Fluoropolymer film, rubber molded body, and manufacturing method of rubber molded body

Abstract

The fluoropolymer film provided by this invention comprises a fluoropolymer, and the average value of its elongation at break in a first in-plane direction and its elongation at break in a second in-plane direction orthogonal to the first in-plane direction at 180°C is 1200% or more. This fluoropolymer film can be used as a coating film for the surface of a rubber-containing substrate in a rubber molded body, and is suitable for manufacturing rubber molded bodies having a surface coated by this film.

Description

Technical Field

[0001] This invention relates to a fluoropolymer film, a rubber molded body, and a method for manufacturing the rubber molded body. Prior Technology

[0002] Fluoropolymer membranes are chemically stable and are therefore used as coatings for the surfaces of rubber-containing substrates. Rubber molded bodies comprising a rubber-containing substrate and a fluoropolymer membrane covering its surface are used as diaphragms, rollers, sealing materials, etc. Patent Document 1 discloses a diaphragm whose surface is coated with a fluoropolymer membrane. The diaphragm of Patent Document 1 exhibits high durability against atmospheric ozone or fuels. Previous technical documents Patent documents

[0003] Patent Document 1: Thin Film of Japanese Patent Application No. 53-182502 (Japanese Patent Application No. 55-98854) Summary of the Invention

[0004] [The problem the invention aims to solve]

[0005] If rubber is shaped while the fluoropolymer film is placed inside a mold, the formation of a rubber-containing substrate and the coating with the fluoropolymer film can be carried out simultaneously, allowing for the efficient manufacture of rubber molded articles. However, in the above-mentioned shaping process, cracks may occur in the fluoropolymer film coating the rubber-containing substrate. Furthermore, according to the present inventors' research, cracks are particularly prone to occur when coating the surface of a protrusion extending from the base of the rubber-containing substrate.

[0006] The object of the present invention is to provide a coating film that can be used as a coating film for the surface of a rubber-containing substrate in a coated rubber molded body, and is suitable for manufacturing a fluoropolymer film of a rubber molded body having a surface coated by the film. [Technical means to solve the problem]

[0007] This invention provides a fluoropolymer membrane comprising fluoropolymer. The average value of the tensile elongation at break in the first direction in the plane and the tensile elongation at break in the second direction in the plane orthogonal to the first direction is 1200% or more under an atmosphere of 180°C.

[0008] In another embodiment, the present invention provides a rubber molded body comprising: Contains a rubber-based substrate and a resin film. The aforementioned rubber-containing substrate has a surface coated with the aforementioned resin film. The resin film described above is the fluororesin film of the present invention.

[0009] In another embodiment, the present invention provides a method for manufacturing a rubber molded article. It is a method for manufacturing a rubber molded body comprising a resin film and a rubber-containing substrate, wherein the rubber-containing substrate has a surface covered by the resin film. This includes shaping the rubber by placing the aforementioned resin film within a mold to obtain the aforementioned rubber molded body. The resin film described above is the fluororesin film of the present invention.

[0010] In another embodiment, the present invention provides a method for manufacturing a rubber molded body. It is a method for manufacturing a rubber molded body comprising a resin film and a rubber-containing substrate, wherein the rubber-containing substrate has a surface covered by the resin film. In the above-mentioned rubber molded body, The aforementioned resin film is a fluoropolymer film and is free of cracks. The aforementioned surface includes the surface of the protrusion projecting from the base of the aforementioned rubber-containing substrate. The aforementioned protrusion has a height of 10 mm or more. The resin film covers the protrusion from its top and across its height. The above manufacturing method includes: The rubber molded body is obtained by shaping the rubber with the fluoropolymer film of the present invention disposed in the mold.

[0011] In another embodiment, the present invention provides a method for manufacturing a rubber molded body. It is a method for manufacturing a rubber molded body comprising a resin film and a rubber-containing substrate, wherein the rubber-containing substrate has a surface covered by the resin film. In the above-mentioned rubber molded body, The aforementioned resin film is a fluoropolymer film and is free of cracks. The aforementioned surface includes the surface of the protrusion projecting from the base of the aforementioned rubber-containing substrate. The aforementioned protrusion has a height of 10 mm or more. The resin film covers the protrusion from its top and across its height. The above manufacturing method includes: The rubber molded body described above is obtained by shaping the rubber with the resin film placed inside the mold; As the aforementioned resin film, a resin film having a tensile elongation at break that does not crack when the state of the film changes to the depth direction of the recess of the mold corresponding to the aforementioned protrusion along the shape of the recess. [Effects of the Invention]

[0012] The fluoropolymer film of the present invention having the above-mentioned elongation at break is suitable for manufacturing rubber molded bodies having a surface covered by the film. Simple Explanation of the Diagram

[0013] Figure 1 is a cross-sectional view illustrating one example of the fluoropolymer membrane of the present invention. Figure 2 is a schematic diagram of an example of an apparatus for manufacturing the fluoropolymer membrane of the present invention. Figure 3A is a top view illustrating an example of the rubber molded body of the present invention. Figure 3B is a cross-sectional view of the rubber molded body in Figure 3A, section IIIB-IIIB. Figure 4A is a top view illustrating an example of the rubber molded body of the present invention. Figure 4B is a cross-sectional view of the rubber molded body in Figure 4A, from section IVB to IVB. Figure 5A is a top view illustrating an example of the rubber molded body of the present invention. Figure 5B is a cross-sectional view of the rubber molded body in Figure 5A, VB-VB. Figure 6 shows an observation image of the state of the fluoropolymer membrane of Example 1 after a shaping test. Figure 7 shows an observation image of the state of the fluoropolymer membrane of Comparative Example 1 after a shaping test. Implementation

[0014] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The present invention is not limited to the following embodiments.

