JP6730115B2 - Metallic materials and bioimplants - Google Patents

Description

The present invention relates to metallic materials and bioimplants.

Conventionally, various studies have been conducted on surface modification in which various functions are given to the surface of a material by injecting various ions into the surface of the material, and it has been industrially put to practical use. For example, a metal material whose surface is implanted with fluorine ions is known (see, for example, Patent Document 1 and Non-Patent Document 1). Non-Patent Document 1 reports that implantation of fluorine ions into the surface of titanium reduces the number of viable bacteria on the surface. Therefore, when fluorine ions are injected into the surface of the metal material, it is expected that antibacterial property can be imparted to the surface.

On the other hand, as the effects obtained by making the surface of the material hydrophilic, there are a self-cleaning effect in a water environment and a friction and wear reducing effect by forming a fluid film in a water environment. Therefore, if the surface of the metal material into which the above-mentioned fluorine ions are implanted can be made hydrophilic, antifouling properties that promote antibacterial properties, abrasion resistance, etc. can be imparted to the surface, and various fields including biological implants and the like. It is considered to be an antibacterial material that can be applied to.

However, when fluorine ions are injected into the surface of the material, the surface usually changes to hydrophobic due to the characteristics of the generated fluoride. Therefore, it is known that a metal material into which fluorine ions are injected has a hydrophilic surface. I didn't.

Japanese Patent No. 4568396

M. Yoshinari, Y.Oda, T.Kato, K.Okuda, ``Influence of surface modifications to titanium on antibacterial activity in vitro'', Biomaterials, 2001, 22, p. 2043-2048

An object of the present invention is to provide a metallic material and a biological implant in which the surface of a material into which fluorine ions have been implanted has hydrophilicity.

As a result of intensive studies to solve the above problems, the present inventors have found a solution means having the following constitution, and completed the present invention.
(1) A metal material in which fluorine ions are implanted into the surface of the material and the surface of the material has hydrophilicity.
(2) The metal material according to (1), wherein the contact angle of water with respect to the surface of the material is 80° or less.
(3) The metal material according to (2), wherein the contact angle is 60° or less.
(4) The metal material according to any of (1) to (3), wherein the fluorine atom concentration on the surface of the material is 4.3×10 ^{19 to} 1.7×10 ²¹ atoms/cm ³ .
(5) The metal material according to any one of (1) to (4), which includes a fluorine ion implantation layer having a thickness of 30 to 800 nm in a depth direction from the surface of the material.
(6) The metal material according to (5), wherein the fluorine ion-implanted layer contains at least one of CrF, CrF ₂ , CrF ₃ and CrF ₄ .
(7) In any one of (1) to (6) above, comprising a metal and an oxide film layer laminated on the surface of the metal, wherein the surface of the material is the surface of the oxide film layer. The metal material described.
(8) The metal material according to (7), wherein the oxide film layer has a thickness of 2 nm or more.
(9) The fluorine ion implantation layer is provided in the depth direction from the surface of the material, and the thickness of the fluorine ion implantation layer is larger than the thickness of the oxide film layer. Metal material.
(10) The metal material according to any one of (1) to (9), wherein the metal forming the metal material is stainless steel or a cobalt-chromium-molybdenum alloy.
(11) A living body implant made of the metal material according to any one of (1) to (10) above.

According to the present invention, since fluorine ions are injected into the surface of the material and the surface of the material has hydrophilicity, the surface of the material has antibacterial properties as well as antifouling property and water environment caused by hydrophilicity. There is an effect that abrasion resistance (lubricity) and the like can be further imparted.

It is a partial expanded schematic cross section explanatory drawing which shows the metal material which concerns on one Embodiment of this invention. It is a graph which shows the measurement result of the dynamic friction coefficient (Student's t-test) in water in an Example.

Hereinafter, the metal material according to the embodiment of the present invention will be described in detail with reference to FIG.
In the metallic material 1 of the present embodiment shown in FIG. 1, fluorine ions (F ⁺ ) are implanted into the material surface 11, and the material surface 11 has hydrophilicity. In other words, the metal material 1 of this embodiment includes the fluorine ion implantation layer 2 in the depth direction A from the surface 11 of the material, and the surface 11 of the material has hydrophilicity. With such a configuration, in addition to the antibacterial property due to the implantation of fluorine ions, the surface 11 of the material can be further provided with antifouling property due to hydrophilicity, abrasion resistance in a water environment, and the like. Implantation means ionizing atoms of interest and applying energy to physically invade another object. Hereinafter, the metal material 1 of this embodiment will be specifically described.

