JP6292610B2 - Tube inner surface hydrophilization method and apparatus - Google Patents

Description

The present invention relates to a surface treatment method for an inner surface of a resin tube using plasma, and a resin tube manufactured by this method.

Resin films and resin tubes for covering metal rods and resin rollers are often required to have properties such as being thermally and chemically stable and excellent in peelability. However, due to its characteristics, the adhesion between the outer surface of the metal rod or resin roller and the coated resin film or resin tube is poor, and the adhesion side surface of the resin film or resin tube is modified to improve adhesion. Consideration has been made to improve performance. For example, it has been proposed that the inner surface of the tube is subjected to etching treatment or primer treatment to improve adhesion (see Patent Document 1). However, the above-described methods generally use chemicals that require attention in handling, and work is troublesome and there is a problem of environmental burden.

On the other hand, in recent years, a technique for generating glow discharge plasma under atmospheric pressure has been used in various applications, and is also used for surface modification treatment of films and sheets. In this technique, a dielectric is inserted between a high-voltage side electrode and a ground-side electrode facing each other at a constant interval, a plasma generating gas is introduced into a discharge portion formed between the electrodes, and a high-voltage AC voltage is applied. Thus, glow discharge plasma is generated under atmospheric pressure, and the presence of the dielectric layer on the electrode suppresses the transition to arc discharge due to excessive current flow. Compared with the conventional plasma treatment under vacuum, the method of surface treatment using this technology, such as surface modification and thin film formation, does not require a vacuum device, so the equipment is compact and inexpensive. Since the in-line continuous processing is easy, the method is being studied.

For example, a mixed gas of a reactive gas and a rare gas is introduced from one end of a tube in which a high voltage electrode and a ground electrode are alternately arranged on the outer periphery, and a high voltage AC voltage is applied between the high voltage electrode and the ground electrode at atmospheric pressure. A method is disclosed in which glow discharge plasma is generated inside a tube to treat the inner surface of the tube or an object inside the tube (see Patent Document 2). However, in such a method, since electrodes are arranged on the outer peripheral surface of the tube, glow discharge plasma is generated not only inside the tube but also between adjacent electrodes on the outer peripheral surface of the tube, and the outer surface is processed by the plasma. Therefore, it cannot be used when it is desired to treat only the inner surface while maintaining the characteristics of the outer surface of the tube. In addition, plasma generated on the outer surface of the tube does not contribute to the treatment of the inner surface of the tube and is lost, and furthermore, the electrode tends to generate heat and become high temperature, and cannot be used for a resin that melts or deforms due to the generated heat. .

As another method, for example, a conductive liquid is used as an external electrode, and a high frequency voltage is applied between the conductive liquid and the internal electrode while introducing a tube in which the inner electrode is disposed. There is a method of generating plasma and treating the inner surface of the tube (see Patent Document 3). However, in these methods, if the pressure in the tube is raised due to the structure of the device, it will flow backward to the extruder that discharges the tube, so the expanded state cannot be maintained only by the tube internal pressure, and the tube diameter is increased. It is necessary to arrange a guide member for maintaining the state, and there is a problem that streaks are generated on the inner surface of the tube by the guide member disposed so as to be in contact with the inner surface of the tube. Even when a roller as described in this specification is coated and adhered, if there are streaks on the inner surface, there is a possibility that adhesion and adhesion may be reduced, which is not preferable. Further, since glow discharge plasma is generated by using the tube to be processed as a dielectric, the conditions under which stable generation of glow discharge plasma can be maintained are very limited when the thickness of the dielectric, that is, the tube to be processed is reduced. For example, the plasma generation conditions are limited by the thickness of the tube to be processed, and the expected effect may not be obtained.

Japanese Patent Laid-Open No. 11-302414 Japanese Patent Laid-Open No. 5-202481 WO2007 / 032425

In order to solve such problems, an object of the present invention is to generate a uniform and stable glow discharge plasma inside the tube when processing the inner surface of the resin tube using atmospheric pressure glow discharge plasma. An object of the present invention is to provide a method for producing a resin tube excellent in adhesiveness by treating only the inner surface of the tube while maintaining the characteristics of the outer surface of the tube, and a resin tube produced by this method.

In order to solve the above-mentioned problems, the present inventors have intensively studied. As a result, the high-voltage electrode and the ground electrode are not disposed inside and outside the tube as in the prior art, but both electrodes are disposed inside the tube. It has been found that a uniform and stable plasma generation region can be secured inside the tube by arranging.

