Powder, compact, and method for manufacturing powder

Abstract

The present invention provides a PFA powder that can reduce the load on piping during transportation, a molded product obtained from the powder, and a method for producing the powder. [Solution] The present invention provides a powder whose main component is a copolymer containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether), wherein the powder has an angle of repose of 37 to 43 degrees, a collapse angle of 24 to 31 degrees, and a difference angle of 10 to 16 degrees; a molded body obtained from the powder; and a method for producing the powder.

Description

[Technical Field]

[0001] The present disclosure relates to powders, compacts, and methods for producing powders. [Background technology]

[0002] Copolymers of tetrafluoroethylene and perfluoro(alkyl vinyl ether) (hereinafter referred to as "PFA") are known as melt-processable fluororesins that have excellent mechanical, chemical, and electrical properties. PFA is used in a variety of applications, including semiconductor components, automotive components, various coating materials, and various packaging materials.

[0003] Patent Document 1 describes a modified polytetrafluoroethylene granular powder obtained by granulating a modified polytetrafluoroethylene powder obtained by copolymerizing tetrafluoroethylene and perfluorovinyl ether, and having a charge amount, angle of repose, apparent density, etc. within specific ranges. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-259252 Summary of the Invention [Problem to be solved by the invention]

[0005] In the field of semiconductor manufacturing, as circuit patterns become increasingly finer and more highly integrated, the threshold size for pattern defects continues to shrink. One cause of defects is the unintentional introduction of impurities into the semiconductor manufacturing process. The materials and components used in semiconductor manufacturing equipment are also sources of impurities. When manufacturing PFA for semiconductor manufacturing equipment, the resulting PFA powder is often transported through sealed pipes lined with resin to prevent the introduction of foreign matter and increase cleanliness. However, resin linings are prone to deterioration, such as peeling, due to repeated pressure changes within the pipes. Therefore, attempts to increase the cleanliness of PFA can easily degrade the manufacturing equipment.

[0006] The inventors attempted to develop a PFA powder that can reduce the load on piping during transportation in order to reduce deterioration of manufacturing equipment. The present disclosure relates to a PFA powder that can reduce the load on piping during transportation, a molded body obtained from the powder, and a method for manufacturing the powder. [Means for solving the problem]

[0007] Means for solving the above problems include the following aspects. <1> A powder whose main component is a copolymer containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether), wherein the powder has an angle of repose of 37 to 43 degrees, a collapse angle of 24 to 31 degrees, and a difference angle of 10 to 16 degrees. <2> the content of the units based on tetrafluoroethylene is 92.0 to 98.0 mass% based on the total monomer units of the copolymer; <1> The powder described in <3> the proportion of units based on the perfluoro(alkyl vinyl ether) is 2.0 to 8.0 mass% based on the total monomer units of the copolymer; <1> or <2> The powder described in <4> A melt flow rate of 1.0 to 40.0 g / 10 min measured at 372°C in accordance with ASTM D1238. <1> ~ <3> The powder according to any one of the preceding claims. <5> the perfluoro(alkyl vinyl ether)-based units include perfluoro(propyl vinyl ether)-based units; <1> ~ <4> The powder according to any one of the preceding claims. <6> <1> ~ <5> A molded product of the powder according to any one of claims 1 to 10. <7> The method comprises polymerizing tetrafluoroethylene and perfluoro(alkyl vinyl ether) in a polymerization medium in the presence of a radical initiator in a reaction vessel equipped with a helical ribbon impeller as an agitator, to produce a copolymer powder containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether); the radical initiator comprises an organic peroxide; the polymerization medium comprises water, a nonionic fluorine-containing organic compound, and an alcohol, and separates into two phases at 25°C; 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 1.00m 2 / s 3 This completes the method for producing the powder. [Effects of the Invention]

[0008] According to the present disclosure, there are provided a PFA powder that can reduce the load on piping during transportation, a molded body obtained from the powder, and a method for producing the powder. DETAILED DESCRIPTION OF THE INVENTION

[0009] 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, components (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values ​​and their ranges, and they do not limit the embodiments of the present disclosure.

[0010] In the present disclosure, the term "process" includes not only a process that is independent of other processes, but also a process that cannot be clearly distinguished from other processes as long as the purpose of the process is achieved. In the present disclosure, numerical ranges indicated using "to" include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples. In the present disclosure, each component may contain multiple substances corresponding to the component. When multiple substances 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 substances present in the composition, unless otherwise specified. In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In the present disclosure, a "polymer" is a compound formed by polymerizing monomers, i.e., a "polymer" has a plurality of structural units. In the present disclosure, a "copolymer" is a compound obtained by copolymerizing two or more types of 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 may or may not further contain other monomers. In the present disclosure, the term "unit" of a polymer refers collectively to an atomic group derived from one molecule of the monomer formed directly by polymerization of the monomer, and an atomic group obtained by chemically converting a part of the atomic group. Hereinafter, in some cases, a unit derived from an individual monomer will be referred to by the name of the monomer followed by "unit." The angle of repose, angle of collapse, and angle of difference of the powder in the present disclosure are values ​​measured at a temperature of 25°C and a humidity of 50% RH.

[0011] <Powder> The powder of the present disclosure is a powder whose main component is a copolymer containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether), and the powder has an angle of repose of 37 to 43 degrees, a collapse angle of 24 to 31 degrees, and a difference angle of 10 to 16 degrees. Hereinafter, a copolymer containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether) will also be referred to as "the copolymer," the units based on tetrafluoroethylene will also be referred to as "TFE units," and the units based on perfluoro(alkyl vinyl ether) will also be referred to as "PAVE units." The "major component" of a powder refers to a component that accounts for 50% by mass or more of the powder.

[0012] The powder of the present disclosure can reduce the load on the piping during transportation by having the angle of repose, angle of collapse, and angle of difference within specific ranges. When the angle of repose is 37 to 43 degrees, the powder's fluidity and jettability tend to be well balanced. When the angle of collapse is 24 to 31 degrees, the powder's cohesion tends to be low and it is easy to handle. When the angle of difference is 10 to 16 degrees, the powder's fluidity and jettability tend to be well balanced. Powders that satisfy these properties can be transported with low pressure during transportation in piping, and are less likely to cause deterioration of, for example, the resin lining inside the piping.

[0013] The powder of the present disclosure contains the present copolymer as a main component, i.e., contains 50% by mass or more of the present copolymer. The powder of the present disclosure may contain 60% by mass or more of the present copolymer, 70% by mass or more, 80% by mass or more, 90% by mass or more of the present copolymer, or may contain only the present copolymer.

[0014] The repose angle of the powder is 37 to 43 degrees. The repose angle of the powder may be 38 degrees or more, or 39 degrees or more. The repose angle of the powder may be 42 degrees or less, or 41 degrees or less. When the repose angle is the upper limit or less, the powder has high fluidity and the load on the piping during transportation is easily reduced. When the repose angle is the lower limit or more, flashing of the powder is easily suppressed.