The contact angle of water with respect to the surface 11 of the material is preferably 80° or less, more preferably 60° or less, and further preferably 55° or less. According to such a configuration, the surface 11 of the material exhibits high wettability with respect to water, so that the surface 11 of the material becomes hydrophilic. The contact angle of water described above is a static contact angle, and is a value measured with reference to ISO 15989, as described in Examples described later. The lower limit of the contact angle of water is not particularly limited.

In order to make the contact angle of water with respect to the surface 11 of the material the above-mentioned specific value, for example, the concentration of fluorine atoms on the surface 11 of the material may be adjusted. The fluorine atom concentration on the surface 11 of the material is preferably 4.3×10 ^{19 to} 1.7×10 ²¹ atoms/cm ³ (atom/cm ³ ), more preferably 1.2×10 ^{20 to} 1.4×. It is 10 ²¹ atoms/cm ³ , and more preferably 3.1×10 ^{20 to} 1.1×10 ²¹ atoms/cm ³ . In other words, the fluorine atom concentration on the surface 11 of the material is preferably 0.05 to 2.0 atom% (atom %), more preferably 0.1 to 1.6 atom %, and still more preferably 0.4 to 1. It is 3 atomic %. According to such a configuration, the surface 11 of the material can be provided with antibacterial properties, the contact angle to water is likely to be the specific value described above, and the surface 11 of the material into which the fluorine ions have been implanted is rendered hydrophilic. Tend to have. The reason for this is presumed to be as follows.

That is, it is considered that when the fluorine ions are implanted into the surface 11 of the material, the following two effects occur simultaneously.
(I) The effect that the charge of the host crystal is biased by high electronegativity (II) The hydrophobic effect due to the formation of fluoride

Among the above-mentioned two effects, the effect that the charge of the mother crystal of (I) is biased is the following effect. When implanting fluorine ions into the surface 11 of the material, first, fluorine (F) is plasmatized into F ⁺ by a high frequency power source. F ⁺ is accelerated by the applied voltage and injected into the metal material 1. As a result, F ⁺ penetrates into the crystal lattice. F has the highest electronegativity of all elements, and the stable ion is F ⁻ . Therefore, F ⁺ is e in the crystal lattice which has entered ^- to steal a. Depletion of e ⁻ by F ⁺ causes bias in the charge of the mother crystal. As a result, the affinity with water, which is a polar solvent, is improved.

Here, it is considered that in a conventional metal material into which fluorine ions are implanted, the amount of fluorine ions implanted is large, and many fluorides are formed on the surface of the material, so that the surface of the material becomes hydrophobic. When the implantation amount of fluorine ions is relatively small, the concentration of fluorine atoms on the surface 11 of the material falls within the above numerical range. In addition, the fluorine atom concentration usually has a peak within several nm from the surface 11 of the material. Therefore, if the implantation amount of fluorine ions is relatively small and the concentration of fluorine atoms on the surface 11 of the material is within the above-mentioned numerical range, the concentration of fluoride formed on the surface 11 of the material can be lowered. As a result, on the surface 11 of the material, the effect that the charge of the mother crystal is biased by the penetration of fluorine ions is mainly exerted rather than the hydrophobic effect due to the formation of the fluoride. Is supposed to have hydrophilicity.

The above-mentioned fluorine atom concentration is a value measured by secondary ion mass spectrometry (hereinafter sometimes referred to as "SIMS"), as described in Examples described later.

As described above, the metal material 1 of this embodiment includes the fluorine ion implantation layer 2 in the depth direction A from the surface 11 of the material. The fluorine ion-implanted layer 2 is a layer formed by implanting fluorine ions into the surface 11 of the material, and has a fluorine atom concentration of 1 ppm or more. The fluorine atom concentration in the fluorine ion-implanted layer 2 usually reaches a peak within a few nm from the surface 11 of the material and then gradually decreases.

