JP2015083299A - Porous polymer membrane and method of producing porous polymer membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a porous polymer membrane which can be used for water treatment obtained without using compounds conventionally used as a hydrophilizing agent for a hydrophobic polymer in the production of a water treatment film.SOLUTION: A porous polymer membrane comprises a fluoropolymer (A) having a vinylidene fluoride unit, and a polymer (B) having a polymerization unit derived from a specific monomer (a) and a polymerization unit derived from a specific monomer (b).

Description

The present invention relates to a polymer porous membrane and a method for producing a polymer porous membrane.

In recent years, porous membranes have been used in various fields such as water treatment fields such as water purification and wastewater treatment, medical applications such as blood purification, food industry fields, etc., as well as charged membranes, battery separators, and fuel cells. Yes.

For example, in the field of water treatment, porous membranes have come to be used as water treatment membranes in order to replace conventional sand filtration and coagulation sedimentation processes and improve the quality of treated water. In such a water treatment field, since the amount of treated water is large, the polymer porous membrane is required to have excellent water permeability. If the water permeation performance is excellent, the membrane area can be reduced, so the water purifier becomes compact and the equipment cost can be reduced.

Further, in the water purification treatment, the membrane may be washed with an alkaline solution or the like for chemical cleaning of the membrane, and the polymer porous membrane is required to have chemical resistance. In recent years, porous membranes using fluoropolymers such as polyvinylidene fluoride resin as a highly chemical-resistant material have been studied. However, since vinylidene fluoride resin is a hydrophobic polymer, it is included in treated water during the treatment process. The problem is that solid substances and dissolved components that adhere to the membrane become difficult to remove (fouling), and it has been studied to hydrophilize the fluoropolymer to form a water treatment membrane.

Examples of hydrophobizing the hydrophobic polymer to form a water treatment membrane include, for example, hydrophilization containing a hydrolyzate decomposition product that generates a hydrophilic chemical species by a decomposition reaction and a polyvinylidene fluoride resin. A porous membrane (for example, refer to Patent Document 1), a semipermeable membrane for water treatment (for example, containing cellulose acetate and polyvinylidene fluoride, and the content ratio of polyvinylidene fluoride in all polymer components is 5 to 60% by mass (for example, , Patent Document 2) Caustic resistance comprising a homogeneous polymer blend comprising 50 to 99 weight percent of at least one polyvinylidene fluoride (PVDF) polymer or copolymer and 1 to 50 weight percent of at least one acrylic polymer. A film (see, for example, Patent Document 3), a polyvinylidene fluoride resin, an acrylic ester polymer having a main chain, and Or a porous film composed mainly of a mixture of a methacrylic acid ester-based polymer and a graft copolymer whose side chain is an ethylene oxide-based polymer and / or a propylene oxide-based polymer, A porous film having a degree of polymerization of 25 or less and the side chain contained in the graft copolymer by 55% by weight or more (for example, see Patent Document 4) is disclosed.
Also, a polyvinylidene fluoride resin, a polyacrylate resin and / or a polymethacrylate resin, a porous film containing a polyvinylpyrrolidone resin, a polyvinylidene fluoride resin, and an acrylate ester There has been disclosed a porous membrane containing a monomer and / or a methacrylate-based monomer and a copolymer mainly composed of vinylpyrrolidone (see, for example, Patent Document 5).

Japanese Patent Application Laid-Open No. 2005-296846 JP 2006-326497 A Special table 2010-526885 gazette JP 2007-723 A JP 2006-205067 A

An object of the present invention is to provide a polymer porous membrane that can be used for water treatment obtained without using a compound that has been conventionally used as a hydrophilizing agent for a hydrophobic polymer in the production of a water treatment membrane. To do.

The inventors of the present invention have found that the above-mentioned problem can be solved by making the polymer porous membrane a fluoropolymer having a vinylidene fluoride unit and a polymer having a specific polymerization unit. The invention has been reached.

That is, the present invention relates to a fluoropolymer (A) having a vinylidene fluoride unit and the following general formula (1):

(In the formula, R represents a hydrogen atom or a methyl group. Rf represents a fluorinated alkyl group having 1 to 25 carbon atoms.) The polymer unit derived from the monomer (a) represented by: General formula (2):

(In the formula, R represents a hydrogen atom or a methyl group. R ₁ represents an alkylene group having 1 to 10 carbon atoms. R ₂ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a carbon number. 1 represents a group in which at least one hydrogen atom of the alkyl group is substituted with a hydroxyl group, m represents an integer of 0 to 200. However, when m = 0, R ₂ represents a hydrogen atom or carbon. And a polymer (B) having a polymer unit derived from the monomer (b) represented by the formula (1), wherein one or more hydrogen atoms of the alkyl group are substituted with a hydroxyl group. It is a polymer porous membrane.

The polymer porous membrane of the present invention includes a fluoropolymer (A) having a vinylidene fluoride unit and the following general formula (1):

(In the formula, R represents a hydrogen atom or a methyl group. Rf represents a fluorinated alkyl group having 1 to 10 carbon atoms.) The polymer unit derived from the monomer (a) represented by: General formula (2):

(In the formula, R represents a hydrogen atom or a methyl group. R ₁ represents an alkylene group having 1 to 10 carbon atoms. R ₂ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. And a polymer (B) having a polymerization unit derived from the monomer (b) represented by the formula (1).

It is preferable that the said polymer (B) is 0.01-40 mass% with respect to a fluoropolymer (A).

The polymer (B) may be a random polymer composed of a segment composed of polymerized units derived from the monomer (a) and a segment composed of polymerized units derived from the monomer (b), or a block polymer. Although it may be, it is preferably a block polymer.

The polymer (B) preferably has a weight average molecular weight of 1,000 to 2,000,000.

The polymer porous membrane is preferably a hollow fiber membrane. The polymer porous membrane is also preferably a flat membrane. Furthermore, the polymer porous membrane is preferably used for water treatment.

Since the porous polymer membrane of the present invention has the above-described configuration, a water treatment membrane is produced without using a compound that has been conventionally used as a hydrophilizing agent for a hydrophobic polymer in the production of a water treatment membrane. It is something that can be done.

The present invention is described in detail below.

The polymer porous membrane of the present invention comprises a fluoropolymer (A) having a vinylidene fluoride unit, a polymer unit derived from the monomer (a) represented by the general formula (1), and the general formula (2). And the polymer (B) having a polymer unit derived from the monomer (b) represented by the formula (B), which can hydrophilize the fluoropolymer (A). .

The content of the polymer (B) in the polymer porous membrane is preferably 0.01 to 40% by mass with respect to the fluoropolymer (A). Thus, in the present invention, the fluoropolymer (A) can be hydrophilized even if the content of the polymer (B) in the polymer porous membrane is small as in the above range. The content of the polymer (B) in the polymer porous membrane is more preferably 0.05 to 30% by mass and further 0.10 to 25% by mass with respect to the fluoropolymer (A). preferable.

The fluoropolymer (A) having a vinylidene fluoride unit has at least a constituent unit derived from vinylidene fluoride in the constituent unit, and is a polyvinylidene fluoride or a copolymer having a vinylidene fluoride unit.

The above-mentioned polyvinylidene fluoride may be in a form further having other structural units in addition to the form in which all the structural units are vinylidene fluoride units, but the proportion of the vinylidene fluoride units in all the structural units is 90 mol% Is preferably exceeded. More preferably, it is 92 mol% or more, More preferably, it is 95 mol% or more.

Other structural units that may be contained in the polyvinylidene fluoride include hexafluoropropylene units, chlorotrifluoroethylene units, perfluorovinyl ether units, vinyl alcohol units, vinyl ester monomer units, and unsaturated carboxylic ester monomer units. Etc.

The weight average molecular weight of the polyvinylidene fluoride is preferably 30,000 to 2,000,000, and more preferably 50,000 to 1,000,000 from the viewpoint of mechanical strength and workability of the polymer porous membrane.
The weight average molecular weight can be determined by gel permeation chromatography (GPC).

Examples of the copolymer having a vinylidene fluoride unit include a vinylidene fluoride / tetrafluoroethylene copolymer and a vinylidene fluoride / hexafluoropropylene copolymer. From the viewpoint of mechanical strength and alkali resistance, the copolymer having a vinylidene fluoride unit is particularly preferably a vinylidene fluoride / tetrafluoroethylene copolymer.

From the viewpoint of film formability and alkali resistance, the vinylidene fluoride / tetrafluoroethylene copolymer has a molar ratio of vinylidene fluoride units and tetrafluoroethylene units (vinylidene fluoride units / tetrafluoroethylene units) of 50 to 99 / It is preferable that it is 50-1. Examples of such a polymer include Neoflon VT50, VP50, VT100, VP100, VP101, and VP100X manufactured by Daikin Industries, Ltd. The vinylidene fluoride / tetrafluoroethylene copolymer more preferably has a vinylidene fluoride unit / tetrafluoroethylene unit in a molar ratio of 50 to 90/50 to 10. In addition to vinylidene fluoride / tetrafluoroethylene copolymer consisting of only vinylidene fluoride units and tetrafluoroethylene units, vinylidene fluoride / tetrafluoroethylene copolymers include vinylidene fluoride units and tetrafluoroethylene units. In addition, a terpolymer having other structural units such as a hexafluoropropylene unit, a chlorotrifluoroethylene unit, a perfluorovinyl ether unit, a vinyl alcohol unit, and a vinyl ester monomer unit may be used as long as the characteristics are not impaired.
In addition, when the said vinylidene fluoride / tetrafluoroethylene copolymer further has other structural units in addition to the vinylidene fluoride units and tetrafluoroethylene units, the vinylidene fluoride units and tetrafluoroethylene units in all the structural units The total ratio is preferably 80 mol% or more, and more preferably 85 mol% or more. More preferably, it is 90 mol% or more.

