JPS59111753A - Artificial medical material and use thereof - 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 (a) Technical Field The present invention particularly relates to artificial bones, artificial medical materials used for bone shaping and fixation, alveolar bone implants, and the like.

(b) Background of the Technology Various metal materials have been used in the past, mainly in the field of orthopedics, but the most important issues are compatibility with living organisms, bondability, corrosion resistance, etc. On the other hand, shape memory alloys have made remarkable progress in recent years. Shape memory alloys remember their shape when held at a certain temperature or higher for a certain period of time, and even if they are deformed into a different shape at a temperature lower than that temperature, they return to the memorized shape when heated to a certain temperature. It has excellent characteristics such as. When considering medical materials that take advantage of this property,
The above-mentioned compatibility as a biomaterial becomes a problem.

There are various shape memory alloys, but currently Ni-
Ti alloy, Cu-Zn-'Aff1 alloy, etc. are mainstream.

When using these as medical materials, the first problem is the toxicity of Ni++ ions and Cu''+ ions to living organisms.

Therefore, shape memory alloys cannot be used as medical materials unless this problem is solved and they are also given affinity and bonding properties with living organisms.

(c) Disclosure of the invention The main points of the present invention are as follows.

Diamond, alumina,
Coating with a substance such as apatite or bioglass prevents the alloy from coming into direct contact with living organisms, and also prevents metal ions from leaching into living organisms. Moreover, since the above-mentioned substances have excellent affinity or bonding properties with living organisms, the coated alloy becomes highly biocompatible. The coating method uses PVD%CVD or sputter league method to achieve particularly excellent adhesion to the alloy surface, and does not inhibit deformation for molding or shape memory, or shape recovery deformation, and during use. The first feature is that it prevents peeling of the thin body from occurring.

In addition, as for the manufacturing process or treatment process, after the above-mentioned coating treatment is applied to an alloy molded body of a predetermined size, it is memorized into a desired shape at high temperature, transformed into a shape that is easy to perform treatment or suitable for the purpose at room temperature, etc., and then applied inside the body. The second feature is that after implantation, the temperature is raised to the shape recovery temperature by some method to restore the memorized shape.

The above-mentioned coating may be a single-phase coating, but if necessary, it may be double-coated with alumina as the first layer and another substance coated on top of it to further improve adhesion. It is a characteristic.

The fourth feature is that apatite is coated by sputtering to provide stable performance in terms of chemical composition and affinity and bonding properties.

NiTi memory alloys are said to be less likely to corrode in living organisms and have good compatibility. However, recent research shows that Ni+
It is becoming clear that + ions are carcinogenic, and the use of NiTi alloys as medical materials must also be considered dangerous.

Furthermore, Cu4+ ions are particularly toxic in Cu-Zn-A1 alloys. Therefore, both alloys cannot be used directly as medical materials due to their toxicity. However, its shape memory properties are very useful. Therefore, the first method is to coat the surface with some kind of substance to prevent direct contact with living organisms. Furthermore, if this coating layer could be made into a material that not only has good corrosion resistance or does not react with living organisms, but also has biocompatibility and binding properties, it would be very possible to use shape memory alloys as medical materials. I think it will be useful.

Therefore, alumina, diamond, apatite, bioglass, etc. are effective as coating materials. Each will be explained below.

Aluminum (A) 203) has good biocompatibility, and polycrystalline alumina and single-bonded alumina (sapphire) are already used as implant bone materials.

Therefore, the above-mentioned objective can be achieved by coating the alloy surface with alumina. Furthermore, it is conceivable that the first layer is made of dense alumina with a thickness of 1 to 10 .mu.m, and then coated with porous alumina having pores of 20 to 150 .mu.m or alumina with a surface of similar roughness. This is because new bone grows in alumina, which is porous or has a high degree of roughness, and it becomes a medical bone material that has a very high bonding property with autologous bone.

Next, apatite (aqueous apatite Ca 10.0.
)6(OH)g) or bioglass that generates apatite on the surface over time in vivo (composition example Ca0-P2
O3-5i02-Na20) is a substance that completely bonds with autologous bone without forming an interfacial film, and furthermore, apatite is replaced by new bone. Originally, bones are made up of 65% apatite, 8
It is natural that synthetic apatite has good bonding properties with bones, as 5% of the body is composed of organic substances, mainly collagen. Therefore, if these substances are coated directly on the surface of the shape memory alloy or coated on an alumina coating layer of 1 to 10 μm to obtain even better adhesion, a bone medical material with excellent bone bonding properties can be obtained. can get.

Furthermore, diamond quality carbon has excellent compatibility with living organisms and is particularly characterized by its lack of antithrombotic properties. Therefore, an alloy of this substance alone or coated with alumina as mentioned above is particularly suitable as a medical material to be implanted into the bloodstream.

