Fluorine-containing polymers and methods for their manufacture

Abstract

The present invention provides a fluoropolymer, which is a fluoropolymer of a monomer (I) represented by the general formula (I). Among them, based on all the polymer units constituting the above fluoropolymer, the content of the polymer unit (I) based on the monomer (I) is 40 mol% or more, and the weight-average molecular weight (Mw) is 1.4×10 4 or more. General formula (I): CX2=CX‑O‑Rf‑A (wherein, X is independently F or CF3, and Rf is a fluoroalkylene group having 1 to 40 carbon atoms, or a fluoroalkylene group having 2 to 100 carbon atoms and having an ether bond or a ketone group. A is -COOM, -SO3M, -OSO3M or -C(CF3)2OM (M is -H, a metal atom, -NR 7 4, an imidazolium with or without substituents, a pyridinium with or without substituents, or a phosphonium with or without substituents, and R 7 is H or an organic group).).

Description

Technical Field

[0001] The present disclosure relates to a fluoropolymer and a method for producing the same. Background Art

[0002] In Patent Document 1, regarding a coating composition useful as a composition for forming an antireflection film in lithography, a coating composition is described which is characterized by containing a fluoropolymer (A) and a solvent, and the fluoropolymer (A) has a unit represented by the following formula (1) and a number average molecular weight of 1,000 to 7,500.

[0003] -[CX 1 X 2 -CY(-Rf-COOM)]-···(1)

[0004] (In the formula, X 1 and X 2 each independently represent a hydrogen atom, a fluorine atom or a chlorine atom, Y represents a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group or a trifluoromethyl group, Rf represents a branched perfluoroalkylene group which may contain an etheric oxygen atom between carbon-carbon atoms, or represents a branched oxyperfluoroalkylene group which may contain an etheric oxygen atom between carbon-carbon atoms, and M represents a hydrogen atom or an ammonium ion which may or may not have a substituent.)

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: International Publication No. 2015 / 080061 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] An object of the present disclosure is to provide a new fluoropolymer which has a high molecular weight despite containing a large amount of polymerization units based on a monomer having a specific structure.

[0010] Further, an object of the present disclosure is to provide a method for producing a fluoropolymer having a high molecular weight even when a large amount of polymerization units based on a monomer having a specific structure are introduced into the fluoropolymer.

[0011] Means for Solving the Problems

[0012] According to the present disclosure, there is provided a fluoropolymer which is a fluoropolymer of a monomer (I) represented by the general formula (I), wherein, with respect to all the polymerization units constituting the above fluoropolymer, the content of the polymerization unit (I) based on the monomer (I) is 40 mol% or more, and the weight average molecular weight (Mw) of the polymer is 1.4×10 4 or more.

[0013] General formula (I): CX2=CX-O-Rf-A

[0014] (In the formula, X is independently F or CF3, Rf is a fluoroalkylene group having 1 to 40 carbon atoms, or a fluoroalkylene group having 2 to 100 carbon atoms and having an ether bond or a keto group. A is -COOM, -SO3M, -OSO3M or -C(CF3)2OM (M is -H, a metal atom, -NR 7 4. Imidazolium with or without substituents, pyridinium with or without substituents, or phosphonium with or without substituents, R 7 is H or an organic group).)

[0015] The fluoropolymer of the present disclosure preferably has a weight average molecular weight (Mw) of 1.9×10 4 or more.

[0016] The fluoropolymer of the present disclosure preferably has a molecular weight distribution (Mw / Mn) of 3.0 or less.

[0017] In general formula (I), preferably both X are F.

[0018] In general formula (I), preferably Rf is a fluoroalkylene group having 1 to 5 carbon atoms, or a fluoroalkylene group having 2 to 5 carbon atoms and having an ether bond or a keto group.

[0019] In general formula (I), preferably A is -COOM.

[0020] The fluoropolymer of the present disclosure is preferably a copolymer of monomer (I) and 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).

[0021] When the fluoropolymer of the present disclosure is a copolymer, preferably: based on all the polymerization units constituting the above fluoropolymer, the content of the polymerization unit (I) based on monomer (I) is 40 to 60 mol%; based on all the polymerization units constituting the above fluoropolymer, the content of the polymerization unit (M) based on the 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 60 to 40 mol%.

[0022] When the fluoropolymer of the present disclosure is a copolymer, the alternation rate of the polymerization unit (I) and the polymerization unit (M) is preferably 40% or more.

[0023] In the fluoropolymer of the present disclosure, preferably based on all the polymerization units constituting the above fluoropolymer, the content of the polymerization unit (I) is 99 mol% or more.

[0024] The fluoropolymer of the present disclosure preferably substantially does not contain dimers and trimers of monomer (I).

[0025] In the fluoropolymer of the present disclosure, the content of the fraction having a molecular weight of 3000 or less is preferably 3.7% or less based on the fluoropolymer.

[0026] In addition, according to the present disclosure, there is provided an aqueous solution containing the fluoropolymer described in any one of claims 1 to 10.

[0027] In the aqueous solution of the present disclosure, the content of the above fluoropolymer is preferably 2% by mass or more based on the above aqueous solution.

[0028] In addition, according to the present disclosure, there is provided a coating composition containing the above fluoropolymer or the above aqueous solution.

[0029] In addition, according to the present disclosure, there is provided a method for producing a fluoropolymer, which is a method for producing a fluoropolymer of monomer (I) by polymerizing monomer (I) represented by the general formula (I), wherein the oxygen concentration in the reaction system of the above polymerization is maintained at 1500 volume ppm or less.

[0030] General formula (I): CX2 = CX - O - Rf - A

[0031] (In the formula, X is independently F or CF3, Rf is a fluoroalkylene group having 1 to 40 carbon atoms, or a fluoroalkylene group having an ether bond or a ketone group and having 2 to 100 carbon atoms. A is -COOM, -SO3M, -OSO3M or -C(CF3)2OM (M is -H, a metal atom, -NR 7 4, an imidazolium with or without substituents, a pyridinium with or without substituents or a phosphonium with or without substituents, R 7 is H or an organic group).)

[0032] In the production method of the present disclosure, the polymerization of monomer (I) is preferably carried out at a polymerization temperature of 70 °C or lower.

[0033] In the production method of the present disclosure, the polymerization of monomer (I) can be carried out in an aqueous medium.

[0034] In the production method of the present disclosure, the polymerization of monomer (I) is preferably carried out in the presence of a polymerization initiator, and the above polymerization initiator is a persulfate.

[0035] In the production method of the present disclosure, the polymerization of monomer (I) is preferably carried out in the presence of a polymerization initiator, and the above polymerization initiator is added at the start of polymerization and also during polymerization.

[0036] In the production method of the present disclosure, the polymerization of monomer (I) is preferably carried out in an aqueous medium in the presence of a polymerization initiator, and the total addition amount of the polymerization initiator used in the above polymerization is 0.00001 to 10% by mass based on the above aqueous medium.

[0037] In the production method of the present disclosure, the polymerization of monomer (I) is preferably carried out in an aqueous medium, and the amount of the monomer containing monomer (I) present at the start of polymerization is 40% by mass or more based on the amount of the above aqueous medium present.

[0038] In the production method of the present disclosure, based on all the polymerization units constituting the fluoropolymer, the content of the polymerization unit (I) based on monomer (I) in the fluoropolymer is preferably 40 mol% or more.

[0039] In the production method of the present disclosure, the weight average molecular weight (Mw) of the fluoropolymer is preferably 1.4×10 4 or more.

[0040] In the production method of the present disclosure, the polymerization of monomer (I) is preferably carried out in an aqueous medium. After the polymerization is completed, a composition containing the above aqueous medium and the fluoropolymer is recovered, and the above composition is treated by at least one means selected from the group consisting of ultrafiltration, microfiltration, dialysis membrane treatment, liquid separation, and reprecipitation.

[0041] In the production method of the present disclosure, the polymerization of monomer (I) can be carried out in the absence of an aqueous medium.

[0042] When the polymerization of monomer (I) is carried out in the absence of an aqueous medium, the polymerization of monomer (I) is preferably carried out in the presence of a polymerization initiator, and the above polymerization initiator is a peroxide.

[0043] When the polymerization of monomer (I) is carried out in the absence of an aqueous medium, based on all the polymerization units constituting the fluoropolymer, the content of the polymerization unit (I) based on monomer (I) in the fluoropolymer is preferably 40 mol% or more.

[0044] When the polymerization of monomer (I) is carried out in the absence of an aqueous medium, the weight average molecular weight (Mw) of the fluoropolymer is preferably 1.4×10 4 or more.

[0045] When the polymerization of monomer (I) is carried out in the absence of an aqueous medium, it is preferable to recover the composition containing the fluoropolymer after the polymerization is completed, mix the above composition with an aqueous medium, and treat the composition containing the above aqueous medium and the fluoropolymer by at least one means selected from the group consisting of ultrafiltration, microfiltration, dialysis membrane treatment, liquid separation, and reprecipitation.

[0046] Effects of the Invention

[0047] According to the present disclosure, it is possible to provide a novel fluoropolymer which has a high molecular weight despite containing a large amount of polymerization units based on monomers having a specific structure.

[0048] In addition, according to the present disclosure, there is provided a method for producing a fluoropolymer having a high molecular weight even when a large amount of polymerization units based on monomers having a specific structure are introduced into the fluoropolymer. Detailed Description of the Invention

[0049] The following provides a detailed description of the specific embodiments of the present disclosure, but the present disclosure is not limited to the following embodiments.

[0050] Before specifically describing the present disclosure, some terms used in the present disclosure are defined or explained.

[0051] In the present disclosure, an "organic group" means a group containing one or more carbon atoms, or a group formed by removing one hydrogen atom from an organic compound.

[0052] Examples of such "organic groups" include:

[0053] an alkyl group which may have one or more substituents,

[0054] an alkenyl group which may have one or more substituents,

[0055] an alkynyl group which may have one or more substituents,

[0056] a cycloalkyl group which may have one or more substituents,

[0057] a cycloalkenyl group which may have one or more substituents,

[0058] a cyclo-dienyl group which may have one or more substituents,

[0059] an aryl group which may have one or more substituents,

[0060] an aralkyl group which may have one or more substituents,

[0061] a non-aromatic heterocyclic group which may have one or more substituents,

[0062] a heteroaryl group which may have one or more substituents,

[0063] cyano group,

[0064] formyl group,

[0065] RaO-,

[0066] RaCO-,

[0067] RaSO2−,

[0068] RaCOO−,

[0069] RaNRaCO−,

[0070] RaCONRa−,

[0071] RaOCO−,

[0072] RaOSO2−, and

[0073] RaNRbSO2−

[0074] (In these formulas, Ra is independently:

[0075] alkyl which may have one or more substituents,

[0076] alkenyl which may have one or more substituents,

[0077] alkynyl which may have one or more substituents,

[0078] cycloalkyl which may have one or more substituents,

[0079] cycloalkenyl which may have one or more substituents,

[0080] cyclodienyl which may have one or more substituents,

[0081] aryl which may have one or more substituents,

[0082] aralkyl which may have one or more substituents,

[0083] non-aromatic heterocyclic group which may have one or more substituents, or

[0084] heteroaryl which may have one or more substituents,

[0085] Rb is independently H or alkyl which may have one or more substituents).

[0086] As the above organic group, alkyl which may have one or more substituents is preferred.

[0087] In addition, in the present disclosure, a "substituent" refers to a group capable of substitution. Examples of such "substituents" include: aliphatic groups, aromatic groups, heterocyclic groups, acyl groups, acyloxy groups, acylamino groups, aliphatic oxy groups, aromatic oxy groups, heterocyclic oxy groups, aliphatic oxycarbonyl groups, aromatic oxycarbonyl groups, heterocyclic oxycarbonyl groups, carbamoyl groups, aliphatic sulfonyl groups, aromatic sulfonyl groups, heterocyclic sulfonyl groups, aliphatic sulfonyloxy groups, aromatic sulfonyloxy groups, heterocyclic sulfonyloxy groups, sulfamoyl groups, aliphatic sulfonamide groups, aromatic sulfonamide groups, heterocyclic sulfonamide groups, amino groups, aliphatic amino groups, aromatic amino groups, heterocyclic amino groups, aliphatic oxycarbonylamino groups, aromatic oxycarbonylamino groups, heterocyclic oxycarbonylamino groups, aliphatic sulfinyl groups, aromatic sulfinyl groups, aliphatic thio groups, aromatic thio groups, hydroxy groups, cyano groups, sulfo groups, carboxy groups, aliphatic oxyamino groups, aromatic oxyamino groups, carbamoylamino groups, sulfamoylamino groups, halogen atoms, sulfamoylcarbamoyl groups, carbamoylsulfamoyl groups, bis-aliphatic oxyphosphinyl groups, and bis-aromatic oxyphosphinyl groups.

[0088] The above-mentioned aliphatic group can be saturated or unsaturated, and in addition, it can 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. As the above-mentioned aliphatic group, an alkyl group having 1 to 8 carbon atoms in total, preferably 1 to 4 carbon atoms, such as a methyl group, an ethyl group, a vinyl group, a cyclohexyl group, a carbamoylmethyl group, etc., can be mentioned.

[0089] The above-mentioned aromatic group can 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. As the above-mentioned aromatic group, an aryl group 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, a 4-methylsulfonylphenyl group, etc., can be mentioned.

[0090] The above-mentioned heterocyclic group can 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. As the above-mentioned heterocyclic group, a 5- to 6-membered heterocycle having 2 to 12 carbon atoms in total, preferably 2 to 10 carbon atoms, such as a 2-tetrahydrofuranyl group, a 2-pyrimidinyl group, etc., can be mentioned.

[0091] The above-mentioned acyl group can 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. As the above-mentioned acyl group, an acyl group having 2 to 8 carbon atoms in total, preferably 2 to 4 carbon atoms, such as an acetyl group, a propionyl group, a benzoyl group, a 3-pyridinecarbonyl group, etc., can be mentioned.

[0092] The above-mentioned acylamino group may have an aliphatic group, an aromatic group, a heterocyclic group, etc. For example, it may have an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propionylamino group, etc. As the above-mentioned acylamino group, an acylamino group having 2 to 12 carbon atoms in total, preferably 2 to 8 carbon atoms in total, an alkylcarbonylamino group having 2 to 8 carbon atoms in total, such as an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propionylamino group, etc. can be mentioned.

[0093] The above-mentioned aliphatic oxycarbonyl group may be saturated or unsaturated. In addition, it may have a hydroxyl 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. As the above-mentioned aliphatic oxycarbonyl group, an alkoxycarbonyl group having 2 to 8 carbon atoms in total, preferably 2 to 4 carbon atoms in total, such as a methoxycarbonyl group, an ethoxycarbonyl group, a (tert)butoxycarbonyl group, etc. can be mentioned.

