JP2020033592A - Amorphous carbon film and manufacturing method thereof - Google Patents

Abstract

To provide an amorphous carbon film capable of showing more excellent antibacterial action than hitherto even without using an antibacterial metal; and to provide a manufacturing method thereof.SOLUTION: There is provided an amorphous carbon film containing fluorine, which is an amorphous carbon film having a film surface modified by oxygen. A manufacturing method of the amorphous carbon film includes a film formation step for forming a fluorinated amorphous carbon film on a substrate by a plasma CVD method by using hydrocarbon gas and fluorocarbon gas, and an oxygen modification step for modifying, by oxygen, the surface of the fluorinated amorphous carbon film formed by an oxygen plasma treatment.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an amorphous carbon film capable of exhibiting an antibacterial action superior to conventional ones and a method for producing the same.

  In the field of medicine, medical technology such as replacement medicine is becoming more advanced, and with the advancement of medical treatment, there is a strong demand for the development of innovative medical materials that are inexpensive and safe. Under these circumstances, an amorphous carbon film, also called diamond-like carbon (DLC film), not only has high hardness, low friction and corrosion resistance, but also has excellent chemical stability and the same properties as the human body. Since it is composed of carbon and hydrogen and has excellent biocompatibility, it is particularly noted as a material meeting the above requirements, and is expected to be applied to medical equipment and medical devices.

  That is, materials such as metals and polymer materials are used for medical equipment and medical devices. However, when these materials enter the body, they are recognized as foreign substances, and there is a problem that a rejection reaction is induced. Therefore, as a method for preventing the induction of such rejection, it has been studied to modify the surface of the material, for example, by imparting biocompatibility by coating the surface of the material with an amorphous carbon film. The development of manufacturing technology for medical devices is becoming active. More specifically, in various medical devices such as stents, endoscopes, scalpel handles, and injection needles, and bioimplantable medical devices such as artificial joints, the surface of a material conventionally used is considered. It has been practiced to coat an amorphous carbon film.

  On the other hand, the surface of medical equipment and medical devices used in medical sites tends to become a hotbed of fast-growing bacteria and microorganisms, and when these infect humans, infectious diseases may occur. For this reason, it is preferable that the surface of the amorphous carbon film coated on the surface of the material also has an antibacterial action, and technology for imparting an antibacterial action to the amorphous carbon film is being actively developed. .

  Specifically, for example, in Patent Document 1, as shown in FIG. 8, fine particles of antibacterial metal formed on substrate 1 and having an antibacterial action selected from silver, copper, gold, platinum, zinc, and the like 3 is proposed. Patent Document 2 proposes exposing a part of a thin film of an antibacterial metal from a DLC film.

JP 2015-81370 A JP-A-10-110257

  However, in each of the above-mentioned technologies, an antibacterial effect is imparted by using an antibacterial metal, and thus there is a possibility that the cost may be significantly increased. In addition, its antibacterial effect is not sufficient for medical equipment and medical devices used in medical practice.

  Therefore, an object of the present invention is to provide an amorphous carbon film capable of exhibiting an excellent antibacterial action even without using an antibacterial metal, and a method for producing the same.

  The present inventor first increases the antibacterial effect by preventing bacteria and microorganisms from being implanted on the surface of the material, because bacteria and microorganisms grow by being implanted in water existing on the surface of the material. I thought I could. Then, as a specific means, it was considered effective to increase the water repellency of the amorphous carbon film, and fluorination of the amorphous carbon film was attempted. However, although a certain antimicrobial effect tended to be exhibited by fluorination, it was found that it was not yet sufficient.

  Then, next, various experiments and examinations were performed based on the fluorination of the amorphous carbon film, and the improvement of the antibacterial effect was evaluated. And it has been known that, while having antibacterial properties, it reduces water repellency while using oxygen, which is considered to be incompatible with fluorination, has found that a remarkable antibacterial action is exhibited. Was. That is, it was found that when the surface of the fluorinated amorphous carbon film was further modified with oxygen, a remarkable antibacterial action was exhibited.

