WO2017038897A1 - 多孔質膜の製造方法 - Google Patents
多孔質膜の製造方法 Download PDFInfo
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- WO2017038897A1 WO2017038897A1 PCT/JP2016/075570 JP2016075570W WO2017038897A1 WO 2017038897 A1 WO2017038897 A1 WO 2017038897A1 JP 2016075570 W JP2016075570 W JP 2016075570W WO 2017038897 A1 WO2017038897 A1 WO 2017038897A1
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/26—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a solid phase from a macromolecular composition or article, e.g. leaching out
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/56—Polyamides, e.g. polyester-amides
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/58—Other polymers having nitrogen in the main chain, with or without oxygen or carbon only
- B01D71/62—Polycondensates having nitrogen-containing heterocyclic rings in the main chain
- B01D71/64—Polyimides; Polyamide-imides; Polyester-imides; Polyamide acids or similar polyimide precursors
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/66—Polymers having sulfur in the main chain, with or without nitrogen, oxygen or carbon only
- B01D71/68—Polysulfones; Polyethersulfones
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
- B29C41/02—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor for making articles of definite length, i.e. discrete articles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
- B29C41/34—Component parts, details or accessories; Auxiliary operations
- B29C41/46—Heating or cooling
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- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/20—Compounding polymers with additives, e.g. colouring
- C08J3/205—Compounding polymers with additives, e.g. colouring in the presence of a continuous liquid phase
- C08J3/21—Compounding polymers with additives, e.g. colouring in the presence of a continuous liquid phase the polymer being premixed with a liquid phase
- C08J3/212—Compounding polymers with additives, e.g. colouring in the presence of a continuous liquid phase the polymer being premixed with a liquid phase and solid additives
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- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/20—Compounding polymers with additives, e.g. colouring
- C08J3/205—Compounding polymers with additives, e.g. colouring in the presence of a continuous liquid phase
- C08J3/21—Compounding polymers with additives, e.g. colouring in the presence of a continuous liquid phase the polymer being premixed with a liquid phase
- C08J3/215—Compounding polymers with additives, e.g. colouring in the presence of a continuous liquid phase the polymer being premixed with a liquid phase at least one additive being also premixed with a liquid phase
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/24—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by surface fusion and bonding of particles to form voids, e.g. sintering
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/36—After-treatment
- C08J9/365—Coating
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L79/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen or carbon only, not provided for in groups C08L61/00 - C08L77/00
- C08L79/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
- C08L79/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L81/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing sulfur with or without nitrogen, oxygen or carbon only; Compositions of polysulfones; Compositions of derivatives of such polymers
- C08L81/06—Polysulfones; Polyethersulfones
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- B29L2007/00—Flat articles, e.g. films or sheets
- B29L2007/008—Wide strips, e.g. films, webs
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2201/00—Foams characterised by the foaming process
- C08J2201/04—Foams characterised by the foaming process characterised by the elimination of a liquid or solid component, e.g. precipitation, leaching out, evaporation
- C08J2201/044—Elimination of an inorganic solid phase
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
- C08J2367/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2377/00—Characterised by the use of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Derivatives of such polymers
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2379/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2361/00 - C08J2377/00
- C08J2379/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
- C08J2379/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2381/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing sulfur with or without nitrogen, oxygen, or carbon only; Polysulfones; Derivatives of such polymers
- C08J2381/06—Polysulfones; Polyethersulfones
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2477/00—Characterised by the use of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Derivatives of such polymers
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2479/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2461/00 - C08J2477/00
- C08J2479/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
- C08J2479/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
Definitions
- the present invention relates to a method for producing a porous membrane.
- a varnish in which silica particles are dispersed in a polymer solution of polyamic acid or polyimide is applied on a substrate, and then the coated film is heated as necessary.
- a method of obtaining a polyimide film containing silica particles, and then elution and removing silica in the polyimide film with hydrogen fluoride water to make it porous see Patent Document 1.
- the filter grain removal effect is generally determined by the sieving effect and the adsorption effect.
- it is effective to reduce the pore diameter and increase the specific surface area.
- a varnish containing fine particles having a small particle size By using a varnish containing fine particles having a small particle size, a porous film having a small pore diameter and a large specific surface area can be formed.
- fine particles such as fine silica particles having an average particle diameter of about 200 nm, for example, tend to aggregate in the varnish and are difficult to disperse uniformly.
- the dispersibility of the fine particles is improved to some extent by the addition of a dispersant.
- the finer the fine particles the more limited the effect of the dispersant. Therefore, it has been difficult to obtain a porous film in which micropores having a minute diameter (for example, about 200 nm) are uniformly formed.
- the present invention has been made in view of the above situation, and even when using fine particles, after preparing a varnish in which fine particles are well dispersed, a porous film can be produced using the varnish. It aims at providing the manufacturing method of a porous membrane.
- a varnish containing at least one resin component selected from the group consisting of polyamic acid, polyimide, polyamideimide precursor, polyamideimide and polyethersulfone and fine particles
- a first aspect of the present invention is a method for producing a porous membrane, wherein at least one resin component selected from the group consisting of fine particles, polyamic acid, polyimide, polyamideimide precursor, polyamideimide, and polyethersulfone
- a method for producing a porous membrane comprising the step of dispersing a slurry containing fine particles by shearing force and compressive force or impact force. is there.
- the second aspect of the present invention is: Preparing a slurry (1) comprising fine particles and a solvent, Preparing a varnish (1) comprising at least one resin component selected from the group consisting of polyamic acid, polyimide, polyamideimide precursor, polyamideimide and polyethersulfone, and a solvent; A process for preparing a slurry (2) by kneading a slurry (1) and a varnish (1), and a process for dispersing the slurry (2) by shearing force and compressive force or impact force. It is a manufacturing method of a composition.
- FIG. 1 is a view showing a scanning electron microscope image of a coating film formed using the composition for producing a porous membrane prepared in Example 1.
- FIG. (A) is a figure which shows the scanning electron microscope image of the coating film formed using the composition for porous film manufacture prepared in the comparative example 1
- (b) is a scanning electron from which the magnification of the coating film differs. It is a figure which shows a microscope image.
- 6 is a view showing a scanning electron microscope image of the surface of the porous film obtained in Example 5.
- FIG. 6 is a view showing a scanning electron microscope image of the surface of a porous film obtained in Comparative Example 2.
- a method for producing a porous membrane includes a step of preparing a porous membrane-producing composition containing fine particles and a resin component (hereinafter sometimes simply referred to as a varnish), and shearing the slurry containing the fine particles, A dispersing step of dispersing by compressive force or impact force.
- a resin component at least one selected from the group consisting of polyamic acid, polyimide, polyamideimide precursor, polyamideimide, and polyethersulfone is used.
- the preparation process of the composition for porous membrane manufacture is demonstrated.
- the preparation process of the composition for producing a porous film includes a dispersion process in which the slurry containing fine particles is dispersed by a shearing force and a compressive force or an impact force.
- a high shearing dispersion device such as a three-roll mill is preferably used as a device for dispersing fine particles in the slurry by the shearing force and the impact force.
- an apparatus such as a planetary mixer is sufficient to disperse fine particles having a relatively large average particle diameter.
- the fine particles having a small average particle diameter of 200 nm or less are used. Is insufficient to disperse. Even if fine particles with a small average particle size are dispersed by dispersing the fine particles in the slurry by shearing force and compressive force or impact force, the fine particles are uniformly dispersed while suppressing reaggregation of the dispersed fine particles. Can be made.
- the average particle diameter of the fine particles is preferably 200 nm or less, and more preferably 160 nm or less.
- the size of the pores derived from the fine particles formed in the porous membrane is the same as or close to the average particle size of the fine particles.
- the average particle diameter of the fine particles is preferably 5 nm or more, and more preferably 10 nm or more, from the viewpoint of fluid permeability when the porous membrane is used as a filter.
- the fine particles preferably have a high sphericity and a small particle size distribution index. The fine particles having these conditions are excellent in dispersibility in the varnish and can be used in a state where they do not aggregate with each other.
- the content of fine particles in the slurry is, for example, 5 to 95% by mass, preferably 20 to 90% by mass, and more preferably 30 to 85% by mass with respect to the mass of the slurry.
- the content of the fine particles is within the above range, the fine particles are unlikely to aggregate in the varnish, and it is easy to form a porous film without causing cracks on the surface. Can be manufactured.
- the step of preparing the composition for producing a porous membrane is selected from the group consisting of a step of preparing a slurry (1) containing fine particles and a solvent, polyamic acid, polyimide, polyamideimide precursor, polyamideimide and polyethersulfone.
- a step of dispersing by compressive force or impact force is selected from the group consisting of a step of preparing a slurry (1) containing fine particles and a solvent, polyamic acid, polyimide, polyamideimide precursor, polyamideimide and polyethersulfone.
