Solid material, molded body, and method for producing solid material

Abstract

The present invention addresses the problem of providing: a solid material with which it is possible to form a molded body that has excellent ozone resistance and in which blisters due to ozone are unlikely to occur; a molded body; and a method for producing a solid material.　A solid material according to the present invention is in the form of a powder or pellets and contains a copolymer that comprises a unit A which is based on tetrafluoroethylene and a unit B which is based on a monomer that is selected from the group consisting of monomers represented by formula (1) (CF2=CF-O-(CF2)n-CF3) and monomers represented by formula (2) (CF2=CF-CF2-O-(CF2)n-CF3). The total number of functional groups of -CF=CF2, -CF2H, -COF, -COOH ,-COOCH3, -CONH2, and -CH2OH is less than 150 per 106 carbon atoms in the main chain of the copolymer, and the solid material does not substantially contain a compound represented by formula (3) (CF3-(CF2)n-1-COOH).

Description

Solid matter, molded body, method for manufacturing solid matter

[0001] This invention relates to solid matter, molded articles, and methods for producing solid matter.

[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. For example, Patent Document 1 describes a copolymer containing tetrafluoroethylene units and perfluoro(propyl vinyl ether) units, with a main chain of 10 carbon atoms. ６ A copolymer having 50 or fewer molecules per unit is disclosed.

[0003] Japanese Patent Publication No. 2022-132127

[0004] Recently, when PFA molded bodies are used as piping materials for semiconductor manufacturing equipment, there is a growing demand for even greater ozone resistance in these molded bodies. When the present inventors evaluated a molded body formed using the copolymer manufactured according to Patent Document 1, they found that the ozone resistance did not meet the higher requirements demanded today, and that further improvements were necessary.

[0005] This invention has been made in view of the above problems and aims to provide a solid that can form a molded article that is less prone to ozone-induced blistering and has excellent ozone resistance. Furthermore, this invention also aims to provide a method for manufacturing both the molded article and the solid.

[0006] As a result of diligent study on the above problem, the present inventors have provided a powdered or pelletized solid containing a copolymer comprising a unit A based on tetrafluoroethylene and a unit B based on a monomer selected from the group consisting of a monomer represented by a specific formula (1) and a monomer represented by formula (2), wherein the copolymer has -CF=CF ２ , -CF ２ H, -COF, -COOH, -COOCH ３ , -CONH ２ and -CH ２ The total number of OH functional groups in the copolymer is equal to the number of carbon atoms in the copolymer. ６By using a solid material that contains less than 150 per individual and substantially does not contain a compound represented by a specific formula (3), it has been found that a molded article excellent in ozone resistance can be formed, leading to the present invention.

[0007] That is, the inventors have found that the above problems can be solved by the following constitution. [1] A powdery or pellet状 solid material containing a copolymer containing a unit A based on tetrafluoroethylene and a unit B based on a monomer selected from the group consisting of a monomer represented by the following formula (1) and a monomer represented by the following formula (2), -CF = CF ２ , -CF ２ H, -COF, -COOH, -COOCH ３ , -CONH ２ And -CH ２ The total number of functional groups of OH is 10 carbon atoms in the main chain of the above copolymer ６A solid characterized in that it contains less than 150 units per unit and substantially does not contain the compound represented by formula (3) described later. [2] The solid according to [1], wherein the content of unit A is 95.0 to 99.5 mol% of the total units of the copolymer. [3] The solid according to [1], wherein the content of unit A is 97.0 to 99.5 mol% of the total units of the copolymer. [4] The solid according to any one of [1] to [3], wherein the content of unit B is 0.5 to 5.0 mol% of the total units of the copolymer. [5] The solid according to any one of [1] to [4], wherein the melt flow rate of the copolymer, measured under conditions of a temperature of 372°C and a load of 5 kg in accordance with ASTM D1238, is 1.0 to 50.0 g / 10 min. [6] A solid according to any one of [1] to [5], wherein the above unit B includes at least one selected from the group consisting of units based on perfluoro(propyl vinyl ether) and units based on perfluoro(propyl allyl ether). [7] A molded article characterized by being obtained by molding the solid according to any one of [1] to [6]. [8] A powdered solid containing a copolymer comprising a unit A based on tetrafluoroethylene and a unit B based on a monomer selected from the group consisting of a monomer represented by formula (1) described later and a monomer represented by formula (2) described later, is fluorinated, and the fluorinated powdered solid is heated at 100 to 250°C for 1 hour or more to obtain a copolymer containing the above unit A and the above unit B, wherein the total number of functional groups of the main chain of the copolymer is 10 ６ A method for producing a solid, characterized by obtaining a powdered or pelletized solid containing a copolymer having fewer than 150 units per unit. [9] The bulk density of the powdered solid subjected to the fluorination treatment is 0.10 to 0.70 g / cm³. ３ The method for producing a solid according to [8].

[10] The method for producing a solid according to [8] or [9], wherein the fluorinated powdered solid is heated under reduced pressure of 2.0 kPa or less.

[0008] According to the present invention, it is possible to provide a solid material that can form a molded article with excellent ozone resistance, which is less prone to ozone-induced blistering. Furthermore, according to the present invention, it is possible to provide a method for manufacturing both the molded article and the solid material.

[0009] In this specification, the meanings of terms are as follows: A numerical range indicated by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively.

[0010] "Unit" is a general term for atomic groups derived from one monomer molecule directly formed by the polymerization of monomers, and atomic groups obtained by chemically transforming a part of the above atomic group. In the following, depending on the case, units derived from individual monomers will be referred to by adding "unit" to the monomer name. "Unit A" is a unit based on tetrafluoroethylene contained in the copolymer. "Monomer B1" is the monomer represented by formula (1) described later, "Monomer B2" is the monomer represented by formula (2) described later, and "Monomer B" is a monomer selected from the group consisting of monomer B1 and monomer B2. "Unit B," "Unit B1," and "Unit B2" are units based on monomer B, monomer B1, and monomer B2 contained in the copolymer, respectively.

[0011] "Specific functional group" refers to -CF=CF ２ , -CF ２ H, -COF, -COOH, -COOCH ３ , -CONH ２ and -CH ２ This refers to the functional groups included in the group consisting of OH. Furthermore, "number of functional groups" refers to the total number of specific functional groups present in the copolymer, unless otherwise specified.

[0012] "Solid matter" refers to a composition that is solid at 25°C. "Powdered solid matter" refers to a material with an average particle size of 3000 μm or less and a bulk density of 0.10 to 0.80 g / cm³. ３ This refers to an object that is a pelletized solid. "Pelletized solid" means a particulate molded product manufactured by extruding and cutting a solid. Pressure as used herein refers to absolute pressure.

[0013] [First Embodiment: Solid Matter] The solid matter according to the first embodiment of the present invention (hereinafter also referred to as "the solid matter") is a powdered or pelletized solid matter containing a copolymer (hereinafter also referred to as "the copolymer") which contains unit A and unit B and has a specific functional group within a predetermined content range. Furthermore, the solid matter substantially does not contain a compound represented by a specific formula (3).

