JPH0833701A - Zirconia medical material and manufacture therefor - Google Patents

Abstract

PURPOSE:To provide a zirconia-based medical material which has high mechanical properties and is excellent in heat stability. CONSTITUTION:A zirconia-based medical material is composed mainly of ZrO2 and contains at least one kind selected from Yb2O3, Er2-O3, Ho2O3, Y2O3, and Dy2O3, a boron compound, and further Al2O3, and SiO2. Further, at least one kind selected from La2O3, Pr2O11/2, Nd2O3, Sm2O3 and Gd2O3 may be used jointly. A raw material obtained from the above composition by an oxide mixing method is calcined at 500-1200 deg.C and then sintered at 1500-1700 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rare earth metal oxide-stabilized zirconia-based medical material containing a boron compound having high mechanical properties and excellent thermal stability, and a method for producing the same.

[0002]

_2. Description of the Related Art In recent years, zirconia (ZrO ₂ ) based sintered bodies have been applied in various fields by applying the characteristics of materials.
It is used as a member material. Examples thereof include ceramic scissors to which the toughness is applied, adiabatic engine parts utilizing the properties of heat insulation and thermal expansion, oxygen sensors and fuel cells to which oxygen ion conductivity is applied.
Furthermore, the unique physical properties of zirconia ceramics correspond to the recent demands for a highly welfare society, and doctors use scalpels, scissors, tweezers, orthodontic brackets, crowns, roots, for the purpose of treatment and diagnosis. It has attracted attention as a medical material suitable for joints and bone fixing materials.

[0003] As medical materials conventionally used,
There are many metal products, and various materials such as carbon steel, stainless steel, special alloys are used, but cleaning with hot water or steam,
When sterilized and disinfected, or when it is attached to a human body, there are problems such as rust due to the influence of moisture, elution of metal ions, or poor aesthetics depending on the attachment site. Although polymer materials have been studied and used in view of such rust, elution of metal ions, and aesthetics, polymer materials have a problem in terms of mechanical properties.

Therefore, the application of a zirconia-based sintered body having higher mechanical properties without the fear of rusting or elution of metal ions due to the influence of water to medical instruments is disclosed in Japanese Patent Publication No. 61-60697. Have been proposed. This zirconia-based sintered body is supposed to contain at least 50 mol% of zirconia having a tetragonal crystal structure and 10 mol% or less of zirconia having a cubic crystal structure. In the description of the examples of the publication, changes in characteristics of zirconia blades at 120 ° C. and 1.2 atm in a steam sterilizer are described in relation to use as a medical instrument. Furthermore,
JP-A-62-235255, JP-B-3-2902
In Japanese Patent Laid-Open No. 1, a zirconia-based sintered body is described as various applications and applications as medical devices and medical materials.
However, these publications do not sufficiently describe the application of the zirconia-based sintered body to medical materials.

[0005]

The conventional zirconia-based sintered body has a drawback that if it is left at about 100 to 300 ° C. for a long time, the strength is remarkably reduced. Such low thermal stability is due to the fact that, of the crystal phases of the zirconia-based sintered body, the tetragonal crystal, which is a metastable phase at room temperature, transforms into the monoclinic crystal of the stable phase, and the volume expansion accompanying the phase transition is calcined. This is due to the generation of microcracks in the conglomerate. In particular, this phase transition is
It occurs at a temperature lower than the above temperature in an environment of water or water vapor, and its speed is also very high, so it is high temperature (100
This is a problem when washing or sterilizing using water as a solvent at a temperature of up to 300 ° C.

[0006] Further, regarding the influence of eating habits on health in recent years, orthodontic treatment has been attracting attention. With orthodontic treatment, not only the alignment of teeth is improved but also the masticatory function is improved. At this time, the bracket used by adhering to the tooth surface is required to be able to withstand the thermal conditions derived from sterilization before use or foods and drinks in the oral cavity during use. A zirconia-based sintered body that sufficiently satisfies the required properties has not been provided.

