Molded body and method for producing molded body

Abstract

Provided is a molded body containing a fluorine-containing polymer including a constituent unit based on a monomer having a C-H bond. The molded body is amorphous, and, in the molded body, the proportion of C-F bonds to C-H bonds in a region up to 1 μm from the surface in the thickness direction is larger than the proportion of C-F bonds to C-H bonds in the molded body as a whole. Also provided are applications for the molded body.

Description

Molded article and method for manufacturing a molded article

[0001] This disclosure relates to molded articles and methods for manufacturing molded articles.

[0002] Fluorine-containing polymers are used in a wide variety of fields due to their excellent heat resistance, chemical resistance, oil resistance, weather resistance, and electrical insulation properties.

[0003] For example, Non-Patent Documents 1 and 2 describe a method for fluorinating the surface of a polymer using gaseous fluorine.

[0004] Kharitonov, A. P. et al., Pure Appl. Chem. , 2009, 81, 451 Journal of Polymer Science Part A: Polymer Chemistry, Vol. 49, 1517-1527 (2011)

[0005] Generally, polytetrafluoroethylene (hereinafter also referred to as "PTFE") has excellent surface properties such as water repellency, oil repellency, chemical resistance, weather resistance, non-stick properties, and low friction, but it has poor moldability.

[0006] In fluorine-containing polymers, there is a need to achieve both good surface properties and moldability.

[0007] One embodiment of this disclosure aims to provide a molded article with excellent surface properties and moldability, and a method for manufacturing the molded article.

[0008] Means for solving the above problems include the following embodiments: <1> A molded article containing a fluorine-containing polymer that includes constituent units based on monomers having C-H bonds, wherein the ratio of C-F bonds to C-H bonds in a region from the surface to 1 μm in the thickness direction is greater than the ratio of C-F bonds to C-H bonds in the entire molded article, and the molded article is amorphous. <2> The molded article according to <1>, wherein the monomer having C-H bonds is at least one selected from the group consisting of ethylene, vinyl fluoride, trifluoroethylene, 1,2-difluoroethylene, and vinylidene fluoride. <3> The molded article according to <1> or <2>, wherein the fluorine-containing polymer includes constituent units based on ethylene and constituent units based on tetrafluoroethylene. <4> The molded article according to any one of <1> to <3>, wherein, as measured by X-ray photoelectron spectroscopy, the content ratio of element F to element C on the surface of the molded article is 1.3 or more. <5> When the surface of the molded body was measured using the total internal reflection method, the wavenumber was 1200 cm. －１ Wavenumber 1453 cm⁻¹ for absorption peak intensity －１ A molded article according to any one of <1> to <4>, wherein the ratio of absorption peak intensities is 0.7 or less. <6> A method for producing a molded article, comprising fluorinating an untreated molded article containing a fluorine-containing polymer that includes constituent units based on monomers having C-H bonds in a liquid, thereby converting C-H bonds to C-F bonds in a region extending at least 1 μm from the surface in the thickness direction. <7> A method for producing a molded article according to <6>, wherein the monomer having C-H bonds is at least one selected from the group consisting of ethylene, vinyl fluoride, trifluoroethylene, 1,2-difluoroethylene, and vinylidene fluoride. <8> A method for producing a molded article according to <6> or <7>, wherein the fluorine-containing polymer includes constituent units based on ethylene and constituent units based on tetrafluoroethylene. <9> A method for producing a molded article according to any one of <6> to <8>, wherein the fluorination in liquid is carried out by introducing fluorine gas in the presence of a fluorine-containing solvent and an aromatic hydrocarbon solvent.

[0009] According to one embodiment of the present disclosure, a molded article having excellent surface properties and moldability, and a method for manufacturing the molded article are provided.

[0010] Figure 1 shows the results of the ATR method. Figure 2 shows the results of the transmission method. Figure 3 shows the measurement results by SAXS. Figure 4 shows the measurement results by WAXD. Figure 5 shows the results of the ATR method. Figure 6 shows the results of the transmission method.

