JP2021138987A - Inner surface-coated tube - Google Patents

Abstract

To provide an inner surface-coated tube that has a polymer-like carbon film, having a carboxyl group, formed uniformly in an inner surface.SOLUTION: An inner surface-coated tube 100 comprises a flexible tube body 101 which is 200 mm long or more, and a polymer-like carbon film 102 which is formed on the entire inner surface of the tube body 101. The polymer-like carbon film 102 has a rate of 12-25 at% of oxygen adjacent carbon to all carbon on a top surface, and a variation coefficient of 18% or less in rate of the oxygen adjacent carbon to all the carbon at three or more points, each 50 mm apart of the tube body, at least part of the oxygen adjacent carbon forming a carboxyl group.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to an inner coating tube and a method for manufacturing the same.

Flexible resin tubes are used in various fields because they are easy to handle, and in the fields of medicine and food, resin tubes are also used for transferring various liquids. Depending on the liquid flowing in the resin tube, the interaction between the components in the liquid and the resin tube may become a problem. In particular, in the case of a tube through which blood flows, there is a problem that the resin tube is blocked by the action of various blood components.

In order to avoid blockage of the resin tube, it has been studied to modify the inner surface of the resin tube to reduce the interaction between the resin tube and the blood component. In the case of a flat plate or a bottle-like shape, the surface can be easily modified by a so-called dry method such as plasma irradiation. However, in the case of a long tube, it is difficult to modify the inside by the dry method, and the surface is modified by a wet method such as coating. However, surface modification by the wet method has many problems in terms of time and uniformity, and surface modification by the dry method is required.

As a surface modification by a dry method, it has been studied to generate a hydrocarbon plasma in a resin tube to form a diamond-like carbon (DLC) film on the inner surface of the resin tube (for example, Patent Document 1). reference.).

Japanese Patent No. 65067887

However, the DLC film formed in the conventional resin tube is formed by CC bonds and CH bonds, and is not sufficient in terms of biocompatibility.

An object of the present disclosure is to make it possible to more uniformly form a coating having excellent biocompatibility on the inner surface of the resin tube.

The inner surface coating tube of the present disclosure includes a flexible tube body having a length of 200 mm or more and a polymer-like carbon film formed on the entire inner surface of the tube body, and the polymer-like carbon film is adjacent to oxygen on the surface. The ratio of carbon to total carbon is 12 at% or more and 25 at% or less, and the fluctuation coefficient of the ratio of oxygen adjacent carbon to total carbon at three or more points 50 mm apart from the tube body is 18% or less, and oxygen. At least a part of the adjacent carbon forms a carboxyl group.

The inner surface coating tube of the present disclosure uniformly has a polymer-like carbon film having a carboxyl group on the inner surface, and the biocompatibility of the inner surface of the tube can be further improved.

It is sectional drawing which shows the inner surface covering tube which concerns on one Embodiment. It is a schematic diagram which shows an example of a film forming apparatus. It is a figure which shows the C1s peak of each tube by comparison.

As shown in FIG. 1, the inner surface covering tube 100 of the present embodiment includes a tube main body 101 and a polymer-like carbon film 102 formed on the entire inner surface of the tube main body 101.

The tube body 101 is a seamless and flexible tube. The length of the tube body 101 is not particularly limited, but from the viewpoint of being used in a medical device such as a catheter, the length of the tube body 101 is preferably 100 mm or more, more preferably 200 mm or more. From the viewpoint of ease of inner surface coating, the length of the tube body 101 is preferably 5000 mm or less, more preferably 2000 mm or less. The thickness of the tube body 101 is not particularly limited, but the inner diameter of the tube body 101 is preferably 0.8 mm or more, more preferably 1.0 mm or more, preferably 1.0 mm or more, from the viewpoint of ease of inner surface coating and use in various medical devices. Is 10 mm or less, more preferably 8 mm or less, still more preferably 6 mm or less.