[0014] By using this solid material, it is possible to form molded articles with excellent ozone resistance that are less prone to ozone-induced blistering. The detailed reasons for this are not yet clear, but it is presumed to be due to the following reasons. As a result of diligent research, the inventors have found that a compound represented by a specific formula (3) (hereinafter also referred to as "compound (3)") can affect the ozone resistance of molded articles formed using PFA. When ozone, which has strong oxidizing power, comes into contact with compound (3) contained in the molded article, the carboxylic acid portion of compound (3) is decomposed by the ozone and CO2 is released. ２ CO is eliminated (decarboxylation reaction), and the CO produced ２ It is presumed that this causes foaming (blistering) to occur on the surface of the molded product. Furthermore, in compound (3), after the carboxylic acid moiety is decomposed, -CF ２ -It is presumed that the group reacts with ozone to produce hydrofluoric acid, and that this hydrofluoric acid also contributes to the generation of foam. Compound (3) is presumed to be produced during the manufacturing process of PFA, particularly when PFA is fluorinated. In contrast, by using a powdered or pelletized solid containing a copolymer containing units A and B, which substantially does not contain compound (3), the CO2 released when in contact with ozone is reduced. ２ Furthermore, it is presumed that the formation of hydrofluoric acid is suppressed, and a molded article with improved ozone resistance can be formed. In addition, it is presumed that by fluorinating a powdered solid with a bulk density within a specific range, and then performing a heat treatment at a predetermined temperature for a predetermined time after the fluorination treatment, a molded article that substantially does not contain compound (3) and similarly has improved ozone resistance can be formed. Furthermore, the total number of specific functional groups that the copolymer has is such that the main chain of the copolymer has 10 carbon atoms. ６It is presumed that the presence of fewer than 150 ozone molecules per unit suppresses the oxidative decomposition of specific functional groups by ozone. Thus, it is presumed that by satisfying each requirement, a molded product with excellent ozone resistance was obtained.

[0015] The content of the copolymer in the solid is preferably 70% to 100% by mass, more preferably 90% to less than 100% by mass, and even more preferably 99% to less than 100% by mass, based on the total mass of the solid. When the content of the copolymer is within the above range, it is easy to produce molded articles with excellent ozone resistance from the solid.

[0016] <This copolymer> This copolymer contains at least unit A and unit B.

[0017] The content of unit A is preferably 95.0 to 99.5 mol%, more preferably 97.0 to 99.5 mol%, and even more preferably 98.0 to 99.5 mol%, relative to the total units contained in the copolymer, in terms of superior heat resistance.

[0018] Unit B is a unit based on monomer B selected from the group consisting of monomer B1 represented by the following formula (1) and monomer B2 represented by the following formula (2). CF ２ =CF - O - (CF ２ ) ｎ -CF ３ (1) CF ２ = CF - CF ２ -O-(CF ２ ) ｎ -CF ３ (2) In formulas (1) and (2), n represents 1 to 9. In formulas (1) and (2), n 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.

[0019] Specific examples of monomer B1 include perfluoro(methyl vinyl ether) (PMVE), perfluoro(ethyl vinyl ether) (PEVE), and perfluoro(propyl vinyl ether) (PPVE), with PMVE or PPVE being preferred, and PPVE being more preferred. Specific examples of monomer B2 include perfluoro(methyl allyl ether), perfluoro(ethyl allyl ether), perfluoro(propyl allyl ether) (PFAE), and perfluoro(butyl allyl ether), with perfluoro(methyl allyl ether), perfluoro(ethyl allyl ether), or PFAE being preferred, and PFAE being more preferred.

[0020] Preferably, monomer B is a monomer B in which n is within the above preferred range, more preferably at least one of the monomers listed as specific examples of monomer B1 and monomer B2, even more preferably at least one selected from the group consisting of PMVE, PPVE, perfluoro(methyl allyl ether), perfluoro(ethyl allyl ether), and PFAE, and particularly preferably at least one selected from the group consisting of PPVE and PFAE.

[0021] The content of unit B is preferably 0.5 to 5.0 mol%, more preferably 1.0 to 3.0 mol%, and even more preferably 1.5 to 2.5 mol%, relative to the total units contained in the copolymer, in terms of superior moldability and mechanical properties. The copolymer may contain two or more types of unit B. If the copolymer contains two or more types of unit B, it means that the total content of the two or more types of unit B is within the above range.

[0022] In this copolymer, the total content of unit A and unit B is preferably 95.5 to 100.0 mol%, more preferably 97.5 to 100.0 mol%, even more preferably 99.0 to 100.0 mol%, and particularly preferably 99.5 to 100.0 mol%, relative to the total units contained in the copolymer, in order to prevent the resulting molded article from being easily deformed by compression or tension.

[0023] In addition to units A and B, this copolymer may also contain units based on TFE and other monomers copolymerizable with monomer B. Examples of other monomers include ethylene, vinylidene fluoride (VdF), hexafluoropropylene (HFP), and CX. １ X ２ = CX ３ (CF ２ ) ｎ X ４ (In the formula, X １ , X ２ and X ３ Each of these independently represents either a hydrogen atom or a fluorine atom, and X ４ ) represents a monomer, and CF ２ = CF - OCH ２ -Rf ２ (wherein, Rf ２ ) represents a perfluoroalkyl group having 1 to 5 carbon atoms. Examples include monomers represented by ). When the copolymer contains units based on other monomers, the content of units based on other monomers is preferably less than 4.5 mol%, more preferably less than 2.5 mol%, more preferably less than 1.0 mol%, and particularly preferably less than 0.5 mol%, relative to the total number of units contained in the copolymer.

[0024] This copolymer preferably contains only units A and B, and does not contain units based on the other monomers mentioned above, in order to have superior abrasion resistance during repeated use. In this case, the total content of units A and B is 100.0 mol% of the total units contained in the copolymer.

[0025] The respective content of unit A, unit B, and other monomer-based units in this copolymer is: １９ It can be measured by known methods such as F-NMR (nuclear magnetic resonance analysis).

[0026] (Number of functional groups) This copolymer has -CF=CF ２ , -CF ２ H, -COF, -COOH, -COOCH ３ , -CONH ２ and -CH ２The total number of specific functional groups in the group consisting of OH is equal to the carbon number of the copolymer (10 carbon atoms). ６ The number of functional groups per unit is less than 150. From the viewpoint of forming a molded article with superior ozone resistance, the number of functional groups is preferably less than 50, more preferably less than 20, and even more preferably 10 or less. The number of functional groups may be 0.

[0027] 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. The number of functional groups is the sum of the number of specific functional groups. Specific functional groups are introduced into the copolymer, for example, by a chain transfer agent or polymerization initiator used in the production of the copolymer. More specifically, this may occur when an alcohol is used as a chain transfer agent, or when -CH is used as a polymerization initiator. ２ When using a peroxide having an OH structure, -CH is added to the main chain end of the copolymer. ２ OH is introduced. Furthermore, by polymerizing monomers having functional groups, the functional groups are introduced to the side chain ends of the copolymer. Also, if the number of functional groups in a copolymer having specific functional groups exceeds a predetermined range, the copolymer is fluorinated to remove the specific functional groups -CF ３ The number of functional groups can be reduced by converting them to terminal groups. The number of functional groups in the copolymer can be adjusted by changing the conditions of the fluorination treatment described later (e.g., treatment time, etc.).

