Fluororesin composition, and molding

Abstract

To provide a fluororesin composition which is excellent in tensile characteristics and handleability regardless of containing a fluororesin which has a heating history at a temperature equal to or higher than a melting point, and a molding obtained from the fluororesin composition.SOLUTION: A fluororesin composition that does not exhibit melting flowability contains a fluororesin A which has a heating history at a temperature equal to or higher than a melting point and does not exhibit melting flowability, at least one kind of a fluororesin B selected from the group consisting of a fluororesin exhibiting melting flowability and a fluororesin which has no heating history at a temperature equal to or higher than a melting point and does not exhibit melting flowability, and a filler.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a fluororesin composition and a molded article. [Background technology]

[0002] Polytetrafluoroethylene (PTFE) that has been heated above its melting point for molding processes, etc., does not have sufficient physical properties when reused as a molding material, so recycling for molding purposes is limited.

[0003] Patent Documents 1 and 2 describe techniques for recycling PTFE that has been pulverized after baking and heated PTFE. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2019 / 244433 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-70233 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present disclosure is to provide a fluororesin composition that is excellent in tensile properties and handleability despite containing a fluororesin that has a history of being heated to a temperature equal to or higher than the melting point, and a molded article obtainable from the fluororesin composition. [Means for solving the problem]

[0006] The present disclosure (1) relates to a fluororesin A that has a history of being heated to a temperature equal to or higher than its melting point and does not exhibit melt fluidity; at least one fluororesin B selected from the group consisting of fluororesins that exhibit melt fluidity and fluororesins that do not exhibit melt fluidity and have no history of being heated to a temperature equal to or higher than their melting point; and a filler material. This is a fluororesin composition that does not exhibit melt flowability.

[0007] The present disclosure (2) is the fluororesin composition according to the present disclosure (1), which has one or more melting points in a temperature range below 333°C and one or more melting points in a temperature range of 333 to 360°C.

[0008] The present disclosure (3) is the fluororesin composition according to the present disclosure (1) or (2), which contains tetrafluoroethylene units and modified monomer units based on a modified monomer copolymerizable with tetrafluoroethylene.

[0009] The present disclosure (4) is the fluororesin composition according to the present disclosure (3), wherein the amount of the modified monomer unit is 1.0 mass % or less based on the total polymerized units constituting the fluororesin composition.

[0010] The present disclosure (5) is a fluororesin composition in which the fluororesin A is polytetrafluoroethylene and any of the present disclosures (1) to (4) is combined.

[0011] The present disclosure (6) is a fluororesin composition in which the fluororesin exhibiting melt fluidity is arbitrarily combined with any of the present disclosures (1) to (5) having a melt flow rate of 0.25 g / 10 min or more.

[0012] The present disclosure (7) is a fluororesin composition in any combination with any of the present disclosures (1) to (6), in which the fluororesin exhibiting melt fluidity is a fluororesin having a melting point of 320°C or less.

[0013] The present disclosure (8) is a fluororesin composition in any combination with any of the present disclosures (1) to (7), in which the fluororesin B is a fluororesin exhibiting melt fluidity, and the fluororesin composition further contains a fluororesin C not exhibiting melt fluidity and having a portion that has no history of being heated to a temperature equal to or higher than the melting point.

[0014] The present disclosure (9) is a fluororesin composition having an apparent density of 0.40 g / ml or more, which is any combination with any of the present disclosures (1) to (8).

[0015] The present disclosure (10) is a fluororesin composition having an angle of repose of less than 40°, which is any combination with any of the present disclosures (1) to (9).

[0016] The present disclosure (11) is a fluororesin composition having an average secondary particle diameter of 5 to 700 μm, which is any combination with any of the present disclosures (1) to (10).

[0017] The present disclosure (12) is a fluororesin composition in any combination with any of the present disclosures (1) to (11), in which the maximum linear length of the particles of fluororesin A is smaller than the maximum linear length of the particles of fluororesin B.

[0018] The present disclosure (13) is a fluororesin composition in any combination with any of the present disclosures (1) to (12), wherein the filler is at least one selected from the group consisting of glass fiber, glass beads, carbon fiber, spherical carbon, carbon black, graphite, silica, alumina, mica, silicon carbide, boron nitride, titanium oxide, bismuth oxide, cobalt oxide, molybdenum disulfide, bronze, gold, silver, copper, and nickel.

[0019] The present disclosure (14) is a fluororesin composition in any combination with any of the present disclosures (1) to (13), in which the filler is a conductive filler.

[0020] The present disclosure (15) is the fluororesin composition according to the present disclosure (14), in which the conductive filler is carbon black.

[0021] The present disclosure (16) is a fluororesin composition in any combination with any of the present disclosures (1) to (15) in powder form.

[0022] The present disclosure (17) is a fluororesin composition in any combination with any of the present disclosures (1) to (16) which are powders for compression molding or powders for ram extrusion molding.

[0023] The present disclosure (18) is a fluororesin composition having a tensile strength at break of 8 MPa or more, which is any combination with any of the present disclosures (1) to (17).

[0024] The present disclosure (19) is a molded article obtained by compression molding and baking or ram extrusion molding a fluororesin composition in any combination with any of the present disclosures (1) to (18).

[0025] The present disclosure (20) is a fluororesin composition having one or more endothermic peaks in the range of 320 to 335°C, which, when thermally decomposed at 600°C under a nitrogen atmosphere, produces a residue of 15% by mass or less relative to the fluororesin composition, and which exhibits electrical conductivity or thermal conductivity of 0.3 W / m K or more.

[0026] The present disclosure (21) further relates to the fluororesin composition of the present disclosure (20), which has one or more endothermic peaks in the range above 335°C.

[0027] The present disclosure (22) is the fluororesin composition of the present disclosure (20) or (21), further comprising an electrically conductive filler or a thermally conductive filler.

[0028] This disclosure (23) is a material having a volume resistivity of 10 4 The fluororesin composition is an arbitrary combination of any of the present disclosures (20) to (22) having a resistivity of Ω·cm or less.

[0029] The present disclosure (24) is a fluororesin composition having an apparent density of 0.40 g / ml or more, which is any combination with any of the present disclosures (20) to (23).

[0030] The present disclosure (25) is a fluororesin composition having an angle of repose of less than 40°, which is any combination with any of the present disclosures (20) to (24).

[0031] The present disclosure (26) is a fluororesin composition in any combination with any of the present disclosures (20) to (25) which are powders for ram extrusion molding.

[0032] The present disclosure (27) is a fluororesin composition having a tensile strength at break of 8 MPa or more, which is any combination with any of the present disclosures (20) to (26).

[0033] The present disclosure (28) is a fluororesin composition in any combination with any of the present disclosures (1) to (18) and (20) to (27) that are not for porous materials. [Effects of the Invention]

[0034] According to the present disclosure, it is possible to provide a fluororesin composition that is excellent in tensile properties and handleability despite containing a fluororesin that has a history of being heated to a temperature equal to or higher than the melting point, and a molded article obtained from the fluororesin composition. DETAILED DESCRIPTION OF THE INVENTION

[0035] The present disclosure will be specifically described below.

[0036] The present disclosure provides a fluororesin composition that does not exhibit melt fluidity (hereinafter also referred to as the first fluororesin composition of the present disclosure), comprising: a fluororesin A that does not exhibit melt fluidity and has a history of being heated to a temperature equal to or higher than its melting point; at least one fluororesin B selected from the group consisting of fluororesins that exhibit melt fluidity and fluororesins that do not exhibit melt fluidity and have no history of being heated to a temperature equal to or higher than its melting point; and a filler. The first fluororesin composition of the present disclosure has the above-described configuration, and therefore has excellent tensile properties (e.g., tensile strength at break, tensile strain at break) and handleability (handleability as a powder) despite containing a fluororesin that has a history of being heated to a temperature equal to or higher than its melting point.

[0037] The fluororesin A has a history of being heated to a temperature equal to or higher than the melting point thereof, for example, for molding, heat treatment, or the like.

[0038] The melting point of the fluororesin A is preferably 100°C or higher and lower than 333°C, more preferably lower than 332°C, and even more preferably lower than 331°C. There is no lower limit, but it is more preferably 140°C, and even more preferably 180°C or higher.

[0039] Fluororesin A preferably has one or more melting points in a temperature range below 333°C. The temperature range below 333°C is more preferably below 332°C, even more preferably below 331°C, and is preferably 100°C or higher, more preferably 140°C or higher, and even more preferably 180°C or higher. The melting point being within the above range indicates that the material has a history of being heated to a temperature equal to or higher than the melting point. The fluororesin A may have a melting point in a temperature range of 333°C or higher.

[0040] In this specification, the melting point of a fluororesin is the temperature corresponding to the minimum point in the heat of fusion curve obtained by differential scanning calorimetry (DSC) at a heating rate of 10°C / min using an X-DSC7000 (manufactured by Hitachi High-Tech Science Corporation). When there are two or more minimum points in one melting peak, each of them is considered to be the melting point.

[0041] Fluorine resin A does not exhibit melt flowability. In this specification, not exhibiting melt flowability means that the melt flow rate (MFR) is less than 0.25 g / 10 min, preferably less than 0.10 g / 10 min, more preferably 0.05 g / 10 min or less. In this specification, MFR is a value obtained in accordance with ASTM D1238 using a melt indexer as the mass of polymer (g / 10 min) flowing out of a nozzle with an inner diameter of 2.095 mm and a length of 8 mm at a measurement temperature determined depending on the type of fluororesin (e.g., 372°C for PFA and FEP, and 297°C for ETFE) and a load (e.g., 5 kg for PFA, FEP, and ETFE). In the case of PTFE, the value is obtained by measurement under the same measurement conditions as for PFA.

[0042] In addition, when a preform (unfired molded body) obtained by compression molding a fluororesin is heated at a temperature equal to or higher than the melting point of the fluororesin for one hour or longer, if the reduction in thickness after heating relative to the thickness before heating is less than 20%, or if the thickness after heating increases compared to the thickness before heating, this also means that the fluororesin does not exhibit melt fluidity.

[0043] Polytetrafluoroethylene [PTFE] is preferred as the fluororesin A. The PTFE may be a high molecular weight PTFE.

[0044] The PTFE as the fluororesin A may be a homopolymer of TFE, or may be a modified PTFE containing 99.0% by mass or more of polymerization units based on TFE and 1.0% by mass or less of polymerization units based on a modifying monomer (hereinafter also referred to as "modified monomer units"). The modified PTFE may consist only of polymerization units based on TFE and modifying monomer units.

[0045] The modified PTFE preferably has a content of the modified monomer unit in the range of 0.00001 to 1.0% by mass relative to the total polymerized units. The lower limit of the content of the modified monomer unit is more preferably 0.0001% by mass, even more preferably 0.001% by mass, even more preferably 0.005% by mass, and especially preferably 0.010% by mass. The upper limit of the content of the modified monomer unit is preferably 0.90% by mass, more preferably 0.50% by mass, even more preferably 0.40% by mass, even more preferably 0.30% by mass, especially preferably 0.20% by mass, and especially preferably 0.10% by mass. In this specification, the modified monomer unit means a part of the molecular structure of PTFE that is derived from the modified monomer.

[0046] The content of each of the above-mentioned polymerized units can be calculated by appropriately combining NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer.

[0047] The modifying monomer is not particularly limited as long as it is copolymerizable with TFE, and examples thereof include perfluoroolefins such as hexafluoropropylene (HFP), hydrogen-containing fluoroolefins such as trifluoroethylene and vinylidene fluoride (VDF), perhaloolefins such as chlorotrifluoroethylene, perfluorovinyl ether, perfluoroallyl ether, (perfluoroalkyl)ethylene, ethylene, etc. The modifying monomer used may be one type or multiple types.

[0048] The perfluorovinyl ether is not particularly limited, and examples thereof include perfluorovinyl ethers represented by the following general formula (A): CF2=CF-ORf (A) (wherein Rf represents a perfluoroorganic group). In this specification, the "perfluoroorganic group" refers to an organic group in which all hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms. The perfluoroorganic group may have an ether oxygen.

[0049] An example of the perfluorovinyl ether is perfluoro(alkyl vinyl ether) [PAVE], where Rf in the 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.

[0050] Examples of the perfluoroalkyl group in the PAVE include a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, and a perfluorohexyl group.

[0051] The perfluorovinyl ether further includes those in which Rf in the general formula (A) is a perfluoro(alkoxyalkyl) group having 4 to 9 carbon atoms, and those in which Rf ...

[0052] [ka]

[0053] (wherein m represents 0 or an integer of 1 to 4), and Rf is a group represented by the following formula:

[0054] [ka]

[0055] (wherein n represents an integer of 1 to 4).

[0056] The (perfluoroalkyl)ethylene (PFAE) is not particularly limited, and examples thereof include (perfluorobutyl)ethylene (PFBE) and (perfluorohexyl)ethylene.

[0057] Examples of perfluoroallyl ethers include those represented by the general formula (B): CF2=CF-CF2-ORf 1 (B) (In the formula, Rf 1 represents a perfluoroorganic group.

[0058] Above Rf 1 is preferably a perfluoroalkyl group having 1 to 10 carbon atoms or a perfluoroalkoxyalkyl group having 1 to 10 carbon atoms. The perfluoroallyl ether is preferably at least one selected from the group consisting of CF2=CF-CF2-O-CF3, CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9, more preferably at least one selected from the group consisting of CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9, and even more preferably CF2=CF-CF2-O-CF2CF2CF3.

[0059] The PTFE used as fluororesin A preferably has a standard specific gravity (SSG) of 2.280 or less, more preferably 2.10 or less, and preferably 1.50 or more, more preferably 1.60 or more. The SSG is measured by the water displacement method according to ASTM D-792 using a sample molded according to ASTM D 4895-89.

[0060] The PTFE used as the fluororesin A generally has non-melt processability. The term "non-melt processability" means that the melt flow rate cannot be measured at a temperature higher than the melting point in accordance with ASTM D-1238 and D-2116, in other words, the PTFE does not flow easily even in the melting temperature range.

[0061] The PTFE (high molecular weight PTFE) used as the fluororesin A preferably has one of its melting points of 310° C. or higher, more preferably 320° C. or higher, and preferably lower than 333° C. It may also have a melting point in the temperature range of 333° C. or higher.

[0062] The first fluororesin composition of the present disclosure may contain particles of fluororesin A. The particles of fluororesin A may be secondary particles of fluororesin A.

[0063] The particles of fluororesin A preferably have an average secondary particle diameter of 1 to 200 μm, more preferably 5 μm or more, even more preferably 10 μm or more, and more preferably 150 μm or less, even more preferably 100 μm or less, even more preferably 70 μm or less, particularly preferably 50 μm or less, and most preferably 30 μm or less. The above average secondary particle diameter is measured using a Beckman Coulter laser diffraction particle size distribution analyzer (LS13 320) in a dry state at a vacuum pressure of 20 mH2O, and is equal to the particle diameter corresponding to 50% of the integrated particle size distribution (volume basis).

[0064] The particles of the fluororesin A preferably have a D90 of 10 μm or more, more preferably 30 μm or more, and even more preferably 50 μm or more, and preferably have a D90 of 600 μm or less, more preferably 500 μm or less, and even more preferably have a D90 of 400 μm or less. The above D90 is measured using a Beckman Coulter laser diffraction particle size analyzer (LS13 320) in a dry state at a vacuum pressure of 20 mH2O, and is equal to the particle diameter corresponding to 90% of the integrated particle size distribution (volume basis).

[0065] The particles of the fluororesin A can be obtained, for example, by compression molding a fluororesin that has no history of being heated to a temperature above its melting point and does not exhibit melt fluidity, followed by calcination and pulverizing the cuttings of the resulting molded product. The pulverization can be carried out using a pulverizer or the like. After coarse pulverization, the pulverized product may be refined. The shape of the compression molded product is not particularly limited. The calcination temperature should be equal to or higher than the melting point of the fluororesin. The pulverizer is not particularly limited as long as it can pulverize (preferably refine) the cuttings. Examples of the pulverizer include an air jet mill, a hammer mill, a force mill, a stone mill-type pulverizer, and a freeze pulverizer.

[0066] The particles of the fluororesin A can also be obtained by heating a powder of a fluororesin that has not been heated to a temperature above its melting point and does not exhibit melt flowability to a temperature above its melting point without compression molding, and then pulverizing the powder using a pulverizer similar to that described above.

[0067] The first fluororesin composition of the present disclosure further contains a filler, which can improve mechanical properties such as abrasion resistance and compressive creep resistance. Examples of the filler include glass fiber, glass beads, carbon fiber, spherical carbon, carbon black, graphite, silica, alumina, mica, silicon carbide, boron nitride, titanium oxide, bismuth oxide, cobalt oxide, molybdenum disulfide, bronze, gold, silver, copper, nickel, aromatic polyester, polyimide, polyphenylene sulfide, and the like, and one or more of these may be used. Among these, at least one selected from the group consisting of glass fiber, carbon fiber, graphite, and bronze is preferred.

[0068] The content of the filler is preferably 0 to 80% by mass relative to the fluororesin composition, more preferably 1% by mass or more, even more preferably 5% by mass or more, even more preferably 10% by mass or more, particularly preferably 12% by mass or more, and more preferably 70% by mass or less, even more preferably 60% by mass or less, even more preferably 50% by mass or less, especially preferably 40% by mass or less, particularly preferably 30% by mass or less, and most preferably 25% by mass or less.

[0069] It is also preferable to use a conductive filler as the filler for the purpose of imparting conductivity to the molded body. When a conductive filler is used as the filler, it has surprisingly been found that the conductivity is improved by using the fluororesin A and fluororesin B in combination as the fluororesin, compared to the case of using only fluororesin B. When fluororesin A is used, gaps tend to form in the molded body, and the conductive filler is filled in to fill these gaps, forming a good conductive path and improving the conductivity.

[0070] Examples of the conductive filler include carbon fillers and metal fillers.

[0071] Examples of the carbon filler include carbon black, graphite, graphene sheets, carbon nanotubes (CNT), PAN-based carbon fibers, and pitch-based carbon fibers, and one or more of these can be used.

[0072] Examples of the metal filler include metal powders of iron, silver, copper, stainless steel, aluminum, nickel, etc., conductive metal oxide powders such as zirconium oxide, metal fibers thereof, conductive metal oxide fibers, and metal-coated synthetic fibers.

[0073] The carbon filler and the metal filler may be used in combination.

[0074] The conductive filler is preferably a carbon filler, and more preferably carbon black. In the first fluororesin composition of the present disclosure, good conductivity can be imparted even when carbon black, which is relatively inexpensive and has excellent handleability, is used.

[0075] The carbon black is preferably conductive carbon black, more preferably at least one selected from the group consisting of acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black, and even more preferably at least one selected from the group consisting of acetylene black, ketjen black, and furnace black.

[0076] The carbon black preferably has an oil absorption of 100 ml / 100 g or more, more preferably 120 ml / 100 g or more, and particularly preferably 150 ml / 100 g or more, since this allows for the production of molded products with even higher conductivity.

[0077] In the first fluororesin composition of the present disclosure, the content of the conductive filler (preferably carbon black) relative to the fluororesin composition is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, particularly preferably 8.0% by mass or less, and also preferably 1.0% by mass or more, more preferably 2.0% by mass or more. As described above, even if the amount of the conductive filler is relatively small, good conductivity can be imparted, and therefore conductivity can be imparted without impairing the molding processability or the mechanical strength of the molded body.

[0078] The conductive filler such as CNT has an aspect ratio of 1000 or more, which facilitates the formation of a good conductive network, and therefore the blending amount can be further reduced. The content of the conductive filler having an aspect ratio of 1000 or more is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less, particularly preferably 1% by mass or less, and also preferably 0.0001% by mass or more, more preferably 0.001% by mass or more, and even more preferably 0.01% by mass or more, relative to the fluororesin composition.

[0079] In addition to the conductive filler, a non-conductive filler may be used in combination within a range that does not impair performance. Examples of the non-conductive filler include non-conductive inorganic oxide fillers such as silica, silicate, clay, diatomaceous earth, montmorillonite, talc, calcium carbonate, calcium silicate, barium sulfate, fatty acid calcium, titanium oxide, red iron oxide, boron nitride, aluminum nitride, magnesium oxide, and alumina, and non-conductive resin fillers such as polyimide.

[0080] It is also preferable to use a thermally conductive filler as the filler for the purpose of imparting thermal conductivity to the molded article. When a thermally conductive filler is used as the filler, it has surprisingly been found that the combined use of fluororesin A and fluororesin B as the fluororesins improves thermal conductivity compared to the use of fluororesin B alone. When fluororesin A is used, the filler does not enter into fluororesin A, so the thermally conductive filler is filled around fluororesin A, forming a good thermal conduction path and improving thermal conductivity.

[0081] Examples of the thermally conductive filler include boron nitride, aluminum nitride, magnesium oxide, and alumina, and one or more of these can be used.

[0082] The thermally conductive filler is preferably boron nitride, which can impart good thermal conductivity to the first fluororesin composition of the present disclosure.

[0083] In the first fluororesin composition of the present disclosure, the content of the thermally conductive filler (preferably boron nitride) relative to the fluororesin composition is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, particularly preferably 8.0% by mass or less, and is preferably 1.0% by mass or more, more preferably 2.0% by mass or more. As described above, even if the amount of the thermally conductive filler is relatively small, good thermal conductivity can be imparted, and therefore thermal conductivity can be imparted without impairing the molding processability or the mechanical strength of the molded body.

[0084] The first fluororesin composition of the present disclosure further comprises at least one fluororesin B selected from the group consisting of fluororesins exhibiting melt fluidity and fluororesins not exhibiting melt fluidity and having no history of being heated to a temperature equal to or higher than their melting point. By including the fluororesin B, the tensile properties are improved compared to when only the fluororesin A and the filler are used.

[0085] In one preferred embodiment, the fluororesin B is a fluororesin that exhibits melt fluidity. The fluororesin exhibiting melt fluidity may have an MFR of 0.25 g / 10 min or more, preferably 0.50 g / 10 min or more, more preferably 1.00 g / 10 min or more, and may have an MFR of 100 g / 10 min or less, preferably 80 g / 10 min or less.

[0086] The fluororesin exhibiting melt fluidity is preferably at least one selected from the group consisting of fluororesin having a melting point of 320°C or less and low-molecular-weight polytetrafluoroethylene (low-molecular-weight PTFE), and more preferably a fluororesin having a melting point of 320°C or less. The fluororesin exhibiting melt fluidity will be described in detail later.

[0087] When the fluororesin B is a fluororesin exhibiting melt fluidity, the first fluororesin composition of the present disclosure preferably further contains a fluororesin C that does not exhibit melt fluidity and has a portion that has not been heated to a temperature equal to or higher than its melting point. By further containing the fluororesin C, the tensile properties are further improved. The fluororesin C will be described in detail later.

[0088] In one preferred embodiment, the fluororesin B is a fluororesin that does not exhibit melt fluidity and has no history of being heated to a temperature equal to or higher than its melting point. The fluororesin that does not exhibit melt fluidity and has no history of being heated to a temperature equal to or higher than its melting point may be one that has been polymerized by suspension polymerization or emulsion polymerization. PTFE is preferred as the fluororesin that has no history of being heated to a temperature equal to or higher than the melting point and does not exhibit melt fluidity. The PTFE may be a homopolymer of TFE, or a modified PTFE containing 99.0% by mass or more of polymerized units based on TFE and 1.0% by mass or less of polymerized units based on a modified monomer (modified monomer units). The fluororesin that does not exhibit melt fluidity and has no history of being heated to a temperature equal to or higher than the melting point will be described in detail later.

[0089] The content of fluororesin A in the first fluororesin composition of the present disclosure is preferably 10 to 99.5% by mass relative to the fluororesin composition, in order to further improve tensile properties. The content is more preferably 30% by mass or more, even more preferably 40% by mass or more, and particularly preferably 50% by mass or more, and is more preferably 99% by mass or less, even more preferably 95% by mass or less, even more preferably 90% by mass or less, especially preferably 85% by mass or less, and particularly preferably 80% by mass or less.

[0090] When fluororesin B in the first fluororesin composition of the present disclosure is a fluororesin exhibiting melt fluidity, its content is preferably 0.5 to 30% by mass relative to the fluororesin composition, in order to further improve tensile properties. The content is more preferably 1.0% by mass or more, even more preferably 3% by mass or more, even more preferably 5% by mass or more, and particularly preferably 7% by mass or more, and is more preferably 25% by mass or less, even more preferably 20% by mass or less, even more preferably 15% by mass or less, and particularly preferably 10% by mass or less.

[0091] When fluororesin B in the first fluororesin composition of the present disclosure is a fluororesin that has no history of being heated to a temperature equal to or higher than its melting point and does not exhibit melt fluidity, the content of the fluororesin B relative to the fluororesin composition is preferably 10 to 90% by mass, in order to further improve tensile properties. The content is more preferably 15% by mass or more, even more preferably 20% by mass or more, even more preferably more than 20% by mass, especially preferably 25% by mass or more, and particularly preferably 30% by mass or more, and more preferably 80% by mass or less, even more preferably 70% by mass or less, even more preferably 60% by mass or less, and particularly preferably 50% by mass or less.

[0092] The content of fluororesin C in the first fluororesin composition of the present disclosure is preferably 0 to 80% by mass relative to the fluororesin composition, in order to further improve tensile properties. The content is more preferably 1% by mass or more, even more preferably 10% by mass or more, even more preferably 20% by mass or more, especially preferably 30% by mass or more, and particularly preferably 40% by mass or more, and is more preferably 75% by mass or less, even more preferably 70% by mass or less, even more preferably 65% ​​by mass or less, especially preferably 60% by mass or less, and particularly preferably 50% by mass or less.

[0093] The total amount of fluororesins A to C in the first fluororesin composition of the present disclosure is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 98% by mass or more, relative to the fluororesin composition.

[0094] The first fluororesin composition of the present disclosure does not exhibit melt flowability. The MFR of the first fluororesin composition of the present disclosure may be less than 0.25 g / 10 min, preferably less than 0.10 g / 10 min, and more preferably 0.05 g / 10 min or less.

[0095] Furthermore, when a preform (unfired molded body) obtained by compression molding the first fluororesin composition of the present disclosure is heated at a temperature equal to or higher than the melting point of the fluororesin composition for 1 hour or longer, it is preferable that the reduction in thickness after heating relative to the thickness before heating is less than 20% or that the thickness after heating increases compared to the thickness before heating, since these also mean that the fluororesin composition does not exhibit melt flowability.

[0096] The first fluororesin composition of the present disclosure preferably has one or more melting points in a temperature range below 333°C and one or more melting points in a temperature range of 333 to 360°C. The temperature range of less than 333°C is more preferably less than 332°C, even more preferably less than 331°C, and is preferably 100°C or higher, more preferably 140°C or higher, and even more preferably 160°C or higher. The temperature range of 333 to 360°C is more preferably 334°C or higher, even more preferably 335°C, and is more preferably 355°C or lower, even more preferably 350°C or lower. Having melting points in the above two temperature ranges means that the fluororesin composition contains a fluororesin that does not exhibit melt flowability and has a history of being heated to a temperature equal to or higher than its melting point, and a fluororesin that does not exhibit melt flowability and has no history of being heated to a temperature equal to or higher than its melting point.

[0097] The first fluororesin composition of the present disclosure preferably contains TFE units and modified monomer units based on a modified monomer copolymerizable with TFE. The fluororesin composition may contain only TFE units and modified monomer units as polymerization units.

