JP2000198866A - Fluid-penetrable finely porous film and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fluid-penetrable finely porous film whose performance can be controlled for each target and which has a high performance, a reduced thickness and excellent productivity, by stretching a specific composition containing an α-olefin-carbon monoxide copolymer. SOLUTION: This fluid-penetrable fine porous film comprises at least one thermoplastic resin layer consisting mainly of (A) an α-olefin-carbon monoxide copolymer resin and having a crystal melting point of 140-250 deg.C, and has a porosity of 30-80%, an air permeability of 5-2,000 sec/100 cc and a 10% contraction temperature of >=100 deg.C. The film is obtained by extruding a composition consisting mainly of the component A and/or (B) a polyolefin resin having a crystal melting point of 80-240 deg.C and 85-10 pts.vol. of (C) an inactive extractable organic liquid having a viscosity of <=1,000 cPs at 200 deg.C through a die, quenching and solidifying the extruded film with a heat-conductive medium, stretching the film at least in one direction in a surface-stretching ratio of 2-50 times under a specific temperature condition, and then extracting the component C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heat-resistant, fluid-permeable, microporous film and a method for producing the same. The microporous film of the present invention can be used for battery materials such as various cylindrical batteries, prismatic batteries, thin batteries, button batteries, thin polymer batteries or separators used for capacitors, electrolytic capacitors, etc. Separation membranes), breathable film materials for building dew condensation prevention, materials for moisture-permeable wallpapers,
Non-permeable and moisture-permeable clothing, non-permeable and moisture-permeable film for sanitary products such as diapers and sanitary goods, packaging film that is permeable and prevents the passage of bacteria and dust, highly whitened light Used for reflective film, heat insulating / buffering material, printing paper material, etc.

[0002]

2. Description of the Related Art A microporous body of crystalline high-density polyethylene (HDPE) or crystalline polypropylene (PP), which is a polyolefin (PO) resin, having a thickness of 25 to 10
About 0μ, 0.01μ to 5μ penetrating in the thickness direction
Microporous films having a degree of communication holes are known.

[0003] These films are generally air permeable (sec / 1).
00 cc) has gas permeability and water resistance of about 10 to 1000, and has been used in many applications requiring such performance. For example, since it is ion-permeable in an electrolytic solution, it is also used as an insulating membrane between electrodes for batteries and the like.

Conventionally, such a porous film is produced by, for example, (1) heating and dissolving a highly crystalline HDPE in a large amount of a plasticizer (45 to 80 vol% by volume) to form a gel; Next, the film is extruded into a film or sheet, cooled, and the resin is solidified and crystallized.After phase separation with the plasticizer, the plasticizer is extracted with a solvent to form microporous nuclei, and then the film is stretched. A method of manufacturing by growing and expanding micropores,

(2) When the crystalline resin is melted and extruded into a sheet, the crystal is grown by flowing (orienting the molecules in the flow direction to some extent) in the longitudinal (flow) direction and annealing in the next step. And clarify the interface, and further perform cold stretching in the uniaxial (longitudinal) direction to form micropores at the crystal interface.
Then, a method of hot stretching to grow large (for example,
Japanese Patent Publication No. 55-32531),

(3) A method in which a soluble filler is added to form a film, and then the filler is eluted to make the film microporous (see, for example, JP-A-58-29839).
A method in which a composition to which a filler is added is blown directly from a die to make the composition porous (for example, Japanese Patent Application Laid-Open No. 2-27
No. 6834) is known.

[0007] As described above, these microporous films are used in many fields. For example, in the field of separation membranes and battery separators, property deterioration such as sterilization before use or aging during use is observed. For the prevention, those having excellent heat resistance, solvent resistance, dimensional stability, etc. are required, and in addition, high performance, high strength, thin film, cost reduction, etc. are also required.

[0008] In the case of a new type of secondary battery which has recently attracted attention, particularly in the case of a diaphragm of a lithium secondary battery, a so-called low-temperature fuse (current interruption due to an increase in resistance) in which a heat-resistant layer and a layer melting at a relatively low temperature are combined. High safety, high strength, and thin multi-layers that have the property of preventing the battery from melting down and preventing both electrodes from shorting and causing the battery to burst or ignite up to the high temperature range. A systemic diaphragm is desired. Then, as the use for electric vehicles and the like expands, the above-mentioned safety will be required more and more.

[0009]

In order to provide a microporous film having the required characteristics, conventionally, heat-resistant PP and HDPE having relatively low heat resistance are separately separated under optimum conditions. After heat treatment and uniaxial (longitudinal) stretching to make it porous, a heat-resistant PP layer is combined,
A method of laminating by hot pressing to form a multilayer has been used. However, these methods involve many steps, are difficult to control, have poor quality and productivity, and are insufficient in performance (for example, many have extremely poor tear strength balance).

Further, in the conventional method of including a large amount of filler, communication opening characteristics are imparted at the expense of strength, pore characteristics and the like, but it has been difficult to satisfy the above required characteristics.

Further, a density of 0.960 g / d, which is a method of the above-mentioned (2) which is a typical method of a dry method (no extraction).
cm ³ or more high-density polyethylene (HDPE) with a high magnification ratio drawdown ratio (hereinafter referred to as DDR) 20 to 200, after the extrusion, followed by cooling to prepare a raw sheet in an unstable state, which the HDPE 10 to 25 ° C from the crystal melting point of
Annealing at a low temperature range for a long time (having a large effect on a continuous process for 30 seconds to 1 hour) to grow a crystal to a large size, and then at a low temperature of -20 to 50 ° C. and a relatively low speed. One axis between differential rolls (longitudinal)
A method of obtaining a microporous film composed of HDPE by stretching the film in a cold direction, followed by uniaxial heat stretching at a temperature lower than the crystal melting point of the HDPE by 10 ° C. to 25 ° C. and at a slower speed. (Japanese Patent Application Laid-Open No. 62-121737)
issue).

A similar method has been known for PP resin (JP-B-46-40119). However, in these methods, the stretching speed is low, the efficiency is not good, and if the stretching ratio is increased beyond the range disclosed in the longitudinal (flow) direction in order to increase the porosity, a yarn-like yarn like a split yarn is formed. In addition, when the film is stretched in the horizontal direction to improve the strength, there is a problem that the precursor is torn during the stretching or a necking phenomenon occurs, so that a uniform microporous film cannot be obtained.

On the other hand, in the above method (4) in which the thermoplastic resin contains a filler, 90 to 35% by volume of the thermoplastic resin and 10 to 65% by volume of the filler are mixed and extruded to obtain a DDR of 10%.
Inflation directly from a die or a sheet shape within a range not exceeding 1.5 to 6 in at least one direction
A method of stretching the film twice to obtain a microporous film is generally used, but this method also has a problem that the filler is contained in a large amount, so that the film is brittle or the particles are shed.

[0014]

In order to solve the above-mentioned problems of the prior art, the present inventors can select a wider variety of resins as raw materials, can control the performance for each purpose, and can improve the performance. Research was conducted on a method of efficiently producing a thinner fluid-permeable microporous film with higher performance.

As a result, a special auxiliary layer is used for the production, preferably by a circular method, and in a region where stretching conditions of low temperature and high magnification (especially simultaneous biaxial stretching) are impossible with a single layer,
Moreover, it is possible to stretch even a resin that is difficult to stretch uniformly with a single layer, and it satisfies all of the objectives of high strength, thinning, and uniformity, and a multi-layer function with two or more functional layers. Has reached a revolutionary method of the present invention in which a conductive film can be efficiently obtained.

That is, the present invention provides: (1) at least one layer of a thermoplastic resin (A) containing, as a main component, a copolymer resin of an α-olefin and carbon monoxide having a crystal melting point of 140 to 250 ° C. Porosity 30-8
0% and air permeability of 5 to 2000 sec / 100 cc
And a heat-permeable microporous film having a 10% shrinkage temperature of 100 ° C. or higher,

(2) α- having a crystalline melting point of 140 to 250 ° C.
At least one thermoplastic resin (A) layer mainly composed of a copolymer resin of olefin and carbon monoxide, and at least one layer mainly composed of a polyolefin resin having a crystal melting point of 80 to 240 ° C. A resin having heat resistance of at least two layers of a plastic resin (B) layer having a porosity of 30 to 80%, an air permeability of 5 to 2000 sec / 100 cc, and a 10% shrinkage temperature of 100 ° C. or more. A fluid microporous film, and

(3) At least two layers including a surface layer, a thermoplastic resin (A) layer mainly composed of a copolymer resin of α-olefin and carbon monoxide having a crystal melting point of 140 to 250 ° C. It is composed of at least a three-layer microporous film composed of at least one layer including an inner layer of a thermoplastic resin (B) having a melting point of 80 to 240 ° C. and containing a polyolefin resin as a main component, and has a porosity of 30 to 80%. , Air permeability is 5
It is intended to provide a fluid-permeable microporous film having heat resistance of 2000 sec / 100 cc and a 10% shrinkage temperature of 100 ° C. or more, and a method for obtaining the film.