The weight average molecular weight of the copolymer having a vinylidene fluoride unit is preferably 10,000 or more from the viewpoint of mechanical strength and film formability. More preferably, it is 50000-1 million, More preferably, it is 100000-900000.
The weight average molecular weight can be determined by gel permeation chromatography (GPC).

The said fluoropolymer (A) can be manufactured by the conventionally well-known method by which the structural monomer of the fluoropolymer (A) containing a vinylidene fluoride is normally performed, for example. For example, it can be produced by a polymerization method such as solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization or the like, but it is preferably produced by emulsion polymerization or suspension polymerization in terms of industrial implementation. In said superposition | polymerization, a polymerization initiator, surfactant, a chain transfer agent, and a solvent can be used and what is each normally used can be used, respectively.

The polymer (B) has the following general formula (1):

(In the formula, R represents a hydrogen atom or a methyl group. Rf represents a fluorinated alkyl group having 1 to 25 carbon atoms.) The polymer unit derived from the monomer (a) represented by: General formula (2):

(In the formula, R represents a hydrogen atom or a methyl group. R ₁ represents an alkylene group having 1 to 10 carbon atoms. R ₂ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a carbon number. 1 represents a group in which at least one hydrogen atom of the alkyl group is substituted with a hydroxyl group, m represents an integer of 0 to 200. However, when m = 0, R ₂ represents a hydrogen atom or carbon. The polymer (B) is a polymer having a polymer unit derived from the monomer (b) represented by the formula (1). As long as it has a polymer unit derived from the monomer (a) and a polymer unit derived from the monomer (b), it may have a polymer unit derived from another monomer (c).

The monomer (a) has the following general formula (1):

(In the formula, R represents a hydrogen atom or a methyl group. Rf represents a fluorinated alkyl group having 1 to 25 carbon atoms.) The carbon number of Rf in the formula is As, 1-12 are preferable, 1-10 are more preferable, 4-10 are still more preferable, and 6-10 are especially preferable.

As Rf in the general formula (1), for example,
Formula (3):
_{- (CH 2) n - (} CF 2) m -X (3)
(Where n is an integer from 1 to 20, m is an integer from 1 to 12, X represents hydrogen or fluorine, provided that m + n <26).
Formula (4):
_{- (CH 2) a - (} CF 2) b - (O- (CF 2) c) d (CF 2) e -X (4)
(Where a is an integer of 1 to 12, b is an integer of 0 to 12, c is an integer of 1 to 12, d is an integer of 1 to 25, e is an integer of 0 to 12, and X represents hydrogen or fluorine. (However, a + b + c × d + e <26.)
Etc.

Specifically, —CH ₂ —CF ₃ , —CH ₂ —CF ₂ CF ₃ , —CH ₂ —CF ₂ CF ₂ H, —CH ₂ —CF ₂ CF ₂ CF ₂ CF ₃ , —CH ₂ —CF ₂ CF ₂ CF ₂ CF ₂ H, —CH ₂ —CF ₂ —CFH—CF ₃ , —CH ₂ CH ₂ —CF ₂ CF ₂ CF ₂ CF ₃ , —CH ₂ CH ₂ — (CF ₂ ) ₆ —F, — _{CH 2 CH 2 - (CF 2} ) 8 -F, -CH 2 CH 2 - (CF 2) 2 -F, - (CH 2) 6 - (CF 2) 6 -F,

Etc.

Among these, perfluoroalkyl group-containing groups such as (CF ₂ ) _m —X are preferable, and (CF ₂ ) _m —F is more preferable. More preferred are a perfluorohexyl group, a perfluorobutyl group and a perfluoroethyl group, and a perfluorohexyl group and a perfluorobutyl group are particularly preferred.

As the monomer (a), specifically,

1 type, or 2 or more types, etc. are mentioned. Among these,

1 type or 2 types or more are preferable.

The monomer (b) has the following general formula (2):

(In the formula, R represents a hydrogen atom or a methyl group. R ₁ represents an alkylene group having 1 to 10 carbon atoms. R ₂ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a carbon number. 1 represents a group in which at least one hydrogen atom of the alkyl group is substituted with a hydroxyl group, m represents an integer of 0 to 200. However, when m = 0, R ₂ represents a hydrogen atom or carbon. Represents a group in which at least one hydrogen atom of the alkyl group of formula 1 to 10 is substituted with a hydroxyl group.

_{R 1} in the general formula (2) represents an alkylene group having 1 to 10 carbon atoms, thus, _{R 1} O is a represent an oxyalkylene group having 1 to 10 carbon atoms, the _R 1 O Examples thereof include one or more of oxyethylene group, oxypropylene group, oxybutylene group, oxypentylene group and the like. Among these, an oxyethylene group is preferable.

M in the said General formula (2) represents the repeating number of R < ₁ > O, and is an integer of 0-200. m is preferably 1 to 200, more preferably 1 to 100, and still more preferably 1 to 50.
In addition, when m is 2 or more, R ₁ O may be two or more different, and when R ₂ O contains two or more different oxyalkylene groups, their bonding positions are particularly limited. It may not be random, may be a block, or may be alternating.
R ₂ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a group in which one or more hydrogen atoms of an alkyl group having 1 to 10 carbon atoms are substituted with a hydroxyl group. R ₂ is preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. Since hydrophilicity is increased, it is preferable that the hydroxyl group is in the R _2. The number of hydroxyl groups substituted is not particularly limited, but one is preferable from the viewpoint of ease of synthesis and hydrophilicity. When R ₂ has a hydroxyl group, m is preferably 0.

As the monomer (b), specifically, as an alkyl group-terminated polyalkylene glycol mono (meth) acrylate,
Methoxypolyethylene glycol mono (meth) acrylate:
_{CH 2 = CR-COO- (C} 2 H 4 O) n -CH 3 n = 2~20,
Ethoxy polyethylene glycol mono (meth) acrylate, propoxy polyethylene glycol mono (meth) acrylate, butoxy polyethylene glycol mono (meth) acrylate, octoxy polyethylene glycol mono (meth) acrylate, lauroxy polyethylene glycol mono (meth) acrylate, stearoxy polyethylene Examples thereof include glycol mono (meth) acrylate and nonyl phenoxy polyethylene glycol mono (meth) acrylate. As a hydroxyl-terminated polyalkylene glycol mono (meth) acrylate,
Polyethylene glycol mono (meth) acrylate:
_{CH 2 = CR-COO- (C} 2 H 4 O) n -H n = 2~20,
Polypropylene glycol mono (meth) acrylate:
_{CH 2 = CR-COO- (C} 3 H 6 O) n -H n = 2~20,
Polyethylene glycol-polypropylene glycol mono (meth) acrylate:
_{CH 2 = CR-COO- (C} 2 H 4 O) n - (C 3 H 6 O) m -H n = 1~20, m = 1~20,
Poly (ethylene glycol-tetramethylene glycol) mono (meth) acrylate:
_{CH 2 = CR-COO- (C} 2 H 4 O) n - (C 4 H 8 O) m -H n = 1~20, m = 1~20,
Poly (propylene glycol-tetramethylene glycol) monomethacrylate:
_{CH 2 = CR-COO- (C} 3 H 6 O) n - (C 4 H 8 O) m -H n = 1~20, m = 1~20 , and the like.
Although overlapping with the above, ethoxy-diethylene glycol (meth) acrylate, methoxy-triethylene glycol (meth) acrylate, 2-ethylhexyl-diglycol (meth) acrylate, methoxy-polyethylene glycol (meth) acrylate, methoxydipropylene glycol ( (Meth) acrylates having oxyalkylene groups such as (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, phenoxy-polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate,

And hydroxyl group-containing (meth) acrylic acid esters. Among these, alkyl group-terminated polyalkylene glycol mono (meth) acrylates are preferable. Of these, methoxypolyethylene glycol mono (meth) acrylate is preferred. Examples of such monomers include NOF's Blemmer PME series, Blemmer AME series, Blemmer 50POEP-800B, Blemmer 50AOEP-800B, and the like.

As said other monomer (c), acrylic monomers other than (a) and (b), styrene, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl versatate, maleic anhydride , Maleic acid, maleic acid ester and the like.

The content of each polymer unit in the polymer (B) is preferably, for example, in the following range.

The content of the polymerized units derived from the monomer (a) is preferably 1 to 80 mol% with respect to the total polymerized units of the polymer (B). More preferably, it is 20-70 mol%.

The content of the polymerized units derived from the monomer (b) is preferably 1 to 80 mol% with respect to all polymerized units of the polymer (B). More preferably, it is 20-70 mol%.

The polymer unit derived from the monomer (c) is an optional component, but when the polymer (B) has a polymer unit derived from the monomer (c), the content of the polymer unit is that of the polymer (B). It is preferable that it is 0-60 mol% with respect to all the polymerization units. More preferably, it is 0-30 mol%.