[0028] Infrared spectroscopy can be used to identify the types of functional groups and measure the number of functional groups in copolymers. Specifically, the number of functional groups is measured by the following method. First, the copolymer is molded by hot pressing at 330°C to produce a film with a thickness of 0.30 to 0.35 mm. This film is analyzed by Fourier transform infrared spectroscopy to obtain the infrared absorption spectrum of the copolymer. Separately, an infrared absorption spectrum (base spectrum) is obtained from a copolymer that is completely fluorinated and 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 copolymer is determined according to the following formula (A). ６ Calculate the number of functional groups N per individual.

[0029] N = I × K / t (A) I: Absorbance K: Correction factor t: Film thickness (mm)

[0030] 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.

[0031]

[0032] Furthermore, in copolymers, -CH ２ CF ２ H, -CH ２ COF, -CH ２ COOH, -CH ２ COOCH ３ and -CH ２ CONH ２ The absorption frequency is -CF shown in the table. ２ H, -COF, -COOH (free and bonded), -COOCH ３ , and also, -CONH ２ From each absorption frequency, several tens of kaiser (cm) －１ ) becomes lower. For example, the number of -COF is -CF ２ The absorption frequency due to COF is 1883 cm⁻¹. －１ The number of functional groups determined from the absorption peak, and -CH ２ The absorption frequency due to COF is 1840 cm⁻¹. －１ This is the sum of the number of functional groups determined from the absorption peaks.

[0033] (Melt Flow Rate) The MFR of this copolymer is preferably 1.0 to 50.0 g / 10 min, more preferably 3.0 to 45.0 g / 10 min, and even more preferably 5.0 to 40.0 g / 10 min, in order to form a molded article with a good balance of folding resistance and flexural strength. A specific example of a method to bring the MFR of this copolymer 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. The MFR of the copolymer is measured in accordance with ASTM D1238, under conditions of a temperature of 372°C and a load of 5 kg, and represents the mass (g) of the copolymer flowing out of an orifice with a diameter of 2 mm and a length of 8 mm in 10 minutes. Since this copolymer is the main component of this solid, and components other than this copolymer have almost no effect on the measurement of the MFR, the measured value of the MFR obtained by measuring this solid can be considered as the MFR of this copolymer.

[0034] (Melting Point) 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 low-speed tear strength of the molded article, the melting point of this copolymer is preferably 315.0°C or lower, more preferably 312.0°C or lower, and even more preferably 309.0°C or lower. A specific example of a method for adjusting the melting point of this copolymer to the above range is a method of adjusting the composition of this copolymer. The melting point of this copolymer is the temperature corresponding to the endothermic peak when the copolymer is heated using a scanning differential thermal analyzer in an air atmosphere at a rate of 10°C / min.

[0035] This solid may contain other components besides this copolymer. Specific examples of such other components include other resins, heat stabilizers, antioxidants, colorants, ultraviolet absorbers, fillers, crosslinking agents, crosslinking aids, and organic peroxides. When this solid contains other components, the content of the other components is preferably 0.0000001 to 5 parts by mass, more preferably 0.0000005 to 3 parts by mass, and even more preferably 0.000001 to 1 part by mass, per 100 parts by mass of this copolymer.

[0036] This solid material may be in powder or pellet form. The powdered solid material has an average particle size of 3000 μm or less and a bulk density of 0.10 to 0.80 g / cm³. ３ These are particles. In this specification, bulk density is measured in accordance with JIS K-5101-12-1:2004 and is also referred to as apparent density or loose bulk density. Specifically, a bulk density meter (e.g., manufactured by Kuramochi Scientific Instruments Co., Ltd.) is placed on an electronic balance (e.g., A&D "EK-1200A"), the sample to be measured is placed in the bulk density meter using a funnel, and then the sample that overflows from the opening surface is removed by leveling it flat along the opening surface of the bulk density meter, the weight of the sample is measured, and the bulk density is calculated by dividing the obtained weight by the internal volume of the meter. In this specification, the average particle diameter is measured using a laser diffraction / scattering particle size distribution analyzer (e.g., Horiba "LA-960V2"). Specifically, the average particle size is obtained by a wet measurement method in which the sample to be measured is dispersed in isopropanol solvent and the average particle size of the dispersed sample is measured. The powdered solid material may be primary particles or secondary particles formed by the aggregation of primary particles.

[0037] If the solid material is in pellet form, a granular molded body with a diameter or length of about 1 to 10 mm is preferred. The shape of the pelletized solid material is not limited, but it is usually spherical, ellipsoidal, or cylindrical.

[0038] This solid substance is substantially free of the compound represented by the following formula (3) (compound (3)). Formula (3) CF ３ - (CF ２ ) ｎ－１ -COOH In formula (3), n represents 1 to 9.

[0039] In this specification, "the solid is substantially free of the compound represented by formula (3)" means that the content of compound (3) in the solid (total content if two or more types of compound (3) are included; the same applies hereinafter) is less than 250 ppb by mass relative to the total mass of the solid. Preferably, the content of compound (3) in the solid is less than 150 ppb by mass, and more preferably less than 25 ppb by mass, relative to the total mass of the solid. The content of compound (3) may be 0 ppb by mass relative to the total mass of the solid.

[0040] The amount of compound (3) contained in the solid can be measured by extracting the component containing compound (3) from the solid using an alcohol solvent such as methanol, and then analyzing the extract using a liquid chromatography / mass spectrometry (LC-MS) instrument. Details of the method for measuring the amount of compound (3) are described in the examples below.

[0041] The content of compound (3) in the solid can be reduced, for example, by fluorinating a powdered solid with a bulk density within a specific range during the manufacturing of the solid, and then by heat-treating the fluorinated powdered solid. Details of the fluorination and heat treatment in the manufacturing of the solid will be described later.

[0042] In this solid, from the viewpoint of providing superior ozone resistance to molded articles formed from this solid, it is preferable that the content of a second copolymer containing unit A and units based on hexafluoropropylene, but not containing unit B, is less than 0.5% by mass, and more preferably 0% by mass, relative to the total content of the first copolymer and the second copolymer. Note that "not containing unit B" means that the content of unit B relative to the total units of the copolymer is 0.5 mol% or less.

[0043] <Method for Manufacturing Solid Matter> One example of a method for manufacturing this solid matter is to produce a copolymer, fluorine the powdered solid containing the produced copolymer, and then heat-treat the fluorinated powdered solid. The method for manufacturing this solid matter will be explained using the above method as an example.

[0044] The process for producing the copolymer includes using the above-mentioned monomers (TFE and monomer B) by known methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization, with solution polymerization being preferred. In addition to the above-mentioned monomers, polymerization initiators, polymerization media, and chain transfer agents can be used in the production of the copolymer.

[0045] The polymerization initiator is preferably a radical polymerization initiator with a half-life of 10 hours at a temperature of 0 to 100°C, and more preferably a radical polymerization initiator with a temperature 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. The amount of polymerization initiator used is preferably 0.01 to 0.9 parts by mass, and more preferably 0.05 to 0.5 parts by mass, per 100 parts by mass of monomer.

[0046] Examples of polymerization media include water, organic solvents, and mixed solvents of water and organic solvents. As organic solvents, fluorine-based solvents such as perfluorocarbons, hydrofluorocarbons, and hydrofluoroethers can be used. Specific examples of organic solvents include the polymerization media exemplified in International Publication No. 2013 / 015202. Polymerization media containing water are preferred, and ultrapure water is more preferred.

