JPS62221359A - Titanium composite material coated with calcium phosphate and its production - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is useful for implant materials such as artificial bones, teeth, tooth roots, etc., as well as their bonding materials. The present invention relates to a titanium or titanium alloy composite material coated with a calcium phosphate compound that is particularly excellent in properties, and a method for producing the same.

(Prior art and its problems) Metals have been used as biological implant materials such as artificial bones and artificial tooth roots because of their physical strength and workability.

In the past, precious metals were used because of their corrosion resistance and their impact on living organisms, but with the development of alloys that exhibit good corrosion resistance, alloy materials such as stainless steel have come to replace them. In addition, metal materials for biological implants mainly made of cobalt have been developed and used.

Among these metal materials, noble metals are stable but expensive, and have the disadvantage of having a large specific gravity and weight. Although alloys such as stainless steel have good corrosion resistance, they may contain components that pose a toxicity problem if they elute in vivo, so they are not necessarily perfect. It also has a specific gravity of around 8, which has the disadvantage of being too heavy.

Recently, titanium (d20 = 4.50) and titanium alloys have come into use because they are non-toxic, stable, have a relatively small specific gravity, are light, and are easy to handle.

All of these metal materials have sufficient mechanical strength and good workability, but they have a common drawback that they have no affinity with bone tissue in vivo if used as is.

On the other hand, research is being conducted to use ceramic materials that are more stable and lighter than metals, and α-alumina is known as a representative material. This material is not only chemically stable, but also non-toxic, lightweight, and has extremely high mechanical strength. It has the disadvantage of not having any compatibility with Stabilized zirconia has also begun to be used because of its good toughness, but it has the same drawbacks as α-alumina.

Glass materials whose surfaces are mainly porous are known as stable materials, but they have the drawbacks of insufficient mechanical strength, compatibility with living organisms, and processability.

Recently, apatite ceramics have been proposed that solve the common drawback of conventional materials, which is their lack of compatibility with living organisms. In other words, the main inorganic component of bones and teeth is a calcium phosphate compound (mainly composed of hydroxyapatite), and apatite ceramics made mainly of this component have extremely good affinity with bones, and after implantation in a living body. Assimilation is extremely good.

However, even apatite ceramics, which seem to be ideal, have drawbacks such as low mechanical strength, poor moldability, and poor workability, and the areas where they can be used are limited.

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 metal or ceramic with apatite. For this purpose, metal-ceramic and ceramic-ceramic bonding techniques are required, but at present only plasma spraying is known.

Plasma spraying is useful for such joining, but it is difficult to coat the entire surface of materials with complex shapes, and due to its characteristics, it is difficult to coat the surface metal parts of porous materials. It is impossible to do so and requires expensive equipment, the yield of expensive apatite particles is poor, and the bonding between the coating and the base material is not necessarily sufficient.

(Objective of the Invention) The object of the present invention is to create an artificial bone that is lightweight, has good workability, has sufficient mechanical strength, does not elute in the living body, and has increased compatibility in the living body such as bone tissue. The purpose of the present invention is to provide materials suitable for implant materials such as artificial tooth roots.

(Means for Solving the Problems) The present invention first provides, on a titanium or titanium alloy base material, a base layer of a calcium phosphate compound formed by heating and baking from an aqueous solution of a calcium phosphate compound in hydrochloric acid or nitric acid, and then It is a titanium composite material having a coating layer of a calcium phosphate compound formed by heating and sintering a suspension of a calcium phosphate compound. A nitric acid aqueous solution is applied and heated and fired to form a base layer of a calcium phosphate compound on the base material, and then a suspension of a calcium phosphate compound is applied thereon and heated and sintered to form a coating layer of a calcium phosphate compound. This is a method for manufacturing titanium composite materials, and its most distinctive feature is that when coating a titanium or titanium alloy base material with a calcium phosphate compound, a base layer formed by heating and sintering and a coating layer formed by heating and sintering are laminated. At the point.

The present invention will be explained in more detail below.

The present invention is a titanium composite material suitable for implant materials such as artificial bones and artificial tooth roots, in which a calcium phosphate compound coating is formed on a titanium or titanium alloy base material, and a method for producing the same.

