Fluoropolymer and method for producing same

Abstract

Provided is a method for producing a fluoropolymer in which a fluoropolymer comprising a monomer (I), which is represented by general formula (I), by carrying out polymerization of the monomer (I) in an aqueous medium, and the oxygen concentration in the polymerization reaction system is maintained at 500 volume ppm or less.　General formula (I): CX2=CY–CF2–O–Rf–A (In the formula, X and Y are independently H, F, CH3 or CF3, and at least one of X and Y is F). Rf represents a C1-40 fluorine-containing alkylene group or a C2-100 fluorine-containing alkylene group having an ether bond. A represents –COOM, –SO3M, –OSO3M or –C(CF3)2OM (wherein M represents H, a metal atom, NR7 4, an optionally substituted imidazolium, an optionally substituted pyridinium or an optionally substituted phosphonium; and R7 represents H or an organic group).

Description

[Technical field]

[0001] The present disclosure relates to fluoropolymers and methods for making the same. [Background technology]

[0002] Patent Document 1 describes a coating composition that is particularly preferable for more effectively and efficiently obtaining an anti-reflective film on a resist film, as follows: (A1) Fluorine-containing polymer having a carboxyl group (B) at least one solvent selected from the group consisting of water and alcohols A composition consisting of: The fluorine-containing polymer (A1) is represented by the formula (M-3): -(M3)-(N3)- (M-3) [wherein the structural unit M3 is represented by the formula (5): [ka] (In the formula, X 10 , X 11 are the same or different H or F;X 12 is H, F, Cl, CH3 or CF3;X 13 , X 14 are the same or different H or F; Rf 10 a1 and c1 are the same or different and are structural units derived from a fluorine-containing monomer represented by 0 or 1); the structural unit N3 is a structural unit derived from a monomer copolymerizable with the fluorine-containing monomer of the formula (5), and the coating composition is a fluorine-containing polymer containing 55 to 100 mol % of the structural unit M3 and 0 to 45 mol % of the structural unit N3 and having a number average molecular weight of 10,000 to 750,000. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2005 / 050320 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure aims to provide a production method capable of producing a fluoropolymer having a high molecular weight even when a large amount of polymerization units based on a monomer having a specific structure is introduced into the fluoropolymer.

[0005] Another object of the present disclosure is to provide a fluoropolymer that can easily form a uniform coating film having a desired thickness despite containing a large amount of polymerization units based on a monomer having a specific structure. [Means for solving the problem]

[0006] According to the present disclosure, there is provided a method for producing a fluoropolymer of monomer (I) by polymerizing monomer (I) represented by general formula (I) in an aqueous medium, wherein the oxygen concentration in the polymerization reaction system is maintained at 500 ppm by volume or less. General formula (I): CX2=CY-CF2-O-Rf-A (In the formula, X and Y are independently H, F, CH3 or CF3, and at least one of X and Y is F. Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. A is -COOM, -SO3M, -OSO3M or -C(CF3)2OM (M is H, a metal atom, NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group.

[0007] In the production method of the present disclosure, the polymerization of the monomer (I) is preferably carried out at a polymerization temperature of 20°C to 59°C. In the production method of the present disclosure, it is preferable that the polymerization of the monomer (I) is carried out in the presence of a polymerization initiator, and the polymerization initiator is a persulfate. In the production method according to the present disclosure, it is preferable that the polymerization of the monomer (I) is carried out in the presence of a polymerization initiator, and the total amount of the polymerization initiator used in the polymerization is 0.00001 to 10% by mass with respect to the aqueous medium. In the production method of the present disclosure, the amount of monomers containing monomer (I) present at the start of polymerization is preferably 40 mass % or more relative to the amount of the aqueous medium present. In the production method of the present disclosure, the content of polymerized units (I) based on monomer (I) in the fluoropolymer is preferably 50 mol % or more based on all polymerized units constituting the fluoropolymer. In the production method of the present disclosure, the content of polymerized units (I) based on monomer (I) in the fluoropolymer is preferably 99 mol % or more based on all polymerized units constituting the fluoropolymer. In the manufacturing method of the present disclosure, the weight average molecular weight (Mw) of the fluoropolymer is 20.0 × 10 4 It is preferable that the value is 38.0×10 or more. 4 More preferably, it is equal to or greater than this. In the manufacturing method of the present disclosure, the number average molecular weight (Mn) of the fluoropolymer is 8.0 × 10 4 More preferably, it is equal to or greater than this. In the production method of the present disclosure, it is preferable to produce an aqueous solution containing the fluoropolymer. In the production method of the present disclosure, after the polymerization is completed, the composition containing the aqueous medium and the fluoropolymer is recovered, and the composition is preferably treated by at least one means selected from the group consisting of ultrafiltration, microfiltration, dialysis membrane treatment, liquid separation and reprecipitation.

[0008] According to the present disclosure, there is provided a fluoropolymer of a monomer (I) represented by general formula (I), in which the content of the polymerization units (I) based on the monomer (I) is 50 mol% or more relative to the total polymerization units constituting the fluoropolymer, and the weight average molecular weight (Mw) is 38.0 × 10 4 Thus, a fluoropolymer is provided. General formula (I): CX2=CY-CF2-O-Rf-A (In the formula, X and Y are independently H, F, CH3 or CF3, and at least one of X and Y is F. Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. A is -COOM, -SO3M, -OSO3M or -C(CF3)2OM (M is H, a metal atom, NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group.

[0009] The fluoropolymer of the present disclosure has a number average molecular weight (Mn) of 8.0×10 4 More preferably, it is equal to or greater than this. In the fluoropolymer of the present disclosure, the content of polymerized units (I) is preferably 99 mol % or more based on all polymerized units constituting the fluoropolymer. The fluoropolymers of the present disclosure are preferably substantially free of dimers and trimers of monomer (I).

[0010] The present disclosure also provides an aqueous solution containing the above-described fluoropolymer.

[0011] In the aqueous solution of the present disclosure, the content of the fluoropolymer is preferably 2% by mass or more relative to the aqueous solution.

[0012] The present disclosure also provides a coating composition containing the above-mentioned fluoropolymer or the above-mentioned aqueous solution. Effect of the Invention

[0013] According to the present disclosure, it is possible to provide a production method capable of producing a fluoropolymer having a high molecular weight even when a large amount of polymerization units based on a monomer having a specific structure is introduced into the fluoropolymer.

[0014] In addition, according to the present disclosure, it is possible to provide a fluoropolymer that can easily form a uniform coating film having a desired thickness despite containing a large amount of polymerization units based on a monomer having a specific structure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Specific embodiments of the present disclosure will be described in detail below, but the present disclosure is not limited to the following embodiments.

[0016] Before specifically describing the present disclosure, some terms used in the present disclosure will be defined or explained.

[0017] In this disclosure, "organic group" means a group containing one or more carbon atoms or a group formed by removing a hydrogen atom from an organic compound. Examples of the "organic group" are: an alkyl group which may have one or more substituents; an alkenyl group optionally having one or more substituents; an alkynyl group optionally having one or more substituents; a cycloalkyl group optionally having one or more substituents, a cycloalkenyl group optionally having one or more substituents, a cycloalkadienyl group optionally having one or more substituents, an aryl group which may have one or more substituents; an aralkyl group optionally having one or more substituents; a non-aromatic heterocyclic group optionally having one or more substituents, a heteroaryl group optionally having one or more substituents, Cyano group, Formyl group, RaO-, RaCO-, RaSO2-, RaCOO-, RaNRaCO-, RaCONRa-, RaOCO-, RaOSO2-, and RaNRbSO2- (In these formulas, Ra is independently an alkyl group which may have one or more substituents; an alkenyl group optionally having one or more substituents; an alkynyl group optionally having one or more substituents; a cycloalkyl group optionally having one or more substituents, a cycloalkenyl group optionally having one or more substituents, a cycloalkadienyl group optionally having one or more substituents, an aryl group which may have one or more substituents; an aralkyl group optionally having one or more substituents; a non-aromatic heterocyclic group optionally having one or more substituents, or a heteroaryl group optionally having one or more substituents, Rb is independently H or an alkyl group which may have one or more substituents. Includes: The organic group is preferably an alkyl group which may have one or more substituents.

[0018] In the present disclosure, a "substituent" means a substitutable group. Examples of the "substituent" include an aliphatic group, an aromatic group, a heterocyclic group, an acyl group, an acyloxy group, an acylamino group, an aliphatic oxy group, an aromatic oxy group, a heterocyclic oxy group, an aliphatic oxycarbonyl group, an aromatic oxycarbonyl group, a heterocyclic oxycarbonyl group, a carbamoyl group, an aliphatic sulfonyl group, an aromatic sulfonyl group, a heterocyclic sulfonyl group, an aliphatic sulfonyloxy group, an aromatic sulfonyloxy group, a heterocyclic sulfonyloxy group, a sulfamoyl group, an aliphatic sulfonamide group, an aromatic sulfonamide group, a heterocyclic sulfonamide group, an amino group, an aliphatic amino These include an aromatic amino group, an aromatic amino group, a heterocyclic amino group, an aliphatic oxycarbonylamino group, an aromatic oxycarbonylamino group, a heterocyclic oxycarbonylamino group, an aliphatic sulfinyl group, an aromatic sulfinyl group, an aliphatic thio group, an aromatic thio group, a hydroxy group, a cyano group, a sulfo group, a carboxy group, an aliphatic oxyamino group, an aromatic oxyamino group, a carbamoylamino group, a sulfamoylamino group, a halogen atom, a sulfamoylcarbamoyl group, a carbamoylsulfamoyl group, a dialiphatic oxyphosphinyl group, and a diaromatic oxyphosphinyl group.

[0019] The aliphatic group may be saturated or unsaturated, and may have a hydroxy group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aliphatic group include alkyl groups having a total of 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms, such as a methyl group, an ethyl group, a vinyl group, a cyclohexyl group, and a carbamoylmethyl group.

[0020] The aromatic group may have, for example, a nitro group, a halogen atom, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aromatic group include aryl groups having 6 to 12 carbon atoms, preferably 6 to 10 carbon atoms in total, such as a phenyl group, a 4-nitrophenyl group, a 4-acetylaminophenyl group, and a 4-methanesulfonylphenyl group.

[0021] The heterocyclic group may have a halogen atom, a hydroxy group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the heterocyclic group include a 5- or 6-membered heterocycle having a total of 2 to 12, preferably 2 to 10, carbon atoms, such as a 2-tetrahydrofuryl group and a 2-pyrimidyl group.

[0022] The acyl group may have an aliphatic carbonyl group, an arylcarbonyl group, a heterocyclic carbonyl group, a hydroxy group, a halogen atom, an aromatic group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the acyl group include acyl groups having a total of 2 to 8 carbon atoms, preferably 2 to 4 carbon atoms, such as an acetyl group, a propanoyl group, a benzoyl group, and a 3-pyridinecarbonyl group.

[0023] The acylamino group may have an aliphatic group, an aromatic group, a heterocyclic group, etc., such as an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc. Examples of the acylamino group include an acylamino group having a total of 2 to 12 carbon atoms, preferably 2 to 8 carbon atoms, and an alkylcarbonylamino group having a total of 2 to 8 carbon atoms, such as an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc.