The fluorine ion-implanted layer 2 is a layer containing a fluoride of fluorine and a constituent element of the metal 3 described later. Examples of the fluoride include CoF ₂ (cobalt (II) fluoride), CoF ₃ (cobalt (III) fluoride), CoF ₄ (cobalt (IV) fluoride), CrF (chromium (I) fluoride), CrF ₂ (Chromium (II) fluoride), CrF ₃ (Chromium (III) fluoride), CrF ₄ (Chromium (IV) fluoride), MoF ₄ (Molybdenum (IV) fluoride), MoF ₆ (Molybdenum fluoride) (VI)), FeF ₂ (iron (II) fluoride), FeF ₃ (iron (III) fluoride), NiF ₂ (nickel (II) fluoride) and the like, but not limited to these. Absent. The fluorine ion implantation layer 2 may include at least one of CrF, CrF ₂ , CrF ₃ and CrF ₄ .

On the other hand, the metal material 1 of the present embodiment further includes the metal 3 and the oxide film layer 4 laminated on the surface 31 of the metal 3. Then, in the metal material 1 of the present embodiment, the surface 11 of the above-described material is the surface 41 of the oxide film layer 4.

Examples of the metal 3 constituting the metal material 1 include, but are not limited to, stainless steel (SUS), cobalt-chromium-molybdenum alloy (CCM alloy), and the like.

Examples of the composition of the oxide film layer 4 laminated on the surface 31 of the metal 3 include chromium oxide. Examples of the chromium oxide include Cr ₂ O ₃ (chromium (III) oxide).

Here, in the present embodiment, the thickness D1 of the above-mentioned fluorine ion implantation layer 2 is larger than the thickness D2 of the oxide film layer 4. With such a configuration, it is possible to maximize the effect of making the surface 11 of the material hydrophilic by the implantation of fluorine ions, that is, the hydrophilization effect. More specifically, the oxide film layer 4 and the metal 3 are also present in the region of the metal material 1 where the fluorine ion implantation layer 2 is present. In other words, fluorine ions are implanted into the oxide film layer 4 and the metal 3 which coexist with the fluorine ion implantation layer 2 in the metal material 1. By the way, even if fluorine ions are implanted into the metal 3, since the metal 3 usually has conductivity and the free electrons are sufficiently supplied, it is considered that the bias of the charge is unlikely to occur in the metal 3. On the other hand, since the oxide film layer 4 is usually a semiconductor, it is considered that the bias of charges due to fluorine ions is more likely to occur than that of the metal 3. Therefore, it is considered that when the fluorine ions are implanted into all of the oxide film layer 4, the bias of the charges becomes large and the oxide film becomes more hydrophilic. When the thickness D1 of the fluorine ion-implanted layer 2 is larger than the thickness D2 of the oxide film layer 4, since the fluorine ions are injected into all of the oxide film layer 4, the hydrophilization effect by the injection of the fluorine ions is maximized. It is possible to make the most of it.

The thickness D1 of the fluorine ion implantation layer 2 is preferably 30 to 800 nm. With such a configuration, the thickness D1 of the fluorine ion-implanted layer 2 is likely to be larger than the thickness D2 of the oxide film layer 4, and fluorine ions are easily implanted into all of the oxide film layer 4. Examples of the method for measuring the thickness D1 of the fluorine ion-implanted layer 2 include a method of determining a portion of the metal material 1 having a fluorine atom concentration of 1 ppm or more as the fluorine ion-implanted layer 2, and measuring the thickness thereof. To be

The thickness D2 of the oxide film layer 4 is preferably 2 nm or more. With such a configuration, the following effects can be obtained. That is, it is considered that the thickness D2 of the oxide film layer 4 in the metal material 1 matches the thickness of the electrification layer that contributes to the hydrophilicity. Therefore, if the thickness D2 of the oxide film layer 4 is too small, the hydrophilization effect is sufficient. May not be exhibited. When the thickness D2 of the oxide film layer 4 is 2 nm or more, the oxide film layer 4 has a thickness required to exert the hydrophilic effect.

