Molding material

Abstract

The present invention addresses the problem of providing a molding material that has a large viscosity reduction rate at the initial stage of heating.　A molding material according to the present invention contains a fluorine-containing resin that comprises a unit based on tetrafluoroethylene, a unit based on perfluoro(alkyl vinyl ether), and a unit based on hexafluoropropylene. The content of the unit based on the perfluoro(alkyl vinyl ether) is 1.0-5.0 mass% with respect to all units of the fluorine-containing resin, the content of the unit based on the hexafluoropropylene is 2.4-4.8 mass% with respect to all units of the fluorine-containing resin, and the melt flow rate of the molding material is 10.0-30.0 g / 10 min as measured under the condition of a temperature of 372°C in accordance with ASTM D1238. The total number of functional groups of the fluorine-containing resin is less than 100 per 106 of the main chain carbon atoms of the fluorine-containing resin, and a specific parameter A is 0.005 (h- 1) or more.

Description

molding material

[0001] The present invention relates to a molding material.

[0002] Tetrafluoroethylene / perfluoro(alkyl vinyl ether) copolymer (hereinafter also referred to as "PFA") is known as a fluororesin that is excellent in mechanical properties, chemical properties, electrical properties, etc. and is also melt-processable. For example, Patent Document 1 discloses a fluorine-containing copolymer that contains tetrafluoroethylene units, hexafluoropropylene units, and perfluoro(propyl vinyl ether) units, in which the content of hexafluoropropylene units is 6.0 to 7.6 mass% relative to all monomer units, the content of perfluoro(propyl vinyl ether) units is 1.2 to 1.9 mass% relative to all monomer units, and the melt flow rate at 372°C is 2.8 to 4.4 g / 10 min.

[0003] Japanese Patent Application Laid-Open No. 2022-132233

[0004] When PFA is used as a constituent material of a molded body, it is required to have excellent melting properties, more specifically, to have a large decrease in viscosity in a short time when heated. When the present inventors evaluated the PFA described in Patent Document 1, they found that the rate of viscosity decrease during initial heating was small and there was room for improvement.

[0005] Therefore, an object of the present invention is to provide a molding material that exhibits a high rate of viscosity reduction in the initial stage of heating.

[0006] As a result of intensive research into the above-mentioned problems, the present inventors have found that a molding material containing a fluorine-containing resin containing units based on tetrafluoroethylene, units based on perfluoro(alkyl vinyl ether), and units based on hexafluoropropylene has a high rate of viscosity decrease in the initial stage of heating when the contents of units based on perfluoro(alkyl vinyl ether) and units based on hexafluoropropylene are within predetermined ranges, the melt flow rate measured under predetermined conditions is 10.0 to 30.0 g / 10 min, the total number of functional groups possessed by the fluorine-containing resin is within a predetermined range, and a specific parameter A is within a predetermined range, thereby completing the present invention.

[0007] That is, the inventors have found that the above-mentioned problems can be solved by the following constitution: [1] A molding material containing a fluororesin containing units based on tetrafluoroethylene, units based on perfluoro(alkyl vinyl ether), and units based on hexafluoropropylene, wherein the content of the units based on perfluoro(alkyl vinyl ether) is 1.0 to 5.0 mass% based on all units of the fluororesin, the content of the units based on hexafluoropropylene is 2.4 to 4.8 mass% based on all units of the fluororesin, the melt flow rate of the molding material measured at a temperature of 372°C in accordance with ASTM D1238 is 10.0 to 30.0 g / 10 min, and the total number of functional groups possessed by the fluororesin is 10 to 15.0 mass%. ６ The predetermined parameter A is 0.005 (h －１) or more. [2] The molding material according to [1], wherein the perfluoro(alkyl vinyl ether) is perfluoro(propyl vinyl ether). [3] The molding material according to [1] or [2], wherein the content of units based on the perfluoro(alkyl vinyl ether) is 4.6 to 5.0 mass% based on all units of the fluororesin. [4] The molding material according to any of [1] to [3], wherein the content of units based on hexafluoropropylene is 2.6 to 3.0 mass% based on all units of the fluororesin. [5] The molding material according to any of [1] to [4], wherein the content of units based on tetrafluoroethylene is 90.2 to 96.6 mass% based on all units of the fluororesin. [6] The molding material according to any of [1] to [5], wherein the melt flow rate of the molding material is 11.0 to 19.0 g / 10 min. [7] The total number of functional groups possessed by the fluororesin is 10 or less than the number of carbon atoms in the main chain of the fluororesin. ６ [8] The molding material according to any one of [1] to [7], wherein the viscosity reduction rate at the initial stage of heating, as defined by the condition of the following formula (2), is 9,000 Pa or more. Formula (2) Viscosity reduction rate at the initial stage of heating = |(η ＊ ３０ -η ＊ ６ ) / (30-6) | η ＊ ６ is the complex viscosity 6 seconds after the start of measurement when the molding material is measured using a closed biconical die of a rubber processability tester under the conditions of vibration mode, frequency 50 cpm, strain 0.5 deg, and temperature 310°C, and η ＊ ３０ is the complex viscosity 30 seconds after the start of measurement when the molding material is measured using a closed biconical die of a rubber processability tester under the conditions of vibration mode, frequency 50 cpm, strain 0.5 deg, and temperature 310°C.

[0008] According to the present invention, it is possible to provide a molding material that exhibits a high rate of viscosity reduction in the initial stage of heating.

[0009] 1 is a graph showing the relationship between the immersion time and the amount of fluoride ions eluted when a molding material containing a fluorine-containing resin is immersed in an immersion liquid.

[0010] The meanings of terms used in this specification are as follows: A numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0011] "Unit" is a general term for an atomic group derived from one molecule of the above-mentioned monomer formed directly by polymerization of the monomer, and an atomic group obtained by chemically converting a part of the above-mentioned atomic group. Note that, hereinafter, in some cases, a unit derived from an individual monomer will be referred to by the name of the monomer followed by "unit". "TFE unit" is a unit based on tetrafluoroethylene contained in the fluororesin. Furthermore, "PAVE unit" is a unit based on perfluoro(alkyl vinyl ether) contained in the fluororesin, "PPVE unit" is a unit based on perfluoro(propyl vinyl ether) contained in the fluororesin, and "HFP unit" is a unit based on hexafluoropropylene contained in the fluororesin. "Number of functional groups" means the total number of functional groups possessed by the fluororesin, unless otherwise specified.

[0012] [Molding Material] The molding material of the present invention (hereinafter also referred to as "the molding material") comprises a fluorine-containing resin (hereinafter also referred to as "resin F") that contains TFE units, PAVE units, and HFP units, the contents of the PAVE units and HFP units each being within a predetermined range, and that contains a predetermined amount of functional groups. Furthermore, the molding material has a melt flow rate (hereinafter also referred to as "MFR") measured at a temperature of 372°C in accordance with ASTM D1238 that is within a predetermined range, and a parameter A defined by formula (1) described below that is within a predetermined range.

