JP2008144039A - Fluid-permeable fine porous material and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid-permeable fine porous material having a novel substrate composition and structure and is suitable for a separator for a secondary battery etc., a filtering medium, a culture medium, a moisture-permeable material, etc. <P>SOLUTION: The fluid-permeable fine porous material made of a thermoplastic resin comprises 50-99 wt.% thermoplastic resin (A) used as a substrate and 1-50 wt.% in total of a pore-forming material (B) and an aperture-forming agent (C) which are mixed and dispersed therein. The porous material is formed by extending a fine porous material-forming precursor composition molded product so that boundaries between the thermoplastic resin (A) used as the substrate and the pore-forming material (B) and the aperture-forming agent (C) are at least partially separated to produce pores (P) and apertures (I). The porous material has a group of large pores (P) having an average pore diameter of 0.5-100 μm and a group of smaller apertures (I) having an average aperture diameter of 0.01-30 μm on at least part of a porous wall part of the pore (P) and has an air permeability of ≤1,000 (sec/100 cc×25 μm thickness) and a porosity of 30-90%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is typified by a lithium ion battery, a lithium metal battery, a lithium polymer battery, or a nickel metal hydride battery, which is used as a base material as it is or in combination with an electrolyte, an electrically conductive object, etc. as a base material. For separators such as electrochemical separators (separators), electrolytic capacitors, and electric double layer capacitors used in various secondary batteries, other secondary batteries, and primary batteries, etc., and in gases and liquids It is represented by a filter medium for filtering and removing a substance having a predetermined shape and property, a specific blood cell in blood, or a base material for filtering or adsorbing and removing a specific substance or the same component in blood. Precision / active microfiltration membranes, carriers for culturing various types of cells for medical use (including materials that are biodegraded and disappear after culture), and culturing various types of cells for medical use to effectively extract specific active ingredients Used as a filter material, a carrier that adsorbs specific substances (including materials that biodegrade and disappear after culture), a carrier that slowly releases specific adsorbed or mixed substances, electronic components, etc. It is a base material for polishing such as polishing a predetermined part for circuit setting, anti-condensation breathable film material for construction using moisture permeability, clothing material, sanitary materials such as diapers and sanitary products, breathable moisture permeability It is a special fluid-permeable porous material that is advantageously optimized and used for packaging films that prevent the passage of bacteria, dust, etc., light-reflecting films with high whiteness, and printing paper materials.

Conventionally, the most common polyolefin (PO) resin as a thermoplastic resin, for example, a microporous body made of crystalline high-density polyethylene (HDPE), crystalline polypropylene (PP), etc., with a thickness of about 20 to 100 μm, There are known microporous films having communication holes with a diameter of about 0.01 μm to 5 μm that are communicated from one surface to the other surface in the thickness direction uniformly over the entire surface in the vertical direction of the thickness. Degree (second / 100 cc · 25 μm thickness) has gas permeability of about 50 to 1000, while having water permeability resistance, such as many applications that require such performance, for example, ion permeation in electrolyte And is used for applications such as batteries as an insulating diaphragm between electrodes.
Conventionally, as a method for producing such a porous film, for example, the following production methods (1) to (4) are known. (1) The above highly crystalline HDPE is heated and dissolved in a large amount of a plasticizer (volume of 45 to 80 vol%) to form a gel, then extruded into a film or sheet, cooled, and the resin is After solidifying and crystallizing and phase-separating with the plasticizer, the plasticizer is extracted with a solvent to form microporous nuclei, and then the so-called phase is produced by growing and expanding the micropores by stretching. Separation aperture method.

In this method, when the amount of the plasticizer is relatively small (for example, 40 to 55 vol%), the hole size is too small (for example, 0.001 to 0.1 μm), although the uniformity of the communication holes is excellent. Average diameter), permeation resistance is large, there is a limit to increasing the thickness, and clogging is likely to occur on the surface, which limits the application.
On the other hand, when the amount of the plasticizer is relatively large (for example, 50 to 80 vol%), the phase-separated plasticizer may be aggregated to have a large particle size, and large void-like nonuniform pores are generated. In addition, a large amount of dangerous (for safety and hygiene) solvents must be used, and it is difficult to produce a thick product at high speed due to extraction efficiency.
Next, (2) when the crystalline resin is melted and extruded into a sheet, it is flow oriented in the longitudinal (flow) direction at the optimum temperature and draw ratio for each of the resins (some molecules are aligned in the flow direction). Then, in the next step, spend enough time under the optimum conditions for each resin (for example, increase the temperature stepwise for about 5 to 30 minutes) to grow crystals and clarify the interface Next, cold stretching is performed with a strong force in the uniaxial (longitudinal) direction to break the crystal interface to create micropores, and then uniaxially stretching to hot at higher temperatures to grow the opening part to some extent. There is a method (for example, see Patent Document 1), a so-called stretch opening method.

In this method, there are problems in productivity (production speed, yield, for example, many pieces of film during production, uneven thickness dispersion, etc., quality such as inhibition of flatness of winding shape by gage band), etc. . Further, when biaxial stretching is performed by this method, the strength balance in the vertical / horizontal direction is poor, and there is a great drawback that it is easy to tear in the vertical direction.
In addition, there is (3) a method in which a soluble filler is added to form a film on a film, and then the filler is eluted to make it microporous (for example, see Patent Document 2). However, this method is brittle and can be stretched. In addition, the strength is low, the pores are uneven and large, the air permeability is extremely large, and a dense porous body cannot be formed.
Further, there is known a method (4) in which a composition containing a large amount of filler (for example, 40 to 60% by weight) is directly blown from a die to form a continuous microporous material. This method has a problem that the pores are clogged with filler, the strength is low, the filler is crushed, the pore size varies, and the fluid permeability is poor.

Japanese Patent Publication No.55-32531 JP 58-29839 A

  The present invention has an unprecedented structure and characteristics that can be obtained at once (including multi-layered products obtained) by stretching a molded body made of a specific composition without extracting it with a solvent or the like. A porous body adapted for various uses, having a relatively large aperture and a plurality of smaller apertures on the aperture wall, and a single-layer shape having the properties of being stretched and oriented as a whole, or Furthermore, the present invention provides a novel fluid-permeable porous body in which another kind of resin layer is combined or a layer having a different structure is combined.

That is, the present invention
1. From 50 to 99% by weight of the base material thermoplastic resin (A) to be a continuous phase, and 1 to 50% by weight of the total amount of the pore-opening material (B) and the opening agent (C) mixed and dispersed therein. By stretching the molded body of the microporous body forming precursor composition, at least a part of the interface between the thermoplastic resin (A) of the base material and the pore opening material (B) and the opening agent (C) is peeled off. A fine fluid-permeable porous body of thermoplastic resin formed by the formation of the opening (P) and the opening (I), the porous body having a large opening having an average pore diameter of 0.5 to 100 μm. A hole (P) group and a smaller opening (I) group having an average opening diameter of 0.01 to 30 μm in at least a part of the opening wall portion of the opening (P), and air permeability Is 1000 (sec / 100 cc · 25 μm thickness) or less, and the porosity is 30 to 90%. Porous material.

2. By further stretching the microfluidic porous material described in 1 above, at least a part of at least one part of the aperture (P) group and the aperture (I) group is collapsed or continuously formed. The part has a non-woven fibrillated structure, has an air permeability of 0.05 to 500 (sec / 100 cc · 25 μm thickness), and a porosity of 30 to 90%. Fluid porous body.
3. The thermoplastic resin (A) is 55 to 98% by weight, the pore-opening material (B) is 2 to 45% by weight, and the opening agent (C) is 0 to 15% by weight. Or the fine fluid-permeable porous body of 2.
4). 1 above, characterized in that the thermoplastic resin (A) comprises 60 to 94% by weight, the pore-opening material (B) 5 to 40% by weight, and the opening agent (C) 1 to 10% by weight. The fine fluid-permeable porous material according to any one of -3.

5. The thermoplastic resin (A) is a polyolefin resin, an aliphatic polyester resin, a polyester resin containing an aromatic component, an α-olefin and carbon monoxide copolymer, a polyamide resin, a fluorine resin, or a polysulfone resin. 5. The microfluidic porous material according to any one of 1 to 4 above, comprising at least one selected.
6). Any one of 1 to 5 above, wherein the pore-opening material (B) comprises at least one resin selected from polyphenylene ether resins, styrene resins, and saturated hydrocarbon resins having a ring and ball softening point of 150 ° C. or higher. The microfluidic porous material described in 1.
7). Opening material (B) is a composition of polyphenylene ether resin and styrene resin, composition of polyphenylene ether resin and saturated hydrocarbon resin, polyphenylene ether resin, styrene resin and saturated hydrocarbon resin 7. The fine fluid-permeable porous body according to any one of 1 to 6 above, comprising one kind of composition selected from the compositions.

8). The porous body has at least two 0.01-30 μm pores on a large aperture (P) group having an average pore diameter of 0.5-100 μm and at least one aperture wall portion of the aperture (P). A smaller aperture (I) group having an average aperture diameter, an average diameter ratio (P / I) of at least 2, and an air permeability of 0.5 to 500 (sec / 100 cc · 25 μm thickness) 8. The microfluidic porous material according to any one of 1 to 7 above, which has a hybrid structure.
9. The porous material is one type selected from a film shape having a thickness of 2 to 200 μm, a sheet shape having a thickness of 200 to 5000 μm, a thread shape having a diameter of 2 to 5000 μm, and a hollow fiber shape having a diameter of 2 to 5000 μm. The fine fluid-permeable porous material according to any one of -8.

10. The porous body is a multilayer composed of a combination of one or more layers selected from layers having different compositions, layers having different structures, layers having different characteristics, or the like. 10. The microfluidic porous material according to any one of 9 above.
11. 11. The fine fluid permeability as described in any one of 1 to 10 above, wherein the porous body has a porosity of 30 to 80% and an air permeability of 0.5 to 500 (sec / 100 cc · 25 μm thickness). Porous body.
12 11. The microfluidic permeability as described in any one of 1 to 10 above, wherein the porous body has a porosity of 40 to 85% and an air permeability of 0.1 to 80 (sec / 100 cc · 25 μm thickness). Porous body.