The tube body may be flexible as long as it can be wound into a cylindrical shape, and the material thereof is not particularly limited. For example, polyvinyl chloride, polyurethane, polyethylene, polypropylene, polyimide, polyethylene vinyl acetate (EVA), polyamide elastomer, polyurethane elastomer, biodegradable polymers such as polylactic acid and its copolymers, cyclic polyolefin, polyethylene terephthalate, fluororesin, The tube may be made of polycarbonate, polysulfone, latex rubber, acrylic resin, silicone, stretched polytetrafluoroethylene (ePTFE), unstretched polytetrafluoroethylene, or the like.

The polymer-like carbon film 102, which is an inner coating, is a carbon-containing film that is being standardized by the International Organization for Standardization (ISO). In the present embodiment, the carbon atom contained in the polymer-like carbon film 102 is a carbon adjacent carbon forming a carbon-carbon (CC) bond and hydrogen forming a carbon-hydrogen (CH) bond. It contains adjacent carbons and oxygen adjacent carbons forming a carbon-oxygen (CO) bond. The CC bond and the CH bond include those having sp2 bond and those having sp3 bond. At least a part of the CO bond forms a carboxyl group.

The ratio of oxygen-adjacent carbon atoms to the total carbon atoms on the surface of the polymer-like carbon film 102 is 12 at% or more, preferably 15 at% or more, 25 at% or less, and preferably 23 at% or less throughout the entire tube. By setting the ratio of oxygen-adjacent carbon atoms to such a value, biocompatibility can be improved while maintaining the physical properties of polymer-like carbon. The ratio of oxygen-adjacent carbon atoms can be determined by the X-ray photoelectron spectroscopy (XPS) method as shown in Examples.

The film thickness of the polymer-like carbon film 102 on the inner wall of the tube body 101 is not particularly limited, but is preferably 3 nm or more, more preferably 10 nm or more, from the viewpoint of reducing the friction coefficient of the inner surface of the catheter. Further, from the viewpoint of preventing peeling and the like, it is preferably 150 nm or less, more preferably 100 nm or less.

Polymers like carbon forming the tube body 101 in the hardness (H _IT) is preferably from the viewpoint of ensuring the followability to deformation of the tube 3GPa, more preferably at most 1 GPa. Further, from the viewpoint of ensuring the function as a polymer-like carbon film, it is preferably 0.1 GPa or more, more preferably 0.2 GPa or more.

The polymer-like carbon film 102 formed on the inner surface of the tube body 101 is uniformly formed throughout the inside of the tube. Specifically, the coefficient of variation (CV: standard deviation / average value x 100%) of the ratio of oxygen-adjacent carbons in the polymer-like carbon film at three or more points separated from each other by 50 mm or more is preferably 18% or less. More preferably, it is 15% or less.

Further, the polymer-like carbon film 102 is formed to have a constant thickness throughout the inside of the tube. Specifically, the coefficient of variation of the thickness of the polymer-like carbon film 102 at three or more points separated from each other by 50 mm or more is preferably 15% or less, more preferably 12% or less. The thickness of the polymer-like carbon film 102 can be determined by microspectroscopy as shown in Examples.

The inner surface covering tube 100 of this embodiment can be formed by using the following film forming apparatus. FIG. 2 shows a film forming apparatus for the polymer-like carbon film 102. The film forming apparatus 200 has a chamber 201 inside which houses a tube body 101 which is a long thin tube to be formed. The vacuum exhaust unit 210 and the gas supply unit 215 for supplying gas into the chamber 201 are connected to the chamber 201, and the internal pressure can be adjusted. Further, a power supply unit 220 for supplying electric power is connected, and plasma can be generated in the chamber 201.

