JP2020142983A - Zirconia sintered body - Google Patents

Abstract

To provide at least one of a laminate having a change in texture derived from zirconia, especially a change in translucent feeling, and suitable for a dental prosthetic member, its precursor, and a manufacturing method thereof.SOLUTION: A sintered body 100 comprises: a first zirconia layer 11 having a structure in which two or more zirconia layers containing zirconia containing a stabilizer are laminated, and containing at least zirconia having a content of the stabilizer of 4 mol% or more; and a second zirconia layer 12 containing zirconia having a content of the stabilizer, different from that of zirconia contained in the first zirconia layer.SELECTED DRAWING: Figure 1

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.

Zirconia accounts for the majority of the raw material powder. Nevertheless, even if the raw material powders have different content of additives of less than 0.1% by mass, the heat shrinkage behavior of the two powders is significantly different. When a molded product obtained by laminating raw material powders having such a slight difference in composition is heat-treated, problems such as peeling of a part of the layer or generation of strain occur. The above-mentioned defects occur even when the same zirconia is added with an additive. In order to heat-treat the molded product without causing these defects, special adjustments and treatments have been required (for example, Patent Documents 1 and 2).

According to Patent Document 1, the composition and heat shrinkage behavior of the raw material powder are adjusted by coating with a dopant, and by molding the raw material powder, a sintered body made of laminated bodies having different color tones without distortion can be obtained. It is disclosed. 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 have a composition difference of less than 0.5% by mass even if the difference in the content of additives between layers is large. Furthermore, since zirconia, which occupies most of the raw material powder, has the same composition, these laminates also have the same texture mainly derived from the translucency of zirconia. Therefore, the texture is different from that of the natural tooth having the texture derived from the change in the translucency.

The present disclosure provides at least one of a laminate, a precursor thereof, or a method for producing the same, which has a change in texture derived from zirconia, particularly a change in translucency, and is suitable as a dental prosthetic member. The purpose is to do.

The present inventors focused on the molded product before the heat treatment, that is, the state after molding of the raw material powder. As a result, the molded product in which the raw material powders having different zirconia stabilizer contents are laminated has the same strain state generated at the time of molding as the molded product in which the raw material powders having different additive contents are laminated. Confirmed that they were significantly different. It was also confirmed that such strain has a great influence on the state of the calcined body and the sintered body after the heat treatment. Furthermore, it has been found that by controlling the state of the molded product, even if the laminate in which the raw material powders having different contents of the zirconia stabilizer are laminated is heat-treated, the above-mentioned problems are less likely to occur.

That is, the gist of the present disclosure is as follows.
[1] It has a structure in which two or more zirconia layers containing zirconia containing a stabilizer are laminated, and at least
A first zirconia layer containing zirconia having a stabilizer content of 4 mol% or more,
A second zirconia layer containing zirconia contained in the first zirconia layer and a zirconia having a different content of the stabilizer,
A sintered body characterized by comprising.
[2] The sintered body according to the above [1], wherein the content of the stabilizer-containing zirconia stabilizer contained in the second zirconia layer is 1.5 mol% or more and 7.0 mol% or less.
[3] The sintering according to the above [1] or [2], wherein the content of the stabilizer-containing zirconia stabilizer contained in the second zirconia layer is 5.0 mol% or more and 7.0 mol% or less. body.
[4] The content of the stabilizer-containing zirconia stabilizer contained in the first zirconia layer is 4.0 mol% or more and 6.0 mol% or less, according to any one of the above [1] to [3]. The sintered body described.
[5] Any one of the above [1] to [4], wherein the difference between the stabilizer content of the first zirconia layer and the stabilizer content of the second zirconia layer is 0.2 mol% or more. The sintered body described in.
[6] The stabilizer is any one or more of the above [1] to [5] selected from the group of yttria (Y ₂ O ₃ ), calcia (CaO), magnesia (MgO) and ceria (CeO ₂ ). The sintered body described in one.
[7] The sintered body according to any one of the above [1] to [6], wherein at least one of the zirconia layers contains alumina.
[8] The sintered body according to any one of the above [1] to [7], wherein the warp measured by using a feeler gauge conforming to JIS B 7524: 2008 is 1.0 mm or less.
[9] The sintered body according to any one of the above [1] to [8], wherein the density 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. ..
[10] The sintered body according to any one of the above [1] to [9], which has a zirconia layer having a total light transmittance of 30% or more and 50% or less with respect to light having a wavelength of 600 nm at a sample thickness of 1.0 mm.
[11] The sintered body according to any one of the above [1] to [10], wherein the three-point bending strength measured by a method according to JIS R 1601 is 500 MPa or more.
[12] It has a structure in which two or more powder composition layers composed of a powder composition containing zirconia containing a stabilizer and a binder are laminated, and at least
A first powder composition layer containing zirconia having a stabilizer content of 4 mol% or more and a binder, and the like.
A second powder composition layer containing zirconia contained in the first powder composition layer and a zirconia having a different content of a stabilizer, and a binder.
With
A step of sintering 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 1200 ° C. or higher and 1600 ° C. or lower. The method for producing a sintered body according to any one of the above [1] to [11], which comprises.
[13] It has a structure in which two or more powder composition layers composed of a powder composition containing zirconia containing a stabilizer and a binder are laminated, and at least
A first powder composition layer containing zirconia having a stabilizer content of 4 mol% or more and a binder, and the like.
A second powder composition layer containing zirconia contained in the first powder composition layer and a zirconia having a different content of a stabilizer, 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 is calcined at 800 ° C. or higher and lower than 1200 ° C. The process of making a calcined body and
The method for producing a sintered body according to any one of the above [1] to [11], which comprises a step of sintering a calcined body at 1200 ° C. or higher and 1600 ° C. or lower.
[14] The production method according to the above [12] or [13], wherein the warpage of the molded product measured using a feeler gauge conforming to JIS B 7524: 2008 is 1.0 mm or less.
[15] The production method according to any one of the above [12] to [14], wherein the binder is at least one selected from the group of polyvinyl alcohol, polyvinyl butyrate, wax and acrylic resin.
[16] The production method according to any one of the above [12] to [15], wherein the powder composition contained in the powder composition layer is a powder in a granulated state.
[17] The production method according to any one of the above [12] to [16], wherein the density of the molded product is 2.4 g / cm ³ or more and 3.7 g / cm ³ or less.
[18] A dental material containing the sintered body according to any one of the above [1] to [11].

The present disclosure provides a laminate, a precursor thereof, or a method for producing the same, which has a change in texture derived from zirconia, particularly a change in translucency, and is suitable as a dental prosthetic member. be able to.

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

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

The present embodiment has a structure in which two or more zirconia layers containing zirconia containing a stabilizer are laminated, and at least,
A first zirconia layer containing zirconia having a stabilizer content of 4 mol% or more,
A second zirconia layer containing zirconia contained in the first zirconia layer and a zirconia having a different content of the stabilizer,
It is a sintered body, characterized in that it is provided with.

The sintered body of the present embodiment is a composition having a multi-layer 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 of the present embodiment has a zirconia layer containing zirconia containing a stabilizer (hereinafter, also simply referred to as “zirconia layer”). The zirconia layer consists of zirconia crystal particles containing a stabilizer. Therefore, the sintered body of the present embodiment can be regarded as a laminate having two or more layers containing zirconia composed of zirconia crystal particles containing a stabilizer.