13. 13. The method for producing a microfluidic porous body according to any one of 1 to 12 above, wherein the microporous body-forming precursor layer based on at least one thermoplastic resin (A), and at least A stretching auxiliary layer (S) of a composition which is mainly composed of a thermoplastic resin different from the resin constituting the precursor layer and does not become a fluid-permeable structure by stretching, is then co-stretched. A method for producing a microfluidic porous material, wherein the layer is peeled and removed.
14 A multilayer microfluidic porous body comprising two or more layers, wherein at least one layer is the microfluidic porous body described in any one of 1 to 12 above, and the other layers are A microfluidic porous body characterized by a porous structure having characteristics different from those of the above.

  A microfluidic porous body having a novel base material composition and structure, which is a separator for lithium secondary batteries, nickel hydride secondary batteries, etc., a filter medium for removing attachments, a culture body effective for culturing cells and the like, and water A porous body suitable for a moisture-permeable material for health care or clothing that does not pass through but effectively allows water vapor to pass therethrough can be provided.

Below, each structure of this invention is demonstrated in detail.
(1) Thermoplastic resin (A)
The base material thermoplastic resin (A) (hereinafter sometimes simply referred to as base material resin (A)), which is the continuous phase of the porous body of the present invention, is a polyolefin resin, an aliphatic polyester resin, an aromatic resin. It is at least one selected from known resins such as polyester resins containing components, α-olefin and carbon monoxide copolymers, polyamide resins, fluorine resins, polysulfone resins, and the like.

More specifically, the polyolefin-based resin is, for example, low-density polyethylene, medium-density polyethylene, high-density polyethylene, a so-called linear-type polymer polymerized with these single-site catalysts, or other monomers. Polymerized polyethylene resins, for example, homopolymers, random copolymers copolymerized with other α-olefins, and polypropylene resins, including those polymerized with these catalysts, and other α-olefins. Polymerized crystalline polybutene-1 resin, 4-methylpentene-1 resin, and copolymers selected from these monomers, and other monomers containing polar groups (for example, vinyl acetate, acrylic Copolymers with acids and derivatives thereof, methacrylic acid and derivatives thereof (high-pressure method, low-pressure method, radical method system or catalyst) There are polymers selected from at least one kind selected from special single-site catalysts and special metallocene catalysts, which are not inactivated by these polar groups, and mixed compositions thereof.
In addition, there are α-olefin and carbon monoxide copolymers, copolymers of α-olefins and cyclic olefins, and hydrogenated resins thereof.

Aliphatic polyester resins are polylactic acid resins, polyglycolic acid resins, poly-3-hydroxybutyric acid resins, poly α-hydroxyisobutyric acid resins, or at least one monomer used in these. There are resins in which at least one monomer selected from other species is copolymerized in an amount of 25 mol% or less.
Polyester resins containing aromatic components are polyethylene terephthalate resins, polybutylene terephthalate resins, polyethylene naphthalate resins, polycyclohexanedimethanol terephthalate resins, and free copolymers of monomers used in these resins. Etc.

The polyamide-based resin is an aliphatic dicarboxylic acid and the same diamine, or nylon-6, the same -66, the same 6-66, the same 6-10, the same 12, or an acid component, or an amine. A polyamide-based resin having an aromatic component in one of the components.
In addition to being represented by polyvinylidene fluoride resin, the fluororesin is a copolymer in which at least a part of hydrogen of other polyolefin molecular structure that is crystalline and can be extruded is halogen-substituted, or a polar functional group As an active fluorine-based resin containing a carboxyl group, a sulfone group, an amino group, and the like.
In addition, it is selected from an ethylene-vinyl alcohol copolymer, a polycarbonate resin, other engineering plastic resins, and the like.

(2) Opening material (B)
When the pore opening material (B) is a thermoplastic resin, a desired amount of the compatibilizing material (agent) or the like is added to the base resin (A) in a desired shape by adding a small amount as needed. Raw material resin consisting of a base resin (A) which is selected from those dispersed or having a size distribution, or cross-linked resin particles, inorganic particles and the like, and containing the pore-opening material (B) Is extruded to form a desired shape of the forming raw material, and when this is stretched, at least a part of the interface between the base resin (A) and the aperture material (B) is peeled off, and at least a large opening is formed. It has the function and action of forming the hole (P) group.

When a thermoplastic resin is used as the pore-opening material (B), it is generally a material that is not so compatible with the base resin (A). For example, even in a viscoelastic damping coefficient curve, the characteristic peak is the base resin ( A) is not molecularly dispersed and identical to A), but preferably the form at the time of kneading and dispersing is basically left as it is even after extrusion stretching (for example, the average diameter is 0.05 μm or more). In some cases, even if it is compatibilized once during kneading, it is uniformly phase-separated by post-processing, and is present in, for example, a state close to granularity at the time of stretching, forming the above large aperture (P) group Anything that can be done.

  In addition, the pore-opening material (B) is harder than the base resin (A) itself or the base resin composition modified by adding other materials to the base resin (A) under the stretching temperature condition, or more Those that are difficult to deform, those that easily peel off even when deformed, those that are substantially cross-linked and difficult to flow even if deformed, those that have a recovery force against deformation, and those that peel easily Those modified by adding other additives to are preferably selected. As a specific scale, for example, when the pore-opening material (B) is a resin component, it is measured under the stretching temperature condition according to the measuring method of the softening point (Vicat softening point, ring and ball method softening point, various surface hardnesses, etc.). Difference in any of the measured values) or deformation stress (for example, any of tensile elastic modulus, compression elastic modulus, deformation stress, etc. at 10% deformation) is 10% or more than that of the base resin (A) A high or harder pore-opening material (B) is preferable in that stretching stress concentrates and it is easy to open. As for the softening point, even if the softening point of the amorphous part of the resin component is low, if it is crystalline and has a high crystalline melting point, the property after crystallization may be used.

  Specifically, when the base resin (A) is a polyolefin-based resin, the pore-opening material (B) has the above-mentioned polyamide-based resin, ethylene vinyl alcohol copolymer, aliphatic polyester-based resin, aromatic Polyester-based resin containing a group component, resin having a cyclic saturated hydrocarbon component, ethylene carbon monoxide copolymer (including hydrogenated modified product), polycarbonate resin (including copolymer modified product), halogen-substituted carbonized carbon Hydrogen resin, styrene resin, styrene and α-methylstyrene copolymer, copolymer of styrene and aliphatic carboxylic acid derivative monomer, high impact polystyrene, syndiotactic styrene resin, polyphenylene ether resin (modified) At least one kind of resin selected from (including copolymers), etc., or modified by freely compounding the resin as a raw material Selected from fat composition, or the like. These resins are preferably relatively low polymer resins from the viewpoint of dispersion control, but dispersion may be controlled by using a relatively high polymer in combination with a compatibilizing agent (material).

In addition, the diameter is controlled by crosslinked fine particles such as silicone resin (modified product). The base resin (A) has good mixing and dispersibility and is out of the above viewpoint. Even soft materials are being extruded. In addition, a material that is difficult to be deformed, such as cutting, merging, and deforming, and that has a good releasability from the base resin at the interface, can effectively form the above large aperture (P) group during stretching, It can be set as an aperture material (B).
In addition, cross-linked fine particles made of a relatively hard resin from the above viewpoint are preferable because they are not easily deformed during extrusion in the same manner as described above, and stress is easily concentrated even under stretching conditions.
In addition, fine particles with a controlled shape of a thermosetting resin system may be used.
In addition to these, silica, calcium carbonate, carbon particles, and those subjected to surface treatment thereof may be used as inorganic substances.

The dispersion shape of the pore opening material (B) in the base resin (A) may be arbitrary as long as a desired hole is obtained, but generally, the closer to a spherical shape, the more stretchable and the uniformity of the hole. It is preferable from the viewpoint of fluid permeability and strength, but there is no special limitation. The complicated shape with unevenness, thread shape, dispersion diameter and shape are non-uniform and large variation, pore uniformity, membrane strength In many cases, it is not preferable.
About the shape (ratio of major axis / minor axis) of these aperture materials (B), the average of the major axis / minor axis in each orthogonal direction was further averaged in three directions by the three-dimensional projection method. In this case, the ratio of the major axis / minor axis in the orthogonal direction is preferably within 10 times, more preferably within 5 times, and the ratio of the maximum / minimum average value in each of the above directions (3 directions). Is within 10 times, more preferably within 5 times as well.

In addition, the pore opening material (B) is used in combination with a base resin (A) having a relatively large diameter for forming a large opening (P) and a material having a smaller diameter. Thus, it may further serve as an opening agent (C) for forming a small opening (I) on the opening wall of the large opening (P).
In that case, as the pore opening material (B), the same kind of material or other kinds of materials may be used, and in this case, a material having a relatively large diameter (referred to as X) is smaller. The ratio of the average dispersion diameter in any one of the above methods (X / Y) of those having a diameter (referred to as Y) is at least 5, preferably at least 10, and more preferably at least 20.
More preferably, the area of the overlapping portion of the aperture distribution curves measured by any one of the above methods is preferably less than 20%. More preferably, it is less than 10%, More preferably, it is less than 2%. This is because there is a problem in the uniformity, strength, stretchability, etc. of the distribution of each of the large apertures (P) and the small apertures (I) in the aperture wall.

(3) Opening agent (C)
The opening agent (C) is added in a small amount, and is itself present in the pore wall portion during stretching, and is microdispersed or microphase-separated with a diameter smaller than the pore opening material (B). A) is present in a finely dispersed manner at the microcrystalline interface, crystal defect portion, or amorphous portion of the base material, and the pore-opening material (B) is first peeled off from the base resin (A) during stretching. A large aperture (P) is formed, and at the same time as stretching, a thin film forming an aperture wall begins to be formed, and when the stretching stress becomes easy to concentrate, the opening agent (C) acts, and at least the aperture wall portion A large number of small openings (I) are formed on the surface, and as a result, fluid permeability is exhibited.