[0015] [Fluoropolymer membrane] The fluoropolymer film of this embodiment is shown in FIG1. ​​The fluoropolymer film 1 in FIG1 contains fluoropolymer. Regarding the fluoropolymer film 1, the average value (hereinafter referred to as average elongation) of the tensile elongation at break in a first in-plane direction and the tensile elongation at break in a second in-plane direction orthogonal to the first direction under an atmosphere of 180°C is 1200% or more. According to the fluoropolymer film 1, cracking of the film 1 can be suppressed during the above-mentioned rubber shaping process. Furthermore, 180°C corresponds to a typical processing temperature in the rubber shaping process.

[0016] The average elongation can be above 1250%, 1300%, 1350%, 1400%, 1450%, 1500%, 1550%, 1600%, 1650%, and even above 1700%. The upper limit of the average elongation is, for example, below 1800%.

[0017] The first direction is, for example, the MD direction. The second direction is, for example, the TD direction. Typically, the MD direction is the winding direction during the film-making process of the fluoropolymer film 1. Typically, the TD direction is the direction perpendicular to the winding direction within the surface of the fluoropolymer film 1. Regarding the strip-shaped fluoropolymer film 1, the first direction and the second direction can be the length direction and the width direction, respectively.

[0018] Regarding the fluoropolymer film 1, the tensile strength in the first and / or second directions at 180°C can be 7.0 MPa or more, or 7.5 MPa or more, 8.0 MPa or more, 8.5 MPa or more, 9.0 MPa or more, and further 9.5 MPa or more. Appropriate control of the tensile strength can help to more effectively suppress the formation of the aforementioned cracks. However, in most cases, it is difficult to simultaneously achieve both high tensile strength and high elongation at break. The upper limit of the tensile strength is, for example, 20.0 MPa or less, and can be 17.0 MPa or less, 16.0 MPa or less, 15.0 MPa or less, 14.0 MPa or less, 13.0 MPa or less, and further 12.0 MPa or less.

[0019] The elongation at break and tensile strength can be evaluated by tensile testing of the fluoropolymer film 1.

[0020] The fluoropolymer membrane 1 in Figure 1 has a modified surface (hereinafter referred to as the modified surface) 11. By using the fluoropolymer membrane 1 in a manner that the modified surface 11 is bonded to a rubber-containing substrate, the adhesion of the fluoropolymer membrane 1 to the rubber-containing substrate can be improved.

[0021] The adhesion of the modified surface 11 is expressed by the peel adhesion, which can be 4.0 N / 19 mm or more, or 4.5 N / 19 mm or more, 5.0 N / 19 mm or more, 5.5 N / 19 mm or more, 6.0 N / 19 mm or more, 6.5 N / 19 mm or more, 7.0 N / 19 mm or more, and further 7.5 N / 19 mm or more. The peel adhesion is evaluated by applying the fluoropolymer film 1 to an adhesive tape (No. 31B manufactured by Nitto Denko, 80 μm thick) with the adhesive side of the tape facing the modified surface 11, followed by a 180° peel test where the adhesive tape is removed from the fluoropolymer film 1. The upper limit of the adhesion of the modified surface 11 is expressed by the peel adhesion, for example, 15.0 N / 19 mm or less. Furthermore, No. 31B has sufficient adhesion for evaluating the peel adhesion.

[0022] The fluoropolymer membrane 1 in Figure 1 has a modified surface 11 on one main surface. The fluoropolymer membrane 1 may have modified surfaces 11 on two main surfaces. When the fluoropolymer membrane 1 has two or more modified surfaces 11, the adhesion of the modified surfaces 11 may be the same or different among the modified surfaces 11.

[0023] The fluoropolymer membrane 1 in Figure 1 has a modified surface 11 on the entire surface of one main surface. The fluoropolymer membrane 1 may have a modified surface 11 on only a portion of the main surface. Alternatively, the fluoropolymer membrane 1 may have two or more modified surfaces 11 on one main surface.

[0024] The thickness of the fluoropolymer membrane 1 is, for example, 10~300 μm, 30~250 μm, or even 50~200 μm.

[0025] The fluoropolymer membrane 1 in Figure 1 is a single layer. As long as the fluoropolymer membrane 1 has the above-mentioned elongation at break, it can also be a laminate of two or more layers.

[0026] Examples of fluoropolymers include at least one selected from ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA), polyvinyl chloride trifluoroethylene (PCTFE), and polytetrafluoroethylene (PTFE). The fluoropolymer may be at least one selected from ETFE, FEP, and PFA, and may be ETFE.

[0027] The melt flow rate (MFR) of fluoropolymers (excluding PTFE, whose melt flow rate is difficult to evaluate due to its very high melt viscosity) is, for example, 30 g / 10 min or less, and may be 28 g / 10 min or less, 25 g / 10 min or less, or even 22 g / 10 min or less. The lower limit of MFR is, for example, 0.5 g / 10 min or more, and may be 1 g / 10 min or more, 1.5 g / 10 min or more, 2 g / 10 min or more, 2.5 g / 10 min or more, 3 g / 10 min or more, 3.5 g / 10 min or more, 4 g / 10 min or more, 4.5 g / 10 min or more, 5 g / 10 min or more, or even 7 g / 10 min or more. Proper control of MFR can help to more effectively suppress the formation of the aforementioned cracks. The melting temperature and loading for evaluating MFR can be specified according to the type of fluoropolymer, as shown in Table 1 below. Furthermore, the melting temperatures correspond to the typical temperatures (thermoforming temperatures) at which each resin is thermoformed.

