JP2008200991A - Plasma treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma treatment method capable of substantially reducing the unevenness of treatment, especially in the surface-modifying treatment of a fluorine resin having a tendency of often causing the unevenness of the treatment. <P>SOLUTION: The plasma treatment method comprises steps of forming a pressure atmosphere with a specified gas in a treatment space in which a target material is put to raise the atmosphere to pressure higher than the outside of the treatment space for generating plasma, and plasma-treating the surface of the target material in the treatment space. The pressure atmosphere is formed by displacing air in the treatment space with specified gas and injecting the specified gas until the pressure of the inside of the treatment space becomes higher than that of the outside of the treatment space and generating plasma. The gas displacement is carried out by evacuating the treatment space and injecting the specified gas into the treatment space. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a surface modification treatment aimed at improving the hydrophilicity and adhesiveness of the surface of a difficult-to-adhere base material having poor hydrophilicity such as a fluororesin. The present invention relates to a plasma processing method for performing surface modification by processing.

  Conventionally, glow plasma treatment, which is a dry and clean treatment method, is known as a surface modification method (surface treatment method) for treating the surface of a substrate to impart hydrophilicity, adhesion, and the like to the surface.

  As surface treatment with glow plasma, low-pressure glow plasma treatment has been generally used, but in the case of low-pressure glow plasma treatment, since it is usually performed at a low pressure of 1.3 kPa or less, a large vacuum is used for the implementation. An apparatus is required, and there is a drawback that equipment costs and processing costs are increased, and heat is easily generated during processing, and it is difficult to apply to an object to be processed made of a low melting point material.

As a processing method for solving the drawbacks of the low-pressure glow plasma processing as described above, a processing method by an atmospheric pressure glow plasma method in which plasma processing is performed at atmospheric pressure has been developed. A treatment method for improving the adhesion of the surface has been proposed. (Patent Document 1)
JP-A-4-145139

  However, in the conventional atmospheric pressure plasma treatment, the surface modification effect is not sufficient, and a lot of treatment unevenness occurs on the object to be treated. In particular, in the surface modification treatment of the fluororesin such as the hydrophilic treatment of the surface of the fluororesin when a large area is treated, the effect of improving the adhesiveness is insufficient, and the occurrence of treatment unevenness is remarkable.

For this reason, there has been a demand for an atmospheric pressure plasma processing method capable of greatly reducing processing unevenness, and particularly capable of reducing processing unevenness even in the surface modification treatment of a fluororesin that easily causes processing unevenness.
Note that the treatment unevenness referred to here means quality variation (in-plane variation) related to hydrophilicity and adhesiveness within the surface of a single object to be processed, and between objects to be processed when a plurality of objects to be processed are processed. This is a variation in quality.

  As a result of intensive studies on the cause of processing unevenness in the conventional atmospheric pressure plasma processing, the present inventors have found that if air exists in the processing space, the efficiency of the plasma processing is poor and the effect of improving adhesiveness is insufficient, and further, the processing Ascertaining the occurrence of unevenness and cutting off the intrusion of air into the processing space, it has been found that the plasma treatment efficiency can be improved and the effect of improving adhesion can be improved, and further, the processing unevenness can be greatly reduced, leading to the present invention. It was.

The invention described in claim 1
Plasma treatment is performed on the surface of the object to be processed in the processing space by setting the inside of the processing space in which the object to be processed is placed to a pressure atmosphere higher than the outside of the processing space with a predetermined gas and generating plasma. It is the plasma processing method characterized.

In the plasma processing according to the present invention, the processing space in which the object to be processed is disposed is made higher than the surrounding processing space (hereinafter simply referred to as “ambient”) with a predetermined gas and a pressure atmosphere that generates plasma. Since air is prevented from entering the processing space, it is possible to increase the efficiency of the plasma processing to increase the effect of improving adhesion, and to perform plasma processing with greatly reduced processing unevenness.
In addition, in the invention of this claim, in order to increase the plasma processing efficiency and improve the adhesion improvement effect, and further reduce the processing unevenness, the plasma is generated higher than the surrounding with a predetermined gas. It is possible to carry out by a simple method of setting a pressure atmosphere.

  The present inventor further examined the pressure atmosphere that generates a plasma higher than the surrounding with the above-described predetermined gas, and found that the present invention can be applied to the conventional low-pressure plasma treatment. That is, it has been found that by preventing air from entering the processing space, the efficiency of the plasma processing can be improved to improve the adhesion improvement effect, and the processing unevenness can be greatly reduced.