That is, in order to achieve the above object, in the present invention, a cylindrical shape in which a pattern design is formed on the outer surface of the resin tube continuously discharged from the extrusion molding apparatus and the inner surface is covered with the conductor. In order to discharge gas from the gap between the resin tube and the discharge electrode, and a gas introduction mechanism for introducing gas into the gap between the resin tube and the discharge electrode The resin tube and the discharge electrode by applying a voltage from a high frequency power source to the discharge electrode while introducing the gas from the gas introduction mechanism and discharging the gas from the gas discharge mechanism During this, atmospheric pressure glow discharge plasma is generated to treat the inner surface of the resin tube.

In the production method of the present invention, in the step of continuously discharging the resin tube from the conventionally known extrusion molding apparatus, the inner diameter regulating member is disposed after being discharged from the die at the tip of the extrusion molding apparatus, and on the downstream side thereof. Discharge electrodes are arranged. The discharge electrode is composed of a cylindrical dielectric and a conductor member, and has a structure in which a pattern design is formed of a conductor component on the outer surface of the dielectric and the inner surface is covered with a conductor. With the pattern of the conductor member on the outer surface of the dielectric, it is possible to make the plasma generation density uniform on the entire discharge electrode surface, and it is possible to reduce the loss current other than that used for generating the plasma gas. The pattern design is not limited, but it is necessary to make the pattern in consideration of the generation efficiency and generation density of plasma gas. The electrode is disposed only inside the tube and does not have any influence on the outer surface of the tube due to the generated plasma.

In the method for producing a resin tube according to the present invention, the gap between the inner surface of the resin tube and the outer surface of the discharge electrode is preferably arranged to be 0.1 mm or more and 8 mm or less, more preferably 0. 1 mm or more and 5 mm or less. This is because if the gap is large, the plasma gas concentration is lowered and the treatment effect is not fully exhibited, and if the high voltage is not applied, the progress of the treatment is delayed, but the electrode temperature rises by applying a high voltage, This is to avoid the phenomenon that the temperature of the resin tube rises and deforms, and in the extreme case, the tube melts. Of course, if the conditions are adjusted and a higher voltage is applied, the gap can be widened, but there are practical problems such as risk of work, increase in the amount of heat generated, and the power supply being expensive.

Further, in the present invention, a voltage is applied to the discharge electrode while introducing a gas into the gap between the resin tube and the discharge electrode, and the inner surface of the resin tube is caused to flow by the plasma gas generated between the inside of the resin tube and the discharge electrode. Surface treatment. A high-frequency power source to be used is suitable for a frequency range of 5 to 50 kHz, a discharge voltage of 5 to 15 kV rms, and a pulse modulation frequency of 0 to 5 Hz. Conditions such as a frequency and a voltage are the processing speed and the type of gas to be introduced. And the concentration, the material of the electrode, the material of the resin tube to be treated, etc.

In the present invention, the resin tube is preferably a fluororesin tube.

According to this configuration, when processing the inner surface of the resin tube using the atmospheric pressure glow discharge plasma, a uniform and stable glow discharge plasma can be generated inside the tube regardless of the diameter and thickness of the tube. In addition, it is possible to treat only the inner surface of the tube without affecting the outer surface of the tube at the same time, and at the same time, it has better adhesion by not scratching the inner surface of the tube. A resin tube can be provided.

It is a figure explaining the melt-extrusion molding apparatus provided with the surface treatment function of the tube inner surface. It is a figure explaining the metal mold | die (die | dye) attached to the front-end | tip of an extruder, and an internal diameter control member. It is an arrangement plan of electrodes arranged inside a resin tube. It is a schematic diagram which shows an example of the structure of an electrode. (B) is a side view. (A) is sectional drawing in the AA 'line of (b). (A), (b) and (c) is a schematic side view which shows the example of other embodiment of an outer surface side electrode pattern. It is a schematic diagram of the discharge mechanism of an electrode.

The embodiments described below do not limit the invention according to the claims, and all combinations of features described in the embodiments are not necessarily essential for the establishment of the present invention.