[0028] [Table 1] Melting temperature (°C) Load (kg) ETFE 297 5 FEP 372 5 PFA 372 2 PCTFE 265 31.6

[0029] The melting point of fluoropolymers evaluated by differential scanning calorimetry (DSC) is, for example, below 250°C, but may be below 245°C, 240°C, 235°C, or even below 230°C. The lower limit of the melting point is, for example, above 200°C, but may be above 205°C. Proper control of the melting point can help to more effectively suppress the formation of the aforementioned cracks. In this specification, the melting point of the fluoropolymer is defined as the temperature of the maximum endothermic peak caused by the melting of the fluoropolymer (melting peak temperature), measured when the fluoropolymer is heated using DSC at a certain heating rate (10°C / min). However, in order to eliminate the thermal process during film formation and clarify the inherent characteristics of the resin, the melting point is evaluated by a second run of DSC. The melting point of fluoropolymers varies, for example, depending on molecular weight, molecular weight distribution, polymerization method, polymerization process, etc.

[0030] The fluoropolymer membrane 1 may contain fluoropolymer as a main component. In this specification, "main component" refers to the component with the highest content. The content of fluoropolymer in the fluoropolymer membrane 1 may be, for example, 50% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more, 90% by weight or more, 95% by weight or more, and further 99% by weight or more. The fluoropolymer membrane 1 may be composed of fluoropolymer. The fluoropolymer membrane 1 may contain two or more types of fluoropolymer.

[0031] The fluoropolymer membrane 1 may contain materials other than fluoropolymers. Examples of other materials in the fluoropolymer membrane 1 are resins other than fluoropolymers. Examples of such resins are polyolefins such as polyethylene and polypropylene, and polyvinylidene chloride. The content of other materials in the fluoropolymer membrane 1 may be, for example, 20% by weight or less, 10% by weight or less, 5% by weight or less, 3% by weight or less, and further 1% by weight or less.

[0032] The shape of the fluoropolymer film 1 can be, for example, a polygon including squares and rectangles, a circle, an ellipse, or a strip. Polygons may have rounded corners. However, the shape of the fluoropolymer film 1 is not limited to the examples described above. Polygonal, circular, and elliptical fluoropolymer films 1 can be circulated as single sheets, or strip-shaped fluoropolymer films 1 can be circulated as a winding body (roller) wound around a core. The width of the strip-shaped fluoropolymer film 1 and the width of the winding body formed by winding the strip-shaped fluoropolymer film 1 can be freely set.

[0033] Fluoropolymer membrane 1 is typically non-porous. Fluoropolymer membrane 1 may be a non-porous membrane that does not have pores connecting the two main surfaces, at least in the area of ​​use.

[0034] Fluororubber membrane 1, based on the high liquid-repellent (water-repellent and oil-repellent) properties of fluoropolymer, can be an impermeable membrane that prevents fluids such as water, aqueous solutions, oil, and organic liquids from passing through in the thickness direction. Furthermore, based on the high insulating properties of fluoropolymer, fluoropolymer membrane 1 can be an insulating membrane (non-conductive membrane). Insulation properties are, for example, expressed as a surface resistivity of 1 × 10¹⁴ Ω / □ or higher.

[0035] The method for manufacturing the fluoropolymer membrane 1 is not limited. The fluoropolymer membrane 1 can be manufactured using various film forming methods such as melt extrusion, cutting, and casting. Mechanical properties such as tensile elongation at break can be adjusted according to the composition of the fluoropolymer membrane 1 or by mechanical treatments such as stretching and calendering of the membrane. Furthermore, the fluoropolymer membrane 1 having the modified treatment surface 11 can be manufactured by modifying a base membrane containing fluoropolymer. One example of the above method is shown below. However, the method for manufacturing the fluoropolymer membrane 1 having the modified treatment surface 11 is not limited to the following example.

[0036] Typically, the original membrane is a membrane with the same structure as the fluoropolymer membrane 1, except that it has the modified treatment surface 11.

[0037] Examples of modification treatments for the original film include sputtering etching, ion beam treatment, laser etching, sandblasting, and treatment using sandpaper. However, the modification treatment is not limited to the above examples as long as it forms the modified surface 11. In terms of efficiently forming the modified surface 11, the modification treatment can be sputtering etching or ion beam treatment, and it can be sputtering etching.

[0038] Typically, sputtering etching can be performed by applying a high-frequency voltage to the original film while the chamber containing the original film is depressurized and an atmospheric gas is introduced into the chamber. The high-frequency voltage can be applied, for example, using a cathode in contact with the original film and an anode separated from the original film. In this case, a modified treatment surface 11 is formed on the main surface of the anode side, which is the exposed surface of the original film. Known apparatus can be used in sputtering etching.

[0039] Examples of ambient gases include rare gases such as helium, neon, and argon; inert gases such as nitrogen; and reactive gases such as oxygen and hydrogen. In terms of efficiently forming the modified treatment surface 11, the ambient gas can be at least one selected from argon and oxygen, and can be oxygen. Only one ambient gas may be used.