[0013] <Resin F> Resin F contains TFE units based on tetrafluoroethylene (TFE), perfluoro(alkyl vinyl ether) (PAVE) units based on PAVE, and hexafluoropropylene (HFP) units based on HFP.

[0014] As the PAVE, a monomer represented by formula (2) is preferred: CF ２ ═CF—O—Rf １ (2) In formula (2), Rf １ represents a perfluoroalkyl group having 1 to 10 carbon atoms. １ From the viewpoint of superior polymerization reactivity, the number of carbon atoms in the perfluoroalkyl group represented by the formula (I) is preferably 1 to 8, more preferably 1 to 6, still more preferably 1 to 5, and particularly preferably 1 to 3. The perfluoroalkyl group may be linear or branched.

[0015] Specific examples of PAVE include perfluoro(methyl vinyl ether) (PMVE), perfluoro(ethyl vinyl ether) (PEVE), and perfluoro(propyl vinyl ether) (PPVE), with PMVE or PPVE being preferred, and PPVE being more preferred.

[0016] The content of PAVE units is 1.0 to 5.0% by mass relative to all units contained in Resin F. The content of PAVE units is preferably 2.0 to 5.0% by mass, and more preferably 4.6 to 5.0% by mass, relative to all units contained in Resin F, from the viewpoint of achieving a better balance between mechanical strength, melt moldability, raw material cost, and polymerization productivity. Furthermore, from the viewpoint of achieving a superior rate of viscosity reduction during initial heating, the content of PAVE units is preferably 2.0 to 4.9% by mass, and more preferably 3.0 to 4.7% by mass, relative to all units contained in Resin F. Resin F may contain two or more types of PAVE units. When Resin F contains two or more types of PAVE units, this means that the total content of the two or more types of PAVE units is within the above range.

[0017] The content of HFP units is 2.4 to 4.8% by mass relative to all units contained in Resin F. The content of HFP units is preferably 2.4 to 3.0% by mass, more preferably 2.6 to 3.0% by mass, and even more preferably 2.65 to 2.8% by mass, relative to all units contained in Resin F, in that a better balance between melt-moldability and polymerization productivity is achieved.

[0018] The content of TFE units is 96.6% by mass or less, based on all units contained in Resin F. The content of TFE units may be, for example, 90.2 to 96.6% by mass, based on all units contained in Resin F. In terms of better chemical resistance, raw material costs, and polymerization productivity, the content is preferably 90.2 to 95.6% by mass, more preferably 92.0 to 93.0% by mass, and even more preferably 92.4 to 92.75% by mass.

[0019] Resin F may contain, in addition to TFE units, PAVE units, and HFP units, units based on other monomers copolymerizable with TFE, PAVE, and HFP. Examples of such other monomers include ethylene, vinylidene fluoride (VdF), and CX １ X ２ =CX ３ (CF ２ ) ｎ X ４ (In the formula, X １ , X ２ and X ３ each independently represents a hydrogen atom or a fluorine atom; X ４ represents a hydrogen atom, a fluorine atom, or a chlorine atom, and n represents an integer of 1 to 10 (excluding HFP), and ２ =CF-OCH ２ -Rf ２ (wherein, Rf ２ represents a perfluoroalkyl group having 1 to 5 carbon atoms. When Resin F contains units based on other monomers, the content of the units based on other monomers is preferably 1.0 mass % or less, and more preferably 0.1 to 0.4 mass %, based on the total units contained in Resin F.

[0020] From the viewpoint of better abrasion resistance during repeated use, it is particularly preferred that Resin F does not contain units based on the other monomers and contains only TFE units, PAVE units and HFP units. In this case, the total content of TFE units, PAVE units and HFP units is 100.0 mass% based on all units contained in Resin F.

[0021] The contents of TFE units, PAVE units, HFP units and units based on other monomers in the fluororesin are１９ The molar ratio of each unit measured by the above method can be converted into a mass ratio based on the chemical structural formula, whereby the content of each unit can be determined.

[0022] (Number of Functional Groups) The number of functional groups possessed by Resin F is 10 when the number of carbon atoms in the main chain of Resin F is 10. ６ The number of functional groups is less than 100 per unit. ６ The number of functional groups per unit area is preferably less than 60, more preferably less than 20, and even more preferably less than 6. When the number of functional groups in the fluorine-containing resin is within the above range, fluoride ions are easily eluted from the molding material, and a resin F having a large parameter A can be more easily produced.

[0023] Infrared spectroscopy can be used to identify the type of functional group in a fluororesin and measure the number of functional groups. Specifically, the number of functional groups is measured by the following method. First, a fluororesin is molded by hot pressing at 330°C to produce a film with a thickness of 0.25 to 0.30 mm. This film is analyzed by Fourier transform infrared spectroscopy (FT-IR) to obtain an infrared absorption spectrum of the fluororesin. Separately, an infrared absorption spectrum (base spectrum) of a completely fluorinated resin with no functional groups present is obtained, and a difference spectrum between the infrared absorption spectrum of the fluororesin and the base spectrum is obtained. From the absorption peaks of the functional groups appearing in this difference spectrum, the number of functional groups in 1 x 10 carbon atoms constituting the main chain of the fluororesin can be calculated according to the following formula (A): ６ The number of functional groups per molecule, N, is calculated.

[0024] N = I x K / t (A) I: absorbance K: correction coefficient t: film thickness (mm)

[0025] For reference, the absorption frequencies, molar absorption coefficients, and correction factors for several functional groups are shown in Table 1. The molar absorption coefficients of functional groups are determined from FT-IR measurement data of low molecular weight model compounds.

[0026]

[0027] In the fluorine-containing resin, -CH ２ CF ２ H, —CH ２ COF, -CH ２ COOH, -CH ２ COOCH ３ and -CH ２ CONH ２ The absorption frequency of -CF is shown in the table. ２ H, -COF, -COOH (free and bonded), -COOCH ３ and -CONH ２ From each absorption frequency, several tens of Kaiser (cm －１ ) becomes lower. For example, the number of -COF becomes lower. ２ Absorption frequency due to COF: 1,883 cm －１ The number of functional groups determined from the absorption peak of -CH ２ Absorption frequency due to COF: 1,840 cm －１ The number of functional groups is the sum of the number of functional groups determined from the absorption peaks of the compounds.

[0028] The functional groups are, for example, functional groups present at the end of the main chain or the end of the side chain of the fluorine-containing resin, and functional groups present in the main chain or the side chain. The number of functional groups is the total number of functional groups. The number of functional groups is expressed as -CF=CF ２ , -CF ２ H, -COF, -COOH, -COOCH ３ , -CONH ２ and -CH ２ It may be the total number of OH.

