JPH08117324A - Method for manufacturing a bio-implant material - Google Patents

Abstract

PURPOSE: To provide a method for manufacturing a bio-implant material with a coating layer on the surface of a metal substrate comprising titanium as a principal component, such as titanium metal or titanium alloy, the layer having a good adhesive property to bones and hardly peelable from the substrate. CONSTITUTION: A paste containing metal powder of titanium or titanium alloy and a bio-active substance powder such as calcium phosphate compound or bio-active glass, etc., is applied to the surface of a metal substrate comprising titanium or titanium alloy, and then heat-treated in the vacuum or inert gas atmosphere so as to form a coating layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an artificial bone, an artificial hip joint,
The present invention relates to a method for producing a biomedical implant material useful as a substitute material for biomedical hard tissues such as artificial tooth roots.

[0002]

2. Description of the Related Art Conventionally, as a bioimplant material for repairing a bone defect or the like, one made of titanium metal or titanium alloy has been known. Since such an implant material has biocompatibility and high mechanical strength, it is used in a portion to which a large load is applied, such as a femur or a hip joint.

However, the above-mentioned implant materials are
Due to the weak force of conducting the bone, it takes time for the bone to reach the surface of the implant material and then adhere. Therefore, there is a problem that the patient cannot stay away from the bed for a long period of time, and the physical and mental burden on the patient is large.

In addition, bioactive inorganic materials, such as inorganic materials containing hydroxyapatite and apatite, are known to have the property of reacting with the surrounding bone tissue in the living body and forming a chemical bond with the bone. However, these materials have the drawback of low mechanical strength.

Therefore, a composite material in which a surface of a metal base made of titanium metal or a titanium alloy is coated with a bioactive inorganic material such as apatite or bioactive glass by plasma spraying, or a composite material in which the bioactive glass is baked on the surface of the metal base Is proposed.

[0006]

The above-mentioned composite material has high mechanical strength, excellent affinity, and good adhesiveness with bone, but has the following drawbacks.

First, when plasma-spraying a bioactive inorganic material on the surface of a metal substrate, apatite and glass are relatively difficult to spray because of poor thermal conductivity, and the substrate and the coating layer are mechanically bonded to each other. The coating layer is easy to peel off because it does not exist. Moreover, it is difficult to control the composition and crystal structure of the thermal spray material, and it is difficult to form a desired coating layer.

When bioactive glass is baked on the surface of a metal substrate, a difference in expansion between the substrate and the glass causes stress at the bonding interface between them, the glass layer is easily peeled off, and the reaction between titanium and glass causes mechanical stress. A weak layer is produced. Moreover, the coating layer made of glass has a drawback that the mechanical strength is weak.

An object of the present invention is to provide a bioimplant in which a coating layer having excellent adhesiveness to bone and which is not easily peeled off from the base is formed on the surface of a metal base containing titanium as a main component such as titanium metal or titanium alloy. It is to provide a method for manufacturing a material.

[0010]

According to the method for producing a bioimplant material of the present invention, a paste containing a metal powder containing titanium as a main component and a bioactive substance powder is applied to the surface of a metal base containing titanium as a main component. After that, heat treatment is performed in a vacuum or an inert gas atmosphere.

The metal containing titanium as a main component in the present invention means titanium metal and titanium alloy. As a titanium alloy, Ti, as a main component, Al, Sn, Zr, M
Alloys containing o, Ni, Pd, Ta, Nb, V, Pt, etc. can be used. Among them, Ti-6Al-4V can be used.
Preference is given to using alloys.

The metal powder contained in the paste is the same material as the above substrate or titanium hydride in powder form. As the bioactive material powder, apatite, three or calcium phosphate compounds such as calcium phosphate (TCP) and the _{like, MgO-CaO-SiO 2 -P} 2
O ₅ system and _{Na 2 O-CaO-SiO 2} -P 2 O 5 system uses a powder of bioactive glass typified. When bioactive glass powder is used, it is preferable to heat and crystallize it because the strength of the coating layer is improved. The average particle size of these powders is preferably about 0.5 to 100 μm in consideration of sinterability and reactivity between the particles and the substrate. Further, the mixing ratio of the metal powder and the bioactive substance powder is selected in the range of 5:95 to 95: 5 of metal powder: bioactive substance powder in volume% in consideration of the balance between bioactivity and strength. The reason for this is that if the amount of metal powder is less than 5% by volume, the coating layer is likely to peel off from the substrate, whereas if it is more than 95% by volume, the adhesion to bone is reduced.

In the present invention, it is necessary to prepare a paste by mixing the metal powder and the bioactive substance powder, and then adding the binder and the solvent thereto.

Ethyl cellulose, polyethylene glycol, polyisobutyl acrylate, etc. can be used as a binder for preparing the paste, and the solvent is
Alcohol, terpineol, water, etc. can be used. The mixing ratio of the powder, the binder and the solvent is appropriately adjusted according to the method of applying the paste so as to have an appropriate viscosity characteristic.

As a method of applying such a paste to a metal substrate, any method such as dipping, brush coating or spraying can be adopted. After applying the paste to the surface of the metal substrate by these methods, Heat treatment.

