Method for manufacturing solid composition, solid composition, crosslinked rubber article

Abstract

Provided is a method for producing a solid composition that can produce a solid composition that is substantially free of an emulsifier and has excellent crosslinking speed. A method for producing a solid composition, wherein, in an aqueous dispersion that is substantially free of a water-soluble emulsifier and contains a first fluorine-containing polymer and an aqueous medium, a monomer containing TFE and PAVE is polymerized, the resulting aqueous dispersion containing a second fluorine-containing polymer is subjected to a stirring treatment, and a solid obtained after the stirring treatment is recovered to obtain a solid composition, the aforementioned first fluorine-containing polymer contains TFE units and PAVE units, in the first fluorine-containing polymer, the PAVE units are 5 to 80 mol% relative to the total of the TFE units and the PAVE units, in the second fluorine-containing polymer, the PAVE units are 15 to 95 mol% relative to the total of the TFE units and the PAVE units, and the content of the first fluorine-containing polymer is 0.01 to 4.0 mass% relative to the total mass of the aqueous dispersion before the polymerization of the monomer is started.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a solid composition, a solid composition, and a cross-linked rubber article. Background Technology

[0002] Crosslinked rubber articles, obtained by crosslinking a composition containing fluoropolymers, are used in various industrial fields due to their excellent heat resistance, chemical resistance, flame retardancy, and weather resistance.

[0003] As a method for manufacturing such fluoropolymers, one example is the method of emulsion polymerization of fluoromonomers in an aqueous medium using an emulsifier (see Patent Document 1).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2022 / 052498 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] The method for manufacturing fluoropolymers in Patent Document 1 uses an emulsifier during polymerization. However, there are concerns that the presence of emulsifier residues in cross-linked rubber articles manufactured using a composition containing fluoropolymers could lead to adverse effects such as environmental pollution. Recently, there have been calls to reduce the amount of emulsifier used.

[0009] In addition, from the perspective of manufacturing efficiency, a fast cross-linking speed is required when manufacturing cross-linked rubber articles.

[0010] That is, there is a recent demand for fluorinated solid compositions that are substantially free of emulsifiers and have excellent crosslinking speed.

[0011] The present invention was made in view of the above-mentioned problems, and its objective is to provide a method for manufacturing a solid composition capable of producing a solid composition that is substantially free of emulsifiers and has an excellent crosslinking rate. Furthermore, another objective of the present invention is to provide the aforementioned solid composition.

[0012] Solution for solving the problem

[0013] The inventors conducted in-depth research on the above-mentioned issues and discovered that by polymerizing monomers in an aqueous dispersion containing a specified first fluoropolymer that is substantially free of emulsifiers and then performing stirring treatment to recover the solid composition, a solid composition can be obtained without the need for emulsifiers and components that reduce the crosslinking rate, thus completing the present invention.

[0014] That is, the inventors have discovered that the above-mentioned problems can be solved by the following configuration.

[0015] [1] A method for manufacturing a solid composition, wherein a monomer comprising tetrafluoroethylene and a perfluorinated (alkyl vinyl ether) is polymerized in an aqueous dispersion comprising a first fluoropolymer and an aqueous medium, which is substantially free of a water-soluble emulsifier, the aqueous dispersion comprising a second fluoropolymer is subjected to stirring treatment, and the solid obtained after the stirring treatment is recovered to obtain a solid composition.

[0016] The aforementioned first fluoropolymer comprises tetrafluoroethylene-based units and perfluoro(alkyl vinyl ether)-based units.

[0017] In the aforementioned first fluoropolymer, the percentage of the perfluoro(alkyl vinyl ether)-based units is 5 to 80 mol%, relative to the total of the tetrafluoroethylene-based units and the perfluoro(alkyl vinyl ether)-based units.

[0018] In the aforementioned second fluoropolymer, the percentage of the perfluoro(alkyl vinyl ether)-based units is 15-95 mol%, relative to the total of the tetrafluoroethylene-based units and the perfluoro(alkyl vinyl ether)-based units.

[0019] Before the polymerization of the monomers begins, the content of the first fluoropolymer is 0.01 to 4.0% of the total mass of the aqueous dispersion.

[0020] [2] According to the method for manufacturing the solid composition described in [1], wherein the storage modulus of the solid composition at 100°C is 300 kPa or more.

[0021] [3] The method for manufacturing a solid composition according to [1] or [2], wherein the solid composition is free of emulsifier;

[0022] Alternatively, if the solid composition contains the emulsifier, the total content of the emulsifier relative to the total mass of the solid composition is 500 ppb or less.

[0023] [4] The method for manufacturing a solid composition according to any one of [1] to [3], wherein the total content of metals in the solid composition is less than 20 ppm by mass relative to the total mass of the solid composition.

[0024] [5] The method for manufacturing a solid composition according to any one of [1] to [4], wherein, in the second fluoropolymer, the tetrafluoroethylene-based unit is 35 to 80 mol, relative to all units; and the perfluoro (alkyl vinyl ether)-based unit is 20 to 60 mol.

[0025] [6] The method for manufacturing a solid composition according to any one of [1] to [5], wherein the second fluoropolymer comprises at least one selected from the group consisting of polymerizable unsaturated bonds, chlorine atoms, bromine atoms, iodine atoms and nitrile groups.

[0026] [7] The method for manufacturing the solid composition according to any one of [1] to [6] includes a step of cleaning the solid composition.

[0027] [8] A solid composition comprising: a fluoropolymer containing tetrafluoroethylene-based units and perfluoro(alkyl vinyl ether)-based units,

[0028] The aforementioned solid composition is substantially free of emulsifiers and satisfies requirement X.

[0029] Requirement X: In the mixture obtained by mixing the above solid composition and water with pH 6 in such a way that the mass of the water is 5 times that of the mass of the above solid composition, the pH of the mixture at 23°C is 4 or higher 24 hours after the above mixing. [9]

[0031] The solid composition according to [8] is substantially free of coagulants.

[10]

[0033] A cross-linked rubber article formed by cross-linking the solid composition described in [8] or [9].

[0034] The effects of the invention

[0035] According to the present invention, a method for manufacturing a solid composition capable of producing a solid composition that is substantially free of emulsifiers and exhibits excellent crosslinking speed can be provided. Furthermore, according to the present invention, the aforementioned solid composition and a crosslinked rubber article formed by crosslinking the solid composition can also be provided. Detailed Implementation

[0036] The meanings of the terms used in this invention are as follows.

[0037] The range of values ​​represented by "~" refers to the range of values ​​recorded before and after "~" as the lower and upper limits.

[0038] In the numerical ranges described in this specification, the upper or lower limit value recorded in a certain numerical range can be replaced with the upper or lower limit value of other numerical ranges described in different periods. Additionally, the upper or lower limit value recorded in a certain numerical range described in this specification can also be replaced with the value shown in the embodiment.

[0039] In this specification, each component may be used alone with one equivalent substance, or with two or more substances used in combination. When two or more substances are used in combination for each component, unless otherwise specified, the content of that component refers to the total content of the substances used in combination.

[0040] In this specification, a combination of two or more preferred methods is a more preferred method.

[0041] "Unit" refers to the atomic group directly formed by the polymerization of monomers, originating from one molecule of the aforementioned monomer, and the atomic group obtained by chemically transforming a portion of the aforementioned atomic group. "Monomer-based unit" is also referred to as "unit" below.

[0042] The content (mass % or mole %) of each unit relative to all units contained in the polymer is determined by analyzing the polymer using solid-state nuclear magnetic resonance spectroscopy (NMR). Generally, the content of each unit calculated from the amount of each monomer fed is roughly consistent with the actual content of each unit.

[0043] [Method for manufacturing solid compositions]

[0044] The method for manufacturing the solid composition of the present invention (hereinafter also referred to as "the manufacturing method") comprises an aqueous dispersion (hereinafter also referred to as "the first aqueous dispersion") that is substantially free of water-soluble emulsifier and contains a first fluoropolymer and an aqueous medium.

[0045] The monomers containing TFE and PAVE are polymerized, and the resulting aqueous dispersion containing a second fluoropolymer (hereinafter also referred to as "second aqueous dispersion") is stirred. The solids obtained after the stirring are recovered to obtain a solid composition. The aforementioned first fluoropolymer contains units based on tetrafluoroethylene (hereinafter also referred to as "TFE") and units based on perfluoro(alkyl vinyl ether) (hereinafter also referred to as "PAVE").

[0046] In the aforementioned first fluoropolymer, the PAVE-based units comprise 5 to 80 mol% relative to the total of the TFE-based units and the PAVE-based units.

[0047] In the second fluoropolymer described above, the PAVE-based units comprise 15 to 95 mol% relative to the total of the TFE-based units and the PAVE-based units described above.

[0048] Before the polymerization of the monomers begins, the content of the first fluoropolymer is 0.01 to 4.0% of the total mass of the aqueous dispersion.

[0049] According to this manufacturing method, a solid composition that is substantially emulsifier-free and exhibits excellent crosslinking speed can be produced. The detailed rationale is not yet clear, but by polymerizing in a first aqueous dispersion containing a predetermined amount of a first fluoropolymer, which functions as the polymerization site, the monomer can polymerize without the use of an emulsifier, thus obtaining a substantially emulsifier-free solid composition. When an emulsifier is used during polymerization, a coagulant such as an acid is typically required to recover the solids from the polymerized aqueous dispersion. If such a coagulant remains in the solid composition, the crosslinking reaction is hindered, and the crosslinking speed decreases. As described above, this manufacturing method involves polymerization in a first aqueous dispersion that is substantially emulsifier-free, and therefore, a solid composition can be obtained through stirring. It is presumed that the solid composition obtained in this way does not contain components that hinder crosslinking, and therefore exhibits excellent crosslinking speed.

[0050] In this specification, the process of polymerizing monomers containing TFE and PAVE in a first aqueous dispersion to obtain a second aqueous dispersion containing a second fluoropolymer is also referred to as "Process 1," and the process of stirring the second aqueous dispersion to recover solids and obtain a solid composition is also referred to as "Process 2." The monomers containing TFE and PAVE used in the process of obtaining the second aqueous dispersion containing the second fluoropolymer are also referred to as "specific monomers."

[0051] The following is a description of each process.

[0052] <Process 1>

[0053] In step 1 of this manufacturing method, polymerization is carried out in a first aqueous dispersion containing a first fluoropolymer and an aqueous medium that is substantially free of water-soluble emulsifier.

[0054] (First aqueous dispersion)

[0055] -Emulsifier-

[0056] The first aqueous dispersion does not use water-soluble emulsifiers and is essentially free of water-soluble emulsifiers.

[0057] "Substantially free of water-soluble emulsifiers" means that the content of water-soluble emulsifiers in the first aqueous dispersion is 10 ppm by mass or less relative to the total mass of the first aqueous dispersion, preferably 100 ppb by mass or less, and more preferably 50 ppb by mass or less. Furthermore, it is also preferably below the quantitative limit of the determination method in the examples. One ppb by mass is an example of a lower limit.

[0058] The content of water-soluble emulsifiers can be determined using liquid chromatography-mass spectrometry. Specifically, the determination method described in paragraphs 0721-0732 of International Publication No. 2018 / 181904, and the determination method shown in the preferred embodiment, can be cited.

[0059] Water-soluble emulsifiers are those with a solubility of more than 100 mg per 1000 g of water at 25°C.

[0060] Examples of water-soluble emulsifiers include those containing fluorine atoms and those without fluorine atoms. It should be noted that the first and second fluorinated polymers described later are not emulsifiers.

[0061] Water-soluble emulsifiers can be either ionic or nonionic.

[0062] Anionic fluorinated emulsifiers can be cited as examples of emulsifiers containing fluorine atoms.

[0063] Examples of anionic fluorinated emulsifiers include emulsifiers containing fluorine atoms in which the total number of carbon atoms in the portion other than the anionic group is 20 or less, and emulsifiers containing fluorine in which the molecular weight of the anionic portion is 800 or less.

[0064] Emulsifiers without fluorine atoms do not contain fluorine atoms but have hydrocarbon groups such as alkyl groups. The hydrogen atoms in the hydrocarbon groups of emulsifiers without fluorine atoms can also be replaced by halogen atoms other than fluorine atoms.

[0065] Examples of emulsifiers that do not have fluorine atoms include ionic hydrocarbon emulsifiers and nonionic hydrocarbon emulsifiers.

[0066] Anionic hydrocarbon emulsifiers can be cited as examples of ionic hydrocarbon emulsifiers.

[0067] Anionic hydrocarbon emulsifiers refer to hydrocarbon emulsifiers that have negatively charged hydrophilic parts such as carboxylic acid groups, sulfonic acid groups, sulfuric acid groups, phosphonic acid groups and phosphate groups, and hydrocarbon parts such as alkyl groups that are hydrophobic.

