Insulating member for electrochemical device

Abstract

Provided is an insulating member for an electrochemical device, said insulating member being capable of maintaining insulating properties even at high temperatures. An insulating member for an electrochemical device, which contains a polytetrafluoroethylene composition that contains polytetrafluoroethylene that is either a homopolymer of tetrafluoroethylene or a modified polytetrafluoroethylene that contains a tetrafluoroethylene unit and 1.0 mass% or less of a modifying monomer unit.

Description

Technical Field

[0001] This disclosure relates to insulating components for electrochemical devices. Background Technology

[0002] Resins such as perfluoroalkoxyalkane (PFA) are known to be used as insulating and sealing components for electrochemical devices such as lithium-ion secondary batteries (see, for example, Patent Documents 1-3).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2017-174732

[0006] Patent Document 2: International Publication No. 2020 / 066050

[0007] Patent Document 3: International Publication No. 2014 / 049645 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] The purpose of this disclosure is to provide an insulating component for an electrochemical device that can maintain insulation even at high temperatures.

[0010] Methods for solving problems

[0011] This disclosure (1) is an insulating component for an electrochemical device comprising a polytetrafluoroethylene composition comprising polytetrafluoroethylene, wherein the polytetrafluoroethylene is a homopolymer of tetrafluoroethylene or a modified polytetrafluoroethylene comprising tetrafluoroethylene units and less than 1.0% by mass of modified monomer units.

[0012] This disclosure (2) relates to the insulating component described in this disclosure (1), wherein the heat of crystallization of the polytetrafluoroethylene composition is less than 50 J / g.

[0013] This disclosure (3) relates to the insulating component described in disclosure (1) or (2), wherein the polytetrafluoroethylene composition exhibits non-melt-forming properties.

[0014] This disclosure (4) relates to an insulating member in any combination with any of the present disclosures (1) to (3), wherein the polytetrafluoroethylene is the modified polytetrafluoroethylene.

[0015] This disclosure (5) relates to an insulating component in any combination with any of the present disclosures (1) to (4), wherein the modified monomer is a perfluoro(propyl vinyl ether).

[0016] This disclosure (6) relates to an insulating component in any combination with any of the present disclosures (1) to (5), wherein the electrochemical device comprises a non-aqueous electrolyte.

[0017] This disclosure (7) relates to an insulating member, which is a gasket, in any combination with any of the disclosures (1) to (6).

[0018] This disclosure (8) relates to an insulating component in any combination with any of the present disclosures (1) to (7), wherein the content of the modified monomer unit of the modified polytetrafluoroethylene is less than 0.20% by mass relative to all polymer units.

[0019] This disclosure (9) relates to the insulating component described in this disclosure (8), wherein the content of the polytetrafluoroethylene is 99.0% by mass or more relative to the polytetrafluoroethylene composition, and the content of the polytetrafluoroethylene composition is 99.0% by mass or more relative to the insulating component.

[0020] This disclosure (10) relates to the insulating component described in this disclosure (9), having a melt flow rate of less than 0.10 g / 10 min.

[0021] This disclosure (11) is an insulating component for an electrochemical device, which exhibits non-melt-forming properties.

[0022] This disclosure (12) relates to the insulating component described in this disclosure (11) having a melt flow rate of less than 0.10 g / 10 min, the insulating component comprising polytetrafluoroethylene.

[0023] This disclosure (13) relates to an insulating component 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.

[0024] This disclosure (14) relates to an insulating component in any combination with any of the claims (1) to (13) of this disclosure, having a heat of fusion of 50 J / g or more.

[0025] Invention Effects

[0026] According to this disclosure, it is possible to provide insulating components for electrochemical devices that can maintain insulation even at high temperatures. Attached Figure Description

[0027] Figure 1 This is a schematic cross-sectional view showing an example of the structure of a portion of an electrochemical device that includes an insulating member (gasket).

[0028] Figure 2 This is a schematic cross-sectional view showing an example of the structure of a portion of an electrochemical device that includes an insulating member (gasket).

[0029] Figure 3This is a schematic cross-sectional view showing an example of the structure of a portion of an electrochemical device that includes an insulating member (gasket).

[0030] Figure 4 This diagram schematically illustrates the fabrication steps of the test assembly used in insulation resistance measurement.

[0031] Figure 5 This diagram schematically illustrates the fabrication steps of the test assembly used in insulation resistance measurement.

[0032] Figure 6 This is a schematic diagram of the test assembly used in insulation resistance measurement.

[0033] Figure 7 This is a diagram schematically illustrating one step in the insulation resistance measurement process.

[0034] Figure 8 This is a schematic diagram of the permeation test fixture used in the water vapor permeation test. Detailed Implementation

[0035] The following details this disclosure.

[0036] This disclosure provides an insulating component for electrochemical devices (hereinafter also referred to as the insulating component (1) of this disclosure) comprising a PTFE composition comprising PTFE, wherein the PTFE is a homopolymer of tetrafluoroethylene (TFE) or a modified polytetrafluoroethylene (PTFE) comprising TFE units and less than 1.0% by mass of modified monomer units.

[0037] It should be noted that, unless otherwise specified, the insulating component (1) of this disclosure and the insulating component (2) of this disclosure described later are collectively referred to as "the insulating component of this disclosure".

[0038] The insulating component (1) disclosed herein maintains its insulation properties even at high temperatures by comprising a specific PTFE composition.

[0039] In electrochemical devices requiring large output, such as lithium-ion batteries for power applications, multiple battery cells are typically configured in parallel or series connection in close proximity. In such a configuration, even if the battery cells reach abnormally high temperatures (e.g., above 400°C) due to a fire in one of the adjacent battery cells, the insulating component (1) of this disclosure can maintain good insulation and prevent short circuits between battery cells and between components of the battery cells.

[0040] The PTFE in the insulating component (1) of this disclosure is a homopolymer of TFE or modified PTFE. Modified PTFE is preferred from the perspective of superior insulation at high temperatures and excellent low water vapor permeability.

[0041] The modified PTFE described above comprises TFE units and less than 1.0% by mass of modified monomer units. The amount of TFE units can be 99.0% by mass or more. Alternatively, the modified PTFE described above can be composed solely of TFE units and modified monomer units.

[0042] In the aforementioned modified PTFE, from the perspective of further improving insulation performance at high temperatures and reducing water vapor permeability, the content of the modified monomer unit relative to all polymer units is preferably in the range of 0.00001 to 1.0% by mass. As a lower limit for the content of the modified monomer unit, 0.0001% by mass is more preferred, 0.001% by mass is even more preferred, 0.005% by mass is even more preferred, and 0.010% by mass is particularly preferred. As an upper limit for the content of the modified monomer unit, 0.90% by mass is preferred, 0.80% by mass is more preferred, 0.50% by mass is even more preferred, 0.40% by mass is even more preferred, 0.30% by mass is even more preferred, 0.20% by mass is even more preferred, and 0.10% by mass is particularly preferred.

[0043] In this specification, the modified monomer unit refers to a portion of the molecular structure of PTFE that is derived from the modified monomer.

[0044] The content of each of the above-mentioned polymerization units can be calculated by appropriately combining NMR, FT-IR, elemental analysis, and fluorescence X-ray analysis according to the type of monomer.

