Biaxially oriented polyarylene sulfide film, biaxially oriented polyarylene sulfide film roll, electrolyte membrane reinforcing member, fuel cell, water electrolysis device, metallized film, current collector foil, secondary battery, film capacitor, electrically insulating paper for motor, and motor

Abstract

This biaxially oriented polyarylene sulfide film contains a polyarylene sulfide resin as a main constituent component. The biaxially oriented polyarylene sulfide film has a thickness variation in the film width direction of 0.5% to 10.0% inclusive in a width of 300 mm around the central part in the width direction of the film, an orientation angle from the film longitudinal direction of more than -35° but less than 35°, not less than -90° but less than -55°, or more than 55° but not more than 90°, and a difference between the maximum value and the minimum value of the orientation angle of 0.5° to 20.0° inclusive. The present invention provides a biaxially oriented polyarylene sulfide film which is capable of suppressing warpage at the time of processing, and is excellent in terms of pressure uniformity when a large number of the biaxially oriented polyarylene sulfide films are stacked and pressurized.

Description

Biaxially oriented polyarylene sulfide film, biaxially oriented polyarylene sulfide film roll, electrolyte membrane reinforcing member, fuel cell, water electrolysis device, metallized film, current collecting foil, secondary battery, film capacitor, electrical insulating paper for motor, and motor

[0001] The present invention relates to a biaxially oriented polyarylene sulfide film, a biaxially oriented polyarylene sulfide film roll, an electrolyte membrane reinforcing member, a fuel cell, a water electrolysis device, a metallized film, a current collecting foil, a secondary battery, a film capacitor, an electrical insulating paper for a motor, and a motor.

[0002] As electrical and electronic devices, battery materials, machine parts, and automotive parts become more functional and precise, the quality requirements for the components used are becoming stricter. For example, strict quality requirements are required for fuel cells, water electrolysis devices, capacitor substrate films, and current collector foil substrate films. These components often require processing steps such as laminating the base film with other materials or heat treatment.

[0003] Polyarylene sulfide has excellent properties such as heat resistance, hydrolysis resistance, flame retardancy, rigidity, chemical resistance, electrical insulation, and low moisture absorption, making it particularly suitable for use in electrical and electronic devices, battery materials, machine parts, and automotive parts. In recent years, solid polymer fuel cells and water electrolysis devices, which have been developed with a view to achieving carbon neutrality, are composed of multiple stacked cells. These devices are equipped with a reinforcing material that is hermetically bonded to the electrolyte membrane to prevent wrinkles and deformation during processing, mechanically reinforce the electrolyte membrane's periphery, and prevent fuel gas and oxygen gas from leaking from the interface with the electrolyte membrane. Furthermore, a reinforcing material that has the required mechanical strength and hydrolysis resistance even at operating temperatures is preferred. Polyarylene sulfide films, such as polyphenylene sulfide (hereinafter sometimes abbreviated as PPS), are being used as electrolyte membrane reinforcing materials, taking advantage of their high hydrolysis resistance.

[0004] To date, a technology for reinforcing members for solid electrolyte membranes in which the metal element-containing components of PPS resin have been reduced has been disclosed (Patent Document 1). Also, a technology for PPS film that improves quality by controlling residence time and oxygen concentration has been disclosed (Patent Document 2). Another technology for reducing thickness variation in the longitudinal direction by alloying with other thermoplastic resins has also been disclosed (Patent Document 3).

[0005] JP 2016-219136 A JP 2021-088174 A JP 2022-151606 A

[0006] Due to the molecular structure unique to this highly durable resin, PPS film is prone to thickness variations and orientation irregularities during biaxial stretching. Furthermore, this film is prone to deformation and warping during lamination and processing, which can lead to handling problems and misalignment due to thickness variations when stacking hundreds of layers.

[0007] The techniques described in Patent Documents 1 and 2 are insufficient to improve thickness variations and orientation unevenness of PPS, and have the problem of gaps occurring when many PPS sheets are stacked together. Also, the technique described in Patent Document 3 reduces thickness variations in the longitudinal direction, but is insufficient to improve thickness variations and orientation unevenness across the width, and has the problem of gaps occurring when many PPS sheets are stacked together.

[0008] The object of the present invention is to solve the above-mentioned problems, that is, to provide a biaxially oriented polyarylene sulfide film that can suppress warping during processing and has excellent pressure uniformity when a large number of films are stacked and pressed together.

[0009] The present invention is configured as follows. (1) A biaxially oriented film containing a polyarylene sulfide resin as a main constituent, wherein the thickness variation in the film width direction over a 300 mm width centered at the center of the film width direction is 0.5% or more and 10.0% or less, the orientation angle from the film longitudinal direction is greater than -35° and less than 35°, greater than -90° and less than -55°, or greater than 55° and less than 90°, and the difference between the maximum and minimum values ​​of the orientation angle is 0.5° or more and 20.0° or less. (Method for measuring the orientation angle from the film longitudinal direction) The orientation angle from the film longitudinal direction was evaluated at a frequency of 15 GHz using a microwave transmission molecular orientation meter MOA-6015 (manufactured by Oji Scientific Instruments Co., Ltd.). The film was cut into a piece 300 mm in the width direction x 30 mm in the longitudinal direction, and the cut film sample was further cut every 30 mm in the width direction to obtain 10 film samples each measuring 30 mm in the width direction x 30 mm in the longitudinal direction. The orientation angle is determined with the longitudinal direction of the film as the 0° direction of the measuring instrument (the orientation angle measured ranges from -90° to 90°). The average of the orientation angles at 10 measurement points in the width direction is defined as the orientation angle from the longitudinal direction of the film, and the difference between the maximum and minimum orientation angles at the 10 measurement points in the width direction is determined. (2) The biaxially oriented polyarylene sulfide film according to (1), wherein the orientation angle is greater than -30° and less than 30°, or greater than -90° and less than -60°, or greater than 60° and less than 90°. (3) The biaxially oriented polyarylene sulfide film according to (1) or (2), wherein the thickness variation in the film width direction is 0.5% or more and 6.0% or less over a 300 mm width centered at the center of the film width direction. (4) The biaxially oriented polyarylene sulfide film according to any one of (1) to (3), wherein the modulus of elasticity measured at 130°C is 1.0 GPa or more in the longitudinal and width directions. (5) A biaxially oriented polyarylene sulfide film according to any one of (1) to (4), in which the central surface average roughness SRa of at least one surface is 10 nm or more and 100 nm or less. (6) A biaxially oriented polyarylene sulfide film according to any one of (1) to (5), in which the calcium ion concentration is 10 ppm by mass or less. (Method for measuring calcium ion concentration) The film is cut with ceramic scissors to a weight of 4 g, and used as an analysis sample.The surface is washed with ultrapure water, and then the film is heated and extracted for 2 hours in 100 mL of a pre-boiled 5% by mass nitric acid solution. The extracted solution is qualitatively analyzed by inductively coupled plasma mass spectrometry (ICP-MS) to determine the calcium ion concentration per unit mass of the sample. ICP-MS analyzer: Agilent Technologies Agilent 8800. (7) The biaxially oriented polyarylene sulfide film according to any one of (1) to (6), wherein the differential molecular weight distribution curve measured by gel permeation chromatography has a vertical axis value (dw / dLogM) of 0.10 or more and 0.60 or less when the horizontal axis value (LogM) is 5.2. (Method for Preparing a Differential Molecular Weight Distribution Curve) A differential molecular weight distribution curve is prepared in accordance with JIS K7252 (2016). Specifically, 5 mL of 1-chloronaphthalene (1-CN) is added to 5 mg of sample, and the mixture is gently stirred at 210 to 220°C for 20 minutes, followed by visual confirmation that the sample has dissolved. The mixture is then filtered using a 0.5 μm filter. A GPC curve is obtained by measurement under the conditions shown below. The obtained GPC curve is converted using a molecular weight calibration curve prepared by approximating the logarithm of the molecular weight of polystyrene with a cubic equation for the elution time, and the weight fraction is calculated by normalizing the peak area to 1. Note that the molecular weight is a relative value based on polystyrene, and a differential molecular weight distribution curve is prepared by plotting the logarithm of the molecular weight M on the horizontal axis and the weight fraction (dw / dLogM) on the vertical axis. From the obtained differential molecular weight distribution curve, the vertical axis value (dw / dLogM) is read when the horizontal axis value (LogM) is 5.2.Apparatus: High-temperature GPC apparatus (instrument No. GPC-H-2, PL-GPC220 manufactured by Polymer Laboratories) Detector: Differential refractive index detector RI Data interval: every 0.5 seconds Column: Shodex UT-G (guard column) PLgel 10 m MIXED-B-LS (2 columns) (8.0 mm x 30 cm, manufactured by Polymer Laboratories) Solvent: 1-chloronaphthalene Flow rate: 0.7 mL / min Column temperature: 210°C Injection volume: 0.200 mL Standard sample: Monodisperse polystyrene manufactured by Tosoh (8) The biaxially oriented polyarylene sulfide film according to any one of (1) to (7), wherein in a differential molecular weight distribution curve measured by gel permeation chromatography, the vertical axis value (dw / dLogM) is 0.10 or more and 0.40 or less when the horizontal axis value (LogM) is 4.0. (9) The biaxially oriented polyarylene sulfide film according to any one of (1) to (8), wherein in a differential molecular weight distribution curve measured by gel permeation chromatography, the vertical axis value (dw / dLogM) is 0.01 or more and 0.25 or less when the horizontal axis value (LogM) is 5.5. (10) The biaxially oriented polyarylene sulfide film according to any one of (1) to (9), wherein the resonance parameter (Q value) is 4600 or more and 5200 or less. (11) The biaxially oriented polyarylene sulfide film according to any one of (1) to (10), having a minute endothermic peak temperature (T-meta) determined by differential scanning calorimetry (DSC) of 200°C or higher (melting point -20°C) or lower. (12) A biaxially oriented polyarylene sulfide film roll obtained by winding up the biaxially oriented polyarylene sulfide film according to any one of (1) to (11). (13) An electrolyte membrane reinforcing member having the biaxially oriented polyarylene sulfide film according to any one of (1) to (11). (14) An electrolyte membrane reinforcing member having a biaxially oriented polyarylene sulfide film satisfying conditions (a) and (b). (a) The calcium ion concentration is 10 ppm by mass or less. (b) In a differential molecular weight distribution curve measured by gel permeation chromatography, the value on the vertical axis (dw / dLogM) is 0.15 or more and 0.60 or less when the value on the horizontal axis (LogM) is 5.2.(15) An electrolyte membrane reinforcing member according to (14), in which, in a differential molecular weight distribution curve measured by gel permeation chromatography, the vertical axis value (dw / dLogM) is 0.10 or more and 0.40 or less when the horizontal axis value (LogM) is 4.0. (16) An electrolyte membrane reinforcing member according to (14) or (15), in which, in a differential molecular weight distribution curve measured by gel permeation chromatography, the vertical axis value (dw / dLogM) is 0.01 or more and 0.25 or less when the horizontal axis value (LogM) is 5.5. (17) An electrolyte membrane reinforcing member in the form of a rectangular frame having an opening, in which at least one film layer constituting the electrolyte membrane reinforcing member satisfies conditions (A) and (B). (A) The orientation angle is greater than -35° and less than 35°, greater than -90° and less than -55°, or greater than 55° and less than 90°. (B) The difference between the maximum and minimum values ​​of the orientation angle is 0.5° or more and 20° or less. (Method for Measuring the Orientation Angle of an Electrolyte Membrane Reinforcement Member) Evaluation is performed using a microwave transmission molecular orientation analyzer MOA-6015 (manufactured by Oji Scientific Instruments Co., Ltd.) at a frequency of 15 GHz. One of the outer peripheral directions of the rectangular frame-shaped electrolyte membrane reinforcing member is set as the 0° direction of the measuring instrument, and the film layer frame-shaped portion is cut along the outer periphery into pieces measuring 30 mm x 30 mm on all four sides. The orientation angles of the film layers removed from the cut samples are determined (the measured orientation angles range from -90° to 90°). The average value of the orientation angles of the obtained film layer frame-shaped portions is defined as the orientation angle of the layer to be measured, and the difference between the maximum and minimum values ​​of the orientation angle of the film layer frame-shaped portion is determined. (18) An electrolyte membrane reinforcing member according to (17), in which the thickness variation when measuring a film layer satisfying conditions (A) and (B) at 10 mm intervals is 0.5% or more and 10.0% or less. (19) An electrolyte membrane reinforcing member according to (17) or (18), in which the tan δ peak temperature of the film layer satisfying the conditions (A) and (B) as determined by dynamic viscoelasticity measurement is 120° C. or higher and 160° C. or lower. (20) An electrolyte membrane reinforcing member according to any one of (17) to (19), in which the film layer satisfying the conditions (A) and (B) contains a polyarylene sulfide resin as a main constituent. (21) A fuel cell having the electrolyte membrane reinforcing member according to any one of (13) to (20).(22) A water electrolysis device having the electrolyte membrane reinforcing member according to any one of (13) to (20). (23) A metallized film obtained by providing a metal layer on at least one surface of the biaxially oriented polyarylene sulfide film according to any one of (1) to (11). (24) A current collector foil obtained by providing a metal layer on at least one surface of the biaxially oriented polyarylene sulfide film according to any one of (1) to (11). (25) A secondary battery using the current collector foil according to (24). (26) A film capacitor using the metallized film according to (23). (27) Electrical insulating paper for motors using the biaxially oriented polyarylene sulfide film according to any one of (1) to (11). (28) A motor using the electrical insulating paper for motors according to (27).

