JP2012161741A - Microporous crystalline polymer membrane, production method therefor, and filtration filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a microporous crystalline polymer membrane that has excellent water resistance and ion adsorption capacity, is highly hydrophilic, has a long filtration life, and has an excellent permeation flow rate; a production method for the microporous crystalline polymer membrane capable of producing the microporous crystalline polymer membrane efficiently; and a filtration filter using the microporous crystalline polymer membrane.SOLUTION: In the microporous crystalline polymer membrane with an asymmetric pore structure, at least a portion of an exposed surface of the microporous crystalline polymer membrane is covered with a radical polymer obtained by polymerizing a composition comprising a radical-polymerizable monomer, a functional compound comprising at least one of an ion-exchanging group or a chelating group has undergone an addition reaction with at least a portion of the radical polymer, and the radical-polymerizable monomer is at least one selected from acrylate, methacrylate, acrylamide and derivatives thereof.

Description

  The present invention uses a crystalline polymer microporous membrane having high filtration efficiency used for microfiltration of gas, liquid, etc., a method for producing a crystalline polymer microporous membrane, and the crystalline polymer microporous membrane. The present invention relates to a filter for filtration.

Microporous membranes have been known for a long time and are widely used in filtration filters and the like. Examples of such a microporous membrane include those manufactured using cellulose ester as a raw material (see Patent Document 1 etc.), those manufactured using aliphatic polyamide as a raw material (see Patent Document 2 etc.), and polyfluorocarbon as a raw material. And the like (see Patent Document 3 etc.) and those made of polypropylene (see Patent Document 4 etc.).
These microporous membranes are used for filtration and sterilization of electronic industry cleaning water, semiconductor manufacturing chemicals, pharmaceutical water, pharmaceutical manufacturing process water, food water, etc. A highly reliable microporous membrane is attracting attention from the viewpoint of particle trapping. Among these, a microporous film made of a crystalline polymer has excellent chemical resistance, and in particular, a microporous film made from polytetrafluoroethylene (PTFE) has excellent heat resistance and chemical resistance. The demand growth is remarkable.

In general, the filterable amount per unit area of the microporous membrane is small (that is, the filtration life is short). For this reason, when industrially used, in order to increase the membrane area, it is necessary to use many filtration units in parallel, and from the viewpoint of cost reduction of the filtration process, the filtration life is increased. Is needed. For example, as an effective microporous membrane for reducing the flow rate due to clogging or the like, an asymmetric pore membrane has been proposed in which the average pore diameter gradually decreases from the inlet side toward the outlet side.
For example, a microporous membrane of crystalline polymer in which the average pore size on the surface of the membrane is larger than the average pore size on the back surface and the average pore size continuously changes from the front surface to the back surface has been proposed (Patent Document 5). reference). According to this proposal, by performing filtration with the surface (surface) having a large average pore diameter as the inlet side, fine particles can be efficiently captured, and the filtration life can be improved.

Further, as a hydrophilic treatment method for a crystalline polymer microporous membrane having asymmetric pores, for example, in Patent Document 6, the exposed surface of the crystalline polymer microporous membrane having an asymmetric pore structure is treated with hydrogen peroxide or a water-soluble solvent. It has been proposed to perform a hydrophilic treatment by impregnation with an aqueous solution of the above, laser irradiation, chemical etching and the like.
However, a crystalline polymer microporous membrane having asymmetric pores has a heated surface, a non-heated surface, and the inside thereof, and the degree of crystallinity of the crystalline polymer at each site is different. In the crystallization method, the entire membrane cannot be uniformly hydrophilized, and if an attempt is made to perform the hydrophilization treatment, it is necessary to perform the hydrophilization treatment several times for each condition depending on the degree of crystallinity. It ’s bad. Further, the hydrophilicity of the produced hydrophilic treatment film was not sufficiently satisfactory. Furthermore, in the method of performing hydrophilic treatment by irradiating with an ultraviolet laser and an ArF laser, there is a problem that the film is damaged by the irradiation with the ultraviolet laser and the ArF laser, and the film strength is deteriorated.

In addition, as a hydrophilization treatment method for the crystalline polymer microporous membrane, a cationic polymerizable monomer and a cationic polymerization initiator are included, and the cationic polymerizable monomer is polymerized to form at least a part of the surface of the porous membrane. A modification method has been proposed, and optionally a functional monomer containing a quaternary ammonium salt or the like has been proposed (see Patent Document 7).
However, this proposal has a problem that the filtration flow rate and the filtration life of the porous membrane cannot be improved to a sufficiently satisfactory level.

Also, in recent years, in the manufacture of semiconductors, in order to obtain ultra-pure water, etc., which can be used for ultra-high purity, a filter capable of simultaneously capturing fine metal ions at a concentration of less than ppm at the same time as capturing fine particles has appeared. It is desired. There is a particular need for a microfiltration filter that has a metal ion scavenging ability and has a high resistance to chemicals such as acids, alkalis, and oxidants and has few eluates. In the past, attempts have been made to give the microporous membrane itself an ion exchange function or an ion adsorption function for such purposes.
As a crystalline polymer microporous film imparted with an ion adsorption function, for example, in Patent Document 8, an arbitrary functional group that is reactive with an activated polar group from the film and has an affinity for a specific ion A porous membrane provided with the above ligand has been proposed.
However, in this proposal, a porous membrane having a symmetric pore structure is used, and when such a porous membrane is functionalized, the filtration flow rate is not significantly improved, and the filtration life is not improved. There's a problem.

US Pat. No. 1,421,341 US Pat. No. 2,783,894 US Pat. No. 4,196,070 West German Patent No. 3,003,400 JP 2007-332342 A JP 2009-119212 A JP 2007-503862 A Japanese National Publication No. 9-511948

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, the present invention is a crystalline polymer microporous membrane having excellent water resistance and ion adsorption capacity, high hydrophilicity, long filtration life, and excellent permeation flow rate, and the crystalline polymer microporous membrane. It is an object of the present invention to provide a method for producing a crystalline polymer microporous membrane that can be well produced, and a filter for filtration using the crystalline polymer microporous membrane.

Means for solving the problems are as follows. That is,
<1> A crystalline polymer microporous membrane having an asymmetric pore structure,
At least a part of the exposed surface of the crystalline polymeric microporous membrane is coated with a radical polymer obtained by polymerizing a composition containing a radical polymerizable monomer, and at least a part of the radical polymer has an ion exchange group. And a functional compound containing at least one of a chelate group, and the radical polymerizable monomer is at least one selected from acrylate, methacrylate, acrylamide, acrylic acid and derivatives thereof A crystalline polymer microporous membrane.
<2> The crystalline polymer microporosity according to <1>, wherein the radical polymerizable monomer has at least one of a carboxyl group, an amino group, a hydroxyl group, an epoxy group, an acrylamide group, an isocyanate group, and an acid chloride group. It is a membrane.
<3> The crystalline polymer microporous membrane according to any one of <1> to <2>, wherein the functional compound is a compound having a reactive group with a radical polymer.
<4> The average hole diameter in the first surface of the two exposed surfaces is larger than the average hole diameter in the second surface located on the opposite side of the first surface, and the first surface from the first surface The crystalline polymer microporous membrane according to any one of <1> to <3>, which has a plurality of pores whose average pore diameter continuously changes toward the surface of No. 2.
<5> A film obtained by heating one surface of a film containing a crystalline polymer constituting a crystalline polymer microporous film and stretching a semi-baked film imparted with a temperature gradient in the thickness direction of the film <4> is a crystalline polymer microporous film.
<6> The crystalline polymer microporous film according to <4> to <5>, wherein the second surface is a heating surface.
<7> Ratio of the average pore diameter d _{3 on} the first surface of the crystalline polymer microporous membrane and the average pore diameter d _{4 on} the second surface before coating the exposed surface with the radical polymerizable monomer polymer ( d ₃ / d ₄ ),
The ratio of the average pore diameter on the first surface of the crystalline polymer microporous membrane after coating the exposed surface with the fluorosurfactant d ₃ ′ to the average pore diameter d ₄ ′ on the second surface (d ₃ '/ _{d 4')} and although the following _{formula, (d 3 '/ d 4} ') / (d 3 / d 4)> 1, the satisfying <1 from> according to any one of <6> crystalline Polymer microporous membrane.
<8> The crystalline polymer is polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene / hexafluoropropylene copolymer, tetrafluoroethylene / ethylene copolymer, polyfluoride. Vinylidene fluoride, polychlorotrifluoroethylene, chlorotrifluoroethylene-ethylene copolymer, polyethylene, polypropylene, nylon, polyacetal, polybutylene terephthalate, polyethylene terephthalate, syndiotactic polystyrene, polyphenylene sulfide, polyether ether ketone, wholly aromatic <1> to <7> above, which is at least one selected from aromatic polyamide, wholly aromatic polyester, and polyether nitrile A crystalline polymer microporous membrane described in any of the above.
<9> The crystalline polymer microporous membrane according to any one of <1> to <7>, wherein the crystalline polymer is polytetrafluoroethylene.
<10> a hydrophilic treatment step of applying a composition containing a radical polymerizable monomer to the exposed surface of the crystalline polymer microporous film having an asymmetric pore structure, and polymerizing the radical polymerizable monomer;
An addition reaction treatment step in which a functional compound containing at least one of an ion exchange group and a chelate group is added to a part of the radical polymer, and the radical polymerizable monomer is an acrylate, methacrylate, acrylamide, acrylic It is a method for producing a crystalline polymer microporous membrane, characterized in that it is at least one selected from acids and derivatives thereof.
<11> An asymmetric heating step of heating one surface of a film made of a crystalline polymer to form a semi-baked film having a temperature gradient in the thickness direction of the film;
A stretching step of stretching the semi-baked film to form a crystalline polymer microporous film having an asymmetric pore structure;
The method for producing a crystalline polymer microporous membrane according to <10>, further comprising:
<12> The <10> to <11>, wherein the radical polymerizable monomer includes at least one of a carboxyl group, an amino group, a hydroxyl group, an epoxy group, an acrylamide group, an isocyanate group, and an acid chloride group. The method for producing a crystalline polymer microporous membrane according to any one of the above.
<13> The method for producing a crystalline polymer microporous membrane according to any one of <10> to <12>, wherein the functional compound is a compound having a reactive group with a radical polymer. .
<14> A filtration filter comprising the crystalline polymer microporous membrane according to any one of <1> to <9>.