[0068] Examples of anionic hydrocarbon emulsifiers include: highly branched C10 tertiary carboxylic acids provided by Resolution Performance Products under the trademark Versatic 10; sodium linear alkyl polyether sulfonate and sodium dodecyl sulfate provided by BASF under the trademark Avanel S series; and the sulfosuccinate emulsifier Lankropol K8300 available from AkzoNobelSurfaceChemistry LLC.

[0069] Nonionic hydrocarbon emulsifiers are emulsifiers that do not dissociate into ions in water and exhibit surface activity, having alkyl or other hydrocarbon groups as hydrophobic parts.

[0070] Examples of water-soluble functional groups, such as polyoxyethylene chains obtained from the polymerization of ethylene oxide, can be cited as the hydrophilic portion of nonionic hydrocarbon emulsifiers. Examples of nonionic hydrocarbon emulsifiers include polyoxyethylene block copolymers, such as block copolymers containing polyoxyethylene and polyoxypropylene.

[0071] As a nonionic hydrocarbon emulsifier, the emulsifier described in paragraphs

[0043] to

[0052] of Japanese Patent Publication No. 2016-537499 can be cited as an example.

[0072] Emulsifiers having fluorine atoms and emulsifiers not having fluorine atoms may contain silicon atoms. Examples of silicon-containing emulsifiers include siloxane emulsifiers. Examples of siloxane emulsifiers include those described in U.S. Patent No. 6,841,616 (Wille et al.) and U.S. Patent No. 7,977,438 (Brothers et al.).

[0073] Emulsifiers having fluorine atoms and those not having fluorine atoms can be polymeric emulsifiers. Examples of polymeric emulsifiers include water-soluble polymers with hydrophilic groups on their side chains. Examples of such polymeric emulsifiers include polymers comprising units based on compounds having sites capable of reacting in polymerization and hydrophilic groups. Furthermore, examples include polymers obtained by post-treatment such as hydrolysis of polymers based on compounds having groups that, even if not hydrophilic during polymerization, can become hydrophilic.

[0074] The first aqueous dispersion preferably does not contain any of the emulsifiers represented by formulas (S1) to (S4). When an emulsifier is not used when manufacturing the first fluoropolymer contained in the first aqueous dispersion, the amount of compounds represented by any of formulas (S1) to (S4) can be suppressed, and the adjustment of the content of these compounds becomes easy.

[0075] H-(CF2) n1 -COOM (S1)

[0076] F-(CF2) n1 -COOM (S2)

[0077] H-(CF2) n2 -SO3M (S3)

[0078] F-(CF2) n2 -SO3M (S4)

[0079] In equations (S1) to (S4),

[0080] n1 is an integer between 3 and 19.

[0081] n² is an integer between 4 and 20.

[0082] M can be a hydrogen atom, Na, K, or NH4 independently.

[0083] -First Fluoropolymer-

[0084] The first fluoropolymer comprises TFE-based units and PAVE-based units.

[0085] It is speculated that the first fluoropolymer adsorbs and introduces the specific monomer into the hydrophobic portion during the polymerization of the specific monomer (described later), making the specific monomer soluble even in the absence of an emulsifier in the first aqueous dispersion, thus facilitating the polymerization of the specific monomer. Furthermore, it is speculated that the first fluoropolymer also contributes to the dispersion stabilization in the first aqueous dispersion.

[0086] From the perspective of excellent polymerization reactivity when manufacturing the first fluoropolymer and the ability to manufacture the second fluoropolymer more efficiently, PAVE prefers the monomer shown in formula (1).

[0087] CF2 = CF - OR f1 (1)

[0088] In equation (1), R f1 Represents perfluoroalkyl groups with 1 to 10 carbon atoms. From the perspective of superior polymerization reactivity, R... f1 The number of carbon atoms is preferably 1 to 8, more preferably 1 to 6, even more preferably 1 to 5, and particularly preferably 1 to 3.

[0089] Perfluoroalkyl groups can be linear or branched.

[0090] Specific examples of PAVE include perfluoro(methyl vinyl ether) (hereinafter also referred to as "PMVE"), perfluoro(ethyl vinyl ether) and perfluoro(propyl vinyl ether) (hereinafter also referred to as "PPVE"). From the perspective of being able to manufacture the second fluoropolymer more efficiently, PMVE or PPVE is preferred, and PMVE is more preferred.

[0091] In the first fluoropolymer, the TFE unit is 20 to 95 mol% relative to the total of the TFE-based unit (also called "TFE unit") and the PAVE-based unit (also called "PAVE unit"), preferably 40 to 85 mol%, more preferably 50 to 75 mol%, and even more preferably 60 to 70 mol%, from the viewpoint of being able to manufacture the second fluoropolymer more efficiently.

[0092] In the first fluoropolymer, the PAVE unit comprises 5 to 80 mol% relative to the total of TFE and PAVE units, preferably 15 to 60 mol%, more preferably 25 to 55 mol%, and even more preferably 30 to 40 mol%, from the perspective of enabling more efficient production of the second fluoropolymer. The preferred amount is the same when PMVE or PPVE units are used as PAVE units.

[0093] In the first fluoropolymer, the total content of TFE units and PAVE units is preferably 99.0 to 100.0 mol% relative to all units of the first fluoropolymer, more preferably 99.5 to 100.0 mol%, and even more preferably 99.9 to 100.0 mol%.

[0094] The first fluoropolymer may contain units based on monomers other than TFE and PAVE, and from the perspective of being able to manufacture the second fluoropolymer more efficiently, it is also preferable that it does not contain units based on other monomers.

[0095] Essentially, "not containing units based on other monomers" means that the content of units based on other monomers is less than 0.01 mol% relative to all units of the first fluoropolymer, preferably 0 mol%.

[0096] Before starting the polymerization of a specific monomer, the content of the first fluoropolymer is 0.01 to 4.0% by mass relative to the total mass of the first aqueous dispersion, preferably 0.01 to 1.0% by mass, and more preferably 0.01 to 0.8% by mass, from the viewpoint of being able to manufacture the second fluoropolymer more efficiently.

[0097] It should be noted that, in this specification, "before starting the polymerization of a specific monomer" refers to the moment just before polymerization begins. Here, "the moment of starting polymerization" can be exemplified by the moment when the specific monomer (or, in the case of using a polymerization initiator, both polymerization initiator and specific monomer) coexists in the reactor after the reactor has been brought to a temperature above the polymerization temperature, or the moment when the reactor temperature has been brought to a temperature above the polymerization temperature after the specific monomer (or, in the case of using a polymerization initiator, both polymerization initiator and specific monomer) has coexisted in the reactor.

[0098] The content (solid component concentration) of the first fluoropolymer in the first aqueous dispersion can be determined, for example, by the following methods.

[0099] After heating 2.0g of the first aqueous dispersion at 170℃ for 20 minutes, the mass of the residue was weighed, and the concentration of the solid component was calculated using the following formula.

[0100] "Solid component concentration (mass %) = 100 × mass of heating residue of the first aqueous dispersion (g) / mass of the first aqueous dispersion (2.0g)"

[0101] As a method for manufacturing the first fluoropolymer, a preferred method is to polymerize a monomer containing TFE and PAVE in an aqueous medium in the presence of a polymerization initiator. This yields a first fluoropolymer dispersed in particulate form in an aqueous medium.

[0102] The aqueous medium containing the particles of the first fluoropolymer obtained in this way can be used directly as the first aqueous dispersion. Alternatively, solvent displacement can be performed to disperse the first fluoropolymer in other aqueous media and use them as the first aqueous dispersion.

[0103] Water-soluble polymerization initiators are preferred as polymerization initiators used in the polymerization of the first fluoropolymer. Among water-soluble polymerization initiators, persulfate-based initiators such as ammonium persulfate, sodium persulfate, and potassium persulfate, or organic polymerization initiators such as disuccinate peroxide and azobisisobutylamidine dihydrochloride are more preferred, persulfate-based initiators are even more preferred, and ammonium persulfate is particularly preferred among persulfate-based initiators.

[0104] Examples of aqueous media used in the manufacture of the first fluoropolymer include water and mixtures of water and water-soluble organic solvents. Specific examples of water-soluble organic solvents include tert-butanol, propylene glycol, dipropylene glycol, dipropylene glycol monomethyl ether, and tripropylene glycol.

[0105] In the manufacture of the first fluoropolymer, it is preferable that it is substantially free of emulsifiers. Emulsifiers (the types of emulsifiers and the definition of substantially free, etc.) are as described above.

[0106] The first aqueous dispersion containing the first fluoropolymer is preferably used for the polymerization of a specific monomer after undergoing a purification treatment that reduces or deactivates the polymerization initiator and its decomposition products. By removing the polymerization initiator and its decomposition products contained in the first aqueous dispersion containing the first fluoropolymer through purification treatment, a solid composition with the desired physical properties can be readily obtained.

[0107] Methods for purification include, for example, heat treatment and passing liquid through an ion exchange resin (preferably anion exchange resin).

[0108] The purification process can be performed multiple times.

[0109] From the viewpoint of removal efficiency, the total exchange capacity of the anion exchange resin is preferably 0.1 eq / L resin (L-Resin) or more, more preferably 0.3 eq / L-Resin or more, even more preferably 0.5 eq / L-Resin or more, and particularly preferably 0.7 eq / L-Resin or more. The total exchange capacity of the anion exchange resin can be 20 eq / L-Resin or less.

[0110] The anion exchange resin is preferably spherical. The average particle size of the anion exchange resin is preferably 0.1–5 mm, more preferably 0.2–2 mm, and even more preferably 0.3–1.5 mm. If the average particle size of the anion exchange resin is within the above range, it is less prone to clogging during filling. The average particle size of the anion exchange resin is determined by sieving. Specifically, firstly, the anion exchange resin is placed in a sieving shaker, and the particle size distribution is determined by sieving. Then, the diameter of the sieve opening corresponding to 50% by mass of the residual component is determined and used as the average particle size.

[0111] Anion exchange resins can be gel-type or macroporous. The resin's framework structure can be acrylic-based or styrene-based. Furthermore, the functional groups in the anion exchange resin can be strongly basic or weakly basic; from the viewpoint of impurity adsorption efficiency, strongly basic groups are preferred. The counter anion of the anion exchange resin can be chloride ions or hydroxide ions; from the perspective of further reducing the impurity concentration in the aqueous dispersion, hydroxide ions are preferred.

[0112] -Aqueous medium-

[0113] As a specific example of the aqueous medium contained in the first aqueous dispersion, the aqueous medium used in the manufacture of the aforementioned first fluoropolymer can be cited.

[0114] Before starting the polymerization of a specific monomer, the content of the aqueous medium relative to the total mass of the first aqueous dispersion is preferably 60 to 99.9% by mass, more preferably 96 to 99.9% by mass, and even more preferably 98 to 99.9% by mass.

[0115] -Other ingredients-

[0116] The first aqueous dispersion may contain components other than the first fluoropolymer and the aqueous medium.

[0117] Specific examples of the other components mentioned above include reducing agents, pH adjusters, and chain transfer agents, which will be discussed later.

[0118] Specific examples of pH adjusters include inorganic salts and ammonia. Specific examples of inorganic salts include phosphates such as disodium hydrogen phosphate and sodium dihydrogen phosphate, and carbonates such as sodium bicarbonate and sodium carbonate. More preferred specific examples of phosphates include disodium hydrogen phosphate dihydrate and disodium hydrogen phosphate dodecahydrate.

[0119] When the first aqueous dispersion contains a pH adjuster, the content of the pH adjuster is preferably 0.004 to 3.0 parts by mass relative to 100 parts by mass of the aqueous medium.

[0120] (Specific monomer)

[0121] The specific monomer is a monomer containing TFE and PAVE. The preferred manner of using TFE and PAVE as the specific monomer is the same as that of using TFE and PAVE in the first fluoropolymer described above.

[0122] The combined amount of TFE and PAVE is preferably 80 to 100 mol% relative to the amount of a specific monomer, more preferably 90 to 100 mol%, and even more preferably 95 to 100 mol%.

[0123] A particular monomer may contain monomers other than TFE and PAVE (hereinafter also referred to as "other monomers").

[0124] Specific examples of other monomers include monomers having two or more polymerizable unsaturated bonds (hereinafter also referred to as "BO"), and monomers having at least one atom selected from the group consisting of chlorine, bromine, and iodine atoms (hereinafter also referred to as "R"). Hal Monomers with nitrile groups (hereinafter also referred to as "R") CN ), and the compound shown in formula (6) described later (hereinafter also referred to as "POAVE").

[0125] BO is a monomer with two or more polymerizable unsaturated bonds.

[0126] Examples of polymerizable unsaturated bonds include carbon-carbon double bonds (C=C) and carbon-carbon triple bonds (C≡C).

[0127] The number of polymerizable unsaturated bonds in BO is preferably 2 to 6, more preferably 2 or 3, and even more preferably 2, from the perspective of better polymerization reactivity.

[0128] From the perspective that cross-linked rubber articles have less compression set at high temperatures, BO preferably contains fluorine atoms.