[0098] In order to further improve handleability and tensile properties, the content of the modified monomer unit is preferably 1.0 mass% or less based on the total polymerized units constituting the fluororesin composition. The lower limit of the content of the modified monomer unit is preferably 0.00001 mass%, more preferably 0.0001 mass%, even more preferably 0.001 mass%, even more preferably 0.005 mass%, and especially preferably 0.010 mass%. The upper limit of the content of the modified monomer unit is preferably 0.90 mass%, more preferably 0.50 mass%, even more preferably 0.40 mass%, even more preferably 0.30 mass%, even more preferably 0.20 mass%, and especially preferably 0.10 mass%.

[0099] The first fluororesin composition of the present disclosure preferably contains 99.0 mass % or more of TFE units based on all polymerized units.

[0100] The content of the polymerized units constituting the first fluororesin composition of the present disclosure can be calculated by an appropriate combination of NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer. Alternatively, if the raw material composition is known, the content can be calculated from the raw material composition.

[0101] In order to achieve even better handleability, the first fluororesin composition of the present disclosure preferably has an apparent density of 0.40 g / ml or more, more preferably 0.42 g / ml or more, even more preferably 0.45 g / ml or more, and particularly preferably 0.47 g / ml or more. There is no particular upper limit, but it may be 1.00 g / ml. The apparent density is measured in accordance with JIS K 6891.

[0102] The first fluororesin composition of the present disclosure preferably has an angle of repose of less than 40°, more preferably less than 38°, and even more preferably less than 35°, in view of excellent fluidity and even better handleability. The above angle of repose is a value obtained by placing a funnel with a total height of 115 mm, a foot diameter of φ26 mm, a foot length of 35 mm, and an intake opening of 60° so that the height from the bottom of the funnel to the sample drop surface is 100 mm, dropping 40 g of sample from the funnel, and measuring the angle of the lower half of the peak of the dropped sample with a protractor.

[0103] The first fluororesin composition of the present disclosure preferably has an average secondary particle diameter of 5 to 700 μm, more preferably 10 μm or more, and even more preferably 20 μm or more, and more preferably 600 μm or less, even more preferably 500 μm or less, and particularly preferably 400 μm or less. The above average secondary particle diameter is measured using a Beckman Coulter laser diffraction particle size distribution analyzer (LS13 320) in a dry state at a vacuum pressure of 20 mH2O, and is equal to the particle diameter corresponding to 50% of the integrated particle size distribution (volume basis).

[0104] In the first fluororesin composition of the present disclosure, the maximum linear length of the particles of fluororesin A is preferably smaller than the maximum linear length of the particles of fluororesin B. When the maximum linear lengths of the particles of fluororesins A and B satisfy the above relationship, the apparent density of the fluororesin composition can be increased, further improving handleability. In addition, since there is no need to perform a deformation treatment to increase the maximum linear length of the particles of fluororesin A, the production cost of the fluororesin composition can be reduced.

[0105] The form of the first fluororesin composition of the present disclosure is not particularly limited, but is preferably a powder.

[0106] The first fluororesin composition of the present disclosure is preferably a fluororesin composition that does not exhibit melt fluidity (also referred to as fluororesin composition (1)) that contains a fluororesin A that does not exhibit melt fluidity and has a history of being heated to a temperature equal to or higher than its melting point, a fluororesin B1 that exhibits melt fluidity, and a filler. The fluororesin composition (1) contains a fluororesin B1 that exhibits melt flowability, and therefore has excellent tensile properties (e.g., tensile strength and strain at break) despite containing a fluororesin A that has been heated to a temperature above its melting point. This effect is thought to be due to the fact that the interfaces between particles of the fluororesin A are filled with the fluororesin B1 during molding.

[0107] In the fluororesin composition (1), a method for distinguishing between the fluororesin A and the fluororesin B1 includes, for example, placing the fluororesin composition on a hot stage, observing it under a microscope while raising the temperature at a rate of 5°C / min, and determining whether the particles are of fluororesin A or B1 based on whether the particle shape is maintained.

[0108] As the fluororesin A and the filler in the fluororesin composition (1), those mentioned above can be used.

[0109] The fluororesin B1 exhibits melt fluidity. In this specification, "exhibiting melt fluidity" means that the MFR is 0.25 g / 10 min or more, preferably 0.50 g / 10 min or more, and more preferably 1.00 g / 10 min or more. The MFR may be 100 g / 10 min or less, and preferably 80 g / 10 min or less.

[0110] In addition, when a preform (unfired molded body) obtained by compression molding a fluororesin is heated at a temperature equal to or higher than the melting point of the fluororesin for one hour or more, the reduction in thickness after heating relative to the thickness before heating of 20% or more also means that the fluororesin exhibits melt fluidity.

[0111] The fluororesin B1 preferably has no history of being heated to a temperature equal to or higher than its melting point.

[0112] The fluororesin B1 preferably has a melting point of 100 to 340° C. The melting point is more preferably 140° C. or higher, even more preferably 160° C. or higher, and more preferably 336° C. or lower, even more preferably 333° C. or lower, even more preferably 332° C. or lower, particularly preferably 331° C. or lower, and particularly preferably 330° C. or lower.

[0113] The melting point of fluororesin B1 can be measured by the method described above, but when the amount of fluororesin B1 is small, for example, 5% by mass or less, relative to the total amount of fluororesin A and fluororesin B1, it may be difficult to detect using the method described above. In this case, the melting peak of fluororesin B1 may be detected by holding the sample at a temperature lower than the melting point of fluororesin B1 (preferably at a temperature 10°C or more lower than the melting point) for 10 minutes during heating, and then heating it again at a rate of 10°C / min. This method of heating may also be used.

[0114] The fluororesin B1 is preferably at least one selected from the group consisting of fluororesins having a melting point of 320°C or less and low-molecular-weight polytetrafluoroethylene (low-molecular-weight PTFE), and more preferably a fluororesin having a melting point of 320°C or less. The fluororesin B1 is also preferably a perfluororesin.

[0115] Examples of the fluororesin having a melting point of 320°C or less include tetrafluoroethylene [TFE] / perfluoro(alkyl vinyl ether) [PAVE] or perfluoro(alkyl allyl ether) copolymer [PFA], TFE / hexafluoropropylene [HFP] copolymer [FEP], ethylene [Et] / TFE copolymer [ETFE], Et / TFE / HFP copolymer [EFEP], polychlorotrifluoroethylene [PCTFE], chlorotrifluoroethylene [CTFE] / TFE copolymer, CTFE / TFE / PAVE copolymer, and Et / CTFE copolymer. Examples of the polymer include a polymer, polyvinyl fluoride [PVF], polyvinylidene fluoride [PVdF], vinylidene fluoride [VdF] / TFE copolymer, VdF / HFP copolymer, VdF / TFE / HFP copolymer, VdF / HFP / (meth)acrylic acid copolymer, VdF / CTFE copolymer, VdF / pentafluoropropylene copolymer, and VdF / PAVE / TFE copolymer. At least one selected from the group consisting of PFA, FEP, and ETFE is preferred, at least one selected from the group consisting of PFA and FEP is more preferred, and PFA is even more preferred.

[0116] The PFA contains a TFE unit and a PAVE unit or a perfluoro(alkylaryl ether) unit. The PAVE includes a monomer in which Rf in the general formula (A) is a perfluoroalkyl group having 1 to 10 carbon atoms. The perfluoro(alkylaryl ether) includes a monomer in which Rf in the general formula (B) is a perfluoroalkyl group having 1 to 10 carbon atoms. 1 is a perfluoroalkyl group having 1 to 10 carbon atoms.

[0117] The PFA is not particularly limited, but is preferably a copolymer in which the molar ratio of TFE units to PAVE units or perfluoro(alkyl allyl ether) units (TFE units / (PAVE units or perfluoro(alkyl allyl ether) units)) is 70 / 30 or more and less than 99 / 1. A more preferred molar ratio is 70 / 30 or more and 98.9 / 1.1 or less, and an even more preferred molar ratio is 80 / 20 or more and 98.9 / 1.1 or less. The PFA is also preferably a copolymer in which polymerization units derived from monomers copolymerizable with TFE and PAVE or perfluoro(alkyl allyl ether) account for 0.1 to 10 mol % (90 to 99.9 mol % in total of TFE units and PAVE units or perfluoro(alkyl allyl ether) units), more preferably 0.1 to 5 mol %, and particularly preferably 0.2 to 4 mol %.

[0118] Monomers copolymerizable with TFE and PAVE or perfluoro(alkyl allyl ether) include HFP, a copolymer of formula (I): CZ 1 Z 2 =CZ 3 (CF2) n Z 4 (In the formula, Z 1 , Z 2 and Z 3 are the same or different and represent a hydrogen atom or a fluorine atom; Z 4 represents a hydrogen atom, a fluorine atom or a chlorine atom, and n represents an integer of 2 to 10.) and a vinyl monomer represented by formula (II): CF2=CF-OCH2-Rf 2 (In the formula, Rf 2 represents a perfluoroalkyl group having 1 to 5 carbon atoms, an alkyl perfluorovinyl ether derivative represented by formula (III): CZ 5 Z 6 =CZ 7 -CZ 8 Z 9 -O-Rf 3 (in the formula, in the formula, Z 5 , Z 6 and Z 7 are the same or different and represent a hydrogen atom, a chlorine atom or a fluorine atom; Z 8 and Z 9represents a hydrogen atom or a fluorine atom, and Rf 3 represents a perfluoroalkyl group having 1 to 5 carbon atoms. Examples of the allyl ether monomer include an allyl ether monomer represented by CH2=CFCF2-O-Rf 3 , CF2=CFCH2-O-Rf 3 , CH2=CHCF2-O-Rf 3 (In the formula, Rf 3 is the same as the above formula (III). Further examples of the monomer copolymerizable with TFE and PAVE or perfluoro(alkyl allyl ether) include unsaturated monocarboxylic acids, unsaturated dicarboxylic acids, and acid anhydrides of unsaturated dicarboxylic acids, such as itaconic acid, itaconic anhydride, citraconic anhydride, and 5-norbornene-2,3-dicarboxylic anhydride.

[0119] The melting point of the PFA is preferably 180 to 320°C, more preferably 230 to 320°C, and even more preferably 280 to 320°C.

[0120] The PFA preferably has an MFR of 0.25 g / 10 min or more and 100 g / 10 min or less, more preferably 0.5 g / 10 min or more, and even more preferably 1.0 g / 10 min or more, and more preferably 90 g / 10 min or less, and even more preferably 80 g / 10 min or less. The MFR of PFA is a value obtained in accordance with ASTM D1238 using a melt indexer, as the mass of polymer flowing out per 10 minutes (g / 10 minutes) from a nozzle with an inner diameter of 2.095 mm and a length of 8 mm at a measurement temperature of 372°C and a load of 5 kg.

[0121] The FEP is not particularly limited, but is preferably a copolymer in which the molar ratio of TFE units to HFP units (TFE units / HFP units) is 70 / 30 or more and less than 99 / 1. A more preferred molar ratio is 70 / 30 or more and 98.9 / 1.1 or less, and an even more preferred molar ratio is 80 / 20 or more and 98.9 / 1.1 or less. The FEP is also preferably a copolymer in which the polymerized units derived from monomers copolymerizable with TFE and HFP account for 0.1 to 10 mol % (90 to 99.9 mol % in total of TFE units and HFP units), more preferably 0.1 to 5 mol %, and particularly preferably 0.2 to 4 mol %.

[0122] Examples of the monomer copolymerizable with TFE and HFP include PAVE, a monomer represented by formula (III), and an alkyl perfluorovinyl ether derivative represented by formula (II). Further examples of the monomer copolymerizable with TFE and HFP include unsaturated monocarboxylic acids, unsaturated dicarboxylic acids, and acid anhydrides of unsaturated dicarboxylic acids, such as itaconic acid, itaconic anhydride, citraconic anhydride, and 5-norbornene-2,3-dicarboxylic anhydride.

[0123] The melting point of the FEP is preferably 150 to 320°C, more preferably 200 to 320°C, and even more preferably 240 to 320°C.

[0124] The FEP preferably has an MFR of 0.25 g / 10 min or more and 100 g / 10 min or less, more preferably 0.5 g / 10 min or more, and even more preferably 1.0 g / 10 min or more, and more preferably 80 g / 10 min or less, and even more preferably 60 g / 10 min or less. The MFR of FEP is a value obtained in accordance with ASTM D1238 using a melt indexer, and is the mass of polymer (g / 10 min) flowing out of a nozzle with an inner diameter of 2.095 mm and a length of 8 mm at a measurement temperature of 372°C and a load of 5 kg per 10 min.

[0125] The ETFE is preferably a copolymer having a molar ratio of TFE units to ethylene units (TFE units / ethylene units) of 20 / 80 or more and 90 / 10 or less. A more preferred molar ratio is 37 / 63 or more and 85 / 15 or less, and an even more preferred molar ratio is 38 / 62 or more and 80 / 20 or less. The ETFE may be a copolymer consisting of TFE, ethylene, and a monomer copolymerizable with TFE and ethylene. The copolymerizable monomer may be a copolymer represented by the following formula: CH2=CX 1 Rf 4 , CF2=CFRf 4 , CF2=CFORf 4 , CH2=C(Rf 4 )2(where, X 1 is a hydrogen atom or a fluorine atom, Rf 4 represents a fluoroalkyl group which may contain an ether bond.) and a monomer represented by formula (III), among which CF2=CFRf 4 , CF2=CFORf 4 and CH2=CX 1 Rf 4 and a monomer represented by formula (III) are preferred, and HFP, CF2=CF-ORf 5 (In the formula, Rf 5 represents a perfluoroalkyl group having 1 to 5 carbon atoms.) 3 (In the formula, Rf 3 represents a perfluoroalkyl group having 1 to 5 carbon atoms. 4 is a fluoroalkyl group having 1 to 8 carbon atoms, CH2=CX 1 Rf 4 The monomer copolymerizable with TFE and ethylene may be an aliphatic unsaturated carboxylic acid such as itaconic acid or itaconic anhydride. The amount of the monomer copolymerizable with TFE and ethylene is preferably 0.1 to 10 mol %, more preferably 0.1 to 5 mol %, and particularly preferably 0.2 to 4 mol %, based on the fluorine-containing polymer.

[0126] The melting point of the ETFE is preferably 140 to 320°C, more preferably 160 to 320°C, and even more preferably 195 to 320°C.

[0127] The ETFE preferably has an MFR of 0.25 g / 10 min or more and 100 g / 10 min or less, more preferably 0.5 g / 10 min or more, and even more preferably 1.0 g / 10 min or more, and more preferably 90 g / 10 min or less, and even more preferably 80 g / 10 min or less. The MFR of ETFE is a value obtained in accordance with ASTM D1238 using a melt indexer, and is the mass (g / 10 min) of polymer flowing out per 10 min from a nozzle with an inner diameter of 2.095 mm and a length of 8 mm at a measurement temperature of 297°C and a load of 5 kg.

[0128] The above low molecular weight PTFE has a melt viscosity (complex viscosity) of 1.0 × 10 at 380 °C. 1 ~1.0×10 7 It is preferably Pa·s. The melt viscosity is 1.0 x 10 2 Pa·s or more is more preferable, and 1.5×10 3 Pa·s or more is more preferable, and 7.0×10 3 It is particularly preferable that the viscosity is 7.0×10 Pa·s or more. 5 Pa·s or less is more preferable, and 3.0×10 5 Pa·s or less is more preferable, and 1.0×10 5 It is particularly preferable that the viscosity is not more than Pa·s. In this specification, "low molecular weight PTFE" means PTFE having the melt viscosity within the above range.

[0129] The melt viscosity was measured in accordance with ASTM D 1238 using a flow tester (manufactured by Shimadzu Corporation) and a 2φ-8L die, with a 2g sample preheated at 380°C for 5 minutes and maintained at the temperature under a load of 0.7 MPa.

[0130] The low-molecular-weight PTFE preferably has an MFR (mass of polymer flowing per 10 minutes (g / 10 min) from a nozzle with an inner diameter of 2.095 mm and a length of 8 mm at 372°C under a load of 5 kg) of 0.25 g / 10 min or more, more preferably 0.10 g / 10 min or more, and even more preferably 0.05 g / 10 min or more. The MFR is also preferably 50 g / 10 min or less, more preferably 30 g / 10 min or less, and even more preferably 10 g / 10 min or less.

[0131] The low-molecular-weight PTFE preferably has a melting point of 320 to 340° C. The melting point is more preferably 324° C. or higher, more preferably 336° C. or lower, even more preferably 333° C. or lower, even more preferably 332° C. or lower, particularly preferably 331° C. or lower, and particularly preferably 330° C. or lower.

[0132] The low-molecular-weight PTFE may be a homopolymer of TFE, or may be a modified PTFE containing 99.0% by mass or more of polymerization units based on TFE and 1.0% by mass or less of polymerization units based on a modifying monomer (hereinafter also referred to as "modified monomer units"). The modified PTFE may consist only of polymerization units based on TFE and modifying monomer units.

[0133] The modified PTFE preferably has a content of the modified monomer unit in the range of 0.00001 to 1.0% by mass relative to the total polymerized units. The lower limit of the content of the modified monomer unit is more preferably 0.0001% by mass, even more preferably 0.001% by mass, even more preferably 0.005% by mass, and especially preferably 0.010% by mass. The upper limit of the content of the modified monomer unit is preferably 0.90% by mass, more preferably 0.50% by mass, even more preferably 0.40% by mass, even more preferably 0.30% by mass, especially preferably 0.20% by mass, and especially preferably 0.10% by mass.

[0134] The modifying monomer may be the monomer described above for PTFE (high molecular weight PTFE) as a fluororesin that does not exhibit melt flowability.

[0135] The content of each polymer unit in the above-mentioned polymer can be calculated by appropriately combining NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer.

[0136] The fluororesin B1 can be produced by a known polymerization method such as emulsion polymerization, suspension polymerization, or solution polymerization.

[0137] The fluororesin composition (1) may contain particles of the fluororesin B1. The particles of the fluororesin B1 may be primary particles or secondary particles of the fluororesin B1.

[0138] When the particles of the fluororesin B1 are primary particles (in the state of an aqueous dispersion), the average primary particle diameter is preferably 500 nm or less. The average primary particle diameter is more preferably 400 nm or less, and even more preferably 300 nm or less. The average primary particle diameter is also preferably 10 nm or more, more preferably 25 nm or more, even more preferably 50 nm or more, even more preferably 100 nm or more, and particularly preferably 150 nm or more. The above average primary particle diameter is the average diameter of 100 or more particles randomly sampled by dropping an aqueous dispersion with a solid content adjusted to 0.5% by mass onto aluminum foil, drying the resulting mixture at 150°C for 1 hour to remove water, and observing the resulting mixture with a scanning electron microscope (SEM).

[0139] When the particles of the fluororesin B1 are secondary particles (in a powder state), the average secondary particle diameter is preferably 100 μm or less. The average secondary particle diameter is more preferably 70 μm or less, even more preferably 50 μm or less, and particularly preferably 40 μm or less. The average secondary particle diameter is also preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and even more preferably 20 μm or more. The above average secondary particle diameter is measured using a Beckman Coulter laser diffraction particle size distribution analyzer (LS13 320) in a dry state at a vacuum pressure of 20 mH2O, and is equal to the particle diameter corresponding to 50% of the integrated particle size distribution (volume basis).

[0140] The fluororesin composition (1) preferably further contains a fluororesin C that does not exhibit melt fluidity and has a portion that has not been heated to a temperature equal to or higher than its melting point. Although the fluororesin composition (1) has excellent tensile properties even without the fluororesin C, the tensile properties are further improved by further containing the fluororesin C. The fluororesin composition (1) preferably contains fluororesins A and B, and optionally a fluororesin C.

[0141] Fluororesin C has a portion that has no history of being heated to a temperature equal to or higher than the melting point. The fluororesin C preferably has one or more melting points in the temperature range of 333 to 360° C. The temperature range is more preferably 334° C. or higher, and even more preferably 335° C. or higher, and is more preferably 355° C. or lower, and even more preferably 350° C. or lower. The melting point being within the above range indicates that the material has a portion that has no history of being heated to a temperature equal to or higher than the melting point. In addition to the above melting point, the polymer may also have a melting point in a temperature range below 333°C.

[0142] When the fluororesin composition (1) further contains the fluororesin C, it preferably has one or more melting points in a temperature range below 333°C and one or more melting points in a temperature range of 333 to 360°C. The temperature range of less than 333°C is more preferably less than 332°C, even more preferably less than 331°C, and is preferably 100°C or higher, more preferably 140°C or higher, and even more preferably 160°C or higher. The temperature range of 333 to 360°C is more preferably 334°C or higher, even more preferably 335°C, and is more preferably 355°C or lower, even more preferably 350°C or lower. Having melting points in the above two temperature ranges means that the fluororesin composition contains fluororesin A, which has a history of being heated to a temperature equal to or higher than its melting point and does not exhibit melt fluidity, and fluororesin C, which has a portion that has not a history of being heated to a temperature equal to or higher than its melting point and does not exhibit melt fluidity.

[0143] Fluororesin C does not exhibit melt fluidity, as described above.

[0144] PTFE is preferred as the fluororesin C. The PTFE may be a high molecular weight PTFE.

[0145] The PTFE (high molecular weight PTFE) as fluororesin C preferably exhibits at least one endothermic peak in the range of 333 to 347°C in a heat of fusion curve when heated at a rate of 10°C / min using a differential scanning calorimeter (DSC), and has a heat of fusion of 62 mJ / mg or more in the range of 290 to 350°C calculated from the heat of fusion curve.

[0146] The PTFE as the fluororesin C preferably has a standard specific gravity (SSG) of 2.130 to 2.280. The standard specific gravity is measured by a water displacement method in accordance with ASTM D 792 using a sample molded in accordance with ASTM D4895 89. The term "high molecular weight" for PTFE that has not been heated to a temperature equal to or higher than its melting point means that the standard specific gravity is within the above range.

[0147] The PTFE as the fluororesin C generally has non-melt secondary processability, as described above.

[0148] The PTFE as the fluororesin C may be a homopolymer of TFE, or may be a modified PTFE containing 99.0% by mass or more of polymerization units based on TFE and 1.0% by mass or less of polymerization units based on a modifying monomer (modifying monomer units). The modified PTFE may consist only of polymerization units based on TFE and modifying monomer units.

[0149] The modified PTFE preferably has a content of the modified monomer unit in the range of 0.00001 to 1.0% by mass relative to the total polymerized units. The lower limit of the content of the modified monomer unit is more preferably 0.0001% by mass, even more preferably 0.001% by mass, even more preferably 0.005% by mass, and especially preferably 0.010% by mass. The upper limit of the content of the modified monomer unit is preferably 0.90% by mass, more preferably 0.50% by mass, even more preferably 0.40% by mass, even more preferably 0.30% by mass, especially preferably 0.20% by mass, and especially preferably 0.10% by mass.

[0150] The modifying monomers that can be used in the above PTFE as the fluororesin C are the same as those exemplified for the PTFE (high molecular weight PTFE) as the fluororesin A.

[0151] The fluororesin composition (1) may contain particles of the fluororesin C. The particles of the fluororesin C may be primary particles of the fluororesin C or secondary particles.

[0152] When the particles of the fluororesin C are primary particles (in the state of an aqueous dispersion), the average primary particle diameter is preferably 500 nm or less. The average primary particle diameter is more preferably 400 nm or less, even more preferably 350 nm or less, and particularly preferably 300 nm or less. The average primary particle diameter is also preferably 10 nm or more, more preferably 25 nm or more, even more preferably 50 nm or more, even more preferably 100 nm or more, and particularly preferably 150 nm or more. The above average primary particle diameter is the average diameter of 100 or more particles randomly sampled by dropping an aqueous dispersion with a solid content adjusted to 0.5% by mass onto aluminum foil, drying the resulting mixture at 150°C for 1 hour to remove water, and observing the resulting mixture with a scanning electron microscope (SEM).

[0153] When the particles of the fluororesin C are secondary particles (in a powder state), the average secondary particle diameter is preferably 700 μm or less. The average secondary particle diameter is more preferably 500 μm or less, even more preferably 100 μm or less, even more preferably 60 μm or less, and particularly preferably 50 μm or less. The average secondary particle diameter is also preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and even more preferably 20 μm or more. The above average secondary particle diameter is measured using a Beckman Coulter laser diffraction particle size distribution analyzer (LS13 320) in a dry state at a vacuum pressure of 20 mH2O, and is equal to the particle diameter corresponding to 50% of the integrated particle size distribution (volume basis).

[0154] In one embodiment of the fluororesin composition (1), when the particles of the fluororesin C exist in the state of primary particles, the average aspect ratio is preferably 2.0 or less, more preferably 1.7 or less, even more preferably 1.6 or less, even more preferably 1.5 or less, particularly preferably 1.4 or less, and particularly preferably 1.3 or less. The average aspect ratio may also be 1.0 or more.

[0155] The average aspect ratio is determined by observing the fluororesin composition with a scanning electron microscope (SEM), processing the images of 100 or more randomly selected primary particles, and averaging the ratio of their major axis to their minor axis.

[0156] In another embodiment of the fluororesin composition (1), when the particles of the fluororesin C exist in the state of primary particles, the proportion of the particles of the fluororesin C having an aspect ratio of 2.5 or more relative to the total number of particles of the fluororesin C is preferably 0.5% or more, more preferably 1.0% or more, even more preferably 1.5% or more, and particularly preferably 2.0% or more. The proportion is also preferably 20% or less, more preferably 15% or less, and even more preferably 10% or less.

[0157] The above ratio is determined by observing the fluororesin composition with a scanning electron microscope (SEM), randomly sampling 100 or more primary particles, processing the images of the particles, calculating the aspect ratio of each particle, and expressing the ratio as a percentage of the total number of the particles sampled.

[0158] The content of fluororesin A in fluororesin composition (1) is preferably 10 to 99.5% by mass relative to the fluororesin composition, in order to further improve tensile properties. The content is more preferably 30% by mass or more, even more preferably 40% by mass or more, and particularly preferably 50% by mass or more, and is more preferably 99% by mass or less, even more preferably 95% by mass or less, even more preferably 90% by mass or less, especially preferably 85% by mass or less, and particularly preferably 80% by mass or less.

[0159] The content of fluororesin B1 in fluororesin composition (1) is preferably 0.5 to 30% by mass relative to the fluororesin composition in order to further improve tensile properties. The content is more preferably 1.0% by mass or more, even more preferably 3% by mass or more, even more preferably 5% by mass or more, particularly preferably 7% by mass or more, and more preferably 25% by mass or less, even more preferably 20% by mass or less, even more preferably 15% by mass or less, particularly preferably 10% by mass or less.

[0160] The content of fluororesin C in fluororesin composition (1) is preferably 0 to 80% by mass relative to the fluororesin composition, in order to further improve tensile properties. The content is more preferably 1% by mass or more, even more preferably 10% by mass or more, even more preferably 20% by mass or more, especially preferably 30% by mass or more, and particularly preferably 40% by mass or more, and is more preferably 75% by mass or less, even more preferably 70% by mass or less, even more preferably 65% ​​by mass or less, especially preferably 60% by mass or less, and particularly preferably 50% by mass or less.

