阅读说明：本技术 包含荧光剂的氧化锆烧结体 (Zirconia sintered body containing fluorescent agent ) 是由 工藤恭敬 加藤牧子 冈田浩一 于 2018-07-27 设计创作，主要内容包括：本发明提供包含荧光剂且透光性和强度优异的氧化锆烧结体、能够获得该氧化锆烧结体的氧化锆成形体和氧化锆煅烧体。本发明涉及氧化锆烧结体,其为包含荧光剂的氧化锆烧结体,其包含4.5~9.0摩尔%的氧化钇,所述氧化锆烧结体的结晶粒径为180nm以下,3点弯曲强度为500MPa以上；涉及氧化锆成形体,其为包含荧光剂的氧化锆成形体,其包含4.5~9.0摩尔%的氧化钇,所述氧化锆成形体在常压下以1100℃烧结2小时后的3点弯曲强度为500MPa以上,在常压下以1100℃烧结2小时后的结晶粒径为180nm以下；涉及氧化锆煅烧体,其为包含荧光剂的氧化锆煅烧体,其包含4.5~9.0摩尔%的氧化钇,所述氧化锆煅烧体在常压下以1100℃烧结2小时后的3点弯曲强度为500MPa以上,在常压下以1100℃烧结2小时后的结晶粒径为180nm以下。(The invention provides a zirconia sintered body which contains a fluorescent agent and has excellent light transmittance and strength, a zirconia formed body and a zirconia calcined body which can obtain the zirconia sintered body. The present invention relates to a zirconia sintered body containing a fluorescent agent, which contains 4.5 to 9.0 mol% of yttria, and has a crystal grain size of 180nm or less and a 3-point bending strength of 500MPa or more; disclosed is a zirconia molded body containing a fluorescent agent, which contains 4.5-9.0 mol% of yttria, wherein the zirconia molded body has a 3-point bending strength of 500MPa or more after being sintered at 1100 ℃ for 2 hours under normal pressure, and a crystal grain diameter of 180nm or less after being sintered at 1100 ℃ for 2 hours under normal pressure; disclosed is a calcined zirconia body containing a fluorescent agent, which contains 4.5-9.0 mol% of yttria, wherein the calcined zirconia body has a 3-point bending strength of 500MPa or more after being sintered at 1100 ℃ for 2 hours under normal pressure, and a crystal grain size of 180nm or less after being sintered at 1100 ℃ for 2 hours under normal pressure.)

1. A zirconia sintered body containing a fluorescent agent, which contains 4.5 to 9.0 mol% of yttria, and which has a crystal grain diameter of 180nm or less and a 3-point bending strength of 500MPa or more.

2. The zirconia sintered body according to claim 1, wherein the fluorescent agent contains a metal element, and the content of the fluorescent agent is 0.001 to 1 mass% in terms of an oxide of the metal element with respect to the mass of the zirconia.

3. The zirconia sintered body according to claim 1 or 2, wherein a transmittance of light having a wavelength of 700nm at a thickness of 0.5mm is 40% or more.

4. The zirconia sintered body according to any one of claims 1 to 3, wherein the main crystal phase is cubic.

5. The zirconia sintered body according to any one of claims 1 to 4, wherein the ratio of a monoclinic phase to tetragonal and cubic crystals after immersion in hot water at 180 ℃ for 5 hours is 5% or less.

6. The zirconia sintered body according to any one of claims 1 to 5, which is a dental material.

7. The zirconia sintered body according to claim 6, which is a prosthesis for molar occlusal surfaces or a prosthesis for anterior incisor end portions.

8. A zirconia molded body containing a fluorescent agent, which contains 4.5 to 9.0 mol% of yttria, wherein the zirconia molded body has a 3-point bending strength of 500MPa or more after being sintered at 1100 ℃ for 2 hours under normal pressure, and a crystal grain diameter of 180nm or less after being sintered at 1100 ℃ for 2 hours under normal pressure.

9. The zirconia shaped body of claim 8 formed from zirconia particles.

10. The zirconia molded body according to claim 8 or 9, wherein the fluorescent agent contains a metal element, and the content of the fluorescent agent is 0.001 to 1 mass% in terms of an oxide of the metal element with respect to the mass of the zirconia.

11. The zirconia molded body according to any one of claims 8 to 10, wherein the transmittance of light having a wavelength of 700nm at a thickness of 0.5mm after firing at 1100 ℃ for 2 hours under normal pressure is 40% or more.

12. A calcined zirconia body containing a fluorescent agent, which contains 4.5 to 9.0 mol% of yttria, wherein the calcined zirconia body has a 3-point bending strength of 500MPa or more after being sintered at 1100 ℃ for 2 hours under normal pressure, and a crystal grain size of 180nm or less after being sintered at 1100 ℃ for 2 hours under normal pressure.

13. The calcined zirconia body according to claim 12, which is obtained by calcining a zirconia compact formed of zirconia particles.

14. The calcined zirconia body according to claim 12 or 13, wherein the fluorescent agent contains a metal element, and the content of the fluorescent agent is 0.001 to 1% by mass in terms of an oxide of the metal element relative to the mass of the zirconia.

15. The calcined zirconia according to any one of claims 12 to 14, wherein the transmittance of light having a wavelength of 700nm at a thickness of 0.5mm after firing at 1100 ℃ for 2 hours under normal pressure is 40% or more.

16. A method for producing the zirconia molded body according to any one of claims 8 to 11, comprising a molding step of molding zirconia particles containing 4.5 to 9.0 mol% of yttria and having an average primary particle diameter of 20nm or less.

17. The manufacturing method according to claim 16, further comprising a step of mixing a slurry containing zirconia particles with a fluorescent agent in a liquid state.

18. The manufacturing method according to claim 16 or 17, wherein the forming step is a step of slip casting a slurry containing the zirconia particles and the fluorescent agent.

19. The manufacturing method according to claim 16 or 17, wherein the forming process is a process of gel-casting the slurry containing the zirconia particles and the fluorescent agent.

20. The manufacturing method according to claim 16 or 17, wherein the forming step is a step of press-forming a powder containing the zirconia particles and the fluorescent agent.

21. The production method according to claim 16 or 17, wherein the molding step is a step of molding a composition containing the zirconia particles, the fluorescent agent, and the resin.

22. The production method according to claim 16 or 17, wherein the molding step is a step of polymerizing a composition containing the zirconia particles, the fluorescent agent, and the polymerizable monomer.

23. The manufacturing method according to claim 22, wherein the forming process is a photo-forming process.

24. A method for producing the calcined zirconia body according to any one of claims 12 to 15, comprising the step of calcining the zirconia compact according to any one of claims 8 to 11 or the zirconia compact obtained by the production method according to any one of claims 16 to 23.

25. The production method according to claim 24, wherein the calcination is performed at 300 ℃ or higher and less than 900 ℃.

26. A method for producing the zirconia sintered body according to any one of claims 1 to 7, comprising a step of sintering the zirconia molded body according to any one of claims 8 to 11 or the zirconia molded body obtained by the production method according to any one of claims 16 to 23 under normal pressure.

27. The method according to claim 26, wherein the sintering is performed at 900 ℃ or higher and 1200 ℃ or lower.

28. A method for producing the zirconia sintered body according to any one of claims 1 to 7, comprising a step of sintering the zirconia calcined body according to any one of claims 12 to 15 or the zirconia calcined body obtained by the production method according to claim 24 or 25 under normal pressure.

29. The production method according to claim 28, wherein the sintering is performed at 900 ℃ or higher and 1200 ℃ or lower.

Technical Field

The present invention relates to a zirconia sintered body and the like containing a fluorescent agent.

Background

In recent years, zirconia sintered bodies containing yttria have been used for dental materials such as dental prostheses. These dental prostheses are in most cases produced by the following method: or by press-molding zirconia particles or molding the particles using a slurry or a composition containing zirconia particles to prepare a zirconia compact having a desired shape such as a disk shape or a prism shape, followed by calcining the compact to prepare a calcined body (polishing blank), cutting (polishing) the calcined body into a desired shape of a dental prosthesis, and further sintering the calcined body.

Known to date are: when the amount of yttria contained in the zirconia sintered body is set to an amount exceeding 4 mol%, the light transmittance is improved (for example, see patent document 1). In general, when the content of yttrium oxide is set high as described above, the strength such as bending strength is likely to be reduced due to the improvement of light transmittance. As a method for improving the strength reduction, for example, a method of reducing the crystal grain size of the zirconia sintered body by using zirconia grains having a small grain size or the like is conceivable.

However, the authigenic human teeth are fluorescent. Therefore, if the dental prosthesis does not have fluorescence, there is a problem as follows: in an ultraviolet irradiation environment such as in an entertainment facility performing a performance under black light, for example, only a portion of the dental prosthesis does not fluoresce and looks like a tooth is lost. In order to solve such a problem, it is conceivable to include a fluorescent agent in the dental prosthesis. As a zirconia sintered body containing a fluorescent agent, for example, a sintered body described in patent document 2 is known.

Disclosure of Invention

Problems to be solved by the invention

The present inventors have studied to find that a zirconia sintered body containing 4.5 to 9.0 mol% of yttria and having a crystal grain size of 180nm or less and excellent in light transmittance and strength further contains a fluorescent agent: when such a zirconia sintered body is simply made of a fluorescent agent, there is a problem that the strength is significantly reduced and the light transmittance is also significantly reduced compared to the expected strength.

Accordingly, an object of the present invention is to provide a zirconia sintered body excellent in both light transmittance and strength despite containing a fluorescent agent, a zirconia molded body and a zirconia calcined body which can be provided to such a zirconia sintered body, and a production method which can easily produce them.

Means for solving the problems

The present inventors have made intensive studies to achieve the above object, and as a result, have found that: by adjusting the method of mixing the fluorescent agent, etc., a novel zirconia sintered body which has excellent light transmittance and strength and which has not existed so far can be obtained. And found that: such zirconia sintered body is particularly suitable as a dental material such as a dental prosthesis, and is extremely useful not only as a dental prosthesis used for a cervical part of a tooth but also as a dental prosthesis used for an occlusal surface of a molar tooth and a front tooth cutting end portion (front cutting end portion). The present inventors have further studied based on these findings, and have completed the present invention.

That is, the present invention relates to the following [1] to [29 ].

[1] A zirconia sintered body containing a fluorescent agent, which contains 4.5 to 9.0 mol% of yttria, and which has a crystal grain diameter of 180nm or less and a 3-point bending strength of 500MPa or more.

[2] The zirconia sintered body according to [1], wherein the fluorescent agent contains a metal element, and the content of the fluorescent agent is 0.001 to 1% by mass in terms of an oxide of the metal element with respect to the mass of the zirconia.

[3] The zirconia sintered body according to [1] or [2], wherein the transmittance of light having a wavelength of 700nm at a thickness of 0.5mm is 40% or more.

[4] The zirconia sintered body according to any one of [1] to [3], wherein the main crystal phase is a cubic crystal.

[5] The zirconia sintered body according to any one of [1] to [4], wherein the ratio of a monoclinic phase to tetragonal and cubic crystals after immersion in hot water at 180 ℃ for 5 hours is 5% or less.

[6] The zirconia sintered body according to any one of [1] to [5], which is a dental material.

[7] The zirconia sintered body according to [6], which is a prosthesis for molar occlusal surfaces or a prosthesis for anterior incisor end portions.