[0040] The frequency of the high-frequency voltage is, for example, 1~100 MHz, or 5~50 MHz. The pressure in the chamber during processing is, for example, 0.05~200 Pa, or 0.5~100 Pa.

[0041] The energy of the sputtering etching process (the product of the power applied to each unit area of ​​the original film and the processing time) is, for example, 0.1~100 J / cm 2, or 0.1~50 J / cm 2, 0.1~40 J / cm 2, and further 0.1~30 J / cm 2.

[0042] The sputtering and etching process can be set as a batch process or a continuous process. An example of a continuous process is illustrated in Figure 2.

[0043] One example of a continuous processing apparatus is shown in Figure 2. The processing apparatus 100 of Figure 2 includes a chamber 101, a roller electrode 102 disposed within the chamber 101, and a curved plate electrode 103. A pressure reducing device 104 for reducing pressure in the chamber 101 and a gas supply device 105 for supplying atmospheric gas to the chamber 101 are connected to the chamber 101. The roller electrode 102 is connected to a high-frequency power supply 106, and the curved plate electrode 103 is grounded. The original film 107 is in the form of a strip and is wound around a feed roller 108. The original film 107 can be continuously fed from the feed roller 108, so that it passes along the roller electrode 102 and between the roller electrode 102 and the curved plate electrode 103, while a high-frequency voltage is applied to perform continuous processing. In the example of Figure 2, a modified processing surface 11 is formed on the main surface of the original film 107 on the side of the curved plate electrode 103. The processed original film 107 is wound onto a take-up roller 109.

[0044] The fluoropolymer film 1 can be used, for example, as a coating film for the surface of a rubber-containing substrate in a rubber-coated molded body. The coating film is typically used in a manner that follows the shape of the surface of the rubber-containing substrate. In this case, the coating film inevitably undergoes significant stretching according to the aforementioned shape. Furthermore, in shaping processes performed with the fluoropolymer film 1 placed within a mold, the fluoropolymer film 1 exhibits a high degree of stretching during the shaping of the rubber.

[0045] Examples of rubber molded bodies include diaphragms, rollers, sealing materials (gaskets, O-rings, valve components, etc.) and tubular bodies (tubes, hoses, etc.). Specific examples of rubber molded bodies are shown below. However, rubber molded bodies are not limited to the specific examples mentioned above and below.

[0046] The applications of fluoropolymer membrane 1 are not limited to the examples mentioned above.

[0047] [Rubber Molded Body] An example of a rubber molded body according to this embodiment is illustrated in Figures 3A and 3B. In Figure 3B, a cross-section IIIB-IIIB of the rubber molded body 21 of Figure 3A is shown. The rubber molded body 21 of Figures 3A and 3B is a corrugated diaphragm. The rubber molded body 21 includes a rubber-containing substrate 22 and a fluoropolymer film 1. The rubber-containing substrate 22 has a surface 23 covered by the fluoropolymer film 1. Furthermore, since the surface 23 is corrugated, the fluoropolymer film 1 is locally (e.g., at the top 24 of the corrugation) more strongly during the manufacture of the rubber molded body 21.

[0048] The entire surface of the rubber molded body 21 may be surface 23, or only a portion of its surface may be surface 23.

[0049] The rubber-containing substrate 22 typically contains rubber as a main component. Examples of rubber include butyl rubber, natural rubber, ethylene propylene rubber (EPDM), silicone rubber, and fluororubber. The rubber-containing substrate 22 may also contain materials other than rubber, such as inorganic fillers, organic fillers, reinforcing fibers, antioxidants, and plasticizers.

[0050] The rubber molded body of the present invention is not limited to the above examples as long as it has surface 23. Examples of rubber molded bodies other than diaphragms include rollers, sealing materials (gaskets, O-rings, valve components, etc.) and tubular bodies (tubes, hoses, etc.).

[0051] Another example of the rubber molded body of this embodiment is shown in Figures 4A and 4B. In Figure 4B, a partial enlarged view of the cross section IVB-IVB and the vicinity of the protrusion 34 in the rubber molded body 31 of Figure 4A is shown. The rubber molded body 31 in Figures 4A and 4B is a gasket. The rubber molded body 31 has a surface 23 covered by a fluoropolymer film 1. The rubber-containing substrate 32 of the rubber molded body 31 has a base 33 and a protrusion 34 protruding from the base 33. The surface 23 includes the surface of the protrusion 34. During the manufacture of the rubber molded body 31, the fluoropolymer film 1 is locally and strongly extended, for example, on the surface of the protrusion 34 (especially the top 35 of the protrusion 34 or the connection 40 between the top 35 and the sidewall portion 37), or at the surface 38 protruding from the protrusion 34 in the base 33 and the connection 36 between the sidewall portion 37 of the protrusion 34. However, in the rubber molded body 31 with fluoropolymer film 1, even in the part that is stretched more strongly during manufacturing, it is not easy for fluoropolymer film 1 to crack.

[0052] The protrusion 34 may have a height H of 8 mm or more, 10 mm or more, 12 mm or more, 13 mm or more, and even 14 mm or more. In these configurations, especially in the configuration where the protrusion 34 has a height H of 10 mm or more, the degree of local extension of the fluoropolymer film 1 is further increased during the manufacture of the rubber molded body 31.