[0015] The angle of repose can be adjusted by the polymerization medium, stirring conditions, etc., used when polymerizing the copolymer. For example, if the polymerization medium contains water, a nonionic fluorine-containing organic compound, and an alcohol and separates into two phases at 25°C, the particle size distribution of the powder will be narrow, and the angle of repose will likely be small. In addition, the angle of repose will likely be small if the stirring conditions in the reaction vessel (reactor volume, stirring blade diameter, rotation speed, etc.) are set to strong stirring conditions.

[0016] The collapse angle of the powder is 24 to 31 degrees. The collapse angle of the powder may be 25 degrees or more, or 26 degrees or more. The collapse angle of the powder may be 30 degrees or less, or 29 degrees or less. When the collapse angle is equal to or less than the upper limit, the powder has low cohesion, which makes it easy to reduce the load on piping during transportation. When the collapse angle is equal to or more than the lower limit, the powder is moderately cohesive and scatters little, resulting in excellent handleability.

[0017] The collapse angle can be adjusted by the polymerization medium, stirring conditions, etc., used when polymerizing the copolymer. For example, if the polymerization medium contains water, a nonionic fluorine-containing organic compound, and an alcohol and separates into two phases at 25°C, the powder will have a high circularity and the collapse angle will tend to be small. In addition, the collapse angle will tend to be small by setting the stirring conditions in the reaction vessel (reactor volume, stirring blade diameter, rotation speed, etc.) to strong stirring conditions.

[0018] The difference angle of the powder is 10 to 16 degrees. The difference angle of the powder may be 11 degrees or more, or 12 degrees or more. The difference angle of the powder may be 15 degrees or less, or 14 degrees or less. When the difference angle is equal to or greater than the lower limit, the powder has good fluidity and the load on the piping during transportation is easily reduced. When the difference angle is equal to or less than the upper limit, the pourability is appropriate.

[0019] The difference angle can be adjusted by the polymerization medium, stirring conditions, etc., used when polymerizing the copolymer. For example, if the polymerization medium contains water, a nonionic fluorine-containing organic compound, and an alcohol and separates into two phases at 25°C, the powder will have a high circularity and the difference angle will tend to be large. In addition, the difference angle will tend to be large if the stirring conditions in the reaction vessel (reactor volume, stirring blade diameter, rotation speed, etc.) are set to strong stirring conditions.

[0020] The angle of repose, angle of collapse, and difference angle of a powder are measured using a powder property measuring instrument (e.g., Multitester MT-02, Seishin Enterprise Co., Ltd.) at a temperature of 25°C and a humidity of 50% RH by the injection method. For example, powder is poured vertically using a funnel toward the center of a circular horizontal plate with a diameter of 80 mm, forming a cone-shaped powder on the plate. The powder is poured until the cone maintains its shape, and the angle of repose is measured using a protractor. Next, a 109 g weight placed on the same base as the horizontal plate is dropped three times from a height of 160 mm. After some of the powder disintegrates and falls off due to the impact, the angle of collapse is measured using a protractor. The difference angle is calculated as the difference between the angle of repose and the angle of collapse (angle of repose - angle of collapse).

[0021] The average particle size of the powder is preferably 0.01 μm or more, more preferably 0.05 μm or more, and even more preferably 0.1 μm or more. The average particle size of the powder is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less. The average particle size is measured using a laser diffraction / scattering particle size distribution analyzer (for example, the LA-960V2 manufactured by Horiba, Ltd.). Specifically, the average particle size is obtained by a wet measurement method in which the sample to be measured is dispersed in an isopropanol solvent and the average particle size of the dispersed sample is measured.

[0022] The circularity of the powder is preferably 0.30 or more, more preferably 0.40 or more, and even more preferably 0.50 or more. The upper limit of the circularity of the powder is 1. The circularity can be determined by dispersing the sample to be measured in an isopropanol solvent, performing image analysis of the particle shape using a particle shape image analyzer (PITA-04M, manufactured by Seishin Enterprise Co., Ltd.), and using the following formula (1): Formula (1): Circularity = 4πS / L 2 S: Projected area L: Perimeter length When the average particle size and circularity of the powder are within the above ranges, the angle of repose, angle of collapse, and angle of difference of the powder can be easily adjusted to fall within suitable ranges.

[0023] 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 increasing the fluidity during melting and improving moldability, and from the viewpoint of improving the low-speed tear strength of the molded article. To facilitate improvement in 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, and even more preferably 30.0 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 for adjusting the MFR of the powder within the above range is to adjust the molecular weight of the present copolymer. The higher the molecular weight of the present copolymer, the smaller the MFR. MFR refers to the mass (g) of a melt that flows from an orifice with a diameter of 2.095 mm and a length of 8 mm in 10 minutes, measured at a temperature of 372°C under a load of 5 kg in accordance with ASTM D1238. The copolymer and other components are described in detail below.

[0024] [This copolymer] The copolymer contains TFE units and PAVE units.

[0025] The content of TFE units is not particularly limited. From the viewpoint of increasing the strength of the molded article, the content of TFE units 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, based on all monomer units contained in the copolymer. From the viewpoint of increasing the flexibility of the molded article, the content of TFE units 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, based on all monomer units contained in the copolymer. From this viewpoint, the content of TFE units 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, based on all monomer units contained in the copolymer.

[0026] The content of PAVE units is not particularly limited. From the viewpoint of improving the flexibility of the molded article, the content of PAVE units 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, based on the total monomer units contained in the copolymer. From the viewpoint of improving the crystallinity of the copolymer and the strength of the molded article, the content of PAVE units 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, based on the total monomer units contained in the copolymer. From these viewpoints, the content of PAVE units is preferably 2.0 to 8.0% by mass, more preferably 2.5 to 7.5% by mass, 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, based on the total monomer units contained in the copolymer.

[0027] As the PAVE, a monomer represented by formula (1) is preferred. CF2=CF-O-Rf 1 (1) In formula (1), Rf 1 represents a perfluoroalkyl group having 1 to 10 carbon atoms. 1From the viewpoint of achieving better polymerization reactivity, the number of carbon atoms in the perfluoroalkyl group represented by the following formula is preferably 1 to 8, more preferably 1 to 6, even more preferably 1 to 5, and particularly preferably 1 to 3. The perfluoroalkyl group may be linear or branched.

[0028] Specific examples of PAVE include perfluoro(methyl vinyl ether) (PMVE), perfluoro(ethyl vinyl ether) (PEVE), and perfluoro(propyl vinyl ether) (PPVE), and PMVE or PPVE is preferred, with PPVE being more preferred, from the viewpoint of achieving an excellent balance between raw material cost and ease of handling during polymerization. PAVE may be used alone or in combination of two or more types.

