WO2015053228A1 - Permeable film, and method for producing same - Google Patents

Permeable film, and method for producing same Download PDF

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Publication number
WO2015053228A1
WO2015053228A1 PCT/JP2014/076716 JP2014076716W WO2015053228A1 WO 2015053228 A1 WO2015053228 A1 WO 2015053228A1 JP 2014076716 W JP2014076716 W JP 2014076716W WO 2015053228 A1 WO2015053228 A1 WO 2015053228A1
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WO
WIPO (PCT)
Prior art keywords
glass fiber
binder resin
fiber fabric
breathable film
air permeability
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PCT/JP2014/076716
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French (fr)
Japanese (ja)
Inventor
山田　宗紀
健太 柴田
直史 藤岡
耕 竹内
朗 繁田
寿史朗 江口
雅弘 細田
良彰 越後
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ユニチカ株式会社
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Application filed by ユニチカ株式会社 filed Critical ユニチカ株式会社
Priority to JP2015541571A priority Critical patent/JP6562839B2/en
Priority to CN201480054720.4A priority patent/CN105593431B/en
Publication of WO2015053228A1 publication Critical patent/WO2015053228A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/52—Separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/431—Inorganic material
    • H01M50/434—Ceramics
    • H01M50/437—Glass
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/44—Fibrous material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/454—Separators, membranes or diaphragms characterised by the material having a layered structure comprising a non-fibrous layer and a fibrous layer superimposed on one another
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a breathable film, and more particularly to a breathable film useful as a separator for lithium secondary batteries and capacitors, a substrate material for electronic devices such as electronic substrates, chip packages and circuit boards, a liquid or gas filter, and the like. .
  • the breathable film is widely used as a separator for lithium secondary batteries and capacitors, for example. It is also widely used as a substrate material for electronic devices such as electronic substrates, chip packages and circuit boards, and liquid and gas filters.
  • a breathable film made of polyolefin is usually used as a separator for lithium secondary batteries and capacitors. These polyolefin separators are likely to shrink or break at a high temperature of about 150 ° C., and in some cases, the positive electrode and the negative electrode may be in direct contact with each other, causing a short circuit, and abnormal heat generation due to the short circuit cannot be suppressed. is there. Accordingly, there is a need for a separator that can ensure sufficient insulation even at such high temperatures.
  • the rigidity of the nonwoven fabric itself as the base material is low, and the shape stability at high temperature is not always sufficient.
  • the rigidity is low and there is a possibility of causing a short circuit, so that it cannot be used as a separator.
  • the uniformity of the pores formed is low, and thus air bubbles may occur. If air spots occur, problems such as self-discharge occur, so that it cannot be used as a separator.
  • Patent Documents 3 and 4 propose a separator made of a glass fiber fabric impregnated with a binder resin having a microporous structure formed by a phase separation method.
  • a phase separation method for example, a uniform solution prepared by mixing a binder resin and a solvent at a high temperature is formed into a film by a T-die method, an inflation method, etc., and then cooled to cause phase separation, and the solvent is separated from another volatile solvent.
  • a microporous structure is formed by extracting and removing with.
  • such a method has a problem that pinholes are easily generated in the glass fiber fabric impregnated with the binder resin and the uniform air permeability is impaired.
  • an object of the present invention is to provide a breathable film having excellent mechanical properties such as rigidity and heat resistance such as shape stability at high temperature and uniform breathability, and a method for producing the same.
  • the present inventors have solved the above problems by using a breathable film in which a glass fiber fabric composed of continuous long fibers is made into a specific structure using a binder resin. As a result, the present invention has been reached.
  • the present invention has the following gist.
  • the air-permeable film as described above having a ventilation spot of ⁇ 25% or less in the variation rate of the air permeability.
  • a breathable film having excellent mechanical properties such as rigidity and heat resistance such as shape stability at high temperature and uniform breathability can be provided.
  • the breathable film of the present invention is also useful as a separator for power storage devices such as capacitors and capacitors, and as a substrate material for electronic devices such as electronic substrates, chip packages and circuit boards.
  • FIG. 2 is a photomicrograph showing the surface state of a breathable film finally obtained in Example 1.
  • FIG. It is a microscope picture showing the surface state of the binder resin impregnation glass fiber fabric obtained before the resumption fiber process in the comparative example 1.
  • the breathable film of the present invention is a breathable film in which a glass fiber fabric is impregnated with a binder resin.
  • the glass fiber woven fabric used in the present invention is a woven fabric formed using yarns composed of a plurality of glass fibers.
  • the composition of the glass fiber of the glass fiber fabric is not limited, such as alkali-free (E) glass, low dielectric (D) glass, alkali (A) glass, etc., but glass fiber fabric made from alkali-free glass is preferred.
  • the preferred thickness of this glass fiber fabric is 50 ⁇ m or less, more preferably 30 ⁇ m or less, and even more preferably 25 ⁇ m or less.
  • the lower limit of the thickness of the glass fiber fabric is not particularly limited, but the thickness is usually 5 ⁇ m or more, preferably 10 ⁇ m or more.
  • the thickness of the glass fiber fabric is measured based on JIS K7130-1992.
  • the average diameter of the glass fiber filaments constituting the glass fiber fabric is preferably 5 ⁇ m or less. Although the lower limit of the average diameter of the glass fiber filament is not particularly limited, the average diameter is usually 1 ⁇ m or more, preferably 3 ⁇ m or more.
  • the yarn forming the glass fiber fabric is subjected to a fiber opening treatment by a method disclosed in, for example, Japanese Patent No. 4192054.
  • a known method may be used.
  • the opening method by the pressure of a fluid such as water, the opening method by high-frequency vibration using a liquid as a medium, or the opening method by processing by pressurization with a roll. Etc.
  • the glass fiber fabric can be easily impregnated with the resin.
  • the woven structure of the glass fiber woven fabric may be any of plain weave, twill weave, satin weave, etc., but plain woven glass fiber woven fabric is preferred.
  • the glass fiber fabric is preferably surface-treated with a silane coupling agent or the like in order to increase the interface affinity with the binder resin.
  • silane coupling agents vinyltrichlorosilane, vinyltriethoxysilane, vinyltris ( ⁇ -methoxyethoxy) silane, ⁇ -methacryloxypropyltrimethoxysilane, ⁇ -aminopropyltriethoxysilane, ⁇ -anilinopropyltrimethoxysilane N- ⁇ -aminoethyl- ⁇ -aminopropyltrimethoxysilane, N-vinylbenzyl-aminoethyl- ⁇ -aminopropyltrimethoxysilane (hydrochloride), ⁇ -glycidoxypropyltrimethoxysilane, ⁇ - (3 , 4-epoxycyclohexyl) ethyltrimethoxysilane, ⁇ -mercaptopropyltrimethoxy
  • the silane coupling agent is preferably N-vinylbenzyl-aminoethyl- ⁇ -aminopropyltrimethoxysilane (hydrochloride), ⁇ -anilinopropyltrimethoxysilane, or a mixture thereof.
  • the surface treatment using the silane coupling agent is performed by using glass fiber or a woven fabric thereof in a solution in which the silane coupling agent is usually dissolved at a concentration of about 0.01 to 20% by mass, preferably about 0.1 to 5% by mass. Is immersed and hydrolyzed as necessary, followed by heating.
  • the air permeability of the glass fiber fabric used in the present invention is less than 1 second / 100 cc as a Gurley value based on JIS standard P8117.
  • the basis weight of the glass fiber fabric is usually 10 to 40 g / m 2 , preferably 15 to 35 g / m 2 .
  • the surface (both front and back surfaces) of the glass fiber fabric is entirely covered with a binder resin.
  • Whether or not the entire surface is covered with the binder resin can be determined, for example, by acquiring digital images of the front surface (both front and back surfaces) with a digital microscope (SEM magnification of 300 times). If no pores having an area of 10 ⁇ m 2 or more are observed in this image, it is determined that the entire surface is covered with a binder resin. Conversely, if one or more pores having an area of 10 ⁇ m 2 or more are observed in this image, it is determined that the entire surface is not covered with the binder resin. When one or more pores having an area of 10 ⁇ m 2 or more are observed, problems such as self-discharge occur when the breathable film is used as a separator for a lithium secondary battery.
  • the pore is a region where the binder resin is not present on the surface appearance by a digital image.
  • a non-impregnated region may be locally generated.
  • Such a region where the binder resin is not present can be clearly distinguished from a region where the binder resin around it is present on the digital image based on differences in color, thickness, and the like.
  • the air permeable film of the present invention has good air permeability even though the surface of the glass fiber fabric is entirely covered with the binder resin. This is presumably because uniform and fine linear pores are formed between the constituent fibers of the yarn of the glass fiber fabric.
  • the surface of the glass fiber fabric is entirely covered with the binder resin, and the binder resin is sufficiently filled between the plurality of glass fibers constituting the yarn of the glass fiber fabric. Yes.
  • pores are formed between the glass fibers substantially in parallel with the glass fibers, and therefore it is considered that the glass fibers have good air permeability.
  • the type of binder resin used in the present invention is not limited, but examples thereof include modified polyolefin, polyvinylidene fluoride, polyacrylonitrile, polyethylene oxide, polymethyl methacrylate, polyimide, polyamide, polyamideimide, and the like. It can also be used. Among these, a modified polyolefin resin is particularly preferable from the viewpoint of adhesiveness with a glass fiber fabric.
  • the modified polyolefin resin it is preferable to use a copolymer having a structure in which an unsaturated carboxylic acid is randomly copolymerized or graft copolymerized with polyolefin.
  • polystyrene resin examples include low density polyethylene, high density polyethylene, polypropylene, ethylene-butene-1 copolymer, ethylene-propylene copolymer, polybutadiene and the like.
  • the unsaturated carboxylic acid is an unsaturated carboxylic acid having at least one radical polymerizable bond (particularly a double bond) and at least one carboxyl group in one molecule, and an anhydride thereof. Specific examples thereof include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, aconitic acid, aconitic anhydride, fumaric acid, crotonic acid, citraconic acid and the like.
  • the modified polyolefin resin may contain two or more kinds of compounds as unsaturated carboxylic acid. Maleic anhydride, acrylic acid, and methacrylic acid are preferable from the viewpoint of easy introduction into a polyolefin resin and securing adhesion to a glass fiber fabric treated with the silane coupling agent.
  • the modified polyolefin resin can be produced by polymerizing a predetermined monomer by a known method such as an interfacial polymerization method, a solution polymerization method, a suspension polymerization method, or a commercially available product using water as a main dispersion medium. It can also be obtained in the form of an aqueous emulsion or a solution containing an organic solvent as a main solvent.