[8] A zirconia molded body containing a fluorescent agent, comprising 4.5 to 9.0 mol% of yttria, wherein the zirconia molded body has a 3-point bending strength of 500MPa or more after being sintered at 1100 ℃ for 2 hours under normal pressure and a crystal grain diameter of 180nm or less after being sintered at 1100 ℃ for 2 hours under normal pressure.

[9] The zirconia molded body according to [8], which is formed of zirconia particles.

[10] The zirconia molded body according to [8] or [9], wherein the fluorescent agent contains a metal element, and the content of the fluorescent agent is 0.001 to 1% by mass in terms of an oxide of the metal element relative to the mass of the zirconia.

[11] The zirconia molded body according to any one of [8] to [10], wherein a transmittance of light having a wavelength of 700nm at a thickness of 0.5mm after firing at 1100 ℃ for 2 hours under normal pressure is 40% or more.

[12] A calcined zirconia body containing a fluorescent agent, which contains 4.5 to 9.0 mol% of yttria, wherein the calcined zirconia body has a 3-point bending strength of 500MPa or more after being sintered at 1100 ℃ for 2 hours under normal pressure, and a crystal grain size of 180nm or less after being sintered at 1100 ℃ for 2 hours under normal pressure.

[13] The calcined zirconia body according to [12], which is obtained by calcining a zirconia compact comprising zirconia particles.

[14] The calcined zirconia product according to [12] or [13], wherein the fluorescent agent contains a metal element, and the content of the fluorescent agent is 0.001 to 1% by mass in terms of an oxide of the metal element relative to the mass of the zirconia.

[15] The calcined zirconia body according to any one of [12] to [14], wherein the transmittance of light having a wavelength of 700nm at a thickness of 0.5mm after sintering at 1100 ℃ for 2 hours under normal pressure is 40% or more.

[16] A method for producing the zirconia molded body according to any one of [8] to [11], comprising a molding step of molding zirconia particles containing 4.5 to 9.0 mol% of yttria and having an average primary particle diameter of 20nm or less.

[17] The production method according to [16], further comprising a step of mixing a slurry containing zirconia particles with a fluorescent agent in a liquid state.

[18] The production method according to [16] or [17], wherein the molding step is a step of slip casting a slurry containing the zirconia particles and the fluorescent agent.

[19] The production method according to [16] or [17], wherein the forming step is a step of gel-casting the slurry containing the zirconia particles and the fluorescent agent.

[20] The production method according to [16] or [17], wherein the molding step is a step of press-molding a powder containing the zirconia particles and the fluorescent agent.

[21] The production method according to [16] or [17], wherein the molding step is a step of molding a composition containing the zirconia particles, the fluorescent agent, and the resin.

[22] The production method according to [16] or [17], wherein the molding step is a step of polymerizing a composition containing the zirconia particles, the fluorescent agent, and the polymerizable monomer.

[23] The production method according to [22], wherein the molding step is a photo-molding step.

[24] A method for producing the zirconia calcined body according to any one of [12] to [15], comprising the step of calcining the zirconia molded body according to any one of [8] to [11] or the zirconia molded body obtained by the production method according to any one of [16] to [23 ].

[25] The production method according to [24], wherein the calcination is performed at 300 ℃ or more and less than 900 ℃.

[26] A method for producing the zirconia sintered body according to any one of [1] to [7], comprising a step of sintering the zirconia molded body according to any one of [8] to [11] or the zirconia molded body obtained by the production method according to any one of [16] to [23] under normal pressure.

[27] The production method according to [26], wherein the sintering is performed at 900 ℃ or higher and 1200 ℃ or lower.

[28] A method for producing the zirconia sintered body according to any one of [1] to [7], comprising a step of sintering the zirconia calcined body according to any one of [12] to [15] or the zirconia calcined body obtained by the production method according to [24] or [25] under normal pressure.

[29] The production method according to [28], wherein the sintering is performed at 900 ℃ or higher and 1200 ℃ or lower.

Effects of the invention

According to the present invention, a zirconia sintered body excellent in both light transmittance and strength despite containing a fluorescent agent, a zirconia molded body and a zirconia calcined body which can be provided to such a zirconia sintered body, and a production method which can easily produce them can be provided.

Detailed Description

Hereinafter, embodiments of the present invention will be described. The present invention is not limited to the following description.

[ zirconia sintered body ]

The zirconia sintered body of the present invention contains a fluorescent agent. The zirconia sintered body has fluorescence due to the inclusion of a fluorescent agent. The kind of the fluorescent agent is not particularly limited, and 1 or 2 or more kinds of fluorescent agents that can fluoresce under light of an arbitrary wavelength can be used. As such a phosphor, a phosphor containing a metal element is cited. Examples of the metal element include Ga, Bi, Ce, Nd, Sm, Eu, Gd, Tb, Dy, and Tm. The phosphor may contain 1 of these metal elements alone, or 2 or more. Among these metal elements, Ga, Bi, Eu, Gd, and Tm are preferable, and Bi and Eu are more preferable, in order to more significantly exert the effects of the present invention. Examples of the fluorescent agent used for producing the zirconia sintered body of the present invention include oxides, hydroxides, acetates, nitrates and the like of the above-mentioned metal elements. Further, the fluorescent agent may be Y₂SiO₅:Ce、Y₂SiO₅:Tb、(Y,Gd,Eu)BO₃、Y₂O₃:Eu、YAG:Ce、ZnGa₂O₄:Zn、BaMgAl₁₀O₁₇Eu, etc.

The content of the fluorescent agent in the zirconia sintered body is not particularly limited, and may be appropriately adjusted depending on the type of the fluorescent agent, the use of the zirconia sintered body, and the like, but from the viewpoint of being preferably usable as a dental prosthesis, and the like, the content is preferably 0.001 mass% or more, more preferably 0.005 mass% or more, further preferably 0.01 mass% or more, and further preferably 1 mass% or less, more preferably 0.5 mass% or less, further preferably 0.1 mass% or less, in terms of oxide of the metal element contained in the fluorescent agent, with respect to the mass of the zirconia contained in the zirconia sintered body. When the content is not less than the lower limit, the fluorescence is comparable to that of a human natural tooth, and when the content is not more than the upper limit, the decrease in light transmittance and strength can be suppressed.

The zirconia sintered body of the present invention may contain a colorant. A colored zirconia sintered body is formed by including a colorant in the zirconia sintered body. The kind of the colorant is not particularly limited, and a known pigment generally used for coloring ceramics, a known liquid colorant for dentistry, and the like can be used. Examples of the coloring agent include coloring agents containing a metal element, and specifically include oxides, complex oxides, and salts containing a metal element such as iron, vanadium, praseodymium, erbium, chromium, nickel, and manganese. Further, commercially available colorants may be used, and for example, Prettau Colourliquid manufactured by Zirkonzahn company may be used. The zirconia sintered body may contain 1 kind of colorant, and may contain 2 or more kinds of colorants.

The content of the colorant in the zirconia sintered body is not particularly limited, and may be appropriately adjusted depending on the kind of the colorant, the use of the zirconia sintered body, and the like, but from the viewpoint of being preferably usable as a dental prosthesis, and the like, the content is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, further preferably 0.01% by mass or more, and further preferably 5% by mass or less, more preferably 1% by mass or less, further preferably 0.5% by mass or less, and may be 0.1% by mass or less, and further may be 0.05% by mass or less, in terms of an oxide of a metal element contained in the colorant, with respect to the mass of the zirconia contained in the zirconia sintered body.

According to the present invention, a zirconia sintered body excellent in light transmittance despite containing a fluorescent agent can be obtained. In order to adjust the light transmittance of the zirconia sintered body, the zirconia sintered body of the present invention may contain a light transmittance adjuster. Specific examples of the light transmittance adjuster include alumina, titanium oxide, silica, zircon, lithium silicate, and lithium disilicate. The zirconia sintered body may contain 1 kind of light transmittance adjusting agent, or may contain 2 or more kinds of light transmittance adjusting agents.

The content of the light transmittance adjusting agent in the zirconia sintered body is not particularly limited, and may be appropriately adjusted depending on the kind of the light transmittance adjusting agent, the use of the zirconia sintered body, and the like, and is preferably 0.1% by mass or less with respect to the mass of zirconia contained in the zirconia sintered body from the viewpoint of being preferably used as a dental prosthesis, and the like.

The zirconia sintered body of the present invention contains 4.5 to 9.0 mol% of yttria. When the content of yttria in the zirconia sintered body is less than 4.5 mol%, sufficient light transmittance cannot be obtained. Further, when the content of yttria in the zirconia sintered body exceeds 9.0 mol%, the strength is lowered. The content of yttria in the zirconia sintered body is preferably 5.0 mol% or more, more preferably 5.5 mol% or more, and further preferably 8.0 mol% or less, more preferably 7.0 mol% or less, from the viewpoint of obtaining a zirconia sintered body having more excellent light transmittance and strength. The content of yttria in the zirconia sintered body is a ratio (mol%) of the number of moles of yttria to the total number of moles of zirconia and yttria.

The crystal grain size of the zirconia sintered body of the present invention is 180nm or less. When the crystal grain size exceeds 180nm, sufficient light transmittance cannot be obtained. The crystal grain size is preferably 140nm or less, more preferably 120nm or less, further preferably 115nm or less, and may be 110nm or less, from the viewpoint of obtaining a zirconia sintered body having more excellent light transmittance. The lower limit of the crystal grain size is not particularly limited, and the crystal grain size may be, for example, 50nm or more, and further 100nm or more. The crystal grain size in the zirconia sintered body can be determined as an average value of each circle equivalent diameter (diameter of a perfect circle of the same area) by taking a field emission scanning electron microscope (FE-SEM) photograph of a cross section of the zirconia sintered body, selecting 10 arbitrary grains present in the taken image thereof, and calculating the average value.

The zirconia sintered body of the present invention is excellent in strength despite containing a fluorescent agent. The zirconia sintered body of the present invention has a 3-point bending strength of 500MPa or more, preferably 600MPa or more, more preferably 650MPa or more, further preferably 700MPa or more, and particularly preferably 800MPa or more. By providing the zirconia sintered body of the present invention with such 3-point bending strength, for example, when used as a dental prosthesis, it is possible to suppress breakage in the oral cavity and the like. The upper limit of the 3-point bending strength is not particularly limited, and the 3-point bending strength may be, for example, 1500MPa or less, and further 1000MPa or less. The 3-point bending strength of the zirconia sintered body can be measured according to JIS R1601: 2008.

The zirconia sintered body of the present invention is excellent in light transmittance despite containing a fluorescent agent. The transmittance of the zirconia sintered body of the present invention for light having a wavelength of 700nm at a thickness of 0.5mm is preferably 40% or more, more preferably 45% or more, and may be 46% or more, 48% or more, 50% or more, and further 52% or more. When the transmittance is within the above range, the required light transmittance at the cut end portion can be easily satisfied when the material is used as, for example, a dental prosthesis. The upper limit of the transmittance is not particularly limited, and the transmittance may be, for example, 60% or less, and further 57% or less. The transmittance of light having a wavelength of 700nm at a thickness of 0.5mm of the zirconia sintered body may be measured by using a spectrophotometer, and for example, a spectrophotometer (manufactured by hitachi ハイテクノロジーズ, "hitachi spectrophotometer U-3900H") may be used to transmit and scatter light generated from a light source to a sample and measure the light by using an integrating sphere. In this measurement, the transmittance is measured in a wavelength region of 300 to 750nm, and then the transmittance with respect to light having a wavelength of 700nm is determined. As a sample used for the measurement, a disk-shaped zirconia sintered body having a diameter of 15mm × a thickness of 0.5mm, which was mirror-polished on both sides, was used.

