Process for producing fluoropolymer, fluoropolymer aqueous dispersion, and polymer composition

Abstract

Provided is a method for producing a fluoropolymer without using an emulsifier even when using a water-based medium with a small environmental load. A method for producing a fluoropolymer, wherein at least one fluoromonomer selected from the group consisting of tetrafluoroethylene, chlorotrifluoroethylene, and vinylidene fluoride is polymerized in the presence of a specific polymer containing at least one unit selected from the group consisting of a unit based on a compound represented by the following formula (1) and a unit based on a compound represented by the following formula (2) in a water-based medium to produce a fluoropolymer (wherein, in the case of polymerizing the tetrafluoroethylene, the tetrafluoroethylene is polymerized under the condition that the content of the unit based on tetrafluoroethylene in the fluoropolymer is less than 99 mass% relative to all units of the fluoropolymer). Formula (1) CXY=CR 1 -COO-(L-O) n -R 2 Formula (2) CXY=CR 3 -(O) m -CH2-Z-R 4

Description

Technical Field

[0001] This invention relates to a method for manufacturing fluoropolymers, aqueous dispersions of fluoropolymers, and polymer compositions. Background Technology

[0002] Fluoropolymers such as ethylene / tetrafluoroethylene copolymers or tetrafluoroethylene / perfluoroalkyl vinyl ether copolymers have excellent heat resistance, chemical resistance, flame retardancy, and weather resistance, and are therefore used in various industrial fields.

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

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2007 / 046377 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] Since Patent Document 1 uses an aqueous medium, it has a low environmental impact. However, since a large amount of emulsifier, which is an essential component, remains in the aqueous dispersion obtained by polymerization, the emulsifier must be removed depending on the application.

[0009] The objective of this invention is to provide a method for manufacturing fluoropolymers that does not require emulsifiers, even when using aqueous media with low environmental impact.

[0010] Furthermore, the subject of this invention is also to provide an aqueous dispersion of a fluoropolymer and a polymer composition.

[0011] Technical solutions adopted to solve technical problems

[0012] Through in-depth research, the inventors have discovered that the above-mentioned technical problems can be solved by the following configuration.

[0013] [1] A method for manufacturing a fluoropolymer, wherein, in an aqueous medium, in the presence of a specific polymer comprising at least one unit selected from tetrafluoroethylene, trichlorofluoroethylene, and vinylidene fluoride, a fluoropolymer is manufactured by polymerizing at least one fluorinated monomer selected from tetrafluoroethylene, trichlorofluoroethylene, and vinylidene fluoride (wherein, in the case of polymerizing the tetrafluoroethylene, the tetrafluoroethylene is copolymerized under conditions where the content of the tetrafluoroethylene-based unit in the fluoropolymer is less than 99% by mass relative to all units of the fluoropolymer):

[0014] Equation (1): CXY = CR 1 -COO-(LO) n -R 2

[0015] Equation (2): CXY = CR 3 -(O) m -CH2-ZR 4

[0016] The symbols in equations (1) and (2) have the following meanings:

[0017] X and Y independently represent hydrogen atoms, halogen atoms, or methyl groups.

[0018] R 1 Indicates a hydrogen atom, a halogen atom, or an alkyl group having 1 to 3 carbon atoms.

[0019] R 2 The group represents an alkyl group, an alkyl group in which at least one -CH2- is replaced by -CO-, or a group represented by formula (3) below.

[0020] R 3 It represents hydrogen atoms, halogen atoms, alkyl groups having 1 to 3 carbon atoms, or -CO-OCH3.

[0021] R 4 Indicates alkyl group,

[0022] L indicates alkylene.

[0023] Z represents -CO-O-* or -O-CO-*, where * indicates that it is related to R. 4 The bonding position,

[0024] m represents 0 or 1, and n represents an integer greater than or equal to 1.

[0025] Equation (3): -CO-CR 1 =CXY

[0026] In equation (3), X, Y and R 1 respectively with X, Y and R in equation (1) 1 The definitions are the same.

[0027] [2] The manufacturing method as described in [1], wherein the amount of the specific polymer present is 0.0001 to 1.0 parts by mass relative to 100 parts by mass of the aqueous medium.

[0028] [3] A method for manufacturing a fluoropolymer, wherein at least one specific compound selected from compounds represented by formula (1) and formula (2) is polymerized in an aqueous medium to obtain an aqueous medium containing the specific polymer, and then, in the aqueous medium containing the specific polymer, at least one fluorinated monomer selected from tetrafluoroethylene, trichlorofluoroethylene, and vinylidene fluoride is polymerized to manufacture the fluoropolymer (wherein, in the case of polymerizing the tetrafluoroethylene, the tetrafluoroethylene is copolymerized under the condition that the content of tetrafluoroethylene-based units in the fluoropolymer is less than 99% by mass relative to all units of the fluoropolymer):

[0029] Equation (1): CXY = CR 1 -COO-(LO) n -R 2

[0030] Equation (2): CXY = CR 3 -(O) m -CH2-ZR 4

[0031] The symbols in equations (1) and (2) have the following meanings:

[0032] X and Y independently represent hydrogen atoms, halogen atoms, or methyl groups.

[0033] R 1 Indicates a hydrogen atom, a halogen atom, or an alkyl group having 1 to 3 carbon atoms.

[0034] R 2 The group represents an alkyl group, an alkyl group in which at least one -CH2- is replaced by -CO-, or a group represented by formula (3) below.

[0035] R 3 It represents hydrogen atoms, halogen atoms, alkyl groups having 1 to 3 carbon atoms, or -CO-OCH3.

[0036] R 4 Indicates alkyl group,

[0037] L indicates alkylene.

[0038] Z represents -CO-O-* or -O-CO-*, where * indicates that it is related to R. 4 The bonding position,

[0039] m represents 0 or 1, and n represents an integer greater than or equal to 1.

[0040] Equation (3): -CO-CR 1 =CXY

[0041] In equation (3), X, Y and R 1respectively with X, Y and R in equation (1) 1 The definitions are the same.

[0042] [4] The manufacturing method as described in [3], wherein the aqueous medium containing the specific polymer is an aqueous medium used for the manufacture of the specific polymer until the specific polymer is present.

[0043] [5] The manufacturing method as described in [3] or [4], wherein the amount of the specific polymer present in the polymerization of the fluorinated monomer is 0.0001 to 1.0 parts by mass relative to 100 parts by mass of the aqueous medium.

[0044] [6] A method for manufacturing a fluoropolymer, wherein, in an aqueous medium, at least one fluorinated monomer selected from tetrafluoroethylene, trichlorofluoroethylene and vinylidene fluoride is polymerized to manufacture the fluoropolymer in the presence of a polyolefin oxide and in the absence of a substantial emulsifier (wherein, when the tetrafluoroethylene is polymerized, the tetrafluoroethylene is copolymerized under the condition that the content of the tetrafluoroethylene-based unit in the fluoropolymer is less than 99% by mass relative to all units of the fluoropolymer).

[0045] [7] An aqueous dispersion of a fluoropolymer comprising an aqueous medium, particles having units based on at least one fluorinated monomer selected from tetrafluoroethylene, trichlorofluoroethylene, and vinylidene fluoride (wherein, in the case where the tetrafluoroethylene-based unit is included in the fluoropolymer, the content of the tetrafluoroethylene-based unit in the fluoropolymer is less than 99% by mass relative to all units of the fluoropolymer) and having a volume-based cumulative 50% diameter of 20 to 3000 nm, and a specific polymer having at least one unit selected from units based on compounds represented by formula (1) and units based on compounds represented by formula (2), the specific polymer being contained as particles in the aqueous medium or in the particles containing the fluoropolymer, the aqueous dispersion being substantially free of emulsifiers:

[0046] Equation (1): CXY = CR 1 -COO-(LO) n -R 2

[0047] Equation (2): CXY = CR 3 -(O) m -CH2-ZR 4

[0048] The symbols in equations (1) and (2) have the following meanings:

[0049] X and Y independently represent hydrogen atoms, halogen atoms, or methyl groups.

[0050] R 1 Indicates a hydrogen atom, a halogen atom, or an alkyl group having 1 to 3 carbon atoms.

[0051] R 2 The group represents an alkyl group, an alkyl group in which at least one -CH2- is replaced by -CO-, or a group represented by formula (3) below.