[0024] The aliphatic oxycarbonyl group may be saturated or unsaturated, and may have a hydroxy group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aliphatic oxycarbonyl group include alkoxycarbonyl groups having a total of 2 to 8 carbon atoms, preferably 2 to 4 carbon atoms, such as a methoxycarbonyl group, an ethoxycarbonyl group, and a (t)-butoxycarbonyl group.

[0025] The carbamoyl group may have an aliphatic group, an aromatic group, a heterocyclic group, etc. Examples of the carbamoyl group include an unsubstituted carbamoyl group, an alkylcarbamoyl group having a total of 2 to 9 carbon atoms, preferably an unsubstituted carbamoyl group, an alkylcarbamoyl group having a total of 2 to 5 carbon atoms, such as an N-methylcarbamoyl group, an N,N-dimethylcarbamoyl group, and an N-phenylcarbamoyl group.

[0026] The aliphatic sulfonyl group may be saturated or unsaturated, and may have a hydroxy group, an aromatic group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aliphatic sulfonyl group include alkylsulfonyl groups having a total of 1 to 6 carbon atoms, preferably a total of 1 to 4 carbon atoms, such as a methanesulfonyl group.

[0027] The aromatic sulfonyl group may have a hydroxy group, an aliphatic group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aromatic sulfonyl group include arylsulfonyl groups having a total of 6 to 10 carbon atoms, such as a benzenesulfonyl group.

[0028] The amino group may have an aliphatic group, an aromatic group, a heterocyclic group, or the like.

[0029] The acylamino group may have, for example, an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc. Examples of the acylamino group include an acylamino group having a total of 2 to 12 carbon atoms, preferably a total of 2 to 8 carbon atoms, and more preferably an alkylcarbonylamino group having a total of 2 to 8 carbon atoms, such as an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc.

[0030] The aliphatic sulfonamide group, aromatic sulfonamide group, and heterocyclic sulfonamide group may be, for example, a methanesulfonamide group, a benzenesulfonamide group, or a 2-pyridinesulfonamide group.

[0031] The sulfamoyl group may have an aliphatic group, an aromatic group, a heterocyclic group, etc. Examples of the sulfamoyl group include a sulfamoyl group, an alkylsulfamoyl group having a total of 1 to 9 carbon atoms, a dialkylsulfamoyl group having a total of 2 to 10 carbon atoms, an arylsulfamoyl group having a total of 7 to 13 carbon atoms, and a heterocyclic sulfamoyl group having a total of 2 to 12 carbon atoms, more preferably a sulfamoyl group, an alkylsulfamoyl group having a total of 1 to 7 carbon atoms, a dialkylsulfamoyl group having a total of 3 to 6 carbon atoms, an arylsulfamoyl group having a total of 6 to 11 carbon atoms, and a heterocyclic sulfamoyl group having a total of 2 to 10 carbon atoms, such as a sulfamoyl group, a methylsulfamoyl group, an N,N-dimethylsulfamoyl group, a phenylsulfamoyl group, and a 4-pyridine sulfamoyl group.

[0032] The aliphatic oxy group may be saturated or unsaturated and may have a methoxy group, an ethoxy group, an i-propyloxy group, a cyclohexyloxy group, a methoxyethoxy group, etc. Examples of the aliphatic oxy group include alkoxy groups having a total of 1 to 8 carbon atoms, preferably 1 to 6 carbon atoms, such as a methoxy group, an ethoxy group, an i-propyloxy group, a cyclohexyloxy group, a methoxyethoxy group, etc.

[0033] The aromatic amino group and heterocyclic amino group may have an aliphatic group, an aliphatic oxy group, a halogen atom, a carbamoyl group, a heterocyclic group condensed with the aryl group, or an aliphatic oxycarbonyl group, preferably an aliphatic group having 1 to 4 carbon atoms in total, an aliphatic oxy group having 1 to 4 carbon atoms in total, a halogen atom, a carbamoyl group having 1 to 4 carbon atoms in total, a nitro group, or an aliphatic oxycarbonyl group having 2 to 4 carbon atoms in total.

[0034] The aliphatic thio group may be saturated or unsaturated and is an alkylthio group having a total of 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, such as a methylthio group, an ethylthio group, a carbamoylmethylthio group, or a t-butylthio group.

[0035] The carbamoylamino group may have an aliphatic group, an aryl group, a heterocyclic group, etc. Examples of the carbamoylamino group include a carbamoylamino group, an alkylcarbamoylamino group having a total of 2 to 9 carbon atoms, a dialkylcarbamoylamino group having a total of 3 to 10 carbon atoms, an arylcarbamoylamino group having a total of 7 to 13 carbon atoms, and a heterocyclic carbamoylamino group having a total of 3 to 12 carbon atoms, preferably a carbamoylamino group, an alkylcarbamoylamino group having a total of 2 to 7 carbon atoms, a dialkylcarbamoylamino group having a total of 3 to 6 carbon atoms, an arylcarbamoylamino group having a total of 7 to 11 carbon atoms, and a heterocyclic carbamoylamino group having a total of 3 to 10 carbon atoms, such as a carbamoylamino group, a methylcarbamoylamino group, an N,N-dimethylcarbamoylamino group, a phenylcarbamoylamino group, and a 4-pyridinecarbamoylamino group.

[0036] In this disclosure, ranges expressed by endpoints include all numbers subsumed within that range (eg, 1 to 10 includes 1.4, 1.9, 2.33, 5.75, 9.98, etc.).

[0037] In this disclosure, the term "at least 1" includes all numbers greater than or equal to 1 (e.g., at least 2, at least 4, at least 6, at least 8, at least 10, at least 25, at least 50, at least 100, etc.).

[0038] Next, the manufacturing method of the present disclosure will be specifically described.

[0039] The production method of the present disclosure is a method for producing a fluoropolymer by polymerizing a monomer (I) represented by general formula (I) to produce a fluoropolymer of the monomer (I). General formula (I): CX2=CY-CF2-O-Rf-A (In the formula, X and Y are independently H, F, CH3 or CF3, and at least one of X and Y is F. Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. A is -COOM, -SO3M, -OSO3M or -C(CF3)2OM (M is H, a metal atom, NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group.

[0040] In the manufacturing method of the present disclosure, when the monomer (I) is polymerized, the oxygen concentration in the polymerization reaction system is maintained at 500 volume ppm or less. By selecting such polymerization conditions, the molecular weight of the fluoropolymer of the monomer (I) can be increased.

[0041] In the conventional manufacturing method, when it was attempted to introduce a large amount of polymerization units (I) based on the monomer (I) into the fluoropolymer, it was not possible to produce a fluoropolymer having a high molecular weight. According to the manufacturing method disclosed herein, it is possible to introduce 50 mol % or more of the polymerization units (I) with respect to the total polymerization units constituting the fluoropolymer, and at the same time, to increase the weight average molecular weight (Mw) of the fluoropolymer to 38.0×10 4 It can be increased to more than that.

[0042] The oxygen concentration in the polymerization reaction system is 500 ppm by volume or less. In the production method of the present disclosure, the oxygen concentration in the reaction system is maintained at 500 ppm by volume or less throughout the entire polymerization period of the monomer (I). The oxygen concentration in the reaction system is preferably 350 ppm by volume or less, more preferably 300 ppm by volume or less, even more preferably 100 ppm by volume or less, and particularly preferably 50 ppm by volume or less. In addition, the oxygen concentration in the reaction system is usually 0.01 ppm by volume or more.

[0043] The oxygen concentration in the polymerization reaction system can be controlled, for example, by circulating an inert gas such as nitrogen or argon, or, when a gaseous monomer is used, the gaseous monomer in the reaction liquid or in the gas phase surrounding the reaction liquid. The oxygen concentration in the polymerization reaction system can be determined by measuring and analyzing the gas coming out of the exhaust gas line of the polymerization system with a low-concentration oxygen analyzer.

[0044] The polymerization temperature of the monomer (I) is preferably 59°C or lower, more preferably 57°C or lower, even more preferably 55°C or lower, and particularly preferably 53°C or lower, and is preferably 20°C or higher, preferably 25°C or higher, more preferably 30°C or higher, and particularly preferably 35°C or higher, because this facilitates the production of a fluoropolymer having a higher molecular weight.

[0045] In the production method of the present disclosure, the polymerization may be carried out in the presence of a pH adjuster. The pH adjuster may be added before or after the initiation of the polymerization.

[0046] Examples of pH adjusters that can be used include ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, ammonium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, ammonium hydrogen carbonate, sodium phosphate, potassium phosphate, sodium citrate, potassium citrate, ammonium citrate, sodium gluconate, potassium gluconate, ammonium gluconate, etc. The pH can be measured using a pH meter manufactured by Orion.

[0047] The polymerization pressure is usually from atmospheric pressure to 10 MPaG and is appropriately determined depending on the type of monomer used, the molecular weight of the desired fluoropolymer, and the reaction rate.

[0048] The polymerization time is usually from 1 to 200 hours, and may be from 5 to 100 hours.

[0049] The aqueous medium is a reaction medium for polymerization, and refers to a liquid containing water. The aqueous medium is not particularly limited as long as it contains water, and may contain water and, for example, a fluorine-free organic solvent such as alcohol, ether, or ketone, and / or a fluorine-containing organic solvent having a boiling point of 40° C. or less. Water is preferable as the aqueous medium.

[0050] The monomer (I) is represented by the general formula (I). General formula (I): CX2=CY-CF2-O-Rf-A

[0051] In the formula, X and Y are independently H, F, CH3 or CF3, and at least one of X and Y is F. X is preferably H or F, and more preferably H. Y is preferably H or F, and more preferably F.

[0052] In the formula, Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, or a fluorine-containing alkylene group having an ether bond having 2 to 100 carbon atoms. The fluorine-containing alkylene group having an ether bond having 2 to 100 carbon atoms is an alkylene group that does not include a structure in which an oxygen atom is at the terminal and contains an ether bond between carbon atoms.

[0053] The number of carbon atoms in the fluorine-containing alkylene group is preferably 2 or more. The number of carbon atoms in the fluorine-containing alkylene group is preferably 30 or less, more preferably 20 or less, even more preferably 10 or less, particularly preferably 6 or less, and most preferably 3 or less. Examples of the fluorine-containing alkylene group include -CF2-, -CH2CF2-, -CF2CF2-, -CF2CF2CF2-, -CF2CH2-, -CF2CF2CH2-, -CF(CF3)-, -CF(CF3)CF2-, and -CF(CF3)CH2-. The fluorine-containing alkylene group is preferably a perfluoroalkylene group.

[0054] The number of carbon atoms in the fluorine-containing alkylene group having an ether bond is preferably 3 or more. The number of carbon atoms in the fluorine-containing alkylene group having an ether bond is preferably 60 or less, more preferably 30 or less, further preferably 12 or less, particularly preferably 9 or less, and most preferably 6 or less. The fluorine-containing alkylene group having an ether bond is, for example, a group represented by the general formula: [ka] (In the formula, Z 1 is F or CF3;Z 2 and Z 3 are H or F;Z respectively 4 is H, F, or CF3; p1+q1+r1 is an integer of 1 to 10; s1 is 0 or 1; and t1 is an integer of 0 to 5).