The main crystal phase of the zirconia sintered body of the present invention may be either tetragonal or cubic, and the main crystal phase is preferably cubic. In the zirconia sintered body of the present invention, 50% or more is preferably cubic, and more preferably 70% or more is cubic. The proportion of cubic crystals in the zirconia sintered body can be determined by analysis of the crystal phase. Specifically, the surface of the zirconia sintered body can be measured by X-Ray Diffraction (XRD) measurement on the surface of the zirconia sintered body, and the measurement can be obtained by the following formula.

f_c＝ 100 × I_c/(I_m＋I_t＋I_c)。

Here, f_cThe ratio (%) of cubic crystals in the zirconia sintered body is shown, I_mShowing a peak (based on a monoclinic (11-1) plane) in the vicinity of 28 degrees 2 thetaPeak) height, I_tThe height of a peak (peak based on the (111) plane of the tetragonal crystal) in the vicinity of 30 degrees 2 θ is shown, I_cThe height of a peak (peak based on the (111) plane of a cubic crystal) in the vicinity of 30 degrees 2 θ is shown. In the case where it is difficult to separate the peak of the (111) plane based on the tetragonal crystal from the peak of the (111) plane based on the cubic crystal, the ratio of the tetragonal crystal to the cubic crystal can be obtained by the rettfield method or the like, and the obtained ratio can be multiplied by the height (I) of the peak based on the mixed phase_t＋c) Thereby obtaining I_tAnd I_c。

The ratio of the monoclinic phase to the tetragonal phase and the cubic phase after the zirconia sintered body of the present invention is immersed in hot water at 180 ℃ for 5 hours is preferably 5% or less, more preferably 3% or less, and still more preferably 1% or less. When the ratio is within the above range, for example, when the prosthesis is used as a dental prosthesis, the volume can be prevented from changing over time and the prosthesis can be prevented from being broken. This ratio can be found as follows: the surface of the zirconia sintered body was mirror-finished, and the surface was immersed in hot water at 180 ℃ for 5 hours, and then the above-mentioned portion was measured by X-Ray Diffraction (XRD; X-Ray Diffraction), and the measurement was obtained by the following formula.

f_m＝ 100 × I_m/(I_t＋c)。

Here, f_mThe ratio (%) of monoclinic phase to tetragonal and cubic crystals after immersion in hot water at 180 ℃ for 5 hours in the zirconia sintered body is shown as I_mThe height of a peak (peak based on a (11-1) plane of a monoclinic crystal) in the vicinity of 28 degrees 2 θ is shown, I_t＋cThe height of a peak (peak based on a mixed phase of a tetragonal (111) plane and a cubic (111) plane) at around 30 degrees 2 θ is shown. Note that a peak near 2 θ of 30 degrees is separated into a peak based on the (111) plane of tetragonal and a peak based on the (111) plane of cubic, and appears, and it is difficult to specify I above_t＋cIn the case of (2), the height (I) of the peak of the (111) plane based on the tetragonal crystal can be determined_t) Height (I) from peak of (111) plane based on cubic crystal_c) The sum being defined as above_t＋c。

The method for producing the zirconia sintered body of the present invention is not particularly limited, and for example, the zirconia sintered body containing a fluorescent agent and containing 4.5 to 9.0 mol% of yttria can be produced by sintering a zirconia molded body at normal pressure. Further, the sintered body of zirconia containing a fluorescent agent and containing 4.5 to 9.0 mol% of yttria, which is obtained by calcining the above-described zirconia compact or the like, may be sintered at normal pressure. The present invention includes a zirconia molded body containing a fluorescent agent, the zirconia molded body containing 4.5 to 9.0 mol% of yttria, the zirconia molded body having a 3-point bending strength of 500MPa or more after being sintered at 1100 ℃ for 2 hours under normal pressure, and a crystal grain size of 180nm or less after being sintered at 1100 ℃ for 2 hours under normal pressure; and a calcined zirconia body containing a fluorescent agent, the calcined zirconia body containing 4.5 to 9.0 mol% of yttria, wherein the calcined zirconia body has a 3-point bending strength of 500MPa or more after being sintered at 1100 ℃ for 2 hours under normal pressure, and a crystal grain size of 180nm or less after being sintered at 1100 ℃ for 2 hours under normal pressure. The zirconia sintered body of the present invention excellent in both light transmittance and strength despite containing a fluorescent agent can be easily produced from such a zirconia formed body and a zirconia calcined body.

[ zirconia molded article ]

The zirconia molded body of the present invention contains a fluorescent agent and 4.5 to 9.0 mol% of yttria, and has a 3-point bending strength of 500MPa or more after sintering at 1100 ℃ for 2 hours under normal pressure and a crystal grain size of 180nm or less after sintering at 1100 ℃ for 2 hours under normal pressure. The zirconia molded body of the present invention may be formed of zirconia particles.

The fluorescent agent contained in the zirconia molded body of the present invention may be the same as the fluorescent agent contained in the zirconia sintered body to be obtained. The content of the fluorescent agent in the zirconia molded body can be appropriately adjusted depending on the content of the fluorescent agent in the zirconia sintered body to be obtained, and the like. The specific content of the fluorescent agent contained in the zirconia molded body is preferably 0.001 mass% or more, more preferably 0.005 mass% or more, and further preferably 0.01 mass% or more, and furthermore preferably 1 mass% or less, more preferably 0.5 mass% or less, and further preferably 0.1 mass% or less, in terms of oxide of the metal element contained in the fluorescent agent, with respect to the mass of the zirconia contained in the zirconia molded body.

When a colorant is contained in the zirconia sintered body, it is preferable that such a colorant is contained in the zirconia molded body. The content of the colorant in the zirconia compact can be appropriately adjusted depending on the content of the colorant in the zirconia sintered body to be obtained, and the like. The specific content of the colorant contained in the zirconia molded body is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, further preferably 0.01% by mass or more, and furthermore preferably 5% by mass or less, more preferably 1% by mass or less, further preferably 0.5% by mass or less, and may be 0.1% by mass or less, and further may be 0.05% by mass or less, in terms of oxide of the metal element contained in the colorant, relative to the mass of the zirconia contained in the zirconia molded body.

When the zirconia sintered body contains a light transmittance adjuster, it is preferable that the zirconia molded body contain such a light transmittance adjuster. The content of the light transmittance adjuster in the zirconia compact can be appropriately adjusted depending on the content of the light transmittance adjuster in the zirconia sintered body to be obtained, and the like. The specific content of the light transmittance adjuster contained in the zirconia molded body is preferably 0.1 mass% or less with respect to the mass of zirconia contained in the zirconia molded body.

The content of yttria in the zirconia compact of the present invention may be the same as the content of yttria in the zirconia sintered body obtained, and the specific content of yttria in the zirconia compact is 4.5 mol% or more, preferably 5.0 mol% or more, more preferably 5.5 mol% or more, and 9.0 mol% or less, preferably 8.0 mol% or less, more preferably 7.0 mol% or less. The content of yttria in the zirconia molded body is a ratio (mol%) of the number of moles of yttria to the total number of moles of zirconia and yttria.

The density of the zirconia compact is not particularly limited, and varies depending on the method for producing the zirconia compact, and the like, and is preferably 3.0g/cm from the viewpoint of obtaining a dense zirconia sintered body, and the like³Above, more preferably 3.2g/cm³The aboveMore preferably 3.4g/cm³The above. The upper limit of the density is not particularly limited, and may be set to, for example, 6.0g/cm³The concentration of the carbon black is set to 5.8g/cm³The following.

The shape of the zirconia compact is not particularly limited, and can be made into a desired shape according to the application, and is preferably a disk shape, a prism shape (a rectangular parallelepiped shape, or the like), or the like in consideration of handling properties or the like when a zirconia compact used as a polishing material for producing a dental material such as a dental prosthesis or the like is obtained. Note that, if a photo-forming method or the like is used for the production of a zirconia compact as described later, the zirconia compact can be given a shape corresponding to a desired shape in a zirconia sintered body to be finally obtained, and the present invention also includes a zirconia compact having such a desired shape. The zirconia molded body may have a single-layer structure or a multilayer structure. By providing a multilayer structure, the finally obtained zirconia sintered body can be made into a multilayer structure, and physical properties such as light transmittance can be locally changed.

The biaxial bending strength of the zirconia molded body is preferably in the range of 2 to 10MPa, more preferably in the range of 5 to 8MPa, from the viewpoint of handling properties and the like. The biaxial bending strength of the zirconia molded body can be measured according to JIS T6526: 2012.

The zirconia compact of the present invention has a crystal grain size of 180nm or less after being sintered at 1100 ℃ for 2 hours under normal pressure (after being made into a zirconia sintered body; it may be sintered under the above conditions after being calcined at 700 ℃ for 2 hours once under normal pressure). This makes it possible to easily produce the zirconia sintered body of the present invention having excellent light transmittance. The crystal grain size is preferably 140nm or less, more preferably 120nm or less, further preferably 115nm or less, and may be 110nm or less, from the viewpoint of obtaining a zirconia sintered body having more excellent light transmittance. The lower limit of the crystal grain size is not particularly limited, and the crystal grain size may be, for example, 50nm or more, and further 100nm or more. The method of measuring the crystal grain size is as described above for the crystal grain size in the zirconia sintered body.

The zirconia compact of the present invention has a 3-point bending strength of 500MPa or more after being sintered at 1100 ℃ for 2 hours under normal pressure (after being made into a zirconia sintered body; it may be sintered under the above conditions after being calcined at 700 ℃ for 2 hours once under normal pressure). This makes it possible to easily produce the zirconia sintered body of the present invention having excellent strength. The 3-point bending strength is preferably 600MPa or more, more preferably 650MPa or more, further preferably 700MPa or more, and particularly preferably 800MPa or more, from the viewpoint of obtaining a zirconia sintered body having more excellent strength. The upper limit of the 3-point bending strength is not particularly limited, and the 3-point bending strength may be, for example, 1500MPa or less, and further 1000MPa or less. The method of measuring the 3-point bending strength is as described above for the 3-point bending strength in the zirconia sintered body.

The transmittance of light having a wavelength of 700nm at a thickness of 0.5mm after the zirconia compact is sintered at 1100 ℃ for 2 hours under normal pressure (after the zirconia compact is produced; it may be sintered under the above conditions after the zirconia compact is calcined at 700 ℃ for 2 hours under normal pressure). This makes it possible to easily produce the zirconia sintered body of the present invention having excellent light transmittance. The transmittance is more preferably 45% or more, and may be 46% or more, 48% or more, 50% or more, and further 52% or more, from the viewpoint of obtaining a zirconia sintered body having more excellent light transmittance. The upper limit of the transmittance is not particularly limited, and the transmittance may be, for example, 60% or less, and further 57% or less. The transmittance was measured as described above for light having a wavelength of 700nm at a thickness of 0.5mm in the zirconia sintered body.

[ method for producing zirconia molded article ]

The method for producing the zirconia molded body of the present invention is not particularly limited, and is preferably produced by a method having a molding step of molding zirconia particles, and more preferably by a method having a molding step of molding zirconia particles in the presence of a fluorescent agent, since the zirconia sintered body of the present invention having excellent light transmittance and strength can be easily obtained.