- the solid content concentration of the slurry (2) is not particularly limited, but is, for example, 10% by mass or more, preferably 30% by mass or more, The upper limit is, for example, 60% by mass or less.
- the solid content concentration of the slurry (2) is not particularly limited, but is, for example, 1% by mass or more, preferably 5% by mass or more.
- the upper limit is, for example, 60% by mass or less.
- the slurry (2) is kneaded by centrifugal force, such as kneading the slurry (2) with a rotating / revolving mixer, as a pre-step of the step of dispersing the slurry (2) by shearing force and compressive force or impact force.
- centrifugal force such as kneading the slurry (2) with a rotating / revolving mixer
- the preparation step is performed only by shearing force such as kneading the slurry (2) with a planetary mixer as a pre-step of dispersing the slurry (2) by shearing force and compression force or impact force.
- shearing force such as kneading the slurry (2) with a planetary mixer
- the step of preparing the composition for producing a porous membrane includes a step of preparing a slurry (1) containing fine particles and a solvent, a step of dispersing the slurry (1) by shearing force and compressive force or impact force, polyamic acid, A step of preparing a varnish (1) containing at least one resin component selected from the group consisting of a polyimide, a polyamideimide precursor, a polyamideimide and a polyethersulfone, and a solvent; and a slurry (1) that has undergone a dispersion step You may have the process of knead
- the solid content concentration of the slurry (2) is not particularly limited, but is, for example, 10% by mass or more, preferably 30% by mass or more, The upper limit is, for example, 90% by mass or less.
- the solid content concentration of the slurry (2) is not particularly limited, but is, for example, 1% by mass or more, preferably 5% by mass or more.
- the upper limit is, for example, 90% by mass or less.
- the preparation step includes a step of dispersing the slurry (1) by an impact force such as dispersing the slurry (1) by a homogenizer as a pre-step of the step of dispersing the slurry (1) by a shearing force and a compressive force or an impact force. Good.
- the slurry (1) and the varnish (1) are kneaded with a rotating / revolving mixer as a pre-process of the step of kneading the slurry (1) and the varnish (1) that have undergone the dispersion step.
- a step of kneading the slurry is kneaded with a rotating / revolving mixer as a pre-process of the step of kneading the slurry (1) and the varnish (1) that have undergone the dispersion step.
- the preparation step has a step of dispersing again by a shearing force and a compressive force or an impact force as a subsequent step of the step of kneading the slurry (1) and the varnish (1) that have undergone the dispersing step. It's okay.
- the preparation process of the composition for producing a porous membrane includes, for example, a slurry containing fine particles and at least one resin component selected from the group consisting of polyamic acid, polyimide, polyamideimide precursor, polyamideimide and polyethersulfone.
- Viscosity of lowering the viscosity of slurry (3) by preparing (3), adding a solvent to the slurry (3) subjected to the dispersing step and the step of dispersing the slurry (3) by shearing force and compressive force or impact force There may be a preparation step.
- the viscosity adjusting step it is preferable that the viscosity of the slurry (3) is adjusted to 5 Pa ⁇ s or less.
- the slurry (3) in the dispersion step has a high viscosity, for example, exceeds 5 Pa ⁇ s, the fine particles are more efficiently dispersed by shearing force and compressive force or impact force. It will be easier.
- the solid content concentration of the slurry (3) is not particularly limited, but is, for example, 10% by mass or more, preferably 30% by mass or more, The upper limit is, for example, 60% by mass or less.
- the solid content concentration of the slurry (2) is not particularly limited, but is, for example, 1% by mass or more, preferably 5% by mass or more.
- the upper limit is, for example, 60% by mass or less.
- the varnish contains at least one selected from the group consisting of polyamic acid, polyimide, polyamideimide precursor, polyamideimide, and polyethersulfone as a resin component.
- polyamic acid polyimide
- polyamideimide precursor polyamideimide
- polyethersulfone polyethersulfone
- polyamic acid a product obtained by polymerizing any tetracarboxylic dianhydride and diamine can be used without any particular limitation.
- the amount of tetracarboxylic dianhydride and diamine used is not particularly limited, but 0.50 to 1.50 mol of diamine is preferably used relative to 1 mol of tetracarboxylic dianhydride, and 0.60 to 1. It is more preferable to use 30 mol, and it is particularly preferable to use 0.70 to 1.20 mol.
- the tetracarboxylic dianhydride can be appropriately selected from tetracarboxylic dianhydrides conventionally used as raw materials for polyamic acid synthesis.
- the tetracarboxylic dianhydride may be an aromatic tetracarboxylic dianhydride or an aliphatic tetracarboxylic dianhydride. From the viewpoint of the heat resistance of the resulting polyimide resin, the aromatic tetracarboxylic dianhydride may be used. Preference is given to using carboxylic dianhydrides.
- a tetracarboxylic dianhydride may be used individually by 1 type, and may be used in combination of 2 or more type.
- aromatic tetracarboxylic dianhydride examples include pyromellitic dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxy Phenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′- Biphenyltetracarboxylic dianhydride, 2,2,6,6-biphenyltetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2 , 3-dicarboxyphenyl) propane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-
- aliphatic tetracarboxylic dianhydride examples include, for example, ethylene tetracarboxylic dianhydride, butane tetracarboxylic dianhydride, cyclopentane tetracarboxylic dianhydride, cyclohexane tetracarboxylic dianhydride, 1, 2, Examples include 4,5-cyclohexanetetracarboxylic dianhydride and 1,2,3,4-cyclohexanetetracarboxylic dianhydride. Among these, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and pyromellitic dianhydride are preferable from the viewpoints of price and availability. Moreover, these tetracarboxylic dianhydrides can also be used individually by 1 type or in mixture of 2 or more types.
- the diamine can be appropriately selected from diamines conventionally used as a raw material for synthesizing polyamic acid.
- the diamine may be an aromatic diamine or an aliphatic diamine, but an aromatic diamine is preferred from the viewpoint of the heat resistance of the resulting polyimide resin. These diamines may be used alone or in combination of two or more.
- aromatic diamines include diamino compounds in which one or about 2 to 10 phenyl groups are bonded. Specifically, phenylenediamine and derivatives thereof, diaminobiphenyl compounds and derivatives thereof, diaminodiphenyl compounds and derivatives thereof, diaminotriphenyl compounds and derivatives thereof, diaminonaphthalene and derivatives thereof, aminophenylaminoindane and derivatives thereof, diaminotetraphenyl Compounds and derivatives thereof, diaminohexaphenyl compounds and derivatives thereof, and cardo-type fluorenediamine derivatives.
- Phenylenediamine is m-phenylenediamine, p-phenylenediamine, etc., and phenylenediamine derivatives include diamines to which alkyl groups such as methyl group and ethyl group are bonded, such as 2,4-diaminotoluene, 2,4-triphenylene. Diamines and the like.
- diaminobiphenyl compound two aminophenyl groups are bonded to each other.
- diaminobiphenyl compound two aminophenyl groups are bonded to each other.
- a diaminodiphenyl compound is a compound in which two aminophenyl groups are bonded to each other via other groups.
- the bond is an ether bond, a sulfonyl bond, a thioether bond, a bond by alkylene or a derivative group thereof, an imino bond, an azo bond, a phosphine oxide bond, an amide bond, a ureylene bond, or the like.
- the number of carbon atoms of the alkylene bond is about 1 to 6.
- the derivative group of an alkylene group is an alkylene group substituted with one or more halogen atoms and the like.
- diaminodiphenyl compounds include 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl sulfone, 3,4′-diaminodiphenyl sulfone, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl ketone 3,4′-diaminodiphenyl ketone, 2,2-bis (p-aminophenyl) propane, 2,2′-bis (p-aminophenyl) hexafluor
- p-phenylenediamine p-phenylenediamine, m-phenylenediamine, 2,4-diaminotoluene, and 4,4'-diaminodiphenyl ether are preferable from the viewpoint of price and availability.
- a diaminotriphenyl compound is a compound in which two aminophenyl groups and one phenylene group are bonded via another group. As other groups, the same groups as in the diaminodiphenyl compound are selected. Examples of diaminotriphenyl compounds include 1,3-bis (m-aminophenoxy) benzene, 1,3-bis (p-aminophenoxy) benzene, 1,4-bis (p-aminophenoxy) benzene, and the like. be able to.
- diaminonaphthalene examples include 1,5-diaminonaphthalene and 2,6-diaminonaphthalene.
- aminophenylaminoindane examples include 5 or 6-amino-1- (p-aminophenyl) -1,3,3-trimethylindane.
- diaminotetraphenyl compounds examples include 4,4′-bis (p-aminophenoxy) biphenyl, 2,2′-bis [p- (p′-aminophenoxy) phenyl] propane, 2,2′-bis [ and p- (p′-aminophenoxy) biphenyl] propane, 2,2′-bis [p- (m-aminophenoxy) phenyl] benzophenone, and the like.
