Solid composition, extrusion molded article, blow molded article, transfer molded article, press molded article, injection molded article, coated electric wire, and molded article

Abstract

The present invention addresses the problems of providing a solid composition capable of forming a molded article excellent in high temperature tensile elongation, electric insulation, heat resistance, flexural modulus, high temperature tensile elastic modulus, low coloration and low foamability, and of providing an extrusion molded article, a blow molded article, a transfer molded article, a press molded article, an injection molded article, a coated electric wire, and a molded article.　The solid composition according to the present invention contains: a copolymer containing a unit based on tetrafluoroethylene and a unit based on perfluoro(alkyl vinyl ether); and a metal element. The content of the unit based on perfluoro(alkyl vinyl ether) is 2.9-4.0 mass% relative to all units contained in the copolymer; the content of the unit based on tetrafluoroethylene is 96.0-97.1 mass% relative to all units contained in the copolymer, the solid composition has a melt flow rate measured under the condition of a temperature of 372°C in accordance with ASTM D1238 of 1.4-2.9 g / 10 min; the copolymer has a melting point of 298°C or higher; the total number of specific functional groups possessed by the copolymer is 150 or less per 106 carbon atoms of the copolymer; and the content of the metal element is 0.0100-2.0000 ppm by mass relative to the total mass of the solid composition.

Description

Solid compositions, extrusion molded articles, blow molded articles, transfer molded articles, press molded articles, injection molded articles, coated electric wires, and molded articles

[0001] The present invention relates to solid compositions, extrusions, blow molded articles, transfer molded articles, press molded articles, injection molded articles, coated wires and molded articles.

[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 copolymer containing tetrafluoroethylene units and perfluoro(propyl vinyl ether) units, in which the content of perfluoro(propyl vinyl ether) units is 2.0 to 2.8 mass% based on the total monomer units, and which has a melt flow rate of 23 to 30 g / 10 min.

[0003] Japanese Patent Application Laid-Open No. 2022-058290

[0004] When PFA is used as a constituent material of a molded article, the molded article is required to have excellent properties such as mechanical strength, heat resistance, electrical insulation, low coloration, low foaming, etc. When the present inventors evaluated molded articles formed using the PFA described in Patent Document 1, they found that there was room for improvement in mechanical strength (particularly high-temperature tensile elongation, flexural modulus, and high-temperature tensile modulus), electrical insulation, heat resistance, low coloration, and low foaming.

[0005] Therefore, an object of the present invention is to provide a solid composition capable of forming a molded article having excellent high-temperature tensile elongation, electrical insulation, heat resistance, flexural modulus, high-temperature tensile modulus, low colorability, and low foaming property. Another object of the present invention is to provide an extrusion-molded article, a blow-molded article, a transfer-molded article, a press-molded article, an injection-molded article, a coated electric wire, and a molded article.

[0006] As a result of intensive research into the above-mentioned problems, the present inventors have found that by using a solid composition containing a copolymer containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether), and a metal element, wherein the contents of each unit are within predetermined ranges, the melt flow rate measured under predetermined conditions is 1.4 to 2.9 g / 10 min, the melting point of the copolymer is 298°C or higher, the total number of specific functional groups possessed by the copolymer is within a predetermined range, and the content of the metal element contained in the solid composition is within a predetermined range, it is possible to form a molded article that is excellent in high-temperature tensile elongation, electrical insulation, heat resistance, flexural modulus, high-temperature tensile modulus, low colorability, and low foaming property, and have arrived at the present invention.

[0007] That is, the inventors have found that the above-mentioned problems can be solved by the following constitution: [1] A solid composition containing a copolymer containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether), and a metal element, wherein the content of the units based on perfluoro(alkyl vinyl ether) in the copolymer is 2.9 to 4.0 mass% based on all units contained in the copolymer, the content of the units based on tetrafluoroethylene is 96.0 to 97.1 mass% based on all units contained in the copolymer, the melt flow rate of the solid composition measured at a temperature of 372°C in accordance with ASTM D1238 is 1.4 to 2.9 g / 10 min, the melting point of the copolymer is 298°C or higher, and -CF=CF contained in the copolymer ２ , -CF ２ H, -COF, -COOH, -COOCH ３ , -CONH ２ and -CH ２ The total number of OH functional groups is 10 ６

[0013]

[0014] A solid composition, characterized in that the number of particles per particle is 150 or less, and the content of the metal element is 0.0100 to 2.0000 ppm by mass relative to the total mass of the solid composition. [2] The solid composition according to [1], wherein the perfluoro(alkyl vinyl ether) is perfluoro(propyl vinyl ether). [3] An extrusion-molded article obtained by extrusion-molding the solid composition according to [1] or [2]. [4] A blow-molded article obtained by blow-molding the solid composition according to [1] or [2]. [5] A transfer-molded article obtained by transfer-molding the solid composition according to [1] or [2]. [6] A press-molded article obtained by press-molding the solid composition according to [1] or [2]. [7] An injection-molded article obtained by injection-molding the solid composition according to [1] or [2]. [8] A coated electric wire, comprising a conductor and a coating layer disposed on the surface of the conductor and obtained by molding the solid composition according to [1] or [2]. [9] A molded article obtained by molding the solid composition according to [1] or [2], wherein the molded article is a piping member, an electric wire covering material, a tube, a film, or a compressed member.

[0008] The present invention provides a solid composition capable of forming a molded article having excellent high-temperature tensile elongation, electrical insulation, heat resistance, flexural modulus, high-temperature tensile modulus, low colorability, and low foaming property. The present invention also provides an extrusion-molded article, a blow-molded article, a transfer-molded article, a press-molded article, an injection-molded article, a coated electric wire, and a molded article.

[0009] 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.

[0010] The term "unit" refers collectively to an atomic group derived from one molecule of the above-mentioned monomer, which is formed directly by polymerizing the monomer, and an atomic group obtained by chemically converting a part of the above-mentioned atomic group. In the following, in some cases, a unit derived from an individual monomer will be referred to by the name of the monomer followed by "unit." A "TFE unit" is a unit based on tetrafluoroethylene contained in the copolymer. A "PAVE unit" is a unit based on perfluoro(alkyl vinyl ether) contained in the copolymer, and a "PPVE unit" is a unit based on perfluoro(propyl vinyl ether) contained in the copolymer. A "specific functional group" refers to a group such as -CF=CF ２ , -CF ２ H, -COF, -COOH, -COOCH ３ , -CONH ２ and -CH ２ The term "functional group number" refers to the total number of specific functional groups contained in the copolymer, unless otherwise specified.