[0047] The polymerization medium may be used alone or in combination of two or more types. A mixed solvent of water and a fluorinated solvent is preferred as the polymerization medium, and a mixed solvent of water and perfluorocarbon is more preferred. From the viewpoint of suspendability and economic efficiency, the amount of fluorinated solvent used is preferably 10% by mass or more and less than 100% by mass of the total mass of the mixed solvent. The amount of polymerization medium used is preferably 3 times or more by mass ratio of the amount of monomer used, more preferably 5 times or more. Furthermore, 20 times or less is preferred, and 17 times or less is more preferred.

[0048] As chain transfer agents, 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 are used because they have a large chain transfer constant and require small amounts of addition; hydrocarbons such as n-pentane, n-hexane and cyclohexane; CF ２ H ２ Hydrofluorocarbons such as alcohols; 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, 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 alcohols are even more preferred, due to their higher chain transfer constant and high stability of the end groups of the copolymer. Among the alcohols, methanol or ethanol is preferred, and methanol is more preferred from the viewpoint of reactivity and availability. Two or more chain transfer agents may be used. The amount of chain transfer agent used is preferably 0.001 times or more by mass ratio of the amount of monomer used, more preferably 0.005 times or more. Also, 5 times or less is preferred, and 4 times or less is more preferred.

[0049] The polymerization temperature is preferably 15 to 60°C, more preferably 20 to 58°C, and even more preferably 25 to 55°C. If the polymerization temperature is 15°C or higher, excellent polymerizability can be obtained. If the polymerization temperature is 60°C or lower, the melting point of the copolymer can be improved. The polymerization pressure is preferably 0.5 to 3.0 MPa, and more preferably 0.9 to 2.5 MPa. The polymerization time is preferably 1 to 12 hours.

[0050] If polymerization yields an aqueous dispersion containing the copolymer, the copolymer can be recovered by coagulating, washing, and drying the copolymer contained in the aqueous dispersion. Alternatively, if polymerization yields the copolymer as a slurry, the copolymer can be recovered by removing the slurry from the reaction vessel, washing, and drying it.

[0051] Next, the powdered solid containing the obtained copolymer is subjected to a fluorination treatment. The powdered solid subjected to the fluorination treatment contains the above copolymer. The bulk density of the powdered solid subjected to the fluorination treatment is 0.10 to 0.80 g / cm³. ３ Therefore, in terms of superior end-processing efficiency, 0.10 to 0.75 g / cm³ ３ Preferably, 0.10 to 0.70 g / cm³ ３ More preferably, 0.15 to 0.70 g / cm³ ３ More preferably, 0.20 to 0.70 g / cm³ ３ That is particularly preferable.

[0052] If the copolymer obtained by polymerization is a powdery solid, the recovered copolymer may be fluorinated directly. If necessary, the copolymer obtained by polymerization may be pulverized to produce a powdery solid. The pulverization can be carried out using known pulverizers such as rotor mills, hammer mills, turbo mills, and jet mills.

[0053] Alternatively, a composition such as a pelletized solid or granulated material containing the copolymer obtained by polymerization may be manufactured, and the resulting composition may be pulverized to produce a powdered solid. The pelletized solid can be molded by conventionally known methods. Examples of methods for molding the pelletized solid include extruding the fluorinated copolymer 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 in melt extrusion is appropriately changed depending on the melt viscosity of the copolymer and the manufacturing method, but is preferably between +20°C and +140°C above the melting point of the copolymer. Conventional known methods such as strand cutting, hot cutting, underwater cutting, and sheet cutting can be used to cut the copolymer.

[0054] (Fluorination treatment) Next, as a fluorination treatment, a fluorinating agent is brought into contact with the powdered solid containing the copolymer obtained by polymerization. Through the fluorination treatment, the -COOH, -COOCH contained in the copolymer ３ ien-CH２ OH, -COF, -CF=CF ２ , -CONH ２ and -CF ２ H consisting of specific functional groups can be converted to -CF ３ . As a result, the number of specific functional groups can be reduced, and the number of functional groups of the copolymer can be adjusted within a predetermined range.

[0055] As the fluorinating agent, a fluorine radical source that generates fluorine radicals under fluorination treatment conditions can be mentioned. As the above fluorine radical source, F ２ gas, N ２ F ２ and halogen fluorides (for example, IF ５ and ClF ３ etc.) can be mentioned. The concentration of the fluorine radical source such as F ２ gas may be 100% by volume. From the viewpoint of safety, it is preferable to use a mixed gas obtained by diluting with an inert gas so that the concentration of F ２ gas is 5 to 50% by volume (more preferably 15 to 30% by volume). As the above inert gas, nitrogen gas, helium gas, and argon gas can be mentioned, and from the viewpoint of economy, nitrogen gas is preferable.

[0056] The treatment time of the fluorination treatment is appropriately changed depending on the number of functional groups of the copolymer before the fluorination treatment and the target number of functional groups, but for example, it is 0.5 to 30 hours, and 1 to 24 hours is preferable. The treatment temperature in the fluorination treatment is preferably below the melting point of the present copolymer, more preferably 20 to 240°C, and even more preferably 100 to 235°C.

[0057] As a specific method of the fluorination treatment, for example, a tray on which a powdery solid is placed is installed in an oven, and the inside of the oven is filled with F ２ gas or the above mixed gas and heated for a certain period of time can be mentioned. Also, while heating a flow-through column filled with a powdery solid, a method of flowing F ２ gas or the above mixed gas through the flow-through column for a certain period of time can also be mentioned. As a method of the fluorination treatment, from the viewpoint of reaction efficiency, a tray on which a powdery solid is placed is installed in an oven, and the inside of the oven is filled with F ２A preferred method is to fill the container with gas or a mixture of the above-mentioned gases and heat it for a certain period of time.

[0058] (Heat treatment) Next, the fluorinated powdered solid is heat-treated. It is preferable to heat the fluorinated powdered solid at 100 to 250°C for one hour or more, as this makes it easier to produce the solid.

[0059] Specific methods of heat treatment include, for example, placing a tray containing the fluorinated solid material in an oven and heating it. The heat treatment temperature is more preferably 100 to 250°C, even more preferably 150 to 200°C, and particularly preferably 160 to 190°C. The heat treatment time is more preferably 1 to 15 hours, even more preferably 3 to 10 hours, and particularly preferably 4 to 8 hours. The heat treatment may be carried out under atmospheric pressure, but it is preferable to carry it out under reduced pressure. When heat treatment is carried out under reduced pressure, the pressure is preferably 2.0 kPa or less, more preferably 1.5 kPa or less, and even more preferably 1.0 kPa or less, from the viewpoint of removal efficiency. When heat treatment is carried out under reduced pressure, the pressure is preferably 0 kPa or more, from the viewpoint of heating efficiency.

[0060] The solid obtained by the above-described fluorination treatment and heat treatment may be in powder form. Furthermore, the powdered or pelletized solid may be produced by subjecting the solid obtained by the above-described fluorination treatment and heat treatment to known treatments such as pelletization and pulverization.

