Method for producing surface-modified tetrafluoroethylene polymers, method for producing modified powder, liquid composition, method for producing modified molded articles, and modified molded articles

Abstract

The present invention provides a method for producing modified tetrafluoroethylene polymers and powders by modifying tetrafluoroethylene polymers and powders thereof, and further provides a method for producing modified molded articles in which molded articles of tetrafluoroethylene polymers have been highly surface-modified. [Solution] A method for producing a modified tetrafluoroethylene polymer and powder, comprising plasma treatment of a tetrafluoroethylene polymer and a powder of the polymer in an atmosphere near atmospheric pressure to obtain a surface-modified tetrafluoroethylene polymer, and a method for producing a molded article having a modified layer formed by the introduction of hydrogen atoms into the tetrafluoroethylene polymer on at least a portion of the surface, comprising plasma treatment of the surface layer of a molded article having at least a portion of the surface layer containing a tetrafluoroethylene polymer in an atmosphere near atmospheric pressure containing a reducing gas having hydrogen atoms.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a surface-modified tetrafluoroethylene polymer, a method for producing a modified powder, a liquid composition, a method for producing a modified molded product, and a modified molded product. [Background technology]

[0002] Tetrafluoroethylene polymers have excellent physical properties such as mold release, electrical insulation, water and oil repellency, chemical resistance, weather resistance, and heat resistance, and liquid compositions in which their powder is dispersed are useful as materials that can easily form various molded products (Patent Document 1). However, tetrafluoroethylene polymers have extremely low polarity and poor interaction with other compounds, such as liquid dispersion media, so the dispersibility of their powders is still insufficient. Therefore, modifiers such as surfactants and thickeners are often added to such liquid compositions to improve the dispersibility of the powder and adjust the liquid properties of the composition.

[0003] Furthermore, films made of tetrafluoroethylene polymers have 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 adhesive properties of films made of tetrafluoroethylene polymers are still insufficient. Therefore, surface modification of the film is being considered in order to improve surface properties such as adhesiveness. Patent Document 3 describes a method for introducing peroxide functional groups to the surface of a polytetrafluoroethylene film by plasma treatment in an atmosphere near atmospheric pressure containing a noble gas.

[0004] Furthermore, tetrafluoroethylene polymers are low-polarity polymers with excellent dielectric resistance and dielectric breakdown properties, and the surface of their molded products is not easily modified. In addition, the behavior of tetrafluoroethylene polymers when subjected to plasma treatment is not well understood, and the effects are not stable, and the effects may not be long-lasting.

[0005] Therefore, when plasma treatment of molded products of tetrafluoroethylene polymers, other methods are currently combined. For example, in Patent Document 3, a polytetrafluoroethylene film is plasma-treated to introduce peroxide functional groups to the surface, then immersed in water to introduce hydroxyl groups to the surface, and finally treated with a silane coupling agent to modify the surface of the film. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication 2016 / 159102 Pamphlet [Patent Document 2] International Publication 2019 / 142790 Brochure [Patent Document 3] Japanese Patent Publication No. 2013-049819 [Overview of the project] [Problems that the invention aims to solve]

[0007] The inventors investigated a plasma treatment method for highly modifying the surface of tetrafluoroethylene-based polymer powders. As a result, we found that when the surface of a tetrafluoroethylene polymer powder is treated under predetermined plasma treatment conditions, the surface is modified, and without impairing its physical properties, the surface properties of the powder, such as wettability, and the dispersibility of the liquid composition prepared from it are improved.

[0008] Furthermore, when plasma treating molded articles of tetrafluoroethylene polymers, the inventors investigated plasma treatment conditions that do not require the combination described in Patent Document 3 and that can highly modify the surface of molded articles of tetrafluoroethylene polymers. As a result, they found that when such molded articles are treated under predetermined plasma treatment conditions, a stable layer is formed. They also found that the formation of such a layer improves the wettability of the molded article and improves surface properties such as adhesion without impairing the overall physical properties of the tetrafluoroethylene polymer in the molded article.

[0009] The present invention aims to provide a method for highly modifying tetrafluoroethylene polymers and improving their physical properties. The present invention aims to provide a method for highly surface-modifying a tetrafluoroethylene polymer powder to improve its surface properties, and a liquid composition prepared therefrom that method, which exhibits excellent liquid properties such as dispersibility. The present invention aims to provide a method for highly surface-modifying molded articles of tetrafluoroethylene polymers and improving their surface properties, as well as molded articles of tetrafluoroethylene polymers that have undergone highly surface modification. [Means for solving the problem]

[0010] The present invention has the following aspects. <1> A method for producing a modified tetrafluoroethylene polymer, comprising plasma treatment of a tetrafluoroethylene polymer in an atmosphere near atmospheric pressure to obtain a surface-modified tetrafluoroethylene polymer. <2> A method for producing modified powder, comprising plasma treatment of a tetrafluoroethylene polymer powder in an atmosphere near atmospheric pressure to modify the surface of the powder. <3> The powder is plasma-treated in an atmosphere near atmospheric pressure containing a reducing gas having hydrogen atoms to obtain a powder formed by introducing hydrogen atoms into the tetrafluoroethylene polymer. <2> A method for manufacturing this product. <4> The plasma treatment is performed in an atmosphere that shields the air. <2> or <3> A method for manufacturing this product. <5> Before performing the aforementioned plasma treatment, the powder is pre-treated with plasma in an atmosphere containing a rare gas. <2> from <4> A method for manufacturing this product. <6> The atmosphere includes at least one gas containing hydrogen atoms, a vinyl compound, and a vinylidene compound. <2> from <5> A method for manufacturing this product. <7> The aforementioned atmosphere further contains a noble gas, <2> from <6> A method for manufacturing this product. <8> The pressure near atmospheric pressure is 0.08 to 0.12 MPa, <2> from <7> A method for manufacturing this product. <9> The average particle size of the aforementioned powder is 50 μm or less. <2> from <8> A method for manufacturing this product. <10> The tetrafluoroethylene polymer is a tetrafluoroethylene polymer having a fluorine content of 70 to 76% by mass. <2> from <9> A method for manufacturing this product. <11> The tetrafluoroethylene polymer has an atomic group containing oxygen atoms, <2> from <10> A method for manufacturing this product. <12> the above <2> from <11> A liquid composition comprising a modified powder obtained by any of the following manufacturing methods and a liquid dispersion medium, wherein the modified powder is dispersed. <13> The average particle size of the modified powder is 50 μm or less. <12> A liquid composition. <14> The tetrafluoroethylene polymer is a tetrafluoroethylene polymer having a fluorine content of 70 to 76% by mass. <12> or <13> A liquid composition. <15> The tetrafluoroethylene polymer has an atomic group containing oxygen atoms, <12> from <14> A liquid composition. <16> A method for producing a molded article having at least a part of a surface layer containing a tetrafluoroethylene-based polymer, the method comprising subjecting the surface layer of the molded article to plasma treatment in an atmosphere near atmospheric pressure containing a reducing gas having a hydrogen atom, thereby forming a modified layer in which hydrogen atoms are introduced into the tetrafluoroethylene-based polymer and having the modified layer on at least a part of the surface. <17> The production method according to <16> above, wherein the plasma treatment is performed in an atmosphere shielded from air. <18> The production method according to <16> or <17> above, wherein before performing the plasma treatment, the surface layer is preliminarily subjected to plasma treatment in an atmosphere not containing a reducing gas. <19> The production method according to <16> to <18> above, wherein the reducing gas is hydrogen gas, ammonia gas or hydrocarbon gas. <20> The production method according to <16> to <19> above, wherein the atmosphere for the plasma treatment further contains nitrogen gas or a noble gas. <21> The production method according to <16> to <20> above, wherein the pressure near atmospheric pressure is from 0.08 to 0.12 MPa. <22> The production method according to <16> to <21> above, wherein the molded article having at least a part of a surface layer containing a tetrafluoroethylene-based polymer is a film of a tetrafluoroethylene-based polymer or a laminate having a base material layer and a layer of a tetrafluoroethylene-based polymer. <23> The production method according to <16> to <22> above, wherein the fluorine content of the tetrafluoroethylene-based polymer is from 70 to 76% by mass. <24> The production method according to <16> to <23> above, wherein the tetrafluoroethylene-based polymer has an atomic group containing an oxygen atom. <25> A molded article containing a tetrafluoroethylene-based polymer, having a modified layer in which hydrogen atoms are introduced into the tetrafluoroethylene-based polymer and having the modified layer on at least a part of the 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 measured by X-ray photoelectron spectroscopy is 0.2 times or more the maximum height of the peak at 289 eV to 295 eV in the region, and the content ratio of fluorine atoms in the region is 55% or less. <26> The molded article according to <25> above, wherein the fluorine content of the tetrafluoroethylene-based polymer is 70 to 76% by mass. <27> The molded article according to <25> or <26> above, wherein the tetrafluoroethylene-based polymer has an atomic group containing an oxygen atom. <28> The molded article according to <25> to <27> above, wherein the thickness of the modified layer is less than 1000 nm. <29> The molded article according to <25> to <27> above, wherein the molded article is a film of a tetrafluoroethylene-based polymer or a laminate having a substrate layer and a layer of a tetrafluoroethylene-based polymer.