[0129] From the perspective of superior release properties of cross-linked rubber articles, BO is preferably the monomer shown in formula (2).

[0130] (CR 21 R 22 =CR 23 -) a1 R 24 (2)

[0131] In equation (2), R 21 R 22 and R 23 Each of these elements independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group; a1 represents an integer from 2 to 6; R 24This refers to a perfluoroalkyl group with 1 to 10 carbon atoms in the α1 valence, or a group with an ether-like oxygen atom at the end of a perfluoroalkyl group with 1 to 10 carbon atoms in the α1 valence or between carbon-carbon bonds. Multiple R 21 Multiple R 22 and multiple R 23 Each can be the same as or different from the others, but it is preferred that they are the same as each other.

[0132] a1 is preferably 2 or 3, and particularly preferably 2.

[0133] From the perspective of BO's superior polymerization reactivity, R is preferred. 21 R 22 and R 23 It is a fluorine atom or a hydrogen atom, more preferably R 21 R 22 and R 23 From the perspective of superior mold release properties of cross-linked rubber articles, R is particularly preferred, consisting entirely of fluorine atoms or entirely of hydrogen atoms. 21 R 22 and R 23 It consists entirely of fluorine atoms.

[0134] R 24 It can be any of the following: linear, branched, and cyclic, preferably linear or branched, and particularly preferably linear. R 24 The number of carbon atoms is preferably 2 to 8, more preferably 3 to 7, even more preferably 3 to 6, and particularly preferably 3 to 5.

[0135] R 24 The material can be selected from those with ether-like oxygen atoms, and those with ether-like oxygen atoms are preferred from the perspective of better crosslinking reactivity and rubber properties.

[0136] R 24 The number of ether-containing oxygen atoms is preferably 1 to 6, more preferably 1 to 3, and particularly preferably 1 or 2. R 24 The ether oxygen atom in R is preferably present in R 24 The end of.

[0137] Among the monomers shown in Equation (2), specific examples of preferred monomers include the monomers shown in Equation (3) and Equation (4).

[0138] (CF2=CF-)2R 31 (3)

[0139] In equation (3), R 31 It refers to a perfluorocarbon group with 1 to 10 carbon atoms in a divalent state, or a group having an ether-like oxygen atom at the end of a perfluorocarbon group with 1 to 10 carbon atoms in a divalent state or between carbon-carbon bonds.

[0140] (CH2=CH-)2R 41 (4)

[0141] In equation (4), R 41 It refers to a perfluorocarbon group with 1 to 10 carbon atoms in a divalent state, or a group having an ether-like oxygen atom at the end of a perfluorocarbon group with 1 to 10 carbon atoms in a divalent state or between carbon-carbon bonds.

[0142] As specific examples of the monomers shown in equation (3), we can cite CF2=CFO(CF2)2OCF=CF2, CF2=CFO(CF2)3OCF=CF2, CF2=CFO(CF2)4OCF=CF2, CF2=CFO(CF2)6OCF=CF2, CF2=CFO(CF2)8OCF=CF2, CF2=CFO(CF2)2OCF(CF3)CF2 ...2)8OCF=CF2, CF2 2)2O(CF(CF3)CF2O)2CF=CF2, CF2=CFOCF2O(CF2CF2O)2CF=CF2, CF2=CFO(CF2O)3O(CF(CF3)CF2O)2C F=CF2, CF2=CFOCF2CF(CF3)O(CF2)2OCF(CF3)CF2OCF=CF2 and CF2=CFOCF2CF2O(CF2O)2CF2CF2OCF=CF2.

[0143] Among the monomers shown in Equation (3), specific examples of more preferred monomers include CF2=CFO(CF2)3OCF=CF2 (hereinafter also referred to as "C3DVE") and CF2=CFO(CF2)4OCF=CF2 (hereinafter also referred to as "C4DVE").

[0144] Specific examples of the monomers shown in equation (4) include CH2=CH(CF2)2CH=CH2, CH2=CH(CF2)4CH=CH2 and CH2=CH(CF2)6CH=CH2.

[0145] Among the monomers shown in formula (4), CH2=CH(CF2)6CH=CH2 (hereinafter also referred to as "C6DV") is a more preferred example.

[0146] Among them, BO is preferably C3DVE or C4DVE.

[0147] As R Hal More preferred examples of monomers include monomers having bromine atoms and monomers having iodine atoms.

[0148] Specific examples of monomers containing bromine atoms include CF2=CFOCF2CF2CF2OCF2CF2Br, bromotrifluoroethylene, 4-bromo-3,3,4,4-tetrafluorobutene-1 (BTFB), bromoethylene, 1-bromo-2,2-difluoroethylene, perfluoroallyl bromide, 4-bromo-1,1,2-trifluorobutene-1, 4-bromo-1,1,3,3,4,4-hexafluorobutene, 4-bromo-3-chloro-1,1,3,4,4-pentafluorobutene, 6-bromo-5,5,6,6-tetrafluorohexene, and 4-bromoperfluorobutene-1, 3,3-difluoroallyl bromide. Additionally, 2-bromo-perfluoroethyl perfluorovinyl ether and CF2Br-R can be cited. f -O-CF=CF2(R f Fluorinated compounds such as perfluoroalkylene (CF2BrCF2O-CF=CF2), ROCF=CFBr and ROCBr=CF2 (where R is a lower alkyl or fluoroalkyl) are examples of fluorinated vinyl ethers. Specifically, CH3OCF=CFBr and CF3CH2OCF=CFBr are examples.

[0149] As a specific example of a monomer containing an iodine atom, the formula can be given: CHR=CH-Z-CH2CHR-I (where R is -H or -CH3; Z is a straight-chain or branched C1~C1 group containing one or more ether oxygen atoms, depending on the case). 18 Iodinated olefins of the (per)fluoroalkylene group, or (per)fluoropolyoxyalkylene group disclosed in U.S. Patent No. 5,674,959. Additionally, the formula I(CH2CF2CF2) disclosed in U.S. Patent No. 5,717,036 can be cited as an example. n OCF=CF2 and ICH2CF2O[CF(CF3)CF2O] n Unsaturated ethers with CF=CF2, etc. (where n=1~3). Examples include iodoethylene, 4-iodine-3,3,4,4-tetrafluorobutene-1 (ITFB), 3-chloro-4-iodine-3,4,4-trifluorobutene, 2-iodine-1,1,2,2-tetrafluoro-1-(vinyloxy)ethane, 2-iodine-1-(perfluorovinyloxy)-1,1,-2,2-tetrafluoroethylene, 1,1,2,3,3,3-hexafluoro-2-iodine-1-(perfluorovinyloxy)propane, 2-iodoethyl vinyl ether, 3,3,4,5,5,5-hexafluoro-4-iodopentene, and iodotrifluoroethylene. Also examples include allyl iodine and 2-iodine-perfluoroethyl perfluorovinyl ether.

[0150] From the perspective of polymerization reactivity, R CNPreferably, it has a polymerizable unsaturated bond, and more preferably, it has one polymerizable unsaturated bond. Specific examples of polymerizable unsaturated bonds include carbon-carbon double bonds (C=C) and carbon-carbon triple bonds (C≡C).

[0151] From the perspective of superior release properties and heat resistance of solid compositions, R CN The preferred monomer is the one shown in formula (5).

[0152] CR 51 R 52 =CR 53 -R 54 -CN (5)

[0153] In equation (5), R 51 R 52 and R 53 Each can independently represent a hydrogen atom, a fluorine atom, or a methyl group, R 54 It refers to a perfluorocarbon group with 1 to 10 carbon atoms in a divalent state, or a group having an ether-like oxygen atom at the end of a perfluorocarbon group with 1 to 10 carbon atoms in a divalent state or between carbon-carbon bonds.

[0154] From R CN Based on the excellent polymerization reactivity of R, R is preferred. 51 R 52 and R 53 It is a fluorine atom or a hydrogen atom, more preferably R 51 R 52 and R 53 R is particularly preferred due to its superior release properties and heat resistance, consisting entirely of fluorine atoms or entirely of hydrogen atoms in cross-linked rubber articles. 51 R 52 and R 53 It consists entirely of fluorine atoms.

[0155] R 54 It can be any of the following: linear, branched, and cyclic, preferably linear or branched. R 54 The number of carbon atoms is preferably 2 to 8, more preferably 3 to 7, even more preferably 3 to 6, and particularly preferably 3 to 5.

[0156] R 54 The rubber may be selected from those with ether-like oxygen atoms, and from the perspective of superior rubber properties, those with ether-like oxygen atoms are preferred.

[0157] R 54 The number of ether oxygen atoms in the sample is preferably 1 to 3, and particularly preferably 1 or 2.

[0158] Specific examples of the monomers shown in formula (5) include CF2=CFOCF2CF(CF3)OCF2CF2CN (hereinafter also referred to as "8CNVE"), CF2=CFO(CF2)5CN (hereinafter also referred to as "MV5CN"), CF2=CFOCF2CF2CF2OCF(CF3)CN and CF2=CFO(CF2)3CN. From the perspective of superior release properties and heat resistance of the solid composition, 8CNVE or MV5CN is preferred.

[0159] POAVE is the compound shown in formula (6).

[0160] CF2 = CF(OCF2CF2) n -(OCF2) m -OR f2 (6)

[0161] In equation (6), R f2 It represents a perfluoroalkyl group with 1 to 4 carbon atoms, where n represents an integer from 0 to 3, m represents an integer from 0 to 4, and n+m represents an integer from 1 to 7.

[0162] R f2 In this context, perfluoroalkyl groups can be either straight-chain or branched. R f2 The preferred number of carbon atoms is 1 to 3.

[0163] When n is 0, m is preferably 1 or 2. When n is 1, m is preferably an integer from 2 to 4. When n is 2 or 3, m is preferably 0. When n is preferably an integer from 1 to 3.

[0164] R f2 When the number of carbon atoms, n, and m are within the above range, the cross-linked rubber articles exhibit excellent low-temperature properties, and the productivity of the solid composition is improved.

[0165] Specific examples of POAVE include the following substances. It should be noted that the parentheses following the formula represent the abbreviation of the compound.

[0166] CF2=CF-OCF2CF2-(OCF2)4-OCF3(C9PEVE),

[0167] CF2=CF-OCF2CF2-(OCF2)2-OCF3(C7PEVE),

[0168] CF2=CF-(OCF2CF2)2-OCF2CF3(EEAVE)、

[0169] CF2=CF-(OCF2CF2)3-OCF2CF3(EEEAVE)、

[0170] CF2=CF-OCF2-OCF3, CF2=CF-OCF2-OCF2-OCF3

[0171] From the viewpoint of superior low-temperature properties of cross-linked rubber articles and higher productivity of solid compositions, C9PEVE, C7PEVE, EEAVE, or EEEAVE are preferred as POAVE.

[0172] It should be noted that these compounds can be manufactured using the corresponding alcohols as raw materials, through the method described in International Publication No. 00 / 056694.

[0173] The amount of other monomers used relative to the amount of a specific monomer is preferably 0 to 20 mol%, more preferably 0 to 10 mol%, and even more preferably 0 to 5 mol%.

[0174] The specific monomer preferably consists only of TFE and PAVE, or contains TFE and PAVE and includes components selected from BO and R. Hal and R CN At least one monomer in the group.

[0175] (Polymerization initiator)

[0176] In step 1 of this manufacturing method, the specific monomer is preferably polymerized in the presence of a polymerization initiator.

[0177] As polymerization initiators, oil-soluble free radical initiators, water-soluble free radical initiators, or water-soluble redox catalysts are preferred.

[0178] Specific examples of oil-soluble free radical initiators include oil-soluble organic peroxides such as tert-butyl peroxypentanoate and diisopropyl peroxydicarbonate.

[0179] Specific examples of water-soluble free radical initiators include persulfates such as ammonium persulfate and potassium persulfate; and water-soluble organic peroxides such as disuccinic acid peroxide, diglutaric acid peroxide, and tert-butyl hydroperoxide.

[0180] As a water-soluble redox catalyst, a combination of oxidants such as bromic acid or its salts, chloric acid or its salts, persulfate or its salts, permanganate or its salts, and hydrogen peroxide with reducing agents such as sulfurous acid or its salts, bisulfite or its salts, thiosulfate or its salts, organic acids, and inorganic salts is preferred. Potassium persulfate or ammonium persulfate is preferred as a persulfate. Sodium sulfite is preferred as a sulfite. As an inorganic salt, combinations of sulfate anions, sulfite anions, or chloride anions with metal ions are possible. As a metal ion, transition metals are preferred, including manganese, iron, cobalt, nickel, copper, zinc, cerium, and silver ions, with iron ions being preferred. As an inorganic salt, ferric(II) sulfate is preferred.