In the present embodiment, the vacuum exhaust unit 210 has a vacuum pump 212 and a valve 213. In the present embodiment, the gas supply unit 215 has a plurality of cylinders 216, a flow path switching unit 218 for switching the cylinders 216, and a mass flow controller 217. In the present embodiment, the gas supply unit 215 has a flow path switching unit 218, and can switch between the supply of the film-forming gas and the supply of the surface modification gas. In the present embodiment, the power supply unit 220 has a voltage generator 221 and an amplifier 222, and applies an AC voltage between the discharge electrode 225 and the counter electrode. The counter electrode is a ground electrode and serves as an inner wall of the chamber 201.

One end of the tube body 101 arranged in the chamber 201 is arranged at the position of the discharge electrode 225, and the other end is in an open state. After depressurizing the inside of the chamber 201, a film-forming gas containing a hydrocarbon is supplied from the gas supply unit 215, and an AC voltage is applied between the discharge electrode 225 and the inner wall of the chamber 201 which is a counter electrode. The application of the AC voltage raises the temperature around the discharge electrode 225. As a result, the pressure inside the tube body 101 becomes slightly lower than that outside the tube body 101, and hydrocarbon plasma is generated in the vicinity of the discharge electrode 225. Since the other end of the tube body 101 is released, the generated plasma moves in the tube body 101 toward the released end side, and plasma is generated in the entire tube body 101. As a result, an unmodified polymer-like carbon film is formed on the inner wall surface of the tube body 101.

Next, the gas supply unit 215 is switched to supply a surface modification gas containing oxygen, and the gas flowing in the tube body 101 is replaced with the surface modification gas from the film forming gas. After that, an AC voltage is applied between the discharge electrode 225 and the inner wall of the chamber 201 which is the counter electrode to generate oxygen plasma in the tube body 101. As a result, a carboxyl group is introduced into the unmodified polymer-like carbon film, and a polymer-like carbon film is obtained.

From the viewpoint of sufficiently purging the chamber 201 in the raw material gas, it is preferable to reduce the pressure to temporarily 1 × 10 ^-3 Pa~5 × 10 ^-3 approximately Pa in the chamber before deposition. As the hydrocarbon contained in the raw material gas, methane, ethane, propane, butane, ethylene, acetylene, benzene and the like used in the usual CVD method can be used, and methane is preferable from the viewpoint of handling. Further, as the raw material gas, an organosilicon compound such as tetramethylsilane or an oxygen-containing organosilicon compound such as hexamethyldisiloxane can be vaporized and used. The raw material gas can be supplied after being diluted with an inert gas such as argon, neon or helium, if necessary, and is preferably diluted with argon from the viewpoint of handling. When diluting, the ratio of the hydrocarbon to the inert gas is preferably about 10: 1 to 10: 5.

From the viewpoint of uniformly forming an unmodified polymer-like carbon film in the tube body, the pressure in the chamber 201 is preferably about 5 Pa to 200 Pa while the film-forming gas is supplied. The flow rate of the film-forming gas can be about 50 sccm to 200 sccm.

The bias voltage applied to the discharge electrode 225 at the time of film formation can be about 1 kV to 20 kV. It is preferably 10 kV or less from the viewpoint of avoiding damage to the discharge electrode and temperature rise. The frequency of the AC voltage is preferably about 1 kHz to 50 kHz. The AC voltage is preferably a pulse bias applied intermittently from the viewpoint of suppressing the temperature rise. When the alternating current is a burst wave, the pulse repetition frequency is preferably about 3 pps to 50 pps. The tube temperature can be set to 200 ° C. or lower by setting the pulse repetition frequency to about 30 pps or less, although it depends on the inner diameter of the tube body 101, the film forming time, the AC applied voltage, and the like. If you want to increase the film formation speed, you can increase the pulse repetition frequency, and if you want to suppress the temperature rise, you can decrease the pulse repetition frequency.

It is preferable to apply an offset negative voltage to the discharge electrode 225 in order to stabilize the discharge and obtain the adhesion of the unmodified polymer-like carbon film. The offset voltage can be about 0 to 3 kV.