The content of each polymer unit in the polymer (B) is selected so that the total amount is 100 mol% within the range of the content of each polymer unit described above.

The polymer (B) may be a random polymer or a block polymer composed of a segment composed of polymerized units derived from the monomer (a) and a segment composed of polymerized units derived from the monomer (b). A block polymer is preferred. By using such a block polymer as the polymer (B), the compatibility of the copolymer (B) with the fluoropolymer (A) can be improved, and the outflow of the copolymer (B) when the polymer porous membrane is used. Can be further suppressed.
Such a block polymer is a novel compound.

The block polymer is a polymer obtained by block polymerization of a segment composed of a polymer unit derived from the monomer (a) and a segment composed of a polymer unit derived from the monomer (b). Preferably there is. In the block polymer, the segment composed of polymerized units derived from the monomer (a) and the segment composed of polymerized units derived from the monomer (b) may be one by one, A plurality of both of them may be included.
The method for producing the block polymer will be described in detail later.

The polymer (B) preferably has a weight average molecular weight of 1,000 to 2,000,000. When the weight average molecular weight of the polymer (B) is in such a range, the compatibility with the fluoropolymer (A) having a vinylidene fluoride unit is high, and the effect of improving hydrophilicity is also high, which is preferable. More preferably, it is 3000-500000 as a weight average molecular weight of a polymer (B), More preferably, it is 5000-200000.
The weight average molecular weight can be determined by gel permeation chromatography (GPC).

As a method for producing the polymer (B), living radical polymerization, living anion polymerization and the like can be used in addition to ordinary radical polymerization and ionic polymerization. The composition of the polymer (B) can be controlled by using monomers having different reaction rates or adjusting the amount of monomers charged. Moreover, the target molecular weight can be obtained by adjusting the amount of the initiator and the reaction time. Furthermore, a block polymer can be obtained by adjusting the timing of monomer supply in living polymerization. Specifically, for example, a method in which an initiator and a monomer (a) are initially charged and polymerization is started, and then the monomer (b) is added when the monomer (a) is almost consumed, and then polymerization is performed. It is.

The block copolymer of the present invention is preferably produced by a living radical polymerization method.

The living radical polymerization is based on establishing rapid equilibrium between a small amount of growth radical (free radical) species and a large amount of dormant species in the growth reaction by applying heat, light, a metal catalyst, and the like. Various types of living radical polymerization have been proposed with dormant chains.

For example, ATRP method (atom transfer radical polymerization method) using alkyl halide as dormant, RAFT method (reversible addition fragment transfer) using thioester, NMP method (nitroxide polymerized polymerization) using alkoxyamine, and the like have been proposed.

The ATRP method (atom transfer radical polymerization method) is a method in which a vinyl monomer is polymerized using a highly reactive polymerization initiator having a carbon-halogen bond and a transition metal complex serving as a polymerization catalyst. -514479, Mitsuo Sawamoto et al., Macromolecules 1995, 28, 1721).

The RAFT method is a method in which a vinyl monomer is polymerized by adding a chain transfer agent having a high chain transfer constant called a rafting agent to a normal radical polymerization system (M.G. Moad et al., Macromolecules 1998, 31, 5559). A thioester can be used as a rafting agent.

The NMP method is a method in which alkoxyamine is thermally cleaved to generate stable nitroxides and polymer radicals, and polymer monomers are polymerized with vinyl monomers (M. K. Georges et al., Macromolecules 1993, 26, 2987). ). Under cleavage nitroxides react only with carbon-centered free radicals without initiating polymerization. The nitroxide and the polymer radical reacted with the monomer can be combined again and exist stably as a dormant. Living radical polymerization proceeds in the above process.

Any of the above-described methods may be used as the living radical polymerization in the present invention, and there is no particular limitation, but atom transfer radical polymerization is preferably used from the viewpoint of a wide selection range of raw materials.

Details of the atom transfer radical polymerization method will be described in detail below.

The polymerization initiator is not particularly limited as long as it is a compound having at least one chlorine atom, bromine atom, or iodine atom serving as a polymerization initiation point, but usually one chlorine atom or bromine atom serving as an initiation point. Or a compound with two is used.

Specifically, for example, benzyl halide, halogenated alkane, haloester, haloketone, halonitrile, sulfonyl halide and the like are used, and among these, benzyl halide is preferable because of easy availability of raw materials. Examples of benzyl halide include 1-phenylethyl chloride and 1-bromoethylbenzene. Examples of the halogenated alkane include chloroform and carbon tetrachloride.

Examples of haloesters include ethyl 2-bromoisobutyrate or ethyl 2-bromopropionate. Examples of haloketones include bromoacetone and bromoacetophenone. Examples of halonitriles include 2-bromopropionitrile. Examples of the sulfonyl halide include p-toluenesulfonyl chloride.

Although the usage-amount of a polymerization initiator is not specifically limited, As a density | concentration in a reaction system, it is 0.01-10 mol / liter normally, Preferably it is 0.10-5 mol / liter.

Although it does not restrict | limit especially as said transition metal complex, It is a metal complex which uses the transition metal (M) chosen from the periodic table group 11-11 as a central metal.

Specific examples of the transition metal (M) include, for example, Cu ⁰ , Cu ⁺ , Ni ⁰ , Ni ⁺ , Ni ²⁺ , Pd ⁰ , Pd ⁺ , Pt ⁰ , Pt ⁺ , Pt ²⁺ , Rh ⁺ , Rh ²⁺ , ^{Rh 3+, Co +, Co 2+} , Ir 0, Ir +, Ir 2+, Ir 3+, Fe 2+, Ru 2+, Ru 3+, Ru 4+, Ru 5+, Os 2+, Os 3+, Re 2+, Re 3+, Re 4+ , Re ⁶⁺ , Mn ²⁺ , Mn ³⁺ . Among these, Cu ⁺ , Ni ²⁺ , Fe ²⁺ , and Ru ²⁺ are preferable from the viewpoint of catalyst activity.

The metal compound used for a transition metal complex is illustrated. Examples of copper compounds having monovalent copper metal include cuprous chloride, cuprous bromide, cuprous iodide, cuprous cyanide, etc., and nickel compounds having divalent nickel include nickel dichloride. As iron compounds having divalent iron, such as nickel dibromide and nickel diiodide, ruthenium compounds having divalent ruthenium, such as iron dichloride, iron dibromide and iron diiodide, Examples include ruthenium chloride, ruthenium dibromide, and ruthenium diiodide.

It is preferable to coordinate an organic ligand to the transition metal (M) in terms of enabling solubilization in a polymerization solvent and reversible change of the redox conjugated complex to enhance the catalytic activity. Examples of the coordination atom to the metal include a nitrogen atom, an oxygen atom, a phosphorus atom, and a sulfur atom, and a nitrogen atom or a phosphorus atom is preferable. Specific examples of the organic ligand include 2,2′-bipyridyl and derivatives thereof, 1,10-phenanthroline and derivatives thereof, tetramethylethylenediamine, pentamethyldiethylenetriamine, tris (dimethylaminoethyl) amine, triphenylphosphine, And tributylphosphine. Although the usage-amount of an organic ligand is not specifically limited, It is 0.1-100 times amount normally with respect to a transition metal (M), Preferably it is 1-10 times amount.

Although the usage-amount of a transition metal (M) is not specifically limited, 0.01-100 mol normally with respect to 1 mol of polymerization start terminals of a polymerization initiator, Preferably it is 0.1-50 mol, More preferably, it is 0.1. -10 mol.

Atom transfer radical polymerization can be carried out in the absence of a solvent, but can also be carried out in the presence of a solvent. Examples of the solvent used as necessary include water; ethers such as diethyl ether, tetrahydrofuran, diphenyl ether, anisole and dimethoxybenzene; amides such as N, N-dimethylformamide and N, N-dimethylacetamide; acetonitrile, Nitriles such as propionitrile and benzonitrile; ester compounds or carbonate compounds such as acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, ethylene carbonate, propylene carbonate; methanol, ethanol, propanol, isopropanol, n-butyl alcohol Alcohols such as t-butyl alcohol and isoamyl alcohol; aromatic hydrocarbons such as benzene and toluene; chlorobenzene, methylene chloride, chloro Lum, chlorobenzene, halogenated hydrocarbons such as benzotrifluoride, and the like.

Although the usage-amount of a solvent is not specifically limited, It is 0.1-5000 weight part normally with respect to 100 weight part of monomer preparations, Preferably it is 1-2000 weight part, More preferably, it is 10-1000 weight part.

The atom transfer radical polymerization is usually performed at a temperature of -50 to 200 ° C, preferably 0 to 150 ° C, more preferably 20 to 130 ° C. There are no particular restrictions on the charging procedure of each substance, and any charging method may be used. However, the initiator is dissolved immediately before the polymerization temperature is raised to the polymerization temperature by dissolving substances other than the polymerization initiator and preparing a uniform solution. It is preferable to polymerize by charging.