FIG. 1 is a schematic view showing an example of the structure of the sintered body of the present embodiment, and shows a cross section of the sintered body (100) having a structure in which two zirconia layers containing zirconia containing a stabilizer are laminated. It is shown schematically. In FIG. 1, 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 sintered body (100) includes a first zirconia layer containing zirconia having a stabilizer content of 4 mol% or more (hereinafter, also referred to as “first layer”) (11) among the zirconia layers. It is provided with a second zirconia layer (hereinafter, also referred to as "second layer") (12) containing zirconia contained in the first zirconia layer and zirconia having a different content of a stabilizer, and the first zirconia layer. The layer (11) and the second layer (12) are shown as a sintered body having a structure in which they are laminated adjacent to each other. By having a structure in which zirconia layers containing zirconia having different contents of stabilizers are laminated, the sintered body becomes a laminated body in which changes in texture, particularly changes in translucency, can be visually recognized. In the sintered body (100), the first layer and the second layer are in contact with each other via an interface. However, the sintered 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 sintered body (100), the thicknesses of the first layer and the second layer are shown to be about the same. However, in the sintered body of the present embodiment, the thickness of each layer (hereinafter, also referred to as “layer thickness”) may be different, and the layer thickness of either the first layer or the second layer is thick. You may. For example, the layer thicknesses of the first layer and the second layer satisfy the following relationship, and the layer thickness of the zirconia layer having a large stabilizer content is higher than the layer thickness of the zirconia layer having a low stabilizer content. It can be illustrated that it is thick. 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 sintered 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 prosthetic 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 size of the sintered body of the present embodiment is 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 sintered body of the present embodiment in the stacking direction, that is, the height of the sintered 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 sintered body of the present embodiment, it is preferable that the first layer and the second layer are laminated adjacent to each other. Further, the first layer and the second layer are the lowest layer in the stacking direction (hereinafter, also referred to as "bottom layer") or the top layer in the stacking direction (hereinafter, also referred to as "top layer"), respectively. It is preferably located in. It is preferable that one layer of the first layer or the second layer is located at the lowest layer, and the other layer of the first layer or the second layer is located at the uppermost layer.

The sintered body of the present embodiment may have a structure in which two or more zirconia layers containing zirconia containing a stabilizer are laminated, and the structure in which three or more zirconia layers and further four or more layers are laminated. May have. As the number of layers increases, the sintered body becomes a laminated body in which fine changes in texture can be visually recognized. When the texture is more similar to that of natural teeth, the sintered body of the present embodiment has two or more and 10 or less zirconia layers, two or more and five or less layers, and two or more and four or less layers. It can be exemplified that the structure is as follows.

The zirconia layer other than the first layer and the second layer (hereinafter, also referred to as “third layer”) is the minimum value or the maximum value of the content of the zirconia stabilizer contained in the first layer and the second layer. Any zirconia layer containing zirconia containing the following stabilizer may be used. The sintered body of the present embodiment may include a plurality of third layers.

The stacking order of the third layer is arbitrary, but a structure in which the third layer is sandwiched between the first layer and the second layer is preferable. When a plurality of third layers (the third layer of the first layer is also referred to as "third layer", the third layer of the second layer or higher is also referred to as "fourth layer", "fifth layer", etc.), this The sintered body of the embodiment preferably has a structure in which zirconia layers are laminated so that the change in the content of the stabilizer in the stacking direction becomes constant, that is, increases (or decreases). In the present embodiment, the structure in which the third layer is sandwiched between the first layer and the second layer is a structure in which the third layer is located between the first layer and the second layer in the stacking direction. The structure is not limited to a structure in which the third layer is laminated directly adjacent to both the first layer and the second 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. 2 is a schematic view showing another example of the structure of the sintered body of the present embodiment, and is a schematic view showing a cross section of the sintered body (200) having a structure in which three zirconia layers are laminated. The sintered body (200) has a structure in which a third layer (23) is laminated in addition to the first layer (21) and the second layer (22), and the first layer (21) and the second layer ( It has a structure in which a third layer (23) is sandwiched between it and 22).

When a plurality of zirconia layers such as the fourth layer and the fifth layer are contained, it is preferable that the zirconia layers are laminated so that the content of the stabilizer changes constantly in the stacking direction. As a result, a translucent gradation can be formed in the stacking direction.

The sintered body of the present embodiment preferably has a warp (hereinafter, also simply referred to as “warp”) of 1.0 mm or less as measured using a feeler gauge conforming to JIS B 7524: 2008. A sintered body having a structure having two or more zirconia layers becomes a shape warped in the stacking direction (or a direction opposite to the stacking direction) due to sintering. When such a sintered body is arranged on the horizontal plate, a gap is formed between the sintered 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 sintered 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 sintered body preferably has no warp (warp is 0 mm), but the sintered 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 sintered 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 sintered body is arranged so as to be in contact with the horizontal plate. FIG. 3 is a schematic view showing a method for measuring warpage. The sintered body (300) shows a cross section of a disk-shaped sample, and shows a sintered body in a state of being warped in the stacking direction (Y-axis direction). In FIG. 3, for the sake of explanation, the warp of the sintered body (300) is emphasized. As shown in FIG. 3, when measuring the warp, the convex portion of the concave-convex-shaped sintered body (300) is arranged so as to be in contact with the horizontal plate (31). As a result, a gap is formed between the surface (hereinafter, also referred to as “bottom surface”) in which the sintered body (300) and the horizontal plate (31) are in contact with each other and the horizontal plate (31). 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. 3, the gauge (32A) is located at the lower part of the bottom surface of the sintered body (300) and can be inserted into the gap, while the gauge (32B) is the sintered body (300). It is not located at the bottom of the bottom, indicating that it cannot be inserted into the gap. The gauges (32A) and (32B) in FIG. 3 are gauges having a thickness one step (for example, 0.01 mm) different from each other, and the warp of the sintered body (300) is the thickness of the gauge (32A). For the sake of simplicity of explanation, in FIG. 3, both gauges (32A) and (32B) 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 (32A), remove it, and then measure using a thicker gauge (32B), etc.).

The sintered body of the present embodiment preferably has a warp (hereinafter, also referred to as “deformation amount”) with respect to the dimensions of the sintered body of 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) / (sintered body size: mm) x 100

The size of the sintered body is the size of the sintered body in the direction perpendicular to the warp direction. Since the sintered body (300) in FIG. 3 is warped in the stacking direction (Y-axis direction), the dimensions of the sintered body (300) are horizontal (X-axis direction) perpendicular to the stacking direction. The size of (33). 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 sintered body of the present embodiment comprises a zirconia layer containing zirconia containing a stabilizer. The zirconia 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 sintered body and the zirconia layer of the present embodiment may contain not only stabilizer-containing zirconia but also unavoidable impurities such as hafonia (HfO ₂ ), but it is preferable that the sintered body and the zirconia layer do not contain impurities. Examples of impurities include silica (SiO ₂ ) and titania (TiO ₂ ), and it can be exemplified that the sintered body of the present embodiment substantially does not contain silica or titania.

In the sintered body of the present embodiment, the zirconia is preferably zirconia in which the zirconia sol heat-treated is sintered, and the zirconia obtained by hydrolyzing the zirconium compound is heat-treated. It is more preferable that the zirconia is in a sintered 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 stabilizer may have a function of suppressing the phase transition of zirconia. The stabilizer is preferably one or more selected from the group of yttria (Y ₂ O ₃ ), calcia (CaO), magnesia (MgO) and ceria (CeO ₂ ), and more preferably yttria. The stabilizer is in a state of being contained in zirconia and in a state of being dissolved in zirconia. Further, it is preferable that the sintered body of the present embodiment does not contain an undissolved stabilizer, that is, does not contain a stabilizer that is not solid-solved 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 is 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 layer (hereinafter, also referred to as “stabilizer content of the first layer”) is 4 mol% or more, and 4.1 mol% or more. It is preferably 4.2 mol% or more, and more preferably 4.2 mol% or more. The stabilizer content of the first layer is 6.0 mol% or less, further 5.8 mol% or less, further 5.5 mol% or less, and further 5.0 mol% or less. .. Examples of the stabilizer content of the first layer are 4 mol% or more and 6.0 mol% or less, and further 4 mol% or more and less than 5.0 mol%.