[0011] The embodiments of this disclosure will be described in detail below. However, the embodiments of this disclosure are not limited to the embodiments described below. In the embodiments described below, the components (including elemental steps, etc.) are not essential unless otherwise specified. The same applies to numerical values ​​and their ranges, and do not limit the embodiments of this disclosure.

[0012] In this disclosure, numerical ranges indicated using "~" include the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced by the upper or lower limit of another numerical range described in stages. In this disclosure, each component may contain multiple types of the corresponding substance. If multiple types of the substance corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple types of substances present in the composition, unless otherwise specified.

[0013] [Molded Article] The molded article of the present disclosure is a molded article containing a fluorine-containing polymer that includes constituent units based on monomers having C-H bonds, wherein the ratio of C-F bonds to C-H bonds in a region from the surface to 1 μm in the thickness direction is greater than the ratio of C-F bonds to C-H bonds in the entire molded article, and the article is amorphous.

[0014] The molded articles of this disclosure exhibit excellent surface properties and moldability. In the molded articles of this disclosure, the ratio of C-F bonds to C-H bonds in the region from the surface to 1 μm in the thickness direction is greater than the ratio of C-F bonds to C-H bonds in the entire molded article, thus exhibiting excellent surface properties similar to PTFE molded articles. Furthermore, the molded articles are amorphous and, unlike PTFE molded articles, exhibit excellent moldability. Conventionally, it has been difficult to achieve both excellent surface properties and moldability. For example, Non-Patent Documents 1 and 2 describe a method of fluorinating the surface of a polymer using gaseous fluorine, but in this method, the polymer on the fluorinated surface crystallizes.

[0015] <Fluorine-containing polymer> The molded articles of this disclosure contain a fluorine-containing polymer that includes constituent units based on monomers having C-H bonds.

[0016] A monomer having a C-H bond is not particularly limited as long as it has a C-H bond and is a polymerizable compound. From the viewpoint of versatility, a monomer having a C-H bond is preferably one with 2 to 4 carbon atoms, and more preferably one with 2 carbon atoms. Specifically, examples of monomers with 2 carbon atoms include ethylene, a monomer with 3 carbon atoms includes propene, and examples of monomers with 4 carbon atoms include 1-butene, 2-butene, and 1,3-butadiene. Furthermore, it is also preferable for a monomer having a C-H bond to be a monomer that has both a C-H bond and a C-F bond.

[0017] Examples of monomers having a C-H bond include ethylene, vinyl fluoride, trifluoroethylene, 1,2-difluoroethylene, vinylidene fluoride, propylene, α-butylene, β-butylene, and isobutylene.

[0018] In particular, from the viewpoint of surface properties, the monomer having a C-H bond is preferably at least one selected from the group consisting of ethylene, vinyl fluoride, trifluoroethylene, 1,2-difluoroethylene, and vinylidene fluoride.

[0019] Specifically, from the viewpoint of moldability, it is preferable that the fluorine-containing polymer includes structural units based on ethylene and structural units based on tetrafluoroethylene.

[0020] If the fluorine-containing polymer contains ethylene-based structural units and tetrafluoroethylene-based structural units, it may also contain other structural units.

[0021] Furthermore, it is preferable that the molded article of this disclosure is a molded article produced by fluorinating an untreated molded article containing a fluorine-containing polymer that includes constituent units based on monomers having C-H bonds in a liquid state, as described later. Therefore, if the fluorine-containing polymer contained in the untreated molded article includes constituent units based on ethylene and constituent units based on tetrafluoroethylene, it is preferable that the molded article of this disclosure contains a fluorine-containing polymer that includes constituent units based on ethylene and constituent units based on tetrafluoroethylene, while also containing a fluorine-containing polymer in which the C-H bonds in each constituent unit have been converted to C-F bonds.

[0022] When a fluorinated polymer contains ethylene-based structural units and tetrafluoroethylene-based structural units, the ratio of fluorine (F) to carbon (C) on the surface of the molded article is preferably 1.3 or higher, more preferably 1.5 or higher, and even more preferably 1.8 or higher, as measured by X-ray photoelectron spectroscopy (XPS). For example, the ratio of fluorine (F) to carbon (C) on the surface of the molded article is 2.2 or lower. Theoretically, the upper limit is 2.0, but the measured value may be 2.2.

