Insulating materials for electrochemical devices

Abstract

To provide an insulating material for an electrochemical device that can maintain their insulation properties even at high temperatures.SOLUTION: An insulating material for an electrochemical device includes a polytetrafluoroethylene composition containing polytetrafluoroethylene, which is a homopolymer of tetrafluoroethylene or a modified polytetrafluoroethylene containing tetrafluoroethylene units and 1.0 mass% or less of modified monomer units.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to an insulating member for an electrochemical device. [Background technology]

[0002] BACKGROUND ART It is known that resins such as perfluoroalkoxyalkane (PFA) are used as insulating members and sealing members for electrochemical devices such as lithium ion secondary batteries (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-174732 [Patent Document 2] International Publication No. 2020 / 066050 [Patent Document 3] International Publication No. 2014 / 049645 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present disclosure is to provide an insulating member for an electrochemical device that can maintain its insulating properties even at high temperatures. [Means for solving the problem]

[0005] The present disclosure (1) is an insulating member for an electrochemical device, comprising a polytetrafluoroethylene composition containing polytetrafluoroethylene, which is a homopolymer of tetrafluoroethylene or a modified polytetrafluoroethylene containing tetrafluoroethylene units and 1.0 mass % or less of modified monomer units.

[0006] The present disclosure (2) is the insulating member according to the present disclosure (1), wherein the polytetrafluoroethylene composition has a heat of crystallization of 50 J / g or less.

[0007] The present disclosure (3) is the insulating member according to the present disclosure (1) or (2), wherein the polytetrafluoroethylene composition exhibits non-melt moldability.

[0008] The present disclosure (4) is an insulating member in any combination with any of the present disclosures (1) to (3), in which the polytetrafluoroethylene is the modified polytetrafluoroethylene.

[0009] The present disclosure (5) is an insulating member in any combination with any of the present disclosures (1) to (4), in which the modified monomer is perfluoro(propyl vinyl ether).

[0010] The present disclosure (6) is an insulating member in any combination with any of the present disclosures (1) to (5), wherein the electrochemical device comprises a non-aqueous electrolyte.

[0011] The present disclosure (7) is an insulating member that can be arbitrarily combined with any of the present disclosures (1) to (6) that are gaskets.

[0012] The present disclosure (8) is an insulating member in any combination with any of the present disclosures (1) to (7), wherein the content of modified monomer units in the modified polytetrafluoroethylene is 0.20 mass % or less relative to all polymerized units.

[0013] The present disclosure (9) is a polytetrafluoroethylene composition having a content of 99.0% by mass or more relative to the polytetrafluoroethylene composition, In the insulating member according to the present disclosure (8), the content of the polytetrafluoroethylene composition is 99.0 mass % or more relative to the insulating member.

[0014] The present disclosure (10) is the insulating member according to the present disclosure (9), which has a melt flow rate of less than 0.10 g / 10 min.

[0015] The present disclosure (11) is an insulating member for electrochemical devices that exhibits non-melt formability.

[0016] The present disclosure (12) has a melt flow rate of less than 0.10 g / 10 min, The insulating member according to the present disclosure (11) contains polytetrafluoroethylene.

[0017] The present disclosure (13) is an insulating member in any combination with any of the present disclosures (1) to (12), wherein the electrochemical device is a lithium ion battery or a sodium ion battery.

[0018] The present disclosure (14) is an insulating member that is an optional combination with any of the present disclosures (1) to (13) having a heat of fusion of 50 J / g or more. [Effects of the Invention]

[0019] According to the present disclosure, it is possible to provide an insulating member for an electrochemical device that can maintain its insulating properties even at high temperatures. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 2 is a schematic cross-sectional view showing an example of the configuration of a portion of an electrochemical device including an insulating member (gasket). [Figure 2] FIG. 2 is a schematic cross-sectional view showing an example of the configuration of a portion of an electrochemical device including an insulating member (gasket). [Figure 3] FIG. 2 is a schematic cross-sectional view showing an example of the configuration of a portion of an electrochemical device including an insulating member (gasket). [Figure 4] 1A to 1C are diagrams schematically illustrating a procedure for preparing a test assembly used for measuring insulation resistance. [Figure 5] 1A to 1C are diagrams schematically illustrating a procedure for preparing a test assembly used for measuring insulation resistance. [Figure 6] FIG. 1 is a schematic diagram of a test assembly used for measuring insulation resistance. [Figure 7] FIG. 2 is a diagram schematically illustrating one step of measuring insulation resistance. [Figure 8] FIG. 1 is a schematic diagram of a permeation test jig used in a water vapor permeation test. DETAILED DESCRIPTION OF THE INVENTION

[0021] The present disclosure will be specifically described below.

[0022] The present disclosure provides an insulating member for electrochemical devices (hereinafter also referred to as insulating member (1) of the present disclosure) containing a PTFE composition containing PTFE, which is a homopolymer of tetrafluoroethylene (TFE) or modified polytetrafluoroethylene (PTFE) containing TFE units and 1.0 mass % or less of modified monomer units.

[0023] In this specification, unless otherwise specified, the insulating member (1) of the present disclosure and the insulating member (2) of the present disclosure described below will be collectively referred to as the "insulating member of the present disclosure."

[0024] The insulating member (1) of the present disclosure contains a specific PTFE composition, and is therefore able to maintain its insulating properties even at high temperatures. In electrochemical devices requiring high output, such as lithium-ion power batteries, many cells are generally connected in parallel or series in close proximity. In such a configuration, even if a nearby cell catches fire or the temperature of the cell becomes abnormally high (for example, 400°C or higher), the insulating member (1) of the present disclosure can maintain good insulation properties and prevent short circuits of the cells and between the components of the cells.

[0025] The PTFE in the insulating member (1) of the present disclosure is a homopolymer of TFE or a modified PTFE. The modified PTFE is preferred because it has better insulating properties at high temperatures and also has low water vapor permeability.

[0026] The modified PTFE contains TFE units and 1.0% by mass or less of modified monomer units. The amount of TFE units may be 99.0% by mass or more. Alternatively, the modified PTFE may consist solely of TFE units and modified monomer units.

[0027] The modified PTFE preferably has a modified monomer unit content of 0.00001 to 1.0% by mass relative to the total polymerized units, in order to further improve insulating properties at high temperatures and low water vapor permeability. The lower limit of the modified monomer unit content is preferably 0.0001% by mass, more preferably 0.001% by mass, even more preferably 0.005% by mass, and particularly preferably 0.010% by mass. The upper limit of the modified monomer unit content is preferably 0.90% by mass, more preferably 0.80% by mass, more preferably 0.50% by mass, even more preferably 0.40% by mass, even more preferably 0.30% by mass, even more preferably 0.20% by mass, and particularly preferably 0.10% by mass. In this specification, the modified monomer unit means a part of the molecular structure of PTFE that is derived from the modified monomer.

[0028] The content of each of the above-mentioned polymerized units can be calculated by appropriately combining NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer.

[0029] The modifying monomer is not particularly limited as long as it is copolymerizable with TFE, and examples thereof include perfluoroolefins such as hexafluoropropylene (HFP), hydrogen-containing fluoroolefins such as trifluoroethylene and vinylidene fluoride (VDF), perhaloolefins such as chlorotrifluoroethylene (CTFE), perfluorovinyl ether, perfluoroallyl ether, (perfluoroalkyl)ethylene, ethylene, etc. The modifying monomer used may be one type or multiple types.