[0010] The present invention can provide a biaxially oriented polyarylene sulfide film that can suppress warping during processing and has excellent pressure uniformity when a large number of films are stacked and pressed together. The biaxially oriented polyarylene sulfide film of the present invention can be suitably used as various parts for automobiles and electric and electronic materials, circuit substrates, heat-resistant tape substrates, films for toner stirrers for printing, and release films, and can be particularly suitably used as electrolyte membrane reinforcing members for fuel cells and water electrolysis devices, which have strict flatness requirements, as well as film capacitors and current collector foil substrates.

[0011] 1 is a top view of an electrolyte membrane reinforcing member having an opening according to an embodiment of the present invention, and FIG. 2 is a schematic oblique overhead view showing an example of the configuration of an electrolyte membrane reinforced by a film and an adhesive layer.

[0012] A preferred embodiment of the present invention is a biaxially oriented film containing a polyarylene sulfide resin as a main constituent, wherein the thickness variation in the film width direction over a 300 mm width centered at the center of the film width direction is 0.5% or more and 10.0% or less, the orientation angle from the film longitudinal direction is more than -35° and less than 35°, -90° or more and less than -55°, or more than 55° and less than 90°, and the difference between the maximum and minimum orientation angles is 0.5° or more and 20.0° or less. According to this embodiment, a biaxially oriented polyarylene sulfide film can be provided which has small thickness variation and orientation unevenness and excellent processability.

[0013] In the present invention, the biaxially oriented polyarylene sulfide film is preferably a biaxially oriented film containing a polyarylene sulfide resin (hereinafter sometimes abbreviated as PAS resin) as a main constituent component. The film can be obtained by melt-molding a resin composition containing a PAS resin as a main constituent component into a sheet, biaxially stretching the sheet, and heat-setting the sheet.

[0014] In the present invention, "containing a PAS resin as a main constituent" means that the PAS resin is contained in an amount of 90% by mass or more. It is more preferable that the PAS resin is contained in an amount of 95% by mass or more. By containing a PAS resin in an amount of 90% by mass or more, excellent heat resistance, hydrolysis resistance, chemical resistance, electrical properties, and mechanical properties can be exhibited.

[0015] The biaxially oriented polyarylene sulfide film of the present invention may contain thermoplastic resins other than PAS resin, as long as the content is less than 10% by mass and does not impair the effects of the present invention. For example, it may contain various polymers such as polyamide, polyetherimide, polyethersulfone, polysulfone, polyphenylene ether, polyphenylsulfone, polyester, polyarylate, polyamideimide, polycarbonate, polyolefin, polyetheretherketone, and fluororesin, as well as blends containing at least one of these polymers. Excessive content of components other than PAS resin may lead to peeling, cracking, voids, and other problems at the interface with the PAS resin, accelerating deterioration and potentially resulting in poor durability and barrier properties. Furthermore, recycled PAS resin raw materials may also be used in the present invention, as long as the effects of the invention are not impaired.

[0016] The PAS resin used in the present invention is a copolymer having a repeating unit of -(Ar-S)-. Examples of Ar (arylene group) include units represented by the following formulas (A) to (K).

[0017]

[0018] (R1 and R2 are substituents selected from hydrogen, alkyl groups, alkoxy groups, and halogen groups, and R1 and R2 may be the same or different.)

[0019] As the repeating unit, the p-arylene sulfide unit represented by the above formula (A) is preferred, and the p-phenylene sulfide unit is particularly preferred from the viewpoints of film properties and economic efficiency. Representative examples of PAS resins having these repeating units include polyphenylene sulfide, polysulfone, polyethersulfone, polyphenylene sulfide sulfone, and polyphenylene sulfide ketone.

[0020] The PAS resin used in the present invention preferably comprises p-phenylene sulfide units represented by the following structural formula as the main structural unit, in an amount of 80.0 mol % to 99.9 mol % of all repeating units. This is more preferably 90.0 mol % to 99.9 mol %, and most preferably 95.0 mol % to 99.9 mol %. By using the above composition, high crystallinity and orientation can be maintained, and excellent heat resistance and chemical resistance can be achieved.

[0021]

[0022] Furthermore, it can also be copolymerized with copolymerization units in an amount of 0.01 mol % or more and 20.00 mol % or less of the repeating units.

[0023] Preferred copolymer units include the following:

[0024]

[0025]

[0026]

[0027] where X is alkylene, CO, SO ２ Indicates the unit.

[0028]

[0029]

[0030] Here, R represents an alkyl, nitro, phenylene, or alkoxy group.

[0031] There is no particular limitation on the type of copolymer, but a random copolymer is preferred.

[0032] In the present invention, the polyarylene sulfide film is preferably a biaxially oriented film. By making the polyarylene sulfide film a biaxially oriented film, it is possible to improve mechanical strength, flatness, and productivity and reduce thickness variation. When used as an automotive component, a battery component, various electrical and electronic material parts, and industrial packaging, it is preferable to have undergone a biaxial stretching treatment in order to improve the film properties. As exemplified in the production method described below, examples of the biaxial stretching treatment include sequential biaxial stretching (a stretching method that combines stretching in one direction at a time, such as a method in which stretching in the longitudinal direction is followed by stretching in the width direction), simultaneous biaxial stretching (a method in which stretching in the longitudinal direction and the width direction is performed simultaneously), or a combination thereof. Here, "the polyarylene sulfide film is a biaxially oriented film" means that the resonance parameter (Q value) of the polyarylene sulfide film, measured using a molecular orientation meter (MOA-6015, manufactured by Oji Scientific Instruments), is 4300 or more.

[0033] The biaxially oriented polyarylene sulfide film of the present invention preferably has a resonance parameter (Q value) of 4600 or more and 5200 or less. In the present invention, the Q value is measured using a molecular orientation meter (MOA-6015, manufactured by Oji Scientific Instruments) and is the average value of 10 measurements of the parameter (Q value) indicating the sharpness of the resonance of the biaxially oriented polyarylene sulfide film, and the detailed measurement method is as described in the Examples. The Q value increases as the orientation of the molecular chains in the film increases. A resonance parameter (Q value) within the above range indicates sufficient orientation of the molecular chains, and is preferable because the arrangement of the molecular chains improves thickness variation. A resonance parameter (Q value) of less than 4600 is insufficient in orientation, resulting in large thickness variation and potentially poor flatness and processability when used as a fuel cell or water electrolysis device. If the resonance parameter (Q value) exceeds 5200, it indicates that the molecular chains are extremely oriented, and the tensile elongation of the film decreases, which may cause breakage due to the tension during processing in the coating process or punching process, resulting in a decrease in yield. The resonance parameter (Q value) is more preferably 4700 or more, even more preferably 4800 or more, and particularly preferably 4900 or more. The resonance parameter (Q value) is more preferably 5000 or less. In the film formation conditions described below, a high stretch ratio tends to increase the resonance parameter (Q value), and a high stretching temperature tends to decrease the resonance parameter (Q value).

[0034] A preferred embodiment of the present invention is a biaxially oriented polyarylene sulfide film roll obtained by winding a biaxially oriented polyarylene sulfide film. The biaxially oriented polyarylene sulfide film roll of the present invention preferably has a film width of 300 mm or more. The biaxially oriented polyarylene sulfide film roll may be an intermediate product roll obtained by winding the film immediately after production, or may be a product roll obtained by slitting the intermediate product roll.

[0035] The biaxially oriented polyarylene sulfide film of the present invention may be a single film or a composite film. Examples of composite films include laminate films of two or more layers. For example, the biaxially oriented polyarylene sulfide film of the present invention may be a two-layer laminate film consisting of Layer A / Layer B, or a three-layer laminate film consisting of Layer A / Layer B / Layer A, with the biaxially oriented polyarylene sulfide film of the present invention as the surface layer (Layer A). When used as a reinforcing member for a fuel cell or water electrolysis device, a capacitor, a current collecting foil, or an electrical insulating paper for a motor, from the viewpoints of hydrolysis resistance and mechanical properties, it is preferable that all layers contain a polyarylene sulfide resin as a main constituent.

[0036] In a preferred embodiment of the biaxially oriented polyarylene sulfide film of the present invention, the thickness variation in the film width direction is 0.5% to 10.0% in a 300 mm width centered at the center of the film width direction. By keeping the thickness variation within this range, it is possible to suppress misalignment due to thickness variation when the film is used as a stacked electrolyte membrane reinforcing member. That is, by adopting the above embodiment, it is possible to achieve excellent pressure uniformity when multiple films are stacked and pressed together. By keeping the thickness variation in the film width direction to 10.0% or less, it is possible to prevent deterioration of flatness and poor stackability as an electrolyte membrane reinforcing member when the film is laminated with other materials or heat processed. Furthermore, if the thickness variation in the film width direction is less than 0.5%, in the film production process, by increasing the longitudinal stretching ratio before transverse stretching in the film production process described below, stress propagation during transverse stretching can be uniformed and thickness variation in the film width direction can be reduced. However, this requires an extremely high stretching ratio, which may deteriorate film formability. The thickness variation in the film width direction is more preferably 1.0% or more. The thickness variation in the film width direction is more preferably 9.0% or less, even more preferably 8.0% or less, and most preferably 6.0% or less. Generally, biaxially oriented polyarylene sulfide films have low inter-molecular chain interactions due to their resin properties, making it difficult to transmit stress during stretching, making it difficult to reduce thickness variation. However, under the film-forming conditions described below, a high stretch ratio and a high film resonance parameter (Q value) tend to reduce thickness variation in the film width direction, and a low heat-setting temperature also tends to reduce thickness variation. With regard to the molecular weight distribution of the raw material, a high content of low-molecular-weight components tends to increase stretchability during film formation and reduce thickness variation. Taking these trends into consideration, the thickness variation in the present invention can be adjusted to the above-mentioned range.

[0037] In a preferred embodiment of the biaxially oriented polyarylene sulfide film of the present invention, the thickness variation at the widthwise center over 300 mm in the longitudinal direction of the film is 0.5% or more and 10.0% or less. By setting the thickness variation in the longitudinal direction of the film within the above range, the film can be used as an electrolyte membrane reinforcing member, similar to the film width direction, and misalignment due to thickness variation when stacked can be suppressed. By setting the thickness variation in the longitudinal direction of the film to 10.0% or less, deterioration in flatness and poor stackability as an electrolyte membrane reinforcing member can be prevented when the film is laminated with other materials or subjected to heat processing. Furthermore, by setting the thickness variation in the longitudinal direction of the film to 0.5% or more, it is not necessary to extremely increase the longitudinal stretching ratio in the film production process described below, and film production properties are favorable. The thickness variation in the longitudinal direction of the film is more preferably 1.0% or more. The thickness variation in the film longitudinal direction is more preferably 9.0% or less, even more preferably 8.0% or less, and most preferably 6.0% or less. Regarding the film-forming conditions described below, a higher longitudinal stretching ratio tends to reduce the thickness variation in the film longitudinal direction, and a lower heat-setting temperature also tends to reduce the thickness variation. Regarding the molecular weight distribution of the raw material, an increase in the content of high-molecular-weight components tends to improve the efficiency of stress propagation during stretching during film formation, thereby reducing the thickness variation in the film thickness direction. Taking these trends into consideration, the thickness variation in the present invention can be adjusted to the above-mentioned range.

[0038] In the present invention, the width direction refers to the direction along the short side of the film roll, and the longitudinal direction of the film refers to the direction perpendicular to the width direction, i.e., the direction along the long side of the film roll. On the other hand, when the film is in a cut sheet form and the longitudinal direction cannot be determined, one of the directions is set to 0°, and the elastic modulus is measured by changing the direction in 10° increments from -90° to 90° within the film plane, and the direction with the highest elastic modulus is taken as the longitudinal direction. Next, lines are drawn in the longitudinal direction and perpendicular to the longitudinal direction so as to pass through the center of gravity of a sample cut into a 150 mm x 150 mm square, and the orientation angles of the ends (four locations) on these lines and the center of gravity are evaluated, and the direction with the larger difference between the maximum and minimum orientation angles of both ends and the center on the line is taken as the width direction.

[0039] In a preferred embodiment of the biaxially oriented polyarylene sulfide film of the present invention, the orientation angle from the longitudinal direction of the film in a 300 mm width centered at the center of the film's width direction is greater than -35° and less than 35°, greater than -90° and less than -55°, or greater than 55° and less than 90°. An orientation angle from the longitudinal direction of the film within the above range indicates small deviation in orientation, which reduces warping and deformation during lamination with other materials and improves stackability as an electrolyte membrane reinforcing member. If the orientation angle from the longitudinal direction of the film is greater than -55° and less than -35°, or greater than 35° and less than 55°, deviation of the orientation axis becomes large, which may result in warping and deformation during lamination with other materials. The orientation angle from the longitudinal direction of the film is more preferably greater than -30° and less than 30°, -90° or greater but less than -55°, or greater than 55° and less than 90°, even more preferably greater than -30° and less than 30°, or greater than -90° or greater but less than -60°, or greater than 60° and less than 90°, particularly preferably greater than -25° and less than 25°, or greater than -90° or greater but less than -65°, or greater than 65° and less than 90°, even more preferably greater than -20° and less than 20°, or greater than -90° or greater but less than -70°, or greater than 70° and less than 90°, and most preferably greater than -20° and less than 20°. Under the film-forming conditions described below, the orientation angle from the longitudinal direction tends to approach 0° when the longitudinal stretching ratio is high, and tends to approach -90° or 90° when the transverse stretching ratio is high. Furthermore, when the heat setting temperature is low, the orientation angle from the longitudinal direction tends to approach -90°, 0°, or 90°.