  • the modified polyolefin resin is preferably in the form of an aqueous emulsion from the viewpoint of environmental compatibility.
  • An aqueous emulsion of a modified polyolefin resin can be produced, for example, by a method described in Japanese Patent No. 3699935, Japanese Patent No. 3759160, and the like.
  • Such a commercial product is an aqueous emulsion of a modified polyolefin resin.
  • modified polyolefin resin two or more kinds of modified polyolefin resins having different compositions, molecular weights and / or melting points may be used. At this time, each of the two or more kinds of modified polyolefin resins may be in the above-mentioned range.
  • a crosslinking agent is preferably blended in order to improve heat resistance.
  • the cross-linking agent is a cross-linking agent for a binder resin, particularly a modified polyolefin resin.
  • a binder resin particularly a modified polyolefin resin.
  • Including a plastic or thermosetting polymer include oxazoline-based, melamine-based, and epoxy-based crosslinking agents, and oxazoline-based crosslinking agents are preferable.
  • the oxazoline-based crosslinking agent is an organic compound (including a thermoplastic or thermosetting polymer) having two or more oxazoline groups in one molecule.
  • An oxazoline-based crosslinking agent is available as WS-700 manufactured by Nippon Shokubai Co., Ltd.
  • the amount of the cross-linking agent is selected from the viewpoint of ensuring a sufficiently sufficient amount of the binder resin to be impregnated and forming linear pores more sufficiently between the constituent fibers of the yarn.
  • the content is preferably 3 to 30% by mass, more preferably 5 to 20% by mass, based on the resin, particularly the modified polyolefin resin.
  • the total compounding quantity should just be in the range of the said compounding quantity.
  • the impregnation amount of the binder resin is preferably 5 to 40% by mass, more preferably 10 to 30% by mass with respect to the glass fiber fabric.
  • the total impregnation amount of the binder resin and the crosslinking agent is the impregnation amount of the binder resin.
  • the air permeable film of the present invention has a Gurley value (JIS standard P8117) of 1000 seconds / 100 cc or less and 1 second / 100 cc or more, and a preferable air permeability is 600 seconds / 100 cc or less and 100 seconds / 100 cc or more.
  • the expression “breathability” is used in the sense of having such air permeability.
  • the air permeability can be controlled by adjusting the amount of the binder resin impregnated. The air permeability increases as the amount of the binder resin impregnated increases.
  • the breathing spots are preferably ⁇ 25% or less, more preferably ⁇ 20% or less with respect to the average value of the Gurley values (JIS standard P8117) at 10 points in the breathable film. Is more preferable. By doing so, uniform air permeability is ensured.
  • the air spots are secured by using a glass fiber fabric as a base material and performing a re-fibering process described later.
  • the shape retention rate at 150 ° C. is preferably 98% or more, and more preferably 99% or more.
  • the shape retention rate at 150 ° C. was determined by cutting the breathable film into 8 cm ⁇ 8 cm, and writing a 6 cm ⁇ 6 cm square in the breathable film in a 150 ° C. oven for 30 minutes and heating. It can be calculated by measuring the line spacing of the heated film. By doing in this way, it can use suitably as a separator for lithium secondary batteries which has heat resistance, for example.
  • the heat resistance is ensured by using a glass fiber fabric as a substrate.
  • the breathable film of the present invention can be easily obtained by the following three steps, for example.
  • the binder resin is made into a solution or an emulsion, and an impregnating liquid for impregnating the glass fiber fabric (hereinafter sometimes simply referred to as “impregnating liquid”) is prepared.
  • the impregnating liquid may contain the above-mentioned crosslinking agent, organic polymer fine particles such as polyolefin resin particles, and fine particles composed of an inorganic oxide such as alumina.
  • an emulsion stabilizer, various surfactants, etc. may be mix
  • the binder resin concentration of the impregnating liquid is not particularly limited. For example, when the binder resin concentration is too thin to achieve the desired amount of impregnation of the binder resin, the impregnation or application and drying in the second step may be repeated.
  • ⁇ Second step> The glass fiber fabric is impregnated or coated with the impregnation liquid, and then dried to remove the solvent or dispersion medium.
  • the impregnating liquid is filled in the voids of the glass fiber fabric by impregnation or coating.
  • Specific methods include, for example, a dip coating method in which a glass fiber fabric is dipped in the solution or emulsion and then pulled up and squeezed using a mangle or the like, or the solution or emulsion is applied to a support by a die or a coating roll.
  • a known coating method such as a transfer type coating method for transferring is suitably used.
  • the solution or emulsion may be simultaneously applied to the front and back surfaces of the glass fiber fabric.
  • the drying temperature for removing the solvent or the dispersion medium is preferably 50 to 150 ° C.
  • the air permeability of the glass fiber fabric after impregnation with the binder resin is once lost.
  • the amount of the binder resin impregnated is 15 to 35% by mass, preferably 20 to 30% by mass with respect to the glass fiber fabric. Good. Thereby, the surface of the glass fiber fabric is entirely covered with the binder resin, and the air permeability can be lost.
  • “loss of air permeability” is determined by whether or not the Gurley value is more than 2000 seconds / 100 cc. That is, when the Gurley value is more than 2000 seconds / 100 cc, it is determined that the air permeability is lost, and it can be confirmed that the surface is entirely covered with the binder resin without any pinholes or the like. If the impregnation amount of the binder resin in this step is too small, the surface of the finally obtained breathable film is not sufficiently covered with the binder resin, so when the breathable film is used as a separator for a lithium secondary battery, Problems such as self-discharge occur.
  • the amount of the binder resin impregnated in this step is too large, the air permeability of the air permeable film will not be sufficiently lowered even if the re-opening fiber treatment described later is performed, so that it cannot be used as a separator for a lithium secondary battery.
  • the total impregnation amount of the binder resin and the crosslinking agent is the impregnation amount of the binder resin.
  • ⁇ Third step> The binder resin-impregnated glass fiber fabric whose air permeability has been lost is subjected to a re-fiber treatment.
  • a binder resin-impregnated glass fiber fabric a binder resin is impregnated between yarn constituent fibers, and a plurality of constituent fibers are integrated.
  • the restart fiber process is a process in which such integrated fibers are at least partially loosened to form pores substantially parallel to the fibers between the constituent fibers. By doing so, uniform linear pores are formed between the constituent fibers of the yarn of the glass fiber fabric, and the air permeability is restored, and the uniform air permeability of the binder resin-impregnated glass fiber fabric can be ensured.
  • the method for resuming the fiber is not particularly limited as long as linear pores are formed between the constituent fibers by applying vibration to the binder resin-impregnated glass fiber fabric.
  • vibration treatment that imparts vibration in water is preferable.
  • a vibration treatment device that imparts vibration by rotating a rotor having unevenness in water.
  • an FV washing machine manufactured by Komatsubara Co., Ltd. can be exemplified.
  • the strength of the vibration applied is not particularly limited as long as linear pores are formed between the constituent fibers.
  • the strength of vibration applied in water is preferably 400 to 1000 rpm when the vibration is applied by rotation of an uneven rotor.
  • the treatment temperature and treatment time of the resuming fiber treatment are not particularly limited as long as the predetermined air permeability described above can be obtained.
  • the treatment temperature such as the temperature of water is usually 10 to 80 ° C.
  • the air permeability of the air permeable film can be controlled by adjusting the treatment temperature. The higher the processing temperature, the lower the air permeability of the breathable film.
  • the processing time such as vibration applying time is usually 0.5 to 10 minutes.
  • the air permeability of the air permeable film can be controlled by adjusting the treatment time. The longer the treatment time, the lower the air permeability of the breathable film.
  • the glass fiber fabric constituting the breathable film of the present invention has very good shape stability at high temperature, is composed of continuous long fibers, and has high rigidity.
  • such a glass fiber woven fabric is usually produced by a fiber opening treatment, and the glass fiber woven fabric is impregnated with a binder resin to temporarily lose air permeability (second step). Thereafter, resuming fiber processing is performed (third step). For this reason, the breathable film of the present invention has no pinholes, has uniform breathability, and has high mechanical properties and heat resistance.
  • the breathable film of the present invention is suitably used as, for example, a lithium secondary battery separator, a capacitor separator, a substrate material for electronic devices such as an electronic substrate, a chip package and a circuit board, and a liquid and gas filter. can do.
  • the properties of the breathable film were evaluated by the following methods.
  • Thickness (unit: ⁇ m) The thickness of the breathable film was measured based on JIS K7130-1992.
  • Air permeability (unit: seconds / 100cc)
  • the air permeability (Gurley value) of the air permeable film was measured based on JIS P8117.
  • Ventilation spots The air permeability at 10 points in the breathable film was measured, the deviation rate from the average value was calculated, and the maximum value or the minimum value was taken as the variation rate. When the variation rate was ⁇ 20% or less, the uniformity was judged to be good, and when it was more than ⁇ 20%, the uniformity was judged to be poor.
  • Example 1 A plain-woven glass fiber fabric (weighing 24 g / m 2 , thickness 20 ⁇ m, glass fiber diameter ⁇ 4.1 ⁇ m ⁇ 100 bundle, air permeability less than 1 second / 100 cc, fiber opening treatment and silane coupling treatment) was prepared. A photomicrograph of the glass fiber fabric surface is shown in FIG. On the other hand, as the modified polyolefin resin for impregnation, “Arrobase” (trade name) product number SB-1200, which is an aqueous emulsion of a modified polyolefin resin, was prepared.
  • “Arrobase” trade name
  • an oxazoline-based crosslinking agent (WS-700 manufactured by Nippon Shokubai Co., Ltd.) was added and stirred to prepare an impregnating solution as a uniform dispersion.
  • the blending amount of the oxazoline-based crosslinking agent was 5.9% by mass with respect to the modified polyolefin-based resin (solid content).
  • Second step The glass fiber fabric is dipped in the appropriately diluted impregnation solution, squeezed with a mangle, and then dried at 80 ° C. for 90 seconds to obtain 20.0% by mass of a binder resin based on the glass fiber fabric.
  • An impregnated glass fiber fabric was obtained.
  • the air permeability of this glass fiber fabric was over 2000 seconds / 100 cc, and it was confirmed that the air permeability was lost.
  • the whole surface was coat
  • a photomicrograph of the surface of the binder resin-impregnated glass fiber fabric is shown in FIG.
  • Example 2 A breathable film was obtained in the same manner as in Example 1 except that the amount of the binder resin impregnated in the second step was 17% by mass.
  • the air permeability of the glass fiber fabric obtained in the second step was over 2000 seconds / 100 cc, and it was confirmed that the air permeability was lost.