The film formation time may be set so that the required film thickness can be obtained, and the optimum value may be selected according to the film formation conditions such as the inner diameter of the tube body 101, the AC voltage, and the pulse repetition frequency. From this point of view, it is preferably 60 minutes or less, more preferably 30 minutes or less, and further preferably 10 minutes or less.

When surface modification is to the tube body 101 in the surface modifying gas, be reduced to 1 × 10 ^-3 Pa~5 × 10 ^-3 approximately Pa once stopping the supply of the film forming gas preferable. After that, it is preferable to supply the surface reforming gas at a flow rate of about 50 sccm to 200 sccm to generate oxygen plasma with the pressure in the chamber 201 set to about 5 Pa to 200 Pa.

The surface reforming gas can be pure oxygen, but can be supplied by diluting it with an inert gas such as argon, neon, or helium, if necessary. When diluted, the ratio of pure oxygen to the inert gas is preferably about 10: 1 to 10: 5.

Conditions such as the bias voltage applied to the discharge electrode 225 at the time of surface modification can be the same as in the case of film formation. The treatment time with oxygen plasma is preferably 0.5 seconds or more, more preferably 1 second or more from the viewpoint of sufficient modification, and preferably 6 seconds or less from the viewpoint of suppressing decomposition of the unmodified polymer-like carbon film. It is preferably 5 seconds or less.

The entire inner surface of the surface-coated tube of the present disclosure is uniformly coated with a polymer-like carbon film containing a carboxyl group, and is used for endovascular treatment / inner treatment of artificial blood vessels of various diameters, covered stents, tube stents, catheters, sheaths, etc. Cylindrical resin structures related to endoscopic treatment (all tubular resin structures involved in the treatment of blood vessels, urinary tracts, bile ducts / pancreatic vessels, abdominal cavity, thoracic cavity, etc., for the purpose of temporary or long-term indwelling in vivo ), An in vitro blood circulation circuit such as an artificial cardiopulmonary circuit and a tube circuit during dialysis, and an infusion circuit, etc., which can be used for all medical devices using a tubular resin structure that is not intended to be placed in the body. Further, it can be used not only in medical devices but also in various fields where smoothness and hydrophilicity of the inner surface are required.

<Device>
A carbonaceous film was formed on the inner wall surface of the sample by the film forming apparatus shown in FIG. The chamber 201 is a stainless steel container having a diameter of 200 mm and a length of 500 mm. A vacuum exhaust unit 210 and a gas supply unit 215 are connected to the chamber 201, and the power supply unit 220 is composed of a voltage generator 221 (SG-4104 manufactured by IWATSU) and an amplifier 222 (HVA4321 manufactured by NF Corporation). The discharge electrode 225 was a stainless steel electrode having a diameter of 6 mm and a length of 70 mm. The gas supply unit 215 has a methane gas cylinder and an oxygen cylinder as the cylinder 116, and is configured to be able to switch and supply these. The pressure in the chamber 201 was adjusted by controlling the opening degree of the valve and the amount of gas supplied.

<Film formation>
A film was formed on a silicon tube having an inner diameter of 4 mm and a length of 500 mm. The film-forming gas was CH ₄ , the flow rate was 96.2 ccm (room temperature), and the pressure in the chamber was 39.06 Pa. The bias voltage at the time of film formation was 5 kV, and the frequency was 10 kHz. The AC voltage was applied intermittently for 20 minutes so that the pulse repetition frequency was 10 pps or 30 pps. At the time of film formation, an offset of 2 kV was applied by an amplifier.

<Surface modification>
After forming an unmodified polymer-like carbon film, the gas supplied into the tube was switched to a surface-modified gas, and plasma was generated for 3 seconds. The surface reforming gas was oxygen gas. The plasma generation conditions were the same as those for film formation.

<Analysis of membrane composition>
The composition of the polymer-like carbon film was evaluated by X-ray photoelectron spectroscopy (XPS) measurement. JPS-9200S manufactured by JEOL Ltd. was used for XPS measurement. The conditions for XPS measurement were that the detection angle with respect to the sample was 90 degrees, Mg was used as the X-ray source, and the X-ray irradiation energy was 100 W.