[0181] The polymerization initiator is preferably an oil-soluble free radical initiator or a water-soluble free radical initiator. From the perspective of being able to manufacture fluoropolymers more efficiently, a water-soluble free radical initiator is preferred, and persulfate or water-soluble organic peroxide is even more preferred.

[0182] Two or more polymerization initiators can be used together.

[0183] The amount of polymerization initiator used is preferably 0.01 to 5 parts by mass relative to 100 parts by mass of a specific monomer, more preferably 0.01 to 3 parts by mass, and even more preferably 0.01 to 2 parts by mass.

[0184] (Chain transfer agent)

[0185] In step 1 of this manufacturing process, the specific monomer is preferably polymerized in the presence of a chain transfer agent.

[0186] Specific examples of chain transfer agents include chain transfer agents having iodine atoms, ethyl acetate, methanol, ethanol, tert-butyl methyl ether, diethyl ether, n-pentane, cyclohexane, methane, and propane, with chain transfer agents having iodine atoms being preferred. By using a chain transfer agent having iodine atoms to polymerize specific monomers, fluoropolymers with iodine atoms at the ends can be produced.

[0187] The compound shown in formula (I) is preferred as a chain transfer agent having iodine atoms.

[0188] (R f )-(X)2 (I)

[0189] In equation (I), R f It is a fluoroalkylene or aromatic cyclic group having 1 to 16 carbon atoms.

[0190] X is an iodine atom or a bromine atom, with at least one being an iodine atom.

[0191] R f The fluoroalkyl group can be linear or branched. As R f Perfluoroalkylene groups are preferred.

[0192] Ideally, X should consist entirely of iodine atoms.

[0193] Specific examples of compounds represented by formula (I) include 1,2-diiodoperfluoroethane, 1,3-diiodoperfluoropropane, 1,4-diiodoperfluorobutane (hereinafter also referred to as "C4DI"), 1,5-diiodoperfluoropentane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane, 1,3-diiodo-2-chloroperfluoropropane, 1,5-diiodo-2,4-dichloroperfluoropentane, 1,12-diiodoperfluorododecane, and 1,16-diiodoperfluorohexadecane. Alkanes, diiodomethane, 1,2-diiodoethane, 1,3-diiodopropane, (2-iodoethyl)-substituted derivatives of benzene, 1-iodo-4-bromoperfluorobutane, 1-iodo-6-bromoperfluorohexane, 1-iodo-8-bromoperfluorooctane, 1-bromo-2-iodoperfluoroethane, 1-bromo-3-iodoperfluoropropane, 2-bromo-3-iodoperfluorobutane, 3-bromo-4-iodoperfluorobutene-1, 2-bromo-4-iodoperfluorobutene-1, monoiodomonobromo-substituted derivatives of benzene, and diiodomonobromo-substituted derivatives.

[0194] C4DI is preferred as the compound represented by formula (I).

[0195] The amount of chain transfer agent used is preferably 0.1 to 10 parts by mass relative to 100 parts by mass of a specific monomer, more preferably 0.1 to 5 parts by mass, and even more preferably 0.1 to 1 part by mass.

[0196] From the perspective of obtaining a solid composition with superior crosslinking properties, this manufacturing method preferably includes specific monomers selected from BO and R. Hal and R CN At least one monomer in the group, or the first aqueous dispersion, contains a chain transfer agent containing iodine atoms.

[0197] (means)

[0198] Step 1 is a step in which the specific monomer is polymerized in the first aqueous dispersion to obtain a second aqueous dispersion containing a second fluoropolymer.

[0199] Specific monomers are added to the reaction system (i.e., the polymerization reactor) using conventional methods. For example, the specific monomers can be added to the reaction system continuously or intermittently at a polymerization pressure that is within a specified range. Alternatively, the specific monomers can be dissolved in an aqueous medium, and the resulting solution can be added to the reaction system continuously or intermittently.

[0200] When using a polymerization initiator, it can be added to the reaction system all at once or in batches. Similarly, when using other components (such as chain transfer agents), these components can also be added to the reaction system all at once or in batches.

[0201] The polymerization temperature is preferably 10~95℃, more preferably 15~90℃.

[0202] The polymerization pressure is preferably 0.5~4.0 MPaG, more preferably 0.6~3.5 MPaG.

[0203] In the case of batch processing, the polymerization time is preferably 90 to 1,000 minutes, more preferably 90 to 700 minutes.

[0204] The polymerization of a particular monomer is preferably carried out in the absence of a substantially emulsifier.

[0205] The emulsifiers mentioned above can be cited as examples.

[0206] "Substantially no emulsifier" means that the content of emulsifier is less than 0.03 ppm by mass relative to the total mass of the aqueous medium contained in the first aqueous dispersion, preferably less than 0.02 ppm by mass, and more preferably 0 ppm by mass.

[0207] (Second fluoropolymer)

[0208] A second fluoropolymer is manufactured through step 1 of this manufacturing method. The second fluoropolymer comprises units based on a specific monomer.

[0209] In the second fluoropolymer, the TFE unit is 5 to 85 mol% relative to the total of the TFE unit and the PAVE unit, preferably 40 to 80 mol%, more preferably 50 to 75 mol% from the viewpoint of being able to manufacture the second fluoropolymer more efficiently, and even more preferably 60 to 70 mol%.

[0210] In the second fluoropolymer, the PAVE unit comprises 15 to 95 mol% relative to the total of TFE and PAVE units, preferably 20 to 60 mol%, more preferably 25 to 50 mol%, and even more preferably 30 to 40 mol%, from the perspective of enabling more efficient production of the second fluoropolymer. The preferred amount is the same when PMVE or PPVE units are used as PAVE units.

[0211] In the second fluoropolymer, the total content of TFE units and PAVE units is preferably 80 to 100 mol% relative to all units of the second fluoropolymer, more preferably 90 to 100 mol%, and even more preferably 95 to 100 mol%.

[0212] The second fluoropolymer comprises TFE units and PAVE units, and preferably also comprises units based on other monomers. Examples of units based on other monomers include units based on other monomers among the specific monomers mentioned above.

[0213] The TFE unit is preferably 35 to 80 mol% relative to all units in the second fluoropolymer, more preferably 47 to 75 mol%, and even more preferably 59 to 70 mol%.

[0214] The PAVE unit is preferably 20 to 60 mol% relative to all units in the second fluoropolymer, more preferably 25 to 50 mol%, and even more preferably 30 to 40 mol%.

[0215] The percentage of units based on other monomers is preferably 0.01 to 5 mol% relative to all units in the second fluoropolymer, more preferably 0.05 to 3 mol%, and even more preferably 0.10 to 1 mol%.

[0216] From the perspective of improving the crosslinkability of the solid composition, the second fluoropolymer preferably includes at least one selected from the group consisting of polymerizable unsaturated bonds, chlorine atoms, bromine atoms, iodine atoms and nitrile groups, and more preferably includes at least one selected from the group consisting of polymerizable unsaturated bonds, iodine atoms and nitrile groups.

[0217] Preferably, at least one of the above-mentioned components is included in the end and side chain of the second fluoropolymer.

[0218] Step 1 generates a second fluoropolymer, resulting in a second aqueous dispersion containing particles of the second fluoropolymer dispersed in an aqueous medium.

[0219] (Second aqueous dispersion)

[0220] The second aqueous dispersion is an aqueous dispersion containing the second fluoropolymer obtained through step 1. In other words, the second aqueous dispersion is an aqueous dispersion containing particles of a fluoropolymer (hereinafter also referred to as "specific particles") dispersed in an aqueous medium, wherein the fluoropolymer includes the second fluoropolymer.

[0221] Specific particles may optionally contain a first fluoropolymer.

[0222] The second aqueous dispersion may contain a first fluoropolymer dispersed in particulate form.

[0223] -Specific particles-

[0224] The preferred manner in which the fluoropolymer contained in the specific particles is the same as that of the second fluoropolymer described above.

[0225] From the perspective of the dispersion stability of specific particles, the content of specific particles in the second aqueous dispersion relative to the total mass of the second aqueous dispersion is preferably 1 to 50% by mass, more preferably 10 to 40% by mass, and even more preferably 15 to 30% by mass.

[0226] The content (solid component concentration) of specific particles in the second aqueous dispersion can be determined, for example, by the following methods.

[0227] After heating 2.0g of the second aqueous dispersion at 170℃ for 20 minutes, the mass of the residue was weighed, and the concentration of the solid component was calculated using the following formula.

[0228] "Solid component concentration (mass %) = 100 × mass of heating residue of the second aqueous dispersion (g) / mass of the second aqueous dispersion (2.0g)"

[0229] The average particle size of the specific particles is preferably less than 1 μm, and more preferably less than 500 nm, and even more preferably less than 400 nm, from the perspective of the dispersion stability of the specific particles.

[0230] From the perspective of recovery efficiency in step 2 described later, the average particle size of the specific particles is preferably 50 nm or more, more preferably 60 nm or more, and even more preferably 80 nm or more.

[0231] The average particle size of a specific particle is calculated by analyzing the autocorrelation function obtained from dynamic light scattering using the monodisperse cumulative method.

[0232] -Aqueous medium-

[0233] The specific examples of the aqueous medium contained in the second aqueous dispersion are the same as those of the specific examples of the aqueous medium contained in the first aqueous dispersion described above.

[0234] From the perspective of the dispersion stability of specific particles, the content of the aqueous medium relative to the total mass of the second aqueous dispersion is preferably 50 to 99% by mass, more preferably 60 to 99% by mass, and even more preferably 70 to 99% by mass.

[0235] -Emulsifier-

[0236] From the perspective of further enhancing the effects of the present invention, the content of emulsifier in the second aqueous dispersion relative to the total mass of the second aqueous dispersion is preferably 100 ppm by mass or less, more preferably 75 ppm by mass or less, even more preferably 50 ppm by mass or less, even more preferably 1 ppm by mass or less, and particularly preferably 25 ppb by mass or less. Furthermore, it is also preferably below the quantitative limit of the determination method in the examples. One ppb by mass is an example of a lower limit. It is preferable that no emulsifier is used in the second aqueous dispersion.

[0237] The emulsifier content can be determined using the same method as for the first aqueous dispersion described above.

[0238] Specific examples of emulsifiers are as described above. It should be noted that the emulsifier in the second aqueous dispersion may or may not be water-soluble.

[0239] <Process 2>

[0240] In step 2 of this manufacturing method, the second aqueous dispersion obtained in step 1 is subjected to stirring treatment, and the solids are recovered to obtain a solid composition.

[0241] (Stirring process)

[0242] As a specific method of mixing, one example is the use of a mixing device that rotates a mixing shaft equipped with mixing blades.

[0243] Specific examples of the shape of the aforementioned stirring blades include paddle blades, inclined paddle blades, propeller blades, disc blades, three-bladed swept blades, anchor blades, turbine blades, and disc turbine blades. From the perspective of excellent stirring efficiency, paddle blades or disc turbine blades are preferred.

[0244] The number of the above-mentioned stirring blades is preferably 1 to 10, more preferably 2 to 4.

[0245] Specific examples of the shape of the tank used in the above-mentioned mixing process include cylindrical, conical, elliptical cylindrical, square cylindrical, and pyramidal shapes. From the perspective of mixing and flowability, the cylindrical shape is preferred.

[0246] Baffles can also be installed in the mixing device.

[0247] The stirring time is preferably 0.1 to 24 hours, more preferably 0.1 to 12 hours, and even more preferably 0.1 to 6 hours.

[0248] The circumferential speed of the stirring is preferably 2~50 m / s, more preferably 3~30 m / s, and even more preferably 5~30 m / s. The circumferential speed can be constant or variable during stirring. The above-mentioned circumferential speed is also preferably faster than the circumferential speed in step 1. The above-mentioned circumferential speed of stirring refers to the speed of the blades at the leading edge of the stirring blades.

[0249] The temperature of the aqueous dispersion during stirring is preferably 10~90℃, more preferably 10~80℃, and even more preferably 15~70℃.

[0250] (Solid matter)

[0251] The solid is obtained by the above stirring process and contains fluoropolymers.

[0252] It should be noted that, in this specification, "solid matter" refers to a solid that is not stably dispersed in an aqueous medium. Even if the dispersed phase stably dispersed in an aqueous medium is insoluble in the aqueous medium, it is not considered a solid matter. For example, in the second aqueous dispersion after stirring, the insoluble components (e.g., specific particles) contained in the dispersion do not include the dispersed phase stably dispersed in the aqueous medium, but precipitates and floating matter are included in the solid matter. Examples of such solid matter include, for instance, aggregates of specific particles.

[0253] Examples of stable dispersed phases include those obtained by means of the five types of A filter paper specified in JIS P 3801 [Filter Paper (for Chemical Analysis)].

[0254] The solid composition of the present invention can be obtained by recycling the above-mentioned solids.

[0255] Filtration and centrifugation are examples of methods for recycling solids, with filtration being the preferred method.

[0256] <Cleaning>

[0257] The manufacturing method preferably also includes a step of cleaning the recovered solid composition (hereinafter also referred to as "step 3").

