JP2009142799A - Porous membrane and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a porous membrane having a uniform porosity in the thickness direction, and the porous membrane. <P>SOLUTION: The method for manufacturing the porous membrane includes: forming a membrane from a dope solution including (a) a polyether sulfone resin, (b) a hydrophilic polymer, and (c) a solvent; humidifying and hardening the dope solution; and removing (b) the hydrophilic polymer and (c) the solvent to form the porous membrane of (a) the polyether sulfone resin. In the method, (b) the hydrophilic polymer and (c) the solvent is used at a rate of the hydrophilic polymer to the solvent of 1.5/1 to 2.7/1, steam is supplied to the dope solution for humidification at a rate of 1 to 1,000 g/m<SP>2</SP>*s, and (a) the polyether sulfone resin is hardened, thus the porous membrane is manufactured. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a porous film having a uniform porosity in the thickness direction, a method for producing the same, and a laminate of the porous film and a substrate.

  Since polyethersulfone-based resins are excellent in heat resistance, mechanical strength, and chemical resistance, they are attracting attention as resins constituting the porous membrane, and methods for producing the porous membrane are also being studied.

  Japanese Patent No. 3150717 (Patent Document 1) discloses a method for producing a polysulfone-based resin permselective membrane from a membrane-forming stock solution in which a polysulfone-based resin, polyvinylpyrrolidone and a solvent are mixed, and the molecular weight of polyvinylpyrrolidone is 300,000 or more. A method for producing a polysulfone-based resin permselective hemodialysis and / or blood filtration membrane is disclosed. In the method described in this document, hydrophilicity can be imparted to the resin by adding a high molecular weight polyvinyl pyrrolidone even with a small amount. However, high molecular weight polyvinyl pyrrolidone has low solubility in a solvent and is likely to become insoluble by heating, so that it is difficult to obtain a uniform film forming stock solution, and the resulting film often becomes an asymmetric film. Further, the high molecular weight polyvinyl pyrrolidone has a problem that it is difficult to remove after forming a porous film and remains inside the film.

  As another method for producing a porous membrane, for example, JP-A-55-102416 (Patent Document 2) discloses a solution obtained by dissolving a polymer substance (polysulfone resin) in a good solvent (A). Alternatively, after casting into a tubular shape, at least one side thereof is brought into contact with the vapor of the solvent (B) having poorer solubility than the good solvent (A), and then the good solvent (A) and the solvent (B The separation membrane is immersed in a coagulating liquid (C) that is compatible with the polymer substance and coagulates the polymer substance.

Japanese Patent Publication No. 6-76510 (Patent Document 3) discloses a polysulfone microporous membrane having a minimum pore size layer only in the inside of the membrane and having an asymmetric pore size distribution continuously changing from the front surface to the back surface of the membrane. It is disclosed. The polysulfone microporous membrane is obtained by, for example, applying air having an absolute humidity of ₂ gH ₂ O / kg Air or more to the casting surface at a wind speed of 0.2 m / sec or more on a membrane forming stock solution cast on a support. It can be manufactured by adjusting the evaporation amount of the solvent vapor and the non-solvent vapor absorption amount from the atmosphere.

JP-B-5-85576 (Patent Document 4) describes a film-forming stock solution obtained by adding a lubricant and a non-solvent (polymer poor solvent) to a polymer and dissolving it in a solvent (good polymer solvent). Cast on a casting support in a solution state, and evaporate the solvent and absorb moisture in the air by casting the temperature-controlled humid air or infrared radiation and temperature-controlled humid air on the cast liquid film. After causing the cervation, the liquid film is immersed in a coagulation bath to perform phase separation and coagulation to form a microporous film, and then the microporous film is peeled off from the casting support. A method for producing a microporous membrane is disclosed. In this method, the evaporation of the solvent and the amount of the non-solvent absorbed from the atmosphere are controlled before the film-forming stock solution is solidified, and the non-surface area between the front surface and the back surface of the film is 8 m ² / g or more. A film is formed.

  However, the porous films obtained in Patent Documents 2 to 4 are asymmetric films (heterogeneous films) in which a dense layer is formed on the surface of the film and the porosity changes in the thickness direction. In conventional manufacturing methods, it is difficult to adjust the porosity, and usually the majority is an asymmetric membrane (heterogeneous membrane). In the asymmetric membrane, a dense layer is formed on the surface, and a porous support layer is formed on the inside and the back surface. In such an asymmetric membrane, salts and the like can be excluded in the dense layer, so that although it is suitable for uses such as separation (for example, separation membranes, filtration membranes, dialysis membranes, especially separation membranes for desalting), It is not suitable for applications in which various fillers are filled (or impregnated).

In Japanese Patent Publication No. 5-76331 (Patent Document 5), a hydrophobic polymer (for example, polyethersulfone, etc.) is dissolved in a polar aprotic solvent, and polyethylene glycol 400 is further added, followed by stirring. A method is described in which the prepared mixture is cast, exposed to air of about 50-80% relative humidity at room temperature, and then immersed in water to completely coagulate the hydrophobic polymer to produce a filtration membrane. In this method, the proportion of hydrophobic polymer is about 10-13% of the mixture, the proportion of polar aprotic solvent is about 17-20%, and the proportion of polyethylene glycol is 65-70%. It is described that it is good. However, in the method of this document, since polyethylene glycol is used in excess relative to the amount of polar aprotic solvent used, the solubility of the hydrophobic polymer is reduced, and a uniform film-forming solution (or dope) is produced. Difficult to get. Furthermore, in the method of this document, the amount of moisture applied to the film is small, and it takes time to completely solidify the hydrophobic polymer, resulting in poor industrial productivity.
Patent 3150717 (Claims) JP 55-102416 A (Claims) Japanese Patent Publication No. 6-76510 (claims, page 3, left column, lines 20 to 26) Japanese Patent Publication No. 5-85576 (Claims) Japanese Patent Publication No. 5-76331 (page 6, left column, line 31 to right column, line 9)

  Accordingly, an object of the present invention is to provide a method for producing a porous film having a uniform porosity in the thickness direction and the porous film.

  Another object of the present invention is to provide a method for producing a porous membrane that is homogeneous in the thickness direction in an industrially efficient and simple manner and the porous membrane.

  Still another object of the present invention is to provide a method for producing a porous membrane having a uniform and high porosity in the thickness direction and suitable for impregnation with a filler, and the porous membrane. .

  Another object of the present invention is to provide a porous film excellent in adhesion (or adhesiveness) to a base material (for example, a base material composed of a polyethersulfone resin), and the porous film and the base material. It is in providing the method of manufacturing this laminated body, and its laminated body.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have used (b) a hydrophilic polymer and (c) a solvent at a specific ratio and formed a dope (or a film-forming stock solution). It has been found that when a film is humidified under specific conditions, a porous film (homogeneous film) having a uniform porosity in the thickness direction can be produced efficiently and simply, and the present invention has been completed.

That is, in the method of the present invention, a dope containing (a) a polyethersulfone-based resin, (b) a hydrophilic polymer, and (c) a solvent is formed, humidified and solidified, and the (b) hydrophilic And (c) the solvent is removed to produce a porous membrane composed of the (a) polyethersulfone resin, wherein (b) the hydrophilic polymer and (c) the solvent And the former / the latter (weight ratio) = 1.5 / 1 to 2.7 / 1, and water is supplied to the dope at a rate of 1 to 1000 g / m ² · second to humidify the dope. Then, the (a) polyethersulfone resin is solidified to produce a porous membrane.

In the method, the (b) hydrophilic polymer and the (c) solvent are used at a ratio of the former / the latter (weight ratio) = 1.6 / 1 to 2.5 / 1, and with respect to the dope. The steam may be supplied and humidified at a rate of 5 to 300 g / m ² · sec. In the method, the humidification time may be about 0.1 to 10 seconds. Further, the content of the (a) polyethersulfone resin is about 5 to 20% by weight based on the total amount of (a) the polyethersulfone resin, (b) the hydrophilic polymer, and (c) the solvent. It may be. Further, the number average molecular weight of the hydrophilic polymer (b) may be about 100 to 2,000.

  In the method, the dope may be cast on a substrate to form a film, and the porous film may be separated from the substrate. Moreover, the dope may be applied to a base material to form a film, and a porous film laminated on the base material may be manufactured. The base material may be composed of a polyethersulfone resin.

  The present invention also includes a porous membrane obtained by the above production method. The porosity of the porous film may be about 40 to 90%. The porous membrane may further contain a filler in the pores of the porous membrane.

  Furthermore, the present invention includes a laminate composed of a substrate and the porous film laminated on the substrate. The said laminated body WHEREIN: The thickness of the said porous membrane is about 1-200 micrometers, and the said base material may be comprised with the polyether sulfone type resin.

  In the present invention, when (b) a hydrophilic polymer and (c) a solvent are used at a specific ratio, and the formed dope (or film-forming stock solution) is humidified under specific conditions, it is uniform in the thickness direction. A porous membrane (homogeneous membrane) having a high porosity can be produced. The porous membrane can be produced efficiently and simply industrially because a specific dope may be humidified under specific conditions. Since the porous membrane thus produced is homogeneous in the thickness direction and has a high porosity, it is useful as a support for impregnating the filler. Furthermore, since the porous film is excellent in adhesion (or adhesiveness) with a base material (particularly, a base material made of a polyethersulfone-based resin), the laminate with the base material is stable. It can be manufactured in the form.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings as necessary.

[Method for producing porous membrane]
The porous membrane of the present invention is (a) a porous membrane formed by agglomerating a polyethersulfone-based resin in the form of fine particles, and (a) the polyethersulfone-based resin, (b) a hydrophilic polymer, (C) A dope (or a film-forming stock solution) containing a solvent can be formed, humidified and solidified.

((A) polyethersulfone resin)
(A) The polyethersulfone resin has the following formula (1)

(In the formula, R ₁ and R ₂ are the same or different and are hydrocarbon group, haloalkyl group, hydroxyl group, alkoxy group, haloalkoxy group, carboxyl group, alkoxycarbonyl group, acyl group, amino group, substituted amino group, halogen, An atom, a nitro group, a cyano group, or a heterocyclic group is shown, and m and n are the same or different and are integers of 0 to 4.)
It is a polymer which has a unit represented by these. The unit includes a substituted unit in which a phenylene group is substituted with one or a plurality of substituents, as well as an unsubstituted unit in which m and n are 0, in which the phenylene group is not substituted. (A) The polyether sulfone resin is a non-substituted unit or a homopolymer of a substituted unit, a copolymer of an unsubstituted unit and a substituted unit, a copolymer of a plurality of types of substituted units, and the like. May be.