[0052] R 3 It represents hydrogen atoms, halogen atoms, alkyl groups having 1 to 3 carbon atoms, or -CO-OCH3.

[0053] R 4 Indicates alkyl group,

[0054] L indicates alkylene.

[0055] Z represents -CO-O-* or -O-CO-*, where * indicates that it is related to R. 4 The bonding position,

[0056] m represents 0 or 1, and n represents an integer greater than or equal to 1.

[0057] Equation (3): -CO-CR 1 =CXY

[0058] In equation (3), X, Y and R 1 respectively with X, Y and R in equation (1) 1 The definitions are the same.

[0059] [8] The aqueous dispersion of the fluoropolymer as described in [7] contains 1.0 to 50.0 parts by mass of the fluoropolymer-containing particles per 100 parts by mass relative to the aqueous medium.

[0060] [9] An aqueous dispersion of a fluoropolymer as described in [7] or [8], comprising 0.0001 to 1.0 parts by mass of the particles of the particular polymer relative to 100 parts by mass of an aqueous medium.

[0061]

[10] An aqueous dispersion of a fluoropolymer as described in any one of [7] to [9], wherein the dispersion comprises 0.001 to 5.00 parts by mass of the particles of the particular polymer relative to 100 parts by mass of the particles containing the fluoropolymer.

[0062]

[11] An aqueous dispersion of a fluoropolymer comprising an aqueous medium, a fluoropolymer having units based on at least one fluorinated monomer selected from tetrafluoroethylene, trichlorofluoroethylene and vinylidene fluoride (wherein, in the case where the fluoropolymer contains the tetrafluoroethylene-based units, the content of the tetrafluoroethylene-based units in the fluoropolymer is less than 99% by mass relative to all units of the fluoropolymer) and particles having a cumulative diameter of 20 to 3000 nm on a volume basis of 50%, and a polyolefin oxide compound, and substantially free of emulsifiers.

[0063]

[12] A polymer composition comprising a fluoropolymer having units based on at least one fluorinated monomer selected from tetrafluoroethylene, trichlorofluoroethylene, and vinylidene fluoride (wherein, in the case where the fluoropolymer contains the tetrafluoroethylene-based units, the content of the tetrafluoroethylene-based units in the fluoropolymer is less than 99% by mass relative to all units of the fluoropolymer), and a specific polymer having at least one unit selected from units based on compounds represented by formula (1) and units based on compounds represented by formula (2), and substantially free of emulsifiers:

[0064] Equation (1): CXY = CR 1 -COO-(LO) n -R 2

[0065] Equation (2): CXY = CR 3 -(O) m -CH2-ZR 4

[0066] The symbols in equations (1) and (2) have the following meanings:

[0067] X and Y independently represent hydrogen atoms, halogen atoms, or methyl groups.

[0068] R 1 Indicates a hydrogen atom, a halogen atom, or an alkyl group having 1 to 3 carbon atoms.

[0069] R 2 The group represents an alkyl group, an alkyl group in which at least one -CH2- is replaced by -CO-, or a group represented by formula (3) below.

[0070] R 3 It represents hydrogen atoms, halogen atoms, alkyl groups having 1 to 3 carbon atoms, or -CO-OCH3.

[0071] R 4 Indicates alkyl group,

[0072] L indicates alkylene.

[0073] Z represents -CO-O-* or -O-CO-*, where * indicates that it is related to R. 4 The bonding position,

[0074] m represents 0 or 1, and n represents an integer greater than or equal to 1.

[0075] Equation (3): -CO-CR 1 =CXY

[0076] In equation (3), X, Y and R 1 respectively with X, Y and R in equation (1) 1 The definitions are the same.

[0077]

[13] The polymer composition as described in

[12] , wherein the content of the particular polymer relative to 100 parts by weight of the fluoropolymer is 0.001 to 5.00 parts by weight.

[0078]

[14] A polymer composition comprising a fluoropolymer having units based on at least one fluorinated monomer selected from tetrafluoroethylene, trichlorofluoroethylene and vinylidene fluoride (wherein the fluoropolymer contains the tetrafluoroethylene-based units, the content of the tetrafluoroethylene-based units in the fluoropolymer is less than 99% by mass relative to all units of the fluoropolymer), and a polyolefin oxide compound, and substantially free of emulsifiers.

[0079] Invention Effects

[0080] According to the present invention, a method for manufacturing a fluoropolymer that does not require an emulsifier even when using an aqueous medium with low environmental impact can be provided.

[0081] Furthermore, according to the present invention, an aqueous dispersion of a fluoropolymer and a polymer composition may also be provided. Detailed Implementation

[0082] The meanings of the terms used in this invention are as follows.

[0083] The content (mass%) of each unit relative to all units contained in a polymer can be determined by analyzing the polymer using solid-state nuclear magnetic resonance (NMR) or estimated from the amount of each monomer added. Typically, the content of each unit calculated from the amount of each monomer added is approximately the same as the actual content of each unit.

[0084] "Volume-based cumulative 50% diameter" refers to the particle size at the point on the cumulative curve where the cumulative volume reaches 50%, obtained by measuring particle size distribution using laser diffraction and scattering with the total volume of the particle cluster as 100%. It is also hereinafter referred to as "D50".

[0085] <<First Embodiment>>

[0086] A first embodiment of the method for manufacturing the fluoropolymer of the present invention is a method for polymerizing at least one fluorinated monomer (hereinafter also referred to as "specific fluorinated monomer") selected from tetrafluoroethylene, trichlorofluoroethylene, and vinylidene fluoride in an aqueous medium in the presence of a specific polymer comprising at least one unit selected from a compound represented by formula (1) (hereinafter also referred to as "compound (1)") and a compound represented by formula (2) (hereinafter also referred to as "compound (2)"). In the case of polymerizing tetrafluoroethylene, the tetrafluoroethylene is copolymerized under the condition that the content of the tetrafluoroethylene-based unit in the fluoropolymer is less than 99% by mass relative to all units of the fluoropolymer.

[0087] The first embodiment of the method for manufacturing the fluoropolymer of the present invention can use a specific polymer obtained by further polymerization, or the specific polymer can be polymerized in an aqueous medium, and then the specific fluorinated monomer can be polymerized in the same polymerization system. Polymerization in the same polymerization system means using an aqueous medium used to manufacture the specific polymer, in which the specific polymer is present, and polymerizing the specific fluorinated monomer in such an aqueous medium. The specific polymer obtained by further polymerization can be a commercially available product.

[0088] As a first embodiment of the method for manufacturing the fluoropolymer of the present invention, it is preferable to polymerize at least one specific compound selected from compound (1) and compound (2) in an aqueous medium to obtain an aqueous medium containing the specific polymer, and then polymerize a specific fluorinated monomer in the aqueous medium containing the specific polymer to manufacture the fluoropolymer. In this two-stage manufacturing method, the stage of obtaining the aqueous medium containing the specific polymer in the previous stage will be referred to as "step 1", and the stage of manufacturing the fluoropolymer in the next stage will be referred to as "step 2".

[0089] The polymerization of compound (1) in step 1 and the polymerization of the specific fluorinated monomer in step 2 are preferably carried out in the presence of a polymerization initiator. A water-soluble polymerization initiator is preferred as the polymerization initiator.

[0090] <Process 1>

[0091] (Specific compound)

[0092] In step 1, at least one specific compound selected from compound (1) and compound (2) is used. Two or more specific compounds may also be used in combination.

[0093] Equation (1): CXY = CR 1 -COO-(LO) n -R 2

[0094] Equation (2): CXY = CR 3 -(O) m -CH2-ZR 4

[0095] The symbols in equations (1) and (2) have the following meanings:

[0096] X and Y independently represent hydrogen atoms, halogen atoms, or methyl groups.

[0097] R 1 R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 3 carbon atoms. 2 R represents an alkyl group, an alkyl group in which at least one -CH2- is replaced by -CO- (hereinafter also referred to as "substituted alkyl group"), or a group represented by formula (3) below. 3 Represents hydrogen atoms, halogen atoms, alkyl groups having 1 to 3 carbon atoms, or -CO-OCH3, R 4 Indicates alkyl group,

[0098] L represents an alkylene group, and Z represents -CO-O-* or -O-CO-* (where * indicates a group with R). 4 (the bond position), where m represents 0 or 1, and n represents an integer greater than or equal to 1.