[0053] The fluoropolymer film 1 can cover the protrusion 34 from the top 35 of the protrusion 34 across the height H of the protrusion 34. The covering can reach the connecting portion 36, or it can extend beyond the connecting portion 36 to the surface 38 of the base 33. The fluoropolymer film 1 can cover the entire surface of the protrusion 34, or it can cover a portion of it. In other words, the surface 23 can include the entire surface of the protrusion 34, or it can include a portion of the surface.

[0054] The width W1 of the protrusion 34 can be less than 50 mm, less than 20 mm, or even less than 10 mm. The lower limit of the width W1 is, for example, more than 3 mm. The smaller the width W1, the greater the degree of local extension of the fluoropolymer film 1 during the manufacture of the rubber molded body 31. The width W1 is the minimum width of the cross section 30 of the protrusion 34 cut parallel to the surface 38 of the base 33 and at a distance of 0.1 times (0.1H) of the height H of the protrusion 34 from the front end 39 of the protrusion 34.

[0055] The width W2 of the protrusion 34 can be less than 50 mm, less than 20 mm, or even less than 10 mm. The lower limit of the width W2 is, for example, more than 4 mm. The smaller the width W2, the greater the degree of local extension of the fluoropolymer film 1 during the manufacture of the rubber molded body 31. The width W2 is defined as the minimum distance between two parallel tangents of the cross-section 29 of the protrusion 34 cut parallel to the surface 38 of the base 33 and at a distance of 0.8 times (0.8H) of the height H of the protrusion 34 from the front end 39 of the protrusion 34.

[0056] The ratio of width W1 to width W2, W1 / W2, can be 0.5~2.0, 0.75~1.33, or even 0.85~1.18.

[0057] The maximum value of the inclination angle θ formed by the sidewall portion 37 of the protrusion 34 relative to the surface 38 of the base 33 can be 60 degrees or more, 70 degrees or more, 80 degrees or more, and further 90 degrees or more. The upper limit of the above maximum value is, for example, 110 degrees or less. The larger the above maximum value, the greater the degree of local extension of the fluoropolymer film 1 during the manufacture of the rubber molded body 31.

[0058] The rubber molded body 31 may have two or more protrusions 34. The surface 23 may include the surface of two or more protrusions 34. The fluoropolymer film 1 may be continuously coated with two or more protrusions 34, or it may be coated individually. The interval between two or more protrusions 34 (the distance between the front ends 39) may be 50 mm or less, 20 mm or less, or even 15 mm or less.

[0059] Another example of the rubber molded body according to this embodiment is shown in Figures 5A and 5B. In Figure 5B, a cross section VB-VB of the rubber molded body 41 of Figure 5A is shown. The rubber molded body 41 of Figures 5A and 5B is a gasket. Except for the shape of the protrusion 34, the rubber molded body 41 has the same structure as the rubber molded body 31. The protrusion 34 of the rubber molded body 41 has a recess 42 at its top 35. The fluoropolymer film 1 covers the protrusion 34 from the top 35 of the protrusion 34 across the height H of the protrusion 34 in a manner that includes the recess 42. In this configuration, the extent to which the fluoropolymer film 1 extends locally is further increased during the manufacture of the rubber molded body 31. The fluoropolymer film 1 may cover the entire surface of the recess 42 or only a portion thereof.

[0060] In the rubber molded bodies 21, 31, and 41, the fluoropolymer film 1 can be in a state without cracks.

[0061] Rubber molded bodies 21, 31, and 41 can be manufactured by shaping rubber, for example, with a fluoropolymer film 1 disposed within a mold. Based on this, the present invention provides a method for manufacturing a rubber molded body. It is a method for manufacturing a rubber molded body comprising a resin film and a rubber-containing substrate, wherein the rubber-containing substrate has a surface covered by the resin film. This includes shaping the rubber by placing the aforementioned resin film within a mold to obtain the aforementioned rubber molded body. The above-mentioned resin film is a fluoropolymer film 1.

[0062] Examples of shaping processes include in-mold forming and film embedding. However, shaping processes are not limited to the above examples.

[0063] By using a fluoropolymer film 1 in the manufacture of rubber molded articles 21, 31, and 41, a rubber molded article can be obtained without cracks in the fluoropolymer film 1. The surface 23 of the rubber molded article includes a surface of a protrusion 34 protruding from the base 33 of the rubber-containing substrate 32. The protrusion 34 has a height of 10 mm or more, and the fluoropolymer film 1 covers the protrusion 34 from its top 35 across the height H of the protrusion 34. Based on this configuration, the present invention provides a method for manufacturing a rubber molded article. It is a method for manufacturing a rubber molded body comprising a resin film and a rubber-containing substrate, wherein the rubber-containing substrate has a surface covered by the resin film. In the above-mentioned rubber molded body, The aforementioned resin film is a fluoropolymer film and is free of cracks. The aforementioned surface includes the surface of the protrusion projecting from the base of the aforementioned rubber-containing substrate. The aforementioned protrusion has a height of 10 mm or more. The resin film covers the protrusion from its top and across its height. The above manufacturing method includes: The rubber molded body is obtained by shaping the rubber with the fluoropolymer film 1 placed in the mold.