[0161] The total amount of fluororesins A to C in the fluororesin composition (1) is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 98% by mass or more, based on the fluororesin composition.

[0162] The fluororesin composition (1) does not exhibit melt fluidity. The MFR of the fluororesin composition (1) may be less than 0.25 g / 10 min, preferably less than 0.10 g / 10 min, and more preferably 0.05 g / 10 min or less.

[0163] Furthermore, when a preform (unfired molded body) obtained by compression molding the fluororesin composition (1) is heated at a temperature equal to or higher than the melting point of the fluororesin composition for 1 hour or longer, it is preferable that the reduction rate of the thickness after heating relative to the thickness before heating is less than 20% or that the thickness after heating increases compared to the thickness before heating, since this also means that the fluororesin composition does not exhibit melt flowability.

[0164] The fluororesin composition (1) contains TFE units and modified monomer units derived from a modified monomer copolymerizable with TFE, and the amount of the modified monomer units is preferably 1.0 mass% or less relative to the total polymerized units, and the amount of TFE units is preferably 99.0 mass% or more.

[0165] The lower limit of the content of the modified monomer unit in the fluororesin composition (1) may be 0% by mass, more preferably 0.0001% by mass, even more preferably 0.001% by mass, even more preferably 0.005% by mass, and particularly preferably 0.010% by mass. The upper limit of the content of the modified monomer unit is preferably 0.90% by mass, more preferably 0.50% by mass, even more preferably 0.40% by mass, even more preferably 0.30% by mass, especially preferably 0.20% by mass, and particularly preferably 0.10% by mass.

[0166] The content of the modified monomer unit can be calculated by appropriately combining NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer. In addition, if the raw material composition is known, it can also be calculated from the raw material composition.

[0167] The form of the fluororesin composition (1) is not particularly limited, but it is preferably in the form of a powder.

[0168] The first fluororesin composition of the present disclosure preferably has an average secondary particle diameter of 5 to 700 μm, more preferably 10 μm or more, and even more preferably 20 μm or more, and more preferably 600 μm or less, even more preferably 500 μm or less, and particularly preferably 400 μm or less. The above average secondary particle diameter is measured using a Beckman Coulter laser diffraction particle size distribution analyzer (LS13 320) in a dry state at a vacuum pressure of 20 mH2O, and is equal to the particle diameter corresponding to 50% of the integrated particle size distribution (volume basis).

[0169] The fluororesin composition (1) preferably has a D90 of 10 μm or more, more preferably 30 μm or more, and even more preferably 50 μm or more, and preferably has a D90 of 600 μm or less, more preferably 500 μm or less, and even more preferably 400 μm or less. The above D90 is measured using a Beckman Coulter laser diffraction particle size analyzer (LS13 320) in a dry state at a vacuum pressure of 20 mH2O, and is equal to the particle diameter corresponding to 90% of the integrated particle size distribution (volume basis).

[0170] In order to further improve the tensile properties of the fluororesin composition (1), the content (total amount) of low-molecular-weight fluorine-containing compounds is preferably 1 ppm by mass or less, more preferably 500 ppb by mass or less, even more preferably 100 ppb by mass or less, even more preferably 50 ppb by mass or less, especially preferably 25 ppb by mass or less, particularly preferably 10 ppb by mass or less, especially more preferably 5 ppb by mass or less, especially especially preferably 1 ppb by mass or less, and most preferably less than 1 ppb by mass, relative to the fluororesin composition. The content of the low-molecular-weight fluorine-containing compound is measured by subjecting a sample to Soxhlet extraction with methanol and then using a liquid chromatograph mass meter (LC / MS / MS).

[0171] Examples of the low molecular weight fluorine-containing compound include fluorine-containing carboxylic acids having 4 or more carbon atoms and salts thereof, and fluorine-containing sulfonic acids having 4 or more carbon atoms and salts thereof, all of which may have an ether bond (—O—).

[0172] Examples of the low-molecular-weight fluorine-containing compound include anionic fluorine-containing surfactants, etc. The anionic fluorine-containing surfactant may be, for example, a surfactant containing fluorine atoms and having a total carbon number of 20 or less excluding the anionic group.

[0173] The anionic fluorine-containing surfactant may also be a surfactant containing fluorine in the anionic moiety having a molecular weight of 1,000 or less, or may be a surfactant containing fluorine in the anionic moiety having a molecular weight of 800 or less. The "anionic portion" refers to the portion of the fluorine-containing surfactant excluding the cation. For example, F(CF2) represented by the formula (I) below n1 In the case of COOM, "F(CF2) n1 The "COO" part.

[0174] The low-molecular-weight fluorine-containing compound also includes a fluorine-containing surfactant having a LogPOW of 3.5 or less. The LogPOW is a partition coefficient between 1-octanol and water, and is expressed as LogP (where P represents the ratio of the fluorine-containing surfactant concentration in octanol to the fluorine-containing surfactant concentration in water when a 1:1 octanol / water mixture containing the fluorine-containing surfactant undergoes phase separation). The LogPOW is calculated from the HPLC elution time of the sample solution using standard substances (heptanoic acid, octanoic acid, nonanoic acid, and decanoic acid) with known octanol / water partition coefficients under the following conditions: column: TOSOH ODS-120T column (φ4.6 mm×250 mm, manufactured by Tosoh Corporation), eluent: acetonitrile / 0.6% by mass HClO₄ / water=1 / 1 (vol / vol%), flow rate: 1.0 mL / min, sample amount: 300 μL, column temperature: 40°C, detection light: UV 210 nm. A calibration curve between each elution time and the known octanol / water partition coefficient is then prepared, and the LogPOW is calculated from the HPLC elution time of the sample solution based on this calibration curve.

[0175] Specific examples of the fluorine-containing surfactants include those described in U.S. Patent Application Publication Nos. 2007 / 0015864, 2007 / 0015865, 2007 / 0015866, 2007 / 0276103, 2007 / 0117914, 2007 / 142541, 2008 / 0015319, U.S. Patent No. 3,250,808, Examples of such compounds include those described in U.S. Pat. No. 3,271,341, JP 2003-119204 A, WO 2005 / 042593 A, WO 2008 / 060461 A, WO 2007 / 046377 A, JP 2007-119526 A, WO 2007 / 046482 A, WO 2007 / 046345 A, U.S. Patent Application Publication No. 2014 / 0228531 A, WO 2013 / 189824 A, and WO 2013 / 189826 A.

[0176] The anionic fluorine-containing surfactant may be a compound represented by the following general formula (N 0 ): X n0 -Rf n0 -Y 0 (N 0 ) (In the formula, X n0 is H, Cl or F. n0 is a linear, branched or cyclic alkylene group having 3 to 20 carbon atoms, in which some or all of the H's are substituted with F, and the alkylene group may contain one or more ether bonds, and some of the H's may be substituted with Cl. Y 0 is an anionic group.

[0177] Y 0 The anionic group may be -COOM, -SO2M, or -SO3M, and may be -COOM or -SO3M. M is H, metal atom, NR 74. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group. The metal atom includes alkali metals (Group 1) and alkaline earth metals (Group 2), such as Na, K, or Li. R 7 is H or C 1-10 may be an organic group of H or C 1-4 may be an organic group of H or C 1-4 The alkyl group may be: M is H, a metal atom, or NR 7 4, and may be H, an alkali metal (Group 1), an alkaline earth metal (Group 2), or NR 7 4, which may be H, Na, K, Li, or NH4.

[0178] Above Rf n0 may be one in which 50% or more of H is substituted with fluorine.

[0179] The general formula (N 0 The compound represented by the following general formula (N 1 ): X n0 -(CF2) m1 -Y 0 (N 1 ) (In the formula, X n0 is H, Cl, or F, m1 is an integer of 3 to 15, and Y 0 is as defined above, a compound represented by the following general formula (N 2 ): Rf n1 -O-(CF(CF3)CF2O) m2 CFX n1 -Y 0 (N 2 ) (In the formula, Rf n1 is a perfluoroalkyl group having 1 to 5 carbon atoms, m2 is an integer of 0 to 3, and X n1 is F or CF3, and Y 0is as defined above, a compound represented by the following general formula (N 3 ): Rf n2 (CH2) m3 -(Rf n3 ) q -Y 0 (N 3 ) (In the formula, Rf n2 is a partially or fully fluorinated alkyl group having 1 to 13 carbon atoms which may contain an ether bond and / or a chlorine atom, m3 is an integer of 1 to 3, and Rf n3 is a linear or branched perfluoroalkylene group having 1 to 3 carbon atoms, q is 0 or 1, and Y 0 is as defined above, a compound represented by the following general formula (N 4 ): Rf n4 -O-(CY n1 Y n2 ) p CF2-Y 0 (N 4 ) (In the formula, Rf n4 is a linear or branched partially or fully fluorinated alkyl group having 1 to 12 carbon atoms, which may contain an ether bond; Y n1 and Y n2 are the same or different and are H or F, p is 0 or 1, and Y 0 is as defined above.) and a compound represented by the general formula (N 5 ): [ka] (In the formula, X n2 , X n3 and X n4 Rf may be the same or different and are H, F, or a linear or branched partially or fully fluorinated alkyl group having 1 to 6 carbon atoms, which may contain an ether bond. n5 is a linear or branched partially or fully fluorinated alkylene group having 1 to 3 carbon atoms, which may contain an ether bond; L is a linking group; Y 0 is as defined above, where X n2, X n3 , X n4 and Rf n5 The total number of carbon atoms is 18 or less.

[0180] The general formula (N 0 ) More specifically, the compounds represented by the formula (I) include perfluorocarboxylic acids (I) represented by the following general formula (I), ω-H perfluorocarboxylic acids (II) represented by the following general formula (II), perfluoroethercarboxylic acids (III) represented by the following general formula (III), perfluoroalkyl alkylenecarboxylic acids (IV) represented by the following general formula (IV), alkoxy fluorocarboxylic acids (V) represented by the following general formula (V), perfluoroalkyl sulfonic acids (VI) represented by the following general formula (VII), ω-H perfluorosulfonic acids (VII) represented by the following general formula (VII), perfluoroalkyl alkylene sulfonic acids (VIII) represented by the following general formula (VIII), alkyl alkylene carboxylic acids (IX) represented by the following general formula (IX), fluorocarboxylic acids (X) represented by the following general formula (X), alkoxy fluorosulfonic acids (XI) represented by the following general formula (XI), compounds (XII) represented by the following general formula (XII), and compounds (XIII) represented by the following general formula (XIII).

[0181] The perfluorocarboxylic acid (I) is represented by the following general formula (I): F(CF2) n1 COOM (I) (wherein n1 is an integer of 3 to 14, and M is H, a metal atom, or NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group.

[0182] The ω-H perfluorocarboxylic acid (II) is represented by the following general formula (II): H(CF2) n2 COOM (II) (wherein n2 is an integer of 4 to 15, and M is as defined above).

[0183] The perfluoroethercarboxylic acid (III) is represented by the following general formula (III): Rf 1 -O-(CF(CF3)CF2O) n3 CF(CF3)COOM (III) (In the formula, Rf 1 is a perfluoroalkyl group having 1 to 5 carbon atoms, n3 is an integer of 0 to 3, and M is as defined above.

[0184] The perfluoroalkyl alkylene carboxylic acid (IV) is represented by the following general formula (IV): Rf 2 (CH2) n4 Rf 3 COOM (IV) (In the formula, Rf 2 is a perfluoroalkyl group having 1 to 5 carbon atoms, and Rf 3 is a linear or branched perfluoroalkylene group having 1 to 3 carbon atoms, n4 is an integer of 1 to 3, and M is as defined above.

[0185] The alkoxyfluorocarboxylic acid (V) is represented by the following general formula (V): Rf 4 -O-CY 1 Y 2 CF2-COOM (V) (In the formula, Rf 4 is a linear or branched partially or fully fluorinated alkyl group having 1 to 12 carbon atoms, which may contain an ether bond and / or a chlorine atom, and Y 1 and Y 2 are the same or different and are H or F, and M is as defined above.

[0186] The perfluoroalkylsulfonic acid (VI) is represented by the following general formula (VI): F(CF2) n5SO3M (VI) (wherein n5 is an integer of 3 to 14, and M is as defined above).

[0187] The ω-H perfluorosulfonic acid (VII) is represented by the following general formula (VII): H(CF2) n6 SO3M (VII) (wherein n6 is an integer of 4 to 14, and M is as defined above).

[0188] The perfluoroalkyl alkylene sulfonic acid (VIII) is represented by the following general formula (VIII): Rf 5 (CH2) n7 SO3M (VIII) (In the formula, Rf 5 is a perfluoroalkyl group having 1 to 13 carbon atoms, n7 is an integer of 1 to 3, and M is as defined above.

[0189] The alkyl alkylene carboxylic acid (IX) is represented by the following general formula (IX): Rf 6 (CH2) n8 COOM (IX) (In the formula, Rf 6 is a linear or branched partially or fully fluorinated alkyl group having 1 to 13 carbon atoms which may contain an ether bond, n8 is an integer of 1 to 3, and M is as defined above.

[0190] The fluorocarboxylic acid (X) is represented by the following general formula (X): Rf 7 -O-Rf 8 -O-CF2-COOM (X) (In the formula, Rf 7 is a linear or branched, partially or fully fluorinated alkyl group having 1 to 6 carbon atoms, which may contain an ether bond and / or a chlorine atom, and Rf 8is a linear or branched, partially or fully fluorinated alkyl group having 1 to 6 carbon atoms, and M is as defined above.

[0191] The alkoxyfluorosulfonic acid (XI) is represented by the following general formula (XI): Rf 9 -O-CY 1 Y 2 CF2-SO3M (XI) (In the formula, Rf 9 is a linear or branched alkyl group having 1 to 12 carbon atoms, which may contain an ether bond, and which may contain chlorine, and which is partially or completely fluorinated; Y 1 and Y 2 are the same or different and are H or F, and M is as defined above.

[0192] The compound (XII) is represented by the following general formula (XII): [ka] (In the formula, X 1 , X 2 and X 3 may be the same or different and are H, F, and linear or branched partially or fully fluorinated alkyl groups having 1 to 6 carbon atoms, which may contain ether bonds; Rf 10 is a perfluoroalkylene group having 1 to 3 carbon atoms, L is a linking group, and Y 0 is an anionic group. Y 0 may be -COOM, -SO2M, or -SO3M, and may be -SO3M or COOM (wherein M is as defined above). Examples of L include a single bond and a partially or fully fluorinated alkylene group having 1 to 10 carbon atoms which may contain an ether bond.

[0193] The compound (XIII) is represented by the following general formula (XIII): Rf 11 -O-(CF2CF(CF3)O)n9 (CF2O) n10 CF2COOM (XIII) (In the formula, Rf 11 is a fluoroalkyl group containing chlorine and having 1 to 5 carbon atoms, n9 is an integer of 0 to 3, n10 is an integer of 0 to 3, and M is as defined above. Compound (XIII) is represented by the formula: CF2ClO(CF2CF(CF3)O) n9 (CF2O) n10 CF2COONH4 (a mixture having an average molecular weight of 750, wherein n9 and n10 are defined above).

[0194] As mentioned above, examples of the anionic fluorine-containing surfactant include carboxylic acid surfactants and sulfonic acid surfactants.

[0195] The above fluorine-containing surfactant may be one type of fluorine-containing surfactant or a mixture containing two or more types of fluorine-containing surfactants.

[0196] Examples of the fluorine-containing surfactant include compounds represented by the following formula: The fluorine-containing surfactant may be a mixture of these compounds. F(CF2)7COOM, F(CF2)5COOM, H(CF2)6COOM, H(CF2)7COOM, CF3O(CF2)3OCHFCF2COOM, C3F7OCF(CF3)CF2OCF(CF3)COOM, CF3CF2CF2OCF(CF3)COOM, CF3CF2OCF2CF2OCF2COOM, C2F5OCF(CF3)CF2OCF(CF3)COOM, CF3OCF(CF3)CF2OCF(CF3)COOM, CF2ClCF2CF2OCF(CF3)CF2OCF2COOM, CF2ClCF2CF2OCF2CF(CF3)OCF2COOM, CF2ClCF(CF3)OCF(CF3)CF2OCF2COOM, CF2ClCF(CF3)OCF2CF(CF3)OCF2COOM, [ka] (In each formula, M is H, metal atom, NR 7 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. 7 is defined above.)

[0197] The fluororesin composition (1) can be produced, for example, by mixing powder of the fluororesin A, particles of the fluororesin B1, a filler, and, if necessary, particles of the fluororesin C.

[0198] The particles of fluororesin B1 may be mixed with the powder of fluororesin A in the form of a powder, or may be mixed with the powder of fluororesin A in the form of an aqueous dispersion. However, mixing with the powder of fluororesin A in the form of an aqueous dispersion is preferred, as this allows the production of a fluororesin composition with even more excellent tensile properties.

[0199] The aqueous dispersion containing particles of the fluororesin B1 can be produced by a known method. For example, it can be produced by emulsion polymerization of the monomers necessary to constitute the fluororesin B1 in an aqueous medium in the presence of an anionic surfactant and a polymerization initiator. In the emulsion polymerization, chain transfer agents, buffers, pH adjusters, stabilizing aids, dispersion stabilizers, etc. may be used as needed. Those skilled in the art can control the composition and physical properties of the fluororesin B1, the physical properties of the particles, and the like, by adjusting the conditions of the emulsion polymerization.

[0200] The aqueous dispersion may contain a hydrocarbon surfactant. The hydrocarbon surfactant preferably does not contain a fluorine atom. The hydrocarbon surfactant may be one that was used in the emulsion polymerization, or may be one that was added after the emulsion polymerization.

[0201] As the hydrocarbon surfactant, for example, those described in JP-A Nos. 2013-542308, 2013-542309, and 2013-542310 can be used.

[0202] Hydrocarbon surfactants have a hydrophilic portion and a hydrophobic portion on the same molecule. They can be cationic, nonionic, or anionic.

[0203] Cationic surfactants typically have a positively charged hydrophilic portion, such as an alkylated ammonium halide, such as an alkylated ammonium bromide, and a hydrophobic portion, such as a long-chain fatty acid.

[0204] Anionic surfactants typically have a hydrophilic portion, such as a carboxylate, sulfonate, or sulfate, and a hydrophobic portion, which is a long chain hydrocarbon moiety, such as an alkyl.

[0205] Nonionic surfactants typically contain no charged groups and have a hydrophobic portion that is a long hydrocarbon chain. The hydrophilic portion of the nonionic surfactant contains water-soluble functional groups, such as ethylene ether chains derived from polymerization with ethylene oxide.

[0206] The hydrocarbon surfactant is preferably an anionic surfactant or a nonionic surfactant.

[0207] Examples of anionic hydrocarbon surfactants include Versatic (registered trademark) 10 manufactured by Resolution Performance Products and Avanel S series (S-70, S-74, etc.) manufactured by BASF.

[0208] Anionic hydrocarbon surfactants include RLM 1 (In the formula, R is a linear or branched alkyl group having 1 or more carbon atoms which may have a substituent, or a cyclic alkyl group having 3 or more carbon atoms which may have a substituent, and when the alkyl group has 3 or more carbon atoms, it may contain a monovalent or divalent heterocycle or may be a cyclic ring. L is -ArSO3 - , -SO3 - , -SO4-, -PO3 - or -COO - and M 1 is H, metal atom, NR 5 4(R 5 may be the same or different and are H or an organic group having 1 to 10 carbon atoms), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. -ArSO3 - is an aryl sulfonate. ) Specifically, CH3-(CH2) n -LM 1 (wherein n is an integer of 6 to 17; L and M 1 (but the same as above). Mixtures where R is an alkyl group having 12 to 16 carbon atoms and L is sulfate or sodium dodecyl sulfate (SDS) can also be used.

[0209] Anionic hydrocarbon surfactants include R 6 (-LM 1 )2(wherein, R 6 is a linear or branched alkylene group having one or more carbon atoms which may have a substituent, or a cyclic alkylene group having three or more carbon atoms which may have a substituent, and when the alkylene group has three or more carbon atoms, it may contain a monovalent or divalent heterocycle or may be a cyclic ring. - , -SO3 - , -SO4-, -PO3 - or -COO - and M 1 is H, metal atom, NR 5 4(R5 may be the same or different and are H or an organic group having 1 to 10 carbon atoms), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. -ArSO3 - is an aryl sulfonate. )

[0210] Anionic hydrocarbon surfactants include R 7 (-LM 1 )3(wherein, R 7 is a linear or branched alkylidyne group having one or more carbon atoms which may have a substituent, or a cyclic alkylidyne group having three or more carbon atoms which may have a substituent, and when the alkylidyne group has three or more carbon atoms, it may contain a monovalent or divalent heterocycle or may be a cyclic ring. - , -SO3 - , -SO4-, -PO3 - or -COO - and M 1 is H, metal atom, NR 5 4(R 5 may be the same or different and are H or an organic group having 1 to 10 carbon atoms), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. -ArSO3 - is an aryl sulfonate. )

[0211] Anionic hydrocarbon surfactants also include the sulfosuccinate surfactant Lankropol® K8300 from Akzo Nobel Surface Chemistry LLC. Examples of sulfosuccinate hydrocarbon surfactants include sodium diisodecyl sulfosuccinate (Emulsogen® SB10 from Clariant) and sodium diisotridecyl sulfosuccinate (Polirol® TR / LNA from Cesapinia Chemicals).

[0212] Anionic hydrocarbon surfactants include PolyFox (registered trademark) surfactants from Omnova Solutions, Inc. TM PF-156A, PolyFox TM PF-136A, etc.)

[0213] Examples of the nonionic surfactant include ether-type nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, and polyoxyethylene alkylene alkyl ethers; polyoxyethylene derivatives such as ethylene oxide / propylene oxide block copolymers; ester-type nonionic surfactants such as polyoxyethylene fatty acid esters (polyoxyethylene alkyl esters), sorbitan fatty acid esters (sorbitan alkyl esters), polyoxyethylene sorbitan fatty acid esters (polyoxyethylene sorbitan alkyl esters), polyoxyethylene sorbitol fatty acid esters, and glycerin fatty acid esters (glycerol esters); amine-based nonionic surfactants such as polyoxyethylene alkylamines and alkylalkanolamides; and derivatives thereof. These may be used alone or in combination of two or more. The non-ionic surfactant may be a non-fluorinated non-ionic surfactant.

[0214] Examples of the polyoxyethylene alkyl ether include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, and polyoxyethylene behenyl ether.

[0215] Examples of the polyoxyethylene alkylphenyl ether include polyoxyethylene nonylphenyl ether and polyoxyethylene octylphenyl ether.

[0216] Specific examples of the polyoxyethylene fatty acid ester include polyethylene glycol monolaurate, polyethylene glycol monooleate, and polyethylene glycol monostearate.

[0217] Examples of the sorbitan fatty acid ester include sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, and sorbitan monooleate.

[0218] Examples of the polyoxyethylene sorbitan fatty acid ester include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, and polyoxyethylene sorbitan monostearate.

[0219] Examples of the glycerin fatty acid ester include glycerol monomyristate, glycerol monostearate, and glycerol monooleate.

[0220] The derivatives include polyoxyethylene alkylamines, polyoxyethylene alkylphenyl-formaldehyde condensates, polyoxyethylene alkyl ether phosphates, and the like.

[0221] The ether-type nonionic surfactant and the ester-type nonionic surfactant may have an HLB value of 10-18.

[0222] Examples of nonionic hydrocarbon surfactants include the Triton (registered trademark) X series (X15, X45, X100, etc.), Tergitol (registered trademark) 15-S series, Tergitol (registered trademark) TMN series (TMN-6, TMN-10, TMN-100, etc.), and Tergitol (registered trademark) L series, all manufactured by Dow Chemical Company; the Pluronic (registered trademark) R series (31R1, 17R2, 10R5, 25R4 (m to 22, n to 23)), T-Det series (A138), and Iconol (registered trademark) TDA series (TDA-6, TDA-9, TDA-10), all manufactured by BASF.

[0223] In the compound constituting the nonionic surfactant, the hydrophobic group may be any of an alkylphenol group, a linear alkyl group, and a branched alkyl group, but it is preferable that the hydrophobic group does not have a benzene ring, such as a compound that does not have an alkylphenol group in its structure.

[0224] Among the nonionic surfactants, those having an ether bond (-O-) are preferred, the above-mentioned ether-type nonionic surfactants are more preferred, and polyoxyethylene alkyl ethers are even more preferred. The polyoxyethylene alkyl ethers are preferably those having a polyoxyethylene alkyl ether structure with an alkyl group having 10 to 20 carbon atoms, and more preferably those having a polyoxyethylene alkyl ether structure with an alkyl group having 10 to 15 carbon atoms. The alkyl group in the polyoxyethylene alkyl ether structure preferably has a branched structure.

[0225] The content of the hydrocarbon surfactant is preferably 12% by mass or less, more preferably 8% by mass or less, even more preferably 6% by mass or less, even more preferably 4% by mass or less, particularly preferably 2% by mass or less, and particularly preferably 1% by mass or less, based on the solid content of the aqueous dispersion, from the viewpoint of producing a fluororesin composition with less coloration and more excellent tensile properties. The content of the hydrocarbon surfactant may also be 1 ppm by mass or more, 10 ppm by mass or more, 100 ppm by mass or more, or 500 ppm by mass or more.

[0226] The aqueous dispersion obtained by the emulsion polymerization or the aqueous dispersion containing the hydrocarbon surfactant may be contacted with an anion exchange resin or a mixed bed containing an anion exchange resin and a cation exchange resin, concentrated, or treated with both. By carrying out the above treatment, low-molecular-weight fluorine-containing compounds can be removed. As the above treatment, known treatments can be used.

[0227] The mixture obtained by mixing powder of fluororesin A with an aqueous dispersion containing particles of fluororesin B1 may be coagulated. Examples of coagulation methods include freezing or mechanical shearing to aggregate the emulsified particles. Stirring may be performed while adding a coagulant, such as a water-soluble organic compound (e.g., methanol or acetone), an inorganic salt (e.g., potassium nitrate or ammonium carbonate), or an inorganic acid (e.g., hydrochloric acid, sulfuric acid, or nitric acid). The coagulation may also be performed continuously using an in-line mixer or the like.

[0228] The mixture is dried to obtain a fluororesin composition. The wet powder obtained by the coagulation may be dried. The drying method is not particularly limited, and any known method can be used, for example, vacuum, high frequency, hot air, or the like. The drying temperature is preferably 50°C or higher, more preferably 70°C or higher, even more preferably 100°C or higher, particularly preferably 150°C or higher, and is preferably 300°C or lower, more preferably 250°C or lower.

[0229] The particles of fluororesin C may be mixed in the form of a powder with the powder of fluororesin A (and particles of fluororesin B1), or may be mixed in the form of an aqueous dispersion with the powder of fluororesin A (and particles of fluororesin B1).

[0230] The resulting fluororesin composition may be pulverized by a known method, for example, using a pulverizer such as an air jet mill, a hammer mill, a force mill, a stone mill, or a freeze pulverizer.

[0231] The resulting fluororesin composition may be granulated, thereby obtaining a fluororesin composition with a high apparent density and excellent handleability. The granulation method may be any known method, such as underwater granulation, hot water granulation, emulsion dispersion granulation, emulsion hot water granulation, solventless granulation, or dry solvent granulation.