[0099] Equation (3): -CO-CR 1 =CXY

[0100] In equation (3), X, Y and R 1 respectively with X, Y and R in equation (1) 1 The definitions are the same.

[0101] From the perspective of easily obtaining a specific polymer, each group in formula (1) is preferably the group shown below.

[0102] X and Y are preferably hydrogen atoms, fluorine atoms, or chlorine atoms that are independent of each other, and more preferably both are hydrogen atoms.

[0103] As R 1 Preferably, it is an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group.

[0104] As L, it is preferably an alkylene group having 2 to 6 carbon atoms, more preferably an alkylene group having 2 or 3 carbon atoms, and even more preferably an ethyl group. The alkylene group of L can be linear or branched.

[0105] As R 2 Alkyl groups, preferably alkyl groups having 1 to 3 carbon atoms, and more preferably methyl groups.

[0106] As R 2The number of groups represented by -CO- in the substituted alkyl group is preferably 1 to 3, more preferably 2. The position of -CO- in the substituted alkyl group can be at the end of the substituted alkyl group or between -CH2- and -CH2-. As R 2 The substituted alkyl group is preferably -CO-CH2-CO-CH3.

[0107] R 2 The groups X, Y and R represented by formula (3) 1 respectively with X, Y and R in equation (1) 1 The definitions are the same, and the preferred forms are also the same.

[0108] As n, 1 to 100 is preferred, and 1 to 50 is more preferred.

[0109] As compound (1), the preferred compounds are those represented by formula (1A), formula (1B), and formula (1C).

[0110] Equation (1A): CXY = CR 1 -COO-(LO) n -R 2a

[0111] Equation (1B): CXY = CR 1 -COO-(LO) n -CO-CR 1 =CXY

[0112] Equation (1C): CXY = CR 1 -COO-LOR 2b

[0113] In equations (1A), (1B), and (1C), X, Y, and R 1 L and n are respectively related to X, Y, and R in equation (1). 1 The definitions of L and n are the same.

[0114] In equation (1A), R 2a Indicates alkyl group.

[0115] In equation (1C), R 2b Indicates a substituted alkyl group.

[0116] From the perspective of easily obtaining specific polymers, the groups in formula (2) are preferably the groups shown below.

[0117] In equation (2), the preferred ranges of X and Y are the same as those of X and Y in equation (1).

[0118] As R 3 Preferably, it is an alkyl group with 1 to 3 carbon atoms or -CO-OCH3.

[0119] As for Z, -O-CO-* is preferred.

[0120] As R 4 Preferably, it is an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group.

[0121] m is preferred 0.

[0122] As compound (2), the preferred compound is the one represented by formula (2A).

[0123] Equation (2A)CXY=CR 3a -CH2-O-CO-R 4

[0124] In equation (2A), X, Y, and R 4 respectively with X, Y and R in equation (2) 4 The definitions are the same.

[0125] As R 3a , indicating an alkyl group having 1 to 3 carbon atoms.

[0126] (Aqueous medium)

[0127] Examples of aqueous media include water and mixtures of water and water-soluble organic solvents.

[0128] Examples of water-soluble organic solvents include tert-butanol, propylene glycol, and dipropylene glycol. In the case of a mixture of water and a water-soluble organic solvent, the concentration of the water-soluble organic solvent is preferably 10% by mass or less. As an aqueous medium, water alone is preferred.

[0129] (Water-soluble polymerization initiator)

[0130] As a water-soluble polymerization initiator, water-soluble free radical initiators and water-soluble redox catalysts are preferred.

[0131] As water-soluble free radical initiators, 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 are preferred.

[0132] 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 and ammonium persulfate are preferred as persulfates. Sodium sulfite is preferred as a sulfite. Combinations of sulfate anions, sulfite anions, or chloride anions with metal ions are possible as inorganic salts. Transition metal ions are preferred, including ions of manganese, iron, cobalt, nickel, copper, zinc, cerium, and silver, with iron ions being particularly preferred. Ferric(II) sulfate is preferred as an inorganic salt.

[0133] As a water-soluble polymerization initiator, a water-soluble redox catalyst is preferred, and combinations of potassium persulfate and sodium sulfite, or combinations of potassium persulfate, sodium sulfite, and inorganic salts are preferred, with combinations of potassium persulfate and sodium sulfite and combinations of potassium persulfate, sodium sulfite, and ferric sulfate (II) being even more preferred.

[0134] Furthermore, considering the ease of polymerization of specific compounds, the pH of the reaction system is preferably set to 3–10, or 6–8. To adjust this, sulfites such as sodium sulfite, ammonia, sodium hydroxide, hydrochloric acid, etc., can be added as needed.

[0135] Water-soluble polymerization initiators can also be used in combination of two or more.

[0136] In addition, as a water-soluble polymerization initiator, it can be added to the reaction system in its entirety before the polymerization reaction begins, or it can be added to the reaction system continuously or intermittently.

[0137] The amount of the specific compound used relative to 100 parts by mass of the aqueous medium is preferably 0.0001 to 1.0 parts by mass, more preferably 0.001 to 0.5 parts by mass. Within this range, not only can a decrease in the polymerization rate be prevented, but also the amount of the specific polymer mixed with the fluoropolymer can be reduced when manufacturing the fluoropolymer in step 2. Furthermore, as a method of adding the specific compound, it is preferable to add its entire amount to the reaction system in a single, initial addition before the polymerization reaction begins.

[0138] The amount of water-soluble polymerization initiator used relative to 1 mole of a specific compound is preferably 0.1 to 50.0 moles, more preferably 0.1 to 40.0 moles, and even more preferably 0.5 to 10.0 moles.

[0139] The polymerization temperature of the specific compound is preferably 10–95°C, more preferably 50–90°C. In the case of batch processing, the time is preferably 5–400 minutes, more preferably 5–300 minutes.

[0140] The preferred pressure conditions for polymerization are reduced pressure or normal pressure.

[0141] The above polymerization process yields an aqueous dispersion containing a specific polymer. The specific polymer is uniformly dispersed in the aqueous medium in particulate form. The aqueous dispersion is in a colloidal state.

[0142] It is hypothesized that specific polymer particles (hereinafter also referred to as "specific particles") introduce specific fluorinated monomers into the polymerization process of these monomers via their hydrophobic portions, thereby making the specific fluorinated monomers soluble. The addition of an initiator then facilitates the polymerization of the specific fluorinated monomers within the specific particles. It is also hypothesized that specific particles contribute to dispersion stabilization in aqueous media and organic solvents.

[0143] The D50 of a specific particle is preferably 10-1000 nm, more preferably 10-300 nm, even more preferably 10-200 nm, and particularly preferably 10-150 nm.

[0144] The specific particles are composed of a specific polymer containing units based on a specific compound (units based on compound (1) and units based on compound (2)).

[0145] The content of units based on a specific compound in a specific polymer is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more, relative to all units of the specific polymer. As an upper limit, 100% by mass can be listed.

[0146] Through the above polymerization, an aqueous dispersion of a fluoropolymer containing 0.0001 to 1.0 parts by mass of specific particles with a D50 of 10 to 1000 nm can be readily obtained relative to 100 parts by mass of an aqueous medium. Preferably, the specific particles are contained in 0.0001 to 0.5 parts by mass relative to 100 parts by mass of the aqueous medium, more preferably 0.0005 to 0.1 parts by mass.

[0147] <Process 2>

[0148] Step 2 is a manufacturing step of polymerizing at least one fluorinated monomer (i.e., a specific fluorinated monomer) selected from tetrafluoroethylene, trifluorochloroethylene and vinylidene fluoride in an aqueous medium containing a specific polymer obtained from Step 1.

[0149] The polymerization of a specific fluorinated monomer is preferably carried out using a water-soluble polymerization initiator. Examples of such water-soluble polymerization initiators include those described in step 1. Furthermore, the polymerization of the specific fluorinated monomer is also preferably carried out using a chain transfer agent.

[0150] Fluoropolymers include tetrafluoroethylene polymers containing tetrafluoroethylene (TFE)-based units (hereinafter also referred to as "TFE units"), polyvinylidene fluoride (hereinafter also referred to as "PVdF"), polychlorotrifluoroethylene, and copolymers of ethylene and chlorotrifluoroethylene. Among these, tetrafluoroethylene polymers are preferred.