The content of yttria in the zirconia particles used is preferably set to be the same as the content of yttria in the zirconia compact obtained, and further, the zirconia calcined body and the zirconia sintered body, and the specific content of yttria in the zirconia particles is preferably 4.5 mol% or more, more preferably 5.0 mol% or more, and further preferably 5.5 mol% or more, and further preferably 9.0 mol% or less, more preferably 8.0 mol% or less, and further preferably 7.0 mol% or less. The content of yttria in the zirconia particles is a ratio (mol%) of the number of moles of yttria to the total number of moles of zirconia and yttria.

The average primary particle diameter of the zirconia particles used is preferably 30nm or less. Thus, the zirconia compact of the present invention, and further the zirconia calcined body and the zirconia sintered body of the present invention can be easily obtained. From the viewpoint of ease of production of the zirconia compact of the present invention, further the zirconia calcined body of the present invention, and the zirconia sintered body, the average primary particle diameter of the zirconia particles is more preferably 20nm or less, further preferably 15nm or less, may be 10nm or less, and is preferably 1nm or more, more preferably 5nm or more. The average primary particle diameter of the zirconia particles can be determined as follows: for example, a Transmission Electron Microscope (TEM) is used to photograph zirconia particles (primary particles), and the particle diameter (maximum diameter) of each particle is measured for any 100 particles on the obtained image, and the average value of the particle diameters is determined.

In addition, from the viewpoint of easily obtaining the zirconia compact of the present invention, further the zirconia calcined body of the present invention, the zirconia sintered body of the present invention, and the like, the content of primary particles having a particle size of 50nm or more in the zirconia particles to be used is preferably 5% by mass or less, more preferably 3% by mass or less, and still more preferably 1% by mass or less. The content can be measured by a Zeta potential measuring instrument, for example.

The method for producing the zirconia particles is not particularly limited, and for example, a decomposition (ブレークダウン) process in which coarse particles are pulverized to be micronized, a build-up (ビルディングアップ) process in which synthesis is performed from atoms and/or ions by a nucleus formation/growth process, and the like can be used. Among them, in order to obtain high-purity fine zirconia particles, a construction process is preferable.

The decomposition process may be performed by pulverization using, for example, a ball mill, a bead mill, or the like. In this case, a finely-sized pulverization medium is preferably used, and a pulverization medium of, for example, 100 μm or less is preferably used. Further, it is preferable to perform classification after pulverization.

On the other hand, examples of the construction process include a gas phase thermal decomposition method in which an oxygen-containing acid salt of a metal ion having a high vapor pressure or an organic metal compound is thermally decomposed while being vaporized to deposit an oxide; a gas-phase reaction method in which a metal compound gas having a high vapor pressure and a reaction gas are synthesized by a gas-phase chemical reaction; an evaporative concentration method in which a raw material is vaporized by heating and the vapor is condensed into fine particles by quenching in an inert gas at a specific pressure; a melt method in which a melt is cooled and solidified in the form of small droplets to form powder; a solvent evaporation method in which a solvent is evaporated to increase the concentration in a liquid and the liquid is precipitated in a supersaturated state; and a precipitation method in which a solute concentration is brought into a supersaturated state by a reaction with a precipitant and hydrolysis, and a poorly soluble compound such as an oxide or a hydroxide is precipitated through a nucleus formation-growth process.

The precipitation process can be further subdivided into: a uniform precipitation method in which a precipitant is generated in a solution by a chemical reaction, thereby eliminating local unevenness in the concentration of the precipitant; a coprecipitation method in which a plurality of metal ions coexisting in a liquid are simultaneously precipitated by adding a precipitant; a hydrolysis method of obtaining an oxide or hydroxide from an alcohol solution of a metal salt solution, a metal alkoxide or the like by hydrolysis; a solvothermal synthesis method for obtaining an oxide or hydroxide from a fluid at high temperature and high pressure, and the solvothermal synthesis method can be further subdivided into: hydrothermal synthesis using water as a solvent; a supercritical synthesis method in which a supercritical fluid such as water or carbon dioxide is used as a solvent.

In any of the construction processes, in order to obtain finer zirconia particles, it is preferable to increase the precipitation rate. Further, the obtained zirconia particles are preferably classified.

As the zirconium source in the construction process, for example, nitrate, acetate, chloride, alkoxide, and the like can be used, and specifically, zirconyl chloride, zirconium acetate, zirconium nitrate, and the like can be used.

In order to set the content of yttria in the zirconia grains to the above range, yttria may be added in the production process of the zirconia grains, and, for example, yttria may be dissolved in the zirconia grains. As the yttrium source, for example, nitrate, acetate, chloride, alkoxide, and the like can be used, and specifically, yttrium chloride, yttrium acetate, yttrium nitrate, and the like can be used.

The zirconia particles may utilize an organic compound having an acidic group as needed; fatty acid amides such as saturated fatty acid amide, unsaturated fatty acid amide, saturated fatty acid bisamide, and unsaturated fatty acid bisamide; a known surface treatment agent such as a silane coupling agent (organosilicon compound), an organic titanium compound, an organic zirconium compound, an organic aluminum compound or other organic metal compound is subjected to surface treatment in advance. When the zirconia particles are surface-treated, when a powder containing the zirconia particles and the fluorescent agent is prepared using a slurry containing a liquid having a surface tension of 50mN/m or less at 25 ℃ in a dispersion medium as described later, the miscibility with the liquid can be adjusted, and when a zirconia molded body is produced by a method having a step of polymerizing a composition containing the zirconia particles, the fluorescent agent, and the polymerizable monomer as described later, the miscibility between the zirconia particles and the polymerizable monomer can be adjusted. Among the above surface treatment agents, organic compounds having an acidic group are preferable because they are excellent in miscibility with a liquid having a surface tension of 50mN/m or less at 25 ℃, and can improve the chemical bonding property between the zirconia particles and the polymerizable monomer to improve the strength of the zirconia molded body to be obtained.

Examples of the organic compound having an acidic group include organic compounds having an acidic group such as at least 1 phosphoric acid group, carboxylic acid group, pyrophosphoric acid group, thiophosphoric acid group, phosphonic acid group, or sulfonic acid group, and among these, organic compounds having a phosphoric acid group having at least 1 phosphoric acid group and organic compounds having a carboxylic acid group having at least 1 carboxylic acid group are preferable, and organic compounds having a phosphoric acid group are more preferable. The zirconia grains may be surface-treated with 1 kind of surface treatment agent, or may be surface-treated with 2 or more kinds of surface treatment agents. When the zirconia grains are surface-treated with 2 or more surface-treating agents, the surface-treated layer to be realized by this treatment may be a surface-treated layer of a mixture of 2 or more surface-treating agents, or may be a surface-treated layer having a multilayer structure in which a plurality of surface-treated layers are stacked.

Examples of the organic compound having a phosphoric acid group include 2-ethylhexyl acid phosphate, stearyl acid phosphate, 2- (meth) acryloyloxyethyl dihydrogen phosphate, 3- (meth) acryloyloxypropyl dihydrogen phosphate, 4- (meth) acryloyloxybutyl dihydrogen phosphate, 5- (meth) acryloyloxypentyl dihydrogen phosphate, 6- (meth) acryloyloxyhexyl dihydrogen phosphate, 7- (meth) acryloyloxyheptyl dihydrogen phosphate, 8- (meth) acryloyloxyoctyl dihydrogen phosphate, 9- (meth) acryloyloxynonyl dihydrogen phosphate, 10- (meth) acryloyloxydecyl dihydrogen phosphate, 11- (meth) acryloyloxyundecyl dihydrogen phosphate, 12- (meth) acryloyloxydodecyl dihydrogen phosphate, and mixtures thereof, 16- (meth) acryloyloxycetacyl phosphate, 20- (meth) acryloyloxyeicosyl phosphate, bis [2- (meth) acryloyloxyethyl ] hydrogen phosphate, bis [4- (meth) acryloyloxybutyl ] hydrogen phosphate, bis [6- (meth) acryloyloxyhexyl ] hydrogen phosphate, bis [8- (meth) acryloyloxyoctyl ] hydrogen phosphate, bis [9- (meth) acryloyloxynonyl ] hydrogen phosphate, bis [10- (meth) acryloyloxydecyl ] hydrogen phosphate, 1, 3-di (meth) acryloyloxypropyl phosphate, 2- (meth) acryloyloxyethylphenyl hydrogen phosphate, 2- (meth) acryloyloxyethyl-2-bromoethyl hydrogen phosphate, propylene oxide, bis [2- (meth) acryloyloxy- (1-hydroxymethyl) ethyl ] hydrogenphosphate, and acid halides, alkali metal salts, ammonium salts thereof and the like.

Examples of the organic compound having a carboxylic acid group include succinic acid, oxalic acid, octanoic acid, decanoic acid, stearic acid, polyacrylic acid, 4-methyloctanoic acid, neodecanoic acid, pivalic acid, 2-dimethylbutyric acid, 3-dimethylbutyric acid, 2-dimethylpentanoic acid, 2-diethylbutanoic acid, 3-diethylbutanoic acid, naphthenic acid, cyclohexanedicarboxylic acid, (meth) acrylic acid, N- (meth) acryloylglycine, N- (meth) acryloylaspartic acid, O- (meth) acryloyltyrosine, N- (meth) acryloylp-aminobenzoic acid, N- (meth) acryloylanthranilic acid, p-vinylbenzoic acid, 2- (meth) acryloyloxybenzoic acid, acrylic acid, 3- (meth) acryloyloxybenzoic acid, 4- (meth) acryloyloxybenzoic acid, N- (meth) acryloyl-5-aminosalicylic acid, N- (meth) acryloyl-4-aminosalicylic acid, 2- (meth) acryloyloxyethyl succinate, 2- (meth) acryloyloxyethyl phthalate, 2- (meth) acryloyloxyethyl hydrogen maleate, 2- (2- (2-methoxyethoxy) ethoxy) acetic acid (generically referred to as "MEEAA"), 2- (2-methoxyethoxy) acetic acid (generically referred to as "MEAA"), mono [2- (2-methoxyethoxy) ethyl ] succinate, mono [2- (2-methoxyethoxy) ethyl ] maleate, 4- (meth) acryloyloxybenzoic acid, N- (meth) acryloyl-5-aminosalicylic acid, N- (meth) acryloyl-4-aminosalicylic acid, hydrogen succinate, 2, Glutaric acid mono [2- (2-methoxyethoxy) ethyl ] ester, malonic acid, glutaric acid, 6- (meth) acryloyloxyhexane-1, 1-dicarboxylic acid, 9- (meth) acryloyloxynonane-1, 1-dicarboxylic acid, 10- (meth) acryloyloxydecane-1, 1-dicarboxylic acid, 11- (meth) acryloyloxyundecane-1, 1-dicarboxylic acid, 12- (meth) acryloyloxydodecane-1, 1-dicarboxylic acid, 13- (meth) acryloyloxytridecane-1, 1-dicarboxylic acid, trimellitic acid 4- (meth) acryloyloxyethyl ester, trimellitic acid 4- (meth) acryloyloxybutyl ester, trimellitic acid 4- (meth) acryloyloxyhexyl ester, glutaric acid, maleic acid, Trimellitic acid 4- (meth) acryloyloxydecyl ester, succinic acid 2- (meth) acryloyloxyethyl-3 '- (meth) acryloyloxy-2' - (3, 4-dicarboxybenzoyloxy) propyl ester, and acid anhydrides, acid halides, alkali metal salts, ammonium salts thereof, and the like.