The predetermined gas in this claim may be any gas except air and suitable for plasma generation, and is not particularly limited. For example, an inert gas such as He, Ne, Ar, N ₂ or the like It is a gas in which a small amount of CO ₂ , halogen, or other gas is mixed, which contains an inert gas as a main component and reacts with the object to be treated to give a hydrophilic functional group or hydroxyl group to the surface of the object to be treated.

  As a method of creating a pressure atmosphere in the processing space that is higher than the surroundings and that generates plasma, the processing space is sealed, and the predetermined gas such as He has a pressure in the processing space that is higher than the surroundings and generates plasma. Although it may be injected into the processing space until the pressure is reached, the predetermined gas is moved from one end to the other end of the processing space while maintaining the processing space at a pressure atmosphere higher than the surrounding with the predetermined gas and generating plasma. When plasma treatment is performed while flowing, more stable plasma treatment can be performed.

  Means for generating plasma include discharge such as corona discharge and arc discharge in addition to glow discharge, and means for generating plasma is not particularly limited in the present invention, but from the point that processing unevenness can be further suppressed. Glow discharge is preferred. Here, in order to perform glow discharge in a pressure atmosphere above a certain pressure, it is necessary to cover the surface of at least one electrode with a solid dielectric, and ceramic, glass, plastic, etc. are applied as the solid dielectric. The material is not particularly limited, but ceramic or glass having a high dielectric constant is preferable.

Invention of Claim 2 is the said plasma processing method, Comprising:
In the method of creating a pressure atmosphere in which the predetermined gas is higher than the outside of the processing space and generates plasma, the pressure in the processing space is increased outside the processing space after the air in the processing space is replaced with the predetermined gas. The plasma processing method is characterized in that the predetermined gas is injected into the processing space until the pressure is higher and pressure for generating plasma.

According to the invention of this claim, before the predetermined gas is injected into the processing space to obtain a pressure atmosphere that is higher than the surroundings and generates plasma, the air in the processing space is temporarily replaced with the predetermined gas. The air in the processing space can be completely removed, and a pressure atmosphere suitable for realizing plasma processing with extremely little processing unevenness can be formed.
Specifically, for example, a predetermined gas is injected from one end of the processing space prior to the plasma processing, and the air in the processing space is completely removed, so that the processing space is only in a predetermined gas state. be able to.

Invention of Claim 3 is said plasma processing method, Comprising:
The method of substituting with the predetermined gas is a plasma processing method characterized in that the predetermined gas is injected into the processing space after evacuating the processing space.

  According to the invention of claim 3, since the atmosphere remaining in the processing space can be eliminated in a short time as compared with the method of performing gas replacement by flowing an atmospheric gas into the processing space, it is simple and quick. Therefore, it is possible to form a pressure atmosphere suitable for realizing plasma processing with less processing unevenness. Further, since the atmosphere gas is not consumed when the gas in the sealed space is replaced, it is economically excellent.

Note that the evacuation referred to here includes evacuating the atmosphere remaining in the processing space as much as possible, but evacuation to 2.6 × 10 ⁻² MPa or less is preferable.

Invention of Claim 4 is said plasma processing method, Comprising:
The processing space is formed using a cylinder, and the plasma processing is performed using the cylinder as a ground electrode or an application electrode.

  In the invention of this claim, at least one of the ground electrode or the applied electrode of the discharge electrode for generating plasma is a cylindrical electrode, and the other electrode that forms a counter electrode with the cylindrical electrode is the cylindrical electrode. The plasma is generated inside the cylindrical electrode by disposing it between the two electrodes and discharging between the two electrodes.

  In the invention of this claim, since plasma is generated inside the cylindrical electrode, the plasma wraps around the side surface or back surface (surface not facing the electrode) of the object to be processed, and has a shape such as a columnar shape that is not flat. Plasma treatment can be performed uniformly on the workpiece.

  In addition, for example, when processing a surface layer such as an endless belt or a roller for an image forming apparatus such as a multilayer belt or a roller, a cylindrical or tubular object to be processed is disposed along the inner surface of the cylindrical electrode. Plasma processing can be easily performed by disposing the other electrode that is opposite to the electrode inside the workpiece.

  In the invention of this claim, the shape of the other electrode is not particularly limited, but the other electrode is also a cylindrical electrode, and is arranged so that the axial centers of both cylindrical electrodes overlap (hereinafter referred to as the other electrode). (Also referred to as a double cylinder system) is preferable because glow plasma is uniformly generated over the entire space sandwiched between both cylindrical electrodes. Furthermore, in the double cylinder system, for example, even when the diameter of the outer cylindrical electrode is fixed, the distance between the two electrodes can be freely adjusted by adjusting the diameter of the inner cylindrical electrode. By reducing the distance between the two cylindrical electrodes, the plasma can be generated by discharging with a low applied voltage. Further, it is not necessary to provide an outer cylindrical electrode for each diameter of the object to be processed.