- cardo-type fluorenediamine derivatives include 9,9-bisaniline fluorene.
- the number of carbon atoms in the aliphatic diamine is preferably about 2 to 15, for example.
- Specific examples of the aliphatic diamine include pentamethylene diamine, hexamethylene diamine, and heptamethylene diamine.
- a compound in which the hydrogen atom of these diamines is substituted with at least one substituent selected from the group such as a halogen atom, a methyl group, a methoxy group, a cyano group, and a phenyl group may be used.
- the means for producing the polyamic acid is not particularly limited, and for example, a known method such as a method of reacting an acid and a diamine component in a solvent can be used.
- the reaction between tetracarboxylic dianhydride and diamine is usually carried out in a solvent.
- the solvent used for the reaction of tetracarboxylic dianhydride and diamine is particularly limited as long as it can dissolve tetracarboxylic dianhydride and diamine and does not react with tetracarboxylic dianhydride and diamine. Not.
- a solvent may be used individually by 1 type and may be used in combination of 2 or more type.
- Examples of the solvent used for the reaction of tetracarboxylic dianhydride and diamine include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, N, Nitrogen-containing polar solvents such as N-diethylformamide, N-methylcaprolactam, N, N, N ′, N′-tetramethylurea; ⁇ -propiolactone, ⁇ -butyrolactone, ⁇ -valerolactone, ⁇ -valerolactone, Lactone polar solvents such as ⁇ -caprolactone and ⁇ -caprolactone; dimethyl sulfoxide; acetonitrile; fatty acid esters such as ethyl lactate and butyl lactate; diethylene glycol dimethyl ether, diethylene glycol diethyl ether, dioxane, tetrahydrofuran, methyl cellosolve acetate
- N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, N, N-diethyl are considered because of the solubility of the resulting polyamic acid.
- Nitrogen-containing polar solvents such as formamide, N-methylcaprolactam, N, N, N ′, N′-tetramethylurea are preferred.
- the polymerization temperature is generally ⁇ 10 to 120 ° C., preferably 5 to 30 ° C.
- the polymerization time varies depending on the raw material composition used, but is usually 3 to 24 Hr (hour).
- a polyamic acid may be used individually by 1 type, and may be used in combination of 2 or more type.
- Polyimide The structure and molecular weight of the polyimide are not limited, and known ones can be used. About a polyimide, you may have a functional group which accelerates
- ethylenediamine hexamethylenediamine, 1,4-diaminocyclohexane, 1,3-diaminocyclohexane
- 4 Aliphatic diamines such as 2,4'-diaminodicyclohexylmethane; 2-methyl-1,4-phenylenediamine, o-tolidine, m-tolidine, 3,3'-dimethoxybenzidine, 4,4'-diaminobenzanilide, etc.
- Aromatic diamines such as polyoxyethylene diamine, polyoxypropylene diamine and polyoxybutylene diamine; polysiloxane diamines; 2,3,3 ′, 4′-oxydiphthalic anhydride, 3,4,3 ′, 4'-oxydiphthalic anhydride, 2,2-bis (4-hydroxypheny E) Use of propanedibenzoate-3,3 ′, 4,4′-tetracarboxylic dianhydride is effective.
- a monomer having a functional group that improves solubility in a solvent such as 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl, 2-trifluoromethyl-1,4- It is also effective to use a fluorinated diamine such as phenylenediamine.
- the same monomer as the monomer described in the column of the polyamic acid can be used in combination as long as the solubility is not inhibited.
- Each of the polyimide and its monomer may be used alone or in combination of two or more.
- a polyimide there is no restriction
- well-known methods such as the method of chemically imidating or heat imidating a polyamic acid, can be used.
- polyimide include aliphatic polyimide (total aliphatic polyimide), aromatic polyimide and the like, and aromatic polyimide is preferable.
- aromatic polyimide include those obtained by subjecting a polyamic acid having a repeating unit represented by the formula (1) to a ring-closing reaction by heat or chemical means, or a polyimide having a repeating unit represented by the formula (2). It is done.
- Ar represents an aryl group.
- Polyamideimide and polyamideimide precursor Polyamideimide is not limited to its structure and molecular weight, and known ones can be used.
- the polyamideimide may have a functional group capable of condensing such as a carboxy group in the side chain or a functional group that promotes a crosslinking reaction or the like during firing.
- a soluble polyamideimide that is soluble in the solvent to be used is preferable.
- Polyamideimide is usually (i) a resin obtained by reacting an acid having a carboxyl group and an acid anhydride group in one molecule such as trimellitic anhydride and diisocyanate, (ii) trimellitic anhydride chloride, etc.
- a resin obtained by imidizing a precursor polymer (polyamideimide precursor) obtained by reacting a reactive derivative of the above acid with a diamine can be used without any particular limitation.
- trimellitic anhydride halides such as trimellitic anhydride and trimellitic anhydride chloride, trimellitic anhydride ester, and the like.
- Examples of the arbitrary diamine include the diamines exemplified in the description of the polyamic acid described above, and diaminopyridine compounds can also be used.
- the arbitrary diisocyanate is not particularly limited, and examples thereof include diisocyanate compounds corresponding to the arbitrary diamines, and specific examples thereof include metaphenylene diisocyanate, p-phenylene diisocyanate, o-tolidine diisocyanate, and p-phenylene.
- imidation in the method (ii) may be either thermal imidization or chemical imidization.
- chemical imidization a method of immersing an unfired composite film formed using a composition for producing a porous film containing a polyamideimide precursor in acetic anhydride or a mixed solvent of acetic anhydride and isoquinoline is used. Can do.
- the polyamideimide precursor can also be said to be a polyimide precursor in terms of a precursor before imidization.
- the polyamideimide to be contained in the varnish (1) a polymer obtained by reacting an acid such as trimellitic anhydride with diisocyanate, and (2) a reactive derivative of the above acid such as trimellitic anhydride and diamine. It may be a polymer obtained by imidizing a precursor polymer obtained by the reaction.
- the “polyamideimide precursor” means a polymer (precursor polymer) before imidization.
- Each of the polyamideimide and the polyamideimide precursor may be used alone or in combination of two or more.
- each of the said polymer, raw material monomer, and oligomer may be used individually by 1 type, and may be used in combination of 2 or more type.
- the polyethersulfone contained in the varnish can be appropriately selected according to the use of the porous membrane to be produced, and may be hydrophilic or hydrophobic. Further, it may be an aliphatic polyether sulfone or an aromatic polyether sulfone.
- the weight average molecular weight is, for example, 5000 to 1,000,000, preferably 10,000 to 300,000.
- the material of the fine particles is not particularly limited as long as it is insoluble in the solvent contained in the varnish and can be removed from the resin-fine particle composite film later.
- inorganic materials include metal oxides such as silica (silicon dioxide), titanium oxide, and alumina (Al 2 O 3 ), and organic materials include high molecular weight olefins (polypropylene, polyethylene, etc.), polystyrene, epoxy resins, and cellulose.
- Organic polymer fine particles such as polyvinyl alcohol, polyvinyl butyral, polyester, and polyether. The fine particles may be used alone or in combination of two or more.
- the fine particles include colloidal silica.
- colloidal silica when monodispersed spherical silica particles are selected, it is preferable because uniform pores can be formed.
- the solvent is not particularly limited as long as it can dissolve the resin component contained in the varnish and does not dissolve the fine particles, and those exemplified as the solvent used for the reaction between the tetracarboxylic dianhydride and the diamine. Can be mentioned.
- Examples of the solvent for incorporating polyethersulfone into the varnish include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, N, N Nitrogen-containing polar solvents such as diethylformamide, N-methylcaprolactam, N, N, N ′, N′-tetramethylurea, diphenylsulfone, dimethylsulfone, dimethylsulfoxide, benzophenone, tetrahydrothiophene-1,1-dioxide And polar solvents such as 1,3-dimethyl-2-imidazolidinone.
- a solvent may be used independently and may be used in combination of 2 or more type.
- a dispersant For the purpose of uniformly dispersing the fine particles in the varnish, a dispersant may be further added together with the fine particles.
- the resin component and the fine particles can be mixed more uniformly, and furthermore, the fine particles in the formed or formed film can be uniformly distributed.
- a dispersing agent it becomes easy to improve the drying property of a varnish, and it becomes easy to improve the peelability from the board
- the dispersing agent is not particularly limited, and known ones can be used.
- Anionic surfactants such as nate salt, isopropyl phosphate, polyoxyethylene alkyl ether phosphate salt, polyoxyethylene allyl phenyl ether phosphate salt; oleylamine acetate, lauryl pyridinium chloride, cetyl pyridinium chloride, lauryl trimethyl ammonium chloride, stearyl trimethyl ammonium chloride , Behenyltrimethylammonium chloride, did
- the content of the dispersant in the varnish is, for example, preferably from 0.01 to 5% by mass, more preferably from 0.05 to 1% by mass, based on the fine particles, from the viewpoint of film formability, and 0 Still more preferably, it is 1 to 0.5% by mass.
