JP6617426B2 - Gas permeable film - Google Patents

Description

  The present invention relates to a gas permeable film, and more particularly to a gas permeable film used for various industrial applications.

  Conventionally, a gas separation method using a gas separation film is known to be used for separation of various gases because it is more energy efficient than other gas separation methods and the structure of the apparatus is simple. As such a gas separation film, what is provided with the porous support membrane and the thin film of gas separation resin provided in the surface is known. With such a layer configuration, gas permeability can be secured while securing strength by the porous support membrane.

  For example, a film in which a fluorine-based gas-separable thin film is provided on a porous support membrane made of polyolefin has been proposed (for example, see Patent Document 1 below).

WO2007 / 125944 pamphlet

  However, the film described in Patent Document 1 has low adhesion between the porous support membrane and the fluorine-based gas separation thin film. Therefore, it is difficult to provide a fluorine-based gas-separable thin film on the porous support membrane, and even when a fluorine-based gas-separable thin film can be provided on the porous support membrane, interfacial peeling is likely to occur between them, As a result, there is a problem that durability is lowered.

  Then, this invention makes it a subject to provide the gas-permeable film which is excellent in durability, while being excellent in gas permeability.

  As a result of intensive studies in view of the above problems, the inventors of the present invention include a porous layer made of a polyolefin resin and a nonporous layer having a specific thickness mainly composed of a specific polymethylpentene resin. It has been found that the above problems can be solved by a gas permeable film, and the present invention has been completed.

That is, according to the first invention of the present invention, a porous layer made of a polypropylene resin containing a β crystal nucleating agent,
A polymethylpentene resin having a heat of fusion of 0.1 to 35 mJ / mg as a main component is provided on one surface in the thickness direction of the porous layer, and the thickness ratio of the nonporous layer in the film is 0.0001 or more, 0. a nonporous layer having less than 3 thickness, and wherein the Rukoto such being stretched, the gas permeable film is provided.

  According to a second aspect of the present invention, there is provided a permeable film according to the first aspect, wherein the nonporous layer has a thickness of 5 nm to 1 μm.

Furthermore, according to the third invention of the present invention, in the first or second invention, the oxygen permeability is 20 × 10 ⁵ cm ³ / m ² · 24 hr · atm or more. A functional film is provided.

  According to a fourth aspect of the present invention, there is provided a gas permeable film according to any one of the first to third aspects, wherein the porous layer is a porous film.

According to the fifth aspect of the present invention , a polymethylpentene resin having a porous layer made of a polyolefin resin and a heat quantity of fusion of 0.1 to 35 mJ / mg provided on one surface in the thickness direction of the porous layer. In a gas permeable film comprising a non-porous layer having a thickness ratio of 0.0001 or more and less than 0.3 to a non-porous layer relative to the film Gas permeation characterized in that it is produced by applying a solution in which a resin composition having a heat quantity of 0.1 to 35 mJ / mg is dissolved to one side in the thickness direction of the porous layer, drying and then stretching. A method for producing a conductive film is provided.

According to the sixth aspect of the present invention, a polymethylpentene resin having a porous layer made of polypropylene resin and a heat quantity of fusion of 0.1 to 35 mJ / mg provided on one surface in the thickness direction of the porous layer. In a method for producing a gas permeable film comprising a non-porous layer having a thickness ratio of 0.0001 or more and less than 0.3 in a non-porous layer in a film. Gas permeation characterized in that it is produced by applying a solution in which a resin composition having a heat quantity of 0.1 to 35 mJ / mg is dissolved to one side in the thickness direction of the porous layer, drying and then stretching. A method for producing a conductive film is provided.

  Since the gas-permeable film of the present invention includes a porous layer and a non-porous layer having a specific range of thickness, which is made of a polymethylpentene resin, the gas-permeable film is excellent in gas permeability.

  Furthermore, since the polyolefin resin in the porous layer and the polymethylpentene resin in the nonporous layer are both polyolefin, the adhesion between the porous layer and the nonporous layer is high, and there is no adhesion on one surface in the thickness direction of the porous layer. Interfacial peeling between the porous layer and the nonporous layer can be suppressed while the porous layer is reliably provided. Therefore, the gas permeable film of the present invention is excellent in durability.

FIG. 1 shows a cross-sectional view of one embodiment of the gas permeable film of the present invention. FIG. 2 shows an enlarged cross-sectional view of the gas permeable film shown in FIG.

  With reference to FIG. 1, one embodiment of the gas permeable film of this invention is described.

1. Gas-permeable film As shown in FIG. 1, the gas-permeable film 1 includes a porous layer 2 and a non-porous layer 3 provided on the surface (one surface in the thickness direction) of the porous layer 2. Hereinafter, each of the porous layer 2 and the non-porous layer 3 will be sequentially described.

2. Porous layer The porous layer 2 has a role of a substrate or a support layer in the gas permeable film 1. Although not shown, the porous layer 2 has a large number of fine holes communicating in the thickness direction. Such a large number of pores (porous) are continuous in the thickness direction independently of each other. The shape (in plan view) of the porous layer 2 when viewed in the thickness direction is not particularly limited. Examples of the porous layer 2 include a porous film, a hollow fiber membrane, and a nonwoven fabric, and a porous film is preferable.

  The porous layer 2 is made of a polyolefin resin.

  Examples of the polyolefin resin include polymerization of α-olefin such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene. Examples thereof include homopolymers and copolymers obtained. The polyolefin resin can contain two or more of these homopolymers or copolymers. The polyolefin resin is preferably an α-olefin component polymer (polypropylene resin) containing propylene as an essential component, preferably an α-olefin component polymer (polyethylene resin) containing ethylene as an essential component. Is mentioned. As the polyolefin resin, from the viewpoint of maintaining the mechanical strength and / or heat resistance of the gas permeable film 1 and being excellent in waterproofness and adhesion to the non-porous layer 3, a polypropylene resin is more preferable.

  Examples of the polypropylene resin include a propylene homopolymer (homopropylene) obtained by homopolymerizing propylene, for example, propylene, ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene. , 1-octene, 1-nonene, 1-decene and other α-olefins (α-olefins other than propylene) such as random copolymers or block copolymers obtained by random copolymerization or block copolymerization. A polymer etc. are mentioned.