[0040] In a preferred embodiment of the biaxially oriented polyarylene sulfide film of the present invention, the difference between the maximum and minimum orientation angles in a 300 mm width centered on the center of the film in the width direction is 0.5° or more and 20.0° or less. When the difference between the maximum and minimum orientation angles is within the above range, orientation unevenness is small, and warping can be reduced when performing heat processing for lamination with an electrolyte membrane reinforcing member, etc., facilitating stack processing. To produce a film with a difference between the maximum and minimum orientation angles of less than 0.5°, the film production process can be performed by only stretching without heat setting, or by performing offline heat setting, thereby eliminating film bowing and producing a film with little orientation unevenness. However, this may result in deterioration of film formability or significant deformation during heat processing, which may cause warping. When the difference between the maximum and minimum orientation angles exceeds 20.0°, warping during lamination processing may be significant, resulting in a decrease in flatness.

[0041] The difference between the maximum and minimum orientation angles is more preferably 3.0° or more, and even more preferably 5.0° or more. The difference is more preferably 18.0° or less, and even more preferably 15.0° or less. Generally, biaxially oriented polyarylene sulfide films have high thermal responsiveness due to their resin properties, and are susceptible to bowing during heat setting and relaxation treatments, making it difficult to reduce the difference in orientation angle. However, under the film-forming conditions described below, the difference tends to increase when the longitudinal stretching ratio is high, and the difference tends to increase when the heat setting temperature is high. Furthermore, the difference tends to decrease when the relaxation amount per relaxation treatment is reduced. Furthermore, the difference tends to decrease when the high molecular weight component in the molecular weight distribution is increased. Furthermore, the difference tends to decrease when the widthwise stretching is performed twice. Taking these trends into consideration, the difference in orientation angle in the present invention can be adjusted to the above-mentioned range.

[0042] The biaxially oriented polyarylene sulfide film of the present invention preferably has a modulus of elasticity measured at 130°C of 1.0 GPa or more in both the longitudinal and width directions. A modulus of elasticity measured at 130°C within the above range is preferable because it maintains rigidity during heat processing of the electrolyte membrane, suppresses deformation, and maintains flatness. The modulus of elasticity measured at 130°C in both the longitudinal and width directions is more preferably 1.2 GPa or more, and even more preferably 1.4 GPa or more. There is no particular upper limit to the modulus of elasticity measured at 130°C, but the modulus of elasticity measured at 130°C in both the longitudinal and width directions is preferably 4.0 GPa or less, and more preferably 3.5 GPa or less. Within this range, orientation does not become too high, and the modulus of elasticity and heat shrinkage of the film can be controlled. Regarding the elastic modulus measured at 130°C, when the longitudinal stretching ratio is high under the film-forming conditions described below, the elastic modulus measured at 130°C tends to be high in both the longitudinal and width directions; when the transverse stretching ratio is high, the elastic modulus measured at 130°C in the width direction tends to be high; and when the heat-setting temperature is low, the elastic modulus measured at 130°C tends to be high.

[0043] The weight-average molecular weight of the biaxially oriented polyarylene sulfide film of the present invention is preferably 45,000 or more, more preferably 50,000 or more, and even more preferably 60,000 or more. A weight-average molecular weight of 45,000 or more tends to provide sufficient mechanical strength for the biaxially oriented film and reduces thickness variation, which is preferable. There is no particular upper limit for the weight-average molecular weight, but a preferred range is 150,000 or less, more preferably 120,000 or less, and even more preferably 100,000 or less. By keeping it within this range, the tensile elongation and durability of the biaxially oriented film can be controlled. The weight-average molecular weight is a value measured using a gel permeation chromatograph (hereinafter sometimes abbreviated as GPC) equipped with a differential refractive index detector. More specifically, the value was calculated using GPC with a column temperature of 210°C and a detector temperature of 210°C, 1-chloronaphthalene as the eluent, at a flow rate of 1.0 mL / min, using a 1-chloronaphthalene solution with a PAS concentration of 0.1% by mass, and polystyrene as the standard substance.

[0044] The biaxially oriented polyarylene sulfide film of the present invention preferably has a peak in the logarithm Log M of the molecular weight M range of 4.0 to 6.0 in a differential molecular weight distribution curve measured by gel permeation chromatography described below. When the logarithm is in this range, the viscosity during melt extrusion can be ensured, and the tensile elongation and durability of the biaxially oriented film can be controlled.

[0045] In the biaxially oriented polyarylene sulfide film of the present invention, in the differential molecular weight distribution curve measured by gel permeation chromatography described below, the vertical axis value (dw / dLogM) of the differential molecular weight distribution curve when the logarithm LogM of the molecular weight M is 5.2 is preferably 0.10 or more and 0.60 or less. This range indicates that a large number of molecular chains with high molecular weight are contained, and the number of components that become stress propagation points during width direction stretching increases, thereby reducing orientation variation. If the vertical axis value (dw / dLogM) of the differential molecular weight distribution curve when the logarithm LogM of the molecular weight M is 5.2 is less than 0.10, there is a risk of the number of components that become stress propagation points during width direction (TD) stretching becoming too few, resulting in increased thickness variation. When the logarithm LogM of the molecular weight M is 5.2, the vertical axis value (dw / dLogM) of the differential molecular weight distribution curve is greater than 0.60, which increases the viscosity during melt extrusion due to the high molecular weight component content, resulting in large thickness fluctuations during extrusion molding and a risk of large thickness variations in the biaxially stretched film. From the above viewpoints, the vertical axis value (dw / dLogM) of the differential molecular weight distribution curve when the logarithm LogM of the molecular weight M is 5.2 is more preferably 0.15 or more, and even more preferably 0.20 or more. When the logarithm LogM of the molecular weight M is 5.2, the vertical axis value (dw / dLogM) of the differential molecular weight distribution curve is more preferably 0.55 or less.

[0046] In the biaxially oriented polyarylene sulfide film of the present invention, the value of the vertical axis of the differential molecular weight distribution curve (dw / dLogM) when the logarithm LogM of the molecular weight M is 4.0, measured by gel permeation chromatography (described later), is preferably 0.10 or more and 0.40 or less. The value of the vertical axis of the differential molecular weight distribution curve indicates the content of low molecular weight components, and if this value is within the above range, it is preferable because it can be used as an electrolyte membrane reinforcement member while reducing the low molecular weight components, thereby improving transportability during processing. If it is less than 0.10, there will be few low molecular weight components to disperse stress when heat and tension are applied during transport such as coating, and stress concentration will cause deformation, which may deteriorate transportability. If the value of the vertical axis of the differential molecular weight distribution curve (dw / dLogM) when the logarithm LogM of the molecular weight M is 4.0 is greater than 0.40, the heat resistance of the biaxially oriented polyarylene sulfide may be reduced. From the above viewpoints, the value on the vertical axis of the differential molecular weight distribution curve (dw / dLogM) when the logarithm LogM of the molecular weight M is 4.0 is more preferably 0.15 or more, and even more preferably 0.20 or more. The value on the vertical axis of the differential molecular weight distribution curve (dw / dLogM) when the logarithm LogM of the molecular weight M is 4.0 is more preferably 0.35 or less, and even more preferably 0.30 or less.

[0047] In the biaxially oriented polyarylene sulfide film of the present invention, in the differential molecular weight distribution curve measured by gel permeation chromatography described below, the vertical axis value of the differential molecular weight distribution curve when the logarithm LogM of the molecular weight M is 5.5 (dw / dLogM) is preferably 0.01 or more and 0.25 or less. This range indicates the inclusion of long molecular chain components, and the entanglement of the polymer becomes the stress propagation point during stretching, allowing for uniform stretching, thereby reducing orientation variation and thickness variation. Furthermore, the inclusion of long molecular chain components reduces the fluidity of the molecular chains and increases rigidity, which may suppress deformation during the aging process after adhesive application or during heating or pressure processing for a certain period of time, thereby improving processability. When the logarithm LogM of the molecular weight M is 5.5, the vertical axis value (dw / dLogM) of the differential molecular weight distribution curve is less than 0.01, which means that there are few entangled components that serve as stress propagation points during stretching, which may result in large thickness variations, or wrinkles or warping due to deformation during processing. When the logarithm LogM of the molecular weight M is 5.5, the vertical axis value (dw / dLogM) of the differential molecular weight distribution curve is greater than 0.25, which means that there are many entangled components of molecular chains, which may result in a high viscosity during melt extrusion, which may result in large thickness variations during extrusion molding, which may result in large thickness variations as a biaxially stretched film. From the above viewpoints, the vertical axis value (dw / dLogM) of the differential molecular weight distribution curve when the logarithm LogM of the molecular weight M is 5.5 is more preferably 0.02 or more, and even more preferably 0.05 or more. The value on the vertical axis of the differential molecular weight distribution curve (dw / dLogM) when the logarithm LogM of the molecular weight M is 5.5 is more preferably 0.20 or less.

[0048] The biaxially oriented polyarylene sulfide film of the present invention preferably has a center surface average roughness SRa of 10 nm or more and 100 nm or less on at least one film surface. The center surface average roughness SRa is a parameter of three-dimensional surface roughness and means the average roughness at the center surface when the surface roughness curve is approximated by a sine curve. The center surface average roughness SRa is a three-dimensional extension of the two-dimensional roughness parameter center line average roughness (Ra) described in JIS B0601-1994, and is calculated by dividing the volume enclosed by the surface profile curve and the center surface by the measured area. When the center surface is the XY plane, the vertical direction is the Z axis, and the measured surface profile curve is f(x, y), it is defined by the following mathematical formula (i): where Lx is the measured length in the X direction, and Ly is the measured length in the Y direction.

[0049]

[0050] By setting the SRa within the above range, a film with excellent running properties can be obtained. If the SRa of the film surface is less than 10 nm, the surface is smooth, which increases friction during transport and may result in reduced running properties. If the SRa of the film surface exceeds 100 nm, the surface becomes uneven and slippery, which may cause slippage during stack processing. The SRa is more preferably 20 nm or more and 50 nm or less. The surface roughness tends to increase by adding particles or other resins contained in the film, which will be described later. The SRa is evaluated by the method described later.

[0051] To control the surface roughness of the film, there is a method of adding inert particles within a range that does not impair the effects of the present invention. Examples of inert particles referred to here include inorganic fillers such as silica, alumina, calcium carbonate, barium carbonate, barium titanate, barium sulfate, calcium silicate, magnesium oxide, titanium oxide, and zinc oxide, and particles of organic polymer compounds that do not melt at 300 ° C (for example, cross-linked polystyrene). Adding inert particles can improve the slipperiness of the film in the film stretching process, suppress the occurrence of wrinkles when the film runs between rolls, and maintain the surface irregularities of the film even when the temperature of heat setting following transverse stretching is increased, thereby suppressing surface scratches and improving running properties.

[0052] The biaxially oriented polyarylene sulfide film of the present invention preferably has a calcium ion content of 10 ppm by mass or less when extracted with boiling nitric acid. If the calcium ion content exceeds 10 ppm by mass, when the film is used as a reinforcing member for a fuel cell or water electrolysis device, calcium element may be eluted under the high temperature, high humidity, and strong acidity conditions within the fuel cell, causing contamination of the fuel cell catalyst and gas diffusion layer, and reducing the power generation capacity of the fuel cell. The calcium ion content is more preferably 5 ppm by mass or less, and even more preferably 3 ppm by mass or less. The calcium ion content can be controlled within the above range by using a polyarylene sulfide resin with low impurities, optimizing drying and extrusion conditions, and implementing a comprehensive design including lubricating particles to improve the quality of the film used. The calcium ion content is evaluated using the method described below.

[0053] From the viewpoint of further improving thermal stability, the biaxially oriented polyarylene sulfide film of the present invention preferably has a minute endothermic peak temperature (T-meta) determined by differential scanning calorimetry (DSC) of 200°C or higher (melting point -20°C) or lower. The minute endothermic peak temperature (T-meta) in the present invention indicates that the film has undergone thermal history. When the T-meta is within the above range, bowing of the film during the film-forming process can be controlled, and a film with excellent flatness and processability can be obtained. Furthermore, when the T-meta is lower than 200°C, the thermal history is low, and the heat during processing may deteriorate the flatness and processability. When the T-meta exceeds (Tm -20°C), bowing of the film increases, and processability may be impaired. The T-meta is more preferably 210°C or higher and 260°C or lower, even more preferably 210°C or higher and 250°C or lower, and particularly preferably 215°C or higher and 240°C or lower. The T-meta can be controlled by the heat setting temperature. While the T-meta varies depending on the film forming machine and film formation speed, the higher the heat setting temperature, the higher the T-meta. The melting point (Tm) is preferably 275°C or higher and 290°C or lower, and more preferably 283°C or higher and 290°C or lower.

[0054] The thickness of the biaxially oriented polyarylene sulfide film of the present invention is not particularly limited, but from the viewpoint of film formability, a film thickness of 0.5 μm or more and 300 μm or less is preferred. For electrolyte membrane reinforcing members and electrical insulating paper for motors, a film thickness of 10 to 150 μm is more preferred from the viewpoint of handleability, 20 to 125 μm is even more preferred, and 35 to 120 μm is most preferred. Furthermore, for applications in film capacitors and battery current collector foil substrates such as lithium ion secondary batteries, a film thickness of 0.5 μm or more and 15 μm or less is preferred from the viewpoint of a balance between durability and thinning, with a thickness of more preferably 9.0 μm or less, and even more preferably 6.0 μm or less. Film thickness can be measured using a known micrometer, as will be described in detail below.

