Solid matter, formed body, and method for manufacturing solid matter

Abstract

An object of the present invention is to provide a solid substance, a molded article, and a method for producing the solid substance, which can form a molded article that is less likely to generate blisters due to ozone and has excellent ozone resistance. 【Solution means】The solid substance of the present invention is a powdery or pelletized solid substance 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 formula (1) (CF2=CF-O-(CF2) n -CF3) and a monomer represented by the formula (2) (CF2=CF-CF2-O-(CF2) n -CF3), wherein the total number of functional groups of -CF=CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2, and -CH2OH is less than 150 per 10 main chain carbons of the copolymer, and substantially does not contain a compound represented by the formula (3) (CF3-(CF2) 6 -COOH). n-1 ​

Description

Technical Field

[0001] The present invention relates to a solid, a molded body, and a method for manufacturing a solid.

Background Art

[0002] As a fluororesin having excellent mechanical properties, chemical properties, electrical properties, etc. and being melt-processable, a copolymer of tetrafluoroethylene and perfluoro(alkyl vinyl ether) (hereinafter also referred to as "PFA") is known. For example, Patent Document 1 discloses a copolymer containing tetrafluoroethylene units and perfluoro(propyl vinyl ether) units, and having a functional group number of 50 or less per 10 main chain carbon atoms. 6

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Recently, when a molded body of PFA is used as a pipe material for semiconductor manufacturing equipment, the molded body is required to have an even further improved ozone resistance. When the present inventors evaluated a molded body formed using the copolymer produced in Patent Document 1, they found that the ozone resistance did not meet the higher required level currently demanded, and further improvement was necessary.

[0005] In view of the above problems, an object of the present invention is to provide a solid that can form a molded body excellent in ozone resistance and difficult to generate blisters due to ozone. Another object of the present invention is to provide a method for manufacturing a molded body and a solid.

Means for Solving the Problems

[0006] As a result of intensive studies on the above problems, the present inventors have found that a solid in powder or pellet form 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 total number of functional groups of -CF=CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2, and -CH2OH in the copolymer is less than 150 per 10 carbon atoms of the copolymer 6 and the solid substantially does not contain a compound represented by a specific formula (3), and have 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 solid in powder or pellet form 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, wherein the total number of functional groups of -CF=CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2, and -CH2OH is less than 150 per 10 main-chain carbon atoms of the copolymer 6 and the solid substantially does not contain a compound represented by formula (3) described later. 〔2〕 The solid according to 〔1〕, wherein the content of the unit A is 95.0 to 99.5 mol% based on all the units of the copolymer. 〔3〕 The solid according to 〔1〕 or 〔2〕, wherein the content of the unit B is 0.5 to 5.0 mol% based on all the units of the copolymer. 〔4〕 The solid according to any one of 〔1〕 to 〔3〕, wherein the melt flow rate of the copolymer measured under the 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. [5] The solid material according to any one of [1] to [4], wherein the unit B includes at least one selected from the group consisting of a unit based on perfluoro(propyl vinyl ether) and a unit based on perfluoro(propyl allyl ether). [6] A molded product obtained by molding the solid material according to any one of [1] to [5]. [7] A powdered 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 formula (1) described later and a monomer represented by the formula (2) described later is fluorinated, and the fluorinated powdered solid material is heated at 100 to 250°C for 1 hour or more to obtain a copolymer containing the unit A and the unit B, wherein the total number of the functional groups is equal to or greater than 10 main chain carbon atoms of the copolymer. 6 A method for producing a solid material, comprising obtaining a powdered or pelletized solid material containing a copolymer having less than 150 units per pellet. [8] The powdered solid material to be subjected to the fluorination treatment has a bulk density of 0.10 to 0.70 g / cm 3 The method for producing a solid material according to [7], [9] The method for producing a solid material according to [7] or [8], wherein the fluorination-treated powdered solid material is heated under a reduced pressure of 2.0 kPa or less. Effect of the Invention

[0008] According to the present invention, it is possible to provide a solid material capable of forming a molded body having excellent ozone resistance and being less susceptible to blistering due to ozone. Also, according to the present invention, it is possible to provide a method for producing the molded body and the solid material. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The terms used in this specification have the following meanings: A numerical range expressed using "~" means that the range includes the numerical values ​​before and after "~" as the lower and upper limits.

[0010] The term "unit" is a general term for an atomic group directly formed by polymerization of a monomer and derived from one molecule of the monomer, and an atomic group obtained by chemically converting a part of the atomic group. In the following, in some cases, the unit derived from each monomer is denoted by a name obtained by attaching "unit" to the monomer name. "Unit A" is a unit based on tetrafluoroethylene contained in the copolymer. "Monomer B1" is a monomer represented by formula (1) described later, "Monomer B2" is a 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 a unit based on Monomer B, a unit based on Monomer B1, and a unit based on Monomer B2, respectively, contained in the copolymer.

[0011] The "specific functional group" means a functional group contained in the group consisting of -CF=CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2 and -CH2OH. The "number of functional groups" means the total number of specific functional groups that the copolymer has, unless otherwise specified.

[0012] The "solid matter" means a composition that is solid at 25°C. The "powdered solid matter" means an object having an average particle diameter of 3000 μm or less and a bulk density of 0.10 to 0.80 g / cm 3 . The "pelletized solid matter" means a particulate molded article produced by a method of extruding and cutting a solid matter. The pressure in this specification is the absolute pressure.