(4) α- having a crystal melting point of 140 to 250 ° C.
15 to 90 parts by volume of a thermoplastic resin (A) containing a copolymer resin of olefin and carbon monoxide as a main component, is extractable, and has a viscosity at 200 ° C. of 1000 CPS or less,
In addition, a microporous forming precursor layer composed of a composition containing 85 to 10 parts by volume of an inert organic liquid substance (C) as a main component is extruded by a die, quenched and solidified directly or indirectly by a heat transfer medium, and then cooled by a heat transfer medium. Area stretching in at least one direction at a temperature not lower than 50 ° C. and not higher than the temperature obtained by adding 50 ° C. to the Vicat softening point of the thermoplastic resin (A) constituting the precursor layer, and not higher than the crystal melting point of the resin. 2 times or more at 50 times
A method for producing a heat-resistant, fluid-permeable, microporous film, characterized in that the microporous film is obtained by stretching the material (C) before and after the stretching, and

(5) α- having a crystal melting point of 140 to 250 ° C.
A thermoplastic resin (A) containing a copolymer resin of olefin and carbon monoxide as a main component, and a crystal melting point of 80 to 240 ° C.
15 to 90 parts by volume of a thermoplastic resin (B) containing a polyolefin resin as a main component,
At least one microporous forming precursor layer comprising a composition having a viscosity at 100 ° C. of 1000 CPS or less and containing 85 to 10 parts by volume of an inert organic liquid substance (C) as a main component,
Extruded with a multilayer die, quenched and solidified directly or indirectly with a heat transfer medium, and then heated to 15 ° C. or higher and the Vicat softening point of the thermoplastic resin (A) constituting the precursor layer is increased by 5%.
At a temperature not higher than 0 ° C. and at a temperature not higher than the crystal melting point of the resin, the film is stretched in at least one direction by an area stretching ratio of 2 to 50 times, and before and after the stretching, the material (C) A method for producing a heat-resistant, fluid-permeable microporous film having at least two layers obtained by extracting

(6) α- having a crystal melting point of 140 to 250 ° C.
99 to 50 parts by volume of a thermoplastic resin (A) mainly containing a copolymer resin of olefin and carbon monoxide, and D1 to
A composition containing 1 to 50 parts by volume of at least one kind of stretch-openable substance (D) selected from D4. D1: a difference in solubility parameter with the resin (A) as a base material is within 3 and an elastic modulus. Is 1 to 50 parts by volume of a thermoplastic resin which is 120% or more of the resin (A). D2: The difference in solubility parameter from the resin (A) as a base material is within 3 and the elastic modulus is 1 to 50 parts by volume of a thermoplastic resin different from the thermoplastic resin (A) having a crystallinity of less than 120% of (A) and a crystallinity of 40% or more, D3: the resin (A) serving as a base material And a difference in solubility parameter between the resin (A) as a base material and the resin (A), which is at least liquid at extrusion processing temperature, is 3 or more. The organic compound which is at least liquid at the extrusion processing temperature is 1 to 2 0 parts by volume, D5: 1 to 10 parts by volume of at least one filler selected from organic or inorganic having an average particle diameter of 10 μm or less, extruded by a die, and heat transferred. The medium is directly or indirectly quenched and solidified by a medium, and then at a temperature of 15 ° C. or higher and a temperature not higher than the temperature obtained by adding 50 ° C. to the Vicat softening point of the thermoplastic resin (A) constituting the precursor layer, and The film is stretched in at least one direction at an area stretching ratio of at least 2 times and at most 50 times under a temperature condition of a crystal melting point or lower, and a microporous film is obtained by forming microporous in the precursor layer. For producing a fluid-permeable microporous film,

(7) α- crystal having a crystal melting point of 140 to 250 ° C.
99 to 50 parts by volume of a thermoplastic resin (A) mainly containing a copolymer resin of olefin and carbon monoxide and a thermoplastic resin (B) mainly containing a polyolefin resin having a crystal melting point of 80 to 240 ° C. And at least one microporous forming precursor layer comprising a composition comprising 1 to 50 parts by volume of the stretch opening material (D) described in (6) above, is extruded with a multilayer die, and directly or indirectly with a heat transfer medium. At a temperature not lower than 15 ° C. and not higher than the temperature obtained by adding 50 ° C. to the Vicat softening point of the thermoplastic resin (A) constituting the precursor layer, and not higher than the crystal melting point of the resin. In at least one direction, the area stretch ratio is 2 times or more and 50 times or more.
The method for producing a heat-resistant, fluid-permeable microporous film, characterized by obtaining a microporous film by stretching the precursor layer to form a microporous film,

(8) α- having a crystal melting point of 140 to 250 ° C.
A thermoplastic resin (A) containing a copolymer resin of olefin and carbon monoxide as a main component, and / or having a crystal melting point of 80 to 240.
A microporous forming precursor layer composed of a thermoplastic resin (B) containing a polyolefin resin as a main component at a temperature of at least 1 ° C.
An auxiliary layer (S) made of a non-flowable resin composition containing a thermoplastic resin different from the resin forming the precursor layer as a main component of the layer;
Are simultaneously co-extruded with a multilayer die, quenched and solidified directly or indirectly with a heat transfer medium, and then heated to 15 ° C. or higher and 50 ° C. to the Vicat softening point of the thermoplastic resin (A) constituting the precursor layer. At a temperature of not more than the added temperature, and at a temperature not higher than the crystal melting point of the resin, by stretching in at least one direction by an area stretch ratio of 2 times or more and 50 times or less, and then peeling and removing the auxiliary layer, An object of the present invention is to provide a method for producing a heat-resistant and fluid-permeable microporous film characterized by obtaining a microporous film.

Hereinafter, the present invention will be described in detail. In the film of the present invention, at least one thermoplastic resin (A) is used.
The functional layer (abbreviated as MA) which is a continuous phase of the layer and forms a heat-resistant, fluid-permeable, microporous film. The resin has a crystal melting point of 140 to 25.
It consists of a copolymer resin of α-olefin and carbon monoxide at 0 ° C. Specifically, at least one of olefins containing isomers having about C2 to C12 carbon atoms, such as ethylene, propylene, pentene, hexene, octene, etc.
A copolymer of a selected α-olefin and carbon monoxide, wherein the content (mol%) of carbon monoxide is 10 to 5
0 mol%, preferably 20 to 50 mol%, more preferably 30 to 50 mol%.

More preferred are those obtained by copolymerizing ethylene-based propylene and carbon monoxide,
And those obtained by copolymerizing ethylene-based octene-1 in the same manner. Aspects of the copolymerization of the α-olefin and carbon monoxide include those having a random shape, a structure having the random portion as a free block portion in the molecular chain, or those having different α-olefins, Alternatively, a mixture of both, or a portion having a gradient state (so-called tapered shape) in which the copolymerization density of the random copolymerized portion of carbon monoxide is sequentially different in the molecular chain may be taken. it can.

The crystalline melting point (main peak by DSC method) of these copolymers is 140 to 250 ° C., preferably 150 to 250 ° C.
The temperature is 250 ° C, more preferably 160 to 240 ° C, including those having a single peak, a double peak, and other multiple peaks. In the present invention, in the case of a resin having a plurality of peaks or a mixed resin, the melting point as a representative value to be represented is 3 points of the entire peak area (or the same height).
It is expressed as a peak on the high temperature side occupying 0% or more. If the above judgment cannot be made because the peak height and the temperature position are close to each other, the average value is used.

The weight average molecular weight (Mw) is usually 10,0
00 to 500,000, preferably 20,000
0 to 300,000. Next, the above functional layer (M
A) a functional layer (MB) added to co-extrude with A) to exhibit a highly functional synergistic effect as a whole as a whole (for example, to close micropores in a lower temperature region than the MA layer and block fluid permeability). ) Is a polyolefin resin (B) having a crystalline melting point of 80 to 240 ° C.
It is a polymer selected from kinds of α-olefins or a copolymer of α-olefins.

If necessary, at least a part of these aromatic rings may be hydrogenated with vinyl acetate, acrylic acid and its derivatives, aromatic styrene and its derivatives or polymers as copolymerization components other than the α-olefin. Having a structure in which a monomer having a cyclohexane (unsaturated portion) ring, a cyclopentadiene ring, a dicyclopentadiene ring, a norbonene ring, or the like is copolymerized and hydrogenated. Can also be used.

Examples of these are polyethylene resin, polypropylene resin, polybutene-1 resin,
-Methylpentene-1 resin, and a mixed composition thereof.

When the resin layer (MA) and the resin layer (MB) are combined, the difference between the crystal melting points of the resin (B) and the resin (A) is preferably 20 ° C. or more, more preferably 30 ° C.
C. or higher, more preferably 40 ° C. or higher. Further, it is preferable that the crystalline melting point of the resin (B) is lower than that of the resin (A).

Next, the characteristics of the fluid-permeable microporous film of the present invention will be described. (1) The characteristics of the fluid-permeable microporous film comprising the resin (A) unit are as follows: first, the porosity is 30 to 80%;
Preferably it is 40 to 70%. If the porosity is less than the above lower limit, it is difficult to impart practically effective fluid permeability (related to air permeability, electric resistance, etc.), and if the porosity is more than the upper limit, a problem occurs in the strength of the film. Air permeability is 5-2
000 sec / 100 cc, preferably 10 to 1000 sec / 100 cc, more preferably 1 to 1000 sec / 100 cc.
It is 5 to 700 sec / 100 cc.

Below the lower limit, there is a problem in the strength of the film, and above the upper limit, when used as a battery diaphragm,
It is not preferable because the electric resistance is too high and causes a problem when charging and discharging. The 10% shrink temperature is 100 ° C or higher, preferably 110 ° C or higher. Below this lower limit, there is a problem in dimensional stability during use, and particularly when charging and discharging with a secondary battery or the like, an electrode that has an electrolytic solution, is tightly sealed, and is wrapped in the film of the present invention, generates heat. Further, when the film shrinks, there is a danger that the electrode, the active material, and the like are extremely tightened and damaged, and there is a danger that the end of the electrode is exposed and short-circuited.

(2) The characteristics of the fluid-permeable microporous body composed of at least two layers of the resin (A) and the resin (B), which are one of the preferable embodiments of the present invention, are as described above. In addition to having the same properties as the resin (A) single layer of 1), the difference in the crystal melting point of the resin used for either the (MA) layer or the (MB) layer is at least 20 ° C. , Preferably at least 30 ° C, more preferably at least 4 ° C.
It is at 0 ° C. Preferably, a combination in which the melting point of the resin (B) constituting the (MB) layer is lower than the melting point of the resin (A) is selected.

The reason is that when the functional layer made of a resin having a low melting point is used in the above-mentioned secondary battery, for some reason, the electrode may be overcharged, short-circuited with an active material, or dendrite-like crystals generated during charging. When a battery explodes or ignites due to short circuit, runaway reaction, mechanical deformation / destruction phenomenon, etc., and heat is generated, the high melting point resin layer melts and flows, and as a result, the electrode plate does not short circuit. (Before that in time), the communication hole of the resin layer on the low melting point side is closed and the electric resistance is increased to such an extent that current does not flow within a short time, and the current between the electrodes is cut off and insulated. This is because explosion and ignition can be prevented and safety can be ensured.

(3) In a more preferred embodiment, at least two functional layers (MA) including a surface layer of the resin (A) and at least one functional layer (MA) of the resin (B)
The characteristics of at least three layers of the film composed of the functional layer (MB) forming the inner layer of the layer are the same as those of the above-described film, and the crystal of the resin (A) is added to the surface functional layer (MA). By using the higher melting point and using the lower crystalline melting point of the resin (B) for the inner layer, additional characteristics can be obtained.

In particular, when used as a battery diaphragm, a functional layer having a higher melting point resin is disposed on the side in contact with both electrode surfaces having a large thermal capacity, and a low melting point resin is provided inside. By arranging the layers, more favorable effects were obtained.