Examples of the substituents R ₁ and R ₂ include a hydrocarbon group [for example, an alkyl group (for example, a C _1-10 alkyl group such as a methyl group or an ethyl group), a cycloalkyl group (for example, a C group such as a cyclohexyl group). _5-10 cycloalkyl group), aryl group (for example, C _6-10 aryl group such as phenyl group)], haloalkyl group, hydroxyl group, alkoxy group (for example, C _1-10 alkoxy group such as methoxy group) , Haloalkoxy group, carboxyl group, alkoxycarbonyl group (for example, C _1-10 alkoxycarbonyl group such as methoxycarbonyl group), acyl group (for example, C _2-5 acyl group such as acetyl group), amino group, substitution Amino group, halogen atom, nitro group, cyano group, heterocyclic group (nitrogen atom-containing heterocyclic ring such as pyridyl group) And the like). Preferred substituents R ₁ and R ₂ are an alkyl group, an alkoxycarbonyl group, and the like, and a more preferred substituent is a C _1-4 alkyl group (particularly a methyl group) such as a methyl group.

The substitution numbers m and n of the substituents R ₁ and R ₂ are the same or different and are 0 to 4, preferably 0 to 2, more preferably 0 or 1, and m and n are usually 0. In addition, the substitution position of the substituents R ₁ and R ₂ is not particularly limited.

  The number average molecular weight of the (a) polyethersulfone resin may be about 1,000 to 100,000, preferably about 3,000 to 50,000, and more preferably about 5,000 to 30,000.

  When the viscosity of the (a) polyethersulfone-based resin is measured in a 20 wt% N-methyl-2-pyrrolidone solution using a B-type viscometer under conditions of 6 rpm and 23 ° C., for example, 100 to It may be about 10,000 cps (0.1 to 10 Pa · s), preferably about 300 to 9000 cps (0.3 to 9 Pa · s), and more preferably about 500 to 8000 cps (0.5 to 8 Pa · s). When the viscosity is less than 100 cps (0.1 Pa · s), the obtained dope easily flows and the thickness of the formed porous film becomes thin. On the other hand, when the viscosity exceeds 10,000 cps (10 Pa · s), it is difficult to obtain a uniform dope.

((B) hydrophilic polymer)
(B) The hydrophilic polymer (or water-soluble polymer or hydrophilic oligomer) is immiscible with the (a) polyethersulfone resin, (c) is miscible with the solvent, and is a film forming environment. There is no particular limitation as long as it is liquid (or molten) at the temperature of the film-forming stock solution (for example, the step of casting or coating the film-forming stock solution). Such (b) hydrophilic polymers include hydrophilic groups or units (carboxyl groups or salts thereof, sulfonic acid groups or salts thereof, hydroxyl groups, amide groups, basic nitrogen atom-containing groups or salts thereof, ether groups. , An oxyalkylene unit or the like) (polymer or monomer having a hydrophilic group or unit or a copolymer of a monomer having a hydrophilic group or unit and a copolymerizable monomer) ), Polysaccharides (eg, cellulose derivatives, alginic acids, etc.). Examples of the copolymerizable monomer include olefin monomers (for example, α-C _2-6 olefins such as ethylene, propylene, 1-butene and 2-butene), (meth) acrylic monomers, and the like. Monomers [eg (meth) acrylic acid C _1-6 alkyl esters such as (meth) acrylic acid, methyl (meth) acrylate and ethyl (meth) acrylate)], vinyl esters (eg vinyl acetate etc. ), Unsaturated polycarboxylic acids or acid anhydrides thereof (for example, maleic anhydride, maleic acid, etc.), dienes (butadiene, isoprene, etc.) and the like.

(B) The hydrophilic polymer is, for example, a polymer having a carboxyl group or a salt thereof (for example, a (meth) acrylic monomer having a carboxyl group (or a salt thereof) such as poly (meth) acrylic acid alone. Or a copolymer or a salt thereof (for example, alkali metal salt, ammonium salt, organic amine salt, etc.), (meth) acrylic acid-vinylsulfonic acid copolymer, (meth) acrylic acid-methyl methacrylate copolymer, etc. A copolymer of a (meth) acrylic monomer having a carboxyl group (or a salt thereof) and a copolymerizable monomer or a salt thereof]; a polymer having a sulfonic acid group or a salt thereof [eg, ethylenesulfone Monomers or copolymers of sulfonic acid groups such as acids and styrene sulfonic acids, copolymers of sulfonic acid group monomers and copolymerizable monomers, or salts thereof] Polymers having hydroxyl groups [for example, monomers or copolymers of monomers such as polyethylene glycol mono (meth) acrylate, copolymers of monomers having hydroxyl groups and copolymerizable monomers, vinyl alcohol A polymer having an amide group [for example, a monomer or a copolymer of a monomer such as (meth) acrylamide, a copolymer of a monomer having an amide group and a copolymerizable monomer] Etc.]; a polymer having a basic nitrogen atom-containing group [for example, a monomer alone or a copolymer such as N-dimethylaminoethyl (meth) acrylate and vinylpyrrolidone, a monomer having a basic nitrogen atom, and Copolymer with copolymerizable monomer or salt thereof (for example, inorganic acid such as hydrochloric acid, organic acid such as acetic acid)]; polymer having ether group [for example, vinyl alkyl ether For example, vinyl ether monomers or copolymers such as vinyl methyl ether), copolymers of vinyl ether monomers and copolymerizable monomers (maleic anhydride, (meth) acrylic acid, etc.) A polymer having an oxyalkylene unit [for example, a monomer having an oxyalkylene unit such as an oxyethylene unit or a copolymer thereof, a monomer having an oxyalkylene unit and a copolymerizable monomer] Copolymers, etc.]; polysaccharides {e.g., cellulose ethers [e.g., alkyl celluloses (e.g., C _1-6 alkyl celluloses, such as methyl cellulose); hydroxyalkyl celluloses (e.g., hydroxy C _2-6 alkyl celluloses, such as hydroxyethyl cellulose, etc.) ); Carboxyalkyl cellulose (eg If, cellulose derivatives such as carboxy C _1-6 alkyl cellulose), etc.], such as carboxymethylcellulose; linear heteropolymeric comprising as constituent units and alginic acids [alginate (D-mannuronic acid and L- guluronic acid) or Salt (for example, an inorganic salt such as an ammonium salt, an alkali metal salt, an alkaline earth metal salt, a transition metal salt, etc.)] and the like}. Among these (b) hydrophilic polymers, from the viewpoint of elution, vinyl alcohol polymers, vinyl pyrrolidone polymers, vinyl ether polymers, polymers having oxyalkylene units (polyalkylene glycol polymers). Are preferably used.

  Examples of the vinyl alcohol polymer include saponified vinyl ester polymers (single or copolymer) such as polyvinyl alcohol (fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol), partially acetalized polyvinyl alcohol, ethylene- A vinyl alcohol copolymer, a vinyl alcohol-ethylene sulfonic acid copolymer, a vinyl alcohol-maleic acid copolymer, and the like are included. Of these vinyl alcohol polymers, polyvinyl alcohol is usually used in many cases.

  Examples of the vinyl pyrrolidone polymer include a homopolymer of vinyl pyrrolidone (polyvinyl pyrrolidone), a copolymer of vinyl pyrrolidone and a copolymerizable monomer (for example, a copolymer of vinyl acetate and / or vinyl caprolactam, etc. Etc.). Of these vinylpyrrolidone polymers, polyvinylpyrrolidone is usually used in many cases.

  Examples of the vinyl ether polymer include a vinyl alkyl ether homopolymer (polyvinyl alkyl ether) or a copolymer, a copolymer of vinyl alkyl ether and a copolymerizable monomer (for example, maleic anhydride, (meta And a copolymer with acrylic acid, etc.). Of these vinyl ether polymers, polyvinyl alkyl ethers such as polyvinyl methyl ether are usually used in many cases.

Examples of the polyalkylene glycol polymer include a polymer having an oxyethylene unit, for example, a homopolymer of ethylene oxide (polyethylene oxide or polyethylene glycol), a copolymer of ethylene oxide and C _3-4 alkylene oxide (for example, Polyoxyethylene-polyoxypropylene block copolymer, etc.). Of these polyalkylene glycol polymers, polyethylene glycol is usually used in many cases.

  (B) When the hydrophilic polymer is a copolymer, the bonding form is not particularly limited, and may be random copolymerization, block copolymerization, or graft copolymerization. (B) A hydrophilic polymer can be used individually or in combination of 2 or more types.

  The number average molecular weight of the (b) hydrophilic polymer can be selected from about 100 to 100,000 (preferably 1,000 to 50,000, more preferably 2,000 to 30,000). From the point that it can be liquefied (or melted) even at a relatively low temperature, the increase in viscosity can be suppressed, (c) it has excellent solubility in a solvent, and can be easily removed with a coagulation solvent described later after film formation. ) The number average molecular weight of the hydrophilic polymer is preferably relatively small, and may be the molecular weight of the oligomer region. For example, the number average molecular weight of the (b) hydrophilic polymer is 100 to 2,000, preferably 120 to 1,000, more preferably 130 to 800, and particularly about 140 to 600 (for example, 150 to 500). There may be.

((C) solvent)
(C) The solvent is not particularly limited as long as it can dissolve both the (a) polyethersulfone-based resin and (b) the hydrophilic polymer, but the (a) polyethersulfone-based resin and (b) hydrophilic In general, aprotic polar solvents {for example, cyclic ethers such as tetrahydrofuran, dioxolane, dioxane and trioxane; ketones such as acetone; and cyclic molecules such as γ-butyrolactone (GBL) Esters (lactones); nitrogen-containing solvents [for example, nitriles such as acetonitrile, propionitrile, benzonitrile; amides such as dimethylformamide, dimethylacetamide; pyrrolidone-containing solvents such as N-methyl-2-pyrrolidone, hexamethyl Phosphamide, etc.]; sulfur-containing solvents [e.g. Sulfoxides such as Rusuruhokishido; often sulfolane, etc.]}. (C) The solvent may be used alone or in combination of two or more.

  Preferred solvents include sulfoxides (eg, dimethyl sulfoxide), nitrogen-containing solvents [eg, amides (eg, dimethylformamide, dimethylacetamide, etc.), pyrrolidone-containing solvents (eg, N-methyl-2-pyrrolidone, etc.)] It is.

(Ratio of each component)
The content of (a) the polyethersulfone resin is 5 to 20% by weight, preferably 7 with respect to the total amount of (a) the polyethersulfone resin, (b) the hydrophilic polymer, and (c) the solvent. It may be ˜18% by weight, more preferably 9 to 16% by weight, especially about 10 to 15% by weight. If the content of the (a) polyethersulfone-based resin is too small, it will not become porous. On the other hand, if the content of the (a) the polyethersulfone-based resin is too large, the dope will gel and become uneven. There is a case.

  (A) The polyethersulfone-based resin may be 1 to 50 parts by weight, preferably 3 to 40 parts by weight, and more preferably about 5 to 30 parts by weight with respect to 100 parts by weight of the (b) hydrophilic polymer. Good.