Further, it is often preferable that the opening agent (C) also has an effect of facilitating the peeling of the interface of the opening material (B) that generates the large opening (P).
Specific examples of the opening agent (C) include fatty alcohols, aliphatic alcohol esters, polyhydric alcohol esters, alkali metal salts as aliphatic alcohols, carboxylic acids, or derivatives thereof having a relatively long carbon chain. Alkaline earth metal salts, etc., preferably stearic acid amide, erucic acid amide, fatty acid glycerin ester (including partially esterified products such as mono, di, and tri), polyglycerin ester, sorbitan ester, sorbitol ester, etc. Yes. Also, silicone oils (including alkyl type, modified products such as phenyl, phenol, ether, carbinol, amino, mercapto, epoxy, carboxyl, higher fatty acid ester, fluorine), oligomers of the above resins, It may be selected from saturated hydrocarbons such as liquid paraffin and paraffin wax.

(4) Use amount of base resin (A), aperture material (B), and opening agent (C) The usage amount of base resin (A), aperture material (B), and opening agent (C) is The base resin (A) is preferably 50 to 99% by weight of the thermoplastic resin (A), and the total amount of the opening material (B) and the opening agent (C) is more preferably 1 to 50% by weight. Consists of 55 to 98% by weight of the thermoplastic resin (A), 2 to 45% by weight of the aperture material (B), and 0 to 15% by weight of the opening agent (C), more preferably The thermoplastic resin (A) is 60 to 94% by weight, the pore-opening material (B) is 5 to 40% by weight, and the opening agent (C) is 1 to 10% by weight.
Furthermore, for the purpose of improving the stretchability during production, the tensile strength, tear strength, pore size distribution, etc. of the resulting microporous film, the thermoplastic resin (A), the pore opening material (B), and the opening agent (C) With respect to the whole, preferably within a range of 0.05 to 30% by weight, using known modifiers, additives, processing aids such as crystal nucleating agents, compatibilizers, soft resins, elastomers, etc. There is no problem.

(5) Porous structure / shape of microfluidic porous body The porous structure of the microfluidic porous body of the present invention (hereinafter sometimes simply referred to as a porous body) has an average pore diameter of 0.5 to 100 μm, A large aperture (P) group that is preferably 0.7 to 50 μm, more preferably 1 to 30 μm, and an aperture (I) in an aperture wall portion of at least one part of the aperture is one aperture ( The number of the apertures is at least a plurality, preferably 5 or more, more preferably 10 or more with respect to P), and the average aperture diameter (of the above-mentioned aperture wall portion) is 0.01 to 30 μm, preferably A smaller aperture (I) group that is 0.03 to 20 μm, more preferably 0.05 to 10 μm, and preferably its ratio of average diameters (P / I) is at least 2, preferably at least 5, more A porous structure, preferably at least 10 It is.

  In addition, the average opening (opening) diameter of the opening (P) (opening (I)) is obtained by observing the surface of the porous body with a scanning electron microscope (SEM), and the diameter of 10 opening (opening) portions. It was obtained by averaging (minor axis in the case of an ellipse).

  The porosity of the microfluidic porous material of the present invention is 30 to 90%, preferably 30 to 80%, more preferably 40 to 85%.

The air permeability of the porous body of the present invention is 1000 (sec / 100 cc · 25 μm thickness) or less, preferably 0.05 to 1000 (sec / 100 cc · 25 μm thickness), more preferably 0.00, depending on the specific porous structure. A low air permeability (high fluid permeability) of 1 to 700 (sec / 100 cc · 25 μm thickness), more preferably 0.5 to 500 (sec / 100 cc · 25 μm thickness) can be achieved.
Further, as described above, the porous body is further stretched and fibrillated, so that it is preferably 0.05 to 1000 (sec / 100 cc · 25 μm thickness), more preferably 0.05 to 500 (sec / 100 cc · 25 μm thickness). More preferably, the air permeability (higher fluid permeability) of 0.1 to 100 (sec / 100 cc · 25 μm thickness) can be obtained.

The porous body of the present invention is stretched and oriented in at least one axial direction, and its maximum shrinkage is at least 30%, preferably at least 40% in the stretch direction, and its maximum shrinkage stress is at least 20 g / mm ² , preferably It is at least 50 g / mm ² , and in the case of a film or sheet, stretching in the biaxial direction is preferable in terms of strength and fluid permeability.
The shape of the porous body of the present invention is selected from a film shape of 2 to 200 μm, a sheet shape of 200 to 5000 μm thickness, a thread shape of 5 to 5000 μm diameter, and a hollow fiber shape of 5 to 5000 μm diameter according to the purpose. .
A more preferable porous body in each application of the present invention is a multilayer.
The reason for this is that when the properties required for the porous body are different from the properties required for the entire porous body and the properties required for the surface layer, such as a highly functional material, it is necessary to form the porous body in multiple layers. However, according to the preferred production method of the present invention, a multilayer porous body having different functions can be easily obtained.

Depending on the purpose, the multilayer porous body of the present invention has different layers even if the same base resin is used, or a layer made of a composition using different base resins, or a different structure. A multi-layer porous body composed of a combination of one or more layers selected from layers having different characteristics.
In addition, the porous body of the present invention may be formed in a multilayered form in which a porous body having a porous structure having a different characteristic from that of the present invention is combined depending on applications.
The preferred production method of the present invention is highly compatible with a production method for forming a porous body having a different porous structure, and a multilayer composite porous body having various functions can be easily obtained.

  Specifically, a preferred use of the porous body of the present invention is, for example, a separator for a lithium ion secondary battery. In this case, preferably in the form of three layers, the heat resistance derived from the surface layer function (temperature at which the dimension is shrunk by 5% in the stretching direction when heated in air) is at least 120 ° C, preferably at least 130 ° C, more preferably at least 140. C., more preferably at least 160.degree. C., and at the same time, the inner layer plugging temperature (referred to as the fuse temperature: mainly shrinks or flows in the thickness direction in the battery, and the porous structure is effectively plugged, resulting in high resistance or insulation. The temperature at which the electrochemical reaction between the electrodes in the battery is substantially stopped, the so-called electrically insulating state) is 140 ° C. or less, more preferably 120 ° C. or less, and even more preferably 110 ° C. or less. Most preferably, it is 100 ° C. or lower. The porous body of the present invention is characterized in that the heat resistance derived from the surface layer function and the closing temperature of the inner layer can be set more freely according to the purpose by freely selecting the resin.

In the hybrid structure of the porous body of the present invention, the small aperture (I) group is mainly quickly closed, and responds effectively to the safety of the battery (explosion prevention due to runaway reaction) by reacting to the thermal and time. In addition, the heat-resistant layer on the surface layer further shrinks to a high temperature or melts and flows, and prevents the electrode from short-circuiting and exploding, thereby contributing to more safety.
The next preferred use of the porous body of the present invention is a separator for a “nickel-hydrogen battery” as a secondary battery. This “nickel-hydrogen battery” is a battery that is advantageous in that it can take out a high output in a short time. This is achieved by using a low internal resistance aqueous electrolyte and a separator having a lower resistance performance corresponding thereto. There is a feature in that. Polypropylene nonwoven fabric is currently used, but in the future, the battery will be increased in capacity, and small, lightweight and safe batteries will be used for applications around electric vehicles that use electricity as the driving source, mounting in portable devices, The separator has the following problems. That is, if the thickness is reduced, the number of pinholes increases and there is a risk of shorting between the electrodes, and cushioning (buffering) against the expansion and contraction of the electrodes during charge / discharge is lost. Further, when trying to cope with this problem using thin fibers, there is a problem that it is difficult to make the separator thin for reasons such as difficulty in manufacturing and high price.

On the other hand, the need for electric vehicles, gasoline-powered hybrid vehicles, and fuel cells has recently been particularly raised due to the advancement of portable devices (responding to the increasing trend of electricity usage), environmental and material-saving problems. At present, there is a demand for an excellent separator that can be used in a battery that can increase the energy density for use in a hybrid electric vehicle or the like that can be efficiently charged and discharged.
The porous body of the present invention is an optimal porous body as a battery separator to be mounted on the hybrid electric vehicle or the like.

In other words, the porous body of the present invention can also reduce the electrical resistance, which is the main cause of the internal resistance of the battery, as described above (after), and even in the thin region, the high absorbency and high content of the electrolysis solution. Liquidity, moderate cushioning that can follow changes in thickness when using electrodes, and smooth mobility to the counter electrode of the generated gas due to low air permeability (easy to pass gas) The prevention of explosion) is also ensured, and the conventional phase separation method porous membrane (using a resin and a large amount of plasticizer, which is manufactured by extracting the plasticizer after phase separation, for example, the aperture is about 0.04 μm, In addition, it is used as a separator that exhibits excellent performance that cannot be achieved with a high air permeability of about 300 to 600 (sec / 100 cc · 25 μm thickness) consisting of a group of pores having a single aperture distribution, Or has the above three layers of heat resistance and safety occlusion function The layer structure is utilized in the form of such (elaborating the embodiment).
The porous body of the present invention exerts the above-mentioned excellent function is composed of its large opening (P) and a small opening (I) provided in an opening wall portion of at least one part of the opening (P). Derived from a porous structure. Since the small opening (I) portion, which is the rate-determining part of the specific porous structure, is mainly on the opening wall of the large opening (P) in the thickness direction of the porous body, the total equivalent thickness is small (the reason is In other words, the electrical resistance is lowered by a large amount due to the presence of a large opening (P), and further, the portion where the current density is different when energized due to the fluid passage portion due to the opening (P) / opening (I). Therefore, when the porous body of the present invention is used in a lithium ion battery, lithium metal dendrites (needle crystals) hardly grow perpendicular to the thickness direction during charging, and a short-circuit phenomenon also occurs. hard. Further, the above-described specific opening (P) / opening (I) structure is excellent in absorption retention and cushioning properties of the electrolysis solution.