  Further investigations revealed that the ratio F / C of the atomic composition percentage of fluorine F (at%) to the atomic composition percentage C of carbon (at%) on the film surface of the amorphous carbon film, F / C, and the atomic composition percentage of carbon The antibacterial effect is further improved by appropriately controlling either the ratio O / C of the atomic composition percentage O (at%) of oxygen to C (at%) or the contact angle of pure water on the surface of the amorphous carbon film. It has been found that it can be improved.

  Specifically, by setting the F / C to 0.05 or more, the O / C to 0.5 or more, or the contact angle to less than 30 °, the antibacterial property is further improved, and the film bonding method of JIS Z2801 is used. It has been found that the antibacterial activity value R, which is defined in (1), significantly exceeds 2.0, which is considered to have an antibacterial effect, and a remarkable antibacterial effect is surely exhibited.

  The improvement of the antibacterial effect was obtained because the antibacterial effect is not sufficiently exhibited only by modifying the non-fluorinated amorphous carbon film with oxygen. It is presumed that the antibacterial effect of oxygen modification was synergistically exhibited. Since conventional fluorination of amorphous carbon film is a technique performed to improve water repellency, it is surprising that such excellent antibacterial action was obtained by combining with oxygen modification that reduces water repellency. This is a good result.

The inventions described in claims 1 to 5 are based on the above findings. That is, the invention described in claim 1 is
An amorphous carbon film containing fluorine,
An amorphous carbon film characterized in that the film surface is modified with oxygen.

And the invention according to claim 2 is:
2. The amorphous carbon film according to claim 1, wherein the ratio F / C of the atomic composition percentage F of fluorine to the atomic composition percentage C of carbon on the film surface is 0.05 or more.

The invention described in claim 3 is:
3. The amorphous carbon film according to claim 1, wherein a ratio O / C of the atomic composition percentage O of oxygen to the atomic composition percentage C of carbon on the film surface is 0.5 or more. 4. is there.

The invention according to claim 4 is
The amorphous carbon film according to any one of claims 1 to 3, wherein a contact angle of the film surface with pure water is less than 30 °.

The invention described in claim 5 is
The amorphous property according to any one of claims 1 to 4, wherein a value of the antibacterial activity value R in an evaluation method by a film adhesion method defined in JIS Z2801 is 2.0 or more. Carbon film.

  If the amorphous hard carbon layer is too thin, there is a concern that the base material is exposed due to a film defect. On the other hand, if it is too thick, the adhesiveness is reduced due to the stress of the film. It is preferable that the film is formed to a thickness of 0.1 to 10 μm.

That is, the invention described in claim 6 is
The amorphous carbon film according to any one of claims 1 to 5, wherein the film has a thickness of 0.1 to 10 µm.

  The amorphous carbon film according to the present invention is formed by first forming a fluorinated amorphous carbon film on a substrate by a plasma CVD method using a hydrocarbon-based gas and a fluorocarbon-based gas as source gases. After that, it can be obtained by modifying the surface of the fluorinated amorphous carbon film with oxygen by oxygen plasma treatment.

That is, the invention described in claim 7 is:
The method for producing an amorphous carbon film according to any one of claims 1 to 6, wherein
A film forming step of forming a fluorinated amorphous carbon film on a substrate by a plasma CVD method using a hydrocarbon-based gas and a fluorocarbon-based gas,
An oxygen modification step of modifying the surface of the fluorinated amorphous carbon film formed by oxygen plasma treatment with oxygen.

  In addition, since the film formation by the plasma CVD method described above can be performed at a low temperature, not only metals and ceramics but also a lower heat-resistant temperature than metals and ceramics, but it is often used for medical equipment and medical devices. The used polymer material can be used for the base material. And, among polymer materials, it is more preferable to use general-purpose polystyrene (GPPS) from the viewpoint that it is inexpensive, has high versatility, and is easy to process for medical use.

That is, the invention described in claim 8 is:
The method according to claim 7, wherein the base material is a polymer material.

And the invention according to claim 9 is:
The method for producing an amorphous carbon film according to claim 8, wherein the polymer material is general-purpose polystyrene.

  As the above-described oxygen plasma treatment, for example, a low-temperature plasma treatment under reduced pressure or an atmospheric oxygen plasma treatment can be used. It is preferable because a high-density plasma can be directly irradiated to the object to be processed to perform quick processing, and the apparatus configuration is simple and inexpensive.