[0151] Fluoropolymers can have units based on monomers other than specific fluorinated monomers.

[0152] Other monomers, and fluorinated monomers, include hexafluoropropylene (hereinafter also referred to as "HFP"), perfluoro(alkyl vinyl ether) (hereinafter also referred to as "PAVE"), and fluoroalkyl vinyl ether (hereinafter also referred to as "FAE").

[0153] As PAVE, examples include CF2 = CFOCF3 (hereinafter also referred to as "PMVE"), CF2 = CFOCF2CF3, CF2 = CFOCF2CF2CF3 (hereinafter also referred to as "PPVE"), CF2 = CFOCF2CF2CF2CF3, and CF2 = CFO(CF2)8F, with PMVE and PPVE being preferred.

[0154] As FAEs, CH2=CH(CF2)2F (hereinafter also referred to as "PFEE"), CH2=CH(CF2)3F, CH2=CH(CF2)4F (hereinafter also referred to as "PFBE"), CH2=CF(CF2)3H, and CH2=CF(CF2)4H can be listed, with PFEE and PFBE being preferred.

[0155] In addition, other monomers that can be listed include ethylene, propylene, vinyl chloride, vinylidene chloride, and vinyl fluoride.

[0156] In addition, monomers having oxygen-containing polar groups can also be listed as other monomers. Preferably, the oxygen-containing polar group consists of anhydride residues, hydroxyl groups, carbonyl groups, acetal groups, and oxycycloalkane groups, with anhydride residues being more preferred. Among monomers having anhydride residues, monomers having cyclic anhydride residues are preferred, with itaconic anhydride (hereinafter also referred to as "IAH"), citraconic anhydride, 5-norbornene-2,3-dicarboxylic anhydride (also known as nadic anhydride, hereinafter also referred to as "NAH"), and maleic anhydride being more preferred.

[0157] Examples of tetrafluoroethylene polymers include copolymers of TFE and PAVE, copolymers of TFE and HFP (hereinafter also referred to as "FEP"), copolymers of TFE and ethylene (hereinafter also referred to as "ETFE"), copolymers of TFE and propylene, and copolymers of TFE and vinylidene fluoride.

[0158] In the case of TFE polymerization, TFE is copolymerized under the condition that the content of TFE units in the fluoropolymer is less than 99% by mass relative to all units of the fluoropolymer. Furthermore, when TFE units are included but not containing units based on at least one fluorinated monomer selected from trichlorotrifluoroethylene and vinylidene fluoride, the content of TFE units is preferably 10% by mass or more and less than 99% by mass relative to all units of the fluoropolymer.

[0159] Furthermore, tetrafluoroethylene polymers do not include the specific high heat-resistant polymers described below.

[0160] Specific high heat-resistant polymers: polymers whose initial endothermic peak is at least 330°C or higher and whose endothermic peak is at least 320°C or higher when heated by differential scanning calorimetry at a rate of 10°C / min.

[0161] As the tetrafluoroethylene polymers of the present invention, ETFE, copolymers of TFE and PAVE and FEP are preferred, and ETFE and PFA described later are more preferred.

[0162] As a FEP, it is preferred that the proportion of HFP units to the total proportion of TFE units and HFP units is 1 to 15 mol%, and more preferably 5 to 13 mol%.

[0163] ETFE has TFE units and ethylene-based units (hereinafter also referred to as "E units"). In copolymers having TFE units and E units, the proportion of E units relative to the total of E units and TFE units is preferably 20 to 70 mol%, more preferably 25 to 60 mol%, and even more preferably 35 to 55 mol%.

[0164] The total proportion of E units and TFE units relative to all units constituting ETFE is preferably 80 mol% or more, more preferably 85 mol% or more, and even more preferably 90 mol% or more.

[0165] In addition to the E unit and the TFE unit, it is preferable to also have a FAE unit. The proportion of the FAE unit relative to the total of the E unit and the TFE unit is preferably 0.1 to 10 mol%, more preferably 0.1 to 5 mol%, and even more preferably 0.2 to 4 mol%.

[0166] In addition to the E unit and TFE unit, it is preferable to also contain monomer units having oxygen-containing polar groups. The proportion of monomer units having oxygen-containing polar groups relative to the total of E units and TFE units is preferably 0.01 to 5 mol%, more preferably 0.05 to 3 mol%. Although the method for manufacturing the fluoropolymer of the present invention uses emulsion polymerization in an aqueous medium, even when using monomers with oxygen-containing polar groups, such as monomers with highly hydrophilic monomers having cyclic anhydride residues, excessive dissolution is avoided, and copolymerization with tetrafluoroethylene and the like is easily achieved, allowing for the easy introduction of oxygen-containing polar groups into the fluoropolymer.

[0167] The copolymer of TFE and PAVE has TFE units and PAVE units. As a copolymer of TFE and PAVE, it is preferred to be a copolymer in which the proportion of PAVE units to the total proportion of TFE units and PAVE units is more than 0.1 mol% and less than 20 mol% (hereinafter also referred to as "PF1"), and a copolymer in which the proportion of PAVE units is 20 to 70 mol% (hereinafter also referred to as "PF2").

[0168] In PF1, the proportion of PAVE units relative to the total of TFE units and PAVE units is preferably 0.5 to 10 mol%, more preferably 0.5 to 5.0 mol%.

[0169] PF1 can be a copolymer consisting only of TFE and PAVE units, or it can also contain one or more other units based on other monomers.

[0170] Other monomers are preferred, including other fluorinated monomers or monomers having oxygen-containing polar groups. Hexafluoropropylene is preferred among other fluorinated monomers. NAH is preferred among monomers having oxygen-containing polar groups.

[0171] When the unit also includes units based on other monomers, the proportion of other fluorinated monomers relative to the total of the TFE unit and the PAVE unit is preferably 0.1 to 10 mol%, more preferably 0.1 to 6 mol%. The monomer having an oxygen-containing polar group is preferably 0.01 to 5 mol%, more preferably 0.05 to 3 mol%.

[0172] The total proportion of TFE units and PAVE units relative to all units constituting PF1 is preferably 80 mol% or more, more preferably 85 mol% or more, and even more preferably 90 mol% or more.

[0173] Additionally, PF1 and below are also referred to as "PFA".

[0174] In PF2, the proportion of PAVE units relative to the total of TFE units and PAVE units is preferably 20 to 50 mol%, more preferably 25 to 45 mol%.

[0175] In addition to the TFE unit and the PAVE unit, it is preferable to also contain a unit based on a monomer having fluorine atoms and nitrile groups (hereinafter also referred to as "CN unit") and a unit based on a monomer having fluorine atoms and multiple vinyl groups (hereinafter also referred to as "DV unit").

[0176] As monomers with fluorine atoms and nitrile groups, examples include CF2=CFO(CF2)5CN and CF2=CFOCF2CF(CF3)CF2CF2CN.

[0177] Examples of monomers containing fluorine atoms and multiple vinyl groups include CF2=CFO(CF2)3OCF=CF2, CF2=CFO(CF2)4OCF=CF2, and CH2=CH(CF2)6CH=CH2.

[0178] The proportion of CN units relative to the total of TFE units and PAVE units is preferably 0.1 to 10.0 mol%, more preferably 0.5 to 5.0 mol%.

[0179] The ratio of DV units to the total of TFE units and PAVE units is preferably 0.01 to 1.0 mol%, more preferably 0.01 to 0.5 mol%.

[0180] The total proportion of TFE units and PAVE units relative to all units constituting PF2 is preferably 80 mol% or more, more preferably 85 mol% or more, and even more preferably 90 mol% or more.

[0181] Specific fluorinated monomers and other monomers are added to the reaction system (i.e., the polymerization reactor) using conventional methods. For example, TFE is added to the reaction system continuously or intermittently to bring the polymerization pressure to a specified level. Alternatively, other monomers are dissolved in an aqueous medium and the resulting solution is added to the reaction system continuously or intermittently.

[0182] When using water-soluble polymerization initiators, the water-soluble polymerization initiators can be added to the reaction system all at once or in batches.

