Surface modification method

Abstract

The present invention improves the adhesion of a treated object made of a fluorine-based difficult-to-adhere material. A process gas containing any one or two or more of carbon monoxide, carbon dioxide, hydrogen, water vapor, ethanol, propanol, hexanol, ethylene glycol, ammonia is supplied from a process gas supply section (10) to a plasma generation section (20). In the plasma generation section (20), the process gas is activated by plasma, brought into contact with a treated object (9), and through a reaction based on the contact, the residual proportion of fluorine atoms on the surface of the treated object (9) is made to be 60% or less of that before the contact, and any one or a molecule containing one or more of carbon atoms, hydrogen atoms, oxygen atoms is imparted to the surface of the treated object.

Description

Technical Field

[0001] This invention relates to a method for surface modification of a workpiece made of a difficult-to-bond material, and particularly to a method for surface modification of a fluorine-based difficult-to-bond material containing fluorine atoms. Background Technology

[0002] For example, fluorinated resins such as polytetrafluoroethylene (PTFE) and ethylene-tetrafluoroethylene (ETFE) exhibit low wettability, resulting in poor adhesion of water-based adhesives such as polyvinyl alcohol (hereinafter referred to as "PVA") and polyethers. To improve the adhesion (wetting or hydrophilicity) of such difficult-to-bond fluorinated materials, wet treatment using chemical solutions has been previously employed (see Patent Document 1, etc.), but this requires drainage, leading to high operating costs and environmental impact. Therefore, a dry treatment method has been proposed, where process gases are activated using plasma or similar methods to contact the difficult-to-bond materials (see Patent Document 2, etc.).

[0003] In Patent Document 2, a mixed gas containing water vapor added to inert gases such as helium, argon, neon, and nitrogen is used as the process gas. This process gas is supplied between a pair of electrodes, and a high-frequency voltage of hundreds of kHz to tens of MHz is applied between the electrodes to generate atmospheric pressure plasma, thereby activating the process gas. Simultaneously, the workpiece, made of a fluoropolymer film, is stretched between support rollers on both sides of the pair of electrodes constituting parallel flat plates, and passes through the pair of electrodes. This allows the workpiece to undergo surface modification through plasma irradiation.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 6-228343

[0007] Patent Document 2: Japanese Patent Application Publication No. 2006-294571 Summary of the Invention

[0008] The technical problem that the invention aims to solve

[0009] In the dry plasma treatment described in Patent Document 2, details of the modification process are not shown, and it is unclear how to achieve the desired surface modification degree for fluorine-based, difficult-to-bond materials. In particular, it is believed that insufficient energy supply results in a high residual proportion of fluorine atoms on the surface of the treated material, potentially failing to adequately improve wettability and thus adhesion. Furthermore, in the processing apparatus of Patent Document 2, the treated material is processed while suspended between a pair of electrodes, thus preventing the processing area from expanding due to wrinkles and relaxation, potentially resulting in insufficient processing performance. Additionally, if only one side of the treated material is to be processed, the unwanted side may be processed. On the other hand, if the treated material is transported while in contact with either electrode, damage may occur.

[0010] In view of the above circumstances, the main (first) objective of this invention is to: when dry-treating a workpiece made of a fluorine-based, difficult-to-bond material containing fluorine atoms using plasma, to improve the surface state for obtaining the desired surface modification, thereby significantly improving the wettability of the fluorine-based, difficult-to-bond material and thus improving its adhesion. Furthermore, a second objective of this invention is to minimize the impact of wrinkles and relaxation, and to reliably treat only the desired surface without damaging the workpiece.

[0011] Technical means to solve technical problems

[0012] The inventors conducted in-depth research to solve the aforementioned technical problem and obtained the following insights: by using plasma containing process gases with specific gas components, the wettability of the difficult-to-bond material is improved by setting conditions such that the reduction ratio of the fluorine atom content on the surface of the fluorine-based difficult-to-bond material is within a given range.

[0013] This invention is based on the aforementioned insights and is a method for surface modification of a workpiece made of a difficult-to-bond material containing fluorine atoms. The method comprises: a plasma step, which uses plasma to activate one or more process gases containing carbon monoxide, carbon dioxide, hydrogen, water vapor, ethanol, propanol, hexanol, ethylene glycol, and ammonia, and brings them into contact with the workpiece; and a modification step, which, through a reaction based on the contact, reduces the residual proportion of fluorine atoms on the surface of the workpiece to less than 60% of that before the contact, and imparts molecules containing one or more of carbon, hydrogen, and oxygen atoms to the surface of the workpiece. This significantly improves the wettability of the fluorine-based difficult-to-bond material, thereby improving its adhesion, and achieving the first objective.

[0014] Preferably, the plasma process includes: a generation process that generates a plasma discharge at near atmospheric pressure by applying an electric field to an inter-electrode space divided by a pair of electrodes; a supply process that supplies the process gas to the inter-electrode space; and a contact process that brings the process gas in or through the inter-electrode space into contact with the workpiece.

[0015] Here, near atmospheric pressure refers to 1.013 × 10⁻⁶. 4 Pa ~ 50.663 × 10 4 The Pa range, considering ease of pressure adjustment or simplification of device configuration, is preferably 1.333 × 10⁻⁶. 4 Pa ~ 10.664 × 10 4 Pa, more preferably 9.331 × 10 Pa 4 Pa ~ 10.397 × 10 4 Pa.

[0016] Preferably, the energy input in the plasma process is 0.9 J / cm² relative to the surface area of ​​the workpiece. 2 ~135.0 J / cm 2 .

[0017] If the input energy is less than 0.9 J / cm 2 Otherwise, sufficient surface modification effects of difficult-to-bond materials cannot be obtained.

[0018] If the input energy exceeds 135.0 J / cm³ 2 However, damage to the difficult-to-bond material can actually reduce the bonding strength.

[0019] Preferably, the plasma process includes the process of the object being processed passing through the space between the electrodes.