[0094] The above-mentioned carbamoyl group may have an aliphatic group, an aromatic group, a heterocyclic group, etc. As the above-mentioned carbamoyl group, an unsubstituted carbamoyl group, an alkylcarbamoyl group having 2 to 9 carbon atoms in total, preferably an unsubstituted carbamoyl group, an alkylcarbamoyl group having 2 to 5 carbon atoms in total, such as an N-methylcarbamoyl group, an N,N-dimethylcarbamoyl group, an N-phenylcarbamoyl group, etc. can be mentioned.

[0095] The above-mentioned aliphatic sulfonyl group may be saturated or unsaturated. In addition, it may have a hydroxyl 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. As the above-mentioned aliphatic sulfonyl group, an alkylsulfonyl group having 1 to 6 carbon atoms in total, preferably 1 to 4 carbon atoms in total, such as a methanesulfonyl group, etc. can be mentioned.

[0096] The above-mentioned aromatic sulfonyl group may have a hydroxyl 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. As the above-mentioned aromatic sulfonyl group, an arylsulfonyl group having 6 to 10 carbon atoms in total, such as a benzenesulfonyl group, etc. can be mentioned.

[0097] The above-mentioned amino group may have an aliphatic group, an aromatic group, a heterocyclic group, etc.

[0098] The above-mentioned acylamino group may have, for example, an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propionylamino group, etc. As the above-mentioned acylamino group, an acylamino group having 2 to 12 carbon atoms in total, preferably 2 to 8 carbon atoms in total, more preferably an alkylcarbonylamino group having 2 to 8 carbon atoms in total, such as an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propionylamino group, etc. can be mentioned.

[0099] The above-mentioned aliphatic sulfonamido group, aromatic sulfonamido group, heterocyclic sulfonamido group can be, for example, methylsulfonamido group, benzenesulfonamido group, 2-pyridinesulfonamido group, etc.

[0100] The above-mentioned sulfamoyl group can have an aliphatic group, an aromatic group, a heterocyclic group, etc. Examples of the above-mentioned sulfamoyl group include sulfamoyl group, alkylsulfamoyl group having 1 to 9 carbon atoms in total, dialkylsulfamoyl group having 2 to 10 carbon atoms in total, arylsulfamoyl group having 7 to 13 carbon atoms in total, heterocyclic sulfamoyl group having 2 to 12 carbon atoms in total. More preferably, it is sulfamoyl group, alkylsulfamoyl group having 1 to 7 carbon atoms in total, dialkylsulfamoyl group having 3 to 6 carbon atoms in total, arylsulfamoyl group having 6 to 11 carbon atoms in total, heterocyclic sulfamoyl group having 2 to 10 carbon atoms in total, such as sulfamoyl group, methylsulfamoyl group, N,N-dimethylsulfamoyl group, phenylsulfamoyl group, 4-pyridinesulfamoyl group, etc.

[0101] The above-mentioned aliphatic oxy group can be saturated or unsaturated, and can also have methoxy group, ethoxy group, isopropoxy group, cyclohexyloxy group, methoxyethoxy group, etc. Examples of the above-mentioned aliphatic oxy group include alkoxy groups having 1 to 8 carbon atoms in total, preferably 1 to 6 carbon atoms in total, such as methoxy group, ethoxy group, isopropoxy group, cyclohexyloxy group, methoxyethoxy group, etc.

[0102] The above-mentioned aromatic amino group and heterocyclic amino group can have an aliphatic group, an aliphatic oxy group, a halogen atom, a carbamoyl group, a heterocyclic group fused to the aryl group, an aliphatic oxycarbonyl group. Preferably, it can have 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, an aliphatic oxycarbonyl group having 2 to 4 carbon atoms in total.

[0103] The above-mentioned aliphatic thio group can be saturated or unsaturated, and can also have an alkylthio group having 1 to 8 carbon atoms in total, more preferably 1 to 6 carbon atoms in total, such as methylthio group, ethylthio group, carbamoylmethylthio group, tert-butylthio group, etc.

[0104] The above-mentioned carbamoyl amino group may have an aliphatic group, an aryl group, a heterocyclic group, etc. Examples of the above-mentioned carbamoyl amino group include carbamoyl amino group, alkylcarbamoyl amino group having 2 to 9 carbon atoms in total, dialkylcarbamoyl amino group having 3 to 10 carbon atoms in total, arylcarbamoyl amino group having 7 to 13 carbon atoms in total, and heterocyclic carbamoyl amino group having 3 to 12 carbon atoms in total. Preferred are carbamoyl amino group, alkylcarbamoyl amino group having 2 to 7 carbon atoms in total, dialkylcarbamoyl amino group having 3 to 6 carbon atoms in total, arylcarbamoyl amino group having 7 to 11 carbon atoms in total, and heterocyclic carbamoyl amino group having 3 to 10 carbon atoms in total. For example, carbamoyl amino group, methylcarbamoyl amino group, N,N-dimethylcarbamoyl amino group, phenylcarbamoyl amino group, 4-pyridylcarbamoyl amino group, etc.

[0105] In the present disclosure, the range represented by the end points includes all the values included in the range (for example, 1 to 10 includes 1.4, 1.9, 2.33, 5.75, 9.98, etc.).

[0106] In the present disclosure, the description of "at least 1" includes all the values of 1 or more (for example, 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.).

[0107] Next, the fluoropolymer of the present disclosure will be specifically described.

[0108] The fluoropolymer of the present disclosure is a polymer of monomer (I) represented by general formula (I).

[0109] General formula (I): CX2=CX-O-Rf-A

[0110] (In the formula, X is independently F or CF3, Rf is a fluoroalkylene group having 1 to 40 carbon atoms, or a fluoroalkylene group having 2 to 100 carbon atoms and having an ether bond or a keto group. A is -COOM, -SO3M, -OSO3M or -C(CF3)2OM (M is -H, a metal atom, -NR 7 4, imidazolium with or without substituents, pyridinium with or without substituents or phosphonium with or without substituents, R 7 is H or an organic group).)

[0111] In the fluoropolymer of the present disclosure, based on all the polymerization units constituting the above-mentioned fluoropolymer, the content of the polymerization unit (I) based on monomer (I) is 40 mol% or more, and the weight average molecular weight (Mw) is 1.4×10 4 or more. The fluoropolymer of the present disclosure is a new fluoropolymer having a high molecular weight despite containing a large amount of polymerization unit (I).

[0112] The fluoropolymer may be a homopolymer composed only of the polymerization unit (I) based on the monomer (I), or may be a copolymer containing the polymerization unit (I) and the polymerization unit based on other monomers capable of copolymerizing with the monomer (I). The polymerization unit (I) may be the same or different in each occurrence, and the fluoropolymer may contain the polymerization unit (I) based on monomers represented by two or more different general formulas (I).

[0113] As the content of the polymerization unit (I) in the fluoropolymer, relative to all the polymerization units constituting the fluoropolymer, it is preferably 40 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, 99 mol% or more in sequence. 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). When the content of the polymerization unit (I) in the fluoropolymer is large, it has the advantage of increased water solubility of the fluoropolymer.

[0114] In the fluoropolymer, as the content of the polymerization unit based on other monomers capable of copolymerizing with the monomer (I), relative to all the polymerization units constituting the fluoropolymer, it is preferably 60 mol% or less, 50 mol% or less, 40 mol% or less, 30 mol% or less, 20 mol% or less, 10 mol% or less, 1 mol% or less in sequence. The content of the polymerization unit based on other monomers capable of copolymerizing with the monomer (I) is particularly preferably substantially 0 mol%, and most preferably the fluoropolymer does not contain the polymerization unit based on other monomers.

[0115] As the lower limit of the weight-average molecular weight (Mw) of the fluoropolymer, it is preferably 1.4×10 4 or more, 1.7×10 4 or more, 1.9×10 4 or more, 2.1×10 4 or more, 2.3×10 4 or more, 2.7×10 4 or more, 3.1×10 4 or more, 3.5×10 4 or more, 3.9×10 4 or more, 4.3×10 4 or more, 4.7×10 4 or more, 5.1×10 4 or more. As the upper limit of the weight-average molecular weight (Mw) of the fluoropolymer, it is preferably 150.0×10 4 or less, 100.0×10 4 or less, 60.0×10 4 or less, 50.0×10 4 or less, 40.0×104 The following.

[0116] As the lower limit of the number-average molecular weight (Mn) of the fluoropolymer, it is preferably 0.7×10 4 or more, 0.9×10 4 or more, 1.0×10 4 or more, 1.2×10 4 or more, 1.4×10 4 or more, 1.6×10 4 or more, 1.8×10 4 or more. As the upper limit of the number-average molecular weight (Mn) of the fluoropolymer, it is preferably 75.0×10 4 or less, 50.0×10 4 or less, 40.0×10 4 or less, 30.0×10 4 , 20.0×10 4 or less.

[0117] The molecular weight distribution (Mw / Mn) of the fluoropolymer is preferably 3.0 or less, more preferably 2.7 or less, further preferably 2.4 or less, still further preferably 2.2 or less, particularly preferably 2.0 or less, and most preferably 1.9 or less.

[0118] The number-average molecular weight and the weight-average molecular weight are values obtained by calculating the molecular weight using monodisperse polyethylene oxide (PEO) and polyethylene glycol (PEG) as standards by gel permeation chromatography (GPC). In addition, in the case where measurement by GPC is not possible, the number-average molecular weight of the fluoropolymer can be obtained 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 according to JIS K7210.

[0119] Monomer (I) is represented by the general formula (I).

[0120] General formula (I): CX2=CX-O-Rf-A

[0121] In the formula, X is independently F or CF3. Preferably, at least 1 or more of X is F, and more preferably all X are F.

[0122] In the formula, Rf is a fluoroalkylene group having 1 to 40 carbon atoms, a fluoroalkylene group having an ether bond and having 2 to 100 carbon atoms, or a fluoroalkylene group having a keto group and having 2 to 100 carbon atoms. The fluoroalkylene group having an ether bond and having 2 to 100 carbon atoms does not include a structure with an oxygen atom at the end, and is an alkylene group containing an ether bond between carbon-carbon atoms.

[0123] The number of carbon atoms of the above-mentioned fluoroalkylene group is preferably 2 or more. Additionally, the number of carbon atoms of the above-mentioned fluoroalkylene group is preferably 30 or less, more preferably 20 or less, further preferably 10 or less, and particularly preferably 5 or less. Examples of the above-mentioned fluoroalkylene group include -CF2-, -CH2CF2-, -CF2CF2-, -CF2CH2-, -CF2CF2CH2-, -CF(CF3)-, -CF(CF3)CF2-, -CF(CF3)CH2-, -CF2CF2CF2-, CF2CF2CF2CF2-, etc. The above-mentioned fluoroalkylene group is preferably a perfluoroalkylene group, and preferably an unbranched linear perfluoroalkylene group.

[0124] The number of carbon atoms of the above-mentioned fluoroalkylene group having an ether bond is preferably 3 or more. Additionally, the number of carbon atoms of the above-mentioned fluoroalkylene group having an ether bond is preferably 60 or less, more preferably 30 or less, further preferably 12 or less, and particularly preferably 5 or less. The above-mentioned fluoroalkylene group having an ether bond is also preferably, for example, a divalent group represented by the general formula:

[0125]

[0126] (In the formula, Z 1 is F or CF3; Z 2 and Z 3 are each H or F; Z 4 is H, F or CF3; p1 + q1 + r1 is an integer from 1 to 10; s1 is 0 or 1; t1 is an integer from 0 to 5).

[0127] Specific examples of the above-mentioned fluoroalkylene group having an ether bond include -CF2CF(CF3)OCF2CF2-, -CF(CF3)CF2 - O - CF(CF3)-, -(CF(CF3)CF2 - O) n -CF(CF3)-(where n is an integer from 1 to 10), -CF(CF3)CF2 - O - CF(CF3)CH2-, -(CF(CF3)CF2 - O) n -CF(CF3)CH2-(where n is an integer from 1 to 10), -CH2CF2CF2O - CH2CF2CH2-, -CF2CF2CF2O - CF2-, -CF2CF2CF2O - CF2CF2-, -CF2CF2CF2O - CF2CF2CF2-, -CF2CF2CF2O - CF2CF2CH2-, -CF2CF2O - CF2-, -CF2CF2O - CF2CH2-, etc. The above-mentioned fluoroalkylene group having an ether bond is preferably a perfluoroalkylene group.

[0128] The number of carbon atoms of the fluoroalkylene group having a keto group is preferably 3 or more. In addition, the number of carbon atoms of the fluoroalkylene group having a keto group is preferably 60 or less, more preferably 30 or less, still more preferably 12 or less, and particularly preferably 5 or less.

[0129] As the fluoroalkylene group having a keto group, specifically, -CF2CF(CF3)CO-CF2-, -CF2CF(CF3)CO-CF2CF2-, -CF2CF(CF3)CO-CF2CF2CF2-, -CF2CF(CF3)CO-CF2CF2CF2CF2- and the like can be mentioned. The fluoroalkylene group having a keto group is preferably a perfluoroalkylene group.

[0130] In the formula, A is -COOM, -SO3M, -OSO3M or -C(CF3)2OM. As A, -COOM or -SO3M is preferred, and -COOM is more preferred. The fluoropolymer of the present disclosure may be a fluoropolymer containing both a polymerization unit (I) in which A is -COOM and a polymerization unit (I) in which A is -SO3M.

[0131] M is H, a metal atom, NR 7 4, an imidazolium having or not having a substituent, a pyridinium having or not having a substituent, or a phosphonium having or not having a substituent, R 7 is H or an organic group.

[0132] As the metal atom, alkali metals (Group 1), alkaline earth metals (Group 2), etc. can be mentioned, and Na, K or Li is preferred.

[0133] As M, H, a metal atom or NR 7 4 is preferred, and H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or NR 7 4 is more preferred, H, Na, K, Li or NH4 is still more preferred, H, Na, K or NH4 is further more preferred, H, Na or NH4 is particularly preferred, and H or NH4 is most preferred. As R 7 , H or a C1-10 organic group is preferred, and H or a C 1-4 organic group is more preferred, and H or a C 1-4 alkyl group is still more preferred.

[0134] As the monomer (I), at least one selected from the group consisting of monomers represented by the general formulas (1a), (1b), (1c), (1d), (1e), (1f) and (1g) is preferred for the reason of further improving the water solubility of the fluoropolymer.

[0135] CF2=CF-O-(CF2) n1 -A(1a)

[0136] (In the formula, n1 represents an integer from 1 to 10, and A is the same as above.)