[0030] The perfluorovinyl ether is not particularly limited, and examples thereof include perfluorovinyl ethers represented by the following general formula (A): CF2=CF-ORf 1 (A) (In the formula, Rf 1represents a perfluoroorganic group. ) and perfluorounsaturated compounds represented by the formula (I) are included. In this specification, the "perfluoroorganic group" refers to an organic group in which all hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms. The perfluoroorganic group may have an ether oxygen.

[0031] The perfluorovinyl ether may be, for example, a compound represented by the general formula (A) in which Rf 1 is a perfluoroalkyl group having 1 to 10 carbon atoms. The number of carbon atoms in the perfluoroalkyl group is preferably 1 to 5.

[0032] Examples of the perfluoroalkyl group in the PAVE include a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, and a perfluorohexyl group.

[0033] The perfluorovinyl ether further includes a compound represented by the general formula (A) in which Rf 1 is a perfluoro(alkoxyalkyl) group having 4 to 9 carbon atoms, Rf 1 is the following formula:

[0034] [ka]

[0035] (wherein m represents 0 or an integer of 1 to 4), Rf 1 is the following formula:

[0036] [ka]

[0037] (wherein n represents an integer of 1 to 4).

[0038] The (perfluoroalkyl)ethylene [PFAE] is not particularly limited, and examples thereof include (perfluorobutyl)ethylene [PFBE] and (perfluorohexyl)ethylene.

[0039] Examples of hydrogen-containing fluoroolefins include CH2=CF2, CFH=CH2, CFH=CF2, CH2=CFCF3, CH2=CHCF3, CHF=CHCF3 (E-form), and CHF=CHCF3 (Z-form).

[0040] Examples of perfluoroallyl ethers include those represented by the general formula (B): CF2=CF-CF2-ORf 2 (B) (In the formula, Rf 2 represents a perfluoroorganic group.

[0041] Above Rf 2 is preferably a perfluoroalkyl group having 1 to 10 carbon atoms or a perfluoroalkoxyalkyl group having 1 to 10 carbon atoms. The perfluoroallyl ether is preferably at least one selected from the group consisting of CF2=CF-CF2-O-CF3, CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9, more preferably at least one selected from the group consisting of CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9, and even more preferably CF2=CF-CF2-O-CF2CF2CF3.

[0042] As the modified monomer, in terms of further improving insulating properties at high temperatures and low water vapor permeability, at least one selected from the group consisting of PAVE, PFAE, HFP, and CTFE is preferred, at least one selected from the group consisting of PAVE and HFP is more preferred, PAVE is even more preferred, and perfluoro(propyl vinyl ether) [PPVE] is even more preferred.

[0043] The PTFE may have a core-shell structure. Examples of PTFE having a core-shell structure include modified PTFE particles containing a core of high molecular weight PTFE and a shell of lower molecular weight PTFE or modified PTFE. Examples of such modified PTFE include the PTFE described in JP-A-2005-527652.

[0044] The PTFE may be PTFE obtained by emulsion polymerization or PTFE obtained by suspension polymerization. In terms of improving low water vapor permeability, PTFE obtained by emulsion polymerization is preferred, and unsintered PTFE (which has not been heated to a temperature above its melting point) obtained by emulsion polymerization is more preferred.

[0045] In order to further improve the insulating properties at high temperatures, the PTFE composition preferably has an endothermic peak temperature of 333°C or higher, more preferably 335°C or higher, even more preferably 337°C or higher, and even more preferably 340°C or higher, and preferably 350°C or lower, and more preferably 346°C or lower. The endothermic peak temperature is the temperature corresponding to the minimum point in the heat of fusion curve obtained by performing differential scanning calorimetry (DSC) at a heating rate of 10°C / min on a PTFE composition that has not been heated to a temperature of 300°C or higher. When there are two or more minimum points in one melting peak, each of them is regarded as an endothermic peak temperature.

[0046] In order to further improve the insulating properties at high temperatures, the PTFE composition preferably has a melting point of 315°C or higher, more preferably 320°C or higher, even more preferably 323°C or higher, and even more preferably 325°C or higher, and preferably 335°C or lower, and more preferably 330°C or lower. The melting point is the temperature corresponding to the minimum point in the heat of fusion curve obtained by subjecting a PTFE composition that has been heated to a temperature of 300°C or higher to differential scanning calorimetry (DSC) at a heating rate of 10°C / min.

[0047] The PTFE composition may be a PTFE composition that has not been completely sintered. A PTFE composition that has not been completely sintered has a large heat of fusion and may take a long time to completely melt, so this has the advantage that the temperature rise during heat generation can be delayed, and it is possible to prevent the composition from reaching an abnormally high temperature in a short time.

[0048] The PTFE composition preferably has a heat of fusion of 27 J / g or more, more preferably 30 J / g or more, even more preferably 33 J / g or more, and particularly preferably 60 J / g or more, in that it can delay the temperature rise during heat generation and prevent the temperature from reaching an abnormally high temperature in a short period of time, and may also have a heat of fusion of 90 J / g or less, or may have a heat of fusion of 80 J / g or less. The heat of fusion is a value measured using a differential scanning calorimeter (DSC).

[0049] In order to further improve the insulating properties at high temperatures, the PTFE composition preferably has a heat of crystallization of 50 J / g or less, more preferably 40 J / g or less, even more preferably 30 J / g or less, and even more preferably 25 J / g or less, and may also have a heat of crystallization of 10 J / g or more, or 15 J / g or more. The heat of crystallization is a value measured using a differential scanning calorimeter (DSC).

[0050] In order to further improve the insulating properties at high temperatures, the PTFE composition has a thermal decomposition temperature of preferably 400° C. or higher, more preferably 430° C. or higher, and even more preferably 450° C. or higher. Alternatively, the thermal decomposition temperature may be 600° C. or lower, 550° C. or lower, or 520° C. or lower. The thermal decomposition temperature is the temperature at which the mass loss of the sample reaches 1% by mass when measured using a thermogravimetric and differential thermal analyzer (STA7200 manufactured by Hitachi High-Tech Science Corporation) in an air atmosphere at a heating rate of 10°C / min.

[0051] The PTFE composition has a melt viscosity of 1.0×10 at 380°C, which further improves the insulating properties at high temperatures. 7 Pa·s or more is preferable, and 1.0×10 8 It is more preferable that the viscosity is 1.0×10 Pa·s or more. 11 Pa·s or less, and 5.0×10 10 It may be less than Pa·s. The melt viscosity is measured using a melt viscoelasticity measuring device MCR302 (manufactured by Anton Paar Japan Co., Ltd.) using a parallel plate measuring jig with a diameter of 7 mm, and the complex viscosity measured at a deformation rate of 0.3%, a sample thickness of 0.5 mm, a temperature of 380°C, and a frequency of 0.01 radians per second is defined as the melt viscosity.

[0052] In order to further improve the insulating properties at high temperatures, the PTFE composition preferably has a standard specific gravity (SSG) of 2.200 or less, more preferably 2.190 or less, even more preferably 2.180 or less, and even more preferably 2.175 or less, and may also be 2.130 or more, 2.140 or more, or 2.150 or more. The SSG is measured by the water displacement method according to ASTM D 792 using a sample molded according to ASTM D 4895 89.

[0053] The PTFE composition preferably has non-melt-processability, which means that the melt flow rate cannot be measured at a temperature higher than the melting point in accordance with ASTM D-1238 and D-2116, in other words, the PTFE composition does not easily flow even in the melting temperature range.

[0054] The PTFE composition preferably exhibits non-melt moldability, which will be described later.