(6) Method for Producing Microfluidic Porous Material The method for producing a microfluidic porous material of the present invention comprises a thermoplastic resin (A) as a base material, the pore-opening material (B), and an opening agent (C). If necessary, a small amount of the compatibilizer (D) for controlling the dispersion diameter and dispersion shape of (B) is mixed well with a biaxial extruder or the like, and is a single layer or a multilayer, and optionally a stretching auxiliary layer Extrude the laminated body added with a die, and then rapidly cool and solidify it into a desired molded body (raw material), and then the molded body at 15 ° C. or higher and below the melting point of the thermoplastic resin (A) of the substrate. Or at a temperature of 50 ° C. or less added to the Vicat softening point and at least in one direction at an area stretch ratio of 1.1 times to 70 times, thereby extending the thermoplastic resin (A) of the substrate and the opening. At least a part of the interface with the pore material (B) peels off to form a large pore (P) group, and the additive (C ) To form a small aperture (I) group in the aperture wall portion of at least a part of the aperture (P), and a hybrid having a pore distribution of two-phase aperture (P) / aperture (I) A manufacturing method for forming a fluid-permeable path of a mold.

As the stretching operation, uniaxial stretching, sequential biaxial stretching, and simultaneous biaxial stretching are appropriately employed as necessary.
These stretching operations may be performed in multiple stages. Even in this case, at 15 ° C. or higher and below the melting point of the thermoplastic resin (A) of the base material or below the temperature obtained by adding 50 ° C. to the Vicat softening point, the area stretch ratio is 1.1 times in at least one direction. Although it will not specifically limit if it is more than 70 times or less, It is preferable that the temperature difference of the extending | stretching start part in each stage is at least 5 degreeC or more. Further, the stretching start temperature is preferably increased by at least about 5 ° C. in the subsequent stages of the multistage.
The area stretch ratio is 1.1 to 70 times, preferably 1.5 to 50 times. Next, when the obtained microfluidic porous material is further stretched and fibrillated to form a nonwoven fabric, the stretching ratio is preferably 16 to 70 times, more preferably 25 to 60 times.
Further, when dimensional stability is particularly important, the temperature of the final drawing stage may be increased to give a heat setting effect, or a heat setting process may be added as the next process.

Below, the preferable example of the manufacturing method of the porous body of this invention is demonstrated.
To obtain a high-quality porous body (abbreviated as M layer) of the present invention, an auxiliary layer that is peeled and removed when the M layer is commercialized for the purpose of assisting processing (extrusion, stretching, other operations). (Abbreviated as S layer) is used.
More specifically, by using this S layer, it is possible to impart a uniform and high fluid orientation during extrusion, which was impossible with the M layer alone, and also solve the following problems.
That is, it becomes non-uniform and tears during the stretching process, the hole forming property is different in the thickness direction, the property is different in the thickness direction, the uniformity is not uniform in the width direction, and the bubble method is more severely conditioned by the condition. (Especially in the case of low temperature conditions or when applying a high degree of stretching in the transverse direction, in addition to the problem of puncture and non-uniformity, the air in the bubble cannot escape and cannot be sealed, and the stretching can be continued. Even in the case of a problem such as absence, a microporous film can be efficiently produced by using this S layer.

In addition, during processing or handling, the S layer can also serve to protect the M layer from scratches and contamination (bacteria, dirt, etc.).
Since this S layer is peeled and removed when the M layer is commercialized, basically a different type of resin from the M layer is selected. If the S layer adheres to the M layer, or if both layers enter each other, the opening on the surface of the M layer is affected, and the opening becomes non-uniform, and in extreme cases, a portion that does not open is created. However, it has been found that there is no influence on the opening of the surface of the M layer as long as it can be practically peeled off.
The resin (E) constituting the S layer is not particularly limited as long as it can improve the film formability and stretchability of the M layer and can be easily peeled off from the M layer later. A thermoplastic resin different from the thermoplastic resin (A) to be used is selected which does not become a fluid-permeable porous body at the time of stretching but easily peels after stretching.

Specifically, what is not necessarily the same as the type of resin constituting the adjacent M layer may be selected. In particular, it is preferable that one of a polyolefin resin, a polyamide resin, and a polyester resin be a main component. Among these, the polyolefin resin is mainly composed of a low density polyethylene resin, a polypropylene resin, a crystalline polybutene 1 resin, an ionomer resin or the like (50 vol% or more). Among these, a particularly preferred composition is, for example, a crystalline polybutene-1 resin, a composition in which the polybutene-1 resin is mixed with 30% by weight or less of a petroleum resin, or a polybutene-1 resin in a ratio of 10 in the total composition. A ternary composition mixed with ˜90% by weight, a composition obtained by mixing 5-30% by weight of a petroleum-based resin with a polypropylene-based resin, a copolymerized polyester-based resin, or
Hereinafter, from a resin composition comprising (E1), (E2) and (E3), a resin composition comprising (E1) and (E2), or a resin composition comprising (E2) and (E3), which will be described later. A resin composition selected from the group consisting of:

E1: Low density polyethylene (polymerized by high pressure method, metallocene catalyst, single site catalyst, etc., copolymerized α-olefin having 15 mol% or less, for example, α and C3-C12 α -Containing at least one olefinic monomer), or at least one monomer selected from vinyl ester monomers, aliphatic unsaturated monocarboxylic acids, monocarboxylic acid alkyl esters, and ethylene. A (co) polymer having at least one VSP (Vicat softening point) selected from a copolymer, an ethylene-styrene copolymer, or a derivative thereof having a temperature of 80 ° C. or higher, or a mixed composition thereof;
E2: a soft thermoplastic elastomer having a VSP of 80 ° C. or lower;
E3: at least one selected from a homopolymer of propylene, butene-1,4-methylpentene-1, HDPE and the like, or at least one selected from these monomers and ethylene or another α-olefin At least one copolymer selected from copolymers of these with monomers, or derivatives thereof;

The polybutene-1 is a high molecular weight polymer having a butene-1 content of 93 mol% or more and containing a copolymer with other monomers (for example, ethylene, propylene, C5 or more). Unlike liquid and waxy low molecular weight, MI (ASTM method D1238 (measured according to E conditions): hereinafter referred to as MI) 0.2 to 10 is preferable. A composition obtained by mixing polybutene-1 with a hydrogenated saturated hydrocarbon resin (preferably, the same resin containing at least part of a cyclic portion as one component of the structural unit) is also preferably used.
In addition, the thermoplastic resin (E) constituting the S layer has moderate peelability from the M layer, or at the same time, improves the adhesion during the process (particularly during stretching) (so that each layer does not fall apart). In order to make the opening of the surface of the porous body uniform and smooth, to prevent or leak the generation of static electricity at the time of peeling, it is preferable to contain various additives that can bleed to the interface with the M layer.

Examples of such additives include nonionic surfactants such as esters of fatty acids and polyhydric alcohols, polyoxyethylene alkyl ethers, or higher alcohols, fatty acid amides, waxes, and fluorine-based surfactants. -Silicon-based additives and other additives that meet specific purposes with special functions may be mentioned, and these may be selected according to the purpose.
Of these, preferably the liquid component is mainly composed of at least 50 ° C., more preferably, the M layer and the S layer are coextruded and stretched, and then these quickly bleed to the interface with the M layer,
As described above, a material is selected that can easily peel off both layers, and at the same time maintain appropriate adhesion between the two layers, and can also prevent static electricity and prevent leakage. Such an additive effectively bleeds out without aging, and makes it possible to peel off and wind up the auxiliary layer and the microporous film without breaking at high speed even on-line.

In some cases, the above bleedable additive may be applied to the M layer or both layers. The additive amount of these additives is 0.2 to 5% by weight. If the amount is less than 0.2% by weight, the effect of facilitating peeling may not be sufficiently obtained. If the amount exceeds 5% by weight, appropriate adhesion between the two layers cannot be maintained, and peeling may occur during the process (particularly stretching).
When the preferable whole layer constitution combining the M layer and the S layer is exemplified, it is sufficient that at least both layers are included in one layer. For example, M / S, M / S / M, S / M / S, M / S / M / S / M, etc. are mentioned. When the M layer is a single layer, an entire layer configuration including a plurality of M layers may be economically desirable from the viewpoint of productivity.
Further, as already described, each of the M layer and the S layer itself may have a multilayer structure, and when priority is given to high performance and high quality of the microporous film, preferably S / M1 / M2, S / M1 / M2 / S, S / M1 / M2 / M1, S / M1 / M2 / M1 / S, M1 / M2 / M1 / S / M1 / M2 / M1, etc. are exemplified.
The S layer / total layer thickness ratio is 10 to 90%, preferably 20 to 80%, more preferably 30 to 70%.

The lower limit of the above ratio is the stretching force of the S layer when it is strongly stretched in the cold, and it is strong and uniform in the functional layer composed of a composition that cannot be cold-stretched by itself and cannot achieve opening. Is a ratio necessary for imparting stretching force (low temperature, high magnification region) to achieve stretch opening of the layer stably (without film tearing and surging).
The ratio may be determined so as to be optimal depending on the configuration of the M layer. For example, when the M layer includes a composition layer that is difficult to open by cold drawing, the lower limit of the S layer ratio is relatively high in the entire layer, and conversely, the M layer has a composition that is easy to open the target hole structure. Needless to say, a low S layer ratio is acceptable.
In the present invention, a composition mainly comprising a thermoplastic resin constituting at least one M layer, and preferably a composition mainly comprising a thermoplastic resin constituting at least one S layer, Each of them is thermoplasticized and melted in separate extruders, coextruded from a multilayer die, and then rapidly cooled and solidified to form a sufficiently uniform tube or sheet raw material, which are then stretch-molded.
Examples of the coextrusion method include a multilayer T-die method and a multilayer annular die method, and the latter method is preferable from the standpoints of good raw fabric efficiency and uniformity of flow orientation.