[0055] Specific examples of the fluorine-containing alkylene group having an ether bond include -CF(CF3)CF2-O-CF(CF3)-, -(CF(CF3)CF2-O) n-CF(CF3)- (wherein n is an integer of 1 to 10), -CF(CF3)CF2-O-CF(CF3)CH2-, -(CF(CF3)CF2-O) n Examples include -CF(CF3)CH2- (wherein n is an integer of 1 to 10), -CH2CF2CF2O-CH2CF2CH2-, -CF2CF2CF2O-CF2CF2-, -CF2CF2CF2O-CF2CF2CH2-, -CF2CF2O-CF2-, -CF2CF2O-CF2CH2-, etc. The fluorine-containing alkylene group having an ether bond is preferably a perfluoroalkylene group.

[0056] In the formula, A is -COOM, -SO3M, -OSO3M or -C(CF3)2OM. As A, -COOM or -SO3M is preferable, and -COOM is more preferable.

[0057] M is H, a metal atom, or NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group.

[0058] The metal atom includes alkali metals (Group 1), alkaline earth metals (Group 2), etc., and is preferably Na, K or Li.

[0059] M is H, a metal atom, or NR 7 4 is preferred, H, an alkali metal (group 1), an alkaline earth metal (group 2) or NR 7 R is more preferably 4, more preferably H, Na, K, Li or NH4, even more preferably H, Na, K or NH4, particularly preferably H, Na or NH4, and most preferably H or NH4. 7 As for the 1-10 is preferably an organic group represented by the formula: 1-4 More preferred is an organic group of H or C 1-4 More preferred are alkyl groups of the formula:

[0060] The monomer (I) is preferably a monomer represented by the general formula (1A). The polymerized units (I) are preferably polymerized units (1A) based on a monomer represented by general formula (1A). CH2=CF(-CF2-O-Rf-A) (1A) (In the formula, Rf and A are the same as above.)

[0061] In the production method of the present disclosure, the monomer represented by general formula (1A) may be copolymerized with other monomers. The fluoropolymer may be a homopolymer of the monomer represented by the general formula (1A) or a copolymer with other monomers.

[0062] Specific examples of the monomer represented by formula (1A) include those represented by the general formula:

[0063] [ka]

[0064] (In the formula, Z 1 is F or CF3;Z 2 and Z 3 are H or F;Z respectively 4 is H, F or CF3; p1+q1+r1 are integers from 0 to 10; s1 is 0 or 1; t1 is an integer from 0 to 5, except for Z 3 and Z 4 are both H, then p1+q1+r1+s1 is not 0; A is as defined above). More specifically,

[0065] [ka]

[0066] The following are preferred:

[0067] [ka]

[0068] It is preferable that:

[0069] As the monomer represented by general formula (1A), it is preferable that A in formula (1A) is -COOM, and in particular, at least one selected from the group consisting of CH2=CFCF2OCF(CF3)COOM and CH2=CFCF2OCF(CF3)CF2OCF(CF3)COOM (wherein M is as defined above) is preferable, and CH2=CFCF2OCF(CF3)COOM is more preferable.

[0070] Further, examples of the monomer represented by the general formula (I) include the monomer represented by the following formula: CF2=CFCF2-O-Rf-A (wherein Rf and A are the same as above)

[0071] More specifically, [ka] etc.

[0072] In the production method of the present disclosure, the monomer (I) may be copolymerized with other monomers. The fluoropolymer may be a homopolymer of the monomer represented by general formula (I) or a copolymer with other monomers.

[0073] As the other monomer, a monomer represented by the general formula CFR=CR2 (wherein R is independently H, F or a perfluoroalkyl group having 1 to 4 carbon atoms) is preferred. In addition, as the other monomer, a fluorine-containing ethylenic monomer having 2 or 3 carbon atoms is preferred. Examples of the other monomer include CF2=CF2, CF2=CFCl, CH2=CF2, CFH=CH2, CFH=CF2, CF2=CFCF3, CH2=CFCF3, CH2=CHCF3, CHF=CHCF3 (E form), CHF=CHCF3 (Z form), etc.

[0074] As the other monomer, in particular, at least one selected from the group consisting of tetrafluoroethylene (CF2=CF2), chlorotrifluoroethylene (CF2=CFCl) and vinylidene fluoride (CH2=CF2) is preferred in terms of good copolymerizability, and at least one selected from the group consisting of tetrafluoroethylene and vinylidene fluoride is more preferred. Therefore, the polymerization units based on the other monomer are preferably polymerization units based on tetrafluoroethylene. The polymerization units based on the other monomer may be the same or different in each occurrence, and the fluoropolymer may contain polymerization units based on two or more different other monomers.

[0075] As the other monomer, there is also a monomer represented by the general formula (n1-2):

[0076] [ka]

[0077] (In the formula, X 1 , X 2 are the same or different H or F;X 3 is H, F, Cl, CH3 or CF3;X 4 , X 5 are the same or different and are H or F; a and c are the same or different and are 0 or 1. Rf 3 is a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having ether bonds having 2 to 100 carbon atoms).

[0078] Specifically, CH2=CFCF2-O-Rf 3 , CF2=CF-O-Rf 3 , CF2=CFCF2-O-Rf 3 , CF2=CF-Rf 3 , CH2=CH-Rf 3 , CH2=CH-O-Rf 3 (In the formula, Rf 3 is the same as the above formula (n1-2)).

[0079] As the other monomer, there may be mentioned a monomer represented by the formula (n2-1):

[0080] [ka]

[0081] (In the formula, X 9 is H, F or CH3; Rf 4 Also included are fluorine-containing acrylate monomers represented by Rf (a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having 2 to 100 carbon atoms and an ether bond). 4 The base is

[0082] [ka]

[0083] (wherein d3 is an integer of 1 to 4; e3 is an integer of 1 to 10), etc. can be mentioned.

[0084] As the other monomer, there may be mentioned a monomer represented by the formula (n2-2): CH2=CHO-Rf 5 (n2-2) (In the formula, Rf 5 Also included are fluorine-containing vinyl ethers represented by the formula (I) (a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having 2 to 100 carbon atoms and having an ether bond).

[0085] Specific examples of the monomer of general formula (n2-2) include:

[0086] [ka]

[0087] (wherein e6 is an integer of 1 to 10) are preferred.

[0088] More specifically,

[0089] [ka]

[0090] etc.

[0091] Others, general formula (n2-3): CH2=CHCH2O-Rf 6 (n2-3) (In the formula, Rf 6 is a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having an ether bond having 2 to 100 carbon atoms), a fluorine-containing allyl ether represented by the general formula (n2-4): CH2=CH-Rf 7 (n2-4) (In the formula, Rf 7 Also included are fluorine-containing vinyl monomers represented by the formula (I) being a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having 2 to 100 carbon atoms and having an ether bond.

[0092] Specific examples of the monomers represented by the general formulas (n2-3) and (n2-4) include:

[0093] [ka]

[0094] and the like monomers.

[0095] In the manufacturing method of the present disclosure, the polymerization of the monomer (I) can be carried out in the presence of a polymerization initiator. The polymerization initiator is not particularly limited as long as it can generate radicals in the above-mentioned polymerization temperature range, and known oil-soluble and / or water-soluble polymerization initiators can be used. Furthermore, it can also be combined with a reducing agent or the like to initiate polymerization as a redox. The concentration of the polymerization initiator is appropriately determined depending on the type of monomer, the molecular weight of the target fluoropolymer, and the reaction rate.

[0096] As the polymerization initiator, persulfates (e.g., ammonium persulfate), disuccinic acid peroxide, diglutaric acid peroxide, and other organic peroxides can be used alone or in the form of a mixture thereof. They may also be used in combination with a reducing agent such as sodium sulfite to form a redox system. Furthermore, during polymerization, a radical scavenger such as hydroquinone or catechol, or a peroxide decomposer such as ammonium sulfite, can be added to adjust the radical concentration in the system.

[0097] As the polymerization initiator, a persulfate is particularly preferred because it can easily produce a fluoropolymer having a higher molecular weight. Examples of the persulfate include ammonium persulfate, potassium persulfate, and sodium persulfate, and ammonium persulfate is preferred.

[0098] The amount of polymerization initiator to be added is not particularly limited, but may be added all at once, stepwise, or continuously in an amount (for example, several ppm relative to water concentration) at least at which the polymerization rate does not drop significantly. The upper limit is a range in which the reaction temperature may be increased while removing heat from the equipment side by the polymerization reaction heat, and a more preferable upper limit is a range in which the polymerization reaction heat can be removed from the equipment side.

[0099] In the manufacturing method of the present disclosure, the polymerization initiator can be added at the start of polymerization and during polymerization. When the polymerization initiator is added during polymerization, the ratio of the amount of polymerization initiator added at the start of polymerization to the amount of polymerization initiator added during polymerization is preferably 95 / 5 to 5 / 95, more preferably 60 / 40 to 10 / 90, and further preferably 30 / 70 to 15 / 85. The method of adding the polymerization initiator during polymerization is not particularly limited, and the entire amount may be added at once, or may be added in two or more portions, or may be added continuously.

[0100] In the production method of the present disclosure, since a fluoropolymer having a higher molecular weight can be easily produced, the total amount of polymerization initiators used in the polymerization is preferably 0.00001 to 10% by mass relative to the aqueous medium. The total amount of polymerization initiators used in the polymerization is preferably 0.0001% by mass or more, more preferably 0.001% by mass or more, and even more preferably 0.01% by mass or more, and is preferably 5% by mass or less, and more preferably 2% by mass or less.

[0101] In the manufacturing method of the present disclosure, since a fluoropolymer having a higher molecular weight can be easily manufactured, the amount of monomers containing monomer (I) present at the start of polymerization is preferably 30% by mass or more relative to the amount of aqueous medium present. The amount of monomer present is more preferably 35% by mass or more, and even more preferably 40% by mass or more. The upper limit of the amount of monomer present is not particularly limited, but may be 70% by mass or less, or 60% by mass or less, from the viewpoint of smoothly proceeding with polymerization. The amount of monomer present at the start of polymerization is the total amount of monomer (I) and other monomers, if any, present in the reactor at the start of polymerization.

[0102] The polymerization of the monomer (I) can be carried out by charging an aqueous medium, the monomer (I), and, if necessary, other monomers and, if necessary, other additives into a reactor, stirring the contents of the reactor, maintaining the reactor at a predetermined polymerization temperature, and then adding a predetermined amount of a polymerization initiator to start the polymerization reaction. After the start of the polymerization reaction, the monomer, the polymerization initiator, and other additives may be added depending on the purpose.

[0103] The polymerization of the monomer (I) can be carried out substantially in the absence of a fluorine-containing surfactant. In the present disclosure, "substantially in the absence of a fluorine-containing surfactant" means that the amount of the fluorine-containing surfactant relative to the aqueous medium is 10 mass ppm or less. The amount of the fluorine-containing surfactant relative to the aqueous medium is preferably 1 mass ppm or less, more preferably 100 mass ppb or less, even more preferably 10 mass ppb or less, and even more preferably 1 mass ppb or less.

[0104] The above-mentioned fluorine-containing surfactant may be an anionic fluorine-containing surfactant, etc. The above-mentioned anionic fluorine-containing surfactant may be, for example, a surfactant containing fluorine atoms having a total carbon number of 20 or less excluding the anionic group.