The present invention has been made in view of the above-mentioned conventional circumstances, and is excellent in mechanical properties and has good thermal stability in the temperature range as described above, and a method for producing the same. The purpose is to provide.

[0008]

The zirconia-based medical material according to claim 1 contains ZrO ₂ as a main component, and Yb ₂ O ₃ , E.
R ₂ O ₃ , Ho ₂ O ₃ , Y ₂ O _3, and one or more rare earth metals selected from the group consisting of Dy ₂ O ₃ (R
It is characterized by containing the oxide (R1-O) of 1) and a boron compound.

The zirconia-based medical material according to claim 2 is the zirconia-based medical material according to claim 1, wherein Zr
Oxide of rare earth metal (R1) with respect to O ₂ (R1-O)
The molar ratio of (R1-O / ZrO ₂₎ is 1.5 / 98.5
˜5 / 95.

The zirconia-based medical material according to claim 3 is Z
rO ₂ as a main component, Yb ₂ O ₃ , Er ₂ O ₃ , Ho ₂
Oxide of one or more rare earth metal (R1) selected from the group consisting of O ₃ , Y ₂ O ₃ and Dy ₂ O ₃ (R1
And _{-O), La 2 O 3,} Pr 2 O 11/3, Nd 2 O 3, S
one or oxides of two or more rare earth metals (R2) selected from the group consisting of m ₂ O ₃ and _{Gd 2 O 3 (R2-O} )
And a boron compound.

The zirconia-based medical material according to claim 4 is the zirconia-based medical material according to claim 3, wherein the oxide (R1-O) of the rare earth metal (R1) and the oxide of the rare earth metal (R2) are included. (R2-O) molar ratio (R1-O /
R2-O) is 30/70 or more and less than 100/0.

A zirconia-based medical material according to claim 5 is the zirconia-based medical material according to claim 3 or 4, wherein an oxide (R1) of a rare earth metal (R1) with respect to ZrO _{2 is} used.
1-O) and rare earth metal (oxide of R2) (R2-O) and the total molar ratio of ((R1-O + R2- O) / ZrO 2)
Is 1.5 / 98.5-5 / 95.

A zirconia-based medical material according to claim 6 is the zirconia-based medical material according to any one of claims 1 to 5, wherein the boron compound is boron oxide, boron nitride, boron carbide or zirconium boride. , One or more boron compounds selected from the group consisting of borides of rare earth metals (R1) and borides of rare earth metals (R2).

The zirconia-based medical material according to claim 7 is the zirconia-based medical material according to any one of claims 1 to 6, wherein the content of the boron compound is 0. It is characterized by being 05 to 8 mol%.

The zirconia-based medical material according to claim 8 is the zirconia-based medical material according to any one of claims 1 to 7, further comprising Al ₂ O ₃ and / or SiO 2.
It is characterized by including ₂ .

A zirconia-based medical material according to claim 9 is the zirconia-based medical material according to claim 8, wherein the boron compound is boron oxide, boron nitride, boron carbide, zirconium boride, or a rare earth metal (R1). It is characterized by being one or more kinds of boron compounds selected from the group consisting of borides, borides of rare earth metals (R2), aluminum borides and silicon borides.

The zirconia-based medical material according to claim 10 comprises:
In the zirconia-based medical material according to claim 8 or 9, the content of the boron compound is 0.05 to 8% mol% in terms of boron (B), and the content of Al ₂ O ₃ is 0.1 to 0.1%.
5 mol%, the content of SiO ₂ is 0.05 to 1.5 mol%
Is characterized in that.

The zirconia-based medical material according to claim 11 comprises:
The zirconia-based medical material according to any one of claims 1 to 10, wherein the average particle diameter is 3 µm or less, the bulk density is 5.8 g / cm ³ or more, and the crystal particles are mainly tetragonal phase or tetragonal phase. Consisting of a mixed phase of crystals and cubic crystals, 1
It is characterized in that deterioration of the material does not easily occur even when used for a long time in the air or water and steam at a temperature of 00 to 300 ° C.