Next, as the stretch molding method, there are various methods such as a roll stretching method, a tenter frame method, and a tubular method (including a multi-bubble process such as double bubble and triple bubble). Generally, for the following reasons, It is preferable to use a tubular method, and it is more preferable to dispose at least one S layer thereon.
A sheet having a relatively thick thickness is extruded with a T die, quenched with a cast roll, heated between rolls, and uniaxially stretched, or preferably biaxially stretched. In this case, specifically, vertical uniaxial stretching between roll groups, horizontal uniaxial stretching with a tenter, simultaneous biaxial stretching with a tenter frame, and sequential biaxial stretching in combination of a roll and a tenter are employed.
A filamentous product is obtained by extruding the composition from the spinning hole, quenching with a cooling medium, and uniaxially stretching while heating.
In the hollow fiber form, the composition is extruded from a single layer or, if necessary, a multilayer hollow fiber die, quenched with a cooling medium, heated and stretched uniaxially or differentially in an appropriate temperature control medium while being extruded. It is obtained by stretching uniaxially between rolls.

Furthermore, before stretching or after stretching, 2 layers are added to the M layer and S layer for the purpose of enhancing the stretchability and stretchability of the original fabric and improving the strength, heat resistance and dimensional stability of the porous body of the present invention. The crosslinking treatment may be performed with a high energy beam of ˜20 Mrad, preferably 2.5 to 15 Mrad.
As a method at this time, ionizing radiation, for example, a method of irradiating an electron beam, a β ray or a γ ray emitted from a radioisotope, or a sensitizer such as benzophenone or peroxide is mixed in the M layer in advance. Examples of the method include ultraviolet irradiation and thermal crosslinking.
Among these, it is preferable to use a high energy electron beam industrially.
In the case of a multilayer M layer, the degree of cross-linking of a predetermined M layer can be determined by controlling the type of resin, molecular weight, additives (accelerating or suppressing cross-linking), etc. depending on the purpose, or transmission of energy rays. It may be controlled by controlling the depth (for example, increasing the cross-linking density of the surface layer, decreasing the cross-linking density of the intermediate layer, or performing weak cross-linking to such an extent that the gel fraction cannot be measured substantially).
Further, these crosslinking treatments may be applied to the S layer.

The characteristic value measurement method used in the present invention will be described below.
(1) The air permeability is a Gurley value (second / 100 cc) measured based on the ASTM D-726 (B) method, and represents a predetermined area as a time required for 100 cc of air to pass. It is a value converted to 25 μm. However, if the air permeability is low, that is, it is easy to pass through (for example, 5 sec or less), measure the number of films by overlapping (for example, 5 to 10) or by reducing the measurement area with a cover film or the like. Later, the value will be converted to match the original predetermined method.
(2) Crystal melting point (mp) and glass transition point (Tg) are based on JIS-K-7121, using a differential scanning calorimeter (DSC, DSC-7 manufactured by PerkinElmer Co., Ltd.) After being melted and rapidly cooled, the temperature was measured at a rate of temperature increase of 10 ° C./min from a predetermined temperature.

(3) The porosity (Po) is obtained by determining the volume (V) of the porous body by determining the volume (V) of the porous body and then subtracting the volume (J) of the resin composition forming the porous body. The value obtained by multiplying the divided ratio by 100 by volume (V) is represented by Po = (V−J) X100 / V.
(4) The average opening (opening) diameter of the opening (P) (opening (I)) is obtained by observing the surface of the porous body with a scanning electron microscope (SEM), and the diameter of 10 opening (opening) portions. It was obtained by averaging (minor axis in the case of an ellipse).
(5) Vicat softening point (VSP) is a value measured according to ASTM D1525 (load measured at 1 kg).

(6) Ring ball method softening point (BVSP) is a value measured according to JIS-K-2207.
(7) The tensile elastic modulus is a value measured according to ASTM-D882.

(8) The electrical resistance is a resistance value measured by an alternating current method (1 kHz) by replacing the space portion of the porous body with the electrolytic solution in an electrolytic solution for a lithium ion battery (film thickness is 25 μm in units of Ω · cm ² ). Conversion value).
(9) Battery safety performance (closure / short circuit) The temperature is about 150 kg of nickel as two electrodes in a container under a nitrogen pressurized atmosphere of about 1 kg / cm ² so that the electrolyte does not evaporate even when heated. An electrolytic solution for a lithium ion battery is injected into an electrolytic cell with a separator sandwiched between screen meshes made of nickel (or other metal screens plated with nickel), and a glass plate as an insulating plate on the outer sides of both electrodes. Set the surface pressure uniformly to 100 g / cm ² , flow alternating current, heat at a heating rate of 2 ° C / min, close the separator opening, and increase the electrical resistance suddenly. It represents the temperature at which the separator is melted and flown and the electrode is short-circuited (short-circuit temperature).

Next, an Example and a comparative example are given and this invention is demonstrated.
Examples of thermoplastic resin compositions used in the examples are shown below.
(1) As a thermoplastic resin (A) used as a base material, the following are used.
A-1: High density polyethylene resin, density 0.962 g / m ³ , MFR (210 ° C./2.16 kg) 0.8, VSP 120 ° C., mp 133 ° C.
A-2: Polypropylene, density 0.910 g / cm ³ , MFR (230 ° C./2.16 kg) 3.3, VSP 143 ° C., mp 160 ° C.
A-3: Poly-L-lactic acid of aliphatic polyester resin (copolymerized with 3 mol% of D-lactic acid), density 1.26 g / cm ³ , MFR (200 ° C./2.16 kg) 1.5, mp 174 ° C, VSP 58 ° C.
A-4: Polyglycolic acid of aliphatic polyester resin (5 mol% copolymerized L-lactic acid), density 1.57 g / cm ³ , mp 215 ° C., VSP 36 ° C.

A-5: 4-methylpentene-1 resin (density 0.834 g / cm ³ , mp 240 ° C., MFR (260 ° C./5 kg) 26, VSP 160 ° C.
A-6: α-olefin / carbon monoxide copolymer (copolymer of 6 mol% of propylene with 44 mol% of ethylene among α-olefin components) resin, density 1.235 g / cm ³ , MFR ( 240 ° C./2.16 kg), VSP (load 5 kg) 205 ° C.
A-7: Polysulfone resin, density 1.24 g / cm ³ , VSP 188 ° C., MFR (240 ° C./2.16 kg) 3.
A-8: Vinylidene fluoride resin (copolymerized with 10% by weight of hexafluoropropylene), density 1.79 g / cm ³ , VSP 140 ° C., MFR (230 ° C./2.16 kg) 1, mp 145 ° C.
A-9: Linear low density polyethylene, density 0.921 g / cm ³ , MFR (= MI) 1.0, mp 121 ° C.

(2) As the pore opening material (B), the following are used.
B-1: Polyphenylene ether: VSP 214 ° C., MFR (280 ° C./10 kg) 4 is 53% by weight, GPPS: VSP 105 ° C., MFR (200 ° C./5 kg) 7 is a compound resin of VSP 157 ° C. .
B-2: SMAA resin obtained by copolymerization of 86% by weight of styrene and 14% by weight of methacrylic acid and having characteristics of VSP 135 ° C. and MFR (230 ° C./3.8 kg) 1.6.
B-3: A resin obtained by hydrogenating a petroleum resin polymerized using cyclopentadiene as a main raw material and having a BVSP of 170 ° C. and a GPC number average molecular weight (Mn) of 1250.
B-4: An ethylene / carbon monoxide copolymer resin having VSP of 225 ° C., mp of 250 ° C., and Tg of 15 ° C.

B-5: Copolymerized polyamide resin (nylon 6-66) with mp 195 ° C. and MFR (230 ° C./2.16 kg) 3.5.
B-6: Cross-linked silicone resin powder having an average particle size of 0.5 μm and a particle size distribution of 0.2 to 1.3 μm (93% of the total).
B-7: Cross-linked silicone resin powder having an average particle size of 5.0 μm and a particle size distribution of 2.0 to 8.0 μm (95% of the total).
B-8: Cross-linked acrylic resin powder having an average particle size of 1.5 μm (95% in a distribution of 1.35 to 1.65 μm).
B-9: Spherical silica powder with an average particle size of 0.3 μm (98% distribution 0.20 to 0.50 μm).
Or what was described in the above-mentioned (B), and is a kind which is useful for opening of the pore wall described in the specification when used in combination with another pore-opening material which contributes to the primary hole.

(3) The following are used as the opening agent (C).
C-1: erucic acid amide C-2: sodium stearate C-3: higher fatty acid modified silicone oil (mp 64 ° C.)
C-4: Glycerin 12-hydroxystearate (mp 71-77 ° C.)
C-5: Paraffin wax (mp 58 ° C.)

(4) Next, the composition used as the auxiliary layer (S) is exemplified below.
S-1: Low-density polyethylene polymerized with a metallocene catalyst (4 mol% octene-1 copolymerized, density: 0.926 g / cm ³ , MI: 1.2) (E-1): 60 wt. Thermoplastic elastomer (density: 0.887 g / cm ³ , MI: 0.44) (E-2): 10% by weight, polypropylene (single site) Density polymerized with a system catalyst: 0.905 g / cm ³ , MFR: 1.4, mp; 153 ° C.) (E-3): 10% by weight, crystalline polybutene-1 (3.5 mol of propylene) % Copolymerized density: 0.907 g / cm ³ , MI: 1.6): 10% by weight, petroleum resin (hydrogenated saturated hydrocarbon, ring and ball softening point 125 ° C.): 10% by weight is sufficient To 100 parts by weight of the kneaded product, Nonylphenyl ether polyethylene oxide adduct 2.2 parts by weight of mixed composition as an additive.