[0055] The PTFE composition may be a sintered PTFE composition or an unsintered PTFE composition, or may be a PTFE composition that has been heated to a temperature equal to or higher than its melting point or may be a PTFE composition that has not been heated to a temperature equal to or higher than its melting point. PTFE compositions that have not been heated above their melting point have the property of being stretchy and soft when processed into raw tape. This allows them to easily conform to the shape of the part when wrapped around it, making them easy to attach to parts with simple shapes as well as complex shapes, and they have the advantage of providing insulation to the area around the part.

[0056] The PTFE composition may contain components other than the PTFE, but preferably consists essentially of the PTFE. This allows the effects of the PTFE to be significantly exhibited. "Consisting essentially of the PTFE" means that the PTFE content is 70% by mass or more relative to the PTFE composition. The content of the PTFE in the PTFE composition is preferably 90.0% by mass or more, more preferably 95.0% by mass or more, even more preferably 99.0% by mass or more, particularly preferably 99.9% by mass or more, and most preferably 99.95% by mass or more. It is also preferable that the PTFE composition consists solely of the PTFE.

[0057] The PTFE composition may contain a filler or the like. The filler is preferably an insulating filler, and conductive fillers are not preferred. Examples of the filler include known insulating fillers such as aluminum oxide, silicon oxide, magnesium oxide, anhydrous magnesium carbonate, magnesium hydroxide, silicon oxide, silicon nitride, boron nitride, and aluminum nitride, with magnesium oxide, aluminum nitride, and boron nitride being preferred.

[0058] The insulating member (1) of the present disclosure may contain components other than the PTFE composition, but preferably consists essentially of the PTFE composition. This allows the effects of the PTFE composition to be significantly exhibited. "Consisting essentially of the PTFE composition" means that the content of the PTFE composition is 70% by mass or more relative to the insulating member. The content of the PTFE composition in the insulating member is preferably 90.0% by mass or more, more preferably 95.0% by mass or more, even more preferably 99.0% by mass or more, particularly preferably 99.9% by mass or more, and most preferably 99.95% by mass or more. It is also preferable that the insulating member (1) of the present disclosure consists of the above-mentioned PTFE composition alone.

[0059] The insulating member (1) of the present disclosure preferably exhibits non-melt formability, which will be described later.

[0060] The insulating member (1) of the present disclosure can be produced by molding a raw material composition containing raw material PTFE into a desired shape. The form of the raw material composition is not limited and may be a powder, a dispersion liquid, or the like, but is preferably a powder.

[0061] The raw material PTFE can be produced by emulsion polymerization or suspension polymerization.

[0062] The emulsion polymerization can be carried out by a known method. For example, an aqueous dispersion containing the PTFE particles (primary particles) can be obtained by emulsion polymerization of the monomers (TFE and, if necessary, a modified monomer) necessary for constituting the PTFE in an aqueous medium in the presence of an anionic fluorine-containing surfactant and a polymerization initiator. In the emulsion polymerization, a chain transfer agent, a buffer, a pH adjuster, a stabilizing aid, a dispersion stabilizer, a radical scavenger, etc. may be used as needed.

[0063] The resulting aqueous dispersion is coagulated to obtain a wet powder, which is then dried to obtain a raw material PTFE powder. Coagulation and drying can be performed by known methods.

[0064] Suspension polymerization can be carried out, for example, by charging a reactor with a monomer such as TFE, an aqueous medium, and other additives as necessary, stirring the contents of the reactor, maintaining the reactor at a predetermined polymerization temperature, and then adding a predetermined amount of polymerization initiator to initiate the polymerization reaction. After the start of the polymerization reaction, additional monomers such as TFE, polymerization initiators, chain transfer agents, etc. may be added depending on the purpose.

[0065] The suspension-polymerized particles obtained may be washed and then pulverized, or the suspension-polymerized particles obtained may be pulverized while being washed, to produce pulverized particles.

[0066] The wet pulverized particles may be dehydrated and further dried. Drying is carried out for the purpose of removing moisture from the pulverized particles obtained by pulverization.

[0067] After the suspension polymerized particles are pulverized, the pulverized particles obtained may be classified by a known method such as air classification.

[0068] The resulting pulverized particles may be granulated by a known granulation method.

[0069] By adjusting the conditions of polymerization and post-treatment, the physical properties of the resulting PTFE can be adjusted. For example, in emulsion polymerization, the endothermic peak temperature can be increased, the standard specific gravity can be lowered, or the melt viscosity can be increased by reducing the amount of polymerization initiator used, reducing the amount of chain transfer agent used, or using a radical scavenger. In the post-treatment of emulsion polymerization, the decomposition temperature can be increased by setting the drying temperature to 150°C or higher. In suspension polymerization, the endothermic peak temperature can be increased, the standard specific gravity can be lowered, and the melt viscosity can be increased by reducing the amount of polymerization initiator used, reducing the amount of chain transfer agent used, or preferably not using any chain transfer agent at all. In post-treatment, the decomposition temperature can be increased by washing and setting the drying temperature to 150°C or higher.

[0070] The method for molding the raw material composition is not particularly limited, and any known molding method can be used.

[0071] When using a powder obtained by emulsion polymerization, for example, the powder of the raw material composition and an extrusion aid can be mixed and paste extrusion molded. The extrusion aid can be removed by drying. It is also preferable to compress the powder of the raw material composition. A dispersion of the raw material composition may be applied to a substrate such as glass cloth and dried. If necessary, firing may be performed.

[0072] When using powder obtained by suspension polymerization, molding methods such as compression molding, ram extrusion molding, isostatic compression molding, etc., can be used. If necessary, calcination may be carried out. The PTFE molded body may be processed by machining such as cutting to produce a molded body having a desired shape. For example, a PTFE sheet can be obtained by cutting the PTFE molded body.

[0073] The present disclosure also provides an insulating member for electrochemical devices that exhibits non-melt formability (hereinafter also referred to as insulating member (2) of the present disclosure).

[0074] The insulating member (2) of the present disclosure exhibits non-melt moldability, thereby maintaining its insulating properties even at high temperatures. The insulating member (2) of the present disclosure can maintain good insulating properties even when the cells of an electrochemical device reach abnormally high temperatures (e.g., 400°C or higher), thereby preventing short circuits in the cells and between cell components.

[0075] In this specification, "non-melt-formable" means that the melt flow rate (MFR) is less than 0.10 g / 10 min, preferably less than 0.01 g / 10 min. The MFR is a value obtained in accordance with ASTM D1238 using a melt indexer, as the mass (g / 10 min) of polymer flowing out per 10 min from a nozzle having an inner diameter of 2.095 mm and a length of 8 mm at 372°C and a load of 5000 g (total load).

[0076] The insulating member (2) of the present disclosure may contain a resin exhibiting non-melt formability (hereinafter also referred to as a non-melt formable resin), a filler, etc. The non-melt formable resin may be a fluororesin or a non-fluororesin.

[0077] The non-melt-moldable resin has almost no fluidity at high temperatures, and therefore, in order to further improve the insulating properties, the thermal decomposition temperature is preferably 480° C. or higher, more preferably 485° C. or higher, even more preferably 490° C. or higher, even more preferably 492° C. or higher, and particularly preferably 495° C. or higher. Alternatively, the thermal decomposition temperature may be 600° C. or lower, 550° C. or lower, or 520° C. or lower. The thermal decomposition temperature is the temperature at which the mass loss of the sample reaches 1% by mass when measured using a thermogravimetric and differential thermal analyzer (STA7200 manufactured by Hitachi High-Tech Science Corporation) in an air atmosphere at a heating rate of 10°C / min.