[0029] The functional group is introduced into the fluorine-containing resin by, for example, a chain transfer agent or a polymerization initiator used in the production of the fluorine-containing resin. More specifically, when an alcohol is used as a chain transfer agent or a —CH ２ When a peroxide having an OH structure is used, -CH ２OH is introduced. Furthermore, by polymerizing a monomer having a functional group, the functional group is introduced into the side chain terminal of the fluorine-containing resin. When the number of functional groups in the fluorine-containing resin exceeds a predetermined range, the number of functional groups can be reduced by a fluorination treatment. The number of functional groups in Resin F can be adjusted by changing the conditions of the fluorination treatment (e.g., treatment time) described below.

[0030] (Melting Point) The melting point of Resin F is preferably 280.0 to 315.0°C, more preferably 280.5 to 295.5°C, even more preferably 281.0 to 295.0°C, particularly preferably 281.0 to 290.0°C, and extremely preferably 286.5 to 290.0°C, from the viewpoint of a better balance between melt moldability and heat resistance. A specific example of a method for adjusting the melting point of Resin F within the above range is a method of lowering the polymerization temperature during the production of Resin F. The melting point of Resin F (fluorine-containing resin) is the temperature corresponding to the endothermic peak when Resin F is heated at a rate of 10°C / min in an air atmosphere using a scanning differential thermal analyzer. The melting point of Resin F may be determined by measuring the melting point of a molding material containing Resin F using the above method.

[0031] The content of resin F contained in this molding material is preferably 70% by mass or more and less than 100% by mass, more preferably 90% by mass or more and less than 100% by mass, and even more preferably 99% by mass or more and less than 100% by mass, relative to the total mass of this molding material.

[0032] <Other Components> The present molding material may contain other components in addition to resin F. Specific examples of such other components include resins other than resin F, heat stabilizers, antioxidants, colorants, ultraviolet absorbers, fillers, crosslinking agents, crosslinking aids, and organic peroxides. When the present molding material contains other components, the content of the other components is preferably 0.0000001 to 70 parts by mass, more preferably 0.0000005 to 60 parts by mass, and even more preferably 0.000001 to 50 parts by mass, per 100 parts by mass of resin F in the present molding material.

[0033] <Physical Properties of Molding Material> (Melt Flow Rate) The MFR of the molding material is 10.0 to 30.0 g / 10 min. The MFR of the molding material refers to the mass of molding material flowing through an orifice with a diameter of 2.095 mm and a length of 8 mm in 10 minutes, measured at a temperature of 372°C and a load of 5 kg in accordance with ASTM D1238. A specific example of a method for adjusting the MFR of the molding material within the above range is a method of adjusting the molecular weight of the fluororesin contained in the molding material. The higher the molecular weight of the fluororesin, the lower the MFR. The MFR of the molding material is preferably 11.0 to 19.0 g / 10 min, more preferably 12.0 to 17.0 g / 10 min, even more preferably 14.5 to 17.0 g / 10 min, and extremely preferably 14.5 to 15.5 g / 10 min, in order to achieve a better balance between melt moldability and mechanical strength.

[0034] (Parameter A) The molding material has a parameter A defined by the following formula (1) of 0.005 (h －１ ) or more. Formula (1) A={F(t1) / t1} / F(t2) F(t1) is the amount of fluoride ion elution (μg / L) obtained by immersing 3 g of the molding material in 10 mL of a mixed liquid containing methanol and water in a volume ratio of 1:1 at 85°C for 24 hours, recovering the mixed liquid, and measuring the fluoride ion concentration contained in the mixed liquid, F(t2) is the amount of fluoride ion elution (μg / L) obtained by immersing 3 g of the molding material in 10 mL of the mixed liquid at 85°C for 336 hours, recovering the mixed liquid, and measuring the fluoride ion concentration contained in the mixed liquid, and t1 is 24 (h).

[0035] The technical significance of parameter A will be explained below with reference to the drawings. Fig. 1 is a graph showing the relationship between the immersion time and the amount of fluoride ions eluted from a molding material containing a fluorine-containing resin when the molding material is immersed in an immersion liquid. In the graph of Fig. 1, the horizontal axis represents the immersion time t of the molding material, and the vertical axis represents the amount of fluoride ions eluted F(t) from the molding material into the immersion liquid during the period from the start of immersion in the immersion liquid until the lapse of the immersion time t. As shown by the curve F in the graph, the amount of elution F(t) increases immediately after the start of immersion (t = 0 → t １) increases rapidly, but as the immersion time t passes (t = t １ →t ２ ) increase becomes slower, and when the immersion time t becomes large enough (t>t ２ ) constant elution amount (F ０ ) The relationship between the immersion time t and the amount of elution F(t) can be expressed by the following formula (X): Formula (X) F(t) = F ０ (1-e －ｋｔ ) In the above model formula, F ０ and k is a constant. ０ is the amount of fluoride ions contained in the molding material and is considered to correspond to the amount of fluoride ions that can be dissolved by the immersion liquid. On the other hand, the larger the value of the constant k, the more fluoride ions will be dissolved in the same immersion time. Therefore, it is considered to be an index showing the ease of elution of fluoride ions from the molding material into the immersion liquid in the immersion test. Here, the constant F ０ The larger the amount of elutable fluoride ions contained in the molding material, the larger the absolute value of the eluted amount of fluoride ions. However, the constant k is ０ That is, it is considered that the amount of elutable fluoride ions is not dependent on the amount of elutable fluoride ions.

[0036] Here, from the following formula (Y) obtained by differentiating the above formula (X), the slope (dF(0) / dt) of the curve F when the immersion time t = 0 is determined by the relationship between k and F. ０ Equation (Y) dF(t) / dt = kF ０ e －ｋｔ Therefore, as an approximation of the slope (dF(0) / dt), the immersion time t is t １ (24 hours) １ ) for immersion time t １ Dividing by {F(t １ ) / t １} and constant F ０ As an approximation of t, the immersion time t is t ２ (336 hours) ２ ), the following equation holds: k = (dF(0) / dt) / F ０ ≒{F(t１ ) / t １} / F(t ２ ) = A In this way, the parameter A is an approximation of the constant k, and can be said to be a parameter that indicates the ease of elution of fluoride ions from the molding material into the immersion liquid during the immersion test (especially immediately after the start of immersion). Furthermore, as described above, the parameter A is thought to be independent of the amount of elutable fluoride ions contained in the molding material.

[0037] The inventors have found that the parameter A is 0.005 (h －１ It has been surprisingly found that the molding material of the present invention having a parameter A of 0.005 (h ) or more exhibits the excellent effect of a high viscosity reduction rate in the initial stage of heating. －１ ) or more, the details of the mechanism by which the rate of viscosity reduction in the initial stage of heating becomes large have not yet been clarified, but since the molding material of the present invention has an excellent rate of viscosity reduction in the initial stage of heating, for example, the molding material is more likely to become a more uniform molten material when it is heated and conveyed to a screw for melt-kneading, thereby reducing dimensional defects and the like during molding processing.

