JP4423423B2 - Calcium phosphate compound-coated composite and method for producing the same - Google Patents

Description

  The present invention mainly relates to calcium phosphate compound-coated composites used in orthopedics, dentistry, etc. as medical biomaterials such as implant materials such as artificial bones, teeth and roots, joint materials thereof, fracture fixing materials, and artificial joint materials. The present invention relates to a material and a manufacturing method thereof.

  Implant materials such as artificial bones, teeth, roots, etc. can be used in a form close to the natural one by joining to the remaining bone or implanting in the jaw bone when the bone or tooth is missing, so the aging progresses In particular, the importance is increasing for health maintenance and cultural life maintenance. Since the implant material is embedded in a living body such as a human body, it is indispensable to be harmless. Affinity to the living body, strength, workability, moderate specific gravity, non-eluting property, and in some cases, Ca ions, etc. Therefore, moderate solubility and the like are also required.

  Implant materials conventionally used in the medical materials field include metals such as α-alumina, precious metals, alloys such as stainless steel, apatite ceramics, etc., but these metals are all incompatible with living organisms. Apatite ceramics are mainly composed of a calcium phosphate compound and have a very good affinity with bones and teeth, but are not sufficient in terms of strength and workability, and their uses are limited.

  Implant materials used in recent years in the dental field can be roughly divided into two. First, a pure titanium material or the like is machined or surface blasted. Second, titanium or the like is used as a metal base and the surface thereof is coated with a calcium phosphate compound.

  Metal materials such as pure titanium are bio-inert materials, and when planted in the jawbone, the surface is not charged, so no bone is added to the material interface at the initial stage. Bone adhesion occurs while bone is added from the surrounding bone to the bone interface (bone conduction bone conduction). However, once bone adhesion occurs, bone resorption by osteoclasts occurs (bone remodeling phenomenon, remodeling), the binding force gradually decreases, and long-term maintenance is difficult.

A calcium phosphate compound, mainly coated with hydroxyapatite Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ (hereinafter referred to as HA), is a bio-active material, which is HA-coated on the titanium interface and within the jawbone. When the plant is implanted, bone conduction occurs at the bone interface on the host side, and bone induction by bone-forming cells occurs at the charged HA interface. The HA interface and the bone interface are ion-bonded by the HA crystal. Cause bone union. However, even when bone fusion occurs in this way, bone resorption by osteoclasts occurs (bone remodeling phenomenon, remodeling), and HA is also absorbed at the same time. It will be in the state of adhesion, and the bone bonding ability will decrease in the long term.

  Here, as a method of forming the calcium phosphate compound layer, a plasma spraying method, a sputtering method, and a thermal decomposition method are known. Among them, when a plasma spraying method (20000 ° C.) is used, a thickness of 30 μm to 50 μm can be obtained, but the bonding strength to the substrate is weak, cracking and peeling are likely to occur, and absorption is easily received. Further, when the base material has a complicated shape or is porous, it is difficult or impossible to cover the entire surface. When the sputtering method is used, the film thickness is limited to about 1 μm, and an arbitrary film thickness corresponding to the application cannot be obtained.

  The thermal decomposition method refers to a method of making ceramics or the like by burning an organic material as a raw material. For example, a method of forming a base layer of a calcium phosphate compound by heating and firing from a nitric acid aqueous solution or a hydrochloric acid aqueous solution of a calcium phosphate compound on a metal substrate, and forming a coating layer of the calcium phosphate compound thereon by heating and sintering the suspension This has made it possible to obtain a composite material in which a calcium phosphate compound coating layer is uniformly formed on the surface of a substrate having an arbitrary shape (Patent Document 1). However, since the thickness of the coating layer by this pyrolysis method is about 5 μm, it is absorbed in 1 to 2 years. In addition, since the calcium phosphate compound is directly deposited on the surface of the base material from the aqueous solution, the adhesion between the calcium phosphate compound coating layer and the base material becomes insufficient, and absorption and peeling are likely to occur when used over a long period of time. .