  (A) The polyether sulfone resin may be 10 to 80 parts by weight, preferably 15 to 75 parts by weight, and more preferably about 20 to 70 parts by weight with respect to 100 parts by weight of the (c) solvent. When the ratio of the (a) polyethersulfone resin to the (c) solvent is too small, the mechanical strength is inferior and it is difficult to form pores. On the other hand, when the ratio is too large, the resin may be gelled.

  The ratio of (b) hydrophilic polymer to (c) solvent is the former / the latter (weight ratio) = 1.5 / 1 to 2.7 / 1, preferably 1.6 / 1 to 2.7. / 1 (e.g. 1.6 / 1 to 2.5 / 1), more preferably 1.7 / 1 to 2.7 / 1 (e.g. 1.7 / 1 to 2.6 / 1), in particular It is about 1.8 / 1 to 2.6 / 1 (for example, 1.9 / 1 to 2.5 / 1). When the ratio of the hydrophilic polymer (b) to the solvent (c) is too small, a sufficient porosity (particularly, the porosity of the membrane surface) cannot be obtained, and an asymmetric membrane tends to be obtained. On the other hand, if the ratio of (b) hydrophilic polymer to (c) solvent is too large, (a) the polyethersulfone-based resin flows out without being sufficiently dissolved, or a large amount of (b) hydrophilic polymer causes (A) Since the polyethersulfone-based resin is compressed, the resulting film may be inferior in mechanical strength and may have a small film thickness.

  The ratio of (b) hydrophilic polymer to (c) solvent is 1.7 / 1 to 2.7 / 1, preferably 1.75 / 1 to 2.65 / 1, and more preferably 1.8. / 1 to 2.6 / 1, especially a porous body excellent in adhesiveness (or adhesion) with a substrate when a laminate described later is formed using a dope that is about 1.9 / 1 to 2.5 / 1. Useful for producing a membrane. In such a porous membrane, even when the substrate and the laminate are formed, the porous membrane (or the substrate) can be maintained in water for a long time without peeling off in the water.

  The dope may contain an additive as necessary. Additives are not particularly limited, and conventional additives such as stabilizers (thermal stabilizers, antioxidants, ultraviolet absorbers, etc.), antiblocking agents, antifogging agents, antistatic agents, colorants (dyes) , Pigments, etc.), coupling agents, flame retardants, lubricants, mold release agents, fragrances, plasticizers, biocides (bactericides, bacteriostatic agents, antifungal agents, antiseptics, insecticides, etc.), viscosity modifiers, It may be a dispersant or the like. An additive can be used individually or in combination of 2 or more types. These additives may be contained in the resin ((a) polyethersulfone resin) that forms the porous membrane, or may be contained in the pores (or pores) of the porous membrane. Good.

  The porous membrane may contain a filler. This filler may be composed of a filler mixed or dispersed in the resin forming the porous film, impregnated (or retained) in the pores (or pores) of the porous film, and the porous You may comprise with the filler (for example, the below-mentioned filler etc.) hold | maintained at a film | membrane. The filler may be, for example, a powdery filler such as silica, mica, talc, calcium carbonate; a fibrous filler such as glass fiber, carbon fiber, and pulp.

Further, the dope is a poor solvent for the (a) polyethersulfone resin, and (b) the hydrophilic polymer and ( c) A liquid component (or a coagulation accelerator) which is a good solvent for the solvent may be contained. From the viewpoint of wide availability and removability after film formation, examples of the liquid component include water, water-soluble organic solvents [for example, alcohols (for example, methanol, ethanol, 1-propanol, isopropanol, 1-butanol). C _1-7 alkanols such as hexanol; C _2-6 alkanediols such as ethylene glycol, propylene glycol, butylene glycol (or 1,4-butanediol), cellosolves (methyl cellosolve, ethyl cellosolve, etc.) C _1-4 alkyl cellosolves), cellosolve acetates (C _1-4 alkyl cellosolve acetates such as ethyl cellosolve acetate), carbitols (C _1-4 alkyl carbitols such as methyl carbitol, ethyl carbitol, etc.) Etc)] etc. Preferred. A liquid component can be used individually or in combination of 2 or more types. Of these liquid components, water is particularly preferable from the viewpoint of production cost.

(Dope)
The dope (or film forming stock solution) may be prepared by mixing and dissolving at least three components (the (a) polyethersulfone resin, (b) hydrophilic polymer and (c) solvent). In order to completely dissolve the components in a short time, it is preferable to prepare by mixing and dissolving the three components stepwise (or individually). That is, the dope is prepared by dissolving one component of (a) a polyethersulfone-based resin and (b) a hydrophilic polymer in the solvent (c) and then further dissolving the other component. May be. In addition, when each component is dissolved in the solvent (c), the whole amount may be dissolved at once (or once), or may be dissolved in batches (or divided into a plurality of times). Specifically, for example, after mixing and dissolving (b) a hydrophilic polymer in an amount of half the amount added to the solvent (c), (a) the entire amount of the polyethersulfone resin is batched (or batched). And the remaining (b) hydrophilic polymer may be mixed and dissolved.

  The viscosity of the dope can be measured using a B-type viscometer. For example, (a) a polyethersulfone-based resin, (b) a hydrophilic polymer, and (c) a solvent are (a) a polyethersulfone-based resin / The viscosity of the dope with (b) hydrophilic polymer / (c) solvent (weight ratio) = 13/63/24 is, for example, 100 to 10000 cps (0.1 when measured under conditions of 6 rpm and 23 ° C. 10 Pa · s), preferably 500 to 9000 cps (0.5 to 9 Pa · s), more preferably about 1000 to 8000 cps (1 to 8 Pa · s). When the viscosity is less than 100 cps (0.1 Pa · s), the dope easily flows and the thickness of the formed porous film is reduced. On the other hand, when the viscosity exceeds 10,000 cps (10 Pa · s), it is difficult to obtain a uniform dope.

  When the dope is formed, humidified and solidified, a porous film can be produced. In the conventional method, it is manufactured by the following method. First, a uniformly prepared dope (a dope composed of a hydrophobic resin, a hydrophilic polymer, and a solvent) is formed into various forms (for example, a hollow fiber film form, a film form, etc.). In the deposited dope, as the solvent evaporates, the hydrophobic resin and the hydrophilic polymer undergo phase separation (coacervation), and the hydrophobic resin gels (or coagulates and leaches), The hydrophobic resin aggregates into fine particles to form an aggregate. The hydrophilic polymer is held in the pores (or pores) formed in the aggregate. Next, the aggregate is brought into contact with a solvent [coagulation solvent (for example, water)] that is a poor solvent for the hydrophobic resin and is a good solvent for the hydrophilic polymer and the solvent. When completely solidified and the hydrophilic polymer and solvent are washed, removed and dried, a porous membrane composed of the hydrophobic resin can be obtained. However, on the film surface, the evaporation of the solvent proceeds faster than the inside of the film, and the gelation (or solidification) of the hydrophobic resin also occurs earlier, so that it is denser than the porous layer formed inside the film. A layer (dense layer) is formed, and an asymmetric membrane in which the porosity changes in the thickness direction is formed.

  Therefore, in the present invention, as described later, in the manufacturing method, (1) the ratio of (b) the hydrophilic polymer to the solvent is set to a specific ratio, and (2) the film is specified after the dope is formed. By humidifying under the conditions, a porous film having a high porosity and a uniform porosity in the thickness direction can be obtained.

  The first feature of the production method of the present invention is that (1) a dope having a specific ratio of (b) hydrophilic polymer to (c) the solvent is used to obtain a porous film having a high porosity. It is in. That is, (b) when the content of the hydrophilic polymer is high, a large number of pores formed in the aggregate can be secured, and (c) the pores can be prevented from shrinking even when the solvent evaporates. The porosity can be kept high. Such an action works substantially equally on the film surface and inside the film, and is useful for forming a porous film having a uniform porosity in the thickness direction.

  The second feature of the production method of the present invention is that (2) after forming a dope film, the film is humidified under specific conditions described later to increase the uniformity of the porosity in the thickness direction, and the productivity of the porous film It is to raise. That is, as described above, on the surface of the film, (c) the reduction of the pores accompanying the evaporation of the solvent proceeds faster than in the inside of the film, and there is a tendency to form a dense layer. However, when the formed dope is humidified, water vapor in the atmosphere is mainly adsorbed to the (b) hydrophilic polymer on the film surface, and the reduction of pores on the film surface is suppressed, so that a dense layer is formed. In addition, a porous film having a uniform porosity in the thickness direction can be obtained. Further, the action of the water vapor can promote the phase separation and coagulation of the hydrophobic resin, thereby enhancing the productivity of the membrane. Note that the end point of the phase separation may be determined using the fact that the transparent (or light yellow transparent) dope becomes cloudy (or changes to white) as the phase separation proceeds.

In the second feature, it is preferable to supply a large amount of water vapor per unit time and humidify. The water vapor supplied per unit time / unit area with respect to the dope is 1 to 1000 g / m ² · second, preferably 3 to 500 g / m ² · second, more preferably 5 to 300 g / m ² · second, particularly It may be about 10 to 100 g / m ² · second (for example, 10 to 50 g / m ² · second). Further, the water vapor supplied per unit time / unit area to the dope is 1 to 500 g / m ² · second, preferably ^{2 to} 200 g / m ² · second, more preferably 3 to 100 g / m ² · second. In particular, it may be about 5 to 80 g / m ² · second (for example, 10 to 70 g / m ² · second). The amount (or ratio) of water vapor supplied per unit time / unit area can be calculated by the following method.

(1) The dope is cast (or coated) to form a film, and the weight of the film (W1 (g)) is immediately measured. (2) The film is placed in a chamber adjusted to a predetermined temperature and humidity. Then, after humidifying for a certain time (T (seconds)), the membrane is taken out of the chamber and the weight of the membrane (W2 (g)) is measured. (3) The measured weight, humidification time and membrane area S (m ²⁾ ) To calculate the amount of water vapor (W (g / m ² · sec)) supplied per unit time / unit area using the following formula (1):
W (g / m ² · sec) = (W2−W1) / (S · T) (1)
In order to supply a large amount of water vapor per unit time, it is effective to humidify at a relatively high humidity. Specifically, the relative humidity (in the atmosphere) of about 80 to 100%, preferably 82 to 99.5%, more preferably 85 to 99%, particularly 86 to 98.5% (for example, 87 to 98%). Relative humidity) may be used for humidification.

  As described above, in the present invention, a large amount of water vapor can be supplied per unit time, and (a) the polyethersulfone-based resin can be instantly solidified. Therefore, the humidification time is 0.1 to 300 seconds, preferably It may be 1 to 180 seconds, more preferably 3 to 60 seconds, particularly about 5 to 30 seconds. Moreover, even if the humidification time is a very short time of about 1 to 10 seconds (for example, 1 to 7 seconds), a homogeneous porous film can be obtained efficiently, which is industrially advantageous. The humidification time may be appropriately selected according to the desired porosity and atmospheric conditions. Further, the humidification temperature may be 10 to 90 ° C., preferably 20 to 80 ° C., more preferably about 30 to 70 ° C., for example, about 20 to 60 ° C. The formed dope may be humidified in any environment as long as water is applied. For example, the dope may be humidified in an open space (or an open system). For example, it is preferable to humidify in a closed space (or closed system) such as a humidifying tank.