Advantages of the Invention

[0011] According to the present invention, a highly modified tetrafluoroethylene-based polymer can be produced. According to the present invention, a modified powder of a tetrafluoroethylene-based polymer excellent in wettability and dispersibility can be produced without impairing the physical properties of the tetrafluoroethylene-based polymer, and then a liquid composition excellent in liquid physical properties can be easily produced from the modified powder. From such a liquid composition, a molded article (layered molded article, single film, etc.) having the physical properties of a tetrafluoroethylene-based polymer and excellent in adhesiveness can be easily produced. According to the present invention, a molded article of a tetrafluoroethylene-based polymer having a stable modified layer formed by efficiently introducing hydrogen atoms into at least a part of the surface of the tetrafluoroethylene-based polymer can be produced. Further, a molded article of a tetrafluoroethylene-based polymer having the physical properties of the tetrafluoroethylene-based polymer throughout the molded article and improved surface physical properties such as adhesiveness can be obtained.

Embodiments for Carrying Out the Invention

[0012] The following terms have the following meanings. The "tetrafluoroethylene-based polymer" is a polymer containing a unit based on tetrafluoroethylene (hereinafter also referred to as "TFE") (hereinafter also referred to as "TFE unit"). The glass transition temperature (Tg) of a polymer is a value measured by analyzing the polymer using the dynamic viscoelasticity measurement (DMA) method. The "melting temperature (melting point) of a polymer" is the temperature corresponding to the maximum value of the melting peak measured by differential scanning calorimetry (DSC). "(Meth)acrylate" is a general term for acrylate and methacrylate. "D50" represents the average particle size of the powder, which is the volume-based cumulative 50% diameter of the powder determined by laser diffraction and scattering. In other words, the particle size distribution of the powder is measured by laser diffraction and scattering, and a cumulative curve is obtained with the total volume of the powder collection set to 100%. "D50" is the particle size at the point on that cumulative curve where the cumulative volume reaches 50%. "D90" is the cumulative volume particle size of the powder, and similarly, the volume-based cumulative 90% diameter of the powder, which is determined in the same manner. A "monomer-based unit" refers to an atomic group based on a monomer, formed by the polymerization of the monomer. The unit may be one directly formed by the polymerization reaction, or it may be a unit in which a part of the unit is converted to a different structure by processing the polymer. Hereinafter, a unit based on monomer a will also be simply referred to as a "monomer a unit."

[0013] The present invention provides a method for producing a modified F polymer, which involves plasma treatment of a tetrafluoroethylene polymer (hereinafter also referred to as "F polymer") in an atmosphere near atmospheric pressure to obtain a modified F polymer.

[0014] The first aspect of this Act (hereinafter also referred to as Act 1) is a method for producing a modified powder in which the F polymer is a powder (hereinafter also referred to as the original powder), and the original powder is plasma-treated in an atmosphere near atmospheric pressure to modify the surface of the powder.

[0015] The modified powder preferably has a modified layer formed on its surface by the modification of the F polymer, and 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 a vinyl compound or vinylidene compound into the F polymer.

[0016] In the modified layer formed by introducing hydrogen atoms into the F polymer, the maximum height of the peak (hereinafter also referred to as "peak H") 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 (hereinafter also referred to as "ESCA"), is preferably 0.2 times or more, and more preferably 1 time or more, than the maximum height of the peak (hereinafter also referred to as "peak F") at 289 eV to 295 eV in the same region.

[0017] For surface measurements using ESCA, the Quantera II (ULVAC-PHI) is used. A monochromatic AlKα X-ray source is used at 100W, and a neutralization gun using an ion gun and a barium oxide emitter is employed to prevent charging of the sample surface. The photoelectron detection area is 100 μmφ, the photoelectron detection angle is 45 degrees, and the pass energy is 55 eV. The fluorine atom content can be calculated from the various peak intensities (N1s, O1s, C1s, and F1s orbitals) detected during the measurement. The depth from the surface can be determined based on the sputtering rate of the SiO2 sputtered film, using C60 ions as the sputtering ion.

[0018] Peaks H and F are, in this order, the photoelectron peak based on the 1s orbital of the carbon atom (C1s) and the photoelectron peak based on the 1s orbital of the fluorine atom (F1s). In other words, peak H can be considered to originate from the single bond (CH bond) between the carbon and hydrogen atoms, and peak F can be considered to originate from the single bond (CF bond) between the carbon and fluorine atoms. In addition to peaks H and F, other photoelectron peaks may also exist in the aforementioned region, such as the photoelectron peak based on the 1s orbital of the oxygen atom (O1s) and the photoelectron peak based on the 1s orbital of the nitrogen atom (N1s) (hereinafter also referred to as "other peaks").

[0019] The fluorine atom content [atm%] in the aforementioned region is preferably 55% or less, and more preferably 40% or less. The percentage of fluorine atoms is calculated using the following procedure. In the ESCA spectrum, within the range including the photoelectron peaks of C1s, O1s, N1s, and F1s, the background is subtracted to calculate the peak intensity of each element (carbon, oxygen, nitrogen, and fluorine atoms). A corrected peak intensity value was calculated for each of the four elements by dividing the peak intensity by a relative sensitivity coefficient specific to that element. The ratio of the peak intensity (corrected value) of fluorine atoms to the sum of these corrected values ​​was defined as the "fluorine atom content."

[0020] Furthermore, it is preferable that the maximum height of peak H on the surface of the raw powder is less than 0.2 times, and more preferably 0.1 times or less, than the maximum height of peak F. Furthermore, the surface of the raw powder preferably has a fluorine atom content of more than 55%, and more preferably 60% or more. According to Method 1, a modified powder can be obtained in which the surface properties (wettability, etc.) and dispersion stability are improved without impairing the overall physical properties (electrical properties, etc.) of the F polymer. The mechanism of action is not entirely clear, but it is thought to be as follows.

[0021] Since the plasma treatment in Method 1 is performed near atmospheric pressure, in other words, in an atmosphere with high gas density, it is thought that the gas contained in the atmosphere will be partially plasma-fied. Furthermore, it is thought that the gas contained in the atmosphere will not only become plasma itself, but will also form electrically neutral radicals and other components that modify the polymer. In other words, in the plasma treatment described in Method 1, the plasma treatment proceeds under these conditions, making it likely that the F polymer will be efficiently modified.

[0022] For example, if a reducing gas containing hydrogen atoms is present in the gas, it is thought that not only will it itself become a plasma, but it will also become electrically neutral hydrogen radicals. As a result, it is thought that the hydrogen radicals act on the CF bonds of the plasma-activated F polymer, thereby modifying the polymer. In particular, the atomic radii of hydrogen atoms and fluorine atoms are approximately the same, so this effect is thought to be even more easily enhanced in this environment.

[0023] As a result, according to Method 1, it is believed that 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 by plasma is suppressed, and its reduction in molecular weight is inhibited, so the surface state of the modified F polymer is more stable. According to this mechanism of action, the present method 1 yields a powder possessing the physical properties and excellent surface properties of the F polymer, from which a liquid composition with excellent dispersibility can be easily prepared.