Next, the coating method will be described.

PVD is a physical vapor deposition method.
It is an abbreviation for urDeposition, and its origin is vacuum evaporation, in which raw materials are evaporated by resistance heating or electron beam heating in a vacuum and then condensed on a substrate. Since then, sputtering has been used to deposit atoms and clusters ejected from the raw material by ions onto a substrate, ion blating has been used to evaporate and ionize the raw material, and then deposit the atoms and clusters on the substrate by applying a negative voltage, and then changing the atmosphere to a reactive gas. There are various methods, such as reactive vapor deposition, to produce atomized compounds.

CVD is a method of coating by causing a chemical reaction through excitation of heat, plasma, etc. It is essential to obtain a raw material source in the form of a gas, and chlorides and organic metals are used as raw materials for metal elements.

As described above, all of them are techniques for coating the surface of another object with a thin film of a compound or a single substance, and each has the above-mentioned characteristics.

Therefore, as a coating method for alumina, PVD or CVD under the following conditions is suitable for this purpose.

■Alumina coating strip example 02 by PVD method Atmosphere 10'~1O-3Torr, substrate temperature 30
Al2O3 is evaporated with an electron gun under conditions of 0 to 500°C, and plasma is generated and activated by high frequency to generate a voltage of several hundred V.
Al2O3 is coated on the substrate to which a bias of .

■Alumina coating strip example 2A by CVD method CJa +3, CID 2 + 3 H2-A
l2O3+6HCj2+3CO' Substrate temperature: 950°C
The above reaction is carried out at -100°C and a total pressure of 50 to 60 torr.

(2) The diamond coating can be obtained by plasma CVD, and examples of the conditions are as follows.

CnH2n4.2 '-' nC+ (n + 1)
H2 temperature: 600~1000°C 1 pressure crab 10~
A mixed gas of excited hydrocarbon gas and Hz gas (CnH
2n+2/Hz)=0.005~0.2 P70t0
e=1~300torr substrate temperature 600~1000°C
It is generated under the following conditions.

■ Because it is a complex component such as apatite or iodine, it is difficult to coat it with ion blasting or CVD, so sputtering is suitable (for example, under the following conditions). A coating layer with higher adhesion was obtained by sputtering.

Sputtering form: Planar type RF sputtering target: Apatite or ion class itself Atmospheric pressure Ar 10” TorrRF output:
2 W 7cm2 Substrate bias: 50■ Next, I will explain one reason for limiting the thickness of the coating layer.

The purpose of using alumina as a base coating (alloy and secondary
It provides strong adhesion between the layer coating and
The goal is to completely seal the surface of the alloy. If the thickness is less than 1 .mu.m, there is a problem in sealing performance due to pinhole ν, etc., and it is meaningless for the above-mentioned purpose to increase the thickness by 10 .mu.m or more, so a thickness of 1 to 10 .mu.m is sufficient.

When covering this base dense alumina layer with a thick alumina layer, etc., it is necessary to have at least half the thickness, but if it is too thick, the coating alloy itself may deform. Since peeling may occur, the maximum thickness is preferably 100 μm or less.

In addition, apatite needs to be thick due to its characteristics (because it is thin, so if it is a single layer, it is necessary to make a seal), so a thickness of 5 to 10 μm is sufficient.
m is fine.

Furthermore, since a diamond coating has a very dense deposited layer, a coating of 1 to 2 .mu.m is sufficient even in the case of a single layer or a composite layer.

The above thickness was determined based on the sealing properties of the alloy surface, the compatibility with living organisms, the absence of peeling of the coating layer due to deformation of the coating alloy body, and economic efficiency.

Next, the manufacturing process will be described.

After processing the alloy to a predetermined size, it is coated and then shape memory learning is performed at a high temperature, e.g. 300° in the case of NiTi alloys.
The temperature is between 500°C and 500°C. It is then cooled, deformed into any shape suitable for the treatment, implanted, heated to a temperature above the memory recovery point, and returned to the memorized shape to achieve the intended purpose.

In particular, the reason why the memory learning is performed after the first-stage coating process is as follows. In other words, with PVD%CVD, the material reaches a high temperature (usually 700°C to 1000"C) and its previous memory disappears.Also, although it is theoretically possible to memorize the shape during this process, This is because if the temperature is too high, the stress of the material during recovery will be small, and the mechanical force will be small, making it difficult to put it into practical use.Therefore, the shape memory learning process was applied after the coating process.The problem at this time is that the coating layer and It is the adhesion (adhesion) strength with the alloy and its thickness.

For this reason, the coating method and coating thickness are limited as described above.

Next, examples will be shown.