It is generally industrially common to use the polymerization reaction solution as it is for the second block chain forming step (ii) after completion of the polymerization. However, if necessary, the first block chain may be separated from the polymerization reaction solution. For example, in accordance with a well-known method, residual monomer and solvent can be distilled off, reprecipitation in an appropriate solvent, filtration or centrifugation of the precipitated polymer, washing and drying of the polymer can be performed.
In addition, transition metal complexes and organic ligands used as catalysts by diluting the polymerization solution with a good solvent for the polymer, such as tetrahydrofuran (THF), toluene, etc., and passing through a column or pad of alumina, silica or clay Can be removed from the reaction solution. In addition, a method in which the transition metal and the organic ligand contained in the reaction solution are treated by an extraction operation such as liquid separation, or a method in which a metal adsorbent is dispersed in the reaction solution can be employed.

The obtained fluoropolymer can be prepared in any form such as emulsion, organic solvent solution, aerosol, etc. after being diluted or dispersed in water, organic solvent, etc. if necessary, and used for the preparation of polymeric porous membranes Is done.

In order to form a mixture with the fluoropolymer (A) having a vinylidene fluoride unit, the mixture is preferably dissolved in a good solvent described later, such as dimethylacetamide.

In addition, the said fluorine-containing block copolymer is a novel polymer, and is an amphiphilic block copolymer which consists of a hydrophilic part and a hydrophobic part. In general, when an amphiphilic block copolymer is dispersed in water, it becomes milky and forms an emulsion. At this time, it is widely known to form molecular aggregates called micelles.
In this specification, the micelle particularly represents a molecular aggregate comprising a fluorinated moiety and a non-fluorinated moiety. When the block copolymer containing a fluorine-based segment and a non-fluorine-based segment obtained by the above production method is dispersed in a fluorine-based solvent such as hexafluorobenzene or perfluorohexane, the emulsion becomes emulsion and the fluorine-based segment is outside. In addition, micelles with non-fluorine segments inside can be formed, and when dispersed in non-fluorine solvents such as chloroform, methylene chloride, tetrahydrofuran, hexane, methanol, water, etc., reverse micelles can be formed. Can do.
Examples of the method for producing micelles include a method in which a solvent is added to a sample, mixed and dispersed, and a method in which ultrasonic waves are applied to disperse the sample.
Although the mechanism of expression of the hydrophilic function of the fluorine-containing block copolymer is not clear, it is considered that such micelle formation may have some effect.

The polymer porous membrane of the present invention may be composed only of the fluoropolymer (A) having a vinylidene fluoride unit and the polymer (B), or the fluoropolymer (A), the polymer (B), And it may consist of other resin.

In the polymer porous membrane of the present invention, from the viewpoint of water permeability, the total of the fluoropolymer (A) and the polymer (B) is preferably 40% by mass or more, and 60% by mass or more of the entire polymer porous membrane. It is more preferable that it is 80 mass% or more.

As said other resin, a thermoplastic resin is mentioned, for example. A thermoplastic resin is a resin that deforms or flows by an external force when heated. Examples of the thermoplastic resin include polyethylene resin, polypropylene resin, acrylic resin, polyacrylonitrile, acrylonitrile-butadiene-styrene (ABS) resin, polystyrene resin, acrylonitrile-styrene (AS) resin, vinyl chloride resin, polyethylene terephthalate, Examples include polyamide resins, polyacetal resins, polycarbonate resins, modified polyphenylene ether resins, polyphenylene sulfide resins, polyamideimide resins, polyetherimide resins, polysulfone resins, polyethersulfone resins, and mixtures and copolymers thereof. Other resins miscible with these may be mixed.

The thermoplastic resin is preferably at least one selected from the group consisting of a polyethylene resin, a polypropylene resin, and an acrylic resin because of its high chemical resistance.

The polyethylene resin is a resin made of an ethylene homopolymer or an ethylene copolymer. The polyethylene resin may be composed of a plurality of types of ethylene copolymers. Examples of the ethylene copolymer include a copolymer of ethylene and one or more selected from linear unsaturated hydrocarbons such as propylene, butene and pentene.

The polypropylene resin is a resin made of a propylene homopolymer or a propylene copolymer. The polypropylene resin may be composed of a plurality of types of propylene copolymers. Examples of the propylene copolymer include a copolymer of propylene and one or more selected from linear unsaturated hydrocarbons such as ethylene, butene, and pentene.

The acrylic resin is a polymer compound mainly including polymers such as acrylic acid, methacrylic acid and derivatives thereof such as acrylamide and acrylonitrile (excluding the polymer (B)). Particularly preferred are acrylic ester resins and methacrylic ester resins.

When the polymer porous membrane of the present invention is composed of fluoropolymer (A), polymer (B) and the above-mentioned other resins, the membrane strength of the polymer porous membrane can be adjusted by adjusting the type and amount of the other resins. , Water permeability performance, blocking performance, etc. can be adjusted.

From the viewpoint of hydrophilization, the viewpoint of phase separation control, and the viewpoint of improving mechanical strength, the polymer porous membrane of the present invention is further made of polyvinylpyrrolidone, polyvinyl alcohol, polymethyl methacrylate resin, polyethylene oxide, montmorillonite, SiO. ₂ , additives such as CaCO ₃ and polytetrafluoroethylene may be included.

The porous polymer membrane of the present invention preferably has a pore size of 2 nm to 2.0 μm, more preferably 5 nm to 0.5 μm. If the pore diameter is too small, the gas or liquid permeability may be insufficient, and if the pore diameter is too large, the blocking performance may be lowered, or the mechanical strength may be lowered and the glass may be easily damaged.

The pore diameter is a magnification at which pores can be clearly confirmed, and the surface of the porous polymer membrane is photographed using SEM or the like, and the pore diameter is measured. In the case of an elliptical hole, the diameter of the pore can be obtained by (a × b) × 0.5, where a is the minor axis and b is the major axis. Further, a rough pore diameter can be obtained from the fine particle rejection rate. That is, for example, a porous film that blocks 90% or more of polystyrene fine particles of 50 nm or the like is considered to have a pore diameter of 50 nm or less.

For example, when the porous polymer membrane of the present invention has a performance of blocking 90% or more of fine particles of 50 nm, the pure water permeability coefficient is 1.0 × 10 ⁻⁹ m ³ / m ² / s / Pa or more. It is preferably 1.5 × 10 ⁻⁹ m ³ / m ² / s / Pa or more. The upper limit of the pure water permeability coefficient is not particularly limited, but it is desirable that the value is higher as long as the desired rejection and strength are maintained.

The pure water permeation coefficient can be determined by pressurizing ion-exchanged water at a temperature of 25 ° C. to 0.01 MPa or more as necessary with a pump or nitrogen pressure, and filtering the produced hollow fiber membrane or flat membrane. Specifically, it is obtained from the following formula.
Pure water permeability coefficient [m ³ / m ² / s / Pa] = (amount of permeated water) / (membrane area) / (permeation time) / (evaluation pressure)

In the polymer porous membrane of the present invention, the blocking rate of fine particles of 100 nm or 50 nm is preferably 90% or more, and more preferably 95% or more.

The fine particle blocking rate is obtained by the following equation after filtering a dispersion solution in which polystyrene latex fine particles having a controlled particle size are diluted to about 100 ppm with ion exchange water.
Fine particle rejection (%) = ((Evaluation stock solution absorbance) − (Transmission solution absorbance)) / (Evaluation stock solution absorbance) × 100

From the viewpoint of mechanical strength, the polymer porous membrane of the present invention preferably has a maximum point breaking strength of 0.5 MPa or more, more preferably 1.0 MPa or more. More preferably, it is 2.0 MPa or more.
The maximum point breaking strength can be obtained by measuring the breaking strength of a test piece under the conditions of a distance between chucks of 50 mm and a tensile speed of 200 mm / min, and a sectional area before the tensile test as a unit measurement area. Further, the breaking strength of the test piece is measured under the conditions of a distance between chucks of 25 mm and a tensile speed of 50 mm / min, and the cross-sectional area before the tensile test can be obtained as a unit measurement area. The direction of pulling the test piece is the extrusion direction in the case of a hollow fiber membrane, and the direction of casting in the case of a flat membrane.

From the viewpoint of toughness, the polymer porous membrane of the present invention preferably has a maximum point elongation of 70% or more, more preferably 100% or more.
The maximum point elongation is obtained from the elongation at the maximum point on the basis of the distance between the chucks of 50 mm and the tensile strength of 200 mm / min.
Further, the breaking strength of the test piece is measured under the conditions of a distance between chucks of 25 mm and a tensile speed of 50 mm / min, and it is also obtained from the elongation at the maximum point on the basis of the distance between chucks of 25 mm. The direction of pulling the test piece is the extrusion direction in the case of a hollow fiber membrane, and the direction of casting in the case of a flat membrane.

The structure of the polymer porous membrane of the present invention is not particularly limited. For example, a three-dimensional network structure in which the solid content spreads in a three-dimensional network, or a spherical structure in which a large number of spherical or nearly spherical solid components are connected directly or via a streaky solid content Etc. Moreover, you may have both these structures.

The shape of the polymer porous membrane of the present invention is preferably a flat membrane shape or a hollow fiber membrane shape.

In the case of a flat membrane shape, the polymer porous membrane of the present invention may be a composite membrane comprising a fluoropolymer layer comprising a fluoropolymer (A) and a polymer (B) and a porous substrate. In the case of the composite membrane, the surface of the porous substrate may be coated with a fluoropolymer layer composed of the fluoropolymer (A) and the polymer (B), or the porous substrate and the fluoropolymer (A) and The fluoropolymer layer which consists of a polymer (B) may be laminated | stacked.
A composite film comprising a porous substrate, a fluoropolymer layer comprising a fluoropolymer (A) and a polymer (B), and a resin layer comprising a resin other than the fluoropolymer (A) and the polymer (B); Also good. Examples of the resin forming the resin layer include the thermoplastic resins described above.