[0024] The fluorine content of the F polymer is preferably 70 to 76% by mass. While F polymers with such high fluorine content exhibit excellent physical properties (electrical properties, etc.), their polarity is particularly low, resulting in poor surface properties (wettability, etc.) of the original powder. According to this method, even with such an original powder, a modified powder can be obtained in which the surface properties are improved without impairing the overall physical properties of the F polymer.

[0025] The melting temperature of the F polymer is preferably 180°C or higher, more preferably 200 to 325°C, and more preferably 280 to 320°C. The glass transition temperature of the F polymer is preferably 30 to 150°C, and more preferably 75 to 125°C. The F polymer is preferably polytetrafluoroethylene (PTFE), a polymer containing TFE units and perfluoro(alkyl vinyl ether) (PAVE)-based units (PAVE units) (PFA), or a copolymer containing TFE and hexafluoropropylene-based units (FEP), with PFA or FEP being particularly preferred. These polymers may further contain units based on other comonomers.

[0026] For PAVE, CF2=CFOCF3, CF2=CFOCF2CF3, or CF2=CFOCF2CF2CF3 (PPVE) are preferred, with PPVE being more preferred. The F polymer preferably has an atomic group containing oxygen atoms. According to this method, a modified molded product with further improved surface properties can be obtained without impairing the physical properties of the F polymer based on such an atomic group.

[0027] The atomic group may be contained in monomer units in the F polymer, or it may be contained in the end groups of the polymer's main chain. An example of the latter is an F polymer having the atomic group as an end group derived from a polymerization initiator, a chain transfer agent, or the like. The group of atoms containing oxygen atoms is preferably a hydroxyl group-containing group or a carbonyl group-containing group, and a carbonyl group-containing group is particularly preferred.

[0028] The hydroxyl group-containing group is preferably a group containing an alcoholic hydroxyl group, and more preferably -CF2CH2OH or -C(CF3)2OH. The carbonyl group-containing group is a group containing a carbonyl group (>C(O)), and is preferably a carboxyl group, alkoxycarbonyl group, amide group, isocyanate group, carbamate group (-OC(O)NH2), acid anhydride residue (-C(O)OC(O)-), imide residue (-C(O)NHC(O)-, etc.), or carbonate group (-OC(O)O-), with acid anhydride residue being particularly preferred.

[0029] If polymer F has carbonyl group-containing groups, the number of carbonyl group-containing groups in polymer F is 1 × 10⁶ carbon atoms in the main chain. 6 The number of carbonyl group-containing groups per polymer is preferably 10 to 5000, more preferably 100 to 3000, and even more preferably 800 to 1500. The number of carbonyl group-containing groups in the F polymer can be quantified by the method described in International Publication No. 2020 / 145133.

[0030] Preferred embodiments of the F polymer include a polymer (1) containing TFE units and PAVE units and having an atomic group containing oxygen atoms, or a polymer (2) containing TFE units and PAVE units, containing 2.0 to 5.0 mol% PAVE units relative to the total monomer units, and not having an atomic group containing oxygen atoms. These polymers form microspherulites in the molded product, which further facilitates the formation of the modified layer by the present method 1.

[0031] The polymer (1) is preferably a polymer comprising TFE units, PAVE units, and monomer units having a hydroxyl group-containing group or a carbonyl group-containing group. The polymer (1) preferably contains 90 to 99 mol% TFE units, 0.5 to 9.97 mol% PAVE units, and 0.01 to 3 mol% units based on the monomers, relative to the total number of units. Furthermore, the monomer is preferably itaconic anhydride, citraconic anhydride, or 5-norbornene-2,3-dicarboxylic acid anhydride (also known as Hymic anhydride; hereinafter also referred to as "NAH"). A specific example of polymer (1) is the polymer described in International Publication No. 2018 / 16644.

[0032] The polymer (2) consists only of TFE units and PAVE units, and preferably contains 95.0 to 98.0 mol% of TFE units and 2.0 to 5.0 mol% of PAVE units relative to the total monomer units. The PAVE unit content in polymer (2) is preferably 2.1 mol% or more, and more preferably 2.2 mol% or more, relative to the total monomer units. Furthermore, polymer (2) not having an atomic group containing oxygen atoms means that the number of carbon atoms constituting the polymer backbone is 1 × 10⁻¹⁶. 6 This means that the number of oxygen-containing atomic groups in the polymer per molecule is less than 500. Preferably, the number of oxygen-containing atomic groups is 100 or less, and more preferably less than 50. The lower limit for the number of oxygen-containing atomic groups is usually 0.

[0033] Polymer (2) may be produced using polymerization initiators, chain transfer agents, etc., that do not produce atomic groups containing oxygen atoms as terminal groups of polymer chains, or it may be produced by fluorinating an F polymer having atomic groups containing oxygen atoms. Examples of fluorination methods include using fluorine gas (see Japanese Patent Publication No. 2019-194314, etc.).

[0034] The raw powder is preferably composed of F polymer. The F polymer content in the raw powder is preferably 80% by mass or more, and more preferably 100% by mass. Other components that may be included in the raw powder include heat-resistant resins such as aromatic polyesters, polyamide-imides, thermoplastic polyimides, polyphenylene ethers, and polyphenylene oxides. The D50 of the raw 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 raw powder is preferably 0.1 μm or more, more preferably 0.3 μm or more, and even more preferably 1 μm or more. The D90 of the raw powder is preferably less than 100 μm, and even more preferably 90 μm or less. When the D50 and D90 of the raw powder are within these ranges, the surface area increases, and the modification of the raw powder proceeds more easily.

[0035] The plasma treatment in Method 1 is carried out in an atmosphere near atmospheric pressure. Near atmospheric pressure is a pressure of 0.1 ± 0.02 MPa. From the viewpoint of controlling plasma generation in the atmosphere and enhancing the action of hydrogen reducing species, the pressure is preferably between 0.08 and 0.12 MPa, and from the viewpoint of shielding from outside air and suppressing the inclusion of components that hinder plasma treatment, it is more preferably between atmospheric pressure (0.101325 MPa) and 0.12 MPa.

[0036] The plasma treatment in Method 1 is preferably carried out in an atmosphere containing a gas that includes one of the following: a reducing gas having hydrogen atoms, a vinyl compound, or a vinylidene compound. Preferred reducing gases having hydrogen atoms include hydrogen gas, ammonia gas, or hydrocarbon gases; more preferably hydrogen gas, ammonia gas, methane gas, or ethylene gas; and from the viewpoint of their ability as hydrogen reducing species in the above-described mechanism, hydrogen gas or ammonia gas is even more preferred, with hydrogen gas being the most preferred. Two or more reducing gases may be used in combination.

[0037] Vinyl compounds are defined by the formula CH2=CHR. 1 Compounds represented by (R in the formula) 1 This represents a monovalent organic group. Specific examples include acrylic acid, acrylate, acrylamide, α-olefin (propylene, 1-butene, etc.), vinyl ether, vinyl ester, allyl ether, vinyl chloride, and styrene. The vinyl compound is preferably acrylic acid or acrylate. Two or more vinyl compounds may be used in combination. A vinylidene compound is defined by the formula CH2=CHR 2 R 3 Compounds represented by (R in the formula) 2 and R 3 Each of these independently exhibits a monovalent organic group. Specific examples include methacrylic acid, methacrylate, methacrylamide, and vinylidene chloride. The vinyl compound is preferably methacrylic acid or methacrylate. Two or more vinylidene compounds may be used in combination.

[0038] The atmosphere in plasma processing may consist of only one of the above-mentioned gases, or it may also contain other gases. From the viewpoint of controlling plasma generation, it is preferable to contain a reducing gas and other gases. The other gas is preferably water vapor, nitrogen gas, or a noble gas. From the aforementioned viewpoint, it is more preferably a noble gas, even more preferably helium gas, argon gas, or neon gas, and most preferably argon gas.

[0039] In plasma processing, the concentration of a reducing gas containing hydrogen atoms, or a gas containing either a vinyl compound or a vinylidene compound, in the atmosphere is preferably greater than 99% by volume, more preferably 99.5% by volume or higher, and even more preferably 99.9% by volume or higher. The upper limit of the gas concentration is 100% by volume. If the atmosphere contains the gas and a noble gas, the total concentration of the gas and the noble gas should be within this range. The aforementioned mechanism of action is likely to be enhanced if the gas concentration in the atmosphere is within the specified range. Such an atmosphere can be created by using high-purity gases or by shielding the air from the atmosphere during plasma processing, as described later.