Invention of Claim 5 is the said plasma processing method, Comprising:
The plasma processing is a plasma processing method, wherein the pressure in the processing space is performed under a pressure higher by 0.1 kPa or more than the pressure outside the processing space.

  In the present invention, it is preferable that the pressure of the atmospheric gas in the processing space is higher by 0.1 kPa or more than outside the processing space. When the pressure of the atmospheric gas in the processing space is set to the above-mentioned pressure, air can be surely prevented from entering the plasma processing space, and plasma can be stably generated. Therefore, it is possible to perform plasma processing with high and less processing unevenness.

Invention of Claim 6 is the said plasma processing method, Comprising:
The plasma treatment method is characterized in that the object to be treated is a resin selected from a fluororesin, a polyethylene terephthalate resin, and a polyphenylene sulfide resin.

In the invention of this claim, the effect of the present invention can be remarkably exerted in the surface modification treatment of a fluororesin which has conventionally been difficult to prevent the occurrence of processing unevenness of the workpiece.
In the invention of this claim, the fluororesin that is the object to be processed is not particularly limited. For example, polytetrafluoroethylene (PTFE) suitable as a surface layer of a multi-layer endless belt or roller for image transfer or fixing of the image forming apparatus, Examples thereof include tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA).
Further, the fluororesin in the present invention includes a fluorine-containing resin composition in which other substances such as a plasticizer and a filler are added to the fluororesin in addition to a pure fluororesin.

  Moreover, the invention of this claim can also exhibit the effect remarkably also in the polyethylene terephthalate (PET) resin and polyphenylene sulfide (PPS) resin used for an electronic material. That is, when the accelerated plasma (ions) collides with the resin surface, the adhesion of the ink during printing is improved and the printability is improved.

  According to the present invention, it is possible to increase the efficiency of the plasma processing on the object to be processed to increase the adhesive improvement effect, and to perform the plasma processing in which the processing unevenness is greatly reduced.

  Hereinafter, the present invention will be described based on the best mode by taking a transfer belt for an image forming apparatus as an example. Note that the present invention is not limited to the following embodiments. Various modifications can be made to the following embodiments within the same and equivalent scope as the present invention.

(Embodiment 1)
(A) Formation of surface layer First, formation of the surface layer of a transfer belt for an image forming apparatus, which is an object to be subjected to plasma treatment in the present embodiment, will be described.
FIG. 1 is a diagram conceptually illustrating a method for forming the surface layer 3 of the transfer belt according to the present embodiment. In FIG. 1, reference numeral 4 denotes a first cylindrical electrode. The first cylindrical electrode 4 is an electrode made of stainless steel having an inner diameter of 169.2 mm, a length of 500 mm, and a predetermined thickness. A predetermined amount of PFA dispersion (PFA grade 950HP) manufactured by Mitsui Dupont Fluoro Chemical Co. was applied to the inner peripheral surface of the first cylindrical electrode 4 and then baked at 400 ° C. on the inner surface of the first cylindrical electrode 4. A surface layer 3 having a length of 470 mm and a thickness of 8 μm was formed.

(B) Surface Plasma Treatment Secondly, the surface layer plasma treatment will be described.
In the present invention, the plasma treatment is performed under a pressure atmosphere with a predetermined gas and a pressure higher than the ambient pressure. By making the atmosphere in which the plasma treatment is performed higher than the ambient pressure, it is possible to prevent air from entering the plasma treatment chamber, which is a treatment space in which the plasma treatment is performed during the treatment, and to reduce treatment unevenness. . Hereinafter, the plasma processing in the present invention will be described by taking three specific forms.

(B-1) First embodiment a. In the present embodiment, two large and small cylindrical electrodes having different diameters are arranged so that their axes coincide with each other, and air is supplied in a predetermined manner. By continuing to inject a predetermined gas (He gas) after replacement with gas (He gas), high-frequency power is applied between both cylindrical electrodes in a state where the pressure is higher than the surrounding pressure (atmospheric pressure). This is applied to generate glow plasma in a space (hereinafter also referred to as a plasma generation region) between the two cylindrical electrodes, and plasma treatment of the surface layer 3 disposed in the same space is performed. According to this embodiment, when performing plasma processing on a cylindrical workpiece having a large diameter, the distance between both electrodes can be reduced, and glow plasma can be generated with a low applied voltage.

This embodiment will be specifically described below. 2 and 3 are diagrams conceptually showing how the surface layer 3 according to the first embodiment is subjected to the plasma treatment. FIG. 2 is a front view. FIG. 3 is a diagram conceptually showing a shape when the position indicated by AA ′ is viewed in an arrow.
In FIG. 2, reference numeral 13 denotes a plasma processing chamber surrounded by a second pressure vessel 12 made up of a cylindrical vessel and a lid.