That is, the invention according to claim 10 is
The method for producing an amorphous carbon film according to any one of claims 7 to 9, wherein an atmospheric pressure oxygen plasma treatment is used for the oxygen plasma treatment.

  According to the present invention, it is possible to provide an amorphous carbon film capable of exhibiting an excellent antibacterial action even without using an antibacterial metal, and a method for producing the same.

It is a schematic diagram of a section of an amorphous carbon film of one embodiment of the present invention. It is a schematic diagram which shows the outline structure of a plasma CVD apparatus. It is a perspective view which shows the principal part of an atmospheric pressure plasma processing apparatus. It is a schematic diagram which shows an atmospheric pressure plasma processing method. It is a schematic diagram which shows the procedure of the antibacterial property evaluation test by a film bonding method. It is a figure showing the observation result of the sample surface after the antibacterial property evaluation test by the film adhesion method. It is a figure showing the observation result of the sample surface after the antibacterial property evaluation test by the film adhesion method. It is a schematic diagram of a section of a conventional antibacterial amorphous carbon film.

  Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

[1] Amorphous carbon film First, the amorphous carbon film according to the present embodiment will be described. FIG. 1 is a schematic diagram of a cross section of an amorphous carbon film (DLC film) according to an embodiment of the present invention. In FIG. 1, 1 is a base material, 4 is a fluorine-containing DLC film, and 5 is an oxygen-modified layer which is modified with oxygen on the fluorine-containing DLC film.

  As shown in FIG. 1, the amorphous carbon film according to the present embodiment is an amorphous carbon film containing fluorine by fluorination (fluorine-containing DLC film 4), and is formed on base material 1. ing. On the surface of the fluorine-containing DLC film 4, an oxygen-modified layer 5 modified with oxygen is formed.

  As described above, the present inventor has found that such a configuration can provide an amorphous carbon film exhibiting an excellent antibacterial action.

  The reason that the amorphous carbon film according to the present embodiment exerts an excellent antibacterial effect is presumed to be because the antibacterial effect by fluorination and the antibacterial effect by oxygen modification were synergistically exhibited as described above. Is done.

  Specifically, since fluorine imparts water repellency to the film, the implantation of bacteria can be suppressed. In addition, fluorine can inhibit bacterial glucose metabolism and thus can stop bacterial growth.

  Oxygen modified on the surface of the membrane is reduced by the action of chemical substances and oxidoreductase in bacteria attached to the membrane to become active oxygen, destroying nearby cell walls, cell membranes and intracellular enzymes. It is speculated that the growth of bacteria can be stopped and the growth of anaerobic bacteria caused by oxygen can be stopped.

  The antibacterial effect of the amorphous carbon film according to the present embodiment exerts a greater antibacterial effect on anaerobic bacteria, particularly facultative anaerobic bacteria such as Escherichia coli and Staphylococcus aureus.

  In the present embodiment, in order to ensure that a more remarkable antibacterial action is exhibited, the fluorine-containing DLC film 4 has a fluorine atomic composition percentage F (at%) with respect to a carbon atomic composition percentage C (at%) on the film surface. Is preferably 0.05 or more. The F / C can be determined based on the atomic composition percentage of each element on the surface of the DLC film measured using, for example, XPS (X-Ray Photoelectron Spectroscopy). In addition, there is no upper limit of F / C for surely exhibiting a more remarkable antibacterial action, but it is preferably 2.0 or less from the viewpoint of forming a film.

  The oxygen-modified layer 5 formed on the surface of the fluorine-containing DLC film 4 has a ratio O / C of the atomic composition percentage O (at%) of oxygen to the atomic composition percentage C (at%) of carbon of 0.5. It is preferable that it is above. Note that this O / C can also be obtained by measuring using XPS as in the case of the above-mentioned F / C. In addition, there is no upper limit of O / C for surely exhibiting a more remarkable antibacterial action, but it is preferably 3.0 or less from the viewpoint of exhibiting the effect of fluorine.

  Further, the contact angle of the surface of the amorphous carbon film with respect to pure water is preferably less than 30 °. By setting the contact angle to less than 30 °, it becomes hydrophilic and easily comes into contact with bacteria, so that a more sufficient antibacterial effect can be exhibited.

  The contact angle may be controlled by controlling F / C when forming the fluorine-containing DLC film 4 or controlling O / C when forming the oxygen-modified layer 5 or both. It can be done by doing.