However, since the metal containing titanium as a main component is easily oxidized and the oxide film formed is extremely brittle, the heat treatment is performed in an atmosphere in which oxygen does not exist. Therefore, before carrying out this heat treatment, it is necessary to dry the solvent in advance and perform calcination to remove the binder. Heat treatment is 5 ×
It is performed at a temperature of about 850 to 1300 ° C. in a vacuum of 10 ⁻⁵ Torr or more or in an atmosphere of an inert gas such as argon gas. The temperature at this time is determined in consideration of the degree of sintering of the metal powder, the degree of adhesion between the coating layer and the metal substrate, the degree of precipitation of the bioactive substance powder crystals, and the like.

Thus, a coating layer composed of a metal containing titanium as a main component and a bioactive substance is formed on the surface of the metal substrate, and the thickness thereof is preferably about 50 to 100 μm. Further, in the present invention, it is preferable to roughen the surface of the metal substrate in advance by sandblast or the like because the adhesiveness with the coating layer is further improved.

[0018]

The bioimplant material obtained by the production method of the present invention comprises a metal base body containing titanium as a main component and a layer of titanium metal and a bioactive substance coated on the surface of the metal base body. When it is inserted, it joins to the bone in a short period of time, and a high bond strength is obtained between the metal substrate and the coating layer because part of them is made of the same material.

[0019]

EXAMPLES Hereinafter, the method for producing a bioimplant material of the present invention will be described in detail based on examples.

Table 1 shows samples (No. 1) of the examples of the present invention.
7 to 7) and a comparative sample (No. 8).

[0021]

[Table 1]

As a metal substrate, 10 × 15 × 0.2 ^t m
A Ti-6Al-4V alloy with a size of m was used and roughened by sandblasting so that the surface roughness of this substrate was about 10 μm in R _max .

Titanium powder, bioactive glass powder and apatite powder were prepared as powders constituting the coating layer. As the bioactive glass, two types shown in Table 2 were prepared. The titanium powder has a maximum particle size of 45 μm and an average particle size of 20 μm, and the bioactive glass powder has a maximum particle size of 4 μm.
The average particle size is 5 μm and the average particle size is 15 μm. The maximum particle size of the apatite powder is 45 μm and the average particle size is 20 μm.

[0024]

[Table 2]

Next, titanium powder, bioactive glass powder and apatite powder were mixed in the proportions shown in Table 1, and to 100% by volume of this mixed powder, 2.5% by volume of polyisobutyl acrylate and 47.5 of terpineol were mixed. Volume% was added to prepare a paste.

Then, this paste was applied to the surface of the above-mentioned metal substrate by a brush coating method, dried at 150 ° C., and then held at 400 ° C. for 30 minutes to degrease the binder. Next, this was put into a vacuum firing furnace, held at a vacuum degree of 10 ⁻⁶ Torr, and fired under the heat treatment conditions shown in Table 1 to prepare a sample. With respect to each of these samples, the peeling strength of the coating layer, the bioactivity, and the adhesiveness with bone were examined.

As a comparative example, a sample was prepared under the same conditions as those of the examples except that only the same bioactive glass powder as that described above was used. It was set to 8. Also for the sample of this comparative example, the peeling strength of the coating layer, the bioactivity and the adhesiveness to bone were examined.

As a result, in each of the samples of Examples, the peeling strength of the coating layer was as high as 150 kgf / cm ² or more, and the bioactivity and the adhesiveness to bone were good. In contrast,
No. which is a comparative example. Sample No. 8 was inferior in peeling strength of the coating layer.

The peeling strength was 2 times as much as that of the coating layer 11 located on the opposite surface of the sample 10 as shown in FIG.
The metal square bars 12 of the book are adhered using an adhesive agent 13, the respective square bars 12 are pulled in opposite directions, and the force when the coating layer 11 is peeled off is obtained. In addition, the bioactivity was obtained by making a simulated body fluid prepared in the same manner as the ion concentration of human body fluid, immersing each sample in this simulated body fluid, and examining the presence or absence of apatite crystal formation on the surface. . Furthermore, the adhesiveness to bone was evaluated by implanting each sample in the tibia of a rabbit for 8 weeks, cutting out the material together with the bone, and embedding it in resin.
This is a histological observation of a sample sliced in the cross-sectional direction, and was performed by evaluating the presence or absence of bone tissue formed on the material surface.

[0030]

INDUSTRIAL APPLICABILITY As described above, the bioimplant material of the present invention has excellent biocompatibility, high mechanical strength, and can be bonded to bone in a short period of time, and the coating layer is difficult to peel off from the base material.
The initial fixation after surgery is good, the patient can leave the bed early, and the physical and mental burden on the patient can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a method for measuring peeling strength of a coating layer.

[Explanation of symbols]

 10 samples

Claims (1)

[Claims] 1. A surface of a metal substrate containing titanium as a main component is coated with a paste containing a metal powder containing titanium as a main component and a bioactive substance powder, and then heat treated in a vacuum or an inert gas atmosphere. A method for producing a characteristic bioimplant material.