  According to the present invention, the above-described problems can be achieved by solving the above-mentioned problems, water resistance, ion adsorption ability, high hydrophilicity, long filtration life, and excellent permeation flow rate. Polymeric microporous membrane, crystalline polymer microporous membrane production method capable of efficiently producing the crystalline polymer microporous membrane, and filtration filter using the crystalline polymer microporous membrane Can be provided.

FIG. 1 is a diagram illustrating a structure of a general pleated filter element before being assembled in a housing. FIG. 2 is a view showing the structure of a general filter element before being assembled into the housing of the capsule filter cartridge. FIG. 3 is a view showing the structure of a general capsule filter cartridge integrated with a housing. 4A is a diagram schematically showing a cut surface of a crystalline polymer microporous membrane having a symmetrical hole before functionalization treatment (before hydrophilization treatment and addition reaction treatment) in Comparative Example 2. FIG. FIG. 4B is a diagram schematically showing a cut surface of a crystalline polymer microporous membrane having a symmetrical hole after functionalization treatment (after hydrophilization treatment and addition reaction treatment) in Comparative Example 2. 5A is a diagram schematically showing a cut surface of a crystalline polymer microporous membrane having asymmetric pores before functionalization treatment (after hydrophilization treatment and addition reaction treatment) in Example 1. FIG. 5B is a diagram schematically showing a cut surface of a crystalline polymer microporous membrane having asymmetric pores after functionalization treatment (after hydrophilization treatment and addition reaction treatment) in Example 1. FIG.

(Crystalline polymer microporous membrane and crystalline polymer microporous membrane production method)
The crystalline polymer microporous membrane of the present invention is a crystalline polymer microporous membrane having an asymmetric pore structure, wherein at least a part of the exposed surface of the crystalline polymer microporous membrane contains a radical polymerizable monomer. A functional polymer containing at least one of an ion exchange group and a chelate group is subjected to an addition reaction with at least a part of the radical polymer.
The method for producing a crystalline polymer microporous membrane of the present invention includes a hydrophilization treatment step and an addition reaction treatment step, and includes an asymmetric heating step, a stretching step, a crystalline polymer film production step, and, if necessary, other methods. Comprising the steps.
Hereinafter, the crystalline polymer microporous membrane and the method for producing the crystalline polymer microporous membrane of the present invention will be described in detail.

The crystalline polymer microporous membrane of the present invention is a crystalline polymer microporous membrane having an asymmetric pore structure, and a composition containing a radical polymerizable monomer as will be described later. The product is coated with a radical polymer obtained by polymerizing the product, and a functional compound containing at least one of an ion exchange group and a chelate group is added to at least a part of the radical polymer.
Further, the crystalline polymer microporous membrane is preferably obtained by heating one surface of a film made of a crystalline polymer and stretching a semi-fired film having a temperature gradient in the thickness direction of the film. .
In this case, of the two exposed surfaces of the crystalline polymer microporous membrane obtained by stretching, the surface having the larger average pore diameter is defined as the first surface, and is located on the opposite side of the first surface. When the surface is the second surface, the second surface is preferably a heating surface.
The hole is a continuous hole (both ends are open) from the first surface to the second surface.
In the following description, the first surface having the larger average pore diameter is referred to as “non-heated surface”, and the second surface having the smaller average pore diameter is referred to as “heating surface”. This is merely a name given for convenience in order to make the description of the present invention easier to understand. Therefore, any surface of the unsintered crystalline polymer film may be heated to become a “heating surface” after semi-sintering.

-Crystalline polymer-
The “crystalline polymer” is not particularly limited as long as it is a polymer in which a crystalline region in which long chain molecules are regularly arranged in a molecular structure and an amorphous region that is not regularly arranged are mixed. Can be appropriately selected according to the purpose. Such polymers exhibit crystallinity by physical treatment. For example, when a polyethylene film is stretched by an external force, a phenomenon in which a transparent film becomes cloudy at first is recognized. This is because the crystallinity is expressed by aligning the molecular arrangement in the polymer in one direction by an external force.

There is no restriction | limiting in particular as said crystalline polymer, According to the objective, it can select suitably, For example, polyalkylene, polyester, polyamide, polyether, a liquid crystalline polymer etc. are mentioned. Specifically, polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene / hexafluoropropylene copolymer, tetrafluoroethylene / ethylene copolymer, polyvinylidene fluoride, Polychlorotrifluoroethylene, chlorotrifluoroethylene / ethylene copolymer, polyethylene, polypropylene, nylon, polyacetal, polybutylene terephthalate, polyethylene terephthalate, syndiotactic polystyrene, polyphenylene sulfide, polyether ether ketone, wholly aromatic polyamide, Examples include wholly aromatic polyesters, fluororesins, and polyether nitriles. These may be used individually by 1 type and may use 2 or more types together.
Among these, from the viewpoint of chemical resistance and handleability, polyalkylene (for example, polyethylene and polypropylene) is preferable, and fluorine-based polyalkylene in which the hydrogen atoms of the alkylene group in the polyalkylene are partially or entirely substituted with fluorine atoms. Is more preferable, and polytetrafluoroethylene (PTFE) is particularly preferable.
The density of the polyethylene varies depending on the degree of branching, the degree of branching is high, and the degree of crystallization is low density polyethylene (LDPE), the degree of branching is low and the degree of crystallization is high density polyethylene (HDPE). Any of these can be used. Among these, HDPE is particularly preferable from the viewpoint of crystallinity control.

  The crystalline polymer preferably has a glass transition temperature of 40 ° C to 400 ° C, more preferably 50 ° C to 350 ° C. The mass average molecular weight of the crystalline polymer is preferably 1,000 to 100,000,000. The number average molecular weight of the crystalline polymer is preferably 500 to 50,000,000, more preferably 1,000 to 10,000,000.

In the crystalline polymer microporous membrane of the present invention, the average pore diameter in the first surface is larger than the average pore diameter in the second surface, and the average pore diameter from the first surface toward the second surface is It has a plurality of continuously changing holes, that is, the average hole diameter of the non-heated surface (first surface) is larger than the average hole diameter of the heated surface (second surface).
The crystalline polymer microporous membrane has a thickness of “10”, an average pore diameter in the thickness portion “1” in the depth direction from the surface is P1, and an average pore diameter in the thickness portion of “9” is P2. P1 / P2 is preferably 2 to 10,000, and more preferably 3 to 100.
The crystalline polymer microporous membrane preferably has a ratio of the average pore diameter between the non-heated surface and the heated surface (non-heated surface / heated surface ratio) of 5 to 30 times, more preferably 10 to 25 times. 15 to 20 times is particularly preferable.
There is no restriction | limiting in particular as an average hole diameter of the hole in the non-heating surface (1st surface) of the said crystalline polymer microporous film | membrane, Although it can select suitably according to the objective, 0.1 micrometer-500 micrometers are Preferably, 0.25 μm to 250 μm is more preferable, and 0.50 μm to 100 μm is particularly preferable.
If the average pore diameter is less than 0.1 μm, the flow rate may decrease, and if it exceeds 500 μm, fine particles may not be efficiently captured. On the other hand, when it is within the particularly preferable range, it is advantageous in terms of flow rate and fine particle capturing ability.
There is no restriction | limiting in particular as an average hole diameter of the hole part in the heating surface (2nd surface) of the said crystalline polymer microporous film | membrane, Although it can select suitably according to the objective, 0.01 micrometer-5.0 micrometers Is preferable, 0.025 μm to 2.5 μm is more preferable, and 0.05 μm to 1.0 μm is particularly preferable.
If the average pore diameter is less than 0.01 μm, the flow rate may decrease, and if it exceeds 5.0 μm, fine particles may not be efficiently captured. On the other hand, when it is within the particularly preferable range, it is advantageous in terms of flow rate and fine particle capturing ability.

  Here, the average pore diameter is, for example, a film surface photograph (SEM photograph, magnification of 1,000 to 5,5) with a scanning electron microscope (Hitachi S-4000 type, vapor deposition is Hitachi E1030 type, both manufactured by Hitachi, Ltd.). 000 times) and the obtained photograph is transferred to an image processing apparatus (main body name: Nippon Avionics Co., Ltd., TV image processor TVIP-4100II, control software name: Ratok System Engineering Co., Ltd., TV image processor image command 4198). The average pore diameter can be obtained by obtaining an image consisting only of crystalline polymer fibers, measuring a predetermined number of pore diameters in the image, and calculating the image.

  In addition to the above characteristics, the crystalline polymer microporous membrane of the present invention has an average pore diameter that continuously changes from the non-heated surface (first surface) to the heated surface (second surface). In addition to the above-described features (first embodiment), both of the embodiments (second embodiment) having a single-layer structure are included. By further adding these additional features, the filter life can be effectively improved.

  In the first aspect, “the average pore diameter continuously changes from the non-heated surface to the heated surface” means that the horizontal axis indicates the distance t in the thickness direction from the non-heated surface (the depth from the surface). This means that the graph is drawn with one continuous line when the average pore diameter D is taken on the vertical axis. The graph from the non-heated surface (t = 0) to the heated surface (t = film thickness) may consist of only a region with a negative slope (dD / dt <0), or a negative slope. A region and a region with a zero slope (dD / dt = 0) may be mixed, or a region with a negative slope and a positive region (dD / dt> 0) may be mixed. . Preferably, the region is composed only of a negative slope region (dD / dt <0), or a negative slope region and a zero slope region (dD / dt = 0) are mixed. More preferably, it is composed of only a negative slope region (dD / dt <0).