[0040] The gas composition of the aforementioned atmosphere preferably contains 0.1% or more by volume of a reducing gas, and more preferably more than 1% by volume. The gas composition of the aforementioned atmosphere preferably contains 100% or less by volume of a reducing gas, and more preferably less than 50% by volume. Suitable specific examples of the gas composition of the aforementioned atmosphere include a gas composition containing a noble gas and hydrogen gas in the following order: 75 to 99.5% by volume and 0.5 to 25% by volume, and a gas composition containing a noble gas and ammonia gas in the following order: 75 to 99% by volume and 1 to 25% by volume. Furthermore, it is preferable that oxygen gas is not included in these gas compositions.

[0041] In Method 1, the plasma treatment is preferably carried out in a gas atmosphere containing a reducing gas having hydrogen atoms, or in a gas atmosphere containing the vinyl compound or vinylidene compound. In the former case, a modified powder is obtained in which hydrogen atoms are introduced to the surface of the modified powder, and in the latter case, a modified powder is obtained in which polyvinyl compound chains or polyvinylidene compound chains are introduced to the surface of the modified powder. 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, it is easy to introduce dense (meth)acrylic chains and (meth)acrylate chains onto the surface of the raw powder.

[0042] In this case, the content concentration (volume basis) of the vinyl compound or vinylidene compound in the gas atmosphere is preferably from 1200 to 1400 ppm. Also, in this case, from the viewpoint of controlling the generation of plasma, it is preferable that the gas atmosphere further contains other gases. A preferred embodiment of the other gas is the same as that of the other gas in the atmosphere containing a reducing gas having a hydrogen atom described above. When the vinyl compound or vinylidene compound is in a liquid or solid state, it may be heated to be used in a gaseous state, or bubbled to generate a gas.

[0043] The plasma treatment in Method 1 is preferably carried out in an atmosphere in which air (especially oxygen gas) is shielded, and more preferably carried out in an atmosphere in which air is completely shielded, from the viewpoint of suppressing the mixing of components that inhibit the plasma treatment. Examples of the method of shielding air include a method of making the atmospheric pressure in the plasma treatment equal to or higher than the atmospheric pressure, and a method of installing a barrier wall in the plasma treatment apparatus to suppress the mixing of air.

[0044] Examples of the method of plasma treatment in Method 1 include a method of arranging the raw powder and performing plasma discharge in a plasma chamber filled with a raw material gas such as a reducing gas so as to achieve the atmospheric conditions, and a method of arranging the raw powder between opposing electrodes and performing plasma discharge while supplying the raw material gas so as to achieve the atmospheric conditions. The voltage during plasma discharge is preferably from 5 to 20 kV. The frequency of the power supply during plasma discharge is preferably from 50 Hz to 100 MHz. The discharge power density with respect to the electrode area during plasma discharge is preferably from 1 to 400 W·min / cm 2 When plasma discharge is performed under the above discharge conditions, the modified molded product is likely to have excellent adhesiveness. The discharge time during plasma discharge is preferably from 0.1 second to 300 minutes with respect to the target raw powder.

[0045] The temperature during plasma discharge is preferably from 0 to 300 °C, and more preferably from 10 to 50 °C. When plasma discharge is performed under these conditions, hydrogen atoms, polyvinyl compound chains, or polyvinylidene compound chains are more easily introduced into the F polymer present on the surface of the raw powder containing the F polymer. This makes it easier to obtain a modified powder with highly improved surface properties such as wettability without impairing 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.

[0046] In Method 1, it is preferable to pre-treat the surface of the raw powder with plasma in an atmosphere containing a noble gas before plasma treatment of the raw powder. Such pre-treatment yields a more highly modified powder. It is preferable that such an atmosphere does not contain reducing gases.

[0047] The modified powder obtained by this method 1 has improved surface properties such as wettability and high dispersibility in liquid dispersion media. The settling rate of the modified powder is preferably 60% or less, more preferably 50% or less, and even more preferably 40% or less. The settling rate is calculated using the following formula when the modified powder is dispersed in the target liquid dispersion medium, 1.3 μL of the dispersion containing 5% by mass of the modified powder is measured into a 1.5 μL microtube (model number: 1-7521-01, manufactured by AS ONE Corporation), and centrifuged at 13,000 rpm for 5 minutes. If no settling occurs, the settling rate is considered to be 0%. Settling rate [%] = (Height of settled components / Total height of dispersion) × 100

[0048] The liquid dispersion medium may be water or a non-aqueous dispersion medium. The non-aqueous dispersion medium is preferably one or more liquid compounds selected from the group consisting of amides, ketones, and esters, with N-methyl-2-pyrrolidone, γ-butyrolactone, cyclohexanone, or cyclopentanone being more preferred.

[0049] It is preferable to prepare a liquid composition (hereinafter also referred to as "the composition") which contains the modified powder obtained by Method 1 and a liquid composition in which the modified powder is dispersed.

[0050] The content of the modified powder in this composition is preferably 1 to 60% by mass, and more preferably 10 to 50% by mass. The content of the liquid dispersion medium is preferably 40 to 99% by mass, and more preferably 50 to 90% by mass. This composition may further contain an inorganic filler or other resins (polymers) different from the F polymer. Because the modified powder has excellent wettability and dispersibility, this composition tends to have excellent dispersion stability even in such cases. In particular, even when PTFE is included as the other resin, it is easy to prepare a liquid composition with high dispersibility. Such a liquid composition is preferably prepared by mixing an aqueous dispersion containing the modified powder and PTFE powder.

[0051] The viscosity of this composition is more preferably 50 to 1000 mPa·s, and more preferably 75 to 500 mPa·s. In this case, the composition exhibits excellent coating properties. The thixotropy ratio of this composition is more preferably 1.0 to 2.2. In this case, the composition exhibits excellent coating properties and homogeneity. The thixotropy ratio is calculated by dividing the viscosity of the composition measured at a rotation speed of 30 rpm by the viscosity of the composition measured at a rotation speed of 60 rpm.

[0052] This composition exhibits excellent dispersion stability and allows for the formation of molded articles with excellent crack resistance and strong adhesion to the substrate without impairing the physical properties of the F polymer. By applying this composition to the surface of a substrate and heating it, a polymer layer containing the F polymer (hereinafter also referred to as "F layer (1)") can be formed, thereby producing a laminate having a substrate layer and an F layer.

[0053] In the manufacturing of the laminate, it is sufficient for the F layer (1) to be formed on at least one side of the substrate surface, or it may be formed on only one side of the substrate, or it may be formed on both sides of the substrate. The surface of the substrate may be surface-treated with a silane coupling agent or the like. When applying this composition, the following application methods can be used: spray method, roll coating method, spin coating method, gravure coating method, microgravure coating method, gravure offset method, knife coating method, kiss coating method, bar coating method, die coating method, fountain-mayer bar method, and slot die coating method.

[0054] The F layer (1) is preferably formed by removing the dispersion medium by heating and then firing the polymer by heating. It is particularly preferable to heat the substrate to a temperature at which the dispersion medium volatilizes (100 to 300°C), and then further heat the substrate to a temperature range at which the polymer is fired (300 to 400°C). In other words, the F layer (1) preferably contains fired PTFE and PFA. The thickness of the F layer (1) is preferably 0.1 μm or more, and more preferably 1 μm or more. The upper limit of the thickness is 100 μm. Within this range, an 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 even more preferably 15 N / cm or more. The above peel strength is preferably 100 N / cm or less. Using this composition, such a laminate can be easily formed without impairing the physical properties of PTFE in the F layer.

[0055] Examples of substrate materials include copper, aluminum, iron, glass, resin, silicon, and ceramics. The substrate shape can be planar, curved, or uneven, and may also be foil-like, plate-like, film-like, or fibrous. Specific examples of laminates include a metal-clad laminate having a metal foil and an F layer (1) on at least one surface of the metal foil, and a polyimide film and a multilayer film having an F layer (1) on both surfaces of the polyimide film. These laminates exhibit excellent properties, including electrical characteristics, and are suitable as printed circuit board materials. Specifically, such laminates can be used in the manufacture of flexible printed circuit boards and rigid printed circuit boards.