[0078] The non-melt-moldable resin is also preferably crosslinked.

[0079] Examples of the non-melt-moldable resin include PTFE, ultra-high molecular weight polyethylene, thermosetting resins, crosslinked resins, etc., and among these, PTFE, ultra-high molecular weight polyethylene, phenolic resins, epoxy resins, melamine resins, urea resins, unsaturated polyester resins, alkyd resins, silicone resins, polyurethanes, thermosetting polyimides, and crosslinked polyethylenes are preferred, with PTFE and ultra-high molecular weight polyethylenes being more preferred.

[0080] The PTFE may be the same as the PTFE in the insulating member (1) of the present disclosure.

[0081] The ultra-high molecular weight polyethylene has a weight average molecular weight of 1.0 × 10 6 It is preferable that the value is 2.0×10 or more. 6 More preferably, it is 7.0 × 10 or more. 7 It may be less than 7.0 x 10 6 It may be the following: The molecular weight of the ultra-high molecular weight polyethylene is measured by gel permeation chromatography (GPC) in terms of polystyrene.

[0082] Examples of commonly available ultra-high molecular weight polyethylene include Tiber UHMW-PE manufactured by Mitsubishi Chemical Advanced Materials Corporation and Hi-Zex Million manufactured by Mitsui Chemicals, Inc.

[0083] The filler is preferably an insulating filler, and is not preferably a conductive filler. Examples of the filler include known insulating fillers such as aluminum oxide, silicon oxide, magnesium oxide, anhydrous magnesium carbonate, magnesium hydroxide, silicon oxide, silicon nitride, boron nitride, and aluminum nitride, with magnesium oxide, aluminum nitride, and boron nitride being preferred.

[0084] The insulating member (2) of the present disclosure may contain components other than the non-melt-formable resin, but is preferably made essentially of the non-melt-formable resin. This allows the effects of the non-melt-formable resin to be significantly exhibited. "Made essentially of the non-melt-formable resin" means that the content of the non-melt-formable resin is 70% by mass or more of the insulating member. The content of the non-melt-moldable resin relative to the insulating member is preferably 90.0% by mass or more, more preferably 95.0% by mass or more, even more preferably 99.0% by mass or more, particularly preferably 99.9% by mass or more, and most preferably 99.95% by mass or more. It is also preferable that the insulating member (2) of the present disclosure is made solely of the non-melt-moldable resin.

[0085] The insulating member (2) of the present disclosure can be produced by molding a raw material composition containing a raw material resin into a desired shape. The form of the raw material composition is not limited, and may be a powder, a dispersion liquid, or the like, but powder is preferred. The molding method is also not limited, and in addition to the molding methods exemplified for the insulating member (1) of the present disclosure, known molding methods can be used.

[0086] The insulating member of the present disclosure is a member used to provide electrical insulation in an electrochemical device. The insulating member of the present disclosure may provide insulation between two or more conductive members of an electrochemical device, for example, between a positive electrode and a negative electrode, or between an electrode and another member (for example, an exterior such as a lid).

[0087] In order to further improve the insulating properties at high temperatures, the insulating member of the present disclosure preferably has an endothermic peak temperature of 333°C or higher, more preferably 335°C or higher, even more preferably 337°C or higher, and even more preferably 340°C or higher, and preferably 350°C or lower, and more preferably 346°C or lower. The endothermic peak temperature is the temperature corresponding to the minimum point in the heat of fusion curve obtained by performing differential scanning calorimetry (DSC) at a heating rate of 10°C / min on an insulating material that has not been heated to a temperature of 300°C or higher. When there are two or more minimum points in one melting peak, each of them is considered to be the endothermic peak temperature.

[0088] In order to further improve the insulating properties at high temperatures, the insulating member of the present disclosure preferably has a melting point of 315°C or higher, more preferably 320°C or higher, even more preferably 323°C or higher, and even more preferably 325°C or higher, and preferably 335°C or lower, and more preferably 330°C or lower. The melting point is the temperature corresponding to the minimum point on the heat of fusion curve obtained by performing differential scanning calorimetry (DSC) at a heating rate of 10°C / min on an insulating material that has been heated to a temperature of 300°C or higher.

[0089] The insulating member of the present disclosure preferably has a heat of fusion of 27 J / g or more, more preferably 30 J / g or more, even more preferably 33 J / g or more, even more preferably 50 J / g or more, and particularly preferably 60 J / g or more, and may also be 90 J / g or less, or may be 80 J / g or less, in that it can delay the temperature rise when heat is generated and prevent the material from reaching an abnormally high temperature in a short period of time. The heat of fusion is a value measured using a differential scanning calorimeter (DSC).

[0090] In order to further improve the insulating properties at high temperatures, the insulating member of the present disclosure preferably has a heat of crystallization of 50 J / g or less, more preferably 40 J / g or less, even more preferably 30 J / g or less, and even more preferably 25 J / g or less, and may also be 10 J / g or more, or 15 J / g or more. The heat of crystallization is a value measured using a differential scanning calorimeter (DSC).

[0091] In order to further improve insulating properties at high temperatures, the insulating member of the present disclosure preferably has a thermal decomposition temperature of 400°C or higher, more preferably 430°C or higher, and even more preferably 450°C or higher. Alternatively, the thermal decomposition temperature may be 600°C or lower, 550°C or lower, or 520°C or lower. The thermal decomposition temperature is the temperature at which the mass loss of the sample reaches 1% by mass when measured using a thermogravimetric and differential thermal analyzer (STA7200 manufactured by Hitachi High-Tech Science Corporation) in an air atmosphere at a heating rate of 10°C / min.

[0092] The insulating member of the present disclosure has a melt viscosity of 1.0×10 at 380° C., which further improves insulating properties at high temperatures. 7 Pa·s or more is preferable, and 1.0×108 It is more preferable that the viscosity is 1.0×10 Pa·s or more. 11 Pa s or less, and 5.0 × 10 10 It may be less than Pa·s. The melt viscosity is measured using a melt viscoelasticity measuring device MCR302 (manufactured by Anton Paar Japan Co., Ltd.) using a parallel plate measuring jig with a diameter of 7 mm, and the complex viscosity measured at a deformation rate of 0.3%, a sample thickness of 0.5 mm, a temperature of 380°C, and a frequency of 0.01 radians per second is defined as the melt viscosity.

[0093] In order to further improve the insulating properties at high temperatures, the insulating member of the present disclosure preferably has a standard specific gravity (SSG) of 2.200 or less, more preferably 2.190 or less, even more preferably 2.180 or less, and even more preferably 2.175 or less, and may also be 2.130 or more, 2.140 or more, or 2.150 or more. The SSG is measured by the water displacement method according to ASTM D 792 using a sample molded according to ASTM D 4895 89.

[0094] The insulating member of the present disclosure preferably has non-melt-fabricability, which means that the melt flow rate cannot be measured at a temperature higher than the melting point in accordance with ASTM D-1238 and D-2116, in other words, the insulating member does not easily flow even in the melting temperature range.

[0095] In order to further improve insulating properties at high temperatures, the insulating member of the present disclosure preferably has an insulation resistance of 1 MΩ or more after heating at 450°C, more preferably 10 MΩ or more, and even more preferably 100 MΩ or more. The insulation resistance is measured by the method described in the examples below.