[0023] Furthermore, from the viewpoint of versatility, the fluorine-containing polymer preferably contains structural units based on vinylidene fluoride, vinyl fluoride, trifluoroethylene, etc., and is particularly preferably containing structural units based on vinylidene fluoride. The fluorine-containing polymer may also contain other structural units. The molded article of this disclosure is preferably a molded article produced by fluorinating an untreated molded article containing a fluorine-containing polymer containing structural units based on monomers having C-H bonds in a liquid state, as will be described later. Therefore, if the fluorine-containing polymer contained in the untreated molded article contains structural units based on vinylidene fluoride, the molded article of this disclosure preferably contains a fluorine-containing polymer that includes structural units based on vinylidene fluoride, while the C-H bonds in each structural unit are converted to C-F bonds. When a fluorine-containing polymer contains constituent units based on vinylidene fluoride, the ratio of element F to element C on the surface of the molded article, as measured by X-ray photoelectron spectroscopy (XPS), is preferably 1.3 or higher, more preferably 1.5 or higher, and even more preferably 1.7 or higher. For example, the ratio of element F to element C on the surface of the molded article is 2.2 or less. Theoretically, the upper limit is 2.0, but the measured value may be 2.2.

[0024] When the content ratio of element F to element C on the surface of the molded product is 1.3 or higher, surface properties such as water repellency, oil repellency, and chemical resistance are further improved.

[0025] X-ray photoelectron spectroscopy (XPS) measurements are performed under the following conditions, for example: X-ray type: Mg; Kα-ray acceleration voltage: 10 kV; Sample current: 15 mA; Photoelectron emission angle: 90 degrees

[0026] In the molded article of this disclosure, the ratio of C-F bonds to C-H bonds in the region from the surface to 1 μm in the thickness direction is greater than the ratio of C-F bonds to C-H bonds in the entire molded article. Therefore, the molded article of this disclosure has excellent surface properties such as water repellency, oil repellency, and chemical resistance.

[0027] In the region from the surface to a depth of 1 μm in the thickness direction, the ratio of C-F bonds to C-H bonds is greater than the ratio of C-F bonds to C-H bonds in the entire molded body. This can be confirmed by performing measurements on the molded body using Fourier transform infrared spectroscopy (FT-IR) by both the total reflection measurement method (ATR method) and the transmission method.

[0028] In the measurement by the ATR method, an absorption spectrum in the region from the surface to a depth of about 1 μm in the thickness direction can be obtained. On the other hand, in the measurement by the transmission method, an absorption spectrum of the entire molded body can be obtained. By comparing the absorption spectrum obtained by the ATR method with the absorption spectrum obtained by the transmission method, the relative amount of the ratio of C-F bonds to C-H bonds is determined.

[0029] In the absorption spectrum, for example, at a wave number of 1453 cm －１ an absorption peak of -CH ２ CH ２ - derived from a structural unit based on ethylene (-CH ２ -) can be confirmed. Also, at a wave number of 1200 cm －１ an absorption peak of -CF ２ CF ２ - derived from a structural unit based on tetrafluoroethylene (-CF ２ -) can be confirmed. Based on the absorption peak intensity (i.e., absorbance) at a wave number of 1453 cm －１ and the absorption peak intensity at 1200 cm －１ the ratio of C-F bonds to C-H bonds can be calculated.

[0030] When the surface of the molded body is measured by the total reflection measurement method (ATR method), the ratio of the absorption peak intensity at a wave number of 1453 cm －１ to the absorption peak intensity at a wave number of 1200 cm －１ is preferably 0.7 or less, more preferably 0.5 or less, even more preferably 0.4 or less, particularly preferably 0.3 or less, and most preferably 0.25 or less. The lower limit value of the above ratio is, for example, 0. <…>[[ID=3%]]

[0031] When the above ratio is 0.7 or less, surface properties such as water repellency, oil repellency, and chemical resistance are further improved.