  In the humidified dope, in order to completely solidify the hydrophobic resin (the (a) polyethersulfone resin), the dope may be brought into contact with at least the coagulation solvent. The method for bringing the dope into contact with the coagulation solvent is not particularly limited, and may be a method of injecting the coagulation solvent onto the dope, but in order to coagulate efficiently, the dope is immersed in the coagulation solvent. Is preferred. The immersion time is not particularly limited, and may be, for example, 1 second to 10 minutes, preferably 10 seconds to 7 minutes, more preferably 30 seconds to 5 minutes, and particularly about 50 seconds to 3 minutes. The temperature of the coagulation solvent to be immersed may be, for example, about 5 to 80 ° C., preferably 10 to 60 ° C., and more preferably about 15 to 30 ° C.

  As the coagulation solvent, a solvent that is a poor solvent for the (a) polyethersulfone resin and a good solvent for the (b) hydrophilic polymer and (c) the solvent is preferably used. Exemplary coagulation promoters can be used. The coagulation solvent may be used alone or in combination of two or more. The coagulation solvent is not particularly limited as long as it is liquid at the temperature at which the dope is immersed, but water is usually used in many cases from the viewpoint of production cost.

  In the present invention, as described above, since the phase separation and the coagulation action of the hydrophobic resin are promoted, a porous material that coagulates from one surface of the inner wall surface and the outer wall surface to the other surface, like a hollow fiber membrane. Even if it is a membrane, a homogeneous film can be formed by the coagulation promoting action.

  In the present invention, the method for forming a dope is not particularly limited. For example, the dope is cast on a substrate to form a film, and the formed dope is made porous by the above method to form a porous film. Then, the porous film may be peeled (or separated) from the base material to form a porous film (or a porous film alone). In addition, for example, a dope is applied to a substrate to form a film, the formed dope is made porous, and the formed porous film is not peeled (or separated) from the substrate, and the substrate and the substrate are formed. You may form the laminated body comprised with the porous film laminated | stacked on the material. The porous film may be laminated on at least one surface (one surface or both surfaces) of the base material (or layer).

  The base material can be appropriately selected depending on the application from the viewpoints of heat resistance, mechanical strength, electrical properties, etc., for example, an inorganic base material [for example, metals (for example, titanium, aluminum, copper, silver, iron, etc. , Nickel, titanium, tin, zirconium and other metals or alloys thereof, stainless steel, etc.); ceramics (for example, oxides, nitrides, carbides, borides, etc. of the above metals); carbons such as carbon fibers, etc. ] May be configured. Moreover, the said base material may be comprised with organic type base materials [For example, resin (for example, resin etc. which are mentioned later)]. These substrates can be used alone or in combination of two or more. In the production method of the present invention, since phase separation occurs quickly, it is possible to cope with substrates having various surface tensions, and thus a wide variety of substrates can be used.

  The form of the substrate is not particularly limited, and may be, for example, a sheet shape, a film shape, a plate shape (cuboid, cube, etc.), a curved surface shape, a spherical shape, and the like. In addition, the said base material may have a hole (or through-hole), for example, mesh shape (or mesh shape), such as a mesh cloth and a wire net; punching shape (or polka dot shape), such as a punching film and a punching metal Expanded shape (or diamond shape) such as expanded metal; Etched shape; Grid shape (or lattice shape) such as woven fabric and nonwoven fabric may be used. A base material having such a hole (or through-hole) may be used for, for example, a separation membrane such as a filtration membrane to enhance the separation ability.

  From the viewpoints of adhesiveness (or adhesion) with the porous membrane, mechanical strength, etc., the base material is preferably in the form of a sheet (or film), and in particular, is non-porous having no pores. The sheet form (or film form) is preferred. In addition, the said base material may be formed with the single layer, and may be formed with the several layer by which the same or different base material was laminated | stacked. Note that the substrate formed of the plurality of layers may be formed by laminating a single layer substrate using an adhesive. In addition, the base material formed of the plurality of layers includes a base material obtained by subjecting a single layer base material to a coating process, a vapor deposition process, a sputtering process, and the like.

  Preferred methods for producing the porous membrane include the following methods. For example, the dope is cast on a base material that can be peeled off from the dope (or porous film) (for example, a base material made of polyester resin such as polyethylene terephthalate, metals, or the like) and formed into a film. And after making dope porous by the said method, a porous membrane may be isolate | separated (or peeled) from a base material, and a porous membrane may be manufactured.

  On the other hand, the dope is applied to a substrate having high adhesion (or adhesion) with the dope (or porous film) to form a film, and the dope is made porous by the above method to form a porous film. A laminate composed of the base material and the porous film laminated on the base material may be produced without separating (or peeling) the porous film from the base material. The substrate is made of a polysulfone resin such as a polysulfone resin, a polyethersulfone resin, or a polyarylsulfone resin from the viewpoint of adhesion (or adhesion) to the porous membrane and interlayer strength. Is preferred. In particular, the substrate is preferably composed of a polyethersulfone resin.

  More specifically, the dope is applied to at least one surface of a base material (for example, a sheet-like base material made of polyethersulfone resin) to form a film, and the resulting laminate is (B) hydrophilic polymer and (c) solvent are removed, and (a) a laminate of a porous membrane composed of a polyethersulfone-based resin and the base material It may be manufactured. The laminate may be produced by using a conventional method, for example, a method of laminating a substrate and a porous film using an adhesive, but from the viewpoint of simplicity, as described above. It is preferable to manufacture by using an application method (or coating method).

[Porous membrane]
The porous film formed by the above method is an aggregate (sometimes referred to as an aggregate of fine particles) formed by aggregation of the (a) polyethersulfone resin into fine particles. The structure can be observed with a scanning electron microscope (SEM). FIG. 1 is a schematic cross-sectional schematic diagram showing the particle structure of the porous layer in the process of phase separation accompanying the evaporation of the solvent (c). As shown in FIG. 1, the (a) polyethersulfone resin may be aggregated randomly in the form of fine particles.

  In the aggregate, it is preferable that the average particle diameter of the part observed in the form of particles is uniform (or almost uniform), and it is particularly preferable that the average particle diameter is uniform (or almost uniform) in the thickness direction. In addition, as shown in FIG. 2, the average particle diameter is based on an electron micrograph of the surface of the porous membrane (or the region or layer to be measured) when the resin fine particles are assumed to be a perfect circle (resin The virtual circle of the particle 1) means the diameter (or average diameter) calculated from the average area of a plurality of resin fine particles arbitrarily selected. The average particle diameter and the degree of uniformity of the average particle diameter in the thickness direction can be measured using a scanning electron microscope (SEM). For example, as shown in FIG. 3, the porous film is formed in the thickness direction in the cross section, in the vicinity of the surface (or the surface layer 5), the vicinity of the back surface (or the back surface layer 7), the region (or the intermediate layer 6) (or The average particle diameter (dA) of the part observed in the particle form on the surface 3 and the average particle diameter (dB) of the part observed in the particle form on the surface layer 5 The average particle diameter (dC) of the part observed in the particulate form in the intermediate layer 6, the average particle diameter (dD) of the part observed in the particulate form in the back layer 7, and the part observed in the particulate form on the back face 4 The average particle diameter (dE) is measured. The average particle diameter may be, for example, about 0.01 to 1 μm, preferably 0.05 to 0.8 μm, and more preferably about 0.1 to 0.5 μm. When the average particle diameter is too small, the particles are likely to be densely packed and the porosity is lowered. On the other hand, when the average particle diameter is too large, the cohesive force between the particles is small, and the mechanical strength of the film is lowered. Moreover, the ratio of the maximum value and the minimum value of the measured dA to dE is, for example, the former / the latter = 1/1 to 5/1, preferably 1.02 / 1 to 3/1, and more preferably 1.03 /. It is about 1 to 2/1 (particularly, 1.05 / 1 to 1.5 / 1). That is, in the aggregate, the average particle diameter of the part observed in the form of particles has the same average particle diameter in the thickness direction.

  On the other hand, the average pore diameter of the pores formed in the aggregate is also preferably uniform (or substantially uniform), and particularly preferably uniform (or substantially uniform) in the thickness direction. In addition, as shown in FIG. 2, the average pore diameter is based on an electron micrograph of the surface of the porous membrane (or the region or layer to be measured) when the pore is assumed to be a perfect circle (hole) Virtual circle 2) means a diameter (or average diameter) calculated from an average area of a plurality of arbitrarily selected holes. The average pore diameter and the degree of uniformity of the average pore diameter in the thickness direction can also be measured using a scanning electron microscope (SEM). For example, similar to the measurement of the average particle diameter, the average pore diameter (φA) of the pores observed on the surface 3, the average pore diameter (φB) of the pores observed on the surface layer 5, and the intermediate layer 6 are observed. The average hole diameter (φC) of the holes, the average hole diameter (φD) of the holes observed in the back surface layer 7 and the average hole diameter (φE) of the holes observed in the back surface 4 are measured. The average pore diameter may be, for example, about 0.1 to 20 μm, preferably about 0.2 to 10 μm, and more preferably about 0.3 to 5 μm. In addition, the ratio of the maximum value and the minimum value of the measured φA to φE is, for example, the former / the latter = 1/1 to 10/1, preferably 1.03 / 1 to 5/1, and more preferably 1.05 /. It is about 1 to 3/1 (particularly 1.1 / 1 to 2/1). That is, the average hole diameter of the holes has the same average hole diameter in the thickness direction.

The ratio between the average pore diameter and the average particle diameter is the former / the latter = 1/1 to 20/1, preferably 1.1 / 1 to 15/1, more preferably about 1.5 / 1 to 10/1. It may be. When the ratio is less than 1/1, the resulting film has a small porosity and is dense, and is unsuitable for applications involving a filler to be described later. On the other hand, when the said ratio is larger than 20/1, the film | membrane obtained is inferior to mechanical strength. The porosity of the porous film may be about 40 to 90%, preferably about 50 to 85%, and more preferably about 60 to 80% (for example, 65 to 80%). The porosity is expressed by the following formula (2)
Porosity (%) = 100−100 × W / (D · V) (2)
(Wherein, V is the volume of the porous membrane, W is the weight of the porous membrane, D is the density of the porous membrane (or (a) the polyethersulfone resin), and D (g / cm ³ ) = 1. .37). The standard deviation of the porosity in the thickness direction is 0.1 to 10%, preferably 0.15 to 8%, more preferably 0.2 to 7%, particularly 0.25 to 6% (for example, About 0.3 to 5%). Furthermore, when the porosity is measured for each of the three regions (surface layer 5, intermediate layer 6 and back layer 7), the ratio between the maximum value and the minimum value of the porosity is the former / the latter = 1 / 1 to 5/1, preferably about 1.01 / 1 to 3/1, more preferably about 1.03 / 1 to 1.5 / 1 (especially 1.05 / 1 to 1.2 / 1) Also good.