  The polypropylene resin preferably includes a propylene homopolymer.

  The propylene homopolymer has, for example, an isotactic structure, a syndiotactic structure, or an atactic structure. The propylene homopolymer preferably has an isotactic structure.

The isotactic pentad fraction (mmmm fraction) of the propylene homopolymer indicates the stereoregularity of the propylene homopolymer, and is, for example, 80% or more, preferably 83% or less, more preferably For example, it is 99% or less, preferably 98% or less, more preferably 97% or less. When the isotactic pentad fraction of the propylene homopolymer is not less than the above lower limit, the mechanical strength of the porous layer 2 can be prevented from being lowered. On the other hand, the upper limit of the isotactic pentad fraction of the propylene homopolymer is described as the upper limit that can be obtained industrially at the present time, but in the future, the propylene homopolymer having higher stereoregularity at the industrial level will be described. This is not the case when coalescence is developed. The isotactic pentad fraction (mmmm fraction) is such that the five methyl groups that are side chains with respect to the main chain by the carbon-carbon bond composed of any five consecutive propylene units are in the same direction. It means the proportion of meso (m) located. The isotactic pentad fraction (mmmm fraction) is calculated by ¹³ C-NMR. Specifically, the ratio of the methyl group assigned as meso (m) to the methyl group in the entire propylene homopolymer is calculated from the corresponding signal of ¹³ C-NMR. Signal assignment and quantification are described in A. It conforms to the method described in Zambelli et al (Macromolecules 8, 687, (1975)).

  The Mw / Mn of the polyolefin resin is, for example, 2.0 or more, and is, for example, 10.0 or less, preferably 8.0 or less, more preferably 6.0 or less. Mw / Mn is the ratio of the weight average molecular weight (Mw) of the polyolefin resin to the number average molecular weight (Mn) of the polyolefin resin, and the smaller the Mw / Mn, the narrower the molecular weight distribution. If Mw / Mn is equal to or more than the above lower limit, it is possible to prevent a decrease in extrudability and prevent a decrease in industrial productivity. On the other hand, if Mw / Mn is less than or equal to the above upper limit, it is possible to prevent the low molecular weight component from being excessively increased and to prevent the mechanical strength of the porous layer 2 from being lowered. Mw / Mn of the polyolefin resin is measured by a GPC (gel permeation chromatography) method.

  The melt flow rate (MFR) of the polyolefin resin is not particularly limited, but is usually 0.5 g / 10 min or more, preferably 1.0 g / 10 min or more, for example, 15 g / 10 minutes or less, preferably 10 g / 10 minutes or less. When the MFR of the polyolefin resin is not less than the above lower limit, the resin has a high melt viscosity at the time of molding processing, and sufficient productivity can be ensured. On the other hand, if the MFR of the polyolefin resin is not more than the above upper limit, the mechanical strength of the porous layer 2 can be sufficiently maintained. The MFR of the polyolefin resin is measured according to JIS K7210 (1999). For example, when the polyolefin resin is a polypropylene resin, the MFR is measured under the conditions of a temperature of 230 ° C. and a load of 2.16 kg.

The density of the polyolefin resin is, for example, 0.850 g / cm ³ or more, preferably 0.00.
And at 870 g / cm ³ or more, and is, for example, 0.970 g / cm ³ or less, preferably,
0.950 g / cm ³ or less.

  The polyolefin resin is a known polymerization method using a known olefin polymerization catalyst, for example, slurry polymerization using a multisite catalyst typified by a Ziegler-Natta type catalyst or a single site catalyst typified by a metallocene catalyst, It can be obtained by a melt polymerization method, a bulk polymerization method, a gas phase polymerization method, or a bulk polymerization method using a radical initiator.

  Commercially available polyolefin resin can be used. Specifically, for example, when it is a polypropylene resin, “NOVATEC PP”, “WINTEC” (manufactured by Nippon Polypro Co., Ltd.), “NOTIO”, “Toughmer” "XR" (Mitsui Chemicals, Inc.), "Zeras", "Thermorun" (Mitsubishi Chemical, Inc.), "Sumitomo Noblen", "Tough Selenium" (above, Sumitomo Chemical), "Prime Polypro", " “Prime TPO” (manufactured by Prime Polymer Co., Ltd.), “Adflex”, “Adsyl”, “HMS-PP (PF814)” (manufactured by Sun Allomer Co., Ltd.), “Versify”, “Inspire” (manufactured by Dow Chemical Co., Ltd.) ) Etc. are used.

  In addition, an additive can be added to the polyolefin resin at an appropriate ratio as long as the effects of the present invention are not impaired. Additives include, for example, various resins for promoting the formation of pores and imparting moldability, low molecular weight compounds such as wax, recycled resins generated from trimming loss such as ears, silica, talc, Inorganic particles such as kaolin and calcium carbonate, pigments such as carbon black, flame retardants, weather resistance stabilizers, heat stabilizers, antistatic agents, melt viscosity modifiers, crosslinking agents, lubricants, nucleating agents, plasticizers, Examples thereof include an anti-aging agent, an antioxidant, a light stabilizer, an ultraviolet absorber, a neutralizing agent, an antifogging agent, an antiblocking agent, a slip agent, and a coloring agent. The additive can be added at the time of polymerization of the α-olefin component, at the time of molding the preform described below, and at least at the time of porosity.

  The polyolefin resin is prepared as a preform such as pellets.

  Further, when the polyolefin resin is a polypropylene-based resin, as will be described later, a treatment for promoting the generation of β crystals for forming a porous film from a nonporous film can be performed. Specifically, for example, a method in which a substance that promotes the formation of α crystals of polypropylene resin is not added, or a method of irradiating polypropylene resin with γ rays as described in Japanese Patent No. 3739481, polypropylene And a method of adding a β crystal nucleating agent to the resin. Preferably, a method of adding a β crystal nucleating agent to a polypropylene resin is used.