[0045] As for the aforementioned modified monomers, there are no particular limitations as long as they can copolymerize with TFE. Examples include perfluoroolefins such as hexafluoropropylene [HFP]; hydrofluoroolefins such as trifluoroethylene and vinylidene fluoride [VDF]; perhaloolefins such as chlorotrifluoroethylene [CTFE]; perfluorovinyl ethers; perfluoroallyl ethers; (perfluoroalkyl)ethylene; and ethylene. Furthermore, one or more modified monomers can be used.

[0046] The perfluorovinyl ethers mentioned above are not particularly limited; for example, perfluorounsaturated compounds represented by the following general formula (A) can be cited.

[0047] (where Rf) 1 (This refers to a perfluorinated organic group). In this specification, "perfluorinated organic group" means an organic group in which all hydrogen atoms bonded to carbon atoms are replaced by fluorine atoms. The perfluorinated organic group may have an ether oxygen atom.

[0048] Examples of perfluorovinyl ethers include, for instance, Rf in general formula (A). 1The perfluoroalkyl group is a perfluoro(alkyl vinyl ether) [PAVE] with 1 to 10 carbon atoms. The preferred number of carbon atoms in the perfluoroalkyl group is 1 to 5.

[0049] Examples of perfluoroalkyl groups in the aforementioned PAVE include perfluoromethyl, perfluoroethyl, perfluoropropyl, perfluorobutyl, perfluoropentyl, and perfluorohexyl.

[0050] As a further example of the aforementioned perfluorovinyl ether, in the above general formula (A), Rf 1 Substances with a perfluoro(alkoxyalkyl) group having 4 to 9 carbon atoms; Rf 1 Substances with groups represented by the following formula,

Chemistry 1

[0051] (In the formula, m represents 0 or an integer from 1 to 4); Rf 1 Substances containing groups represented by the following formulas,

Chemistry 2

[0052] (In the formula, n represents an integer from 1 to 4).

[0053] There is no particular limitation as to (perfluoroalkyl)ethylene [PFAE], for example, (perfluorobutyl)ethylene [PFBE], (perfluorohexyl)ethylene, etc.

[0054] Examples of hydrofluoric alkenes include CH2=CF2, CFH=CH2, CFH=CF2, CH2=CFCF3, CH2=CHCF3, CHF=CHCF3 (E-form), and CHF=CHCF3 (Z-form).

[0055] Examples of perfluoroallyl ethers include, for example, fluorinated monomers represented by general formula (B).

[0056] (where Rf) 2 (Indicates a perfluorinated organic group).

[0057] The above Rf 2Preferred are perfluoroalkyl groups having 1 to 10 carbon atoms or perfluoroalkoxyalkyl groups having 1 to 10 carbon atoms. As the above-mentioned perfluoroallyl ether, it is preferably selected from at least one of 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 from at least one of the group consisting of CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9, and even more preferably from CF2=CF-CF2-O-CF2CF2CF3.

[0058] As the modified monomers mentioned above, from the perspective of further improving insulation at high temperatures and low water vapor permeability, it is preferable to select at least one of the group consisting of PAVE, PFAE, HFP and CTFE, more preferably at least one of the group consisting of PAVE and HFP, further preferably PAVE, and even more preferably perfluoro(propyl vinyl ether) [PPVE].

[0059] The aforementioned PTFE can have a core-shell structure. Examples of PTFEs with a core-shell structure include modified PTFE, which contains a core of high molecular weight PTFE and a shell of lower molecular weight PTFE or modified PTFE within the particles. Examples of such modified PTFEs include the PTFE described in Japanese Patent Application Publication No. 2005-527652.

[0060] The PTFE mentioned above can be obtained by emulsion polymerization or by suspension polymerization. From the perspective of improving low water vapor permeability, PTFE obtained by emulsion polymerization is preferred, and PTFE obtained by emulsion polymerization without firing (without being heated to a temperature above the melting point) is more preferred.

[0061] From the perspective of further improving the insulation performance at high temperatures, the endothermic peak temperature of the above-mentioned PTFE composition is preferably 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. In addition, it is preferably 350°C or lower, and more preferably 346°C or lower.

[0062] Regarding the aforementioned endothermic peak temperatures, for PTFE compositions that have not been heated to temperatures above 300°C, differential scanning calorimetry (DSC) was performed at a heating rate of 10°C / min, and the temperature corresponding to the minimum point in the obtained heat of fusion curve was determined. In cases where there are two or more minimum points within a single melting peak, each was used as the endothermic peak temperature.

[0063] From the perspective of further improving the insulation performance at high temperatures, the melting point of the above-mentioned PTFE composition is preferably 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. In addition, it is preferably 335°C or lower, and more preferably 330°C or lower.

[0064] Regarding the above melting point, differential scanning calorimetry (DSC) was performed on PTFE compositions that had been heated to temperatures above 300°C at a heating rate of 10°C / min, and the temperature corresponds to the minimum point in the obtained heat of fusion curve.

[0065] The PTFE composition described above can be an incompletely fired PTFE composition. Incompletely fired PTFE compositions have a high heat of fusion and sometimes take time to fully melt, thus having the advantage of being able to delay the temperature rise during heating and preventing abnormally high temperatures from being reached in a short time.

[0066] From the perspective of being able to delay the temperature rise when heating and preventing abnormally high temperatures from being reached in a short period of time, the heat of fusion of the above-mentioned PTFE composition is preferably 27 J / g or more, more preferably 30 J / g or more, even more preferably 33 J / g or more, particularly preferably 60 J / g or more, and can also be 90 J / g or less, or 80 J / g or less.

[0067] The heat of fusion mentioned above is a value measured using a differential scanning calorimeter (DSC).

[0068] From the perspective of further improving the insulation performance at high temperatures, the heat of crystallization of the above-mentioned PTFE composition is preferably 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. Alternatively, it can be 10 J / g or more, or 15 J / g or more.

[0069] The above-mentioned heat of crystallization is a value determined using a differential scanning calorimeter (DSC).

[0070] From the perspective of further improving the insulation performance at high temperatures, the thermal decomposition temperature of the above-mentioned PTFE composition is preferably 400°C or higher, more preferably 430°C or higher, and even more preferably 450°C or higher. Alternatively, it can be 600°C or lower, 550°C or lower, or 520°C or lower.

[0071] The above-mentioned thermal decomposition temperature is the temperature at which the mass reduction rate of the sample reaches 1% by mass under the conditions of air atmosphere and a heating rate of 10°C / min, using a differential thermal and thermogravimetric analysis apparatus (Hitachi High-Tech Science STA7200).

[0072] From the perspective of further improving insulation performance at high temperatures, the melt viscosity of the above-mentioned PTFE composition at 380°C is preferably 1.0 × 10⁻⁶. 7 Pa·s or higher, more preferably 1.0 × 10⁻⁶ Pa·s or higher. 8 Pa·s or higher. Alternatively, it can be 1.0 × 10⁻⁶ Pa·s or higher. 11 For values ​​below Pa·s, it can also be 5.0 × 10⁻⁶. 10 Pa·s and below.

[0073] The melt viscosity was quantified using a melt viscoelasticity measuring device MCR302 (manufactured by Anton Paar Japan Co., Ltd.). The measuring fixture used a parallel plate 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 was taken as the melt viscosity.