Since the porous membrane of the present invention has a high porosity and the porosity is uniform (or almost uniform) in the thickness direction, it is excellent in the permeability (air permeability, water permeability, etc.) of various fluids. For example, the Gurley air permeability according to JIS P 8117 is 0.2 to 30 seconds / 100 ml, preferably 0.5 to 25 seconds / 100 ml, more preferably about 1 to 20 seconds / 100 ml. When the Gurley air permeability is larger than the above range, the practical permeability is insufficient and the filler cannot be sufficiently impregnated or retained. On the other hand, if the Gurley air permeability is smaller than the above range, the mechanical strength is inferior. The pure water permeation rate is 10,000 to 16000 L / (m ² · h · MPa), preferably 20000 to 150,000 L / (m ² · h · MPa), more preferably 30000 to 130000 L / (m ² · h · MPa). )

  The film thickness of the porous membrane can be selected from about 1 to 300 μm, preferably 5 to 250 μm, and more preferably about 10 to 200 μm. In addition, when using the said porous film as a laminated body with a base material, a film thickness is 1-200 micrometers from a viewpoint of adhesiveness (or adhesiveness) with a base material, Preferably it is 10-150 micrometers, Furthermore, Preferably, it may be about 20 to 100 μm. When the film thickness is less than 1 μm, the filling property (or holding property, accommodation property, accommodation property) and mechanical strength of the filler are inferior, and the uniformity of the film thickness and the adhesion to the substrate are inferior. On the other hand, if the film thickness exceeds 200 μm, it is difficult to adjust the porosity and the homogeneity may be lowered. In addition, when a film thickness of 200 μm or more is required, a plurality of the porous films having a film thickness of 200 μm or less may be laminated.

Since the porous membrane of the present invention has a high porosity and the porosity is uniform (or almost uniform) in the thickness direction, a functional membrane containing a filler in the pores (or pores) ( Or a composite membrane). Various fillers can be used as the filler, and the filler may be solid (or solid), liquid (or liquid, molten), or gas. When a solid (or solid material) is used as the filler, the shape that can be used is not particularly limited, and the shape is, for example, a zero-dimensional shape (granular, pellet-like, etc.), a one-dimensional shape (strand-like, rod-like). Etc.), a two-dimensional shape (plate, sheet, film, etc.), a three-dimensional shape (tubular, block, etc.), etc. When a solid (or solid material) is used as the filler, the filler may be contained in a dissolved or dispersed state in a solvent or in a molten state from the viewpoint of easy filling. Further, the filler may be an electrolyte (or ionic substance) or a non-electrolyte (or nonionic substance). For example, when an electrolyte such as a monomer or polymer having an ion exchange group (for example, —SO ₃ ^— derived from a sulfonic acid group) is used as the packing, ion exchange is performed on the porous membrane (or functional membrane). Ability can be granted. A filler can be used individually or in combination of 2 or more types. When a plurality of fillers are used in combination, the filler may be selectively included by adjusting the properties and / or shape of the filler used, the porosity of the porous membrane, and the like. it can.

  Since the porous membrane of the present invention has a high porosity, it can contain viscous or solid resins, and the resins are stably held (or fixed) inside the membrane. The resins may be conventional resins such as thermoplastic resins {for example, olefin resins, styrene resins, vinyl resins, thermoplastic acrylic resins, polyester resins [for example, polyalkylene arylate resins (polyethylene terephthalate; PET, polybutylene terephthalate; PBT, polyethylene naphthalate; PEN, etc.), etc.], polycarbonate resins, fluorine resins, polyamides Resin (for example, aliphatic polyamide, alicyclic polyamide, partially or fully aromatic polyamide), polysulfone resin (polysulfone resin; polyethersulfone resin; polyarylsulfone such as polyphenylsulfone resin) Resin), polyether ether ketone resin, polyphenylene sulfide resin, etc.], thermosetting (or photo) curable resin [for example, phenol resin, urea resin, melamine resin, epoxy resin, unsaturated polyester resin, urethane resin, Heat (or light) curable acrylic resin (eg, epoxy (meth) acrylate, polyurethane (meth) acrylate, etc.), silicone resin, polyimide resin (eg, polyimide resin, polyetherimide resin, polyesterimide resin) , Polyamideimide resins, etc.), polybenzoxazole resins, polybenzimidazole resins, polybenzothiazole resins, etc.], cellulose resins, and the like. These resins may be used singly or as a blend of two or more. Further, the resin copolymer (graft polymer, block copolymer, random copolymer, etc.), the resin skeleton (polymer) A polymer containing a main chain or a side chain may be used. Resins can be used individually or in combination of 2 or more types. Of these resins, the heat (or light) curable resin is preferable, and among them, epoxy resin, unsaturated polyester resin, heat (or light) curable acrylic resin (for example, epoxy (meth) acrylate, polyurethane (meta) ) Etc.), silicone resins and the like are preferably used.

  The method of including the filler in the porous membrane includes, for example, (1) a method of applying (or adding) the filler to the surface of the porous membrane and impregnating the porous membrane, and (2) the filler (the filler). And a method of immersing the porous membrane in a solution or a melt containing the same), (3) a method of transferring the filler formed into a film shape to the porous membrane, and the like. In the method (1), a conventional coating machine (for example, a die head coater, a bar coater, a comma coater, a gravure coater, etc.) can be used as the coating member for coating the filler. In the method (3), heat or pressure may be applied from the viewpoint of transfer efficiency. Furthermore, as a transfer member for transferring the film-like filler, a commonly used roll, press plate, or the like may be used. The method for impregnating the porous membrane with the filler may be used alone or in combination of two or more.

  Of these methods, the filler can be used efficiently, is stably held, and is excellent in economic efficiency. Therefore, the method (1) is used to include the filler composed of the resins. Is preferred. The resin is applied (or added) to the surface of the porous film to be included (or filled). For example, the resin is dissolved in a solvent and applied (or added) in a solution state to be filled. A method in which the resins are dispersed in water and applied (or added) and filled in an emulsion state, and a method in which the resins are melted and applied (or added) in a molten (or softened) state and filled. It may be.

  The heat (or light) curable resin is used as the filler, and the resin (non-curable resin) is included in the absence of a solvent and then cured with heat (or light). Dissolution of the porous membrane, melting of the porous membrane due to overheating, and the like can be suppressed. Further, from the viewpoint of operability, a polymerizable monomer may be used as the filler and polymerized inside the porous membrane.

  As long as the properties of the present invention are not impaired, the filler may be contained in a part of the pores of the porous membrane or may overflow from the porous membrane, but the properties can be sufficiently exhibited. And from the point which is excellent in economical efficiency, it is preferable that the said filling material is filled and filled with the porous membrane (or the inside of the void | hole). In addition, you may scrape off the excess filler overflowing from a porous membrane using a general purpose member (for example, squeeze roll etc.).

  Since the porous membrane of the present invention is a homogeneous membrane having a uniform porosity in the thickness direction, it is useful as a support for containing various fillers. For example, when the porous membrane is used as a support and a resin is included as a filler, the mechanical properties (eg, tensile modulus, tensile strength, tensile elongation, etc.) of the porous membrane and / or resin are improved. be able to. Specifically, when the porous film is filled with the resin, the mechanical properties are, for example, 5 times or more (for example, about 6 to 100 times), preferably 7 times that of the case where the resin is used alone. It can be improved to the above (for example, about 8 to 50 times), more preferably 10 times or more (about 12 to 30 times). Specifically, the tensile elastic modulus of the functional membrane obtained by filling the porous membrane (thickness of about 40 to 45 μm) of the present invention with a silicone resin is 15 to 50 MPa, preferably 18 to 45 MPa, more preferably 20 About 40 MPa may be sufficient. The tensile modulus of the silicone resin alone is about 0.5 to 5 MPa.

The porous membrane of the present invention may be filled with an electrolyte polymerizable monomer as a filler and polymerized to form an electrolyte membrane. Specifically, the electrolyte membrane can be formed by filling or impregnating the porous membrane with an electrolyte polymerizable monomer and polymerizing the inside of the membrane. As the polymerizable monomer for the electrolyte, for example, a monomer described in JP-A-2002-83612 can be used. For example, a monomer having an ion exchange group (for example, —SO ₃ ^— derived from a sulfonic acid group) (for example, , Sulfone-based monomers, etc.) are preferably used. Such an electrolyte membrane is useful as a member for a fuel cell or the like.

If necessary, the pores may be eliminated by dissolving and homogenizing the porous membrane (or porous layer) using an eluent (or dissolution solvent, elution solvent). The dissolving solvent can be appropriately selected and is not particularly limited as long as the porous film can be dissolved, but usually contains a good solvent for the porous film in many cases. Such an eluent (or a good solvent for the porous membrane) includes, for example, the above-mentioned solvent (c), as well as cyclo C _3-10 alkanols such as cyclopropanol and cyclohexanol; dimethyl ether, diethyl Chain ethers such as ethers; Ketones such as methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclopentanone and cyclohexanone; Esters (chain esters) such as methyl acetate, ethyl acetate, methyl lactate and ethyl lactate Hydrocarbons (for example, aliphatic hydrocarbons such as pentane and hexane, alicyclic hydrocarbons such as cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons, phenols, etc.) It may be. The eluent is excellent in operability and suppresses the occurrence of unevenness (surface unevenness). Therefore, a low-volatile solvent (for example, a solvent having a boiling point of 150 ° C. or higher, for example, a sulfur-containing solvent (for example, dimethylsulfoxide) Sulfoxides), ethyl lactate, esters such as γ-butyrolactone (GBL), hydrocarbons, etc.) are preferably used. The eluent may be a single solvent or a mixed solvent of two or more.

Further, the eluent may be a mixed solvent further containing a poor solvent for the porous film (for example, the exemplified coagulation accelerator) as long as the porous film can be dissolved. The poor solvent may be a low-volatile solvent (for example, C _2-6 alkanediols such as ethylene glycol, cellosolves, cellosolve acetates, carbitols, etc.). However, in order to prevent sudden (or sudden) volatilization of the eluent, the poor solvent is a highly volatile solvent (for example, a solvent having a boiling point of 100 ° C. or less, such as water, methanol, ethanol, isopropanol, etc. C _1-4 alkanols and the like. As a combination of the eluent (or good solvent) and the poor solvent, for example, a combination of dimethyl sulfoxide (good solvent) and isopropanol (poor solvent), γ-butyrolactone (good solvent) and water (poor solvent) Examples include combinations. The ratio of the eluent (or good solvent for the porous membrane) and the poor solvent is the former / the latter (weight ratio) = 20/80 to 80/20, preferably 30/70 to 70/30, more preferably May be about 40/60 to 60/40.