[0096] The insulating member of the present disclosure has good sealing properties even at high temperatures, and can therefore be suitably used as a sealing member. A sealing member is a member used to prevent the leakage of liquid or gas or the intrusion of liquid or gas from the outside. Examples of the sealing member include gaskets and packing, and among these, gaskets (insulating gaskets) are preferred.

[0097] The shape of the insulating member of the present disclosure is not particularly limited and may be, for example, an annular shape. Furthermore, the insulating member of the present disclosure may have a circular, oval, rectangular shape with rounded corners, or the like in a plan view, and may have a through hole in the center.

[0098] The insulating member of the present disclosure may have a cylindrical portion and a flange portion extending radially from one opening of the cylindrical portion. An insulating member having such a structure can be suitably used, for example, to insulate an external terminal having a terminal head and a shaft portion. In this embodiment, when the shaft portion of the external terminal is arranged so as to face the interior of the electrochemical device (for example, when it faces the same direction as the external terminal 2 in FIGS. 1 and 2 described below), the insulating member of the present disclosure is preferably arranged so that the opening of the cylindrical portion opposite the flange portion faces the interior of the electrochemical device. When the shaft portion of the external terminal is arranged so as to face the exterior of the electrochemical device (when it is upside down from the external terminal 2 in FIGS. 1 and 2), the insulating member of the present disclosure is preferably arranged so that the opening of the cylindrical portion opposite the flange portion faces the exterior of the electrochemical device.

[0099] A mode of use of an insulating member according to an embodiment of the present disclosure will be described with reference to the drawings.

[0100] 1, an electrochemical device 10 (for example, a sealed prismatic secondary battery) includes an outer can (not shown) and a lid 1. An electric element (not shown), such as a power generator, is housed inside the outer can, and the opening of the outer can is hermetically sealed with the lid 1. The lid 1 is provided with an external terminal 2 (positive or negative terminal), and externally generated power is supplied to an electric element via the external terminal 2 for storage, and also supplied to an external load.

[0101] In order to electrically insulate the external terminal 2 from the lid 1, an insulating member (gasket) 3 and an insulating plate 4 are provided on the lid 1. The insulating member 3 corresponds to the insulating member of the present disclosure. The external terminal 2 has a terminal head 21 having a rectangular parallelepiped block shape and a cylindrical shaft 22. The shaft 22 protrudes from the lower surface of the terminal head 21 (toward the interior of the electrochemical device).

[0102] As shown in FIG. 1, the insulating member 3 has a cylindrical portion 31, a flange portion 32 that extends radially from one opening of the cylindrical portion 31, and a sidewall portion 33 that rises from the periphery of the flange portion 32.

[0103] The cylindrical portion 31 is fitted onto the shaft portion 22 of the external terminal 2, and the inner peripheral surface of the cylindrical portion 31 abuts against the outer peripheral surface of the shaft portion 22. The cylindrical portion 31 is also inserted into the through-hole of the lid 1, and the outer peripheral surface of the cylindrical portion 31 abuts against the inner peripheral surface of the through-hole of the lid 1.

[0104] The flange portion 32 is sandwiched between the lid 1 and the external terminal 2 , with one contact surface of the flange portion 32 contacting the lower surface of the external terminal 2 and the other contact surface of the flange portion 32 contacting the surface of the lid 1 .

[0105] With the cylindrical portion 31 and flange portion 32 of the insulating member 3 compressed, the insulating member 3 comes into contact with the external terminal 2 and the lid 1, thereby ensuring the hermeticity of the electrochemical device.

[0106] The insulating member of the present disclosure can be used alone or in combination with other members. The insulating member of the present disclosure may be laminated with other members. The other members may be insulating members or sealing members.

[0107] It is preferable that the other members include a material different from the insulating member of the present disclosure, for example, a non-fluorine resin such as polyethylene (PE), polypropylene (PP), or polybutylene terephthalate (PBT), or a fluorine resin other than PTFE such as tetrafluoroethylene / perfluoro(alkyl vinyl ether) copolymer (PFA).

[0108] Specific examples of the embodiment in which the insulating member of the present disclosure is used in combination with other members are shown in FIGS.

[0109] In Figure 2, the insulating member (gasket) 3 comprises a member 3a containing PTFE and ensuring insulation at high temperatures, and a member 3b containing another material (e.g., PP) and ensuring sealing properties under normal conditions other than high temperatures. Members 3a and 3b may be in contact with each other, or may be adjacent but not in contact. Adjacent refers to a state in which the members are not in contact but are within a distance of 3 mm. Note that the same effect can be obtained by swapping the materials and functions of members 3a and 3b.

[0110] In FIG. 3, insulating member (gasket) 3 has a laminated structure of member 3c, which contains PTFE and ensures insulation at high temperatures, and member 3d, which contains another material (e.g., PP) and ensures insulation under normal conditions other than high temperatures. The members 3c and 3d may be partially overlapping. A partially overlapping state means that when comparing the members 3c and 3d, there are parts where the members 3c and 3d do not overlap for reasons such as the edges of the members not overlapping, the width or depth being different, the positions being misaligned, or there being a hole or gap. By making member 3c smaller than member 3d, material costs can be reduced. Furthermore, by making member 3c larger than member 3d, insulation properties at high temperatures can be improved. Furthermore, member 3c may have holes or gaps. In this case, material costs can be reduced. Insulation properties at high temperatures can be improved by not having holes or gaps. Furthermore, member 3c may be divided into multiple parts. In this case, assembly may be easier.

[0111] The following method can be exemplified as a method for realizing a structure in which the insulating member of the present disclosure and another member are stacked. (I) A molded article is prepared in which the insulating member of the present disclosure and other members are laminated in advance, and the molded article is attached to an electrochemical device. (II) The insulating member of the present disclosure and another member, which are separate members, are attached to and fixed in an electrochemical device, thereby forming a laminate. (III) A portion of the surface of another member is coated with a material (such as PTFE) for forming the insulating member of the present disclosure, and then the member is attached to the electrochemical device.

[0112] As a specific method for coating in the above (III), the following method can be exemplified. (i) A dispersion containing the material of the insulating member of the present disclosure (for example, a PTFE dispersion) is applied to the surface of another member, which may then be dried and then baked. (ii) A sintered tape containing the insulating member material of the present disclosure (e.g., sintered PTFE tape) is wound around the surface of another member. (iii) Wrapping a fully unsintered or unsintered tape (e.g., fully unsintered or unsintered PTFE tape) containing the insulating member material of the present disclosure around the surface of another member. (iv) A tape containing the insulating material of the present disclosure that is not completely sintered or not sintered at all (e.g., a PTFE tape that is not completely sintered or not sintered at all) is attached to the surface of another member. The attachment may be via an adhesive or glue.

[0113] The insulating member of the present disclosure is used in electrochemical devices such as batteries and capacitors. Examples of the battery include secondary batteries such as lithium ion batteries and sodium ion batteries. A sodium-ion secondary battery is a secondary battery in which sodium ions in an electrolyte solution are responsible for electrical conduction. For example, sodium metal oxides can be used as the active material for the positive electrode. Salts in the electrolyte include inorganic sodium salts such as NaPF6, NaBF4, NaClO4, and NaAsF6; and organic sodium salts such as NaCF3SO3, NaPF3(C2F5)3, NaN(CF3SO2)2, NaN(C2F5SO2)2, NaC(CF3SO2)3, and NaN(FSO2)2. Hard carbon can be used as the negative electrode material. The capacitor is not particularly limited, but is preferably an electrochemical capacitor. Examples of electrochemical capacitors include electric double layer capacitors, hybrid capacitors, and redox capacitors. Examples of hybrid capacitors include sodium ion capacitors, lithium ion capacitors, and magnesium ion capacitors. Among these, electric double layer capacitors are particularly preferred.

