JP2013110048A - Laminated film for reinforcing solid polymer electrolyte membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film for reinforcing a solid polymer electrolyte membrane, having excellent workability, flexibility, and durability.SOLUTION: A laminated film for reinforcing a solid polymer electrolyte membrane is obtained by laminating a biaxial oriented polyphenylene sulfide film (A) and a fluororesin-containing layer (B). The Young's moduli in the longitudinal direction and the cross direction of the laminated film are greater than or equal to 1.0 GPa and smaller than or equal to 2.5 GPa, and the thickness of the laminated film is greater than or equal to 100 μm.

Description

  The present invention relates to a laminated film for reinforcing a polymer electrolyte membrane used in a polymer electrolyte fuel cell. More specifically, the present invention relates to a laminated film for reinforcing a solid polymer electrolyte membrane excellent in processability, flexibility and durability.

  In recent years, research on solid polymer fuel cells using a proton-conducting solid polymer membrane as an electrolyte has been advanced. Since this polymer electrolyte fuel cell has features such as a low operating temperature, small size and light weight, high efficiency, and high output density, it is expected as an in-vehicle power source or a cogeneration system for home use.

  The solid polymer membrane currently under study for this polymer electrolyte fuel cell is a proton conductive ion exchange membrane having a thickness of about 50 to 100 μm, and particularly represented by “Nafion” (a registered trademark of DuPont). Cation exchange membranes made of perfluorosulfonic acid containing sulfonic acid groups have been widely studied.

  However, in order to use fuel cells for in-vehicle power supplies and cogeneration systems, it is necessary to increase the number of stacks, reduce the membrane resistance of solid polymer membranes, manage the moisture retention of membranes, and reduce costs. Therefore, it is required to reduce the thickness of the solid polymer film, but if it is a thin film, it is difficult to handle due to lack of stiffness, and when joining to each electrode, a plurality of single cells are stacked and combined as a stack During assembly work or the like, wrinkles often occur at the peripheral edge, and the lowest mechanical strength among the constituent members of the stack is a problem in terms of productivity.

  Therefore, in Patent Document 1, the electrolyte membrane is mechanically reinforced at the peripheral portion of the fuel battery cell, and the reinforcement is airtightly bonded so that fuel gas and oxidant gas do not leak from the boundary surface with the electrolyte membrane. It is preferable to provide a frame and a reinforcing frame having required mechanical strength, corrosion resistance, etc. even at an operating temperature. For example, polycarbonate, other polyethylene terephthalate, thermosetting plastic such as glass fiber reinforced epoxy resin, titanium, etc. And the like using a corrosion-resistant metal such as carbon or carbon. Patent Document 2 discloses that a frame member having airtightness is used at the outer peripheral end of a porous body fixed on both surfaces of a solid polymer electrolyte membrane. Examples of the material include those using a thermoplastic resin such as polycarbonate, ethylene propylene copolymer, polyester, modified polyphenylene oxide, polyphenylene sulfide, or acrylonitrile styrene.

  On the other hand, Patent Document 3 discloses a solid polymer electrolyte membrane having high mechanical strength, excellent heat-resistant dimensional stability in a processing temperature / use temperature range, and excellent hydrolyzability in a high humidity use environment. A biaxially oriented polyester film containing polyethylene naphthalene dicarboxylate as a main component is disclosed as a reinforcing film.

  Patent Document 4 discloses that a seal-integrated membrane electrode assembly used in a fuel cell has a reinforcing member having rigidity higher than that of the sealing member inside the sealing member, and polyethylene resin as a resin constituting the reinforcing member. Examples include phthalate, polyethylene terephthalate, polyphenylene sulfide, polyether sulfone, polyether ether ketone, polyimide, polypropylene, and polyimide.

  As described above, as the solid polymer electrolyte reinforcing member, various resins are listed as candidates mainly from the viewpoint of mechanical strength. Among them, polyester resins may not have sufficient hydrolysis resistance because they are used in high temperature and high humidity conditions, while polyphenylene sulfide is excellent in hydrolysis resistance but lacks flexibility and workability. There was a problem.

JP 7-65847 A JP 10-199551 A JP 2007-103170 A JP 2007-250249 A

  Accordingly, an object of the present invention is to solve the various problems as described above, that is, to provide a laminated film for reinforcing a solid polymer electrolyte membrane excellent in workability, flexibility and durability. .