[0064] The rubber molded body of this embodiment includes a fluoropolymer film 1 and a rubber-containing substrate 32. The rubber-containing substrate 32 has a surface 23 covered by the fluoropolymer film 1. The surface 23 includes the surface of a protrusion 34 protruding from the base 33 of the rubber-containing substrate 32. The protrusion 34 has a height of 10 mm or more. The fluoropolymer film 1 covers the surface of the protrusion 34 from the top 35 of the protrusion 34 across the height H of the protrusion 34 without cracking. According to this embodiment, a rubber molded body can be provided in which the surface of a protrusion of this height is covered without cracking by a molding method using a mold. According to this embodiment, the present invention provides a method for manufacturing a rubber molded body. It is a method for manufacturing a rubber molded body comprising a resin film and a rubber-containing substrate, wherein the rubber-containing substrate has a surface covered by the resin film. In the above-mentioned rubber molded body, The aforementioned resin film is a fluoropolymer film and is free of cracks. The aforementioned surface includes the surface of the protrusion projecting from the base of the aforementioned rubber-containing substrate. The aforementioned protrusion has a height of 10 mm or more. The resin film covers the protrusion from its top and across its height. The above manufacturing method includes: The rubber molded body described above is obtained by shaping the rubber with the resin film placed inside the mold; As the aforementioned resin film, a resin film having a tensile elongation at break that does not crack when the state of the film changes to the depth direction of the recess of the mold corresponding to the aforementioned protrusion along the shape of the recess.

[0065] The elongation at break without cracking can be determined based on the shape of the recess in the mold (e.g., the depth D of the recess, the opening size, the ratio of depth D to opening size, etc.), the temperature or pressure applied during the shaping process, etc. As shown in the following examples, for fluoropolymer films, it is important to prioritize ensuring sufficient elongation at break rather than balancing tensile strength and elongation at break. Example

[0066] The present invention will be further described in detail below with reference to embodiments. The present invention is not limited to the following embodiments.

[0067] First, the evaluation method for fluoropolymer membranes is shown.

[0068] [thickness] The thickness was determined using a micrometer (manufactured by Mitutoyo) as the average of the values ​​from at least four measurement points.

[0069] [Tensive elongation at break, tensile strength] The mechanical properties (elongation at break and tensile strength) based on tensile testing are evaluated as follows: Fluoropolymer film is punched into a dumbbell shape (No. 3) as specified in JIS K6251:2017 to form a test piece. Next, to suppress elongation during testing of the portion of the test piece other than the parallel portion (between the markings), a 35 mm section is reinforced at each end along the length direction using reinforcing tape (No. 360UL, manufactured by Nitto Denko). Reinforcement is performed by attaching the reinforcing tape to one side of the test piece. Then, a tensile test is conducted on the test piece using a tensile testing machine (Tensilon universal testing machine manufactured by Orientec). The test temperature is set to 180°C (starting after a 5-minute preheating period for the test piece), and the tensile speed is set to 200 mm / min. The tensile test is performed in both the MD direction (winding direction during film formation; length direction) and the TD direction (width direction) of the fluoropolymer film. Let the length of the specimen at the fracture point be L1, and calculate the ratio L1 / L0 relative to the length L0 of the specimen before the test. Let this ratio be the tensile elongation at break (unit: %). Furthermore, for the tensile test in the MD direction, divide the maximum stress (tensile force) recorded before the specimen fractures by the cross-sectional area of ​​the parallel portion of the specimen before the test to calculate the tensile strength (unit: MPa).

[0070] [Peel adhesion] Peel adhesion was evaluated as follows. First, the fluoropolymer film was cut into short strips 19 mm wide and 150 mm long to form test pieces. Second, using double-sided adhesive tape (Nitto Denko No. 500), the test pieces were adhered to the surface of a stainless steel plate. The adhesion was performed with the entire test piece in contact with the stainless steel plate, exposing the modified surface of the fluoropolymer film. The double-sided adhesive tape was selected to have sufficient adhesion to prevent the test piece from peeling off the stainless steel plate during the evaluation. Next, a single-sided adhesive tape (Nitto Denko No. 31B, 80 μm thick, acrylic adhesive) with a width of 19 mm and a length of 200 mm was adhered to the exposed surface of the test piece. The bonding process is performed with the long sides of the test piece and the single-sided adhesive tape aligned, and one end of the single-sided adhesive tape extending 120 mm across the test piece without contacting the test piece, thus becoming a free end. The adhesive layer of the single-sided adhesive tape, except for the free end, is entirely in contact with the test piece. Furthermore, during bonding, to ensure a more secure bond between the single-sided adhesive tape and the test piece, a 2 kg pressing roller, as specified in JIS Z0237:2009, is cyclically rotated once at 25°C. Next, the test sample, after being allowed to stand for 30 minutes following the cyclic rotation of the pressing roller to stabilize the bond between the single-sided adhesive tape and the test piece, is placed in a tensile testing machine. The long side of the test piece is aligned with the direction of the machine's clamps, and one clamp holds the free end of the single-sided adhesive tape while the other clamp holds the test piece and the stainless steel plate. Next, a 180° peel test was conducted, in which the single-sided adhesive tape was peeled off from the test piece at a peel angle of 180° and a test speed of 300 mm / min. After the test began, the measured value of the first 20 mm peeled length was ignored, and the average value of the measured values ​​of the subsequent 60 mm peeled lengths was taken as the peel adhesion of the test piece. The test was conducted in an environment with a temperature of 25±1℃ and a relative humidity of 50±5%.

