.0 mol% or less, further 3.0 mol% or more and 6.5 mol% or less, and further 3.9 mol% or more and 6.5 mol% or less. Further, 4.5 mol% or more and 6.5 mol% or less, further 5.0 mol% or more and 6.5 mol% or less, and further more than 5.0 mol% and 6.0 mol% or less.

The calcined product of the present embodiment contains at least a first zirconia composition layer and a zirconia composition layer containing zirconia having a stabilizer content of 4.5 mol% or more and further 5 mol% or more. It is preferable to provide the first composition layer, and more preferably to provide a composition layer containing zirconia having a stabilizer content of more than 5 mol%. As another embodiment, the calcined product of the present embodiment has a stabilizer content of the first composition layer of 4.0 mol% or more and 5.1 mol% or less, and contains a stabilizer of the second composition layer. More preferably, the amount is 4.5 mol% or more and 6.0 mol% or less. Further, the stabilizer content of the first composition layer is 3.3 mol% or more and 4.5 mol% or less, and the stabilizer content of the second composition layer is more than 4.5 mol% and 5.8 mol% or less. The stabilizer content of the first composition layer is 3.8 mol% or more and 4.3 mol% or less, and the stabilizer content of the second composition layer is 4.7 mol% or more and 5 It is more preferably 5.5 mol% or less.

The content of the stabilizer-containing zirconia stabilizer contained in the third composition layer (hereinafter, also referred to as “stabilizer content of the third composition layer”) is the first composition layer and the second. The minimum value of the content of the zirconia stabilizer contained in the composition layer and the minimum value of the content of the zirconia stabilizer contained in the first composition layer and the second composition layer. It is preferably exceeded and less than the maximum value. The stabilizer content of the third composition layer is 1.5 mol% or more and 7.0 mol% or less, further 3.0 mol% or more and 6.5 mol% or less, and further 4.0 mol% or more and 6.0 mol% or less. Can be exemplified. The content of the zirconia stabilizer contained in the first composition layer and the second composition layer is 4.0 mol%, and the content of the zirconia stabilizer contained in the second composition layer is 6.0 mol. When it is%, the content of the zirconia stabilizer in the third composition layer is 4.0 mol% or more and 6.0 mol% or less, preferably more than 4.0 mol% and less than 6.0 mol%. Can be mentioned. When the stabilizer content of the third composition layer is the same as the stabilizer content of the first composition layer or the second composition layer, it is the same as the stabilizer content of the third composition layer. The zirconia composition layer having the same stabilizer content and located at the uppermost layer or the lowest layer may be regarded as the first composition layer or the second composition layer.

The difference between the stabilizer content of the first composition layer and the stabilizer content of the second composition layer is preferably 0.2 mol% or more, more preferably 0.5 mol% or more, and 0. It is more preferably 7 mol% or more, further preferably 1.0 mol% or more, and even more preferably 1.2 mol% or more. As the difference in the stabilizer content increases, the difference in color tone between the layers of the sintered body obtained by sintering the stabilizer tends to increase, but the warp may also increase. The difference between the stabilizer content of the first composition layer and the stabilizer content of the second composition layer may be less than 2.5 mol%, further 2.0 mol% or less, and further 1.7 mol% or less. For example, the color tone change of the sintered body obtained by sintering the calcined body of the present embodiment tends to be the same as that of the natural tooth. The difference between the stabilizer content of the first composition layer and the stabilizer content of the second composition layer is 0.7 mol% or more and less than 2.5 mol%, and the warp is 0.5 mm or less. Is more preferable.

In the calcined product of the present embodiment, the difference in the content of the stabilizer between the adjacently laminated zirconia composition layers is 0.5 mol% or more and 3.0 mol% or less, and further 1.0 mol% or more. It is preferable to include a structure having a structure of 5 mol% or less, more preferably 1.2 mol% or more and 2.0 mol% or less.

The content of the stabilizer of the calcined body of the present embodiment (the content of the stabilizer as a whole calcined body) is arbitrary, but for example, it exceeds 1.5 mol% and is less than 7.0 mol%, and further. It is mentioned that it is 2.5 mol% or more and 6.5 mol% or less, further 3.0 mol% or more and 6.0 mol% or less, and further 3.5 mol% or more and 5.8 mol% or less, and 4.1 mol% or more. It is preferably 5.5 mol% or less, more preferably 4.2 mol% or more and 5.0 mol% or less, and even more preferably 4.2 mol% or more and 4.8 mol% or less. The stabilizer content of the calcined body is obtained from the following formula and varies depending on the thickness of each composition layer.

Stabilizer content of calcined body = (layer thickness of first composition layer / height of calcined body) × stabilizer content of first composition layer
+ (Layer thickness of second composition layer / height of calcined body) × Stabilizer content of second composition layer
＋ ・ ・ ・
+ (Layer thickness of nth composition layer / height of calcined body) × Stabilizer content of nth composition layer Because the stabilizer content of the first composition layer is 3.3 mol% or more. For example, when the stabilizer content of the second composition layer is more than 3.3 mol%, the stabilizer of the calcined body is provided with two composition layers having the same layer thickness. The content is more than 3.3 mol%.

In the calcined product of the present embodiment, the stabilizer content of the first composition layer is 3.3 mol% or more and 5.0 mol% or less, and the stabilizer content of the second composition layer is 4.6 mol%. The difference between the stabilizer content of the first composition layer and the stabilizer content of the second composition layer is 0.7 mol% or more and 1.8 mo% or less. The yttria content of the first composition layer is 3.8 mol% or more and 4.5 mol% or less, and the yttria content of the second composition layer is more than 5.0 mol% and 5.5 mol% or less. Moreover, it is more preferable that the difference between the yttria content of the first composition layer and the yttria content of the second composition layer is 1.0 mol% or more and 1.6 mo% or less.

In the present embodiment, the content of the stabilizer is the molar ratio of the stabilizer to the total of zirconia and the stabilizer. In calculating the content of the stabilizer, the content of each stabilizer may be obtained in terms of the above-mentioned oxide. For example, when yttria and ervia are included as stabilizers, the content (mol%) of the stabilizer is (Y ₂ O ₃ + Er ₂ O ₃ ) / (ZrO ₂ + Y ₂ O ₃ + Er ₂ O ₃ ) × 100. Is required from.

The colorant in this embodiment is an element having a function of coloring zirconia. As a specific colorant, at least one of a transition metal element and a lanthanoid-based rare earth element can be exemplified, and preferably iron (Fe), cobalt (Co), nickel (Ni), manganese (Mn), praseodymium (Pr). , Neogym (Nd), Europium (Eu), Gadolium (Gd), Terbium (Tb), Erbium (Er) and Itterbium (Yb), more preferably one or more, more preferably iron, cobalt, manganese, praseodymium. , One or more selected from the group of gadium, terbium and erbium, and more preferably one or more selected from the group of iron, cobalt, terbium and erbium.

The colorant contained in the calcined body of the present embodiment is a colorant contained in an oxide state (hereinafter, also referred to as “oxide colorant”) and a colorant contained in a solid solution state in zirconia. It may be at least one of. Preferred oxide colorants include one or more selected from the group of iron, cobalt, nickel and manganese, and more preferably at least one of iron and cobalt. The calcined body of the present embodiment may contain two or more kinds of colorants, and may contain, for example, two or more and five or less colorants, and further three or more and four or less kinds of colorants. The calcined product of the present embodiment preferably contains at least a color stabilizer, more preferably at least one of terbium and erbium, and further preferably at least terbium and erbium.

The types and contents of the colorants contained in each composition layer are equal. Therefore, it is not necessary to change the content of the colorant in each layer when producing the calcined product. In addition to this, since the types of colorants contained are the same, a natural color tone change can be imparted by the sintered body obtained by sintering the gradations of similar colors and the like. In addition, "equal content of colorant" in this embodiment means that the content of colorant between layers is equal to the extent that the effect of the calcined body of this embodiment can be exhibited, and the color tone of the sintered body is equal. The difference in the content of the colorant is acceptable, and the difference in the content of the colorant does not cause a difference in the sintering behavior due to the difference in the content of the colorant between the layers in the manufacturing process.

The content of the colorant in the calcined product of the present embodiment is more than 0% by mass and 1.5% by mass or less, preferably 1.5% by mass or less, as the mass ratio of the colorant in terms of oxide to the mass of the calcined product of the present embodiment. It is 0.01% by mass or more and 1.0% by mass or less, more preferably 0.03% by mass or more and 0.8% by mass or less, and further preferably 0.04% by mass or more and 0.3% by mass or less. For example, when yttria (non-coloring stabilizer) and elvia (coloring stabilizer) are contained as stabilizers, and alumina and cobalt (oxide colorant) are contained, the content of the colorant (mass%). ) Is obtained from (Co ₃ O ₄ + Er ₂ O ₃ ) / (ZrO ₂ + Y ₂ O ₃ + Er ₂ O ₃ + Co ₃ O ₄ + Al ₂ O ₃ ) × 100. The oxide conversion of the colorant is Pr ₆ O ₁₁ for placeodymium oxide, Nd ₂ O _{3 for} neodymium oxide, Tb ₄ O _{7 for} terbium oxide, Er ₂ O _{3 for} erbium oxide and Yb ₂ O _{3 for} ytterbium oxide, and iron for iron. Fe ₂ O ₃ and cobalt may be Co ₃ O ₄ , nickel may be NiO, and manganese may be Mn ₃ O ₄ .