In order to solve the above problems, the solid polymer electrolyte membrane reinforcing laminated film of the present invention mainly has the following constitution. That is,
(1) A laminated film used for reinforcing a solid polymer electrolyte membrane, wherein the laminated film is formed by laminating a biaxially oriented polyphenylene sulfide film (A) and a layer (B) containing a fluororesin. A laminated film for reinforcing a solid polymer electrolyte membrane,
(2) The solid polymer electrolyte membrane reinforcing film according to (1), wherein the fluororesin is an ethylene-tetrafluoroethylene copolymer,
(3) The laminated film for reinforcing a solid polymer electrolyte membrane according to (1) or (2), wherein Young's modulus in the longitudinal direction and the width direction of the laminated film is 1.0 GPa or more and 2.5 GPa or less,
(4) The laminated film for reinforcing a solid polymer electrolyte membrane according to any one of (1) to (3), wherein the thickness of the laminated film is 100 μm or more.

  Since the laminated film for reinforcing a solid polymer electrolyte membrane of the present invention is excellent in processability, flexibility and durability, it can be suitably used as a film for reinforcing a solid polymer electrolyte membrane.

  Hereinafter, the laminated film for reinforcing a solid polymer electrolyte membrane of the present invention will be described.

  The polyphenylene sulfide (hereinafter sometimes abbreviated as PPS) resin constituting the biaxially oriented polyphenylene sulfide film (A) used in the present invention has a p-phenylene sulfide unit of 90 mol% or more, preferably 95 mol% or more. Resin. If the component is less than 90 mol%, the crystallinity and heat transition temperature of the polymer are low, and the heat resistance, chemical resistance, mechanical properties, etc., which are the characteristics of PPS, may be impaired.

  If the PPS resin is less than 10 mol%, preferably less than 5 mol% of the repeating unit, it may contain other copolymerizable units containing sulfide bonds. As the repeating unit of less than 10 mol%, preferably less than 5 mol% of the repeating unit, for example, a trifunctional unit, an ether unit, a sulfone unit, a ketone unit, a meta bond unit, an aryl unit having a substituent such as an alkyl group, Examples include biphenyl units, terphenylene units, vinylene units, carbonate units, and the like, and specific examples include the following structural units. One or more of these can coexist. In this case, the structural unit may be either a random type or a block type copolymerization method.

  The biaxially oriented polyphenylene sulfide film (A) used in the present invention preferably includes 90% by weight or more of the PPS resin relative to the resin constituting the A layer. If it is less than 10% by weight, it is possible to contain a thermoplastic resin other than PPS. For example, polyamide, polyetherimide, polyethersulfone, polysulfone, polyphenylene ether, polyester, polyarylate, polyamideimide, polycarbonate, Examples thereof include various polymers such as polyolefins, polyether ether ketones, fluororesins, and blends containing at least one of these polymers.

  Moreover, additives, such as an inorganic or organic filler, a lubricant, a coloring agent, a ultraviolet absorber, a compatibilizing agent, can also be included.

  The melt viscosity of the PPS resin is not particularly limited as long as melt kneading is possible, but it is preferably in the range of 100 to 2000 Pa · s at a temperature of 315 ° C. and a shear rate of 200 (1 / sec). Preferably it is the range of 200-1,000 Pa.s.

  The PPS resin used in the present invention can be prepared by various methods, for example, a method for obtaining a polymer having a relatively small molecular weight described in JP-B-45-3368, or JP-B-52-12240 and JP-A-61-61. It can be produced by a method for obtaining a polymer having a relatively large molecular weight as described in Japanese Patent No. 7332.

  In the present invention, the biaxially oriented polyphenylene sulfide film can be obtained by melt-molding the polyphenylene sulfide resin into a sheet shape, biaxial stretching, and heat treatment.

  The orientation degree of the film was 0.07 to 0.50 in the End direction and Edge direction, and 0.60 to 0.60 in the Through direction, as determined for the crystal peak of 2θ = 20 to 21 degrees by wide-angle X-ray diffraction. It is preferably in the range of 1.00.

  Moreover, the thickness of this film has the preferable range of 25-250 micrometers, More preferably, it is 50-125 micrometers.