[0183] When using a chain transfer agent, alcohols, hydrocarbons, and hydrofluorocarbons are preferred, with alcohols and hydrocarbons being more preferred, considering their effect of stabilizing the resin terminal structure. As for alcohols, methanol and ethanol are preferred, considering their easy solubility in water and ease of separation from the copolymer after manufacturing. As for hydrocarbons, n-pentane, cyclohexane, methane, and propane are preferred, as they offer good thermal stability and high chain transferability when introduced into the resin terminal structure.

[0184] The polymerization temperature is preferably 10–95°C, more preferably 15–90°C. The polymerization pressure is preferably 0.5–4.0 MPaG, more preferably 0.6–3.5 MPaG. The polymerization time, in the case of batch processing, is preferably 90–1000 minutes, more preferably 90–700 minutes.

[0185] The polymerization of certain fluorinated monomers can be carried out under conditions where the emulsifier is substantially absent.

[0186] As emulsifiers, well-known emulsifiers and general surfactants can be listed.

[0187] Furthermore, the emulsifiers mentioned above do not refer to the specific polymers of this invention, the polyolefin oxides described later, or the decomposition products obtained by mixing polyolefin oxides with oxidants.

[0188] The condition where the emulsifier is substantially absent means that the emulsifier content relative to the total mass of the aqueous medium is less than 0.03 ppm by mass, preferably less than 0.02 ppm by mass, and more preferably 0 ppm by mass.

[0189] Furthermore, the manufacture of specific polymers and fluoropolymers can be carried out continuously within the same polymerization reactor.

[0190] Furthermore, in the manufacturing method of the present invention, it is possible to form specific particles during the manufacturing of a specific polymer, or to manufacture a fluoropolymer before the specific compound is completely consumed. In this case, it is considered possible to form a fluoropolymer containing units based on the specific compound.

[0191] When the manufacture of a specific polymer and the manufacture of a fluoropolymer are carried out continuously, the content of the specific polymer obtained from step 1 and present in step 2 in the aqueous medium is preferably 0.0001 to 1.0 parts by mass relative to 100 parts by mass of the aqueous medium, more preferably 0.0005 to 0.5 parts by mass.

[0192] If the manufacturing of the specific polymer and the manufacturing of the fluoropolymer are not carried out sequentially, step 1 can be omitted. A commercially available specific polymer is prepared to replace step 1, and the content of the specific polymer present in step 2 in the aqueous medium is preferably 0.0001 to 1.0 parts by mass relative to 100 parts by mass of the aqueous medium, more preferably 0.001 to 0.5 parts by mass.

[0193] Commercially available polymers preferably have a particle D50 of 10–1000 nm, more preferably 10–300 nm, even more preferably 10–200 nm, and particularly preferably 10–150 nm.

[0194] Furthermore, the content of units based on a specific compound in a commercially available polymer is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more, relative to all units of the polymer. As an upper limit, 100% by mass can be listed.

[0195] Through the above steps, it is easy to obtain an aqueous dispersion of fluoropolymer containing particles with a D50 of 20-3000 nm of fluoropolymer having units based on specific fluorinated monomers and specific particles.

[0196] Furthermore, as mentioned above, it is hypothesized that during the polymerization of a specific fluorinated monomer, the monomer polymerizes within a specific particle, thus generating fluorinated polymer particles that enter the specific particle, producing particles containing both the fluorinated polymer and the specific polymer. In particular, when the specific particle has a high affinity for the specific fluorinated monomer (e.g., when the specific particle is a particle of a specific polymer having fluorine atoms), it is believed that particles with a D50 of 20–3000 nm containing both the fluorinated polymer and the specific polymer are easily generated.

[0197] The aqueous dispersion of the fluoropolymer of the present invention is preferably an aqueous dispersion comprising, as described above, an aqueous medium, particles containing a fluoropolymer with a D50 of 20 to 3000 nm, and a specific polymer contained as particles in the aqueous medium or contained in the aforementioned particles containing the fluoropolymer.

[0198] Unless otherwise specified, particles containing fluoropolymers are also particles that may contain specific polymers.

[0199] The aqueous dispersion of fluoropolymer contains particles containing fluoropolymer, preferably 1.0 to 50.0 parts by mass, more preferably 2.0 to 40.0 parts by mass, relative to 100 parts by mass of the aqueous medium.

[0200] The aqueous dispersion of the fluoropolymer preferably contains 0.0001 to 1.0 parts by weight of a specific polymer relative to 100 parts by weight of the aqueous medium.

[0201] Furthermore, in the aqueous dispersion of the fluoropolymer, the content of the specific polymer relative to 100 parts by mass of the particles containing the fluoropolymer is preferably 0.001 to 5.00 parts by mass, more preferably 0.005 to 3.00 parts by mass.

[0202] The D50 of particles containing fluoropolymers is preferably 20–1000 nm.

[0203] The above-mentioned aqueous dispersion of fluoropolymers does not actually contain emulsifiers.

[0204] The emulsifier is as described above.

[0205] The absence of emulsifier in the aqueous dispersion of fluoropolymer means that the content of emulsifier relative to the total mass of the aqueous medium is less than 0.03 ppm by mass, preferably less than 0.02 ppm by mass, and more preferably 0 ppm by mass.

[0206] Furthermore, in the case where the fluoropolymer contained in the aqueous dispersion of the fluoropolymer includes TFE units, the content of TFE units in the fluoropolymer is less than 99% by mass relative to all units of the fluoropolymer.

[0207] As described above, the above-mentioned aqueous dispersion of fluoropolymer does not require an emulsifier, and therefore it is easy to obtain dispersions of organic solvents such as N-methylpyrrolidone and acetone by solvent substitution.

[0208] A dispersion of an organic solvent can be formed by mixing an aqueous dispersion of a fluoropolymer containing particles of a fluoropolymer with an organic solvent and then evaporating or dehydrating it with anhydrous sodium sulfate, etc.

[0209] Although the above-mentioned aqueous dispersions of fluoropolymers do not contain emulsifiers, the fluoropolymers remain stably dispersed. Therefore, they are suitable for coating applications, adhesives, etc.

[0210] The polymer compositions of the present invention are preferably compositions comprising a specific polymer, or fluoropolymers containing units based on a specific fluorinated monomer.

[0211] The polymer composition described above can be readily obtained from the aqueous dispersion of the fluoropolymer obtained in step 2. That is, the polymer composition powder can be obtained by agglomerating the polymer from the aqueous dispersion of the fluoropolymer. Furthermore, the powdered polymer composition obtained by agglomeration can be homogenized by melt mixing or the like to produce a molding material containing the fluoropolymer and a specific polymer in the form of granules or particles. The powdered polymer composition obtained by agglomeration can also be molded into a molded article by melt molding or the like.

[0212] Examples of coagulation methods include freeze coagulation, acid coagulation, alkali coagulation, and coagulation using coagulants, but these are not limited to.

[0213] In the case of freeze-coagulation, the coagulation temperature is preferably 0–5°C. The coagulation time is preferably 1 hour or more, more preferably 2 hours or more.

[0214] In the event of acid coagulation, it is preferable to add an acid-containing solution to an aqueous dispersion of the fluoropolymer. Examples of acids that can be added include hydrochloric acid, nitric acid, sulfuric acid, oxalic acid, and hydrofluoric acid, with hydrochloric acid being preferred. The concentration of the acid in the acid-containing solution is preferably 0.1–50% by mass, more preferably 1–30% by mass, and even more preferably 1–10% by mass.

[0215] As a method for alkaline coagulation, it is preferable to add an alkaline solution to an aqueous dispersion of a fluoropolymer. Examples of alkaline substances to be added include sodium hydroxide, potassium hydroxide, and ammonium carbonate, with sodium hydroxide being preferred. The concentration of the alkaline solution is preferably 0.1–50% by mass, more preferably 1–30% by mass, and even more preferably 1–10% by mass.

[0216] For coagulation using a condensing agent, known condensing agents can be used. Examples of known condensing agents include ammonium salts, calcium salts, and magnesium salts. Specifically, examples include aluminum sulfate and condensate with the general formula M'Al(SO4)2· 12 H2O (where M' is a monovalent cation other than lithium) represents alum, calcium nitrate, and magnesium sulfate, with alum being preferred, and potassium alum, where M is potassium, being more preferred.

[0217] As a coagulation method, alkaline coagulation is preferred from the perspective that coagulation is particularly easy to carry out.