In the present invention, calcium phosphate compounds are calcium phosphates containing fluorine, chlorine, and hydroxyl groups, including tricalcium phosphate, calcium hydrogen phosphate, calcium dihydrogen phosphate, and hydroxyapatite (calcium hydroxyphosphate). It is a general term for apatite-based compounds, and in the present invention, as the base layer and coating layer, in addition to these compounds, compounds containing some other compounds and impurities that are harmless to living organisms can be used as appropriate. In the present invention, by providing a coating of a calcium phosphate compound on the surface of titanium or a titanium alloy, it can be bonded to bones etc. with sufficiently high affinity in vivo.

The titanium or titanium alloy in the titanium or titanium alloy base material of the present invention refers to metallic titanium and, for example, Ta, Nb,
It is selected from titanium alloys to which platinum group metals, AI, V, etc. are added, and the base material may be flat in the shape of a plate, rod, etc., or have a porous surface in the form of a sponge. It may be.

Titanium or titanium alloy is used as a base material because it is non-toxic and stable in the body, and its specific gravity is approximately 60% compared to alloys such as stainless steel that are eluted.
This is because it is lightweight, and since it is made of metal, it has sufficient mechanical strength and is easy to work with. The surface of the base material may be cleaned in advance by water washing, pickling, ultrasonic cleaning, steam cleaning, etc. to remove impurities and improve affinity with the calcium phosphate compound described below. The surface can also be roughened by blasting and/or etching to improve affinity with the calcium phosphate compound described below and to activate it.

Note that etching may be performed not only by a chemical method but also by a physical method such as sputtering.

An aqueous solution of the calcium phosphate compound in hydrochloric acid or nitric acid is applied to the surface of the base material, and heated and fired to form a base layer of the calcium phosphate compound that has a strong bond with the titanium or titanium alloy of the base material. In this case, it is desirable to use a highly soluble compound such as calcium hydrogen phosphate or calcium dihydrogen phosphate as the calcium phosphate compound to form a uniform aqueous solution. In the present invention, a solution in which a calcium phosphate compound is dissolved is applied onto a base material, and then the compound is heated and precipitated from the solution. Therefore, no matter what shape the base material has, for example, a material with a porous surface, the entire surface is coated. can form a uniform coating. The reason why hydrochloric acid or nitric acid aqueous solution is used to dissolve the calcium phosphate compound is that not only is it easy to dissolve the calcium phosphate compound, but also part of the titanium or titanium alloy of the base material is dissolved during heating and baking, and the calcium phosphate compound is dissolved. This is because it can form a chemical bond with the calcium phosphate coating, which has strong adhesion resistance.

When heated and fired, the calcium phosphate compound mainly becomes hydroxyapatite or tricalcium phosphate and precipitates on the base material. The heating and firing temperature at this time is 200 to 800
If the temperature is lower than 200°C, thermal decomposition will not be sufficient and adhesion resistance to the base material will not be sufficient. When the temperature is higher than 800°C, surface oxidation of the titanium or titanium alloy base material becomes dominant, and the adhesion resistance of the base layer of the calcium sulfate compound to the base material deteriorates.

Furthermore, a coating layer of a calcium phosphate compound is laminated on this surface to a required thickness, and the calcium phosphate compound of this coating layer may be the same as or different from the calcium phosphate compound of the base layer. Since this coating layer has a calcium phosphate compound coating on the base material that is strongly bonded to the base material, it can be easily formed by a normal heat sintering method.

That is, a suspension of the desired calcium phosphate compound is applied to a substrate coated with a thin underlayer of calcium phosphate compound. The suspension concentration can be freely selected depending on the required thickness of the coating layer.

After drying, heating and sintering is performed, and the temperature ranges from 300°C to 9°C.
00℃ is good.

If the temperature is below 300°C, sintering will not proceed, and if it is above 900°C, the α-β transition point of titanium may be exceeded, which may have an adverse effect on the base material, which is not desirable. Note that the sintering temperature and time are determined depending on the state and thickness of the calcium phosphate compound. At high temperatures, tricalcium phosphate
If it is relatively low, hydroxyapatite becomes dominant.