Further, when the thickness D2 of the oxide film layer 4 is set to 10 nm or more by the oxidation treatment, the surface 11 of the material can be colored in various color tones. As a specific example, when the metal 3 is stainless steel or a cobalt-chromium-molybdenum alloy, the thickness of the oxide film layer made of chromium oxide is set as follows to make the surface 11 of the material have various color tones. It is possible to develop color.
The thickness D2 of the oxide film layer 4 is 10 nm or more and 70 nm or less: Gray The thickness D2 of the oxide film layer 4 is 70 nm or more and 90 nm or less: Purple The thickness D2 of the oxide film layer 4 is 90 nm or more and 100 nm or less: Blue Oxide film layer The thickness D2 of 4 is more than 100 nm and 120 nm or less: Green The thickness D2 of the oxide film layer 4 is more than 120 nm and 130 nm or less: Yellow The thickness D2 of the oxide film layer 4 is more than 130 nm and 160 nm or less: Red

By using the color tone described above, for example, when the metal material 1 is used as a material for a living body implant, the surface of the living body implant can be colored in various colors to visually determine the type of the living body implant. Mixing of implants can be suppressed. Further, the thickness D2 of the oxide film layer 4 can be easily determined by using the color tone described above. Note that the thickness D2 of the oxide film layer 4 can be measured by, for example, observing the cross section of the metal material 1 with a microscope, in addition to the determination based on the color tone. The upper limit of the thickness D2 of the oxide film layer 4 is preferably smaller than the thickness D1 of the fluorine ion implantation layer 2.

In order to stack the oxide film layer 4 on the surface 31 of the metal 3, for example, the metal 3 may be subjected to an oxidation treatment. Examples of the oxidation treatment include natural oxidation, anodic oxidation, atmospheric heat treatment, oxygen plasma treatment, acid treatment, alkali treatment, laser irradiation treatment and the like. Examples of the acid treatment include dipping in an acid solution. Examples of the alkali treatment include immersion in an alkaline solution.

The natural oxidation, anodic oxidation, atmospheric heat treatment, oxygen plasma treatment and acid treatment among the exemplified oxidation treatments and the thickness D2 of the oxide film layer 4 to be laminated tend to have the following relationship.
(Thickness D2 of oxide film layer 4)
Natural oxidation: 2-5 nm
Anodization: 10 nm to 20 μm
Air heat treatment: 10 nm to 20 μm
Oxygen plasma treatment: 10 nm to 20 μm
Acid treatment: 10 to 600 nm

When the oxide film layer 4 laminated by the above-described oxidation treatment is porous, various functions can be imparted to the metal material 1 by supporting various chemical substances in the pores. That is, as described above, the metal material 1 of the present embodiment further imparts antibacterial properties due to the implantation of fluorine ions to the surface 11 of the material, as well as antifouling property due to hydrophilicity and abrasion resistance in a water environment. However, by supporting a chemical substance on the porous oxide film layer 4, it is possible to impart a function derived from the chemical substance at the same time. For example, when the cobalt-chromium-molybdenum alloy is subjected to oxidation treatment by atmospheric heat treatment, the oxide film 4 can be made porous. Then, by injecting fluorine ions into the surface 41 of the porous oxide film layer 4 which is the surface 11 of the material and further supporting the bone-forming factor by impregnation, the surface 11 of the material having hydrophilicity has antibacterial properties. The bone formation promoting effect can be further imparted.

In order to further stabilize the oxide film layer 4, the oxide film layer 4 may be subjected to, for example, passivation treatment. As the passivation treatment, for example, the metal material 1 is immersed in a solution containing a strong oxidizing agent such as nitric acid, the metal material 1 is subjected to anodic polarization in a solution containing an oxidizing agent, and the metal material 1 is subjected to a low temperature heat treatment in oxygen. And the like.

The metal material 1 of the present embodiment described above can be manufactured, for example, as follows. First, the oxide film layer 4 is laminated on the surface 31 of the metal 3. Then, if necessary, cleaning is performed. The cleaning can be performed using, for example, an organic solvent. Examples of the organic solvent include ethanol and acetone. The organic solvents exemplified above may be used alone or in combination. The cleaning can also be performed by applying ultrasonic waves. After washing, for example, vacuum drying may be performed in a desiccator.