[0056] By impregnating a woven fabric with this composition and drying it by heating, an impregnated woven fabric in which the F polymer is impregnated is obtained. The impregnated woven fabric can also be called a coated woven fabric in which the woven fabric is covered with the F layer (1). The woven fabric is preferably a glass fiber woven fabric, a carbon fiber woven fabric, an aramid fiber woven fabric, or a metal fiber woven fabric, with glass fiber woven fabric or a carbon fiber woven fabric being more preferred. The woven fabric may be treated with a silane coupling agent from the viewpoint of improving adhesion with the F layer (1). The total content of the F polymer in this woven fabric is preferably 30 to 80% by mass. Methods for impregnating the woven fabric with this composition include immersing the woven fabric in this composition and coating the woven fabric with this composition.

[0057] When drying the woven fabric, the polymer may be calcined. One method for calcining the polymer is to pass the woven fabric through a ventilated drying oven in an atmosphere of 300 to 400°C. Note that the drying of the woven fabric and the calcination of the polymer may be carried out in a single step. The impregnated woven fabric has excellent properties such as high adhesion between the F layer (1) and the woven fabric, high surface smoothness, and low distortion. By heat-pressing this woven fabric with metal foil, a metal-clad laminate with high peel strength and low warping can be obtained, which can be suitably used as a printed circuit board material.

[0058] Alternatively, a woven fabric impregnated with this composition may be placed on the surface of a substrate, heated, and dried to form an impregnated woven fabric layer containing the F polymer and the woven fabric, thereby producing a laminate in which the substrate and the impregnated woven fabric layer are stacked in this order. The embodiment is not particularly limited, and by applying a woven fabric impregnated with this dispersion to part or all of the inner wall surface of a component such as a tank, pipe, or container, and heating the component while rotating it, an impregnated woven fabric layer can be formed on part or all of the inner wall surface of the component. This manufacturing method is also useful as a lining method for the inner wall surface of a component such as a tank, pipe, or container.

[0059] As described above, this composition has excellent dispersion stability and can efficiently impregnate porous or fibrous materials. Examples of such porous or fibrous materials include materials other than the woven fabrics mentioned above, specifically, plate-shaped, columnar, or fibrous materials. These materials may be pre-treated with a curable resin, silane coupling agent, etc., and may be further filled with inorganic fillers, etc. These materials may also be twisted together to form yarn, cables, or wires. When twisting, an intervening layer made of another polymer such as polyethylene may be placed. One embodiment of manufacturing a molded product by impregnating such a material with this composition is to impregnate a fibrous material on which a curable resin or its cured product is supported with this composition.

[0060] Examples of fibrous materials include high-strength, low-elongation fibers such as carbon fibers, aramid fibers, and silicon carbide fibers. Preferred curable resins are thermosetting resins such as epoxy resins, unsaturated polyester resins, and polyurethane resins. A specific example of this embodiment is a composite cable formed by impregnating a cable made of twisted carbon fibers supported with a thermosetting resin with the composition, and then heating it to bake the F polymer. Such a composite cable is useful as a cable for large structures, ground anchors, oil drilling, cranes, cableways, elevators, agriculture, forestry and fisheries, and lifting ropes.

[0061] A 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 having a modified layer formed by the introduction of hydrogen atoms into the F polymer on at least a portion of the surface, wherein the surface layer of a molded article having at least a portion of the surface layer containing an F polymer (hereinafter also referred to as the original molded article) is plasma-treated in an atmosphere near atmospheric pressure containing a reducing gas having hydrogen atoms.

[0062] In Method 2 of this Act, it is preferable that the maximum height of peak H in the modified layer is 0.2 times or more, and more preferably 1 time or more, than the maximum height of peak F. Peaks H and F are the same as described above.

[0063] Furthermore, the fluorine atom content [atm%] in the aforementioned region is preferably 55% or less, and more preferably 40% or less. The proportion of fluorine atoms and the procedure are the same as described above.

[0064] Furthermore, it is preferable that the maximum height of peak H on the surface of the original molded product is less than 0.2 times the maximum height of peak F, and more preferably 0.1 times or less. Furthermore, the surface of the original molded product preferably has a fluorine atom content of more than 55%, and more preferably 60% or more.

[0065] According to this method 2, a modified molded article containing F polymer can be obtained, which has a modified layer on at least a portion of its surface that has excellent surface properties (wettability, etc.) without impairing the overall physical properties (electrical properties, etc.) of the F polymer. The mechanism of action is not entirely clear, but it is thought to be as follows. Since the plasma treatment in Method 2 is performed near atmospheric pressure, in other words, in an atmosphere with high gas density, it is thought that the gas contained in the atmosphere will be partially plasma-fied. Furthermore, it is thought that reducing gases containing hydrogen atoms contained in the atmosphere will not only become plasma themselves, but also become electrically neutral hydrogen radicals.

[0066] In other words, in the plasma treatment described in Method 2, it is considered that plasma and hydrogen radicals are present. As the plasma treatment proceeds in this state, it is thought that hydrogen radicals act on the CF bonds of the plasma-activated F polymer, forming a modified layer. In particular, since the atomic radii of hydrogen atoms and fluorine atoms are approximately the same, this effect is more easily enhanced, and it is thought that the modified layer was formed efficiently.

[0067] As a result, according to Method 2, it is believed that a modified layer is formed in which hydrogen atoms are efficiently introduced into the F polymer contained on the surface of the molded product. Furthermore, it is believed that the cleavage of the F polymer by plasma is suppressed by the action of hydrogen radicals, and its reduction to a lower molecular weight is suppressed, thus forming a highly stable modified layer. According to this mechanism, the present method 2 is thought to produce a modified molded product that is an F polymer molded product possessing the physical properties and surface properties of the F polymer as a whole, by forming a modified layer on the surface of a molded product containing an F polymer in its surface layer, in which hydrogen atoms are introduced into the F polymer.

[0068] The thickness of the modified layer in the modified molded product is preferably less than 1000 nm, more preferably 500 nm or less, and particularly preferably 100 nm or less. The thickness of the modified layer is preferably 1 nm or more. Note that the thickness of the modified layer is the length perpendicular to the plane if the modified layer has a planar extent, and the shortest length if the modified layer does not have a planar extent.

[0069] The definition and scope of F polymers in Article 2 of this Act are as described above.

[0070] In this Act 2, the original molded product is a molded product containing F polymer in its surface layer. The surface layer of a molded product is the region extending at least approximately 1000 nm from the surface of the molded product in the thickness direction, and the molded product to which this Act 2 applies is a molded product containing F polymer in its surface layer. The thickness of a molded product is, as described above, the length perpendicular to the plane if the molded product has a planar extension, and the shortest length if it does not have a planar extension. The original molded product may contain F polymer throughout, or it may contain F polymer only on the surface. In the latter case, the F polymer may be contained throughout the entire surface, or it may be contained only on a part of the surface. The surface shape of the original molded product may be smooth or uneven.

[0071] The original molded product is preferably a molded product having a layer containing F polymer on its surface, and more preferably a sheet-like molded product having a layer portion containing F polymer on its surface. The thickness of the layer containing the F polymer on the surface 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 the F polymer is preferably 1 mm or less. If the original molded product has a layer portion containing the F polymer on the surface of such thickness, a modified molded product possessing the physical properties and surface properties of the F polymer throughout the molded product can be easily obtained by this method.

[0072] The original molded product is preferably a laminate having an F polymer film or a base layer and a layer containing the F polymer (hereinafter also referred to as "F layer (2)"), with the F layer (2) having on its surface. In the case of an F polymer film or a laminate having the F layer (2) on both sides, the present method may be applied to both sides or to only one side. The F polymer film preferably has F polymer as its main component, and preferably contains more than 50% by mass and 100% by mass or less of F polymer.

[0073] Other components that may be included in the F polymer film include heat-resistant resins such as epoxy resins, maleimide resins, urethane resins, polyimide resins, polyamideimide resins, polyphenylene ether resins, polyphenylene oxide resins, and liquid crystal polyester resins; inorganic fillers such as nitride fillers, silica fillers, mica fillers, clay fillers, and talc fillers; carbon fillers such as carbon fibers; and elastomers.

