WO2021230037A1 - Separator for secondary batteries - Google Patents

Separator for secondary batteries Download PDF

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Publication number
WO2021230037A1
WO2021230037A1 PCT/JP2021/016393 JP2021016393W WO2021230037A1 WO 2021230037 A1 WO2021230037 A1 WO 2021230037A1 JP 2021016393 W JP2021016393 W JP 2021016393W WO 2021230037 A1 WO2021230037 A1 WO 2021230037A1
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WO
WIPO (PCT)
Prior art keywords
separator
secondary battery
binder
battery according
heat
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PCT/JP2021/016393
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French (fr)
Japanese (ja)
Inventor
明人 山元
洋 大和
Original Assignee
株式会社ダイセル
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Publication of WO2021230037A1 publication Critical patent/WO2021230037A1/en

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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409Separators, membranes or diaphragms characterised by the material
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409Separators, membranes or diaphragms characterised by the material
    • H01M50/411Organic material
    • H01M50/414Synthetic resins, e.g. thermoplastics or thermosetting resins
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409Separators, membranes or diaphragms characterised by the material
    • H01M50/44Fibrous material
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409Separators, membranes or diaphragms characterised by the material
    • H01M50/449Separators, membranes or diaphragms characterised by the material having a layered structure
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries

Definitions

  • the present disclosure relates to a separator for a secondary battery, a method for manufacturing a separator for a secondary battery, and a secondary battery provided with a separator for a secondary battery.
  • a separator that insulates a positive electrode and a negative electrode while holding an electrolytic solution is used. Therefore, the separator is required to ensure electrical insulation. In addition, since the battery functions when lithium ions move through this separator, it is also required to ensure transparency.
  • the lithium-ion secondary battery has a "shutdown function" that stops the flow of lithium ions between the electrodes and safely stops the function of the battery when the inside of the battery becomes abnormally high temperature. Desired. Further, when the temperature inside the battery rises further even after the flow of lithium ions is stopped, if the separator shrinks (shrinks) or melts (melts down), the electrodes may be short-circuited or thermal runaway may occur. Therefore, the separator is required to have heat resistance that can maintain its shape even in an abnormally high temperature environment.
  • lithium-ion secondary batteries have been considered to be installed in hybrid vehicles and electric vehicles in addition to information-related equipment such as smartphones and laptop computers due to their characteristics of light weight, high voltage, and large capacity.
  • High heat resistant separators are required to cope with high energy density.
  • Patent Document 1 describes that a separator for a secondary battery containing a porous base material and a heat-resistant layer made of a non-woven fabric containing specific fine fibers and a binder has excellent heat resistance.
  • a heat-resistant layer (B) made of a non-woven fabric containing fine fibers having a melting point or decomposition temperature of 200 ° C. or higher and a binder into a porous substrate layer. It has been found that the specific structure obtained by laminating on the surface of (A) has excellent permeability, and that such a structure can be efficiently produced by a specific method. This disclosure has been completed based on these findings.
  • the present disclosure includes a porous base material layer (A) and a heat-resistant layer (B) made of a non-woven fabric containing microfibers having a melting point or a decomposition temperature of 200 ° C. or higher and a binder, and the following formula (a). , (B) are satisfied, and a separator for a secondary battery is provided.
  • (YX) / Z ⁇ 12 (a) (YX) ⁇ 60
  • X Air permeability of the porous substrate (A) (sec / 100 mL)
  • Y Air permeability of separator (sec / 100mL)
  • Z Thickness ( ⁇ m) of heat-resistant layer (B)
  • the present disclosure also provides a separator for a secondary battery in which the microfibers are aramid fibers.
  • the present disclosure also provides a separator for a secondary battery in which the above binder is a water-based binder.
  • the binder is also selected from a polysaccharide derivative (1), a compound having a structural unit represented by the following formula (2), and a compound having a structural unit represented by the following formula (3).
  • a separator for a secondary battery which is at least one kind.
  • R represents a hydroxyl group, a carboxyl group, a phenyl group, an N-substituted or unsubstituted carbamoyl group, or a 2-oxo-1-pyrrolidinyl group.
  • n represents an integer of 2 or more
  • L represents an ether bond or a (-NH-) group.
  • the present disclosure also provides a separator for a secondary battery in which the binder is at least one selected from cellulose, starch, glycogen, and derivatives thereof.
  • the present disclosure also provides a separator for a secondary battery having an average thickness of 0.01 to 10 ⁇ m and an average length of 0.01 to 2 mm of the fine fibers.
  • the present disclosure also provides a separator for a secondary battery in which the thickness of the heat-resistant layer (B) is 0.5 to 20 ⁇ m and the total thickness of the separator for the secondary battery is 10 to 50 ⁇ m.
  • the present disclosure also provides a separator for a secondary battery in which the basis weight of the heat-resistant layer (B) is 10 g / m 2 or less.
  • a release film is attached to one surface of the porous substrate layer (A), and a dispersion containing fine fibers and a binder is contained on the other surface of the porous substrate layer (A).
  • a dispersion containing fine fibers and a binder is contained on the other surface of the porous substrate layer (A).
  • the surface of the porous base material layer (A) is prepared to a Dine value of 40 to 45 mN / m by surface treatment, and a dispersion liquid containing fine fibers and a binder is applied to the surface, and the dispersion liquid is applied.
  • a method for manufacturing a separator for a secondary battery which obtains a separator for a secondary battery by volatilizing the dispersion medium inside.
  • a dispersion liquid containing microfibers and a binder is applied to one surface of the porous substrate layer (A), and low polarity or low polarity or from the other surface of the porous substrate layer (A).
  • a method for producing a separator for a secondary battery which obtains a separator for a secondary battery by infiltrating a non-polar organic solvent and then volatilizing the dispersion medium in the dispersion liquid.
  • the present disclosure also provides a secondary battery provided with the above-mentioned separator for a secondary battery.
  • the present disclosure also describes a method for manufacturing a secondary battery, which comprises obtaining a separator for a secondary battery by the above method for manufacturing a separator for a secondary battery and manufacturing a secondary battery using the obtained separator for a secondary battery. offer.
  • the separator for a secondary battery disclosed in the present disclosure has excellent transparency. Therefore, the secondary battery provided with the separator for the secondary battery of the present disclosure can be suitably used for information-related devices such as smartphones and notebook computers, hybrid vehicles, electric vehicles, and the like. Further, according to the manufacturing method of the present disclosure, it becomes possible to efficiently manufacture a separator for a secondary battery having excellent permeability.
  • the separator for a secondary battery of the present disclosure has a porous base material layer (A) and a heat-resistant layer (B) made of a non-woven fabric containing fine fibers and a binder having a melting point or a decomposition temperature of 200 ° C. or higher.
  • the separator for a secondary battery of the present disclosure has excellent permeability because the voids of the porous base material layer (A) are suppressed from being blocked when the heat-resistant layer (B) is formed.
  • the above formula is used in relation to the air permeability of the porous substrate (A) before the heat-resistant layer (B) is formed, the air permeability of the separator after the heat-resistant layer (B) is formed, and the thickness of the heat-resistant layer (B). It satisfies at least one of (a) and (b).
  • the value of (YX) / Z in (a) above is less than 12, preferably 11 or less, more preferably 10 or less, and the lower limit is usually 0.
  • the value according to (YX) in (b) above is less than 60, preferably 50 or less, more preferably 40 or less, and the lower limit is usually 0.
  • the air permeability of the separator for a secondary battery of the present disclosure is, for example, 100 to 650 sec / 100 mL, preferably 100 to 450 sec / 100 mL, particularly preferably 100 to 400 sec / 100 mL, and most preferably 100 to 350 sec / 100 mL. ..
  • the air permeability is within the above range, it is possible to improve the permeability, that is, the permeability of the electrolytic solution, while maintaining the insulating property of the electrode well.
  • the smaller the value of air permeability the better the transparency.
  • the separator for a secondary battery of the present disclosure is very lightweight because the heat-resistant layer (B) is formed of a non-woven fabric. Therefore, the weight of the secondary battery provided with the separator for the secondary battery of the present disclosure can be reduced, and the weight of the electric vehicle or the like using the secondary battery can also be significantly reduced.
  • the separator for a secondary battery of the present disclosure can exhibit sufficient heat resistance even if the heat-resistant layer (B) is thin, the separator for a secondary battery can be thinned, and its total thickness is It is preferably 10 to 50 ⁇ m, more preferably 12 to 30 ⁇ m. When the total thickness is within the above range, the separator for a secondary battery of the present disclosure can increase the filling density of the battery while maintaining the insulating property, and thus can contribute to the miniaturization of the secondary battery. Become.
  • the porous substrate layer (A) has voids, and the size of the voids is, for example, 0.01 to 1 ⁇ m, preferably 0.02 to 0.06 ⁇ m. If the size of the void exceeds the above range, the insulating property tends to decrease and a short circuit tends to occur easily. On the other hand, when the size of the void is less than the above range, the electric resistance tends to increase.
  • the porosity of the porous base material layer (A) is preferably, for example, 20 to 70% by volume, and particularly preferably 30 to 60% by volume. If the porosity exceeds the above range, the strength tends to be insufficient. On the other hand, when the porosity is lower than the above range, the permeability of lithium ions tends to deteriorate and the electrical resistance tends to increase.
  • the air permeability of the porous substrate layer (A) is, for example, 100 to 600 sec / 100 mL, preferably 100 to 400 sec / 100 mL, and particularly preferably 100 to 350 sec / 100 mL.
  • the air permeability exceeds the above range, the permeability of lithium ions tends to deteriorate and the electrical resistance tends to increase.
  • the air permeability is lower than the above range, the strength tends to be insufficient.
  • the porous base material layer (A) is insoluble in an electrolytic solution and has a function of softening in a high temperature environment to close voids, that is, a shutdown function. Therefore, a thermoplastic polymer is preferable as the material of the porous base material layer (A).
  • the thermoplastic polymer include polyolefins such as polyethylene and polypropylene; polyester resins such as polyethylene terephthalate; and aliphatic polyamides such as 2,6-nylon.
  • the thickness of the porous base material layer (A) is, for example, 5 to 40 ⁇ m, preferably 10 to 25 ⁇ m. If the thickness exceeds the above range, the electric resistance of the battery tends to increase and the volume capacity tends to decrease. On the other hand, when the thickness is lower than the above range, the strength tends to be insufficient.
  • the porous base material layer (A) is made porous by, for example, heating and melting the material of the porous base material (for example, polyolefin) to form an extruded film, and stretching the obtained coating film. It can be manufactured by a method or the like.
  • the surface of the porous substrate layer (A) is ozone-treated, roughened, easily adhered, antistatic, sandblasted (sandmatted), corona discharge treated, plasma treated, and chemically etched.
  • the surface treatment can be performed by one or more methods selected from water mat treatment, flame treatment, acid treatment, alkali treatment, ultraviolet irradiation treatment, silane coupling agent treatment and the like.
  • the surface of the porous substrate layer (A) is surface-treated by a method selected from ozone treatment, corona discharge treatment, plasma treatment, flame treatment, acid treatment, alkali treatment, and ultraviolet irradiation treatment, and then surface treatment is performed.
  • a method selected from ozone treatment, corona discharge treatment, plasma treatment, flame treatment, acid treatment, alkali treatment, and ultraviolet irradiation treatment is performed.
  • the silane coupling agent treatment is applied, the effect of improving the adhesion between the porous substrate layer (A) and the heat-resistant layer (B) can be obtained as compared with the case where the silane coupling agent treatment is applied alone.
  • a polar group for example, a hydroxyl group, a carbonyl group, a carboxyl group, etc.
  • the heat-resistant layer (B) is made of a non-woven fabric containing fine fibers having a melting point or decomposition temperature of 200 ° C. or higher and a binder.
  • the heat-resistant layer (B) can be formed by applying a dispersion liquid containing at least fine fibers and binder to at least one surface of the porous substrate layer (A) and volatilizing the dispersion medium.
  • the porosity of the heat-resistant layer (B) is preferably 30 to 60% by volume, more preferably 35 to 55% by volume. If the porosity exceeds the above range, heat resistance (for example, shape retention in a high temperature environment) tends to be insufficient. On the other hand, when the porosity is lower than the above range, the permeability of lithium ions tends to deteriorate and the electrical resistance tends to increase.
  • the air permeability of the heat-resistant layer (B) is, for example, 1 to 500 sec / 100 mL, preferably 1 to 300 sec / 100 mL, particularly preferably 1 to 100 sec / 100 mL, and most preferably 1 to 70 sec / 100 mL.
  • the air permeability exceeds the above range, the permeability of lithium ions tends to deteriorate and the electrical resistance tends to increase.
  • the heat resistance for example, the shape retention in a high temperature environment
  • the thickness of the heat-resistant layer (B) is, for example, 0.5 to 20 ⁇ m, and the lower limit is preferably 1 ⁇ m because it is particularly excellent in heat resistance (for example, shrinkage suppressing effect and shape retention in a high temperature environment). It is particularly preferably 2 ⁇ m and most preferably 3 ⁇ m. Further, the upper limit is preferably 15 ⁇ m, more preferably 12 ⁇ m, particularly preferably 10 ⁇ m, and most preferably 8 ⁇ m in that the filling density of the electrodes can be improved and the secondary battery can be further miniaturized. Particularly preferably, it is 5 ⁇ m.
  • the heat-resistant layer (B) is extremely lightweight and has a basis weight of, for example, 10 g / m 2 or less, and is preferably 9 g / m 2 or less, more preferably 7 g / m 2 in terms of contributing to weight reduction of the battery. Below, it is particularly preferably 6 g / m 2 or less, most preferably 5 g / m 2 or less, and particularly preferably less than 2.5 g / m 2.
  • the lower limit of the basis weight is, for example, 0.3 g / m 2 , and 0.5 g / m 2 is preferable, and 0.8 g / m 2 is particularly preferable, and 0.8 g / m 2 is particularly preferable. It is 1 g / m 2 .
  • the basis weight of the heat-resistant layer (B) can be measured according to JIS P8124.
  • the content ratio of the fine fibers and the binder in the dispersion liquid is, for example, 1 to 20 parts by weight of the binder with respect to 10 parts by weight of the fine fibers.
  • the non-volatile content concentration (that is, the total content of the fine fibers and the binder) in the dispersion liquid can be appropriately adjusted according to the thickness of the heat-resistant layer (B) to be formed, for example, 0.5 to 10 weight. %, Preferably 0.7 to 3% by weight.
  • the dispersion may contain other components (for example, a dispersant, a surfactant, etc.) in addition to the fine fibers, the binder, and the dispersion medium, if necessary.
  • the proportion of the total content of the fine fibers, the binder, and the dispersion medium is, for example, 50% by weight or more, preferably 60% by weight or more, particularly preferably 70% by weight or more, most preferably 80% by weight or more, and particularly preferably 90% by weight. It is more than% by weight. Excessive content of other components tends to make it difficult to obtain the effects of the present application.
  • the content of the organic solvent is preferably, for example, 30% by weight or less, particularly preferably 10% by weight or less, most preferably 5% by weight or less, and particularly preferably 2% by weight or less, based on the total amount of the dispersion liquid.
  • the melting point or decomposition temperature of the fine fibers that is, the melting point or the decomposition temperature when there is no melting point, is 200 ° C. or higher, preferably 250 ° C. or higher, and particularly preferably 300 ° C. or higher.
  • the upper limit of the melting point or decomposition temperature of the fine fibers is, for example, 500 ° C.
  • the average thickness (average diameter D) of the fine fibers is not particularly limited, but is, for example, 0.01 to 10 ⁇ m, and has more excellent heat resistance (for example, shape retention in a high temperature environment). Even if the thickness is thinner, a heat-resistant layer having sufficient heat resistance can be formed, which contributes to the thinning of the separator (or the miniaturization of the secondary battery), and the average thickness (average).
  • the upper limit of the diameter D) is preferably 5 ⁇ m, particularly preferably 1 ⁇ m, and most preferably 0.5 ⁇ m.
  • the lower limit of the average thickness (average diameter D) is preferably 0.03 ⁇ m, particularly preferably 0.05 ⁇ m.
  • an electron microscope image was taken for a sufficient number (for example, 100 or more) of fine fibers using an electron microscope (SEM, TEM), and the thickness (diameter) of these fine fibers was taken. ) Is measured and arithmetically averaged.
  • the average length (average length L) of the fine fibers is not particularly limited, but is, for example, 0.01 to 1 mm, and has more excellent heat resistance (for example, shape retention in a high temperature environment). , Even if it is thinner, it is possible to form a heat-resistant layer with sufficient heat resistance, which contributes to the thinning of the separator (or to the miniaturization of the secondary battery), and the average length (average).
  • the upper limit of the length L) is more preferably 0.8 mm, particularly preferably 0.5 mm, and most preferably 0.4 mm. Further, the lower limit of the average length (average length L) is more preferably 0.03 mm, and particularly preferably 0.07 mm.
  • the average length of the fine fibers is measured by taking an electron microscope image of a sufficient number (for example, 100 or more) of fine fibers using an electron microscope (SEM, TEM) and measuring the length of these fine fibers. However, it is calculated by arithmetic averaging.
  • the length of the microfibers should be measured in a linearly stretched state, but in reality, many of them are bent, so the projected diameter and projection of the microfibers from the electron microscope image using an image analyzer.
  • the average aspect ratio (average length / average thickness) of the fine fibers is not particularly limited, but is, for example, 10 to 2000, and among them, more excellent heat resistance (for example, shape retention in a high temperature environment) is obtained. Even if it has a thinner thickness, it can form a heat-resistant layer with sufficient heat resistance, which contributes to the thinning of the separator (or to the miniaturization of the secondary battery), and has an average aspect ratio.
  • the upper limit of is more preferably 1500, and particularly preferably 1000. Further, the lower limit of the average aspect ratio is more preferably 50, particularly preferably 100, most preferably 500, and particularly preferably 800.
  • fine fibers examples include cellulose fibers, aramid fibers, polyphenylene sulfide fibers, polyimide fibers, fluorine fibers, glass fibers, carbon fibers, polyparaphenylene benzoxazole fibers, polyether ether ketone fibers, liquid crystal polymer fibers and the like. .. These can be used alone or in combination of two or more.
  • the 5% weight loss temperature (T d5 ) measured at a heating rate of 10 ° C./min (in nitrogen) is 200 ° C. or higher (for example, 200). It is preferably a fiber having a temperature of about 1000 ° C.), more preferably 300 ° C. or higher, still more preferably 400 ° C. or higher, and particularly preferably 450 ° C. or higher.
  • the 5% weight loss temperature can be measured by, for example, TG / DTA (differential thermal / thermogravimetric simultaneous measurement).
  • aramid fibers are preferable in that they have excellent heat resistance and can be easily made into fine fibers.
  • the aramid fiber is a fiber composed of a polymer having a structure in which two or more aromatic rings are bonded via an amide bond (that is, a total aromatic polyamide), and the total aromatic polyamide includes a meta type and a para type. Is done.
  • Examples of the total aromatic polyamide include a polymer having a structural unit represented by the following formula (a).
  • Ar 1 and Ar 2 indicate the same or different aromatic rings, or groups in which two or more aromatic rings are bonded via a single bond or a linking group.
  • the aromatic ring include an aromatic hydrocarbon ring having 6 to 10 carbon atoms such as a benzene ring and a naphthalene ring.
  • the linking group includes, for example, a divalent hydrocarbon group (for example, a linear or branched alkylene group having 1 to 18 carbon atoms and a divalent alicyclic hydrocarbon having 3 to 18 carbon atoms. Groups, etc.), carbonyl groups (-CO-), ether bonds (-O-), ester bonds (-COO-), -NH-, -SO 2-, and the like.
  • the aromatic ring has various substituents [for example, halogen atom, alkyl group (for example, C 1-4 alkyl group), oxo group, hydroxyl group, substituted oxy group (for example, C 1-4 alkoxy group, C 1). -4 acyloxy group, etc.), carboxyl group, substituted oxycarbonyl group (eg, C 1-4 alkoxycarbonyl group), cyano group, nitro group, substituted or unsubstituted amino group (eg, mono or di-C 1-4 alkylamino). Group), sulfo group, etc.] may be possessed. Further, the aromatic ring may be condensed with a heterocyclic ring having an aromatic or non-aromatic attribute.
  • the above-mentioned aramid fiber can be produced, for example, by reacting a halide of at least one aromatic dicarboxylic acid with at least one aromatic diamine (for example, solution polymerization, surface polymerization, etc.).
  • aromatic dicarboxylic acid examples include isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, and 3,3'-biphenyldicarboxylic acid.
  • aromatic dicarboxylic acid examples include 4,4'-diphenyl ether dicarboxylic acid.
  • aromatic diamine examples include p-phenylenediamine, m-phenylenediamine, 4,4'-diaminobiphenyl, 2,4-diaminodiphenylamine, 4,4'-diaminobenzophenone, and 4,4'-diaminodiphenyl ether.
  • aromatic diamine examples include 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylamine, 4,4'-diaminodiphenylsulfone, 2,4-diaminotoluene, 2,6-naphthalenediamine, 1,5-naphthalenediamine and the like.
  • the above-mentioned aramid fiber can be produced by spinning the above-mentioned all-aromatic polyamide into a fibrous form by a well-known and conventional method (for example, through steps such as spinning, washing, and drying). Further, after being spun into a fibrous form, a crushing treatment or the like can be performed as needed.
  • a heat-resistant layer having sufficient heat resistance for example, shape retention in a high temperature environment
  • aramid fiber for example, a commercially available product such as the fine fibrous aramid "Tiara” (manufactured by Daisel Finechem Co., Ltd.) may be used.
  • Binder By adding the binder in the present disclosure to the dispersion liquid, the binder exerts an effect of imparting an appropriate viscosity to improve coatability, and further imparts adhesiveness to impart the fine fibers to the porous base material layer.
  • (A) is a compound that exerts an action of adhering to the surface.
  • the melting point or decomposition temperature of the binder is, for example, 160 ° C. or higher (preferably 180 ° C. or higher). It is particularly preferable to use a binder having a temperature of 200 ° C. or higher.
  • the upper limit of the melting point or decomposition temperature of the binder is, for example, 400 ° C.
  • the viscosity of the 1 wt% aqueous solution is preferably, for example, 100 to 5000 mPa ⁇ s, particularly preferably 500 to 3000 mPa ⁇ s, and most preferably 1000 to 2000 mPa ⁇ s. Is.
  • binder examples include non-aqueous binders such as fluorine-based binders (for example, polyvinylidene fluoride, etc.), polyester-based binders, epoxy-based binders, acrylic-based binders, vinyl ether-based binders, and water-based binders.
  • fluorine-based binders for example, polyvinylidene fluoride, etc.
  • polyester-based binders epoxy-based binders
  • acrylic-based binders acrylic-based binders
  • vinyl ether-based binders vinyl ether-based binders
  • water-based binders it is preferable to use a water-based binder because it has a small environmental load and is excellent in safety.
  • aqueous binder examples include a polysaccharide derivative (1), a compound having a structural unit represented by the following formula (2), a compound having a structural unit represented by the following formula (3), and the like. These can be used alone or in combination of two or more.