That is, by arranging the low-melting-point layers on both sides of the porous and uneven electrode surface, when the temperature becomes high, they flow and easily sink into the electrode corresponding to the unevenness of the electrode. Since high pressure is generated and the membrane is damaged, the entire membrane is thinned and short circuit is easily caused, the current interrupting performance is easily deteriorated, and the low melting point functional layer inside the membrane is pressed from both sides. , Than the lateral dimensional change (shrinkage)
This is because the film thickness direction of the low melting point layer is more effectively shrunk and compacted, and the overall resistance is more effectively and sensitively increased, thus exhibiting an excellent effect as a current blocking layer.

It was also found that the short-circuit temperature due to the melting short-circuit of the heat-resistant layer became uniform and shifted to a higher temperature side. Here, the “closed-short circuit” temperature difference is preferably 30 ° C. or more,
It is more preferably at least 40 ° C., even more preferably at least 50 ° C. The lower limit is slightly different depending on the battery constituent material used, but it is better to be as low as possible from the safety of temperature rise as a battery, and it is about 80 to 140 ° C.

The film has a heat resistant dimensional stability which is close to the shrinkage characteristics of the surface layer even if the low melting point layer has a thickness ratio of 70% to all layers despite having a layer having a low melting point and easily shrinking at a lower temperature. In addition, the dimensional stability with heat resistance referred to in the present invention is a biaxially stretched film (in the case of a longitudinally uniaxially stretched film, the two electrodes and the diaphragm are overlapped in the stretching direction, that is, in the longitudinal direction of the flow direction, and formed into a roll. In terms of finishing, there is a feature that it does not shrink in the lateral direction). The diameter of the communication opening for exhibiting the fluid permeability of the fluid-permeable microporous body is 0.01 to 10 μm, preferably 0.02 to 5 μm.

Next, the method for producing the film of the present invention will be described. One method of obtaining the film of the present invention is to extract the thermoplastic resin (A) serving as the base material described above and / or the additional thermoplastic resin (B) and extractable and have a viscosity at 200 ° C. of 1000 CPS or less. The composition for a microporous formation precursor layer containing 85 to 10 parts by volume of the present and inert organic liquid substance (C) as a main component is extruded with a die (in some cases, a multilayer die), and directly or indirectly with a heat transfer medium. At a temperature not lower than 15 ° C. and not higher than the temperature obtained by adding 50 ° C. to the Vicat softening point of the thermoplastic resin (A) constituting the precursor layer, and not higher than the crystal melting point of the resin. In at least one direction, the area stretch ratio is 2 times or more and 50 times or more.
This is a method for producing a microporous film by extracting the above-mentioned substance (C) after stretching it to twice or less.

The base resin which becomes the body of the fluid-permeable microporous film is as described above. The inert liquid substance (C) which is previously mixed with the base resin at the time of production is the same as that of the M layer. (Or the S chosen in the preferred case)
Layer) at least liquid (eg,
1000 poise or less at 200 ° C .: measured with a B-type viscometer) and an average molecular weight of 5000 or less, preferably 3
One or more selected from organic substances having a molecular weight of 000 or less (including monomolecular substances, oligomers and low molecular weight polymers) are used.

The substance (c) may be a surfactant, a plasticizer, a solvent, a lubricant, a wax, or a known substance generally used for producing a microporous film by a phase separation method. For example, liquid at room temperature such as liquid paraffin, paraffin oil including paraffin wax, mineral oil (including paraffin type and saturated cyclonaphthene type), liquid rubber such as liquid polybutene and liquid polybutadiene, etc. Organic liquids, paraffin waxes that are solid at room temperature, higher alcohols, higher alcohol esters, or aliphatic / aromatics including dioctyl phthalate, dioctyl adipate, dioctyl sebacate, dicyclohexyl phthalate, triphenyl phosphate Various esters such as dicarboxylic acid and phosphoric acid Is, it may be a mixture in a single product.

By selecting these amounts and types, the state of phase separation from the base thermoplastic resin changes, and as a result, the porosity, pore structure, pore diameter, etc. of the microporous film can be changed. The addition amount of (c) of the present invention is as follows.
It is 85 to 10 parts by volume with respect to 5 to 90 parts by volume, and preferably 70 to 30 parts by volume with respect to 30 to 70 parts by volume of the base resin.

In addition, an auxiliary layer made of a non-fluid resin composition mainly composed of a thermoplastic resin different from the precursor layer resin added at the time of manufacture (a material which does not become fluid-permeable even when stretched simultaneously) ( And S) are simultaneously co-extruded with a multilayer die, and then the (S) layer is peeled and removed. Then, an inert liquid substance (C) is extracted to obtain a precursor of a microporous film, which is then stretched. (Uniaxially, or preferably biaxially) to obtain the desired fluid-permeable microporous film, or preferably, simultaneously extruding the (S) layer and then simultaneously stretching (same as above), There is a method of obtaining a microporous film by peeling and removing the auxiliary layer and extracting an inert liquid substance (C).

Further, another preferable production method will be described. A microporous forming precursor layer (hereinafter referred to as an M layer) containing the thermoplastic resin (A) or the thermoplastic resin (B) additionally used and a stretchable opening material described below. More preferably, an auxiliary layer (S) made of the above-mentioned or the following non-flow-permeable thermoplastic resin different from the resin used for the M layer whose main purpose is to improve the film-forming properties of at least one layer Layer) and co-extruded (simultaneously) to give a uniform flow orientation (of a high content ratio) in the width and flow directions, quenched and solidified with a heat transfer medium, and then at least 1 at a predetermined range of temperature and stretching ratio. There is a method of obtaining a microporous film by stretching in the direction to form a microporous film to obtain a multilayer film, and then peeling and removing the S layer (in some cases, collecting and recycling).

In this method, a microporous forming precursor layer (MA and / or additional MB) composed of a composition containing as a main component a thermoplastic resin forming at least one continuous phase;
Further, at least one layer of a non-flow-permeable auxiliary layer (S) mainly composed of a thermoplastic resin different from the resin used for the precursor layer was laminated and co-extruded with a multilayer die. After the appropriate flow orientation has been added, the precursor layer is quenched and solidified directly or indirectly by a heat transfer medium to form
Under a temperature condition of not less than 50 ° C. and not more than a temperature obtained by adding 50 ° C. to the Vicat softening point of the composition constituting the precursor layer, the obtained laminate was obtained in an area magnification of 1.1 to 30 in at least one direction.
A multi-layer film in which microporosity is formed in the precursor layer is obtained by stretching the film up to twice or less, and the auxiliary layer (S) is peeled off to obtain a fluid-permeable microporous film.

According to this method, it is possible to impart a uniform and high flow orientation, which was impossible with the M layer alone,
During the stretching process, which was a drawback of the conventional method, it became uneven and teared, or the hole shape and characteristics differed in the thickness direction,
The problem of lack of uniformity in the width direction has been solved.
Moreover, the stretching by the bubble method which is more strictly conditional (particularly,
Conventionally, there is a problem of puncturing or non-uniformity due to the above reasons when adding a high stretch orientation of high magnification at a low temperature in the vertical and horizontal simultaneous directions or when obtaining an ultrathin wall, for example, a target film of about 2 to 5 μm. Yes, there is a problem that the air in the bubble escapes and cannot be enclosed, and stretching cannot be continued.) It has become possible to efficiently produce a microporous film.

In the present invention, the M layer comprises the thermoplastic resin (A) forming a fluid-permeable microporous body forming at least one continuous phase and / or the additional thermoplastic resin (B). It consists of a layer of the composition as the main component. As such a thermoplastic resin (A) or (B), the same resin as the above-mentioned film is selected as a relatively hard resin from the viewpoint of imparting strength by stretching orientation and forming stable holes. You.

The thermoplastic resin (A) and / or (B) for determining the pore diameter of the finally obtained microporous film of the present invention.
In order to control the state of dispersion in the resin by mixing different kinds of stretch opening burrs that become a disperse phase, the amount of the thermoplastic resin (A or B) that becomes a continuous phase is reduced to 99 to 55% by volume. , Preferably 98 to 60% by volume, more preferably 97% by volume.
７０70% by volume. The following (D1) which forms a dispersed phase and becomes a stretchable openable substance (D) under the processing conditions of the present invention:
At least one substance (D) selected from (D5)
Is used in an amount of 1 to 45% by volume, preferably 2 to 40% by volume, more preferably 3 to 30% by volume. When the amount of (D) is less than the above lower limit, an effective stretching opening effect cannot be exhibited, and when it is more than the above upper limit, the properties of the substrate are denatured (reduced strength, uneven opening, etc.). It is not preferable.

As (D1) to (D5), the following are used from the viewpoint of characteristics and effects. D1: Solubility parameter with the thermoplastic resin (A) (hereinafter referred to as SP value: polymer blend 12 by Saburo Akiyama et al.)
Pages 5 to (1981, published by CMC) and the Journal of Journal by Small.
Applied Chemistry Volume 3 71
(1953). If the calculation cannot be performed by this method, the difference between the polymers in the solvent (estimated by the solubility in the SP value) is within 3 and the flexural modulus (refers to the flexural modulus according to ASTM D790 in the present invention). Is 140% or more of the thermoplastic resin (A).

D2: Thermoplastic resin (A) having a difference in SP value from thermoplastic resin (A) of 3 or less, an elastic modulus of less than 140% of thermoplastic resin (A) and a crystallinity of 40% or more. A) a different thermoplastic resin. D3: An organic compound having a solubility parameter difference of at least 3 with respect to the resin (A) as a base material and being at least liquid at an extrusion processing temperature. D4: Organic substance having a difference in SP value from the thermoplastic resin (A) within 3 and being liquid at a temperature at which the M layer is melt-extruded. D5: Organic or inorganic filler having an average particle diameter of 10 μm or less.

Preferably, two or more of these (D) are used in combination. These stretch-openable substances (D) are basically mixed with the thermoplastic resins A and / or B constituting the base material at least at the softening point of the resin (Bichat softening point) or at the crystal melting point or lower. Those that are not completely compatible (in a molecularly dispersed state) are selected. Preferably, those which are finely dispersed uniformly in a controlled shape and are stable over time are preferred. It is preferable to select at least one component from the openable thermoplastic resin (D1) or (D2) as the component (D) in order to reduce the deterioration of the properties of the base material, and to add another openable substance to them. In some cases, a synergistic effect can be expected.

The openable thermoplastic resin (D1) has a suitable affinity for the thermoplastic resins (A) and (B) of the base material, and is dispersed into a given particle size and shape by melt-kneading and dispersing. It is stable after cooling and solidifying, and is capable of uniformly separating the interface with the base thermoplastic resin under stretching conditions, and is a resin having a higher flexural modulus than the base, Preferably, it has a lower molecular weight than the substrate.