From the intensity ratios of O1s peak, C1s peak and Si2p peak obtained by narrow scan, a judgment fee analysis was performed using a relative sensitivity coefficient, and the abundance ratios of carbon atoms, oxygen atoms and silicon atoms on the film surface were determined. In addition, the C1s peak is separated into four components C-C, C-H, C-O, and O = CO by fitting, and the area strength of C-O and O = CO is the ratio of oxygen-adjacent carbon. The area strength of CC was defined as the ratio of carbon adjacent carbon, and the area strength of CH was defined as the ratio of hydrogen adjacent carbon, and the ratio of oxygen adjacent carbon to all carbon atoms was calculated from these ratios. A Gauss-Lorentz function (ratio 0.7) was used for fitting. It is assumed that CC and CH have two peaks of 284.7 eV and 285.4 eV, the CO peak is 286.5 eV, and the O = CO peak is 288.3 eV. Waveform separation was performed.

<Measurement of film thickness>
The film thickness of the polymer-like carbon film formed on the inner surface of the tube was calculated from the reflectance of the inner surface of the tube measured by a microspectroscopy (Otsuka Electronics Co., Ltd., OPTM-F2). The objective lens used was 5 times visible refraction, and the spot diameter was φ40 μm. The reflectance of the inner surface of the tube was measured in a state where the inner surface was exposed by cutting the tube.

A model is constructed in which a roughness layer exists on the surface of the silicone tube, and the polymer-like carbon film penetrates into the roughness layer to form a roughness layer. The film thickness of was calculated. The refractive index n and the disappearance coefficient k of the silicone tube as the base material were calculated by curve fitting by applying the EMA_mix model.

<Measurement of surface roughness (Ra)>
The arithmetic mean surface roughness (Ra) was measured using an image taken by a white interferometer (NewView5320, manufactured by Zygo). The shooting magnification was set to 100 times, and as background removal processing, the substrate shape was removed by Cylinder and the waviness component was removed by FFT auto High pass processing. Ra was measured in the line data (length 50 μm) of the flat portion excluding the crack and the defective portion.

<Measurement of film hardness>
_{The hardness (HIT} ) of the polymer-like carbon film was measured by the nanoindentation method. A silicon wafer cut to a predetermined size was placed in the tube, polymer-like carbon was formed on the surface of the silicon wafer together with the inner surface of the tube, and the hardness of the polymer-like carbon film on the surface of the silicon wafer was measured. A nanoindenter (Nanoindenter TI950, manufactured by Hysitron) was used for the measurement.

<Measurement of contact angle>
The contact angle of the polymer-like carbon film surface with water was measured using a contact angle measuring device (DropMaster500, Kyowa Interface Science Co., Ltd.). The tube was cut to expose the inner surface, and the measurement was performed in a state where the tube was stretched flat using a jig. The measurement was performed on 10 points, and the average value was calculated.

-Evaluation of unmodified polymer-like carbon film-
A polymer-like carbon film was formed on the inner surface of a silicone tube having an inner diameter of 4 mm and a length of 400 mm. The composition ratios of carbon atoms, oxygen atoms, and silicon atoms on the surfaces of the undeposited silicone tube and the filmed silicone tube were determined. In addition, the composition ratios of carbon atoms, oxygen atoms, and silicon atoms were also obtained when a silicone tube was placed in a parallel plate type high-frequency plasma generator (manufactured by ADTEC PLASMA TECHNOLOGY) to generate hydrocarbon plasma. ..

The composition ratios of carbon atoms, oxygen atoms and silicon atoms on the inner surface of the undeposited silicone tube (blank) were 53.4 at%, 22.8 at% and 23.8 at%, respectively.

Table 1 shows the composition ratios of carbon atoms, oxygen atoms, and silicon atoms at positions 50 mm, 100 mm, 150 mm, 200 mm, 250 mm, 300 mm, and 350 mm from the tube end on the inner surface of the silicone tube treated by the parallel plate type plasma generator. It came to be shown in.