  • R represents a hydroxyl group, a carboxyl group, a phenyl group, an N-substituted or unsubstituted carbamoyl group, or a 2-oxo-1-pyrrolidinyl group.
  • n represents an integer of 2 or more
  • L represents an ether bond or a (-NH-) group.
  • N- substituted carbamoyl group -CONHCH (CH 3) 2, -CON (CH 3) such as 2 groups include N-C 1-4 alkyl-substituted carbamoyl group.
  • the above carboxyl group may form a salt with an alkali metal.
  • n is an integer of 2 or more, for example, an integer of 2 to 5, preferably an integer of 2 to 3. Therefore, the [C n H 2n ] group in the formula (3) is an alkylene group having 2 or more carbon atoms, and examples thereof include a dimethylene group, a methylmethylene group, a dimethylmethylene group, and a trimethylene group.
  • the compound having the structural unit represented by the above formula (2) and the compound having the structural unit represented by the following formula (3) are each represented by the structural unit represented by the formula (2) or the formula (3). It may have a structural unit other than the represented structural unit.
  • Examples of the compound having a structural unit represented by the above formula (2) include styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), methyl methacrylate butadiene rubber (MBR), and butadiene rubber (BR). Diene-type rubbers such as; acrylic polymers such as polyacrylic acid, sodium polyacrylate, acrylic acid / maleic acid copolymer / sodium salt, acrylic acid / sulfonic acid copolymer / sodium salt; polyacrylamide, poly-N. -Acrylamide-based polymers such as isopropylacrylamide, poly-N, N-dimethylacrylamide; polyvinylpyrrolidone and the like can be mentioned.
  • SBR styrene-butadiene rubber
  • NBR acrylonitrile-butadiene rubber
  • MRR methyl methacrylate butadiene rubber
  • BR butadiene rubber
  • Diene-type rubbers such as;
  • Examples of the compound having a structural unit represented by the above formula (3) include polyalkylene glycols such as polyethylene glycol and polypropylene glycol; polyethyleneimine and the like.
  • the polysaccharide derivative (1) is a compound obtained by polymerizing two or more monosaccharides by glycosidic bonds.
  • a compound in which glucose (for example, ⁇ -glucose or ⁇ -glucose) is polymerized by a glycosidic bond, or a derivative thereof is preferable, and in particular, cellulose, starch, glycogen, or a derivative thereof is used. At least one selected is preferred.
  • the polysaccharide derivative (1) it is particularly excellent in heat resistance to use cellulose or a derivative thereof, and by adding a small amount, excellent adhesive strength and viscosity can be imparted to the dispersion liquid. Is preferable.
  • Examples of the cellulose or its derivatives include compounds having a structural unit represented by the following formula (1-1). (In the formula, R 1 to R 3 represent the same or different alkyl groups having hydrogen atoms, hydroxyl groups or carboxyl groups and having 1 to 5 carbon atoms. The hydroxyl groups and carboxyl groups are alkali metals and salts. May be formed.)
  • alkyl group having 1 to 5 carbon atoms examples include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, an s-butyl group, a t-butyl group, a pentyl group and the like.
  • the hydroxyl group and the carboxyl group may form a salt with an alkali metal, for example, the -OH group may form a salt with sodium to form a -ONa group, and the -COOH group may form a sodium. It may form a salt to form a -COONa group.
  • cellulose derivative examples include hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, and alkali metal salts thereof (for example, sodium carboxymethyl cellulose).
  • an aqueous binder is preferable, and among them, the effect of imparting viscosity is excellent, the coatability of the dispersion can be improved by adding a small amount, and the fine fibers are made into a porous base material layer (a porous base material layer ().
  • the polysaccharide derivative (1) is preferable, and cellulose or a derivative thereof is particularly preferable, because it can exert an action of adhering to the surface of A) and is excellent in heat resistance.
  • the dispersion contains at least the fine fibers and the binder.
  • the dispersion liquid is prepared, for example, by mixing fine fibers, a binder and water, and using an ultrahigh pressure homogenizer or the like to apply a mechanical shearing force having a treatment pressure of 30 to 300 MPa to microfibrillate the fine fibers. can do.
  • the content of the fine fibers in the dispersion is, for example, 0.1 to 3.0% by weight, and in particular, an increase in air permeability can be suppressed and the permeability of the electrolytic solution can be improved.
  • the lower limit of the content of the fine fibers is preferably 0.3% by weight, particularly preferably 0.5% by weight.
  • the upper limit of the content of the fine fibers is preferably 3% by weight, particularly preferably 2.5% by weight, and most preferably 2% by weight.
  • the content of the binder in the dispersion is, for example, 0.01 to 3.0% by weight, and the lower limit of the content of the binder is preferable from the viewpoint of enabling uniform coating. Is 0.05% by weight, particularly preferably 0.08% by weight, most preferably 0.1% by weight, and particularly preferably 0.15% by weight. Further, the upper limit of the binder content is preferably 1.0% by weight, more preferably 0. In that the increase in air permeability can be suppressed and the permeability of the electrolytic solution can be improved. It is 7% by weight, particularly preferably 0.6% by weight, most preferably 0.4% by weight, and particularly preferably 0.3% by weight.
  • the content of the binder in the dispersion liquid is, for example, 10 to 200 parts by weight with respect to 100 parts by weight of the fine fibers. Excessive use of binder tends to block the voids in the separator and increase electrical resistance. Therefore, the upper limit of the binder content is preferably 160 parts by weight, particularly preferably 120 parts by weight, and particularly preferably 100 parts by weight. The lower limit of the binder content is preferably 15 parts by weight, particularly preferably 20 parts by weight, in terms of improving the adhesion to the porous base material layer (A).
  • the separator for a secondary battery of the present disclosure is particularly excellent in heat resistance (for example, shape retention in a high temperature environment).
  • the binder content is less than the above range, the porous base material layer (A) and the heat-resistant layer (B) are easily peeled off, and the shape of the porous base material layer (A) is maintained in a high temperature environment. It tends to be difficult to do.
  • the strength of the heat-resistant layer (B) tends to decrease.
  • the dispersion liquid may contain an organic solvent other than water as the dispersion medium, but the content of the organic solvent is preferably 50% by weight or less of the total amount of the dispersion medium contained in the dispersion liquid. Particularly preferably, it is 30% by weight or less, and most preferably 10% by weight or less.
  • the dispersion may contain other components (for example, a dispersant, a surfactant, a filler, etc.) in addition to the fine fibers and the binder as the non-volatile content, but the non-volatile content contained in the dispersion.
  • the ratio of the total content of the fine fibers and the binder to the total amount is, for example, 50% by weight or more, preferably 60% by weight or more, more preferably 70% by weight or more, particularly preferably 80% by weight or more, and most preferably. 90% by weight or more, particularly preferably 95% by weight or more.
  • the non-volatile content concentration in the dispersion liquid can be appropriately adjusted according to the thickness of the non-woven fabric to be formed, and is, for example, 0.5 to 5% by weight.
  • the viscosity of the dispersion liquid at a temperature of 25 ° C. and a shear rate of 100 (1 / s) is, for example, 10 to 10000 mPa ⁇ s, and is particularly preferably 50 to 5000 mPa ⁇ s in terms of enabling uniform coating. Particularly preferably, it is 150 to 3000 mPa ⁇ s.
  • a release film is attached to one surface of the porous substrate layer (A), and the porous substrate layer (A) is formed.
  • ⁇ Method (I)> In the production method (I), the release film is attached to one surface of the porous substrate layer (A), and then the release film is attached to the other surface of the porous substrate layer (A). By applying the dispersion liquid, volatilizing the dispersion medium, and then peeling the release film from the porous substrate layer (A), a separator for a secondary battery having excellent permeability can be obtained.
  • one opening of the void communicating with both sides of the porous substrate layer (A) is closed and gas is released. Since it becomes difficult to escape, the permeation of the dispersion medium and the binder into the porous base material layer (A) is suppressed, and the blockage of the voids due to the residue of the binder after the dispersion medium is volatilized is reduced. It is considered to be a thing.
  • the release film used in the production method (I) is not particularly limited as long as it can be attached to the porous base material layer (A) while the dispersion medium in the dispersion liquid is volatilized.
  • resin films polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene- Separation having an adhesive layer made of an adhesive (acrylic adhesive, urethane adhesive, silicone adhesive, polyester adhesive, rubber adhesive, etc.) on one surface of a vinyl acetate copolymer film, etc.
  • a mold film can be mentioned.
  • an aqueous binder as the binder and water as the dispersion medium in terms of low environmental load and excellent safety.
  • the method for applying the dispersion liquid is not particularly limited, and can be applied by, for example, a printing method, a coating method, or the like. Specific examples thereof include screen printing method, mask printing method, offset printing method, inkjet printing method, flexo printing method, gravure printing method, stamping, dispense, squeegee printing method, silk screen printing method, spraying, and brush coating. .. Further, it may be applied by a film applicator, a bar coater, a die coater, a comma coater, a gravure coater or the like.
  • the method for volatilizing the dispersion medium is not particularly limited, and examples thereof include heating, depressurization, and ventilation.
  • the heating temperature and heating time, decompression degree and decompression time, air volume, air velocity, air temperature, type and dryness of gas to be blown, area to be blown, direction of air blow, etc. can be arbitrarily selected. ..
  • the method for peeling the release film is not particularly limited, and a conventionally known method can be used.
  • the total thickness of the separator for the secondary battery can be further reduced, the filling density of the battery can be increased, and the secondary battery can be increased. It is preferable in that it contributes to the miniaturization of the battery.
  • the pressure at the time of pressing is, for example, 0.1 MPa or more, preferably 1 to 100 MPa, particularly preferably 5 to 50 MPa, and most preferably 10 to 30 MPa.
  • the pressing time is, for example, about 1 second to 100 minutes.
  • the heat-resistant layer (B) is pressed until the thickness is 15 ⁇ m or less (preferably 12 ⁇ m or less, more preferably 10 ⁇ m, particularly preferably 5 ⁇ m or less, most preferably 4 ⁇ m or less, particularly preferably 3 ⁇ m or less). It is preferable to do. It was
  • the press process can be performed by using a well-known and commonly used device such as a roll press machine, a hand press machine, an air press machine, and a hydraulic press machine.
  • the surface of the porous substrate layer (A) is prepared to a dyne value of 40 to 45 mN / m by surface treatment, and then the dispersion liquid is applied to the surface to disperse the medium.
  • a separator for a secondary battery having excellent permeability can be obtained.
  • the surface treatment preferably imparts a polar group (for example, a hydroxyl group, a carbonyl group, a carboxyl group, etc.) to the surface of the porous substrate layer (A), such as a corona discharge treatment or a plasma treatment.
  • a polar group for example, a hydroxyl group, a carbonyl group, a carboxyl group, etc.
  • the dyne value of the surface of the porous base material layer (A) is preferably 40 to 45 mN / m, more preferably 41 to 44 mN / m, and further preferably 42 to 43 mN / m. be.
  • the affinity of the dispersion liquid with respect to the porous base material layer (A) can be applied to the dispersion liquid, but the dispersion medium and the binder are porous. Since the adjustment is made within the range in which the penetration into the quality base material layer (A) is suppressed, it is considered that the blockage of the voids due to the residue of the binder after the dispersion medium is volatilized is reduced.
  • the dyne value is a film wetting tension check pen with a dyne number of 36 to 50 mN / m (manufactured by Pacific Chemical Co., Ltd., in increments of 2 mN / m) in a standard test room atmosphere with a temperature of 23 ° C and a relative humidity of 50%.
  • the pen tip of the pen is applied to the porous base material layer (A) and the ink of the pen is applied by moving it in one direction, and the ink is kept wet after 3 seconds. It can be measured by checking the number of dyne.
  • the surface treatment and the application of the dispersion liquid can be performed on one side or both sides of the porous base material layer (A).
  • the method of applying the binder, the dispersion medium, the dispersion liquid, and the method of volatilizing the dispersion medium in the above-mentioned production method (II) can be the same as in the case of the above-mentioned production method (I). Further, in the above-mentioned production method (II), the dispersion medium may be volatilized and then pressed, and the pressing process can be the same as in the above-mentioned production method (I).
  • the dispersion liquid is applied to one surface of the porous substrate layer (A), and low polarity or low polarity or from the other surface of the porous substrate layer (A).
  • a separator for a secondary battery having excellent permeability can be obtained.
  • the low-polarity or non-polar organic solvent has a high affinity with the porous substrate layer (A), but has a low affinity with the dispersion medium and the binder. Therefore, from the other aspect, the porous substrate has a low affinity. Since it easily permeates the layer (A) to fill the voids and suppresses the permeation of the dispersion medium and the binder into the porous base material layer (A), the binder after volatilizing the dispersion medium It is considered that the blockage of the voids due to the residue is reduced.
  • Examples of the above-mentioned low-polarity or non-polar organic solvent include aliphatic hydrocarbons (pentane, hexane, heptane, octane, decane, undecane, dodecane, octadecane, etc.) and alicyclic hydrocarbons (cyclopentane, cyclohexane, cyclo).
  • Octane, etc. aliphatic unsaturated hydrocarbons (dodecene, tridecene, tetradecene, pentadecene, hexadecene, heptadecene, octadecene, etc.), aromatic hydrocarbons (toluene, xylene, ethylbenzene, cumene, etc.), halogenated hydrocarbons (chloroform, dichloroethane, etc.) ), Halogenized aromatic hydrocarbons (orthodichlorobenzene, chlorobenzene, chloronaphthalene), ester solvents (ethyl acetate, butyl acetate), paraffinic hydrocarbons (liquid paraffin, etc.) and the like.
  • aromatic hydrocarbons toluene, xylene, ethylbenzene, cumene, etc.
  • halogenated hydrocarbons chloroform, dichloroethan
  • the permeation of the low-polarity or non-polar organic solvent into the porous substrate layer (A) is, for example, a known coating method (drop casting method, blade method, edge casting method, spraying method, brush coating method, etc.). ) Is applied to the porous base material layer (A). Further, the porous base material layer (A) is brought into contact with the impregnated material (paper, non-woven fabric, woven fabric, etc.) impregnated with the organic solvent by a single-wafer type or a continuous type using an impregnated roller, or It can also be carried out by spraying the heated steam of the organic solvent onto the porous base material layer (A) to cause dew condensation.
  • a known coating method drop casting method, blade method, edge casting method, spraying method, brush coating method, etc.
  • the low-polarity or non-polar organic solvent is a high-boiling organic solvent such as liquid paraffin and it is difficult to remove it from the separator by volatilization
  • a low-boiling low-polarity or non-polar organic solvent such as hexane is used.
  • the separator may be removed by washing with a polar organic solvent.
  • the method of applying the binder, the dispersion medium, and the dispersion liquid in the above-mentioned production method (III) and the method of volatilizing the dispersion medium can be the same as in the case of the above-mentioned production method (I). Further, in the above-mentioned production method (III), the dispersion medium may be volatilized and then pressed, and the pressing process can be the same as in the above-mentioned production method (I).
  • the method for manufacturing the separator for a secondary battery disclosed in the present disclosure may be a combination of the above (I) to (III).
  • a secondary battery is a power generation element including a positive electrode in which a positive electrode active material layer is arranged in a positive electrode current collector, a negative electrode in which a negative electrode active material layer is arranged in a negative electrode current collector, a separator, and an electrolytic solution.
  • the secondary battery of the present disclosure is included inside the exterior body, and is characterized in that the separator is the above-mentioned separator for a secondary battery.
  • the secondary battery of the present disclosure is a wound battery in which a positive electrode, a negative electrode and a separator are laminated and wound, and the battery is enclosed in a container such as a can together with an electrolytic solution, and the positive electrode, the negative electrode and the separator are laminated.
  • a laminated battery in which a sheet-like material is enclosed together with an electrolytic solution inside a relatively flexible exterior body may be used.
  • the secondary battery of the present disclosure is excellent in safety because it is provided with the above-mentioned separator for a secondary battery having excellent heat resistance (for example, shape retention in a high temperature environment). Further, the separator for the secondary battery is lightweight. Therefore, the secondary battery of the present disclosure is light. Therefore, information-related devices such as smartphones and notebook computers, hybrid vehicles, electric vehicles, and the like equipped with the secondary battery of the present disclosure can be reduced in weight while maintaining high safety. For example, an electric vehicle using the secondary battery of the present disclosure can be significantly reduced in weight, thereby dramatically improving fuel efficiency.
  • the secondary battery of the present disclosure is manufactured by a method of obtaining a separator for a secondary battery by the manufacturing methods (I) to (III) above and manufacturing a secondary battery using the obtained separator for a secondary battery. can do.
  • Example 1 Add 15.89 g of sodium carboxymethyl cellulose (CMC, dry weight loss: 5.6%, manufactured by Daisel Finechem Co., Ltd., product number: 1380) to 1484 g of water, and add a rotating revolution agitator (manufactured by Shinky Co., Ltd., product name: Awatori Rentaro,). A 1.0 wt% CMC aqueous solution was prepared by stirring at 3000 rpm for 30 minutes using model number: ARE-310).
  • CMC carboxymethyl cellulose
  • aramid fine fibers (average diameter D: 0.56 ⁇ m, average length L: 0.43 mm, average aspect ratio: 768, decomposition temperature: 400 ° C. or higher, solid content: 20.7%, manufactured by Daisel Finechem Co., Ltd. , Product name: Tiara, Product number: KY400S) 19 parts by weight of water was added to 1 part by weight, and the mixture was stirred at 2000 rpm for 5 minutes using a rotating revolution stirrer. Further, the treatment was performed using a high-pressure homogenizer (50 MPa, 30 passes) to obtain a 1.0 wt% aramid fiber aqueous dispersion.
  • a high-pressure homogenizer 50 MPa, 30 passes
  • a dispersion liquid (1) on one side of a polyethylene microporous film (dyne value 44 mN / m, thickness 20 ⁇ m, air permeability 235 sec / 100 mL, manufactured by Double Scope Co., Ltd.) as a porous substrate subjected to corona discharge treatment. ) Is applied at a rate of 240 mm / sec (coating thickness: 250 ⁇ m) using an automatic coating device (manufactured by Tester Sangyo Co., Ltd., model number: PI-1210), and then dried at 60 ° C. for 20 minutes.
  • a heat-resistant layer which is a non-woven fabric, was formed to obtain a separator, which is a laminated body (porous base material layer / heat-resistant layer).
  • the total thickness was 25 ⁇ m
  • the thickness of the heat-resistant layer was 5 ⁇ m
  • the basis weight of the heat-resistant layer was 1.80 g / m 2.
  • Example 2 Same as Example 1 except that a polyethylene microporous membrane (dyne value 42 mN / m, thickness 20 ⁇ m, air permeability 235 sec / 100 mL, manufactured by Double Scope Co., Ltd.) subjected to corona discharge treatment having different dyne values was used. And obtained a separator. The total thickness was 25 ⁇ m, the thickness of the heat-resistant layer was 5 ⁇ m, and the basis weight of the heat-resistant layer was 1.80 g / m 2.
  • Example 3 Separator in the same manner as in Example 1 except that a polyethylene microporous membrane (dyne value 44 mN / m, thickness 20 ⁇ m, air permeability 235 sec / 100 mL, manufactured by Double Scope Co., Ltd.) subjected to ozone discharge treatment was used.
  • a polyethylene microporous membrane (dyne value 44 mN / m, thickness 20 ⁇ m, air permeability 235 sec / 100 mL, manufactured by Double Scope Co., Ltd.) subjected to ozone discharge treatment was used.
  • Got The total thickness was 25 ⁇ m
  • the thickness of the heat-resistant layer was 5 ⁇ m
  • the basis weight of the heat-resistant layer was 1.80 g / m 2.
  • Example 4 Dispersion liquid on one surface of a polyethylene microporous film (dyne value 46 mN / m, thickness 20 ⁇ m, air permeability 235 sec / 100 mL, manufactured by Double Scope Co., Ltd.) as a porous substrate subjected to corona discharge treatment.
  • (1) was applied at a rate of 240 mm / sec (coating thickness: 250 ⁇ m) using an automatic coating device (manufactured by Tester Sangyo Co., Ltd., model number: PI-1210), and then hexane was added.
  • a heat-resistant layer which is a non-woven fabric, is formed by applying paper to the other surface and drying at 60 ° C.
  • the total thickness was 25 ⁇ m
  • the thickness of the heat-resistant layer was 5 ⁇ m
  • the basis weight of the heat-resistant layer was 1.80 g / m 2.
  • Example 5 Dispersion liquid on one surface of a polyethylene microporous film (dyne value 46 mN / m, thickness 20 ⁇ m, air permeability 235 sec / 100 mL, manufactured by Double Scope Co., Ltd.) as a porous substrate subjected to corona discharge treatment. (1) is applied at a rate of 240 mm / sec using an automatic coating device (manufactured by Tester Sangyo Co., Ltd., model number: PI-1210) (coating thickness: 250 ⁇ m), and then liquid paraffin is added. A heat-resistant layer, which is a non-woven fabric, was formed by applying the paper to the other surface and drying at 60 ° C.
  • the laminate (porous base material layer / heat-resistant layer) was washed with hexane and dried at 60 ° C. for 5 minutes to obtain a separator.
  • the total thickness was 25 ⁇ m
  • the thickness of the heat-resistant layer was 5 ⁇ m
  • the basis weight of the heat-resistant layer was 1.80 g / m 2.
  • Example 6 Slightly adhered to one surface of a polyethylene microporous film (dyne value 46 mN / m, thickness 20 ⁇ m, air permeability 235 sec / 100 mL, manufactured by Double Scope Co., Ltd.) as a porous substrate subjected to corona discharge treatment.
  • a polyethylene microporous film manufactured by Double Scope Co., Ltd.
  • After adhering the film manufactured by Panac Co., Ltd., TS25B
  • the total thickness was 25 ⁇ m
  • the thickness of the heat-resistant layer was 5 ⁇ m
  • the basis weight of the heat-resistant layer was 1.80 g / m 2.
  • Example 1 Example 1 except that a polyethylene microporous membrane (dyne value 46 mN / m, thickness 20 ⁇ m, air permeability 235 sec / 100 mL, manufactured by Double Scope Co., Ltd.) was used as a porous substrate subjected to corona discharge treatment. In the same manner as above, a separator was obtained. The total thickness was 25 ⁇ m, the thickness of the heat-resistant layer was 5 ⁇ m, and the basis weight of the heat-resistant layer was 1.80 g / m 2.
  • the air permeability of the separator and the basis weight of the heat-resistant layer (B) were measured by the following methods.
  • Air permeability test The air permeability was measured according to JIS P8117 using a Garley type densometer B type manufactured by Tester Sangyo Co., Ltd. The number of seconds was measured with a digital auto counter. The smaller the value of air permeability (Garley value), the higher the air permeability.
  • Basis weight of heat resistant layer (B) The basis weight was measured according to JIS P8124.