[0011] [Solid Composition] The solid composition of the present invention (hereinafter also referred to as "the present solid composition") comprises a copolymer (hereinafter also referred to as "the present copolymer") containing TFE units and PAVE units within a predetermined range, respectively, and a predetermined amount of a metal element. The present copolymer also contains a predetermined amount of a specific functional group. The present solid composition also has a melt flow rate (hereinafter also referred to as "MFR") measured at 372°C according to ASTM D1238 within a predetermined range. As used herein, "solid composition" refers to a composition that is solid at 25°C. The content of the present copolymer is preferably 70% by mass or more but less than 100% by mass, more preferably 90% by mass or more but less than 100% by mass, and even more preferably 99% by mass or more but less than 100% by mass, based on the total mass of the present solid composition. When the content of the present copolymer is within the above range, a molded article formed from the present solid composition is likely to have excellent high-temperature tensile elongation, electrical insulation, heat resistance, flexural modulus, high-temperature tensile modulus, low colorability, and low foaming properties.

[0012] By using this solid composition, molded articles having excellent high-temperature tensile elongation, electrical insulation, heat resistance, flexural modulus, high-temperature tensile modulus, low colorability, and low foaming can be formed. While the details of the reasons for this are not yet clear, it is presumed that the following reasons are involved. Specifically, it is presumed that a PAVE unit content of 2.9% by mass or more, relative to the total units contained in the copolymer, results in high flexibility and easy elongation, thereby improving the high-temperature tensile modulus of the molded article. It is presumed that a PAVE unit content of 4.0% by mass or less, relative to the total units contained in the copolymer, results in high crystallinity and resistance to deformation, thereby improving the high-temperature tensile elongation of the molded article. It is presumed that an MFR of 1.4 g / 10 min or more improves the fluidity of the solid composition when melted, thereby providing excellent moldability of the solid composition and improving the flexural modulus of the molded article. It is presumed that an MFR of 2.9 g / 10 min or less reduces the number of terminals that serve as the initiation point for breakdown in the solid composition, thereby reducing the likelihood of dielectric breakdown due to cracking and improving electrical insulation. In addition, in the present solid composition, the number of functional groups, which is the total number of specific functional groups possessed by the copolymer, is 10 or less than the number of carbon atoms of the copolymer. ６ It is presumed that the heat resistance of the molded article is improved because decomposition from the terminal functional groups is suppressed by having the number of terminal groups be 150 or less. Furthermore, it is presumed that the heat resistance of the molded article is improved because the metal element content of the solid composition is 0.0100 ppm by mass or more, relative to the total mass of the solid composition, causes a metal-mediated crosslinking reaction within the solid composition, improving heat resistance, and therefore the molded article exhibits low foaming properties. Furthermore, it is presumed that the metal element content of the solid composition is 2.0000 ppm by mass or less, relative to the total mass of the solid composition, facilitates uniform dispersion of the metal within the solid composition, and therefore the molded article exhibits low coloration. Furthermore, the melting point of the copolymer is 298°C or higher, and therefore it is not intended to be a so-called elastomer. An elastomer is a copolymer without a melting point. Thus, it is presumed that by satisfying each requirement, a molded article excellent in high-temperature tensile elongation, electrical insulation, heat resistance, flexural modulus, high-temperature tensile modulus, low coloration, and low foaming properties was obtained.

[0013] <Copolymer> The present copolymer contains TFE units based on TFE and PAVE units based on PAVE.

[0014] As the PAVE, a monomer represented by formula 1 is preferred: CF ２ ═CF—O—Rf １ (1) In formula 1, 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 2.9 to 4.0% by mass, based on all units contained in the copolymer. From the viewpoint of achieving a well-balanced and excellent high-temperature tensile elongation and high-temperature tensile modulus of elasticity in the molded article, the content of PAVE units is preferably 3.0 to 3.8% by mass, based on all units contained in the copolymer, and more preferably 3.1 to 3.8% by mass. From the viewpoint of achieving a balanced high-temperature tensile elongation and tensile modulus and an even better high-temperature tensile elongation, the content of PAVE units is preferably 2.9 to 3.3% by mass, based on all units contained in the copolymer, and more preferably 3.0 to 3.3% by mass. From the viewpoint of achieving a balanced high-temperature tensile elongation and tensile modulus and an even better high-temperature tensile modulus, the content of PAVE units is preferably 3.5 to 4.0% by mass, based on all units contained in the copolymer, and more preferably 3.5 to 3.8% by mass. The copolymer may contain two or more types of PAVE units. When the copolymer 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 TFE units is 96.0 to 97.1% by mass relative to all units contained in the copolymer. From the viewpoint of achieving a balanced and excellent high-temperature tensile elongation and tensile modulus of elasticity in the molded article, the content of TFE units is preferably 96.2 to 97.0% by mass, more preferably 96.2 to 96.9% by mass, relative to all units contained in the copolymer. From the viewpoint of achieving a balanced and even better high-temperature tensile elongation and tensile modulus of elasticity, the content of TFE units is preferably 96.0 to 96.5% by mass, more preferably 96.2 to 96.5% by mass, relative to all units contained in the copolymer. From the viewpoint of achieving a balanced and even better high-temperature tensile elongation and tensile modulus of elasticity, the content of TFE units is preferably 96.7 to 97.1% by mass, more preferably 96.7 to 96.9% by mass, relative to all units contained in the copolymer.

[0018] In addition to the TFE unit and the PAVE unit, the copolymer may contain units based on other monomers copolymerizable with TFE and PAVE. Examples of such other monomers include ethylene, vinylidene fluoride (VdF), hexafluoropropylene (HFP), 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. ２ =CF-OCH ２ -Rf ２ (wherein, Rf ２ represents a perfluoroalkyl group having 1 to 5 carbon atoms. When the present copolymer contains units based on other monomers, the content of the units based on other monomers is 0.8% by mass or less, and preferably 0.1 to 0.4% by mass, based on the total units contained in the present copolymer.

