JP4812404B2 - Plasma surface treatment apparatus and surface treatment cylindrical substrate manufacturing method - Google Patents

Description

  The present invention relates to a plasma surface treatment apparatus for a cylindrical substrate and a method for manufacturing a surface-treated tubular substrate using the treatment apparatus.

Many methods for surface treatment of a substrate with plasma are known.
For example, an apparatus that treats the inner surface of a plastic tube with atmospheric pressure glow discharge plasma in which the ground side electrode and the high voltage side electrode are arranged coaxially with each other and facing each other via a plastic tube is disclosed (patent) Reference 1). However, this apparatus has a problem that a uniform discharge plasma cannot be formed and the uniformity of the surface treatment is poor.

  Also disclosed is a coaxial atmospheric pressure glow discharge generator for treating the inner surface of a plastic tube in which a spacer is secured in a state in which a gas flow can be secured on the outer periphery of the inner (treated surface side) electrode. (Patent Document 2). However, this technology is intended to prevent the plastic tube from shaking and to secure the plasma generation region and gas flow by providing a spacer that separates the plastic tube and the plastic tube stabilizing member. Not trying. In this device, since the spacer is made of a non-conductive material (preferably a fluororesin), processing such as adhesion processing for attaching a different material (spacer) to the electrode (metal) surface is necessary and not simple. Especially when the tube has a small diameter, it is difficult to process the electrode. Furthermore, although the gas flow is good, there is a problem that the homogeneity of the plasma electric field is inferior and as a result, the homogeneity of the processing is also insufficient.

On the other hand, it is known that a glow discharge is uniformly stabilized by providing a groove on the electrode, and an atmospheric pressure plasma reactor having a groove on the back surface of the processing side electrode is disclosed (Patent Document 3). This apparatus treats a plate-like substrate and cannot improve the uniformity of the surface treatment of the cylindrical substrate.
Japanese Patent Laid-Open No. 2002-60521 JP 2002-86580 A Japanese Patent Laid-Open No. 2-15171

  In the plasma surface treatment of a cylindrical substrate, the present invention simply provides an apparatus that enables plasma treatment with higher homogeneity, and a uniformly treated surface-treated cylinder using the treatment apparatus. It is providing the manufacturing method of a base material.

As a result of intensive studies to solve the above problems, the present inventor has found that the above problems can be solved by using an electrode provided with a groove having a specific structure, and has completed the present invention.
That is, the present invention relates to a coaxial plasma having an outer electrode of a cylindrical base material arranged coaxially and an inner electrode arranged to face the outer electrode through the cylindrical base material. In the surface treatment apparatus, both the electrodes are made of a conductive material , and a groove through which gas can flow in the axial direction is formed on the surface of the electrode on the plasma surface treatment side of these electrodes. A cylindrical substrate plasma surface treatment apparatus characterized in that the surface of the electrode made of a conductive material has an uneven surface . The present invention also provides a method for producing a surface-treated cylindrical substrate, wherein the surface treatment is performed using the plasma surface treatment apparatus.

In the plasma surface treatment of a cylindrical substrate, the present invention makes it possible to provide an apparatus having a more uniform surface treatment than in the past with a simpler structure, and further obtained by surface treatment with the apparatus. Since the cylindrical base material has a more homogeneous treatment surface, it is extremely valuable industrially.
Moreover, since the structure of the electrode is particularly simple, it can be easily applied to a cylindrical base material having a small inner diameter.

Hereinafter, embodiments of the present invention will be described.
[Plasma surface treatment equipment-inner surface discharge type]
FIG. 1 is a schematic cross-sectional view of a plasma surface treatment apparatus according to an embodiment of the present invention. The plasma surface treatment apparatus according to this embodiment is for treating the inner surface (inner peripheral surface) of a cylindrical base material as a cylindrical base material.

  As shown in FIG. 1, the plasma surface treatment apparatus according to the present embodiment includes an outer electrode 1 disposed outside a cylindrical base material 3 as a processing target, and an inner surface disposed inside the cylindrical base material 3. The electrode 2 and the fixtures 71 and 72 which fix the outer electrode 1, the inner electrode 2, and the cylindrical base material 3 are provided.