  • a porous base material layer (A) and a heat-resistant layer (B) made of a non-woven fabric containing microfibers having a melting point or a decomposition temperature of 200 ° C. or higher and a binder are included, and the following formulas (a) and (b) are included. ), A separator for a secondary battery that satisfies at least one of them.
  • [Appendix 17] The separator for a secondary battery according to any one of the appendices 1 to 16, wherein the fine fibers have an average aspect ratio (average length / average thickness) of 10 to 2000.
  • [Appendix 18] The separator for a secondary battery according to any one of the appendices 1 to 16, wherein the average aspect ratio (average length / average thickness) of the fine fibers is 800 to 1000.
  • the microfiber is at least one selected from the group consisting of fluorine fiber, glass fiber, carbon fiber, polyparaphenylene benzoxazole fiber, polyether ether ketone fiber and liquid crystal polymer fiber, Appendix 1 to 18. The separator for a secondary battery according to any one of the above.
  • the binder is at least one selected from the group consisting of a fluorine-based binder, a polyester-based binder, an epoxy-based binder, an acrylic-based binder, a vinyl ether-based binder, and a water-based binder, any one of Supplementary note 1 to 24.
  • the separator for the secondary battery described in 1.
  • At least the binder is selected from a polysaccharide derivative (1), a compound having a structural unit represented by the following formula (2), and a compound having a structural unit represented by the following formula (3).
  • R represents a hydroxyl group, a carboxyl group, a phenyl group, an N-substituted or unsubstituted carbamoyl group, or a 2-oxo-1-pyrrolidinyl group).
  • n indicates an integer of 2 or more, and L indicates an ether bond or a (-NH-) group).
  • the binder is a polysaccharide derivative (1) and is at least one selected from cellulose, starch, glycogen, and derivatives thereof.
  • [Appendix 31] The separator for a secondary battery according to any one of the appendices 1 to 30, wherein the fine fibers have an average thickness of 0.01 to 10 ⁇ m.
  • [Appendix 32] The separator for a secondary battery according to any one of the appendices 1 to 30, wherein the fine fibers have an average thickness of 0.05 to 0.5 ⁇ m.
  • [Appendix 33] The separator for a secondary battery according to any one of the appendices 1 to 32, wherein the fine fibers have an average length of 0.01 to 1 mm.
  • [Appendix 34] The separator for a secondary battery according to any one of the appendices 1 to 32, wherein the fine fibers have an average length of 0.07 to 0.4 mm.
  • a release film is attached to one surface of the porous substrate layer (A), and a dispersion liquid containing fine fibers and a binder is applied to the other surface of the porous substrate layer (A). Then, after volatilizing the dispersion medium in the dispersion liquid, the release film is peeled off from the porous base material layer (A), whereby the secondary battery according to any one of Supplementary note 1 to 48 is used.
  • the low-polarity or non-polar organic solvent is an aliphatic hydrocarbon, an alicyclic hydrocarbon, an aliphatic unsaturated hydrocarbon, an aromatic hydrocarbon, a halogenated hydrocarbon, a halogenated aromatic hydrocarbon, and the like.
  • the method for producing a separator for a secondary battery according to Appendix 53 which is at least one selected from an ester-based solvent and a paraffin-based hydrocarbon.
  • Appendix 55 The method for producing a separator for a secondary battery according to Appendix 53, wherein the low-polarity or non-polar organic solvent is liquid paraffin and / or hexane.
  • Appendix 62 The method for producing a separator for a secondary battery according to Appendix 61, wherein the dispersion medium contains 2% by weight or less of an organic solvent in the total amount of the dispersion medium.
  • a secondary battery separator is obtained by the method for manufacturing a secondary battery separator according to any one of the appendices 49 to 62, and a secondary battery is manufactured using the obtained secondary battery separator. How to manufacture a secondary battery.
  • porous base material layer (A) and the heat-resistant layer (B) made of a non-woven fabric containing microfibers having a melting point or a decomposition temperature of 200 ° C. or higher and a binder are included, and the following formulas (a) and (b) are included. ), A laminate that satisfies at least one of the above, and is used as a separator for a secondary battery.
  • the separator for a secondary battery of the present disclosure has low air permeability, is excellent in moisture permeability, and is also excellent in moisture permeability in a low temperature and low humidity environment, so that it can be particularly preferably used as a total heat exchange sheet. Further, according to the manufacturing method of the present disclosure, it becomes possible to efficiently manufacture a separator for a secondary battery having excellent permeability. Therefore, the present disclosure has industrial applicability.

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Abstract

The present invention provides a separator for secondary batteries, said separator exhibiting excellent permeability. A separator for secondary batteries according to the present disclosure comprises a porous base material layer (A) and a heat-resistant layer (B) which is formed of a nonwoven fabric that contains a binder and microfibers having a melting point or decomposition temperature of 200°C or higher; and this separator satisfies at least one of the formulae (a) and (b) described below. (a): (Y – X)/Z < 12 (b): (Y – X) < 60 In the formulae, X represents the air permeability (sec/100 mL) of the porous base material (A); Y represents the air permeability (sec/100 mL) of the separator; and Z represents the thickness (μm) of the heat-resistant layer (B).

Description

二次電池用セパレータSeparator for secondary battery
 本開示は、二次電池用セパレータ、二次電池用セパレータの製造方法、及び二次電池用セパレータを備えた二次電池に関する。本願は、2020年5月13日に日本に出願した、特願2020-084306号の優先権を主張し、その内容をここに援用する。 The present disclosure relates to a separator for a secondary battery, a method for manufacturing a separator for a secondary battery, and a secondary battery provided with a separator for a secondary battery. This application claims the priority of Japanese Patent Application No. 2020-084306 filed in Japan on May 13, 2020, the contents of which are incorporated herein by reference.
 リチウムイオン二次電池のような蓄電デバイスには、電解液を保持しながら正極と負極を絶縁するセパレータが用いられている。従って、セパレータには電気絶縁性を担保することが求められる。その他、リチウムイオンがこのセパレータを通過して移動することで電池が機能するため、透過性を担保することも求められる。 In a power storage device such as a lithium ion secondary battery, a separator that insulates a positive electrode and a negative electrode while holding an electrolytic solution is used. Therefore, the separator is required to ensure electrical insulation. In addition, since the battery functions when lithium ions move through this separator, it is also required to ensure transparency.
 更に、リチウムイオン二次電池は、電池内が異常高温となった場合には、セパレータの孔が塞がり電極間のリチウムイオンの流れを停止して安全に電池の機能を停止させる「シャットダウン機能」が求められる。また、リチウムイオンの流れを停止させた後も更に電池内の温度が上昇する場合に、セパレータが収縮(シュリンク)又は、溶融(メルトダウン)すると、電極の短絡や熱暴走が生じる恐れがある。そのため、セパレータは、異常高温環境下でも形状を保持できる耐熱性が求められる。 Furthermore, the lithium-ion secondary battery has a "shutdown function" that stops the flow of lithium ions between the electrodes and safely stops the function of the battery when the inside of the battery becomes abnormally high temperature. Desired. Further, when the temperature inside the battery rises further even after the flow of lithium ions is stopped, if the separator shrinks (shrinks) or melts (melts down), the electrodes may be short-circuited or thermal runaway may occur. Therefore, the separator is required to have heat resistance that can maintain its shape even in an abnormally high temperature environment.
 近年、リチウムイオン二次電池は軽量で高電圧・大容量という特性からスマートフォンやノートパソコンなどの情報関連機器に加え、ハイブリッド車や電気自動車にも搭載することが検討されていることから、更なる高エネルギー密度化に対応すべく、高耐熱セパレータが求められている。 In recent years, lithium-ion secondary batteries have been considered to be installed in hybrid vehicles and electric vehicles in addition to information-related equipment such as smartphones and laptop computers due to their characteristics of light weight, high voltage, and large capacity. High heat resistant separators are required to cope with high energy density.
 特許文献1には、多孔質基材と、特定の微小繊維とバインダとを含む不織布からなる耐熱層と、を含む二次電池用セパレータについて、耐熱性に優れることが記載されている。 Patent Document 1 describes that a separator for a secondary battery containing a porous base material and a heat-resistant layer made of a non-woven fabric containing specific fine fibers and a binder has excellent heat resistance.
 しかしながら、近年、二次電池に対する高性能化の要望はますます高まっており、セパレータに対しては、電気絶縁性を担保しつつ、より一層高い電解質の透過性が求められている。 However, in recent years, there has been an increasing demand for higher performance secondary batteries, and separators are required to have even higher electrolyte permeability while ensuring electrical insulation.
特開2019-149361号公報Japanese Unexamined Patent Publication No. 2019-149361
 従って、本開示の目的は、透過性に優れる二次電池用セパレータを提供することにある。
 本開示の他の目的は、透過性に優れる二次電池用セパレータの製造方法を提供することにある。
 本開示の他の目的は、透過性に優れる二次電池用セパレータを備えた二次電池を提供することにある。
Therefore, an object of the present disclosure is to provide a separator for a secondary battery having excellent permeability.
Another object of the present disclosure is to provide a method for manufacturing a separator for a secondary battery having excellent permeability.
Another object of the present disclosure is to provide a secondary battery provided with a separator for a secondary battery having excellent permeability.
 本開示の発明者等は上記課題を解決するため鋭意検討した結果、融点又は分解温度が200℃以上である微小繊維とバインダとを含む不織布からなる耐熱層(B)を、多孔質基材層(A)の表面に積層して得られる特定の構造体は透過性に優れること、そして、このような構造体は特定の方法により効率的に製造できることを見いだした。本開示はこれらの知見に基づいて完成させたものである。 As a result of diligent studies to solve the above problems, the inventors of the present disclosure have formed a heat-resistant layer (B) made of a non-woven fabric containing fine fibers having a melting point or decomposition temperature of 200 ° C. or higher and a binder into a porous substrate layer. It has been found that the specific structure obtained by laminating on the surface of (A) has excellent permeability, and that such a structure can be efficiently produced by a specific method. This disclosure has been completed based on these findings.
 すなわち、本開示は、多孔質基材層(A)と、融点又は分解温度が200℃以上である微小繊維及びバインダとを含む不織布からなる耐熱層(B)とを含み、下記式(a)、(b)の少なくとも一方を満たす、二次電池用セパレータを提供する。
 (Y-X)/Z < 12   (a)
 (Y-X) < 60     (b)
X:多孔質基材(A)の透気度(sec/100mL)
Y:セパレータの透気度(sec/100mL)
Z:耐熱層(B)の厚み(μm)
That is, the present disclosure includes a porous base material layer (A) and a heat-resistant layer (B) made of a non-woven fabric containing microfibers having a melting point or a decomposition temperature of 200 ° C. or higher and a binder, and the following formula (a). , (B) are satisfied, and a separator for a secondary battery is provided.
(YX) / Z <12 (a)
(YX) <60 (b)
X: Air permeability of the porous substrate (A) (sec / 100 mL)
Y: Air permeability of separator (sec / 100mL)
Z: Thickness (μm) of heat-resistant layer (B)
 本開示は、また、上記微小繊維がアラミド繊維である二次電池用セパレータを提供する。 The present disclosure also provides a separator for a secondary battery in which the microfibers are aramid fibers.
 本開示は、また、上記バインダが水系バインダである二次電池用セパレータを提供する。 The present disclosure also provides a separator for a secondary battery in which the above binder is a water-based binder.
 本開示は、また、上記バインダが、多糖類誘導体(1)、下記式(2)で表される構成単位を有する化合物、及び下記式(3)で表される構成単位を有する化合物から選択される少なくとも1種である二次電池用セパレータを提供する。
Figure JPOXMLDOC01-appb-C000003
(式中、Rは水酸基、カルボキシル基、フェニル基、N-置換又は無置換カルバモイル基、又は2-オキソ-1-ピロリジニル基を示す。)
Figure JPOXMLDOC01-appb-C000004
(式中、nは2以上の整数を示し、Lはエーテル結合又は(-NH-)基を示す。)
In the present disclosure, the binder is also selected from a polysaccharide derivative (1), a compound having a structural unit represented by the following formula (2), and a compound having a structural unit represented by the following formula (3). Provided is a separator for a secondary battery, which is at least one kind.
Figure JPOXMLDOC01-appb-C000003
(In the formula, R represents a hydroxyl group, a carboxyl group, a phenyl group, an N-substituted or unsubstituted carbamoyl group, or a 2-oxo-1-pyrrolidinyl group.)
Figure JPOXMLDOC01-appb-C000004
(In the formula, n represents an integer of 2 or more, and L represents an ether bond or a (-NH-) group.)
 本開示は、また、上記バインダが、セルロース、デンプン、グリコーゲン、及びこれらの誘導体から選択される少なくとも1種である二次電池用セパレータを提供する。 The present disclosure also provides a separator for a secondary battery in which the binder is at least one selected from cellulose, starch, glycogen, and derivatives thereof.
 本開示は、また、上記微小繊維の平均太さが0.01~10μm、平均長さが0.01~2mmである二次電池用セパレータを提供する。 The present disclosure also provides a separator for a secondary battery having an average thickness of 0.01 to 10 μm and an average length of 0.01 to 2 mm of the fine fibers.
 本開示は、また、上記耐熱層(B)の厚みが0.5~20μmであり、二次電池用セパレータの総厚みが10~50μmである二次電池用セパレータを提供する。 The present disclosure also provides a separator for a secondary battery in which the thickness of the heat-resistant layer (B) is 0.5 to 20 μm and the total thickness of the separator for the secondary battery is 10 to 50 μm.
 本開示は、また、上記耐熱層(B)の坪量が10g/m2以下である二次電池用セパレータを提供する。 The present disclosure also provides a separator for a secondary battery in which the basis weight of the heat-resistant layer (B) is 10 g / m 2 or less.
 本開示は、また、上記多孔質基材層(A)の一方の面に離型フィルムを貼着し、上記多孔質基材層(A)の他方の面に、微小繊維とバインダを含む分散液を塗布し、該分散液中の分散媒を揮発させてから上記離型フィルムを多孔質基材層(A)から剥離させることにより二次電池用セパレータを得る、二次電池用セパレータの製造方法を提供する。 In the present disclosure, a release film is attached to one surface of the porous substrate layer (A), and a dispersion containing fine fibers and a binder is contained on the other surface of the porous substrate layer (A). Manufacture of a separator for a secondary battery, wherein a liquid is applied, the dispersion medium in the dispersion is volatilized, and then the release film is peeled off from the porous substrate layer (A) to obtain a separator for a secondary battery. Provide a method.
 本開示は、また、上記多孔質基材層(A)の表面を表面処理によりダイン値40~45mN/mに調製し、上記表面に微小繊維とバインダを含む分散液を塗布し、該分散液中の分散媒を揮発させることにより二次電池用セパレータを得る、二次電池用セパレータの製造方法を提供する。 In the present disclosure, the surface of the porous base material layer (A) is prepared to a Dine value of 40 to 45 mN / m by surface treatment, and a dispersion liquid containing fine fibers and a binder is applied to the surface, and the dispersion liquid is applied. Provided is a method for manufacturing a separator for a secondary battery, which obtains a separator for a secondary battery by volatilizing the dispersion medium inside.
 本開示は、また、多孔質基材層(A)の一方の面に、微小繊維とバインダを含む分散液を塗布し、上記多孔質基材層(A)の他方の面から、低極性又は無極性の有機溶媒を浸透させてから、上記分散液中の分散媒を揮発させることにより、二次電池用セパレータを得る、二次電池用セパレータの製造方法を提供する。 In the present disclosure, a dispersion liquid containing microfibers and a binder is applied to one surface of the porous substrate layer (A), and low polarity or low polarity or from the other surface of the porous substrate layer (A). Provided is a method for producing a separator for a secondary battery, which obtains a separator for a secondary battery by infiltrating a non-polar organic solvent and then volatilizing the dispersion medium in the dispersion liquid.
 本開示は、また、上記二次電池用セパレータを備えた二次電池を提供する。 The present disclosure also provides a secondary battery provided with the above-mentioned separator for a secondary battery.
 本開示は、また、上記二次電池用セパレータの製造方法により二次電池用セパレータを得て、得られた二次電池用セパレータを用いて二次電池を製造する、二次電池の製造方法を提供する。 The present disclosure also describes a method for manufacturing a secondary battery, which comprises obtaining a separator for a secondary battery by the above method for manufacturing a separator for a secondary battery and manufacturing a secondary battery using the obtained separator for a secondary battery. offer.
 本開示の二次電池用セパレータは透過性に優れる。そのため、本開示の二次電池用セパレータを備えた二次電池は、スマートフォンやノートパソコンなどの情報関連機器、ハイブリッド車や電気自動車等に好適に利用できる。また、本開示の製造方法により、透過性に優れた二次電池用セパレータを効率的に製造することが可能となる。 The separator for a secondary battery disclosed in the present disclosure has excellent transparency. Therefore, the secondary battery provided with the separator for the secondary battery of the present disclosure can be suitably used for information-related devices such as smartphones and notebook computers, hybrid vehicles, electric vehicles, and the like. Further, according to the manufacturing method of the present disclosure, it becomes possible to efficiently manufacture a separator for a secondary battery having excellent permeability.
 [二次電池用セパレータ]
 本開示の二次電池用セパレータは、多孔質基材層(A)と、融点又は分解温度が200℃以上である微小繊維及びバインダを含む不織布からなる耐熱層(B)と、を有する。
[Separator for secondary battery]
The separator for a secondary battery of the present disclosure has a porous base material layer (A) and a heat-resistant layer (B) made of a non-woven fabric containing fine fibers and a binder having a melting point or a decomposition temperature of 200 ° C. or higher.
 本開示の二次電池用セパレータは、下記式(a)、(b)の少なくとも一方を満たすので、透過性に優れる。
 (Y-X)/Z < 12   (a)
 (Y-X) < 60     (b)
X:多孔質基材(A)の透気度(sec/100mL)
Y:セパレータの透気度(sec/100mL)
Z:耐熱層(B)の厚み(μm)
Since the separator for a secondary battery of the present disclosure satisfies at least one of the following formulas (a) and (b), it is excellent in transparency.
(YX) / Z <12 (a)
(YX) <60 (b)
X: Air permeability of the porous substrate (A) (sec / 100 mL)
Y: Air permeability of separator (sec / 100mL)
Z: Thickness (μm) of heat-resistant layer (B)
 本開示の二次電池用セパレータは、耐熱層(B)を形成する際に、多孔質基材層(A)の空隙について閉塞が抑制されたものであるため、優れた透過性を有する。そして、耐熱層(B)形成前の多孔質基材(A)の透気度、耐熱層(B)形成後のセパレータの透気度、及び耐熱層(B)の厚みの関係において、上記式(a)、(b)の少なくとも一方を満たすものとなる。 The separator for a secondary battery of the present disclosure has excellent permeability because the voids of the porous base material layer (A) are suppressed from being blocked when the heat-resistant layer (B) is formed. The above formula is used in relation to the air permeability of the porous substrate (A) before the heat-resistant layer (B) is formed, the air permeability of the separator after the heat-resistant layer (B) is formed, and the thickness of the heat-resistant layer (B). It satisfies at least one of (a) and (b).
 上記(a)の(Y-X)/Zに係る値は、12未満であり、好ましくは11以下、より好ましくは10以下であって、下限は、通常、0である。 The value of (YX) / Z in (a) above is less than 12, preferably 11 or less, more preferably 10 or less, and the lower limit is usually 0.
 上記(b)の(Y-X)に係る値は、60未満であり、好ましくは50以下、より好ましくは40以下であって、下限は、通常、0である。 The value according to (YX) in (b) above is less than 60, preferably 50 or less, more preferably 40 or less, and the lower limit is usually 0.
 また、本開示の二次電池用セパレータの透気度は、例えば100~650sec/100mL、好ましくは100~450sec/100mL、特に好ましくは100~400sec/100mL、最も好ましくは100~350sec/100mLである。上記透気度が上記範囲内であると、電極の絶縁性を良好に保持しつつ透過性すなわち電解液浸透性を優れたものとすることが可能となる。透気度の値が小さいほど、透過性が優れることを表す。 The air permeability of the separator for a secondary battery of the present disclosure is, for example, 100 to 650 sec / 100 mL, preferably 100 to 450 sec / 100 mL, particularly preferably 100 to 400 sec / 100 mL, and most preferably 100 to 350 sec / 100 mL. .. When the air permeability is within the above range, it is possible to improve the permeability, that is, the permeability of the electrolytic solution, while maintaining the insulating property of the electrode well. The smaller the value of air permeability, the better the transparency.
 更に、本開示の二次電池用セパレータは、耐熱層(B)が不織布によって形成されるため非常に軽量である。そのため、本開示の二次電池用セパレータを備える二次電池を軽量化することができ、上記二次電池を利用する電気自動車等も大幅に軽量化することができる。 Further, the separator for a secondary battery of the present disclosure is very lightweight because the heat-resistant layer (B) is formed of a non-woven fabric. Therefore, the weight of the secondary battery provided with the separator for the secondary battery of the present disclosure can be reduced, and the weight of the electric vehicle or the like using the secondary battery can also be significantly reduced.
 本開示の二次電池用セパレータは、耐熱層(B)が薄くても十分な耐熱性を発揮することができるため、二次電池用セパレータを薄化することが可能であり、その総厚みは、10~50μmが好ましく、より好ましくは12~30μmである。上記総厚みが上記範囲内であると、本開示の二次電池用セパレータは、絶縁性を保持しつつ電池の充填密度を高めることができるので、二次電池の小型化に資することが可能となる。 Since the separator for a secondary battery of the present disclosure can exhibit sufficient heat resistance even if the heat-resistant layer (B) is thin, the separator for a secondary battery can be thinned, and its total thickness is It is preferably 10 to 50 μm, more preferably 12 to 30 μm. When the total thickness is within the above range, the separator for a secondary battery of the present disclosure can increase the filling density of the battery while maintaining the insulating property, and thus can contribute to the miniaturization of the secondary battery. Become.
 <多孔質基材層(A)>
 上記多孔質基材層(A)は空隙を有し、その空隙の大きさは例えば0.01~1μm、好ましくは0.02~0.06μmである。空隙の大きさが上記範囲を上回ると絶縁性が低下して、短絡し易くなる傾向がある。一方、空隙の大きさが上記範囲を下回ると、電気抵抗が増大する傾向がある。
<Porous substrate layer (A)>
The porous substrate layer (A) has voids, and the size of the voids is, for example, 0.01 to 1 μm, preferably 0.02 to 0.06 μm. If the size of the void exceeds the above range, the insulating property tends to decrease and a short circuit tends to occur easily. On the other hand, when the size of the void is less than the above range, the electric resistance tends to increase.
 上記多孔質基材層(A)の空隙率は、例えば20~70体積%が好ましく、特に好ましくは30~60体積%である。空隙率が上記範囲を上回ると、強度が不十分となる傾向がある。一方、空隙率が上記範囲を下回ると、リチウムイオンの透過性が悪化し電気抵抗が増大する傾向がある。 The porosity of the porous base material layer (A) is preferably, for example, 20 to 70% by volume, and particularly preferably 30 to 60% by volume. If the porosity exceeds the above range, the strength tends to be insufficient. On the other hand, when the porosity is lower than the above range, the permeability of lithium ions tends to deteriorate and the electrical resistance tends to increase.