[0258] Step 3 removes other components (e.g., emulsifiers, monomers, polymerization initiators, and their reactants) from the solid composition, making it easy to obtain cross-linked rubber articles with the desired physical properties.

[0259] As a cleaning fluid in the cleaning process, the above-mentioned aqueous media can be cited as examples, with water being preferred, and ultrapure water being more preferred from the perspective of having a low content of impurities that may be a cause of cross-linking.

[0260] Specific examples of cleaning methods include immersing the solid composition in a cleaning solution and stirring, and spraying the solid composition with a cleaning solution. The solid composition can be cleaned and dehydrated repeatedly. Specific examples of dehydration methods include extrusion and centrifugal separation.

[0261] The amount of cleaning liquid in the cleaning process is preferably 1 to 20 times the total mass of the solid composition, more preferably 1 to 10 times, and even more preferably 1 to 5 times.

[0262] The temperature of the cleaning solution in the cleaning process is preferably 5~80℃, more preferably 10~70℃, and even more preferably 20~60℃.

[0263] [Solid Composition]

[0264] This manufacturing method yields a solid composition.

[0265] The solid composition of the present invention (hereinafter also referred to as "the solid composition") comprises a fluoropolymer containing TFE units and PAVE units and is substantially free of emulsifiers, satisfying requirement X described below.

[0266] It should be noted that, in this specification, "solid composition" refers to a composition in which the solid component mass is 99% or more. The mass of the solid component is calculated based on the mass before and after heating using the following method.

[0267] After heating 2.0g of the solid composition at 170°C for 20 minutes, the mass of the residue was weighed, and the mass of the solid component was calculated using the following formula.

[0268] Mass of solid component (mass%) = 100 × (mass of residue) / (mass of solid composition)

[0269] Fluoropolymers

[0270] The fluoropolymer contained in this solid composition comprises TFE units and PAVE units.

[0271] The details of the TFE unit and the PAVE unit are the same as those of the TFE unit and the PAVE unit in the first fluoropolymer described above, and the preferred methods are also the same.

[0272] The fluoropolymer contained in this solid composition preferably includes a second fluoropolymer, more preferably a second fluoropolymer. That is, the preferred manner in which the fluoropolymer contained in this solid composition is the same as that of the second fluoropolymer described above.

[0273] This solid composition optionally includes a first fluoropolymer.

[0274] It should be noted that, in this specification, when there is only one type of fluoropolymer, "all units of the fluoropolymer" refers to all units contained in that single type of fluoropolymer. Furthermore, when a specific particle contains two or more types of fluoropolymers, "all units of the fluoropolymer" refers to all units contained in the two or more types of fluoropolymers.

[0275] The fluoropolymer contained in this solid composition may include units based on monomers other than TFE and PAVE units. Examples include units based on other monomers among the specific monomers described above.

[0276] From the perspective of superior crosslinking properties, the fluoropolymer contained in this solid composition preferably includes at least one selected from the group consisting of polymerizable unsaturated bonds, chlorine atoms, bromine atoms, iodine atoms, and nitrile groups, and more preferably includes at least one selected from the group consisting of polymerizable unsaturated bonds, iodine atoms, and nitrile groups. Preferably, at least one of the above-mentioned elements is included in at least one of the ends and side chains of the fluoropolymer.

[0277] As specific monomers, in addition to TFE and PAVE, any of the polymerizable unsaturated bonds, chlorine atoms, bromine atoms, iodine atoms, and nitrile groups can be introduced into the side chains or ends of fluoropolymers by using other monomers mentioned above. Furthermore, by polymerizing specific monomers using chain transfer agents containing iodine atoms, iodine atoms can be introduced into the ends of fluoropolymers.

[0278] When the fluoropolymer contained in a particular particle has iodine atoms, the proportion of iodine atoms relative to the total mass of the fluoropolymer is preferably 0.01 to 5.00% by mass, more preferably 0.01 to 2.00% by mass, and even more preferably 0.01 to 1.00% by mass.

[0279] The content of the fluoropolymer relative to the total mass of the solid composition is preferably 99.0 to 100% by mass, more preferably 99.5 to 100% by mass, and even more preferably 99.8 to 100% by mass.

[0280] <Emulsifier>

[0281] The solid composition is essentially free of emulsifiers.

[0282] "The solid composition is substantially free of emulsifiers" means that no emulsifiers are used in the manufacturing process of the solid composition, the solid composition is free of emulsifiers, or, if the solid composition contains the aforementioned emulsifiers, the total content of emulsifiers relative to the total mass of the solid composition is less than 500 ppb.

[0283] When the solid composition contains an emulsifier, the total content of the emulsifier relative to the total mass of the solid composition is preferably 250 ppb or less by mass, more preferably 100 ppb or less by mass, and even more preferably 50 ppb or less by mass. Furthermore, it is also preferably below the quantitative limit of the determination method in the examples. As a lower limit, more than 0 ppb by mass can be cited.

[0284] It should be noted that, in the above, the number of emulsifier types contained in the solid composition refers to the number of emulsifier types whose content exceeds the quantitative limit, excluding emulsifiers below the quantitative limit. Specifically, when determining the content of emulsifier X, emulsifier Y, and emulsifier Z in the solid composition, if the content of emulsifier X and emulsifier Y both exceed the quantitative limit, and the content of emulsifier Z is below the quantitative limit, it means that the solid composition contains two emulsifiers, emulsifier X and emulsifier Y.

[0285] The content of emulsifier can be determined by the method for determining the content of emulsifier in the above-described method for manufacturing solid compositions.

[0286] The solid composition may contain emulsifiers as described above.

[0287] The solid composition preferably does not contain any of the compounds (emulsifiers) represented by formulas (S1) to (S4). When an emulsifier is not used when manufacturing the first fluoropolymer contained in the first aqueous dispersion, the amount of compounds represented by any of formulas (S1) to (S4) can be suppressed, and the adjustment of the content of these compounds becomes easy.

[0288] H-(CF2) n1 -COOM (S1)

[0289] F-(CF2) n1 -COOM (S2)

[0290] H-(CF2) n2 -SO3M (S3)

[0291] F-(CF2) n2 -SO3M (S4)

[0292] In equations (S1) to (S4),

[0293] n1 is an integer between 3 and 19.

[0294] n² is an integer between 4 and 20.

[0295] M can be a hydrogen atom, Na, K, or NH4 independently.

[0296] In the solid composition of the present invention, the total content of the compounds represented by any of formulas (S1) to (S4) relative to the total mass of the solid composition is preferably 25 ppb or less by mass, more preferably 20 ppb or less by mass. Furthermore, it is also preferably below the quantitative limit of the determination method in the examples. As a lower limit, more than 0 ppb by mass can be cited.

[0297] <Requirement X>

[0298] The solid composition of the present invention satisfies requirement X. When requirement X is satisfied, the solid composition has a low content of crosslinking-inhibiting components, resulting in excellent effects of the present invention.

[0299] Requirement X: In a mixture obtained by mixing a solid composition and water at pH 6 in such a way that the mass of water is 5 times the mass of the solid composition, the pH of the mixture at 23°C is greater than or equal to that of the mixture 24 hours after mixing.

[0300] The pH of the above mixture at 23°C after 24 hours of mixing is 4 or higher, more preferably 5 or higher. Furthermore, the pH is preferably 12 or lower, more preferably 10 or lower.

[0301] The pH of the above mixture was measured after the solid composition and water were mixed and allowed to stand at 23°C for 24 hours. The pH value can be measured using a known pH meter.

[0302] As an example of a method for obtaining a solid composition that satisfies the above requirement X, a method can be given that the above stirring conditions are adjusted without using a coagulant.

[0303] <Flocculant>

[0304] In this manufacturing method, the aqueous dispersion is stirred to recover solids from the aqueous dispersion to obtain a solid composition. Therefore, acid coagulation, alkali coagulation, and coagulation using coagulants are not performed. That is, since the solid composition does not contain residues of coagulants used in acid coagulation, alkali coagulation, and coagulation using coagulants, the above-mentioned requirement X can be satisfied.

[0305] As a coagulant, in the case of acid coagulation, a solution containing acid is added. Examples of acids added include hydrochloric acid, nitric acid, sulfuric acid, oxalic acid, and hydrofluoric acid.

[0306] As a form of alkaline coagulation, a solution containing an alkali is added. Examples of alkalis include sodium hydroxide, potassium hydroxide, and ammonium carbonate.

[0307] As a coagulation process utilizing a coagulant, known coagulants are used, including aluminum salts, calcium salts, magnesium salts, and ammonium salts. Specifically, examples include ammonium carbonate, aluminum sulfate, alum (with the general formula M'Al(SO4)2·12H2O [where M' is a monovalent cation other than lithium], calcium nitrate, and magnesium sulfate.

[0308] The solid composition of the present invention is substantially free of coagulants.

[0309] "The solid composition is substantially free of coagulants" means that no coagulants are used in the manufacturing process of the solid composition, the solid composition is free of emulsifiers, or, if the solid composition contains the aforementioned coagulants, the total content of the coagulants is less than 25 ppb by mass relative to the total mass of the solid composition.

[0310] When the solid composition contains a coagulant, the total content of the coagulant relative to the total mass of the solid composition is preferably 25 ppb or less by mass, more preferably 20 ppb or less by mass. As a lower limit, more than 0 ppb by mass can be cited.

[0311] <Storage Modulus>

[0312] The storage modulus G' of the solid composition at 100°C and 50 cpm is preferably 300 kPa or more, more preferably 350 kPa or more. From the perspective of the moldability of the crosslinked rubber article, the above-mentioned storage modulus G' is preferably 850 kPa or less, more preferably 800 kPa or less.

[0313] The storage modulus G' at 100°C and 50 cpm is a value determined according to ASTM D5289 and ASTM D6204. The detailed measurement conditions are shown in the example.

[0314] As an example of a method to adjust the aforementioned energy storage modulus, one could cite methods such as adjusting the usage amount and usage sequence of each individual cell.

[0315] Solid compositions are also preferably fluorinated elastomers.

[0316] "Fluoropolymers" refer to fluoropolymers that are elastic without a melting point, with a storage modulus G' of 80 or higher at 100°C and 50 cpm as measured according to ASTM D6204, as determined by ASTM D6204. They are distinct from fluoropolymers.

[0317] <Metal content>

[0318] From the viewpoint of reducing environmental pollution during use, the total metal content of the solid composition relative to the total mass of the solid composition is preferably 50 ppm by mass or less, more preferably 20 ppm by mass or less, and even more preferably 10 ppm by mass or less. Furthermore, it is also preferably below the detection limit of the determination method described in the examples below. As a lower limit, 0.1 ppm by mass can be cited as an example.

[0319] The above metal content is the total value of the contents of 29 metal elements (Fe, Na, K, Li, Be, Mg, Al, Ca, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Rb, Sr, Zr, Mo, Ag, Cd, In, Sn, Cs, Ba, Pb and Bi) determined by inductively coupled plasma mass spectrometry using the absolute calibration curve method.

[0320] As a method for determining the metal content of a solid composition, an example is to perform an ashing treatment on the solid composition and then use an inductively coupled plasma mass spectrometry (ICP-MS) device to determine the metal content of the liquid obtained by dissolving the ash in acid. Detailed determination conditions are shown in the examples.

[0321] The solid composition manufactured by this method can be easily adjusted to the above-mentioned range without the need for a metal-containing coagulant during recycling.

[0322] [use]

[0323] This manufacturing method is preferably used for the manufacture of cross-linked rubber articles. That is, the solid composition obtained by this manufacturing method is preferably used for the manufacture of cross-linked rubber articles.

[0324] Specific examples of cross-linked rubber articles include sealing materials and cushioning materials such as rings, seals, oil seals, gaskets, diaphragms, and sheets. Other examples include sealing materials for semiconductor devices, components for oil drilling, wire sheathing materials, heat-resistant and chemical-resistant sealing materials, heat-resistant and oil-resistant sealing materials, corrosion-resistant rubber coatings, sealing materials for urea-based greases, rubber coatings, adhesive rubber, hoses, pipes, calendered sheets (rollers), sponges, rubber rollers, heat sinks, solution cross-linked compounds, rubber sponges, bearing seals, linings, automotive insulating sheets, insulating sheets for electronic equipment, rubber tapes, seals / valves, fender materials, fiber / nonwoven fabrics, basic sealing materials, rubber gloves, stators for single-shaft eccentric screw pumps, components for urea SCR systems, vibration damping agents, shock absorbers, and sealants.

[0325] The cross-sectional shape of the aforementioned rings, seals, and oil seals is not particularly limited. For example, shapes such as O-shapes, quadrilaterals, and clamp joints can be used. In addition, irregular shapes such as D-shapes, X-shapes, Y-shapes, L-shapes, T-shapes, and V-shapes can also be used.