FIG. 1 is a cross-sectional view showing an embodiment of a melt extrusion molding apparatus having a surface treatment function on the inner surface of a tube. The melt extrusion molding apparatus shown in FIG. 1 includes an extruder 1 that adjusts a resin material introduced from a hopper 12 to a molten state and extrudes resin by rotation of a screw 11, and a die (die) attached to the tip of the extruder. ) 2, the inner diameter regulating member 3 that cools by contacting the inner peripheral surface of the resin tube A discharged from the die 2 to the outside, and the resin tube cooled and solidified by the inner diameter regulating member 3 is fixed through a tension roll. It is based on a conventionally known tube manufacturing apparatus composed of a take-up machine 5 that takes up at a speed and a winder 6 that continuously takes up a resin tube taken up by the take-up machine 5. A configuration necessary for the surface treatment is provided. In the present invention, for the surface treatment of the inner surface of the resin tube, the discharge electrode 4 is disposed inside the resin tube A discharged from the die 2 and gas is introduced into the gap between the resin tube A and the discharge electrode 4. And a gas discharge mechanism for keeping the pressure in the gap between the resin tube A and the discharge electrode 4 constant.

FIG. 2 is a cross-sectional view showing an embodiment of the die 2 and the inner diameter regulating member 3 attached to the tip of the extruder 1. The arrows in the figure indicate the resin flow and the tube discharge direction. As shown in FIG. 2, the main body 21 of the die 2 has a flow path 22 through which a molten resin extruded from an extruder (not shown) passes, and an annular shape for forming the molten resin into a tube shape. The outlet hole 23 is formed. Further, the inner diameter regulating member 3 is provided so as to pass through the center portion of the outlet hole 23 formed in an annular shape in the main body 21 and protrude from the die 2. The inner diameter regulating member 3 shown in FIG. 2 has a cylindrical shape, but has a cross-sectional shape of a portion that contacts the inner surface of the tube, such as a cone or a conical shape in which the upper and lower surfaces (the bottom surface and the surface facing the bottom surface) of the cone are flat. It may be a circular shape. The outer diameter of the inner diameter regulating member 3 is determined according to the inner diameter of the resin tube to be manufactured. The molten resin discharged from the extruder on the left side of the drawing is discharged from the outlet hole 23 of the die 2 and is taken up at a constant speed while coming into contact with the outer peripheral surface of the inner diameter regulating member 3 and cooled and solidified. Here, the material of the resin tube A is not particularly limited as long as it can be extruded, but a fluororesin is particularly suitable. Examples of the fluororesin include polytetrafluoroethylene resin (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA), fluorinated ethylene-propylene copolymer resin (FEP), and ethylene-tetrafluoroethylene. Examples thereof include a copolymer resin (ETFE) and a polyvinyl fluoride resin. Among these, PFA is particularly preferable.

FIG. 3 is a side view showing an example of the arrangement of the discharge electrodes arranged inside the resin tube. As shown in FIG. 3, the discharge electrode 4 is disposed at the tip of the inner diameter regulating member 3. The gap between the resin tube A and the discharge electrode 4 is desirably as small as possible so that the resin tube A does not touch the discharge electrode 4, and is preferably 0.1 mm or more and 8 mm or less. More preferably, it is 0.1 mm or more and 5 mm or less. By reducing the gap between the resin tube A and the discharge electrode 4, the consumption gas can be reduced, and by increasing the plasma gas concentration in the space formed between the inner surface of the resin tube A and the discharge electrode 4, Surface treatment can be performed more effectively. Inside the inner diameter regulating member 3, a cooling medium channel 31 for flowing a medium for cooling the inner diameter regulating member 3 and the discharge electrode 4, a gas is introduced into the resin tube A, and a gas is discharged from the resin tube A The metal electric wire 44 connected to the high-frequency power source 45 connected to the gas introduction / discharge passage 32 and the discharge electrode 4 is arranged inside.