[0074] From the perspective of further improving the insulation performance at high temperatures, the standard specific gravity (SSG) of the above-mentioned PTFE composition is preferably 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. Alternatively, it can be 2.130 or more, 2.140 or more, or 2.150 or more.

[0075] The above SSG was measured using samples molded according to ASTM D 4895 89 and determined by the water displacement method according to ASTM D 792.

[0076] The PTFE composition described above preferably exhibits non-melting secondary processability. This non-melting secondary processability refers to the property, according to ASTM D-1238 and D-2116, that the melt flow rate cannot be determined at temperatures above the melting point; in other words, it does not flow easily even in the melting temperature range.

[0077] The above-described PTFE composition preferably exhibits non-melt-forming properties. These non-melt-forming properties will be described later.

[0078] The PTFE composition described above can be a calcined PTFE composition or an uncalcined PTFE composition. Additionally, it can be a PTFE composition that has been heated to a temperature above its melting point or a PTFE composition that has not been heated to a temperature above its melting point.

[0079] PTFE compositions that have not been heated above their melting point have the property of easily stretching and becoming soft when processed into green strips. Therefore, they have the following advantages: they can easily follow the shape of the component when wound, can easily attach to components with simple shapes as well as complex shapes, and can provide insulation to the periphery of the component.

[0080] The PTFE composition described above may contain components other than PTFE, and preferably consists substantially only of PTFE. This allows the effects of PTFE to be significantly exerted. "Substantially consisting only of PTFE" means that the PTFE content relative to the PTFE composition is 70% by mass or more.

[0081] The content of PTFE relative to 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.

[0082] The above-mentioned PTFE composition is preferably composed of only the above-mentioned PTFE.

[0083] The PTFE composition described above may contain fillers, etc. As fillers, insulating fillers are preferred, while conductive fillers are not preferred. Examples of known insulating fillers include alumina, silicon oxide, magnesium oxide, anhydrous magnesium carbonate, magnesium hydroxide, silicon oxide, silicon nitride, boron nitride, and aluminum nitride; magnesium oxide, aluminum nitride, and boron nitride are preferred.

[0084] The insulating component (1) of this disclosure may contain components other than the PTFE composition described above, but preferably is substantially composed only of the PTFE composition described above. Therefore, the effects of the PTFE composition described above can be significantly utilized. "Substantially composed only of the PTFE composition" means that the content of the PTFE composition is 70% by mass or more relative to the insulating component described above.

[0085] The content of the above-mentioned PTFE composition relative to the above-mentioned insulating component is preferably 90.0% by mass or more, more preferably 95.0% by mass or more, further preferably 99.0% by mass or more, particularly preferably 99.9% by mass or more, and most preferably 99.95% by mass or more.

[0086] The insulating component (1) disclosed herein is preferably composed solely of the aforementioned PTFE composition.

[0087] The insulating component (1) disclosed herein preferably exhibits non-melt-forming properties. The non-melt-forming properties will be described later.

[0088] The insulating component (1) disclosed herein can be manufactured by molding a raw material composition containing PTFE into a desired shape. The form of the raw material composition is not limited and can be a powder, dispersion, etc., preferably a powder.

[0089] The aforementioned raw material PTFE can be manufactured through emulsion polymerization or suspension polymerization.

[0090] Emulsion polymerization can be carried out using known methods. For example, in the presence of an anionic fluorinated surfactant and a polymerization initiator, emulsion polymerization of the monomers (TFE and, if necessary, modified monomers) required to construct the aforementioned PTFE is carried out in an aqueous medium, thereby obtaining an aqueous dispersion containing particles (primary particles) of the aforementioned PTFE. In the above emulsion polymerization, chain transfer agents, buffers, pH adjusters, stabilizing agents, dispersion stabilizers, free radical scavengers, etc., may be used as needed.

[0091] The obtained aqueous dispersion is precipitated to obtain a wet powder, which is then dried to obtain the raw material PTFE powder. Precipitation and drying can be carried out by known methods.

[0092] Suspension polymerization can be carried out as follows: monomers such as TFE, an aqueous medium, and other additives as needed are added to a reactor; the contents of the reactor are stirred; the reactor is then maintained at a specified polymerization temperature; a specified amount of polymerization initiator is added to initiate the polymerization reaction. After the polymerization reaction begins, monomers such as TFE, polymerization initiators, chain transfer agents, etc., may be added as needed, depending on the desired outcome.

[0093] The obtained suspended polymer particles can be washed and then crushed, or crushed particles can be made by washing and crushing the obtained suspended polymer particles at the same time.

[0094] The moistened pulverized particles can also be dehydrated and further dried. Drying is carried out to remove moisture from the pulverized particles obtained by pulverization.

[0095] After the suspended polymer particles are pulverized, the pulverized particles can be classified using known methods such as air classification.

[0096] The obtained pulverized particles can also be granulated using well-known granulation methods.

[0097] The physical properties of the obtained PTFE can be adjusted by changing the polymerization and post-processing conditions.

[0098] For example, in emulsion polymerization, by reducing the amount of polymerization initiator, reducing the amount of chain transfer agent, and using free radical scavengers, it is possible to increase the endothermic peak temperature, reduce the standard specific gravity, and increase the melt viscosity.

[0099] In the post-treatment of emulsion polymerization, the decomposition temperature can be increased by setting the drying temperature above 150°C.

[0100] In suspension polymerization, reducing the amount of polymerization initiator, reducing the amount of chain transfer agent, and preferably not using them at all, can increase the endothermic peak temperature, reduce the standard specific gravity, and increase the melt viscosity. In post-treatment, cleaning and drying at a temperature above 150°C can increase the decomposition temperature.

[0101] There are no particular limitations on the method for molding the raw material composition; any known molding method may be used.

[0102] When using powders obtained through emulsion polymerization, for example, the powder of the raw material composition can be mixed with an extrusion aid and then extruded into a paste. The extrusion aid can be removed by drying. Compression molding of the raw material composition powder is also preferred. The dispersion of the raw material composition can be coated onto a substrate such as glass cloth and dried. Firing can also be performed as needed.

[0103] When using powders obtained through suspension polymerization, molding methods such as compression molding, plunger extrusion molding, and isobaric compression molding can be employed. Sintering can also be performed as needed.

[0104] PTFE molded bodies can also be processed through machining such as cutting to produce molded bodies with the desired shape. For example, by cutting PTFE molded bodies, PTFE sheets can be obtained.

[0105] This disclosure also provides an insulating component for an electrochemical device exhibiting non-melt-forming properties (hereinafter also referred to as the insulating component (2) of this disclosure).

[0106] The insulating component (2) of this disclosure maintains its insulation properties even at high temperatures by exhibiting non-melt-forming properties. The insulating component (2) of this disclosure maintains good insulation properties even when the battery cell of the electrochemical device is at abnormally high temperatures (e.g., above 400°C), and can prevent short circuits in the battery cell and short circuits between components of the battery cell.

[0107] In this specification, non-melt formability is indicated as a melt flow rate (MFR) of less than 0.10 g / 10 min, preferably less than 0.01 g / 10 min.

[0108] The above MFR is the value obtained according to ASTM D1238, using a melt indexer at 372°C and a load of 5000g (total load), as the mass (g / 10 min) of polymer flowing out of a nozzle with an inner diameter of 2.095 mm and a length of 8 mm per 10 minutes.