[0232] The first fluororesin composition of the present disclosure is also preferably a fluororesin composition (also referred to as fluororesin composition (2a)) that contains a fluororesin A that does not exhibit melt fluidity and has a history of being heated to a temperature equal to or higher than its melting point, a fluororesin B2 that does not exhibit melt fluidity and has been polymerized by suspension polymerization and has no history of being heated to a temperature equal to or higher than its melting point, and a filler, and has an apparent density of 0.42 g / ml or more.

[0233] The fluororesin composition (2a) contains a fluororesin B2 polymerized by suspension polymerization that has no history of being heated to a temperature equal to or higher than its melting point, and has an apparent density within a specific range. Therefore, despite containing a fluororesin A that has a history of being heated to a temperature equal to or higher than its melting point, the composition has excellent handleability (e.g., handleability during transportation and compression molding). Furthermore, the fluororesin composition (2a) has good tensile properties (for example, tensile strength at break, tensile strain at break).

[0234] The fluororesin composition (2a) preferably has one or more melting points in the temperature range below 333°C and one or more melting points in the temperature range of 333 to 360°C. The temperature range of less than 333°C is more preferably less than 332°C, even more preferably less than 331°C, and is preferably 100°C or higher, more preferably 140°C or higher, and even more preferably 160°C or higher. The temperature range of 333 to 360°C is more preferably 334°C or higher, even more preferably 335°C, and is more preferably 355°C or lower, even more preferably 350°C or lower. Having melting points in the above two temperature ranges means that the fluororesin composition contains fluororesin A, which has a history of being heated to a temperature equal to or higher than its melting point and does not exhibit melt flowability, and fluororesin B2, which has no history of being heated to a temperature equal to or higher than its melting point and does not exhibit melt flowability.

[0235] As the fluororesin A and the filler in the fluororesin composition (2a), those mentioned above can be used.

[0236] The fluororesin B2 has no history of being heated to a temperature equal to or higher than its melting point.

[0237] The fluororesin B2 preferably has a melting point of 100 to 360° C. The melting point is more preferably 140° C. or higher, and even more preferably 160° C. or higher, and is more preferably 355° C. or lower, and even more preferably 350° C. or lower.

[0238] The fluororesin B2 preferably has one or more melting points in the temperature range of 333 to 360° C. The temperature range is more preferably 334° C. or higher, and even more preferably 335° C. or higher, and is more preferably 355° C. or lower, and even more preferably 350° C. or lower. The fact that the melting point is within the above range indicates that there is no history of heating to a temperature equal to or higher than the melting point. In addition to the above melting point, the material may also have a melting point in a temperature range below 333°C.

[0239] The fluororesin B2 does not exhibit melt fluidity, as described above.

[0240] The fluororesin B2 is preferably PTFE, which may be a high molecular weight PTFE.

[0241] The PTFE (high molecular weight PTFE) as the fluororesin B2 preferably exhibits at least one endothermic peak in the range of 333 to 347°C in a heat of fusion curve when heated at a rate of 10°C / min using a differential scanning calorimeter (DSC), and the heat of fusion between 290 and 350°C calculated from the heat of fusion curve is 62 mJ / mg or more.

[0242] The PTFE as the fluororesin B2 preferably has a standard specific gravity (SSG) of 2.130 to 2.280. The standard specific gravity is measured by the water displacement method in accordance with ASTM D 792 using a sample molded in accordance with ASTM D4895 89. The term "high molecular weight" for PTFE that has not been heated to a temperature equal to or higher than its melting point means that the standard specific gravity is within the above range.

[0243] The PTFE used as the fluororesin B2 generally has non-melt secondary processability, as described above.

[0244] The PTFE as the fluororesin B2 may be a homopolymer of TFE, or a modified PTFE containing 99.0% by mass or more of polymerized units based on TFE and 1.0% by mass or less of polymerized units based on a modifying monomer (modifying monomer units). The modified PTFE may consist only of polymerized units based on TFE and modifying monomer units. Modified PTFE is preferred in that it can provide a fluororesin composition having a higher apparent density and better handleability, and in that it can provide a fluororesin composition having better tensile properties.

[0245] The modified PTFE preferably has a content of the modified monomer unit in the range of 0.00001 to 1.0% by mass relative to the total polymerized units. The lower limit of the content of the modified monomer unit is more preferably 0.0001% by mass, even more preferably 0.001% by mass, even more preferably 0.005% by mass, and especially preferably 0.010% by mass. The upper limit of the content of the modified monomer unit is preferably 0.90% by mass, more preferably 0.50% by mass, even more preferably 0.40% by mass, even more preferably 0.30% by mass, especially preferably 0.20% by mass, and especially preferably 0.10% by mass.

[0246] The modifying monomers that can be used in the above PTFE as the fluororesin B2 are the same as those exemplified for the PTFE (high molecular weight PTFE) as the fluororesin A.

[0247] Fluororesin B2 is polymerized by suspension polymerization. Fluororesin polymerized by suspension polymerization and not exhibiting melt fluidity is less likely to become fibrous, so the apparent density of the fluororesin composition can be increased, and handling properties can be improved.

[0248] The fluororesin B2 which is polymerized by suspension polymerization and does not exhibit melt fluidity preferably satisfies all of the following requirements. (i) The proportion of particles with a particle size of 1 μm or less as determined by image processing using a scanning electron microscope (SEM) is 30% or less. (ii) The amount of anionic fluorine-containing surfactant measured by liquid chromatography / mass spectrometry (LC / MS / MS) using an extract obtained by Soxhlet extraction with methanol is 1 ppm by mass or less.

[0249] The suspension polymerization can be carried out by a known method. For example, a polymerization initiator is dispersed in an aqueous medium without using an anionic fluorinated surfactant or with a limited amount of an anionic fluorinated surfactant, and the monomers necessary for constituting the fluororesin B2 are polymerized to directly isolate a granular powder of the fluororesin B2.

[0250] As the fluororesin B2, a powder obtained directly by the above suspension polymerization may be used, or a powder obtained by pulverizing and / or granulating the above powder may be used. The above-mentioned pulverization may be carried out by a known method, and can be carried out by a pulverization method using a pulverizer such as a hammer mill, a pin mill, a jet mill, or a cutter mill. The granulation may be carried out by a known method such as underwater granulation, hot water granulation, emulsion dispersion granulation, emulsion hot water granulation, solventless granulation, or dry solvent granulation.

[0251] The fluororesin composition (2a) may contain particles of the fluororesin B2. The particles of the fluororesin B2 may be secondary particles of the fluororesin B2.

[0252] The particles of the fluororesin B2 preferably have an average secondary particle diameter of 1 to 700 μm. The average secondary particle diameter is more preferably 5 μm or more, even more preferably 10 μm or more, and even more preferably 20 μm or more. It is also more preferably 500 μm or less, even more preferably 150 μm or less, and even more preferably 100 μm or less. The above average secondary particle diameter is measured using a Beckman Coulter laser diffraction particle size distribution analyzer (LS13 320) in a dry state at a vacuum pressure of 20 mH2O, and is equal to the particle diameter corresponding to 50% of the integrated particle size distribution (volume basis).

[0253] The particles of the fluororesin B2 preferably have a D90 of 10 μm or more, more preferably 30 μm or more, and even more preferably 50 μm or more, and preferably 600 μm or less, more preferably 500 μm or less, and even more preferably 400 μm or less. The above D90 is measured using a Beckman Coulter laser diffraction particle size analyzer (LS13 320) in a dry state at a vacuum pressure of 20 mH2O, and is equal to the particle diameter corresponding to 90% of the integrated particle size distribution (volume basis).

[0254] The fluororesin composition (2a) has an apparent density of 0.42 g / ml or more. When the apparent density is within the above range, the fluororesin composition (2a) has excellent handleability. In terms of easier handling, the apparent density is preferably 0.45 g / ml or more, and more preferably 0.47 g / ml or more. There is no particular upper limit, but it may be 1.00 g / ml. The apparent density is measured in accordance with JIS K 6891.

[0255] The content of fluororesin A in the fluororesin composition (2a) is preferably 10 to 90% by mass relative to the fluororesin composition, in order to further improve the tensile properties. The content is more preferably 20% by mass or more, even more preferably 30% by mass or more, even more preferably 40% by mass or more, and particularly preferably 50% by mass or more, and is more preferably 85% by mass or less, even more preferably 80% by mass or less, even more preferably less than 80% by mass, especially preferably 75% by mass or less, and particularly preferably 70% by mass or less.

[0256] The content of fluororesin B2 in the fluororesin composition (2a) is preferably 10 to 90% by mass relative to the fluororesin composition, in order to further improve the tensile properties. The content is more preferably 15% by mass or more, even more preferably 20% by mass or more, even more preferably more than 20% by mass, particularly preferably 25% by mass or more, and particularly preferably 30% by mass or more, and is more preferably 80% by mass or less, even more preferably 70% by mass or less, even more preferably 60% by mass or less, and particularly preferably 50% by mass or less.

[0257] The total amount of fluororesins A and B2 in the fluororesin composition (2a) is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 98% by mass or more, based on the fluororesin composition.

[0258] The fluororesin composition (2a) contains TFE units and modified monomer units derived from a modified monomer copolymerizable with TFE, and the amount of the modified monomer units is preferably 1.0 mass% or less relative to the total polymerized units, and the amount of TFE units is preferably 99.0 mass% or more.

[0259] The lower limit of the content of the modified monomer unit in the fluororesin composition (2a) may be 0% by mass, more preferably 0.0001% by mass, even more preferably 0.001% by mass, even more preferably 0.005% by mass, and particularly preferably 0.010% by mass. The upper limit of the content of the modified monomer unit is preferably 0.90% by mass, more preferably 0.50% by mass, even more preferably 0.40% by mass, even more preferably 0.30% by mass, especially preferably 0.20% by mass, and particularly preferably 0.10% by mass. The content of the modified monomer unit can be calculated by appropriately combining NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer. In addition, if the raw material composition is known, it can also be calculated from the raw material composition.

[0260] In one preferred embodiment of the fluororesin composition (2a), the fluororesin B2 is a homopolymer of TFE, and the content of the fluororesin A is 50% by mass or more and less than 80% by mass of the fluororesin composition. In this embodiment, the content of the fluororesin A is more preferably 75% by mass or less, and even more preferably 70% by mass or less, of the fluororesin composition.

[0261] Another preferred embodiment of the fluororesin composition (2a) is one in which the content of fluororesin A is 50% by mass or more relative to the fluororesin composition, and the tensile strength of the fluororesin composition is 20 MPa or more. The tensile breaking strength is measured in accordance with ASTM D1708 using a dumbbell punched from a molded article sintered in the following steps: placing 35 g of the fluororesin composition in a φ100 mm mold, compression-molding the composition under a pressure of 30 MPa for 1 minute, raising the temperature from room temperature to 300°C over 3 hours, then raising the temperature from 300°C to 370°C over 4 hours, holding the temperature at 370°C for 12 hours, cooling to 300°C over 5 hours, and then cooling to room temperature over 1 hour. In this embodiment, it is also preferable that the fluororesin B2 is a homopolymer of TFE.

[0262] The first fluororesin composition of the present disclosure is also preferably a fluororesin composition (also referred to as fluororesin composition (2b)) comprising: a fluororesin A that has a history of being heated to a temperature equal to or higher than its melting point and does not exhibit melt fluidity; a fluororesin B2 that has no history of being heated to a temperature equal to or higher than its melting point and does not exhibit melt fluidity and has been polymerized by suspension polymerization; and a filler, and which comprises TFE units and modified monomer units based on a modified monomer copolymerizable with TFE. The fluororesin composition (2b) has a specific monomer composition and therefore has excellent handleability (e.g., handleability during transportation and compression molding) despite containing the fluororesin A that has a history of being heated to a temperature equal to or higher than the melting point. In addition, the fluororesin composition (2b) has good tensile properties (for example, tensile strength at break, tensile strain at break).

[0263] The fluororesin composition (2b) preferably has one or more melting points in the temperature range below 333°C and one or more melting points in the temperature range of 333 to 360°C. The temperature range of less than 333°C is more preferably less than 332°C, even more preferably less than 331°C, and is preferably 100°C or higher, more preferably 140°C or higher, and even more preferably 160°C or higher. The temperature range of 333 to 360°C is more preferably 334°C or higher, even more preferably 335°C, and is more preferably 355°C or lower, even more preferably 350°C or lower. Having melting points in the above two temperature ranges means that the fluororesin composition contains fluororesin A, which has a history of being heated to a temperature equal to or higher than its melting point and does not exhibit melt flowability, and fluororesin B2, which has no history of being heated to a temperature equal to or higher than its melting point and does not exhibit melt flowability.

[0264] As the fluororesin A and the filler in the fluororesin composition (2b), those mentioned above can be used.

[0265] The fluororesin B2 in the fluororesin composition (2b) may be the same as the fluororesin B2 in the fluororesin composition (2a), and is preferably a modified PTFE containing 99.0 mass% or more of polymerized units based on TFE (TFE units) and 1.0 mass% or less of polymerized units based on a modified monomer (modified monomer units). The fluororesin B2 may consist only of TFE units and modified monomer units. The modifying monomer may be the same as the monomer described above for the modified PTFE as the fluororesin B2 in the fluororesin composition (2a). The preferred range of the content of the modifying monomer unit is the same as the range described for the fluororesin composition (2a).

[0266] The constitution of the fluororesin B2 in the fluororesin composition (2b) other than the composition is the same as that of the fluororesin B2 in the fluororesin composition (2a).

[0267] The fluororesin composition (2b) contains TFE units and modified monomer units based on a modified monomer copolymerizable with TFE. The fluororesin composition (2b) may contain only TFE units and modified monomer units as polymerized units.

[0268] In order to further improve the handleability and tensile properties of the fluororesin composition, the content of the modified monomer unit is preferably 1.0 mass% or less based on the total polymerized units constituting the fluororesin composition. The lower limit of the content of the modified monomer unit is preferably 0.00001 mass%, more preferably 0.0001 mass%, even more preferably 0.001 mass%, even more preferably 0.005 mass%, and particularly preferably 0.010 mass%. The upper limit of the content of the modified monomer unit is preferably 0.90 mass%, more preferably 0.50 mass%, even more preferably 0.40 mass%, even more preferably 0.30 mass%, even more preferably 0.20 mass%, and particularly preferably 0.10 mass%.

[0269] The fluororesin composition (2b) preferably contains TFE units in an amount of 99.0 mass % or more based on the total polymerized units.

[0270] The content of the polymerized units constituting the fluororesin composition (2b) can be calculated by appropriately combining NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer. In addition, when the raw material composition is known, it can also be determined by calculation from the raw material composition.

[0271] The contents of the fluororesins A and B2 and the total amount of the fluororesins A and B in the fluororesin composition (2b) are the same as those described for the fluororesin composition (2a).

[0272] The fluororesin composition (2b) preferably has an apparent density of 0.42 g / ml or more, more preferably 0.45 g / ml or more, and even more preferably 0.47 g / ml or more, in terms of easier handling. The upper limit is not particularly limited, but may be 1.00 g / ml. The apparent density is measured in accordance with JIS K 6891.

[0273] The form of the fluororesin compositions (2a) and (2b) is not particularly limited, but it is preferable that they are in the form of powder.

[0274] In the fluororesin compositions (2a) and (2b), the maximum linear length of the particles of fluororesin A is preferably smaller than the maximum linear length of the particles of fluororesin B2. When the maximum linear lengths of the particles of fluororesins A and B2 satisfy the above relationship, the apparent density of the fluororesin composition can be increased, further improving handleability. In addition, since there is no need to perform a deformation treatment to increase the maximum linear length of the particles of fluororesin A, the production cost of the fluororesin composition can be reduced.

[0275] The fluororesin compositions (2a) and (2b) preferably satisfy all of the following requirements: (i) The proportion of particles with a particle size of 1 μm or less as determined by image processing using a scanning electron microscope (SEM) is 30% or less. (ii) The amount of anionic fluorine-containing surfactant measured by liquid chromatography / mass spectrometry (LC / MS / MS) using an extract obtained by Soxhlet extraction with methanol is 1 ppm by mass or less.

[0276] The fluororesin compositions (2a) and (2b) preferably have an angle of repose of less than 40°, more preferably less than 38°, and even more preferably less than 35°, in order to have excellent fluidity and easier handling. The above angle of repose is a value obtained by placing a funnel with a total height of 115 mm, a foot diameter of φ26 mm, a foot length of 35 mm, and an intake opening of 60° so that the height from the bottom of the funnel to the sample drop surface is 100 mm, dropping 40 g of sample from the funnel, and measuring the angle of the lower half of the peak of the dropped sample with a protractor.

[0277] The fluororesin compositions (2a) and (2b) preferably have an average secondary particle size of 5 to 700 μm, more preferably 10 μm or more, even more preferably 20 μm or more, and more preferably 600 μm or less, even more preferably 500 μm or less, and particularly preferably 400 μm or less. The above average secondary particle diameter is measured using a Beckman Coulter laser diffraction particle size distribution analyzer (LS13 320) in a dry state at a vacuum pressure of 20 mH2O, and is equal to the particle diameter corresponding to 50% of the integrated particle size distribution (volume basis).

[0278] The fluororesin compositions (2a) and (2b) preferably have a D90 of 10 μm or more, more preferably 30 μm or more, and even more preferably 50 μm or more, and preferably 600 μm or less, more preferably 500 μm or less, and even more preferably 400 μm or less. The above D90 is measured using a Beckman Coulter laser diffraction particle size analyzer (LS13 320) in a dry state at a vacuum pressure of 20 mH2O, and is equal to the particle diameter corresponding to 90% of the integrated particle size distribution (volume basis).

[0279] In the fluororesin compositions (2a) and (2b), the content (total amount) of low-molecular-weight fluorine-containing compounds is preferably 1 ppm by mass or less, more preferably 500 ppb by mass or less, even more preferably 100 ppb by mass or less, even more preferably 50 ppb by mass or less, especially preferably 25 ppb by mass or less, particularly preferably 10 ppb by mass or less, especially more preferably 5 ppb by mass or less, especially especially preferably 1 ppb by mass or less, and most preferably less than 1 ppb by mass, in order to further improve the tensile properties of the fluororesin compositions. The content of the low-molecular-weight fluorine-containing compound is measured by subjecting a sample to Soxhlet extraction with methanol and then using a liquid chromatograph mass meter (LC / MS / MS).

[0280] Examples of the low molecular weight fluorine-containing compound include the compounds exemplified for the fluororesin composition (1).

[0281] The fluororesin compositions (2a) and (2b) can be produced, for example, by mixing powder of fluororesin A, particles of fluororesin B2, and a filler. The particles of fluororesin B2 are preferably mixed in the form of powder with powder of fluororesin A. The mixing method is not particularly limited, and known methods can be used. Mixing can also be carried out in a pulverizer. In order to easily obtain a fluororesin composition having a higher apparent density and better handleability, it is preferable that the maximum linear length of the particles of fluororesin A is smaller than the maximum linear length of the particles of fluororesin B2.

[0282] The resulting fluororesin composition may be pulverized by a known method, for example, using a pulverizer such as an air jet mill, a hammer mill, a force mill, a stone mill, or a freeze pulverizer.

[0283] The resulting fluororesin composition may be granulated, thereby obtaining a fluororesin composition having a higher apparent density and better handleability. The granulation method may be any known method, such as underwater granulation, hot water granulation, emulsion dispersion granulation, emulsion hot water granulation, solventless granulation, or dry solvent granulation.

[0284] The first fluororesin composition of the present disclosure is also preferably a fluororesin composition (also referred to as fluororesin composition (3a)) that contains a fluororesin A that does not exhibit melt fluidity and has a history of being heated to a temperature equal to or higher than its melting point, a fluororesin B3 that does not exhibit melt fluidity and has been polymerized by emulsion polymerization and has no history of being heated to a temperature equal to or higher than its melting point, and a filler, and has an apparent density of 0.42 g / ml or more. The fluororesin composition (3a) contains a fluororesin B3 polymerized by emulsion polymerization that has no history of being heated to a temperature equal to or higher than its melting point, and has an apparent density within a specific range. Therefore, despite containing a fluororesin A that has a history of being heated to a temperature equal to or higher than its melting point, the composition has excellent handleability (e.g., handleability during transportation and compression molding). Furthermore, the fluororesin composition (3a) has good tensile properties (for example, tensile strength at break, tensile strain at break).

[0285] The fluororesin composition (3a) preferably has one or more melting points in the temperature range below 333°C and one or more melting points in the temperature range of 333 to 360°C. The temperature range of less than 333°C is more preferably less than 332°C, even more preferably less than 331°C, and is preferably 100°C or higher, more preferably 140°C or higher, and even more preferably 160°C or higher. The temperature range of 333 to 360°C is more preferably 334°C or higher, even more preferably 335°C, and is more preferably 355°C or lower, even more preferably 350°C or lower. Having melting points in the above two temperature ranges means that the fluororesin composition contains fluororesin A, which has a history of being heated to a temperature equal to or higher than its melting point and does not exhibit melt flowability, and fluororesin B3, which has no history of being heated to a temperature equal to or higher than its melting point and does not exhibit melt flowability.

[0286] As the fluororesin A and the filler in the fluororesin composition (3a), those mentioned above can be used.

[0287] The fluororesin B3 has no history of being heated to a temperature equal to or higher than its melting point.

[0288] The fluororesin B3 preferably has a melting point of 100 to 360° C. The melting point is more preferably 140° C. or higher, and even more preferably 160° C. or higher, and is more preferably 355° C. or lower, and even more preferably 350° C. or lower.

[0289] The fluororesin B3 preferably has one or more melting points in the temperature range of 333 to 360° C. The temperature range is more preferably 334° C. or higher, and even more preferably 335° C. or higher, and is more preferably 355° C. or lower, and even more preferably 350° C. or lower. The fact that the melting point is within the above range indicates that there is no history of heating to a temperature equal to or higher than the melting point. In addition to the above melting point, the material may also have a melting point in a temperature range below 333°C.

[0290] Fluorine resin B3 does not exhibit melt fluidity, as described above.

[0291] The fluororesin B3 is preferably PTFE, which may be a high molecular weight PTFE.

[0292] The PTFE (high molecular weight PTFE) as the fluororesin B3 preferably exhibits at least one endothermic peak in the range of 333 to 347°C in a heat of fusion curve when heated at a rate of 10°C / min using a differential scanning calorimeter (DSC), and the heat of fusion between 290 and 350°C calculated from the heat of fusion curve is 62 mJ / mg or more.

[0293] The PTFE as the fluororesin B3 preferably has a standard specific gravity (SSG) of 2.130 to 2.280. The standard specific gravity is measured by the water displacement method in accordance with ASTM D 792 using a sample molded in accordance with ASTM D4895 89. The term "high molecular weight" for PTFE that has not been heated to a temperature equal to or higher than its melting point means that the standard specific gravity is within the above range.

[0294] The PTFE used as the fluororesin B3 generally has non-melt secondary processability, as described above.

[0295] The PTFE as the fluororesin B3 may be a homopolymer of TFE, or a modified PTFE containing 99.0% by mass or more of polymerized units based on TFE and 1.0% by mass or less of polymerized units based on a modifying monomer (modifying monomer units). The modified PTFE may consist only of polymerized units based on TFE and modifying monomer units. Modified PTFE is preferred in that it further improves the handling properties and tensile properties of the fluororesin composition.

[0296] The modified PTFE preferably has a content of the modified monomer unit in the range of 0.00001 to 1.0% by mass relative to the total polymerized units. The lower limit of the content of the modified monomer unit is more preferably 0.0001% by mass, even more preferably 0.001% by mass, even more preferably 0.005% by mass, and especially preferably 0.010% by mass. The upper limit of the content of the modified monomer unit is preferably 0.90% by mass, more preferably 0.50% by mass, even more preferably 0.40% by mass, even more preferably 0.30% by mass, especially preferably 0.20% by mass, and especially preferably 0.10% by mass.

[0297] The modifying monomers that can be used in the above PTFE as the fluororesin B3 are the same as those exemplified for the PTFE (high molecular weight PTFE) as the fluororesin A.

[0298] Fluororesin B3 is polymerized by emulsion polymerization. Fluororesin B3, which is polymerized by emulsion polymerization and does not exhibit melt fluidity, may satisfy any of the following conditions, and preferably satisfies all of them: (i) The proportion of particles (primary particles) having a particle size of 1 μm or less as determined by image processing using a scanning electron microscope (SEM) is more than 50%, preferably more than 70%, and more preferably more than 90%. (ii) The amount of anionic fluorine-containing surfactant measured by liquid chromatography / mass spectrometry (LC / MS / MS) using an extract obtained by Soxhlet extraction with methanol is 1 ppb by mass or more.

[0299] The emulsion polymerization can be carried out by a known method. For example, an aqueous dispersion containing particles (primary particles) of fluororesin B3 can be obtained by emulsion polymerization of monomers necessary for constituting fluororesin B3 in an aqueous medium in the presence of an anionic fluorine-containing surfactant and a polymerization initiator. In the emulsion polymerization, a chain transfer agent, a buffer, a pH adjuster, a stabilizing aid, a dispersion stabilizer, etc. may be used as needed.

[0300] The aqueous dispersion may contain a hydrocarbon surfactant. The hydrocarbon surfactant preferably does not contain a fluorine atom. The hydrocarbon surfactant may be one that was used in the emulsion polymerization, or may be one that was added after the emulsion polymerization.

[0301] Examples of the hydrocarbon surfactant include the compounds exemplified for the fluororesin composition (1).

[0302] The content of the hydrocarbon surfactant is preferably 12% by mass or less, more preferably 8% by mass or less, even more preferably 6% by mass or less, even more preferably 4% by mass or less, particularly preferably 2% by mass or less, and particularly preferably 1% by mass or less, based on the solid content of the aqueous dispersion, from the viewpoint of producing a fluororesin composition with less coloration and more excellent tensile properties. The content of the hydrocarbon surfactant may also be 1 ppm by mass or more, 10 ppm by mass or more, 100 ppm by mass or more, or 500 ppm by mass or more.

[0303] Fluororesin B3 may be provided from the aqueous dispersion. Alternatively, the aqueous dispersion may be coagulated and dried to obtain a powder containing particles of the fluororesin B3. The fluororesin B3 may be obtained from the powder. Both the coagulation and drying can be carried out by known methods.

[0304] The fluororesin composition (3a) may contain particles of the fluororesin B3. The particles of the fluororesin B3 may be primary particles or secondary particles of the fluororesin B3.

[0305] The secondary particles of the fluororesin B3 preferably have an average secondary particle diameter of 1000 μm or less, in order to further improve the handleability of the fluororesin composition. The average secondary particle diameter is more preferably 900 μm or less, even more preferably 800 μm or less, and particularly preferably 700 μm or less. The average secondary particle diameter is also preferably 100 μm or more, more preferably 200 μm or more, even more preferably 300 μm or more, and particularly preferably 400 μm or more. The above average secondary particle diameter is measured using a Beckman Coulter laser diffraction particle size distribution analyzer (LS13 320) in a dry state at a vacuum pressure of 20 mH2O, and is equal to the particle diameter corresponding to 50% of the integrated particle size distribution (volume basis).

[0306] In order to further improve the handleability of the fluororesin composition, the particles of fluororesin B3 preferably have a D90 of 10 μm or more, more preferably 30 μm or more, and even more preferably 50 μm or more, and preferably have a D90 of 2000 μm or less, more preferably 1500 μm or less, and even more preferably 1200 μm or less. The above D90 is measured using a Beckman Coulter laser diffraction particle size analyzer (LS13 320) in a dry state at a vacuum pressure of 20 mH2O, and is equal to the particle diameter corresponding to 90% of the integrated particle size distribution (volume basis).