The content of the stabilizer-containing zirconia stabilizer contained in the second layer (hereinafter, also referred to as “stabilizer content of the second layer”) is different from the stabilizer content of the first layer. However, it is preferable that the stabilizer content of the second layer is larger than the stabilizer content of the first layer. That is, it is preferable that the sintered body of the present embodiment does not contain a zirconia layer in which the content of the zirconia stabilizer is less than 4 mol%. This makes it easier to obtain a sintered body that exhibits a translucent feeling closer to that of natural teeth.

The stabilizer content of the second layer may be 1.5 mol% or more, further 2.0 mol% or more, and further 3.0 mol% or more, but preferably 4.0 mol% or more. It is more preferably more than 4.0 mol%, further preferably 4.5 mol% or more, further preferably 5.0 mol% or more, and even more preferably more than 5.0 mol%. Further, the stabilizer content of the second 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. .. When the stabilizer contents of the first layer and the second layer are different and the stabilizer contents of both layers are in this range, the sintered body can be visually recognized as having a texture close to that of natural teeth. It becomes easier to show the texture. The stabilizer content of the second 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, further 5.0 mol% or more and 6.5 mol% or less, and more. Further, it may exceed 5.0 mol% and 6.5 mol% or less.

The sintered body of the present embodiment preferably includes at least a first zirconia layer and a zirconia layer containing zirconia having a stabilizer content of 5 mol% or more, and the first zirconia layer and It is more preferable to include a zirconia layer containing zirconia having a stabilizer content of more than 5 mol%. As another embodiment, the sintered body of the present embodiment has a stabilizer content of the first layer of 4.0 mol% or more and 5.1 mol% or less, and a stabilizer content of the second layer of 4. More preferably, it is 5 mol% or more and 6.0 mol% or less, the stabilizer content of the first layer is 4.0 mol% or more and 5.0 mol% or less, and the stabilizer content of the second layer is 5. It is more preferably more than 0 mol% and 6.0 mol% or less.

The stabilizer content of the stabilizer-containing zirconia contained in the third layer (hereinafter, also referred to as “stabilizer content of the third layer”) is the content of the zirconia contained in the first layer and the second layer. It is preferable that the content of the stabilizer is not less than the minimum value and not more than the maximum value, and more than the minimum value of the content of the zirconia stabilizer contained in the first layer and the second layer and less than the maximum value. The stabilizer content of the third 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. When the content of the zirconia stabilizer contained in the first layer is 4.0 mol% and the content of the zirconia stabilizer contained in the second layer is 6.0 mol%, the content of the zirconia stabilizer in the third layer is 6.0 mol%. The content of the stabilizer in the above is 4.0 mol% or more and 6.0 mol% or less, preferably more than 4.0 mol% and less than 6.0 mol%. When the stabilizer content of the third layer is the same as the stabilizer content of the first layer or the second layer, zirconia having the same stabilizer content as the stabilizer content of the third layer The zirconia layer located at the uppermost layer or the lowermost layer may be regarded as the first layer or the second layer.

The difference between the stabilizer content of the first layer and the stabilizer content of the second layer is preferably 0.2 mol% or more, more preferably 0.5 mol% or more, and 0.7 mol% or more. Is even more preferably 1.0 mol% or more, and even more preferably 1.2 mol% or more. The larger the difference in the stabilizer content, the larger the difference in translucency between the zirconia layers tends to be, but the larger the warp may be. If the difference between the stabilizer content of the first layer and the stabilizer content of the second layer is less than 2.5 mol% and further 2.0 mol% or less, the translucency of the sintered body is that of a natural tooth. It tends to have the same translucency. It is more preferable that the difference between the stabilizer content of the first layer and the stabilizer content of the second layer is 0.7 mol% or more and less than 2.5 mol%, and the warp is 0.5 mm or less.

In the sintered body of the present embodiment, the difference in the content of the stabilizer between the zirconia layers laminated adjacent to each other is 0.5 mol% or more and 3.0 mol% or less, and further 1.0 mol% or more and 2.5 mol% or more. Hereinafter, it is preferable to include a structure having a structure of 1.2 mol% or more and 2.0 mol% or less.

The content of the stabilizer of the sintered body of the present embodiment (content of the stabilizer as a whole of the sintered body) is arbitrary, but is, for example, more than 1.5 mol% and less than 7.0 mol%, and further. 2.5 mol% or more and 6.5 mol% or less, further 3.0 mol% or more and 6.0 mol% or less, further 3.5 mol% or more and 5.8 mol% or less, and further 4.1 mol% or more and 5.5 mol. % Or less, more preferably 4.7 mol% or more and 5.3 mol% or less. The stabilizer content of the sintered body is obtained from the following formula and varies depending on the thickness of each zirconia layer.
Stabilizer content of sintered body
= (Layer thickness of 1st layer / Height of sintered body) × Stabilizer content of 1st layer
+ (Layer thickness of second layer / height of sintered body) × Stabilizer content of second layer
＋ ・ ・ ・
+ (Layer thickness of nth layer / height of sintered body) × Stabilizer content of nth layer

Since the stabilizer content of the first layer is 4 mol% or more, for example, when the stabilizer content of the second layer is more than 4.0 mol%, two zirconia layers having the same layer thickness are provided. In the sintered body, the stabilizer content of the sintered body is more than 4.0 mol%.

In the sintered body of the present embodiment, the stabilizer content of the first layer is 4.0 mol% or more and 5.0 mol% or less, and the stabilizer content of the second layer exceeds 5.0 mol%. It is preferably 0 mol% or less, and the difference between the stabilizer content of the first layer and the stabilizer content of the second layer is preferably 0.7 mol% or more and 1.8 mo% or less. The yttria content of the layer is 4.0 mol% or more and 5.0 mol% or less, the yttria content of the second layer is more than 5.0 mol% and 6.0 mol% or less, and the yttria content of the first layer is It is more preferable that the difference between the yttria content of the second layer and that of the second layer is 0.7 mol% or more and 1.8 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, and when the stabilizer is yttria (Y ₂ O ₃ ), {Y ₂ O ₃ / (ZrO ₂ + Y ₂ O ₃ )} × 100 (mol%).

The sintered body of the present embodiment may contain alumina, and it is preferable that at least one zirconia layer contains alumina. The alumina content of the sintered body 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 sintered body. 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 layer is also in the same range as described above. The alumina content of each zirconia layer may affect the heat shrinkage behavior during the calcining stage. The alumina content of each zirconia layer is arbitrary, and each zirconia layer may have a different alumina content, but preferably has the same alumina content. When the alumina contents of the zirconia layers are different, the difference in the alumina contents of the adjacent zirconia layers is more than 0% by mass and 1.0% by mass or less, further more than 0% by mass and 0.5% by mass or less, and further. Can be exemplified to be more than 0% by mass and 0.03% by mass or less, and further 0.005% by mass or more and 0.01% by mass or less. For example, in the case of a zirconia layer composed of zirconia containing alumina (Al ₂ O ₃ ) and the stabilizer is yttria (Y ₂ O ₃ ), the alumina content is {Al ₂ O ₃ / (ZrO ₂ + Y ₂ O). It can be calculated as ₃ + Al ₂ O ₃ )} × 100 (mass%).