The openable thermoplastic resin (D2) has an appropriate affinity for the thermoplastic resins (A) and (B) of the base material, and is dispersed into a certain particle size and shape by kneading, dispersing and stretching. It is stable after cooling and solidification, is crystalline, and can make the interface with the base material easier to peel off.

On the other hand, there is no appropriate affinity with the thermoplastic resin of the base material, that is, the difference in SP value between the thermoplastic resin (D1) or the thermoplastic resin (D2) and the thermoplastic resin of the base material is 3
When it exceeds, the dispersion state is not constant even when kneaded, and as a result, the strength is liable to decrease, and a uniform microporous film cannot be obtained. In addition, when the difference in SP value is within 3 and is relatively soft (less than the elastic modulus of 140%) and low in crystallinity as compared with the base resin, the hole is not uniformly opened in the subsequent stretching step. There is.

The stretch openable substance (D3) is formed of S with the base resin.
P value difference is 3 or more and at least liquid at the temperature at which the M layer (S layer) is melt-extruded (for example, 1000 poise or less at 200 ° C .: measured with a B-type viscometer), and generally has an average molecular weight of 5000 or less, preferably Is selected from organic substances having the same molecular weight of 3000 or less (including oligomers and low molecular weight polymers).

Examples of these are silicone oils having low polarity and modified products thereof, and fluorine oils and modified products thereof. Conversely, those having high polarity and high hydrophilicity can also be used. In short, it is only necessary that the selected base resin and the SP value are apart from each other.

The stretch-openable substance (D4) is made of S
P value difference is within 3 and at least liquid at the temperature at which the M layer (S layer) is melt-extruded (for example, 1000 poise or less at 200 ° C .: measured with a B-type viscometer), and generally has an average molecular weight of 5,000 or less, preferably Is an organic substance having the same molecular weight of 3000 or less (including oligomers and low molecular weight polymers)
It was chosen from

Examples of these include surfactants, plasticizers, solvents, lubricants, waxes, and those generally used when producing microporous films by a phase separation method. For example, known dioctyl phthalate (SP value: 8.7), dioctyl sebacate (SP value: 7.
9), esters of aliphatic / aromatic dicarboxylic acids and phosphoric acids such as dicyclohexyl phthalate (SP value 8.6), triphenyl phosphate (SP value 8.6), liquid paraffin and paraffin wax. Paraffin oil, mineral oil (paraffin type,
Organic liquids that are liquid at room temperature, such as liquid rubbers, including saturated cyclonaphthenes, liquid polybutene and liquid polybutadiene, paraffin wax that is solid at room temperature, higher alcohols, rosins, terpene resins and their hydrogenation Products, petroleum resins and hydrogenated products thereof. When these are used, the microphase separation state between the obtained base thermoplastic resin and the opening substance (D4) changes, and the pore diameter of the microporous film may change, so that they are selected and used.

The difference in SP value between each component of the substance (D4) and the thermoplastic resin forming the base material is within 3 as in the case of the openable thermoplastic resins (D1) and (D2). If it exceeds this range, even if the kneading is sufficiently performed, the fine particles are not uniformly dispersed, separated and aggregated, and as a result, a uniform microporous film may not be obtained.

The stretch opening material (D5) is an organic or inorganic filler having a particle size (average particle size measured by a three-dimensional projection method) of 10 μm or less. As these fillers (D5), organic or inorganic fillers generally used for rubber or resin are used.

For example, examples of the organic filler include cellulose-based powder, styrene-based, acrylic-based, silicone-based, silicone-acryl-based, and other resin-based crosslinked fine particles. Further, as the inorganic filler, for example,
Calcium carbonate, clay, kaolin, silica (including spherical), diatomaceous earth, magnesium carbonate, barium carbonate, aluminum oxide, zinc oxide, magnesium hydroxide, magnesium oxide, titanium oxide, alumina, glass powder, zeolite, carbon, activated carbon fine particles, graphite System fine particles and the like are used. These may be used singly or in combination depending on the required final pore diameter and stretching conditions.

When the above filler (D5) is used, in order to improve the dispersibility of the filler in the thermoplastic resin (A), known fillers such as a surfactant, a plasticizer, a lubricant, and a silicone-based dispersing agent may be used. Auxiliaries can be used.

Incidentally, a plurality of substances (D5) may be used for the thermoplastic resin as the base material. Further, for the purpose of improving the stretchability at the time of production, the tensile strength, the tear strength, the pore size distribution, and the like of the obtained microporous film, the crystal nucleating agent is preferably added in the range of 0.05 to 30% by volume based on the whole. Known modifiers such as compatibilizers, soft resins, and elastomers, additives, and processing aids may be used.

The thermoplastic resin serving as the base material used in the present invention and the precursor layer (M layer) composed of the above-mentioned additives are used to form the microporous film to be obtained with strength, heat resistance, and pore size distribution in the thickness direction. Depending on performance requirements, it has at least two or more layers as functional layers, and when each layer is of the same type, the composition is different in the mixing ratio of the mixed composition, or the microporous state of different pore structures composed of layers composed of different resin compositions It is also preferable to take a multilayer structure having

The breakdown of the multi-layered functional layer (M layer) is a multilayer composed of those having different copolymerization ratios and molecular weights among the base resin (A) of the functional layer MA. The functional layer MB to be added is also a mixture of the base resins (B) or a mixture of both (A, B).

The thermoplastic resin (E) constituting the auxiliary layer (S layer) used in the present invention is not particularly limited as long as it improves the film formability and stretchability of the M layer. In order that the M layer and the S layer can be easily separated, the difference in solubility parameter between the thermoplastic resin (A) constituting the M layer adjacent to the S layer is preferably 0.3 or more.

Specifically, it is not the same as the type of the resin forming the adjacent M layer, and is a polyolefin resin,
It is preferable to use either a polyamide resin or a polyester resin as a main component. Among them, as the polyolefin-based resin, a resin mainly composed of a low-density polyethylene-based resin, a polypropylene-based resin, a polybutene-1-based resin, an ionomer-based resin, or the like (50 vol% or more) is used.

Preferably, a crystalline resin mainly composed of polybutene-1 and a petroleum resin are added to
30% by weight of a composition, and / or a ternary composition in which a polypropylene resin is mixed in an amount of 5 to 90% by weight of the total composition, or 5 to 30% by weight of a polypropylene resin and a petroleum resin. The composition, the copolymerized polyester resin, or the following (E1), (E2) and (E
It is a resin composition composed of the resin composition composed of (E1) and (E2), or a resin composition composed of (E2) and (E3).

<Component (E1)> As the component (E1),
Mainly from the viewpoint of stretchability, a polymer having a relatively low crystallinity (35 to 75%, preferably 40 to 70% crystallinity by a DSC method) of an intermediate level between hard and soft is selected. Examples of such a polymer include low-density polyethylene of the ethylene copolymer group, preferably linear low-density polyethylene (LLDPE), and ultra-low-density polyethylene (V
LDPE) and other known new catalysts such as copolymers of ethylene and C3 to C12 α-olefins having an α-olefin content of 15 mol% or less and a VSP of 80 ° C. or more, and single-site catalysts including metallocenes. And the like.

Of these low-density polyethylenes, linear low-density polyethylene (LLD) which is a preferred example
PE) is obtained by adding propylene, butene, pentene, hexene, heptene, octene, 4-methyl-1- to ethylene obtained by the medium pressure method, the low pressure method, or, in some cases, the high pressure method.
At least one olefin selected from C3-C12 α-olefins such as pentene is copolymerized in an amount of 10 mol% or less, preferably 1.5 to 9 mol%.

The MI of these resins is selected from the viewpoints of stretchability, dispersibility with other components to be mixed, and prevention of disorder between other layers.
Usually, it is 0.2 to 15, preferably 0.2 to 10.
The VSP of these resins is 80 ° C. or higher, preferably
85 ° C or higher. The carbon number of the preferred α-olefin of the comonomer is C5 to C12 from the viewpoint of the film strength (for enhancing the drawing assisting ability of the auxiliary layer).

The group having a polar functional group includes a copolymer of ethylene and at least one monomer selected from vinyl ester monomers, aliphatic unsaturated monocarboxylic acids, and alkyl monocarboxylate derivatives. And at least one polymer selected from ethylene-styrene copolymers of 99 to 82 mol% of ethylene and 1 to 18 mol% of styrene, or derivatives thereof.

More preferably, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-acrylic acid copolymer (EMA), ethylene-methacrylic acid copolymer (EM
A). Further, these include those in which the alkyl group of the alcohol component of ethylene and the unsaturated monocarboxylic acid alkyl ester has C2 to C12, preferably C2 to C8 (for example, propyl, butyl, hexyl, octyl, etc.). ) Or at least two of the above
Also included are multi-component copolymers selected from species of monomers, or polymers in which at least a part thereof has a saponified carboxyl group and at least a part of which is ionized (ionomer resin).

The amount of the monomers other than ethylene in these copolymers is preferably 1.5 to 12 mol%, more preferably 2 to 10 mol%. When this amount is 1.5 mol% or more, flexibility, strength characteristics and the like are excellent. On the other hand, if the amount exceeds 12 mol%, the extrusion processability, the mixing property with other components, etc. are deteriorated, and when used as a surface layer (outermost layer), the surfaces are blocked from each other, causing a problem in handling. come.

The MI of these resins is usually 0.2 to 10
And preferably 0.3 to 5. When the MI is less than 0.2, there is a problem in the mixing properties and extrudability of the raw materials, and when the MI exceeds 10, turbulence between the layers with the M layer is liable to be caused during multilayer extrusion, and the strength as the S layer is insufficient. For example, it is not preferable because it is easily broken at the time of stretching.

<Component (E2)> The component (E2) is a soft, thermoplastic elastomer having a VSP of 80 ° C. or less, and α
-Olefinic elastomers, i.e. different α-
Copolymer of two or more olefins (C3 to C1)
2) or ethylene and an α-olefin copolymer having C3 to C12, a butyl rubber-based elastomer, a styrene-conjugated double bond diene derivative block copolymer elastomer, and at least a portion derived from a conjugated double bond or a ring of the elastomer. A copolymer obtained by hydrogenating 1 part, a copolymer containing 20 to 80 mol% of an α-olefin and 80 to 20 mol% of styrene (including at least one part of an aromatic ring portion hydrogenated), At least one polymer selected from thermoplastic polyurethane and the like is preferred. Further, a graft-modified resin of these resins may be used.