[0061] [Second Embodiment: Method for Producing Solids] The method for producing solids according to the second embodiment of the present invention (hereinafter also referred to as "this production method") involves fluorinating a powdered solid containing a copolymer containing unit A and unit B, and heating the fluorinated powdered solid at 100 to 250°C for 1 hour or more to obtain a copolymer containing unit A and unit B, wherein the total number of specific functional groups of the copolymer main chain has 10 carbon atoms. ６This is a method for producing a solid material, which is a powder or pellet-like solid material containing a copolymer with fewer than 150 units per piece. This method produces a solid material that is a powder or pellet-like solid material containing a copolymer containing unit A and unit B, and which can form a molded body with excellent ozone resistance.

[0062] In this manufacturing method, the powdered solid and copolymer contained in the solid subjected to fluorination treatment are as described in the first embodiment, including preferred embodiments, except for the bulk density. The bulk density of the powdered solid subjected to fluorination treatment in this manufacturing method is 0.10 to 0.80 g / cm³. ３ Therefore, in terms of superior heating efficiency, 0.10 to 0.75 g / cm³ ３ Preferably, 0.10 to 0.70 g / cm³ ３ More preferably, 0.15 to 0.70 g / cm³ ３ More preferably, 0.20 to 0.70 g / cm³ ３ This is particularly preferable. Furthermore, the number of functional groups in the copolymer contained in the powdered solid subjected to fluorination treatment in this manufacturing method is usually 10 carbon atoms in the main chain of the copolymer. ６ There are over 150 of each.

[0063] The method for fluorinating the powdered solid in this manufacturing method is as already described in the fluorination treatment of the solid manufacturing method according to the first embodiment, including preferred embodiments.

[0064] In this manufacturing method, the fluorinated solid is heated at 100 to 250°C for at least one hour as a heat treatment. The heat treatment temperature is preferably 120 to 220°C, and more preferably 150 to 200°C. The heat treatment time is preferably 1 to 15 hours, and more preferably 3 to 12 hours. The heat treatment may be carried out under atmospheric pressure, but it is preferable to carry it out under reduced pressure. When heat treatment is carried out under reduced pressure, the pressure is preferably 2.0 kPa or less, more preferably 1.5 kPa or less, and even more preferably 1.0 kPa or less, from the viewpoint of removal efficiency. When heat treatment is carried out under reduced pressure, the pressure is preferably 0 kPa or more, from the viewpoint of heating efficiency. The specific method of heat treatment, including preferred embodiments, is as already described in the method for heating the fluorinated solid in the method for producing solid according to the first embodiment.

[0065] The solid obtained by the above-described fluorination treatment and heat treatment may be a powdered solid. Alternatively, a powdered or pelletized solid may be produced by subjecting the solid obtained by the above-described fluorination treatment and heat treatment (preferably a powdered solid) to known treatments such as pelletization and pulverization. The pelletization and pulverization treatments, including preferred embodiments, are as described in the method for producing the solid according to the first embodiment.

[0066] The solid produced by this manufacturing method preferably contains substantially no compound (3). That is, the content of compound (3) in the solid produced by this manufacturing method (total content if two or more types of compound (3) are included) is preferably less than 250 ppb by mass relative to the total mass of the solid. By producing the solid by this manufacturing method, it is easy to obtain a solid that contains substantially no compound (3). The content of compound (3) in the solid produced by this manufacturing method is more preferably less than 150 ppb by mass, and even more preferably less than 25 ppb by mass, relative to the total mass of the solid. The content of compound (3) may be 0 ppb by mass relative to the total mass of the solid. Other properties of the solid produced by this manufacturing method, including preferred embodiments, are as described for the solid according to the first embodiment.

[0067] [Molded Article] The molded article of the present invention is obtained by molding a solid material according to the first embodiment of the present invention, or a solid material manufactured by the manufacturing method according to the second embodiment of the present invention. Specific examples of the molded article of the present invention include injection molded articles obtained by injection molding of a solid material, extruded articles obtained by extrusion molding, blow molded articles obtained by blow molding, transfer molded articles obtained by transfer molding, press molded articles obtained by press molding, rotational molded articles obtained by rotational molding, and coatings obtained by electrostatic coating. The molded article of the present invention is preferably a press molded article obtained by press molding. Injection molded articles are also preferred because they can be obtained with a beautiful appearance without corroding the mold used for molding.

[0068] Specific examples of molded articles of the present invention 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, pumps, wafer carriers, and wafer boxes.

[0069] The solid material, the solid material produced by the manufacturing method according to the second embodiment, or the molded article of the present invention can be used for the following purposes. Fluid transfer components for food manufacturing equipment, such as food packaging films, lining materials, packings, seals, and sheets for fluid transfer lines used in food manufacturing processes; chemical stoppers, packaging films, lining materials, packings, seals, and sheets for fluid transfer lines used in pharmaceutical manufacturing processes; internal lining materials for chemical tanks and piping in chemical plants or semiconductor factories; O-rings, tubes, packings, valve cores, hoses, and seals used in automobile fuel systems and peripheral equipment, as well as fuel transfer components such as hoses and seals used in automobile automatic transmission systems; carburetor flange gaskets, shaft seals, valve stem seals, seals, and hoses used in automobile engines and peripheral equipment, as well as other automobile components such as automobile brake hoses, air conditioning hoses, radiator hoses, and wire insulation materials; semiconductor components 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 body 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 for food and beverages, hoses, belts, gaskets, and fittings, as well as 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 building sector, and coating materials for glass such as non-combustible fire-resistant safety glass; lining materials such as laminated steel sheets used in the home appliance sector, etc.

[0070] In particular, the molded articles of the present invention can be suitably used as piping components (e.g., pipes, fittings, gaskets, and packings) or tubes for transferring fluids in semiconductor manufacturing equipment. Furthermore, the molded articles of the present invention can be suitably used as wire coating materials. A specific example of use is a coated wire comprising a core wire and a coating layer made of the molded articles of the present invention provided around the core wire. A coated wire having a coating layer made of the molded articles of the present invention has excellent electrical properties because the core wire is resistant to corrosion and the outer diameter hardly changes, and is suitably used as a high-frequency transmission cable, flat cable, heat-resistant cable, etc. Such a coated wire can be manufactured, for example, by melt-extruding a copolymer or this composition onto a core wire to form the coating layer.

[0071] Furthermore, the molded body of the present invention can also be suitably used as a compressible member. A compressible member is a member used in a compressed and deformed state, and the size and shape of the compressible member are appropriately set according to the application. The shape of the compressible member may be, for example, annular. Also, the compressible member may have a circular, oval, or rounded-corner square shape in plan view, and may have a through hole in its center. The compressible member can be used as a piping member for transferring fluids. Furthermore, the compressible member can be used as a member for constituting a non-aqueous electrolyte battery, and is particularly suitable as a member 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 be a member used for both sealing and insulating purposes.

[0072] The present invention will be described in detail below with reference to examples. Examples 1, 2, and 5 are examples, and examples 3, 4, 6, and 7 are comparative examples. However, the present invention is not limited to these examples. Various measurement and evaluation methods are as follows.

[0073] [Measurement] <Composition of copolymer> The content (mol%) of unit A and unit B in each copolymer is: １９ The molar ratio was calculated by converting the values ​​obtained from F-NMR analysis.