[0074] In the laminate, the substrate layer is preferably a resin substrate layer or a metal substrate layer. Examples of metal substrate layers include metal foils, and their materials include copper, nickel, aluminum, titanium, and alloys thereof. Examples of resin substrates include resin films, and their materials include polyimide, polyarylate, polysulfone, polyallylsulfone, polyamide, polyetheramide, polyphenylene sulfide, polyallyl ether ketone, polyamide imide, liquid crystalline polyester, and liquid crystalline polyesteramide. Another example of a resin substrate is a prepreg, which is a precursor to a fiber-reinforced resin substrate.

[0075] Preferred embodiments of the laminate include a metal-clad laminate having a metal foil and an F layer (2) formed on at least one of its surfaces, and a multilayer film having a resin film and an F layer (2) formed on at least one of its surfaces. In a metal-clad laminate, the metal foil is preferably copper foil. Such a metal-clad laminate is particularly useful as a printed circuit board material. In a multilayer film, the resin film is preferably polyimide film. Such a multilayer film is useful as a wire coating material and a printed circuit board material.

[0076] The plasma treatment in Method 2 is carried out in an atmosphere containing a reducing gas that has hydrogen atoms. Preferably, the reducing gas containing hydrogen atoms is hydrogen gas, ammonia gas, or hydrocarbon gas; more preferably, hydrogen gas, ammonia gas, methane gas, or ethylene gas; and from the viewpoint of its ability as a hydrogen reducing species in the mechanism of action described above, hydrogen gas or ammonia gas is even more preferred, and hydrogen gas is most preferred. The reducing gas may be used alone or in combination of two or more types.

[0077] The atmosphere in plasma processing may consist only of a reducing gas, or it may also contain other gases. From the viewpoint of controlling plasma generation, it is preferable to contain a reducing gas and other gases. The other gas is preferably water vapor, nitrogen gas, or a noble gas. From the aforementioned viewpoint, a noble gas is more preferable, helium gas, argon gas, or neon gas is even more preferable, and argon gas is most preferable.

[0078] The concentration of reducing gas in the atmosphere during plasma processing (or the total concentration of the gas and noble gas if the atmosphere includes the aforementioned gas and noble gas) is preferably greater than 99% by volume, more preferably 99.5% by volume or higher, and even more preferably 99.9% by volume or higher. The upper limit of the gas concentration is 100% by volume. When the gas concentration in the atmosphere is within this range, the above-described mechanism of action is easily enhanced. Such an atmosphere can be created by using a high-purity gas or by shielding the air from the atmosphere during plasma processing, as described later.

[0079] The gas composition of the aforementioned atmosphere preferably contains 0.1% or more by volume of a reducing gas, and more preferably more than 1% by volume. The gas composition of the aforementioned atmosphere preferably contains 100% or less by volume of a reducing gas, and more preferably less than 50% by volume. Suitable specific examples of the gas composition of the aforementioned atmosphere include a gas composition containing a noble gas and hydrogen gas in the following order: 75 to 99.5% by volume and 0.5 to 25% by volume, and a gas composition containing a noble gas and ammonia gas in the following order: 75 to 99% by volume and 1 to 25% by volume. Furthermore, it is preferable that oxygen gas is not included in these gas compositions.

[0080] The plasma treatment in Method 2 is carried out in an atmosphere near atmospheric pressure. Near atmospheric pressure is a pressure of 0.1 ± 0.02 MPa. From the viewpoint of controlling plasma generation in the atmosphere and enhancing the action of hydrogen-reducing species, the pressure is preferably between 0.08 and 0.12 MPa, and more preferably between atmospheric pressure (0.101325 MPa) and 0.12 MPa from the viewpoint of shielding from outside air and suppressing the inclusion of components that hinder plasma treatment.

[0081] In the present method 2, the plasma treatment is preferably carried out in an atmosphere shielded from air, particularly oxygen gas, and more preferably in an atmosphere completely shielded from air, from the viewpoint of suppressing the inclusion of components that inhibit the plasma treatment. Methods for shielding from air include raising the ambient pressure in the plasma treatment to above atmospheric pressure, and installing an obstruction wall around the plasma treatment apparatus to suppress the intrusion of air.

[0082] The plasma treatment methods in this Act 2 include a method in which the original molded product is placed and plasma discharge is performed in a plasma chamber filled with a source gas such as a reducing gas to create the desired atmospheric conditions, and a method in which the original molded product is placed between opposing electrodes and plasma discharge is performed while supplying the source gas to create the desired atmospheric conditions. The voltage during plasma discharge is preferably 5 to 20 kV. The power supply frequency during plasma discharge is preferably 50 Hz to 100 MHz. The discharge power density relative to the electrode area during plasma discharge is 1 to 400 W·min / cm². 2 It is preferable that this is the case. When plasma discharge is performed under the above discharge conditions, the modified molded product tends to have excellent adhesion. The discharge time during plasma discharge is preferably between 0.1 seconds and 300 minutes relative to the target molded product.

[0083] The temperature during plasma discharge is preferably between 0 and 300°C, and more preferably between 10 and 50°C. When plasma discharge is performed under these conditions, hydrogen atoms are more easily introduced into the F polymer present on the surface of a molded product containing F polymer in its surface layer. This makes it easier to obtain a modified molded product 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, it is easier to form a more selective and dense modified layer.

[0084] In Method 2 of this Act, the surface of the original molded product may be plasma-treated in an atmosphere that does not contain reducing gases before plasma treatment. By moderately roughening the surface of the original molded product through such treatment, the contact area between the surface of the molded product and the plasma in the plasma treatment of this Act is increased, making it easier to form a modified layer in which hydrogen atoms are more highly introduced. It is preferable that such an atmosphere contains a noble gas.

[0085] If the original molded product is the laminate described above, and it is to be further laminated with other substrates, applying Method 2 to the F layer (2) of the original molded product to form a modified layer before lamination can increase the adhesion strength with other substrates. For example, if a liquid composition containing F polymer powder is applied to a long substrate and heated to form the F layer (2) to prepare the original molded product, then applying Method 2 to the F layer (2) and further laminating it with other long substrates in a roll-to-roll process, a long composite substrate can be easily obtained.

[0086] Furthermore, if the original molded product is a long, roll-shaped laminate, a modified molded product with a modified layer can be obtained by unwinding the original molded product from the roll, passing it between opposing electrodes, and then performing a plasma discharge while supplying a raw material gas to create the desired atmosphere. The resulting modified molded product may be sent directly to the lamination process with other substrates, or it may be wound into a roll, unwound again, and then sent to the lamination process with other substrates. From the viewpoint of simplifying the process, it is preferable to incorporate the plasma discharge device into the lamination apparatus so that the original molded product can be plasma-treated before the lamination process.

[0087] The modified molded article of the present invention (hereinafter also referred to as "the molded article") has a modified layer formed by introducing hydrogen atoms into an F polymer on at least a portion of its surface, wherein the modified layer is a layer in which the maximum height of the H peak is 0.2 times or more the maximum height of the F peak, and the content ratio of fluorine atoms in the said region is 55% or less. The molded article is preferably manufactured by the present method 2.

[0088] The form of the F polymer in the molded article is the same as that in Method 1, including preferred forms. The form of the modified layer and the state or shape of the surface in the molded article are the same as those in Method 2, including preferred forms. Preferred forms of the molded article include a film having a modified layer on at least one surface of an F polymer film, a metal-clad laminate having a metal foil and an F layer (2) formed on at least one surface thereof, with 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 thereof, with a modified layer on the surface of the F layer. When an F layer is formed on both sides of a metal-clad laminate, or when an F layer (2) is formed on both sides of a multilayer film, the modified layer may be present on both surfaces. In these embodiments, the forms of the F polymer film, metal foil, resin film, and F layer (2) are the same as those in the embodiments of this Act 1, including preferred embodiments.

[0089] This molded product possesses both the overall properties of the F polymer and surface properties derived from its 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 a modified layer is preferably 2.0 to 3.5, and more preferably 2.0 to 3.0. The dielectric constant is measured using a split-post dielectric resonator (SPDR) at a frequency of 10 GHz in an environment of 23°C ± 2°C and a relative humidity of 50 ± 5%. If the molded product is a multilayer film, the dielectric constant of the molded product is preferably 2.0 to 3.5, and more preferably 2.0 to 3.0. The water contact angle of the outermost surface (modified layer) of the molded product is preferably 100° or less, and more preferably 90° or less. Furthermore, the water contact angle of the outermost surface (modified layer) of the molded product is preferably 10° or more, and more preferably 30° or more. The water contact angle is the value measured by the static droplet method described in JIS R 3257:1999.