The density of these α-olefin elastomer copolymers is 0.860 to 0.905 g / cm ³ , preferably 0.865 to 0.900 g / cm ³ . V of these α-olefin elastomer copolymers
SP is preferably 75 ° C. or less, more preferably 70 ° C.
Below, more preferably, it is 60 degrees C or less. These α
-The olefin elastomer copolymer generally includes those having a degree of crystallinity of about 30% or less from a substantially amorphous substance in a rubbery region, and the degree of crystallinity is preferably 20% or less,
More preferably, 15% or less, more preferably, 10%
It is of the following low degree of partial crystallinity. The melting point of the crystal is usually preferably 120 ° C. or lower, more preferably 110 ° C. or lower, and still more preferably 100 ° C. or lower, as measured by a DSC method (heating rate at 10 ° C./min). .

Preferred among the α-olefin elastomer copolymers are ethylene and propylene or butene-
1, a copolymer of propylene with butene-1 or 4-methylpentene-1 or a mixture thereof, for example, a random or block (co) polymer polymerized with a single-site or metallocene catalyst, or a vanadium-based polymer And a random copolymer polymerized with a compound and an organoaluminum compound-based catalyst. Then, MI (ASTM method D1)
(Measured according to the E condition of 238: hereinafter simply referred to as MI) is 0.1 to 10, preferably 0.2 to 6.

<Component (E3)> The component (E3) is a component that is relatively hard [harder than the components (E1) and (E2)] and has a relatively high crystallinity, and is composed of polypropylene, (high molecular weight) polybutene. -1, high density polyethylene, poly 4-methylpentene-1, (hereinafter IPP, PB-
1, abbreviated as HDPE, PMT) or a free copolymer. These can be used as such when used alone or as a component (E) when used as a mixture.
3) The overall VSP is 80 ° C. or higher, preferably 90 ° C.
It is preferably made of a relatively hard polymer having a temperature of 100 ° C or higher, more preferably 100 ° C or higher.

Melt flow rate of PP [ASTM D
Measured at 1238 (L condition). Hereinafter abbreviated as MFR] is usually 0.1 to 30, preferably 0.5 to 20, and more preferably 0.7 to 15. When the MFR is less than the above, there is a problem in mixing properties (uniformity) during processing, and when the amount is larger than the above, there is a problem in extrusion stability.

As PB-1, the content of butene 1 is 90
A copolymer with another monomer (for example, ethylene, propylene, C5 or more) having a crystallinity of mol% or more can be included. The MI is preferably about 0.1 to 10 and a hydrogenated saturated hydrocarbon resin may be mixed and used in an amount of 2 to 20% by weight.

Further, one of IPP and PB-1, or a mixture of both, is added to a hydrogenated saturated hydrocarbon resin (preferably,
It is preferable to use a composition in which one component of the constituent unit contains the same resin containing at least a part of a cyclic portion). In addition, other than the above, any hard polymer having appropriate compatibility and dispersibility can be used.

As the PMT, the melt flow rate (M
FR) (a value measured at 260 ° C. and a load of 5 kg according to ASTM method D1238) of about 1 to 200, and a 4-methylpentene-1 content of 85 mol% or more,
Those which are crystalline and contain a copolymer with at least one other α-olefin monomer are preferred. Further, these polymers and copolymers can be used by mixing with each other at a free ratio. Further, the above-mentioned IPP, PB-1 or other known resins may be mixed and used within a range not exceeding 50% by weight. This amount is preferably not more than 40% by weight, and more preferably not more than 30% by weight.

Preferred combinations of the above components in the auxiliary layer (S layer) used in producing the fluid-permeable microporous film of the present invention are (E1), (E2), and (E1).
2) and (E3) and (E1), (E2) and (E3)
And a mixed composition mainly composed of

The preferred range of the mixing amount of each component is as follows. 0.05 ≦ E2 / (E1 + E2) ≦ 0.90, 0.30 ≦ E2 / (E2 + E3) ≦ 0.90, 0.05 ≦ E2 / (E1 + E2) ≦ 0.90 and 0.05 ≦ E3 / ( E1 + E2) ≦ 2.0

When the mixing amount of the soft component (E2) is small, the synergistic effect of the mixture is hardly exhibited in each case, and for example, the effect of improving the stretchability by the S layer is reduced. Also, if the mixing amount of (E2) is too large, the film becomes too soft, and the stretch orientation cannot be sufficiently imparted to the M layer. By selecting the component (E2) from a preferable weight range, the synergistic effect as a mixture is increased even in the case of (1), and various properties are improved, and for example, the film strength, stretchability, and the like are improved step by step.

Among the above-mentioned combinations of mixed compositions, particularly preferred combinations are mainly composed of (E1), (E2) and (E3). In this case, the component (E3) has a large effect of synergistically improving the extrudability and stretchability of the mixed composition with other components. Of the three components, component (E1) and component (E3)
In the case of only mixing, the mixing and compatibility are usually not satisfactory, and it is difficult to expect the above-mentioned synergistic effect. However, when the component (E2) is added, those drawbacks are remarkably improved, and In many cases, the stretchability and the effect of assisting the stretching to other layers are also improved.

The S layer is a layer to which other known resins are added so that the characteristics of the mixed polymer are at least 50% by weight, preferably 80% by weight or more without impairing various properties. May be. This S layer has not only good drawdown properties and stretchability itself, but also
Exhibits a remarkably high drawdown property (such as non-uniformity and breakage in the M layer alone) and high uniformity (no vertical or horizontal thickness unevenness) in the M layer, which is exhibited when a multilayer is formed. In addition, the raw material puncture and the stretch puncture are prevented, and the stretchability of the M layer and the porosity by stretching are greatly improved.

Further, there is an effect of preventing necking from occurring in the precursor layer during stretching. Furthermore, during co-stretching, there is an appropriate interlayer adhesion force, and the stretching as a whole due to the difference in the resin constituting both layers (strain generated due to different stretching conditions in a single layer) does not occur. The optimum stretching conditions are widened, and a synergistic effect is achieved that is more stable as a whole. As a result, the stretching characteristics of the entire layer are improved, and the amount of the opening material used may be smaller, and even if the opening material is particularly small in a dispersed state, the opening material can be effectively opened and the fluid permeability can be improved. The uniformity of the film, the control of the pore size and its distribution, the porosity, etc. are improved. Particularly, the strength is remarkably improved by stretching the M layer finally used as the microporous film.

In the case of stretching the M layer alone, even under the condition that the area stretching ratio is only up to 2 times in the non-uniform stretching, it is possible to perform uniform stretching to a higher ratio by laminating with the S layer, In addition, stretching can be performed even at low temperature conditions (10 to 30 ° C.) (particularly, simultaneous biaxial stretching), which cannot be stretched at all (for example, breaks) by the M layer alone. Surprisingly, as a synergistic effect, even if the amount of the opening material is set to a small amount (for example, several VOL%) that does not open at all in the case of ordinary single-layer stretching, it is difficult to open the material. However, an opening capable of exhibiting minute and uniform fluid permeability can be obtained. Therefore, it is possible to obtain a fluid-permeable microporous film in the biaxial cold stretching region, which has not been achieved conventionally, and to increase the porosity etc. by controlling the pore size while maintaining the strength by high orientation. Now you can do it.

In order to enhance the releasability from the M layer or the adhesion during stretching at the same time, the thermoplastic resin (E) constituting the S layer
Preferably contains an additive capable of bleeding up to the interface with the M layer. Examples of such additives include:
Nonionic surfactants, for example, esters of fatty acids and polyhydric alcohols, polyoxyethylene alkyl ethers, or higher alcohols, fatty acid amides, waxes, fluorine-based / silicon-based additives, and other special Those which have a function and fit individual purposes can be mentioned.

Among these, those mainly composed of components that are liquid at least at 50 ° C. are preferred. More preferably, after the M layer and the S layer are co-extruded and stretched,
It bleeds at the interface with the layer, and it can easily co-stretch and peel off the two layers while maintaining appropriate adhesion between the two layers. At the same time, it prevents static electricity generation and protects the functional layer. Can also be done. In addition, this makes it possible to prevent aging, breakage at high speed even on-line, and not only a thick film but also an extremely thin film (for example, 1 to 1).
(0 μm) can be peeled and wound up.

The bleedable additive may be applied to the M layer or to both layers depending on the case. Usually, the amount of these additives is preferably from 0.2 to 5% by weight. If the amount is less than 0.2% by weight, the effect of facilitating peeling cannot be sufficiently obtained. If the amount is more than 10% by weight, appropriate adhesion between the two layers is not maintained, and the layers are displaced during stretching and peeled off.

The preferred overall layer structure including the M layer and the S layer is M layer / S layer, M layer / S layer / M layer, S layer /
M layer / S layer, M layer / S layer / M layer / S layer / M layer, and the like. A layer configuration including a plurality of M layers is desirable in terms of productivity.

Further, as described above, each of the M layer and the S layer may have a multilayer structure. Particularly, when priority is given to high performance and high quality of the microporous film, it is preferable that
Layer / M1 layer / M2 layer, S layer / M1 layer / M2 layer / S layer, S
Layer / M1 layer / M2 layer / M1 layer, S layer / M1 layer / M2 layer /
M1 layer / S layer, M1 layer / M2 layer / M1 layer / S layer / M1 layer / M2 layer / M1 layer.

The thickness of all layers before stretching, including the M layer and the S layer, is preferably 5 to 1000 μm, more preferably
10 to 700 μ. The lower limit of this thickness is determined by the crystal size in the M layer and the dispersion diameter of the B component contained in the M layer. The upper limit of this thickness is extruded, during quenching after imparting flow orientation, or during stretching. It is determined by temperature unevenness during heating and / or cooling.

The ratio of the S layer to the total layer thickness is 10 to 9
0%, preferably 20-80%, more preferably 30-80%
70%. In the above range, the (cold) stretching force of the S layer makes it impossible to perform cold stretching by itself on the functional layer itself, and therefore, the resin layer that cannot achieve the opening can be strongly and uniformly stretched. (Low temperature, high magnification region), and the stretch opening of the layer can be achieved particularly stably (without film breakage and surging). As a result, the synergistic effect of the present invention (high strength, low stretching ratio) Stably opening, expanding the type of opening material used, reducing the amount of use, etc.).

The same effect is observed in the high temperature stretching region. 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 not easily opened by cold stretching, the lower limit of the S layer ratio is relatively high in the entire layer, and conversely, the composition having a composition that is easily opened in a target hole structure is obtained. When a layer is included, the ratio level of the S layer may be low in processing.

