Fluororesin composition and molded article

Abstract

To provide: a fluororesin composition which has excellent tensile characteristics even though it contains a fluororesin which has been heated to a temperature equal to or higher than the melting point; and a molded body obtainable from the fluororesin composition.SOLUTION: A fluororesin composition that does not show melt fluidity contains: a fluororesin A which has been heated to a temperature equal to or higher than the melting point and which does not show melt fluidity; and a fluororesin B which shows melt fluidity.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] Polytetrafluoroethylene (PTFE) that has been heated to a temperature above its melting point and has a heating history for molding or the like cannot obtain sufficient physical properties even if it is used again as a molding material as it is, so recycling in molding applications has been partially stopped.

[0003] Patent Documents 1 and 2 describe technologies related to the recycling of PTFE pulverized after firing and heated PTFE.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present disclosure is to provide a fluororesin composition having excellent tensile properties and a molded article obtained from the above fluororesin composition, even though it contains a fluororesin having a heating history at a temperature above its melting point.

Means for Solving the Problems

[0006] The present disclosure provides a fluororesin composition that does not exhibit melt fluidity and contains a fluororesin A that does not exhibit melt fluidity and has a heating history at a temperature above its melting point and a fluororesin B that exhibits melt fluidity.

[0007] The fluororesin A is preferably polytetrafluoroethylene.

[0008] Fluororesin B preferably has an MFR of 0.25 g / 10 min or more.

[0009] Fluororesin B is preferably a fluororesin having a melting point of 320°C or less.

[0010] The above fluororesin composition preferably further contains a fluororesin C that does not exhibit melt fluidity and has a portion without a history of heating to a temperature above the melting point.

[0011] The above fluororesin composition 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.

[0012] The above fluororesin composition contains a tetrafluoroethylene unit and a modified monomer unit based on a modified monomer copolymerizable with tetrafluoroethylene, and preferably the amount of the above modified monomer unit is 1.0% by mass or less based on all polymerization units.

[0013] The above fluororesin composition preferably has an average secondary particle diameter of 5 to 700 μm.

[0014] The content of the low-molecular-weight fluorine-containing compound is preferably 1 mass ppm or less based on the above fluororesin composition.

[0015] The above fluororesin composition is preferably in powder form.

[0016] The above fluororesin composition is preferably a powder for compression molding.

[0017] The above fluororesin composition preferably has a tensile fracture strength of 10 MPa or more.

[0018] The above fluororesin composition preferably has a tensile fracture strain of 150% or more.

[0019] The present disclosure also provides a molded article obtained by compression molding and firing the above fluororesin composition.

Advantages of the Invention

[0020] According to the present disclosure, it is possible to provide a fluororesin composition having excellent tensile properties and a molded article obtained from the above fluororesin composition, even though it contains a fluororesin having a history of being heated to a temperature equal to or higher than the melting point.

Embodiments for Carrying Out the Invention

[0021] Hereinafter, the present disclosure will be specifically described.

[0022] The present disclosure provides a fluororesin composition that does not exhibit melt fluidity, which 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 the melting point, and a fluororesin B that exhibits melt fluidity. Since the fluororesin composition of the present disclosure contains a fluororesin B that exhibits melt fluidity, it has excellent tensile properties (for example, tensile breaking strength, tensile breaking strain) even though it contains a fluororesin A that has a history of being heated to a temperature equal to or higher than the melting point. This effect is considered to be due to the fact that at the time of molding, the interface between the particles of the fluororesin A is filled with the fluororesin B.

[0023] In the fluororesin composition of the present disclosure, as a method for distinguishing between the fluororesin A and the fluororesin B, for example, the above fluororesin composition is placed on a hot stage and observed with a microscope while heating at a rate of 5°C / min, and a method of determining whether the particles are particles of the fluororesin A or B based on whether the shape of the particles is maintained can be mentioned.

[0024] The above fluororesin A has a history of being heated to a temperature equal to or higher than the melting point. Examples of the above heating include heating for molding, heat treatment, etc.

[0025] The fluororesin A preferably has a melting point of 100°C or higher and less than 333°C, more preferably less than 332°C, and still more preferably less than 331°C. The lower limit is not limited, but it is more preferably 140°C, and even more preferably 180°C or higher.

[0026] Fluororesin A preferably has one or more melting points in the temperature range below 333°C. The temperature range below 333°C is more preferably below 332°C, even more preferably below 331°C, and preferably 100°C or higher, more preferably 140°C or higher, and even more preferably 180°C or higher. Having a melting point within the above range indicates that there is a history of heating to a temperature above the melting point. Fluororesin A may also have a melting point in the temperature range of 333°C or higher.

[0027] In this specification, the melting point of the fluororesin is the temperature corresponding to the minimum point in the melting heat curve obtained by performing differential scanning calorimetry [DSC] at a heating rate of 10°C / min using X-DSC7000 (manufactured by Hitachi High-Tech Science Corporation). When there are two or more minimum points in one melting peak, each is regarded as the melting point.

[0028] Fluororesin A does not exhibit melt fluidity. In this specification, not exhibiting melt fluidity means that the melt flow rate (MFR) is 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. In this specification, MFR is the value obtained as the mass (g / 10 min) of the polymer flowing out per 10 minutes from a nozzle with an inner diameter of 2.095 mm and a length of 8 mm at the measurement temperature (for example, 372°C for PFA and FEP, 297°C for ETFE) and load (for example, 5 kg for PFA, FEP, and ETFE) determined according to the type of fluororesin using a melt indexer in accordance with ASTM D1238. In the case of PTFE, it is the value obtained by measuring under the same measurement conditions as PFA.

[0029] Also, 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 1 hour or more, if the reduction rate of the thickness after heating with respect to the thickness before heating is less than 20%, or if the thickness after heating increases compared to the thickness before heating, it also means that the fluororesin does not exhibit melt fluidity.

[0030] As the fluororesin A, polytetrafluoroethylene [PTFE] is preferable. The above PTFE may be high molecular weight PTFE.

[0031] The above PTFE as the fluororesin A may be a homopolymer of TFE, or a modified PTFE containing a polymerization unit based on 99.0% by mass or more of TFE and a polymerization unit based on 1.0% by mass or less of a modified monomer (hereinafter also referred to as "modified monomer unit"). The above modified PTFE may consist only of a polymerization unit based on TFE and a modified monomer unit.

[0032] For the above modified PTFE, the content of the modified monomer unit is preferably in the range of 0.00001 to 1.0% by mass based on all the polymerization units. As the lower limit of the content of the modified monomer unit, 0.0001% by mass is more preferable, 0.001% by mass is further preferable, 0.005% by mass is even more preferable, and 0.010% by mass is particularly more preferable. As the upper limit of the content of the modified monomer unit, 0.90% by mass is preferable, 0.50% by mass is more preferable, 0.40% by mass is further preferable, 0.30% by mass is even more preferable, 0.20% by mass is particularly more preferable, and 0.10% by mass is particularly preferable. In this specification, the above modified monomer unit means a part of the molecular structure of PTFE that is derived from the modified monomer.

[0033] The above-mentioned modified monomer is not particularly limited as long as it can copolymerize with TFE. For example, 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. may be mentioned. Further, the modified monomer used may be one kind or a plurality of kinds.

[0034] The above-mentioned perfluorovinyl ether is not particularly limited. For example, the following general formula (A): CF2=CF-ORf (A) (In the formula, Rf represents a perfluoro organic group.) Perfluoro unsaturated compounds represented by the like may be mentioned. In the present specification, the above-mentioned "perfluoro organic group" means an organic group in which all hydrogen atoms bonded to carbon atoms are substituted by fluorine atoms. The above-mentioned perfluoro organic group may have an ether oxygen.

[0035] As the above-mentioned perfluorovinyl ether, for example, in the above general formula (A), perfluoro(alkyl vinyl ether) [PAVE] in which Rf is a perfluoroalkyl group having 1 to 10 carbon atoms may be mentioned. The number of carbon atoms of the above-mentioned perfluoroalkyl group is preferably 1 to 5.

[0036] Examples of the perfluoroalkyl group in the above-mentioned PAVE include a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, a perfluorohexyl group, etc.

[0037] As the above-mentioned perfluorovinyl ether, further, in the above general formula (A), those in which Rf is a perfluoro(alkoxyalkyl) group having 4 to 9 carbon atoms, and Rf is the following formula:

[0038]

Chemical formula

[0039] (In the formula, m represents an integer of 0 or 1 to 4.) A group represented by the formula, where Rf is the following formula:

[0040] [Chemical formula]

[0041] (In the formula, n represents an integer of 1 to 4.) Examples thereof include those represented by the formula.

[0042] (Perfluoroalkyl)ethylene (PFAE) is not particularly limited, and examples thereof include (perfluorobutyl)ethylene (PFBE), (perfluorohexyl)ethylene, and the like.

[0043] Examples of the perfluoroallyl ether include, for example, the general formula (B): CF2=CF-CF2-ORf 1 (B) (In the formula, Rf 1 represents a perfluoro organic group.) Fluoromonomers represented by the formula are included.

[0044] The above Rf 1 is preferably a perfluoroalkyl group having 1 to 10 carbon atoms or a perfluoroalkoxyalkyl group having 1 to 10 carbon atoms. As the above perfluoroallyl ether, 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 is preferable, 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 is more preferable, and CF2=CF-CF2-O-CF2CF2CF3 is even more preferable.

[0045] The above-mentioned PTFE as fluororesin A preferably has a standard specific gravity (SSG) of 2.280 or less, more preferably 2.10 or less. Also, it is preferably 1.50 or more, more preferably 1.60 or more. The above SSG is measured by the water displacement method in accordance with ASTM D-792 using a sample molded in accordance with ASTM D 4895-89.

[0046] The above-mentioned PTFE (high molecular weight PTFE) as fluororesin A usually has non-melt secondary processability. The above non-melt secondary processability means the property 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 property of not flowing easily even in the melting temperature region.

[0047] One of the melting points of the above-mentioned PTFE (high molecular weight PTFE) as fluororesin A is preferably 310°C or higher, more preferably 320°C or higher, and preferably less than 333°C. It may also have a melting point in the temperature range of 333°C or higher.

[0048] The fluororesin composition of the present disclosure may contain particles of fluororesin A. The particles of the above-mentioned fluororesin A may be secondary particles of fluororesin A.

[0049] The particles of the above-mentioned fluororesin A preferably have an average secondary particle diameter of 1 to 200 μm. The above average secondary particle diameter is more preferably 5 μm or more, further preferably 10 μm or more, more preferably 150 μm or less, further 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 dry at a vacuum pressure of 20 mH2O using a laser diffraction particle size distribution analyzer (LS13 320) manufactured by Beckman Coulter, and is assumed to be equal to the particle diameter corresponding to 50% of the particle size distribution integration (volume basis).