Each composition layer has the same colorant content. Therefore, the content of the colorant contained in each composition layer, that is, the mass ratio of the colorant contained in each composition layer in terms of oxide with respect to the mass of each composition layer, is the coloring of the above-mentioned calcined body. Equal to the content of the agent.

The calcined product of the present embodiment may contain alumina, and it is preferable that at least one zirconia composition layer contains alumina. The alumina content of the calcined product of the present embodiment may be 0% by mass or more, 0% by mass or more and 0.15% by mass or less, as a ratio of the weight of alumina to the weight of the calcined product. It can be mentioned that it is 0% by mass or more and 0.10% by mass or less, and further 0% by mass or more and 0.07% by mass or less. When alumina is contained, the alumina content is more than 0% by mass and 0.15% by mass or less, preferably 0.005% by mass or more and 0.10% by mass or less, and more preferably 0.01% by mass or more and 0.70% by mass. % Or less.

It can be exemplified that the alumina content of each zirconia composition layer is also in the same range as described above. The alumina content of each zirconia composition layer may affect the heat shrinkage behavior of the calcining stage. The alumina content of each zirconia composition layer is arbitrary, and each zirconia composition layer may have a different alumina content, but preferably has the same alumina content. When the alumina contents of the zirconia composition layers are different, the difference in the alumina contents of the adjacent zirconia composition layers is more than 0% by mass and 1.0% by mass or less, and further more than 0% by mass and 0.5% by mass. Hereinafter, it can be exemplified that it is more than 0% by mass and 0.03% by mass or less, and further more than 0.005% by mass and 0.01% by mass or less. For example, in the case of a zirconia layer containing alumina (Al ₂ O ₃ ) and composed of zirconia in which the non-coloring stabilizer is ytria (Y ₂ O ₃ ) and the coloring stabilizer is ervia (Er ₂ O ₃ ), alumina. The content can be determined as {Al ₂ O ₃ / (ZrO ₂ + Y ₂ O ₃ + Er ₂ O ₃ + Al ₂ O ₃ )} × 100 (mass%).

It is preferable that the calcined product of the present embodiment substantially does not contain either silica or titania.

It is more preferable that the calcined product of the present embodiment contains at least a zirconia composition layer containing zirconia having a tetragonal crystal or a cubic crystal as a main phase. The "main phase" in the present embodiment means the crystal phase having the largest abundance ratio (ratio of integrated intensity of peaks) among the crystal phases of zirconia. The abundance ratio can be obtained from the XRD pattern on the surface of the calcined body.

The following conditions can be exemplified as the measurement conditions for the XRD pattern on the surface of the calcined body.
Source: CuKα ray (λ = 1.541862Å)
Measurement mode: Step scan Scan condition: 0.000278 ° / s
Measurement range: 2θ = 10-140 °
Irradiation width: constant (10 mm)

The obtained XRD pattern may be subjected to Rietveld analysis, the ratio of tetragonal crystals and cubic crystals (ratio of integrated intensity of peaks) may be obtained, and the crystal phase having a high ratio may be used as the main phase. The measurement of the XRD pattern and the Rietveld analysis can be performed by a general-purpose powder X-ray diffractometer (for example, X'pert PRO MPD, manufactured by Spectris) and analysis software (for example, RIETAN-2000).
The calcined body of the present embodiment has an example in which the density is 2.4 g / cm ³ or more and 3.7 g / cm ³ or less, preferably 3.1 g / cm ³ or more and 3.5 g / cm ³ or less. it can. Densities in this range correspond to relative densities of 40% to 60%. The calcined body has strength suitable for processing such as CAD / CAM processing.

The density of the calcined body is obtained from the weight obtained by weight measurement and the volume obtained by dimensional measurement.

The color tone of the composition layer contained in the calcined product may be different from that of the sintered body obtained by sintering the composition layer, and the color tone may not change.

The calcined body and each composition layer of the present embodiment are opaque, and the total light transmittance (hereinafter, also simply referred to as “total light transmittance”) with respect to the CIE standard light source D65 at a sample thickness of 1.0 mm is 0%. However, when the measurement error is taken into consideration, it can be exemplified that the total light transmittance is 0% or more and 0.2% or less.

The total light transmittance is measured by a method according to JIS K 7361, and can be obtained as a value of the transmittance which is the sum of the diffuse transmittance and the linear transmittance for the incident light, using the CIE standard light source D65 as the incident light. Using a sample with a thickness of 1 mm and a surface roughness (Ra) ≤ 0.02 μm as a measurement sample, irradiate the sample with a CIE standard light source D65 using a general turbidity meter, and collect the transmitted light with an integrating sphere. Therefore, the transmittance of the sample (diffuse transmittance and linear transmittance) is measured, and this may be used as the total light transmittance.

The calcined body of the present embodiment may have enough strength to prevent defects from occurring during processing such as CAD / CAM and cutting.

The calcined body of the present embodiment can be used for known zirconia applications such as structural materials and optical materials, but can be suitably used as a precursor of dental materials such as dentures such as crowns and bridges. , Blanks, discs, blocks and the like can be used as dental prosthetic materials. In addition, it can be a dental material containing the calcined body of the present embodiment.

Next, a method for producing the calcined body of the present embodiment will be described.

The manufacturing method of this embodiment is
A colorant having a structure in which two or more powder composition layers composed of a powder composition containing zirconia containing a stabilizer, a colorant, and a binder are laminated, and the colorant contained in each powder composition layer. And their contents are equal to each other, at least
A first powder composition layer containing zirconia having a stabilizer content of 3.3 mol% or more, a colorant, and a binder.
A second powder composition layer containing zirconia and a stabilizer contained in the first powder composition layer having different contents, a colorant, and a binder.
With
A step of calcining a molded product in which the difference in the content of the binder between the first powder composition layer and the second powder composition layer exceeds 0.01% by mass at 800 ° C. or higher and lower than 1200 ° C. It is a method for producing a calcined body, which is characterized by having.

The molded product used in the manufacturing method of the present embodiment is
A colorant having a structure in which two or more powder composition layers composed of a powder composition containing zirconia containing a stabilizer, a colorant, and a binder are laminated, and the colorant contained in each powder composition layer. And their contents are equal to each other, at least
A first powder composition layer containing zirconia having a stabilizer content of 3.3 mol% or more, a colorant, and a binder.
A second powder composition layer containing zirconia and a stabilizer contained in the first powder composition layer having different contents, a colorant, and a binder.
With
A molded product in which the difference in the content of the binder between the first powder composition layer and the second powder composition layer exceeds 0.01% by mass.

It is known that a powder composition containing a binder improves the cohesive strength of zirconia and suppresses the occurrence of defects such as cracks and chips during molding. In order to make the strength of the obtained molded product uniform, it is usually necessary to make the content of the binder in the powder composition used for producing the molded product uniform. On the other hand, in the molded product of the present embodiment, the binder not only improves the strength of the molded product, but also suppresses the generation of stress between the laminated layers by differentiating the content of the binder between the layers. Is thought to play different functions as well. As a result, it is considered that the molded product composed of a laminated body in which powder compositions containing zirconia having different stabilizer contents are laminated with each other while suppressing deformation during molding can be heat-treated without causing excessive defects. ..

The molded body used in the manufacturing method of the present embodiment will be described below with respect to the main points different from the above-mentioned calcined body.

The molded product used in the manufacturing method of the present embodiment is
A colorant having a structure in which two or more powder composition layers composed of a powder composition containing zirconia containing a stabilizer, a colorant, and a binder are laminated, and the colorant contained in each powder composition layer. And their contents are equal to each other, at least
A first powder composition layer containing zirconia having a stabilizer content of 3.3 mol% or more, a colorant, and a binder.
A second powder composition layer containing zirconia and a stabilizer contained in the first powder composition layer having different contents, a colorant, and a binder.
With
A molded product in which the difference in the content of the binder between the first powder composition layer and the second powder composition layer exceeds 0.01% by mass.

The molded body is a composition having a multi-layer structure, a so-called laminate, and is a laminate composed of a powder composition. The molded body can be provided as a precursor of a calcined body or a sintered body.

The molded body is a powder composition layer (hereinafter, also referred to as “powder layer”) composed of a powder composition containing a zirconia containing a stabilizer, a colorant, and a binder instead of having a zirconia composition layer. ), And has a structure equivalent to the laminated structure shown in FIG. 2 or FIG. Therefore, the molded product can be regarded as a laminate having two or more layers containing a zirconia powder containing a stabilizer and a binder. In the molded product, the stabilizer and the colorant may be in a solid solution state in zirconia, or may be in a state of an oxide or a precursor thereof. As a precursor, one or more selected from the group of sulfides, chlorides, nitrates, sulfates, hydroxides and oxyhydroxylates, and further selected from the group of chlorides, hydroxides and oxyhydroxides 1 The above can be exemplified. Further, the colorant preferably contains at least an oxide.