 上記多孔質基材層(A)の透気度は、例えば100~600sec/100mL、好ましくは100~400sec/100mL、特に好ましくは100~350sec/100mLである。透気度が上記範囲を上回ると、リチウムイオンの透過性が悪化し電気抵抗が増大する傾向がある。一方、透気度が上記範囲を下回ると、強度が不十分となる傾向がある。 The air permeability of the porous substrate layer (A) is, for example, 100 to 600 sec / 100 mL, preferably 100 to 400 sec / 100 mL, and particularly preferably 100 to 350 sec / 100 mL. When the air permeability exceeds the above range, the permeability of lithium ions tends to deteriorate and the electrical resistance tends to increase. On the other hand, when the air permeability is lower than the above range, the strength tends to be insufficient.
 上記多孔質基材層(A)は電解液に対して不溶性を示し、且つ高温環境下で軟化して空隙を閉鎖する機能、すなわちシャットダウン機能を備えることが好ましい。そのため、上記多孔質基材層(A)の材質としては熱可塑性ポリマーが好ましい。熱可塑性ポリマーとしては、例えば、ポリエチレン、ポリプロピレンなどのポリオレフィン;ポリエチレンテレフタレート等のポリエステル樹脂;2,6-ナイロン等の脂肪族ポリアミド等が挙げられる。そして、熱可塑性ポリマーのなかから、所望のシャットダウン温度に応じて適宜選択して使用することが好ましい。例えば、シャットダウン温度を150℃に設定する場合は、融点若しくは軟化温度が140~150℃である熱可塑性ポリマーを使用することが好ましい。 It is preferable that the porous base material layer (A) is insoluble in an electrolytic solution and has a function of softening in a high temperature environment to close voids, that is, a shutdown function. Therefore, a thermoplastic polymer is preferable as the material of the porous base material layer (A). Examples of the thermoplastic polymer include polyolefins such as polyethylene and polypropylene; polyester resins such as polyethylene terephthalate; and aliphatic polyamides such as 2,6-nylon. Then, it is preferable to appropriately select and use the thermoplastic polymer according to the desired shutdown temperature. For example, when the shutdown temperature is set to 150 ° C., it is preferable to use a thermoplastic polymer having a melting point or a softening temperature of 140 to 150 ° C.
 上記多孔質基材層(A)の厚みは、例えば5~40μm、好ましくは10~25μmである。厚みが上記範囲を上回ると電池の電気抵抗が上がり、また体積容量が低下する傾向がある。一方、厚みが上記範囲を下回ると、強度が不十分となる傾向がある。 The thickness of the porous base material layer (A) is, for example, 5 to 40 μm, preferably 10 to 25 μm. If the thickness exceeds the above range, the electric resistance of the battery tends to increase and the volume capacity tends to decrease. On the other hand, when the thickness is lower than the above range, the strength tends to be insufficient.
 上記多孔質基材層(A)は、例えば、多孔質基材の材料(例えば、ポリオレフィン)を加熱・溶融して押出しフィルムを形成し、得られた塗膜を延伸することによって多孔質化せしめる方法等によって製造することができる。 The porous base material layer (A) is made porous by, for example, heating and melting the material of the porous base material (for example, polyolefin) to form an extruded film, and stretching the obtained coating film. It can be manufactured by a method or the like.
 また、上記多孔質基材層(A)は、その表面に、オゾン処理、粗化処理、易接着処理、静電気防止処理、サンドブラスト処理(サンドマット処理)、コロナ放電処理、プラズマ処理、ケミカルエッチング処理、ウォーターマット処理、火炎処理、酸処理、アルカリ処理、紫外線照射処理、シランカップリング剤処理等から選択される1種又は2種以上の方法により表面処理を施すことができる。 Further, the surface of the porous substrate layer (A) is ozone-treated, roughened, easily adhered, antistatic, sandblasted (sandmatted), corona discharge treated, plasma treated, and chemically etched. The surface treatment can be performed by one or more methods selected from water mat treatment, flame treatment, acid treatment, alkali treatment, ultraviolet irradiation treatment, silane coupling agent treatment and the like.
 例えば、上記多孔質基材層(A)表面に、オゾン処理、コロナ放電処理、プラズマ処理、火炎処理、酸処理、アルカリ処理、及び紫外線照射処理から選択される方法により表面処理を施し、その後、シランカップリング剤処理を施せば、シランカップリング剤処理を単独で施す場合に比べて、多孔質基材層(A)と耐熱層(B)との密着性を向上する効果が得られる。 For example, the surface of the porous substrate layer (A) is surface-treated by a method selected from ozone treatment, corona discharge treatment, plasma treatment, flame treatment, acid treatment, alkali treatment, and ultraviolet irradiation treatment, and then surface treatment is performed. When the silane coupling agent treatment is applied, the effect of improving the adhesion between the porous substrate layer (A) and the heat-resistant layer (B) can be obtained as compared with the case where the silane coupling agent treatment is applied alone.
 本開示においては、特に、コロナ放電処理、プラズマ処理等の、上記多孔質基材層(A)の表面に極性基(例えば、水酸基、カルボニル基、カルボキシル基等)を付与することが好ましい。 In the present disclosure, it is particularly preferable to impart a polar group (for example, a hydroxyl group, a carbonyl group, a carboxyl group, etc.) to the surface of the porous substrate layer (A) such as a corona discharge treatment and a plasma treatment.
 <耐熱層(B)>
 上記耐熱層(B)は、融点又は分解温度が200℃以上である微小繊維と、バインダとを含む不織布からなる。
<Heat-resistant layer (B)>
The heat-resistant layer (B) is made of a non-woven fabric containing fine fibers having a melting point or decomposition temperature of 200 ° C. or higher and a binder.
 上記耐熱層(B)は、微小繊維及びバインダを少なくとも含む分散液を、上記多孔質基材層(A)の少なくとも一方の面に塗布し、分散媒を揮発させることにより形成することができる。 The heat-resistant layer (B) can be formed by applying a dispersion liquid containing at least fine fibers and binder to at least one surface of the porous substrate layer (A) and volatilizing the dispersion medium.
 上記耐熱層(B)の空隙率は、30~60体積%が好ましく、より好ましくは35~55体積%である。空隙率が上記範囲を上回ると、耐熱性(例えば、高温環境下における形状保持性)が不十分となる傾向がある。一方、空隙率が上記範囲を下回ると、リチウムイオンの透過性が悪化し電気抵抗が増大する傾向がある。 The porosity of the heat-resistant layer (B) is preferably 30 to 60% by volume, more preferably 35 to 55% by volume. If the porosity exceeds the above range, heat resistance (for example, shape retention in a high temperature environment) tends to be insufficient. On the other hand, when the porosity is lower than the above range, the permeability of lithium ions tends to deteriorate and the electrical resistance tends to increase.
 上記耐熱層(B)の透気度は、例えば1~500sec/100mL、好ましくは1~300sec/100mL、特に好ましくは1~100sec/100mL、最も好ましくは1~70sec/100mLである。透気度が上記範囲を上回ると、リチウムイオンの透過性が悪化し電気抵抗が増大する傾向がある。一方、透気度が上記範囲を下回ると、耐熱性(例えば、高温環境下における形状保持性)が不十分となる傾向がある。 The air permeability of the heat-resistant layer (B) is, for example, 1 to 500 sec / 100 mL, preferably 1 to 300 sec / 100 mL, particularly preferably 1 to 100 sec / 100 mL, and most preferably 1 to 70 sec / 100 mL. When the air permeability exceeds the above range, the permeability of lithium ions tends to deteriorate and the electrical resistance tends to increase. On the other hand, when the air permeability is lower than the above range, the heat resistance (for example, the shape retention in a high temperature environment) tends to be insufficient.
 上記耐熱層(B)の厚みは、例えば0.5~20μmであり、下限は、耐熱性(例えば、高温環境下における収縮抑制効果、及び形状保持性)に特に優れる点で、好ましくは1μm、特に好ましくは2μm、最も好ましくは3μmである。また、上限は、電極の充填密度を向上することができ、二次電池をより一層小型化することができる点で、好ましくは15μm、更に好ましくは12μm、特に好ましくは10μm、最も好ましくは8μm、とりわけ好ましくは5μmである。 The thickness of the heat-resistant layer (B) is, for example, 0.5 to 20 μm, and the lower limit is preferably 1 μm because it is particularly excellent in heat resistance (for example, shrinkage suppressing effect and shape retention in a high temperature environment). It is particularly preferably 2 μm and most preferably 3 μm. Further, the upper limit is preferably 15 μm, more preferably 12 μm, particularly preferably 10 μm, and most preferably 8 μm in that the filling density of the electrodes can be improved and the secondary battery can be further miniaturized. Particularly preferably, it is 5 μm.
 上記耐熱層(B)は非常に軽量であり、その坪量は例えば10g/m2以下であり、電池の軽量化に資する点において、好ましくは9g/m2以下、更に好ましくは7g/m2以下、特に好ましくは6g/m2以下、最も好ましくは5g/m2以下、とりわけ好ましくは2.5g/m2未満である。また、坪量の下限は、例えば0.3g/m2であり、なかでも形状保持性に優れる点で、0.5g/m2が好ましく、更に好ましくは0.8g/m2、特に好ましくは1g/m2である。なお、上記耐熱層(B)の坪量は、JIS P8124に準じて測定することができる。 The heat-resistant layer (B) is extremely lightweight and has a basis weight of, for example, 10 g / m 2 or less, and is preferably 9 g / m 2 or less, more preferably 7 g / m 2 in terms of contributing to weight reduction of the battery. Below, it is particularly preferably 6 g / m 2 or less, most preferably 5 g / m 2 or less, and particularly preferably less than 2.5 g / m 2. The lower limit of the basis weight is, for example, 0.3 g / m 2 , and 0.5 g / m 2 is preferable, and 0.8 g / m 2 is particularly preferable, and 0.8 g / m 2 is particularly preferable. It is 1 g / m 2 . The basis weight of the heat-resistant layer (B) can be measured according to JIS P8124.
 上記分散液中における微小繊維とバインダの含有割合は、例えば、微小繊維10重量部に対してバインダ1~20重量部である。 The content ratio of the fine fibers and the binder in the dispersion liquid is, for example, 1 to 20 parts by weight of the binder with respect to 10 parts by weight of the fine fibers.
 上記分散液中における、不揮発分濃度(すなわち、微小繊維とバインダの合計含有量)は、形成する耐熱層(B)の厚さに応じて適宜調整することができ、例えば0.5~10重量%、好ましくは0.7~3重量%である。 The non-volatile content concentration (that is, the total content of the fine fibers and the binder) in the dispersion liquid can be appropriately adjusted according to the thickness of the heat-resistant layer (B) to be formed, for example, 0.5 to 10 weight. %, Preferably 0.7 to 3% by weight.
 上記分散液には、微小繊維、バインダ、及び分散媒以外にも必要に応じて他の成分(例えば、分散剤、界面活性剤等)を含有していてもよいが、上記分散液全量における、微小繊維、バインダ、及び分散媒の合計含有量の占める割合は、例えば50重量%以上、好ましくは60重量%以上、特に好ましくは70重量%以上、最も好ましくは80重量%以上、とりわけ好ましくは90重量%以上である。他の成分を過剰に含有すると本願の効果を得ることが困難となる傾向がある。 The dispersion may contain other components (for example, a dispersant, a surfactant, etc.) in addition to the fine fibers, the binder, and the dispersion medium, if necessary. The proportion of the total content of the fine fibers, the binder, and the dispersion medium is, for example, 50% by weight or more, preferably 60% by weight or more, particularly preferably 70% by weight or more, most preferably 80% by weight or more, and particularly preferably 90% by weight. It is more than% by weight. Excessive content of other components tends to make it difficult to obtain the effects of the present application.
 また、上記分散液には、環境負荷が小さく、安全性に優れる点で、分散媒として水を使用することが好ましい。分散媒としては、水以外にも有機溶媒を含有していてもよいが有機溶媒の含有量は、上記分散液に含まれる分散媒全量(=揮発成分全量)の、例えば30重量%以下が好ましく、特に好ましくは10重量%以下、最も好ましくは5重量%以下、とりわけ好ましくは2重量%以下である。また、有機溶媒の含有量は、上記分散液全量の、例えば30重量%以下が好ましく、特に好ましくは10重量%以下、最も好ましくは5重量%以下、とりわけ好ましくは2重量%以下である。 In addition, it is preferable to use water as the dispersion medium for the dispersion liquid because it has a small environmental load and is excellent in safety. The dispersion medium may contain an organic solvent in addition to water, but the content of the organic solvent is preferably 30% by weight or less of the total amount of the dispersion medium (= total amount of volatile components) contained in the dispersion liquid. It is particularly preferably 10% by weight or less, most preferably 5% by weight or less, and particularly preferably 2% by weight or less. The content of the organic solvent is preferably, for example, 30% by weight or less, particularly preferably 10% by weight or less, most preferably 5% by weight or less, and particularly preferably 2% by weight or less, based on the total amount of the dispersion liquid.
 (微小繊維)
 上記微小繊維の融点又は分解温度、すなわち融点、又は融点がない場合は分解温度は、200℃以上であり、好ましくは250℃以上、特に好ましくは300℃以上である。尚、上記微小繊維の融点又は分解温度の上限は、例えば500℃である。
(Fine fiber)
The melting point or decomposition temperature of the fine fibers, that is, the melting point or the decomposition temperature when there is no melting point, is 200 ° C. or higher, preferably 250 ° C. or higher, and particularly preferably 300 ° C. or higher. The upper limit of the melting point or decomposition temperature of the fine fibers is, for example, 500 ° C.
 上記微小繊維の平均太さ(平均径D)は、特に限定されないが、例えば0.01~10μmであり、なかでも、より優れた耐熱性(例えば、高温環境下における形状保持性)を有し、より厚みが薄くても、十分な耐熱性を有する耐熱層を形成することができ、よりセパレータの薄化に資する(若しくは、二次電池の小型化に資する)点で、平均太さ(平均径D)の上限は、5μmが好ましく、1μmが特に好ましく、0.5μmが最も好ましい。また、平均太さ(平均径D)の下限は、0.03μmが好ましく、0.05μmが特に好ましい。尚、微小繊維の平均太さは、電子顕微鏡(SEM、TEM)を用いて十分な数(例えば、100個以上)の微小繊維について電子顕微鏡像を撮影し、これらの微小繊維の太さ(直径)を計測し、算術平均することにより求められる。 The average thickness (average diameter D) of the fine fibers is not particularly limited, but is, for example, 0.01 to 10 μm, and has more excellent heat resistance (for example, shape retention in a high temperature environment). Even if the thickness is thinner, a heat-resistant layer having sufficient heat resistance can be formed, which contributes to the thinning of the separator (or the miniaturization of the secondary battery), and the average thickness (average). The upper limit of the diameter D) is preferably 5 μm, particularly preferably 1 μm, and most preferably 0.5 μm. The lower limit of the average thickness (average diameter D) is preferably 0.03 μm, particularly preferably 0.05 μm. For the average thickness of the fine fibers, an electron microscope image was taken for a sufficient number (for example, 100 or more) of fine fibers using an electron microscope (SEM, TEM), and the thickness (diameter) of these fine fibers was taken. ) Is measured and arithmetically averaged.
 上記微小繊維の平均長さ(平均長L)は、特に限定されないが、例えば0.01~1mmであり、なかでも、より優れた耐熱性(例えば、高温環境下における形状保持性)を有し、より厚みが薄くても、十分な耐熱性を有する耐熱層を形成することができ、よりセパレータの薄化に資する(若しくは、二次電池の小型化に資する)点で、平均長さ(平均長L)の上限は、0.8mmがより好ましく、0.5mmが特に好ましく、0.4mmが最も好ましい。また、平均長さ(平均長L)の下限は、0.03mmがより好ましく、0.07mmが特に好ましい。尚、微小繊維の平均長さは、電子顕微鏡(SEM、TEM)を用いて十分な数(例えば、100個以上)の微小繊維について電子顕微鏡像を撮影し、これらの微小繊維の長さを計測し、算術平均することにより求められる。微小繊維の長さは、直線状に伸ばした状態で計測すべきであるが、現実には屈曲しているものが多いため、電子顕微鏡像から画像解析装置を用いて微小繊維の投影径及び投影面積を算出し、円柱体を仮定して下記式から算出するものとする。
   長さ=投影面積/投影径
The average length (average length L) of the fine fibers is not particularly limited, but is, for example, 0.01 to 1 mm, and has more excellent heat resistance (for example, shape retention in a high temperature environment). , Even if it is thinner, it is possible to form a heat-resistant layer with sufficient heat resistance, which contributes to the thinning of the separator (or to the miniaturization of the secondary battery), and the average length (average). The upper limit of the length L) is more preferably 0.8 mm, particularly preferably 0.5 mm, and most preferably 0.4 mm. Further, the lower limit of the average length (average length L) is more preferably 0.03 mm, and particularly preferably 0.07 mm. The average length of the fine fibers is measured by taking an electron microscope image of a sufficient number (for example, 100 or more) of fine fibers using an electron microscope (SEM, TEM) and measuring the length of these fine fibers. However, it is calculated by arithmetic averaging. The length of the microfibers should be measured in a linearly stretched state, but in reality, many of them are bent, so the projected diameter and projection of the microfibers from the electron microscope image using an image analyzer. The area shall be calculated, and it shall be calculated from the following formula assuming a cylindrical body.
Length = projected area / projected diameter
 上記微小繊維の平均アスペクト比(平均長さ/平均太さ)は、特に限定されないが、例えば10~2000であり、なかでも、より優れた耐熱性(例えば、高温環境下における形状保持性)を有し、より厚みが薄くても、十分な耐熱性を有する耐熱層を形成することができ、よりセパレータの薄化に資する(若しくは、二次電池の小型化に資する)点で、平均アスペクト比の上限は、1500がより好ましく、1000が特に好ましい。また、平均アスペクト比の下限は、50がより好ましく、100が特に好ましく、500が最も好ましく、800がとりわけ好ましい。 The average aspect ratio (average length / average thickness) of the fine fibers is not particularly limited, but is, for example, 10 to 2000, and among them, more excellent heat resistance (for example, shape retention in a high temperature environment) is obtained. Even if it has a thinner thickness, it can form a heat-resistant layer with sufficient heat resistance, which contributes to the thinning of the separator (or to the miniaturization of the secondary battery), and has an average aspect ratio. The upper limit of is more preferably 1500, and particularly preferably 1000. Further, the lower limit of the average aspect ratio is more preferably 50, particularly preferably 100, most preferably 500, and particularly preferably 800.
 上記微小繊維としては、例えば、セルロース繊維、アラミド繊維、ポリフェニレンサルファイド繊維、ポリイミド繊維、フッ素繊維、ガラス繊維、炭素繊維、ポリパラフェニレンベンズオキサゾール繊維、ポリエーテルエーテルケトン繊維、液晶ポリマー繊維等が挙げられる。これらは1種を単独で、又は2種以上を組み合わせて使用することができる。 Examples of the fine fibers include cellulose fibers, aramid fibers, polyphenylene sulfide fibers, polyimide fibers, fluorine fibers, glass fibers, carbon fibers, polyparaphenylene benzoxazole fibers, polyether ether ketone fibers, liquid crystal polymer fibers and the like. .. These can be used alone or in combination of two or more.
 上記微小繊維としては、なかでも、耐熱性に優れる繊維が好ましく、とりわけ昇温速度10℃/分(窒素中)で測定される5%重量減少温度(Td5)が200℃以上(例えば、200~1000℃)である繊維が好ましく、より好ましくは300℃以上、さらに好ましくは400℃以上、特に好ましくは450℃以上である繊維である。尚、5%重量減少温度は、例えば、TG/DTA(示差熱・熱重量同時測定)により測定できる。 Among the fine fibers, fibers having excellent heat resistance are preferable, and in particular, the 5% weight loss temperature (T d5 ) measured at a heating rate of 10 ° C./min (in nitrogen) is 200 ° C. or higher (for example, 200). It is preferably a fiber having a temperature of about 1000 ° C.), more preferably 300 ° C. or higher, still more preferably 400 ° C. or higher, and particularly preferably 450 ° C. or higher. The 5% weight loss temperature can be measured by, for example, TG / DTA (differential thermal / thermogravimetric simultaneous measurement).
 上記微小繊維としては、なかでも、アラミド繊維が耐熱性に優れ、微小繊維化が容易である点で好ましい。上記アラミド繊維は2個以上の芳香環がアミド結合を介して結合した構造を有するポリマー(すなわち、全芳香族ポリアミド)からなる繊維であり、上記全芳香族ポリアミドにはメタ型及びパラ型が含まれる。上記全芳香族ポリアミドとしては、例えば、下記式(a)で表される構成単位を有するポリマーが挙げられる。
Figure JPOXMLDOC01-appb-C000005
Among the above-mentioned fine fibers, aramid fibers are preferable in that they have excellent heat resistance and can be easily made into fine fibers. The aramid fiber is a fiber composed of a polymer having a structure in which two or more aromatic rings are bonded via an amide bond (that is, a total aromatic polyamide), and the total aromatic polyamide includes a meta type and a para type. Is done. Examples of the total aromatic polyamide include a polymer having a structural unit represented by the following formula (a).
Figure JPOXMLDOC01-appb-C000005
 上記式中、Ar1、Ar2は同一又は異なって芳香環、又は2個以上の芳香環が単結合又は連結基を介して結合した基を示す。上記芳香環としては、例えば、ベンゼン環、ナフタレン環等の炭素数6~10の芳香族炭化水素環が挙げられる。また、上記連結基としては、例えば、二価の炭化水素基(例えば、炭素数1~18の直鎖状又は分岐鎖状のアルキレン基、炭素数3~18の二価の脂環式炭化水素基等)、カルボニル基(-CO-)、エーテル結合(-O-)、エステル結合(-COO-)、-NH-、-SO2-等が挙げられる。また、上記芳香環は種々の置換基[例えば、ハロゲン原子、アルキル基(例えば、C1-4アルキル基)、オキソ基、ヒドロキシル基、置換オキシ基(例えば、C1-4アルコキシ基、C1-4アシルオキシ基等)、カルボキシル基、置換オキシカルボニル基(例えば、C1-4アルコキシカルボニル基)、シアノ基、ニトロ基、置換又は無置換アミノ基(例えば、モノ又はジC1-4アルキルアミノ基)、スルホ基等]を有していてもよい。更に、上記芳香環には芳香族性又は非芳香属性の複素環が縮合していてもよい。 In the above formula, Ar 1 and Ar 2 indicate the same or different aromatic rings, or groups in which two or more aromatic rings are bonded via a single bond or a linking group. Examples of the aromatic ring include an aromatic hydrocarbon ring having 6 to 10 carbon atoms such as a benzene ring and a naphthalene ring. The linking group includes, for example, a divalent hydrocarbon group (for example, a linear or branched alkylene group having 1 to 18 carbon atoms and a divalent alicyclic hydrocarbon having 3 to 18 carbon atoms. Groups, etc.), carbonyl groups (-CO-), ether bonds (-O-), ester bonds (-COO-), -NH-, -SO 2-, and the like. Further, the aromatic ring has various substituents [for example, halogen atom, alkyl group (for example, C 1-4 alkyl group), oxo group, hydroxyl group, substituted oxy group (for example, C 1-4 alkoxy group, C 1). -4 acyloxy group, etc.), carboxyl group, substituted oxycarbonyl group (eg, C 1-4 alkoxycarbonyl group), cyano group, nitro group, substituted or unsubstituted amino group (eg, mono or di-C 1-4 alkylamino). Group), sulfo group, etc.] may be possessed. Further, the aromatic ring may be condensed with a heterocyclic ring having an aromatic or non-aromatic attribute.