[0071] [MFR] The MFR of ETFE contained in the fluoropolymer membranes of Examples 1 and 2 was determined according to the industry standard ASTM D3159-20 for ETFE (melting temperature 297°C, load 5 kg). The MFR of PFA contained in the fluoropolymer membrane of Comparative Example 3 was calculated by measuring the weight (g) of PFA flowing out per unit time (10 minutes) from a nozzle with a diameter of 2 mm and a length of 8 mm under the test conditions of a melting temperature of 372°C and a load of 2 kg. The MFR of FEP contained in the fluoropolymer membrane of Comparative Example 4 was determined according to the industry standard ASTM D2216 for FEP (melting temperature 372°C, load 5 kg).

[0072] [Melting Point] The melting point of the fluoropolymer membrane was evaluated by DSC as follows: 10 ± 5 mg of the fluoropolymer membrane was added to the lower plate of an aluminum pot, and the upper plate was used as a lid. The pot was then sealed under vertical pressure. Next, the temperature was maintained at 0°C for 1 minute, then increased to 260°C at a rate of 10°C / min. After maintaining this temperature at 260°C for 1 minute, the temperature was decreased to 0°C at a rate of 10°C / min (first run). Next, the temperature was maintained at 0°C for 1 minute, then increased again to 260°C at a rate of 10°C / min (second run). The melting peak temperature at this point was taken as the melting point of the fluoropolymer. The DSC apparatus and analysis software used were the DSC200F3 and Proteus software manufactured by NETZCH Japan.

[0073] [Shaping Experiment] A shaping process using a fluoropolymer film to simulate in-mold molding of rubber was performed. Visual inspection was conducted to confirm whether any cracks were observed in the fluoropolymer film on the surface of the resulting rubber molded body. The shaping process was carried out according to the following procedure.

[0074] A fluoropolymer film is overlapped with an uncured butyl rubber sheet (hardness 28 as evaluated by a Type A hardness tester). The protrusion 34 of the gasket is placed on the forming surface of a mold having two or more hypothetical recesses. Each recess has the same shape and has a rectangular opening, a cross-sectional shape (cross-sectional area 10 mm²), and a depth of 15 mm. The placement is carried out by contacting the modified surface of the fluoropolymer film with the butyl rubber sheet, with the fluoropolymer film forming the mold side. Next, using a high-temperature, high-pressure press (manufactured by MIKADO TECHNOS, high-temperature heating and pressurizing device MKP-1500D-WH-ST), a shaping process is performed at a temperature of 170°C and a pressure of 20 kN for 5 seconds (pressure molding) followed by 4.5 kN for 10 minutes (vulcanization) to obtain a rubber molded body with two or more protrusions (height H=15 mm) that protrude from the base and correspond to the concave parts of the mold, and the entire surface of the protrusions is covered with a fluoropolymer film. The protrusions of the obtained rubber molded body are visually inspected, and the condition where no cracks are observed in the fluoropolymer film is considered good, while the condition where cracks are observed is considered unacceptable.

[0075] (Example 1) ETFE resin (LM-720AP manufactured by AGC) was melt-extruded to form an ETFE film with a thickness of 50 μm. Next, a surface modification treatment using sputtering etching was performed on one side of the ETFE film to obtain the fluoropolymer film of Example 1. The sputtering etching conditions were the same for all fluoropolymer films of the examples and comparative examples.

[0076] (Example 2) An ETFE membrane with a thickness of 100 μm was prepared. Otherwise, the fluoropolymer membrane of Example 2 was obtained in the same manner as in Example 1.

[0077] (Example 3) The batch of ETFE resin (LM-720AP manufactured by AGC) was changed, and the fluoropolymer film of Example 3 was obtained in the same manner as in Example 2.

[0078] (Example 4) An ETFE membrane with a thickness of 200 μm was prepared. Otherwise, the fluoropolymer membrane of Example 4 was obtained in the same manner as in Example 1.

[0079] (Example 5) Using LM-730AP manufactured by AGC as the ETFE resin, the fluoropolymer film of Example 5 was obtained in the same manner as in Example 1.

[0080] (Example 6) The batch of ETFE resin (LM-730AP manufactured by AGC) was changed, and an ETFE membrane with a thickness of 100 μm was made. Otherwise, the fluoropolymer membrane of Example 6 was obtained in the same manner as in Example 5.

[0081] (Comparative Example 1) Using EP-546 manufactured by Daikin Industries as the ETFE resin, the fluoropolymer film of Comparative Example 1 was obtained in the same manner as in Example 1.

[0082] (Comparative Example 2) An ETFE membrane with a thickness of 100 μm was prepared. Otherwise, the fluoropolymer membrane of Comparative Example 2 was obtained in the same manner as Comparative Example 1.

[0083] (Comparative Example 3) PFA resin (DuPont 920HP Plus) was melt-extruded to form a PFA film with a thickness of 45 μm. Next, a surface modification treatment using sputtering etching was performed on one side of the PFA film to obtain the fluoropolymer film of Comparative Example 3.

[0084] (Comparative Example 4) A surface modification treatment using sputtering etching was performed on one side of a 50 μm thick FEP film (NF-0050 manufactured by Daikin Industries) to obtain the fluoropolymer film of Comparative Example 4.

[0085] The evaluation results of each fluororesin and fluororesin film are shown in Tables 2 and 3 below. Furthermore, regarding Example 1 and Comparative Example 1, magnified images of the protrusions in the rubber molded bodies obtained in the shaping test are shown in Figures 6 and 7, respectively.