[0307] The fluororesin composition (3a) has an apparent density of 0.42 g / ml or more. When the apparent density is within the above range, the fluororesin composition (3a) has excellent handleability. In terms of easier handling, the apparent density is preferably 0.45 g / ml or more, and more preferably 0.47 g / ml or more. There is no particular upper limit, but it may be 1.00 g / ml. The apparent density is measured in accordance with JIS K 6891.

[0308] The content of fluororesin A in the fluororesin composition (3a) is preferably 10 to 90% by mass relative to the fluororesin composition, in order to further improve the tensile properties. The content is more preferably 20% by mass or more, even more preferably 30% by mass or more, even more preferably 40% by mass or more, especially preferably 50% by mass or more, particularly preferably more than 50% by mass, and more preferably 85% by mass or less, even more preferably 80% by mass or less, even more preferably less than 80% by mass, especially preferably 75% by mass or less, and especially preferably 70% by mass or less.

[0309] The content of fluororesin B3 in the fluororesin composition (3a) is preferably 10 to 90% by mass relative to the fluororesin composition, in order to further improve the tensile properties. The content is more preferably 15% by mass or more, even more preferably 20% by mass or more, even more preferably more than 20% by mass, especially preferably 25% by mass or more, and particularly preferably 30% by mass or more, and is more preferably 80% by mass or less, even more preferably 70% by mass or less, even more preferably 60% by mass or less, especially preferably 50% by mass or less, and particularly preferably less than 50% by mass.

[0310] The total amount of fluororesins A and B3 in the fluororesin composition (3a) is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 98% by mass or more, based on the fluororesin composition.

[0311] The fluororesin composition (3a) contains TFE units and modified monomer units derived from a modified monomer copolymerizable with TFE, and the amount of the modified monomer units is preferably 1.0 mass% or less relative to the total polymerized units, and the amount of TFE units is preferably 99.0 mass% or more.

[0312] The lower limit of the content of the modified monomer unit in the fluororesin composition (3a) may be 0% by mass, more preferably 0.0001% by mass, even more preferably 0.001% by mass, even more preferably 0.005% by mass, and particularly preferably 0.010% by mass. The upper limit of the content of the modified monomer unit is preferably 0.90% by mass, more preferably 0.50% by mass, even more preferably 0.40% by mass, even more preferably 0.30% by mass, especially preferably 0.20% by mass, and particularly preferably 0.10% by mass. The content of the modified monomer unit can be calculated by appropriately combining NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer. In addition, if the raw material composition is known, it can also be calculated from the raw material composition.

[0313] The present disclosure also preferably relates to a fluororesin composition (also referred to as fluororesin composition (3b)) comprising: a fluororesin A that does not exhibit melt fluidity and has a history of being heated to a temperature equal to or higher than its melting point; a fluororesin B3 that does not exhibit melt fluidity and has been polymerized by emulsion polymerization and has no history of being heated to a temperature equal to or higher than its melting point; and a filler, the fluororesin composition comprising TFE units and modified monomer units based on a modified monomer copolymerizable with TFE. The fluororesin composition (3b) has a specific monomer composition and therefore has excellent handleability (e.g., handleability during transportation and compression molding) despite containing the fluororesin A that has a history of being heated to a temperature equal to or higher than the melting point. In addition, the fluororesin composition (3b) has good tensile properties (for example, tensile strength at break, tensile strain at break).

[0314] The fluororesin composition (3b) preferably has one or more melting points in the temperature range below 333°C and one or more melting points in the temperature range of 333 to 360°C. The temperature range of less than 333°C is more preferably less than 332°C, even more preferably less than 331°C, and is preferably 100°C or higher, more preferably 140°C or higher, and even more preferably 160°C or higher. The temperature range of 333 to 360°C is more preferably 334°C or higher, even more preferably 335°C, and is more preferably 355°C or lower, even more preferably 350°C or lower. Having melting points in the above two temperature ranges means that the fluororesin composition contains fluororesin A, which has a history of being heated to a temperature equal to or higher than its melting point and does not exhibit melt flowability, and fluororesin B3, which has no history of being heated to a temperature equal to or higher than its melting point and does not exhibit melt flowability.

[0315] As the fluororesin A in the fluororesin composition (3b), the same fluororesin A as in the fluororesin composition (3a) can be used.

[0316] The fluororesin B3 in the fluororesin composition (3b) may be the same as the fluororesin B3 in the fluororesin composition (3a), and is preferably a modified PTFE containing 99.0% by mass or more of polymerized units based on TFE (TFE units) and 1.0% by mass or less of polymerized units based on a modified monomer (modified monomer units). The fluororesin B3 may consist only of TFE units and modified monomer units. The modifying monomer may be the same as the monomer described above for the modified PTFE as the fluororesin B3 in the fluororesin composition (3a). The preferred range of the content of the modifying monomer unit is the same as the range described for the fluororesin composition (3a).

[0317] The constitution of the fluororesin B3 in the fluororesin composition (3b) other than the composition is the same as that of the fluororesin B3 in the fluororesin composition (3a).

[0318] The fluororesin composition (3b) contains TFE units and modified monomer units based on a modified monomer copolymerizable with TFE. The fluororesin composition (3b) may contain only TFE units and modified monomer units as polymerized units.

[0319] In order to further improve the handleability and tensile properties of the fluororesin composition, the content of the modified monomer unit is preferably 1.0 mass% or less based on the total polymerized units constituting the fluororesin composition. The lower limit of the content of the modified monomer unit is preferably 0.00001 mass%, more preferably 0.0001 mass%, even more preferably 0.001 mass%, even more preferably 0.005 mass%, and particularly preferably 0.010 mass%. The upper limit of the content of the modified monomer unit is preferably 0.90 mass%, more preferably 0.50 mass%, even more preferably 0.40 mass%, even more preferably 0.30 mass%, even more preferably 0.20 mass%, and particularly preferably 0.10 mass%.

[0320] The fluororesin composition (3b) preferably contains TFE units in an amount of 99.0 mass % or more based on the total polymerized units.

[0321] The content of the polymerized units constituting the fluororesin composition (3b) can be calculated by appropriately combining NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer. In addition, when the raw material composition is known, it can also be determined by calculation from the raw material composition.

[0322] The contents of the fluororesins A and B3 in the fluororesin composition (3b), and the total amount of the fluororesins A and B3 are the same as those described for the fluororesin composition (3a).

[0323] The fluororesin composition (3b) preferably has an apparent density of 0.42 g / ml or more, more preferably 0.45 g / ml or more, and even more preferably 0.47 g / ml or more, in terms of easier handling. The upper limit is not particularly limited, but may be 1.00 g / ml. The apparent density is measured in accordance with JIS K 6891.

[0324] The form of the fluororesin compositions (3a) and (3b) is not particularly limited, but it is preferable that they are in the form of powder.

[0325] The fluororesin compositions (3a) and (3b) may satisfy any one of the following conditions, and preferably satisfy all of them. (i) The proportion of particles (primary particles) having a particle size of 1 μm or less as determined by image processing using a scanning electron microscope (SEM) is more than 50%, preferably more than 70%, and more preferably more than 90%. (ii) The amount of anionic fluorine-containing surfactant measured by liquid chromatography / mass spectrometry (LC / MS / MS) using an extract obtained by Soxhlet extraction with methanol is 1 ppb by mass or more.

[0326] The fluororesin compositions (3a) and (3b) preferably have an angle of repose of less than 40°, more preferably less than 38°, and even more preferably less than 35°, in order to have excellent fluidity and easier handling. The above angle of repose is a value obtained by placing a funnel with a total height of 115 mm, a foot diameter of φ26 mm, a foot length of 35 mm, and an intake opening of 60° so that the height from the bottom of the funnel to the sample drop surface is 100 mm, dropping 40 g of sample from the funnel, and measuring the angle of the lower half of the peak of the dropped sample with a protractor.

[0327] The fluororesin compositions (3a) and (3b) preferably have an average secondary particle size of 50 to 500 μm, more preferably 70 μm or more, and even more preferably 100 μm or more, and more preferably 300 μm or less, and even more preferably 200 μm or less. The above average secondary particle diameter is measured using a Beckman Coulter laser diffraction particle size distribution analyzer (LS13 320) in a dry state at a vacuum pressure of 20 mH2O, and is equal to the particle diameter corresponding to 50% of the integrated particle size distribution (volume basis).

[0328] The fluororesin compositions (3a) and (3b) preferably have a D90 of 10 μm or more, more preferably 30 μm or more, even more preferably 50 μm or more, and particularly preferably 100 μm or more, and preferably 800 μm or less, more preferably 600 μm or less, and even more preferably 500 μm or less. The above D90 is measured using a Beckman Coulter laser diffraction particle size analyzer (LS13 320) in a dry state at a vacuum pressure of 20 mH2O, and is equal to the particle diameter corresponding to 90% of the integrated particle size distribution (volume basis).

[0329] In the fluororesin compositions (3a) and (3b), the content (total amount) of low-molecular-weight fluorine-containing compounds is preferably 1 ppm by mass or less, more preferably 500 ppb by mass or less, even more preferably 100 ppb by mass or less, even more preferably 50 ppb by mass or less, especially preferably 25 ppb by mass or less, particularly preferably 10 ppb by mass or less, especially more preferably 5 ppb by mass or less, especially especially preferably 1 ppb by mass or less, and most preferably less than 1 ppb by mass, in order to further improve the tensile properties of the fluororesin compositions. The content of the low-molecular-weight fluorine-containing compound is measured by subjecting a sample to Soxhlet extraction with methanol and then using a liquid chromatograph mass meter (LC / MS / MS).

[0330] Examples of the low molecular weight fluorine-containing compound include the compounds exemplified for the fluororesin composition (1).

[0331] The fluororesin compositions (3a) and (3b) can be produced, for example, by mixing powder of the fluororesin A, particles of the fluororesin B3, and a filler.

[0332] The particles of fluororesin B3 may be mixed with the powder of fluororesin A in the form of a powder, or may be mixed with the powder of fluororesin A in the form of an aqueous dispersion. However, mixing with the powder of fluororesin A in the form of a powder is preferred, as this will result in a fluororesin composition that is even more excellent in handleability and tensile properties.

[0333] The mixing can be carried out using, for example, a grinder equipped with a rotary blade, such as Wonder Crusher WC-3 manufactured by Osaka Chemical Co., Ltd. When mixing using the above-mentioned pulverizer, the blade rotation speed is preferably set to 1500 to 10,000 rpm. By setting the rotation speed within the above range, the shear force during mixing can be reduced and fibrous formation of the fluororesin B3 can be suppressed, resulting in a fluororesin composition with a high apparent density and excellent handleability. When the fluororesin B3 is a TFE homopolymer, the rotation speed is preferably set to 1500 to 2500 rpm.

[0334] Furthermore, a fluororesin composition having a high apparent density and excellent handleability can also be obtained by granulating the fluororesin composition after mixing. In this embodiment, the mixing may be carried out under conditions that make the fluororesin B3 prone to fibrous formation. The granulation method may be any known method, such as underwater granulation, hot water granulation, emulsion dispersion granulation, emulsion hot water granulation, solventless granulation, or dry solvent granulation.

[0335] The resulting fluororesin composition may be pulverized by a known method, for example, using a pulverizer such as an air jet mill, a hammer mill, a force mill, a stone mill, or a freeze pulverizer.

[0336] The first fluororesin composition of the present disclosure is also preferably a fluororesin composition (also referred to as fluororesin composition (4)) that contains a fluororesin A that has a history of being heated to a temperature equal to or higher than its melting point and does not exhibit melt flowability, a fluororesin B4 that has no history of being heated to a temperature equal to or higher than its melting point and does not exhibit melt flowability, and a filler, and that contains tetrafluoroethylene (TFE) units and modified monomer units based on a modified monomer copolymerizable with TFE. The fluororesin composition (4) has a specific monomer composition and therefore has excellent handleability (e.g., handleability during transportation and compression molding) despite containing the fluororesin A that has a history of being heated to a temperature above the melting point. The fluororesin composition (4) also has excellent tensile properties (for example, tensile strength at break and tensile strain at break).

[0337] The fluororesin composition (4) preferably has one or more melting points in the temperature range below 333°C and one or more melting points in the temperature range of 333 to 360°C. The temperature range of less than 333°C is more preferably less than 332°C, even more preferably less than 331°C, and is preferably 100°C or higher, more preferably 140°C or higher, and even more preferably 160°C or higher. The temperature range of 333 to 360°C is more preferably 334°C or higher, even more preferably 335°C, and is more preferably 355°C or lower, even more preferably 350°C or lower. Having melting points in the above two temperature ranges means that the fluororesin composition contains fluororesin A, which has a history of being heated to a temperature equal to or higher than its melting point and does not exhibit melt flowability, and fluororesin B4, which has no history of being heated to a temperature equal to or higher than its melting point and does not exhibit melt flowability.

[0338] As the fluororesin A and the filler in the fluororesin composition (4), those mentioned above can be used.

[0339] Fluororesin B4 has no history of being heated to a temperature equal to or higher than its melting point.

[0340] The fluororesin B4 preferably has a melting point of 100 to 360° C. The melting point is more preferably 140° C. or higher, and even more preferably 160° C. or higher, and is more preferably 355° C. or lower, and even more preferably 350° C. or lower.

[0341] The fluororesin B4 preferably has one or more melting points in the temperature range of 333 to 360° C. The temperature range is more preferably 334° C. or higher, and even more preferably 335° C. or higher, and is more preferably 355° C. or lower, and even more preferably 350° C. or lower. The fact that the melting point is within the above range indicates that there is no history of heating to a temperature equal to or higher than the melting point. In addition to the above melting point, the material may also have a melting point in a temperature range below 333°C.

[0342] Fluororesin B4 does not exhibit melt fluidity, as described above.

[0343] The fluororesin B4 is preferably PTFE, which may be a high molecular weight PTFE.

[0344] The PTFE (high molecular weight PTFE) as fluororesin B4 preferably exhibits at least one endothermic peak in the range of 333 to 347°C in a heat of fusion curve when heated at a rate of 10°C / min using a differential scanning calorimeter (DSC), and the heat of fusion between 290 and 350°C calculated from the heat of fusion curve is 62 mJ / mg or more.

[0345] The PTFE as the fluororesin B4 preferably has a standard specific gravity (SSG) of 2.130 to 2.280. The standard specific gravity is measured by the water displacement method in accordance with ASTM D 792 using a sample molded in accordance with ASTM D4895 89. The term "high molecular weight" for PTFE that has not been heated to a temperature equal to or higher than its melting point means that the standard specific gravity is within the above range.

[0346] The PTFE used as the fluororesin B4 generally has non-melt secondary processability, as described above.

[0347] The PTFE as the fluororesin B4 is preferably a modified PTFE containing 99.0% by mass or more of polymerization units based on TFE and 1.0% by mass or less of polymerization units based on a modifying monomer (modifying monomer units), in that it can provide a fluororesin composition having a higher apparent density and better handleability, and a fluororesin composition having better tensile properties. The modified PTFE may consist only of polymerization units based on TFE and modifying monomer units.

[0348] The modified PTFE preferably has a content of the modified monomer unit in the range of 0.00001 to 1.0% by mass relative to the total polymerized units. The lower limit of the content of the modified monomer unit is more preferably 0.0001% by mass, even more preferably 0.001% by mass, even more preferably 0.005% by mass, and especially preferably 0.010% by mass. The upper limit of the content of the modified monomer unit is preferably 0.90% by mass, more preferably 0.50% by mass, even more preferably 0.40% by mass, even more preferably 0.30% by mass, especially preferably 0.20% by mass, and especially preferably 0.10% by mass.

[0349] The modifying monomers that can be used in the above PTFE as the fluororesin B4 are the same as those exemplified for the PTFE (high molecular weight PTFE) as the fluororesin A.

[0350] The fluororesin B4 can be produced by suspension polymerization or emulsion polymerization.

[0351] The suspension polymerization can be carried out by a known method. For example, a polymerization initiator is dispersed in an aqueous medium without using an anionic fluorinated surfactant or with a limited amount of anionic fluorinated surfactant, and the monomers necessary for constituting the fluororesin B4 are polymerized to directly isolate a granular powder of the fluororesin B4.

[0352] As the fluororesin B4, a powder obtained directly by the above suspension polymerization may be used, or a powder obtained by pulverizing and / or granulating the above powder may be used. The above-mentioned pulverization may be carried out by a known method, and can be carried out by a pulverization method using a pulverizer such as a hammer mill, a pin mill, a jet mill, or a cutter mill. The granulation may be carried out by a known method such as underwater granulation, hot water granulation, emulsion dispersion granulation, emulsion hot water granulation, solventless granulation, or dry solvent granulation.

[0353] The emulsion polymerization can be carried out by a known method. For example, an aqueous dispersion containing particles (primary particles) of fluororesin B4 can be obtained by emulsion polymerization of monomers necessary for constituting fluororesin B4 in an aqueous medium in the presence of an anionic fluorine-containing surfactant and a polymerization initiator. In the emulsion polymerization, a chain transfer agent, a buffer, a pH adjuster, a stabilizing aid, a dispersion stabilizer, etc. may be used as needed.

[0354] The aqueous dispersion may contain a hydrocarbon surfactant. The hydrocarbon surfactant preferably does not contain a fluorine atom. The hydrocarbon surfactant may be one that was used in the emulsion polymerization, or may be one that was added after the emulsion polymerization.

[0355] Examples of the hydrocarbon surfactant include the compounds exemplified for the fluororesin composition (1).

[0356] The content of the hydrocarbon surfactant is preferably 12% by mass or less, more preferably 8% by mass or less, even more preferably 6% by mass or less, even more preferably 4% by mass or less, particularly preferably 2% by mass or less, and particularly preferably 1% by mass or less, based on the solid content of the aqueous dispersion, from the viewpoint of producing a fluororesin composition with less coloration and more excellent tensile properties. The content of the hydrocarbon surfactant may also be 1 ppm by mass or more, 10 ppm by mass or more, 100 ppm by mass or more, or 500 ppm by mass or more.

[0357] Fluororesin B4 may be provided from the aqueous dispersion. Alternatively, the aqueous dispersion may be coagulated and dried to obtain a powder containing particles of the fluororesin B4. The fluororesin B4 may be obtained from the powder. Both the coagulation and drying can be carried out by known methods.

[0358] The fluororesin composition (4) may contain particles of the fluororesin B4. The particles of the fluororesin B4 may be secondary particles of the fluororesin B4.

[0359] The particles of the fluororesin B4 preferably have an average secondary particle diameter of 1 to 1000 μm. The average secondary particle diameter is more preferably 5 μm or more, even more preferably 10 μm or more, and even more preferably 20 μm or more. It is also more preferably 900 μm or less, even more preferably 800 μm or less, and even more preferably 700 μm or less. The above average secondary particle diameter is measured using a Beckman Coulter laser diffraction particle size distribution analyzer (LS13 320) in a dry state at a vacuum pressure of 20 mH2O, and is equal to the particle diameter corresponding to 50% of the integrated particle size distribution (volume basis).

[0360] The particles of the fluororesin B4 preferably have a D90 of 10 μm or more, more preferably 30 μm or more, and even more preferably 50 μm or more, and preferably 2000 μm or less, more preferably 1500 μm or less, and even more preferably 1200 μm or less. The above D90 is measured using a Beckman Coulter laser diffraction particle size analyzer (LS13 320) in a dry state at a vacuum pressure of 20 mH2O, and is equal to the particle diameter corresponding to 90% of the integrated particle size distribution (volume basis).

[0361] The fluororesin composition (4) contains TFE units and modified monomer units based on a modified monomer copolymerizable with TFE. The fluororesin composition (4) may contain only TFE units and modified monomer units as polymerized units.

[0362] In order to further improve handleability and tensile properties, the content of the modified monomer unit is preferably 1.0 mass% or less based on the total polymerized units constituting the fluororesin composition. The lower limit of the content of the modified monomer unit is preferably 0.00001 mass%, more preferably 0.0001 mass%, even more preferably 0.001 mass%, even more preferably 0.005 mass%, and especially preferably 0.010 mass%. The upper limit of the content of the modified monomer unit is preferably 0.90 mass%, more preferably 0.50 mass%, even more preferably 0.40 mass%, even more preferably 0.30 mass%, even more preferably 0.20 mass%, and especially preferably 0.10 mass%.

[0363] The fluororesin composition (4) preferably contains 99.0 mass % or more of TFE units based on all polymerized units.

[0364] The content of the polymerized units constituting the fluororesin composition (4) can be calculated by an appropriate combination of NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer. In addition, when the raw material composition is known, it can also be determined by calculation from the raw material composition.

[0365] In order to achieve better handling properties, the fluororesin composition (4) preferably has an apparent density of 0.40 g / ml or more, more preferably 0.42 g / ml or more, even more preferably 0.45 g / ml or more, and particularly preferably 0.47 g / ml or more. There is no particular upper limit, but it may be 1.00 g / ml. The apparent density is measured in accordance with JIS K 6891.

[0366] The content of fluororesin A in fluororesin composition (4) is preferably 10 to 90% by mass relative to the fluororesin composition, in order to further improve tensile properties. The content is more preferably 20% by mass or more, even more preferably 30% by mass or more, even more preferably 40% by mass or more, and particularly preferably 50% by mass or more, and is more preferably 85% by mass or less, even more preferably 80% by mass or less, even more preferably less than 80% by mass, especially preferably 75% by mass or less, and particularly preferably 70% by mass or less.

[0367] The content of fluororesin B4 in fluororesin composition (4) is preferably 10 to 90% by mass relative to the fluororesin composition, in order to further improve tensile properties. The content is more preferably 15% by mass or more, even more preferably 20% by mass or more, even more preferably more than 20% by mass, particularly preferably 25% by mass or more, and particularly preferably 30% by mass or more, and is more preferably 80% by mass or less, even more preferably 70% by mass or less, even more preferably 60% by mass or less, and particularly preferably 50% by mass or less.

[0368] The total amount of fluororesins A and B4 in the fluororesin composition (4) is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 98% by mass or more, based on the fluororesin composition.

[0369] The form of the fluororesin composition (4) is not particularly limited, but it is preferably in the form of a powder.

[0370] In the fluororesin composition (4), the maximum linear length of the particles of fluororesin A is preferably smaller than the maximum linear length of the particles of fluororesin B4. When the maximum linear lengths of the particles of fluororesins A and B4 satisfy the above relationship, the apparent density of the fluororesin composition can be increased, further improving handleability. In addition, since there is no need to perform a deformation treatment to increase the maximum linear length of the particles of fluororesin A, the production cost of the fluororesin composition can be reduced. The above embodiment is particularly suitable when the fluororesin B4 is obtained by suspension polymerization.

[0371] The fluororesin composition (4) preferably has an angle of repose of less than 40°, more preferably less than 38°, and even more preferably less than 35°, in order to have excellent fluidity and easier handling. The above angle of repose is a value obtained by placing a funnel with a total height of 115 mm, a foot diameter of φ26 mm, a foot length of 35 mm, and an intake opening of 60° so that the height from the bottom of the funnel to the sample drop surface is 100 mm, dropping 40 g of sample from the funnel, and measuring the angle of the lower half of the peak of the dropped sample with a protractor.

[0372] The fluororesin composition (4) preferably has an average secondary particle diameter of 5 to 700 μm, more preferably 10 μm or more, even more preferably 20 μm or more, and more preferably 600 μm or less, even more preferably 500 μm or less, particularly preferably 400 μm or less. The above average secondary particle diameter is measured using a Beckman Coulter laser diffraction particle size distribution analyzer (LS13 320) in a dry state at a vacuum pressure of 20 mH2O, and is equal to the particle diameter corresponding to 50% of the integrated particle size distribution (volume basis).

[0373] The fluororesin composition (4) preferably has a D90 of 10 μm or more, more preferably 30 μm or more, and even more preferably 50 μm or more, and preferably 600 μm or less, more preferably 500 μm or less, and even more preferably 400 μm or less. The above D90 is measured using a Beckman Coulter laser diffraction particle size analyzer (LS13 320) in a dry state at a vacuum pressure of 20 mH2O, and is equal to the particle diameter corresponding to 90% of the integrated particle size distribution (volume basis).

[0374] In order to further improve the tensile properties of the fluororesin composition (4), the content (total amount) of low-molecular-weight fluorine-containing compounds is preferably 1 ppm by mass or less, more preferably 500 ppb by mass or less, even more preferably 100 ppb by mass or less, even more preferably 50 ppb by mass or less, especially preferably 25 ppb by mass or less, particularly preferably 10 ppb by mass or less, especially more preferably 5 ppb by mass or less, especially especially preferably 1 ppb by mass or less, and most preferably less than 1 ppb by mass, relative to the fluororesin composition. The content of the low-molecular-weight fluorine-containing compound is measured by subjecting a sample to Soxhlet extraction with methanol and then using a liquid chromatograph mass meter (LC / MS / MS).

[0375] Examples of the low molecular weight fluorine-containing compound include the compounds exemplified for the fluororesin composition (1).

[0376] The fluororesin composition (4) can be produced, for example, by mixing powder of the fluororesin A, particles of the fluororesin B4, and a filler.

[0377] When the particles of the fluororesin B4 are obtained by suspension polymerization, they are preferably mixed in the form of a powder with the powder of the fluororesin A. The mixing method is not particularly limited, and known methods can be used. Mixing can also be carried out in a pulverizer. In order to easily obtain a fluororesin composition having a higher apparent density and better handleability, it is preferable that the maximum linear length of the particles of fluororesin A is smaller than the maximum linear length of the particles of fluororesin B4.

[0378] Furthermore, when the particles of fluororesin B4 are obtained by emulsion polymerization, they may be mixed in the form of a powder with the powder of fluororesin A, or in the form of an aqueous dispersion. However, mixing in the form of a powder with the powder of fluororesin A is preferred, as this will result in a fluororesin composition that is even more excellent in handleability and tensile properties.

[0379] The mixing can be carried out using, for example, a grinder equipped with a rotary blade, such as Wonder Crusher WC-3 manufactured by Osaka Chemical Co., Ltd. When mixing using the above-mentioned grinder, the blade rotation speed is preferably set to 1500 to 10000 rpm. By setting the rotation speed within this range, the shear force during mixing can be reduced and fibrous formation of the fluororesin B4 can be suppressed, resulting in a fluororesin composition with a high apparent density and excellent handleability.

[0380] Furthermore, a fluororesin composition having a high apparent density and excellent handleability can also be obtained by granulating the fluororesin composition after mixing. In this embodiment, the mixing may be carried out under conditions that make the fluororesin B4 prone to fibrous formation. The granulation method may be any known method, such as underwater granulation, hot water granulation, emulsion dispersion granulation, emulsion hot water granulation, solventless granulation, or dry solvent granulation.

[0381] The resulting fluororesin composition may be pulverized by a known method, for example, using a pulverizer such as an air jet mill, a hammer mill, a force mill, a stone mill, or a freeze pulverizer.