  The biaxially oriented polyphenylene sulfide film used for the laminated film for reinforcing the solid polymer electrolyte membrane of the present invention has flexibility and seal that the breaking elongation in the longitudinal direction and the width direction of the film is 60% or more and 150% or less. From the viewpoint of sex. Here, the longitudinal direction of the film refers to the continuous film forming direction during film formation, and may be referred to as the MD direction. Further, the width direction refers to a direction orthogonal to the film continuous film forming direction, and may be referred to as a TD direction.

  Such elongation at break is more preferably 100% or more and 150% or less. When the elongation at break is less than 60%, the flexibility of the laminated film is lowered, and the sealing performance may be lowered. When the elongation at break exceeds 150%, the laminated film becomes weak and the workability may be lowered.

  The fluororesin constituting the layer (B) containing the fluororesin of the laminated film for reinforcing the solid polymer electrolyte membrane of the present invention may be any one obtained by polymerizing or copolymerizing a fluorine-containing monomer with another appropriate monomer. There is no particular limitation. Specifically, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene (FEP), polyvinylidene fluoride copolymer (PVDF), At least one selected from polychlorotrifluoroethylene copolymer (PCFE), chlorotrifluoroethylene-ethylene copolymer (ECTFE), tetrafluoroethylene-ethylene copolymer (ETFE), and the like can be used. In the present invention, ETFE is preferably used from the viewpoint of adhesiveness with PPS.

  The laminated film for reinforcing a solid polymer electrolyte membrane of the present invention is obtained by laminating a biaxially oriented polyphenylene sulfide film (A) and a layer (B) containing a fluororesin. Although it can be used in a two-layer configuration of A / B, a three-layer configuration of B / A / B is preferable from the viewpoints of workability, flexibility, and durability.

  In the present invention, a layer (C) containing another resin may be further laminated as long as the object of the present invention is not impaired.

  The ratio of the thickness of the layer (A) and the layer (B) constituting the laminated film for reinforcing the solid polymer electrolyte membrane of the present invention is (total thickness constituting the B layer) / (total thickness constituting the A layer) ) Is preferably 0.5 or more and 10 or less, more preferably 1 or more and 5 or less. If it is less than 0.5, the flexibility may not be sufficiently maintained, and if it exceeds 10, the waist of the laminated film becomes weak and workability may be reduced.

  In the laminated film for reinforcing a solid polymer electrolyte membrane of the present invention, the Young's modulus in the longitudinal direction and the width direction of the film is preferably 1.0 GPa or more and 2.5 GPa or less from the viewpoint of workability. Here, the longitudinal direction of the film refers to the continuous film forming direction during film formation, and may be referred to as the MD direction. Further, the width direction refers to a direction orthogonal to the film continuous film forming direction, and may be referred to as a TD direction.

  Such Young's modulus is more preferably 1.5 GPa or more and 2.0 GPa or less. If the Young's modulus is less than 1.0 GPa, the laminated film becomes weak and the workability may be reduced. When the Young's modulus exceeds 2.5 GPa, the flexibility cannot be sufficiently maintained, and the sealing performance may be deteriorated.

  The above-mentioned Young's modulus can be obtained by laminating the A layer and the B layer in the range of the above layer thicknesses, and further biaxially stretching the A layer by a film forming method described later.

  The thickness of the laminated film for reinforcing the solid polymer electrolyte membrane of the present invention is preferably 100 μm or more, more preferably 150 μm or more from the viewpoint of reinforcement of the polymer electrolyte membrane.

  The method of laminating the biaxially oriented polyarylene sulfide film layer (A) and the layer (B) containing a fluororesin of the present invention is not particularly limited, but a method of laminating without using an adhesive is preferable from the viewpoint of durability. Used. As a method of laminating without using an adhesive, a method of thermocompression bonding them under high temperature and high pressure, a chemical or physical process such as corona treatment, glow discharge treatment or plasma treatment on the film surface of the A layer and / or B layer. For example, a method of performing thermocompression bonding and laminating after subjecting to the target treatment can be used.

  The laminated film for reinforcing a solid polymer electrolyte membrane of the present invention is suitably used as a reinforcing film for a solid polymer electrolyte membrane of a solid polymer electrolyte fuel cell. The reinforcing film can be used by being bonded to the peripheral edge of the electrolyte membrane.

  Subsequently, although the manufacturing method of the laminated | multilayer film for solid polymer electrolyte membrane reinforcement of this invention is demonstrated taking ETFE as an example as a fluororesin, this invention is limited to the following description and is not interpreted.