[0086] [Table 2] Fluororubber type MFR (g / 10 minutes) Melting point (°C) Example 1 ETFE 15.1 225.2 2 ETFE 15.1 225.2 3 ETFE 20.0 225.8 4 ETFE 15.1 225.2 5 ETFE 26.0 225.2 6 ETFE 23.0 225.2 Comparative example 1 ETFE 6.0 252.9 2 ETFE 6.0 252.9 3 PFA 2.0 310 4 FEP 3.0 270

[0087] [Table 3] Fluoropolymer membrane Thickness (μm) Tensile test (at 180℃) Following force (N / 19 mm) shaping test Elongation at break MD(%) Elongation at break TD(%) Elongation at break average(%) Tensile strength MD(MPa) Example 1 50 1650 1620 1635 10.0 7.81 good 2 100 1658 1627 1643 9.6 7.98 good 3 100 1698 1720 1709 8.5 7.84 good 4 200 1672 1640 1656 8.7 7.76 good 5 50 1428 1350 1389 7.8 7.18 good 6 100 1611 1594 1602 7.7 6.92 good Comparative example 1 50 880 891 885 14.2 7.00 No 2 100 1080 1093 1086 12.3 7.00 No 3 45 711 782 746 27.9 - No 4 50 576 590 583 7.5 - No ※ "-" in the table indicates that it was not measured.

[0088] As shown in Table 3, no cracks were generated in the fluoropolymer film of the Examples during the shaping test (refer to Figure 6 for Example 1). On the other hand, cracks were generated in the fluoropolymer film of the Comparative Examples during the shaping test (refer to Figure 7 for Comparative Example 1). As shown in Figure 7, a plurality of cracks 71 were generated in the protrusions. [Industrial Applicability]

[0089] The fluoropolymer film of the present invention can be used, for example, as a coating film for the surface of a rubber-containing substrate of a coated rubber molded body.

[0090] 1: Fluoropolymer membrane 11: Modified surface 21, 31, 41: Rubber molded body 22, 32: Substrate containing rubber 23: Surface 24: Top 29: Section 30: Section 33: Base 34:convex part 35: Top 36: Connecting part 37: Side wall portion 38: noodles 39: Front-end 40: Connecting part 42: concave part 71: Crack 100: Processing device 101: Chamber 102: Roller Electrode 103: Curved plate electrode 104: Pressure reducing device 105: Gas supply device 106: High-frequency power supply 107: Original membrane 108: Feed Roller 109: Take-up roller H: Height W1, W2: Width θ: Inclination angle

Claims

1. A fluoropolymer membrane comprising a fluoropolymer, wherein the average value of the elongation at break in a first in-plane direction and the elongation at break in a second in-plane direction orthogonal to the first in-plane direction at 180°C is 1350% or more, the tensile strength in the first and / or second directions at 180°C is 7.7 MPa or more, the melting point of the fluoropolymer as evaluated by differential scanning calorimetry (DSC) is 250°C or less, and the fluoropolymer membrane has a modified surface.

2. The fluoropolymer film of claim 1 has a tensile strength of 20.0 MPa or less in the first direction and / or the second direction in an atmosphere at 180°C.

3. The fluoropolymer film of claim 1 or 2, wherein the adhesion of the aforementioned surface is expressed by peel adhesion and is 4.0 N / 19 mm or more. The peel adhesion is evaluated by a 180° peel test in which the adhesive tape (No. 31B manufactured by Nitto Denko, 80 μm thick) is peeled off from the fluoropolymer film after the adhesive surface of the adhesive tape is attached to the aforementioned surface.

4. The fluoropolymer film of claim 1 or 2, wherein the fluoropolymer is an ethylene-tetrafluoroethylene copolymer.

5. The fluoropolymer film, as requested in item 1 or 2, has a thickness of 10 to 300 μm.

6. The fluoropolymer film of claim 1 or 2 is a coating film for the surface of a rubber-containing substrate of a coated rubber molded body.

7. A rubber molded body comprising a rubber-containing substrate and a resin film, wherein the rubber-containing substrate has a surface covered by the resin film, and the resin film is a fluoropolymer film as claimed in any one of claims 1 to 6.

8. The rubber molded article of claim 7, wherein the surface includes a surface of a protrusion protruding from the base of the rubber-containing substrate, the protrusion having a height of 10 mm or more.

9. The rubber molded body of claim 8, wherein the resin film covers the protrusion from the top of the protrusion across the height of the protrusion.

10. A method for manufacturing a rubber molded body, comprising a resin film and a rubber-containing substrate, wherein the rubber-containing substrate has a surface covered by the resin film, and the method includes shaping the rubber in a state in which the resin film is disposed in a mold to obtain the rubber molded body, wherein the resin film is a fluoropolymer film as claimed in any one of claims 1 to 6.

11. A method for manufacturing a rubber molded body, comprising a resin film and a rubber-containing substrate, wherein the rubber-containing substrate has a surface covered by the resin film, and wherein in the rubber molded body, the resin film is a fluoropolymer film and is free of cracks, the surface includes a surface of a protrusion protruding from the base of the rubber-containing substrate, the protrusion having a height of 10 mm or more, and the resin film covering the protrusion from the top of the protrusion across the height of the protrusion, the manufacturing method comprising: The rubber molded body described above is obtained by shaping the rubber with any of the fluoropolymer films as claimed in items 1 to 6 placed in a mold.

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