JPH01146558A - Preparation of tricalcium phosphate coat - Google Patents

Abstract

PURPOSE:To form an autermost surface layer of tricalcium phosphate, which can be firmly and strongly bonded to a metal, on the surface of a base in simple process, by coating the base with the flame spray of powder mainly composed of specific calcium phosphate. CONSTITUTION:A base is coated with the flame spray of powders mainly composed of a calcium compound and a phosphate, and the coat is then processed to be converted to a layer of tricalcium phosphate. The molar ratio of Ca/P of the powders used is 2 or lower, but is preferably at about 1.5 or less; for example, the calcium compound is CaO, Ca(OH)2, CaCO3 and the phosphate CaHPO4, Ca2P2O7, Ca4(PO4)2O, (NH4)3PO4, Ca3(PO4)2. The base may be made of metal, ceramics, glass or plastics, depending upon uses. The coated base is soaked in cold or hot water for some hours or is exposed in a steam atmosphere of a high pressure and a high temperature, thus allowing the coat to be converted to a layer of calcium phosphate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a manufacturing method for forming a tricalcium phosphate coating on a core material as an implant.

In recent years, implants used for artificial joints, artificial bones, artificial tooth roots, etc. have been sought to have greater biocompatibility and higher mechanical strength.As a result, hydroxyapatite, which has excellent biocompatibility, has been By thermally spraying a calcium phosphate compound containing a metal material onto a core material made of a metal material, an implant having excellent biocompatibility on the outside and mechanical strength has been provided.

However, in the past, when hydroxyapatite powder was thermally sprayed, the hydroxyapatite decomposed due to thermal metamorphosis, resulting in a decrease in its affinity for living organisms, making it extremely difficult to use. It cannot be said to be highly sexual.

In view of the above, the present inventors have conducted intensive research based on the possibility that tricalcium phosphate can be a substitute for hydroxyapatite, and have found that a powder containing mainly calcium phosphate, which is the starting material for tricalcium phosphate, has been developed. By thermal spray coating and further converting it into tricalcium phosphate, it is possible to form a tricalcium phosphate thermal sprayed layer on the outermost layer that has a stronger and more reliable bonding force with metal while shortening the manufacturing process. The present invention was developed based on this knowledge.

Hereinafter, the composition of the starting materials of the present invention and Examples will be described in detail.

The material composition in the present invention is the starting material Ca/P.
It is a powder containing a calcium phosphate with a molar ratio of 2 or less, preferably 1.5 or less, or around 1.5, and the calcium is Cab, Ca(OH)t. , CaCO3, phosphate is campoa, catptot, ca*(po+)to
.

(NH4)3PO4, Ca5(Po4)z, etc. may be exemplified.

Further, the base material for thermal spray coating is appropriately selected depending on the intended use, such as metal, ceramics, glass, or plastic.

Also, the process for converting it to tricalcium phosphate is
The coated substrate is immersed in water or hot water for several hours.

Alternatively, it is immersed in a steam atmosphere with high temperature and pressure.

Alternatively, immersion in phosphate or the like is exemplified. More specifically, immersion in a steam atmosphere at 120° C. and 2.2 atm for about 2 hours is exemplified.

Examples The method for forming tricalcium phosphate thermal spraying sheets from these material compositions is as follows: (1) A mixed material with a Ca/P molar ratio set within the above range, a compound such as pulscheite, or a pre-generated phosphorus Tricalcium acid powder is sprayed onto the surface of the substrate using high temperature plasma.

That is, the reaction of the material whose Ca/P molar ratio is set within the range described above proceeds in high-temperature plasma, and the mixed material powder is injected together with the high-temperature plasma by a plasma spray gun, and is collided with the metal surface. do. The heat and collision force of this high-temperature plasma not only accelerate the synthesis reaction to tricalcium phosphate as much as possible, but also form a pre-sintered housing using this energy. The plasma atmosphere at this time is sufficient because argon, helium, hydrogen, and nitrogen rings are generally used, and the gas ratio of the atmosphere is as follows:
For example, H, /Ar are mixed in a ratio of O~25/60~150, and a plasma spray gun (Meteco 9
When using MB), the current is 300 to 500 (A),
It supplies electric power with a voltage of 50 to 8 o(v).

As described above, the thermal spray coating method of the present invention can be easily carried out using a commonly used plasma spray gun, etc., and can not only produce an implant with high adhesive strength, but also Since calcium is generated during the thermal spraying process, the manufacturing process can be significantly shortened, and the effects are tremendous.

Note that tricalcium phosphate has the characteristic that it can actively change into hydroxyapatite over time, but Ca/
Since the range of P molar ratio is wider than that, the coating layer formed by plasma coating is not uniform although it undergoes thermal transformation, but tricalcium phosphate accounts for the majority.

Hereinafter, the present invention will be explained in detail using experimental examples.

Experimental Example I A mixed powder of CaHPO, 82HtO, and CaCO3 was thermally sprayed onto a flat plate (SUS316) that had been sandblasted with an alumina grid using the plasma gun described above. A coating layer having a thickness of about 50 μm was formed.

When this coating layer was identified by powder X-ray diffraction, the formation of tricalcium phosphate was indeed observed.

Experimental Example 2 A mixed powder was produced by adding tricalcium phosphate powder having a particle size of 20 to 40 μm, which was synthesized by a wet method and spray-dried to the same mixed powder as in Experimental Example 1. Next, apply this mixed powder to the surface of the artificial bone (SUS316L).
Nitrogen gas is 100. Current and voltage values are 500 (A),
Thermal spray coating was performed using the plasma gun set at 80 (V). - As a result of identifying the coating layer by X-ray diffraction method, it was found that the surface layer was tricalcium phosphate.

Experimental Example 3 Using Prushite (CaHPO42HtO) powder as the starting material, plasma coating (using N gas) was applied to the surface of the base material (titanium) in the same manner as above to form a coating layer.

When this coating layer was analyzed by X-ray diffraction, it was confirmed that it had been transformed into tricalcium phosphate.

An implant manufactured in the same manner as in Animal Experiment Example 3 was implanted into the lower limb bone of an adult dog and observed over time. As a result, no abnormal findings such as inflammatory reactions or shedding of the sprayed coating layer were observed even 3 months after implantation. It wasn't something.

Patent applicant Advance Co., Ltd.

Claims (1)

[Claims] (1) Triphosphate, characterized in that the surface of the base material is thermally spray coated with a powder mainly composed of calcium and phosphate with a Ca/P molar ratio set to 2 or less, preferably around 1.5 or less. Method for producing calcium coating material.