In the present invention, preferably, a composition mainly comprising a thermoplastic resin constituting at least one M layer, and further comprising a thermoplastic resin mainly constituting at least one S layer. The compositions are thermoplastically melted by separate extruders, co-extruded from a multilayer die, and quenched and solidified by a heat transfer medium to form a sufficiently uniform tube or sheet material. Examples of the co-extrusion method include a multilayer T-die method and a multilayer annular die method, and the latter method is preferable in terms of raw material efficiency, uniform flow orientation, and the like.

Next, the raw material consisting of the M layer and the S layer is 1
5 ° C or higher, VSP of the above-mentioned thermoplastic resin (A) constituting the M layer is stretched to 1.1 to 50 times in area ratio in at least one direction under a temperature condition of 50 ° C or lower to reduce the microporous or precursor state. Let it form. The opening action and the high orientation are uniformly applied to the M layer by the presence of the S layer at the time of stretching,
Fine separation occurs between two different phases in the M layer, for example, between the crystal nucleus of the thermoplastic resin (A) and its surrounding domain, or between the thermoplastic resin (A) and the substance (B). It is the source of microporosity. Therefore, a portion that is locally opened and has low strength (pulling or tearing) is less likely to be further uneven.

If the stretching temperature is not higher than 15 ° C. and not higher than the temperature obtained by adding 50 ° C. to the VSP of the thermoplastic resin (A), there occurs a problem that uneven stretching occurs or holes are not formed. I do. When the stretching ratio is out of the above range, for example, less than 1.1 times, the M layer does not uniformly or not at all. On the other hand, when the stretching ratio exceeds 50 times, a phenomenon occurs that the raw material cannot be stretched stably and sometimes breaks. The stretching direction is determined by the composition of the M layer and the properties required for the microporous film, and may be uniaxial or biaxial, but the latter is preferred.

Various stretching methods such as a roll stretching method, a tenter frame method, and a tubular method (including a multi-bubble process such as a double bubble and a triple bubble) are used. The tubular method is used for the following reasons. It is more preferable that at least one S layer is disposed thereon. 1) As described above, it is preferable to manufacture the raw material in a tube shape. 2) Uniformity in the thickness direction, width direction, and length direction of the obtained microporous film and high flow orientation are imparted, so that opening is facilitated. 3) Good uniformity of pore size and pore distribution. 4) There is no loss of product due to the chuck portion or neck-in during stretching. 5) There is no fear of air leakage due to the existence of the S layer having no holes. 6) The S layer protects the M layer from scratches and contamination (fungi, dirt, etc.).

The stretching conditions are as follows: (1) more surely form microporous material during stretching; (2) adapt the microporous properties of the resulting microporous film to the intended use; and (3) ensure dimensional stability. (4) Converting the vertical / horizontal stretching degree
It can be performed in multiple stages for the purpose of moving. Further, the total area magnification may be 1.1 to 50 times at a temperature of 15 ° C. or higher and a temperature not higher than the temperature obtained by adding 50 ° C. to the VSP of the resin (A) constituting the M layer.
It is preferable that the temperature difference at the stretching start part in each stage is at least 5 ° C. or more. Further, it is preferable that the stretching start temperature is raised by at least about 5 ° C. in the later stages of the multistage.

Similarly, it is convenient to perform stretching under the condition that the temperature difference between the stretching start portion and the stretching end portion is 5 ° C. or more. Here, the stretching temperature refers to the temperature of the stretching start portion. When dimensional stability is particularly important, the heat setting effect may be imparted by increasing the temperature of the final stretching step, or a heat setting step may be added as the next step.

Further, prior to stretching, the stretchability of the layered raw material composed of the M layer and the S layer, the stretch opening property of the M layer, and the strength, heat resistance, and dimensional stability of the microporous film are improved. ,
Before stretching, or after stretching M layer, S layer 2-15Mrad,
The cross-linking treatment can be performed preferably by a high energy ray of 2.5 to 10 Mrad. As this method, ionizing radiation, for example, an electron beam, a method of irradiating a β-ray emitted from a radioisotope, a γ-ray, or a sensitizer such as benzophenone or peroxide previously mixed in the M layer, A method of irradiating ultraviolet rays may be mentioned, but it is preferable to use a high energy electron beam industrially.

Further, depending on the purpose, the type of resin, control of molecular weight, additives (promoting or suppressing crosslinking), and the like can be used for the degree of crosslinking of the predetermined layer of the multilayer M layer.
Control by controlling the penetration depth of energy rays (for example, increase the cross-linking density of the surface layer, lower the cross-linking density of the intermediate layer, or perform weak cross-linking such that the gel fraction cannot be measured substantially). Is also good. Further, these crosslinking treatments may be applied to the S layer to obtain a synergistic effect.

By peeling the S layer from the stretched laminate of the M layer and the S layer stretched after the lamination, at least one microporous film is obtained. The thickness of this microporous film is preferably about 1 to 150 μm, more preferably about 5 μm.
About 100 μm. The stretched laminate may have a built-in stretching strain. To remove the strain, the stretched laminate is kept in a tensioned state or a relaxed state (shrinked) after stretching,
Stabilization can be achieved by heating at a predetermined temperature, usually around a stretching temperature (the highest temperature in the case of stretching in multiple stages).

In some cases, a slight (free-direction) uniaxial stretching may be performed at the end to perform the orientation moving treatment. The heating time for removing the strain is set according to the temperature, the amount of strain remaining in the laminate, and the like, and is usually about 5 seconds to 2 minutes. If necessary, this heat treatment may be performed on the microporous film after peeling. The S layer removed from the stretched laminate by peeling may be recycled and used as at least a part of the S layer, or may be mixed with the M layer in some cases.

[0110]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the embodiments of the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

Note that the air permeability shown in the examples is AS
It is a value converted to 25 microns by the Gurley value (sec / 100 cc) measured based on the TM D-726 (B) method. The crystal melting point was determined by annealing the raw material resin at the respective optimum temperature to obtain an equilibrium state.
The values measured at a scan speed of / min are shown. For the porosity, a predetermined film is cut into a size of 10 cm × 10 cm, the average thickness is measured with a thickness gauge, the volume of the sample is determined, and then the weight of the sample is measured. The resin volume integrated in terms of the average density is obtained, and the value obtained by converting (1−resin volume of sample / sample volume) is used.

The Vicat softening point (abbreviated to VSP) is A
The value measured according to STM-D1525 (measured at a heating rate of 2 ° C./min with a load of 1 kg) is used. 10% shrinkage temperature is 10cm x 1 for film sample
Cut to 0 cm, dusted with talc or other powder to prevent adhesion, placed horizontally in an air oven type constant temperature oven heated to a predetermined temperature, and treated for 10 minutes in a freely shrinkable state. Is calculated, and the measured shrinkage value at each temperature is graphed to indicate the temperature at which the shrinkage is 10%.

(Resins and Other Raw Materials Used in Examples) 1) Thermoplastic resin (A) of base material [copolymer resin of α-olefin and carbon monoxide] (A-1): ethylene Part propylene) was copolymerized with 42 mol% of carbon monoxide to 58 mol% (crystal melting point: 212).
° C, melt flow index (measured at a load of 240 ° C-5 kg): 7, VSP: 190 ° C, SP value: 11.
1) Copolymer resin. (A-2): ethylene (partially propylene, octene-
1) A copolymer resin obtained by copolymerizing 62 mol% of carbon monoxide with 38 mol% (crystal melting point: 185 ° C., melt flow rate (under the same conditions as above): 18, VSP: 165 ° C., SP value: 11.0).

(A-3): 65% by weight of A-1 described above
Crystalline polypropylene (abbreviated as PP-1, density 0.90
g / cm ³ , melt flow rate: 6, crystal melting point: 16
0 ° C, VSP: 143 ° C, SP value: 7.6) 35 wt%
%, A composition kneaded with a twin-screw kneader and pelletized. (A-4): A-2 80 wt%, high density polyethylene (abbreviated as HDPE-1, density 0.963 g / cm ³ ,
Melt flow rate: 1.2, VSP: 120 ° C, crystal melting point: 133 ° C, SP value: 8.1) 20 wt% (A-
A composition mixed as in 3).

2) Thermoplastic resin of base material (B) [crystalline polyolefin resin] (B-1): High-density polyethylene (abbreviated as HDPE-1, density 0.963 g / cm ³ , melt flow rate:
1.2, VSP: 120 ° C, crystal melting point: 133 ° C, SP
(Value: 8.1) (B-2): crystalline polypropylene (abbreviated as PP-1)
Density 0.91 g / cm ³ , melt flow rate: 2.
3. Crystal melting point: 163 ° C, VSP: 148 ° C, SP value:
7.6)

(B-3): Polybutene-1 (abbreviated as PB-1, density 0.906 g / cm ³ , melt flow rate: 1.0, crystal melting point 123 ° C., VSP: 106 ° C., S
(P value: 8.3) (B-4): Poly 4-methylpentene-1 copolymer resin (abbreviated as PMP-1, density 0.88 g / cm ³ , melt flow rate: 4.0, crystal melting point: 177 ° C, VSP:
(158 ° C, SP value: 7.3) (B-5): Low density polyethylene (abbreviated as LL1, density 0.923 g / cm ³ , MI 0.8, crystal melting point 118)
° C, VSP100 ° C, SP value: 7.8)

3) Inert organic liquid substance (C) [substance extracted after phase separation from base resin] (C-1): mineral oil (MO-1: paraffin type, viscosity measured by B-type viscometer) Is 30 centipoise at 50 ° C:
Hereinafter, under the same conditions, abbreviated as CPS, SP value: 8.2) (C-2): octyl phthalate (the same viscosity is 15
CPS, SP value: 7.9)

4) Stretching openable substance (D) [mixed and dispersed in a base resin and opened during stretching] (D1-1): polyphenylene ether (PPE: density 1.06 g / cm ³ , melt flow rate 15, Flexural modulus 250 kg / mm ² , SP value 9.6) (D1-2): Styrene-butyl acrylate copolymer (SBA: density 1.05 g / cm ³ , VSP 82 ° C., flexural modulus 185 kg / mm ² , SP Value 8.9) (D2-1): polybutene-1 (PB-1: density 0.9)
07 g / cm ³ , melt flow rate 1.0, flexural modulus 65 kg / mm ² , crystallinity 46%, SP value 8.3) (D3-1): methyl silicone oil (SO-1:
(Viscosity 10 CPS, SP value 5.7)

(D4-1): Liquid paraffin (PA-
1: viscosity 13 CPS, SP value 8.4) (D4-2): hydrogenated petroleum resin (PR-1: VSP130)
° C, viscosity (200 ° C) 800 CPS, SP value: 8.3) (D5-1): crosslinked silicone powder (CSP-1: average particle size 0.5 µm) (D5-2): spherical silica (SFC-1: Average particle size 0.
35 μm)

5) Auxiliary layer (S) (S1): Polypropylene copolymerized with 3% by weight of ethylene (PP1: density 0.90 g / cm ³ , VSP143)
° C, crystalline melting point 152 ° C, MFR 1.5) 75% by weight,
Polybutene 1 (PB) copolymerized with 2% by weight of propylene
1: Density 0.90 g / cm ³ , VSP 98 ° C, MFR
2.0) 10% by weight of hydrogenated saturated hydrocarbon resin (H
1: a so-called hydrogenated petroleum resin having a cyclic portion in the copolymer component, and having a ring-ball method softening point of 150 ° C)
A composition in which 15% by weight is kneaded.