[0019] In order to obtain a more excellent abrasion resistance during repeated use, it is particularly preferred that the copolymer does not contain units derived from the other monomers and contains only TFE units and PAVE units. In this case, the total content of TFE units and PAVE units is 100.0% by mass based on the total units contained in the copolymer.

[0020] The contents of the TFE units, the PAVE units and the units based on other monomers in the copolymer are １９ 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.

[0021] (Number of Functional Groups) The present copolymer has a total number of specific functional groups that is equal to or greater than 10 carbon atoms of the present copolymer. ６ Each piece contains 150 or less pieces.

[0022] The specific functional groups are functional groups present at the main chain end or side chain end of the copolymer, and functional groups present in the main chain or side chain, and the number of functional groups is the total number of specific functional groups. The specific functional groups are introduced into the copolymer by, for example, a chain transfer agent or a polymerization initiator used in the production of the copolymer. More specifically, when an alcohol is used as a chain transfer agent or when -CH ２ When a peroxide having an OH structure is used, the main chain terminal of the copolymer is formed with -CH ２ OH is introduced. Furthermore, by polymerizing a monomer having a functional group, the functional group is introduced into the side chain terminal of the copolymer. Furthermore, when the number of functional groups in a copolymer having a specific functional group exceeds a predetermined range, the number of functional groups can be reduced by fluorinating the copolymer. The number of functional groups in the copolymer can be adjusted by changing the conditions of the fluorination treatment (e.g., treatment time) described below.

[0023] The number of functional groups of the copolymer is set to 10, since this allows the formation of a molded product with better heat resistance. ６ The number per unit is preferably 100 or less, more preferably 50 or less, even more preferably 10 or less, still more preferably 6 or less, and particularly preferably less than 6.

[0024] Infrared spectroscopy can be used to identify the type of functional group in a copolymer and measure the number of functional groups. Specifically, the number of functional groups is measured by the following method. First, the copolymer is molded by hot pressing at 330°C to produce a film with a thickness of 0.30 to 0.35 mm. This film is analyzed by Fourier transform infrared spectroscopy to obtain an infrared absorption spectrum of the copolymer. Separately, an infrared absorption spectrum (base spectrum) of a copolymer that is completely fluorinated and does not contain any specific functional groups is obtained, and a difference spectrum between the infrared absorption spectrum of the copolymer and the base spectrum is obtained. From the absorption peaks of the specific functional groups that appear in this difference spectrum, the number of carbon atoms in the copolymer is calculated according to the following formula A: ６ The number of functional groups per molecule, N, is calculated.

[0025] N = I x K / t (A) I: absorbance K: correction coefficient t: film thickness (mm)

[0026] The absorption frequency, molar absorption coefficient, and correction factor for a specific functional group are shown in Table 1. The molar absorption coefficient for a specific functional group is determined from FT-IR measurement data of a low molecular weight model compound.

[0027]

[0028] In the copolymer, -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: 1883 cm －１ The number of functional groups determined from the absorption peak of -CH２ Absorption frequency due to COF: 1840 cm －１ The number of functional groups is the sum of the number of functional groups determined from the absorption peaks of the compounds.

[0029] (Melting Point) The melting point of the copolymer is 298°C or higher, and is preferably 299 to 310°C, more preferably 300 to 309°C, in order to obtain a molded article with superior mechanical strength. A specific example of a method for adjusting the melting point of the copolymer within the above range is to lower the polymerization temperature during production of the copolymer. The melting point of the copolymer is the temperature corresponding to the endothermic peak when the copolymer is heated at a rate of 10°C / min in an air atmosphere using a differential scanning calorimeter. The melting point of the copolymer may also be determined by measuring the melting point of the solid composition using the above method.

[0030] The content of the present copolymer 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, based on the total mass of the present solid composition. When the content of the present copolymer is within the above range, the composition is likely to become a solid composition.

[0031] <Metal Element> The present solid composition contains a metal element. The metal element is not particularly limited as long as it is a metal element that can be measured by inductively coupled plasma mass spectrometry (ICP-MS) described below, and examples thereof include 29 types of metal elements (Fe, Na, K, Li, Be, Mg, Al, Ca, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Rb, Sr, Zr, Mo, Ag, Cd, In, Sn, Cs, Ba, Pb, and Bi).

[0032] The content of the metal element is 0.0100 to 2.0000 ppm by mass, relative to the total mass of the solid composition. When the content of the metal element is 2.0000 ppm by mass or less, relative to the total mass of the solid composition, a molded article that is excellent in not only low coloration but also low foaming properties can be formed. From the viewpoint of obtaining a molded article that is excellent in a well-balanced manner in low foaming properties and low coloration properties, the content of the metal element is preferably 0.1000 to 1.8000 ppm by mass, more preferably 0.3000 to 1.5000 ppm by mass, relative to the total mass of the solid composition.

[0033] The content of the metal elements can be measured, for example, by ICP-MS as described below. When measuring the 29 metal elements, the solid composition is placed in a platinum crucible and incinerated in a high-temperature electric heating furnace, and then treated with sulfuric acid white smoke to obtain a solution, which is then dissolved in dilute nitric acid. The content of the 29 metal elements (Fe, Na, K, Li, Be, Mg, Al, Ca, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Rb, Sr, Zr, Mo, Ag, Cd, In, Sn, Cs, Ba, Pb, and Bi) measured by the absolute calibration curve method is measured using an inductively coupled plasma mass spectrometer (for example, "ICP-MS 7500cs" (product name, manufactured by Agilent Technologies), etc.), and the obtained measured values ​​are summed to determine the content of the metal elements in the solid composition.