  In the production of the biaxially oriented polyphenylene sulfide film used in the present invention, sodium sulfide and p-dichlorobenzene are reacted in an amide polar solvent such as N-methyl-2-pyrrolidone (NMP) at high temperature and high pressure. If necessary, a copolymer component such as trihalobenzene can be included. Caustic potash or alkali metal carboxylate is added as a polymerization degree adjusting agent, and a polymerization reaction is performed at 230 to 280 ° C. After the polymerization, the polymer is cooled, and the polymer is filtered as a water slurry through a filter to obtain a granular polymer. This is stirred in an aqueous solution such as acetate at 30 to 100 ° C. for 10 to 60 minutes, washed several times with ion exchange water at 30 to 80 ° C. and dried to obtain a PPS powder. The powder polymer is washed with NMP at an oxygen partial pressure of 10 torr or less, preferably 5 torr or less, then washed several times with ion exchange water at 30 to 80 ° C., and dried under a reduced pressure of 5 torr or less. Since the polymer thus obtained is a substantially linear PPS polymer, stable stretching and film formation are possible.

  After the powdery or granular polymer thus obtained is pelletized and vacuum-dried at 180 ° C for 3 hours or more, the molten part of the extruder is heated to a temperature of 300 to 350 ° C, preferably 320 to 340 ° C. throw into. Thereafter, the molten polymer passed through the extruder is passed through a filter, and the molten polymer is discharged into a sheet form using a die of a T die. The set temperature of the filter part and the die is preferably 3 to 20 ° C higher than the temperature of the melting part of the extruder, more preferably 5 to 15 ° C. This sheet-like material is brought into close contact with a cooling drum having a surface temperature of 20 to 70 ° C. to be cooled and solidified to obtain a substantially non-oriented unstretched PPS film.

  Next, the sheet is stretched in the multi-stage of 1 to 2 or more stages (MD stretching) in the longitudinal direction 2 to 4 times, preferably 3 to 4 times, more preferably 3 to 3.4 times. The stretching temperature is in the range of Tg (glass transition temperature of PPS) to (Tg + 40) ° C., preferably (Tg + 5) to (Tg + 30) ° C.

  Following MD stretching, the film is stretched in multiple stages of 1 to 2 or more stages in the width direction (TD direction) by a tenter or the like, preferably 3 to 3.5 times (TD stretching). The stretching temperature is in the range of Tg (glass transition temperature of PPS) to (Tg + 30) ° C., preferably (Tg + 5) to (Tg + 20) ° C.

  From the viewpoint of flexibility, the biaxially oriented PPS film of the present invention is preferably 13 times or less, more preferably 12 times or less, and more preferably 11.5 times or less as an area magnification (product of MD direction magnification and TD direction magnification). Further preferred.

  Next, this stretched film is heat-set under tension. In the present invention, a method carried out in steps of two or more different temperatures is a preferred embodiment from the viewpoint of thickness unevenness in the film width direction, orientation unevenness, and flatness. The maximum temperature for heat setting in the first stage is 160 to 220 ° C., preferably 180 to 220 ° C., and the treatment time is 1 to 15 seconds, preferably 1 to 10 seconds. Subsequently, the maximum temperature of the subsequent heat setting is 240 to 280 ° C, preferably 260 to 280 ° C. Furthermore, this film is subjected to a relaxation treatment in the width direction at 240 to 280 ° C, more preferably 260 to 280 ° C. The relaxation rate is preferably 0.1 to 8%, more preferably 2 to 5%.

  The ETFE layer used in the present invention can be formed by using a known method of melt-extrusion of ETFE at 320 ° C. to 350 ° C. and casting on a cooling drum, or a commercially available film.

Next, in order to laminate the biaxially oriented PPS film and the ETFE layer, it is possible to use a method in which the adhesive surfaces of the PPS film and the ETFE film are preliminarily plasma-treated and then thermocompression bonded under high temperature and high pressure. In this case, a temperature of 150 to 250 ° C. and a pressure of 5 to 50 kg / cm ² are preferable.

  In the case of three-layer lamination, after biaxially oriented PPS film and ETFE film are laminated, another layer of ETFE may be laminated on the PPS side, or three layers may be laminated simultaneously.

  The laminated film thus obtained can be suitably used as a reinforcing film for a solid polymer electrolyte membrane of a solid polymer electrolyte fuel cell, and in particular, an electrolyte membrane that requires processability, flexibility, and durability. Suitable as a reinforcing member for the peripheral edge.