The average composition ratio on the inner surface of the tube was 53.3 ± 1.2 at% for carbon, 22.8 ± 0.6 at% for oxygen, and 24.0 ± 1.0 at% for silicon. At any position, the ratio of carbon atoms was slightly lower than the value in the blank, and no polymer-like carbon film was formed on the inner surface of the tube. On the other hand, on the outer surface of the tube, carbon was 66.4 at%, oxygen was 18.5 at%, and silicon was 15.1 at%, and the ratio of carbon atoms was higher than that of the blank, and the polymer-like carbon film was formed only on the outer surface of the tube. It was shown to be formed.

Table 1 shows the composition ratios of carbon atoms, oxygen atoms, and silicon atoms at positions 50 mm, 100 mm, 150 mm, 200 mm, 250 mm, and 300 mm from the tube end on the inner surface of the silicone tube (Example) treated by the apparatus shown in FIG. It came to be shown in. In the case of the apparatus shown in FIG. 2, since the discharge electrode 225 was inserted into the silicone tube during film formation, the tube end (0 mm) was set at a position 150 mm away from the position of the tip of the electrode. The average composition ratio on the inner surface of the tube was 72.0 ± 0.8 at% for carbon, 15.9 ± 0.5 at% for oxygen, and 12.1 ± 0.5 at% for silicon. At any position, the ratio of carbon atoms is much higher than the value in the blank, and a polymer-like carbon film is formed on the inner surface of the tube. Further, there is almost no variation in the ratio of carbon atoms, and a uniform polymer-like carbon film is formed on the inner surface of the tube. The oxygen atom and the silicon atom are derived from the silicone tube.

The surface roughness (Ra) determined by the white interferometer was almost the same (average value 0.009 μm) as the untreated case (0.010 μm) when the film was formed by the parallel plate device. When the film was formed by the apparatus shown in FIG. 2, the smoothness was improved (average value 0.005 μm), and the polymer-like carbon film was uniformly formed on the inner surface of the tube.

Table 1 also shows the film thickness of the polymer-like carbon film obtained by the microspectroscopy. As shown in Table 1, the average value of the film thickness was 68.5 ± 6.1 nm, and the coefficient of variation (CV) was 9.1%. In addition, the coefficient of variation at three or more points separated by 50 mm did not exceed 15%. A polymer-like carbon film with a substantially constant film pressure is formed throughout the tube. Also, indentation hardness of the film obtained _{(H IT)} is 0.46 ± 0.05 GPa, it is estimated that Sp2 bonds often polymeric-like carbon film is formed.

-Evaluation of modified polymer-like carbon film-
Table 2 shows the abundance ratio of oxygen atoms obtained from the area intensity of the O1s peak when the unmodified polymer-like carbon film was irradiated with oxygen plasma for 2 seconds by the apparatus shown in FIG. At any position of 50 mm, 100 mm, 150 mm, 200 mm, 250 mm and 300 mm from the tube end, the abundance ratio of oxygen atoms in the modified polymer-like carbon film is higher than that in the case of the unmodified polymer-like carbon film shown in Table 1. It is rising and oxygen atoms are introduced into the polymer-like carbon film.

FIG. 3 shows the C1s peaks of the undeposited blank, the unmodified polymer-like carbon film, and the modified polymer-like carbon film. Compared to the blank and unmodified polymer-like carbon films, the modified polymer-like carbon films have a tail that extends to the high energy side where peaks occur in the presence of CO and O = CO bonds. For this reason, the blank and unmodified polymer-like carbon films contain only a small amount of oxygen atoms bonded to carbon atoms, and the modified polymer-like carbon film contains a high proportion of oxygen atoms bonded to carbon atoms. At least a part of them form a carboxyl group.