[0029] In this copolymer, from the viewpoint of exhibiting the properties of the TFE units and PAVE units well and from the viewpoint of making the molded body less likely to deform easily by compression or tension, the total content of the TFE units and PAVE units is preferably 95.0 mass% or more, more preferably 98.0 mass% or more, even more preferably 99.0 mass% or more, and may be 100.0 mass% based on the total monomer units contained in this copolymer.

[0030] The present copolymer may or may not contain, in addition to the TFE units and PAVE units, units based on other monomers copolymerizable with TFE and PAVE. Other monomers include, for example, ethylene, vinylidene fluoride (VdF), hexafluoropropylene (HFP), CX 1 X 2 =CX 3 (CF2) 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 (In the formula, Rf 2represents 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 preferably 5.0 mass% or less, more preferably 2.0 mass% or less, and even more preferably 1.5 mass% or less, based on the total monomer units contained in the present copolymer.

[0031] When the copolymer contains units based on other monomers, it preferably contains TFE units, PAVE units, and HFP units. When the copolymer contains TFE units, PAVE units, and HFP units, the content of HFP units is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, based on the total monomer units contained in the copolymer. The content of HFP units is preferably 10.0% by mass or less, more preferably 5.0% by mass or less, based on the total monomer units contained in the copolymer.

[0032] From the viewpoint of exhibiting the properties of the TFE units and PAVE units well and of making the molded body less likely to deform easily under compression or tension, it is preferable that the present copolymer does not contain units based on the other monomers mentioned above and contains only TFE units and PAVE units.

[0033] The contents of TFE units, PAVE units, and units based on other monomers in this copolymer are as follows: 19 It can be measured by known methods such as F-NMR (nuclear magnetic resonance analysis).

[0034] From the viewpoint of excellent mechanical strength of the molded article, the melting point of the present 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 the present copolymer, the melting point of the present copolymer is preferably 310.5° C. or lower, more preferably 310.0° C. or lower, and even more preferably 309.5° C. or lower. The melting point of the present copolymer can be adjusted to fall within the above range by lowering the polymerization temperature during production of the present 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.

[0035] It is intended that the copolymers are not so-called elastomers. Elastomers are copolymers that do not have a melting point.

[0036] [Other ingredients] The powder may or may not contain components other than the present copolymer, for example, the powder may contain a resin other than the present copolymer, a heat stabilizer, an antioxidant, a colorant, an ultraviolet absorber, a filler, a crosslinking agent, a crosslinking aid, an organic peroxide, etc. When the powder contains components other than the present 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 present copolymer may be 0.0000001 parts by mass or more, 0.0000005 parts by mass or more, or even 0.000001 parts by mass or more, relative to the total amount of the powder. From this perspective, the total content of components other than the present copolymer may be 0.0000001 to 50 parts by mass, relative to the total amount of the powder.

[0037] [Metallic elements] From the viewpoint of suppressing the incorporation of metals into the compact, it is preferable that the amount of metal elements in the powder is suppressed. For example, 32 types of metal elements measurable by inductively coupled plasma mass spectrometry (ICP-MS) (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), lithium (Li), and the like can be detected. The total content of the elements (iron, manganese, molybdenum, nickel, potassium, sodium, rubidium, strontium, titanium, tin, vanadium, zinc, zirconium, zinc ...

[0038] The total content of the 32 metal elements 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 white smoke and dissolved in dilute nitric acid. The resulting solution is then analyzed using an inductively coupled plasma mass spectrometer (e.g., ICP-MS 7500cs (product name), manufactured by Agilent Technologies) to determine the total content of the 32 metal elements measured by the absolute calibration curve method.

[0039] The metal elements in the powder 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 to use, for example, a material with a low content of metal elements in the production of the copolymer. For example, it is preferable to use a polymerization medium (e.g., water) with a low content of metal elements (e.g., ultrapure water) as the polymerization medium when copolymerizing TFE and PAVE.

[0040] <Powder manufacturing method> The method for producing the powder of the present disclosure is not particularly limited. The method for producing the powder may include a step of producing the present copolymer (hereinafter also referred to as a "copolymer production step"). Examples of the copolymer production process include a process of producing the copolymer by using the above-mentioned monomers (TFE, PAVE, and other monomers as necessary) by a method such as bulk polymerization, solution polymerization, suspension polymerization, or emulsion polymerization, and a process of producing the copolymer by solution polymerization is preferred. In the production of the present copolymer, in addition to the above-mentioned monomers, a polymerization initiator, a polymerization medium, a chain transfer agent, an emulsifier, a pH adjuster, etc. may be used.

[0041] 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 a temperature of 20 to 90°C. Specific examples of the polymerization initiator include various polymerization initiators exemplified in WO 2013 / 015202. One type of polymerization initiator may be used alone, or two or more types may be used in combination. Specific examples of the radical initiator include azo-based radical initiators, peroxide-based radical initiators, etc. The radical initiators may be used alone or in combination of two or more. 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-cyclohexanecarbonitrile) (ACHN), dimethyl-2,2'-azobisisobutyrate (MAIB), 4,4'-azobis(4-cyanovaleric acid) (ACVA), 1,1'-azobis(1-acetoxy-1-phenylethane), 2,2'-azobis(2-methylbutyramide), 2,2' -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), 2,2'-azobis(N-cyclohexyl-2-methylpropionamide), and the like. Peroxide-based radical initiators include organic peroxides and inorganic peroxides. Examples of organic peroxides include peroxydicarbonates such as diisopropyl peroxydicarbonate; peroxyesters such as tert-butyl peroxypivalate, tert-butyl peroxyisobutyrate, and tert-butyl peroxyacetate; non-fluorine-based diacyl peroxides such as isobutyryl peroxide, octanoyl peroxide, benzoyl peroxide, and lauroyl peroxide; and (Z(CF2) p fluorine-containing diacyl peroxides (heptafluorobutyroyl peroxide, etc.) such as fluorocarbon diacyl peroxide (COO)2 (wherein Z is a hydrogen atom, a fluorine atom or a chlorine atom, and p is an integer of 1 to 10); perfluorotert-butyl peroxide, etc. Examples of inorganic peroxides include potassium persulfate, sodium persulfate, and ammonium persulfate. Organic peroxides are preferred from the viewpoints of high polymerization rate, resistance to coloration of the polymer when heated, and excellent heat resistance of the copolymer obtained. The amount of the polymerization initiator used is preferably 0.01 to 0.9 parts by mass, more preferably 0.03 to 0.5 parts by mass, based on 100 parts by mass of the amount of the monomer used.

[0042] The polymerization medium may be water, an organic solvent, or a mixed solvent of water and an organic solvent. One type of polymerization medium may be used alone, or two or more types may be used in combination.