[0218] The melting point of the fluoropolymer in the polymer composition is preferably above 150°C, more preferably 150–330°C, further preferably 180–320°C, particularly preferably 220–310°C, and most preferably 260–300°C. If the melting point is within this range, the fluoropolymer exhibits high heat resistance and is therefore preferred.

[0219] The polymer composition described above is preferably substantially free of emulsifiers.

[0220] The emulsifier is as described above.

[0221] The polymer composition is substantially free of emulsifiers, meaning that the emulsifier content is less than 0.03 ppm by mass, preferably less than 0.02 ppm by mass, and more preferably 0 ppm by mass, relative to the total mass of the specific polymer in the polymer composition and the fluoropolymer containing units based on the specific fluoromonomer.

[0222] <<Second Implementation>>

[0223] A second embodiment of the method for manufacturing fluoropolymers of the present invention is a method for polymerizing a specific fluoropolymer in an aqueous medium under conditions where a polyolefin oxide compound is present and an emulsifier is substantially absent. Specifically, when polymerizing TFE, the TFE is copolymerized under conditions where the content of TFE units in the fluoropolymer is less than 99% by mass relative to all units of the fluoropolymer.

[0224] In the first embodiment of the method for manufacturing the fluoropolymer described above, the polymerization of a specific fluorinated monomer was carried out in the presence of a specific polymer. In contrast, in the second embodiment of the method for manufacturing the fluoropolymer, the specific fluorinated monomer is polymerized in the presence of a polyolefin compound and in the absence of a substantial emulsifier. That is, the second embodiment of the method for manufacturing the fluoropolymer differs from the first embodiment in that it uses a polyolefin compound, but the polymerization step of the specific fluorinated monomer in the second embodiment is the same as the polymerization step of the specific fluorinated monomer in the first embodiment (specifically, step 2). Therefore,

[0225] The following mainly describes the differences between the second embodiment and the first embodiment.

[0226] (polyalkylene oxide compound)

[0227] Polyolefin oxides are compounds used to form a core (nucleus) during the polymerization of specific fluorinated monomers. In other words, they are equivalent to core-forming additives.

[0228] Polyoxyethylene compounds refer to compounds containing polyoxyethylene chains. Examples of polyoxyethylene chains include polyoxyethylene chains, polyoxypropylene chains, and polyoxytetramethylene chains.

[0229] The polyolefin oxide preferably has a surface tension in water greater than about 40 dynes / cm at a concentration of 1000 ppm. More preferably, the surface tension is greater than about 42 dynes / cm, and even more preferably greater than about 45 dynes / cm. The surface tension is preferably less than about 73 dynes / cm.

[0230] The number average molecular weight of the polyolefin is preferably 50 to 2000, more preferably 100 to 1500, and even more preferably 150 to 1300.

[0231] As a polyolefin oxide compound, the compound represented by formula (4) is preferred.

[0232] Equation (4): R a -(OR c ) p -OR b

[0233] In equation (4), R a and R b Each can be independently represented by a hydrogen atom, alkyl group, acryloyl group, or methacryloyl group.

[0234] R c It refers to alkylene groups having 2 to 4 carbon atoms, which can be linear or branched.

[0235] p represents an integer from 1 to 50.

[0236] Examples of polyolefin compounds include polyethylene glycol, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, polyethylene glycol monomethyl ether, polyethylene glycol dimethyl ether, polyethylene glycol monobutyl ether, polypropylene glycol, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, polyethylene glycol dimethacrylate, polyethylene glycol monomethyl ether, polyethylene glycol dimethyl ether, polyethylene glycol monobutyl ether, and polytetramethylene glycol.

[0237] Polyolefin oxides can be used alone or in combination of two or more.

[0238] The amount of polyolefin oxide used is preferably 0.1 to 10 ppm by mass relative to the total mass of the aqueous medium, more preferably 1 to 10 ppm by mass.

[0239] (Emulsifier)

[0240] In the second embodiment, the polymerization of a specific fluorinated monomer is carried out under conditions where the emulsifier is substantially absent.

[0241] The emulsifier is as described above.

[0242] The condition where the emulsifier is substantially absent means that the amount of emulsifier used relative to the total mass of the aqueous medium is less than 0.03 ppm by mass, preferably less than 0.02 ppm by mass, and more preferably 0 ppm by mass.

[0243] The second embodiment preferably involves mixing a polyolefin oxide compound with an oxidant in an aqueous medium to obtain a dispersion, and then polymerizing a specific fluorinated monomer in the obtained dispersion to manufacture a fluorinated polymer.

[0244] (Oxidizing agent)

[0245] Examples of oxidants include hydrogen peroxide and polymerization initiators.

[0246] Compounds exemplified as water-soluble polymerization initiators described in step 1 above can be used as polymerization initiators. Persulfates are preferred as polymerization initiators, and ammonium persulfate and potassium persulfate are more preferred.

[0247] When a polyolefin oxide compound is mixed with an oxidant in an aqueous medium, a dispersion is obtained in which lipophilic core-forming sites are dispersed in the aqueous medium. More specifically, when a polyolefin oxide compound is mixed with an oxidant, the hydrophilic portion of the polyolefin oxide compound decomposes, and the hydrophobic portion of the polyolefin oxide compound becomes the lipophilic core-forming sites. These lipophilic core-forming sites, dispersed in the aqueous medium, enable the fine dispersion of fluoropolymers.

[0248] Because of the excellent affinity between the lipophilic core-forming site and the specific fluorinated monomer, the polymerization of the specific fluorinated monomer can be easily carried out in a dispersion containing the lipophilic core-forming site. That is, the lipophilic core-forming site can serve as a hydrophobic environment for the polymerization of the specific fluorinated monomer.

[0249] The amount of oxidant used relative to the total mass of the aqueous medium is preferably 0.01 to 1.00% by mass, more preferably 0.05 to 0.5% by mass.

[0250] The temperature at which the polyolefin oxide compound is mixed with the oxidant is preferably 20–120°C, more preferably 40–120°C.

[0251] The mixing time for polyolefin oxides and oxidants is preferably 0.05 to 1.00 hours.

[0252] Before or during mixing of polyolefin oxides and oxidants, it is preferable to add water-soluble inorganic salts to the aqueous medium.

[0253] The amount of water-soluble inorganic salt used relative to the total mass of the aqueous medium is preferably 1 to 1000 ppm by mass, more preferably 10 to 1000 ppm by mass.

[0254] Examples of water-soluble inorganic salts include sodium sulfite, sodium bisulfite, sodium chloride, potassium sulfite, potassium bisulfite, potassium carbonate, ammonium oxalate, sodium tetraborate, sodium acetate, ammonium carbonate, ammonium dihydrogen phosphate, and diammonium phosphate. Sulfites are preferred, and sodium sulfite and ammonium sulfite are more preferred.

[0255] Through the above steps, it is easy to obtain an aqueous dispersion of a fluoropolymer containing particles with a D50 of 20–3000 nm of a fluoropolymer having units based on a specific fluorinated monomer and a polyolefin oxide compound.

[0256] The aqueous dispersion of fluoropolymer contains, preferably, 1.0 to 50.0 parts by weight, more preferably 3 to 40 parts by weight, of fluoropolymer-containing particles relative to 100 parts by weight of the aqueous medium.

[0257] The aqueous dispersion of the fluoropolymer contains 0.1 to 10 ppm of polyolefin oxide relative to the total mass of the aqueous dispersion of the fluoropolymer, preferably 1 to 10 ppm by mass.

[0258] Furthermore, in the aqueous dispersion of the fluoropolymer, the content of polyolefin oxide is preferably 0.001 to 5.00 parts by mass, more preferably 0.005 to 3.00 parts by mass, relative to 100 parts by mass of particles containing the fluoropolymer.

[0259] The D50 of particles containing fluoropolymers is preferably 20–1000 nm.

[0260] The above-mentioned aqueous dispersion of fluoropolymers does not actually contain emulsifiers.

[0261] The emulsifier is as described above.

[0262] The absence of emulsifier in the aqueous dispersion of fluoropolymer means that the emulsifier content is less than 0.03 ppm by mass relative to the total mass of the aqueous medium, preferably less than 0.02 ppm by mass, and more preferably 0 ppm by mass.

[0263] Furthermore, in the case where the fluoropolymer contained in the aqueous dispersion of the fluoropolymer includes TFE units, the content of TFE units in the fluoropolymer is less than 99% by mass relative to all units of the fluoropolymer.

