JPS62227094A - Production of composite titanium material coated with calcium phosphate compound - Google Patents

Abstract

PURPOSE:To enhance the affinity for bone tissure and to improve the workability by successively forming an underlayer and a coating layer each contg. a calcium phosphate compound as the principal component on the surface of a Ti material and by modifying the coating layer by hydrothermal treatment. CONSTITUTION:The surface of a Ti (alloy) material is activated and a soln. prepd. by dissolving a calcium phosphate compound such as tricalcium phosphate in an aqueous soln. of hydrochloric acid or nitric acid is applied to the activated surface and baked by heating to form a rigid underlayer. A suspension prepd. by dispersing the calcium phosphate compound in an aqueous soln. of hydrochloric acid or the like is applied to the underlayer and sintered by heating to form a coating layer. This coating layer is modified by hydrothermal treatment to increase the degree of crystallinity. The resulting composite Ti material coated with the calcium phosphate compound is light in weight and has satisfactory mechanical strength, so it is suitable for use as an implant material such as an artifical bone or an artifical dental root.

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 method for producing a titanium or titanium alloy composite material coated with a calcium phosphate compound that has particularly excellent properties.

(Prior art and its problems) Biomedical implant materials such as artificial bones and artificial tooth roots can be attached to the remaining bone or implanted into the jawbone in the event of bone loss or tooth loss due to an accident, etc. It has recently been attracting attention because it can be used in a form similar to that of natural substances and allows us to maintain a comfortable life. However, since these implant materials are to be implanted into 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 suitable for living organisms. It must also meet various conditions, such as having compatibility with

Traditionally, metals such as precious metals, alloys such as stainless steel, and ceramics such as α-alumina have been used as implant materials, but these materials are toxic, have insufficient strength, lack workability, etc. They have at least one of the disadvantages of elution and too high specific gravity, and a common disadvantage is that they lack affinity for living organisms.

Recently, apatite ceramics that solve this affinity have been proposed. The inorganic component of bones and teeth is a calcium phosphate compound (mainly composed of hydroxyapatite), and the main component of apatite ceramics is also a calcium phosphate compound, so the affinity between the two is extremely good, and it is easy to assimilate after implantation in a living body. is very good.

However, like the conventional materials mentioned above, this apatite ceramic also has drawbacks such as low strength and poor workability, and its uses 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 entire surface of porous materials. This method has drawbacks such as the need for expensive equipment, poor yield of expensive apatite particles, and insufficient bonding between the coating and the base material.

The present applicant filed two patent applications on March 24, 1986 regarding the invention of titanium composite materials.

The present invention relates to an improvement of the above invention.

(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 high m-compatibility in the living body such as bone tissue. The object of the present invention is to provide a method for manufacturing a titanium composite material suitable for implant materials such as artificial tooth roots.

(Means for Solving the Problems) The present invention involves activating the surface of a titanium or titanium alloy base material, coating the base material with an aqueous solution of hydrochloric acid or nitric acid in which a calcium phosphate compound is mainly dissolved, and then heating and baking it. forming a base layer containing a calcium phosphate compound on the base material,
Next, a suspension of a calcium phosphate compound is applied thereon and heated and sintered to form a coating layer of the calcium phosphate compound to form a titanium composite, and the composite is further hydrothermally treated to modify the coating layer. This is a method for producing titanium composite materials characterized by The purpose is to modify the top layer and the top layer, such as improving the

The present invention will be explained in more detail below.

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

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 the affinity with the calcium phosphate compound etc. described below. Accordingly, the surface may be roughened by blasting and/or etching treatment to improve affinity with calcium phosphate compounds, etc., which will be described later, and also to perform activation. 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 addition, in the present invention, titanium and/or tin and/or
Alternatively, these compounds may be included in the hydrochloric acid or nitric acid aqueous solution. This titanium, tin, or a compound thereof may be an elemental metal or a chemical compound, as long as titanium oxide or tin oxide is produced by dissolving it in hydrochloric acid or nitric acid and heating and baking it. Examples include inorganic salts including halogen compounds such as titanium, titanium chloride, stannous chloride, and stannic chloride, organic salts such as tin oxalate, and organometallic compounds such as n-butyl titanate and alkoxytin. Titanium oxide and tin oxide themselves are also included.