[0032] The molded articles of this disclosure are amorphous. Whether or not a molded article is amorphous can be confirmed by performing a measurement using wide-angle X-ray diffraction (WAXD). If the molded article has a crystalline structure, a peak originating from the crystalline structure will be confirmed in the measurement using wide-angle X-ray diffraction (WAXD). Therefore, if no peak is confirmed in the measurement using wide-angle X-ray diffraction (WAXD), the molded article is determined to be amorphous.

[0033] As described above, in the molded article of this disclosure, the ratio of C-F bonds to C-H bonds in the region from the surface to 1 μm in the thickness direction is greater than the ratio of C-F bonds to C-H bonds in the entire molded article. The fact that crystallization does not occur in the region near the surface despite the high ratio of C-F bonds is unique compared to conventional molded articles.

[0034] The form of the molded articles of this disclosure is not particularly limited and includes, for example, films, tubes, hoses, tanks, seals, and wires.

[0035] When the molded article of this disclosure is a film, it is preferable that the ratio of C-F bonds to C-H bonds in a region extending from at least one main surface of the film in the thickness direction up to 1 μm is greater than the ratio of C-F bonds to C-H bonds in the entire molded article. In this disclosure, the main surfaces of the film refer to a pair of surfaces of the film that have a relatively large area.

[0036] When the molded article of this disclosure is a tube, it is preferable that the ratio of C-F bonds to C-H bonds in a region up to 1 μm in the thickness direction of at least one of the outer and inner surfaces of the tube is greater than the ratio of C-F bonds to C-H bonds in the entire molded article.

[0037] [Method for Manufacturing a Molded Article] The method for manufacturing a molded article according to the present disclosure includes fluorinating an untreated molded article containing a fluorine-containing polymer that includes constituent units based on monomers having C-H bonds in a liquid, thereby converting C-H bonds to C-F bonds in a region extending from the surface in the thickness direction to at least 1 μm.

[0038] According to the method for manufacturing a molded article of this disclosure, an untreated molded article is fluorinated to produce the molded article of this disclosure.

[0039] In this disclosure, "untreated molded article" means a molded article before fluorination in liquid. An untreated molded article can be produced by molding a fluorine-containing polymer, which is the raw material, by a method that is generally known. The molding method is not particularly limited. The untreated molded article may be a commercially available product.

[0040] Examples of fluorine-containing polymers contained in untreated molded articles that have C-H bonds include ethylene, vinyl fluoride, trifluoroethylene, 1,2-difluoroethylene, vinylidene fluoride, propylene, α-butylene, β-butylene, and isobutylene.

[0041] In particular, from the viewpoint of surface properties, the monomer having a C-H bond is preferably at least one selected from the group consisting of ethylene, vinyl fluoride, trifluoroethylene, 1,2-difluoroethylene, and vinylidene fluoride.

[0042] Specifically, from the viewpoint of moldability, it is preferable that the fluorine-containing polymer contained in the untreated molded article contains ethylene-based structural units and tetrafluoroethylene-based structural units.

[0043] In the fluorine-containing polymer contained in the untreated molded article, the content ratio of each constituent unit is not particularly limited and can be adjusted as appropriate to the desired properties. For example, if the fluorine-containing polymer contained in the untreated molded article contains ethylene-based constituent units and tetrafluoroethylene-based constituent units, the content of ethylene-based constituent units is preferably 30 to 70% by mass, more preferably 40 to 60% by mass, and even more preferably 45 to 55% by mass, based on the total amount of the fluorine-containing polymer. Similarly, the content of tetrafluoroethylene-based constituent units is preferably 30 to 70% by mass, more preferably 40 to 60% by mass, and even more preferably 45 to 55% by mass, based on the total amount of the fluorine-containing polymer.

[0044] Furthermore, from the viewpoint of versatility, the fluorine-containing polymer contained in the untreated molded article preferably contains constituent units based on vinylidene fluoride, vinyl fluoride, trifluoroethylene, etc., with vinylidene fluoride being particularly preferred. In the fluorine-containing polymer contained in the untreated molded article, the content ratio of each constituent unit is not particularly limited and can be adjusted as appropriate according to the desired properties. For example, when the fluorine-containing polymer contained in the untreated molded article contains constituent units based on vinylidene fluoride, the content of constituent units based on vinylidene fluoride is preferably 30 to 100% by mass, more preferably 50 to 100% by mass, and even more preferably 70 to 100% by mass, relative to the total amount of the fluorine-containing polymer.