  • the air permeable film obtained in the third step had an air permeability of 256 sec / 100 cc and air spots of 17.5%, confirming good and uniform air permeability.
  • the heating shape maintenance factor of this air permeable film was as good as 98.8%.
  • the total impregnation amount of the binder resin and the crosslinking agent in the finally obtained breathable film was 17% by mass with respect to the glass fiber fabric. When the surface covering state of the breathable film was observed, the entire surface was covered with a binder resin.
  • Example 3 A breathable film was obtained in the same manner as in Example 1 except that the binder resin impregnation amount was 23% by mass in the second step.
  • the air permeability of the glass fiber fabric obtained in the second step was over 2000 seconds / 100 cc, and it was confirmed that the air permeability was lost.
  • the air permeable film obtained in the third step had an air permeability of 528 sec / 100 cc and air spots of 14.3%, confirming good and uniform air permeability.
  • the heating shape maintenance factor of this air permeable film was as favorable as 99.3%.
  • the total impregnation amount of the binder resin and the crosslinking agent in the finally obtained breathable film was 23% by mass with respect to the glass fiber fabric. When the surface covering state of the breathable film was observed, the entire surface was covered with a binder resin.
  • Example 1 In the second step, the binder resin was impregnated in the same manner as in Example 1 except that the amount of the binder resin impregnated was 10% by mass.
  • the air permeability before the reopening fiber treatment was 156 seconds / 100 cc, and the air permeability was not lost.
  • the surface covering state of the binder resin-impregnated glass fiber fabric was observed, two pores having an area of 10 ⁇ m 2 or more were observed, and it was determined that the surface was not entirely covered with the binder resin.
  • a photomicrograph of the surface of this binder resin-impregnated glass fiber fabric is shown in FIG. Further, the air bubble unevenness of the binder resin-impregnated glass fiber fabric was 35.2%, and the air permeability was not uniform.
  • the breathable film of the present invention is excellent in breathability, has a shape retention rate of 98% or more when heated at 150 ° C., and has a Gurley value fluctuation rate of ⁇ 25% or less. In particular, it is ⁇ 20% or less. Therefore, the breathable film of the present invention is a substrate material for electronic devices such as lithium secondary batteries and capacitor separators, electronic substrates, chip packages and circuit boards that require heat resistance (heat deformation resistance) and uniform breathability. And as a liquid and gas filter and the like.
  • the air-permeable film of the present invention is useful as a substrate material for electronic devices such as lithium secondary batteries and capacitor separators, electronic substrates, chip packages and circuit boards, and liquid and gas filters.

Abstract

The present invention provides a permeable film which has even permeability and which exhibits excellent kinetic properties such as durability, and heat resistant properties such as shape stability at high temperatures. The present invention also provides a method for producing said permeable film. The present invention is a permeable film in which a glass fiber fabric is impregnated with a binder resin, the permeable film being characterized by having the following features: (1) the binder resin covers the entire surface of the glass fiber fabric; and (2) the permeability of the permeable film is 1000 sec/100 cc or less and 1 sec/100 cc or more in Gurley values (JIS standard P8117). The present invention is also a method for producing said permeable film, whereby the permeability of a glass fiber fabric is first eliminated by impregnating the glass fiber fabric that was opened with a binder resin, and then re-opening the glass fiber fabric.

Description

通気性フィルムおよびその製造方法Breathable film and method for producing the same
　本発明は、通気性フィルムに関し、詳しくは、リチウム二次電池およびキャパシタのセパレータ、電子基板、チップパッケージおよび回路ボード等の電子デバイス用基板材料、液体や気体のフィルタ等として有用な通気性フィルムに関する。 The present invention relates to a breathable film, and more particularly to a breathable film useful as a separator for lithium secondary batteries and capacitors, a substrate material for electronic devices such as electronic substrates, chip packages and circuit boards, a liquid or gas filter, and the like. .
　通気性フィルムは、例えばリチウム二次電池およびキャパシタのセパレータとして、広く使用されている。また、電子基板、チップパッケージおよび回路ボード等の電子デバイス用基板材料、ならびに液体および気体のフィルタ等としても広く利用されている。 The breathable film is widely used as a separator for lithium secondary batteries and capacitors, for example. It is also widely used as a substrate material for electronic devices such as electronic substrates, chip packages and circuit boards, and liquid and gas filters.
　リチウム二次電池やキャパシタのセパレータとしては、通常、ポリオレフィンからなる通気性フィルムが用いられる。これらポリオレフィン製セパレータは、１５０℃程度の高温になると収縮や破断が起こりやすいので、場合によっては、正極と負極が直接接触して、短絡を起こすおそれがあり、短絡による異常発熱を抑制できないことがある。従い、このような高温でも充分に絶縁性が確保できるセパレータが求められている。 A breathable film made of polyolefin is usually used as a separator for lithium secondary batteries and capacitors. These polyolefin separators are likely to shrink or break at a high temperature of about 150 ° C., and in some cases, the positive electrode and the negative electrode may be in direct contact with each other, causing a short circuit, and abnormal heat generation due to the short circuit cannot be suppressed. is there. Accordingly, there is a need for a separator that can ensure sufficient insulation even at such high temperatures.
　このような問題を解決する方法として、ポリエステル製不織布やアルミナ短繊維からなる不織布等に、フィラーを配合したバインダ樹脂を含浸することにより、高温での形状安定性が付与されたセパレータが提案されている（例えば、特許文献１、２）。 As a method for solving such a problem, a separator has been proposed in which shape stability at high temperature is imparted by impregnating a binder resin blended with a filler into a nonwoven fabric made of polyester or short alumina fibers. (For example, Patent Documents 1 and 2).
　しかしながら、このような方法では、基材である不織布そのものの剛性が低く、高温での形状安定性は必ずしも充分ではなかった。得られた通気性フィルムをリチウム二次電池やキャパシタのセパレータとして使用する場合、剛性が低く、短絡を起こすおそれがあり、セパレータとしての使用に耐えない。また不織布を用いた場合、形成される気孔の均一性が低いので、通気斑を生じることがあった。通気斑が生じると、自己放電等の問題が起こるので、セパレータとしての使用に耐えない。 However, according to such a method, the rigidity of the nonwoven fabric itself as the base material is low, and the shape stability at high temperature is not always sufficient. When the obtained air permeable film is used as a separator for a lithium secondary battery or a capacitor, the rigidity is low and there is a possibility of causing a short circuit, so that it cannot be used as a separator. Moreover, when a nonwoven fabric is used, the uniformity of the pores formed is low, and thus air bubbles may occur. If air spots occur, problems such as self-discharge occur, so that it cannot be used as a separator.
　このような問題を解消する方法として、高温での形状安定性が良好で、かつ気孔の均一性が良好な、ガラス繊維織物を用いたセパレータが提案されている。例えば、特許文献３，４には、相分離法により微多孔構造が形成されたバインダ樹脂を含浸したガラス繊維織物からなるセパレータが提案されている。相分離法では、例えば、バインダ樹脂と溶剤を高温で混合して調製した均一溶液を、Ｔダイ法、インフレーション法等でフイルム化した後、冷却して相分離させ、溶剤を別の揮発性溶剤で抽出除去することにより、微多孔構造が形成される。しかしながら、このような方法においては、バインダ樹脂が含浸されたガラス繊維織物にピンホール等が発生しやすく均一な通気性が損なわれるという問題があった。 As a method for solving such a problem, a separator using a glass fiber fabric that has good shape stability at high temperatures and good pore uniformity has been proposed. For example, Patent Documents 3 and 4 propose a separator made of a glass fiber fabric impregnated with a binder resin having a microporous structure formed by a phase separation method. In the phase separation method, for example, a uniform solution prepared by mixing a binder resin and a solvent at a high temperature is formed into a film by a T-die method, an inflation method, etc., and then cooled to cause phase separation, and the solvent is separated from another volatile solvent. A microporous structure is formed by extracting and removing with. However, such a method has a problem that pinholes are easily generated in the glass fiber fabric impregnated with the binder resin and the uniform air permeability is impaired.
特許第５２１３００７号公報Japanese Patent No. 5213007 特許第４７４３７４７号公報Japanese Patent No. 4743747 特開２００４－２６９５７９号公報JP 2004-269579 A ＷＯ２００４／０１９４３３WO2004 / 019433
　そこで、本発明の目的は、剛性等の力学的特性および高温での形状安定性等の耐熱性に優れ、かつ均一な通気性を有する通気性フィルムおよびその製造方法を提供することにある。 Therefore, an object of the present invention is to provide a breathable film having excellent mechanical properties such as rigidity and heat resistance such as shape stability at high temperature and uniform breathability, and a method for producing the same.
　本発明者らは、前記課題を解決すべく鋭意検討した結果、連続した長繊維からなるガラス繊維織物を、バインダ樹脂を用いて特定の構造とした通気性フィルムを用いることにより、前記課題が解決されることを見出し、本発明に到達した。 As a result of intensive studies to solve the above problems, the present inventors have solved the above problems by using a breathable film in which a glass fiber fabric composed of continuous long fibers is made into a specific structure using a binder resin. As a result, the present invention has been reached.
　すなわち、本発明は、下記を要旨とするものである。
　ガラス繊維織物にバインダ樹脂が含浸された通気性フィルムであって、以下の特徴を有する通気性フィルム：
１）前記ガラス繊維織物の表面がバインダ樹脂で全面的に被覆されている；
２）前記通気性フィルムの通気度が、ガーレ値（ＪＩＳ規格Ｐ８１１７）で１０００秒／１００ｃｃ以下１秒／１００ｃｃ以上である。 That is, the present invention has the following gist.
A breathable film in which a glass fiber fabric is impregnated with a binder resin and has the following characteristics:
1) The surface of the glass fiber fabric is entirely covered with a binder resin;
2) The air permeability of the air permeable film is 1000 seconds / 100 cc or less and 1 second / 100 cc or more in terms of Gurley value (JIS standard P8117).
　通気度の変動率で±２５％以下の通気斑を有する前記の通気性フィルム。 The air-permeable film as described above having a ventilation spot of ± 25% or less in the variation rate of the air permeability.
　バインダ樹脂が変性ポリオレフィン系樹脂である前記の通気性フィルム。 The air-permeable film as described above, wherein the binder resin is a modified polyolefin resin.
　変性ポリオレフィン系樹脂中に架橋剤が配合されている前記の通気性フィルム。 The breathable film described above, wherein a cross-linking agent is blended in the modified polyolefin resin.
