Water treatment method and composition

Abstract

To provide a novel treatment method for removing a specific polymer from water.SOLUTION: A water treatment method comprises a removal step of removing a polymer (I) containing a polymerization unit (I) based on a monomer represented by the following general formula (I) from water containing the polymer (I): CX1X3=CX2R(-CZ1Z2-A0)m (I), wherein X1 and X3 are each independently F, Cl, H, or CF3; X2 is H, F, an alkyl group, or a fluorine-containing alkyl group; A0 is an anionic group; R is a linking group; Z1 and Z2 are each independently H, F, an alkyl group, or a fluorine-containing alkyl group; and m is an integer of 1 or more.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a method and composition for treating water.

Background Art

[0002] Wastewater generated during industrial production may contain various chemical substances used in the production process, and methods for treating the wastewater have been proposed.

[0003] For example, Patent Document 1 describes a method for treating fluorine-containing wastewater, which includes a step of adding 15 to 70 mg of aluminum ions to 1 mg of fluoride ions to the fluorine-containing wastewater, and a step of adding a flocculant.

[0004] Patent Document 2 describes a wastewater treatment apparatus for removing fluorine from sulfate-containing wastewater, which includes a mixing section for mixing the sulfate-containing wastewater and an aluminum-based inorganic flocculant, a solid-liquid separation section for solid-liquid separating the mixed liquid mixed in the mixing section, and a supply means for supplying the solid content obtained by solid-liquid separation in the solid-liquid separation section to the mixing section.

[0005] Patent Document 3 describes a method for treating fluorine-containing wastewater in which calcium is added to the fluorine-containing wastewater to solid-liquid separate fluorine in the wastewater as calcium fluoride insoluble matter, wherein calcium is added to the wastewater, a chemical agent containing a phosphate compound is added without separating the generated insoluble precipitate, and then an aluminum salt having a basicity of 20 to 80% is added.

[0006] Non-Patent Document 1 describes a method for removing fluorine from wastewater containing fluorine as a wastewater treatment apparatus, in which an aluminum-based inorganic flocculant is mixed with the wastewater to generate flocs of aluminum hydroxide (Al2(OH)3), and fluorine is adsorbed and coprecipitated by the flocs.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Non-Patent Document

[0008]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] The present disclosure provides a novel treatment method for removing a specific polymer from water.

Means for Solving the Problems

[0010] The present disclosure provides a water treatment method (hereinafter also referred to as “the first treatment method of the present disclosure”) characterized by including a removal step of removing a polymer (I) from water containing the polymer (I) including a polymerization unit (I) based on a monomer represented by the following general formula (I). CX 1 X 3 =CX 2 R(-CZ 1 Z 2 -A 0 ) m (I) (In the formula, X 1 and X 3 are each independently F, Cl, H or CF3; X 2 is H, F, an alkyl group or a fluorine-containing alkyl group; A 0 is an anionic group; R is a linking group; Z 1 and Z 2Each independently represents H, F, an alkyl group, or a fluorinated alkyl group; m is an integer of 1 or more.)

[0011] The above polymer (I) is preferably a water-soluble polymer.

[0012] The above removal step is preferably a step of performing at least one of filtration, adsorption, and aggregation on the water containing the polymer (I).

[0013] The above removal step is preferably a step of performing aggregation on the water containing the polymer (I).

[0014] The above removal step is preferably a step of adding an inorganic flocculant to the water containing the polymer (I).

[0015] The above inorganic flocculant is preferably at least one metal salt selected from the group consisting of aluminum salts, iron salts, calcium salts, and silicate minerals containing a divalent or higher metal element and silicon.

[0016] The above inorganic flocculant is preferably at least one aluminum salt selected from the group consisting of aluminum sulfate and polyaluminum chloride.

[0017] The above removal step is preferably a step of adding a polymer flocculant to the water containing the polymer (I).

[0018] The above polymer flocculant is preferably an anionic polymer flocculant.

[0019] The above removal step is preferably a step of adding an inorganic flocculant to the water containing the polymer (I) and then adding a polymer flocculant.

[0020] The water containing the polymer (I) is preferably water that has undergone a polymerization step of a fluoropolymer.

[0021] The present disclosure also provides a composition comprising a polymer (I) containing a polymerizable unit (I) based on a monomer represented by the following general formula (I), water, and a fluorine-containing polymer (excluding the polymer (I)), wherein the content of the polymer (I) is 250 ppm or less. CX 1 X 3 =CX 2 R(-CZ 1 Z 2 -A 0 ) m (I) (In the formula, X 1 and X 3 are each independently F, Cl, H or CF3; X 2 is H, F, an alkyl group or a fluorine-containing alkyl group; A 0 is an anionic group; R is a linking group; Z 1 and Z 2 are each independently H, F, an alkyl group or a fluorine-containing alkyl group; and m is an integer of 1 or more.)

[0022] The polymer (I) may be a water-soluble polymer in which the proportion of hydrogen atoms bonded to carbon atoms substituted by fluorine atoms is 50% or more. The polymer (I) may be a polymer in which the proportion of hydrogen atoms bonded to carbon atoms substituted by fluorine atoms is 50% or more, contains an ionic group, and has an ion exchange rate of 53 or less.

[0023] The present disclosure also provides a composition comprising a water-soluble polymer in which the proportion of hydrogen atoms bonded to carbon atoms substituted by fluorine atoms is 50% or more, water, and a fluorine-containing polymer (excluding the water-soluble polymer), wherein the content of the water-soluble polymer is 250 ppm or less.

[0024] The present disclosure also provides a composition comprising a polymer in which the proportion of hydrogen atoms bonded to carbon atoms being substituted with fluorine atoms is 50% or more, containing an ionic group and having an ion exchange rate of 53 or less, water, and a fluorine-containing polymer (excluding the polymer), wherein the content of the polymer is 250 ppm or less.

[0025] The fluorine-containing polymer preferably has an ion exchange rate higher than 53. The fluorine-containing polymer is preferably polytetrafluoroethylene. In the composition of the present disclosure, the content of the fluorine-containing polymer is preferably 1 to 5000 ppm. The composition of the present disclosure preferably further contains a divalent or higher metal ion. In the composition of the present disclosure, the content of the divalent or higher metal ion is preferably 0.05 to 1000 mg / L or more.

[0026] The present disclosure further provides a composition comprising a polymer (I) containing a polymerization unit (I) based on a monomer represented by the following general formula (I), water, and a divalent or higher metal ion, wherein the content of the polymer (I) is 250 ppm or less. CX 1 X 3 =CX 2 R(-CZ 1 Z 2 -A 0 ) m (I) (In the formula, X 1 and X 3 are each independently F, Cl, H, or CF3; X 2 is H, F, an alkyl group, or a fluorine-containing alkyl group; A 0 is an anionic group; R is a linking group; Z 1 and Z 2 are each independently H, F, an alkyl group, or a fluorine-containing alkyl group; and m is an integer of 1 or more.)

[0027] The present disclosure also provides a composition comprising a water-soluble polymer in which 50% or more of the hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms, water, and divalent or higher metal ions, wherein the content of the water-soluble polymer is 250 ppm or less.

[0028] The present disclosure also provides a composition comprising a polymer in which 50% or more of the hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms, contains an ionic group, and has an ion exchange rate of 53 or less, water, and divalent or higher metal ions, wherein the content of the polymer is 250 ppm or less.

[0029] In the composition of the present disclosure, the content of divalent or higher metal ions is preferably 0.05 to 1000 mg / L or more.

[0030] The present disclosure then provides a water treatment method characterized by including a step of removing the water-soluble polymer from water containing the water-soluble polymer in which 50% or more of the hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms.

[0031] The present disclosure further provides a water treatment method characterized by including a step of removing the polymer from water containing the polymer in which 50% or more of the hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms, contains an ionic group, and has an ion exchange rate of 53 or less.

Effects of the Invention

[0032] The treatment method of the present disclosure is a novel method and can remove specific polymers such as the above polymer (I).

Modes for Carrying Out the Invention

[0033] Before specifically describing the present disclosure, some terms used in this specification are defined or explained.

[0034] In this specification, unless otherwise specified, "organic group" means a group containing one or more carbon atoms, or a group formed by removing one hydrogen atom from an organic compound. Examples of the "organic group" include an alkyl group which may have one or more substituents, an alkenyl group which may have one or more substituents, an alkynyl group which may have one or more substituents, a cycloalkyl group which may have one or more substituents, a cycloalkenyl group which may have one or more substituents, a cycloalkadienyl group which may have one or more substituents, an aryl group which may have one or more substituents, an aralkyl group which may have one or more substituents, a non-aromatic heterocyclic group which may have one or more substituents, a heteroaryl group which may have one or more substituents, a cyano group, a formyl group, RaO-, RaCO-, RaSO2-, RaCOO-, RaNRaCO-, RaCONRa-, RaOCO- RaOSO2-, and RaNRbSO2- (In these formulas, Ra is independently an alkyl group which may have one or more substituents, an alkenyl group which may have one or more substituents, an alkynyl group which may have one or more substituents, a cycloalkyl group which may have one or more substituents, a cycloalkenyl group which may have one or more substituents, a cycloalkadienyl group which may have one or more substituents, an aryl group which may have one or more substituents, An aralkyl group which may have one or more substituents, A non-aromatic heterocyclic group which may have one or more substituents A heteroaryl group which may have one or more substituents, Rb is independently H or an alkyl group which may have one or more substituents.) including. As the above organic group, an alkyl group which may have one or more substituents is preferable. In this specification, unless otherwise specified, "substituent" means a group that can be substituted. Examples of the "substituent" include an aliphatic group, an aromatic group, a heterocyclic group, an acyl group, an acyloxy group, an acylamino group, an aliphatic oxy group, an aromatic oxy group, a heterocyclic oxy group, an aliphatic oxycarbonyl group, an aromatic oxycarbonyl group, a heterocyclic oxycarbonyl group, a carbamoyl group, an aliphatic sulfonyl group, an aromatic sulfonyl group, a heterocyclic sulfonyl group, an aliphatic sulfonyloxy group, an aromatic sulfonyloxy group, a heterocyclic sulfonyloxy group, a sulfamoyl group, an aliphatic sulfonamide group, an aromatic sulfonamide group, a heterocyclic sulfonamide group, an amino group, an aliphatic amino group, an aromatic amino group, a heterocyclic amino group, an aliphatic oxycarbonylamino group, an aromatic oxycarbonylamino group, a heterocyclic oxycarbonylamino group, an aliphatic sulfinyl group, an aromatic sulfinyl group, an aliphatic thio group, an aromatic thio group, a hydroxy group, a cyano group, a sulfo group, a carboxy group, an aliphatic oxyamino group, an aromatic oxyamino group, a carbamoylamino group, a sulfamoylamino group, a halogen atom, a sulfamoylcarbamoyl group, a carbamoylsulfamoyl group, a di-aliphatic oxyphosphinyl group, and a di-aromatic oxyphosphinyl group. The above aliphatic group may be saturated or unsaturated, and may also have a hydroxy group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the above aliphatic group include an alkyl group having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms, such as a methyl group, an ethyl group, a vinyl group, a cyclohexyl group, a carbamoylmethyl group, etc. The above aromatic group may have, for example, a nitro group, a halogen atom, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the above aromatic group include an aryl group having 6 to 12 carbon atoms, preferably 6 to 10 total carbon atoms, such as a phenyl group, a 4-nitrophenyl group, a 4-acetylaminophenyl group, a 4-methanesulfonylphenyl group, etc. The above heterocyclic group may have a halogen atom, a hydroxy group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the above heterocyclic group include a 5- to 6-membered heterocycle having 2 to 12 total carbon atoms, preferably 2 to 10, such as a 2-tetrahydrofuryl group, a 2-pyrimidyl group, etc. The above acyl group may have an aliphatic carbonyl group, an arylcarbonyl group, a heterocyclic carbonyl group, a hydroxy group, a halogen atom, an aromatic group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the above acyl group include an acyl group having 2 to 8 total carbon atoms, preferably 2 to 4, such as an acetyl group, a propanoyl group, a benzoyl group, a 3-pyridinecarbonyl group, etc. The above acylamino group may have an aliphatic group, an aromatic group, a heterocyclic group, etc., and may have, for example, an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc. Examples of the above acylamino group include an acylamino group having 2 to 12 total carbon atoms, preferably 2 to 8, and an alkylcarbonylamino group having 2 to 8 total carbon atoms, such as an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc. The above aliphatic oxycarbonyl group may be saturated or unsaturated, and may also have a hydroxy group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the above aliphatic oxycarbonyl group include an alkoxycarbonyl group having 2 to 8 carbon atoms in total, preferably 2 to 4 carbon atoms, such as a methoxycarbonyl group, an ethoxycarbonyl group, a (t)-butoxycarbonyl group, etc. The above carbamoyl group may have an aliphatic group, an aromatic group, a heterocyclic group, etc. Examples of the above carbamoyl group include 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. The above aliphatic sulfonyl group may be saturated or unsaturated, and may also have a hydroxy group, an aromatic group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the above aliphatic sulfonyl group include an alkylsulfonyl group having 1 to 6 carbon atoms in total, preferably 1 to 4 carbon atoms, such as methanesulfonyl, etc. The above aromatic sulfonyl group may have a hydroxy group, an aliphatic group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the above aromatic sulfonyl group include an arylsulfonyl group having 6 to 10 carbon atoms in total, such as a benzenesulfonyl group, etc. The above amino group may have an aliphatic group, an aromatic group, a heterocyclic group, etc. The acylamino group may have, for example, an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc. The acylamino group may be 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 propanoylamino group, etc. The aliphatic sulfonamide group, aromatic sulfonamide group, and heterocyclic sulfonamide group may be, for example, a methanesulfonamide group, a benzenesulfonamide group, a 2-pyridinesulfonamide group, etc. The sulfamoyl group may have an aliphatic group, an aromatic group, a heterocyclic group, etc. The sulfamoyl group may be a sulfamoyl group, an alkylsulfamoyl group having 1 to 9 carbon atoms in total, a dialkylsulfamoyl group having 2 to 10 carbon atoms in total, an arylsulfamoyl group having 7 to 13 carbon atoms in total, a heterocyclic sulfamoyl group having 2 to 12 carbon atoms in total, more preferably a sulfamoyl group, an alkylsulfamoyl group having 1 to 7 carbon atoms in total, a dialkylsulfamoyl group having 3 to 6 carbon atoms in total, an arylsulfamoyl group having 6 to 11 carbon atoms in total, a heterocyclic sulfamoyl group having 2 to 10 carbon atoms in total, such as a sulfamoyl group, a methylsulfamoyl group, an N,N-dimethylsulfamoyl group, a phenylsulfamoyl group, a 4-pyridinesulfamoyl group, etc. The aliphatic oxy group may be saturated or unsaturated, and may have a methoxy group, an ethoxy group, an i-propyloxy group, a cyclohexyloxy group, a methoxyethoxy group, etc. The aliphatic oxy group may be an alkoxy group having 1 to 8 carbon atoms in total, preferably 1 to 6 carbon atoms in total, such as a methoxy group, an ethoxy group, an i-propyloxy group, a cyclohexyloxy group, a methoxyethoxy group, etc. The above aromatic amino group and heterocyclic amino group may have an aliphatic group, an aliphatic oxy group, a halogen atom, a carbamoyl group, a heterocyclic group condensed with the aryl group, an aliphatic oxycarbonyl group, preferably an aliphatic group having 1 to 4 carbon atoms in total, an aliphatic oxy group having 1 to 4 carbon atoms in total, a halogen atom, a carbamoyl group having 1 to 4 carbon atoms in total, a nitro group, and an aliphatic oxycarbonyl group having 2 to 4 carbon atoms in total. The above aliphatic thio group may be saturated or unsaturated, and examples thereof include an alkylthio group having 1 to 8 carbon atoms in total, more preferably 1 to 6 carbon atoms in total, such as a methylthio group, an ethylthio group, a carbamoylmethylthio group, a t-butylthio group, and the like. The above carbamoylamino group may have an aliphatic group, an aryl group, a heterocyclic group, etc. Examples of the carbamoylamino group include a carbamoylamino group, an alkylcarbamoylamino group having 2 to 9 carbon atoms in total, a dialkylcarbamoylamino group having 3 to 10 carbon atoms in total, an arylcarbamoylamino group having 7 to 13 carbon atoms in total, a heterocyclic carbamoylamino group having 3 to 12 carbon atoms in total, preferably a carbamoylamino group, an alkylcarbamoylamino group having 2 to 7 carbon atoms in total, a dialkylcarbamoylamino group having 3 to 6 carbon atoms in total, an arylcarbamoylamino group having 7 to 11 carbon atoms in total, a heterocyclic carbamoylamino group having 3 to 10 carbon atoms in total, for example, a carbamoylamino group, a methylcarbamoylamino group, an N,N-dimethylcarbamoylamino group, a phenylcarbamoylamino group, a 4-pyridinecarbamoylamino group, and the like. In the present disclosure, a range represented by endpoints includes all numerical values included within that range (for example, 1 to 10 includes 1.4, 1.9, 2.33, 5.75, 9.98, etc.). In the present disclosure, the description of "at least 1" includes all numerical 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.). In the present disclosure, ppm and ppb are values determined by mass conversion unless otherwise specified. Hereinafter, the processing method of the present disclosure will be described in detail.

[0035] The first processing method of the present disclosure is characterized by including a removal step of removing the polymer (I) from water containing the polymer unit (I) based on the monomer represented by the following general formula (I). CX 1 X 3 =CX 2 R(-CZ 1 Z 2 -A 0 ) m (I) (In the formula, X 1 and X 3 are each independently F, Cl, H, or CF3; X 2 is H, F, an alkyl group, or a fluorinated alkyl group; A 0 is an anionic group; R is a linking group; Z 1 and Z 2 are each independently H, F, an alkyl group, or a fluorinated alkyl group; m is an integer of 1 or more.)

[0036] The above removal step is preferably a step of performing at least one of filtration, adsorption, and aggregation on the water containing the polymer (I). Each of the above filtration, adsorption, and aggregation may be carried out in combination, and each of filtration, adsorption, and aggregation may be repeated a plurality of times.

[0037] (Filtration) The method of the above filtration is not limited. For example, methods such as contacting the water containing the polymer (I) with a filter aid and passing the water containing the polymer (I) through a filter membrane can be mentioned. The temperature in filtration is not particularly limited, and for example, it may be 0 to 50°C.

[0038] (Method of contacting the water containing the polymer (I) with a filter aid) When the water containing the above polymer (I) is filtered, for example, after being brought into contact with a filter aid, or when brought into contact with a filter aid holding member that holds the filter aid, it is separated into the polymer (I) captured by the filter aid and the filtrate. Filter aids are generally used for the purpose of improving filtration characteristics such as reducing filtration resistance and preventing clogging of filter media, and are usually particulate, powdery or fibrous substances. The filter aid functions to capture the polymer (I) in water.

[0039] The above filter aid is not particularly limited, and for example, at least one selected from the group consisting of diatomaceous earth, filter sand (manganese sand, manganese zeolite, activated carbon, anthracite, ceramic sand, etc.), perlite and cellulose is preferred, and diatomaceous earth is more preferred.

[0040] The larger the particle size of the filter aid, the more the increase in filtration pressure is suppressed and the faster the filtration rate becomes, so the amount of water treated per unit time can increase. On the other hand, the smaller the particle size of the filter aid, the higher the effect of capturing the polymer (I), so the concentration of the polymer (I) in the filtrate can be further reduced. The average particle size of the filter aid is preferably 1 to 1000 μm, more preferably 1 to 500 μm, even more preferably 1 to 200 μm, still more preferably 10 to 100 μm, and particularly preferably 20 to 60 μm. Also, when the average particle size of the filter aid is 20 μm or more, preferably 40 μm or more, more preferably 60 μm or more, still more preferably 80 μm or more, the filtration rate can be made faster and the amount of water treated per unit time can be further increased. Also, when the average particle size of the filter aid is 80 μm or less, preferably 60 μm or less, more preferably 40 μm or less, still more preferably 20 μm or less, the effect of capturing the polymer (I) becomes even higher, and the concentration of the polymer (I) contained in the filtrate can be further reduced. Note that the average particle size of the filter aid means the volume-based average particle diameter (volume average particle diameter) measured using a laser diffraction particle size distribution measuring device. As the above-mentioned filter aid, it is particularly preferable that it is diatomaceous earth having an average particle diameter of 20 to 60 μm.

[0041] The filter aid may be added to water containing the polymer (I). Thus, the filtration carried out while directly adding the filter aid to the liquid to be filtered is generally called "body feed". Since body feed can effectively suppress the increase in filtration pressure, it has the advantage that the amount of water treated per unit time can be increased, and a long-term filtration operation can be carried out while maintaining a high filtration rate.

[0042] The above-mentioned filter aid may be used while being held by a filter aid holding member. The filter aid holding member has the function of separating water into the polymer (I) captured by the filter aid and the filtrate (solid-liquid separation) by holding the filter aid. The filter aid holding member may be, for example, a cloth-like member such as a filter cloth, filter paper, and a metal mesh, a porous body such as a sintered metal and a sponge, and a filler such as gravel and sand. The type of the filter aid holding member to be used can be appropriately selected according to conditions such as the water to be treated.

[0043] For example, a layer of the filter aid may be formed on the surface of the filter aid holding member. Thus, forming a layer of the filter aid on the surface of the filter aid holding member before filtration is generally called "precoat". Since precoat can effectively prevent clogging of the filter aid holding member, it can suppress the increase in filtration pressure, and as a result, the amount of water treated per unit time can be increased.

[0044] The pore size of the filter aid holding member can be appropriately set according to the particle size of the filter aid to be used. The pore size of the filter aid holding member may be, for example, 1 to 1000 μm. The smaller the pore size of the filter aid holding member, the more reliably the filter aid can be held. On the other hand, the larger the pore size of the filter aid holding member, the lower the pressure loss during filtration can be reduced. When using diatomaceous earth as the filter aid, the pore size of the filter aid holding member is preferably smaller than the average particle size of the filter aid, and for example, preferably 60% or less of the average particle size of the filter aid. The material constituting the filter aid holding member is not particularly limited, and may be, for example, synthetic fibers such as polypropylene, polyester, polyamide, polyimide, polyacrylonitrile, polytetrafluoroethylene (PTFE), polyphenylene sulfide (PPS), vinylidene chloride, and vinylon, glass fibers, cotton, etc.

[0045] In the first treatment method of the present disclosure, body feed or precoat may be performed alone, or body feed and precoat may be combined. By combining body feed and precoat, the polymer (I) in water can be captured more efficiently, and furthermore, the increase in filtration pressure can be suppressed more effectively, so that the polymer (I) can be removed with high efficiency over a long period of time.

[0046] The amount of the filter aid can be appropriately set according to the water to be treated, the type of the filter aid used, etc., and is not limited to a specific amount. As an example, the amount of the filter aid added to water in body feed may be such that the concentration of the filter aid in the water containing the polymer (I) is 1 to 10000 ppm, preferably 10 to 1000 ppm, more preferably 20 to 100 ppm. The amount of the filter aid used in precoat may be such that the thickness of the filter aid layer formed on the surface of the filter aid holding member is 0.5 to 10 mm, preferably 1 to 7 mm.

[0047] (Method of passing water containing polymer (I) through a filtration membrane) By passing water containing polymer (I) through a filtration membrane, polymer (I) contained in the water can be removed. The type of the filtration membrane is not particularly limited and may be appropriately selected according to water containing polymer (I), filtration conditions, etc. As the filtration membrane, any one of a reverse osmosis membrane, a nanofiltration membrane, a filter paper, a microfiltration membrane, or an ultrafiltration membrane may be used, or two or more types of filtration membranes may be used in combination. Specifically, a filtration membrane with a pore size of 0.05 nm to 25 μm can be used. Further, as the reverse osmosis membrane, the nanofiltration membrane, or the ultrafiltration membrane, a filtration membrane with a pore size of 0.05 nm to 0.5 μm can be used. The filtration membrane may, for example, have an NaCl rejection rate of 10% or more. The NaCl rejection rate is a value calculated by the following formula after filtering an NaCl solution (raw water) through a filtration membrane to obtain permeated water and measuring the NaCl concentrations of the raw water and the permeated water. NaCl rejection rate (%) = (1 - (NaCl concentration of permeated water) / (NaCl concentration of raw water)) × 100 The shape of the filtration membrane is not particularly limited and may be, for example, a flat membrane, a spiral shape, or a tubular shape. Further, when a plurality of filtration membranes are used in combination, single membranes may be arranged in series, or a so-called composite membrane in which a plurality of membranes are laminated in advance may be used. In membrane filtration, the filtration pressure may be appropriately set according to the water to be treated, the type of the filtration membrane used, etc.