  It is preferable that at least the non-heated surface of the film is included in the region where the inclination is negative. In the region where the slope is negative (dD / dt <0), the slope may be always constant or different. For example, if the crystalline polymer microporous membrane of the present invention consists only of a negative slope region (dD / dt <0), the dD on the heated surface of the membrane is higher than the dD / dt on the non-heated surface of the membrane. A mode in which / dt is large can be taken. Further, it is possible to adopt a mode in which dD / dt gradually increases (a mode in which the absolute value decreases) from the non-heated surface to the heated surface of the crystalline polymer microporous film.

  The “single layer structure” referred to in the second embodiment excludes a multilayer structure formed by bonding or laminating two or more layers. That is, the “single layer structure” in the second aspect means a structure having no boundary between layers existing in a multilayer structure. In the second aspect, it is preferable that a surface having an average pore size smaller than the average pore size of the non-heated surface and larger than the average pore size of the heated surface is present in the film.

  The crystalline polymer microporous membrane of the present invention preferably has both the features of the first embodiment and the features of the second embodiment. That is, the average pore diameter of the non-heated surface of the crystalline polymer microporous membrane is larger than the average pore diameter of the heated surface, the average pore diameter continuously changes from the non-heated surface to the heated surface, and a single layer What is a structure is preferable. With such a crystalline polymer microporous membrane, fine particles can be captured more efficiently when filtration is performed from the non-heated surface side, the filtration life can be greatly improved, and it is easy and inexpensive. Can also be manufactured.

  The film thickness of the crystalline polymer microporous film is preferably 1 μm to 300 μm, more preferably 5 μm to 100 μm, and particularly preferably 10 μm to 80 μm.

In the present invention, at least a part of the exposed surface of the crystalline polymer microporous membrane is coated with a radical polymer obtained by polymerizing a composition containing a radical polymerizable monomer (hydrophilization treatment), and the radical polymer A functional compound containing at least one of an ion exchange group and a chelate group is added to at least a part of (addition reaction treatment).
Here, in addition to the exposed surfaces (first surface and second surface) of the crystalline polymer microporous film, the exposed surface includes the periphery of the hole and the inside of the hole.

  The composition containing the radical polymerizable monomer comprises at least one radical polymerizable monomer selected from acrylate, methacrylate, acrylamide, acrylic acid and derivatives thereof, and, if necessary, other radical polymerization. Other components such as a polymerizable monomer, a solvent, a radical polymerization initiator, a photosensitizer, and an antioxidant.

<Radically polymerizable monomer>
The radical polymerizable monomer is not particularly limited as long as it is at least one selected from acrylate, methacrylate, acrylamide, acrylic acid and derivatives thereof, and can be appropriately selected according to the purpose. Alkyl (meth) acrylates such as hydroxy-2-propyl acrylate, 2-hydroxy-1-propyl acrylate, hydroxypropyl methacrylate, 2,3-dihydroxypropyl acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxyethyl methacrylate; 4- Glycidyl (meth) acrylates such as hydroxybutyl acrylate glycidyl ether and glycidyl acrylate; aminoethyl methacrylate, dimethylaminoethyl methacrylate Primary amine (meth) acrylates such as diethylaminoethyl methacrylate; urethane (meth) acrylates; acrylamides such as acrylamide, methacrylamide, ethacrylamide, and N, N-dimethylacrylamide; acrylic acids such as acrylic acid and methacrylic acid; Examples include (meth) acrylic acid chlorides such as acrylic acid chloride and methacrylic acid chloride. These may be used individually by 1 type and may use 2 or more types together.
Among these, glycidyl (meth) acrylates and acrylic acids are preferable in that the reactivity with the reactive compound is good.

The radical polymerizable monomer preferably contains at least one of a carboxyl group, an amino group, a hydroxyl group, an epoxy group, an acrylamide group, an isocyanate group, and an acid chloride group.
Examples of the radical polymerizable monomer containing a carboxyl group include acrylic acid, methacrylic acid, and carboxyethyl acrylate. Examples of the radical polymerizable monomer containing an amino group include dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate. Examples of the radical polymerizable monomer containing a hydroxyl group include 4-hydroxybutyl acrylate and hydroxyethyl methacrylate. Examples of the radical polymerizable monomer containing an epoxy group include 4-hydroxybutyl acrylate glycidyl ether and glycidyl acrylate. Examples of the radically polymerizable monomer containing an acrylamide group include acrylamide and N, N-dimethylacrylamide. Examples of the radical polymerizable monomer containing an isocyanate group include urethane (meth) acrylates. Examples of the radical polymerizable monomer containing an acid chloride group include acrylic acid chloride.
There is no restriction | limiting in particular as said urethane (meth) acrylates, According to the objective, it can select suitably, A commercial item can be used. Examples of the commercially available products include Desmodur HL (Bayer AG, manufactured by Leverkusen), Roskydal UA VP LS 2265 (Bayer AG, manufactured by Leverkusen), and the like.

There is no restriction | limiting in particular as content in the said composition of the said radically polymerizable monomer, Although it can select suitably according to the objective, 0.1 mass%-30 mass% are preferable, 0.2 mass%- 25 mass% is more preferable, and 0.3 mass%-20 mass% is especially preferable.
If the content is less than 0.1% by mass, the entire microporous membrane of the crystalline polymer may not be hydrophilized. If the content exceeds 30% by mass, the crystalline polymer micropores There is a risk that the permeate flow rate may be reduced by closing the pores of the conductive membrane.

<< Radical polymerization initiator >>
As the radical polymerization initiator, both a photo radical polymerization initiator and a thermal radical polymerization initiator can be suitably used.

-Photo radical polymerization initiator-
The photo radical polymerization initiator is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the Irgacure series (for example, Irgacure 651, commercially available from Ciba Specialty Chemicals) IRGACURE 754, IRGACURE 184, IRGACURE 2959, IRGACURE 907, IRGACURE 369, IRGACURE 379, IRGACURE 819, etc.), DAROCURE series (eg DAROCURE TPO, DAROCURE 1173 etc.), Quantacure PD Ezacure series (for example, Ezacure TZM, Ezacure TZT, etc.) commercially available from the company may be mentioned.

-Thermal radical polymerization initiator-
The thermal radical polymerization initiator is not particularly limited and may be appropriately selected depending on the intended purpose. For example, α, α′-azobisisobutyronitrile, SI series commercially available from Sanshin Chemical Co., Ltd. (For example, SI-100 etc.) etc. are mentioned.

Although there is no restriction | limiting in particular as addition amount of the said radical polymerization initiator, 0.1 mass part-20 mass parts are preferable with respect to 100 mass parts of said radical polymerizable monomers, 0.5 mass part-15 mass parts Is more preferable, and 1.0 to 10 parts by mass is particularly preferable.
When the addition amount is less than 0.1 parts by mass, the polymerization reaction may be slow, and when it exceeds 20 parts by mass, the film strength may be brittle.

<< solvent >>
The solvent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include water; alcohols such as methanol, ethanol, isopropanol and ethylene glycol; ketones such as acetone and methyl ethyl ketone (MEK); , Ethers such as dioxane and propylene glycol monomethyl ether acetate; dimethylformamide, dimethyl sulfoxide and the like.

<< Photosensitizer >>
A photosensitizer can be used in combination with the composition as necessary. By using the photosensitizer, the reactivity is improved, and the mechanical strength and adhesive strength of the cured product can be improved.
The photosensitizer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, and photoreduction. Specific examples include benzoin derivatives such as benzoin methyl ether, benzoin isopropyl ether, α, α-dimethoxy-α-phenylacetophenone; benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate Benzophenone derivatives such as 4,4′-bis (diethylamino) benzophenone; thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone; anthraquinone derivatives such as 2-chloroanthraquinone and 2-methylanthraquinone; Examples include acridone derivatives such as lidon and N-butylacridone; α, α-diethoxyacetophenone, benzyl, fluorenone, xanthone, and uranyl compounds. These may be used individually by 1 type and may use 2 or more types together.
Examples of commercially available photosensitizers include Anthracure (registered trademark) UVS-1331 (manufactured by Kawasaki Kasei Kogyo Co., Ltd.), Kayacure DETX-S (manufactured by Nippon Kayaku Co., Ltd.), and the like.

<< Antioxidant >>
The said composition can contain other additives, such as antioxidant, unless the effect of this invention is impaired.
Examples of commercially available antioxidants include dibutylhydroxytoluene (BHT), Irganox 1010, Irganox 1035FF, Irganox 565, and the like.

In the crystalline polymer microporous membrane of the present invention, at least a part of the exposed surface of the crystalline polymer microporous membrane is coated with a radical polymer obtained by polymerizing a composition containing a radical polymerizable monomer. The membrane before coating and the membrane after coating are each made fine, and the crystalline polymer microporous membrane is extracted with a solvent such as methanol, water, DMF, etc., and the components of the extract are NMR, IR, etc. It can be confirmed by measuring and analyzing using
In addition, when the crystalline polymer microporous membrane cannot be extracted into a solvent, the membrane is finely chopped and covered with KBr, and measurement and analysis are performed by IR, and supercritical methanol is used. The components can be confirmed by measuring and analyzing the components with MASS, NMR, IR, etc. while decomposing the polymer.

  In addition, the functional compound described later is added to the radical polymer, and the measurement and analysis are performed by IR while finely chopping the whole film and covered with KBr, and using supercritical methanol, While decomposing the polymer, its components can be confirmed by measurement and analysis by MASS, NMR, IR, and the like.