[0114] The insulating member of the present disclosure can be suitably used as an insulating member for batteries, and can be particularly suitably used as an insulating member for secondary batteries such as lithium ion batteries and sodium ion batteries.

[0115] The secondary battery may be a secondary battery that uses an electrolytic solution or a solid secondary battery. In this specification, the solid-state secondary battery may be a secondary battery containing a solid electrolyte, and may be a semi-solid-state secondary battery containing a solid electrolyte and a liquid component as the electrolyte, or an all-solid-state secondary battery containing only a solid electrolyte as the electrolyte.

[0116] The insulating member of the present disclosure can be used in contact with an electrolyte included in an electrochemical device, i.e., can have a contact surface with the electrolyte. Even when used in such a state, the insulating member of the present disclosure can maintain excellent insulating properties at high temperatures. The electrolyte referred to here includes not only the electrolyte itself but also substances derived from the electrolyte, and may be a liquid, solid, or gas. The gas includes, for example, a vaporized electrolytic solution or a gas generated by decomposition of the electrolytic solution during charging and discharging.

[0117] The electrochemical device according to the present disclosure preferably includes a nonaqueous electrolyte. The insulating member according to the present disclosure may be used in contact with the nonaqueous electrolyte included in the electrochemical device, i.e., may have a liquid-contact surface with the nonaqueous electrolyte included in the electrochemical device.

[0118] The non-aqueous electrolyte may be prepared by dissolving a known electrolyte salt in a known organic solvent for dissolving electrolyte salts.

[0119] The organic solvent for dissolving the electrolyte salt is not particularly limited, and one or more of known hydrocarbon solvents such as propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyrolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; and fluorine-containing solvents such as fluoroethylene carbonate, fluoroethers, and fluorinated carbonates can be used.

[0120] Examples of electrolyte salts include LiClO4, LiAsF6, LiBF4, LiPF6, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiCl, LiBr, CH3SO3Li, CF3SO3Li, and cesium carbonate. In view of good cycle characteristics, LiPF6, LiBF4, LiN(SO2CF3)2, LiN(SO2C2F5)2, or combinations thereof are particularly preferred.

[0121] The concentration of the electrolyte salt is preferably 0.8 mol / L or more, more preferably 1.0 mol / L or more. The upper limit is usually 1.5 mol / L, although it depends on the organic solvent used to dissolve the electrolyte salt.

[0122] The solid electrolyte used in the solid secondary battery may be a sulfide-based solid electrolyte or an oxide-based solid electrolyte. In particular, when a sulfide-based solid electrolyte is used, there is an advantage in that the flexibility of the sheet is improved.

[0123] The sulfide-based solid electrolyte is not particularly limited and may be Li2S-P2S5, Li2S-P2S3, Li2S-P2S3-P2S5, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, LiI-Li2S-SiS2-P2S5, Li2S-SiS2-Li4SiO4, Li2S-SiS2-Li3PO4, Li3PS4-Li4GeS4, Li 3.4 P 0.6 Si 0.4 S4, Li 3.25 P 0.25 Ge 0.76 S4, Li 4-x Ge 1-x P x S4(x=0.6~0.8), Li 4+y Ge 1-y Ga y S4(y=0.2~0.3), LiPSCl, LiCl, Li 7-x-2y PS 6-x-y Cl x (0.8≦x≦1.7, 0 <y≦-0.25x+0.5)、Li 10 SnP2S 12 Any one selected from the above, or a mixture of two or more thereof, can be used.

[0124] The sulfide-based solid electrolyte preferably contains lithium. Sulfide-based solid electrolytes containing lithium are used in solid-state batteries that use lithium ions as a carrier, and are particularly preferred in terms of electrochemical devices having high energy density.

[0125] The oxide-based solid electrolyte is preferably a compound that contains oxygen atoms (O), has the ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, and has electronic insulation properties.

[0126] Specific examples of compounds include Li xa La ya TiO3 [xa=0.3~0.7, ya=0.3~0.7] (LLT), Li xb La yb Zr zb M bb mb O nb (M bb is at least one element selected from Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In, and Sn, where xb satisfies 5≦xb≦10, yb satisfies 1≦yb≦4, zb satisfies 1≦zb≦4, mb satisfies 0≦mb≦2, and nb satisfies 5≦nb≦20.), Li xc B yc M cc zc O nc (M cc is at least one element selected from C, S, Al, Si, Ga, Ge, In, and Sn, where xc satisfies 0≦xc≦5, yc satisfies 0≦yc≦1, zc satisfies 0≦zc≦1, and nc satisfies 0≦nc≦6.), Li xd (Al,Ga) yd (Ti,Ge) zd Si ad P md O nd (where 1≦xd≦3, 0≦yd≦2, 0≦zd≦2, 0≦ad≦2, 1≦md≦7, 3≦nd≦15), Li (3-2xe) M ee xe D ee O(xe represents a number between 0 and 0.1, and M ee represents a divalent metal atom. ee represents a halogen atom or a combination of two or more halogen atoms.) Li xf Si yf O zf (1≦xf≦5, 0 <yf≦3、1≦zf≦10)、Li xg S yg O zg (1≦xg≦3, 0 <yg≦2、1≦zg≦10)、Li3BO3-Li2SO4、Li2O-B2O3-P2O5、Li2O-SiO2、Li6BaLa2Ta2O 12 , LiPO(4-3 / 2w) N w (w<1), Li with LISICON (Lithium super ionic conductor) type crystal structure 3.5 Zn 0.25 GeO4, La with perovskite crystal structure 0.51 Li 0.34 TiO 2.94 , La 0.55 Li 0.35 TiO3, LiTi2P3O with NASICON (sodium super ionic conductor) type crystal structure 12 , Li 1+xh+yh (Al,Ga) xh (Ti,Ge) 2-xh Si yh P 3-yh O 12 (where 0≦xh≦1, 0≦yh≦1), Li7La3Zr2O with a garnet-type crystal structure 12 (LLZ), etc. Ceramic materials in which elements are substituted for LLZ are also known. For example, Li 6.24 La3Zr2Al 0.24 O 11.98 , Li 6.25 Al 0.25 La3Zr2O 12 and Ta-substituted Li 6.6 La3Zr 1.6 Ta 0.4 O 12 , Nb-substituted Li 6.75 La3Zr 1.75 Nb 0.25 O 12 Other examples include LLZ-based ceramic materials in which at least one element, Mg (magnesium) or A (A is at least one element selected from the group consisting of Ca (calcium), Sr (strontium), and Ba (barium)), is substituted for LLZ. Phosphorus compounds containing Li, P, and O are also desirable. For example, lithium phosphate (Li3PO4), LiPON, LiPOD, and other lithium phosphates in which some of the oxygen in the lithium phosphate is substituted with nitrogen, are also desirable. 1 (D 1is at least one selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, Au, etc. 1 ON(A 1 is at least one selected from Si, B, Ge, Al, C, Ga, etc. Specific examples include Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2 and Li2O-Al2O3-SiO2-P2O5-TiO2.

[0127] The oxide-based solid electrolyte preferably contains lithium. The oxide-based solid electrolyte containing lithium is used in a solid-state battery that uses lithium ions as a carrier, and is particularly preferred in terms of electrochemical devices having a high energy density.