[0038] Parameter A is 0.005 (h －１ The molding material of the present invention having a viscosity of 0.011 (h ) or more can be produced, for example, by copolymerizing TFE, PAVE, and HFP, adjusting the amounts of each monomer used so that the contents of PAVE units and HFP units fall within the above ranges, setting the polymerization conditions so that the MFR falls within the above ranges, and then selecting the type of polymerization medium and the stirring conditions as described below. The parameter A of the molding material of the present invention is set to 0.011 (h ) or more from the viewpoint of improving the initial viscosity reduction rate. －１ ) or more, and 0.013 (h －１ ) or more is more preferable.

[0039] (Viscosity reduction coefficient at the beginning of heating) The molding material has excellent moldability due to its large viscosity reduction rate at the beginning of heating. The viscosity reduction rate at the beginning of heating is defined by the following formula (2). Formula (2) Viscosity reduction rate at the beginning of heating = |(η ＊ ３０ -η ＊ ６ ) / (30-6) | η ＊６ is the complex viscosity 6 seconds after the start of measurement when the molding material is measured using a closed biconical die of a rubber processability tester under the conditions of vibration mode, frequency 50 cpm, strain 0.5 deg, and temperature 310°C, and η ＊ ３０ is the complex viscosity 30 seconds after the start of measurement when the molding material is measured using a closed biconical die of a rubber processability tester under conditions of vibration mode, frequency 50 cpm, strain 0.5 deg, and temperature 310°C. The viscosity reduction rate in the initial stage of heating is preferably 9,000 Pa or more, more preferably 10,000 Pa or more, from the viewpoint of quickly melting the molding material and reducing the load on the molding machine. The viscosity reduction rate in the initial stage of heating is preferably 20,000 Pa or less.

[0040] <Method for Producing Molding Material> As a method for producing the present molding material, for example, a method including a step of producing Resin F described below can be mentioned.

[0041] The process for producing Resin F includes a polymerization reaction process in which the above-mentioned monomers (TFE, PAVE, and HFP) are copolymerized. Known polymerization methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization can be used as the polymerization method. Among these, it is preferable to produce Resin F by solution polymerization, since it is easy to obtain a molding material with a larger parameter A. In the production of Resin F, in addition to the above-mentioned monomers, a polymerization initiator, a polymerization medium, a chain transfer agent, and the like can be used.

[0042] The polymerization initiator is preferably a radical polymerization initiator having a half-life of 10 hours at a temperature of 0 to 100°C, and more preferably a radical polymerization initiator having the temperature of 20 to 90°C. Specific examples of the polymerization initiator include the various polymerization initiators exemplified in WO 2013 / 015202. The polymerization initiator may be used alone or in combination of two or more types. The amount of the polymerization initiator used is preferably 0.01 to 0.9 parts by mass, more preferably 0.05 to 0.5 parts by mass, per 100 parts by mass of the amount of the monomer used.

[0043] The polymerization medium may be water, an organic solvent, or a mixture of water and an organic solvent. The organic solvent may be, for example, a fluorine-based solvent such as perfluorocarbon, hydrofluorocarbon, or hydrofluoroether, or an alcohol. Specific examples of the organic solvent include the polymerization mediums exemplified in International Publication No. 2013 / 015202.

[0044] The fluorine-based solvent is preferably a perfluorocarbon, a hydrofluorocarbon, or a hydrofluoroether, and CF ３ CH ２ OCF ２ CF ２ H (AE-3000), C ６ F １３ H (AC-2000), C ７ F １５ H, perfluorocyclobutane, HCF ２ CF ２ CH ２ OCF ２ CF ２ H, C.F. ３ CFHCF ２ OCF ３ , C.F. ３ (CF ２ ) ２ OCH ３ , (CF ３ ) ２ CFOCH ３ , C.F. ３ (CF ２ ) ３ OCH ３ , (CF ３ ) ２ CFCF ２ OCH ３ , C.F. ３ (CF ２ ) ３ OCH ２ CH ３ , (CF ３ ) ２ CFCF ２ OCF ２ CH ３ or CF ３ CF ２ CF (OCH ３ )CF(CF ３ )２ are more preferred, and AE-3000, AC-2000, CF ３ (CF ２ ) ３ OCH ３ , (CF ３ ) ２ CFCF ２ OCH ３ , C.F. ３ (CF ２ ) ３ OCH ２ CH, (CF ３ ) ２ CFCF ２ OCF ２ CH ３ or CF ３ CF ２ CF (OCH ３ )CF(CF ３ ) ２ is more preferred, with AE-3000 or AC-2000 being particularly preferred. Examples of alcohols that can be used as the polymerization medium include aliphatic tertiary alcohols, with tert-butyl alcohol being preferred. The term "aliphatic tertiary alcohol" refers to an alcohol that does not have an aromatic ring and in which the carbon atom bonded to the oxygen atom of the alcoholic hydroxyl group is a tertiary carbon atom.

[0045] The polymerization medium may be used alone or in combination of two or more. The polymerization medium preferably contains at least one of a fluorine-based solvent and an alcohol, more preferably both a fluorine-based solvent and an alcohol, in that a molding material with a larger parameter A can be produced. Among these, a polymerization medium containing at least one of the above-mentioned preferred fluorine-based mixed solvents and the above-mentioned preferred alcohols is more preferred, a polymerization medium containing both the above-mentioned preferred fluorine-based mixed solvents and the above-mentioned preferred alcohols is particularly preferred, and a polymerization medium containing both AC-2000 and tert-butyl alcohol is most preferred. When the polymerization medium contains both a fluorine-based solvent and an alcohol, the content of the alcohol contained in the polymerization medium is preferably 5 to 50% by mass, more preferably 10 to 40% by mass, based on the total content of the fluorine-based solvent and the alcohol.

[0046] The polymerization medium may further contain water in addition to a fluorine-based solvent and an organic solvent such as alcohol. When the polymerization medium is a mixed solvent of water and an organic solvent, the content of the organic solvent is preferably 10% by mass or more and less than 100% by mass based on the total amount of the polymerization medium. The amount of the polymerization medium used is preferably 3 times or more, more preferably 5 times or more, based on the total amount of the monomers used, in terms of mass ratio. Also, it is preferably 20 times or less, more preferably 17 times or less.