Next, fluorine ions are implanted into the surface 41 of the oxide film layer 4, which is the surface 11 of the material, to obtain the metal material 1. Examples of the fluorine ion implantation conditions include the following conditions.
Injection energy: 1 to 30 keV
Injection dose: 1×10 ^{15 to} 5×10 ¹⁷ cm ^-2

The metal material 1 of the present embodiment described above can be used, for example, as a material for an orthodontic wire, a metal fitting for dentures, and the like. The metal material 1 can also be used as a material for a biomedical implant such as a spinal device or a stent. When the metal material 1 is used for these members, the surface thereof has antibacterial and antifouling properties (self-cleaning effect) derived from the metal material 1, so that the growth of bacteria can be suppressed and the material is in a clean state. Can be easily maintained.

The metal material 1 is not limited to the materials such as the orthodontic wire described above, but can be used as a material for other members. Other members include, for example, frames of glasses, tableware that may be portable, a mouthpiece of a water bottle, a kitchen knife, a molded product in which powder of the metal material 1 is kneaded into a resin, an automatic cooking device, a toilet, a washlet. (Registered trademark), faucet, surgical instrument, injection needle and the like. When the metal material 1 is used for these members, the growth of bacteria can be suppressed and the clean state can be easily maintained, like the orthodontic wire described above.

Still another member that can use the metal material 1 is, for example, a living body implant including a sliding member. Examples of such biological implants include artificial joints such as hip joints, knee joints, ankle joints, and elbow joints. Specific examples of the sliding member include an artificial head and the like. When the metal material 1 is used for the biomedical implant provided with the sliding member, the surface has antibacterial properties, antifouling properties, abrasion resistance, etc. derived from the metal material 1, thus suppressing wear while maintaining cleanliness. can do. The same effect can be obtained, for example, when the metal material 1 is used for a line through which food flows, a tip of a catheter, a rotating shaft provided in the above-described automatic cooking device, an injection needle, and the like. The member that can use the metal material 1 is not limited to the illustrated members.

Although the preferred embodiments according to the present invention have been illustrated above, it goes without saying that the present invention is not limited to the above-described embodiments, and can be arbitrary without departing from the gist of the present invention.

For example, in the above-described embodiment, the metal material 1 includes the oxide film layer 4, but instead of this, the metal material 1 may not include the oxide film layer 4. The surface 11 of the material in the metal material 1 in this case is the surface 31 of the metal 3.

Further, in the above-described embodiment, the fluorine ion-implanted layer 2 is formed by ion implantation, but instead of this, the fluorine ion-implanted layer 2 can be formed by a treatment method other than ion implantation.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples.

<Production of metallic material>
First, the test pieces shown below were prepared. In addition, the thickness of the oxide film layer in the following test pieces is a value determined from microscopic observation of the cross section.
(Test pieces)
Metal: 3 mm thick cobalt-chromium-molybdenum alloy composed of ASTM F799 composition Oxide film layer: Main component is 2-5 nm thick (color tone: gray) chromium oxide laminated on the surface of metal by natural oxidation. Oxide layer

The above-mentioned test piece was molded into a disk shape having a diameter of 14 mm and a thickness of 1 mm, ultrasonically cleaned with ethanol and acetone, and vacuum dried in a desiccator.

Then, fluorine ions were implanted on the surface of the test piece. The implantation of fluorine ions was performed using an ion implantation device "SR-20" manufactured by Nisshin Ion Equipment Co., Ltd. The conditions for implanting fluorine ions are as follows.
Injection energy: 10 keV
Injection dose: 5×10 ¹⁵ cm ^-2

The test piece in which fluorine ions were injected was subjected to ultrasonic cleaning with ethanol and acetone, and vacuum dried in a desiccator to obtain a metal material.

[Comparative example]
<Production of metallic material>
A metal material was obtained in the same manner as in the above-described examples except that fluorine ions were not implanted on the surface of the test piece.

<Evaluation>
With respect to the obtained metal material, the contact angle of water with respect to the surface of the material and the coefficient of dynamic friction in water were measured. Each measuring method is as follows.