Examples of the porous substrate include polyester fibers, nylon fibers, polyurethane fibers, acrylic fibers, rayon fibers, woven fabrics, knitted fabrics, and nonwoven fabrics made of organic fibers such as cotton and silk. Moreover, the textile fabric, knitted fabric, or nonwoven fabric which consists of inorganic fibers, such as glass fiber and a metal fiber, is also mentioned. From the viewpoint of stretchability and cost, a porous substrate made of organic fibers is preferable.

The pore diameter of the surface of the porous substrate can be freely selected depending on the use, but is preferably 5 nm to 100 μm, more preferably 8 nm to 10 μm.

In the case of a flat membrane shape, the thickness of the polymer porous membrane is preferably 10 μm to 2 mm, and more preferably 30 μm to 500 μm. Even in the case of a composite membrane using the above porous substrate, the thickness of the polymer porous membrane is preferably within the above range.

The porous polymer membrane of the present invention is more preferably in the form of a hollow fiber membrane from the viewpoint of unit area and the amount of treated water per unit volume.

In the case of a hollow fiber membrane shape, the inner diameter of the hollow fiber membrane is preferably 100 μm to 10 mm, and more preferably 150 μm to 8 mm. The outer diameter of the hollow fiber membrane is preferably 120 μm to 15 mm, more preferably 200 μm to 12 mm.

In the case of a hollow fiber membrane shape, the thickness of the polymer porous membrane is preferably 20 μm to 3 mm, more preferably 50 μm to 2 mm. Moreover, although the hole diameter of the inner and outer surfaces of the hollow fiber membrane can be freely selected depending on the application, it is preferably in the range of 2 nm to 2.0 μm, more preferably 5 nm to 0.5 μm.

Next, the manufacturing method of the polymeric porous membrane of this invention is demonstrated.
The polymer porous membrane of the present invention is a step of mixing a fluoropolymer (A), a polymer (B), optionally a surfactant, a solvent, etc. to obtain a mixture, and molding the resulting mixture into a porous membrane shape It can manufacture by performing a process.

In the mixing step of the fluoropolymer (A) and the polymer (B), the fluoropolymer (A) and the polymer (B) are kneaded, or the polymer (B) is added to the aqueous dispersion of the fluoropolymer (A). Mixing, adding the fluoropolymer (A) to the aqueous dispersion of the polymer (B) and mixing, mixing the aqueous dispersion of the fluoropolymer (A) and the aqueous dispersion of the polymer (B) Although it can carry out, it is suitably carried out according to the method employ | adopted in the process of shape | molding the mixture obtained by this mixing process in porous membrane form.
In the case of mixing using an aqueous dispersion, it is possible to obtain a mixture of the fluoropolymer (A) and the polymer (B) by performing co-coagulation after mixing.
The blending ratio of the fluoropolymer (A) and the polymer (B) in the above mixture is the content ratio of the fluoropolymer (A) and the polymer (B) in the obtained polymer porous membrane of the present invention. It is set appropriately so as to be within the range.

In the mixing step, in addition to the fluoropolymer (A) and the polymer (B), other resins may be added and mixed.
As said other resin, other resins other than fluoropolymer (A) and polymer (B) which can be contained in the polymeric porous membrane of this invention demonstrated already are mentioned.

In the above production method, after the step of mixing the fluoropolymer (A), the polymer (B), optionally a surfactant, a hydrophilic polymer, a solvent and the like to obtain a mixture, the resulting mixture is formed into a porous film. A molding step is performed.

The step of forming on the porous membrane can be performed by various methods, for example, a phase separation method, a melt extraction method, a vapor coagulation method, a stretching method, an etching method, and a porous material by sintering a polymer sheet. A forming method such as a method for forming a porous film, a method for obtaining a porous film by crushing a polymer sheet containing bubbles, and a method using electrospinning can be used.

In the melt extraction method, inorganic fine particles and an organic liquid material are melt-kneaded into the mixture, extruded from a die at a temperature equal to or higher than the melting point of the fluoropolymer (A), or molded by a press or the like, and then solidified by cooling. Then, a porous structure is formed by extracting an organic liquid and inorganic fine particles.

In the vapor coagulation method, when the mixture is obtained, a good solvent is mixed in addition to the fluoropolymer (A) and the polymer (B), and the fluoropolymer (A) and the polymer (B) are dissolved in the good solvent. And a saturated vapor or mist of a non-solvent and / or a poor solvent that is compatible with the good solvent and does not dissolve the fluoropolymer (A) and the polymer (B) on at least one surface of the thin film-like material comprising the mixture. This is a method for forcibly supplying steam containing water.

The method for producing the porous membrane is preferably a phase separation method because the pore size can be easily controlled. Examples of the phase separation method include a thermally induced phase separation method (TIPS) and a non-solvent induced phase separation method (NIPS).

When using the thermally induced phase separation method, a step of obtaining a mixture by dissolving the fluoropolymer (A) and the polymer (B) in a solvent that is a poor solvent or a good solvent at a relatively high temperature, and cooling and solidifying the mixture A porous film-like molded product can be obtained by a production method comprising the steps of:

When the mixture in which the fluoropolymer (A) and the polymer (B) are dissolved in a solvent is maintained at a temperature higher than a temperature called cloud point (cloud point), it becomes a uniform one-phase liquid. In the following, phase separation occurs, and the fluoropolymer (A) and polymer (B) are separated into two phases, a concentrated phase and a solvent-rich phase, and when the temperature is lower than the crystallization temperature, the polymer matrix is fixed and a porous film is formed. .

When using a thermally induced phase separation method, it is preferable that the said mixture is 10-60 mass% with respect to the sum total with a fluoropolymer (A), a polymer (B), and a solvent. More preferably, it is 15-50 mass%.

By adjusting the concentration of the fluoropolymer (A) and the polymer (B) to an appropriate range, the viscosity of the mixture can be adjusted to an appropriate range. If the viscosity of the mixture is not within an appropriate range, the polymer porous membrane may not be formed.

The poor solvent cannot dissolve the fluoropolymer (A) and the polymer (B) at 5% by mass or more at a temperature lower than 60 ° C., but the melting point of the resin (the fluoropolymer (A) and the polymer (B ), Or in the case of containing other resins, the melting point is 5% by mass or more in the case where the melting point is the lowest of the melting points of the fluoropolymer (A), the polymer (B) and the other resin. It is a solvent that can be made to occur. A solvent that can dissolve 5% by mass or more of the fluoropolymer (A) and the polymer (B) at a temperature lower than 60 ° C. with respect to the poor solvent is referred to as a good solvent. A solvent that does not dissolve or swell the fluoropolymer (A) and the polymer (B) up to the melting point of the resin or the boiling point of the liquid is referred to as a non-solvent.

Examples of poor solvents include cyclohexanone, isophorone, γ-butyrolactone, methyl isoamyl ketone, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, aliphatic polyhydric alcohol, propylene glycol methyl ether, propylene carbonate, diacetone alcohol, glycerol triacetate, etc. Medium chain length alkyl ketones, esters, glycol esters and organic carbonates, and mixed solvents thereof. Fluorine-containing solvents such as HFC-365, diphenyl carbonate, methyl benzoate, diethylene glycol ethyl acetate, benzophenone and the like can also be mentioned. In addition, even if it is a mixed solvent of a non-solvent and a poor solvent, the solvent which satisfy | fills the definition of the said poor solvent is a poor solvent.
When the thermally induced phase separation method is used, a poor solvent is preferable as the solvent of the mixture. However, the solvent is not limited to this, and a good solvent may be used in consideration of the phase separation behavior of the fluoropolymer.

Good solvents include fluorine-containing solvents such as HCFC-225, lower alkyl such as N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethylacetamide, dimethylformamide, methyl ethyl ketone, acetone, methanol, tetrahydrofuran, tetramethylurea, and trimethyl phosphate. Examples thereof include ketones, esters, amides, and mixed solvents thereof.

Non-solvents include water, hexane, pentane, benzene, toluene, carbon tetrachloride, o-dichlorobenzene, trichloroethylene, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, butylene glycol, pentanediol, hexanediol. , Aliphatic hydrocarbons such as methanol, ethanol, propanol, and low molecular weight polyethylene glycol, aromatic hydrocarbons, aromatic polyhydric alcohols, chlorinated hydrocarbons, other chlorinated organic liquids, and mixed solvents thereof. .

When using a thermally induced phase separation method, it is preferable that the process of obtaining a mixture is what melt | dissolves a fluoropolymer (A) and a polymer (B) in the solvent which is a poor solvent or a good solvent at 30-270 degreeC. The melting temperature is preferably 40 to 250 ° C. When dissolved at a relatively high temperature, the total concentration of the fluoropolymer (A) and the polymer (B) can be increased, whereby a polymer porous membrane having high mechanical strength can be obtained. . If the above concentration is too high, the porosity of the resulting polymer porous membrane will be small, and the water permeation performance may be reduced. Moreover, if the viscosity of the prepared mixture is not in an appropriate range, there is a possibility that it cannot be formed into a porous membrane.