In the crystalline polymer microporous membrane of the present invention, at least a part of the exposed surface of the crystalline polymer microporous membrane is coated with a radical polymer obtained by polymerizing a composition containing a radical polymerizable monomer. Therefore, in addition to the exposed surfaces (first surface and second surface) of the crystalline polymer microporous membrane, the periphery of the hole portion and the inside of the hole portion are uniformly coated, and thus hydrophilic. , High filtration life and excellent permeate flow rate.
On the other hand, if at least a part of the exposed surface of the crystalline polymer microporous membrane is coated with a prepolymerized radical polymer, the exposed surface is covered, particularly around the pores and inside the pores. May not be uniform, so that sufficient hydrophilicity cannot be obtained, and the filtration life and permeate flow rate cannot be improved as compared with the crystalline polymer microporous membrane of the present invention.
The distribution and degree of the coating of the radical polymer can be identified by, for example, examining the element distribution on the exposed surface by elemental analysis by energy dispersive X-ray scanning electron microscope spectroscopy (EDX-SEM). .

In the crystalline polymer microporous membrane of the present invention, at least a part of the exposed surface of the crystalline polymer microporous membrane is coated with a radical polymer obtained by polymerizing a composition containing a radical polymerizable monomer. Therefore, hydrophilicity can be imparted, and a remarkable asymmetric structure can be formed in the asymmetric membrane, thereby further improving the filtration life. This is because the radical polymer is thicker than the coarse filtration portion on the first surface (non-heating surface) side as it goes to the dense portion on the second surface (heating surface) side of the crystalline polymer microporous membrane. This is considered to be because a remarkable asymmetric structure can be formed in which the degree of continuous change in the average particle diameter from the first surface to the second surface can be increased.
This is also clear from satisfying the relationship shown below.
As shown in FIG. 5A, the crystalline polymer micro-layer before coating the radical polymer obtained by polymerizing the composition containing the radical polymerizable monomer on the exposed surface of the crystalline polymer microporous membrane (before hydrophilization treatment). The ratio (d ₃ / d ₄ ) between the average pore diameter d _{3 on} the first surface of the porous membrane and the average pore diameter d _{4 on} the second surface;
As shown in FIG. 5B, the exposed surface of the crystalline polymer microporous membrane is coated with a radical polymer obtained by polymerizing the composition containing the radical polymerizable monomer (after hydrophilization treatment), and then the crystalline polymer microparticles are coated. The ratio (d ₃ ′ / d ₄ ′) between the average pore diameter d ₃ ′ on the first surface of the porous membrane and the average pore diameter d ₄ ′ on the second surface is expressed by the following equation: (d ₃ ′ / d ₄ ′) / (d ₃ / d ₄ )> 1 is preferably satisfied, (d ₃ ′ / d ₄ ′) / (d ₃ / d ₄ )> 1.005 is more preferable, and (d ₃ ′ / D ₄ ′) / (d ₃ / d ₄ )> 1.01 is particularly preferable. When (d ₃ ′ / d ₄ ′) / (d ₃ / d ₄ ) is 1 or less, the lifetime may be extremely shortened due to particle clogging or the like.

The coverage of the radical polymer is not particularly limited as long as at least a part of the exposed surface of the crystalline polymer microporous membrane is coated, and depends on the surface area of the crystalline polymer microporous membrane and the like. For example, it can be appropriately adjusted based on the porosity described in JP-A-8-283447. That is, the surface area has a correlation with the porosity of the crystalline polymer microporous membrane, and the coverage of the radical polymer can be optimized in relation to the porosity. It can be calculated using the following formula (1) and the following formula (2).
There is no restriction | limiting in particular as said porosity, Although it can select suitably according to the objective, 60% or more is preferable and 60%-95% are more preferable. When the porosity is less than 60%, the hydrophilicity becomes low, and a desired permeation flow rate may not be obtained in the crystalline polymer microporous membrane. When the porosity exceeds 95%, the crystalline polymer The strength of the microporous membrane may decrease.
The lower the porosity of the crystalline polymer microporous membrane, the lower the coverage of the radical polymer, and conversely, the higher the porosity, the higher the coverage, but the range is the following formula (1) and It should just be in the range prescribed | regulated by following formula (2).
When the coverage is less than the range defined by the following formula (1) and the following formula (2), a crystalline polymer microporous membrane having high hydrophilicity and a long filtration life may not be obtained. If it is larger than the above range, clogging may occur.
(C / 5) -11.5 ≦ D ≦ (C / 5) −9.5 Formula (1)
D = (application mass of radical polymerizable monomer / crystalline polymer microporous film mass) × 100 Formula (2)
(In the formula (1), “C” represents the porosity (%) of the crystalline polymer microporous membrane.)

<Functional compounds>
The functional compound is not particularly limited as long as it contains at least one of an ion exchange group and a chelate group, and can be appropriately selected according to the purpose. A reactive group with a radical polymer, and further if necessary And other components.

-Ion exchange group-
The ion exchange group is a functional group that captures metal ions and the like by ionic bonds.
The ion exchange group is not particularly limited as long as it is a functional group that ionically bonds with a metal ion or the like, and can be appropriately selected according to the purpose. For example, a sulfonic acid group, a phosphoric acid group, a carboxyl group, etc. Anion exchange groups such as cation exchange groups, primary amino groups, secondary amino groups, tertiary amino groups, quaternary amino groups, and quaternary ammonium bases can be mentioned.

-Chelate group-
The chelate group is a functional group that captures a metal ion or the like by a chelate (coordination) bond.
The chelate group is not particularly limited as long as it is a functional group capable of chelate (coordination) bonding with a metal ion, and can be appropriately selected according to the purpose. For example, nitrilotriacetic acid derivative (NTA) group, iminodiacetic acid Group, iminodiethanol group, aminopolycarboxylic acid, aminopolyphosphonic acid, porphyrin skeleton, phthalocyanine skeleton, cyclic ether, cyclic amine, phenol and lysine derivatives, phenanthrolin group, terpyridine group, bipyridine group, triethylenetetraamine group, Multidentate ligands such as diethylenetriamine group, tris (carboxymethyl) ethylenediamine group, diethylenetriaminepentaacetic acid group, polypyrazolylboric acid group, 1,4,7-triazocyclononane group, dimethylglyoxime group, diphenylglyoxime group Etc. .

-Reactive group with radical polymer-
There is no restriction | limiting in particular as a reactive group with the said radical polymer, According to the objective, it can select suitably, For example, an amino group, a hydroxyl group, an epoxy group, or these derivative groups etc. are mentioned. Among these, an amino group and a hydroxyl group are preferable.
Specific examples of the functional compound having a reactive group include an amino group as a reactive group, pentaethylenehexamine, aminoethanesulfonic acid, phosphorylethanolamine, etc .; a hydroxyethylenediamine group having a reactive group as a hydroxyl group. Acetic acid, choline, hydroxypropanesulfonic acid, disodium glycerophosphate pentahydrate and the like; and others include cyclic compounds such as ethylene sulfide and oxetane compounds.

-Membrane fixation of functional compounds-
The functional compound is present in the side chain of the radical polymer because the radical wall surface of the crystalline polymer microporous membrane (film made of a crystalline polymer) is coated with a radical polymerizable monomer and fixed by polymerization. By addition reaction to the reactive group, it is fixed to the crystalline polymer microporous membrane in a non-covalent bond state.
In addition, the fact that the functional compound is fixed to the crystalline polymer microporous membrane can be confirmed by, for example, a back titration method described in JP-A-2005-131482.

A flow rate can be increased by fixing the functional compound to a membrane.
The flow rate is generally determined by the hole diameter (D), the pressure loss (ΔP), the number of holes (n), the film thickness (L), and the liquid viscosity (η) as shown in the following formula. By fixing the functional compound to the membrane, it was expected that the pore diameter would decrease and the flow rate would decrease, but in reality, a higher flow rate could be achieved. This is presumed to be because hydrophilicity has been improved.

(Method for producing crystalline polymer microporous membrane)
The method for producing a crystalline polymer microporous membrane according to the present invention includes at least a hydrophilization treatment step and an addition reaction treatment step, and includes a crystalline polymer film preparation step, an asymmetric heating step, a stretching step, and, if necessary, other processes. Comprising the steps.
The hydrophilic treatment and the addition reaction treatment are collectively referred to as functionalization treatment.

<Crystalline polymer film production process>
There is no restriction | limiting in particular as a kind of crystalline polymer raw material used when manufacturing the unbaking crystalline film which consists of crystalline polymers, The crystalline polymer mentioned above can be used preferably. Among these, polyethylene or a crystalline polymer in which a hydrogen atom is substituted with a fluorine atom is preferable, and for example, polytetrafluoroethylene (PTFE) is more preferable. As the polytetrafluoroethylene, polytetrafluoroethylene produced by an emulsion polymerization method can be usually used, preferably a fine powder obtained by coagulating an aqueous dispersion obtained by emulsion polymerization. Polytetrafluoroethylene can be used.
As a number average molecular weight of the crystalline polymer used as a raw material, 500-50,000,000 are preferable and 1,000-10,000,000 are more preferable.
The number average molecular weight of polytetrafluoroethylene used as a raw material is preferably 2.5 million to 10 million, more preferably 3 million to 8 million.
There is no restriction | limiting in particular as said polytetrafluoroethylene raw material, You may select and use the polytetrafluoroethylene raw material currently marketed suitably. For example, “Polyflon Fine Powder F104U” manufactured by Daikin Industries, Ltd. is preferable.

  It is preferable to prepare a film by preparing a mixture obtained by mixing the polytetrafluoroethylene raw material with an extrusion aid, and extruding and rolling the mixture. As the extrusion aid, a liquid lubricant is preferably used, and specific examples thereof include solvent naphtha and white oil. As the extrusion aid, a hydrocarbon oil such as “Isopar” manufactured by Esso Oil Co., Ltd. sold in the market can be used. The addition amount of the extrusion aid is preferably 20 to 30 parts by mass with respect to 100 parts by mass of the crystalline polymer.