  As described above, when the calcium phosphate compound is directly coated on the base material, the adhesive strength is lowered. Therefore, it has been studied to use calcium titanate as a lower layer binder. However, a well-known method for preparing calcium titanate is a dry method in which sintering is performed at 1200 ° C., and only coarse powder having a particle diameter of about 3 to 5 μm can be obtained. In other words, the calcium titanate produced by this method cannot be formed into a film, and therefore cannot be used as a lower layer binder. Further, the high temperature of 1200 ° C. causes deterioration of the metal base material. Active and weak in bone formation.

  For this reason, as an implant material used in the dental field, a material that enables single planting is ideal, and in a situation where an occlusal force is applied, the interface to the living bone is maintained in a bioactive state for more than 10 years, and bone bonding The development of functionally gradient materials that maintain the strength (bone adhesion) is a challenge.

  On the other hand, in the orthopedic region, stainless steel or titanium alloy having good workability is used for fracture fixing materials, artificial joints, and intraosseous fixing materials (screws and plates). The artificial joint needs to be maintained in the living body for more than 10 years. On the other hand, the intraosseous fixation material used at the time of fracture needs to be bioactive and strongly bone-bonded for a certain period of time required for healing, and to be easily removed after the healing because the bone-binding ability is lowered.

  However, in the current metal materials, cations are eluted in vivo and proteins are adsorbed, resulting in not only tissue damage as a foreign body reaction, but also fibrous tissue is increased at the interface, and the bone binding ability is remarkably lowered. In some cases, a coating is applied with a calcium phosphate compound. However, as described above, peeling and resorption occur, and the bone binding ability decreases.

  For this reason, in the orthopedic field, it is necessary to develop a multifunctional covering material that can be maintained in the living body for more than 10 years, but can adjust the elution of Ca ions so that it can be easily removed at any time. It has become.

In addition, regardless of orthopedics or dentistry, when a calcium phosphate compound coating material is implanted in a living bone, it generally causes cuts, inflammation, etc. due to surgical treatment, the tissue fluid becomes acidic, and the calcium phosphate compound layer dissolves temporarily. Rather than using calcium phosphate compounds alone, the development of new functionally graded materials combined with bioactive materials (interface is (-) charged) that has a slower absorption rate than calcium phosphate compounds and that keeps Ca eluted is an issue. ing.
JP 62-221359 A

  In view of the above problems, the present invention is a calcium phosphate compound coating material that can be used as an implant material for artificial bones, teeth, roots, and the like, wherein the metal substrate and the calcium phosphate compound layer are firmly bonded and are absorbed by the host. Another object of the present invention is to provide a functionally gradient material that constantly releases Ca for a certain period of time and activates osteogenic cells.

  In order to solve the above problems, the present invention provides a calcium titanate / amorphous carbon composite layer by interposing a calcium titanate / amorphous carbon composite layer between a metal substrate and a calcium phosphate compound layer. As a bonding material, a metal base material and a calcium phosphate compound are firmly bonded to suppress peeling, and a functionally gradient material capable of forming bone during a desired period while receiving absorption by a host is realized.

That is, the calcium phosphate compound-coated composite material of the present invention is obtained by applying an organic solvent solution containing titanium and calcium in a range where the Ca / Ti ratio is 1.01 to 1.10. It is characterized in that a calcium phosphate compound layer is formed through a calcium titanate / amorphous carbon composite layer provided by heating at 500 to 650 ° C. and firing at 500 to 650 ° C.

In addition, the method for producing a calcium phosphate compound-coated composite material of the present invention includes titanium and calcium in a range in which the Ca / Ti ratio is 1.01 to 1.10 on the metal substrate prior to the formation of the calcium phosphate compound layer. It is characterized by forming a calcium titanate / amorphous carbon composite layer by applying an organic solvent solution as a coating solution, raising the temperature at 20 to 200 ° C./min, and heating and firing at 500 to 650 ° C. And

The coating solution may be a solution in which an organic or inorganic calcium compound and an organic titanium compound are dissolved in an organic solvent. The calcium phosphate compound layer can be formed by applying an organic solvent solution containing phosphorus and calcium as a coating solution and heating and firing at 500 to 650 ° C. An organic solvent solution containing phosphorus and calcium in a range where the Ca / P ratio is 1.75 to 1.85 can be used. This thermal decomposition method is not necessarily required as long as the function of the calcium titanate / amorphous carbon composite layer is not impaired, but it is convenient because it is the same route as the calcium titanate / amorphous carbon composite layer.