The β crystal nucleating agent is not particularly limited as long as it increases the generation and growth of β crystals of the polypropylene resin. Examples of the β crystal nucleating agent include amide compounds, tetraoxaspiro compounds, quinacridones, iron oxide having a nanoscale size, potassium 1,2-hydroxystearate, magnesium benzoate or magnesium succinate, magnesium phthalate, etc. Alkali or alkaline earth metal salts of carboxylic acids, aromatic sulfonic acid compounds typified by sodium benzenesulfonate or sodium naphthalenesulfonate, di- or triesters of dibasic or tribasic carboxylic acids, phthalocyanine blue Phthalocyanine pigments typified by, for example, component A which is an organic dibasic acid, and component B which is an oxide, hydroxide or salt of a Group 2 metal of the periodic table, a cyclic phosphorus compound And magnesium compound Things and the like. In addition, specific examples of the β crystal nucleating agent include compounds described in JP2003-306585A, JP08-144122A, and JP09-194650A.
One type of β crystal nucleating agent may be used alone, or two or more types may be used in combination.

In addition, a commercial product of a polypropylene resin to which a β crystal nucleating agent is added in advance can be used,
Specific examples include polypropylene manufactured by Aristech “Bepol B-022SP”, polypropylene manufactured by Borealis “Beta (β) -PP BE60-7032,” polypropylene manufactured by Mayzo “BNX BETAPP-LN”, and the like.

  The proportion of the β crystal nucleating agent is appropriately adjusted depending on the type of the β crystal nucleating agent or the composition of the polypropylene resin, and is, for example, 0.0001 parts by mass or more, preferably 0.001 with respect to 100 parts by mass of the polypropylene resin. More than mass part, More preferably, it is 0.01 mass part or more, for example, 5 mass parts or less, Preferably, it is 3 mass parts or less, More preferably, it is 1 mass part or less. If the ratio of the β crystal nucleating agent is equal to or more than the above lower limit, the β crystal of the polypropylene resin can be sufficiently generated and grown at the time of producing the nonporous film, and desired gas permeability can be obtained. On the other hand, if the ratio of the β crystal nucleating agent is not more than the above upper limit, it becomes economically advantageous, and the bleeding of the β crystal nucleating agent on the surface of the porous layer 2 can be suppressed.

  Next, the porous layer 2 is formed from the polyolefin resin.

In order to form the porous layer 2 from a polyolefin resin, from the above-described polyolefin resin,
As shown in FIG. 2, the porous layer 2 is formed so as to have fine holes 5.

  Specifically, when the porous layer 2 is a porous film, for example, first, a non-porous film made of a polyolefin resin (the definition of “non-porous” will be described in detail later) is prepared. Next, the nonporous film is made porous.

  In order to produce a non-porous film, for example, a preformed polyolefin resin is melted using an extruder, then extruded from a die such as a T die, and cooled and solidified by a casting roll. The temperature of a casting roll is 100 degreeC or more, for example, Preferably, it is 120 degreeC or more, for example, is 140 degrees C or less, Preferably, it is 130 degrees C or less.

  Alternatively, a tube can be formed from a polyolefin resin pellet by a tubular method (inflation extrusion method), and the tube can be cut open to obtain a film. In order to produce a non-porous film, it is preferable to extrude a polyolefin resin preform while melting using an extruder, and then to cool and solidify.

  Thereafter, the nonporous film is made porous. In order to make the nonporous film porous, for example, if a β crystal based on a β crystal nucleating agent is generated in the nonporous film, the nonporous film is stretched. In order to stretch the non-porous film, for example, a known method such as stretching or uniaxial stretching by wet or dry method is used. The stretching method includes, for example, a roll stretching method, a rolling method, a tenter stretching method, a simultaneous biaxial stretching method, a sequential biaxial stretching, and the like. can do. Preferably, biaxial stretching is mentioned from a viewpoint of controlling a porous structure.

  First, from the viewpoint of controlling the porous structure before coating the nonporous layer, it is preferable to uniaxially stretch the nonporous film. In the uniaxial stretching, the temperature is, for example, 80 ° C. or more, preferably 90 ° C. or more, and for example, 120 ° C. or less, preferably 110 ° C. or less. The non-porous film is stretched by at least twice, preferably at least 3 times, for example, at most 10 times, preferably at most 5 times.

  After the above-described uniaxial stretching, it is preferable that the second axis is stretched in a direction perpendicular to the uniaxial stretching direction (hereinafter referred to as a transverse direction) through application of a non-porous layer described later.

  By stretching as described above, as shown in FIG. 2, pores are formed in the non-porous film, whereby the porous layer 2 is produced.

In addition, when the polyolefin resin contains a plasticizer as an additive, if necessary,
The plasticizer in the non-porous film before stretching or the porous film after stretching described above can be extracted with a solvent and dried.

The porous layer 2 is formed from a single layer, or is manufactured by stacking a plurality of layers. The porous layer 2 is
As a whole, it may be made of a polyolefin resin. For example, a plurality of different types of porous layers 2 of polyolefin resin may be stacked.

  When a plurality of different types of porous layers 2 are stacked, for example, the porous layer 2 is manufactured by the following method. That is, for example, (1) a method of laminating each of a plurality of non-porous films and then laminating or bonding each of the plurality of porous films with an adhesive, for example, (2) a plurality of non-porous films A method for producing a laminated non-porous film by superimposing each of the porous films, and then making the laminated non-porous film porous, for example, (3) after making any one layer of a plurality of non-porous films porous, porous A method of stacking a film and the remaining non-porous film, for example, (4) A method of forming a porous porous film 3 by forming a porous layer 3 and then applying a coating such as inorganic / organic particles or depositing metal particles. Etc. are used. Preferably, from the viewpoint of simplicity of process and productivity, the method (2) is used. More preferably, in order to ensure interlayer adhesion of a plurality of nonporous films, a laminated nonporous film is formed by coextrusion. The method of making it porous after producing is mentioned.

  The porous layer 2 can be subjected to a surface treatment. For example, for the purpose of improving dimensional stability, heat treatment or relaxation treatment is performed after stretching. Further, the surface of the porous layer 2 is subjected to a surface treatment such as corona discharge or plasma treatment so as not to deteriorate the porous layer 2, thereby ensuring strong interlayer adhesion between the porous layer 2 and the nonporous layer 3. Can do. However, when the non-porous layer 3 is formed by a coating and drying method (described later), strong interlayer adhesion between the porous layer 2 and the non-porous layer 3 is ensured, so that the above-described surface treatment is not performed. May be.