[0045] One method for performing fluorination in a liquid is to immerse an untreated molded body in a liquid medium and then introduce fluorine gas into the liquid medium containing the immersed untreated molded body.

[0046] The liquid medium is not particularly limited, but a solvent that does not fluorinate is preferred when fluorination is performed, and specifically, a fluorine-containing solvent is preferred. Examples of fluorine-containing solvents include fluorine-containing alkanes, fluorine-containing aromatic compounds, fluoroalkyl ethers, fluorine-containing alkylamines, and fluoroalcohols.

[0047] Fluorine gas may be diluted with an inert gas and introduced as a mixed gas. Examples of inert gases include nitrogen gas and argon gas. The fluorine gas content in the mixed gas is preferably 3 to 70% by volume, and more preferably 10 to 30% by volume.

[0048] From the viewpoint of increasing the conversion rate from C-H bonds to C-F bonds, fluorination in liquid is preferably carried out by introducing fluorine gas in the presence of a fluorine-containing solvent and an aromatic hydrocarbon solvent.

[0049] Examples of aromatic hydrocarbon solvents include benzene, toluene, xylene, ethylbenzene, and naphthalene.

[0050] In fluorination in liquid, the liquid temperature is not particularly limited, but from the viewpoint of increasing the conversion rate from C-H bonds to C-F bonds, it is preferable to carry it out at -10 to 80°C, and more preferably at 20 to 50°C.

[0051] Next, embodiments of the present disclosure will be specifically described with reference to examples, but the embodiments of the present disclosure are not limited to these examples. Note that ETFE means a copolymer containing ethylene-based structural units and tetrafluoroethylene-based structural units.

[0052] [Example 1] A 15mm x 15mm ETFE film (Fluon® ETFE, manufactured by AGC, 25μm thick) is subjected to CLCF in a 500mL autoclave. ２ CFClCF ２ OCF ２ CF ２ The ETFE film was immersed in 640 g of Cl (hereinafter referred to as "CFE-419"). The solution in which the ETFE film was immersed was stirred at 25°C, and nitrogen gas was blown in for 1 hour. Then, a mixture of nitrogen gas and fluorine gas (nitrogen gas:fluorine gas = 80:20 (volume ratio)) was blown in at a flow rate of 0.10 L / min for 1 hour. Next, the solution in which the ETFE film was immersed was heated to 40°C, and while blowing in the above mixture gas at a flow rate of 0.10 L / min, 4 mL of benzene-CFE-419 solution (benzene concentration: 0.4 mass%) was injected over 15 minutes. Next, the injection of benzene-CFE-419 solution was stopped, and the above mixture gas was blown in at a flow rate of 0.10 L / min for 15 minutes. Furthermore, while blowing the above mixed gas at a flow rate of 0.10 L / min, 2 mL of benzene CFE-419 solution (benzene concentration: 0.4 mass%) was injected over 8 minutes. Then, the injection of benzene CFE-419 solution was stopped, and the above mixed gas was blown in at a flow rate of 0.10 L / min for 15 minutes. This operation A was repeated four times. After that, the solution in which the ETFE film was immersed was cooled to 25°C. Nitrogen gas was blown in for 2 hours, and the resulting film was vacuum dried to obtain a fluorinated ETFE film. The mass increase rate was 10 mass%.

[0053] [Example 2] Similar to Example 1, the procedure was carried out up to the point of "repeating operation A four times". In Example 2, the above mixed gas was further blown in at a flow rate of 0.10 L / min for 3 hours. After that, the liquid in which the ETFE film was immersed was cooled to 25°C. Nitrogen gas was blown in for 2 hours, and the resulting film was vacuum dried to obtain a fluorinated ETFE film. The mass increase rate was 13% by mass.