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

[0014] By using such a present solid matter, a molded article excellent in ozone resistance, in which blisters due to ozone hardly occur, can be formed. Although the details of this reason have not yet been clarified, it is presumed to be due to the following reasons. As a result of intensive studies, the present 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 a molded article formed using PFA. When ozone having a strong oxidizing power contacts the compound (3) contained in the molded article, it is presumed that the carboxylic acid site of the compound (3) is decomposed by ozone and CO2 is desorbed (decarboxylation reaction), and foaming (blisters) occurring on the surface of the molded article is caused by the generated CO2. Further, it is presumed that after the carboxylic acid site in the compound (3) is decomposed, the -CF2- group reacts with ozone to generate hydrofluoric acid, and this hydrofluoric acid also contributes to the generation of foaming. The compound (3) in question is presumed to be generated in the production process of PFA, particularly when PFA is fluorinated. On the other hand, by using a powdery or pelletized solid matter containing a copolymer containing unit A and unit B and substantially not containing the compound (3), it is presumed that the generation of CO2 and hydrofluoric acid upon contact with ozone is suppressed, and a molded article with improved ozone resistance can be formed. Further, by fluorinating a powdery solid matter having 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, it is presumed that a molded article substantially not containing the compound (3) and having similarly improved ozone resistance can be formed. Further, when the total number of specific functional groups possessed by the copolymer is less than 150 per 10 main chain carbon atoms of the copolymer, it is presumed that oxidative decomposition of the specific functional groups by ozone is suppressed. 6 Thus, it is presumed that by satisfying each requirement, a molded article excellent in ozone resistance can be obtained.

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

[0016] <the present copolymer> The present 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%, based on all the units contained in the present copolymer, in terms of more excellent 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). CF2=CF-O-(CF2) n -CF3(1) CF2=CF-CF2-O-(CF2) n -CF3(2) In formula (1) and formula (2), n represents 1 to 9. In formula (1) and formula (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 more excellent 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). Among them, perfluoro(methyl allyl ether), perfluoro(ethyl allyl ether), or PFAE is preferred, and PFAE is more preferred.

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

[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% with respect to all units contained in the present copolymer in terms of better moldability and mechanical properties. The present copolymer may contain two or more types of unit B. When the present 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 the present 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% with respect to all units contained in the present copolymer because the resulting molded article is less likely to be deformed easily by compression or tension.

[0023] The present copolymer may contain, in addition to unit A and unit B, units based on TFE and other monomers copolymerizable with monomer B. Examples of other monomers include, for example, ethylene, vinylidene fluoride (VdF), hexafluoropropylene (HFP), CX1 X 2 =CX 3 (CF2) n X 4 (wherein 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.) monomer, and CF2=CF-OCH2-Rf 2 (wherein Rf 2 represents a perfluoroalkyl group having 1 to 5 carbon atoms.) monomer. When the copolymer contains units based on other monomers, the content of the units based on other monomers is preferably less than 4.5 mol%, preferably less than 2.5 mol%, more preferably less than 1.0 mol%, and particularly preferably less than 0.5 mol% with respect to all the units contained in the copolymer.

[0024] From the viewpoint of more excellent abrasion resistance during repeated use, the copolymer preferably does not contain units based on the above other monomers and contains only unit A and unit B. In this case, the total content of unit A and unit B is 100.0 mol% with respect to all the units contained in the copolymer.

[0025] The respective contents of unit A, unit B and units based on other monomers in the copolymer can be measured by a known method such as the F-NMR (nuclear magnetic resonance analysis) method. 19 F-NMR (nuclear magnetic resonance analysis) method and other known methods.

[0026] (Number of functional groups) In the copolymer, the total number of specific functional groups included in the group consisting of -CF=CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2 and -CH2OH is less than 150 per 10 carbon atoms of the copolymer. 6 per. From the viewpoint of forming a molded article with more excellent 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] The specific functional group is a functional group present at the terminal of the main chain or side chain of the copolymer, and a functional group present in the main chain or side chain, and the number of functional groups is the total number of specific functional groups. The specific functional group is introduced into the copolymer, for example, by a chain transfer agent or a polymerization initiator used in the production of the copolymer. More specifically, when an alcohol is used as the chain transfer agent, or when a peroxide having a -CH2OH structure is used as the polymerization initiator, -CH2OH is introduced at the terminal of the main chain of the copolymer. Further, by polymerizing a monomer having a functional group, the above functional group is introduced at the terminal of the side chain of the copolymer. Also, when the number of functional groups of the copolymer having a specific functional group exceeds a predetermined range, the copolymer can be fluorinated to convert the specific functional group into a -CF3 terminal group, thereby reducing the number of functional groups. By changing the conditions (for example, treatment time, etc.) of the fluorination treatment described later, the number of functional groups of the copolymer can be adjusted.

[0028] Infrared spectroscopy can be used to identify the type of functional group and measure the number of functional groups in the copolymer. Specifically, the number of functional groups is measured by the following method. First, the copolymer is molded by a hot press at 330 °C to produce a film having 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 above copolymer. Separately, an infrared absorption spectrum (base spectrum) that is completely fluorinated and has no specific functional group is obtained, and a difference spectrum between the infrared absorption spectrum of the above copolymer and the base spectrum is obtained. From the absorption peak of the specific functional group appearing in this difference spectrum, according to the following formula (A), the number of functional groups N per 10 carbon atoms in the above copolymer 6 is calculated.

[0029] N = I × K / t (A) I: Absorbance K: Correction coefficient t: Thickness of the film (mm)

[0030] Table 1 shows the absorption frequency, molar extinction coefficient, and correction coefficient for specific functional groups. The molar extinction coefficient of a specific functional group is determined from the FT-IR (Fourier transform infrared spectroscopy) measurement data of a low molecular weight model compound.

[0031]

Table 1

[0032] In the copolymer, the absorption frequencies of -CH2CF2H, -CH2COF, -CH2COOH, -CH2COOCH3, and -CH2CONH2 are several tens of wavenumbers (cm -1 ) lower than the respective absorption frequencies of -CF2H, -COF, -COOH (free and bonded), -COOCH3, and -CONH2 shown in the table. For example, the number of -COF is the sum of the number of functional groups determined from the absorption peak of the absorption frequency 1883 cm -1 attributed to -CF2COF and the number of functional groups determined from the absorption peak of the absorption frequency 1840 cm -1 attributed to -CH2COF.