The thickness of the porous layer 2 is, for example, 1 μm or more, preferably 5 μm or more, more preferably
10 μm or more, and for example, 1000 μm or less, preferably 100 μm or less,
More preferably, it is 50 μm or less. If the thickness of the porous layer 2 is less than or equal to the above upper limit, good gas permeability can be ensured by stretching after application of the non-porous layer described below. If the thickness of the porous layer 2 is not less than the above lower limit, the nonporous layer 3 can be reliably supported and the mechanical strength of the gas permeable film 1 can be improved.

The average pore diameter of the pores in the porous layer 2 is, for example, 0.01 μm or more, preferably 0.05 μm or more, more preferably 0.1 μm or more, and, for example, 10 μm or less, preferably 5 μm or less. Preferably, it is 1 μm or less. If the average hole diameter of the holes is not more than the above upper limit, the nonporous layer 3 can be reliably supported and the mechanical strength of the gas permeable film 1 can be improved. If the average hole diameter of the holes is equal to or greater than the above lower limit, good gas permeability can be secured. The average hole diameter of the holes is measured in accordance with, for example, ASTM F316-86.

  The air permeability of the porous layer 2 is, for example, 100 seconds / 100 mL or more, preferably 1000 seconds / 100 mL or more, more preferably 10,000 seconds / 100 mL or more, and, for example, 50000 seconds / 100 mL or less. If the air permeability of the porous layer 2 is equal to or higher than the above lower limit, sufficient oxygen permeability is imparted by stretching after applying the nonporous layer described later in addition to supporting the nonporous layer as the base material of the gas permeable film 1. It is possible. The air permeability of the porous layer 2 is measured as a Gurley value by the method described in Examples below.

3. Non-porous layer The non-porous layer 3 has a role of a water-resistant layer that imparts good water resistance, gas permeability, gas separation property and the like to the gas-permeable film 1. As shown in FIG. 1, the nonporous layer 3 is provided on the entire surface (upper surface) of the porous layer 2. The nonporous layer 3 is formed as a solid dense layer. Further, “non-porous” in the non-porous layer 3 means a state in which the non-porous layer is not intentionally opened, that is, the non-porous layer due to an unintended factor in the process of manufacturing the non-porous layer 3 and the gas permeable film 1. It is also assumed that a state in which fine holes (regardless of the presence or absence of communication) are generated in 3 is also “non-hole”. When the nonporous layer 3 is formed by a coating and drying method to be described later, as shown in FIG. 2, the nonporous layer 3 has an infiltrating portion 4 that infiltrates from the back surface of the nonporous layer 3 toward the inside of the porous layer 2. You may do it.

The nonporous layer 3 is mainly composed of a polymethylpentene resin.
Here, the main component means that it usually exceeds 50% by weight, preferably 70% by weight or more, more preferably 90% by weight or more.

  The polymethylpentene resin is a polymer obtained by polymerizing a monomer component containing methylpentene as a main component (for example, 50 wt% or more).

Examples of methylpentene include 1-pentene, specifically, 4-methyl-1-pentene (or 4-methylpentene-1).

  Examples of the polymethylpentene resin include homopolymers obtained by polymerizing methylpentene, for example, methylpentene and other polymers such as ethylene, propylene, 1-butene, isobutene, and 1-hexene. Examples thereof include copolymers obtained by copolymerizing with α-olefins (specifically, α-olefins having 2 or more carbon atoms excluding methylpentene). Other α-olefins can be used alone or in combination of two or more.

  The polymethylpentene resin is preferably a copolymer, and more preferably obtained by random copolymerization or block copolymerization of methylpentene and a linear α-olefin having 2 or more carbon atoms. And a random copolymer or a block copolymer.

  The weight ratio of methylpentene in the copolymer (that is, the weight ratio of methylpentene in the monomer component for constituting the copolymer) is, for example, 50 wt% or more, preferably 60 wt% or more, more preferably 70 wt%. For example, it is 99 wt% or less, preferably 90 wt% or less, and more preferably 80 wt% or less. If the weight ratio of methylpentene is not less than the above lower limit, excellent gas permeability can be imparted to the gas permeable film 1. On the other hand, the weight ratio of the other α-olefin in the copolymer is, for example, 1 wt% or more, preferably 10 wt% or more, more preferably 20 wt% or more, and for example, 50 wt% or less, It is 40 wt% or less, more preferably 30 wt% or less.

The heat of fusion of the polymethylpentene resin is 35 mJ / mg or less, preferably 25 mJ / mg or less, more preferably 20 mJ / mg or less, and particularly preferably 15 mJ / mg or less. 1 mJ / mg or more, preferably 1.0 mJ / mg or more, more preferably 2.0 mJ / mg or more. If the weight ratio of methylpentene is not less than the above lower limit, excellent gas permeability can be imparted to the gas permeable film 1.
Here, the amount of heat of fusion was raised from −40 ° C. to 250 ° C. at a heating rate of 10 ° C./min with 10 mg of polymethylpentene resin according to JIS-K7121, using a Diamond DSC manufactured by PerkinElmer Japan. DSC when held at 250 ° C for 1 minute, cooled to -40 ° C at a cooling rate of 10 ° C / minute, held at -40 ° C for 1 minute, and then heated again to 250 ° C at a heating rate of 10 ° C / minute It can be obtained from a curve.

The weight average molecular weight of the polymethylpentene resin is, for example, 0.5 × 10 ⁵ or more, preferably 1 × 10 ⁵ or more, and for example, 10 × 10 ⁵ or less, preferably 8 × 10 ⁵ or less. It is. If the weight average molecular weight of the polymethylpentene resin is not more than the above upper limit, the nonporous layer 3 can be formed on the surface of the porous layer 2 with good productivity, and if it is not less than the above lower limit, the strength of the nonporous layer 3 can be increased. Can be maintained. The weight average molecular weight of the polymethylpentene resin is measured by the GPC method.

  A commercially available product can be used as the polymethylpentene resin, and specifically, the TPX series (manufactured by Mitsui Chemicals) is used.

  It should be noted that the above-mentioned additives can be added to the polymethylpentene resin at an appropriate ratio as long as the effects of the present invention are not impaired. The additive can be added when the polymethylpentene resin is produced or when the polymethylpentene resin described later is dissolved.

