JPH0214061B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is useful for implant materials such as artificial bones, teeth, tooth roots, etc., and their bonding materials, and has a surface that is compatible with bone and tooth tissues. The present invention relates to a method for producing a composite material comprising a metal substrate coated with a particularly excellent calcium phosphate compound.

(Prior art and its problems) Biological implant materials such as artificial bone and artificial tooth roots are
When a bone is lost or a tooth falls out due to an accident, etc., it can be attached to the remaining bone or implanted in the jawbone, allowing it to be used in a form similar to that of the original, allowing people to maintain a comfortable lifestyle. Recently, it has been attracting attention because of its However, since these implant materials are to be implanted within the human body, they must be harmless to the human body, and they must also be strong enough, processable, non-eluting, have an appropriate specific gravity, and be compatible with living organisms. It must also meet various conditions such as affinity.

Traditionally, metals such as precious metals, alloys such as stainless steel, ceramics such as α-alumina, and apatite ceramics have been used as implant materials, but these materials are toxic, have insufficient strength, and are difficult to process. It has at least one of the following disadvantages: lack of oxidation, elution, and lack of affinity with living organisms.

In order to eliminate these drawbacks, it is desired to develop a biocompatible metal or ceramic material as a composite material by coating the surface of the metal or ceramic with apatite. For this purpose, metal-ceramic and ceramic-ceramic bonding techniques are required, but until now only plasma spraying was known. However, although plasma spraying is useful for such bonding, it has drawbacks such as poor yield of expensive apatite particles and insufficient bonding between the coating and the base material. Furthermore, if the conditions are too severe, a portion of the material will decompose during the thermal spraying process, making it necessary to add additional treatment such as crystallization.

In order to eliminate these conventional drawbacks, the applicant has developed a coating layer consisting of a metal substrate and a calcium phosphate compound, which can be manufactured without using a thermal spraying method, and an intermediate layer containing a calcium phosphate compound. (Patent Application No. 61-64012, No. 61-64013)
We have proposed implant materials that are firmly bonded (Japanese Patent Application No. 61-169547) or without interposition (Japanese Patent Application No. 61-169547).

These implant materials have a sufficiently high bonding strength between the metal base material and the calcium phosphate compound coating layer, but when implanted in a living body, over a long period of time they will become compatible with the bone tissue including the teeth. A coating of highly resistant calcium phosphate compounds can be assimilated into the bone tissue, ultimately resulting in direct contact between the bone tissue and the metal substrate. However, since the affinity between the metal base material and bone tissue is insufficient, degeneration of the bone tissue may occur, worsening the adhesion of the two, or in the worst case, causing the metal base material to fall off.

(Objective of the Invention) The object of the present invention is to provide an artificial bone and an artificial tooth root that have good workability and sufficient mechanical strength, and can also improve affinity with bone tissue and maintain stable adhesion over a long period of time. It is an object of the present invention to provide a method for manufacturing a composite material suitable for implant materials such as the following.

(Means for Solving the Problems) The present invention firstly heats and oxidizes a metal base material to form an oxide layer of the base material component on the surface thereof, and further adds a calcium phosphate compound to the surface of the oxide layer. A method for producing a calcium phosphate compound-coated composite material characterized by forming a coating layer by a pyrolysis method. After turning into a monster,
A calcium phosphate compound characterized by comprising heating and oxidizing the metal base material to form an oxide layer of the base material component on the surface thereof, and further forming a coating layer of a calcium phosphate compound on the surface of the oxide layer. This is a method for producing a coated composite material, and the main feature is that between the metal base material and the coating layer of the calcium phosphate compound, the metal base material has relatively good affinity in vivo and has sufficiently high corrosion resistance. By not only heating and oxidizing the metal base material but also combining the heating oxidation and other means, the oxide layer constituting the metal substrate is thicker than the heating oxidation alone and has excellent corrosion resistance and affinity in vivo. Forming a layer of calcium phosphate compound on the surface prevents direct contact between the metal base material and the bone tissue and deterioration of adhesion between the two even if the coating layer of the calcium phosphate compound on the surface is absorbed by the bone tissue. be.

The present invention will be explained in more detail below.

The present invention heats and oxidizes a metal base material so that the surface of the metal base material has extremely excellent corrosion resistance in vivo.
A calcium phosphate compound-coated composite material suitable as an implant material, in which an oxide layer of the metal base component is formed, and then a coating layer of a calcium phosphate compound having extremely good affinity with living organisms, such as hydroxyapatite, is formed on the surface of the oxide layer. This manufacturing method makes it possible to provide a composite material that can be bonded to bone tissue, etc. with a sufficiently large affinity in the living body, maintain stable affinity for a long period of time, and have no adverse effects on the living body. .