[0055] The method for producing a biaxially oriented polyarylene sulfide film of the present invention will be described using as an example a film production method in which polyphenylene sulfide resin (hereinafter sometimes abbreviated as PPS resin) is used as the polyarylene sulfide resin, but the present invention is not limited to this example.

[0056] Sodium sulfide and p-dichlorobenzene are blended and reacted under high temperature and pressure in an amide-based polar solvent such as N-methyl-2-pyrrolidone (NMP). If necessary, copolymerization components such as m-dichlorobenzene or trihalobenzene can be added. Caustic potassium or an alkali metal carboxylate is added as a polymerization degree modifier, and the polymerization reaction is carried out at 200 to 290°C. The molecular weight of the resulting PPS resin can be controlled by known methods (e.g., International Publication No. 2007 / 108384). After polymerization, the polymer is cooled, slurried in water, and filtered to obtain a wet granular polymer. This granular polymer is then added to an amide-based polar solvent and stirred at 30 to 100°C for washing, washed several times with ion-exchanged water at 30 to 80°C, washed several times with a metal salt aqueous solution such as calcium acetate, and then dried to obtain a granular polyphenylene sulfide polymer (PPS granules). The granular polymer is fed into a vented extruder and melt-extruded into strands, which are then cooled with water at a temperature of 25° C. and then cut into chips to form PPS pellets.

[0057] A masterbatch is prepared by mixing the PPS granules obtained above as the polyarylene sulfide resin with inorganic particles and / or other thermoplastic resins in any desired ratio. The concentration of the inorganic particles and / or other thermoplastic resins in the masterbatch is preferably 1% to 25% by mass, more preferably 5% to 15% by mass. A concentration greater than 25% by mass may result in poor dispersibility and a larger dispersion diameter. A concentration less than 1% by mass may result in increased amounts of the masterbatch used upon dilution, which may be undesirable from a cost perspective. In the present invention, a preferred method for preparing the masterbatch is to use a device that applies shear stress, such as a twin-screw extruder. In this case, the masterbatch is preferably kneaded in the kneading section to achieve a resin temperature range of (PAS resin melting point + 5°C) or higher (PAS resin melting point + 80°C), more preferably (PAS resin melting point + 10°C) or higher (PAS resin melting point + 80°C), and even more preferably (PAS resin melting point + 15°C) or higher (PAS resin melting point + 70°C). The screw rotation speed is preferably in the range of 100 rpm to 1500 rpm. By setting the resin temperature and the screw rotation speed within the preferred ranges, the dispersion diameter of the dispersed phase can be controlled.

[0058] In the present invention, the value on the vertical axis of the differential molecular weight distribution curve (dw / dLogM) when the logarithm LogM of the molecular weight M is 4.0, 5.2, and 5.5 can be controlled by controlling the value on the vertical axis of the differential molecular weight distribution curve (dw / dLogM) during polymerization, by blending multiple types of PPS pellets with different molecular weights and feeding the blend into an extruder to control the value on the vertical axis of the differential molecular weight distribution curve (dw / dLogM), or by a combination of these methods. From the viewpoint of controlling the extrusion viscosity during film formation, a preferred example is blending multiple different types of PPS pellets.

[0059] In the present invention, first, PPS chips, optionally dried under reduced pressure at 180°C for 3 hours, and a masterbatch are mixed in a predetermined ratio, and the mixture is fed into a full-flight single-screw extruder with a melting zone set at 300 to 350°C, passed through a filter, and then extruded from a T-die type nozzle. The nozzle temperature is preferably 300 to 350°C, more preferably 305 to 325°C, and most preferably 305 to 315°C. Preferably, the mixture is rapidly cooled and solidified by being brought into close contact with a cooling drum having a surface temperature of 20 to 70°C while applying a static charge, to obtain an unstretched film in a substantially unoriented state.

[0060] Next, the unstretched film obtained above is biaxially stretched using a sequential biaxial stretching machine or a simultaneous biaxial stretching machine in a temperature range equal to or higher than the glass transition point (Tg) of the polyarylene sulfide resin, followed by one-stage or multi-stage heat setting at a temperature in the range of 150 to 280°C to obtain a biaxially oriented film. As the stretching method, a sequential biaxial stretching method (a stretching method combining stretching in one direction at a time, such as a method in which stretching in the longitudinal direction is performed followed by stretching in the width direction), a simultaneous biaxial stretching method (a method in which stretching in the longitudinal direction and then the width direction is performed simultaneously), or a combination thereof can be used. Here, a sequential biaxial stretching method in which stretching in the longitudinal direction is performed first and then in the width direction is illustrated as an example.

[0061] The unstretched film is heated by a group of heating rolls and stretched in the longitudinal direction (MD) to a magnification of 3.4 times or more, more preferably 3.6 times or more, and even more preferably 3.8 times or more in one or two or more stages (MD stretching). By maintaining the MD stretching within the above range and aligning the molecular chains in the longitudinal direction, stress propagation points are effectively formed during width direction stretching, thereby enabling control of the width direction thickness in this invention. There is no particular upper limit to the MD stretching ratio, but a preferred range is 5.0 times or less, more preferably 4.8 times or less, and even more preferably 4.5 times or less. If this range is exceeded, excessive orientation in one direction during MD stretching may result in deterioration of film formability due to film breakage during transverse stretching, or large variations in the width direction orientation angle during heat setting. The stretching temperature is Tg to Tcc (heat-up crystallization peak temperature), preferably in the range of (Tg + 5°C) to (Tcc - 5°C). The film is then cooled using a group of cooling rolls at 20 to 50°C. Stretching in the width direction (TD direction) following stretching in the MD direction is generally performed using, for example, a tenter. The film is gripped at both ends with clips and introduced into the tenter for width direction stretching (TD stretching). The stretching temperature is preferably (Tg (glass transition temperature of polyarylene sulfide) + 5°C) to (Tg + 40°C), more preferably (Tg + 7°C) to (Tg + 30°C). In the case of PPS, the temperature is 95°C to 135°C, more preferably 97°C to 125°C. The width direction stretching ratio is preferably 3.0 times or more and 4.5 times or less, from the viewpoint of obtaining a film with good flatness. The lower limit of the width direction stretching ratio is more preferably 3.1 times or more, even more preferably 3.2 times or more. The upper limit of the width direction stretching ratio is more preferably 4.2 times or less, even more preferably 4.0 times or less.

[0062] Next, the film is stretched again in the TD direction (TD stretching 2). The stretching temperature for TD stretching 2 is 200°C to melting point (Tm) - 30°C, preferably 215°C to Tm - 40°C. The stretching ratio for TD stretching 2 is preferably 1.01 to 2.00, more preferably 1.05 to 1.50. By performing TD stretching 2 at the above-mentioned stretching temperature and stretching ratio, the film is stretched in the width direction at a high temperature, which makes it possible to uniformize the orientation variation in the width direction.

[0063] Next, the stretched film is heat-set under tension (heat setting). The heat setting temperature can be the same throughout the heat setting zone, or it can be a single-stage heat setting or a multi-stage heat setting in which different temperatures are used in the first and second halves of the heat setting zone. The heat setting temperature is preferably 200°C or higher (melting point -20°C), more preferably 210°C or higher and 250°C or lower, and even more preferably 215°C or higher and 240°C or lower, from the viewpoint of minimizing variation in the orientation angle in the film width direction while maintaining the thermal stability required for processing. If the heat setting temperature is lower than 200°C, wrinkles may occur due to deformation during processing as an electrolyte membrane reinforcing member. If the heat setting temperature exceeds the melting point -20°C, the orientation angle may vary significantly, potentially resulting in poor flatness during processing.

[0064] Next, it is preferable to perform a relaxation treatment in the longitudinal direction and / or width direction while holding the heat-set biaxially oriented film with clips. In the present invention, it is preferable to perform the width direction relaxation treatment in two or more stages at different temperatures. Performing the relaxation treatment in two or more stages at different temperatures makes it possible to suppress rapid strain relaxation and effectively control thickness variation and orientation angle unevenness in the TD direction, making this a preferred embodiment. The relaxation rate is the ratio of the difference between the width between the clips before treatment and the width after treatment. For example, a relaxation rate of 2% indicates that if the width before treatment is 100 mm, then 2 mm (2%) is relaxed, resulting in a width of 98 mm after treatment. The relaxation rate of the previous stage (hereinafter sometimes abbreviated as Rx1) is preferably 1.0 to 10.0%, more preferably 3.0 to 7.0%. Furthermore, the temperature during the relaxation treatment (Rx1) is preferably (heat setting temperature -20°C) or higher (heat setting temperature +10°C) or lower. In the second relaxation treatment (hereinafter sometimes abbreviated as Rx2), the relaxation rate is preferably 0.1 to 5%, more preferably 1 to 4%. The temperature during the second relaxation treatment (Rx2) is preferably (heat setting temperature - 80°C) or higher (heat setting temperature - 10°C) or lower.

[0065] The film is then cooled, preferably to a temperature of 35°C or less, more preferably 25°C or less, and the film edges are removed and wound onto a core. Furthermore, from the viewpoint of improving thermal dimensional stability, the wound PPS film may be conveyed under tension under certain temperature conditions and subjected to an annealing treatment. The annealing temperature is preferably 130°C or higher and 190°C or lower. At temperatures above 190°C, excessive shrinkage strain is removed during the annealing treatment, resulting in a state in which the molecular chains are largely relaxed. When temperature and tension are applied to the film again in subsequent processes, this may lead to dimensional changes during processing, resulting in poor dimensional control during processing. At temperatures below 130°C, the removal of strain from the molecular structure by the annealing treatment may be incomplete, resulting in poor dimensional control during processing. The annealing temperature is more preferably 140°C or higher and 180°C or lower. The conveying tension during annealing is preferably 0.5 MPa to 3.0 MPa, more preferably 0.8 MPa to 2.0 MPa. The annealing time is preferably 1 to 200 seconds, more preferably 10 to 100 seconds, and even more preferably 10 to 50 seconds. The biaxially oriented polyarylene sulfide film of the present invention can be obtained by carrying out the annealing treatment while transporting the film at a speed of 1 to 100 m / min.

[0066] In the present invention, the polyarylene sulfide film or its film roll may be subjected to any processing such as molding, surface treatment, lamination, coating, printing, embossing, and etching, as necessary. The biaxially oriented polyarylene sulfide film of the present invention has excellent durability and can be suitably used for automobiles, various parts of electric and electronic materials, circuit substrates, heat-resistant tape substrates, films for toner stirrers for printing, and release films. In particular, it can be suitably used as an electrolyte membrane reinforcing member for fuel cells and water electrolysis devices, which require durability and dimensional stability, and as a current collector foil substrate for film capacitors.

[0067] In a preferred embodiment of the present invention, an electrolyte membrane reinforcing member having a biaxially oriented polyarylene sulfide film satisfies the following (a) and (b): (a) the amount of calcium ions in the polyarylene sulfide film is 10 mass ppm or less, and (b) in a differential molecular weight distribution curve measured by gel permeation chromatography of the polyarylene sulfide film layer, the value on the vertical axis of the differential molecular weight distribution curve (dw / dLogM) when the logarithm LogM of the molecular weight M on the horizontal axis is 5.2 is 0.15 or more and 0.60 or less.

[0068] By adopting this embodiment, it is possible to provide an electrolyte membrane reinforcing member that can control uneven orientation and thickness variations and has excellent processability.

[0069] In the present invention, an electrolyte membrane reinforcing member having a polyarylene sulfide film is a polyarylene sulfide film and / or laminate having an opening punched into a frame or picture frame shape corresponding to the outer peripheral shape of the solid electrolyte membrane, for example, as shown in Figure 1. The electrolyte membrane reinforcing member may be a laminate including at least one polyarylene sulfide film layer and an adhesive layer for adhesion to the electrolyte membrane. Examples of the laminate configuration include a polyarylene sulfide film layer only, a two-layer configuration of polyarylene sulfide film layer / adhesive layer, a polyarylene sulfide film layer / adhesive layer / polyarylene sulfide film layer, or a three-layer configuration of adhesive layer / polyarylene sulfide film layer / adhesive layer.

[0070] When the polyarylene sulfide film layer of the electrolyte membrane reinforcing member having the polyarylene sulfide film of the present invention is extracted with boiling nitric acid, the calcium ion content in the film is preferably 10 ppm by mass or less. If the calcium ion content exceeds 10 ppm by mass, when the film is used as a reinforcing member for a fuel cell or water electrolysis device, calcium element may leach out under the high temperature, high humidity, and strong acidity conditions within the fuel cell, causing contamination of the fuel cell catalyst and gas diffusion layer, and reducing the power generation capacity of the fuel cell. The calcium ion content is more preferably 5 ppm by mass or less, and even more preferably 3 ppm by mass or less. The calcium ion content can be controlled within the above range by using a polyarylene sulfide resin with low impurities, optimizing drying and extrusion conditions, and implementing a comprehensive design including lubricating particles to improve the quality of the film used. The calcium ion content is evaluated using the method described below.