[0054] [Example 3] Similar to Example 1, an ETFE film was immersed in CFE-419. The immersion solution of the ETFE film was stirred at 25°C, and nitrogen gas was blown in for 1 hour. Then, a mixed gas of nitrogen gas and fluorine gas (nitrogen gas:fluorine gas = 80:20 (volume ratio)) was blown in at a flow rate of 0.10 L / min for 1 hour. Next, the immersion solution of the ETFE film was heated to 40°C, and while blowing in the mixed gas at a flow rate of 0.10 L / min, 60 mL of benzene-CFE-419 solution (benzene concentration: 0.4 mass%) was injected over 4 hours. Next, the injection of the benzene-CFE-419 solution was stopped, and the mixed gas was blown in at a flow rate of 0.10 L / min for 1 hour. After that, the immersion solution of the ETFE film was cooled to 25°C. Nitrogen gas was blown in for 2 hours, and the resulting film was vacuum dried to obtain a fluorinated ETFE film. The mass increase rate was 14% by mass.

[0055] [Example 4] The process from immersing the ETFE film in CFE-419 to vacuum-drying the resulting film was repeated twice to obtain a fluorinated ETFE film. The mass increase rate was 22% by mass.

[0056] [Example 5] The process from immersing the ETFE film in CFE-419 to vacuum-drying the resulting film was repeated four times to obtain a fluorinated ETFE film. The mass increase rate was 26% by mass.

[0057] <XPS Measurement> X-ray photoelectron spectroscopy (XPS) measurements were performed on the films obtained in Examples 1 to 5, the ETFE film before fluorination, and the PTFE film (NAFRON® PTFE tape (TOMBO No. 9001), manufactured by Nichias Corporation).

[0058] The measurement equipment and conditions are as follows: Measurement equipment: JPS-9010MC (manufactured by JEOL Ltd.) X-ray type: Mg Kα-rays Acceleration voltage: 10kV Sample current: 15mA Photoelectron emission angle: 90 degrees

[0059] The ratio of fluorine (F / C) to carbon (C) on the film surface (several nm) was calculated from the ratio of peak areas originating from the carbon 1s orbital and the fluorine 1s orbital. The results are shown in Table 1.

[0060]

[0061] Table 1 shows that films with a larger mass increase rate exhibit a larger F / C value. In Examples 4 and 5, the F / C was equivalent to that of PTFE films.

[0062] <FT-IR Measurement> Fourier transform infrared spectroscopy (FT-IR) measurements were performed on the films of Examples 1 to 5, and on the ETFE film before fluorination. A Shimadzu IRSpirit measuring device was used. Measurements were performed using total internal reflection (ATR) and transmission methods with a diamond prism, with a resolution of 4 cm. －１ The experiment was conducted under the condition that the cumulative number of trials was 20.

[0063] Figure 1 shows the results of the ATR method. Figure 2 shows the results of the transmission method.

[0064] In all measurement methods, the wavenumber was 1453 cm⁻¹. －１ In this context, the constituent units based on ethylene (-CH ２ CH ２ -) derived from -CH ２ - Absorption peak was observed, wavenumber 1200 cm. －１ In this context, the constituent units based on tetrafluoroethylene (-CF ２ CF ２ -) derived from -CF ２ - An absorption peak was confirmed.

[0065] By quantifying the absorbance at these wavenumbers, the ATR method allows for the calculation of the proportion of ethylene-based constituent units in the region from the surface to approximately 1 μm in the thickness direction. The transmission method, on the other hand, allows for the calculation of the proportion of ethylene-based constituent units throughout the entire film.

[0066] The proportion of ethylene-based constituent units was calculated using the following formula: Proportion of ethylene-based constituent units = [I(1453)] / [I(1200)] I(1453): 1453 cm⁻¹ in the FT-IR spectrum of the film －１ Absorbance I (1200): 1200 cm⁻¹ in the FT-IR spectrum of the film －１ absorbance

[0067] Table 2 shows the "percentage of ethylene-based constituent units" calculated using the ATR method.

[0068]

[0069] Table 2 shows that in films Examples 1 to 5, the proportion of ethylene-based constituent units is significantly reduced compared to the ETFE film. Furthermore, Figures 1 and 2 show that in films Examples 1 to 5, the ratio of C-F bonds to C-H bonds in the region from the surface to 1 μm in the thickness direction is greater than the ratio of C-F bonds to C-H bonds in the entire film.