[0034] The metal elements in the present solid composition are derived from, for example, metal elements contained in the materials (monomers, polymerization solvents, etc.) used in the production of the copolymer. Therefore, one method for adjusting the content of metal elements is, for example, using a material with a low metal element content in the production method of the present solid composition described below. As a result of various studies on the production method of the present solid composition, the present inventors have found that, particularly for the polymerization medium (e.g., water) used in copolymerizing TFE and PAVE, it is important to use a polymerization medium (e.g., ultrapure water) with a low metal element content, and that the characteristics of such a polymerization medium significantly affect the metal element content of the solid composition. In addition, the present inventors have found that, in the polymerization of monomers, the metal element content of the resulting solid composition can be reduced by reducing the total content (concentration, mass%) of the monomer (e.g., PAVE) and the polymerization solvent other than water (e.g., methanol) in the polymerization vessel before adding the polymerization initiator.

[0035] <Other Components> The present solid composition may contain other components in addition to those described above. Specific examples of such other components include resins other than the present copolymer, heat stabilizers, antioxidants, colorants, UV absorbers, fillers, crosslinking agents, crosslinking aids, and organic peroxides. When the present solid composition 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 the present copolymer in the present solid composition.

[0036] <Physical Properties of Solid Composition> (Melt Flow Rate) The MFR of the solid composition is 1.4 to 2.9 g / 10 min. The MFR of the solid composition is preferably 1.42 to 2.85 g / 10 min, from the viewpoint of forming a molded article having a well-balanced flexural modulus and electrical insulation properties. The MFR of the solid composition is preferably 1.42 to 2.50 g / 10 min, from the viewpoint of forming a molded article having a well-balanced flexural modulus and electrical insulation properties, particularly excellent electrical insulation properties. The MFR of the solid composition is preferably 2.50 to 2.85 g / 10 min, from the viewpoint of forming a molded article having a well-balanced flexural modulus and electrical insulation properties, particularly excellent flexural modulus properties. A specific example of a method for adjusting the MFR of the solid composition within the above range is a method of adjusting the molecular weight of the copolymer contained in the solid composition. The higher the molecular weight of the copolymer, the lower the MFR. The MFR of a solid composition means the mass of the solid composition that flows out of an orifice having a diameter of 2 mm and a length of 8 mm in 10 minutes, measured under conditions of a temperature of 372°C and a load of 5 kg in accordance with ASTM D1238.

[0037] <Method for Producing Solid Composition> Examples of methods for producing the present solid composition include methods including the step of producing the present copolymer, which will be described later.

[0038] The process for producing this copolymer can be a polymerization reaction process of copolymerizing the above-mentioned monomers (TFE and PAVE).The polymerization method can be any known polymerization method such as bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, etc., and among them, the copolymer is preferably produced by solution polymerization.In the production of this copolymer, in addition to the above-mentioned monomers, a polymerization initiator, a polymerization medium, a chain transfer agent, etc. can be used.

[0039] 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.

[0040] The polymerization medium may be water, an organic solvent, or a mixture of water and an organic solvent. The organic solvent may be a fluorine-based solvent such as perfluorocarbon, hydrofluorocarbon, or hydrofluoroether. Specific examples of the organic solvent include the polymerization mediums exemplified in International Publication No. 2013 / 015202.

[0041] The polymerization medium preferably contains water, and more preferably contains ultrapure water. The content of metal elements contained in the water used as the polymerization medium is preferably 2.0 ppm by mass or less, more preferably 1.0 ppm by mass or less, even more preferably 0.5 ppm by mass or less, and particularly preferably 0.1 ppm by mass or less, relative to the total mass of water, from the viewpoint of facilitating the production of a solid composition with a low content of metal elements. Furthermore, the content of metal elements is preferably 0 ppb by mass or more, relative to the total mass of water. Examples of methods for achieving the above-mentioned metal element content include methods in which the content of metal elements is reduced by filtering the water through various filters. The content of metal elements contained in water can be measured by an absolute calibration curve method using ICP-MS, similar to the method for measuring the content of metal elements in the solid composition described above. Furthermore, the conductivity of the water used as the polymerization medium is preferably 1.00 μS / cm or less, more preferably 0.06 μS / cm or less. The conductivity of water is preferably 0 μS / cm or more. The conductivity of water can be measured by known measurement methods.

[0042] The polymerization medium may be used alone or in combination of two or more. As the polymerization medium, a mixed solvent of water and a fluorine-based solvent is preferred, and a mixed solvent of water and a perfluorocarbon is more preferred. From the standpoints of suspension property and economy, the amount of the fluorine-based solvent used is preferably 10 to 100% by mass relative to the mixed solvent. The amount of the polymerization medium used is preferably 3 times or more, more preferably 5 times or more, by mass ratio relative to the amount of the monomer used. Also, it is preferably 20 times or less, more preferably 17 times or less.

[0043] The chain transfer agent may be selected from the group consisting of alcohols such as methanol, ethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoropropanol, 1,1,1,3,3,3-hexafluoroisopropanol, and 2,2,3,3,3-pentafluoropropanol, hydrocarbons such as n-pentane, n-hexane, and cyclohexane, and CF ２ H ２Preferred 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 alcohols, hydrocarbons, and hydrofluorocarbons is preferred, as they have a higher chain transfer constant and provide high stability to the end groups of the copolymer. At least one selected from the group consisting of alcohols and hydrocarbons is more preferred, and alcohols are even more preferred. Among alcohols, methanol or ethanol is preferred, with methanol being more preferred in terms of 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 amount of monomer used. Also, it is preferably 5 times or less, more preferably 4 times or less.

[0044] The materials used in the production of the copolymer (monomer components, polymerization initiators, emulsifiers, chain transfer agents, pH adjusters, etc.) are preferably compounds with low metal element contents, since it is easy to obtain a solid composition with low metal element contents. In particular, it is more preferable that materials other than the polymerization medium do not contain metal elements.

[0045] 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 25°C or higher, the polymerizability is excellent. When the polymerization temperature is 60°C or lower, the melting point of the copolymer 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.

[0046] When an aqueous dispersion containing the copolymer is obtained by polymerization, the copolymer can be recovered by coagulating the copolymer contained in the aqueous dispersion, washing, and drying. When the copolymer is obtained as a slurry by polymerization, the copolymer can be recovered by removing the slurry from the reaction vessel, washing, and drying. By drying, the copolymer can be recovered in powder form.