Table 2 shows the ratio of oxygen-adjacent carbon to all carbon atoms at each position of 50 mm, 100 mm, 150 mm, 200 mm, 250 mm and 300 mm from the tube end in the modified polymer-like carbon film. The average value of the proportion of oxygen-adjacent carbon at all measurement points was 19.1 at%, and the coefficient of variation was 9.0%. Further, the maximum value of the coefficient of variation at three or more points separated by 50 mm is 12.5%, which does not exceed 18%, and oxygen-adjacent carbon is uniformly introduced into the tube.

The value of the surface roughness (Ra) when the oxygen plasma is irradiated does not change significantly as compared with the case where the oxygen plasma is not irradiated, and the surface roughness due to the oxygen plasma irradiation hardly occurs.

Table 3 shows the relationship between the irradiation time of oxygen plasma and the contact angle. By irradiating the oxygen plasma for 5 seconds, the contact angle with water is significantly reduced as compared with the surface of the undeposited silicone tube and the surface of the polymer-like carbon film not irradiated with the oxygen plasma, and the surface becomes hydrophilic. When the oxygen plasma irradiation time reached 10 seconds, an increase in the contact angle was observed. It is considered that this is because the polymer-like carbon film is damaged by the oxygen plasma and is affected by the underlying silicone tube.

The inner surface coating tube of the present disclosure is useful as a tube through which blood or the like flows because a polymer-like carbon film having a carboxyl group is uniformly formed on the inner surface.

100 Inner surface coating tube 101 Tube body 102 Polymer-like carbon film 200 Formation device 201 Chamber 210 Vacuum exhaust unit 212 Vacuum pump 213 Valve 215 Gas supply unit 216 Cylinder 217 Mass flow controller 218 Flow path switching unit 220 Power supply unit 221 Voltage generator 222 Amplifier 225 discharge electrode

Claims (6)

A flexible tube body with a length of 200 mm or more and
A polymer-like carbon film formed on the entire inner surface of the tube body is provided.
In the polymer-like carbon film, the ratio of oxygen-adjacent carbon to total carbon on the surface is 12 at% or more and 25 at% or less.
The coefficient of variation of the ratio of the oxygen-adjacent carbon to the total carbon at three or more points 50 mm apart from the tube body is 18% or less.
An inner coating tube in which at least a part of the oxygen-adjacent carbon forms a carboxyl group. The inner coating tube according to claim 1, wherein the polymer-like carbon film has a coefficient of variation of 15% or less at three or more points separated by 50 mm from the tube body. The inner surface covering tube according to claim 1 or 2, wherein the inner diameter of the tube body is 0.8 mm or more and 10 mm or less. A non-conductive long thin tube is arranged in a chamber in which the internal pressure can be adjusted, and in a state where a raw material gas containing a hydrocarbon is supplied, plasma is generated inside the long thin tube to generate the long thin tube. A film forming process that forms a polymer-like carbon film on the inner wall surface of the
In a state where a gas containing oxygen atoms is supplied into the long thin tube on which the polymer-like carbon film is formed, plasma is generated inside the long thin tube to generate oxygen atoms on the surface of the polymer-like carbon film. Equipped with an oxygen atom introduction process to be introduced
The long thin tube is arranged in the chamber with a discharge electrode arranged at one end and an open end at the other end.
A method for manufacturing an inner surface covering tube, wherein the plasma is generated by intermittently applying a bias between a discharge electrode and a counter electrode provided apart from the long thin tube. The method for manufacturing an inner surface coating tube according to claim 4, wherein the plasma irradiation time in the oxygen atom introduction step is 1 second or more and 5 seconds or less. In the polymer-like carbon film, the ratio of oxygen-adjacent carbon to total carbon on the surface is 12 at% or more and 25 at% or less.
The coefficient of variation of the ratio of the oxygen-adjacent carbon to the total carbon at three or more points 50 mm apart from the long thin tube is 18% or less.
The method for producing an inner coating tube according to claim 4 or 5, wherein at least a part of the oxygen-adjacent carbon forms a carboxyl group.

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