The warp of the molded product is preferably 1.0 mm or less, more preferably 0.3 mm or less, further preferably 0.2 mm or less, still more preferably 0.1 mm or less. Even more preferably, it is 0.05 mm or less. The molded product preferably has no warp (warp is 0 mm), but may have a warp that cannot be measured by a gauge (warp is 0 mm or more). It can be exemplified that the warpage of the molded product exceeds 0 mm and further 0.01 mm or more. The warp is preferably 0.06 mm or less, more preferably 0.05 mm or less, and further preferably less than or equal to the measurement limit (less than 0.03 mm).
The amount of deformation of the molded product is preferably 1.0 or less, more preferably 0.5 or less, more preferably 0.2 or less, and further preferably 0.15 or less. It can be exemplified that the amount of deformation is 0 or more, further 0.01 or more, and further 0.05 or more.

The zirconia contained in the powder layer is preferably zirconia in which the zirconia sol is heat-treated, more preferably the zirconia sol obtained by hydrolysis of the zirconium compound is heat-treated zirconia, and zirconium oxychloride is hydrolyzed. It is more preferable that the resulting zirconia sol is heat-treated zirconia.

The zirconia contained in the powder layer is preferably zirconia powder. The average particle size of the zirconia powder is preferably 0.3 μm or more and 0.7 μm or less, and preferably 0.4 μm or more and 0.5 μm or less.

The colorant contained in the powder layer is preferably at least one in a state of being mixed with the zirconia powder and a state of being solid-solved in zirconia. Further, the colorant powder and the zirconia powder may be mixed.

The binder contained in the powder layer is preferably a binder that vaporizes at 1200 ° C. or lower, more preferably an organic binder, and an organic bond that has fluidity at room temperature (for example, 10 ° C. to 30 ° C.). It is more preferably an agent. Further, the binder does not have to contain a plasticizer or a mold release agent. As the organic binder, one or more selected from the group of polyvinyl alcohol, polyvinyl butyrate, wax and acrylic resin, preferably one or more of polyvinyl alcohol and acrylic resin, and more preferably acrylic resin. In the present embodiment, the acrylic resin is a polymer containing at least one of an acrylic acid ester and a methacrylic acid ester. The acrylic resin contained in the powder composition may be any one used as a binder for ceramics. Specific examples of the acrylic resin include one or more selected from the group of polyacrylic acid, polymethacrylic acid, acrylic acid copolymers and methacrylic acid copolymers, and derivatives thereof.

The content of the stabilizer-containing zirconia stabilizer contained in the first powder layer (hereinafter, also referred to as "first powder layer"), the second powder layer (hereinafter, also referred to as "second powder layer"). The content of the stabilizer-containing zirconia stabilizer contained in) and the stabilizer-containing zirconia stabilizer contained in the third powder layer (hereinafter, also referred to as “third powder layer”). The content of the stabilizer may be the same as the stabilizer content of the first layer, the second layer and the third layer, respectively.

The content of the stabilizer and the colorant of the molded product and each powder layer is arbitrary, but may be the same as that of the calcined product of the present embodiment described above.

From the viewpoint of suppressing defects during molding, the content of the binder in each powder layer is preferably 1.5% by mass or more, and more preferably 1.5% by mass or more and 8.0% by mass or less. It is more preferably 2.0% by mass or more and 6.0% by mass or less, and even more preferably 2.5% by mass or more and 5.5% by mass or less.

In the molded product, the difference in the content of the binder between the first powder layer and the second powder layer (hereinafter, also referred to as “difference in the amount of the binder”) exceeds 0.01% by mass and 0.03% by mass. The above is preferable. As described above, the molded product has a different content of the binder between the first powder layer and the second powder layer. As a result, stress generation during molding is suppressed. From the viewpoint of suppressing the generation of stress, the difference in the amount of the binder is more than 0.01% by mass and 5% by mass or less, and more preferably 0.03% by mass or more and 3.5% by mass or less, preferably 0. 04% by mass or more and 3% by mass or less, more preferably 0.05% by mass or more and 2% by mass or less, still more preferably 0.06% by mass or more and 1.5% by mass or less, still more preferably 0.07% by mass or more 1 It is mass% or less. In another embodiment, the difference in the amount of binder is 0.01% by mass or more and 0.5% by mass or less, further 0.02% by mass or more and 0.3% by mass or less, and further 0.03% by mass or more and 0. 1% by mass or less, and the like.

The content of the binder is the weight ratio of the binder to the weight of the powder composition in the powder layer excluding the binder ({cinder / (powder composition-binder)} × 100), and the powder composition. In the production of a product, the total mass of the constituent components (for example, oxide-converted stabilizer, zirconia and alumina) of the powder composition other than the binder is determined, and then the mass ratio of the target binder to this is determined. , Producing a powder composition.

In order to suppress the warp of the molded product, it is preferable to adjust the content of the binder in each powder layer according to the content of the stabilizer in the adjacent powder layer. The first powder layer and the second powder layer have a higher content of stabilizers and binders than the first powder layer.
The content of the stabilizer and the binder is smaller in the second powder layer than in the first powder layer.
The second powder layer has a higher content of stabilizer and a lower content of binder than the first powder layer, and the second powder layer has a higher content of stabilizer than the first powder layer. It can be exemplified that the content is low and the content of the binder is high.
The second powder layer has a higher content of stabilizer and a lower content of binder than the first powder layer, or the second powder layer has a higher content of stabilizer than the first powder layer. It is preferable that the content is low and the content of the binder is high. The contents of the stabilizer and the binder may be different between the first powder layer and the second powder layer, but the warp of the molded product tends to be suppressed, so that the difference in the amount of the binder may be large. It is preferable that one of the first powder layer and the second powder layer has a lower content of the stabilizer and a higher content of the binder than the other powder layer. ..

Further, in the powder layers laminated adjacent to each other, it is preferable that one powder layer containing zirconia having a low stabilizer content has a higher binder content than the other powder layer. Further, when the powder layers are laminated adjacent to each other and the zirconia contained in one of the powder layers is a mixture of two or more zirconia having different stabilizer contents, the stabilizer is used. It is preferable that one powder layer containing zirconia having a low content of zirconia has a lower binder content than the other powder layer.

From the viewpoint of operability, the powder composition contained in the powder layer is preferably a powder in which a zirconia powder, a colorant and a binder are granulated (hereinafter, also referred to as “granulated powder”), and is sprayed. It is more preferable that the granulated powder (hereinafter, also referred to as “powder granules”) is granulated into granules by drying or the like.

The particle size of the granulated powder is arbitrary, and examples thereof include an average aggregate diameter of 1 μm or more and 150 μm or less, preferably 1 μm or more and 100 μm or less, more preferably 5 μm or more and 50 μm or less, and further preferably 5 μm or more and 30 μm or less. As another embodiment, 20 μm or more and 50 μm or less can be exemplified.

In the present embodiment, the average agglomeration diameter is a diameter corresponding to a cumulative 50% in the volume particle size distribution measurement. The volume particle size distribution is a value that can be measured by a general-purpose device (for example, MT3100II, manufactured by Microtrac Bell), and is a volume diameter of particles that approximate a sphere.

It is more preferable that the molded product contains at least a powder layer containing zirconia having a tetragonal crystal or a cubic crystal as a main phase.

It can be exemplified that the molded body has a density of 2.4 g / cm ³ or more and 3.7 g / cm ³ or less, preferably 3.1 g / cm ³ or more and 3.5 g / cm ³ or less. Densities in this range correspond to relative densities of 40% to 60%.

The density of the molded product is obtained from the weight obtained by weight measurement and the volume obtained by dimensional measurement.

The color tone of the zirconia layer contained in the molded product may be different from that of the sintered body obtained by sintering the zirconia layer, and the color tone may not change.

The molded body and each powder layer are opaque and the total light transmittance is 0%, but when the measurement error is taken into consideration, it can be exemplified that the total light transmittance is 0 or more and 0.2% or less.

The molded product may have enough strength to prevent cracking or chipping during calcining or sintering.

A molded product is obtained by laminating a powder composition and molding the powder composition. Each powder composition is obtained by mixing the zirconia powder and the binder in a desired ratio by a known method. The molding is preferably pressure molding. For example, a powder composition having a composition corresponding to the bottom layer is filled in a molding mold to form a bottom layer. Then, a powder composition having a composition corresponding to the composition of the layer adjacent to the bottom layer is filled on the bottom layer. In the case of forming a molded product having a structure in which three or more powder layers are laminated, the same operation may be repeated to laminate the necessary powder compositions. After filling a powder composition having a composition corresponding to the composition of the uppermost layer, uniaxial pressure molding is performed at an arbitrary pressure to obtain a preformed body, which is also referred to as a cold hydrostatic press (hereinafter, also referred to as “CIP”). ) By processing, a molded product can be obtained. At the time of stacking, it is not necessary to apply vibration that forms a mixed layer between layers, such as vibration using a vibrator. Further, the uniaxial pressure molding is preferably performed after filling the powder composition having the composition corresponding to the uppermost layer, and the pressurization should not be performed before filling the powder composition having the composition corresponding to the uppermost layer. preferable.

The molding pressure for uniaxial pressure molding is preferably 15 MPa or more and 200 MPa or less, and more preferably 18 MPa or more and 100 MPa or less. In uniaxial pressure molding, the warpage of the molded product tends to be suppressed as the molding pressure increases. The pressure of the CIP treatment includes a molding pressure of 98 MPa or more and 392 MPa or less.