The coating solution may be a solution in which an organic or inorganic calcium compound and an organic phosphorus compound are dissolved in an organic solvent.
In the present invention, the calcium phosphate compound constituting the calcium phosphate compound layer mainly hydroxyapatite _{(Ca 10 (PO 4) 6} (OH) 2) refers to.

The calcium titanate / amorphous carbon composite composing the calcium titanate / amorphous carbon composite layer is one synthesized by the above-described method. This synthetic product is higher in strength and has an insulating property than calcium titanate obtained by a well-known calcium titanate synthesis method, that is, a dry method in which a mixed powder of calcium carbonate and titanium dioxide is heated at 1200 ° C. Although it is the same, the crystallinity is good, it can be formed into a film shape, and the properties are very different in that it does not dissolve easily in vivo. As a composite of calcium titanate and amorphous carbon Presumed to exist. This calcium titanate / amorphous carbon composite is easily compatible with metals such as titanium and titanium alloys, has high adhesion to metals and is less likely to peel off, and can be formed into a film as described above. It can be used as a metal coating material and function as a lower layer binder (adhesive) or a metal protective film.

  The result of elemental analysis (TEM-EDX) of synthetic calcium titanate is shown in FIG. (A) in the figure is a synthetic calcium titanate / amorphous carbon composite by the above-mentioned method (pyrolysis method, heated at 650 ° C.), and (b) is a synthetic calcium titanate by a dry method (heated at 1200 ° C.). It is.

FIG. 2 shows a model structure of a synthetic calcium titanate / amorphous carbon composite by the above-described method. In the composite, as shown in (a), calcium titanate is an oxide having the same crystal structure as that of the natural mineral CaTiO ₃ , that is, a perovskite oxide (generally expressed as ABO ₃ ). As shown in (b), the amorphous carbon is considered to exist as precipitation into the crystal lattice, substitution into the crystal lattice, substitution, and precipitation into the lattice defect portion as shown in (b). When such a calcium phosphate compound layer is formed using such a calcium titanate / amorphous carbon composite layer as an underlayer, almost only hydroxyapatite is formed, and high bone bonding ability is exhibited.

  As the metal substrate, a metal or alloy selected from titanium, titanium alloy, stainless steel, and cobalt-chromium alloy that is stable in vivo is preferably used. Here, titanium or a titanium alloy means a titanium alloy to which Ta, Nb, Zr, platinum group metal, Al, V or the like is added in addition to metal titanium, and stainless steel means so-called stainless steel such as SUS304, SUS310, and SUS316. Steel is referred to as a cobalt-chromium alloy, which refers to a corrosion-resistant alloy such as a cobalt-chromium alloy for living body implantation. It may have a plate-like shape, a rod-like shape, a smooth surface, a sponge-like porous surface, or an expanded mesh or a porous plate. Such a metal substrate has sufficiently large mechanical strength and is easy to work as compared with a sintered body or glass. In order to improve the affinity with the above-mentioned calcium titanate / amorphous carbon composite and to activate it, the surface of the metal substrate is previously washed with water, pickled, ultrasonic washed, steam washed, etc. It is desirable to purify and to roughen the surface by blasting and / or etching if necessary. Etching may be any of chemical methods, physical methods such as argon etching, and sputtering.

An organic or inorganic calcium compound is used as a Ca source, and is a metal soap that is chemically stable and soluble in an organic solvent, such as calcium salts of carboxylic acids such as naphthenic acid, 2-ethylhexanoic acid, and stearic acid. Can be used. Of these, a calcium salt of 2-ethylhexanoic acid, which has a certain chemical composition and has a relatively low molecular weight, can increase the calcium content, is particularly preferable. 2-ethylhexanoic acid can contain about 12% calcium, but in order to remove carbon dioxide dissolved in the coating solution and leave amorphous carbon, Since it is necessary to leave unreacted 2-ethylhexanoic acid, calcium 2-ethylhexanoate containing 5-8% calcium is preferable. A commercially available metal soap may be used as it is, or may be prepared by a reaction between a carboxylic acid and an inorganic calcium compound such as calcium oxide. For example, calcium nitrate can be used as the inorganic calcium compound. Commercial products of calcium 2-ethylhexanoate contain 4.5-5.5% calcium.