[0090] The surface of this molded product having the modified layer can be further laminated and bonded with other substrates. In this case, the peel strength at the interface between this molded product and the other substrate to be laminated is preferably 8 N / cm or more, and more preferably 10 N / cm or more.

[0091] A method for laminating and bonding this molded product to other substrates is by hot pressing. The temperature for hot pressing is preferably below the melting point of the F polymer, more preferably below 300°C, and even more preferably below 240°C. The temperature for hot pressing is preferably above 120°C, and even more preferably above 160°C. Because this molded product has a modified layer on its surface with excellent physical properties such as wettability, it can be laminated and bonded to other substrates at a lower temperature. Other substrates include, in addition to the metal and resin substrates mentioned above, prepregs, glass substrates, and ceramic substrates.

[0092] The configuration of the laminate of this molded product and other substrates includes a metal substrate / this molded product having modified layers on both sides / other substrate layer / this molded product having modified layers on both sides / metal substrate, a metal substrate layer / other substrate layer / this molded product having modified layers on both sides / other substrate layer / metal substrate layer, etc. Each layer may further contain glass cloth or fillers. Such laminates are useful as antenna components, printed circuit boards, aircraft parts, automobile parts, sports equipment, food industry products, paints, cosmetics, etc. Specifically, they are useful as wire insulation materials (aircraft wires, etc.), electrical insulating tapes, insulating tapes for oil drilling, printed circuit board materials, separation membranes (microfiltration membranes, ultrafiltration membranes, reverse osmosis membranes, ion exchange membranes, dialysis membranes, gas separation membranes, etc.), electrode binders (for lithium secondary batteries, fuel cells, etc.), copy rolls, furniture, automobile dashboards, covers for home appliances, sliding members (load bearings, sliding shafts, valves, bearings, gears, cams, belt conveyors, food transport belts, etc.), tools (shovels, files, drills, saws, etc.), boilers, hoppers, pipes, ovens, baking molds, chutes, dies, toilets, and container coatings.

[0093] Although the present invention has been described above, including the present invention, Method 1 and 2, and the molded product, the present invention is not limited to the configuration of the embodiments described above. For example, the present method, Method 1 and Method 2 may have additional steps in the configuration of the above embodiment, or may be replaced by any steps that produce a similar effect. Furthermore, the molded product may have additional components in the configuration of the above embodiment, or may be replaced by any components that perform a similar function. [Examples]

[0094] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. [Example 1] Production example of modified powder and liquid composition The following ingredients were used. F Powder 1: A powder consisting of Polymer 1 (melting point: 300°C, fluorine content: 71% by mass) containing 97.9 mol% TFE units, 2.0 mol% PPVE units, and 0.1 mol% NAH units (average particle size: 2.6 μm). F Powder 1 corresponds to the resin powder (A) described in paragraph 0154 of International Publication No. 2018 / 016644. F Powder 2: A powder consisting of Polymer 2 (melting point: 300°C, fluorine content: 71% by mass) containing 98.7 mol% TFE units and 1.3 mol% PPVE units (average particle size: 4.3 μm). Polymer 1 contains carbonyl group-containing groups with a main chain of 1 × 10 6 Each molecule has 1000 carbonyl groups, and polymer 2 has carbonyl group-containing groups with a main chain of 1 × 10 6 Each unit has 40 units.

[0095] [Example 1-1] Production example of modified powder 1 and liquid composition 1 F powder 1 was uniformly placed in a plasma chamber equipped with a stage for holding powder, and a mechanism for generating plasma by dielectric barrier discharge, with a dielectric material sandwiched between each of a pair of opposing electrodes. A mixed gas containing 95 volume% Ar gas and 5 volume% hydrogen gas was flowed into the chamber, shielding it from the outside air. During plasma processing, the total concentration of Ar gas and hydrogen gas in the chamber was maintained at 99.9 volume% or higher, the pressure in the chamber was maintained at 0.1 MPa, and the temperature in the chamber was maintained at 25°C. Plasma discharge was induced in the chamber at a processing frequency of 13 kHz and an applied voltage of 9 kV, and F powder 1 was plasma-treated for 1 minute to obtain modified powder 1. 33 parts by mass of modified powder 1 were mixed with 67 parts by mass of distilled water, and the mixture was stirred for 60 minutes to obtain a liquid composition 1 containing modified powder 1 and water, without surfactants, in which the modified powder 1 was dispersed.

[0096] [Example 1-2] Evaluation Examples A mixture consisting of 1 part by mass of a nonionic fluorine-based surfactant (Futergent 250, manufactured by Neos Co., Ltd.) and 66 parts by mass of distilled water was added to 33 parts by mass of F powder 1, and the mixture was stirred for 60 minutes to obtain a liquid composition C1 in which powder 1 was dispersed. This liquid composition C1 corresponds to the dispersion (C-1) described in paragraph 0156 of International Publication No. 2018 / 016644. The "dispersibility" of liquid composition 1 and liquid composition C1 was evaluated as described in the examples of International Publication No. 2018 / 016644, and both liquid compositions showed equivalent dispersibility.

[0097] [Examples 1-3] Production examples of modified powder 2 and liquid composition 2 A modified powder 2 was obtained in the same manner as in Example 1-1, except that F powder 1 was changed to F powder 2, and a liquid composition 2 was obtained. [Examples 1-4] Production examples of modified powder 3 and liquid composition 3 Modified powder 3 was obtained in the same manner as in Example 1-1, except that F powder 1 was changed to F powder 2, and the plasma discharge was performed without particularly shielding the outside air, with the total concentration of Ar gas and hydrogen gas in the chamber during plasma processing being less than 99.9% and the oxygen gas being more than 1 volume%, and so on, in the same manner as in Example 1-1, to obtain modified powder 3 and liquid composition 3.

[0098] [Examples 1-5] Evaluation Examples Liquid composition C2 was prepared in the same manner as in Example 1-2, except that F powder 1 was replaced with F powder 2. The adhesion properties of the molded products were evaluated for each of the liquid compositions 2, 3, and C2 according to the following procedure. Each liquid composition was applied to copper foil by die coating, and the resulting laminate was dried in a 120°C oven for 5 minutes to form a dry film on the copper foil surface. The laminate was then dried in a far-infrared oven at 380°C for 10 minutes to bake the polymer, thereby preparing a laminate with a polymer layer (10 μm thick) formed on the surface of the copper foil. From this laminate, a rectangular test piece measuring 100 mm in length and 10 mm in width was cut out, and the copper foil was peeled off from the polymer layer up to a position 50 mm from one end of the test piece in the longitudinal direction. During the delamination process, the center of the test specimen was set 50 mm from one end in the longitudinal direction. Using a tensile testing machine (manufactured by Orientec Co., Ltd.), the specimen was delaminated at a tensile speed of 50 mm / min at a 90-degree angle, and the average load from a measurement distance of 10 mm to 30 mm was measured to evaluate the delamination strength (N / cm) of the laminate. The peel strength of the laminate formed from liquid composition 2 was 8 N / cm, the peel strength of the laminate formed from liquid composition 3 was 4 N / cm, and the peel strength of the laminate formed from liquid composition C2 was less than 3 N / cm.

[0099] [Example 2] Example of manufacturing modified film The following ingredients were used. Film 1: F polymer 1 film (thickness: 25 μm). Film 2: A film (thickness: 25 μm) of polymer 3 containing 98.2 mol% TFE units and 1.8 mol% PPVE units (melting point: 305°C, fluorine content: 71% by mass). Furthermore, in both Film 1 and Film 2, the film peak H (a peak located at 284 eV to 286 eV in the region from the film surface to a depth of 10 nm) measured by ESCA was weak, the maximum height of peak H was sufficiently smaller than 0.2 times the maximum height of peak F (a peak located at 289 eV to 295 eV in the region from the film surface to a depth of 10 nm), and the fluorine atom content was 60%.