[0071] The polyarylene sulfide film layer of the electrolyte membrane reinforcing member having the polyarylene sulfide film of the present invention preferably has a peak in the range of 4.0 to 6.0 in the differential molecular weight distribution curve measured by gel permeation chromatography (described below), and the value of the vertical axis of the differential molecular weight distribution curve when the logarithm Log M of the molecular weight M is 5.2 (dw / dLog M) is 0.15 to 0.60. Within this range, a large number of high-molecular-weight molecular chains are contained, molecular motion is suppressed, and when used as an electrolyte membrane reinforcing member, deformation due to temperature and pressure is small, and thickness and orientation unevenness can be reduced. If the value of the vertical axis of the differential molecular weight distribution curve when the logarithm Log M of the molecular weight M is 5.2 is less than 0.15, the film may be easily deformed by the temperature and pressure in the usage environment, resulting in large thickness variations. If the value on the vertical axis of the differential molecular weight distribution curve when the logarithm Log M of the molecular weight M is 5.2 is greater than 0.60, the viscosity during melt extrusion will be high due to the high molecular weight component content, which may result in large thickness fluctuations during molding into an electrolyte membrane reinforcing member and large thickness variations in the electrolyte membrane reinforcing member. From the above perspective, it is more preferable that the value on the vertical axis of the differential molecular weight distribution curve when the logarithm Log M of the molecular weight M is 5.2 is 0.20 or more. It is more preferable that the value on the vertical axis of the differential molecular weight distribution curve when the logarithm Log M of the molecular weight M is 5.2 is 0.55 or less.

[0072] In the polyarylene sulfide film layer of the electrolyte membrane reinforcing member having the polyarylene sulfide film of the present invention, the value of the vertical axis of the differential molecular weight distribution curve (dw / dLogM) when the logarithm LogM of the molecular weight M is 4.0, measured by gel permeation chromatography (described later), is preferably 0.10 or more and 0.40 or less. The value of the vertical axis of the differential molecular weight distribution curve indicates the content of low molecular weight components, and when this value is within the above range, it is possible to reduce the low molecular weight components while reducing thickness fluctuations and eluted components in the usage environment when used as an electrolyte membrane reinforcing member. If it is less than 0.10, the low molecular weight components will be too small, which may cause plastic deformation at the temperature and pressure in the usage environment and worsen thickness variation. If the value of the vertical axis of the differential molecular weight distribution curve when the logarithm LogM of the molecular weight M is 4.0 is greater than 0.40, the amount of low molecular weight components will be too large, which may result in poor durability at the temperature and pressure in the usage environment. From the above viewpoints, the value on the vertical axis of the differential molecular weight distribution curve when the logarithm Log M of the molecular weight M is 4.0 is more preferably 0.15 or more, and even more preferably 0.20 or more. The value on the vertical axis of the differential molecular weight distribution curve when the logarithm Log M of the molecular weight M is 4.0 is more preferably 0.35 or less, and even more preferably 0.30 or less.

[0073] In the polyarylene sulfide film layer of the electrolyte membrane reinforcing member having the polyarylene sulfide film of the present invention, in a differential molecular weight distribution curve measured by gel permeation chromatography described below, the value of the vertical axis of the differential molecular weight distribution curve when the logarithm Log M of the molecular weight M is 5.5 (dw / dLog M) is preferably 0.01 or more and 0.25 or less. Within this range, a large number of molecular chains with high molecular weight are contained, molecular motion is suppressed, and when used as an electrolyte membrane reinforcing member, deformation due to temperature and pressure is small, and thickness variation and orientation unevenness can be reduced. If the value of the vertical axis of the differential molecular weight distribution curve when the logarithm Log M of the molecular weight M is 5.5 is less than 0.01, there is a risk of deformation due to temperature and pressure in the usage environment, gradually increasing thickness variation. If the value on the vertical axis of the differential molecular weight distribution curve when the logarithm Log M of the molecular weight M is 5.5 is greater than 0.25, the content of high molecular weight components will be high, the viscosity during melt extrusion will be high, and thickness fluctuations during molding into an electrolyte membrane reinforcing member will be large, which may result in greater thickness variation of the electrolyte membrane reinforcing member. From the above perspective, the value on the vertical axis of the differential molecular weight distribution curve when the logarithm Log M of the molecular weight M is 5.5 is more preferably 0.02 or more, and even more preferably 0.05 or more. The value on the vertical axis of the differential molecular weight distribution curve when the logarithm Log M of the molecular weight M is 5.5 is more preferably 0.22 or less.

[0074] A preferred embodiment of the present invention is an electrolyte membrane reinforcing member in the form of a rectangular frame having an opening, wherein at least one film layer constituting the electrolyte membrane reinforcing member satisfies the following (A) and (B): (A) When the orientation angle is measured using the measurement method described later, the orientation angle is greater than -35° and less than 35°, greater than -90° and less than -55°, or greater than 55° and less than 90°; and (B) When the orientation angle is measured using the measurement method described later, the difference between the maximum and minimum values ​​of the orientation angle is greater than or equal to 0.5° and less than 20°.

[0075] The method for measuring the orientation angle will be described later.

[0076] By adopting this embodiment, it is possible to provide an electrolyte membrane reinforcing member with little orientation unevenness and excellent processability.

[0077] In the present invention, the electrolyte membrane reinforcing member refers to a film and / or laminate having an opening punched into a frame or picture frame shape corresponding to the outer peripheral shape of the solid electrolyte membrane, for example, as shown in Figure 1. The electrolyte membrane reinforcing member may be a laminate including at least one film layer and an adhesive layer for bonding to the electrolyte membrane. Examples of the laminate configuration include a film layer only, two-layer configuration of film layer / adhesive layer, film layer / adhesive layer / film layer, and three-layer configuration of adhesive layer / film layer / adhesive layer.

[0078] In view of chemical resistance and moist heat resistance, the film layer of the electrolyte membrane reinforcing member of the present invention preferably contains a polyester resin or a polyarylene sulfide resin as a main component. The film layer of the electrolyte membrane reinforcing member of the present invention is more preferably made of a polyarylene sulfide film containing a polyarylene sulfide resin as a main component. The film layer of the electrolyte membrane reinforcing member of the present invention is most preferably made of a polyphenylene sulfide film containing a polyphenylene sulfide resin as a main component, as it has mechanical strength, hydrolysis resistance, etc.

[0079] The rectangular frame-shaped electrolyte membrane reinforcing member of the present invention preferably has at least one side of 150 mm or more. By setting the length within this range, the area of ​​the electrolyte membrane can be increased, and the operating efficiency can be improved when the electrolyte membrane is used in a fuel cell or a water electrolysis device.

[0080] In order to ensure proper bonding to the electrolyte membrane and separator, the opening of the electrolyte membrane reinforcing member in the present invention preferably has an area of ​​30% or more and 90% or less of the outer peripheral shape of the fuel cell stack.

[0081] In the present invention, when at least one film layer of the electrolyte membrane reinforcing member is measured by cutting the upper four sides of the film layer frame along the outer periphery into 30 mm x 30 mm pieces, with one of the outer periphery directions of the electrolyte membrane reinforcing member being the 0° direction of the measuring instrument, it is preferable that the orientation angle is greater than -35° and less than 35°, greater than -90° and less than -55°, or greater than 55° and less than 90°. When the orientation angle is within the above range, misalignment of the orientation is reduced, resulting in less warping and deformation during bonding with other materials, improving stackability as an electrolyte membrane reinforcing member. When the orientation angle is greater than -55° and less than -35°, or greater than 35° and less than 55°, misalignment of the orientation axis is large, which may result in warping and deformation during bonding with other materials. The orientation angle is preferably greater than -30° and less than 30°, or greater than -90° and less than -60°, or greater than 60° and less than 90°, more preferably greater than -25° and less than 25°, or greater than -90° and less than -65°, or greater than 65° and less than 90°, even more preferably greater than -20° and less than 20°, or greater than -90° and less than -70°, or greater than 70° and less than 90°, and most preferably greater than -20° and less than 20°.

[0082] In at least one film layer of the electrolyte membrane reinforcing member of the present invention, the difference between the maximum and minimum orientation angles is preferably 0.5° or more and 20° or less. When the difference between the maximum and minimum orientation angles is within the above range, the orientation unevenness is small, warping during the heat processing for lamination can be reduced, and stack processing can be facilitated. When the difference between the maximum and minimum orientation angles is less than 0.5°, the difference between the maximum and minimum orientation angles needs to be extremely small, and the molecular chains may be too uniformly aligned, which may make the electrolyte membrane reinforcing member more likely to tear. When the difference between the maximum and minimum orientation angles exceeds 20.0°, warping during lamination processing may become significant, resulting in a decrease in flatness. The difference between the maximum and minimum orientation angles is more preferably 3.0° or more, and even more preferably 5.0° or more. The difference is more preferably 18.0° or less, and even more preferably 16.0° or less.

[0083] In the present invention, at least one film layer of the electrolyte membrane reinforcing member preferably exhibits a thickness variation of 0.5% or more and 10.0% or less when measured at 10 mm intervals around the outer periphery of the frame-shaped portion of the film layer. In the present invention, the thickness measurement is performed at a position 5 mm inward from the outer periphery of the rectangular frame-shaped electrolyte membrane reinforcing member. Within the above range, thickness variation is small when stacked, facilitating stack processing. The thickness variation of at least one film layer of the electrolyte membrane reinforcing member is more preferably 1.0% or more. The thickness variation of at least one film layer of the electrolyte membrane reinforcing member is more preferably 8.0% or less, and even more preferably 6.0% or less. When a film with little thickness variation and orientation variation, as described below, is used as the film layer of the electrolyte membrane reinforcing member, the thickness variation of the electrolyte membrane reinforcing member tends to be low.

[0084] In at least one film layer of the electrolyte membrane reinforcing member of the present invention, the tan δ peak temperature determined by dynamic viscoelasticity measurement is preferably 120°C or higher and 160°C or lower. When the tan δ peak temperature determined by dynamic viscoelasticity measurement is within the above range, heat resistance in the usage environment can be ensured, enabling long-term use. The tan δ peak temperature is more preferably 125°C or higher. The tan δ peak temperature is more preferably 150°C or lower, and even more preferably 145°C or lower.

[0085] In the present invention, the electrolyte membrane reinforcing member can be joined to the electrolyte membrane or the separator via an adhesive layer that constitutes the electrolyte membrane reinforcing member, and known methods (for example, the methods described in JP-A-2015-2029 and JP-A-2022-69952) can be applied.

[0086] The cells used in fuel cells and water electrolysis devices have a structure in which an electrolyte membrane reinforcing member having the biaxially oriented polyarylene sulfide film of the present invention as a film layer serves as the outer frame of the electrolyte membrane, and a catalyst layer, an electrode substrate, and a separator are sequentially laminated on both sides of the electrolyte membrane. Of these, an electrolyte membrane having a catalyst layer laminated on both sides (i.e., a layer structure of catalyst layer / electrolyte membrane / catalyst layer) is called a catalyst-coated electrolyte membrane (CCM), and an electrolyte membrane having a catalyst layer and a gas diffusion substrate sequentially laminated on both sides of the electrolyte membrane (i.e., a layer structure of gas diffusion substrate / catalyst layer / electrolyte membrane / catalyst layer / gas diffusion substrate) is called a membrane electrode assembly (MEA).

[0087] Common methods for manufacturing a CCM include a coating method in which a catalyst layer paste composition for forming a catalyst layer is applied to the surface of an electrolyte membrane and dried, and a method in which only the catalyst layer is prepared on a substrate and then this catalyst layer is transferred to laminate the catalyst layer on the electrolyte membrane (transfer method).The CCM and electrolyte membrane reinforcing member are attached by heat pressing, overlapping the edge of the electrolyte membrane in this CCM or MEA and the periphery of the opening of the film of the present application, which has been cut out into a frame shape and provided with an adhesive layer.

[0088] When an MEA is fabricated by pressing, known methods (e.g., the chemical plating method described in Electrochemistry, 1985, 53, p. 269; the hot press bonding method for gas diffusion electrodes described in Electrochemical Science and Technology, edited by the Electrochemical Society (J. Electrochem. Soc.), 1988, 135, 9, p. 2209; etc.) can be applied. The temperature, tension, and pressure during pressing can be appropriately selected depending on the thickness and moisture content of the electrolyte membrane, the catalyst layer, and the electrode substrate. Specific pressing methods include roll pressing with specified pressure and clearance (e.g., JP 2007-180031 A) and plate pressing with specified pressure. From the viewpoints of industrial productivity and suppression of thermal decomposition of polymer materials having ionic groups, pressing is preferably performed in the range of room temperature to 200°C.

[0089] The fuel cell and water electrolysis device of the present invention will be described below. The fuel cell of the present invention has an MEA using the biaxially oriented polyarylene sulfide film of the present invention. Using the biaxially oriented polyarylene sulfide film of the present invention in the fuel cell provides excellent processability, leading to reduced stack assembly yield.

[0090] The water electrolysis device of the present invention has an MEA using the biaxially oriented polyarylene sulfide film of the present invention. By using the biaxially oriented polyarylene sulfide film of the present invention in the water electrolysis device, excellent processability is achieved, which leads to a reduction in the yield of stack assembly.

[0091] Next, a metallized film made using the biaxially oriented polyarylene sulfide film of the present invention, a current collecting foil and a film capacitor made using the same, and methods for producing them will be described.

[0092] The biaxially oriented polyarylene sulfide film of the present invention is preferably made into a metallized film by providing a metal layer on at least one surface. In addition to circuit substrates, the biaxially oriented polyarylene sulfide film of the present invention can be used as a current collector foil or a capacitor because it exhibits excellent alignment irregularities and thickness variations even when thinned. To make a metallized film, a metal layer is provided on at least one surface, and the metal may be one or more of copper, copper alloy, aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy. For lithium-ion batteries, the metal layer is preferably aluminum for the positive electrode current collector foil, and copper for the negative electrode current collector foil. For sodium-ion batteries, the positive electrode current collector foil may be aluminum and the negative electrode current collector foil may be copper, or both the positive and negative electrode current collector foils may be aluminum. Preferred methods for forming the metal layer include vacuum deposition, sputtering, electrolytic plating, and electroless plating, and these methods may also be combined.