  In order to provide the nonporous layer 3 on the surface of the porous layer 2, for example, a method of directly forming the nonporous layer 3 on the surface of the porous layer 2 prepared in advance, or the porous layer 2 and the nonporous layer 3 are individually manufactured. Then, a method in which the nonporous layer 3 is bonded to the surface of the porous layer 2, a method in which the porous layer 2 and the nonporous layer 3 are laminated by coextrusion, and the like are used. Among them, there is a large difference in the moldable temperature with the polymethylpentene resin depending on the viewpoint of accurately forming the nonporous layer 3 with a desired thickness described later, and depending on the type of the polyolefin resin of the porous layer 2, From the viewpoint that it is difficult to simultaneously mold the porous layer 2 and the nonporous layer 3 by coextrusion, and further from the viewpoint of improving productivity, preferably, the nonporous layer 3 is directly formed on the surface of the porous layer 2 prepared in advance. The method of forming is mentioned.

  In order to directly form the nonporous layer 3 on the surface of the porous layer 2, for example, a polymethylpentene resin is dissolved in a solvent to prepare a solution (coating solution), and the prepared coating solution is applied to the surface of the nonporous layer 3. And dried to remove the solvent (coating drying method).

  The solvent contains at least one good solvent for the polymethylpentene resin. That is, the solvent may be composed of only one or two or more good solvents, and may further contain one or more poor solvents for the polymethylpentene resin. A mixed solvent composed of a good solvent and a poor solvent can improve the handleability of a liquid composition composed of a polymethylpentene resin and a mixed solvent while ensuring solubility in the polymethylpentene resin. The good solvent means a solvent having high solubility in polymethylpentene resin, the poor solvent means a solvent having low solubility in polymethylpentene resin, and these are the types of polymethylpentene resin. It is appropriately selected depending on.

  Examples of the good solvent include hydrocarbon solvents that may contain a halogen atom. Examples of the hydrocarbon solvent include alicyclic hydrocarbon solvents. As the alicyclic hydrocarbon solvent, for example, C3-6 cycloalkane optionally having an alkyl group such as methylcyclobutane, cyclopentane, methylcyclopentane, and cyclohexane, such as cyclopentene and methylcyclopentene, Examples thereof include C4-5 cycloalkene which may have an alkyl group. Preferably, C3-6 cycloalkane which may have an alkyl group is mentioned. The good solvents can be used alone or in combination of two or more.

Examples of the poor solvent include propylene oxide, cyclohexene oxide, furan,
3- to 7-membered cyclic ether having one ether bond such as 2-methylfuran, tetrahydrofuran (THF), tetrahydrofurfuryl alcohol, pyran, dihydropyran, tetrahydropyran, etc., preferably 5 having one ether bond A 6-membered cyclic ether, more preferably, THF and tetrahydropyran are mentioned. The poor solvent can be used alone or in combination of two or more.

  The boiling point of the solvent is, for example, 50 ° C. or higher, preferably 55 ° C. or higher, more preferably 60 ° C. or higher, still more preferably 65 ° C. or higher, and for example, 200 ° C. or lower, preferably 150 ° C. or lower. More preferably, it is 130 ° C. or lower, and further preferably 120 ° C. or lower. If the boiling point of the solvent is equal to or higher than the above lower limit, the volatility can be prevented from being excessively increased, and the handling property of the coating liquid can be prevented from being lowered. Can be easily dried.

  When preparing a coating liquid by dissolving a polymethylpentene resin in a solvent, the concentration of the polymethylpentene resin in the coating liquid (that is, the ratio of the polymethylpentene resin and the polymethylpentene resin to the solvent) is, for example, 0.01 mass% or more, and for example, 50 mass% or less, preferably 10 mass% or less. If the concentration of the polymethylpentene resin in the coating liquid is not less than the above lower limit, the nonporous layer 3 can be reliably formed by applying the coating liquid to the surface of the porous layer 2 and drying it. On the other hand, if the concentration of the polymethylpentene resin in the coating liquid is not more than the above upper limit, the nonporous layer 3 is formed without hindering gas permeability and oxygen / nitrogen separation, and the thickness of the nonporous layer 3 is reduced. A desired range can be set.

  In order to dissolve the polymethylpentene resin in the solvent, the polymethylpentene resin and the solvent are blended, and they are, for example, 20 minutes or more, preferably 1 hour or more, for example, 5 hours or less, preferably Stir for 3 hours or less.

  Application of the coating liquid to the surface of the porous layer 2 is not particularly limited as long as a method that can cope with the required thickness and application area of the porous layer 2 is used. In order to apply the coating solution to the surface of the porous layer 2, for example, a gravure coater method (including a small diameter gravure coater method), a reverse roll coater method, a transfer roll coater method, a kiss coater method, a dip coater method, a knife coater method, air Examples include a doctor coater method, a blade coater method, a rod coater method, a bar coater method, a squeeze coater method, a cast coater method, a die coater method, a screen printing method, and a spray coating method.

  Thereafter, the coating liquid is dried to remove the solvent. The drying time is, for example, 1 minute or more, preferably 10 minutes or more, and for example, 50 minutes or less, preferably 30 minutes or less.

  According to the coating and drying method, the infiltrated portion 4 is formed in the nonporous layer 3. By the infiltrating portion 4, an anchor effect (described later) of the nonporous layer 3 with respect to the porous layer 2 can be exhibited.

  In addition to making the porous layer 2 and the non-porous layer 3 thinner, it is preferred to perform the second axial stretching in a direction perpendicular to the uniaxial stretching direction described above in order to improve the air permeability of the porous layer 2. As the stretching method, for example, the stretching method described above can be applied.

The stretching temperature is, for example, 130 ° C. or higher, preferably 140 ° C. or higher.
Using a horizontal stretcher that is 170 ° C. or lower, preferably 160 ° C. or lower, in the horizontal direction, for example,
The laminated film of the porous layer 2 and the nonporous layer 3 is stretched 1.5 times or more, preferably 2 times or more, for example, 5 times or less, preferably 3 times or less.

