JP2006348370A - Method for producing apatite membrane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a membrane essentially consisting of apatite and having excellent biological affinity, and a member having the membrane in extremely simple, highly operable processes. <P>SOLUTION: The apatite membrane can be formed by a process where the surface of a base material is coated with a solution composition comprising a calcium compound and a phosphorous compound in a polar solvent or a solution composition obtained by dissolving a calcium phosphate compound and apatite into a polar solvent, where the Ca/P containing ratio is controlled to 1.0 to 3.0, and heat treatment is performed, or a process where the surface of a heated base material is coated with the solution composition. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing apatite, particularly an apatite film.

Hydroxyapatite (Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ) is a ceramic typified by an alternative material for living hard tissue. Currently, it is widely used not only in the fields of dentistry and surgery, but also in daily necessities as artificial tooth roots, artificial bones, artificial joints, and bone replacement materials.

  In recent years, there is an increasing demand for medical implant materials such as artificial roots, artificial bones, and artificial joints that can be combined with bone at an early stage after implantation in the body to shorten the treatment period. These surfaces are coated with hydroxyapatite and calcium phosphate compounds having high biocompatibility. With increasing demand for these medical implant products, research has been conducted on coating the surface of a substrate such as titanium or a titanium alloy with a high-purity hydroxyapatite or a calcium phosphate compound.

  As a coating method, a plasma spraying method, a flame spraying method, a sputtering method, a laser ablation method, a spray pyrolysis method, a sol-gel method, a pyrolysis method and the like are mainly known.

  For example, a plasma spraying method represented by a physical coating method forms a film by hitting a raw material hydroxyapatite on a substrate at a high speed of 100 to 200 m / s in a semi-molten state at a high temperature of 10,000 ° C. In the flame spraying method, hydroxyapatite particles are introduced into an oxygen propylene flame at 2950 ° C. at a speed of 1350 m / s and applied onto a substrate to form a film (see, for example, Non-Patent Document 1).

  In the sputtering method, as shown in Non-Patent Document 2, it is not easy to produce hydroxyapatite.

  In the spray pyrolysis method, a solution containing calcium nitrate, ammonium monohydrogen phosphate and nitric acid is sprayed onto a heated alumina substrate to form a film while simultaneously evaporating the solvent and thermally decomposing unnecessary components. After film formation, the apatite film is formed by heating at 1200 ° C. in a water vapor atmosphere (see, for example, Non-Patent Document 3).

  In the solution process, there is a method of creating an apatite thin film by immersing a titanium plate heated to 200 ° C. in an aqueous solution containing calcium nitrate, ammonium monohydrogen phosphate, and urea, and then transferring and immersing it in a simulated body fluid ( For example, see Patent Document 1.)

In addition, a sol-gel method typified by a chemical method (for example, see Patent Document 2) and a thermal decomposition method (for example, see Patent Document 3) include film preparation methods by coating and heat-treating each solution. Recently, phosphoric acid and phosphoric acid compounds were added to the chemistry of hydroxyapatite in a homogeneous solution obtained by reacting alkylamine and calcium salt of ethylenediamine N, N, N ′, N′tetraacetic acid in alcohol. There is a report that a hydroxyapatite thin film can be formed by coating and heat treatment using an alcohol solution synthesized by adding a stoichiometric ratio (see, for example, Patent Document 4). Compared with the alkoxide-containing solution of the sol-gel method, the stability of the solution is extremely high, and it can be applied to all coating methods such as a spray coating method as well as a dip method and a flow coating method. In addition, a useful chemical film forming method capable of uniformly coating a complex shape without depending on the shape of the substrate by a solution method has been reported.
Shigeyuki Soumiya, Ryuji Ohno, Masayuki Kaneno, Junichi Kimura, Tsutomu Tsunooka, Yotaro Matsuno, “Guide for Ceramics and Applications”, Gihodo Publishing, p. 322-338 (2002) S. Nakamura, M .; Ohgaki, T .; Kobayashi, J. et al. Hamagami and K.K. Yamashita, “Bioceramics, 12”, p. 467-470 (1999) Tetsuhei Yamamoto, Mamoru Aizawa, Kiyoji Itaya, Hiroshi Suemasa, Akira Nosue, Isao Okada “Abstracts of Annual Meeting of the Ceramic Society of Japan JST Document Number: X0505A Vol. 1999”, page 430 (1999.03.25) JP-A-11-323570 JP-A 61-295215 Japanese Patent Publication No. 3-60502 JP 2004-33589 A

  In the above-mentioned prior art, in Non-Patent Document 1, since the melting point of hydroxyapatite is 1700 ° C., decomposition or vitrification may occur in a part of the produced film. For this reason, a recrystallization step may be necessary after coating. The resulting film has a thickness of 10 to several hundred μm, and there is a problem that cracks, peeling and the like are likely to occur. Moreover, it is not easy to coat a complex shape.

