Powder, molded article, and method for producing powder

Abstract

The present invention provides a PFA powder that simplifies the drying process after polymerization and before sending to the next process, a molded article obtained from the powder, and a method for producing the powder. [Solution] A powder mainly composed of a copolymer containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether), wherein the moisture penetration rate coefficient of the powder is 1.0 × 10 -5 ~1.0×10 -3 g 2 A powder having a density of / s, a molded article obtained from the powder, and a method for producing the powder.

Description

[Technical Field]

[0001] This disclosure relates to powders, molded articles, and methods for producing powders. [Background technology]

[0002] A copolymer of tetrafluoroethylene and perfluoro(alkyl vinyl ether) (hereinafter also referred to as "PFA") is known as a fluororesin that has excellent mechanical, chemical, and electrical properties and can be melt-processed. PFA is used in a wide variety of applications, including semiconductor components, automotive components, various coating materials, and various packaging materials.

[0003] Patent Document 1 describes PFA having low drug permeability as a forming material for tubes and the like. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2001-151825 [Overview of the project] [Problems that the invention aims to solve]

[0005] In many cases, fluoropolymer resins such as PFA are synthesized in powder form in a polymerization medium containing water. When sending the fluoropolymer powder to subsequent processes such as melt molding or end-group modification, the resin powder is dried beforehand to prevent transport problems, molding defects, and equipment corrosion due to residual moisture. On the other hand, the drying process requires a long time and energy, so it is desirable to simplify the process. In view of these circumstances, this disclosure relates to a PFA powder that can simplify the drying process after polymerization and before sending to subsequent processes, a molded article obtained from the powder, and a method for producing the powder. [Means for solving the problem]

[0006] The means for solving the above problems include the following embodiments. <1> A powder mainly composed of a copolymer containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether), wherein the moisture penetration rate coefficient of the powder is 1.0 × 10⁻⁶ -5 ~1.0×10 -3 g 2 / s, powder. <2> The content of the tetrafluoroethylene-based units is 92.0 to 98.0% by mass relative to the total monomer units of the copolymer. <1> The powder described above. <3> The proportion of the units based on the perfluoro(alkyl vinyl ether) is 2.0 to 8.0% by mass relative to the total monomer units of the copolymer. <1> or <2> The powder described above. <4> The melt flow rate, measured at 372°C according to ASTM D1238, is 1.0 to 40.0 g / 10 min. <1> ~ <3> The powder described in any one of the items. <5> The aforementioned unit based on perfluoro(alkyl vinyl ether) includes a unit based on perfluoro(propyl vinyl ether), <1> ~ <4> The powder described in any one of the items. <6> <1> ~ <5> A molded article of the powder described in any one of the items. <7> The process involves polymerizing tetrafluoroethylene and perfluoro(alkyl vinyl ether) in a polymerization medium in a reaction vessel equipped with helical ribbon blades as stirring blades, in the presence of a radical initiator and a chain transfer agent, to produce a copolymer powder containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether). The radical initiator is diacyl peroxide, The chain transfer agent is an organic compound having 3 to 12 carbon atoms, consisting of at least one atom selected from the group consisting of hydrogen atoms, fluorine atoms, and chlorine atoms, and only carbon atoms. The polymerization medium comprises water, a nonionic fluorine-containing organic compound, and an alcohol, and separates into two phases at 25°C. The aforementioned alcohol does not have a methylene hydrogen atom, a methine hydrogen atom, or a methyl hydrogen atom adjacent to a heteroatom. Wherein the maximum diameter of the stirring blade is d [m], the inner diameter of the reaction vessel is D [m], and the rotation speed of the stirring blade per second is n [s -1 , the volume of the reaction vessel is V [m 3 , d / D is 0.90 or more, and n 3 ·d 5 / V is 1.00 to 15.00 m 2 / s 3 , which is a method for producing powder.

Effects of the Invention

[0007] According to the present disclosure, there are provided a PFA powder capable of simplifying a drying step after polymerization and before feeding to a post-process, a molded article obtained from the powder, and a method for producing the powder.

Mode for Carrying Out the Invention

[0008] Hereinafter, modes for carrying out embodiments of the present disclosure will be described in detail. However, the embodiments of the present disclosure are not limited to the following embodiments. In the following embodiments, the constituent elements (including element steps and the like) are not essential unless explicitly stated. The same applies to numerical values and their ranges, which do not limit the embodiments of the present disclosure.

[0009] In the present disclosure, the term "step" includes not only a step independent of other steps, but also a step that cannot be clearly distinguished from other steps as long as the object of the step is achieved. In the present disclosure, the numerical range indicated using "~" includes the numerical values described before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in the present disclosure, the upper limit or lower limit described in one numerical range may be replaced with the upper limit or lower limit of the numerical range described in other stepwise descriptions. In addition, in the numerical ranges described in the present disclosure, the upper limit or lower limit of the numerical range may be replaced with the values shown in the examples. In this disclosure, each component may contain multiple types of the corresponding substance. If multiple types of the substance corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple types of substances present in the composition, unless otherwise specified. In this disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In this disclosure, "polymer" refers to a compound formed by the polymerization of monomers. That is, a "polymer" has multiple structural units. In this disclosure, "polymer" is a compound obtained by copolymerizing two or more monomers. A copolymer containing units based on monomer X and units based on monomer Y is a compound obtained by copolymerizing at least monomer X and monomer Y, and other monomers may or may not be further copolymerized. In this disclosure, the term "unit" of a polymer refers to the collective term for an atomic group derived from one monomer molecule, which is directly formed by the polymerization of monomers, and an atomic group obtained by chemically transforming a part of the above atomic group. In the following, as appropriate, units derived from individual monomers will be referred to by adding "unit" to the monomer name.

[0010] <Powder> The powder of this disclosure is a powder mainly composed of a copolymer containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether), wherein the water penetration rate coefficient of the powder is 1.0 × 10 -5 ~1.0×10 -3 g 2 It is / s. Hereinafter, copolymers containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether) will also be referred to as "this copolymer," units based on tetrafluoroethylene will also be referred to as "TFE units," and units based on perfluoro(alkyl vinyl ether) will also be referred to as "PAVE units." In the context of powders, the "main component" refers to the component that accounts for 50% or more by mass of the powder.

[0011] The powder of this disclosure simplifies the drying process after polymerization and before sending to subsequent processes. The powder of this disclosure has a moisture penetration rate coefficient below the upper limit, resulting in low wettability and reduced moisture retention within the powder. On the other hand, the powder of this disclosure has a moisture penetration rate coefficient above the lower limit, allowing water to penetrate the pores of the powder and improving drainage, thus preventing excessive moisture retention outside the powder. Therefore, by having the moisture penetration rate coefficient within the specified range, the amount of moisture carried from the polymerization reaction to subsequent processes is reduced, thereby shortening the drying time. However, the form of the powder of this disclosure is not limited in any way by the above-described mechanism.

[0012] The moisture penetration rate coefficient of the powder is 1.0 × 10⁻⁶. -5 g 2 It is greater than / s, and from the above perspective, 5.0 × 10 -5 g 2 Preferably 9.0 × 10 -5 g 2 / s or more is more preferable, 1.0 × 10 -4 g 2 It may be 5.0 × 10 -4 g 2 It may be greater than / s. Also, the moisture penetration rate coefficient of the powder is 1.0 × 10 -3 g 2 It is less than / s, and from the above perspective, 9.0 × 10 -4 g 2 It may be less than / s, 7.0 × 10 -4 g 2 It may be less than / s, 5.0 × 10 -4 g 2 It may be less than / s, 4.8 × 10 -4 g 2 It may be less than / s.