  The thickness of the non-porous layer 3 is 5 nm or more, preferably 50 nm or more, and less than 4 μm, preferably 2 μm or less, more preferably 1 μm or less, and further preferably 0.3 μm or less. The thickness of the non-porous layer 3 is measured by the method described in Examples described later.

  If the thickness of the nonporous layer 3 is less than the lower limit, it is difficult to produce the nonporous layer 3 as a uniform layer. On the other hand, if the thickness of the nonporous layer 3 is not less than the above lower limit, the nonporous layer 3 can be produced as a uniform layer.

  Moreover, if the thickness of the nonporous layer 3 is not less than the above upper limit (or exceeds the above upper limit), the gas permeable film 1 cannot be provided with good gas permeability. On the other hand, if the thickness of the nonporous layer 3 is less than the above upper limit (or less than the above upper limit), good gas permeability can be imparted to the gas permeable film 1.

  The thickness of the non-porous layer 3 is measured by the method described in Examples described later.

  The thickness ratio of the porous layer 2 to the film 1 (= thickness of the non-porous layer 3 / thickness of the expected permeable film 1) is, for example, less than 0.3, preferably 0.15 or less, more preferably 0. .05 or less, more preferably 0.01 or less, and for example, 0.0001 or more.

4). Physical properties of gas permeable films
The thickness of the gas permeable film 1 is, for example, 2 μm or more, preferably 10 μm or more, and, for example, 1000 μm or less, preferably 100 μm or less. The thickness of the gas permeable film 1 is measured by the method described in Examples described later.

The interfacial peel strength between the porous layer 2 and the nonporous layer 3 in the gas permeable film 1 is, for example, 2N
/ 18mm or more, preferably 3N / 18mm or more, more preferably 4N / 18mm or more, still more preferably 5N / 18mm or more, and for example, 100N / 18mm or less. If the interfacial peel strength between the nonporous layer 3 and the porous layer 2 is not less than the above lower limit, the excellent adhesion between the nonporous layer 3 and the porous layer 2 is ensured, and the interface between the nonporous layer 3 and the porous layer 2 is secured. Peeling can be suppressed. The interfacial peel strength is measured by the method described in Examples described later.

The water pressure resistance of the gas permeable film 1 is, for example, 1 kgf / cm 2 or more, preferably 5 k.
gf / cm 2 or more, and for example, 100 kgf / cm 2 or less. When the water pressure resistance of the gas permeable film 1 is equal to or higher than the lower limit, the excellent water resistance of the gas permeable film 1 can be ensured. In order to set the water pressure resistance of the gas permeable film 1 to the above lower limit or more, as will be described later, the air permeability and thickness of the porous layer 2 and the thickness of the nonporous layer 3 are appropriately adjusted. The water pressure resistance of the gas permeable film 1 is measured by the method described in Examples described later.

The oxygen permeability of the gas permeable film 1 is, for example, 20 × 10 ⁵ cm ³ / m ² · 24 hr · atm or more, preferably 50 × 10 ⁵ cm ³ / m ² · 24 hr · atm or more, more preferably 100 × 10 ⁵ cm ³ / m ² · 24 hr · atm or more, more preferably 210 × 10 ⁵ cm ³ / m ² · 24 hr · atm or more, for example, 1000 × 10 ⁵ cm ³ / m ² · m ² · It is 24 hr · atm or less, and more preferably 500 × 10 ⁵ cm ³ / m ² · 24 hr · atm or less. The oxygen permeability is an index of gas permeability of the gas permeable film 1 and indicates a gas permeation amount in a unit time, a unit area, and a unit partial pressure difference. The oxygen permeability is measured by the method described in Examples described later. If the oxygen permeability of the gas permeable film 1 is not less than the above lower limit, the gas permeable film 1 can ensure excellent gas permeability. In order to set the oxygen permeability of the gas permeable film 1 to the above lower limit or more, as will be described later, the gas permeability and thickness of the porous layer 2 and the thickness of the nonporous layer 3 are adjusted as appropriate.

  The air permeability of the gas permeable film 1 is, for example, 90000 seconds / 100 mL or more, preferably 95000 seconds / 100 mL or more, more preferably 100000 seconds / 100 mL or more. The air permeability indicates the water permeability of the gas permeable film 1. The air permeability is measured as a Gurley value by the method described in Examples described later. If the air permeability is equal to or higher than the above lower limit, the gas permeable film 1 does not allow liquid such as water to pass therethrough, so that the gas permeable film 1 can be a film having excellent water resistance (liquid resistance). . In order to set the air permeability to the above lower limit or more, as will be described later, the thickness of the nonporous layer 3 is appropriately adjusted.

  The oxygen / nitrogen separation factor of the gas permeable film 1 is, for example, 3 or more, preferably 3.4 or more, and for example, 10 or less. The oxygen / nitrogen separation coefficient in the gas permeable film 1 is a ratio of oxygen permeability to nitrogen permeability (that is, oxygen permeability / nitrogen permeability). If the oxygen / nitrogen separation coefficient is high, oxygen is Compared with nitrogen, it can permeate efficiently. The oxygen / nitrogen separation factor of the gas permeable film 1 is measured by the method described in Examples described later. In order to set the oxygen / nitrogen separation coefficient of the gas permeable film 1 to the above lower limit or more, the type of the polymethylpentene resin used for the nonporous layer 3 is selected within the range described above, and the porous layer is further described later. 2 and the thickness of the nonporous layer 3 are adjusted.

  And the air permeability of the porous layer 2 is, for example, 10 seconds / 100 mL or more, further 10,000 seconds / 100 mL or less, and the thickness of the porous layer 2 is, for example, 10 μm or more and 1000 μm or less. By setting the thickness to, for example, 30 nm or more and less than 6 μm, each of the water pressure resistance, the gas permeability, the oxygen permeability, and the oxygen / nitrogen separation coefficient of the gas permeable film 1 can be set within the specific range described above. .

  And since this gas-permeable film 1 is equipped with the porous layer 2 and the non-porous layer 3 which consists of a polymethylpentene resin and has the thickness of a specific range, it is excellent in gas permeability.