  The outer electrode 1 has a cylindrical shape. In the present embodiment, the cross-sectional shape of the outer electrode is a circle coaxial with the hole. However, as is apparent from the spirit of the invention, it may be determined according to the substrate to be treated, and is not particularly limited. The inner diameter of the outer electrode 1 is 0 to 0. 0 than the outer diameter of the cylindrical base material 3 so that the cylindrical base material 3 arranged on the inner coaxial side of the outer electrode 1 fits inside the outer electrode 1. It is preferably about 2 mm larger.

  The thickness of the outer electrode 1 is not particularly limited, but is usually 0.5 mm or more from the viewpoint of maintaining the shape.

  The material of the outer electrode 1 may be any material as long as it has conductivity. Specifically, the material is selected from simple metals such as copper and aluminum, alloys such as stainless steel and brass, and intermetallic compounds.

  As shown in FIG. 1, the outer electrode 1 is electrically connected to a power source 5 via a matching unit 4 as desired.

  Although the inner electrode 2 has a substantially cylindrical shape as a whole in this embodiment, it may be determined according to the base material to be treated in the same manner as the outer electrode, and the shape is not limited. A spiral groove 2 a is formed in a portion facing the cylindrical base material 3 arranged on the outer coaxial side of the inner electrode 2. The spiral groove 2a is a groove through which gas can flow in the axial direction. In this embodiment, the spiral groove 2a is continuous in a certain direction from one end of the electrode to the other end along the axis (the gas flow is stagnated). Not), especially a periodic spiral structure. Here, the end of the electrode means an effective end of the electrode, and does not mean a physical end as a metal electrode. Also, the constant direction from one end of the electrode to the other end along the axis means that the direction of the groove is always from one end to the other end and not in the opposite direction. It does not necessarily mean that the inclination with respect to the axis is constant.

  The distance between the grooves (distance between the center of the groove and the center of the groove; hereinafter may be represented by “p”) is preferably 0.1 to 3.0 mm, more preferably from the viewpoint of the homogeneity of the surface treatment. Is 0.1 to 2.0 mm, particularly preferably 0.1 to 1.5 mm.

  The cross-sectional shape of the groove is V-shaped in FIG. 1, but is not limited to this, and may be, for example, a trapezoidal shape, a rectangular shape, a semicircular shape, or the like. From the point of homogeneity of the surface treatment, the groove depth is preferably 0.1 × p to 1.0 × p (mm), and the groove width is 0.5 × p to 1.0 ×. It is preferable that it is p (mm). Here, the width of the groove refers to the width of the uppermost portion of the groove.

  In the present embodiment, the groove formed in the inner electrode 2 has a spiral shape, but is not limited to this, and may be any groove that allows gas to flow in the axial direction. For example, it may be linear as shown in FIGS. In the example shown in FIG. 4 and FIG. 6, a plurality of linear grooves are formed in parallel to the axis in the portion of the inner electrode 2 that faces the cylindrical substrate 3. The interval between the grooves, the cross-sectional shape, the depth of the groove, and the width of the groove are the same as in the case of the spiral groove.

  The outer diameter of the inner electrode 2 is 0 to 0.2 mm from the inner diameter of the cylindrical base material 3 so that the cylindrical base material 3 arranged coaxially with the inner electrode 2 fits outside the inner electrode 2. It is preferable that the degree is small.

  The material of the inner electrode 2 may be any material as long as it has conductivity. Specifically, the material is selected from simple metals such as copper and aluminum, alloys such as stainless steel and brass, and intermetallic compounds.

  The inner electrode 2 is electrically grounded as shown in FIG. The electrode on the grounding side may be the outer electrode 1. In this case, the inner electrode 2 is electrically connected to the power source 5 through the matching unit 4 as desired.

  The fixtures 71 and 72 are not particularly limited as long as they have electrical insulation and can support and fix the outer electrode 1, the inner electrode 2, and the cylindrical substrate 3 so that a desired surface treatment can be performed. Moreover, if it can fix, only one side is good. In the present embodiment, the fixtures 71 and 72 are formed with a cylindrical hollow portion, and the inner electrode 2 penetrates the hollow portion of one fixture 71 and does not reach the other fixture 72. It is provided as follows. The gas for performing the plasma surface treatment is not particularly limited to the introduction method as long as it flows between the electrode on the surface treatment side and the surface treatment side of the substrate from one end of the electrode to the other end. . For example, it is introduced from between one of the fixtures 71 and 72 and the inner electrode 2 and is discharged from the hollow portion of the other fixture through the spiral groove of the inner electrode 2 (in FIG. 1, it is fixed). It is introduced from the tool 71 side). The gas is supplied from a gas pipe 10 provided with a valve 11, for example, as shown in FIG.