[0047] The copolymer obtained by polymerization may be subjected to a fluorination treatment. By the fluorination treatment, the —COOH and —COOCH groups contained in the copolymer are removed. ３ , -CH ２ OH, -COF, -CF=CF ２ , -CONH ２ , and -CF ２ It is possible to reduce the number of specific functional groups consisting of H. As a result, even if the total number of specific functional groups (number of functional groups) of the copolymer exceeds a predetermined range, the number of functional groups of the copolymer can be easily adjusted by the fluorination treatment.

[0048] The fluorination treatment is carried out by contacting the copolymer with a fluorine-containing compound. Examples of the fluorine-containing compound include a fluorine radical source that generates fluorine radicals under 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.

[0049] 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.

[0050] The fluorination treatment is usually carried out at a temperature below the melting point of the copolymer, preferably 20 to 240°C, more preferably 100 to 235°C. The fluorination treatment may be carried out by contacting the copolymer in a molten state with a fluorine-containing compound. As a specific method of the fluorination treatment, for example, a shelf on which pellets of the copolymer are placed is placed in an oven, and the inside of the oven is heated to F ２An example of such a method is to fill a column packed with copolymer pellets with a gas or the above-mentioned mixed gas, and then heat the column for a certain period of time. Another example is to pass a gas or the above-mentioned mixed gas through a flow column packed with copolymer pellets for a certain period of time while heating the column. The treatment time for the fluorination treatment varies appropriately depending on the number of functional groups in the copolymer 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. The present copolymer is preferably produced by obtaining a copolymer by polymerization, and then subjecting the obtained copolymer to the above-mentioned fluorination treatment.

[0051] The method for producing the present solid composition may, if necessary, include a step of melt-kneading the present copolymer produced by the above method with the other components described above by a known method.

[0052] [Molded Article] The molded article of the present invention is obtained by molding the above-described solid composition. Since the molded article of the present invention is molded using the solid composition, it has excellent high-temperature tensile elongation, electrical insulation, heat resistance, flexural modulus, high-temperature tensile modulus, low colorability, and low foaming. Specific examples of molded articles include injection-molded articles obtained by injection molding, extrusion-molded articles obtained by extrusion, blow-molded articles obtained by blow molding, transfer-molded articles obtained by transfer molding, press-molded articles obtained by press molding, rotation-molded articles obtained by rotation-molding, and coating films obtained by electrostatic coating of the solid composition. Press-molded articles obtained by press molding are preferred. Injection-molded articles obtained by injection molding are also preferred because they can be obtained with beautiful appearance without corroding the mold used for molding.

[0053] The molded product of the present invention may take the form of pellets or powder, for example. Pellets of the present solid composition can be molded using conventional methods. Examples of methods for molding pellets include extruding the solid composition 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 copolymer contained in the solid composition and the manufacturing method, but is preferably between the melting point of the copolymer + 20°C and the melting point of the copolymer + 140°C. The melted and extruded solid composition 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 volatile components (degassing treatment). The resulting pellets may also 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.

[0054] Specific examples of the molded article of the present invention 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.

[0055] The present solid composition or the above-mentioned molded product 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.

[0056] In particular, the molded article of the present invention can be suitably used as piping components (e.g., piping, joints, gaskets, and packings), tubes, or films for transporting fluids. The molded article of the present invention 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 formed around the core wire and made of the molded article of the present invention. A coated electric wire having a coating layer made of the molded article of the present invention has excellent electrical properties because the core wire is resistant to corrosion and there is little change in its outer diameter, and is therefore suitably used as a high-frequency transmission cable, a flat cable, a heat-resistant cable, or the like. Such a coated electric wire can be produced, for example, by melt-extrusion molding the present solid composition onto a core wire to form a coating layer.

[0057] The molded article of the present invention 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.

[0058] The present invention will be described in detail below with reference to examples. Examples 1 to 6 are working examples, and Examples 7 to 13 are comparative examples. However, the present invention is not limited to these examples. Various measurement methods and evaluation methods are as follows.

[0059] [Content of Each Unit] The contents (mass%) of TFE units and PAVE units in the copolymer are １９ The molar ratio of each unit was calculated by F-NMR analysis, and the calculated molar ratio was converted into a mass ratio from the chemical structural formula of each unit.

[0060] [MFR (Melt Flow Rate)] For pellets of the solid composition obtained in each example, the mass (g) of the solid composition flowing out of an orifice having a diameter of 2 mm and a length of 8 mm in 10 minutes under conditions of a temperature of 372°C and a load of 5 kg was measured using a melt indexer (manufactured by Techno Seven Co., Ltd.) in accordance with ASTM D1238, and this was taken as the MFR (g / 10 min).

[0061] [Number of Functional Groups] Molded bodies (pellets) of the solid compositions obtained in each example were molded by hot pressing at 330°C to prepare sample films having a thickness of 0.30 to 0.35 mm. The sample films were scanned 40 times using a Fourier transform infrared spectrometer (FT-IR, "Spectrum One", manufactured by PerkinElmer) and analyzed to obtain infrared absorption spectra. Next, the pellets were subjected to a fluorination treatment described below for a long period of time, and base pellets that were completely fluorinated and had no specific functional groups were separately prepared. Base films were prepared from the base pellets in the same manner as above. The base films were analyzed by the above method to obtain infrared absorption spectra (base spectra), and the difference spectrum between the infrared absorption spectrum of the sample film and the base spectrum of the base film was obtained. From the absorption peaks of the specific functional groups appearing in this difference spectrum, the carbon number of the copolymer contained in the sample film according to the above formula A was calculated. ６ The number of functional groups per molecule, N, was calculated.

[0062] [Metal Element Content] The metal element content in the solid composition was measured by the following method: The solid composition was placed in a platinum crucible and incinerated in a high-temperature electric heating furnace, and then treated with sulfuric acid white smoke to obtain a solution, which was then dissolved in dilute nitric acid. The contents of 29 metal elements (Fe, Na, K, Li, Be, Mg, Al, Ca, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Rb, Sr, Zr, Mo, Ag, Cd, In, Sn, Cs, Ba, Pb, and Bi) were measured using an inductively coupled plasma mass spectrometer (ICP-MS 7500cs (product name), manufactured by Agilent Technologies) by the absolute calibration curve method, and the measured contents were added together to determine the metal element content in the solid composition. The contents of metal elements in ultrapure water were determined by measuring the contents of the 29 metal elements in the ultrapure water by the absolute calibration curve method using an inductively coupled plasma mass spectrometer (ICP-MS 7500cs (product name), manufactured by Agilent Technologies) in the same manner as in the above-described measurement method, and then adding up the measured contents.