[0074] <Number of Functional Groups N> Using the solids obtained in each example as raw materials, films with a thickness of 0.30 to 0.35 mm were prepared by hot pressing at 330°C. These films were scanned 40 times using a Fourier transform infrared spectrometer (FT-IR, "Spectrum One," PerkinElmer) and analyzed to obtain infrared absorption spectra. Next, the solids obtained in each example were subjected to the fluorination treatment described below for a long period of time to prepare separate base pellets that were completely fluorinated and free of specific functional groups, and base films were obtained in the same manner as above. Next, the difference spectrum between the infrared absorption spectrum of the film obtained by molding the solids in each example and the base spectrum of the base film was obtained. From the absorption peaks of the specific functional groups appearing in this difference spectrum, the number of carbon atoms in the main chain of the copolymer contained in each solid was determined according to formula (A) above. ６ The total number of specific functional groups per individual (number of functional groups N) was calculated.

[0075] <Content of Compound (3)> The solids obtained in each example were freeze-milled using a freeze mill "Freezer Mill 6775" (manufactured by SPEX) under the following conditions. Before freeze-milling, 10% by mass of dibutylhydroxytoluene (BHT) relative to the total mass of the solids was added to the solids, and the resulting mixture was freeze-milled to obtain a sample of the pulverized material. The freeze-milling conditions were: solids: 3 g, BHT: 0.3 g, Run time: 5 mins, Rate: 15 cps, Cycle: 3. 5 mL of methanol was added to 2.5 g of the obtained pulverized sample. The resulting mixture was subjected to sonication at 50°C for 2 hours and centrifugation (5000 rpm, 5 mins) to settle the copolymer contained in the pulverized sample, and the supernatant was collected as an extract.

[0076] LC-MS analysis was performed on each extract under the following conditions to measure and quantify the content of compound (3) in the extract. Specifically, methanol standard solutions of five levels of compound (3) with known concentrations in the range of 1 to 10,000 ng / g were prepared. From the concentrations of each standard solution and the integral value of the peak area detected by LC-MS analysis, a straight line passing through the origin and represented by the following equation (A1) was derived by a first-order approximation, and the slope a was determined. A = a × x (A1) In equation (A1), A represents the peak area of ​​the detected compound (3), and x represents the concentration of compound (3) (ng / g) relative to the total mass in the methanol standard solution.

[0077] Table 2 below shows the measuring instruments and measurement conditions used for LC-MS analysis. Table 3 below shows the parameters for each compound (3) used in LC-MS analysis using the multiple reaction monitoring (MRM) method.

[0078]

[0079]

[0080] Next, LC-MS analysis by MRM was performed on the extracts prepared from the solids obtained in each example using the method described above, under the conditions described above, using the apparatus described above, to determine the peak area of ​​each compound (3) with a given number of carbon atoms. Subsequently, the content of each compound (3) with a given number of carbon atoms in the extract was calculated using the following formula (A2): XCm = ACm / a (A2) In formula (A2), XCm represents the content (ng / g) of each compound (3) with a given number of carbon atoms in the extract, ACm represents the peak area of ​​each compound (3) with a given number of carbon atoms detected by LC-MS analysis of the extract, and a represents the slope a obtained by formula (A1) above. The limit of quantification in the above LC-MS analysis was 1 ng / g.

[0081] Next, the content of compound (3) relative to the total mass of the solid obtained in each example (ZCm) was determined using the following formula (A3): ZCm = XCm × ρ1 × La / W1 (A3) In formula (A3), ZCm represents the content of compound (3) of each carbon number contained in the solid, ρ1 represents the density of the extraction solvent (methanol in each example), La represents the volume of the extraction solvent (5 mL in each example), and W1 represents the mass of the solid contained in the extract (2.5 g in each example). The content of compound (3) of each carbon number (ZCm) obtained from formula (A3) was summed up to determine the total content of compound (3) in the solid obtained in each example.

[0082] <MFR> For each example, a melt indexer (manufactured by Technoseven Co., Ltd.) was used to measure the mass (g) of the solid that flowed out of a 2 mm diameter, 8 mm length orifice in 10 minutes under ASTM D1238 conditions of a temperature of 372°C and a load of 5 kg, and this was defined as the MFR (g / 10 min).

[0083] [Evaluation Test] <Ozone Resistance> The solid material produced in each example was compressed and molded at 340°C to create a 1 mm thick sheet. The obtained sheets were cut into 10 mm x 20 mm pieces and used as samples for the ozone exposure test.

[0084] A test apparatus was prepared consisting of an ozone generator (product name: SGX-A11MN (modified), manufactured by Sumitomo Seiki Industries Co., Ltd.), a PFA container containing deionized water, and a PFA cell containing the sample, all connected in this order. Ozone gas (ozone / oxygen volume ratio = 10 / 90) generated by the ozone generator was bubbled through deionized water to add water vapor to the ozone gas. The resulting moist ozone gas was then circulated at a rate of 0.7 liters / minute through the PFA cell containing the sample, thereby exposing the sample to the moist ozone gas. During the ozone exposure test, the temperature was maintained at 40°C and the humidity at 80% RH.

[0085] 180 days after the start of the ozone exposure test, the samples were removed and the sample surface was lightly rinsed with deionized water. Then, the sample surface was photographed using a laser microscope, and the number of blisters with a major axis of 1 μm or larger was counted. The major axis of the blister refers to the maximum diameter of the blister as viewed from the normal direction to the sample surface. Based on the number of blisters counted, the ozone resistance of each solid was evaluated according to the following evaluation criteria.

[0086] (Ozone resistance evaluation criteria) ○: Number of blisters is 10 / mm ２ Below ×: Number of blisters: 10 / mm ２ Super

[0087] [Example 1] CF in a 1.2L stainless steel reaction vessel ３ CH ２ OCF ２ CF ２ H (AE-3000: Product name, manufactured by AGC Corporation) (134g), CF ２ = CFO (CF ２ ) ３ F (PPVE) (39.8 g), methanol (36.1 g), ultrapure water (426.7 g), and TFE (142 g) were added, and the mixture was heated to 50°C (polymerization temperature) in the reaction vessel while stirring with a stirring blade. 3 mL of heptafluorobutyroyl peroxide (PFB) (0.06 mass%, AE-3000 solution) was added to the reaction vessel to start polymerization. As the pressure in the reaction vessel decreased after polymerization started, TFE was continuously injected to maintain the pressure at the same level as at the start of polymerization. 2 mL of PFB (0.06 mass%, AE-3000 solution) was added every 10 minutes after the start of polymerization. The polymerization reaction was terminated when the amount of TFE injected reached 160 g, the reaction vessel was cooled, and the remaining TFE was recovered.

[0088] The slurry was removed from the reaction vessel, and the polymerization solvent was recovered using an evaporator. The residue of the obtained slurry was heated at 150°C for 12 hours to obtain a powdered solid X1 containing copolymer X1. １９F-NMR analysis revealed that the composition of copolymer X1 was A / PPVE units = 98.5 / 1.5 mol%. "PPVE units" refer to units based on the PPVE of each copolymer and are included in unit B1. In the analysis of copolymer X1, no units other than PPVE units included in unit B were detected. The number of functional groups N of copolymer X1, determined according to the above measurement method, is 10 carbon atoms in the main chain. ６ Each sample contained more than 500 particles. Furthermore, measurements taken according to the above measurement method revealed that the bulk density of solid X1 was 0.33 g / mL, and the average particle size of solid X1 was 550 μm.