The zirconia-based medical material according to claim 12 is
The zirconia-based medical material according to any one of claims 1 to 11, wherein a scalpel, scissors, tweezers, orthodontic bracket, crown, root, joint used for the purpose of treatment or diagnosis in the medical field. It is characterized by being used as a bone fixing material.

A method for producing the zirconia-based medical material according to claim 13 is a method for producing the zirconia-based medical material according to any one of claims 1 to 12, which is a chemical synthesis method (neutralization method). Precipitation method, hydrolysis method, alkoxide method, etc.)
Alternatively, after being calcined at a temperature of 500 to 1200 ° C., obtained by a method of mixing oxide powder, 1300 to 17
It is characterized by being sintered at 00 ° C.

The present invention will be described in detail below.

In the zirconia-based medical material of the present invention, the rare earth metal used as a stabilizer is Yb ₂ O ₃ ,
_{Er 2 O 3, Ho 2 O} 3, Y 2 O 3 and Dy ₂ O 1 or two or more rare earth metals ₃ selected from the group consisting of (hereinafter referred to as "R1".) Oxide (hereinafter "R1 -O "is abbreviated.). Also, with this R1-O, La ₂
O ₃ , Pr ₂ O _11/3 , Nd ₂ O ₃ , Sm ₂ O ₃ and Gd ₂
An oxide of one or more rare earth metals (hereinafter abbreviated as “R2”) selected from the group consisting of O ₃ (hereinafter referred to as “R2”).
-O "is abbreviated. ) May be used together. In addition, Sc ₂ O
₃ , Eu ₂ O ₃ , Tb ₂ O ₃ , Tm ₂ O _7/2 and Lu ₂
O ₃ can also be used as a stabilizer, but these are very expensive, and when used as a zirconia product, they pose a problem in terms of cost competitiveness in the market.

Of these rare earth metal oxides, R1-
O has the effect of stabilizing ZrO ₂ and makes it possible to obtain a good zirconia-based medical material having high mechanical properties. On the other hand, when R2-O is used alone as a stabilizer, a zirconia-based medical material stabilized with R1-O is unlikely to be a good material having high mechanical properties. However, by the present inventors, R
By mixing 1-O and R2-O at a constant ratio to form a stabilizer, it has properties equivalent to those of conventionally known zirconia-based medical materials stabilized by R1-O alone. It has been found that a zirconia-based medical material can be obtained. This constant ratio is a ratio defined in the present invention, and is a molar ratio of R1-O and R2-O (R1-O /
R2-O) is 30/70 or more and less than 100/0.
But the molar ratio is the amount of R2-O is often less than 30/70 the greater the impact of the R2-O, it is difficult to stabilize the ZrO _2. From this, R1-O
And R2-O molar ratio R1-O / R2-O is 30/70
If the content is out of the above range, it may not be possible to obtain a zirconia-based medical material having excellent properties aimed at by the present invention. Therefore, R1-O / R2-O is 30/7.
Set to 0 or more.

In the present invention, the molar ratio of the total rare earth metal oxide to ZrO ₂ , that is, R 1 -O / ZrO 2 when only R 1 -O is used as the rare earth metal oxide.
_2, when used in combination with R1-O and R2-O as the rare earth metal oxides (R1-O + R2-O ) / ZrO 2 ( hereinafter, collectively the R1-O, R2-O as "R-O" Then, the molar ratio of the rare earth metal oxide and ZrO ₂ is set to “RO / Zr
Abbreviated as "O ₂ ". ) Is preferably in the range of 1.5 / 98.5 to 5/95, and particularly preferably in the range of 2/98 to 4/96. R
The molar ratio of -O / ZrO ₂ is less than 1.5 / 98.5, hardly sintered, stable tetragonal to obtain zirconia medical material is not generated, zirconia medical consisting mainly of tetragonal There is no material available. Further, if it exceeds 5/95, a zirconia-based medical material having sufficient mechanical properties cannot be obtained.