[0047] The chain transfer agent has a large chain transfer constant and can be added in a small amount, and is therefore preferably an alcohol (more preferably an aliphatic primary or secondary alcohol) such as methanol, ethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoropropanol, 1,1,1,3,3,3-hexafluoroisopropanol, or 2,2,3,3,3-pentafluoropropanol; a hydrocarbon such as n-pentane, n-hexane, or cyclohexane; or CF ２ H ２ Preferred are hydrofluorocarbons such as acetone; ketones such as acetone; mercaptans such as methyl mercaptan; esters such as methyl acetate and ethyl acetate; and ethers such as diethyl ether and methyl ethyl ether. Among these, at least one selected from the group consisting of aliphatic primary or secondary alcohols, hydrocarbons, and hydrofluorocarbons is preferred because of its higher chain transfer constant and the high stability of the end groups of Resin F. At least one selected from the group consisting of aliphatic primary or secondary alcohols and hydrocarbons is more preferred, and aliphatic primary alcohols are even more preferred. Among aliphatic primary alcohols, methanol or ethanol is preferred, with methanol being more preferred due to its reactivity and availability. Two or more chain transfer agents may be used. The amount of chain transfer agent used is preferably 0.001 times or more, more preferably 0.005 times or more, by mass, relative to the total amount of monomers used. Also, 5 times or less is preferred, and 4 times or less is more preferred.

[0048] In the polymerization reaction step of copolymerizing the monomers, the polymerization temperature is preferably 15 to 60°C, more preferably 20 to 58°C, and even more preferably 25 to 55°C. When the polymerization temperature is equal to or higher than the lower limit, the polymerizability is excellent. When the polymerization temperature is equal to or lower than the lower limit, the melting point of Resin F can be improved. The polymerization pressure is preferably 0.5 to 3.0 MPa, more preferably 0.9 to 2.5 MPa. The polymerization time is preferably 1 to 12 hours.

[0049] In terms of being able to produce a molding material with a large parameter A, it is preferable to carry out a stirring treatment in which a reaction solution containing the monomers is subjected to shear force in the polymerization reaction step in which the monomers are copolymerized. The stirring treatment can be carried out, for example, by charging a reaction solution containing the monomers into a reaction vessel equipped with a stirring blade and copolymerizing the monomers while rotating the stirring blade. Specific examples of the shape of the stirring blade include a paddle blade, a propeller blade, a disk blade, a Pfaudle blade, an anchor blade, a double helical ribbon blade, a turbine blade, and a disk turbine blade. The diameter of the stirring blade is d [m], the rotation speed of the stirring blade is n [revolutions per second], and the charged volume of the polymerization medium is V [m ３ ], and the parameter B calculated by the following formula (B) is 0.20 m in that a molding material with a large parameter A can be produced. ２ / s ３ More than 0.65m is preferable. ２ / s ３ More preferably, 0.75 m or more ２ / s ３ More preferably, 1.60 m or more ２ / s ３ More than 5.0 m is particularly preferred. ２ / s ３ The following is preferred: B=n ３ d ５ / V (B) It is preferable to carry out the stirring treatment under conditions where the parameter B is within the above range. Parameter B represents the stirring power per unit volume of the polymerization medium. The rotation speed of the stirring blade is preferably 450 rpm or less. The rotation speed of the stirring blade may be constant during stirring or may change during stirring.

[0050] When an aqueous dispersion containing a fluororesin is obtained by polymerization, the fluororesin can be recovered by coagulating the fluororesin contained in the aqueous dispersion, washing, and drying. When the fluororesin is obtained as a slurry by polymerization, the fluororesin can be recovered by removing the slurry from the reaction vessel, washing, and drying. By drying, the fluororesin can be recovered in the form of a powder.

[0051] The fluorine-containing resin obtained by polymerization may be subjected to a fluorination treatment. By the fluorination treatment, —COOH, —COOCH ３ , -CH ２ OH, -COF, -CF=CF ２ , -CONH ２ and -CF ２ Therefore, even if the total number of functional groups (number of functional groups) of the fluororesin obtained by the polymerization reaction exceeds a predetermined range, the number of functional groups of the fluororesin can be easily adjusted by the fluorination treatment.

[0052] The fluorination treatment is carried out by contacting the unfluorinated fluorine-containing resin with a fluorine-containing compound. The fluorine-containing compound may be a fluorine radical source that generates fluorine radicals under the fluorination treatment conditions. Examples of the fluorine radical source include F ２ Gas, N ２ F ２ and halogen fluorides (e.g., IF ５ , ClF ３ ) are listed.

[0053] F ２ The concentration of the fluorine radical source such as gas may be 100% by volume. ２ It is preferable to use a mixed gas obtained by diluting with an inert gas so that the gas concentration is 5 to 50% by volume (more preferably 15 to 30% by volume). Examples of the inert gas include nitrogen gas, helium gas, and argon gas, but nitrogen gas is preferable from an economical standpoint.

[0054] The fluorination treatment is usually carried out at a temperature below the melting point of the fluororesin, preferably 20 to 240°C, more preferably 100 to 235°C. The fluorination treatment may be carried out by contacting the molten fluororesin with a fluorine-containing compound. As a specific method of the fluorination treatment, for example, a shelf on which the fluororesin is placed is placed in an oven, and the inside of the oven is heated to F ２ Examples of suitable methods include filling a column with a gas or the above-mentioned mixed gas and heating it for a certain period of time. Another example is a method in which a gas or the above-mentioned mixed gas is passed through a flow column packed with fluororesin pellets while heating the column for a certain period of time. The treatment time for the fluorination treatment varies appropriately depending on the number of functional groups in the fluororesin before the fluorination treatment, the target number of functional groups, and the fluorination treatment method, but is, for example, 0.5 to 30 hours, and preferably 1 to 24 hours. Resin F is preferably produced by obtaining a fluororesin by copolymerizing monomers, and then subjecting the obtained fluororesin to the above-mentioned fluorination treatment.

[0055] The method for producing the molding material may, if necessary, include a step of melt-kneading the resin F produced by the above method with the other components by a known method.

[0056] [Molded Body] A molded body can be obtained by molding the present molding material. The present molding material exhibits a rapid rate of viscosity reduction during initial heating and excellent melting properties. Therefore, by using the present molding material, a uniform melt can be obtained upon heating, reducing the occurrence of dimensional defects during molded body production. Specific examples of molded bodies include injection-molded bodies obtained by injection molding, extrusion-molded bodies obtained by extrusion, blow-molded bodies obtained by blow molding, transfer-molded bodies obtained by transfer molding, press-molded bodies obtained by press molding, rotation-molded bodies obtained by rotation-molding, and coatings obtained by electrostatic coating. Press-molded bodies obtained by press molding are preferred as molded bodies. Injection-molded bodies are also preferred because they can be obtained with beautiful appearance without corroding the mold used for molding.

[0057] Examples of the form of the molded product include pellets and powder. Pellets can be molded using known methods using the molding material. Examples of pellet molding methods include extruding the molding material while melting it using a single-screw extruder, twin-screw extruder, or tandem extruder, cutting it to a predetermined length, and molding it into pellets. The extrusion temperature during melt extrusion varies depending on the melt viscosity of the fluororesin contained in the molding material and the manufacturing method, but is preferably between the melting point of the fluororesin + 20°C and the melting point of the fluororesin + 140°C. The molten and extruded molding material can be cut using conventional methods such as strand cutting, hot cutting, underwater cutting, and sheet cutting. The resulting pellets may be heated to remove volatiles from the pellets (degassing treatment). The resulting pellets may be treated by contacting them with hot water at 30 to 200°C, steam at 100 to 200°C, or hot air at 40 to 200°C.