[0382] The first fluororesin composition of the present disclosure is preferably a fluororesin composition containing fluororesin A that has a history of being heated to a temperature equal to or higher than its melting point and does not exhibit melt fluidity, fluororesin B5 that has no history of being heated to a temperature equal to or higher than its melting point, and a filler, and also preferably a fluororesin composition containing fine particles having a primary particle size of 1 μm or less (also referred to as fluororesin composition (5)). The fluororesin composition (5) contains a fluororesin that has not been heated to a temperature equal to or higher than its melting point, and also contains fine particles having a specific particle size. Therefore, despite containing a fluororesin that has been heated to a temperature equal to or higher than its melting point, the composition has little coloring and excellent tensile properties.

[0383] The fluororesin composition (5) preferably has one or more melting points in the temperature range below 333°C and one or more melting points in the temperature range of 333°C or higher. The temperature range of less than 333°C is more preferably less than 332°C, even more preferably less than 331°C, and is preferably 100°C or higher, more preferably 140°C or higher, and even more preferably 160°C or higher. The temperature range of 333°C or higher is more preferably 334°C or higher, and even more preferably 335°C, and is preferably 360°C or lower, more preferably 355°C or lower, and even more preferably 350°C or lower. Having melting points in the above two temperature ranges indicates that the fluororesin composition contains a fluororesin A (preferably PTFE) that does not exhibit melt flowability and has a history of being heated to a temperature equal to or higher than its melting point, and a fluororesin B5 (preferably a fluororesin that does not exhibit melt flowability, more preferably PTFE) that does not have a history of being heated to a temperature equal to or higher than its melting point.

[0384] As the fluororesin A and the filler in the fluororesin composition (5), those mentioned above can be used.

[0385] Fluororesin B5 has no history of being heated to a temperature equal to or higher than its melting point.

[0386] The fluororesin B5 preferably has a melting point of 100 to 360° C. The melting point is more preferably 140° C. or higher, and even more preferably 160° C. or higher, and is more preferably 355° C. or lower, and even more preferably 350° C. or lower.

[0387] The fluororesin B5 preferably has one or more melting points in the temperature range of 333 to 360° C. The temperature range is more preferably 334° C. or higher, and even more preferably 335° C. or higher, and is more preferably 355° C. or lower, and even more preferably 350° C. or lower. The fact that the melting point is within the above range indicates that the fluororesin B5 (preferably a fluororesin that does not exhibit melt flowability, more preferably PTFE) has no history of being heated to a temperature equal to or higher than the melting point. In addition to the above melting point, the material may also have a melting point in a temperature range below 333°C.

[0388] Examples of fluororesin B5 include PTFE, PFA, FEP, ETFE, EFEP, PCTFE, CTFE / TFE copolymer, CTFE / TFE / PAVE copolymer, Et / CTFE copolymer, PVF, PVdF, VdF / TFE copolymer, VdF / HFP copolymer, VdF / TFE / HFP copolymer, VdF / HFP / (meth)acrylic acid copolymer, VdF / CTFE copolymer, VdF / pentafluoropropylene copolymer, VdF / PAVE / TFE copolymer, and low molecular weight PTFE.

[0389] The PTFE used as the fluororesin B5 does not exhibit melt flowability. The PTFE may be a high-molecular-weight PTFE.

[0390] The PTFE (high molecular weight PTFE) as fluororesin B5 preferably exhibits at least one endothermic peak in the range of 333 to 347°C in a heat of fusion curve when heated at a rate of 10°C / min using a differential scanning calorimeter (DSC), and the heat of fusion between 290 and 350°C calculated from the heat of fusion curve is 62 mJ / mg or more.

[0391] The PTFE as the fluororesin B5 preferably has a standard specific gravity (SSG) of 2.130 to 2.280. The standard specific gravity is measured by the water displacement method in accordance with ASTM D 792 using a sample molded in accordance with ASTM D4895 89. The term "high molecular weight" for PTFE that has not been heated to a temperature equal to or higher than its melting point means that the standard specific gravity is within the above range.

[0392] The PTFE used as the fluororesin B5 generally has non-melt secondary processability, as described above.

[0393] The PTFE as the fluororesin B5 may be a homopolymer of TFE, or a modified PTFE containing 99.0% by mass or more of polymerized units based on TFE and 1.0% by mass or less of polymerized units based on a modified monomer (modified monomer units). The modified PTFE may consist only of polymerized units based on TFE and modified monomer units.

[0394] The modified PTFE preferably has a content of the modified monomer unit in the range of 0.00001 to 1.0% by mass relative to the total polymerized units. The lower limit of the content of the modified monomer unit is more preferably 0.0001% by mass, even more preferably 0.001% by mass, even more preferably 0.005% by mass, and especially preferably 0.010% by mass. The upper limit of the content of the modified monomer unit is preferably 0.90% by mass, more preferably 0.50% by mass, even more preferably 0.40% by mass, even more preferably 0.30% by mass, especially preferably 0.20% by mass, and especially preferably 0.10% by mass.

[0395] The modifying monomers that can be used in the above PTFE as the fluororesin B5 are the same as those exemplified for the PTFE (high molecular weight PTFE) as the fluororesin A.

[0396] The low-molecular-weight PTFE as the fluororesin B5 exhibits melt fluidity. The low-molecular-weight PTFE has a melt viscosity (complex viscosity) of 1.0×10 at 380°C. 1 ~1.0×10 7 The melt viscosity is 1.0×10 Pa·s. 2 It is preferable that the value is 1.5×10 or more. 3 Pa·s or more is more preferable, and 7.0×10 3 It is more preferable that the viscosity is 7.0×10 Pa·s or more. 5 Preferably, it is 3.0 x 10 or less. 5 Pa·s or less is more preferable, and 1.0×10 5 It is more preferably Pa·s or less. In this specification, "low molecular weight PTFE" means PTFE having the melt viscosity within the above range.

[0397] The melt viscosity was measured in accordance with ASTM D 1238 using a flow tester (manufactured by Shimadzu Corporation) and a 2φ-8L die, with a 2g sample preheated at 380°C for 5 minutes and maintained at the temperature under a load of 0.7 MPa.

[0398] The low-molecular-weight PTFE as fluororesin B5 preferably has a melting point of 320 to 340° C. The melting point is more preferably 324° C. or higher, more preferably 336° C. or lower, even more preferably 333° C. or lower, even more preferably 332° C. or lower, particularly preferably 331° C. or lower, and particularly preferably 330° C. or lower.

[0399] The low-molecular-weight PTFE as fluororesin B5 may be a TFE homopolymer, or a modified PTFE containing 99.0% by mass or more of polymerized units based on TFE and 1.0% by mass or less of polymerized units based on a modified monomer (modified monomer units). The modified PTFE may consist only of polymerized units based on TFE and modified monomer units.

[0400] The modified PTFE preferably has a content of the modified monomer unit in the range of 0.00001 to 1.0% by mass relative to the total polymerized units. The lower limit of the content of the modified monomer unit is more preferably 0.0001% by mass, even more preferably 0.001% by mass, even more preferably 0.005% by mass, and especially preferably 0.010% by mass. The upper limit of the content of the modified monomer unit is preferably 0.90% by mass, more preferably 0.50% by mass, even more preferably 0.40% by mass, even more preferably 0.30% by mass, especially preferably 0.20% by mass, and especially preferably 0.10% by mass.

[0401] Modified monomers that can be used in the low molecular weight PTFE as the fluororesin B5 include the monomers mentioned above for the PTFE (high molecular weight PTFE) as the fluororesin that does not exhibit melt flowability.

[0402] The fluororesin B5 may be a fluororesin that does not exhibit melt fluidity, or may be a fluororesin that exhibits melt fluidity. The fluororesin that does not exhibit melt fluidity is preferably the above-mentioned PTFE (high molecular weight PTFE). Examples of the fluororesin exhibiting melt fluidity include the same as the fluororesin B1 described above.

[0403] The fluororesin B5 is preferably a fluororesin that does not exhibit melt flowability, and is more preferably PTFE (high molecular weight PTFE). The fluororesin B5 may be a fluororesin exhibiting melt fluidity, and is preferably at least one selected from the group consisting of PFA, FEP, ETFE, EFEP, PCTFE, CTFE / TFE copolymer, CTFE / TFE / PAVE copolymer, Et / CTFE copolymer, PVF, PVdF, VdF / TFE copolymer, VdF / HFP copolymer, VdF / TFE / HFP copolymer, VdF / HFP / (meth)acrylic acid copolymer, VdF / CTFE copolymer, VdF / pentafluoropropylene copolymer, VdF / PAVE / TFE copolymer, and low-molecular-weight PTFE, more preferably at least one selected from the group consisting of PFA, FEP, and low-molecular-weight PTFE, and even more preferably at least one selected from the group consisting of PFA and FEP.

[0404] The fluororesin composition (5) may contain particles of the fluororesin B5.

[0405] The particles of the fluororesin B5 are preferably primary particles of the fluororesin B5, and the primary particles preferably do not constitute secondary particles.

[0406] The particles of the fluororesin B5 preferably have an average primary particle diameter of 1 μm or less. The average primary particle diameter is more preferably 500 nm or less, even more preferably 450 nm or less, even more preferably 400 nm or less, particularly preferably 350 nm or less, and particularly preferably 300 nm or less. The average primary particle diameter is also preferably 10 nm or more, more preferably 25 nm or more, even more preferably 50 nm or more, even more preferably 100 nm or more, and particularly preferably 150 nm or more. The above average primary particle diameter is the average diameter of 100 or more particles randomly sampled by dropping an aqueous dispersion with a solid content adjusted to 0.5% by mass onto aluminum foil, drying the resulting mixture at 150°C for 1 hour to remove water, and observing the resulting mixture with a scanning electron microscope (SEM). The average primary particle diameter may also be the average value of diameters of 100 or more primary particles randomly sampled when the fluororesin composition is observed under a scanning electron microscope (SEM).

[0407] In one embodiment of the fluororesin composition (5), the particles of the fluororesin B5 preferably have an average aspect ratio of 2.0 or less, more preferably 1.7 or less, even more preferably 1.6 or less, even more preferably 1.5 or less, particularly preferably 1.4 or less, and particularly preferably 1.3 or less. The average aspect ratio may also be 1.0 or more.

[0408] The average aspect ratio is determined by observing the fluororesin composition with a scanning electron microscope (SEM), processing the images of 100 or more randomly selected primary particles, and averaging the ratio of their major axis to their minor axis.

[0409] In another embodiment of the fluororesin composition (5), the proportion of the fluororesin B5 particles having an aspect ratio of 2.5 or more relative to the total number of fluororesin B5 particles is preferably 0.5% or more, more preferably 1.0% or more, even more preferably 1.5% or more, and particularly preferably 2.0% or more. This proportion is also preferably 20% or less, more preferably 15% or less, and even more preferably 10% or less.

[0410] The above ratio is determined by observing the fluororesin composition with a scanning electron microscope (SEM), randomly sampling 100 or more primary particles, processing the images of the particles, calculating the aspect ratio of each particle, and expressing the ratio as a percentage of the total number of the particles sampled.

[0411] The mass ratio (A / B5) ​​of the fluororesin A to the fluororesin B5 is preferably 1 / 99 to 90 / 10, in order to further reduce coloration and further improve tensile properties. The mass ratio A / B5 is more preferably 3 / 97 or more, even more preferably 5 / 95 or more, even more preferably 10 / 90 or more, and particularly preferably 15 / 85 or more. The mass ratio A / B5 is also more preferably 85 / 15 or less, even more preferably 80 / 20 or less, even more preferably 75 / 25 or less, and particularly preferably 70 / 30 or less.

[0412] The total amount of fluororesins A and B5 in the fluororesin composition (5) is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 98% by mass or more, based on the fluororesin composition.

[0413] The fluororesin composition (5) contains fine particles having a primary particle diameter of 1 μm or less. The fine particles are particles of a fluororesin that constitutes the fluororesin composition, and may be particles of at least one type selected from the group consisting of fluororesins A and B5, and are preferably particles of fluororesin B5. The fine particles may be primary particles, and are preferably primary particles of fluororesin B5.

[0414] The primary particle diameter of the fine particles is preferably 500 nm or less, more preferably 450 nm or less, even more preferably 400 nm or less, even more preferably 350 nm or less, and particularly preferably 300 nm or less. The primary particle diameter is also preferably 10 nm or more, more preferably 25 nm or more, even more preferably 50 nm or more, even more preferably 100 nm or more, and particularly preferably 150 nm or more. The primary particle diameter is the average value of the diameters of 100 or more fine particles randomly sampled when the fluororesin composition is observed under a scanning electron microscope (SEM).

[0415] In one embodiment of the fluororesin composition (5), the microparticles preferably have an average aspect ratio of 2.0 or less, more preferably 1.7 or less, even more preferably 1.6 or less, even more preferably 1.5 or less, particularly preferably 1.4 or less, and particularly preferably 1.3 or less. The aspect ratio may also be 1.0 or more.

[0416] The average aspect ratio is determined by observing the fluororesin composition with a scanning electron microscope (SEM), processing images of 100 or more randomly selected fine particles, and averaging the ratio of their major axis to their minor axis.

[0417] In another embodiment of the fluororesin composition (5), the proportion of the microparticles having an aspect ratio of 2.5 or more relative to the total number of the microparticles is preferably 0.5% or more, more preferably 1.0% or more, even more preferably 1.5% or more, and particularly preferably 2.0% or more. The proportion is also preferably 20% or less, more preferably 15% or less, and even more preferably 10% or less.

[0418] The above ratio is determined by observing the fluororesin composition with a scanning electron microscope (SEM), randomly selecting 100 or more of the above microparticles, performing image processing on the microparticles, calculating the aspect ratio of each particle, and calculating the ratio to the total number of the microparticles selected.

[0419] The fluororesin composition (5) preferably contains coarse powder having a particle size of 5 μm or more. The coarse powder is particles of the fluororesin that constitutes the fluororesin composition, and may be particles of at least one type selected from the group consisting of fluororesins A and B5, and is preferably particles of fluororesin A. The coarse powder may be secondary particles, or may be secondary particles of the fluororesin A.

[0420] The particle size of the coarse powder is more preferably 10 μm or more, and is preferably 600 μm or less, more preferably 500 μm or less, and even more preferably 400 μm or less. The particle size of the coarse powder was measured using a Beckman Coulter laser diffraction particle size analyzer (LS13 320) under a dry vacuum pressure of 20 mH2O, and the particle size was determined based on the volume distribution.

[0421] In the fluororesin composition (5), it is preferable that the fine particles are attached to the surfaces of the coarse powder and that the exposed surface of the coarse powder is 60% or less, which further reduces coloration and further improves tensile properties such as tensile breaking strength and tensile breaking strain. The exposed surface is more preferably 55% or less, and even more preferably 50% or less. The proportion of the exposed surface is calculated by dividing the surface area of ​​the coarse powder that is not covered by the fine particles by the surface area of ​​the coarse powder from a 5000x magnification image of the fluororesin composition observed with a scanning electron microscope (SEM).

[0422] The fluororesin composition (5) preferably has an average secondary particle diameter of 5 to 500 μm, more preferably 10 μm or more, even more preferably 25 μm or more, and more preferably 450 μm or less, even more preferably 400 μm or less. The above average secondary particle diameter is measured using a Beckman Coulter laser diffraction particle size distribution analyzer (LS13 320) in a dry state at a vacuum pressure of 20 mH2O, and is equal to the particle diameter corresponding to 50% of the integrated particle size distribution (volume basis).

[0423] The fluororesin composition (5) preferably has a D90 of 50 μm or more, more preferably 70 μm or more, and even more preferably 100 μm or more, and preferably has a D90 of 800 μm or less, more preferably 700 μm or less, and even more preferably 650 μm or less. The above D90 is measured using a Beckman Coulter laser diffraction particle size analyzer (LS13 320) in a dry state at a vacuum pressure of 20 mH2O, and is equal to the particle diameter corresponding to 90% of the integrated particle size distribution (volume basis).

[0424] In order to further reduce coloration and further improve tensile properties, the content of the nonionic surfactant in the fluororesin composition (5) is preferably 1.0 mass% or less, more preferably 0.9 mass% or less, even more preferably 0.8 mass% or less, even more preferably 0.7 mass% or less, and particularly preferably 0.6 mass% or less, relative to the fluororesin composition. The lower limit is not particularly limited, but may be less than the detection limit, or may be 1000 ppm by mass. The content of the nonionic surfactant is measured by ultrasonically extracting 1 g of the freeze-pulverized fluororesin composition in 10 mL of methanol at 60°C, in accordance with "Appendix 28 of the method prescribed by the Minister of Health, Labour and Welfare based on the Ministerial Ordinance on Water Quality Standards, Ministry of Health, Labour and Welfare Notification No. 261 of 2003."

[0425] The fluororesin composition (5) preferably does not contain a nonionic surfactant, and also preferably does not contain a hydrocarbon surfactant.

[0426] Examples of the nonionic surfactant and hydrocarbon surfactant include the compounds exemplified for the fluororesin composition (1).

[0427] In order to further reduce coloration and further improve tensile properties, the fluororesin composition (5) is subjected to ultrasonic extraction of 1 g of the freeze-pulverized fluororesin composition in 10 mL of methanol at 60°C, and the absorbance is measured in accordance with "Appendix 28 of the method prescribed by the Minister of Health, Labour and Welfare based on the Ministerial Ordinance on Water Quality Standards, Ministry of Health, Labour and Welfare Notification No. 261 of 2003," and the content of the components obtained is preferably 1.0 mass% or less, more preferably 0.9 mass% or less, even more preferably 0.8 mass% or less, even more preferably 0.7 mass% or less, and particularly preferably 0.6 mass% or less, relative to the fluororesin composition. The lower limit is not particularly limited, and may be below the detection limit, or may be 1000 ppm by mass. The amount of the above component being within the above range indicates that the fluororesin composition does not contain a nonionic surfactant, or if it does contain one, the content is extremely small.

[0428] In the fluororesin composition (5), in order to further reduce coloration and further improve tensile properties, the content (total amount) of low-molecular-weight fluorine-containing compounds is preferably 1 ppm by mass or less, more preferably 500 ppb by mass or less, even more preferably 100 ppb by mass or less, still more preferably 50 ppb by mass or less, especially preferably 25 ppb by mass or less, particularly preferably 10 ppb by mass or less, especially more preferably 5 ppb by mass or less, especially especially preferably 1 ppb by mass or less, and most preferably less than 1 ppb by mass, relative to the fluororesin composition. The content of the low-molecular-weight fluorine-containing compound is measured by using an extract obtained by Soxhlet extraction of a sample with methanol and a liquid chromatograph mass meter (LC / MS / MS).

[0429] Examples of the low molecular weight fluorine-containing compound include the compounds exemplified for the fluororesin composition (1).

[0430] The form of the fluororesin composition (5) is not particularly limited, but it is preferably in the form of a powder.

[0431] The fluororesin composition (5) can be produced, for example, by a method for producing a fluororesin composition (hereinafter also referred to as a first production method) including a step of obtaining a mixture by mixing powder of the fluororesin A with an aqueous dispersion containing particles of the fluororesin B5 and having a solid content concentration of 70 mass % or less (hereinafter also referred to as a mixing step), a step of drying the mixture (hereinafter also referred to as a drying step), and a step of mixing a filler. In the first production method, an aqueous dispersion with a solid content of 70 mass % or less is used, which allows the powder of fluororesin A and particles of fluororesin B5 to be mixed uniformly. As a result, a fluororesin composition can be produced that is less colored and has excellent tensile properties (e.g., tensile strength at break, tensile strain at break) despite containing a fluororesin that has a history of being heated to a temperature above its melting point.

[0432] The content of the fluororesin B5 particles is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 98% by mass or more, based on the solid content of the aqueous dispersion.

[0433] The aqueous dispersion in the first production method usually contains an aqueous medium, and may be an aqueous dispersion in which particles of the fluororesin B5 are dispersed. An aqueous medium refers to a liquid containing water. The aqueous medium is not particularly limited as long as it contains water, and may contain water and, for example, a fluorine-free organic solvent such as an alcohol, ether, or ketone, and / or a fluorine-containing organic solvent having a boiling point of 40° C. or lower. The aqueous medium preferably contains 90% by mass or more, and more preferably 95% by mass or more, of water.

[0434] The aqueous dispersion has a solids concentration of 70% by mass or less. In order to produce a fluororesin composition with less coloration and more excellent tensile properties, the solids concentration is preferably 50% by mass or less, more preferably 45% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less. The solids concentration is also preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more. The solid content concentration is calculated from the formula: P = [Z / X] × 100 (% by mass) by placing approximately 1 g (X g) of the aqueous dispersion in an aluminum cup with a diameter of 5 cm, heating it at 110°C for 30 minutes to obtain the heating residue (Y g), and further heating the obtained heating residue (Y g) at 300°C for 30 minutes to obtain the heating residue (Z g).

[0435] The aqueous dispersion may contain a hydrocarbon surfactant, which preferably does not contain a fluorine atom.

[0436] Examples of the hydrocarbon surfactant include those mentioned above.

[0437] The content of the hydrocarbon surfactant is preferably 12% by mass or less, more preferably 8% by mass or less, even more preferably 6% by mass or less, even more preferably 4% by mass or less, particularly preferably 2% by mass or less, and particularly preferably 1% by mass or less, based on the solid content of the aqueous dispersion, from the viewpoint of producing a fluororesin composition with less coloration and more excellent tensile properties. The content of the hydrocarbon surfactant may also be 1 ppm by mass or more, 10 ppm by mass or more, 100 ppm by mass or more, or 500 ppm by mass or more.

[0438] The content of the nonionic surfactant is preferably 12% by mass or less, more preferably 8% by mass or less, even more preferably 6% by mass or less, even more preferably 4% by mass or less, particularly preferably 2% by mass or less, and particularly preferably 1% by mass or less, based on the solid content of the aqueous dispersion, from the viewpoint of producing a fluororesin composition with less coloration and more excellent tensile properties. The content of the nonionic surfactant may also be 1 ppm by mass or more, 10 ppm by mass or more, 100 ppm by mass or more, or 500 ppm by mass or more.

[0439] The aqueous dispersion preferably does not contain a nonionic surfactant, and also preferably does not contain a hydrocarbon surfactant.

[0440] In order to produce a fluororesin composition with less coloration and more excellent tensile properties, the aqueous dispersion preferably has a low-molecular-weight fluorine-containing compound content (total amount) of 1 ppm by mass or less, more preferably 500 ppb by mass or less, even more preferably 100 ppb by mass or less, even more preferably 50 ppb by mass or less, especially preferably 25 ppb by mass or less, particularly preferably 10 ppb by mass or less, especially more preferably 5 ppb by mass or less, especially especially preferably 1 ppb by mass or less, and most preferably less than 1 ppb by mass. The content of the low-molecular-weight fluorine-containing compound is measured by subjecting a sample to Soxhlet extraction with methanol and then using a liquid chromatograph mass meter (LC / MS / MS).

[0441] Examples of the low-molecular-weight fluorine-containing compound include those mentioned above.

[0442] The aqueous dispersion can be produced, for example, by emulsion polymerization of the monomers necessary for constituting the fluororesin B5 in an aqueous medium in the presence of an anionic surfactant and a polymerization initiator. In the emulsion polymerization, a chain transfer agent, a buffer, a pH adjuster, a stabilizing aid, a dispersion stabilizer, etc. may be used as necessary. Those skilled in the art can control the composition and physical properties of the fluororesin B5, the physical properties of the particles, and the like, by adjusting the conditions of the emulsion polymerization.

[0443] A hydrocarbon surfactant may be added to the aqueous dispersion obtained by the emulsion polymerization. Examples of the hydrocarbon surfactant include those mentioned above.

[0444] The aqueous dispersion obtained by the emulsion polymerization or the aqueous dispersion obtained by adding the hydrocarbon surfactant may be contacted with an anion exchange resin or a mixed bed containing an anion exchange resin and a cation exchange resin, concentrated, or treated with both of these. By carrying out the above treatment, low-molecular-weight fluorine-containing compounds can be removed.

[0445] The anion exchange resin and the mixed bed are not particularly limited, and known ones can be used. Furthermore, known methods can be used for contacting the anion exchange resin or the mixed bed.

[0446] As the concentration method, known methods can be used, such as phase separation, centrifugal sedimentation, cloud point concentration, electroconcentration, electrophoresis, filtration using ultrafiltration, filtration using a reverse osmosis membrane (RO membrane), and nanofiltration.

[0447] The aqueous dispersion obtained by the emulsion polymerization (before the addition of the hydrocarbon surfactant) may be subjected to the mixing step, or the aqueous dispersion obtained by adding the hydrocarbon surfactant may be subjected to the mixing step, or the aqueous dispersion obtained by contacting with the ion exchange resin or by concentrating may be subjected to the mixing step. If the solid content concentration exceeds 50 mass %, it may be diluted before use.

[0448] The aqueous dispersion preferably has a viscosity at 25°C of 100 mPa s or less, more preferably 50 mPa s or less, even more preferably 40 mPa s or less, and particularly preferably 30 mPa s or less, in order to produce a fluororesin composition with less coloration and more excellent tensile properties. The viscosity may also be 0.1 mPa s or more. The viscosity is measured at 25° C. using a B-type rotational viscometer (manufactured by Toki Sangyo Co., Ltd., rotor No. 2) at a rotation speed of 60 rpm for a measurement time of 120 seconds.

[0449] The powder of fluororesin A and the aqueous dispersion are preferably mixed so that the mass ratio (A / B5) ​​of the powder of fluororesin A to the particles of fluororesin B5 is 1 / 99 to 90 / 10, in order to produce a fluororesin composition with less coloration and more excellent tensile properties. The mass ratio A / B5 is more preferably 3 / 97 or more, even more preferably 5 / 95 or more, even more preferably 10 / 90 or more, and particularly preferably 15 / 85 or more. The mass ratio A / B5 is also more preferably 85 / 15 or less, even more preferably 80 / 20 or less, even more preferably 75 / 25 or less, and particularly preferably 70 / 30 or less.

[0450] If the solid content or viscosity of the mixture obtained in the mixing step is too high, the mixture may be diluted to adjust the solid content or viscosity to within the above range.

[0451] The first production method may include a coagulation step of coagulating the mixture obtained in the mixing step. Examples of coagulation methods include freezing or mechanical shearing to aggregate the emulsified particles. Stirring may be performed while adding a coagulant, such as a water-soluble organic compound (e.g., methanol or acetone), an inorganic salt (e.g., potassium nitrate or ammonium carbonate), or an inorganic acid (e.g., hydrochloric acid, sulfuric acid, or nitric acid). The coagulation may also be performed continuously using an in-line mixer or the like.

[0452] In the drying step, the mixture obtained in the mixing step is dried to obtain a fluororesin composition. When the first production method includes the coagulation step, the wet powder obtained by coagulation is dried. The drying method is not particularly limited, and any known method can be used, for example, vacuum, high frequency, hot air, or the like. The drying temperature is preferably 50°C or higher, more preferably 70°C or higher, even more preferably 100°C or higher, particularly preferably 150°C or higher, and is preferably 300°C or lower, more preferably 250°C or lower.

[0453] The first production method may include a pulverization step of pulverizing the fluororesin composition obtained in the drying step. The pulverization may be carried out by a known method, for example, using a pulverizer such as an air jet mill, a hammer mill, a force mill, a stone mill, or a freeze pulverizer.

[0454] In the step of mixing the filler, the filler may be mixed with the powder of the fluororesin A1, may be mixed with the aqueous dispersion, may be mixed with the mixture obtained in the step of mixing the powder of the fluororesin A1 and the aqueous dispersion, may be mixed with the wet powder obtained in the coagulation step, or may be mixed with the dry powder obtained in the drying step.