The sintered body of the present embodiment and each zirconia layer may not contain a colorant. On the other hand, in order to obtain an arbitrary coloration, the sintered body of the present embodiment may contain an element having a function of coloring zirconia (hereinafter, also referred to as “colorant”). The colorant may be an element having a function of coloring zirconia, and may be an element having a function of coloring zirconia and having a function of suppressing a phase transition. 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 iron, cobalt, manganese, praseodymium. , One or more selected from the group of gadium, terbium and erbium, more preferably one or more selected from the group of iron, cobalt and erbium.

The content of the colorant is 0% by mass or more and 0.3% by mass or less, preferably 0% by mass or more and 0.2% by mass or less, as the mass ratio of each colorant in terms of oxide to the mass of each zirconia layer. Can be exemplified.

The state of the colorant contained in the sintered body of the present embodiment is arbitrary, and at least one of an oxide state and a solid solution state in zirconia can be exemplified.

When two or more zirconia layers contain a colorant, the content and type thereof may differ between the zirconia layers.

The sintered body of the present embodiment preferably contains at least a zirconia layer containing zirconia having at least one tetragonal (T phase) and cubic (C phase) crystal phase, and at least mainly tetragonal crystals. It is more preferable to include a zirconia layer containing zirconia as a phase, and further preferably to include a zirconia layer containing zirconia having a tetragonal main phase and a zirconia layer containing zirconia having a cubic 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 sintered body.

The following conditions can be exemplified as the measurement conditions for the XRD pattern on the surface of the sintered 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 sintered body of the present embodiment has a density of 5.7 g / cm ³ or more and 6.3 g / cm ³ or less, preferably 5.9 g / cm ³ or more, as measured by a method according to JIS R 1634. It can be exemplified that it is 1 g / cm ³ or less. 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 sintered body of the present embodiment preferably contains at least a zirconia layer having a translucent feeling. Further, at least, the total light transmittance (hereinafter, also simply referred to as “total light transmittance”) for light having a wavelength of 600 nm at a sample thickness of 1.0 mm is 30% or more and 50% or less, and further 32% or more and 45% or less. Further, it is preferable to have a zirconia layer of 35% or more and 42% or less.

In the sintered body of the present embodiment, 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 1.5% or more and 5% or less. ..

The total light transmittance of the sintered body of the present embodiment 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 of the present embodiment 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 sintered body so as to have a sample thickness of 1 mm.

The total light transmittance is measured by a method according to JIS K 7361, and light having a wavelength of 600 nm is used as incident light, and can be obtained as the value of the total transmittance of the diffuse transmittance and the linear transmittance with respect to the incident light. A sample having a thickness of 1 mm and a surface roughness (Ra) ≤ 0.02 μm is used as a measurement sample, and light having a wavelength of 600 nm is applied to the sample using a general spectrophotometer (for example, V-650, manufactured by JASCO Corporation). The transmittance (diffuse transmittance and linear transmittance) of the sample is measured by irradiating and condensing the transmitted light with an integrating sphere, and this may be defined as the total light transmittance.

The sintered body of the present embodiment 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. 4 is a schematic view showing the measurement of the three-point bending strength of the sintered body (400) composed of two zirconia layers. The sintered body (400) is shown as a sintered body having a structure in which two zirconia layers having different layer thicknesses are laminated. In FIG. 4, 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. 4, the three-point bending strength may be measured by applying a load (41) so as to be perpendicular to the length of the measurement sample (400). The measurement sample may be arranged so that the load (41) is applied in the middle of the distance between the fulcrums (42). The distance between the fulcrums is 30 mm.

The sintered 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 dental materials for dentures such as crowns and bridges. It can be a dental material containing a sintered body in the form.

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

The manufacturing method of this embodiment is
It has a structure in which two or more powder composition layers composed of a powder composition containing a stabilizer containing zirconia and a binder are laminated, and at least, at least.
A first powder composition layer containing zirconia having a stabilizer content of 4 mol% or more and a binder, and the like.
Zirconia contained in the first powder composition layer and zirconia having different contents of stabilizers,
A second powder composition layer containing a binder and
With
A step of sintering 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 1200 ° C. or higher and 1600 ° C. or lower. It is a method for producing a sintered body, which is characterized by having.

Moreover, another manufacturing method of this embodiment is
It has a structure in which two or more powder composition layers composed of a powder composition containing a stabilizer containing zirconia and a binder are laminated, and at least, at least.
A first powder composition layer containing zirconia having a stabilizer content of 4 mol% or more and a binder, and the like.
A second powder composition layer containing zirconia contained in the first powder composition layer and a zirconia having a different content of a stabilizer, 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 is calcined at 800 ° C. or higher and lower than 1200 ° C. The process of making a calcined body and
A method for producing a sintered body, which comprises a step of sintering a calcined body at 1200 ° C. or higher and 1600 ° C. or lower.

Further, another manufacturing method of the present embodiment is described.
It has a structure in which two or more zirconia composition layers containing a stabilizer and containing zirconia having a necking structure are laminated, and at least
A first zirconia composition layer containing zirconia having a stabilizer content of 4 mol% or more,
A second zirconia composition layer containing zirconia having a different content of the stabilizer from the zirconia contained in the first zirconia composition layer, and a second zirconia composition layer containing zirconia.
It is a method for producing a sintered body, which comprises a step of sintering a calcined body comprising the above, at 1200 ° C. or higher and 1600 ° C. or lower.

The molded product used in the manufacturing method of the present embodiment is
It has a structure in which two or more powder composition layers composed of a powder composition containing a stabilizer containing zirconia and a binder are laminated, and at least, at least.
A first powder composition layer containing zirconia having a stabilizer content of 4 mol% or more and a binder, and the like.
A second powder composition layer containing zirconia contained in the first powder composition layer and a zirconia having a different content of a stabilizer, 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 main points different from the above-mentioned sintered body.

The molded product used in the manufacturing method of the present embodiment is
It has a structure in which two or more powder composition layers composed of a powder composition containing a stabilizer containing zirconia and a binder are laminated, and at least, at least.
A first powder composition layer containing zirconia having a stabilizer content of 4 mol% or more and a binder, and the like.
A second powder composition layer containing zirconia contained in the first powder composition layer and a zirconia having a different content of a stabilizer, 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 has a powder composition layer (hereinafter, also referred to as “powder layer”) composed of a powder composition containing a zirconia containing a stabilizer and a binder instead of having a zirconia layer. It has a structure equivalent to the laminated structure shown in 1 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.

The warp of the molded product is preferably 1.0 mm or less, more preferably 0.3 mm or less, further preferably 0.1 mm or less, and even more preferably 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 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 in the molded product and each powder layer is arbitrary, but it may be the same as the sintered body 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. To. 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 more than 0.01% by mass and 3% by mass or less, further 0.03% by mass or more and 2% by mass or less, and further 0.1% by mass or more and 1.2% by mass. Below, further, 0.12% by mass or more and 1% by mass or less, and further, 0.13% by mass or more and 0.5% by mass or less.

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 the product, after determining the total mass of the constituent components (for example, oxide-converted stabilizer, zirconia, and alumina) of the powder composition other than the binder, the weight ratio of the target binder to this is determined. Demanding and producing a powder composition can be mentioned.

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 the zirconia powder and the binder are granulated (hereinafter, also referred to as “granulated powder”), and is spray-dried. It is more preferable that it is a granulated powder (hereinafter, also referred to as “powder granule”) that has been granulated into granules.

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 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.

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

The calcined body used in the manufacturing method of the present embodiment is
It has a structure in which two or more zirconia composition layers containing zirconia containing a stabilizer and having a necking structure are laminated, and at least,
A first zirconia composition layer containing zirconia having a stabilizer content of 4 mol% or more,
A second zirconia composition layer containing zirconia having a different content of the stabilizer from the zirconia contained in the first zirconia composition layer, and a second zirconia composition layer containing zirconia.
It is a calcined body, which is equipped with.