[0013] The water penetration rate coefficient is measured based on the Lubas-Washburn equation by graphing the immersion time and the mass of water penetrating. For example, it can be determined by measuring it with a wettability evaluation device (e.g., Penetration Analyzer PNT-N (Hosokawa Micron Corporation)). The powder is placed in a cell equipped with filter paper on the bottom, and the bottom surface of the cell is immersed in 36°C water. The mass of water penetrating the powder is measured by W L (g) Let t be the time it takes for the water to penetrate, and calculate the water infiltration rate coefficient using the following equation (1). Equation (1): Moisture permeation rate coefficient (g 2 / s) = W L 2 / t

[0014] The moisture penetration rate coefficient can be adjusted by the manufacturing conditions of the powder, such as the type of radical initiator, chain transfer agent, polymerization medium used in polymerization, and stirring conditions. For example, when diacyl peroxide is used as a radical initiator, the resulting copolymer tends to be hydrophobic, and the water penetration rate coefficient tends to fall within the above range. When an organic compound having 3 to 12 carbon atoms, consisting of at least one selected from the group consisting of hydrogen atoms, fluorine atoms, and chlorine atoms, as well as carbon atoms, is used as a chain transfer agent, the resulting copolymer tends to be hydrophobic, and the water permeation rate coefficient tends to fall within the above range. When a polymerization medium containing water, a nonionic fluorine-containing organic compound, and an alcohol is used, and the polymerization medium separates into two phases at 25°C, and the alcohol is a compound that does not have methylene hydrogen atoms, methine hydrogen atoms, or methyl hydrogen atoms adjacent to heteroatoms, the resulting copolymer tends to be hydrophobic, and the water penetration rate coefficient tends to fall within the above range. Furthermore, let d[m] be the maximum diameter of the reaction vessel's impeller, D[m] be the inner diameter of the reaction vessel, and n[s] be the rotation speed of the impeller per second. -1 ], the volume of the reaction vessel is V[m³ 3 When ] is set, d / D and n 3 ·d 5 By setting / V within a certain range, the particle size, particle size distribution, and particle shape of the powder can be adjusted, making it easier for the moisture penetration rate coefficient to fall within the above range.

[0015] The powder of this disclosure mainly consists of the copolymer, i.e., contains 50% by mass or more. The powder of this disclosure may contain 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more of the copolymer, or may contain only the copolymer.

[0016] A narrow particle size distribution of the powder is preferable from the viewpoint of easily adjusting the moisture penetration rate coefficient to a specific range. The circularity of the powder is preferably 0.30 or higher, more preferably 0.40 or higher, and even more preferably 0.50 or higher, from the viewpoint of easily adjusting the moisture penetration rate coefficient to a specific range. The upper limit of the circularity of the powder is 1. The circularity can be determined by dispersing the sample to be measured in isopropanol solvent and performing image analysis of the particle shape using a particle shape image analyzer (PITA-04M, manufactured by Seishin Corporation), and then using the following formula (2). Equation (2): Circularity = 4πS / L 2 S: Projected area L: Perimeter length

[0017] From the viewpoint of increasing fluidity during melting and improving moldability, and from the viewpoint of improving the low-speed tear strength of the molded article, the melt flow rate (MFR) of the powder is preferably 1.0 g / 10 min or more, more preferably 2.0 g / 10 min or more, and even more preferably 10.0 g / 10 min or more. From the viewpoint of easily improving the tensile strength of the molded article, the MFR is preferably 40.0 g / 10 min or less, more preferably 35.0 g / 10 min or less, even more preferably 30.0 g / 10 min or less, and may also be 20.0 g / 10 min or less, or 15.0 g / 10 min or less. From this viewpoint, the MFR is preferably 1.0 to 40.0 g / 10 min, more preferably 2.0 to 35.0 g / 10 min, and even more preferably 10.0 to 30.0 g / 10 min. A specific example of a method to bring the MFR of the powder within the above range is to adjust the molecular weight of the copolymer. The larger the molecular weight of the copolymer, the smaller the MFR. MFR stands for Mass Flow Rate (g), which is the mass of molten material flowing out of a 2.095 mm diameter, 8 mm long orifice in 10 minutes, measured under conditions of a temperature of 372°C and a load of 5 kg, in accordance with ASTM D1238. The copolymer and other components are described in detail below.

[0018] [This copolymer] This copolymer contains TFE units and PAVE units.

[0019] The TFE unit content is not particularly limited. From the viewpoint of increasing the strength of the molded article, the TFE unit content is preferably 92.0% by mass or more, more preferably 92.5% by mass or more, and even more preferably 93.0% by mass or more, relative to the total monomer units contained in the copolymer. From the viewpoint of increasing the flexibility of the molded article, the TFE unit content is preferably 98.0% by mass or less, more preferably 97.5% by mass or less, and even more preferably 97.0% by mass or less, relative to the total monomer units contained in the copolymer. From this viewpoint, the TFE unit content is preferably 92.0 to 98.0% by mass, more preferably 92.5 to 97.5% by mass, and even more preferably 93.0 to 97.0% by mass, relative to the total monomer units contained in the copolymer.

[0020] The PAVE unit content is not particularly limited. From the viewpoint of increasing the flexibility of the molded article, the PAVE unit content is preferably 2.0% by mass or more, more preferably 2.5% by mass or more, and even more preferably 3.0% by mass or more, relative to the total monomer units contained in the copolymer. From the viewpoint of increasing the crystallinity of the copolymer and increasing the strength of the molded article, the PAVE unit content is preferably 8.0% by mass or less, more preferably 7.5% by mass or less, even more preferably 7.0% by mass or less, particularly preferably 6.0% by mass or less, and extremely preferably 5.0% by mass or less, relative to the total monomer units contained in the copolymer. From this viewpoint, the PAVE unit content is preferably 2.0 to 8.0% by mass, more preferably 2.5 to 7.5% by mass, even more preferably 3.0 to 7.0% by mass, particularly preferably 3.0 to 6.0% by mass, and extremely preferably 3.0 to 5.0% by mass, relative to the total monomer units contained in the copolymer.

[0021] As PAVE, the monomer represented by formula (1) is preferred. CF2 = CF - O - Rf 1 (1) In formula (1), Rf 1 Rf represents a perfluoroalkyl group with 1 to 10 carbon atoms. 1 The number of carbon atoms in the perfluoroalkyl group represented by is preferably 1 to 8, more preferably 1 to 6, even more preferably 1 to 5, and particularly preferably 1 to 3, from the viewpoint of superior polymerization reactivity. The perfluoroalkyl group may be linear or branched.

[0022] Specific examples of PAVE include perfluoro(methyl vinyl ether) (PMVE), perfluoro(ethyl vinyl ether) (PEVE), and perfluoro(propyl vinyl ether) (PPVE). From the viewpoint of balancing raw material costs and ease of handling during polymerization, PMVE or PPVE is preferred, and PPVE is more preferred. PAVE may be used alone or in combination of two or more types.

[0023] In this copolymer, from the viewpoint of exhibiting the properties of TFE units and PAVE units well, and from the viewpoint of the molded article not being easily deformed by compression or tension, the total content of TFE units and PAVE units is preferably 95.0% by mass or more, more preferably 98.0% by mass or more, even more preferably 99.0% by mass or more, and may be 100.0% by mass, relative to the total monomer units contained in this copolymer.

[0024] This copolymer may or may not contain units based on other monomers copolymerizable with TFE and PAVE, in addition to TFE and PAVE units. Other monomers include, for example, ethylene, vinylidene fluoride (VdF), hexafluoropropylene (HFP), and CX. 1 X 2 =CX 3 (CF2) n X 4 (In the formula, X 1, X 2 , and X 3 Each of these independently represents either a hydrogen atom or a fluorine atom, and X 4 ) represents a hydrogen atom, a fluorine atom, or a chlorine atom, and n is an integer from 1 to 10. ) Monomers represented by CF2=CF-OCH2-Rf 2 (In the formula, Rf 2 represents a perfluoroalkyl group having 1 to 5 carbon atoms. Examples include monomers represented by ). If the copolymer contains units based on other monomers, the content of units based on other monomers is preferably 5.0% by mass or less, more preferably 2.0% by mass or less, and even more preferably 1.5% by mass or less, relative to the total monomer units contained in the copolymer.

[0025] If the copolymer contains units based on other monomers, it is preferable that the copolymer contains TFE units, PAVE units, and HFP units. If the copolymer contains TFE units, PAVE units, and HFP units, the content of HFP units is preferably 0.1% by mass or more, and more preferably 0.5% by mass or more, relative to the total monomer units contained in the copolymer. The content of HFP units is preferably 10.0% by mass or less, and more preferably 5.0% by mass or less, relative to the total monomer units contained in the copolymer.

[0026] From the viewpoint of exhibiting the properties of TFE units and PAVE units well, and from the viewpoint of the molded article not being easily deformed by compression or tension, it is preferable that this copolymer does not contain units based on the other monomers mentioned above, and contains only TFE units and PAVE units.