　開繊処理された複数のガラス繊維からなる糸を用いて形成されたガラス繊維織物にバインダ樹脂を含浸して、ガラス繊維織物の通気性を一旦消失させた後、再開繊処理することを特徴とする前記通気性フィルムの製造方法。 It is characterized by impregnating a binder resin into a glass fiber woven fabric formed using a plurality of glass fibers that have been subjected to fiber opening treatment, once the breathability of the glass fiber woven fabric has been lost, and then re-opening the fiber. A method for producing the breathable film.
　再開繊処理が水中での振動処理である前記の通気性フィルムの製造方法。 The method for producing a breathable film as described above, wherein the resuming fiber treatment is vibration treatment in water.
　本発明によれば、剛性等の力学的特性および高温での形状安定性等の耐熱性に優れ、かつ均一な通気性を有する通気性フィルムを提供することができる。本発明の通気性フィルムは、キャパシタおよびコンデンサ等の蓄電デバイス用セパレータ、および電子基板、チップパッケージおよび回路ボード等の電子デバイス用基板材料としても有用である。 According to the present invention, a breathable film having excellent mechanical properties such as rigidity and heat resistance such as shape stability at high temperature and uniform breathability can be provided. The breathable film of the present invention is also useful as a separator for power storage devices such as capacitors and capacitors, and as a substrate material for electronic devices such as electronic substrates, chip packages and circuit boards.
実施例および比較例において使用されたガラス繊維織物の表面状態を表す顕微鏡写真である。It is a microscope picture showing the surface state of the glass fiber fabric used in the Example and the comparative example. 実施例１において再開繊処理前に得られたバインダ樹脂含浸ガラス繊維織物の表面状態を表す顕微鏡写真である。It is a microscope picture showing the surface state of the binder resin impregnation glass fiber fabric obtained before the reopening fiber processing in Example 1. FIG. 実施例１において最終的に得られた通気性フィルムの表面状態を表す顕微鏡写真である。2 is a photomicrograph showing the surface state of a breathable film finally obtained in Example 1. FIG. 比較例１において再開繊処理前に得られたバインダ樹脂含浸ガラス繊維織物の表面状態を表す顕微鏡写真である。It is a microscope picture showing the surface state of the binder resin impregnation glass fiber fabric obtained before the resumption fiber process in the comparative example 1.
　以下、本発明について詳細に説明する。 Hereinafter, the present invention will be described in detail.
［通気性フィルム］
　本発明の通気性フィルムは、ガラス繊維織物にバインダ樹脂が含浸された通気性フィルムである。 [Breathable film]
The breathable film of the present invention is a breathable film in which a glass fiber fabric is impregnated with a binder resin.
　本発明において使用されるガラス繊維織物は、複数のガラス繊維からなる糸を用いて形成された織物である。ガラス繊維織物のガラス繊維の組成は、無アルカリ（Ｅ）ガラス、低誘電（Ｄ）ガラス、アルカリ（Ａ）ガラス等制限はないが、無アルカリガラスを原料とするガラス繊維織物が好ましい。このガラス繊維織物の好ましい厚みは５０μｍ以下であり、３０μｍ以下であることがより好ましく、２５μｍ以下であることが更に好ましい。ガラス繊維織物の厚みの下限値は特に限定されないが、当該厚みは通常、５μｍ以上であり、好ましくは１０μｍ以上である。ガラス繊維織物の厚みは、ＪＩＳ　Ｋ７１３０－１９９２に基づいて測定される。 The glass fiber woven fabric used in the present invention is a woven fabric formed using yarns composed of a plurality of glass fibers. The composition of the glass fiber of the glass fiber fabric is not limited, such as alkali-free (E) glass, low dielectric (D) glass, alkali (A) glass, etc., but glass fiber fabric made from alkali-free glass is preferred. The preferred thickness of this glass fiber fabric is 50 μm or less, more preferably 30 μm or less, and even more preferably 25 μm or less. The lower limit of the thickness of the glass fiber fabric is not particularly limited, but the thickness is usually 5 μm or more, preferably 10 μm or more. The thickness of the glass fiber fabric is measured based on JIS K7130-1992.
　ガラス繊維織物を構成するガラス繊維フィラメントの平均径は５μｍ以下が好ましい。ガラス繊維フィラメントの平均径の下限値は特に限定されないが、当該平均径は通常、１μｍ以上であり、好ましくは３μｍ以上である。 The average diameter of the glass fiber filaments constituting the glass fiber fabric is preferably 5 μm or less. Although the lower limit of the average diameter of the glass fiber filament is not particularly limited, the average diameter is usually 1 μm or more, preferably 3 μm or more.
　ガラス繊維織物を形成する糸は、例えば特許第４１９２０５４号公報に開示されたような方法で開繊処理されていることが好ましい。開繊方法としては、公知の方法であってよく、例えば水等の流体の圧力による開繊方法、液体を媒体とした高周波の振動による開繊方法、ロールによる加圧での加工による開繊方法等が挙げられる。このように開繊することにより、ガラス繊維織物への樹脂含浸を容易に行うことができる。 It is preferable that the yarn forming the glass fiber fabric is subjected to a fiber opening treatment by a method disclosed in, for example, Japanese Patent No. 4192054. As the opening method, a known method may be used. For example, the opening method by the pressure of a fluid such as water, the opening method by high-frequency vibration using a liquid as a medium, or the opening method by processing by pressurization with a roll. Etc. By opening the fiber in this manner, the glass fiber fabric can be easily impregnated with the resin.
　ガラス繊維織物の織組織は平織り、綾織り、朱子織等いずれも使用できるが、平織のガラス繊維織物が好ましい。 The woven structure of the glass fiber woven fabric may be any of plain weave, twill weave, satin weave, etc., but plain woven glass fiber woven fabric is preferred.
　ガラス繊維織物は、バインダ樹脂との界面親和性を高めるために、シランカップリング剤等で表面処理されていることが好ましい。シランカップリング剤としては、ビニルトリクロロシラン、ビニルトリエトキシシラン、ビニルトリス（β－メトキシエトキシ）シラン、γ－メタクリロキシプロピルトリメトキシシラン、γ－アミノプロピルトリエトキシシラン、γ－アニリノプロピルトリメトキシシラン、Ｎ－β－アミノエチル－γ－アミノプロピルトリメトキシシラン、Ｎ－ビニルベンジル－アミノエチル－γ－アミノプロピルトリメトキシシラン（塩酸塩）、γ－グリシドキシプロピルトリメトキシシラン、β－（３，４－エポキシシクロヘキシル）エチルトリメトキシシラン、γ－メルカプトプロピルトリメトキシシラン、及びγ－クロロプロピルトリメトキシシラン等から選ばれる１種以上が挙げられる。本発明においては、前記シランカップリング剤が、Ｎ－ビニルベンジル－アミノエチル－γ－アミノプロピルトリメトキシシラン（塩酸塩）若しくはγ－アニリノプロピルトリメトキシシラン、又はこれらの混合物であることが好ましい。シランカップリング剤を用いた表面処理は、シランカップリング剤を通常約０．０１～２０質量％程度、好ましくは約０．１～５質量％程度の濃度に溶解した溶液にガラス繊維またはその織物を浸漬、必要に応じ加水分解した後、加熱して行われる。 The glass fiber fabric is preferably surface-treated with a silane coupling agent or the like in order to increase the interface affinity with the binder resin. As silane coupling agents, vinyltrichlorosilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-anilinopropyltrimethoxysilane N-β-aminoethyl-γ-aminopropyltrimethoxysilane, N-vinylbenzyl-aminoethyl-γ-aminopropyltrimethoxysilane (hydrochloride), γ-glycidoxypropyltrimethoxysilane, β- (3 , 4-epoxycyclohexyl) ethyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane and the like. In the present invention, the silane coupling agent is preferably N-vinylbenzyl-aminoethyl-γ-aminopropyltrimethoxysilane (hydrochloride), γ-anilinopropyltrimethoxysilane, or a mixture thereof. . The surface treatment using the silane coupling agent is performed by using glass fiber or a woven fabric thereof in a solution in which the silane coupling agent is usually dissolved at a concentration of about 0.01 to 20% by mass, preferably about 0.1 to 5% by mass. Is immersed and hydrolyzed as necessary, followed by heating.
　本発明において使用されるガラス繊維織物の通気度は、ＪＩＳ規格Ｐ８１１７に基づくガーレ値で１秒／１００ｃｃ未満である。 The air permeability of the glass fiber fabric used in the present invention is less than 1 second / 100 cc as a Gurley value based on JIS standard P8117.
　ガラス繊維織物の目付は通常、１０～４０ｇ／ｍ２であり、好ましくは１５～３５ｇ／ｍ２である。 The basis weight of the glass fiber fabric is usually 10 to 40 g / m 2 , preferably 15 to 35 g / m 2 .
　前記ガラス繊維織物は、市販品を利用することができる。市販品としては、ユニチカ株式会社製ガラス繊維織物品番Ｅ０１Ｚ、Ｅ０１Ｓ、Ｅ０２Ｒ、Ｅ０３Ｅ等を例示することができる。 Commercially available products can be used for the glass fiber fabric. Examples of commercially available products include glass fiber fabric product numbers E01Z, E01S, E02R, E03E and the like manufactured by Unitika Ltd.
　本発明の通気性フィルムは、前記ガラス繊維織物の表面（前面および裏面の両面）が全面的にバインダ樹脂で被覆されている。バインダ樹脂で全面的に被覆されているかどうかは、例えば、デジタルマイクロスコープ（ＳＥＭ　倍率３００倍）でその表面（前面および裏面の両面）のデジタル画像を取得することにより判定することができる。この画像において面積が１０μｍ２以上の気孔が全く観察されない場合、表面が全面的にバインダ樹脂で被覆されていると判定される。逆に、この画像において面積が１０μｍ２以上の気孔が１個以上観察された場合は、全面的にバインダ樹脂で被覆されていないと判定される。面積１０μｍ２以上の気孔が１個以上観察されると、通気性フィルムをリチウム二次電池のセパレータとして使用した場合、自己放電等の問題が生じる。 In the breathable film of the present invention, the surface (both front and back surfaces) of the glass fiber fabric is entirely covered with a binder resin. Whether or not the entire surface is covered with the binder resin can be determined, for example, by acquiring digital images of the front surface (both front and back surfaces) with a digital microscope (SEM magnification of 300 times). If no pores having an area of 10 μm 2 or more are observed in this image, it is determined that the entire surface is covered with a binder resin. Conversely, if one or more pores having an area of 10 μm 2 or more are observed in this image, it is determined that the entire surface is not covered with the binder resin. When one or more pores having an area of 10 μm 2 or more are observed, problems such as self-discharge occur when the breathable film is used as a separator for a lithium secondary battery.