[0137] CF2=CF-O-(CF2C(CF3)F) n2 -A(1b)

[0138] (In the formula, n2 represents an integer from 1 to 5, and A has the same definition as above.)

[0139] CF2=CF-O-(CFX 1 ) n3 -A(1c)

[0140] (In the formula, X 1 represents F or CF3, n3 represents an integer from 1 to 10, and A has the same definition as above.)

[0141] CF2=CF-O-(CF2CFX 1 O) n4 -(CF2) n6 -A(1d)

[0142] (In the formula, n4 represents an integer from 1 to 10, n6 represents an integer from 1 to 3, and A and X 1 have the same definition as above.)

[0143] CF2=CF-O-(CF2CF2CFX 1 O) n5 -CF2CF2CF2-A(1e)

[0144] (In the formula, n5 represents an integer from 0 to 10, and A and X 1 have the same definition as above.)

[0145] CF2=CF-O-(CF2) n7 -O-(CF2) n8 -A(1f)

[0146] (In the formula, n7 represents an integer from 1 to 10, n8 represents an integer from 1 to 3. A has the same definition as above.)

[0147] CF2=CF[OCF2CF(CF3)] n9 O(CF2) n10 O[CF(CF3)CF2O] n11 CF(CF3)-A(1g)

[0148] (In the formula, n9 represents an integer from 0 to 5, n10 represents an integer from 1 to 8, n11 represents an integer from 0 to 5. A has the same definition as above.)

[0149] In general formula (1a), n1 above is preferably an integer of 5 or less, more preferably an integer of 3 or less, and still more preferably an integer of 2 or less. A above is preferably -COOM or -SO3M, more preferably -COOM. M above is preferably H, Na, K, or NH4.

[0150] Examples of the monomer represented by general formula (1a) include CF2=CF-O-CF2COOM, CF2=CF-O-CF2SO3M, CF2=CF(OCF2CF2COOM), CF2=CF(OCF2CF2SO3M), CF2=CF(O(CF2)3COOM), CF2=CF(O(CF2)3SO3M), CF2=CFO(CF)4SO3M (wherein M is as defined above).

[0151] In general formula (1b), n2 is preferably an integer of 3 or less. A above is preferably -COOM or -SO3M, more preferably -COOM. M above is preferably H, Na, K, or NH4.

[0152] In general formula (1c), n3 is preferably an integer of 5 or less, and A above is preferably -COOM or -SO3M, more preferably -COOM. M above is preferably H, Na, K, or NH4.

[0153] In general formula (1d), X 1 is preferably CF3, n4 is preferably an integer of 5 or less, and A is preferably -COOM or -SO3M, more preferably -COOM. M is preferably H, Na, K, or NH4.

[0154] Examples of the monomer represented by general formula (1d) include CF2=CFOCF2CF(CF3)OCF2CF2COOM, CF2=CFOCF2CF(CF3)OCF2CF2SO3M, CF2=CFOCF2CF(CF3)OCF2COOM, CF2=CFOCF2CF(CF3)OCF2SO3M, CF2=CFOCF2CF(CF3)OCF2CF2CF2COOM, CF2=CFOCF2CF(CF3)OCF2CF2CF2SO3M (wherein M represents H, NH4, or an alkali metal).

[0155] In general formula (1e), n5 is preferably an integer of 5 or less, and A is preferably -COOM or -SO3M, more preferably -COOM. M is preferably H, Na, K, or NH4.

[0156] As the monomer represented by the general formula (1e), for example, CF2=CFOCF2CF2CF2COOM and CF2=CFOCF2CF2CF2SO3M (wherein M represents H, NH4 or an alkali metal) can be cited.

[0157] In the general formula (1f), n7 is preferably an integer of 5 or less, A is preferably -COOM or -SO3M, more preferably -COOM. M is preferably H, Na, K or NH4.

[0158] As the monomer represented by the general formula (1f), for example, CF2=CF-O-(CF2)3-O-CF2-COOM (wherein M represents H, NH4 or an alkali metal) can be cited.

[0159] In the general formula (1g), n9 is preferably an integer of 3 or less, n10 is preferably an integer of 3 or less, n11 is preferably an integer of 3 or less, A is preferably -COOM or -SO3M, more preferably -COOM. M is preferably H, Na, K or NH4.

[0160] As the monomer represented by the general formula (1g), for example, CF2=CFO(CF2)2OCF(CF3)COOM, CF2=CFOCF2CF2OCF(CF3)CF2OCF(CF3)COOM, CF2=CFOCF2CF(CF3)OCF2CF2OCF(CF3)COOM, CF2=CF[OCF2CF(CF3)]2O(CF2)2O[CF(CF3)CF2O]CF(CF3)COOM, CF2=CF[OCF2CF(CF3)]3O(CF2)2O[CF(CF3)CF2O]3CF(CF3)COOM (wherein M represents H, NH4 or an alkali metal) can be cited.

[0161] As other monomers capable of copolymerizing with the monomer (I), monomers represented by the general formula CFR=CR2 (wherein R is independently H, F or a perfluoroalkyl group having 1 to 4 carbon atoms) are preferred. In addition, as other monomers capable of copolymerizing with the monomer (I), fluorinated ethylenically unsaturated monomers having 2 or 3 carbon atoms are preferred. As other monomers capable of copolymerizing with the monomer (I), for example, CF2=CF2, CF2=CFCl, CH2=CF2, CFH=CH2, CFH=CF2, CF2=CFCF3, CH2=CFCF3, CH2=CHCF3, CHF=CHCF3 (E isomer), CHF=CHCF3 (Z isomer), etc. can be cited.

[0162] As other monomers, from the viewpoint of good copolymerizability, at least one selected from the group consisting of tetrafluoroethylene (CF2═CF2), chlorotrifluoroethylene (CF2═CFCl), and vinylidene fluoride (CH2═CF2) is preferred, and at least one selected from the group consisting of tetrafluoroethylene and vinylidene fluoride is more preferred, and vinylidene fluoride is further preferred. The polymerization units based on the above other monomers may be the same or different in each occurrence, and the fluoropolymer may contain polymerization units based on two or more different other monomers. Therefore, the polymerization units based on the other monomers are preferably at least one selected from the group consisting of the polymerization units based on tetrafluoroethylene and the polymerization units based on vinylidene fluoride, and more preferably the polymerization units based on vinylidene fluoride. The polymerization units based on the other monomers may be the same or different in each occurrence, and the fluoropolymer may contain polymerization units based on two or more different other monomers.

[0163] When the fluoropolymer has the polymerization unit (I) and the polymerization units based on other monomers capable of copolymerizing with the monomer (I), the content of the polymerization unit (I) based on the monomer (I) is preferably 40 to 60 mol%, more preferably 45 to 55 mol%, relative to all the polymerization units constituting the fluoropolymer, and the content of the polymerization units based on the other monomers is preferably 60 to 40 mol%, more preferably 55 to 45 mol%, relative to all the polymerization units constituting the fluoropolymer. Such a constitution is particularly suitable when the polymerization units based on other monomers capable of copolymerizing with the monomer (I) are the polymerization units (M) based on the monomers represented by the general formula CFR═CR2.

[0164] When the fluoropolymer contains the polymerization unit (I) and the polymerization units based on other monomers capable of copolymerizing with the monomer (I), the alternation rate of the polymerization unit (I) and the polymerization units based on other monomers capable of copolymerizing with the monomer (I) is preferably 40% or more, more preferably 50% or more, further preferably 60% or more, still further preferably 70% or more, particularly preferably 80% or more, and most preferably 90% or more. The alternation rate can be, for example, 40 to 99%. Such a constitution is particularly suitable when the polymerization units based on other monomers capable of copolymerizing with the monomer (I) are the polymerization units (M) based on the monomers represented by the general formula CFR═CR2.

[0165] The alternation rate of the polymerization unit (I) and the polymerization units based on other monomers capable of copolymerizing with the monomer (I) in the fluoropolymer can be determined by 19 19F-NMR analysis of the fluoropolymer.

[0166] As other monomers, the general formula (n1-2) can also be cited:

[0167] [Chemical formula 2]

[0168]

[0169] (wherein, X 1 , X 2 are the same or different and are 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 fluoroalkyl group having 1 to 40 carbon atoms or a fluoroalkyl group having an ether bond and having 2 to 100 carbon atoms) represented monomer.

[0170] Specifically, preferably, 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 (wherein, Rf 3 is the same as the above formula (n1-2)) and the like.

[0171] As the above other monomer, a formula (n2-1) can also be cited:

[0172] [Chemical formula 3]

[0173]

[0174] (wherein, X 9 is H, F or CH3; Rf 4 is a fluoroalkyl group having 1 to 40 carbon atoms or a fluoroalkyl group having an ether bond and having 2 to 100 carbon atoms) represented fluoroacrylate monomer. The above Rf 4 group can be cited:

[0175] [Chemical formula 4]

[0176]

[0177] (wherein, Z 8 is H, F or Cl; d1 is an integer of 1 to 4; e1 is an integer of 1 to 10),

[0178]

[0179] (wherein, e2 is an integer of 1 to),

[0180]

[0181] (wherein, d3 is an integer of 1 to 4; e3 is an integer of 1 to 10), etc.

[0182] As the above-mentioned other monomers, the formula (n2-2) can also be cited:

[0183] CH2=CHO-Rf 5 (n2-2)

[0184] (wherein, Rf 5 is a fluoroalkyl group having 1 to 40 carbon atoms or a fluoroalkyl group having an ether bond and 2 to 100 carbon atoms) represented by the fluorovinyl ether.

[0185] As the monomer of the general formula (n2-2), specifically, preferably, the following can be cited:

[0186] [Chemical formula 5]

[0187]

[0188] (wherein, Z 9 is H or F; e4 is an integer of 1 to 10),

[0189]

[0190] (wherein, e5 is an integer of 1 to 10),

[0191]

[0192] (wherein, e6 is an integer of 1 to 10), etc.

[0193] More specifically, the following can be cited:

[0194] [Chemical formula 6]

[0195] CH2=CHOCH2CF2CF2H,

[0196]

[0197]

[0198] CH2=CHOCH2CF2CF3,

[0199] CH2=CHOCH2CF3,

[0200]

[0201]

[0202] etc.

[0203] In addition to the above, the general formula (n2-3) can also be cited:

[0204] CH2=CHCH2O-Rf 6 (n2-3)

[0205] (wherein, Rf 6 is a fluoroalkyl group having 1 to 40 carbon atoms or a fluoroalkyl group having an ether bond and 2 to 100 carbon atoms) the fluoroallyl ether represented by the general formula (n2-4):

[0206] CH2=CH-Rf 7 (n2-4)

[0207] (wherein, Rf 7 is a fluoroalkyl group having 1 to 40 carbon atoms or a fluoroalkyl group having an ether bond and 2 to 100 carbon atoms) the fluoro vinyl monomer represented by etc.

[0208] As the monomers represented by the general formulas (n2-3) and (n2-4), specifically, examples thereof include:

[0209] [Chemical formula 7]

[0210] CH2=CHCH2OCH2CF2CF2H,

[0211]

[0212]

[0213] CH2=CHCH2OCH2CF2CF3,

[0214] CH2=CHCH2OCH2CF3,

[0215]

[0216] and other monomers.

[0217] Fluoropolymers generally have end groups. The end groups are the end groups generated during polymerization. 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 1 pendant heteroatom. The number of carbon atoms of the alkyl or fluoroalkyl group is preferably 1 to 20. These end groups are usually generated by an initiator or a chain transfer agent used in the formation of the fluoropolymer, or are generated in a chain transfer reaction.

[0218] The fluoropolymer preferably has an ion exchange rate (IXR) of 53 or less. The above IXR is defined as the number of carbon atoms in the polymer main chain relative to the ionic groups. The precursor groups that become ionic by hydrolysis (e.g., -SO2F) are not regarded as ionic groups for determining the IXR.

[0219] IXR is preferably 0.5 or more, more preferably 1 or more, further preferably 3 or more, still further preferably 4 or more, particularly still further preferably 5 or more, and especially preferably 8 or more. In addition, IXR is more preferably 43 or less, further preferably 33 or less, and especially preferably 23 or less.

[0220] As the ion exchange capacity of the fluoropolymer, it is preferably 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, greater than 2.20 meq / g, 2.50 meq / g or more, 2.60 meq / g or more, 3.00 meq / g or more, 3.50 meq / g or more in sequence. The ion exchange capacity is the content of ionic groups (anionic groups) of the fluoropolymer, and is obtained by calculation based on the composition of the fluoropolymer.

[0221] In the fluoropolymer, the ionic groups (anionic groups) are typically distributed along the polymer main chain. The fluoropolymer preferably contains, in addition to the polymer main chain, repeating side chains bonded to the main chain, and the side chains have ionic groups.

[0222] The fluoropolymer preferably contains ionic groups having a pKa of less than 10, more preferably less than 7. The ionic groups of the fluoropolymer are preferably selected from the group consisting of sulfonates, carboxylates, phosphonates, and phosphates.

[0223] The terms "sulfonates, carboxylates, phosphonates, and phosphates" refer to their respective salts or their respective acids capable of forming salts. When using salts, it is preferred that the salts are alkali metal salts or ammonium salts. The preferred ionic group is a sulfonate group.

[0224] The fluoropolymer preferably has water solubility. Water solubility refers to the property of being easily dissolved or dispersed in an aqueous medium. A fluoropolymer having water solubility, for example, cannot be used to measure the particle size by dynamic light scattering method (DLS). On the other hand, a fluoropolymer having non-water solubility, for example, can be used to measure the particle size by dynamic light scattering method (DLS).

[0225] An aqueous solution containing a fluoropolymer and an aqueous medium can also be used for various purposes. As the content of the fluoropolymer in the aqueous solution, it is preferably 0.1% by mass or more, more preferably 1.0% by mass or more, further preferably 1.5% by mass or more, especially preferably 2.0% by mass or more, and preferably 20% by mass or less, more preferably 15% by mass or less, relative to the aqueous solution.

[0226] The fluoropolymer or the aqueous solution containing the fluoropolymer may substantially not contain the dimers and trimers of monomer (I). The dimers and trimers of monomer (I) are usually generated when monomer (I) is polymerized to obtain the fluoropolymer. As the content of the dimers and trimers in the fluoropolymer, it is 1.0% by mass or less, preferably 0.1% by mass or less, more preferably 0.01% by mass or less, further preferably 0.001% by mass or less, particularly preferably 0.0001% by mass or less, relative to the fluoropolymer.

[0227] The content of the dimers and trimers in the fluoropolymer can be determined as follows: Perform gel permeation chromatography (GPC) analysis of the fluoropolymer, and calculate the ratio (area percentage) of the total area of the peaks in the chromatogram obtained by GPC analysis to the total area of the peaks of the dimers and trimers, thereby determining the content.