[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 that a molded article with excellent balance of folding resistance and bending strength can be formed. As a specific example of the method for making the MFR of this copolymer within the above range, a method for adjusting the molecular weight of this copolymer can be mentioned. The larger the molecular weight of this copolymer, the smaller the MFR. The MFR of the copolymer means the mass (g) of the copolymer flowing out in 10 minutes from an orifice with a diameter of 2 mm and a length of 8 mm, measured under the conditions of a temperature of 372 °C and a load of 5 kg in accordance with ASTM D1238. In addition, since this copolymer is the main component of the solid content and the influence of components other than this copolymer on the measurement of MFR is almost negligible, the measured value of MFR obtained by measuring the solid content can be regarded 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. As a specific example of the method for making the melting point of this copolymer within the above range, a method of adjusting the composition of this copolymer can be mentioned. The melting point of this copolymer is the temperature corresponding to the endothermic peak when the copolymer is heated, with the temperature rising at 10 °C / min in an air atmosphere using a differential scanning calorimeter.

[0035] This solid may contain other components other than this copolymer. Specific examples of such other components include other resins other than this copolymer, 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 with respect to 100 parts by mass of this copolymer.

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

[0037] When the solid substance is in the form of pellets, a particulate molded body having a diameter or length of about 1 to 10 mm of the solid substance is preferred. The shape of the pellet-shaped solid substance is not limited, but is usually spherical, ellipsoidal or cylindrical.

[0038] The solid substance does not substantially contain the compound represented by the following formula (3) (compound (3)). Formula (3) CF3-(CF2) n-1 -COOH In formula (3), n represents 1 to 9.

[0039] In this specification, "the solid substance does not substantially contain the compound represented by formula (3)" means that the content of compound (3) in the solid substance (the total content when two or more compounds (3) are included. The same shall apply hereinafter.) is less than 250 mass ppb with respect to the total mass of the solid substance. The content of compound (3) in the solid matter is preferably less than 150 mass ppb, more preferably less than 25 mass ppb, based on the total mass of the solid matter. The content of compound (3) may be 0 mass ppb based on the total mass of the solid matter.

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

[0041] The content of compound (3) contained in the solid matter can be reduced, for example, by subjecting a powdery solid matter having a bulk density in a specific range to a fluorination treatment when producing the solid matter, and further subjecting the fluorinated powdery solid matter to a heat treatment. Details of the fluorination treatment and heat treatment in the production of the solid matter are described below.

[0042] In this solid matter, from the viewpoint of more excellent ozone resistance of the molded body formed from this solid matter, the content of the second copolymer containing unit A and the unit based on hexafluoropropylene and not containing unit B is preferably less than 0.5 mass% with respect to the total of the content of this copolymer and the content of the second copolymer, and more preferably 0 mass%. Note that "not containing unit B" means that the content of unit B with respect to all units of the copolymer is 0.5 mol% or less.

[0043] <Method for producing solid matter> Examples of the method for producing this solid matter include a method of producing a copolymer, subjecting the powdery solid matter containing the produced copolymer to a fluorination treatment, and subjecting the fluorinated powdery solid matter to a heat treatment. Taking the above method as an example, the method for producing this solid matter will be described.

[0044] As a process for producing the copolymer, there are processes for producing by known methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization using the above monomers (TFE and monomer B), and a process for producing by solution polymerization is preferred. In the production of the copolymer, in addition to the above monomers, a polymerization initiator, a polymerization medium, a chain transfer agent, etc. can be used.

[0045] The polymerization initiator is preferably a radical polymerization initiator having a half-life of 10 hours at a temperature of 0 to 100 ° C, and more preferably a radical polymerization initiator having the above temperature of 20 to 90 ° C. Specific examples of the polymerization initiator include 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 the polymerization initiator used is preferably 0.01 to 0.9 parts by mass, and more preferably 0.05 to 0.5 parts by mass with respect to 100 parts by mass of the amount of the monomer used.

[0046] Examples of the polymerization medium include water, an organic solvent, and a mixed solvent of water and an organic solvent. As the organic solvent, fluorine-based solvents such as perfluorocarbon, hydrofluorocarbon, and hydrofluoroether can be used. Specific examples of the organic solvent include the polymerization media exemplified in International Publication No. 2013 / 015202. As the polymerization medium, a polymerization medium containing water is preferred, and ultrapure water is more preferred.

[0047] The polymerization medium may be used alone or in combination of two or more. As the polymerization medium, a mixed solvent of water and a fluorine-based solvent is preferred, and a mixed solvent of water and perfluorocarbon is more preferred. The amount of the fluorine-based solvent used is preferably 10% by mass or more and less than 100% by mass with respect to the total mass of the mixed solvent from the viewpoints of suspension and economy. The amount of the polymerization medium used is preferably 3 times or more, more preferably 5 times or more, in terms of mass ratio with respect to the amount of the monomer used. Also, it is preferably 20 times or less, more preferably 17 times or less.

[0048] As the chain transfer agent, from the viewpoints that the chain transfer constant is large and the addition amount can be small, alcohols such as methanol, ethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoropropanol, 1,1,1,3,3,3-hexafluoroisopropanol and 2,2,3,3,3-pentafluoropropanol; hydrocarbons such as n-pentane, n-hexane and cyclohexane; 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 them, at least one selected from the group consisting of alcohols, hydrocarbons and hydrofluorocarbons is preferred from the viewpoints that the chain transfer constant is higher and the stability of the end groups of the copolymer is high, at least one selected from the group consisting of alcohols and hydrocarbons is more preferred, and alcohols are even more preferred. As the alcohols, methanol or ethanol is preferred, and methanol is more preferred from the viewpoints of reactivity and availability. Two or more kinds of chain transfer agents may be used. The usage amount of the chain transfer agent is preferably 0.001 times or more, more preferably 0.005 times or more, by mass ratio with respect to the usage amount of the monomer. Also, it is preferably 5 times or less, more preferably 4 times or less.

[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, more preferably 0.9 to 2.5 MPa. The polymerization time is preferably 1 to 12 hours.

[0050] When an aqueous dispersion containing a copolymer is obtained by coincidence, the copolymer contained in the aqueous dispersion can be recovered by coagulating, washing, and drying the copolymer. Also, when the copolymer is obtained as a slurry by polymerization, the copolymer can be recovered by taking out the slurry from the reaction vessel, washing, and drying it.