  The size of the cylindrical substrate 3 to be subjected to the surface treatment is not particularly limited, but the present invention is a small diameter cylinder having an inner diameter of 1 to 10 mm and a thickness of 0.1 to 5 mm. This is particularly effective when the surface treatment of the mold substrate is performed.

  Examples of the material of the cylindrical base material 3 (cylindrical base material) include plastic (resin) having electrical insulating properties, glass, ceramics, and the like. The type of plastic is not particularly limited and may be any molding material, particularly any electrically insulating material that can be molded into a cylindrical shape, for example, a polyolefin such as polyethylene or polypropylene, or a polyester such as polyethylene terephthalate. , Polyurethane, polybutadiene, polyvinyl chloride, silicone resin, polytetrafluoroethylene, polystyrene and the like.

[Plasma surface treatment equipment-External discharge type]
FIG. 2 is a schematic cross-sectional view of a plasma surface treatment apparatus according to another embodiment of the present invention. The plasma surface treatment apparatus according to this embodiment is for treating the outer surface (outer peripheral surface) of a cylindrical base material.

  As shown in FIG. 2, the plasma surface treatment apparatus according to this embodiment includes an outer electrode 1 disposed on the outer side of a cylindrical substrate 3 as a processing target and an inner electrode disposed on the inner side of the cylindrical substrate 3. The electrode 2 and the fixtures 71 and 72 which fix the outer electrode 1, the inner electrode 2, and the cylindrical base material 3 are provided.

  The outer electrode 1 has a cylindrical shape. The cross-sectional shape of the outer electrode is circular in the present embodiment, but is not particularly limited as in the case of the inner surface discharge type. A spiral groove 1a is formed on the peripheral wall. The configuration of the spiral groove 1a is the same as the configuration of the spiral groove 2a formed in the inner surface discharge type inner electrode 2. Further, instead of the spiral groove, a linear groove as described above may be formed. The inner diameter, thickness, material and the like of the outer electrode 1 are the same as those of the inner surface discharge type outer electrode 1.

  The inner electrode 2 basically has the same configuration as that of the inner surface discharge type inner electrode 2 except that no groove is formed. In FIG. 2, one end of the inner electrode 2 has a reduced diameter, but is not limited thereto. The outer diameter of the inner electrode 2 (part fitted with the cylindrical substrate 3), material, and the like are the same as those of the inner surface discharge type inner electrode 2.

  The fixtures 71 and 72 are not particularly limited as long as they have electrical insulation and can support and fix the outer electrode 1, the inner electrode 2, and the cylindrical substrate 3 so that a desired surface treatment can be performed. Moreover, if it can fix, only one side is good. In the present embodiment, the fixtures 71 and 72 are provided with gaps, and the gas for performing the plasma surface treatment is performed between the electrode on the surface treatment side and the surface treatment side of the base material. The introduction method is not particularly limited as long as it flows from one end to the other end. For example, it is introduced from between one of the fixtures 71 and 72 and the inner electrode 2 and is discharged from the hollow portion of the other fixture through the spiral groove of the inner electrode 2 (in FIG. 1, it is fixed). It is introduced from the tool 71 side). The gas is supplied from a gas pipe 10 provided with a valve 11, for example, as shown in FIG.

  The size and material of the cylindrical base material 3 to be surface-treated are the same as the size and material of the inner surface discharge type cylindrical base material 3.

  According to the plasma surface treatment apparatus (inner surface discharge type / outer surface discharge type), surface treatment with excellent homogeneity can be performed. In particular, the plasma surface treatment apparatus can be configured with a simple structure without the need for a member such as a spacer, and since the electrode structure is simple, it can be applied to a cylindrical substrate having a small inner diameter. It has the advantage of being easy.

[Method for producing surface-treated cylindrical substrate]
In order to produce a surface-treated cylindrical substrate using the plasma surface treatment apparatus (internal discharge type / external discharge type), plasma surface treatment may be performed on the cylindrical substrate 3 as follows. . The cylindrical substrate 3 is set in a plasma surface treatment apparatus by fixtures 71 and 72 as shown in FIG. 1 or FIG.