As the organic compound having at least 1 acidic group other than the above groups, such as a pyrophosphate group, a phosphorothioate group, a phosphonate group, and a sulfonate group, for example, an organic compound described in international publication No. 2012/042911 can be used.

Examples of the saturated fatty acid amide include palmitic acid amide, stearic acid amide, and behenic acid amide. Examples of the unsaturated fatty acid amide include oleamide and erucamide. Examples of the saturated fatty acid bisamide include ethylene dipalmitate amide, ethylene bisstearamide, and hexamethylene bisstearamide. Examples of the unsaturated fatty acid bisamide include ethylene bisoleic acid amide, hexamethylene bisoleic acid amide, and N, N' -dioleyl sebacic acid amide.

Examples of the silane coupling agent (organosilicon compound) include R¹ _nSiX_4-nThe compound represented by the formula (wherein R is¹Is a substituted or unsubstituted hydrocarbon group having 1 to 12 carbon atoms, X is an alkoxy group having 1 to 4 carbon atoms, a hydroxyl group, a halogen atom or a hydrogen atom, and n is an integer of 0 to 3, wherein a plurality of R's are present¹And X may be the same or different from each other).

Specific examples of the silane coupling agent (organosilicon compound) include methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β -methoxyethoxy) silane, 3,3, 3-trifluoropropyltrimethoxysilane, methyl-3, 3, 3-trifluoropropyldimethoxysilane, β - (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, γ -glycidoxypropyltrimethoxysilane, γ -glycidoxypropylmethyldiethoxysilane, γ -glycidoxypropyltriethoxysilane, γ -methacryloxypropylmethyldimethoxysilane, γ -methacryloxypropylmethyldiethoxysilane, N- (β -aminoethyl) γ -aminopropylmethyldimethoxysilane, N- (β -aminoethyl) γ -aminopropyltrimethoxysilane, N- (β -aminoethyl) γ -aminopropyltriethoxysilane, γ -aminopropyltrimethoxysilane, N- (gamma-aminopropyl) γ -aminopropyltrimethoxysilane, N- (β -aminopropyl) γ -aminopropyltrimethoxysilane, N- (gamma-aminopropyltrimethoxysilane, N- (3-methacryloxypropyl) γ -methacryloxypropyltrimethoxysilane, N- (3-methacryloxypropyl) trimethoxysilane, N- (3-methacryloxypropyl) γ -methacryloxypropyl) trimethoxysilane, N- (3-methacryloxypropyl) trimethoxysilane, 2-methacryloxypropyl) trimethoxysilane, the number of methacryloxypropyl-methacryloxy silane, the two of the above-methacryloxypropyl trimethoxysilane, the above-methacryloxy silane, the above-methacryloxypropyl trimethoxysilane, the specification includes, the number of two, the number of the two, the specification, the number of the above, the number of carbon atoms.

Among these, a silane coupling agent having a functional group is preferable, and ω - (meth) acryloyloxyalkyltrimethoxysilane [ (the number of carbon atoms between a (meth) acryloyloxy group and a silicon atom: 3 to 12], ω - (meth) acryloyloxyalkyltriethoxysilane [ (number of carbon atoms between meth) acryloyloxy group and silicon atom: 3-12 ], vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, and gamma-glycidoxypropyltrimethoxysilane.

Examples of the organic titanium compound include tetramethyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, and tetra (2-ethylhexyl) titanate.

Examples of the organozirconium compound include zirconium isopropoxide, zirconium n-butoxide, zirconium acetylacetonate, and zirconium acetate.

Examples of the organoaluminum compound include aluminum acetylacetonate and an aluminum organic acid salt chelate compound.

The specific method of surface treatment is not particularly limited, and a known method can be used, and for example, a method of adding the surface treatment agent by spraying while vigorously stirring zirconia particles; a method of dispersing or dissolving the zirconia particles and the surface treatment agent in an appropriate solvent, and then removing the solvent. The solvent may be a dispersion medium containing a liquid having a surface tension of 50mN/m or less at 25 ℃ as described later. After the zirconia particles and the surface treatment agent are dispersed or dissolved, the mixture may be subjected to a reflux or a high-temperature high-pressure treatment (e.g., autoclave treatment).

The type of the molding step in the production of the zirconia molded body by the method having the molding step of molding the zirconia particles is not particularly limited, and the molding step preferably includes any one of the following steps, from the viewpoint that the zirconia molded body of the present invention, further the zirconia calcined body of the present invention, the zirconia sintered body, and the like can be easily obtained:

(i) a step of slip casting a slurry containing zirconia particles and a fluorescent agent;

(ii) a step of gel-casting a slurry containing zirconia particles and a fluorescent agent;

(iii) a step of press-molding a powder containing zirconia particles and a fluorescent agent;

(iv) a step of molding a composition containing zirconia particles, a fluorescent agent, and a resin; and

(v) and a step of polymerizing a composition containing the zirconia particles, the fluorescent agent, and the polymerizable monomer.

Seed slurry containing zirconia particles and phosphor

The method of producing the slurry containing zirconia particles and the fluorescent agent is not particularly limited, and can be obtained by, for example, mixing the slurry containing zirconia particles with the fluorescent agent. The slurry containing zirconia particles to be used may be a slurry obtained by the above-described crushing process and building process, or may be a commercially available slurry.

When the slurry containing zirconia particles and the fluorescent agent in a liquid state is prepared by mixing the slurry containing zirconia particles and the fluorescent agent, it is preferable to prevent the mixing of coarse particles and the like, and to easily obtain the zirconia molded body and the zirconia calcined body of the present invention, and further, to easily obtain the zirconia sintered body of the present invention having excellent light transmittance and strength in spite of containing the fluorescent agent. As the fluorescent agent in a liquid state, for example, a solution, a dispersion, or the like of the above fluorescent agent can be used, and a solution of the fluorescent agent is preferable. The type of the solution is not particularly limited, and examples thereof include aqueous solutions. The aqueous solution may be a dilute nitric acid solution, a dilute hydrochloric acid solution, or the like, and may be appropriately selected depending on the kind of the fluorescent agent used, or the like.

In the case where the zirconia compact, and further the zirconia calcined body and the zirconia sintered body, contain a colorant and/or a light transmittance adjuster, such a colorant and/or a light transmittance adjuster may be contained in a slurry containing zirconia particles and a fluorescent agent. In this case, the colorant and/or the light transmittance adjuster are preferably mixed with the slurry containing the zirconia particles in a liquid state such as a solution or a dispersion.

Zizania seed containing zirconium oxide particles and phosphor powder

The method for producing the powder containing the zirconia particles and the fluorescent agent is not particularly limited, and the powder can be produced by dry-blending the powdered zirconia particles and the powdered fluorescent agent (here, in the case where the zirconia molded body, further the zirconia calcined body and the zirconia sintered body contain the colorant and/or the light transmittance adjusting agent, the colorant and/or the light transmittance adjusting agent may be further dry-blended), and from the viewpoint that a zirconia sintered body having more uniformity and excellent physical properties can be obtained, it is preferable to obtain the slurry containing the zirconia particles and the fluorescent agent by drying. The slurry for drying here may further contain a colorant and/or a light transmittance modifier.

The drying method is not particularly limited, and spray drying (spray drying), supercritical drying, freeze drying, hot air drying, reduced pressure drying, and the like can be used, for example. Among these, from the viewpoint that aggregation of particles can be suppressed during drying to obtain a more dense zirconia sintered body, and the like, any of spray drying, supercritical drying, and freeze drying is preferable, any of spray drying and supercritical drying is more preferable, and spray drying is further preferable.

The slurry containing the zirconia particles and the fluorescent agent to be dried may be a slurry in which the dispersion medium is water, and is preferably a slurry of a dispersion medium other than water, such as an organic solvent, since aggregation of particles can be suppressed at the time of drying and a more dense zirconia sintered body can be obtained.

Examples of the organic solvent include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, 2-methoxyethanol, 2-ethoxyethanol, 2- (2-ethoxyethoxy) ethanol, diethylene glycol monobutyl ether, and glycerol; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran, diethyl ether, diisopropyl ether, 1, 4-dioxane, and dimethoxyethane (including modified ethers such as propylene glycol monomethyl ether acetate (generally referred to as "PGMEA") (preferably ether-modified ethers and/or ester-modified ethers, and more preferably ether-modified alkylene glycols and/or ester-modified alkylene glycols)); ethyl acetate, butyl acetate and like esters; hydrocarbons such as hexane and toluene; halogenated hydrocarbons such as chloroform and carbon tetrachloride. These organic solvents may be used alone in 1 kind, or may be used in combination in 2 or more kinds. Among these, in view of both safety to living bodies and ease of removal, the organic solvent is preferably a water-soluble organic solvent, and more specifically, ethanol, 2-propanol, t-butanol, 2-ethoxyethanol, 2- (2-ethoxyethoxy) ethanol, propylene glycol monomethyl ether acetate, acetone, and tetrahydrofuran are more preferable.

In particular, when spray drying is employed, if a liquid having a surface tension of 50mN/m or less at 25 ℃ is contained in a dispersion medium of a slurry containing zirconia particles and a fluorescent agent to be dried, aggregation of particles can be suppressed at the time of drying, and a more dense zirconia sintered body can be obtained, which is preferable. From this viewpoint, the surface tension of the liquid is preferably 40mN/m or less, more preferably 30mN/m or less.

The surface tension at 25 ℃ can be determined, for example, by the values described in Handbook of Chemistry and Physics, and for liquids not described therein, the values described in International publication No. 2014/126034 can be used. The liquid that is not described in any of them can be obtained by a known measurement method, and can be measured by, for example, a hanging wheel method, a Wilhelmy method, or the like. The surface tension at 25 ℃ is preferably measured using an automatic surface tension meter "CBVP-Z" manufactured by Kshistra scientific Co., Ltd., or "SIGMA 702" manufactured by KSVINSTRUMENTS LTD Co., Ltd.

As the liquid, an organic solvent having the surface tension can be used. As the organic solvent, a solvent having the surface tension among the above-mentioned organic solvents can be used, and at least 1 kind selected from methanol, ethanol, 2-methoxyethanol, 1, 4-dioxane, 2-ethoxyethanol, and 2- (2-ethoxyethoxy) ethanol is preferable, and at least 1 kind selected from methanol, ethanol, 2-ethoxyethanol, and 2- (2-ethoxyethoxy) ethanol is more preferable, since aggregation of particles can be suppressed at the time of drying and a denser zirconia sintered body can be obtained.

The content of the liquid in the dispersion medium is preferably 50% by mass or more, more preferably 80% by mass or more, further preferably 95% by mass or more, and particularly preferably 99% by mass or more, from the viewpoint that aggregation of particles can be suppressed during drying to obtain a more dense zirconia sintered body.

A slurry of a dispersion medium other than water can be obtained by replacing the dispersion medium with a slurry in which the dispersion medium is water. The method of replacing the dispersion medium is not particularly limited, and for example, a method of adding a dispersion medium (such as an organic solvent) other than water to a slurry in which the dispersion medium is water and then distilling off the water can be employed. In the distillation of water, a part or all of the dispersion medium other than water may be distilled off. The addition of the dispersion medium other than water and the distillation-off of water may be repeated several times. In addition, a method of adding a dispersion medium other than water to a slurry in which the dispersion medium is water and then precipitating the dispersoid may be employed. Further, in the slurry in which the dispersion medium is water, the dispersion medium may be replaced with a specific organic solvent, and then replaced with another organic solvent.