[0051] Next, the powdery solid containing the obtained copolymer is fluorinated. The powdery solid to be subjected to the fluorination treatment contains the above copolymer. The bulk density of the powdery solid to be subjected to the fluorination treatment is 0.10 to 0.80 g / cm 3 and, in terms of more excellent end-treatment efficiency, 0.10 to 0.75 g / cm 3 is preferable, 0.10 to 0.70 g / cm 3 is more preferable, 0.15 to 0.70 g / cm 3 is even more preferable, 0.20 to 0.70 g / cm 3 is particularly preferable.

[0052] When the copolymer obtained by polymerization is a powdery solid, it may be directly fluorinated with respect to the recovered copolymer. If necessary, the copolymer obtained by polymerization may be pulverized to produce a powdery solid. The pulverization treatment can be performed using a known pulverizer such as a rotor mill, a hammer mill, a turbo mill, or a jet mill.

[0053] Also, a composition such as a pellet-shaped solid or a granulated product containing the copolymer obtained by polymerization may be produced, and the obtained composition may be pulverized to produce a powdery solid. The pellet-shaped solid can be formed by a conventionally known method. Examples of the method for forming the pellet-shaped solid include a method of extruding while melting the copolymer fluorinated using a single-screw extruder, a twin-screw extruder, and a tandem extruder, and cutting it into a predetermined length to form it into a pellet shape. The extrusion temperature in melt extrusion is appropriately changed depending on the melt viscosity of the copolymer and the manufacturing method, but it is preferably +20°C to the melting point of the copolymer to +140°C relative to the melting point of the copolymer. As the method for cutting the copolymer, conventionally known methods such as the strand cut method, the hot cut method, the underwater cut method, and the sheet cut method can be adopted.

[0054] (Fluorination treatment) Next, as the fluorination treatment, a fluorinating agent is brought into contact with a powdery solid containing the copolymer obtained by polymerization. By the fluorination treatment, specific functional groups of the copolymer, which consist of -COOH, -COOCH3, -CH2OH, -COF, -CF=CF2, -CONH2, and -CF2H, can be converted to -CF3. Thereby, 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] Examples of the fluorinating agent include fluorine radical sources that generate fluorine radicals under fluorination treatment conditions. Examples of the above fluorine radical sources include F2 gas, N2F2, and halogen fluorides (for example, IF5 and ClF3). The concentration of a 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 with an inert gas so that the concentration of F2 gas is 5 to 50% by volume (more preferably 15 to 30% by volume). Examples of the above inert gas include nitrogen gas, helium gas, and argon gas, and nitrogen gas is preferable from the viewpoint of economy.

[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 is, for example, 0.5 to 30 hours, and preferably 1 to 24 hours. 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 method may be mentioned in which a tray with a powdery solid placed therein is installed in an oven, the inside of the oven is filled with F2 gas or the above-mentioned mixed gas, and heated for a certain period of time. Further, a method may also be mentioned in which while heating a flow-through column filled with a powdery solid, F2 gas or the above-mentioned mixed gas is allowed to flow through the flow-through column for a certain period of time. From the viewpoint of reaction efficiency, as a method of the fluorination treatment, a method in which a tray with a powdery solid placed therein is installed in an oven, the inside of the oven is filled with F2 gas or the above-mentioned mixed gas, and heated for a certain period of time is preferable.

[0058] (Heat treatment) Next, the fluorinated powdery solid is heat-treated. In terms of being able to more easily manufacture this solid, it is preferable to heat the fluorinated powdery solid at 100 to 250 °C for 1 hour or more.

[0059] As a specific method of the heat treatment, for example, a method may be mentioned in which a tray with the fluorinated solid placed therein is installed in an oven and heated. The temperature of the heat treatment is more preferably 100 to 250 °C, and even more preferably 150 to 200 °C. The treatment time of the heat treatment is more preferably 1 to 15 hours, and even more preferably 3 to 10 hours. The heat treatment may be carried out under atmospheric pressure, but it is preferably carried out under reduced pressure. From the viewpoint of removal efficiency, the pressure when carrying out the heat treatment under reduced 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 heating efficiency, the pressure when carrying out the heat treatment under reduced pressure is preferably 0 kPa or more.

[0060] The solid obtained by the above-mentioned fluorination treatment and heat treatment may be a powdery form of this solid. Further, the powdery or pelletized form of this solid may also be a solid produced by performing known treatments such as the above-mentioned pelletization treatment and pulverization treatment on the solid obtained by the above-mentioned fluorination treatment and heat treatment.

[0061] [Second Embodiment: Method for Producing Solid Substance] The method for producing a solid substance according to the second embodiment of the present invention (hereinafter also referred to as "this production method") fluorinates a powdery solid substance containing a copolymer including unit A and unit B, and heats the fluorinated powdery solid substance at 100 to 250°C for 1 hour or more to obtain a copolymer including unit A and unit B, in which the total number of specific functional groups is less than 150 per 10 main-chain carbon atoms of the copolymer, and a powdery or pellet-shaped solid substance containing the copolymer is obtained. This is a method for producing a solid substance. 6 By this production method, a powdery or pellet-shaped solid substance containing a copolymer including unit A and unit B, which can form a molded body having excellent ozone resistance, can be produced.

[0062] Regarding the powdery solid substance to be subjected to the fluorination treatment and the copolymer contained in the solid substance in this production method, except for the bulk density, including preferred embodiments, it is as described for the solid substance and the copolymer contained in the solid substance before the fluorination treatment in the first embodiment. The bulk density of the powdery solid substance to be subjected to the fluorination treatment in this production method is 0.10 to 0.80 g / cm 3 , and in terms of more excellent heating efficiency, 0.10 to 0.75 g / cm 3 is preferred, 0.10 to 0.70 g / cm 3 is more preferred, 0.15 to 0.70 g / cm 3 is further preferred, and 0.20 to 0.70 g / cm 3 is particularly preferred. Also, the number of functional groups in the copolymer contained in the powdery solid substance to be subjected to the fluorination treatment in this production method is usually 150 or more per 10 main-chain carbon atoms of the copolymer. 6

[0063] Regarding the method for fluorinating the powdery solid substance in this production method, including preferred embodiments, it is as already described for the fluorination treatment of the method for producing a solid substance according to the first embodiment.