By treating the molded body at a temperature lower than the sintering temperature, the molded body becomes a calcined body. A known method can be used for the calcining method and the calcining conditions.

The holding temperature at the time of calcining (hereinafter, also referred to as “temporary firing temperature”) is 800 ° C. or higher and 1200 ° C. or lower, preferably 900 ° C. or higher and 1150 ° C. or lower, and more preferably 950 ° C. or higher and 1100 ° C. or lower.

The holding time at the calcination temperature (hereinafter, also referred to as “temporary calcination time”) is preferably 0.5 hours or more and 5 hours or less, and more preferably 0.5 hours or more and 3 hours or less.

The atmosphere in the calcining step (hereinafter, also referred to as “temporary firing atmosphere”) is preferably an atmosphere other than the reducing atmosphere, more preferably at least one of an oxygen atmosphere and an air atmosphere, and in the air atmosphere. It is more preferable to have.

In the production method of the present embodiment, either a molded product or a calcined product (hereinafter, these are collectively referred to as “molded product or the like”) is treated at a temperature of more than 1200 ° C. and 1600 ° C. or lower. As a result, the molded product or the like becomes a sintered body. Prior to sintering, the molded product or the like may be processed into an arbitrary shape.

A known method can be used as the sintering method and sintering conditions. As the sintering method, at least one selected from the group of atmospheric pressure sintering, HIP treatment, SPS and vacuum sintering can be mentioned. Since it is widely used as an industrial sintering method, the sintering method is preferably normal pressure sintering, and more preferably normal pressure sintering in an air atmosphere. The sintering method is preferably only normal pressure sintering, and more preferably no pressure sintering after normal pressure sintering. As a result, the sintered body can be obtained as a normal pressure sintered body. In the present embodiment, normal pressure sintering is a method of sintering by simply heating the object to be sintered without applying an external force at the time of sintering.

The holding temperature during sintering (hereinafter, also referred to as “sintering temperature”) is 1200 ° C. or higher and 1600 ° C. or lower, preferably 1300 ° C. or higher and 1580 ° C. or lower, more preferably 1400 ° C. or higher and 1560 ° C. or lower, and further preferably. It is 1430 ° C. or higher and 1560 ° C. or lower, and even more preferably 1480 ° C. or higher and 1560 ° C. or lower. In another embodiment, the sintering temperature is 1450 ° C. or higher and 1650 ° C. or lower, preferably 1500 ° C. or higher and 1650 ° C. or lower, and more preferably 1550 ° C. or higher and 1650 ° C. or lower.

The rate of temperature rise to the sintering temperature is 50 ° C./hour or more and 800 ° C./hour or less, preferably 100 ° C./hour or more and 800 ° C./hour or less, more preferably 150 ° C./hour or more and 800 ° C./hour or less. More preferably, it is 150 ° C./hour or more and 700 ° C./hour or less.

The holding time at the sintering temperature (hereinafter, also referred to as “sintering time”) varies depending on the sintering temperature, but is preferably 1 hour or more and 5 hours or less, more preferably 1 hour or more and 3 hours or less, and further preferably. It is 1 hour or more and 2 hours or less.

The sintering atmosphere (hereinafter, also referred to as “sintering atmosphere”) is preferably an atmosphere other than the reducing atmosphere, more preferably at least one of an oxygen atmosphere and an atmospheric atmosphere, and is an atmospheric atmosphere. Is even more preferable. It can be exemplified that the atmospheric atmosphere is mainly composed of nitrogen and oxygen, and the oxygen concentration is about 18 to 23% by volume.

Preferable sintering conditions in the sintering step include atmospheric pressure sintering in an air atmosphere.

By sintering the calcined body of the present embodiment, this becomes a sintered body. The sintered body obtained by sintering the calcined body of the present embodiment will be described below with respect to the main points different from the above-mentioned calcined body.

The sintered body is
It has a structure in which two or more layers of zirconia containing a stabilizer and a zirconia layer containing a colorant are laminated, and the colorants and their contents contained in each zirconia layer are equal to each other, at least.
A zirconia having a stabilizer content of 4 mol% or more, a first zirconia layer containing a colorant, and the like.
A second zirconia layer containing a zirconia contained in the first zirconia layer and a zirconia having a different content of a stabilizer, and a colorant.
It is a sintered body, characterized in that it is provided with.

The sintered body is a composition having a multilayer structure, a so-called laminated body, and is a laminated body having a sintered structure. In the present embodiment, the sintered structure is a structure composed of zirconia in the late stage of sintering.

The sintered body has a zirconia layer containing zirconia containing a stabilizer (hereinafter, also simply referred to as “zirconia layer”) instead of having a zirconia composition layer, and the laminate shown in FIG. 2 or FIG. It has a structure equivalent to that of the structure. In the sintered body, the stabilizer is in a state of being contained in zirconia and in a state of being solid-solved in zirconia. Further, it is preferable that the sintered body does not contain an undissolved stabilizer, that is, it does not contain a stabilizer that is not solid-solved in zirconia.

The warpage of the sintered body is preferably 1.0 mm or less, more preferably 0.3 mm or less, further preferably 0.2 mm or less, and even more preferably 0.1 mm or less. , 0.05 mm or less is even more preferable. The sintered body preferably has no warp (warp is 0 mm), but may have a warp that cannot be measured by a gauge (warp is 0 mm or more). It can be exemplified that the warp of the sintered body exceeds 0 mm and further 0.01 mm or more. The warp is preferably 0.06 mm or less, more preferably 0.05 mm or less, and further preferably less than or equal to the measurement limit (less than 0.03 mm).

The amount of deformation of the sintered body is preferably 1.0 or less, more preferably 0.5 or less, more preferably 0.2 or less, and further preferably 0.15 or less. .. It can be exemplified that the amount of deformation is 0 or more, further 0.01 or more, and further 0.05 or more.

The zirconia contained in the sintered body is preferably zirconia in which the zirconia sol heat-treated is sintered, and the zirconia obtained by hydrolyzing the zirconium compound is sintered by the heat-treated zirconia. It is more preferable that the zirconia is in a state, and it is further preferable that the zirconia sol obtained by hydrolyzing zirconium oxychloride is zirconia in a sintered state.

The zirconia contained in the zirconia layer may be sintered zirconia, that is, zirconia crystal particles.

The content of the stabilizer-containing zirconia stabilizer contained in the first zirconia layer (hereinafter, also referred to as "first layer"), the second zirconia layer (hereinafter, also referred to as "second layer"). The content of the stabilizer-containing zirconia stabilizer contained in the above, and the content of the stabilizer-containing zirconia stabilizer contained in the third zirconia layer (hereinafter, also referred to as “third layer”). May be the same as the stabilizer content of the first composition layer, the second composition layer, and the third composition layer, respectively.

The content of the stabilizer in the sintered body and each zirconia layer is arbitrary, but it may be the same as the calcined body of the present embodiment described above.

The sintered body preferably contains at least a zirconia layer containing zirconia having a crystal phase of at least one of a cubic (T phase) and a cubic (C phase), and at least a zirconia having a rectangular main phase. It is more preferable to include a zirconia layer containing zirconia, and it is further preferable to include a zirconia layer containing zirconia having a cubic main phase and a zirconia layer containing zirconia having a cubic main phase.

The density of the sintered body measured by a method according to JIS R 1634 is 5.7 g / cm ³ or more and 6.3 g / cm ³ or less, preferably 5.9 g / cm ³ or more and 6.1 g / cm ³ The following can be exemplified. The density in this range corresponds to 99% or more as a relative density, and is a density that becomes a so-called dense sintered body having practical strength.

The color tone of the sintered body and the zirconia layer is such that the brightness L ^* represented by the L ^* a ^* b ^* color system is 60 or more and 90 or less, preferably 76.5 or more and 85 or less, and the hue a ^* is -5 or more and 15 or less. Hereinafter, it can be exemplified that the hue b ^* is preferably -3 or more and 10 or less, and the hue b ^* is 0 or more and 45 or less, preferably 3 or more and 35 or less. When the color tone is in this range, the sintered body exhibits a color tone similar to that of natural teeth.

Since the sintered body has a change in color tone, it is preferable that the uppermost layer and the lowermost layer have different saturations C ^* . Saturation C ^* is an index showing vividness, and from the hues a ^* and b ^* shown in the L ^* a ^* b ^* color system, C ^* = {(a ^* ) ² + (b ^* ) ² } ^{0 Obtained} from ^.5 . The absolute value (ΔC ^* ) of the difference between the saturation C ^* of the top layer and the bottom layer is 0.1 or more and 15.0 or less, and further 0.3 or more and 10.0 or less, and further 1.0. For example, it is 5.0 or more and 3.0 or less, and further 1.5 or more and 3.0 or less. When ΔC ^* is in this range, it can be visually recognized as a laminated body having a gradation of vividness close to that of natural teeth. Similarly, it can be exemplified that the absolute value (ΔL ^* ) of the difference between the brightness L ^* of the uppermost layer and the lowermost layer is 1.0 or more and 15.0 or less, and further 1.5 or more and 5.0 or less.