  Further, in the sputtering method shown in Non-Patent Document 2, it is not easy to produce a hydroxyapatite target, and it is difficult to obtain a homogeneous film. In addition, from the principle of film formation, coating with a film thickness of 1 μm or more takes a lot of time and requires annealing for crystallization and a step of introducing a hydroxyl group. In addition, it is not easy to coat a complicated shape.

  And since these film forming methods go through a high-temperature heat treatment step, there is a possibility that the strength of the base material deteriorates due to heat. In addition, the apparatus is very expensive, and there is a problem that the initial investment of the equipment becomes enormous in mass production.

  Furthermore, the spray pyrolysis method is difficult to apply to a titanium material, which is a biomaterial, because the steam treatment after film formation is limited to materials that can withstand high temperatures such as alumina because of high temperatures. In addition, there is a problem that large energy is required for mass production because high-temperature steam treatment is performed.

  In addition, in the solution process, the immersion time in the simulated body fluid takes several days to several tens of days. Therefore, there is a problem that a considerable time is required until the target apatite film thickness is obtained.

  The sol-gel method and the thermal decomposition method are simple in film formation, and can be coated on a complicated shape by dip coating or spin coating. The apparatus is also characterized in that it is less expensive than the physical film-forming method described above.

  However, in the sol-gel method of Patent Document 2, the sol-gel solution is composed of a condensate in the hydrolysis of metal alkoxide and metal salt, so that the stability to water is poor. When a plurality of components are mixed, the hydrolysis rate depends on each component. Therefore, it is difficult to prepare a uniform solution. Moreover, environmental control of temperature and humidity is necessary at the time of film formation, and there is a problem that the film quality of the film obtained varies depending on the environment.

  In Patent Document 3 of the thermal decomposition method, a homogeneous solution synthesized by adding a phosphoric acid compound to a product obtained by reacting calcium oxide with an organic acid such as 2-ethylhexanoic acid and diluting with alcohol is compared with a sol-gel solution. It is characterized by high stability, and a useful film forming method for producing a hydroxyapatite film by coating and heat treatment has also been reported.

  Although the chemical film-forming method using these solutions has the feature that the film thickness can be controlled by adjusting the concentration of the liquid, the film thickness by one coating is limited to about 0.5 to 1 μm, When the target film thickness is several μm, it is necessary to stack them. For this reason, the heat treatment temperature is often lower than that of a physical method, but a heat treatment step corresponding to the number of laminations is required, and the strength of the base material may be deteriorated. Many chemical film-forming methods use a large amount of alcohol or an organic solvent as a solvent, and solutes contain additives that adjust hydrolysis and various organic compounds that stabilize calcium and phosphorus. For this reason, at the time of a coating, the installation which prevents the excess liquid which came out of the process from flowing out outside may be required, and ventilation equipment may be required. Moreover, although it is a small amount, a toxic gas may be generated during heat treatment. Furthermore, due to the high adsorptive power, which is also a characteristic of apatite, when heat treatment is insufficient, there is also a problem that the organic component remains adsorbed on the apatite produced by the unburned organic component.

  Due to the recent trend of low VOC and low environmental load material development, it is desired to develop a low-pollution solution in the chemical film-forming method. Titanium materials used for medical implants undergo a phase transition from α-type to β-type at a temperature of 882 ° C. or higher, and the strength is significantly reduced. A short time is desired.

  As described above, it is generally not easy to form a strong apatite film at a low temperature at which the strength of the base material does not deteriorate using components having a low VOC and a low environmental load.

  The present invention solves the above-described problems, and an object of the present invention is to provide a novel method for producing apatite using a solution composition that is easy to handle with low environmental load.

  Another object of the present invention is to provide a film having apatite as a main component and the member having the film.

  The present invention can solve the above problems by the following configuration.

  (1) Add a calcium compound and at least a phosphorus compound to a solvent that is a single or a mixture of polar solvents such as water, carbonated water, hydrogen peroxide solution, methanol, ethanol, propanol, and butanol. A method for producing an apatite film characterized by the above.

  (2) The method for producing an apatite film according to (1), wherein the phosphorus compound is a phosphate compound.