[0050] The particles of the fluororesin A preferably have a D90 of 10 μm or more, more preferably 30 μm or more, still more preferably 50 μm or more, and preferably 600 μm or less, more preferably 500 μm or less, and still more preferably 400 μm or less. The above D90 is measured dry using a laser diffraction particle size distribution analyzer (LS13 320) manufactured by Beckman Coulter at a vacuum pressure of 20 mH2O and is considered equal to the particle diameter corresponding to 90% of the cumulative particle size distribution (volume basis).

[0051] The particles of the fluororesin A can be obtained, for example, by crushing the cutting chips of a molded article obtained by compression molding and firing a fluororesin that does not exhibit melt fluidity without a history of heating to a temperature above the melting point. The above crushing can be performed using a crusher or the like. After coarse crushing, it may be refined. The shape of the compression molding is not particularly limited. The firing temperature may be equal to or higher than the melting point of the fluororesin. The crusher is not particularly limited as long as it can crush (preferably refine) the cutting chips. Examples include an air jet mill, a hammer mill, a force mill, a mortar type crusher, a cryogenic crusher, and the like.

[0052] The particles of the fluororesin A can also be obtained by heating a powder of a fluororesin that does not exhibit melt fluidity without a history of heating to a temperature above the melting point without compression molding and then crushing using a crusher. The crusher is the same as above.

[0053] The above fluororesin B 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, more preferably 1.00 g / 10 min or more. The above MFR may be 100 g / 10 min or less, preferably 80 g / 10 min or less.

[0054] 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 1 hour or longer, a reduction rate of the thickness after heating with respect to the thickness before heating of 20% or higher also means that the fluororesin exhibits melt fluidity.

[0055] It is preferable that the above fluororesin B has no history of being heated to a temperature equal to or higher than the melting point.

[0056] The fluororesin B preferably has a melting point of 100 to 340°C. The above melting point is more preferably 140°C or higher, still more preferably 160°C or higher, and also more preferably 336°C or lower, still more preferably 333°C or lower, even more preferably 332°C or lower, particularly preferably 331°C or lower, and especially preferably 330°C or lower.

[0057] The melting point of the fluororesin B can be measured by the above method. However, when the amount of the fluororesin B is small, for example, 5% by mass or less, with respect to the total of the fluororesin A and the fluororesin B, it may be difficult to detect by the above method. In that case, after holding at a temperature lower than the melting point of the fluororesin B (preferably 10°C or more lower than the above melting point) for 10 minutes during the temperature increase, the melting peak of the fluororesin B may be detected by increasing the temperature again at a rate of 10°C / min. It is also possible to increase the temperature by this method.

[0058] As the fluororesin B, at least one selected from the group consisting of a fluororesin having a melting point of 320°C or lower and low molecular weight polytetrafluoroethylene (low molecular weight PTFE) is preferable, and a fluororesin having a melting point of 320°C or lower is more preferable. As the fluororesin B, a perfluoro resin is also preferable.

[0059] Examples of the fluororesin having a melting point of 320°C or lower 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, Et / CTFE copolymer, 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, VdF / PAVE / TFE copolymer, etc. At least one selected from the group consisting of PFA, FEP, and ETFE is preferable, at least one selected from the group consisting of PFA and FEP is more preferable, and PFA is even more preferable.

[0060] The above PFA contains a TFE unit and a PAVE unit or a perfluoro(alkyl allyl ether) unit. Examples of the above PAVE include monomers in which, in the above general formula (A), Rf is a perfluoroalkyl group having 1 to 10 carbon atoms. Examples of the above perfluoro(alkyl allyl ether) include monomers in which, in the above general formula (B), Rf 1 is a perfluoroalkyl group having 1 to 10 carbon atoms.

[0061] Although the PFA is not particularly limited, a copolymer in which the molar ratio of the TFE unit to the PAVE unit or the perfluoro(alkylallyl ether) unit (TFE unit / (PAVE unit or perfluoro(alkylallyl ether) unit)) is 70 / 30 or more and less than 99 / 1 is preferable. A more preferable molar ratio is 70 / 30 or more and 98.9 / 1.1 or less, and an even more preferable molar ratio is 80 / 20 or more and 98.9 / 1.1 or less. The above PFA is a copolymer in which the polymerization units derived from monomers copolymerizable with TFE and PAVE or perfluoro(alkylallyl ether) are 0.1 to 10 mol% (the total of the TFE unit and the PAVE unit or the perfluoro(alkylallyl ether) unit is 90 to 99.9 mol%), more preferably 0.1 to 5 mol%, and particularly preferably 0.2 to 4 mol%.

[0062] Examples of the monomer copolymerizable with TFE and PAVE or perfluoro(alkylallyl ether) include HFP and Formula (I): CZ 1 Z 2 =CZ 3 (CF2) n Z 4 (wherein Z 1 、Z 2 and Z 3 are the same or different and each represents a hydrogen atom or a fluorine atom, and Z 4 represents a hydrogen atom, a fluorine atom or a chlorine atom, and n represents an integer of 2 to 10.) a vinyl monomer represented by the formula, and Formula (II): CF2=CF-OCH2-Rf 2 (wherein Rf 2 represents a perfluoroalkyl group having 1 to 5 carbon atoms.) an alkyl perfluorovinyl ether derivative represented by the formula, Formula (III): CZ 5 Z 6 =CZ 7 -CZ 8 Z 9 -O-Rf 3 (wherein, in the formula, Z 5 、Z 6 and Z 7 are the same or different and each represents a hydrogen atom, a chlorine atom or a fluorine atom, and 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 represented by the formula include CH2=CFCF2-O-Rf 3 , CF2=CFCH2-O-Rf 3 , CH2=CHCF2-O-Rf 3 (wherein Rf 3 is the same as the above formula (III)) and the like are preferably mentioned. In addition, examples of the monomer copolymerizable with TFE and PAVE or perfluoro(alkyl allyl ether) further include unsaturated monocarboxylic acids, unsaturated dicarboxylic acids, acid anhydrides of unsaturated dicarboxylic acids, such as itaconic acid, itaconic anhydride, citraconic anhydride, and 5-norbornene-2,3-dicarboxylic anhydride.

[0063] The above PFA preferably has a melting point of 180 to 320°C, more preferably 230 to 320°C, and even more preferably 280 to 320°C.

[0064] The above 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, even more preferably 1.0 g / 10 min or more, and also 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 as the mass (g / 10 min) of the polymer flowing out per 10 minutes from a nozzle having 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 using a melt indexer in accordance with ASTM D1238.

[0065] The above FEP is not particularly limited, but 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 is preferred. 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 above FEP is preferably a copolymer in which the polymerization units derived from monomers copolymerizable with TFE and HFP are 0.1 to 10 mol% (the total of TFE units and HFP units is 90 to 99.9 mol%), more preferably 0.1 to 5 mol%, and particularly preferably 0.2 to 4 mol%.

[0066] Examples of the monomers copolymerizable with TFE and HFP include PAVE, the monomer represented by formula (III), alkyl perfluorovinyl ether derivatives represented by formula (II), and the like. In addition, examples of the monomers copolymerizable with TFE and HFP further include unsaturated monocarboxylic acids, unsaturated dicarboxylic acids, acid anhydrides of unsaturated dicarboxylic acids, such as itaconic acid, itaconic anhydride, citraconic anhydride, and 5-norbornene-2,3-dicarboxylic anhydride.

[0067] The above FEP preferably has a melting point of 150 to 320°C, more preferably 200 to 320°C, and even more preferably 240 to 320°C.

[0068] The above 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, even more preferably 1.0 g / 10 min or more, and also more preferably 80 g / 10 min or less, even more preferably 60 g / 10 min or less. The MFR of FEP is a value obtained as the mass (g / 10 min) of the polymer flowing out per 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 using a melt indexer in accordance with ASTM D1238.

[0069] As the above-mentioned ETFE, 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 is preferable. A more preferable molar ratio is 37 / 63 or more and 85 / 15 or less, and an even more preferable molar ratio is 38 / 62 or more and 80 / 20 or less. ETFE may be a copolymer composed of TFE, ethylene, and a monomer copolymerizable with TFE and ethylene. Examples of the copolymerizable monomer include monomers represented by the following formula CH2=CX 1 Rf 4 , CF2=CFRf 4 , CF2=CFORf 4 , CH2=C(Rf 4 )2 (wherein X 1 is a hydrogen atom or a fluorine atom, and Rf 4 represents a fluoroalkyl group which may contain an ether bond.), and monomers represented by formula (III). Among them, CF2=CFRf 4 , CF2=CFORf 4 and CH2=CX 1 Rf 4 represented fluorine-containing vinyl monomers, monomers represented by formula (III) are preferred, HFP, CF2=CF-ORf 5 (wherein Rf 5 represents a perfluoroalkyl group having 1 to 5 carbon atoms.), perfluoro(alkyl vinyl ether) represented by CF2=CF-CF2-O-Rf 3 (wherein Rf 3 represents a perfluoroalkyl group having 1 to 5 carbon atoms.), perfluoroalkyl allyl ether represented by CF2=CF-CF2-O-Rf 4 and CH2=CX 1 Rf 4 represented fluorine-containing vinyl monomers in which Rf

[0070] is a fluoroalkyl group having 1 to 8 carbon atoms are more preferred. Further, as the monomer copolymerizable with TFE and ethylene, an aliphatic unsaturated carboxylic acid such as itaconic acid and itaconic anhydride may be used. 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.

[0070] The above ETFE preferably has a melting point of 140 to 320 °C, more preferably 160 to 320 °C, and even more preferably 195 to 320 °C.

[0071] The above 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, even more preferably 1.0 g / 10 min or more, and also more preferably 90 g / 10 min or less, even more preferably 80 g / 10 min or less. The MFR of ETFE is a value obtained as the mass (g / 10 min) of the polymer flowing out per 10 minutes 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 using a melt indexer in accordance with ASTM D1238.

[0072] The above low molecular weight PTFE preferably has a melt viscosity (complex viscosity) at 380 °C of 1.0×10 1 ~1.0×10 7 Pa·s. The above melt viscosity is more preferably 1.0×10 2 Pa·s or more, even more preferably 1.5×10 3 Pa·s or more, particularly preferably 7.0×10 3 Pa·s or more, and also more preferably 7.0×10 5 Pa·s or less, even more preferably 3.0×10 5 Pa·s or less, and particularly preferably 1.0×10 5 Pa·s or less. In this specification, "low molecular weight PTFE" means PTFE having the above melt viscosity within the above range.