  In the amorphous carbon film according to the present embodiment, by controlling the F / C, the O / C, and the contact angle as described above, the antibacterial activity value R defined in the film bonding method of JIS Z2801 can be reduced. It can be set to 2.0 or more (R ≧ 2.0), which is considered to be effective, and more sufficient antibacterial properties can be secured as a medical device or a medical device. The antibacterial activity value R is more preferably 2.2 or more, even more preferably 2.5 or more.

  In the present embodiment, the substrate 1 is not particularly limited, and a material known as a material for various medical devices and medical devices, such as a polymer material, a metal, and a ceramic, can be used. Specific polymer materials include, for example, polystyrene, polyurethane, polyethylene, polypropylene, polyimide, polyamide, silicon, rubber, and the like. Among these, medical treatment is inexpensive, versatile, and easy to process. Considering this point, general-purpose polystyrene is preferable. Examples of the metal include titanium, a titanium alloy, stainless steel, a cobalt chromium molybdenum alloy, a cobalt chromium alloy, and alumite-treated aluminum. In addition, examples of the ceramics include alumina and zirconia.

[2] Method for Manufacturing Amorphous Carbon Film Next, a method for manufacturing the amorphous carbon film according to the present embodiment will be described.

  The amorphous carbon film according to the present embodiment forms a fluorinated amorphous carbon film on a substrate by a plasma CVD method using a hydrocarbon-based gas and a fluorocarbon-based gas, and then performs an oxygen plasma treatment. It can be manufactured by modifying the surface of a fluorinated amorphous carbon film with oxygen. Hereinafter, a film forming step of forming a fluorinated amorphous carbon film and an oxygen modifying step of modifying with oxygen will be described in this order.

1. FIG. 2 is a schematic diagram showing a schematic configuration of a plasma CVD apparatus. 2, reference numeral 11 denotes a plasma CVD apparatus, 12 denotes a chamber (film formation chamber), 12a denotes a gas introduction port, 12b denotes a gas outlet, 13 denotes a cathode, and 14 denotes an anode. , 15 are high frequency power supplies.

The chamber 12 is connected to a supply source of an etching H ₂ gas and a source gas at a gas introduction port 12a, and is connected to a vacuum pump at a gas outlet. The cathode 13 is connected to a high-frequency power supply having a frequency of 13.56 MHz. On the other hand, the anode 14 and the chamber 12 are grounded.

First, after setting the substrate 1 on the cathode 13, the inside of the chamber 12 is evacuated until a predetermined degree of vacuum is reached. Thereafter, the H ₂ gas is supplied from the gas introduction port 12a and the high frequency power supply 15 is operated. As a result, H ₂ plasma is generated in the chamber 12, and the surface of the substrate 1 can be etched and cleaned with the H ₂ plasma.

  Next, a raw material gas obtained by mixing a hydrocarbon gas and a fluorocarbon gas at a predetermined mixing ratio is supplied from the gas introduction port 12a. Then, a high-frequency power source is applied, and the base material 1 is irradiated with dissociated molecules and ions of the source gas generated by turning the source gas into plasma. Thereby, a fluorine-containing DLC film can be formed on the substrate 1.

  In forming the fluorine-containing DLC film, the F / C can be controlled to a desired value by adjusting the mixing ratio between the hydrocarbon gas and the fluorine gas in the source gas.

  In the present embodiment, the hydrocarbon gas is not particularly limited as long as it is a hydrocarbon gas capable of supplying carbon, but methane gas, ethane gas, acetylene gas, and the like are preferable from the viewpoint of being inexpensive and easily available.

  The fluorocarbon gas is not particularly limited as long as it is a fluorocarbon gas capable of supplying fluorine. However, from the viewpoint of being cheap and easily available, ethane fluoride gas, methane fluoride gas, or the like is preferable.

  Then, as described above, the amorphous hard carbon layer may be exposed on the base material from the viewpoint that the base material is exposed due to a film defect if the thickness is too thin, and that the adhesiveness is reduced due to the stress of the film if the thickness is too large. It is preferable that the film is formed to a thickness of 0.1 to 10 μm. The thickness of the DLC film can be controlled, for example, by adjusting the film formation time.