[0027] The respective contents of TFE units, PAVE units, and other monomer-based units in this copolymer are as follows: 19 It can be measured by known methods such as F-NMR (nuclear magnetic resonance analysis).

[0028] From the viewpoint of excellent mechanical strength of the molded article, the melting point of this copolymer is preferably 298.0°C or higher, more preferably 299.0°C or higher, and even more preferably 300.0°C or higher. From the viewpoint of excellent moldability of this copolymer, the melting point is preferably 310.5°C or lower, more preferably 310.0°C or lower, and even more preferably 309.5°C or lower. One method for setting the melting point of this copolymer within the above range is to lower the polymerization temperature during the production of this copolymer. The melting point of this 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 scanning differential thermal analyzer.

[0029] The term "polymer" here does not refer to a so-called elastomer. An elastomer is a copolymer that does not have a melting point.

[0030] [Other ingredients] The powder may or may not contain components other than the copolymer. For example, the powder may contain resins other than the copolymer, heat stabilizers, antioxidants, colorants, UV absorbers, fillers, crosslinking agents, crosslinking aids, organic peroxides, etc. If the powder contains components other than the copolymer, the total content of such components is 50 parts by mass or less, preferably 40 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 1 part by mass or less, and particularly preferably 0.1 parts by mass or less, relative to the total amount of the powder. The total content of components other than the copolymer may be 0.0000001 parts by mass or more, 0.0000005 parts by mass or more, or 0.000001 parts by mass or more, relative to the total amount of the powder. From this viewpoint, the total content of components other than the copolymer may be 0.0000001 to 50 parts by mass, relative to the total amount of the powder.

[0031] [Metallic elements] From the viewpoint of suppressing the incorporation of metal into molded products, it is preferable that the amount of metal elements in the powder be kept low. For example, the 32 metal elements that can be measured by inductively coupled plasma mass spectrometry (ICP-MS) are aluminum (Al), arsenic (As), silver (Ag), antimony (Sb), barium (Ba), boron (B), beryllium (Be), bismuth (Bi), cadmium (Cd), calcium (Ca), copper (Cu), cobalt (Co), chromium (Cr), cesium (Cs), iron (Fe), gallium (Ga), lead (Pb), indium (In), and lithium (Li). The total content of ), magnesium (Mg), manganese (Mn), molybdenum (Mo), nickel (Ni), potassium (K), sodium (Na), rubidium (Rb), strontium (Sr), titanium (Ti), tin (Sn), vanadium (V), zinc (Zn), and zirconium (Zr) is preferably 2.0000 ppm by mass or less, more preferably 1.8000 ppm by mass or less, and even more preferably 1.5000 ppm by mass or less, relative to the total mass of the powder.

[0032] The total content of the 32 metal elements listed above is measured by ICP-MS as follows: The powder is placed in a platinum crucible and ashed in a high-temperature electric heating furnace, then treated with sulfuric acid fumes and dissolved in dilute nitric acid. The resulting liquid is then measured using an inductively coupled plasma mass spectrometer (e.g., ICP-MS 7500cs (product name), manufactured by Agilent Technologies) and the content of the 32 metal elements is summed up using the absolute calibration curve method.

[0033] The metal elements in the powder originate from, for example, the metal elements contained in the materials (monomers, polymerization solvents, etc.) used in the production of the copolymer. Therefore, one method for adjusting the metal element content is to use materials with a low metal element content in the production of the copolymer. For example, when copolymerizing TFE and PAVE, it is preferable to use a polymerization medium (e.g., ultrapure water) with a low metal element content.

[0034] <Method for producing powder> The method for producing the powder of this disclosure is not particularly limited. The method for producing the powder may include a step for producing the copolymer (hereinafter also referred to as the "polymer production step"). The copolymer manufacturing process includes producing the copolymer using the above monomers (TFE, PAVE, and other monomers as needed) by methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization, with the method of producing the copolymer by solution polymerization being preferred. In the production of this copolymer, in addition to the monomers mentioned above, polymerization initiators, polymerization media, chain transfer agents, emulsifiers, pH adjusters, etc., can be used.

[0035] The polymerization initiator is preferably a radical polymerization initiator with a half-life of 10 hours and a temperature range of 0 to 100°C, and more preferably a radical polymerization initiator with a temperature range of 20 to 90°C. Specific examples of polymerization initiators include the various polymerization initiators exemplified in International Publication No. 2013 / 015202. The polymerization initiator may be used alone or in combination of two or more types. Specifically, examples of radical initiators include azo radical initiators and peroxide radical initiators. Radical initiators may be used individually or in combination of two or more. Examples of azo radical initiators include 2,2'-azobis(isobutyronitrile) (AIBN), 2,2'-azobis(2-methylbutyronitrile) (AMBN), 2,2'-azobis(2,4-dimethylvaleronitrile) (ADVN), 1,1'-azobis(1-cyclohexanecarbonitride) (ACHN), dimethyl-2,2'-azobisisobutyrate (MAIB), 4,4'-azobis(4-cyanovaleric acid) (ACVA), 1,1'-azobis(1-acetoxy-1-phenylethane), 2,2'-azobis(2-methylbutylamide), and 2,2' Examples include -azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylamidinopropane) dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane], 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], 2,2'-azobis(2,4,4-trimethylpentane), 2-cyano-2-propylazoformamide, 2,2'-azobis(N-butyl-2-methylpropionamide), and 2,2'-azobis(N-cyclohexyl-2-methylpropionamide). Examples of peroxide-based radical initiators include organic peroxides and inorganic peroxides. Organic peroxides include peroxy dicarbonates such as diisopropyl peroxydicarbonate; peroxyesters such as tert-butyl peroxypivalate, tert-butyl peroxyisobutyrate, and tert-butyl peroxyacetate; and non-fluorinated diacyl peroxides such as isobutyryl peroxide, octanoyl peroxide, benzoyl peroxide, and lauroyl peroxide; (Z(CF2) p Examples include fluorine-containing diacyl peroxides such as COO)2 (where Z is a hydrogen atom, a fluorine atom, or a chlorine atom, and p is an integer from 1 to 10), such as heptafluorobutyroyl peroxide; and perfluorotert-butyl peroxide. Examples of inorganic peroxides include potassium persulfate, sodium persulfate, and ammonium persulfate. Organic peroxides are preferred from the viewpoint of having a high polymerization rate, being less prone to discoloration when the polymer is heated, and having excellent heat resistance in the resulting copolymer. The amount of polymerization initiator used is preferably 0.01 to 0.9 parts by mass, and more preferably 0.03 to 0.5 parts by mass, per 100 parts by mass of monomer used.

[0036] Polymerization media include water, organic solvents, and mixed solvents of water and organic solvents. A single polymerization media may be used, or two or more may be used in combination.

[0037] Deionized water is preferred as the water source, and ultrapure water is more preferred. From the viewpoint of easily obtaining this copolymer with a low content of metal elements, the metal element content of water 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. The metal element content is preferably 0 ppb by mass or more. The method for achieving the above-mentioned metal element content is not particularly limited, and examples include methods such as filtering water with various filters to reduce the metal element content. The content of metal elements in water can be measured using the absolute calibration curve method with ICP-MS, similar to the method used to measure the content of metal elements in powders described above. The electrical conductivity of water is preferably 1.00 μS / cm or less, and more preferably 0.08 μS / cm or less. The lower limit is preferably 0 μS / cm or more. The magnitude of the electrical conductivity of water is related to the amount of metallic elements in the water; the more metallic elements there are, the higher the electrical conductivity of the water. The electrical conductivity of water can be measured by known measurement methods.

[0038] Examples of organic solvents include fluorine-containing organic compounds such as perfluorocarbons, hydrofluorocarbons, and hydrofluoroethers, as well as alcohols.