[0063] [Melting Point] The melting point (°C) of the copolymer was determined from the endothermic peak observed when a molded body (pellet) of the solid composition obtained in each example was heated to 300°C at a rate of 10°C / min in an air atmosphere using a differential scanning calorimeter (trade name "DSC7020", manufactured by Hitachi High-Tech Science Corporation).

[0064] [Evaluation Test] <MFR Change Rate at 350°C (Heat Resistance)> Pellets of the solid composition obtained in each example were placed in a glass container and heated in an oven at 350°C for 60 minutes. The MFR of the pellets after heating was measured, and the MFR change rate ΔMFR (%) after heating was calculated using the following formula: ΔMFR = M1 / M2 × 100 M1: MFR of pellet before heating M2: MFR of pellet after heating The heat resistance of each solid composition was evaluated based on the calculated MFR change rate ΔMFR according to the following evaluation criteria: (Evaluation Criteria for Heat Resistance) ○ (Good): MFR change rate ΔMFR is more than 90%. × (Unacceptable): MFR change rate ΔMFR is less than 90%.

[0065] <Watch Glass Test (Foaming)> Pellets (2 g) of the solid composition obtained in each example were placed on a watch glass and heated in an oven at 350°C for 60 minutes. After heating, the pellets were visually inspected for holes and depressions present on their surfaces as traces of foaming. The ratio of the total area of ​​the holes and depressions to the total surface area of ​​the pellet was then calculated to determine the foaming area ratio. The foaming property of each solid composition was evaluated based on the calculated foaming area ratio according to the following evaluation criteria. (Foaming Property Evaluation Criteria) ○ (Good): No foaming, or the ratio of the total foaming area to the total surface area was less than 50%. △ (Acceptable): The ratio of the total foaming area to the total surface area was 50% or more but less than 90%. × (Unacceptable): The ratio of the total foaming area to the total surface area was 90% or more.

[0066] <Film Forming> The solid composition obtained in each example was press-molded at 340°C to obtain a film having a thickness of 1 mm, a film having a thickness of 3 mm, and a film having a thickness of 200 μm. The press molding was performed using a heated press ("SA-301" manufactured by Tester Sangyo Co., Ltd.). The obtained films were subjected to the following evaluation tests.

[0067] <Tensile Elongation at 250°C> Dumbbell-shaped test pieces as specified in ASTM-D638 Type V were cut out from the obtained 1 mm thick film. The obtained test pieces were measured for tensile elongation (unit: %) by pulling them at a pulling rate of 50 mm / min in an environment of 250±2°C using a Strograph (manufactured by Toyo Seiki Seisaku-sho, Ltd.) with the distance between the gripping jigs set to 35 mm. From the measured tensile elongation value, the high-temperature tensile elongation at 250°C of each test piece was evaluated based on the following evaluation criteria. (Evaluation Criteria for Tensile Elongation) ○ (Good): Tensile elongation of 600% or more. × (Unacceptable): Tensile elongation of less than 600%.

[0068] <Electrical Insulation> The dielectric breakdown voltage of the obtained 3 mm thick film was measured according to a method in accordance with ASTM D149. Based on the measured dielectric breakdown voltage, the electrical insulation of each test piece was evaluated based on the following evaluation criteria. (Evaluation criteria for electrical insulation) ○ (Good): Dielectric breakdown voltage of 74.0 kV or more. × (Unacceptable): Dielectric breakdown voltage of less than 74.0 kV.

[0069] <Flexural Modulus at 50°C> Each solid composition was press-molded to prepare a test piece having a width of 2.5 mm, a length of 5.8 mm, and a thickness of 3.2 mm. The flexural modulus of the obtained test piece was measured in an environment of 50°C using a method in accordance with ASTM D790. The flexural modulus of each solid composition was evaluated based on the measured flexural modulus value and the following evaluation criteria. (Evaluation criteria for flexural modulus) ○ (Good): Flexural modulus of 400 MPa or more. × (Unacceptable): Flexural modulus of less than 400 MPa.

[0070] <Tensile Modulus at 100°C> Each solid composition was press-molded to prepare a test piece having a width of 2.5 mm, a length of 5.8 mm, and a thickness of 3.2 mm. The tensile modulus of the obtained test piece was measured in an environment of 100°C using a method in accordance with ASTM D790. From the measured tensile modulus, the high-temperature tensile modulus of each solid composition was evaluated based on the following evaluation criteria: ∘ (Good): Tensile modulus of 110 MPa or more; × (Fail): Tensile modulus of less than 110 MPa.

[0071] <Colorability of Molded Article> The obtained film having a thickness of 3 mm was visually observed, and the colorability of the molded article was evaluated based on the observation results in accordance with the following evaluation criteria. (Evaluation criteria for colorability) ∘ (Good): No coloring such as yellowing was visually observed. × (Poor): Coloring such as yellowing was visually observed.

[0072] <Preparation of Solid Composition Containing Copolymer> In each example, a solid composition containing a copolymer was prepared by the following method.

[0073] [Example 1] A polymerization vessel equipped with a stirrer was degassed and then CF ３ CH ２ OCF ２ CF ２H (AE-3000: product name, manufactured by AGC) 899 g, ultrapure water 271 g, CF ２ = CFO (CF ２ ) ３ 56.3 g of F(PPVE) and 11.5 g of methanol were charged into the polymerization vessel. The temperature inside the polymerization vessel was then raised to 50°C (polymerization temperature), and 181 g of tetrafluoroethylene (TFE) was further charged, and the pressure inside the polymerization vessel was increased to 1.28 MPa (gauge pressure). 2 mL of a 0.06 mass% AE-3000 solution of heptafluorobutyroyl peroxide was charged as a polymerization initiator solution, polymerization was initiated, and the polymerization initiator solution was subsequently continuously added. Furthermore, TFE was continuously charged so that the pressure during polymerization was maintained equal to the pressure at the start of polymerization. 260 minutes after the start of polymerization, 20 mL of the polymerization initiator solution was added, and at this point 160 g of TFE was charged, the polymerization vessel was cooled, and the polymerization vessel was purged to recover unreacted TFE. The conductivity of the ultrapure water used in the polymerization reaction was 0.06 μS / cm. Furthermore, as a result of measurement by the above-mentioned method using ICP-MS, the content of metal elements contained in the ultrapure water used in the polymerization reaction was 0.1 mass ppm or less relative to the total mass of the ultrapure water.