The measurement method or evaluation method of physical property values or properties is as follows.
(1) Young's modulus Using an Instron type tensile tester (Orientec AMF / RTA-100) according to the following method prescribed in ASTM-D882 (1999), a sample film with a width of 10 mm is placed between chucks. The length is set to 50 mm, and a tensile test is performed at a temperature of 25 ° C. and an atmospheric condition of 55% RH at a tensile speed of 300 mm / min.

  The Young's modulus is obtained by performing arithmetic average for five measurements in the film longitudinal direction and the width direction, respectively.

Measuring device: Orientec Co., Ltd. film strong elongation automatic measuring device “Tensilon AMF / RTA-100”
Sample size: width 10mm x length 150mm
Tensile speed: 300 mm / min Measurement environment: 25 ° C., 55% RH
(2) Elongation at break Using a Instron type tensile tester (Orientec AMF / RTA-100) according to the method specified in ASTM-D882 (1999), a sample film with a width of 10 mm was measured between chucks. A tensile test is performed at a temperature of 25 ° C. and a relative humidity of 55% (55% RH) at a tensile speed of 300 mm / min.

  The elongation at break is determined by arithmetically averaging five measurements each in the longitudinal direction and the width direction of the film.

Measuring device: Orientec Co., Ltd. film strong elongation automatic measuring device “Tensilon AMF / RTA-100”
Sample size: width 10mm x test length 150mm
Tensile speed: 300 mm / min Measurement environment: 25 ° C., 55% RH
(3) Hydrolyzability (durability)
A strip-shaped sample piece obtained by cutting the sample film into a width of 10 mm and a length of 150 mm is suspended with a stainless steel clip in an environmental test machine set to 121 ° C., 2 atm, wet saturation mode, and 100% RH. Thereafter, sample pieces are taken out every 10 hours and the breaking strength is measured. About each direction about a film longitudinal direction and the width direction, breaking strength was measured by n number = 5 every processing time 10 hours, the average value of each direction was calculated | required, and breaking strength retention represented by following formula (1) Was calculated. Furthermore, the average value of the breaking strength retention in the longitudinal direction and the transverse direction for each period is obtained, the half-life time until the breaking strength retention reaches 50% of the initial value is obtained, and the hydrolysis resistance is evaluated according to the following criteria. did.

○: Half life of breaking strength retention is 300 hours or more ×: Half life of breaking strength retention is less than 300 hours
Measuring device: Orientec Co., Ltd. film strong elongation automatic measuring device “Tensilon AMF / RTA-100”
Tensile speed: 300 mm / min Measurement environment: 25 ° C., 55% RH
Breaking strength retention ratio (%) = (breaking strength X / initial breaking strength X0) × 100 (1)
(In the formula, the breaking strength X is the breaking strength after treatment for a predetermined time under the conditions of 121 ° C., 2 atm, 100% RH (unit: MPa), and the breaking strength X0 is the initial breaking strength before treatment (unit: MPa). Respectively)
(4) Laminated film thickness Film thickness was measured at 30 g of needle pressure using an electronic micrometer (trade name “K-312A type” manufactured by Anritsu Co., Ltd.).
(5) Thickness of each layer The thickness of each layer of the laminated film is determined by embedding a small piece of film in an epoxy resin (trade name “Epomount” manufactured by Refine Tech Co., Ltd.) and embedding using a Microtome 2050 manufactured by Reichert-Jung. The whole resin was sliced to a thickness of 50 nm and measured by an accelerating voltage of 100 KV using a transmission electron microscope (LEM-2000).
(6) Workability A 100 mm square perfluorosulfonic acid resin (manufactured by DuPont: Nafion 117) is used as the electrolyte membrane, and a frame-shaped laminated film (outer periphery 100 mm × 100 mm, inner periphery 80 mm × 80 mm) is stacked on both sides. Joining was performed by hot pressing at 140 ° C., and the workability was evaluated according to the following criteria.
Workability ○: No changes such as wrinkles, tearing, and breakage are observed in the electrolyte membrane, and the reinforcement performance is excellent with no deformation or misalignment of the reinforcing member due to pressurization.
X: At least one of wrinkles, tears and breakage is observed in the electrolyte membrane, and at least one of deformation and displacement of the reinforcing member due to pressurization is observed, and the reinforcing performance is not sufficient (7) Sealability ( Flexibility)
A 100 mm square perfluorosulfonic acid resin (manufactured by DuPont: Nafion 117) is used as the electrolyte membrane, and frame-shaped laminated films (outer circumference 100 mm × 100 mm, inner circumference 80 mm × 80 mm) are stacked on both sides and heated at 140 ° C. And assembled into a fuel cell, submerged in water, and compressed air was sent to one side of the cell so that bubbles were generated from the opposite side. At that time, the pressure of the compressed air was gradually increased from 0 MPa.