- a method for producing a porous film includes: an unfired composite film forming step for forming an unfired composite film using the varnish described above; and a firing step for firing the unfired composite film to obtain a resin-fine particle composite film And a fine particle removal step of removing fine particles from the resin-fine particle composite film.
- the unfired composite film is formed using the varnish described above.
- the unfired composite film may be directly formed on the substrate, or may be formed on a lower layer film different from the unfired composite film.
- an upper layer film different from the unfired composite film may be further formed on the upper layer.
- the method of providing the lower layer film on the substrate also forms an unfired composite film using the aforementioned varnish, and then forms an upper layer film different from the unfired composite film on the upper layer.
- the method is also included in the method for forming the unfired composite film on the substrate.
- the resin component contained in the varnish is a polyamic acid or polyamideimide precursor and a material that does not require a baking step is used for the upper layer film
- the upper layer film is formed on the resin-fine particle composite film after baking. It may be formed.
- the unfired composite film is formed, for example, by applying the varnish described above on the substrate or the lower layer film, and drying at 0 to 100 ° C., preferably 10 to 100 ° C. under normal pressure or vacuum. can do.
- the substrate include a PET film, a SUS substrate, and a glass substrate.
- the lower layer film for example, it contains a resin composed of polyamic acid, polyimide, polyamideimide precursor, polyamideimide and polyethersulfone, fine particles, and a solvent, and the content of the fine particles is as described above.
- the lower unfired composite film may be formed on the substrate.
- the content of the fine particles is more than 40% by volume, the particles are uniformly dispersed.
- the content of the fine particles is 81% by volume or less, the particles are dispersed without agglomeration.
- the pores can be formed uniformly in the membrane. Further, when the content of the fine particles is within the above range, when the lower unfired composite film is formed on the substrate, the release property after the film formation is improved even if the release layer is not provided on the substrate in advance. Easy to secure.
- the fine particles used for the lower (or upper) film-forming varnish and the fine particles used for the varnish described above may be the same or different from each other.
- the fine particles used in the lower (or upper) film forming varnish have a smaller or the same particle size distribution index as the fine particles used in the varnish described above.
- the fine particles used in the lower layer (or upper layer) film-forming varnish preferably have the same or less true sphericity than the fine particles used in the varnish described above.
- the average particle diameter of the fine particles used in the lower layer (or upper layer) film-forming varnish is preferably 5 to 1000 nm, more preferably 10 to 600 nm.
- the content of fine particles in the varnish for forming a lower layer (or upper layer) may be more or less than that of the varnish described above.
- Suitable examples of components such as a resin component, fine particles, and a solvent contained in the lower layer (or upper layer) film-forming varnish are the same as those of the aforementioned varnish.
- the varnish for forming a lower layer (or upper layer) can be prepared by the same method as that for the varnish described above.
- the lower unfired composite film is formed, for example, by applying the lower film forming varnish on a substrate and drying at 0 to 100 ° C., preferably 10 to 100 ° C. under normal pressure or vacuum. be able to.
- the film forming conditions for the upper unfired composite film are the same.
- the lower layer (or upper layer) film examples include a film made of a fiber material such as a cellulose resin, a nonwoven fabric (for example, a polyimide nonwoven fabric (fiber diameter is about 50 nm to about 3000 nm, for example)). And a polyimide film.
- the unfired composite film or a laminated film of the unfired composite film and the lower layer (or upper layer) film is fired to enter a firing step for obtaining a resin-fine particle composite film.
- the unfired composite film or the lower unfired composite film is formed on the substrate, it may be fired as it is, or before entering the firing step, the unfired composite film or the unfired composite film and the lower unfired film.
- the laminated film with the fired composite film may be peeled off from the substrate.
- the lower layer (or upper layer) film is a lower layer (or upper layer) unfired composite film formed using a lower layer (or upper layer) film-forming varnish, and the lower layer (or upper layer) film-forming varnish.
- the composition is the same as that of the varnish used for forming the unfired composite film, the laminated film of the unfired composite film and the lower layer (or upper layer) film is substantially one layer (single layer). is there.
- a substrate provided with a release layer in advance is used to further enhance the peelability of the film. You can also When a release layer is provided on the substrate in advance, a release agent is applied on the substrate and dried or baked before application of the composition for producing a porous film.
- a release agent such as alkyl phosphate ammonium salt, fluorine-based or silicone can be used without particular limitation.
- a cleaning process for cleaning the unfired composite film peeled from the substrate or the laminated film of the unfired composite film and the lower unfired composite film using an organic solvent may be introduced.
- the release layer forming step and the cleaning step can be omitted.
- the underlayer film is also fired together with the unfired composite film in the firing step.
- the firing temperature in the firing step is preferably 120 to 450 ° C., more preferably 150 to 400 ° C., although it varies depending on the structure of the unfired composite film and the lower layer film and the presence or absence of a condensing agent. Further, when an organic material is used for the fine particles, it is necessary to set the temperature to be lower than the thermal decomposition temperature. When the resin component contained in the varnish is polyamic acid, it is preferable to complete imidization in the firing step.
- the firing conditions are, for example, a method in which the temperature is raised from room temperature to 400 ° C. in 3 hours and then held at 400 ° C. for 20 minutes, or the temperature is gradually raised from room temperature to 400 ° C. in increments of 50 ° C. (holding 20 minutes for each step) And a stepwise drying-thermal imidization method such as a final holding at 400 ° C. for 20 minutes can also be used.
- a method is adopted in which the end of the unfired composite film is fixed to a SUS mold or the like to prevent deformation. You can also.
- the film thickness of the completed resin-fine particle composite film can be obtained by measuring and averaging the thickness of a plurality of locations with a micrometer, for example. What average film thickness is preferable depends on the use of the porous film, but for example, when used for a separator or the like, it is preferably 5 to 500 ⁇ m, more preferably 10 to 100 ⁇ m, 15 More preferably, it is ⁇ 30 ⁇ m. When used for a filter or the like, the thickness is preferably 5 to 500 ⁇ m, more preferably 10 to 300 ⁇ m, and still more preferably 20 to 150 ⁇ m.
- silica is used as the material of the fine particles
- An organic material can also be selected as the material of the fine particles. Any organic material can be used without particular limitation as long as it decomposes at a lower temperature than the resin contained in the resin-fine particle composite film.
- resin fine particles made of a linear polymer or a known depolymerizable polymer can be mentioned.
- a normal linear polymer is a polymer in which a polymer molecular chain is randomly cleaved during thermal decomposition
- a depolymerizable polymer is a polymer in which the polymer is decomposed into monomers during thermal decomposition. All of them disappear from the resin-fine particle composite film by decomposing to low molecular weight substances or CO 2 .
- the decomposition temperature of the resin fine particles used is preferably 200 to 320 ° C., more preferably 230 to 260 ° C.
- the decomposition temperature is 200 ° C. or higher, film formation can be performed even when a high boiling point solvent is used in the composition for producing a porous membrane, and the range of selection of the baking conditions for polyimide is widened. If the decomposition temperature is less than 320 ° C., only the resin fine particles can be lost without causing thermal damage to the polyimide.
- the total film thickness of the porous film is not particularly limited, but for example, when used for a separator or the like, it is preferably 5 to 500 ⁇ m, more preferably 10 to 100 ⁇ m, and 15 to 30 ⁇ m. More preferably. When used for a filter or the like, the thickness is preferably 5 to 500 ⁇ m, more preferably 10 to 300 ⁇ m, and still more preferably 20 to 150 ⁇ m.
- the film thickness can be obtained by measuring and averaging the thickness at a plurality of locations with a micrometer or the like, for example, as in the measurement of the resin-fine particle composite film.
- the ratio in the thickness direction of the region formed by each composition for producing a porous membrane may be appropriately set according to the use of the porous membrane.
- the ratio in the thickness direction of each region ((I) :( II)) is, for example, 1:99 to 99: 1, preferably 5:95 to 95: 5. .
- the thickness of each layer can be calculated by observing a plurality of locations on the cross section of the porous membrane with a scanning electron microscope (SEM) or the like and averaging them.
- SEM scanning electron microscope
- the method for producing a porous membrane includes a resin removal step of removing at least a part of the resin portion of the resin-particle composite membrane before the fine particle removal step, or removing at least a portion of the porous membrane after the fine particle removal step. You may have. By removing at least a part of the resin part of the resin-particulate composite film before the fine particle removal process, when the fine particles are removed and pores are formed in the subsequent fine particle removal process, at least a part of the resin part is removed. It is possible to improve the open area ratio of the porous film of the final product as compared with those not removed.