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

[0065] The solid obtained by the above fluorination treatment and heat treatment may be a powdery solid. Further, a powdery or pelletized solid may be produced by performing known treatments such as pelletization treatment and pulverization treatment on the solid (preferably a powdery solid) obtained by the above fluorination treatment and heat treatment. Regarding the pelletization treatment and pulverization treatment, including preferred embodiments, they are as described respectively in the method for manufacturing a solid according to the first embodiment.

[0066] The solid produced by this manufacturing method preferably does not substantially contain compound (3). That is, the content of compound (3) in the solid produced by this manufacturing method (the total content when two or more kinds of compound (3) are included) is preferably less than 250 mass ppb with respect to the total mass of the solid. By manufacturing a solid by this manufacturing method, it is easy to obtain a solid that does not substantially contain compound (3). The content of compound (3) in the solid produced by this production method is more preferably less than 150 mass ppb, and even more preferably less than 25 mass ppb, based on the total mass of the solid. The content of compound (3) may be 0 mass ppb based on the total mass of the solid. Regarding other properties of the solid produced by this production method, including preferred embodiments, they are as described for the solid according to the first embodiment.

[0067] [Formed body] The formed body of the present invention is obtained by molding the solid according to the first embodiment of the present invention or the solid produced by the production method according to the second embodiment of the present invention. Specific examples of the formed body of the present invention include an injection molded body obtained by injection molding a solid, an extrusion molded body obtained by extrusion molding, a blow molded body obtained by blow molding, a transfer molded body obtained by transfer molding, a press molded body obtained by press molding, a rotational molded body obtained by rotational molding, and a coating film obtained by electrostatic coating. The formed body of the present invention is preferably a press molded body obtained by press molding. Also, an injection molded body is also preferable because an injection molded body with a beautiful appearance can be obtained without corroding the mold used for molding.

[0068] Specific examples of the formed body of the present invention include nuts, bolts, joints, films, bottles, gaskets, wire coating materials, tubes, hoses, pipes, valves, sheets, seals, packings, tanks, rollers, containers, cocks, connectors, filter housings, filter cages, flow meters, pumps, wafer carriers, and wafer boxes.

[0069] This solid, the solid produced by the production method according to the second embodiment, or the formed body of the present invention can be used for the following applications. Food packaging films, lining materials for fluid transfer lines used in food manufacturing processes, packings, sealing materials, and fluid transfer members for food manufacturing equipment such as sheets; medicine plugs for pharmaceuticals, packaging films, lining materials for fluid transfer lines used in pharmaceutical manufacturing processes, packings, sealing materials, and chemical liquid transfer members such as sheets; inner surface lining members for chemical liquid tanks and pipes in chemical plants or semiconductor factories; O-ring (angle) rings, tubes, packings, valve core materials, hoses, and sealing materials used in the fuel systems and peripheral devices of automobiles, and fuel transfer members such as hoses and sealing materials used in the AT devices of automobiles; flange gaskets for carburetors, shaft seals, valve stem seals, sealing materials, and hoses used in the engines and peripheral devices of automobiles, and other automotive members such as automotive brake hoses, air conditioner hoses, radiator hoses, and wire coatings; O-ring (angle) rings, tubes, packings, valve core materials, hoses, sealing materials, rolls, gaskets, diaphragms, and joints used in semiconductor manufacturing equipment for chemical liquid transfer members of semiconductor devices; coating rolls, hoses, tubes, and ink containers for coating equipment and other coating and ink members; tubes, hoses, belts, packings, and joints for food and beverage transfer members such as tubes or hoses for food and beverages, food packaging materials, and glass cooking utensils; waste liquid transfer members such as tubes and hoses for waste liquid transportation; high-temperature liquid transfer members such as tubes and hoses for high-temperature liquid transportation; steam piping members such as tubes and hoses for steam piping; anticorrosive tapes for piping such as tapes wound around pipes on the decks of ships; various coating materials such as wire coatings, optical fiber coatings, transparent surface coatings and back coatings provided on the light incident side surfaces of the photoactive elements of solar cells; sliding members such as diaphragms of diaphragm pumps and various packings; agricultural films, carrier films for fuel cells, and weather-resistant covers such as various roofing materials and side walls; interior materials used in the construction field, and coating materials for glasses such as non-combustible fire safety glasses; lining materials such as laminated steel plates used in the household electrical appliances field, etc. are included.

[0070] Among others, the molded article of the present invention can be suitably used as a piping member (for example, a pipe, a joint, a gasket, and a packing) or a tube for transferring a fluid in a semiconductor manufacturing apparatus. Further, the molded article of the present invention can also be suitably used as an electric wire coating material. As a specific usage mode, a coated electric wire including a core wire and a coating layer provided around the core wire and made of the molded article of the present invention can be mentioned. The coated electric wire including the coating layer made of the molded article of the present invention is excellent in electrical characteristics because the core wire is hardly corroded and there is almost no variation in the outer diameter, and is suitably used as a high-frequency transmission cable, a flat cable, a heat-resistant cable, and the like. Such a coated electric wire can be manufactured, for example, by melt-extrusion molding a copolymer or the present composition on the core wire to form a coating layer.

[0071] Moreover, the molded article of the present invention can also be suitably used as a member to be compressed. The member to be compressed is a member used in a state of being compression-deformed, and the size and shape of the member to be compressed are appropriately set according to the application. The shape of the member to be compressed may be, for example, annular. Further, the member to be compressed may have a shape such as a circle, an ellipse, or a square with rounded corners in a plan view, and may have a through hole in the central portion thereof. The member to be compressed can be used as a piping member for transferring a fluid. Further, the member to be compressed can be used as a member for constituting a non-aqueous electrolyte battery, and is particularly suitable as a member used in a state of being in contact with the non-aqueous electrolyte in the non-aqueous electrolyte battery. The member to be compressed can also be suitably used as a sealing member such as a sealing gasket and a sealing packing, and an insulating member such as an insulating gasket and an insulating packing. The sealing member is a member used to prevent leakage of a liquid or a gas, or intrusion of a liquid or a gas from the outside. The insulating member is a member used to insulate electricity. The member to be compressed may be a member used for both purposes of sealing and insulation.