  Furthermore, since the polyolefin resin of the porous layer 2 and the polymethylpentene resin of the nonporous layer 3 are both polyolefin, the adhesion between the porous layer 2 and the nonporous layer 3 is high, and the surface of the porous layer 2 The interfacial peeling between the porous layer 2 and the nonporous layer 3 can be suppressed while the nonporous layer 3 is reliably provided. Therefore, this gas permeable film 1 is excellent in durability.

  In particular, as shown in FIG. 2, when the non-porous layer 3 has an infiltrated portion 4, the infiltrated portion 4 has infiltrated into the non-porous layer 3. Due to the anchor effect, the adhesion between the porous layer 2 and the nonporous layer 3 can be further improved.

  Such a gas permeable film 1 is used in a field where excellent gas permeability and durability are required. Specifically, the gas permeable film 1 is a separation membrane used for production of ultrapure water, purification of chemicals, water treatment, etc., scaffold material for cell culture, culture container bottom material (medical use), agriculture / It is used as a waterproof and moisture-permeable film used for clothing, sanitary materials, packaging materials for electronic parts, and building materials for soundproofing and heat insulation.

<Modification>
In the above-described embodiment, the gas permeable film 1 includes the single porous layer 2 and the single non-porous layer 3. However, the present invention is not limited to the above embodiment, and any embodiment that does not hinder the effects of the present invention may be used. For example, although not shown, the gas permeable film 1 can include a single porous layer 2 and a plurality of (for example, two) non-porous layers 3. Specifically, the gas permeable film 1 can include a porous layer 2 and a non-porous layer 3 provided on each of the front and back surfaces thereof. Alternatively, the gas permeable film 1 can also include a plurality of (for example, two) porous layers 2 and a single non-porous layer 3 sandwiched between them in the thickness direction. Furthermore, the gas permeable film 1 can be configured as a multilayer film by alternately providing (stacking) a plurality of porous layers 2 and a plurality of non-porous layers 3 in the thickness direction. In addition, when the gas permeable film 1 is provided with two or more non-porous layers 3, the total thickness of several non-porous layers 3 exists in an above-described specific range.

  Hereinafter, the present invention will be described in more detail with reference to production examples, examples, and comparative examples, but the present invention is not limited thereto.

  Moreover, the numerical value of the Example shown below is described in embodiment mentioned above, and can be substituted to a corresponding numerical value (namely, upper limit value or lower limit value).

[Production of porous layer]
<Production Example 1>
Polypropylene resin (propylene homopolymer, “NOVATEC PP” manufactured by Nippon Polypro Co., Ltd.
FY6HA ”, density: 0.90 g / cm 3, MFR: 2.4 g / 10 min), and 3,9-bis [4- (N-cyclohexylcarbamoyl) phenyl] -2,4,8 as β crystal nucleating agent , 10-tetraoxaspiro [5.5] undecane (tetraoxaspiro compound). The β crystal nucleating agent is blended at a ratio of 0.2 part by mass with respect to 100 parts by mass of this polypropylene resin, and the same direction twin-screw extruder (caliber: 40 mmφ, L / D: 32) manufactured by Toshiba Machine Co., Ltd. is used. Then, after melting and mixing at a set temperature of 300 ° C., the strand was cooled and solidified in a water tank, and the strand was cut with a pelletizer to produce polypropylene resin pellets.

  Subsequently, the prepared pellets were extruded from the die of the same-direction twin screw extruder, and cooled and solidified with a casting roll at 124 ° C. to prepare a nonporous film. This non-porous film was stretched 4.6 times in the longitudinal direction at 100 ° C. using a longitudinal stretching machine. Thereby, a porous layer was obtained.

  The air permeability (Gurley value) of the porous layer was 14000 seconds / 100 mL.

[Production of gas permeable film]
<Example 1>
Polymethylpentene resin (4-methylpentene-1 / 1-hexene = 77.9 wt% / 22.1 wt%, melting point 225.3 ° C., heat of fusion 8.5 mJ / 95 parts by mass of cyclohexane (manufactured by Nacalai Tesque) mg) 5 parts by mass was added and stirred with a stirrer for about 3 hours to obtain a uniform solution as a coating solution.

  The coating liquid was applied to the surface of the porous layer obtained in Production Example 1 using a bar coater so that the thickness after drying was about 0.4 μm, and then dried at room temperature for 30 minutes. Subsequently, the film was stretched 2.1 times in the transverse direction at 150 ° C. using a transverse stretching machine, and then the porous film was heat-set at 153 ° C. Thereby, the gas-permeable film provided with a porous layer and a non-porous layer was obtained. The physical properties of the obtained gas permeable film were evaluated as follows, and the results are shown in Table 1.

<Example 2>
Except that polymethylpentene resin (4-methylpentene-1 / octadecene = 91 wt% / 9 wt%, melting point 223.9 ° C., heat of fusion 23.3 mJ / mg) was used as the polymer used for the nonporous layer, A gas permeable film was obtained in the same manner as in Example 1. The physical properties of the obtained gas permeable film were evaluated as follows, and the results are shown in Table 1.

<Comparative Example 1>
Example 1 except that polymethylpentene resin (4-methylpentene-1 / = 100 wt%, melting point 232.1 ° C., heat of fusion 39.0 mJ / mg) was used as the polymer used for the nonporous layer. Similarly, a gas permeable film was obtained. The physical properties of the obtained gas permeable film were evaluated as follows, and the results are shown in Table 1.

<Reference Example 1>
The porous layer obtained in Production Example 1 was stretched 2.1 times in the transverse direction at 150 ° C. by a transverse stretching machine, and then the porous film obtained by heat setting at 153 ° C. was used as the porous layer. Polymethylpentene resin (4-methylpentene-1 / 1-hexene = 77.9 wt% / 22.1 wt%, melting point 225.3 ° C., heat of fusion 8.5 mJ / 95 parts by weight of cyclohexane (manufactured by Nacalai Tesque) mg) 5 parts by mass was added and stirred with a stirrer for about 3 hours to obtain a uniform solution as a coating solution. A coating solution was applied to the surface of the obtained porous layer using a bar coater so that the thickness after drying was about 0.4 μm, and then dried at room temperature for 30 minutes. The physical properties of the obtained gas permeable film were evaluated as follows, and the results are shown in Table 1.