　前記判定方法において、気孔とは、デジタル画像による表面の外観上、バインダ樹脂が存在しない領域のことである。一般的には、ガラス繊維織物にバインダ樹脂を含浸させても、含浸されない領域（ピンホール）が局所的に生じることがある。このようなバインダ樹脂が存在しない領域はデジタル画像上、その周辺のバインダ樹脂が存在する領域と、色、厚み等の差異に基づいて、明らかに区別できるものである。本発明の通気性フィルムにおいては、そのような気孔が１つも存在しない。 In the determination method, the pore is a region where the binder resin is not present on the surface appearance by a digital image. In general, even when a glass fiber fabric is impregnated with a binder resin, a non-impregnated region (pinhole) may be locally generated. Such a region where the binder resin is not present can be clearly distinguished from a region where the binder resin around it is present on the digital image based on differences in color, thickness, and the like. In the breathable film of the present invention, no such pores exist.
　本発明の通気性フィルムにおいては、ガラス繊維織物の表面が、全面的にバインダ樹脂で被覆されているにも拘わらす、良好な通気性を有する。これはガラス繊維織物の糸の構成繊維間に均一かつ微細な直線状の気孔が形成されているからと推定される。詳しくは、本発明の通気性フィルムにおいては、ガラス繊維織物の表面が全面的にバインダ樹脂で被覆されて、ガラス繊維織物の糸を構成する複数のガラス繊維間にバインダ樹脂が十分に充填されている。そのようなガラス繊維間でのバインダ樹脂の存在にも拘わらず、ガラス繊維間において当該ガラス繊維に対して略平行に気孔が形成されているため、良好な通気性を有するものと考えられる。 The air permeable film of the present invention has good air permeability even though the surface of the glass fiber fabric is entirely covered with the binder resin. This is presumably because uniform and fine linear pores are formed between the constituent fibers of the yarn of the glass fiber fabric. Specifically, in the breathable film of the present invention, the surface of the glass fiber fabric is entirely covered with the binder resin, and the binder resin is sufficiently filled between the plurality of glass fibers constituting the yarn of the glass fiber fabric. Yes. Despite the presence of such a binder resin between the glass fibers, pores are formed between the glass fibers substantially in parallel with the glass fibers, and therefore it is considered that the glass fibers have good air permeability.
　本発明で用いられるバインダ樹脂の種類に制限は無いが、例えば、変性ポリオレフィン、ポリフッ化ビニリデン、ポリアクリロニトリル、ポリエチレンオキサイド、ポリメチルメタクリレート、ポリイミド、ポリアミド、ポリアミドイミド等を挙げることができ、これらを混合して用いることも可能である。これらの中でも、特に、ガラス繊維織物との接着性の観点から、変性ポリオレフィン樹脂が好ましい。 The type of binder resin used in the present invention is not limited, but examples thereof include modified polyolefin, polyvinylidene fluoride, polyacrylonitrile, polyethylene oxide, polymethyl methacrylate, polyimide, polyamide, polyamideimide, and the like. It can also be used. Among these, a modified polyolefin resin is particularly preferable from the viewpoint of adhesiveness with a glass fiber fabric.
　変性ポリオレフィン系樹脂としては、ポリオレフィンに対して不飽和カルボン酸がランダム共重合またはグラフト共重合した構造を有する共重合体を用いることが好ましい。 As the modified polyolefin resin, it is preferable to use a copolymer having a structure in which an unsaturated carboxylic acid is randomly copolymerized or graft copolymerized with polyolefin.
　変性ポリオレフィン系樹脂の骨格となるポリオレフィンの具体例としては、低密度ポリエチレン、高密度ポリエチレン、ポリプロピレン、エチレン－ブテン－１共重合体、エチレン－プロピレン共重合体、ポリブタジエン等を挙げることができる。 Specific examples of the polyolefin as the skeleton of the modified polyolefin resin include low density polyethylene, high density polyethylene, polypropylene, ethylene-butene-1 copolymer, ethylene-propylene copolymer, polybutadiene and the like.
　不飽和カルボン酸は、１分子中、少なくとも１つのラジカル重合性結合（特に二重結合）と少なくとも１つのカルボキシル基を有する不飽和カルボン酸およびその無水物である。その具体例としては、アクリル酸、メタクリル酸、マレイン酸、無水マレイン酸、イタコン酸、無水イタコン酸、アコニット酸、無水アコニット酸、フマル酸、クロトン酸、シトラコン酸等を挙げることができる。変性ポリオレフィン系樹脂は不飽和カルボン酸として２種類以上の化合物を含有してもよい。ポリオレフィン樹脂への導入のし易さの点および前記シランカップリング剤で処理されたガラス繊維織物との接着性確保の点から、無水マレイン酸、アクリル酸、メタクリル酸が好ましい。 The unsaturated carboxylic acid is an unsaturated carboxylic acid having at least one radical polymerizable bond (particularly a double bond) and at least one carboxyl group in one molecule, and an anhydride thereof. Specific examples thereof include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, aconitic acid, aconitic anhydride, fumaric acid, crotonic acid, citraconic acid and the like. The modified polyolefin resin may contain two or more kinds of compounds as unsaturated carboxylic acid. Maleic anhydride, acrylic acid, and methacrylic acid are preferable from the viewpoint of easy introduction into a polyolefin resin and securing adhesion to a glass fiber fabric treated with the silane coupling agent.
　変性ポリオレフィン系樹脂は、所定のモノマーを界面重合法、溶液重合法、懸濁重合法等の公知の方法により重合させることにより製造することもできるし、または市販品として水を主分散媒とした水性エマルジョン、有機溶媒を主溶媒とした溶液等の形態で入手することもできる。変性ポリオレフィン系樹脂は、環境適合性の観点から、水性エマルジョン形態のものを用いることが好ましい。変性ポリオレフィン系樹脂の水性エマルジョンは、例えば、特許第３６９９９３５号、特許第３７５９１６０号公報等に記載された方法で製造することができる。市販品としては、ユニチカ株式会社製「アローベース」（商品名）の品番ＳＡ－１２００、ＳＢ－１２００、ＳＥ－１２００、ＳＢ－１０１０等を例示することができる。このような市販品は変性ポリオレフィン系樹脂の水性エマルジョンである。 The modified polyolefin resin can be produced by polymerizing a predetermined monomer by a known method such as an interfacial polymerization method, a solution polymerization method, a suspension polymerization method, or a commercially available product using water as a main dispersion medium. It can also be obtained in the form of an aqueous emulsion or a solution containing an organic solvent as a main solvent. The modified polyolefin resin is preferably in the form of an aqueous emulsion from the viewpoint of environmental compatibility. An aqueous emulsion of a modified polyolefin resin can be produced, for example, by a method described in Japanese Patent No. 3699935, Japanese Patent No. 3759160, and the like. Examples of commercially available products include “Arrow Base” (trade name) product numbers SA-1200, SB-1200, SE-1200, and SB-1010 manufactured by Unitika Corporation. Such a commercial product is an aqueous emulsion of a modified polyolefin resin.
　変性ポリオレフィン系樹脂としては、組成、分子量および／または融点が異なる２種以上の変性ポリオレフィン系樹脂を用いてもよい。このとき、２種以上の変性ポリオレフィン系樹脂はそれぞれが上述の範囲のものであればよい。 As the modified polyolefin resin, two or more kinds of modified polyolefin resins having different compositions, molecular weights and / or melting points may be used. At this time, each of the two or more kinds of modified polyolefin resins may be in the above-mentioned range.
　変性ポリオレフィン系樹脂中には、耐熱性を向上させるため架橋剤を配合することが好ましい。 In the modified polyolefin resin, a crosslinking agent is preferably blended in order to improve heat resistance.
　架橋剤はバインダ樹脂、特に変性ポリオレフィン系樹脂の架橋剤であり、例えば、バインダ樹脂が有するカルボキシル基や酸無水物基と反応し得る反応性基を１分子中、２個以上有する有機化合物（熱可塑性または熱硬化性の高分子を含む）である。架橋剤の具体例としては、オキサゾリン系、メラミン系、エポキシ系等の架橋剤を挙げることができ、オキサゾリン系の架橋剤が好ましい。 The cross-linking agent is a cross-linking agent for a binder resin, particularly a modified polyolefin resin. For example, an organic compound (heat) having two or more reactive groups in one molecule capable of reacting with a carboxyl group or an acid anhydride group of the binder resin. Including a plastic or thermosetting polymer). Specific examples of the crosslinking agent include oxazoline-based, melamine-based, and epoxy-based crosslinking agents, and oxazoline-based crosslinking agents are preferable.
　オキサゾリン系架橋剤は１分子中、オキサゾリン基を２個以上有する有機化合物（熱可塑性または熱硬化性の高分子を含む）である。オキサゾリン系架橋剤としては、日本触媒株式会社製のＷＳ－７００等として入手可能である。 The oxazoline-based crosslinking agent is an organic compound (including a thermoplastic or thermosetting polymer) having two or more oxazoline groups in one molecule. An oxazoline-based crosslinking agent is available as WS-700 manufactured by Nippon Shokubai Co., Ltd.
　架橋剤が配合される場合、架橋剤の配合量は、バインダ樹脂の含浸量をより一層十分に確保し、かつ糸の構成繊維間において直線状の気孔をより一層十分に形成する観点から、バインダ樹脂、特に変性ポリオレフィン系樹脂に対して３～３０質量％が好ましく、より好ましくは５～２０質量％である。２種類以上の架橋剤を使用する場合、それらの合計配合量が前記配合量の範囲内であればよい。 When a cross-linking agent is blended, the amount of the cross-linking agent is selected from the viewpoint of ensuring a sufficiently sufficient amount of the binder resin to be impregnated and forming linear pores more sufficiently between the constituent fibers of the yarn. The content is preferably 3 to 30% by mass, more preferably 5 to 20% by mass, based on the resin, particularly the modified polyolefin resin. When using 2 or more types of crosslinking agents, the total compounding quantity should just be in the range of the said compounding quantity.
　本発明の通気性フィルムにおいて、バインダ樹脂の含浸量は、ガラス繊維織物に対して５～４０質量％が好ましく、より好ましくは１０～３０質量％である。バインダ樹脂に架橋剤が配合される場合、バインダ樹脂および架橋剤の合計含浸量がバインダ樹脂の含浸量である。 In the breathable film of the present invention, the impregnation amount of the binder resin is preferably 5 to 40% by mass, more preferably 10 to 30% by mass with respect to the glass fiber fabric. When a crosslinking agent is blended in the binder resin, the total impregnation amount of the binder resin and the crosslinking agent is the impregnation amount of the binder resin.