As an example shape memory alloy, Ni has a memory recovery temperature of about 50°C.
A bone plate 1 for fixing a fractured part as shown in FIG. 1 was prepared using a Ti (Ni:Ti=1:1) alloy.

This surface is first coated with alumina with a thickness of about 5 μm, and then porous alumina with a pore size of about 60 μm is coated on top of it with a thickness of 4.0 μm and a thickness of about 8 μm.
Apatite coatings with a thickness of about 1.5 μm and diamond coatings with a thickness of about 1.5 μm were prepared.

The conditions of the coating process are approximately the same as those shown in the example above. Both ends of such an object were chucked and the object was kept at 4.50°C for 15 minutes while applying 3% tensile deformation in the longitudinal direction to memorize the shape. Thereafter, it was similarly deformed at room temperature into a shape with an additional 5% elongation. .

This bone plate was used for femur fracture surgery in dogs. That is, as shown in Fig. 2, after fixing the bone plate l to the fractured bone 3 using fixing pins 4,
Heated to 5°C. The bone plate tried to return to its memorized shape (in this case, it tried to shrink), ensuring that the ends of the fracture came into contact with each other and exerting an effective force for bone repair.

Six months after the surgery, the surgical site was observed, and it was found that the bonding was completed more quickly and completely than with the conventional stainless steel pawn plate, and that the bone plate with porous alumina and apatite coating on the outermost surface was New bone had been generated in the area where the plate had joined, and there was no corrosion or other changes in other areas, indicating that the plate could be left in place as is.

In addition, in the diamond-coated specimen, only a very thin interface was formed at the interface with the living body, and no other changes were observed.

[Brief explanation of drawings]

FIG. 1 is a bone plate according to an embodiment of the present invention. FIG. 2 is a front view when fixing a fractured part. ■, : bone plate, 2: hole, 3: bone, 4: bottle 71
11D Hou 2 Procedural Amendment Written on 70/2/1981 1. Indication of the case 1982 Patent Application No. 220771 2. Title of the invention Artificial medical drug and its method of use 3. Person making the amendment Relationship with the case Patent applicant address: 5-15 Kitahama, Higashi-ku, Osaka Name (21
3) President of Sumitomo Electric Industries, Ltd., Tetsube 4, Agent address: 6, Sumitomo Electric Industries, Ltd., 1-1-3 Shimaya, Konohana-ku, Osaka, Column 7 for detailed explanation of the invention in the specification subject to amendment , Details of the amendment (1) In the second line of page 4 of the specification box, "sputter league" is corrected to "sputtering." (2) On the 5th stroke of the same page in the same book, ``Shobo ni'' is deleted. (3) In the same book, page 7, line 6, ``on'' is corrected to ``1 on''. (4) On the same page, line 13 of the same book, ``since ion'' has been corrected to ``in addition to the electron gun,'' and ``knocked out'' has been corrected to ``1 was melted and evaporated.'' (5) From lines 14 to 15 on the same page of the same book, delete ``evaporate --- onto the substrate''. (6) In line 5 of page I of the same book, ``after'' is corrected to ``let''. (7) In the fifth line from the bottom of the same page of the same book, ``ng, furthermore'' is corrected to ``blowfish law, furthermore that''. (8) In the fourth line from the bottom of the same page of the same book, ``reactive evaporation'' is corrected to ``reactive ion blating, which introduces a reactive gas into the substrate and forms and coats the substrate with a compound.'' (9) In the third line from the bottom of the same page in the same book, "There is a method." ” is corrected. Width 00) Dokan page 9, 6 lines, 1PTotceJ as ``Ptotal!JIC revised IE.

Claims (1)

[Claims] (1) Diamond, alumina, on the surface of the shape memory alloy,
An artificial medical material characterized by being tightly coated with a single layer or a composite layer of a material having affinity with living organisms or having excellent bonding properties, such as apatite or bioglass, by a method such as PVD, CVD, or sputtering. (2. In claim (1), the coating layer on the surface of the memory alloy has a first layer of alumina of 1 μm to 10 μm, and a second layer thereon of apatite of 0.5 to IO μm or 1 to 2 μm. (3) An artificial medical material characterized in that the second layer of apatite in claim (2) is a layer coated with a diamond thin film. Material. (4) In a method of using a shape memory alloy as an artificial medical material, diamond, alumina,
Substances that are compatible with living organisms or have excellent bonding properties, such as apatite or bioglass, are coated in a single layer or in multiple layers by methods such as PVD, CVD, or sputtering, and then subjected to shape memory learning at high temperatures before being applied to a specified area. A method of using an artificial medical material, which is characterized by implanting it into the body as a shape and restoring it to a memorized shape by increasing temperature.