[0043] As the water, deionized water is preferred, and ultrapure water is more preferred. From the viewpoint of easily obtaining the present copolymer having a low content of metal elements, the content of metal elements in water is preferably 2.0 ppm by mass or less, more preferably 1.0 ppm by mass or less, further preferably 0.5 ppm by mass or less, and particularly preferably 0.1 ppm by mass or less. The content of metal elements is preferably 0 ppb by mass or more. The method for achieving the above-mentioned metal element contents is not particularly limited, and examples thereof include a method for reducing the metal element content by filtering water through various filters. The content of metal elements in water can be measured by the absolute calibration curve method using ICP-MS, similar to the method for measuring the content of metal elements in powder described above. The electrical conductivity of water is preferably 1.00 μS / cm or less, 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 metal elements in the water, and the greater the amount of metal elements, the greater the electrical conductivity of the water. The electrical conductivity of water can be measured by a known measurement method.

[0044] Examples of the organic solvent include fluorine-containing organic compounds such as perfluorocarbons, hydrofluorocarbons and hydrofluoroethers, and alcohols.

[0045] The fluorine-containing organic compound is preferably a nonionic fluorine-containing organic compound. Examples of perfluorocarbons, which are nonionic fluorine-containing organic compounds, include n-perfluorohexane, n-perfluoroheptane, perfluorocyclobutane, perfluorocyclohexane, and perfluorobenzene. Examples of hydrofluorocarbons which are nonionic fluorine-containing organic 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 hydrofluoroethers, which are nonionic fluorine-containing organic compounds, include methoxynonafluorobutane (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), ethoxynonafluorobutane (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- Examples include 2,2,3,3-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 (CFCF(OCH)CF(CF)CF). From the viewpoint of polymerization reactivity, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether is preferred.

[0046] 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 have any of a methylene hydrogen atom, a methine hydrogen atom, or a methyl hydrogen atom adjacent to a heteroatom. A methylene hydrogen atom is a hydrogen atom of a methylene group (-CH2-), a methine hydrogen atom is a hydrogen atom of a methine group (-CH-), and a methyl hydrogen atom adjacent to a heteroatom is a hydrogen atom of a methyl group (-CH3) adjacent to a heteroatom.

[0047] The polymerization medium is preferably a mixed solvent containing water and a fluorine-based solvent, and from the viewpoint of easily controlling the angle of repose, angle of collapse, and difference angle within suitable ranges, a mixed solvent containing water, a fluorine-containing organic compound, and an alcohol is more preferred, and a mixed solvent containing water, a nonionic fluorine-containing organic compound, and an alcohol is even more preferred. From the viewpoints of suspension property and economy, the amount of the nonionic fluorine-containing organic compound used is preferably 10% by mass or more but less than 100% by mass, more preferably 50 to 90% by mass, based on the total mass of the mixed solvent. From the viewpoint of easily controlling the angle of repose, angle of collapse, and difference angle within suitable ranges, the amount of the alcohol used is preferably 1 to 10% by mass, more preferably 2 to 5% by mass, based on the total mass of the mixed solvent.

[0048] The amount of the polymerization medium used is preferably 3 times or more, more preferably 4 times or more, by mass, the amount of the monomer used. The amount of the polymerization medium used is preferably 20 times or less, more preferably 17 times or less, by mass, the amount of the monomer used. From this viewpoint, the amount of the polymerization medium used is preferably 3 to 20 times, more preferably 4 to 17 times, the amount of the monomer used.

[0049] As the chain transfer agent, from the viewpoint of having a large chain transfer constant and requiring only a small amount to be added, 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. Among these, from the viewpoint of a higher chain transfer constant and high stability of the terminal groups of the present 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 from the viewpoint of reactivity and easy availability, methanol is more preferred. One chain transfer agent may be used alone, or two or more may be used in combination. Note that a 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 the chain transfer agent used is preferably 0.001 times or more, more preferably 0.005 times or more, by mass ratio, relative to the amount of the monomer used. The amount of the chain transfer agent used is preferably 5 times or less, more preferably 4 times or less, by mass ratio, relative to the amount of the monomer used. From this viewpoint, the amount of the chain transfer agent used is preferably 0.001 to 5 times, more preferably 0.005 to 4 times, by mass ratio, relative to the amount of the monomer used.

[0050] As the compounds used in the 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 content of metal elements.

[0051] 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 15° C. or higher, the polymerizability can be excellent. When the polymerization temperature is 60° C. or lower, the melting point of the present copolymer can be improved. The polymerization pressure is preferably from 0.5 to 3.0 MPa, more preferably from 0.9 to 2.5 MPa. The polymerization time is preferably 1 to 12 hours.

[0052] 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.

[0053] In one embodiment, a method for producing a powder includes polymerizing TFE and PAVE in a polymerization medium in the presence of a radical initiator in a reaction vessel equipped with a helical ribbon impeller as an agitator, and producing a powder of the copolymer, wherein the radical initiator includes an organic peroxide, the polymerization medium includes water, a nonionic fluorine-containing organic compound, and an alcohol, and the polymerization medium separates into two phases at 25°C, and the maximum diameter of the agitator is d [m], the inner diameter of the reaction vessel is D [m], and the rotation speed of the agitator 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 1.00m 2 / s 3 That's all. Hereinafter, the method for producing powder in this embodiment will also be referred to as "production method A." Unless otherwise specified, the details of the powder production method for production method A are as described above.

[0054] In Production Method A, an organic peroxide is used as the radical initiator. Examples of the organic peroxide include the compounds described above. Organic peroxides are preferred because they have a high polymerization rate, are less likely to discolor when heated, and provide the resulting copolymer with excellent heat resistance.

[0055] In Production Method A, a polymerization medium containing water, a nonionic fluorine-containing organic compound, and an alcohol is used, which separates into two phases at 25°C. This polymerization medium is preferred because it combines the advantages of solution polymerization, which is less likely to cause scaling on the reactor walls, with suspension polymerization, which is advantageous in terms of heat removal and batch yield. Furthermore, the presence of alcohol changes the liquid properties, such as surface tension, and the powder's circularity and particle size distribution fall within appropriate ranges, making it easier to obtain a copolymer with an angle of repose of 37 to 43 degrees, a collapse angle of 24 to 31 degrees, and a difference angle of 10 to 16 degrees.

[0056] An example of a polymerization medium that contains water, a nonionic fluorine-containing organic compound, and an alcohol and 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.

[0057] In production method A, polymerization is carried out in a reaction vessel equipped with a helical ribbon impeller as an impeller. The maximum diameter of the impeller is d [m], the inner diameter of the reaction vessel is D [m], and the rotation speed of the impeller 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 1.00m 2 / s 3 That's all.

[0058] The helical ribbon impeller is a stirring impeller equipped with a spirally wound, band-shaped blade, and has excellent stirring power, making it easy to obtain a favorable polymerization rate and batch yield. The helical ribbon impeller may be a single helical ribbon impeller or a double helical ribbon impeller, with a double helical ribbon impeller being preferred from the viewpoint of superior stirring power. Furthermore, a strong shear force can be applied to the solution, making it possible to adjust the particle size, circularity, and particle size distribution of the powder, making it easy to preferably obtain the present copolymer having an angle of repose of 37 to 43 degrees, a collapse angle of 24 to 31 degrees, and a difference angle of 10 to 16 degrees.