　本発明の通気性フィルムは通気度が、ガーレ値（ＪＩＳ規格Ｐ８１１７）で１０００秒／１００ｃｃ以下１秒／１００ｃｃ以上であり、好ましい通気度は、６００秒／１００ｃｃ以下１００秒／１００ｃｃ以上である。本発明においては、このような通気度を有するという意味で「通気性」との表現を用いている。通気度を前記のようにすることにより、リチウム二次電池用セパレータとして用いた場合、良好なイオン透過性を確保することができる。本発明において前記通気度はバインダ樹脂の含浸量を調整することにより制御することができる。バインダ樹脂の含浸量が多いほど、前記通気度は増加する。 The air permeable film of the present invention has a Gurley value (JIS standard P8117) of 1000 seconds / 100 cc or less and 1 second / 100 cc or more, and a preferable air permeability is 600 seconds / 100 cc or less and 100 seconds / 100 cc or more. In the present invention, the expression “breathability” is used in the sense of having such air permeability. By using the air permeability as described above, good ion permeability can be secured when used as a separator for a lithium secondary battery. In the present invention, the air permeability can be controlled by adjusting the amount of the binder resin impregnated. The air permeability increases as the amount of the binder resin impregnated increases.
　本発明の通気性フィルムは通気斑が、通気性フィルムの任意の箇所１０点のガーレ値（ＪＩＳ規格Ｐ８１１７）の平均値に対し±２５％以下であることが好ましく、±２０％以下であることがさらに好ましい。このようにすることにより、均一な通気性が確保される。本発明において前記通気斑は基材としてガラス繊維織物を用いること、および後述の再開繊処理を行うことにより確保される。 In the breathable film of the present invention, the breathing spots are preferably ± 25% or less, more preferably ± 20% or less with respect to the average value of the Gurley values (JIS standard P8117) at 10 points in the breathable film. Is more preferable. By doing so, uniform air permeability is ensured. In the present invention, the air spots are secured by using a glass fiber fabric as a base material and performing a re-fibering process described later.
　本発明の通気性フィルムの耐熱性としては、１５０℃処理での形状維持率が９８％以上であることが好ましく、９９％以上であることがより好ましい。ここで、１５０℃での形状維持率は、通気性フィルムを、８ｃｍ×８ｃｍに切り出し、その中に６ｃｍ×６ｃｍの四角を書き入れた通気性フィルムを、１５０℃のオーブンに３０分入れて加熱し、加熱後のフィルムの線間隔を測定することにより算出することができる。このようにすることにより、例えば、耐熱性を有するリチウム２次電池用セパレータとして好適に用いることができる。本発明において前記耐熱性は基材としてガラス繊維織物を用いることにより確保される。 As the heat resistance of the breathable film of the present invention, the shape retention rate at 150 ° C. is preferably 98% or more, and more preferably 99% or more. Here, the shape retention rate at 150 ° C. was determined by cutting the breathable film into 8 cm × 8 cm, and writing a 6 cm × 6 cm square in the breathable film in a 150 ° C. oven for 30 minutes and heating. It can be calculated by measuring the line spacing of the heated film. By doing in this way, it can use suitably as a separator for lithium secondary batteries which has heat resistance, for example. In the present invention, the heat resistance is ensured by using a glass fiber fabric as a substrate.
［通気性フィルムの製造方法］
　本発明の通気性フィルムは、例えば、以下の３工程により容易に得ることができる。 [Method for producing breathable film]
The breathable film of the present invention can be easily obtained by the following three steps, for example.
＜第１工程＞
　前記バインダ樹脂を溶液もしくはエマルジョンとし、前記ガラス繊維織物に含浸するための含浸液（以下、単に「含浸液」と略記することがある）を調製する。この含浸液には、前記した架橋剤、ポリオレフィン系樹脂粒子等の有機高分子の微粒子、およびアルミナ等の無機酸化物からなる微粒子等が配合されていてもよい。また、エマルジョン安定剤、各種界面活性剤等が配合されていてもよい。 <First step>
The binder resin is made into a solution or an emulsion, and an impregnating liquid for impregnating the glass fiber fabric (hereinafter sometimes simply referred to as “impregnating liquid”) is prepared. The impregnating liquid may contain the above-mentioned crosslinking agent, organic polymer fine particles such as polyolefin resin particles, and fine particles composed of an inorganic oxide such as alumina. Moreover, an emulsion stabilizer, various surfactants, etc. may be mix | blended.
　含浸液のバインダ樹脂濃度は特に制限されない。例えば、バインダ樹脂濃度が薄すぎて、バインダ樹脂の所望の含浸量が達成されない場合には、第２工程における含浸または塗布および乾燥を繰り返せばよい。 The binder resin concentration of the impregnating liquid is not particularly limited. For example, when the binder resin concentration is too thin to achieve the desired amount of impregnation of the binder resin, the impregnation or application and drying in the second step may be repeated.
＜第２工程＞
　前記含浸液を前記ガラス繊維織物に含浸または塗布した後、乾燥して溶媒もしくは分散媒を除去する。ここで含浸または塗布により、ガラス繊維織物の空隙部分に含浸液が充填される。具体的な方法としては、たとえばガラス繊維織物を前記溶液もしくはエマルジョンの中に浸漬した後に引き上げてマングル等を使用して絞液するディップ塗布方法、ダイや塗工ロールにより溶液もしくはエマルジョンを支持体に転写する転写式塗布方法といった公知の塗布方法が好適に用いられる。この際、前記溶液もしくはエマルジョンをガラス繊維織物の表裏表面へ同時に塗布してもよい。 <Second step>
The glass fiber fabric is impregnated or coated with the impregnation liquid, and then dried to remove the solvent or dispersion medium. Here, the impregnating liquid is filled in the voids of the glass fiber fabric by impregnation or coating. Specific methods include, for example, a dip coating method in which a glass fiber fabric is dipped in the solution or emulsion and then pulled up and squeezed using a mangle or the like, or the solution or emulsion is applied to a support by a die or a coating roll. A known coating method such as a transfer type coating method for transferring is suitably used. At this time, the solution or emulsion may be simultaneously applied to the front and back surfaces of the glass fiber fabric.
　含浸後、溶媒もしくは分散媒を除去するための乾燥温度としては、５０～１５０℃とすることが好ましい。このように設定することにより、ガラス繊維織物とバインダ樹脂の良好な接着性を確保することができる。乾燥の際、バインダ樹脂含浸後のガラス繊維織物の通気性を一旦消失させることが好ましい。このようにするには、前記ガラス繊維織物に前記バインダ樹脂を含浸する際、バインダ樹脂の含浸量を、ガラス繊維織物に対し、１５～３５質量％、好ましくは、２０～３０質量％とすればよい。これにより、ガラス繊維織物の表面をバインダ樹脂が全面的に被覆され、通気性を消失させることができる。ここで、「通気性が消失する」とはガーレ値が２０００秒／１００ｃｃ超となっているかどうかで判断される。すなわち、ガーレ値が２０００秒／１００ｃｃ超であるとき、通気性が消失していると判断され、ピンホール等が無い状態で表面がバインダ樹脂で全面的に被覆されていることが確認できる。本工程でのバインダ樹脂の含浸量が少なすぎると、最終的に得られる通気性フィルムの表面が十分にバインダ樹脂で被覆されないので、当該通気性フィルムをリチウム二次電池のセパレータとして使用した場合、自己放電等の問題が生じる。本工程でのバインダ樹脂の含浸量が多すぎると、後述の再開繊処理を行っても、通気性フィルムの通気度は十分に低下しないので、リチウム二次電池のセパレータとしての使用に耐えない。バインダ樹脂に架橋剤が配合される場合、バインダ樹脂および架橋剤の合計含浸量がバインダ樹脂の含浸量である。 After the impregnation, the drying temperature for removing the solvent or the dispersion medium is preferably 50 to 150 ° C. By setting in this way, it is possible to ensure good adhesion between the glass fiber fabric and the binder resin. In drying, it is preferable that the air permeability of the glass fiber fabric after impregnation with the binder resin is once lost. For this purpose, when the glass fiber fabric is impregnated with the binder resin, the amount of the binder resin impregnated is 15 to 35% by mass, preferably 20 to 30% by mass with respect to the glass fiber fabric. Good. Thereby, the surface of the glass fiber fabric is entirely covered with the binder resin, and the air permeability can be lost. Here, “loss of air permeability” is determined by whether or not the Gurley value is more than 2000 seconds / 100 cc. That is, when the Gurley value is more than 2000 seconds / 100 cc, it is determined that the air permeability is lost, and it can be confirmed that the surface is entirely covered with the binder resin without any pinholes or the like. If the impregnation amount of the binder resin in this step is too small, the surface of the finally obtained breathable film is not sufficiently covered with the binder resin, so when the breathable film is used as a separator for a lithium secondary battery, Problems such as self-discharge occur. If the amount of the binder resin impregnated in this step is too large, the air permeability of the air permeable film will not be sufficiently lowered even if the re-opening fiber treatment described later is performed, so that it cannot be used as a separator for a lithium secondary battery. When a crosslinking agent is blended in the binder resin, the total impregnation amount of the binder resin and the crosslinking agent is the impregnation amount of the binder resin.
＜第３工程＞
　通気性が消失したバインダ樹脂含浸ガラス繊維織物を再開繊処理する。バインダ樹脂含浸ガラス繊維織物においては、糸の構成繊維間にバインダ樹脂が含浸され、複数の構成繊維が一体化されている。再開繊処理とは、そのような一体化繊維を少なくとも部分的にほぐして、構成繊維間において当該繊維に対して略平行に気孔を形成する処理である。このようにすることにより、ガラス繊維織物の糸の構成繊維間に均一な直線状の気孔が形成されて通気性が回復し、バインダ樹脂含浸ガラス繊維織物の均一な通気性が確保できる。 <Third step>
The binder resin-impregnated glass fiber fabric whose air permeability has been lost is subjected to a re-fiber treatment. In a binder resin-impregnated glass fiber fabric, a binder resin is impregnated between yarn constituent fibers, and a plurality of constituent fibers are integrated. The restart fiber process is a process in which such integrated fibers are at least partially loosened to form pores substantially parallel to the fibers between the constituent fibers. By doing so, uniform linear pores are formed between the constituent fibers of the yarn of the glass fiber fabric, and the air permeability is restored, and the uniform air permeability of the binder resin-impregnated glass fiber fabric can be ensured.