The zirconia-based medical material of the present invention contains a compound consisting of boron in its raw material composition. This is for the following reason. That is, as a result of observing the bending strength and the surface structure of the sample which was subjected to the underwater test at 200 ° C. for 250 hours, the zirconia sintered body containing no boron compound showed a large decrease in strength, and many fine particles were observed on the surface of the sample. A crack was observed (see FIG. 1 (a)). On the other hand, in the zirconia sintered body to which the boron compound was added, the above-mentioned deteriorated layer was hardly observed, but it was very thin (see FIG. 1 (b)). The strength of the sample before the test was different depending on whether or not the boron compound was added, and the strength of the added one was clearly recognized. From these, it was found that the boron compound is an additive that can further increase the strength of the zirconia-based medical material and improve the thermal stability. That is, in the zirconia-based medical material of the present invention,
If the boron compound is not contained, a zirconia-based medical material cannot be obtained. Even if the boron compound is contained, if the content is less than 0.05 mol% (B conversion), the effect of the addition of the boron compound is can not see. Further, when the boron compound is added in an amount of more than 8 mol% (calculated as B), the strength tends to be rather lowered. From this, the addition amount of the boron compound is 0.05 to 8 mol% in terms of B,
It is preferably 0.05 to 5 mol%.

In the zirconia-based medical material of the present invention, it is preferable to further add Al ₂ O ₃ and / or SiO _{2. The} addition makes the sample easy to sinter and can be fired at a low temperature. In comparison with the sample to which the boron compound, Al ₂ O ₃ and SiO ₂ were added in the optimum amount, the sample to which only the boron compound was added had a firing temperature of about 50 to obtain the same density and mechanical strength. ~ 1
It is necessary to raise the temperature by 00 ° C. (No. 4 and No. 1 of Example 1)
6 relationship). ). Therefore, Al ₂ O ₃ and / or SiO
It is possible to reduce the amount of the boron compound added by adding ₂ .

Further, Al ₂ O ₃ is effective in improving the mechanical strength, especially hardness characteristics of the zirconia-based medical material. Further, by uniformly dispersing it in zirconia, the sinterability is improved. However, the effect of adding Al ₂ O ₃ does not appear when the content is less than 0.1 mol%. On the contrary, the addition of more than 5 mol% causes a decrease in density and mechanical strength. Therefore, when Al ₂ O ₃ is added,
The amount added is 0.1 to 5 mol%, preferably 0.3 to 2
Mol%.

On the other hand, SiO ₂ is an additive capable of improving the sinterability of the zirconia-based medical material. Therefore, by adding SiO ₂ , it becomes possible to sinter the sample at a low temperature, and the firing cost can be reduced.
Further, effects such as suppressing grain growth can be obtained. But,
If the amount of SiO ₂ is less than 0.05 mol%, SiO ₂
No effect of addition is observed. Further, when SiO ₂ is added in an amount of more than 1.5 mol%, grain growth is promoted, resulting in deterioration of mechanical strength and thermal stability. Therefore, when SiO ₂ is added, the addition amount is 0.05 to
It is set to 1.5 mol%, preferably 0.1 to 0.5 mol%.

These additives are added components (Al, S
Similar effects can be obtained by adding in the form of nitride, carbide, hydroxide or the like in addition to the oxide of i). As for the boron compound, an oxide of boron (B ₂ O
_In addition to ₃ ), nitride (BN), carbide (B ₄ C), or Zr as the main component, a rare earth metal as a stabilizer,
Alternatively, a boride (Z, Z), which is an additive component such as Al or Si
rB ₂ , YB ₈ , AlB ₂ , SiB _4, etc.).

In order to produce a zirconia-based medical material according to the method of the present invention, first, an oxide mixing method or a chemical synthesis method such as a neutralization coprecipitation method, a hydrolysis method or an alkoxide method is used to produce ZrO ₂ A raw material of the above-mentioned composition containing R—O and a boron compound, more preferably Al ₂ O ₃ and / or SiO ₂ is prepared. Next, the obtained raw material powder is added to 5
It is calcined within a temperature range of 00 to 1200 ° C., and the calcined powder is crushed and then molded. The molding method is not particularly limited, and a die method, a CIP method, an injection method, an extrusion method, a casting method and the like can be adopted. The obtained molded body is 1300 to 17
Sintering is performed within a temperature range of 00 ° C, preferably 1400 to 1600 ° C.