[0059] The volume and inner diameter of the reactor can be adjusted appropriately depending on the production scale of the powder. The maximum diameter and rotation speed of the stirring blades can be adjusted depending on the volume and inner diameter of the reactor by adjusting the above d / D and n 3 ·d 5 It is preferable that the range satisfies / V. In one embodiment, the rotation speed of the stirring blade is preferably 50 to 500 rpm, more preferably 60 to 450 rpm, and even more preferably 80 to 400 rpm.

[0060] d / D is 0.90 or more, preferably 0.91 or more, and more preferably 0.92 or more. When d / D is equal to or more than the upper limit, the polymerization rate is likely to be good, and the bulk density of the polymer slurry is less likely to decrease, so that the batch yield tends to be good. From the viewpoint of polymerization apparatus safety, d / D is preferably 0.98 or less, more preferably 0.97 or less, and even 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 even more preferably 0.92 to 0.96.

[0061] n 3 ·d 5 / V is an index of stirring power, and n 3 ·d 5 The larger the / V, the greater the stirring force. 3 ·d 5 / V is 1.00m 2 / s 3 and above 1.50m 2 / s 3 It may be more than 2.00m 2 / s 3 It may be more than n 3 ·d 5 When / V is equal to or greater than the lower limit, the polymerization rate is likely to be good, and the bulk density of the polymer slurry is unlikely to decrease, so that the batch yield is likely to be good. 3 ·d 5 / V is 15.00m 2 / s 3 Less than 12.00m is preferred 2 / s 3 Less than 10.00m is preferred 2 / s 3 The following is more preferable. From this viewpoint, n 3 ·d 5 / V is 1.00~15.00m 2 / s 3 is preferable, 1.50 to 12.00 m 2 / s 3 May be 2.00 to 10.00 m 2 / s 3 may be. d / D and n 3 ·d 5 By adjusting / V within the above range, the stirring force becomes appropriately large, and it becomes easy to suitably obtain the present copolymer having an angle of repose of 37 to 43 degrees, a collapse angle of 24 to 31 degrees, and a difference angle of 10 to 16 degrees.

[0062] <Molded body> In one embodiment, a molded body is provided from the powder of the present disclosure. The molded body is obtained by molding the powder of the present disclosure. Examples of the molded body include injection molded bodies, extrusion molded bodies, blow molded bodies, transfer molded bodies, press molded bodies, rotational molded bodies, powder compacts, and coating films obtained by electrostatic coating.

[0063] In one embodiment, the molded body may be in the form of pellets. Examples of methods for molding pellets include using the powder of the present disclosure as a molding material, extruding the molding material while melting it using a single-screw extruder, a twin-screw extruder, or a tandem extruder, and cutting it to a predetermined length to mold it into pellets. The extrusion temperature from the extruder can be adjusted appropriately depending on the melt viscosity of the present copolymer and the production method, and is preferably from the melting point of the present copolymer + 20°C to the melting point of the present copolymer + 140°C. The extruded molding material can be cut by a method such as a strand cut method, a hot cut method, an underwater cut method, or a sheet cut method. The resulting pellets may be heated to remove volatile components (degassing treatment). The resulting pellets may be treated by contacting them with hot water at 30 to 200°C, steam at 100 to 200°C, or hot air at 40 to 200°C.

[0064] In the molded product (pellet, etc.), the copolymer has a total number of functional groups (hereinafter also referred to as "specific functional groups") selected from the group consisting of -CF=CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2, and -CH2OH (hereinafter also referred to as "number of specific functional groups") that is less than or equal to 10 main chain carbon atoms of the copolymer. 6 It is preferable that the number of specific functional groups is 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 upper limit, decomposition from the terminal functional groups is suppressed, and the heat resistance of the molded product is likely to be improved. In addition, since the corrosiveness of metals caused by decomposition products from the terminal functional groups can be suppressed, the amount of metal mixed into the molded product by melt molding tends to be suppressed. It is preferable that the number of specific functional groups is small, but it is also preferable that the number of specific functional groups is not large, and it is preferable that the number of specific functional groups is not large, and it is also ... possible to suppress the amount of metal mixed into the molded product by melt molding. 6 There may be one or more, two or more, or three or more per piece.

[0065] The specific functional group is a functional group present at the main chain terminal or side chain terminal of the copolymer, and a functional group present in the main chain or side chain. The specific functional group is introduced into the copolymer, for example, by a chain transfer agent or polymerization initiator used in the production of the copolymer. More specifically, for example, when an alcohol is used as a chain transfer agent or when a peroxide having a -CHOH structure is used as a polymerization initiator, -CHOH is introduced into the main chain terminal of the copolymer. The specific functional group can also be introduced into the side chain terminal of the copolymer by polymerizing a monomer having a functional group.

[0066] The type and number of functional groups in the copolymer can be identified and measured 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 prepare a film with a thickness of 0.25 to 0.30 mm. This film is analyzed by Fourier transform infrared spectroscopy (FT-IR) to obtain an infrared absorption spectrum of the copolymer. Separately, an infrared absorption spectrum (base spectrum) is obtained that is completely fluorinated and does not contain any specific functional groups, 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 functional groups in the copolymer with 10 main chain carbon atoms is determined according to the following formula (A): 6 Calculate the number of functional groups per molecule, N.

[0067] N=I×K / t (A) I: Absorbance K: Correction coefficient t: film thickness (mm)

[0068] The absorption frequency, molar absorption coefficient, and correction factor for specific functional groups are shown in Table 1. The molar absorption coefficient for a specific functional group is determined from FT-IR (Fourier transform infrared spectroscopy) measurement data of a low molecular weight model compound.

[0069] [Table 1]

[0070] In this copolymer, the absorption frequencies of -CH2CF2H, -CH2COF, -CH2COOH, -CH2COOCH3, and -CH2CONH2 are calculated by multiplying the absorption frequencies of -CF2H, -COF, -COOH (free and bonded), -COOCH3, and -CONH2 shown in the table by several tens of Kaiser (cm -1 For example, the number of -COFs is lower than the absorption frequency of 1883 cm due to -CF2COF. -1 The number of functional groups determined from the absorption peak of -CH2COF and the absorption frequency of 1840 cm -1The number of functional groups is the sum of the number of functional groups determined from the absorption peaks of the compounds.

[0071] In one embodiment, the copolymer may be fluorinated to convert specific functional groups to -CF3 terminal groups, thereby reducing the number of functional groups. The number of functional groups in the copolymer can be adjusted by changing the conditions of the fluorination treatment (treatment time, etc.). The fluorination treatment is carried out by contacting the unfluorinated copolymer with a fluorine-containing compound. The fluorine-containing compound may be a fluorine radical source that generates fluorine radicals under fluorination treatment conditions. Examples of the fluorine radical source include F2 gas, N2F2, and halogen fluorides (e.g., IF5 and ClF3).