[0326] Examples of fields that use fluororubber include semiconductors, beverage and food manufacturing equipment, pharmaceutical manufacturing equipment, medical components, chemical delivery machinery, nuclear power plant machinery, sheet metal processing equipment, general industry, electrical equipment, fuel cells, electronic components, optical machinery components, aerospace machinery components, petrochemical plant machinery, oil and gas energy resource exploration and extraction machinery components, oil purification and oil transportation machinery components, automobiles, aircraft, space and rockets, ships, chemical industries such as chemical plants, pharmaceuticals, photographic equipment such as developing machines, printing machinery, coating equipment, analytical and physical chemical machinery such as instruments, food machinery for food factories and household products, etc.

[0327] In the aforementioned semiconductor-related fields, these devices can be used in semiconductor manufacturing equipment, liquid crystal panel manufacturing equipment, plasma panel manufacturing equipment, plasma display panel manufacturing equipment, plasma-addressed liquid crystal panel manufacturing equipment, organic electroluminescent (EL) panel manufacturing equipment, field emission display panel manufacturing equipment, solar cell substrate manufacturing equipment, and semiconductor transport equipment. More specifically, examples include chemical vapor deposition (CVD) equipment, gas control equipment such as semiconductor gas control equipment, dry etching equipment, wet etching equipment, plasma etching equipment, reactive ion etching equipment, reactive ion beam etching equipment, sputtering etching equipment, ion beam etching equipment, oxidation diffusion equipment, sputtering equipment, ashing equipment, plasma ashing equipment, cleaning equipment, ion implantation equipment, plasma CVD equipment, exhaust equipment, exposure equipment, polishing equipment, film deposition equipment, dry etching and cleaning equipment, ultraviolet (UV) / ozone cleaning equipment, ion beam cleaning equipment, laser beam cleaning equipment, plasma cleaning equipment, and gas etching and cleaning equipment. Extraction and cleaning equipment, Soxhlet extraction and cleaning equipment, high-temperature and high-pressure extraction and cleaning equipment, microwave extraction and cleaning equipment, supercritical extraction and cleaning equipment, cleaning equipment using hydrofluoric acid, hydrochloric acid, sulfuric acid, ozone water, etc., steppers, coating and developing machines, chemical mechanical polishing (CMP) equipment, excimer laser exposure machines, chemical piping, gas piping, plasma treatment equipment (e.g., nitrogen trifluoride (NF3) plasma treatment, oxygen plasma treatment, fluorine plasma treatment, etc.), heat treatment film forming equipment, wafer transport machines, wafer cleaning equipment, silicon wafer cleaning equipment, silicon wafer processing equipment, reduced pressure CVD (LPCVD) equipment, lamp annealing equipment, reflow equipment, etc.

[0328] In the aforementioned semiconductor-related fields, these devices can be used in semiconductor manufacturing equipment, organic electroluminescent (EL) panel manufacturing equipment, field emission display panel manufacturing equipment, plasma-addressed liquid crystal panel manufacturing equipment, plasma display panel manufacturing equipment, liquid crystal panel manufacturing equipment, solar cell substrate manufacturing equipment, plasma panel manufacturing equipment, semiconductor transport equipment, etc. More specifically, examples include reactive ion beam etching equipment, ion beam etching equipment, sputtering etching equipment, plasma etching equipment, reactive ion etching equipment, dry etching equipment, wet etching equipment, chemical vapor deposition (CVD) equipment, gas control equipment such as semiconductor gas control equipment, oxidation diffusion equipment, sputtering equipment, plasma ashing equipment, ashing equipment, cleaning equipment, ion implantation equipment, plasma CVD equipment, exhaust equipment, exposure equipment, polishing equipment, film deposition equipment, dry etching and cleaning equipment, ultraviolet (UV) / ozone cleaning equipment, ion beam cleaning equipment, laser beam cleaning equipment, plasma cleaning equipment, and gas etching and cleaning equipment. Extraction and cleaning equipment, Soxhlet extraction and cleaning equipment, high-temperature and high-pressure extraction and cleaning equipment, microwave extraction and cleaning equipment, supercritical extraction and cleaning equipment, cleaning equipment using hydrofluoric acid, hydrochloric acid, sulfuric acid, ozone water, etc., steppers, coating and developing machines, chemical mechanical polishing (CMP) equipment, excimer laser exposure machines, chemical piping, gas piping, plasma treatment equipment (e.g., nitrogen trifluoride (NF3) plasma treatment, oxygen plasma treatment, fluorine plasma treatment, etc.), heat treatment film forming equipment, wafer transport machines, wafer cleaning equipment, silicon wafer cleaning equipment, silicon wafer processing equipment, reduced pressure CVD (LPCVD) equipment, lamp annealing equipment, reflow equipment, etc.

[0329] In semiconductor-related fields, examples of its applications include various sealing materials such as gate valves, quartz windows, chambers, chamber covers, gates, bell jars, couplings, pump O-rings, and gaskets; various sealing materials, hoses, and tubes such as O-rings for resist developers and strippers; linings and coatings for resist developers, strippers, wafer cleaning solutions, and wet etching tanks; pump diaphragms; rollers for wafer transport; hoses for wafer cleaning solutions; sealants for cleanrooms and other cleaning equipment; sealing materials for semiconductor manufacturing equipment and wafer storage facilities; and diaphragms for chemical delivery in semiconductor manufacturing processes.

[0330] Examples of its applications in the semiconductor industry include: tubing for wafer cleaning solutions, resist developer tanks, stripper tanks, wafer cleaning solution tanks, liner / coating for wet etching tanks, diaphragms for pumps, rollers for wafer transport, gate valves, quartz windows, chambers, chamber covers, gates, bell jars, couplings, O-rings / gaskets for pumps, O-rings for resist developers / strippers, hoses / tubes, sealants for cleanrooms and other cleaning equipment, sealing materials for semiconductor manufacturing equipment / wafer storage facilities, and diaphragms for chemical delivery in semiconductor manufacturing processes.

[0331] The aforementioned crosslinked rubber articles can be manufactured by crosslinking the solid composition of the present invention.

[0332] As a crosslinking method, for example, methods of adding crosslinking agents for mixing or molding can be cited.

[0333] Specific examples of crosslinking agents include organic peroxides, polyols, amines, and triazines. Organic peroxides are preferred from the perspectives of high productivity, heat resistance, and chemical resistance of crosslinked rubber articles.

[0334] Specific examples of organic peroxides include dialkyl peroxides, α,α'-bis(tert-butylperoxide)-p-diisopropylbenzene, α,α'-bis(tert-butylperoxide)-m-diisopropylbenzene, benzoyl peroxide, tert-butylperoxide, and 2,5-dimethyl-2,5-bis(benzoyl peroxide)hexane.

[0335] Specific examples of dialkyl peroxides include 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 2,5-dimethylhexane-2,5-dihydroxyperoxide, tert-butyl cumene peroxide, dicumene peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-bis(tert-butylperoxy)-3-hexyne, tert-butylperoxymaleic acid, and tert-butylperoxyisopropyl carbonate.

[0336] In the manufacture of crosslinked rubber articles, other components besides crosslinking agents may also be used. Examples of such other components include catalysts, crosslinking aids, acid scavengers, fillers and reinforcing materials, scorch delay agents, crown ethers, and release agents.

[0337] Examples of the molding methods mentioned above include injection molding, extrusion molding, co-extrusion molding, blow molding, compression molding, blow molding, transfer molding, and calendering.

[0338] Example

[0339] The present invention will now be described in detail with examples. Examples 1-3 are embodiments, and Examples 4-5 are comparative examples. However, the present invention is not limited to these examples.

[0340] The average particle size of the particles in the aqueous dispersion was measured using the aqueous dispersions described below as samples, and the measurement was performed using a dynamic light scattering particle size analyzer (Otsuka Electronics Co., Ltd., ELSZ).

[0341] [Preparation of solid compositions]

[0342] <Manufacturing of Raw Material Solution A>

[0343] Ultrapure water (1130g), 30% ammonia solution (30mg), PMVE (72g), and TFE (14g) were charged into a 2.2L stainless steel pressure reactor equipped with anchor blades. The mixture was heated to 90°C while stirring at 600 rpm. Then, ammonium persulfate solution (5.0% by mass, 30cc) was added to initiate polymerization. Since the pressure inside the reactor decreased as polymerization began, TFE was added to maintain a constant pressure. After adding 4g of TFE, the reactor was cooled to terminate the polymerization reaction. The total monomers added before polymerization began were 14g TFE and 72g PMVE. The total monomers added after polymerization began were 4g TFE and 0g PMVE. The total amount of TFE added was 18g, and the total amount of PMVE added was 72g. After recovering the residual gas in the reactor, the liquid was extracted. This liquid was used as feedstock A.

[0344] After the raw material liquid A was frozen and coagulated, it was filtered and separated. The obtained fluoropolymer 1A was analyzed by NMR, and the result was PAVE unit / TFE unit = 34 / 66 (molar ratio).

[0345] <Manufacturing of Raw Material Solution B>

[0346] 1000g of HPR4002Cl (a styrene-based gel-type strong basic anion exchange resin manufactured by DuPont) was mixed with 2000g of 8% sodium hydroxide aqueous solution, and stirred for 60 minutes to exchange chloride ions in the resin for hydroxide ions. It should be noted that the total exchange capacity of the above anion exchange resin is 1.25 eq / L-Resin, and the average diameter is 0.50~0.65 mm. 200g of the obtained anion exchange resin was added to the above feed solution A, and stirring was started. After stirring for 150 minutes, the feed solution and ion exchange resin were separated by filtration. Next, 50g of AmberLite (registered trademark) HPR650H (a cation exchange resin manufactured by DuPont) was added to the filtrate. After stirring for 60 minutes, the feed solution and ion exchange resin were separated by filtration to obtain feed solution B. In feed solution B, fluoropolymer 1A particles are dispersed in an aqueous medium, and the content of fluoropolymer 1A is 0.6% of the total mass of feed solution B.

[0347] <Example 1>

[0348] Feed solution B (1000g) and ultrapure water (175g) were added to a 2.2L stainless steel pressure reactor equipped with anchor blades to obtain aqueous dispersion 1-1. It should be noted that the content of fluoropolymer 1A is 0.4% by mass relative to the total mass of aqueous dispersion 1-1.

[0349] Add 1.25 g of perfluoro-1,4-diiodobutane, 90 g of PMVE, and 14 g of TFE to aqueous dispersion 1-1, and heat to 80 °C while stirring at 600 rpm. Inject TFE and PMVE until the reactor pressure reaches 1.5 MPa (gauge pressure), then add ammonium persulfate aqueous solution (APS aqueous solution, 1.0% by mass, 20 ml, ammonium persulfate 0.2 g) to begin polymerization. Since the pressure inside the reactor decreases as polymerization begins, TFE / PMVE is injected at a 65 / 35 molar ratio to maintain a constant pressure. After injecting 256 g of TFE and 217 g of PMVE, the reactor is cooled to end the polymerization reaction. The polymerization time is 380 minutes. The total monomers added before polymerization begins are 14 g of TFE and 90 g of PMVE. The total monomers added after polymerization begins are 256 g of TFE and 217 g of PMVE. The total amount of TFE added is 270g, and the total amount of PMVE added is 307g.

[0350] The aqueous dispersion 1-1 described above substantially does not contain water-soluble emulsifiers. Specifically, the content of emulsifier A and the compounds shown in formulas (S1) to (S4) described later is determined by the following method. It should be noted that, in the manufacture of aqueous dispersion 1-1, emulsifiers other than emulsifier A and the compounds shown in formulas (S1) to (S4) are not generated from the components used to manufacture aqueous dispersion 1-1, nor are they used, and therefore are not included in aqueous dispersion 1-1.

[0351] To determine the solid content of aqueous dispersion 1-1, weigh an amount equivalent to 0.05 g of solid content into a 100 mL threaded tube. Then, add water and methanol to the weighed aqueous dispersion 1-1 in a manner that yields 40 g of water / methanol = 50 / 50 vol%. Shake thoroughly until coagulation occurs. Remove the solid content, centrifuge the liquid phase at 4000 rpm for 1 hour, and extract the supernatant. The determination is performed using the same method as described below for the determination of emulsifier content, except for the sample preparation method. The result is that the content of any of the compounds represented by formulas (S1) to (S4) is also below the quantitation limit relative to aqueous dispersion 1-1.

[0352] After recovering the residual gas in the reactor, the liquid is extracted. This liquid is designated as aqueous dispersion 2-1. Aqueous dispersion 2-1 is a dispersion containing fluoropolymer particles (average particle size 92.7 nm) dispersed in an aqueous medium, with a solids concentration of 20.5% by mass.

[0353] The above aqueous dispersion 2-1 was placed in a cylindrical tank and stirred at 5 m / s for 150 minutes using a disc turbine blade with 8 blades evenly spaced at right angles on the outer circumference of the disc. The solids were then filtered to separate and recovered. The recovered solids were washed with 2,000 g of ultrapure water at 40°C and dried to obtain a rubbery solid composition 1. It should be noted that the circumferential speed (m / s) of the stirring is the speed of the blades at the tip of the stirring blades.