- the porosity of the porous film of the final product can be improved as compared with the case where at least a part of the porous film is not removed. It becomes possible.
- the step of removing at least a part of the resin part or the step of removing at least a part of the porous film may be performed by a normal chemical etching method, a physical removal method, or a combination thereof. it can.
- Examples of the chemical etching method include treatment with a chemical etching solution such as an inorganic alkali solution or an organic alkali solution.
- a chemical etching solution such as an inorganic alkali solution or an organic alkali solution.
- Inorganic alkaline solutions are preferred.
- the inorganic alkaline solution include, for example, a hydrazine solution containing hydrazine hydrate and ethylenediamine, a solution of an alkali metal hydroxide such as potassium hydroxide, sodium hydroxide, sodium carbonate, sodium silicate, and sodium metasilicate, an ammonia solution, and a hydroxide.
- Examples thereof include an etchant containing alkali, hydrazine and 1,3-dimethyl-2-imidazolidinone as main components.
- Organic alkaline solutions include primary amines such as ethylamine and n-propylamine; secondary amines such as diethylamine and di-n-butylamine; tertiary amines such as triethylamine and methyldiethylamine; dimethylethanolamine And alcohol amines such as triethanolamine; quaternary ammonium salts such as tetramethylammonium hydroxide and tetraethylammonium hydroxide; and alkaline solutions such as cyclic amines such as pyrrole and pihelidine.
- primary amines such as ethylamine and n-propylamine
- secondary amines such as diethylamine and di-n-butylamine
- tertiary amines such as triethylamine and methyldiethylamine
- dimethylethanolamine And alcohol amines such as triethanolamine
- quaternary ammonium salts such as tetra
- the solvent of each solution pure water and alcohols can be selected as appropriate. Moreover, what added a suitable amount of surfactant can also be used.
- the alkali concentration is, for example, 0.01 to 20% by mass.
- a physical method for example, plasma (oxygen, argon, etc.), dry etching by corona discharge, etc., an abrasive (eg, alumina (hardness 9), etc.) is dispersed in a liquid, and this is applied to the film surface.
- plasma oxygen, argon, etc.
- an abrasive eg, alumina (hardness 9), etc.
- a method of surface treatment by irradiating at a speed of 30 to 100 m / s can be used.
- the above-described method is preferable because it can be applied to any resin removal step before or after the fine particle removal step.
- a mount film for example, a polyester film such as a PET film
- a method of peeling the porous film from the mount film can also be adopted. Due to the surface tension or electrostatic adhesion force of the liquid, the porous film is peeled off from the mount film with only the surface layer of the porous film remaining on the mount film.
- a composition for producing a porous membrane was prepared. After applying the composition for producing a porous film on a substrate, the solvent was removed by heating at 90 ° C. for 300 seconds to form a coating film having a thickness of about 40 ⁇ m. The surface of the formed coating film was observed with a scanning electron microscope (SEM). The obtained SEM image is shown in FIG.
- FIG. 2B shows an observation image at a higher magnification than that in FIG.
- Example 2 In the same manner as in Comparative Example 1, dispersion and kneading were carried out to prepare a composition for producing a porous membrane (the mass ratio of polyamic acid: silica in the final composition was 30:70), and then a bead mill (zirconia beads 0.3 mm). After processing at a peripheral speed of 11, 1 hour (Asada Iron Works Co., Ltd. PICO MILL). A composition for producing a porous membrane was obtained. After coating on the substrate, the solvent was removed by heating at 90 ° C. for 300 seconds to form a coating film. When observed by SEM, a good coating film similar to Example 1 was obtained.
- Example 1 and Example 2 in which a good coating film (unfired composite film) was obtained were imidized by heat treatment (baking) at 380 ° C. for 15 minutes to obtain a resin-fine particle composite film.
- Example 2 Air permeability
- the liquid permeability at a filtration pressure of 0.1 MPa or 0.08 MPa was evaluated for water, propylene glycol monomethyl ether acetate, isopropanol, and a photoresist composition.
- the liquid permeability was evaluated by passing the test liquid through the surface of a circular porous membrane having a diameter of 47 mm set in the housing. The evaluation results of liquid permeability are shown in Table 1 below.
- -Composition for producing porous membrane for lower layer membrane 1 prepared in the same manner as in Example 2.
- -Composition for producing porous film for upper layer film 1 prepared according to Reference Example 1 below.
- -Composition 2 for producing porous membrane for upper layer membrane Prepared according to Reference Example 2 below.
- Reference Example 2 A composition for producing a porous membrane was prepared in the same manner as in Reference Example 1 except that the mass ratio of polyamic acid: silica in the final composition was 20:80 (the approximate volume ratio was 28:72). .
- the composition 1 for producing a porous film for a lower layer film was formed with an applicator so as to have a film thickness of about 2 ⁇ m to form a lower layer film.
- the porous membrane production composition 1 for the upper layer film was formed on the lower layer film using an applicator, pre-baked at 90 ° C. for 5 minutes, and the lower layer film containing fine particles having different average particle diameters, An unsintered composite film having a film thickness of about 25 ⁇ m composed of the upper layer film was obtained.
- the unfired composite film was immersed in water for 3 minutes and then pressed through two rolls.
- the roll holding pressure was 3.0 kg / cm 2
- the roll temperature was 80 ° C.
- the moving speed of the unfired composite film was 0.5 m / min.
- the unfired composite film peeled from the substrate after the press treatment was subjected to heat treatment at 400 ° C. for 15 minutes to form a polyimide-fine particle composite film having a film thickness of about 25 ⁇ m.
- the polyimide-fine particle composite film is immersed in a 10% HF solution for 10 minutes to remove the fine particles contained in the film, followed by washing with water and drying.
- the lower layer film and the upper layer film having different average pore diameters, respectively.
- a porous membrane having a thickness of about 25 ⁇ m was obtained.
- the air permeability measured in the same manner as described above was 299 seconds.
- Example 4 A lower layer film and an upper layer having different average pore diameters in the same manner as in Example 3 except that the composition 1 for producing a porous film for a lower layer film was changed to the composition 2 for producing a porous film for a lower layer film. A porous film having a film thickness of about 24 ⁇ m was obtained. The air permeability measured in the same manner as described above was 92 seconds.
- Example 5 A slurry (3-b) comprising the following components was dispersed by a three roll mill. Next, while adding dimethylacetamide to a solid content concentration of 42% by mass, the slurry (3-b) was dispersed and mixed by a rotating / revolving mixer (trade name: manufactured by Shintaro Awatori Shinki Co., Ltd.). A composition for producing a porous membrane was prepared by performing smelting twice. After coating the composition for producing a porous film on a substrate, the solvent was removed by heating at 90 ° C. for 300 seconds to form a coated film.
- the obtained coating film (resin-fine particle composite film) was immersed in a 10% HF solution for 10 minutes to remove fine particles contained in the film. After removal of the fine particles, washing with water and drying were performed to obtain a porous film having a film thickness of about 40 ⁇ m. The surface of the obtained porous film was observed with a scanning electron microscope (SEM).
- SEM scanning electron microscope
- the obtained SEM image is shown in FIG. From FIG. 3, in the porous membrane formed using the composition for producing a porous membrane of Example 5 prepared using a three-roll mill that disperses by shearing force and compressive force, the average particle size of 100 nm is small silica. It can be seen that even the fine particles are uniformly dispersed and made porous.
- a composition for producing a porous membrane was prepared by dispersing and kneading (the mass ratio of polyethersulfone: silica in the final composition was 20:80).
- Solvent 80 parts by mass of dimethylacetamide
- Fine particles 80 parts by mass of silica (average particle size 100 nm) (including 0.5% by mass of dispersant relative to silica)
- ⁇ Ingredients of varnish (1-d)> Resin: 67 parts by mass of polyethersulfone (dimethylacetamide 30% by mass solution) (solid content of polyethersulfone: 20 parts by mass)
- the film After coating the composition for producing a porous film on a substrate, the film was heated at 90 ° C. for 300 seconds to remove the solvent to form a coated film, and then a polyethersulfone having a film thickness of about 40 ⁇ m was formed in the same manner as in Example 5. A porous membrane was obtained. The surface of the formed porous film was observed with a scanning electron microscope (SEM). The obtained SEM image is shown in FIG. From FIG. 4, in the composition for producing a porous membrane prepared using a rotating / revolving mixer that disperses by centrifugal force, silica fine particles agglomerate partially, and the resin membrane is not uniform even when porous. It can be seen that sex remains.