 上記アラミド繊維は、例えば、少なくとも1種の芳香族ジカルボン酸のハロゲン化物に、少なくとも1種の芳香族ジアミンを反応させる(例えば、溶液重合、界面重合等)ことにより製造することができる。 The above-mentioned aramid fiber can be produced, for example, by reacting a halide of at least one aromatic dicarboxylic acid with at least one aromatic diamine (for example, solution polymerization, surface polymerization, etc.).
 上記芳香族ジカルボン酸としては、例えば、イソフタル酸、テレフタル酸、1,4-ナフタレンジカルボン酸、2,6-ナフタレンジカルボン酸、4,4’-ビフェニルジカルボン酸、3,3’-ビフェニルジカルボン酸、4,4’-ジフェニルエーテルジカルボン酸等が挙げられる。 Examples of the aromatic dicarboxylic acid include isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, and 3,3'-biphenyldicarboxylic acid. Examples thereof include 4,4'-diphenyl ether dicarboxylic acid.
 上記芳香族ジアミンとしては、例えば、p-フェニレンジアミン、m-フェニレンジアミン、4,4’-ジアミノビフェニル、2,4-ジアミノジフェニルアミン、4,4’-ジアミノベンゾフェノン、4,4’-ジアミノジフェニルエーテル、4,4’-ジアミノジフェニルメタン、4,4’-ジアミノジフェニルアミン、4,4’-ジアミノジフェニルスルホン、2,4-ジアミノトルエン、2,6-ナフタレンジアミン、1,5-ナフタレンジアミン等が挙げられる。 Examples of the aromatic diamine include p-phenylenediamine, m-phenylenediamine, 4,4'-diaminobiphenyl, 2,4-diaminodiphenylamine, 4,4'-diaminobenzophenone, and 4,4'-diaminodiphenyl ether. Examples thereof include 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylamine, 4,4'-diaminodiphenylsulfone, 2,4-diaminotoluene, 2,6-naphthalenediamine, 1,5-naphthalenediamine and the like.
 上記アラミド繊維は、上記全芳香族ポリアミドを周知慣用の方法により(例えば、紡糸、洗浄、乾燥処理等の工程を経て)繊維状に紡糸することにより製造できる。また、繊維状に紡糸された後は、必要に応じて解砕処理等を施すことができる。本開示においては、より厚みが薄くても、十分な耐熱性(例えば、高温環境下における形状保持性)を有する耐熱層を形成することができ、よりセパレータの薄化に資する(若しくは、二次電池の小型化に資する)点で、超高圧ホモジナイザー等により強力な機械的剪断力を加えミクロフィブリル化することが好ましい。 The above-mentioned aramid fiber can be produced by spinning the above-mentioned all-aromatic polyamide into a fibrous form by a well-known and conventional method (for example, through steps such as spinning, washing, and drying). Further, after being spun into a fibrous form, a crushing treatment or the like can be performed as needed. In the present disclosure, a heat-resistant layer having sufficient heat resistance (for example, shape retention in a high temperature environment) can be formed even if the thickness is thinner, which further contributes to the thinning of the separator (or is secondary). In terms of contributing to the miniaturization of the battery), it is preferable to apply a strong mechanical shearing force to the microfibril with an ultra-high pressure homogenizer or the like.
 上記アラミド繊維としては、例えば、微小繊維状アラミド「ティアラ」(ダイセルファインケム(株)製)等の市販品を使用してもよい。 As the aramid fiber, for example, a commercially available product such as the fine fibrous aramid "Tiara" (manufactured by Daisel Finechem Co., Ltd.) may be used.
 (バインダ)
 本開示におけるバインダは、上記分散液に添加することにより、適度な粘度を付与して塗布性を向上させる効果を発揮し、更に、粘着性を付与して、上記微小繊維を多孔質基材層(A)の表面に固着させる作用を発揮する化合物である。
(Binder)
By adding the binder in the present disclosure to the dispersion liquid, the binder exerts an effect of imparting an appropriate viscosity to improve coatability, and further imparts adhesiveness to impart the fine fibers to the porous base material layer. (A) is a compound that exerts an action of adhering to the surface.
 耐熱層(B)の耐熱性を発現させる点において、耐熱性に優れたバインダを使用することは必須でないが好ましく、上記バインダとして、融点又は分解温度が、例えば160℃以上(好ましくは180℃以上、特に好ましくは200℃以上)であるバインダを使用することが好ましい。尚、バインダの融点又は分解温度の上限は、例えば400℃である。 It is not essential to use a binder having excellent heat resistance in terms of developing the heat resistance of the heat-resistant layer (B), but it is preferable, and the melting point or decomposition temperature of the binder is, for example, 160 ° C. or higher (preferably 180 ° C. or higher). It is particularly preferable to use a binder having a temperature of 200 ° C. or higher. The upper limit of the melting point or decomposition temperature of the binder is, for example, 400 ° C.
 上記バインダとしては、1重量%水溶液の粘度(25℃、60回転における)が、例えば100~5000mPa・sであることが好ましく、特に好ましくは500~3000mPa・s、最も好ましくは1000~2000mPa・sである。 As the binder, the viscosity of the 1 wt% aqueous solution (at 25 ° C. and 60 rpm) is preferably, for example, 100 to 5000 mPa · s, particularly preferably 500 to 3000 mPa · s, and most preferably 1000 to 2000 mPa · s. Is.
 上記バインダには、例えば、フッ素系バインダ(例えば、ポリフッ化ビニリデン等)、ポリエステル系バインダ、エポキシ系バインダ、アクリル系バインダ、ビニルエーテル系バインダ等の非水系バインダや、水系バインダが挙げられる。本開示においては、なかでも、環境負荷が小さく、安全性に優れる点で水系バインダを使用することが好ましい。 Examples of the binder include non-aqueous binders such as fluorine-based binders (for example, polyvinylidene fluoride, etc.), polyester-based binders, epoxy-based binders, acrylic-based binders, vinyl ether-based binders, and water-based binders. In the present disclosure, it is preferable to use a water-based binder because it has a small environmental load and is excellent in safety.
 上記水系バインダとしては、例えば、多糖類誘導体(1)、下記式(2)で表される構成単位を有する化合物、下記式(3)で表される構成単位を有する化合物等が挙げられる。これらは1種を単独で、又は2種以上を組み合わせて使用することができる。
Figure JPOXMLDOC01-appb-C000006
(式中、Rは水酸基、カルボキシル基、フェニル基、N-置換又は無置換カルバモイル基、又は2-オキソ-1-ピロリジニル基を示す。)
Figure JPOXMLDOC01-appb-C000007
(式中、nは2以上の整数を示し、Lはエーテル結合又は(-NH-)基を示す。)
Examples of the aqueous binder include a polysaccharide derivative (1), a compound having a structural unit represented by the following formula (2), a compound having a structural unit represented by the following formula (3), and the like. These can be used alone or in combination of two or more.
Figure JPOXMLDOC01-appb-C000006
(In the formula, R represents a hydroxyl group, a carboxyl group, a phenyl group, an N-substituted or unsubstituted carbamoyl group, or a 2-oxo-1-pyrrolidinyl group.)
Figure JPOXMLDOC01-appb-C000007
(In the formula, n represents an integer of 2 or more, and L represents an ether bond or a (-NH-) group.)
 上記N-置換カルバモイル基としては、-CONHCH(CH32、-CON(CH32基等の、N-C1-4アルキル置換カルバモイル基が挙げられる。 As the N- substituted carbamoyl group, -CONHCH (CH 3) 2, -CON (CH 3) such as 2 groups include N-C 1-4 alkyl-substituted carbamoyl group.
 上記カルボキシル基はアルカリ金属と塩を形成していてもよい。 The above carboxyl group may form a salt with an alkali metal.
 上記nは2以上の整数であり、例えば2~5の整数、好ましくは2~3の整数である。従って、式(3)中の[Cn2n]基は炭素数2以上のアルキレン基であり、ジメチレン基、メチルメチレン基、ジメチルメチレン基、トリメチレン基等が挙げられる。 The above n is an integer of 2 or more, for example, an integer of 2 to 5, preferably an integer of 2 to 3. Therefore, the [C n H 2n ] group in the formula (3) is an alkylene group having 2 or more carbon atoms, and examples thereof include a dimethylene group, a methylmethylene group, a dimethylmethylene group, and a trimethylene group.
 上記式(2)で表される構成単位を有する化合物、及び下記式(3)で表される構成単位を有する化合物は、それぞれ、式(2)で表される構成単位や式(3)で表される構成単位以外の構成単位を有していてもよい。 The compound having the structural unit represented by the above formula (2) and the compound having the structural unit represented by the following formula (3) are each represented by the structural unit represented by the formula (2) or the formula (3). It may have a structural unit other than the represented structural unit.
 上記式(2)で表される構成単位を有する化合物としては、例えば、スチレン・ブタジエンゴム(SBR)、アクリロニトリル・ブタジエンゴム(NBR)、メタクリル酸メチル・ブタジエンゴム(MBR)、ブタジエンゴム(BR)等のジエン形ゴム;ポリアクリル酸、ポリアクリル酸ナトリウム、アクリル酸/マレイン酸共重合体・ナトリウム塩、アクリル酸/スルホン酸共重合体・ナトリウム塩等のアクリル系ポリマー;ポリアクリルアミド、ポリ-N-イソプロピルアクリルアミド、ポリ-N,N-ジメチルアクリルアミド等のアクリルアミド系ポリマー;ポリビニルピロリドン等が挙げられる。 Examples of the compound having a structural unit represented by the above formula (2) include styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), methyl methacrylate butadiene rubber (MBR), and butadiene rubber (BR). Diene-type rubbers such as; acrylic polymers such as polyacrylic acid, sodium polyacrylate, acrylic acid / maleic acid copolymer / sodium salt, acrylic acid / sulfonic acid copolymer / sodium salt; polyacrylamide, poly-N. -Acrylamide-based polymers such as isopropylacrylamide, poly-N, N-dimethylacrylamide; polyvinylpyrrolidone and the like can be mentioned.
 上記式(3)で表される構成単位を有する化合物としては、例えば、ポリエチレングリコール、ポリプロピレングリコール等のポリアルキレングリコール;ポリエチレンイミンなどが挙げられる。 Examples of the compound having a structural unit represented by the above formula (3) include polyalkylene glycols such as polyethylene glycol and polypropylene glycol; polyethyleneimine and the like.
 上記多糖類誘導体(1)は、2個以上の単糖類がグリコシド結合によって重合してなる化合物である。本開示においては、なかでも、グルコース(例えば、α-グルコース、又はβ-グルコース)がグリコシド結合によって重合してなる化合物、若しくはその誘導体が好ましく、特に、セルロース、デンプン、グリコーゲン、若しくはこれらの誘導体から選択される少なくとも1種が好ましい。 The polysaccharide derivative (1) is a compound obtained by polymerizing two or more monosaccharides by glycosidic bonds. In the present disclosure, among them, a compound in which glucose (for example, α-glucose or β-glucose) is polymerized by a glycosidic bond, or a derivative thereof is preferable, and in particular, cellulose, starch, glycogen, or a derivative thereof is used. At least one selected is preferred.
 上記多糖類誘導体(1)としては、とりわけ、セルロース又はその誘導体を使用することが耐熱性に優れ、少量を添加することにより、上記分散液に優れた粘着力及び粘度を付与することができる点で好ましい。 As the polysaccharide derivative (1), it is particularly excellent in heat resistance to use cellulose or a derivative thereof, and by adding a small amount, excellent adhesive strength and viscosity can be imparted to the dispersion liquid. Is preferable.
 上記セルロース、又はその誘導体としては、例えば、下記式(1-1)で表される構成単位を有する化合物が挙げられる。
Figure JPOXMLDOC01-appb-C000008
(式中、R1~R3は、同一又は異なって、水素原子、ヒドロキシル基又はカルボキシル基を有する炭素数1~5のアルキル基を示す。尚、上記ヒドロキシル基及びカルボキシル基はアルカリ金属と塩を形成していてもよい。)
Examples of the cellulose or its derivatives include compounds having a structural unit represented by the following formula (1-1).
Figure JPOXMLDOC01-appb-C000008
(In the formula, R 1 to R 3 represent the same or different alkyl groups having hydrogen atoms, hydroxyl groups or carboxyl groups and having 1 to 5 carbon atoms. The hydroxyl groups and carboxyl groups are alkali metals and salts. May be formed.)
 上記炭素数1~5のアルキル基としては、例えば、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基、イソブチル基、s-ブチル基、t-ブチル基、ペンチル基、等が挙げられる。 Examples of the alkyl group having 1 to 5 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, an s-butyl group, a t-butyl group, a pentyl group and the like.
 上記ヒドロキシル基及びカルボキシル基はアルカリ金属と塩を形成していてもよく、例えば、-OH基は、ナトリウムと塩を形成して-ONa基となっていてもよく、-COOH基は、ナトリウムと塩を形成して-COONa基となっていてもよい。 The hydroxyl group and the carboxyl group may form a salt with an alkali metal, for example, the -OH group may form a salt with sodium to form a -ONa group, and the -COOH group may form a sodium. It may form a salt to form a -COONa group.
 上記セルロースの誘導体としては、具体的には、ヒドロキシエチルセルロース、ヒドロキシプロピルセルロース、カルボキシメチルセルロース、及びこれらのアルカリ金属塩(例えば、カルボキシメチルセルロースナトリウム)等が挙げられる。 Specific examples of the cellulose derivative include hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, and alkali metal salts thereof (for example, sodium carboxymethyl cellulose).
 以上より、本開示におけるバインダとしては水系バインダが好ましく、なかでも、粘性付与効果に優れ、少量の添加で上記分散液の塗布性を向上させることができる点、微小繊維を多孔質基材層(A)の表面に固着させる作用を発揮することができる点、及び、耐熱性に優れる点で、多糖類誘導体(1)が好ましく、とりわけセルロース又はその誘導体が好ましい。 From the above, as the binder in the present disclosure, an aqueous binder is preferable, and among them, the effect of imparting viscosity is excellent, the coatability of the dispersion can be improved by adding a small amount, and the fine fibers are made into a porous base material layer (a porous base material layer (). The polysaccharide derivative (1) is preferable, and cellulose or a derivative thereof is particularly preferable, because it can exert an action of adhering to the surface of A) and is excellent in heat resistance.
 (分散液)
 上記分散液は、上記微小繊維及び上記バインダを少なくとも含む。
(Dispersion)
The dispersion contains at least the fine fibers and the binder.
 上記分散液は、例えば、微小繊維とバインダと水とを混合し、超高圧ホモジナイザー等を用い、処理圧30~300MPaの機械的剪断力を加えることにより、微小繊維をマイクロフィブリル化することにより調製することができる。 The dispersion liquid is prepared, for example, by mixing fine fibers, a binder and water, and using an ultrahigh pressure homogenizer or the like to apply a mechanical shearing force having a treatment pressure of 30 to 300 MPa to microfibrillate the fine fibers. can do.
 上記分散液中における上記微小繊維の含有量は、例えば0.1~3.0重量%であり、なかでも、透気度の上昇を抑制することができ、電解液浸透性を向上することができる点において、上記微小繊維の含有量の下限値は、好ましくは0.3重量%、特に好ましくは0.5重量%である。また、上記微小繊維の含有量の上限値は、好ましくは3重量%、特に好ましくは2.5重量%、最も好ましくは2重量%である。 The content of the fine fibers in the dispersion is, for example, 0.1 to 3.0% by weight, and in particular, an increase in air permeability can be suppressed and the permeability of the electrolytic solution can be improved. The lower limit of the content of the fine fibers is preferably 0.3% by weight, particularly preferably 0.5% by weight. The upper limit of the content of the fine fibers is preferably 3% by weight, particularly preferably 2.5% by weight, and most preferably 2% by weight.
 上記分散液中における上記バインダの含有量は、例えば0.01~3.0重量%であり、なかでも、均一な塗布を可能とする点おいて、上記バインダの含有量の下限値は、好ましくは0.05重量%、特に好ましくは0.08重量%、最も好ましくは0.1重量%、とりわけ好ましくは0.15重量%である。また、透気度の上昇を抑制することができ、電解液浸透性を向上することができる点において、上記バインダの含有量の上限値は、好ましくは1.0重量%、より好ましくは0.7重量%、特に好ましくは0.6重量%、最も好ましくは0.4重量%、とりわけ好ましくは0.3重量%である。 The content of the binder in the dispersion is, for example, 0.01 to 3.0% by weight, and the lower limit of the content of the binder is preferable from the viewpoint of enabling uniform coating. Is 0.05% by weight, particularly preferably 0.08% by weight, most preferably 0.1% by weight, and particularly preferably 0.15% by weight. Further, the upper limit of the binder content is preferably 1.0% by weight, more preferably 0. In that the increase in air permeability can be suppressed and the permeability of the electrolytic solution can be improved. It is 7% by weight, particularly preferably 0.6% by weight, most preferably 0.4% by weight, and particularly preferably 0.3% by weight.
 上記分散液中における上記バインダの含有量は、上記微小繊維100重量部に対して、例えば10~200重量部である。バインダを過剰に用いるとセパレータの空隙を閉塞し、電気抵抗が増大する傾向がある。そのため、バインダの含有量の上限は、好ましくは160重量部、特に好ましくは120重量部、とりわけ好ましくは100重量部である。また、バインダの含有量の下限は、多孔質基材層(A)との密着性を向上する点において、好ましくは15重量部、特に好ましくは20重量部である。本開示においては微小繊維とバインダとを共に含有するため、微小繊維のみの場合に比べて、微小繊維間の結着性が向上して耐熱層(B)の強度が高められ、且つ、耐熱層(B)の多孔質基材層(A)への密着性が向上する。そのため、本開示の二次電池用セパレータは耐熱性(例えば、高温環境下における形状保持性)に特に優れる。一方、バインダの含有量が上記範囲を下回る場合は、多孔質基材層(A)と耐熱層(B)が剥離し易くなり、高温環境下において多孔質基材層(A)の形状を保持することが困難となる傾向がある。また、耐熱層(B)の強度が低下する傾向もある。 The content of the binder in the dispersion liquid is, for example, 10 to 200 parts by weight with respect to 100 parts by weight of the fine fibers. Excessive use of binder tends to block the voids in the separator and increase electrical resistance. Therefore, the upper limit of the binder content is preferably 160 parts by weight, particularly preferably 120 parts by weight, and particularly preferably 100 parts by weight. The lower limit of the binder content is preferably 15 parts by weight, particularly preferably 20 parts by weight, in terms of improving the adhesion to the porous base material layer (A). In the present disclosure, since the microfibers and the binder are contained together, the binding property between the microfibers is improved, the strength of the heat-resistant layer (B) is enhanced, and the heat-resistant layer is improved as compared with the case where only the microfibers are used. The adhesion of (B) to the porous base material layer (A) is improved. Therefore, the separator for a secondary battery of the present disclosure is particularly excellent in heat resistance (for example, shape retention in a high temperature environment). On the other hand, when the binder content is less than the above range, the porous base material layer (A) and the heat-resistant layer (B) are easily peeled off, and the shape of the porous base material layer (A) is maintained in a high temperature environment. It tends to be difficult to do. In addition, the strength of the heat-resistant layer (B) tends to decrease.
 上記分散液は、分散媒として、水以外にも有機溶媒を含有していてもよいが有機溶媒の含有量は、分散液に含まれる分散媒全量の、例えば50重量%以下であることが好ましく、特に好ましくは30重量%以下、最も好ましくは10重量%以下である。 The dispersion liquid may contain an organic solvent other than water as the dispersion medium, but the content of the organic solvent is preferably 50% by weight or less of the total amount of the dispersion medium contained in the dispersion liquid. Particularly preferably, it is 30% by weight or less, and most preferably 10% by weight or less.
 上記分散液は、不揮発分として上記微小繊維及び上記バインダ以外にも他の成分(例えば、分散剤、界面活性剤、フィラー等)を含有していてもよいが、上記分散液に含まれる不揮発分全量における、上記微小繊維及び上記バインダの合計含有量の占める割合は、例えば50重量%以上、好ましくは60重量%以上、更に好ましくは70重量%以上、特に好ましくは80重量%以上、最も好ましくは90重量%以上、とりわけ好ましくは95重量%以上である。 The dispersion may contain other components (for example, a dispersant, a surfactant, a filler, etc.) in addition to the fine fibers and the binder as the non-volatile content, but the non-volatile content contained in the dispersion. The ratio of the total content of the fine fibers and the binder to the total amount is, for example, 50% by weight or more, preferably 60% by weight or more, more preferably 70% by weight or more, particularly preferably 80% by weight or more, and most preferably. 90% by weight or more, particularly preferably 95% by weight or more.
 上記分散液中の不揮発分濃度は、形成する不織布の厚さに応じて適宜調整することができるが、例えば0.5~5重量%である。 The non-volatile content concentration in the dispersion liquid can be appropriately adjusted according to the thickness of the non-woven fabric to be formed, and is, for example, 0.5 to 5% by weight.
 上記分散液の、温度25℃、せん断速度100(1/s)における粘度は、例えば10~10000mPa・sであり、なかでも、均一な塗布を可能とする点において、好ましくは50~5000mPa・s、特に好ましくは150~3000mPa・sである。 The viscosity of the dispersion liquid at a temperature of 25 ° C. and a shear rate of 100 (1 / s) is, for example, 10 to 10000 mPa · s, and is particularly preferably 50 to 5000 mPa · s in terms of enabling uniform coating. Particularly preferably, it is 150 to 3000 mPa · s.
 [二次電池用セパレータの製造方法]
 上記多孔質基材層(A)に上記分散液を塗布する際に、上記バインダが、上記分散媒とともに上記多孔質基材層(A)に浸透すると、分散媒を揮発させた後に残留したバインダが空隙を閉塞するので、上記多孔質基材層(A)の透気性が低下し、二次電池用セパレータの透気性が劣ったものになりやすい。本開示の二次電池用セパレータの製造方法は、上記分散液を塗布する際に、上記分散媒及び上記バインダの上記多孔質基材層(A)への浸透を抑制することによって二次電池用セパレータの透気性を優れたものにできる。
[Manufacturing method of separator for secondary battery]
When the binder permeates the porous base material layer (A) together with the dispersion medium when the dispersion liquid is applied to the porous base material layer (A), the binder remaining after the dispersion medium is volatilized. Closes the voids, so that the air permeability of the porous base material layer (A) is lowered, and the air permeability of the separator for a secondary battery tends to be inferior. The method for producing a separator for a secondary battery of the present disclosure is for a secondary battery by suppressing the penetration of the dispersion medium and the binder into the porous base material layer (A) when the dispersion liquid is applied. The air permeability of the separator can be improved.