  Inside the plasma processing chamber 13, a second cylindrical electrode having the same length as the first cylindrical electrode 4 and an outer diameter of 152 mm is smaller than the inner diameter of the first cylindrical electrode 4. 11 is installed. Next, the 1st cylindrical electrode 4 which formed the surface layer 3 in the internal peripheral surface is installed so that the 2nd cylindrical electrode 11 may be surrounded. At the same time when the first cylindrical electrode 4 is installed, the first cylindrical electrode 4 is positioned so that the axis of the first cylindrical electrode 4 and the axis of the second cylindrical electrode 11 coincide with each other. The two cylindrical electrodes having different diameters form a double cylinder, and the surface layer 3 is disposed between the two cylindrical electrodes.

  The second cylindrical electrode 11 is connected to one electrode of the high-frequency power source 20 installed outside, and the first cylindrical electrode 4 is grounded. As shown in FIG. 3, the first cylindrical electrode 4 includes a stainless steel cylinder 41, and the second cylindrical electrode 11 includes an aluminum cylinder 111 and a Pyrex having an outer peripheral surface of 4 mm in thickness. The solid dielectric 112 is covered with glass (manufactured by Asahi Techno Glass).

  An air supply pipe 14 for supplying a predetermined gas to the plasma processing chamber 13 and a vacuum exhaust pipe 18 for evacuating the gas from the plasma processing chamber 13 are attached to the lid of the second pressure vessel 12. A valve 15 and a valve 19 are attached to the air supply pipe 14 and the vacuum exhaust pipe 18, respectively. Further, an exhaust pipe 16 for releasing the gas in the plasma processing chamber 13 to the outside is attached to the wall of the second pressure vessel 12, and a valve 17 is attached to the exhaust pipe 16. The supply pipe 14 is connected to a high-pressure cylinder (not shown) for a predetermined gas (He gas), and the vacuum exhaust pipe 18 is connected to a second vacuum pump 21.

  The valve 15 and the valve 17 are closed, the valve 19 is opened, the second vacuum pump 21 is operated, and the air in the plasma processing chamber 13 is supplied to an HNT-221A type pressure gauge (pressure range manufactured by Daiichi Keiki Seisakusho). : Centering on atmospheric pressure, −0.1 MPa to 0.1 MPa) (not shown) is excluded until it indicates −0.1 MPa. Next, the valve 19 is closed, the valve 15 is opened, and a predetermined gas (He gas) is supplied from the supply pipe 14 to the plasma processing chamber 13 at a flow rate of 10 l / min. After the pressure in the plasma processing chamber 13 becomes higher than the ambient pressure (atmospheric pressure), the valve 17 is turned on while supplying a predetermined gas (He gas) from the valve 15. The gas inside the plasma processing chamber 13 can be discharged to the outside by slightly opening it. That is, the degree of opening of the valve 17 is adjusted so that the pressure in the plasma processing chamber is maintained higher than the ambient pressure (atmospheric pressure). When the pressure in the plasma processing chamber 13 was measured, it was 0.3 kPa higher than the surrounding pressure (atmospheric pressure).

  Next, a high frequency power of 700 W, voltage 30 kV, frequency 20 kHz is continuously applied between the cylindrical electrodes 4 and 11 for 60 seconds to generate glow plasma in the space between the cylindrical electrodes 4 and 11. The plasma treatment of the surface layer 3 was performed. As described above, since the pressure in the plasma processing chamber 13 is set higher than the surrounding pressure (atmospheric pressure), the intrusion of outside air into the plasma processing chamber 13 is prevented, so that high-frequency power is applied. During this period, it was confirmed that a stable glow plasma was generated over the entire plasma generation region.

b. Surface layer characteristic evaluation Three samples were prepared as means for evaluating the adhesion of the surface layer 3 subjected to the plasma treatment in the first embodiment, and the contact angle when water droplets were placed on the surface was determined as Kyowa Interface Chemical Co., Ltd. It measured using the CA-X150 type contact angle meter made from.
Measure the contact angle of a total of 12 points of 4 points in the circumferential direction x 3 points in the axial direction for each sample, and use the average value as a measure of adhesion, and the difference between the maximum value and the minimum value is the in-plane variation. It was set as the scale which shows a magnitude | size.
The results are shown in Table 1.