[0093] The metallized film of the present invention can be used as an electrode plate by forming an electrode material layer on at least one surface. Examples of electrode materials include lithium-containing metal oxides such as lithium cobalt oxide, lithium manganese oxide, and lithium nickel oxide, and lithium-containing metal phosphates such as lithium iron phosphate and lithium iron manganese phosphate for the positive electrode of lithium-ion batteries. Examples of active materials include sodium-containing metal oxides, sodium-containing metal phosphates, and sodium-containing Prussian blue analogs for the positive electrode of sodium-ion batteries. Acetylene black, ketjen black, carbon nanotubes, and graphene may also be used as conductive materials, and polyvinylidene fluoride may be used as binders. Examples of active materials that can be used for negative electrodes include graphite, carbon black, acetylene black, hard carbon, soft carbon, carbon nanotubes, and graphene; lithium alloy materials such as tin and silicon; lithium titanate; and metallic lithium, with binders such as carboxymethyl cellulose, styrene-butadiene copolymer, and polyvinylidene fluoride.

[0094] To fabricate electrodes, an active material and a conductive additive are first dispersed in a binder resin solution to prepare an electrode coating solution. This coating solution is then applied to a metal foil or metallized film, and the solvent is dried to obtain a positive electrode and a negative electrode, respectively. The thickness of the coating film after drying is preferably 30 μm to 500 μm. Furthermore, it is preferable to apply pressure to the active material layer formed on the metallized film using a rolling method such as a roll press method to densify the active material layer. The active material layer may also be further densified by heating the roll during rolling. Because the metallized film of the present invention has excellent dimensional stability at high temperatures, it is possible to fabricate electrodes with excellent flatness even when the solvent is dried at high temperatures, thereby improving productivity.

[0095] A laminate having a plurality of electrode groups each having a lithium secondary battery separator between the obtained positive and negative electrodes so as to be in contact with the active material layer of each electrode, or a wound body having a positive electrode, a separator, and a negative electrode stacked and wound up, can be enclosed in an exterior material such as a metal can or an aluminum laminate film to form a secondary battery. The metallized film using the biaxially oriented polyarylene sulfide film of the present invention has excellent processability, and when multiple films are stacked together as a current collector foil during winding, it exhibits excellent processability with little thickness variation, and it is possible to produce a stable wound body with little shear even when wound at high speed and high tension.

[0096] For example, the film capacitor of the present invention can be obtained by laminating or winding the above-described metallized film of the present invention by various methods. A preferred example of a method for producing a wound film capacitor is as follows.

[0097] Aluminum is vapor-deposited under reduced pressure on one side of a biaxially oriented polyarylene sulfide film. This vapor deposition is performed in stripes with longitudinal margins. Next, a blade is used to slit the center of each vapor-deposited area and the center of each margin on the surface, producing a tape-like take-up reel with a margin on one side of the surface. Two tape-like take-up reels with left and right margins are stacked and wound together so that the vapor-deposited area extends beyond the margin in the width direction, producing a wound body.

[0098] When vapor deposition is performed on both sides, one side is vapor-deposited in stripes with a longitudinal margin, and the other side is vapor-deposited in stripes so that the longitudinal margin is located in the center of the vapor-deposited area on the back side. Next, a blade is cut into the center of the margins on both sides to create a tape-like take-up reel with a margin on one side on each side (for example, if there is a margin on the right side of the front side, there is a margin on the left side of the back side). The resulting reel and one unvapor-deposited laminated film are stacked and wound together so that the metallized film extends beyond the laminated film in the width direction, resulting in a wound body. The metallized film using the biaxially oriented polyarylene sulfide film of the present invention has excellent processability, exhibiting minimal thickness variation when stacked together to form a current collector foil, and exhibiting excellent processability with minimal shear even when wound at high speed and high tension, enabling the production of a stable wound body.

[0099] A method for obtaining the film capacitor of the present invention from the metallized film of the present invention includes, for example, removing the core material from the wound body prepared as described above, pressing the wound body, spraying metallikon on both end faces to form external electrodes, and welding lead wires to the metallikon to form a wound film capacitor. Film capacitors have a wide range of applications, including power control units for electric vehicles (e.g., electric vehicles, hybrid vehicles, and fuel cell vehicles) and electric aircraft (e.g., drones), railroad vehicles, solar and wind power generation, and general home appliances. The film capacitor of the present invention can also be suitably used for these applications. The polypropylene film of the present invention can also be used for various applications, such as packaging films, release films, processing films, sanitary products, agricultural products, construction products, and medical products, and is particularly suitable for applications involving a heating process in film processing.

[0100] The biaxially oriented polyarylene sulfide film of the present invention can be produced by the above-mentioned process, and the resulting film has little orientation unevenness and thickness variation. Taking advantage of these characteristics, the film of the present invention can be suitably used as electrical insulating paper for motors, in laminates with fiber sheets, etc., or in applications where it is important to suppress warping due to orientation unevenness during lamination processing and wrinkles due to thickness variation. When electrical insulating paper for motors using the biaxially oriented polyarylene sulfide film of the present invention is used in motors, it has superior processability compared to conventional electrical insulating paper, which leads to reduced yield during slot insertion.

[0101] [Method for measuring properties] (1) Content of polyarylene sulfide resin The infrared absorption spectrum of the biaxially oriented polyarylene sulfide film of the present invention is measured by the ATR method using an infrared spectrophotometer (PerkinElmer, Spectrum 100 / Universal ATR (single reflection, crystal used: diamond / ZnSe)). From the obtained infrared absorption spectrum, the content of polyarylene sulfide resin is determined from the ratio of the peak due to the φ-S stretching vibration group based on the sulfide bond of polyarylene sulfide to the peak due to other substances. In order to convert the peak height ratio to a mass ratio, a calibration curve was created in advance using samples with known mass ratios (for example, olefins used as incompatible resins), and the content of polyarylene sulfide resin was calculated from the ratio to the total amount of polyarylene sulfide and other substances.

[0102] (2) Collection of Evaluation Rolls The intermediate product rolls obtained from each Example and Comparative Example were rewound and slit at intervals of ±200 mm in the width direction, with the center of the intermediate product roll designated as 0 mm, and at intervals of ±400 mm from the cross section to both ends to obtain a total of five film rolls. The resulting film rolls were designated as product rolls starting from one end (left side) of the intermediate product roll to the other end (right side), namely, the first (left side), second, third (center), fourth, and fifth (right side). The first, third, and fifth product rolls were designated as the measurement targets. For convenience, the first product roll was designated "-1," the third "-2," and the fifth "-3." That is, in Example 1, the first product roll (left end) was designated Example 1-1, the third product roll (center) was designated Example 1-2, the fifth product roll (right end) was designated Example 1-3, and so on. Similar designations are used for the other Examples and Comparative Examples.

[0103] In the present invention, if at least one of "-1", "-2", and "-3" satisfies the range, it is considered to be acceptable.

[0104] (3-1) Thickness variation (%) in the film width direction Using an electronic micrometer K-306C (manufactured by Anritsu Meter Co., Ltd.), a film sample was cut out from the center of a 400 mm wide film roll of the biaxially oriented polyarylene sulfide film of the present invention so as to have a dimension of 300 mm in the width direction and 50 mm in the longitudinal direction. The thickness in the film width direction was continuously measured, and the thickness variation was calculated from the maximum thickness, minimum thickness, and average thickness as follows: Width direction thickness variation (%) = (maximum thickness - minimum thickness) / average thickness x 100

[0105] (3-2) Thickness variation (%) in the film longitudinal direction Using an electronic micrometer K-306C (manufactured by Anritsu Meter Co., Ltd.), a film sample was cut out from the center of a 400 mm wide film roll of the biaxially oriented polyarylene sulfide film of the present invention so as to have a width direction of 50 mm and a length direction of 300 mm. The thickness in the film longitudinal direction was continuously measured, and the thickness was calculated from the maximum thickness, minimum thickness, and average thickness as follows: Width direction thickness variation (%) = (maximum thickness - minimum thickness) / average thickness x 100

[0106] (4) Thickness Variation (%) of Film Layer Used in Electrolyte Membrane Reinforcement Member The film layer removed from the electrolyte membrane reinforcing member was measured using a contact-type electronic micrometer (K-312A model) manufactured by Anritsu Corporation in an atmosphere of 23°C and 65% RH. Measurements were taken along the frame at 10 mm intervals at positions 5 mm inward from the outer periphery of the rectangular frame-shaped electrolyte membrane reinforcing member, and the thickness was calculated from the maximum and minimum thicknesses as follows: Thickness Variation (%) of Film Layer Used in Electrolyte Membrane Reinforcement Member = (Maximum Thickness - Minimum Thickness) / Average Thickness x 100

[0107] (5) Orientation angle from the film longitudinal direction, difference between maximum and minimum orientation angles The biaxially oriented polyarylene sulfide film of the present invention was evaluated using a microwave transmission molecular orientation meter MOA-6015 (manufactured by Oji Scientific Instruments Co., Ltd.) at a frequency of 15 GHz. The center of a 400 mm wide film roll was cut into a piece 300 mm in the film width direction x 30 mm in the longitudinal direction, and the cut film sample was further cut every 30 mm in the width direction to obtain a total of 10 film samples measuring 30 mm in the film width direction x 30 mm in the longitudinal direction. The orientation angle was determined with the film longitudinal direction as the 0° direction of the measuring instrument (the measured orientation angle range was -90° to 90°). The average value of the orientation angles at 10 measurement points in the width direction was taken as the orientation angle from the film longitudinal direction, and the difference between the maximum and minimum values ​​of the orientation angles at 10 measurement points in the width direction was calculated using the following formula: (i) When the orientation angle measured at 10 points in the width direction is greater than -35° and less than 35°, the difference between the maximum and minimum orientation angles is used as the representative value. (ii) When the orientation angle measured at 10 points in the width direction is greater than -90° and less than -55°, the difference between the maximum and minimum orientation angles is used as the representative value. (iii) When the orientation angle measured at 10 points in the width direction is greater than 55° and less than 90°, the difference between the maximum and minimum orientation angles is used as the representative value. (iv) When the orientation angle measured at 10 points in the width direction includes both the ranges of greater than -90° and less than -55°, and greater than 55° and less than 90°, the representative value is 180° - (the difference between the maximum and minimum orientation angles).

[0108] (6) Orientation Angle of the Film Layer Used in the Electrolyte Membrane Reinforcement Member, and Difference Between the Maximum and Minimum Orientation Angle The film layer removed from the electrolyte membrane reinforcing member was evaluated using a microwave transmission molecular orientation analyzer MOA-6015 (manufactured by Oji Scientific Instruments Co., Ltd.) at a frequency of 15 GHz. One of the directions along the outer periphery of the rectangular frame-shaped electrolyte membrane reinforcing member was designated the 0° direction of the measurement instrument, and the frame-shaped portion of the film layer used in the electrolyte membrane reinforcing member was cut into pieces measuring 30 mm x 30 mm along the outer periphery, with the four sides of the frame being 30 mm x 30 mm. The orientation angle of the film layer removed from the electrolyte membrane reinforcing member was determined from the cut samples (the measured orientation angle range was -90° to 90°). The average value of the orientation angle of the frame-shaped portion of the film layer used in the obtained electrolyte membrane reinforcing member was defined as the orientation angle of the film layer, and the difference between the maximum and minimum orientation angles at the top of the frame was calculated using the following formula: (i) When all of the orientation angles measured in the width direction were greater than -35° and less than 35°, the difference between the maximum and minimum orientation angles was used as the representative value. (ii) When the orientation angles measured in the width direction are all between -90° and -55°, the difference between the maximum and minimum orientation angles is taken as the representative value. (iii) When the orientation angles measured in the width direction are all between 55° and 90°, the difference between the maximum and minimum orientation angles is taken as the representative value. (iv) When the orientation angles measured in the width direction include both the ranges of between -90° and -55°, and between 55° and 90°, the representative value is taken as 180° - (the difference between the maximum and minimum orientation angles).

[0109] (7) Elastic Modulus at 130°C The biaxially oriented polyarylene sulfide film of the present invention was subjected to a tensile test in accordance with JIS K7127 (1999) using a tensile tester (RTG-1210 manufactured by A&D Company, Limited) at a temperature of 130°C and a pulling rate of 300 mm / min, with a 10 mm wide sample film set so that the chuck length was 50 mm.