 すなわち、本開示の二次電池用セパレータの製造方法は、(I)上記多孔質基材層(A)の一方の面に離型フィルムを貼着し、上記多孔質基材層(A)の他方の面に、上記分散液を塗布し、該分散液中の分散媒を揮発させてから上記離型フィルムを多孔質基材層(A)から剥離させる製造方法、(II)上記多孔質基材層(A)の表面を表面処理によりダイン値40~45mN/mに調製し、上記表面に上記分散液を塗布し、該分散液中の分散媒を揮発させる製造方法、又は、(III)上記多孔質基材層(A)の一方の面に、上記分散液を塗布し、上記多孔質基材層(A)の他方の面から、低極性又は無極性の有機溶媒を浸透させてから、上記分散液中の分散媒を揮発させる製造方法であり、透過性に優れた二次電池用セパレータを製造することができる。 That is, in the method for producing a separator for a secondary battery of the present disclosure, (I) a release film is attached to one surface of the porous substrate layer (A), and the porous substrate layer (A) is formed. A production method in which the dispersion liquid is applied to the other surface, the dispersion medium in the dispersion liquid is volatilized, and then the release film is peeled off from the porous base material layer (A), (II) the porous group. A production method in which the surface of the material layer (A) is prepared to a dyne value of 40 to 45 mN / m by surface treatment, the dispersion liquid is applied to the surface, and the dispersion medium in the dispersion liquid is volatilized, or (III). After applying the dispersion liquid to one surface of the porous substrate layer (A) and allowing a low-polarity or non-polar organic solvent to permeate from the other surface of the porous substrate layer (A). This is a production method for volatilizing the dispersion medium in the dispersion liquid, and can produce a separator for a secondary battery having excellent permeability.
 <方法(I)>
 上記(I)の製造方法においては、上記多孔質基材層(A)の一方の面に離型フィルムを貼着してから、上記多孔質基材層(A)の他方の面に、上記分散液を塗布し、分散媒を揮発させてから上記離型フィルムを多孔質基材層(A)から剥離させることによって、透過性を優れた二次電池用セパレータを得ることができる。
<Method (I)>
In the production method (I), the release film is attached to one surface of the porous substrate layer (A), and then the release film is attached to the other surface of the porous substrate layer (A). By applying the dispersion liquid, volatilizing the dispersion medium, and then peeling the release film from the porous substrate layer (A), a separator for a secondary battery having excellent permeability can be obtained.
 上記多孔質基材層(A)の一方の面に離型フィルムを貼着することによって、上記多孔質基材層(A)の両面を連通する空隙の一方の開口部が閉鎖されて気体が逃げにくくなるので、上記分散媒及び上記バインダの上記多孔質基材層(A)への浸透が抑制され、上記分散媒を揮発させた後の上記バインダの残留に起因する空隙の閉塞が低減するものと考えられる。 By attaching the release film to one surface of the porous substrate layer (A), one opening of the void communicating with both sides of the porous substrate layer (A) is closed and gas is released. Since it becomes difficult to escape, the permeation of the dispersion medium and the binder into the porous base material layer (A) is suppressed, and the blockage of the voids due to the residue of the binder after the dispersion medium is volatilized is reduced. It is considered to be a thing.
 上記(I)の製造方法に用いる離型フィルムは、上記分散液中の分散媒を揮発させる間、上記多孔質基材層(A)に貼着しておけるものであればよく、特に制限されないが、例えば、樹脂フィルム(ポリエチレンフィルム、ポリプロピレンフィルム、ポリブテンフィルム、ポリブタジエンフィルム、ポリメチルペンテンフィルム、ポリ塩化ビニルフィルム、塩化ビニル共重合体フィルム、ポリエチレンテレフタレートフィルム、ポリブチレンテレフタレートフィルム、ポリウレタンフィルム、エチレン-酢酸ビニル共重合体フィルム等)の一方の面に粘着剤(アクリル系粘着剤、ウレタン系粘着剤、シリコーン系粘着剤、ポリエステル系粘着剤、ゴム系粘着剤等)からなる粘着剤層を有する離型フィルムが挙げられる。 The release film used in the production method (I) is not particularly limited as long as it can be attached to the porous base material layer (A) while the dispersion medium in the dispersion liquid is volatilized. However, for example, resin films (polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene- Separation having an adhesive layer made of an adhesive (acrylic adhesive, urethane adhesive, silicone adhesive, polyester adhesive, rubber adhesive, etc.) on one surface of a vinyl acetate copolymer film, etc. A mold film can be mentioned.
 上記分散液について、バインダとして水系バインダを使用し、分散媒として水を使用することが、環境負荷が小さく、安全性に優れる点で好ましい。 For the above dispersion, it is preferable to use an aqueous binder as the binder and water as the dispersion medium in terms of low environmental load and excellent safety.
 上記分散液を塗布する方法としては、特に制限がなく、例えば、印刷法、コーティング法等により行うことができる。具体的には、スクリーン印刷法、マスク印刷法、オフセット印刷法、インクジェット印刷法、フレキソ印刷法、グラビア印刷法、スタンピング、ディスペンス、スキージ印刷法、シルクスクリーン印刷法、噴霧、刷毛塗り等が挙げられる。また、フィルムアプリケーター、バーコーター、ダイコーター、コンマコーター、グラビアコーター等により塗布してもよい。 The method for applying the dispersion liquid is not particularly limited, and can be applied by, for example, a printing method, a coating method, or the like. Specific examples thereof include screen printing method, mask printing method, offset printing method, inkjet printing method, flexo printing method, gravure printing method, stamping, dispense, squeegee printing method, silk screen printing method, spraying, and brush coating. .. Further, it may be applied by a film applicator, a bar coater, a die coater, a comma coater, a gravure coater or the like.
 分散媒を揮発させる方法としては、特に限定されないが、加熱、減圧、送風等の方法が挙げられる。加熱温度や加熱時間、減圧度や減圧時間、送風量、送風速度、送風温度、送風する気体の種類や乾燥度、送風する対象となる領域、送風の方向等は、任意に選択することができる。 The method for volatilizing the dispersion medium is not particularly limited, and examples thereof include heating, depressurization, and ventilation. The heating temperature and heating time, decompression degree and decompression time, air volume, air velocity, air temperature, type and dryness of gas to be blown, area to be blown, direction of air blow, etc. can be arbitrarily selected. ..
 離型フィルムを剥離させる方法は、特に限定されず、従来公知の方法を用いることができる。 The method for peeling the release film is not particularly limited, and a conventionally known method can be used.
 また、本開示においては、分散媒を揮発させた後、プレスすることが、更に二次電池用セパレータの総厚みを薄化することができ、電池の充填密度を高めることができ、二次電池の小型化に資する点において好ましい。プレス時の圧力は、例えば、0.1MPa以上であり、好ましくは1~100MPa、特に好ましくは5~50MPa、最も好ましくは10~30MPaである。また、プレス時間は、例えば1秒間~100分間程度である。 Further, in the present disclosure, by volatilizing the dispersion medium and then pressing the dispersion medium, the total thickness of the separator for the secondary battery can be further reduced, the filling density of the battery can be increased, and the secondary battery can be increased. It is preferable in that it contributes to the miniaturization of the battery. The pressure at the time of pressing is, for example, 0.1 MPa or more, preferably 1 to 100 MPa, particularly preferably 5 to 50 MPa, and most preferably 10 to 30 MPa. The pressing time is, for example, about 1 second to 100 minutes.
 上記プレス処理において、例えば、耐熱層(B)の厚みが15μm以下(好ましくは12μm以下、更に好ましくは10μm、特に好ましくは5μm以下、最も好ましくは4μm以下、とりわけ好ましくは3μm以下)となるまでプレスすることが好ましい。  In the above press treatment, for example, the heat-resistant layer (B) is pressed until the thickness is 15 μm or less (preferably 12 μm or less, more preferably 10 μm, particularly preferably 5 μm or less, most preferably 4 μm or less, particularly preferably 3 μm or less). It is preferable to do. It was
 上記プレス処理は、例えば、ロールプレス機、ハンドプレス機、エアープレス機、油圧プレス機等の周知慣用の装置を利用して行うことができる。 The press process can be performed by using a well-known and commonly used device such as a roll press machine, a hand press machine, an air press machine, and a hydraulic press machine.
 <方法(II)>
 上記(II)の製造方法においては、上記多孔質基材層(A)の表面を表面処理によりダイン値40~45mN/mに調製してから、上記表面に上記分散液を塗布し、分散媒を揮発させることによって、透過性を優れた二次電池用セパレータを得ることができる。
<Method (II)>
In the production method (II), the surface of the porous substrate layer (A) is prepared to a dyne value of 40 to 45 mN / m by surface treatment, and then the dispersion liquid is applied to the surface to disperse the medium. By volatilizing the above, a separator for a secondary battery having excellent permeability can be obtained.
 上記表面処理は、コロナ放電処理、プラズマ処理等の、上記多孔質基材層(A)の表面に極性基(例えば、水酸基、カルボニル基、カルボキシル基等)を付与するものであることが好ましい。 The surface treatment preferably imparts a polar group (for example, a hydroxyl group, a carbonyl group, a carboxyl group, etc.) to the surface of the porous substrate layer (A), such as a corona discharge treatment or a plasma treatment.
 上記表面処理は、上記多孔質基材層(A)の表面のダイン値を、40~45mN/mとすることが好ましく、より好ましくは41~44mN/m、更に好ましくは42~43mN/mである。 In the surface treatment, the dyne value of the surface of the porous base material layer (A) is preferably 40 to 45 mN / m, more preferably 41 to 44 mN / m, and further preferably 42 to 43 mN / m. be.
 上記ダイン値を上記範囲内とすることにより、上記多孔質基材層(A)に対する上記分散液の親和性が、上記分散液の塗布が可能ではあるが、上記分散媒及び上記バインダの上記多孔質基材層(A)への浸透が抑制される範囲内に調整されるので、上記分散媒を揮発させた後の上記バインダの残留に起因する空隙の閉塞が低減するものと考えられる。 By setting the dyne value within the above range, the affinity of the dispersion liquid with respect to the porous base material layer (A) can be applied to the dispersion liquid, but the dispersion medium and the binder are porous. Since the adjustment is made within the range in which the penetration into the quality base material layer (A) is suppressed, it is considered that the blockage of the voids due to the residue of the binder after the dispersion medium is volatilized is reduced.
 なお、ダイン値は、温度23℃、相対湿度50%の標準試験室雰囲気中で、ダイン数36~50mN/mのフィルムぬれ張力チェックペン(パシフィック化学(株)製、ダイン数2mN/mきざみ)のペン先を、多孔質基材層(A)にあて、一方向に移動させることでペンのインクを塗布し、3秒後にインクのぬれが保たれている、最も高いフィルムぬれ張力チェックペンのダイン数を確認することによって測定できる。 The dyne value is a film wetting tension check pen with a dyne number of 36 to 50 mN / m (manufactured by Pacific Chemical Co., Ltd., in increments of 2 mN / m) in a standard test room atmosphere with a temperature of 23 ° C and a relative humidity of 50%. The pen tip of the pen is applied to the porous base material layer (A) and the ink of the pen is applied by moving it in one direction, and the ink is kept wet after 3 seconds. It can be measured by checking the number of dyne.
 上記表面処理及び上記分散液の塗布は、上記多孔質基材層(A)の片面又は両面に対して行うことができる。 The surface treatment and the application of the dispersion liquid can be performed on one side or both sides of the porous base material layer (A).
 上記(II)の製造方法における、バインダ、分散媒、分散液を塗布する方法、及び分散媒を揮発させる方法は、上記(I)の製造方法の場合と同様にすることができる。また、上記(II)の製造方法においても分散媒を揮発させた後にプレスをしてもよく、プレス処理についても上記(I)の製造方法の場合と同様にすることができる。 The method of applying the binder, the dispersion medium, the dispersion liquid, and the method of volatilizing the dispersion medium in the above-mentioned production method (II) can be the same as in the case of the above-mentioned production method (I). Further, in the above-mentioned production method (II), the dispersion medium may be volatilized and then pressed, and the pressing process can be the same as in the above-mentioned production method (I).
 <方法(III)>
 上記(III)の製造方法においては、上記多孔質基材層(A)の一方の面に、上記分散液を塗布し、上記多孔質基材層(A)の他方の面から、低極性又は無極性の有機溶媒を浸透させてから、上記分散媒を揮発させることによって、透過性を優れた二次電池用セパレータを得ることができる。
<Method (III)>
In the production method (III), the dispersion liquid is applied to one surface of the porous substrate layer (A), and low polarity or low polarity or from the other surface of the porous substrate layer (A). By infiltrating a non-polar organic solvent and then volatilizing the dispersion medium, a separator for a secondary battery having excellent permeability can be obtained.
 低極性又は無極性の有機溶媒は、上記多孔質基材層(A)との親和性が高い一方、上記分散媒及びバインダとの親和性が低いことから、他方の面から上記多孔質基材層(A)に容易に浸透して空隙を充填し、上記分散媒及びバインダの上記多孔質基材層(A)への浸透を抑制するので、上記分散媒を揮発させた後の上記バインダの残留に起因する空隙の閉塞が低減するものと考えられる。 The low-polarity or non-polar organic solvent has a high affinity with the porous substrate layer (A), but has a low affinity with the dispersion medium and the binder. Therefore, from the other aspect, the porous substrate has a low affinity. Since it easily permeates the layer (A) to fill the voids and suppresses the permeation of the dispersion medium and the binder into the porous base material layer (A), the binder after volatilizing the dispersion medium It is considered that the blockage of the voids due to the residue is reduced.
 上記の低極性又は無極性の有機溶媒としては、例えば、脂肪族炭化水素(ペンタン、ヘキサン、ヘプタン、オクタン、デカン、ウンデカン、ドデカン、オクタデカン等)、脂環式炭化水素(シクロペンタン、シクロヘキサン、シクロオクタン等)、脂肪族不飽和炭化水素(ドデセン、トリデセン、テトラデセン、ペンタデセン、ヘキサデセン、ヘプタデセン、オクタデセン等)、芳香族炭化水素(トルエン、キシレン、エチルベンゼン、クメン等)、ハロゲン化炭化水素(クロロホルム、ジクロロエタン)、ハロゲン化芳香族炭化水素(オルトジクロロベンゼン、クロロベンゼン、クロロナフタレン)、エステル系溶媒(酢酸エチル、酢酸ブチル)、パラフィン系炭化水素(流動パラフィン等)などが挙げられる。 Examples of the above-mentioned low-polarity or non-polar organic solvent include aliphatic hydrocarbons (pentane, hexane, heptane, octane, decane, undecane, dodecane, octadecane, etc.) and alicyclic hydrocarbons (cyclopentane, cyclohexane, cyclo). Octane, etc.), aliphatic unsaturated hydrocarbons (dodecene, tridecene, tetradecene, pentadecene, hexadecene, heptadecene, octadecene, etc.), aromatic hydrocarbons (toluene, xylene, ethylbenzene, cumene, etc.), halogenated hydrocarbons (chloroform, dichloroethane, etc.) ), Halogenized aromatic hydrocarbons (orthodichlorobenzene, chlorobenzene, chloronaphthalene), ester solvents (ethyl acetate, butyl acetate), paraffinic hydrocarbons (liquid paraffin, etc.) and the like.
 上記の低極性又は無極性の有機溶媒の上記多孔質基材層(A)への浸透は、例えば、公知の塗布法(ドロップキャスト法、ブレード法、エッジキャスト法、噴霧法、刷毛塗り法等)を用いた上記溶媒の上記多孔質基材層(A)への塗布によって行うことができる。また、上記有機溶媒を含浸した含浸材(紙、不織布、織布等)に上記多孔質基材層(A)を枚葉式で、若しくは含浸ローラーを用いた連続式で接触させることによって、あるいは、上記有機溶媒の加熱蒸気を上記多孔質基材層(A)に吹き付けて結露させることによって行うこともできる。 The permeation of the low-polarity or non-polar organic solvent into the porous substrate layer (A) is, for example, a known coating method (drop casting method, blade method, edge casting method, spraying method, brush coating method, etc.). ) Is applied to the porous base material layer (A). Further, the porous base material layer (A) is brought into contact with the impregnated material (paper, non-woven fabric, woven fabric, etc.) impregnated with the organic solvent by a single-wafer type or a continuous type using an impregnated roller, or It can also be carried out by spraying the heated steam of the organic solvent onto the porous base material layer (A) to cause dew condensation.
 上記低極性又は無極性の有機溶媒が、例えば流動パラフィンなどの高沸点の有機溶媒であって、上記セパレータから揮発による除去が困難である場合には、例えばヘキサンなどの低沸点の低極性又は無極性の有機溶媒を用いて上記セパレータを洗浄することにより除去してもよい。 When the low-polarity or non-polar organic solvent is a high-boiling organic solvent such as liquid paraffin and it is difficult to remove it from the separator by volatilization, a low-boiling low-polarity or non-polar organic solvent such as hexane is used. The separator may be removed by washing with a polar organic solvent.
 上記(III)の製造方法における、バインダ、分散媒、分散液を塗布する方法、及び、分散媒を揮発させる方法は、上記(I)の製造方法の場合と同様にすることができる。また、上記(III)の製造方法においても分散媒を揮発させた後にプレスをしてもよく、プレス処理についても上記(I)の製造方法の場合と同様にすることができる。 The method of applying the binder, the dispersion medium, and the dispersion liquid in the above-mentioned production method (III) and the method of volatilizing the dispersion medium can be the same as in the case of the above-mentioned production method (I). Further, in the above-mentioned production method (III), the dispersion medium may be volatilized and then pressed, and the pressing process can be the same as in the above-mentioned production method (I).
 本開示の二次電池用セパレータの製造方法は、上記(I)~(III)を組み合わせたものであってもよい。 The method for manufacturing the separator for a secondary battery disclosed in the present disclosure may be a combination of the above (I) to (III).
 [二次電池]
 二次電池とは、正極活物質層が正極集電体に配置された正極と、負極活物質層が負極集電体に配置された負極と、セパレータと、電解液とを含む発電要素を、外装体内部に含む
ものであり、本開示の二次電池は、上記セパレータが上述の二次電池用セパレータであることを特徴とする。
[Secondary battery]
A secondary battery is a power generation element including a positive electrode in which a positive electrode active material layer is arranged in a positive electrode current collector, a negative electrode in which a negative electrode active material layer is arranged in a negative electrode current collector, a separator, and an electrolytic solution. The secondary battery of the present disclosure is included inside the exterior body, and is characterized in that the separator is the above-mentioned separator for a secondary battery.
 本開示の二次電池は、正極、負極及びセパレータを積層して巻回したものを、電解液と共に缶などの容器に封入した巻回型電池であっても、正極、負極及びセパレータを積層したシート状物を、電解液と共に、比較的柔軟な外装体内部に封じ込めた積層型電池であってもよい。 The secondary battery of the present disclosure is a wound battery in which a positive electrode, a negative electrode and a separator are laminated and wound, and the battery is enclosed in a container such as a can together with an electrolytic solution, and the positive electrode, the negative electrode and the separator are laminated. A laminated battery in which a sheet-like material is enclosed together with an electrolytic solution inside a relatively flexible exterior body may be used.
 本開示の二次電池は、耐熱性(例えば、高温環境下における形状保持性)に優れた上述の二次電池用セパレータを備えるため安全性に優れる。また、上記二次電池用セパレータは軽量である。そのため、本開示の二次電池は軽い。そのため、本開示の二次電池を備える、スマートフォンやノートパソコンなどの情報関連機器、ハイブリッド車や電気自動車等を、安全性を高く維持しつつ、軽量化することができる。例えば、本開示の二次電池を利用する電気自動車は、大幅な軽量化が可能であり、それにより燃費を飛躍的に向上することができる。 The secondary battery of the present disclosure is excellent in safety because it is provided with the above-mentioned separator for a secondary battery having excellent heat resistance (for example, shape retention in a high temperature environment). Further, the separator for the secondary battery is lightweight. Therefore, the secondary battery of the present disclosure is light. Therefore, information-related devices such as smartphones and notebook computers, hybrid vehicles, electric vehicles, and the like equipped with the secondary battery of the present disclosure can be reduced in weight while maintaining high safety. For example, an electric vehicle using the secondary battery of the present disclosure can be significantly reduced in weight, thereby dramatically improving fuel efficiency.
 本開示の二次電池は、上記(I)~(III)の製造方法により二次電池用セパレータを得て、得られた二次電池用セパレータを用いて二次電池を製造する方法によって、製造することができる。 The secondary battery of the present disclosure is manufactured by a method of obtaining a separator for a secondary battery by the manufacturing methods (I) to (III) above and manufacturing a secondary battery using the obtained separator for a secondary battery. can do.
 上記の各実施形態における各構成及びそれらの組み合わせ等は、一例であって、本開示の主旨から逸脱しない範囲内で、適宜、構成の付加、省略、置換、及びその他の変更が可能である。本開示に係る発明は、実施形態によって限定されることはなく、特許請求の範囲によってのみ限定される。 The configurations and combinations thereof in each of the above embodiments are examples, and the configurations can be added, omitted, replaced, and other changes as appropriate without departing from the gist of the present disclosure. The invention according to the present disclosure is not limited by embodiments, but only by the claims.
 また、本明細書に開示された各々の態様は、本明細書に開示された他のいかなる特徴とも組み合わせることができる。 Also, each aspect disclosed herein can be combined with any other feature disclosed herein.
 以下、実施例により本開示をより具体的に説明するが、本開示はこれらの実施例により限定されるものではない。 Hereinafter, the present disclosure will be described in more detail by way of examples, but the present disclosure is not limited to these examples.
 [実施例1]
 水1484gにカルボキシメチルセルロースナトリウム(CMC、乾燥減量:5.6%、ダイセルファインケム(株)製、品番:1380)を15.89g加え、自転公転撹拌機(シンキー社製、品名:あわとり練太郎、型番:ARE-310)を用いて、3000rpmで30分撹拌することで1.0重量%CMC水溶液を調製した。
[Example 1]
Add 15.89 g of sodium carboxymethyl cellulose (CMC, dry weight loss: 5.6%, manufactured by Daisel Finechem Co., Ltd., product number: 1380) to 1484 g of water, and add a rotating revolution agitator (manufactured by Shinky Co., Ltd., product name: Awatori Rentaro,). A 1.0 wt% CMC aqueous solution was prepared by stirring at 3000 rpm for 30 minutes using model number: ARE-310).