Next, a comparative form to be compared with the first embodiment will be described.
(B-2) Comparative form a. Plasma processing in which the pressure in the plasma processing chamber is set equal to the ambient pressure In the first embodiment, the valve 17 attached to the exhaust pipe 16 is fully opened, and the pressure in the plasma processing chamber is equal to the ambient pressure (atmospheric pressure). Except for the above, plasma treatment of the surface layer 3 was performed in the same manner as in the first embodiment.

b. Characteristics Evaluation Thereafter, the characteristics of the obtained surface layer were evaluated as in the first embodiment.
The results are shown in Table 1.

(B-3) Surface layer test results Table 1 is a table showing the surface layer test results according to the first embodiment and the comparative embodiment.

  As shown in Table 1, in the case of 1st Embodiment, it turned out that the average value of a contact angle was small compared with the comparison form, and the adhesive improvement effect was heightened. Further, good test results were obtained with small in-plane variation in contact angle in one sample. Furthermore, good results were also obtained in that the difference between the average values of the contact angles of the three samples was small. Thus, good test results were obtained because, in the first embodiment, the pressure in the plasma processing chamber was set higher than the surrounding pressure (atmospheric pressure) during the plasma processing. This is considered to be because air can be prevented from entering the plasma processing chamber, so that glow plasma can be stably generated, and the efficiency of the plasma processing is enhanced.

Next, other desirable embodiments will be described as a second embodiment and a third embodiment.
(C) Second embodiment a. In this embodiment, a cylindrical electrode is used for one electrode (outer electrode) for generating glow plasma, and two electrodes are used for the other electrode (inner electrode). Using the above-mentioned inner side electrode, while rotating the inner side electrode around the rotation axis arranged at the axial center of the cylindrical electrode, under a pressure atmosphere with the same gas and the same pressure as the first embodiment High frequency power is applied between both electrodes to generate glow plasma in the space between both electrodes, and plasma treatment of the surface layer 3 disposed in the same space is performed. According to the present embodiment, since the inner electrode is rotated around the axis of the cylindrical electrode, the entire processing surface of the cylindrical workpiece can be processed even with the inner electrode of a small area. it can. This embodiment will be specifically described below.

  In the first embodiment, an apparatus including a rotary inner electrode is used instead of the second cylindrical electrode 11, and the time during which the plasma processing surface of the surface layer 3 is exposed to glow plasma is the first time. The processing time is adjusted to be the same as the embodiment. Further, the output of the high frequency power to be applied is adjusted according to the size of the inner side electrode. Except for this, plasma processing is performed as in the first embodiment.

FIG. 4 is a diagram conceptually showing the state of the plasma processing in the second embodiment, and FIG. 5 conceptually shows the shape when the portion indicated by AA ′ in FIG. FIG. 4 and 5, reference numeral 22 denotes an inner electrode, and the inner electrode 22 has the same length as the first cylindrical electrode 4 as shown in FIG. 4 and is joined to a metal rotating shaft 24. The internal electrode support shaft 23 made of metal is held, and the internal electrode 22 and the rotating shaft 24 are in a conductive state.
When viewed from above, as shown in FIG. 5, the inner electrode 22 is composed of four segment-shaped electrodes having an arc having a radius of curvature of 80 mm on the surface facing the first cylindrical electrode 4. Yes. The rotation shaft 24 is disposed at the axial center of the first cylindrical electrode 4, and the angle formed by the direction A and the direction B of the internal electrode support shaft 23 is 90 °. The inner electrode support shaft 23 is extendable in length, and the distance between the inner electrode 22 and the rotating shaft 24 is adjusted to be equal in both the direction A and the direction B. The side electrode 22 is disposed at a position equidistant from the axis of the first cylindrical electrode 4. Note that the distance d between the first cylindrical electrode 4 and the inner electrode 22 is set to 5 mm. A space p between the first cylindrical electrode 4 and the inner electrode 22 is a plasma generation region. FIG. 6 is an enlarged view of the internal electrode 22. The internal electrode 22 includes an aluminum arc-shaped electrode 221 having a thickness of 3 mm and a solid dielectric 222 having a surface covered with glass having a thickness of 3 mm. The rotating shaft 24 of the internal electrode 22 is connected to a motor 25 with a transmission, and is further connected to one electrode of the high frequency power source 20.

  While rotating the inner electrode 22 around the rotating shaft 24 at a speed of 10 rpm, an output of 500 W, a voltage of 35 kV, and a high frequency power of 30 kHz are applied for 30 seconds between the first cylindrical electrode 4 and the inner electrode 22. Then, the plasma treatment of the surface layer 3 is performed by generating glow plasma in the space between both electrodes.

(D) Third embodiment a. Intermittent plasma treatment In this embodiment, a predetermined predetermined frequency is constantly applied by applying high-frequency power between both electrodes under a pressure atmosphere with the same pressure as that of the first embodiment. Plasma treatment is performed by generating glow plasma in a gas atmosphere. Specifically, plasma is generated in synchronism with the time for applying high-frequency power to the time during which a predetermined gas passes through the workpiece.