The fluorescent agent may be added after replacing the dispersion medium, but is preferably added before replacing the dispersion medium, because a more uniform zirconia sintered body having excellent physical properties can be obtained. Similarly, when the colorant and/or the light transmittance adjuster are contained in the slurry, they may be added after the dispersion medium is replaced, but it is preferable to add them before the dispersion medium is replaced, because a more uniform zirconia sintered body having excellent physical properties can be obtained, and the like.

The slurry containing the zirconia particles and the fluorescent agent to be dried may be subjected to a dispersion treatment using heat or pressure, such as a reflow treatment or a hydrothermal treatment. Further, the slurry containing zirconia particles and the fluorescent agent for drying may be subjected to mechanical dispersion treatment using a roll mill, a colloid mill, a high-pressure jet disperser, an ultrasonic disperser, a vibration mill, a planetary mill, a bead mill, or the like. The above treatments may be used in only 1 kind, or may be used in 2 or more kinds.

The slurry containing zirconia particles and a fluorescent agent for drying may further contain 1 or 2 or more of other components such as a binder, a plasticizer, a dispersant, an emulsifier, a defoaming agent, a pH adjuster, a lubricant, and the like. By containing such other components (particularly, a binder, a dispersant, an antifoaming agent, and the like), aggregation of particles can be suppressed during drying, and a more dense zirconia sintered body can be obtained in some cases.

Examples of the binder include polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, acrylic binders, wax binders, polyvinyl butyral, polymethyl methacrylate, and ethyl cellulose.

Examples of the plasticizer include polyethylene glycol, glycerin, propylene glycol, dibutyl phthalate, and the like.

Examples of the dispersant include ammonium polycarboxylate (such as triammonium citrate), ammonium polyacrylate, acrylic copolymer resin, acrylic ester copolymer, polyacrylic acid, bentonite, carboxymethyl cellulose, anionic surfactant (such as polyoxyethylene alkyl ether phosphate (such as polyoxyethylene lauryl ether phosphate)), nonionic surfactant, glyceryl oleate, amine surfactant, and oligosaccharide alcohol.

Examples of the emulsifier include alkyl ethers, phenyl ethers, sorbitan derivatives, and ammonium salts.

Examples of the defoaming agent include alcohols, polyethers, polyethylene glycols, silicones, and waxes.

Examples of the pH adjuster include ammonia, ammonium salts (including ammonium hydroxide such as tetramethylammonium hydroxide), alkali metal salts, and alkaline earth metal salts.

Examples of the lubricant include polyoxyethylene alkylated ethers and waxes.

The moisture content in the slurry containing zirconia particles and the fluorescent agent to be dried is preferably 3 mass% or less, more preferably 1 mass% or less, and even more preferably 0.1 mass% or less, from the viewpoint that aggregation of particles with each other can be suppressed at the time of drying and a denser zirconia sintered body can be obtained. The moisture content can be measured using a Karl Fischer moisture meter.

The drying conditions in the above-mentioned drying methods are not particularly limited, and known drying conditions can be appropriately employed. When an organic solvent is used as the dispersion medium, the drying is preferably performed in the presence of a nonflammable gas, and more preferably in the presence of nitrogen gas, in order to reduce the risk of explosion during the drying.

The supercritical fluid used in the supercritical drying is not particularly limited, and for example, water, carbon dioxide, or the like can be used, but carbon dioxide is preferred because aggregation of particles can be suppressed to obtain a more dense zirconia sintered body.

Compositions containing zirconium oxide particles, phosphors and resins

The method for producing the composition containing the zirconia particles, the fluorescent agent, and the resin is not particularly limited, and can be obtained by, for example, mixing the above-described powder containing the zirconia particles and the fluorescent agent with the resin.

Compositions containing zirconia particles, phosphors and polymerizable monomers

The method for producing the composition containing the zirconia particles, the fluorescent agent, and the polymerizable monomer is not particularly limited, and can be obtained by, for example, mixing the powder containing the zirconia particles and the fluorescent agent described above with the polymerizable monomer.

(i) Slip casting

When the zirconia molded body is produced by a method including a step of slip casting a slurry containing zirconia particles and a fluorescent agent, a specific method of the slip casting is not particularly limited, and for example, a method of flowing the slurry containing zirconia particles and a fluorescent agent into a mold and then drying the slurry can be employed.

The content of the dispersion medium in the slurry containing zirconia particles and the fluorescent agent used is preferably 80% by mass or less, more preferably 50% by mass or less, and still more preferably 20% by mass or less, from the viewpoints that the slurry easily flows into the mold, that drying can be prevented from taking a lot of time, and that the number of times the mold is used can be increased.

The inflow of the slurry into the mold may be performed under normal pressure, and is preferably performed under pressurized conditions from the viewpoint of production efficiency. The type of the mold used for slip casting is not particularly limited, and a porous mold made of, for example, gypsum, resin, ceramics, or the like can be used. From the viewpoint of durability, a porous mold made of resin or ceramics is excellent.

The slurry containing zirconia grains and a fluorescent agent used for slip casting may further contain at least 1 of the colorant and the light transmittance adjuster as described above, or may further contain 1 or 2 or more of other components such as the binder, plasticizer, dispersant, emulsifier, defoamer, pH adjuster, lubricant, and the like as described above.

(ii) Gel casting

When the zirconia molded body is produced by a method including a step of gel-casting a slurry containing zirconia particles and a fluorescent agent, a specific method of gel-casting is not particularly limited, and for example, a method of gelling a slurry containing zirconia particles and a fluorescent agent in a mold to obtain a shaped wet body and then drying the shaped wet body can be employed.

The content of the dispersion medium in the slurry containing zirconia particles and the fluorescent agent used is preferably 80% by mass or less, more preferably 50% by mass or less, and still more preferably 20% by mass or less, from the viewpoints that it is possible to prevent a large amount of time from being consumed for drying, and also to suppress the occurrence of cracks and the like during drying.

The gelling may be performed by, for example, adding a gelling agent, or by adding a polymerizable monomer and then polymerizing the monomer. The kind of the mold to be used is not particularly limited, and a porous mold made of, for example, gypsum, resin, ceramics, etc.; a non-porous mold made of metal, resin, or the like, and the like.

The type of the gelling agent is not limited, and for example, a water-soluble gelling agent can be used, and specifically, agarose, gelatin, or the like can be preferably used. The gelling agent may be used alone in 1 kind, or may be used in combination of 2 or more kinds. From the viewpoint of suppressing the occurrence of cracks during sintering, the amount of the gelling agent to be used is preferably 10% by mass or less, more preferably 5% by mass or less, and still more preferably 1% by mass or less, based on the mass of the slurry after the gelling agent is blended.

Further, the type of the polymerizable monomer is not particularly limited, and examples thereof include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, propylene glycol mono (meth) acrylate, glycerol mono (meth) acrylate, erythritol mono (meth) acrylate, N-methylol (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N- (dihydroxyethyl) (meth) acrylamide, and the like. The polymerizable monomer may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

From the viewpoint of suppressing the occurrence of cracks during firing, the amount of the polymerizable monomer to be used is preferably 10% by mass or less, more preferably 5% by mass or less, and still more preferably 1% by mass or less, based on the mass of the slurry after the polymerizable monomer is blended.

When gelation is caused by polymerization of the polymerizable monomer, the polymerization is preferably performed using a polymerization initiator. The kind of the polymerization initiator is not particularly limited, and a photopolymerization initiator is particularly preferable. The photopolymerization initiator can be appropriately selected from photopolymerization initiators used in general industrial fields and used, and among them, photopolymerization initiators used for dental applications are preferable.

Specific examples of the photopolymerization initiator include (bis) acylphosphine oxides (containing salts), thioxanthones (containing salts such as quaternary ammonium salts), ketals, α -diketones, coumarins, anthraquinones, benzoin alkyl ether compounds, α -aminoketone compounds, and the like, and 1 kind of the photopolymerization initiator may be used alone or 2 or more kinds of the photopolymerization initiator may be used in combination.

Among the above (bis) acylphosphines, as acylphosphines, examples thereof include 2,4, 6-trimethylbenzoyldiphenylphosphine oxide (generically referred to as "TPO"), 2, 6-dimethoxybenzoyldiphenylphosphine oxide, 2, 6-dichlorobenzoyldiphenylphosphine oxide, 2,4, 6-trimethylbenzoylmethoxyphenylphosphine oxide, 2,4, 6-trimethylbenzoylethoxyphenylphosphine oxide, 2,3,5, 6-tetramethylbenzoyldiphenylphosphine oxide, benzoylbis (2, 6-dimethylphenyl) phosphonate, the sodium salt of 2,4, 6-trimethylbenzoylphenylphosphine oxide, the potassium salt of 2,4, 6-trimethylbenzoyldiphenylphosphine oxide, the ammonium salt of 2,4, 6-trimethylbenzoyldiphenylphosphine oxide, and the like.

Among the above (bis) acylphosphine oxides, examples of bisacylphosphine oxides include bis (2, 6-dichlorobenzoyl) phenylphosphine oxide, bis (2, 6-dichlorobenzoyl) -2, 5-dimethylphenylphosphine oxide, bis (2, 6-dichlorobenzoyl) -4-propylphenylphosphine oxide, bis (2, 6-dichlorobenzoyl) -1-naphthylphosphine oxide, bis (2, 6-dimethoxybenzoyl) phenylphosphine oxide, bis (2, 6-dimethoxybenzoyl) -2,4, 4-trimethylpentylphosphine oxide, bis (2, 6-dimethoxybenzoyl) -2, 5-dimethylphenylphosphine oxide, bis (2,4, 6-trimethylbenzoyl) phenylphosphine oxide, bis (2, 6-dichlorobenzoyl) phenylphosphine oxide, bis (2, 6-dichlorophenyl) phenylphosphine oxide, Bis (2,3, 6-trimethylbenzoyl) -2,4, 4-trimethylpentylphosphine oxide, and the like. Further, compounds described in Japanese patent laid-open No. 2000-159621 and the like may be used.

Among these (bis) acylphosphine oxides, sodium salts of 2,4, 6-trimethylbenzoyldiphenylphosphine oxide, 2,4, 6-trimethylbenzoylmethoxyphenylphosphine oxide, bis (2,4, 6-trimethylbenzoyl) phenylphosphine oxide, and 2,4, 6-trimethylbenzoylphenylphosphine oxide are preferable.

Examples of the α -diketones include butanedione, benzil, camphorquinone, 2, 3-pentanedione, 2, 3-octanedione, 9, 10-phenanthrenequinone, 4' -oxybenzol, and acenaphthenequinone.

The slurry containing zirconia grains and a fluorescent agent used for gel casting may further contain at least one of the colorant and the light transmittance adjuster as described above, and may further contain 1 or 2 or more of the other components such as the binder, the plasticizer, the dispersant, the emulsifier, the defoaming agent, the pH adjuster, and the lubricant as described above, similarly to the slurry used for slip casting.

The drying method for drying the shaped wet body is not particularly limited, and examples thereof include natural drying, hot air drying, vacuum drying, dielectric heating drying, induction heating drying, constant temperature and humidity drying, and the like. These may be used in 1 kind alone or in 2 or more kinds. Among these, natural drying, dielectric heating drying, induction heating drying, and constant temperature and humidity drying are preferable because cracks and the like can be suppressed during drying.