The organic titanium compound is used as a Ti source and a C source, and a titanium alkoxide that is chemically stable and soluble in an organic solvent, such as titanium tetraisopropoxide, can be preferably used.
Examples of organic phosphorus compounds include phosphate esters that are chemically stable and soluble in organic solvents, such as trimethyl phosphate, tri-n-butyl phosphate, tricresyl phosphate, tri (2-ethylhexyl phosphate, di-phosphate). n-butyl, di (2-ethylhexyl) phosphate, bis (2-ethylhexanoic acid) hydrogen phosphate, etc. can be used, and in order to remove carbon dioxide dissolved in the solution, bis (hydrogen phosphate) It is preferable that a part or all of a phosphoric acid di- or monoester such as 2-ethylhexyl is contained to make it acidic.

  As the solvent, it is necessary that the above compound can be stably dissolved, and that the carbon titanate can be stably held in the amorphous (amorphous) state by calcium titanate, and mutual with added water. Since it is preferable that the solvent can be dissolved and the solute concentration and viscosity can be adjusted, the following organic solvents, 2-propanol (isopropyl alcohol), 1-butanol (n-butanol), 1-pentanol (n -Amyl alcohol), alcohols such as ethylene glycol, or mixtures thereof are preferably used. This is because the addition of water requires a hydroxyl source for the formation of hydroxyapatite. If the moisture is low, β-TCP (tricalcium phosphate) is more than half generated.

  As the coating method, conventionally known methods such as dip coating (lifting method), spin coating (rotating method, centrifugal method), spraying method, brush coating and electrostatic coating can be used. It is also possible to add a thickener such as acetylcellulose or ethylcellulose to the coating solution and apply it by a printing method or a transfer method. Among them, dip coating is preferable because it can form a film even on a substrate having a complicated shape, and can also be used for artificial tooth roots and the like. In addition, it is convenient because it does not require a special device and can be manually operated.

When a metal base material coated with an organic solvent solution containing titanium Ti and calcium Ca is heated and fired, a target calcium titanate / amorphous carbon composite (hereinafter referred to as CaTiO ₃ -C) layer is formed on the surface. The obtained metal substrate can be obtained. The temperature during the heating and baking is set to 500 ° C. to 650 ° C. If the temperature is lower than 500 ° C., the crystallinity of CaTiO ₃ —C is lowered, and a large amount of calcium carbonate is generated. This is because if the temperature exceeds 650 ° C., the oxidation of the surface of the metal substrate proceeds rapidly, the mechanical properties deteriorate, and the adhesion of CaTiO ₃ —C also deteriorates. In this case, it is important to set the ratio of Ca / Ti to 1.01 to 1.10. Further, it is important to rapidly heat to about 20 to 200 ° C./min. This suppresses the formation of calcium carbonate, and carbon is contained in the calcium titanate in an amorphous (amorphous) state, so that the crystallinity is improved. When heated gradually, calcium carbonate is contained, the crystallinity is poor, and it is easy to dissolve in the living body. When a calcium phosphate compound layer is formed thereon, TCP (tricalcium phosphate) is generated by a solid phase reaction with CaCO _3, and this TCP is highly soluble. Further, cracks are generated due to the volume change during the phase change, and CO ₂ bubbles are also generated. That is, CaTiO ₃ formed by heating gradually is not suitable as an underlayer.

  When a metal base material coated with an organic solvent solution containing phosphorus and calcium is heated and fired, a target calcium phosphate compound layer is formed on the calcium titanate / amorphous carbon composite layer. The temperature at the time of the heating and firing is preferably 500 ° C to 650 ° C. The calcium phosphate compound is sufficiently crystallized at 500 ° C. to 600 ° C., but it is convenient to match the heating and firing temperature of the calcium titanate / amorphous carbon composite described above.

  These heating and firing are preferably performed in an oxidizing atmosphere, and when performed in a non-oxidizing atmosphere, the organic compound is not sufficiently decomposed, and a large amount of carbon dioxide remains, resulting in the formation of calcium carbonate. In order to prevent the formation of calcium carbonate, it is also preferable to remove carbon dioxide in the system as much as possible before heating and / or heating and baking.