S-2: Polypropylene (density: 0.905 g / cm ³ , MFR: 2.5, mp; 162 ° C.): 70% by weight (E-3), 85% by mole of ethylene and 15% by mole of butene-1 Polymerized thermoplastic elastomer (density: 0.890 g / cm ³ , MI: 0.90) (E-2) 15% by weight and petroleum resin (same as above) 15% by weight were mixed with 100 parts by weight of diglycerin mono A composition in which 2 parts by weight of laurate and 3 parts by weight of erucamide are mixed.
S-3: Copolyester resin (VSP copolymerized with terephthalic acid as an alcohol component, 30 mol% of cyclohexadimethanol and 70 mol% of ethylene glycol at 82 ° C).
S-4: crystalline polybutene-1 resin (copolymerized with 2 mol% of ethylene, density 0.905 g / cm ³ , MI: 1.1), 100 parts by weight, oleic acid amide 1.5 parts by weight, alkyl A composition in which 1.0 part by weight of silicone oil is mixed.

(Example 1)
For the base resin (functional layer: M1: porous body) layer constituting the inner layer, the base resin (A) has the above-mentioned A-1: 80% by weight, and then the pore-opening material (B) is B-1. : 10% by weight, as a modifier (stretchability modifier / compatibility dispersion regulator), hydrogenated styrene-butadiene block copolymer resin (derived from SBS type, bound styrene is 32% by weight, MFR: A composition obtained by adding 3 parts by weight of C-1 as an opening agent (C) to 100 parts by weight of a mixture of 10% by weight measured at 230 ° C / 2160g: 5) In a circular die having a layer structure of two types and three layers, using S-2 as an auxiliary layer for the surface layer (S) and then kneading and melting with separate extruders. Co-extrusion, quench molding with a cooling medium, and three layers of thickness ratio (S / M1 / S: 1/3/1) This tube is passed through between two pairs of feed nip rolls and take-up nip rolls, heated in a heating furnace to 82 ° C. with hot air, and then directly filled with air at the end of the process. While taking in with the nip roll, the inside is filled with air, is continuously expanded in the temperature control ring chamber, is finally quenched with the cooling ring, and the drawing is finished, and the draw ratio in the machine direction (flow direction: vertical) Is stretched so that the stretching ratio in the transverse direction (bubble diameter direction) is 5.0 times, and then air passes between another pair of feed nip rolls and take-up nip rolls, and air is introduced into the interior. Was heated to 115 ° C. with hot air from the circumferential direction and heat set for 30 seconds while shrinking 5% in the vertical direction and 5% in the horizontal direction. Finally, the stretched three-layer film was wound with a winder while slitting the ears at both ends. Next, the auxiliary layer (S layer) was peeled off with a winder for peeling. The M layer could be easily peeled off, no static electricity was generated at the time of peeling, and high-speed peelability (70 m / min) was also good.

Further, even during each process, there was appropriate adhesion between the respective layers, good stretching stability, no puncture phenomenon during drawing, no air bleeding phenomenon, and no peeling and separation. Moreover, the opening of the surface of the functional layer (M1) was not uniform as compared with the inner layer portion, and a defective phenomenon such as a skin structure was not observed, and the thickness was uniform in the thickness direction. The obtained uniform microfluidic porous film (M1) has a thickness of 23 μm, an air permeability of 5 sec / 100 cc · 25 μm (hereinafter, “/ 100 cc · 25 μm thickness” is omitted), and a porosity of 70. %, Electrical resistance 0.82 Ω · cm ² , maximum shrinkage 65%, and maximum shrinkage stress 220 g / mm ² .
The average pore diameter of the large pore group (P) is about 7 μm, the number of small aperture groups (I) in the bubble wall portion is 10 or more per bubble wall, the average diameter is about 0.13 μm, and the volume thereof. The ratio of the former (P) was 75% of the total.
As a result of assembling this film in a lithium ion battery of a single cell (with a separator and electrolyte inserted between the cathode and anode) and conducting a charge / discharge test (Rate 1C), “Comparative Sample-1” (from HDPE only) From “Phase Separation—After Biaxial Stretching—Same Plasticizer Extraction Method”, an electric resistance of 1.10 Ω · cm ² , an air permeability of 620 sec, and an aperture only in a group having a small aperture (average aperture of 0.04 μm) The charge / discharge curve was excellent.
Moreover, the “closure / short circuit” temperatures were “136 ° C./156° C.”, respectively, although they were single layer films, and the short circuit temperature was high. For comparison, “Comparative Sample-1” was in a narrow range of “138 ° C./146° C.”, respectively.

(Example 2)
For the base resin (functional layer: M2: porous body) layer constituting the inner layer, the base resin (A) has the aforementioned A-2: 65% by weight, and then the pore-opening material (B) is B-1. : 23 wt%, and as a modifier (stretchability modifier / compatibility dispersion modifier), hydrogenated styrene-butadiene block copolymer resin (same as in Example 1): 7 wt%, Furthermore, 100 parts by weight of a mixed resin comprising 5% by weight of polybutene 1 resin (specific gravity: 0.915, mp: 125 ° C., VSP: 111 ° C., MFR: 1.8) as a stretchability modifier for the substrate In addition, a composition obtained by adding 3 parts by weight of C-4 as an opening agent (C) is sufficiently kneaded with a twin-screw extruder, and then S-- as an auxiliary layer for the surface layer (S). 1 and kneaded and melted in separate extruders, and co-pressed with a circular die having a layer structure of 2 types and 3 layers Then, it is rapidly cooled with a cooling medium to form a three-layer uniform tube-shaped raw material having a thickness ratio (S / M2 / S: 1/1/1), and this raw material is taken up with two pairs of feed nip rolls. Pass between the nip rolls and heat in a heating furnace to 75 ° C with hot air, and then take in the air-filled nip roll at the end of the process as it is. Finally, it is rapidly cooled with a cooling ring to finish stretching, and the stretching ratio in the machine direction (flow direction; vertical) is 4.5 times, and the stretching ratio in the transverse direction (bubble diameter direction) is 4 times. Then, between two pairs of feed nip rolls and take-up nip rolls, the inside is filled with air, made into a tube, heated to 120 ° C. with hot air from the circumferential direction, and 5 in the vertical direction. %, 20 seconds while shrinking 6% in the horizontal direction Heat set for a while. Finally, two stretched three-layer films were each wound up by a winder while slitting the ears at both ends. Next, the auxiliary layer (S layer) was peeled off with a winder for peeling. The M layer could be easily peeled off, no static electricity was generated at the time of peeling, and there was no problem with high-speed peelability (100 m / min).

Further, even during each process, there was appropriate adhesion between the respective layers, good stretching stability, no puncture phenomenon during drawing, no air bleeding phenomenon, and no peeling and separation. There are no non-uniform openings in the surface layer and it is uniform in the thickness direction. The resulting uniform microfluidic porous film has a thickness of 25 μm, an air permeability of 15 sec, a porosity of 73%, an electrical resistance of 1.12 Ω · cm ² , the maximum shrinkage was 50%, and the maximum shrinkage stress was 340 g / mm ² . The average pore size of the large pore group (P) is about 10 μm, the number of small aperture groups (I) in the bubble wall portion is 10 or more per bubble wall, the average aperture is about 0.09 μm, and the volume The ratio of the former (P) was 80% overall.
As a result of assembling this film into a lithium ion battery of a single cell (with a separator and an electrolyte inserted between the cathode and anode) and conducting a charge / discharge test (Rate 1C) The discharge curve was excellent.
Further, the “closure / short circuit” temperatures were “165 ° C./200° C.”, respectively, although the film was a single layer film, and the short circuit temperature was high.

(Example 3)
In the same manner as in Example 2, the functional layer (M1) of Example 1 is arranged in the middle of the functional layer (M2) part of Example 2 to make “M2 / M1 / M2”, and similarly, the three types, five layers The layer structure is “S1 / M2 / M1 / M2 / S1” for each of the curled dies. Similarly, the thickness ratio (1/1/1/1/1) is set to obtain a uniform tube-shaped original fabric. In the same manner as in Example 2, it is heated to 70 ° C. with hot air, and then taken in with the air-filling nip roll at the end of the process, air is introduced inside, and it continuously expands in the temperature control ring chamber. Finally, it is rapidly cooled with a cooling ring to finish stretching, and the stretching ratio in the machine direction (flow direction; vertical) is 4.0 times, and the stretching ratio in the transverse direction (bubble diameter direction) is 3.5 times. And then another set of two pairs of feed nip roll and take-up nip 4% in the longitudinal direction and heated to 120 ° C. with hot air from the circumferential direction in the form sealed air tube therein through during and 15 seconds heat set while 6% shrinkage in the transverse direction.
Finally, the two stretched five-layer films were each wound up by a winder while slitting the ears at both ends.
Next, the auxiliary layer (S layer) was peeled off with a winder for peeling. The S layer could be easily peeled off, no static electricity was generated at the time of peeling, and there was no problem because the functional layers were not peeled even at high speed peelability (100 m / min).

Further, even during each step, each layer had appropriate adhesion, good stretching stability, no puncture phenomenon during drawing, no air bleeding phenomenon, and no peeling and separation. Further, the surface layer on the S layer side of the functional layer and the interface between the functional layers were uniform and had substantially no influence on the fluid flow performance.
The obtained three-layer uniform microfluidic porous film has a thickness of 27 μm, an air permeability of 10 sec, an average (in three layers) porosity of 63%, an electric resistance of 0.96 Ω · cm ² , and a maximum shrinkage of 53 %, The maximum shrinkage stress was 240 g / mm ² . The average pore diameter of the large pore group (P) was about (9/5) μm in each layer (M2 / M1), and the number of small aperture groups (I) in the bubble wall portion was one bubble wall. On the other hand, the number was 10 or more, and the average diameter was about (0.09 / 0.08) μm, respectively. The volume ratio of (P) was about (70/63)% of the total.
As a result of conducting a charge / discharge test (Rate 1C) on this film in the same manner as in Example 1, the charge / discharge curve was superior to the film of “Comparative Sample-1”. Moreover, the “closure / short circuit” temperatures were “134 ° C./200° C.”, respectively, and the temperature difference was 66 ° C., which had a wide temperature characteristic.