  The pressure at the time of plasma surface treatment is preferably in the vicinity of atmospheric pressure that does not require a vacuum pump or the like in consideration of apparatus cost and processing cost. Specifically, it is 0.01 to 0.12 MPa.

  As the power source 5, for example, an AC power source device can be used. The power source 5 may be a single frequency or a unit that generates a periodic pulse voltage. A normal apparatus used when plasma-treating the material can be used and there is no particular limitation.

  When a power supply device having a high frequency, for example, a high frequency power supply device of 0.1 MHz or more is used, the plasma density can be increased as the frequency increases. However, since the temperature rise of the cylindrical base material and / or the electrode becomes a problem as the frequency becomes higher, it is desirable to use a high frequency power supply device having a function of time-modulating the high frequency power.

  The periodic pulse voltage applied between the outer electrode 1 and the inner electrode 2 is appropriately adjusted so as to have an electric field strength necessary for generating plasma between the electrodes. Considering prevention of occurrence of arc discharge and stable formation of discharge plasma, the electric field strength is preferably in the range of 1 to 100 kV / cm.

  The pulse rise time is preferably as fast as possible, specifically 100 μs or less. By increasing the rise time, ionization of the gas existing between the electrodes can be performed efficiently. On the other hand, the fall time of the pulse is preferably as fast as possible, similarly to the rise time, and is preferably 100 μs or less.

  The pulse width (pulse duration) is preferably in the range of 0.1 to 1000 μs in consideration of stable formation of discharge plasma and prevention of arc discharge. The pulse repetition frequency is preferably selected in the range of 0.1 to 100 kHz in consideration of surface treatment time and prevention of arc discharge. The pulse waveform may be a triangular wave or a sawtooth wave excluding a sine wave in addition to an impulse and a square wave, and is not particularly limited as long as the above conditions are satisfied.

  Examples of the gas introduction means include a piping member such as a valve, a tube, and a joint, a mass flow controller, and a vaporizer.

  As the gas, there are a case where an inert gas essential for forming discharge plasma is used alone, and a case where a mixed gas obtained by adding a small amount of reactive gas to the inert gas as required is used. Here, the inert gas refers to one or more kinds of single or mixed gas selected from rare gases such as helium and argon and nitrogen gas. Further, an inert gas such as nitrogen gas may be used as the reactive gas.

  When a small amount of the reactive gas is added to the inert gas, a known gas can be used as the reactive gas to be mixed with the inert gas as described above when the substrate is subjected to plasma treatment. For example, methane, tetrafluoromethane, ethylene, propylene, tetrafluoroethylene, hexafluoropropylene, carbon dioxide, oxygen, nitrous oxide, nitrogen trifluoride, silane, disilane, trimethylsilane, tetramethylsilane, ammonia, etc. It is done. The addition amount may be within a well-known preferable range, and is usually preferably 0.001 to 5.0% by volume with respect to the inert gas.

  In the plasma surface treatment apparatus, since the treatment surface of the cylindrical substrate 3 and the inner electrode 2 or the outer electrode 1 in which the groove is formed are disposed in proximity to each other, the plasma surface treatment is performed as described above. When this is done, most of the gas flows through the grooves formed in the inner electrode 2 or the outer electrode 1, and the space in which the discharge plasma is formed is considered to be mainly in the grooves of the inner electrode 2 or the outer electrode 1. . Since the discharge plasma can be confined in a very narrow space due to the gas flow groove formed in the electrode, higher-energy active species are excited in the discharge space. Thereby, a high-density stable discharge plasma can be formed in the very vicinity of the treatment surface of the cylindrical substrate 3 so as to cover the entire treatment surface, and a surface treatment excellent in homogeneity can be performed. It seems to be possible.