  In this embodiment mode, the plasma CVD method is a method capable of forming a DLC film at a low temperature, and thus is made of a polymer material such as polystyrene (PS) having a heat-resistant temperature of 70 to 90 ° C. It is possible to form a film on a substrate having a low heat-resistant temperature.

2. Oxygen Modification Step After forming the fluorine-containing DLC film 4, the surface of the fluorine-containing DLC film 4 is subjected to oxygen plasma treatment to form the oxygen-modified layer 5. O / C can be controlled to a desired ratio, for example, by adjusting the processing time by oxygen plasma.

  Specific examples of the oxygen plasma treatment method include, for example, a low-temperature plasma treatment method under reduced pressure and an atmospheric pressure oxygen plasma treatment. Among them, as described above, the atmospheric pressure oxygen plasma treatment is performed under the atmospheric pressure. It is preferable because a high-density plasma at a low temperature can be directly irradiated to the object to be processed so that quick processing can be performed, and the apparatus configuration is simple and low-cost.

  Various devices such as a remote type and a jet type have been developed as an atmospheric pressure plasma processing apparatus, and in the present embodiment, these known apparatuses can be used. It is particularly preferable because it can be processed at a low temperature without causing damage.

  FIG. 3 is a perspective view showing a main part of the atmospheric pressure plasma processing apparatus, and FIG. 4 is a schematic view showing an atmospheric pressure plasma processing method. Here, an atmospheric pressure plasma processing apparatus of a damage-free multi-plasma jet type is described as an atmospheric pressure plasma processing apparatus. 3 and 4, reference numeral 21 denotes an atmospheric pressure plasma nozzle, reference numeral 22 denotes a stage, and reference numeral 23 denotes a sample stage. The atmospheric pressure plasma nozzle 21 is connected to a plasma generator (not shown) having a pulse power supply on the order of kHz (up to 20 kHz). W is a sample in which a fluorine-containing DLC film is formed on the surface of a substrate.

  The sample W is placed on a sample table 23 placed on the stage 22 along the x direction. The atmospheric pressure plasma nozzle 21 can move in the x direction and the z direction (vertical direction), and the stage 22 can move in the y direction (a direction perpendicular to the x direction).

  Then, after moving the stage 22 in the y-direction so that the sample W is located directly below the atmospheric pressure plasma nozzle 21, the interval between the surface of the sample W and the tip of the nozzle becomes a suitable interval for processing. The atmospheric pressure plasma nozzle 21 is moved in the z direction. Thereafter, the power supply is operated to generate oxygen plasma. Then, while irradiating the generated oxygen plasma from the atmospheric pressure plasma nozzle 21 toward the sample W, the atmospheric pressure plasma nozzle 21 is moved in the x direction at a predetermined speed to scan the surface of the sample W. Thereby, the surface of the DLC film is subjected to the oxygen plasma treatment, and the oxygen-modified layer 5 is formed.

  Hereinafter, the present invention will be described more specifically based on examples.

[1] Experiment 1
1. Experimental Method As Experiment 1, two types of DLC films (1.0 μm thick) containing and not containing fluorine were formed on a substrate by using general-purpose polystyrene (GPPS) as a substrate. For each of them, test specimens coated with two types of DLC films, two types with and without oxygen modification, were prepared, and an experiment for evaluating the antibacterial properties of each DLC film was performed.

(1) Preparation of DLC Film (a) Formation of Fluorine-Containing DLC Film After the base material was etched using H ₂ plasma, a fluorine-containing DLC film was formed using a high-frequency plasma CVD method. The forming conditions are shown below.
Source gas: mixed gas of methane (CH ₄ ) and ethane hexafluoride (C ₂ F ₆ )
(Mixing ratio: CH ₄ : C ₂ F ₆ = 4: 6)
Reaction pressure: 13.3 GPa
Applied power: 540W
Film formation time: 30 min
Substrate: GPPS (size: 50 mm long x 50 mm wide x 10 mm thick)

(B) Formation of Fluorine-Free DLC Film A fluorine-free DLC film was formed under the same conditions as the above-described formation of the fluorine-containing DLC film, except that only methane (CH ₄ ) was used as the source gas.