  In addition, as described above, the eluent (or dissolving solvent) is not limited to the good solvent for the porous film, the mixed solvent of the good solvent for the porous film and the poor solvent for the porous film, for example, Even a mixed solvent obtained by combining a plurality of poor solvents of the exemplified porous membrane can be used as long as the porous membrane can be dissolved.

  Moreover, since the porous film of the present invention is a homogeneous film having a uniform porosity in the thickness direction, it is particularly useful for printing applications. In this specification, “printing” is not limited to the purpose of applying ink to the printing plate surface and transferring it to paper or the like to make a copy, but transferring ink having various functions to make the porous film highly functional. It is used in the meaning that includes.

  Conventionally, films composed of various resins (for example, polyethylene terephthalate (PET) resin, polyimide (PI) resin, etc.) have been used as printed materials because of their excellent heat resistance and mechanical properties. Yes. However, when a film is used as a substrate, printing ink is diffused on the film surface, so that it is difficult to print with good print reproducibility (or pattern accuracy). Attempts have been made to use a porous printing medium (porous film) in order to increase the solvent absorbability of printing ink and improve printing reproducibility (or pattern accuracy). An asymmetric film having a dense layer on the film surface, and ink or its solvent absorbability is not sufficient. However, since the porous film of the present invention is a homogeneous film made of a polyethersulfone resin having excellent heat resistance and mechanical properties and having a uniform porosity in the thickness direction, printing ink (or When the paste) comes into contact (or adheres), the ink or its solvent is immediately absorbed (or impregnated) into the film, so that the ink is fixed (or held) on the film surface. Therefore, in the porous film of the present invention, excellent pattern accuracy can be shown without ink diffusing on the film surface. As an index of the pattern accuracy, for example, in plate printing, printing was performed corresponding to the width L1 of the image line portion (or ink oleophilic (lipophilic) portion, ink adhering portion, etc.) of the plate and the image line portion. The ratio (L2 / L1) to the line width L2 is about 0.8 to 1.2, preferably about 0.85 to 1.15, and more preferably about 0.9 to 1.1. The width L1 of the image line portion may be, for example, about 5 to 1000 μm, preferably about 10 to 500 μm, and more preferably about 15 to 100 μm. The porous film of the present invention can be used for various printing methods, for example, inkjet printing, intaglio printing (gravure printing, etc.), relief printing, planographic printing (offset printing), stencil printing (screen printing, etc.), It is suitably used for stencil printing such as printing in which paste is extruded with a screen mesh (or metal mask), screen printing, and the like.

The printing ink (or paste) is not particularly limited, and for example, ink (or paste) containing a functional component, a binder resin, and a solvent is used. The functional component can be appropriately selected according to the purpose. For example, a dye or pigment [oil-soluble dye, disperse dye, vat dye, sulfur dye, azoic dye, inorganic pigment, organic pigment, fluorescent pigment or dye, phosphorescent pigment, etc. ] And the like. The functional component includes, for example, an inorganic component {for example, a metal component (for example, the above exemplified metals); a ceramic component (for example, the above exemplified ceramics); glass; a carbon component; an inorganic electroluminescence (for example) EL) material [an EL material composed of a base material (for example, a periodic table group IIB-VIB compound semiconductor such as ZnS or CdS, a periodic table group IIA-VIB compound semiconductor such as CaS or SrS) and a luminescent center. (For example, white light-emitting materials such as SrS: Ce / ZnS: Mn, red light-emitting materials such as ZnS and Mn / CdSSe, green light-emitting materials such as ZnS: TbOF and ZnS: Tb, and blue-green light-emitting materials such as SrS: Ce, _{(SrS: Ce / ZnS) n} , Ca 2 Ca 2 S 4: Ce, Sr 2 Ga 2 S 4: such as blue light emitting materials such as Ce)], etc. Organic components {e.g., (such as a conductive polymer) resins, organic semiconductor materials (pentacenes, thiophenes, etc.)} may be. You may use a functional component individually or in combination of 2 or more types. The form of the functional component is not particularly limited as long as it does not impair printability (or pattern accuracy), and may be, for example, granular or scale-like (or flaky or fibrous). The functional component may be hollow.

  The binder resin may be a general-purpose resin such as the exemplified resins. Binder resins can be used alone or in combination of two or more.

  The solvent can be appropriately selected according to the type of functional component, binder resin, etc. used, for example, water, alcohols, ethers, ketones, carboxylic acids (or anhydrides thereof), esters, nitrogen-containing solvents. (For example, amides, nitriles, amines and the like), sulfur-containing solvents, hydrocarbons (including halogenated hydrocarbons and phenols), and the like may be used. In addition, the solvent as described in Unexamined-Japanese-Patent No. 2004-319281, Unexamined-Japanese-Patent No. 2004-111057, Unexamined-Japanese-Patent No. 2006-059669, Unexamined-Japanese-Patent No. 2004-143325 etc. can also be used for a solvent, for example. The solvent may be a single solvent or a mixed solvent of two or more. The ratio (weight ratio) between the total of the functional components and binder resin and the solvent may be about the former / the latter = 1/99 to 80/20, preferably 5/95 to 70/30, Preferably, it may be about 10/90 to 65/35.

  In order to absorb (or impregnate) the solvent contained in the printing ink (or paste) mainly into the porous film, the properties of the printing ink (or paste) may be adjusted. For example, when the viscosity of the printing ink (or paste) is measured under conditions of 10 rpm and 23 ° C. using a viscometer (manufactured by Toki Sangyo Co., Ltd., “VISCOMETER model BM”), for example, 0. It may be about 05 to 1 Pa · s, preferably 0.1 to 0.9 Pa · s, and more preferably about 0.15 to 0.8 Pa · s. The viscosity of the printing ink (or paste) can be adjusted according to the functional component, the type and / or concentration of the binder resin, the type of solvent, and the like. In addition, the printing ink or paste [or the solvent (particularly, the solvent having the largest content ratio among all solvents)], from the viewpoint of pattern accuracy, when 1 μL of droplets are dropped on the surface of the porous film, The contact angle (contact angle after 300 μs after dropping) is 60 ° or less (for example, about 0 to 60 °), preferably 50 ° or less (for example, about 1 to 50 °), and more preferably 40 ° or less (for example, , About 2 to 40 °) is preferable. Further, the size (droplet radius) of the droplet after 300 μsec after dropping is, for example, 1600 μm or less (for example, about 10 to 1550 μm), preferably 1500 μm or less (for example, about 20 to 1450 μm), more preferably It may be 1400 μm or less (for example, about 30 to 1300 μm).

  Use of such a printing ink (or paste) is useful because various electronic materials (for example, wiring, inductor, light emitter, resistor, capacitor, semiconductor, etc.) can be easily and efficiently manufactured. For example, when printing (plate printing) is performed using conductive ink (or conductive paste) as the printing ink (or paste), it can be used as a printed wiring board on which conductive wiring (or circuit) is formed. As the conductive ink (or conductive paste), a conventional conductive ink (or conductive paste) can be used. Specifically, the conductive ink includes gold ink, silver ink, silver nanometal ink, copper ink, carbon ink, silver- Carbon ink is included. The conductor paste includes gold conductor paste, silver conductor paste, copper conductor paste, palladium conductor paste, platinum conductor paste, nickel conductor paste, palladium-silver conductor paste, platinum-silver conductor paste, and the like. The conductive ink (or conductive paste) may be used alone or in combination of two or more.

  The conductive wiring may be formed by, for example, (1) applying conductive ink to a plate formed in a concavo-convex shape in a wiring pattern, and then transferring it to the surface of the porous film, and (2) the surface of the porous film. A conductor paste may be drawn and formed by screen printing. In the methods (1) and (2), if necessary, the formed conductive wiring may be plated using (or applying) a conventional method.

  Further, the conductive wiring may be formed by printing a plating catalyst on the surface of the porous film and plating. The conductive wiring may be formed by, for example, (3) applying a plating catalyst to a plate having an uneven pattern in a wiring pattern, and then transferring and plating the surface of the porous film. A plating catalyst may be drawn on the surface of the material film in the form of a wiring pattern by screen printing and then plated. The plating catalyst may be prepared by, for example, preparing an ink containing the plating catalyst, a suitable vehicle (or particles) and, if necessary, an additive, and printing (or coating) the surface of the porous membrane by a conventional method. Good. Next, the porous film on which the plating catalyst is printed (or coated) may be plated.

  A typical plating catalyst is a metal salt (metal salt) that acts as a catalyst for electroless plating. Specifically, examples of the metals include Group 8 elements of the periodic table (for example, iron), Group 10 elements of the periodic table (for example, nickel, palladium, platinum, etc.), Group 11 elements of the periodic table (for example, For example, gold, silver, copper, etc.) can be mentioned. On the other hand, examples of the salt include organic salts (for example, oxycarboxylates such as citrate and tartrate), inorganic salts (for example, hydrogenates such as hydrochloride and sulfate), and the like. The metal salts can be appropriately combined with the metals and the salt. The metal salts may be used alone or in combination of two or more.

  Also, typical methods for plating include a method in which the plating catalyst is reduced to a metal, and then electroless plating is performed, and if necessary, electroplating is further performed. The reducing agent used for the reduction treatment of the plating catalyst is a conventional reducing agent, for example, sodium borohydride (such as sodium borohydride), lithium aluminum hydride, hypophosphorous acid or a salt thereof (such as sodium salt), Examples thereof include boranes (such as diborane and dimethylamine borane), hydrazine or a salt thereof, and formalin. These reducing agents can be used alone or in combination of two or more. The reduction treatment may be performed using an aqueous solution of the reducing agent of 0.5 to 10% by weight, for example, under conditions of about 20 to 50 ° C. (preferably 25 to 45 ° C.). The electroless plating treatment can be performed by a conventional method, for example, a method using an electroless plating solution such as copper, nickel, and cobalt. The electroplating treatment can also be performed by a conventional method, for example, a method using a copper sulfate plating solution.

  As described above, when the porous film of the present invention (particularly, a laminate with a substrate) is used as a printing medium, excellent print reproducibility (or pattern accuracy) can be exhibited. Or the porous layer) is brittle and the printing ink may peel off. In such a case, as described above, a solvent that is a good solvent for the porous film (or porous layer) and is insoluble in the printing ink is used to dissolve the porous film (or porous layer). When the pores in the porous film are eliminated, a printed matter in which the printing ink and the substrate are firmly adhered (or adhered) can be produced. Furthermore, the transparency of a base material improves and the printed matter by which the pattern was printed clearly (or transferred) can be produced.

  In order to protect the printed matter, a film (a protective layer or a cover lay) may be laminated on one side or both sides (particularly the printed side) of the printed matter. The method for laminating the film on the printed material is not particularly limited, and a conventional method, for example, laminating a film coated with an adhesive (or pressure-sensitive adhesive) on the printed material under heating and / or pressure conditions (or A method of laminating (or laminating) films after applying an adhesive (or pressure-sensitive adhesive) to the printed matter. The type of the film is not particularly limited, but is usually often composed of a thermoplastic resin (for example, a conventional thermoplastic resin such as a polyimide resin or a polyester resin). Also, the adhesive (or pressure-sensitive adhesive) is not particularly limited. For example, an adhesive composed of a thermosetting resin such as an epoxy resin adhesive or a urethane resin adhesive, a polyamide resin adhesive, or a polyester resin. An adhesive composed of a thermoplastic resin such as an adhesive may be used.