The metal base material in the present invention refers to a base material selected from titanium, titanium alloys, stainless steel, chromium-cobalt-based alloys, etc., which are stable in vivo. Titanium or titanium alloy here is selected from metallic titanium and titanium alloys to which Ta, Nb, platinum group metals, Al, V, etc. are added, and stainless steel is
JIS (Japanese Industrial Standards) SUS304, 310, and 316, etc., and cobalt-chromium-based alloys include corrosion-resistant alloys including cobalt-chromium alloys for biological implants. Metal base materials made of such metals may be flat, plate-like, rod-like, etc., may have a sponge-like porous surface, or may be expanded mesh or perforated plates. good. The use of these metals as base materials is
This is because it has sufficient mechanical strength and is easier to work with than sintered bodies or glass, and the surface of the base material has been cleaned in advance by water washing, pickling, ultrasonic cleaning, steam cleaning, etc. Impurities may be removed to improve the uniformity of the oxide layer formed later, and if necessary, the surface may be roughened by blasting and/or etching to form a coating layer of a calcium phosphate compound as described below. Activation can also be performed while improving affinity with. Note that etching may be performed not only by a chemical method but also by a physical method such as sputtering.

Next, the surface of the metal base material is heated and oxidized to form an oxide layer of the metal component of the metal base material on the surface. The metal base material is directly exposed to an oxidizing atmosphere such as air.
When heated to about 400 to 1000°C, an oxide layer is formed with a thickness depending on the type of metal base material. Since the thickness of the oxide layer formed by simple thermal oxidation is relatively thin and may be insufficient for improving corrosion resistance and affinity in vivo, the present invention focuses on forming a thicker oxide layer. With the intention of The oxide layer is formed by a decomposition method, and the thickness of the oxide layer is increased by the oxidation effect of the solvent used during the thermal decomposition.

For acid treatment, the metal substrate may be treated by a coating method, dipping method, etc. using a solution containing a corrosive inorganic or organic acid such as hydrochloric acid, sulfuric acid, nitric acid, or oxalic acid, and then heated at 300 to 800°C. An oxide layer is formed by heating to a certain degree. The acid treatment corrodes the surface of the metal substrate before heating, and the effect of heating extends deep into the layer, resulting in the formation of a thicker oxide layer.
For example, in the case of titanium or titanium alloys, when heated without acid treatment, a pale yellow oxide is formed, but when heated after acid treatment, a relatively thick blue oxide layer is formed, and the oxide is Since the surface remains in a corroded or roughened state even after formation, it becomes possible to form a more strongly coated layer of calcium phosphate compound, which will be described later. The acid treatment also treats stainless steel, chromium-cobalt-based alloys, and other metals at lower temperatures.
A thick and stable oxide layer can be formed.

In addition, when the metal base material is stainless steel or chromium-cobalt based alloy, if an acid containing halogen such as hydrochloric acid is used as the inorganic acid, the halogen may remain in the oxide layer and have an adverse effect. , it is preferable to use sulfuric acid or nitric acid.

The metal hydride on the surface of the metal substrate is usually formed at the same time as the above-described acid treatment of the metal substrate. For example, in an oxidizing atmosphere such as air,
A corresponding oxide layer is obtained when heated to about ~700°C. The thickness of the metal hydride layer formed by the acid treatment reaches 0.1 to several tens of μm. For example, for titanium or titanium alloys, 20% in boiling hydrochloric acid
A metal hydride layer with a thickness of 10-20 μm was obtained by treatment for ~40 minutes, and the surface roughness became large after treatment in 30% oxalic acid at 100 °C for 4-8 hours.
A metal hydride layer with a matte texture and a thickness of 10 to 20 μm is also obtained. The metal hydride is easily oxidized by heating to form an oxide layer with a similar thickness. Similarly, in the case of stainless steel or chromium-cobalt based alloys, metal hydrides with a thickness of 10 to 20 μm can be obtained by treating them in nitric acid at room temperature for 2 to 10 hours.

In order to form the metal hydride, in addition to the acid treatment described above, a method of electrolytically forming the metal hydride by applying current to the metal base material as a cathode can also be adopted. This method is particularly effective for titanium or titanium alloys; for example, when treated in a 15% sulfuric acid aqueous solution at 60° C. for about 5 hours, a metal hydride coating of 0.5 to 10 μm can be formed. The hydride can be converted to the corresponding stable oxide by heating to 400-700°C in the case of titanium or titanium alloys and 400-900°C in the case of other metals.