[0058] Specific examples of molded articles include nuts, bolts, joints, films, bottles, gaskets, wire coating materials, tubes, hoses, pipes, valves, sheets, seals, packing, tanks, rollers, containers, cocks, connectors, filter housings, filter cages, flow meters, pumps, wafer carriers, and wafer boxes.

[0059] The molding material or the above-mentioned molded article can be used for the following purposes. Fluid transfer components for food manufacturing equipment, such as food packaging films, lining materials, packings, sealing materials, and sheets for fluid transfer lines used in food manufacturing processes; chemical liquid transfer components, such as chemical stoppers, packaging films, lining materials, packings, sealing materials, and sheets for fluid transfer lines used in chemical manufacturing processes; inner lining components for chemical liquid tanks and piping in chemical plants or semiconductor factories; fuel transfer components, such as O-rings, tubes, packings, valve core materials, hoses, and sealing materials used in automotive fuel systems and peripheral devices, and hoses and sealing materials used in automotive automatic transmissions; carburetor flange gaskets, shaft seals, valve stem seals, sealing materials, and hoses used in automotive engines and peripheral devices, as well as other automotive components, such as automotive brake hoses, air conditioner hoses, radiator hoses, and wire coating materials; chemical liquid transfer components for semiconductor manufacturing equipment, such as O-rings, tubes, packings, valve core materials, hoses, sealing materials, rolls, gaskets, diaphragms, and fittings; coating and ink components such as paint rolls, hoses, tubes, and ink containers for coating equipment; food and beverage transport components such as tubes, hoses, belts, packing, and joints, such as food and beverage tubes or food and beverage hoses, food packaging materials, and glass cooking equipment; waste liquid transport components such as tubes and hoses for transporting waste liquid; high-temperature liquid transport components such as tubes and hoses for transporting high-temperature liquids; steam piping components such as tubes and hoses for steam piping; anti-corrosion tapes for piping, such as tapes wrapped around piping on ship decks, etc.; various coating materials such as electric wire coating materials, optical fiber coating materials, and transparent surface coating materials and backing agents applied to the light-incident surface of photovoltaic elements in solar cells; sliding components such as diaphragms and various packings for diaphragm pumps; agricultural films, carrier films for fuel cells, and weather-resistant covers for various roofing materials and side walls, etc.; interior materials used in the construction field, and glass coating materials such as non-flammable fire-resistant safety glass; lining materials such as laminated steel sheets used in home appliances, etc.

[0060] In particular, the molded article can be suitably used as piping components (e.g., piping, joints, gaskets, and packings), tubes, or films for transporting fluids. The molded article can also be suitably used as a wire coating material. A specific example of use is a coated electric wire comprising a core wire and a coating layer made of the molded article, which is provided around the core wire. A coated electric wire having a coating layer made of the molded article exhibits excellent electrical properties because the core wire is resistant to corrosion and exhibits little change in outer diameter, and is therefore suitable for use as a high-frequency transmission cable, flat cable, heat-resistant cable, or the like. Such a coated electric wire can be produced, for example, by melt-extrusion molding the molding material onto a core wire to form a coating layer.

[0061] The above-mentioned molded article can also be suitably used as a compressed member. The compressed member is a member used in a compressed and deformed state, and the size and shape of the compressed member are appropriately set depending on the application. The shape of the compressed member may be, for example, annular. The compressed member may have a shape such as a circle, an oval, or a rectangle with rounded corners in a plan view, and may have a through-hole in its center. The compressed member can be used as a piping member for transporting fluids. The compressed member can also be used as a member for constituting a nonaqueous electrolyte battery, and is particularly suitable as a member used in contact with the nonaqueous electrolyte in the nonaqueous electrolyte battery. The compressed member can also be suitably used as a sealing member such as a sealing gasket and a sealing packing, and as an insulating member such as an insulating gasket and an insulating packing. A sealing member is a member used to prevent the leakage of liquid or gas or the intrusion of liquid or gas from the outside. An insulating member is a member used for electrical insulation. The compressed member may be a member used for both sealing and insulating purposes.

[0062] The present invention will be described in detail below with reference to examples. Examples 1 to 3 are working examples, and Example 4 is a comparative example. However, the present invention is not limited to these examples.

[0063] (Content of each unit) The content (mass%) of each unit in the fluororesin contained in the molding material obtained in each example was: １９The molar ratio was calculated using an F-nuclear magnetic resonance spectrometer (AVANCE-III-HD400 manufactured by Bruker Biospin), and the calculated molar ratio was converted into a mass ratio from the chemical structural formula of each unit.

[0064] (MFR (Melt Flow Rate)) For the molding material obtained in each example, the mass (g) of the molding material flowing out of an orifice having a diameter of 2.095 mm and a length of 8 mm in 10 minutes was measured under conditions of a temperature of 372°C and a load of 5 kg using a melt flow tester ("CFT-500EX" manufactured by Shimadzu Corporation) in accordance with ASTM D1238, and this was taken as the MFR (g / 10 min).

[0065] (Melting Point) The melting point (°C) of the fluororesin was determined from the temperature showing the maximum value of the endothermic peak when the molding material obtained in each example was heated from 200°C to 350°C at a rate of 10°C / min in an air atmosphere using a differential scanning calorimeter (DSC204F1 Phoenix, manufactured by NETZSCH).

[0066] (Number of Functional Groups) The molding material obtained in each example was hot-press molded at 330°C using a hydraulic press ("SA-301" manufactured by Tester Sangyo Co., Ltd.) to produce a sample film having a thickness of 0.25 to 0.30 mm. This sample film was scanned 40 times using a Fourier transform infrared spectrometer (FT-IR, "Nicolet iS5" manufactured by ThermoScientific) to obtain an infrared absorption spectrum. Next, the above molding material was subjected to a fluorination treatment described below for a long period of time, and each base sample that was completely fluorinated and had no functional groups was separately prepared. In the same manner as above, a base film was produced from each base sample. The base film was analyzed by the above method to obtain an infrared absorption spectrum (base spectrum), and a difference spectrum between the infrared absorption spectrum of the above sample film and the base spectrum of the base film was obtained. The functional group (-CF=CF) appearing in this difference spectrum was ２ , -CF ２ H, -COF, -COOH, -COOCH ３ , -CONH ２ and -CH ２From the absorption peak of OH, the number of carbon atoms in the main chain of the fluorine-containing resin contained in the sample film was determined according to the following formula (A): ６ The number of functional groups per particle, N, was calculated. The correction coefficients used are as shown in Table 1 above. N = I x K / t (A), I: absorbance, K: correction coefficient, t: film thickness (mm).