The color tones (L ^* , a ^* and b ^* ) and C ^* are the values measured by the SCI method using a spectrophotometer equipped with an illumination / light receiving optical system that conforms to the geometric condition c of JIS Z 8722. Can be used and sought. As a spectrophotometer, for example, CM-700d manufactured by Konica Minolta can be exemplified. As specific measurement conditions for color tone and C ^* , the following conditions can be exemplified in a method of arranging a measurement sample on a black plate for measurement (so-called black background measurement).
Light source: D65 light source Viewing angle: 10 °
Measurement method: SCI

The sintered body preferably contains at least a zirconia layer having a translucent feeling. Further, it is preferable to have at least a zirconia layer having a total light transmittance of 30% or more and 50% or less, further 32% or more and 45% or less, and further 35% or more and 42% or less.

In the sintered body, the difference in the total light transmittance of the zirconia layers laminated adjacently is preferably 1% or more and 10% or less, and more preferably 1% or more and 5% or less.

The total light transmittance of the sintered body is preferably 30% or more and 50% or less, more preferably 32% or more and 45% or less, and further preferably 35% or more and 42% or less. The total light transmittance of the sintered body may be measured as a measurement sample obtained by cutting out an arbitrary portion of the sintered body in the horizontal direction and processing the sample so as to have a sample thickness of 1 mm. The wavelength of light absorbed by the sintered body differs depending on its coloration. Therefore, as an index of translucency, the total light transmittance for light containing different wavelengths, such as the CIE standard light source D65, is suitable.

The sintered body preferably has a three-point bending strength of 500 MPa or more, more preferably 550 MPa or more, and more preferably 600 MPa or more, as measured by a method according to JIS R 1601. It can be exemplified that the three-point bending strength is less than 1100 MPa and further 1000 MPa or less.

FIG. 5 is a schematic view showing the measurement of the three-point bending strength of the sintered body (500) composed of two zirconia layers. The sintered body (500) is shown as a sintered body having a structure in which two zirconia layers having different layer thicknesses are laminated. In FIG. 5, the stacking direction is shown in the X-axis direction and the horizontal direction is shown in the Y-axis direction. The measurement sample used for measuring the three-point bending strength is a rectangular parallelepiped-shaped sintered body produced with the width and thickness in the stacking direction and the length in the horizontal direction. The dimensions of the measurement sample are width 4 mm, thickness 3 mm and length 45 mm. As shown in FIG. 5, the three-point bending strength may be measured by applying a load (51) so as to be perpendicular to the length of the measurement sample (500). The measurement sample may be arranged so that the load (51) is applied in the middle of the distance between the fulcrums (52). The distance between the fulcrums is 30 mm.

The sintered body can be used for known zirconia applications such as structural materials and optical materials, but can be suitably used as a dental material for dentures such as crowns and bridges, and dentistry containing the sintered body. It can be used as a material.

Hereinafter, the calcined body of the present embodiment will be described with reference to Examples. However, the present disclosure is not limited to these examples.
(Warp and deformation amount)
Using a disk-shaped molded body, calcined body, or sintered body as a measurement sample, the amount of deformation of each was calculated from the following formula.
Deformation amount = (warp: mm) / (dimensions: mm) x 100

The warp was measured by the measuring method shown in FIG. The measurement sample was arranged so that the convex portion of the measurement sample was in contact with the horizontal plate. A feeler gauge (product name: 75A19, manufactured by Nagai Gauge Mfg. Co., Ltd.) conforming to JIS B 7524: 2008 was inserted into the gap formed between the horizontal plate and the bottom surface, and the warp was measured. For measurement, a gauge placed parallel to the horizontal plate is inserted into a gap formed between the horizontal plate and the bottom surface of the measurement sample, and the gauge thickness that is the maximum thickness of the gauge that can be inserted into the gap is measured. The gauge thickness was set to warp. The warpage was measured sequentially in increments of gauge thickness 0.03 mm to 0.01 mm by using a single gauge or a combination of gauges.
As for the dimensions of the measurement sample, the diameter of the upper end and the diameter of the lower end were measured at four points each using a caliper, and the average value of the diameters of the upper and lower ends was obtained.

(Total light transmittance)
The total light transmittance of the sample was measured by a method according to the method of JIS K 7361. The total light transmittance was measured by irradiating the measurement sample with the standard light source D65 and detecting the luminous flux transmitted through the measurement sample with an integrating sphere. A general haze meter (device name: haze meter NDH2000, manufactured by NIPPON DENSOKU) was used for the measurement.
A disk-shaped sample was used as the measurement sample, and both sides of the sample were mirror-polished prior to the measurement so that the sample thickness was 1 mm and the surface roughness (Ra) was 0.02 μm or less.

(Average agglomeration diameter)
The average agglomeration diameter was measured by putting a powder granule sample into a Microtrack particle size distribution meter (device name: MT3100II, manufactured by Microtrack Bell). The particle diameter at which the cumulative volume was 50% was defined as the average aggregation diameter.

(Crystal phase)
The crystal phase of the laminated sample was measured by XRD measurement under the following conditions. As a measuring device, a general XRD device (device name: X'pert PRO MPD, manufactured by Spectris) was used.
Source: CuKα ray (λ = 1.541862Å)
Measurement mode: Step scan Scan condition: 0.000278 ° / s
Measurement range: 2θ = 10-140 °
Irradiation width: constant (10 mm)
Rietveld analysis of the obtained XRD pattern was performed using analysis software (RIETAN-2000) to determine the ratio of tetragonal and cubic crystals (ratio of integrated peak intensity), and the crystal phase with a high ratio was used as the main phase. ..

(△ L ^* and △ C ^* )
The color tone was measured using a general spectrophotometer (device name: CM-700d, manufactured by Konica Minolta). The measurement conditions are as follows.
Light source: D65 light source Viewing angle: 10 °
Measurement method: SCI
As the sintered body sample, a disk-shaped sample having a diameter of 20 mm and a thickness of 5.6 mm was used for the examples, and a disk-shaped sample having a diameter of 20 mm and a thickness of 2.8 mm was used for the reference example. Both surfaces of the sintered sample were mirror-polished. The measurement sample was placed on a black plate, and both surfaces after polishing were used as evaluation surfaces, and the color tones (L ^* , a ^* and b ^* ) were measured (black background measurement). The absolute value of the difference in L ^{* on} each surface measured was defined as ΔL ^*, and the absolute value of the difference in C ^* obtained from a ^* and b ^* was determined as ΔC ^* . A diameter of 10 mm was adopted as the effective area for color tone evaluation.

Synthesis Example 1 (Synthesis of zirconia powder)
(Zirconia powder A1)
A hydrated zirconia sol was obtained by hydrolyzing an aqueous solution of zirconium oxychloride. Yttrium chloride was added to the hydrated zirconia sol so that the yttria concentration was 5.2 mol%, and then this was dried at 180 ° C. The dried zirconia sol was calcined at 1160 ° C. for 2 hours, washed with distilled water, and dried in the air at 110 ° C. This is mixed with α-alumina, terbium oxide and distilled water to form a slurry, which is treated with a ball mill for 22 hours to contain 0.05% by mass of alumina and 0.07% by mass of terbium oxide, and the balance is 5. A slurry containing a powder of zirconia containing .2 mol% yttria was obtained.

After the ball mill treatment, an acrylic acid-based binder (acrylic resin) was added to the slurry and mixed so that the weight ratio of the binder (binder) to the weight of the mixed powder in the slurry was 3.07% by mass. The mixed slurry was spray-dried at 180 ° C., and 3.07% by mass of an acrylic acid-based binder (acrylic resin), 0.05% by mass of alumina, and 0.07% by mass of terbium oxide (0 as a stabilizer). A powder granule containing 0.01 mol%) and having a balance of 5.2 mol% yttria-containing zirconia and an average aggregation diameter of 45 μm was obtained.

(Zirconia powder A2)
Except for the fact that ittoria was 4.75 mol% and terbium oxide was 0.175% by mass, and that an acrylic acid-based binder was added to the slurry and mixed so that the weight ratio of the binder was 3.04% by mass. Contains 3.04% by mass of an acrylic acid-based binder, 0.05% by mass of alumina and 0.175% by mass of terbium oxide (0.03 mol% as a stabilizer) in the same manner as the zirconia powder A1. Was composed of 4.75 mol% itria-containing zirconia, and powder granules having an average aggregation diameter of 45 μm were obtained.

(Zirconia powder A3 to A14)
A hydrated zirconia sol was obtained by hydrolyzing an aqueous solution of zirconium oxychloride. After adding yttrium chloride and / or erbium oxide to the hydrated zirconia sol, it was dried at 180 ° C. The dried zirconia sol was calcined at 1160 ° C. for 2 hours, washed with distilled water, and dried in the air at 110 ° C. Terbium oxide and / or cobalt oxide, α-alumina, and distilled water were mixed with this to prepare a slurry.

It has the composition shown in the table below in the same manner as zirconia powder A1 except that the obtained slurry is used, contains acrylic acid-based binder, alumina, cobalt oxide and terbium oxide, and the balance is yttria and / or elvia. Zirconia powders A3 to A14 composed of contained zirconia were obtained.