(S2): Polybutene 1 obtained by copolymerizing 3% by weight of ethylene (PB2: density 0.90 g / cm ³ , VS
P90 ° C., MFR 2.0) 70% by weight, hydrogenated saturated hydrocarbon resin (H2: a so-called hydrogenated petroleum resin having a cyclic portion in a copolymerization component), and a ring-ball method softening point of 1
40% by weight) and polypropylene (PP2: density 0.90 g / c) polymerized with a single-site catalyst.
m ^3, VSP135 ℃, crystalline melting point 143 ° C., MFR1.
5) A composition obtained by kneading 20% by weight.

(S3): L obtained by copolymerizing octene 1 with 5 mol% of ethylene using the single-site catalyst of the component E1.
LDPE (LL1: density 0.915 g / cm ³ , VSP
70% by weight of 91 ° C., MI 1.5, crystal melting point 95 ° C., crystallinity by DSC method: 50%) and α-olefin elastomer obtained by copolymerizing 14 mol% of propylene with α-olefin of component E2 (density: 0.88 g / cm ³ , VSP45 ℃,
MI 0.4) 15% by weight and the aforementioned PP11 of component E3
A composition in which 5% by weight is kneaded.

[0123]

EXAMPLES Examples 1 to 5 Base resin (A) and stretch opening material (D) shown in Table 1
Is kneaded in a predetermined ratio with a biaxial kneading extruder in advance and pelletized, and the arrangement of the inner layer (M layer), the auxiliary layer, and the outer layer (S layer) is S / M / S Plasticizing and kneading by two 40 mm diameter (L / D = 37) extruders so that the extruder for the S layer is a cylinder portion corresponding to the kneading portion in the middle of the screw. Of 2% by weight of diglycerin monolaurate with respect to the ratio of the resin used as an additive, and co-extrusion from two or three types of annular dies (thickness ratio: S layer / M layer / S layer =
0.5 / 1 / 0.5), and S1, S1, S2, S2, and S3 are sequentially selected as the S layers of the first, second, third, fourth, and fifth embodiments, and the tip of the die and water are uniformly discharged. The distance between the water-cooled rings was adjusted, and a stock was stably obtained under the condition of a draw ratio (DDR) of 12.

The raw material was passed between two pairs of feed nip rolls and take-off nip rolls, heated to 82 ° C. by hot air, air was introduced into the raw material, and continuously expanded using a rectifying contact guide. The draw ratio in the direction is 3.5 times,
The film is stretched so that the transverse stretching ratio becomes 3 times, then passed between another pair of feed nip rolls and the take-off nip roll and heated to 115 ° C. by hot air, and the machine direction stretching ratio becomes 2 times. Then, the film is stretched again so that the stretching ratio in the transverse direction becomes 2.0 times, and is further passed between another pair of feed nip rolls and take-off nip rolls, and is formed into a tube shape at 120 ° C. by hot air from the circumferential direction. And heat-set for 30 seconds while contracting 5% in the vertical direction and 5% in the horizontal direction.

Finally, the stretched M layer was peeled from the S layer while slitting both ends to obtain a desired fluid-permeable microporous film (24 μm in thickness). These properties are listed in Table 1. They did not generate static electricity at the time of peeling, and had good off-line high-speed peelability (100 m / min). Furthermore, even in each step, there was an appropriate adhesiveness, and there was no separation and separation.

[0126]

[Table 1]

Examples 6 to 10 The compositions of each of the base resins (A) and (B) and the stretch-openable substance (D) shown in Table 2 were previously biaxially kneaded and extruded at a predetermined ratio. And kneaded and pelletized. The inner layer (MA and MB layers) and the outer layer of the auxiliary layer (S
Layer: Adopt S1 formulation) S / MA / MB / MA
/ S are plasticized and kneaded by three extruders each having a diameter of 40 mm (L / D = 37) so as to form five layers (the extruder for the S layer is a cylinder corresponding to the kneading portion in the middle of the screw). 2w to the ratio of resin used as additive from part
t% diglycerin monolaurate and 1 wt% stearic acid amide are press-fitted and kneaded) and co-extruded from three types and five layers of annular dies (thickness ratio of each layer is S layer / MA layer / M).
B layer / MA layer / S layer = 1.0 / 0.5 / 1 / 0.5 /
1.0) and adjust the distance between the die tip and the water-cooled ring that uniformly distributes the water to obtain a draw ratio (DDR).
Under the conditions of 10, a raw material was obtained stably.

The raw material was passed between two pairs of feed nip rolls and take-off nip rolls, heated to 92 ° C. by hot air, air was directly introduced into the raw material, and continuously expanded using a rectifying contact guide. Stretching ratio in the direction of 4.5 times,
The film is stretched so that the stretching ratio in the transverse direction becomes 4 times, and it is further passed between another pair of feed nip rolls and take-off nip rolls. Similarly, it is formed into a tube and heated to 115 ° C. by hot air from the circumferential direction. Then, it was heat set for 20 seconds while contracting 4% in the vertical direction and 5% in the horizontal direction.

Lastly, the desired fluid-permeable microporous film (24 μm in thickness) was obtained by peeling off the S layer from the stretched multilayer film while slitting both ends. These properties are listed in Table 2. At the time of these peeling
Only the surface layer was peeled off smoothly without peeling between the layer and the MB layer, and there was no generation of static electricity, and the high-speed peeling off-line (200 m / min) was good. Furthermore, even in each step, there was an appropriate adhesiveness, and there was no separation and separation.

[0130]

[Table 2]

Examples 11 and 12 55% by volume of the above-mentioned A-2 as a base resin (A), and C-1 / C-A as an extractable organic liquid substance (C)
2 was mixed at a mixing ratio of 40/60 (vol%) by a 45 vol% biaxial kneading extruder to form an inner layer (M layer) and then an auxiliary layer as an outer layer (S layer). The S1 formulation was selected, and each layer arrangement was plasticized and kneaded with two extruders so that each layer had three layers of S / M / S, and was co-extruded from two types and three layers of annular dies (thickness ratio: S layer / M layer / S layer =
0.2 / 1 / 0.2) (Example 11), and in addition to the above, further kneaded 50% by volume of B-1 and 50% by volume of C-1 to obtain S / MA / MB / MA. / S to be 5 layers
Co-extrusion from a seed five-layer annular die (in order of thickness ratio: 0.2
/0.5/1.0/0.5/0.2) (Example 1)
2) The distance between the tip of the die and the water-cooled ring that uniformly spreads the water was adjusted, and rapidly cooled under the condition of a draw ratio (DDR) of 8 to phase-separate the resin components to stably obtain a raw material.

This raw material was passed between two pairs of feed nip rolls and take-off nip rolls, heated to 82 ° C. by hot air, air was directly injected into the raw material, and continuously expanded using a rectifying contact guide. The draw ratio in the direction is 3.5 times,
The film is stretched so that the stretching ratio in the transverse direction becomes three times, and
Heated to 95 ° C. by hot air between two sets of nip rolls and then another pair of feed nip rolls and a take-off nip roll, the stretching ratio in the machine direction is 2 times, and the stretching ratio in the transverse direction is 1. Re-stretch to 5 times, pass through another pair of feed nip rolls and take-off nip rolls, form a tube, heat to 100 ° C with hot air from the circumferential direction and 5% in the vertical direction Then, it was heat-set for 30 seconds while contracting 5% in the horizontal direction.

Finally, while stretching both ends, the stretched M layer was peeled off from the S layer, and the above-mentioned C was extracted in an extraction tank (solvent 1,1,1-trichloroethane) and dried to obtain the desired product. A fluid microporous film (thickness 23 μ) was obtained. These characteristics are as follows: Example 11 has a porosity of 54%, an air permeability of 300 (sec / 100 cc), and a 10% shrinkage temperature of 1.
65 ° C.

In Example 12, the porosity was 57% and the air permeability was 1
58 (sec / 100cc), 10% shrink temperature 165
° C, the above-mentioned battery safety (temperature difference) was 55 ° C, and the current interruption temperature was 133 ° C. All of them were not broken at the time of peeling, did not generate static electricity, and had good off-line high-speed peeling properties (100 m / min). Furthermore, even in each step, there was an appropriate adhesiveness, and there was no separation and separation.

Example 13 In the same manner as in Example 12, the extruder was equipped with a crosshead type small two-type two-layer annular die for hollow hollow fiber, and the S and M layer formulations were used. (Outside) side / M
The (inside) ratio was extruded in two layers of 1/20, quenched at a draw ratio of 13, and the M layer was uniformly phase-separated to obtain a raw (counter) yarn. Next, by a stretching method between nip rolls, the film was heated to 65 ° C. and stretched to 7.5 times in the machine direction in the machine direction. In the next step, the film was heated to 100 ° C., loosened 5% in the machine direction and heat set for 20 seconds. . Further, the S (surface) layer was continuously peeled off and extracted to obtain a porous tube.

The outer diameter is 2.5 mm, the inner diameter is 1.5 mm, the porosity is 47%, and the air permeability is 1300 sec / 100 cc.
% Shrinkage temperature is 178 ° C and water permeability (flux) is 100
cc / cm ² · Hr · atm, separation point with a bubble point (the pressure at the moment when air bubbles come out from the holes by being sequentially pressurized with air in water) is 2.6 kg / cm ² It was a hollow fiber.