By synchronizing the time when the predetermined gas passes through the object to be processed, that is, by applying the gas intermittently while turning off the application during the time when the predetermined gas passes through the object to be processed, the inside of the processing space is always fresh. Since plasma is generated by applying in a predetermined gas atmosphere state, the activity of the predetermined gas can be kept substantially constant during the plasma processing, and processing unevenness (in-plane variation) Can be reduced.
This embodiment will be specifically described below.

  In the first embodiment, high frequency power is intermittently applied to both cylindrical electrodes, and plasma is generated only during the application. Specifically, 30 cycles (total application time: 60 seconds) are applied, with high-frequency power applied for 2 seconds and applied off for 2 seconds as one cycle. Except for this, plasma treatment of the surface layer 3 is performed in the same manner as in the first embodiment.

  In the second and third embodiments, as in the first embodiment, the plasma processing chamber is set to have a higher pressure than the surrounding pressure during the plasma processing, so that the plasma processing is performed. Since air can be prevented from entering the room, glow plasma can be stably generated, and the efficiency of plasma processing can be increased. Therefore, good test results almost the same as those of the first embodiment can be obtained. It is thought that

(E) Production of transfer belt Next, the surface layer produced in the first embodiment was applied to produce a transfer belt for an image forming apparatus, and performance evaluation was performed.
a. First, the configuration of the transfer belt for the image forming apparatus according to the first embodiment will be described.
The transfer belt is mainly composed of three layers: a base layer responsible for mechanical strength, an intermediate layer for imparting elasticity to the belt, and a surface layer responsible for a transfer function.
FIG. 7 is a diagram conceptually showing the configuration of the transfer belt for the image forming apparatus according to the present embodiment, and is an enlarged view of a part of the cross section of the transfer belt. In FIG. 7, 1 is a base layer based on a polyimide resin, 2 is an intermediate layer composed of an elastomer based on aqueous urethane, and 3 is a surface layer composed of a fluororesin excellent in toner releasing properties. Adjacent layers and layers are bonded. In the transfer belt according to the present invention, the surface layer 3 and the intermediate layer 2 are directly bonded without using an adhesive layer.
The thickness of each layer is 60 μm for the base layer, 200 μm for the intermediate layer, and 8 μm for the surface layer.

b. Next, a procedure for manufacturing the transfer belt according to the present embodiment will be described.
In the present embodiment, the intermediate layer 2 is formed by forming a laminated body in which the base layer 1 and the intermediate layer 2 are laminated, fitting the inner peripheral surface with the surface layer 3 subjected to the plasma treatment, and pressing both. And the surface layer 3 are adhered to form a transfer belt.

The formation of each layer constituting the transfer belt will be described below.
c. Formation of a laminate with a base layer and an intermediate layer laminated While rotating a drum-shaped mold, a predetermined amount of polyimide varnish is applied to the outside, and then the mold is heated to carry out an imidization reaction. A cylindrical base layer 1 made of polyimide resin having a thickness of 60 μm was formed around the mold.
Next, the base layer 1 was once removed from the drum mold and fitted to the outer peripheral surface of another drum mold.
Separately, a thickening agent was added to aqueous urethane to obtain a viscosity of about 10 Pa · s, and a defoamed urethane solution was prepared and applied to the surface of the base layer 1 in a predetermined amount. After coating, moisture was dried at room temperature, and further annealed at 160 ° C. to form an intermediate layer 2 made of polyurethane having a thickness of 200 μm on the surface of the base layer 1 to obtain a cylindrical laminate.
FIG. 8 is a diagram conceptually illustrating a state in which a laminated body including the base layer 1 and the intermediate layer 2 is formed on the outer peripheral surface of the drum-shaped mold 5.

Next, the adhesion between the laminate and the surface layer will be described.
d. Adhesion of Laminate and Surface Layer Here, a specific method of adhering the intermediate layer 2 and the surface layer 3 of the laminate by fitting the laminate to the surface layer 3 and pressing them will be described.
FIG. 9 is a diagram conceptually showing an adhesion process for adhering the intermediate layer 2 and the surface layer 3 by pressing the laminate and the surface layer 3.
In FIG. 9, 6 is a kind of fluid container, which is a hollow cylindrical container (hereinafter referred to as “waterback”) made of a silicon rubber film and closed at both ends. The cylindrical laminate is removed from the drum mold 5 and fitted into the outer periphery of the water bag 6.