- SEM scanning electron microscope
Abstract
Description
微粒子と溶剤とを含むスラリー(1)を調製する工程、
ポリアミド酸、ポリイミド、ポリアミドイミド前駆体、ポリアミドイミド及びポリエーテルスルホンよりなる群から選択される少なくとも1つの樹脂成分と溶剤とを含むワニス(1)を調製する工程、
スラリー(1)とワニス(1)とを混練しスラリー(2)を調製する工程、及び
スラリー(2)をせん断力と、圧縮力又は衝撃力とにより分散させる工程、を含む多孔質膜製造用組成物の製造方法である。
多孔質膜の製造方法は、微粒子と、樹脂成分とを含有する多孔質膜製造用組成物(以下、単にワニスと略称することがある)の調製工程において、微粒子を含むスラリーをせん断力と、圧縮力又は衝撃力とにより分散させる分散工程を含む。樹脂成分としては、ポリアミド酸、ポリイミド、ポリアミドイミド前駆体、ポリアミドイミド及びポリエーテルスルホンよりなる群から選択される1種以上が使用される。
以下、多孔質膜製造用組成物の調製工程について説明する。
前述の通り、多孔質膜製造用組成物の調製工程は、微粒子を含むスラリーをせん断力と、圧縮力又は衝撃力とにより分散させる分散工程を含む。
上記分散工程において、せん断力と圧縮力とによりスラリーを分散させる装置としては、例えば三本ロールミル等の高せん断分散装置が好ましく用いられる。
せん断力と衝撃力とによりスラリー中の微粒子を分散させる装置しては、ビーズミル等の装置が好ましく用いられる。
一方、プラネタリーミキサー等の装置は、平均粒子径が比較的大きな微粒子を分散させるには十分であるが、せん断力のみで混錬するため、平均粒子径が200nm以下である粒径の小さい微粒子を分散させるには不十分である。
せん断力と、圧縮力又は衝撃力とによりスラリー中の微粒子を分散させることにより、平均粒子径が小さな微粒子を分散させる場合でも、分散された微粒子の再凝集を抑制しつつ、微粒子を均一に分散させることができる。
なお、多孔質膜内に形成される、微粒子に由来する孔部のサイズは、微粒子の平均粒子径と同一であるか近い。このため、多孔質膜をフィルターとして用いる場合の流体の透過性等の点から、微粒子の平均粒子径は、5nm以上が好ましく、10nm以上がより好ましい。
また、微粒子は、真球率が高く、粒径分布指数の小さいものが好ましい。これらの条件を備えた微粒子は、ワニス中での分散性に優れ、互いに凝集しない状態で使用することができる。
[第一の実施形態]
多孔質膜製造用組成物の調製工程は、微粒子と溶剤とを含むスラリー(1)を調製する工程、ポリアミド酸、ポリイミド、ポリアミドイミド前駆体、ポリアミドイミド及びポリエーテルスルホンよりなる群から選択される少なくとも1つの樹脂成分と溶剤とを含むワニス(1)を調製する工程、スラリー(1)とワニス(1)とを混練しスラリー(2)を調製する工程、及びスラリー(2)をせん断力と、圧縮力又は衝撃力とにより分散させる工程を有してよい。
スラリー(2)をせん断力と圧縮力とにより分散させる場合、スラリー(2)の固形分濃度は、特に限定されないが例えば、10質量%以上であり、30質量%以上であることが好ましく、40質量%以上がより好ましく、上限は例えば60質量%以下である。
スラリー(2)をせん断力と衝撃力とにより分散させる場合、スラリー(2)の固形分濃度は、特に限定されないが例えば、1質量%以上であり、5質量%以上であることが好ましく、10質量%以上がより好ましく、上限は例えば60質量%以下である。
また、上記調製工程は、スラリー(2)をせん断力と、圧縮力又は衝撃力とにより分散させる工程の前工程として、スラリー(2)をプラネタリーミキサーで混錬する等、せん断力のみにより混錬する工程を有してよい。
多孔質膜製造用組成物の調製工程は、微粒子と溶剤とを含むスラリー(1)を調製する工程、スラリー(1)をせん断力と、圧縮力又は衝撃力とにより分散させる工程、ポリアミド酸、ポリイミド、ポリアミドイミド前駆体、ポリアミドイミド及びポリエーテルスルホンよりなる群から選択される少なくとも1つの樹脂成分と、溶剤とを含むワニス(1)を調製する工程、及び分散工程を経たスラリー(1)とワニス(1)とを混練する工程を有してよい。
スラリー(1)をせん断力と圧縮力とにより分散させる場合、スラリー(2)の固形分濃度は、特に限定されないが例えば、10質量%以上であり、30質量%以上であることが好ましく、40質量%以上がより好ましく、上限は例えば90質量%以下である。
スラリー(1)をせん断力と衝撃力とにより分散させる場合、スラリー(2)の固形分濃度は、特に限定されないが例えば、1質量%以上であり、5質量%以上であることが好ましく、10質量%以上がより好ましく、上限は例えば90質量%以下である。
調製工程は、分散工程を経たスラリー(1)とワニス(1)とを混練する工程の前工程として、スラリー(1)とワニス(1)とを自転・公転ミキサーで混錬する等、遠心力によりスラリーを混錬する工程を有してよい。
分散工程を経たスラリー(1)とワニス(1)とを混練する際には、微粒子の再凝集が起きやすい。このことから、調製工程は、分散工程を経たスラリー(1)とワニス(1)とを混練する工程の後工程として、再度、せん断力と、圧縮力又は衝撃力とにより分散させる工程を有してよい。
多孔質膜製造用組成物の調製工程は、例えば、微粒子と、ポリアミド酸、ポリイミド、ポリアミドイミド前駆体、ポリアミドイミド及びポリエーテルスルホンよりなる群から選択される少なくとも1つの樹脂成分とを含有するスラリー(3)を調製し、スラリー(3)をせん断力、及び圧縮力又は衝撃力により分散させる工程、及び分散工程を経たスラリー(3)に溶剤を添加し、スラリー(3)の粘度を下げる粘度調製工程を有してよい。
粘度調製工程では、スラリー(3)の粘度が5Pa・s以下に調製されるのが好ましい。第三の実施形態において、分散工程時のスラリー(3)は、粘度が高い状態、例えば、5Pa・sを超えているため、せん断力、及び圧縮力又は衝撃力により微粒子がより効率よく分散されやすくなると考えられる。
スラリー(3)をせん断力と圧縮力とにより分散させる場合、スラリー(3)の固形分濃度は、特に限定されないが例えば、10質量%以上であり、30質量%以上であることが好ましく、40質量%以上がより好ましく、上限は例えば60質量%以下である。
スラリー(3)をせん断力と衝撃力とにより分散させる場合、スラリー(2)の固形分濃度は、特に限定されないが例えば、1質量%以上であり、5質量%以上であることが好ましく、10質量%以上がより好ましく、上限は例えば60質量%以下である。
以下、多孔質膜製造用組成物(ワニス)の調製工程で使用される、ワニスの必須又は任意の成分について説明する。
ワニスは、樹脂成分として、ポリアミド酸、ポリイミド、ポリアミドイミド前駆体、ポリアミドイミド及びポリエーテルスルホンよりなる群から選択される少なくとも1つを含有する。以下、ポリアミド酸と、ポリイミドと、ポリアミドイミド及びポリアミドイミド前駆体と、ポリエーテルスルホンとについて順に説明する。
ポリアミド酸としては、任意のテトラカルボン酸二無水物とジアミンとを重合して得られる生成物が、特に限定されることなく使用できる。テトラカルボン酸二無水物及びジアミンの使用量は特に限定されないが、テトラカルボン酸二無水物1モルに対して、ジアミンを0.50~1.50モル用いるのが好ましく、0.60~1.30モル用いるのがより好ましく、0.70~1.20モル用いるのが特に好ましい。
これらの溶剤は1種を単独で用いてもよく、2種以上を組み合わせて用いてもよい。溶剤の使用量に特に制限はないが、生成するポリアミド酸の含有量が5~50質量%とするのが望ましい。
ポリアミド酸は、1種を単独で用いてもよく、2種以上を組み合わせて用いてもよい。
ポリイミドは、その構造や分子量が限定されることはなく、公知のものが使用できる。ポリイミドについて、側鎖にカルボキシ基等の縮合可能な官能基又は焼成時に架橋反応等を促進させる官能基を有していてもよい。また、多孔質膜製造用組成物が溶剤を含有する場合、使用する溶剤に溶解可能な可溶性ポリイミドが好ましい。
ポリイミド及びそのモノマーの各々は、1種を単独で用いてもよく、2種以上を組み合わせて用いてもよい。