[0039] As the fluorine-containing organic compound, nonionic fluorine-containing organic compounds are preferred. Examples of nonionic fluorine-containing perfluorocarbons include n-perfluorohexane, n-perfluoroheptane, perfluorocyclobutane, perfluorocyclohexane, and perfluorobenzene. Examples of hydrofluorocarbons, which are nonionic fluorine-containing compounds, include 1,1,2,2-tetrafluorocyclobutane, CF3CFHCF2CF2CF3, CF3(CF2)4H, CF3CF2CFHCF2CF3, CF3CFHCFHCF2CF3, CF2HCFHCF2CF2CF3, CF3(CF2)5H, CF3CH(CF3)CF2CF2CF3, CF3CF(CF3)CFHCF2CF3, CF3CF(CF3)CFHCFHCF3, CF3CH(CF3)CFHCF2CF3, CF3CF2CH2CH3, and CF3(CF2)3CH2CH3. Examples of nonionic fluorinated hydrofluoroethers include methoxynononafluorobutane (HFE-7100), 1,1-difluoroethyl-2,2,2-trifluoroethyl ether (HFE-365mf-c), 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (HFE-347pc-f), 1,1-difluoroethyl-2,2,3,3,3-pentafluoropropyl ether (HFE-467sc-f), ethoxynononafluorobutane (HFE-569s1), 1,1,2,3,3,3-hexafluoropropyl-2,2,2-trifluoroethyl ether (HFE-449mec-f), 1,1,2,2-tetrafluoroethyl-2,2,3,3,3-pentafluoropropyl ether (HFE-449pc-f), and 1,1-difluoroethyl-2 Examples include 2,3,3-tetrafluoropropyl ether (HFE-476pcf-c), 1,1,2,3,3,3-hexafluoropropyl-2,2,3,3,3-pentafluoropropyl ether (HFE-54-11mec-f), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (HFE-458pc-fc), 1,1,2,3,3,3-hexafluoropropyl-2,2,3,3-tetrafluoropropyl ether (HFE-55-10mec-fc), and 3-methoxy-4-trifluoromethyl-1,1,1,2,2,3,4,5,5,5-decafluoropentane (C2F5CF(OCH3)CF(CF3)CF3), and from the viewpoint of polymerization reactivity, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether is preferred.

[0040] Examples of alcohols include tert-butyl alcohol. From the viewpoint of preventing chain transfer, it is preferable that the alcohol used as a polymerization medium does not contain methylene hydrogen atoms, methine hydrogen atoms, or methyl hydrogen atoms adjacent to heteroatoms. Methylene hydrogen atoms are hydrogen atoms of the methylene group (-CH2-), methine hydrogen atoms are hydrogen atoms of the methine group (-CH-), and methyl hydrogen atoms adjacent to heteroatoms are hydrogen atoms of the methyl group (-CH3) adjacent to heteroatoms.

[0041] As the polymerization medium, a mixed solvent containing water and a fluorinated solvent is preferred, and from the viewpoint of easily controlling the water penetration rate coefficient within a suitable range, a mixed solvent containing water, a fluorinated organic compound, and an alcohol is more preferred, and a mixed solvent containing water, a nonionic fluorinated organic compound, and an alcohol is even more preferred. From the viewpoint of suspension properties and economy, the amount of nonionic fluorinated organic compound used is preferably 10% by mass or more and less than 100% by mass, and more preferably 50 to 90% by mass, relative to the total mass of the mixed solvent. From the viewpoint of easily controlling the water penetration rate coefficient within a suitable range, the amount of alcohol used is preferably 1 to 10% by mass, and more preferably 2 to 5% by mass, relative to the total mass of the mixed solvent.

[0042] The amount of polymerization medium used is preferably 3 times or more by mass ratio of the amount of monomer used, and more preferably 4 times or more. Furthermore, the amount of polymerization medium used is preferably 20 times or less by mass ratio of the amount of monomer used, and more preferably 17 times or less. From this viewpoint, the amount of polymerization medium used is preferably 3 to 20 times, and more preferably 4 to 17 times, by mass ratio of the amount of monomer used.

[0043] From the viewpoint of having a large chain transfer constant and requiring a small amount of additive, 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 propane, n-pentane, n-hexane, and cyclohexane; hydrofluorocarbons such as CF2H2; 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 are preferred as chain transfer agents. In particular, from the viewpoint of a higher chain transfer constant and greater stability of the end groups of the copolymer, at least one selected from the group consisting of alcohols, hydrocarbons, and hydrofluorocarbons is preferred, at least one selected from the group consisting of alcohols and hydrocarbons is more preferred, and alcohol is even more preferred. As the alcohol, methanol or ethanol is preferred, and methanol is more preferred from the viewpoint of reactivity and availability. The chain transfer agent may be used alone or in combination of two or more. Note that the chain transfer agent is a compound that causes chain transfer, and compounds that do not cause chain transfer, such as alcohols that do not cause chain transfer, are not referred to as chain transfer agents. The amount of chain transfer agent used is preferably 0.001 times or more by mass ratio of the amount of monomer used, and more preferably 0.005 times or more. Furthermore, the amount of chain transfer agent used is preferably 5 times or less by mass ratio of the amount of monomer used, and more preferably 4 times or less. From this viewpoint, the amount of chain transfer agent used is preferably 0.001 to 5 times, and more preferably 0.005 to 4 times, by mass ratio of the amount of monomer used.

[0044] As for the compounds used in polymerization (monomer components, polymerization initiators, chain transfer agents, emulsifiers, pH adjusters, etc., excluding aqueous media), it is preferable not to use compounds containing metal elements, from the viewpoint of easily obtaining pellets with a low metal element content.

[0045] The polymerization temperature is preferably 15 to 60°C, more preferably 20 to 58°C, and even more preferably 25 to 55°C. A polymerization temperature of 15°C or higher may result in excellent polymerizability. A polymerization temperature of 60°C or lower may improve the melting point of the copolymer. The polymerization pressure is preferably 0.5 to 3.0 MPa, and more preferably 0.9 to 2.5 MPa. The polymerization time is preferably 1 to 12 hours.

[0046] If an aqueous dispersion containing the copolymer is obtained by polymerization, the copolymer can be recovered by coagulating, washing, and drying the copolymer contained in the aqueous dispersion. Alternatively, if 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 it. The copolymer can also be recovered in powder form by drying.

[0047] The powder is dried at a temperature above the boiling point of the polymerization medium, for example, 100 to 250°C, preferably 120 to 200°C. Drying is preferably carried out until no further mass loss of the powder occurs due to evaporation of the polymerization medium. For example, the drying time is preferably 0.5 hours or more, more preferably 1 hour or more, and even more preferably 1.5 hours or more. On the other hand, the drying time can be shortened with the powder of this disclosure. From the viewpoint of simplifying the process and reducing energy, the drying time is preferably 20 hours or less, more preferably 10 hours or less, and even more preferably 3 hours or less. From this viewpoint, the drying time is preferably 0.5 to 20 hours, more preferably 1 to 15 hours, and even more preferably 1.5 to 3 hours.

[0048] In one embodiment, the method for producing the powder includes polymerizing tetrafluoroethylene and perfluoro(alkyl vinyl ether) in a polymerization medium in the presence of a radical initiator and a chain transfer agent in a reaction vessel equipped with a helical ribbon blade as a stirring blade, to produce a copolymer powder containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether). The radical initiator is diacyl peroxide, The chain transfer agent is an organic compound having 3 to 12 carbon atoms, consisting of at least one atom selected from the group consisting of hydrogen atoms, fluorine atoms, and chlorine atoms, and only carbon atoms. The polymerization medium comprises water, a nonionic fluorine-containing organic compound, and an alcohol, and separates into two phases at 25°C, wherein the alcohol does not contain methylene hydrogen atoms, methine hydrogen atoms, or methyl hydrogen atoms adjacent to heteroatoms. Let d[m] be the maximum diameter of the stirring blade, D[m] be the inner diameter of the reaction vessel, and n[s] be the rotation speed of the stirring blade per second. -1 ], the volume of the reaction vessel is V[m³] 3 ], and when d / D is 0.90 or greater, n 3 ·d 5 / V is 1.00~15.00m 2 / s 3 That is the case. Hereinafter, the method for producing the powder in this embodiment will also be referred to as "Manufacturing Method A". Unless otherwise specified, the details of the powder manufacturing method in Manufacturing Method A are as described above.

[0049] In manufacturing method A, diacyl peroxide is used as a radical initiator. Diacyl peroxide makes the copolymer hydrophobic without adding polar groups to the ends of the copolymer, resulting in a water penetration rate coefficient of 1.0 × 10⁻⁶. -5 ~1.0×10 -3 g 2 This copolymer, which has a coefficient of / s, is readily available. Examples of diacyl peroxides include non-fluorinated diacyl peroxides and fluorinated diacyl peroxides, which are among the "peroxide-based radical initiators" mentioned above.