　再開繊処理の方法としては、バインダ樹脂含浸ガラス繊維織物に対して振動を付与することにより、構成繊維間において直線状の気孔が形成される限り特に制限されない。中でも、水中で振動を付与する振動処理が好ましく、例えば、水中で、凹凸のあるローターを回転させて振動を付与する振動処理装置を用いることが好ましい。このような振動処理装置として、株式会社小松原製ＦＶ洗浄機を例示することができる。 The method for resuming the fiber is not particularly limited as long as linear pores are formed between the constituent fibers by applying vibration to the binder resin-impregnated glass fiber fabric. Among them, vibration treatment that imparts vibration in water is preferable. For example, it is preferable to use a vibration treatment device that imparts vibration by rotating a rotor having unevenness in water. As such a vibration processing apparatus, an FV washing machine manufactured by Komatsubara Co., Ltd. can be exemplified.
　付与される振動の強さは、構成繊維間において直線状の気孔が形成される限り特に制限されない。例えば、水中で付与される振動の強さは、凹凸のあるローターの回転により振動を付与する場合、当該回転数で４００～１０００ｒｐｍが好適である。 The strength of the vibration applied is not particularly limited as long as linear pores are formed between the constituent fibers. For example, the strength of vibration applied in water is preferably 400 to 1000 rpm when the vibration is applied by rotation of an uneven rotor.
　再開繊処理の処理温度および処理時間は、前記した所定の通気度が得られる限り特に限定されない。
　水の温度等の処理温度は、通常、１０～８０℃である。本発明において通気性フィルムの通気度は当該処理温度を調整することにより制御することができる。処理温度が高いほど、通気性フィルムの通気度は減少する。
　振動付与時間等の処理時間は、通常、０．５～１０分間である。本発明において通気性フィルムの通気度は当該処理時間を調整することにより制御することができる。処理時間が長いほど、通気性フィルムの通気度は減少する。 The treatment temperature and treatment time of the resuming fiber treatment are not particularly limited as long as the predetermined air permeability described above can be obtained.
The treatment temperature such as the temperature of water is usually 10 to 80 ° C. In the present invention, the air permeability of the air permeable film can be controlled by adjusting the treatment temperature. The higher the processing temperature, the lower the air permeability of the breathable film.
The processing time such as vibration applying time is usually 0.5 to 10 minutes. In the present invention, the air permeability of the air permeable film can be controlled by adjusting the treatment time. The longer the treatment time, the lower the air permeability of the breathable film.
　以上述べたように、本発明の通気性フィルムを構成するガラス繊維織物は、高温での形状安定性が極めて良好で、連続した長繊維からなり、剛性が高い。本発明においては、このようなガラス繊維織物は通常、開繊処理して製造され、当該ガラス繊維織物にバインダ樹脂を含浸して通気性を一旦消失させる（第２工程）。その後、再開繊処理を行う（第３工程）。このため、本発明の通気性フィルムは、ピンホール等が無く、均一な通気性を有し、かつ高い力学的特性と耐熱性を有するものである。従って、本発明の通気性フィルムは、例えば、リチウム二次電池用セパレータ、キャパシタ用セパレータ、電子基板、チップパッケージおよび回路ボード等の電子デバイス用基板材料、ならびに液体および気体のフィルタ等として好適に使用することができる。 As described above, the glass fiber fabric constituting the breathable film of the present invention has very good shape stability at high temperature, is composed of continuous long fibers, and has high rigidity. In the present invention, such a glass fiber woven fabric is usually produced by a fiber opening treatment, and the glass fiber woven fabric is impregnated with a binder resin to temporarily lose air permeability (second step). Thereafter, resuming fiber processing is performed (third step). For this reason, the breathable film of the present invention has no pinholes, has uniform breathability, and has high mechanical properties and heat resistance. Therefore, the breathable film of the present invention is suitably used as, for example, a lithium secondary battery separator, a capacitor separator, a substrate material for electronic devices such as an electronic substrate, a chip package and a circuit board, and a liquid and gas filter. can do.
　以下に実施例を挙げて、本発明をさらに具体的に説明する。なお本発明は実施例により限定されるものではない。 The present invention will be described more specifically with reference to the following examples. The present invention is not limited to the examples.
　実施例及び比較例において通気性フィルムの特性等は以下の方法で評価した。 In the examples and comparative examples, the properties of the breathable film were evaluated by the following methods.
（１）厚み（単位：μｍ）
　通気性フィルムの厚みは、ＪＩＳ　Ｋ７１３０－１９９２に基づいて測定した。 (1) Thickness (unit: μm)
The thickness of the breathable film was measured based on JIS K7130-1992.
（２）通気度（単位：秒／１００ｃｃ）
　通気性フィルムの通気度（ガーレ値）は、ＪＩＳ　Ｐ８１１７に基づいて測定した。 (2) Air permeability (unit: seconds / 100cc)
The air permeability (Gurley value) of the air permeable film was measured based on JIS P8117.
（３）通気斑
　通気性フィルムの任意の箇所１０点の通気度を測定し、その平均値からの乖離率を算出し、その最大値もしくは最小値を変動率とした。変動率が±２０％以下の場合を均一性が良好、±２０％超の場合を均一性が不良と判定した。 (3) Ventilation spots The air permeability at 10 points in the breathable film was measured, the deviation rate from the average value was calculated, and the maximum value or the minimum value was taken as the variation rate. When the variation rate was ± 20% or less, the uniformity was judged to be good, and when it was more than ± 20%, the uniformity was judged to be poor.
（４）バインダ樹脂による表面被覆状態
　キーエンス社製のＶＨＸ－１０００（光学レンズ内臓）にＶＨＸ－Ｄ５１０（電子レンズ内蔵）が組み込まれたデジタルマイクロスコープを用い、通気性フィルムの表面（前面および裏面）の任意の箇所１０点を観察し、倍率３００倍のデジタル画像を取得し、面積が１０μｍ２以上の気孔の観察されない場合、表面が全面的にバインダ樹脂で被覆されていると判定した。逆に、この画像において面積が１０μｍ２以上の気孔が１個以上観察された場合は、全面的にバインダ樹脂で被覆されていないと判定した。 (4) Surface coating with binder resin Using a digital microscope in which VHX-D510 (built-in electronic lens) is incorporated into VHX-1000 (built-in optical lens) manufactured by Keyence Corporation, the surface of the breathable film (front and back) 10 points were observed, a digital image with a magnification of 300 times was obtained, and when pores having an area of 10 μm 2 or more were not observed, it was determined that the entire surface was covered with a binder resin. Conversely, when one or more pores having an area of 10 μm 2 or more were observed in this image, it was determined that the entire surface was not covered with the binder resin.
（５）耐熱性
　通気性フィルムを、８ｃｍ×８ｃｍに切り出し、その中に６ｃｍ×６ｃｍの四角を書き入れた通気性フィルムを、１５０℃のオーブンに入れて３０分加熱した。加熱後のフィルムの線間隔を測定することで、加熱形状維持率を算出することにより評価し、この値が９８％以上である場合、耐熱性が良好であると判定した。 (5) Heat resistance The breathable film was cut into 8 cm x 8 cm, and the breathable film in which a 6 cm x 6 cm square was written therein was placed in an oven at 150 ° C and heated for 30 minutes. By measuring the line spacing of the heated film, it was evaluated by calculating the heating shape retention rate. When this value was 98% or more, it was determined that the heat resistance was good.
〔実施例１〕
　第１工程：
　平織のガラス繊維織物（目付け２４ｇ／ｍ２、厚み２０μｍ、ガラス繊維径φ４．１μｍ×１００本束、通気度１秒／１００ｃｃ未満、開繊処理およびシランカップリング処理済）を用意した。ガラス繊維織物表面の顕微鏡写真を図１に示す。一方、含浸用の変性ポリオレフィン系樹脂として、変性ポリオレフィン系樹脂の水性エマルジョンであるユニチカ株式会社製「アローベース」（商品名）の品番ＳＢ－１２００を用意した。この水性エマルジョンに、オキサゾリン系架橋剤（日本触媒株式会社製ＷＳ－７００）を加えて撹拌し、均一な分散体として、含浸液を調製した。ここで、オキサゾリン系架橋剤の配合量は、変性ポリオレフィン系樹脂（固形分）に対し、５．９質量％とした。 [Example 1]
First step:
A plain-woven glass fiber fabric (weighing 24 g / m 2 , thickness 20 μm, glass fiber diameter φ4.1 μm × 100 bundle, air permeability less than 1 second / 100 cc, fiber opening treatment and silane coupling treatment) was prepared. A photomicrograph of the glass fiber fabric surface is shown in FIG. On the other hand, as the modified polyolefin resin for impregnation, “Arrobase” (trade name) product number SB-1200, which is an aqueous emulsion of a modified polyolefin resin, was prepared. To this aqueous emulsion, an oxazoline-based crosslinking agent (WS-700 manufactured by Nippon Shokubai Co., Ltd.) was added and stirred to prepare an impregnating solution as a uniform dispersion. Here, the blending amount of the oxazoline-based crosslinking agent was 5.9% by mass with respect to the modified polyolefin-based resin (solid content).
　第２工程：
　前記ガラス繊維織物を、適度に希釈した前記含浸液に浸漬処理し、マングルで絞液し、次いで、８０℃で９０秒乾燥して、ガラス繊維織物に対して２０．０質量％のバインダ樹脂が含浸されたガラス繊維織物を得た。このガラス繊維織物の通気度は２０００秒／１００ｃｃ超であり、通気性が消失していることが確認された。また、表面被覆状態を観察したところ、全面がバインダ樹脂で被覆されていた。バインダ樹脂含浸ガラス繊維織物表面の顕微鏡写真を図２に示す。 Second step:
The glass fiber fabric is dipped in the appropriately diluted impregnation solution, squeezed with a mangle, and then dried at 80 ° C. for 90 seconds to obtain 20.0% by mass of a binder resin based on the glass fiber fabric. An impregnated glass fiber fabric was obtained. The air permeability of this glass fiber fabric was over 2000 seconds / 100 cc, and it was confirmed that the air permeability was lost. Moreover, when the surface coating state was observed, the whole surface was coat | covered with binder resin. A photomicrograph of the surface of the binder resin-impregnated glass fiber fabric is shown in FIG.