ポリアミドイミドは、その構造や分子量に限定されることなく、公知のものが使用できる。ポリアミドイミドについて、側鎖にカルボキシ基等の縮合可能な官能基又は焼成時に架橋反応等を促進させる官能基を有していてもよい。また、多孔質膜製造用組成物が溶剤を含有する場合、使用する溶剤に溶解可能な可溶性ポリアミドイミドが好ましい。
ポリアミドイミド及びポリアミドイミド前駆体の各々は、1種を単独で用いてもよく、2種以上を組み合わせて用いてもよい。また、ポリアミドイミドについて、上記ポリマー、原料モノマー、及びオリゴマーの各々は、1種を単独で用いてもよく、2種以上を組み合わせて用いてもよい。
ワニスに含有させるポリエーテルスルホンとしては、製造する多孔質膜の用途に応じて適宜選択することができ、親水性でも疎水性であってもよい。また脂肪族ポリエーテルスルホンであっても芳香族ポリエーテルスルホンであってもよい。質量平均分子量は、例えば、5000~1,000,000であり、好ましくは10,000~300,000である。
微粒子の材質は、ワニスに含まれる溶剤に不溶で、後に樹脂-微粒子複合膜から除去可能なであれば、特に限定されることなく公知の材質を採用可能である。例えば、無機材料としては、シリカ(二酸化珪素)、酸化チタン、アルミナ(Al2O3)等の金属酸化物、有機材料としては、高分子量オレフィン(ポリプロピレン,ポリエチレン等)、ポリスチレン、エポキシ樹脂、セルロース、ポリビニルアルコール、ポリビニルブチラール、ポリエステル、ポリエーテル等の有機高分子微粒子が挙げられる。微粒子は、単独で用いてもよく、2種以上を組み合わせて用いてもよい。
溶剤としては、ワニスに含まれる樹脂成分を溶解することができ、微粒子を溶解しないものであれば、特に限定されず、テトラカルボン酸二無水物とジアミンとの反応に用いる溶剤として例示したものが挙げられる。また、ワニスにポリエーテルスルホンを含有させる場合の溶媒としては、例えば、N-メチル-2-ピロリドン、N,N-ジメチルアセトアミド、N,N-ジエチルアセトアミド、N,N-ジメチルホルムアミド、N,N-ジエチルホルムアミド、N-メチルカプロラクタム、N,N,N’,N’-テトラメチルウレア等の含窒素極性溶剤の他、ジフェニルスルホン、ジメチルスルホン、ジメチルスルホキシド、ベンゾフェノン、テトラヒドロチオフェン-1,1-ジオキシド、1,3-ジメチル-2-イミダゾリジノン等の極性溶媒が挙げられる。溶剤は、単独で用いてもよく、2種以上を組み合わせて用いてもよい。
ワニス中の微粒子を均一に分散させることを目的に、微粒子とともに更に分散剤を添加してもよい。分散剤を添加することにより、樹脂成分と微粒子とを一層均一に混合でき、更には、成形又は成膜した膜中の微粒子を均一に分布させることができる。その結果、最終的に得られる多孔質膜の表面に稠密な開口を設け、かつ、表裏面を効率よく連通させることが可能となり、多孔質膜の透気度が向上する。更に、分散剤を添加することにより、ワニスの乾燥性が向上しやすくなり、また、形成された未焼成複合膜の基板等からの剥離性が向上しやすくなる。
多孔質膜の製造方法は、上述したワニスを用いて、未焼成複合膜を成膜する未焼成複合膜成膜工程と、上記未焼成複合膜を焼成して樹脂-微粒子複合膜を得る焼成工程と、上記樹脂-微粒子複合膜から微粒子を取り除く微粒子除去工程と、を有する。
以下、未焼成複合膜の成膜方法について説明する。未焼成複合膜成膜工程においては、前述のワニスを用いて、未焼成複合膜を成膜する。その際、未焼成複合膜は、基板上に直接成膜してもよいし、上記未焼成複合膜とは異なる下層膜上に成膜してもよい。また、前述のワニス(多孔質膜製造用組成物)を用いて、未焼成複合膜を成膜した後に、更に上層に上記未焼成複合膜とは異なる上層膜を成膜してもよい。なお、本出願において、基板上に下層膜を設ける方法も、前述のワニスを用いて、未焼成複合膜を成膜した後に、更に上層に上記未焼成複合膜とは異なる上層膜を成膜する方法も、基板上に未焼成複合膜を形成する方法に含める。ただし、前述のワニスに含まれる樹脂成分が、ポリアミド酸又はポリアミドイミド前駆体であって、上層膜に焼成工程不要の材料を用いる場合は、焼成後の樹脂-微粒子複合膜に対し、上層膜を形成してもよい。
未焼成複合膜は、例えば、基板上又は上記下層膜上に、前述のワニスを塗布し、常圧又は真空下で0~100℃、好ましくは常圧10~100℃で乾燥することにより、形成することができる。
基板としては、例えば、PETフィルム、SUS基板、ガラス基板等が挙げられる。
ワニスに含まれる樹脂成分が、ポリアミド酸又はポリアミドイミド前駆体の場合、上記未焼成複合膜に加熱による後処理(焼成)を行って、ポリイミド及び/又はポリアミドイミドからなる樹脂と、微粒子と、からなる複合膜(樹脂-微粒子複合膜)とする。なお、ワニスに含まれる樹脂成分が、ポリイミド、ポリアミドイミド又はポリエーテルスルホンである場合は、焼成工程を省いてもよい。上記未焼成複合膜成膜工程において、上記未焼成複合膜とは異なる下層膜上に上記未焼成複合膜を成膜した場合には、焼成工程において、上記未焼成複合膜とともに上記下層膜も焼成する。焼成工程における焼成温度は、未焼成複合膜及び下層膜の構造や縮合剤の有無によっても異なるが、120~450℃であることが好ましく、更に好ましくは150~400℃である。また、微粒子に、有機材料を使用するときは、その熱分解温度よりも低い温度に設定する必要がある。ワニスに含まれる樹脂成分が、ポリアミド酸の場合、焼成工程においてはイミド化を完結させることが好ましい。
樹脂-微粒子複合膜から、微粒子を適切な方法を選択して除去することにより、多孔質膜を再現性よく製造することができる。
多孔質膜の製造方法は、微粒子除去工程前に、樹脂-微粒子複合膜の樹脂部分の少なくとも一部を除去するか、又は、微粒子除去工程後に多孔質膜の少なくとも一部を除去する樹脂除去工程を有していてもよい。微粒子除去工程前に、樹脂-微粒子複合膜の樹脂部分の少なくとも一部を除去することにより、続く微粒子除去工程で微粒子が取り除かれ空孔が形成された場合に、上記樹脂部分の少なくとも一部を除去しないものに比べて、最終製品の多孔質膜の開孔率を向上させることが可能となる。また、微粒子除去工程後に多孔質膜の少なくとも一部を除去することにより、上記多孔質膜の少なくとも一部を除去しないものに比べて、最終製品の多孔質膜の開孔率を向上させることが可能となる。
下記成分からなるスラリー(3-a)を3本ロールミルにて分散させた後、ジメチルアセトアミドとガンマブチロラクトンを固形分濃度が30質量%(最終溶剤組成の質量比はジメチルアセトアミド:ガンマブチロラクトン=90:10)となるように加え多孔質膜製造用組成物を調製した。多孔質膜製造用組成物を基板上に塗布した後、90℃で300秒間加熱して溶剤を除去して膜厚約40μmの塗布膜を形成した。形成された塗布膜の表面を走査型電子顕微鏡(SEM)により観察した。得られたSEM画像を図1に示す。
<スラリー(3-a)の成分>
樹脂:ポリアミド酸(ジメチルアセトアミド20質量%溶液)30質量部(ポリアミド酸の固形分量)
微粒子:シリカ(平均粒子径150nm)70質量部(シリカに対し、0.5質量%の分散剤を含む)
下記成分からなるスラリー(1-a)とポリアミド酸の濃度が14.3質量%であるワニス(1-a)とを自転・公転ミキサー(商品名:あわとり練太郎(株)シンキー製)にて、ジメチルアセトアミドとガンマブチロラクトンとを最終組成物の固形分濃度が30質量%(最終溶剤組成の質量比はジメチルアセトアミド:ガンマブチロラクトン=90:10)となるように加えながら、分散・混錬し、多孔質膜製造用組成物を調製した(最終組成物におけるポリアミド酸:シリカの質量比は30:70)。多孔質膜製造用組成物を基板上に塗布した後、90℃で300秒間加熱して溶剤を除去して塗布膜を形成した。形成された塗布膜の表面を走査型電子顕微鏡(SEM)により観察した。得られたSEM画像を図2(a)、及び図2(b)に示す。図2(b)に示されるのは、図2(a)よりも高倍率での観察像である。
<スラリー(1-a)の成分>
溶剤:ジメチルアセトアミド50質量部
微粒子:シリカ(平均粒子径150nm)50質量部(シリカに対し、0.5質量%の分散剤を含む)
<ワニス(1-a)の成分>
樹脂:ポリアミド酸(ジメチルアセトアミド20質量%溶液)
溶剤:ジメチルアセトアミド