  (3) The method for producing an apatite film as described in (2) above, wherein the phosphoric acid compound is a phosphate such as phosphoric acid, orthophosphoric acid, metaphosphoric acid, and diphosphoric acid.

  (4) The method for producing an apatite film according to (1) above, wherein the solution is a solution adjusted to a concentration such that the solute does not precipitate.

  (5) The method for producing an apatite film according to (1), wherein the ratio of calcium ion to phosphate ion (Ca / P) in the solution is 1.0 to 3.0.

  (6) The hydroxyapatite and the hydroxyapatite in the hydroxyapatite are either a single or a mixture of carbonated hydroxyapatite in which either a phosphate group or a hydroxyl group, or both are partially substituted with a carbonate group. The method for producing an apatite film as described in (1) above.

  (7) Apatite film characterized by dissolving a calcium phosphate compound in a solvent such as water, carbonated water, hydrogen peroxide solution, methanol, ethanol, propanol, butanol or the like alone or in a mixture thereof. Manufacturing method.

(8) The calcium phosphate compound contains Ca (H ₂ PO ₄ ) ₂ .H ₂ O (primary calcium phosphate), Ca ₄ P ₂ O ₉ (tetracalcium phosphate), α-Ca ₃ (PO ₄ ) ₂ (α- tribasic calcium phosphate), CaHPO ₄ (dibasic calcium _{phosphate), Ca 8 H 2 (PO} 4) 6 · 5H 2 O ( calcium -octalin _{acid), β-Ca 3 (PO} 4) 2 (β- tricalcium phosphate), hydroxyapatite and the like The method for producing an apatite film according to the above (7), wherein each of the above is independent or a mixture thereof.

  (9) An apatite film produced by the method according to any one of (1) to (8).

  (10) A member having a film containing apatite as a main component, which is produced by the method according to any one of (1) to (8).

  The present invention is a polar solvent solution containing a calcium compound and a solution composition containing a phosphorus compound, or a solution composition in which a calcium phosphate compound and apatite are dissolved in a polar solvent, and the Ca / P ratio contained is 1.0 to 3. After coating the solution composition controlled to 0 on the surface of the substrate, heat treatment, or coating the solution composition on a heated substrate, a very simple and good workability process, such as cracking, peeling, It was also found that a film mainly composed of an apatite film free from defects such as pinholes and a member having the film can be obtained regardless of the shape and form of the substrate. As a result, the present invention can be applied to the manufacture of medical instruments such as medical implant materials that require high biocompatibility, and decorative articles.

  In the present invention, a polar solvent solution containing a calcium compound and a solution composition containing a phosphorus compound, or a solution composition in which apatite and a calcium phosphate compound are dissolved in a polar solvent, a film mainly composed of apatite and the member having the film Is created.

  The solution composition used first in the present invention is obtained by mixing a polar solvent solution obtained by dissolving a calcium compound in a polar solvent and a phosphorus compound. Preferably, the resulting solution composition is uniform and transparent.

  The solution composition used in the second aspect of the present invention is obtained from a solution composition in which a calcium phosphate compound and apatite are dissolved in a polar solvent. Preferably, the resulting solution composition is uniform and transparent.

  Examples of the polar solvent used in the present invention include water, carbonated water, aqueous hydrogen peroxide, methanol, ethanol, propanol, isopropanol, butanol and other lower alcohols, ethylene glycol, propylene glycol and other glycols, ethylene glycol monobutyl ether, propylene glycol Although glycol ethers, such as monomethyl ether, are mentioned, it is not limited to these. These polar solvents may be used alone or in combination of two or more.

  Calcium compounds used in the present invention include calcium bromide, calcium citrate, calcium chloride, calcium carbonate, calcium hydrogen carbonate, calcium iodide, calcium nitrate, calcium oxalate, calcium acetate, calcium hydroxide, hypophosphorous acid Examples include, but are not limited to, calcium, dimethoxycalcium, diethoxycalcium, dipropoxycalcium, di-i-propoxycalcium, di-i-butoxycalcium, dibutoxycalcium, di-sec-butoxycalcium and the like. These may be used alone or in combination of two or more. These compounds may contain water-soluble metal ions in addition to calcium, but it is desirable that there be no metal other than calcium in order to synthesize high-purity hydroxyapatite.