As a method for cooling and solidifying the mixture, for example, a method of discharging the mixture from a die into a cooling bath is preferable. When the polymer porous membrane is a flat membrane, a method of casting and immersing in a cooling bath can also be mentioned as a preferable method.

The cooling liquid that can be used as a cooling bath has a temperature lower than that of the mixture, and includes, for example, a solvent that is a poor solvent or a good solvent having a temperature of 0 to 80 ° C. and a concentration of 60 to 100% by mass. Liquid can be used. The cooling liquid may be a non-solvent or a non-solvent containing a poor solvent or a good solvent.

In the method for producing the porous membrane, the concentration of the mixture, the composition of the solvent for dissolving the fluoropolymer (A) and the polymer (B), and the composition of the cooling liquid constituting the cooling bath are important. By adjusting these compositions, the porous structure of the polymer porous membrane can be controlled.

For example, by changing the combination of the composition of the mixture and the composition of the cooling liquid on one side and the other side of the polymer porous membrane, the structure of one side of the polymer porous membrane and the structure of the other side are changed. It can be different.

When a non-solvent induced phase separation method is used as the step of forming the porous membrane, for example, a step of obtaining a mixture by dissolving the fluoropolymer (A) and the polymer (B) in a solvent, From the above, it is preferable to obtain a porous film-like molded product by a production method comprising a step of discharging into a coagulation bath containing a non-solvent.

By immersing the mixture in a coagulation bath containing a non-solvent, the concentration gradient of the solvent and the non-solvent in the mixture and the coagulation bath is used as a driving force to incorporate the non-solvent into the mixture and into the coagulation bath. Elution of the solvent occurs, and as a result, non-solvent induced phase separation can occur. According to this method, a dense skin layer is first formed on the outer surface where phase separation occurs due to substitution between a solvent and a non-solvent, and the phase separation phenomenon proceeds toward the inside of the film. As a result, it is also possible to manufacture an asymmetric membrane in which the pore diameter continuously increases toward the inside of the membrane following the skin layer.

When the non-solvent induced phase separation method is used, the mixture preferably comprises a fluoropolymer (A), a polymer (B), and a solvent. In addition to the fluoropolymer (A), the polymer (B) and the solvent, the mixture is preferably a non-solvent.

The mixture is based on the sum of fluoropolymer (A), polymer (B), solvent and non-solvent (if the mixture does not contain non-solvent, the sum of fluoropolymer (A), polymer (B), and solvent) The fluoropolymer (A) and the polymer (B) are preferably 5 to 60% by mass. More preferably, it is 10-50 mass%.
It is preferable that a non-solvent is 0.1-10 mass% with respect to the sum total of a fluoropolymer (A), a polymer (B), a solvent, and a nonsolvent. More preferably, it is 0.5-8 mass%.
By adjusting the concentration of the fluoropolymer (A) and the polymer (B) to an appropriate range, the viscosity of the mixture can be adjusted to an appropriate range. If the viscosity of the mixture is not within an appropriate range, the polymer porous membrane may not be formed.

The mixture may be at room temperature or heated. For example, 10-75 degreeC is preferable.

In the non-solvent induced phase separation method, the solvent exemplified in the thermally induced phase separation method can be used as the solvent. The solvent may be a poor solvent or a good solvent, but a good solvent is preferred. As the non-solvent, the non-solvent exemplified in the thermally induced phase separation method can be used.

The coagulation liquid that can be used as the coagulation bath is preferably solidified using a liquid containing a non-solvent, and may contain a poor solvent or a good solvent. As the non-solvent, the non-solvent exemplified in the thermally induced phase separation method can be used. For example, water can be preferably used.

In the step of forming the porous membrane, the thermally induced phase separation method and the non-solvent induced phase separation method may be used in combination.

In the non-solvent induced phase separation method and / or the thermally induced phase separation method, a porous film-shaped molded article is obtained by discharging a mixture of the fluoropolymer (A) and the polymer (B) in a solvent and then solidifying the mixture. Can be obtained. As the base, for example, a slit base, a double pipe base, a triple pipe base, or the like is used.

When a hollow fiber membrane-shaped molded product is produced as a porous membrane-shaped molded product, a double-tube type die or a triple-tube type die for spinning a hollow fiber membrane is preferably used as the die.

When using the above-mentioned double tube type die, discharge the mixture from the outer tube of the double tube type die, and solidify in a coagulation bath or cooling bath while discharging hollow part forming fluid such as ion exchange water from the inner tube. By doing so, a hollow fiber membrane can be obtained.

As the hollow portion forming fluid, gas or liquid can be usually used. In the thermally induced phase separation method, a liquid containing a poor solvent or a good solvent having a concentration of 60 to 100%, which is the same as the cooling liquid, can be preferably used, but a non-solvent or a non-solvent containing a poor solvent or a good solvent is used. It may be used. In the non-solvent induced phase separation method, the above-mentioned non-solvent is preferably used as the hollow portion forming fluid, and for example, water such as ion-exchanged water is preferable. Moreover, the non-solvent mentioned above may contain a poor solvent and a good solvent.

When the thermally induced phase separation method is used, the above-mentioned solvent is preferably used as the hollow portion forming fluid, and for example, a poor solvent such as glycerol triacetate is preferable. In addition, when a thermally induced phase separation method is used, nitrogen gas can also be used.

A hollow fiber membrane having two types of structures can also be formed by changing the composition of the hollow portion forming fluid and the cooling liquid or coagulating liquid. The hollow portion forming fluid may be supplied after cooling, but if the hollow fiber membrane is solidified only by the cooling power of the cooling bath, the hollow portion forming fluid may be supplied without cooling. .

The triple tube type die is suitable when two kinds of resin solutions are used. For example, a hollow fiber membrane can be obtained by discharging two types of mixture from an outer tube and an intermediate tube of a triple tube type die and solidifying in a coagulation bath or a cooling bath while discharging a hollow portion forming liquid from an inner tube. It can be. Also, the mixture is discharged from the outer tube of the triple tube type die, the resin solution made of resin other than the fluoropolymer (A) and the polymer (B) is discharged from the intermediate tube, and the hollow portion forming fluid is discharged from the inner tube. A hollow fiber membrane can be obtained by solidifying in a solidification bath or a cooling bath while discharging.
Examples of the resin other than the fluoropolymer (A) and the polymer (B) include those described above. Especially, the thermoplastic resin mentioned above is preferable and an acrylic resin is more preferable.

As described above, when a hollow fiber membrane is produced by a production method using a double tube type die or a triple tube type die, the amount of the solidification liquid or the cooling liquid may be made smaller than when a flat membrane is produced. It is preferable in that it can be performed.

When the shape of the polymer porous membrane to be produced is a hollow fiber membrane, on the outer surface or inner surface of the hollow fiber membrane obtained by the above method, a layer made of the fluoropolymer (A) or the fluoropolymer ( A resin layer made of a resin other than A) may be formed.

The fluoropolymer layer or resin layer can be formed by applying a solution or resin solution of the fluoropolymer (A) to the outer surface or inner surface of the hollow fiber membrane. As a method of applying the fluoropolymer (A) solution or resin solution to the outer surface of the hollow fiber membrane, the hollow fiber membrane is immersed in the fluoropolymer (A) solution or resin solution, or the hollow fiber membrane is coated with a fluoropolymer ( The method of dropping the solution or resin solution of A) is preferably used. As a method of applying the fluoropolymer (A) solution or resin solution to the inner surface of the hollow fiber membrane, a method of injecting the fluoropolymer (A) solution or resin solution into the hollow fiber membrane is preferably used.
As a method for controlling the coating amount of the solution or resin solution of the fluoropolymer (A), in addition to the method of controlling the coating amount itself of the solution or resin solution of the fluoropolymer (A), the porous film is made of a fluoropolymer (A ), Or after the fluoropolymer (A) solution or resin solution is applied to the porous membrane, a part of the fluoropolymer (A) solution or resin solution is scraped off, or an air knife is used. A method of using and blowing away and a method of adjusting the concentration during coating are also preferably used.

Moreover, when manufacturing a flat film-shaped molded object as a molded object of a porous membrane, it can manufacture by casting a mixture and immersing it in a cooling bath or a coagulation bath. Moreover, it can manufacture also by discharging a mixture to a cooling bath or a coagulation bath using a slit nozzle | cap | die.

When the polymer porous membrane of the present invention is a composite membrane composed of a porous substrate, the present invention includes a method of immersing the porous substrate in a mixture, a method of applying the mixture to at least one surface of the porous substrate, and the like. It is also possible to obtain a polymer porous membrane.

A polymer porous membrane having excellent water permeability can be obtained by the production method described above, but if the water permeability is not sufficient, the porous membrane obtained by the production method may be further stretched. .

In the step of forming the porous membrane, as a method for controlling the pore size, for example, an additive for controlling the pore size is added to the mixture to form a porous structure by the fluoropolymer (A) and the polymer (B). During or after forming the porous structure, the pore diameter of the polymer porous membrane can be controlled by eluting the additive. Further, the additive may remain in the porous membrane.

In both the non-solvent induced phase separation method and the thermally induced phase separation method, the mixture may contain an additive. After forming the porous structure, the pore diameter of the polymer porous membrane can be controlled by eluting the additive. The additive may remain in the porous membrane as necessary.