[0089] <Fluorination Treatment> Next, the solid X1 was fluorinated using the following method. The tray containing the solid X1 was placed in a box-type reaction oven and the oven was sealed. After reducing the pressure inside the oven, F ２ The gas is mixed with N to a concentration of 20% by volume. ２ F, which is diluted with gas. ２ / N ２ The mixed gas was introduced into the oven. The pressure inside the oven was set to 1 atmosphere (1 atm), and the temperature inside the oven was set to 230°C. F ２ / N ２ One hour after the introduction of the mixed gas, the oven was depressurized and then F was added again. ２ / N ２ A gas mixture was introduced, and the reaction was carried out at 230°C for 1 hour. After the reaction was complete, heating was stopped, and nitrogen gas was added to the oven. ２ Introducing gas into the oven ２ / N ２ The mixed gas is sufficiently N ２ The fluorination treatment was completed by replacing the gas.

[0090] <Heat Treatment> A mesh tray filled with fluorinated solid material was placed in a box-type reaction oven, and the oven was sealed. The oven was depressurized, and the solid material on the mesh tray was heated at 180°C for 5 hours under a pressure of 1.5 kPa. After heating, the solid material was cooled and N2 was added to the oven. ２ Introducing gas to convert the gas inside the oven to N ２The mixture was purged with gas. The pressure inside the oven was set to 1 atmosphere, and then the oven was opened. The above fluorination treatment and heat treatment yielded a powdery solid Y1 containing copolymer Y1.

[0091] １９ F-NMR analysis revealed that the composition of copolymer Y1 contained in solid Y1 was the same as the composition of copolymer X1. Furthermore, measurements using the above method showed that the number of functional groups N in copolymer Y1 was 10 carbon atoms in the main chain. ６ The amount of compound (3) per solid was less than 50, and the content of compound (3) in solid Y1 was less than 25 mass ppb relative to the total mass of solid Y1. The bulk density and average particle size of solid Y1 were the same as those of solid X1.

[0092] [Example 2] CF in a 1.2L stainless steel reaction vessel ３ CH ２ OCF ２ CF ２ H (AE-3000: Product name, manufactured by AGC Corporation) (80.5g), CF ２ = CFCF ２ OCF ２ CF ２ CF ３ 79.6 g of TFE, methanol (12.1 g), and ultrapure water (426.7 g) were added, and the mixture was heated to 80°C (polymerization temperature). After adding TFE to the reaction vessel until the pressure inside the vessel reached 1.4 MPaG (gauge pressure), 6 mL of tert-butyl peroxypivalate (0.5% by mass, AE-3000 solution) was added, and polymerization was started. As polymerization began, the pressure inside the reaction vessel decreased, so TFE was continuously added to maintain the pressure at the start of polymerization. When the amount of TFE added reached 160 g, the polymerization reaction was stopped, the reaction vessel was cooled, and the remaining TFE was recovered.

[0093] The slurry was removed from the reaction vessel, and the polymerization solvent was recovered using an evaporator. The residue of the obtained slurry was heated at 150°C for 12 hours to obtain a powdered solid X2 containing copolymer X2. １９ ​F-NMR analysis revealed that the composition of copolymer X2 was A / PFAE units = 98.5 / 1.5 mol%. "PFAE units" refer to units based on the PFAE of each copolymer and are included in unit B2. In the analysis of copolymer X2 described above, no units other than PFAE units included in unit B were detected. The number of functional groups N of copolymer X2, determined according to the above measurement method, is 10 carbon atoms in the main chain. ６ Each sample contained more than 500 particles. The bulk density of solid material X2 was 0.33 g / mL, and the average particle size of solid material X2 was 570 μm.

[0094] Except for using solid X2 instead of solid X1, the solid X2 was subjected to fluorination treatment and heat treatment in the same manner as in Example 1 to obtain a powdered solid Y2 containing copolymer Y2. １９ F-NMR analysis revealed that the composition of copolymer Y2 contained in solid Y2 was the same as that of copolymer X2. Furthermore, measurements using the above method showed that the number of functional groups N in copolymer Y2 was 10 carbon atoms in the main chain. ６ The amount of compound (3) per solid was less than 50, and the content of compound (3) in solid Y2 was less than 25 mass ppb relative to the total mass of solid Y2. The bulk density and average particle size of solid Y2 were the same as those of solid X2.

[0095] [Example 3] A powdery solid X1 containing copolymer X1 was obtained according to the method described in Example 1. The obtained solid X1 was pelletized using an extruder. Specifically, a twin-screw coaxial extruder was prepared, equipped with a screw having two kneading sections. The solid X1 was placed in the hopper of the feeder of the twin-screw extruder, and the solid X1 was kneaded under conditions of a cylinder temperature of 380°C and a screw rotation speed of 100 rpm, while the vent section was sucked with a vacuum pump. The strand discharged from the vent section was slowly cooled and cut with a pelletizer to produce pellet-shaped solid X3 containing copolymer X1. The shape of the solid X3 was cylindrical with a length of 5 mm or less and a length-to-diameter ratio (length / diameter) of 0.5 or more and less than 1.5.

[0096] １９ ​F-NMR analysis revealed that the composition and number of functional groups N of copolymer X1 contained in solid X3 were the same as those of copolymer X1 contained in solid X1. Furthermore, the bulk density of solid X3 was 1.26 g / mL.

[0097] The obtained solid X3 was subjected to a fluorination treatment according to the fluorination treatment method described in Example 1 to obtain pellet-shaped solid Y3 containing copolymer Y3. １９ F-NMR analysis revealed that the composition of copolymer Y3 was the same as that of copolymer X1 contained in solid X3. Furthermore, measurements using the above method showed that the number of functional groups N in copolymer Y3 was 10 carbon atoms in the main chain. ６ The amount per unit was less than 50, and the content of compound (3) in solid Y3 was 5000 ppb by mass relative to the total mass of solid Y3.

[0098] [Example 4] Except for using pelletized solid X3 produced in Example 3 instead of solid X1, the solid X3 was subjected to fluorination treatment and heat treatment in the same manner as in Example 1 to obtain pelletized solid Y4 containing copolymer Y4. １９ F-NMR analysis revealed that the composition of copolymer Y4 was the same as that of copolymer X1 contained in solid X3. Furthermore, measurements using the above method showed that the number of functional groups N of copolymer Y4 was 10 carbon atoms in the main chain. ６ The amount per unit was less than 50, and the content of compound (3) in solid Y4 was 3000 ppb by mass relative to the total mass of solid Y4.

[0099] [Example 5] A powdered solid Y1 containing copolymer Y1 was obtained according to the method described in Example 1. Next, the obtained solid Y1 was pelletized using an extruder according to the pelletization method for solid X1 in Example 3. This produced pelletized solid Y5 containing copolymer Y5. The shape of the solid Y5 was cylindrical with a length of 5 mm or less and a length-to-diameter ratio (length / diameter) of 0.5 or more and less than 1.5. The composition and number of functional groups N of copolymer Y5 contained in solid Y5 were the same as those of copolymer Y1 contained in solid Y1. In addition, the content of compound (3) contained in solid Y5 was the same as the content of compound (3) contained in solid Y1.