  The porous membrane of the present invention can be used in various applications, for example, as separation membranes such as filtration membranes (for example, microfiltration membranes, ultrafiltration membranes, etc.), ion exchange membranes, dialysis membranes, gas separation membranes and the like. In particular, the porous film of the present invention is useful as a printing substrate as described above. For example, a substrate (or porous film) printed using conductive ink (or conductive paste) is useful as various electronic materials (for example, wiring, inductors, light emitters, resistors, capacitors, semiconductors, etc.). It is. In addition, the porous membrane of the present invention is used for various test papers (for example, immunochromatographic test paper, pH test paper, ion concentration test paper, humidity test paper, dryness test paper, bleach (or disinfectant) concentration test paper. Etc.). Furthermore, when the porous film of the present invention is filled with a polymerizable monomer of an electrolyte as a filler and polymerized, an electrolyte film can be formed, and such an electrolyte film is useful as a fuel cell or the like.

  In addition, since the porous membrane of the present invention is excellent in adhesion (or adhesiveness) to a substrate composed of a resin (particularly, a polyethersulfone-based resin), Even the form is effective.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In the examples, comparative examples, and reference examples, the evaluation methods of physical properties are as follows.

(Water vapor supply to the dope)
The amount (or ratio) of water vapor supplied per unit time / unit area was calculated by the following method.

(1) The dope was cast (or coated) to form a film, and the weight of the film (W1 (g)) was measured immediately. (2) The film was placed in a chamber adjusted to a predetermined temperature and humidity. After humidifying for a certain time (T (seconds)), the membrane was taken out of the chamber, and the weight (W2 (g)) of the membrane was measured. (3) Measured weight, humidification time and membrane area S (m ² ) From the following equation, the amount of water vapor (W (g / m ² · sec)) supplied per unit time / unit area was calculated using the following formula (3).

W (g / m ² · sec) = (W2−W1) / (S · T) (3)
In Examples, Comparative Examples, and Reference Examples, the amount of water vapor supplied to the dope was measured at T = 5 seconds.

(Average particle size)
In the electron micrograph of the surface of the porous membrane (or its region or layer) to be measured, 10 or more resin fine particles were arbitrarily selected, the areas of the particles were measured, and the average area S _ave was calculated. Next, assuming that the particles were perfect circles, the average particle diameter was determined from the obtained average area S _ave using the following formula (4). π is the circumference ratio.

Average particle diameter = 2 × (S _ave / π) ^1/2 (4)
(Average pore diameter)
In the electron micrograph of the surface of the porous membrane (or its region or layer) to be measured, 30 or more vacancies were arbitrarily selected to measure the area of the vacancies, and the average area S _ave was calculated. . Next, assuming that the pores are perfect circles, the average pore diameter was determined from the obtained average area S _ave using the following formula (5). π is the circumference ratio.

Average pore diameter = 2 × (S _ave / π) ^1/2 (5)
(Porosity)
The porosity of the porous membrane was calculated using the following formula (6). In the formula, V represents the volume of the porous membrane, W represents the weight of the porous membrane, D represents the density of the porous membrane (or (a) the polyethersulfone-based resin), and D (g / cm ³ ) = 1.37.

Porosity (%) = 100−100 × W / (D · V) (6)
(Gurley air permeability)
Measurement was performed according to JIS P8117 using “PA-301 Gurley Densometer Type B” manufactured by Tester Sangyo Co., Ltd.

(Pure water transmission rate)
Pure water permeation rate, flat film for filter (Amicon Corporation, "STIRRED ULTRAFILTRATION CELLS MODELS 8200" permeation area: 28.7 cm ²⁾ using a temperature 25 ° C., measured at a pressure 0.5 kg / cm ^2. In addition, the filter paper was arrange | positioned on the permeation | transmission side instead of the spacer, the resistance of the permeation | transmission side was excluded, and it measured.

(Tensile modulus, tensile strength and tensile elongation)
According to JIS K 7127, it was measured using a universal tensile testing machine (Orientec, “Tensilon RTA500”).

[Example 1]
A polyethersulfone resin (manufactured by BASF Japan) having a viscosity of 2300 cps (2.3 Pa · s) under the conditions of 6 rpm and 23 ° C. as a polyethersulfone resin in a 20 wt% N-methyl-2-pyrrolidone solution , “E6020”) as a hydrophilic polymer, polyethylene glycol 200 (manufactured by Kishida Chemical Co., Ltd., “polyethylene glycol 200”) as a solvent, and N-methyl-2-pyrrolidone as a solvent. 35 parts by weight of a polyethersulfone resin was dissolved in 65 parts by weight of N-methyl-2-pyrrolidone. 170 parts by weight of polyethylene glycol 200 was added to the obtained polyethersulfone resin solution and stirred to prepare a dope. The obtained dope (viscosity 2100 cps under conditions of 6 rpm and 23 ° C.) was cast on a polyethylene terephthalate (PET) film, and then humidified for 5 seconds at a relative humidity of 90% RH and a temperature of 30 ° C., and 30 g / m ^2. Water vapor was supplied at a rate of 1 second, placed in a coagulation tank (water) for 1 minute, and dried to obtain a porous film (thickness 34 μm). The obtained film was observed using a scanning electron microscope (SEM). Front surface photograph (FIG. 4), back surface (PET film surface) photograph (FIG. 5), film cross-sectional photograph (FIG. 6), surface layer enlarged cross-sectional photograph (FIG. 7), and intermediate layer enlarged cross-sectional photograph (FIG. 8) and an enlarged sectional photograph (FIG. 9) of the back layer are shown. Using the photograph, the particle diameter of the part observed in the form of particles and the hole diameter of the pores were measured. The results are shown in Table 1. The average value of the measured average particle diameters dA to dE was 0.21 μm, the average value of the average pore diameters φA to φE was 0.53 μm, and the porosity was 77%. The porous film thus obtained had a Gurley air permeability of 7 seconds / 100 ml, a pure water transmission rate of 111600 L / m ² · h · MPa, a tensile modulus of 140 MPa, and a tensile elongation of 10%.

[Example 2]
A porous membrane (thickness 46 μm) was obtained in the same manner as in Example 1 except that 150 parts by weight of polyethylene glycol 200 was used instead of 170 parts by weight. The obtained film was observed using a scanning electron microscope (SEM). Using the obtained photograph, the particle diameter of the part observed in the form of particles and the hole diameter of the pores were measured. The results are shown in Table 1. The average value of the measured average particle diameters dA to dE was 0.21 μm, the average value of the average pore diameters φA to φE was 0.54 μm, and the porosity was 72%. The porous film thus obtained had a Gurley air permeability of 7 seconds / 100 ml, 78800 L / m ² · h · MPa, a tensile modulus of 150 MPa, and a tensile elongation of 8%.

[Comparative Example 1]
An attempt was made to produce a porous membrane in the same manner as in Example 1 except that 200 parts by weight of polyvinyl pyrrolidone was used instead of 170 parts by weight of polyethylene glycol 200, but the dope could not be uniformly dissolved and solidified.

[Comparative Example 2]
The amount of polyethylene glycol 200 used is 80 parts by weight instead of 170 parts by weight, the humidification time is 10 seconds instead of 5 seconds, and steam is supplied at a rate of 25 g / m ² · second. A porous membrane (thickness 25 μm) was obtained in the same manner as in Example 1 except for humidification. When the obtained film was observed using a scanning electron microscope (SEM), an aggregate of resin fine particles was not formed on the back surface of the film, and the film was an asymmetric film. Using the obtained photograph, the particle diameter of the part observed in the form of particles and the hole diameter of the pores were measured. The results are shown in Table 1. The resulting membrane had a porosity of 57%, a Gurley permeability of 53 seconds / 100 ml, a pure water transmission rate of 13300 L / m ² · h · MPa, a tensile modulus of 210 MPa, and a tensile elongation of 8%. there were.

[Comparative Example 3]
Instead of the polyethersulfone resin, a polysulfone resin (“Udel 1700P” manufactured by Solvay Advanced Polymers Co., Ltd. (viscosity of 20 wt% N-methyl-2-pyrrolidone solution is 200 cps (0.2 Pa · s))] is used. Then, except that 200 parts by weight of polyethylene glycol 200 was used, an attempt was made to produce a porous membrane in the same manner as in Example 1. However, a polysulfone-based resin was precipitated, and a uniform dope was not obtained and gelled.

[Comparative Example 4]
A polyethersulfone resin (manufactured by BASF Japan) having a viscosity of 2300 cps (2.3 Pa · s) under the conditions of 6 rpm and 23 ° C. as a polyethersulfone resin in a 20 wt% N-methyl-2-pyrrolidone solution , “E6020”) as a hydrophilic polymer, polyethylene glycol 200 (manufactured by Kishida Chemical Co., Ltd., “polyethylene glycol 200”) as a solvent, and N-methyl-2-pyrrolidone as a solvent. 11 parts by weight of a polyethersulfone resin was dissolved in 23.9 parts by weight of N-methyl-2-pyrrolidone. To the obtained polyethersulfone resin solution, 65.1 parts by weight of polyethylene glycol 200 was added and stirred to prepare a dope. The obtained dope (viscosity 2000 cps (2 Pa · s) under conditions of 6 rpm and 23 ° C.) was cast on a polyethylene terephthalate (PET) film, and then humidified for 5 seconds at a relative humidity of 75% RH and a temperature of 30 ° C. Water vapor was supplied at a rate of 0.7 g / m ² · sec, placed in a coagulation tank (water) for 1 minute, and dried to obtain a porous film (thickness 26 μm). When the obtained film was observed using a scanning electron microscope (SEM), an aggregate of resin fine particles was not formed on the back surface of the film, and the film was an asymmetric film. The surface photograph (FIG. 10) and back (PET film surface) photograph (FIG. 11) of the obtained film are shown. Using the obtained photograph, the particle diameter of the part observed in the form of particles and the hole diameter of the pores were measured. The results are shown in Table 1. The obtained membrane had a porosity of 62%, a Gurley permeability of 22 seconds / 100 ml, a pure water transmission rate of 12200 L / m ² · h · MPa, a tensile modulus of 170 MPa, and a tensile elongation of 9%. there were.

  As is clear from Table 1, (b) polyethylene glycol and (c) N-methyl-2-pyrrolidone were used in specific ratios, and in the examples humidified under specific humidification conditions, they were homogeneous in the thickness direction. A porous membrane was obtained. On the other hand, in the comparative example, the porosity was greatly different between the front surface and the back surface of the film, and a dense layer was formed on the back surface.