  The water bag 6 fitted with the laminated body is inserted inside the first cylindrical electrode 4 having the surface layer 3 formed on the inner peripheral surface, and the water bag 6 and the first cylindrical electrode 4 are connected to the first withstand voltage. It is installed inside the vacuum chamber 7 surrounded by the container 8. Next, the pump 9 is operated to press the fluid into the water bag 6 to raise the water back pressure to 0.5 MPa, and at the same time, the first vacuum pump 10 is operated to make the vacuum chamber 7 vacuum. .

The laminated body on the outer periphery of the water bag 6 and the surface layer 3 on the inner periphery of the first cylindrical electrode 4 by the body portion of the water bag 6 inflated by the internal pressure and the inner surface of the first cylindrical electrode 4 are: They are pressed against each other. Since the water bag 6 is a film made of silicon rubber, the entire resin layer uniformly presses the resin layer against the inner surface of the first cylindrical electrode 4. Moreover, since the inside of the vacuum chamber 7 is evacuated at this time, it will be pressed more effectively. As a result, the intermediate layer 2 and the surface layer 3 are firmly bonded. However, as described above, in the present embodiment, the plasma treatment is performed on the inner peripheral surface of the surface layer 3 prior to pressing.
In this way, a transfer belt comprising three layers of the base layer 1, the intermediate layer 2, and the surface layer 3 was obtained.

(F) Evaluation and Evaluation Result of Transfer Belt Next, the evaluation result of the transfer belt to which the surface layer according to the first embodiment is applied will be described.
a. Evaluation method of transfer belt In order to evaluate the transfer belt, a peeling test between a surface layer and an intermediate layer was performed. This is because the quality of the plasma treatment appears in the adhesive force between the surface layer and the intermediate layer as the physical property of the transfer belt as the final product. When the adhesive force is weak, the transfer belt surface layer peels off due to bending during continuous use. As the minimum peeling force, 0.2 kg / 1.5 cm is known to be necessary by an actual machine test.
As a specific test method, a slit was made in the surface layer with a width of 1.5 cm, the surface layer was peeled off from the end portion, and the adhesive force was measured.
Moreover, as a durability test, the presence or absence of abnormalities such as peeling was measured using a bending durability tester. The number of samples is 3 for each test.

b. Results of evaluation of transfer belt As a result of the peeling test, all of the transfer belts according to the first embodiment exceeded the measurement limit (1 kg / 1.5 cm or more), and the minimum peeling force was increased to 0.2 kg / 1.5 cm. It was found that the adhesion was at such a level that it could not be peeled off.
Also, in the durability test, no abnormality such as peeling was observed.

  As described above, it has been found that the transfer belt according to the first embodiment is a transfer belt having excellent adhesion between the surface layer and the intermediate layer and excellent durability.

  As described above, it has been found that extremely good results can be obtained by the plasma treatment according to the present invention. Therefore, the following experiment was conducted in order to investigate the effect of the present invention in more detail.

(G) Experimental example 1: Influence of air mixing on the plasma processing chamber (plasma processing space) The following experiment was conducted to investigate the influence of air mixing on the plasma processing chamber.
a. Plasma Processing In the first embodiment, a mixed gas of He and air is supplied to the plasma processing chamber. The flow rate of He of the gas supplied to the plasma processing chamber was fixed at 10 l / min, and the flow rate of air to be mixed was set at four levels of 0 l / min, 0.02 l / min, 0.1 l / min, and 1 l / min. Other than that, plasma processing of the surface layer was performed under the same conditions as in the first embodiment.

b. Characteristic Evaluation A contact angle of 12 points in total of 4 points in the circumferential direction and 3 points in the axial direction of the obtained sample was measured, and the average value was used as a scale indicating the magnitude of the contact angle.
The results are shown in Table 2 and FIG.

なお、０ｃｃ／分については、第１の実施の形態におけるデータ（３点）を用いた。

The data (3 points) in the first embodiment was used for 0 cc / min.

c. Evaluation Results FIG. 10 shows the relationship between the air mixing amount and the contact angle (average value).
As can be seen from FIG. 10, the contact angle greatly increases with a small amount of air in comparison with the case where the air mixing is zero, and the contact angle increases as the air mixing amount increases. ing.

  As is clear from the above results, if a small amount of air is mixed in the plasma processing space during the plasma processing, the contact angle of the surface layer that is the object to be processed is greatly increased. It can be seen that air can be prevented from invading by a simple method of setting the pressure at a pressure higher than the ambient pressure, and that the effect of improving the adhesiveness can be significantly improved.