Paste extrusion is usually preferably performed at 50 ° C to 80 ° C. There is no restriction | limiting in particular about extrusion shape, Although it can select suitably according to the objective, Usually, it is preferable to make it rod-shaped. The extrudate is then rolled into a film. Rolling can be performed, for example, by calendaring with a calendar roll at a speed of 50 m / min. The rolling temperature can usually be set to 50 ° C to 70 ° C. Then, it is preferable to remove the extrusion aid by heating the film to obtain a crystalline polymer unfired film. Although the heating temperature at this time can be suitably determined according to the kind of crystalline polymer to be used, it is preferably 40 ° C to 400 ° C, more preferably 60 ° C to 350 ° C. For example, when polytetrafluoroethylene is used, 150 ° C. to 280 ° C. is preferable, and 200 ° C. to 255 ° C. is more preferable. The heating can be performed by a method such as passing the film through a hot air drying furnace. The thickness of the unsintered crystalline polymer film thus produced can be appropriately adjusted according to the thickness of the crystalline polymer microporous film to be finally produced, and is stretched in a later step. In such a case, it is preferable to adjust the thickness in consideration of stretching.
In the production of an unsintered crystalline polymer film, the items described in “Polyfluorocarbon Handbook” (published by Daikin Industries, Ltd., revised in 1983) can be appropriately employed.

<Asymmetric heating process>
The asymmetric heating step is a step of heating one surface of a film made of a crystalline polymer to form a semi-baked film in which a temperature gradient is formed in the thickness direction of the film.
Here, the semi-firing means that the crystalline polymer is heat-treated at a temperature not lower than the melting point of the fired body and not higher than the melting point of the unfired body + 15 ° C.
In the present invention, an unsintered body of a crystalline polymer means one that has not been subjected to a heat treatment for firing. The melting point of the crystalline polymer means the temperature of the endothermic curve peak that appears when the unsintered crystalline polymer is measured with a differential scanning calorimeter. The melting point of the fired body and the melting point of the unfired body vary depending on the kind of crystalline polymer, the average molecular weight, and the like, but are preferably 50 ° C to 450 ° C, more preferably 80 ° C to 400 ° C.
Such a temperature can be considered as follows. For example, when the crystalline polymer is polytetrafluoroethylene, the sintered body has a melting point of about 324 ° C. and the green body has a melting point of about 345 ° C. Therefore, in the case of a polytetrafluoroethylene film, the temperature is preferably 327 ° C. to 360 ° C., more preferably 335 ° C. to 350 ° C., for example, heating to a temperature of 345 ° C. The semi-fired body is in a state where a melting point of about 324 ° C. and a melting point of about 345 ° C. are mixed.

The semi-baking is performed by heating one surface (heating surface) of a film made of a crystalline polymer. Thereby, the heating temperature can be controlled asymmetrically in the thickness direction, and the crystalline polymer microporous membrane of the present invention can be easily produced.
Further, as the temperature gradient in the thickness direction of the film made of the crystalline polymer, the temperature difference between the non-heated surface and the heated surface is preferably 30 ° C. or more, and more preferably 50 ° C. or more.

As the heating method, various methods such as a method of blowing hot air, a method of contacting with a heating medium, a method of contacting with a heated material, a method of irradiating infrared rays, and heating by electromagnetic waves such as microwaves can be used.
Although it does not restrict | limit especially as said heating method, The method of making a heating thing contact the surface of a film, and infrared irradiation are especially preferable. It is particularly preferable to select a heating roll as the heated product. If it is a heating roll, the semi-firing can be carried out continuously in a flow operation industrially, and temperature control and maintenance of the apparatus are easy. The temperature of the heating roll can be set to the temperature at which the semi-fired body is formed. The time for which the film is brought into contact with the heating roll is the time necessary for the target half-baking to sufficiently proceed, preferably 30 seconds to 120 seconds, more preferably 45 seconds to 90 seconds, and 60 seconds to 80 seconds. Is more preferable.

There is no restriction | limiting in particular as said infrared irradiation, According to the objective, it can select suitably.
The general definition of the infrared can be referred to “practical infrared” (Human and History, published in 1992). In the present invention, the infrared ray means an electromagnetic wave having a wavelength of 0.74 μm to 1,000 μm, of which a wavelength range of 0.74 μm to 3 μm is a near infrared ray, and a wavelength range of 3 μm to 1,000 μm is far away. Infrared.

In the present invention, since it is preferable that there is a temperature difference between the non-heated surface and the heated surface of the semi-baked film, far infrared rays advantageous for heating the surface layer are preferably used.
The type of infrared device is not particularly limited as long as it can irradiate infrared rays having a target wavelength, and can be appropriately selected according to the purpose. In general, near infrared rays are bulbs (halogen lamps), far infrared rays are A heating element such as ceramic, quartz, or metal oxide surface can be used.
Moreover, if it is infrared irradiation, a semi-baking can be performed continuously by a flow operation industrially, and also temperature control and apparatus maintenance are easy. Moreover, since it is non-contact, it does not cause defects such as cleanness and fluff.
The film surface temperature by the infrared irradiation can be controlled by the output of the infrared irradiation apparatus, the distance between the infrared irradiation apparatus and the film surface, the irradiation time (conveying speed), and the ambient temperature, and is set to the temperature at which the above-mentioned semi-baked body is formed However, it is preferably 327 ° C to 380 ° C, more preferably 335 ° C to 360 ° C. When the surface temperature is less than 327 ° C., the crystal state does not change, and the pore diameter may not be controlled. When the surface temperature exceeds 380 ° C., the entire film melts, and the shape is excessively deformed. Thermal decomposition may occur.
The irradiation time of the infrared rays is not particularly limited, and is a time necessary for the desired half-baking to sufficiently proceed, preferably 30 seconds to 120 seconds, more preferably 45 seconds to 90 seconds, and more preferably 60 seconds to 80 seconds is more preferable.

The heating in the asymmetric heating step may be performed continuously, or may be performed intermittently by dividing into several times.
When the heating surface of the film is continuously heated, it is preferable to cool the non-heating surface simultaneously with the heating of the heating surface in order to maintain a temperature gradient between the heating surface and the non-heating surface of the film.
The method for cooling the non-heated surface is not particularly limited and may be appropriately selected depending on the purpose. For example, a method of blowing cold air, a method of contacting with a refrigerant, a method of contacting with a cooled material, or by cooling. Various methods such as cooling can be used, and it is preferably performed by bringing a cooling material into contact with the non-heated surface of the film. As the cooling object, it is particularly preferable to select a cooling roll as the cooling object. If it is a cooling roll, like the heating of a heating surface, it can carry out an industrial semi-baking continuously by a flow operation | work, and also temperature control and apparatus maintenance are easy. The temperature of the cooling roll can be set so as to cause a difference from the temperature at which the semi-fired body is formed. The time for which the film is brought into contact with the cooling roll is a time required for the intended half-baking to sufficiently proceed, and is usually 30 seconds to 120 seconds, assuming that the film is simultaneously performed with the heating step. The time is preferably 45 seconds to 90 seconds, more preferably 60 seconds to 80 seconds.
The surface material of the heating roll and cooling roll can be stainless steel, which is generally excellent in durability, and particularly SUS316. In the production method of the present invention, the non-heated surface of the film is preferably brought into contact with the heating and cooling roll, but a roller set at a temperature lower than that of the heating and cooling roll may be brought into contact with the heating surface of the film. Absent. For example, a roller maintained at room temperature may be pressed from the film heating surface to fit the film to the heating roll. Moreover, you may make the heating surface of a film contact a guide roll before or after making it contact with a heating roll.
Moreover, also when performing the said asymmetrical heating process intermittently, it is preferable to suppress the temperature rise of a non-heating surface by heating the heating surface of a film intermittently and cooling a non-heating surface.

<Extension process>
The stretching step is a step of stretching the semi-baked film.
The stretching is preferably performed in both the longitudinal direction and the width direction of the semi-baked film. At this time, the longitudinal direction and the width direction may be sequentially stretched or biaxially stretched at the same time.
When sequentially stretching in the longitudinal direction and the width direction, respectively, it is preferable to first stretch in the longitudinal direction and then stretch in the width direction.
The stretching ratio in the longitudinal direction is preferably 4 to 100 times, more preferably 8 to 90 times, and still more preferably 10 to 80 times. The stretching temperature in the longitudinal direction is preferably 100 ° C to 300 ° C, more preferably 200 ° C to 290 ° C, and particularly preferably 250 ° C to 280 ° C.
The stretching ratio in the width direction is preferably 10 to 100 times, more preferably 12 to 90 times, still more preferably 15 to 70 times, and particularly preferably 20 to 40 times. The stretching temperature in the width direction is preferably 100 ° C to 300 ° C, more preferably 200 ° C to 290 ° C, and particularly preferably 250 ° C to 280 ° C.
The area stretch ratio is preferably 50 times to 300 times, more preferably 75 times to 280 times, and still more preferably 100 times to 260 times.
When stretching, the film may be preheated to a temperature below the stretching temperature.

  In addition, after the said extending | stretching, heat setting can be performed as needed. The heat setting temperature is usually preferably higher than the stretching temperature and lower than the melting point of the crystalline polymer fired body.

<Hydrophilic treatment process>
The hydrophilization treatment step is a step of applying a composition containing at least a radical polymerizable monomer to the exposed surface of the film and polymerizing the radical polymerizable monomer.

  There is no restriction | limiting in particular as the provision method of the composition containing the radically polymerizable monomer at least in the said hydrophilization treatment process, According to the objective, it can select suitably, For example, the method of immersing the said film in the said composition And a method of applying the film with the composition.

Next, the radically polymerizable monomer contained in the composition is polymerized by subjecting the film after application (immersion or coating) to ultraviolet irradiation or heat treatment (annealing).
When the composition containing at least a radically polymerizable monomer contains a photoradical polymerization initiator, the radically polymerizable monomer is radically polymerized by ultraviolet irradiation treatment to coat the polymer on the exposed surface of the film. .
As an illuminance condition for the ultraviolet irradiation treatment, 1.0 × 10 ² mJ / cm ^{2 to} 1.0 × 10 ⁵ mJ / cm ² is preferable, and 5.0 × 10 ² mJ / cm ^{2 to} 5.0 × 10. ⁴ mJ / cm ² is more preferable.