  According to the plasma surface treatment apparatus or the method for producing a surface-treated cylindrical base material described above, various surface treatments for the cylindrical base material can be provided. For example, (a) treatment for imparting hydrophilicity to the surface of the cylindrical substrate (hydrophilization treatment), (b) treatment for imparting hydrophobicity to the surface of the cylindrical substrate (hydrophobization treatment), (c) monomer A process of forming a polymerized film on the surface of the cylindrical base material using a gas containing benzene, (d) coating the monomer solution on the surface of the cylindrical base material, and then performing a plasma treatment on the surface of the cylindrical base material (E) a process for forming a polymerized film by supplying a polymerizable monomer to the inner surface of the cylindrical base material after performing a plasma treatment on the surface of the cylindrical base material, (f) a metal A process of forming a ceramic film such as a metal oxide on the surface of the cylindrical base material using a gas containing a compound containing a metal component such as a hydrogen compound, (g) a process of etching the surface of the cylindrical base material, etc. Can be mentioned. The plasma surface treatment apparatus or the method for producing a surface-treated cylindrical substrate is particularly suitable for a hydrophilic treatment with nitrogen.

EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples etc.
(Evaluation method for hydrophilization treatment)
Hydrophilicity was evaluated by the water droplet contact angle. A method for measuring the contact angle between the inner surface and the outer surface of the cylindrical substrate is shown in FIG.

After dropping 1 to 2 μl of water droplets onto the measurement sample, the water droplet contact angle was measured according to the definition defined in FIG. For the measurement, a contact angle meter (CA-X type) manufactured by Kyowa Surface Science Co., Ltd. was used. In this case, the contact angle is obtained by image analysis from the observation image of the droplet. Specifically, it is assumed that the shape of the droplet and the substrate can be approximated as a part of a circle, and the contact angle is calculated by designating three points, both ends and the upper end of the bottom surface of the droplet. In this method, Θ ₁ and Θ ₂ shown in FIG. 3 can be obtained. From the measurement results of Θ ₁ and Θ ₂ for the same observation image, the water droplet contact angle of the cylindrical substrate was calculated.

  For each sample of the example, the water droplet contact angle is measured on the treatment surface side one by one for a total of 10 measurement samples obtained by dividing the cylindrical substrate into 4 mm widths and dividing each into half. Judgment was made as follows from the measurement results of a total of 10 points.

    Average value: It is said that the average value of 10 points is particularly good when it is 25 ° or less.

    Variation: Difference between the maximum and minimum values of 10 measured values. It can be said that it is particularly good when it is 10 ° or less.

[Example 1]
The plasma surface treatment apparatus used in Example 1 is shown in FIG. The electrode portion is shown in the form of a cross-sectional view. This discharge plasma processing apparatus is designed for the inner surface treatment of a cylindrical plastic substrate 3 having an outer diameter of 6.0 mm, an inner diameter of 4.0 mm, and a length of 20 mm.

  A copper ring having an inner diameter of 6.2 mm and a width of 16 mm was used as the outer electrode 1, and a stainless steel rod having an M4 screw groove (JIS B0205-1: 2001) was used as the inner electrode 2. The outer diameter (maximum part) of the inner electrode 2 is 3.98 mm. In this case, the inner electrode 2 is formed with spiral grooves, the interval between the grooves is 0.7 mm, the depth of the grooves is about 0.4 mm, and the width of the grooves is about 0.6 mm. Both electrodes are arranged so as to face each other on the same axis. By forming a spiral groove in the inner electrode, gas can flow along the electrode groove, and a gas flow path is secured in the electrode itself.

  A cylindrical base material 3 made of high-density polyethylene (HDPE) was inserted into the outer electrode 1 and fixed with electrically insulating fixtures 71 and 72, and the inner electrode 2 was inserted. From the electrically insulating fixture 71 side, gas was introduced between the inner electrode 2 and the cylindrical substrate 3 through the valve 11 and the gas introduction pipe 10. A 13.56 MHz high-frequency power source 5 capable of time modulation was connected between the outer electrode 1 and the inner electrode 2 via a matching unit 4, and the inner electrode 2 was electrically grounded. Nitrogen gas was used as the gas, and the flow rate was 0.5 l / mmin. It was. The time modulation condition of the high frequency power source is a modulation frequency of 600 Hz, a duty ratio (ratio of a period during which the high frequency power is applied in the modulation cycle) 0.01, and an input power during the period during which the high frequency power is applied is 30 W, A discharge plasma treatment was performed for 300 seconds. The pressure during the treatment was 0.10 MPa. The time-averaged input power is 0.3 W obtained by multiplying the input power during the period when the high-frequency power is applied by the duty ratio. The results are shown in Table 1.