FIG. 4 is a schematic diagram showing an example of the structure of the discharge electrode. (B) is a side view, (a) is sectional drawing in the AA 'line of (b). As described above, the structure of the discharge electrode is such that the conductor member 43 is disposed on the inner surface of the cylindrical dielectric 41 and the conductor member 42 having a pattern symbol made of a conductor component is disposed on the outer surface. Although FIG. 4 shows an electrode having a mesh pattern, the present invention is not limited to this, and various other forms such as a rod shape, a mesh shape, and a spiral shape are possible. FIGS. 5A, 5B and 5C are schematic side views showing other embodiments as electrode patterns. Further, as the cylindrical dielectric, not only a cylinder but also a cylindrical shape matching the shape of the processed object such as an ellipse, a triangle, or a quadrangle can be selected. As the dielectric material, a material excellent in heat resistance and dielectric properties such as ceramics such as alumina Al ₂ O ₃ and glass is suitable. As a material of the conductor member, various conductive materials such as copper, silver, nickel, aluminum, and carbon can be selected. As shown in FIG. 3, the discharge electrode 4 is connected to a high-frequency power source 45 by an electric wire 44 through the inside of the inner diameter regulating member 3 and the inside of the mold 2. A voltage is applied to the conductor member 42 on the outer surface of the cylindrical dielectric 41, and grounding is performed on the conductor member 43 side on the inner surface. The voltage is obtained by sandwiching the dielectric between the conductor members 42 and 43 on both surfaces. It is a structure to apply. Due to the electrode structure in which the inside and outside of the cylindrical dielectric are sandwiched between conductors, the thickness of the dielectric can be adjusted as desired, unlike the conventional method in which the resin tube to be surface-treated is used as the dielectric and the electrode is also placed outside the tube. It is possible to expand the adjustment range of the conditions of the glow discharge plasma. The voltage applied between the electrodes is not a problem if the temperature is such that the resin tube is not affected by deformation or the like, but it is desirable that the voltage be 50 kHz or less if possible. Depending on the type of gas introduced into the resin tube, if the frequency is too high, the dielectric may be damaged. When the voltage is too high, the electrode generates heat and becomes high temperature, and loss due to heat generation increases. In addition, there is a case where a transition from glow discharge to arc discharge is not desirable. If it shifts to arc discharge, problems, such as melting a tube, will arise. As a high-frequency power source to be used, a low-cost power source having a frequency of 50 kHz or less that has high generation efficiency of plasma gas and does not require a matching circuit is sufficient because the discharge electrode is configured with a pattern design.

In the present invention, a gas (excited gas) that is easily plasmified or a mixed gas of an excited gas and a reactive gas is supplied from the gas introduction / discharge path 32 to the gap between the resin tube A and the discharge electrode 4. A plasma gas is generated by applying a voltage from the high-frequency power source 45 to the substrate. FIG. 6 is a schematic diagram showing the state of discharge in the vicinity of the electrode at this time. A voltage is applied from the electrode 46 to the metal member 42, and an electric field is generated between the electrode 46 and the metal member 43. This electric field polarizes the dielectric 41, the electric field concentrates on the surface of the dielectric 41 where the metal member 42 is not present and the end of the metal member 42, the electrons are accelerated, and partial discharge occurs. This partial discharge grows in the direction of the arrow along the surface of the dielectric 41. Excited gas molecules and reactive gas molecules in the glow discharge region 47 near the dielectric surface collide with high-speed electrons and become plasma. This plasma comes into contact with the inner surface of the resin tube A and cuts the CC bond or CF bond on the inner surface of the resin tube A. At the same time, the plasma gas component, the moisture present in the resin tube A, or A component of the reaction gas is introduced as a functional group on the inner surface of the resin tube A. The gas introduced into the resin tube A is at least one gas selected from a rare gas and nitrogen as an excitation gas. Although only the excitation gas may be used, it is preferable to use a reactive gas in combination with a treatment of a resin having low hydrophilicity such as a fluororesin. The reactive gas is not limited as long as it is a low molecular gas that can be decomposed by plasma, but its component may be selected depending on the use of the tube. Specific examples of the reactive gas used in combination with the excitation gas include hydrogen gas, silicon-based gas, carbon monoxide, methane gas, propane gas, butane gas, acrylic acid ester, acrylic acid, methacrylic acid, vinyl acetate, acetone, and hydroxyethyl methacrylate. Examples include those obtained by gasifying glycidyl methacrylate, propargyl alcohol, water, and the like, but are not limited thereto. These gases are decomposed by collisions with electrons in the plasma, ultraviolet rays, and reaction with plasma generated particles, and become radical states such as · SI, · OH, · C = O, · COOH, and C -C bond, CF bond is introduced as a functional group on the cut inner surface of the tube.