The calcined body 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. 5, in the zirconia (51) 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 zirconia particles having a zirconia necking structure containing a stabilizer.

Instead of having a zirconia layer, the calcined product has a zirconia composition layer (hereinafter, also referred to as “composition layer”) containing zirconia having a stabilizer and having a necking structure, and FIG. Alternatively, it has a structure equivalent to the laminated structure shown in FIG.

The calcined body preferably has a warp of 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 calcined 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 calcined body 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 amount of deformation of the calcined product is preferably 1.0 or less, more preferably 0.5 or less, more preferably 0.2 or less, still more 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 calcined product is preferably in a state in which the zirconia in which the zirconia sol is heat-treated is heat-treated at a temperature lower than the sintering temperature, and the zirconia obtained by hydrolyzing the zirconium compound is calcined. 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 content of the stabilizer-containing zirconia stabilizer contained in the first composition layer (hereinafter, also referred to as “first composition layer”), the second composition layer (hereinafter, “second composition”). The content of the stabilizer-containing zirconia stabilizer contained in the "layer") and the stabilizer contained in the third composition layer (hereinafter, also referred to as "third composition layer"). The content of the stabilizer contained in the zirconia may be the same as the content of the stabilizer in the first layer, the second layer and the third layer, respectively.

The contents of the calcined body and the stabilizer of each composition layer are arbitrary, but may be the same as the sintered body of the present embodiment described above.

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

It can be exemplified that the calcined 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 calcined body may be a laminated body having 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 calcined body and each composition layer are opaque, and the total light transmittance 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 calcined body may have enough strength to prevent defects during processing such as CAD / CAM and cutting.

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 1500 ° 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.

Hereinafter, the sintered body of the present embodiment will be described with reference to Examples. However, the present invention is not limited to these examples.
(Density measurement)
The density of the molded body and the calcined body was determined from the weight measured by the weight measurement from the volume obtained by the dimensional measurement. For dimensional measurement, use a disk-shaped sample, measure the diameter of the upper end, the diameter of the lower end, and the thickness at 4 points each using a caliper, and measure the average value of the thickness and the average value of the diameter of the upper and lower ends. did.
The density of the sintered body was measured by a method according to JIS R 1634.

(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 was measured using a spectrophotometer (device name: V-650, manufactured by JASCO Corporation) by a method according to JIS K 7361. A disk-shaped sample was used for the measurement. Prior to the measurement, both sides of the sample were polished so that the sample thickness was 1 mm and the surface roughness (Ra) was 0.02 μm or less. The transmittance at each wavelength was measured by transmitting light having a wavelength of 220 to 850 nm through the sample and condensing it with an integrating sphere, and the transmittance at a wavelength of 600 nm was defined as the total light transmittance.

(Three-point bending strength)
The three-point bending strength was measured by a method according to JIS R 1601. The measurement sample had a length in the stacking direction and had a pillar shape having a width of 4 mm, a thickness of 3 mm, and a length of 45 mm. The measurement was performed with a distance between fulcrums of 30 mm and a load applied in the horizontal direction of the measurement sample.
(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. ..

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 5.5 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. Α-Alumina was mixed with the dried powder to prepare a mixed powder, and distilled water was added to the mixed powder to obtain a slurry, which was treated with a ball mill for 22 hours.
After the ball mill treatment, an acrylic acid-based binder (acrylic resin) was added to the slurry as a binder and mixed so that the weight ratio of the binder to the weight of the mixed powder in the slurry was 3.13% by mass. The mixed slurry was spray-dried at 180 ° C., containing 3.13% by mass of an acrylic acid-based binder (acrylic resin) and 0.05% by mass of alumina, and the balance consisting of 5.5 mol% yttria-containing zirconia, on average. Powder granules having an agglomeration diameter of 45 μm were obtained.

(Zirconia powder A2)
3. The acrylic acid-based binder was added in the same manner as the zirconia powder A1 except that the acrylic acid-based binder was added to the slurry and mixed so that the weight ratio of the binder to the weight of the slurry was 3.5% by mass. Powder granules containing 5% by mass and 0.05% by mass of alumina and having a balance of 5.5 mol% yttria-containing zirconia having an average aggregation diameter of 44 μm were obtained.
(Zirconia powder A3)
The acrylic acid-based binder was added in the same manner as the zirconia powder A1 except that the acrylic acid-based binder was added to the slurry and mixed so that the weight ratio of the binder to the weight of the slurry was 4.0% by mass. Powder granules containing 0.05% by mass and 0.05% by mass of alumina and having a balance of 5.5 mol% yttria-containing zirconia and an average aggregation diameter of 46 μm were obtained.
(Zirconia powder A4)
5.0 of the acrylic acid-based binder was added in the same manner as the zirconia powder A1 except that the acrylic acid-based binder was added to the slurry and mixed so that the weight ratio of the binder to the slurry weight was 5.0% by mass. Powder granules containing 0.05% by mass and 0.05% by mass of alumina and having a balance of 5.5 mol% yttria-containing zirconia and an average aggregation diameter of 46 μm were obtained.
(Zirconia powder A5)
The acrylic acid-based binder was added to the slurry in the same manner as in the zirconia powder A1 except that the acrylic acid-based binder was added to the slurry and mixed so that the weight ratio of the binder to the weight of the slurry was 6.0% by mass. Powder granules containing 0.05% by mass and 0.05% by mass of alumina and having a balance of 5.5 mol% yttria-containing zirconia having an average aggregation diameter of 45 μm were obtained.
(Zirconia powder A6)
Yttria chloride was added to the hydrated zirconia sol so that the yttria concentration was 5.2 mol%, and the acrylic acid-based binder was added so that the weight ratio of the binder to the slurry weight was 3.05% by mass. It contains 3.05% by mass of acrylic acid-based binder and 0.05% by mass of alumina, and the balance consists of 5.2 mol% yttria-containing zirconia in the same manner as zirconia powder A1 except that it is added to the slurry and mixed. , Powder granules having an average agglomeration diameter of 43 μm were obtained.
(Zirconia powder A7)
Yttria chloride was added to the hydrated zirconia sol so that the yttria concentration was 5.80 mol%, and the acrylic acid-based binder was added so that the weight ratio of the binder to the slurry weight was 3.08% by mass. It contains 3.08% by mass of acrylic acid-based binder and 0.05% by mass of alumina, and the balance is 5.8 mol% yttria-containing zirconia in the same manner as zirconia powder A1 except that it is added to the slurry and mixed. , Powder granules having an average agglomeration diameter of 44 μm were obtained.

(Zirconia powder B1)
A powder after drying is obtained in the same manner as the zirconia powder A1, and α-alumina and distilled water are mixed thereto to form a slurry, which is treated with a ball mill for 22 hours to contain 0.05% by mass of alumina. A slurry containing a powder containing zirconia containing 5.5 mol% yttria was obtained.
Further, a powder after drying was obtained in the same manner as the zirconia powder A1 except that yttria chloride was added to the hydrated zirconia sol so that the yttria concentration became 3.0 mol%, and α-alumina and distillation were obtained therein. Water was mixed to obtain a slurry, which was treated with a ball mill for 22 hours to obtain a powder containing 0.05% by mass of alumina and the balance of 3.0 mol% yttria-containing zirconia.
The two obtained slurries are mixed to obtain a slurry containing 0.05% by mass of alumina and a powder containing 4.0 mol% zirconia containing itria, and then the weight ratio of the binder to the weight of the slurry is 3.05% by mass. As described above, an acrylic acid-based binder was added to the slurry and mixed. The mixed slurry was spray-dried at 180 ° C., containing 3.05% by mass of an acrylic acid-based binder and 0.05% by mass of alumina, the balance consisting of 4.0 mol% yttria-containing zirconia, and an average aggregation diameter of 43 μm. Powdered granules were obtained.