[0048] The above filtration is preferably pressure filtration. By performing pressure filtration, the polymer (I) can be removed more efficiently. Known apparatuses can be appropriately used for pressure filtration. For example, pressure filtration may be performed using a pressure filter equipped with a candle type filter. When a pressure filtration apparatus is used, by applying an internal pressure, the cake layer formed on the surface of the filter aid holding member can be periodically peeled off, and water treatment can be stably performed over a long period of time. As an alternative method, water may be separated from the polymer (I) by vacuum filtration. When performing pressure filtration or vacuum filtration, the filtration pressure can be appropriately set according to the water to be treated, the filter aid used, the filter aid holding member, and the type of filtration apparatus, etc.

[0049] (Adsorption) The above adsorption can be performed by bringing water containing the polymer (I) into contact with an adsorbent. As a method of bringing water containing the polymer (I) into contact with the adsorbent, a commonly adopted method can be employed. For example, it can be carried out by a method of adding an adsorbent to water containing the polymer (I) and stirring, a column method of flowing water containing the polymer (I) through a column filled with an adsorbent, etc. The packed column used in the column method may be any of a mobile type, a fixed bed type, or a fluidized bed type. When using the method of adding an adsorbent to water containing the polymer (I) and stirring, it is preferable to separate the adsorbent that has adsorbed the polymer (I) from the water after adsorption after stirring. The method of the above separation is not limited, and for example, filtration etc. can be used. As the method of filtration, the methods described above can be used as the method of performing filtration on water containing the polymer (I).

[0050] The above adsorbent is not particularly limited, but for example, at least one selected from the group consisting of ion exchange resins, chelating agents, synthetic adsorbents, activated carbon, silica gel, clay, and zeolite is preferable. Also, as the adsorbent, alumina, carbon nanotubes, etc. can also be used. It is more preferable that the adsorbent is at least one selected from the group consisting of ion exchange resins, chelating agents, synthetic adsorbents, and activated carbon. By using an ion exchange resin, a chelating agent, a synthetic adsorbent, or activated carbon as the adsorbent, the adsorption rate of the polymer (I) can be improved. As the adsorbent, an ion exchange resin is more preferably used. By using an ion exchange resin, the adsorption rate of the polymer (I) can be further increased. For the above adsorption, one type of adsorbent may be used alone, or two or more types of adsorbents may be used in combination.

[0051] The ion exchange resin may be either a cation exchange resin or an anion exchange resin. As the anion exchange resin, for example, an ion exchange resin having an amino group and / or a quaternary ammonium group as a functional group can be used. The ion exchange resin is preferably a strongly basic anion exchange resin. The basicity of the anion exchange resin can be variously set depending on the type of the polymer skeleton and / or the functional group. Commercially available products can be used as the anion exchange resin. For example, Diaion (trademark) SA series manufactured by Mitsubishi Chemical Corporation, A200, A300, PFA694E, etc. manufactured by Purolite Corporation, Amberlite (trademark) series manufactured by Organo Corporation, Amberjet (trademark) series such as IRA4002OH, can be used. As the cation exchange resin, for example, an ion exchange resin having a carboxylic acid group and / or a sulfonic acid group as a functional group can be used. The acidity of the cation exchange resin can be variously set depending on the type of the polymer skeleton and / or the functional group. Commercially available products can be used as the cation exchange resin. For example, Diaion (trademark) SK series manufactured by Mitsubishi Chemical Corporation, C100 manufactured by Purolite Corporation, Amberlite (trademark) series manufactured by Organo Corporation, etc. can be used. The ion exchange resin preferably has a pore diameter of 1 to 5000 Å. From the viewpoint of removal efficiency, the pore diameter is preferably 50 Å or more, more preferably 100 Å or more, and even more preferably 150 Å or more. Also, it may be 200 Å or more, or 250 Å or more. Further, the pore diameter may be 1000 Å or less. The pore diameter can be measured and calculated by, for example, the gas adsorption method for the specific surface area and total pore volume. From the viewpoint of removal efficiency, the ion exchange resin preferably has a total exchange capacity of 0.1 eq / L-Resin or more. More preferably, it is 0.5 eq / L-Resin or more, and still more preferably, it is 0.9 eq / L-Resin or more. Also, although the larger the total exchange capacity is, the better, for example, the upper limit may be 5.0 eq / L-Resin. Also, the ion exchange resin is usually spherical and has an average particle diameter of about 300 to 1300 μm.

[0052] The above chelating agent is usually a compound having a multidentate ligand capable of coordinating with metal ions to form a chelate compound. The material and whether it is a gel type or an MR type are not limited. For example, resins obtained by introducing functional groups into styrene-divinylbenzene copolymers, phenol polymers, etc. can be mentioned. Examples of the chelating agent include aminophosphonic acid types such as iminodiacetic acid type, iminopropionic acid type, aminomethylenephosphonic acid type, polyamine type, aminocarboxylic acid type, dithiocarbamic acid type, thiol type, amidoxime type, pyridine type, etc. The above chelating agent is preferably spherical and may have an average particle diameter of about 300 to 1300 μm. Specific examples of the chelating agent include the "Uniselec" (trade name) series (manufactured by Unitika Ltd.), the "Lewatit" (trade name) series (manufactured by Lanxess Co., Ltd.), the "Epolas" (registered trademark) (trade name) series (manufactured by Miyoshi Oil & Fat Co., Ltd.) (Z-7, Z-100, SE-3, AS-4), etc.

[0053] The above synthetic adsorbent is a porous resin without an ion-exchange group, and a known one known as a synthetic adsorbent can be adopted. Examples of the ion-exchange group include an amino group, a quaternary ammonium group, a carboxylic acid group, a sulfonic acid group, and the like. Specific examples of the synthetic adsorbent include styrene resins such as styrene-divinylbenzene copolymers, acrylic resins such as (meth)acrylate-ethylene glycol dimethacrylate copolymers, methacrylic resins, polyvinyl resins, dextran resins, and the like. Specifically, commercially available synthetic adsorbents include, as styrene resins, Diaion HP10, Diaion HP20, Diaion HP21, Diaion HP40, Diaion HP50, Sepabeads SP207, Sepabeads SP70, Sepabeads SP825, Sepabeads SP850, Sepabeads SP207 (manufactured by Mitsubishi Chemical Corporation), Amberlite XAD1180N, Amberlite XAD2000, Amberlite XAD4, Amberlite FPX66 (manufactured by Organo Corporation), etc.; as acrylic resins, Diaion HP2MG (manufactured by Mitsubishi Chemical Corporation), Amberlite HXAD-7HP (manufactured by Organo Corporation), and the like. The synthetic adsorbent preferably has a pore diameter of 1 to 5000 Å. From the viewpoint of removal efficiency, the pore diameter is preferably 50 Å or more, more preferably 100 Å or more, and still more preferably 150 Å or more. Also, it may be 200 Å or more, or 250 Å or more. Also, the pore diameter may be 1000 Å or less. The pore diameter can be measured and calculated by, for example, the gas adsorption method for the specific surface area and the total pore volume. The synthetic adsorbent preferably has a specific surface area of 300 m 2 / g or more. The specific surface area is more preferably 400 m 2 / g or more, still more preferably 500 m 2 / g or more, and particularly preferably 600 m 2 / g or more. The upper limit of the specific surface area is not limited, but it may be, for example, 2000 m 2 / g or less, 1500 m 2 / g or less, or 1000 m 2 / g or less. In addition, the synthetic adsorbent is usually spherical and has an average particle diameter of about 200 to 1300 μm.

[0054] The activated carbon can be produced from carbonaceous materials. Examples of carbonaceous materials include those that can produce activated carbon through carbonization, activation, etc., such as plant-based materials like wood, sawdust, charcoal, coconut shells, fruit shells like walnut shells, fruit seeds, peat, lignite, brown coal, bituminous coal, anthracite, etc., pitches such as petroleum pitch, coal pitch, tars such as coke, coal tar, petroleum tar, mineral-based materials such as petroleum distillation residues, natural materials such as cellulose fibers like cotton, rayon, and synthetic materials such as phenolic resins, polyvinyl alcohol, polyacrylonitrile, etc. The shape can be any of powdery, granular, fibrous, or those formed from them.

[0055] The above-mentioned activated carbon preferably has a specific surface area of 500 m 2 / g or more. The specific surface area is more preferably 1000 m 2 / g or more, still more preferably 1500 m 2 / g or more, particularly preferably 1800 m 2 / g or more, and especially preferably 2000 m 2 / g or more. The upper limit of the specific surface area is not limited, for example, it may be 2500 m 2 / g. The shape of the activated carbon is not particularly limited and may be, for example, pellet-shaped, granular, powdery, or spherical particle-shaped. The activated carbon may be a commercially available product. Examples of commercially available activated carbon include, for example, Shirasagi (trademark) manufactured by Osaka Gas Chemical Co., Ltd., Filtrasorb (trademark) CAL, Diahope (trademark), Diasorb (trademark) manufactured by Calgon Carbon Japan Co., Ltd., and the Evadia (trademark) series manufactured by Suisho Co., Ltd.

[0056] When using activated carbon as the adsorbent, it is preferable that the activated carbon is highly activated activated carbon. By using highly activated activated carbon, the adsorption rate of polymer (I) can be increased compared to ordinary activated carbon. The above-mentioned activated carbon preferably has improved adsorption performance by performing steam activation treatment. In the steam activation treatment, it is preferable to expose the activated carbon to steam at a temperature of 120 °C or higher, for example, 130 to 350 °C, particularly 150 to 1000 °C, and a pressure of 0.2 MPa or higher, for example, 0.5 to 15 MPa, particularly 1 MPa to 15 MPa. The steam activation treatment time may generally be 10 seconds to 50 hours, for example, 10 minutes to 10 hours. In the activation, heating in the furnace may be performed. Cations may be attached to the surface of the activated carbon. Examples of cations include metal ions, metal oxide ions, ammonium ions, etc. Examples of metals include metal atoms of Groups 1 to 13 of the periodic table (for example, alkali metals (for example, Li, Na, K), alkaline earth metals (for example, Mg, Ca), Ti, Zr, V, Cr, Fe, Ni, Cu, Zn).

[0057] In the above adsorption, the amount of the adsorbent with respect to the water containing polymer (I) is not limited, but for example, it may be 0.01 to 1000 g with respect to 1000 g of the water containing polymer (I). With respect to 1000 g of the water containing polymer (I), 0.1 g or more is preferable, 1 g or more is more preferable, and 5 g or more is still more preferable. Also, 500 g or less is preferable.

[0058] The temperature in the above adsorption is not particularly limited, but for example, it may be 0 to 50 °C.

[0059] The adsorption device that can be used in the above adsorption is not particularly limited as long as it is an adsorption device equipped with the above-mentioned adsorbent, and various adsorption devices may be appropriately used according to the purpose. The adsorption device may be, for example, a packed tower filled with the adsorbent, and specifically, it may be an ion exchange tower or an activated carbon tower.

[0060] In the first treatment method of the present disclosure, after adsorbing the polymer (I) onto the adsorbent, it is preferable to recover the adsorbent. The above recovery method is not particularly limited and a conventionally known method may be used. For example, the adsorbent adsorbed with the polymer (I) may be separated by the above-described filtration.

[0061] (Coagulation) Among the above filtration, adsorption, and coagulation, coagulation is preferable because the removal efficiency of the polymer (I) can be further improved. The above coagulation can be carried out, for example, by adding a coagulant to the water containing the polymer (I). The above removal step is preferably a step of adding a coagulant to the water containing the polymer (I). In the above removal step, after adding a coagulant to the water containing the polymer (I), it is preferable to stir. The stirring time is not limited and may be appropriately set according to the amount of the polymer (I) in the water and the addition amount of the coagulant. The stirring time may be appropriately set, for example, in the range of 0 minutes to 100 hours.

[0062] Examples of the above coagulant include inorganic coagulants, organic coagulants, polymer coagulants, and the like. The addition amount of the above coagulant may be appropriately selected according to the amount of the polymer (I) contained in the water, the type of the coagulant, etc., but may be, for example, 300% by weight or less with respect to the polymer (I), and may be 0.01% by weight or more. In addition, it may be 50% by weight or more, and may also be 0.01% by weight or less.

[0063] The above removal step is particularly preferably a step of adding an inorganic coagulant to the water containing the polymer (I). The above removal step is for coagulating the polymer (I), and is one of the preferred embodiments which is a step of adding an inorganic coagulant to the water containing the polymer (I). Examples of the above inorganic coagulant include metal salts, etc., and commercially available products may be used. Seawater containing Mg 2+ , Ca 2+ , etc., and low molecular weight cationic polymer coagulants can also be used. The addition amount of the above inorganic flocculant is preferably 0.01% by weight or more, more preferably 0.04% by weight or more, still more preferably 0.1% by weight or more, particularly preferably 1% by weight or more, especially preferably 5% by weight or more, and most preferably 10% by weight or more, based on the polymer (I). Also, it is preferably 300% by weight or less, preferably 50% by weight or less, more preferably 30% by weight or less, and still more preferably 20% by weight or less, based on the polymer (I). The addition amount of the above inorganic flocculant is preferably 1 ppm by weight or more, more preferably 10 ppm by weight or more, still more preferably 20 ppm by weight or more, based on the water containing the polymer (I). Also, it is preferably 15000 ppm by weight or less, more preferably 10000 ppm by weight or less, and still more preferably 5000 ppm by weight or less.

[0064] The above inorganic flocculant is preferably a metal salt. As the inorganic flocculant which is the above metal salt, a metal salt containing a divalent or higher metal element is preferred. The valence of the metal element constituting the metal salt is preferably 2 or higher, more preferably 3 or higher, and may be 3. The upper limit of the valence of the metal element constituting the metal salt is not particularly limited, and may be, for example, 6 or lower. Here, the divalent or higher metal element constituting the metal salt is more preferably at least one metal element selected from the group consisting of Fe, Al, and Ca, still more preferably at least one metal element selected from the group consisting of Fe and Al, and particularly preferably Al. Also, as the counter ion of the metal element constituting the metal salt, at least one selected from the group consisting of sulfate ion, hydroxide ion, fluoride ion, nitrate ion, and chloride ion is more preferred, at least one selected from the group consisting of sulfate ion and chloride ion is still more preferred, and sulfate ion is particularly preferred. In this specification, "metal salt" means a simple salt, double salt, and / or complex salt. Also, "salt containing a divalent or higher metal element" means a simple salt, double salt, and / or complex salt containing a divalent or higher metal element.

[0065] As the above metal salt, for example, at least one metal salt selected from the group consisting of aluminum salts (such as aluminum sulfate, polyaluminum chloride, etc.), iron salts (such as ferrous hydroxide, ferric hydroxide, ferrous sulfate, ferric sulfate, polyferric sulfate, etc.), calcium salts (such as calcium hydroxide, calcium chloride, calcium sulfate, calcium carbonate, calcium nitrate, calcium fluoride, etc.), and silicate minerals containing a divalent or higher metal element and silicon (such as kaolinite, montmorillonite, zeolite, etc.) is preferred. As the above silicate mineral, as a commercially available flocculant, silica-alumina-based flocculants can be mentioned. For example, Florinite 723, Florinite 113, Florinite 101, Florinite S, Florinite D, etc. manufactured by Nippon Activated Clay Co., Ltd. can be mentioned. Note that the metal salt that can be used as a flocculant may be in a mode of generating a metal salt or converting the counter ion of the metal element of the metal salt in the step of adding the flocculant. As such a mode, for example, a mode of adding a metal salt having a counter ion such as a metal hydroxide to water containing the polymer (I) can be mentioned. In such a mode, conversion of the counter ion of the metal salt occurs. When the conversion of the counter ion of the metal salt occurs, a better impurity removal effect may be obtained.

[0066] As the above inorganic flocculant, at least one metal salt selected from the group consisting of iron salts and aluminum salts is preferred, at least one metal salt selected from the group consisting of ferric chloride, aluminum sulfate, and polyaluminum chloride is more preferred, at least one aluminum salt selected from the group consisting of aluminum sulfate and polyaluminum chloride is still more preferred, and aluminum sulfate is particularly preferred.

[0067] Examples of the above-mentioned polymer flocculants include sodium alginate, chitin / chitosan flocculants, cationic polymer flocculants, anionic polymer flocculants, amphoteric polymer flocculants, nonionic polymer flocculants, etc. It is preferably at least one selected from the group consisting of cationic polymer flocculants, anionic polymer flocculants, amphoteric polymer flocculants, and nonionic polymer flocculants.

[0068] The addition amount of the above-mentioned polymer flocculant is preferably 0.001% by weight or more, more preferably 0.004% by weight or more, and particularly preferably 0.01% by weight or more with respect to the polymer (I). The upper limit value of the addition amount of the polymer flocculant is not particularly limited, and it is preferably 50% by weight or less, more preferably 30% by weight or less, and particularly preferably 20% by weight or less with respect to the polymer (I). The addition amount of the above-mentioned polymer flocculant is preferably 0.1 ppm by weight or more, more preferably 1 ppm by weight or more, and still more preferably 2 ppm by weight or more with respect to the water containing the polymer (I). Also, it is preferably 15000 ppm by weight or less, more preferably 10000 ppm by weight or less, and still more preferably 5000 ppm by weight or less.

[0069] Examples of the above-mentioned cationic polymer flocculants include polyaminoalkyl methacrylates such as dimethylaminoethyl methacrylate, polyethyleneimine, polydiallylammonium halides, chitosan, urea-formalin resins, etc. Examples of commercially available cationic polymer flocculants include Takifloc C-403, C-408, C-805, C-806, C-809 manufactured by Taki Chemical Co., Ltd.; Aronfloc EC-509L, C-508, CX-400, C-303, CX-333 manufactured by MT Aqua Polymer Co., Ltd., etc.

[0070] Examples of the above-mentioned anionic polymer flocculants include polyacrylamide-based polymer flocculants such as sodium polyacrylate, partially hydrolyzed polyacrylamide, partially sulfomethylated polyacrylamide, poly(2-acrylamido)-2-methylpropane sulfate, etc. Examples of commercially available anionic polymer flocculants include Floclan A1210 manufactured by Katayama Nalco Co., Ltd.; Takifloc A-102, A-103, A-177T, A-108T, A-142, A-50 manufactured by Taki Chemical Co., Ltd.; Akofloc A-95, A-110, A-150 manufactured by MT Aquapolymer Co., Ltd.; Sumifloc FA-40, FA-50 manufactured by MT Aquapolymer Co., Ltd.; Diafloc AP199, Ap120C, Ap784, DF732B, etc. manufactured by Mitsubishi Chemical Corporation.

[0071] Examples of the above nonionic polymer flocculants include polyacrylamide, polyethylene oxide, etc. Examples of commercially available nonionic polymer flocculants include Takifloc N-100T, N-131, A-122T manufactured by Taki Chemical Co., Ltd.; Akofloc N-100, N-210 manufactured by MT Aquapolymer Co., Ltd.; Sumifloc FN-10H, FN-20H manufactured by MT Aquapolymer Co., Ltd.; Diafloc NP500, NP780, DF500, etc. manufactured by Mitsubishi Chemical Corporation.

[0072] Examples of the above amphoteric polymer flocculants include copolymers of acrylamide, aminoalkyl methacrylate, and sodium acrylate. Examples of commercially available amphoteric polymer flocculants include Takifloc MC-601, MC-602, MC-603 manufactured by Taki Chemical Co., Ltd.; Diafloc KA003, KA606A, etc. manufactured by Mitsubishi Chemical Corporation.

[0073] Among the above polymer flocculants, anionic polymer flocculants are preferred.

[0074] The temperature in the above flocculation is not particularly limited. For example, 0°C or higher is preferred, 5°C or higher is more preferred, and 10°C or higher is even more preferred. Also, 50°C or lower is preferred, 40°C or lower is more preferred, and 30°C or lower is even more preferred.

[0075] In the above removal step, only an inorganic flocculant may be added as the flocculant, only a polymer flocculant may be added, or both an inorganic flocculant and a polymer flocculant may be added. Also, the inorganic flocculant and the polymer flocculant may be added simultaneously, the polymer flocculant may be added after the inorganic flocculant is added, or the inorganic flocculant may be added after the polymer flocculant is added. Furthermore, the polymer flocculant and the inorganic flocculant may be added in multiple portions, or the polymer flocculant and the inorganic flocculant may be added alternately.

[0076] It is particularly preferable that the above removal step is a step of adding an inorganic flocculant to water containing the polymer (I) and then adding a polymer flocculant. By adding the inorganic flocculant, the surface charge of the polymer (I) is neutralized by the opposite charge to cause aggregation and form flocs. Thereafter, by adding a polymer flocculant to coarsen the flocs, the flocs aggregated with the inorganic flocculant can be crosslinked to form coarse flocs, whereby the polymer (I) can be removed more efficiently. In this case, the addition amount of the inorganic flocculant is preferably 0.01% by weight or more, more preferably 0.04% by weight or more, still more preferably 0.1% by weight or more, particularly preferably 1% by weight or more, most preferably 5% by weight or more, and most preferably 10% by weight or more with respect to the polymer (I). Also, it is preferably 300% by weight or less, more preferably 50% by weight or less, still more preferably 30% by weight or less, particularly preferably 20% by weight or less. The addition amount of the above inorganic flocculant is preferably 1 ppm by weight or more, more preferably 10 ppm by weight or more, still more preferably 20 ppm by weight or more with respect to the water containing the polymer (I). Also, it is preferably 15000 ppm by weight or less, more preferably 10000 ppm by weight or less, still more preferably 5000 ppm by weight or less. The addition amount of the polymer flocculant is preferably 0.001% by weight or more, more preferably 0.004% by weight or more, and particularly preferably 0.01% by weight or more with respect to the polymer (I). Also, it is preferably 50% by weight or less, more preferably 30% by weight or less, and still more preferably 20% by weight or less. The addition amount of the above polymer flocculant is preferably 0.1 ppm by weight or more, more preferably 1 ppm by weight or more, and still more preferably 2 ppm by weight or more with respect to the water containing the polymer (I). Also, it is preferably 15000 ppm by weight or less, more preferably 10000 ppm by weight or less, and still more preferably 5000 ppm by weight or less.

[0077] In the above removal step, it is also preferable to add a pH adjuster to the water containing the polymer (I) to adjust the pH after adding an inorganic flocculant to the water containing the polymer (I) and before adding the polymer flocculant. By adjusting the pH, the polymer (I) can be removed more efficiently. In the above removal step, before adding the polymer flocculant, it is preferable to make the above pH 4.0 or more, more preferably 5.0 or more, and still more preferably 6.0 or more. Also, it is preferable to make the above pH 11.0 or less, more preferably 9.0 or less, and still more preferably 8.0 or less. The pH adjuster is not limited, and for example, an acid compound or an alkali compound can be used. Examples of the above acid compound include hydrochloric acid (HCl), nitric acid (HNO3), sulfuric acid (H2SO4), phosphoric acid (H3PO4), etc., and particularly, hydrochloric acid (HCl) or nitric acid (HNO3) is preferable. Examples of the alkali compound include hydroxides of alkali metals such as NaOH and KOH; hydroxides of alkaline earth metals such as Mg(OH)2 and Ca(OH)2; salts with buffering action such as disodium hydrogen phosphate, etc. Examples of the organic compound include ammonia, amines, etc. The above pH can be measured by a pH meter (for example, pH meter D-20 manufactured by Horiba).