[0128] The oxide-based solid electrolyte is preferably an oxide having a crystalline structure. Oxides having a crystalline structure are particularly preferred in terms of good Li-ion conductivity. Examples of oxides having a crystalline structure include perovskite-type (La 0.51 Li 0.34 TiO 2.94 etc.), NASICON type (Li 1.3 Al 0.3 Ti 1.7 (PO4)3, etc.), garnet type (Li7La3Zr2O 12 (LLZ), etc. Among these, garnet type is preferred.

[0129] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims. [Example]

[0130] The present disclosure will now be described in more detail with reference to examples, but the present disclosure is not limited to these examples.

[0131] Various physical properties were measured by the following methods.

[0132] <Modified Monomer Content> The PPVE content in PTFE was determined by press-molding a sample to produce a thin film disk, and measuring the infrared absorbance of the thin film disk with FT-IR. -1 Absorbance at / 935cm -1 The absorbance ratio was calculated by multiplying the absorbance ratio by 0.14. The PPVE content in the PFA was measured using an NMR analyzer (for example, AVANCE300 high temperature probe manufactured by Bruker Biospin).

[0133] <Standard specific gravity (SSG)> Using samples molded in accordance with ASTM D4895 89, measurements were made by the water displacement method in accordance with ASTM D 792.

[0134] <Heat of fusion> The resulting sheet was cut, and approximately 3 mg was weighed and placed in a dedicated aluminum pan. Using an X-DSC7000 (Hitachi High-Tech Science Corporation), the temperature was raised to the melting peak temperature +40°C at a rate of 10°C / min under a nitrogen atmosphere, and the heat of fusion was measured. The heat of fusion was calculated by drawing a line from the melting peak temperature -40°C to the melting peak temperature +20°C on the resulting DSC chart. The area enclosed by the line and the curve containing the peak was then calculated.

[0135] <Heat of crystallization> The resulting sheet was cut, and approximately 3 mg was weighed and placed in a dedicated aluminum pan. Using an X-DSC7000 (Hitachi High-Tech Science Corporation), the temperature was raised to +40°C (crystallization peak temperature) at a rate of 10°C / min under a nitrogen atmosphere, held for 1 minute, and then lowered to -60°C (crystallization peak temperature) at a rate of 10°C / min to measure the heat of crystallization at the crystallization point. The heat of crystallization was determined by drawing a line from -30°C (crystallization peak temperature) to +25°C (crystallization peak temperature) on the resulting DSC chart and determining the area enclosed by the line and the curve containing the peak.

[0136] <Melt viscosity> Quantification was performed using a melt viscoelasticity measuring device MCR302 (manufactured by Anton Paar Japan Co., Ltd.). A parallel plate with a diameter of 7 mm was used as the measurement jig, and the complex viscosity measured at a deformation rate of 0.3%, a sample thickness of 0.5 mm, a temperature of 380°C, and a frequency of 0.01 radians per second was taken as the melt viscosity. If the viscosity is too low or if the sample polymer gasifies due to thermal decomposition, the viscosity should be set to 100 Pa·s or less.

[0137] <Melt moldability (MFR)> According to ASTM D1238, a melt indexer was used to measure the mass of polymer (g / 10 min) flowing per 10 minutes from a nozzle with an inner diameter of 2.095 mm and a length of 8 mm at 372°C and a load of 5000 g (total load). An MFR of 0.10 g / 10 min or greater was deemed to be melt-moldable, while one less than 0.10 g / 10 min was deemed to be non-melt-moldable. Note that if the fluidity was too low to measure the MFR, it was deemed to be less than 0.10 g / 10 min. If the fluidity was too high or the polymer sample gasified due to thermal decomposition, the MFR was deemed to be 100 g / 10 min or greater.

[0138] <Insulation resistance> Using the obtained sheet, a test piece 11 (a = 3.5 mm, b = 0.2 mm, c = d = 30 mm in Figure 4(a)) was made, which had a φ3.5 mm hole in the center of a square sheet of 30 mm × 30 mm × 0.2 mm thickness, as shown in Figure 4(a). As shown in Figure 4(b), the test piece 11 and the washer 12 (e = 6.5 mm, f = 18 mm, g = 1 mm in Figure 4(b)) were stacked and fixed so that the centers of the holes in the test piece 11 and the washer 12 were aligned. As shown in Figure 5(a), the hole in the test piece 11 was enlarged using a taper punch 13 (h = 1 mm, i = 8 mm, j = 40 mm in Figure 5(a)), and a cylindrical sleeve portion was formed whose outer surface abutted against the inner surface of the hole in the washer 12. As shown in FIG. 5(b), the shank of a pin 14 (k=6 mm, l=12 mm, m=6 mm, n=8 mm in FIG. 5(b)) having a disk-shaped base and a cylindrical shank was inserted into the sleeve portion to obtain a test assembly 100 shown in FIG. 6. As shown in FIG. 7(a), a tubular jig 101 was placed over the washer 12 of the test assembly 100, and the test assembly 100 was placed in an electric furnace with a load of 5 kg applied via the tubular jig 101 in the direction of the arrow shown in FIG. 7(b). The specimen was heated in an electric furnace to an initial temperature of 250°C, and then heated to a holding temperature of 450°C at a heating rate of 10°C / min. Heat treatment was performed at the holding temperature for 10 minutes, and then the specimen was cooled to room temperature. After cooling, the load was removed, and the resistance between the washer 12 and the pin 14 was measured using an insulation measuring device (Digital Megaohm Tester 3454, manufactured by Hioki E.E. Corporation) at an applied voltage of 250V. If the insulation resistance was more than 100 MΩ, it was judged that there was insulation after heating at 450°C, and if it was less than 10 Ω, it was judged that there was no insulation after heating at 450°C. The insulation was also evaluated in the same manner when the holding temperature was set to 350° C. If the insulation resistance was over 100 MΩ, it was determined that there was insulation after heating at 350° C., and if it was less than 10 Ω, it was determined that there was no insulation after heating at 350° C.

[0139] <Water vapor permeability test> As shown in Fig. 8, 2 g of water 42 was placed in an aluminum alloy cup 41. A gasket 47 was placed between the cup 41 and a gasket compression jig 43, and a lid 44 was fastened with bolts 45 to compress the gasket 47. A spacer 46 was placed between the lid 44 and the cup 41, and the compression rate of the gasket 47 was adjusted to 37.5% or 58%. The compression ratio was calculated using the following formula. (Gasket compression rate (%)) = {1 - (distance of the gap (gasket placement portion) between the cup 41 and the gasket compression jig 43) / (height of the gasket before compression)} × 100 The mass of the permeation test jig 40 thus obtained was measured. The permeation test jig 40 was placed in an electric furnace at 80°C, left for 1000 hours, removed, and left at room temperature for 2 hours, after which the mass was measured. The water vapor permeability coefficient was calculated using the following formula. This operation was repeated three times, and the average value of the water vapor permeability coefficient was calculated. The average value is shown in Table 2. Water vapor permeability coefficient (g / 1000hr) = (mass of permeation test jig before heating) - (mass of permeation test jig after heating)

[0140] Example 1 PTFE powder (TFE homopolymer obtained by suspension polymerization, SSG = 2.159) was compression molded under a pressure of 30 MPa and held for 5 minutes. The temperature was raised to 365°C at a rate of 50°C / min in an electric furnace, and heat-treated at 365°C for 5.5 hours. The molded product was then cooled to room temperature to obtain a molded product with a diameter of 50 mm. The molded product was then machined to obtain PTFE Sheet A with a thickness of 0.2 mm. PTFE Sheet A exhibited non-melt moldability. Various physical properties were measured by the above-mentioned methods using PTFE sheet A. The results are shown in Table 1. From the obtained φ50 mm molded body, a circular gasket A with a square cross section, an inner diameter of φ14.3 mm, an outer diameter of φ17.7 mm, and a height of 1.6 mm was obtained. Gasket A showed no melt processability. A water vapor permeation test was carried out using gasket A to measure the water vapor permeation coefficient. The results are shown in Table 2.