[0020] Preferably, the plasma process includes applying a pulsed voltage between the pair of electrodes to generate a pulsed plasma at near atmospheric pressure in the space between the electrodes.

[0021] The peak-to-peak voltage of the voltage applied between the pair of electrodes is preferably 3kVpp to 25kVpp, more preferably 12kVpp to 20kVpp, and the frequency is preferably 10kHz to 70kHz, more preferably 20kHz to 55kHz.

[0022] Preferably, the workpiece is in the form of a film, and the pair of electrodes includes a roller-shaped ground electrode and a hot electrode disposed opposite to the ground electrode. In the plasma process, the workpiece is transported by contacting the ground electrode, and plasma at a pressure close to atmospheric pressure is generated between the ground electrode and the hot electrode.

[0023] Preferably, the plasma process includes applying a pulsed voltage between the pair of electrodes to generate a pulsed plasma at near atmospheric pressure in the space between the electrodes.

[0024] By conveying the workpiece in contact with the grounding electrode, scratches on the workpiece can be prevented, and plasma can be applied only to the desired surface of the workpiece for processing, while unwanted surfaces can be left untreated. Furthermore, by increasing the number of electrode pairs consisting of a hot electrode and a roller-shaped grounding electrode, the processing area can be expanded. As a result, quality and performance can be well maintained, achieving the second objective.

[0025] Invention Effects

[0026] According to the present invention, the wettability of the treated material of fluorine-based, difficult-to-bond material can be improved, thereby improving the adhesion, and the desired degree of surface modification can be obtained. Attached Figure Description

[0027] Figure 1 This is a schematic structural diagram showing the surface modification apparatus according to the first embodiment of the present invention.

[0028] Figure 2 This is a schematic structural diagram illustrating the surface modification apparatus according to the second embodiment of the present invention.

[0029] Figure 3 This is a schematic structural diagram illustrating the surface modification apparatus according to the third embodiment of the present invention.

[0030] Figure 4 This is a graph showing the results of the peel strength measurements corresponding to the energy input per unit area in the embodiments.

[0031] Figure 5 This is the spectrum of infrared spectroscopic analysis in the embodiment. Detailed Implementation

[0032] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0033] <First Implementation Method>

[0034] Figure 1 This diagram illustrates the surface modification apparatus 1 according to the first embodiment of the present invention. The workpiece 9 is a difficult-to-bond material containing fluorine atoms. Examples of such difficult-to-bond materials include fluorinated resins such as polytetrafluoroethylene (PTFE) and ethylene-tetrafluoroethylene (ETFE). The shape of the workpiece 9 is not particularly limited; for example, it can be in the form of a film, a plate, or a block.

[0035] The surface modification apparatus 1 improves the adhesion of the workpiece 9 made of the difficult-to-bond material by surface modification, and includes a process gas supply unit 10 and a plasma generation unit 20. The process gas supply unit 10 supplies process gas to the plasma generation unit 20. The process gas contains one or more of the following additives: carbon monoxide, carbon dioxide, hydrogen, water vapor, ethanol, propanol, hexanol, ethylene glycol, and ammonia.

[0036] The additive is added to the carrier gas to generate process gas. As a means of addition, a mass flow controller (MFC) or bubbling can be used.

[0037] Examples of carrier gases include inert gases such as nitrogen (N2). Rare gases can also be used instead of nitrogen as carrier gases. In addition to serving as a carrier gas for transporting process gases containing additives to the plasma generation unit 20 and then to the workpiece 9, the carrier gas also serves as a dilution gas for diluting the additives and as a discharge generation gas in the plasma generation unit 20.

[0038] The plasma generation unit 20 includes a pair of electrodes 21 and 22 and a plasma head 25. A thermal electrode 21 is housed in the plasma head 25. The thermal electrode 21 is formed to face... Figure 1 The paper is orthogonally processed into a long strip extending along its width direction. The dimension of the heat electrode 21 in the width direction is related to the width of the workpiece 9. Figure 1 The dimensions (in the orthogonal direction of the paper plane) are substantially equal to or slightly larger than those of the hot electrode 21. A ground electrode 22 is disposed below the plasma head 25. The ground electrode 22 is formed into a flat plate shape (tablet-shaped) with a processing width dimension equal to that of the hot electrode 21. These electrodes 21 and 22 are positioned vertically opposite each other, forming parallel flat plate electrodes. Solid dielectric layers 21b and 22b are formed on the opposing surfaces of the electrodes 21 and 22, respectively. The solid dielectric layers 21b and 22b are made of ceramics such as alumina. Furthermore, the solid dielectric layers may be disposed on the opposing surfaces of at least one electrode.

[0039] An inter-electrode space 23 is defined between electrodes 21 and 22. Electrodes 21 and 22 are positioned at a pressure close to atmospheric pressure, and the pressure in the inter-electrode space 23 is also close to atmospheric pressure. The gap g in the inter-electrode space 23 is... 23 The distance between the opposing surfaces of the solid dielectric layers 21b and 22b is at least as thick as the material being treated 9, and preferably less than a few millimeters. Figure 1 In the middle, the gap g 23 The size is exaggerated.

[0040] A power supply 24 is connected to the thermoelectrode 21. The grounding electrode 22 is electrically grounded.

[0041] Power supply 24 performs DC-DC conversion on commercial AC power, further converting the DC power into pulsed high-frequency power, which is then supplied to electrode 21. The peak-to-peak voltage of the pulsed voltage applied to electrode 21 is preferably 3kVpp to 25kVpp, more preferably 10kVpp to 16kVpp. Furthermore, the frequency of the pulsed voltage is preferably 20kHz to 55kHz, more preferably 40kHz to 50kHz.

[0042] A gas supply path 13 originating from the process gas supply unit 10 extends toward the plasma generation unit 20. A nozzle 14 at the front end of the gas supply path 13 is held at the plasma head 25 and faces the inter-electrode space 23. Although detailed illustrations are omitted, the nozzle 14 includes a component that directs the gas originating from the gas supply path 13 in the processing width direction (…). Figure 1 The gas diffuser is a gas diffuser that diffuses uniformly in the direction orthogonal to the paper surface.