When the composition containing at least the radically polymerizable monomer contains a thermal radical polymerization initiator, the radically polymerizable monomer is radically polymerized by heat treatment to coat the polymer on the exposed surface of the film.
As temperature in the said heat processing, 50 to 200 degreeC is preferable, 60 to 180 degreeC is more preferable, and 70 to 160 degreeC is especially preferable.
The time for the heat treatment is preferably 1 minute to 120 minutes, more preferably 1 minute to 100 minutes, and particularly preferably 1 minute to 80 minutes.
If the temperature of the annealing treatment is less than 50 ° C. or less than 1 minute, the hydrophilic treatment may not be promoted, the polymerization reaction may not proceed, water resistance, hydrophilicity, etc. may be lost. When the temperature exceeds 200 ° C. or the time exceeds 80 minutes, the radical polymerizable monomer may be decomposed.

-Addition reaction treatment process-
The addition reaction step is a step of causing an addition reaction of a functional compound containing at least one of an ion exchange group and a chelate group to at least a part of the radical polymer.

In the addition reaction treatment step, the method for addition reaction of the functional compound to at least a part of the radical polymer is not particularly limited and may be appropriately selected depending on the purpose. For example, (i) film ( (Porous membrane) is impregnated with a mixed solution containing at least a radical polymerizable monomer and a functional compound, and subjected to a heat treatment (thermal annealing) to polymerize and coat the radical polymerizable monomer (hydrophilization treatment); A method of simultaneously causing an addition reaction between at least a part of a radical polymer and a functional compound; (ii) impregnating a mixed solution containing at least a radical polymerizable monomer and a functional compound with an ultraviolet irradiation treatment; Then, the radical polymerizable monomer is polymerized and coated, followed by heat treatment (thermal annealing), and the radical polymerization (Iii) impregnating a composition containing at least a radical polymerizable monomer with (iii) a film (porous membrane), a method of adding at least a part of the functional compound with a functional compound (sequential reaction of hydrophilization treatment and addition reaction), The radical polymer is subjected to ultraviolet irradiation treatment or heat treatment (thermal annealing) to polymerize and coat a radically polymerizable monomer, and subsequently impregnated with a solution containing a functional compound, and then heat treated (thermal annealing). And a method in which at least a part of the functional compound is subjected to an addition reaction (sequential reaction of hydrophilization treatment and addition reaction).
As an illuminance condition for the ultraviolet irradiation treatment, 1.0 × 10 ² mJ / cm ^{2 to} 1.0 × 10 ⁵ mJ / cm ² is preferable, and 5.0 × 10 ² mJ / cm ^{2 to} 5.0 × 10. ⁴ mJ / cm ² is more preferable.
As temperature in the said heat processing (thermal annealing), 50 to 200 degreeC is preferable, 50 to 180 degreeC is more preferable, 50 to 160 degreeC is especially preferable.
As time in the said heat processing, 0.5 minute-300 minutes are preferable, 0.75 minute-200 minutes are more preferable, 1 minute-100 minutes are especially preferable.

  The crystalline polymer microporous membrane of the present invention is not particularly limited and can be used for various applications, but can be suitably used as a filter for filtration described below.

(Filter for filtration)
The filter for filtration of the present invention has the crystalline polymer microporous membrane of the present invention.
When the crystalline polymer microporous membrane of the present invention is used as a filter for filtration, filtration is performed with the non-heated surface (surface having a large average pore diameter) as the inlet side. That is, the surface side having a large pore size is used as the filter surface of the filter. In this way, fine particles can be efficiently captured by performing filtration with the surface having a large average pore diameter (non-heated surface) as the inlet side.
Further, since the crystalline polymer microporous membrane of the present invention has a large specific surface area, the fine particles introduced from the surface are removed by adsorption or adhesion before reaching the minimum pore diameter portion. Therefore, clogging is unlikely to occur and high filtration efficiency can be maintained over a long period of time.

The filtration filter of the present invention can be filtered at least 5 ml / cm ² · min or more when filtration is performed at a differential pressure of 0.1 kg / cm ² .
As the shape of the filter for filtration of the present invention, a pleat type for folding the filtration membrane, a spiral type for filtering the filtration membrane, a frame-and-plate type for laminating disc-shaped filtration membranes, a filtration membrane, There is a tube type etc. which make it tubular. Among these, the pleated type is particularly preferable because the effective surface area used for filtering the filter per cartridge can be increased.
Also, it is classified into an element exchange type filter cartridge that replaces only the filter element when replacing a deteriorated filter membrane, and a capsule type filter cartridge that is processed into a filter housing with the filter housing integrated into a disposable type. Any of the filtering filters of the invention can be suitably used.

  Here, FIG. 1 is a development view showing the structure of an element exchange type pleated filter cartridge element. The microfiltration membrane 103 is folded in a state of being sandwiched by two membrane supports 102 and 104, and is wound around a core 105 having a large number of liquid collection ports. On the outside, there is an outer peripheral cover 101 that protects the microfiltration membrane. Microfiltration membranes are sealed at both ends of the cylinder by end plates 106a and 106b. The end plate is in contact with the seal portion of the filter housing (not shown) via the gasket 107. The filtered liquid is collected from the core collection port and discharged from the fluid outlet 108.

A capsule-type pleated filter cartridge is shown in FIGS.
FIG. 2 is a developed view showing the entire structure of the microfiltration membrane filter element before being assembled into the housing of the capsule filter cartridge. The microfiltration membrane 2 is folded in a sandwiched state by two supports 1 and 3 and is wound around a filter element core 7 having a large number of liquid collection ports. There is a filter element cover 6 on the outside to protect the microfiltration membrane. The microfiltration membrane is sealed by the upper end plate 4 and the lower end plate 5 at both ends of the cylinder.
FIG. 3 shows a structure of a capsule-type pleated filter cartridge in which a filter element is integrated in a housing. The filter element 10 is incorporated in a housing composed of a housing base 12 and a housing cover 11. The lower end plate 5 is sealed by a water collecting pipe (not shown) at the center of the housing base 12 via an O-ring 8. The liquid enters the housing from the liquid inlet nozzle 13, passes through the filter medium 9, is collected from the liquid collection port of the filter element core 7, and is discharged from the liquid outlet nozzle 14. The housing base 12 and the housing cover 11 are usually heat-sealed in a liquid-tight manner at the welding portion 17. An air vent 15 is provided at the upper part of the housing, and a drain 16 is provided at the lower part of the housing.

  2 and 3 show an example in which the lower end plate 5 and the housing base 12 are sealed through the O-ring 8, but the sealing between the lower end plate 5 and the housing base 12 is performed by heat fusion or adhesion. Sometimes it is done with agents. Alternatively, the seal between the housing base 12 and the housing cover 11 may be a method using an adhesive in addition to heat fusion. 1 to 3 are specific examples of the microfiltration filter cartridge, and the present invention is not limited to these drawings.

  Since the filter for filtration using the crystalline polymer microporous membrane of the present invention has such a characteristic that the filtration function is high and the life is long, the filtration device can be compactly assembled. In the conventional filtration apparatus, a large number of filtration units are used in parallel to cope with the short filtration life. However, if the filtration filter of the present invention is used, the number of filtration units used in parallel is greatly increased. Can be reduced. Moreover, since the replacement period of the filter for filtration can be extended significantly, the cost and time required for maintenance can be reduced.

  The filter for filtration of the present invention can be used in various situations where filtration is required, and is suitably used for microfiltration of gases, liquids, etc., for example, washing water for electronic industry, pharmaceutical water, pharmaceutical manufacture Used for filtration and sterilization of process water and food water. In particular, since the filter for filtration of the present invention is excellent in ion adsorption capacity, it can be effectively used, for example, in the production of ultrapure water as an ion exchange membrane or ion adsorption membrane.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
<Production of crystalline polymer microporous membrane (1)>
-Production of semi-baked film-
100 parts by mass of polytetrafluoroethylene fine powder (Daikin Industries, Ltd., “Polyflon Fine Powder F104U”) having a number average molecular weight of 6.2 million, and hydrocarbon oil (Esso Petroleum Corporation, “Isopar”) as an extrusion aid ) 27 parts by mass was added, and paste extrusion was performed in a round bar shape. This was calendered at a speed of 50 m / min with a calender roll heated to 70 ° C. to produce a polytetrafluoroethylene film. This film was passed through a hot air drying oven at 250 ° C. to remove the extrusion aid, and a polytetrafluoroethylene unfired film having an average thickness of 100 μm, an average width of 150 mm, and a specific gravity of 1.55 was produced.
One side (heated surface) of the obtained polytetrafluoroethylene unfired film was heated for 1 minute with a roll (surface material: SUS316) heated to 345 ° C. to produce a semi-fired film.

  The obtained semi-baked film was stretched between rolls by 12.5 times in the longitudinal direction at 270 ° C., and once wound on a winding roll. Then, after preheating the film to 305 ° C., both ends were sandwiched between clips and stretched 30 times in the width direction at 270 ° C. Thereafter, heat setting was performed at 380 ° C. The area stretch ratio of the obtained crystalline polymer microporous membrane was 260 times in terms of stretched area ratio.

-Functionalization processing-
5% by mass 4-hydroxybutyl acrylate glycidyl ether (manufactured by Nippon Kasei Co., Ltd.) as glycidyl acrylates and 5% by mass N- (2-hydroxyethyl) ethylenediaminetriacetic acid (manufactured by Dojin Chemical Co., Ltd.) as a functional compound having a chelate group Then, the crystalline polymer microporous film is dipped in a methanol / MEK mixed solution containing 0.1% by mass Irgacure 907 (BASF) as a photo radical polymerization initiator, and the pulled crystalline polymer microporous film is UV irradiation, followed by annealing at 150 ° C. for 10 minutes in the atmosphere. Thereafter, the film was immersed in methanol for 30 minutes, washed, and dried to produce a functionalized crystalline polymer microporous membrane (1).