[0050] In manufacturing method A, an organic compound having 3 to 12 carbon atoms, consisting of at least one atom selected from the group consisting of hydrogen, fluorine, and chlorine atoms, as well as carbon atoms, is used as a chain transfer agent. Because such a chain transfer agent makes the copolymer hydrophobic without adding polar groups to the copolymer, the water penetration rate coefficient is 1.0 × 10⁻⁶. -5 ~1.0×10 -3 g 2 This copolymer, which has a coefficient of s, is readily available. The chain transfer agent preferably contains at least one selected from the group consisting of hydrogen atoms and fluorine atoms, and more preferably contains hydrogen atoms. Specific examples of chain transfer agents include those mentioned above, and from the viewpoint of obtaining a good water penetration rate coefficient, hydrocarbons such as propane, n-pentane, n-hexane, and cyclohexane are preferred.

[0051] In manufacturing method A, a polymerization medium is used that contains water, a nonionic fluorine-containing organic compound, and an alcohol, and separates into two phases at 25°C. Such a polymerization medium is preferable because it easily combines the advantages of solution polymerization, which is less prone to scaling on the reactor walls, and suspension polymerization, which is advantageous in terms of heat removal and batch yield. In addition, the presence of alcohol changes the liquid properties such as surface tension, and the water penetration rate coefficient becomes 1.0 × 10⁻⁶. -5 ~1.0×10 -3 g 2 This copolymer, which has a coefficient of / s, is readily available. Examples of water and nonionic fluorine-containing organic compounds include those mentioned above.

[0052] A polymerization medium comprising water, a nonionic fluorine-containing organic compound, and an alcohol, which separates into two phases at 25°C, is a mixture of water, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, and tert-butyl alcohol.

[0053] In manufacturing method A, the alcohol used as the polymerization medium does not contain methylene hydrogen atoms, methine hydrogen atoms, or methyl hydrogen atoms adjacent to heteroatoms. Since such an alcohol does not undergo chain transfer, it does not add hydrophilic groups to the ends of the copolymer, and the water permeation rate coefficient is 1.0 × 10⁻⁶. -5 ~1.0×10 -3 g 2 This copolymer, which has a coefficient of / s, is readily available. Examples of alcohols that do not have a methylene hydrogen atom, a methine hydrogen atom, or a methyl hydrogen atom adjacent to a heteroatom include tert-butyl alcohol.

[0054] In manufacturing method A, polymerization is carried out in a reaction vessel equipped with a helical ribbon blade as a stirring blade. The maximum diameter of the stirring blade is d [m], the inner diameter of the reaction vessel is D [m], and the rotation speed of the stirring blade is n [s]. -1 ], the volume of the reaction vessel is V[m³ 3 ], and when d / D is 0.90 or greater, n 3 ·d 5 / V is 1.00 to 15.00 m 2 / s 3 .

[0055] A helical ribbon blade is a stirring blade provided with a helically wound strip-shaped blade, and is excellent in stirring power, so that a suitable polymerization rate and batch yield are easily obtained. The helical ribbon blade may be a single helical ribbon blade or a double helical ribbon blade, and a double helical ribbon blade is preferred from the viewpoint of better stirring power.

[0056] The volume and inner diameter of the reactor can be appropriately adjusted according to the production scale of the powder. Further, the maximum diameter and rotation speed of the stirring blade are adjusted according to the volume and inner diameter of the reactor so that the above d / D and n 3 ·d 5 / V is preferably within a range that satisfies the condition. In one aspect, the rotation speed of the stirring blade is preferably 50 to 500 rpm, more preferably 60 to 450 rpm, and still more preferably 80 to 400 rpm.

[0057] d / D is 0.90 or more, preferably 0.91 or more, and more preferably 0.92 or more. When d / D is not less than the above upper limit, the polymerization rate tends to be good, and the bulk density of the polymer slurry is less likely to decrease, so the batch yield tends to be good. From the viewpoint of polymerization equipment safety, d / D is preferably 0.98 or less, more preferably 0.97 or less, and still more preferably 0.96 or less. From this viewpoint, d / D is preferably 0.90 to 0.98, more preferably 0.91 to 0.97, and still more preferably 0.92 to 0.96.

[0058] n 3 ·d 5 / V is an index of stirring power, and n 3 ·d 5 / V, the larger the value, the greater the stirring power. n 3 ·d 5 / V is 1.00 m 2 / s 3 or more, preferably 1.50 m 2 / s 3 or more, more preferably 2.00 m 2 / s3 The above is more preferable. n 3 ·d 5 / V is equal to or higher than the lower limit value described above, the polymerization rate tends to be favorable, and the bulk density of the polymer slurry is less likely to decrease, so the batch yield tends to be favorable. From the viewpoint of stabilizing particle diameter and particle shape, n 3 ·d 5 / V is preferably 15.00 m 2 / s 3 or less, more preferably 12.00 m 2 / s 3 or less, still more preferably 10.00 m 2 / s 3 or less. From this viewpoint, n 3 ·d 5 / V is preferably 1.00 to 15.00 m 2 / s 3 , more preferably 1.50 to 12.00 m 2 / s 3 , still more preferably 2.00 to 10.00 m 2 / s 3 . In addition, when n 3 ·d 5 / V falls within the above range, the particle size distribution of the obtained copolymer powder becomes suitable, and the water permeation rate coefficient can be easily adjusted to a suitable range.

[0059] d / D and n 3 ·d 5 / V are adjusted to the above ranges, the particle size distribution tends to be narrow, and the present copolymer having a water permeation rate coefficient of 1.0×10 -5 to 1.0×10 -3 g 2 / s can be easily obtained favorably.

[0060] <Molded Article> In one aspect, a molded article of the powder of the present disclosure described above is provided. The molded article is obtained by molding the powder of the present disclosure. Examples of the molded article include injection-molded articles, extrusion-molded articles, blow-molded articles, transfer-molded articles, press-molded articles, rotationally molded articles, compacted molded articles, and coating films obtained by electrostatic coating.

[0061] In one aspect, examples of the form of the molded article include pellets. A method for forming pellets includes using the powder of this disclosure as a molding material, extruding the molding material while melting it using a single-screw extruder, twin-screw extruder, or tandem extruder, and cutting it to a predetermined length to form pellets. The extrusion temperature from the extruder can be appropriately adjusted depending on the melt viscosity and manufacturing method of the copolymer, and is preferably between the melting point of the copolymer + 20°C and the melting point of the copolymer + 140°C. The extruded molded material can be cut using methods such as strand cutting, hot cutting, underwater cutting, and sheet cutting. The resulting pellets may be heated to remove volatile components (degassing). The resulting pellets may also be treated by contacting them with hot water at 30-200°C, steam at 100-200°C, or hot air at 40-200°C.

[0062] In molded articles (pellets, etc.), the total number of functional groups selected from the group consisting of -CF=CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2, and -CH2OH (hereinafter also referred to as "specific functional groups") (hereinafter also referred to as "number of specific functional groups") is such that the main chain of this copolymer has 10 carbon atoms. 6 The number of specific functional groups per unit is preferably 200 or less, more preferably 100 or less, even more preferably 50 or less, particularly preferably 10 or less, and extremely preferably 6 or less. By keeping the number of specific functional groups below the above upper limit, decomposition from terminal functional groups is suppressed, thus improving the heat resistance of the molded article. Furthermore, since the corrosiveness of metals due to decomposition products from terminal functional groups is also suppressed, the amount of metal contamination in the molded article due to melt molding tends to be reduced. While a small number of specific functional groups is preferable, a main chain with 10 carbon atoms is preferable. 6 Each item can contain one or more, two or more, or three or more.

[0063] Specific functional groups are functional groups present at the ends of the main chain or side chains of the copolymer, and functional groups present in the main chain or side chains. Specific functional groups are introduced into the copolymer, for example, by the chain transfer agent or polymerization initiator used in its production. More specifically, for example, if an alcohol is used as the chain transfer agent, or if a peroxide having the structure -CH2OH is used as the polymerization initiator, -CH2OH is introduced to the ends of the main chain of the copolymer. Furthermore, specific functional groups can also be introduced to the ends of the side chains of the copolymer by polymerizing monomers containing functional groups.