[0043] The object to be processed 9 is placed on a platform-shaped grounding electrode 22. The grounding electrode 22 also serves as a support for the object to be processed 9. The object to be processed 9 is supported by the grounding electrode 22, which serves as a support, in a manner that allows it to contact the gas within the inter-electrode space 23.

[0044] The surface modification apparatus 1 constitutes a direct plasma treatment apparatus. In this specification, direct plasma treatment refers to surface treatment in which the workpiece 9 is directly exposed to plasma discharge in the inter-electrode space 23 by placing the workpiece 9 in the inter-electrode space 23 or by passing through the inter-electrode space 23.

[0045] A moving mechanism 27 is connected to the plasma head 25 and the thermoelectrode 21. Although detailed illustrations are omitted, the moving mechanism 27 includes a drive unit such as a motor, gears, a timing belt, and other power transmission units. The moving mechanism 27 causes the thermoelectrode 21, the ground electrode 22, and the workpiece 9 to move in a scanning direction orthogonal to the processing width direction. Figure 1 It moves relative to each other in a reciprocating manner (left and right directions).

[0046] It should be noted that the moving mechanism 27 can also be connected to the grounding electrode 22. The grounding electrode 22 can also be moved relative to the plasma head 25.

[0047] The surface modification apparatus 1 described above causes the workpiece 9 to undergo surface modification (surface treatment) as follows.

[0048] <Plasma Process>

[0049] The plasma process and the modification process are performed using a surface modification apparatus 1. In the plasma process, the process gas is activated by plasma and brought into contact with the workpiece 9. Specifically, the plasma process includes a generation process, a supply process, a contact process, and a movement process.

[0050] <Production Process>

[0051] A pulsed voltage is applied between a pair of electrodes 21 and 22 by a preferred pulsed power supply from power source 24. This creates a pulsed electric field within the electrode space 23, generating a plasma discharge (dielectric barrier discharge) close to atmospheric pressure. Pulsed plasma close to atmospheric pressure is preferred.

[0052] <Supply Process>

[0053] In parallel, process gas from process gas supply unit 10 is supplied from nozzle 14 to electrode space 23 via supply path 13.

[0054] <Contact Process>

[0055] Thus, in the inter-electrode space 23 (plasma discharge space), the process gas is activated (including plasmaification, excitation, decomposition, radicalization, and ionization). This activated process gas then comes into contact with the workpiece 9.

[0056] <Moving Process>

[0057] Furthermore, the moving mechanism 27 causes the thermal electrode 21 to move in the scanning direction ( Figure 1 The workpiece 9 moves in the left-right direction. This causes the workpiece 9 to move relative to the electrode space 23 while coming into contact with the activated process gas and being directly exposed to plasma at near atmospheric pressure (atmospheric pressure direct plasma process). Preferably, it is directly exposed to pulsed plasma at near atmospheric pressure (atmospheric pressure direct pulsed plasma process).

[0058] The number of times n is processed when the object 9 moves relatively one way within the inter-electrode space 23 is not limited to one time, but can be multiple times. The object 9 can be processed twice each time by reciprocating, or multiple plasma heads 25 containing thermal electrodes 21 can be set so that the object 9 passes through the inter-electrode space prepared by each plasma head 25 in sequence, thereby making the number of plasma heads 25 correspond to the number of processing times.

[0059] The energy input in the plasma process is preferably 0.9 J / cm² per unit area of ​​the surface of the workpiece 9. 2 ~135.0 J / cm 2When the process gas contains carbon monoxide, carbon dioxide, water vapor, ethanol, propanol, hexanol, ethylene glycol, and ammonia as additives, the input energy is more preferably 5 J / cm³. 2 ~60J / cm 2 Around 10 J / cm², further preferably 10 J / cm² 2 ~30J / cm 2 Approximately. When the process gas contains hydrogen as an additive, the input energy is more preferably 30 J / cm³. 2 ~120J / cm 2 Around 40 J / cm², further optimized to 40 J / cm². 2 ~80J / cm 2 Left and right (reference) Figure 4 (and the embodiments described later).

[0060] The energy input per unit area of ​​the surface of the object being treated 9 is calculated by the following formula (1).

[0061] E(J / cm 2 = Input power (W) × Processing time (sec) / Processing area (cm²) 2 (1)

[0062] The input power (W) is obtained by multiplying the DC voltage (V) and DC current (A) before high-frequency conversion in power supply 24.

[0063] As described above, when the object to be processed 9 is moved relative to one or more plasma heads 25 and processed n times, the energy input per unit area E is calculated by the following formula (2).

[0064] E=ΣPi / vi(i=1,2,…,n) (2)

[0065] Pi is the unit processing width when processing the i-th object 9. Figure 1 The input power (W / cm) per unit length in the orthogonal direction of the paper.

[0066] vi is the relative moving speed (cm / sec) of the i-th processed object 9.

[0067] <Modification Process>

[0068] In each processing batch, a reaction occurs on the surface of the workpiece 9 caused by contact between the surface molecules of the workpiece 9 and the plasma and activated process gas. This breaks the fluorine bonds in the surface molecules of the workpiece 9, separating fluorine atoms from the surface molecules. Consequently, the proportion (atom%) of fluorine atoms in the atoms constituting the surface of the workpiece 9 is reduced. Furthermore, carbon atoms, hydrogen atoms, oxygen atoms, etc., originating from the process gas and ambient gas (air), are bonded to the bonds that have become free through the breaking process. Thus, the residual proportion of fluorine atoms on the surface of the workpiece 9 is reduced to 60% or less compared to before contact (untreated), and the surface of the workpiece 9 is endowed with molecules containing any one or more of carbon atoms, hydrogen atoms, and oxygen atoms. By adjusting the input energy E, etc., the residual proportion of fluorine atoms can be reliably maintained within the preferred range.