[0109] The insulating component (2) disclosed herein may comprise a resin exhibiting non-melt-forming properties (hereinafter also referred to as non-melt-forming resin), fillers, etc. The aforementioned non-melt-forming resin may be a fluoropolymer or a non-fluoropolymer.

[0110] The aforementioned non-melt-forming resin has almost no fluidity at high temperatures. Therefore, from the perspective of further improving insulation, 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, it can be 600°C or lower, 550°C or lower, or 520°C or lower.

[0111] The above-mentioned thermal decomposition temperature is the temperature at which the mass reduction rate of the sample reaches 1% by mass under the conditions of air atmosphere and a heating rate of 10°C / min, using a differential thermal and thermogravimetric analysis apparatus (Hitachi High-Tech Science STA7200).

[0112] The aforementioned non-melt-forming resin is preferably cross-linked.

[0113] Examples of non-melt-forming resins include PTFE, ultra-high molecular weight polyethylene, thermosetting resins, and cross-linked resins. 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 cross-linked polyethylene are preferred, and PTFE and ultra-high molecular weight polyethylene are even more preferred.

[0114] As the aforementioned PTFE, examples of the same PTFE as that in the insulating component (1) of this disclosure can be cited.

[0115] The preferred weight-average molecular weight of the aforementioned ultra-high molecular weight polyethylene is 1.0 × 10⁻⁶. 6 The above is preferred, and more preferably 2.0×10 6 In addition, it can be 7.0×10 7 The following can also be 7.0×10 6 the following.

[0116] The molecular weight of the aforementioned ultra-high molecular weight polyethylene was determined by polystyrene conversion using gel permeation chromatography (GPC).

[0117] Examples of commonly sold ultra-high molecular weight polyethylene include TIVAR UHMW-PE manufactured by Mitsubishi Chemical Advanced Materials and HI-ZEX MILLION manufactured by Mitsui Chemicals.

[0118] As the aforementioned filler, insulating fillers are preferred, while conductive fillers are not preferred. Examples of known insulating fillers include alumina, silicon oxide, magnesium oxide, anhydrous magnesium carbonate, magnesium hydroxide, silicon oxide, silicon nitride, boron nitride, and aluminum nitride; magnesium oxide, aluminum nitride, and boron nitride are preferred.

[0119] The insulating member (2) disclosed herein may contain components other than the aforementioned non-melt-molded resin, and preferably is substantially composed only of the aforementioned non-melt-molded resin. Therefore, the effects of the aforementioned non-melt-molded resin can be significantly utilized. "Substantially composed only of the aforementioned non-melt-molded resin" means that the content of the aforementioned non-melt-molded resin is 70% by mass or more relative to the aforementioned insulating member.

[0120] The content of the aforementioned non-melt-forming resin relative to the aforementioned insulating component is preferably 90.0% by mass or more, more preferably 95.0% by mass or more, further preferably 99.0% by mass or more, particularly preferably 99.9% by mass or more, and most preferably 99.95% by mass or more.

[0121] The insulating component (2) disclosed herein is preferably made only of the aforementioned non-melt-forming resin.

[0122] The insulating component (2) of this disclosure can be manufactured 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 can be a powder, dispersion, etc., preferably a powder. The molding method is also not limited; in addition to the molding method exemplified for the insulating component (1) of this disclosure, known molding methods can also be used.

[0123] The insulating component disclosed herein is a component used for electrical insulation in electrochemical devices. The insulating component of this disclosure can impart insulation between two or more conductive components of an electrochemical device, for example, it can impart insulation between a positive electrode and a negative electrode, or it can impart insulation between an electrode and other components (e.g., an outer casing such as a cover).

[0124] From the perspective of further improving the insulation performance at high temperatures, the heat absorption peak temperature of the insulating component disclosed herein is preferably 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. In addition, it is preferably 350°C or lower, and more preferably 346°C or lower.

[0125] Regarding the aforementioned endothermic peak temperatures, for insulating components that have not been heated to temperatures above 300°C, differential scanning calorimetry (DSC) was performed at a heating rate of 10°C / min. The temperature corresponding to the minimum point in the obtained heat of fusion curve is used. If there are two or more minimum points in a single fusion peak, each is taken as the endothermic peak temperature.

[0126] From the perspective of further improving the insulation performance at high temperatures, the melting point of the insulating component of the present invention is preferably 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. In addition, it is preferably 335°C or lower, and more preferably 330°C or lower.

[0127] Regarding the melting point mentioned above, differential scanning calorimetry (DSC) was performed on insulating components that had been heated to temperatures above 300°C at a heating rate of 10°C / min. The temperature corresponding to the minimum point in the obtained heat of fusion curve is given.

[0128] From the perspective of being able to delay the temperature rise when heating and preventing abnormally high temperatures from being reached in a short period of time, the heat of fusion of the insulating component disclosed herein is preferably 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, particularly preferably 60 J / g or more, and may also be 90 J / g or less, or 80 J / g or less.

[0129] The heat of fusion mentioned above is a value measured using a differential scanning calorimeter (DSC).

[0130] From the perspective of further improving the insulation performance at high temperatures, the heat of crystallization of the insulating component of the present invention is preferably 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. Alternatively, it can be 10 J / g or more, or 15 J / g or more.

[0131] The above-mentioned heat of crystallization is a value determined using a differential scanning calorimeter (DSC).

[0132] From the perspective of further improving insulation performance at high temperatures, the thermal decomposition temperature of the insulating component of the present invention is preferably 400°C or higher, more preferably 430°C or higher, and even more preferably 450°C or higher. Alternatively, it can be 600°C or lower, 550°C or lower, or 520°C or lower.

[0133] The above-mentioned thermal decomposition temperature is the temperature at which the mass reduction rate of the sample reaches 1% by mass under the conditions of air atmosphere and a heating rate of 10°C / min, using a differential thermal and thermogravimetric analysis apparatus (Hitachi High-Tech Science STA7200).

[0134] From the perspective of further improving insulation performance at high temperatures, the melt viscosity of the insulating component of the present invention at 380°C is preferably 1.0 × 10⁻⁶. 7 Pa·s or higher, more preferably 1.0 × 10⁻⁶ Pa·s or higher.8 Pa·s or higher. Alternatively, it can be 1.0 × 10⁻⁶ Pa·s or higher. 11 For values ​​below Pa·s, it can also be 5.0 × 10⁻⁶. 10 Pa·s and below.

[0135] The melt viscosity was quantified using a melt viscoelasticity measuring device MCR302 (manufactured by Anton Paar Japan Co., Ltd.). The measuring fixture used a parallel plate 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 was taken as the melt viscosity.

[0136] From the perspective of further improving insulation performance at high temperatures, the standard specific gravity (SSG) of the insulating component disclosed herein is preferably 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. Alternatively, it can be 2.130 or more, 2.140 or more, or 2.150 or more.

[0137] The above SSG was measured using samples molded according to ASTM D 4895 89 and determined by the water displacement method according to ASTM D 792.

[0138] The insulating components disclosed herein preferably have non-melting secondary workability. This non-melting secondary workability refers to the property that, according to ASTM D-1238 and D-2116, the melt flow rate cannot be determined at temperatures above the melting point; in other words, it has a property that it does not flow easily even in the melting temperature range.

[0139] From the perspective of further improving insulation at high temperatures, the insulation resistance of the insulating component disclosed herein after heating at 450°C is preferably 1 MΩ or more, more preferably 10 MΩ or more, and even more preferably 100 MΩ or more.

[0140] The insulation resistance described above was measured using the method described in the embodiments below.

[0141] The insulating component disclosed herein exhibits good sealing performance even at high temperatures, and is therefore suitable for use as a sealing component. A sealing component is a component used to prevent leakage of liquids or gases or the intrusion of liquids or gases from the outside. Examples of such sealing components include gaskets and encapsulations, with gaskets (insulating gaskets) being preferred.

[0142] The shape of the insulating member disclosed herein is not particularly limited; for example, it can be ring-shaped. Furthermore, the insulating member disclosed herein can have a circular, oblong, or quadrilateral shape with rounded corners when viewed from above, and has a through hole in its central portion.

[0143] The insulating member disclosed herein may have a cylindrical portion and a flange portion extending radially from an opening in the cylindrical portion. An insulating member having such a configuration can, for example, be suitably used for insulation of external terminals having a terminal head and a shaft portion. In this manner, when the shaft portion of the external terminal is configured to face the inner side of the electrochemical device (e.g., as described later...), Figure 1 , Figure 2 When the external terminal 2 is oriented in the same direction, the insulating member of this disclosure is preferably configured such that the opening in the cylindrical portion opposite to the flange portion faces the inner side of the electrochemical device. When the shaft portion of the external terminal is configured to face the outer side of the electrochemical device (with the same orientation as the external terminal 2), Figure 1 , Figure 2 In the case where the external terminal 2 is upside down, the insulating member of this disclosure is preferably configured such that the opening on the side opposite to the flange in the cylindrical portion faces the external side of the electrochemical device.

[0144] The use of an insulating member according to one embodiment of the present disclosure will be described with reference to the accompanying drawings.

[0145] exist Figure 1 In this embodiment, the electrochemical device 10 (e.g., a sealed square secondary battery) includes an outer can (not shown) and a cover 1. The outer can contains electrical components such as a generator (not shown), and the opening of the outer can is sealed by the cover 1.

[0146] The cover 1 is provided with an external terminal 2 (positive or negative terminal), which supplies external power to electrical components for energy storage, and also supplies power to external loads.

[0147] To ensure electrical insulation between the external terminal 2 and the cover 1, an insulating member (gasket) 3 and an insulating plate 4 are provided on the cover 1. The insulating member 3 is equivalent to the insulating member of this disclosure.

[0148] The external terminal 2 has a rectangular block-shaped terminal head 21 and a cylindrical shaft portion 22. The shaft portion 22 protrudes from the lower surface of the terminal head 21 (the inner side of the electrochemical device).

[0149] like Figure 1 As shown, the insulating member 3 has: a cylindrical portion 31; a flange portion 32 extending radially from an opening in the cylindrical portion 31; and a sidewall portion 33 rising from the periphery of the flange portion 32.

[0150] The cylindrical portion 31 is externally fitted into the shaft portion 22 of the external terminal 2, and the inner circumferential surface of the cylindrical portion 31 abuts against the outer circumferential surface of the shaft portion 22. In addition, the cylindrical portion 31 is inserted into the through hole of the cover 1, and the outer circumferential surface of the cylindrical portion 31 abuts against the inner circumferential surface of the through hole of the cover 1.

[0151] The flange portion 32 is held by the cover 1 and the external terminal 2. One abutting surface of the flange portion 32 abuts against the lower surface of the external terminal 2, and the other abutting surface of the flange portion 32 abuts against the surface of the cover 1.

[0152] With the cylindrical portion 31 and flange portion 32 of the insulating member 3 compressed, the insulating member 3 abuts against the external terminal 2 and the cover 1, thereby ensuring the airtightness of the electrochemical device.

[0153] The insulating component disclosed herein can be used alone or in combination with other components. The insulating component and other components of this disclosure can also be stacked. The aforementioned other components can be insulating components or sealing components.

[0154] The other components mentioned above preferably contain raw materials different from the insulating components disclosed herein, such as non-fluorinated resins like polyethylene (PE), polypropylene (PP), and polybutylene terephthalate (PBT), and fluoropolymers other than PTFE like tetrafluoroethylene / perfluoro(alkyl vinyl ether) copolymer (PFA).

[0155] Specific examples of combining the insulating components and other components of this disclosure are shown in Figure 2 and Figure 3 .

[0156] exist Figure 2 In this design, the insulating component (gasket) 3 comprises: component 3a, which contains PTFE and ensures insulation at high temperatures; and component 3b, which contains other raw materials (e.g., PP) and ensures sealing under normal, non-high-temperature conditions. Components 3a and 3b can be in contact or in an adjacent but non-contact state. An adjacent state means that the components are not in contact but are within a distance of 3 mm. It should be noted that even if the raw materials and functions of components 3a and 3b are interchanged, the same effect can be obtained.

[0157] exist Figure 3 In the middle, the insulating member (gasket) 3 has a structure in which member 3c and member 3d are stacked, member 3c contains PTFE and ensures insulation at high temperature, and member 3d contains other materials (e.g. PP) and ensures insulation under normal conditions without high temperature.

[0158] Components 3c and 3d can also be partially overlapping. Partial overlap means that when comparing components 3c and 3d, there are non-overlapping parts between them due to reasons such as non-overlapping ends, different widths or depths, positional offsets, or the presence of holes or gaps.

[0159] By making component 3c smaller than component 3d, material costs can be reduced. Conversely, by making component 3c larger than component 3d, insulation at high temperatures can be improved. Component 3c can also have holes or gaps. In this case, material costs can be reduced. The absence of holes or gaps improves insulation at high temperatures. Furthermore, component 3c can be divided into multiple parts. In this case, assembly sometimes becomes easier.

[0160] As a method for realizing the structure of the insulating component and other components of this disclosure, the following method can be exemplified.

[0161] (I) Fabricating a molded article pre-layered with the insulating components and other components of the present disclosure, and mounting it onto an electrochemical device.

[0162] (II) Lamination is performed by mounting and fixing the insulating components and other components of this disclosure as independent components to the electrochemical device.

[0163] (III) A portion of the surface of other components is coated with a material (PTFE, etc.) used to form the insulating components of this disclosure, and then the components are mounted on the electrochemical device.

[0164] As a specific method of covering in (III) above, the following methods can be exemplified.

[0165] (i) A dispersion of a material containing the insulating component of this disclosure (e.g., a PTFE dispersion) is applied to the surface of other components. Drying can then be performed. Subsequently, firing can also be carried out.

[0166] (ii) Wrap a sintered tape (e.g., a sintered PTFE tape) containing the insulating material of the present disclosure around the surface of other components.

[0167] (iii) Wrapping a strip of material containing the insulating element of this disclosure, either partially sintered or completely unsintered, around the surface of other components (e.g., a partially sintered or completely unsintered PTFE strip).

[0168] (iv) Attaching a partially or completely unburned tape (e.g., a partially or completely unburned PTFE tape) containing the insulating material of this disclosure to the surface of other components. Attachment may also be made via adhesive or bonding agent.

[0169] The insulating components disclosed herein are used in electrochemical devices such as batteries and capacitors.

[0170] Examples of batteries include lithium-ion batteries, sodium-ion batteries, and other rechargeable batteries.

[0171] A sodium-ion secondary battery is a secondary battery in which sodium ions in the electrolyte solution carry the electrical conduction. For example, sodium metal oxides can be used as the active material of 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 a raw material for the negative electrode.

[0172] There are no particular limitations on the capacitor, but electrochemical capacitors are preferred. Examples of electrochemical capacitors include 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, double-layer capacitors are particularly preferred.

[0173] The insulating component disclosed herein is suitable for use as an insulating component for batteries, and is particularly suitable for use as an insulating component for secondary batteries such as lithium-ion batteries and sodium-ion batteries.

[0174] The aforementioned secondary battery can be a secondary battery using electrolyte or a solid-state secondary battery.

[0175] It should be noted that, in this specification, a solid-state secondary battery is any secondary battery that contains a solid electrolyte. It can be a semi-solid-state secondary battery that contains both solid electrolyte and liquid components as electrolytes, or a fully solid-state secondary battery that contains only solid electrolyte as electrolyte.

[0176] The insulating component of this disclosure can also be used in a state of contact with the electrolyte of an electrochemical device, that is, it has a contact surface with the electrolyte. Even when used in such a state, the insulating component of this disclosure can maintain excellent insulation at high temperatures.

[0177] The term "electrolyte" here refers not only to the electrolyte itself but also to substances derived from it, which can be liquid, solid, or gas. These gases include, for example, gases produced by the evaporation of the electrolyte or gases generated by the decomposition of the electrolyte during charging and discharging.

[0178] The electrochemical device of this disclosure preferably includes a non-aqueous electrolyte. The insulating component of this disclosure can also be used in a state of contact with the non-aqueous electrolyte of the electrochemical device, that is, it has a liquid-contacting surface for contact with the non-aqueous electrolyte of the electrochemical device.

[0179] As the aforementioned non-aqueous electrolyte, a non-aqueous electrolyte obtained by dissolving a known electrolyte salt in a known organic solvent for dissolving electrolyte salts can be used.

[0180] As an organic solvent for dissolving electrolyte salts, there are no particular limitations; one or more of the following can be used: propylene carbonate, ethylene carbonate, butyl carbonate, γ-butyrolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, etc.; and fluorinated solvents such as fluoroethylene carbonate, fluoroether, fluorinated carbonate, etc.

[0181] Examples of electrolyte salts include LiClO4, LiAsF6, LiBF4, LiPF6, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiCl, LiBr, CH3SO3Li, CF3SO3Li, and cesium carbonate. From the viewpoint of good cycling characteristics, LiPF6, LiBF4, LiN(SO2CF3)2, LiN(SO2C2F5)2, or combinations thereof are particularly preferred.

[0182] The concentration of the electrolyte salt is preferably 0.8 mol / L or more, and more preferably 1.0 mol / L or more. Although the upper limit also depends on the organic solvent used to dissolve the electrolyte salt, it is usually 1.5 mol / L.

[0183] The solid electrolyte used in solid-state secondary batteries can be either a sulfide-based solid electrolyte or an oxide-based solid electrolyte. In particular, when using a sulfide-based solid electrolyte, there is an advantage in improved sheet flexibility.

[0184] As the aforementioned sulfide-based solid electrolyte, there are no particular limitations, and compounds selected from 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, Li₂S-P₂S₅ ...P₂S₅, Li₂S-P₂S₅, Li₂S-P₂S₅, Li₂S-P₂S₅, Li₂S-P₂S₅, Li₂S-P₂S₅, Li₂S-P₂S₅, Li₂S-P₂S₅, Li₂S-P₂S₅, Li₂S-P� 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 PS6-x-y Cl x (0.8≤x≤1.7, 0<y≤-0.25x+0.5), Li 10 SnP2S 12 A mixture of any one or more of the following.

[0185] The aforementioned sulfide-based solid electrolyte preferably contains lithium. Lithium-containing sulfide-based solid electrolytes are particularly preferred from the perspective of electrochemical devices with high energy density, especially for use in solid-state batteries that utilize lithium ions as carriers.

[0186] The oxide-based solid electrolytes are preferably compounds containing oxygen atoms (O), having ionic conductivity of metals belonging to Group 1 or Group 2 of the periodic table, and having electronic insulation.

[0187] As a specific example of a compound, Li can be cited. 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 It is at least one of the elements 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, nb satisfies 5 ≤ ​​nb ≤ 20), and Li. xc B yc M cc zc O nc (M cc It is an element selected from at least one of 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, nc satisfies 0 ≤ nc ≤ 6, and 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 greater than 0 and less than 0.1, M) eeThis represents a divalent metal atom. (D) ee (representing 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 Li3PO (4-3 / 2w) N w Li (where w satisfies w<1) has a LISICON (lithium superion conductor) type crystal structure 3.5 Zn 0.25 GeO4, La with a perovskite-type crystal structure 0.51 Li 0.34 TiO 2.94 La 0.55 Li 0.35 TiO3, LiTi2P3O with a NASICON (sodium superionic conductor) 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. In addition, ceramic materials in which elemental substitutions have been performed on LLZ are also known. For example, Li can be obtained by substituting a portion of LLZ with Al. 6.24 La3Zr2Al 0.24 O 11.98 Li 6.25 Al 0.25 La3Zr2O 12 A portion of the Li was replaced with Ta. 6.6 La3Zr 1.6 Ta 0.4 O 12 A portion of Li after Nb replacement 6.75 La3Zr 1.75 Nb 0.25 O 12Furthermore, examples include LLZ-based ceramic materials in which at least one element selected from the group consisting of Mg (magnesium) and A (where A is at least one element selected from the group consisting of Ca (calcium), Sr (strontium), and Ba (barium)) has been substituted for LLZ. Additionally, phosphorus compounds containing Li, P, and O are preferred. Examples include lithium phosphate (Li3PO4), LiPON (LiPON) and LiPOD (LiPOD in which a portion of the oxygen in lithium phosphate has been replaced with nitrogen). 1 (D 1 The alloy is selected from at least one of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, Au, etc. Alternatively, LiAl is also preferred. 1 ON(A 1 (The material is selected from at least one of Si, B, Ge, Al, C, Ga, etc.). Specific examples include Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2 and Li2O-Al2O3-SiO2-P2O5-TiO2.

[0188] The aforementioned oxide-based solid electrolyte preferably contains lithium. Lithium-containing oxide-based solid electrolytes are particularly preferred from the perspective of electrochemical devices with high energy density, especially for use in solid-state batteries that utilize lithium ions as carriers.

[0189] The aforementioned oxide-based solid electrolyte is preferably an oxide with a crystalline structure. From the perspective of good Li-ion conductivity, oxides with a crystalline structure are particularly preferred. Examples of oxides with a crystalline structure include perovskite-type (La) oxides. 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 them, garnet type is preferred.

[0190] The implementation methods have been described above. However, it should be understood that various changes can be made to the methods and specific circumstances without departing from the spirit and scope of the claims.

[0191] Example

[0192] The present disclosure will now be described in more detail by way of examples, but the present disclosure is not limited to these examples.

[0193] Various physical properties were determined by the following methods.

[0194] <Content of modified monomers>

[0195] Regarding the PPVE content in PTFE, a thin film disc was fabricated by pressing the sample. Based on the infrared absorbance obtained from FT-IR measurement of the thin film disc, a 995cm² sample was used. -1 absorbance / 935cm -1 Multiply the ratio of absorbance to light intensity by 0.14 to determine the content.

[0196] The PPVE content in PFA was determined using an NMR analyzer (e.g., the AVANCE300 high-temperature probe manufactured by Bruker BioSpin).

[0197] Standard Specific Gravity (SSG)

[0198] The samples were molded according to ASTM D4895 89 and the determination was performed using the water displacement method according to ASTM D792.

[0199] Heat of fusion

[0200] The obtained tablets were cut, and approximately 3 mg were accurately weighed and stored in a dedicated aluminum tray. Using an X-DSC7000 (manufactured by Hitachi High-Tech Science Corporation), the temperature was increased 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. Regarding the heat of fusion, a line was drawn from the melting peak temperature -40°C to the melting peak temperature +20°C on the obtained DSC chromatogram, and the heat was calculated from the area enclosed by the curve containing the peak and the line.

[0201] <Fever of Crystallization>

[0202] The obtained slices were cut, and approximately 3 mg was accurately weighed and stored in a dedicated aluminum tray. Using an X-DSC7000 (manufactured by Hitachi High-Tech Science Corporation), the temperature was increased to the crystallization peak temperature of +40°C at a rate of 10°C / min under a nitrogen atmosphere, held for 1 minute, and then decreased to the crystallization peak temperature of -60°C at a rate of 10°C / min. The heat of crystallization at the crystallization point was measured. It should be noted that the heat of crystallization was calculated as follows: a line was drawn from the crystallization peak temperature of -30°C to the point of +25°C on the obtained DSC chart, and the area enclosed by the curve containing the peak and the line was used to determine the value.

[0203] Melt viscosity

[0204] Quantitative analysis was performed using an MCR302 melt viscoelasticity measuring apparatus (manufactured by Anton Paar Japan Co., Ltd.). A parallel plate with a diameter of 7 mm was used as the measuring fixture. 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. In cases where the viscosity was too low, or where the polymer in the sample vaporized due to thermal decomposition, a value below 100 Pa·s was set.

[0205] <Melt Formability (MFR)>

[0206] According to ASTM D1238, using a melt indexer, the mass (g / 10 min) of polymer flowing from a nozzle with an inner diameter of 2.095 mm and a length of 8 mm per 10 minutes is determined at 372°C and a load of 5000 g (total load). Samples with an MFR of 0.10 g / 10 min or higher indicate melt moldability, while samples with an MFR of less than 0.10 g / 10 min do not indicate melt moldability (indicating non-melt moldability). It should be noted that a flowability of less than 0.10 g / 10 min is considered too low to determine an MFR. In cases of excessively high flowability, or where the polymer in the sample has vaporized due to thermal decomposition, a flowability of 100 g / 10 min or higher is used.

[0207] <Insulation Resistance>

[0208] Use the obtained slices, such as Figure 4 As shown in (a), test piece 11 was fabricated with a Φ3.5mm hole in the center of a square piece measuring 30mm × 30mm × 0.2mm thickness. Figure 4 In (a), a = 3.5 mm, b = 0.2 mm, c = d = 30 mm.

[0209] like Figure 4 As shown in (b), test piece 11 and gasket 12 ( Figure 4 In (b), e=6.5mm, f=18mm, g=1mm) are fixed by overlapping the test piece 11 and the washer 12 in such a way that the centers of the holes are aligned.

[0210] like Figure 5 As shown in (a), using the conical punch 13 (in) Figure 5 In (a), h=1mm, i=8mm, j=40mm) enlarge the hole of the test piece 11 to form a cylindrical sleeve portion that abuts against the inner circumferential surface of the hole of the washer 12.

[0211] like Figure 5 As shown in (b), pin 14, which has a disc-shaped base and a cylindrical shaft, is placed in... Figure 5In (b), the shaft portion (k=6mm, l=12mm, m=6mm, n=8mm) is inserted into the sleeve portion to obtain... Figure 6 The test assembly component 100 is shown.

[0212] like Figure 7 As shown in (a), a tubular fixture 101 is covered on the gasket 12 of the test assembly component 100, and along the tubular fixture 101... Figure 7 With a 5kg load applied in the direction of the arrow shown in (b), the test assembly 100 is placed inside the electric furnace.

[0213] Heat the material in an electric furnace to an initial temperature of 250°C, then increase the temperature at a rate of 10°C / min to a holding temperature of 450°C. Perform a heat treatment at the holding temperature for 10 minutes, then cool to room temperature. After cooling, remove the load and measure the resistance between washer 12 and pin 14 using an insulation tester (machine name: Digital Megohm Tester 3454, manufactured by Hioki Electric Co., Ltd.) with an applied voltage of 250V.

[0214] If the insulation resistance exceeds 100MΩ, it is determined that the insulation is present after heating at 450℃; if it is below 10Ω, it is determined that the insulation is not present after heating at 450℃.

[0215] Furthermore, the insulation performance is evaluated in the same way when the holding temperature is set to 350°C. If the insulation resistance exceeds 100MΩ, it is determined that the material has insulation properties after heating at 350°C; if it is below 10Ω, it is determined that the material has no insulation properties after heating at 350°C.

[0216] <Water vapor permeation test>

[0217] like Figure 8 As shown, 2g of water 42 is added to an aluminum alloy cup 41. A gasket 47 is inserted between the cup 41 and the gasket compression fixture 43, and the cover 44 is tightened with bolts 45 to compress the gasket 47. A spacer 46 is provided between the cover 44 and the cup 41 to adjust the compression rate of the gasket 47 to 37.5% or 58%.

[0218] The compression ratio is calculated using the following formula.

[0219]

[0220] The mass of the thus obtained permeability test fixture 40 was measured. The fixture 40 was placed in an 80°C electric furnace for 1000 hours, then removed and left at room temperature for 2 hours before its mass was measured. The water vapor permeability coefficient was calculated using the following formula. This operation was repeated three times, and the average water vapor permeability coefficient was calculated. The average value is recorded in Table 2.

[0221]

[0222] Example 1

[0223] PTFE powder (a TFE homopolymer obtained by suspension polymerization, SSG=2.159) was compressed and molded under a pressure of 30 MPa for 5 minutes. The mixture was then heat-treated in an electric furnace to 365°C at a rate of 50°C / min for 5.5 hours, followed by cooling to room temperature to obtain a molded body with a diameter of 50 mm. The molded body was then machined to obtain a PTFE sheet A with a thickness of 0.2 mm. PTFE sheet A exhibits non-melt-forming properties.

[0224] Using PTFE sheet A, various physical properties were determined using the method described above. The results are shown in Table 1.

[0225] The resulting Φ50mm molded body yields an annular gasket A with a square cross-section of Φ14.3mm inner diameter × Φ17.7mm outer diameter × 1.6mm height. Gasket A exhibits non-melt processability.

[0226] A water vapor transmission test was conducted using gasket A to determine the water vapor transmission coefficient. The results are shown in Table 2.

[0227] Example 2

[0228] A lubricant (trade name: Isopar G (registered trademark), manufactured by Exxon) was mixed with PTFE powder (a TFE homopolymer obtained by emulsion polymerization, SSG=2.172), and the paste was extruded using a sheet-shaped extrusion die. The mixture was then heat-treated at 230°C for 30 minutes to remove the lubricant, yielding a PTFE sheet B with a thickness of 0.2 mm. PTFE sheet B exhibits non-melt-forming properties.

[0229] Using PTFE sheet B, various physical properties were determined using the method described above. The results are shown in Table 1.

[0230] Similarly, a lubricant was mixed into the PTFE powder described above, and the paste was extruded using a die of RR100 as specified in ASTM D4895. The paste was then heat-treated at 30°C for 30 minutes to remove the lubricant, yielding PTFE round bars E with a diameter of approximately 2.5 mm. The PTFE round bars exhibit non-melt-forming properties.

[0231] A PTFE rod is bent into a circle, and the ends of the wire are overlapped by 3mm to form a gasket shape, with an inner diameter of 16mm, resulting in gasket B. Gasket B exhibits non-melt processability.

[0232] A water vapor transmission test was conducted using gasket B to determine the water vapor transmission coefficient. The results are shown in Table 2.

[0233] Example 3

[0234] PTFE powder (PPVE-modified PTFE obtained by suspension polymerization (TFE / PPVE=99.89 / 0.11 mass%), SSG=2.175) was used instead of the PTFE powder in Example 1, except that a PTFE sheet C with a thickness of 0.2 mm was obtained in the same manner as in Example 1. PTFE sheet C exhibits non-melt-forming properties.

[0235] Various physical properties were determined using PTFE sheet C using the method described above. The results are shown in Table 1.

[0236] Comparative Example 1

[0237] PFA granules (TFE / PPVE = 96.1 / 3.9% by mass, MFR = 15.3 g / 10 min) were melted at 370°C for 20 minutes under pressure on a hot plate, and then water-cooled while being pressurized at 1 MPa to obtain PFA sheets with a thickness of 0.2 mm. The PFA sheets show melt-forming properties.

[0238] Using PFA tablets, various physical properties were determined using the method described above. The results are shown in Table 1.

[0239] Comparative Example 2

[0240] Using PTFE powder (TFE homopolymer, MFR=22g / 10min) instead of the PFA granules of Comparative Example 1, a PTFE sheet D with a thickness of 0.2mm was obtained in the same manner as in Comparative Example 1. The PTFE sheet D exhibits melt-forming properties.

[0241] Using PTFE sheets D, various physical properties were determined using the method described above. The results are shown in Table 1.

[0242] Comparative Example 3

[0243] Polypropylene (PP) (trade name: Prime Polypro F227, manufactured by Prime Polymer Co., Ltd.) was used instead of the PFA granules in Comparative Example 1, and the hot plate pressing temperature was set to 280°C instead of 370°C. Otherwise, a PP sheet with a thickness of 0.2 mm was made in the same manner as in Comparative Example 1.

[0244] Various physical properties were determined using PP sheets and the methods described above. The results are shown in Table 1.

[0245] Similarly, PP is heated above its melting point to make a sheet, from which a circular annular gasket C with a square cross-section of Φ14.3mm inner diameter × Φ17.7mm outer diameter × 1.6mm height is obtained.

[0246] A water vapor transmission test was conducted using gasket C to determine the water vapor transmission coefficient. The results are shown in Table 2.

[0247] Comparative Example 4

[0248] Polybutylene terephthalate (PBT) (trade name: PBT Natural Color Unfilled, manufactured by Kurehaextron Co., Ltd.) was used instead of the PFA particles in Comparative Example 1, and the hot plate pressure temperature was set to 280°C instead of 370°C. Otherwise, a PBT sheet with a thickness of 0.2 mm was made in the same manner as in Comparative Example 1.

[0249] Using PBT sheets, various physical properties were determined using the method described above. The results are shown in Table 1.

[0250] Similarly, PBT is heated above its melting point to form a sheet, from which a circular annular gasket D with a square cross-section of Φ14.3mm inner diameter × Φ17.7mm outer diameter × 1.6mm height is obtained.

[0251] A water vapor transmission test was conducted using gasket D to determine the water vapor transmission coefficient. The results are shown in Table 2.

[0252] [Table 1]

[0253] [Table 2]

[0254] The PTFE sheet (PTFE composition) prepared in the examples is suitable for use as an insulating component for electrochemical devices.

[0255] Symbol Explanation

[0256] 10: Electrochemical Devices

[0257] 1: Cover

[0258] 2: External terminal

[0259] 21: Terminal head

[0260] 22: Shaft

[0261] 3: Insulating components (gaskets)

[0262] 31: Cylindrical section

[0263] 32: Flange portion

[0264] 33: Side wall portion

[0265] 4: Insulation board

[0266] 11: Test piece

[0267] 12: Washers

[0268] 13: Conical punch

[0269] 14: Sales

[0270] 100: Experimental assembly components

[0271] 101: Tubular fixture

[0272] 40: Transmission test fixture

[0273] 41: Cup

[0274] 42: Water

[0275] 43: Gasket compression fixture

[0276] 44: Cover

[0277] 45: Bolt

[0278] 46: Spacer

[0279] 47: Gasket

Claims

1. An insulating component for an electrochemical device comprising a polytetrafluoroethylene composition, the polytetrafluoroethylene composition comprising polytetrafluoroethylene, the polytetrafluoroethylene being a homopolymer of tetrafluoroethylene, or a modified polytetrafluoroethylene comprising tetrafluoroethylene units and less than 1.0% by mass of modified monomer units.

2. The insulating member according to claim 1, wherein, The heat of crystallization of the polytetrafluoroethylene composition is below 50 J / g.

3. The insulating member according to claim 1 or 2, wherein, The polytetrafluoroethylene composition exhibits non-melt-forming properties.

4. The insulating member according to any one of claims 1 to 3, wherein, The polytetrafluoroethylene is the modified polytetrafluoroethylene.

5. The insulating member according to any one of claims 1 to 4, wherein, The modified monomer is a perfluoro(propyl vinyl ether).

6. The insulating member according to any one of claims 1 to 5, wherein, The electrochemical device has a non-aqueous electrolyte.

7. The insulating member according to any one of claims 1 to 6, wherein it is a gasket.

8. The insulating member according to any one of claims 1 to 7, wherein, The content of the modified monomer unit in the modified polytetrafluoroethylene is less than 0.20% by mass relative to all polymer units.

9. The insulating member according to claim 8, wherein, The content of the polytetrafluoroethylene is 99.0% by mass or more relative to the polytetrafluoroethylene composition, and the content of the polytetrafluoroethylene composition is 99.0% by mass or more relative to the insulating component.

10. The insulating component according to claim 9, wherein the melt flow rate is less than 0.10 g / 10 min.

11. An insulating component for an electrochemical device, exhibiting non-melt-forming properties.

12. The insulating member according to claim 11, wherein the melt flow rate is less than 0.10 g / 10 min, the insulating member comprising polytetrafluoroethylene.

13. The insulating member according to any one of claims 1 to 12, wherein, The electrochemical device is a lithium-ion battery or a sodium-ion battery.

14. The insulating component according to any one of claims 1 to 13, wherein the heat of fusion is 50 J / g or more.

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