[0100] For surface measurements using ESCA, a Quantera II (ULVAC-PHI) was used. A monochromatic AlKα X-ray source was used at 100W, and a neutralization gun using an ion gun and a barium oxide emitter was employed to prevent charging of the sample surface. The photoelectron detection area was 100 μmφ, the photoelectron detection angle was 45 degrees, and the pass energy was 55 eV. The fluorine atom content was calculated from the various peak intensities (N1s, O1s, C1s, and F1s orbitals) detected during the measurement. The depth from the surface was determined based on the sputtering rate of the SiO2 sputtered film, using C60 ions as the sputtering ion.

[0101] [Example 2-1] Manufacturing example of modified film 1 Film 1 was placed in a plasma chamber equipped with a mechanism capable of generating plasma by dielectric barrier discharge, with a dielectric material sandwiched between each of a pair of opposing electrodes. A mixed gas containing 95 volume% Ar gas and 5 volume% hydrogen gas was flowed into the chamber, shielding it from the outside air, and the pressure inside the chamber was maintained at 0.1 MPa and the temperature inside the chamber at 25°C. Plasma discharge was induced inside the chamber at a processing frequency of 13 kHz and an applied voltage of 9 kV, and film 1 was plasma-treated for 2 minutes.

[0102] On the surface of the obtained film (modified film 1), the maximum height of peak H was 2.5 times the maximum height of peak F, and the fluorine atom content in the region was 30%. Furthermore, when the surface of modified film 1 was etched 100 nm in the thickness direction and measured again by ESCA, the profile was equivalent to that of film 1, confirming that modified film 1 is a film having a modified layer formed by introducing hydrogen atoms into polymer 1 on its surface.

[0103] [Example 2-2] Manufacturing example of modified film 2 The film 1 was plasma-treated in the same manner as in Example 1, except that the gas sealed in the chamber was changed to a mixed gas containing 94 volume% Ar gas, 5 volume% ammonia gas, and 1 volume% water vapor. On the surface of the obtained film (modified film 2), the maximum height of peak H was 0.2 times the maximum height of peak F, confirming that modified film 2 is a film having a modified layer formed on its surface by introducing hydrogen atoms into polymer 1.

[0104] [Example 2-3] Manufacturing example of modified film 3 The process was the same as in Example 1, except that film 1 was replaced with film 2, and film 2 was plasma-treated. On the surface of the obtained film (modified film 3), the maximum height of peak H was three times the maximum height of peak F, and the fluorine atom content in the region was 25%, confirming that the modified film 3 is a film having a modified layer on its surface formed by introducing hydrogen atoms into polymer 2.

[0105] [Example 2-4] Manufacturing example of modified film 4 (comparative example) The film 1 was plasma-treated in the same manner as in Example 1, except that only Ar gas was used to seal the chamber. The surface condition of the obtained film (modified film 4), as measured by ESCA, was almost identical to that of film 1.

[0106] [Example 2-5] Manufacturing example of modified film 5 (comparative example) Film 1 was plasma-treated in the same manner as in Example 1, except that it was under vacuum conditions. The surface condition of the obtained film (modified film 5), as measured by ESCA, was almost identical to that of film 1.

[0107] [Example 2-6] Evaluation example of modified film A modified film 1 and a plain copper foil were placed opposite each other and hot-pressed (temperature: 340°C, pressure: 15kN / m) to obtain an adhesive laminate of modified film 1 and copper foil. From this adhesive laminate, a rectangular test piece measuring 100 mm in length and 10 mm in width was cut out and left to stand at 25°C for 3 months. Next, the copper foil layer was peeled off from the modified film 1 layer to a position 50 mm from one end of the test piece in the longitudinal direction. For peeling, the center was set at a position 50 mm from one end of the test piece in the longitudinal direction, and a tensile testing machine (manufactured by Orientec Co., Ltd.) was used to peel the piece at a tensile speed of 50 mm / min at a 90-degree angle. The average load from a measurement distance of 10 mm to 30 mm was measured and defined as the peel strength (N / cm). For each film, adhesive laminates were similarly prepared, and their peel strength was evaluated. The results are summarized in Table 1.

[0108] [Table 1] [Industrial applicability]

[0109] As is clear from the results above, the modified powder produced by this method is less prone to sedimentation, and its dispersibility in water is equivalent to that when a surfactant is added, even without the addition of a surfactant. Furthermore, molded articles formed from a liquid composition containing the modified powder produced by this method exhibit higher adhesion to the substrate and superior bonding properties compared to molded articles formed from a liquid composition containing the original powder. From the above, it can be seen that the modified powder produced by this method is highly surface-modified, and that the composition containing this modified powder becomes a liquid composition with excellent liquid properties such as dispersibility even without the addition of a surfactant, and can form molded products with high adhesion to the substrate. The liquid composition containing the modified powder produced by this method is a liquid composition with excellent liquid properties such as dispersibility, and can be efficiently impregnated into porous or fibrous materials.

[0110] Furthermore, as is clear from the results above, when modified films 1 to 3, which are modified molded products created by this method, are bonded to copper foil, the peel strength is higher than that of the original molded product, film 1 or 2, and copper foil, indicating that the adhesion strength has been improved. Also, compared to the peel strength of modified films 4 and 5, which are created without this method, and copper foil, the peel strength of modified films 1 to 3 produced by this method and copper foil is higher. From the above, it can be seen that the modified molded products produced by this method have a high degree of surface modification. Therefore, laminates of modified molded products produced by this method and other substrates are considered useful for applications such as antenna components, printed circuit boards, aircraft parts, automobile parts, sports equipment, food industry products, paints, and cosmetics.

Claims

1. A method for producing a modified tetrafluoroethylene polymer, comprising plasma treatment of a tetrafluoroethylene polymer in an atmosphere near atmospheric pressure to obtain a modified tetrafluoroethylene polymer.

2. A method for producing modified powder, comprising plasma treatment of a tetrafluoroethylene polymer powder in an atmosphere near atmospheric pressure to modify the surface of the powder.

3. The manufacturing method according to claim 2, wherein the powder is plasma-treated in an atmosphere near 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 according to any one of claims 2 or 3, wherein the plasma treatment is performed in an atmosphere that shields the air.

5. The manufacturing method according to any one of claims 2 to 4, wherein the powder is subjected to plasma treatment in an atmosphere containing a noble gas before the plasma treatment is performed.

6. The manufacturing method according to any one of claims 2 to 5, wherein the atmosphere comprises at least one gas, a reducing gas having hydrogen atoms, a vinyl compound, and a vinylidene compound.

7. The manufacturing method according to any one of claims 2 to 6, wherein the tetrafluoroethylene polymer is a tetrafluoroethylene polymer having a fluorine content of 70 to 76% by mass.

8. The manufacturing method according to any one of claims 2 to 7, wherein the tetrafluoroethylene polymer has an atomic group containing oxygen atoms.

9. A liquid composition comprising a modified powder obtained by a manufacturing method according to any one of claims 2 to 8, and a liquid dispersion medium, wherein the modified powder is dispersed.

10. A method for producing a modified molded article having a modified layer formed by introducing hydrogen atoms into the tetrafluoroethylene polymer on at least a portion of the surface of the molded article having a surface layer containing a tetrafluoroethylene polymer, wherein the surface layer of the molded article having at least a portion of the surface layer is plasma-treated in an atmosphere near atmospheric pressure containing a reducing gas having hydrogen atoms.

11. The manufacturing method according to claim 10, wherein the plasma treatment is performed in an atmosphere that shields the air.

12. The manufacturing method according to claim 10 or 11, wherein the surface layer is subjected to plasma treatment in an atmosphere that does not contain reducing gas before the plasma treatment is performed.

13. The manufacturing method according to claim 12, wherein the reducing gas is hydrogen gas, ammonia gas, or hydrocarbon gas.

14. The manufacturing method according to any one of claims 10 to 13, wherein the tetrafluoroethylene polymer has an atomic group containing oxygen atoms.

15. A modified molded article containing a tetrafluoroethylene polymer, having a modified layer formed by introducing hydrogen atoms into a tetrafluoroethylene polymer on at least a portion of its surface, wherein the modified layer has a maximum peak height at 284 eV to 286 eV in a region from the surface to a depth of 1 nm, as measured by X-ray photoelectron spectroscopy, that is 0.2 times or more than the maximum peak height at 289 eV to 295 eV in the same region, and the fluorine atom content in the same region is 55% or less.

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