[0069] As a result, by forming a hydrophilic layer on the surface of the treated object 9, the water contact angle of the treated object 9 is reduced, the wettability is improved, and the adhesion becomes good. That is, the treated object 9 undergoes surface modification.

[0070] Next, other embodiments of the present invention will be described. In the following embodiments, structures that are repeated in the already described embodiments will be labeled with the same reference numerals in the drawings and their descriptions will be omitted.

[0071] <Second Implementation Method>

[0072] Figure 2 This illustrates a second embodiment of the invention. The surface modification apparatus 1B in the second embodiment is an atmospheric pressure direct plasma treatment apparatus comprising a pair of electrodes: a long, flat hot electrode 21 and a roller-shaped (cylindrical) ground electrode 22B (hereinafter referred to as "roller electrode 22B"). A power supply 24 is connected to the hot electrode 21, and the roller electrode 22B is electrically grounded.

[0073] A plasma head 25, including a hot electrode 21 and a nozzle 14, is disposed below the roller electrode 22B. The roller electrode 22B and the hot electrode 21 are opposite each other across the electrode space 23. The length direction of the hot electrode 21 and the axis of the roller electrode 22B are oriented towards the processing width direction. Figure 2 (Orthogonal direction of the paper surface).

[0074] It should be noted that, in Figure 2 In the figure, the gap between electrodes 21 and 22B (the size of the space 23 between electrodes) is exaggerated.

[0075] Although the illustration is omitted, a solid dielectric layer is formed on the outer peripheral surface of the roller electrode 22B.

[0076] The plasma head 25 can also be configured on the upper side of the roller electrode 22B.

[0077] In the second embodiment, the workpiece 9B is a continuous film made of a difficult-to-bond material containing fluorine atoms, such as a PTFE film or an ETFE film. The workpiece 9B is wound approximately half a turn around the circumferential surface of the roller electrode 22B (the side opposite to the electrode 21). This allows the workpiece 9B to pass through the inter-electrode space 23.

[0078] The roller electrode 22B rotates about its own axis. This causes the workpiece 9B to be processed... Figure 2 The material is conveyed roughly to the right. The roller electrode 22B also serves as a support and moving mechanism for the workpiece 9B.

[0079] In parallel, a pulsed plasma close to atmospheric pressure is generated within the inter-electrode space 23 by applying a high-frequency pulsed voltage from power source 21. Furthermore, a process gas is activated by being supplied from nozzle 14 into the inter-electrode space 23. By bringing the plasma and the activated process gas into contact with the workpiece 9B, the workpiece 9B undergoes surface modification, and its adhesion is improved.

[0080] According to the apparatus 1B of the second embodiment, by conveying the film-like workpiece 9B in contact with the roller electrode 22B, damage to the workpiece 9B can be prevented. Furthermore, by designating the surface of the workpiece 9B to be processed as the surface side, plasma can be irradiated only on the desired surface for processing, while the undesired surface can remain unprocessed by contacting the roller electrode 22B on the back side. Moreover, by increasing the number of pairs of electrodes 21 and 22B, the processing area can be expanded. Therefore, quality and performance can be well maintained.

[0081] <Third Implementation Method>

[0082] Figure 3 This illustrates the third embodiment of the present invention.

[0083] The surface modification apparatus 1C of the third embodiment constitutes an atmospheric pressure remote plasma processing apparatus. In this specification, remote plasma processing refers to surface processing in which the workpiece to be processed is arranged separately from the inter-electrode space (plasma discharge space), so that the plasma exiting from the inter-electrode space comes into contact with the workpiece outside the inter-electrode space.

[0084] In detail, the surface modification apparatus 1C includes a plasma head 20C (plasma generation unit) and a stage 28. Inside the plasma head 20C, a pair of hot electrodes 21C and a ground electrode 22C are held in a left-right opposing manner. A power supply 24 is connected to the hot electrodes 21C. The ground electrode 22C is electrically grounded. Both electrodes 21C and 22C are formed in a flat plate shape, constituting parallel flat plate electrodes, but are not limited to this, they can also be coaxial cylindrical.

[0085] An inter-electrode space 23 is formed between a pair of opposing electrodes 21C and 22C. A gas supply path 13 is connected to the upper end of the inter-electrode space 23.

[0086] A nozzle 26, made of ceramic plate or the like, is provided at the lower end of the plasma head 20C. The lower end of the inter-electrode space 23 is connected to the nozzle 26.

[0087] A stage 28 is disposed below the plasma head 20C. The workpiece 9 is placed on the upper surface of the stage 28. The stage 28 is configured as a support portion that supports the workpiece in such a way that it comes into contact with the process gas passing through the inter-electrode space 23.

[0088] In the surface modification apparatus 1C, process gas from the process gas supply unit 10 is introduced into the inter-electrode space 23 and activated.

[0089] The activated process gas is blown downwards from nozzle 26 and comes into contact with the workpiece 9. This process modifies the surface of the workpiece 9.

[0090] Furthermore, by moving the plasma head 20C relative to the stage 28, the entire area of ​​the object to be processed 9 is processed.

[0091] The stage 28 can also move relative to the plasma head 20C.

[0092] This invention is not limited to the described embodiments, and various modifications can be made without departing from its spirit.

[0093] For example, glow discharge is preferred for forming plasma, but corona discharge, streamer discharge, arc discharge, and various other discharge methods are also acceptable. Furthermore, an electrode shape with a dielectric barrier between the discharge electrodes is preferred.

[0094] Plasma is not limited to being formed by discharges at near atmospheric pressure; it can also be formed by discharges in a vacuum.

[0095] Example 1

[0096] Next, embodiments will be described. The present invention is not limited to the following embodiments.

[0097] In Example 1, an atmospheric pressure direct plasma device comprising parallel flat plate electrodes was prepared.

[0098] The non-adhesive material of the treated object is a film-like PTFE. The atomic composition of the surface of the blank (untreated) treated object is 67.6 atom% fluorine (F) and 32.4 atom% carbon (C).