  Examples of the phosphorus compound used in the present invention include orthophosphoric acid, metaphosphoric acid, diphosphoric acid, hypophosphoric acid, dimethyl phosphate, diethyl phosphate, dibutyl phosphate, methyl diisopropyl phosphate, ethyl phosphate, and propyl phosphate. , Isopropyl phosphate, butyl phosphate, lauryl phosphate, stearyl phosphate, 2-ethylhexyl phosphate, trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tri-i-butyl phosphate, tributyl phosphate, phosphoric acid Tri-sec-butyl, trioctyl phosphate, tricresyl phosphate, tris (2-ethylhexyl) phosphate, tris (2-butoxyethyl) phosphate, tritol phosphate, diethyl phosphite, trimethyl phosphite, phosphorous acid Triethyl, phosphonoacetic acid, phosphonoformic acid, phosphonopropionic acid, triphenylphospho Fin oxide, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, tetrabutylammonium phosphate, adenosine monophosphate, adenosine diphosphate, adenosine triphosphate, inosinic acid, guanylic acid, phosphinic acid, etc., and salts thereof However, the phosphoric acid, the metaphosphoric acid, the phosphorous acid, and the hypophosphorous acid compound are not limited thereto. These may be used alone or in combination of two or more. These compounds may contain water-soluble metal ions in addition to calcium, but it is desirable that there be no metal other than calcium in order to synthesize high-purity hydroxyapatite.

  The phosphorus compound is added so that the Ca / P ratio in the solution composition is 1.0 to 3.0, more preferably 1.0 to 2.5. When it deviates from this range and is less than 1.0, a film mainly composed of hydroxyapatite cannot be obtained, and a film composed mainly of a calcium phosphate compound other than apatite becomes unfavorable. Moreover, when it exceeds 2.5, an alkali component will become excess and biocompatibility will fall.

  It is preferable that pH of the said solution composition exists in the range of 3-13. More preferably, the pH is in the range of 5-10. Within this range, the substrate can be prevented from being eroded and the solution composition can be easily handled. If the pH deviates from this range and the pH is less than 3, it is difficult to produce acid-resistant apatite due to the acidic environment, and only apatite with low crystallinity is produced. When the pH is higher than 13, the solute component is hydrolyzed to form a hydroxide precipitate, resulting in a non-uniform solution and not suitable for coating.

  The substrate used in the present invention is a metal substrate such as titanium, titanium alloy, stainless alloy, nickel-chromium alloy, cobalt-chromium alloy, etc., polymer substrate, glass substrate, ceramic substrate such as titania, alumina, zirconia. Materials. A person skilled in the art can arbitrarily select a substrate which can coat the solution composition and has a melting point equal to or higher than the heat treatment temperature. Further, the shape, form, and surface state of the substrate are not limited, and the surface may be smooth or rough. More specifically, examples thereof include medical implant devices such as artificial tooth roots, artificial bones, and artificial joints, catalyst materials, catalyst support materials, adsorbent materials, decorative products, and daily necessities. Although an example was given here, it is not limited to these.

  The obtained solution composition is coated on a substrate and heat treated, or coated on a heated substrate to form an apatite film. There is no limitation on the coating method, and when a person skilled in the art manufactures an apatite film, it can be appropriately selected according to the form, shape and surface state of the substrate. As a coating method to be used, for example, spin coating, dip coating, spray coating, flow coating or the like is used for coating.

The substrate coated in this manner is heat-treated at 50 ° C to 1200 ° C, preferably 100 ° C to 1000 ° C, more preferably 110 ° C to 600 ° C. Moreover, you may coat a solution composition on the base material heated to the said temperature range. When heat treatment is performed at a low temperature outside this range, the heat treatment is insufficient, and peeling may occur when overcoating or the like. Further, when the heat treatment is performed at a high temperature, the composition of the produced apatite is changed, and β-Ca ₃ (PO ₄ ) ₂ (β-tricalcium phosphate) may be produced in addition to the apatite. In addition, the said heat processing temperature is an illustration and is not limited to these.

  The heat treatment time can be appropriately selected and set by those skilled in the art depending on the type of coating material and the coating method. For example, it can be performed in 10 seconds to 5 hours, preferably 5 minutes to 2 hours. Moreover, when coating a solution composition on the base material of the heated state, when a base material can coat a solution composition, maintaining the said temperature range, heat processing and a coating process can be performed simultaneously.

  In addition, the said heat processing time is an illustration and is not limited to these.