Synthesis example 2
(Zirconia powder B1)
The same method as for zirconia powder A1 except that yttria was set to 4.0 mol% and an acrylic acid-based binder was added to the slurry and mixed so that the weight ratio of the binder was 3.10% by mass. It contains 3.10% by mass of acrylic acid-based binder, 0.05% by mass of alumina, 0.07% by mass of terbium oxide (0.01 mol% as a stabilizer), and the balance consists of 4.0 mol% yttria-containing zirconia. , Powder granules having an average agglomeration diameter of 46 μm were obtained.
(Zirconia powder B2)
Except for the fact that ittoria was 4.0 mol% and terbium oxide was 0.175% by mass, and that an acrylic acid-based binder was added to the slurry and mixed so that the weight ratio of the binder was 3.07% by mass. In the same manner as zirconia powder A1, 3.07% by mass of acrylic acid binder, 0.05% by mass of alumina and 0.175% by mass of terbium oxide (0.03 mol% as stabilizer) are contained, and the balance is Powder granules composed of 4.0 mol% itria-containing zirconia and having an average aggregation diameter of 46 μm were obtained.
(Zirconia powder B3 to 11)
A hydrated zirconia sol was obtained by hydrolyzing an aqueous solution of zirconium oxychloride. After adding yttrium chloride and erbium oxide to the hydrated zirconia sol, it was dried at 180 ° C. The dried zirconia sol was calcined at 1160 ° C. for 2 hours, washed with distilled water, and dried in the air at 110 ° C. Terbium oxide, cobalt oxide, α-alumina, and distilled water were mixed with this to prepare a slurry.

It has the composition shown in the table below in the same manner as zirconia powder B1 except that the obtained slurry is used, contains acrylic acid-based binder, alumina, cobalt oxide and terbium oxide, and the balance is yttria and ervia-containing zirconia. Zirconia powders B3 to B14 consisting of these were obtained.

Synthesis example 3
A hydrated zirconia sol was obtained by hydrolyzing an aqueous solution of zirconium oxychloride. After adding yttrium chloride and erbium oxide to the hydrated zirconia sol, it was dried at 180 ° C. The dried zirconia sol was calcined at 1160 ° C. for 2 hours, washed with distilled water, and dried in the air at 110 ° C. Iron oxyhydroxide or iron oxyhydroxide and cobalt oxide, α-alumina, and distilled water were mixed with this to prepare a slurry.

It has the composition shown in the table below in the same manner as zirconia powder A1 except that the obtained slurry is used, and contains acrylic acid-based binder, alumina, iron oxyhydroxide, or iron oxyhydroxide and cobalt oxide. , C1 and C2 of zirconia powders having the balance of yttria and zirconia containing elvia were obtained.

Synthesis example 4
Acrylic acid-based binder, alumina, iron oxyhydroxide, or iron oxyhydroxide and cobalt oxide are used in the same manner as in Synthesis Example 3, except that the colorant, stabilizer, and binder are as shown in the table below. Zirconia powders D1 and D2 which were contained and the balance was composed of yttria and ervia-containing zirconia were obtained.

Example 1
(Molded body)
A mold having an inner diameter of 48 mm was filled with 25 g of zirconia powder A1, and then the mold was tapped to form a first powder layer. The same amount of zirconia powder B1 was filled on the first powder layer, the mold was tapped, and then uniaxial pressure press molding was performed at a pressure of 98 MPa. Then pressure 19
CIP treatment was performed at 6 MPa to obtain a laminated body composed of two layers, which was used as a molded product of this example. The stabilizer content of the first powder layer is 5.21 mol%, the stabilizer content of the second powder layer is 4.01 mol%, the difference in yttria content between layers is 1.2 mol%, and the binder. The difference in content was 0.02% by mass. In addition, the content of the molded product of this example and the colorants of the first powder layer and the second powder layer were 0.07% by mass.
(Temporary body)
The molded product was calcined at a heating rate of 20 ° C./hour, a calcining temperature of 1000 ° C., and a calcining time of 2 hours to obtain a laminate, which was used as the calcined product of this example.
(Sintered body)
The calcined body was fired at a heating rate of 100 ° C./hour, a sintering temperature of 1500 ° C., and a sintering time of 2 hours to obtain a laminated body, which was used as the sintered body of this example.

The stabilizer content of the sintered body was 4.6 mol%. The sintered body of the present embodiment △ L ^* and △ C ^* are, respectively, 2.33 and 2.64, it was confirmed that a laminate having a color change.

The warpage of each of the molded body, calcined body and sintered body was less than the measurement limit (less than 0.03 mm).

Example 2
A mold having an inner diameter of 48 mm was filled with 25 g of zirconia powder A2, and then the mold was tapped to form a first powder layer. The same amount of zirconia powder B2 was filled on the first powder layer, the mold was tapped, and then uniaxial pressure press molding was performed at a pressure of 49 MPa. Then, CIP treatment was performed at a pressure of 196 MPa to obtain a laminated body, which was used as a molded product of this example. The stabilizer content of the first powder layer is 4.78 mol%, the stabilizer content of the second powder layer is 4.03 mol%, the difference in yttria content between layers is 0.75 mol%, and the binder. The difference in content was 0.03% by mass. In addition, the content of the molded product of this example and the colorants of the first powder layer and the second powder layer were 0.175% by mass.

A calcined body and a sintered body were obtained in the same manner as in Example 1 except that the molded body was used.

The stabilizer content of the sintered body was 4.375 mol%. The sintered body of the present embodiment △ L ^* and △ C ^* are, respectively, 1.13 and 0.34, it was confirmed that a laminate having a color change.

From these examples, it can be seen that a laminate with a color change is obtained even though the content of the colorant in each layer is the same.

The warpage of each of the molded body, calcined body and sintered body was less than the measurement limit (less than 0.03 mm).

Example 3
The stabilizer content of the first powder layer was 5.40 mol% and the stabilizer content of the second powder layer was 5.40 mol% in the same manner as in Example 1 except that the zirconia powders A3 and B3 were used instead of the zirconia powders A1 and B1. The molded product of the present embodiment has a stabilizer content of 3.96 mol%, a difference in stabilizer content between layers of 1.44 mol%, and a difference in binder amount of 0.05% by mass. Obtained. The content of the molded product of this example and the colorants of the first powder layer and the second powder layer were 0.166% by mass.

A calcined body and a sintered body were obtained in the same manner as in Example 1 except that the molded body was used. The stabilizer content of the sintered body was 4.68 mol%.

The sintered body △ ^{L *} and △ ^{C *} are, respectively, 3.99 and 2.16, was a laminate color change is imparted. In addition, the warpage of each of the molded body, calcined body and sintered body was less than the measurement limit (less than 0.03 mm).

Example 4
The stabilizer content of the first powder layer was 5.25 mol% and the stabilizer content of the second powder layer was 5.25 mol% in the same manner as in Example 1 except that the zirconia powders A4 and B4 were used instead of the zirconia powders A1 and B1. The molded product of the present embodiment has a stabilizer content of 3.90 mol%, a difference in stabilizer content between layers of 1.35 mol%, and a difference in binder amount of 0.07 mass%. Obtained. The content of the molded product of this example and the colorants of the first powder layer and the second powder layer were all 0.393% by mass.

A calcined body and a sintered body were obtained in the same manner as in Example 1 except that the molded body was used. The stabilizer content of the sintered body was 4.58 mol%.

The sintered body △ ^{L *} and △ ^{C *} are, respectively, 3.32 and 1.91, was a laminate color change is imparted. In addition, the warpage of each of the molded body, calcined body and sintered body was less than the measurement limit (less than 0.03 mm).

Example 5
The stabilizer content of the first powder layer was 5.05 mol% and the stabilizer content of the second powder layer was 5.05 mol% in the same manner as in Example 1 except that the zirconia powders A5 and B5 were used instead of the zirconia powders A1 and B1. The molded product of the present embodiment has a stabilizer content of 3.78 mol%, a difference in stabilizer content between layers of 1.27 mol%, and a difference in binder amount of 0.05% by mass. Obtained. The content of the molded product of this example and the colorants of the first powder layer and the second powder layer were 0.727% by mass.

A calcined body and a sintered body were obtained in the same manner as in Example 1 except that the molded body was used. The stabilizer content of the sintered body was 4.42 mol%.

The sintered body △ ^{L *} and △ ^{C *} are, respectively, 2.96 and 1.86, was a laminate color change is imparted. In addition, the warpage of each of the molded body, calcined body and sintered body was less than the measurement limit (less than 0.03 mm).

Example 6
The stabilizer content of the first powder layer was 5.43 mol% and the stabilizer content of the second powder layer was 5.43 mol% in the same manner as in Example 1 except that the zirconia powders A6 and B6 were used instead of the zirconia powders A1 and B1. The molded product of the present embodiment has a stabilizer content of 3.96 mol%, a difference in stabilizer content between layers of 1.47 mol%, and a difference in binder amount of 0.06 mass%. Obtained. The content of the molded product of this example and the colorants of the first powder layer and the second powder layer were 0.067% by mass.

A calcined body and a sintered body were obtained in the same manner as in Example 1 except that the molded body was used. The stabilizer content of the sintered body was 4.69 mol%.