(iii) Press forming

When the zirconia compact is produced by a method including a step of press-molding a powder containing zirconia particles and a fluorescent agent, a specific method of press-molding is not particularly limited, and the press-molding can be performed by using a known press-molding machine. Specific examples of the press forming include uniaxial pressing. In order to increase the density of the zirconia molded body obtained, it is preferable to further perform Cold Isostatic Pressing (CIP) treatment after uniaxial pressing.

The powder containing zirconia grains and a fluorescent agent used for press molding may further contain at least one of the coloring agent and the light transmittance adjusting agent as described above, or may further contain 1 or 2 or more of the other components such as the binder, plasticizer, dispersant, emulsifier, defoaming agent, pH adjuster, and lubricant as described above. These components may be blended at the time of preparing a powder.

(iv) Forming of resin-containing composition

When the zirconia molded body is produced by a method having a step of molding a composition containing zirconia particles, a fluorescent agent, and a resin, a specific method for molding the composition is not particularly limited, and for example, injection molding, cast molding, extrusion molding, or the like can be employed. Further, a method of shaping the composition by a hot melt method (FDM), a lamination shaping method (3D printing or the like) such as an ink jet method, a powder/binder lamination method or the like may be used. Among these molding methods, injection molding and cast molding are preferable, and injection molding is more preferable.

The type of the resin is not particularly limited, and a resin that functions as a binder can be preferably used. Specific examples of the resin include paraffin wax, polyvinyl alcohol, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, polystyrene, atactic polypropylene, methacrylic resin, and fatty acid such as stearic acid. These resins may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

The composition containing the zirconia particles, the fluorescent agent, and the resin may further contain at least one of the colorant and the light transmittance adjuster as described above, or may further contain 1 or 2 or more of other components such as the plasticizer, the dispersant, the emulsifier, the defoaming agent, the pH adjuster, and the lubricant as described above.

(v) Polymerization of composition containing polymerizable monomer

By polymerizing a composition containing zirconia particles, a fluorescent agent, and a polymerizable monomer, the polymerizable monomer in the composition can be polymerized to cure the composition. When the zirconia molded body is produced by the method having the polymerization step, the specific method is not particularly limited, and for example, (a) a method of polymerizing a composition containing zirconia particles, a fluorescent agent, and a polymerizable monomer in a mold; (b) a Stereolithography (SLA) method using a composition comprising zirconia particles, a fluorescent agent, and a polymerizable monomer, and the like. Among these, the stereolithography method (b) is preferable. According to the stereolithography method, a shape corresponding to a desired shape of a finally obtained zirconia sintered body can be provided when a zirconia molded body is produced. Therefore, the stereolithography method may be suitable particularly when the zirconia sintered body of the present invention is used as a dental material such as a dental prosthesis.

The polymerizable monomer in the composition containing the zirconia particles, the fluorescent agent, and the polymerizable monomer is not particularly limited in kind, and may be any of monofunctional polymerizable monomers such as monofunctional (meth) acrylate and monofunctional (meth) acrylamide, and polyfunctional polymerizable monomers such as bifunctional aromatic compounds, bifunctional aliphatic compounds, and trifunctional or higher compounds. The polymerizable monomer may be used alone in 1 kind, or may be used in combination in 2 or more kinds. Among these, in particular, when a stereolithography method is used, it is preferable to use a polyfunctional polymerizable monomer.

Examples of the monofunctional (meth) acrylate include (meth) acrylates having a hydroxyl group such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, propylene glycol mono (meth) acrylate, glycerol mono (meth) acrylate, erythritol mono (meth) acrylate, etc.; alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, isobutyl (meth) acrylate, n-hexyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, and stearyl (meth) acrylate; alicyclic (meth) acrylates such as cyclohexyl (meth) acrylate and isobornyl (meth) acrylate; aromatic group-containing (meth) acrylates such as benzyl (meth) acrylate and phenyl (meth) acrylate; and (meth) acrylates having a functional group such as 2, 3-dibromopropyl (meth) acrylate, 3- (meth) acryloyloxypropyltrimethoxysilane, and 11- (meth) acryloyloxyundecyltrimethoxysilane.

Examples of monofunctional (meth) acrylamide include (meth) acrylamide, N- (meth) acryloylmorpholine, N-dimethyl (meth) acrylamide, N-diethyl (meth) acrylamide, N-di-N-propyl (meth) acrylamide, N-di-N-butyl (meth) acrylamide, N-di-N-hexyl (meth) acrylamide, N-di-N-octyl (meth) acrylamide, N-di-2-ethylhexyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N-di (hydroxyethyl) (meth) acrylamide, and the like.

Among these monofunctional polymerizable monomers, (meth) acrylamide is preferable, and N- (meth) acryloylmorpholine, N-dimethyl (meth) acrylamide, and N, N-diethyl (meth) acrylamide are more preferable, from the viewpoint of excellent polymerizability.

Examples of the bifunctional aromatic compound include 2, 2-Bis ((meth) acryloyloxyphenyl) propane, 2-Bis [4- (3-acryloyloxy-2-hydroxypropoxy) phenyl ] propane, 2-Bis [4- (3-methacryloyloxy-2-hydroxypropoxy) phenyl ] propane (commonly known as "Bis-GMA"), 2-Bis (4- (meth) acryloyloxyethoxyphenyl) propane, 2-Bis (4- (meth) acryloyloxypolyethoxyphenyl) propane, 2-Bis (4- (meth) acryloyloxydiethoxyphenyl) propane, 2-Bis (4- (meth) acryloyloxytetraethoxyphenyl) propane, and, 2, 2-bis (4- (meth) acryloyloxypentaethoxyphenyl) propane, 2-bis (4- (meth) acryloyloxydipropylphenyl) propane, 2- (4- (meth) acryloyloxydiethoxyphenyl) -2- (4- (meth) acryloyloxyethoxyphenyl) propane, 2- (4- (meth) acryloyloxydiethoxyphenyl) -2- (4- (meth) acryloyloxydiethoxyphenyl) propane, 2- (4- (meth) acryloyloxydipropoxyphenyl) -2- (4- (meth) acryloyloxytetraoxyphenyl) propane, 2-bis (4- (meth) acryloyloxypropylphenyl) propane, 2-bis (4- (meth) acryloyloxydropoxyphenyl) propane, 2-bis (4- (meth) acryloyloxydropoxypropoxyphenyl) propane, 2, 2-bis (4- (meth) acryloyloxyisopropoxyphenyl) propane, 1, 4-bis (2- (meth) acryloyloxyethyl) pyromellitate, and the like. Among these, 2-Bis [4- (3-methacryloyloxy-2-hydroxypropoxy) phenyl ] propane (commonly referred to as "Bis-GMA") and 2, 2-Bis (4- (meth) acryloyloxypolyethoxyphenyl) propane are preferable from the viewpoint of excellent polymerizability and strength of the obtained zirconia molded product. Among 2, 2-bis (4- (meth) acryloyloxypolyethoxyphenyl) propanes, 2-bis (4-methacryloyloxypolyethoxyphenyl) propane (a compound having an average addition mole number of ethoxy groups of 2.6 (generally referred to as "D-2.6E")) is preferable.

Examples of the bifunctional aliphatic compound include glycerol di (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1, 3-butylene glycol di (meth) acrylate, 1, 4-butylene glycol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, 2-ethyl-1, 6-hexanediol di (meth) acrylate, 1, 9-nonanediol di (meth) acrylate, 1, 10-decanediol di (meth) acrylate, 1, 2-bis (3-methacryloyloxy-2-hydroxypropoxy) ethane, and the like, 2,2, 4-trimethylhexamethylene bis (2-carbamoyloxyethyl) dimethacrylate (commonly referred to as "UDMA"), and the like. Among these, triethylene glycol dimethacrylate (generically referred to as "TEGDMA") and 2,2, 4-trimethylhexamethylene bis (2-carbamoyloxyethyl) dimethacrylate are preferable from the viewpoint of excellent polymerizability and strength of the obtained zirconia molded product.

Examples of the trifunctional or higher-functional compound include trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, trimethylolmethane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, N- (2,2, 4-trimethylhexamethylene) bis [2- (aminocarboxy) propane-1, 3-diol ] tetra (meth) acrylate, and 1, 7-diacryloyloxy-2, 2,6, 6-tetra (meth) acryloyloxymethyl-4-oxyheptane. Among these, N- (2,2, 4-trimethylhexamethylene) bis [2- (aminocarboxy) propane-1, 3-diol ] tetramethacrylate, 1, 7-diacryloyloxy-2, 2,6, 6-tetraacryloxymethyl-4-oxyheptane are preferable from the viewpoint of excellent polymerizability and strength of the obtained zirconia molded article.

In any of the above-mentioned methods (a) and (b), the polymerization of the composition is also preferably carried out using a polymerization initiator, and the composition preferably further contains a polymerization initiator. The kind of the polymerization initiator is not particularly limited, and a photopolymerization initiator is particularly preferable. The photopolymerization initiator can be suitably selected from photopolymerization initiators used in general industrial fields, and among them, photopolymerization initiators used in dental applications are preferable. Specific examples of the photopolymerization initiator are the same as those described above in the description of gel casting, and overlapping description is omitted here.

The composition containing the zirconia particles, the fluorescent agent, and the polymerizable monomer may further contain at least 1 of the coloring agent and the light transmittance adjuster as described above, or may further contain 1 or 2 or more of other components such as the plasticizer, the dispersing agent, the emulsifier, the defoaming agent, the pH adjuster, and the lubricant as described above.

When the zirconia molded body is produced by the stereolithography method using the composition containing the zirconia particles, the fluorescent agent, and the polymerizable monomer, the specific method of the stereolithography method is not particularly limited, and the stereolithography can be appropriately performed by a known method. The following methods may be employed, for example: and a method of obtaining a target zirconia molded body by sequentially forming layers having a desired shape by photopolymerization of a liquid composition using a photo-molding device with ultraviolet rays, laser light, or the like.

In the case of obtaining a zirconia molded body by the stereolithography method, the content of zirconia particles in the composition containing zirconia particles, a fluorescent agent, and a polymerizable monomer is preferably as large as possible, specifically, 20 mass% or more, more preferably 30 mass% or more, further preferably 40 mass% or more, and particularly preferably 50 mass% or more, from the viewpoint of subsequent sinterability and the like. On the other hand, in the stereolithography method, it is desirable that the viscosity of the composition is within a certain fixed range from the viewpoint of the principle of the lamination molding, and therefore, the content of the zirconia particles in the composition is preferably 90% by mass or less, more preferably 80% by mass or less, still more preferably 70% by mass or less, and particularly preferably 60% by mass or less. In the case of performing the controlled liquid level method of curing layers by irradiating light from the lower side of a container through the bottom surface of the container to cure the layers and sequentially forming zirconia molded bodies layer by layer, the viscosity adjustment of the composition is particularly important in some cases for raising the cured layer by one layer and smoothly flowing a composition for forming the next layer between the lower surface of the cured layer and the bottom surface of the container.

The specific viscosity of the above composition is preferably 20,000mPa, seeds or less, more preferably 10,000mPa, seeds or less, even more preferably 5,000mPa, seeds or less, and further preferably 100mPa, seeds or more at 25 ℃. Since this composition tends to increase in viscosity as the content of zirconia particles increases, it is preferable to appropriately adjust the balance between the content of zirconia particles and the viscosity in the composition in consideration of the balance between the speed at the time of the stereolithography and the accuracy of the zirconia molded body to be obtained, for example, in accordance with the performance of the stereolithography apparatus to be used. The viscosity can be measured using an E-type viscometer.