[0078] In the first treatment method of the present disclosure, it is preferable to perform aggregation in water containing polymer (I), and after aggregating polymer (I), remove the aggregated polymer (I) from the water containing polymer (I). The method for removing the aggregated polymer (I) from the water containing polymer (I) is not limited, and examples include filtration and the like. The method of the above filtration is not limited, and the methods described above can be appropriately adopted. In the first treatment method of the present disclosure, it is preferable to recover the aggregated polymer (I) after aggregating the above polymer (I). The method of recovery is not limited, and examples include filtration and the like. The method of the above filtration is not limited, and the methods described above can be appropriately adopted.

[0079] The above removal step is particularly preferably a step of adding an inorganic flocculant to the water containing polymer (I), then adding a polymer flocculant, and filtering the water containing the aggregated polymer (I). In this aspect, after adding an inorganic flocculant to the water containing polymer (I), before adding a polymer flocculant, a pH adjuster may be added to the water containing polymer (I) to adjust the pH. The above pH can adopt the above range, and for example, it is also preferable to adjust the pH to 5.0 to 9.0 (preferably 6.0 to 8.0).

[0080] The above removal step is preferably a step of reducing the concentration of polymer (I) in the water containing polymer (I) to 50% or less with respect to the concentration before the removal step. More preferably, it is 40% or less, still more preferably 30% or less, particularly preferably 20% or less, and especially preferably 10% or less.

[0081] The above removal step is also preferably a step of reducing the concentration of polymer (I) in the treated water to 250 ppm or less. More preferably, it is 200 ppm or less, still more preferably 100 ppm or less, still more preferably 80 ppm or less, particularly preferably 60 ppm or less, and especially preferably 50 ppm or less.

[0082] By the above removal step, dimers and trimers of the monomers forming the structural units constituting the polymer (I) can also be removed from the water containing the polymer (I).

[0083] The dimers and trimers may be dimers and trimers of the monomer represented by the general formula (I) (hereinafter sometimes referred to as monomer (I)). The dimers and trimers may be polymers formed from one kind of monomer (I) as the monomer (I) represented by the general formula (I), or may be copolymers formed from two or more kinds of monomer (I) having different structures. Further, examples of the dimers and trimers include dimers and trimers of the monomers that form the preferred structural units constituting the polymer (I).

[0084] The above polymer (I) contains a polymerization unit (I) based on the monomer represented by the following general formula (I). It is preferable that the polymer (I) contains two or more polymerization units (I). CX 1 X 3 =CX 2 R(-CZ 1 Z 2 -A 0 ) m (I) (In the formula, X 1 and X 3 are each independently F, Cl, H or CF3; X 2 is H, F, an alkyl group or a fluorine-containing alkyl group; A 0 is an anionic group; R is a linking group; Z 1 and Z 2 are each independently H, F, an alkyl group or a fluorine-containing alkyl group; m is an integer of 1 or more.) X 2 is preferably F, Cl, H or CF3. Further, Z 1 and Z 2 are preferably F or CF3. In the present disclosure, the anionic group includes, in addition to anionic groups such as sulfate groups and carboxylate groups, functional groups that give anionic groups such as acid groups like -COOH and acid-base groups like -COONH4. The above anionic group is a sulfate group, a carboxylate group, a phosphate group, a phosphonate group, a sulfonate group, or -C(CF3)2OM (wherein M is -H, a metal atom, -NR 7 4, which may be an optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, and R 7 is H or an organic group.). Preferably, it is a sulfate group, a carboxylate group, a phosphate group, a phosphonate group, or a sulfonate group. The polymer (I) may contain only the polymerization unit (I) based on one kind of monomer represented by the general formula (I), or may contain the polymerization unit (I) based on two or more kinds of monomers represented by the general formula (I).

[0085] The above R is a linking group. In the present disclosure, the "linking group" is a (m + 1)-valent linking group, and when m is 1, it refers to a divalent linking group. The linking group may be a single bond, preferably contains at least one carbon atom, and the number of carbon atoms may be 2 or more, 4 or more, 8 or more, 10 or more, or even 20 or more. The upper limit is not limited, but for example, it may be 100 or less, or 50 or less. The linking group may be linear or branched-chain, cyclic or acyclic structure, saturated or unsaturated, substituted or unsubstituted, and optionally contains one or more heteroatoms selected from the group consisting of sulfur, oxygen, and nitrogen, and optionally contains one or more functional groups selected from the group consisting of ester, amide, sulfonamide, carbonyl, carbonate, urethane, urea, and carbamate. The above linking group may not contain a carbon atom and may be a catenary heteroatom such as oxygen, sulfur, or nitrogen. m is an integer of 1 or more, preferably 1 or 2, and more preferably 1. When m is an integer of 2 or more, Z 1 , Z 2 and A0 may be the same or different. Next, a preferred configuration when m is 1 in the general formula (I) will be described.

[0086] The above R is preferably, for example, a catenary heteroatom such as oxygen, sulfur, nitrogen, or a divalent organic group. When R is a divalent organic group, the hydrogen atom bonded to the carbon atom may be replaced with a halogen other than fluorine, such as chlorine, and may or may not contain a double bond. Also, R may be either linear or branched, and may be either cyclic or acyclic. Further, R may contain a functional group (for example, ester, ether, ketone, amine, halide, etc.). R may also be a non-fluorinated divalent organic group or a partially fluorinated or perfluorinated divalent organic group. Examples of R include a hydrocarbon group in which no fluorine atom is bonded to a carbon atom, a hydrocarbon group in which a part of the hydrogen atoms bonded to the carbon atoms are replaced with fluorine atoms, or a hydrocarbon group in which all of the hydrogen atoms bonded to the carbon atoms are replaced with fluorine atoms. These may contain an oxygen atom, may contain a double bond, and may contain a functional group.

[0087] R is preferably a hydrocarbon group having 1 to 100 carbon atoms which may contain an ether bond, and a part or all of the hydrogen atoms bonded to the carbon atoms of the hydrocarbon group may be replaced with fluorine. Preferably as R, -(CH2) a -,-(CF2) a -,-O-(CF2) a -,-(CF2) a -O-(CF2) b -,-O(CF2) a -O-(CF2) b -,-(CF2) a -[O-(CF2) b c -,-O(CF2) a -[O-(CF2) b c ​​-, -[(CF2) a -O] b -[(CF2) c -O] d -, -O[(CF2) a -O] b -[(CF2) c -O] d -, -O-[CF2CF(CF3)O] a -(CF2) b -, -[CF2CF(CF3)O] a -, -[CF(CF3)CF2O] a -, -(CF2) a -O-[CF(CF3)CF2O] a -, -(CF2) a -O-[CF(CF3)CF2O] a -(CF2) b -, and at least one selected from the combinations thereof. In the formula, a, b, c, and d are each independently at least 1 or more. a, b, c, and d may each independently be 2 or more, 3 or more, 4 or more, 10 or more, 20 or more. The upper limit of a, b, c, and d is, for example, 100.

[0088] R is preferably a divalent group represented by the following general formula (r1): -CF2-O-(CX 6 2) e -{O-CF(CF3)} f -(O) g - (r1) (In the formula, X 6 is each independently H, F, or CF3, e is an integer from 0 to 3, f is an integer from 0 to 3, and g is 0 or 1), and preferably a divalent group represented by the following general formula (r2): -CF2-O-(CX 7 2) e -(O) g - (r2) (In the formula, X 7 is each independently H, F, or CF3, e is an integer from 0 to 3, and g is 0 or 1).

[0089] Specific examples suitable as R include -CF2-O-, -CF2-O-CF2-, -CF2-O-CH2-, -CF2-O-CH2CF2-, -CF2-O-CF2CF2-, -CF2-O-CF2CH2-, -CF2-O-CF2CF2CH2-, -CF2-O-CF(CF3)-, -CF2-O-CF(CF3)CF2-, -CF2-O-CF(CF3)CF2-O-, -CF2-O-CF(CF3)CF2-O-CF2-, -CF2-O-CF(CF3)CH2-, and the like. Among them, the above R is preferably a perfluoroalkylene group which may contain an oxygen atom. Specifically, -CF2-O-, -CF2-O-CF2-, -CF2-O-CF2CF2-, -CF2-O-CF(CF3)-, -CF2-O-CF(CF3)CF2-, or -CF2-O-CF(CF3)CF2-O- is preferable.

[0090] -R-CZ in the general formula (I) 1 Z 2 As - -CF2-O-(CX 6 2) e -{O-CF(CF3)} f -(O) g -CZ 1 Z 2 - (s1) (In the formula, X 6 is independently H, F or CF3, e is an integer from 0 to 3, f is an integer from 0 to 3, g is 0 or 1, and Z 1 and Z 2 are each independently H, F, an alkyl group or a fluorine-containing alkyl group), and the divalent group represented by this is preferable. In the formula (s1), Z 1 and Z 2 are more preferably F or CF3, and it is even more preferable that one is F and the other is CF3. Also, in the general formula (I), as -R-CZ 1 Z 2 - -CF2-O-(CX 7 2) e -(O) g -CZ 1Z 2 - (s2) (wherein X 7 is each independently H, F or CF3, e is an integer from 0 to 3, g is 0 or 1, Z 1 and Z 2 are each independently preferably a divalent group represented by F or CF3), and in formula (s2), Z 1 and Z 2 more preferably, one is F and the other is CF3.

[0091] -R-CZ 1 Z 2 - in the general formula (I) is preferably -CF2-O-CF2-, -CF2-O-CF(CF3)-, -CF2-O-C(CF3)2-, -CF2-O-CF2-CF2-, -CF2-O-CF2-CF(CF3)-, -CF2-O-CF2-C(CF3)2-, -CF2-O-CF2CF2-CF2-, -CF2-O-CF2CF2-CF(CF3)-, -CF2-O-CF2CF2-C(CF3)2-, -CF2-O-CF(CF3)-CF2-, -CF2-O-CF(CF3)-CF(CF3)-, -CF2-O-CF(CF3)-C(CF3)2-, -CF2-O-CF(CF3)-CF2-, -CF2-O-CF(CF3)-CF(CF3)-, -CF2-O-CF(CF3)-C(CF3)2-, -CF2-O-CF(CF3)CF2-CF2-, -CF2-O-CF(CF3)CF2-CF(CF3)-, -CF2-O-CF(CF3)CF2-C(CF3)2-, -CF2-O-CF(CF3)CF2-O-CF2-, -CF2-O-CF(CF3)CF2-O-CF(CF3)-, or -CF2-O-CF(CF3)CF2-O-C(CF3)2-, and more preferably -CF2-O-CF(CF3)-, -CF2-O-CF2-CF(CF3)-, -CF2-O-CF2CF2-CF(CF3)-, -CF2-O-CF(CF3)-CF(CF3)-, -CF2-O-CF(CF3)CF2-CF(CF3)-, or -CF2-O-CF(CF3)CF2-O-CF(CF3)-.

[0092] The above polymer (I) is also preferably highly fluorinated. For example, anionic groups (A 0 ) such as phosphate group moieties (e.g., CH2OP(O)(OM)2) and sulfate group moieties (e.g., CH2OS(O)2OM)

[0093] except, it is preferable that 80% or more, 90% or more, 95% or more, or 100% of the C-H bonds in the polymer (I) are replaced by C-F bonds.

[0093] The above polymer (I) preferably has C-F bonds and no C-H bonds except for the anionic group (A 0 ). That is, in the general formula (I), X 1 , X 2 , and X 3 are all preferably F, and R is preferably a perfluoroalkylene group having 1 or more carbon atoms. The above perfluoroalkylene group may be either linear or branched, either cyclic or acyclic, and may contain at least one catenary heteroatom. The carbon number of the above perfluoroalkylene group may be 2 to 20, or may be 4 to 18.

[0094] The above polymer (I) may be partially fluorinated. That is, the polymer (I) preferably has at least one hydrogen atom bonded to a carbon atom and at least one fluorine atom bonded to a carbon atom except for the anionic group (A 0 ).

[0095] The above anionic group (A 0It may be -SO3M, -OSO3M, -COOM, -SO2NR’CH2COOM, -CH2OP(O)(OM)2, [-CH2O]2P(O)(OM), -CH2CH2OP(O)(OM)2, [-CH2CH2O]2P(O)(OM), -CH2CH2OSO3M, -P(O)(OM)2, -SO2NR’CH2CH2OP(O)(OM)2, [-SO2NR’CH2CH2O]2P(O)(OM), -CH2OSO3M, -SO2NR’CH2CH2OSO3M, or -C(CF3)2OM. Among them, -SO3M, -COOM or -P(O)(OM)2 is preferred, -SO3M or -COOM is more preferred, and -COOM is even more preferred. Said M is -H, a metal atom, -NR 7 4, an imidazolium which may have a substituent, a pyridinium which may have a substituent or a phosphonium which may have a substituent, and R 7 is H or an organic group. Examples of said metal atom include an alkali metal (Group 1), an alkaline earth metal (Group 2), etc., and Na, K or Li is preferred. Said M is preferably -H, a metal atom or -NR 7 4, more preferably -H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or -NR 7 4, even more preferably -H, -Na, -K, -Li or -NH4, even more preferably -Na, -K or -NH4, particularly preferably -Na or -NH4, and most preferably -NH4. In said polymer (I), each polymer unit (I) may have different anionic groups or the same anionic groups.

[0096] It is also preferred that said polymer (I) is a polymer containing a polymer unit (Ia) based on a monomer represented by the following formula (Ia). CF2=CF-O-Rf 0 -A 0 (Ia) (In the formula, A 0 is an anionic group, and Rf 0is a perfluorinated, divalent linking group which may be linear or branched, cyclic or acyclic, saturated or unsaturated, substituted or unsubstituted, and which optionally further contains one or more heteroatoms selected from the group consisting of sulfur, oxygen, and nitrogen.)

[0097] It is also preferable that the polymer (I) is a polymer containing a polymerization unit (Ib) based on a monomer represented by the following formula (Ib). CH2=CH-O-Rf 0 -A 0 (Ib) (In the formula, A 0 is an anionic group, and Rf 0 is a perfluorinated divalent linking group defined by formula (Ia).)

[0098] In general formula (I), A 0 is preferably in the form of a sulfate group. A 0 is, for example, -CH2OSO3M, -CH2CH2OSO3M, or -SO2NR’CH2CH2OSO3M, where R’ is H or an alkyl group having 1 to 4 carbon atoms, and M is the same as above.) A 0 When A is a sulfate group, examples of the monomer represented by general formula (I) include CF2=CF(OCF2CF2CH2OSO3M), CH2=CH((CF2)4CH2OSO3M), CF2=CF(O(CF2)4CH2OSO3M), CF2=CF(OCF2CF(CF3)CH2OSO3M), CF2=CF(OCF2CF(CF3)OCF2CF2CH2OSO3M), CH2=CH((CF2)4CH2OSO3M), CF2=CF(OCF2CF2SO2N(CH3)CH2CH2OSO3M), CH2=CH(CF2CF2CH2OSO3M), CF2=CF(OCF2CF2CF2CF2SO2N(CH3)CH2CH2OSO3M), CH2=CH(CF2CF2CF2CH2OSO3M), etc. In the above formulas, M is the same as above.)

[0099] In general formula (I), A 0is also a preferred form when it is a sulfonate group. A 0 For example, it is -SO3M, where M is the same as above. A 0 When A is a sulfonate group, examples of the monomer represented by the general formula (I) include CF2=CF(OCF2CF2SO3M), CF2=CF(O(CF2)3SO3M), CF2=CF(O(CF2)4SO3M), CF2=CF(OCF2CF(CF3)SO3M), CF2=CF(OCF2CF(CF3)OCF2CF2SO3M), CH2=CH(CF2CF2SO3M), CF2=CF(OCF2CF(CF3)OCF2CF2CF2CF2SO3M), CH2=CH((CF2)4SO3M), CH2=CH(CF2CF2SO3M), CH2=CH((CF2)3SO3M), etc. In the above formula, M is the same as above.

[0100] In formula (I), A 0 is also a preferred form when it is a carboxylate group. A 0 For example, it is -COOM or -SO2NR’CH2COOM, where R’ is H or an alkyl group having 1 to 4 carbon atoms, and M is the same as above. A 0 When A is a carboxylate group, examples of the monomer represented by the general formula (I) include CF2=CF(OCF2CF2COOM), CF2=CF(O(CF2)3COOM), CF2=CF(O(CF2)4COOM), CF2=CF(O(CF2)5COOM), CF2=CF(OCF2CF(CF3)COOM), CF2=CF(OCF2CF(CF3)O(CF2) nCOOM (n is greater than 1), CH2=CH(CF2CF2COOM), CH2=CH((CF2)4COOM), CH2=CH(CF2CF2COOM), CH2=CH((CF2)3COOM), CF2=CF(OCF2CF2SO2NR’CH2COOM), CF2=CF(O(CF2)4SO2NR’CH2COOM), CF2=CF(OCF2CF(CF3)SO2NR’CH2COOM), CF2=CF(OCF2CF(CF3)OCF2CF2SO2NR’CH2COOM), CH2=CH(CF2CF2SO2NR’CH2COOM), CF2=CF(OCF2CF(CF3)OCF2CF2CF2CF2SO2NR’CH2COOM), CH2=CH((CF2)4SO2NR’CH2COOM), CH2=CH(CF2CF2SO2NR’CH2COOM), CH2=CH((CF2)3SO2NR’CH2COOM), etc. In the above formula, R’ is H or C 1-4 is an alkyl group, and M is the same as above.

[0101] In formula (I), A 0 being a phosphate group is also one of the preferred forms. A 0 For example, -CH2OP(O)(OM)2, [-CH2O]2P(O)(OM), -CH2CH2OP(O)(OM)2, [-CH2CH2O]2P(O)(OM), [-SO2NR’CH2CH2O]2P(O)(OM) or -SO2NR’CH2CH2OP(O)(OM)2, where R’ is an alkyl group having 1 to 4 carbon atoms and M is the same as above. A 0When it is phosphate, examples of the monomer represented by the general formula (I) include CF2=CF(OCF2CF2CH2OP(O)(OM)2), CF2=CF(O(CF2)4CH2OP(O)(OM)2), CF2=CF(OCF2CF(CF3)CH2OP(O)(OM)2), CF2=CF(OCF2CF(CF3)OCF2CF2CH2OP(O)(OM)2), CF2=CF(OCF2CF2SO2N(CH3)CH2CH2OP(O)(OM)2), CF2=CF(OCF2CF2CF2CF2SO2N(CH3)CH2CH2OP(O)(OM)2), CH2=CH(CF2CF2CH2OP(O)(OM)2), CH2=CH((CF2)4CH2OP(O)(OM)2), CH2=CH(CF2CF2CH2OP(O)(OM)2), CH2=CH((CF2)3CH2OP(O)(OM)2), etc. In the above formula, M is the same as defined above.

[0102] In formula (I), A 0 being a phosphonate group is also one of the preferred forms. A 0 When A is a phosphonate group, examples of the monomer represented by the general formula (I) include CF2=CF(OCF2CF2P(O)(OM)2), CF2=CF(O(CF2)4P(O)(OM)2), CF2=CF(OCF2CF(CF3)P(O)(OM)2), CF2=CF(OCF2CF(CF3)OCF2CF2P(O)(OM)2), CH2=CH(CF2CF2P(O)(OM)2), CH2=CH((CF2)4P(O)(OM)2), CH2=CH(CF2CF2P(O)(OM)2), CH2=CH((CF2)3P(O)(OM)2), and in the formula, M is the same as defined above.

[0103] The above polymer (I) is preferably a polymer (1) containing a polymer unit (1) based on the monomer represented by the following general formula (1). CX2=CY(-CZ2-O-Rf-A) (1) (In the formula, X is the same or different and is -H or -F, Y is -H, -F, an alkyl group or a fluorine-containing alkyl group, and Z is the same or different and is -H, -F, an alkyl group or a fluoroalkyl group. Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, or a fluorine-containing alkylene group having an ether bond 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 optionally substituted imidazolium, an optionally substituted pyridinium or an optionally substituted phosphonium, and R 7 is H or an organic group). However, at least one of X, Y and Z contains a fluorine atom.) In addition, the fluorine-containing alkylene group having an ether bond and having 2 to 100 carbon atoms does not include a structure in which an oxygen atom is at the terminal, and is an alkylene group containing an ether bond between carbon atoms.

[0104] In the above general formula (1), X is -H or -F. Both of X may be -F, or at least one of them may be -H. For example, one of them may be -F and the other may be -H, or both of them may be -H.

[0105] In the above general formula (1), Y is -H, -F, an alkyl group or a fluorine-containing alkyl group. The above alkyl group is an alkyl group that does not contain a fluorine atom, and the number of carbon atoms may be 1 or more. The number of carbon atoms of the above alkyl group is preferably 6 or less, more preferably 4 or less, and still more preferably 3 or less. The above fluorine-containing alkyl group is an alkyl group that contains at least one fluorine atom, and the number of carbon atoms may be 1 or more. The number of carbon atoms of the above fluorine-containing alkyl group is preferably 6 or less, more preferably 4 or less, and still more preferably 3 or less. As the above Y, -H, -F or -CF3 is preferable, and -F is more preferable.

[0106] In the above general formula (1), Z is the same or different and is -H, -F, an alkyl group or a fluoroalkyl group. The above alkyl group is an alkyl group that does not contain a fluorine atom, and the number of carbon atoms may be 1 or more. The number of carbon atoms of the above alkyl group is preferably 6 or less, more preferably 4 or less, and still more preferably 3 or less. The above fluorine-containing alkyl group is an alkyl group that contains at least one fluorine atom, and the number of carbon atoms may be 1 or more. The number of carbon atoms of the above fluorine-containing alkyl group is preferably 6 or less, more preferably 4 or less, and still more preferably 3 or less. As the above Z, -H, -F or -CF3 is preferable, and -F is more preferable.

[0107] In the above general formula (1), at least one of the above X, Y and Z contains a fluorine atom. For example, X may be -H, and Y and Z may be -F.

[0108] In the above general formula (1), the above Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, or a fluorine-containing alkylene group having an ether bond and having 2 to 100 carbon atoms. The fluorine-containing alkylene group having 2 to 100 carbon atoms and having an ether bond does not include a structure in which an oxygen atom is at the end, and is an alkylene group containing an ether bond between carbon atoms. The number of carbon atoms of the above fluorine-containing alkylene group is preferably 2 or more. Further, the number of carbon atoms of the above fluorine-containing alkylene group is preferably 30 or less, more preferably 20 or less, and still more preferably 10 or less. Examples of the above fluorine-containing alkylene group include -CF2-, -CH2CF2-, -CF2CF2-, -CF2CH2-, -CF2CF2CH2-, -CF(CF3)-, -CF(CF3)CF2-, -CF(CF3)CH2-, etc. The above fluorine-containing alkylene group is preferably a perfluoroalkylene group.

[0109] The number of carbon atoms of the above fluorine-containing alkylene group having an ether bond is preferably 3 or more. Further, the number of carbon atoms of the above fluorine-containing alkylene group having an ether bond is preferably 60 or less, more preferably 30 or less, and still more preferably 12 or less. For example, the following formula:

Chemical formula

[0110] In the above general formula (1), A is -COOM, -SO3M, -OSO3M or -C(CF3)2OM (M is -H, a metal atom, -NR 7 4, imidazolium which may have a substituent, pyridinium which may have a substituent or phosphonium which may have a substituent, and R 7 is H or an organic group). R 7 is preferably H or an organic group of C 1-10 is more preferably H or an organic group of C 1-4 and is even more preferably H or an alkyl group of C 1-4 . Examples of the above metal atom include alkali metals (Group 1), alkaline earth metals (Group 2), etc., and Na, K or Li is preferable. As the above M, -H, a metal atom or -NR 7 4 is preferable, and -H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or -NR7 4 is more preferable, -H, -Na, -K, -Li or -NH4 is still more preferable, -Na, -K or -NH4 is even more preferable, -Na or -NH4 is particularly preferable, and -NH4 is most preferable. As the above A, -COOM or -SO3M is preferable, and -COOM is more preferable.