[0105] The above-mentioned fluorine-containing surfactant may also be a surfactant containing fluorine in the anionic moiety having a molecular weight of 800 or less. The above-mentioned "anionic portion" refers to the portion of the above-mentioned fluorine-containing surfactant excluding the cation. For example, F(CF2) represented by the formula (I) described below n1 In the case of COOM, "F(CF2) n1 The "COO" part.

[0106] The above-mentioned fluorosurfactant also includes a fluorosurfactant having a LogPOW of 3.5 or less. The LogPOW is a partition coefficient between 1-octanol and water, and is expressed as LogP [wherein P represents the ratio of the fluorosurfactant concentration in octanol to the fluorosurfactant concentration in water when a 1:1 octanol / water mixture containing the fluorosurfactant undergoes phase separation]. The LogPOW is calculated from the HPLC elution time of the sample solution using a calibration curve of each elution time and the known octanol / water partition coefficient, which is prepared by performing HPLC on standard substances (heptanoic acid, octanoic acid, nonanoic acid, and decanoic acid) having known octanol / water partition coefficients under the following conditions: column: TOSOH ODS-120T column (φ4.6 mm×250 mm, manufactured by Tosoh Corporation), eluent: acetonitrile / 0.6% by mass HClO4 water=1 / 1 (vol / vol%), flow rate: 1.0 ml / min, sample amount: 300 μL, column temperature: 40° C., and detection light: UV 210 nm.

[0107] Specific examples of the fluorine-containing surfactant include those described in U.S. Patent Application Publication No. 2007 / 0015864, U.S. Patent Application Publication No. 2007 / 0015865, U.S. Patent Application Publication No. 2007 / 0015866, U.S. Patent Application Publication No. 2007 / 0276103, U.S. Patent Application Publication No. 2007 / 0117914, U.S. Patent Application Publication No. 2007 / 142541, U.S. Patent Application Publication No. 2008 / 0015319, U.S. Patent No. 3,250,808, and the like. No. 3,271,341, JP 2003-119204 A, WO 2005 / 042593 A, WO 2008 / 060461 A, WO 2007 / 046377 A, JP 2007-119526 A, WO 2007 / 046482 A, WO 2007 / 046345 A, U.S. Patent Application Publication No. 2014 / 0228531 A, WO 2013 / 189824 A, and WO 2013 / 189826 A can be mentioned.

[0108] The anionic fluorine-containing surfactant may be a surfactant represented by the following general formula (N 0 ): X n0 -Rf n0 -Y 0 (N 0 ) (In the formula, X n0 is H, Cl or F. n0 Y is a linear, branched or cyclic alkylene group having 3 to 20 carbon atoms, in which some or all of the H's are substituted with F, and the alkylene group may contain one or more ether bonds, and some of the H's may be substituted with Cl. 0 is an anionic group. Y 0 The anionic group may be -COOM, -SO2M, or -SO3M, and may be -COOM or -SO3M. M is H, a metal atom, or NR 7 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 7is H or an organic group. The metal atom includes alkali metals (Group 1), alkaline earth metals (Group 2), etc., such as Na, K, or Li. R 7 As the 1-10 may be an organic group of H or C 1-4 may be an organic group of H or C 1-4 The alkyl group may be: M is H, a metal atom or NR 7 4, H, an alkali metal (group 1), an alkaline earth metal (group 2) or NR 7 4, which may be H, Na, K, Li or NH4. Above Rf n0 may be one in which 50% or more of H is substituted with fluorine.

[0109] The above general formula (N 0 ) is represented by the following: The following general formula (N 1 ): X n0 -(CF2) m1 -Y 0 (N 1 ) (In the formula, X n0 is H, Cl, or F; m1 is an integer of 3 to 15; Y 0 is as defined above, a compound represented by the following general formula (N 2 ): Rf n1 -O-(CF(CF3)CF2O) m2 CFX n1 -Y 0 (N 2 ) (In the formula, Rf n1 is a perfluoroalkyl group having 1 to 5 carbon atoms, m2 is an integer of 0 to 3, and X n1 is F or CF3, and Y 0 is defined above.) a compound represented by the following general formula (N 3 ): Rf n2 (CH2) m3 -(Rfn3 ) q -Y 0 (N 3 ) (In the formula, Rf n2 is a partially or fully fluorinated alkyl group having 1 to 13 carbon atoms which may contain an ether bond, m3 is an integer of 1 to 3, Rf n3 is a linear or branched perfluoroalkylene group having 1 to 3 carbon atoms, q is 0 or 1, and Y 0 is defined above.) a compound represented by the following general formula (N 4 ): Rf n4 -O-(CY n1 Y n2 ) p CF2-Y 0 (N 4 ) (In the formula, Rf n4 is a linear or branched partially or fully fluorinated alkyl group having 1 to 12 carbon atoms, which may contain an ether bond and / or a chlorine atom; Y n1 and Y n2 are the same or different and are H or F, p is 0 or 1, and Y 0 is as defined above.) and a compound represented by the general formula (N 5 ): [ka] (In the formula, X n2 , X n3 and X n4 Rf may be the same or different and are H, F, or a linear or branched partially or completely fluorinated alkyl group having 1 to 6 carbon atoms, which may contain an ether bond. n5 is a linear or branched, partially or completely fluorinated alkylene group having 1 to 3 carbon atoms, which may contain an ether bond; L is a linking group; Y 0 is as defined above, where X n2 , X n3 , X n4 and Rf n5 The total number of carbon atoms is 18 or less.

[0110] The above general formula (N 0 More specifically, the compound represented by the formula (I) is a perfluorocarboxylic acid (I), a ω-H perfluorocarboxylic acid (II), a perfluoroether carboxylic acid (III), a perfluoroalkyl alkylene carboxylic acid (IV), a perfluoroalkoxy fluorocarboxylic acid (V), a perfluoroalkyl sulfonic acid (VI), a ω-H perfluoro sulfonic acid (VII), a perfluoroalkyl alkylene sulfonic acid (VIII), a perfluoroalkyl alkylene sulfonic acid (IX), a fluorocarboxylic acid (X), a fluorocarboxylic acid (X), a alkoxy fluoro sulfonic acid (XI), a compound (XII), a compound (XIII), and the like.

[0111] The perfluorocarboxylic acid (I) is represented by the following general formula (I): F(CF2) n1 COOM (I) (In the formula, n1 is an integer of 3 to 14, and M is H, a metal atom, or NR 7 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 7 is H or an organic group.

[0112] The ω-H perfluorocarboxylic acid (II) is represented by the following general formula (II): H(CF2) n2 COOM (II) (wherein n2 is an integer of 4 to 15, and M is as defined above).

[0113] The perfluoroether carboxylic acid (III) is represented by the following general formula (III): Rf 1 -O-(CF(CF3)CF2O) n3 CF(CF3)COOM (III) (In the formula, Rf 1 is a perfluoroalkyl group having 1 to 5 carbon atoms, n3 is an integer of 0 to 3, and M is as defined above.

[0114] The perfluoroalkyl alkylene carboxylic acid (IV) is represented by the following general formula (IV): Rf 2 (CH2) n4 Rf 3 COOM (IV) (In the formula, Rf 2 is a perfluoroalkyl group having 1 to 5 carbon atoms, and Rf 3 is a linear or branched perfluoroalkylene group having 1 to 3 carbon atoms, n4 is an integer of 1 to 3, and M is as defined above.

[0115] The alkoxyfluorocarboxylic acid (V) is represented by the following general formula (V): Rf 4 -O-CY 1 Y 2 CF2-COOM (V) (In the formula, Rf 4 is a linear or branched partially or fully fluorinated alkyl group having 1 to 12 carbon atoms, which may contain an ether bond and / or a chlorine atom; Y 1 and Y 2 are the same or different and are H or F, and M is as defined above.

[0116] The perfluoroalkylsulfonic acid (VI) is represented by the following general formula (VI): F(CF2) n5 SO3M (VI) (wherein n5 is an integer of 3 to 14, and M is as defined above).

[0117] The above ω-H perfluorosulfonic acid (VII) is represented by the following general formula (VII): H(CF2) n6 SO3M (VII) (wherein n6 is an integer of 4 to 14, and M is as defined above).

[0118] The perfluoroalkyl alkylene sulfonic acid (VIII) is represented by the following general formula (VIII): Rf 5 (CH2) n7 SO3M (VIII) (In the formula, Rf 5 is a perfluoroalkyl group having 1 to 13 carbon atoms, n7 is an integer of 1 to 3, and M is as defined above.

[0119] The alkyl alkylene carboxylic acid (IX) is represented by the following general formula (IX): Rf 6 (CH2) n8 COOM (IX) (In the formula, Rf 6 is a linear or branched partially or completely fluorinated alkyl group having 1 to 13 carbon atoms which may contain an ether bond, n8 is an integer from 1 to 3, and M is as defined above.

[0120] The fluorocarboxylic acid (X) is represented by the following general formula (X): Rf 7 -O-Rf 8 -O-CF2-COOM (X) (In the formula, Rf 7 is a linear or branched partially or fully fluorinated alkyl group having 1 to 6 carbon atoms, which may contain an ether bond and / or a chlorine atom; Rf 8 is a linear or branched, partially or fully fluorinated alkyl group having 1 to 6 carbon atoms, and M is as defined above.

[0121] The alkoxyfluorosulfonic acid (XI) is represented by the following general formula (XI): Rf 9 -O-CY 1 Y 2 CF2-SO3M (XI) (In the formula, Rf 9 is a linear or branched alkyl group having 1 to 12 carbon atoms, which may contain an ether bond, and which may contain chlorine, and which is partially or completely fluorinated; Y 1 and Y 2 are the same or different and are H or F, and M is as defined above.

[0122] The compound (XII) is represented by the following general formula (XII): [ka] (In the formula, X 1 , X 2 and X 3 Rf may be the same or different and are H, F and linear or branched partially or completely fluorinated alkyl groups having 1 to 6 carbon atoms, which may contain ether bonds; 10 is a perfluoroalkylene group having 1 to 3 carbon atoms, L is a linking group, and Y 0 is an anionic group. Y 0 may be -COOM, -SO2M, or -SO3M, or may be -SO3M or COOM, where M is as defined above. Examples of L include a single bond and a partially or completely fluorinated alkylene group having 1 to 10 carbon atoms which may contain an ether bond.

[0123] The compound (XIII) is represented by the following general formula (XIII): Rf 11 -O-(CF2CF(CF3)O) n9 (CF2O) n10 CF2COOM (XIII) (In the formula, Rf 11is a fluoroalkyl group containing chlorine and having 1 to 5 carbon atoms, n9 is an integer of 0 to 3, n10 is an integer of 0 to 3, and M is as defined above.) Compound (XIII) is represented by CF2ClO(CF2CF(CF3)O) n9 (CF2O) n10 CF2COONH4 (a mixture having an average molecular weight of 750, where n9 and n10 are defined above).

[0124] As described above, examples of the anionic fluorine-containing surfactant include carboxylic acid surfactants and sulfonic acid surfactants.

[0125] The fluorine-containing surfactant may be one type of fluorine-containing surfactant or a mixture containing two or more types of fluorine-containing surfactants.

[0126] The fluorine-containing surfactant may be a compound represented by the following formula: The fluorine-containing surfactant may be a mixture of these compounds. In one embodiment of the above polymerization, the monomer (I) is polymerized substantially in the absence of the compound represented by the following formula: F(CF2)7COOM, F(CF2)5COOM, H(CF2)6COOM, H(CF2)7COOM, CF3O(CF2)3OCHFCF2COOM, C3F7OCF(CF3)CF2OCF(CF3)COOM, CF3CF2CF2OCF(CF3)COOM, CF3CF2OCF2CF2OCF2COOM, C2F5OCF(CF3)CF2OCF(CF3)COOM, CF3OCF(CF3)CF2OCF(CF3)COOM, CF2ClCF2CF2OCF(CF3)CF2OCF2COOM, CF2ClCF2CF2OCF2CF(CF3)OCF2COOM, CF2ClCF(CF3)OCF(CF3)CF2OCF2COOM, CF2ClCF(CF3)OCF2CF(CF3)OCF2COOM, [ka] (In each formula, M is H, metal atom, NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group.

[0127] In the manufacturing method of the present disclosure, the polymerization of the monomer (I) is carried out in an aqueous medium, so that an aqueous solution containing a fluoropolymer and an aqueous medium is usually obtained. The aqueous solution containing the obtained fluoropolymer may be used for various applications as it is, or the fluoropolymer obtained by separating it from the aqueous solution may be used for various applications. The method of separating the fluoropolymer from the aqueous solution is not particularly limited. For example, the fluoropolymer can be separated by methods such as coagulation, washing, and drying of the fluoropolymer in the aqueous solution.

[0128] The fluoropolymer or aqueous solution obtained by polymerization of the monomer (I) contains a fraction having a molecular weight of 3000 or less, a dimer and a trimer of the monomer (I), etc. In order to remove these, the fluoropolymer or aqueous solution obtained by polymerization of the monomer (I) may be subjected to post-treatment.

[0129] For example, in the manufacturing method of the present disclosure, after the polymerization of the monomer (I) is completed, a composition containing an aqueous medium and a fluoropolymer is recovered, and the obtained composition may be treated by at least one means selected from the group consisting of ultrafiltration, microfiltration, dialysis membrane treatment, liquid separation and reprecipitation.

[0130] The composition obtained by carrying out polymerization of monomer (I) generally contains more than 1.0 mass% of dimers and trimers in total as the fluoropolymer of monomer (I) relative to the mass of the fluoropolymer of monomer (I). The content of dimers and trimers in the fluoropolymer of monomer (I) may be, for example, 2.0 mass% or more, 3.0 mass% or more, 30.0 mass% or less, or 20.0 mass% or less relative to the fluoropolymer of monomer (I). The content of dimers and trimers in the composition can be determined by performing gel permeation chromatography (GPC) analysis of the composition and calculating the ratio (area percentage) of the total peak area of ​​dimers and trimers to the total area of ​​each peak of the chromatogram obtained by GPC analysis.

[0131] Next, the composition containing the obtained aqueous medium and the fluoropolymer is recovered, and the obtained composition is preferably treated by at least one means selected from the group consisting of ultrafiltration, microfiltration, dialysis membrane treatment, liquid separation, and reprecipitation. By this treatment, the dimer and trimer of the monomer (I) contained in the composition obtained by polymerization of the monomer (I) can be removed from the composition. As the treatment means, at least one means selected from the group consisting of ultrafiltration, microfiltration, liquid separation, and reprecipitation is more preferable, at least one means selected from the group consisting of ultrafiltration and liquid separation is even more preferable, and ultrafiltration is particularly preferable.

[0132] The polymerization of monomer (I) produces dimers and trimers of monomer (I), and as a result, the dimers and trimers of monomer (I) are contained in the fluoropolymer. The mechanism by which dimers and trimers of monomer (I) are produced is not entirely clear, but it is speculated that dimerization and trimerization of monomer (I) occurs with a non-negligible frequency due to the polymerization reaction in a polymerization system in which monomer (I) accounts for the majority of the monomers present in the polymerization system.

[0133] When removing the dimer and trimer, the unreacted monomer (I) is usually removed from the composition at the same time. Also, by appropriately selecting the post-treatment means, it is possible to remove the fraction having a molecular weight of 3000 or less.

[0134] The composition obtained by polymerization of the monomer (I) may be a composition obtained by polymerization as-polymerized, or may be a composition obtained by diluting or concentrating the composition obtained by polymerization as-polymerized, or may be a composition that has been subjected to a dispersion stabilization treatment, etc. In order to smoothly proceed with ultrafiltration, microfiltration, or dialysis membrane treatment, it is also preferable to adjust the viscosity of the composition by these treatments.

[0135] The content of the fluoropolymer of the monomer (I) in the composition is not particularly limited, and may be, for example, 0.1 to 20% by mass. From the viewpoint of the efficiency of removing dimers and trimers, the content of the fluoropolymer in the composition is preferably 18.0% by mass or less, more preferably 15.0% by mass or less, even more preferably 12.0% by mass or less, particularly preferably 10.0% by mass or less, preferably 0.5% by mass or more, more preferably 1.0% by mass or more, even more preferably 1.2% by mass or more, and particularly preferably 1.5% by mass or more. The content of the fluoropolymer in the composition can be adjusted, for example, by a method of adding water to the composition obtained by polymerization of the monomer (I), a method of concentrating the composition obtained by polymerization of the monomer (I), or the like.

[0136] The pH of the composition is preferably 0 to 11, more preferably 0.5 to 8.0, and further preferably 1.0 to 7.0. The pH of the composition can be adjusted by adding a pH adjuster to the composition obtained by polymerization of the monomer (I). The pH adjuster may be an acid or an alkali, and examples of the pH adjuster include phosphates, sodium hydroxide, potassium hydroxide, and aqueous ammonia.

[0137] The viscosity of the composition is preferably 25 mPa s or less, since this allows the ultrafiltration, microfiltration or dialysis membrane treatment to proceed smoothly. The viscosity of the composition can be adjusted, for example, by adjusting the weight average molecular weight and number average molecular weight of the fluoropolymer, by adjusting the concentration of the fluoropolymer in the composition, by adjusting the temperature of the composition, or the like.

[0138] The above-mentioned ultrafiltration or microfiltration may be performed by either a cross-flow system or a dead-end system without any particular limitation, but the cross-flow system is preferred from the viewpoint of reducing clogging of the membrane.

[0139] The ultrafiltration can be carried out using an ultrafiltration membrane. For example, the ultrafiltration can be carried out using an ultrafiltration device having an ultrafiltration membrane, and centrifugal ultrafiltration, batch ultrafiltration, circulation ultrafiltration, etc. can be adopted.

[0140] The molecular weight cutoff of the ultrafiltration membrane is usually 0.1×10 4 ~30×10 4 The molecular weight cutoff of the ultrafiltration membrane is about 1.5 × 10 Da because it can suppress clogging of the membrane and efficiently reduce dimers and trimers. 4 The molecular weight cutoff is preferably 2.0×10 Da or more. 4 Da or more is more preferable, 3.0×10 4 Da or more is particularly preferable, and 5.0×10 4 Da or more is most preferable. The molecular weight cutoff is 8.0×10 4 From the viewpoint of the efficiency of removing dimers and trimers, the molecular weight cutoff may be 20×10 Da or more. 4 Da or less is preferable, 10×10 4 Da or less is more preferable.

[0141] The molecular weight cutoff of the ultrafiltration membrane can be determined by, for example, passing polystyrene with a known weight average molecular weight through the membrane and determining the molecular weight at which 90% of the polystyrene is rejected. Quantitative determination of polystyrene can be performed using gel permeation chromatography.

[0142] The shape of the ultrafiltration membrane may be any of the conventionally known shapes, but is not limited thereto. For example, hollow fiber type, flat membrane type, spiral type, tubular type, etc. From the viewpoint of preventing clogging, the hollow fiber type is preferred. The inner diameter of the hollow fiber ultrafiltration membrane is not limited, but may be, for example, 0.1 to 2 mm, and is preferably 0.8 to 1.4 mm. The length of the hollow fiber ultrafiltration membrane is not limited, but may be, for example, 0.05 to 3 m, and is preferably 0.05 to 2 m.

[0143] The material of the ultrafiltration membrane is not particularly limited, but examples thereof include organic materials such as cellulose, cellulose ester, polysulfone, sulfonated polysulfone, polyethersulfone, sulfonated polyethersulfone, chlorinated polyethylene, polypropylene, polyolefin, polyvinyl alcohol, polymethyl methacrylate, polyacrylonitrile, polyvinylidene fluoride, and polytetrafluoroethylene; metals such as stainless steel; and inorganic materials such as ceramics. The material of the ultrafiltration membrane is preferably an organic material, more preferably chlorinated polyethylene, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, polyacrylonitrile, polysulfone, or polyethersulfone, and even more preferably polyacrylonitrile or polyvinylidene fluoride.

[0144] Specific examples of the ultrafiltration membrane include G-5 type, G-10 type, G-20 type, G-50 type, PW type, and HWS UF type manufactured by DESAL; HFM-180, HFM-183, HFM-251, HFM-300, HFM-116, HFM-183, HFM-300, HFK-131, HFK-328, MPT-U20, MPS-U20P, and MPS-U20S manufactured by KOCH; SPE1, SPE3, SPE5, SPE10, SPE30, SPV5, SPV50, and SOW30 manufactured by Synder; Microza (registered trademark) UF series manufactured by Asahi Kasei Corporation; and NTR7410 manufactured by Nitto Denko Corporation.

[0145] From the viewpoint of the efficiency of removing dimers and trimers, the ultrafiltration is preferably carried out at a pressure of 0.01 MPa or more, more preferably 0.03 MPa or more, and even more preferably 0.05 MPa or more. From the viewpoint of pressure resistance, the pressure is preferably 0.5 MPa or less, more preferably 0.25 MPa or less, and even more preferably 0.2 MPa or less.

[0146] From the viewpoint of the efficiency of removing dimers and trimers, the ultrafiltration is preferably carried out at a flow rate of 10 mL / min or more, more preferably at a flow rate of 50 mL / min or more, and is preferably carried out at a flow rate of 5000 mL / min or less, more preferably at a flow rate of 1000 mL / min or less.

[0147] The above-mentioned microfiltration can be carried out using a microfiltration membrane. The microfiltration membrane usually has an average pore size of 0.05 to 1.0 μm. The microfiltration membrane preferably has an average pore size of 0.1 μm or more, more preferably 0.075 μm or more, and even more preferably 0.1 μm or more, in order to efficiently remove dimers and trimers. The average pore size is preferably 1.00 μm or less, more preferably 0.50 μm or less, and even more preferably 0.25 μm or less. The average pore size of the microfiltration membrane can be measured in accordance with ASTM F 316-03 (bubble point method).

[0148] The shape of the microfiltration membrane is not limited to any particular one and may be any of the conventionally known shapes, such as hollow fiber type, flat membrane type, spiral type, tubular type, etc. From the viewpoint of preventing clogging, the hollow fiber type is preferred. The inner diameter of the hollow fiber microfiltration membrane is not limited, but may be, for example, 0.1 to 2 mm, and is preferably 0.8 to 1.4 mm. The length of the hollow fiber microfiltration membrane is not limited, but may be, for example, 0.05 to 3 m, and is preferably 0.05 to 2 m.

[0149] Examples of materials for the microfiltration membrane include cellulose-based, aromatic polyamide, polyvinyl alcohol, polysulfone, polyethersulfone, polyvinylidene fluoride, polyethylene, polyacrylonitrile, polypropylene, polycarbonate, polytetrafluoroethylene, ceramics, metals, etc. Among these, aromatic polyamide, polyvinyl alcohol, polysulfone, polyvinylidene fluoride, polyethylene, polyacrylonitrile, polypropylene, polycarbonate, or polytetrafluoroethylene is preferred, and polyacrylonitrile or polyvinylidene fluoride is particularly preferred.

[0150] Specific examples of microfiltration membranes include Cefilt manufactured by NGK Insulators, Ltd.; Microza U series and Microza P series manufactured by Asahi Kasei Corporation; Poreflon SPMW, Poreflon OPMW, and Poreflon PM manufactured by Sumitomo Electric Industries, Ltd.; Torayfil manufactured by Toray Industries, Inc.; NADIR MP005 and NADIR MV020 manufactured by Microdyne Nadia, Inc.; and X-flow manufactured by Norit.

[0151] From the viewpoint of the efficiency of removing dimers and trimers, the microfiltration is preferably carried out at a pressure of 0.01 MPa or more, more preferably 0.03 MPa or more, and even more preferably 0.05 MPa or more. From the viewpoint of pressure resistance, the pressure is preferably 0.5 MPa or less, more preferably 0.25 MPa or less, and even more preferably 0.2 MPa or less.

[0152] From the viewpoint of the efficiency of removing dimers and trimers, the above-mentioned microfiltration is preferably carried out at a flow rate of 10 mL / min or more, more preferably at a flow rate of 50 mL / min or more, and is preferably carried out at a flow rate of 5000 mL / min or less, more preferably at a flow rate of 1000 mL / min or less.

[0153] The dialysis membrane treatment is carried out using a dialysis membrane. 4 ~100×10 4 It has a molecular weight cutoff of Da. The above dialysis membrane suppresses clogging of the membrane and can efficiently remove dimers and trimers, so the molecular weight cutoff is 0.3 × 10 4 The molecular weight cutoff is preferably 0.5×10 Da or more. 4 Da or more is preferable, 1.0×10 4 Da or more is more preferable, and 1.5×10 4 Da or more is even more preferable, and 2.0×10 4 Da or more is particularly preferred, and 3.0×10 4 Da or more is particularly preferable, and 5.0×10 4 Da or more is most preferable. The above molecular weight cutoff is 8.0 × 10 4 It may be more than Da. From the viewpoint of the efficiency of removing dimers and trimers, the above molecular weight cutoff is set to 20×10 4 Da or less is preferable, 10×10 4 Da or less is more preferable. The molecular weight cutoff of the dialysis membrane can be measured, for example, in the same manner as that for the ultrafiltration membrane.

[0154] The material of the dialysis membrane is not particularly limited, but examples thereof include cellulose, polyacrylonitrile, polymethyl methacrylate, ethylene-vinyl alcohol copolymer, polysulfone, polyamide, and polyester-based polymer alloy.

[0155] Specific examples of dialysis membranes include Spectra / Por (registered trademark) Float-A-Lyzer, Tube-A-Lyzer, Dialysis tubing, 6Dialysis tubing, and 7Dialysis tubing manufactured by Spectrum Laboratories.

[0156] The ultrafiltration, microfiltration or dialysis membrane treatment is preferably carried out at a temperature of 10° C. or higher. More preferably, it is 15° C. or higher, even more preferably, it is 20° C. or higher, and particularly preferably, it is 30° C. or higher. By setting the temperature within the above range, dimers and trimers can be reduced more efficiently. The temperature is preferably 90° C. or lower, more preferably 80° C. or lower, even more preferably 70° C. or lower, and particularly preferably 60° C. or lower.

[0157] The ultrafiltration, microfiltration or dialysis membrane treatment can be carried out while adding water to the composition or while adjusting the pH of the composition. Water may be added to the composition intermittently or continuously.

[0158] The end point of the ultrafiltration, microfiltration or dialysis membrane treatment may be appropriately determined and is not limited. In addition, the ultrafiltration, microfiltration or dialysis membrane treatment may be backwashed with water about once every 1 to 24 hours of filtration time to improve the durability of the filtration membrane.

[0159] The separation can be carried out, for example, by adding an organic solvent to the composition, separating it into two phases, an aqueous phase and an organic solvent phase, and recovering the aqueous phase.

[0160] The reprecipitation can be carried out, for example, by dropping the composition into a poor solvent to precipitate the fluoropolymer, recovering the precipitated fluoropolymer, dissolving the recovered fluoropolymer in a good solvent, dropping the resulting solution into a poor solvent to precipitate the fluoropolymer again, and recovering the precipitated fluoropolymer.

[0161] By post-treating the composition containing the fluoropolymer of the monomer (I) by the above-mentioned means, an aqueous solution containing a fluoropolymer that is substantially free of dimers and trimers, or an aqueous solution containing a fluoropolymer with a reduced content of fractions with molecular weights of 3000 or less can usually be obtained. The aqueous solution containing the fluoropolymer obtained by treating the composition may be used for various applications as it is, or the fluoropolymer obtained by separating it from the aqueous solution may be used for various applications. The method for separating the fluoropolymer from the aqueous solution is not particularly limited. For example, the fluoropolymer can be separated by methods such as coagulation, washing, and drying of the fluoropolymer in the aqueous solution.

[0162] The manufacturing method of the present disclosure provides a fluoropolymer or an aqueous solution containing a fluoropolymer and an aqueous medium. The present disclosure also relates to a fluoropolymer. In particular, the content of polymerized units (I) is 50 mol% or more relative to the total polymerized units constituting the fluoropolymer, and the weight average molecular weight (Mw) is 38.0×10 4 The above-mentioned fluoropolymer has a high molecular weight despite containing a large amount of polymerization unit (I), and therefore can be suitably used as a fluoropolymer that can easily form a uniform coating film having a desired thickness.

[0163] The fluoropolymer may be a homopolymer consisting of only the polymerized units (I) based on the monomer (I), or may be a copolymer containing the polymerized units (I) and polymerized units based on other monomers copolymerizable with the monomer (I). The other monomers are as described above. The polymerized units (I) may be the same or different in each occurrence, and the fluoropolymer may contain polymerized units (I) based on two or more different monomers represented by the general formula (I).

[0164] The content of the polymerization unit (I) in the fluoropolymer is, in order of preference, 1.0 mol% or more, 3.0 mol% or more, 5.0 mol% or more, 10 mol% or more, 20 mol% or more, 30 mol% or more, 40 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, and 99 mol% or more, based on the total polymerization units constituting the fluoropolymer. The content of the polymerization unit (I) is particularly preferably substantially 100 mol%, and the fluoropolymer is most preferably composed only of the polymerization unit (I). The higher the content of the polymerization unit (I) in the fluoropolymer, the more advantageously the water solubility of the fluoropolymer increases.

[0165] In the fluoropolymer, the content of the polymerization units based on other monomers copolymerizable with the monomer (I) is, in order of preference, 99.0 mol% or less, 97.0 mol% or less, 95.0 mol% or less, 90 mol% or less, 80 mol% or less, 70 mol% or less, 60 mol% or less, 50 mol% or less, 40 mol% or less, 30 mol% or less, 20 mol% or less, 10 mol% or less, and 1 mol% or less, based on the total polymerization units constituting the fluoropolymer. It is particularly preferable that the content of the polymerization units based on other monomers copolymerizable with the monomer (I) is substantially 0 mol%, and it is most preferable that the fluoropolymer does not contain any polymerization units based on other monomers.

[0166] According to the manufacturing method of the present disclosure, a fluoropolymer having a very high molecular weight can be manufactured. In the conventional technology, when a large amount of polymerized units (I) is introduced into a fluoropolymer, a fluoropolymer having a high molecular weight cannot be manufactured. According to the manufacturing method of the present disclosure, even when a large amount of polymerized units (I) is introduced into a fluoropolymer so that the content of the polymerized units (I) is 50 mol % or more relative to the total polymerized units constituting the fluoropolymer, a high molecular weight fluoropolymer can be manufactured.

[0167] The lower limit of the weight average molecular weight of the fluoropolymer is preferably 0.2×10 4 Above, 0.4×10 4Above, 0.6×10 4 Above, 0.8 x 10 4 That's it, 1.0 x 10 4 That's it, 2.0 x 10 4 That's it, 5.0 x 10 4 That's it, 10.0 x 10 4 That's it, 15.0 x 10 4 That's it, 20.0 x 10 4 That's it, 25.0 x 10 4 That's it, 30.0 x 10 4 , 35.0×10 4 , 38.0×10 4 , 40.0×10 4 The upper limit of the weight average molecular weight of the fluoropolymer is, in order of preference, 150.0×10 4 Below, 100.0 x 10 4 Below, 60.0 x 10 4 The following is as follows.

[0168] The lower limit of the number average molecular weight of the fluoropolymer is preferably 0.1×10 4 Above, 0.2×10 4 Above, 0.3×10 4 Above, 0.4×10 4 Above, 0.5 x 10 4 That's it, 1.0 x 10 4 That's it, 3.0 x 10 4 That's it, 3.1 x 10 4 That's it, 5.0 x 10 4 , 8.0×10 4 That's it, 10.0 x 10 4 That's it, 12.0 x 10 4 The upper limit of the number average molecular weight of the fluoropolymer is, in order of preference, 75.0×10 4 Below, 50.0 x 10 4 Below, 40.0 x 10 4 Below, 30.0 x 10 4 The following is the result.

[0169] The number average molecular weight and weight average molecular weight are values ​​calculated by gel permeation chromatography (GPC) using monodisperse polyethylene oxide (PEO) and polyethylene glycol (PEG) as standards. If measurement by GPC is not possible, the number average molecular weight of the fluoropolymer can be determined from the correlation between the number average molecular weight calculated from the number of terminal groups obtained by NMR, FT-IR, etc. and the melt flow rate. The melt flow rate can be measured in accordance with JIS K 7210.

[0170] Fluoropolymers usually have end groups. The end groups are end groups generated during polymerization, and representative end groups are independently selected from hydrogen, iodine, bromine, linear or branched alkyl groups, and linear or branched fluoroalkyl groups, and may optionally contain at least one catenary heteroatom. The alkyl or fluoroalkyl groups preferably have 1 to 20 carbon atoms. These end groups are generally generated from the initiator or chain transfer agent used to form the fluoropolymer, or are generated during the chain transfer reaction.

[0171] The fluoropolymers preferably have an ion exchange ratio (IXR) of 53 or less, where IXR is defined as the number of carbon atoms in the polymer backbone relative to the ionizable group. Precursor groups that become ionic upon hydrolysis (e.g., -SO2F) are not considered ionic groups for purposes of determining IXR.

[0172] IXR is preferably 0.5 or more, more preferably 1 or more, even more preferably 3 or more, even more preferably 4 or more, particularly preferably 5 or more, and particularly preferably 8 or more. IXR is more preferably 43 or less, more preferably 33 or less, and particularly preferably 23 or less.

[0173] The ion exchange capacity of the fluoropolymer is, in order of preference, 0.80 meq / g or more, 1.50 meq / g or more, 1.75 meq / g or more, 2.00 meq / g or more, 2.20 meq / g or more, more than 2.20 meq / g, 2.50 meq / g or more, 2.60 meq / g or more, 3.00 meq / g or more, and 3.50 meq / g or more. The ion exchange capacity is the content of ionic groups (anionic groups) in the fluoropolymer, and is calculated from the composition of the fluoropolymer.

[0174] In fluoropolymers, the ionic (anionic) groups are typically distributed along the polymer backbone. Fluoropolymers comprise a polymer backbone with recurring side chains attached to the backbone, which preferably carry ionic groups.

[0175] The fluoropolymer preferably comprises ionizable groups having a pKa of less than 10, more preferably less than 7. The ionizable groups of the fluoropolymer are preferably selected from the group consisting of sulfonates, carboxylates, phosphonates, and phosphates.

[0176] The terms "sulfonate, carboxylate, phosphonate, and phosphate" are intended to refer to the respective salts or to the respective acids capable of forming salts. When salts are used, preferably the salts are alkali metal or ammonium salts. A preferred ionic group is the sulfonate group.

[0177] The fluoropolymer is preferably water-soluble. Water-soluble means the property of being easily dissolved or dispersed in an aqueous medium. The particle size of a water-soluble fluoropolymer cannot be measured by, for example, dynamic light scattering (DLS). On the other hand, the particle size of a water-insoluble fluoropolymer can be measured by, for example, dynamic light scattering (DLS).

[0178] The aqueous solution containing the fluoropolymer and the aqueous medium can also be used for various purposes. The content of the fluoropolymer in the aqueous solution is preferably 0.1% by mass or more, more preferably 1.0% by mass or more, even more preferably 1.5% by mass or more, particularly preferably 2.0% by mass or more, and preferably 20% by mass or less, more preferably 15% by mass or less, based on the aqueous solution.

[0179] The fluoropolymer or the aqueous solution containing the fluoropolymer may be substantially free of dimers and trimers of the monomer (I). The dimers and trimers of the monomer (I) are usually generated when the monomer (I) is polymerized to obtain a fluoropolymer. The content of the dimers and trimers in the fluoropolymer is 1.0% by mass or less, preferably 0.1% by mass or less, more preferably 0.01% by mass or less, even more preferably 0.001% by mass or less, and particularly preferably 0.0001% by mass or less, based on the fluoropolymer.

[0180] The contents of dimers and trimers in a fluoropolymer can be determined by subjecting the fluoropolymer to gel permeation chromatography (GPC) analysis and calculating the ratio (area percentage) of the total peak area of ​​the dimer and trimer to the total area of ​​each peak in the chromatogram obtained by GPC analysis.

[0181] When the content of dimers and trimers in a fluoropolymer is less than 0.5% by mass relative to the fluoropolymer, it can be identified by measurement using liquid chromatography-mass spectrometry (LC / MS). Specifically, aqueous solutions with five or more levels of monomer (I) content are prepared, LC / MS analysis is performed for each content, and the relationship between the content and the area (peak integral value) for that content is plotted to create a calibration curve for monomer (I). Furthermore, from the calibration curve for monomer (I), calibration curves for the dimer and trimer of monomer (I) are created. Methanol is added to the fluoropolymer to prepare a mixture, and an extract (supernatant) is recovered from the mixture by centrifugation, and the obtained extract is subjected to LC / MS analysis. Then, using the calibration curve, the area (peak integral value) of the chromatogram of the dimer and trimer of the monomer (I) can be converted into the content of the dimer and trimer.

[0182] The content of the fraction having a molecular weight of 3000 or less in the fluoropolymer or an aqueous solution containing the fluoropolymer may be 3.7% or less, preferably 3.2% or less, more preferably 2.7% or less, even more preferably 1.7% or less, especially preferably 1.2% or less, particularly preferably 1.0% or less, and most preferably 0.6% or less, based on the fluoropolymer. The lower limit of the content of the fraction having a molecular weight of 3000 or less is not limited, but is, for example, 0.01%.

[0183] The content of the fraction having a molecular weight of 3000 or less can be calculated from the peak area of ​​GPC. The fraction having a molecular weight of 3000 or less includes all compounds having a molecular weight of 3000 or less.

[0184] The fluoropolymer or the aqueous solution containing the fluoropolymer is preferably substantially free of fluorine-containing surfactant. In the present disclosure, "substantially free of fluorine-containing surfactant" means that the content of the fluorine-containing surfactant in the fluoropolymer or the aqueous solution is 10 mass ppm or less, preferably 1 mass ppm or less, more preferably 100 mass ppb or less, even more preferably 10 mass ppb or less, still more preferably 1 mass ppb or less, and particularly preferably the fluorine-containing surfactant is below the detection limit as measured by liquid chromatography-mass spectrometry (LC / MS).

[0185] The content of the fluorine-containing surfactant can be quantified by a known method, for example, by LC / MS analysis. First, methanol is added to the fluoropolymer or aqueous solution to perform extraction, and the resulting extract is analyzed by LC / MS. To further increase the extraction efficiency, Soxhlet extraction, ultrasonic treatment, etc. may be performed. Molecular weight information is extracted from the obtained LC / MS spectrum, and a match with the structural formula of the candidate fluorine-containing surfactant is confirmed. Then, aqueous solutions containing five or more levels of the confirmed fluorine-containing surfactant are prepared, and LC / MS analysis is performed on the aqueous solutions containing each level. The relationship between the content and the area for each content is plotted, and a calibration curve is drawn. Then, using the calibration curve, the area of ​​the LC / MS chromatogram of the fluorine-containing surfactant in the extract can be converted into the content of the fluorine-containing surfactant.

[0186] Fluoropolymers or aqueous solutions containing fluoropolymers can be used in a variety of applications, for example, as components of coating compositions, since the fluoropolymers have high molecular weights.

[0187] The coating composition is preferably a composition comprising a fluoropolymer and at least one solvent selected from the group consisting of water and alcohol. By using such a coating composition, a coating film exhibiting excellent anti-reflection effect can be formed. For example, the fluoropolymer contained in the coating composition has a weight average molecular weight (Mw) of 38.0×10 4 In the case of a fluoropolymer having a sufficiently high molecular weight, such as a fluoropolymer having a molecular weight of 100 to 1500 nm or more, a uniform coating film having a desired thickness can be easily formed, and the anti-reflection effect and hydrophilicity of the resulting coating film can be enhanced, and a sufficient dissolution rate in the developer can be obtained. In addition, the higher the content of the polymerized unit (I) in the fluoropolymer, the lower the refractive index and the better the solubility in the developer can be given to the coating film, which is preferable.

[0188] The solvent contained in the coating composition is at least one selected from the group consisting of water and alcohol. The alcohol is preferably a lower alcohol having 1 to 6 carbon atoms, more preferably at least one selected from the group consisting of methanol, ethanol, isopropanol, n-propanol, and butyl alcohol.

[0189] The coating composition may further contain a water-soluble organic solvent (excluding alcohol), at least one basic substance selected from ammonia or organic amines, a surfactant, an acid, a water-soluble polymer, a photoacid generator, an antifoaming agent, a light absorbing agent, a storage stabilizer, a preservative, an adhesive aid, a dye, etc.

[0190] The content of the fluoropolymer in the coating composition is preferably 0.1 to 50 mass %, more preferably 0.5 to 30 mass %, further preferably 1 to 20 mass %, particularly preferably 2 to 10 mass %, based on the coating composition.

[0191] A coating film can be prepared by applying the coating composition to a substrate. The method for applying the coating composition is not particularly limited, but includes roll coating, casting, dipping, spin coating, water casting, die coating, Langmuir-Blodgett method, etc.

[0192] The substrate to which the coating composition is applied includes a silicon wafer, quartz glass, and the like.

[0193] In particular, when strict control of the film thickness is required, application by the spin coating method is suitable. When using the spin coating method, the film thickness of the coating film is determined by the rotation speed of the substrate, the rotation time, the viscosity of the coating composition, etc. Due to the characteristics of the device (spin coater), if the rotation speed is too slow or the rotation time is too short, unevenness in the film thickness is likely to occur, so it is common to apply the film at a high rotation speed over a certain amount of time. However, when the coating composition is applied at a high rotation speed for a certain period of time, the resulting film thickness is small. Therefore, it is not easy to produce a relatively thick film while suppressing unevenness in film thickness by using the spin coating method. Even when the content of the polymerized unit (I) in the fluoropolymer is high, the coating composition of the present disclosure can impart excellent effects such as hydrophilicity to the coating film, and can easily produce a relatively thick film while suppressing unevenness in film thickness, since the fluoropolymer has a high molecular weight.

[0194] The coating film obtained from the coating composition is suitable as, for example, a pellicle or an antireflective film. For example, a photoresist laminate including a photoresist layer and an antireflective film can be produced by applying the coating composition onto a photoresist layer.

[0195] Although the embodiments have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the claims. EXAMPLES

[0196] Next, embodiments of the present disclosure will be described with reference to examples, but the present disclosure is not limited to these examples.

[0197] The values ​​in the examples were measured by the following methods.

[0198] (Oxygen concentration in reactor) The gas coming out of the exhaust gas line while nitrogen was being bubbled through the liquid in the reactor was measured and analyzed using a low-concentration oxygen analyzer (product name "PS-820-L", manufactured by Iijima Electronics Co., Ltd.) to determine the oxygen concentration during the reaction.

[0199] (Fluoropolymer concentration in aqueous solution (solids concentration)) Approximately 1 g of the aqueous solution containing the fluoropolymer was dried in a vacuum dryer at 60°C for 60 minutes, and the mass of the heating residue was measured. The ratio of the mass of the heating residue to the mass of the aqueous solution (1 g) was expressed as a percentage and used as the value.

[0200] (Method of measuring weight average molecular weight (Mw) and number average molecular weight (Mn)) The Mw and Mn of the fluoropolymers were determined by gel permeation chromatography (GPC) using an Agilent Technologies 1260 Infinity II column (TSKgel G3000PW) and a Tosoh column (TSKgel G3000PW). XL 1 bottle of TSKgel GMPW XL The molecular weight was determined by using a column containing one column (connected in series) and a mixed solvent of Tris buffer and acetonitrile (Tris buffer:acetonitrile = 8:2 (v / v)) at a flow rate of 0.5 ml / min. Monodisperse polyethylene oxide (PEO) and polyethylene glycol (PEG) were used as standards to calculate the molecular weight.

[0201] (Method for measuring the content of dimers and trimers of monomers in fluoropolymers) (1) Extraction from aqueous solution The solid content of the aqueous solution of the fluoropolymer was measured, and an amount of the aqueous solution equivalent to 0.2 g of the solid content of the fluoropolymer was weighed. Then, the aqueous solution was combined with the water contained in the aqueous solution, and water and methanol were added so that the volume ratio of water to methanol was 50 / 50 (volume %) to obtain a mixture containing the fluoropolymer, water, and methanol. Then, the obtained mixture was centrifuged at 4000 rpm for 1 hour, and the supernatant containing the fluoropolymer was collected as an extract. The extract was analyzed using a liquid chromatograph mass spectrometer (Waters, LC-MS ACQUITY UPLC / TQD) to obtain a chromatogram of the extract. The contents of dimers and trimers of the monomer contained in the extract were determined by converting the integral values ​​of the peaks derived from the dimers and trimers of the monomer appearing in the chromatogram of the extract into the contents of dimers and trimers of the monomer using a calibration curve of the analogous monomer.

[0202] (2) Monomer calibration curve Five levels of methanol standard solutions of monomers with known contents ranging from 1 ng / mL to 100 ng / mL were prepared, and measurements were performed using a liquid chromatograph mass spectrometer (Waters, LC-MS ACQUITY UPLC / TQD). The relationship between the content of each monomer and the peak integral value for that content was plotted to create a calibration curve (first order approximation) for each monomer. Next, the calibration curves (first order approximation) for each monomer were used to create calibration curves for the dimers and trimers of each monomer.

[0203] Measurement equipment configuration and LC-MS measurement conditions [Table 1]

[0204] The limit of quantification for this measurement configuration is 1 ng / mL.

[0205] <Example 1> 7.5g of perfluoro-(6,6-dihydro-2-trifluoromethyl-3-oxa-5-hexenoic acid) and 17.5g of water were added to the reactor, and the liquid in the reactor was stirred at room temperature for 30 minutes while bubbling with N2. While stirring at 50°C, ammonium persulfate (APS) was added in an amount equivalent to 0.5 mol% relative to the amount of perfluoro-(6,6-dihydro-2-trifluoromethyl-3-oxa-5-hexenoic acid) to start the reaction. The reaction was terminated after 23 hours of stirring. The oxygen concentration in the reactor was in the range of 250 ppm by volume to 350 ppm by volume.

[0206] Water was added to the obtained aqueous solution containing the fluoropolymer to adjust the concentration of the fluoropolymer to 2.0% by mass, and then the solution was contacted with an ultrafiltration membrane (molecular weight cutoff 50000 Da, made of polyacrylonitrile) at 25°C and a water pressure of 0.1 MPa to perform ultrafiltration. Ultrafiltration was continued while appropriately injecting water until the filtrate was finally dissolved in an amount of water 7 times the amount of the aqueous solution, and an aqueous solution of the fluoropolymer was obtained. The concentration of the aqueous solution obtained by ultrafiltration was 2.1% by mass.

[0207] The aqueous solution obtained was analyzed by ultrafiltration. The weight average molecular weight (Mw) of the obtained fluoropolymer was 40.8×10 4 , number average molecular weight (Mn) is 10.2×10 4 The content of dimers and trimers in the aqueous solution obtained by ultrafiltration was 0.1% by mass or less based on the fluoropolymer.

[0208] <Example 2> Into the reactor, 1650g of perfluoro-(6,6-dihydro-2-trifluoromethyl-3-oxa-5-hexenoic acid) and 3850g of water were added, and the liquid in the reactor was stirred at room temperature for 30 minutes while bubbling with N2. While stirring at 52°C, ammonium persulfate (APS) was added in an amount equivalent to 0.5 mol% relative to the amount of perfluoro-(6,6-dihydro-2-trifluoromethyl-3-oxa-5-hexenoic acid) to start the reaction. The reaction was terminated after 23 hours of stirring. The oxygen concentration in the reactor was in the range of 11 ppm by volume to 20 ppm by volume.

[0209] The obtained aqueous solution containing the fluoropolymer was subjected to ultrafiltration in the same manner as in Example 1. The concentration of the aqueous solution obtained by carrying out the ultrafiltration was 2.1% by mass. The aqueous solution obtained was analyzed by ultrafiltration. The weight average molecular weight (Mw) of the obtained fluoropolymer was 46.0×10 4 , number average molecular weight (Mn) is 12.2 × 10 4The content of dimers and trimers in the aqueous solution obtained by ultrafiltration was 0.1% by mass or less based on the fluoropolymer.

[0210] <Comparative Example 1> A fluoropolymer was obtained in the same manner as in Example 1, except that the amount of perfluoro-(6,6-dihydro-2-trifluoromethyl-3-oxa-5-hexenoic acid) was changed to 17.5 g, the amount of water to 32.5 g, and the temperature was changed to 56°C, and the oxygen concentration in the reactor was changed to a maximum of 9400 ppm by volume.

[0211] The obtained aqueous solution containing the fluoropolymer was subjected to ultrafiltration in the same manner as in Example 1. The concentration of the aqueous solution obtained by carrying out the ultrafiltration was 2.0 mass %. The aqueous solution obtained was analyzed by ultrafiltration. The weight average molecular weight (Mw) of the obtained fluoropolymer was 19.6×10 4 , number average molecular weight (Mn) is 6.2×10 4 The content of dimers and trimers in the aqueous solution obtained by ultrafiltration was 0.1% by mass or less based on the fluoropolymer.

[0212] <Comparative Example 2> A fluoropolymer was obtained in the same manner as in Comparative Example 1, except that the temperature was changed to 80°C.

[0213] The obtained aqueous solution containing the fluoropolymer was subjected to ultrafiltration in the same manner as in Example 1. The concentration of the aqueous solution obtained by ultrafiltration was 2.0 mass%. The aqueous solution obtained by ultrafiltration was analyzed. The weight average molecular weight (Mw) of the obtained fluoropolymer was 9.6×10 4 , number average molecular weight (Mn) is 4.3×10 4 The content of dimers and trimers in the aqueous solution obtained by ultrafiltration was 0.1% by mass or less based on the fluoropolymer.

[0214] <Experimental Example 1 (Creation of Coating Film)> In order to form a 1 μm-thick membrane on a substrate, the aqueous solution obtained by ultrafiltration in Example 1 (the weight-average molecular weight (Mw) of the fluoropolymer was 40.8×10 4 The concentration of fluoropolymer was adjusted to prepare a polymer solution with a fluoropolymer concentration of 2 mass %. After stirring for 24 hours with a stirrer, the solution was filtered through a disposable syringe filter with a pore size of 0.2 μm to obtain a spin coating solution.

[0215] Using the obtained spin-coating solution and a commercially available programmable spin coater, spin-coating was performed on a silicon wafer substrate under the following conditions. The spin-coating solution was applied to the substrate while rotating the substrate at a rotation speed of 200 rpm for 10 seconds, and then the spin-coating solution was applied to the substrate while rotating the substrate at 2000 rpm for 50 seconds. Immediately after the film formation, the substrate was dried for 8 hours in a fan-type electric furnace at a temperature of 50°C, and the substrate on which the coating film was formed was taken out. The thickness of the coating film was measured at five points with a digital thickness gauge. The average thickness of the coating film was 1.03 μm, and a coating film having the desired thickness was formed uniformly.

[0216] <Comparative Experiment Example 1> The aqueous solution obtained by carrying out ultrafiltration in Comparative Example 1 (the weight average molecular weight (Mw) of the fluoropolymer was 19.6×10 4 A substrate having a coating film formed thereon was produced in the same manner as in Experimental Example 1, except that a coating film having an average thickness of 10.5 μm was obtained, and a film having the desired thickness was not obtained.

[0217] <Comparative Experiment Example 2> Except for changing the concentration of the fluoropolymer in the polymer solution to 10 mass %, a substrate having a coating film formed thereon was produced in the same manner as in Comparative Experimental Example 1. The average thickness of the obtained coating film was about 1 μm, but the thickness was uneven.

[0218] <Comparative Experiment Example 3> A substrate on which a coating film was formed was produced in the same manner as in Comparative Experimental Example 1, except that the rotation speed and rotation time were changed and the substrate was rotated at 200 rpm for 60 seconds while the spin coating solution was applied onto the substrate. The average thickness of the obtained coating film was about 1 μm, but there was some unevenness in the thickness.

Claims

1. A method for producing an aqueous fluoropolymer solution, comprising: carrying out polymerization of a monomer (I) represented by general formula (I) in an aqueous medium to produce an aqueous solution containing a fluoropolymer of the monomer (I), wherein the oxygen concentration in the reaction system of the polymerization is maintained at 500 ppm by volume or less. General formula (I): CX ２ = CY - CF ２ -O-Rf-A (Wherein, X and Y are independently H, F, CH ３ or CF ３ and at least one of X and Y is F. Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. A is -COOM, -SO ３ M, -OSO ３ M or -C(CF ３ ) ２ OM (M is H, metal atom, NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium; R ７ is H or an organic group.

2. The process according to claim 1, wherein the polymerization of the monomer (I) is carried out at a polymerization temperature of 20°C to 59°C.

3. 3. The process according to claim 1, wherein the polymerization of the monomer (I) is carried out in the presence of a polymerization initiator, and the polymerization initiator is a persulfate.

4. The method according to any one of claims 1 to 3, wherein the polymerization of the monomer (I) is carried out in the presence of a polymerization initiator, and a total amount of the polymerization initiator used in the polymerization is 0.00001 to 10 mass% relative to the aqueous medium.

5. The method according to any one of claims 1 to 4, wherein the amount of the monomer containing the monomer (I) present at the start of polymerization is 40 mass% or more based on the amount of the aqueous medium present.

6. The method according to any one of claims 1 to 5, wherein the content of the polymerized units (I) based on the monomer (I) in the fluoropolymer is 50 mol% or more based on the total polymerized units constituting the fluoropolymer.

7. The method according to any one of claims 1 to 6, wherein the content of the polymerization unit (I) based on the monomer (I) in the fluoropolymer is 99 mol% or more based on the total polymerization units constituting the fluoropolymer.

8. The weight average molecular weight (Mw) of the fluoropolymer is 20.0×10 ４ The method for producing according to any one of claims 1 to 7.

9. The weight average molecular weight (Mw) of the fluoropolymer is 40.0×10 ４ The method for producing according to any one of claims 1 to 8.

10. The number average molecular weight (Mn) of the fluoropolymer is 8.0×10 ４ The method for producing according to any one of claims 1 to 9.

11. The method according to any one of claims 1 to 10, wherein after the polymerization is completed, the composition containing the aqueous medium and the fluoropolymer is recovered, and the composition is treated by at least one means selected from the group consisting of ultrafiltration, microfiltration, dialysis membrane treatment, liquid separation and reprecipitation.

12. An aqueous solution containing a fluoropolymer of a monomer (I) represented by general formula (I), The content of the polymerization unit (I) based on the monomer (I) in the fluoropolymer is 50 mol % or more based on the total polymerization units constituting the fluoropolymer, The weight average molecular weight (Mw) of the fluoropolymer is 40.0×10 ４ That's all. Substantially free of dimers and trimers of monomer (I) Aqueous fluoropolymer solutions. General formula (I): CX ２ = CY - CF ２ -O-Rf-A (Wherein, X and Y are independently H, F, CH ３ or CF ３ and at least one of X and Y is F. Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. A is -COOM, -SO ３ M, -OSO ３ M or -C(CF ３ ) ２ OM (M is H, metal atom, NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium; R ７ is H or an organic group.

13. The number average molecular weight (Mn) of the fluoropolymer is 8.0 x 10 ４ The fluoropolymer aqueous solution according to claim 12 .

14. The fluoropolymer aqueous solution according to claim 12 or 13, wherein the content of the polymerized units (I) in the fluoropolymer is 99 mol % or more relative to all polymerized units constituting the fluoropolymer.

15. The fluoropolymer aqueous solution according to any one of claims 12 to 14, wherein the content of the fluoropolymer is 2% by mass or more based on the aqueous fluoropolymer solution.

16. A coating composition comprising the aqueous fluoropolymer solution according to any one of claims 12 to 15.

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