Examples

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

[0073] [Measurement] [Composition of copolymer] The content (mol%) of unit A and unit B in each copolymer was determined by 19 converting the molar ratio calculated by 19F-NMR analysis.

[0074] [Number of functional groups N] Using the solid obtained in each example as a raw material, it was molded by a hot press at 330 °C to produce a film with a thickness of 0.30 to 0.35 mm. This film was scanned 40 times with a Fourier transform infrared spectrometer (FT-IR, "Spectrum One" manufactured by PerkinElmer) and analyzed to obtain an infrared absorption spectrum. Next, the fluorination treatment described below was performed on the solid obtained in each example for a long time to separately prepare each base pellet that was completely fluorinated and had no specific functional groups. In the same manner as above, a base film was obtained. Next, a difference spectrum was obtained between the infrared absorption spectrum of the film obtained by molding the solid of each example and the base spectrum of the base film. From the absorption peak of the specific functional group appearing in this difference spectrum, according to the above formula (A), the number of specific functional groups per 10 main chain carbons of the copolymer contained in each solid 6 was calculated as the total number of specific functional groups (number of functional groups N).

[0075] [Content of compound (3)] The solid obtained in each example was cryogenically pulverized using a cryogenic pulverizer "Freezer Mill 6775" (manufactured by SPEX) under the following conditions. When subjecting to cryogenic pulverization, 10% by mass of dibutylhydroxytoluene (BHT) was added to the solid based on the total mass of the solid in advance, and the obtained mixture was cryogenically pulverized to obtain a sample of the pulverized product. The conditions for freeze grinding were as follows: solid content: 3 g, BHT: 0.3 g, Run time: 5 mins, Rate: 15 cps, Cycle: 3. To 2.5 g of the obtained ground sample, 5 mL of methanol was added. The resulting mixture was subjected to ultrasonic treatment at 50 °C for 2 hours and centrifuged (5000 rpm, 5 minutes) to precipitate the copolymer contained in the ground sample, and the supernatant was collected as the extract.

[0076] LC-MS analysis was performed on each extract under the following conditions to measure and quantify the content of compound (3) contained in the extract. Specifically, first, a methanol standard solution of compound (3) at five levels with known concentrations in the range of 1 to 10000 ng / g was prepared. From the concentration of each standard solution and the integrated value of the peak area detected by LC-MS analysis, a straight line passing through the origin and represented by the following formula (A1) was derived by linear approximation to obtain the slope a. A = a × x (A1) In formula (A1), A represents the peak area of the detected compound (3), and x represents the concentration (ng / g) of compound (3) with respect to the total mass in the methanol standard solution.

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

[0078]

Table 2

[0079]

Table 3

[0080] Next, for the extract prepared by the above method from the solid matter obtained in each example, LC-MS analysis by the MRM method was performed under the above conditions using the above apparatus, and the peak area of the compound (3) with each carbon number was determined. Subsequently, the content of the compound (3) with each carbon number contained in the extract was calculated using the following formula (A2). XCm = ACm / a (A2) In formula (A2), XCm represents the content (ng / g) of the compound (3) with each carbon number in the extract, ACm represents the peak area of the compound (3) with each carbon number detected by LC-MS analysis of the extract, and a represents the slope a obtained by the above formula (A1). Note that the quantification limit in the above LC-MS analysis was 1 ng / g.

[0081] Next, using the following formula (A3), the content (ZCm) of the compound (3) with respect to the total mass of the solid matter obtained in each example was determined. ZCm = XCm × ρ1 × La / W1 (A3) In formula (A3), ZCm represents the content of the compound (3) with each carbon number contained in the solid matter, 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 matter contained in the extract (2.5 g in each example). The contents (ZCm) of the compound (3) with each carbon number obtained from formula (A3) were summed to determine the content (total content) of the compound (3) contained in the solid matter obtained in each example.

[0082] <mfr> For each solid obtained, using a melt indexer (manufactured by Technoseven Co., Ltd.), in accordance with ASTM D1238, under the conditions of a temperature of 372 °C and a load of 5 kg, the mass (g) of the solid flowing out from an orifice with a diameter of 2 mm and a length of 8 mm in 10 minutes was measured and taken as the MFR (g / 10 min).

[0083] [Evaluation Test] [Ozone Resistance] The solids produced in each example were compression-molded at 340 °C to produce a sheet with a thickness of 1 mm. The obtained sheets were cut into pieces of 10 mm × 20 mm size and used as samples for the ozone exposure test.

[0084] A test apparatus was prepared in which an ozone generator (trade name: SGX-A11MN (modified), manufactured by Sumitomo Seiki Co., Ltd.), a PFA container filled with ion-exchanged water, and a PFA cell containing the sample were connected in this order. Ozone gas (volume ratio of ozone / oxygen = 10 / 90) generated by the ozone generator was bubbled in ion-exchanged water to add water vapor to the ozone gas. The obtained wet ozone gas was passed through the PFA cell containing the sample at 0.7 liter / min to expose the sample to the wet ozone gas. In the ozone exposure test, the temperature was maintained at 40 °C and the humidity at 80% RH.

[0085] After 180 days from the start of the ozone exposure test, the sample was taken out and the surface of the sample was gently rinsed with ion-exchanged water. Then, the surface of the sample was photographed using a laser microscope, and the number of blisters with a major axis of 1 μm or more was counted. The major axis of the blister means the maximum diameter of the blister as viewed from the normal direction of the sample surface. Based on the following evaluation criteria, the ozone resistance of each solid was evaluated from the counted number of blisters.