[0264] As described above, the above-mentioned aqueous dispersion of fluoropolymer does not require an emulsifier, and therefore it is easy to obtain dispersions of organic solvents such as N-methylpyrrolidone and acetone by solvent substitution.

[0265] A dispersion of an organic solvent can be formed by mixing an aqueous dispersion of a fluoropolymer containing particles of a fluoropolymer with an organic solvent and then evaporating or dehydrating it with anhydrous sodium sulfate, etc.

[0266] Although the above-mentioned aqueous dispersions of fluoropolymers do not contain emulsifiers, the fluoropolymers remain stably dispersed. Therefore, they are suitable for coating applications, adhesives, etc.

[0267] The polymer compositions of the present invention are preferably compositions comprising polyolefin oxides or fluoropolymers containing units based on specific fluorinated monomers.

[0268] The polymer composition described above can be readily obtained from the aqueous dispersion of the fluoropolymer. That is, the polymer composition powder can be obtained by agglomerating the polymer from the aqueous dispersion of the fluoropolymer. Furthermore, the powdered polymer composition obtained by agglomeration can be homogenized by melt mixing or the like to produce a molded material in the form of granules or particles containing the fluoropolymer and polyolefin oxides. The powdered polymer composition obtained by agglomeration can also be molded into a molded article by melt molding or the like.

[0269] The coagulation method is as described above.

[0270] The polymer composition described above is preferably substantially free of emulsifiers.

[0271] The emulsifier is as described above.

[0272] The polymer composition is substantially free of emulsifiers, meaning that the emulsifier content is less than 0.03 ppm by mass, preferably less than 0.02 ppm by mass, and more preferably 0 ppm by mass, relative to the total mass of the polyolefin oxide and the fluoropolymer containing units based on a specific fluorinated monomer in the polymer composition.

[0273] Example

[0274] The present invention will now be described in detail with reference to examples and comparative examples, but the present invention is not limited thereto. Examples 1 to 7 are equivalent to examples.

[0275] The various measurement and evaluation methods are described below.

[0276] D50 (nm) of polymer particles in aqueous dispersion:

[0277] Aqueous dispersions of polymer particles were used as samples, and particle size distribution was measured using a laser diffraction-scattering particle size analyzer (Otsuka Electronics Co., Ltd. ELSZ).

[0278] Confirmation of specific polymers:

[0279] pass 1 H-NMR analysis confirmed the presence of a specific polymer.

[0280] Q(mm 3 Determination of / s):

[0281] The Q value (also known as volumetric flow rate) of ETFE was determined using a flow tester (manufactured by Shimadzu Corporation) at a temperature of 297°C and a load of 50 kg.

[0282] The proportions of each unit in the polymer:

[0283] The proportions of each unit in the polymer are determined by... 19 The results were obtained through F-NMR analysis, fluorine content analysis, and infrared absorption spectroscopy analysis.

[0284] Melting point (°C):

[0285] The melting point is the temperature at which the heat of fusion occurs during melting, measured using a differential scanning calorimeter (NETZSCH DSC 3500Sirius) under a nitrogen atmosphere. The temperature change sequence during the measurement was -20℃→310℃→-70℃→310℃, with each heating rate of 10℃ / min and a cooling rate of 5℃ / min. The temperature at which the heat of fusion occurs during the second heating after cooling to -70℃ is taken as the melting point.

[0286] [Manufacturing of fluoropolymers]

[0287] (Example 1)

[0288] [Process 1]

[0289] After purging the 2.1L stainless steel polymerization tank with nitrogen, the pressure was reduced to -0.1 MPaG, and ultrapure water (624g), sodium sulfite (74mg), and 2-methoxyethyl methacrylate (hereinafter also referred to as "MEM", see the structural formula below) (34mg) were added. Then, while stirring the solution in the polymerization tank, the temperature was raised to 60°C, and 4.0ml of a solution (5% by mass) of potassium persulfate (hereinafter also referred to as "KPS") dissolved in deionized water was injected into the polymerization tank to polymerize MEM. From the amount of MEM added, it can be seen that 0.0054 parts by mass of polyMEM are present in 100 parts by mass of the aqueous medium.

[0290]

Chemistry 1

[0291]

[0292] [Process 2]

[0293] Next, the polymerization tank was pressurized to 1.9 MPaG using a mixed monomer with a TFE / E molar ratio of 86 / 14. 11.3 ml of a solution of KPS (5% by mass) and sodium acetate (1.2% by mass) dissolved in deionized water, along with 0.7 g of PFBE, was injected into the polymerization tank. After the pressure inside the polymerization tank began to decrease, a mixed monomer with a TFE / E molar ratio of 54 / 46 was added to maintain the internal pressure at 1.9 MPaG, allowing polymerization to continue. At the point when 30 g of mixed monomer had been continuously added, the polymerization tank was cooled to room temperature, and the gases inside the tank were released into the atmosphere. The polymerization time was 329 minutes.

[0294] The obtained aqueous dispersion of the fluoropolymer had a solids concentration of approximately 3.7%. Furthermore, the D50 of the fluoropolymer particles in the aqueous dispersion was 92 nm.

[0295] The aqueous dispersion of the fluoropolymer was cooled, causing the fluoropolymer particles to agglomerate and form a powder. This powder was then dried at 150°C. The Q value of the obtained fluoropolymer powder under a 50 kg load was 8.3 mm. 3 The molar ratio of TFE units / E units / PFBE units in the fluoropolymer is 53.0 / 46.0 / 1.0. The melting point of the obtained fluoropolymer is 266℃.

[0296] (Examples 2~7)

[0297] Fluoropolymers were prepared in the same order as in Example 1, except that the compounds described in Table 1 were used in the prescribed amounts instead of MEM. The results are summarized in Table 1.

[0298] In addition, the symbols for the compounds described in Table 1 represent the following:

[0299] "DiGMEMA": Diethylene glycol monomethyl ether methacrylate (hereinafter, refer to the structural formula)

[0300]

Chemistry 2

[0301]

[0302] "TeEDGDMA": Tetraethylene glycol dimethacrylate (hereinafter, refer to the structural formula)

[0303]

Transformation 3

[0304]

[0305] “PMEM”: Methoxylated polyethylene glycol methacrylate (hereinafter, refer to the structural formula. Mw: 500. n = 11)

[0306]

Chemistry 4

[0307]

[0308] “EGMMMA”: Ethylene glycol monoacetoacetate methacrylate (hereinafter, refer to the structural formula)

[0309]

Transformation 5

[0310]

[0311] “PEG1000”: Polyethylene glycol (hereinafter, refer to the structural formula. Mw: 1000. n = 23)

[0312]

Transformation 6

[0313]

[0314] "MPA": 2-Methyl-2-propenyl acetate (hereinafter, refer to the structural formula)

[0315]

Transformation 7

[0316]

[0317] In Table 1, the "parts by mass" column of the "compound" column indicates the amount of a specific polymer present in 100 parts by mass relative to the aqueous medium in Examples 1-5 and 7, and the amount of polyolefin oxide present in 100 parts by mass relative to the aqueous medium in Example 6.

[0318] In Table 1, the column “Amount of initiator used when polymerizing a specific compound” indicates the amount (g) of water-soluble polymerization initiator used when polymerizing a specific compound in Examples 1 to 5 and 7.

[0319] In Table 1, the "Solids content (%)" column indicates the concentration of solids in the aqueous dispersion of fluoropolymers.

[0320] In Table 1, the “D50(nm)” column represents the D50(nm) of the fluoropolymer particles.

[0321] In Table 1, "Q value (mm)" 3 The column " / g)" indicates the Q value (mm) of the fluoropolymer powder under a 50kg load. 3 / g).

[0322] In Table 1, the "Melting Point (°C)" column indicates the melting point (°C) of the fluoropolymer.

[0323] In Table 1, “TFE unit (mol%)”, “E unit (mol%)” and “PFBE unit (mol%)” represent the contents of TFE unit, E unit and PFBE unit in the obtained fluoropolymers, respectively.

[0324] In addition, in Examples 1 to 7, the emulsifier is practically absent when polymerizing fluorinated monomers.

[0325] [Table 1]

[0326]

[0327] As shown in Examples 1 to 7, the desired effect was confirmed to be achieved by the manufacturing method according to the present invention.