  The average value of the contact angle was 17.4 deg and was sufficiently hydrophilic. Processing variation was as small as 6.1 deg, and uniform processing was performed.

  In addition, from the observation of the state of the discharge plasma observed between the substrate and the electrode during the treatment, uniform light was observed along the periphery of the electrode.

[Example 2]
Example 1 except that an electrode rod having an outer diameter of 3.95 mm, an interval between the grooves of 0.7 mm, and a linear groove parallel to the axial direction was used as the inner electrode 2 (see FIG. 4). Similarly, discharge plasma treatment of the inner surface of the HDPE substrate was attempted. The depth of the groove formed on the electrode is about 0.25 mm, the width of the groove is about 0.5 mm, and a total of 18 grooves are formed on the inner electrode. In this case, by forming a groove parallel to the axial direction in the inner electrode, a gas flow is possible along the electrode groove, and a gas flow path is secured in the electrode itself. The results are shown in Table 1.

  The average value of the contact angle was 14.7 deg and was sufficiently hydrophilic. Processing variation was as small as 2.8 deg, and uniform processing was performed.

  Further, from the visual observation of the discharge plasma seen from between the substrate and the electrode during the treatment, homogeneous light was observed along the periphery of the electrode.

Example 3
Example 1 except that an electrode rod having an outer diameter of 3.95 mm, an interval between the grooves of 1.0 mm, and a linear groove parallel to the axial direction was used as the inner electrode 2 (see FIG. 4). Similarly, discharge plasma treatment of the inner surface of the HDPE substrate was attempted. The depth of the groove formed on the electrode is about 0.4 mm, the width of the groove is about 0.8 mm, and a total of 12 grooves are formed on the inner electrode. In this case, by forming a groove parallel to the axial direction in the inner electrode, a gas flow is possible along the electrode groove, and a gas flow path is secured in the electrode itself. The results are shown in Table 1.

  The average value of the contact angle was sufficiently hydrophilized at 20.2 deg. Processing variation was as small as 5.8 deg, and uniform processing was performed.

  Further, from the visual observation of the discharge plasma seen from between the substrate and the electrode during the treatment, homogeneous light was observed along the periphery of the electrode.

[Comparative Example 1]
Except for using an electrode rod having an outer diameter of 3.18 mm and a flat surface as the inner electrode 2 (see FIG. 5), the discharge plasma treatment of the inner surface of the HDPE substrate was attempted in the same manner as in Example 1. . In this case, gas flow is possible, but since the surface is flat, a gas flow path is not secured in the electrode itself. The results are shown in Table 1. In this case, discharge plasma could not be formed.

Example 4
Example 1 except that an electrode rod having an outer diameter of 3.95 mm, an interval between the grooves of 4.0 mm, and a linear groove parallel to the axial direction was used as the inner electrode 2 (see FIG. 6). Similarly, discharge plasma treatment of the inner surface of the HDPE substrate was attempted. The depth of the groove formed in the electrode is about 0.5 mm, the width of the groove is about 1.0 mm, and a total of three grooves are formed in the inner electrode. In this case, by forming a groove parallel to the axial direction in the inner electrode, a gas flow is possible along the electrode groove, and a gas flow path is secured in the electrode itself. The results are shown in Table 1.

[Comparative Example 2]
HDPE was carried out in the same manner as in Example 1 except that an electrode rod having an outer diameter of 3.95 mm, an interval between grooves of 1.0 mm, and grooves formed in the circumferential direction was used as the inner electrode 2 (see FIG. 7). An attempt was made to perform a discharge plasma treatment on the inner surface of the manufactured substrate. The depth of the groove formed in the electrode is about 0.5 mm, the width of the groove is about 0.8 mm, and a total of 20 grooves are formed in the circumferential direction on the inner electrode. In this case, the inner diameter of the substrate 3 and the outer diameter of the inner electrode 2 are very close, and a gas flow path is not secured in the electrode itself, so that the pressure loss is high and it is not easy to flow the gas. The results are shown in Table 1. In this case, as in Comparative Example 1, discharge plasma could not be formed.