[0099] The object to be processed is placed on the ground electrode 22 on the lower side of a pair of electrodes forming parallel flat plate electrodes, so that it is opposite to the hot electrode 21 on the upper side.

[0100] Nitrogen (N2) is used as the process gas, and carbon monoxide (CO) is added as an additive. The addition rate of carbon monoxide is 5 L / min.

[0101] The total flow rate of the process gas is 50 L / min.

[0102] The process gas is supplied to the space between the electrodes, and a pulsed high-frequency electric field is applied between the electrodes to generate atmospheric pressure pulsed plasma. This plasma is then irradiated onto the workpiece. Furthermore, the plasma-activated process gas comes into contact with the workpiece.

[0103] The energy input per unit area is adjusted by changing the DC power before high-frequency conversion in power supply 24. The energy input per unit area when the peel strength reaches its maximum, as described later, is E = 11.3 J / cm². 2 .

[0104] The peak-to-peak voltage of the pulsed applied voltage is 17 kVpp, and the frequency is 50 kHz.

[0105] After treatment, the atomic composition of the treated surface was analyzed by X-ray photoelectron spectroscopy (XPS). The analytical apparatus used was a PHI5000 Versa Probe II spectrometer manufactured by ULVAC-PHI Corporation.

[0106] As shown in Table 1, the analytical results are 5.5 atom% fluorine (F), 45.3 atom% carbon (C), 28.9 atom% nitrogen (N), and 20.2 atom% oxygen (O).

[0107] Therefore, the proportion of fluorine atoms remaining on the surface of the treated object relative to that before treatment is (5.5 / 67.6) = 8.2%.

[0108] It is believed that the nitrogen (N) in the surface atomic composition originates from the carrier gas and nitrogen molecules (N2) in the air.

[0109] Furthermore, hydrogen (H) cannot be detected in XPS, but hydrophilicity increases after treatment. Therefore, it is speculated that hydrogen-containing groups such as OH, NH, and CH from water vapor (H2O) in the air are imparted to the surface of the treated object.

[0110] In fact, infrared light analysis of the treated object yields results such as... Figure 5 As shown in (a), groups containing hydrogen atoms such as OH and NH were identified.

[0111] As an infrared spectrophotometer, the Nicolet iN10MX manufactured by Thermo Scientific was used.

[0112] As an evaluation, two membrane pieces were cut from the treated material, and after these membrane pieces were bonded together, the peel strength was determined by a peel test.

[0113] Acrylic adhesives are used as the bonding agent (adhesive).

[0114] The peel test was a T-type peel test according to JIS K 6854-3.

[0115] Regarding peel strength based on the peel test, the untreated state is set to 1; a peel strength of 2.5 times or more is set to excellent (◎); a peel strength of more than 1.5 times but less than 2.5 times is set to good (○); and a peel strength of less than 1.5 times is set to poor (×). A three-stage evaluation is conducted (refer to...). Figure 4 As a result, the peel strength was excellent (◎).

[0116] Example 2

[0117] In Example 2, carbon dioxide (CO2) was used as an additive component of the process gas.

[0118] The addition rate is 10 L / min.

[0119] The energy input per unit area when the peel strength reaches its maximum, as described later, is E = 32.3 J / cm². 2 .

[0120] Except for the processing conditions, post-processing analysis and evaluation, the process is the same as in Example 1.

[0121] As shown in Table 1, according to XPS analysis, the atomic composition of the surface of the treated object is 38.3 atom% fluorine (F), 43.6 atom% carbon (C), 9.9 atom% nitrogen (N), and 8.2 atom% oxygen (O).

[0122] Therefore, the proportion of fluorine atoms remaining on the surface of the treated object relative to that before treatment is (38.3 / 67.6) = 57.4%.

[0123] Furthermore, the increased hydrophilicity after treatment suggests that hydrogen-containing groups such as OH, NH, and CH were imparted to the surface of the treated material.

[0124] The peel strength in the peel test was good (○).

[0125] [Table 1]

[0126] Discharge method - Dielectric barrier discharge Dielectric barrier discharge Difficult-to-bond materials PTFE PTFE PTFE carrier gas - N2 N2 Total flow - 50L / min 50L / min Additives - carbon monoxide carbon dioxide Added amount - 5L / min 10L / min <![CDATA[E[J / cm 2 ]]]> - 11.3 32.3 F[atom%] 67.6 5.5 38.3 C[atom%] 32.4 45.3 43.6 N[atom%] - 28.9 9.9 O[atom%] - 20.2 8.2 F Residual Percentage [%) - 8.2 57.4 Peel strength × ◎ O

[0127] [Comparative Example 1]

[0128] As a comparative example 1, the process gas was set to 100% nitrogen (N2). That is, no components were added.

[0129] The flow rate of the process gas (N2) is 50 L / min.

[0130] The energy input per unit area when the peel strength reaches its maximum, as described later, is E = 10.35 J / cm². 2 .

[0131] Except for the processing conditions, post-processing analysis and evaluation, the process is the same as in Example 1.

[0132] As shown in Table 2, according to XPS analysis, the atomic composition of the surface of the treated object is 61 atom% fluorine (F), 35.1 atom% carbon (C), 2.4 atom% nitrogen (N), and 1.5 atom% oxygen (O).

[0133] Therefore, the proportion of fluorine atoms remaining on the surface of the treated object relative to that before treatment is (61 / 67.6) = 91.5%.

[0134] The peel strength in the peel test was poor (×).

[0135] [Comparative Example 2]

[0136] In Comparative Example 2, oxygen (O2) was used as an additive component of the process gas.

[0137] The addition rate is 0.05 L / min.

[0138] The energy input per unit area when the peel strength reaches its maximum, as described later, is E = 10.35 J / cm². 2 .

[0139] Except for the processing conditions, post-processing analysis and evaluation, the process is the same as in Example 1.

[0140] As shown in Table 2, according to XPS analysis, the atomic composition of the surface of the treated object is 60.3 atom% fluorine (F), 36.1 atom% carbon (C), 2.4 atom% nitrogen (N), and 1.2 atom% oxygen (O).