  By the above-described method, a uniform calcium titanate / amorphous carbon composite layer and calcium phosphate compound layer can be formed on the entire surface regardless of the shape of the metal substrate, but the thickness is insufficient. In some cases, a desired thickness can be obtained by repeating a coating-firing operation to form a plurality of thin films.

  By repeating the step of forming the calcium titanate / amorphous carbon composite layer and the step of forming the calcium phosphate compound layer a plurality of times, the calcium titanate / amorphous carbon composite layer and the calcium phosphate compound layer are alternated. A multilayer structure formed in a plurality of stages is preferable. In such a multilayer structure, a calcium titanate / amorphous carbon composite layer is sandwiched between two calcium phosphate compound layers, so that when it is used as an implant, bone forming ability at the implant interface is maintained for a long period of time. It becomes possible to make it.

  Since the calcium titanate solution and the calcium phosphate compound solution are almost composed of an organic solvent, they do not have the ability to dissolve calcium titanate, hydroxyapatite, or tricalcium phosphate itself. Therefore, even if the coating and baking operations are repeated, the base layer does not dissolve, and a uniform and strong coating layer can be formed. Further, since no precipitate is formed at room temperature, it can be stored and used stably for a long time.

In the present invention, when the surface of a metal substrate such as titanium is coated with a calcium phosphate compound layer, a calcium titanate / amorphous carbon composite layer is previously formed on the surface of the metal substrate by a thermal decomposition method. As a result, the following effects can be obtained.
(1) Since the calcium titanate / amorphous carbon composite layer is firmly bonded to the metal substrate and the calcium phosphate compound layer, peeling of the calcium phosphate compound layer can be prevented. The adhesion strength is higher than that formed by plasma spraying or the like.
(2) Since titanium, titanium alloy, stainless steel, etc. are used as the base material, when the artificial phosphate or artificial tooth root is coated with the calcium phosphate compound-coated composite material of the present invention, it is harmless, stable and harmful to the living body. There is no possibility of elution, and it is lightweight and has a sufficiently large mechanical strength and is easy to work with.
(3) Since the calcium phosphate compound layer is provided on the surface, the affinity in the living body is sufficiently large, and bonding can be easily performed with sufficient strength.
(4) Since at least the calcium titanate / amorphous carbon composite layer and, in some cases, the calcium phosphate compound layer, are formed by a thermal decomposition method, that is, coating and baking of a coating solution, there are the following advantages.

  By adjusting the concentration with an organic solvent or adjusting the sintering temperature, an arbitrary film thickness can be obtained by one coating-firing. Moreover, desired layer thickness can be obtained by performing application | coating-baking operation in multiple times. In addition, a multilayer structure in which calcium titanate / amorphous carbon composite layers and calcium phosphate compound layers are alternately arranged can be formed, and an ultrathin multilayer structure can be arbitrarily obtained. Such a multilayer composite layer has strong adhesive force, osteoinductive ability, and bone bonding force, and the resorption rate can be adjusted.

  When both the calcium titanate / amorphous carbon layer and the calcium phosphate compound layer are formed by pyrolysis, a common organic solvent is used for the coating solution, and the coating solution preparation method and coating-sintering method are unified. Therefore, the process can be simplified as compared with the case where each layer is formed by a separate route.

  A uniform coating layer can be formed on the entire surface of a substrate of any shape.

Hereinafter, embodiments of the present invention will be described with specific examples.
(Creation of calcium titanate / amorphous carbon composite layer)
High purity calcium carbonate was heated in air at 1,050 ° C. for 2 hours to obtain calcium oxide. 2-ethylhexanoate 29.8g taken to 100m1 Erlenmeyer flask, while heating to 100 to 120 ° C., was added slowly the above calcium oxide powder 3.36 g, was prepared 2-ethylhexanoic acid number calcium solution. After cooling this solution, 48 g of 1-butanol is mixed, and 16.8 g of titanium tetraisopropoxide is further mixed, and the mixture is sufficiently stirred to give a tan, transparent and viscous liquid (specific gravity 0.92) about 110 ml was obtained. This was used as a coating stock solution and diluted with 3-fold amount (mass ratio) of 2-propanol to obtain a calcium titanate coating solution having an appropriate concentration and viscosity.