In the method of the present invention, calcination is performed to make the mixed raw material as uniform as possible and to promote the sintering in the firing process by causing a part of ZrO ₂ to undergo phase transition. And is an important requirement in the manufacturing method of the present invention. Even under the calcination conditions here, the lower limit value is 500.
C is the lowest temperature at which part of the monoclinic ZrO ₂ crystal can be transformed into a tetragonal phase by calcination. Generally, Z
The transition of rO ₂ from monoclinic to tetragonal is said to be around 1170 ° C. However, by adding a stabilizer to ZrO ₂ , the temperature shifts to a low temperature, and for example Y ₂ O ₃ is stabilized. When used as an agent, a phase transition is observed at a temperature of about 800 ° C. This temperature varies depending on the type or amount of stabilizer. On the other hand, the upper limit of the calcination temperature is 120
0 ° C. is the maximum temperature at which the agglomerated powder found in the raw material after calcination can be sufficiently crushed in the crushing step. It remains and becomes a major breaking point, leading to a decrease in strength of the zirconia-based medical material. Therefore, the calcination temperature is 500-
The temperature is 1200 ° C., preferably 800 to 1200 ° C.

The sintering temperature for main firing is 1300 ° C.
If it is less than 1, the densification does not proceed, while if it exceeds 1700 ° C., a high-strength sintered body cannot be obtained due to abnormal grain growth of crystal grains.

The zirconia-based medical material of the present invention has the above-mentioned composition and manufacturing method, has an average particle size of 3 μm or less, preferably 2 μm or less, and a bulk density of 5.8 g / cm ³ or more, It is preferably 5.9 g / cm ³ or more, and the crystal grains mainly consist of a tetragonal phase or a mixed phase of tetragonal and cubic, and are in the air or water and water vapor at a temperature of 100 to 300 ° C. When used for a long time, the material is unlikely to deteriorate. A zirconia-based medical material having an average particle size of more than 3 μm cannot obtain good properties in terms of thermal stability and the like. Therefore, when used at a temperature of 100 to 300 ° C. in the air or in water and steam for a long time, the material is deteriorated. The bulk density is 5.8 g /
Similarly, if it is less than ³ cm ^{3, the} effect of improving the thermal stability cannot be obtained.

The monoclinic crystal, tetragonal crystal, and
The content of the cubic crystal was obtained by grinding the material surface with a # 600 diamond grindstone, finishing it to a mirror surface with 1 to 5 μm diamond grains, and using the following formula from the intensity ratio of the surface by X-ray diffraction. .

[0035]

[Equation 1]

In order to measure the average particle size, first, the surface of the above-mentioned mirror-finished sintered body is subjected to etching treatment with hydrofluoric acid, and the number of particles is determined by electron microscopy.
The diameter d of a circle that is equal to the area S including zero or more
Is calculated by the formula d = (4S / π) ^1/2 . And
d is determined for three or more visual fields of the same sample, and the average value is defined as the average particle size. The number n of particles is the sum of the number of particles completely contained in the fixed area S and 1/2 of the number of particles cut by the boundary line of the fixed area (for the measuring method, Japanese Patent Publication No. 61-21184). reference).

In the present invention, in particular, the zirconia-based medical material having higher mechanical properties can be produced by producing the zirconia-based medical material by the pressure sintering treatment. For example, a strength of 100 kg produced by firing after CIP molding in the examples described later.
For f / mm ^{2 and} above, 140k by HIP treatment
A high-strength sintered body of gf / mm ² or more can be obtained.

[0038]

The medical material of the present invention is an RO-stabilized zirconia-based sintered body containing a boron compound, and it is preferable that the composition has the composition defined in the present invention.
In addition to satisfying the bulk density and the crystal constitution phase, the mechanical properties of the zirconia-based sintered body are as high as those of the commercially available zirconia-based sintered bodies, and the thermal stability which is the main object of the present invention is extremely high. It is an excellent zirconia-based sintered body.