[0228] In addition, when the content of the dimers and trimers in the fluoropolymer is less than 0.5% by mass relative to the fluoropolymer, it can be determined by measurement using liquid chromatography - mass spectrometry (LC / MS).

[0229] Specifically, prepare aqueous solutions with 5 or more levels of the content of monomer (I), perform LC / MS analysis on each content, plot the relationship between the content and the area of the region (integral value of the peak) relative to the content, and prepare a calibration curve of monomer (I). Furthermore, prepare calibration curves of the dimers and trimers of monomer (I) from the calibration curve of monomer (I).

[0230] Add methanol to the fluoropolymer to prepare a mixture, filter it using an ultrafiltration disc (molecular weight cut-off 3000 Da), and perform LC / MS analysis on the obtained recovered liquid.

[0231] After that, using the calibration curve, the area of the region (integral value of the peak) of the chromatogram of the dimers and trimers of monomer (I) can be converted into the content of the dimers and trimers.

[0232] The content of the fraction with a molecular weight of 3000 or less in the fluoropolymer or the aqueous solution containing the fluoropolymer can be 3.7% or less, preferably 3.2% or less, further preferably 2.7% or less, still further preferably 1.7% or less, particularly further preferably 1.2% or less, particularly preferably 1.0% or less, and most preferably 0.6% or less, relative to the fluoropolymer. The lower limit of the content of the fraction with a molecular weight of 3000 or less is not limited, for example, it is 0.01%. The content of the fraction with a molecular weight of 3000 or less can be calculated from the peak area of GPC. The fraction with a molecular weight of 3000 or less includes all compounds with a molecular weight of 3000 or less.

[0233] The content of the fraction with a molecular weight of 2000 or less in the fluoropolymer or the aqueous solution containing the fluoropolymer may be 3.2% or less, preferably 2.7% or less, more preferably 2.2% or less, still more preferably 1.7% or less, particularly more preferably 1.2% or less, and particularly preferably 0.6% or less, relative to the fluoropolymer. The lower limit of the content of the fraction with a molecular weight of 2000 or less is not limited and is, for example, 0.01%. The content of the fraction with a molecular weight of 2000 or less can be calculated from the peak area of GPC. The fraction with a molecular weight of 2000 or less includes all compounds with a molecular weight of 2000 or less.

[0234] The content of the fraction with a molecular weight of 1500 or less in the fluoropolymer or the aqueous solution containing the fluoropolymer may be 2.7% or less, preferably 2.2% or less, more preferably 1.7% or less, still more preferably 1.2% or less, particularly more preferably 0.6% or less, relative to the fluoropolymer. The lower limit of the content of the fraction with a molecular weight of 1500 or less is not limited and is, for example, 0.01%. The content of the fraction with a molecular weight of 1500 or less can be calculated from the peak area of GPC. The fraction with a molecular weight of 1500 or less includes all compounds with a molecular weight of 1500 or less.

[0235] The content of the fraction with a molecular weight of 1000 or less in the fluoropolymer or the aqueous solution containing the fluoropolymer may be 2.2% or less, preferably 1.7% or less, more preferably 1.2% or less, still more preferably 0.6% or less, relative to the fluoropolymer. The lower limit of the content of the fraction with a molecular weight of 1000 or less is not limited and is, for example, 0.01%. The content of the fraction with a molecular weight of 1000 or less can be calculated from the peak area of GPC. The fraction with a molecular weight of 1000 or less includes all compounds with a molecular weight of 1000 or less.

[0236] The fluoropolymer or the aqueous solution containing the fluoropolymer preferably substantially does not contain a fluorosurfactant. In the present disclosure, "substantially does not contain a fluorosurfactant" means that the content of the fluorosurfactant 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, further preferably 10 mass ppb or less, still further preferably 1 mass ppb or less, and particularly preferably less than the detection limit for the fluorosurfactant measured by liquid chromatography - mass spectrometry (LC / MS).

[0237] The content of the fluorosurfactant can be quantified by a known method. For example, it can be quantified by LC / MS analysis.

[0238] First, methanol is added to the fluoropolymer or aqueous solution, followed by extraction, and the resulting extract is analyzed by LC / MS. To further improve the extraction efficiency, treatments such as Soxhlet extraction and ultrasonic treatment can be carried out.

[0239] Based on the LC / MS mass spectrum obtained, the molecular weight information is selected, and the consistency with the structural formula of the candidate fluorosurfactant is confirmed.

[0240] Subsequently, aqueous solutions with five or more levels of the confirmed fluorosurfactant content are prepared, and LC / MS analysis is performed on the aqueous solutions of each content. A calibration curve is plotted by graphing the relationship between the content and the area of the region relative to that content.

[0241] After that, using the calibration curve, the area of the region of the LC / MS chromatogram of the fluorosurfactant in the extract can be converted into the content of the fluorosurfactant.

[0242] The description regarding the polymerization of the fluorosurfactant and monomer (I) is described below.

[0243] The fluoropolymer or the aqueous solution containing the fluoropolymer can be used for various purposes. Since the fluoropolymer has a high molecular weight, the fluoropolymer or the aqueous solution containing the fluoropolymer can be suitably used as a component of, for example, a coating composition.

[0244] The coating composition is preferably a composition composed of 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 showing excellent antireflection effect can be formed. By using a coating composition containing a fluoropolymer having a large number of polymerization units (I) and a high molecular weight, a uniform coating film with a desired film thickness can be easily formed, and the antireflection effect and hydrophilicity of the obtained coating film can be improved, and a sufficient developer dissolution rate can be obtained. In addition, the higher the content of the polymerization unit (I) in the fluoropolymer, the more the low refractive index property and excellent developer solubility can be imparted to the coating film, and thus it is preferred.

[0245] The solvent contained in the coating composition is at least one selected from the group consisting of water and alcohol. As the alcohol, a lower alcohol having 1 to 6 carbon atoms is preferred, and at least one selected from the group consisting of methanol, ethanol, isopropyl alcohol, n-propanol, and butanol is more preferred.

[0246] 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 absorber, a storage stabilizer, a preservative, an adhesion aid, a dye, etc.

[0247] The content of the fluoropolymer in the coating composition is preferably 0.1 to 50% by mass, more preferably 0.5 to 30% by mass, still more preferably 1 to 20% by mass, and particularly preferably 2 to 10% by mass, relative to the coating composition.

[0248] By coating the coating composition onto a substrate, a coating film can be produced. The coating method of the coating composition is not particularly limited, and examples thereof include a roll coating method, a casting method, an impregnation method, a spin coating method, a water casting method, a die coating method, a Langmuir Blodgett method, and the like.

[0249] Examples of the substrate onto which the coating composition is coated include a silicon wafer, quartz glass, and the like.

[0250] Particularly in the case where strict film thickness control is required, it is suitable to perform coating by the spin coating method. In the case of 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, and the like. Regarding the characteristics of the apparatus (spin coater), if the rotation speed is too slow and the rotation time is too short, film thickness unevenness is likely to occur. Therefore, coating is usually performed at a high rotation speed and for a certain period of time.

[0251] However, when the coating composition is coated at a high rotation speed and for a certain period of time, the resulting film thickness decreases. Therefore, it is not easy to produce a relatively thick film while suppressing film thickness unevenness by using the spin coating method. In the coating composition of the present disclosure, since the fluoropolymer has a high molecular weight even when the content of the polymerization unit (I) in the fluoropolymer is large, excellent effects such as hydrophilicity can be imparted to the coating film, and a relatively thick film can be easily produced while suppressing film thickness unevenness.

[0252] The coating film obtained from the coating composition is suitable as, for example, a topcoat film and an antireflection film. For example, by coating the coating composition on a photoresist layer, a photoresist laminate having a photoresist layer and an antireflection film can be produced.

[0253] The fluoropolymer and the aqueous solution containing the fluoropolymer can be appropriately produced by the production method of the present disclosure. Next, the production methods of the fluoropolymer and the aqueous solution containing the fluoropolymer will be described.

[0254] The production method of the present disclosure is a production method of a fluoropolymer that produces a fluoropolymer of monomer (I) by polymerizing monomer (I).

[0255] In the production method of the present disclosure, when polymerizing monomer (I), the oxygen concentration in the polymerization reaction system is maintained at 1500 volume ppm or less. By selecting such polymerization conditions, the molecular weight of the fluoropolymer of monomer (I) can be increased.

[0256] In existing manufacturing methods, when a large amount of polymerization units (I) based on monomer (I) are introduced into a fluoropolymer, it is impossible to manufacture a fluoropolymer with a high molecular weight. According to the manufacturing method of the present disclosure, it is possible to introduce polymerization units (I) that are 40 mol% or more relative to all the polymerization units constituting the fluoropolymer, and at the same time, it is possible to increase the weight-average molecular weight (Mw) of the fluoropolymer to 1.4×10 4 or more.

[0257] The oxygen concentration in the polymerization reaction system is 1500 volume ppm or less. In the manufacturing method of the present disclosure, the oxygen concentration in the reaction system is maintained at 1500 volume ppm or less throughout the polymerization of monomer (I). The oxygen concentration in the reaction system is preferably 500 volume ppm or less, more preferably 100 volume ppm or less, and further preferably 50 volume ppm or less. In addition, the oxygen concentration in the reaction system is usually 0.01 volume ppm or more.

[0258] The oxygen concentration in the polymerization reaction system can be controlled, for example, by introducing an inert gas such as nitrogen or argon, or in the case of using a gaseous monomer, by flowing the gaseous monomer into the liquid phase or gas phase of the reactor. The oxygen concentration in the polymerization reaction system can be determined by measuring and analyzing the gas discharged from the exhaust pipeline of the polymerization system using a low-concentration oxygen analyzer.

[0259] For the reason that it is possible to easily manufacture a fluoropolymer with a higher molecular weight, the polymerization temperature of monomer (I) is preferably 70°C or less, more preferably 65°C or less, further preferably 60°C or less, further preferably 55°C or less, particularly further preferably 50°C or less, especially preferably 45°C or less, and most preferably 40°C or less, and preferably 10°C or more, more preferably 15°C or more, and further preferably 20°C or more.

[0260] In the manufacturing method of the present disclosure, monomer (I) can be copolymerized with the above-mentioned other monomers.

[0261] In the manufacturing method of the present disclosure, polymerization can be carried out in the presence of a pH regulator. The pH regulator can be added before the start of polymerization or after the start of polymerization.

[0262] As the pH regulator, ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium phosphate, potassium phosphate, sodium citrate, potassium citrate, ammonium citrate, sodium gluconate, potassium gluconate, ammonium gluconate, etc. can be used. The above pH can be measured using a pH meter manufactured by Orion Corporation.

[0263] The polymerization pressure is generally atmospheric pressure to 10 MPaG. The polymerization pressure is appropriately determined according to the type of monomer used, the molecular weight of the target fluoropolymer, and the reaction rate.

[0264] The polymerization time is generally 1 to 200 hours, and can also be 5 to 100 hours.

[0265] In the production method of the present disclosure, the polymerization of monomer (I) can be carried out in an aqueous medium or in the absence of an aqueous medium. Further, in the absence of an aqueous medium, that is, in the presence of a non-aqueous medium (such as an organic solvent such as toluene) having a content of less than 10% by mass based on the amount of the monomer containing monomer (I), the polymerization of monomer (I) can be carried out. The polymerization of monomer (I) can be emulsion polymerization or suspension polymerization, or can also be bulk polymerization.

[0266] The aqueous medium refers to a liquid containing water as the reaction medium for polymerization. The aqueous medium is not particularly limited as long as it contains water, and may contain water, and non-fluorinated organic solvents such as alcohols, ethers, and ketones and / or fluorinated organic solvents having a boiling point of 40°C or lower. As the aqueous medium, water is preferably used.

[0267] In the production method of the present disclosure, the polymerization of monomer (I) can be carried out in the presence of a polymerization initiator. As the polymerization initiator, as long as free radicals can be generated in the above polymerization temperature range, there is no particular limitation, and known oil-soluble and / or water-soluble polymerization initiators can be used. Further, it can also be combined with a reducing agent or the like to initiate polymerization in the form of redox. The concentration of the polymerization initiator is appropriately determined according to the type of monomer, the molecular weight of the target fluoropolymer, and the reaction rate. When the polymerization of monomer (I) is carried out in an aqueous medium, a water-soluble polymerization initiator such as persulfate is preferably used. When the polymerization of monomer (I) is carried out in the absence of an aqueous medium, an oil-soluble polymerization initiator such as peroxide is preferably used.

[0268] As the polymerization initiator, persulfates (such as ammonium persulfate), organic peroxides such as diperoxysuccinic acid and diperoxyglutaric acid can be used alone or in the form of a mixture of these. In addition, it can also be used in combination with a reducing agent such as sodium sulfite to form a redox system. Further, during polymerization, a radical scavenger such as hydroquinone or catechol can also be added, or a peroxide decomposer such as ammonium sulfite can be added to adjust the free radical concentration in the system.

[0269] As the polymerization initiator, from the perspective of being able to easily produce a fluoropolymer with a higher molecular weight, persulfate is preferred. As persulfates, ammonium persulfate, potassium persulfate, sodium persulfate, etc. can be mentioned, and ammonium persulfate is preferred.

[0270] As the polymerization initiator, an oil-soluble radical polymerization initiator can be used. As the oil-soluble radical polymerization initiator, known oil-soluble peroxides can be used. For example, the following peroxides can be cited as representative substances: dialkyl peroxydicarbonates such as diisopropyl peroxydicarbonate and di-sec-butyl peroxydicarbonate; peresters such as tert-butyl peroxydiisobutyrate and tert-butyl peroxypivalate; dialkyl peroxides such as di-tert-butyl peroxide; and bis(ω-hydroperfluorocapronyl) peroxide, bis(ω-hydroperfluoroheptanoyl) peroxide, bis(ω-hydroperfluorononanoyl) peroxide, bis(perfluorobutyryl) peroxide, bis(perfluorovaleryl) peroxide, bis(perfluorohexanoyl) peroxide, bis(perfluoroheptanoyl) peroxide, bis(perfluorooctanoyl) peroxide, bis(perfluorononanoyl) peroxide, bis(ω-chloroperfluorohexanoyl) peroxide, bis(ω-chloroperfluorooctanoyl) peroxide, ω-hydroperfluoroheptanoyl-ω-hydroperfluorononanoyl peroxide, ω-chloroperfluorohexanoyl-ω-chloroperfluorooctanoyl peroxide, ω-hydroperfluoroheptanoyl-perfluorobutyryl peroxide, bis(dichloroperfluorobutyryl) peroxide, bis(trichloroperfluorohexanoyl) peroxide, bis(tetrachloroperfluorooctanoyl) peroxide, bis(pentachloroperfluorodecanoyl) peroxide, bis(undecachlorotritriacontadodecanoyl) peroxide, and other bis[perfluoro(or fluorochloro)acyl] peroxides; and so on.

[0271] The addition amount of the polymerization initiator is not particularly limited, and an amount sufficient to prevent a significant decrease in the polymerization rate (for example, several ppm relative to the water concentration) may be added all at once, successively, or continuously at the initial stage of polymerization. The upper limit is in the range where the heat of polymerization can be removed from the surface of the apparatus while increasing the reaction temperature. A more preferable upper limit is in the range where the heat of polymerization can be removed from the surface of the apparatus.

[0272] In the production method of the present disclosure, the polymerization initiator can be added at the start of polymerization and also during polymerization. As the ratio of the addition amount of the polymerization initiator added at the start of polymerization to the addition amount of the polymerization initiator added during polymerization, it is preferably 95 / 5 to 5 / 95, more preferably 60 / 40 to 10 / 90, and further preferably 30 / 70 to 15 / 85. The addition method of the polymerization initiator added during polymerization is not particularly limited, and it can be added in one total amount, divided into two or more portions, or continuously added.

[0273] In the production method of the present disclosure, for the reason that a fluoropolymer with a higher molecular weight can be easily produced, the total addition amount of the polymerization initiator used in the polymerization is preferably 0.00001 to 10% by mass relative to the aqueous medium. As the total addition amount of the polymerization initiator used in the polymerization, it is preferably 0.0001% by mass or more, more preferably 0.001% by mass or more, still more preferably 0.01% by mass or more, and preferably 5% by mass or less, more preferably 2% by mass or less.

[0274] In the production method of the present disclosure, for the reason that a fluoropolymer with a higher molecular weight can be easily produced, the total addition amount of the polymerization initiator used in the polymerization is preferably 0.001 to 10 mol% relative to the total addition amount of the monomers used in the polymerization. As the total addition amount of the polymerization initiator used in the polymerization, it is more preferably 0.005 mol% or more, still more preferably 0.01 mol% or more, and more preferably 10 mol% or less, still more preferably 5.0 mol% or less, particularly still more preferably 2.5 mol% or less, especially most preferably 2.2 mol% or less, and preferably 2.0 mol% or less.

[0275] In the production method of the present disclosure, for the reason that a fluoropolymer with a higher molecular weight can be easily produced, the amount of the monomers containing monomer (I) present at the start of the polymerization is preferably 30% by mass or more relative to the amount of the aqueous medium present. As the amount of the monomers present, it is more preferably 35% by mass or more, still more preferably 40% by mass or more. The upper limit of the amount of the monomers present is not particularly limited, and from the aspect of smoothly carrying out the polymerization, it can be 200% by mass or less. The amount of the monomers present at the start of the polymerization refers to the total amount of monomer (I) present in the reactor at the start of the polymerization and other monomers when other monomers are present.

[0276] When polymerizing monomer (I) in the absence of an aqueous medium, the total addition amount of a polymerization initiator such as a peroxide is preferably 0.001 to 10 mol% relative to the total amount of the monomers containing monomer (I) (monomer mixture). As the total addition amount of the polymerization initiator used in the polymerization, it is more preferably 0.005 mol% or more, still more preferably 0.01 mol% or more, and more preferably 10 mol% or less, still more preferably 5.0 mol% or less, particularly still more preferably 2.5 mol% or less, especially most preferably 2.2 mol% or less, and preferably 2.0 mol% or less.

[0277] The polymerization of monomer (I) can be carried out as follows: Charge an aqueous medium, monomer (I), and other monomers and other additives as necessary into a reactor, stir the contents of the reactor, and maintain the reactor at a specified polymerization temperature. Then add a specified amount of a polymerization initiator to initiate the polymerization reaction, thereby carrying out the polymerization. After the start of the polymerization reaction, monomers, a polymerization initiator, and other additives can be added according to the purpose.

[0278] The polymerization of monomer (I) can be carried out in the substantial absence of a fluorosurfactant. "In the substantial absence of a fluorosurfactant" in the present disclosure means that the amount of the fluorosurfactant relative to the aqueous medium is 10 mass ppm or less. As the amount of the fluorosurfactant relative to the aqueous medium, it is preferably 1 mass ppm or less, more preferably 100 mass ppb or less, still more preferably 10 mass ppb or less, and even more preferably 1 mass ppb or less.

[0279] Examples of the above-mentioned fluorosurfactant include anionic fluorosurfactants. The above-mentioned anionic fluorosurfactant can be, for example, a surfactant containing fluorine atoms and having a total carbon atom number of 20 or less in the part other than the anionic group.

[0280] As the above-mentioned fluorosurfactant, it can also be a fluorine-containing surfactant having a molecular weight of the anionic part of 800 or less.

[0281] It should be noted that the above-mentioned "anionic part" refers to the part of the above-mentioned fluorosurfactant other than the cation. For example, in the case of F(CF2) n1 COOM represented by the following formula (I), it is the part of "F(CF2) n1 COO".

[0282] As the above-mentioned fluorosurfactant, a fluorosurfactant having a LogPOW of 3.5 or less can also be cited. The above-mentioned LogPOW is the partition coefficient of 1-octanol and water, and is represented by LogP [where P represents the ratio of the concentration of the fluorosurfactant in octanol to the concentration of the fluorosurfactant in water when phase separation occurs in an octanol / water (1:1) mixed solution containing the fluorosurfactant].

[0283] The above-mentioned LogPOW is calculated as follows: On a column: TOSOH ODS-120T column ( Under the conditions of using an eluent produced by Tosoh Corporation, acetonitrile / 0.6 mass% HClO4 aqueous solution = 1 / 1 (vol / vol%), flow rate: 1.0 ml / minute, sample volume: 300 μL, column temperature: 40°C, and detection light: UV 210 nm, HPLC was performed on standard substances (heptanoic acid, octanoic acid, nonanoic acid, and decanoic acid) with known octanol / water partition coefficients to create a calibration curve of each elution time and the known octanol / water partition coefficient. Based on this calibration curve, calculations were made according to the elution time of HPLC in the sample solution.

[0284] As the above-mentioned fluorosurfactant, specifically, 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. 3250808, U.S. Patent No. 3271341, Japanese Patent Application Laid-Open No. 2003-119204, International Publication No. 2005 / 042593, International Publication No. 2008 / 060461, International Publication No. 2007 / 046377, Japanese Patent Application Laid-Open No. 2007-119526, International Publication No. 2007 / 046482, International Publication No. 2007 / 046345, U.S. Patent Application Publication No. 2014 / 0228531, International Publication No. 2013 / 189824, International Publication No. 2013 / 189826, etc.

[0285] As the above-mentioned anionic fluorosurfactant, the following general formula (N 0 ) can be cited:

[0286] X n0 -Rf n0 -Y 0 (N 0 )

[0287] (In the formula, X n0 is H, Cl, or / and F. Rf n0 is an alkylene group with 3 to 20 carbon atoms, linear, branched, or cyclic, in which part or all of the H is replaced by F, and the alkylene group may contain one or more ether bonds, and part of the H may be replaced by Cl. Y 0 is an anionic group) represents a compound.

[0288] Y 0The anionic group can be -COOM, -SO2M or -SO3M, or can be -COOM or -SO3M.

[0289] M is H, a metal atom, NR 7 4, an imidazolium with or without substituents, a pyridinium with or without substituents, or a phosphonium with or without substituents, R 7 is H or an organic group.

[0290] As the above-mentioned metal atom, an alkali metal (Group 1), an alkaline earth metal (Group 2), etc. can be cited. For example, it is Na, K or Li.

[0291] As R 7 , it can be H or a C 1-10 organic group, or can be H or a C 1-4 organic group, or can also be H or a C 1-4 alkyl group.

[0292] M can be H, a metal atom or NR 7 4, or can be H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or NR 7 4, or can also be H, Na, K, Li or NH4.

[0293] In the above-mentioned Rf n0 , more than 50% of H can be substituted by fluorine.

[0294] As the compound represented by the above general formula (N 0 ), the following can be cited:

[0295] The following general formula (N 1 ):

[0296] X n0 -(CF2) m1 -Y 0 (N 1 )

[0297] (In the formula, X n0 is H, Cl and F, m1 is an integer from 3 to 15, Y 0 is the group defined above) the compound represented; the following general formula (N 2 ):

[0298] Rf n1 -O-(CF(CF3)CF2O) m2 CFX n1 -Y 0 (N 2 )

[0299] (In the formula, Rf n1is a perfluoroalkyl group having 1 to 5 carbon atoms, m2 is an integer of 0 to 3, X n1 is F or CF3, Y 0 is a compound represented by the group defined above); the following general formula (N 3 ):

[0300] Rf n2 (CH2) m3 -(Rf n3 ) q -Y 0 (N 3 )

[0301] (In the formula, Rf n2 is a partially or fully fluorinated alkyl group having 1 to 13 carbon atoms that 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, Y 0 is a compound represented by the group defined above); the following general formula (N 4 ):

[0302] Rf n4 -O-(CY n1 Y n2 ) p CF2-Y 0 (N 4 )

[0303] (In the formula, Rf n4 is a linear or branched partially or fully fluorinated alkyl group having 1 to 12 carbon atoms that 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, Y 0 is a compound represented by the group defined above); and the general formula (N 5 ):

[0304] [Chemical formula 8]

[0305]

[0306] (In the formula, X n2 、X n3 and X n4 may be the same or different and are H, F, or a linear or branched partially or fully fluorinated alkyl group having 1 to 6 carbon atoms that may contain an ether bond. Rf n5 is a linear or branched partially or fully fluorinated alkylene group having 1 to 3 carbon atoms that may contain an ether bond, L is a linking group, Y 0 is a compound represented by the group defined above. Among them, X n2 、Xn3 , X n4 and Rf n5 a compound represented by a total carbon atom number of 18 or less).

[0307] As the compound represented by the above general formula (N 0 ), more specifically, the following can be mentioned: perfluorocarboxylic acid (I) represented by the following general formula (I), ω-H perfluorocarboxylic acid (II) represented by the following general formula (II), perfluoroether carboxylic acid (III) represented by the following general formula (III), perfluoroalkylalkylene carboxylic acid (IV) represented by the following general formula (IV), perfluoroalkoxyfluorocarboxylic acid (V) represented by the following general formula (V), perfluoroalkylsulfonic acid (VI) represented by the following general formula (VI), ω-H perfluorosulfonic acid (VII) represented by the following general formula (VII), perfluoroalkylalkylene sulfonic acid (VIII) represented by the following general formula (VIII), alkylalkylene carboxylic acid (IX) represented by the following general formula (IX), fluorocarboxylic acid (X) represented by the following general formula (X), alkoxyfluorosulfonic acid (XI) represented by the following general formula (XI), compound (XII) represented by the following general formula (XII), compound (XIII) represented by the following general formula (XIII), etc.

[0308] The above perfluorocarboxylic acid (I) is represented by the following general formula (I)

[0309] F(CF2) n1 COOM (I)

[0310] (wherein, n1 is an integer of 3 to 14, and M is H, a metal atom, NR 7 4, imidazolium with or without substituents, pyridinium with or without substituents, or phosphonium with or without substituents, and R 7 is H or an organic group).

[0311] The above ω-H perfluorocarboxylic acid (II) is represented by the following general formula (II)

[0312] H(CF2) n2 COOM (II)

[0313] (wherein, n2 is an integer of 4 to 15, and M is the group defined above).

[0314] The above perfluoroether carboxylic acid (III) is represented by the following general formula (III)

[0315] Rf 1 -O-(CF(CF3)CF2O) n3 CF(CF3)COOM (III)

[0316] (wherein, Rf1 is a perfluoroalkyl group having 1 to 5 carbon atoms, n3 is an integer of 0 to 3, and M is the group defined above).

[0317] The above perfluoroalkylalkylene carboxylic acid (IV) is represented by the following general formula (IV)

[0318] Rf 2 (CH2) n4 Rf 3 COOM (IV)

[0319] (In the formula, Rf 2 is a perfluoroalkyl group having 1 to 5 carbon atoms, 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 the group defined above).

[0320] The above alkoxyfluorocarboxylic acid (V) is represented by the following general formula (V)

[0321] Rf 4 -O-CY 1 Y 2 CF2-COOM (V)

[0322] (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 the group defined above).

[0323] The above perfluoroalkylsulfonic acid (VI) is represented by the following general formula (VI)

[0324] F(CF2) n5 SO3M (VI)

[0325] (In the formula, n5 is an integer of 3 to 14, and M is the group defined above).

[0326] The above ω-H perfluoroalkylsulfonic acid (VII) is represented by the following general formula (VII)

[0327] H(CF2) n6 SO3M (VII)

[0328] (In the formula, n6 is an integer of 4 to 14, and M is the group defined above).

[0329] The above perfluoroalkylalkylene sulfonic acid (VIII) is represented by the following general formula (VIII)

[0330] Rf 5 (CH2)n7 SO3M (VIII)

[0331] (wherein, Rf 5 is a perfluoroalkyl group having 1 to 13 carbon atoms, n7 is an integer of 1 to 3, and M is the group defined above).

[0332] The above-mentioned alkylalkylene carboxylic acid (IX) is represented by the following general formula (IX)

[0333] Rf 6 (CH2) n8 COOM (IX)

[0334] (wherein, Rf 6 is a linear or branched, partially or fully fluorinated alkyl group having 1 to 13 carbon atoms and may contain an ether bond, n8 is an integer of 1 to 3, and M is the group defined above).

[0335] The above-mentioned fluoro carboxylic acid (X) is represented by the following general formula (X)

[0336] Rf 7 -O-Rf 8 -O-CF2-COOM (X)

[0337] (wherein, Rf 7 is a linear or branched, partially or fully fluorinated alkyl group having 1 to 6 carbon atoms and 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 the group defined above).

[0338] The above-mentioned alkoxy fluorosulfonic acid (XI) is represented by the following general formula (XI)

[0339] Rf 9 -O-CY 1 Y 2 CF2-SO3M (XI)

[0340] (wherein, Rf 9 is a linear or branched, partially or fully fluorinated alkyl group having 1 to 12 carbon atoms and may contain an ether bond, may contain chlorine, Y 1 and Y 2 are the same or different and are H or F, and M is the group defined above).

[0341] The above-mentioned compound (XII) is represented by the following general formula (XII):

[0342] [Chemical Formula 9]

[0343]

[0344] (wherein X 1 , X 2 , and X 3 may be the same or different and are H, F, or a linear or branched, partially or fully fluorinated alkyl group having 1 to 6 carbon atoms and may contain an ether bond, Rf 10 is a perfluoroalkylene group having 1 to 3 carbon atoms, L is a linking group, and Y 0 is an anionic group).

[0345] Y 0 may be -COOM, -SO2M, or -SO3M, or may be -SO3M or COOM (wherein M is the group defined above).

[0346] As L, for example, a single bond, a partially or fully fluorinated alkylene group having 1 to 10 carbon atoms and may contain an ether bond can be cited.

[0347] The above compound (XIII) is represented by the following general formula (XIII):

[0348] Rf 11 -O-(CF2CF(CF3)O) n9 (CF2O) n10 CF2COOM (XIII)

[0349] (wherein Rf 11 is a fluoroalkyl group having 1 to 5 carbon atoms and containing chlorine, n9 is an integer of 0 to 3, n10 is an integer of 0 to 3, and M is the group defined above). As the compound (XIII), CF2ClO(CF2CF(CF3)O) n9 (CF2O) n10 CF2COONH4 (a mixture with an average molecular weight of 750, and n9 and n10 in the formula are the groups defined above).

[0350] As described above, as the above anionic fluorosurfactant, carboxylic acid surfactants, sulfonic acid surfactants, etc. can be cited.

[0351] The fluorosurfactant may be one kind of fluorosurfactant or a mixture containing two or more kinds of fluorosurfactants.

[0352] As the fluorosurfactant, compounds represented by the following formula can be cited. The fluorosurfactant may also be a mixture of these compounds. In one embodiment of the above polymerization, the monomer (I) is polymerized in the substantial absence of the compound represented by the following formula.

[0353] F(CF2)7COOM,

[0354] F(CF2)5COOM,

[0355] H(CF2)6COOM,

[0356] H(CF2)7COOM,

[0357] CF3O(CF2)3OCHFCF2COOM,

[0358] C3F7OCF(CF3)CF2OCF(CF3)COOM,

[0359] CF3CF2CF2OCF(CF3)COOM,

[0360] CF3CF2OCF2CF2OCF2COOM,

[0361] C2F5OCF(CF3)CF2OCF(CF3)COOM,

[0362] CF3OCF(CF3)CF2OCF(CF3)COOM,

[0363] CF2ClCF2CF2OCF(CF3)CF2OCF2COOM,

[0364] CF2ClCF2CF2OCF2CF(CF3)OCF2COOM,

[0365] CF2ClCF(CF3)OCF(CF3)CF2OCF2COOM,

[0366] CF2ClCF(CF3)OCF2CF(CF3)OCF2COOM,

[0367] [Chemical Formula 10]

[0368]

[0369] (In each formula, M is H, a metal atom, NR 7 4, an imidazolium with or without substituents, a pyridinium with or without substituents, or a phosphonium with or without substituents, and R 7 is H or an organic group.)

[0370] In the production method of the present disclosure, since the polymerization of monomer (I) is carried out in an aqueous medium, an aqueous solution containing a fluoropolymer and an aqueous medium is usually obtained. The obtained aqueous solution containing a fluoropolymer can be directly used for various purposes, or the fluoropolymer obtained by separation from the aqueous solution can be used for various purposes. 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 precipitation, washing, and drying of the fluoropolymer in the aqueous solution.

[0371] The fluoropolymer or aqueous solution obtained by polymerizing monomer (I) contains fractions with a molecular weight of 3000 or less, fractions with a molecular weight of 2000 or less, fractions with a molecular weight of 1500 or less, fractions with a molecular weight of 1000 or less, dimers and trimers of monomer (I), etc. In order to remove these components, the fluoropolymer or aqueous solution obtained by polymerizing monomer (I) can be post-treated.

[0372] For example, in the manufacturing method of the present disclosure, after the polymerization of monomer (I) is completed, a composition containing an aqueous medium and a fluoropolymer can be recovered, and the obtained composition can be treated by at least one means selected from the group consisting of ultrafiltration, microfiltration, dialysis membrane treatment, liquid separation, and reprecipitation.

[0373] In the case where the polymerization of monomer (I) is carried out in the absence of an aqueous medium, a fluoropolymer or a composition containing a fluoropolymer, etc. is obtained after the polymerization is completed. Therefore, the fluoropolymer or the composition can be mixed with the aqueous medium, and the obtained composition containing the aqueous medium and the fluoropolymer can be treated by at least one means selected from the group consisting of ultrafiltration, microfiltration, dialysis membrane treatment, liquid separation, and reprecipitation.

[0374] In the composition obtained by polymerizing monomer (I), as the fluoropolymer of monomer (I), generally, dimers and trimers in a total amount greater than 1.0% by mass are contained relative to the mass of the fluoropolymer of monomer (I). As the content of dimers and trimers in the fluoropolymer of monomer (I), for example, it can be 2.0% by mass or more, or can be 3.0% by mass or more, and can be 30.0% by mass or less, or can be 20.0% by mass or less relative to the fluoropolymer of monomer (I). The content of dimers and trimers in the composition can be determined as follows: perform gel permeation chromatography (GPC) analysis of the composition, calculate the ratio (area percentage) of the total peak area of each peak in the chromatogram obtained by GPC analysis, and the total peak area of dimers and trimers, thereby determining the content.

[0375] Next, it is preferable to recover the obtained composition containing an aqueous medium and a fluoropolymer, and the obtained composition is treated by at least one means selected from the group consisting of ultrafiltration, microfiltration, dialysis membrane treatment, liquid separation, and reprecipitation. By this treatment, dimers and trimers of monomer (I) contained in the composition obtained by polymerizing monomer (I) can be removed from the composition. As the treatment means, it is more preferable to select at least one means from the group consisting of ultrafiltration, microfiltration, liquid separation, and reprecipitation, and further preferably select at least one means from the group consisting of ultrafiltration and liquid separation, and particularly preferably ultrafiltration.

[0376] The polymerization of monomer (I) generates dimers and trimers of monomer (I), and as a result, the dimers and trimers of monomer (I) are contained in the fluoropolymer. The generation mechanism of the dimers and trimers of monomer (I) is not necessarily clear, and it is speculated that, especially in the monomers present in the polymerization system, through the polymerization reaction in the polymerization system where monomer (I) accounts for the majority, the dimerization and trimerization of monomer (I) occur at a non-negligible frequency.

[0377] When removing the dimers and trimers, usually, the unreacted monomer (I) is also removed from the composition at the same time. In addition, by appropriately selecting the post-treatment means, it is also possible to remove the fraction with a molecular weight of 3000 or less, the fraction with a molecular weight of 2000 or less, the fraction with a molecular weight of 1500 or less, and the fraction with a molecular weight of 1000 or less.

[0378] The composition obtained by the polymerization of monomer (I) can be the composition that has completed polymerization during the polymerization, or a substance obtained by diluting or concentrating the composition that has completed polymerization during the polymerization, or a substance that has been subjected to dispersion stabilization treatment, etc. In order to smoothly perform ultrafiltration, microfiltration, or dialysis membrane treatment, it is also preferable to adjust the viscosity of the composition through these treatments.

[0379] The content of the fluoropolymer of monomer (I) in the composition is not particularly limited, and for example, it can be 0.1 to 40.0% by mass. From the aspect of the removal efficiency of dimers and trimers, the content of the fluoropolymer in the composition is preferably 30.0% by mass or less, more preferably 25.0% by mass or less, further preferably 20.0% by mass or less, particularly preferably 10.0% by mass or less, and preferably 0.5% by mass or more, more preferably 1.0% by mass or more, further preferably 1.2% by mass or more, particularly preferably 1.5% by mass or more. The content of the fluoropolymer in the composition can be adjusted, for example, by the method of adding water to the composition obtained by the polymerization of monomer (I), the method of concentrating the composition obtained by the polymerization of monomer (I), etc.

[0380] As the pH of the composition, it is preferably 0 to 11, more preferably 0.1 to 8.0, further preferably 0.2 to 7.0. The pH of the composition can be adjusted by adding a pH regulator to the composition obtained by the polymerization of monomer (I). As the pH regulator, it can be an acid or a base, and examples thereof include phosphates, sodium hydroxide, potassium hydroxide, ammonia water, etc.

[0381] In the case of ultrafiltration, microfiltration or dialysis membrane treatment, for the reason of smoothly carrying out these treatments, the viscosity of the composition is preferably 25 mPa·s or less. The viscosity of the composition can be adjusted, for example, by a method of adjusting the weight average molecular weight and number average molecular weight of the fluoropolymer, a method of adjusting the concentration of the fluoropolymer in the composition, a method of adjusting the temperature of the composition, and the like.

[0382] The above ultrafiltration or microfiltration can be in a cross-flow mode or a dead-end mode, without limitation. From the aspect of reducing membrane fouling, the cross-flow mode is preferred.

[0383] The above ultrafiltration can be carried out using an ultrafiltration membrane. Ultrafiltration can be carried out, for example, using an ultrafiltration device having an ultrafiltration membrane, and centrifugal ultrafiltration, batch ultrafiltration, circulation ultrafiltration, etc. can be adopted.

[0384] The cut-off molecular weight of the above ultrafiltration membrane is usually about 0.1×10 4 ~30×10 4 Da. For the reason of being able to inhibit membrane fouling and effectively reducing dimers and trimers, the cut-off molecular weight of the above ultrafiltration membrane is preferably 0.3×10 4 Da or more. The above cut-off molecular weight is more preferably 0.5×10 4 Da or more, particularly preferably 0.6×10 4 Da or more, and most preferably 0.8×10 4 Da or more. The above cut-off molecular weight can be 1.0×10 4 Da or more. In addition, from the aspect of the removal efficiency of dimers and trimers, the above cut-off molecular weight is preferably 20×10 4 Da or less, and more preferably 10×10 4 Da or less.

[0385] Regarding the cut-off molecular weight of the above ultrafiltration membrane, for example, polystyrene with a known weight average molecular weight can be passed through the membrane, and the molecular weight that can block 90% is taken as the cut-off molecular weight. The quantification of polystyrene can be carried out using gel permeation chromatography.

[0386] As the shape of the above ultrafiltration membrane, known shapes in the art can be cited, but there is no limitation. For example, hollow fiber type, flat membrane type, spiral type, tubular type, etc. can be cited. From the aspect of inhibiting fouling, the hollow fiber type is preferred.

[0387] The inner diameter of the hollow fiber type ultrafiltration membrane is not limited. For example, it can be 0.1 to 2 mm. Preferably it is 0.8 to 1.4 mm.

[0388] The length of the hollow fiber type ultrafiltration membrane is not limited. For example, it can be 0.05 to 3 m. Preferably it is 0.05 to 2 m.

[0389] The material of the ultrafiltration membrane is not particularly limited, and 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, polytetrafluoroethylene, metals such as stainless steel, or inorganic materials such as ceramics.

[0390] The material of the ultrafiltration membrane is preferably an organic material, more preferably chlorinated polyethylene, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, polyacrylonitrile, polysulfone or polyethersulfone, and further preferably polyacrylonitrile, polysulfone or polyvinylidene fluoride.

[0391] Specific examples of the above ultrafiltration membrane include the G-5 type, G-10 type, G-20 type, G-50 type, PW type, and HWS UF type of DESAL Company; the 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 of KOCH Company; the SPE1, SPE3, SPE5, SPE10, SPE30, SPV5, SPV50, and SOW30 of Synder Company; the Microza (registered trademark) UF series manufactured by Asahi Kasei Corporation; the NTR7410 manufactured by Nitto Denko Corporation, etc.

[0392] From the aspect of the removal efficiency of dimers and trimers, the above ultrafiltration is preferably carried out under a pressure of 0.01 MPa or more. More preferably, it is 0.03 MPa or more, and further preferably 0.05 MPa or more. In addition, from the aspect of pressure resistance, the above pressure is preferably 0.5 MPa or less, more preferably 0.25 MPa or less, and further preferably 0.2 MPa or less.

[0393] From the aspect of the removal efficiency of dimers and trimers, the above 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. In addition, it 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.

[0394] The above microfiltration can use a microfiltration membrane. The microfiltration membrane usually has an average pore diameter of 0.05 to 1.0 μm.

[0395] For the reason that the removal efficiency of dimers and trimers can be effectively obtained, the average pore diameter of the above-mentioned microfiltration membrane is preferably 0.1 μm or more. More preferably, it is 0.075 μm or more, and still more preferably 0.1 μm or more. In addition, the average pore diameter is preferably 1.00 μm or less. More preferably, the average pore diameter is 0.50 μm or less, and still more preferably 0.25 μm or less.

[0396] The average pore diameter of the above-mentioned microfiltration membrane can be measured according to ASTM F316-03 (bubble point method).

[0397] As the shape of the above-mentioned microfiltration membrane, known shapes can be cited without limitation. For example, a hollow fiber type, a flat membrane type, a spiral type, a tubular type, etc. can be cited. From the aspect of suppressing clogging, the hollow fiber type is preferred.

[0398] The inner diameter of the hollow fiber type microfiltration membrane is not limited. For example, it can be 0.1 to 2 mm. Preferably, it is 0.8 to 1.4 mm.

[0399] The length of the hollow fiber type microfiltration membrane is not limited. For example, it can be 0.05 to 3 m. Preferably, it is 0.05 to 2 m.

[0400] As the material of the above-mentioned microfiltration membrane, for example, a cellulose-based material, an aromatic polyamide, polyvinyl alcohol, polysulfone, polyethersulfone, polyvinylidene fluoride, polyethylene, polyacrylonitrile, polypropylene, polycarbonate, polytetrafluoroethylene, ceramics, metals, etc. can be cited. Among them, an aromatic polyamide, polyvinyl alcohol, polysulfone, polyvinylidene fluoride, polyethylene, polyacrylonitrile, polypropylene, polycarbonate or polytetrafluoroethylene is preferred, and polyacrylonitrile or polyvinylidene fluoride is particularly preferred.

[0401] As the microfiltration membrane, specifically, 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.; Trefil manufactured by Toray Industries, Inc.; NADIR MP005 and NADIR MV020 manufactured by Microdyn-Nadir GmbH; X-flow manufactured by Norit NV, etc. can be cited.

[0402] From the aspect of the removal efficiency of dimers and trimers, the above-mentioned microfiltration is preferably carried out at a pressure of 0.01 MPa or more. More preferably, it is 0.03 MPa or more, and still more preferably 0.05 MPa or more. In addition, from the aspect of pressure resistance, the above-mentioned pressure is preferably 0.5 MPa or less, more preferably 0.25 MPa or less, and still more preferably 0.2 MPa or less.

[0403] From the aspect of the removal efficiency of 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. In addition, it 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.

[0404] The above-mentioned dialysis membrane treatment is carried out using a dialysis membrane. The dialysis membrane usually has a cut-off molecular weight of 0.05×10 4 ~100×10 4 Da.

[0405] For the reason of being able to inhibit membrane fouling and effectively remove dimers and trimers, the cut-off molecular weight of the above-mentioned dialysis membrane is preferably 0.3×10 4 Da or more. The cut-off molecular weight is more preferably 0.5×10 4 Da or more, further preferably 0.6×10 4 Da or more, and still more preferably 0.8×10 4 Da or more. The cut-off molecular weight can be 1.0×10 4 Da or more.

[0406] In addition, from the aspect of the removal efficiency of dimers and trimers, the cut-off molecular weight is preferably 20×10 4 Da or less, more preferably 10×10 4 Da or less.

[0407] The cut-off molecular weight of the above-mentioned dialysis membrane can be measured, for example, by the same method as that for an ultrafiltration membrane.

[0408] The material of the above-mentioned dialysis membrane is not particularly limited, and examples thereof include cellulose, polyacrylonitrile, polymethyl methacrylate, ethylene-vinyl alcohol copolymer, polysulfone, polyamide, polyester-based polymer alloy, etc.

[0409] Specifically, as the dialysis membrane, examples include Spectra / Por (registered trademark) Float-A-Lyzer, Tube-A-Lyzer, Dialysis tubing, 6Dialysis tubing, 7Dialysis tubing, etc. manufactured by Spectrum Laboratories.

[0410] The above ultrafiltration, microfiltration or dialysis membrane treatment is preferably carried out at a temperature above 10°C. More preferably above 15°C, further preferably above 20°C, and particularly preferably above 30°C. By setting the temperature within the above range, dimers and trimers can be effectively reduced. The above temperature is preferably 90°C or below, more preferably 80°C or below, further preferably 70°C or below, and particularly preferably 60°C or below.

[0411] Regarding ultrafiltration, microfiltration or dialysis membrane treatment, it can be carried out while adding water to the composition or while adjusting the pH of the composition. Water can be added to the composition intermittently or continuously.

[0412] The end point of ultrafiltration, microfiltration or dialysis membrane treatment can be appropriately determined without limitation. In addition, in the above ultrafiltration, microfiltration or dialysis membrane treatment, in order to improve the durability of the filter membrane, backwashing can be carried out once with water based on a filtration time of 1 to 24 hours.

[0413] Liquid separation can be carried out, for example, as follows: an organic solvent is added to the composition to separate it into two phases, an aqueous phase and an organic solvent phase, and the aqueous phase is recovered, thereby carrying out liquid separation.

[0414] Reprecipitation can be carried out, for example, as follows: the composition is dropped into a poor solvent to precipitate the fluoropolymer, the precipitated fluoropolymer is recovered, the recovered fluoropolymer is dissolved in a good solvent, the resulting solution is dropped into the poor solvent to precipitate the fluoropolymer again, and the precipitated fluoropolymer is recovered, thereby carrying out reprecipitation.

[0415] The composition of the fluoropolymer containing monomer (I) is post-treated by the above means, and usually an aqueous solution of a fluoropolymer substantially free of dimers and trimers or an aqueous solution of a fluoropolymer with a reduced content of fractions having a molecular weight of 3000 or less is obtained thereby. The aqueous solution containing the fluoropolymer obtained by treating the composition can be directly used for various purposes, or the fluoropolymer obtained by separating from the aqueous solution can be used for various purposes. 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 precipitation, washing, and drying of the fluoropolymer in the aqueous solution.

[0416] A fluoropolymer or an aqueous solution containing a fluoropolymer and an aqueous medium is obtained by the manufacturing method of the present disclosure described above.

[0417] The embodiments have been described above, but it can be understood that various changes in form and details can be made without departing from the spirit and scope of the claims.

[0418] Examples

[0419] Next, examples are given to illustrate the embodiments of the present disclosure, but the present disclosure is not limited to these examples.

[0420] The respective numerical values in the examples were measured by the following methods.

[0421] (Oxygen concentration in the reactor)

[0422] For the gas discharged from the exhaust pipe line of the reactor under N2 flow, a low-concentration oxygen analyzer (trade name "PS-820-L", manufactured by Iijima Electronic Industry Co., Ltd.) was used for measurement and analysis, and the oxygen concentration during the reaction was thereby obtained.

[0423] (Concentration of fluoropolymer in the aqueous solution (solid component concentration))

[0424] Approximately 1 g of the aqueous solution containing the fluoropolymer was dried in a vacuum dryer under the conditions of 60 °C for 60 minutes, the mass of the heating residue was measured, and the value representing the ratio of the mass of the heating residue to the mass of the aqueous solution (1 g) as a percentage was adopted.

[0425] (Method for measuring weight-average molecular weight (Mw), number-average molecular weight (Mn), and content of the fraction with a molecular weight of 3000 or less)

[0426] Regarding the Mw and Mn of the fluoropolymer, by gel permeation chromatography (GPC), using 1260 Infinity II manufactured by Agilent Technologies, a column (1 root of TSKgel G3000PW XL ) manufactured by Tosoh Corporation was used, and a mixed solvent of tris(hydroxymethyl)aminomethane buffer and acetonitrile (tris(hydroxymethyl)aminomethane buffer:acetonitrile = 8:2 (v / v)) as the solvent was passed through at a flow rate of 0.5 ml / min for measurement, and the molecular weights were calculated using monodisperse polyoxyethylene (PEO) and polyethylene glycol (PEG) as standards, and thereby obtained.

[0427] (Alternation ratio)

[0428] F-NMR measurement of the fluoropolymer was carried out, and according to the total integral values of the two peaks of "OCF2 19 " from CF2=CFOCF2CF2COOH that appeared in the NMR spectrum (the peak appearing at -79 ppm to -83 ppm and the peak appearing at -83 ppm to -87 ppm), it was calculated according to the following calculation formula. * Alternation ratio (%) ≥ (b×2) / (a + b)×100

[0429]

[0430] ​A: Total integrated value of peaks in the region of -79 ppm to -83 ppm

[0431] B: Total integrated value of peaks in the region of -83 ppm to -87 ppm

[0432] The calculated alternation ratio is the proportion of the polymer units adjacent to the VdF-based polymer units in the CF2=CFOCF2CF2COOH-based polymer units in the fluoropolymer.

[0433] Based on VdF (C * H2=CF2), the carbon atom (C * ) in the polymer unit relative to the carbon atom (C * ) in the polymer unit based on CF2=C * FOCF2CF2COOH is obtained by the following calculation formula.

[0434] Ratio (%) = (b × 2) / (a + b) × 100

[0435] Based on VdF (C * H2=CF2), carbon atoms other than the carbon atom (C * ) in the polymer unit (carbon atoms (C ** F2=C ** ) in the polymer unit based on FOCF2CF2COOH and carbon atoms (C ** ) in the polymer unit based on VdF (CH2=C ** F2)) relative to the carbon atom (C ** ) in the polymer unit based on CF2=C * FOCF2CF2COOH is obtained by the following calculation formula. * ) is obtained by the following calculation formula.

[0436] Ratio (%) = (a - b) / (a + b) × 100

[0437] (Method for determining the content of dimers and trimers of monomers in fluoropolymers)

[0438] (1) Extraction from aqueous solution

[0439] Determine the solid content of the aqueous solution of the fluoropolymer, and weigh an amount of the aqueous solution equivalent to 0.2 g of the solid content of the fluoropolymer. Then combine it with the water contained in the aqueous solution, and add water and methanol in such a way that the volume ratio of water to methanol is 50 / 50 (volume %), to obtain a mixed solution containing the fluoropolymer and water and methanol. Then, filter the obtained mixed solution using an ultrafiltration disc (cut-off molecular weight 3000 Da), and recover the recovered solution containing the fluoropolymer.

[0440] The recovered liquid was analyzed using a liquid chromatography mass spectrometer (Waters, LC-MS ACQUITY UPLC / TQD) to obtain the chromatogram of the recovered liquid.

[0441] Regarding the contents of the dimers and trimers of the monomers contained in the recovered liquid, the integral values of the peaks of the dimers and trimers of the monomers appearing in the chromatogram of the recovered liquid were converted into the contents of the dimers and trimers of the monomers by using the calibration curves of the monomers as analogs, and thus obtained.

[0442] (2) Calibration curve of monomer

[0443] Five levels of methanol standard solutions of monomers with known contents of 1 ng / mL to 100 ng / mL were prepared and measured using a liquid chromatography mass spectrometer (Waters, LC-MS ACQUITY UPLC / TQD). The relationship between the content of each monomer and the integral value of the peak corresponding to that content was plotted to prepare the calibration curve (first approximation) of each monomer. Then, using the calibration curves (first approximation) of each monomer, the calibration curves of the dimers and trimers of each monomer were prepared.

[0444] Composition of the measuring device and LC-MS measurement conditions

[0445] [Table 1]

[0446]

[0447] The limit of quantitation in the composition of the measuring device was 1 ng / mL.

[0448] <Example 1>

[0449] 10 g of CF2=CFOCF2CF2COOH, 20 g of water, and ammonium persulfate (APS) in an amount equivalent to 0.5 mol% of the amount of CF2=CFOCF2CF2COOH were added to the reactor, and the mixture was stirred at 52 °C under a nitrogen flow. After 24 hours from the addition of APS, APS in an amount equivalent to 1.0 mol% was added, and after 48 hours, APS in an amount equivalent to 1.5 mol% was further added, and the mixture was stirred at 52 °C for a total of 72 hours. The oxygen concentration in the reactor varied within the range of 15 volume ppm to 40 volume ppm.

[0450] Water was added to the obtained aqueous solution containing the fluoropolymer to adjust the concentration of the fluoropolymer to 2.0 mass%. After that, it was brought into contact with an ultrafiltration membrane (molecular weight cut-off: 6000 Da, made of polysulfone) at a water pressure of 0.1 MPa at 25°C, and ultrafiltration was carried out. Ultrafiltration was continued while appropriately injecting water until a filtrate of 7 times the amount of water relative to the aqueous solution was finally eluted, obtaining an aqueous solution of the fluoropolymer. The concentration of the aqueous solution obtained by carrying out ultrafiltration was 2.1 mass%.

[0451] The aqueous solution obtained by carrying out ultrafiltration was analyzed. The weight-average molecular weight (Mw) of the obtained fluoropolymer was 1.7×10 4 and the number-average molecular weight (Mn) was 1.1×10 4 . The contents of the dimer and trimer in the aqueous solution obtained by carrying out ultrafiltration were 0.1 mass% or less relative to the fluoropolymer. The content of the fraction with a molecular weight of 3000 or less in the aqueous solution obtained by carrying out ultrafiltration was 0.1 mass% or less.

[0452] <Example 2>

[0453] 10 g of CF2=CFOCF2CF2COOH, 20 g of water, and ammonium persulfate (APS) in an amount equivalent to 2.0 mol% of the amount of CF2=CFOCF2CF2COOH were added to a reactor, and the mixture was stirred at 50°C for 63 hours under a flow of N2. The oxygen concentration in the reactor ranged from 17 volume ppm to 33 volume ppm.

[0454] Water was added to the obtained aqueous solution containing the fluoropolymer to adjust the concentration of the fluoropolymer to 2.0 mass%. After that, it was brought into contact with an ultrafiltration membrane (molecular weight cut-off: 6000 Da, made of polysulfone) at a water pressure of 0.1 MPa at 25°C, and ultrafiltration was carried out. Ultrafiltration was continued while appropriately injecting water until a filtrate of 7 times the amount of water relative to the aqueous solution was finally eluted, obtaining an aqueous solution of the fluoropolymer. The concentration of the aqueous solution obtained by carrying out ultrafiltration was 2.1 mass%.

[0455] The aqueous solution obtained by carrying out ultrafiltration was analyzed. The weight-average molecular weight (Mw) of the obtained fluoropolymer was 1.9×10 4 and the number-average molecular weight (Mn) was 1.3×10 4 . The contents of the dimer and trimer in the aqueous solution obtained by carrying out ultrafiltration were 0.1 mass% or less relative to the fluoropolymer. The content of the fraction with a molecular weight of 3000 or less in the aqueous solution obtained by carrying out ultrafiltration was 0.1 mass% or less.

[0456] <Example 3>

[0457] Polymerization was carried out in the same manner as in Example 1 except that the reaction temperature was changed to 40 °C.

[0458] Ultrafiltration was carried out on the obtained aqueous solution containing the fluoropolymer in the same manner as in Example 1. The concentration of the aqueous solution obtained by ultrafiltration was 2.1% by mass.

[0459] The aqueous solution obtained by ultrafiltration was analyzed. The weight-average molecular weight (Mw) of the obtained fluoropolymer was 2.7×10 4 , and the number-average molecular weight (Mn) was 1.4×10 4 . The contents of the dimer and trimer in the aqueous solution obtained by ultrafiltration were 0.1% by mass or less relative to the fluoropolymer. The content of the fraction having a molecular weight of 3000 or less in the aqueous solution obtained by ultrafiltration was 0.1% by mass or less.

[0460] <Example 4>

[0461] 10 g of CF2=CFOCF2CF2COOH, 20 g of water, and ammonium persulfate (APS) in an amount equivalent to 2.0 mol% of the amount of CF2=CFOCF2CF2COOH were added to the reactor, and the mixture was stirred at 40 °C for 72 hours under a flow of N2. The oxygen concentration in the reactor ranged from 15 to 35 volume ppm.

[0462] Water was added to the obtained aqueous solution containing the fluoropolymer, and after adjusting the concentration of the fluoropolymer to 2.0% by mass, it was brought into contact with an ultrafiltration membrane (cut-off molecular weight 6000 Da, made of polysulfone) at a water pressure of 0.1 MPa at 25 °C, and ultrafiltration was carried out. Ultrafiltration was continued while appropriately injecting water until a filtrate of 7 times the amount of the aqueous solution was finally eluted, and an aqueous solution of the fluoropolymer was obtained. The concentration of the aqueous solution obtained by ultrafiltration was 2.1% by mass.

[0463] The aqueous solution obtained by ultrafiltration was analyzed. The weight-average molecular weight (Mw) of the obtained fluoropolymer was 2.9×10 4 , and the number-average molecular weight (Mn) was 1.5×10 4 . The contents of the dimer and trimer in the aqueous solution obtained by ultrafiltration were 0.1% by mass or less relative to the fluoropolymer. The content of the fraction having a molecular weight of 3000 or less in the aqueous solution obtained by ultrafiltration was 0.1% by mass or less.

[0464] <Example 5>

[0465] Polymerization was carried out in the same manner as in Example 3 except that the amount of water was changed to 10 g.

[0466] For the obtained aqueous solution containing a fluoropolymer, ultrafiltration was carried out in the same manner as in Example 1. The aqueous solution obtained by carrying out ultrafiltration was analyzed. The concentration of the aqueous solution obtained by carrying out ultrafiltration was 2.0% by mass.

[0467] The weight-average molecular weight (Mw) of the obtained fluoropolymer was 4.3×10 4 and the number-average molecular weight (Mn) was 1.9×10 4 . The contents of dimers and trimers in the aqueous solution obtained by carrying out ultrafiltration were 0.1% by mass or less relative to the fluoropolymer. The content of the fraction having a molecular weight of 3000 or less in the aqueous solution obtained by carrying out ultrafiltration was 0.1% by mass or less.

[0468] <Example 6>

[0469] 30 g of CF2=CFOCF2CF(CF3)OCF2CF2COOH, 60 g of water, ammonium persulfate (APS) in an amount corresponding to 2.0 mol% of the amount of CF2=CFOCF2CF(CF3)OCF2CF2COOH, and NH3 in an amount corresponding to 0.5 equivalent of the amount of CF2=CFOCF2CF(CF3)OCF2CF2COOH were added to a reactor, and the mixture was stirred at 52°C for 72 hours under a flow of N2. The oxygen concentration in the reactor changed within the range of 20 to 50 volume ppm.

[0470] Water and NH3 in an amount corresponding to 0.4 equivalent of the amount of CF2=CFOCF2CF(CF3)OCF2CF2COOH used in the polymerization were added to the obtained aqueous solution containing a fluoropolymer. After adjusting the concentration of the fluoropolymer to 3.0% by mass, the solution was brought into contact with an ultrafiltration membrane (cutoff molecular weight: 6000 Da, made of polysulfone) at a water pressure of 0.1 MPa at 25°C, and ultrafiltration was carried out. Ultrafiltration was continued while appropriately adding water until a filtrate four times the amount of the aqueous solution was finally eluted, obtaining an aqueous solution of a fluoropolymer. The concentration of the aqueous solution obtained by carrying out ultrafiltration was 3.1% by mass.

[0471] The aqueous solution obtained by carrying out ultrafiltration was analyzed. The weight-average molecular weight (Mw) of the obtained fluoropolymer was 1.4×10 4 and the number-average molecular weight (Mn) was 0.9×10 4 . The contents of dimers and trimers in the aqueous solution obtained by carrying out ultrafiltration were 0.1% by mass or less relative to the fluoropolymer. The content of the fraction having a molecular weight of 3000 or less in the aqueous solution obtained by carrying out ultrafiltration was 0.1% by mass or less.

[0472] <Comparative Example 1>

[0473] 10 g of CF2=CFOCF2CF2COOH, 20 g of water, and APS in an amount equivalent to 3.0 mol% of the amount of CF2=CFOCF2CF2COOH were added to a reactor, and stirring was carried out at 80 °C for 24 hours under a nitrogen flow. The oxygen concentration in the reactor changed within the range of 25 to 51 volume ppm.

[0474] For the obtained aqueous solution containing a fluoropolymer, ultrafiltration was carried out in the same manner as in Example 1. The concentration of the aqueous solution obtained by ultrafiltration was 2.0 mass%.

[0475] The aqueous solution obtained by ultrafiltration was analyzed. The weight-average molecular weight (Mw) of the obtained fluoropolymer was 0.7×10 4 and the number-average molecular weight (Mn) was 0.6×10 4 . The contents of dimers and trimers in the aqueous solution obtained by ultrafiltration were 0.1 mass% or less relative to the fluoropolymer. The content of the fraction having a molecular weight of 3000 or less in the aqueous solution obtained by ultrafiltration was 0.1 mass% or less.

[0476] <Example 7>

[0477] 6 g of CF2=CFOCF2CF2COOH and a solution of Peroyl IPP (registered trademark, manufactured by NOF Corporation) in an amount equivalent to 2 mol% of the amount of CF2=CFOCF2CF2COOH in terms of solid content were added to a reactor, and stirring was carried out at 45 °C for 72 hours under a nitrogen flow. The oxygen concentration in the reactor changed within the range of 50 to 105 volume ppm.

[0478] Water was added to the obtained fluoropolymer, and after adjusting the concentration of the fluoropolymer to 30 mass%, purification was carried out using a dialysis membrane (cutoff molecular weight 3500 Da, made of regenerated cellulose) to obtain an aqueous solution of the fluoropolymer. The concentration of the aqueous solution obtained by dialysis was 3.0 mass%.

[0479] The aqueous solution obtained by dialysis was analyzed. The weight-average molecular weight (Mw) of the obtained fluoropolymer was 2.4×10 4 and the number-average molecular weight (Mn) was 1.5×10 4 . The contents of dimers and trimers in the aqueous solution obtained by dialysis were 0.1 mass% or less relative to the fluoropolymer. The content of the fraction having a molecular weight of 3000 or less in the aqueous solution obtained by dialysis was 0.1 mass% or less.

[0480] <Example 8>

[0481] 1.5 g of CF₂=CFOCF₂CF₂COOH, 3.5 g of water, iron(III) sulfate heptahydrate in an amount equivalent to 2.0 mol% relative to the amount of CF₂=CFOCF₂CF₂COOH, and sodium sulfite in an amount equivalent to 6.0 mol% were added to a reactor. An aqueous solution of ammonium persulfate (APS) in an amount equivalent to 2.0 mol% relative to the amount of CF₂=CFOCF₂CF₂COOH was added thereto, and the mixture was stirred at room temperature for 4.5 days under a nitrogen flow. The oxygen concentration in the reactor changed within the range of 32 to 55 volume ppm.

[0482] The obtained aqueous solution containing the fluoropolymer was placed in a dialysis membrane (cutoff molecular weight 3500 Da, made of cellulose), and dialysis was carried out by contacting it with water at room temperature to obtain an aqueous solution of the fluoropolymer.

[0483] The aqueous solution obtained by dialysis was analyzed, and as a result, the weight-average molecular weight (Mw) of the obtained fluoropolymer was 4.3×10 4 and the number-average molecular weight (Mn) was 3.1×10 4 . The contents of the dimer and trimer in the aqueous solution obtained by dialysis were 0.1 mass% or less relative to the fluoropolymer. The content of the fraction having a molecular weight of 3000 or less in the aqueous solution obtained by dialysis was 0.1 mass% or less.

[0484] <Example 9>

[0485] 1.21 g of CF₂=CFOCF₂CF₂COOH, 8.5 g of water, and ammonium persulfate (APS) in an amount equivalent to 1.5 mol% relative to the amount of CF₂=CFOCF₂CF₂COOH were added to a reactor. After nitrogen replacement and degassing, 1.21 g of VdF was introduced, and the mixture was stirred at 60 °C for 4 hours under a closed condition. As the reaction proceeded, the internal pressure of the reactor decreased from 0.30 MPa to 0.25 MPa.

[0486] The obtained aqueous solution containing the fluoropolymer was placed in a dialysis membrane (cutoff molecular weight 3500 Da, made of cellulose), and dialysis was carried out by contacting it with water at room temperature to obtain an aqueous solution of the fluoropolymer. The concentration of the aqueous solution obtained by purification using the dialysis membrane was 1.72 mass%.

[0487] The aqueous solution obtained by dialysis was analyzed by NMR to investigate the polymer composition. As a result, the molar ratio of the polymerization unit based on CF₂=CFOCF₂CF₂COOH to the polymerization unit based on VdF contained in the fluoropolymer was 1.0 / 0.7. In addition, the alternation rate of the polymerization unit based on CF₂=CFOCF₂CF₂COOH to the polymerization unit based on VdF in the fluoropolymer was 62% or more.

[0488] The weight-average molecular weight (Mw) of the resulting fluoropolymer was 11.9×10 4 and the number-average molecular weight (Mn) was 4.5×10 4 . The contents of the dimer and trimer in the aqueous solution obtained by dialysis were 0.1% by mass or less relative to the fluoropolymer. The content of the fraction having a molecular weight of 3000 or less in the aqueous solution obtained by dialysis was 0.1% by mass or less.

[0489] <Example 10>

[0490] 2.42 g of CF2=CFOCF2CF2COOH, 3.16 g of CF2=CFOCF2CF2SO3Na, 11 g of water, and ammonium persulfate (APS) in an amount equivalent to 1.5 mol% based on the total amount of CF2=CFOCF2CF2COOH and CF2=CFOCF2CF2SO3Na were added to the reactor, and the mixture was stirred at 40°C for 21 hours under a nitrogen flow, and further stirred at room temperature for 91 hours. The oxygen concentration in the reactor changed within the range of 66 to 98 volume ppm.

[0491] The aqueous solution containing the fluoropolymer obtained was placed in a dialysis membrane (cutoff molecular weight: 3500 Da, made of cellulose), and dialysis was carried out by bringing it into contact with water at room temperature to obtain an aqueous solution of the fluoropolymer. The concentration of the aqueous solution obtained by purification with the dialysis membrane was 1.1% by mass.

[0492] The aqueous solution obtained by dialysis was analyzed by NMR to investigate the polymer composition. As a result, the molar ratio of the polymerization unit based on CF2=CFOCF2CF2COOH to the polymerization unit based on CF2=CFOCF2CF2SO3Na contained in the polymer was 1.0 / 0.8.

[0493] The weight-average molecular weight (Mw) of the resulting fluoropolymer was 2.0×10 4 and the number-average molecular weight (Mn) was 1.3×10 4 . The contents of the dimer and trimer in the aqueous solution obtained by dialysis were 0.1% by mass or less relative to the fluoropolymer. The content of the fraction having a molecular weight of 3000 or less in the aqueous solution obtained by dialysis was 0.1% by mass or less.

Claims

1. A fluorine-containing polymer, which is a fluorine-containing polymer of monomer (I) represented by general formula (I), wherein, Based on all the polymerized units constituting the fluorine-containing polymer, the content of polymerized unit (I) based on monomer (I) is 80 mol% or more. The weight-average molecular weight (Mw) of the fluoropolymer is 1.4×10 4 or more, and the ion exchange capacity is 2.20 meq / g or more. General formula (I): CX2=CX-O-Rf-A In the formula, X is independently F or CF3, Rf is a fluoroalkylene group having 1 to 40 carbon atoms, or a fluoroalkylene group having an ether bond or a keto group and having 2 to 100 carbon atoms; A is -COOM, -SO3M, -OSO3M or -C(CF3)2OM, where M is -H, a metal atom, -NR 7 4. An imidazolium with or without substituents, a pyridinium with or without substituents, or a phosphonium with or without substituents, R 7 is H or an organic group.

2. The fluorine-containing polymer according to claim 1, wherein, The weight-average molecular weight (Mw) is 1.9×10 4 or more.

3. The fluoropolymer according to claim 1 or 2, wherein The molecular weight distribution (Mw / Mn) is 3.0 or less.

4. The fluoropolymer according to claim 1 or 2, wherein, Each X is F.

5. The fluoropolymer according to claim 1 or 2, wherein Rf is a fluorinated alkylene group having 1 to 5 carbon atoms, or a fluorinated alkylene group having 2 to 5 carbon atoms and having an ether bond or a ketone group.

6. The fluoropolymer according to claim 1 or 2, wherein A is -COOM.

7. The fluoropolymer according to claim 1 or 2, wherein, The fluorine-containing polymer is a copolymer of monomer (I) and a monomer represented by general formula CFR=CR2, in the formula CFR=CR2, R is independently H, F or a perfluoroalkyl group having 1 to 4 carbon atoms.

8. The fluoropolymer according to claim 1 or 2, wherein, Based on all the polymerized units constituting the fluorine-containing polymer, the content of polymerized unit (I) is 99 mol% or more.

9. The fluorine-containing polymer according to claim 1 or 2, wherein, The fluorine-containing polymer substantially does not contain dimers and trimers of monomer (I).

10. The fluoropolymer according to claim 1 or 2, wherein, Based on the fluorine-containing polymer, the content of the fraction having a molecular weight of 3000 or less is 3.7% or less.

11. An aqueous solution containing the fluorine-containing polymer according to any one of claims 1 to 10.

12. The aqueous solution according to claim 11, wherein, Based on the aqueous solution, the content of the fluorine-containing polymer is 2% by mass or more.

13. A coating composition containing the fluorine-containing polymer according to any one of claims 1 to 10, or containing the aqueous solution according to claim 11 or 12.

14. A method for producing a fluoropolymer, which is a method for producing a fluoropolymer of monomer (I) by polymerizing monomer (I) represented by the general formula (I) in an aqueous medium substantially in the absence of a fluorosurfactant, wherein, Maintain the oxygen concentration in the polymerization reaction system at 1500 volume ppm or less. General formula (I): CX2=CX-O-Rf-A In the formula, X is independently F or CF3, Rf is a fluoroalkylene group having 1 to 40 carbon atoms, or a fluoroalkylene group having an ether bond or a keto group and having 2 to 100 carbon atoms; A is -COOM, -SO3M, -OSO3M or -C(CF3)2OM, where M is -H, a metal atom, -NR 7 4. Imidazolium with or without substituents, pyridinium with or without substituents, or phosphonium with or without substituents, R 7 is H or an organic group.

15. The manufacturing method according to claim 14, wherein, Polymerize monomer (I) at a polymerization temperature of 70°C or less.

16. The manufacturing method according to claim 14 or 15, wherein, Polymerize monomer (I) in the presence of a polymerization initiator, and the polymerization initiator is a persulfate.

17. The manufacturing method according to claim 14 or 15, wherein Polymerize monomer (I) in the presence of a polymerization initiator, and the polymerization initiator is added at the start of polymerization and also during polymerization.

18. The manufacturing method according to claim 14 or 15, wherein Polymerize monomer (I) in an aqueous medium in the presence of a polymerization initiator, and the total addition amount of the polymerization initiator used in the polymerization is 0.00001% by mass to 10% by mass based on the aqueous medium.

19. The manufacturing method according to claim 14 or 15, wherein, The amount of the monomer containing monomer (I) present at the start of polymerization is 40% by mass or more based on the amount of the aqueous medium present.

20. The manufacturing method according to claim 14 or 15, wherein Based on all the polymerized units constituting the fluorine-containing polymer, the content of polymerized unit (I) in the fluorine-containing polymer is 40 mol% or more.

21. The manufacturing method according to claim 14 or 15, wherein The weight-average molecular weight (Mw) of the fluoropolymer is 1.4×10 4 or more.

22. The manufacturing method according to claim 14 or 15, wherein After polymerization, recover the composition containing the aqueous medium and the fluorine-containing polymer, and treat the composition by at least one means selected from the group consisting of ultrafiltration, microfiltration, dialysis membrane treatment, liquid separation, and reprecipitation.

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