[0328] Furthermore, the entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2020-165490, filed on September 30, 2020, are incorporated herein by reference as disclosure of this invention.

Claims

1. A method for manufacturing a fluoropolymer, wherein the method uses an aqueous medium for emulsion polymerization, wherein, In an aqueous medium, a fluoropolymer is manufactured by polymerizing at least one fluorinated monomer selected from tetrafluoroethylene, trichlorofluoroethylene, and vinylidene fluoride in the presence of particles of a specific polymer comprising at least one unit selected from units of a compound represented by formula (1) and units of a compound represented by formula (2), wherein, when the tetrafluoroethylene is polymerized, the tetrafluoroethylene is copolymerized under conditions where the content of the tetrafluoroethylene-based unit in the fluoropolymer is less than 99% by mass relative to all units of the fluoropolymer. Equation (1): CXY = CR 1 -COO-(LO) n -R 2 Equation (2): CXY = CR 3 -(O) m -CH2-ZR 4 The symbols in equations (1) and (2) have the following meanings: X and Y independently represent hydrogen atoms, halogen atoms, or methyl groups. R 1 Indicates a hydrogen atom, a halogen atom, or an alkyl group having 1 to 3 carbon atoms. R 2 The group represents an alkyl group, an alkyl group in which at least one -CH2- is replaced by -CO-, or a group represented by formula (3) below. R 3 It represents hydrogen atoms, halogen atoms, alkyl groups having 1 to 3 carbon atoms, or -CO-OCH3. R 4 Indicates alkyl group, L indicates alkylene. Z represents -CO-O-* or -O-CO-*, where * indicates that it is related to R. 4 The bonding position, m represents 0 or 1, and n represents an integer greater than or equal to 1. Equation (3): -CO-CR 1 =CXY In equation (3), X, Y and R 1 respectively with X, Y and R in equation (1) 1 The definitions are the same.

2. The manufacturing method as described in claim 1, wherein, The amount of the specific polymer present is 0.0001 to 1.0 parts by mass relative to 100 parts by mass of the aqueous medium.

3. A method for manufacturing a fluoropolymer, wherein, At least one specific compound selected from compounds represented by formula (1) and formula (2) is polymerized in an aqueous medium to obtain an aqueous medium containing a specific polymer. Then, in the aqueous medium containing the specific polymer, at least one fluorinated monomer selected from tetrafluoroethylene, trichlorofluoroethylene, and vinylidene fluoride is polymerized to produce a fluoropolymer. In the case of polymerizing the tetrafluoroethylene, the tetrafluoroethylene is copolymerized under the condition that the content of tetrafluoroethylene-based units in the fluoropolymer is less than 99% by mass relative to all units of the fluoropolymer. Equation (1): CXY = CR 1 -COO-(LO) n -R 2 Equation (2): CXY = CR 3 -(O) m -CH2-ZR 4 The symbols in equations (1) and (2) have the following meanings: X and Y independently represent hydrogen atoms, halogen atoms, or methyl groups. R 1 Indicates a hydrogen atom, a halogen atom, or an alkyl group having 1 to 3 carbon atoms. R 2 The group represents an alkyl group, an alkyl group in which at least one -CH2- is replaced by -CO-, or a group represented by formula (3) below. R 3 It represents hydrogen atoms, halogen atoms, alkyl groups having 1 to 3 carbon atoms, or -CO-OCH3. R 4 Indicates alkyl group, L indicates alkylene. Z represents -CO-O-* or -O-CO-*, where * indicates that it is related to R. 4 The bonding position, m represents 0 or 1, and n represents an integer greater than or equal to 1. Equation (3): -CO-CR 1 =CXY In equation (3), X, Y and R 1 respectively with X, Y and R in equation (1) 1 The definitions are the same.

4. The manufacturing method as described in claim 3, wherein, The aqueous medium containing the specific polymer is an aqueous medium used for the manufacture of the specific polymer until the specific polymer is present.

5. The manufacturing method as described in claim 3 or 4, wherein, The amount of the specific polymer present in the polymerization of the fluorinated monomer is 0.0001 to 1.0 parts by mass relative to 100 parts by mass of the aqueous medium.

6. An aqueous dispersion of a fluoropolymer comprising an aqueous medium, particles having a volume-based cumulative 50% diameter of a fluoropolymer obtained by emulsion polymerization having units based on at least one fluorinated monomer selected from tetrafluoroethylene, trichlorofluoroethylene, and vinylidene fluoride, and having a diameter of 20–3000 nm, and a specific polymer having at least one unit selected from compounds represented by formula (1) and compounds represented by formula (2), wherein the specific polymer is contained as particles in the aqueous medium or in the particles containing the fluoropolymer, wherein, In the case where the fluoropolymer contains the tetrafluoroethylene-based units, the content of the tetrafluoroethylene-based units in the fluoropolymer is less than 99% by mass relative to all units of the fluoropolymer, and the aqueous dispersion is substantially free of emulsifiers. Equation (1): CXY = CR 1 -COO-(LO) n -R 2 Equation (2): CXY = CR 3 -(O) m -CH2-ZR 4 The symbols in equations (1) and (2) have the following meanings: X and Y independently represent hydrogen atoms, halogen atoms, or methyl groups. R 1 Indicates a hydrogen atom, a halogen atom, or an alkyl group having 1 to 3 carbon atoms. R 2 The group represents an alkyl group, an alkyl group in which at least one -CH2- is replaced by -CO-, or a group represented by formula (3) below. R 3 It represents hydrogen atoms, halogen atoms, alkyl groups having 1 to 3 carbon atoms, or -CO-OCH3. R 4 Indicates alkyl group, L indicates alkylene. Z represents -CO-O-* or -O-CO-*, where * indicates that it is related to R. 4 The bonding position, m represents 0 or 1, and n represents an integer greater than or equal to 1. Equation (3): -CO-CR 1 =CXY In equation (3), X, Y and R 1 respectively with X, Y and R in equation (1) 1 The definitions are the same.

7. The aqueous dispersion of the fluoropolymer as described in claim 6, wherein 1.0 to 50.0 parts by mass of the fluoropolymer-containing particles are contained in 100 parts by mass relative to the aqueous medium.

8. The aqueous dispersion of a fluoropolymer as claimed in claim 6 or 7, wherein 100 parts by mass of the aqueous medium contains 0.0001 to 1.0 parts by mass of particles of the particular polymer.

9. The aqueous dispersion of the fluoropolymer as claimed in claim 6, wherein 100 parts by mass of the fluoropolymer-containing particles comprise 0.001 to 5.00 parts by mass of the particles of the specific polymer.

10. A polymer composition comprising a fluoropolymer obtained by emulsion polymerization having units based on at least one fluorinated monomer selected from tetrafluoroethylene, trichlorofluoroethylene, and vinylidene fluoride, and a specific polymer having at least one unit selected from compounds represented by formula (1) and compounds represented by formula (2), wherein, In the case where the fluoropolymer contains the tetrafluoroethylene-based unit, the content of the tetrafluoroethylene-based unit in the fluoropolymer is less than 99% by mass relative to all units of the fluoropolymer, and the composition is substantially free of emulsifiers: Equation (1): CXY = CR 1 -COO-(LO) n -R 2 Equation (2): CXY = CR 3 -(O) m -CH2-ZR 4 The symbols in equations (1) and (2) have the following meanings: X and Y independently represent hydrogen atoms, halogen atoms, or methyl groups. R 1 Indicates a hydrogen atom, a halogen atom, or an alkyl group having 1 to 3 carbon atoms. R 2 The group represents an alkyl group, an alkyl group in which at least one -CH2- is replaced by -CO-, or a group represented by formula (3) below. R 3 It represents hydrogen atoms, halogen atoms, alkyl groups having 1 to 3 carbon atoms, or -CO-OCH3. R 4 Indicates alkyl group, L indicates alkylene. Z represents -CO-O-* or -O-CO-*, where * indicates that it is related to R. 4 The bonding position, m represents 0 or 1, and n represents an integer greater than or equal to 1. Equation (3): -CO-CR 1 =CXY In equation (3), X, Y and R 1 respectively with X, Y and R in equation (1) 1 The definitions are the same.

11. The polymer composition of claim 10, wherein, The content of the specific polymer relative to 100 parts by weight of the fluoropolymer is 0.001 to 5.00 parts by weight.

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