[0141] Therefore, the proportion of fluorine atoms remaining on the surface of the treated object relative to that before treatment is (60.3 / 67.6) = 90.4%.

[0142] The peel strength in the peel test was poor (×).

[0143] [Table 2]

[0144] Discharge method Dielectric barrier discharge Dielectric barrier discharge Difficult-to-bond materials PTFE PTFE carrier gas N2 N2 Total flow 50L / min 50L / min Additives - oxygen Added amount - 0.05L / min <![CDATA[E[J / cm 2 ]]]> 10.35 10.35 F[atom%] 61 60.3 C[atom%] 35.1 36.1 N[atom%] 2.4 2.4 O[atom%] 1.5 1.2 F Residual Percentage [%) 91.5 90.4 Peel strength × ×

[0145] Example 3

[0146] In Example 3, hydrogen (H2) was used as an additive component of the process gas.

[0147] The addition rate is 2L / min.

[0148] The energy input per unit area when the peel strength reaches its maximum, as described later, is E = 56.3 J / cm². 2 .

[0149] Except for the processing conditions, post-processing analysis and evaluation, the process is the same as in Example 1.

[0150] As shown in Table 3, according to XPS analysis, the atomic composition of the surface of the treated object is 37.3 atom% fluorine (F), 50.9 atom% carbon (C), 6.5 atom% nitrogen (N), and 5.4 atom% oxygen (O).

[0151] Therefore, the proportion of fluorine atoms remaining on the surface of the treated object relative to that before treatment is (37.3 / 67.6) = 55.9%.

[0152] It is believed that the oxygen (O) in the surface atomic composition originates from oxygen molecules (O2) and carbon dioxide (CO2) in the air, which serves as the ambient gas. It is also believed that the nitrogen (N) originates from the carrier gas and nitrogen molecules (N2) in the air.

[0153] Furthermore, while hydrogen (H) could not be detected by XPS, hydrophilicity increased after treatment, suggesting that hydrogen-containing groups such as OH, NH, and CH were imparted to the surface of the treated material.

[0154] The peel strength in the peel test was excellent (◎).

[0155] Example 4

[0156] In Example 4, water vapor (H2O) was used as an additive component of the process gas.

[0157] The addition amount was 2.17 g / min.

[0158] The energy input per unit area when the peel strength reaches its maximum, as described later, is E = 7 J / cm². 2 .

[0159] Except for the processing conditions, post-processing analysis and evaluation, the process is the same as in Example 1.

[0160] As shown in Table 3, according to XPS analysis, the atomic composition of the surface of the treated object is 28.3 atom% fluorine (F), 55.6 atom% carbon (C), 9.6 atom% nitrogen (N), and 6.5 atom% oxygen (O).

[0161] Therefore, the proportion of fluorine atoms remaining on the surface of the treated object relative to that before treatment is (28.3 / 67.6) = 42.4%.

[0162] Furthermore, the increased hydrophilicity after treatment suggests that hydrogen-containing groups such as OH, NH, and CH were imparted to the surface of the treated material.

[0163] The peel strength in the peel test was good (○).

[0164] Example 5

[0165] In Example 5, ethanol (C2H5OH) was used as an additive component of the process gas.

[0166] The addition rate is 5.5 g / min.

[0167] The energy input per unit area when the peel strength reaches its maximum, as described later, is E = 11.3 J / cm². 2 .

[0168] Except for the processing conditions, post-processing analysis and evaluation, the process is the same as in Example 1.

[0169] As shown in Table 3, according to XPS analysis, the atomic composition of the surface of the treated object is 5 atom% fluorine (F), 56.1 atom% carbon (C), 19.4 atom% nitrogen (N), and 19.5 atom% oxygen (O).

[0170] Therefore, the proportion of fluorine atoms remaining on the surface of the treated object relative to that before treatment is (5 / 67.6) = 7.5%.

[0171] Furthermore, the increased hydrophilicity after treatment suggests that hydrogen-containing groups such as OH, NH, and CH were imparted to the surface of the treated material.

[0172] like Figure 5 As shown in (b), infrared analysis confirmed the presence of hydrogen-containing groups such as OH, NH, and CH.

[0173] The peel strength in the peel test was excellent (◎).

[0174] [Table 3]

[0175] Discharge method Dielectric barrier discharge Dielectric barrier discharge Dielectric barrier discharge Difficult-to-bond materials PTFE PTFE PTFE carrier gas N2 N2 N2 Total flow 50L / min 50L / min 50L / min Additives hydrogen water vapor ethanol Added amount 2L / min 2.17 g / min 5.5g / min <![CDATA[E[J / cm 2 ]]]> 56.3 7 11.3 F[atom%] 37.3 28.3 5 C[atom%] 50.9 55.6 56.1 N[atom%] 6.5 9.6 19.4 O[atom%] 5.4 6.5 19.5 F Residual Percentage [%) 55.9 42.4 7.5 Peel strength ◎ ○ ◎

[0176] Figure 4 This represents the energy input per unit area for each added component (J / cm²). 2 The relationship between peel strength and peel strength.

[0177] If the energy input per unit area is E = 0.9 J / cm² 2 ~135.0 J / cm 2 Therefore, it can be said that the peel strength is improved, and the surface modification effect is achieved.

[0178] Example 6

[0179] In Example 6, propanol (C3H7OH) was used as an additive component of the process gas.

[0180] The addition rate is 2.5 g / min.

[0181] The energy input per unit area when the peel strength reaches its maximum, as described later, is E = 5.11 J / cm². 2 .

[0182] Except for the processing conditions, post-processing analysis and evaluation, the process is the same as in Example 1.

[0183] As shown in Table 4, according to XPS analysis, the atomic composition of the surface of the treated object is 14 atom% fluorine (F), 54 atom% carbon (C), 16.5 atom% nitrogen (N), and 15.5 atom% oxygen (O).