Next, a coating layer of a calcium phosphate compound is formed on the oxide layer of the metal base material on which the oxide layer has been formed in this manner. In the present invention, the term "calcium phosphate compound" refers mainly to hydroxyapatite, and also to tricalcium phosphate, calcium hydrogen phosphate, and calcium dihydrogen phosphate, which are thought to be by-produced by heating and calcination of hydroxyapatite according to the method of the present invention. In addition, it contains a calcium phosphate compound formed by impurity components or components in the oxide layer and hydroxyapatite.

The method of forming the coating is not particularly limited if a metal hydride is formed on the surface of the metal base material before heating oxidation, but if the hydride is not formed, an oxide formed by employing a thermal decomposition method is used. Make the material layer thicker.

As mentioned above, the plasma spraying method uses expensive hydroxyapatite and has problems such as insufficient yield, but has the advantage of being able to easily form a coating. However, in the past, when spraying directly onto metal, the spraying had to be carried out under harsh conditions in order to obtain sufficient adhesion, which resulted in the decomposition of some of the expensive hydroxyapatite. However, in the present invention, sufficiently strong adhesion can be obtained even when thermal spraying is performed under conditions in which the hydroxyapatite, which is an oxide layer underlying the calcium phosphate compound coating layer, does not decompose.

The thermal spraying conditions are, for example, an atmosphere consisting of argon gas and hydrogen, and a power of about 30kW is sufficient.
The particle size of the hydroxyapatite is preferably a medium particle size of about 125 to 345 mesh.

When a thermal decomposition method is adopted, a calcium phosphate compound, preferably hydroxyapatite, is dissolved, preferably saturated, for example, in an aqueous solution of nitric acid, and applied to the surface of the oxide layer, and heated and fired to remove the oxidation of the metal base material. Forms a coating layer that has strong adhesion to the material layer. The heated and calcined product in this case is a calcium phosphate compound mainly composed of hydroxyapatite. The optimal temperature for heating and firing conditions changes depending on the liquid used, especially the nitric acid concentration.The higher the nitric acid concentration, the higher the optimal temperature is.
℃, 450-800℃ is optimal for 60% nitric acid. The heating and firing temperature is preferably 300 to 800°C. If it is less than 300°C, the strength of the calcium phosphate compound coating layer will be insufficient, and if it is higher than 800°C, the oxidation rate of the metal base material will increase, causing the metal base material and the oxide layer to Peeling is likely to occur between the two. The heating and baking may be performed in an oxidizing atmosphere such as air, but is preferably performed in an inert atmosphere such as argon.

In addition, a coating layer can be formed by applying a solution of a mixture of calcium carbonate and calcium phosphate in an appropriate ratio and heating and baking the mixture in an oxidizing or inert atmosphere. In this case, hydrothermal treatment is also required. It is preferable to improve crystallinity.

Through the above operations, an implant that has good workability, sufficient mechanical strength, and high affinity with in-vivo bone tissue and maintains stable adhesion with the living body for a long time. material can be obtained.

(Examples) The present invention will be explained in more detail with reference to Examples below, but these Examples do not limit the present invention.

Example 1 A rolled plate of SUS316L with a thickness of 1 mm is 40 mm long and 20 mm wide.
It was cut to a size of mm, and its surface was roughened by blasting using a #80 steel shot to obtain a metal base material. This metal substrate was degreased with trichlorethylene vapor and then immersed in a 25% by weight aqueous nitric acid solution at room temperature for 30 minutes to remove surface deposits such as blast sand residue.

A 30% nitric acid aqueous solution was applied to the thus cleaned stainless steel base material, left to stand at room temperature, and after drying, the material was placed in a Matsufuru furnace at 600°C with air flowing through it and heated for oxidation for 15 minutes. When this operation was repeated three times, a stainless steel base material having a blue oxide coating layer with a thickness of approximately 5 μm was obtained.

This oxide coating layer was found to be extremely strong as a result of a tape test.

Next, a calcium phosphate compound coating layer mainly composed of hydroxyapatite was formed on this oxide coating layer by the following method. The coating layer was formed by dissolving 3 g of hydroxyapatite powder in 10 g of a 25% nitric acid aqueous solution and applying it to the oxide-coated base material in a Matsufuru furnace flushed with argon.
Obtained by thermal decomposition at 500°C for 10 minutes.
Further, the coating-heating operation was repeated three times.

The produced calcium phosphate compound coating layer was substantially composed of hydroxyapatite and was sufficiently firmly attached to the substrate via the oxide layer.

Example 2 A JIS Class 1 titanium rolled plate with a thickness of 1 mm is 40 mm long and 20 mm wide.
It was cut out to a size of mm and pretreated in the same manner as in Example 2 to obtain a metal base material.