[0072] The concentration of the fluorine radical source such as F2 gas may be 100% by volume. From the viewpoint of safety, it is preferable to use a mixed gas obtained by diluting the F2 gas with an inert gas so that the concentration is 5 to 50% by volume (preferably 15 to 30% by volume). Examples of the inert gas include nitrogen gas, helium gas, and argon gas, and from the viewpoint of economy, nitrogen gas is preferred.

[0073] The temperature during the fluorination treatment is preferably equal to or lower than the melting point of the present copolymer, more preferably 20 to 240° C., and even more preferably 100 to 235° C. The fluorination treatment may be carried out by contacting the present copolymer in a molten state with a fluorine-containing compound.

[0074] The treatment time for the fluorination treatment can be adjusted appropriately depending on the number of functional groups in the copolymer before the fluorination treatment, the desired number of functional groups, and the fluorination treatment method, and is, for example, 0.5 to 30 hours, preferably 1 to 24 hours.

[0075] Specific methods for the fluorination treatment include, for example, placing a shelf with pellets in an oven, filling the oven with F gas or a mixed gas, and heating for a certain period of time. Another example is a method in which F gas or a mixed gas is passed through a flow column filled with pellets while heating the column.

[0076] In one embodiment, the molded article may be a powder of the present disclosure molded into a shape having a specific function, or the molded article may be a pellet molded into a specific shape using the pellet as a molding material. Examples of molded articles include nuts, bolts, joints, films, bottles, gaskets, wire coating materials, tubes, hoses, pipes, valves, sheets, seals, packing, tanks, rollers, containers, cocks, connectors, filter housings, filter cages, flow meters, valves, pumps, wafer carriers, and wafer boxes.

[0077] The molded articles can be used, for example, in the following applications: fluid transfer components for food manufacturing equipment, such as food packaging films, lining materials for fluid transfer lines used in food manufacturing processes, packings, sealing materials, and sheets; chemical liquid transfer components, such as chemical stoppers, packaging films, lining materials for fluid transfer lines used in chemical manufacturing processes, packings, sealing materials, and sheets; 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 automobile fuel systems and peripheral devices, and hoses and sealing materials used in automobile automatic transmissions; carburetor flange gaskets, shaft seals, valve stem seals, sealing materials, and hoses used in automobile engines and peripheral devices, as well as other automobile components, such as automobile brake hoses, air conditioner hoses, radiator hoses, and wire coating materials; semiconductors, such as O-rings, tubes, packings, valve core materials, hoses, sealing materials, rolls, gaskets, diaphragms, and fittings for semiconductor manufacturing equipment. chemical liquid transfer components for equipment; paint and ink components such as paint rolls, hoses, tubes, and ink containers for paint equipment; food and beverage transfer components such as tubes, hoses, belts, packing, and joints, such as food and beverage tubes and 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; interior materials used in the construction field, and glass coating materials, such as non-flammable fire-resistant safety glass; and lining materials, such as laminated steel sheets, used in home appliances, etc.

[0078] In one embodiment, the molded article can be suitably used as a piping member (e.g., piping, joints, gaskets, and packing), a tube, or a film for transporting a fluid. The molded article can be suitably used, for example, as a chemical solution transporting member for a semiconductor device.

[0079] In one embodiment, the molded article can 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 a molded article using the powder of the present disclosure. A coated electric wire having a coating layer made of a molded article using the powder of the present disclosure has excellent electrical properties because the core wire is resistant to corrosion and there is little change in outer diameter, and can be suitably used as a high-frequency transmission cable, a flat cable, a heat-resistant cable, etc.

[0080] In one embodiment, the molded article can 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, an annular shape. Furthermore, 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 the center. The compressed member can be suitably used as a piping member for transporting a fluid. 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 a state in contact with the nonaqueous electrolyte in the nonaqueous electrolyte battery. The compressible member can also be suitably used as a sealing member such as a sealing gasket and sealing packing, and 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 for electrical insulation. The compressible member may be a member used for both sealing and insulating purposes.

[0081] The powder of the present disclosure can reduce the load on piping during transportation, and therefore is less likely to cause deterioration of resin linings in piping, for example, in semiconductor manufacturing processes. Therefore, in one embodiment, the molded article can be suitably used for semiconductor components (e.g., tubes, valves, unions, solenoid valves, sensors, etc.). In particular, molded articles made from fluorinated powder or pellets have stabilized unstable terminal functional groups, which suppresses the generation of impurities such as fluoride ions, making them particularly suitable as semiconductor components. [Example]

[0082] Next, embodiments of the present disclosure will be described in detail using examples, but the embodiments of the present disclosure are not limited to these examples. In the following examples, Examples 1 to 6 are examples, and Examples 7 to 14 are comparative examples.

[0083] The abbreviations for each compound are as follows: TFE: Tetrafluoroethylene PPVE: Perfluoro(propyl vinyl ether) HFP: hexafluoropropylene tBuOH: tert-butyl alcohol AE-3000 (product name, manufactured by AGC; 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether; CF3CH2OCF2CF2H)

[0084] The various measurement methods are as follows.

[0085] (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 an F-nuclear magnetic resonance spectrometer (AVANCE-III-HD400 manufactured by Bruker Biospin), and the calculated molar ratio was converted into a mass ratio from the chemical structural formula of each unit.

[0086] (MFR (Melt Flow Rate)) For the powder obtained in each example, a melt flow tester (Shimadzu Corporation, "CFT-500EX") was used to measure the mass (g) of molding material flowing out of an orifice with a diameter of 2.095 mm and a length of 8 mm in 10 minutes under conditions of a temperature of 372°C and a load of 5 kg in accordance with ASTM D1238, and this was taken as MFR (g / 10 min).

[0087] (Angle of repose and collapse angle) The powder obtained in each example was sieved through a 2360 μm mesh sieve and then measured for angle of repose and angle of collapse using the injection method at 25°C and 50% RH using a Multitester MT-02 (Seishin Enterprise Co., Ltd.). Specifically, the powder was injected vertically using a funnel toward the center of an 80 mm diameter circular horizontal plate attached to the Multitester MT-02, forming a cone-shaped powder on the plate. The powder was injected until the cone maintained its shape, and the angle of repose was measured using a protractor. Next, a 109 g weight placed on the same base as the horizontal plate was dropped three times from a height of 160 mm. After some of the powder collapsed and fell off due to the impact, the angle of collapse was measured using a protractor.