  In the present invention, the coating and heat treatment steps can be carried out once or a plurality of times, or the coating can be carried out once or more times on a heated substrate to produce a thick film of several tens of micrometers from a thin film of about 10 nm it can. After coating, if necessary, the film and the member having the film are boiled with water to perform washing and improvement of crystallinity, thereby completing the film forming process. A person skilled in the art can select a concentration of a solution composition, a coating method, and coating conditions to obtain a film mainly composed of apatite having an arbitrary film thickness and a member having the film. The above coating and heat treatment steps are examples, and are not limited to these.

  The film mainly composed of apatite obtained by the present invention and the member having the film may be used as they are, or a film or the like can be further applied by utilizing the high adhesion to the base material. It is. In this case, the type of film and the construction method are not limited. Moreover, about the said usage method, it is an illustration and it is not limited to these.

  The present invention is not limited to the best mode for carrying out the invention described above, and various other configurations can be adopted without departing from the gist of the present invention.

  The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

  While stirring 1000 mL of ion-exchanged water with a stirrer in a 1000 mL beaker, 0.52 g (5.20 mmol) of calcium carbonate was added to obtain a suspended solution. The suspension was completely dissolved by stirring at room temperature for 3 hours while bubbling carbon dioxide.

  3.12 mmol of phosphorus component corresponding to 0.36 g of 85% phosphoric acid (Ca / P = 1.67) of hydroxyapatite diluted with 50 mL of ion exchange water in the obtained aqueous calcium hydrogen carbonate solution ) And further stirred at room temperature for 10 minutes to obtain a clear solution composition.

  After polishing to a mirror surface (Ra = 0.03 μm), a washed titanium plate with a purity of 99% or more is heated on a heater to 160-190 ° C., and 100 ml of this solution composition is sprayed intermittently to form a titanium plate. A white film was formed on top. The obtained film was identified by thin film X-ray diffraction measurement using MXP-18AHF22 manufactured by Mac Science and infrared absorption spectrum measurement using FT-IR1600 manufactured by Shimadzu. As a result, only the titanium peak derived from the substrate was observed in addition to the peak attributed to hydroxyapatite from the thin film X-ray diffraction measurement (FIG. 1). From the infrared absorption spectrum measurement, only absorption peaks attributed to hydroxide, phosphoric acid and carbonic acid were observed (FIG. 2). From these results, it was confirmed that a carbonated hydroxyapatite film was obtained. The film thickness was measured by DEKTAK-3 stylus method. As a result, the film thickness was about 4 μm.

  The solution composition obtained in Example 1 was spray-coated on an unpolished titanium plate (Ra = 0.23 μm) under the same conditions. The obtained film was identified by the same thin film X-ray diffraction measurement and infrared absorption spectrum measurement as in Example 1. As a result, only the titanium peak derived from the substrate was observed in addition to the peak attributed to hydroxyapatite from the thin film X-ray diffraction measurement (FIG. 3). From the infrared absorption spectrum measurement, only absorption peaks attributed to hydroxide, phosphoric acid and carbonic acid were observed (FIG. 4). From these results, it was confirmed that a carbonated hydroxyapatite film was obtained. Moreover, although this film | membrane was boiled in water for 5 hours, peeling of the film | membrane did not occur.

  The surface state of the prepared carbonated hydroxyapatite film was observed using a S-4200 field emission scanning electron microscope manufactured by Hitachi. FIG. 5 shows an electron micrograph of an unpolished titanium substrate surface, and FIG. 6 shows an electron micrograph of a carbonated hydroxyapatite film coated on the titanium substrate. As a result, it was found that the entire surface of the unpolished titanium substrate having a rough surface was covered with carbonated hydroxyapatite without any gaps.

  The solution composition obtained in Example 1 was blasted with alumina having a particle diameter of 50 μm, and then spray-coated on the cleaned titanium plate (Ra = 0.65 μm) under the same conditions as in Examples 1 and 2. The obtained film was identified by the same thin film X-ray diffraction measurement and infrared absorption spectrum measurement as in Example 1. As a result, it was confirmed that a carbonated hydroxyapatite film was obtained in the same manner as in Example 1 and Example 2. Moreover, although this film | membrane was boiled in water for 5 hours, peeling of the film | membrane did not occur.

  The surface state of the carbonate-containing hydroxyapatite film was observed with an electron microscope in the same manner as in Example 2. FIG. 7 shows an electron micrograph of the surface of a blasted titanium substrate, and FIG. 8 shows an electron micrograph of a carbonated hydroxyapatite film coated on the titanium substrate. As a result, it was found that the carbon-containing hydroxyapatite covered the entire surface of the unpolished titanium substrate having a rough surface (Ra = 0.65 μm) without any gaps.