[0086] [Ozone Resistance Evaluation Criteria] ○: The number of blisters is 10 pieces / mm 2 or less ×: The number of blisters is more than 10 pieces / mm 2 more than

[0087] [Example 1] 134 g of CF3CH2OCF2CF2H (AE-3000: product name, manufactured by AGC), 39.8 g of CF2=CFO(CF2)3F (PPVE), 36.1 g of methanol, 426.7 g of ultrapure water, and 142 g of TFE were added to a 1.2 L stainless steel reaction vessel, and the mixture was heated to 50 °C (polymerization temperature) in the reaction vessel while stirring with a stirring blade. 3 mL of heptafluorobutyryl peroxide (PFB) (0.06% by mass, AE-3000 solution) was added to the reaction vessel to initiate polymerization. Since the pressure in the reaction vessel decreased when polymerization was initiated, TFE was continuously pressure-fed so that the pressure was maintained at the same level as the pressure at the start of polymerization. 2 mL of PFB (0.06% by mass, AE-3000 solution) was added every 10 minutes after polymerization was initiated. When the pressure-fed amount of TFE reached 160 g, the polymerization reaction was terminated, the reaction vessel was cooled, and the remaining TFE was recovered.

[0088] The slurry was taken out 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 powdery solid X1 containing copolymer X1. 19 As a result of 19F-NMR analysis, the composition of copolymer X1 was unit A / PPVE unit = 98.5 / 1.5 mol%. The "PPVE unit" is a unit based on PPVE in each copolymer and is included in unit B1. In the analysis of the above copolymer X1, units other than the PPVE unit contained in unit B were not detected. The functional group number N of copolymer X1 determined according to the above measurement method was 500 or more per 10 main chain carbon atoms 6 atoms. Also, as a result of measurement according to the above measurement method, the bulk density of solid X1 was 0.33 g / mL, and the average particle diameter of solid X1 was 550 μm.

[0089] <Fluorination treatment> Next, solid X1 was fluorinated by the following method. A tray with solid X1 was placed in a box-type reaction oven, and the oven was sealed. After reducing the pressure inside the oven, an F2 / N2 mixed gas obtained by diluting F2 gas with N2 gas to a concentration of 20% by volume was introduced into the oven. The pressure inside the oven was set to 1 atm (1 atmosphere), and the temperature inside the oven was set to 230 °C. One hour after the start of the introduction of the F2 / N2 mixed gas, the pressure inside the oven was reduced, and the F2 / N2 mixed gas was introduced again, and the reaction was carried out at 230 °C for 1 hour. After the reaction was completed, heating was stopped, and N2 gas was introduced into the oven to sufficiently replace the F2 / N2 mixed gas inside the oven with N2 gas, and the fluorination treatment was terminated.

[0090] <Heat treatment> A mesh tray covered with the fluorinated solid was placed in a box-type reaction oven, and the oven was sealed. The pressure inside the oven was reduced, and the solid placed on the mesh tray was heated at 180 °C for 5 hours under a pressure of 1.5 kPa. After heating, the solid was cooled, and N2 gas was introduced into the oven to replace the gas inside the oven with N2 gas. The pressure inside the oven was set to 1 atm, and then the oven was opened. Through the above fluorination treatment and heat treatment, a powdery solid Y1 containing copolymer Y1 was obtained.

[0091] 19 As a result of 19F-NMR analysis, the composition of copolymer Y1 contained in solid Y1 was the same as the composition of copolymer X1. Also, as a result of measurement by the above method, the number of functional groups N of copolymer Y1 was less than 50 per 10 main-chain carbon atoms 6 and the content of compound (3) contained in solid Y1 was less than 25 mass ppb with respect to the total mass of solid Y1. The bulk density and average particle diameter of solid Y1 were the same as those of solid X1, respectively.

[0092] [Example 2] In a 1.2 L stainless steel reaction vessel, CF3CH2OCF2CF2H (AE - 3000: product name, manufactured by AGC) (80.5 g), CF2 = CFCF2OCF2CF2CF3 (79.6 g), 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 reaction vessel reached 1.4 MPaG (gauge pressure), 6 mL of tert - butyl peroxy pivalate (0.5 mass%, AE - 3000 solution) was added to initiate the polymerization. When the polymerization started, the pressure inside the reaction vessel decreased, so TFE was continuously added to keep the pressure equal to the pressure at the start of polymerization. When the added amount of TFE reached 160 g, the polymerization reaction was terminated, the reaction vessel was cooled, and the remaining TFE was recovered.

[0093] The slurry was taken out from the reaction vessel, and the polymerization solvent was recovered with an evaporator. The residue of the obtained slurry was heated at 150 °C for 12 hours to obtain a powdery solid X2 containing copolymer X2. 19 As a result of 19F - NMR analysis, the composition of copolymer X2 was unit A / PFAE unit = 98.5 / 1.5 mol%. The "PFAE unit" is a unit based on PFAE of each copolymer and is included in unit B2. In the analysis of the above copolymer X2, units other than the PFAE unit contained in unit B were not detected. The functional group number N of copolymer X2 determined according to the above measurement method was 500 or more per 10 main - chain carbon atoms 6 atoms. Also, the bulk density of solid X2 was 0.33 g / mL, and the average particle diameter of solid X2 was 570 μm.

[0094] Except for using solid X2 instead of solid X1, fluorination treatment and heat treatment were carried out on solid X2 in the same manner as in Example 1 to obtain a powdery solid Y2 containing copolymer Y2. 19 As a result of 19F - NMR analysis, the composition of copolymer Y2 contained in solid Y2 was the same as the composition of copolymer X2. Also, as a result of measurement by the above method, the functional group number N of copolymer Y2 was 10 main - chain carbon atoms 6 Less than 50 per unit, and the content of compound (3) contained in solid Y2 was less than 25 mass ppb with respect to the total mass of solid Y2. The bulk density and average particle diameter of solid Y2 were the same as those of solid X2, respectively.