[0067] (Parameter A) An immersion test was conducted in which the molding material obtained in each example was immersed in a mixed liquid of methanol and water for a predetermined time, and parameter A was calculated from the amount of fluoride ions eluted from the molding material and the immersion time using the above formula (1). The immersion test conducted will be described in detail below.

[0068] -F(t １ ) / t １ Calculation of t - 3 g of the molding material was weighed into a polypropylene (PP) container with an internal volume of 50 mL, and then 5 mL of methanol and then 5 mL of purified ultrapure water (ultrapure water collected from "Milli-Q IQ7005" manufactured by Merck) were weighed into the container. After sealing the container, it was placed in a thermostatic chamber ("VOS-310C" manufactured by EYELA) at 85°C for 24 hours (t １ After 24 hours, the mixture containing methanol and purified ultrapure water was collected by centrifugation from the test solution containing the molding material, methanol, and purified ultrapure water in the container. The fluoride ion concentration (μg / L) of the resulting mixture was measured using a fluoride ion concentration meter (manufactured by Toko Chemical Research Institute, "TiN-5101"), and the amount of fluoride ion elution F(t １ The fluoride ion concentrations (μg / L) of the methanol and purified ultrapure water used in the immersion test were measured using the above-mentioned fluoride ion concentration meter, and were both below the detection limit.

[0069] -F(t ２ Calculation of F(t) - except that the immersion time was 336 hours １ The same immersion test as in the measurement of fluoride ion elution amount F(t ２ ) was measured.

[0070] - Calculation of parameter A - F(t１ ) / t １ and F(t ２ ) to obtain the parameter A(h ―１ As described above, the parameter A is an index of the extraction rate of fluoride ions extracted by the immersion treatment from among the fluoride ions contained in the molding material.

[0071] (Viscosity Decrease Rate at Initial Stage of Heating) The complex viscosity of the molding material obtained in each example was measured using a closed biconical die of a rubber processability tester (manufactured by Alpha Technologies, "RPA-2000") under the constant conditions of vibration mode, frequency of 50 cpm, strain of 0.5 deg, and temperature of 310°C. The complex viscosity (η ＊ ６ ), complex viscosity (η ＊ ３０ ) and the viscosity reduction rate (Pa) at the initial stage of heating was calculated using the following formula (2): Viscosity reduction rate at the initial stage of heating = |(η ＊ ３０ -η ＊ ６ ) / (30-6) |

[0072] [Example 1] A stainless steel pressure-resistant reactor vessel having an internal volume of 1 L and equipped with anchor blades having a diameter of 93.6 mm was degassed, and then 141.2 g of ultrapure water, CF ３ CH ２ OCF ２ CF ２ H (AGC Corporation "AE-3000", polymerization solvent) 451.9 g, 58.09 g of PPVE, 3.61 g of MeOH (methanol, chain transfer agent), 10.62 g of a 1.0 mass% AE-3000 solution of IPP (isopropyl peroxydicarbonate, polymerization initiator) were charged into a reaction vessel, and the gas phase was degassed under reduced pressure while cooling the reaction vessel in an ice bath. While stirring at a rotation speed of 280 rpm using an anchor blade, 246.2 g of HFP and 118.9 g of TFE were pressed into the reaction vessel, and the liquid phase temperature was raised to 50 ° C. to initiate solution polymerization. The pressure inside the reaction vessel was 1.37 MPa. Parameter B in the stirring treatment of Example 1 was 1.50 m ２ / s ３After the start of polymerization, 14.2 g of TFE was injected every time the pressure inside the reactor decreased by 0.1 MPa. This was repeated twice, and then 9.3 g of TFE was injected the third time. After the third TFE injection, the polymerization was terminated when the gas phase pressure decreased by 0.1 MPa from the pressure after the injection. The polymerization time was 120 minutes. After the polymerization was completed, the temperature inside the reactor was lowered to 23°C, and purging was carried out until the pressure inside the reactor reached atmospheric pressure, followed by thorough nitrogen substitution.

[0073] The reaction vessel was opened, and the obtained slurry was filtered to separate the polymerization medium. The white wet powder was washed with ultrapure water and vacuum dried at 80° C. for 12 hours to obtain 75.9 g of a molding material containing a white fluorine-containing resin. The content (mass%) of each unit in the obtained fluorine-containing resin was TFE unit:HFP unit:PPVE unit=92.8:2.6:4.6.

[0074] (Fluorination Treatment) Next, the obtained molding material was subjected to a fluorination treatment by the following method. The molding material placed in a dedicated tray was placed in a box-type reaction oven, and the oven was then sealed. After evacuating the oven, F ２ The gas concentration was adjusted to 20% by volume. ２ F diluted with gas ２ / N ２ The mixed gas was introduced into the oven. The pressure inside the oven was atmospheric pressure (1 atm), and the temperature was 230°C. ２ / N ２ One hour after the introduction of the mixed gas started, the oven was evacuated and the F ２ / N ２ The mixed gas was introduced, and then the reaction was carried out for 1 hour at 230° C. After the reaction was completed, heating was stopped and N 2 was introduced into the oven. ２ Gas is introduced into the oven to ２ / N ２ Mixed gas is sufficiently N ２ The atmosphere was replaced with gas to obtain molding material A containing fluororesin A. The fluororesin A contained in molding material A was taken out of the oven and subjected to infrared absorption spectroscopy analysis by the method described above to determine the number of functional groups. The number of functional groups of fluororesin A was 10 main chain carbon atoms. ６The number of particles was 10 per particle. The melting point of fluororesin A was 288.0°C, and the MFR of molding material A was 14.2 g / 10 min. In each example, the composition of the fluororesin contained in the non-fluorination-treated molding material was the same as the composition of the fluororesin contained in the fluorination-treated molding material.

[0075] Example 2 69.6 g of a molding material containing a fluorine-containing resin was obtained in the same manner as in Example 1, except that the amount of AE-3000 charged into the reaction vessel before the start of polymerization was changed to 420 g and 23.4 g of tert-butyl alcohol (t-BuOH) was charged into the reaction vessel. The parameter B in the stirring treatment in Example 2 was 1.16 m ２ / s ３ The content (mass%) of each unit in the obtained fluororesin was TFE unit:HFP unit:PPVE unit=92.3:2.9:4.8. Next, fluorination treatment was carried out in the same manner as in Example 1 to obtain molding material B containing fluororesin B of Example 2. Infrared absorption spectroscopy was carried out on fluororesin B by the above-mentioned method to determine the number of functional groups. The number of functional groups of fluororesin B was 10 main chain carbon atoms. ６ The melting point of fluororesin B was 286.0°C, and the MFR of molding material B was 15.9 g / 10 min.