In the present invention, a solution in which a calcium phosphate compound or the like is dissolved is applied onto the base material, and then the vaginal compound is heated and precipitated from the solution. Therefore, no matter what shape the base material is, for example, a porous material, the surface A uniform coating can be formed over the entire surface. The reason for using an aqueous solution of hydrochloric acid or nitric acid to dissolve the calcium phosphate compound is that it not only facilitates the dissolution of the calcium phosphate compound, but also allows part of the titanium or titanium alloy of the base material to be dissolved during heating and baking, resulting in the dissolution of the calcium phosphate compound. This is because it can form chemical bonds with compounds and the like to form a calcium phosphate coating with 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
C. If the temperature is lower than 200.degree. C., heating and baking will not be performed sufficiently, and adhesion resistance to the base material will not be sufficiently achieved. 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 calcium phosphate compound underlayer to the base material deteriorates. In addition, if titanium or tin or their compounds are dissolved in the hydrochloric acid or nitric acid aqueous solution,
Titanium oxide and/or tin oxide are precipitated as a base layer along with calcium phosphate compounds, but if titanium oxide or tin oxide is included in the base layer, these will form an extremely strong bond with the base material titanium or titanium alloy. This strengthens the bond between the base material and the underlayer. Furthermore, since titanium oxide and tin oxide are chemically extremely stable and do not undergo chemical changes in living organisms, toxic substances will not be eluted and the underlying layer will not become brittle. The amount of titanium oxide and/or tin oxide to be included in the underlayer can be selected as appropriate, but is preferably 80% or less by weight.

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 or the like. 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 is preferably 300°C to 900°C.

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. When the temperature is high, tricalcium phosphate becomes dominant, and when the temperature is relatively low, hydroxyapatite becomes dominant.

One of the reasons for using a suspension to form a coating layer is to provide unevenness to the surface of the coating layer to increase 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 having a uniform and strong affinity is formed on the base layer, 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 base layer and a coating layer. It forms a strong calcium phosphate compound with a strong bond between the
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.

Through the above steps, it is possible to produce a titanium base material coated with a calcium phosphate compound that is compatible with living organisms, but the calcium phosphate compound in the coating layer formed by heating and sintering has low crystallinity or is nearly amorphous. . In the present invention, hydrothermal treatment is performed to improve crystallinity and increase strength, as well as to further improve compatibility with living organisms.

Hydrothermal treatment refers to a crystal growth method performed in the presence of high-temperature water, particularly high-temperature and high-pressure water.

The conditions for the hydrothermal treatment are not particularly limited, but in the presence of steam in an autoclave, from 100°C to 200°C (pressure is approximately 1°C).
~16 kg/cm''), which improves the crystallinity of the coating layer.

During this hydrothermal treatment, a portion of tricalcium phosphate is converted into hydroxyapatite.

In addition, in general, to produce hydroxyapatite crystals, 40
The process is carried out at a temperature of 0°C to 500°C, but since the purpose of the present invention is to improve the stability by improving the crystallinity of the coating layer, the process can be carried out under the relatively mild conditions mentioned above, and the process can be carried out at a higher temperature. do not have to. Of course, without considering economic efficiency20
Processing may be carried out at temperatures exceeding 0° C., and the quality of the product will not deteriorate in this case either.

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

Application Example 1 Calcium hydrogen phosphate (CallPO4) was dissolved in a 20% nitric acid aqueous solution to prepare a coating solution of a calcium phosphate compound containing 10% calcium hydrogen phosphate.

Length 10c II + x Width 10c + ax Thickness 31 pieces J [S1
The surface of the grade titanium material 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.

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 coated on the titanium oxide having this tricalcium phosphate underlayer. 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. When the crystalline phase of this coating layer was diffracted using X-rays, it was found that the crystalline phase was tricalcium phosphate with low crystallinity, that is, almost amorphous.

The titanium base material on which this composite layer was formed was placed in a stainless steel autoclave with pure water, and hydrothermal treatment was performed at each temperature shown in Table 1 for a certain period of time. The results are shown in Table 1.

As shown in Table 1, there was no change when treated at 90°C, crystal growth occurred at temperatures above 100°C, and conversion of tricalcium phosphate to hydroxyapatite was observed at higher temperatures.