[0074] The resulting copolymer slurry was filtered to separate the polymerization medium, and then dried at 150° C. for 15 hours to obtain Copolymer 1.

[0075] A synchronous twin-screw extruder kneader equipped with a screw having two kneading sections was prepared. Copolymer 1 was introduced into the feeder hopper of the twin-screw extruder kneader, and kneaded while being sucked through the vent with a vacuum pump under conditions of a cylinder temperature of 380°C and a screw rotation speed of 100 rpm. The strands discharged from the vent were slowly cooled and cut with a pelletizer to produce cylindrical untreated pellets 1 having a length of 5 mm or less and a length-to-diameter ratio (length / diameter) of 0.5 or more but less than 1.5.

[0076] Next, the untreated pellets 1 were subjected to a fluorination treatment in the following manner. The untreated pellets 1 were placed in a special tray and placed in a box-type reaction oven, and the oven was then sealed. After evacuating the oven, F ２The 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 the reaction was carried out for 12 hours 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. ２ / N ２ Mixed gas is sufficiently N ２ The gas was replaced with a gas to obtain pellets 1 of solid composition 1 containing copolymer 1. In each example, the composition of the non-fluorination-treated copolymer and the composition of the fluorination-treated copolymer were the same.

[0077] [Example 2] Copolymer 2 of Example 2 was obtained in the same manner as in Example 1, except that the amount of PPVE and the amount of methanol initially charged into the polymerization vessel were changed to 76.8 g and 9.5 g, respectively. The polymerization time was 280 minutes. Subsequently, untreated pellets 2 of copolymer 2 were prepared in the same manner as in Example 1, and the untreated pellets 2 were subjected to a fluorination treatment to prepare pellets 2 of solid composition 2 containing copolymer 2.

[0078] [Example 3] Copolymer 3 of Example 3 was obtained in the same manner as in Example 1, except that the amount of PPVE and the amount of methanol initially charged into the polymerization vessel were changed to 66.4 g and 12.3 g, respectively, and the total amount of the polymerization initiator solution continuously charged was changed to 22 mL. The polymerization time was 290 minutes. Subsequently, untreated pellets 3 of copolymer 3 were prepared in the same manner as in Example 1, and the untreated pellets 3 were subjected to a fluorination treatment to prepare pellets 3 of solid composition 3 containing copolymer 3.

[0079] [Example 4] Copolymer 4 of Example 4 was obtained in the same manner as in Example 1, except that the amount of methanol initially charged into the polymerization vessel was changed to 15.2 g and the total amount of the polymerization initiator solution continuously charged was changed to 19 mL. The polymerization time was 360 minutes. Subsequently, untreated pellets 4 of copolymer 4 were prepared in the same manner as in Example 1, and the untreated pellets 4 were subjected to a fluorination treatment to prepare pellets 4 of solid composition 4 containing copolymer 4.

[0080] [Example 5] Copolymer 5 of Example 5 was obtained in the same manner as in Example 1, except that the amount of PPVE and the amount of methanol initially charged into the polymerization vessel were changed to 66.4 g and 14.3 g, respectively, and the total amount of the polymerization initiator solution continuously charged was changed to 21 mL. The polymerization time was 350 minutes. Subsequently, untreated pellets 5 of copolymer 5 were prepared in the same manner as in Example 1, and the untreated pellets 5 were subjected to a fluorination treatment to prepare pellets 5 of solid composition 5 containing copolymer 5.

[0081] [Example 6] Copolymer 6 of Example 6 was obtained in the same manner as in Example 1, except that the amount of PPVE and the amount of methanol initially charged into the polymerization vessel were changed to 76.8 g and 13.1 g, respectively, and the amount of polymerization initiator solution continuously charged was changed to 24 mL. The polymerization time was 325 minutes. Subsequently, untreated pellets 6 of copolymer 6 were prepared in the same manner as in Example 1, and the untreated pellets 6 were subjected to a fluorination treatment to prepare pellets 6 of solid composition 6 containing copolymer 6.

[0082] [Example 7] Copolymer 7 of Example 7 was obtained in the same manner as in Example 1, except that the amount of PPVE and the amount of methanol initially charged into the polymerization vessel were changed to 66.4 g and 4.5 g, respectively, and the amount of polymerization initiator solution continuously charged was changed to 9 mL. The polymerization time was 265 minutes. Subsequently, untreated pellets 7 of copolymer 7 were prepared in the same manner as in Example 1, and the untreated pellets 7 were subjected to a fluorination treatment to prepare pellets 7 of solid composition 7 containing copolymer 7.

[0083] [Example 8] Copolymer 8 of Example 8 was obtained in the same manner as in Example 1, except that the amount of PPVE and the amount of methanol initially charged into the polymerization vessel were changed to 51.3 g and 15.2 g, respectively, and the amount of polymerization initiator solution continuously charged was changed to 22 mL. The polymerization time was 275 minutes. Subsequently, untreated pellets 8 of copolymer 8 were prepared in the same manner as in Example 1, and the untreated pellets 8 were subjected to a fluorination treatment to prepare pellets 8 of solid composition 8 containing copolymer 8.

[0084] [Example 9] Copolymer 9 of Example 9 was obtained in the same manner as in Example 1, except that the amount of PPVE and the amount of methanol initially charged into the polymerization vessel were changed to 84.7 g and 11.7 g, respectively, and the amount of polymerization initiator solution continuously charged was changed to 21 mL. The polymerization time was 365 minutes. Subsequently, untreated pellets 9 of copolymer 9 were prepared in the same manner as in Example 1, and the untreated pellets 9 were subjected to a fluorination treatment to prepare pellets 9 of solid composition 9 containing copolymer 9.