(Zirconia powder B2)
Contains a slurry containing a powder containing 0.05% by mass of alumina and having a balance of 5.5 mol% yttria-containing zirconia, and a powder containing 0.05% by mass of alumina and having a balance of 2.5 mol% yttria-containing zirconia. The same method as for zirconia powder B1 except that the slurry was mixed and an acrylic acid-based binder was added to the slurry and mixed so that the weight ratio of the binder to the weight of the slurry was 3.08% by mass. Powder granules containing 3.08% by mass of an acrylic acid-based binder and 0.05% by mass of alumina and having a balance of 4.0 mol% yttria-containing zirconia and an average aggregation diameter of 46 μm were obtained.
(Zirconia powder B3)
Contains a slurry containing a powder containing 0.05% by mass of alumina and having a balance of 5.5 mol% yttria-containing zirconia, and a powder containing 0.05% by mass of alumina and having a balance of 2.5 mol% yttria-containing zirconia. The same method as for zirconia powder B1 except that the slurry was mixed and an acrylic acid-based binder was added to the slurry and mixed so that the weight ratio of the binder to the weight of the slurry was 2.0% by mass. Powder granules containing 2.0% by mass of an acrylic acid-based binder and 0.05% by mass of alumina and having a balance of 4.15 mol% yttria-containing zirconia and an average aggregation diameter of 45 μm were obtained.
(Zirconia powder B4)
The mixing ratio of both slurrys was changed so that the yttria content was 4.5 mol%, and an acrylic acid-based binder was added to the slurry so that the weight ratio of the binder to the weight of the slurry was 3.06% by mass. It contains 3.06% by mass of acrylic acid-based binder and 0.05% by mass of alumina, and the balance consists of 4.5 mol% yttria-containing zirconia in the same manner as zirconia powder B1 except that it is mixed, and the average aggregation diameter is 45 μm powder granules were obtained.

(Zirconia powder C1)
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 4.05 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. Α-Alumina was mixed with the dried powder to prepare a mixed powder, and distilled water was added to the mixed powder to obtain a slurry, which was treated with a ball mill for 22 hours.
After the ball mill treatment, an acrylic acid-based binder was added to the slurry and mixed so that the weight ratio of the binder to the weight of the mixed powder in the slurry was 3.30% by mass. The mixed slurry was spray-dried at 180 ° C., containing 3.30% by mass of an acrylic acid-based binder and 0.05% by mass of alumina, the balance consisting of 4.05 mol% yttria-containing zirconia, and an average aggregation diameter of 43 μm. Powdered granules were obtained.
(Zirconia powder C2)
Yttria chloride was added to the hydrated zirconia sol so that the yttria concentration was 4.10 mol%, and an acrylic acid-based binder was added to the slurry so that the weight ratio of the binder to the weight of the slurry was 3.20% by mass. It contains 3.20% by mass of acrylic acid-based binder and 0.05% by mass of alumina, and the balance consists of 4.10 mol% yttria-containing zirconia in the same manner as zirconia powder C1 except that it is added and mixed. Powder granules having an agglomeration diameter of 46 μm were obtained.
(Zirconia powder C3)
Yttria chloride was added to the hydrated zirconia sol so that the yttria concentration was 4.25 mol%, and an acrylic acid-based binder was added to the slurry so that the weight ratio of the binder to the weight of the slurry was 3.29% by mass. The same method as for zirconia powder C1 except that it was added and mixed, containing 3.29% by mass of an acrylic acid-based binder and 0.05% by mass of alumina, and the balance consisting of 4.25 mol% yttria-containing zirconia, on average. Powder granules having an agglomeration diameter of 44 μm were obtained.
(Zirconia powder C4)
Yttria chloride was added to the hydrated zirconia sol so that the yttria concentration was 4.00 mol%, α-alumina was not used, and the weight ratio of the binder to the slurry weight was 3.50% by mass. From zirconia containing 3.50% by mass and the balance of 4.00 mol% yttria in the same manner as for zirconia powder C1 except that an acrylic acid-based binder was added to the slurry and mixed. The powder granules having an average agglomeration diameter of 44 μm were obtained.
(Zirconia powder C5)
Yttria chloride was added to the hydrated zirconia sol so that the yttria concentration was 4.00 mol%, and the acrylic acid-based binder was added so that the weight ratio of the binder to the slurry weight was 3.50% by mass. It contains 3.50% by mass of acrylic acid-based binder and 0.05% by mass of alumina, and the balance consists of 4.00 mol% yttria-containing zirconia in the same manner as zirconia powder C1 except that it is added to the slurry and mixed. , Powder granules having an average agglomeration diameter of 46 μm were obtained.
(Zirconia powder C6)
Yttria chloride was added to the hydrated zirconia sol so that the yttria concentration was 4.00 mol%, α-alumina was mixed so that the alumina content was 0.10% by mass, and the slurry weight. The acrylic acid-based binder was added to the slurry in the same manner as that of the zirconia powder C1 except that the acrylic acid-based binder was added to the slurry so that the weight ratio of the binder to the weight of the binder was 3.50% by mass. And alumina in 0.10% by mass, the balance was made of zirconia containing 4.00 mol% yttria, and powder granules having an average aggregation diameter of 45 μm 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, and the mold was tapped to form a second powder layer, 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 composed of two layers, which was used as a molded product of this example. The stabilizer content of the first powder layer is 5.5 mol%, the stabilizer content of the second powder layer is 4.0 mol%, the difference in yttria content between layers is 1.50 mol%, and the binder. The difference in content (difference in binder amount) was 0.08% by mass.
The warp of the molded product was 0.06 mm, and the amount of deformation was 0.12.

(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.
The warp of the calcined body was 0.06 mm, and the amount of deformation was 0.12.

(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 warp of the sintered body was 0.06 mm, and the amount of deformation was 0.15. The stabilizer content of the sintered body was 4.75 mol%.

Example 2
A laminate was obtained in the same manner as in Example 1 except that zirconia powder A2 and zirconia powder B2 were used instead of zirconia powder A1 and zirconia powder B1, and this was used as a molded product of this example. The stabilizer content of the first powder layer is 5.5 mol%, the stabilizer content of the second powder layer is 4.0 mol%, the difference in yttria content between layers is 1.50 mol%, and the binder. The difference in content was 0.42% 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 warp is 0.04 mm for the molded body, 0.05 mm for the calcined body and 0.04 mm for the sintered body, and the amount of deformation is 0.08 for the molded body, 0.10 for the calcined body and the sintered body. Was 0.10.

Example 3
A laminate was obtained in the same manner as in Example 1 except that zirconia powder A4 and zirconia powder B2 were used instead of the zirconia powder A1 and the zirconia powder B1, respectively, and this was used as the molded product of the present example. The stabilizer content of the first powder layer is 5.5 mol%, the stabilizer content of the second powder layer is 4.0 mol%, the difference in yttria content between layers is 1.50 mol%, and the binder. The difference in content was 1.92% 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 warpage was less than the measurement limit (less than 0.03 mm) for the molded body, 0.04 mm for the calcined body, and less than the measurement limit (less than 0.03 mm) for the sintered body, and the amount of deformation was 0 for the calcined body. It was 09.