Example 4
In the same manner as in Example 3 (however, the composition constituting the intermediate layer of the functional layer is replaced with the following composition), the above-mentioned A as the base resin (functional layer: M-3) of the intermediate layer of the functional layer -9: 70% by weight, B-1: 25% by weight as the pore-opening material (B), and 5% by weight of the same hydrogenated styrene-butadiene block copolymer as in Example 1 A composition obtained by mixing 2 parts by weight of C-3 as an opening agent (C) is used in parts by weight, the functional layer is “M2 / M3 / M2,” and S-3 is used as an auxiliary layer for the surface layer (S). The heating temperature at the time of stretching was 64 ° C., and then the same treatment as in Example 3 was performed except that the heat treatment temperature after stretching was 105 ° C., and the surface layer (S) was peeled off from the obtained film to function three layers. A film having a thickness of 26 μm was obtained. This film had an air permeability of 15 sec, an average porosity of 65%, an electric resistance of 1.06 Ω · cm ² , a maximum shrinkage of 59%, and a maximum shrinkage stress of 270 g / mm ² .

The average pore diameter of the large pore group (P) was about (5/3) μm in each (M2 / M3) layer.
The number of small aperture groups (I) in the bubble wall portion was 10 or more per bubble wall, and the average diameter was about (0.08 / 0.05) μm, respectively. The volume ratio of (P) was about (63/68)% of the total.
The “clogging / short-circuiting” temperature of this film in the same method was “120 ° C./200° C.”, and the difference was 80 ° C. and had the same temperature characteristics in a wide range.

(Example 5)
For the base resin (functional layer: M4: porous body) layer constituting the inner layer, the base resin (A) has A-3; 83% by weight as described above, and then the pore opening material (B) has B-4. : 10% by weight, as a modifier (stretchability modifier / compatibility dispersion regulator), hydrogenated styrene-butadiene block copolymer resin (derived from SBS type, bound styrene is 32% by weight, MFR: A composition obtained by adding 3 parts by weight of B-9 as an opening agent (C) to 100 parts by weight of a mixture of 7% by weight measured at 230 ° C./2160 g: 5 twin screw extruder Then, for the surface layer (S), S-2 is used as an auxiliary layer, and the draw ratio is “vertical (machine direction) / horizontal (direction perpendicular to the machine direction)” (hereinafter the same). In each case, the heating temperature during stretching was set to 75 ° C., and the heat treatment was performed using a tenter. A treatment was carried out in the same manner as in Example 1 except that the frame was used, and the surface layer (S) was easily peeled off to obtain a uniform porous film.
This film had a thickness of 28 μm, an air permeability of 15 sec, a porosity of 74%, an electric resistance of 1.12 Ω · cm ² , a maximum shrinkage of 69%, and a maximum shrinkage stress of 120 g / mm ² .
The average pore diameter of the large pore group (P) is about 32 μm, the number of small aperture groups (I) in the bubble wall portion is 10 or more per bubble wall, the average aperture is about 0.43 μm, and the above ( The volume ratio of P) was 78%.

(Example 6)
In the same manner as in Example 5, for the functional layer (M5) of the inner layer, A-4: 86% by weight as the base resin (A), and then B-7: 7% by weight as the aperture material (B) % And polybutene 1 resin (same as that used in Example 2): 7 parts by weight of 100 parts by weight of the mixture, and 3 parts by weight of B-6 as the opening agent (C) The composition formed by using S-2 as an auxiliary layer, the heating temperature at the time of stretching was set to 73 ° C., and others were obtained in the same manner as in Example 5 to obtain a uniform porous film. This film had a thickness of 25 μm, The air permeability was 20 sec, the porosity was 70%, the electric resistance was 1.40 Ω · cm ² , the maximum shrinkage was 72%, and the maximum shrinkage stress was 80 g / mm ² .
The average pore size of the large pore group (P) is about 22 μm, the number of small aperture groups (I) in the bubble wall portion is 10 or more per bubble wall, the average aperture is about 0.8 μm, and the above ( The volume ratio of P) was 75%.

(Example 7)
In the same manner as in Example 6, for the functional layer (M6) of the inner layer, A-5: 73% by weight as the base resin (A), and then B-3 and B- as the opening material (B) Mixing compound having a ratio of 1/1: 17% by weight and polybutene 1 resin (same as that used in Example 2): 10% by weight as a modifier: As (C), a composition obtained by adding 3 parts by weight of C-2, S-2 as an auxiliary layer, heating temperature at stretching at 70 ° C., and stretching ratio “vertical / horizontal” at “4” .5 / 4.2 ", and otherwise obtained a uniform porous film.
This film had a thickness of 20 μm, an air permeability of 14 sec, a porosity of 70%, an electric resistance of 1.0 Ω · cm ² , a maximum shrinkage of 72%, and a maximum shrinkage stress of 380 g / mm ² .
The average pore size of the large pore group (P) is about 35 μm, the number of small aperture groups (I) in the bubble wall portion is 10 or more per bubble wall, the average aperture is about 0.06 μm, and ( The volume ratio of P) was 75%.

(Example 8)
In the same manner as in Example 6, for the functional layer (M7) of the inner layer, A-3: 73% by weight as the base resin (A), and then B-1 and B- as the opening material (B) Mixing compound of ratio 1/1 of 2: 17% by weight and polybutene 1 resin (same as used in Example 2) as a modifier: 100% by weight of the mixture of 10% by weight of the opening agent (C) As a composition obtained by adding 3 parts by weight of C-2, and for the functional layer (M8) of the next inner layer, A-4: 75% by weight as the base resin (A), As a pore opening material (B), a mixed compound having a ratio of B-1 and B-2 of 1/1: 15% by weight, and as a modifying material, polybutene 1 resin (the same as that used in Example 2): 10 A composition obtained by adding 3 parts by weight of C-3 as an opening agent (C) to 100 parts by weight of a mixture of , M7 / M8 / M7 in order of the ratio 1/1/1, then using S-3 as an auxiliary layer, heating temperature during stretching at 70 ° C., stretching ratio “vertical / horizontal” Were each set to “4.5 / 4.2”, and the others were obtained in the same manner as in Example 6 to obtain a uniform porous film having a thickness of 50 μm, an air permeability of 10 sec, a porosity of 76%, and an electric resistance of 1 .3 Ω · cm ² , maximum shrinkage rate 72%, maximum shrinkage stress 38
The average pore diameter of the large pore group (P), which was 0 g / mm ² , was about 30 μm, the number of small aperture groups (I) in the bubble wall portion was 10 or more per bubble wall, and the average aperture was About 0.8 μm, and the volume ratio of the above (P) was 75%.

Example 9
In the same manner as in Example 6, for the functional layer (M9) of the inner layer, A-6: 73% by weight as the base resin (A), and then B-1 and B- as the opening material (B) 100% by weight of a mixture of 9: 4/1 mixed compound: 10% by weight and, as a modifier, hydrogenated styrene-butadiene block copolymer resin (same as used in Example 5): 4% by weight The composition obtained by adding 3 parts by weight of C-5 as an opening agent (C) to the part, and S-4 as an auxiliary layer was used. The heating temperature during stretching was 110 ° C., and the stretching ratio was “vertical”. “Horizontal” was changed to “3.7 / 3.2”, respectively, and a uniform porous film was obtained in the same manner as in Example 6. This film had a thickness of 29 μm, an air permeability of 24 sec, a porosity of 72%, an electrical resistance of 1.1 Ω · cm ² , a maximum shrinkage of 70%, and a maximum shrinkage stress of 180 g / mm ² .
The average pore diameter of the large pore group (P) is about 15 μm, the number of small aperture groups (I) in the bubble wall portion is 10 or more per bubble wall, and the average aperture is about 0.05 μm. The volume ratio of P) was 85%.

(Example 10)
In the same manner as in Example 6, for the functional layer (M10) of the inner layer, A-7: 86% by weight as the base resin (A), and then B-8 and B- as the opening material (B) 100% of a mixture of 10% by weight of a mixed compound with a ratio of 9 to 9 and 10% by weight and a hydrogenated styrene-butadiene block copolymer resin (same as that used in Example 5) as a modifier: 4% by weight. A composition obtained by adding 3 parts by weight of C-3 as an opening agent (C) to parts by weight, and S-2 as an auxiliary layer, heating temperature during stretching at 120 ° C., stretching ratio “vertical” “Horizontal” was changed to “3.5 / 3.2”, respectively, and a uniform porous film was obtained in the same manner as in Example 6. This film had a thickness of 23 μm, an air permeability of 14 sec, a porosity of 68%, an electrical resistance of 1.3 Ω · cm ² , a maximum shrinkage of 64%, and a maximum shrinkage stress of 150 g / mm ² .
The average pore size of the large pore group (P) is about 8 μm, the number of small aperture groups (I) in the bubble wall portion is 10 or more per bubble wall, the average aperture is about 0.08 μm, and the above ( The volume ratio of P) was 85%.

(Example 11)
In the same manner as in Example 6, for the functional layer (M11) of the inner layer, A-8: 86 wt% as the base resin (A), and then B-1: 10 wt as the aperture material (B) %, And as a modifier, hydrogenated styrene-butadiene block copolymer resin (same as that used in Example 5): 4% by weight of a mixture of 100% by weight as an opening agent (C), C − The composition formed by adding 3 parts by weight of 4 and S-3 as an auxiliary layer, the heating temperature during stretching is 90 ° C., and the stretching ratio “vertical / horizontal” is “4.5 / 4.2”, respectively. Otherwise, a uniform porous film was obtained in the same manner as in Example 6.
This film had a thickness of 25 μm, an air permeability of 12 sec, a porosity of 75%, an electric resistance of 0.85 Ω · cm ² , a maximum shrinkage of 74%, and a maximum shrinkage stress of 250 g / mm ² .
The average pore size of the large pore group (P) is about 35 μm, the number of small aperture groups (I) in the bubble wall portion is 10 or more per bubble wall, the average aperture is about 0.10 μm, and ( The volume ratio of P) was 75%.