[0184] Therefore, the proportion of fluorine atoms remaining on the surface of the treated object relative to that before treatment is (14 / 67.6) = 21%.

[0185] Furthermore, the increased hydrophilicity after treatment suggests that hydrogen-containing groups such as OH, NH, and CH were imparted to the surface of the treated material.

[0186] The peel strength in the peel test was excellent (◎).

[0187] Example 7

[0188] In Example 7, hexanol (CH3(CH2)5OH) was used as an additive component of the process gas.

[0189] The addition rate is 0.3 g / min.

[0190] The energy input per unit area when the peel strength reaches its maximum, as described later, is E = 5.11 J / cm². 2 .

[0191] Except for the processing conditions, post-processing analysis and evaluation, the process is the same as in Example 1.

[0192] As shown in Table 4, according to XPS analysis, the atomic composition of the surface of the treated object is 16 atom% fluorine (F), 56.3 atom% carbon (C), 13.6 atom% nitrogen (N), and 14.1 atom% oxygen (O).

[0193] Therefore, the proportion of fluorine atoms remaining on the surface of the treated object relative to that before treatment is (16 / 67.6) = 24.0%.

[0194] Furthermore, the increased hydrophilicity after treatment suggests that hydrogen-containing groups such as OH, NH, and CH were imparted to the surface of the treated material.

[0195] The peel strength in the peel test was good (○).

[0196] Example 8

[0197] In Example 8, ethylene glycol (C2H6O2) was used as an additive component of the process gas.

[0198] The dosage is 6 mg / min.

[0199] The energy input per unit area when the peel strength reaches its maximum, as described later, is E = 5.11 J / cm². 2 .

[0200] Except for the processing conditions, post-processing analysis and evaluation, the process is the same as in Example 1.

[0201] As shown in Table 4, according to XPS analysis, the atomic composition of the surface of the treated object is 20 atom% fluorine (F), 55.9 atom% carbon (C), 12.3 atom% nitrogen (N), and 11.8 atom% oxygen (O).

[0202] Therefore, the proportion of fluorine atoms remaining on the surface of the treated object relative to that before treatment is (20 / 67.6) = 30.0%.

[0203] Furthermore, the increased hydrophilicity after treatment suggests that hydrogen-containing groups such as OH, NH, and CH were imparted to the surface of the treated material.

[0204] The peel strength in the peel test was good (○).

[0205] Example 9

[0206] In Example 9, ammonia (NH3) was used as an additive component of the process gas.

[0207] The addition amount was 2.17 g / min.

[0208] The energy input per unit area when the peel strength reaches its maximum, as described later, is E = 2.05 J / cm². 2 .

[0209] Except for the processing conditions, post-processing analysis and evaluation, the process is the same as in Example 1.

[0210] As shown in Table 4, according to XPS analysis, the atomic composition of the surface of the treated object is 33.3 atom% fluorine (F), 52.3 atom% carbon (C), 7 atom% nitrogen (N), and 7.4 atom% oxygen (O).

[0211] Therefore, the proportion of fluorine atoms remaining on the surface of the treated object relative to that before treatment is (33.3 / 67.6) = 49.9%.

[0212] Furthermore, the increased hydrophilicity after treatment suggests that hydrogen-containing groups such as OH, NH, and CH were imparted to the surface of the treated material.

[0213] The peel strength in the peel test was good (○).

[0214] [Table 4]

[0215]

[0216] Example 10

[0217] In Example 10, a corona discharge device comprising parallel plate electrodes was prepared.

[0218] The difficult-to-bond material of the treated object is a film-like PTFE.

[0219] The object to be processed is placed on the lower ground electrode of a pair of electrodes forming parallel flat plates, so that it is opposite to the upper hot electrode.

[0220] The process gas is ethanol. The addition rate is set at 5.5 g / min.

[0221] The process gas carrier gas is nitrogen (N2), and the total flow rate of the process gas is 50 L / min.

[0222] The process gas is supplied to the space between the electrodes, and a corona discharge is generated between the electrodes at atmospheric pressure, directly irradiating the surface of the workpiece with the corona discharge. Furthermore, the process gas activated by the corona discharge is brought into contact with the workpiece.

[0223] The energy input per unit area when the peel strength reaches its maximum, as described later, is E = 4.94 J / cm². 2 .

[0224] After treatment, the atomic composition of the surface of the treated object was measured, the proportion of residual fluorine atoms was calculated, and the peel strength was evaluated in the same manner as in Example 1.

[0225] As shown in Table 5, according to XPS analysis, the atomic composition of the surface of the treated object is 26 atom% fluorine (F), 49.3 atom% carbon (C), 12.1 atom% nitrogen (N), and 12.6 atom% oxygen (O).

[0226] Therefore, the proportion of fluorine atoms remaining on the surface of the treated object relative to that before treatment is (26 / 67.6) = 38.5%.

[0227] Furthermore, the increased hydrophilicity after treatment suggests that hydrogen-containing groups such as OH, NH, and CH were imparted to the surface of the treated material.

[0228] The peel strength in the peel test was good (○).

[0229] [Comparative Example 3]

[0230] As a comparative example, a process gas with 20 vol% air added to the carrier gas (N2) and a total flow rate of 50 L / min was used to perform the same corona treatment as in Example 10.

[0231] The energy input per unit area when the peel strength reaches its maximum, as described later, is E = 4.94 J / cm². 2 .

[0232] As shown in Table 5, according to XPS analysis, the atomic composition of the surface of the treated object is 63.6 atom% fluorine (F), 32.6 atom% carbon (C), 2.6 atom% nitrogen (N), and 1.2 atom% oxygen (O).

[0233] Therefore, the proportion of fluorine atoms remaining on the surface of the treated object relative to that before treatment is (63.6 / 67.6) = 94.1%.

[0234] The peel strength in the peel test was poor (×).

[0235] Example 11

[0236] In Example 11, a film-like ETFE was used as a difficult-to-bond material for the treated object. The atomic composition of the surface of the blank (untreated) ETFE was 48.9 atom% fluorine (F) and 51.1 atom% carbon (C).

[0237] The processing apparatus used is the same plasma processing apparatus as in Example 1.

[0238] The process gas was added as ethanol (C2H5OH) at a rate of 2.17 g / min.

[0239] The process gas carrier gas is nitrogen (N2), and the total flow rate of the process gas is 50 L / min.

[0240] The process gas is supplied to the space between the electrodes, generating atmospheric pressure plasma between them, which directly irradiates the surface of the workpiece. Furthermore, the plasma-activated process gas comes into contact with the workpiece.

[0241] The energy input per unit area is E = 32.3 J / cm². 2 .

[0242] After treatment, the atomic composition of the surface of the treated object was determined, the proportion of residual fluorine atoms was calculated, and the peel strength was evaluated in the same manner as in Example 1.

[0243] As shown in Table 5, according to XPS analysis, the atomic composition of the surface of the treated object is 4.9 atom% fluorine (F), 67 atom% carbon (C), 16.6 atom% nitrogen (N), and 11.5 atom% oxygen (O).

[0244] Therefore, the proportion of fluorine atoms remaining on the surface of the treated object relative to that before treatment is (4.9 / 48.9) = 10.0%.

[0245] Furthermore, the increased hydrophilicity after treatment suggests that hydrogen-containing groups such as OH, NH, and CH were imparted to the surface of the treated material.

[0246] The peel strength in the peel test was excellent (◎).

[0247] [Table 5]

[0248] Discharge method Corona discharge Corona discharge Dielectric barrier discharge - Difficult-to-bond materials PTFE PTFE ETFE ETFE carrier gas N2 N2 N2 - Total flow 50L / min 50L / min 50L / min - Additives ethanol Air ethanol - Added amount 5.5g / min 20 vol% 2.17 g / min - <![CDATA[E[J / cm 2 ]]]> 4.94 4.94 32.3 - F[atom%] 26 63.6 4.9 48.9 C[atom%] 49.3 32.6 67 51.1 N[atom%] 12.1 2.6 16.6 - O[atom%] 12.6 1.2 11.5 - F Residual Percentage [%) 38.5 94.1 10.0 - Peel strength ○ × ◎ ×

[0249] As demonstrated by the above embodiments, according to the method of the present invention, a good surface modification effect can be obtained by setting the conditions such that the residual proportion of fluorine atoms on the surface of the treated object is about 60% or less. It has been determined that, depending on the added components of the process gas, a better surface modification effect can be obtained by setting the conditions such that the residual proportion is preferably about 20% or less, and more preferably about 10% or less.

[0250] Industrial applicability

[0251] This invention can be applied to improve the wettability of fluorinated, difficult-to-bond materials such as PTFE and ETFE.

[0252] Symbol Explanation

[0253] 1 Surface modification device

[0254] 1B, 1C Surface Modification Devices

[0255] 9.9B Difficult-to-bond resin film (substance to be treated)

[0256] 10 Process Gas Generation Section

[0257] 13 Gas Supply Path

[0258] 14 Nozzles

[0259] 20 Plasma Generation Unit

[0260] 20C Plasma Head (Plasma Generation Unit)

[0261] 21b Solid dielectric layer

[0262] 22b Solid dielectric layer

[0263] 21°C Thermoelectric electrode (electrode)

[0264] 22 Grounding electrode (electrode, support)

[0265] 22B Roller Electrode (Electrode, Support)

[0266] 22C Grounding Electrode (Electrode)

[0267] 23. Interelectrode space (plasma discharge space)

[0268] 24 Power Supply

[0269] 25 Plasma Head

[0270] 27. Mobile mechanism

[0271] 28. Workbench (Support Section)

Claims

1. A surface modification method for modifying the surface of a workpiece made of a difficult-to-bond material containing fluorine atoms, wherein, The surface modification method includes: The plasma process activates a process gas containing one or more of the following as additives: carbon monoxide, carbon dioxide, ethanol, propanol, hexanol, ethylene glycol, and ammonia, through plasma, thereby bringing it into contact with the object being treated. and The modification process, through a reaction based on the contact, reduces the residual proportion of fluorine atoms on the surface of the workpiece to less than 60% of that before the contact, and imparts to the surface of the workpiece any one of carbon atoms, hydrogen atoms, and oxygen atoms, or molecules containing one or more of them. The plasma process includes: a generating step of generating 1.013 x 10 4 Pa~50.663 x 10 4 plasma discharge in the range of 1.013 x 10 The supply process supplies the process gas to the space between the electrodes; and The contact process involves bringing the process gas, either within or passing through the inter-electrode space, into contact with the workpiece. The input energy in the plasma process is 0.9 J / cm 2 ~135.0 J / cm 2 wherein, in the case where the additive ingredient is carbon monoxide, carbon dioxide, ethanol, propanol, hexanol, ethylene glycol, ammonia, the input energy is 5 J / cm 2 ~60 J / cm 2 .

2. The surface modification method according to claim 1, wherein, The plasma process includes the process of the object being processed passing through the space between the electrodes.

3. The surface modification method according to claim 1 or 2, wherein, The peak-to-peak voltage of the voltage applied between the pair of electrodes is 3kVpp~25kVpp, and the frequency is 10kHz~70kHz.

4. The surface modification method according to claim 1 or 2, wherein, The material being treated is in the form of a film. The pair of electrodes includes a roller-shaped ground electrode and a hot electrode disposed opposite to the ground electrode. In the plasma process, the object to be treated is transported in contact with the ground electrode, and the plasma is generated in the range of 1.013 x 10 4 Pa~50.663 x 10 4 Pa range.

5. The surface modification method according to claim 1 or 2, wherein, The plasma process involves applying a pulsed voltage between the pair of electrodes to generate a 1.013 × 10⁻⁶ ohmmeter in the space between the electrodes. 4 Pa ~ 50.663 × 10 4 The process of pulsed plasma in the Pa range.

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