(H) Experimental example 2: Effect of evacuation of plasma processing chamber a. Plasma processing When the air in the plasma processing space is replaced with a predetermined gas, the plasma processing is performed with or without excluding the air in the plasma processing chamber prior to supplying the predetermined gas to the plasma processing space. In the first embodiment, after supplying the mixed gas to the plasma processing chamber at a flow rate of 10 l / min for 60 minutes without evacuating the plasma processing chamber in the first embodiment, Plasma treatment was performed as in the first embodiment.

b. Characteristic evaluation Measure the contact angle of 12 points in total, 4 points in the circumferential direction of the surface layer and 3 points in the axial direction, and determine the contact angle (average value) and contact angle R (difference between the maximum value and the minimum value) Comparison was made with the test results of one embodiment. The results are shown in Table 3 and FIGS.

c. Evaluation Results FIG. 11 shows an average value of contact angles (indicated as contact angle in FIG. 11), and FIG. As shown in FIG. 11, in Experimental Example 2 in which the evacuation was not performed, the contact angle was larger than that in the first embodiment in which the evacuation was performed. Further, as shown in FIG. The in-plane variation (contact angle R) of the contact angle is also increased.
As described above, the better result was obtained by performing the evacuation in the first embodiment because the air in the plasma processing chamber was almost completely removed in a short time by performing the evacuation. This is considered to be because the plasma treatment was able to be performed under conditions that hardly existed. On the other hand, in Experimental Example 2, the air in the plasma processing chamber cannot be sufficiently removed only by flowing a predetermined gas into the plasma processing chamber, and the air remains in the plasma processing chamber. Compared to the above embodiment, it is considered that the contact angle is large and the in-plane variation is large.

  According to the present invention, in plasma processing in which plasma processing is performed under a pressure atmosphere that is higher than the surrounding pressure with a predetermined gas, vacuuming is performed prior to replacing the air in the plasma processing chamber with the predetermined gas. Because it can remove the air in the plasma processing chamber in a short time, it removes the air in the plasma processing chamber, improves the adhesion improvement effect, and further reduces the processing unevenness It is.

It is a figure which shows notionally the formation process of the surface layer of the belt for transfer. It is the conceptual diagram which looked at the plasma processing which concerns on the 1st Embodiment of this invention from the front. It is the conceptual diagram which looked at the plasma processing which concerns on the 1st Embodiment of this invention from the upper side. It is the conceptual diagram which looked at the plasma processing which concerns on the 2nd Embodiment of this invention from the front. It is the conceptual diagram which looked at the plasma processing which concerns on the 2nd Embodiment of this invention from the upper side. It is the conceptual diagram which looked at the internal side electrode used for the plasma processing which concerns on the 2nd Embodiment of this invention from the upper side. FIG. 3 is a partially enlarged cross-sectional view of a transfer belt. It is a figure which shows notionally the formation process of the laminated body of the belt for transfer. It is a figure which shows notionally the adhesion process of the surface layer of a transfer belt, and a laminated body. It is a graph which shows the relationship between the mixing amount of air, and a contact angle. It is a graph which shows the relationship between the presence or absence of evacuation, and a contact angle. It is a graph which shows the relationship between the presence or absence of evacuation, and the in-plane variation of a contact angle.

Explanation of symbols

1 Base Layer 2 Intermediate Layer 3 Surface Layer 4 First Cylindrical Electrode 5 Drum Mold 6 Water Back 7 Vacuum Chamber 11 Second Cylindrical Electrode 12 Second Pressure Vessel 13 Plasma Processing Chamber 14 Air Supply Pipe 16 Exhaust Pipe 18 Vacuum exhaust pipe 20 High-frequency power source 21 Second vacuum pump 22 Internal electrode 23 Internal electrode support shaft 24 Rotating shaft 25 Motor

Claims (6)

  Plasma treatment is performed on the surface of the object to be processed in the processing space by setting the inside of the processing space in which the object to be processed is placed to a pressure atmosphere higher than the outside of the processing space with a predetermined gas and generating plasma. A plasma processing method.   In the method of creating a pressure atmosphere in which the predetermined gas is higher than the outside of the processing space and generates plasma, the pressure in the processing space is increased outside the processing space after the air in the processing space is replaced with the predetermined gas. 2. The plasma processing method according to claim 1, wherein the predetermined gas is injected into the processing space until the pressure is higher and a pressure is generated to generate plasma.   The plasma processing method according to claim 2, wherein the method of substituting with the predetermined gas is performed by evacuating the processing space and then injecting the predetermined gas into the processing space.   4. The plasma processing method according to claim 1, wherein the processing space is formed using a cylinder, and the plasma processing is performed using the cylinder as a ground electrode or an application electrode.   5. The plasma processing method according to claim 1, wherein the plasma processing is performed under a pressure higher by 0.1 kPa or more than a pressure outside the processing space.   6. The plasma processing method according to claim 1, wherein the object to be processed is a resin selected from a fluororesin, a polyethylene terephthalate resin, and a polyphenylene sulfide resin.

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