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

[0096] 19 As a result of 19F-NMR analysis, the composition and the number of functional groups N of copolymer X1 contained in solid X3 were the same as those of copolymer X1 contained in solid X1. Also, 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 method of fluorination treatment described in Example 1 to obtain a pellet-shaped solid Y3 containing copolymer Y3. 19 As a result of 19F-NMR analysis, the composition of copolymer Y3 was the same as that of copolymer X1 contained in solid X3. Also, as a result of measurement by the above method, the number of functional groups N of copolymer Y3 was less than 50 per 10 main-chain carbon atoms 6 and the content of compound (3) contained in solid Y3 was 5000 mass ppb with respect to the total mass of solid Y3.

[0098] [Example 4] Except for using the pellet-shaped solid X3 produced in Example 3 instead of the solid X1, fluorination treatment and heat treatment were performed on the solid X3 in the same manner as in Example 1 to obtain a pellet-shaped solid Y4 containing the copolymer Y4. 19 As a result of 19F-NMR analysis, the composition of the copolymer Y4 was the same as that of the copolymer X1 contained in the solid X3. Further, as a result of measurement by the above method, the functional group number N of the copolymer Y4 was less than 50 per 10 main chain carbon atoms, and the content of the compound (3) contained in the solid Y4 was 3000 mass ppb with respect to the total mass of the solid Y4. 6

[0099] [Example 5] According to the method described in Example 1, a powdery solid Y1 containing the copolymer Y1 was obtained. Next, according to the method of pelletizing the solid X1 in Example 3, the obtained solid Y1 was pelletized using an extrusion kneader. Thereby, a pellet-shaped solid Y5 containing the copolymer Y5 was produced. The shape of the solid Y5 was a cylindrical shape with a length of 5 mm or less and a ratio of length to diameter (length / diameter) of 0.5 or more and less than 1.5. Both the composition and the functional group number N of the copolymer Y5 contained in the solid Y5 were the same as those of the copolymer Y1 contained in the solid Y1. Also, the content of the compound (3) contained in the solid Y5 was the same as the content of the compound (3) contained in the solid Y1.

[0100] [Example 6] A powdery solid Y6 containing the copolymer Y6 was obtained in the same manner as in Example 1, except that only fluorination treatment was performed on the obtained powdery solid X1 and heat treatment was not performed. 19 As a result of 19F-NMR analysis, the composition of the copolymer Y6 contained in the solid Y6 was the same as that of the copolymer X1. Further, as a result of measurement by the above method, the functional group number N of the copolymer Y6 was 10 per main chain carbon atom 6 The amount of compound (3) contained in solid matter Y6 was 5,500 ppb by mass relative to the total mass of solid matter Y6. The bulk density and average particle size of solid material Y6 were the same as those of solid material X1.

[0101] The following table shows the copolymer composition, solid properties, and evaluation results of each example. The column "Number of functional groups N" indicates the total number of specific functional groups in the copolymer X contained in the solid X or the copolymer Y contained in the solid Y. For example, the notation "500≦" in the "Number of functional groups N" column of "Copolymer X" in Example 1 indicates that the copolymer X1 has 10 main chain carbon atoms. 6 The notation "<50" in the "Number of functional groups N" column for "Copolymer Y" means that copolymer Y1 has 10 main chain carbon atoms. 6 This means that the total number of specific functional groups per unit was less than 50. The columns "Unit A (mol %)", "Unit B1 (mol %)" and "Unit B2 (mol %)" indicate the content of unit A (unit: mol %), the content of unit B1 (unit: mol %) and the content of unit B2 (unit: mol %), respectively, relative to the total units contained in the copolymer. The column "Compound (3) (mass ppb)" for "Solid Y" indicates the content of compound (3) (mass ppb) relative to the total mass of solid Y.

[0102] In each example, the contents of units A, units B1 and units B2 of copolymer X contained in solid material X before the fluorination treatment were the same as the contents of units A, units B1 and units B2 of copolymer Y contained in solid material Y after the fluorination treatment.

[0103] [Table 4]

[0104] As shown in the above table, a powder or pellet-like solid material containing a copolymer containing units A and B, and the number of functional groups N is 10 6 By using the solid matter of the present invention having less than 150 per piece and substantially not containing the compound (3), it was confirmed that a molded body excellent in ozone resistance, in which blisters due to ozone hardly occur, can be formed (Examples 1, 2 and 5).< / mfr>

Claims

1. A powdered or pellet-like solid material comprising 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) and a monomer represented by formula (2), -CF = CF ２ , -CF ２ H, -COF, -COOH, -COOCH ３ , -CONH ２ and -CH ２ The total number of OH functional groups is 10 or less than 10 carbon atoms in the main chain of the copolymer. ６ There are less than 150 pieces per piece, A solid material, characterized by being substantially free of a 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 material according to claim 1, wherein the content of the unit A is 95.0 to 99.5 mol % based on the total units of the copolymer.

3. 2. The solid material according to claim 1, wherein the content of the unit B is 0.5 to 5.0 mol % based on the total units of the copolymer.

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

5. 2. The solid of claim 1, wherein said 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).

6. A molded product obtained by molding the solid material according to any one of claims 1 to 5.

7. A powdery solid material containing a copolymer including 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) and a monomer represented by formula (2) is fluorinated, The fluorination-treated powdery solid is heated at 100 to 250° C. for 1 hour or more to obtain a copolymer containing the unit A and the unit B, in which the total number of functional groups of —CF═CF 2 , —CF 2 H, —COF, —COOH, —COOCH 3 , —CONH 2 and —CH 2 OH is equal to or greater than 10 carbon atoms in the main chain of the copolymer. ６ A method for producing a solid material, comprising obtaining a powdered or pelletized solid material containing a copolymer having less than 150 units per pellet. 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 formula (1) and formula (2), n represents 1 to 9.

8. The powdered solid material to be subjected to the fluorination treatment has a bulk density of 0.10 to 0.70 g / cm ３ The method for producing a solid material according to claim 7,

9. The method for producing a solid material according to claim 7 or 8, wherein the powdered solid material that has been fluorination-treated is heated under a reduced pressure of 2.0 kPa or less.

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