[0073] The above melt viscosity is a value measured by keeping a 2 g sample pre-heated at 380 °C for 5 minutes at the above temperature under a load of 0.7 MPa using a flow tester (manufactured by Shimadzu Corporation) and a 2φ-8L die in accordance with ASTM D 1238.

[0074] The above low molecular weight PTFE preferably has an MFR value obtained as the mass (g / 10 min) of the polymer flowing out per 10 minutes from a nozzle with an inner diameter of 2.095 mm and a length of 8 mm at 372°C and a load of 5 kg, which is 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 above 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.

[0075] The above low molecular weight PTFE preferably has a melting point of 320 to 340°C. The above melting point is more preferably 324°C or higher, and also 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 especially preferably 330°C or lower.

[0076] The above low molecular weight PTFE may be a homopolymer of TFE, or may be a modified PTFE containing polymerization units based on 99.0 mass% or more of TFE and polymerization units based on 1.0 mass% or less of a modified monomer (hereinafter also referred to as "modified monomer units"). The above modified PTFE may consist only of polymerization units based on TFE and modified monomer units.

[0077] For the above modified PTFE, the content of the modified monomer units is preferably in the range of 0.00001 to 1.0 mass% based on all the polymerization units. As the lower limit of the content of the modified monomer units, 0.0001 mass% is more preferable, 0.001 mass% is even more preferable, 0.005 mass% is even more preferable, and 0.010 mass% is particularly preferable. As the upper limit of the content of the modified monomer units, 0.90 mass% is preferable, 0.50 mass% is more preferable, 0.40 mass% is even more preferable, 0.30 mass% is even more preferable, 0.20 mass% is particularly preferable, and 0.10 mass% is especially preferable.

[0078] Examples of the modified monomer include the monomers described above for PTFE (high molecular weight PTFE) which is a fluororesin that does not exhibit melt fluidity.

[0079] The content of each polymerization unit of the polymer described above can be calculated by appropriately combining NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer.

[0080] The fluororesin B can be produced by known polymerization methods such as emulsion polymerization, suspension polymerization, and solution polymerization.

[0081] The fluororesin composition of the present disclosure may contain particles of fluororesin B. The particles of fluororesin B may be primary particles or secondary particles of fluororesin B.

[0082] When the particles of the fluororesin B 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, still more preferably 300 nm or less. The average primary particle diameter is also preferably 10 nm or more, more preferably 25 nm or more, still more preferably 50 nm or more, even more preferably 100 nm or more, and particularly preferably 150 nm or more. The average primary particle diameter is the average value of the diameters of 100 or more randomly extracted particles observed with a scanning electron microscope (SEM) after dropping an aqueous dispersion adjusted to a solid content concentration of 0.5 mass% onto an aluminum foil and drying and removing water under the conditions of 150°C for 1 hour.

[0083] When the particles of the fluororesin B are secondary particles (powder state), the average secondary particle diameter is preferably 100 μm or less. The above average secondary particle diameter is more preferably 70 μm or less, still more preferably 50 μm or less, and particularly preferably 40 μm or less. The above average secondary particle diameter is preferably 1 μm or more, more preferably 5 μm or more, still more preferably 10 μm or more, and even more preferably 20 μm or more. The above average secondary particle diameter is measured using a laser diffraction particle size distribution measuring device (LS13 320) manufactured by Beckman Coulter, in a dry state, at a vacuum pressure of 20 mH2O, and is assumed to be equal to the particle diameter corresponding to 50% of the cumulative particle size distribution (volume basis).

[0084] The 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 above the melting point. The fluororesin composition of the present disclosure has excellent tensile properties even without containing the fluororesin C, but by further containing the fluororesin C, the tensile properties are further improved. The fluororesin composition of the present disclosure preferably contains the fluororesins A and B, and optionally the fluororesin C.

[0085] The fluororesin C has a portion that has not been heated to a temperature above the melting point. The fluororesin C preferably has one or more melting points in the temperature range of 333 to 360 °C. The above temperature range is more preferably 334 °C or higher, still more preferably 335 °C or higher, and also more preferably 355 °C or lower, still more preferably 350 °C or lower. The fact that the melting point is within the above range indicates that there is a portion that has no history of being heated to a temperature above the melting point. Together with the above melting point, it may also have a melting point in the temperature range below 333 °C.

[0086] When the fluororesin composition of the present disclosure further contains a fluororesin C, it 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 below 333 °C is more preferably below 332 °C, still more preferably below 331 °C, preferably 100 °C or higher, more preferably 140 °C or higher, and still more preferably 160 °C or higher. The temperature range of 333 to 360 °C is more preferably 334 °C or higher, still more preferably 335 °C, and more preferably 355 °C or lower, still more preferably 350 °C or lower. Having melting points in the above two temperature ranges indicates that the fluororesin composition contains a fluororesin A that does not exhibit melt fluidity with a history of heating to a temperature above the melting point and a fluororesin C that has a portion without a history of heating to a temperature above the melting point and does not exhibit melt fluidity.

[0087] The fluororesin C does not exhibit melt fluidity. The melt fluidity is as described above.

[0088] As the fluororesin C, PTFE is preferred. The above PTFE may be high molecular weight PTFE.

[0089] When the above PTFE (high molecular weight PTFE) as the fluororesin C is heated at a rate of 10 °C / min using a differential scanning calorimeter [DSC], at least one endothermic peak appears in the melting heat curve in the range of 333 to 347 °C, and the melting heat quantity in the range of 290 to 350 °C calculated from the above melting heat curve is preferably 62 mJ / mg or more.

[0090] The above PTFE as the fluororesin C preferably has a standard specific gravity (SSG) of 2.130 to 2.280. The above 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. For PTFE without a history of heating to a temperature above its melting point, "high molecular weight" means that the above standard specific gravity is within the above range.

[0091] The above PTFE as fluororesin C usually has non-melt secondary processability. The non-melt secondary processability is as described above.

[0092] The above PTFE as fluororesin C may be a homopolymer of TFE or a modified PTFE containing polymerization units based on 99.0% by mass or more of TFE and polymerization units based on 1.0% by mass or less of a modified monomer (modified monomer units). The above modified PTFE may consist only of polymerization units based on TFE and modified monomer units.

[0093] It is preferable that the content of the modified monomer units in the above modified PTFE is in the range of 0.00001 to 1.0% by mass based on all the polymerization units. As the lower limit of the content of the modified monomer units, 0.0001% by mass is more preferable, 0.001% by mass is still more preferable, 0.005% by mass is still more preferable, 0.010% by mass is particularly more preferable. As the upper limit of the content of the modified monomer units, 0.90% by mass is preferable, 0.50% by mass is more preferable, 0.40% by mass is still more preferable, 0.30% by mass is still more preferable, 0.20% by mass is particularly more preferable, and 0.10% by mass is particularly preferable.

[0094] The modified monomers that can be used in the above PTFE as fluororesin C are the same as those exemplified for PTFE (high molecular weight PTFE) as fluororesin A.

[0095] The fluororesin composition of the present disclosure may contain particles of fluororesin C. The particles of the above fluororesin C may be primary particles of fluororesin C or secondary particles.

[0096] 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. More preferably, the average primary particle diameter is 400 nm or less, still more preferably 350 nm or less, and particularly preferably 300 nm or less. Also, the average primary particle diameter is preferably 10 nm or more, more preferably 25 nm or more, still more preferably 50 nm or more, even more preferably 100 nm or more, and particularly preferably 150 nm or more. The average primary particle diameter is the average value of the diameters of 100 or more randomly extracted particles observed with a scanning electron microscope (SEM) after dropping an aqueous dispersion adjusted to a solid content concentration of 0.5 mass% onto an aluminum foil and drying and removing water under the conditions of 150 °C for 1 hour.

[0097] When the particles of the fluororesin C are secondary particles (in the state of powder), the average secondary particle diameter is preferably 700 μm or less. More preferably, the average secondary particle diameter is 500 μm or less, still more preferably 100 μm or less, even more preferably 60 μm or less, and particularly preferably 50 μm or less. Also, the average secondary particle diameter is preferably 1 μm or more, more preferably 5 μm or more, still more preferably 10 μm or more, and even more preferably 20 μm or more. The average secondary particle diameter is measured dry using a laser diffraction particle size distribution analyzer (LS13 320) manufactured by Beckman Coulter at a vacuum pressure of 20 mH2O and is considered equal to the particle diameter corresponding to 50% of the cumulative particle size distribution (volume basis).

[0098] In one aspect of the fluororesin composition of the present disclosure, when the particles of the fluororesin C are present in the state of primary particles, the average aspect ratio is preferably 2.0 or less, more preferably 1.7 or less, still more preferably 1.6 or less, even more preferably 1.5 or less, particularly preferably 1.4 or less, and most preferably 1.3 or less. Also, the average aspect ratio may be 1.0 or more.

[0099] The above average aspect ratio is determined by observing the fluororesin composition with a scanning electron microscope (SEM), performing image processing on 100 or more primary particles randomly extracted, and calculating the average of the ratio of the major axis to the minor axis.

[0100] In another aspect of the fluororesin composition of the present disclosure, when the particles of the fluororesin C are present in the state of primary particles, the ratio of the particles of the fluororesin C having an aspect ratio of 2.5 or more is preferably 0.5% or more, more preferably 1.0% or more, still more preferably 1.5% or more, and particularly preferably 2.0% or more with respect to the total number of the particles of the fluororesin C. The above ratio is preferably 20% or less, more preferably 15% or less, still more preferably 10% or less.

[0101] The above ratio is determined by observing the fluororesin composition with a scanning electron microscope (SEM), performing image processing on 100 or more primary particles randomly extracted to calculate the aspect ratio of each particle, and calculating the ratio with respect to the total number of the extracted particles.

[0102] The content of the fluororesin A in the fluororesin composition of the present disclosure is preferably 10 to 99.5% by mass with respect to the fluororesin composition in terms of further improving the tensile properties. The above content is more preferably 30% by mass or more, still more preferably 40% by mass or more, particularly preferably 50% by mass or more. Also, it is more preferably 99% by mass or less, still more preferably 95% by mass or less, still more preferably 90% by mass or less, particularly preferably 85% by mass or less, and particularly preferably 80% by mass or less.

[0103] In the fluororesin composition of the present disclosure, the content of fluororesin B is preferably 0.5 to 30% by mass with respect to the above fluororesin composition in terms of further improving the tensile properties. The above content is more preferably 1.0% by mass or more, still 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, still more preferably 20% by mass or less, even more preferably 15% by mass or less, and particularly preferably 10% by mass or less.