[Comparative Example 3]
A non-conductive spacer 4 having a thickness of 0.32 mm and a width of 1 mm of polyimide resin attached to an electrode rod having an outer diameter of 3.18 mm and a flat surface in parallel with the axial direction at an interval of 3.3 mm between the spacers. Was used as the inner electrode 2 (see FIG. 8), and a discharge plasma treatment was performed on the inner surface of the HDPE substrate in the same manner as in Example 1. In this case, gas flow is possible, but since the electrode surface is flat, no gas flow path is secured in the electrode itself. The results are shown in Table 1. In this case, discharge plasma could not be formed.

(Discussion)
When an axial groove is provided in the electrode, uniform discharge plasma is generated and a hydrophilic treatment can be performed. In particular, as in Examples 1 to 3, it was found that when fine grooves with small intervals between the grooves were formed on the surface, the hydrophilization treatment was sufficient and there was little variation.

  According to the present invention, it is possible to provide a device having a more uniform surface treatment than in the past with a simpler structure, and moreover, the cylindrical base material obtained by surface treatment with the device is more Since it has a homogeneous treatment surface, it is extremely valuable industrially.

It is a schematic sectional drawing of the plasma surface treatment apparatus (used in Example 1) which concerns on one Embodiment of this invention. It is a schematic sectional drawing of the plasma surface treatment apparatus which concerns on other embodiment of this invention. It is a figure explaining the identification method of the water droplet contact angle of a cylindrical base material. It is the schematic of the electrode part (used by Example 2, 3) of the plasma surface treatment apparatus which concerns on other embodiment of this invention. 3 is a schematic view of an electrode portion of the plasma surface treatment apparatus used in Comparative Example 1. FIG. It is the schematic of the electrode part (used in Example 4) of the plasma surface treatment apparatus which concerns on other embodiment of this invention. It is the schematic of the electrode part of the plasma surface treatment apparatus used in the comparative example 2. 6 is a schematic view of an electrode portion of a plasma surface treatment apparatus used in Comparative Example 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Outer electrode 1a ... Helical groove | channel 2 formed in the inner surface of an outer electrode ... Inner electrode 2a ... Spiral groove | channel 3 formed in the surface of an inner electrode ... Cylindrical base material 4 ... Matching device 5 ... Power supply 6 ... Non-conductive spacers 71, 72 ... Fixing tool 10 ... Gas pipe 11 ... Valve

Claims (11)

  In a coaxial plasma surface treatment apparatus having an outer electrode of a cylindrical substrate arranged coaxially and an inner electrode arranged to face the outer electrode via the cylindrical substrate, Both of the electrodes are made of a conductive material, and a groove capable of flowing gas in the axial direction is formed on the surface of the electrode on the plasma surface treatment side of these electrodes, so that the electrode is made of the conductive material. A plasma surface treatment apparatus for a cylindrical substrate, wherein the surface of the electrode is an uneven surface.   The plasma surface treatment apparatus according to claim 1, wherein an interval [p (mm)] between the grooves is an interval of 0.1 to 3.0 mm. Assuming that the interval between the grooves is p (mm), the depth of the grooves is 0.1 × p to 1.0 × p (mm), and the width is 0.5 × p to 1.0 × p (mm). The plasma surface treatment apparatus according to claim 1.   The plasma surface treatment apparatus according to claim 1, wherein the electrode on the plasma surface treatment side is an inner electrode.   The plasma surface treatment apparatus according to claim 1, wherein the cylindrical substrate has an inner diameter of 1 to 10 mm and a thickness of 0.1 to 5 mm.   2. The plasma surface treatment apparatus according to claim 1, wherein the groove has a structure that is continuous in a certain direction from one end of the electrode to the other end along the axis.   A method for producing a surface-treated cylindrical base material, wherein the surface treatment is performed using the plasma surface treatment apparatus according to claim 1.   The method for producing a surface-treated cylindrical substrate according to claim 7, wherein the plasma surface treatment is a treatment under a pressure of 0.01 to 0.12 MPa.   The method for producing a surface-treated cylindrical substrate according to claim 7, wherein the cylindrical substrate is a resin.   The method for producing a surface-treated cylindrical substrate according to claim 9, wherein the plasma treatment is a hydrophilic treatment with nitrogen.   The method for producing a surface-treated cylindrical substrate according to claim 7, wherein the cylindrical substrate has an inner diameter of 1 to 10 mm and a thickness of 0.1 to 5 mm.

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