[0354] The fluoropolymer contained in the obtained solid composition 1 was analyzed by NMR, and the result was that the PAVE unit / TFE unit ratio was 34 / 66 (molar ratio).

[0355] <Preparation of Raw Material Solution C>

[0356] Except for appropriate changes in the dosage of each component, the fluoropolymer 1C was polymerized using the same steps as the preparation of feedstock A, and this liquid was used as feedstock C. After the feedstock C was frozen and coagulated, it was filtered and separated. The obtained fluoropolymer 1C was analyzed by NMR, and the result was PAVE unit / TFE unit = 32 / 68 (molar ratio).

[0357] <Manufacturing of Raw Material Solution D>

[0358] Except that feedstock solution C is used instead of feedstock solution A, feedstock solution D is prepared following the same steps as feedstock solution B. In feedstock solution D, fluoropolymer 1C particles are dispersed in an aqueous medium, and the content of fluoropolymer 1C is 0.6% by mass relative to the total mass of feedstock solution D.

[0359] <Example 2>

[0360] Feed solution D (1000 g) and ultrapure water (175 g) were added to a 2.2 L stainless steel pressure reactor equipped with anchor blades to obtain aqueous dispersion 1-2. It should be noted that the content of fluoropolymer 1C is 0.4% by mass relative to the total mass of aqueous dispersion 1-2. Aqueous dispersion 1-2 is substantially free of water-soluble emulsifiers. The emulsifier content was confirmed using the same method as for aqueous dispersion 1-1 described above.

[0361] PMVE (72g), perfluoro-1,4-diiodobutane (2.0g), and TFE (14g) were added to aqueous dispersion 1-2, and the mixture was heated to 80°C while stirring at 600 rpm. TFE and PMVE were added until the reactor pressure reached 1.5 MPa [gauge]. APS aqueous solution (0.5% by mass, 16ml, and ammonium persulfate, 0.08g) was added to initiate polymerization. Since the pressure inside the reactor decreased as polymerization began, TFE / PMVE was added at a molar ratio of 65 / 35 to maintain a constant pressure. After adding 256g of TFE and 217g of PMVE, the reactor was cooled to terminate the polymerization reaction. The polymerization time was 290 minutes. The total monomers added before polymerization started were 14g of TFE and 72g of PMVE. The total monomers added after polymerization started were 256g of TFE and 217g of PMVE. The total amount of TFE added is 270g, and the total amount of PMVE added is 289g.

[0362] After recovering the residual gas in the reactor, the liquid is extracted. This liquid is designated as aqueous dispersion 2-2. Aqueous dispersion 2-2 is a dispersion containing fluoropolymer particles (average particle size 140.3 nm) dispersed in an aqueous medium, with a solids concentration of 28.6% by mass.

[0363] The above aqueous dispersion 2-2 was stirred with a paddle at 10 m / s for 150 minutes, then filtered to separate the solids and recovered. The recovered solids were washed with 2,000 g of ultrapure water at 40 °C and dried to obtain a rubbery solid composition 2.

[0364] The fluoropolymer contained in the obtained solid composition 2 was analyzed by NMR, and the result was that the PAVE unit / TFE unit ratio was 35 / 65 (molar ratio).

[0365] <Example 3>

[0366] Feed solution D (1000g) and ultrapure water (175g) were added to a 2.2L stainless steel pressure reactor equipped with anchor blades to obtain aqueous dispersion 1-3. It should be noted that the content of fluoropolymer 1C is 0.4% by mass relative to the total mass of aqueous dispersion 1-3. Aqueous dispersion 1-3 is substantially free of water-soluble emulsifiers. The emulsifier content was confirmed using the same method as for aqueous dispersion 1-1 described above.

[0367] PMVE (72g) and TFE (14g) were added to aqueous dispersions 1-3, and the mixture was heated to 80°C while stirring at 600 rpm. TFE and PMVE were added until the reactor pressure reached 1.5 MPa [gauge]. APS aqueous solution (0.5% by mass, 16ml, ammonium persulfate, 0.08g) was added to initiate polymerization. Since the pressure inside the reactor decreased as polymerization began, TFE / PMVE was added at a molar ratio of 65 / 35 to maintain a constant pressure. After adding 6g of TFE, perfluoro1,4-diiodobutane (2.0g) was added. After adding 256g of TFE and 217g of PMVE, the reactor was cooled to end the polymerization reaction. The polymerization time was 290 minutes. The total monomers added before polymerization started were 14g TFE and 72g PMVE. The total monomers added after polymerization started were 256g TFE and 217g PMVE. The total amount of TFE added is 270g, and the total amount of PMVE added is 289g.

[0368] After recovering the residual gas in the reactor, the liquid is extracted. This liquid is designated as aqueous dispersion 2-3. Aqueous dispersion 2-3 is a dispersion containing fluoropolymer particles (average particle size 96 nm) dispersed in an aqueous medium, with a solids concentration of 27.6% by mass.

[0369] The above aqueous dispersion 2-3 was stirred with 6 turbine blades at 30 m / s for 150 minutes, then filtered to separate the solids and recovered. The recovered solids were washed with 2,000 g of ultrapure water at 25°C and dried to obtain a rubbery solid composition 3.

[0370] The fluoropolymer contained in the obtained solid composition 3 was analyzed by NMR, and the result was that the ratio of PAVE units to TFE units was 34 / 65 (molar ratio).

[0371] <Example 4>

[0372] After degassing a 2.2L stainless steel pressure reactor equipped with anchor blades, 1004g of ultrapure water, 80.1g of a 30% by mass solution of C2F5OCF2CF2OCF2COONH4 (emulsifier A) as an emulsifier, and 10.49g of a 5% by mass aqueous solution of disodium hydrogen phosphate·12-hydrate were added to purge the gas phase with nitrogen. While stirring at 600rpm using anchor blades, 72g of PMVE and 14g of TFE were added to the container, and the internal temperature was raised to 80°C. Then, 20ml of APS aqueous solution (1.0% by mass) was added to initiate polymerization. Since the pressure inside the reactor decreased as polymerization began, TFE / PMVE was added at a 65 / 35 molar ratio to maintain a constant pressure of 1.2MPa. After adding 160g of TFE and 133g of PMVE, the reactor was cooled to terminate the polymerization reaction. The aggregation time was 262 minutes.

[0373] After recovering the residual gas in the reactor, the liquid is extracted. This liquid is designated as aqueous dispersion 4. Aqueous dispersion 4 is a dispersion containing fluoropolymer particles (average particle size 84 nm) dispersed in an aqueous medium, with a solids concentration of 21.1% by mass.

[0374] An aqueous aluminum sulfate solution (5%, 2,000 g) was added to the above aqueous dispersion 4, and the coagulant was separated by filtration and recovered. The recovered coagulant was washed with 2,000 g of ultrapure water at 40°C, and the solids were separated by filtration and recovered. The recovered solids were dried to obtain a rubbery solid composition 4.

[0375] The fluoropolymer contained in the obtained solid composition 4 was analyzed by NMR, and the result was that the PAVE unit / TFE unit ratio was 35 / 65 (molar ratio).

[0376] <Example 5>

[0377] After degassing a 2.2L stainless steel pressure reactor equipped with anchor blades, 1004g of ultrapure water, 80.1g of a 30% by mass solution of C2F5OCF2CF2OCF2COONH4 (emulsifier A) as an emulsifier, and 10.49g of a 5% by mass aqueous solution of disodium hydrogen phosphate·12-hydrate were added to purge the gas phase with nitrogen. While stirring at 600 rpm using anchor blades, 72g of PMVE and 14g of TFE were added to the reactor, and the internal temperature was raised to 80°C. Then, 20ml of 1.0% by mass APS aqueous solution and 0.1g of ammonium persulfate were added to initiate polymerization. Since the pressure inside the reactor decreased as polymerization began, TFE / PMVE was added at a 65 / 35 molar ratio to maintain a constant pressure of 1.2MPa. After injecting 160g of TFE and 133g of PMVE, the reactor was cooled to end the polymerization reaction. The polymerization time was 280 minutes.

[0378] After recovering the residual gas in the reactor, the liquid is extracted. This liquid is designated as aqueous dispersion 5. Aqueous dispersion 5 is a dispersion containing 1g of fluoropolymer particles (average particle size 98.6nm) dispersed in an aqueous medium, with a solid content concentration of 20.1% by mass.

[0379] The above aqueous dispersion 5 was added to an aqueous nitric acid solution (3% by mass, 2,500 g) and stirred. The solids were then separated by filtration and recovered. The recovered solids were washed with 2,000 g of ultrapure water at 60°C and dried to obtain a rubbery solid composition 5.

[0380] The fluoropolymer contained in the obtained solid composition 5 was analyzed by NMR, and the result was that the PAVE unit / TFE unit ratio was 35 / 65 (molar ratio).

[0381] [Measurement and Evaluation Methods]

[0382] The various measurement and evaluation methods are described below.

[0383] <Requirement X>

[0384] Weigh each solid composition obtained in the examples shown in the table below, and measure the pH at 23°C using a benchtop pH meter (HORIBA, LAQUA) for the mixture obtained after mixing with water adjusted to 23°C and pH 6 for 24 hours in the amounts shown in the table below (5 times the mass of the solid composition).

[0385] Crosslinking rate t 50 and t 90 >

[0386] Using the solid compositions obtained in each example, a crosslinking rate evaluation composition with the components shown in Table 1 below was prepared and mixed using two rollers at 23°C for 10 minutes. After mixing, the gap between the two rollers was adjusted to obtain a crosslinking rate evaluation sheet with a thickness of 3 mm.

[0387] The components and abbreviations are described in the table below.

[0388] •CB: MT Carbon N990, manufactured by Vanderbilt Corporation.

[0389] • Crosslinking aid: TAIC-WH60, manufactured by Mitsubishi Chemical, 60% triallyl isocyanurate diluted with silica

[0390] • Crosslinking agent: PERHEXA 25B, Nippon Oil, 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane

[0391] • Release agent: NONSOUL SN-1, manufactured by Nippon Oil, sodium stearate

[0392] [Table 1]

[0393]

[0394] The crosslinking rate evaluation sheet was cut into 10g pieces to obtain cut sheet material. The cut sheet material was clamped from both sides of the main surface using two sheets of polyester film (ALFA Technologies, PART#F0311-S, 130mm×130mm×24μm) to obtain the test sample. For the test sample, the torque (dNm) was measured under the following conditions: measuring apparatus: PREMIER RPA (Alpha Technologies), mold shape: D0380, 150℃, 12 minutes, 100 cpm, Angle: 3.00deg. The minimum torque value was set to 0%, and the maximum torque value was set to 100%. The processing time for obtaining 50% of the torque value was set to t. 50 The processing time for 90% of the torque value will be set to t. 90 .

[0395] <Emulsifier content>

[0396] (Preparation of samples for determination)

[0397] The solid compositions obtained in the examples described below were cryogenically pulverized using a Freezer Mill 6775 cryogenic pulverizer (manufactured by SPEX) under the following conditions. Before cryogenic pulverization, 10% by mass of butylated hydroxytoluene (BHT) relative to the total mass of the solid composition was added to obtain a pulverized powder. The cryogenic pulverization conditions were set as follows: solid composition: 3 g, BHT: 0.3 g, running time: 5 mins, rate: 15 cps, cycle time: 3.

[0398] Add 5 mL of methanol to 0.25 g of the obtained pulverized powder, sonicate at 50 °C for 2 hours, and centrifuge (5000 rpm, 5 minutes) to allow the fluoropolymers to settle. Use the supernatant as the extract. Perform LC / MS / MS analysis on the extract. For emulsifiers and hydrocarbon emulsifiers containing fluorine atoms in the extract, use liquid chromatography-mass spectrometry (LC-MS). The instrument configuration and LC-MS conditions are shown in Table 1. Prepare aqueous solutions with known concentrations of emulsifiers and hydrocarbon emulsifiers at five or more levels, and perform LC / MS analysis on each concentration. Plot the relationship between the concentration and the area of ​​the region relative to the concentration to construct a calibration curve. Using the calibration curve, convert the area of ​​the LC / MS chromatogram of emulsifiers and hydrocarbon emulsifiers containing fluorine atoms in the extract to the concentration of emulsifiers and hydrocarbon emulsifiers containing fluorine atoms.