Particularly, in the zirconia-based medical material of the present invention, by further adding Al ₂ O ₃ and / or SiO ₂ , low temperature calcination becomes possible and the addition amount of the boron compound can be reduced. There is an advantage. Further, in particular, Al ₂ O ₃ has an effect of improving the mechanical strength of the zirconia-based medical material, in particular, hardness characteristics, and further, by uniformly dispersing in zirconia, an effect of improving sinterability. Is obtained.

On the other hand, SiO ₂ is an additive that can improve the sinterability of zirconia-based medical materials, and S
By adding iO ₂ , the sample can be sintered at a low temperature, the firing cost can be reduced, and the effect of suppressing grain growth can be obtained.

The zirconia-based medical material of the present invention is effective as a material used for scalpels, scissors, tweezers, orthodontic brackets, crowns, roots, joints, bone fixing materials, etc., but especially in recent years. As an orthodontic material that has been attracting attention as an effect of eating habits on health or as an element such as beauty, the mechanical properties of the zirconia ceramics according to the present invention, thermal stability, or aesthetics close to the color tone of teeth, etc. It is a suitable material from the viewpoint of.

[0042]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

Example 1 Zirconium oxide (Z
rO _2), R1-O and R2-O rare earth metal oxides (R-O), aluminum oxide (Al ₂ O _3), silicon dioxide (SiO _2), were weighed boron oxide (B ₂ O ₃₎ After using ion-exchanged water as a solvent and kneading with a ZrO ₂ boulder in a rubber lined ball mill,
It was dried.

Then, calcination is carried out at the temperatures shown in Tables 5 to 8 (however, in Tables 5 to 8, those having a calcination temperature of 0 ° C. are not calcined), and the obtained calcined powder is subjected to the above-mentioned treatment. The mixture was crushed by the same ball mill as at the time of kneading, 3% by weight of an acrylic copolymer resin was added, and spray granulation was performed. 1000 kgf / c of the obtained granulated powder
CIP molding was performed at a pressure of m ² and main firing was performed at the temperatures shown in Tables 5 to 8.

The "average crystal grain size", "bulk density", main "crystal phase" of the obtained zirconia-based sintered body, the bending strength test method for fine ceramics (JIS R1601)
"3-point bending strength", "Vickers hardness" (JIS R1610), "fracture toughness value" (JIS R1607) obtained by IF method, and "thermal stability" of the sintered body were measured according to Are shown in Tables 5-8.

The "thermal stability" of the sintered body was determined by placing the sintered body in an autoclave and subjecting it to an aging test for 250 hours in hot water at 200 ° C., and observing the degree of deterioration of the sintered body. I made a decision. As can be seen from the cross section of the sintered body shown in FIG. 1, the one with poor thermal stability (x) has a transition phase 2 layer (tetragonal → cubic) on the surface of Sample 1A as shown in FIG. 1 (a). The transformed phase) is thick (50 μm or more) and has many microcracks 3
Was recognized. On the other hand, in the case of good thermal stability (◯), as shown in FIG. 1B, the layer of the transition phase 2 on the surface of the sample 1B was thin (10 μm or less), and no microcracks were observed. Furthermore, the ones with the best thermal stability (⊚) are shown in each table.

In Tables 1 to 4, for example, No. 25
“Y ₂ O ₃ + Yb ₂ O ₃ ” indicates that Y ₂ O ₃ and Yb ₂ O ₃ are used in combination, and the molar ratio of 1 + 2/97 is Y ₂ O 3.
₃ is 1 mol and Yb ₂ O ₃ is 2 mol. Others are the same. In Tables 5 to 8, M
Indicates a monoclinic crystal, T indicates a tetragonal crystal, and C indicates a cubic crystal.

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

[Table 3]

[0051]

[Table 4]

[0052]

[Table 5]

[0053]

[Table 6]

[0054]

[Table 7]

[0055]

[Table 8]

From the obtained results, the following is clear.