(2) Oxygen modification Each of the formed fluorine-containing DLC film and the fluorine-free DLC film was divided into two, and one of them was subjected to atmospheric pressure plasma treatment to perform oxygen modification on the surface, and the other was not subjected to oxygen modification. . The atmospheric pressure plasma processing apparatus and processing conditions used for oxygen modification are shown below.
Processing equipment: damage-free multi-plasma jet equipment Reactive gas: oxygen (O ₂ )
Reaction gas volume: 10 L / min
Processing time: 15min

2. Evaluation (1) Evaluation Items and Evaluation Method (a) F / C: The atomic composition percentage F of fluorine and the atomic composition percentage C of carbon were measured on the DLC film surface of the prepared test piece using the XPS method, and from the measurement results. F / C was determined. The XPS measurement was performed using a damage-free multi-plasma jet device (JPS-90100MC) manufactured by Plasma Concept Tokyo Co., Ltd. under the conditions of X-ray: MgKα ray, voltage: 10.0 kv, and current: 10 mA. .

(B) O / C: The atomic composition percentage O of oxygen and the atomic composition percentage C of carbon were measured on the surface of the DLC film of the prepared test piece by the XPS method, and O / C was obtained from the measurement results.

(C) Contact angle: The angle between the surface of the DLC film of the test piece and the surface of the sample when a droplet of pure water was brought into contact with the surface of the test piece and dropped was measured.

(D) Antibacterial properties: The antibacterial activity value R was determined using an evaluation method based on a film bonding method specified in JIS Z2801: 2010. As the bacterial species, two types of Escherichia coli (NBRC-12732) and Staphylococcus aureus (NBRC-3972) were used.

Specifically, evaluation was performed according to the procedure shown in FIG. That is, after putting the prepared 50 × 50 mm test pieces (Experimental Examples 1 to 4) into a sterilized petri dish, 0.4 mL of a bacterial solution containing about 1.0 × 10 ⁵ test bacteria was applied to the center of the test piece. And coated with a polyethylene (PE) film cut into 40 × 40 mm. Then, this petri dish was placed in an environment of 35 ° C. and a relative humidity of 90% and cultured for 24 hours. Thereafter, the test bacteria were washed out, placed in a petri dish, and the number of viable bacteria per 1 cm ² was measured. The antibacterial activity value R (the average value of n = 3) was determined from the measurement results of the prepared test piece and the control test piece using the following equation. The unprocessed test piece (control) was prepared by preparing a test piece (uncoated) using only the base material (GPPS) and not provided with a DLC film, and culturing the same.
Antibacterial activity value R = log ₁₀ A / B
A: Viable cell count after culturing of unprocessed test piece (control)
B: Viable cell count after culturing of the target sample

  Further, the petri dish after the film adhesion test was visually observed.

(2) Evaluation results (a) Evaluation results of F / C, O / C and contact angle Table 1 shows the evaluation results of F / C, O / C and contact angle.

(B) Results of antibacterial property test Tables 2 and 3 show the results of the antibacterial property test. The antibacterial properties were “excellent” when the antibacterial activity value R ≧ 2.5, “good” when 2.5> R ≧ 2.2, and 2.2 when R ≧ 2.0. Is described as “OK”, and the case of R <2.0 is described as “None”. 6 (Escherichia coli) and FIG. 7 (Staphylococcus aureus) show the observation results of the petri dish after the film adhesion test.

  As shown in Table 2, the antibacterial activity against Escherichia coli showed a value of 2.0 or more, which is considered to be antibacterial only in Example 1 containing fluorine and oxygen-modified.

  Then, as shown in FIG. 6, in Experimental Example 1-A (FIG. 6 (a)), white spots indicating that E. coli had been killed were observed over the entire area. Experimental Example 2-A containing no fluorine (FIG. 6 (b)), Experimental Example 3-A containing fluorine but not oxygen-modified (FIG. 6 (c)), oxygen containing no fluorine In the case of Experimental Example 4-A (FIG. 6 (d)), which was not modified, white spots were not observed for E. coli.

  As shown in Table 3, the antibacterial activity against Staphylococcus aureus was 2.0 or more, which was considered to be antibacterial only in Experimental Example 1 containing fluorine and oxygen-modified as in the test for Escherichia coli. The value was shown.