One of the reasons why suspended S liquid is used to form the coating layer is to create unevenness on the surface of the coating layer to increase the resistance to detachment (
and increase affinity.

If necessary, the above operation can be repeated for both the base layer and the coating layer to obtain a desired thickness.

In the present invention, the base layer of calcium phosphate compound and the coating layer of calcium phosphate compound are laminated on the titanium or titanium alloy base material. A base layer of a calcium phosphate compound that is uniform and has a high affinity for the base layer is formed, and a calcium phosphate compound having the same or similar physical properties as the base layer is coated on the base layer by a sintering method, thereby forming a bond between the base layer and the covering layer. It provides a strong bond between the two and forms a strong calcium phosphate compound,
This is to provide a titanium composite material that has a high affinity with the base material and has sufficiently high strength, and the strength of the coating layer is high when only a single coating layer is formed on the base material by heating and sintering. has low affinity with the base material and is easily peeled off, making it impossible to obtain a composite material useful as an implant material as in the present invention.

(Examples) Examples of the present invention will be described below, but these Examples do not limit the present invention.

Calcium hydrogen phosphate (CaHPO4) was dissolved in a 20% aqueous nitric acid solution to prepare a coating solution of a calcium phosphate compound containing 10% calcium hydrogen phosphate.

The surface of a JIS grade 1 titanium material measuring 10cm long x 10cm wide x 3u thick was blasted using a #80 steel grid to roughen the surface, and then etched in a 15% oxalic acid aqueous solution at 95°C for 6 hours. Ta.

The above coating solution was applied to the titanium activated by this etching, dried at 80°C for 20 minutes, and then heated at 500°C for 30 minutes.
It was heated and baked for 0 minutes.

When the coating and firing operations were repeated twice, a strong base layer made of tricalcium phosphate with a thickness of approximately 2 μm was formed on the titanium surface. Analysis using an X-ray microanalyzer revealed that in addition to tricalcium phosphate, the underlayer contained approximately 10% titanium.

A suspension of a calcium phosphate compound was further applied to the titanium plate having the tricalcium phosphate base layer. The suspension was prepared by grinding tricalcium phosphate reagent (special grade) powder in an agate mortar for 10 hours and dispersing it in a 5% aqueous hydrochloric acid solution.

The titanium plate coated with the suspension was dried at 80°C for 1 hour and further sintered at 700°C for 3 hours. This operation was repeated twice to obtain a titanium plate having a strong and uniform sintered coating layer consisting mainly of tricalcium phosphate and having a thickness of approximately 100 μm.

Dissolve Calcium Hydrogen Phosphate in a 20% aqueous solution of hydrochloric acid,
% of calcium hydrogen phosphate was prepared. This coating solution was applied with a brush onto a titanium plate prepared in the same manner as in Example 1, dried at 80° C. for 20 minutes, and then baked for 20 minutes at 600° C. in an argon atmosphere containing 10% oxygen. This operation was repeated three times to form a strong base layer made of tricalcium phosphate with a thickness of about 2 μm on the titanium plate.

When analyzed using an X-ray microanalyzer in the same manner as in Example 1, it was found that the underlayer contained about 25% titanium, presumably from the titanium plate. A suspension of a calcium phosphate compound was applied thereto, dried at 80°C for 1 hour, and then heated and sintered at 800°C for 2 hours in an argon atmosphere. The suspension was prepared by dissolving calcium hydroxide in a 10% nitric acid aqueous solution and adding Ca''
Calcium hydrogen phosphate was added so that the molar ratio of ions to PO,''- ions was 3:2, and the same tricalcium phosphate powder as in Example 1 was further added to prepare the sample.

As a result, a titanium plate having an extremely strong coating layer of a calcium phosphate compound having a thickness of approximately 50 μm was obtained.

For reference, heat sintering after applying the suspension was performed at 950°C for 1
After a period of time, significant grain growth of titanium, which was thought to be caused by titanium transition, was observed, and part of the coating peeled off.