[0088] (difference angle) The difference angle was calculated using the following formula (1). Difference angle = angle of repose - angle of collapse (1)

[0089] [Example 1] A 2.5 L polymerization vessel (vessel diameter 125 mm, manufactured by Taiatsu Glass Industries Co., Ltd.) equipped with a stirrer (double helical ribbon blade, blade diameter 116 mm) was degassed, and then 1164 g of AE-3000, 668 g of water, 67 g of tBuOH, 156 g of PPVE, and 36.6 g of methanol (chain transfer agent) were charged into the polymerization vessel. The mixed solvent of AE-3000, water, and tBuOH separated into two phases at 25°C. The temperature inside the polymerization vessel was then raised to 50°C (polymerization temperature), and 268 g of TFE was further charged, and the pressure inside the polymerization vessel was increased to 1.34 MPa (gauge pressure). The stirring blade rotation speed was set to 300 rpm, and 3.2 mL of a 0.06 mass% AE-3000 solution of heptafluorobutyroyl peroxide was charged as a polymerization initiator solution to initiate polymerization. Subsequently, the polymerization initiator solution was continuously added. Furthermore, TFE was continuously charged so that the pressure during polymerization remained the same as the pressure at the start of polymerization. 320 minutes after the start of polymerization, 76.6 mL of the polymerization initiator solution was added, and 250 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 vessel reached 1 atm.

[0090] The resulting copolymer slurry was filtered to separate the polymerization medium, and then dried at 150° C. for 15 hours to obtain a powder of copolymer 1. The results of melt NMR analysis and infrared absorption spectroscopy showed that the composition of Copolymer 1 was TFE units / PPVE units=96.5 / 3.5 (mass%), and the MFR was 14 g / 10 min.

[0091] [Example 2] Polymerization was carried out in the same manner as in Example 1, except that the amounts of PPVE, TFE, methanol, and initial polymerization initiator solution initially charged into the polymerization vessel were changed to 101 g, 278 g, 38.9 g, and 2.8 mL, respectively, and the amount of polymerization initiator solution continuously charged was changed to 68.9 mL. The polymerization time was 277 minutes.

[0092] The resulting copolymer slurry was filtered to separate the polymerization medium, and then dried at 150° C. for 15 hours to obtain a powder of copolymer 2. The results of melt NMR analysis and infrared absorption spectroscopy showed that the composition of Copolymer 2 was TFE unit / PPVE unit=97.8 / 2.2 (mass%), and the MFR was 12 g / 10 min.

[0093] [Example 3] Polymerization was carried out in the same manner as in Example 1, except that the amounts of AE-3000, water, PPVE, TFE, methanol, and initial polymerization initiator solution charged into the polymerization vessel were changed to 1046 g, 643 g, 274 g, 248 g, 25.8 g, 2.2 mL, and 91.9 mL, respectively, and the amount of polymerization initiator solution continuously charged was changed to 91.9 mL. The polymerization time was 468 minutes.

[0094] The resulting copolymer slurry was filtered to separate the polymerization medium, and then dried at 150° C. for 15 hours to obtain a powder of copolymer 3. The results of melt NMR analysis and infrared absorption spectroscopy showed that the composition of Copolymer 3 was TFE units / PPVE units=93.3 / 6.7 (mass%), and the MFR was 15 g / 10 min.

[0095] [Example 4] Polymerization was carried out 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 159 g and 13.6 g, respectively. The polymerization time was 305 minutes.

[0096] The resulting copolymer slurry was filtered to separate the polymerization medium, and then dried at 150° C. for 15 hours to obtain a powder of copolymer 4. The results of melt NMR analysis and infrared absorption spectroscopy showed that the composition of Copolymer 4 was TFE unit / PPVE unit=96.4 / 3.6 (mass%), and the MFR was 2 g / 10 min.

[0097] [Example 5] Polymerization was carried out 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 173 g and 44.9 g, respectively. The polymerization time was 375 minutes.

[0098] The resulting copolymer slurry was filtered to separate the polymerization medium, and then dried at 150° C. for 15 hours to obtain a powder of copolymer 5. The results of melt NMR analysis and infrared absorption spectroscopy showed that the composition of Copolymer 5 was TFE unit / PPVE unit=96.1 / 3.9 (mass %), and the MFR was 36 g / 10 min.

[0099] [Example 6] A 2.5 L polymerization vessel (vessel diameter 125 mm, manufactured by Taiatsu Glass Industries Co., Ltd.) equipped with a stirrer (double helical ribbon blade, blade diameter 116 mm) was degassed, and 1381 g of AE-3000, 172 g of water, 50 g of tBuOH, 137 g of PPVE, 26.2 g of methanol, and 4.7 mL of a 0.06 wt% AE-3000 solution of heptafluorobutyroyl peroxide as a polymerization initiator solution were charged into the reaction vessel. The reaction vessel was cooled in an ice bath while the gas phase was degassed under reduced pressure. Note that the mixed solvent of AE-3000, water, and tBuOH separated into two phases at 25 °C. While stirring at a rotation speed of 300 rpm, 164 g of HFP and 295 g of TFE were pressurized into the reaction vessel, and the liquid phase temperature was raised to 50 °C to initiate solution polymerization. The pressure inside the reactor was 1.38 MPa, which was the initial pressure. Thereafter, the polymerization initiator solution was continuously added. Furthermore, TFE was continuously charged so that the pressure during polymerization was maintained at the same pressure as at the start of polymerization. After 402 minutes had elapsed since the start of polymerization, 91.9 mL of the polymerization initiator solution was added, and 250 g of TFE had been 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.

[0100] The resulting copolymer slurry was filtered to separate the polymerization medium, and then dried at 150° C. for 15 hours to obtain a powder of copolymer 6. The results of melt NMR analysis and infrared absorption spectroscopy showed that the composition of Copolymer 6 was TFE unit / HFP unit / PPVE unit=94.4 / 1.2 / 4.4 (mass%), and the MFR was 13 g / 10 min.

[0101] [Example 7] Polymerization was carried out in the same manner as in Example 1, except that a polymerization tank (tank diameter 125 mm) with an internal volume of 2.5 L and equipped with a stirrer (anchor blade, blade diameter 100 mm) and a baffle plate (width 10 mm) was used and the rotation speed of the stirring blade was set to 380 rpm. The polymerization time was 303 minutes.

[0102] The resulting copolymer slurry was filtered to separate the polymerization medium, and then dried at 150° C. for 15 hours to obtain a powder of copolymer 7. The results of melt NMR analysis and infrared absorption spectroscopy showed that the composition of Copolymer 7 was TFE unit / PPVE unit=96.5 / 3.5 (mol %), and the MFR was 14 g / 10 min.

[0103] [Example 8] Polymerization was carried out in the same manner as in Example 1, except that a polymerization tank (tank diameter 125 mm) with an internal volume of 2.5 L and equipped with a stirrer (three swept-back impellers, impeller diameter 100 mm) and a baffle plate (width 10 mm) was used and the rotation speed of the stirring impeller was set to 380 rpm. The polymerization time was 344 minutes.

[0104] The resulting copolymer slurry was filtered to separate the polymerization medium, and then dried at 150° C. for 15 hours to obtain a powder of copolymer 8. The results of melt NMR analysis and infrared absorption spectroscopy showed that the composition of Copolymer 8 was TFE unit / PPVE unit=96.5 / 3.5 (mol %), and the MFR was 14 g / 10 min.