(Example 2)
<Preparation of crystalline polymer microporous membrane (2)>
A functionalized crystalline polymer microporous membrane (2) was produced in the same manner as in Example 1 except that the functionalization treatment in Example 1 was replaced with the following functionalization treatment.

-Functionalization processing-
The crystalline polymer microporous membrane is immersed in a methanol / MEK mixed solution of 5% by mass acrylic acid (manufactured by TCI) and 0.1% by mass Irgacure 907 (manufactured by BASF) as a photo radical polymerization initiator, and then pulled up. The crystalline polymer microporous membrane was irradiated with UV. Subsequently, after the thionyl chloride treatment, the crystalline polymer microporous film soaked in a methanol solution of 5.0 mass% pentaethylenehexamine was annealed at 150 ° C. for 10 minutes in the air. Subsequently, the crystalline polymer microporous film soaked in a 10% by mass ethylene sulfide (manufactured by TCI) toluene solution was annealed at 100 ° C. for 10 minutes in the atmosphere. Thereafter, the film was immersed in methanol for 30 minutes, washed, and dried to produce a functionalized crystalline polymer microporous membrane (2).
In addition, the reaction compound of the said ethylene sulfide and the said pentaethylenehexamine functions as a functional compound which has a chelate group.

(Example 3)
<Preparation of crystalline polymer microporous membrane (3)>
In Example 1, 5 mass% of N- (2-hydroxyethyl) ethylenediaminetriacetic acid (manufactured by Dojin Chemical Co., Ltd.) was added to the methanol / MEK mixed solution as a functional compound having a chelate group. Crystalline polymer microporosity as in Example 1 except that 3% by mass of 3-hydroxypropanesulfonic acid (manufactured by TCI) was added as a functional compound having an ion exchange group whose reactive group is a hydroxyl group. A membrane (3) was produced.

(Comparative Example 1)
<Preparation of crystalline polymer microporous membrane (4)>
In Example 1, the crystalline polymer micro of Comparative Example 1 comprising the crystalline polymer microporous film, which is an asymmetric membrane of polytetrafluoroethylene, was prepared in the same manner as in Example 1 except that the functionalization treatment was not performed. A porous membrane (4) was produced.

(Comparative Example 2)
<Preparation of crystalline polymer microporous membrane (5)>
In Example 2, instead of using a crystalline polymer microporous membrane, a polytetrafluoroethylene microporous membrane (manufactured by Japan Gore-Tex: Symmetric membrane) was used in the same manner as in Example 2 A crystalline polymer microporous membrane (5) of Comparative Example 2 was produced.

(Comparative Example 3)
<Preparation of crystalline polymer microporous membrane (6)>
A crystalline polymer microporous membrane (6) of Comparative Example 3 was produced in the same manner as in Example 1 except that the functionalization treatment in Example 1 was replaced with the following functionalization treatment. That is, instead of coating with a radical polymer obtained by polymerizing a composition containing a radical polymerizable monomer and subjecting at least a part of the radical polymer to an addition reaction with a functional compound, a previously polymerized radical polymer (polymer) And a functional compound was added to at least a part of the radical polymer.

-Functionalization processing-
A crystalline polymer microporous membrane is immersed in a MEK solution of a radical polymer of 5% by mass of 4-hydroxybutyl acrylate glycidyl ether and dried, followed by 5% by mass of N- (2-hydroxyethyl) ethylenediaminetriacetic acid. The crystalline polymer microporous film soaked in a methanol solution (manufactured by Dojin Chemical Co., Ltd.) was annealed at 150 ° C. for 10 minutes in the air.
This produced a functionalized crystalline polymer microporous membrane (6).

<Evaluation>
The crystalline polymer microporous membranes produced in Examples 1 to 3 and Comparative Examples 1 to 3 were evaluated as follows.

<< Measurement of average pore diameter and evaluation of hole shape >>
Each crystalline polymer microporous membrane in Examples 1 to 3 and Comparative Examples 1 to 3 was cut along the longitudinal direction of the crystalline polymer microporous membrane, and in the thickness direction of the crystalline polymer microporous membrane. The cut surface is taken with a scanning electron microscope (Hitachi S-4000 type, vapor deposition is Hitachi E1030 type, both manufactured by Hitachi, Ltd.) and a photograph of the film surface (SEM photo, magnification 1,000 to 5,000 times) The obtained photograph is taken into an image processing apparatus (main body name: Nippon Avionics Co., Ltd., TV image processor TVIP-4100II, control software name: Ratok System Engineering Co., Ltd., TV image processor image command 4198), and crystalline polymer fiber I got an image consisting of only. For the obtained image, 100 pore diameters were measured and processed to obtain an average pore diameter.

For easy understanding of the shape of the hole in the cut surface in the thickness direction of the crystalline polymer microporous film, a description will be given using schematic diagrams.
4A is a diagram schematically showing a cut surface of a crystalline polymer microporous membrane having a symmetrical hole before functionalization treatment (before hydrophilization treatment and addition reaction treatment) in Comparative Example 2. FIG.
In FIG. 4A, the average pore diameter on the first surface of the crystalline polymer microporous membrane 40 having a symmetrical hole before the functionalization treatment (before the hydrophilization treatment and addition reaction treatment) is d _1, and the average on the second surface is When the hole diameter was d ₂ , the ratio (d ₁ / d ₂ ) between d ₁ and d ₂ in the observed SEM image was 1.0.
FIG. 4B is a diagram schematically showing a cut surface of a crystalline polymer microporous membrane having a symmetrical hole after functionalization treatment (after hydrophilization treatment and addition reaction treatment) in Comparative Example 2.
The average pore diameter on the first surface of the crystalline polymer microporous membrane 40 having a symmetrical hole after the functionalization treatment (hydrophilization treatment and addition reaction treatment, coating portion 45) in FIG. 4B is defined as d ₁ ′. 'when a, _{d 1} in the observed SEM images' average pore diameter in the second surface _{d 2'} ratio of _{(d 1} 'and _{d 2} / _{d 2')} was 1.0.
Therefore, (d ₁ ′ / d ₂ ′) / (d ₁ / d ₂ ) in Comparative Example 2 was 1.0. Thus, in the crystalline polymer microporous membrane having the symmetric pores of Comparative Example 2 not subjected to the asymmetric heating treatment, the ratio (d ₁ / d ₂ ) before and after the functionalization treatment (hydrophilization treatment and addition reaction treatment) And the ratio (d ₁ '/ d ₂ ') were found to be unchanged.

Next, FIG. 5A is a diagram schematically showing a cut surface of a crystalline polymer microporous membrane having asymmetric pores before functionalization treatment (before hydrophilization treatment and addition reaction treatment) in Example 1. FIG.
In FIG. 5A, the average pore diameter on the first surface of the crystalline polymer microporous membrane 50 having asymmetric pores before functionalization treatment (before hydrophilization treatment and addition reaction treatment) is d _3, and the average on the second surface is when the pore size was _{d 4,} the ratio of _{d 3} and _{d 4} in the observed SEM images _(d 3 / _{d 4)} was 15.
5B is a diagram schematically showing a cut surface of a crystalline polymer microporous membrane having asymmetric pores after functionalization treatment (after hydrophilization treatment and addition reaction treatment) in Example 1. FIG.
(After hydrophilization and addition reaction treatment, the covering portion 55) After this functionalization process in Figure 5B the average pore diameter in the first surface of the crystalline polymer microporous membrane 50 having asymmetric pores of the d _{3 ',} the 'when a, _{d 3} in the SEM image observed' an average pore diameter in the second surface _{d 4} 'ratio of _{(d 3'} and _{d 4} / _{d 4} ') was 15.9.
Therefore, (d ₃ ′ / d ₄ ′) / (d ₃ / d ₄ ) in Example 1 was 1.06.

The ratio (d ₃ ′ / d ₄ ′) of the crystalline polymer microporous membrane after the functionalization treatment (after hydrophilization treatment and addition reaction treatment) in Example 1 and before the functionalization treatment in Example 1 (hydrophilicity) From the comparison with the ratio (d ₃ / d ₄ ) in the crystalline polymer microporous membrane before the functionalization treatment and the addition reaction treatment, the first surface was obtained before the functionalization treatment (before the hydrophilic treatment and the addition reaction treatment). It was found that the ratio of the average pore diameter on the (non-heated surface) and the average pore diameter on the second surface (heated surface) can be increased.
This result is contrary to the expectation before SEM image observation, in addition to the fact that the average pore diameter of the crystalline polymer microporous film 50 continuously changes from the first surface to the second surface, This is based on the fact that the thickness of the covering portion 55 after the functionalization treatment using the functional polymer continuously changes in the direction in which the thickness increases from the first surface toward the second surface. This is because the coating portion 55 is attached to a denser portion on the second surface (heated surface) side of the crystalline polymer microporous membrane, and thicker than the coarsely filtered portion on the first surface (non-heated surface) side. This is considered to be because a significant asymmetric structure can be formed in which the average particle diameter continuously changes from the first surface to the second surface.
From these results, in the crystalline polymer microporous membrane (1) in Example 1, in addition to being excellent in hydrophilicity, the ratio of the average pore size on the first surface to the average pore size on the second surface Therefore, it has been clarified that the filtration life until clogging (filtration flow rate) can be greatly improved.