Example 3 A base layer coating of a calcium phosphate compound was formed on titanium treated in the same manner as in Example 1 in the same manner as in Example 2. As a reference, a titanium plate without this underlayer coating was prepared.

These were coated with a suspension of a calcium phosphate compound containing hydroxyapatite as a main component, dried at 80°C for 1 hour, and heated and sintered at 800°C for 2 hours with air removed.

The suspension is made by dissolving calcium hydroxide in a 10% nitric acid aqueous solution, adding calcium hydrogen phosphate to the solution so that the molar ratio of Ca2' ions and PO43- ions is 5:3, and then adding hydroxyapatite to the solution. It was prepared by adding powder that had been finely ground in a mortar for 10 hours.

On a titanium plate on which a base layer coating was formed with calcium hydrogen phosphate and a coating layer made from a suspension was baked on top of it, the formation of an extremely strong hydroxyapatite coating with a thickness of approximately 50 μm was observed. The titanium plate that was not coated with calcium hydrogen phosphate as a base layer was able to form a hydroxyapatite coating in the same way as the titanium plate that had the coating formed, but the coating was easily peeled off by a tape test. It was so weak that it was Note that the tape test is a test to see if cellophane tape, Scotch tape, etc. is applied to the surface of the coating and the transfer tape is peeled off to see if the coating will remain attached to the tape.If the coating strength is weak, the coating will remain attached to the tape. It will peel off as you leave it on.

(Effects of the Invention) First, the present invention uses titanium or titanium alloy as the base material, so when the composite material of the present invention is used as an artificial bone or artificial tooth root, it is harmless to living organisms, stable, and does not elute. Moreover, it is lightweight, has sufficient mechanical strength, and is easy to work with.

Second, since the surface of titanium or titanium alloy is coated with a calcium phosphate compound, it has a sufficiently high affinity in vivo and can be bonded easily and with sufficient strength.

Thirdly, since it is a composite coating in which a base layer is first formed on the surface of the base material by heating and baking a calcium phosphate compound, and then a coating layer is formed on top of that by heating and sintering, the base material and base layer and the base layer and the coating layer are separated. The affinity between each of them is very large, and the surface layer is a layer formed by heating and sintering with high strength, so the overall strength is high.

Fourth, when forming the base layer, a solution of a calcium phosphate compound is applied to the base material and the calcium phosphate compound is precipitated from the solution, so it can be applied uniformly over the entire surface of the base material, regardless of its shape. Furthermore, the yield of the calcium phosphate compound is good, and the state of the coating can be easily controlled to form a high-quality coating.

Claims (7)

[Claims] (1) On a titanium or titanium alloy base material, a base layer of a calcium phosphate compound is formed by heating and firing from an aqueous solution of a calcium phosphate compound in hydrochloric acid or nitric acid, and on top of that, a base layer is formed by heating and sintering a suspension of the calcium phosphate compound. A titanium composite material characterized by having a coating layer of a calcium phosphate compound. (2) The titanium composite material according to claim (1), wherein the calcium phosphate compound of the base layer and/or the coating layer is mainly hydroxyapatite and/or tricalcium phosphate. (3) Activate the surface of the titanium or titanium alloy base material, apply a hydrochloric acid or nitric acid aqueous solution of a calcium phosphate compound, heat and bake to form a base layer of a calcium phosphate compound on the base material, and then apply A method for producing a titanium composite material, comprising applying a suspension of a calcium phosphate compound and heating and sintering to form a coating layer of a calcium phosphate compound. (4) The manufacturing method according to claim (3), wherein the calcium phosphate compound formed as the base layer and/or the coating layer is mainly hydroxyapatite and/or tricalcium phosphate. (5) The manufacturing method according to claim (3), wherein the surface of the titanium or titanium alloy base material is activated by blasting and/or etching. (6) Claim (3) in which the acid aqueous solution of the calcium phosphate compound is heated and baked at a temperature of 200 to 800°C.
The manufacturing method described in section. (7) Formation of a coating layer of a calcium phosphate compound by applying a suspension of a calcium phosphate compound, and after drying,
Claim No. 3 (3), which is performed by heating and sintering at a temperature of 00°C.
).