[0064] The types and number of functional groups in this copolymer can be determined by infrared spectroscopy. 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 (FT-IR) to obtain the infrared absorption spectrum of the copolymer. Separately, an infrared absorption spectrum (base spectrum) is obtained from a completely fluorinated copolymer that does not contain specific functional groups, and the difference spectrum between the infrared absorption spectrum and the base spectrum of the copolymer is obtained. From the absorption peak of the specific functional group appearing in this difference spectrum, the number of carbon atoms in the main chain of the copolymer (10) is determined according to the following formula (A). 6 Calculate the number of functional units N per individual.

[0065] N = I × K / t (A) I: Absorbance K: Correction coefficient t: Film thickness (mm)

[0066] Table 1 shows the absorption frequency, molar extinction coefficient, and correction factor for specific functional groups. The molar extinction coefficient of specific functional groups is determined from FT-IR (Fourier transform infrared spectroscopy) measurement data of low-molecular-weight model compounds.

[0067] [Table 1]

[0068] In this copolymer, the absorption frequencies of -CH2CF2H, -CH2COF, -CH2COOH, -CH2COOCH3, and -CH2CONH2 are obtained by subtracting several tens of Kaiser (cm) from the respective absorption frequencies of -CF2H, -COF, -COOH (free and bonded), -COOCH3, and -CONH2 shown in the table. -1 ) becomes lower. For example, the number of -COFs is such that the absorption frequency at 1883 cm⁻¹ is due to -CF2COF. -1 The number of functional groups determined from the absorption peak and the absorption frequency of 1840 cm² due to -CH2COF -1 This is the sum of the number of functional groups determined from the absorption peaks.

[0069] In one embodiment, the number of functional groups may be reduced by fluorinating the copolymer and converting specific functional groups to -CF3 terminal groups. The number of functional groups in the copolymer can be adjusted by changing the conditions of the fluorination treatment (treatment time, etc.). Fluorination treatment is carried out by contacting an unfluorinated copolymer with a fluorine-containing compound. Examples of fluorine-containing compounds include fluorine radical sources that generate fluorine radicals under fluorination treatment conditions. Examples of the above fluorine radical sources include F2 gas, N2F2, and halogenated fluorides (e.g., IF5 and ClF3).

[0070] The concentration of the fluorine radical source, such as F2 gas, may be 100% by volume. From a safety standpoint, it is preferable to use a mixed gas obtained by diluting F2 gas with an inert gas so that the concentration is 5 to 50% by volume (preferably 15 to 30% by volume). Examples of inert gases include nitrogen gas, helium gas, and argon gas, and from an economic standpoint, nitrogen gas is preferred.

[0071] The temperature during the fluorination treatment is preferably below the melting point of the copolymer, more preferably 20 to 240°C, and even more preferably 100 to 235°C. The fluorination treatment may also be carried out by contacting the copolymer in a molten state with a fluorine-containing compound.

[0072] The processing time for the fluorination treatment can be appropriately adjusted depending on the number of functional groups in the copolymer before fluorination, the desired number of functional groups, and the fluorination treatment method. For example, it is 0.5 to 30 hours, with 1 to 24 hours being preferred.

[0073] Specific methods for fluorination treatment include, for example, placing a shelf on which pellets are placed inside an oven, filling the oven with F2 gas or a mixed gas, and heating it for a certain period of time. Another method involves heating a flow-through column filled with pellets while simultaneously flowing F2 gas or a mixed gas through the column for a certain period of time.

[0074] In one embodiment, the molded article may be formed by molding the powder of the present disclosure into a shape having a specific function. The molded article may be further formed into a specific shape using the above-mentioned pellets as a molding material. Examples of molded products include nuts, bolts, fittings, films, bottles, gaskets, wire insulation materials, tubes, hoses, pipes, valves, seats, seals, packings, tanks, rollers, containers, cocks, connectors, filter housings, filter cages, flow meters, valves, pumps, wafer carriers, wafer boxes, and the like.

[0075] The molded products can be used for the following applications, for example: Food packaging films, lining materials, packings, seals, and sheets for fluid transfer lines used in food manufacturing processes, and other fluid transfer components for food manufacturing equipment; chemical stoppers, packaging films, lining materials, packings, seals, and sheets for fluid transfer lines used in pharmaceutical manufacturing processes, and other chemical liquid transfer components; internal lining components for chemical liquid tanks and piping in chemical plants or semiconductor factories; O-rings, tubes, packings, valve cores, hoses, seals, etc. used in automobile fuel systems and peripheral equipment, and fuel transfer components such as hoses and seals used in automobile automatic transmission systems; flange gaskets, shaft seals, valve stem seals, seals, and hoses for carburetors used in automobile engines and peripheral equipment, and other automobile components such as brake hoses, air conditioning hoses, radiator hoses, and wire insulation materials; and semiconductors such as O-rings, tubes, packings, valve cores, hoses, seals, rolls, gaskets, diaphragms, and fittings for semiconductor manufacturing equipment. Examples include chemical liquid transfer components for equipment; paint and ink components such as paint rolls, hoses, tubes, and ink containers for painting equipment; food and beverage transfer components such as tubes or hoses, belts, gaskets, and fittings for food and beverages, food packaging materials, and glass cooking equipment; waste liquid transport components such as tubes and hoses for waste liquid transport; high-temperature liquid transport components such as tubes and hoses for high-temperature liquid transport; steam piping components such as tubes and hoses for steam piping; corrosion-resistant tapes for piping such as tapes wrapped around piping on ship decks, etc.; various coating materials such as wire coating materials, optical fiber coating materials, transparent surface coating materials and backing materials provided on the light incident side surface of photovoltaic elements of solar cells; sliding components such as diaphragms and various gaskets for diaphragm pumps; agricultural films, fuel cell carrier films, and weather-resistant covers for various roofing materials and side walls, etc.; interior materials used in the construction field, and coating materials for glass such as non-combustible fire-resistant safety glass; and lining materials such as laminated steel sheets used in the home appliance field, etc.

[0076] In one embodiment, the molded article can be suitably used as a piping component (e.g., pipes, fittings, gaskets and packings), tube, or film for transferring fluids. The molded article can be suitably used, for example, as a chemical liquid transfer component for semiconductor devices.

[0077] In one embodiment, the molded body can be suitably used as a wire covering material. A specific example of its use is a covered wire comprising a core wire and a covering layer provided around the core wire, the covering layer being made of a molded body using the powder of this disclosure. A covered wire having a covering layer made of a molded body using the powder of this disclosure has excellent electrical properties because the core wire is resistant to corrosion and the outer diameter hardly changes, and can be suitably used as a high-frequency transmission cable, flat cable, heat-resistant cable, etc.

[0078] In one embodiment, the molded body can be suitably used as a compressible member. The compressible member is a member used in a compressed and deformed state, and its size and shape are appropriately set according to the application. The shape of the compressible member may be, for example, annular. The compressible member may also have a circular, oval, or rounded-corner quadrilateral shape in plan view, and may have a through hole in its center. The compressible member can be suitably used as a piping member for transferring fluids. Furthermore, the compressible member can be used as a component for constructing a non-aqueous electrolyte battery, and is particularly suitable as a component used in contact with the non-aqueous electrolyte in a non-aqueous electrolyte battery. The compressible member can also be suitably used as a sealing member such as a sealing gasket and sealing packing, and as an insulating member such as an insulating gasket and insulating packing. A sealing member is a member used to prevent leakage of liquid or gas, or intrusion of liquid or gas from the outside. An insulating member is a member used to insulate electricity. The compressible member may also be a member used for both sealing and insulating purposes.

[0079] In one embodiment, the molded article can be suitably used as a semiconductor component (e.g., tube, valve, union, solenoid valve, sensor, etc.). In particular, molded articles formed from fluorinated powder or pellets have stabilized unstable terminal functional groups. This suppresses the generation of impurities such as fluoride ions. Therefore, molded articles formed from fluorinated powder or pellets are particularly suitable as semiconductor components. [Examples]

[0080] The embodiments of this disclosure will now be described in detail with reference to examples, but the embodiments of this disclosure are not limited to these examples. In the following examples, Examples 1 to 8 are examples, and Examples 9 to 12 are comparative examples.