The zirconia-based medical material of the present invention contains a rare earth metal oxide R--O and a boron compound, and further contains A
l ₂ O ₃ and SiO ₂ were added, and the boron compound was added to 0.0
5 to 8 mol% (converted to B), Al ₂ O _{3 in the} range of 0.1 to 5 mol%, and SiO ₂ in the range of 0.05 to 1.5 mol%, having high mechanical properties and heat It has excellent stability. On the other hand, without a boron compound, a zirconia-based sintered body having excellent mechanical properties and thermal stability cannot be obtained.

Further, the molar ratio of the stabilizer R--O and ZrO ₂ is within the preferred range of the present invention, and the above-mentioned three kinds of additives according to the present invention are each within the numerical range of the present invention. Even if the composition contained is used, sufficient mechanical properties cannot be obtained if the calcination is carried out under a condition outside the range of 500 to 1200 ° C. Similarly,
Even under the main-baking conditions, if the conditions are outside the numerical limit range of the present invention, as a result, a zirconia-based medical material having sufficient mechanical properties cannot be obtained.

Example 2 Of the composition shown in Example 1, zirconium oxide (ZrO ₂ ), Y ₂ was added so as to have the composition of Nos. 4, 25 and 51.
O ₃ , Yb ₂ O ₃ , Gd ₂ O ₃ , aluminum oxide (A
l ₂ O ₃ ), silicon dioxide (SiO ₂ ), and boron oxide (B ₂ O ₃ ) were weighed and calcined at the temperatures shown in Table 9, and the calcined powder obtained was crushed with a ball mill. Then, it was used as a starting material powder. On the other hand, in order to prepare an injection molding compound, a general resin was added, the mixture was heated and kneaded by a heating kneader, and further pelletized for stable supply into the injection molding machine.

Then, the compound was put into an injection molding machine which holds a mold for designing a predetermined shape of an intended orthodontic bracket, and molded. The molded product was decomposed and dissipated in the compound at a temperature of about 350 ° C.
It was sintered at the main firing temperature shown in.

The surface of the manufactured orthodontic bracket was polished, and the "Vickers hardness" (JIS R1610) and "fracture toughness value" (JIS R1607) were measured by the same method as in Example 1. In addition, "heat stability" is 250 in hot water of 120 ℃ in an autoclave.
A time aging test was performed and evaluated. The results are shown in Table 9.

From the obtained results, the following is clear. As in Example 1, the zirconia-based medical material of the present invention shows excellent Vickers hardness and fracture toughness values as zirconia ceramics as compared with commercially available materials as the properties of the sintered body, and is thermally stable. In terms of sex, it was confirmed that the surface of the bracket did not deteriorate at all, and it was suggested that there would be no problem if sterilization conditions or usual oral use conditions were taken into consideration.

[0063]

[Table 9]

[0064]

As described in detail above, according to the zirconia-based medical material and the method for producing the same of the present invention, ZrO ₂ is the main component, and the rare earth metal oxide (RO) in the predetermined range and the predetermined range are contained. Contains a boron compound, and if necessary, Al ₂
A zirconia-based medical material containing an additive composed of O ₃ and SiO ₂ and having excellent mechanical properties and thermal stability is provided.

The zirconia-based medical material of the present invention as described above can be easily and efficiently manufactured reliably by the method of the present invention.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a cross section of a sintered body according to a thermal stability evaluation test in Example 1, where FIG. 1 (a) shows poor thermal stability and FIG. 1 (b) shows thermal stability. Show good things.

[Explanation of symbols]

 1A, 1B Sample 2 Transition phase 3 Microcrack

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Ryo Nakayama 957-5 Ouchi, Kurashiki City, Okayama Prefecture (72) Inventor Masahiro Yoshida 452-149, Nakakayama, Hidaka City, Saitama Prefecture Inventor Hiroaki Tanji Kanagawa 6-29-6-905 Nakanoshima, Tama-ku, Kawasaki

Claims (13)