Examples of additives include organic compounds and inorganic compounds. As an organic compound, it is preferable that it is what is melt | dissolved in the solvent which comprises a mixture, or what is disperse | distributed uniformly. Furthermore, a non-solvent contained in the coagulating liquid in the non-solvent induced phase separation method and a solvent dissolved in the solvent contained in the cooling liquid in the thermally induced phase separation method are preferable.

For example, as organic compounds, water-soluble polymers such as polyvinylpyrrolidone, polyethylene glycol, polyvinyl alcohol, polyethyleneimine, polyacrylic acid, and textlan, surfactants such as Tween 40 (polyoxyethylene sorbitan monopalmitate), glycerin, and saccharides Etc.

As the inorganic compound, a water-soluble compound is preferably used. For example, calcium chloride, lithium chloride, barium sulfate and the like can be mentioned.

It is also possible to control the average pore diameter of the surface by controlling the phase separation speed by the type, concentration and temperature of the non-solvent in the coagulating liquid without using an additive. In general, when the phase separation rate is high, the average pore size on the surface is small, and when the phase separation rate is low, the average pore size is large. Moreover, adding a non-solvent to the mixture is also effective for controlling the phase separation rate.

From the viewpoint of hydrophilization, phase separation control, and mechanical strength improvement, the mixture further includes polyvinylpyrrolidone, polyvinyl alcohol, polymethyl methacrylate resin, montmorillonite, SiO ₂ , TiO ₂ , CaCO ₃ , polytetra An additive such as fluoroethylene may be contained.

Moreover, in the said manufacturing method, after obtaining the porous film-shaped molded object, the wet process may be performed to the said porous film-shaped molded object.
The wet treatment may be performed, for example, by immersing the porous membrane-shaped molded product in an alcohol such as methanol or ethanol, and then substituting it with water.
Furthermore, the polymer porous membrane obtained by the above production method may be treated with an alkali from the viewpoint of improving water permeability. Examples of the alkali include NaOH aqueous solution, KOH aqueous solution, aqueous ammonia, and amine solution. These may contain alcohols such as ethanol and methanol, and organic solvents. In particular, the alkali preferably contains an alcohol, but is not limited thereto.

The porous membrane-like molded product obtained by the above production method is suitable as a microfiltration membrane or an ultrafiltration membrane used for water treatment such as drinking water production, water purification treatment, and wastewater treatment. Since the porous membrane-like molded product obtained by the above production method has high permeability and excellent chemical resistance, it is suitable for a polymer porous membrane for water treatment.

In addition, the porous membrane-like molded product obtained by the above production method is also suitably used in the medical field, food field, battery field and the like.

In the medical field, as a membrane for blood purification for the purpose of removing blood waste products by extracorporeal circulation such as blood dialysis, blood filtration, blood filtration dialysis, etc. The obtained porous membrane-like molded product can be used.

In the food field, a porous membrane-shaped product obtained by the above production method can be used for the purpose of separating and removing yeasts used for fermentation and concentrating liquids.

In the battery field, a porous membrane obtained by the above production method as a separator for a battery or a polymer solid electrolyte base material for allowing an electrolyte to permeate but not a product produced by a battery reaction. Shaped moldings can be used.

EXAMPLES Hereinafter, although an Example is hung up and demonstrated in more detail about this invention, this invention is not limited only to these Examples.

(Weight average molecular weight)
The weight average molecular weight was determined by gel permeation chromatography (GPC).

[Composition of fluoropolymer by NMR (nuclear magnetic resonance)]
For the 1H-NMR (nuclear magnetic resonance method) measurement, JNM-EX270 (manufactured by JEOL: 270 MHz) was used. Deuterated chloroform was used as the solvent.

[Pure water permeability coefficient]
The pure water permeability coefficient was determined by pressurizing ion-exchanged water with nitrogen at a pressure of 0.01 MPa or higher at a temperature of 25 ° C., and filtering with the produced hollow fiber membrane or flat membrane.
Pure water permeability coefficient [m ³ / m ² / s / Pa] = (amount of permeated water) / (membrane area) / (permeation time) / (evaluation pressure)

[Particle rejection rate]
The fine particle rejection was obtained by filtering a dispersion solution in which polystyrene latex fine particles (100 nm) having a controlled particle size were diluted to about 100 ppm with ion-exchanged water as an evaluation stock solution, and obtained by the following formula.
Fine particle blocking ratio [%] = ((Evaluation stock solution absorbance) − (Transmission solution absorbance)) / (Evaluation stock solution absorbance) × 100

[Maximum breaking strength]
The maximum breaking strength was determined by measuring the breaking strength of the test piece under the conditions of a distance between chucks of 50 mm and a tensile speed of 200 mm / min, and the cross-sectional area before the tensile test as a unit measurement area.

[Maximum elongation]
The maximum point elongation was obtained by measuring the breaking strength of the test piece under the conditions of a distance between chucks of 50 mm and a tensile speed of 200 mm / min, and calculating from the elongation at the maximum point based on the distance between chucks of 50 mm.

(Synthesis Example 1)
A 300 ml four-necked eggplant flask is charged with 100 g of methyl ethyl ketone (MEK) and 58 mmol (25 g) of CH ₂ ═C (CH ₃ ) —COOC ₂ H ₄ C ₆ F ₁₃ (hereinafter abbreviated as “13-SFMA”). Nitrogen was bubbled through for 20 minutes. Thereafter, AIBN was charged into a 0.60 mmol (0.1 g) reaction solution, and the temperature of the water bath was increased so that the internal temperature was 60 ° C. The three-one motor was rotated at 250 rpm. The reaction was traced by gas chromatography and NMR, and when 13-SFMA monomer was consumed, CH ₂ ═C (CH ₃ ) —COO (CH ₂ CH ₂ O) _m CH ₃ (hereinafter abbreviated as “PEG-MA”). 58 mmol (27.5 g) (M: 475, m = 9) was added, and when all the monomers were consumed, the reaction was terminated and the mixture was allowed to cool. The reaction solution was concentrated with an evaporator, reprecipitated with hexane, the polymer was recovered, and the target polymer (C6-PEG) was obtained by vacuum drying.
The chemical shift value (δ ppm) of ¹ H-NMR in deuterated chloroform solvent is 0.8-1.5 (br, —CH ₂ C (COO —) (CH ₃ ) —), 1.5 ( _{br, -CH 2 C (COO -} ) (CH 3) -), 2.6 (br, -C (= O) OCH 2 CH 2 C 6 F 13), 3.5 (br, -OCH 2 CH 2 O -), it was _{4.2 (br, -C (= O} ) OCH 2 CH 2 C 6 F 13, -OCH 2 CH 2 OCH 3).

(Synthesis Example 2)
In a 100 ml four-necked eggplant flask, 35 g of ethyl acetate, 90 mmol (9 g) of methyl methacrylate and 12 mmol (6 g) of PEG-MA were put, and nitrogen was blown into the solution for 20 minutes for bubbling. Thereafter, AIBN was charged into a 0.3 mmol (0.05 g) reaction solution and reacted at 60 ° C. for 4 hours. The reaction solution was reprecipitated with a hexane / methanol mixed solvent and water to recover the polymer, and then the target polymer (MMA-PEG) was obtained by vacuum drying.

(Production Example 1) Synthesis Example of PVdF (Polyvinylidene Fluoride) SUS autoclave having an internal volume of 2 liters was charged with 910 g of ion-exchanged water and 0.5 g of methylcellulose, and after substituting with nitrogen, the inside of the tank was evacuated and then ethyl acetate was added. 1.5 g of 1,1-difluoroethylene (VdF) (vinylidene fluoride) 365 g was charged and kept constant at 28 ° C. After the temperature in the tank was constant, 12 g of dinormalpropyl peroxydicarbonate was charged to start suspension polymerization. After 10 hours, the inside of the tank was depressurized to complete the reaction. The polymer slurry was dehydrated and washed with water, and then dried at 105 ° C. for 24 hours to obtain a polyvinylidene fluoride powder. The obtained polyvinylidene fluoride powder was 110 g and had a weight average molecular weight of 270,000.

(Production Example 2) Synthesis Example of VdF / TFE Copolymer 1300 g of ion-exchanged water was charged into a 4 liter glass-lined autoclave and the inside of the tank was evacuated after nitrogen substitution, and then 1300 g of octafluorocyclobutane was charged. The inside of the tank was heated to 45 ° C. and stirred at a stirring speed of 580 rpm. After the temperature in the tank was constant, 150 g of a mixed gas of tetrafluoroethylene (TFE) / 1,1-difluoroethylene (VdF) = 6/94 mol% and 10 g of ethyl acetate were charged, and then 50 mass of dinormalpropyl peroxydicarbonate. 2 g of a methanol solution was charged and suspension polymerization was started. From the start of the reaction, a mixed gas of TFE / VdF = 20/80 mol% was continuously supplied to keep the pressure in the tank at 1.3 MPa. The stirring speed was kept at 580 rpm.
After 24 hours from the start of the reaction, the inside of the tank was depressurized to complete the reaction. The reaction product was washed with water and dried at 120 ° C. for 12 hours to obtain a powder of a VdF / TFE copolymer. The obtained powder polymer was 600 g, the weight average molecular weight was 230,000, and the composition ratio was VdF / TFE = 80/20 (mol%).