Example 2 A coating solution was prepared by dissolving dibasic calcium hydrogen phosphate having a calcium content of 5 g/l in an aqueous hydrochloric acid solution of titanium chloride containing a titanium content of 5 g/Il.

After blasting the same titanium material as in Example 1,
It was degreased with acetone and pickled with a 20% aqueous hydrochloric acid solution at 60° C. to remove the surface deposits to obtain a titanium base material.

The coating solution was applied to the titanium substrate, dried at 80° C. for 15 minutes, and then fired in flowing air at 500° C. for 15 minutes. This operation was repeated four times to form a strong base layer coating of the titanium oxide-tricalcium phosphate mixture having a thickness of about 1 to 2 .mu.m.

A suspension of calcium phosphate compound was applied to this, and 8
After drying at 0°C for 1 hour, it was heated and sintered at 800°C for 2 hours in an argon atmosphere. The suspension contains 10% calcium hydroxide.
Dissolved in nitric acid aqueous solution and added Ca 2+ ions to it as PO
Calcium hydrogen phosphate was added so that the molar ratio with 43-ion was 3:2, and the same tricalcium phosphate powder as in Example 1 was further added.

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.

When this coated titanium plate was hydrothermally treated at 180°C for 3 hours in the presence of water vapor in an autoclave, most of the calcium phosphate compound in the coating layer was converted to hydroxyapatite, resulting in a titanium plate having a hydroxyapatite coating with good crystallinity. I was able to get it.

The urethane foam is impregnated with a suspension of fine titanium particles and sintered in an inert atmosphere to achieve a porosity of 90-95.
% three-dimensional reticular titanium was obtained.

Using this as a base material, etching was performed in a 15% hydrochloric acid aqueous solution at 80° C. to activate the surface, and a base layer and a coating layer of a calcium phosphate compound were formed on the surface under the same conditions as in Example 1. However, since the brush method was insufficient for applying the coating solution, immersion in the solution was used. As a result, it was possible to obtain a three-dimensional reticulated titanium composite material having a composite coating consisting of a base layer and a coating layer of a calcium phosphate compound having a thickness of about 50 μm evenly over the entire surface.

This composite material was placed in a stainless steel autoclave and hydrothermally treated at 150° C. for 4 hours.

Through this treatment, the nearly amorphous calcium phosphate compound became a mixture of hydroxyapatite and tricalcium phosphate with relatively good crystallinity.

(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, it is a composite coating in which a base layer of a calcium phosphate compound or the like is first formed on the surface of the base material by heating and sintering, and then a covering layer is formed on top of that by heating and sintering. The affinity between each of them is very large, and the overall strength is high because the surface layer is a layer formed by heating and sintering with high strength.

Fourthly, when forming the base layer, a solution such as a calcium phosphate compound is applied to the base material and the calcium phosphate compound etc. is precipitated from the solution, so that it can be applied uniformly over the entire surface of any shape of the base material. Furthermore, the yield of the calcium phosphate compound is good, and the condition of the coating can be easily controlled to form a high-quality coating.

Fifth, since the coating layer of the calcium phosphate compound, which is formed by heating and sintering and has relatively poor crystallinity, is hydrothermally treated to improve its crystallinity, the strength of the coating layer itself is enhanced, and it is This improves the affinity of the material and dramatically improves its function as a bioimplant material.

Claims (3)

[Claims] (1) Activate the surface of a titanium or titanium alloy base material, apply an aqueous solution of hydrochloric acid or nitric acid in which a calcium phosphate compound is mainly dissolved, and heat and bake it to coat the base material with a base material containing a calcium phosphate compound. A titanium composite material is formed by forming a geological layer, then applying a suspension of a calcium phosphate compound thereon and heating and sintering it to form a coating layer of a calcium phosphate compound, and then hydrothermally treating the composite material to form a coating layer of the calcium phosphate compound. A method for producing a titanium composite material, comprising modifying a coating layer. (2) The manufacturing method according to claim (1), wherein the hydrochloric acid or nitric acid aqueous solution is one in which titanium and/or tin and/or their compounds are dissolved in addition to the calcium phosphate compound. (3) The manufacturing method according to claim (1), wherein the hydrothermal treatment is performed in steam at 100 to 200°C.