(Example 12)
In the same manner as in Example 6, for the functional layer (M12) of the inner layer, A-9: 81 wt% as the base resin (A), and then B-1 and B- as the pore opening material (B) 5: Mixing ratio of 4/1: 15% by weight and, as a modifier, hydrogenated styrene-butadiene block copolymer resin (same as used in Example 5): 4% by weight A composition obtained by adding 3 parts by weight of C-4 as an opening agent (C) to 100 parts by weight of the mixture with S-3 as an auxiliary layer, and the heating temperature during stretching is 60 ° C. A uniform porous film was obtained in the same manner as in Example 6 except that the draw ratio “vertical / horizontal” was set to “4.8 / 4.5”, respectively.
This film had a thickness of 29 μm, an air permeability of 22 sec, a porosity of 65%, an electric resistance of 1.25 Ω · cm ² , a maximum shrinkage of 78%, and a maximum shrinkage stress of 320 g / mm ² .
The average pore size of the large pore group (P) is about 25 μm, the number of small aperture groups (I) in the bubble wall portion is 10 or more per bubble wall, and the average aperture is about 0.15 μm, The volume ratio of (P) was 85%.

(Example 13)
In the same manner as in Example 2, for the functional layer (M13), A-5: 72% by weight as the base resin (A), and then B-1: 20% by weight as the aperture material (B) A composition obtained by adding 4 parts by weight of C-4 as an opening agent (C) to 100 parts by weight of a composition obtained by kneading the above polybutene-1: 8% by weight as a texture agent, and then a functional layer ( For M14), A-9: 72% by weight as the base resin (A), then B-2: 20% by weight as the pore opening material (B), polybutene-1: 8% by weight as the modifier A composition obtained by adding 4 parts by weight of C-2 as an opening agent (C) to 100 parts by weight of a composition obtained by kneading the composition with a functional layer of “M13 / M14 / M13”, and an auxiliary layer As (S), S-2 is used, the stretching ratio is “5.0 / 4.5” for each stretching ratio “vertical / horizontal”, and the stretching temperature Stretched at 65 ° C., the other is heat-treated in the same manner as in Example 2, to obtain a film having a three-layer peeling off the S layer.

This film has a thickness of 25 μm, an air permeability of 19 sec, an average (in three layers) porosity of 63%, an electric resistance of 1.06 Ω · cm ² , a maximum shrinkage of 79%, and a maximum shrinkage stress of 340 g /
was mm ^2, the average pore size of the large pore group (P) is a (M2 / M1) layers were each about (15/7) [mu] m. The number of small aperture groups (I) in the bubble wall portion is 10 or more per bubble wall, and the average aperture is about (0.10 / 0.05) μ respectively.
The porosity of each of the M11 and M12 monolayers prepared separately under the same stretching and processing conditions was (66/58)%, respectively. The volume ratio of (P) was about (80/73)%, respectively.
The “occlusion / short circuit” temperatures of this film were “114 ° C./235° C.”, respectively, and the temperature difference was 121 ° C. and the temperature characteristics were wide.

(Example 14)
In Example 2, after the stretching heat treatment, the heating temperature was further set to 90 ° C., the stretching ratio was doubled and the width was 1.8 times, and the same heat treatment was performed. Finally, two stretched three-layer films were each wound up by a winder while slitting the ears at both ends. Next, the auxiliary layer (S layer) was peeled off with a winder for peeling, and the M layer could be easily peeled off. No static electricity was generated during peeling, and high-speed peelability (100 m / min) was problematic. Furthermore, each layer had appropriate adhesion in each step, good stretching stability, no puncture phenomenon during drawing, no air bleeding phenomenon, and it did not peel off during the process. Also, the surface layer has no non-uniform openings and is uniform in the thickness direction. The obtained uniform fine fluid-permeable porous film has a thickness of 30 μm, an air permeability of 0.8 sec, a porosity of 79%, and an electric resistance. The maximum shrinkage was 0.65 Ω · cm ² , the maximum shrinkage was 70%, and the maximum shrinkage stress was 440 g / mm ² . Further, the large pore group (P) and the small opening group (I) in the bubble wall portion were destroyed and fibrillated, and could not be clearly identified. This film was wetted, sulfonated with fuming sulfuric acid, as a nickel-hydrogen battery separator, assembled into a battery with a separator and electrolyte inserted between the cathode and anode, and subjected to charge / discharge test results in life characteristics, The electric capacity characteristics and charging / discharging characteristics at a high rate were good, the internal pressure was not increased due to insufficient mobility of the generated gas, and the self-discharge was small even in the long-term storage test at 40 ° C. after the charging.

(Example 15)
In Example 1, it carried out similarly to Example 1 except changing only the thickness at the time of extrusion, and the thinner porous film was obtained. The obtained film had a thickness of 8 μm, an air permeability of 2 sec, and a porosity of 70%.
This porous film M1 and a polypropylene porous film M2 (thickness 8 μm, air permeability 200 sec, porosity 40%) obtained by the stretch opening method are laminated and laminated so that M2 / M1 / M2 is obtained. A fluid porous film was obtained.
As a result of conducting a charge / discharge test (Rate 1C) on this film in the same manner as in Example 1, the charge / discharge curve was superior to the film of “Comparative Sample-1”.
The “closure / short circuit” temperatures were “134 ° C./190° C.”, respectively, and the temperature difference was 56 ° C., which was a wide temperature characteristic.

It is the schematic of an opening (P) and opening (I) when the surface of a porous body is observed with a scanning electron microscope (SEM).

Claims (14)

  From 50 to 99% by weight of the base material thermoplastic resin (A) to be a continuous phase, and 1 to 50% by weight of the total amount of the pore-opening material (B) and the opening agent (C) mixed and dispersed therein. By stretching the molded body of the microporous body forming precursor composition, at least a part of the interface between the thermoplastic resin (A) of the base material and the pore opening material (B) and the opening agent (C) is peeled off. A fine fluid-permeable porous body of thermoplastic resin formed by the formation of the opening (P) and the opening (I), the porous body having a large opening having an average pore diameter of 0.5 to 100 μm. A hole (P) group and a smaller opening (I) group having an average opening diameter of 0.01 to 30 μm in at least a part of the opening wall portion of the opening (P), and air permeability Is 1000 (sec / 100 cc · 25 μm thickness) or less, and the porosity is 30 to 90%. Porous material.   The microfluidic porous body according to claim 1 is further stretched to form at least a part of at least one part of the aperture (P) group and the aperture (I) group. 1 part has a non-woven fibrillated structure, air permeability is 0.05 to 500 (sec / 100 cc · 25 μm thickness), and porosity is 30 to 90%. Fluid-permeable porous body.   The thermoplastic resin (A) is 55 to 98% by weight, the pore-opening material (B) is 2 to 45% by weight, and the opening agent (C) is 0 to 15% by weight. The fine fluid-permeable porous material according to 1 or 2.   The thermoplastic resin (A) is 60 to 94% by weight, the pore-opening material (B) is 5 to 40% by weight, and the opening agent (C) is 1 to 10% by weight. The fine fluid-permeable porous body according to any one of 1 to 3.   The thermoplastic resin (A) is a polyolefin resin, an aliphatic polyester resin, a polyester resin containing an aromatic component, an α-olefin and carbon monoxide copolymer, a polyamide resin, a fluorine resin, or a polysulfone resin. The fine fluid-permeable porous body according to any one of claims 1 to 4, comprising at least one selected.   The pore-opening material (B) is made of at least one resin selected from polyphenylene ether resins, styrene resins, and saturated hydrocarbon resins having a ring and ball softening point of 150 ° C or higher. The microfluidic porous material according to item.   Opening material (B) is a composition of polyphenylene ether resin and styrene resin, composition of polyphenylene ether resin and saturated hydrocarbon resin, polyphenylene ether resin, styrene resin and saturated hydrocarbon resin The fine fluid-permeable porous body according to any one of claims 1 to 6, comprising one kind of composition selected from the composition.   The porous body has at least two 0.01-30 μm pores on a large aperture (P) group having an average pore diameter of 0.5-100 μm and at least one aperture wall portion of the aperture (P). A smaller aperture (I) group having an average aperture diameter, an average diameter ratio (P / I) of at least 2, and an air permeability of 0.5 to 500 (sec / 100 cc · 25 μm thickness) The microfluidic porous body according to any one of claims 1 to 7, wherein the porous body has a hybrid structure.   The porous body is one type selected from a film shape having a thickness of 2 to 200 μm, a sheet shape having a thickness of 200 to 5000 μm, a thread shape having a diameter of 2 to 5000 μm, and a hollow fiber shape having a diameter of 2 to 5000 μm. The fine fluid-permeable porous body according to any one of 1 to 8.   2. The porous body is a multilayer composed of a combination of one or more layers selected from layers having different compositions or layers having different structures and layers having different properties. The fine fluid-permeable porous material according to any one of? 9.   The microfluidic fluid according to any one of claims 1 to 10, wherein the porous body has a porosity of 30 to 80% and an air permeability of 0.5 to 500 (sec / 100 cc · 25 µm thickness). Porous material.   11. The microfluidic fluid according to claim 1, wherein the porous body has a porosity of 40 to 85% and an air permeability of 0.1 to 80 (sec / 100 cc · 25 μm thickness). Porous material.   The method for producing a microfluidic porous body according to any one of claims 1 to 12, wherein the microporous body-forming precursor layer based on at least one thermoplastic resin (A), And co-stretching a stretching auxiliary layer (S) of a composition comprising a thermoplastic resin different from the resin constituting the at least one precursor layer as a main component and which does not become a fluid-permeable structure by stretching, A method for producing a microfluidic porous material, wherein the auxiliary layer is peeled and removed.   It is a multilayer microfluidic porous body consisting of two or more layers, and at least one layer is the microfluidic porous body according to any one of claims 1 to 12, wherein the other layers are A microfluidic porous body characterized by a porous structure having a different characteristic.

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