 次に、アラミド微細繊維(平均径D:0.56μm、平均長L:0.43mm、平均アスペクト比:768、分解温度:400℃以上、固形分:20.7%、ダイセルファインケム(株)製、商品名:ティアラ、品番:KY400S)1重量部に水19重量部を加え、自転公転撹拌機を用いて2000rpmで5分撹拌した。さらに、高圧ホモジナイザーを用いて処理(50MPa、30パス)することにより1.0重量%アラミド繊維水分散液を得た。 Next, aramid fine fibers (average diameter D: 0.56 μm, average length L: 0.43 mm, average aspect ratio: 768, decomposition temperature: 400 ° C. or higher, solid content: 20.7%, manufactured by Daisel Finechem Co., Ltd. , Product name: Tiara, Product number: KY400S) 19 parts by weight of water was added to 1 part by weight, and the mixture was stirred at 2000 rpm for 5 minutes using a rotating revolution stirrer. Further, the treatment was performed using a high-pressure homogenizer (50 MPa, 30 passes) to obtain a 1.0 wt% aramid fiber aqueous dispersion.
 1.0重量%CMC水溶液100重量部、1.0重量%アラミド繊維水分散液(1)300重量部、及び水100重量部を配合し、自転公転撹拌機を用いて3000rpmで30分撹拌することにより分散液(1)を得た。 Mix 100 parts by weight of 1.0% by weight CMC aqueous solution, 300 parts by weight of 1.0% by weight aramid fiber aqueous dispersion (1), and 100 parts by weight of water, and stir at 3000 rpm for 30 minutes using a rotating revolution stirrer. As a result, the dispersion liquid (1) was obtained.
 コロナ放電処理を施した多孔質基材としてのポリエチレン微多孔膜(ダイン値44mN/m、厚さ20μm、透気度235sec/100mL、ダブル・スコープ(株)製)の片面に、分散液(1)を、自動塗工装置(テスター産業(株)製、型番:PI-1210)を用いて、240mm/secの速度で塗布し(塗布厚み:250μm)、次に60℃において20分間乾燥して不織布である耐熱層を形成して、積層体(多孔質基材層/耐熱層)であるセパレータを得た。総厚み:25μm、耐熱層の厚み:5μm、耐熱層の坪量:1.80g/m2であった。 A dispersion liquid (1) on one side of a polyethylene microporous film (dyne value 44 mN / m, thickness 20 μm, air permeability 235 sec / 100 mL, manufactured by Double Scope Co., Ltd.) as a porous substrate subjected to corona discharge treatment. ) Is applied at a rate of 240 mm / sec (coating thickness: 250 μm) using an automatic coating device (manufactured by Tester Sangyo Co., Ltd., model number: PI-1210), and then dried at 60 ° C. for 20 minutes. A heat-resistant layer, which is a non-woven fabric, was formed to obtain a separator, which is a laminated body (porous base material layer / heat-resistant layer). The total thickness was 25 μm, the thickness of the heat-resistant layer was 5 μm, and the basis weight of the heat-resistant layer was 1.80 g / m 2.
 [実施例2]
 ダイン値が異なるコロナ放電処理を施したポリエチレン微多孔膜(ダイン値42mN/m、厚さ20μm、透気度235sec/100mL、ダブル・スコープ(株)製)を用いた以外は実施例1と同様にして、セパレータを得た。総厚み:25μm、耐熱層の厚み:5μm、耐熱層の坪量:1.80g/m2であった。
[Example 2]
Same as Example 1 except that a polyethylene microporous membrane (dyne value 42 mN / m, thickness 20 μm, air permeability 235 sec / 100 mL, manufactured by Double Scope Co., Ltd.) subjected to corona discharge treatment having different dyne values was used. And obtained a separator. The total thickness was 25 μm, the thickness of the heat-resistant layer was 5 μm, and the basis weight of the heat-resistant layer was 1.80 g / m 2.
 [実施例3]
 オゾン放電処理を施したポリエチレン微多孔膜(ダイン値44mN/m、厚さ20μm、透気度235sec/100mL、ダブル・スコープ(株)製)を用いた以外は実施例1と同様にして、セパレータを得た。総厚み:25μm、耐熱層の厚み:5μm、耐熱層の坪量:1.80g/m2であった。
[Example 3]
Separator in the same manner as in Example 1 except that a polyethylene microporous membrane (dyne value 44 mN / m, thickness 20 μm, air permeability 235 sec / 100 mL, manufactured by Double Scope Co., Ltd.) subjected to ozone discharge treatment was used. Got The total thickness was 25 μm, the thickness of the heat-resistant layer was 5 μm, and the basis weight of the heat-resistant layer was 1.80 g / m 2.
 [実施例4]
 コロナ放電処理を施した多孔質基材としてのポリエチレン微多孔膜(ダイン値46mN/m、厚さ20μm、透気度235sec/100mL、ダブル・スコープ(株)製)の一方の面に、分散液(1)を、自動塗工装置(テスター産業(株)製、型番:PI-1210)を用いて、240mm/secの速度で塗布し(塗布厚み:250μm)、次に、ヘキサンを含ませた紙を他方の面にあて、ヘキサンを含ませた紙をあてたまま、60℃において20分間乾燥して不織布である耐熱層を形成して、積層体(多孔質基材層/耐熱層)であるセパレータを得た。総厚み:25μm、耐熱層の厚み:5μm、耐熱層の坪量:1.80g/m2であった。
[Example 4]
Dispersion liquid on one surface of a polyethylene microporous film (dyne value 46 mN / m, thickness 20 μm, air permeability 235 sec / 100 mL, manufactured by Double Scope Co., Ltd.) as a porous substrate subjected to corona discharge treatment. (1) was applied at a rate of 240 mm / sec (coating thickness: 250 μm) using an automatic coating device (manufactured by Tester Sangyo Co., Ltd., model number: PI-1210), and then hexane was added. A heat-resistant layer, which is a non-woven fabric, is formed by applying paper to the other surface and drying at 60 ° C. for 20 minutes with the paper soaked in hexane, and then using a laminate (porous base material layer / heat-resistant layer). Obtained a separator. The total thickness was 25 μm, the thickness of the heat-resistant layer was 5 μm, and the basis weight of the heat-resistant layer was 1.80 g / m 2.
 [実施例5]
 コロナ放電処理を施した多孔質基材としてのポリエチレン微多孔膜(ダイン値46mN/m、厚さ20μm、透気度235sec/100mL、ダブル・スコープ(株)製)の一方の面に、分散液(1)を、自動塗工装置(テスター産業(株)製、型番:PI-1210)を用いて、240mm/secの速度で塗布し(塗布厚み:250μm)、次に、流動パラフィンを含ませた紙を他方の面にあて、流動パラフィンを含ませた紙をあてたまま、60℃において20分間乾燥し、不織布である耐熱層を形成した。さらに、積層体(多孔質基材層/耐熱層)をヘキサンにより洗浄し、60℃において5分間乾燥してセパレータを得た。総厚み:25μm、耐熱層の厚み:5μm、耐熱層の坪量:1.80g/m2であった。
[Example 5]
Dispersion liquid on one surface of a polyethylene microporous film (dyne value 46 mN / m, thickness 20 μm, air permeability 235 sec / 100 mL, manufactured by Double Scope Co., Ltd.) as a porous substrate subjected to corona discharge treatment. (1) is applied at a rate of 240 mm / sec using an automatic coating device (manufactured by Tester Sangyo Co., Ltd., model number: PI-1210) (coating thickness: 250 μm), and then liquid paraffin is added. A heat-resistant layer, which is a non-woven fabric, was formed by applying the paper to the other surface and drying at 60 ° C. for 20 minutes while applying the paper containing liquid paraffin. Further, the laminate (porous base material layer / heat-resistant layer) was washed with hexane and dried at 60 ° C. for 5 minutes to obtain a separator. The total thickness was 25 μm, the thickness of the heat-resistant layer was 5 μm, and the basis weight of the heat-resistant layer was 1.80 g / m 2.
 [実施例6]
 コロナ放電処理を施した多孔質基材としてのポリエチレン微多孔膜(ダイン値46mN/m、厚さ20μm、透気度235sec/100mL、ダブル・スコープ(株)製)の一方の面に、微粘着フィルム(パナック(株)製、TS25B)を付着させてから、他方の面に分散液(1)を、自動塗工装置(テスター産業(株)製、型番:PI-1210)を用いて、240mm/secの速度で塗布し(塗布厚み:250μm)、60℃において20分間乾燥して不織布である耐熱層を形成し、微粘着フィルムを剥離してセパレータを得た。総厚み:25μm、耐熱層の厚み:5μm、耐熱層の坪量:1.80g/m2であった。
[Example 6]
Slightly adhered to one surface of a polyethylene microporous film (dyne value 46 mN / m, thickness 20 μm, air permeability 235 sec / 100 mL, manufactured by Double Scope Co., Ltd.) as a porous substrate subjected to corona discharge treatment. After adhering the film (manufactured by Panac Co., Ltd., TS25B), apply the dispersion liquid (1) to the other surface using an automatic coating device (manufactured by Tester Sangyo Co., Ltd., model number: PI-1210), 240 mm. It was applied at a rate of / sec (coating thickness: 250 μm) and dried at 60 ° C. for 20 minutes to form a heat-resistant layer which is a non-woven fabric, and the slightly adhesive film was peeled off to obtain a separator. The total thickness was 25 μm, the thickness of the heat-resistant layer was 5 μm, and the basis weight of the heat-resistant layer was 1.80 g / m 2.
 [比較例1]
 コロナ放電処理を施した多孔質基材としてのポリエチレン微多孔膜(ダイン値46mN/m、厚さ20μm、透気度235sec/100mL、ダブル・スコープ(株)製)を用いた以外は実施例1と同様にして、セパレータを得た。総厚み:25μm、耐熱層の厚み:5μm、耐熱層の坪量:1.80g/m2であった。
[Comparative Example 1]
Example 1 except that a polyethylene microporous membrane (dyne value 46 mN / m, thickness 20 μm, air permeability 235 sec / 100 mL, manufactured by Double Scope Co., Ltd.) was used as a porous substrate subjected to corona discharge treatment. In the same manner as above, a separator was obtained. The total thickness was 25 μm, the thickness of the heat-resistant layer was 5 μm, and the basis weight of the heat-resistant layer was 1.80 g / m 2.
 [比較例2]
 コロナ放電処理を施した多孔質基材としてのポリエチレン微多孔膜(ダイン値46mN/m、厚さ20μm、透気度235sec/100mL、ダブル・スコープ(株)製)のみ(耐熱層を形成せず)をセパレータとした。
[Comparative Example 2]
Only polyethylene microporous membrane (dyne value 46 mN / m, thickness 20 μm, air permeability 235 sec / 100 mL, manufactured by Double Scope Co., Ltd.) as a porous substrate subjected to corona discharge treatment (without forming a heat resistant layer) ) Was used as a separator.
 実施例及び比較例で得られたセパレータについて、セパレータの透気度、耐熱層(B)の坪量を以下の方法により測定した。 For the separators obtained in Examples and Comparative Examples, the air permeability of the separator and the basis weight of the heat-resistant layer (B) were measured by the following methods.
 (透気度試験)
 透気度は、テスター産業(株)製のガーレー式デンソメーターB型を用い、JIS P8117に準じて測定した。秒数はデジタルオートカウンターで測定した。透気度(ガーレー値)の値が小さいほど空気の透過性が高いことを意味する。
(Air permeability test)
The air permeability was measured according to JIS P8117 using a Garley type densometer B type manufactured by Tester Sangyo Co., Ltd. The number of seconds was measured with a digital auto counter. The smaller the value of air permeability (Garley value), the higher the air permeability.
 (耐熱層(B)の坪量)
 坪量は、JIS P8124に準じて測定した。
(Basis weight of heat resistant layer (B))
The basis weight was measured according to JIS P8124.
 上記結果を下記表にまとめて示す。 The above results are summarized in the table below.
Figure JPOXMLDOC01-appb-T000009
Figure JPOXMLDOC01-appb-T000009
 以下、本開示に係る発明のバリエーションを記載する。
[付記1]多孔質基材層(A)と、融点又は分解温度が200℃以上である微小繊維及びバインダを含む不織布からなる耐熱層(B)とを含み、下記式(a)、(b)の少なくとも一方を満たす、二次電池用セパレータ。
(Y-X)/Z < 12   (a)
(Y-X) < 60     (b)
X:多孔質基材(A)の透気度(sec/100mL)
Y:セパレータの透気度(sec/100mL)
Z:耐熱層(B)の厚み(μm)
[付記2](Y-X)/Zに係る値が0~10である、付記1に記載の二次電池用セパレータ。
[付記3](Y-X)に係る値が0~40である、付記1又は2に記載の二次電池用セパレータ。
[付記4]前記セパレータの透気度が100~650sec/100mLである、付記1~3の何れか1つに記載の二次電池用セパレータ。
[付記5]前記セパレータの透気度が100~350sec/100mLである、付記1~3の何れか1つに記載の二次電池用セパレータ。
[付記6]多孔質基材層(A)の有する空隙の大きさが0.01~1μmである、付記1~5の何れか1つに記載の二次電池用セパレータ。
[付記7]多孔質基材層(A)の有する空隙の大きさが0.02~0.06μmである、付記1~5の何れか1つに記載の二次電池用セパレータ。
[付記8]多孔質基材層(A)の空隙率が20~70体積%である、付記1~7の何れか1つに記載の二次電池用セパレータ。
[付記9]多孔質基材層(A)の空隙率が30~60体積%である、付記1~7の何れか1つに記載の二次電池用セパレータ。
[付記10]多孔質基材層(A)の透気度が100~600sec/100mLである、付記1~9の何れか1つに記載の二次電池用セパレータ。
[付記11]多孔質基材層(A)の透気度が100~350sec/100mLである、付記1~9の何れか1つに記載の二次電池用セパレータ。
[付記12]多孔質基材層(A)の材質がポリオレフィン、ポリエステル樹脂又は脂肪族ポリアミドである、付記1~11の何れか1つに記載の二次電池用セパレータ。
[付記13]多孔質基材層(A)の材質がポリエチレンである、付記1~11の何れか1つに記載の二次電池用セパレータ。
[付記14]多孔質基材(A)の厚みが5~40μmである、付記1~13の何れか1つに記載の二次電池用セパレータ。
[付記15]多孔質基材(A)の厚みが10~25μmである、付記1~13の何れか1つに記載の二次電池用セパレータ。
[付記16]前記微小繊維の融点又は分解温度が300~500℃である、付記1~15の何れか1つに記載の二次電池用セパレータ。
[付記17]前記微小繊維の平均アスペクト比(平均長さ/平均太さ)が10~2000である、付記1~16の何れか1つに記載の二次電池用セパレータ。
[付記18]前記微小繊維の平均アスペクト比(平均長さ/平均太さ)が800~1000である、付記1~16の何れか1つに記載の二次電池用セパレータ。
[付記19]前記微小繊維が、フッ素繊維、ガラス繊維、炭素繊維、ポリパラフェニレンベンズオキサゾール繊維、ポリエーテルエーテルケトン繊維及び液晶ポリマー繊維からなる群から選ばれる少なくとも1種である、付記1~18の何れか1つに記載の二次電池用セパレータ。
[付記20]前記微小繊維がアラミド繊維である、付記1~18の何れか1つに記載の二次電池用セパレータ。
[付記21]前記バインダの融点又は分解温度が160~400℃である、付記1~20の何れか1つに記載の二次電池用セパレータ。
[付記22]前記バインダの融点又は分解温度が200~400℃である、付記1~20の何れか1つに記載の二次電池用セパレータ。
[付記23]前記バインダの、1重量%水溶液の粘度(25℃、60回転における)が100~5000mPa・sである、付記1~22の何れか1つに記載の二次電池用セパレータ。
[付記24]前記バインダの、1重量%水溶液の粘度(25℃、60回転における)が1000~2000mPa・sである、付記1~22の何れか1つに記載の二次電池用セパレータ。
[付記25]前記バインダが、フッ素系バインダ、ポリエステル系バインダ、エポキシ系バインダ、アクリル系バインダ、ビニルエーテル系バインダ及び水系バインダからなる群から選ばれる少なくとも1種である、付記1~24の何れか1つに記載の二次電池用セパレータ。
[付記26]前記バインダが水系バインダである、付記1~24の何れか1つに記載の二次電池用セパレータ。
[付記27]前記バインダが、多糖類誘導体(1)、下記式(2)で表される構成単位を有する化合物、及び下記式(3)で表される構成単位を有する化合物から選択される少なくとも1種である、付記26に記載の二次電池用セパレータ。
Figure JPOXMLDOC01-appb-C000010
(式中、Rは水酸基、カルボキシル基、フェニル基、N-置換又は無置換カルバモイル基、又は2-オキソ-1-ピロリジニル基を示す)
Figure JPOXMLDOC01-appb-C000011
(式中、nは2以上の整数を示し、Lはエーテル結合又は(-NH-)基を示す)
[付記28]前記バインダが、多糖類誘導体(1)であって、セルロース、デンプン、グリコーゲン、及びこれらの誘導体から選択される少なくとも1種である、付記27に記載の二次電池用セパレータ。
[付記29]前記バインダが、多糖類誘導体(1)であって、下記式(1-1)で表される構成単位を有するセルロース又はその誘導体である付記27に記載の二次電池用セパレータ。
Figure JPOXMLDOC01-appb-C000012
(式中、R1~R3は、同一又は異なって、水素原子、ヒドロキシル基又はカルボキシル基を有する炭素数1~5のアルキル基を示す。尚、前記ヒドロキシル基及びカルボキシル基はアルカリ金属と塩を形成していてもよい。)
[付記30]前記バインダが、ヒドロキシエチルセルロース、ヒドロキシプロピルセルロース、カルボキシメチルセルロース及びこれらのアルカリ金属塩から選択される少なくとも1種である、付記26に記載の二次電池用セパレータ。
[付記31]前記微小繊維の平均太さが0.01~10μmである、付記1~30の何れか1つに記載の二次電池用セパレータ。
[付記32]前記微小繊維の平均太さが0.05~0.5μmである、付記1~30の何れか1つに記載の二次電池用セパレータ。
[付記33]前記微小繊維の平均長さが0.01~1mmである、付記1~32の何れか1つに記載の二次電池用セパレータ。
[付記34]前記微小繊維の平均長さが0.07~0.4mmである、付記1~32の何れか1つに記載の二次電池用セパレータ。
[付記35]前記微小繊維の平均太さが0.01~10μm、平均長さが0.01~2mmである、付記1~30の何れか1つに記載の二次電池用セパレータ。
[付記36]前記微小繊維の平均太さが0.05~0.5μm、平均長さが0.07~0.4mmである、付記1~30の何れか1つに記載の二次電池用セパレータ。
[付記37]耐熱層(B)の厚みが0.5~20μmである、付記1~36の何れか1つに記載の二次電池用セパレータ。
[付記38]耐熱層(B)の厚みが3~5μmである、付記1~36の何れか1つに記載の二次電池用セパレータ。
[付記39]前記二次電池用セパレータの総厚みが10~50μmである、付記1~38の何れか1つに記載の二次電池用セパレータ。
[付記40]前記二次電池用セパレータの総厚みが12~30μmである、付記1~38の何れか1つに記載の二次電池用セパレータ。
[付記41]耐熱層(B)の厚みが0.5~20μmであり、二次電池用セパレータの総厚みが10~50μmである、付記1~36の何れか1つに記載の二次電池用セパレータ。
[付記42]耐熱層(B)の厚みが3~5μmであり、二次電池用セパレータの総厚みが12~30μmである、付記1~36の何れか1つに記載の二次電池用セパレータ。
[付記43]耐熱層(B)の坪量が10g/m2以下である、付記1~42の何れか1つに記載の二次電池用セパレータ。
[付記44]耐熱層(B)の坪量が1~5g/m2である、付記1~42の何れか1つに記載の二次電池用セパレータ。
[付記45]耐熱層(B)の空隙率が30~60体積%である付記1~44の何れか1つに記載の二次電池用セパレータ。
[付記46]耐熱層(B)の空隙率が35~55体積%である付記1~44の何れか1つに記載の二次電池用セパレータ。
[付記47]耐熱層(B)の透気度が1~500sec/100mLである、付記1~46の何れか1つに記載の二次電池用セパレータ。
[付記48]耐熱層(B)の透気度が1~70sec/100mLである、付記1~46の何れか1つに記載の二次電池用セパレータ。
[付記49]多孔質基材層(A)の一方の面に離型フィルムを貼着し、前記多孔質基材層(A)の他方の面に、微小繊維とバインダを含む分散液を塗布し、前記分散液中の分散媒を揮発させてから、前記離型フィルムを多孔質基材層(A)から剥離させることにより、付記1~48の何れか1つに記載の二次電池用セパレータを得る、二次電池用セパレータの製造方法。
[付記50]多孔質基材層(A)の表面を表面処理によりダイン値40~45mN/mに調製してから、前記表面に微小繊維とバインダを含む分散液を塗布し、前記分散液中の分散媒を揮発させることにより、付記1~48の何れか1つに記載の二次電池用セパレータを得る、二次電池用セパレータの製造方法。
[付記51]前記ダイン値が42~43mN/mである、付記50に記載の二次電池用セパレータの製造方法。
[付記52]微小繊維とバインダを含む分散液の塗布を多孔質基材層(A)の片面又は両面に対して行う、付記50又は51に記載の二次電池用セパレータの製造方法。
[付記53]多孔質基材層(A)の一方の面に、微小繊維とバインダを含む分散液を塗布し、前記多孔質基材層(A)の他方の面から、低極性又は無極性の有機溶媒を浸透させてから、前記分散液中の分散媒を揮発させることにより、付記1~48の何れか1つに記載の二次電池用セパレータを得る、二次電池用セパレータの製造方法。
[付記54]前記低極性又は無極性の有機溶媒が、脂肪族炭化水素、脂環式炭化水素、脂肪族不飽和炭化水素、芳香族炭化水素、ハロゲン化炭化水素、ハロゲン化芳香族炭化水素、エステル系溶媒及びパラフィン系炭化水素から選択される少なくとも1種である、付記53に記載の二次電池用セパレータの製造方法。
[付記55]前記低極性又は無極性の有機溶媒が、流動パラフィン及び/又はヘキサンである、付記53に記載の二次電池用セパレータの製造方法。
[付記56]前記分散液中における、微小繊維とバインダの含有割合が、微小繊維10重量部に対してバインダ1~20重量部である、付記49~55の何れか1つに記載の二次電池用セパレータの製造方法。
[付記57]前記分散液中における微小繊維とバインダの合計含有量が0.5~10重量%である、付記49~56の何れか1つに記載の二次電池用セパレータの製造方法。
[付記58]前記分散液中における微小繊維とバインダの合計含有量が0.7~3重量%である、付記49~56の何れか1つに記載の二次電池用セパレータの製造方法。
[付記59]前記分散液中における、微小繊維、バインダ及び分散媒の合計含有量の占める割合が50重量%以上である、付記49~58の何れか1つに記載の二次電池用セパレータの製造方法。
[付記60]前記分散液中における、微小繊維、バインダ及び分散媒の合計含有量の占める割合が90重量%以上である、付記49~58の何れか1つに記載の二次電池用セパレータの製造方法。
[付記61]前記分散媒が水を含む、付記49~60の何れか1つに記載の二次電池用セパレータの製造方法。
[付記62]前記分散媒が、分散媒全量中2重量%以下の有機溶媒を含む、付記61に記載の二次電池用セパレータの製造方法。
[付記63]付記1~48の何れか1つに記載の二次電池用セパレータを備えた二次電池。
[付記64]付記49~62の何れか1つに記載の二次電池用セパレータの製造方法により二次電池用セパレータを得て、得られた二次電池用セパレータを用いて二次電池を製造する、二次電池の製造方法。
[付記65]多孔質基材層(A)と、融点又は分解温度が200℃以上である微小繊維及びバインダを含む不織布からなる耐熱層(B)とを含み、下記式(a)、(b)の少なくとも一方を満たす積層体の、二次電池用セパレータとしての用途。
(Y-X)/Z < 12   (a)
(Y-X) < 60     (b)
X:多孔質基材(A)の透気度(sec/100mL)
Y:セパレータの透気度(sec/100mL)
Z:耐熱層(B)の厚み(μm)
Hereinafter, variations of the invention according to the present disclosure will be described.