[0110] The elastic modulus was determined by calculating the load difference at a calculation interval of 0.2 mm within the measurement range of displacement from 0 mm to 10 mm, with the start point of the displacement being 0 mm and the end point being 10 mm. The second, third, and fourth coordinates from the maximum were used as the original data and linearized using the least squares method, and the slope was taken as the elastic modulus. The specimens were cut so that the direction of the specimen length was the longitudinal direction and the width direction, and five specimens were measured for each, and the average was calculated for each. Measuring device: RTG-1210 manufactured by A&D Company, Limited Sample size: specimen length 150 mm x width 10 mm Length between chucks: 50 mm Tensile speed: 300 mm / min Measurement environment: 130°C Analysis conditions: displacement mode Start point: 0 mm End point: 10 mm Pitch: 0.2 mm

[0111] (8) Center Surface Average Roughness SRa The center surface average roughness SRa of the biaxially oriented polyarylene sulfide film of the present invention was determined using a Surfcorder ET30HK manufactured by Kosaka Laboratory under the following conditions: Stylus curvature radius: 2 μm, Cutoff: 0.25 mm, Measurement length: 0.5 mm, Measurement interval: 5 μm, Number of measurements: 40

[0112] (9) Calcium Ion Amount The biaxially oriented polyarylene sulfide film of the present invention was cut with ceramic scissors to a weight of 4 g to prepare an analytical sample. After washing the surface with ultrapure water, the film was heated and extracted for 2 hours in 100 mL of a pre-boiled 5% by mass nitric acid solution. Qualitative analysis of this extracted solution was performed using ICP mass spectrometry (Inductively Coupled Plasma Mass Spectrometry: ICP-MS) to determine the amount of calcium ions extracted per unit mass of the sample. Apparatus: Agilent 8800 manufactured by Agilent Technologies

[0113] (10) Value of the Vertical Axis of the Differential Molecular Weight Distribution Curve (dw / dLogM) A differential molecular weight distribution curve was prepared for the biaxially oriented polyarylene sulfide film of the present invention in accordance with JIS K7252 (2016). Specifically, 5 mL of 1-chloronaphthalene (1-CN) was added to 5 mg of the film sample, and the mixture was gently stirred at 210 to 220°C for 20 minutes (visual confirmation of dissolution). Then, filtration was performed using a 0.5 μm filter. A GPC curve was obtained by measurement under the conditions shown below. The obtained GPC curve was converted using a molecular weight calibration curve prepared by approximating the logarithm of the molecular weight of polystyrene with a cubic equation of the elution time, and the weight fraction was calculated by normalizing the peak area to 1. Note that the molecular weight is a relative value based on polystyrene. A differential molecular weight distribution curve can be prepared by plotting the logarithm of the molecular weight M (LogM) on the horizontal axis and the weight fraction (dw / dLogM) on the vertical axis. From the obtained differential molecular weight distribution curve, the vertical axis value (dw / dLogM) was read when the horizontal axis value (LogM) was 4.0, 5.2, and 5.5. Apparatus: High-temperature GPC apparatus (instrument No. GPC-H-2, PL-GPC220 manufactured by Polymer Laboratories) Detector: Differential refractive index detector RI Data interval: every 0.5 seconds Column: Shodex UT-G (guard column) PLgel 10 m MIXED-B-LS (2 columns) (8.0 mm x 30 cm, manufactured by Polymer Laboratories) Solvent: 1-chloronaphthalene Flow rate: 0.7 mL / min Column temperature: 210°C Injection volume: 0.200 mL Standard sample: Monodisperse polystyrene manufactured by Tosoh

[0114] (11) Tan δ Peak in Dynamic Viscoelastic Measurement of Film Layer Used in Electrolyte Membrane Reinforcement Member The film layer removed from the electrolyte membrane reinforcing member was cut into strips with a length of 50 mm and a width of 5 mm, with the length parallel to the direction of the larger average value of the orientation angle of the electrolyte membrane reinforcing member, and both ends were attached to chucks with a chuck distance of 10 mm for measurement. The loss tangent tan δ = E" / E' was calculated from the storage modulus E' and loss modulus E" obtained at each temperature. The apex of the peak observed in the obtained tan δ curve was read and defined as the tan δ peak temperature. Apparatus: EXSTAR DMS6100 (Seiko Instruments Inc.) Measurement mode: Tension Measurement temperature range: 25°C to 280°C Heating rate: 3°C / min Measurement atmosphere: Air Frequency: 1 Hz Displacement: 10.0 μm

[0115] (12) Resonance Parameter (Q Value) The biaxially oriented polyarylene sulfide film of the present invention was evaluated at a frequency of 15 GHz using a microwave molecular orientation meter (MOA-6015, manufactured by Oji Scientific Instruments Co., Ltd.). The center of the film roll was cut into a size of 300 mm in the film width direction and 30 mm in the longitudinal direction, and the cut film sample was further cut every 30 mm in the width direction to obtain a total of 10 film samples each measuring 30 mm in the film width direction and 30 mm in the longitudinal direction. For each measurement, the measurement angle of the film was rotated from 0° to 150° in 30° increments, and the angle was changed to six points, and the resonance parameter (Q value) was measured at each angle, and the average value was calculated.

[0116] (13) Minute endothermic peak temperature (T-meta) The biaxially oriented polyarylene sulfide film of the present invention was measured in accordance with JIS K7121 (1999) using a differential scanning calorimeter, a Rigaku DSC (Thermo plus EVO2 DSCvesta-SL). 5 mg of the film sample was sealed in an aluminum pan and heated from 25°C to 350°C at a heating rate of 20°C / min. The peak temperature of the observed endothermic peak of melting was taken as the melting point (Tm), and the temperature of the minute endothermic peak appearing in the temperature range of 150°C to Tm°C was taken as T-meta. The melting point here was the point at which the difference from the baseline of the DSC chart was greatest. Since the minute endothermic peak was observed in the first run of DSC and not observed in the second run in which the temperature was once raised above Tm and the thermal history was erased, it can be confirmed by comparing both DSC charts. The measurement was carried out three times for each sample, and the average values ​​obtained were taken as the melting point and minute endothermic peak (T-meta) of that sample.

[0117] (14) Flatness A hot melt adhesive (Toagosei Co., Ltd.: "Aronmelt" PPET1303S) was applied to the biaxially oriented polyarylene sulfide film of the present invention using a bar coater and dried for 60 seconds in an oven heated to 100°C to obtain a biaxially oriented polyarylene sulfide / adhesive layer polyarylene sulfide film laminate with an adhesive layer thickness of 10 μm. The obtained polyarylene sulfide film laminate was cut into a size of 150 mm x 150 mm, stacked so that the adhesive layers were in contact with each other, and bonded using a press at 160°C, 2.0 MPa, and 30 seconds. The obtained pressure-bonded film was placed on a surface plate, and the curl state of the four corners was observed in this state. The average value of the warpage (mm) at the four corners was calculated and evaluated according to the following criteria. A: The warpage was less than 5 mm. B: The warpage was 5 mm or more but less than 10 mm. C: The warpage was 10 mm or more but less than 15 mm. D: The amount of warpage is 15 mm or more.

[0118] (15) Processability (I) One hundred biaxially oriented polyarylene sulfide films of the present invention were obtained by cutting 100 pieces of 150 mm x 150 mm size from the center of a film roll in the film width direction in the longitudinal direction between two steel plates (150 mm x 150 mm, thickness 250 μm), and then stacking 100 sheets of the film. Pressure-sensitive paper ("Prescale" (registered trademark) LW, manufactured by Fujifilm Corporation) was sandwiched between the 25th and 26th sheets, the 50th and 51st sheets, and the 75th and 76th sheets. Pressure was applied to a pressure of 4 MPa at room temperature for 10 minutes using a press with a uniform surface pressure, and then released. The color change of the pressure-sensitive paper was evaluated according to the following criteria. A: Uniform pressure was applied to all pressure-sensitive papers. B: Pressure distribution was observed in part of the pressure-sensitive paper. C: Pressure distribution was observed across multiple pressure-sensitive papers. D: Pressure distribution was large.

[0119] (16) Processability (II) The biaxially oriented polyarylene sulfide film of the present invention was wound around a 3-inch core to a winding length of 500 m, and subjected to aging treatment for 72 hours in an oven maintained at 80°C. A 300 mm wide x 250 mm long piece was cut out from the center of the roll sample in the width direction of the film, and the appearance was evaluated as follows: A: No wrinkles or warping occurred B: Slight wrinkles or warping occurred C: Small wrinkles or warping occurred D: Other (large wrinkles, unevenness, warping, etc.)

[0120] (17) Conveyability (I) The biaxially oriented polyarylene sulfide film of the present invention is slit to a width of 400 mm and continuously wound into a 1000 m slit roll. At this time, the number of defects caused by scratches on the roll surface is counted using a defect detector and evaluated as follows. A: The number of defects caused by scratches in the roll is 9 or less. B: The number of defects caused by scratches in the roll is 10 to 50. C: The number of defects caused by scratches in the roll is more than 50.

[0121] (18) Conveyance (II) The biaxially oriented polyarylene sulfide film of the present invention was unwound, and while being conveyed on a roll at a take-up speed of 40 m / min, it was conveyed for 15 seconds in a drying oven heated to 120°C and then wound up. A length of 1000 m was continuously carried out, and the above processing was carried out on five rolls, and the conveyance (II) was evaluated based on the winding appearance of the obtained rolls as follows. A: Of the five rolls, wrinkles occurred in one or less rolls. B: Of the five rolls, wrinkles occurred in two or more rolls.

[0122] (19) Conveyance (III) From the roll sample evaluated in Conveyance (II), a piece measuring 300 mm in width and 250 mm in length was cut out from the center of the film, and the state of wrinkles and unevenness was visually observed and rated as follows: A: No wrinkles or unevenness. B: Slight wrinkles, unevenness, or curling. C: Small wrinkles, unevenness, or curling. D: Other (large wrinkles, unevenness, or curling, etc.).

[0123] (20) Gas Leakage Property A hot melt adhesive ("Aronmelt" (registered trademark) PPET1303S, manufactured by Toagosei Co., Ltd.) was applied as an adhesive layer to the biaxially oriented polyarylene sulfide film of the present invention using a bar coater, and the film was dried for 60 seconds in an oven heated to 100°C to obtain a biaxially oriented polyarylene sulfide / polyarylene sulfide film laminate with an adhesive layer thickness of 10 μm.

[0124] Next, a 90 mm x 140 mm perfluorosulfonic acid resin (manufactured by DuPont: "Nafion" (registered trademark) 117) was used as the electrolyte membrane, and electrolyte membrane reinforcing members (outer periphery 150 mm x 200 mm, inner periphery 88 mm x 138 mm) punched out of the polyarylene sulfide film laminate in a frame shape were set on both sides of the electrolyte membrane, and the layers were stacked so that the adhesive layers were in contact with each other, and bonded under conditions of 115°C, 3 MPa, and 45 seconds to prepare an electrolyte membrane having an electrolyte membrane reinforcing member. Five electrolyte membranes having electrolyte membrane reinforcing members were stacked together to form an evaluation cell (electrode area 126 cm). ２ ) and used as a tightening evaluation cell so as to obtain a predetermined surface pressure.

[0125] The evaluation cell was subjected to 1,000 cycles using a thermal shock tester (TSE-11 thermal shock tester manufactured by Espec Corporation), with one cycle consisting of 30 minutes at -40°C and 30 minutes at 125°C. Nitrogen gas was sealed into the gas flow path of the JARI standard cell to a pressure of 300 kPa, and the cell was left to stand for 2 hours. The presence or absence of gas leakage was evaluated based on the change in pressure, and the durability of the cell was evaluated according to the following criteria: A: There was no change in the pressure of the sealed gas, and there was no problem in practical use. B: The pressure of the sealed gas decreased, causing a gas leak.

[0126] Reference Example 1: Preparation of Polyphenylene Sulfide Resin Granules (PPS Granules 1) A 1-kilometer SUS vessel equipped with a stirrer was charged with 1 kmole of 47% sodium hydrosulfide, 1.02 kmole of 47% sodium hydroxide, 1.6 kmole of N-methyl-2-pyrrolidone (NMP), 0.3 kmole of sodium acetate, and 100 kg of ion-exchanged water. While stirring at 240 rpm and passing nitrogen through at atmospheric pressure, the mixture was gradually heated to 235°C over approximately 180 minutes. After distilling 209 kg of water and 0.4 kg of NMP, the reactor was cooled to 160°C. The amount of hydrogen sulfide released was 0.02 kmole. To the remaining mixture, 1.02 kmole of p-dichlorobenzene (p-DCB) and 2.40 kmole of NMP were added. The reactor was then sealed under nitrogen gas. The temperature was raised from 160 ° C to 220 ° C over 100 minutes while stirring at 400 rpm, and the reaction was carried out at 220 ° C for 225 minutes. Next, the temperature was raised from 220 ° C to 255 ° C over 60 minutes, 0.8 kmol of water was poured into the system over 10 minutes, and the reaction was continued for 380 minutes. Thereafter, the mixture was cooled from 255 ° C to 200 ° C over 100 minutes. After reaching 150 ° C, the mixture was rapidly cooled to near room temperature using a blower. The contents were removed, 1 kiloliter of NMP was added, and the mixture was stirred at 85 ° C for 30 minutes, after which the solvent and solids were filtered off using an 80 mesh sieve. 1 kiloliter of NMP was added to the obtained solid, and the mixture was stirred at 85 ° C for 30 minutes and filtered off. This operation of adding 1 kiloliter of warm water to the obtained solid, stirring at 70 ° C for 30 minutes, and filtering was repeated three times. To the resulting solid, 4.5 kg of calcium acetate monohydrate and 1 kiloliter of warm water were added, and the mixture was stirred at 70°C for 30 minutes and filtered. The procedure of adding 1 kiloliter of warm water to the resulting solid, stirring at 70°C for 30 minutes, and filtering was repeated twice. The resulting solid was dried under reduced pressure at 120°C for 5 hours to obtain PPS granules 1 with a high molecular weight and a narrow molecular weight distribution.