[0399] [Table 2]

[0400]

[0401] MRM determination parameters are appropriately selected based on the structure of the fluorine-containing emulsifier and hydrocarbon emulsifier being measured. MRM parameters can be obtained from literature or calculated using an LC-MS apparatus. The specific steps for determining MRM parameters using an LC-MS apparatus are as follows: Using an LC / MS apparatus (Shimadzu Corporation, LCMS-8060NX), product ion exploration is performed, and the molecular weights of the fluorine-containing emulsifier and hydrocarbon emulsifier being measured are input. Precursor ion, precursor adjustment, voltage optimization, and product m / z optimization are then performed. The calculated MRM determination parameters are then used. As an example, the MRM determination parameters for compounds (S2) and (S4) that are fluorine-containing emulsifiers are shown in the table. It should be noted that in formulas (S2) and (S4), MS represents hydrogen atom, metal atom, NR4 (R can be the same or different, and can be a hydrogen atom or an organic group with 1 to 10 carbon atoms), optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium.

[0402] F-(CF2)n1-COOMS (S2)

[0403] F-(CF2)n2-SO3MS (S4)

[0404] Where n1 is an integer from 3 to 17, and n2 is an integer from 4 to 12.

[0405] [Table 3]

[0406]

[0407] [Table 4]

[0408]

[0409] (Quantitative analysis of emulsifiers and hydrocarbon emulsifiers containing fluorine atoms in the solid composition)

[0410] Specifically, firstly, methanol standard solutions of emulsifiers with known concentrations of fluorine atoms and hydrocarbon emulsifiers with concentrations of 1~180 ng / g were prepared at five levels. a was calculated by using a first approximation based on the sample concentration and peak integral value of each sample, and then by equation (A1-1).

[0411] A = a × X (A1-1)

[0412] A: Peak area of ​​each emulsifier; X: Concentration of each emulsifier (ng / g)

[0413] Next, the amount of emulsifier contained in the extract is calculated using equation (A1-2). It should be noted that 'a' in equation (A1-2) refers to the 'a' obtained from equation (A1-1) above.

[0414] XCm=ACm / a (A1-2)

[0415] XCm: Emulsifier content in each extract (ng / g)

[0416] ACm: Peak area of ​​emulsifier in each extract

[0417] It should be noted that the quantitative limit in this assay is 1 ng / g.

[0418] In a solid composition, the content of emulsifier (ZCm) relative to the total mass of the solid composition is determined by the following formula (A1-3).

[0419] ZCm=XCm×ρ1×La / W1 (A1-3)

[0420] ZCm: The content of emulsifier in the solid composition.

[0421] ρ1: Density of the extraction solvent (methanol in each example)

[0422] La: Volume of extraction solvent (5 mL in each example)

[0423] W1: Mass of sample used in extraction (2.5 g of solid composition in each example)

[0424] <Quantitative methods for formulas (S1) and (S3) contained in solid compositions>

[0425] The solid compositions obtained in the examples described below were cryogenically pulverized using a Freezer Mill 6775 cryogenic pulverizer (manufactured by SPEX) under the following conditions. Before cryogenic pulverization, 10% by mass of butylated hydroxytoluene (BHT) relative to the total mass of the solid composition was added to obtain a pulverized powder. The cryogenic pulverization conditions were set as follows: solid composition: 3 g, BHT: 0.3 g, running time: 5 minutes, rate: 15 cps, cycle: 3.

[0426] Add 5 mL of methanol to 2.5 g of the obtained pulverized powder, sonicate at 50 °C for 2 hours, centrifuge (5000 rpm, 5 minutes) to allow each fluoropolymer to settle, and use the supernatant as the extract.

[0427] The obtained extract was analyzed by LC / MS / MS. For emulsifiers containing fluorine atoms in the extract, liquid chromatography-mass spectrometry (LC-MS) was used for determination. The instrument configuration and LC-MS determination conditions are as described above. Methanol solutions with concentrations of known fluorine-containing emulsifiers were prepared at five or more levels, and LC / MS analysis was performed on each methanol solution. The relationship between the concentration and the area of ​​the region relative to its concentration was plotted, and a calibration curve was drawn. Using the calibration curve, the area of ​​the LC / MS chromatogram of the emulsifier containing fluorine atoms in the extract was converted to the concentration of the emulsifier containing fluorine atoms.

[0428] The content of compounds represented by formula (S1) in each extract was determined by converting compounds with n1=3~13 in formula (S1) to perfluorocarboxylic acids with the same number of carbon atoms (formula (S2)). Similarly, the content of compounds represented by formula (S3) in each extract was determined by converting compounds with n2=4~10 in formula (S3) to perfluorosulfonic acids with the same number of carbon atoms (formula (S4)). The MRM parameters for formulas (S1) and (S3) are shown in Tables 5 and 6.

[0429] Specifically, firstly, methanol standard solutions of perfluorocarboxylic acid and perfluorosulfonic acid with known concentrations of 1–180 ng / g were prepared at five levels. Then, a and a' were calculated using equations (A2-1) and (A2-1') based on the sample concentrations and peak integral values ​​of each sample and the first approximation.

[0430] A = a × X (A² - 1)

[0431] A: Peak area of ​​perfluorocarboxylic acids; X: Concentration of perfluorocarboxylic acids (ng / g)

[0432] A' = a' × X' (A² - 1')

[0433] A': Peak area of ​​perfluorosulfonic acid, X': Concentration of perfluorosulfonic acid (ng / g)

[0434] [Table 5]

[0435]

[0436] [Table 6]

[0437]

[0438] Specifically, firstly, using the liquid chromatography-mass spectrometry system described above, the peak areas of the compounds represented by formulas (S1) and (S3) contained in each of the above extracts are determined.

[0439] Next, the contents of the compounds shown in formula (S1) and formula (S3) are calculated using formulas (A2-2) and (A2-2'), respectively. It should be noted that 'a' in formula (A2-2) refers to 'a' obtained from formula (A2-1) above, and 'a' in formula (A2-2') refers to 'a' obtained from formula (A2-1') above.

[0440] XCm=ACm / a (A2-2)

[0441] XCm: The content (ng / g) of the compound represented by formula (S1) with the number of carbon atoms (n+1) in each extract.

[0442] ACm: Peak area of ​​the compound represented by formula (S1) with the number of carbon atoms (n+1) in each extract.

[0443] XCm'=ACm' / a' (A2-2')

[0444] XCm': The content (ng / g) of the compound represented by formula (S3) with the number of carbon atoms n in each extract.

[0445] ACm': Peak area of ​​the compound represented by formula (S3) with the number of carbon atoms n in each extract.

[0446] It should be noted that the quantitative limit in this assay is 1 ng / g.

[0447] In a solid, the content (ZCm) of formula (S1) relative to the total mass of the solid is obtained by formula (A2-3).

[0448] ZCm=XCm×ρ1×La / W1 (A2-3)

[0449] ZCm: The content of the compound represented by formula (S1) with the number of carbon atoms (n+1) in the solid.

[0450] ρ1: Density of the extraction solvent (methanol in each example)

[0451] La: Volume of extraction solvent (5 mL in each example)

[0452] W1: Mass of sample used in extraction (2.5g of solids in each example)

[0453] In solid matter, the content (ZCm') of formula (S3) relative to the total mass of solid matter is obtained by formula (A2-4).

[0454] ZCm'=XCm'×ρ1×La / W1 (A2-4)

[0455] ZCm': The content of the compound represented by formula (S3) with the number of carbon atoms n in the solid.

[0456] ρ1: Density of the extraction solvent (methanol in each example)

[0457] La: Volume of extraction solvent (5 mL in each example)

[0458] W1: Mass of sample used in extraction (2.5g of solids in each example)

[0459] The emulsifier content described in Examples 1 to 5 respectively represents the total content of emulsifier A and the total content of each compound shown in formulas (S1) to (S4) above, relative to the total mass of each solid composition. (Examples 1 to 3 do not use emulsifier A and essentially represent the total content of each compound shown in formulas (S1) to (S4) above.)

[0460] <Metal content>

[0461] Each solid composition obtained in each example was placed in a platinum crucible, ashed in a high-temperature electric furnace, and then treated with sulfuric acid fumes. Then, for the liquid dissolved in dilute nitric acid, the contents of 29 metallic elements (Fe, Na, K, Li, Be, Mg, Al, Ca, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Rb, Sr, Zr, Mo, Ag, Cd, In, Sn, Cs, Ba, Pb, Bi) determined by absolute calibration curve analysis were calculated using an inductively coupled plasma mass spectrometry (ICP-MS 7500cs) instrument, and their total contents were calculated.

[0462] In the table below, the metal content represents the total content of the above 29 metallic elements.

[0463] <Storage Modulus G'>

[0464] As the measuring device, the rubber processability analysis apparatus "PREMIER RPA (manufactured by Alpha Technologies, mold shape: D0380)" was used.

[0465] The solid compositions obtained in each example were mixed using two rollers at room temperature (23°C) for 10 minutes to produce a sheet with a thickness of 3 mm. The thickness of the sheet was adjusted by adjusting the gap between the two rollers.

[0466] The obtained sheet was cut into pieces weighing approximately 10g each, yielding cut pieces. These cut pieces were then clamped between two sheets of polyester film (ALFA Technologies PART#F0311-S, 130mm × 130mm × 24μm) to obtain the sample for testing. The sample was then placed on the mold of the aforementioned testing apparatus. The mold temperature was preset to 100°C.

[0467] Next, the sample was held at 100℃, 30 cpm, and 0.2 degrees for 2 minutes. Then, the amplitude angle was set to 0.5 degrees, and the frequency was increased to 10 cpm, 20 cpm, and 50 cpm, and the storage modulus was measured. The storage modulus at the current frequency of 50 cpm and 100℃ was taken as the storage modulus G' of the sample (unit: kPa).

[0468] [Table 7]

[0469]

[0470] The evaluation results of Examples 1 to 3 show that, according to the manufacturing method of the present invention, since it is substantially free of emulsifiers and coagulants that reduce the vulcanization rate, it is possible to manufacture a solid composition with excellent crosslinking rate.

[0471] Examples 4 and 5 are manufacturing methods that use a coagulant when polymerizing a solid composition using an aqueous solution containing an emulsifier. The resulting solid composition contains an emulsifier, and the crosslinking rate of the resulting solid composition deteriorates.

[0472] It should be noted that the entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2023-222139, filed on December 28, 2023, are incorporated herein as a disclosure of the specification of this invention.

Claims

1. A method for manufacturing a solid composition, wherein, In an aqueous dispersion containing a first fluoropolymer and an aqueous medium that is substantially free of water-soluble emulsifiers, a monomer containing tetrafluoroethylene and a perfluoro(alkyl vinyl ether) is polymerized. The resulting aqueous dispersion containing a second fluoropolymer is then subjected to stirring treatment, and the solids obtained after the stirring treatment are recovered to obtain a solid composition. The first fluoropolymer comprises tetrafluoroethylene-based units and perfluoro(alkyl vinyl ether)-based units. In the first fluoropolymer, the perfluoro(alkyl vinyl ether)-based units comprise 5 to 80 mol% relative to the total of the tetrafluoroethylene-based units and the perfluoro(alkyl vinyl ether)-based units. In the second fluoropolymer, the perfluoro(alkyl vinyl ether)-based units comprise 15-95 mol% relative to the total of the tetrafluoroethylene-based units and the perfluoro(alkyl vinyl ether)-based units. Before the polymerization of the monomer begins, the content of the first fluoropolymer is 0.01 to 4.0% by mass relative to the total mass of the aqueous dispersion.

2. The method for manufacturing the solid composition according to claim 1, wherein, The solid composition has a storage modulus of 300 kPa or more at 100°C.

3. The method for manufacturing the solid composition according to claim 1 or 2, wherein, The solid composition does not contain emulsifiers; Alternatively, if the solid composition contains the emulsifier, the total content of the emulsifier relative to the total mass of the solid composition is less than 500 ppb.

4. The method for manufacturing the solid composition according to claim 1 or 2, wherein, The total metal content of the solid composition is less than 20 ppm by mass relative to the total mass of the solid composition.

5. The method for manufacturing the solid composition according to claim 1 or 2, wherein, In the second fluoropolymer, the tetrafluoroethylene-based units comprise 35 to 80 mol% relative to all units; the perfluoro (alkyl vinyl ether)-based units comprise 20 to 60 mol%.

6. The method for manufacturing the solid composition according to claim 1 or 2, wherein, The second fluoropolymer comprises at least one selected from the group consisting of polymerizable unsaturated bonds, chlorine atoms, bromine atoms, iodine atoms, and nitrile groups.

7. A method for manufacturing a solid composition according to claim 1 or 2, comprising a step of cleaning the solid composition.

8. A solid composition comprising: a fluoropolymer containing tetrafluoroethylene-based units and perfluoro(alkyl vinyl ether)-based units, The solid composition is substantially free of emulsifiers and satisfies requirement X. Requirement X: In a mixture obtained by mixing the solid composition and water at pH 6 such that the mass of the water is 5 times the mass of the solid composition, the pH of the mixture at 23°C is greater than or equal to 4 24 hours after the start of mixing.

9. The solid composition according to claim 8 is substantially free of coagulants.

10. A crosslinked rubber article formed by crosslinking the solid composition of claim 8 or 9.

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