  A 35 mm square, 0.7 mm thick JIS type 2 titanium plate was subjected to an etching treatment of boiling for 15 minutes in 6N-HCI, washed once with tap water, three times with distilled water, and dried at 60 ° C. . Using this etched titanium plate as a base material, it is immersed in the above-mentioned calcium titanate coating solution for 5 minutes, slowly pulled up vertically, dried at room temperature for 10 minutes, and at 110 ° C. for 20 minutes, and then in air at 650 ° C. Rapid heating and holding at that temperature for 10 minutes followed by rapid cooling. This coating, drying, and firing operations were repeated a total of three times to form a coating layer on the surface of the titanium plate. The coating layer was grayish brown.

FIG. 3 shows the result (X-ray diffraction image) of examining the crystal phase of the titanium plate coating by X-ray diffraction. Along with the α-Ti peak from the titanium plate, a peak of perovskite (CaTiO ₃ ) with good crystallinity is recognized, indicating that a CaTiO ₃ layer is formed. Further, rutile (TiO ₂ ) due to oxidation of the titanium plate is observed. The peak intensity of this TiO ₂ was 1/10 compared to a non-coated material (650 ° C., rapid heating, 30 minutes heating) treated in the same manner except that the calcium titanate coating solution was not applied. It can be seen that the CaTiO ₃ layer suppresses oxidation of titanium. The thickness of the coating layer calculated from the increase in mass compared to the titanium plate and the theoretical density of CaTiO ₃ (4.04 g / cm ³ ) was 0.6 μm. A thin film having a thickness of 0.2 μm is formed by one application-firing. Since the thin film is formed in this way, it is considered that the CaTiO ₃ layer is actually made of CaTiO ₃ —C. Hereinafter, this coating layer is referred to as a three-time coating layer of CaTiO ₃ —C, and a titanium plate coated with the coating layer is referred to as a three-time coating of CaTiO ₃ —C.
(Creation of calcium phosphate compound layer)
In the same manner as described above, a solution of 2-engineered calcium cylohexanoate was prepared, 42 g of 1-butanol was mixed with this solution, and 10.7 g of hydrogen phosphate bis (2-ethylhexyl) and distilled water (OH source) 2 .8 g was mixed and sufficiently stirred to obtain about 100 ml of a clear and viscous liquid (specific gravity 0.89). This was used as a coating stock solution and diluted with 2-propanol (twice amount) (mass ratio) to obtain a calcium phosphate compound coating solution having an appropriate concentration and viscosity. The Ca / P mixing ratio in this coating solution is 1.80, which is higher than the theoretical value of 1.67 for HA. This is because it is desirable to set the Ca / P mixing ratio to 1.75 to 1.85 in order to prevent the formation of β-TCP. Moreover, it is because a part of active ingredient will evaporate.

Next, the three-time coating of CaTiO ₃ —C prepared above is immersed in the above calcium phosphate compound coating solution for 5 minutes, slowly pulled up vertically, dried at room temperature for 10 minutes, and at 110 ° C. for 20 minutes, Rapid heating to 650 ° C. in air, holding at that temperature for 10 minutes, followed by rapid cooling. This coating, drying, and firing operations were repeated 10 times in total to form a further coating layer on the CaTiO ₃ —C coating layer three times.

FIG. 4 shows the result (X-ray diffraction image) of examining the crystal phase of the titanium plate coating by X-ray diffraction. A peak of hydroxyapatite (HA) is observed together with a peak of α-Ti and a peak of perovskite (CaTiO ₃ ) having good crystallinity, and it is confirmed that the coating layer constitutes a HA / CaTiO ₃ -C bilayer. It was. A small amount of rutile (TiO ₂ ) due to oxidation of the titanium plate is also observed. The thickness of the HA layer calculated from the mass increase compared to the three-time coating of CaTiO ₃ —C and the theoretical density of HA (3.16 g / cm ³ ) was 2.4 μm. A thin film of 0.24 μm is formed by one coating-firing.