[0105] [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 367 minutes.

[0106] The resulting copolymer slurry was filtered to separate the polymerization medium, and then dried at 150° C. for 15 hours to obtain a powder of copolymer 9. The results of melt NMR analysis and infrared absorption spectroscopy showed that the composition of Copolymer 9 was TFE units / PPVE units=96.5 / 3.5 (mol %), and the MFR was 14 g / 10 min.

[0107] [Example 10] Polymerization was carried out in the same manner as in Example 1, except that the amount of tBuOH added was 0 g. The polymerization time was 335 minutes.

[0108] The resulting copolymer slurry was filtered to separate the polymerization medium, and then dried at 150° C. for 15 hours to obtain a powder of copolymer 10. The results of melt NMR analysis and infrared absorption spectroscopy showed that the composition of Copolymer 10 was TFE unit / PPVE unit=96.5 / 3.5 (mol %), and the MFR was 14 g / 10 min.

[0109] [Example 11] Polymerization was carried out in the same manner as in Example 6, except that a polymerization tank (tank diameter 125 mm) with an internal volume of 2.5 L and equipped with a stirrer (anchor blade, blade diameter 100 mm) and a baffle plate (width 10 mm) was used and the rotation speed of the stirring blade was set to 380 rpm. The polymerization time was 418 minutes.

[0110] The resulting copolymer slurry was filtered to separate the polymerization medium, and then dried at 150° C. for 15 hours to obtain a powder of copolymer 11. The results of melt NMR analysis and infrared absorption spectroscopy showed that the composition of copolymer 11 was TFE unit / HFP unit / PPVE unit=94.4 / 1.2 / 4.4 (mass%), and the MFR was 13 g / 10 min.

[0111] [Example 12] Polymerization was carried out in the same manner as in Example 6, except that a polymerization tank (tank diameter 125 mm) with an internal volume of 2.5 L and equipped with a stirrer (three swept-back impellers, impeller diameter 100 mm) and a baffle plate (width 10 mm) was used and the rotation speed of the stirring impeller was set to 380 rpm. The polymerization time was 430 minutes.

[0112] The resulting copolymer slurry was filtered to separate the polymerization medium, and then dried at 150° C. for 15 hours to obtain a powder of copolymer 12. The results of melt NMR analysis and infrared absorption spectroscopy showed that the composition of Copolymer 12 was TFE unit / HFP unit / PPVE unit=94.4 / 1.2 / 4.4 (mass%), and the MFR was 13 g / 10 min.

[0113] [Example 13] Polymerization was carried out in the same manner as in Example 6, except that the rotation speed of the stirring blade was set to 200 rpm. The polymerization time was 422 minutes.

[0114] The resulting copolymer slurry was filtered to separate the polymerization medium, and then dried at 150° C. for 15 hours to obtain a powder of copolymer 13. The results of melt NMR analysis and infrared absorption spectroscopy showed that the composition of Copolymer 13 was TFE unit / HFP unit / PPVE unit=94.4 / 1.2 / 4.4 (mass%), and the MFR was 13 g / 10 min.

[0115] [Example 14] Polymerization was carried out in the same manner as in Example 6, except that the amount of tBuOH was 0 g. The polymerization time was 410 minutes.

[0116] The resulting copolymer slurry was filtered to separate the polymerization medium, and then dried at 150°C for 15 hours to obtain a powder of copolymer 14. Melt NMR analysis and infrared absorption spectroscopy revealed that the composition of copolymer 14 was TFE unit / HFP unit / PPVE unit = 94.4 / 1.2 / 4.4 (mass%). The MFR was 13 g / 10 min.

[0117] (Flow initiation velocity and accumulation limit velocity) The resulting copolymer powder was used to evaluate the powder flow initiation velocity and critical flow velocity within the tube using the following method. 50 g of copolymer powder was sealed in a polycarbonate tube with an inner diameter of 20 mm and a length of 500 mm, placed horizontally on a mix rotor, and rotated at 60 rpm for 5 minutes to deposit the copolymer powder within the tube. The tube was placed horizontally with both ends open, and air was introduced into one side, gradually increasing the air flow rate to fluidize the copolymer powder. The flow state was visually confirmed, and the air flow velocity, defined below, was recorded for each. Measurements were performed in triplicate for each copolymer powder, and the average was taken as the measured value.

[0118] Air flow rate (m / min): Flow rate (m 3 / min) / cross-sectional area of ​​polycarbonate pipe (m 2 ) Flow initiation velocity (m / min): the air velocity at which part of the copolymer powder begins to flow Deposition critical flow rate (m / min): The air flow rate at which all of the copolymer powder flows as suspended powder and no powder is observed deposited at the bottom of the pipe.

[0119] Tables 2 and 3 show the polymerization conditions, copolymer composition, MFR, angle of repose, angle of collapse, angle of difference, flow initiation velocity, and critical velocity for deposition 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 the maximum diameter of the impeller d [m], the inner diameter of the reaction vessel D [m], and the rotation speed of the impeller per second n [s -1 ], the volume of the reaction vessel is V [m 3 ] are the calculated values.

[0120] [Table 2]

[0121] [Table 3]

[0122] From the above results, it can be seen that for the powders of Examples 1 to 7, which have an angle of repose of 37 degrees or more and 43 degrees or less, a collapse angle of 24 degrees or more and 31 degrees or less, and a difference angle of 10 degrees or more and 16 degrees or less, the flow initiation flow velocity is 80 or less, and the deposition limit flow velocity is 340 or less. Therefore, the powder can be transported with low pressure, and the load on the inside of the piping is reduced. This is thought to suppress deterioration such as peeling of the resin lining, and to achieve both high powder cleanliness and a long manufacturing equipment life.

Claims

1. A powder containing as a main component a copolymer containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether), the powder having an angle of repose of 37 to 43 degrees, a collapse angle of 24 to 31 degrees, and a difference angle of 10 to 16 degrees.

2. 2. The powder according to claim 1, wherein the content of the units based on tetrafluoroethylene is 92.0 to 98.0 mass% based on all monomer units of the copolymer.

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

4. 2. The powder of claim 1, having a melt flow rate of 1.0 to 40.0 g / 10 min, measured at 372°C according to ASTM D1238.

5. 2. The powder of claim 1, wherein the perfluoro(alkyl vinyl ether)-based units comprise perfluoro(propyl vinyl ether)-based units.

6. A compact of the powder according to any one of claims 1 to 5.

7. The method comprises polymerizing tetrafluoroethylene and perfluoro(alkyl vinyl ether) in a polymerization medium in the presence of a radical initiator in a reaction vessel equipped with a helical ribbon impeller as an agitator, to produce a copolymer powder containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether); the radical initiator comprises an organic peroxide; the polymerization medium comprises water, a nonionic fluorine-containing organic compound, and an alcohol, and separates into two phases at 25°C; 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 1.00m ２ / s ３ This completes the method for producing the powder.

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