  The pressure at which bubbles were generated was determined, and the sealing performance was evaluated by relative evaluation with respect to the case where the ETFE film of Comparative Example 2 was used.

○: 1 time or more in comparison with ETFE film Δ: 0.5 time or more and less than 1 time in comparison with ETFE film ×: Less than 0.5 time in comparison with ETFES film

(Reference Example 1) Polymerization of PPS Resin In a 70 liter autoclave equipped with a stirrer, 8,267.37 g (70.00 mol) of 47.5% sodium hydrosulfide, 2,957.21 g (70.21 g) of 96% sodium hydroxide were added. 97 mol), 11,434.50 g (115.50 mol) of N-methyl-2-pyrrolidone (NMP), 2,583.00 g (31.50 mol) of sodium acetate, and 10,500 g of ion-exchanged water, The mixture was gradually heated to 245 ° C. over about 3 hours while passing nitrogen at normal pressure, and after distilling 14,780.1 g of water and 280 g of NMP, the reaction vessel was cooled to 160 ° C. The residual water content in the system per 1 mol of the charged alkali metal sulfide was 1.06 mol including the water consumed for the hydrolysis of NMP. The amount of hydrogen sulfide scattered was 0.02 mol per mol of the charged alkali metal sulfide.

  Next, 10,235.46 g (69.63 mol) of p-dichlorobenzene and 9,09.0.00 g (91.00 mol) of NMP were added, the reaction vessel was sealed under nitrogen gas, and the mixture was stirred at 240 rpm. The temperature was raised to 238 ° C. at a rate of 6 ° C./min. After reacting at 238 ° C. for 95 minutes, the temperature was raised to 270 ° C. at a rate of 0.8 ° C./min. After reacting at 270 ° C. for 100 minutes, 1,260 g (70 mol) of water was injected over 15 minutes and cooled to 250 ° C. at a rate of 1.3 ° C./minute. Then, after cooling to 200 ° C. at a rate of 1.0 ° C./min, it was rapidly cooled to near room temperature.

  The contents were taken out, diluted with 26,300 g of NMP, the solvent and solid matter were filtered off with a sieve (80 mesh), and the resulting particles were washed with 31,900 g of NMP and filtered off. This was washed several times with 56,000 g of ion-exchanged water, filtered and then washed with 70,000 g of 0.05 wt% aqueous calcium acetate and filtered. After washing with 70,000 g of ion-exchanged water and filtering, the resulting hydrous PPS particles were dried with hot air at 80 ° C. and dried under reduced pressure at 120 ° C. The obtained PPS resin had a melt viscosity of 200 Pa · s (310 ° C., shear rate of 200 / s), a glass transition temperature of 90 ° C., and a melting point of 280 ° C.

Example 1
Full flight in which 100 parts by weight prepared in Reference Example 1 and 0.3 parts by weight of calcium carbonate powder having an average particle size of 1.2 μm were blended and dried under reduced pressure at 180 ° C. for 3 hours, and then the molten part was heated to 320 ° C. To a single screw extruder. The polymer melted by the extruder is filtered through a filter set at a temperature of 330 ° C., then melt-extruded from a die of a T die set at a temperature of 310 ° C., and solidified by cooling while applying an electrostatic charge to a cast drum having a surface temperature of 25 ° C. And the unstretched film was produced.

  This unstretched film was stretched at a magnification of 3.5 times in the longitudinal direction of the film at a temperature of 101 ° C. using a difference in peripheral speed of the roll using a longitudinal stretching machine composed of a plurality of heated roll groups. . Thereafter, both ends of the film are gripped with clips and guided to a tenter, stretched in the width direction of the film at a stretching temperature of 101 ° C. and a stretching ratio of 3.5 times, and subsequently heat treated at a temperature of 200 ° C. for 4 seconds (1 Step heat treatment was performed, followed by heat treatment at 260 ° C. for 4 seconds (second step heat treatment). Subsequently, after 5% relaxation treatment in the transverse direction for 4 seconds in a relaxation treatment zone at 260 ° C., the film edge was removed after cooling to room temperature, and a biaxially oriented PPS film having a thickness of 50 μm and a breaking elongation of 100% Was made.

The obtained biaxially oriented PPS film was plasma treated with a commercially available 50 μm thick ETFE (“Aflex” manufactured by Asahi Glass Co., Ltd.) on the side where the biaxially oriented PPS and ETFE are in contact, and then ETFE / biaxially oriented PPS. / ETFE was laminated in this order, and a laminated film was obtained by applying a hot press roll at a temperature of 200 ° C. and a pressure of 20 kg / cm ² .

  The measurement and evaluation results on the characteristics of the obtained laminated film are as shown in Table 1. This laminated film was excellent in durability, workability, and flexibility.

(Example 2)
A laminated film was produced in the same manner as in Example 1 except that the thickness of the biaxially oriented PPS film was changed to 75 μm in Example 1.

  The measurement and evaluation results on the characteristics of the obtained laminated film are as shown in Table 1. This laminated film was excellent in durability, workability, and flexibility.

(Example 3)
A laminated film was produced in the same manner as in Example 1, except that the thickness of the biaxially oriented PPS film was changed to 25 μm.

  The measurement and evaluation results on the characteristics of the obtained laminated film are as shown in Table 1. This laminated film was excellent in durability, workability, and flexibility.

Example 4
A laminated film was produced in the same manner as in Example 1 except that the thickness of the 125 μm-thick biaxially oriented PPS film was 125 μm and the thickness of the 25 μm-thick ETFE layer was 25 μm.

  The measurement and evaluation results on the characteristics of the obtained laminated film are as shown in Table 1. This laminated film was excellent in durability, workability, and flexibility.

(Example 5)
The PPS unstretched film obtained in Example 1 was stretched in the machine direction at a magnification of 4.0 times, and then stretched in the width direction of the film at a stretch ratio of 3.7 times. Thus, a biaxially oriented PPS film having a thickness of 50 μm and a breaking elongation of 60% was produced.

  A laminated film was produced in the same manner as in Example 1 except that the biaxially oriented PPS film obtained above was used.

  The measurement and evaluation results on the characteristics of the obtained laminated film are as shown in Table 1. This laminated film was excellent in durability, workability, and flexibility.

(Comparative Example 1)
A biaxially oriented PPS film having a thickness of 100 μm was produced in the same manner as in Example 1.

  The measurement and evaluation results for the properties of the obtained biaxially oriented PPS film were as shown in Table 1. When an evaluation was conducted using only this biaxially oriented PPS film without providing an ETFE layer, the durability and workability were excellent, but the flexibility deteriorated.

(Comparative Example 2)
The measurement and evaluation results on the characteristics when only ETFE having a thickness of 100 μm was used are as shown in Table 1. This ETFE film was excellent in durability and flexibility, but the workability deteriorated.

(Comparative Example 3)
A laminated film was prepared in the same manner as in Example 1 except that a polyimide film (“KAPTON” manufactured by DuPont) having a thickness of 50% and a fracture elongation of 50% was laminated with ETFE instead of the biaxially oriented PPS film in Example 1. did.

  The measurement and evaluation results on the properties of the obtained laminated film are as shown in Table 1. This laminated film is excellent in workability and flexibility, but the durability deteriorated.

Since the laminated film for reinforcing a solid polymer electrolyte membrane of the present invention is excellent in processability, flexibility and durability, it can be suitably used as a film for reinforcing a solid polymer electrolyte membrane.

Warning 1

Claims (4)

A laminated film used for reinforcing a solid polymer electrolyte membrane, wherein the laminated film is formed by laminating a biaxially oriented polyphenylene sulfide film (A) and a layer (B) containing a fluororesin. A laminated film for reinforcing solid polymer electrolyte membranes. The solid polymer electrolyte membrane reinforcing film according to claim 1, wherein the fluororesin is an ethylene-tetrafluoroethylene copolymer. The laminated film for reinforcing a solid polymer electrolyte membrane according to claim 1 or 2, wherein Young's modulus in the longitudinal direction and the width direction of the laminated film is 1.0 GPa or more and 2.5 GPa or less. The laminated film for reinforcing a solid polymer electrolyte membrane according to any one of claims 1 to 3, wherein the thickness of the laminated film is 100 µm or more.