[0111] Examples of the monomer represented by the general formula (1) include the following formula (1a): CX2=CFCF2-O-(CF(CF3)CF2O) n5 -CF(CF3)-A (1a) (In the formula, each X is the same and represents F or H. n5 represents 0 or an integer of 1 to 10, and A is the same as defined above.) Fluoroallyl ether compounds represented thereby are preferably exemplified. In the above formula (1a), the above n5 is preferably 0 or an integer of 1 to 5, more preferably 0, 1 or 2, and even more preferably 0 or 1 in terms of obtaining PTFE particles with a small primary particle diameter. The above A is preferably -COOM, and the above M is preferably H or NH4. The above polymer (1) may be a homopolymer of a fluoroallyl ether compound represented by the general formula (1a), or a copolymer with other monomers.

[0112] The above polymerization unit (1) is preferably a polymerization unit (1A) based on a monomer represented by the following general formula (1A). CH2=CF(-CF2-O-Rf-A) (1A) (In the formula, Rf and A are the same as above.) The above polymer (1) may be a homopolymer of a monomer represented by the general formula (1A), or a copolymer with other monomers.

[0113] Specific examples of the monomer represented by the formula (1A) include the following formula

[0114]

Chemical formula

[0115] (wherein, 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 0 to 10; s1 is 0 or 1; t1 is an integer from 0 to 5, provided that when Z 3 and Z 4 are both H, p1 + q1 + r1 + s1 is not 0). Examples of the monomer represented by the formula include

[0116]

Chemical formula

[0117] etc. are preferably mentioned, and among them

[0118]

Chemical formula

[0119] is preferably the case.

[0120] As the monomer represented by the general formula (1A), it is preferable that A in the formula (1A) is -COOM. In particular, at least one selected from the group consisting of CH2 = CFCF2OCF(CF3)COOM and CH2 = CFCF2OCF(CF3)CF2OCF(CF3)COOM (wherein, M is the same as defined above) is preferable, and CH2 = CFCF2OCF(CF3)COOM is more preferable.

[0121] In addition, examples of the monomer represented by the general formula (1) also include monomers represented by the following formula.

[0122] CF2 = CFCF2 - O - Rf - A (wherein, Rf and A are the same as above)

[0123] More specifically, [Chemical formula] etc. can be mentioned.

[0124] The polymer (I) is preferably a polymer (2) containing a polymerization unit (2) based on the monomer represented by the general formula (2). CX2=CY(-O-Rf-A) (2) (In the formula, X is the same or different and is -H or F, Y is -H, -F, an alkyl group or a fluorine-containing alkyl group, Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, or a fluorine-containing alkylene group having an ether bond and having 2 to 100 carbon atoms. A is the same as described above.)

[0125] In the general formula (2), X is -H or -F. Both X may be -F, or at least one of them may be -H. For example, one may be -F and the other may be -H, or both may be -H.

[0126] In the general formula (2), Y is -H, -F, an alkyl group or a fluorine-containing alkyl group. The above alkyl group is an alkyl group that does not contain a fluorine atom, and the number of carbon atoms may be 1 or more. The number of carbon atoms of the above alkyl group is preferably 6 or less, more preferably 4 or less, and still more preferably 3 or less. The above fluorine-containing alkyl group is an alkyl group that contains at least one fluorine atom, and the number of carbon atoms may be 1 or more. The number of carbon atoms of the above fluorine-containing alkyl group is preferably 6 or less, more preferably 4 or less, and still more preferably 3 or less. As Y, -H, -F or -CF3 is preferable, and -F is more preferable.

[0127] In the above general formula (2), at least one of the above X and Y preferably contains a fluorine atom. For example, X may be -H, and Y and Z may be -F.

[0128] In the above general formula (2), the Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having an ether bond and having 2 to 100 carbon atoms. The fluorine-containing alkylene group having an ether bond and having 2 to 100 carbon atoms does not include a structure in which an oxygen atom is at the terminal and is an alkylene group containing an ether bond between carbon-carbon bonds. The number of carbon atoms of the above fluorine-containing alkylene group is preferably 2 or more. Further, it is preferably 30 or less, more preferably 20 or less, and still more preferably 10 or less. Examples of the fluorine-containing alkylene group include -CF2-, -CH2CF2-, -CF2CF2-, -CF2CH2-, -CF2CF2CH2-, -CF(CF3)-, -CF(CF3)CF2-, -CF(CF3)CH2- and the like. The fluorine-containing alkylene group is preferably a perfluoroalkylene group.

[0129] The monomer represented by the general formula (2) is preferably at least one selected from the group consisting of the monomers represented by the general formulas (2a), (2b), (2c), (2d) and (2e). CF2=CF-O-(CF2) n1 -A (2a) (In the formula, n1 represents an integer of 1 to 10, and A is the same as defined above.) CF2=CF-O-(CF2C(CF3)F) n2 -A (2b) (In the formula, n2 represents an integer of 1 to 5, and A is the same as defined above.) CF2=CF-O-(CFX 1 ) n3 -A (2c) (In the formula, X 1 represents F or CF3, n3 represents an integer of 1 to 10, and A is the same as defined above.) CF2=CF-O-(CF2CFX 1 O) n4 -(CF2) n6 -A (2d) (In the formula, n4 represents an integer of 1 to 10, n6 is an integer of 1 to 3, and A and X 1 are the same as defined above.) CF2=CF-O-(CF2CF2CFX1 O) n5 -CF2CF2CF2-A (2e) (In the formula, n5 represents an integer from 0 to 10, and A and X 1 are the same as defined above.)

[0130] In the above formula (2a), n1 is preferably an integer of 5 or less, more preferably an integer of 2 or less.

[0131] Examples of the monomer represented by the above formula (2a) include CF2=CF-O-CF2COOM, CF2=CF(OCF2CF2COOM), and CF2=CF(O(CF2)3COOM) (where M is the same as defined above).

[0132] In the above formula (2b), n2 is preferably an integer of 3 or less in terms of the dispersion stability of the resulting composition.

[0133] In the above formula (2c), n3 is preferably an integer of 5 or less in terms of water solubility, A is preferably -COOM, and M is preferably H or NH4.

[0134] In the above formula (2d), X 1 is preferably -CF3 in terms of dispersion stability, n4 is preferably an integer of 5 or less in terms of water solubility, A is preferably -COOM, and M is preferably H or NH4.

[0135] Examples of the monomer represented by the above formula (2d) include CF2=CFOCF2CF(CF3)OCF2CF2COOM, CF2=CFOCF2CF(CF3)OCF2COOM, and CF2=CFOCF2CF(CF3)OCF2CF2CF2COOM (where M represents H, NH4, or an alkali metal). In the above formula (2e), n5 is preferably an integer of 5 or less in terms of water solubility, A is preferably -COOM, and M is preferably H or NH4. Examples of the monomer represented by the above formula (2e) include CF2=CFOCF2CF2CF2COOM (where M represents H, NH4, or an alkali metal).

[0136] The polymer (I) is preferably a polymer (3) containing a polymerization unit (3) based on the monomer represented by the general formula (3). CX2=CY(-Rf-A) (3) (In the formula, X is the same or different and is -H or -F, Y is -H, -F, an alkyl group, or a fluorinated alkyl group, Rf is a fluorinated alkylene group having 1 to 40 carbon atoms, or a fluorinated alkylene group having an ether bond and 2 to 100 carbon atoms. A is the same as described above.) The fluorinated alkylene group having an ether bond and 2 to 100 carbon atoms does not include a structure with an oxygen atom at the terminal and is an alkylene group containing an ether bond between carbon atoms.

[0137] In the general formula (3), Rf is preferably a fluorinated alkylene group having 1 to 40 carbon atoms. In the general formula (3), at least one of X and Y preferably contains a fluorine atom.

[0138] The monomer represented by the general formula (3) is the general formula (3a): CF2=CF-(CF2) n1 -A (3a) (In the formula, n1 represents an integer from 1 to 10, and A is the same as defined above.), and the general formula (3b): CF2=CF-(CF2C(CF3)F) n2 -A (3b) (In the formula, n2 represents an integer from 1 to 5, and A is the same as defined above.), and at least one selected from the group consisting of monomers represented by the formula is preferred. In the above formula (3a) and the above formula (3b), the above A is preferably -SO3M or -COOM, and M is H, a metal atom, NR 74. It is preferably an optionally substituted imidazolium, an optionally substituted pyridinium or an optionally substituted phosphonium. R 7 represents H or an organic group.

[0139] In the above formula (3a), n1 is preferably an integer of 5 or less, and more preferably an integer of 2 or less. A is preferably -COOM, and M is preferably H or NH4. Examples of the monomer represented by the above formula (3a) include CF2 = CFCF2COOM (where M is as defined above).

[0140] In the above formula (3b), n2 is preferably an integer of 3 or less from the viewpoint of the dispersion stability of the resulting aqueous dispersion, A is preferably -COOM, and M is preferably H or NH4.

[0141] Next, a preferred configuration when m is an integer of 2 or more in the general formula (I) will be described.

[0142] The polymer (I) is also preferably a polymer (4) containing a polymerization unit (4) based on at least one monomer selected from the group consisting of monomers represented by the general formula (4a) and the general formula (4b). CF2 = CF - CF2 - O - Q F1 -CF(-Q F2 -CZ 1 Z 2 -A)2(4a) (wherein Z 1 , Z 2 and A are as defined above, Q F1 and Q F2 are the same or different and are a single bond, a fluorine-containing alkylene group which may contain an ether bond between carbon atoms or a fluorine-containing oxyalkylene group which may contain an ether bond between carbon atoms) CF2 = CF - O - Q F1 -CF(-Q F2 -CZ 1 Z 2-A)2(4b) (wherein Z 1 , Z 2 , A, Q F1 and Q F2 are the same as defined above)

[0143] Examples of the monomers represented by general formula (4a) and general formula (4b) include [Chemical formula] and the like.

[0144] The polymer (I) is preferably at least one selected from the group consisting of polymer (1), polymer (2), and polymer (3), and polymer (1) is more preferable.

[0145] The above polymer (I) may be a homopolymer consisting only of the above polymerization unit (I), or may be a copolymer containing the above polymerization unit (I) and a polymerization unit based on another monomer copolymerizable with the monomer represented by general formula (I). From the viewpoint of solubility in the polymerization medium, a homopolymer consisting only of the polymerization unit (I) is preferable. The polymerization unit (I) may be the same or different at each occurrence, and the polymer (I) may contain polymerization units (I) based on two or more different monomers represented by general formula (I).

[0146] As the above other monomer, a fluorine-containing ethylenic monomer having 2 or 3 carbon atoms is preferable, and examples thereof include CF2=CF2, CF2=CFCl, CH2=CF2, CFH=CH2, CFH=CF2, CF2=CFCF3, CH2=CFCF3, CH2=CHCF3, CHF=CHCF3 (E isomer), CHF=CHCF3 (Z isomer), and the like. Among them, at least one selected from the group consisting of tetrafluoroethylene (CF2=CF2), chlorotrifluoroethylene (CF2=CFCl), and vinylidene fluoride (CH2=CF2) is preferable in terms of good copolymerizability, and tetrafluoroethylene is more preferable. Therefore, the polymerization unit based on the other monomer is preferably a monomer unit (polymerization unit) based on tetrafluoroethylene. The polymerization units based on the other monomer may be the same or different in each occurrence, and the polymer (I) may contain polymerization units based on two or more different other monomers.

[0147] Examples of the other monomer also include the following formula (n1-2):

[0148] [Chemical formula]

[0149] (In the formula, 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 fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having an ether bond and having 2 to 100 carbon atoms).

[0150] Specifically, CH2=CFCF2-O-Rf 3 , CF2=CF-O-Rf 3 , CF2=CFCF2-O-Rf 3 , CF2=CF-Rf 3 , CH2=CH-Rf 3 , CH2=CH-O-Rf 3 (In the formula, Rf 3 is the same as the formula (n1-2)) and the like are preferably exemplified.

[0151] Examples of the other monomer also include the formula (n2-1):

[0152] [Chemical formula]

[0153] (wherein, X 9 is H, F or CH3; Rf 4 is a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having an ether bond and 2 to 100 carbon atoms), and fluorine-containing acrylate monomers represented thereby are also included. The above Rf 4 group is

[0154] [Chemical formula]

[0155] (wherein, d3 is an integer from 1 to 4; e3 is an integer from 1 to 10), etc. are included.

[0156] As the above other monomer, the formula (n2-2): CH2=CHO-Rf 5 (n2-2) (wherein, Rf 5 is a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having an ether bond and 2 to 100 carbon atoms), and fluorine-containing vinyl ethers represented thereby are also included.

[0157] Specific examples of the monomer of the formula (n2-2) include

[0158] [Chemical formula]

[0159] (wherein, e6 is an integer from 1 to 10), etc. are preferably included.

[0160] More specifically,

[0161] [Chemical formula]

[0162] include the like.

[0163] In addition, formula (n2-3): CH2=CHCH2O-Rf 6 (n2-3) (wherein Rf 6 is a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having an ether bond with 2 to 100 carbon atoms) represented by a fluorine-containing allyl ether, formula (n2-4): CH2=CH-Rf 7 (n2-4) (wherein Rf 7 is a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having an ether bond with 2 to 100 carbon atoms) represented by a fluorine-containing vinyl monomer and the like are also included.

[0164] Specific examples of the monomers represented by the above formulas (n2-3) and (n2-4) include

[0165]

Chemical formula

[0166] monomers such as the like.

[0167] The above polymer (I) usually has end groups. The end groups are 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 additionally contain at least one chain heteroatom. The above alkyl group or fluoroalkyl group preferably has 1 to 20 carbon atoms. These end groups generally are generated from an initiator or a chain transfer agent used in the formation of polymer (I), or are generated during a chain transfer reaction.

[0168] The content of polymer (I) is preferably 1.0 mol% or more, more preferably 3.0 mol% or more, still more preferably 5.0 mol% or more, even more preferably 10 mol% or more, particularly preferably 20 mol% or more, and especially preferably 30 mol% or more, based on all polymer units. More preferably, it is 40 mol% or more, still more preferably 60 mol% or more, even more preferably 80 mol% or more, particularly preferably 90 mol% or more, and especially preferably substantially 100 mol%, and most preferably it consists only of polymer unit (I). In polymer (I), the content of polymer units based on other monomers copolymerizable with the monomer represented by general formula (I) is preferably 99.0 mol% or less, more preferably 97.0 mol% or less, still more preferably 95.0 mol% or less, even more preferably 90 mol% or less, particularly preferably 80 mol% or less, and especially preferably 70 mol% or less, based on all polymer units. More preferably, it is 60 mol% or less, still more preferably 40 mol% or less, even more preferably 20 mol% or less, particularly preferably 10 mol% or less, and especially preferably substantially 0 mol%, and most preferably it does not contain polymer units based on other monomers.

[0169] The number average molecular weight of the above polymer (I) is preferably 0.1×10 4 or more, more preferably 0.2×10 4 or more, still more preferably 0.3×10 4 or more, particularly preferably 0.4×10 4 or more, especially preferably 0.5×10 4 or more, particularly preferably 1.0×10 4 or more, especially preferably 3.0×10 4 or more, most preferably 3.1×10 4 or more. Also, it is preferably 75.0×10 4 or less, more preferably 50.0×10 4 or less, still more preferably 40.0×10 4 or less, particularly preferably 30.0×10 4 or less, especially preferably 20.0×10 4The following are particularly preferred. The above number average molecular weight and the weight average molecular weight described below are values obtained by calculating the molecular weight using gel permeation chromatography (GPC) with monodisperse polystyrene as a standard. When measurement by GPC is not possible, the number average molecular weight of polymer (I) can be determined from the correlation between the number average molecular weight calculated from the number of terminal groups obtained by NMR, FT-IR, etc. and the melt flow rate. The melt flow rate can be measured in accordance with JIS K 7210.

[0170] The weight average molecular weight of the above polymer (I) is 0.2×10 4 or more is preferred, 0.4×10 4 or more is more preferred, 0.6×10 4 or more is still more preferred, 0.8×10 4 or more is particularly preferred, 1.0×10 4 or more is even more preferred, 5.0×10 4 or more is even more particularly preferred, 10.0×10 4 or more is still more particularly preferred, 15.0×10 4 or more is even more preferred, 20.0×10 4 or more is even more particularly preferred, 25.0×10 4 or more is most preferred. Also, 150.0×10 4 or less is preferred, 100.0×10 4 or less is more preferred, 60.0×10 4 or less is still more preferred, 50.0×10 4 or less is particularly preferred, 40.0×10 4 or less is particularly preferred.

[0171] Polymer (I) preferably has water solubility. Water solubility means the property of being easily dissolved or dispersed in water. A polymer (I) having water solubility cannot, for example, have its particle size measured by dynamic light scattering (DLS). On the other hand, a polymer (I) having water insolubility can, for example, have its particle size measured by dynamic light scattering (DLS). From the perspective of water solubility, the polymer (I) preferably has an ion exchange ratio (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 group. Precursor groups that become ionic by hydrolysis (e.g., -SO2F) are not regarded as ionic groups for the purpose of determining the IXR. The IXR is preferably 0.5 or more, more preferably 1 or more, still more preferably 3 or more, even more preferably 4 or more, particularly preferably 5 or more, and especially preferably 8 or more. Also, the IXR is more preferably 43 or less, still more preferably 33 or less, and particularly preferably 23 or less. In the polymer (I), the ionic group (anionic group) is typically distributed along the polymer main chain. The above polymer (I) includes the polymer main chain together with the repeating side chains bonded to this main chain, and it is preferable that these side chains have ionic groups. The polymer (I) preferably contains an ionic group having a pKa of less than 10, more preferably less than 7. The ionic groups of the polymer (I) are preferably selected from the group consisting of sulfonate, carboxylate, phosphonate, and phosphate. The terms "sulfonate, carboxylate, phosphonate, and phosphate" are intended to refer to their respective salts or the respective acids capable of forming salts. When a salt is used, preferably, the salt is an alkali metal salt or an ammonium salt. A preferred ionic group is the sulfonate group. The ion exchange capacity of the polymer (I) is preferably, in descending order, 0.80 meg / g or more, 1.50 meg / g or more, 1.75 meg / g or more, 2.00 meg / g or more, 2.50 meg / g or more, 2.60 meg / g or more, 3.00 meg / g or more, 3.50 meg / g or more. The ion exchange capacity is the content of the ionic groups (anionic groups) of the polymer (I) and is determined by calculation from the composition of the polymer (I).

[0172] The above polymer (I) can be produced by a conventionally known method except for using the above monomers. The polymerization of the monomer (I) is preferably carried out substantially in the absence of a fluorine-containing surfactant (excluding the monomer (I) represented by the general formula (I)) described later. "Substantially in the absence of a fluorine-containing surfactant" means that the amount of the fluorine-containing surfactant with respect to the medium used for the polymerization of the monomer (I) is 10 mass ppm or less. The amount of the fluorine-containing surfactant with respect to the medium 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.

[0173] In the water containing the above polymer (I), the content of the polymer (I) is not particularly limited. However, for example, from the viewpoint of enhancing the removal efficiency, it is preferably 10% by mass or less. In the water containing the above polymer (I), the content of the polymer (I) is more preferably 1% by mass or less, still more preferably 0.5% by mass or less, and particularly preferably 0.2% by mass or less. Also, it may be more than 0% by mass, may be more than 0.005% by mass, may be more than 0.006% by mass, may be more than 0.008% by mass, may be 0.010% by mass or more, may be more than 0.020% by mass, may be more than 0.025% by mass, or may be 0.1% by mass or more. The content of the above polymer (I) can be measured by solid NMR. As a method for measuring the content of the above polymer (I), the measurement methods of the respective polymers described in International Publication No. 2014 / 099453, International Publication No. 2010 / 075497, International Publication No. 2010 / 075496, International Publication No. 2011 / 008381, International Publication No. 2009 / 055521, International Publication No. 1987 / 007619, JP-A No. 61-293476, International Publication No. 2010 / 075494, International Publication No. 2010 / 075359, International Publication No. 2012 / 082454, International Publication No. 2006 / 119224, International Publication No. 2013 / 085864, International Publication No. 2012 / 082707, International Publication No. 2012 / 082703, International Publication No. 2012 / 082454, International Publication No. 2012 / 082451, International Publication No. 2006 / 135825, International Publication No. 2004 / 067588, International Publication No. 2009 / 068528, JP-A No. 2004-075978, JP-A No. 2001-226436, International Publication No. 1992 / 017635, International Publication No. 2014 / 069165, JP-A No. 11-181009, etc. are described. The water containing the above polymer (I) may contain one single polymer (I) or may contain two or more different polymers (I).

[0174] The water containing the above polymer (I) may contain substances other than the polymer (I) and water, and may be a dispersion, an aqueous solution, or the like. Examples of the substances other than the polymer (I) and water include non-fluorine polymers other than the polymer (I), fluorine-containing polymers (fluoropolymers) other than the polymer (I), oligomers, and the like. It is also preferable that the non-fluorine polymer and the fluorine-containing polymer other than the polymer (I) do not contain the polymerized unit (I) based on the monomer represented by the general formula (I). As the fluorine-containing polymer other than the polymer (I), a fluorine-containing polymer having an ion exchange rate (IXR) higher than 53 is preferred. The preferred fluorine-containing polymer other than the polymer (I) has no ionic groups or has a limited number of ionic groups that result in an ion exchange rate higher than about 100. The ion exchange rate of the preferred fluorine-containing polymer other than the polymer (I) is preferably 1000 or more, more preferably 2000 or more, and still more preferably 5000 or more. Examples of the fluorine-containing polymer other than the above polymer (I) include PTFE, copolymers of TFE and another monomer copolymerizable with TFE (fluorine-containing monomers such as vinylidene fluoride, hexafluoropropylene, chlorotrifluoroethylene, perfluoro(alkyl vinyl ether), etc., hydrocarbon olefins such as ethylene, propylene, isobutene, etc., alkyl vinyl ether, etc.) (for example, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), etc.), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), and fluororesins such as ethylene-chlorotrifluoroethylene (ECTFE), vinylidene fluoride-based rubbers (FKM) such as vinylidene fluoride-hexafluoropropylene copolymer, fluorine rubbers such as tetrafluoroethylene-propylene rubber (FEPM) and tetrafluoroethylene-perfluoromethyl vinyl ether rubber (FFKM), and fluorine-containing elastomers, etc. The above PTFE may be a homopolymer of TFE or a modified PTFE containing 99.0% by mass or more of TFE and 1.0% by weight or less of a modifying monomer. As the above fluorine-containing polymer, at least one selected from the group consisting of PTFE and a melt-processable fluororesin containing 60.0 to 98.0% by mass of TFE units and 2.0 to 40.0% by mass of other monomers is preferred, and PTFE is more preferred. The water containing the polymer (I) may contain the polymer (I) and a fluorine-containing polymer other than the polymer (I), and it is more preferable to contain the polymer (I) and at least one selected from the group consisting of PTFE and a melt-processable fluororesin containing 60.0 to 98.0% by mass of TFE units and 2.0 to 40.0% by mass of other monomers. It is even more preferable to contain the polymer (I) and PTFE.

[0175] In the water containing the polymer (I), the content of substances other than the polymer (I) and water is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.2% by mass or less. The lower limit of the content of substances other than the polymer (I) and water is not limited, and for example, it may be 0% by mass or 0.1% by mass.

[0176] In the water containing the polymer (I), the water content is preferably 99.0% by mass or more. More preferably, it is 99.5% by mass or more, and even more preferably 99.8% by mass or more.

[0177] The pH of the water containing the polymer (I) to be subjected to the above removal step (before the removal step, for example, the water containing the polymer (I) before adding the above inorganic flocculant) may be, for example, 1.5 to 13.5 or 2 to 13. The pH of the water containing the polymer (I) can be adjusted with a pH adjuster. The pH adjuster is not limited, and for example, the acid compounds, alkali compounds, etc. described above can be used.

[0178] The water containing the polymer (I) is not particularly limited as long as it contains the polymer (I), and may be, for example, water (wastewater) generated in industrial production. It is also one of the preferred embodiments of the present disclosure that the water containing the polymer (I) is wastewater. The removal method of the present disclosure is effective, for example, in treating the water generated in the polymer production process described later, and particularly effective in treating the water that has undergone the polymerization process. Therefore, it is also one of the preferred embodiments of the present disclosure that the water containing the polymer (I) is the water generated in the polymer production process. The water containing the polymer (I) is preferably the water that has undergone the polymerization process, and more preferably the water that has undergone the polymerization process of a fluorine-containing polymer (fluoropolymer). The polymerization process may be, for example, a process of polymerizing a monomer (for example, the following fluorine-containing monomer) in an aqueous medium in the presence of the polymer (I). The above aqueous medium is a reaction medium for carrying out polymerization and means a liquid containing water. The aqueous medium is not particularly limited as long as it contains water, and may contain water and, for example, a fluorine-free organic solvent such as alcohol, ether, ketone, and / or a fluorine-containing organic solvent having a boiling point of 40°C or lower.

[0179] Examples of the water generated in the polymer production process include, in addition to the water that has undergone the polymerization process of polymerizing one or more monomers, the water generated in the pretreatment process before the polymerization process (for example, the process of preparing an emulsifier of a predetermined concentration), and the water generated in the post-treatment process after the polymerization process (for example, the concentration process of the aqueous dispersion, the solid-liquid separation process, the coagulation process, the washing process, the dehydration process, the drying process, the heat treatment process, etc.). Examples of the water that has undergone the polymerization process include the water generated in the polymer production process, particularly the fluorine-containing polymer production process described later. As the water containing the polymer (I), for example, the water generated in the polymer production process may be used as it is, or the water generated in the polymer production process may be diluted or concentrated and used. The water containing the polymer (I) includes an aqueous solution, a dispersion, and a liquid obtained by liquefying a gas (such as the exhaust gas generated in the drying process described later). Hereinafter, the fluoropolymer production process will be described as an example. However, the water that has undergone the above polymerization process includes not only the water generated in the fluoropolymer production process, but also the water generated in any polymer production process.

[0180] In this specification, the "fluoropolymer production process" means the entire process of polymerizing one or more monomers including a fluoromonomer to produce a fluoropolymer, and is not limited to a specific production process. The fluoropolymer can also be produced by polymerizing a fluoromonomer in the presence of a polymer (I). The water containing the above polymer (I) preferably includes the water obtained in the fluoropolymer production process using the polymer (I).

[0181] In this specification, the "fluoromonomer" is not particularly limited as long as it is a monomer having at least one fluorine or fluoroalkyl group. For example, trifluoroethylene, tetrafluoroethylene (TFE), vinylidene fluoride (VdF), vinyl fluoride (VF), chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), hexafluoroisobutylene, perfluoroalkyl ethylene, and fluorovinyl ether (FVE), CH2 = CFCF3, CHF = CHCF3 (E isomer), CHF = CHCF3 (Z isomer), etc. may be included. The fluoromonomer is preferably a monomer other than the monomer represented by the general formula (I).

[0182] In this specification, the "fluoropolymer" (fluoropolymer) may be obtained by polymerizing a monomer containing one or more of the above-described fluoromonomers, and may be, for example, a fluoropolymer exemplified as a substance other than the polymer (I) and water, but is not limited thereto. In the first treatment method of the present disclosure, the fluoropolymer may be PTFE. The above PTFE may be a TFE homopolymer or a modified PTFE containing TFE units and modified monomer units based on a modified monomer copolymerizable with TFE. Further, it may be high molecular weight PTFE or low molecular weight PTFE. High molecular weight PTFE usually has non-melt processability and fibrillability. For example, the standard specific gravity (SSG) is 2.130 to 2.280. The above standard specific gravity is measured by the water displacement method in accordance with ASTM D-792 using a sample molded in accordance with ASTM D4895-89. In the present disclosure, "high molecular weight PTFE" means that the standard specific gravity is within the above range.

[0183] The first treatment method of the present disclosure may include the following fluoropolymer production process. In this specification, the "fluoropolymer production process" is not particularly limited as long as it is a process included in the production process of the fluoropolymer, and may include one or more processes constituting a known fluoropolymer production process. The "fluoropolymer production process" may include, in addition to a polymerization process of polymerizing one or more monomers containing a fluoromonomer, a pretreatment process before the polymerization process (for example, a process of preparing an emulsifier having a predetermined concentration, etc.) and a post-treatment process after the polymerization process (for example, a concentration process of an aqueous dispersion, a solid-liquid separation process, a coagulation process, a washing process, a dehydration process, a drying process, a heat treatment process, etc.). Hereinafter, specific examples of the "fluoropolymer production process" will be described, but the method according to the present embodiment is not limited to the following specific examples.

[0184] As described above, the fluoropolymer is produced by polymerizing one or more monomers containing a fluoromonomer. In this polymerization process, it is preferable to polymerize the monomers in an aqueous medium, whereby an aqueous dispersion in which polymer particles are dispersed in the aqueous medium is obtained. The above polymerization process is preferably carried out in the presence of polymer (I). The water containing polymer (I) may be obtained by polymerization using polymer (I). When used in the form of an aqueous dispersion, the obtained aqueous dispersion may be concentrated by a concentration process (for example, phase separation concentration, electroconcentration, filtration using an ultrafiltration membrane, filtration using a reverse osmosis membrane (RO membrane), nanofiltration, etc.). In that case, the liquid containing the polymer (I) remaining after recovering the concentrated aqueous dispersion may be included in the "water containing the polymer (I)" in this specification. After the polymerization step, in the coagulation step, it is preferable to add a salt or an acid to the aqueous dispersion to aggregate the fluorine-containing polymer. Then, in the solid-liquid separation step, it is preferable to separate and recover the aggregated fluorine-containing polymer. The liquid containing the polymer (I) remaining after separating and recovering the fluorine-containing polymer may be included in the "water containing the polymer (I)" in this specification.

[0185] The fluorine-containing polymer separated and recovered in the solid-liquid separation step may be washed with a washing liquid such as an aqueous medium in the washing step. The waste water containing the polymer (I) generated in the washing step may be included in the "water containing the polymer (I)" in this specification. The washing liquid containing the polymer (I) used in the washing step may be included in the "water containing the polymer (I)" in this specification. The fluorine-containing polymer separated and recovered in the solid-liquid separation step may be mechanically dehydrated in the dehydration step. The liquid containing the polymer (I) removed from the fluorine-containing polymer in the dehydration step may be included in the "water containing the polymer (I)" in this specification. The dehydrated fluorine-containing polymer may be washed with a washing liquid, and the waste water containing the polymer (I) generated in this washing step may be included in the "water containing the polymer (I)" in this specification. The washing liquid containing the polymer (I) used in this washing step may also be included in the "water containing the polymer (I)" in this specification.

[0186] The fluorine-containing polymer obtained after the above-mentioned washing step and / or dehydration step may be heated and dried in the drying step to remove the remaining moisture and organic solvent as exhaust gas. The liquid containing the polymer (I) obtained by liquefying the exhaust gas generated in the drying step may be included in the "water containing the polymer (I)" in this specification. The exhaust gas generated in the drying process may contain, in addition to water vapor and organic solvents, the polymer (I) entrained with the fluoropolymer. Therefore, it is preferable to wash this exhaust gas with a cleaning liquid such as water or an aqueous alkali solution. The cleaning liquid containing the polymer (I) used for washing the exhaust gas may also be included in the "water containing the polymer (I)" in this specification.

[0187] The fluoropolymer obtained after the drying process may be formed into a desired shape such as pellets in the heat treatment process. The liquid containing the polymer (I) obtained by liquefying the exhaust gas generated in the heat treatment process may be included in the "water containing the polymer (I)" in this specification. The exhaust gas generated in the heat treatment process may contain the polymer (I) entrained with the fluoropolymer. Therefore, it is preferable to wash this exhaust gas with a cleaning liquid such as water or an aqueous alkali solution. The waste water containing the polymer (I) generated by washing this exhaust gas may be included in the "water containing the polymer (I)" in this specification. The cleaning liquid containing the polymer (I) used for washing the exhaust gas may also be included in the "water containing the polymer (I)" in this specification.

[0188] Note that both the exhaust gas generated in the drying process and the exhaust gas generated in the heat treatment process may be washed together to obtain a single cleaning liquid. The waste water (water) containing the polymer (I) generated by washing both the exhaust gas generated in the drying process and the exhaust gas generated in the heat treatment process together may be included in the "water containing the polymer (I)" in this specification.

[0189] The water containing the polymer (I) may be water generated from the manufacturing process of one type of fluorine-containing polymer, or may contain water generated from the manufacturing processes of a plurality of different types of fluorine-containing polymers. For example, the water containing the polymer (I) may be a mixture containing water generated from the manufacturing process of fluororubber and water generated from the manufacturing process of PTFE (such as low molecular weight PTFE), and according to the first treatment method of the present disclosure, water generated from the manufacturing processes of two types of fluorine-containing polymers can be treated simultaneously. Further, the water containing the polymer (I) may be water generated from one of the processes included in the manufacturing process of the fluorine-containing polymer, or may contain water generated from a plurality of different processes. For example, the water containing the polymer (I) may be a mixture of the water obtained in the fluorine-containing polymer manufacturing process using the polymer (I) and the water obtained in the fluorine-containing polymer manufacturing process using a fluorine-containing surfactant. Further, it may be a mixture of the water obtained in the fluorine-containing polymer manufacturing process using the polymer (I) and the water obtained in the fluorine-containing polymer manufacturing process using a hydrocarbon-based surfactant. The hydrocarbon-based surfactant is not limited, and may be a surfactant having a hydrophilic part and a hydrophobic part on the same molecule. These may be cationic, nonionic or anionic. For example, as the anionic hydrocarbon-based surfactant, R-L-M (wherein R is a linear or branched alkyl group having 1 or more carbon atoms which may have a substituent, or a cyclic alkyl group having 3 or more carbon atoms which may have a substituent, and when the carbon number is 3 or more, it may contain a monovalent or divalent heterocyclic ring or may form a ring. L is -ArSO3 - , -SO3 - , -SO4-, -PO3 - or COO - and M is H, a metal atom, NR 5 4, an imidazolium which may have a substituent, a pyridinium which may have a substituent or a phosphonium which may have a substituent, R 5 is H or an organic group, -ArSO3 -is an aryl sulfonate. An anionic surfactant represented by ) is also included. Specifically, those represented by CH3-(CH2) n -L-M (where n is an integer from 6 to 17. L and M are the same as above) are included. A mixture in which R is an alkyl group having 12 to 16 carbon atoms and L-M is a sulfate can also be used. As the anionic hydrocarbon surfactant, R 6 (-L-M)2 (where R 6 is a linear or branched alkylene group having 1 or more carbon atoms which may have a substituent, or a cyclic alkylene group having 3 or more carbon atoms which may have a substituent. When the carbon number is 3 or more, it may contain a monovalent or divalent heterocyclic ring or may form a ring. L is -ArSO3 - , -SO3 - , -SO4-, -PO3 - or COO - and M is H, a metal atom, NR 5 4, an imidazolium which may have a substituent, a pyridinium which may have a substituent or a phosphonium which may have a substituent, R 5 is H or an organic group, -ArSO3 - is an aryl sulfonate. An anionic surfactant represented by ) is also included. Also, as the anionic hydrocarbon surfactant, R 7 (-L-M)3 (where R 7 is a linear or branched alkylidine group having 1 or more carbon atoms which may have a substituent, or a cyclic alkylidine group having 3 or more carbon atoms which may have a substituent. When the carbon number is 3 or more, it may contain a monovalent or divalent heterocyclic ring or may form a ring. L is -ArSO3 - , -SO3 - , -SO4-, -PO3 - or COO - and M is H, a metal atom, NR 54. An imidazolium which may have a substituent, a pyridinium which may have a substituent or a phosphonium which may have a substituent, R 5 is H or an organic group. -ArSO3 - is an arylsulfonate. ) The anionic surfactant represented by is also included. Examples of the anionic hydrocarbon surfactant include Versatic (registered trademark) 10 of Resolution Performance Products, Avanel S series (S-70, S-74, etc.) manufactured by BASF.

[0190] In addition, the anionic hydrocarbon surfactant also includes a siloxane hydrocarbon surfactant. Examples of the siloxane hydrocarbon surfactant include those described in Silicone Surfactants, R.M. Hill, Marcel Dekker, Inc., ISBN: 0-8247-00104. The structure of the siloxane hydrocarbon surfactant includes a distinct hydrophobic part and a hydrophilic part. The hydrophobic part includes one or more dihydrocarbylsiloxane units, where the substituents on the silicone atom are completely hydrocarbons. In the sense that when the carbon atoms of the hydrocarbyl group can be substituted by a halogen such as fluorine and are completely substituted by hydrogen atoms, these siloxane surfactants can also be regarded as hydrocarbon surfactants, that is, the monovalent substituents on the carbon atoms of the hydrocarbyl group are hydrogen.

[0191] The hydrophilic portion of the siloxane hydrocarbon surfactant may include one or more polar moieties containing ionic groups such as sulfate, sulfonate, phosphonate, phosphate ester, carboxylate, carbonate, sulfosuccinate, taurate (as free acid, salt or ester), phosphine oxide, betaine, betaine copolyol, quaternary ammonium salt, etc. The ionic hydrophobic portion may also include an ionically functionalized siloxane graft. Examples of such siloxane hydrocarbon surfactants include polydimethylsiloxane-graft-(meth)acrylate, polydimethylsiloxane-graft-polyacrylate salt, and polydimethylsiloxane-grafted quaternary amine. The polar moiety of the hydrophilic portion of the siloxane hydrocarbon surfactant may include polyethers such as polyethylene oxide (PEO) and mixed polyethylene oxide / propylene oxide polyethers (PEO / PPO); monosaccharides and disaccharides; and nonionic groups formed by water-soluble heterocycles such as pyrrolidinone. The ratio of ethylene oxide to propylene oxide (EO / PO) can be varied in the mixed polyethylene oxide / propylene oxide polyether.

[0192] The hydrophilic portion of the siloxane hydrocarbon surfactant may also include a combination of ionic and nonionic moieties. Examples of such moieties include ionically end-functionalized or randomly functionalized polyethers or polyols. Preferably, it is a siloxane having a nonionic moiety, i.e., a nonionic siloxane surfactant.

[0193] The arrangement of the hydrophobic and hydrophilic portions of the structure of the siloxane hydrocarbon surfactant may take the form of a diblock polymer (AB), a triblock polymer (ABA) (where "B" represents the siloxane portion of the molecule), or a multiblock polymer. Alternatively, the siloxane surfactant may include a graft polymer.

[0194] The siloxane hydrocarbon surfactant is also disclosed in U.S. Patent No. 6,841,616.

[0195] Examples of the siloxane-based anionic hydrocarbon surfactant include SilSense TM PE-100 silicone, SilSense TM CA-1 silicone, etc.

[0196] Examples of the anionic hydrocarbon surfactant also include the sulfosuccinate surfactant Lankropol® K8300 of Akzo Nobel Surface Chemistry LLC, etc. Examples of the sulfosuccinate surfactant include sodium diisodecyl sulfosuccinate, (Emulsogen® SB10 of Clariant), sodium diisotridecyl sulfosuccinate (Polirol® TR / LNA of Cesapinia Chemicals), etc.

[0197] Examples of the anionic hydrocarbon surfactant also include the PolyFox® surfactant (PolyFox TM PF-156A, PolyFox TM PF-136A, etc.) of Omnova Solutions, Inc.

[0198] Examples of the anionic hydrocarbon surfactant include, for example, the general formula (α): R 10 -COOM (α) (wherein R 10 is a monovalent organic group containing one or more carbon atoms. M is H, a metal atom, NR 11 4, an optionally substituted imidazolium, an optionally substituted pyridinium or an optionally substituted phosphonium, and R 11is H or an organic group, which may be the same or different. Examples thereof include the compound (α) represented by ). R 11 is preferably H or C 1-10 organic group, more preferably H or C 1-4 organic group. From the viewpoint of surface activity, R 10 preferably has 2 or more carbon atoms, more preferably 3 or more carbon atoms. From the viewpoint of water solubility, R 10 preferably has 29 or less carbon atoms, more preferably 23 or less carbon atoms. Examples of the metal atom of M include alkali metals (Group 1), alkaline earth metals (Group 2), etc., and Na, K or Li is preferable. M is preferably H, a metal atom or NR 11 4, more preferably H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or NR 11 4, still more preferably H, Na, K, Li or NH4, still more preferably Na, K or NH4, particularly preferably Na or NH4, and most preferably NH4.

[0199] Examples of the compound (α) include R 12 -COOM (wherein R 12 is a linear or branched alkyl group, alkenyl group, alkylene group or alkenylene group having 1 or more carbon atoms which may have a substituent, or a cyclic alkyl group, alkenyl group, alkylene group or alkenylene group having 3 or more carbon atoms which may have a substituent, and these may contain an ether bond. When the carbon number is 3 or more, it may contain a monovalent or divalent heterocyclic ring or may form a ring. M is the same as above.). Examples thereof also include an anionic surfactant represented by ). Specifically, CH3-(CH2) n -COOM (wherein n is an integer of 2 to 28. M is the same as above).

[0200] From the perspective of emulsion stability, compound (α) may not contain a carbonyl group (excluding the carbonyl group in the carboxyl group). Examples of the hydrocarbon-containing surfactant that does not contain the above carbonyl group include, for example, the following formula (A): R-COO-M (A) (wherein R is an alkyl group, alkenyl group, alkylene group or alkenylene group containing 6 to 17 carbon atoms, and these may contain an ether bond. M is H, a metal atom, NR 11 4, an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. R 11 is, the same or different, H or an organic group having 1 to 10 carbon atoms). Compounds of the above formula (A) are preferably exemplified. In the above formula (A), R is preferably an alkyl group or an alkenyl group (these may contain an ether group). The alkyl group or alkenyl group in the above R may be linear or branched. The number of carbon atoms in the above R is not limited, but is, for example, 2 to 29.

[0201] In the above formula (A), when R is a linear alkyl group, the number of carbon atoms in R is preferably 3 to 29, and more preferably 5 to 23. When the alkyl group is branched, the number of carbon atoms in R is preferably 5 to 35, and more preferably 11 to 23. When the alkenyl group is linear, the number of carbon atoms in R is preferably 2 to 29, and more preferably 9 to 23. When the alkenyl group is branched, the number of carbon atoms in R is preferably 2 to 29, and more preferably 9 to 23.

[0202] Examples of the alkyl group and alkenyl group include, for example, a methyl group, an ethyl group, an isobutyl group, a t-butyl group, a vinyl group and the like.

[0203] In addition, examples of anionic hydrocarbon surfactants include carboxylic acid type hydrocarbon surfactants. Examples of carboxylic acid type hydrocarbon surfactants include, for example, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, palmitoleic acid, margaric acid, stearic acid, oleic acid, vaccenic acid, linoleic acid, (9,12,15)-linolenic acid, (6,9,12)linolenic acid, eleostearic acid, arachidic acid, 8,11-eicosadienoic acid, mead acid, arachidonic acid, behenic acid, lignoceric acid, nervonic acid, cerotic acid, montanic acid, melissic acid, crotonic acid, myristoleic acid, palmitoleic acid, sapienic acid, oleic acid, elaidic acid, vaccenic acid, gadoleic acid, eicosenoic acid, erucic acid, nervonic acid, linoleic acid, eicosadienoic acid, docosadienoic acid, linolenic acid, pinolenic acid, α-eleostearic acid, β-eleostearic acid, mead acid, dihomo-γ-linolenic acid, eicosatrienoic acid, stearidonic acid, arachidonic acid, eicosatetraenoic acid, adrenic acid, bosseopentaenoic acid, eicosapentaenoic acid, osbond acid, sardine acid, tetracosapentaenoic acid, docosahexaenoic acid, nisinic acid, and salts thereof. In particular, at least one selected from the group consisting of lauric acid, capric acid, myristic acid, pentadecylic acid, palmitic acid, and salts thereof is preferable. Examples of the above salts include those in which the hydrogen of the carboxyl group is a metal atom of the above-described formula M, NR 11 4, an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, but is not particularly limited.

[0204] In addition, as the anionic hydrocarbon surfactant, for example, the anionic hydrocarbon surfactants described in International Publication No. 2013 / 146950 and International Publication No. 2013 / 146947 can be used. For example, those having a saturated or unsaturated aliphatic chain with 6 to 40 carbon atoms, preferably 8 to 20 carbon atoms, and more preferably 9 to 13 carbon atoms can be mentioned. The above-mentioned saturated or unsaturated aliphatic chain may be either a straight chain or a branched chain, and may have a cyclic structure. The above-mentioned hydrocarbon may be aromatic or may have an aromatic group. The above-mentioned hydrocarbon may have heteroatoms such as oxygen, nitrogen, and sulfur.

[0205] Examples of the anionic hydrocarbon surfactant include alkyl sulfonates, alkyl sulfates, alkyl aryl sulfates and their salts; aliphatic (carboxylic) acids and their salts; alkyl phosphate esters, alkyl aryl phosphate esters or their salts; etc. Among them, alkyl sulfonates, alkyl sulfates, aliphatic carboxylic acids or their salts are preferred.

[0206] As the alkyl sulfate or its salt, ammonium lauryl sulfate and sodium lauryl sulfate are preferred. As the aliphatic carboxylic acid or its salt, succinic acid, decanoic acid, undecanoic acid, undecenoic acid, lauric acid, hydrododecanoic acid, or their salts are preferred.

[0207] Examples of the above-mentioned fluorine-containing surfactant include anionic fluorine-containing surfactants. The above-mentioned anionic fluorine-containing surfactant may be, for example, a surfactant containing fluorine atoms with a total carbon number of 20 or less in the part excluding the anionic group.

[0208] The above-mentioned fluorine-containing surfactant may also be a surfactant containing fluorine with a molecular weight of the anionic part of 800 or less. Incidentally, the above "anionic moiety" means the moiety excluding the cation of the above fluorine-containing surfactant. For example, in the case of F(CF2) n1 COOM represented by the formula (IA) described later, it is the moiety of "F(CF2) n1 COO".

[0209] Examples of the above fluorine-containing surfactant also include fluorine-containing surfactants having a LogPOW of 3.5 or less. The above LogPOW is the partition coefficient between 1-octanol and water, and is represented by LogP [where P represents the ratio of the concentration of the fluorine-containing surfactant in octanol to the concentration of the fluorine-containing surfactant in water when an octanol / water (1:1) mixed solution containing the fluorine-containing surfactant is phase-separated]. The above LogPOW is determined by performing HPLC on standard substances (heptanoic acid, octanoic acid, nonanoic acid, and decanoic acid) having a known octanol / water partition coefficient under the conditions of column; TOSOH ODS-120T column (φ4.6 mm × 250 mm, manufactured by Tosoh Corporation), eluent; acetonitrile / 0.6 mass% HClO4 water = 1 / 1 (vol / vol%), flow rate; 1.0 ml / min, sample volume; 300 μL, column temperature; 40°C, detection light; UV210 nm, creating a calibration curve between each elution time and the known octanol / water partition coefficient, and calculating from the elution time of HPLC in the sample solution based on this calibration curve.

[0210] Specific examples of the fluorosurfactant include those described in U.S. Patent Application Publication No. 2007 / 0015864, U.S. Patent Application Publication No. 2007 / 0015865, U.S. Patent Application Publication No. 2007 / 0015866, U.S. Patent Application Publication No. 2007 / 0276103, U.S. Patent Application Publication No. 2007 / 0117914, U.S. Patent Application Publication No. 2007 / 142541, U.S. Patent Application Publication No. 2008 / 0015319, U.S. Patent No. 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, International Publication 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, and the like.

[0211] Examples of the anionic fluorosurfactant include the following general formula (N 0 ): X n0 -Rf n0 -Y 0 (N 0 ) (In the formula, X n0 is H, Cl, or and F. Rf n0 is an alkylene group having 3 to 20 carbon atoms, which is linear, branched, or cyclic, and in which some or all of the H atoms are substituted by F atoms. The alkylene group may contain one or more ether bonds, and some of the H atoms may be substituted by Cl atoms. Y 0 is an anionic group.) Compounds represented by this formula are included. Y 0 The anionic group of Y may be -COOM, -SO2M, -SO3M, or -C(CF3)2OM, and may be -COOM or -SO3M. 7 M is H, a metal atom, NR 7is H or an organic group. Examples of the metal atom include alkali metals (Group 1) and alkaline earth metals (Group 2), such as Na, K, or Li. R 7 may be H or an organic group of C 1-10 may be H or an organic group of C 1-4 may be H or an organic group of C 1-4 and may be an alkyl group of C. M may be H, a metal atom, or NR 7 4, may be H, an alkali metal (Group 1), an alkaline earth metal (Group 2), or NR 7 4, and may be H, Na, K, Li, or NH4. The above Rf n0 may have 50% or more of H substituted with fluorine.

[0212] Examples of the compound represented by the general formula (N 0 ) include the following general formula (N 1 ): X n0 -(CF2) m1 -Y 0 (N 1 ) (In the formula, X n0 is H, Cl, or F, m1 is an integer of 3 to 15, and Y 0 is as defined above.) The compound represented by the formula, the following general formula (N 2 ): Rf n1 -O-(CF(CF3)CF2O) m2 CFX n1 -Y 0 (N 2 ) (In the formula, Rf n1 is a perfluoroalkyl group having 1 to 5 carbon atoms, m2 is an integer of 0 to 3, X n1 is F or CF3, and Y 0 is as defined above.) The compound represented by the formula, the following general formula (N 3 ): Rf n2 (CH2) m3 -(Rfn3 ) q -Y 0 (N 3 ) (wherein, Rf n2 is a partially or fully fluorinated alkyl group which may contain an ether bond having 1 to 13 carbon atoms, m3 is an integer of 1 to 3, and Rf n3 is a linear or branched perfluoroalkylene group having 1 to 3 carbon atoms, q is 0 or 1, and Y 0 is as defined above.) A compound represented by the following general formula (N 4 ): Rf n4 -O-(CY n1 Y n2 ) p CF2-Y 0 (N 4 ) (wherein, Rf n4 is a linear or branched partially or fully fluorinated alkyl group which may contain an ether bond having 1 to 12 carbon atoms, Y n1 and Y n2 are the same or different and are H or F, p is 0 or 1, and Y 0 is as defined above.) A compound represented by the formula, and the general formula (N 5 ): [Chemical formula] (wherein, 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 which may contain an ether bond having 1 to 6 carbon atoms. Rf n5 is a linear or branched partially or fully fluorinated alkylene group which may contain an ether bond having 1 to 3 carbon atoms, L is a linking group, and Y 0 is as defined above. However, the total number of carbon atoms of X n2 , X n3 , X n4 and Rf n5 is 18 or less.) Compounds represented by the formula are exemplified.

[0213] As the compound represented by the above general formula (N 0 ), more specifically, perfluorocarboxylic acid (IA) represented by the following general formula (IA), ω-H perfluorocarboxylic acid (II) represented by the following general formula (II), perfluoropolyether carboxylic acid (III) represented by the following general formula (III), perfluoroalkyl alkylene 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), perfluoroalkyl alkylene sulfonic acid (VIII) represented by the following general formula (VIII), alkyl alkylene 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. can be mentioned.

[0214] The above perfluorocarboxylic acid (IA) is represented by the following general formula (IA) F(CF2) n1 COOM (IA) (In the formula, n1 is an integer from 3 to 14, and M is H, a metal atom, NR 7 4, imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent, and R 7 is H or an organic group.)

[0215] The above ω-H perfluorocarboxylic acid (II) is represented by the following general formula (II) H(CF2) n2 COOM (II) (In the formula, n2 is an integer from 4 to 15, and M is as defined above.)

[0216] The above perfluoropolyether carboxylic acid (III) is represented by the following general formula (III) Rf 1 -O-(CF(CF3)CF2O) n3 CF(CF3)COOM (III) (In the formula, Rf 1 is a perfluoroalkyl group having 1 to 5 carbon atoms, n3 is an integer of 0 to 3, and M is as defined above.)

[0217] The above perfluoroalkylalkylene carboxylic acid (IV) is represented by the following general formula (IV) Rf 2 (CH2) n4 Rf 3 COOM (IV) (In the formula, Rf 2 is a perfluoroalkyl group having 1 to 5 carbon atoms, Rf 3 is a linear or branched perfluoroalkylene group having 1 to 3 carbon atoms, n4 is an integer of 1 to 3, and M is as defined above.)

[0218] The above alkoxyfluorocarboxylic acid (V) is represented by the following general formula (V) Rf 4 -O-CY 1 Y 2 CF2-COOM (V) (In the formula, Rf 4 is a linear or branched or completely fluorinated alkyl group which may contain an ether bond having 1 to 12 carbon atoms, Y 1 and Y 2 are the same or different and are H or F, and M is as defined above.)

[0219] The above perfluoroalkylsulfonic acid (VI) is represented by the following general formula (VI) F(CF2) n5 SO3M (VI) (In the formula, n5 is an integer of 3 to 14, and M is as defined above.)

[0220] The above ω-H perfluorosulfonic acid (VII) is represented by the following general formula (VII) H(CF2) n6 SO3M (VII) (wherein n6 is an integer from 4 to 14, and M is as defined above.)

[0221] The above perfluoroalkylalkylene sulfonic acid (VIII) is represented by the following general formula (VIII) Rf 5 (CH2) n7 SO3M (VIII) (wherein Rf 5 is a perfluoroalkyl group having 1 to 13 carbon atoms, n7 is an integer from 1 to 3, and M is as defined above.)

[0222] The above alkylalkylene carboxylic acid (IX) is represented by the following general formula (IX) Rf 6 (CH2) n8 COOM (IX) (wherein Rf 6 is a linear or branched or fully fluorinated alkyl group which may contain an ether bond having 1 to 13 carbon atoms, n8 is an integer from 1 to 3, and M is as defined above.)

[0223] The above fluorocarboxylic acid (X) is represented by the following general formula (X) Rf 7 -O-Rf 8 -O-CF2-COOM (X) (wherein Rf 7 is a linear or branched or fully fluorinated alkyl group which may contain an ether bond having 1 to 6 carbon atoms, Rf 8 is a linear or branched or fully fluorinated alkyl group having 1 to 6 carbon atoms, and M is as defined above.)

[0224] The above alkoxyfluorosulfonic acid (XI) is represented by the following general formula (XI) Rf 9 -O-CY 1 Y 2 CF2-SO3M (XI) (wherein Rf 9 is a linear or branched, partially or fully fluorinated alkyl group which may contain an ether bond having 1 to 12 carbon atoms and may contain chlorine, and Y 1 and Y 2 are the same or different and are H or F, and M is as defined above.)

[0225] The above compound (XII) is represented by the following general formula (XII):

Chemical formula

[0226] The above compound (XIII) is represented by the following general formula (XIII): Rf 11 -O-(CF2CF(CF3)O) n9 (CF2O) n10 CF2COOM (XIII) (wherein Rf 11is a fluoroalkyl group having 1 to 5 carbon atoms and containing chlorine, n9 is an integer from 0 to 3, n10 is an integer from 0 to 3, and M is as defined above. It is represented by). As the compound (XIII), CF2ClO(CF2CF(CF3)O) n9 (CF2O) n10 CF2COONH4 (a mixture with an average molecular weight of 750, where n9 and n10 are as defined above).

[0227] As described above, examples of the anionic fluorine-containing surfactant include carboxylic acid surfactants and sulfonic acid surfactants.

[0228] It is also preferable that the first treatment method of the present disclosure includes a pretreatment step of removing solid components from the water containing the polymer (I) before the above removal step when the water containing the polymer (I) contains solid components. Examples of the solid components include uncondensed polymers, flocculants, and particulate polymers. The above solid components can be, for example, components remaining in water after separating and recovering the polymer produced in the above polymer production process. For example, in the solid-liquid separation step as the above polymer production process, the liquid containing the polymer (I) remaining after separating and recovering the polymer, that is, the water after separating and recovering the polymer, may contain uncondensed polymers that could not be completely recovered in the solid-liquid separation step. When removing the polymer (I) from the liquid containing the polymer (I) remaining after separating and recovering the polymer, such solid components can have an adverse effect on the process of removing the polymer (I), so it is desirable to remove them from the water before the removal step. In this specification, the uncondensed polymer is a polymer component that is dispersed in the water remaining after adding a flocculant and performing a solid-liquid separation step to separate and recover the polymer after the polymerization step of the polymer, and means a substance that accumulates as a gel-like substance on the surface of a filter medium such as a filter. The particle size of the uncondensed polymer may be about 0.01 μm to 5.0 μm. The particulate polymer that may be contained in water containing the polymer (I) is not limited in its particle size. For example, it may be a polymer with a particle size of about 0.1 μm to 0.2 μm. That is, the water containing the polymer (I) may contain a solid component, and may contain an uncondensed polymer and / or a particulate polymer as the solid component. In the first treatment method of the present disclosure, the concentration of the solid component in the water containing the polymer (I) is not particularly limited, and water with any solid component concentration can be treated. The concentration of the solid component in the water containing the polymer (I) can vary depending on the polymer production process. For example, it may be 0.1 ppm to 50000 ppm. Also, by the above pretreatment step, for example, it is preferable to adjust the solid component in the water containing the polymer (I) to 0.05 ppm to 500 ppm, more preferably to 0.05 ppm to 50 ppm, and even more preferably to 0.05 ppm to 10 ppm. The lower limit of the solid component may be 0.1 ppm. The method for removing the solid component is not limited, and examples include filtration. Examples of the filtration method include a method of separating the solid component with a UF membrane or an MF membrane, a method using a filter aid, and a method using a liquid cyclone. Examples of the above MF membrane include a sanitary filter, a hollow fiber membrane, a flat membrane, a spiral, etc. Examples of the above filter aid include diatomaceous earth, filter sand (manganese sand, manganese zeolite, anthracite, ceramic sand, etc.), perlite, cellulose, etc.

[0229] The polymer (I) may also be a water-soluble polymer in which the proportion of hydrogen atoms bonded to carbon atoms replaced by fluorine atoms is 50% or more, or a polymer (polymer α) in which the proportion of hydrogen atoms bonded to carbon atoms replaced by fluorine atoms is 50% or more, and which contains an ionic group and has an ion exchange rate of 53 or less.

[0230] The present disclosure also provides a composition (hereinafter also referred to as "the first composition of the present disclosure") comprising a polymer (I) containing a polymerizable unit (I) based on a monomer represented by the following general formula (I), water, and a fluorine-containing polymer (excluding the polymer (I)), wherein the content of the polymer (I) is 250 ppm or less. CX 1 X 3 =CX 2 R(-CZ 1 Z 2 -A 0 ) m (I) (In the formula, X 1 and X 3 are each independently F, Cl, H, or CF3; X 2 is H, F, an alkyl group, or a fluorinated alkyl group; A 0 is an anionic group; R is a linking group; Z 1 and Z 2 are each independently H, F, an alkyl group, or a fluorinated alkyl group; and m is an integer of 1 or more.) The first composition of the present disclosure may be an aqueous solution of the polymer (I) or a dispersion of the polymer (I).

[0231] In the first composition of the present disclosure, the polymer (I) is the same as that described in the first treatment method of the present disclosure, and appropriate preferred embodiments can be adopted as appropriate. Among them, the above-described polymer (1) is preferred.

[0232] In the first composition of the present disclosure, the content of the polymer (I) is 250 ppm or less based on the mass of the composition. The content of the polymer (I) is preferably 200 ppm or less, more preferably 150 ppm or less, still more preferably 100 ppm or less, still more preferably 50 ppm or less, particularly preferably 25 ppm or less, and most preferably 10 ppm or less. The lower limit of the above content is not particularly limited, but is preferably 0.1 ppm or more, more preferably 0.5 ppm or more, still more preferably 1 ppm or more, still more preferably 2 ppm or more, and particularly preferably 5 ppm or more. The content of the polymer (I) contained in the first composition of the present disclosure can be measured in the same manner as the water containing the polymer (I). For example, it can be determined by solid NMR measurement. The first composition of the present disclosure may contain one single polymer (I) or may contain two or more different polymers (I).

[0233] The first composition of the present disclosure contains a fluorine-containing polymer other than the polymer (I). As the fluorine-containing polymer other than the polymer (I), the fluorine-containing polymer other than the polymer (I) described in the first treatment method of the present disclosure can be appropriately adopted, and an appropriate preferred embodiment can be adopted. As the fluorine-containing polymer other than the polymer (I), a fluorine-containing polymer having an ion exchange rate (IXR) higher than 53 is preferable. Further, as the fluorine-containing polymer other than the polymer (I), PTFE is preferable. When the first composition of the present disclosure contains PTFE, the PTFE may be a TFE homopolymer, or may be a modified PTFE containing a modified monomer unit based on a modified monomer copolymerizable with the TFE unit and the TFE, and may also be a high molecular weight PTFE or a low molecular weight PTFE. As the PTFE in the composition of the present disclosure, the PTFE described in the first treatment method of the present disclosure can be appropriately adopted.

[0234] In the first composition of the present disclosure, the content of the fluorine-containing polymer other than the polymer (I) is preferably 5000 ppm or less, more preferably 2000 ppm or less, still more preferably 1000 ppm or less, and particularly preferably 500 ppm or less, based on the mass of the composition. The lower limit value of the above content is not particularly limited, but may be substantially 0 ppm, may be more than 0 ppm, may be 1 ppm or more, or may be 100 ppm or more. The content of the fluorine-containing polymer other than the polymer (I) can be determined by a method of separating the solid component (fluorine-containing polymer other than the polymer (I)) with an MF membrane. When the first composition of the present disclosure contains PTFE, the content of PTFE is preferably 5000 ppm or less, more preferably 2000 ppm or less, still more preferably 1000 ppm or less, and particularly preferably 500 ppm or less, based on the mass of the composition. The lower limit of the above content is not particularly limited, and may be substantially 0 ppm, may be more than 0 ppm, may be 1 ppm or more, or may be 100 ppm or more. The content of the above PTFE can be determined by a method of separating the solid component (PTFE) with an MF membrane.

[0235] The first composition of the present disclosure may contain a polymer (I), water, and substances other than fluorine-containing polymers. The first composition of the present disclosure may contain, for example, a flocculant or the like described in the first treatment method of the present disclosure. Further, the first composition of the present disclosure may contain metal ions, or may contain metal ions of divalent or higher. As the metal ions of divalent or higher, those contained in the third composition of the present disclosure described later can be appropriately contained. The content of the metal ions of divalent or higher is preferably 0.05 mg / L or more, more preferably 0.1 mg / L or more, still more preferably 0.15 mg / L or more, and particularly preferably 0.2 mg / L or more, based on the composition. Also, the content of the metal ions of divalent or higher is preferably 1000 mg / L or less, more preferably 500 mg / L or less, still more preferably 250 mg / L or less, still more preferably 100 mg / L or less, particularly preferably 50 mg / L or less, most preferably 10 mg / L or less.

[0236] In the first composition of the present disclosure, the total amount of the polymer (I), water, and fluorine-containing polymers other than the polymer (I) is preferably 95.0% by mass or more, more preferably 99.0% by mass or more, still more preferably 99.9% by mass or more, and particularly preferably consisting essentially of only the polymer (I), water, and fluorine-containing polymers other than the polymer (I).

[0237] The first composition of the present disclosure can be obtained by removing the polymer (I) from the water generated in the above-described fluoropolymer production process. As the above removal method, the embodiments described in the first treatment method of the present disclosure described above can be appropriately adopted. In particular, as the removal step, a step of aggregating the polymer (I) and adding an inorganic flocculant to the water containing the polymer (I) is adopted, and the first composition of the present disclosure can be preferably obtained by this method.

[0238] The present disclosure also provides a composition (hereinafter also referred to as "the second composition of the present disclosure") containing a polymer (I) containing a polymerized unit (I) based on a monomer represented by the following general formula (I), water, and divalent or higher metal ions, wherein the content of the polymer (I) is 250 ppm or less. CX 1 X 3 =CX 2 R(-CZ 1 Z 2 -A 0 ) m (I) (In the formula, X 1 and X 3 are each independently F, Cl, H, or CF3; X 2 is H, F, an alkyl group, or a fluorinated alkyl group; A 0 is an anionic group; R is a linking group; Z 1 and Z 2 are each independently H, F, an alkyl group, or a fluorinated alkyl group; and m is an integer of 1 or more.) The second composition of the present disclosure may be an aqueous solution of the polymer (I) or a dispersion of the polymer (I).

[0239] In the second composition of the present disclosure, the polymer (I) is the same as that described in the first treatment method of the present disclosure, and appropriate preferred embodiments can be adopted. Among them, the above-described polymer (1) is preferred.

[0240] The content of polymer (I) in the second composition of the present disclosure is 250 ppm or less based on the mass of the composition. The content of polymer (I) is preferably 200 ppm or less, more preferably 150 ppm or less, still more preferably 100 ppm or less, even more preferably 50 ppm or less, particularly preferably 25 ppm or less, and most preferably 10 ppm or less. The lower limit of the above content is not particularly limited, but is preferably 0.1 ppm or more, more preferably 0.5 ppm or more, still more preferably 1 ppm or more, even more preferably 2 ppm or more, and particularly preferably 5 ppm or more. The content of polymer (I) contained in the second composition of the present disclosure can be measured in the same manner as the water containing polymer (I). For example, it is determined by solid NMR measurement. The second composition of the present disclosure may contain one single polymer (I) or two or more different polymers (I).

[0241] The second composition of the present disclosure contains divalent or higher metal ions. The divalent or higher metal ions are not particularly limited, but are preferably, for example, the ions of the metals constituting the metal salts described as the above-mentioned inorganic flocculants, and at least one selected from the group consisting of Fe, Al, and Ca is preferable. In the second composition of the present disclosure, the content of the divalent or higher metal ions is preferably 0.05 mg / L or more based on the composition. More preferably, it is 0.1 mg / L or more, still more preferably 0.15 mg / L or more, and particularly preferably 0.2 mg / L or more. Also, the content of the divalent or higher metal ions is preferably 1000 mg / L or less, more preferably 500 mg / L or less, still more preferably 250 mg / L or less, even more preferably 100 mg / L or less, particularly preferably 50 mg / L or less, most preferably 10 mg / L or less, and most preferably 5 mg / L or less. The content of the divalent or higher metal ions is measured by the method of the pack test (manufactured by Kyoritsu Chemical-Check Laboratory Co., Ltd.).

[0242] The second composition of the present disclosure may contain a polymer (I), water, and substances other than divalent or higher metal ions. For example, it may contain a flocculant or the like described in the first treatment method of the present disclosure. Further, the second composition of the present disclosure may contain a fluorine-containing polymer other than the polymer (I). As the fluorine-containing polymer other than the polymer (I), those contained in the first composition of the present disclosure can be appropriately employed. As the fluorine-containing polymer other than the polymer (I), a fluorine-containing polymer having an ion exchange rate (IXR) higher than 53 is preferable. Further, the second composition of the present disclosure may contain PTFE. The PTFE is the same as that which can be contained in the first composition of the present disclosure. In the second composition of the present disclosure, the content of the fluorine-containing polymer other than the polymer (I) is preferably 5000 ppm or less based on the mass of the composition. More preferably, it is 2000 ppm or less, still more preferably 1000 ppm or less, and particularly preferably 500 ppm or less. The lower limit value of the above content is not particularly limited, but it may be substantially 0 ppm, may be more than 0 ppm, may be 1 ppm or more, or may be 100 ppm or more. The content of the fluorine-containing polymer other than the polymer (I) can be determined by a method of separating the solid component (fluorine-containing polymer other than the polymer (I)) with an MF membrane. When the second composition of the present disclosure contains PTFE, the content of PTFE is preferably 5000 ppm or less based on the mass of the composition. More preferably, it is 2000 ppm or less, still more preferably 1000 ppm or less, and particularly preferably 500 ppm or less. The lower limit value of the above content is not particularly limited, but it may be substantially 0 ppm, may be more than 0 ppm, may be 1 ppm or more, or may be 100 ppm or more. The content of the above PTFE can be determined by a method of separating the solid component (PTFE) with an MF membrane.

[0243] In the second composition of the present disclosure, it is preferable that the total amount of the polymer (I), water, and divalent or higher metal ions is 95.0% by mass or more, preferably 99.0% by mass or more, more preferably 99.9% by mass or more, and it is particularly preferable that it consists essentially of only the polymer (I), water, and divalent or higher metal ions.

[0244] The second composition of the present disclosure can be obtained by removing the polymer (I) from the water generated in the above-described fluorine-containing polymer production process. As the method for the above removal, the modes described in the first treatment method of the present disclosure described above can be appropriately adopted. In particular, as the removal step, a method that aggregates the polymer (I) and employs a step of adding an inorganic flocculant (preferably a metal salt) to the water containing the polymer (I) can preferably obtain the second composition of the present disclosure.

[0245] The present disclosure also provides a water treatment method (hereinafter also referred to as "the second treatment method of the present disclosure") characterized by including a step of removing a water-soluble polymer contained in water containing a water-soluble polymer in which the ratio of hydrogen atoms bonded to carbon atoms substituted by fluorine atoms is 50% or more. Water-soluble means the property of being easily dissolved or dispersed in water. For a water-soluble polymer, for example, the particle size cannot be measured by the dynamic light scattering method (DLS). On the other hand, for a polymer having water-insolubility, for example, the particle size can be measured by the dynamic light scattering method (DLS). In the second treatment method of the present disclosure, the above removal step can adopt all the same methods as the first treatment method of the present disclosure, except for using water containing a water-soluble polymer in which the ratio of hydrogen atoms bonded to carbon atoms substituted by fluorine atoms is 50% or more. Note that the "ratio of hydrogen atoms bonded to carbon atoms substituted by fluorine atoms" is determined as the ratio of the number of fluorine atoms to the total number of hydrogen atoms bonded to carbon atoms and halogen atoms (including fluorine atoms) bonded to carbon atoms. The above removal step is preferably a step of performing aggregation in water containing a water-soluble polymer, more preferably a step of adding a flocculant to water containing a water-soluble polymer, still more preferably a step of adding an inorganic flocculant to water containing a water-soluble polymer, and particularly preferably a step of adding an inorganic flocculant to water containing a water-soluble polymer and then adding a polymer flocculant. As the flocculant, inorganic flocculant, and polymer flocculant, those described in the first treatment method of the present disclosure can be appropriately employed.

[0246] In the second treatment method of the present disclosure, it is preferable that the above removal step is a step of reducing the concentration of the water-soluble polymer in the water containing the water-soluble polymer to 50% or less with respect to the concentration before the removal step. More preferably, it is 40% or less, still more preferably 30% or less, particularly preferably 20% or less, and most preferably 10% or less. The above removal step is also preferably a step of reducing the concentration of the water-soluble polymer in the treated water to 250 ppm or less. More preferably, it is 200 ppm or less, still more preferably 100 ppm or less, still more preferably 80 ppm or less, particularly preferably 60 ppm or less, and most preferably 50 ppm or less.

[0247] The water-soluble polymer is not particularly limited, and a water-soluble polymer in which the ratio of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms is 50% or more among the above-described polymer (I) can be used, or a water-soluble polymer in which the ratio of hydrogen atoms bonded to carbon atoms other than the above-described polymer (I) substituted with fluorine atoms is 50% or more can also be used.

[0248] Examples of the water-soluble polymer include the following general formula (I): CX 1 X 3 =CX 2 R(-CZ 1 Z 2 -A 0 ) m (I) (In the formula, X 1 and X 3is independently F, Cl, H or CF3; X 2 is H, F, an alkyl group or a fluorine-containing alkyl group; A 0 is an anionic group; R is a linking group; Z 1 and Z 2 are independently H, F, an alkyl group or a fluorine-containing alkyl group; m is an integer of 1 or more.) Examples include water-soluble polymers containing a polymer unit (I) based on a monomer represented by . In the above water-soluble polymer, the content of the polymer unit (I) is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, especially preferably 95% by mass or more, and most preferably 99% by mass or more.

[0249] The above water-soluble polymer may contain a polymer unit based on a fluorine-containing monomer based on trifluoroethylene, tetrafluoroethylene (TFE), vinylidene fluoride (VdF), vinyl fluoride (VF), chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), hexafluoroisobutylene, perfluoroalkyl ethylene, fluorovinyl ether (FVE), CH2 = CFCF3, CHF = CHCF3 (E isomer), CHF = CHCF3 (Z isomer), etc.

[0250] The above water-soluble polymer may also contain a polymer unit based on a non-fluorine-containing monomer. The non-fluorine-containing monomer may be any monomer having a radically polymerizable ethylenically unsaturated bond. For example, acrylic acid esters, methacrylic acid esters, unsaturated carboxylic acids, hydrolyzable silyl group-containing monomers, hydroxyl group-containing alkyl vinyl ethers, carboxylic acid vinyl esters, α-olefins, etc. may be mentioned. Among the above non-fluorine-containing monomers, at least one selected from the group consisting of acrylic acid esters, methacrylic acid esters, unsaturated carboxylic acids, and hydrolyzable silyl group-containing monomers is preferable. In addition, as the non-fluorine-containing monomer, at least one monomer selected from the group consisting of acrylic esters and methacrylic esters, unsaturated carboxylic acids, and at least one selected from the group consisting of monomers containing a hydrolyzable silyl group is more preferable. In addition, a monomer having a radically polymerizable ethylenic unsaturated bond may be used in combination.

[0251] As the acrylic ester or methacrylic ester, an acrylic acid alkyl ester having an alkyl group with 1 to 10 carbon atoms or a methacrylic acid alkyl ester having an alkyl group with 1 to 10 carbon atoms is preferable. Examples of the acrylic acid alkyl ester and methacrylic acid alkyl ester include (meth)acrylic acid alkyl esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, methyl methacrylate, n-propyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, cyclohexyl acrylate, and cyclohexyl methacrylate. Further, the acrylic acid alkyl ester or methacrylic acid alkyl ester may be a hydroxyl group-containing acrylic monomer having a hydroxyl group and a (meth)acryloyl group in the molecule, such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and 4-hydroxybutyl methacrylate. These acrylic esters or methacrylic esters may be used alone or in combination of two or more, and n-butyl acrylate and methyl methacrylate are preferable.

[0252] As the non-fluorine-containing monomer, at least one (meth)acrylic acid alkyl ester selected from the group consisting of methyl methacrylate, n-butyl acrylate, 2-ethylhexyl methacrylate, and cyclohexyl methacrylate is preferable. Note that the acrylic acid ester or methacrylic acid ester does not contain a hydrolyzable silyl group.

[0253] As the acrylic acid ester or methacrylic acid ester, a combination of n-butyl acrylate and methyl methacrylate or a combination of n-butyl acrylate, methyl methacrylate, and 2-ethylhexyl methacrylate is more preferable, and a combination of n-butyl acrylate, methyl methacrylate, and 2-ethylhexyl methacrylate is particularly preferable. In addition, it is also preferable to combine a hydroxyl group-containing acrylic monomer having a hydroxyl group and a (meth)acryloyl group.

[0254] Specific examples of the unsaturated carboxylic acids include, for example, acrylic acid, methacrylic acid, vinyl acetic acid, crotonic acid, cinnamic acid, 3-allyloxypropionic acid, 3-(2-allyloxyethoxycarbonyl)propionic acid, itaconic acid, itaconic acid monoester, maleic acid, maleic acid monoester, maleic anhydride, fumaric acid, fumaric acid monoester, vinyl phthalate, vinyl pyromellitate, undecylenic acid, and the like. Among them, at least one selected from the group consisting of acrylic acid, methacrylic acid, vinyl acetic acid, crotonic acid, itaconic acid, maleic acid, maleic acid monoester, fumaric acid, fumaric acid monoester, 3-allyloxypropionic acid, and undecylenic acid is preferable in terms of low homopolymerizability and difficulty in forming a homopolymer and easy control of the introduction of a carboxyl group.

[0255] As the hydrolyzable silyl group-containing monomer, CH2=CHCOO(CH2)3Si(OCH3)3, CH2=CHCOO(CH2)3Si(CH3)(OCH3)2, CH2=CHCOO(CH2)3Si(OC2H5)3, CH2=CHCOO(CH2)3Si(CH3)(OC2H5)2, CH2=C(CH3)COO(CH2)3Si(OCH3)3, CH2=C(CH3)COO(CH2)3Si(CH3)(OCH3)2, CH2=C(CH3)COO(CH2)3Si(OC2H5)3, CH2=C(CH3)COO(CH2)3Si(CH3)(OC2H5)2, CH2=C(CH3)COO(CH2)2O(CH2)3Si(OCH3)3, CH2=C(CH3)COO(CH2)2(CH2)3Si(CH3)(OCH3)2, CH2=C(CH3)COO(CH2) 11 Si(OCH3)3, CH2=C(CH3)COO(CH2) 11 Si(CH3)(OCH3)2, and the like. These hydrolyzable silyl group-containing monomers may be used alone or in combination of two or more.

[0256] Among the above hydrolyzable silyl group-containing monomers, at least one selected from the group consisting of γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltriethoxysilane, and γ-methacryloxypropylmethyldiethoxysilane is preferable, and γ-methacryloxypropyltriethoxysilane is more preferable.

[0257] Examples of the above-mentioned hydroxyl group-containing alkyl vinyl ethers include 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 2-hydroxy-2-methylpropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxy-2-methylbutyl vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, 2-hydroxyethyl allyl ether, 4-hydroxybutyl allyl ether, glycerol monoallyl ether, and the like. In terms of excellent polymerization reactivity, at least one selected from the group consisting of 4-hydroxybutyl vinyl ether and 2-hydroxyethyl vinyl ether is preferable.

[0258] Examples of the vinyl carboxylates include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caproate, vinyl versatate, vinyl laurate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl benzoate, vinyl p-t-butylbenzoate, and the like.

[0259] Examples of the α-olefins include ethylene, propylene, n-butene, isobutene, styrene, and the like.

[0260] The number average molecular weight of the above-mentioned water-soluble polymer is preferably 0.1×10 4 or more, more preferably 0.2×10 4 or more, still more preferably 0.3×10 4 or more, particularly preferably 0.4×10 4 or more, especially preferably 0.5×10 4 or more, particularly preferably 1.0×10 4 or more, especially preferably 3.0×10 4 or more, most preferably 3.1×10 4 or more. Also, it is preferably 75.0×10 4 or less, more preferably 50.0×10 4 or less, still more preferably 40.0×10 4 or less, and even more preferably 30.0×10 4The following is more preferable, 20.0×10 4 The following is particularly preferable. The weight-average molecular weight of the above water-soluble polymer is 0.2×10 4 The above is preferable, 0.4×10 4 The above is more preferable, 0.6×10 4 The above is even more preferable, 0.8×10 4 The above is even more preferable, 1.0×10 4 The above is particularly preferable, 5.0×10 4 The above is more particularly preferable, 10.0×10 4 The above is even more particularly preferable, 15.0×10 4 The above is even more preferably, 20.0×10 4 The above is even more particularly preferably, 25.0×10 4 The above is most preferable. Also, 150.0×10 4 The following is preferable, 100.0×10 4 The following is more preferable, 60.0×10 4 The following is even more preferable, 50.0×10 4 The following is particularly preferable, 40.0×10 4 The following is even more preferably. The above number-average molecular weight and weight-average molecular weight are values calculated by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard. Also, when measurement by GPC cannot be performed, the number-average molecular weight of the water-soluble polymer can be determined by the correlation between the number-average molecular weight calculated from the number of terminal groups obtained by NMR, FT-IR, etc. and the melt flow rate. The melt flow rate can be measured in accordance with JIS K 7210.

[0261] The above water-soluble polymer preferably has an ion exchange rate (IXR) of 53 or less. The above IXR is preferably 0.5 or more, more preferably 1 or more, even more preferably 3 or more, even more preferably 4 or more, even more preferably 5 or more, particularly preferably 8 or more. Also, the IXR is more preferably 43 or less, even more preferably 33 or less, particularly preferably 23 or less. In the above water-soluble polymer, the ionic group (anionic group) is typically distributed along the polymer main chain. The above water-soluble polymer includes the polymer main chain together with repeating side chains bonded to this main chain, and it is preferable that this side chain has an ionic group. The water-soluble polymer preferably contains an ionic group (anionic group) having a pKa of less than 10, more preferably less than 7. The ionic group of the water-soluble polymer is preferably selected from the group consisting of sulfonates, carboxylates, phosphonates, phosphates, and mixtures thereof. The terms "sulfonate, carboxylate, phosphonate, and phosphate" are intended to refer to the respective salts or the respective acids capable of forming salts. When a salt is used, preferably, the salt is an alkali metal salt or an ammonium salt. A preferred ionic group is a sulfonate group.

[0262] The water containing the above water-soluble polymer is not particularly limited, and examples include water generated in polymer production processes such as the production process of the above water-soluble polymer and the polymer polymerization process using the above water-soluble polymer. The water containing the above water-soluble polymer may be wastewater.

[0263] In the water containing the above water-soluble polymer, the content of the water-soluble polymer is not particularly limited, but for example, from the viewpoint of enhancing the removal efficiency, it is preferably 10% by mass or less. In the water containing the above water-soluble polymer, the content of the water-soluble polymer is more preferably 1% by mass or less, still more preferably 0.5% by mass or less, and particularly preferably 0.2% by mass or less. Also, it may be more than 0% by mass, may be more than 0.005% by mass, may be more than 0.006% by mass, may be more than 0.008% by mass, may be 0.010% by mass or more, may be more than 0.020% by mass, may be more than 0.025% by mass, or may be 0.1% by mass or more. The content of the above water-soluble polymer can be measured, for example, by solid NMR. The water containing the above water-soluble polymer may contain one single water-soluble polymer or two or more different water-soluble polymers.

[0264] The water containing the above water-soluble polymer may contain substances other than the water-soluble polymer and water, and may be a dispersion liquid, an aqueous solution, or the like. Examples of substances other than the water-soluble polymer and water include non-fluorine polymers other than the water-soluble polymer, fluorine-containing polymers other than the water-soluble polymer, oligomers, and the like. The fluorine-containing polymer other than the water-soluble polymer is a fluorine-containing polymer in which the ratio of hydrogen atoms bonded to carbon atoms replaced by fluorine atoms is less than 50%, or a water-insoluble fluorine-containing polymer. Examples of the fluorine-containing polymer other than the water-soluble polymer include fluorine-containing polymers having an ion exchange rate (IXR) higher than 53. Preferred fluorine-containing polymers other than the water-soluble polymer have no ionic groups or have a limited number of ionic groups that result in an ion exchange rate higher than about 100. The ion exchange rate of the fluorine-containing polymer other than the water-soluble polymer is preferably more than 53, more preferably 100 or more, still more preferably 1000 or more, particularly preferably 2000 or more, and especially preferably 5000 or more. Examples of the fluorine-containing polymer other than the above water-soluble polymer include those described in the first treatment method of the present disclosure. For example, copolymers of PTFE, TFE, and another monomer copolymerizable with TFE (fluorine-containing monomers such as vinylidene fluoride, hexafluoropropylene, chlorotrifluoroethylene, perfluoro(alkyl vinyl ether), etc., hydrocarbon olefins such as ethylene, propylene, isobutene, etc., alkyl vinyl ether, etc.) (for example, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA), and ethylene-tetrafluoroethylene copolymer (ETFE), etc.), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), and fluororesins such as ethylene-chlorotrifluoroethylene (ECTFE), vinylidene fluoride-based rubbers such as vinylidene fluoride-hexafluoropropylene copolymer (FKM), fluorine rubbers such as tetrafluoroethylene-propylene rubber (FEPM), and tetrafluoroethylene-perfluoromethyl vinyl ether rubber (FFKM), and fluorine-containing elastomers, etc. The above PTFE may be a homopolymer of TFE or a modified PTFE containing 99.0% by mass or more of TFE and 1.0% by weight or less of a modified monomer. As the fluorine-containing polymer other than the above water-soluble polymer, at least one selected from the group consisting of PTFE and a melt-processable fluororesin containing 60.0 to 98.0% by mass of TFE units and 2.0 to 40.0% by mass of other monomers is preferable, and PTFE is more preferable.

[0265] The water containing the above water-soluble polymer preferably has a content of substances other than the water-soluble polymer and water of 1.0% by mass or less, more preferably 0.5% by mass or less, and still more preferably 0.2% by mass or less. The lower limit of the content of substances other than the water-soluble polymer and water is not limited, and may be, for example, 0% by mass or 0.1% by mass. The water containing the above-mentioned water-soluble polymer preferably has a water content of 99.0% by mass or more. More preferably, it is 99.5% by mass or more, and still more preferably, it is 99.8% by mass or more.

[0266] The present disclosure also provides a composition (hereinafter also referred to as "the third composition of the present disclosure") containing a water-soluble polymer in which 50% or more of the hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms, water, and a fluorine-containing polymer (excluding the above-mentioned water-soluble polymer), characterized in that the content of the water-soluble polymer is 250 ppm or less. The third composition of the present disclosure is preferably an aqueous solution of a water-soluble polymer.

[0267] In the third composition of the present disclosure, the water-soluble polymer is the same as that described in the second treatment method of the present disclosure, and appropriate preferred embodiments can be adopted as appropriate.

[0268] In the third composition of the present disclosure, the content of the water-soluble polymer is 250 ppm or less based on the mass of the composition. The content of the water-soluble polymer is preferably 200 ppm or less, more preferably 150 ppm or less, still more preferably 100 ppm or less, still more preferably 50 ppm or less, particularly preferably 25 ppm or less, and most preferably 10 ppm or less. The lower limit of the above content is not particularly limited, but is preferably 0.1 ppm or more, more preferably 0.5 ppm or more, still more preferably 1 ppm or more, still more preferably 2 ppm or more, and particularly preferably 5 ppm or more. The content of the water-soluble polymer contained in the third composition of the present disclosure can be measured in the same manner as the water containing the water-soluble polymer. For example, it is determined by solid NMR measurement. The third composition of the present disclosure may contain one single water-soluble polymer or two or more different water-soluble polymers.

[0269] The third composition of the present disclosure contains a fluorine-containing polymer other than a water-soluble polymer. As the fluorine-containing polymer other than the water-soluble polymer, the fluorine-containing polymer other than the water-soluble polymer described in the second treatment method of the present disclosure can be appropriately adopted, and an appropriately preferred embodiment can be adopted. The ion exchange rate of the fluorine-containing polymer other than the water-soluble polymer is preferably more than 53, more preferably 100 or more, still more preferably 1000 or more, particularly preferably 2000 or more, and especially preferably 5000 or more. As the fluorine-containing polymer other than the water-soluble polymer, PTFE is preferred.

[0270] In the third composition of the present disclosure, the content of the fluorine-containing polymer other than the water-soluble polymer is preferably 5000 ppm or less, more preferably 2000 ppm or less, still more preferably 1000 ppm or less, and particularly preferably 500 ppm or less, based on the mass of the composition. The lower limit value of the above content is not particularly limited, but may be substantially 0 ppm, may be more than 0 ppm, may be 1 ppm or more, or may be 100 ppm or more. The content of the fluorine-containing polymer other than the water-soluble polymer can be determined by a method of separating the solid component (fluorine-containing polymer other than the water-soluble polymer) with an MF membrane.

[0271] The third composition of the present disclosure may contain substances other than the water-soluble polymer, water, and the fluorine-containing polymer other than the water-soluble polymer. For example, it may contain a flocculant or the like described in the second treatment method of the present disclosure. Further, the third composition of the present disclosure may contain metal ions, or may contain divalent or higher metal ions. As the divalent or higher metal ions, those contained in the second composition of the present disclosure can be appropriately contained. The content of divalent or higher metal ions is preferably 0.05 mg / L or more, more preferably 0.1 mg / L or more, still more preferably 0.15 mg / L or more, and particularly preferably 0.2 mg / L or more, based on the composition. Also, the content of divalent or higher metal ions is preferably 1000 mg / L or less, more preferably 500 mg / L or less, still more preferably 250 mg / L or less, even more preferably 100 mg / L or less, particularly preferably 50 mg / L or less, and most preferably 5 mg / L or less.

[0272] In the third composition of the present disclosure, the total amount of the water-soluble polymer, water, and the fluorine-containing polymer other than the water-soluble polymer is preferably 95.0% by mass or more, more preferably 99.0% by mass or more, still more preferably 99.9% by mass or more, and particularly preferably consisting essentially of only the water-soluble polymer, water, and the fluorine-containing polymer other than the water-soluble polymer.

[0273] The third composition of the present disclosure can be obtained by removing the water-soluble polymer from the water containing the water-soluble polymer described in the second treatment method of the present disclosure. As the above-mentioned removal method, the modes described in the second treatment method of the present disclosure can be appropriately adopted. In particular, as the removal step, a method that causes aggregation in the water-soluble polymer and adopts a step of adding an inorganic flocculant to the water containing the water-soluble polymer can preferably obtain the third composition of the present disclosure.

[0274] The present disclosure also provides a composition (hereinafter also referred to as "the fourth composition of the present disclosure") containing a water-soluble polymer in which 50% or more of the hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms, water, and divalent or higher metal ions, and the content of the water-soluble polymer is 250 ppm or less. The fourth composition of the present disclosure is preferably an aqueous solution of the water-soluble polymer.

[0275] In the fourth composition of the present disclosure, the water-soluble polymer is the same as the water-soluble polymer described in the second treatment method of the present disclosure, and appropriate preferred modes can be adopted.

[0276] The content of the water-soluble polymer in the fourth composition of the present disclosure is 250 ppm or less based on the mass of the composition. The content of the water-soluble polymer is preferably 200 ppm or less, more preferably 150 ppm or less, still more preferably 100 ppm or less, still more preferably 50 ppm or less, particularly preferably 25 ppm or less, and particularly preferably 10 ppm or less. The lower limit of the above content is not particularly limited, but is preferably 0.1 ppm or more, more preferably 0.5 ppm or more, still more preferably 1 ppm or more, still more preferably 2 ppm or more, and particularly preferably 5 ppm or more. The content of the water-soluble polymer contained in the fourth composition of the present disclosure can be measured in the same manner as the water containing the water-soluble polymer. For example, it is determined by solid NMR measurement. The fourth composition of the present disclosure may contain one single water-soluble polymer or two or more different water-soluble polymers.

[0277] The fourth composition of the present disclosure contains divalent or higher metal ions. The divalent or higher metal ions are not particularly limited, but are preferably, for example, the ions of the metals constituting the metal salts described as the above-mentioned inorganic flocculants. For example, at least one selected from the group consisting of Fe, Al, and Ca is preferable. The fourth composition of the present disclosure preferably has a content of the divalent or higher metal ions of 0.05 mg / L or more based on the composition. More preferably, it is 0.1 mg / L or more, still more preferably 0.15 mg / L or more, and particularly preferably 0.2 mg / L or more. Also, the content of the divalent or higher metal ions is preferably 1000 mg / L or less, more preferably 500 mg / L or less, still more preferably 250 mg / L or less, still more preferably 100 mg / L or less, particularly preferably 50 mg / L or less, particularly preferably 10 mg / L or less, and most preferably 5 mg / L or less. The content of the divalent or higher metal ions is measured by the method of the pack test (manufactured by Kyoritsu Chemical-Check Laboratory Co., Ltd.).

[0278] The fourth composition of the present disclosure may contain a water-soluble polymer, water, and substances other than divalent or higher metal ions. For example, it may contain a flocculant or the like described in the first treatment method of the present disclosure. Further, the fourth composition of the present disclosure may contain a fluorine-containing polymer other than the water-soluble polymer. As the fluorine-containing polymer other than the water-soluble polymer, those described in the second treatment method of the present disclosure can be appropriately adopted. As the fluorine-containing polymer other than the water-soluble polymer, a fluorine-containing polymer having an ion exchange rate (IXR) higher than 53 is preferable. Further, the fourth composition of the present disclosure may contain PTFE. As the above PTFE, those described in the second treatment method of the present disclosure can be appropriately adopted. In the fourth composition of the present disclosure, the content of the fluorine-containing polymer other than the water-soluble polymer is preferably 5000 ppm or less, more preferably 2000 ppm or less, still more preferably 1000 ppm or less, and particularly preferably 500 ppm or less, based on the mass of the composition. The lower limit value of the above content is not particularly limited, but may be substantially 0 ppm, may be more than 0 ppm, may be 1 ppm or more, or may be 100 ppm or more. The content of the fluorine-containing polymer other than the water-soluble polymer can be determined by a method of separating the solid component (fluorine-containing polymer other than the water-soluble polymer) with an MF membrane.

[0279] In the fourth composition of the present disclosure, the total amount of the water-soluble polymer, water, and divalent or higher metal ions is preferably 95.0% by mass or more, preferably 99.0% by mass or more, more preferably 99.9% by mass or more, and particularly preferably consisting essentially of only the water-soluble polymer, water, and divalent or higher metal ions.

[0280] The fourth composition of the present disclosure can be obtained by removing the water-soluble polymer from the water containing the water-soluble polymer described in the second treatment method of the present disclosure. As the method for the above removal, the modes described in the second treatment method of the present disclosure described above can be appropriately adopted. In particular, as the removal step, a method that causes aggregation of the water-soluble polymer and adopts a step of adding an inorganic flocculant (preferably a metal salt) to the water containing the water-soluble polymer can preferably obtain the fourth composition of the present disclosure.

[0281] The present disclosure also provides a water treatment method (hereinafter also referred to as "the third treatment method of the present disclosure") including a step of removing a polymer from water containing a polymer in which the proportion of hydrogen atoms bonded to carbon atoms substituted by fluorine atoms is 50% or more, which contains an ionic group, and has an ion exchange rate of 53 or less. In the third treatment method of the present disclosure, the above removal step can adopt all the same methods as the first treatment method of the present disclosure, except for using water containing a polymer in which the proportion of hydrogen atoms bonded to carbon atoms substituted by fluorine atoms is 50% or more, which contains an ionic group, and has an ion exchange rate of 53 or less (hereinafter also referred to as "polymer α"). The above removal step preferably causes aggregation of the water containing polymer α, more preferably is a step of adding a flocculant to the water containing polymer α, still more preferably is a step of adding an inorganic flocculant to the water containing polymer α, and particularly preferably is a step of adding an inorganic flocculant to the water containing polymer α and then adding a polymeric flocculant. As the flocculant, inorganic flocculant, and polymeric flocculant, those described in the first treatment method of the present disclosure can be appropriately adopted. The water containing the above polymer α is not particularly limited, and examples include water generated in polymer production processes such as the production process of the above polymer α and the polymer polymerization process using the above polymer α. The water containing the above polymer α may be wastewater.

[0282] In the third treatment method of the present disclosure, the removal step is preferably a step of reducing the concentration of polymer α in the water containing polymer α to 50% or less with respect to the concentration before the removal step. More preferably, it is 40% or less, still more preferably 30% or less, particularly preferably 20% or less, and most preferably 10% or less. The removal step is also preferably a step of reducing the concentration of polymer α in the treated water to 250 ppm or less. More preferably, it is 200 ppm or less, still more preferably 100 ppm or less, still more preferably 80 ppm or less, particularly preferably 60 ppm or less, and most preferably 50 ppm or less.

[0283] The polymer α is not particularly limited, and a water-soluble or water-insoluble polymer can be used which is a polymer in which the ratio of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms is 50% or more, and which contains an ionic group and has an ion exchange rate of 53 or less among the above-described polymers (I), or a polymer in which the ratio of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms is 50% or more and which contains an ionic group and has an ion exchange rate of 53 or less other than the above-described polymers (I) can also be used.

[0284] As the polymer α, for example, the following general formula (I): CX 1 X 3 =CX 2 R(-CZ 1 Z 2 -A 0 ) m (I) (In the formula, X 1 and X 3 are each independently F, Cl, H or CF3; X 2 is H, F, an alkyl group or a fluorine-containing alkyl group; A 0 is an anionic group; R is a linking group; Z 1 and Z 2 are each independently H, F, an alkyl group or a fluorine-containing alkyl group; and m is an integer of 1 or more.) Water-soluble or water-insoluble polymers containing a polymerized unit (I) based on the monomer represented by In the above polymer α, the content of the above polymerized unit (I) is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 99% by mass or more.