[0455] The fluororesin composition (5) can also be produced by a production method for a fluororesin composition (hereinafter also referred to as a second production method), which includes a step of mixing powder of the fluororesin A with an aqueous dispersion containing particles of the fluororesin B5 and no hydrocarbon surfactant to obtain a mixture (mixing step), a step of drying the mixture (drying step), and a step of mixing a filler. In the second production method, an aqueous dispersion containing no hydrocarbon surfactant is used, which reduces coloration and the effect on physical properties caused by residual hydrocarbon surfactant. As a result, a fluororesin composition with little coloration and excellent tensile properties can be produced, even though it contains a fluororesin that has a history of being heated to a temperature above its melting point.

[0456] The powder of fluororesin A and the particles of fluororesin B5 are as described above in the first production method.

[0457] The aqueous dispersion in the second production method does not contain a hydrocarbon surfactant, and examples of the hydrocarbon surfactant include those exemplified for the first production method. Other components and physical properties of the aqueous dispersion than those mentioned above can be the same as those in the first production method.

[0458] A preferred embodiment of the mixing step in the second production method is the same as that described above for the first production method.

[0459] As the drying step in the second manufacturing method, a step similar to the drying step in the first manufacturing method can be adopted.

[0460] Other optional steps and preferred aspects that can be employed in the second production method are the same as those in the first production method.

[0461] The first and second production methods preferably further include a step of granulating the obtained fluororesin composition, thereby obtaining a fluororesin composition with a high apparent density and excellent handleability. The granulation method may be any known method, such as underwater granulation, hot water granulation, emulsion dispersion granulation, emulsion hot water granulation, solventless granulation, or dry solvent granulation.

[0462] As the first fluororesin composition of the present disclosure, among others, fluororesin composition (1), fluororesin composition (2a), fluororesin composition (2b), fluororesin composition (3a), fluororesin composition (3b), and fluororesin composition (4) are preferred.

[0463] The first fluororesin composition of the present disclosure preferably has a tensile strength at break of 8 MPa or more, more preferably 9 MPa or more, even more preferably 10 MPa or more, and particularly preferably 13 MPa or more. The upper limit is not particularly limited, but may be, for example, 20 MPa. The tensile breaking strength is measured in accordance with ASTM D1708 using a dumbbell punched from a molded article sintered in the following steps: placing 35 g of the fluororesin composition in a φ100 mm mold, compression-molding under a pressure of 30 MPa for 1 minute, heating from room temperature to 300°C over 3 hours, then heating from 300°C to 370°C over 4 hours, holding at 370°C for 12 hours, cooling to 300°C over 5 hours, and cooling to room temperature over 1 hour. The tensile breaking strength can also be measured using a ram-extrusion molded product by the following method. A molded body is obtained by extruding using a vertical ram extruder with a cylinder diameter of 27 mm and a total length of 1,300 mm, set at a preheating zone of 270°C and a molding zone of 370°C, with a filling length of 70 mm, a pressure of 10 MPa, a pressurizing time of 20 seconds, and one cycle of 40 seconds. This molded body is then cut to a thickness of 2.0 mm, a width of 20 mm, and a length of 150 mm to prepare a flat plate, which is then punched out to prepare a dumbbell, and measurement is performed in accordance with ASTM D 1708.

[0464] The first fluororesin composition of the present disclosure may have a tensile break strain of 75% or more, preferably 150% or more, more preferably 200% or more, even more preferably 250% or more, even more preferably 300% or more, especially preferably 360% or more, and particularly preferably 400% or more. The upper limit is not particularly limited, but may be, for example, 600%. The tensile breaking strain is measured in accordance with ASTM D1708 using a dumbbell punched out of a molded article sintered in the following steps: placing 35 g of the fluororesin composition in a φ100 mm mold, compression-molding under a pressure of 30 MPa for 1 minute, heating from room temperature to 300°C over 3 hours, then heating from 300°C to 370°C over 4 hours, holding at 370°C for 12 hours, cooling to 300°C over 5 hours, and then cooling to room temperature over 1 hour. The tensile breaking strain can also be measured using a ram-extrusion molded product by the following method. A molded body is obtained by extruding using a vertical ram extruder with a cylinder diameter of 27 mm and a total length of 1,300 mm, set at a preheating zone of 270°C and a molding zone of 370°C, with a filling length of 70 mm, a pressure of 10 MPa, a pressurizing time of 20 seconds, and one cycle of 40 seconds. This molded body is then cut to a thickness of 2.0 mm, a width of 20 mm, and a length of 150 mm to prepare a flat plate, which is then punched out to prepare a dumbbell, and measurement is performed in accordance with ASTM D 1708.

[0465] The first fluororesin composition of the present disclosure can be suitably used as a molding material. The method for molding the fluororesin composition is not particularly limited, but includes compression molding, ram extrusion molding, isostatic molding, etc. Among them, compression molding and ram extrusion molding are preferred. The first fluororesin composition of the present disclosure is preferably a powder for compression molding or a powder for ram extrusion molding.

[0466] The present disclosure also provides a molded article (hereinafter also referred to as the first molded article of the present disclosure) obtained by compression molding and baking the first fluororesin composition of the present disclosure, or by ram extrusion molding. The first molded article of the present disclosure has excellent tensile properties despite containing a fluororesin that has a history of being heated to a temperature equal to or higher than its melting point.

[0467] The compression molding can be carried out, for example, by maintaining a pressure of 10 to 50 MPa for 1 minute to 30 hours.

[0468] The calcination can be carried out, for example, by heating at a temperature of 350 to 380° C. for 0.5 to 50 hours.

[0469] The ram extrusion molding can be carried out, for example, using a vertical ram extruder with a cylinder diameter of 5 to 50 mm, set at a preheating zone of 230 to 330°C and a molding zone of 320 to 400°C, with a filling length of 70 mm, a pressure of 1 to 50 MPa, a pressurizing time of 5 to 90 seconds, and one cycle of 10 to 120 seconds.

[0470] The present disclosure also provides a fluororesin composition having one or more endothermic peaks in the range of 320 to 335°C, which, when thermally decomposed at 600°C in a nitrogen atmosphere, produces a residue of 15% by mass or less relative to the fluororesin composition, and which exhibits electrical conductivity or thermal conductivity of 0.3 W / m K or more (hereinafter also referred to as a second fluororesin composition of the present disclosure). The second fluororesin composition of the present disclosure has the above-described configuration and is therefore excellent in tensile properties (for example, tensile strength at break, tensile strain at break) and handleability (handleability as a powder). The second fluororesin composition of the present disclosure also has electrical or thermal conductivity.

[0471] The second fluororesin composition of the present disclosure has one or more endothermic peaks (melting points) in the range of 320 to 335°C. The endothermic peak is preferably 323°C or higher, more preferably 325°C or higher, and is preferably 333°C or lower, more preferably 330°C or lower. The endothermic peak (melting point) being within the above range indicates that the resin contains a fluororesin that has a history of being heated to a temperature equal to or higher than the melting point and does not exhibit melt fluidity.

[0472] In this specification, the endothermic peak (melting point) of a fluororesin composition is the temperature corresponding to the minimum point in the heat of fusion curve obtained by differential scanning calorimetry (DSC) at a heating rate of 10°C / min using an X-DSC7000 (manufactured by Hitachi High-Tech Science Corporation). When one melting peak has two or more minimum points, each of them is considered to be an endothermic peak (melting point).

[0473] As the fluororesin that has a history of being heated to a temperature equal to or higher than its melting point and does not exhibit melt fluidity, the above-mentioned fluororesin A can be used. PTFE is preferred as the fluororesin A. The PTFE may be a high molecular weight PTFE.

[0474] The PTFE as the fluororesin A may be a homopolymer of TFE, or may be a modified PTFE containing 99.0% by mass or more of polymerization units based on TFE and 1.0% by mass or less of polymerization units based on a modifying monomer (hereinafter also referred to as "modified monomer units"). The modified PTFE may consist only of polymerization units based on TFE and modifying monomer units. The modifying monomer may be the monomer described above for the modified PTFE as the fluororesin A in the first fluororesin composition of the present disclosure. The suitable range of the content of the modifying monomer unit is also the same as the range described for the first fluororesin composition of the present disclosure. The suitable ranges of the standard specific gravity (SSG) and melting point of the PTFE as the fluororesin A in the second fluororesin composition of the present disclosure are the same as those described for the first fluororesin composition of the present disclosure.

[0475] The second fluororesin composition of the present disclosure may contain particles of fluororesin A. The particles of fluororesin A may be secondary particles of fluororesin A. The preferred ranges of the average secondary particle size and D90 of the fluororesin A particles in the second fluororesin composition of the present disclosure are the same as those described for the first fluororesin composition of the present disclosure. The fluororesin A particles in the second fluororesin composition of the present disclosure can be obtained by the method described for the first fluororesin composition of the present disclosure.

[0476] The second fluororesin composition of the present disclosure generates residues in an amount of 15% by mass or less based on the fluororesin composition when thermally decomposed at 600°C under a nitrogen atmosphere. The second fluororesin composition of the present disclosure preferably has a residue generated by thermal decomposition at 600°C under a nitrogen atmosphere of 10% by mass or less, more preferably 8% by mass or less, and may have a residue of 1% by mass or more, based on the fluororesin composition. The residue can be determined from the weight loss in the TG curve obtained by simultaneous thermogravimetry and differential thermal analysis (TG / DTA) at 600°C in a nitrogen atmosphere at a temperature increase rate of 10°C / min.

[0477] The second fluororesin composition of the present disclosure exhibits electrical conductivity or thermal conductivity of 0.3 W / m·K or more. In this specification, the term "conductive" means that the volume resistivity is 10 5 This means that the resistance is Ω·cm or less. The second fluororesin composition of the present disclosure has a volume resistivity of 10 4 It is preferable that the resistance is 10 Ω·cm or less, and the conductivity is further improved. 3 It is more preferable that the resistance is 10 Ω·cm or less. 2 It is particularly preferable that the resistance is Ω·cm or less, and even more preferably 10 Ω·cm or less. -2 It may be Ω·cm. The volume resistivity is measured in accordance with ASTM D 991.

[0478] The second fluororesin composition of the present disclosure preferably contains a conductive filler, which can impart good electrical conductivity to the fluororesin composition. Examples of the conductive filler include the conductive fillers described above for the first fluororesin composition of the present disclosure. As the conductive filler, a carbon filler is preferred, and carbon black is more preferred. The second fluororesin composition of the present disclosure can be imparted with good conductivity even when using carbon black, which is relatively inexpensive and easy to handle. The carbon black is preferably conductive carbon black, more preferably at least one selected from the group consisting of acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black, and even more preferably at least one selected from the group consisting of acetylene black, ketjen black, and furnace black. The preferred range of the oil absorption of the carbon black is the same as the range described for the first fluororesin composition of the present disclosure. The preferred range of the conductive filler content is the same as the range explained for the first fluororesin composition of the present disclosure.

[0479] The second fluororesin composition of the present disclosure preferably has a thermal conductivity of 0.4 W / m K or more, more preferably 0.5 W / m K or more, even more preferably 0.6 W / m K or more, and even more preferably 0.7 W / m K or more. The thermal conductivity is measured in accordance with JIS H7903 in an atmosphere of room temperature 23°C, with a heater temperature of 42°C, a chiller temperature of 12°C, and a measuring load of 400 N, using a vertical ram extruder with a cylinder diameter of 27 mm and a total length of 1300 mm, set at a preheating zone of 270°C and a molding zone of 370°C, with a filling length of 70 mm, a pressure of 10 MPa, a pressurization time of 20 seconds, and one cycle of 40 seconds, to obtain a molded body, which is then cut to a thickness of 2.0 mm, a width of 20 mm, and a length of 20 mm to prepare a flat plate.

[0480] The second fluororesin composition of the present disclosure preferably contains a thermally conductive filler, which can impart good thermal conductivity to the fluororesin composition. The thermally conductive filler may be any of the thermally conductive fillers described above for the first fluororesin composition of the present disclosure. The thermally conductive filler is preferably boron nitride. The second fluororesin composition of the present disclosure can be provided with good thermal conductivity. The preferred range of the content of the thermally conductive filler is the same as the range explained for the first fluororesin composition of the present disclosure.

[0481] The second fluororesin composition of the present disclosure may further comprise at least one fluororesin B selected from the group consisting of fluororesins exhibiting melt flowability and fluororesins not exhibiting melt flowability and having no history of being heated to a temperature equal to or higher than their melting point. The inclusion of the fluororesin B improves tensile properties. As the fluororesin B, the fluororesin B described above for the first fluororesin composition of the present disclosure can be used. The suitable ranges for the contents of fluororesins A and B in the second fluororesin composition of the present disclosure are the same as those described for the first fluororesin composition of the present disclosure.

[0482] The second fluororesin composition of the present disclosure preferably further has one or more endothermic peaks (melting points) in the range above 335°C, and preferably has one or more endothermic peaks (melting points) at or below 355°C, and more preferably has one or more endothermic peaks (melting points) at or below 350°C. Having a melting point in the above temperature range means that the fluororesin composition further contains a fluororesin having an endothermic peak (melting point) in the range above 335°C, i.e., a fluororesin that does not exhibit melt fluidity and has no history of being heated to a temperature equal to or higher than its melting point and / or a fluororesin that does not exhibit melt fluidity and has a portion that does not have a history of being heated to a temperature equal to or higher than its melting point.

[0483] The fluororesin that does not exhibit melt flowability and has no history of being heated to a temperature equal to or higher than its melting point, such as fluororesins B2 to B4, can be used as the fluororesin B described above in the first fluororesin composition of the present disclosure. The preferred range of the content of the fluororesin that does not exhibit melt flowability and has no history of being heated to a temperature equal to or higher than its melting point is the same as the range described for the content of fluororesin B (or fluororesins B2 to B4) in the first fluororesin composition of the present disclosure.

[0484] The fluororesin that does not exhibit melt flowability and has a portion that has no history of being heated to a temperature equal to or higher than its melting point can be the fluororesin C described above in connection with the first fluororesin composition of the present disclosure. The preferred range of the content of the fluororesin that does not exhibit melt flowability and has a portion that has no history of being heated to a temperature equal to or higher than its melting point is the same as the range described for the fluororesin C in the first fluororesin composition of the present disclosure.

[0485] The content of the fluororesin having an endothermic peak (melting point) above 335°C in the second fluororesin composition of the present disclosure is preferably 0 to 90% by mass relative to the fluororesin composition, in order to further improve tensile properties. The content is more preferably 1% by mass or more, even more preferably 10% by mass or more, even more preferably 15% by mass or more, especially preferably 20% by mass or more, particularly preferably more than 20% by mass, especially more preferably 25% by mass or more, especially more preferably 30% by mass or more, especially especially preferably 40% by mass or more, and more preferably 80% by mass or less, even more preferably 75% by mass or less, even more preferably 70% by mass or less, especially preferably 65% ​​by mass or less, especially preferably 60% by mass or less, especially more preferably 50% by mass or less.

[0486] The second fluororesin composition of the present disclosure does not exhibit melt flowability. The preferred range of the MFR of the second fluororesin composition of the present disclosure is the same as the range described for the first fluororesin composition of the present disclosure.

[0487] Furthermore, when a preform (unfired molded body) obtained by compression molding the second fluororesin composition of the present disclosure is heated at a temperature equal to or higher than the melting point of the fluororesin composition for 1 hour or longer, it is preferable that the reduction in thickness after heating relative to the thickness before heating is less than 20% or that the thickness after heating increases compared to the thickness before heating, since these also mean that the fluororesin composition does not exhibit melt flowability.

[0488] The second fluororesin composition of the present disclosure preferably contains TFE units and modified monomer units based on a modified monomer copolymerizable with TFE. The fluororesin composition may contain only TFE units and modified monomer units as polymerization units. The preferred range of the content of the modified monomer is the same as that described for the first fluororesin composition of the present disclosure.

[0489] The second fluororesin composition of the present disclosure preferably contains 99.0 mass % or more of TFE units based on all polymerized units.

[0490] The content of the polymerized units constituting the second fluororesin composition of the present disclosure can be calculated by an appropriate combination of NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer. In addition, when the raw material composition is known, the content can also be determined by calculation from the raw material composition.

[0491] In order to achieve even better handleability, the second fluororesin composition of the present disclosure preferably has an apparent density of 0.40 g / ml or more, more preferably 0.42 g / ml or more, even more preferably 0.45 g / ml or more, and particularly preferably 0.47 g / ml or more. There is no particular upper limit, but it may be 1.00 g / ml. The apparent density is measured in accordance with JIS K 6891.

[0492] The second fluororesin composition of the present disclosure preferably has an angle of repose of less than 40°, more preferably less than 38°, and even more preferably less than 35°, in view of excellent fluidity and even better handleability. The above angle of repose is a value obtained by placing a funnel with a total height of 115 mm, a foot diameter of φ26 mm, a foot length of 35 mm, and an intake opening of 60° so that the height from the bottom of the funnel to the sample drop surface is 100 mm, dropping 40 g of sample from the funnel, and measuring the angle of the lower half of the peak of the dropped sample with a protractor.

[0493] The second fluororesin composition of the present disclosure preferably has an average secondary particle size of 5 to 700 μm. The suitable range of the average secondary particle size in the second fluororesin composition of the present disclosure is the same as the range described for the first fluororesin composition of the present disclosure.

[0494] The form of the second fluororesin composition of the present disclosure is not particularly limited, but is preferably a powder.

[0495] The second fluororesin composition of the present disclosure preferably has a tensile strength at break of 8 MPa or more, more preferably 9 MPa or more, even more preferably 10 MPa or more, and particularly preferably 13 MPa or more. The upper limit is not particularly limited, but may be, for example, 20 MPa. The tensile strength at break is measured in accordance with ASTM D1708 using a dumbbell prepared in the same manner as in the first fluororesin composition of the present disclosure.

[0496] The second fluororesin composition of the present disclosure may have a tensile break strain of 75% or more, preferably 150% or more, more preferably 200% or more, even more preferably 250% or more, even more preferably 300% or more, especially preferably 360% or more, and particularly preferably 400% or more. The upper limit is not particularly limited, but may be, for example, 600%. The tensile breaking strain is measured in accordance with ASTM D1708 using a dumbbell prepared in the same manner as in the first fluororesin composition of the present disclosure.

[0497] The second fluororesin composition of the present disclosure can be suitably used as a molding material. The method for molding the fluororesin composition is not particularly limited, but includes compression molding, ram extrusion molding, isostatic molding, etc. Among them, compression molding and ram extrusion molding are preferred, and ram extrusion molding is more preferred. The second fluororesin composition of the present disclosure is preferably a powder for compression molding or a powder for ram extrusion molding, and more preferably a powder for ram extrusion molding.

[0498] The second fluororesin composition of the present disclosure is preferably not for use in porous media. In this specification, the term "porous" means that when a cross section of a molded body is observed, the area occupied by voids of 10 μm or more is 20% or more per unit area.

[0499] The present disclosure also provides a molded article obtained by ram extrusion molding the second fluororesin composition of the present disclosure (hereinafter also referred to as the second molded article of the present disclosure). The second molded article of the present disclosure has excellent tensile properties despite containing a fluororesin that has a history of being heated to a temperature equal to or higher than the melting point.

[0500] The ram extrusion molding can be performed using the methods described above.

[0501] The first and second molded articles of the present disclosure preferably have a tensile strength at break of 8 MPa or more, more preferably 9 MPa or more, even more preferably 10 MPa or more, and particularly preferably 13 MPa or more. The upper limit is not particularly limited, but may be, for example, 20 MPa. The tensile breaking strength is measured in accordance with ASTM D1708.

[0502] The first and second molded articles of the present disclosure may have a tensile breaking strain of 75% or more, preferably 150% or more, more preferably 200% or more, even more preferably 250% or more, even more preferably 300% or more, especially preferably 360% or more, and particularly preferably 400% or more. The upper limit is not particularly limited, but may be, for example, 600%. The tensile breaking strain is measured in accordance with ASTM D1708.

[0503] The first and second molded articles of the present disclosure have a volume resistivity of 10 4 It is preferable that the resistance is 10 Ω·cm or less, and the conductivity is further improved. 3 It is more preferable that the resistance is 10 Ω·cm or less. 2 It is particularly preferable that the resistance is Ω·cm or less, and even more preferably 10 Ω·cm or less. -2 It may be Ω·cm. The volume resistivity is measured in accordance with ASTM D 991.

[0504] The first and second molded articles of the present disclosure have a volume resistivity of 10 or more when used for the purpose of antistatic purposes. 5 ~10 8 It is preferably Ω·cm.

[0505] For the purpose of improving thermal conductivity, the first and second molded articles of the present disclosure preferably have a thermal conductivity of 0.3 W / m K or more, and for further improving thermal conductivity, a thermal conductivity of 0.5 W / m K or more is preferred. The volume resistivity is measured in accordance with JIS H7903.

[0506] Molded articles obtained from the first and second fluororesin compositions of the present disclosure are preferably non-porous.

[0507] Molded articles obtained from the first and second fluororesin compositions of the present disclosure can be suitably used for lining sheets, packings, gaskets, diaphragm valves, heat-resistant electric wires, heat-resistant insulating tapes for vehicle motors, generators, etc., release sheets, sealing materials, casings, sleeves, bellows, hoses, piston rings, butterfly valves, square tanks, wafer carriers, circuit boards, etc.

[0508] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims. [Example]

[0509] The present disclosure will now be described in more detail with reference to examples, but the present disclosure is not limited to these examples.

[0510] Various physical properties were measured by the following methods.

[0511] (Melting Point) The melting point was determined as the temperature corresponding to the minimum point in the heat of fusion curve obtained by differential scanning calorimetry (DSC) at a heating rate of 10°C / min using an X-DSC7000 (Hitachi High-Tech Science Corporation). When there were two or more minimum points in one melting peak, each was considered to be the melting point. When the content of fluororesin B was 5% by mass or less, differential scanning calorimetry (DSC) was performed using an X-DSC7000 (manufactured by Hitachi High-Tech Science Corporation) by heating the sample at a heating rate of 10°C / min to 300°C, which is below the melting point of fluororesin B, and then holding the sample at 300°C for 10 minutes. The temperature was then increased at a heating rate of 10°C / min, and the temperature was determined as the temperature corresponding to the minimum point on the heat of fusion curve.

[0512] (residue) The weight loss was determined from the weight loss in the TG curve obtained by simultaneous differential thermal and thermogravimetric analysis (TG / DTA) at 600°C in a nitrogen atmosphere at a heating rate of 10°C / min using a TG / DTA7200 (Hitachi High-Tech Science Corporation).

[0513] (Monomer composition of fluororesin) 19 Measurement was performed by F-NMR.

[0514] (Monomer Composition of Fluorine Resin Composition) It was calculated from the raw material composition.

[0515] (Powder secondary particle size) Measurements were performed dry using a Beckman Coulter laser diffraction particle size analyzer (LS13 320) at a vacuum pressure of 20 mH2O, and the particle size distribution (volume basis) was calculated. The average secondary particle size was defined as the particle size corresponding to 50% of the cumulative particle size distribution. The particle size corresponding to 10% was defined as D10, and the particle size corresponding to 90% was defined as D90.

[0516] (Average primary particle size) An aqueous dispersion with a solids concentration adjusted to 0.5% by mass was dropped onto aluminum foil, and the foil was dried at 150°C for 1 hour to remove the water. The resulting particles were then observed under a scanning electron microscope (SEM) and the average diameter of 100 or more randomly selected particles was calculated.

[0517] (aspect ratio) An aqueous dispersion of fluororesin diluted to a solids concentration of 0.5% by mass was observed using a scanning electron microscope (SEM). Images of 100 or more randomly selected particles were processed, and the average aspect ratio was calculated from the average ratio of their major axis to their minor axis. The proportion of particles with an aspect ratio of 2.5 or more was determined by observing an aqueous fluororesin dispersion diluted to a solids concentration of 0.5% by mass with a scanning electron microscope (SEM), randomly sampling 100 or more particles, processing the images, and calculating the aspect ratio of each particle, which was then expressed as a proportion of the total number of particles sampled.

[0518] (Solid content concentration of aqueous dispersion) The solid content concentration (P mass %) in the aqueous dispersion was calculated from the formula: P = [Z / X] × 100 (mass %) by placing approximately 1 g (X g) of the sample in an aluminum cup with a diameter of 5 cm, heating it at 110°C for 30 minutes to obtain the heating residue (Y g), and then heating the obtained heating residue (Y g) at 300°C for 30 minutes to obtain the heating residue (Z g).

[0519] (Content of nonionic surfactant in aqueous dispersion) The content of the nonionic surfactant in the aqueous dispersion relative to the PTFE (N mass %) was calculated from the formula: N = [(YZ) / Z] × 100 (mass %), using the heating residue (Yg) obtained by placing approximately 1 g (Xg) of the sample in an aluminum cup with a diameter of 5 cm and heating it at 110°C for 30 minutes, and the heating residue (Zg) obtained by further heating the obtained heating residue (Yg) at 300°C for 30 minutes.

[0520] (apparent density) Measurement was carried out in accordance with JIS K 6891.

[0521] (Standard specific gravity (SSG)) Using samples molded in accordance with ASTM D4895 89, measurements were made by the water displacement method in accordance with ASTM D 792.

[0522] (Angle of repose) A funnel with a total height of 115 mm, a foot diameter of φ26 mm, a foot length of 35 mm, and an intake opening of 60° was placed so that the height from the bottom of the funnel to the sample drop surface was 100 mm, and 40 g of sample was dropped from the funnel. The angle of the lower half of the peak of the dropped sample was measured with a protractor and used as the angle of repose.

[0523] (Maximum straight length) More than 100 secondary particles were observed using SEM images, and the longest diameter of each secondary particle was measured. The longest long diameter among them was taken as the maximum linear length.

[0524] (MFR) In accordance with ASTM D1238, a melt indexer was used to measure the mass of polymer (g / 10 min) flowing out of a nozzle with an inner diameter of 2.095 mm and a length of 8 mm at a measurement temperature (e.g., 372°C for PFA and FEP, 297°C for ETFE) determined depending on the type of fluororesin and a load (e.g., 5 kg for PFA, FEP, and ETFE) per 10 min.

[0525] (Tensile test) In Examples 1 to 6, 35 g of powder was placed in a φ100 mm mold and compression molded at 30 MPa for 1 minute. The temperature was then increased from room temperature to 300°C over 3 hours, then increased from 300°C to 370°C over 4 hours, and held at 370°C for 12 hours. The temperature was then decreased to 300°C over 5 hours, and then decreased to room temperature over 1 hour. This resulted in a molded product, which was then punched out to prepare dumbbells. Tensile tests were conducted in accordance with ASTM D 1708 to measure the tensile strength and strain at break. In Examples 7 to 16, when ram-extrusion molded products were used, the following methods were used. The material was extruded using a vertical ram extruder with a cylinder diameter of 27 mm and a total length of 1,300 mm, set at a preheating zone of 270°C and a molding zone of 370°C, with a filling length of 70 mm, a pressure of 10 MPa, a pressurization time of 20 seconds, and one cycle of 40 seconds, to obtain a molded product. This molded product was then cut to a thickness of 2.0 mm, a width of 20 mm, and a length of 150 mm to prepare a flat plate, and this molded product was punched out to prepare a dumbbell. A tensile test was performed in accordance with ASTM D 1708 to measure the tensile breaking strength and tensile breaking strain.