Example 1
A blend of the polyvinylidene fluoride obtained in Production Example 1 and the polymer (C6-PEG) obtained in Synthesis Example 1 at a weight ratio of 6: 1 is 14.0% by mass, and dimethylacetamide is 86.0% by mass. The polymer solution was prepared as follows.
This polymer solution was applied to a glass plate with an applicator (203 μm) and immediately immersed in a water coagulation bath at 25 ° C. for 10 minutes to obtain a flat porous film. The pure water permeability coefficient of the obtained porous membrane was 8.72 × 10 ⁻⁹ (m ³ / m ² / s / Pa). The fine particle rejection was 91%.

(Comparative Example 1)
A flat porous membrane was obtained in the same manner as in Example 1 except that PEG400 (manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of C6-PEG. The pure water permeability coefficient of the obtained porous membrane was 2.68 × 10 ⁻⁹ (m ³ / m ² / s / Pa). The fine particle rejection was 93%.

(Comparative Example 2)
A flat porous membrane was obtained in the same manner as in Example 1 except that PEG600 (manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of C6-PEG. The pure water permeability coefficient of the obtained porous membrane was 3.07 × 10 ⁻⁹ (m ³ / m ² / s / Pa). The fine particle rejection was 92%.

(Comparative Example 3)
The polymer solution was adjusted so that the polyvinylidene fluoride obtained in Production Example 1 was 12.0% by mass and dimethylacetamide was 88.0% by mass.
This polymer solution was applied to a glass plate with an applicator (203 μm) and immediately immersed in a water coagulation bath at 25 ° C. for 10 minutes to obtain a flat porous film. The pure water permeability coefficient of the obtained porous membrane was 1.84 × 10 ⁻⁹ (m ³ / m ² / s / Pa). The fine particle rejection was 95%.

(Example 2)
A blend of the VdF / TFE copolymer obtained in Production Example 2 and the polymer (C6-PEG) obtained in Synthesis Example 1 at a weight ratio of 6: 1 was 14.0% by mass, and dimethylacetamide was 86.0% by mass. The polymer solution was adjusted to be%.
This polymer solution was applied to a glass plate with an applicator (203 μm) and immediately immersed in a water coagulation bath at 25 ° C. for 10 minutes to obtain a flat porous film. The obtained porous membrane had a pure water permeability coefficient of 1.20 × 10 ⁻⁸ (m ³ / m ² / s / Pa). The fine particle rejection was 90%.

(Comparative Example 4)
A flat porous membrane was obtained in the same manner as in Example 2 except that PEG400 was used instead of C6-PEG. The pure water permeability coefficient of the obtained porous membrane was 2.11 × 10 ⁻⁹ (m ³ / m ² / s / Pa). The fine particle rejection was 94%.

(Comparative Example 5)
A flat porous membrane was obtained in the same manner as in Example 2 except that PEG600 was used instead of C6-PEG. The pure water permeability coefficient of the obtained porous membrane was 1.06 × 10 ⁻⁸ (m ³ / m ² / s / Pa). The fine particle rejection was 81%.

(Comparative Example 6)
The polymer solution was adjusted so that the VdF / TFE copolymer obtained in Production Example 2 was 12.0% by mass and dimethylacetamide was 88.0% by mass.
This polymer solution was applied to a glass plate with an applicator (203 μm) and immediately immersed in a water coagulation bath at 25 ° C. for 10 minutes to obtain a flat porous film. The pure water permeability coefficient of the obtained porous membrane was 6.78 × 10 ⁻⁹ (m ³ / m ² / s / Pa). The fine particle rejection was 88%.

(Example 3)
Each component was mixed at 25 ° C., and 2.6% by mass of the polymer (C6-PEG) obtained in Synthesis Example 1, 15.4% by mass of polyvinylidene fluoride obtained in Production Example 1, and 82% by mass of dimethylacetamide. Got. This polymer solution was discharged from a double-tube type cap while accompanying ion exchange water as an internal liquid, and solidified in ion exchange water to obtain a hollow fiber membrane. The obtained hollow fiber membrane had an outer diameter of 1.03 mm and an inner diameter of 0.89 mm. The obtained hollow fiber membrane had a pure water permeability coefficient of 6.57 × 10 ⁻⁹ (m ³ / m ² / s / Pa). The fine particle rejection was 91%. The maximum point breaking strength was 1.5 MPa, and the maximum point elongation was 90%.

(Comparative Example 7)
Each component was mixed at 25 ° C. to obtain a polymer solution of 18.0% by mass of the VdF / TFE copolymer obtained in Production Example 2 and 82.0% by mass of dimethylacetamide. This polymer solution was discharged from a double-tube type cap while accompanying ion exchange water as an internal liquid, and solidified in ion exchange water to obtain a hollow fiber membrane. The obtained hollow fiber membrane had an outer diameter of 0.92 mm and an inner diameter of 0.84 mm. Although a water pressure of 0.1 MPaG was applied at 25 ° C., pure water did not permeate. The maximum point breaking strength was 8.0 MPa, and the maximum point elongation was 740%.

(Comparative Example 8)
Each component was mixed at 25 ° C. to obtain a polymer solution of 18.0% by mass of polyvinylidene fluoride obtained in Production Example 1 and 82.0% by mass of dimethylacetamide. This polymer solution was discharged from a double-tube type cap while accompanying ion exchange water as an internal liquid, and solidified in ion exchange water to obtain a hollow fiber membrane. The obtained hollow fiber membrane had an outer diameter of 0.81 mm and an inner diameter of 0.74 mm. Although a water pressure of 0.1 MPaG was applied at 25 ° C., pure water did not permeate. The maximum point breaking strength was 11.0 MPa, and the maximum point elongation was 440%.

(Comparative Example 9)
Each component was mixed at 25 ° C., and a polymer solution of 18.0% by mass of VdF / TFE copolymer obtained in Production Example 2, 3.0% by mass of polyethylene oxide (PEG 600), and 79.0% by mass of dimethylacetamide was obtained. Obtained. This polymer solution was discharged from a double-tube type cap while accompanying ion exchange water as an internal liquid, and solidified in ion exchange water to obtain a hollow fiber membrane. The obtained hollow fiber membrane had an outer diameter of 0.91 mm and an inner diameter of 0.80 mm. Although a water pressure of 0.1 MPaG was applied at 25 ° C., pure water did not permeate. The maximum point breaking strength was 4.7 MPa, and the maximum point elongation was 590%.

(Comparative Example 10)
The blend of polyvinylidene fluoride obtained in Production Example 1 and MMA-PEG obtained in Synthesis Example 2 at a weight ratio of 3: 1 is 18.0% by mass, and dimethylacetamide is 82.0% by mass. A polymer solution was prepared. This polymer solution was applied to a glass plate with an applicator (203 μm) and immediately immersed in a water coagulation bath at 25 ° C. for 10 minutes to obtain a flat porous film. The pure water permeability coefficient of the obtained porous membrane was 9.21 × 10 ⁻⁹ (m ³ / m ² / s / Pa). The maximum point breaking strength was 1.2 MPa, and the maximum point elongation was 30%. Moreover, although the polymer solution used for this flat film preparation was transparent, the refractive index nonuniformity was observed visually and it was confirmed that it was inferior in compatibility.

Claims (8)

Fluoropolymer (A) having a vinylidene fluoride unit and the following general formula (1):

(In the formula, R represents a hydrogen atom or a methyl group. Rf represents a fluorinated alkyl group having 1 to 25 carbon atoms.) The polymer unit derived from the monomer (a) represented by: General formula (2):

(In the formula, R represents a hydrogen atom or a methyl group. R ₁ represents an alkylene group having 1 to 10 carbon atoms. R ₂ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a carbon number. 1 represents a group in which at least one hydrogen atom of the alkyl group is substituted with a hydroxyl group, m represents an integer of 0 to 200. However, when m = 0, R ₂ represents a hydrogen atom or carbon. And a polymer (B) having a polymer unit derived from the monomer (b) represented by the formula (1), wherein one or more hydrogen atoms of the alkyl group are substituted with a hydroxyl group. Polymer porous membrane. Fluoropolymer (A) having a vinylidene fluoride unit and the following general formula (1):

(In the formula, R represents a hydrogen atom or a methyl group. Rf represents a fluorinated alkyl group having 1 to 10 carbon atoms.) The polymer unit derived from the monomer (a) represented by: General formula (2):

(In the formula, R represents a hydrogen atom or a methyl group. R ₁ represents an alkylene group having 1 to 10 carbon atoms. R ₂ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. And a polymer (B) having a polymer unit derived from the monomer (b) represented by the formula (1): The polymer porous membrane according to claim 1 or 2, wherein the polymer (B) is 0.01 to 40% by mass relative to the fluoropolymer (A). The polymer (B) is a block polymer comprising a segment composed of polymerized units derived from the monomer (a) and a segment composed of polymerized units derived from the monomer (b). The polymeric porous membrane as described. The polymer (B) has a weight average molecular weight of 1,000 to 2,000,000. The polymer porous membrane according to any one of claims 1 to 4. It is a hollow fiber membrane, The polymeric porous membrane in any one of Claims 1-5. The porous polymer membrane according to any one of claims 1 to 5, which is a flat membrane. The polymer porous membrane according to any one of claims 1 to 5, which is used for water treatment.