Example 14 87% by volume of A-1 and D1 as a stretch-openable substance (D)
-1 was 5% by volume, D3-1 was 1% by volume, D5-1 was 1% by volume, and erucic acid amide was 1% by volume and B-3 was 5% by volume as other additives. Kneading with an extruder, selecting the S3 formulation as the inner layer (M layer) and the outer layer (S layer) of the auxiliary layer, and extruding two units each so that the layer arrangement becomes three layers of S / M / S. Kneading with plasticizer, 2 types 3
Layer co-extrusion through a circular die (thickness ratio: S layer / M layer / S
Layer = 2/1/2), and then adjust the distance between the die tip and the water cooling ring which uniformly comes out of water, and draw ratio (DDR) 8
Under the conditions described above, the raw material was quenched to obtain a stable material.

The raw material was passed between two pairs of feed nip rolls and take-off nip rolls, heated to 55 ° C. by hot air, air was introduced into the raw material, and continuously expanded using a rectifying contact guide. Stretching ratio in the direction of 4.5 times,
The film is stretched so that the stretching ratio in the transverse direction becomes 4 times, and then it is passed between another pair of feed nip rolls and the take-off nip roll and heated to 75 ° C. by hot air, and the stretching ratio in the machine direction is 2 times. And re-stretched so that the stretching ratio in the horizontal direction becomes 1.5 times, heat-set in a flat state between two sets of nip rolls, and finally strip the stretched M layer from the S layer while slitting both ends. Thus, an intended fluid-permeable microporous film (5 μm in thickness) was obtained.

These properties are as follows: porosity 50%, air permeability 1
00 (sec / 100cc), 10% shrink temperature 175 ° C
Met. In addition, no static electricity was generated at the time of peeling, and the high-speed peeling off-line (100 m / min) was good. Furthermore,
Even in each step, there was moderate adhesion, and there was no separation and separation.

[0140]

According to the present invention, there is provided a fluid-permeable microporous film which is heat-resistant, high-strength, high-performance, and excellent in thinning and productivity, and is useful in many applications such as battery separators and separation membranes. There is an effect that the manufacturing method is provided.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08J 9/28 CES C08J 9/28 CES 5H021 C08K 13/04 C08K 13/04 C08L 23/00 C08L 23/00 H01M 2/16 H01M 2/16 P // B29K 23:00 105: 04 B29L 7:00 9:00 31:14 31:34 F term (reference) 4D006 GA07 MA06 MA22 MA31 MA40 MB15 MB20 MC22X MC23X MC44X MC81 MC83 MC87 MC88 MC89 NA35 NA36 PC80 4F071 AA14 AF08 AF45 AG29 AH02 AH04 BA01 BB07 BC01 BC17 4F074 AA02 AA09 AA16 AA17 AA24 AA26 AA27 AA32 AA48 AA90 AC02 AC17 AC19 AC24 AC34 AC36 AD11 AD16 CA03 DA02 AK56A AK56J BA02 BA10A BA10B BA15 BA16 DJ01A EH202 EJ373 EJ502 EJ513 EJ912 GB41 GB90 JA03A JA04A JA06A JA20A JB16B JD02A JJ03 JK01 JL 02 JL04 YY00A 4J002 AB013 AE032 AE052 AF022 BA002 BB041 BB141 BB172 BC033 BG053 BL012 CP033 DA017 DA027 DA037 DE077 DE107 DE137 DE147 DE237 DJ007 DJ017 DJ037 DL007 EH146 EW046 FA083 FD0115 BB01 BB01 BB015 02BB HH06 HH07

Claims (8)

[Claims] 1. A thermoplastic resin (A) having at least one layer of a copolymer resin of an α-olefin and carbon monoxide having a crystal melting point of 140 to 250 ° C. as a main component, and having a porosity of 30 to 80. %, And the air permeability is 5 to 2000 sec / 1.
A fluid-permeable microporous film having a heat resistance of 100 cc and a 10% shrinkage temperature of 100 ° C. or higher. 2. At least one thermoplastic resin (A) layer mainly composed of a copolymer resin of α-olefin and carbon monoxide having a crystal melting point of 140 to 250 ° C., and a crystal melting point of 8
It has a porosity of 30 to 80% and an air permeability of at least two layers of at least one thermoplastic resin (B) layer having a polyolefin resin as a main component at 0 to 240 ° C.
A fluid-permeable microporous film having heat resistance of 2000 sec / 100 cc and a 10% shrinkage temperature of 100 ° C. or higher. 3. A thermoplastic resin (A) layer containing at least two layers including a surface layer, the main component of which is a copolymer resin of α-olefin and carbon monoxide having a crystal melting point of 140 to 250 ° C.,
It is composed of at least a three-layer microporous film composed of at least one layer including an inner layer of a thermoplastic resin (B) containing a polyolefin resin having a crystal melting point of 80 to 240 ° C. as a main component, and having a porosity of 30 to 80%. Yes, air permeability 5-20
A fluid-permeable microporous film having a heat resistance of 00 sec / 100 cc and a 10% shrinkage temperature of 100 ° C. or higher. 4. A thermoplastic resin (A) containing a copolymer resin of α-olefin and carbon monoxide having a crystal melting point of 140 to 250 ° C. as a main component and 15 to 90 parts by volume, which is extractable, and A microporous formation precursor layer composed of a composition having a viscosity of not more than 1000 CPS at 85 ° C. and containing 85 to 10 parts by volume of an inert organic liquid substance (C) as a main component is extruded with a die, and directly extruded with a heat transfer medium. Or indirectly quenched and solidified, and then at a temperature not lower than 15 ° C. and not higher than the temperature obtained by adding 50 ° C. to the Vicat softening point of the thermoplastic resin (A) constituting the precursor layer, and not higher than the crystal melting point of the resin. Under the temperature condition, the area stretching ratio in at least one direction is 2 times or more and 50 times or more.
A method for producing a heat-resistant, fluid-permeable, microporous film, characterized in that the microporous film is obtained by drawing the substance (C) before and after stretching the film to twice or less. 5. A thermoplastic resin (A) comprising a copolymer resin of α-olefin and carbon monoxide having a crystal melting point of 140 to 250 ° C. as a main component, and a polyolefin resin having a crystal melting point of 80 to 240 ° C. -Based thermoplastic resin (B)
15 to 90 parts by volume, at least one of a composition which is extractable, has a viscosity at 200 ° C. of 1000 CPS or less, and has 85 to 10 parts by volume of an inert organic liquid substance (C) as a main component. The microporous forming precursor layer of the layer is extruded by a multilayer die, solidified by direct or indirect quenching with a heat transfer medium, and then Vicat softening of the thermoplastic resin (A) at 15 ° C. or higher and constituting the precursor layer. At a temperature not higher than the temperature obtained by adding 50 ° C. to the point and at a temperature not higher than the crystal melting point of the resin, the film is stretched in at least one direction by an area stretch ratio of 2 times or more and 50 times or less. A method for producing a heat-resistant, fluid-permeable microporous film having at least two layers, which is obtained by extracting C). 6. A thermoplastic resin (A) having a crystal melting point of 140 to 250 ° C. and containing a copolymer resin of α-olefin and carbon monoxide as a main component, in an amount of 99 to 50 parts by volume, and D1 to D4 described below.
At least one kind of stretch opening material (D) 1 selected from
D1: A thermoplastic resin having a solubility parameter difference of not more than 3 with respect to the resin (A) as a base material and having an elastic modulus of 120% or more of the resin (A) is 1 ５０50 parts by volume, D2: The difference in solubility parameter with the resin (A) as the base material is within 3, the elastic modulus is less than 120% of the resin (A), and the crystallinity is 40% or more. The thermoplastic resin (A) is different from the thermoplastic resin (A) in an amount of 1 to 50 parts by volume. D3: The difference in solubility parameter with the resin (A) as the base material is 3 or more, and the liquid is at least liquid at the extrusion processing temperature. D4: a difference in solubility parameter between the resin (A) as a substrate and the resin (A) is 3 or less, and an organic compound which is at least liquid at an extrusion processing temperature is 1 to 20 parts by volume. Part, D5: an organic or organic compound having an average particle diameter of 10 μm or less 1 to 10 parts by volume of at least one filler selected from inorganic-based, a microporous forming precursor layer consisting of extruded by a die, quenched and solidified directly or indirectly by a heat transfer medium, and then at 15 ° C or higher. And at a temperature not higher than the temperature obtained by adding 50 ° C. to the Vicat softening point of the thermoplastic resin (A) constituting the precursor layer, and at a temperature not higher than the crystal melting point of the resin, in an area stretch ratio in at least one direction, A method for producing a heat-resistant, fluid-permeable, microporous film, characterized in that a microporous film is obtained by stretching the precursor layer by a factor of 2 to 50 and forming microporosity in the precursor layer. 7. A thermoplastic resin (A) mainly composed of a copolymer resin of α-olefin and carbon monoxide having a crystal melting point of 140 to 250 ° C. and a polyolefin resin having a crystal melting point of 80 to 240 ° C. Thermoplastic resin (B) 9 as a main component
9 to 50 parts by volume of the stretch-openable substance (D) according to claim 6.
At least one microporous forming precursor layer comprising a composition comprising 1 to 50 parts by volume is extruded by a multilayer die, quenched and solidified directly or indirectly by a heat transfer medium,
At least 5 ° C. and not more than the temperature obtained by adding 50 ° C. to the Vicat softening point of the thermoplastic resin (A) constituting the precursor layer, and not more than the crystal melting point of the resin, the area is at least one direction. A method for producing a heat-resistant, fluid-permeable, microporous film, characterized in that a microporous film is obtained by stretching the film at a stretching ratio of 2 to 50 times to form a microporous film in the precursor layer. 8. A thermoplastic resin (A) mainly comprising a copolymer resin of an α-olefin and carbon monoxide having a crystal melting point of 140 to 250 ° C. and / or a polyolefin resin having a crystal melting point of 80 to 240 ° C. -Based thermoplastic resin (B)
A microporous formation precursor layer, and at least one further layer,
An auxiliary layer (S) made of a non-fluid resin composition containing a thermoplastic resin different from the resin constituting the precursor layer as a main component,
At the same time, co-extruded with a multilayer die, quenched and solidified directly or indirectly with a heat transfer medium, and then at a temperature of 15 ° C. or higher and 50 ° C. added to the Vicat softening point of the thermoplastic resin (A) constituting the precursor layer. The microporous film is stretched in at least one direction at a temperature of not more than the crystal melting point of the resin to at least one direction at an area stretch ratio of 2 to 50 times, and then the auxiliary layer is peeled off. A method for producing a heat-resistant, fluid-permeable, microporous film, characterized in that: