Container

Abstract

The purpose of the present disclosure is to provide a container in which fibrillation of polytetrafluoroethylene does not readily occur. The present invention relates to a container for filling polytetrafluoroethylene, which is a cylindrical container in which the inner wall of the side surface has a positive cone shape or an inverted cone shape.

Description

Technical Field

[0001] This disclosure relates to containers for filling polytetrafluoroethylene. Background Technology

[0002] Patent documents 1 and 2 describe the use of aqueous dispersions of polytetrafluoroethylene as binders for batteries.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2004-31179

[0006] Patent Document 2: Japanese Patent Application Publication No. 11-343317 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] The purpose of this disclosure is to provide a container that is not prone to fibrillation of polytetrafluoroethylene.

[0009] means for solving problems

[0010] This disclosure (1) is a container for filling polytetrafluoroethylene, the inner wall of which is a cylindrical shape that is either conical or inverted conical.

[0011] This disclosure (2) is the container described in this disclosure (1), wherein the polytetrafluoroethylene has an extrusion pressure of 5 MPa or more at a compression ratio of 100 and / or is capable of stretching.

[0012] This disclosure (3) is the container described in disclosure (1) or (2), wherein the polytetrafluoroethylene has an extrusion pressure of 5 MPa or more at a compression ratio of 100 and is capable of stretching.

[0013] This disclosure (4) is the container described in any one of (1) to (3) of this disclosure, wherein the extrusion pressure of the polytetrafluoroethylene at a compression ratio of 100 is 5 to 20 MPa.

[0014] This disclosure (5) is the container described in any one of (1) to (4) of this disclosure, wherein the above-mentioned polytetrafluoroethylene is used as an adhesive for electrochemical devices.

[0015] This disclosure (6) is the container described in any one of disclosures (1) to (5), wherein the difference between the inner diameter of the upper surface and the inner diameter of the lower surface is 5 to 100 mm.

[0016] This disclosure (7) is the container described in any one of disclosures (1) to (6), wherein the cone angle is 0.5° to 10°.

[0017] This disclosure (8) is a container as described in any one of disclosures (1) to (7), wherein the material is polypropylene that is substantially free of plasticizers.

[0018] This disclosure (9) is the container described in any one of disclosures (1) to (8), wherein the surface roughness of the inner wall is less than 1.00 μm.

[0019] This disclosure (10) is a container as described in any one of disclosures (1) to (9), wherein the container comprises: a body having an opening, a cover installed in the opening, and a clamp for fixing the cover.

[0020] This disclosure (11) is the container described in this disclosure (10), wherein the cover is installed on the opening in a state in which the step provided on the cover engages with the protrusion provided on the main body, and / or in a state in which the protrusion provided on the cover engages with the step provided on the main body.

[0021] This disclosure (12) is the container described in any one of disclosures (1) to (11), wherein the moisture content of the polytetrafluoroethylene is less than 0.050% by mass.

[0022] This disclosure (13) is the container described in any one of disclosures (1) to (12), wherein the apparent density of the polytetrafluoroethylene is 0.40 to 0.60 g / ml.

[0023] This disclosure (14) is the container described in any one of disclosures (1) to (13), wherein the apparent density of the polytetrafluoroethylene is 0.43 to 0.60 g / ml.

[0024] This disclosure (15) is the container described in any one of disclosures (1) to (14), wherein the particle size of the polytetrafluoroethylene powder is 300 to 700 μm.

[0025] This disclosure (16) is the container described in any one of disclosures (1) to (15), wherein the particle size of the polytetrafluoroethylene powder is 500 to 700 μm.

[0026] This disclosure (17) is the container described in any one of disclosures (1) to (16), wherein the standard specific gravity of the polytetrafluoroethylene is 2.200 or less.

[0027] This disclosure (18) is the container described in any one of disclosures (1) to (17), wherein the standard specific gravity of the polytetrafluoroethylene is 2.130 to 2.170.

[0028] This disclosure (19) is the container described in any one of disclosures (1) to (18), wherein the apparent density of the polytetrafluoroethylene is 0.43 to 0.60 g / ml, the particle size of the powder is 500 to 700 μm, and the standard specific gravity is 2.130 to 2.170.

[0029] This disclosure (20) is the container described in any one of disclosures (1) to (19), wherein the polytetrafluoroethylene is a homopolymer of tetrafluoroethylene or a modified polytetrafluoroethylene comprising a tetrafluoroethylene-based polymerization unit and a modified monomer-based polymerization unit.

[0030] This disclosure (21) is the container described in this disclosure (20), wherein the modified monomer is at least one selected from the group consisting of perfluoro(methyl vinyl ether) and hexafluoropropylene.

[0031] This disclosure (22) is the container described in any one of disclosures (1) to (21), wherein the container is filled with the aforementioned polytetrafluoroethylene.

[0032] This disclosure (23) is the container described in any one of disclosures (1) to (22), wherein the container is equipped with a desiccant.

[0033] This disclosure (24) is a method for preserving polytetrafluoroethylene, wherein the above-mentioned polytetrafluoroethylene is filled into a container described in any one of (1) to (23) of this disclosure for preservation.

[0034] This disclosure (25) is a container for filling polytetrafluoroethylene, wherein the mass of the polytetrafluoroethylene filled is less than 10 kg.

[0035] This disclosure (26) is the container described in this disclosure (25), wherein the mass of the polytetrafluoroethylene filled therein is less than 5 kg.

[0036] This disclosure (27) refers to the container described in this disclosure (25) or (26), wherein the particle size of the polytetrafluoroethylene powder is 100 μm or more and less than 600 μm.

[0037] This disclosure (28) is the container described in any one of disclosures (25) to (27), wherein the apparent density of the polytetrafluoroethylene is 0.35 to 0.48 g / ml.

[0038] This disclosure (29) is the container described in any one of disclosures (25) to (28), wherein the moisture content of the polytetrafluoroethylene is less than 0.050% by mass.

[0039] This disclosure (30) is the container described in any one of (25) to (29) of this disclosure, wherein the moisture content of the polytetrafluoroethylene is less than 0.005% by mass.

[0040] This disclosure (31) is the container described in any one of (25) to (30) of this disclosure, wherein the standard specific gravity of the polytetrafluoroethylene is 2.130 to 2.170.

[0041] This disclosure (32) is the container described in any one of disclosures (25) to (31), wherein the moisture content of the polytetrafluoroethylene is less than 0.005% by mass, the apparent density is 0.35 to 0.48 g / ml, the powder particle size is more than 100 μm and less than 600 μm, and the standard specific gravity is 2.130 to 2.170.

[0042] This disclosure (33) is the container described in any one of disclosures (25) to (32), wherein the polytetrafluoroethylene powder has a particle size of 100 μm or more and less than 300 μm, and / or an apparent density of 0.35 g / ml or more and less than 0.40 g / ml.

[0043] This disclosure (34) is a container as described in any one of (25) to (33) of this disclosure, wherein the container is filled with the aforementioned polytetrafluoroethylene.

[0044] Invention Effects

[0045] According to this disclosure, it is possible to provide containers that are not prone to fibrillation of polytetrafluoroethylene. Attached Figure Description

[0046] Figure 1 This is a schematic diagram illustrating an example of a container of this disclosure.

[0047] Figure 2 yes Figure 1 A magnified view of a portion of the container.

[0048] Figure 3 yes Figure 1 A schematic diagram of the clamps provided by the container.

[0049] Figure 4 This is a schematic diagram illustrating a variation of the container of this disclosure.

[0050] Figure 5 This is a schematic diagram illustrating a variation of the container of this disclosure.

[0051] Figure 6 This is a partially enlarged view of a modified example of the container disclosed herein.

[0052] Figure 7 This is a schematic diagram illustrating a variation of the container of this disclosure. Detailed Implementation

[0053] The inventors conducted research on polytetrafluoroethylene (PTFE) and found that PTFE, which is useful as a binder for electrochemical devices such as batteries, tends to fibrillate more easily when stored and transported in a filled container compared to conventional PTFE. While some fibrillation is not a major problem in applications using large quantities of PTFE, its impact is significant when used as a binder in electrochemical devices, even in small quantities. Therefore, there is a strong demand for suppressing fibrillation.

[0054] Furthermore, the inventors conducted further research and discovered that if the inner wall of the container is a cylindrical shape with a conical or inverted conical shape, the fibrillation of the filled polytetrafluoroethylene (PTFE) is suppressed, leading to the first disclosure. Additionally, the inventors discovered that by keeping the mass of PTFE filled in the container to 10 kg or less, the fibrillation of the filled PTFE is suppressed, leading to the second disclosure.

[0055] The following provides a detailed explanation of this disclosure.

[0056] The first disclosure pertains to a container for filling polytetrafluoroethylene, wherein the inner wall of the side is a cylindrical shape that is either conical or inverted conical.

[0057] Polytetrafluoroethylene (PTFE) filled in a container hardens due to the crushing and compaction of PTFE powder (granules) under its own weight. Typically, PTFE powder needs to be loosened before use, but it is believed that fibrillation occurs during the loosening of this hardened powder. The container disclosed in this first publication, by making the inner walls of the sides conical or inverted conical, makes it difficult for the force generated by its own weight to be applied to the PTFE powder, thus preventing compaction and inhibiting fibrillation.

[0058] In the container disclosed in the first book, the mass of PTFE filled is preferably 30 kg or less, more preferably 20 kg or less, and even more preferably 15 kg or less. The lower limit is not particularly limited, but is generally 1 kg or more.

[0059] The upper limit of the internal volume of the container disclosed in the first book is preferably 150L or less, more preferably 120L or less, even more preferably 100L or less, and even more preferably 80L or less. The lower limit is not particularly limited, but is preferably 5L or more, more preferably 10L or more, and even more preferably 20L.

[0060] Hereinafter, an example of the container disclosed in the first edition will be described with reference to the accompanying drawings.

[0061] like Figure 1 As shown, container 1 has a main body 2, a lid 3, and a clamp 4.

[0062] The main body 2 is a cylindrical component with inner walls 2a and outer walls 2b that are conical. PTFE is filled through the opening 2c on the upper surface. After filling with PTFE, a cover 3 is installed at the opening 2c of the main body 2 and fixed by a clamp 4, thereby sealing the interior of the main body 2.

[0063] The cover 3 is a circular component constructed to cover the opening 2c and sides of the main body 2. For example... Figure 2 As shown, a stepped step 3a is provided on the inner side of the cover 3 where it contacts the outer wall 2b, and a protrusion 2d is provided on the outer side of the opening 2c of the main body 2. The cover 3 is installed in the opening 2c with the step 3a and the protrusion 2d engaged. As a result, the airtightness of the interior of the main body 2 is improved.

[0064] Clamp 4 is a ring-shaped component used to fix the cover 3 to the body 2. For example... Figure 3 As shown, the clamp 4 is in an open-loop state before installation. After installation, it is closed and tightened by the mounting part 4a, thereby fixing the cover 3 to the main body 2. As a result, the internal airtightness of the main body 2 is improved.

[0065] The PTFE used in the binder of electrochemical devices requires low moisture content. With the above configuration, the interior of the main body 2 of container 1 is highly airtight, thus enabling the PTFE to be stored in a low-moisture state.

[0066] The difference between the inner diameter of the upper surface and the inner diameter of the lower surface of the main body 2 is preferably 5 mm or more, more preferably 10 mm or more, even more preferably 15 mm or more, particularly preferably 20 mm or more, and preferably 100 mm or less, more preferably 80 mm or less, even more preferably 60 mm or less, and particularly preferably 50 mm or less.

[0067] The inner diameter of the upper surface is preferably 250 mm or more, more preferably 300 mm or more, even more preferably 350 mm or more, particularly preferably 400 mm or more, and preferably 800 mm or less, more preferably 700 mm or less, and even more preferably 600 mm or less.

[0068] The inner diameter of the lower surface is preferably 200 mm or more, more preferably 250 mm or more, even more preferably 300 mm or more, particularly preferably 350 mm or more, and preferably 750 mm or less, more preferably 650 mm or less, even more preferably 600 mm or less, and particularly preferably 550 mm or less.

[0069] The cone angle of the inner wall 2a is preferably 0.5° or more, more preferably 1° or more, even more preferably 1.5° or more, particularly preferably 2° or more, and preferably 10° or less, more preferably 9° or less, even more preferably 8° or less, even more preferably 7° or less, even more preferably 6° or less, and particularly preferably 5° or less. The preferred range of the cone angle of the outer wall 2b is the same as that of the inner wall 2a.

[0070] The aforementioned cone angle refers to the angle of inclination of the wall surface relative to the normal (see reference). Figure 1 (The "cone angle A" in the text).

[0071] The taper ratio of container 1 is preferably 0.01 or more, more preferably 0.02 or more, even more preferably 0.03 or more, even more preferably 0.04 or more, particularly preferably 0.05 or more, and preferably 0.20 or less, more preferably 0.19 or less, even more preferably 0.18 or less, even more preferably 0.17 or less, even more preferably 0.16 or less, and particularly preferably 0.15 or less.

[0072] The aforementioned taper ratio is a value defined by |inner diameter of the upper surface of body 2 - inner diameter of the lower surface of body 2| / height of body 2.

[0073] The height of the main body 2 is preferably 200 mm or more, more preferably 250 mm or more, even more preferably 300 mm or more, and preferably 500 mm or less, more preferably 450 mm or less, and even more preferably 400 mm or less.

[0074] The container 1 (particularly the body 2 and lid 3 in contact with PTFE) is preferably made of polypropylene that is substantially free of plasticizers. This suppresses the mixing of impurities into the PTFE.

[0075] Essentially, "plasticizer-free" means that the plasticizer content relative to polypropylene is less than 1.0% by mass.

[0076] The surface roughness of the inner wall 2a is preferably below 1.00 μm. This suppresses fibrillation of PTFE caused by contact with the inner wall 2a. The lower limit is not particularly limited, but is typically around 0.20 μm.

[0077] The surface roughness mentioned above was calculated as follows: The surface was observed at 5x magnification using a VK-X1000 series shape analysis laser microscope manufactured by KEYENCE Corporation. The arithmetic mean roughness of the obtained image was measured at a distance of 2.5 mm using the analysis application included with the device. Similarly, images of a total of 3 locations were taken and the arithmetic mean roughness was measured. The average of these three locations was used to calculate the roughness.

[0078] It should be noted that the first publicly disclosed container is not limited to the above-mentioned form, and may also be other forms.

[0079] For example, such as Figure 4 As shown, the inner wall 2a and outer wall 2b of the side can also be inverted cone shape.

[0080] In addition, such as Figure 5 As shown, it can also be a shape where the inner wall 2a of the side is a regular cone and the outer wall 2b is not a cone (a straight line along the normal).

[0081] In addition, such as Figure 6 As shown, it can also be the same as Figure 2 In the opposite configuration, a protrusion 3b is provided on the inner side of the cover 3 where it contacts the outer wall 2b, and a stepped step 2e is provided on the outer side of the opening 2c of the main body 2. The cover 3 is installed on the opening 2c with the protrusion 3b and the step 2e engaged.

[0082] The second disclosure is a container for filling polytetrafluoroethylene (PTFE), wherein the mass of the PTFE being filled is less than 10 kg.

[0083] The container disclosed in the second book contains less than 10 kg of PTFE, so the force generated by its own weight is not easily applied to the PTFE powder, making it less likely to be compacted, thus inhibiting fibrillation.

[0084] Furthermore, the container disclosed in the second book is preferably filled with PTFE powder with a low apparent density. Therefore, the force generated by its own weight is not easily applied to the PTFE powder, making it less prone to compaction and thus suppressing fibrillation.

[0085] In the container of the second invention, the mass of PTFE filled is preferably 8 kg or less, more preferably 6 kg or less, and even more preferably 5 kg or less. The lower limit is not particularly limited, but is generally 1 kg or more.

[0086] The upper limit of the internal volume of the container disclosed in the second book is preferably 75L or less, more preferably 60L or less, even more preferably 50L or less, and even more preferably 40L or less. The lower limit is not particularly limited, but is preferably 5L or more, and more preferably 10L or more.

[0087] The container disclosed in the second book can be a cylinder with inner walls of a conical or inverted cone shape, or it can be a cylinder with inner walls of a non-conical shape (a straight line along the normal). From the perspective of suppressing fibrillation, a cylindrical shape with inner walls of a conical or inverted cone shape is preferred. As a container with inner walls of a conical or inverted cone shape, for example, a shape similar to the container disclosed in the first book can be cited ( Figures 1-6(The shape). A cylindrical container whose inner walls on the sides are not conical (straight lines along the normal), for example, can be cited as... Figure 7 The shape shown.

[0088] Hereinafter, the containers of the first and second disclosures will also be collectively referred to as the containers of this disclosure.

[0089] In order to maintain a dry state inside the container, a desiccant may be filled in the container. Specifically, examples of desiccant include silica gel, calcium oxide, and calcium chloride, with silica gel and calcium oxide being preferred, and silica gel being more preferred.

[0090] The desiccant can be in granular or flake form. It can be used inside packaging materials or exposed. It can also be applied to PTFE filling the container or to other locations on the inner surface of the container, such as the back of the lid.

[0091] When using existing containers, PTFE needs to be stored at low temperatures (5–20°C) to inhibit fibrillation. However, in the containers disclosed herein, fibrillation is not easily observed even at room temperature. Therefore, PTFE can be stored without the need for temperature control based on region or time, and it also has the advantage of less burden during storage.

[0092] This disclosure also relates to a preservation method, wherein PTFE is filled into a container disclosed herein for preservation. In this preservation method, PTFE can be preserved at room temperature (15–30°C (preferably 25–30°C)).

[0093] The following describes the PTFE filled in the container of this disclosure.

[0094] The aforementioned PTFE is suitable for use as a binder in electrochemical devices. Examples of electrochemical devices include lithium-ion secondary batteries, lithium-ion capacitors, capacitors (hybrid capacitors, double-layer capacitors), free radical batteries, solar cells (especially pigment-sensitized solar cells), lithium-ion primary batteries, fuel cells, various electrochemical sensors, electrochromic elements, electrochemical switching elements, aluminum electrolytic capacitors, and tantalum electrolytic capacitors. The binder can be used for electrodes or for solid electrolytes.

[0095] When using the above-mentioned PTFE as a binder for electrochemical devices, PTFE can be used alone or mixed with other materials (such as polymers other than PTFE).

[0096] The preferred form of the PTFE mentioned above is powder.

[0097] From the perspective of its usefulness as an adhesive for electrochemical devices such as batteries, and its ease of fibrillation, which makes this disclosure particularly effective, the PTFE is preferably extruded at a compression ratio (RR) of 100 with an extrusion pressure of 5 MPa or more and / or capable of stretching, more preferably extruded at a compression ratio (RR) of 100 with an extrusion pressure of 5 MPa or more and capable of stretching.

[0098] The extrusion pressure of the PTFE at a compression ratio (RR) of 100 is preferably 5 MPa or more, more preferably 10 MPa or more from the perspective of improving processability, adhesion and flexibility of electrodes, etc., further preferably 12 MPa or more, even more preferably 13 MPa or more, and particularly preferably 15 MPa or more.

[0099] Furthermore, from the perspective of improving processability, the extrusion pressure when RR is 100 is preferably 50 MPa or less, more preferably 40 MPa or less, even more preferably 35 MPa or less, even more preferably 30 MPa or less, even more preferably 25 MPa or less, and particularly preferably 20 MPa or less.

[0100] From the perspective of improving processability, adhesion and electrode flexibility, the extrusion pressure of the above-mentioned PTFE at RR of 300 is preferably 10 Pa or more, more preferably 15 MPa or more, even more preferably 20 MPa or more, even more preferably 25 MPa or more, and particularly preferably 30 MPa or more.

[0101] Furthermore, from the perspective of improving processability, the extrusion pressure when RR is 300 is preferably 45 MPa or less, and more preferably 40 MPa or less.

[0102] The extrusion pressure at RR of 100 was determined by the following method.

[0103] 50 g of PTFE powder and 10.25 g of hydrocarbon oil (trade name: Isopar E, manufactured by ExxonMobil) as an extrusion aid were mixed in a polyethylene container for 3 minutes. The mixture was then filled into the barrel of an extruder at room temperature (25 ± 2 °C), and a load of 0.47 MPa was applied to the piston inserted into the barrel and held for 1 minute. Extrusion was then carried out from the orifice at a screw speed of 18 mm / min. The ratio of the barrel's cross-sectional area to the orifice's cross-sectional area (compression ratio) was 100. During the latter half of the extrusion operation, the extrusion pressure (MPa) was obtained by dividing the load (N) at pressure equilibrium by the barrel's cross-sectional area.

[0104] The extrusion pressure at RR of 300 was determined by the following method.

[0105] 50 g of PTFE powder and 11.00 g of hydrocarbon oil (trade name: Isopar E, manufactured by ExxonMobil) as an extrusion aid were mixed in a polyethylene container for 3 minutes. The mixture was then filled into the barrel of an extruder at room temperature (25 ± 2 °C), and a load of 0.47 MPa was applied to the piston inserted into the barrel and held for 1 minute. Extrusion was then carried out from the orifice at a screw speed of 18 mm / min. The ratio of the barrel's cross-sectional area to the orifice's cross-sectional area (compression ratio) was 300. During the latter half of the extrusion operation, the extrusion pressure (MPa) was obtained by dividing the load (N) at pressure equilibrium by the barrel's cross-sectional area.

[0106] The PTFE mentioned above can be stretchable or non-stretchable, but stretchable is preferred.

[0107] Being able to stretch means that a stretched body can be obtained in the following tensile tests.

[0108] The strips (beading) obtained by extruding the paste with an RR of 100 were dried at 230°C for 30 minutes to remove the lubricant. The dried strips were then cut into appropriate lengths and placed in an oven heated to 300°C, where they were stretched at a stretching speed of 1000% / second.

[0109] From the perspective of improving processability, adhesion and flexibility of electrodes, the above-mentioned PTFE is preferably capable of stretching up to 25 times.

[0110] Whether it can be stretched to 25 times its original length can be confirmed by the following tensile test.

[0111] The strips obtained by extruding the paste with an RR of 100 were dried at 230°C for 30 minutes to remove the lubricant. The dried strips were then cut into appropriate lengths and placed in an oven heated to 300°C. Inside the oven, the strips were stretched at a stretching speed of 1000% / second to 25 times their original length before the stretching test. If the strips did not break during the stretching, they were deemed capable of being stretched to 25 times their original length.

[0112] The PTFE described above is preferably substantially free of moisture. This allows for a wide selection of electrode active materials for combination, thus providing an advantage in the production process. "Substantially free of moisture" means that the moisture content relative to the PTFE is 0.050% by mass or less.

[0113] The moisture content is preferably 0.040% by mass or less, more preferably 0.020% by mass or less, even more preferably 0.010% by mass or less, even more preferably 0.005% by mass or less, and particularly preferably 0.002% by mass or less.

[0114] The moisture content was determined using the following method.

[0115] The mass of PTFE powder before and after heating at 150℃ for 2 hours was determined and calculated using the following formula. Three samples were taken, and the mass was calculated separately. The average value was then used.

[0116] Moisture content (mass %) = [(mass of PTFE powder before heating (g)) - (mass of PTFE powder after heating (g))] / (mass of PTFE powder before heating (g)) × 100

[0117] From the perspective of improving processability, the apparent density of the PTFE is preferably 0.40 g / ml or more, more preferably 0.43 g / ml or more, even more preferably 0.45 g / ml or more, and even more preferably 0.48 g / ml or more. There is no particular upper limit, and it can be 0.60 g / ml.

[0118] The apparent density was determined according to JIS K 6892.

[0119] From the perspective of suppressing fibrillation, the apparent density of the above-mentioned PTFE is preferably less than 0.50 g / ml, more preferably less than 0.48 g / ml, even more preferably less than 0.45 g / ml, even more preferably less than 0.40 g / ml, particularly preferably less than 0.40 g / ml, and preferably more than 0.20 g / ml, more preferably more than 0.25 g / ml, even more preferably more than 0.30 g / ml, and particularly preferably more than 0.35 g / ml.

[0120] From the perspective of improving processability, the particle size of the PTFE powder is preferably 300 μm or more, more preferably 450 μm or more, even more preferably 500 μm or more, even more preferably 550 μm or more, particularly preferably 600 μm or more, and preferably 1000 μm or less, more preferably 900 μm or less, even more preferably 800 μm or less, and particularly preferably 700 μm or less.

[0121] The particle size of the powder was determined by laser diffraction. A HELOS & ROD OS system (trade name, manufactured by SYMPATEC) was used in a dry process. For the powder being measured dispersed by compressed air at a dispersion pressure of 2 bar, the measuring sensor detected the shadow of the powder being measured as reflected by the laser, and calculated the particle size distribution of the powder. The average particle size (50% cumulative particle size) d50 was then determined based on volume, and the measurement was performed accordingly.

[0122] From the perspective of suppressing fibrillation, the particle size of the PTFE powder is preferably less than 600 μm, more preferably less than 400 μm, even more preferably less than 300 μm, particularly preferably less than 300 μm, and preferably more than 10 μm, more preferably more than 50 μm, and particularly preferably more than 100 μm.

[0123] From the perspective of improving processability, tensile strength, adhesion, and flexibility of electrodes, the standard specific gravity (SSG) of the PTFE is preferably 2.200 or less, more preferably 2.180 or less, even more preferably 2.170 or less, even more preferably 2.160 or less, even more preferably 2.150 or less, and even more preferably 2.145 or less.

[0124] The SSG value is preferably 2.130 or higher.

[0125] The above SSG was measured using samples molded according to ASTM D 4895 and determined by the water displacement method according to ASTM D 792.

[0126] From the perspective of high molecular weight, improved adhesion and electrode flexibility, the average primary particle size of the above-mentioned PTFE is preferably 350 nm or less, more preferably 330 nm or less, even more preferably 320 nm or less, even more preferably 300 nm or less, even more preferably 280 nm or less, particularly preferably 250 nm or less, and preferably 100 nm or more, more preferably 150 nm or more, even more preferably 170 nm or more, and particularly preferably 200 nm or more.

[0127] The average primary particle size was determined by the following method.

[0128] The PTFE aqueous dispersion was diluted with water to a solids concentration of 0.15% by mass. The transmittance per unit length of the resulting diluted latex was measured by 550 nm transmitted light, and the number-average particle size per unit length was determined by orientation measurement using transmission electron microscopy. A calibration curve was then constructed. Using this calibration curve, the number-average particle size was determined from the measured transmittance of 550 nm transmitted light for each sample, and this number-average primary particle size was used.

[0129] From the perspective of excellent processability, the average aspect ratio of the aforementioned PTFE can be 2.0 or less, preferably 1.8 or less, more preferably 1.7 or less, even more preferably 1.6 or less, even more preferably 1.5 or less, even more preferably 1.4 or less, even more preferably 1.3 or less, particularly preferably 1.2 or less, and most preferably 1.1 or less. Furthermore, the aforementioned average aspect ratio can be 1.0 or more.

[0130] The average length and width ratio was calculated as follows: Using a scanning electron microscope (SEM), PTFE powder or a PTFE aqueous dispersion diluted to a solid component concentration of about 1% by mass was observed. More than 200 randomly selected particles were image-processed, and the average length and width ratio was calculated from the average ratio of their major axis to minor axis.

[0131] The PTFE described above preferably has non-melting secondary processability. This non-melting secondary processability refers to the property that the melt flow rate cannot be determined at temperatures above the melting point according to ASTM D-1238 and D-2116; in other words, it refers to the property that it does not easily flow even in the melting temperature range.

[0132] The PTFE described above can be a homopolymer of tetrafluoroethylene (TFE), or a modified PTFE comprising TFE-based polymerization units (TFE units) and modified monomer-based polymerization units (hereinafter also referred to as modified monomer units). The modified PTFE may contain 99.0% by mass or more of TFE units and 1.0% by mass or less of modified monomer units. Alternatively, the modified PTFE may consist solely of TFE units and modified monomer units.

[0133] From the perspective of improving adhesion and electrode flexibility, the modified PTFE is preferred. From the perspective of improving processability, TFE homopolymer is preferred.

[0134] From the perspective of improving tensile strength, adhesion, and electrode flexibility, the modified PTFE preferably has a modified monomer unit content in the range of 0.00001% to 1.0% by mass relative to all polymer units. As a lower limit for the modified monomer unit content, 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 more preferred. As an upper limit for the modified monomer unit content, 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, 0.15% by mass is even more preferred, 0.10% by mass is even more preferred, 0.08% by mass is even more preferred, 0.05% by mass is particularly preferred, and 0.03% by mass is most preferred.

[0135] In this specification, the modified monomer unit mentioned above refers to the portion that is part of the molecular structure of PTFE and is derived from the modified monomer.

[0136] The content of each of the above-mentioned polymerization units can be calculated based on the type of monomer by appropriate combination of NMR, FT-IR, elemental analysis, and fluorescence X-ray analysis.

[0137] 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 trifluorochloroethylene; perfluorovinyl ethers; perfluoroallyl ethers; (perfluoroalkyl)ethylene; and ethylene. In addition, the modified monomers used can be one or more.

[0138] There are no particular limitations on the aforementioned perfluorovinyl ethers; for example, the following general formula (A) can be cited: CF2=CF-ORf(A)

[0139] (In the formula, Rf represents a perfluorinated organic group) This refers to perfluorinated unsaturated compounds, etc. In this specification, the term "perfluorinated organic group" refers to an organic group in which all hydrogen atoms bonded to carbon atoms are replaced by fluorine atoms. The aforementioned perfluorinated organic groups may possess ether-like oxygen.

[0140] Examples of perfluorovinyl ethers include perfluoro(alkylvinyl ether) [PAVE] in which Rf in the above general formula (A) is a perfluoroalkyl group having 1 to 10 carbon atoms. The number of carbon atoms in the perfluoroalkyl group is preferably 1 to 5.

[0141] Examples of perfluoroalkyl groups in the aforementioned PAVE include perfluoromethyl, perfluoroethyl, perfluoropropyl, perfluorobutyl, perfluoropentyl, and perfluorohexyl.

[0142] As examples of the aforementioned perfluorovinyl ethers, other examples include perfluoro(alkoxyalkyl) perfluorovinyl ethers in general formula (A) where Rf is 4 to 9 carbon atoms, and Rf is given by the following formula:

[0143] [Chemistry 1]

[0144]

[0145] (In the formula, m represents 0 or an integer from 1 to 4) The perfluorovinyl ethers and Rf of the groups shown are as follows:

[0146] [Chemistry 2]

[0147]

[0148] Perfluorovinyl ethers, etc., with groups represented by the formula (where n represents an integer from 1 to 4).

[0149] There is no particular limitation as to (perfluoroalkyl)ethylene (PFAE), for example, (perfluorobutyl)ethylene (PFBE) and (perfluorohexyl)ethylene.

[0150] Examples of perfluoroallyl ethers include, for instance, general formula (B):

[0151] CF2 = CF - CF2 - ORf 1 (B)

[0152] (where Rf) 1 Fluorine-containing monomers (representing perfluorinated organic groups) are shown in the image.

[0153] The above Rf 1 Preferably, it is a perfluoroalkyl group having 1 to 10 carbon atoms or a perfluoroalkoxyalkyl group having 1 to 10 carbon atoms. As the above-mentioned perfluoroallyl ether, it 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.

[0154] As the modified monomers described above, from the perspective of improving tensile strength, adhesion and electrode flexibility, it is preferable to select at least one from the group consisting of PAVE and HFP, and more preferably at least one from the group consisting of perfluoro(methyl vinyl ether) (PMVE) and HFP.

[0155] In addition, as other modified monomers mentioned above, from the viewpoint of being able to form compound tablets with excellent strength, it is preferable to select at least one of the group consisting of VDF, HFP, CTFE and PAVE, and more preferably at least one of the group consisting of VDF, HFP and CTFE.

[0156] From the perspective of improving heat resistance, the above-mentioned PTFE includes TFE units, VDF units and HFP units, and the total amount of VDF units and HFP units is less than 1.0% by mass relative to all polymer units, which is one of the preferred methods.

[0157] From the perspective of excellent processability, the aforementioned PTFE preferably has 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 in the particles. Examples of such modified PTFEs include the PTFE described in Japanese Patent Application Publication No. 2005-527652.

[0158] From the perspective of forming a compound tablet with excellent strength, the endothermic peak temperature of the aforementioned PTFE is preferably 320°C or higher, more preferably 325°C or higher, even more preferably 330°C or higher, even more preferably 335°C or higher, even more preferably 340°C or higher, even more preferably 342°C or higher, and particularly preferably 344°C or higher. Furthermore, the aforementioned endothermic peak temperature is preferably 350°C or lower.

[0159] The endothermic peak temperatures mentioned above are the temperatures corresponding to the minimum points in the melting heat curves obtained by differential scanning calorimetry (DSC) at a heating rate of 10°C / min for fluoropolymers without a history of heating to temperatures above 300°C. If a single melting peak contains two or more minimum points, each of these is used as an endothermic peak temperature.

[0160] The PTFE described above preferably exhibits more than one endothermic peak in the melting heat curve of 333°C to 347°C when heated at a rate of 10°C / min using a differential scanning calorimeter [DSC], and the melting heat at 290°C to 350°C calculated from the above melting heat curve is 62 mJ / mg or more.

[0161] From the perspective of forming a compound tablet with excellent strength, the number-average molecular weight (Mn) of the above-mentioned PTFE is preferably 3.0 × 10⁻⁶. 6 The above, more preferably 3.2×10 6 The above is further preferably 3.5×10 6 The above is further preferred to be 3.7×10 6 The above is particularly preferred, with 4.0×10⁻⁶ being the optimal value. 6 That's all. Furthermore, the preferred number-average molecular weight is 7.0 × 10⁻⁶. 6 The following is more preferably 6.5×10 6 The following is a further preferred value: 6.0 × 10 6 Hereinafter, 5.5×10 is even more preferred. 6 The following is particularly preferred: 5.0 × 10 6 the following.

[0162] The number-average molecular weights mentioned above were calculated from the heat of crystallization by measuring the cooling of fluoropolymer after melting using a differential scanning calorimeter (DSC) according to the method described in the following literature. Five measurements were performed, and the average of the three values ​​excluding the maximum and minimum values ​​was used.

[0163] Literature: Suwa, T.; Takehisa, M.; Machi, S., J. Appl. Polym. Sci. vol.17, pp.3253(1973).

[0164] The PTFE described above preferably does not substantially contain fluorinated compounds with a molecular weight of less than 1000. "Substantially does not contain fluorinated compounds" means that the amount of such fluorinated compounds is less than 25 ppb by mass relative to the PTFE.

[0165] The amount of the aforementioned fluorinated compound is more preferably less than 25 ppb by mass, even more preferably less than 10 ppb by mass, even more preferably less than 5 ppb by mass, even more preferably less than 3 ppb by mass, and particularly preferably less than 1 ppb by mass. The lower limit is not particularly limited and can be an amount below the detection limit.

[0166] The amount of the fluorinated compounds with a molecular weight of less than 1000 was determined by the following method.

[0167] Weigh 1g of the sample, add 10g (12.6ml) of methanol, and sonicate for 60 minutes to obtain an extract. Concentrate the extract appropriately by nitrogen purging, and determine the fluorine-containing compounds in the concentrated extract using LC / MS / MS. Extract the molecular weight information from the obtained LC / MS spectrum to confirm its consistency with the structural formula of the candidate fluorine-containing compounds. Prepare aqueous solutions of standard substances at five or more concentrations, and perform LC / MS analysis on each concentration. Plot the relationship between the concentration and the area of ​​the region relative to that concentration to create a calibration curve. Using the calibration curve, convert the area of ​​the LC / MS chromatogram of the fluorine-containing compounds in the extract into the concentration of the fluorine-containing compounds.

[0168] It should be noted that the detection limit in this assay method is 10 ppb by mass.

[0169] The amount of fluorinated compounds with a molecular weight of less than 1000 can also be determined by the following methods.

[0170] Weigh 1 g of the sample and add 10 g (12.6 ml) of methanol. Sonicate at 60 °C for 2 hours. After standing at room temperature, remove the solid components to obtain the extract. Concentrate the extract appropriately by nitrogen purging. Analyze the fluorine-containing compounds in the concentrated extract using LC / MS / MS. Extract the molecular weight information from the obtained LC / MS spectrum to confirm its consistency with the structural formula of the candidate fluorine-containing compounds. Prepare methanol standard solutions of fluorine-containing compounds at five known concentrations and analyze them using liquid chromatography-mass spectrometry. For each concentration range, use the methanol standard solution concentration and peak integral value to construct a calibration curve using a first approximation. Determine the content of fluorine-containing compounds in the extract using the calibration curve, and calculate the content of fluorine-containing compounds in the sample accordingly.

[0171] It should be noted that the detection limit in this assay method is 1 ppb.

[0172] Examples of fluorinated compounds with a molecular weight of 1000 or less include those with a molecular weight of 1000 g / mol or less and containing hydrophilic groups. The molecular weight of the aforementioned fluorinated compounds is preferably 800 or less, and more preferably 500 or less.

[0173] Polymer particles obtained by polymerization in the presence of fluorinated surfactants typically contain fluorinated surfactants in addition to PTFE. In this specification, fluorinated surfactants are the surfactants used during polymerization.

[0174] The fluorinated compounds with a molecular weight of less than 1000 mentioned above can be compounds that are not added during polymerization, or for example, compounds that are generated as a byproduct during polymerization.

[0175] It should be noted that the aforementioned fluorinated compounds with a molecular weight of 1000 or less, when including both anionic and cationic portions, refer to fluorinated compounds whose anionic portion has a molecular weight of 1000 or less. These fluorinated compounds with a molecular weight of 1000 or less do not contain PTFE.

[0176] As the aforementioned hydrophilic group, it can be, for example, -COOM, -SO2M, or -SO3M. Examples include -COOM and -SO3M (in each formula, M is H, a metal atom, or NR). 1 4. Imidazolium with or without substituents, pyridinium with or without substituents, or phosphonium with or without substituents, R 1 It is an anionic group such as H or an organic group.

[0177] As the aforementioned fluorinated surfactants, fluorinated surfactants with anionic moiety molecular weight of 1000 or less (anionic fluorinated surfactants) can also be used. The term "anionic moiety" refers to the portion of the aforementioned fluorinated surfactant other than the cationic moiety. For example, in F(CF2)... n1 In the case of COOM, it is "F(CF2)". n1 The "COO" part.

[0178] Examples of anionic fluorinated surfactants include those with the following general formula (N 0 ):X n0 -Rf n0 -Y 0 (N 0 )

[0179] (where X) n0 It can be H, Cl, or F. Rf n0Y is an alkylene group having 3 to 20 carbon atoms, in a chain, branched, or cyclic form, with some or all of its H atoms substituted by F. This alkylene group may contain more than one ether bond, and some of its H atoms may be substituted by Cl. 0 The compound shown is an anionic group.

[0180] Y 0 The anionic group can be -COOM, -SO2M or -SO3M.

[0181] M represents H, a metal atom, and NR. 1 4. Imidazolium with or without substituents, pyridinium with or without substituents, or phosphonium with or without substituents, R 1 It is an H or an organic group.

[0182] Examples of metal atoms mentioned above include alkali metals (Group 1) and alkaline earth metals (Group 2), such as Na, K, or Li.

[0183] As R 1 It can be H or C 1-10 The organic group can be H or C. 1-4 The organic group can be H or C. 1-4 Alkyl groups.

[0184] M can be H, a metal atom, or NR. 1 4 can be H, alkali metals (Group 1), alkaline earth metals (Group 2), or NR. 1 4 can be H, Na, K, Li or NH4.

[0185] The above Rf n0 In this process, more than 50% of the hydrogen atoms can be replaced by fluorine.

[0186] The aforementioned fluorinated surfactant can be a single fluorinated surfactant or a mixture containing two or more fluorinated surfactants.

[0187] Examples of fluorinated surfactants include compounds with the following formula. Fluorinated surfactants can also be mixtures of these compounds.

[0188] F(CF2)7COOM、

[0189] F(CF2)5COOM,

[0190] H(CF2)6COOM,

[0191] H(CF2)7COOM,

[0192] CF3O(CF2)3OCHFCF2COOM,

[0193] C3F7OCF(CF3)CF2OCF(CF3)COOM,

[0194] CF3CF2CF2OCF(CF3)COOM,

[0195] CF3CF2OCF2CF2OCF2COOM,

[0196] C2F5OCF(CF3)CF2OCF(CF3)COOM,

[0197] CF3OCF(CF3)CF2OCF(CF3)COOM,

[0198] CF2ClCF2CF2OCF(CF3)CF2OCF2COOM,

[0199] CF2ClCF2CF2OCF2CF(CF3)OCF2COOM,

[0200] CF2ClCF(CF3)OCF(CF3)CF2OCF2COOM,

[0201] CF2ClCF(CF3)OCF2CF(CF3)OCF2COOM, and

[0202] [Chemistry 3]

[0203]

[0204] (In each formula, M represents H, a metal atom, and NR) 1 4. Imidazolium with or without substituents, pyridinium with or without substituents, or phosphonium with or without substituents. R 1 (It is an H or organic group).

[0205] The PTFE described above preferably does not substantially contain any of the fluorinated compounds shown in the above formula.

[0206] In the above formulas, M can be H, a metal atom, or NR. 1 4 can be H, alkali metals (Group 1), alkaline earth metals (Group 2), or NR. 1 4 can be H, Na, K, Li or NH4.

[0207] R 1 It can be H or C 1-10 The organic group can be H or C. 1-4 The organic group can be H or C. 1-4 Alkyl groups.

[0208] If the PTFE does not substantially contain any of the fluorinated compounds shown in the above formula, it can further suppress gas generation and the deterioration of battery characteristics, and can also further improve electrode strength.

[0209] Substantively not containing any of the fluorinated compounds shown in the above formula means that the amount of the fluorinated compound is less than 25 ppb by mass relative to the PTFE mentioned above.

[0210] The amount of the aforementioned fluorinated compound is preferably less than 25 ppb by mass, more preferably less than 10 ppb by mass, even more preferably less than 5 ppb by mass, even more preferably less than 3 ppb by mass, and particularly preferably less than 1 ppb by mass. The lower limit is not particularly limited and can be an amount below the detection limit.

[0211] The PTFE described above preferably does not substantially contain the following general formula:

[0212] [C n-1 F 2n-1 COO - M + ]

[0213] (In the formula, n is an integer from 9 to 14, preferably an integer from 9 to 12, M) + (Represents a cation.) The fluorinated compound shown is used to suppress gas generation and the deterioration of battery characteristics, and also to improve sheet strength.

[0214] The cation M that constitutes the above formula + The M is the same as the M mentioned above.

[0215] Substantively not containing the fluorinated compound shown in the above formula means that the amount of the fluorinated compound is less than 25 ppb by mass relative to the above PTFE.

[0216] The amount of the aforementioned fluorinated compound is preferably less than 25 ppb by mass, more preferably less than 10 ppb by mass, even more preferably less than 5 ppb by mass, even more preferably less than 3 ppb by mass, and particularly preferably less than 1 ppb by mass. The lower limit is not particularly limited and can be an amount below the detection limit.

[0217] The embodiments have been described above; however, it should be understood that various changes in form and details may be made without departing from the spirit and scope of the claims.

[0218] Example

[0219] Next, experimental examples will be given to illustrate this disclosure, but this disclosure is not limited to these experimental examples.

[0220] Standard Specific Gravity (SSG)

[0221] Using samples formed according to ASTM D4895 89, the measurement is carried out by the water displacement method according to ASTM D 792.

[0222] <RR100 Extrusion Pressure (extrusion pressure at a compression ratio of 100)>

[0223] Mix 50 g of PTFE powder and 10.25 g of hydrocarbon oil (trade name: Isopar E, manufactured by ExxonMobil Corporation) as an extrusion aid in a polyethylene container for 3 minutes. Fill the above mixture into the barrel of the extruder at room temperature (25 ± 2 °C), apply a load of 0.47 MPa to the piston inserted into the barrel and hold for 1 minute. Then, extrude from the hole at a screw speed of 51 cm / min. The ratio of the cross-sectional area of the barrel to the cross-sectional area of the hole is 100. In the latter half of the extrusion operation, the value obtained by dividing the load (N) at the time when the pressure reaches the equilibrium state by the cross-sectional area of the barrel is used as the extrusion pressure (MPa).

[0224] <Tensile Test>

[0225] The tensile test is carried out by the following method according to the method described in Japanese Patent Laid-Open No. 2002-201217.

[0226] Heat the above-mentioned strip obtained by paste extrusion at 230 °C for 30 minutes to remove the lubricant from the strip. Then, cut the strip (extrusion molded body) into an appropriate length, fix each end to the chuck in such a way that the chuck interval is 1.5 inches (38 mm), and heat it to 300 °C in an air circulation furnace. Then, separate the chucks at a desired speed (elongation speed) to a separation distance corresponding to the desired elongation (total elongation) to carry out a tensile test (elongation test). This elongation method is essentially carried out according to the method disclosed in U.S. Patent No. 4,576,869, except that the extrusion speed (not 84 cm / min but 51 cm / min) is different. "Elongation" refers to the increase in length caused by stretching, usually expressed as a ratio to the original length. The elongation speed in the elongation method is 1000% / second, and the above-mentioned total elongation is 2400%. The case where no breakage occurs during stretching in the above-mentioned tensile test is regarded as capable of stretching, and the case where breakage occurs during stretching is regarded as incapable of stretching.

[0227] <Apparent Density>

[0228] The measurement is carried out according to JIS K6892.

[0229] <Particle Size of Powder>

[0230] The particle size distribution is determined by laser diffraction. A HELOS & ROD OS system (trade name, manufactured by SYMPATEC) is used in a dry manner. For the powder being tested dispersed by compressed air at a dispersion pressure of 2 bar, the measuring sensor detects the shadow of the powder being tested as reflected by the laser, and the particle size distribution is calculated from this. The average particle size (50% cumulative particle size) d50 is then determined on a volume basis. The particle size is equal to the particle size corresponding to 50% of the cumulative particle size distribution.

[0231] Moisture content

[0232] The mass of approximately 20g of PTFE powder before and after heating at 150℃ for 2 hours was determined using the following formula. Three samples were taken, and the mass was calculated separately. The average mass was then used.

[0233] Moisture content (mass %) = [(mass of PTFE powder before heating (g)) - (mass of PTFE powder after heating (g))] / (mass of PTFE powder before heating (g)) × 100

[0234] <Powder agglomeration>

[0235] Take 60g of the stored PTFE powder out of the container, sieve it through a sieve (1.54mm mesh), and determine the mass of the lumps remaining on the sieve.

[0236] Repeat the above steps 10 times and calculate the average mass of the lumps remaining on the sieve. Evaluate the powder's agglomeration tendency based on the calculated average mass (g) / 60 (g) × 100 (mass%). A smaller value indicates less powder agglomeration and a better powder quality.

[0237] <Preparation of the Positive Electrolyte Mixture>

[0238] Weigh the Li(Ni) as the positive electrode active material. 0.6 Mn 0.2 Co 0.2 O2 (NMC622), carbon black as a conductive additive, and PTFE powder as a binder were prepared such that the mass ratio of positive electrode active material: binder: conductive additive was 95:2:3. These materials were added to a mixer (Osaka Chemical Manufacturing: WB-1) and stirred at 25,000 rpm for 60 seconds to obtain a positive electrode mixture.

[0239] <Easy to bond>

[0240] In a vibrating mill, sieves with a 2.0 mm mesh, sieves with a 0.15 mm mesh, and a bottom support container are stacked longitudinally. The above-mentioned positive electrode mixture is placed in the upper sieve. After running at 50 rpm for 1 minute, the weight of the mixture that falls onto the support container from the sieve is measured.

[0241] The ease of adhesion (aggregation ease of the mixture) is evaluated based on the separation rate calculated by the following formula.

[0242] Exit rate = (W2 / W1) × 100 (%)

[0243] In the formula, W1 represents the total weight (g) of the mixture before the test, and W2 represents the weight (g) of the mixture that passed through the sieve.

[0244] Excellent: Dropout rate less than 1%

[0245] Good: detachment rate above 1% and less than 2%.

[0246] Acceptable: A withdrawal rate of 2% or higher but less than 3%

[0247] Undesirable: Dropout rate above 3%

[0248] Experimental Example 1

[0249] 15 kg of PTFE powder was added to a 60 L plastic container (material: polypropylene, plasticizer-free (0% by mass relative to polypropylene content), inner wall surface roughness: 0.23 μm) with a positive cone angle of 3.0°, a difference of 30 mm between the inner diameter of the upper and lower surfaces, and an inner wall surface roughness of 0.23 μm. The container was stored at 25°C for six months. The stored PTFE powder exhibited a caking property of 0.4% by mass and a moisture content of 0.002% by mass.

[0250] The positive electrode mixture was prepared using the above method, and its adhesion was evaluated. The detachment rate was 0.4% by mass, indicating excellent adhesion.

[0251] The PTFE powder used was the PTFE powder described in Example 1 of International Publication No. 2023 / 054709, with a standard specific gravity (SSG) of 2.159, an RR100 extrusion pressure of 15.1 MPa, the ability to be stretched, a powder particle size of 540 μm, an apparent density of 0.48 g / ml, and a moisture content of 0.002 by mass.

[0252] Experiment Example 2

[0253] The container was the same shape as in Experimental Example 1, equipped with a lid installed at the opening and a clamp for securing the container. The PTFE powder filling the container was the PTFE powder described in Example 2 of International Publication No. 2023 / 054707, with a standard specific gravity (SSG) of 2.145, an RR100 extrusion pressure of 17.4 MPa, stretchability, a particle size of 540 μm, an apparent density of 0.43 g / ml, and a moisture content of 0.000% by mass. Otherwise, it was stored for six months at 25°C, similar to Experimental Example 1. The stored PTFE powder exhibited a clumping rate of 0.3% by mass and a moisture content of 0.001% by mass.

[0254] The adhesion properties of the positive electrode mixture were evaluated, and the results showed a separation rate of 0.5% by mass, indicating excellent adhesion properties.

[0255] Experimental Example 3

[0256] The container has a stepped design on the lid that engages with a protrusion on the container body. Silica gel is used as a desiccant in the container. Otherwise, it is stored at 10°C for six months, similar to Example 2. The stored PTFE powder exhibits a clumping rate of 0.2% by mass and a moisture content of 0.000% by mass. The adhesion properties of the positive electrode mixture were evaluated, showing a detachment rate of 0.5% by mass and excellent adhesion.

[0257] Experiment Example 4

[0258] The PTFE powder filled in the container was the PTFE powder described in Example 18 of International Publication No. 2023 / 054723, with a standard specific gravity (SSG) of 2.170, an RR100 extrusion pressure of 5.6 MPa, non-stretchable, a particle size of 540 μm, an apparent density of 0.48 g / ml, and a moisture content of 0.001% by mass. Otherwise, it was stored for six months at 25°C, similar to Example 2. The stored PTFE powder exhibited a clumping rate of 0.1% by mass and a moisture content of 0.002% by mass. The adhesion of the positive electrode mixture was evaluated, and the detachment rate was 0.8% by mass, indicating excellent adhesion.

[0259] Experimental Example 5

[0260] 5 kg of PTFE powder was added to a 30 L plastic container (material: polypropylene, plasticizer-free (0% by mass relative to polypropylene content), with an inner wall surface roughness of 0.23 μm) containing a 0° positive cone angle, a 0 mm difference between the inner diameter of the upper and lower surfaces, and a volume of 0 mm. Otherwise, it was stored at 25°C for six months, similar to Example 1. The stored PTFE powder exhibited a clumping rate of 2.5% by mass and a moisture content of 0.005% by mass. The adhesion of the positive electrode mixture was evaluated, with a detachment rate of 2.1% by mass, indicating acceptable adhesion.

[0261] Experimental Example 6

[0262] The PTFE aqueous dispersion obtained from Manufacturing Example 1 of International Publication No. 2023 / 054713 was diluted to a solids concentration of 8.5% by mass, the liquid temperature was adjusted to 10°C, nitric acid was added, and the mixture was stirred at high speed in a container to induce coagulation. The mixture was then dried at 210°C to obtain PTFE powder. The obtained PTFE powder had a standard specific gravity (SSG) of 2.158, an RR100 extrusion pressure of 16.3 MPa, was stretchable, had a particle size of 145 μm, an apparent density of 0.35 g / ml, and a moisture content of 0.002% by mass. The obtained PTFE powder was stored for six months at 25°C, similar to Experimental Example 5. The stored PTFE powder exhibited a clumping rate of 1.5% by mass and a moisture content of 0.005% by mass. The adhesion of the positive electrode mixture was evaluated, and the detachment rate was 1.3% by mass, indicating good adhesion.

[0263] Experimental Example 7

[0264] A plastic container (material: polypropylene, plasticizer-free (0% by mass relative to polypropylene content), with an inner wall surface roughness of 0.23 μm) and a cone angle of 0° (i.e., the difference between the inner diameter of the upper and lower surfaces is 0 mm) was used, and the PTFE powder was stored in the same manner as in Example 1. The PTFE powder exhibited agglomeration of 5.6% by mass.

[0265] The positive electrode mixture was prepared using the above method, and its adhesion was evaluated. The detachment rate was 3.6% by mass, indicating poor adhesion.

[0266] Explanation of reference numerals in the attached figures

[0267] 1: Container

[0268] 2: Main Body

[0269] 2a: Inner wall

[0270] 2b: outer wall

[0271] 2c: Opening

[0272] 2d: protrusion

[0273] 2e: Steps

[0274] 3: Cover

[0275] 3a: Steps

[0276] 3b: protrusion

[0277] 4: Fixture

[0278] 4a: Installation Department

[0279] A: Cone angle.

Claims

1. A container which is a container for filling polytetrafluoroethylene, wherein, The inner wall of the side surface is a right or inverted tapered cylinder.

2. The container of claim 1, wherein, The polytetrafluoroethylene has an extrusion pressure of 5 MPa or more at a compression ratio of 100 and is stretchable.

3. The container of claim 1 or 2, wherein, The polytetrafluoroethylene has an extrusion pressure of 5 MPa or more at a compression ratio of 100 and is stretchable.

4. The container of any one of claims 1-3, wherein, The polytetrafluoroethylene has an extrusion pressure of 5 MPa to 20 MPa at a compression ratio of 100.

5. The container of any one of claims 1-4, wherein, The polytetrafluoroethylene is used as an adhesive for an electrochemical device.

6. The container of any one of claims 1-5, wherein, The difference between the upper surface inner diameter and the lower surface inner diameter is 5 mm to 100 mm.

7. The container of any one of claims 1-6, wherein, The taper angle is 0.5° to 10°.

8. The container of any one of claims 1-7, wherein, The material is polypropylene substantially free of plasticizers.

9. The container of any one of claims 1-8, wherein, The surface roughness of the inner wall is 1.00 μm or less.

10. The container of any one of claims 1-9, wherein, The container has a main body having an opening, a lid attached to the opening, and a clamp that fixes the lid.

11. The container of claim 10, wherein, The lid is attached to the opening in a state in which a step provided in the lid engages with a protrusion provided in the main body and / or in a state in which a protrusion provided in the lid engages with a step provided in the main body.

12. The container of any one of claims 1-11, wherein, The polytetrafluoroethylene has a moisture content of 0.050 mass% or less.

13. The container of any one of claims 1-12, wherein, The polytetrafluoroethylene has an apparent density of 0.40 g / ml to 0.60 g / ml.

14. The container of any one of claims 1-13, wherein, The polytetrafluoroethylene has an apparent density of 0.43 g / ml to 0.60 g / ml.

15. The container of any one of claims 1-14, wherein, The polytetrafluoroethylene has a powder particle diameter of 300 μm to 700 μm.

16. The container of any one of claims 1-15, wherein, The polytetrafluoroethylene has a powder particle diameter of 500 μm to 700 μm.

17. The container of any one of claims 1-16, wherein, The polytetrafluoroethylene has a standard specific gravity of 2.200 or less.

18. The container of any one of claims 1-17, wherein, The polytetrafluoroethylene has a standard specific gravity of 2.130 to 2.

170.

19. The container of any one of claims 1-18, wherein, The polytetrafluoroethylene has an apparent density of 0.43 g / ml to 0.60 g / ml, a powder particle diameter of 500 μm to 700 μm, and a standard specific gravity of 2.130 to 2.

170.

20. The container of any one of claims 1-19, wherein, The polytetrafluoroethylene is a homopolymer of tetrafluoroethylene or a modified polytetrafluoroethylene containing polymer units based on tetrafluoroethylene and polymer units based on a modifying monomer.

21. The container of claim 20, wherein, The modifying monomer is at least one selected from the group consisting of perfluoro(methyl vinyl ether) and hexafluoropropylene.

22. The container of any one of claims 1-21, wherein, The polytetrafluoroethylene is filled.

23. The container of any one of claims 1-22, wherein, The container has a moisture absorbent.

24. A method of preserving polytetrafluoroethylene, wherein, The polytetrafluoroethylene is stored in the container described in any one of claims 1 to 23.

25. A container which is a container for filling with polytetrafluoroethylene, wherein, The filled polytetrafluoroethylene has a mass of 10 kg or less.

26. The container of claim 25, wherein, The filled polytetrafluoroethylene has a mass of 5 kg or less.

27. The container of claim 25 or 26, wherein, The polytetrafluoroethylene has a powder particle diameter of 100 μm or more and less than 600 μm.

28. The container of any one of claims 25-27, wherein, The polytetrafluoroethylene has an apparent density of 0.35 g / ml to 0.48 g / ml.

29. The container of any one of claims 25-28, wherein, The polytetrafluoroethylene has a moisture content of 0.050 mass% or less.

30. The container of any one of claims 25-29, wherein, The polytetrafluoroethylene has a moisture content of 0.005 mass% or less.

31. The container of any one of claims 25-30, wherein, The polytetrafluoroethylene has a standard specific gravity of 2.130 to 2.

170.

32. The container of any one of claims 25-31, wherein, The polytetrafluoroethylene has a moisture content of 0.005 mass% or less, an apparent density of 0.35 g / ml to 0.48 g / ml, a powder particle diameter of 100 μm or more and less than 600 μm, and a standard specific gravity of 2.130 to 2.

170.

33. The container of any one of claims 25-32, wherein, The polytetrafluoroethylene has a powder particle size of 100 μm or more and less than 300 μm, and / or an apparent density of 0.35 g / ml or more and less than 0.40 g / ml.

34. The container of any one of claims 25-33, wherein, The polytetrafluoroethylene is filled.

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