[ calcined zirconia ]

The zirconia calcined body of the present invention contains a fluorescent agent and contains 4.5 to 9.0 mol% of yttria, and has a 3-point bending strength of 500MPa or more after being sintered at 1100 ℃ for 2 hours under normal pressure and a crystal grain size of 180nm or less after being sintered at 1100 ℃ for 2 hours under normal pressure. The zirconia calcined body of the present invention can be a calcined body obtained by calcining a zirconia compact formed of zirconia particles.

The phosphor contained in the zirconia sintered body of the present invention may be the same as the phosphor contained in the zirconia sintered body to be obtained. The content of the fluorescent agent in the zirconia sintered body can be appropriately adjusted depending on the content of the fluorescent agent in the zirconia sintered body to be obtained, and the like. The specific content of the fluorescent agent contained in the zirconia calcined body is preferably 0.001 mass% or more, more preferably 0.005 mass% or more, further preferably 0.01 mass% or more, and furthermore preferably 1 mass% or less, more preferably 0.5 mass% or less, further preferably 0.1 mass% or less in terms of oxide of the metal element contained in the fluorescent agent, relative to the mass of the zirconia contained in the zirconia calcined body.

In the case where the zirconia sintered body contains a colorant, it is preferable to contain such a colorant in the zirconia calcined body. The content of the colorant in the zirconia sintered body can be appropriately adjusted depending on the content of the colorant in the zirconia sintered body to be obtained, and the like. The specific content of the colorant contained in the zirconia calcined body is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, further preferably 0.01% by mass or more, and furthermore preferably 5% by mass or less, more preferably 1% by mass or less, further preferably 0.5% by mass or less, and may be 0.1% by mass or less, and further may be 0.05% by mass or less, in terms of the oxide of the metal element contained in the colorant, relative to the mass of the zirconia contained in the zirconia calcined body.

When the zirconia sintered body contains a light transmittance adjuster, it is preferable that the zirconia sintered body contains such a light transmittance adjuster. The content of the light transmittance adjuster in the zirconia sintered body can be appropriately adjusted according to the content of the light transmittance adjuster in the zirconia sintered body to be obtained, and the like. The specific content of the light transmittance adjuster contained in the calcined zirconia is preferably 0.1 mass% or less with respect to the mass of zirconia contained in the calcined zirconia.

The content of yttria in the zirconia calcined body of the present invention may be the same as the content of yttria in the obtained zirconia sintered body, and the specific content of yttria in the zirconia calcined body is 4.5 mol% or more, preferably 5.0 mol% or more, more preferably 5.5 mol% or more, and 9.0 mol% or less, preferably 8.0 mol% or less, more preferably 7.0 mol% or less. The content of yttria in the calcined zirconia is a ratio (mol%) of the number of moles of yttria to the total number of moles of zirconia and yttria.

The density of the zirconia calcined body is not particularly limited, and is preferably 3.0 to 6.0g/m, depending on the method for producing the zirconia compact used for the production thereof, and the like³More preferably 3.2 to 5.8g/m³Within the range of (1).

The shape of the calcined zirconia is not particularly limited, and can be made into a desired shape according to the application, and is preferably disk-shaped, prism-shaped (rectangular parallelepiped-shaped, etc.) or the like in consideration of handling properties or the like when used as a polishing material for producing a dental material such as a dental prosthesis. As will be described later, the calcined zirconia may be cut (polished) to a desired shape according to the application before the calcined zirconia is formed into a sintered zirconia, and the present invention also includes a calcined zirconia having such a desired shape after cutting (polishing). The calcined zirconia may have a single-layer structure or a multi-layer structure. The zirconia sintered body finally obtained can be made into a multilayer structure by making the structure into a multilayer structure, and physical properties such as light transmittance can be locally changed.

The 3-point bending strength of the zirconia calcined body is preferably within a range of 10 to 70MPa, more preferably within a range of 20 to 60MPa, from the viewpoints that the shape of the work can be maintained during processing using a cutting machine, and cutting itself can be easily performed. The 3-point bending strength of the zirconia calcined body was measured using a universal testing machine for a test piece of 5mm × 40mm × 10mm under conditions of a span length of 30mm and a crosshead speed of 0.5 mm/min.

The zirconia calcined body of the present invention has a crystal grain size of 180nm or less after being sintered at 1100 ℃ for 2 hours under normal pressure (after being made into a zirconia sintered body). This makes it possible to easily produce the zirconia sintered body of the present invention having excellent light transmittance. The crystal grain size is preferably 140nm or less, more preferably 120nm or less, further preferably 115nm or less, and may be 110nm or less, from the viewpoint of obtaining a zirconia sintered body having more excellent light transmittance. The lower limit of the crystal grain size is not particularly limited, and the crystal grain size may be, for example, 50nm or more, and further 100nm or more. The method of measuring the crystal grain size is as described above for the crystal grain size in the zirconia sintered body.

The zirconia sintered body of the present invention has a 3-point bending strength of 500MPa or more after sintering at 1100 ℃ for 2 hours under normal pressure (after forming a zirconia sintered body). This makes it possible to easily produce the zirconia sintered body of the present invention having excellent strength. The 3-point bending strength is preferably 600MPa or more, more preferably 650MPa or more, further preferably 700MPa or more, and particularly preferably 800MPa or more, from the viewpoint of obtaining a zirconia sintered body having more excellent strength. The upper limit of the 3-point bending strength is not particularly limited, and the 3-point bending strength may be, for example, 1500MPa or less, and further 1000MPa or less. The method of measuring the 3-point bending strength is as described above for the 3-point bending strength in the zirconia sintered body.

The transmittance of light having a wavelength of 700nm at a thickness of 0.5mm after the zirconia sintered body is sintered at 1100 ℃ for 2 hours under normal pressure (after the zirconia sintered body is produced) is preferably 40% or more. This makes it possible to easily produce the zirconia sintered body of the present invention having excellent light transmittance. The transmittance is more preferably 45% or more, and may be 46% or more, 48% or more, 50% or more, and further 52% or more, from the viewpoint of obtaining a zirconia sintered body having more excellent light transmittance. The upper limit of the transmittance is not particularly limited, and the transmittance may be, for example, 60% or less, and further 57% or less. The transmittance was measured as described above for light having a wavelength of 700nm at a thickness of 0.5mm in the zirconia sintered body.

[ method for producing calcined zirconia ]

The calcined zirconia body of the present invention can be obtained by calcining the above-described zirconia compact. The calcination temperature is preferably 300 ℃ or more, more preferably 400 ℃ or more, and still more preferably 500 ℃ or more, and is preferably less than 900 ℃, more preferably 850 ℃ or less, and still more preferably 800 ℃ or less, from the viewpoint of easily obtaining the target calcined zirconia and the like. By setting the calcination temperature to the lower limit or more, the generation of organic matter residue can be effectively suppressed. Further, by setting the calcination temperature to the upper limit or lower, excessive sintering can be suppressed, and cutting (polishing) by a cutting machine can be suppressed.

The rate of temperature rise during the calcination is not particularly limited, but is preferably 0.1 ℃/min or more, more preferably 0.2 ℃/min or more, and still more preferably 0.5 ℃/min or more, and is preferably 50 ℃/min or less, more preferably 30 ℃/min or less, and still more preferably 20 ℃/min or less. When the temperature increase rate is not less than the lower limit, productivity is improved. Further, by setting the temperature increase rate to the upper limit or less, the difference in volume between the inside and the outside of the zirconia compact and the zirconia calcined body can be suppressed, and when the zirconia compact contains an organic substance, rapid decomposition of the organic substance can be suppressed, and cracking or destruction can be suppressed.

The calcination time when the zirconia compact is calcined is not particularly limited, and is preferably 0.5 hours or more, more preferably 1 hour or more, further preferably 2 hours or more, and is preferably 10 hours or less, more preferably 8 hours or less, further preferably 6 hours or less, from the viewpoint of obtaining a target zirconia compact efficiently and stably with good productivity.

Calcination may be performed using a calciner. The type of the calcining furnace is not particularly limited, and for example, an electric furnace, a degreasing furnace, and the like generally used in the industry can be used.

The zirconia sintered body can be formed into a desired shape according to the use by cutting (grinding) before being formed into a zirconia sintered body. In particular, the zirconia sintered body of the present invention is excellent in both light transmittance and strength although it contains a fluorescent agent, and therefore, is particularly suitable as a dental material such as a dental prosthesis, and in order to obtain a zirconia sintered body used for such an application, the zirconia sintered body may be cut (ground) to form a shape corresponding thereto. The method of cutting (polishing) is not particularly limited, and can be performed using, for example, a known polishing apparatus.

[ method for producing zirconia sintered body ]

As described above, the zirconia sintered body of the present invention can be produced by sintering a zirconia molded body containing a fluorescent agent and containing 4.5 to 9.0 mol% of yttria at normal pressure, and can also be produced by sintering a zirconia calcined body containing a fluorescent agent and containing 4.5 to 9.0 mol% of yttria at normal pressure.

In both the case of sintering the zirconia compact and the case of sintering the zirconia calcined body, the sintering temperature is preferably 900 ℃ or higher, more preferably 1000 ℃ or higher, and even more preferably 1050 ℃ or higher, and further preferably 1200 ℃ or lower, more preferably 1150 ℃ or lower, and even more preferably 1120 ℃ or lower, from the viewpoint of easily obtaining the intended zirconia sintered body and the like. When the sintering temperature is not lower than the lower limit, sintering can be sufficiently performed, and a dense sintered body can be easily obtained. Further, by setting the sintering temperature to the above upper limit or less, a zirconia sintered body having a crystal grain diameter within the range of the present invention can be easily obtained, and deactivation of the fluorescent agent can be suppressed.

In both the case of sintering the zirconia compact and the case of sintering the zirconia calcined body, the sintering time is not particularly limited, and is preferably 5 minutes or more, more preferably 15 minutes or more, further preferably 30 minutes or more, and further preferably 6 hours or less, more preferably 4 hours or less, and further preferably 2 hours or less, from the viewpoint of being able to obtain the intended zirconia sintered body efficiently and stably with good productivity.

Sintering may be performed using a sintering furnace. The type of the sintering furnace is not particularly limited, and for example, an electric furnace, a degreasing furnace, and the like generally used in the industry can be used. In particular, when used for dental materials, a dental porcelain oven having a low sintering temperature may be used in addition to a conventional dental zirconia sintering oven.

The zirconia sintered body of the present invention can be easily produced without subjecting it to Hot Isostatic Pressing (HIP), but the transparency and strength can be further improved by subjecting it to the Hot Isostatic Pressing (HIP) after the sintering at normal pressure.

[ use of zirconia sintered body ]

The zirconia sintered body of the present invention is not particularly limited in use, and is excellent in both light transmittance and strength even though it contains a fluorescent agent, and therefore is particularly suitable as a dental material such as a dental prosthesis, and is particularly useful not only as a dental prosthesis used in a dental neck but also as a dental prosthesis used in a molar occlusal surface and a front tooth incisal end portion (front incisal end portion). The zirconia sintered body of the present invention is particularly preferably used as a dental prosthesis used for a front tooth cutting end portion.