[0081] The abbreviations for each compound are as follows: TFE: Tetrafluoroethylene PPVE: Perfluoro(propyl vinyl ether) HFP: Hexafluoropropylene MeOH: methanol tBuOH: tert-butyl alcohol PFB: Heptafluorobutyroyl peroxide AE-3000 (Product name, manufactured by AGC Corporation; 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether; CF3CH2OCF2CF2H)

[0082] The various measurement methods are as follows:

[0083] (Content of each monomer unit) The content (mass%) of each unit in the copolymer contained in the powder obtained in each example is: 19 The molar ratio was calculated using a 1F nuclear magnetic resonance spectrometer (AVANCE-III-HD400, manufactured by Bruker Biospin), and the calculated molar ratio was then converted to mass ratio from the chemical structural formulas of each unit.

[0084] (MFR (Melt Flow Rate)) For each example, a melt flow tester (Shimadzu Corporation "CFT-500EX") was used to measure the mass (g) of the molding material flowing out of an orifice with a diameter of 2.095 mm and a length of 8 mm in 10 minutes, in accordance with ASTM D1238, under conditions of a temperature of 372°C and a load of 5 kg. This was defined as MFR (g / 10 min).

[0085] (Number of functional groups) The number of functional groups in the powders obtained in each example was measured using the method described above.

[0086] [Example 1] A polymerization tank (125 mm diameter) equipped with a stirrer (helical ribbon blade, blade diameter 116 mm) with an internal volume of 2.5 L was degassed, and then 1164 g of AE-3000, 668 g of water, 67 g of tBuOH, and 156 g of PPVE were charged into the polymerization tank. The mixed solvent of AE-3000, water, and tBuOH was separated into two phases at 25°C. Next, the temperature inside the polymerization tank was raised to 50°C (polymerization temperature), and 268 g of TFE and 67 g of propane (chain transfer agent) were further charged, raising the pressure inside the polymerization tank to 1.76 MPa (gauge pressure). The rotation speed of the stirring blade was set to 300 rpm, and 3.2 mL of a 0.06 mass% AE-3000 solution of PFB was charged as a polymerization initiator solution to start polymerization, and thereafter the above polymerization initiator solution was continuously added. Furthermore, TFE was continuously added to ensure that the pressure during polymerization was maintained at the same level as the pressure at the start of polymerization. After 314 minutes from the start of polymerization, 76.6 mL of polymerization initiator solution was added, and 250 g of TFE was added. At this point, the temperature inside the polymerization vessel was lowered to 23°C, and the vessel was purged until the pressure inside the polymerization vessel reached 1 atm.

[0087] The obtained copolymer slurry was filtered to separate the polymerization medium, and then dried at 150°C for 15 hours to obtain copolymer 1 powder. Based on the results of melt NMR and infrared absorption spectroscopy, the composition of copolymer 1 was TFE units / PPVE units = 96.5 / 3.5 (mass%). The MFR was 14 g / 10 min. The number of terminal groups determined from IR was 9 / 10 6 It was a single individual.

[0088] [Example 2] A polymerization tank (250 mm diameter) equipped with a 20 L internal volume stirrer (helical ribbon blade, blade diameter 232 mm) was degassed, and then 9314 g of AE-3000, 5344 g of water, 536 g of tBuOH, and 1248 g of PPVE were charged into the polymerization tank. The mixed solvent of AE-3000, water, and tBuOH was separated into two phases at 25°C. Next, the temperature inside the polymerization tank was raised to 50°C (polymerization temperature), and 2255 g of TFE and 536 g of propane (chain transfer agent) were further charged, raising the pressure inside the polymerization tank to 1.88 MPa (gauge pressure). The rotation speed of the stirring blade was set to 300 rpm, and 29.2 mL of a 0.06 mass% AE-3000 solution of PFB was charged as a polymerization initiator solution to start polymerization, and thereafter the above polymerization initiator solution was continuously added. Furthermore, TFE was continuously charged to ensure that the pressure during polymerization was maintained at the same level as the pressure at the start of polymerization. After 314 minutes from the start of polymerization, 628.4 mL of polymerization initiator solution was added, and 2000 g of TFE was charged. At this point, the temperature inside the polymerization vessel was lowered to 23°C, and the vessel was purged until the pressure inside the polymerization vessel reached 1 atm.

[0089] The obtained copolymer slurry was filtered to separate the polymerization medium, and then dried at 150°C for 15 hours to obtain copolymer 2 powder. Based on the results of melt NMR and infrared absorption spectroscopy, the composition of copolymer 2 was TFE units / PPVE units = 96.4 / 3.6 (mass%). The MFR was 15 g / 10 min. The number of terminal groups determined from IR was 9 / 10 6 It was a single individual.

[0090] [Example 3] Polymerization was carried out in the same manner as in Example 2, except that the rotation speed of the stirring blade was changed to 450 rpm. The polymerization time was 305 minutes.

[0091] The obtained copolymer slurry was filtered to separate the polymerization medium, and then dried at 150°C for 15 hours to obtain copolymer 3 powder. Based on the results of melt NMR and infrared absorption spectroscopy, the composition of copolymer 3 was determined to be TFE units / PPVE units = 96.4 / 3.6 (mass%). The MFR was 15 g / 10 min. The number of terminal groups determined from IR was 9 / 10 6 It was a single individual.

[0092] [Example 4] Polymerization was carried out in the same manner as in Example 1, except that the amount of PPVE, TFE, propane, and initial polymerization initiator solution added to the polymerization tank initially was changed to 101 g, 278 g, 70.8 g, and 2.8 mL, and the amount of polymerization initiator solution added continuously was changed to 68.9 mL. The polymerization time was 288 minutes.

[0093] The obtained copolymer slurry was filtered to separate the polymerization medium, and then dried at 150°C for 15 hours to obtain copolymer 4 powder. Based on the results of melt NMR analysis and infrared absorption spectroscopy analysis, the composition of copolymer 4 was TFE units / PPVE units = 97.8 / 2.2 (mass%). The MFR was 12 g / 10 min. The number of terminal groups determined from IR was 10 / 10 6 It was a single individual.

[0094] [Example 5] Polymerization was carried out in the same manner as in Example 1, except that the amount of AE-3000 initially added to the polymerization tank was changed to 1046g, the amount of water to 643g, the amount of PPVE to 274g, the amount of TFE to 248g, the amount of propane to 46.6g, and the amount of initial polymerization initiator solution to 4.2mL, and the amount of polymerization initiator solution added continuously was changed to 91.9mL. The polymerization time was 449 minutes.

[0095] The obtained copolymer slurry was filtered to separate the polymerization medium, and then dried at 150°C for 15 hours to obtain copolymer 5 powder. Based on the results of melt NMR analysis and infrared absorption spectroscopy analysis, the composition of copolymer 5 was TFE units / PPVE units = 93.3 / 6.7 (mass%). The MFR was 15 g / 10 min. The number of terminal groups determined from IR was 15 / 10 6 It was a single individual.

[0096] [Example 6] Polymerization was carried out in the same manner as in Example 1, except that the amount of PPVE initially added to the polymerization tank was changed to 159g and the amount of propane to 39.9g. The polymerization time was 313 minutes.

[0097] The obtained copolymer slurry was filtered to separate the polymerization medium, and then dried at 150°C for 15 hours to obtain copolymer 6 powder. Based on the results of melt NMR and infrared absorption spectroscopy, the composition of copolymer 6 was determined to be TFE units / PPVE units = 96.4 / 3.6 (mass%). The MFR was 2 g / 10 min. The number of terminal groups determined from IR was 7 / 10 6 It was a single individual.

[0098] [Example 7] Polymerization was carried out in the same manner as in Example 1, except that the amount of PPVE initially added to the polymerization tank was changed to 173g and the amount of propane to 92.1g. The polymerization time was 398 minutes.

[0099] The obtained copolymer slurry was filtered to separate the polymerization medium, and then dried at 150°C for 15 hours to obtain copolymer 7 powder. Based on the results of melt NMR analysis and infrared absorption spectroscopy analysis, the composition of copolymer 7 was TFE units / PPVE units = 96.1 / 3.9 (mass%). The MFR was 36 g / 10 min. The number of terminal groups determined from IR was 15 / 10 6 It was a single individual.