A plurality of gas introduction / exhaust passages 32 for introducing gas into the resin tube A are arranged so that there is no non-uniform gas concentration. The shape of the gas introduction / discharge path 32 may be arbitrary as long as it can be uniformly introduced into the resin tube A. Each gas introduction rate may be increased or decreased according to the processing rate, but the excitation gas is in the range of 0.2 to 3 L / min at room temperature and atmospheric pressure, and the reactive gas is also 0.01 L / min. The flow rate may be adjusted according to the desired degree of processing. As the reactive gas, a gaseous gas is introduced as it is at room temperature, but a solid or liquid gas is introduced after being vaporized by a vaporizer. When a mixed gas of excitation gas and reaction gas is used, it may be introduced into the resin tube A in a mixed state or separately.

As shown in FIG. 1, the resin tube A discharged by the extruder 1 and subjected to the surface treatment on the inner surface is taken up by the take-up machine 5. The take-up machine 5 includes a pair of rotating bodies each composed of a pair of rolls arranged at a predetermined interval and a single endless belt wound around the pair of rolls. Two sets are arranged so as to contact the surface. The resin tube A is sandwiched between the endless belt portions of the two sets of rotating bodies of the take-up machine 5 and taken up at a constant speed. The take-up speed may be adjusted according to the excitation conditions, the degree of desired processing, and the like. In the present invention, since it is not desired to make a crease in the tube, the steps from discharging the tube to taking it out are arranged in the horizontal direction.

Hereinafter, the present invention will be described in more detail with reference to an example in which the melt extrusion molding apparatus shown in FIG. 1 is used.

Example 1 A melt extrusion molding apparatus schematically shown in FIG. 1 was produced. A die having a diameter of 25 mm was attached to a basic extrusion molding apparatus, and an inner diameter regulating member was disposed so as to penetrate the center of the die and protrude from the tip of the die. In this example, the inner diameter regulating member having an outer diameter of 24.5 mm in contact with the tube was used. A discharge electrode was attached to the tip of the inner diameter regulating member. A cooling medium flow path for cooling the inner diameter restriction member is provided inside the inner diameter restriction member, and a flow path for feeding the cooling medium to the inside of the discharge electrode through an adapter to which the discharge electrode is attached. Further, inside the inner diameter regulating member, six introduction / discharge paths for introducing gas into the gap between the resin tube and the discharge electrode and discharging gas from the gap were provided. As shown in FIG. 4, the discharge electrode is formed by bonding an aluminum sheet having a thickness of 80 μm to the inner surface of a cylindrical alumina ceramic tube having an outer diameter of 22 mm and an inner diameter of 20 mm, and forming a comb-shaped aluminum 80 μm thickness on the outer surface of the tube. The sheet was made by bonding. As the comb shape, a tooth having a tooth interval of 6 mm and a tooth thickness of 3 mm was used. A high-frequency power source having a maximum capacity of 50 kHz was used, and a connection was made such that a voltage was applied to the conductor member on the outer surface side of the discharge electrode and the conductor member on the inner surface side was grounded. In this example, the electrode outer diameter was set so that the distance between the outer surface of the discharge electrode and the inner surface of the resin tube was 1 mm, and the length of the electrode was 15 cm. In this way, a surface treatment resin tube forming apparatus was prepared.

The resin tube was molded using the above molding apparatus. The raw material resin was a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA: 451HP-J) manufactured by Daikin Industries, Ltd., and the extrusion temperature was set to 390 ° C. A take-up speed of the take-up machine was 2 m / min, and a tube having a tube outer diameter of 24.5 mm and a wall thickness of 30 μm was formed. In this example, nitrogen gas was used as the excitation gas and water vapor was used as the reactive gas. The flow rate of nitrogen gas was 1 L / min, the concentration of water vapor was 25000 ppm, and the gas was introduced from the gas introduction / discharge passage into the space between the outer surface of the discharge electrode and the inner surface of the resin tube in a state where the excitation gas and the reaction gas were mixed. . The pressure inside the tube was adjusted by discharging the gas. A voltage was applied to the high frequency side electrode on the outer surface of the discharge electrode under the conditions of a frequency of 5 to 10 kHz, a discharge voltage of 10 kV, and no pulse modulation to generate plasma. A PFA tube in which only the inner surface was treated with the generated plasma was obtained.

[Comparative Example 1] Using a melt extrusion molding apparatus in which a high-pressure electrode is disposed inside the tube and a ground electrode is disposed outside the tube as in Prior Art Document 3, a tube is extruded in the same manner as in Example 1, and a surface treatment apparatus using plasma is provided. Although the treatment was performed by passing it, the voltage could not be raised to a predetermined voltage while maintaining a stable glow discharge, and sufficient treatment could not be performed.