[0085] [Example 10] Copolymer 10 of Example 10 was obtained in the same manner as in Example 1, except that the amount of PPVE and the amount of methanol initially charged into the polymerization vessel were changed to 66.4 g and 16.3 g, respectively, and the amount of polymerization initiator solution continuously charged was changed to 31 mL. The polymerization time was 270 minutes. Subsequently, untreated pellets 10 of copolymer 10 were prepared in the same manner as in Example 1, and the untreated pellets 10 were subjected to a fluorination treatment to prepare pellets 10 of solid composition 10 containing copolymer 10.

[0086] [Example 11] Copolymer 11 of Example 11 was obtained in the same manner as in Example 1, except that the amount of PPVE and the amount of methanol initially charged into the polymerization vessel were changed to 66.4 g and 12.2 g, respectively, and the amount of polymerization initiator solution continuously charged was changed to 21 mL. The polymerization time was 300 minutes. Subsequently, untreated pellets 16 of copolymer 11 were prepared in the same manner as in Example 1, and again F ２ / N ２ Untreated pellets 11 were subjected to a fluorination treatment in the same manner as in Example 1, except that the reaction time after the introduction of the mixed gas was changed to 0.3 hours, to prepare pellets 11 of solid composition 11 containing copolymer 11.

[0087] [Example 12] Copolymer 12 was obtained in the same manner as in Example 1, except that the ultrapure water initially charged into the polymerization vessel was changed to water with a conductivity of 3.68 μS / cm, the amount of PPVE was changed to 76.8 g, the amount of methanol was changed to 13.1 g, and the amount of polymerization initiator solution continuously charged was changed to 25 mL. The polymerization time was 320 minutes. Subsequently, untreated pellets 12 of copolymer 12 were prepared in the same manner as in Example 1, and the untreated pellets 12 were subjected to a fluorination treatment to prepare pellets 12 of a solid composition 12 containing copolymer 12.

[0088] [Example 13] Copolymer 13 was obtained in the same manner as in Example 1, except that the amount of PPVE was changed to 76.8 g, the amount of methanol to 13.1 g, and the amount of polymerization initiator solution continuously charged to 25 mL. The polymerization time was 320 minutes. After removing the solvent and ultrapure water from copolymer 13, the filtrate was immersed in ultrapure water with stirring for 48 hours, and then the ultrapure water was removed again by filtration to obtain copolymer 13. Subsequently, untreated pellets 13 of copolymer 13 were prepared in the same manner as in Example 1, and the untreated pellets 13 were subjected to a fluorination treatment to prepare pellets 13 of solid composition 13 containing copolymer 13. The pellets 13 were immersed in ultrapure water (electrical conductivity at 25°C: 0.06 μS / cm) and stirred for 48 hours.

[0089] The above measurements and evaluation tests were carried out on the solid compositions prepared in each example. Table 2 shows the composition of the copolymer in each example, the measurement results of the copolymer and the solid composition, and the evaluation test results of the solid composition. In the table, the "(mass%)" and "(mol%)" columns of "PPVE unit" indicate the content (unit: mass%) and content (unit: mol%) of PPVE unit relative to the total units contained in the copolymer, respectively. The "(mass%)" and "(mol%)" columns of "TFE unit" indicate the content (unit: mass%) and content (unit: mol%) of TFE unit relative to the total units contained in the copolymer, respectively. The "Metal content (mass ppm)" column of "Solid composition" indicates the (total) content of metal elements relative to the total mass of the solid composition.

[0090]

[0091] As shown in Table 2, a solid composition containing a copolymer containing TFE units and PAVE units, and a metal element, wherein the content of PAVE units is 3.0 to 3.8 mass% based on all units contained in the copolymer, the content of TFE units is 96.2 to 97.0 mass% based on all units contained in the copolymer, the MFR of the solid composition is 1.4 to 2.9 g / 10 min, the melting point of the copolymer is 298°C or higher, and the total number of specific functional groups possessed by the copolymer is 10 or more ... ６ It was confirmed that by using a solid composition having 150 particles or less per particle and a metal element content of 0.0100 to 2.0000 ppm by mass relative to the total mass of the solid composition, it is possible to form a molded article that is excellent in all of high-temperature tensile elongation, electrical insulation, heat resistance, flexural modulus, high-temperature tensile modulus, low colorability, and low foaming property (Examples 1 to 6).

[0092] The entire contents of the specification, claims and abstract of Japanese Patent Application No. 2024-092260, filed on June 6, 2024, are hereby incorporated by reference as the disclosure of the present invention.

Claims

1. A solid composition comprising a copolymer containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether), and a metal element, wherein the content of the units based on perfluoro(alkyl vinyl ether) in the copolymer is 2.9 to 4.0% by mass based on all units contained in the copolymer, the content of the units based on tetrafluoroethylene is 96.0 to 97.1% by mass based on all units contained in the copolymer, the melt flow rate of the solid composition measured at a temperature of 372°C in accordance with ASTM D1238 is 1.4 to 2.9 g / 10 min, the melting point of the copolymer is 298°C or higher, and the -CF=CF group contained in the copolymer is 1.4 to 2.9 g / 10 min. ２ , -CF ２ H, -COF, -COOH, -COOCH ３ , -CONH ２ and -CH ２ The total number of OH functional groups is 10 ６ a total mass of the solid composition, wherein the number of particles per particle is 150 or less, and the content of the metal element is 0.0100 to 2.0000 ppm by mass relative to the total mass of the solid composition.

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

3. An extrusion molded product obtained by extruding the solid composition according to claim 1 or 2.

4. A blow-molded article obtained by blow-molding the solid composition according to claim 1 or 2.

5. A transfer molded article obtained by transfer molding the solid composition according to claim 1 or 2.

6. A press-molded product obtained by press-molding the solid composition according to claim 1 or 2.

7. An injection-molded article obtained by injection molding the solid composition according to claim 1 or 2.

8. A coated electric wire comprising a conductor and a coating layer disposed on the surface of the conductor and obtained by molding the solid composition according to claim 1 or 2.

9. A molded article obtained by molding the solid composition according to claim 1 or 2, wherein the molded article is a piping member, an electric wire coating material, a tube, a film or a compressed member.

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