(Measurement method of contact angle of water to surface of material)
The contact angle of water with respect to the surface of the material was measured under the following conditions.
Measuring device: Surface contact angle measuring device "Drop Master DM300" manufactured by Kyowa Interface Science Co., Ltd.
Standard: ISO 15989
Solution: Ultrapure water Droplet volume: 1 μl
Retention time: 60 seconds Others: n=21 in the examples and n=9 in the comparative examples were measured, and the average value±standard deviation was calculated. The results are shown in the column of "contact angle of water" in Table 1.

(Measurement method of dynamic friction coefficient in water)
A cylindrical cross-linked polyethylene was fixed in water, and a dynamic friction coefficient was measured when a metal material was slid back and forth in water against the cross-linked polyethylene. The measurement conditions are as follows.
Measuring device: Shinto Scientific Co., Ltd. dynamic friction coefficient measuring device "Tribostation"
Solution: Ultrapure water Liquid temperature: 24°C
Sliding speed: 3000 mm/min Round trip distance: 25 mm
Number of reciprocations: 100 times Vertical load: 100g
Others: In Examples, n=7 and in Comparative Example, n=3, and the average value±standard deviation was calculated. The results are shown in Table 1 and FIG.

As is clear from Table 1, the examples in which fluorine ions were implanted on the surface of the material showed a result that the contact angle of water was significantly smaller than that of the comparative example in which fluorine ions were not implanted. This result shows that, in the example, the hydrophilicity is improved as compared with the comparative example, even though the surface of the material is implanted with fluorine ions, and the surface of the material into which the fluorine ion is implanted has hydrophilicity. ing. Further, as is clear from Table 1 and FIG. 2, the example showed a result that the coefficient of dynamic friction in water was smaller than that of the comparative example. Therefore, the abrasion resistance in the water environment due to the hydrophilicity also shows the surface of the material. It can be seen that it can be added to. Furthermore, in the examples, since fluorine ions were implanted into the surface of the material, it can be expected that antibacterial property is also imparted to the surface of the material.

For the examples, the fluorine atom concentration on the surface of the material was measured by SIMS. The measurement conditions are as follows.
Analytical apparatus: ULVAC-PHI Inc. , Japan secondary ion mass spectrometer "ADEPT-1010"
Primary ion species: Cs ⁺
Secondary ion polarity: Negative
Accelerating voltage: 2kV
Beam current: 50nA
Neutralizing gun: unused Raster size: 400 μm

As a result of measurement by SIMS, the fluorine atom concentration on the surface of the material was 2.6×10 ²⁰ atoms/cm ³ (about 0.3 atom %). Further, a fluorine ion-implanted layer having a thickness of about 40 nm was confirmed in the depth direction from the surface of the material. The maximum concentration of the fluorine ion-implanted layer was 8.6×10 ²⁰ atoms/cm ³ (about 1 atom %).

DESCRIPTION OF SYMBOLS 1 Metal material 11 Surface of material 2 Fluorine ion implantation layer 3 Metal 31 Surface of metal 4 Oxide coating layer 41 Surface of oxide coating layer A Depth direction D1 Thickness of fluorine ion implantation layer D2 Thickness of oxide coating layer

Claims (7)

A fluorine ion-implanted layer having a thickness of 30 to 800 nm is provided in the depth direction from the surface of the material, and the fluorine atom concentration on the surface of the material is 2.6×10 ²⁰ atoms/cm ³ or less, and The contact angle of water with the surface is 80° or less,
Metal,
Further comprising an oxide film layer laminated on the surface of the metal,
A metal material , wherein the surface of the material comprises the surface of the oxide film layer . The contact angle is 60 ° or less, a metal material according to claim 1. The fluorine ion implantation layer, CrF, CrF _2, CrF ₃ and CrF comprises at least one of _4, a metal material according to claim 1 or 2. The thickness of the oxide film layer is 2nm or more, a metal material according to any one of claims 1 to 3. Before Symbol thickness of the fluorine ion implantation layer is larger than the thickness of the oxide film layer, a metal material according to any one of claims 1 to 4. Metal, stainless steel or cobalt constituting the metal material - chromium - molybdenum alloy, a metal material according to any one of claims 1-5. Made of a metallic material according to any one of claims 1 to 6 bioimplant.

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