The titanium base material was placed in a 30% by weight aqueous sulfuric acid solution at 95°C.
Soaked for 15 minutes. Due to the immersion, titanium was eluted and hydrogen was violently generated. This titanium base material was taken out and placed in a Matsufuru furnace maintained at 550°C for 20 minutes. Through this operation, a strong blue titanium oxide coating was formed. The titanium base material coated with titanium oxide was coated with hydroxyapatite powder prepared to have a particle size of 125 to 345 mesh by plasma spraying.

The conditions for the plasma spraying method are plasma Ar: H ₂ =
5:1 (volume), arc voltage 60V, arc current
It was 500A. This thermal spraying made it possible to form a strong coating of hydroxyapatite containing tricalcium phosphate.

Example 3 A JIS Class 1 titanium rolled plate having a thickness of 1 mm was pretreated in the same manner as in Example 1, and was used as a metal base material. Using the titanium base material as a cathode, in a 20% aqueous hydrochloric acid solution at 60°C,
Electrolysis was carried out for 30 minutes at a current density of 100 A/dm ² .
As a result of this operation, the surface of the titanium base material became grayish white. When this was examined using X-ray diffraction, it was found that on the surface
It was found that TiH ₂ was generated.

The titanium substrate was heated at 450°C in a Matsufuru furnace through a gas mixture consisting of 25% oxygen and 75% nitrogen.
Heat for 30 minutes. The surface became horizontally brown, and X-ray diffraction revealed that a rutile-type oxide was formed on the surface.

On the titanium base material with this surface oxide layer formed,
A hydroxyapatite layer was formed under the same conditions as in Example 1.

The hydroxyapatite layer was extremely strong, and no peeling was observed even in a tape test.

(Effects of the Invention) In the present invention, firstly, particularly corrosion-resistant titanium, titanium alloy, stainless steel, chromium-cobalt-based alloy, etc. are used as the metal base material, and the surface thereof further contains the metal component of the metal base material. The metal oxide layer is formed by heating and oxidizing the metal base material, and when the composite material related to the present invention is used as an artificial bone or artificial tooth root, it is harmless to living organisms, stable, and has almost no possibility of elution. It has sufficient mechanical strength and is easy to work with.

Second, since the surface of the metal base material is coated with a calcium phosphate compound represented by hydroxyapatite, it has a sufficiently high affinity in vivo and can be easily bonded to bones, etc. in vivo with sufficient strength. can do.

Third, as mentioned above, since a metal oxide layer is formed on the surface of the metal base material, the calcium phosphate compound, which has particularly excellent affinity, is absorbed into bone tissue over a long period of time after implantation. Even later, the oxide layer formed on the metal base material prevents direct contact between the bone tissue and the metal base material, which is based on the insufficient affinity between the bone tissue and the metal base material. By preventing deterioration of the adhesion between the two, it is possible to use the calcium phosphate compound-coated composite material of the present invention for a long period of time without causing any change in stability as an implant material.

Fourth, a metal oxide layer is formed between the calcium phosphate compound coating layer and the metal base material, and the coating layer and metal oxide layer have a sufficiently strong bond even when sprayed under relatively mild conditions. Therefore, when forming the coating layer, it becomes possible to use a thermal spraying method which is easy to form a coating but could not be used conventionally due to the decomposition of hydroxyapatite.

Fifth, before forming an oxide layer, a hydride is formed on the surface of the metal base material, and the thickness of the oxide layer formed by heating oxidation is compared with the thickness of the oxide layer formed by normal heating oxidation. or to adopt a thermal decomposition method in which the oxide layer is oxidized by a solvent and the thickness of the oxide layer becomes thicker, or the coating layer of the calcium phosphate compound formed on the oxide layer is oxidized by a solvent. , the thickness of the oxide layer becomes thicker than in the case of normal thermal oxidation, and the corrosion resistance and affinity in vivo are improved.

Claims (1)

[Claims] 1. A metal base material is heated and oxidized to form an oxide layer of the base material component on the surface thereof, and a coating layer of a calcium phosphate compound is further formed on the surface of the oxide layer by a pyrolysis method. A method for producing a composite material coated with a calcium phosphate compound, characterized by comprising the steps of: 2. After pre-treating the surface of the metal base material to make the surface of the metal base material into a metal hydride, heating and oxidizing the metal base material to form an oxide layer of the base material component on the surface, and further A method for producing a calcium phosphate compound-coated composite material, comprising forming a coating layer of a calcium phosphate compound on the surface of an oxide layer. 3. The manufacturing method according to claim 2, wherein the surface of the metal base material is treated with an acid to convert the surface of the metal base material into a metal hydride. 4. The manufacturing method according to claim 2, wherein the metal base material is previously energized as a cathode in an electrolytic bath to convert the surface of the metal base material into a metal hydride.