<Evaluation method>
(1) Total thickness of gas permeable film The total thickness of the obtained gas permeable film was measured in five unspecified areas in the plane of the gas permeable film with a dial gauge of 1/1000 mm, and the average value was obtained. Calculated.

(2) Thickness of non-porous layer and porous layer The thickness of the obtained non-porous layer was measured unspecifically at 10 points from an image obtained by observing the cross section of the produced gas-permeable film with a scanning electron microscope. It was calculated as a value.

  The thickness of the porous layer was calculated by subtracting the thickness of the nonporous layer from the thickness of the obtained gas permeable film.

(3) Interfacial peel strength A cellophane tape is applied to the surface of the non-porous layer of the obtained gas permeable film, cut into a strip shape having a width of 18 mm and a length of 40 mm, and air at a temperature of 23 ° C. using a tensile tester. The average peel strength when the 180 degree peel test was carried out three times at 200 mm / min at a tensile rate in the atmosphere was defined as the interfacial peel strength (N / 18 mm).

(4) Water pressure resistance The water pressure resistance of the obtained gas permeable film was measured according to JIS L1092 B method (high water pressure method) (2009).

(5) Oxygen permeability and nitrogen permeability The oxygen permeability and nitrogen permeability of the obtained gas permeable film were measured according to JIS K7126-2 (isobaric method) (2006).

(6) Air permeability (Gurley value)
The obtained air permeability was measured according to JIS P8117 (2009) using a Oken type air permeability meter. In addition, the result that the air permeability is 99999 seconds / 100 mL indicates that the measurement upper limit of the Oken type air permeability meter is reached, and the actual air permeability is higher than that.

(7) Oxygen / Nitrogen Separation Coefficient The oxygen / nitrogen separation coefficient of the obtained gas permeable film is defined as the ratio of oxygen permeability and nitrogen permeability obtained from (5) above (= oxygen permeability / nitrogen permeability). Calculated.

  As can be seen from Table 1, the gas permeable film of Example 1 has high oxygen permeability, high interfacial peel strength, and excellent gas permeability and durability. Moreover, the nonporous layer thickness is 0.2 μm, and the ratio of the nonporous layer in the gas permeable film is about 0.7%, and the thickness of the nonporous layer can be sufficiently reduced.

  In Example 2, a film having the same thickness as the non-porous layer of Example 1 having oxygen permeability and peel strength is obtained. However, oxygen permeability and peel strength are inferior to those of Example 1. This is because the heat of fusion of the resin used for the non-porous layer is larger than that of Example 1, and thus has the characteristic of being easily crystallized, which is considered to be due to a decrease in oxygen permeation performance due to the formation of a crystal structure. In addition, it is difficult for the non-porous layer to follow the stretching of the porous layer of the base material due to stretching after coating the non-porous layer, and as a result, peeling at the interface between the non-porous layer and the porous layer is likely to occur, and the peel strength is reduced. It is thought that he was invited.

  On the other hand, the gas permeable film of Comparative Example 1 had an air permeability of 2000 seconds / 100 mL, and pores were opened in the nonporous layer, so that the intended film could not be obtained. This is because the resin of the non-porous layer used in Comparative Example 2 has higher crystallinity than Comparative Example 1, and in the stretching after coating the non-porous layer, the substrate cannot follow the stretching, and part of the non-porous layer is This is thought to be due to tearing and formation of holes. Therefore, evaluation was not performed about oxygen permeability, peel strength, water pressure resistance, air permeability, and oxygen / nitrogen separation coefficient.

In the gas permeable film of Reference Example 1, the interfacial peel strength is comparable to that of Example 1.
However, the thickness of the nonporous layer is 0.4 μm, and the ratio of the nonporous layer in the gas permeable film is about 2.0%, which is about three times larger than that of Example 1.

  Gas permeable films include, for example, separation membranes used for the production of ultrapure water, purification of chemicals, water treatment, scaffolding materials for cell culture, culture container bottom materials (medical use), agriculture / clothing / sanitary materials -It is used as a waterproof and moisture-permeable film used as a packaging material for electronic parts and as a building material for soundproofing and heat insulation.

DESCRIPTION OF SYMBOLS 1 Gas-permeable film 2 Porous layer 3 Non-porous layer 4 Infiltration part 5 Micropore

Claims (6)

a porous layer made of a polypropylene resin containing a β crystal nucleating agent;
A polymethylpentene resin having a heat of fusion of 0.1 to 35 mJ / mg as a main component is provided on one surface in the thickness direction of the porous layer, and the thickness ratio of the nonporous layer to the film is 0.0001 or more, 0.0. a nonporous layer having a thickness of less than 3, characterized Rukoto such being stretched, the gas permeable film.   The gas-permeable film according to claim 1, wherein the nonporous layer has a thickness of 5 nm to 1 μm. ^3. The gas permeable film according to claim 1, wherein the oxygen permeability is 20 × 10 ⁵ cm ³ / m ² · 24 hr · atm or more.   The gas permeable film according to claim 1, wherein the porous layer is a porous film. A porous layer made of polyolefin resin;
A polymethylpentene resin having a heat of fusion of 0.1 to 35 mJ / mg as a main component is provided on one surface in the thickness direction of the porous layer, and the thickness ratio of the nonporous layer to the film is 0.0001 or more, 0.0. In a method for producing a gas permeable film comprising a non-porous layer having a thickness of less than 3,
Manufactured by stretching a solution prepared by dissolving a resin composition containing polymethylpentene as a main component and having a heat of fusion of 0.1 to 35 mJ / mg on one side in the thickness direction of the porous layer, and drying. The manufacturing method of the gas-permeable film characterized by the above-mentioned. A porous layer made of polypropylene resin;
A polymethylpentene resin having a heat of fusion of 0.1 to 35 mJ / mg as a main component is provided on one surface in the thickness direction of the porous layer, and the thickness ratio of the nonporous layer to the film is 0.0001 or more, 0.0. In a method for producing a gas permeable film comprising a non-porous layer having a thickness of less than 3,
Manufactured by stretching a solution prepared by dissolving a resin composition containing polymethylpentene as a main component and having a heat of fusion of 0.1 to 35 mJ / mg on one side in the thickness direction of the porous layer, and drying. The manufacturing method of the gas-permeable film characterized by the above-mentioned.

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