[0100] [Example 8] A polymerization tank (125 mm diameter) equipped with a stirrer (helical ribbon blade, blade diameter 116 mm) with an internal volume of 2.5 L was degassed, and 1381 g of AE-3000, 172 g of water, 50 g of tBuOH, 137 g of PPVE, and 4.7 mL of a 0.06 mass% AE-3000 solution of PFB as a polymerization initiator solution were charged into the reaction vessel. The gas phase was degassed under reduced pressure while the reaction vessel was cooled in an ice bath. The mixed solvent of AE-3000, water, and tBuOH separated into two phases at 25°C. While stirring at a rotational speed of 300 rpm, 164 g of HFP, 295 g of TFE, and 50.5 g of propane were injected into the reaction vessel under pressure, and the liquid phase temperature was raised to 50°C to start solution polymerization. The internal pressure of the reaction vessel was 1.41 MPa, which was used as the initial pressure. Thereafter, the polymerization initiator solution was continuously added. Furthermore, TFE was continuously added to ensure that the pressure during polymerization was maintained at the same level as the pressure at the start of polymerization. After 418 minutes from the start of polymerization, 91.9 mL of polymerization initiator solution was added, and 250 g of TFE was added. At this point, the temperature inside the polymerization vessel was lowered to 23°C, and the vessel was purged until the pressure inside the polymerization vessel reached 1 atm.

[0101] The obtained copolymer slurry was filtered to separate the polymerization medium, and then dried at 150°C for 15 hours to obtain copolymer 8 powder. Based on the results of melt NMR analysis and infrared absorption spectroscopy analysis, the composition of copolymer 8 was TFE units / HFP units / PPVE units = 94.4 / 1.2 / 4.4 (mass%). The MFR was 13 g / 10 min. The number of terminal groups determined from IR was 13 / 10 6 It was a single individual.

[0102] [Example 9] Polymerization was carried out in the same manner as in Example 1, except that the rotation speed of the stirring blade was set to 200 rpm. The polymerization time was 330 minutes.

[0103] The obtained copolymer slurry was filtered to separate the polymerization medium, and then dried at 150°C for 15 hours to obtain copolymer 9 powder. Based on the results of melt NMR analysis and infrared absorption spectroscopy analysis, the composition of copolymer 9 was TFE units / PPVE units = 96.5 / 3.5 (mol%). The MFR was 14 g / 10 min. The number of terminal groups determined from IR was 10 / 10 6 It was a single individual.

[0104] [Example 10] Polymerization was carried out in the same manner as in Example 1, except that the amount of tBuOH added was set to 0 g and the chain transfer agent was changed from propane to 36.6 g of MeOH. The polymerization time was 320 minutes.

[0105] The obtained copolymer slurry was filtered to separate the polymerization medium, and then dried at 150°C for 15 hours to obtain copolymer 10 powder. Based on the results of melt NMR and infrared absorption spectroscopy, the composition of copolymer 10 was TFE units / PPVE units = 96.5 / 3.5 (mol%). The MFR was 14 g / 10 min. The number of terminal groups determined from IR was 38 / 10 6 It was a single individual.

[0106] [Example 11] Polymerization was carried out in the same manner as in Example 8, except that the rotation speed of the stirring blade was set to 200 rpm. The polymerization time was 425 minutes.

[0107] The obtained copolymer slurry was filtered to separate the polymerization medium, and then dried at 150°C for 15 hours to obtain copolymer 11 powder. Based on the results of melt NMR analysis and infrared absorption spectroscopy analysis, the composition of copolymer 11 was TFE units / HFP units / PPVE units = 94.4 / 1.2 / 4.4 (mass%). The MFR was 13 g / 10 min. The number of terminal groups determined from IR was 12 / 10 6 It was a single individual.

[0108] [Example 12] Polymerization was carried out in the same manner as in Example 8, except that the amount of tBuOH added was set to 0 g and the chain transfer agent was changed from propane to 26.2 g of MeOH. The polymerization time was 411 minutes.

[0109] The obtained copolymer slurry was filtered to separate the polymerization medium, and then dried at 150°C for 15 hours to obtain copolymer 12 powder. Based on the results of melt NMR analysis and infrared absorption spectroscopy analysis, the composition of copolymer 12 was TFE units / HFP units / PPVE units = 94.4 / 1.2 / 4.4 (mass%). The MFR was 13 g / 10 min. The number of terminal groups determined from IR was 44 / 10 6 It was a single individual.

[0110] (Moisture permeability coefficient) The water penetration rate coefficient of each obtained copolymer powder was determined using a PNT-N penetrometer (Hosokawa Micron Corporation). The powder was placed in a cell equipped with filter paper on the bottom, and the bottom of the cell was immersed in water at 36°C. The mass of water penetrating the powder was measured as W L (g) The time required for infiltration was denoted as t(s), and the water infiltration rate coefficient was calculated using the following equation (1). Measurements were performed with n=3 for each sample, and the average value was taken as the measured water infiltration rate coefficient for each sample. Equation (1): Moisture permeation rate coefficient = W L 2 / t

[0111] (Drying test) 250g of each copolymer powder was placed in a 2L beaker, 1L of water was added, and the mixture was stirred at 100rpm for 10 minutes. The resulting slurry was filtered at atmospheric pressure using Advantec No. 1 filter paper to obtain each copolymer powder moistened with water. This powder was placed in a 10cm x 20cm SUS304 tray and set on a hot plate placed on a scale. The hot plate was set to 150°C, and the time until mass loss due to water evaporation ceased was measured. The experiment was conducted in a constant temperature and humidity chamber at 25°C and 60% humidity. The measurement results were judged according to the following criteria. • Time until mass loss ceases is less than 1.5 hours: A • Time until mass loss ceases: 1.5 hours or more but less than 2 hours: B • Time until mass loss ceases: 2 hours or more: C

[0112] Tables 2 and 3 show the polymerization conditions, copolymer composition, MFR, number of functional groups, water penetration rate coefficient, and drying test results for each example. In the tables, "TFE," "PPVE," and "HFP" indicate the content (mass %) of each unit relative to the total units contained in the copolymer. d / D and n 3 ·d 5 / V is calculated with d[m] being the maximum diameter of the impeller, D[m] being the inner diameter of the reaction vessel, and n[s] being the rotation speed of the impeller per second. -1 ], the volume of the reaction vessel is V[m³ 3 These are the calculated values ​​when ] is used.

[0113] [Table 2]

[0114] [Table 3]

[0115] Based on the above results, the water permeation rate coefficient is 1.0 × 10 -5 ~1.0×10 -3 It was found that copolymer powders within this range are suitable for the drying process. In particular, when comparing Examples 1, 4-7, and 6, where the stirring conditions were the same, the drying test results were especially excellent in Examples 1 and 6, where the PPVE content was within a moderate range and the MFR was relatively low.

Claims

1. A powder mainly composed of a copolymer containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether), wherein the moisture penetration rate coefficient of the powder is 1.0 × 10 －５ ~1.0 x 10 －３ g ２ A powder that is / s.

2. The powder according to claim 1, wherein the content of the tetrafluoroethylene-based units is 92.0 to 98.0% by mass relative to the total monomer units of the copolymer.

3. The powder according to claim 1, wherein the proportion of the units based on the perfluoro(alkyl vinyl ether) is 2.0 to 8.0% by mass with respect to the total monomer units of the copolymer.

4. The powder according to claim 1, wherein the melt flow rate measured at 372°C in accordance with ASTM D1238 is 1.0 to 40.0 g / 10 min.

5. The powder according to claim 1, wherein the unit based on perfluoro(alkyl vinyl ether) includes a unit based on perfluoro(propyl vinyl ether).

6. A molded powder body according to any one of claims 1 to 5.

7. The process involves polymerizing tetrafluoroethylene and perfluoro(alkyl vinyl ether) in a polymerization medium in a reaction vessel equipped with helical ribbon blades as stirring blades, in the presence of a radical initiator and a chain transfer agent, to produce a copolymer powder containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether). The radical initiator is diacyl peroxide, The chain transfer agent is an organic compound having 3 to 12 carbon atoms, consisting of at least one atom selected from the group consisting of hydrogen atoms, fluorine atoms, and chlorine atoms, and only carbon atoms. The polymerization medium comprises water, a nonionic fluorine-containing organic compound, and an alcohol, and separates into two phases at 25°C. The aforementioned alcohol does not have a methylene hydrogen atom, a methine hydrogen atom, or a methyl hydrogen atom adjacent to a heteroatom. When the maximum diameter of the stirring blade is d [m], the inner diameter of the reaction vessel is D [m], and the rotation speed of the stirring blade per second is n [s －１ , the volume of the reaction vessel is V [m ３ , d / D is 0.90 or more, and n ３ ・d ５ / V is 1.00 to 15.00 m ２ / s ３ , which is a method for producing powder.

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