[0127] Reference Example 2: Preparation of Polyphenylene Sulfide Resin Granules (PPS Granules 2) A 1-kilometer SUS vessel equipped with a stirrer was charged with 1 kmole of 47% sodium hydrosulfide, 1.02 kmole of 47% sodium hydroxide, 1.65 kmole of N-methyl-2-pyrrolidone (NMP), 0.3 kmole of sodium acetate, and 100 kg of ion-exchanged water. While stirring at 240 rpm and passing nitrogen through at atmospheric pressure, the mixture was gradually heated to 235°C over approximately 180 minutes. After distilling 209 kg of water and 0.4 kg of NMP, the reactor was cooled to 160°C. The amount of hydrogen sulfide released was 0.02 kmole. To the remaining mixture, 0.0004 kmole of 1,2,4-trichlorobenzene, 1.02 kmole of p-dichlorobenzene (p-DCB), and 1.35 kmole of NMP were added. The reactor was then sealed under nitrogen gas. The temperature was raised from 160°C to 270°C over 180 minutes while stirring at 400 rpm, and the reaction was carried out at 270°C for 135 minutes. The mixture was cooled from 270°C to 200°C over 100 minutes. Simultaneously with the start of cooling, 0.8 kmoles of water was poured into the system over 10 minutes. After reaching 200°C, the mixture was rapidly cooled to near room temperature using a blower. The contents were removed, 1 kiloliter of NMP was added, and the mixture was stirred at 85°C for 30 minutes, after which the solvent and solids were filtered through an 80 mesh sieve. 1 kiloliter of NMP was added to the obtained solid, and the mixture was stirred at 85°C for 30 minutes and filtered. 1 kiloliter of warm water was added to the obtained solid, and the mixture was stirred at 70°C for 30 minutes and filtered. This operation was repeated three times. 1 kiloliter of a 0.005 wt% aqueous calcium acetate solution was added to the obtained solid, and the mixture was stirred at 70°C for 30 minutes and filtered. The resulting solid was added with 1 kiloliter of warm water, stirred at 70°C for 30 minutes, and filtered. This procedure was repeated twice, and the solid was dried under reduced pressure at 120°C for 5 hours to obtain PPS Granules 2, which had a slightly lower molecular weight than that of Reference Example 1.

[0128] (Reference Example 3) Preparation of polyphenylene sulfide resin granules (PPS granules 3) The same procedure as in Reference Example 2 was carried out, except that the amount of 1,2,4-trichlorobenzene in Reference Example 2 was changed to 0.003 kmol, to obtain PPS granules 3 which contained more high-molecular-weight components and had a wider molecular weight distribution than in Reference Example 1.

[0129] (Reference Example 4) Preparation of polyphenylene sulfide resin granules (PPS granules 4) The same procedure as in Reference Example 2 was carried out, except that the reaction time at 270°C in Reference Example 2 was changed to 100 minutes and the amount of low-molecular-weight components was increased compared to Reference Example 2, to obtain PPS granules 4 containing a large amount of low-molecular-weight components.

[0130] Reference Example 5 Preparation of Polyphenylene Sulfide Resin Granules (PPS Granules 5) PPS Granules 5, which have a lower molecular weight than Reference Example 1, were obtained by performing the same operations as in Reference Example 1, except that the process of Reference Example 1, "While stirring at 400 rpm, the temperature was raised from 160°C to 220°C over 100 minutes, and the reaction was carried out at 220°C for 225 minutes. The temperature was then raised from 220°C to 255°C over 60 minutes, and 0.8 kmol of water was injected into the system over 10 minutes, and the reaction was continued for 380 minutes," was changed to "The temperature was raised from 160°C to 220°C over 100 minutes, and the reaction was carried out for 8 hours while changing the temperature stepwise so that the final temperature reached 320°C."

[0131] (Reference Example 6) Preparation of polyphenylene sulfide resin granules (PPS granules 6) PPS granules 6 having a narrower molecular weight distribution than Reference Example 1 were obtained by the same procedure as Reference Example 1, except that the reaction time at 255°C was changed to 440 minutes.

[0132] (Reference Examples 7 to 12) Method for producing PPS pellets (PPS1 to 6) PPS granules 1 to 6 produced in Reference Examples 1 to 6 were each charged into a vented co-rotating twin-screw kneading extruder (manufactured by The Japan Steel Works, Ltd., screw diameter 30 mm, screw length / screw diameter=45.5) heated to 310°C, melt-extruded for a residence time of 90 seconds at a screw rotation speed of 160 rpm, discharged in the form of a strand, cooled with water at a temperature of 25°C, and immediately cut into chips to obtain PPS1 to 6.

[0133] (Reference Example 13) Manufacturing method for PPS particle pellets (PPS particles 1) 10% by mass of spherical silica microparticles ("Seahoster" KE P50, manufactured by Nippon Shokubai Co., Ltd.) having an average particle size of 0.5 μm were mixed with 90% by mass of the PPS granules 1 prepared in Reference Example 1. The resulting mixture was melt-extruded in the same manner as in Reference Example 7 to obtain PPS particle pellets (PPS particles 1) having a particle content of 10% by mass.

[0134] Reference Example 14: Method for producing PPS particle pellets (PPS particles 2) A slurry was prepared by dispersing calcium carbonate particles having an average particle size of 1.0 μm in ethylene glycol at a concentration of 50% by mass. This slurry was filtered and then mixed with the PPS granules 1 prepared in Reference Example 1 using a Henschel mixer so that the calcium carbonate content was 10% by mass. The resulting mixture was melt-extruded in the same manner as in Reference Example 7 to obtain PPS particle pellets (PPS particles 2) with a particle content of 10% by mass.

[0135] Example 1: 75 parts by weight of the PPS pellets (PPS1) prepared in Reference Example 7, 15 parts by weight of the PPS3 prepared in Reference Example 9, and 10 parts by weight of the PPS particles 1 prepared in Reference Example 13 were dry blended and then dried under reduced pressure at 180°C for 3 hours. The mixture was then fed into an extruder, melted at 310°C under a nitrogen atmosphere, and introduced into a T-die die. The mixture was then extruded into a sheet form from the T-die die to form a molten monolayer sheet. The molten monolayer sheet was cast onto a casting drum rotating at 4.0 m / min and maintained at a surface temperature of 25°C while being cooled and solidified by electrostatic application to obtain an unstretched film. The resulting unstretched film was stretched in the longitudinal direction of the film at a stretching temperature of 100°C (MD stretching) using the difference in peripheral speed of the rolls. Then, both ends of the film were held with clips and introduced into a tenter, where it was stretched at a stretching temperature of 102 ° C. at a widthwise stretching ratio of 3.3 times (TD stretching), then stretched at a widthwise stretching ratio of 1.10 times (TD stretching 2) at 230 ° C., and heat-set for 20 seconds in a tenter heated to 235 ° C. Next, a first relaxation treatment (Rx1) was carried out in a tenter at 234 ° C. with a relaxation rate of 4.0%, followed by a second relaxation treatment (Rx2) in a tenter at 200 ° C. with a relaxation rate of 1.5%, and after cooling to room temperature, the film edges were removed to obtain an intermediate product roll of biaxially oriented polyarylene sulfide film with a width of 2000 mm. The obtained intermediate product roll was rewound, and slit 200 mm from the center of the intermediate product roll in the widthwise direction and 400 mm from the cross section to both ends, to produce a total of five film rolls. The electrolyte membrane reinforcing member was obtained by punching out an outer periphery having a width of 150 mm and a length of 200 mm, and an inner periphery having a width of 88 mm and a length of 138 mm. The physical properties and characteristics of the film are shown in Table 1.

[0136] (Examples 2 to 9, Comparative Examples 1 to 6) Biaxially oriented polyarylene sulfide films were obtained in the same manner as in Example 1, except that the raw material composition of each layer and the film-forming conditions were as shown in the table. At this time, the thickness was adjusted by adjusting the discharge rate during extrusion and the speed of the casting drum. The physical properties and evaluation results of the obtained films are shown in the table.

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[0147] The biaxially oriented polyarylene sulfide film of the present invention can be widely used as a member for fuel cells, water electrolysis devices, secondary batteries, film capacitors, motors, etc.

[0148] 1: Electrolyte membrane reinforcing member 2: Opening 3: Electrolyte membrane 4: Adhesive layer 5: Polyarylene sulfide film

Claims

1. A biaxially oriented film containing a polyarylene sulfide resin as its main constituent, in which the thickness variation in the film width direction within a 300 mm width centered at the center of the film width direction is 0.5% or more and 10.0% or less, the orientation angle from the film longitudinal direction is greater than -35° and less than 35°, greater than -90° and less than -55°, or greater than 55° and less than 90°, and the difference between the maximum and minimum values ​​of the orientation angle is greater than 0.5° and less than 20.0°.

2. The biaxially oriented polyarylene sulfide film according to claim 1, wherein the orientation angle is greater than -30° and less than 30°, or greater than -90° and less than -60°, or greater than 60° and less than 90°.

3. A biaxially oriented polyarylene sulfide film according to claim 1 or 2, in which the thickness variation in the film width direction is 0.5% or more and 6.0% or less over a 300 mm width centered at the center of the film width direction.

4. A biaxially oriented polyarylene sulfide film according to claim 1 or 2, having an elastic modulus measured at 130°C of 1.0 GPa or more in the longitudinal and transverse directions.

5. A biaxially oriented polyarylene sulfide film according to claim 1 or 2, wherein the center surface average roughness SRa of at least one surface is 10 nm or more and 100 nm or less.

6. A biaxially oriented polyarylene sulfide film according to claim 1 or 2, having a calcium ion concentration of 10 ppm by mass or less.

7. A biaxially oriented polyarylene sulfide film according to claim 1 or 2, in which in a differential molecular weight distribution curve measured by gel permeation chromatography, the vertical axis value (dw / dLogM) is 0.10 or more and 0.60 or less when the horizontal axis value (LogM) is 5.

2.

8. A biaxially oriented polyarylene sulfide film according to claim 1 or 2, in which in a differential molecular weight distribution curve measured by gel permeation chromatography, the vertical axis value (dw / dLogM) is 0.10 or more and 0.40 or less when the horizontal axis value (LogM) is 4.

0.

9. A biaxially oriented polyarylene sulfide film according to claim 1 or 2, in which in a differential molecular weight distribution curve measured by gel permeation chromatography, the vertical axis value (dw / dLogM) is 0.01 or more and 0.25 or less when the horizontal axis value (LogM) is 5.

5.

10. A biaxially oriented polyarylene sulfide film according to claim 1 or 2, having a resonance parameter (Q value) of 4,600 or more and 5,200 or less.

11. The biaxially oriented polyarylene sulfide film according to claim 1 or 2, having a minute endothermic peak temperature (T-meta) determined by differential scanning calorimetry (DSC) of 200°C or higher (melting point -20°C) or lower.

12. A biaxially oriented polyarylene sulfide film roll obtained by winding up the biaxially oriented polyarylene sulfide film according to claim 1 or 2.

13. An electrolyte membrane reinforcing member comprising the biaxially oriented polyarylene sulfide film according to claim 1.

14. An electrolyte membrane reinforcing member having a biaxially oriented polyarylene sulfide film satisfying conditions (a) and (b): (a) a calcium ion concentration of 10 ppm by mass or less, and (b) a differential molecular weight distribution curve measured by gel permeation chromatography in which the vertical axis value (dw / dLogM) is 0.15 or more and 0.60 or less when the horizontal axis value (LogM) is 5.

2.

15. An electrolyte membrane reinforcing member according to claim 14, in which in a differential molecular weight distribution curve measured by gel permeation chromatography, the vertical axis value (dw / dLogM) is 0.10 or more and 0.40 or less when the horizontal axis value (LogM) is 4.

0.

16. An electrolyte membrane reinforcing member according to claim 14 or 15, in which in a differential molecular weight distribution curve measured by gel permeation chromatography, the vertical axis value (dw / dLogM) is 0.01 or more and 0.25 or less when the horizontal axis value (LogM) is 5.

5.

17. An electrolyte membrane reinforcing member having a rectangular frame shape with an opening, wherein at least one film layer constituting the electrolyte membrane reinforcing member satisfies conditions (A) and (B): (A) the orientation angle is greater than -35° and less than 35°, greater than -90° and less than -55°, or greater than 55° and less than 90°, and (B) the difference between the maximum and minimum values ​​of the orientation angle is greater than 0.5° and less than 20°.

18. An electrolyte membrane reinforcing member according to claim 17, wherein the thickness variation of a film layer satisfying the conditions (A) and (B) measured at 10 mm intervals is 0.5% or more and 10.0% or less.

19. The electrolyte membrane reinforcing member according to claim 17 or 18, wherein the film layer satisfying the conditions (A) and (B) has a tan δ peak temperature of 120°C or higher and 160°C or lower as determined by dynamic viscoelasticity measurement.

20. The electrolyte membrane reinforcing member according to claim 17 or 18, wherein the film layer that satisfies the conditions (A) and (B) contains a polyarylene sulfide resin as a main constituent.

21. A fuel cell having an electrolyte membrane reinforcing member according to any one of claims 13, 14 and 17.

22. A water electrolysis device having the electrolyte membrane reinforcing member according to any one of claims 13, 14 and 17.

23. A metallized film comprising the biaxially oriented polyarylene sulfide film according to claim 1 and a metal layer provided on at least one side thereof.

24. A current collector foil comprising the biaxially oriented polyarylene sulfide film according to claim 1 and a metal layer provided on at least one side thereof.

25. A secondary battery using the current collecting foil according to claim 24.

26. A film capacitor using the metallized film according to claim 23.

27. Electrical insulating paper for motors, which uses the biaxially oriented polyarylene sulfide film according to claim 1.

28. A motor made using the electrical insulating paper for motors according to claim 27.

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