Example 4
A laminate was obtained in the same manner as in Example 1 except that zirconia powder A5 and zirconia powder B2 were used instead of zirconia powder A1 and zirconia powder B1, and this was used as a molded product of this example. The stabilizer content of the first powder layer is 5.5 mol%, the stabilizer content of the second powder layer is 4.0 mol%, the difference in yttria content between layers is 1.50 mol%, and the binder. The difference in content was 2.92% 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 warpage is 0.04 mm for the molded body, 0.03 mm for the calcined body, and less than the measurement limit (less than 0.03 mm) for the sintered body, and the amount of deformation is 0.08 for the molded body and 0 for the calcined body. It was .06.

From Examples 1 to 4, when the yttria content difference is 1.50 mol%, the warp in the case of a calcined product tends to be suppressed as the difference in the amount of the binder increases, and the amount of the binder. It was confirmed that the difference was 0.5% by mass or more and the warpage in the state of the sintered body was less than the measurement limit.

Example 5
A laminate was obtained in the same manner as in Example 1 except that zirconia powder B3 was used instead of zirconia powder B1, and this was used as a molded product of this example. The stabilizer content of the first powder layer is 5.5 mol%, the stabilizer content of the second powder layer is 4.15 mol%, the difference in yttria content between layers is 1.35 mol%, and the binder. The difference in content was 1.13% 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 warp is 0.04 mm for the molded body, 0.03 mm for the calcined body, and 0.03 mm for the sintered body, and the amount of deformation is 0.08 for the molded body, 0.06 for the calcined body, and the sintered body. Was 0.08.

Example 6
A laminate was obtained in the same manner as in Example 1 except that zirconia powder B4 was used instead of zirconia powder B1, and this was used as a molded product of this example. The stabilizer content of the first powder layer is 5.5 mol%, the stabilizer content of the second powder layer is 4.5 mol%, the difference in yttria content between layers is 1.0 mol%, and the binder. The difference in content was 0.07% 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 warp is 0.05 mm for the molded body, 0.05 mm for the calcined body, and 0.05 mm for the sintered body, and the amount of deformation is 0.10 for the molded body, 0.10 for the calcined body, and the sintered body. Was 0.13. The stabilizer content of the sintered body was 5.0 mol%.

Example 7
A laminate was obtained in the same manner as in Example 1 except that zirconia powder A3 and zirconia powder B4 were used instead of zirconia powder A1 and zirconia powder B1, and this was used as a molded product of this example. The stabilizer content of the first powder layer is 5.5 mol%, the stabilizer content of the second powder layer is 4.5 mol%, the difference in yttria content between layers is 1.0 mol%, and the binder. The difference in content was 0.94% 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 warpage is 0.04 mm for the molded body, 0.04 mm for the calcined body, and 0.03 mm for the sintered body, and the amount of deformation is 0.08 for the molded body, 0.08 for the calcined body, and the sintered body. Was 0.08.

Example 8
A laminate was obtained in the same manner as in Example 1 except that zirconia powder C1 was used instead of zirconia powder B1, and this was used as a molded product of this example. The stabilizer content of the first powder layer is 5.5 mol%, the stabilizer content of the second powder layer is 4.05 mol%, the difference in yttria content between layers is 1.45 mol%, and the binder. The difference in content was 0.2% 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 warp was less than the measurement limit (less than 0.03 mm) for all of the molded body, calcined body and sintered body.

Example 9
A laminate was obtained in the same manner as in Example 1 except that zirconia powder C2 was used instead of zirconia powder B1, and this was used as a molded product of this example. The stabilizer content of the first powder layer is 5.5 mol%, the stabilizer content of the second powder layer is 4.1 mol%, the difference in yttria content between layers is 1.4 mol%, and the binder. The difference in content was 0.1% 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 4.8 mol%.

The warpage is 0.03 mm for the molded body, 0.03 mm for the calcined body, and 0.04 mm for the sintered body, and the amount of deformation is 0.06 for the molded body, 0.06 for the calcined body, and the sintered body. Was 0.10.

Example 10
A laminate was obtained in the same manner as in Example 1 except that zirconia powder C3 was used instead of zirconia powder B1, and this was used as a molded product of this example. The stabilizer content of the first powder layer is 5.5 mol%, the stabilizer content of the second powder layer is 4.25 mol%, the difference in yttria content between layers is 1.25 mol%, and the binder. The difference in content was 0.19% 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 warpage is less than the measurement limit (less than 0.03 mm) for the molded body, 0.03 mm for the calcined body and 0.03 mm for the sintered body, and the amount of deformation is 0.06 for the calcined body and 0.03 mm for the sintered body. It was 0.08.

Density molded body is 3.28 g / cm ³ and calcined body is 3.22 g / cm ^3, the density of the sintered body was 6.06 g / cm ^3.

Example 11
A laminate was obtained in the same manner as in Example 10 except that the pressure for uniaxial pressure press molding was set to 19.6 MPa, and this was used as the molded product of this example.

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 warp is less than the measurement limit (less than 0.03 mm) for the molded body, 0.03 mm for the calcined body and 0.05 mm for the sintered body, and the amount of deformation is 0.07 for the calcined body and 0.07 for the sintered body. It was 0.14.

Density molded body is 3.25 g / cm ³ and calcined body is 3.19 g / cm ^3, the density of the sintered body was 6.06 g / cm ^3.

Example 12
A laminate was obtained in the same manner as in Example 10 except that the pressure for uniaxial pressure press molding was 98 MPa, and this was used as the molded product of this example.

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 warp was less than the measurement limit (less than 0.03 mm) for all of the molded body, calcined body and sintered body.

The density of the molded product was 3.35 g / cm ³ and that of the calcined product was 3.29 g / cm ³ , and the density of the sintered body was 6.06 g / cm ³ .

From Examples 10 to 12, it can be seen that the density of the molded body and the calcined body tends to increase as the pressure of the uniaxial pressure press molding increases. At the same time, it can be seen that the warpage of the calcined body and the sintered body tends to be suppressed.

Example 13
A laminate was obtained in the same manner as in Example 10 except that a mold having an inner diameter of 110 mm was used and the pressure for uniaxial pressure press molding was set to 98 MPa, and this was used as the molded product of this example.

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

From Examples 12 and 13, it can be seen that there is no difference (more accurately, the amount of change) in the warpage of the molded body, the calcined body and the sintered body due to the difference in the dimensions of the laminated body.

The sintered body obtained in each of the examples also had a change in translucency between the uppermost layer and the lowermost layer, and exhibited a texture close to that of natural teeth.

Example 14
Lamination is performed in the same manner as in Example 1 except that a mold having an inner diameter of 110 mm is used, the pressure for uniaxial pressure press molding is 19.6 MPa, and zirconia powder C4 is used instead of zirconia powder B1. A body was obtained, and this was used as a molded body of this example. The stabilizer content of the first powder layer is 5.5 mol%, the stabilizer content of the second powder layer is 4.0 mol%, the difference in yttria content between layers is 1.5 mol%, and the binder. The difference in content was 0.4% 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 4.75 mol%.

The warpage is 0.05 mm for the molded body, 0.11 mm for the calcined body, and less than the measurement limit (less than 0.03 mm) for the sintered body, and the amount of deformation is 0.05 for the molded body and 0 for the calcined body. It was 11．

Example 15
Lamination is performed in the same manner as in Example 1 except that a mold having an inner diameter of 110 mm is used, the pressure for uniaxial pressure press molding is 19.6 MPa, and zirconia powder C5 is used instead of zirconia powder B1. A body was obtained, and this was used as a molded body of this example. The stabilizer content of the first powder layer is 5.5 mol%, the stabilizer content of the second powder layer is 4.0 mol%, the difference in yttria content between layers is 1.5 mol%, and the binder. The difference in content was 0.37% 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 4.75 mol%.