[0104] In the fluororesin composition of the present disclosure, the content of fluororesin C is preferably 0 to 80% by mass with respect to the above fluororesin composition in terms of further improving the tensile properties. The above content is more preferably 1% by mass or more, still more preferably 10% by mass or more, even more preferably 20% by mass or more, particularly preferably 30% by mass or more, and more preferably 75% by mass or less, still more preferably 70% by mass or less, even more preferably 65% by mass or less, particularly preferably 60% by mass or less, and particularly preferably 50% by mass or less.

[0105] In the fluororesin composition of the present disclosure, the total amount of fluororesins A to C is preferably 80% by mass or more, more preferably 85% by mass or more, still more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 98% by mass or more with respect to the above fluororesin composition.

[0106] The fluororesin composition of the present disclosure does not exhibit melt fluidity. The MFR of the 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.

[0107] Further, when a preform (unfired molded body) obtained by compression molding the 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 more, it is preferable that the reduction rate of the thickness after heating with respect to the thickness before heating is less than 20%, or the thickness after heating increases compared to the thickness before heating, because this means that the fluororesin composition does not exhibit melt fluidity.

[0108] The fluororesin composition of the present disclosure contains a TFE unit and a modified monomer unit based on a modified monomer copolymerizable with TFE, and it is preferable that the amount of the modified monomer unit is 1.0% by mass or less with respect to all polymerized units. Further, it is preferable that the amount of the TFE unit is 99.0% by mass or more.

[0109] The lower limit of the content of the modified monomer unit in the fluororesin composition of the present disclosure may be 0% by mass, more preferably 0.0001% by mass, still more preferably 0.001% by mass, even more preferably 0.005% by mass, and particularly preferably 0.010% by mass. As the upper limit of the content of the modified monomer unit, 0.90% by mass is preferable, 0.50% by mass is more preferable, 0.40% by mass is still more preferable, 0.30% by mass is even more preferable, 0.20% by mass is particularly more preferable, and 0.10% by mass is particularly preferable.

[0110] The content of the modified monomer unit can be calculated by appropriately combining NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis according to the type of monomer. Further, when the raw material composition is known, it can also be obtained by calculation from the raw material composition.

[0111] The form of the fluororesin composition of the present disclosure is not particularly limited, but it is preferably a powder.

[0112] The fluororesin composition of the present disclosure preferably has an average secondary particle diameter of 5 to 700 μm. The average secondary particle diameter is more preferably 10 μm or more, still more preferably 20 μm or more, and more preferably 600 μm or less, still more preferably 500 μm or less, and particularly preferably 400 μm or less. The average secondary particle diameter is measured dry at a vacuum pressure of 20 mH2O using a laser diffraction particle size distribution analyzer (LS13 320) manufactured by Beckman Coulter, and is assumed to be equal to the particle diameter corresponding to 50% of the cumulative particle size distribution (volume basis).

[0113] In the fluororesin composition of the present disclosure, D90 is preferably 10 μm or more, more preferably 30 μm or more, still more preferably 50 μm or more, and preferably 600 μm or less, more preferably 500 μm or less, still more preferably 400 μm or less. The above D90 is measured dry at a vacuum pressure of 20 mH2O using a laser diffraction particle size distribution analyzer (LS13 320) manufactured by Beckman Coulter, and is assumed to be equal to the particle diameter corresponding to 90% of the cumulative particle size distribution (volume basis).

[0114] In the fluororesin composition of the present disclosure, in terms of further improving the tensile properties, the content (total amount) of the low-molecular-weight fluorine-containing compound is preferably 1 mass ppm or less, more preferably 500 mass ppb or less, still more preferably 100 mass ppb or less, still more preferably 50 mass ppb or less, particularly preferably 25 mass ppb or less, particularly preferably 10 mass ppb or less, particularly more preferably 5 mass ppb or less, particularly preferably 1 mass ppb or less, and most preferably less than 1 mass ppb. The content of the above low-molecular-weight fluorine-containing compound is measured by liquid chromatography-mass spectrometry (LC / MS / MS) after Soxhlet extraction of the sample with methanol.

[0115] Examples of the above low-molecular-weight fluorine-containing compound include fluorine-containing carboxylic acids having 4 or more carbon atoms and their salts, fluorine-containing sulfonic acids having 4 or more carbon atoms and their salts, etc., and any of these may have an ether bond (-O-).

[0116] Examples of the above-mentioned low molecular weight fluorine-containing compound include anionic fluorine-containing surfactants. The anionic fluorine-containing surfactant may be, for example, a surfactant containing fluorine atoms with a total carbon number of 20 or less in the portion excluding the anionic group.

[0117] The above-mentioned anionic fluorine-containing surfactant may also be a surfactant containing fluorine with a molecular weight of the anionic moiety of 800 or less. Note that the above-mentioned "anionic moiety" means the portion excluding the cation of the above-mentioned fluorine-containing surfactant. For example, in the case of F(CF2) n1 COOM represented by the formula (I) described later, it is the portion of "F(CF2) n1 COO".

[0118] Examples of the above-mentioned low molecular weight fluorine-containing compound also include fluorine-containing surfactants with a LogPOW of 3.5 or less. The above-mentioned LogPOW is the partition coefficient between 1-octanol and water, and is represented by LogP [where P represents the ratio of the concentration of the fluorine-containing surfactant in octanol to the concentration of the fluorine-containing surfactant in water when the octanol / water (1:1) mixture containing the fluorine-containing surfactant is phase-separated]. The above-mentioned LogPOW is determined by performing HPLC on standard substances (heptanoic acid, octanoic acid, nonanoic acid, and decanoic acid) having a known octanol / water partition coefficient under the conditions of column; TOSOH ODS-120T column (φ4.6 mm × 250 mm, manufactured by Tosoh Corporation), eluent; acetonitrile / 0.6 mass% HClO4 water = 1 / 1 (vol / vol%), flow rate; 1.0 ml / min, sample volume; 300 μL, column temperature; 40 °C, detection light; UV210 nm, creating a calibration curve between each elution time and the known octanol / water partition coefficient, and calculating from the elution time of HPLC in the sample solution based on this calibration curve.

[0119] Specific examples of the fluorosurfactant include those described in U.S. Patent Application Publication No. 2007 / 0015864, U.S. Patent Application Publication No. 2007 / 0015865, U.S. Patent Application Publication No. 2007 / 0015866, U.S. Patent Application Publication No. 2007 / 0276103, U.S. Patent Application Publication No. 2007 / 0117914, U.S. Patent Application Publication No. 2007 / 142541, U.S. Patent Application Publication No. 2008 / 0015319, U.S. Patent No. 3250808, U.S. Patent No. 3271341, Japanese Patent Application Laid-Open No. 2003-119204, International Publication No. 2005 / 042593, International Publication No. 2008 / 060461, International Publication No. 2007 / 046377, Japanese Patent Application Laid-Open No. 2007-119526, International Publication No. 2007 / 046482, International Publication No. 2007 / 046345, U.S. Patent Application Publication No. 2014 / 0228531, International Publication No. 2013 / 189824, International Publication No. 2013 / 189826, and the like.

[0120] Examples of the anionic fluorosurfactant include those 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. Rf n0 is an alkylene group having 3 to 20 carbon atoms, which is linear, branched, or cyclic, and in which some or all of the H atoms are substituted by F atoms. The alkylene group may contain one or more ether bonds, and some of the H atoms may be substituted by Cl atoms. Y 0 is an anionic group.) Compounds represented by this formula are included.

[0121] Y 0 The anionic group of may be -COOM, -SO2M, or -SO3M, and may be -COOM or -SO3M. M is H, a metal atom, NR 74. It may be an imidazolium optionally having a substituent, a pyridinium optionally having a substituent, or a phosphonium optionally having a substituent, and R 7 is H or an organic group. Examples of the above metal atom include an alkali metal (Group 1), an alkaline earth metal (Group 2), etc., and for example, it is Na, K or Li. R 7 may be H or an organic group of C 1-10 may be H or an organic group of C 1-4 may be H or an organic group of C 1-4 and may be an alkyl group of C. M may be H, a metal atom or NR 7 4, may be H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or NR 7 4, and may be H, Na, K, Li or NH4.

[0122] The above Rf n0 may be one in which 50% or more of H is substituted with fluorine.

[0123] Examples of the compound represented by the above general formula (N 0 ) include the following general formula (N 1 ): X n0 -(CF2) m1 -Y 0 (N 1 ) (In the formula, X n0 is H, Cl and 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, 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 that may contain an ether bond and / or a chlorine atom having 1 to 13 carbon atoms, m3 is an integer of 1 to 3, 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 that may contain an ether bond having 1 to 12 carbon atoms, 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. A compound represented by the general formula (N 5 ): [Chemical formula] (In the formula, X n2 , X n3 and X n4 may be the same or different and are H, F, or a linear or branched partially or fully fluorinated alkyl group that may contain an ether bond having 1 to 6 carbon atoms. Rf n5 is a linear or branched partially or fully fluorinated alkylene group that may contain an ether bond having 1 to 3 carbon atoms, L is a linking group, and Y 0 is as defined above. However, X n2, X n3 , X n4 and Rf n5 The total carbon number of is 18 or less. Examples thereof include compounds represented by

[0124] More specifically, as the compound represented by the above general formula (N 0 ), there are, for example, perfluorocarboxylic acid (I) represented by the following general formula (I), ω-H perfluorocarboxylic acid (II) represented by the following general formula (II), perfluoroether carboxylic acid (III) represented by the following general formula (III), perfluoroalkyl alkylene carboxylic acid (IV) represented by the following general formula (IV), alkoxyfluorocarboxylic acid (V) represented by the following general formula (V), perfluoroalkyl sulfonic acid (VI) represented by the following general formula (VI), ω-H perfluorosulfonic acid (VII) represented by the following general formula (VII), perfluoroalkyl alkylene sulfonic acid (VIII) represented by the following general formula (VIII), alkyl alkylene carboxylic acid (IX) represented by the following general formula (IX), fluorocarboxylic acid (X) represented by the following general formula (X), alkoxyfluorosulfonic acid (XI) represented by the following general formula (XI), compound (XII) represented by the following general formula (XII), compound (XIII) represented by the following general formula (XIII), and the like.

[0125] The above perfluorocarboxylic acid (I) is represented by the following general formula (I): F(CF2) n1 COOM (I) (In the formula, n1 is an integer of 3 to 14, and M is H, a metal atom, NR 7 4, an optionally substituted imidazolium, an optionally substituted pyridinium or an optionally substituted phosphonium, and R 7 is H or an organic group.)

[0126] The above 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.) is represented by the following formula.

[0127] The above perfluoroether carboxylic acid (III) is represented by the following general formula (III): Rf 1 -O-(CF(CF3)CF2O) n3 CF(CF3)COOM (III) (wherein 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.) is represented by the following formula.

[0128] The above perfluoroalkyl alkylene carboxylic acid (IV) is represented by the following general formula (IV): Rf 2 (CH2) n4 Rf 3 COOM (IV) (wherein Rf 2 is a perfluoroalkyl group having 1 to 5 carbon atoms, 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.) is represented by the following formula.

[0129] The above alkoxyfluorocarboxylic acid (V) is represented by the following general formula (V): Rf 4 -O-CY 1 Y 2 CF2-COOM (V) (wherein Rf 4 is a linear or branched partially or fully fluorinated alkyl group which may contain an ether bond and / or a chlorine atom having 1 to 12 carbon atoms, Y 1 and Y 2 are the same or different and are H or F, and M is as defined above.) is represented by the following formula.

[0130] The above perfluoroalkyl sulfonic 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.)

[0131] The above 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.)

[0132] The above perfluoroalkylalkylene sulfonic acid (VIII) is represented by the following general formula (VIII): Rf 5 (CH2) n7 SO3M (VIII) (wherein 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.)

[0133] The above alkylalkylene carboxylic acid (IX) is represented by the following general formula (IX): Rf 6 (CH2) n8 COOM (IX) (wherein Rf 6 is a linear or branched or fully fluorinated alkyl group which may contain an ether bond having 1 to 13 carbon atoms, n8 is an integer of 1 to 3, and M is as defined above.)

[0134] The above fluorocarboxylic acid (X) is represented by the following general formula (X): Rf 7 -O-Rf 8 -O-CF2-COOM (X) (wherein Rf 7 is a linear or branched or fully fluorinated alkyl group which may contain an ether bond and / or a chlorine atom having 1 to 6 carbon atoms, Rf 8is a linear or branched, partial or fully fluorinated alkyl group having 1 to 6 carbon atoms, and M is as defined above.) represented by.)

[0135] The above alkoxyfluorosulfonic acid (XI) has 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, partial or fully fluorinated alkyl group which may contain an ether bond having 1 to 12 carbon atoms and may contain chlorine, Y 1 and Y 2 are the same or different and are H or F, and M is as defined above.) represented by.)

[0136] The above compound (XII) has the following general formula (XII):

Chemical formula

[0137] The above compound (XIII) has the following general formula (XIII): Rf 11 -O-(CF2CF(CF3)O)n9 (CF2O) n10 CF2COOM (XIII) (wherein, Rf 11 is a fluoroalkyl group having 1 to 5 carbon atoms and containing chlorine, n9 is an integer of 0 to 3, n10 is an integer of 0 to 3, and M is as defined above.) It is represented by. As the compound (XIII), CF2ClO(CF2CF(CF3)O) n9 (CF2O) n10 CF2COONH4 (a mixture with an average molecular weight of 750, wherein n9 and n10 are as defined above.) may be mentioned.

[0138] As described above, examples of the anionic fluorine-containing surfactant include carboxylic acid surfactants, sulfonic acid surfactants, and the like.

[0139] The fluorine-containing surfactant may be a single fluorine-containing surfactant or a mixture containing two or more fluorine-containing surfactants.

[0140] 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,

Chemical formula

[0141] The fluororesin composition of the present disclosure may further contain a filler. Examples of the filler include 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, bronzes, gold, silver, copper, and nickel. Among them, at least one selected from the group consisting of glass fiber, carbon fiber, carbon black, and bronzes is preferable.

[0142] The content of the filler may be, for example, 0 to 80% by mass based on the fluororesin composition.

[0143] The fluororesin composition of the present disclosure can be produced, for example, by mixing the powder of fluororesin A, the particles of fluororesin B, and, if necessary, the particles of fluororesin C.

[0144] The particles of the fluororesin B may be mixed with the powder of the fluororesin A in the form of a powder or in the form of an aqueous dispersion. However, in terms of producing a fluororesin composition having more excellent tensile properties, it is preferable to mix the powder of the fluororesin A in the form of an aqueous dispersion.

[0145] The aqueous dispersion containing the particles of the fluororesin B can be produced by a known method. For example, it can be produced by carrying out emulsion polymerization of the monomers necessary to constitute the fluororesin B in an aqueous medium in the presence of an anionic surfactant and a polymerization initiator. In the above emulsion polymerization, a chain transfer agent, a buffer, a pH adjuster, a stabilization aid, a dispersion stabilizer, etc. may be used as necessary. Those skilled in the art can control the composition, physical properties of the fluororesin B, physical properties of the particles, etc. by adjusting the conditions of the above emulsion polymerization.

[0146] The above aqueous dispersion may contain a hydrocarbon-based surfactant. The hydrocarbon-based surfactant preferably does not contain a fluorine atom. The hydrocarbon-based surfactant may be the one used in the above emulsion polymerization or the one added after the above emulsion polymerization.

[0147] As the above hydrocarbon-based surfactant, for example, those described in JP-T-2013-542308, JP-T-2013-542309, JP-T-2013-542310, etc. can be used.

[0148] The hydrocarbon-based surfactant has a hydrophilic part and a hydrophobic part on the same molecule. These may be cationic, nonionic or anionic.

[0149] The cationic surfactant usually has a positively charged hydrophilic part such as alkylated ammonium bromide and other alkylated ammonium halides, and a hydrophobic part such as long-chain fatty acids.

[0150] The anionic surfactant usually has a hydrophilic part such as carboxylate, sulfonate or sulfate, and a hydrophobic part which is a long-chain hydrocarbon part such as alkyl.

[0151] Nonionic surfactants usually do not contain charged groups and have a hydrophobic part that is a long-chain hydrocarbon. The hydrophilic part of nonionic surfactants contains water-soluble functional groups such as chains of ethylene ethers derived from polymerization with ethylene oxide.

[0152] The hydrocarbon-based surfactant is preferably an anionic surfactant or a nonionic surfactant.

[0153] Examples of anionic hydrocarbon-based surfactants include Versatic® 10 from Resolution Performance Products, the Avanel S series (S-70, S-74, etc.) manufactured by BASF, and the like.

[0154] Examples of anionic hydrocarbon-based surfactants also include R-L-M 1 (wherein 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 number of carbon atoms is 3 or more, it may contain a monovalent or divalent heterocyclic ring or may be ringed. L is -ArSO3 - , -SO3 - , -SO4-, -PO3 - or -COO - and M 1 is H, a metal atom, NR 5 4 (R 5 may be the same or different and is H or an organic group having 1 to 10 carbon atoms), an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. -ArSO3 - is an aryl sulfonate. ) Also included are anionic surfactants represented by. Specifically, CH3-(CH2) n -L-M 1 (wherein n is an integer of 6 to 17. L and M 1 are the same as above) are included. R is an alkyl group having 12 to 16 carbon atoms, and a mixture in which L is a sulfate or sodium dodecyl sulfate (SDS) can also be used.

[0155] As the anionic hydrocarbon surfactant, R 6 (-L-M 1 )2 (wherein R 6 is a linear or branched alkylene group having 1 or more carbon atoms which may have a substituent, or a cyclic alkylene group having 3 or more carbon atoms which may have a substituent. When the number of carbon atoms is 3 or more, it may contain a monovalent or divalent heterocyclic ring or may be ringed. L is -ArSO3 - , -SO3 - , -SO4-, -PO3 - or -COO - and M 1 is H, a metal atom, NR 5 4 (R 5 may be the same or different and is H or an organic group having 1 to 10 carbon atoms), an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. -ArSO3 - is an aryl sulfonate.) The anionic surfactant represented by) is also mentioned.

[0156] As the anionic hydrocarbon surfactant, R 7 (-L-M 1 )3 (wherein R 7 is a linear or branched alkylidine group having 1 or more carbon atoms which may have a substituent, or a cyclic alkylidine group having 3 or more carbon atoms which may have a substituent. When the number of carbon atoms is 3 or more, it may contain a monovalent or divalent heterocyclic ring or may be ringed. L is -ArSO3 - , -SO3 - , -SO4-, -PO3 - or -COO - and M 1 is H, a metal atom, NR 5 4 (R 5may be the same or different, and is H or an organic group having 1 to 10 carbon atoms), an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. -ArSO3 - is an aryl sulfonate. ) The anionic surfactant represented by is also included.

[0157] Examples of the anionic hydrocarbon surfactant also include the sulfosuccinate surfactant Lankropol (registered trademark) K8300 of Akzo Nobel Surface Chemistry LLC. Examples of the sulfosuccinate hydrocarbon surfactant include sodium diisodecyl sulfosuccinate, (Emulsogen (registered trademark) SB10 of Clariant), sodium diisotridecyl sulfosuccinate (Polirol (registered trademark) TR / LNA of Cesapinia Chemicals), etc.

[0158] Examples of the anionic hydrocarbon surfactant also include the PolyFox (registered trademark) surfactant of Omnova Solutions, Inc. (PolyFox TM PF-156A, PolyFox TM PF-136A, etc.).

[0159] Examples of the nonionic surfactant include ether-type nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and polyoxyethylene alkylene alkyl ether; polyoxyethylene derivatives such as ethylene oxide / propylene oxide block copolymers; ester-type nonionic surfactants such as polyoxyethylene fatty acid ester (polyoxyethylene alkyl ester), sorbitan fatty acid ester (sorbitan alkyl ester), polyoxyethylene sorbitan fatty acid ester (polyoxyethylene sorbitan alkyl ester), polyoxyethylene sorbitol fatty acid ester, and glycerin fatty acid ester (glycerol ester); amine-based nonionic surfactants such as polyoxyethylene alkylamine and alkyl alkanolamide; and derivatives thereof. One of these can be used alone, or two or more of them can be used in combination. The nonionic surfactant may be a non-fluorinated nonionic surfactant.

[0160] Examples of the polyoxyethylene alkyl ether include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, and polyoxyethylene behenyl ether.

[0161] Examples of the polyoxyethylene alkyl phenyl ether include polyoxyethylene nonyl phenyl ether and polyoxyethylene octyl phenyl ether.

[0162] Specific examples of the polyoxyethylene fatty acid ester include polyethylene glycol monolaurate, polyethylene glycol monooleate, and polyethylene glycol monostearate.

[0163] Examples of the sorbitan fatty acid ester include sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, and sorbitan monooleate.

[0164] Examples of the polyoxyethylene sorbitan fatty acid ester include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, and the like.

[0165] Examples of the glycerin fatty acid ester include glycerol monomyristate, glycerol monostearate, glycerol monooleate, and the like.

[0166] Examples of the derivative include polyoxyethylene alkylamine, polyoxyethylene alkylphenyl-formaldehyde condensate, polyoxyethylene alkyl ether phosphate, and the like.

[0167] The ether-type nonionic surfactant and the ester-type nonionic surfactant may have an HLB value of 10 to 18.

[0168] Examples of the nonionic hydrocarbon-based surfactant include 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.), Tergitol (registered trademark) L series manufactured by Dow Chemical Company; Pluronic (registered trademark) R series (31R1, 17R2, 10R5, 25R4 (m~22, n~23)), T-Det series (A138), Iconol (registered trademark) TDA series (TDA-6, TDA-9, TDA-10) manufactured by BASF, and the like.

[0169] 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 preferably a compound having no alkylphenol group in the structure, such as a compound having no benzene ring.

[0170] Among the above 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. As the above polyoxyethylene alkyl ether, those having a polyoxyethylene alkyl ether structure having an alkyl group with 10 to 20 carbon atoms are preferred, and those having a polyoxyethylene alkyl ether structure having an alkyl group with 10 to 15 carbon atoms are more preferred. The alkyl group in the above polyoxyethylene alkyl ether structure preferably has a branched structure.

[0171] The content of the above hydrocarbon-based surfactant is preferably 12% by mass or less, more preferably 8% by mass or less, still 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, in terms of being able to produce a fluororesin composition with even less coloring and even better tensile properties with respect to the solid content of the above aqueous dispersion. The content of the above hydrocarbon-based surfactant may also be 1 mass ppm or more, may be 10 mass ppm or more, may be 100 mass ppm or more, or may be 500 mass ppm or more.

[0172] The aqueous dispersion obtained by the above emulsion polymerization, or the aqueous dispersion containing the above hydrocarbon-based surfactant, may be contacted with an anion exchange resin or a mixed bed containing an anion exchange resin and a cation exchange resin, may be concentrated, or may be treated by both of these. By performing the above treatment, low molecular weight fluorine-containing compounds can be removed. As the above treatment, known treatments can be adopted.

[0173] A mixture obtained by mixing a powder of fluororesin A and an aqueous dispersion containing particles of fluororesin B may be coagulated. Examples of the coagulation method include a method of aggregating emulsion particles by freezing or mechanical shearing force. Stirring may be carried out while adding a water-soluble organic compound such as methanol or acetone, an inorganic salt such as potassium nitrate or ammonium carbonate, or an inorganic acid such as hydrochloric acid, sulfuric acid, or nitric acid as a coagulant. The above coagulation may also be carried out continuously using an in-line mixer or the like.

[0174] A fluororesin composition is obtained by drying the above mixture. The wet powder obtained by the above coagulation may be dried. The drying method is not particularly limited, and known methods can be used. For example, it can be carried out using means such as vacuum, high frequency, or hot air. The drying temperature is preferably 50°C or higher, more preferably 70°C or higher, still more preferably 100°C or higher, particularly preferably 150°C or higher, and preferably 300°C or lower, more preferably 250°C or lower.

[0175] The particles of the above fluororesin C may be mixed with the powder of fluororesin A (and the particles of fluororesin B) in the form of a powder, or may be mixed with the powder of fluororesin A (and the particles of fluororesin B) in the form of an aqueous dispersion.

[0176] The obtained fluororesin composition may be pulverized. The above pulverization may be carried out by a known method. For example, it can be carried out using a pulverizer such as an air jet mill, a hammer mill, a force mill, a mortar-type pulverizer, or a freeze pulverizer.

[0177] The obtained fluororesin composition may be granulated. Thereby, a fluororesin composition having a high bulk density and excellent handleability is obtained. Examples of the above granulation method include known methods such as an underwater granulation method, a warm water granulation method, an emulsifying dispersion granulation method, an emulsifying warm water granulation method, a solvent-free granulation method, and a dry solvent granulation method.

[0178] The fluororesin composition of the present disclosure preferably has a tensile breaking strength of 10 MPa or more, more preferably 13 MPa or more, still more preferably 15 MPa or more, even more preferably 17 MPa or more, particularly preferably 20 MPa or more. The upper limit is not particularly limited and may be, for example, 30 MPa. The above tensile breaking strength is measured in accordance with ASTM D1708 using a dumbbell prepared by punching out a molded body fired by a process of charging 35 g of the above fluororesin composition into a mold of φ100 mm, compression molding under the conditions of a pressure of 30 MPa for 1 minute, heating from room temperature to 300 °C in 3 hours, then heating from 300 °C to 370 °C in 4 hours, holding at 370 °C for 12 hours, then cooling to 300 °C in 5 hours, and then cooling to room temperature in 1 hour.

[0179] The fluororesin composition of the present disclosure preferably has a tensile breaking strain of 150% or more, more preferably 200% or more, still more preferably 250% or more, even more preferably 300% or more, particularly preferably 360% or more, and especially preferably 400% or more. The upper limit is not particularly limited and may be, for example, 600%. The above tensile breaking strain is measured in accordance with ASTM D1708 using a dumbbell prepared by punching out a molded body fired by a process of charging 35 g of the above fluororesin composition into a mold of φ100 mm, compression molding under the conditions of a pressure of 30 MPa for 1 minute, heating from room temperature to 300 °C in 3 hours, then heating from 300 °C to 370 °C in 4 hours, holding at 370 °C for 12 hours, then cooling to 300 °C in 5 hours, and then cooling to room temperature in 1 hour.

[0180] The fluororesin composition of the present disclosure can be suitably used as a molding material. The method for molding the above fluororesin composition is not particularly limited, and examples thereof include compression molding, ram extrusion molding, and isostatic molding. Among them, compression molding is preferred. The fluororesin composition of the present disclosure is preferably a powder for compression molding.

[0181] The present disclosure also provides a molded article obtained by compression molding and firing the fluororesin composition of the present disclosure. Despite containing a fluororesin having a history of being heated to a temperature equal to or higher than the melting point, the molded article of the present disclosure is excellent in tensile properties.

[0182] The above compression molding can be performed, for example, by maintaining a pressure of 10 to 50 MPa for 1 minute to 30 hours.

[0183] The above firing can be performed, for example, by heating at a temperature of 350 to 380 °C for 0.5 to 50 hours.

[0184] The molded article of the present disclosure preferably has a tensile breaking strength of 10 MPa or more, more preferably 13 MPa or more, still more preferably 15 MPa or more, even more preferably 17 MPa or more, and particularly preferably 20 MPa or more. The upper limit is not particularly limited, but may be, for example, 30 MPa. The above tensile breaking strength is measured in accordance with ASTM D1708.

[0185] The molded article of the present disclosure preferably has a tensile breaking strain of 150% or more, more preferably 200% or more, still more preferably 250% or more, even more preferably 300% or more, particularly preferably 360% or more, and especially preferably 400% or more. The upper limit is not particularly limited, but may be, for example, 600%. The above tensile breaking strain is measured in accordance with ASTM D1708.

[0186] The molded article obtained from the fluororesin composition of the present disclosure can be suitably used for lining sheets, packings, gaskets, diaphragm valves, heat-resistant electric wires, heat-resistant insulating tapes such as those for vehicle motors and generators, release sheets, sealing materials, casings, sleeves, bellows, hoses, piston rings, butterfly valves, square grooves, wafer carriers, and the like.

[0187] Although the embodiments have been described above, it will be understood that various changes in form and detail can be made without departing from the spirit and scope of the claims.

Example

[0188] Next, the present disclosure will be described in more detail with reference to examples, but the present disclosure is not limited to these examples only.

[0189] Various physical properties were measured by the following methods.

[0190] (Melting point) Using X-DSC7000 (manufactured by Hitachi High-Tech Science Corporation), it was determined as the temperature corresponding to the minimum point in the melting heat curve obtained by performing differential scanning calorimetry [DSC] at a heating rate of 10 °C / min. When there are two or more minimum points in one melting peak, each was taken as the melting point. When the fluororesin B is 5% by mass or less, using X-DSC7000 (manufactured by Hitachi High-Tech Science Corporation), the temperature was raised to 300 °C, which is lower than the melting point of the fluororesin B, at a heating rate of 10 °C / min, held at 300 °C for 10 minutes, and then the temperature was raised at a heating rate of 10 °C / min to perform differential scanning calorimetry [DSC]. It was determined as the temperature corresponding to the minimum point in the obtained melting heat curve.

[0191] (Monomer composition of fluororesin) 19 Measured by the F-NMR method.

[0192] (Monomer composition of fluororesin composition) Determined by calculation from the raw material composition.

[0193] (Secondary particle diameter of powder) Using a laser diffraction particle size distribution measuring device (LS13 320) manufactured by Beckman Coulter, the measurement was performed dry at a vacuum pressure of 20 mH2O, and it was determined based on the obtained particle size distribution (volume basis). The average secondary particle diameter was assumed to be equal to the particle diameter corresponding to 50% of the cumulative particle size distribution. The particle diameter corresponding to 10% was designated as D10, and the particle diameter corresponding to 90% was designated as D90.

[0194] (Average primary particle diameter) An aqueous dispersion with a solid content concentration adjusted to 0.5% by mass was dropped onto an aluminum foil, and water was dried and removed under the conditions of 150 °C for 1 hour. It was observed with a scanning electron microscope (SEM), and the average value of the diameters of 100 or more randomly extracted particles was determined.

[0195] (Aspect ratio) The fluororesin aqueous dispersion diluted so that the solid content concentration was 0.5% by mass was observed with a scanning electron microscope (SEM). Image processing was performed on 100 or more randomly extracted particles, and the average aspect ratio was determined from the average of the ratio of the major axis to the minor axis. The ratio of particles with an aspect ratio of 2.5 or more was obtained by observing the fluororesin aqueous dispersion diluted so that the solid content concentration was 0.5% by mass with a scanning electron microscope (SEM), performing image processing on 100 or more randomly extracted particles to calculate the aspect ratio of each particle, and determining it as the ratio to the total number of the above-extracted particles.

[0196] (Solid content concentration of the aqueous dispersion) The solid content concentration (P% by mass) in the aqueous dispersion was calculated from the formula: P = [Z / X] × 100 (mass%), where about 1 g (X g) of the sample was placed in an aluminum cup with a diameter of 5 cm, heated at 110 °C for 30 minutes to obtain a heating residue (Y g), and further, the obtained heating residue (Y g) was heated at 300 °C for 30 minutes to obtain a heating residue (Z g).

[0197] (Content of nonionic surfactant in the aqueous dispersion) The content (N% by mass) of the nonionic surfactant in the aqueous dispersion with respect to PTFE was calculated from the formula: N = [(Y - Z) / Z] × 100 (mass%), where about 1 g (X g) of the sample was placed in an aluminum cup with a diameter of 5 cm, heated at 110 °C for 30 minutes to obtain a heating residue (Y g), and further, the obtained heating residue (Y g) was heated at 300 °C for 30 minutes to obtain a heating residue (Z g).

[0198] (Apparent density) Measured in accordance with JIS K 6891.

[0199] (Standard Specific Gravity (SSG)) Using samples molded in accordance with ASTM D4895 89, measurement was carried out by the water displacement method in accordance with ASTM D 792.

[0200] (MFR) In accordance with ASTM D1238, using a melt indexer, at a measurement temperature determined according to the type of fluororesin (for example, 372 °C for PFA and FEP, 297 °C for ETFE), a load (for example, 5 kg for PFA, FEP and ETFE), the mass of the polymer flowing out per 10 minutes (g / 10 min) from a nozzle with an inner diameter of 2.095 mm and a length of 8 mm was measured.

[0201] (Tensile test) 35 g of powder was put into a mold with a diameter of φ100 mm, and after compression molding at 30 MPa for 1 minute, the temperature was raised from room temperature to 300 °C in 3 hours, then from 300 °C to 370 °C in 4 hours, held at 370 °C for 12 hours, then cooled to 300 °C in 5 hours, and then cooled to room temperature in 1 hour. The molded product was obtained by firing, and dumbbells were prepared by punching out this molded product. A tensile test was carried out in accordance with ASTM D 1708, and the tensile breaking strength and tensile breaking strain were measured.

[0202] (Melt fluidity of fluororesin composition) When the fluororesin composition (powder) was compression molded and fired under the same conditions as the above tensile test, when the thickness after firing decreased by 20% or more with respect to the thickness before firing, it was determined that the fluororesin composition had melt fluidity. When the reduction rate before and after firing was less than 20%, or when the thickness after firing increased compared to the thickness before firing, it was determined that there was no melt fluidity.

[0203] (Content of low molecular weight fluorine-containing compound) Weighed 1 g of the fluororesin composition (powder), added 10 mL of a 0.3% ammonium hydroxide methanol solution (A) prepared with aqueous ammonia and methanol, set the sample bottle in an ultrasonic cleaner adjusted to 60 °C, and performed ultrasonic treatment for 2 hours to obtain an extract. For the fluorine-containing compounds in the extract, measurement was carried out using a liquid chromatograph mass spectrometer (Agilent 1290 Infinity II type LC, 6530 type time-of-flight mass spectrometer). The measurement device configuration and measurement conditions are shown in Table 1. Compounds that could be identified as fluorine-containing compounds with a molecular weight of 800 or less from the exact mass were peak-extracted, and an extracted chromatogram was drawn. Using an aqueous solution of perfluorooctanoic acid with a known concentration, aqueous solutions with four levels of content were prepared, and each aqueous solution with a different content was analyzed. The relationship between the content and the area of the corresponding area was plotted to draw a calibration curve. Using the above calibration curve, the content of the fluorine-containing compounds with a molecular weight of 800 or less in the extract was calculated in terms of perfluorooctanoic acid using the above extracted chromatogram and calibration curve.

[0204]

Table 1

[0205] Synthesis Example 1 (Synthesis of ammonium perfluoroether carboxylate A) After purging 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, and then 100 g of hexafluoropropylene oxide was introduced and stirred. Thereafter, 38.5 g of carbonyl fluoride and 100 g of hexafluoropropylene oxide were additionally charged. Thereafter, the same amounts of carbonyl fluoride and hexafluoropropylene oxide were further charged. After completion of the reaction, the reaction mixture was taken out and separated to obtain the lower layer reaction product.

[0206] 1000 mL of tetraglyme and 75 g of CsF were placed in a 6 L autoclave, and the inside of the autoclave was replaced with nitrogen. Then, the autoclave was cooled, 2100 g of the reaction product obtained above was charged, and hexafluoropropylene oxide was introduced into the autoclave to start the reaction. Finally, 1510 g of hexafluoropropylene oxide was charged. Then, the contents were taken out and separated into an upper layer and a lower layer using a separatory funnel. The upper layer was 1320 g and the lower layer was 3290 g. The lower layer was rectified and isolated.

[0207] Next, 1000 g of pure water was added to 1000 g of the isolated target product for hydrolysis. Then, it was separated using a separatory funnel to recover the organic layer (lower layer). The recovered solution was washed with sulfuric acid water. Furthermore, the obtained solution was purified by simple distillation. After purification, 500 g of the simple distillate obtained above was added dropwise to an aqueous solution obtained by mixing the obtained compound, 76 g of a 28% by mass aqueous ammonia solution, and 600 g of pure water. After the addition dropwise was completed, a 28% by mass aqueous ammonia solution was added to adjust the pH to 7. This was freeze-dried to obtain ammonium perfluoroether carboxylate A.

[0208] Production Example 1 (Preparation of Fluororesin Powder A-1) Using 35 g of PTFE molding powder (standard specific gravity (SSG): 2.159, melting point: 345.0 °C) obtained by pulverizing the crude powder of homopolymer PTFE obtained by suspension polymerization of only TFE monomer with a pulverizer, compression molding was performed at 30 MPa for 1 minute using a mold with a diameter of 100 mm, and a molded product was obtained by baking at 370 °C for 3 hours. After cutting the obtained molded product, it was pulverized with a pulverizer to obtain fluororesin powder A-1. The melting point of fluororesin powder A-1 was 328 °C, the average secondary particle diameter was 23 μm, D10 was 8 μm, D90 was 48 μm, and the apparent density was 0.64 g / ml.

[0209] Production Example 2 (Preparation of Fluororesin Powder A-2) The molded product obtained in the same manner as in Production Example 1 was cut and then pulverized with a pulverizer to obtain fluororesin powder A-2. The melting point of the fluororesin powder A-2 was 328°C, the average secondary particle diameter was 37 μm, D10 was 7 μm, D90 was 87 μm, and the apparent density was 0.53 g / ml.

[0210] Production Example 3 (Preparation of PFA aqueous dispersion B-1 containing PFA particles) In a 6 L SUS autoclave equipped with a stirring blade, using ammonium perfluoroether carboxylate A, a PFA aqueous dispersion B-1 containing PFA particles composed of TFE units and perfluoro(propyl vinyl ether) (PPVE) units was obtained by a known emulsion polymerization method. The solid content concentration of the obtained PFA aqueous dispersion B-1 was 14% by mass, the average primary particle diameter was 291 nm, MFR was 22 g / 10 min, the melting point was 314°C, and the content of PPVE units was 1.4 mol%.

[0211] Production Example 4 (Preparation of PFA powder B-2) In a 6 L SUS autoclave equipped with a stirring blade, using ammonium perfluoroether carboxylate A, 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. The obtained PFA aqueous dispersion was coagulated to obtain PFA powder B-2. The average secondary particle diameter of the PFA powder B-2 was 11 μm, MFR was 27 g / 10 min, the melting point was 298°C, and the content of PPVE units was 2.1 mol%.

[0212] Production Example 5 (Preparation of PFA powder B-3) The PFA aqueous dispersion obtained in the same manner as in Production Example 3 was coagulated to obtain PFA powder B-3. The average secondary particle diameter of the PFA powder B-3 was 1.5 μm, MFR was 28 g / 10 min, the melting point was 314°C, and the content of PPVE units was 1.4 mol%.

[0213] Production Example 6 (Preparation of FEP powder B-4) In a 6 L SUS autoclave equipped with a stirring blade, using ammonium persulfate, an FEP aqueous dispersion containing FEP particles composed of TFE units, hexafluoropropylene [HFP] units, and perfluoro(propyl vinyl ether) units was obtained by a known emulsion polymerization method. The obtained FEP aqueous dispersion was coagulated with nitric acid, dehydrated by pressing, and dried at 170 °C for 4 hours to obtain FEP powder B-4. The average secondary particle diameter of the obtained FEP powder was 19 μm, the MFR was 24 g / 10 min, the melting point was 261 °C, and the total content of HFP units and PPVE units was 7.6 mol%.

[0214] Production Example 7 (Production of FEP Powder B-5) Using the method described in Example 1 of International Publication No. 2001 / 036504, (by adjusting the charged amounts of TFE monomer, HFP monomer, di-(ω-hydrodecafluoroheptanoyl) peroxide (DHP), and methanol), FEP powder B-5 composed of TFE units and hexafluoropropylene [HFP] units was obtained. The average secondary particle diameter of the obtained FEP powder was 50 μm, the MFR was 1 g / 10 min, the melting point was 302 °C, and the total content of FEP units and PPVE units was 8.4 mol%.

[0215] Production Example 8 (Production of Fluororesin Aqueous Dispersion C-1) In a 6 L SUS autoclave equipped with a stirring blade, using ammonium perfluoroether carboxylate A, a fluororesin aqueous dispersion C-a containing homopolymer PTFE particles composed only of TFE monomer was obtained by a known emulsion polymerization method.

[0216] Nonionic surfactant TDS-80 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) was added to the fluororesin aqueous dispersion C-a to prepare a dispersion with a nonionic surfactant concentration of 10 parts by mass based on 100 parts by mass of PTFE. Subsequently, a column with a diameter of 20 mm was filled with 250 mL of an OH-type anion exchange resin (trade name Amberjet AMJ4002, manufactured by Rohm and Haas), and the above dispersion was passed through at an SV of 1. Furthermore, nonionic surfactant TDS-80 was added to the obtained aqueous dispersion so that the amount became 16 parts by mass based on 100 parts by mass of PTFE, and it was held at 65 °C for 3 hours and separated into a supernatant phase and a concentrated phase. The concentrated phase was recovered to obtain a fluororesin aqueous dispersion C-b.

[0217] To the fluororesin aqueous dispersion C-b, nonionic surfactant TDS-80 was added so that the amount became 6.0% by mass based on PTFE, and further deionized water and aqueous ammonia were added to obtain a fluororesin aqueous dispersion C-1. The solid content concentration was 60.2% by mass, and the content of the nonionic surfactant was 6.0% by mass based on PTFE.

[0218] Production Example 9 (Production of Fluororesin Powder C-2) The crude powder of homopolymer PTFE obtained by suspension polymerization of only TFE monomer was pulverized with a pulverizer to obtain fluororesin powder C-2. The apparent density of the fluororesin powder C-2 was 0.34 g / ml, the average secondary particle diameter was 24 μm, D90 was 55 μm, the standard specific gravity (SSG) was 2.163, and the melting point was 345.0 °C.

[0219] Production Example 10 (Production of Fluororesin Powder C-3) The crude powder of modified PTFE obtained by suspension polymerization of TFE and perfluoropropyl vinyl ether (PPVE) was pulverized with a pulverizer to obtain fluororesin powder C-3. The apparent density of the fluororesin powder C-3 was 0.33 g / ml, the average secondary particle diameter was 28 μm, D90 was 77 μm, the standard specific gravity (SSG) was 2.168, the melting point was 341.5 °C, and the amount of PPVE units was 0.09% by mass.

[0220] Example 1 After shaking 95 g of fluororesin powder A-1 and 36 g of PFA aqueous dispersion B-1 in a flask, methanol was added for precipitation, followed by filtration and washing with water and methanol to obtain a wet powder. The obtained wet powder was dried in an electric furnace at 150 °C for 15 hours to remove water. The dried powder was pulverized for 60 seconds at a rotational speed of 2900 rpm using a Wonder Crusher WC-3 to obtain a mixed powder (fluororesin composition). The above mixed powder contained 99.82% by mass of TFE units and 0.18% by mass of PPVE units based on all polymerization units. The melting points of the above mixed powder were 314 °C and 329 °C, the tensile breaking strength was 12 MPa, the tensile breaking strain was 253%, the average secondary particle diameter was 25 μm, D10 was 9 μm, and D90 was 51 μm. Since the thickness of the molded product increased before and after firing and the shape was maintained, it was determined that the above mixed powder did not exhibit melt fluidity.

[0221] Example 2 A mixed powder was obtained in the same manner as in Example 1 except that 90 g of fluororesin powder A-1 and 71 g of PFA aqueous dispersion B-1 were used. The above mixed powder contained 99.64% by mass of TFE units and 0.36% by mass of PPVE units based on all polymerization units. The melting points of the above mixed powder were 315 °C and 328 °C, the tensile breaking strength was 15 MPa, the tensile breaking strain was 353%, the average secondary particle diameter was 25 μm, D10 was 9 μm, D90 was 52 μm, and the content of the low molecular weight fluorine-containing compound (surfactant containing fluorine with an anionic part having a molecular weight of 800 or less) was 1 ppm by mass or less. Since the thickness of the molded product increased before and after firing and the shape was maintained, it was determined that the above mixed powder did not exhibit melt fluidity.

[0222] Comparative Example 1 When a tensile test was conducted in the same manner as in Example 1 using 35 g of fluororesin powder A-1 (melting point 328 °C), the tensile breaking strength was 9 MPa, the tensile breaking strain was 145%, the average secondary particle diameter was 23 μm, D10 was 8 μm, and D90 was 48 μm.

[0223] Example 3 50 g of fluororesin powder A-1, 14 g of PFA aqueous dispersion B-1, and 80 g of fluororesin aqueous dispersion C-1 were used to obtain a mixed powder in the same manner as in Example 1. The above mixed powder contained 99.928% by mass of TFE units and 0.072% by mass of PPVE units based on all polymerization units. The melting points of the above mixed powder were 312 °C, 329 °C, and 337 °C, the tensile breaking strength was 19 MPa, and the tensile breaking strain was 377%. Since the thickness of the molded product increased before and after firing and the shape was maintained, it was determined that the above mixed powder did not exhibit melt fluidity.

[0224] Example 4 50 g of fluororesin powder A-1, 36 g of PFA aqueous dispersion B-1, and 75 g of fluororesin aqueous dispersion C-1 were used to obtain a mixed powder in the same manner as in Example 1. The above mixed powder contained 99.82% by mass of TFE units and 0.18% by mass of PPVE units based on all polymerization units. The melting points of the above mixed powder were 312 °C, 329 °C, and 337 °C, the tensile breaking strength was 25 MPa, and the tensile breaking strain was 531%. Since the thickness of the molded product increased before and after firing and the shape was maintained, it was determined that the above mixed powder did not exhibit melt fluidity.

[0225] Comparative Example 2 50 g of fluororesin powder A-1 and 83 g of fluororesin aqueous dispersion C-1 were used to obtain a mixed powder in the same manner as in Example 1. The melting points of the above mixed powder were 329 °C and 337 °C, the tensile breaking strength was 12 MPa, and the tensile breaking strain was 278%.

[0226] Example 5 75 g of fluororesin powder A-1 and 25 g of PFA powder B-2 were mixed using a wonder crusher WC-3 at a rotation speed of 6900 rpm for 60 seconds to obtain a mixed powder (fluororesin composition). The above mixed powder contained 99.1% by mass of TFE units and 0.9% by mass of PPVE units based on all polymerization units. The melting points of the above mixed powder were 298 °C and 329 °C, the tensile breaking strength was 16 MPa, the tensile breaking strain was 297%, the average secondary particle diameter was 22 μm, D10 was 4 μm, and D90 was 64 μm. Since the thickness of the molded product increased before and after firing and the shape was maintained, it was determined that the above mixed powder did not exhibit melt fluidity.

[0227] Example 6 50 g of fluororesin powder A-1, 3 g of FEP powder B-4, and 47 g of fluororesin powder C-2 were used to obtain a mixed powder in the same manner as in Example 5. The above mixed powder contained 99.64% by mass of TFE units and 0.36% by mass of HFP units based on all polymerization units. The melting points of the above mixed powder were 263 °C, 329 °C, and 345 °C, the tensile breaking strength was 22 MPa, the tensile breaking strain was 404%, the average secondary particle diameter was 27 μm, D10 was 8 μm, and D90 was 64 μm. Since the thickness of the molded product increased before and after firing and the shape was maintained, it was determined that the above mixed powder did not exhibit melt fluidity.

[0228] Example 7 After 90 g of fluororesin powder A-1 and 36 g of PFA aqueous dispersion B-1 were shaken in a flask, methanol was added for coagulation, filtered, and washed with water and methanol to take out the wet powder. The obtained wet powder was dried in an electric furnace at 150 °C for 15 hours to remove water. The dried powder and fluororesin powder C-3 were mixed and pulverized at 2900 rpm for 60 seconds using a wonder crusher WC-3 to obtain a mixed powder (fluororesin composition). The above mixed powder contained 99.82% by mass of TFE units and 0.18% by mass of PPVE units based on all polymerization units. The melting points of the above mixed powder were 314 °C, 329 °C, and 342 °C, the tensile breaking strength was 13 MPa, the tensile breaking strain was 344%, the average secondary particle diameter was 26 μm, D10 was 9 μm, and D90 was 61 μm. Since the thickness of the molded product increased before and after firing and the shape was maintained, it was determined that the above mixed powder did not exhibit melt fluidity.

[0229] Example 8 50 g of fluororesin powder A-1, 8 g of FEP powder B-5, and 42 g of fluororesin powder C-2 were used to obtain a mixed powder in the same manner as in Example 5. The above mixed powder contained 99.04% by mass of TFE units and 0.96% by mass of HFP units based on all polymerized units. The melting points of the above mixed powder were 263°C, 329°C, and 345°C, the tensile breaking strength was 21 MPa, the tensile breaking strain was 342%, the average secondary particle diameter was 28 μm, D10 was 9 μm, and D90 was 62 μm. Since the thickness of the molded product increased before and after firing and the shape was maintained, it was determined that the above mixed powder did not exhibit melt fluidity.

[0230] Example 9 90 g of fluororesin powder A-2 and 10 g of PFA powder B-3 were used to obtain a mixed powder in the same manner as in Example 5. The above mixed powder contained 99.64% by mass of TFE units and 0.36% by mass of PPVE units based on all polymerized units. The melting points of the above mixed powder were 314°C and 329°C, the tensile breaking strength was 12 MPa, and the tensile breaking strain was 275%. Since the thickness of the molded product increased before and after firing and the shape was maintained, it was determined that the above mixed powder did not exhibit melt fluidity.

[0231] Example 10 50 g of fluororesin powder A-1, 40 g of fluororesin powder A-2, and 10 g of PFA powder B-3 were used to obtain a mixed powder in the same manner as in Example 5. The above mixed powder contained 99.64% by mass of TFE units and 0.36% by mass of PPVE units based on all polymerized units. The melting points of the above mixed powder were 314°C, 329°C, and 342°C, the tensile breaking strength was 23 MPa, and the tensile breaking strain was 363%. Since the thickness of the molded product increased before and after firing and the shape was maintained, it was determined that the above mixed powder did not exhibit melt fluidity.

Claims

1. A fluororesin composition that does not exhibit melt fluidity, 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 B that exhibits melt fluidity, and a fluororesin C 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 A is polytetrafluoroethylene; with respect to the fluororesin composition, the content of the fluororesin B is 0.5 to 30% by mass; the tensile breaking strength measured under the following conditions is 17 MPa or more; a fluororesin composition used for compression molding, ram extrusion molding, or isostatic molding (except when used for manufacturing a porous body). (Measurement conditions) 35 g of the fluororesin composition is put into a mold with a diameter of 100 mm, compression molded under the conditions of a pressure of 30 MPa for 1 minute, heated from room temperature to 300 °C in 3 hours, then heated from 300 °C to 370 °C in 4 hours, held at 370 °C for 12 hours, cooled to 300 °C in 5 hours, and then cooled to room temperature in 1 hour. A dumbbell is made by punching out the fired molded body, and the measurement is carried out in accordance with ASTM D1708.

2. The fluororesin composition according to claim 1, wherein the fluororesin B has an MFR of 0.25 g / 10 min or more.

3. The fluororesin composition according to claim 1 or 2, wherein the fluororesin B is a fluororesin having a melting point of 320 °C or less.

4. The fluororesin composition according to any one of claims 1 to 3, having one or more melting points in the temperature range of less than 333 °C and one or more melting points in the temperature range of 333 to 360 °C.

5. The fluororesin composition according to any one of claims 1 to 4, comprising a tetrafluoroethylene unit and a modified monomer unit based on a modified monomer copolymerizable with tetrafluoroethylene, and the amount of the modified monomer unit is 1.0% by mass or less with respect to all polymerized units.

6. The fluororesin composition according to any one of claims 1 to 5, having an average secondary particle diameter of 5 to 700 μm.

7. The fluororesin composition according to any one of claims 1 to 6, wherein the content of the low molecular weight fluorine-containing compound is 1 mass ppm or less with respect to the fluororesin composition.

8. The fluororesin composition according to any one of claims 1 to 7, which is in powder form.

9. The fluororesin composition according to any one of claims 1 to 8, which is a powder for compression molding.

10. The fluororesin composition according to any one of claims 1 to 9, wherein the tensile fracture strain measured under the following conditions is 150% or more. (Measurement conditions) 35 g of the fluororesin composition is put into a mold with a diameter of 100 mm, compression molded under the conditions of a pressure of 30 MPa for 1 minute, heated from room temperature to 300 °C over 3 hours, then heated from 300 °C to 370 °C over 4 hours, held at 370 °C for 12 hours, then cooled to 300 °C over 5 hours, and then cooled to room temperature over 1 hour. A dumbbell created by punching out a molded body fired by this process is used for measurement in accordance with ASTM D1708.

11. A molded body obtained by compression molding and firing the fluororesin composition according to any one of claims 1 to 10.

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