By repeating the procedure described above, the HA / CaTiO ₃ —C bilayer can be formed in a plurality of stages.
FIG. 5 shows (a) a coating of the present invention in which an HA / CaTiO ₃ —C bilayer is formed, (b) a coating of the present invention in which an HA / CaTiO ₃ —C bilayer is formed in two stages, c) The cross-sectional schematic diagram of each of the conventional HA coatings is shown.

The adhesion strength of the coating layer was examined for the coating of the present invention in which the HA / CaTiO ₃ -C bilayer (only one step) was formed as described above. The test method was based on the paint measurement method (JIS A6909: 2003, architectural finish coating material). The sample was bonded to a steel jig with a two-component epoxy resin (Araldite), and a tensile test was performed. .

The coating of the first example of the present invention in which the HA / CaTiO ₃ —C bilayer was formed measured 4.9 MPa. The surface grain size (Ra) of the etching-treated titanium plate used as the substrate was 2.5 μm with a diamond stylus surface roughness meter. In general, the adhesion strength depends on the surface roughness, and the adhesion strength increases as the surface roughness increases. In the coating of the second example of the present invention in which a HA / CaTiO ₃ —C double layer was similarly formed using a titanium plate (Ra 4.5 μm) blasted with 70th alumina and etched, the adhesion strength was 6. The pressure rose to 7 MPa. On the other hand, in the coating in which the coating layer of only HA is formed 10 times on the etched titanium plate (Ra 2.5 μ), the adhesion strength is 2. It became as low as OMPa. It can be seen that the adhesion strength is remarkably improved by interposing the CaTiO ₃ —C layer.

Separately, a pure titanium rod was subjected to the coating treatment of the present invention to form the above-described HA / CaTiO ₃ —C double layer (only one stage), and a pull-out test was performed.
As the pure titanium rod, a screw type (trade name: KOM implant) having a diameter of 3 mm and a length of 15 mm was used. For comparison, machining with an NC lathe and an electric discharge machine was performed as a “mechanical polishing” process. In addition, as a “surface blasting” treatment, blasting was performed with pure titanium powder having a special form manufactured by a hydroxide dehydrogenation method. In the pull-out test, three titanium rods each subjected to the above treatments were each planted on a canine rib, and removed together with the bone after 4 weeks. The rotation removal torque at that time was measured with a load cell universal testing machine (Ueshima Seisakusho), and the average value was obtained. The results are shown in Table 1.

  Compared to a titanium rod subjected to mechanical polishing or surface blasting, the coating of the present invention has an increased rotational removal torque value. It can be seen that the pullout resistance of the coating of the present invention is large.

さらに、ＣａＴｉＯ_３−Ｃ膜の生体内吸収速度はＨＡ膜の１０分の１であることも確認できた。したがって、ＨＡ／ＣａＴｉＯ_３−Ｃ二重層のような多層複合層とすることにより、上記したように接着力（密着強度）が増加するのみならず、吸収速度の調節を行なえるものである。

Furthermore, it was also confirmed that the in vivo absorption rate of the CaTiO ₃ -C film was 1/10 that of the HA film. Therefore, by using a multilayer composite layer such as an HA / CaTiO ₃ —C bilayer, not only the adhesive strength (adhesion strength) increases as described above, but also the absorption rate can be adjusted.

Therefore, the calcium phosphate compound-coated composite material of the present invention in which the HA / CaTiO ₃ -C multilayer structure (functionally gradient material) is arranged on the surface of the metal substrate is used as a dental implant or the like for a long period of time, for example, 10 years or more. It can be maintained in the bone.

CaTiO ₃ -C has a strong adhesive ability and ion-bonds the metal and the HA crystal, so that it is also suitable as a dental filling material, a bone defect bonding material, or the like.
Regardless of the shape of the base material, and even if the base material is an alloy, HA / CaTiO ₃ —C can be formed as a coating layer, so that it can be configured even with a complicated shape such as an artificial joint, The absorption of the coating layer at the interface can be delayed.

Since the HA / CaTiO ₃ -C layer can be formed to an arbitrary thickness, the thickness of the coating layer can be freely set according to the purpose, such as an intraosseous screw or screw that is removed after a certain period of time.
When used in dental implants, it chelates with calcium in the HA / CaTiO ₃ -C layer to prevent bacterial infections that may occur due to being in the oral cavity, ie, to impart antibacterial properties Tetracycline can be added to obtain a DDS (Drug Delivery System) material.