The warpage was 0.05 mm for the molded body, 0.14 mm for the calcined body, and less than the measurement limit (less than 0.03 mm) for the sintered body, and the amount of deformation was 0.05 for the molded body and 0 for the calcined body. It was 11．

Example 16
The same method as in Example 1 except that a die having an inner diameter of 110 mm was used, the pressure for uniaxial pressure press molding was set to 19.6 MPa, and zirconia powder C6 was used instead of zirconia powder B1. A laminated body was obtained in 1 and this was used as a molded body of this example. The stabilizer content of the first powder layer is 5.5 mol%, the stabilizer content of the second powder layer is 4.0 mol%, the difference in yttria content between layers is 1.5 mol%, and the binder. The difference in content was 0.4% 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 4.75 mol%.

The warpage is 0.05 mm for the molded body, 0.15 mm for the calcined body, and less than the measurement limit (less than 0.03 mm) for the sintered body, and the amount of deformation is 0.05 for the molded body and 0 for the calcined body. It was .15.

As compared with Examples 14 to 16, as the alumina content of the layer having a low stabilizer content decreased, the warp of the calcined body became smaller, but the warp magnitude of the molded body and the sintered body did not change. It was.

Example 17
Same as Example 1 except that a die having an inner diameter of 110 mm was used, the pressure for uniaxial pressure press molding was 98 MPa, and zirconia powders A7 and C5 were used instead of zirconia powders A1 and B1. A laminated body was obtained by the above-mentioned method, and this was used as a molded body of this example. The stabilizer content of the first powder layer is 5.8 mol%, the stabilizer content of the second powder layer is 4.0 mol%, the difference in yttria content between layers is 1.8 mol%, and the binder. The difference in content was 0.42% 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 4.9 mol%.

The warp was 0.04 mm for the calcined body, less than the measurement limit (less than 0.03 mm) for the molded body and the sintered body, and the deformation amount was 0.03 for the calcined body.

Example 18
Same as Example 1 except that a die having an inner diameter of 110 mm was used, the pressure for uniaxial pressure press molding was 98 MPa, and zirconia powders A6 and C5 were used instead of zirconia powders A1 and B1. A laminated body was obtained by the above method, and this was used as a molded product of this example. The stabilizer content of the first powder layer is 5.2 mol%, the stabilizer content of the second powder layer is 4.0 mol%, the difference in yttria content between layers is 1.2 mol%, and the binder. The difference in content was 0.45% 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 4.6 mol%.

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

Comparative Example 1
A mold having an inner diameter of 110 mm was filled with 25 g of zirconia powder composed of zirconia containing 4.25 mol% yttria, and then the mold was tapped to form a first powder layer. The same amount of zirconia powder consisting of zirconia containing 4.25 mol% yttria is filled on the first powder layer, and the mold is tapped to form the second powder layer, and then uniaxial pressure press molding is performed at a pressure of 98 MPa. It was. 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% by mass.

When the calcined body and the sintered body were produced by the same method as in Example 1 except that the molded body was used, the warpage was less than the measurement limit (<0.03 mm) in both cases.

No warpage occurred in the calcined product of this comparative example in which the yttria content of the first layer and the second layer was the same. Moreover, the obtained sintered body did not have a change in translucency.

Comparative Example 2
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 5.5 mol% of yttria-containing zirconia, and the crystal phase thereof is from tetragonal and cubic crystals, with the main phase being cubic. It was. The total light transmittance of the sintered body was 37.5%, and the three-point bending strength was 600 MPa.

Reference example 2
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% of yttria-containing zirconia, and the crystal phase thereof is from tetragonal and cubic crystals, with the main phase being tetragonal. It was. The total light transmittance of the sintered body was 36%, and the three-point bending strength was 1100 MPa.

Reference example 3
A mold having an inner diameter of 48 mm was filled with zirconia powder B4, 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 contained 0.05% by mass of alumina and the balance was 4.5 mol% of yttria-containing zirconia, and the total light transmittance was 37%.

100, 200, 300, 400: Zirconia sintered body 11, 21: First layer 12, 22: Second layer 23: Third layer 32A, 32B: Cycness gauge 33: Sintered body size 41: Load 42: Support point Distance 51: Zirconia with a necking structure

Claims (18)

It has a structure in which two or more zirconia layers containing zirconia containing a stabilizer are laminated, and at least
A first zirconia layer containing zirconia having a stabilizer content of 4 mol% or more,
A second zirconia layer containing zirconia contained in the first zirconia layer and a zirconia having a different content of the stabilizer,
A sintered body characterized by comprising. The sintered body according to claim 1, wherein the content of the stabilizer-containing zirconia stabilizer contained in the second zirconia layer is 1.5 mol% or more and 7.0 mol% or less. The sintered body according to claim 1 or 2, wherein the content of the stabilizer-containing zirconia stabilizer contained in the second zirconia layer is 5.0 mol% or more and 7.0 mol% or less. The sintered body according to any one of claims 1 to 3, wherein the content of the stabilizer-containing zirconia stabilizer contained in the first zirconia layer is 4.0 mol% or more and 6.0 mol% or less. .. The sintering according to any one of claims 1 to 4, wherein the difference between the stabilizer content of the first zirconia layer and the stabilizer content of the second zirconia layer is 0.2 mol% or more. body. The stabilizer according to any one of claims 1 to 5, wherein the stabilizer is one or more selected from the group of yttria (Y ₂ O ₃ ), calcia (CaO), magnesia (MgO) and ceria (CeO ₂ ). Sintered body. The sintered body according to any one of claims 1 to 6, wherein at least one of the zirconia layers contains alumina. The sintered body according to any one of claims 1 to 7, wherein the warp measured by using a feeler gauge conforming to JIS B 7524: 2008 is 1.0 mm or less. The sintered body according to any one of claims 1 to 8, wherein the density 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. The sintered body according to any one of claims 1 to 9, which has a zirconia layer having a total light transmittance of 30% or more and 50% or less with respect to light having a wavelength of 600 nm at a sample thickness of 1.0 mm. The sintered body according to any one of claims 1 to 10, wherein the three-point bending strength measured by a method according to JIS R 1601 is 500 MPa or more. It has a structure in which two or more powder composition layers composed of a powder composition containing a stabilizer containing zirconia and a binder are laminated, and at least, at least.
A first powder composition layer containing zirconia having a stabilizer content of 4 mol% or more and a binder, and the like.
A second powder composition layer containing zirconia contained in the first powder composition layer and a zirconia having a different content of a stabilizer, and a binder.
With
A step of sintering 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 1200 ° C. or higher and 1600 ° C. or lower. The method for producing a sintered body according to any one of claims 1 to 11, wherein the sintered body has. It has a structure in which two or more powder composition layers composed of a powder composition containing a stabilizer containing zirconia and a binder are laminated, and at least, at least.
A first powder composition layer containing zirconia having a stabilizer content of 4 mol% or more and a binder, and the like.
A second powder composition layer containing zirconia contained in the first powder composition layer and a zirconia having a different content of a stabilizer, 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 is calcined at 800 ° C. or higher and lower than 1200 ° C. The process of making a calcined body and
The method for producing a sintered body according to any one of claims 1 to 11, further comprising a step of sintering the calcined body at 1200 ° C. or higher and 1600 ° C. or lower. The manufacturing method according to claim 12 or 13, wherein the warpage of the molded product measured using a feeler gauge conforming to JIS B 7524: 2008 is 1.0 mm or less. The production method according to any one of claims 12 to 14, 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 any one of claims 12 to 15, wherein the powder composition contained in the powder composition layer is a powder in a granulated state. The production method according to any one of claims 12 to 16, wherein the density of the molded product is 2.4 g / cm ³ or more and 3.7 g / cm ³ or less. A dental material containing the sintered body according to any one of claims 1 to 11.