  Moreover, the cross-sectional state of this film was observed with an electron microscope. FIG. 9 shows a cross-sectional photograph of the film. It was found that the carbonated hydroxyapatite was coated following all the surface irregularities.

  While stirring 1000 mL of ion-exchanged water with a stirrer in a 1000 mL beaker, 0.50 g (0.5 mmol) of carbonated hydroxyapatite synthesized by a chemical wet method was added to obtain a suspension solution. The suspension was stirred at room temperature for 7.5 hours while bubbling carbon dioxide.

  The obtained suspension solution was filtered, and the amount of dissolution was determined from the weight of the undissolved carbonate-containing hydroxyapatite (0.15 g dissolution), and 0.87 mmol / g phosphorus obtained by diluting 85% phosphoric acid about 10 times. Add 1.02 g of acid aqueous solution (0.89 mmol phosphorus component corresponding to hydroxyapatite stoichiometric ratio (Ca / P = 1.67)) and stir for another 10 minutes at room temperature to form a clear solution composition Got.

  When the same titanium plate as in Example 2 was heated to 240 ° C. on a heater, 100 mL of this solution composition was intermittently sprayed to form a white film on the titanium plate. The obtained film was identified by the same thin film X-ray diffraction measurement and infrared absorption spectrum measurement as in Example 1. As a result, from the thin film X-ray diffraction measurement, only the peak of titanium derived from the substrate was observed in addition to the peak attributed to hydroxyapatite. From the infrared absorption spectrum measurement, only absorption peaks attributed to hydroxide, phosphoric acid and carbonic acid were observed. From these results, it was confirmed that a carbonated hydroxyapatite film was obtained.

Graph of thin film X-ray diffraction measurement results of a film prepared on a mirror-polished titanium plate Graph of IR measurement results of film prepared on mirror-polished titanium plate Graph of thin film X-ray diffraction measurement results of a film prepared on an unpolished titanium plate Graph of IR measurement result of film prepared on unpolished titanium plate Scanning electron micrograph of unpolished titanium substrate surface Scanning electron micrograph of an apatite film coated on an unpolished titanium substrate Scanning electron micrograph of the surface of a blasted titanium substrate Scanning electron micrograph of apatite film coated on blasted titanium substrate It is a cross-sectional photograph of an apatite film coated on a blasted titanium substrate.

Claims (10)

  A polar solvent such as water, carbonated water, hydrogen peroxide solution, methanol, ethanol, propanol, butanol, etc., and a calcium compound and at least a phosphorus compound are added to a solvent that is each alone or a mixture thereof. A method for manufacturing an apatite film.   The method for producing an apatite film according to claim 1, wherein the phosphorus compound is a phosphate compound.   The method for producing an apatite film according to claim 2, wherein the phosphoric acid compound is a phosphate such as phosphoric acid, orthophosphoric acid, metaphosphoric acid, and diphosphoric acid.   2. The method for producing an apatite film according to claim 1, wherein the solution is a solution adjusted to such a concentration that the solute does not precipitate.   The method for producing an apatite film according to claim 1, wherein the ratio of calcium ion to phosphate ion (Ca / P) in the solution is 1.0 to 3.0.   Apatite is characterized in that hydroxyapatite, hydroxyapatite containing hydroxyapatite in which either or both of phosphoric acid groups and hydroxyl groups in hydroxyapatite are partially substituted with carbonate groups are each alone or a mixture thereof. The method for producing an apatite film according to claim 1.   A method for producing an apatite film, wherein a calcium phosphate compound is dissolved in a polar solvent such as water, carbonated water, hydrogen peroxide solution, methanol, ethanol, propanol, or butanol, either alone or in a mixture thereof. . Calcium phosphate _{compound, Ca (H 2 PO 4)} 2 · H 2 O ( monocalcium _{phosphate), Ca 4 P 2 O 9} ( tetracalcium _{phosphate), α-Ca 3 (PO} 4) 2 (α- tricalcium phosphate ), CaHPO ₄ (dibasic calcium _{phosphate), Ca 8 H 2 (PO} 4) 6 · 5H 2 O ( calcium -octalin _{acid), β-Ca 3 (PO} 4) 2 (β- tricalcium phosphate), each of apatite alone The method for producing an apatite film according to claim 7, wherein the apatite film is a mixture thereof.   An apatite film produced by the method according to any one of claims 1 to 8.   A member having a film mainly composed of apatite, which is produced by the method according to claim 1.