[0070] <SAXS Measurement> Small-angle X-ray scattering (SAXS) measurements were performed on the films of Examples 1 to 5, the ETFE film before fluorination, and the PTFE film (NAFRON® PTFE tape (TOMBO No. 9001), manufactured by Nichias Corporation). The measurement device used was BL40B2 at SPring-8. The X-ray wavelength was set to 0.1 nm and the camera length to 4196 mm.

[0071] Figure 3 shows the measurement results obtained using SAXS.

[0072] As shown in Figure 3, it was found that the films in Examples 1 to 5 retained the scattering patterns observed in ETFE films.

[0073] <WAXD Measurement> Wide-angle X-ray diffraction (WAXD) measurements were performed on the films of Examples 1 to 5, the ETFE film before fluorination, and the PTFE film (NAFRON® PTFE tape (TOMBO No. 9001), manufactured by Nichias Corporation). The measurement device used was BL40B2 at Spring-8. The X-ray wavelength was set to 0.071 nm and the camera length to 93.35 mm.

[0074] Figure 4 shows the measurement results obtained using WAXD.

[0075] As shown in Figure 4, it was found that the films in Examples 1 to 5 retained the structure of the ETFE film. Furthermore, no peaks originating from the crystalline structure of the PTFE film were observed in the films in Examples 1 to 5. Therefore, it was found that the films in Examples 1 to 5 are amorphous.

[0076] <Contact Angle Measurement> Contact angles were measured for the films of Examples 1 to 5, the ETFE film before fluorination, and the PTFE film (NAFRON® PTFE tape (TOMBO No. 9001), manufactured by Nichias Corporation). A DMo-502 manufactured by Kyowa Interface Science Co., Ltd. was used as the measuring device. Water, diiodomethane, and n-hexadecane were used as the liquids for measurement. In the measurements using water and diiodomethane, 1 μL droplets were placed at five different locations on each film. The average of the obtained measurements was calculated. In the measurements using n-hexadecane, 5 μL droplets were placed at three different locations on each film. The average of the obtained measurements was calculated. From the contact angle values ​​of water and diiodomethane, the surface free energy of the film was calculated using the Owens-Wendt equation. Table 3 shows the contact angles and surface free energies for water, diiodomethane, and n-hexadecane.

[0077]

[0078] Table 3 shows that the films in Examples 1 to 5 exhibit excellent surface properties.

[0079] [Example 6] A fluorinated PVDF film was obtained using the same method as in Example 3, except that a 15 mm x 15 mm PVDF film (PVDF Piezo Film Sheet (uniaxial orientation, polarization only), manufactured by Waki ​​Research Institute, 28 μm thick) was used instead of ETFE film. The mass increase rate was 3% by mass.

[0080] <XPS Measurement> X-ray photoelectron spectroscopy (XPS) measurements were performed on the film obtained in Example 6, the PVDF film before fluorination, and the PTFE film (NAFRON® PTFE tape (TOMBO No. 9001), manufactured by Nichias Corporation).

[0081] The ratio of fluorine (F / C) to carbon (C) on the film surface (several nm) was calculated from the ratio of peak areas originating from the carbon 1s orbital and the fluorine 1s orbital. The results are shown in Table 4.

[0082]

[0083] <FT-IR Measurement> Fourier transform infrared spectroscopy (FT-IR) measurements were performed on the film of Example 6 and the PVDF film before fluorination using the same method as in Example 1. The measurements were performed using total internal reflection (ATR) and transmission methods with a diamond prism, and in the ATR method, measurements were performed parallel to the orientation direction.

[0084] Figure 5 shows the results of the ATR method. Figure 6 shows the results of the transmission method.

[0085] In the ATR method, wavenumber 1403 cm⁻¹ －１ In this context, the constituent unit based on methylene (-CH ２ -) derived from -CH ２ - An absorption peak was confirmed.

[0086] By quantifying the absorbance at this wavenumber, the ATR method allows for the calculation of the proportion of methylene-based constituent units in the region from the surface to approximately 1 μm in the thickness direction.