[0076] [Example 3] Instead of AE-3000, C ６ F １３ 460 g of HCl ("AC-2000" manufactured by AGC Inc., polymerization solvent) and 23 g of tert-butyl alcohol were charged into a reaction vessel, and 77.8 g of a molding material containing a fluorine-containing resin was obtained in the same manner as in Example 1, except that the rotation speed of the anchor blade during stirring was changed to 400 rpm. The parameter B in the stirring treatment in Example 3 was 4.40 m ２ / s ３The content (mass%) of each unit in the obtained fluororesin was TFE unit:HFP unit:PPVE unit=92.7:2.7:4.6. Next, fluorination treatment was carried out in the same manner as in Example 1 to obtain a molding material C containing the fluororesin C of Example 3. The fluororesin C was subjected to infrared absorption spectroscopy analysis by the above-mentioned method to determine the number of functional groups. The number of functional groups in the fluororesin C was 10 main chain carbon atoms. ６ The melting point of fluorine-containing resin C was 287.0°C, and the MFR of molding material C was 14.7 g / 10 min.

[0077] [Example 4] After degassing a 0.22 L stainless steel pressure-resistant reactor equipped with anchor blades, 59.2 g of ultrapure water, 19.9 g of PPVE, 0.87 g of methanol, and 8.64 g of a 1.0 mass% AE-3000 solution of IPP were charged into the reactor, and the gas phase was degassed under reduced pressure while the reactor was cooled in an ice bath. While stirring at a rotation speed of 280 rpm using anchor blades, 45.9 g of HFP and 68.8 g of TFE were injected into the reactor, and the liquid phase temperature was then raised to 40 ° C. to initiate suspension polymerization. The pressure inside the reactor was 1.61 MPa. The parameter B in the stirring treatment of Example 4 was 0.70 m ２ / s ３ After the start of polymerization, the polymerization was deemed to be terminated when the internal pressure of the reaction vessel decreased by 0.4 MPa. The polymerization time was 58 minutes. After the polymerization was completed, the internal temperature of the reaction vessel was reduced to 23°C, and purging was performed until the internal pressure of the reaction vessel became atmospheric pressure, followed by thorough replacement with nitrogen.

[0078] The reaction vessel was opened, and the obtained slurry was filtered through a filter to separate the polymerization medium. Then, the white wet powder was washed with ultrapure water and vacuum dried at 80 ° C for 12 hours to obtain 26.5 g of a molding material containing a white fluorine-containing resin. The content (mass%) of each unit in the obtained fluorine-containing resin was TFE unit: HFP unit: PPVE unit = 93.1: 3.0: 3.9. Next, fluorination treatment was carried out in the same manner as in Example 1 to obtain a molding material D containing the fluorine-containing resin D of Example 4. The fluorine-containing resin D was subjected to infrared absorption spectroscopy analysis by the above method to determine the number of functional groups. The number of functional groups of the fluorine-containing resin D was 10 main chain carbon atoms. ６The melting point of fluororesin D was 291.0°C, and the MFR of molding material D was 14.5 g / 10 min.

[0079] The molding material prepared in each example was subjected to the above-mentioned measurement and evaluation test.Table 2 shows the composition of the fluorine-containing resin in each example, the measurement results of the fluorine-containing resin and molding material, and the evaluation test results of the molding material.In the table, the "TFE unit" column, "HFP unit" column and "PPVE unit" column of "composition ratio (mass%)" respectively show the content (unit: mass%) of TFE unit, the content (unit: mass%) of HFP unit and the content (unit: mass%) of PPVE unit relative to the total units contained in the fluorine-containing resin.

[0080]

[0081] As shown in Table 2, the molding material of the present invention has a parameter A of 0.005 (h －１ ) and the MFR was 10.0 to 30.0 g / 10 min, it was confirmed that the viscosity reduction rate at the initial stage of heating was faster (Examples 1 to 4).

[0082] The entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2024-115651 filed on July 19, 2024 are hereby incorporated by reference as the disclosure of the present invention.

Claims

1. A molding material containing a fluororesin containing units based on tetrafluoroethylene, units based on perfluoro(alkyl vinyl ether), and units based on hexafluoropropylene, wherein the content of the units based on perfluoro(alkyl vinyl ether) is 1.0 to 5.0% by mass based on the total units of the fluororesin, the content of the units based on hexafluoropropylene is 2.4 to 4.8% by mass based on the total units of the fluororesin, the melt flow rate of the molding material measured at a temperature of 372°C in accordance with ASTM D1238 is 10.0 to 30.0 g / 10 min, and the total number of functional groups possessed by the fluororesin is 10 to 150% by mass based on the total number of main chain carbon atoms of the fluororesin. ６ The parameter A defined by the following formula (1) is 0.005 (h －１ A molding material characterized in that A={F(t １ ) / t １ } / F(t ２ ) F(t １ ) is the amount of fluoride ion elution (μg) obtained by immersing 3 g of the molding material in 10 mL of a mixed liquid containing methanol and water in a volume ratio of 1:1 at 85°C for 24 hours, recovering the mixed liquid, and measuring the fluoride ion concentration contained in the mixed liquid, and F(t ２ ) is the amount of fluoride ion elution (μg) obtained by immersing 3 g of the molding material in 10 mL of the mixed liquid at 85° C. for 336 hours, recovering the mixed liquid, and measuring the fluoride ion concentration contained in the mixed liquid; and t １ is 24(h).

2. The molding material of claim 1, wherein the perfluoro(alkyl vinyl ether) is perfluoro(propyl vinyl ether).

3. The molding material according to claim 1 or 2, wherein the content of units based on the perfluoro(alkyl vinyl ether) is 4.6 to 5.0 mass% based on the total units of the fluorine-containing resin.

4. The molding material according to claim 1 or 2, wherein the content of units based on hexafluoropropylene is 2.6 to 3.0 mass% based on the total units of the fluororesin.

5. The molding material according to claim 1 or 2, wherein the content of units based on tetrafluoroethylene is 90.2 to 96.6 mass % based on the total units of the fluorine-containing resin.

6. The molding material according to claim 1 or 2, wherein the melt flow rate of the molding material is 11.0 to 19.0 g / 10 min.

7. The total number of functional groups possessed by the fluororesin is 10 or less than the number of carbon atoms in the main chain of the fluororesin. ６ The molding material according to claim 1 or 2, wherein the number of particles per particle is less than 20.

8. The molding material according to claim 1 or 2, wherein the viscosity reduction rate at the initial stage of heating, as defined by the conditions of the following formula (2), is 9,000 Pa or more. Formula (2) Viscosity reduction rate at the initial stage of heating = |(η ＊ ３０ -η ＊ ６ ) / (30-6) | η ＊ ６ is the complex viscosity 6 seconds after the start of measurement when the molding material is measured using a closed biconical die of a rubber processability tester under the conditions of vibration mode, frequency 50 cpm, strain 0.5 deg, and temperature 310°C, and η ＊ ３０ is the complex viscosity 30 seconds after the start of measurement when the molding material is measured using a closed biconical die of a rubber processability tester under the conditions of vibration mode, frequency 50 cpm, strain 0.5 deg, and temperature 310°C.

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