Similarly, in Example 2, a membrane having an asymmetric pore of d ₃ / d ₄ = 15 was subjected to functionalization treatment (after hydrophilization treatment and addition reaction treatment), and d ₃ ′ / d ₄ ′ = 15. 6 and (d ₃ ′ / d ₄ ′) / (d ₃ / d ₄ ) = 1.04.
Likewise, in Example _3, the asymmetric membrane having d _{3 /} d 4 = 15, after function processing (hydrophilic treatment and after the addition reaction _{treatment), d 3 '/ d 4} ' = 15. 9 and (d ₃ ′ / d ₄ ′) / (d ₃ / d ₄ ) = 1.06.
Similarly, in Comparative Example 1, since the functionalization treatment (hydrophilization treatment) was not performed on the membrane having the asymmetric pores d ₃ / d ₄ = 15, there was no change in the pore diameter.
Similarly, in Comparative Example _3, the asymmetric membrane having d _{3 /} d 4 = 15, after function processing (after hydrophilization and addition reaction _{treatment), d 3 '/ d 4} ' = 15. 3 and (d ₃ ′ / d ₄ ′) / (d ₃ / d ₄ ) = 1.02.

<< Hydrophilicity evaluation >>
Next, hydrophilicity was evaluated about each produced crystalline polymer microporous film | membrane of Examples 1-3 and Comparative Examples 1-3.
The hydrophilicity of each crystalline polymer microporous membrane was evaluated with reference to Japanese Patent No. 3075421. Specifically, the evaluation was performed as follows.
The initial hydrophilicity was evaluated according to the following criteria as to whether or not water droplets were absorbed by dropping water droplets from the height of 5 cm onto the sample surface. The results are shown in Table 1.
〔Evaluation criteria〕
A: Absorbed immediately B: Absorbed spontaneously C: Absorbed only when pressurized or not absorbed, but contact angle decreased D: Not absorbed That is, it repels water. This D evaluation is specific to porous fluororesin materials.

<< filtration test >>
A filtration test was performed on the crystalline polymer microporous membranes of Examples 1 to 3 and Comparative Examples 1 to 3. First, an aqueous solution containing 0.01% by mass of polystyrene latex (average particle size 1.5 μm) is filtered at a differential pressure of 10 kPa, and the permeation amount until clogging is shown in Table 1.

<< Flow test >>
About each crystalline polymer microporous film | membrane of Examples 1-3 and Comparative Examples 1-3, the flow rate test was done as follows.
The flow rate was measured according to JIS K3831 under the following conditions. The type of the test method was “Pressurized filtration test method”, and the sample was cut into a circle having a diameter of 13 mm and set in a stainless steel holder for measurement. Ion exchange water was used as the test solution, and the time required to filter 100 mL of the test solution at a pressure of 10 kPa was measured, and the flow rate (L / min · m ² ) was calculated. The results are shown in Table 1.

From the results in Table 1, it can be seen that Examples 1 to 3 and Comparative Examples 2 to 3 have hydrophilicity, and Comparative Example 1 has no hydrophilicity.
In the filtration test, the crystalline polymer microporous membrane of Comparative Example 1 was not hydrophilic and could not be measured. In Comparative Example 2-3 did not exceed 100 mL / cm ^2.
In contrast, each of the crystalline polymer microporous membranes of Examples 1 to 3 does not require a pre-hydrophilization treatment with isopropanol, which has been conventionally required, and can be filtered to 100 mL / cm ² or more. It has been found that the filtration life is improved by using the crystalline polymer microporous membrane of the invention.
Also in the flow rate test, the crystalline polymer microporous membrane of Comparative Example 1 was not hydrophilic and could not be measured, and Comparative Examples 2 to 3 did not exceed 100 L / min · m ² . On the other hand, each crystalline polymer microporous membrane of Examples 1 to 3 is 100 L / min · m ² or more, and the flow rate is greatly improved by using the crystalline polymer microporous membrane of the present invention. I found out.
The reason why the filtration life and the flow rate are improved is considered to be that the foam permeability is improved and the clogging by the foam is reduced.

<< Evaluation of water resistance >>
The process of passing 200 mL of water under a pressure condition of 100 kPa was repeated 5 times for each crystalline polymer microporous membrane in Examples 1 to 3 and Comparative Examples 1 to 3. Drying was performed after each pass.
Evaluation of water resistance is evaluated based on the judgment criteria (A to D) in the evaluation of hydrophilicity for each of the crystalline polymer microporous membranes in Examples 1 to 3 and Comparative Examples 1 to 3 that have undergone the above process. It was done by doing. The results are shown in Table 2.

In Table 2, “Unmeasurable” indicates that evaluation was not possible because of poor hydrophilicity.

<< Evaluation of ion adsorption performance >>
Evaluation of ion adsorption performance referred to JP-A-2-187136 for the crystalline polymer microporous membranes of Examples 1 to 3 and Comparative Examples 1 to 3. Specifically, 1 L of an aqueous solution containing 10 ppm of each metal ion (silver, sodium) was prepared, and 10 mL of the aqueous solution was passed through each crystalline polymer microporous membrane in Examples 1 to 3 and Comparative Examples 1 to 3. The measurement was performed by measuring the concentration of metal ions contained in the aqueous solution after permeation. The results are shown in Table 3.

In Table 3, “Unmeasurable” indicates that evaluation was not possible because of poor hydrophilicity.

Example 4
-Filter cartridge-
The crystalline polymer microporous membrane prepared in Example 1 is sandwiched between two polypropylene nonwoven fabrics, pleated to a pleat width of 10.5 mm, 138 folds are taken and rolled into a cylindrical shape, and the alignment is made. The eyes were welded with an impulse sealer. Both ends of the cylinder were cut off by 2 mm, and the cut surfaces were heat welded to a polypropylene end plate to finish an element exchange type filter cartridge.
Since the built-in crystalline polymer microporous membrane is hydrophilic, the produced filter cartridge of the present invention does not require complicated pre-hydrophilic treatment in the aqueous treatment. Moreover, since crystalline polymer is used, it is excellent in solvent resistance. Further, since the hole portion has an asymmetric structure, it has a long life with a large flow rate and hardly clogged.

  The crystalline polymer microporous membrane of the present invention and a filter for filtration using the same are excellent in heat resistance and chemical resistance, and can be used in various situations where filtration is required. It is suitably used for microfiltration of liquids and the like, and can be widely used for filtration, sterilization, high temperature filtration and the like of washing water for electronics industry, pharmaceutical water, water for pharmaceutical manufacturing processes, food water and the like.

DESCRIPTION OF SYMBOLS 1 Primary side support 2 Microfiltration membrane 3 Secondary side support 4 Upper end plate 5 Lower end plate 6 Filter element cover 7 Filter element core 8 O-ring 9 Filter media 10 Filter element 11 Housing cover 12 Housing base 13 Liquid inlet nozzle 14 Liquid Outlet nozzle 15 Air vent 16 Drain 17 Welding part 101 Outer cover 102 Membrane support 103 Microfiltration membrane 104 Membrane support 105 Core 106a, 106b End plate 107 Gasket 108 Liquid outlet

Claims (11)

A crystalline polymer microporous membrane having an asymmetric pore structure,
At least a part of the exposed surface of the crystalline polymeric microporous membrane is coated with a radical polymer obtained by polymerizing a composition containing a radical polymerizable monomer, and at least a part of the radical polymer has an ion exchange group. And a functional compound containing at least one of a chelate group, and the radical polymerizable monomer is at least one selected from acrylate, methacrylate, acrylamide, acrylic acid and derivatives thereof A crystalline polymer microporous membrane.   The crystalline polymer micropore according to claim 1, wherein the radical polymerizable monomer contains at least one of a carboxyl group, an amino group, a hydroxyl group, an epoxy group, an acrylamide group, an isocyanate group, and an acid chloride group. Sex membrane.   The crystalline polymer microporous membrane according to any one of claims 1 to 2, wherein the functional compound is a compound having a reactive group with a radical polymer.   The average hole diameter in the first surface is larger than the average hole diameter in the second surface, and has a plurality of hole portions whose average hole diameter continuously changes from the first surface toward the second surface. Item 4. The crystalline polymer microporous membrane according to any one of Items 1 to 3. The ratio (d ₃ / d ₄₎ of the average pore diameter d _{3 on} the first surface of the crystalline polymer microporous film before coating with the radical polymerizable monomer polymer on the exposed surface and the average pore diameter d _{4 on} the second surface )When,
The ratio (d ₃ ′) of the average pore diameter d ₃ ′ on the first surface of the crystalline polymer microporous membrane after coating the exposed surface with the fluorosurfactant and the average pore diameter d ₄ ′ on the second surface / D ₄ ′) satisfies the following formula: (d ₃ ′ / d ₄ ′) / (d ₃ / d ₄ )> 1 The crystalline polymer microporosity according to any one of claims 1 to 4 film.   6. The crystalline polymer microporous membrane according to claim 1, wherein the crystalline polymer is polytetrafluoroethylene. A hydrophilization step of applying a composition containing a radical polymerizable monomer to the exposed surface of the crystalline polymer microporous film having an asymmetric pore structure, and polymerizing the radical polymerizable monomer;
An addition reaction treatment step in which a functional compound containing at least one of an ion exchange group and a chelate group is added to a part of the radical polymer, and the radical polymerizable monomer is an acrylate, methacrylate, acrylamide, acrylic A method for producing a crystalline polymer microporous membrane, which is at least one selected from acids and derivatives thereof. An asymmetric heating step of heating one surface of the crystalline polymer film to form a semi-baked film having a temperature gradient in the thickness direction of the film;
A stretching step of stretching the semi-baked film to form a crystalline polymer microporous film having an asymmetric pore structure;
The method for producing a crystalline polymer microporous membrane according to claim 7, further comprising:   The radically polymerizable monomer contains at least one of a carboxyl group, an amino group, a hydroxyl group, an epoxy group, an acrylamide group, an isocyanate group, and an acid chloride group, according to any one of claims 7 to 8. A method for producing a crystalline polymer microporous membrane.   The method for producing a crystalline polymer microporous membrane according to any one of claims 7 to 9, wherein the functional compound is a compound having a reactive group with a radical polymer.   A filter for filtration, comprising the crystalline polymer microporous membrane according to claim 1.