[Example 3, Reference Example 1 and Comparative Example 5]
The dope blended with the polyethersulfone resin, polyethylene glycol 200 and N-methyl-2-pyrrolidone at the ratio shown in Table 2 is a polyethersulfone film (PES) (manufactured by Sumitomo Bakelite Co., Ltd., “Sumilite (registered trademark)”). FS1300 ”, thickness 50 μm), humidified for 5 seconds at a relative humidity of 90% RH and a temperature of 30 ° C., supplied with water vapor at a rate of 30 g / m ² · second, placed in a coagulation tank (water) for 1 minute, and dried. To obtain a laminate (total thickness 85 μm). About the obtained laminated body, the presence or absence of peeling of a porous layer was observed and adhesiveness was evaluated. The results are shown in Table 2.

  As is clear from Table 2, when (b) polyethylene glycol and (c) N-methyl-2-pyrrolidone are used in a specific ratio, the adhesion between the porous membrane and the substrate is improved in the resulting laminate. It was good.

[Example 4]
An uncured silicone resin [manufactured by Toray Dow Corning Co., Ltd., two-component curable silicone resin (main solvent: CY-52-205, curing agent: CY-52], which is formed on the porous film (thickness 44 μm) obtained in Example 1. -205-CAT, main solvent / curing agent (weight ratio) = 10/1), tensile modulus 1.82 MPa, tensile strength 5 MPa, tensile elongation 151%] was applied with an applicator (manufactured by Tester Sangyo Co., Ltd.). Then, the silicone resin was cured by heating at 150 ° C. for 30 minutes. The tensile modulus, tensile strength, and tensile elongation of the porous membrane (functional membrane) filled with the silicone resin were measured. The results are shown in Table 3.

  As apparent from Table 3, the tensile modulus of the porous membrane (functional membrane) filled with the silicone resin is 28.7 MPa, which is about 16 times that of the case of the silicone resin alone. Improved.

[Example 5]
On the porous film obtained in Example 3, a plate and printing ink having an image line width (L1) of 100 μm (conducting paint “CA-2503” manufactured by Daiken Chemical Industry Co., Ltd. (main solvent: butyl) After printing, the ink was dried at 100 ° C. for 30 minutes, and the line width (average width at a length of 1000 μm) (L2) using a scanning electron microscope (SEM) The width (L2) was 96 μm and L2 / L1 = 0.96 A photograph (100 times) of the printed surface of the obtained printed matter is shown in FIG. In addition, printing with excellent pattern accuracy was obtained.

[Comparative Example 6]
Screen printing was performed in the same manner as in Example 5 except that a polyethersulfone film (manufactured by Sumitomo Bakelite Co., Ltd., “Sumilite (registered trademark) FS1300”, thickness 50 μm) was used instead of the porous membrane obtained in Example 1. Went. The line width (L2) was 174 μm, and L2 / L1 = 1.74. The photograph (100 times) of the printing surface of the obtained printed matter is shown in FIG. As is clear from FIG. 13, the pattern accuracy was inferior in Comparative Example 6.

[Example 6]
Example 5 A mixed solvent of γ-butyrolactone and isopropanol (γ-butyrolactone / isopropanol (weight ratio) = 50/50) was impregnated into the nonwoven fabric at a rate of 16 g per 1 m ^{2 of the} nonwoven fabric. Then, the mixed solvent was transferred to the printed material, and then the solvent was removed, dried at 80 ° C. for 5 minutes, and further dried at 150 ° C. for 5 minutes. By drying, the porous layer became transparent, and the disappearance of the pores in the porous layer was confirmed. When the cellophane tape peeling test was performed, in which the cellophane tape was applied to the printed matter from which the pores of the porous layer had disappeared, the printing ink did not adhere to the cellophane tape, and the printing ink did not peel off.

[Reference Example 2]
When the cellophane tape peeling test was performed on the printed matter obtained in Example 5 without losing the pores of the porous layer, the printing ink and the porous layer adhered to the cellophane tape.

[Comparative Example 7]
When the cellophane tape peeling test was performed on the printed matter obtained in Comparative Example 6 without losing the pores of the porous layer, the printing ink and the porous layer adhered to the cellophane tape, and the printing ink and the porous layer The destruction of was confirmed.

[Example 7]
An epoxy resin adhesive layer and a polyimide resin film were formed on the porous membrane surface of the laminate (a laminate of a polyethersulfone resin porous membrane and a polyethersulfone (PES) film) obtained in Example 3. The adhesive layer of the coverlay [Nikkan Kogyo Co., Ltd. make, Nikaflex CISV1225] comprised by the layer was laminated | stacked over 60 minutes on 160 degreeC and 2 MPa conditions. When the obtained laminate was visually observed, no lamination (or adhesion) unevenness was observed, and the adhesive melted with the porous layer and became transparent. Also, according to JIS-C-6471 “Adhesion evaluation by 180 degree peeling”, the laminate was cut into a 1 cm wide strip, and the coverlay and the base film (polyethersulfone film) were peeled off to adhere ( (Or tensile) strength was 770 gf / cm.

[Reference Example 3]
Instead of a laminate of a polyethersulfone-based porous film and a polyethersulfone film (PES), a polyamideimide-based resin (Toyobo's “Vilomax HR11NN”) porous film and a polyimide (PI) film A coverlay was laminated in the same manner as in Example 7 except that a laminate with Toray DuPont ("Kapton 200H") was used. When the obtained laminate was visually observed, no lamination (or adhesion) unevenness was observed, and the adhesive melted with the porous layer and became transparent. Further, the adhesion (or tensile) strength was 740 gf / cm.

[Reference Example 4]
Instead of a laminate of a polyethersulfone resin porous membrane and a polyethersulfone film (PES), a polyetherimide resin (manufactured by GE Plastics Co., Ltd., "ULTEM1000") porous membrane and poly A coverlay was laminated in the same manner as in Example 7 except that a laminate with an etherimide (PEI) film (Mitsubishi Resin, “Superio UT”) was used. When the obtained laminate was visually observed, no lamination (or adhesion) unevenness was observed, and the adhesive melted with the porous layer and became transparent. Further, the adhesion (or tensile) strength was 750 gf / cm.

[Reference Example 5]
A mixed solvent of γ-butyrolactone and methyl ethyl ketone (γ-butyrolactone / methyl ethyl ketone (weight ratio) = 50/50) was immersed in the nonwoven fabric at a rate of 16 g per 1 m ^{2 of the} nonwoven fabric, and the nonwoven fabric was referred to Reference Example 4. The mixed solvent was transferred to the printed material, the pores of the porous layer disappeared, dried at 80 ° C. for 10 minutes, and further dried at 150 ° C. for 10 minutes. Next, a coverlay was laminated in the same manner as in Example 7. When the obtained laminate was visually observed, no lamination (or adhesion) unevenness was observed. The adhesion (or tensile) strength was 590 gf / cm.

FIG. 1 is a schematic cross-sectional schematic view showing the particle structure of the porous layer of the present invention. FIG. 2 is a schematic cross-sectional view showing the pore structure of the porous layer of the present invention. FIG. 3 is a schematic diagram showing measurement sites of the particle diameter (dA to dE) and the pore diameter (φA to φE) of the porous membrane of the present invention. FIG. 4 is a photograph showing the surface of the porous membrane obtained in Example 1. The scale bar in the figure indicates 1.2 μm. FIG. 5 is a photograph showing the back surface of the porous membrane obtained in Example 1. The scale bar in the figure indicates 1.2 μm. 6 is a cross-sectional photograph of the porous membrane obtained in Example 1. FIG. The scale bar in the figure indicates 10 μm. FIG. 7 is an enlarged cross-sectional photograph of the surface layer of the porous membrane obtained in Example 1. The scale bar in the figure indicates 1.2 μm. FIG. 8 is an enlarged cross-sectional photograph of the intermediate layer of the porous membrane obtained in Example 1. The scale bar in the figure indicates 1.2 μm. FIG. 9 is an enlarged cross-sectional photograph of the back layer of the porous film obtained in Example 1. The scale bar in the figure indicates 1.2 μm. FIG. 10 is a photograph showing the surface of the porous membrane obtained in Comparative Example 4. The scale bar in the figure indicates 1 μm. FIG. 11 is a photograph showing the back surface of the porous film obtained in Comparative Example 4. The scale bar in the figure indicates 1 μm. FIG. 12 is a photograph of the printed surface of the printed matter obtained in Example 5. The scale bar in the figure indicates 1 mm. FIG. 13 is a photograph of the printed surface of the printed matter obtained in Comparative Example 6. The scale bar in the figure indicates 1 mm.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Resin particle 2 ... Virtual circle of hole 3 ... Front surface 4 ... Back surface 5 ... Surface layer 6 ... Intermediate layer 7 ... Back surface layer 8 ... Porous film 9 ... Printed part (or image line part)

Claims (13)

A dope containing (a) a polyethersulfone-based resin, (b) a hydrophilic polymer, and (c) a solvent is formed, humidified and solidified, and the (b) hydrophilic polymer and the (c) A method for producing a porous membrane composed of (a) a polyethersulfone-based resin by removing a solvent, wherein (b) a hydrophilic polymer and (c) a solvent are mixed with the former / the latter (weight) Ratio) = 1.5 / 1 to 2.7 / 1, and the dope is humidified by supplying water vapor at a rate of 1 to 1000 g / m ² · sec. A method for producing a porous membrane by coagulating a sulfone resin. (B) A hydrophilic polymer and (c) solvent are used in a ratio of the former / the latter (weight ratio) = 1.6 / 1 to 2.5 / 1, and 5 to 300 g / m with respect to the dope. The manufacturing method according to claim 1, wherein the steam is supplied and humidified at a rate of ² · sec.   The production method according to claim 1 or 2, wherein the humidification time is 0.1 to 10 seconds.   The content of (a) the polyethersulfone resin is 5 to 20% by weight based on the total amount of (a) the polyethersulfone resin, (b) the hydrophilic polymer, and (c) the solvent. The manufacturing method in any one of 1-3.   (B) The number average molecular weight of hydrophilic polymer is 100-2,000, The manufacturing method in any one of Claims 1-4.   The production method according to claim 1, wherein the dope is cast on a substrate to form a film, and the porous film is separated from the substrate.   The manufacturing method according to claim 1, wherein a dope is applied to a substrate to form a film, and a porous film laminated on the substrate is manufactured.   The production method according to claim 7, wherein the substrate is composed of a polyethersulfone resin.   The porous membrane obtained by the manufacturing method in any one of Claims 1-8.   The porous film according to claim 9, wherein the porosity is 40 to 90%.   The porous membrane according to claim 9 or 10, further comprising a filler in the pores of the porous membrane.   The laminated body comprised with the base material and the porous membrane in any one of Claims 9-11 laminated | stacked on this base material.   The laminate according to claim 12, wherein the porous membrane has a thickness of 1 to 200 µm, and the substrate is composed of a polyethersulfone resin.