[0141] Example 2 PTFE powder (TFE homopolymer obtained by emulsion polymerization, SSG = 2.172) was mixed with a lubricant (trade name: Isopar G (registered trademark), manufactured by Exxon), and the mixture was paste-extruded using a sheet-shaped extrusion die and heat-treated at 230°C for 30 minutes to remove the lubricant, yielding PTFE sheet B with a thickness of 0.2 mm. PTFE sheet B exhibited non-melt moldability. Various physical properties were measured by the above-mentioned methods using PTFE sheet B. The results are shown in Table 1. Similarly, the PTFE powder was mixed with a lubricant, and the mixture was paste-extruded using an RR100 mold specified in ASTM D4895. The lubricant was removed by heat treatment at 30°C for 30 minutes to obtain a PTFE round bar E having a diameter of approximately 2.5 mm. The PTFE round bar exhibited non-melt moldability. The PTFE round bar was bent into a circle to give an inner diameter of 16 mm, with 3 mm of the ends of the strand overlapping to form a gasket, to obtain Gasket B. Gasket B exhibited non-melt processability. A water vapor permeation test was carried out using gasket B to measure the water vapor permeation coefficient. The results are shown in Table 2.

[0142] Example 3 A 0.2 mm-thick PTFE sheet C was obtained in the same manner as in Example 1, except that a PTFE powder (PPVE-modified PTFE obtained by suspension polymerization (TFE / PPVE=99.89 / 0.11% by mass), SSG=2.175) was used instead of the PTFE powder in Example 1. The PTFE sheet C exhibited non-melt moldability. Various physical properties were measured by the above-mentioned methods using PTFE sheet C. The results are shown in Table 1.

[0143] Comparative Example 1 PFA pellets (TFE / PPVE = 96.1 / 3.9 mass%, MFR = 15.3 g / 10 min) were melted at 370 °C for 20 minutes using a hot plate press, and then water-cooled under a pressure of 1 MPa to obtain a 0.2 mm thick PFA sheet. The PFA sheet exhibited melt moldability. The PFA sheet was used to measure various physical properties using the methods described above. The results are shown in Table 1.

[0144] Comparative Example 2 A PTFE sheet D having a thickness of 0.2 mm was obtained in the same manner as in Comparative Example 1, except that PTFE powder (TFE homopolymer, MFR=22 g / 10 min) was used instead of the PFA pellets in Comparative Example 1. The PTFE sheet D exhibited melt moldability. Various physical properties were measured by the above-mentioned methods using PTFE sheet D. The results are shown in Table 1.

[0145] Comparative Example 3 A 0.2 mm thick PP sheet was produced in the same manner as in Comparative Example 1, except that polypropylene (PP) (product name: Prime Polypro F227, manufactured by Prime Polymer Co., Ltd.) was used instead of the PFA pellets used in Comparative Example 1, and the hot plate press temperature was 280°C instead of 370°C. The PP sheet was used to measure various physical properties using the methods described above. The results are shown in Table 1. Similarly, PP was heated to above its melting point to form a sheet, from which a circular gasket C with a square cross section measuring an inner diameter of 14.3 mm, an outer diameter of 17.7 mm, and a height of 1.6 mm was obtained. A water vapor permeation test was carried out using gasket C to measure the water vapor permeation coefficient. The results are shown in Table 2.

[0146] Comparative Example 4 A 0.2 mm thick PBT sheet was prepared in the same manner as in Comparative Example 1, except that polybutylene terephthalate (PBT) (product name: PBT Natural Color Unfilled, manufactured by Kureha Extron Co., Ltd.) was used instead of the PFA pellets used in Comparative Example 1, and the hot plate press temperature was changed to 280°C instead of 370°C. The PBT sheet was used to measure various physical properties using the methods described above. The results are shown in Table 1. Similarly, PBT was heated above its melting point to form a sheet, from which a circular gasket D with a square cross section and an inner diameter of 14.3 mm, an outer diameter of 17.7 mm, and a height of 1.6 mm was obtained. A water vapor permeation test was carried out using gasket D to measure the water vapor permeation coefficient. The results are shown in Table 2.

[0147] [Table 1] [Table 2]

[0148] The PTFE sheets (PTFE compositions) produced in the examples were suitable for use as insulating members for electrochemical devices. [Explanation of symbols]

[0149] 10: Electrochemical devices 1: Lid 2: External terminal 21: Terminal head 22: Shaft 3: Insulating material (gasket) 31: Cylindrical part 32: Flange part 33: Side wall 4: Insulating plate 11: Test piece 12: Washer 13: Tapered punch 14: Pin 100: Test assembly 101: Tubular jig 40: Transmission test fixture 41: Cup 42:Water 43: Gasket compression jig 44: Lid 45: Bolt 46: Spacer 47: Gasket

Claims

1. The polytetrafluoroethylene composition contains polytetrafluoroethylene, which is a homopolymer of tetrafluoroethylene or a modified polytetrafluoroethylene containing tetrafluoroethylene units and 1.0 mass % or less of a modifying monomer unit, The polytetrafluoroethylene composition exhibits non-melt moldability, The insulating member for electrochemical devices has a polytetrafluoroethylene content of 70 mass % or more relative to the polytetrafluoroethylene composition.

2. 2. The insulating member according to claim 1, wherein the polytetrafluoroethylene composition has a heat of crystallization of 50 J / g or less.

3. 3. The insulating member according to claim 1, wherein the polytetrafluoroethylene is a modified polytetrafluoroethylene.

4. 3. The insulating member according to claim 1, wherein the modified monomer is perfluoro(propyl vinyl ether).

5. The insulating member according to claim 1 or 2, wherein the electrochemical device comprises a non-aqueous electrolyte.

6. 3. The insulating member according to claim 1, which is a gasket.

7. 3. The insulating member according to claim 1, wherein the content of the modified monomer unit in the modified polytetrafluoroethylene is 0.20% by mass or less based on the total polymer units.

8. The content of the polytetrafluoroethylene is 99.0% by mass or more relative to the polytetrafluoroethylene composition, 8. The insulating member according to claim 7, wherein the content of the polytetrafluoroethylene composition is 99.0 mass % or more based on the insulating member.

9. 9. The insulating member according to claim 8, having a melt flow rate of less than 0.10 g / 10 min.

10. An insulating component for an electrochemical device that exhibits non-melt formability, comprising at least one non-melt formable resin selected from the group consisting of polytetrafluoroethylene and ultra-high molecular weight polyethylene, and the content of said non-melt formable resin is 70 mass% or more.

11. a melt flow rate of less than 0.10 g / 10 min; 11. The insulating member of claim 10, comprising polytetrafluoroethylene.

12. 12. The insulating member according to claim 1, 2, 10 or 11, wherein the electrochemical device is a lithium ion battery or a sodium ion battery.

13. 12. The insulating member according to claim 1, 2, 10 or 11, having a heat of fusion of 50 J / g or more.

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