[Claims] 1. Yb ₂ O ₃ , E containing ZrO ₂ as a main component
R ₂ O ₃ , Ho ₂ O ₃ , Y ₂ O _3, and one or more rare earth metals selected from the group consisting of Dy ₂ O ₃ (R
A zirconia-based medical material comprising the oxide (R1-O) of 1) and a boron compound. 2. A zirconia medical material according to claim 1, oxides of rare earth metals (R1) relative to ZrO ₂ (R1-O) molar ratio of (R1-O / ZrO ₂₎ is,
A zirconia-based medical material characterized by being 1.5 / 98.5 to 5/95. 3. Yb ₂ O ₃ , E containing ZrO ₂ as a main component
R ₂ O ₃ , Ho ₂ O ₃ , Y ₂ O _3, and one or more rare earth metals selected from the group consisting of Dy ₂ O ₃ (R
1) oxides of _{(R1-O), La 2} O 3, Pr 2 O
_11/3 , one or more rare earth metals (R2) selected from the group consisting of Nd ₂ O ₃ , Sm ₂ O ₃ and Gd ₂ O _3.
A zirconia-based medical material comprising the oxide (R2-O) of 1) and a boron compound. 4. The zirconia-based medical material according to claim 3, wherein an oxide (R1-O) of a rare earth metal (R1) is used.
And a rare earth metal (R2) oxide (R2-O) molar ratio (R1-O / R2-O) of 30/70 or more, 100 /
A zirconia-based medical material characterized by being less than 0. 5. A zirconia medical material according to claim 3 or 4, rare earth metal (R for ZrO ₂
The total molar ratio of the oxide (R1-O) of 1) and the oxide (R2-O) of the rare earth metal (R2) ((R1-O + R2-
O) / ZrO ₂₎ is zirconia medical material, which is a 1.5 / 98.5 to 5/95. 6. The zirconia-based medical material according to any one of claims 1 to 5, wherein the boron compound is
One or two selected from the group consisting of boron oxide, boron nitride, boron carbide, zirconium boride, rare earth metal (R1) boride and rare earth metal (R2) boride.
A zirconia-based medical material characterized by being one or more boron compounds. 7. The zirconia-based medical material according to any one of claims 1 to 6, wherein the content of the boron compound is 0.05 to 8 mol% in terms of boron (B). Characteristic zirconia-based medical material. 8. The zirconia-based medical material according to any one of claims 1 to 7, further comprising Al ₂ O ₃
And / or zirconia medical material characterized in that it comprises a SiO _2. 9. The zirconia-based medical material according to claim 8, wherein the boron compound is boron oxide, boron nitride, boron carbide, zirconium boride, rare earth metal (R
A zirconia-based medical material, which is one or more boron compounds selected from the group consisting of the boride of 1), a boride of a rare earth metal (R2), aluminum boride and silicon boride. 10. The zirconia-based medical material according to claim 8 or 9, wherein the content of the boron compound is 0.05 to 8% mol% in terms of boron (B) and the content of Al ₂ O ₃ . Is 0.1 to 5 mol% and the content of SiO ₂ is 0.0
A zirconia-based medical material characterized by being 5 to 1.5 mol%. 11. The zirconia-based medical material according to claim 1, which has an average particle diameter of 3 μm or less, a bulk density of 5.8 g / cm ³ or more, and mainly crystalline particles. A crystalline phase or a mixed phase of tetragonal and cubic crystals, characterized in that the material does not easily deteriorate even when used for a long time in the atmosphere or in water and steam at a temperature of 100 to 300 ° C. Zirconia medical material. 12. The zirconia-based medical material according to claim 1, which is used for the purpose of treatment or diagnosis in the medical field, such as a scalpel, scissors, tweezers, an orthodontic bracket, and a tooth. A zirconia-based medical material characterized by being used for crowns, roots, joints, bone fixing materials and the like. 13. After being calcined at 500 to 1200 ° C., the one obtained by a chemical synthesis method (neutralization coprecipitation method, hydrolysis method, alkoxide method, etc.) or a method of mixing oxide powders. The method for producing a zirconia-based medical material according to any one of claims 1 to 12, wherein the sintering is performed at 1300 to 1700 ° C.