The sintered body △ ^{L *} and △ ^{C *} are, respectively, 4.20 and 2.80, was a laminate color change is imparted. In addition, the warpage of each of the molded body, calcined body and sintered body was less than the measurement limit (less than 0.03 mm).

Example 7
The stabilizer content of the first powder layer was 5.17 mol% and the stabilizer content of the second powder layer was 5.17 mol% in the same manner as in Example 1 except that the zirconia powders A7 and B7 were used instead of the zirconia powders A1 and B1. The molded product of the present embodiment has a stabilizer content of 3.91 mol%, a difference in stabilizer content between layers of 1.26 mol%, and a difference in binder amount of 0.06 mass%. Obtained. The content of the molded product of this example and the colorants of the first powder layer and the second powder layer were 0.413% by mass.

A calcined body and a sintered body were obtained in the same manner as in Example 1 except that the molded body was used. The stabilizer content of the sintered body was 4.54 mol%.

The sintered body △ ^{L *} and △ ^{C *} are, respectively, 3.10 and 2.09, was a laminate color change is imparted. In addition, the warpage of each of the molded body, calcined body and sintered body was less than the measurement limit (less than 0.03 mm).

Example 8
The stabilizer content of the first powder layer was 5.38 mol% and the stabilizer content of the second powder layer was 5.38 mol% in the same manner as in Example 1 except that the zirconia powders A8 and B8 were used instead of the zirconia powders A1 and B1. The molded product of the present embodiment has a stabilizer content of 3.87 mol%, a difference in stabilizer content between layers of 1.51 mol%, and a difference in binder amount of 0.06 mass%. Obtained. The content of the molded product of this example and the colorants of the first powder layer and the second powder layer were 0.08% by mass.

A calcined body and a sintered body were obtained in the same manner as in Example 1 except that the molded body was used. The stabilizer content of the sintered body was 4.63 mol%.

The sintered body △ ^{L *} and △ ^{C *} are, respectively, 3.67 and 2.37, was a laminate color change is imparted. In addition, the warpage of each of the molded body, calcined body and sintered body was less than the measurement limit (less than 0.03 mm).

Example 9
The stabilizer content of the first powder layer was 4.95 mol% and the stabilizer content of the second powder layer was 4.95 mol% in the same manner as in Example 1 except that the zirconia powders A9 and B9 were used instead of the zirconia powders A1 and B1. The molded product of the present embodiment has a stabilizer content of 3.59 mol%, a difference in stabilizer content between layers of 1.36 mol%, and a difference in binder amount of 0.06 mass%. Obtained. The content of the molded product of this example and the colorants of the first powder layer and the second powder layer were 0.665% by mass.

A calcined body and a sintered body were obtained in the same manner as in Example 1 except that the molded body was used. The stabilizer content of the sintered body was 4.27 mol%.

The sintered body △ ^{L *} and △ ^{C *} are, respectively, 2.20 and 2.64, was a laminate color change is imparted. In addition, the warpage of each of the molded body, calcined body and sintered body was less than the measurement limit (less than 0.03 mm).

Example 10
In the same manner as in Example 1 except that the zirconia powders A10 and B10 were used instead of the zirconia powders A1 and B1, the stabilizer content of the first powder layer was 5.21 mol% and that of the second powder layer. The molded product of the present embodiment has a stabilizer content of 3.85 mol%, a difference in stabilizer content between layers of 1.36 mol%, and a difference in binder amount of 0.09 mass%. Obtained. The content of the molded product of this example and the colorants of the first powder layer and the second powder layer were 0.405% by mass.

A calcined body and a sintered body were obtained in the same manner as in Example 1 except that the molded body was used. The stabilizer content of the sintered body was 4.53 mol%.

The sintered body △ ^{L *} and △ ^{C *} are, respectively, 3.70 and 1.83, was a laminate color change is imparted. In addition, the warpage of each of the molded body, calcined body and sintered body was less than the measurement limit (less than 0.03 mm).

Example 11
The stabilizer content of the first powder layer was 5.22 mol% and the stabilizer content of the second powder layer was 5.22 mol% in the same manner as in Example 1 except that the zirconia powders A11 and B11 were used instead of the zirconia powders A1 and B1. The molded product of the present embodiment has a stabilizer content of 3.82 mol%, a difference in stabilizer content between layers of 1.39 mol%, and a difference in binder amount of 0.07 mass%. Obtained. The content of the molded product of this example and the colorants of the first powder layer and the second powder layer were both 0.217% by mass.

A calcined body and a sintered body were obtained in the same manner as in Example 1 except that the molded body was used. The stabilizer content of the sintered body was 4.52 mol%.

The sintered body △ ^{L *} and △ ^{C *} are, respectively, 3.30 and 2.28, was a laminate color change is imparted. In addition, the warpage of each of the molded body, calcined body and sintered body was less than the measurement limit (less than 0.03 mm).

Example 12
Examples except that a mold having an inner diameter of 110 mm was used, uniaxial pressure press molding was performed at a pressure of 19.8 MPa, and zirconia powders A3 and B3 were used instead of zirconia powders A1 and B1. In the same manner as in 1, the stabilizer content of the first powder layer is 5.40 mol% and the stabilizer content of the second powder layer is 3.96 mol%, and the difference in the stabilizer content between the layers. Was 1.44 mol%, and the difference in the amount of the binder was 0.05% by mass, and the molded product of the present embodiment was obtained. The content of the molded product of this example and the colorants of the first powder layer and the second powder layer were 0.166% by mass.

A calcined body and a sintered body were obtained in the same manner as in Example 1 except that the molded body was used. The stabilizer content of the sintered body was 4.68 mol%.

The sintered body △ ^{L *} and △ ^{C *} are, respectively, 3.99 and 2.16, was a laminate color change is imparted. The molded body, calcined body and sintered body had warpages of 0.05 mm, 0.09 mm and 0.05 mm, respectively, and deformation amounts of 0.05, 0.09 and 0.06, respectively.

Example 13
The stabilizer content of the first powder layer was 5.43 mol% and the second was the same method as in Example 1 except that a mold having an inner diameter of 110 mm was used and zirconia powders A6 and B6 were used. The stabilizer content of the powder layer is 3.96 mol%, the difference in the stabilizer content between the layers is 1.47 mol%, and the difference in the amount of the binder is 0.06 mass%. A molded product was obtained. The content of the molded product of this example and the colorants of the first powder layer and the second powder layer were 0.067% by mass.

A calcined body and a sintered body were obtained in the same manner as in Example 1 except that the molded body was used. The stabilizer content of the sintered body was 4.69 mol%.

The sintered body △ ^{L *} and △ ^{C *} are, respectively, 4.20 and 2.80, was a laminate color change is imparted. In addition, the warp of both the molded body and the sintered body was less than the measurement limit (less than 0.03 mm), but the calcined body had a warp of 0.06 mm and a deformation amount of 0.06.

Example 14
The stabilizer content of the first powder layer was 5.17 mol% and the second was the same method as in Example 1 except that a mold having an inner diameter of 110 mm was used and zirconia powders A13 and B7 were used. The stabilizer content of the powder layer is 3.91 mol%, the difference in the stabilizer content between the layers is 1.26 mol%, and the difference in the amount of the binder is 0.06 mass%. A molded product was obtained. The content of the molded product of this example and the colorants of the first powder layer and the second powder layer were 0.413% by mass.

A calcined body and a sintered body were obtained in the same manner as in Example 1 except that the molded body was used. The stabilizer content of the sintered body was 4.54 mol%.

The sintered body △ ^{L *} and △ ^{C *} are, respectively, 3.27 and 2.25, was a laminate color change is imparted. The warpage of both the molded body and the sintered body was less than the measurement limit (less than 0.03 mm), but the calcined body had a warp of 0.19 mm and a deformation amount of 0.18.

Example 15
The stabilizer content of the first powder layer was 5.22 mol% and the second was the same method as in Example 1 except that a mold having an inner diameter of 110 mm was used and zirconia powders A14 and B11 were used. In the present embodiment, the stabilizer content of the powder layer is 3.82 mol%, the difference in the stabilizer content between the layers is 1.40 mol%, and the difference in the amount of the binder is 0.05% by mass. A molded product was obtained. The content of the molded product of this example and the colorants of the first powder layer and the second powder layer were both 0.217% by mass.

A calcined body and a sintered body were obtained in the same manner as in Example 1 except that the molded body was used. The stabilizer content of the sintered body was 4.52 mol%.

The sintered body △ ^{L *} and △ ^{C *} are, respectively, 3.14 and 2.22, was a laminate color change is imparted. The warpage of the molded body was less than the measurement limit (less than 0.03 mm), but the calcined body and the sintered body had warpages of 0.19 mm and 0.03 mm and deformation amounts of 0.18 and 0, respectively. It was .04.

From these examples, it was confirmed that the smaller the difference in alumina content between the layers, the more the warpage of the calcined body tends to be suppressed.

Example 16
Example 1 and Example 1 except that a mold having an inner diameter of 110 mm was used, uniaxial pressure press molding was performed at a pressure of 98 MPa, and zirconia powders C1 and D1 were used instead of zirconia powders A1 and B1. In the same manner, the stabilizer content of the first powder layer is 5.19 mol%, the stabilizer content of the second powder layer is 3.93 mol%, and the difference in the stabilizer content between the layers is 1. A molded product of the present embodiment having an amount of .26 mol% and a difference in the amount of binder of 0.05% by mass was obtained. The content of the molded product of this example and the colorants of the first powder layer and the second powder layer were 0.150% by mass.