[0285] The above polymer α may contain a polymerized unit based on a fluorine-containing monomer such as trifluoroethylene, tetrafluoroethylene (TFE), vinylidene fluoride (VdF), vinyl fluoride (VF), chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), hexafluoroisobutylene, perfluoroalkyl ethylene, fluorovinyl ether (FVE), CH2 = CFCF3, CHF = CHCF3 (E isomer), CHF = CHCF3 (Z isomer), etc.

[0286] The above polymer α may also contain a polymerized unit based on a non-fluorine-containing monomer. The non-fluorine-containing monomer may be any monomer having a radically polymerizable ethylenically unsaturated bond. For example, acrylic acid esters, methacrylic acid esters, unsaturated carboxylic acids, hydrolyzable silyl group-containing monomers, hydroxyl group-containing alkyl vinyl ethers, carboxylic acid vinyl esters, α-olefins, etc. may be mentioned. Among the above non-fluorine-containing monomers, at least one selected from the group consisting of acrylic acid esters, methacrylic acid esters, unsaturated carboxylic acids, and hydrolyzable silyl group-containing monomers is preferable. Furthermore, as the non-fluorine-containing monomer, at least one monomer selected from the group consisting of at least one monomer selected from the group consisting of acrylic acid esters and methacrylic acid esters, unsaturated carboxylic acids, and hydrolyzable silyl group-containing monomers is more preferable. In addition, monomers having a radically polymerizable ethylenically unsaturated bond may be used in combination. As the above non-fluorine-containing monomer, those described in the above water-soluble polymer can be used.

[0287] The number average molecular weight of the above polymer α is 0.1×10 4 or more, preferably 0.2×10 4 or more, more preferably 0.3×10 4 or more, still more preferably 0.4×10 4 or more, particularly preferably 0.5×10 4 or more, even more preferably 1.0×10 4 or more, particularly preferably 3.0×10 4 or more, even more particularly preferably 3.1×10 4 or more, most preferably. Also, 75.0×10 4 or less is preferable, 50.0×10 4 or less is more preferable, 40.0×10 4 or less is still more preferable, 30.0×10 4 or less is still more preferable, 20.0×10 4 or less is particularly preferable. The weight average molecular weight of the above polymer α is 0.2×10 4 or more, preferably 0.4×10 4 or more, more preferably 0.6×10 4 or more, still more preferably 0.8×10 4 or more, even more preferably 1.0×10 4 or more, particularly preferably 5.0×10 4 or more, more particularly preferably 10.0×10 4 or more, even more particularly preferably 15.0×10 4 or more, even more preferably 20.0×10 4 or more, even more particularly preferably 25.0×10 4 or more, most preferably. Also, 150.0×10 4 or less is preferable, 100.0×10 4 or less is more preferable, 60.0×10 4 or less is still more preferable, 50.0×10 4 or less is particularly preferable, 40.0×10 4 or less is even more preferable. The number average molecular weight and the weight average molecular weight are values obtained by calculating the molecular weight using gel permeation chromatography (GPC) with monodisperse polystyrene as a standard. When measurement by GPC is not possible, the number average molecular weight of the water-soluble polymer can be determined based on the correlation between the number average molecular weight calculated from the number of terminal groups obtained by NMR, FT-IR, etc. and the melt flow rate. The melt flow rate can be measured in accordance with JIS K 7210.

[0288] Polymer α preferably has water solubility. Water solubility means the property of being easily dissolved or dispersed in water. For a water-soluble polymer α, for example, the particle size cannot be measured by dynamic light scattering (DLS). On the other hand, for a polymer α having water insolubility, for example, the particle size can be measured by dynamic light scattering (DLS). The above polymer α has an ion exchange rate (IXR) of 53 or less. The above IXR is preferably 0.5 or more, more preferably 1 or more, still more preferably 3 or more, even more preferably 4 or more, particularly preferably 5 or more, and especially preferably 8 or more. Also, the IXR is more preferably 43 or less, still more preferably 33 or less, and particularly preferably 23 or less. In the above polymer α, the ionic groups are typically distributed along the polymer main chain. The above polymer α includes the polymer main chain together with the repeating side chains bonded to this main chain, and preferably these side chains have ionic groups. Polymer α preferably contains an ionic group having a pKa of less than 10, more preferably less than 7. The ionic groups of polymer α are preferably selected from the group consisting of sulfonates, carboxylates, phosphonates, phosphates, and mixtures thereof. The terms "sulfonate, carboxylate, phosphonate, and phosphate" are intended to refer to their respective salts or the respective acids capable of forming salts. When a salt is used, preferably the salt is an alkali metal salt or an ammonium salt. A preferred ionic group is the sulfonate group.

[0289] In the water containing the above polymer α, the content of the polymer α is not particularly limited. For example, from the viewpoint of enhancing the removal efficiency, it is preferably 10% by mass or less. In the water containing the above polymer α, the content of the polymer α is more preferably 1% by mass or less, still more preferably 0.5% by mass or less, and particularly preferably 0.2% by mass or less. Also, it may be more than 0% by mass, may be more than 0.005% by mass, may be more than 0.006% by mass, may be more than 0.008% by mass, may be 0.010% by mass or more, may be more than 0.020% by mass, may be more than 0.025% by mass, or may be 0.1% by mass or more. The content of the above polymer α can be measured, for example, by solid-state NMR. The water containing the above polymer α may contain one single polymer α or may contain two or more different polymers α.

[0290] The water containing the above polymer α may contain substances other than the polymer α and water, and may be a dispersion, an aqueous solution, or the like. Examples of substances other than the polymer α and water include non-fluoropolymers, fluoropolymers other than the polymer α, oligomers, and the like. The fluoropolymer other than the polymer α is a fluoropolymer in which the ratio of hydrogen atoms bonded to carbon atoms substituted by fluorine atoms is less than 50%, which does not contain an ionic group, or which has an ion exchange rate higher than 53. Examples of the fluoropolymer other than the polymer α include fluoropolymers having an ion exchange rate (IXR) higher than 53. Preferred fluoropolymers other than the polymer α have no ionic groups at all or have a limited number of ionic groups that result in an ion exchange rate higher than about 100. The ion exchange rate of the preferred fluoropolymers other than the polymer α is preferably 1000 or more, more preferably 2000 or more, and still more preferably 5000 or more. Specific examples of the fluorine-containing polymer other than the polymer α include those among the fluorine-containing polymers described in the first treatment method of the present disclosure in which the proportion of hydrogen atoms bonded to carbon atoms replaced by fluorine atoms is less than 50%, those containing no ionic groups, or those having an ion exchange rate (IXR) higher than 53. For example, PTFE, TFE, and a copolymer of TFE and another monomer copolymerizable with TFE (fluorine-containing monomers such as vinylidene fluoride, hexafluoropropylene, chlorotrifluoroethylene, perfluoro(alkyl vinyl ether), etc., hydrocarbon olefins such as ethylene, propylene, isobutene, etc., alkyl vinyl ether, etc.) (for example, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), etc.), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), and fluororesins such as ethylene-chlorotrifluoroethylene (ECTFE), vinylidene fluoride-based rubbers such as vinylidene fluoride-hexafluoropropylene copolymer (FKM), fluorine rubbers such as tetrafluoroethylene-propylene rubber (FEPM) and tetrafluoroethylene-perfluoromethyl vinyl ether rubber (FFKM), and fluorine-containing elastomers, etc. can be mentioned. The above PTFE may be a homopolymer of TFE or a modified PTFE containing 99.0% by mass or more of TFE and 1.0% by weight or less of a modified monomer. As the fluorine-containing polymer other than the polymer α, at least one selected from the group consisting of PTFE and a melt-processable fluororesin containing 60.0 to 98.0% by mass of TFE units and 2.0 to 40.0% by mass of other monomers is preferable, and PTFE is more preferable.

[0291] In the water containing the polymer α, the content of substances other than the polymer α and water is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, and still more preferably 0.2% by mass or less. The lower limit of the content of substances other than the polymer α and water is not limited, but may be, for example, 0% by mass or 0.1% by mass. The water containing the above polymer α preferably has a water content of 99.0% by mass or more. More preferably, it is 99.5% by mass or more, and still more preferably, it is 99.8% by mass or more.

[0292] The present disclosure also provides a composition (hereinafter also referred to as "the fifth composition of the present disclosure") comprising a polymer in which 50% or more of the hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms, containing an ionic group and having an ion exchange rate of 53 or less, water, and a fluorine-containing polymer (excluding the above polymer), wherein the content of the polymer is 250 ppm or less.

[0293] In the fifth composition of the present disclosure, the polymer (polymer α) in which 50% or more of the hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms, containing an ionic group and having an ion exchange rate of 53 or less is the same as that described in the third treatment method of the present disclosure, and appropriate preferred embodiments can be adopted as appropriate. The fifth composition of the present disclosure may be an aqueous solution of polymer α or a dispersion of polymer α.

[0294] In the fifth composition of the present disclosure, the content of polymer α is 250 ppm or less based on the mass of the composition. The content of polymer α is preferably 200 ppm or less, more preferably 150 ppm or less, still more preferably 100 ppm or less, still more preferably 50 ppm or less, particularly preferably 25 ppm or less, and especially preferably 10 ppm or less. The lower limit of the above content is not particularly limited, but preferably 0.1 ppm or more, more preferably 0.5 ppm or more, still more preferably 1 ppm or more, still more preferably 2 ppm or more, and particularly preferably 5 ppm or more. The content of polymer α contained in the fifth composition of the present disclosure can be measured in the same manner as the water containing polymer α. For example, it is determined by solid NMR measurement. The fifth composition of the present disclosure may contain one kind of single polymer α or two or more different polymers α.

[0295] The water containing the polymer α contains a fluorine-containing polymer other than the polymer α. As the fluorine-containing polymer other than the polymer α, those described in the third treatment method of the present disclosure can be appropriately adopted, and appropriate preferred embodiments can be adopted. The ion exchange rate of the fluorine-containing polymer other than the polymer α is preferably more than 53, more preferably 100 or more, still more preferably 1000 or more, particularly preferably 2000 or more, and particularly preferably 5000 or more. As the fluorine-containing polymer other than the polymer α, PTFE is preferred.

[0296] In the fifth composition of the present disclosure, the content of the fluorine-containing polymer other than the polymer α is preferably 5000 ppm or less, more preferably 2000 ppm or less, still more preferably 1000 ppm or less, and particularly preferably 500 ppm or less, based on the mass of the composition. The lower limit of the above content is not particularly limited, but may be substantially 0 ppm, may be more than 0 ppm, may be 1 ppm or more, or may be 100 ppm or more. The content of the fluorine-containing polymer other than the polymer α can be determined by a method of separating the solid component (fluorine-containing polymer other than the polymer α) with an MF membrane.

[0297] The fifth composition of the present disclosure may contain substances other than the polymer α, water, and the fluorine-containing polymer other than the polymer α. For example, it may contain a flocculant or the like described in the third treatment method of the present disclosure. Further, the fifth composition of the present disclosure may contain metal ions, or may contain divalent or higher metal ions. As the divalent or higher metal ions, those contained in the second composition of the present disclosure can be appropriately contained. The content of metal ions with a valence of 2 or higher is preferably 0.05 mg / L or more, more preferably 0.1 mg / L or more, still more preferably 0.15 mg / L or more, and particularly preferably 0.2 mg / L or more, based on the composition. Also, the content of metal ions with a valence of 2 or higher is preferably 1000 mg / L or less, more preferably 500 mg / L or less, still more preferably 250 mg / L or less, even more preferably 100 mg / L or less, particularly preferably 50 mg / L or less, and most preferably 10 mg / L or less.

[0298] In the fifth composition of the present disclosure, the total amount of polymer α, water, and the fluorine-containing polymer other than polymer α is preferably 95.0% by mass or more, more preferably 99.0% by mass or more, still more preferably 99.9% by mass or more, and particularly preferably consisting essentially of only polymer α, water, and the fluorine-containing polymer other than polymer α.

[0299] The fifth composition of the present disclosure can be obtained by removing polymer α from the water containing polymer α described in the third treatment method of the present disclosure. As the above-mentioned removal method, the embodiments described in the third treatment method of the present disclosure can be appropriately adopted. In particular, as the removal step, a method that causes aggregation in polymer α and adopts the step of adding an inorganic flocculant to the water containing polymer α can preferably obtain the fifth composition of the present disclosure.

[0300] The present disclosure also provides a composition (hereinafter also referred to as "the sixth composition of the present disclosure") containing a polymer in which the ratio of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms is 50% or more, contains an ionic group, and has an ion exchange rate of 53 or less, water, and metal ions with a valence of 2 or higher, wherein the content of the polymer is 250 ppm or less.

[0301] In the sixth composition of the present disclosure, the polymer (polymer α) in which the ratio of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms is 50% or more, contains an ionic group, and has an ion exchange rate of 53 or less is the same as that described in the third treatment method of the present disclosure, and appropriate preferred embodiments can be adopted as appropriate. The sixth composition of the present disclosure may be an aqueous solution of a polymer or a dispersion of a polymer.

[0302] In the sixth composition of the present disclosure, the content of polymer α is 250 ppm or less based on the mass of the composition. The content of polymer α is preferably 200 ppm or less, more preferably 150 ppm or less, still more preferably 100 ppm or less, still more preferably 50 ppm or less, particularly preferably 25 ppm or less, and particularly preferably 10 ppm or less. The lower limit of the above content is not particularly limited, but is preferably 0.1 ppm or more, more preferably 0.5 ppm or more, still more preferably 1 ppm or more, still more preferably 2 ppm or more, and particularly preferably 5 ppm or more. The content of polymer α contained in the sixth composition of the present disclosure can be measured in the same manner as the water containing polymer α. For example, it is determined by solid NMR measurement. The sixth composition of the present disclosure may contain one single polymer α or two or more different polymer αs.

[0303] The sixth composition of the present disclosure contains divalent or higher metal ions. The divalent or higher metal ions are not particularly limited, but are preferably, for example, ions of the metals constituting the metal salts described as the above-mentioned inorganic flocculants, and at least one selected from the group consisting of Fe, Al, and Ca is preferable. In the sixth composition of the present disclosure, the content of the divalent or higher metal ions is preferably 0.05 mg / L or more based on the composition. More preferably, it is 0.1 mg / L or more, still more preferably 0.15 mg / L or more, and particularly preferably 0.2 mg / L or more. Further, the content of the divalent or higher metal ions is preferably 1000 mg / L or less, more preferably 500 mg / L or less, still more preferably 250 mg / L or less, even more preferably 100 mg / L or less, particularly preferably 50 mg / L or less, and most preferably 10 mg / L or less. The content of the divalent or higher metal ions is measured by the method of a pack test (manufactured by Kyoritsu Chemical-Check Laboratory Co., Ltd.).

[0304] The sixth composition of the present disclosure may contain a polymer α, water, and substances other than divalent or higher metal ions. For example, it may contain a flocculant or the like described in the third treatment method of the present disclosure. Further, the sixth composition of the present disclosure may contain a fluorine-containing polymer other than the polymer α. As the fluorine-containing polymer other than the polymer α, those described in the third treatment method of the present disclosure can be appropriately adopted. As the fluorine-containing polymer other than the polymer α, a fluorine-containing polymer having an ion exchange rate (IXR) higher than 53 is preferable. Further, the fourth composition of the present disclosure may contain PTFE. As the above PTFE, those described in the third treatment method of the present disclosure can be appropriately adopted. In the sixth composition of the present disclosure, the content of the fluorine-containing polymer other than the polymer α is preferably 5000 ppm or less based on the mass of the composition. More preferably, it is 2000 ppm or less, still more preferably 1000 ppm or less, and particularly preferably 500 ppm or less. The lower limit value of the above content is not particularly limited, but it may be substantially 0 ppm, may be more than 0 ppm, may be 1 ppm or more, or may be 100 ppm or more. The content of the fluorine-containing polymer other than the polymer α can be determined by a method of separating the solid component (fluorine-containing polymer other than the polymer α) with an MF membrane.

[0305] In the sixth composition of the present disclosure, the total amount of polymer α, water, and divalent or higher metal ions is preferably 95.0% by mass or more, more preferably 99.0% by mass or more, still more preferably 99.9% by mass or more, and particularly preferably consisting essentially of only polymer α, water, and divalent or higher metal ions.

[0306] The sixth composition of the present disclosure can be obtained by removing polymer α from water containing polymer α described in the third treatment method of the present disclosure. As the above removal method, the embodiments described in the third treatment method of the present disclosure described above can be appropriately adopted. In particular, as the removal step, one that causes aggregation in polymer α, and the sixth composition of the present disclosure can be preferably obtained by a method that employs a step of adding an inorganic flocculant (preferably a metal salt) to the water containing the polymer α.

Examples

[0307] Next, the present disclosure will be described with reference to experimental examples, but the present disclosure is not limited to such experimental examples only.

[0308] In the following experimental examples, the following formula: CH2=CF(CF2OCFCF3COOH) A homopolymer of the monomer represented by (number average molecular weight 90,000, weight average molecular weight 190,000) (hereinafter referred to as "polymer A") was used. The above number average molecular weight and weight average molecular weight were measured by gel permeation chromatography (GPC) using GPC HLC-8020 manufactured by Tosoh Corporation, using columns manufactured by Shodex (one GPC KF-801, one GPC KF-802, and two GPC KF-806M connected in series), flowing tetrahydrofuran (THF) as a solvent at a flow rate of 1 ml / min, and calculating the molecular weight using monodisperse polystyrene as a standard.

[0309] Each numerical value in the experimental examples was measured by the following method.

[0310] Content of polymer A in the treated aqueous solution The content of polymer A in the treated aqueous solution was measured by the following method.

[0311] Preparation of calibration curve of polymer A An aqueous solution containing sodium trifluoroacetate and polymer A with known concentrations was adjusted to 5 levels, 19 and 19F NMR measurement was performed. From the concentrations of sodium trifluoroacetate and polymer A in each sample and the peak area values of sodium trifluoroacetate and polymer A, a was determined using linear approximation according to the following relational expression (1). A = a×5×B×W×136.00 / (3×X×256.08) (1) A: Peak area value of CF2 and CF3 derived from polymer A (δ F ppm: -78 to -88 (-CF-CF2-O-, >CF-CF3)) W: Concentration of polymer A (ppm) B: Peak area value of trifluoroacetic acid (δ F ppm: -76 (CF3-)) X: Concentration of trifluoroacetic acid (ppm) The chemical shift used was the value when the peak of CF3 derived from sodium trifluoroacetate was set to -76.0 ppm.

[0312] The treated aqueous solution was concentrated using an evaporator. Sodium trifluoroacetate was added to the concentrated treated aqueous solution, 19 and 19F NMR measurement was performed. From the concentration of sodium trifluoroacetate in the measurement sample and the peak area values of sodium trifluoroacetate and polymer A, the content of polymer A in the treated aqueous solution was determined according to the following relational expression (2). Y = 3×C×Z×P×256.08 / (a×5×D×Q×136.00) (2) C: Peak area value of polymer A (δ F ppm: -78 to -88 (-CF-CF2-O-, >CF-CF3)) Y: Content of polymer A in the treated aqueous solution (ppm) D: Peak area value of trifluoroacetic acid (δ F ppm: -76 (CF3-)) Z: Concentration of trifluoroacetic acid (ppm) P: Mass of the treated aqueous solution before concentration (g) Q: Mass (g) of the post-treatment aqueous solution The chemical shift was the value when the peak derived from CF3 of sodium trifluoroacetate was set to -76.0 ppm.

[0313] pH Measured with a pH meter D-20 manufactured by Horiba.

[0314] Dissolved aluminum concentration in the treated aqueous solution Measured using a simple water quality analysis product, Pack Test Aluminum (manufactured by Kyoritsu Chemical-Check Lab., Ltd., model WAK-AI, measurement limit 0.05 mg / L).

[0315] Example 1 As a model aqueous solution, 0.37 g of a 26.8 mass% aluminum sulfate aqueous solution was added to 100 g of an aqueous solution containing 500 ppm of polymer A (aqueous solution A). The polymer A-containing aqueous solution (aqueous solution A) was stirred in a container at a temperature of 25 °C for 30 minutes. After stirring, the pH was 3.2. An NaOH aqueous solution (25%) was added to the polymer A-containing aqueous solution (aqueous solution A) as a pH adjuster to adjust the pH to 7.3. To the aqueous solution after pH adjustment, 0.34 g of a 0.07 mass% aqueous solution of partially hydrolyzed polyacrylamide (trade name: Floclan A1210, manufactured by Katayama Nalco Co., Ltd.) was added. When stirred at a temperature of 25 °C for 30 minutes, aluminum precipitates were precipitated. The precipitated aluminum precipitates were filtered with filter paper to obtain a treated aqueous solution. The concentration of polymer A in the obtained treated aqueous solution was 42 ppm. The dissolved aluminum concentration in the obtained treated aqueous solution was 1 mg / L.

[0316] Example 2 A treated aqueous solution was obtained in the same manner as in Experimental Example 1, except that the addition amount of the aluminum sulfate aqueous solution was changed to 0.05 g, the pH before pH adjustment was changed to 2.9, and the pH after pH adjustment was changed to 6.8. The concentration of polymer A in the obtained treated aqueous solution was 90 ppm. The dissolved aluminum concentration in the obtained treated aqueous solution was 0.5 mg / L.

Claims

1. The ratio of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms is 50% or more, and the number average molecular weight is 1.0 × 10 ４ or more, comprising a polymer having the property of being soluble or dispersible in water, water, and a fluorine-containing polymer (excluding said polymer) having an ion exchange rate higher than 53, and the content of said polymer is 250 ppm or less.

2. The ratio of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms is 50% or more, and the number average molecular weight is 1.0 × 10 ４ and 20.0 × 10 4 or less, and comprising a polymer containing an anionic group, water, and a fluorine-containing polymer (excluding said polymer) having an ion exchange rate higher than 53, wherein the content of said polymer is 250 ppm or less.

3. 3. The composition according to claim 1, wherein the fluorine-containing polymer is polytetrafluoroethylene.

4. 4. The composition according to claim 1, wherein the content of the fluorine-containing polymer is 1 to 5,000 ppm.

5. The composition according to any one of claims 1 to 4, further comprising a divalent or higher metal ion, wherein the divalent or higher metal ion is an ion of at least one metal selected from the group consisting of Fe, Al, and Ca.

6. 6. The composition according to claim 5, wherein the content of divalent or higher valent metal ions is 0.05 to 1000 mg / L.

7. The ratio of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms is 50% or more, and the number average molecular weight is 1.0 × 10 ４ a polymer having the property of being soluble or dispersible in water, water, and divalent or higher metal ions, wherein the polymer content is 250 ppm or less, and the divalent or higher metal ions are ions of at least one metal selected from the group consisting of Fe, Al, and Ca.

8. The ratio of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms is 50% or more, and the number average molecular weight is 1.0 × 10 ４ a polymer having an anionic group-containing molecular weight of not less than 20.0 x 10 4 and not more than 20.0 x 10 4 , water, and a divalent or higher metal ion, wherein the polymer content is not more than 250 ppm, and the divalent or higher metal ion is an ion of at least one metal selected from the group consisting of Fe, Al, and Ca.

9. 9. The composition according to claim 7, wherein the content of divalent or higher valent metal ions is 0.05 to 1000 mg / L.

10. The ratio of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms is 50% or more, and the number average molecular weight is 1.0 × 10 ４ The water treatment method is characterized in that it comprises a step of removing a polymer from water containing the polymer, the polymer having the property of being soluble or dispersible in water, and the step is a step of flocculating the water containing the polymer by adding an inorganic flocculant and a polymer flocculant to the water containing the polymer.

11. The ratio of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms is 50% or more, and the number average molecular weight is 1.0 × 10 ４ a step of removing a polymer from water containing a polymer having a molecular weight of not less than 20.0 × 10 4 and containing an anionic group, the step comprising adding an inorganic flocculant and a polymer flocculant to the water containing the polymer to flocculate the water containing the polymer.