[Appendix 1] A porous base material layer (A) and a heat-resistant layer (B) made of a non-woven fabric containing microfibers having a melting point or a decomposition temperature of 200 ° C. or higher and a binder are included, and the following formulas (a) and (b) are included. ), A separator for a secondary battery that satisfies at least one of them.
(YX) / Z <12 (a)
(YX) <60 (b)
X: Air permeability of the porous substrate (A) (sec / 100 mL)
Y: Air permeability of separator (sec / 100mL)
Z: Thickness (μm) of heat-resistant layer (B)
[Appendix 2] The separator for a secondary battery according to Annex 1, wherein the value according to (YX) / Z is 0 to 10.
[Supplementary Note 3] The separator for a secondary battery according to Supplementary note 1 or 2, wherein the value according to (YX) is 0 to 40.
[Appendix 4] The separator for a secondary battery according to any one of the appendices 1 to 3, wherein the separator has an air permeability of 100 to 650 sec / 100 mL.
[Appendix 5] The separator for a secondary battery according to any one of the appendices 1 to 3, wherein the separator has an air permeability of 100 to 350 sec / 100 mL.
[Appendix 6] The separator for a secondary battery according to any one of the appendices 1 to 5, wherein the size of the voids of the porous substrate layer (A) is 0.01 to 1 μm.
[Appendix 7] The separator for a secondary battery according to any one of the appendices 1 to 5, wherein the size of the voids of the porous substrate layer (A) is 0.02 to 0.06 μm.
[Appendix 8] The separator for a secondary battery according to any one of the appendices 1 to 7, wherein the porous base material layer (A) has a porosity of 20 to 70% by volume.
[Appendix 9] The separator for a secondary battery according to any one of the appendices 1 to 7, wherein the porous base material layer (A) has a porosity of 30 to 60% by volume.
[Appendix 10] The separator for a secondary battery according to any one of the appendices 1 to 9, wherein the porous substrate layer (A) has an air permeability of 100 to 600 sec / 100 mL.
[Appendix 11] The separator for a secondary battery according to any one of the appendices 1 to 9, wherein the porous substrate layer (A) has an air permeability of 100 to 350 sec / 100 mL.
[Supplementary Note 12] The separator for a secondary battery according to any one of Supplementary note 1 to 11, wherein the material of the porous base material layer (A) is polyolefin, polyester resin or aliphatic polyamide.
[Supplementary Note 13] The separator for a secondary battery according to any one of Supplementary note 1 to 11, wherein the material of the porous base material layer (A) is polyethylene.
[Appendix 14] The separator for a secondary battery according to any one of the appendices 1 to 13, wherein the porous substrate (A) has a thickness of 5 to 40 μm.
[Appendix 15] The separator for a secondary battery according to any one of the appendices 1 to 13, wherein the porous substrate (A) has a thickness of 10 to 25 μm.
[Appendix 16] The separator for a secondary battery according to any one of the appendices 1 to 15, wherein the melting point or decomposition temperature of the microfiber is 300 to 500 ° C.
[Appendix 17] The separator for a secondary battery according to any one of the appendices 1 to 16, wherein the fine fibers have an average aspect ratio (average length / average thickness) of 10 to 2000.
[Appendix 18] The separator for a secondary battery according to any one of the appendices 1 to 16, wherein the average aspect ratio (average length / average thickness) of the fine fibers is 800 to 1000.
[Appendix 19] The microfiber is at least one selected from the group consisting of fluorine fiber, glass fiber, carbon fiber, polyparaphenylene benzoxazole fiber, polyether ether ketone fiber and liquid crystal polymer fiber, Appendix 1 to 18. The separator for a secondary battery according to any one of the above.
[Supplementary Note 20] The separator for a secondary battery according to any one of Supplementary note 1 to 18, wherein the microfibers are aramid fibers.
[Appendix 21] The separator for a secondary battery according to any one of the appendices 1 to 20, wherein the binder has a melting point or a decomposition temperature of 160 to 400 ° C.
[Appendix 22] The separator for a secondary battery according to any one of the appendices 1 to 20, wherein the binder has a melting point or a decomposition temperature of 200 to 400 ° C.
[Supplementary Note 23] The separator for a secondary battery according to any one of Supplementary note 1 to 22, wherein the viscosity of the 1 wt% aqueous solution of the binder (at 25 ° C. and 60 rotations) is 100 to 5000 mPa · s.
[Supplementary Note 24] The separator for a secondary battery according to any one of Supplementary note 1 to 22, wherein the viscosity of the 1 wt% aqueous solution of the binder (at 25 ° C. and 60 rotations) is 1000 to 2000 mPa · s.
[Appendix 25] The binder is at least one selected from the group consisting of a fluorine-based binder, a polyester-based binder, an epoxy-based binder, an acrylic-based binder, a vinyl ether-based binder, and a water-based binder, any one of Supplementary note 1 to 24. The separator for the secondary battery described in 1.
[Supplementary Note 26] The separator for a secondary battery according to any one of Supplementary note 1 to 24, wherein the binder is a water-based binder.
[Appendix 27] At least the binder is selected from a polysaccharide derivative (1), a compound having a structural unit represented by the following formula (2), and a compound having a structural unit represented by the following formula (3). The separator for a secondary battery according to Appendix 26, which is one type.
Figure JPOXMLDOC01-appb-C000010
(In the formula, R represents a hydroxyl group, a carboxyl group, a phenyl group, an N-substituted or unsubstituted carbamoyl group, or a 2-oxo-1-pyrrolidinyl group).
Figure JPOXMLDOC01-appb-C000011
(In the formula, n indicates an integer of 2 or more, and L indicates an ether bond or a (-NH-) group).
[Appendix 28] The separator for a secondary battery according to Annex 27, wherein the binder is a polysaccharide derivative (1) and is at least one selected from cellulose, starch, glycogen, and derivatives thereof.
[Supplementary Note 29] The separator for a secondary battery according to Supplementary note 27, wherein the binder is a polysaccharide derivative (1) and is cellulose or a derivative thereof having a structural unit represented by the following formula (1-1).
Figure JPOXMLDOC01-appb-C000012
(In the formula, R 1 to R 3 represent the same or different alkyl groups having hydrogen atoms, hydroxyl groups or carboxyl groups and having 1 to 5 carbon atoms. The hydroxyl groups and carboxyl groups are alkali metals and salts. May be formed.)
[Appendix 30] The separator for a secondary battery according to Annex 26, wherein the binder is at least one selected from hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose and alkali metal salts thereof.
[Appendix 31] The separator for a secondary battery according to any one of the appendices 1 to 30, wherein the fine fibers have an average thickness of 0.01 to 10 μm.
[Appendix 32] The separator for a secondary battery according to any one of the appendices 1 to 30, wherein the fine fibers have an average thickness of 0.05 to 0.5 μm.
[Appendix 33] The separator for a secondary battery according to any one of the appendices 1 to 32, wherein the fine fibers have an average length of 0.01 to 1 mm.
[Appendix 34] The separator for a secondary battery according to any one of the appendices 1 to 32, wherein the fine fibers have an average length of 0.07 to 0.4 mm.
[Appendix 35] The separator for a secondary battery according to any one of the appendices 1 to 30, wherein the fine fibers have an average thickness of 0.01 to 10 μm and an average length of 0.01 to 2 mm.
[Appendix 36] The secondary battery according to any one of the appendices 1 to 30, wherein the fine fibers have an average thickness of 0.05 to 0.5 μm and an average length of 0.07 to 0.4 mm. Separator.
[Appendix 37] The separator for a secondary battery according to any one of the appendices 1 to 36, wherein the heat-resistant layer (B) has a thickness of 0.5 to 20 μm.
[Appendix 38] The separator for a secondary battery according to any one of the appendices 1 to 36, wherein the heat-resistant layer (B) has a thickness of 3 to 5 μm.
[Appendix 39] The separator for a secondary battery according to any one of the appendices 1 to 38, wherein the total thickness of the separator for the secondary battery is 10 to 50 μm.
[Appendix 40] The separator for a secondary battery according to any one of the appendices 1 to 38, wherein the total thickness of the separator for the secondary battery is 12 to 30 μm.
[Supplementary Note 41] The secondary battery according to any one of Supplementary note 1 to 36, wherein the heat-resistant layer (B) has a thickness of 0.5 to 20 μm, and the total thickness of the separator for a secondary battery is 10 to 50 μm. Separator for.
[Appendix 42] The separator for a secondary battery according to any one of the appendices 1 to 36, wherein the heat-resistant layer (B) has a thickness of 3 to 5 μm and the total thickness of the separator for a secondary battery is 12 to 30 μm. ..
[Supplementary Note 43] The separator for a secondary battery according to any one of Supplementary note 1 to 42, wherein the heat-resistant layer (B) has a basis weight of 10 g / m 2 or less.
[Appendix 44] The separator for a secondary battery according to any one of the appendices 1 to 42, wherein the heat-resistant layer (B) has a basis weight of 1 to 5 g / m 2.
[Appendix 45] The separator for a secondary battery according to any one of the appendices 1 to 44, wherein the heat-resistant layer (B) has a porosity of 30 to 60% by volume.
[Supplementary Note 46] The separator for a secondary battery according to any one of Supplementary note 1 to 44, wherein the heat-resistant layer (B) has a porosity of 35 to 55% by volume.
[Appendix 47] The separator for a secondary battery according to any one of the appendices 1 to 46, wherein the heat-resistant layer (B) has an air permeability of 1 to 500 sec / 100 mL.
[Appendix 48] The separator for a secondary battery according to any one of the appendices 1 to 46, wherein the heat-resistant layer (B) has an air permeability of 1 to 70 sec / 100 mL.
[Appendix 49] A release film is attached to one surface of the porous substrate layer (A), and a dispersion liquid containing fine fibers and a binder is applied to the other surface of the porous substrate layer (A). Then, after volatilizing the dispersion medium in the dispersion liquid, the release film is peeled off from the porous base material layer (A), whereby the secondary battery according to any one of Supplementary note 1 to 48 is used. A method for manufacturing a separator for a secondary battery to obtain a separator.
[Appendix 50] After preparing the surface of the porous base material layer (A) to a dyne value of 40 to 45 mN / m by surface treatment, a dispersion liquid containing fine fibers and a binder is applied to the surface, and the dispersion liquid contains the fine fibers and a binder. A method for manufacturing a separator for a secondary battery, wherein the separator for a secondary battery according to any one of Supplementary note 1 to 48 is obtained by volatilizing the dispersion medium of the above.
[Supplementary Note 51] The method for manufacturing a separator for a secondary battery according to Supplementary Note 50, wherein the dyne value is 42 to 43 mN / m.
[Appendix 52] The method for producing a separator for a secondary battery according to Appendix 50 or 51, wherein the dispersion liquid containing the fine fibers and the binder is applied to one side or both sides of the porous base material layer (A).
[Appendix 53] A dispersion liquid containing fine fibers and a binder is applied to one surface of the porous substrate layer (A), and low polarity or non-polarity is applied from the other surface of the porous substrate layer (A). A method for producing a separator for a secondary battery, which comprises permeating the organic solvent of the above and then volatilizing the dispersion medium in the dispersion liquid to obtain a separator for a secondary battery according to any one of Supplementary note 1 to 48. ..
[Appendix 54] The low-polarity or non-polar organic solvent is an aliphatic hydrocarbon, an alicyclic hydrocarbon, an aliphatic unsaturated hydrocarbon, an aromatic hydrocarbon, a halogenated hydrocarbon, a halogenated aromatic hydrocarbon, and the like. The method for producing a separator for a secondary battery according to Appendix 53, which is at least one selected from an ester-based solvent and a paraffin-based hydrocarbon.
[Appendix 55] The method for producing a separator for a secondary battery according to Appendix 53, wherein the low-polarity or non-polar organic solvent is liquid paraffin and / or hexane.
[Appendix 56] The secondary according to any one of the appendices 49 to 55, wherein the content ratio of the fine fibers and the binder in the dispersion liquid is 1 to 20 parts by weight with respect to 10 parts by weight of the fine fibers. Manufacturing method of battery separator.
[Appendix 57] The method for producing a separator for a secondary battery according to any one of the appendices 49 to 56, wherein the total content of the fine fibers and the binder in the dispersion is 0.5 to 10% by weight.
[Appendix 58] The method for producing a separator for a secondary battery according to any one of the appendices 49 to 56, wherein the total content of the fine fibers and the binder in the dispersion is 0.7 to 3% by weight.
[Supplementary Note 59] The separator for a secondary battery according to any one of Supplementary note 49 to 58, wherein the ratio of the total content of the fine fibers, the binder and the dispersion medium in the dispersion liquid is 50% by weight or more. Production method.
[Supplementary Note 60] The separator for a secondary battery according to any one of Supplementary note 49 to 58, wherein the ratio of the total content of the fine fibers, the binder and the dispersion medium in the dispersion liquid is 90% by weight or more. Production method.
[Supplementary Note 61] The method for producing a separator for a secondary battery according to any one of Supplementary note 49 to 60, wherein the dispersion medium contains water.
[Appendix 62] The method for producing a separator for a secondary battery according to Appendix 61, wherein the dispersion medium contains 2% by weight or less of an organic solvent in the total amount of the dispersion medium.
[Supplementary Note 63] A secondary battery provided with the secondary battery separator according to any one of Supplementary note 1 to 48.
[Appendix 64] A secondary battery separator is obtained by the method for manufacturing a secondary battery separator according to any one of the appendices 49 to 62, and a secondary battery is manufactured using the obtained secondary battery separator. How to manufacture a secondary battery.
[Appendix 65] The porous base material layer (A) and the heat-resistant layer (B) made of a non-woven fabric containing microfibers having a melting point or a decomposition temperature of 200 ° C. or higher and a binder are included, and the following formulas (a) and (b) are included. ), A laminate that satisfies at least one of the above, and is used as a separator for a secondary battery.
(YX) / Z <12 (a)
(YX) <60 (b)
X: Air permeability of the porous substrate (A) (sec / 100 mL)
Y: Air permeability of separator (sec / 100mL)
Z: Thickness (μm) of heat-resistant layer (B)
 本開示の二次電池用セパレータは、透気性が低く、且つ透湿性に優れ、また、低温低湿度環境下での透湿性にも優れるので、全熱交換シートとして特に好ましく用いることができる。また、本開示の製造方法により、透過性に優れた二次電池用セパレータを効率的に製造することが可能となる。従って、本開示は、産業上の利用可能性を有する。 The separator for a secondary battery of the present disclosure has low air permeability, is excellent in moisture permeability, and is also excellent in moisture permeability in a low temperature and low humidity environment, so that it can be particularly preferably used as a total heat exchange sheet. Further, according to the manufacturing method of the present disclosure, it becomes possible to efficiently manufacture a separator for a secondary battery having excellent permeability. Therefore, the present disclosure has industrial applicability.

Claims (13)

  1.  多孔質基材層(A)と、融点又は分解温度が200℃以上である微小繊維及びバインダを含む不織布からなる耐熱層(B)とを含み、下記式(a)、(b)の少なくとも一方を満たす、二次電池用セパレータ。
     (Y-X)/Z < 12   (a)
     (Y-X) < 60     (b)
    X:多孔質基材(A)の透気度(sec/100mL)
    Y:セパレータの透気度(sec/100mL)
    Z:耐熱層(B)の厚み(μm)
    It contains a porous base material layer (A) and a heat-resistant layer (B) made of a non-woven fabric containing fine fibers and a binder having a melting point or decomposition temperature of 200 ° C. or higher, and at least one of the following formulas (a) and (b). A separator for secondary batteries that meets the requirements.
    (YX) / Z <12 (a)
    (YX) <60 (b)
    X: Air permeability of the porous substrate (A) (sec / 100 mL)
    Y: Air permeability of separator (sec / 100mL)
    Z: Thickness (μm) of heat-resistant layer (B)
  2.  微小繊維がアラミド繊維である請求項1に記載の二次電池用セパレータ。 The separator for a secondary battery according to claim 1, wherein the fine fibers are aramid fibers.
  3.  バインダが水系バインダである請求項1又は2に記載の二次電池用セパレータ。 The separator for a secondary battery according to claim 1 or 2, wherein the binder is a water-based binder.
  4.  バインダが、多糖類誘導体(1)、下記式(2)で表される構成単位を有する化合物、及び下記式(3)で表される構成単位を有する化合物から選択される少なくとも1種である請求項1~3の何れか1項に記載の二次電池用セパレータ。
    Figure JPOXMLDOC01-appb-C000001
    (式中、Rは水酸基、カルボキシル基、フェニル基、N-置換又は無置換カルバモイル基、又は2-オキソ-1-ピロリジニル基を示す)
    Figure JPOXMLDOC01-appb-C000002
    (式中、nは2以上の整数を示し、Lはエーテル結合又は(-NH-)基を示す)
    Claims that the binder is at least one selected from a polysaccharide derivative (1), a compound having a structural unit represented by the following formula (2), and a compound having a structural unit represented by the following formula (3). Item 2. The separator for a secondary battery according to any one of Items 1 to 3.
    Figure JPOXMLDOC01-appb-C000001
    (In the formula, R represents a hydroxyl group, a carboxyl group, a phenyl group, an N-substituted or unsubstituted carbamoyl group, or a 2-oxo-1-pyrrolidinyl group).
    Figure JPOXMLDOC01-appb-C000002
    (In the formula, n indicates an integer of 2 or more, and L indicates an ether bond or a (-NH-) group).
  5.  バインダが、セルロース、デンプン、グリコーゲン、及びこれらの誘導体から選択される少なくとも1種である請求項1~3の何れか1項に記載の二次電池用セパレータ。 The separator for a secondary battery according to any one of claims 1 to 3, wherein the binder is at least one selected from cellulose, starch, glycogen, and derivatives thereof.
  6.  微小繊維の平均太さが0.01~10μm、平均長さが0.01~2mmである請求項1~5の何れか1項に記載の二次電池用セパレータ。 The separator for a secondary battery according to any one of claims 1 to 5, wherein the fine fibers have an average thickness of 0.01 to 10 μm and an average length of 0.01 to 2 mm.
  7.  耐熱層(B)の厚みが0.5~20μmであり、二次電池用セパレータの総厚みが10~50μmである請求項1~6の何れか1項に記載の二次電池用セパレータ。 The separator for a secondary battery according to any one of claims 1 to 6, wherein the heat-resistant layer (B) has a thickness of 0.5 to 20 μm, and the total thickness of the separator for a secondary battery is 10 to 50 μm.
  8.  耐熱層(B)の坪量が10g/m2以下である請求項1~7の何れか1項に記載の二次電池用セパレータ。 The separator for a secondary battery according to any one of claims 1 to 7, wherein the heat-resistant layer (B) has a basis weight of 10 g / m 2 or less.
  9.  多孔質基材層(A)の一方の面に離型フィルムを貼着し、前記多孔質基材層(A)の他方の面に、微小繊維とバインダを含む分散液を塗布し、前記分散液中の分散媒を揮発させてから、前記離型フィルムを多孔質基材層(A)から剥離させることにより、請求項1~8の何れか1項に記載の二次電池用セパレータを得る、二次電池用セパレータの製造方法。 A release film is attached to one surface of the porous substrate layer (A), and a dispersion liquid containing fine fibers and a binder is applied to the other surface of the porous substrate layer (A) to disperse the dispersion. The separator for a secondary battery according to any one of claims 1 to 8 is obtained by volatilizing the dispersion medium in the liquid and then peeling the release film from the porous substrate layer (A). , A method for manufacturing a separator for a secondary battery.
  10.  多孔質基材層(A)の表面を表面処理によりダイン値40~45mN/mに調製してから、前記表面に微小繊維とバインダを含む分散液を塗布し、前記分散液中の分散媒を揮発させることにより、請求項1~8の何れか1項に記載の二次電池用セパレータを得る、二次電池用セパレータの製造方法。 After preparing the surface of the porous base material layer (A) to a dyne value of 40 to 45 mN / m by surface treatment, a dispersion liquid containing fine fibers and a binder is applied to the surface, and the dispersion medium in the dispersion liquid is applied. A method for manufacturing a separator for a secondary battery, wherein the separator for a secondary battery according to any one of claims 1 to 8 is obtained by volatilizing the separator.
  11.  多孔質基材層(A)の一方の面に、微小繊維とバインダを含む分散液を塗布し、前記多孔質基材層(A)の他方の面から、低極性又は無極性の有機溶媒を浸透させてから、前記分散液中の分散媒を揮発させることにより、請求項1~8の何れか1項に記載の二次電池用セパレータを得る、二次電池用セパレータの製造方法。 A dispersion liquid containing fine fibers and a binder is applied to one surface of the porous substrate layer (A), and a low-polarity or non-polar organic solvent is applied from the other surface of the porous substrate layer (A). A method for producing a separator for a secondary battery, wherein the separator for a secondary battery according to any one of claims 1 to 8 is obtained by infiltrating and then volatilizing the dispersion medium in the dispersion liquid.
  12.  請求項1~8の何れか1項に記載の二次電池用セパレータを備えた二次電池。 A secondary battery provided with the separator for the secondary battery according to any one of claims 1 to 8.
  13.  請求項9~11の何れか1項に記載の二次電池用セパレータの製造方法により二次電池用セパレータを得て、得られた二次電池用セパレータを用いて二次電池を製造する、二次電池の製造方法。 A secondary battery separator is obtained by the method for manufacturing a secondary battery separator according to any one of claims 9 to 11, and a secondary battery is manufactured using the obtained secondary battery separator. Next battery manufacturing method.
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WO2019130994A1 (en) * 2017-12-27 2019-07-04 帝人株式会社 Separator for non-aqueous secondary batteries, and non-aqueous secondary battery
JP2019149361A (en) * 2018-02-26 2019-09-05 株式会社ダイセル Secondary battery separator

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JP2019149361A (en) * 2018-02-26 2019-09-05 株式会社ダイセル Secondary battery separator

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