[Evaluation of surface treated product] [1. Hydrophilicity] Hydrophilicity evaluation by surface treatment was performed by contact angle measurement. Although the contact angle of the tube inner surface before the surface treatment was 135 °, the contact angle of the tube inner surface of Example 1 was 83 °, and the effect of the hydrophilic treatment was confirmed. The tube color was transparent, and no browning was observed when chemical treatment was applied. Moreover, there was no change in the contact angle of the tube outer surface. [2. Adhesiveness] The adhesiveness between the inner surface of the tube of Example 1 and silicon rubber was evaluated. The tube of Example 1 was cut open, and the inner surface thereof and the primary vulcanized silicon rubber were pressure-bonded to confirm the peel strength. The pressure bonding conditions were a pressure of 1 kg, a temperature of 200 ° C., and a pressure bonding time of 4 hours. The peel strength was measured based on the measurement method defined in JIS Z0237. The tube before the surface treatment did not adhere at all, but the tube of Example 1 developed an adhesive strength of 40 N / cm. The peel strength of the tube / silicon rubber adhesive sheet was exposed at 200 ° C. for 100 hours, and the peel strength was measured. As a result, it was confirmed that the adhesive strength of 38 N / cm was maintained and the heat resistance was good. It was done.

The tube produced using the method of the present invention in Example 1 exhibits hydrophilicity equivalent to chemical treatment that could not be achieved by a conventionally known continuous treatment method, and also has chemical properties for adhesion to other materials. Adhesiveness equal to or better than chemical treatment, which could be achieved without using a primer or the like. In addition, compared with a conventionally known plasma processing technique, the energy input to generate the excitation gas is suppressed to a low level, and stable and uniform plasma can be generated. Therefore, a sufficient effect was demonstrated by short-time plasma irradiation while continuously forming the tube. In addition, since the plasma gas is uniform and can be turned into plasma with low energy, even if the tube thickness is very thin, it is possible to perform surface treatment on the inner surface without causing pinholes or tearing in the tube. It was. Further, since no electrode is disposed outside the tube and plasma is generated by the electrode inside the tube, the outer surface of the tube was not affected at all.

As described above, according to the present invention, when the inner surface of the resin tube is processed using the atmospheric pressure glow discharge plasma, the glow discharge is uniform and stable inside the tube regardless of the diameter and thickness of the tube. Plasma can be generated. In addition, it is possible to treat only the inner surface of the tube without treating the outer surface of the resin tube at the same time, and at the same time, adhesion without creases or scratches on the outer surface of the tube without scratching the inner surface of the tube A resin tube excellent in properties can be provided. The tube treated by the method of the present invention is useful for each application that requires adhesion to other materials.

DESCRIPTION OF SYMBOLS 1 Extruder, 11 Screw, 12 Hopper, 2 Mold (die), 21 Mold body, 22 Resin flow path, 23 Outlet hole, 3 Inner diameter control member, 31 Cooling medium flow path, 32 Gas introduction / discharge path, 4 Discharge electrode, 41 dielectric, 42 conductor member (outer surface), 43 conductor member (inner surface), 44 electric wire, 45 high-frequency power supply, 46 electrode,
47 Glow discharge area 5 Take-up machine, 6 Winding machine, A Resin tube

Claims (3)

Disposed inside the resin tube continuously discharged from the extrusion molding apparatus is a discharge electrode made of a cylindrical dielectric material whose outer surface is composed of a pattern design with a conductor component and whose inner surface is covered with a conductor. A gas introduction mechanism for introducing gas into the gap between the resin tube and the discharge electrode; and a gas discharge mechanism for discharging gas from the gap between the resin tube and the discharge electrode. While introducing gas from and discharging gas from the gas discharge mechanism, by applying a voltage from a high frequency power source to the discharge electrode, an atmospheric pressure glow discharge plasma is generated between the resin tube and the discharge electrode, A method of manufacturing a resin tube, comprising: treating the inner surface of the resin tube with an atmospheric pressure glow discharge plasma in contact with the inner surface of the resin tube. The method for producing a resin tube according to claim 1, wherein the gap between the inner surface of the resin tube and the outer surface of the discharge electrode is 0.1 mm or more and 8 mm or less. The method of manufacturing a resin tube according to claim 1 or 2, wherein the resin tube is made of a fluororesin.

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