比較例1と同様に、分散・混錬し、多孔質膜製造用組成物を調製した(最終組成物におけるポリアミド酸:シリカの質量比は30:70)後、更にビーズミル(ジルコニアビーズ0.3mm、周速11、1時間(浅田鉄工(株) PICO MILL))にて、処理した後。多孔質膜製造用組成物を得た。基板上に塗布した後、90℃で300秒間加熱して溶剤を除去して塗布膜を形成した。SEMにより観察したところ、実施例1と同様の良好な塗布膜が得られた。
これに対し、図2(a)(b)から、遠心力により分散を行う自転・公転ミキサーを用いて調製した多孔質膜製造用組成物においては、シリカ微粒子の凝集が部分的に観察されることが分かる。
良好な塗布膜(未焼成複合膜)が得られた実施例1及び実施例2について、380℃で15分間加熱処理(焼成)することにより、イミド化させ、樹脂-微粒子複合膜を得た。
得られた各樹脂-微粒子複合膜について、10%HF溶液中に10分間浸漬することで、膜中に含まれる微粒子を除去した。微粒子の除去後、水洗及び乾燥を行い、多孔質膜を得た。得られた膜をSEMにより観察したところ、実施例2の多孔質膜の方が、表面の開口率が高かった。
実施例1及び実施例2で得られた多孔質膜について、各々を5cm角に切り出して、透気度測定用のサンプルとした。ガーレー式デンソメーター(東洋精機製)を用いて、JIS P 8117に準じて、100mlの空気が上記サンプルを通過する時間を測定した。その結果、実施例1よりも実施例2の方が約100秒早いことが確認できた。実施例2の方が、分散状態が良好な多孔質膜製造用組成物が得られたため、多孔質膜の透気度が早くなったものと考えられる。
通液性の評価結果を以下表1に記す。
・下層膜用の多孔質膜製造用組成物1:実施例2と同様に調整した。
・上層膜用の多孔質膜製造用組成物1:下記参考例1により調整した。
・上層膜用の多孔質膜製造用組成物2:下記参考例2により調整した。
下記成分からなるスラリー(1-a)とポリアミド酸の濃度が14.3質量%であるワニス(1-b)とを自転・公転ミキサー(商品名:あわとり練太郎(株)シンキー製)にて、ジメチルアセトアミドとガンマブチロラクトンとを最終組成物の固形分濃度が30質量%(最終溶剤組成の質量比はジメチルアセトアミド:ガンマブチロラクトン=90:10)となるように加えながら、分散・混錬し、多孔質膜製造用組成物を調製した(最終組成物におけるポリアミド酸:シリカの質量比は30:70、(およその体積比は40:60))。
<スラリー(1-a)の成分>
溶剤:ジメチルアセトアミド50質量部
微粒子:シリカ(平均粒子径700nm)50質量部(シリカに対し、0.5質量%の分<ワニス(1-b)の成分>
樹脂:ポリアミド酸(ジメチルアセトアミド20質量%溶液)
溶剤:ジメチルアセトアミド
散剤を含む)
最終組成物におけるポリアミド酸:シリカの質量比が20:80(およその体積比は28:72)となるようにした他は、参考例1と同様にして多孔質膜製造用組成物を調製した。
[実施例3]
PETフィルム上に、下層膜用の多孔質膜製造用組成物1を、アプリケーターで膜厚約2μmとなるように成膜し、下層膜を形成した。続いて、上層膜用の多孔質膜製造用組成物1を、前記下層膜上にアプリケーターを用い成膜し、90℃で5分間プリベークして、それぞれ平均粒子径の異なる微粒子を含む下層膜と上層膜からなる膜厚約25μmの未焼成複合膜を得た。未焼成複合膜を水に3分間浸漬した後に2本のロール間に通してプレスした。その際、ロール抑え圧は3.0kg/cm2、ロール温度は80℃、未焼成複合膜の移動速度は0.5m/minであった。プレス処理後の基体から剥離された未焼成複合膜について、400℃で15分間熱処理を施し、膜厚約25μmのポリイミド-微粒子複合膜を形成した。次いで、ポリイミド-微粒子複合膜を、10%HF溶液中に10分間浸漬することで、膜中に含まれる微粒子を除去した後水洗及び乾燥を行い、それぞれ異なる平均空孔径を有する下層膜と上層膜からなる膜厚約25μmの多孔質膜を得た。上記と同様にして測定した透気度は、299秒であった。
下層膜用の多孔質膜製造用組成物1を下層膜用の多孔質膜製造用組成物2に変えた他は、実施例3と同様にして、それぞれ異なる平均空孔径を有する下層膜と上層膜からなる膜厚約24μmの多孔質膜を得た。上記と同様にして測定した透気度は、92秒であった。
下記成分からなるスラリー(3-b)を3本ロールミルにて分散させた。次いで、ジメチルアセトアミドを固形分濃度が42質量%となるように加えながら、スラリー(3-b)を、自転・公転ミキサー(商品名:あわとり練太郎(株)シンキー製)による、分散・混錬を2回行って、多孔質膜製造用組成物を調製した。
多孔質膜製造用組成物を基板上に塗布した後、90℃で300秒間加熱して溶剤を除去して塗布膜を形成した。
<スラリー(3-b)の成分>
樹脂:ポリエーテルスルホン(ジメチルアセトアミド35質量%溶液)57質量部(ポリエーテルスルホンの固形分量:20質量部)
微粒子:シリカ(平均粒子径100nm)80質量部(シリカに対し、0.5質量%の分散剤を含む)
得られた多孔質膜の表面を走査型電子顕微鏡(SEM)により観察した。得られたSEM画像を図3に示す。
図3から、せん断力と圧縮力により分散を行う3本ロールミルを用いて調製した実施例5の多孔質膜製造用組成物を用いて形成された多孔質膜では、平均粒子径100nmと小さいシリカ微粒子でも、均一に分散されて多孔化されていることが分かる。
下記成分をホモジナイザーにより混練して得たスラリー(1-c)と、下記成分を自転・公転ミキサー(商品名:あわとり練太郎(株)シンキー製)により混練して得た、ワニス(1-d)とを、自転・公転ミキサー(商品名:あわとり練太郎(株)シンキー製)にて、ジメチルアセトアミドとガンマブチロラクトンとを最終組成物の固形分濃度が42質量%となるように加えながら、分散・混錬し、多孔質膜製造用組成物を調製した(最終組成物におけるポリエーテルスルホン:シリカの質量比は20:80)。
<スラリー(1-c)の成分>
溶剤:ジメチルアセトアミド80質量部
微粒子:シリカ(平均粒子径100nm)80質量部(シリカに対し、0.5質量%の分散剤を含む)
<ワニス(1-d)の成分>
樹脂:ポリエーテルスルホン(ジメチルアセトアミド30質量%溶液)67質量部(ポリエーテルスルホンの固形分量:20質量部)
図4から、遠心力により分散を行う自転・公転ミキサーを用いて調製した多孔質膜製造用組成物においては、シリカ微粒子の凝集が部分的に発生し、多孔化した際も樹脂膜の不均一性が残って観察されることが分かる。
Claims (7)
- 多孔質膜の製造方法であって、
微粒子と、ポリアミド酸、ポリイミド、ポリアミドイミド前駆体、ポリアミドイミド及びポリエーテルスルホンよりなる群から選択される少なくとも1つの樹脂成分とを含有する多孔質膜製造用組成物の調製工程を含み、
前記調製工程は、前記微粒子を含むスラリーをせん断力と、圧縮力又は衝撃力とにより分散させる分散工程を含む製造方法。 - 前記微粒子の平均粒子径が200nm以下である、請求項1記載の製造方法。
- 前記スラリー中の前記微粒子の含有量が、前記スラリーの質量の20質量%以上、90質量%以下である、請求項1又は2記載の製造方法。
- 前記微粒子が、無機微粒子である、請求項1~3のいずれか1項記載の製造方法。
- 更に、前記スラリーの粘度を5Pa・s以下に下げる工程を含む、請求項1~4のいずれか1項記載の製造方法。
- 更に、前記多孔質膜製造用組成物を用いて、未焼成複合膜を形成する未焼成複合膜形成工程と、
前記未焼成複合膜を焼成して樹脂-微粒子複合膜を得る焼成工程と、
前記樹脂-微粒子複合膜から微粒子を取り除く微粒子除去工程と、を含む、請求項1~5のいずれか1項記載の製造方法。 - 微粒子と、溶剤とを含むスラリー(1)を調製する工程、
ポリアミド酸、ポリイミド、ポリアミドイミド前駆体、ポリアミドイミド及びポリエーテルスルホンよりなる群から選択される少なくとも1つの樹脂成分と、溶剤とを含むワニス(1)を調製する工程、
前記スラリー(1)と、前記ワニス(1)とを混練しスラリー(2)を調製する工程、及び
前記スラリー(2)をせん断力と、圧縮力又は衝撃力とにより分散させる工程を含む
多孔質膜製造用組成物の製造方法。
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US20180244887A1 (en) | 2018-08-30 |
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