  The calcium phosphate compound-coated composite material of the present invention can be used in orthopedics and dentistry as a biomedical material such as an implant material, its bonding material, fracture fixing material, and artificial joint material, as well as corrosion resistance, alkali resistance, strength, insulation It is also useful as an industrial material that is required to have properties and a gradient function.

Elemental analysis diagram of synthetic calcium titanate Model structure of the synthetic calcium titanate / amorphous carbon composite of the present invention X-ray diffraction pattern of titanium plate with calcium titanate / amorphous carbon composite layer formed X-ray diffraction pattern of a titanium plate having a calcium phosphate layer formed on a calcium titanate / amorphous carbon composite layer, which is an embodiment of the calcium phosphate compound-coated composite material of the present invention Schematic cross-sectional view showing the structure of the composite material coated with calcium phosphate compound of the present invention

Claims (14)

On the metal substrate , an organic solvent solution containing titanium and calcium in a range where the Ca / Ti ratio is 1.01-1.10 is applied, and the temperature is raised at 20-200 ° C./min. via calcium titanate, amorphous carbon composite layer provided by heating and firing, calcium phosphate compound-coated composite material formed of calcium phosphate compound layer.   The calcium phosphate compound-coated composite material according to claim 1, wherein each of the calcium titanate / amorphous carbon composite layer and the calcium phosphate compound layer is composed of one or more thin films.   The calcium phosphate compound-coated composite material according to claim 1, wherein the calcium titanate / amorphous carbon composite layer and the calcium phosphate compound layer are formed in a multi-layered structure alternately. A method for producing a calcium phosphate compound-coated composite material in which a metal substrate is coated with a calcium phosphate compound layer, wherein the Ca / Ti ratio of titanium and calcium is 1. on the metal substrate prior to the formation of the calcium phosphate compound layer . the organic solvent solution containing a range to be 01-1.10 applied as a coating liquid, by heating and firing at 500 to 650 ° C. and allowed to warm at 20-200 ° C. / min, calcium amorphous titanate A method for producing a calcium phosphate compound-coated composite material, comprising forming a carbon composite layer.   5. The calcium phosphate compound-coated composite material according to claim 4, wherein the calcium phosphate compound layer is formed by applying an organic solvent solution containing phosphorus and calcium as a coating liquid and heating and firing at 500 to 650 ° C. Method.   5. The calcium phosphate compound-coated composite according to claim 4, wherein the multilayer structure is formed by repeating the step of forming the calcium titanate / amorphous carbon composite layer and the step of forming the calcium phosphate compound layer a plurality of times. A method of manufacturing the material.   The method for producing a calcium phosphate compound-coated composite material according to any one of claims 4 and 5, wherein a desired thickness is obtained by repeating application of a coating solution and heating and baking.   5. The method for producing a calcium phosphate compound-coated composite material according to claim 4, wherein the coating solution is a solution in which an organic or inorganic calcium compound and an organic titanium compound are dissolved in an organic solvent.   6. The method for producing a calcium phosphate compound-coated composite material according to claim 5, wherein the coating solution is a solution obtained by dissolving an organic or inorganic calcium compound and an organic phosphorus compound in an organic solvent.   5. The method for producing a calcium phosphate compound-coated composite material according to claim 4, wherein the metal base material is a metal or alloy selected from the group consisting of titanium, titanium alloy, stainless steel, and cobalt-chromium alloy.   10. The method for producing a calcium phosphate compound-coated composite material according to claim 8, wherein calcium 2-ethylhexanoate is used as the organic calcium compound.   9. The method for producing a calcium phosphate compound-coated composite material according to claim 8, wherein titanium tetraisopropoxide is used as the organic titanium compound.   10. The method for producing a calcium phosphate compound-coated composite material according to claim 9, wherein bis 2-ethylhexyl hydrogen phosphate is used as the organic phosphorus compound. 6. The method for producing a calcium phosphate compound-coated composite material according to claim 5, wherein an organic solvent solution containing phosphorus and calcium in a range of a Ca / P ratio of 1.75 to 1.85 is used.

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