  Then, in the antibacterial property test of Staphylococcus aureus, the killed bacteria become transparent unlike Escherichia coli, but as shown in FIG. 7, in Experimental Example 1-B (FIG. 7A), the killed bacteria are killed. A transparent region indicating that the measurement was performed was observed over the entirety, while Experimental Example 2-B (FIG. 7B), Experimental Example 3-B (FIG. 7C), and Experimental Example 4-B (FIG. 7 (d)), white spots were observed.

  As described above, according to the present embodiment, it was confirmed that the fluorine-containing and oxygen-modified DLC membrane had an excellent antibacterial effect on both Escherichia coli and Staphylococcus aureus. On the other hand, a DLC film containing fluorine but not modified with oxygen, a DLC film modified with oxygen but not containing fluorine, and a DLC film containing no fluorine and not modified with oxygen have antibacterial activity values. R was significantly lower than 2.0, and it was confirmed that a remarkable antibacterial effect was not obtained when only one of fluorine-containing and oxygen-modified was used and when fluorine-free and oxygen-modified was not used. .

[2] Experiment 2
1. Experimental Method As an experiment 2, an experiment was conducted to examine a preferable range of F / C and O / C for obtaining sufficient antibacterial property in an amorphous carbon film obtained by modifying a fluorine-containing DLC with oxygen. Test pieces shown in Table 4 were prepared in the same manner as in Experiment 1 except for the mixing ratio of the source gases in the film formation by plasma CVD and the treatment time for oxygen modification, and evaluated in the same manner as in Experiment 1. In order to set the F / C to 0.1, 0.05, and 0.04, respectively, the mixing ratio of methane: 6 hexafluoroethane at the time of film formation using plasma CVD was 4: 5, 2: 5, In order to set the O / C ratio to 1.0, 0.5, and 0.4, respectively, the oxygen modification treatment time was set to 15 min, 7.5 min, and 5.5 min.

2. Evaluation results The test results are shown in Tables 5 and 6.

  From the results shown in Tables 5 and 6, it was found that good antibacterial properties can be obtained when F / C is 0.05 or more or O / C is 0.5 or more.

  As described above, the present invention has been described based on the embodiments, but the present invention is not limited to the above embodiments. Various changes can be made to the above embodiment within the same and equivalent scope as the present invention.

DESCRIPTION OF SYMBOLS 1 Substrate 2 DLC film 3 Antimicrobial metal fine particle 4 Fluorine containing DLC film 5 Oxygen modification layer 11 Plasma CVD device 12 Chamber 12a Gas introduction port 12b Gas outlet 13 Cathode 14 Anode 15 High frequency power supply 21 Atmospheric pressure plasma nozzle 22 Stage 23 Sample table W Sample

Claims (10)

An amorphous carbon film containing fluorine,
An amorphous carbon film, wherein the film surface is modified with oxygen.   The amorphous carbon film according to claim 1, wherein a ratio F / C of the atomic composition percentage F of fluorine to the atomic composition percentage C of carbon on the film surface is 0.05 or more.   3. The amorphous carbon film according to claim 1, wherein the ratio O / C of the atomic composition percentage O of oxygen to the atomic composition percentage C of carbon on the film surface is 0.5 or more.   The amorphous carbon film according to any one of claims 1 to 3, wherein a contact angle of the film surface with pure water is less than 30 °.   The amorphous property according to any one of claims 1 to 4, wherein a value of the antibacterial activity value R in an evaluation method by a film adhesion method defined in JIS Z2801 is 2.0 or more. Quality carbon membrane.   The amorphous carbon film according to any one of claims 1 to 5, wherein the film has a thickness of 0.1 to 10 µm. The method for producing an amorphous carbon film according to any one of claims 1 to 6, wherein
A film forming step of forming a fluorinated amorphous carbon film on a substrate by a plasma CVD method using a hydrocarbon-based gas and a fluorocarbon-based gas,
An oxygen modification step of modifying the surface of the fluorinated amorphous carbon film formed by oxygen plasma treatment with oxygen.   The method according to claim 7, wherein the base material is a polymer material.   The method for producing an amorphous carbon film according to claim 8, wherein the polymer material is general-purpose polystyrene.   The method for producing an amorphous carbon film according to any one of claims 7 to 9, wherein an atmospheric pressure oxygen plasma treatment is used for the oxygen plasma treatment.