　第３工程：
　次に、前記バインダ樹脂含浸ガラス繊維織物に対して、株式会社小松原製ＦＶ洗浄機を用いて、７０℃の水中にて１分間、振動を付与して、再開繊処理を行った。ここでＦＶ洗浄機の回転数としては７００ｒｐｍとした。得られた通気性フィルムの通気度は３１０秒／１００ｃｃ、通気斑は１５．２％であり、良好かつ均一な通気性が確認された。また、この通気性フィルムの加熱形状維持率は、９９．１％と良好であった。最終的に得られた通気性フィルムにおけるバインダ樹脂および架橋剤の合計含浸量は、ガラス繊維織物に対して２０質量％であった。通気性フィルムの表面被覆状態を観察したところ、全面がバインダ樹脂で被覆されていた。通気性フィルム表面の顕微鏡写真を図３に示す。 Third step:
Next, with respect to the binder resin-impregnated glass fiber woven fabric, using a FV washer manufactured by Komatsubara Co., Ltd., vibration was applied for 1 minute in water at 70 ° C. to perform a re-fiber treatment. Here, the rotation speed of the FV washer was 700 rpm. The obtained air permeable film had an air permeability of 310 seconds / 100 cc and air spots of 15.2%, confirming good and uniform air permeability. Moreover, the heating shape maintenance rate of this air permeable film was as favorable as 99.1%. The total impregnation amount of the binder resin and the crosslinking agent in the finally obtained breathable film was 20% by mass with respect to the glass fiber fabric. When the surface covering state of the breathable film was observed, the entire surface was covered with a binder resin. A photomicrograph of the surface of the breathable film is shown in FIG.
〔実施例２〕
　第２工程においてバインダ樹脂の含浸量を１７質量％としたこと以外は実施例１と同様に行い、通気性フィルムを得た。第２工程において得られたガラス繊維織物の通気度は２０００秒／１００ｃｃ超であり、通気性が消失していることが確認された。第３工程で得られた通気性フィルムの通気度は２５６秒／１００ｃｃ、通気斑は１７．５％であり、良好かつ均一な通気性が確認された。また、この通気性フィルムの加熱形状維持率は、９８．８％と良好であった。最終的に得られた通気性フィルムにおけるバインダ樹脂および架橋剤の合計含浸量は、ガラス繊維織物に対して１７質量％であった。通気性フィルムの表面被覆状態を観察したところ、全面がバインダ樹脂で被覆されていた。 [Example 2]
A breathable film was obtained in the same manner as in Example 1 except that the amount of the binder resin impregnated in the second step was 17% by mass. The air permeability of the glass fiber fabric obtained in the second step was over 2000 seconds / 100 cc, and it was confirmed that the air permeability was lost. The air permeable film obtained in the third step had an air permeability of 256 sec / 100 cc and air spots of 17.5%, confirming good and uniform air permeability. Moreover, the heating shape maintenance factor of this air permeable film was as good as 98.8%. The total impregnation amount of the binder resin and the crosslinking agent in the finally obtained breathable film was 17% by mass with respect to the glass fiber fabric. When the surface covering state of the breathable film was observed, the entire surface was covered with a binder resin.
〔実施例３〕
　第２工程においてバインダ樹脂の含浸量を２３質量％としたこと以外は実施例１と同様に行い、通気性フィルムを得た。第２工程において得られたガラス繊維織物の通気度は２０００秒／１００ｃｃ超であり、通気性が消失していることが確認された。第３工程で得られた通気性フィルムの通気度は５２８秒／１００ｃｃ、通気斑は１４．３％であり、良好かつ均一な通気性が確認された。また、この通気性フィルムの加熱形状維持率は、９９．３％と良好であった。最終的に得られた通気性フィルムにおけるバインダ樹脂および架橋剤の合計含浸量は、ガラス繊維織物に対して２３質量％であった。通気性フィルムの表面被覆状態を観察したところ、全面がバインダ樹脂で被覆されていた。 Example 3
A breathable film was obtained in the same manner as in Example 1 except that the binder resin impregnation amount was 23% by mass in the second step. The air permeability of the glass fiber fabric obtained in the second step was over 2000 seconds / 100 cc, and it was confirmed that the air permeability was lost. The air permeable film obtained in the third step had an air permeability of 528 sec / 100 cc and air spots of 14.3%, confirming good and uniform air permeability. Moreover, the heating shape maintenance factor of this air permeable film was as favorable as 99.3%. The total impregnation amount of the binder resin and the crosslinking agent in the finally obtained breathable film was 23% by mass with respect to the glass fiber fabric. When the surface covering state of the breathable film was observed, the entire surface was covered with a binder resin.
〔比較例１〕
　第２工程においてバインダ樹脂の含浸量を１０質量％としたこと以外は実施例１と同様にバインダ樹脂の含浸処理行った。再開繊処理前の通気度は１５６秒／１００ｃｃであり、通気性は消失していなかった。このバインダ樹脂含浸ガラス繊維織物の表面被覆状態を観察したころ、面積が１０μｍ２以上の気孔が２個観察され、表面は全面的にバインダ樹脂で被覆されていないと判定された。このバインダ樹脂含浸ガラス繊維織物の表面の顕微鏡写真を図４に示す。また、このバインダ樹脂含浸ガラス繊維織物の通気斑は３５．２％となり、均一な通気性は有していなかった。 [Comparative Example 1]
In the second step, the binder resin was impregnated in the same manner as in Example 1 except that the amount of the binder resin impregnated was 10% by mass. The air permeability before the reopening fiber treatment was 156 seconds / 100 cc, and the air permeability was not lost. When the surface covering state of the binder resin-impregnated glass fiber fabric was observed, two pores having an area of 10 μm 2 or more were observed, and it was determined that the surface was not entirely covered with the binder resin. A photomicrograph of the surface of this binder resin-impregnated glass fiber fabric is shown in FIG. Further, the air bubble unevenness of the binder resin-impregnated glass fiber fabric was 35.2%, and the air permeability was not uniform.
〔比較例２〕
　第２工程においてバインダ樹脂の含浸量を４０質量％としたこと以外は実施例１と同様にバインダ樹脂の含浸処理行った。再開繊処理前の表面被覆状態を観察したところ、全面がバインダ樹脂で被覆されていた。再開繊処理前の通気度は２０００秒／１００ｃｃ超であり、通気性は消失していた。
　このバインダ樹脂含浸ガラス繊維織物を実施例１と同様にして、再開繊処理を行った。再開繊処理後の通気度は２０００秒／１００ｃｃ超であり、通気性は有していなかった。最終的に得られた通気性フィルムにおけるバインダ樹脂および架橋剤の合計含浸量は、ガラス繊維織物に対して４０質量％であった。通気性フィルムの表面被覆状態を観察したところ、全面がバインダ樹脂で被覆されていた。 [Comparative Example 2]
In the second step, the binder resin was impregnated in the same manner as in Example 1 except that the amount of the binder resin impregnated was 40% by mass. When the surface covering state before resuming fiber treatment was observed, the entire surface was coated with a binder resin. The air permeability before resuming fiber treatment was over 2000 seconds / 100 cc, and the air permeability was lost.
This binder resin-impregnated glass fiber fabric was subjected to a reopening fiber treatment in the same manner as in Example 1. The air permeability after the resumption fiber treatment was more than 2000 seconds / 100 cc, and it did not have air permeability. The total impregnation amount of the binder resin and the crosslinking agent in the finally obtained breathable film was 40% by mass with respect to the glass fiber fabric. When the surface covering state of the breathable film was observed, the entire surface was covered with a binder resin.
　実施例１～３で示した様に、本発明の通気性フィルムは、通気性に優れる上、１５０℃加熱時の形状維持率が９８％以上であり、かつガーレ値変動率が±２５％以下、特に±２０％以下である。このため、本発明の通気性フィルムは耐熱性（耐熱変形性）と均一な通気性が要求されるリチウム二次電池およびキャパシタのセパレータ、電子基板、チップパッケージおよび回路ボード等の電子デバイス用基板材料、ならびに液体および気体のフィルタ等としてとして好適に使用することができる。 As shown in Examples 1 to 3, the breathable film of the present invention is excellent in breathability, has a shape retention rate of 98% or more when heated at 150 ° C., and has a Gurley value fluctuation rate of ± 25% or less. In particular, it is ± 20% or less. Therefore, the breathable film of the present invention is a substrate material for electronic devices such as lithium secondary batteries and capacitor separators, electronic substrates, chip packages and circuit boards that require heat resistance (heat deformation resistance) and uniform breathability. And as a liquid and gas filter and the like.
　本発明の通気性フィルムは、リチウム二次電池およびキャパシタのセパレータ、電子基板、チップパッケージおよび回路ボード等の電子デバイス用基板材料、ならびに液体および気体のフィルタ等として有用である。 The air-permeable film of the present invention is useful as a substrate material for electronic devices such as lithium secondary batteries and capacitor separators, electronic substrates, chip packages and circuit boards, and liquid and gas filters.

Claims (6)

  1. 　ガラス繊維織物にバインダ樹脂が含浸された通気性フィルムであって、以下の特徴を有する通気性フィルム：
    １）前記ガラス繊維織物の表面がバインダ樹脂で全面的に被覆されている；
    ２）前記通気性フィルムの通気度が、ガーレ値（ＪＩＳ規格Ｐ８１１７）で１０００秒／１００ｃｃ以下１秒／１００ｃｃ以上である。     A breathable film in which a glass fiber fabric is impregnated with a binder resin and has the following characteristics:
    1) The surface of the glass fiber fabric is entirely covered with a binder resin;
    2) The air permeability of the air permeable film is 1000 seconds / 100 cc or less and 1 second / 100 cc or more in terms of Gurley value (JIS standard P8117).
  2. 　通気度の変動率で±２５％以下の通気斑を有する請求項１に記載の通気性フィルム。 The breathable film according to claim 1, wherein the breathable film has a variation in air permeability of ± 25% or less.
  3. 　バインダ樹脂が変性ポリオレフィン系樹脂である請求項１または２に記載の通気性フィルム。 The breathable film according to claim 1 or 2, wherein the binder resin is a modified polyolefin resin.
  4. 　変性ポリオレフィン系樹脂中に架橋剤が配合されている請求項３に記載の通気性フィルム。 The air permeable film according to claim 3, wherein a crosslinking agent is blended in the modified polyolefin resin.
  5. 　開繊処理されたガラス繊維織物にバインダ樹脂を含浸して、ガラス繊維織物の通気性を一旦消失させた後、再開繊処理することを特徴とする請求項１～４に記載の通気性フィルムの製造方法。 The breathable film according to any one of claims 1 to 4, wherein the glass fiber woven fabric subjected to the fiber opening treatment is impregnated with a binder resin so that the breathability of the glass fiber woven fabric is once lost and then reopened. Production method.
  6. 　再開繊処理が水中での振動処理である請求項５に記載の通気性フィルムの製造方法。 The method for producing a breathable film according to claim 5, wherein the resuming fiber treatment is a vibration treatment in water.
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