Methods for manufacturing surface-modified tetrafluoroethylene-based polymers, methods for manufacturing modified powders, liquid compositions, methods for manufacturing modified molded articles, and modified molded articles.

Abstract

This invention provides a method for manufacturing modified tetrafluoroethylene polymers and powders by modifying tetrafluoroethylene polymers and powders thereof, and a method for manufacturing modified molded articles of tetrafluoroethylene polymers with highly surface-modified surfaces. The method for manufacturing modified tetrafluoroethylene polymers and powders of this invention involves plasma treatment of the tetrafluoroethylene polymer and the powder of the polymer under an atmosphere close to atmospheric pressure to obtain surface-modified tetrafluoroethylene polymers. The method for manufacturing molded articles of this invention involves plasma treatment of the surface layer of a molded article having a surface layer containing tetrafluoroethylene polymers at least a portion of it under an atmosphere close to atmospheric pressure containing a reducing gas having hydrogen atoms, thereby manufacturing a molded article having a modified layer formed by introducing hydrogen atoms into the tetrafluoroethylene polymer at least a portion of its surface.

Description

[Technical Field]

[0001] This invention relates to a method for manufacturing a surface-modified tetrafluoroethylene polymer, a method for manufacturing modified powder, a liquid composition, a method for manufacturing modified molded articles, and modified molded articles. [Previous Technology]

[0002] Tetrafluoroethylene polymers possess excellent physical properties such as release properties, electrical insulation, water and oil repellency, chemical resistance, weather resistance, and heat resistance. Liquid compositions containing their powders are useful as materials that can be easily formed into various molded articles (Patent Document 1). However, due to their extremely low polarity, tetrafluoroethylene polymers lack interaction with other compounds, such as liquid dispersion media, resulting in insufficient powder dispersibility. Therefore, in order to improve powder dispersibility and adjust the liquid properties of the liquid composition, surfactants, thickeners, and other modifiers are often added.

[0003] Furthermore, films made of tetrafluoroethylene-based polymers possess excellent physical properties such as electrical insulation, water and oil repellency, chemical resistance, and heat resistance, making them useful as printed circuit board materials (Patent Document 2). However, the adhesion of tetrafluoroethylene-based polymer films is not yet sufficient. Therefore, in order to improve surface properties such as adhesion, research is underway to modify the surface of the film. Patent Document 3 describes a method in which a polytetrafluoroethylene film is plasma-treated in an atmosphere containing rare gases at near atmospheric pressure, thereby introducing peroxide functional groups onto the surface of the film.

[0004] Furthermore, tetrafluoroethylene-based polymers are low-polarity polymers with excellent insulation resistance or insulation destructive properties, and the surface of their molded products is difficult to modify easily. Also, the understanding of the behavior of tetrafluoroethylene-based polymers when provided with plasma treatment is insufficient, and there are situations where their effects are difficult to stabilize and maintain.

[0005] Therefore, the current practice is to combine other methods when plasma treating molded products of tetrafluoroethylene-based polymers. For example, in Patent Document 3, a polytetrafluoroethylene film is plasma treated to introduce peroxide functional groups onto its surface, then immersed in water to introduce hydroxyl groups onto its surface, and finally, a silane coupling agent is used to modify the surface of the film. (Prior Art Documents, Patent Documents)

[0006] Patent Document 1: International Publication No. 2016 / 159102; Patent Document 2: International Publication No. 2019 / 142790; Patent Document 3: Japanese Patent Application Publication No. 2013-049819 [Summary of the Invention]

[0007] [The problem the invention aims to solve]

[0008] The inventors have studied a plasma treatment method for highly modifying the surface of tetrafluoroethylene-based polymer powder. The results showed that when the surface of tetrafluoroethylene-based polymer powder is treated under specific plasma treatment conditions, its surface is modified, and its surface properties, such as wettability, and the dispersibility of the liquid composition prepared therefrom are improved without compromising its physical properties.

[0009] Furthermore, when performing plasma treatment on molded articles of tetrafluoroethylene-based polymers, the inventors investigated plasma treatment conditions that could highly modify the surface of the molded articles of tetrafluoroethylene-based polymers without requiring the combination described in Patent Document 3. It was found that if the molded article was treated under specific plasma treatment conditions, a stable layer would be formed. Furthermore, it was found that by forming this layer, the wettability of the molded article and surface properties such as adhesion were improved without compromising the overall properties of the tetrafluoroethylene-based polymer.

[0010] The object of this invention is to provide a method for highly modifying tetrafluoroethylene-based polymers to improve their physical properties. The object of this invention is to provide a method for highly surface-modifying tetrafluoroethylene-based polymer powder to improve its surface properties, and a liquid composition prepared therefrom with excellent dispersibility and other liquid properties. The object of this invention is to provide a method for highly surface-modifying molded articles of tetrafluoroethylene-based polymers to improve their surface properties, and a molded article of a highly surface-modified tetrafluoroethylene-based polymer. [Technical Means for Solving the Problem]

[0011] The present invention has the following forms. <1> A method for manufacturing a modified tetrafluoroethylene polymer, wherein the tetrafluoroethylene polymer is subjected to plasma treatment in an atmosphere close to atmospheric pressure to obtain a surface-modified tetrafluoroethylene polymer. <2> A method for manufacturing a modified powder, wherein the powder of a tetrafluoroethylene polymer is subjected to plasma treatment in an atmosphere close to atmospheric pressure to modify the surface of the powder. <3> The manufacturing method of <2> above, wherein the powder is subjected to plasma treatment in an atmosphere close to atmospheric pressure containing a reducing gas having hydrogen atoms to obtain a powder formed by introducing hydrogen atoms into the tetrafluoroethylene polymer. <4> The manufacturing method of <2> or <3> above, wherein the plasma treatment is performed in an atmosphere that blocks air. <5> The manufacturing methods of <2> to <4> above, wherein the powder is subjected to plasma treatment in an atmosphere containing a rare gas before performing the plasma treatment. <6> The manufacturing method of <2> to <5> above, wherein the atmosphere comprises at least one of a reducing gas having hydrogen atoms, a vinyl compound, and a vinylidene compound. <7> The manufacturing method of <2> to <6> above, wherein the atmosphere further comprises a rare gas. <8> The manufacturing method of <2> to <7> above, wherein the pressure close to atmospheric pressure is 0.08 to 0.12 MPa. <9> The manufacturing method of <2> to <8> above, wherein the average particle size of the powder is 50 μm or less. <10> The manufacturing method of <2> to <9> above, wherein the tetrafluoroethylene polymer is a tetrafluoroethylene polymer with a fluorine content of 70 to 76% by mass. <11> The manufacturing method of <2> to <10> above, wherein the tetrafluoroethylene polymer has atomic groups containing oxygen atoms. <12> A liquid composition comprising a modified powder obtained by any one of the manufacturing methods described in <2> to <11> above, and a liquid dispersion medium, wherein the modified powder is dispersed. <13> The liquid composition of <12> above, wherein the average particle size of the modified powder is 50 μm or less. <14> The liquid composition of <12> or <13>, wherein the tetrafluoroethylene polymer is a tetrafluoroethylene polymer with a fluorine content of 70 to 76% by mass. <15> The liquid composition of <12> to <14> above, wherein the tetrafluoroethylene polymer has atomic groups containing oxygen atoms. <16> A method for manufacturing a molded article, wherein plasma treatment is performed on the surface layer of a molded article having at least a portion of a surface layer comprising a tetrafluoroethylene-based polymer in an atmosphere containing a reducing gas having hydrogen atoms at near atmospheric pressure, thereby manufacturing a molded article having a modified layer formed by introducing hydrogen atoms into the tetrafluoroethylene-based polymer on at least a portion of the surface. <17> The manufacturing method of <16> above, wherein the plasma treatment is performed in an atmosphere that blocks air.<18> In the manufacturing method of <16> or <17> above, the surface layer is pre-treated with plasma in an atmosphere free of reducing gases before performing the plasma treatment. <19> In the manufacturing method of <16> to <18> above, the reducing gas system is hydrogen, ammonia, or hydrocarbon gas. <20> In the manufacturing method of <16> to <19> above, the atmosphere for the plasma treatment further includes nitrogen or a rare gas. <21> In the manufacturing method of <16> to <20> above, the pressure close to atmospheric pressure is 0.08 to 0.12 MPa. <22> In the manufacturing method of <16> to <21> above, the molded product having at least a portion of a surface layer containing a tetrafluoroethylene-based polymer is a tetrafluoroethylene-based polymer film, or a laminate having a substrate layer and a tetrafluoroethylene-based polymer layer. <23> The manufacturing method of <16> to <22> above, wherein the fluorine content of the aforementioned tetrafluoroethylene polymer is 70 to 76% by mass. <24> The manufacturing method of <16> to <23> above, wherein the aforementioned tetrafluoroethylene polymer has atomic groups containing oxygen atoms. <25> A molded article comprising a tetrafluoroethylene polymer, and having a modified layer formed by introducing hydrogen atoms into the tetrafluoroethylene polymer on at least a portion of its surface, wherein the maximum height of the peak at 284 eV to 286 eV in the region from the surface to a depth of 1 nm, as measured by X-ray photoelectron spectroscopy, is at least 0.2 times higher than the maximum height of the peak at 289 eV to 295 eV in the same region, and the fluorine atom content in the same region is 55% or less. <26> The molded article of <25> above, wherein the fluorine content of the aforementioned tetrafluoroethylene polymer is 70 to 76% by mass. <27> As described in <25> or <26> above, the tetrafluoroethylene polymer has atomic groups containing oxygen atoms. <28> As described in <25> to <27> above, the thickness of the modified layer is less than 1000 nm. <29> As described in <25> to <27> above, the molded article is a film of tetrafluoroethylene polymer, or a laminate having a substrate layer and a tetrafluoroethylene polymer layer. [Effects of the Invention].

[0012] According to the present invention, highly modified tetrafluoroethylene-based polymers can be manufactured. According to the present invention, a modified powder of a tetrafluoroethylene-based polymer can be manufactured, which does not impair the physical properties of the tetrafluoroethylene-based polymer and exhibits excellent wettability and dispersibility; and a liquid composition with excellent liquid properties can be easily manufactured from this powder. From this liquid composition, molded articles (layered articles, single films, etc.) possessing the physical properties of tetrafluoroethylene-based polymers and exhibiting excellent adhesion can be easily manufactured. According to the present invention, a molded article of a tetrafluoroethylene-based polymer can be manufactured, having at least a portion of its surface a stable modified layer formed by efficiently introducing hydrogen atoms into the tetrafluoroethylene-based polymer. Furthermore, a molded article of a tetrafluoroethylene-based polymer can be obtained, possessing the overall physical properties of the tetrafluoroethylene-based polymer of the molded article, and with improved surface properties such as adhesion.

Implementation Method

[0013] The following terms have the following meanings: "Tetrafluoroethylene-based polymer" refers to a polymer containing units based on tetrafluoroethylene (hereinafter also referred to as "TFE units"). "Glass transition point (Tg) of the polymer" refers to the value obtained by analyzing the polymer using dynamic viscoelasticity determination (DMA). "Melting temperature (melting point) of the polymer" refers to the temperature corresponding to the maximum value of the melting peak measured using differential scanning calorimetry (DSC). "(Meth)acrylate" refers to the general term for acrylates and methacrylates. "D50" is the average particle size of the powder, which is the cumulative 50% diameter of the powder volume as determined by laser diffraction-scattering. That is, it is the particle size at the point where the cumulative volume of the powder reaches 50% by measuring the particle size distribution of the powder using laser diffraction-scattering, setting the total volume of the powder cluster to 100%, and obtaining a cumulative curve on the cumulative curve. "D90" refers to the cumulative volumetric particle size of the powder, which is calculated as the cumulative 90% diameter of the powder's volume. The term "monomer-based unit" refers to a group of atoms based on the aforementioned monomer, formed through the polymerization of the monomer. The unit can be formed directly through a polymerization reaction, or it can be formed by processing the polymer to convert a portion of the aforementioned unit into other structures. Hereinafter, units based on monomer a will also be referred to as "monomer a units."

[0014] The manufacturing method of the present invention (hereinafter also referred to as "the method") is a method for manufacturing modified F polymer, which involves plasma treatment of tetrafluoroethylene polymer (hereinafter also referred to as "F polymer") in an atmosphere close to atmospheric pressure to obtain modified F polymer.

[0015] The first aspect of this method (hereinafter also referred to as Method 1) is a method for manufacturing modified powder, wherein the F polymer powder (hereinafter also referred to as the original powder) is subjected to plasma treatment in an atmosphere close to atmospheric pressure, thereby modifying the surface of the powder.

[0016] The modified powder is preferably a modified layer formed by modifying the surface with F polymer. More preferably, the modified layer is a modified layer formed by introducing hydrogen atoms into the F polymer, or a modified layer formed by introducing a polymer of vinyl compounds or vinylidene compounds into the F polymer.

[0017] The maximum height of the peak (hereinafter referred to as "peak H") located at 284 eV to 286 eV in the region from the surface to a depth of 1 nm in the modified layer formed by introducing hydrogen atoms into polymer F, as measured by X-ray photoelectron spectroscopy (hereinafter also referred to as "ESCA"), is preferably 0.2 times or more, more preferably 1 times, relative to the maximum height of the peak (hereinafter referred to as "peak F") located at 289 eV to 295 eV in the same region.

[0018] The surface measurements performed using ESCA were performed using a Quantera II (manufactured by ULVAC-PHI). The X-ray source was a 100 W monochromatic AlKα beam, and an ion gun and a neutralization gun using a barium oxide emitter were employed to prevent the sample surface from becoming charged. The photoelectron detection area was 100 μm, the photoelectron detection angle was 45 degrees, and the transmission energy was 55 eV. Furthermore, the fluorine atom content ratio was calculated by measuring the intensity of various detected peaks (N1s, O1s, C1s, and F1s orbitals). The depth from the surface was determined based on the sputtering rate of the SiO2 sputtered film using C60 ions as the sputtering ions.

[0019] Peaks H and F are, respectively, photoelectron peaks based on the 1s orbital of carbon atoms (C1s) and photoelectron peaks based on the 1s orbital of fluorine atoms (F1s). In other words, peak H can be regarded as a peak originating from the single bond (CH bond) between carbon and hydrogen atoms, and peak F can be regarded as a peak originating from the single bond (CF bond) between carbon and fluorine atoms. Furthermore, in the above region, in addition to peaks H and F, there may also be photoelectron peaks based on the 1s orbital of oxygen atoms (O1s) or photoelectron peaks based on the 1s orbital of nitrogen atoms (N1s) (hereinafter also referred to as "other peaks").

[0020] The fluorine atom content ratio [atm%] in the above-mentioned region is preferably 55% or less, more preferably 40% or less. The fluorine atom content ratio is calculated by the following procedure. Within the range of photoelectron peaks containing C1s, O1s, N1s, and F1s in ESCA, the background is subtracted, and the peak intensity of each element (carbon, oxygen, nitrogen, and fluorine atoms) is calculated. For the above four elements, the peak intensity correction value obtained by dividing the peak intensity by the inherent relative sensitivity coefficient of the element is calculated, and the ratio of the peak intensity of fluorine atoms (correction value) in the sum of correction values ​​is taken as the "fluorine atom content ratio".

[0021] Furthermore, on the surface of the original powder, the maximum height of peak H relative to the maximum height of peak F is preferably less than 0.2 times, more preferably less than 0.1 times. Also, the content ratio of fluorine atoms on the surface of the original powder is preferably more than 55%, more preferably more than 60%. According to Method 1, a modified powder with improved surface properties (wetting properties, etc.) and dispersion stability can be obtained without affecting the overall physical properties (electrical properties, etc.) of polymer F. The mechanism of action is not necessarily clear, but is considered as follows.

[0022] Since the plasma treatment in Method 1 is carried out at near atmospheric pressure, in other words, in an atmosphere with high gas density, it is believed that the gases contained in the atmosphere are partially plasmaized. Furthermore, it is believed that the gases contained in the atmosphere not only become plasma themselves, but also form electrically neutral free radicals, etc., which become modifying components of the polymer. That is, it is believed that in the plasma treatment of Method 1, since the plasma treatment is carried out under the above-mentioned conditions, polymer F can be easily and efficiently modified.

[0023] For example, it is believed that if the gas contains a reducing gas with hydrogen atoms, it will not only become plasma itself, but also become electrically neutral hydrogen free radicals. It is believed that, as a result, the hydrogen free radicals act on the CF bonds of the F polymer activated by the plasma, thereby modifying the polymer. It is believed that, in particular, the atomic radius of hydrogen atoms is similar to that of fluorine atoms, placing them in a state where this interaction is easily further enhanced.

[0024] As a result, according to Method 1, non-fluorine atoms or molecules are efficiently introduced into the F polymer contained on the surface of the original powder. Furthermore, the cleavage of the F polymer on the surface of the original powder caused by plasma is suppressed, and its molecular weight reduction is suppressed; therefore, the surface state of the modified F polymer is easily stabilized. It is believed that through the above-mentioned mechanism, according to Method 1, a powder possessing the physical properties of an F polymer and excellent surface properties can be obtained, and a liquid composition with excellent dispersibility can be easily prepared from it.

[0025] The fluorine content of the F polymer is preferably 70 to 76% by mass. Although the F polymer with higher fluorine content has excellent physical properties (electrophysical properties, etc.), its polarity is particularly low, resulting in poor surface properties (wetting properties, etc.) of the original powder. According to this method, the original powder can also be used to obtain a modified powder with improved surface properties without compromising the overall physical properties of the F polymer.

[0026] The melting temperature of polymer F is preferably above 180°C, more preferably 200 to 325°C, and even more preferably 280 to 320°C. The glass transition point of polymer F is preferably 30 to 150°C, and even more preferably 75 to 125°C. Polymer F is preferably polytetrafluoroethylene (PTFE), a polymer (PFA) containing TFE units and perfluoro(alkyl vinyl ether) (PAVE)-based units (PAVE units), or a copolymer (FEP) containing TFE and hexafluoropropylene-based units, particularly preferably PFA or FEP. These polymers may further contain units based on other comonomers.

[0027] As PAVE, it is preferably CF2=CFOCF3, CF2=CFOCF2CF3 or CF2=CFOCF2CF2CF3 (PPVE), and more preferably PPVE. The F polymer is preferably a group containing oxygen atoms. According to this method, modified molded articles with improved surface properties can be easily obtained without damaging the physical properties of the F polymer based on the group.

[0028] The aforementioned atomic groups may exist in the monomer units of the F polymer, or they may exist in the terminal groups of the polymer backbone. Examples of the latter include F polymers having the aforementioned atomic groups as terminal groups derived from polymerization initiators, chain transfer agents, etc. The atomic groups containing oxygen atoms are preferably hydroxyl-containing groups or carbonyl-containing groups, and particularly preferably carbonyl-containing groups.

[0029] The hydroxyl group is preferably an alcoholic hydroxyl group, more preferably -CF2CH2OH or -C(CF3)2OH. The carbonyl group is a group containing a carbonyl group (>C(O)), preferably a carboxyl group, alkoxycarbonyl group, amide group, isocyanate group, carbamate group (-OC(O)NH2), an anhydride residue (-C(O)OC(O)-), amide imine residue (-C(O)NHC(O)-, etc.) or carbonate group (-OC(O)O-), especially an anhydride residue.

[0030] When polymer F contains carbonyl groups, the number of carbonyl groups in polymer F is preferably 10 to 5000 per 1×10⁶ carbon atoms in the main chain, more preferably 100 to 3000, and even more preferably 800 to 1500. Furthermore, the number of carbonyl groups in polymer F can be quantified using the method described in International Publication No. 2020 / 145133.

[0031] Examples of preferred forms of F polymers include: a polymer (1) containing TFE units and PAVE units and having groups containing oxygen atoms; or a polymer (2) containing TFE units and PAVE units, comprising 2.0 to 5.0 mol% PAVE units relative to all monomer units, and not having groups containing oxygen atoms. These polymers, due to the formation of microspheres in the molded article, further facilitate the formation of a modified layer by method 1.

[0032] Polymer (1) is preferably a polymer comprising TFE units, PAVE units, and monomer units having hydroxyl or carbonyl groups. Polymer (1) is preferably comprising, with respect to all units, 90 to 99 mol% TFE units, 0.5 to 9.97 mol% PAVE units, and 0.01 to 3 mol% units based on the aforementioned monomers. Furthermore, the aforementioned monomers are preferably iconic anhydride, citrate anhydride, or 5-norphene-2,3-dicarboxylic anhydride (also known as: bicycloheptenic anhydride; hereinafter also referred to as "NAH"). As a specific example of polymer (1), the polymer described in International Publication No. 2018 / 16644 may be cited.

[0033] The polymer (2) is preferably composed only of TFE units and PAVE units, and contains 95.0 to 98.0 mol% TFE units and 2.0 to 5.0 mol% PAVE units relative to all monomer units. The content of PAVE units in the polymer (2) is preferably 2.1 mol% or more, more preferably 2.2 mol% or more, relative to all monomer units. Furthermore, the polymer (2) does not have oxygen-containing groups, which means that for every 1 × 10⁶ carbon atoms constituting the polymer backbone, the number of oxygen-containing groups in the polymer is less than 500. The number of oxygen-containing groups is preferably less than 100, more preferably less than 50. The lower limit of the number of oxygen-containing groups is usually 0.

[0034] The polymer (2) can be manufactured using polymerization initiators or chain transfer agents that do not produce oxygen-containing groups as end groups of the polymer chain, or it can be manufactured by fluorinating an F polymer having oxygen-containing groups. As a method of fluorination, an example is the method of using fluorine gas (see Japanese Patent Application Publication No. 2019-194314, etc.).

[0035] The original powder preferably contains polymer F. The content of polymer F in the original powder is preferably 80% by mass or more, more preferably 100% by mass. Other components that may be contained in the original powder include: aromatic polyesters, polyamide-imide, thermoplastic polyimide, polyphenylene ether, polyphenylene oxide, and other heat-resistant resins. The D50 of the original powder is preferably 50 μm or less, more preferably 20 μm or less, and even more preferably 8 μm or less. The D50 of the original powder is preferably 0.1 μm or more, more preferably 0.3 μm or more, and even more preferably 1 μm or more. Furthermore, the D90 of the original powder is preferably less than 100 μm, and even more preferably 90 μm or less. If the D50 and D90 of the original powder are within this range, its surface area increases, making it easier to modify the original powder.

[0036] The plasma treatment in Method 1 is carried out in an atmosphere close to atmospheric pressure. Close to atmospheric pressure refers to a pressure of 0.1 ± 0.02 MPa. From the viewpoint of controlling the generation of plasma in the atmosphere and making the hydrogen reduction species more active, the pressure is preferably 0.08 to 0.12 MPa. From the viewpoint of blocking external gases and inhibiting the mixing of components that hinder plasma treatment, it is more preferably above atmospheric pressure (0.101325 MPa) and below 0.12 MPa.

[0037] The plasma treatment in Method 1 is preferably carried out in an atmosphere containing any one of a reducing gas having hydrogen atoms, a vinyl compound, and a vinylidene compound. The reducing gas having hydrogen atoms is preferably hydrogen, ammonia, or a hydrocarbon gas, more preferably hydrogen, ammonia, methane, or ethylene gas. From the viewpoint of its ability to act as a hydrogen reducing agent in the above-described mechanism, hydrogen or ammonia is even more preferred, and hydrogen is the most ideal. Two or more reducing gases may also be used together.

[0038] A vinyl compound refers to a compound represented by the formula CH2=CHR1 (where R1 represents a monovalent organic group). Specific examples include: acrylic acid, acrylates, acrylamide, α-olefins (propylene, 1-butene, etc.), vinyl ethers, vinyl esters, allyl ethers, vinyl chloride, and styrene. Acrylic acid or acrylates are preferred vinyl compounds. Two or more vinyl compounds may be used in combination. A vinylidene compound refers to a compound represented by the formula CH2=CHR2R3 (where R2 and R3 each independently represent a monovalent organic group). Specific examples include: methacrylic acid, methacrylates, methacrylamide, and vinylidene chloride. Methacrylic acid or methacrylates are preferred vinyl compounds. Two or more vinylidene compounds may be used in combination.

[0039] The atmosphere during plasma processing may consist of only one of the above-mentioned gases, or may further include other gases. From the viewpoint of controlling plasma generation, it is preferable to include reducing gases and other gases. Other gases are preferably water vapor, nitrogen, or rare gases. From the above viewpoint, rare gases are more preferred, and helium, argon, or neon are even more preferred, with argon being the most suitable.

[0040] The concentration of a reducing gas containing hydrogen atoms, or a gas containing either a vinyl compound or a vinylidene compound, in the atmosphere of plasma processing is preferably greater than 99% by volume, more preferably 99.5% by volume or more, and even more preferably 99.9% by volume or more. The upper limit of the above gas concentration is 100% by volume. When the atmosphere contains the above gas and a rare gas, the total concentration of the above gas and the rare gas is within the above range. If the gas concentration in the atmosphere is within the above range, the above-mentioned mechanism of action is easily overstimulated. The above atmosphere can be formed by using high-purity gases or by blocking air from the atmosphere of plasma processing described later.

[0041] In the gas composition of the above-mentioned atmosphere, the reducing gas preferably contains 0.1% by volume or more, more preferably more than 1% by volume. In the gas composition of the above-mentioned atmosphere, the reducing gas preferably contains 100% by volume or less, more preferably less than 50% by volume. As a preferred specific example of the gas composition of the above-mentioned atmosphere, examples include: a gas composition containing 75 to 99.5% by volume of rare gases and 0.5 to 25% by volume of hydrogen; a gas composition containing 75 to 99% by volume of rare gases and 1 to 25% by volume of ammonia. Furthermore, these gas compositions preferably do not contain oxygen.

[0042] The plasma treatment in Method 1 is preferably carried out in an atmosphere containing a reducing gas with hydrogen atoms, or in an atmosphere containing a vinyl compound or a vinylidene compound. In the former case, a modified powder formed by introducing hydrogen atoms onto the surface of the modified powder can be obtained; in the latter case, a modified powder formed by introducing polyvinyl compound chains or polyvinylidene compound chains onto the surface of the modified powder can be obtained. Examples of vinyl compounds or vinylidene compounds include acrylic acid, methacrylic acid, methyl acrylate, and methyl methacrylate, with acrylic acid being preferred. In this case, (meth)acrylic acid chains and (meth)acrylate chains are readily and densely introduced onto the surface of the original powder.

[0043] In this case, the concentration (by volume) of the vinyl compound or vinylidene compound in the atmosphere is preferably 1200 to 1400 ppm. Furthermore, from the viewpoint of controlling plasma generation, the atmosphere in this case preferably also contains other gases. The preferred form of these other gases is the same as that of other gases in the atmosphere containing reducing gases with hydrogen atoms described above. Moreover, when the vinyl compound or vinylidene compound is in liquid or solid form, it can also be heated to become a gas or bubbled to generate a gas.

[0044] From the viewpoint of suppressing the mixing of components that hinder plasma treatment, the plasma treatment in Method 1 is preferably carried out in an atmosphere that blocks air (especially oxygen), and more preferably in an atmosphere that completely blocks air. Examples of methods for blocking air include setting the atmospheric pressure during plasma treatment to above atmospheric pressure, and setting barriers in the plasma treatment apparatus to suppress the mixing of air.

[0045] Examples of the plasma treatment method in Method 1 include: preparing the raw powder and performing plasma discharge in a plasma chamber containing a reducing gas or other raw material gas in an atmosphere-like manner; or placing the raw powder between opposing electrodes and supplying a raw material gas in an atmosphere-like manner while performing plasma discharge. The voltage during plasma discharge is preferably 5 to 20 kV. The frequency of the power supply during plasma discharge is preferably 50 Hz to 100 MHz. The discharge power density relative to the electrode area during plasma discharge is preferably 1 to 400 W·min / cm². If plasma discharge is performed under the above discharge conditions, the adhesion of the modified molded article is easily and excellent. For the target raw powder, the discharge time during plasma discharge is preferably 0.1 seconds to 300 minutes.

[0046] The temperature during plasma discharge is preferably between 0 and 300°C, and more preferably between 10 and 50°C. If plasma discharge is performed under the above conditions, it is easy to further introduce hydrogen atoms, or either polyvinyl chloride compound chains or polyvinylene compound chains, into the F polymer present on the surface of the original powder containing the F polymer. This easily results in a modified powder with significantly improved surface properties such as wettability without damaging the overall properties of the F polymer. In particular, if the temperature during plasma discharge is within the above range, it is easier to form a more selective and dense modified layer.

[0047] In Method 1, it is preferable to pre-treat the surface of the original powder in an atmosphere containing rare gases before subjecting the original powder to plasma treatment. This pretreatment allows for the acquisition of a more highly modified powder. The aforementioned atmosphere is preferably free of reducing gases.

[0048] The modified powder obtained by Method 1 has improved surface properties such as wettability, resulting in higher dispersibility in liquid dispersion media. The sedimentation rate of the modified powder is preferably 60% or less, more preferably 50% or less, and even more preferably 40% or less. Furthermore, the sedimentation rate refers to the value calculated using the following formula when the modified powder is dispersed in the desired liquid dispersion medium, 1.3 μL of a dispersion containing 5% by mass of the modified powder is measured into a 1.5 μL microtube (model: 1-7521-01, manufactured by AS ONE), and centrifuged at 13000 rpm for 5 minutes. Furthermore, when no precipitated components are formed, the sedimentation rate is set to 0%. Sedimentation rate [%] = (Height of precipitated components / Overall height of dispersion) × 100

[0049] The liquid dispersion medium may be water or a non-aqueous dispersion medium. As a non-aqueous dispersion medium, it is preferably a liquid compound selected from the group consisting of amides, ketones and esters, and more preferably N-methyl-2-pyrrolidone, γ-butyrolactone, cyclohexanone or cyclopentanone.

[0050] Preferably, the liquid composition comprising the modified powder obtained by method 1 and the liquid composition thereof, wherein the modified powder is dispersed (hereinafter also referred to as "the composition").

[0051] The content of the modified powder in this composition is preferably 1 to 60% by mass, more preferably 10 to 50% by mass. Furthermore, the content of the liquid dispersion medium is preferably 40 to 99% by mass, more preferably 50 to 90% by mass. This composition may also further include inorganic fillers or other resins (polymers) different from polymer F. Due to the excellent wettability and dispersibility of the modified powder, the dispersion stability of this composition is also easily excellent in the above-described case. In particular, even when PTFE is included as another resin, it is easy to prepare a liquid composition with high dispersibility. This liquid composition is preferably prepared by mixing the modified powder with an aqueous dispersion containing PTFE powder.

[0052] The viscosity of this composition is preferably 50 to 1000 mPa·s, more preferably 75 to 500 mPa·s. In this case, the coating properties of this composition are excellent. The thixotropic ratio of this composition is preferably 1.0 to 2.2. In this case, the coating properties and homogeneity of this composition are excellent. Furthermore, the thixotropic ratio is calculated by dividing the viscosity of this composition measured at 30 rpm by the viscosity of this composition measured at 60 rpm.

[0053] The composition has excellent dispersion stability and can form molded articles that do not damage the physical properties of F polymer, have excellent crack resistance, and exhibit strong adhesion to the substrate. If the composition is coated on the surface of the substrate and heated to form a polymer layer containing F polymer (hereinafter also referred to as "F layer (1)"), a laminate having a substrate layer and an F layer can be manufactured.

[0054] In the manufacture of the laminate, it is sufficient to form an F layer (1) on at least one side of the substrate surface. The F layer (1) may be formed on only one side of the substrate or on both sides of the substrate. The surface of the substrate may be surface treated with a silane coupling agent or the like. When coating this composition, coating methods such as spraying, roller coating, spin coating, gravure coating, microgravure coating, gravure offset coating, blade coating, contact coating, bar coating, die coating, Mayer bar coating, and slot die coating can be used.

[0055] The F layer (1) is preferably formed by heating and then calcining the polymer after removing the dispersion medium by heating. More preferably, it is formed by heating the substrate to the temperature at which the dispersion medium volatilizes (100 to 300°C), and then heating the substrate to the temperature range at which the polymer is calcined (300 to 400°C). That is, the F layer (1) is preferably a calcined product containing PTFE and PFA. The thickness of the F layer (1) is preferably 0.1 μm or more, more preferably 1 μm or more. The upper limit of the thickness is 100 μm. Within this range, the F layer with excellent crack resistance can be easily formed. The peel strength between the F layer (1) and the substrate layer is preferably 3 N / cm or more, more preferably 10 N / cm or more, and more preferably 15 N / cm or more. The peel strength is preferably 100 N / cm or less. If this composition is used, the above-mentioned laminate can be easily formed without damaging the physical properties of PTFE in the F layer.

[0056] Examples of materials used as substrates include: copper, aluminum, iron, glass, resin, silicon, and ceramics. Examples of shapes used as substrates include: planar, curved, and uneven shapes, and further, foil, plate, film, and fibrous shapes. Specific examples of laminates include: metal foil laminates having a metal foil and having an F layer (1) on at least one surface of the metal foil, and multilayer films having a polyimide film and having an F layer (1) on both surfaces of the polyimide film. These laminates have excellent electrical properties and other physical properties, making them suitable as printed circuit board materials. Specifically, the above-mentioned laminates can be used to manufacture flexible printed circuit boards or rigid printed circuit boards.

[0057] If the composition is impregnated in a fabric and dried by heating, an impregnated fabric containing F polymer can be obtained. The impregnated fabric can also be described as a coated fabric formed by coating the fabric with F layer (1). The fabric is preferably a glass fiber fabric, carbon fiber fabric, aromatic polyamide fiber fabric or metal fiber fabric, and more preferably a glass fiber fabric or carbon fiber fabric. From the viewpoint of improving the adhesion to F layer (1), the fabric can also be treated with a silane coupling agent. The total content of F polymer in the fabric is preferably 30 to 80% by mass. Examples of methods for impregnating the composition in the fabric include: immersing the fabric in the composition and coating the fabric with the composition.

[0058] The polymer can also be roasted when the woven fabric is dried. As a method of roasting the polymer, an example can be given: a method of passing the woven fabric through a ventilated drying oven at an atmosphere of 300 to 400°C. Furthermore, the drying of woven fabrics and the roasting of polymers can be implemented at one stage. The F layer (1) of the dip-containing woven fabric has excellent characteristics such as higher close bonding (adherence), higher surface smoothness, and less strain with the woven fabric. If the above-mentioned present woven fabric is hot-pressed with the metal foil, a metal foil laminate with higher stripping strength and less likely to warp can be obtained, which can be used well as a printing substrate material.

[0059] Also, a cascade body in which the substrate and the woven fabric layer are sequentially stacked by arranging the woven fabric impregnated with the composition on the surface of the substrate and subjecting it to heating to dry it, thereby forming an impregnated woven fabric layer comprising the F polymer and the woven fabric. The form is not particularly limited, and if a woven fabric impregnated with this dispersion is applied to part or all of the inner wall surface of a member such as a slot, piping, container, etc., and one side of the said member is rotated for heating, then a dip-containing fabric layer may be formed on part or all of the inner wall surface of the member. The fabrication method is also useful as a lining method for inner wall surfaces of members such as slots, piping, containers, etc.

[0060] This composition has excellent dispersion stability as described above mechanism of action and can be efficiently immersed in porous or fibrous materials. As the above-mentioned porous or fibrous material, materials other than the above-mentioned woven fabrics may also be exemplified, specifically: sheet-like, columnar or fibrous materials. These materials can be pretreated with hardening resins, silane coupling agents, etc., and can also be further filled with inorganic fillers and the like. Furthermore, these materials may also combine to form threads, cables, and wires. When pinching is performed, a median layer comprising other polymers such as polyethylene can also be configured. As the morphology of making the formed object by rendering the composition immersed in the above-mentioned materials, an example may be given: The morphology of the composition being immersed in a fibrous material carrying a hardening resin or a hardened product thereof.

[0061] As fibrous materials, examples can be given: carbon fibers, aromatic polyamide fibers, silicon carbide fibers and other high-strength and low-stretch fibers. As hardening resins, the better ones are: epoxy resins, unsaturated polyester resins, polyurethane resins and other thermohardening resins. As a specific example of the above morphology, a composite coil formed by heating the F polymer may be exemplified by enabling the present composition to be immersed in a coil synthesized by a carbon fiber jig loaded with a thermohardening resin. The composite coil is useful as a coil for large structures, ground anchors, oil excavation, cranes, cableways, elevators, agriculture, forestry and aquaculture, and slings.

[0062] The second aspect of the manufacturing method of the present invention (hereinafter also referred to as "method 2") is a method for manufacturing a modified molded article, which involves plasma treatment of the surface layer of a molded article (hereinafter also referred to as the original molded article) having a surface layer containing an F polymer in an atmosphere containing a reducing gas having hydrogen atoms at near atmospheric pressure, thereby manufacturing a modified molded article having a modified layer formed by introducing hydrogen atoms into the F polymer in at least a portion of the surface.

[0063] In Method 2, the maximum height of the peak H of the modified layer is preferably more than 0.2 times, and more preferably more than 1 times, relative to the maximum height of the peak F. Furthermore, the peak H and peak F are the same as described above.

[0064] Furthermore, the fluorine atom content [atm%] in the above-mentioned region is preferably 55% or less, and more preferably 40% or less. The fluorine atom content and procedure are the same as those described above.

[0065] Furthermore, on the surface of the original molded article, the maximum height of its peak H relative to the maximum height of its peak F is preferably less than 0.2 times, more preferably less than 0.1 times. Also, on the surface of the original molded article, the content ratio of fluorine atoms is preferably more than 55%, more preferably more than 60%.

[0066] According to Method 2, a modified molded article containing polymer F can be obtained, having at least a portion of its surface having a modified layer that does not impair the overall physical properties (electrophysical properties, etc.) of the polymer F but exhibits excellent surface properties (wetting properties, etc.). The mechanism of action is not necessarily clear, but is considered as follows: It is believed that the plasma treatment in Method 2 is carried out at near atmospheric pressure, in other words, in an atmosphere with high gas density, thus partially plasmatizing the gases contained in the atmosphere. Furthermore, it is believed that the reducing gases containing hydrogen atoms contained in the atmosphere not only become plasma themselves but also become electrically neutral hydrogen free radicals.

[0067] That is, it is believed that the plasma treatment in Method 2 is in a state where plasma and hydrogen free radicals are present. It is believed that because the plasma treatment is carried out in this state, the hydrogen free radicals act on the CF bonds of the F polymer that are activated by the plasma, thereby forming a modified layer. It is believed that, in particular, the atomic radii of hydrogen atoms and fluorine atoms are similar, and this interaction is easily further enhanced, thereby efficiently forming a modified layer.

[0068] As a result, according to Method 2, a modified layer is formed by efficiently introducing hydrogen atoms into the F polymer contained on the surface of the molded article. Furthermore, it is believed that the cleavage of the F polymer caused by plasma is suppressed by the action of hydrogen free radicals, thus suppressing its molecular weight reduction, thereby forming a modified layer with higher stability. Through the above-mentioned mechanism, it is believed that according to Method 2, a modified molded article can be obtained by forming a modified layer by introducing hydrogen atoms into the F polymer on the surface of a molded article containing an F polymer, thereby possessing both the overall physical properties of the F polymer and the surface physical properties of the molded article.

[0069] The thickness of the modified layer in the modified molded article is preferably less than 1000 nm, more preferably less than 500 nm, and particularly preferably less than 100 nm. The thickness of the modified layer is preferably more than 1 nm. Furthermore, the thickness of the modified layer, when the modified layer has planar extension, refers to the length in the direction perpendicular to the plane; when the modified layer does not have planar extension, it refers to the shortest length.

[0070] The definition and scope of polymer F in this Law 2 are as described above.

[0071] The original molded article in Method 2 is a molded article whose surface layer contains F polymer. Furthermore, the term "surface layer" refers to a region extending from the surface of the molded article towards its thickness direction within a range of at least approximately 1000 nm. The molded article using Method 2 is a molded article whose surface layer contains F polymer. The thickness of the molded article is the same as described above; when the molded article has planar extension, it refers to the length perpendicular to that planar direction; when the molded article does not have planar extension, it refers to the shortest length. The original molded article may contain F polymer entirely, or it may contain F polymer only in its surface layer. Furthermore, in the latter case, the entire surface layer may contain F polymer, or a portion of the surface layer may contain F polymer. The surface shape of the original molded article may be smooth or uneven.

[0072] The original molded article is preferably a molded article having a surface layer containing F polymer, and more preferably a sheet-like molded article having a portion of the surface layer containing F polymer. The thickness of the surface layer containing F polymer is preferably 1 μm or more, more preferably 5 μm or more, and particularly preferably 10 μm or more. The thickness of the layer containing F polymer is preferably 1 mm or less. If the original molded article has a portion of the surface layer containing F polymer of the above-mentioned thickness, then according to this method, a modified molded article possessing the physical properties and surface properties of F polymer as a whole can be easily obtained.

[0073] The original product is preferably a film of F polymer, or a laminate having a substrate layer and a layer containing F polymer (hereinafter also referred to as "F layer (2)") and having F layer (2) on the surface. In the film of F polymer, or in the laminate having F layer (2) on both sides, the method can be applied to both sides, or the method can be applied to only one side. The film of F polymer is preferably made of F polymer as the main component, and preferably contains more than 50% by mass and less than 100% by mass of F polymer.

[0074] Other components that may be contained in the F polymer film include: epoxy resin, maleimide resin, urethane resin, polyimide resin, polyamide-imide resin, polyphenylene ether resin, polyphenylene oxide resin, liquid crystal polyester resin and other heat-resistant resins, nitride fillers, silica fillers, mica fillers, clay fillers, talc fillers and other inorganic fillers, carbon fillers such as carbon fiber, and elastomers.

[0075] The substrate layer in the laminate is preferably a resin substrate layer or a metal substrate layer. Examples of metal substrate layers include metal foil, and examples of materials include alloys of copper, nickel, aluminum, titanium, etc. Examples of resin substrate layers include resin films, and examples of materials include polyimide, polyarylate, polyurethane, polyarylate, polyamide, polyetheramide, polyphenylene sulfide, polyallyl ether ketone, polyamide-amide, liquid crystal polyester, and liquid crystal polyester-amide. Furthermore, examples of resin substrates include prepregs used as precursors for fiber-reinforced resin substrates.

[0076] Preferred forms of the laminate include: a metal foil laminate having a metal foil and an F layer (2) formed on at least one surface thereon, and a multilayer film having a resin film and an F layer (2) formed on at least one surface thereon. The metal foil in the metal foil laminate is preferably copper foil. This metal foil laminate is particularly useful as a printed circuit board material. The resin film in the multilayer film is preferably a polyimide film. This multilayer film is useful as an electrical wire coating material and a printed circuit board material.

[0077] The plasma treatment in Method 2 is carried out in an atmosphere containing a reducing gas containing hydrogen atoms. The reducing gas containing hydrogen atoms is preferably hydrogen, ammonia, or a hydrocarbon gas, more preferably hydrogen, ammonia, methane, or ethylene. From the viewpoint of its ability to act as a hydrogen reducing agent in the above-mentioned mechanism, hydrogen or ammonia is even more preferred, and hydrogen is the most suitable. One reducing gas may be used alone, or two or more may be used in combination.

[0078] The atmosphere during plasma processing may consist only of reducing gases, or may further include other gases. From the viewpoint of controlling plasma generation, it is preferable to include reducing gases and other gases. Other gases are preferably water vapor, nitrogen, or rare gases. From the above viewpoint, rare gases are more preferred, and helium, argon, or neon are even more preferred, with argon being the most suitable.

[0079] The concentration of reducing gas in the atmosphere during plasma treatment (when the atmosphere includes the above-mentioned gas and rare gas, it refers to the total concentration of the above-mentioned gas and rare gas) is preferably greater than 99% by volume, more preferably greater than 99.5% by volume, and even more preferably greater than 99.9% by volume. The upper limit of the above gas concentration is 100% by volume. If the gas concentration in the atmosphere is within the above range, the above-mentioned mechanism of action is easily enhanced. The above atmosphere can be formed by using high-purity gas or by blocking air from the atmosphere of plasma treatment described later.

[0080] In the gas composition of the above-mentioned atmosphere, the reducing gas preferably contains 0.1% by volume or more, more preferably more than 1% by volume. In the gas composition of the above-mentioned atmosphere, the reducing gas preferably contains 100% by volume or less, more preferably less than 50% by volume. As a preferred specific example of the gas composition of the above-mentioned atmosphere, examples include: a gas composition containing 75 to 99.5% by volume of a rare gas and 0.5 to 25% by volume of hydrogen; or a gas composition containing 75 to 99% by volume of a rare gas and 1 to 25% by volume of ammonia. Furthermore, these gas compositions preferably do not contain oxygen.

[0081] The plasma treatment in Method 2 is carried out in an atmosphere close to atmospheric pressure. Near atmospheric pressure refers to a pressure of 0.1 ± 0.02 MPa. From the viewpoint of controlling the generation of plasma in the atmosphere and enhancing the effect of hydrogen reduction, the pressure is preferably 0.08 to 0.12 MPa. From the viewpoint of blocking external gases and suppressing the mixing of components that hinder plasma treatment, it is more preferably between atmospheric pressure (0.101325 MPa) and 0.12 MPa.

[0082] From the viewpoint of suppressing the mixing of components that hinder plasma treatment, the plasma treatment in Method 2 is preferably carried out in an atmosphere that blocks air, especially oxygen, and more preferably in an atmosphere that completely blocks air. Examples of methods for blocking air include: making the atmospheric pressure during plasma treatment above atmospheric pressure, and setting up barriers in the plasma treatment apparatus to suppress the mixing of air.

[0083] Examples of the plasma treatment method in Method 2 include: placing the original molded article in a plasma chamber containing a reducing gas or other raw material gas in an atmosphere-like manner and performing plasma discharge; or placing the original molded article between opposing electrodes, supplying a raw material gas in an atmosphere-like manner, and performing plasma discharge. The voltage during plasma discharge is preferably 5 to 20 kV. The frequency of the power supply during plasma discharge is preferably 50 Hz to 100 MHz. The discharge power density relative to the electrode area during plasma discharge is preferably 1 to 400 W·min / cm². If plasma discharge is performed under the above discharge conditions, the adhesion of the modified molded article is easily improved. For the intended original molded article, the discharge time during plasma discharge is preferably 0.1 seconds to 300 minutes.

[0084] The temperature during plasma discharge is preferably between 0 and 300°C, and more preferably between 10 and 50°C. If plasma discharge is performed under these conditions, hydrogen atoms can be easily introduced into the F polymer present on the surface of the molded article containing the F polymer, easily obtaining a modified molded article with significantly improved surface properties such as wettability without compromising the overall properties of the F polymer. In particular, if the temperature during plasma discharge is within the above range, a more selective and dense modified layer can be easily formed.

[0085] In Method 2, the surface of the original molded article may also be pre-treated with plasma in an atmosphere free of reducing gases before plasma treatment. If the surface of the original molded article is appropriately roughened by this treatment, the contact area between the surface of the molded article and the plasma during the plasma treatment of this method becomes larger, making it easier to form a modified layer with a higher degree of hydrogen atom induction. The aforementioned atmosphere preferably contains rare gases.

[0086] When the original molded article is the above-mentioned laminated body, and it is desired to laminate it with other substrates, if the laminate is performed after the modified layer is formed by applying Method 2 to the F layer (2) of the original molded article, the adhesion strength with other substrates can be improved. For example, if a liquid composition containing F polymer powder is coated on a strip substrate and heated to form F layer (2), an original molded article is prepared, and Method 2 is applied to the F layer (2), and then it is laminated with other strip substrates by a roll-to-roll process, a strip composite substrate can be easily obtained.

[0087] Furthermore, when the original molded article is a long strip laminate in the shape of a roll, the original molded article is rolled out from the roll, and while passing the original molded article between opposing electrodes, a raw material gas is supplied in a manner that creates an atmospheric condition for plasma discharge, thereby obtaining a modified molded article with a modified layer formed thereon. The obtained modified molded article can be directly transferred to the lamination step with other substrates, or it can be temporarily rolled into a roll and then rolled out again and transferred to the lamination step with other substrates. From the viewpoint of simplifying the process, it is preferable to integrate the above-mentioned plasma discharge device into the lamination device, so that the original molded article can be plasma treated before the lamination step.

[0088] The modified molded article of the present invention (hereinafter also referred to as "the molded article") is a molded article having at least a portion of its surface having a modified layer formed by introducing hydrogen atoms into the F polymer, wherein the modified layer is a layer in which the maximum height of the H peak is 0.2 times or more relative to the maximum height of the F peak, and is a layer in which the fluorine atom content in the aforementioned region is 55% or less. The molded article is preferably manufactured by method 2 of the present invention.

[0089] The morphology of the F polymer in this molded article, including the preferred morphology, is the same as that in Method 1. The morphology of the modified layer in this molded article and the state or shape of the surface in this molded article, including the preferred morphology, are the same as that in Method 2. Examples of preferred morphologies of this molded article include: a film having a modified layer on at least one surface of the F polymer film; a metal foil laminate having a metal foil and an F layer (2) formed on at least one surface thereon, and a modified layer on the surface of the F layer (2); and a multilayer film having a resin film and an F layer (2) formed on at least one surface thereon, and a modified layer on the surface of the F layer. When an F layer is formed on both sides of a metal foil laminate, or when an F layer (2) is formed on both sides of a multilayer film, a modified layer may be present on both surfaces. The morphologies of the F polymer film, metal foil, resin film, and F layer (2) in these morphologies, including the preferred morphologies, are the same as those in Method 1.

[0090] This molded article possesses the properties of the F polymer as a whole and the surface properties derived from high polarity, making it particularly useful as a wire coating material and a printed circuit board material. For example, the dielectric constant of the F polymer film or F layer (2) having the modified layer is preferably 2.0 to 3.5, more preferably 2.0 to 3.0. Furthermore, the dielectric constant is measured at a frequency of 10 GHz using a split column dielectric resonator (SPDR) in an atmosphere of 23°C ± 2°C and 50 ± 5% relative humidity. When this molded article is a multilayer film, the dielectric constant of this molded article is preferably 2.0 to 3.5, more preferably 2.0 to 3.0. The water contact angle of the outermost surface (modified layer) of this molded article is preferably 100° or less, more preferably 90° or less. Also, the water contact angle of the outermost surface (modified layer) of this molded article is preferably 10° or more, more preferably 30° or more. Furthermore, the water contact angle is the value measured using the static drop method described in JIS R 3257:1999.

[0091] The surface of the molded article having the modified layer can then be laminated and attached to other substrates. In this case, the peel strength of the interface between the molded article and the other substrate that is the object of lamination is preferably 8 N / cm or more, and more preferably 10 N / cm or more.

[0092] As a method for laminating and bonding this molded article with other substrates, hot pressing can be used as an example. The hot pressing temperature is preferably below the melting point of the polymer, more preferably below 300°C, and even more preferably below 240°C. The hot pressing temperature is preferably above 120°C, and even more preferably above 160°C. Because this molded article has a modified layer with excellent wettability and other physical properties on its surface, it can be laminated and bonded with other substrates at even lower temperatures. Other substrates, in addition to the aforementioned metal substrates and resin substrates, include: prepregs, glass substrates, and ceramic substrates.

[0093] Examples of the structure of the laminate between the molded article and other substrates include: metal substrate / molded article with modified layers on both sides / other substrate layer / molded article with modified layers on both sides / metal substrate, metal substrate layer / other substrate layer / molded article with modified layers on both sides / other substrate layer / metal substrate layer, etc. Each layer may further include glass cloth or filler. The aforementioned laminates are useful as antenna parts, printed circuit boards, aircraft parts, automotive parts, sporting goods, food industry supplies, coatings, cosmetics, etc. Specifically, they are useful as wire covering materials (aircraft wires, etc.), electrical insulating tapes, oil drilling insulating tapes, printed circuit board materials, separation membranes (microfiltration membranes, ultrafiltration membranes, reverse osmosis membranes, ion exchange membranes, dialysis membranes, gas separation membranes, etc.), electrode adhesives (for lithium secondary batteries, fuel cells, etc.), replication rollers, furniture, automotive dashboards, home appliances, etc., outer covers, sliding components (load bearings, sliding shafts, valves, bearings, gears, cams, belt conveyors, food conveyor belts, etc.), tools (shovels, files, awls, saws, etc.), boilers, funnels, pipes, ovens, baking molds, chutes, molds, toilets, and container covering materials.

[0094] The present invention has been described above as follows: this method, methods 1 and 2, and the molded article. However, the present invention is not limited to the configuration of the above embodiments. For example, other arbitrary steps may be added to the present method, methods 1 and 2 in the configuration of the above embodiments, or they may be replaced with any steps that produce the same effect. Furthermore, other arbitrary configurations may be added to the molded article in the configuration of the above embodiments, or it may be replaced with any configuration that performs the same function. Examples

[0095] Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited to these examples. [Example 1] The following raw materials were used in the manufacturing example of the modified powder and liquid composition. F powder 1: Powder containing polymer 1 (melting point: 300°C, fluorine content: 71% by mass) comprising 97.9 mol% TFE units, 2.0 mol% PPVE units and 0.1 mol% NAH units (average particle size: 2.6 μm). Furthermore, F powder 1 corresponds to the resin powder (A) described in paragraph

[0154] of International Publication No. 2018 / 016644. F powder 2: Powder containing polymer 2 (melting point: 300°C, fluorine content: 71% by mass) comprising 98.7 mol% TFE units and 1.3 mol% PPVE units (average particle size: 4.3 μm). Furthermore, polymer 1 has 1000 carbonyl groups per 1×106 carbon atoms in its main chain, while polymer 2 has 40 carbonyl groups per 1×106 carbon atoms in its main chain.

[0096] [Example 1-1] Manufacturing Example of Modified Powder 1 and Liquid Composition 1: F powder 1 is uniformly disposed in a plasma chamber equipped with a mechanism for clamping a dielectric into each of a pair of opposing electrodes, capable of generating plasma by dielectric barrier discharge, and equipped with a platform for holding the powder. A mixed gas containing 95% by volume argon and 5% by volume hydrogen is introduced into the chamber, and external gas is blocked. The total concentration of argon and hydrogen in the chamber during plasma treatment is maintained at 99.9% by volume or higher, the pressure in the chamber is maintained at 0.1 MPa, and the temperature in the chamber is maintained at 25°C. Plasma discharge is performed in the chamber with a processing frequency of 13 kHz and an applied voltage of 9 kV for 1 minute to plasma treat F powder 1, thereby obtaining modified powder 1. 67 parts by mass of distilled water are added relative to 33 parts by mass of modified powder 1, and the mixture is stirred for 60 minutes to obtain a liquid composition 1 containing modified powder 1 and water, free of surfactants, and in which modified powder 1 is dispersed.

[0097] [Example 1-2] Evaluation Example: A mixture containing 1 part by mass of a nonionic fluorinated surfactant (manufactured by NEOS, FTERGENT 250) and 66 parts by mass of distilled water was added to 33 parts by mass of powder 1, and stirred for 60 minutes to obtain a liquid composition C1 in which powder 1 is dispersed. Furthermore, this liquid composition C1 is equivalent to the dispersion (C-1) described in paragraph

[0156] of International Publication No. 2018 / 016644. The "dispersibility" described in the examples of International Publication No. 2018 / 016644 was evaluated for liquid composition 1 and liquid composition C1, and the two liquid compositions showed equal dispersibility.

[0098] [Example 1-3] Manufacturing example of modified powder 2 and liquid composition 2: F powder 1 is changed to F powder 2. Otherwise, modified powder 2 is obtained in the same manner as in Example 1-1, and liquid composition 2 is obtained. [Example 1-4] Manufacturing example of modified powder 3 and liquid composition 3: F powder 1 is changed to F powder 2. External gas is not specifically blocked during plasma discharge. Plasma discharge is carried out when the total concentration of argon and hydrogen in the chamber during plasma treatment does not reach 99.9% and oxygen exceeds 1% by volume. Otherwise, modified powder 3 is obtained in the same manner as in Example 1-1, and liquid composition 3 is obtained.

[0099] [Examples 1-5] Evaluation Example: F powder 1 was changed to F powder 2. Otherwise, liquid composition C2 was prepared in the same manner as in Examples 1-2. The adhesion of the molded articles of liquid compositions 2, 3 and C2 was evaluated by the following procedure. Each liquid composition was coated onto copper foil using a die coating method. The copper foil was then passed through a drying oven at 120°C for 5 minutes to form a dry coating. The polymer was then calcined in a far-infrared oven at 380°C for 10 minutes to prepare a laminate with a polymer layer (10 μm thick) on the surface of the copper foil. A rectangular test piece with a length of 100 mm and a width of 10 mm was cut from the laminate. The copper foil was peeled from one end of the test piece along its length to a position of 50 mm from the polymer layer. During peeling, a 50 mm distance from one end of the specimen along its length was used as the center. A tensile testing machine (manufactured by Orientec) was used to perform a 90-degree peel at a tensile speed of 50 mm / min. The average load over a distance of 10 mm to 30 mm was measured to evaluate the peel strength (N / cm) of the laminate. The peel strength of the laminate formed by liquid composition 2 was 8 N / cm, the peel strength of the laminate formed by liquid composition 3 was 4 N / cm, and the peel strength of the laminate formed by liquid composition C2 was less than 3 N / cm.

[0100] [Example 2] The following raw materials were used in the manufacturing example of the modified membrane. Membrane 1: A membrane of polymer 1 (thickness: 25 μm). Membrane 2: A membrane of polymer 3 (melting point: 305°C, fluorine content: 71% by mass) containing 98.2 mol% TFE units and 1.8 mol% PPVE units (thickness: 25 μm). Furthermore, in both membranes 1 and 2, the peak H (a peak located at 284 eV to 286 eV in the region from the surface of the membrane to a depth of 10 nm) measured by ESCA is weak, and the maximum height of peak H is much less than 0.2 times that of peak F (a peak located at 289 eV to 295 eV in the region from the surface of the membrane to a depth of 10 nm). Also, the fluorine atom content is 60%.

[0101] Furthermore, the surface measurements performed using ESCA were performed using a Quantera II (manufactured by ULVAC-PHI). The X-ray source was a 100 W monochromatic AlKα beam, and an ion gun and a neutralization gun using a barium oxide emitter were employed to prevent the sample surface from becoming charged. The photoelectron detection area was 100 μm, the photoelectron detection angle was 45 degrees, and the transmission energy was 55 eV. The fluorine atom content ratio was calculated based on the intensity of various detected peaks (N1s, O1s, C1s, and F1s orbitals). The depth from the surface was determined based on the sputtering rate of the SiO2 sputtered film using C60 ions as the sputtering ions.

[0102] [Example 2-1] Manufacturing Example of Modified Membrane 1: Membrane 1 is placed in a plasma chamber equipped with a mechanism that clamps a dielectric material into each of a pair of opposing electrodes and is capable of generating plasma by dielectric barrier discharge. A mixed gas containing 95% vol% argon and 5% vol% hydrogen is introduced into the chamber, and external gases are blocked, maintaining the pressure in the chamber at 0.1 MPa and the temperature in the chamber at 25°C. Plasma discharge is performed in the chamber with a processing frequency of 13 kHz and an applied voltage of 9 kV for 2 minutes to treat membrane 1.

[0103] On the surface of the obtained film (modified film 1), the maximum height of peak H is 2.5 times that of peak F, and the fluorine atom content in the above region is 30%. Furthermore, if the surface of modified film 1 is etched 100 nm in the thickness direction and its surface is measured again using ESCA, its distribution is the same as that of film 1, confirming that modified film 1 is a film with a modified layer formed by introducing hydrogen atoms into polymer 1 on its surface.

[0104] [Example 2-2] Manufacturing Example of Modified Membrane 2: The gas sealed in the chamber was changed to a mixed gas containing 94% vol argon, 5% vol argon, and 1% vol argon vapor. Otherwise, the manufacturing process was the same as in Example 1, and the membrane 1 was subjected to plasma treatment. On the surface of the obtained membrane (modified membrane 2), the maximum height of peak H was 0.2 times that of peak F, confirming that modified membrane 2 is a membrane with a modified layer formed by introducing hydrogen atoms into polymer 1 on its surface.

[0105] [Example 2-3] Manufacturing Example of Modified Membrane 3: Membrane 1 is changed to membrane 2. Otherwise, membrane 2 is subjected to plasma treatment in the same manner as in Example 1. In the surface of the obtained membrane (modified membrane 3), the maximum height of peak H is 3 times that of peak F, and the fluorine atom content ratio in the above region is 25%. It is confirmed that modified membrane 3 is a membrane with a modified layer formed by introducing hydrogen atoms into polymer 2 on its surface.

[0106] [Example 2-4] Example of manufacturing modified membrane 4 (comparative example): The gas sealed in the chamber was only argon. Otherwise, the membrane 1 was subjected to plasma treatment in the same manner as in Example 1. The surface state of the obtained membrane (modified membrane 4) measured by ESCA was almost identical to that of membrane 1.

[0107] [Example 2-5] Manufacturing example of modified membrane 5 (comparative example) Under vacuum conditions, membrane 1 was subjected to plasma treatment in the same manner as in Example 1. The surface state of the obtained membrane (modified membrane 5) measured by ESCA was almost identical to that of membrane 1.

[0108] [Example 2-6] Evaluation of Modified Film: Modified film 1 and clean copper foil were placed face-to-face and hot-pressed (temperature: 340°C, pressure: 15 kN / m) to obtain an adhesive laminate of modified film 1 and copper foil. Rectangular test pieces with a length of 100 mm and a width of 10 mm were cut from the adhesive laminate and left to stand at 25°C for 3 months. Then, the copper foil layer was peeled from one end of the test piece along the length direction to a position of 50 mm from the modified film 1 layer. During peeling, the position 50 mm away from one end of the test piece along the length direction was used as the center, and a tensile testing machine (manufactured by Orientec) was used to peel at a tensile speed of 50 mm / min at a 90-degree angle. The average load at a measurement distance of 10 mm to 30 mm was measured and taken as the peel strength (N / cm). Adhesive laminates were also made in the same way for each film, and their peel strength was evaluated. The results are summarized in Table 1.

[0109] [Table 1] Table 1 Membrane 1 Membrane 2 Modified membrane 1 Modified membrane 2 Modified membrane 3 Modified membrane 4 Modified membrane 5 Peel strength (N / cm) 5 <1 13 11 9 7 6 [Industrial Applicability]

[0110] Based on the above results, it is evident that the modified powder prepared by this method is less prone to precipitation, and even without the addition of surfactants, its dispersibility in water remains equivalent to that in the case of adding surfactants. Furthermore, it is known that the molded article formed from a liquid composition containing the modified powder prepared by this method exhibits higher adhesion to the substrate compared to a molded article formed from a liquid composition containing the original powder, demonstrating higher bonding strength. As can be seen from the above, the modified powder prepared by this method undergoes significant surface modification, and the composition containing this modified powder becomes a liquid composition with excellent dispersibility and other liquid properties even without the addition of surfactants, enabling the formation of molded articles with high substrate adhesion. The liquid composition containing the modified powder prepared by this method is a liquid composition with excellent dispersibility and other liquid properties, and can be efficiently impregnated in porous or fibrous materials.

[0111] Furthermore, based on the above results, it is evident that when the modified films 1 to 3, which are modified molded articles produced by this method, are bonded to copper foil, the peel strength is higher than that of the original molded articles 1 or 2 with the copper foil, thus improving the bonding strength. Moreover, compared to the peel strength of modified films 4 and 5 not produced by this method with the copper foil, the peel strength of modified films 1 to 3 produced by this method with the copper foil is higher. In summary, it is clear that the modified molded articles produced by this method undergo a high degree of surface modification. Therefore, it is considered that the laminates of modified molded articles produced by this method with other substrates are useful for antenna components, printed circuit boards, aircraft parts, automotive parts, sporting goods, food industry products, coatings, cosmetics, etc.

Claims

1. A method for manufacturing a modified tetrafluoroethylene polymer, comprising plasma treatment of a tetrafluoroethylene polymer having a melting temperature of 200 to 325°C and containing units based on perfluoro(alkyl vinyl ether) or hexafluoropropylene in an atmosphere that blocks air and is close to atmospheric pressure, thereby obtaining a modified tetrafluoroethylene polymer, wherein the atmosphere is a gas containing hydrogen or ammonia and a rare gas, and the concentration of the gas is 99.9% by volume or more.

2. A method for manufacturing a modified powder, wherein a powder containing a tetrafluoroethylene polymer with a melting temperature of 200 to 325°C and comprising units based on perfluoro(alkyl vinyl ether) or hexafluoropropylene is subjected to plasma treatment in an atmosphere that blocks air and is close to atmospheric pressure, thereby modifying the surface of the powder, wherein the atmosphere is a gas containing hydrogen or ammonia and a rare gas, and the concentration of the gas is 99.9% by volume or more.

3. The manufacturing method of claim 2, wherein the powder is subjected to plasma treatment in an atmosphere that blocks air at near atmospheric pressure to obtain a powder formed by introducing hydrogen atoms into the tetrafluoroethylene polymer, wherein the atmosphere is a gas containing hydrogen or ammonia and a rare gas, and the concentration of the gas is 99.9% by volume or more.

4. The manufacturing method of claim 2 or 3, wherein the powder is pre-treated with plasma in an atmosphere containing rare gases before performing the plasma treatment.

5. The manufacturing method of claim 2 or 3, wherein the above-mentioned tetrafluoroethylene polymer is a tetrafluoroethylene polymer with a fluorine content of 70 to 76% by mass.

6. The manufacturing method of claim 2 or 3, wherein the aforementioned tetrafluoroethylene polymer has a group containing an oxygen atom.

7. A liquid composition comprising a modified powder obtained by any one of claims 2 to 6, and a liquid dispersion medium, wherein the modified powder is dispersed.

8. A method for manufacturing a modified molded article, comprising plasma treatment of the surface layer of a molded article having at least a portion of a surface layer comprising a tetrafluoroethylene-based polymer in an atmosphere that blocks air, thereby manufacturing a modified molded article having a modified layer of thickness of 1 nm to 100 nm formed by introducing hydrogen atoms into the tetrafluoroethylene-based polymer on at least a portion of the surface, wherein the tetrafluoroethylene-based polymer has a melting temperature of 200 to 325°C and contains units based on perfluoro(alkyl vinyl ether) or hexafluoropropylene, wherein the atmosphere is a gas containing hydrogen or ammonia and a rare gas, and the concentration of the gas is 99.9% by volume or more.

9. The manufacturing method of claim 8, wherein the surface layer is pre-treated with plasma in an atmosphere free of reducing gases before performing the plasma treatment.

10. The manufacturing method of claim 9, wherein the aforementioned reducing gas system contains hydrogen, ammonia, or hydrocarbon gas.

11. The manufacturing method of any one of claims 8 to 10, wherein the aforementioned tetrafluoroethylene polymer has a group containing an oxygen atom.

12. A modified molded article comprising a tetrafluoroethylene-based polymer, and having on at least a portion of its surface a modified layer of thickness 1 nm to 100 nm formed by introducing hydrogen atoms into the tetrafluoroethylene-based polymer, which has a melting temperature of 200 to 325°C and comprises units based on perfluoro(alkyl vinyl ether) or hexafluoropropylene, by means of X-ray photoelectron spectroscopy, wherein the maximum height of the peak located at 284 eV to 286 eV in the region from the surface to a depth of 1 nm in the modified layer is more than 0.2 times the maximum height of the peak located at 289 eV to 295 eV in the same region, and the fluorine atom content in the region is less than 55%.