A calcined body and a sintered body were obtained in the same manner as in Example 1 except that the molded body was used. The stabilizer content of the sintered body was 4.56 mol%.

The sintered body △ ^{L *} and △ ^{C *} are, respectively, 4.27 and 2.92, was a laminate color change is imparted. In addition, the warp of both the molded body and the sintered body was less than the measurement limit (less than 0.03 mm), but the calcined body had a warp of 0.12 mm and a deformation amount of 0.11.

Example 17
Example 1 and Example 1 except that a mold having an inner diameter of 110 mm was used, uniaxial pressure press molding was performed at a pressure of 98 MPa, and zirconia powders C2 and D2 were used instead of zirconia powders A1 and B1. In the same manner, the stabilizer content of the first powder layer is 5.09 mol%, the stabilizer content of the second powder layer is 3.99 mol%, and the difference in the stabilizer content between the layers is 1. A molded product of the present embodiment having an amount of .10 mol% and a difference in the amount of binder of 0.05% by mass was obtained. The content of the molded product of this example and the colorants of the first powder layer and the second powder layer were both 0.232% by mass.

A calcined body and a sintered body were obtained in the same manner as in Example 1 except that the molded body was used. The stabilizer content of the sintered body was 4.54 mol%.

The sintered body △ ^{L *} and △ ^{C *} are, respectively, 4.93 and 2.71, was a laminate color change is imparted. In addition, the warp of both the molded body and the sintered body was less than the measurement limit (less than 0.03 mm), but the calcined body had a warp of 0.16 mm and a deformation amount of 0.15.

Comparative Example 1
A mold having an inner diameter of 110 mm is filled with zirconia powder containing 0.094% by mass of 25 g of iron oxide and 0.0045% by mass of cobalt oxide, and the balance is 4 mol% yttria-containing zirconia, and then tapping the mold. 1 powder layer was used. The same amount of zirconia powder composed of 4 mol% yttria-containing zirconia was filled on the first powder layer, and the mold was tapped to form a second powder layer, and then uniaxial pressure press molding was performed at a pressure of 98 MPa. Then, CIP treatment was performed at a pressure of 196 MPa to obtain a laminated body composed of two layers, which was used as a molded product of this comparative example. The difference in yttria content between the layers was 0 mol%, and the difference in the amount of binder was 0.02% by mass.

When a calcined product was produced by the same method as in Example 1 except that the molded product was used, the warp was 0.67 mm.

In the yttria content of the first layer and the second layer, but the content of the colorant was different by 0.139% by mass, the calcined body of this comparative example had a large warp.

Reference example 1
A mold having an inner diameter of 48 mm was filled with zirconia powder A1, the mold was tapped, and then uniaxial pressure press molding was performed at a pressure of 49 MPa. Then, CIP treatment was performed at a pressure of 196 MPa to obtain a molded product.

A calcined body and a sintered body were obtained in the same manner as in Example 1 except that the molded body was used.

The obtained sintered body contains 0.05% by mass of alumina, and the balance is composed of 5.2 mol% yttria and 0.01 mol% terbium oxide-containing zirconia, and the crystal phase thereof is a tetragonal main phase. It consisted of tetragonal and cubic crystals. The total light transmittance of the sintered body was 42%.

Reference example 2
A mold having an inner diameter of 48 mm was filled with zirconia powder A2, the mold was tapped, and then uniaxial pressure press molding was performed at a pressure of 49 MPa. Then, CIP treatment was performed at a pressure of 196 MPa to obtain a molded product.

A calcined body and a sintered body were obtained in the same manner as in Example 1 except that the molded body was used.

The obtained sintered body contains 0.05% by mass of alumina, and the balance is composed of 4.75 mol% yttria and 0.03 mol% terbium oxide-containing zirconia, and the crystal phase thereof is a tetragonal prime as the main phase. Consists of tetragonal and cubic crystals. The total light transmittance of the sintered body was 40%.

Reference example 3
A mold having an inner diameter of 48 mm was filled with zirconia powder B1, the mold was tapped, and then uniaxial pressure press molding was performed at a pressure of 49 MPa. Then, CIP treatment was performed at a pressure of 196 MPa to obtain a molded product.

A calcined body and a sintered body were obtained in the same manner as in Example 1 except that the molded body was used.

The obtained sintered body contains 0.05% by mass of alumina, and the balance is composed of 4.0 mol% yttria and 0.01 mol% terbium oxide-containing zirconia, and the crystal phase thereof is a tetragonal main phase. It consisted of tetragonal and cubic crystals. The color tone of the sintered body was 78.51 for L ^* , 0.18 for a ^* and 25.06 for b ^* , and the total light transmittance was 40%.

Reference example 4
A mold having an inner diameter of 48 mm was filled with zirconia powder B2, the mold was tapped, and then uniaxial pressure press molding was performed at a pressure of 49 MPa. Then, CIP treatment was performed at a pressure of 196 MPa to obtain a molded product.

A calcined body and a sintered body were obtained in the same manner as in Example 1 except that the molded body was used.

The obtained sintered body contains 0.05% by mass of alumina, and the balance is composed of 4.0 mol% yttria and 0.03 mol% terbium oxide-containing zirconia, and the crystal phase thereof is a cubic crystal as the main phase. It consisted of tetragonal and cubic crystals. The color tone of the sintered body was 77.88 for L ^* , 6.02 for a ^* and 31.70 for b ^* , and the total light transmittance was 38%.

11: Zirconia having a necking structure 200, 300, 400: Zirconia calcined body 21, 31: First composition layer 22, 32: Second composition layer 33: Third composition layer 42A, 42B: Feeler gauge 43: Temporary Burnt size 500: Zirconia sintered body 51: Load 52: Distance between fulcrums

Claims (14)

A colorant containing a stabilizer and having a necking structure, and a zirconia composition layer containing two or more layers of a zirconia composition layer, and the colorant contained in each zirconia composition layer and the colorant thereof. The contents are equal to each other, at least
A first zirconia composition layer containing a zirconia having a stabilizer content of 3.3 mol% or more and a colorant, and the like.
A second zirconia composition layer containing a zirconia contained in the first zirconia composition layer and a zirconia having a different content of a stabilizer and a colorant, and a second zirconia composition layer.
A calcined body characterized by being provided with. The calcined product according to claim 1, wherein the content of the zirconia stabilizer containing the stabilizer contained in the second zirconia composition layer is 1.5 mol% or more and 7.0 mol% or less. The calcined product according to claim 1 or 2, wherein the content of the zirconia stabilizer containing the stabilizer contained in the second zirconia composition layer is 4.5 mol% or more and 7.0 mol% or less. The item according to any one of claims to 3, wherein the content of the zirconia stabilizer containing the stabilizer contained in the first zirconia composition layer is 3.3 mol% or more and 5.5 mol% or less. Temporary fired body. According to any one of claims 1 to 4, the difference between the stabilizer content of the first zirconia composition layer and the stabilizer content of the second zirconia composition layer is 0.2 mol% or more. The described calcined body. Stabilizers include yttrium (Y ₂ O ₃ ), calcia (CaO), magnesia (MgO) and ceria (CeO ₂ ), placeodymium oxide (Pr ₆ O ₁₁ ), neodymium oxide (Nd ₂ O ₃ ), and terbium oxide (Nd ₂ O ₃ ). The calcined product according to any one of claims 1 to 5, which is one or more selected from the group of Tb ₄ O ₇ ), erbium oxide (Er ₂ O ₃ ) and ytterbium oxide (Yb ₂ O ₃ ). The calcined product according to any one of claims 1 to 6, wherein the colorant is at least one of a transition metal element and a lanthanoid-based rare earth element. The calcined product according to any one of claims 1 to 7, wherein the content of the colorant is 0.01% by mass or more and 1.0% by mass or less. The calcined product according to any one of claims 1 to 8, wherein at least one layer of the zirconia composition layer contains alumina. The calcined body according to any one of claims 1 to 9, wherein the warp measured using a JIS B 7524: 2008 conformity gauge is 1.0 mm or less. A colorant having a structure in which two or more powder composition layers composed of a powder composition containing zirconia containing a stabilizer, a colorant, and a binder are laminated, and the colorant contained in each powder composition layer. And their contents are equal to each other, at least
A first powder composition layer containing zirconia having a stabilizer content of 3.3 mol% or more, a colorant, and a binder.
A second powder composition layer containing zirconia and a stabilizer contained in the first powder composition layer having different contents, a colorant, and a binder.
With
A step of calcining a molded product in which the difference in the content of the binder between the first powder composition layer and the second powder composition layer exceeds 0.01% by mass at 800 ° C. or higher and lower than 1200 ° C. The method for producing a calcined product according to any one of claims 1 to 10, wherein the calcined product has. The production method according to claim 11, wherein the binder is at least one selected from the group of polyvinyl alcohol, polyvinyl butyrate, wax and acrylic resin. The production method according to claim 11 or 12, wherein the powder composition contained in the powder composition layer is a powder in a granulated state. A dental material containing a calcined body according to any one of claims 1 to 10.