[0100] [Example 6] A powdered solid Y6 containing copolymer Y6 was obtained in the same manner as in Example 1, except that only a fluorination treatment was performed on the obtained powdered solid X1 and no heat treatment was performed. １９ F-NMR analysis revealed that the composition of copolymer Y6 contained in solid Y6 was the same as that of copolymer X1. Furthermore, measurements using the above method showed that the number of functional groups N in copolymer Y6 was 10 carbon atoms in the main chain. ６ The amount of compound (3) per solid was less than 50, and the content of compound (3) in solid Y6 was 5500 mass ppb relative to the total mass of solid Y6. The bulk density and average particle size of solid Y6 were the same as those of solid X1, respectively.

[0101] [Example 7] A powdered solid X1 containing copolymer X1 was obtained according to the method described in Example 1. <Fluorination Treatment> Next, the solid X1 was fluorinated by the following method. The tray on which the solid X1 was placed was placed in a box-type reaction oven and the oven was sealed. After reducing the pressure inside the oven, F ２ The gas is mixed with N to a concentration of 20% by volume. ２ F, which is diluted with gas. ２ / N ２ The mixed gas was introduced into the oven. The pressure inside the oven was set to 1 atmosphere (1 atm), and the temperature inside the oven was set to 190°C. F ２ / N ２ One hour after the introduction of the mixed gas, the oven was depressurized and then F was added again. ２ / N２ A gas mixture was introduced, and the reaction was carried out at 190°C for 1 hour. After the reaction was complete, heating was stopped, and nitrogen gas was added to the oven. ２ Introducing gas into the oven ２ / N ２ The mixed gas is sufficiently N ２ The fluorination treatment was completed by replacing the gas.

[0102] <Heat Treatment> A mesh tray filled with fluorinated solid material was placed in a box-type reaction oven, and the oven was sealed. The oven was depressurized, and the solid material on the mesh tray was heated at 180°C for 5 hours under a pressure of 1.5 kPa. After heating, the solid material was cooled and N2 was added to the oven. ２ Introducing gas to convert the gas inside the oven to N ２ The mixture was purged with gas. The pressure inside the oven was increased to 1 atmosphere, and then the oven was opened. The above fluorination treatment and heat treatment yielded a powdery solid Z1 containing copolymer Z1.

[0103] １９ F-NMR analysis revealed that the composition of copolymer Y1 contained in solid Z1 was the same as that of copolymer X1. Furthermore, measurements using the above method showed that the number of functional groups N in copolymer Z1 was 10 carbon atoms in the main chain. ６ Each solid contained more than 150 particles, and the amount of compound (3) contained in solid Z1 was less than 25 mass ppb relative to the total mass of solid Y1. The bulk density and average particle size of solid Z1 were the same as those of solid X1.

[0104] The table below shows the copolymer composition, solid material properties, and evaluation results for each example. The "Number of Functional Groups N" column indicates the total number of specific functional groups in copolymer X contained in solid material X or copolymer Y contained in solid material Y. For example, the notation "500≦" in the "Number of Functional Groups N" column for "Copolymer X" in Example 1 indicates that copolymer X1 has 10 carbon atoms in its main chain. ６ This means that the total number of specific functional groups per unit was 500 or more, and the notation "<50" in the "Number of Functional Groups N" column for "Copolymer Y" indicates that the main chain carbon number of copolymer Y1 is 10 ６ ​This means that the total number of specific functional groups per unit was less than 50. The "Unit A (mol%)" column, the "Unit B1 (mol%)" column, and the "Unit B2 (mol%)" column show the content of Unit A (unit: mol%), Unit B1 (unit: mol%), and Unit B2 (unit: mol%) relative to the total units contained in the copolymer, respectively. The "Compound (3) (mass ppb)" column for "Solid Y" shows the content of Compound (3) (mass ppb) relative to the total mass of Solid Y.

[0105] In each example, the content of units A, B1, and B2 of copolymer X contained in solid X before fluorination treatment was the same as the content of units A, B1, and B2 of copolymer Y contained in solid Y after fluorination treatment.

[0106]

[0107] As shown in the table above, a powdered or pelletized solid containing a copolymer containing unit A and unit B, wherein the number of functional groups N is 10 carbon atoms in the main chain of the copolymer. ６ It has been confirmed that by using the solid material of the present invention, which contains fewer than 150 particles per unit and substantially does not contain compound (3), it is possible to form molded articles that are less prone to ozone-induced blistering and have excellent ozone resistance (Examples 1, 2, and 5). The entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2024-203142, filed on November 21, 2024, are incorporated herein by reference as disclosure of the present invention.

Claims

1. A solid in powder or pellet form, comprising a copolymer containing a unit A based on tetrafluoroethylene and a unit B based on a monomer selected from the group consisting of the monomer represented by formula (1) and the monomer represented by formula (2), wherein the total number of functional groups of -CF=CF ｎ－１ , ３ , ２ , ｎ , ３ , ２ 、-CF ２ H, -COF, -COOH, -COOCH ３ 、-CONH ２ and -CH ２ OH is less than 150 per 10 ６ main-chain carbon atoms of the copolymer, and substantially free of the compound represented by formula (3). Formula (1) CF ２ =CF-O-(CF ２ ) ｎ -CF ３ Formula (2) CF ２ =CF-CF ２ -O-(CF ２ ) ｎ -CF ３ Formula (3) CF ３ -(CF ２ ) ｎ－１ -COOH In formulas (1) to (3), n represents 1 to 9.

2. The solid according to claim 1, wherein the content of unit A is 95.0 to 99.5 mol% relative to the total units of the copolymer.

3. The solid according to claim 1, wherein the content of unit A is 97.0 to 99.5 mol% relative to the total units of the copolymer.

4. The solid according to claim 1, wherein the content of unit B is 0.5 to 5.0 mol% relative to the total units of the copolymer.

5. The solid according to claim 1, wherein the melt flow rate of the copolymer, measured under conditions of a temperature of 372°C and a load of 5 kg in accordance with ASTM D1238, is 1.0 to 50.0 g / 10 min.

6. The solid according to claim 1, wherein unit B comprises at least one selected from the group consisting of units based on perfluoro(propyl vinyl ether) and units based on perfluoro(propyl allyl ether).

7. A molded article characterized by being obtained by molding a solid material according to any one of claims 1 to 6.

8. A powdered solid containing a copolymer comprising unit A based on tetrafluoroethylene and unit B based on a monomer selected from the group consisting of monomers represented by formula (1) and monomers represented by formula (2) is fluorinated, and the fluorinated powdered solid is heated at 100 to 250°C for 1 hour or more to obtain a copolymer containing unit A and unit B, wherein the total number of functional groups of the copolymer has 10 carbon atoms in the main chain. ６ A method for producing a solid, characterized by obtaining a powdered or pelletized solid containing a copolymer with fewer than 150 units per unit. Formula (1) CF ２ =CF - O - (CF ２ ) ｎ -CF ３ Formula (2) CF ２ = CF - CF ２ -O-(CF ２ ) ｎ -CF ３ In equations (1) and (2), n represents a value between 1 and 9.

9. The bulk density of the powdered solid subject to the fluorination treatment is 0.10 to 0.70 g / cm³. ３ The method for producing a solid substance according to claim 8.

10. A method for producing a solid according to claim 8 or 9, wherein the fluorinated powdered solid is heated under reduced pressure of 2.0 kPa or less.

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