[0087] The proportion of constituent units based on methylene was calculated using the following formula: Proportion of constituent units based on methylene = [I(1403)] / [I(1200)] I(1403): 1403 cm in the FT-IR spectrum of the film －１ Absorbance I (1200): 1200 cm⁻¹ in the FT-IR spectrum of the film －１ absorbance

[0088] Table 5 shows the "proportion of methylene-based constituent units" calculated using the ATR method.

[0089]

[0090] Table 5 shows that in the film of Example 6, the proportion of methylene-based structural units is significantly reduced compared to the PVDF film. Furthermore, Figures 5 and 6 show that in the film of Example 6, the ratio of C-F bonds to C-H bonds in the region from the surface to 1 μm in the thickness direction is greater than the ratio of C-F bonds to C-H bonds in the entire film.

[0091] <Contact Angle Measurement> The contact angle was measured for the film of Example 6 and the PVDF film before fluorination. For each film, the contact angle was measured on a plane parallel to the orientation direction and on a plane perpendicular to it. A DMo-502 manufactured by Kyowa Interface Science Co., Ltd. was used as the measuring device. Water, diiodomethane, and n-hexadecane were used as the liquids for measurement. In the measurements using water and diiodomethane, 1 μL droplets were placed at five different locations on each film. The average of the obtained measurements was calculated. In the measurements using n-hexadecane, 5 μL droplets were placed at three different locations on each film. The average of the obtained measurements was calculated. From the contact angle values ​​of water and diiodomethane, the surface free energy of the film was calculated using the Owens-Wendt equation. Table 6 shows the results for the contact angle and surface free energy of water, diiodomethane, and n-hexadecane.

[0092]

[0093] Table 6 shows that the film in Example 6 exhibits excellent surface properties.

[0094] Furthermore, the disclosure of Japanese Patent Application No. 2025-008078, filed on January 20, 2025, is incorporated herein by reference in its entirety. In addition, all documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard had been specifically and individually indicated as being incorporated by reference.

Claims

1. A molded article containing a fluorine-containing polymer comprising constituent units based on monomers having C-H bonds, wherein the ratio of C-F bonds to C-H bonds in a region from the surface to 1 μm in the thickness direction is greater than the ratio of C-F bonds to C-H bonds in the entire molded article, and the molded article is amorphous.

2. The molded article according to claim 1, wherein the monomer having a C-H bond is at least one selected from the group consisting of ethylene, vinyl fluoride, trifluoroethylene, 1,2-difluoroethylene, and vinylidene fluoride.

3. The molded article according to claim 1 or claim 2, wherein the fluorine-containing polymer comprises a structural unit based on ethylene and a structural unit based on tetrafluoroethylene.

4. The molded article according to claim 3, wherein, as measured by X-ray photoelectron spectroscopy, the content ratio of element F to element C on the surface of the molded article is 1.3 or more.

5. When the surface of the molded body was measured by total internal reflection, the wavenumber was 1200 cm. －１ Wavenumber 1453 cm⁻¹ for absorption peak intensity －１ The molded article according to claim 4, wherein the ratio of absorption peak intensities is 0.7 or less.

6. A method for producing a molded article, comprising fluorinating an untreated molded article containing a fluorine-containing polymer that includes constituent units based on monomers having C-H bonds in a liquid, thereby converting the C-H bonds to C-F bonds in a region extending from the surface in the thickness direction to at least 1 μm.

7. The method for producing a molded article according to claim 6, wherein the monomer having a C-H bond is at least one selected from the group consisting of ethylene, vinyl fluoride, trifluoroethylene, 1,2-difluoroethylene, and vinylidene fluoride.

8. The method for producing a molded article according to claim 6 or 7, wherein the fluorine-containing polymer comprises a structural unit based on ethylene and a structural unit based on tetrafluoroethylene.

9. The method for producing a molded article according to claim 6 or 7, wherein the fluorination in the liquid is carried out by introducing fluorine gas in the presence of a fluorine-containing solvent and an aromatic hydrocarbon solvent.

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