[0526] (Melt fluidity of fluororesin composition) When a fluororesin composition (powder) was compression molded and fired under the same conditions as in the tensile test, if the thickness after firing was reduced by 20% or more compared to the thickness before firing, the fluororesin composition was judged to have melt fluidity. If the reduction rate before and after firing was less than 20% or if the thickness after firing was greater than the thickness before firing, the fluororesin composition was judged to not have melt fluidity.

[0527] (volume resistivity) In Example 7, a molded body was obtained by extruding a vertical ram extruder with a cylinder diameter of 27 mm and a total length of 1300 mm, set to a preheating zone of 270°C and a molding zone of 370°C, at a filling length of 70 mm, a pressure of 10 MPa, a pressurization time of 20 seconds, and a cycle of 40 seconds. This molded body was cut to a thickness of 2.0 mm, a width of 20 mm, and a length of 150 mm to prepare a flat plate. The volume resistivity was measured in accordance with ASTM D 991 using a digital ohmmeter R506 (manufactured by Kawaguchi Electric Works, Ltd.) at a room temperature of 23°C and a humidity of 50% with a voltage electrode distance of 60 mm and a current electrode distance of 100 mm. In Examples 8 to 14, the volume resistivity was measured in accordance with JIS K 7194 using a Loresta GX MCP-T700 (manufactured by Mitsubishi Chemical Analytical Co., Ltd.) at a room temperature of 23°C and a humidity of 50%.

[0528] (thermal conductivity) A molded body was obtained by extruding the molded body into a 2.0 mm thick, 20 mm wide, and 20 mm long plate using a vertical ram extruder with a cylinder diameter of 27 mm and a total length of 1300 mm, set at a preheating zone of 270°C and a molding zone of 370°C, with a filling length of 70 mm, a pressure of 10 MPa, a pressurization time of 20 seconds, and a cycle of 40 seconds. The molded body was cut to prepare a plate. The thermal conductivity was measured using a TCM1001 (manufactured by Rhesca Corporation) in accordance with JIS H7903 under a room temperature of 23°C, a heater temperature of 42°C, a chiller temperature of 12°C, and a measurement load of 400 N.

[0529] (Non-porous) The fluororesin composition (powder) was ram-extruded under the same conditions as the thermal conductivity test above, and the cross section of the resulting molded article was observed using SEM images. If the proportion of voids of 10 μm or more per unit area was 20% or more, it was judged to be porous. If the proportion was less than 20%, it was judged to be "not porous" and indicated by "○" in Table 1, and if the proportion was 20% or more, it was judged to be "porous" and indicated by "×" in Table 1.

[0530] Synthesis Example 1 (Synthesis of perfluoroethercarboxylic acid ammonium salt A) After purging the air in a 1-L autoclave with nitrogen, 16.5 g of dehydrated tetramethylurea and 220 g of diethylene glycol dimethyl ether were charged and cooled. 38.5 g of carbonyl fluoride was charged, followed by 100 g of hexafluoropropylene oxide, which was then stirred. Subsequently, 38.5 g of carbonyl fluoride and 100 g of hexafluoropropylene oxide were additionally charged. Then, equal amounts of carbonyl fluoride and hexafluoropropylene oxide were further charged. After completion of the reaction, the reaction mixture was removed and separated to obtain the lower layer reaction product.

[0531] A 6-L autoclave was charged with 1,000 mL of tetraglyme and 75 g of CsF, and the atmosphere inside the autoclave was replaced with nitrogen. The autoclave was then cooled, and 2,100 g of the reaction product obtained above was charged. Hexafluoropropylene oxide was then introduced into the autoclave to initiate the reaction. Finally, 1,510 g of hexafluoropropylene oxide was charged. The contents were then removed, and the upper and lower layers were separated using a separatory funnel. The upper layer weighed 1,320 g, and the lower layer weighed 3,290 g. The lower layer was rectified and isolated.

[0532] Next, 1000 g of purified water was added to 1000 g of the isolated target product to carry out hydrolysis. The liquids were then separated using a separatory funnel, and the organic layer (lower layer) was collected. The collected solution was washed with aqueous sulfuric acid. The resulting solution was further purified by simple distillation. After purification, 500 g of the above-obtained simple distillate was added dropwise to an aqueous solution prepared by mixing the obtained compound, 76 g of 28% by mass aqueous ammonia solution, and 600 g of purified water. After the dropwise addition was completed, 28% by mass aqueous ammonia solution was added to adjust the pH to 7. This was freeze-dried to obtain perfluoroether carboxylic acid ammonium salt A.

[0533] Production Example 1 (Preparation of Fluorine Resin Powder A-1) Coarse homo-PTFE powder obtained by suspension polymerization of TFE monomer alone was crushed in a crusher to obtain 35 g of PTFE molding powder (standard specific gravity (SSG): 2.159, melting point: 345.0°C). This powder was compression molded in a φ100 mm mold at 30 MPa for 1 minute and then baked at 370°C for 3 hours to obtain a molded product. The molded product obtained was cut and then crushed in a crusher to obtain fluororesin powder A-1. The melting point of fluororesin powder A-1 was 328°C, the average secondary particle size was 23 μm, D10 was 8 μm, D90 was 48 μm, the apparent density was 0.64 g / ml, and the maximum linear length was 94 μm.

[0534] Production Example 2 (Preparation of Fluorine Resin Powder A-2) The molded article obtained in the same manner as in Production Example 1 was cut and then pulverized in a pulverizer to obtain fluororesin powder A-2, which had a melting point of 328°C, an average secondary particle size of 148 μm, D10 of 96 μm, D90 of 212 μm, and an apparent density of 1.03 g / ml.

[0535] Production Example 3 (Preparation of Fluorine Resin Powder B-1) The homo-PTFE coarse powder obtained by suspension polymerization of TFE monomer alone was pulverized in a pulverizer to obtain fluororesin powder B-1. The apparent density of fluororesin powder B-1 was 0.34 g / ml, the average secondary particle size was 24 μm, D90 was 55 μm, the standard specific gravity (SSG) was 2.163, the melting point was 345.0°C, and the maximum linear length was 112 μm.

[0536] Production Example 4 (Preparation of Fluorine Resin Powder B-2) The modified PTFE coarse powder obtained by suspension polymerization of TFE and perfluoropropyl vinyl ether (PPVE) was pulverized in a pulverizer to obtain fluororesin powder B-2. The apparent density of fluororesin powder B-2 was 0.33 g / ml, the average secondary particle size was 28 μm, D90 was 77 μm, the standard specific gravity (SSG) was 2.168, the melting point was 341.5°C, the amount of PPVE units was 0.09 mass%, and the maximum linear length was 156 μm.

[0537] Production Example 5 (Preparation of Fluorine Resin Powder B-3) In a 6 L stainless steel autoclave equipped with a stirring blade, perfluoroether carboxylic acid ammonium salt A was used to obtain an aqueous dispersion of modified PTFE consisting of TFE units and perfluoro(propyl vinyl ether) (PPVE) units by a known emulsion polymerization method, and then coagulation and drying were carried out by a known method to obtain fluororesin powder B-3. The resulting fluororesin powder B-3 had an apparent density of 0.46 g / ml, an average secondary particle diameter of 460 μm, a standard specific gravity (SSG) of 2.169, a melting point of 334.6°C, a PPVE unit content of 0.14 mass%, and a maximum linear length of 1379 μm.

[0538] Production Example 6 (Preparation of Fluorine Resin Powder B-4) In a 6 L stainless steel autoclave equipped with a stirring blade, a PFA aqueous dispersion containing PFA particles composed of TFE units and perfluoro(propyl vinyl ether) (PPVE) units was obtained by a known emulsion polymerization method using perfluoroether carboxylic acid ammonium salt A. The resulting PFA aqueous dispersion was coagulated to obtain fluororesin powder B-4. The average secondary particle size was 1.5 μm, the MFR was 28 g / 10 min, the melting point was 314°C, the PPVE unit content was 1.4 mol%, and the maximum linear length was 27 μm.

[0539] Production Example 7 (Preparation of Fluorine Resin Powder B-6) The homo-PTFE coarse powder obtained by suspension polymerization of TFE monomer alone was pulverized in a pulverizer to obtain fluororesin powder B-6. The apparent density of fluororesin powder B-6 was 0.39 g / ml, the average secondary particle size was 31 μm, D90 was 204 μm, the melting point was 343°C, and the maximum linear length was 307 μm.

[0540] The carbon black and boron nitride used in the examples are as follows: Carbon black 1: BET specific surface area = 225 m 2 / g, DBP oil absorption = 105cc / 100g, average primary particle size = 16nm Carbon black 2: BET specific surface area = 214 m 2 / g, DBP oil absorption = 175cc / 100g, average primary particle size = 37nm Boron nitride: BET specific surface area = 5.0 m 2 / g, tap density = 0.3 g / cm 3

[0541] Example 1 40 g of fluororesin powder A-1, 45 g of fluororesin powder B-2, and 15 g of glass fiber (PF E-001, manufactured by Nitto Boseki Co., Ltd.) were mixed in a Wonder Crusher WC-3 at 6900 rpm for 60 seconds to obtain a PTFE powder (fluororesin composition). The resulting PTFE powder had an apparent density of 0.45 g / ml and an angle of repose of 34°, demonstrating excellent handleability. The PTFE powder contained 99.959 mass% TFE units and 0.041 mass% PPVE units relative to the total polymerized units. The melting points of the PTFE powder were 329°C and 342°C, a tensile strength at break of 15 MPa, and a tensile strain at break of 342%. The properties of the resulting PTFE powder are shown in Table 1.

[0542] Example 2 A PTFE powder was obtained in the same manner as in Example 1 using 35 g of fluororesin powder A-1, 40 g of fluororesin powder B-2, 10 g of fluororesin powder B-4, and 15 g of glass fiber (PF E-001, manufactured by Nitto Boseki Co., Ltd.). The apparent density of the obtained PTFE powder was 0.48 g / ml, the angle of repose was 38°, and the handling ability was excellent. The PTFE powder contained 99.604 mass% of TFE units and 0.396 mass% of PPVE units based on the total polymerized units. The melting points of the PTFE powder were 315°C, 329°C, and 342°C, the tensile strength at break was 16 MPa, and the tensile strain at break was 365%. The properties of the obtained PTFE powder are shown in Table 1.

[0543] Example 3 A PTFE powder was obtained in the same manner as in Example 1 using 40 g of fluororesin powder A-1, 35 g of fluororesin powder B-1, 10 g of fluororesin powder B-4, and 15 g of glass fiber (PF E-001, manufactured by Nitto Boseki Co., Ltd.). The apparent density of the obtained PTFE powder was 0.44 g / ml, the angle of repose was 38°, and the handling ability was excellent. The PTFE powder also contained 99.641 mass% of TFE units and 0.359 mass% of PPVE units relative to the total polymerized units. The melting points of the PTFE powder were 315°C, 329°C, and 345°C, the tensile strength at break was 16 MPa, and the tensile strain at break was 401%. The properties of the obtained PTFE powder are shown in Table 1.

[0544] Example 4 A PTFE powder was obtained in the same manner as in Example 1 using 40 g of fluororesin powder A-1, 40 g of fluororesin powder B-2, 15 g of glass fiber (PF E-001 manufactured by Nitto Boseki Co., Ltd.), and 5 g of graphite (CPB manufactured by Nippon Graphite Industries Co., Ltd.). The apparent density of the obtained PTFE powder was 0.49 g / ml, the angle of repose was 38°, and it was easy to handle. The PTFE powder contained 99.964 mass% of TFE units and 0.036 mass% of PPVE units based on the total polymerized units. The melting points of the PTFE powder were 329°C and 342°C, the tensile strength at break was 9 MPa, and the tensile strain at break was 80%. The properties of the obtained PTFE powder are shown in Table 1.

[0545] Example 5 A PTFE powder was obtained in the same manner as in Example 1 using 40 g of fluororesin powder A-1, 45 g of fluororesin powder B-2, and 15 g of bronze powder (Bro-AT-200, manufactured by Fukuda Metal Foil & Powder Co., Ltd.). The apparent density of the obtained PTFE powder was 0.53 g / ml, the angle of repose was 34°, and it was easy to handle. The PTFE powder contained 99.959 mass% of TFE units and 0.041 mass% of PPVE units relative to the total polymerized units. The melting points of the PTFE powder were 329°C and 342°C, the tensile strength at break was 14 MPa, and the tensile strain at break was 364%. The properties of the obtained PTFE powder are shown in Table 1.

[0546] Example 6 A PTFE powder was obtained in the same manner as in Example 1, except that 45 g of fluororesin powder A-1, 40 g of fluororesin powder B-3, and 15 g of glass fiber (PF E-001, manufactured by Nitto Boseki Co., Ltd.) were used, and the rotation speed was changed to 2900 rpm. The apparent density of the obtained PTFE powder was 0.43 g / ml, the angle of repose was 35°, and it was easy to handle. The PTFE powder contained 99.944 mass% of TFE units and 0.056 mass% of PPVE units based on the total polymerized units. The melting points of the PTFE powder were 329°C and 336°C, the tensile strength at break was 11 MPa, and the tensile strain at break was 283%. The properties of the obtained PTFE powder are shown in Table 1.

[0547] Example 7 A PTFE powder was obtained in the same manner as in Example 1 using 65 g of fluororesin powder A-2, 25 g of fluororesin powder B-6, and 10 g of carbon black 1. The apparent density of the obtained PTFE powder was 0.43 g / ml, the angle of repose was 23°, and it was easy to handle. The melting points of the PTFE powder were 327°C and 343°C, the tensile strength at break was 11 MPa, the tensile strain at break was 26%, and the volume resistivity was 1.4 Ω·cm. The residue generated by thermal decomposition at 600°C under a nitrogen atmosphere was 9.1% by mass. The properties of the obtained PTFE powder are shown in Table 1.

[0548] Example 8 PTFE powder was obtained in the same manner as in Example 1 using 72 g of fluororesin powder A-2, 25 g of fluororesin powder B-6, and 3 g of carbon black 1. The apparent density of the obtained PTFE powder was 0.54 g / ml, the angle of repose was 21°, and it was easy to handle. The melting points of the above PTFE powder were 327°C and 343°C, the tensile strength at break was 14 MPa, the tensile strain at break was 55%, and the volume resistivity was 8.0 Ω·cm. The residue generated by thermal decomposition at 600°C under a nitrogen atmosphere was 5.4 mass%. The properties of the obtained PTFE powder are shown in Table 1.

[0549] Example 9 A PTFE powder was obtained in the same manner as in Example 1 using 20 g of fluororesin powder A-2, 70 g of fluororesin powder B-6, and 10 g of carbon black 2. The apparent density of the obtained PTFE powder was 0.48 g / ml, the angle of repose was 20°, and it was easy to handle. The melting points of the PTFE powder were 327°C and 343°C, the tensile strength at break was 14 MPa, the tensile strain at break was 158%, and the volume resistivity was 1.6 Ω·cm. The residue generated by thermal decomposition at 600°C under a nitrogen atmosphere was 11.9 mass%. The properties of the obtained PTFE powder are shown in Table 1.

[0550] Example 10 PTFE powder was obtained in the same manner as in Example 1 using 40 g of fluororesin powder A-2, 50 g of fluororesin powder B-6, and 10 g of carbon black 1. The apparent density of the obtained PTFE powder was 0.43 g / ml, the angle of repose was 34°, and it was easy to handle. The melting points of the PTFE powder were 327°C and 343°C, the tensile strength at break was 10 MPa, the tensile strain at break was 17%, and the volume resistivity was 5.1 Ω·cm. The residue generated by thermal decomposition at 600°C under a nitrogen atmosphere was 9.8% by mass. The properties of the obtained PTFE powder are shown in Table 1.

[0551] Example 11 PTFE powder was obtained in the same manner as in Example 1 using 40 g of fluororesin powder A-2, 45 g of fluororesin powder B-6, and 15 g of carbon black 2. The apparent density of the obtained PTFE powder was 0.34 g / ml, the angle of repose was 28°, and it was easy to handle. The melting points of the PTFE powder were 327°C and 343°C, the tensile strength at break was 10 MPa, the tensile strain at break was 16%, and the volume resistivity was 0.6 Ω·cm. The residue generated by thermal decomposition at 600°C under a nitrogen atmosphere was 16.8 mass%. The properties of the obtained PTFE powder are shown in Table 1.

[0552] Example 12 PTFE powder was obtained in the same manner as in Example 1 using 70 g of fluororesin powder A-2, 25 g of fluororesin powder B-6, and 5 g of carbon black 2. The apparent density of the obtained PTFE powder was 0.46 g / ml, the angle of repose was 29°, and it was easy to handle. The melting points of the above PTFE powder were 327°C and 343°C, the tensile strength at break was 17 MPa, the tensile strain at break was 140%, and the volume resistivity was 3.1 Ω·cm. The residue generated by thermal decomposition at 600°C under a nitrogen atmosphere was 7.4 mass%. The properties of the obtained PTFE powder are shown in Table 1.

[0553] Example 13 Using 74 g of fluororesin powder A-2, 25 g of fluororesin powder B-6, and 1 g of carbon black 1, a PTFE powder was obtained in the same manner as in Example 1. The obtained PTFE powder had an apparent density of 0.60 g / ml and an angle of repose of 22°, and was easy to handle. The melting points of the PTFE powder were 327°C and 343°C, a tensile strength at break of 17 MPa, a tensile strain at break of 167%, and a volume resistivity of 2.0 × 10 2 The resistivity was Ω·cm. The residue generated by thermal decomposition at 600°C in a nitrogen atmosphere was 8.1 mass%. The properties of the obtained PTFE powder are shown in Table 1.

[0554] Example 14 PTFE powder was obtained in the same manner as in Example 1 using 69 g of fluororesin powder A-2, 3 g of fluororesin powder B-4, 25 g of fluororesin powder B-6, and 3 g of carbon black 2. The apparent density of the obtained PTFE powder was 0.51 g / ml, the angle of repose was 26°, and it was easy to handle. Furthermore, the PTFE powder contained 99.8923 mass% of TFE units and 0.1077 mass% of PPVE units relative to the total polymerized units. The melting points of the PTFE powder were 315°C, 327°C, and 343°C, the tensile strength at break was 18 MPa, the tensile strain at break was 211%, and the volume resistivity was 9.2 Ω·cm. The residue generated by thermal decomposition at 600°C under a nitrogen atmosphere was 4.8 mass%. The properties of the obtained PTFE powder are shown in Table 1.

[0555] Example 15 PTFE powder was obtained in the same manner as in Example 1 using 65 g of fluororesin powder A-2, 25 g of fluororesin powder B-6, and 10 g of boron nitride. The apparent density of the obtained PTFE powder was 0.56 g / ml, the angle of repose was 30°, and it was easy to handle. The melting points of the PTFE powder were 327°C and 343°C, the tensile strength at break was 10 MPa, the tensile strain at break was 42%, and the thermal conductivity was 0.72 W / m K. The residue generated by thermal decomposition at 600°C under a nitrogen atmosphere was 13.9 mass%. The properties of the obtained PTFE powder are shown in Table 1.

[0556] Example 16 A PTFE powder was obtained in the same manner as in Example 1 using 72 g of fluororesin powder A-2, 25 g of fluororesin powder B-6, and 3 g of boron nitride. The apparent density of the obtained PTFE powder was 0.72 g / ml, the angle of repose was 31°, and it was easy to handle. The melting points of the PTFE powder were 327°C and 343°C, the tensile strength at break was 15 MPa, the tensile strain at break was 154%, and the thermal conductivity was 0.32 W / m K. The residue generated by thermal decomposition at 600°C under a nitrogen atmosphere was 10.9 mass%. The properties of the obtained PTFE powder are shown in Table 1.

[0557] Comparative Example 1 A PTFE powder was obtained in the same manner as in Example 1 using 85 g of fluororesin powder A-1 and 15 g of glass fiber (PF E-001 manufactured by Nitto Boseki Co., Ltd.). The apparent density of the obtained PTFE powder was 0.62 g / ml, the angle of repose was 44°, and it was poor in handleability. The PTFE powder contained 100 mass% TFE units relative to all polymerized units. The melting point of the PTFE powder was 329°C, the tensile strength at break was 6 MPa, and the tensile strain at break was 71%. The properties of the obtained PTFE powder are shown in Table 1.

[0558] Comparative Example 2 A PTFE powder was obtained in the same manner as in Example 1 using 85 g of fluororesin powder A-1 and 15 g of graphite (CPB manufactured by Nippon Graphite Industries Co., Ltd.). The apparent density of the obtained PTFE powder was 0.37 g / ml and the angle of repose was 43°, making it difficult to handle. The PTFE powder contained 100 mass% TFE units relative to all polymerized units. The melting point of the PTFE powder was 329°C, the tensile strength at break was 7 MPa, and the tensile strain at break was 17%. The properties of the obtained PTFE powder are shown in Table 1.

[0559] [Table 1]

Claims

1. A fluororesin A that does not exhibit melting fluidity and has a history of being heated to a temperature above its melting point, A fluororesin B selected from the group consisting of fluororesins that exhibit melt fluidity and fluororesins that do not exhibit melt fluidity and have no history of being heated to a temperature above their melting point, Including filler, A fluororesin composition that does not exhibit melting fluidity.

2. A fluororesin A that does not exhibit melt fluidity and has a history of being heated to a temperature above its melting point, Including filler, A fluororesin composition that does not exhibit melting fluidity.

3. The fluororesin composition according to claim 1 or 2, having one or more melting points in the temperature range below 333°C and one or more melting points in the temperature range of 333 to 360°C.

4. The fluororesin composition according to claim 1 or 2, comprising tetrafluoroethylene units and modified monomer units based on modified monomers copolymerizable with tetrafluoroethylene.

5. The fluororesin composition according to claim 4, wherein the amount of the modified monomer units is 1.0% by mass or less with respect to the total polymerization units constituting the fluororesin composition.

6. The fluororesin composition according to claim 1 or 2, wherein the fluororesin A is polytetrafluoroethylene.

7. The fluororesin composition according to claim 1 or 2, wherein the content of fluororesin A in the fluororesin composition is 40% by mass or more.

8. The fluororesin composition according to claim 1 or 2, wherein the content of fluororesin A in the fluororesin composition is 50% by mass or more.

9. The fluororesin composition according to claim 1 or 2, wherein the D90 of the fluororesin A is 10 μm or more and 600 μm or less.

10. The fluororesin composition according to claim 1 or 2, wherein the fluororesin A is pulverized by at least one type of pulverizer selected from the group consisting of an air jet mill, a hammer mill, a force mill, and a stone mill type pulverizer.

11. The fluororesin exhibiting melt fluidity is the fluororesin composition according to claim 1 or 2, wherein the melt flow rate is 0.25 g / 10 min or more.

12. The fluororesin composition according to claim 1 or 2, wherein the fluororesin exhibiting melt fluidity has a melting point of 320°C or lower.

13. The fluororesin composition according to claim 1 or 2, wherein fluororesin B is a fluororesin exhibiting the molten fluidity, and the fluororesin composition further comprises a fluororesin C that does not exhibit molten fluidity and has a portion that has not been heated to a temperature above its melting point.

14. The fluororesin composition according to claim 1 or 2, wherein the apparent density is 0.40 g / ml or more.

15. The fluororesin composition according to claim 1 or 2, wherein the angle of repose is less than 40°.

16. The fluororesin composition according to claim 1 or 2, wherein the average secondary particle diameter is 5 to 700 μm.

17. The fluororesin composition according to claim 1 or 2, wherein the maximum linear length of the particles of fluororesin A is smaller than the maximum linear length of the particles of fluororesin B.

18. The fluororesin composition according to claim 1 or 2, wherein the filler is at least one selected from the group consisting of glass fiber, glass beads, carbon fiber, spherical carbon, carbon black, graphite, silica, alumina, mica, silicon carbide, boron nitride, titanium oxide, bismuth oxide, cobalt oxide, molybdenum disulfide, bronze, gold, silver, copper, and nickel.

19. The fluororesin composition according to claim 1 or 2, wherein the filler is a conductive filler.

20. The fluororesin composition according to claim 19, wherein the conductive filler is carbon black.

21. The fluororesin composition according to claim 1 or 2, which is a powder.

22. The fluororesin composition according to claim 1 or 2, which is a powder for compression molding or a powder for ram extrusion molding.

23. The fluororesin composition according to claim 1 or 2, wherein the tensile breaking strength is 8 MPa or more.

24. A molded article obtained by compression molding and firing, or by ram extrusion molding, of the fluororesin composition according to claim 1 or 2.

25. A fluororesin composition having one or more endothermic peaks in the range of 320 to 335°C, When thermally decomposed at 600°C under a nitrogen atmosphere, a residue of 15% by mass or less is produced relative to the fluororesin composition. A fluororesin composition exhibiting conductivity or a thermal conductivity of 0.3 W / m·K or higher.

26. Furthermore, the fluororesin composition according to claim 25, having one or more endothermic peaks in the range above 335°C.

27. The fluororesin composition according to claim 25 or 26, further comprising a conductive filler or a thermally conductive filler.

28. Volume resistivity is 10 ４ The fluororesin composition according to claim 25 or 26, wherein the value is Ω·cm or less.

29. The fluororesin composition according to claim 25 or 26, wherein the apparent density is 0.40 g / ml or more.

30. The fluororesin composition according to claim 25 or 26, wherein the angle of repose is less than 40°.

31. The fluororesin composition according to claim 25 or 26, which is a powder for ram extrusion molding.

32. The fluororesin composition according to claim 25 or 26, wherein the tensile breaking strength is 8 MPa or more.

33. A fluororesin composition according to any one of claims 1, 2, 25, and 26, which is not for porous applications.

34. The fluororesin composition comprises tetrafluoroethylene units and modified monomer units based on modified monomers copolymerizable with tetrafluoroethylene, The fluororesin composition contains 99.0% by mass or more of the tetrafluoroethylene units and 0.010 to 0.10% by mass of the modified monomer units, with respect to the total polymerization units comprising the fluororesin composition. The fluororesin composition according to any one of claims 1, 2, 25, and 26, wherein the modified monomer is at least one selected from the group consisting of perfluoroolefins, perhaloolefins, perfluorovinyl ethers, and perfluoroallyl ethers.

35. The fluororesin composition according to any one of claims 1, 2, 25, and 26, wherein D90 is 10 μm or more and 800 μm or less.

36. The fluororesin composition according to any one of claims 1, 2, 25, and 26, further comprising a low molecular weight fluorine-containing compound, wherein the content of the low molecular weight fluorine-containing compound is 1 ppm by mass or less relative to the fluororesin composition.

37. The fluororesin composition according to any one of claims 1, 2, 25, and 26, which is granulated.

38. The fluororesin composition according to any one of claims 1, 2, 25, and 26, which is a powder for compression molding at a pressure of 50 MPa or less.

39. The fluororesin composition according to any one of claims 1, 2, 25, and 26, wherein the tensile fracture strain is 300% or more.

40. A fluororesin composition according to any one of claims 1, 2, 25, and 26, used in at least one selected from the group consisting of lining sheets, packings, gaskets, diaphragm valves, heat-resistant wires, heat-resistant insulating tapes, release sheets, sealing materials, casings, sleeves, bellows, hoses, piston rings, butterfly valves, rectangular tanks, and wafer carriers.