WO2018003936A1 - キャパシタ用セパレータ - Google Patents
キャパシタ用セパレータ Download PDFInfo
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- WO2018003936A1 WO2018003936A1 PCT/JP2017/024005 JP2017024005W WO2018003936A1 WO 2018003936 A1 WO2018003936 A1 WO 2018003936A1 JP 2017024005 W JP2017024005 W JP 2017024005W WO 2018003936 A1 WO2018003936 A1 WO 2018003936A1
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- WIPO (PCT)
- Prior art keywords
- fiber
- separator
- polyvinyl alcohol
- fibrillated
- capacitor
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
- H01G11/52—Separators
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
- H01G9/004—Details
- H01G9/02—Diaphragms; Separators
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
- C08L1/02—Cellulose; Modified cellulose
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L29/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal or ketal radical; Compositions of hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Compositions of derivatives of such polymers
- C08L29/02—Homopolymers or copolymers of unsaturated alcohols
- C08L29/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
- H01G11/84—Processes for the manufacture of hybrid or EDL capacitors, or components thereof
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2203/00—Applications
- C08L2203/20—Applications use in electrical or conductive gadgets
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2205/00—Polymer mixtures characterised by other features
- C08L2205/03—Polymer mixtures characterised by other features containing three or more polymers in a blend
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2205/00—Polymer mixtures characterised by other features
- C08L2205/14—Polymer mixtures characterised by other features containing polymeric additives characterised by shape
- C08L2205/16—Fibres; Fibrils
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/13—Energy storage using capacitors
Definitions
- the present invention relates to a capacitor separator and a manufacturing method thereof.
- the electric double layer capacitors are used in various fields, such as memory backup power sources for personal computers and secondary battery auxiliary, because they have a very large capacitance and can be repeatedly used after being charged.
- the electric double layer capacitor is usually composed of positive and negative electrodes, an electrolytic solution, a separator, a current collector plate, and the like, and the separator is used to separate the positive electrode active material and the negative electrode active material.
- Patent Document 1 discloses a separator using a fibrillated product of cellulose fibers.
- Patent Document 2 discloses a separator using rayon which is a recycled fiber.
- capacitor separators are required to be as thin as possible while suppressing short circuits.
- the risk of an internal short circuit between the positive electrode active material and the negative electrode active material is increased, and the mechanical strength is reduced, which may cause problems in the manufacturing process of the separator. Therefore, the amount of binder added may be increased in order to increase the mechanical strength.
- the binder is added excessively, the electrolyte ions in the electrolyte cannot pass well through the separator, which is used for capacitors. This is not preferable because the internal resistance increases.
- Patent Documents 1 and 2 are very useful because they can provide a dense separator having high liquid retention and good electrical characteristics. However, these separators may have insufficient strength when thinned.
- an object of the present invention is to provide a capacitor separator having high strength and low internal resistance when used in a capacitor, and a method for manufacturing the same.
- the present inventor arrived at the present invention as a result of detailed studies on a capacitor separator and a manufacturing method thereof.
- a capacitor separator comprising fibrillated fibers made of only a polyvinyl alcohol resin in an amount of 30% by weight or more based on the total weight of the separator.
- the present invention it is possible to provide a capacitor separator having a high strength and a low internal resistance when used in a capacitor, and a method for manufacturing the same.
- the capacitor separator according to one embodiment of the present invention contains a fibrillated fiber (A) (hereinafter also referred to as “fibrillated PVA fiber (A)”) made of only polyvinyl alcohol, that is, the fibril. It is a separator made by using a modified PVA fiber (A).
- the polyvinyl alcohol contained in the fibrillated PVA fiber (A) is usually 70 mol% or more, preferably 90 mol% or more, more preferably 95 mol%, from the viewpoint of oriented crystallization. More preferably, it is 98 mol% or more, particularly preferably 99 mol% or more, and very preferably 99.8 mol% or more.
- Polyvinyl alcohol is a structural unit derived from other monomers such as ethylene alcohol, itaconic acid, vinylamine, acrylamide, vinyl piperate, maleic anhydride, and sulfonic acid-containing vinyl compounds in addition to vinyl alcohol constituent units.
- the copolymer may be contained at a ratio of 30 mol% or less.
- the saponification degree is preferably 80 mol% or more, and is usually 100 mol% or less.
- the viscosity average degree of polymerization of polyvinyl alcohol is not particularly limited, but is preferably 500 or more, more preferably 1500 or more, from the viewpoint of obtaining high-strength fibrils.
- the upper limit of the viscosity average polymerization degree of polyvinyl alcohol is not specifically limited, For example, it is 4000 or less.
- the polyvinyl alcohol may be acetalized by post-reaction after fiberization.
- the viscosity average polymerization degree of polyvinyl alcohol can be measured according to JIS K 6726.
- the degree of acetalization of polyvinyl alcohol is preferably 3 mol% or more, more preferably 6 mol% or more, still more preferably 10 mol% or more, preferably 40 mol% or less, more preferably 35 mol%.
- it is more preferably 30 mol% or less, particularly preferably 25 mol% or less, particularly preferably 20 mol% or less, for example, 15 mol% or less.
- the fibrillated PVA fiber (A) tends to have a fine structure, and the fiber can be easily refined by mechanical treatment.
- the degree of acetalization is the ratio of the acetal bond generated by the reaction of the acetal compound and the hydroxyl group of polyvinyl alcohol to the vinyl alcohol structural unit, and represents the abundance of the acetal bond in the polyvinyl alcohol fiber.
- the degree of acetalization of polyvinyl alcohol can be calculated using 1 H-NMR or 13 C-NMR.
- the aspect ratio of the fibrillated PVA fiber (A) is preferably 500 or more, more preferably 600 or more, still more preferably 700 or more, particularly preferably 800 or more, particularly preferably 900 or more, and most preferably 1000. Or more, preferably 6000 or less, more preferably 5000 or less, further preferably 4000 or less, particularly preferably 3000 or less, and particularly preferably 2500 or less.
- the aspect ratio of the fibrillated PVA fiber (A) is not less than the above lower limit, the fibrillated PVA fiber (A) is less likely to fall off during papermaking of the separator, and the mechanical strength of the separator can be further improved.
- the aspect ratio of the fibrillated PVA fiber (A) is not more than the above upper limit, excessive entanglement between the fibers can be suppressed, and the separator can be satisfactorily formed.
- the aspect ratio of the fibrillated PVA fiber (A) is, for example, when fibers other than PVA fibers are included, after removing fibers other than PVA fibers by a dissolution method according to the fiber identification method. , Optionally 20 fibrillated PVA fibers are collected, the width and length of each fiber taken out by an optical microscope are measured, the aspect ratio is calculated based on the numerical values, and the average value of the 20 fibers is obtained. Can be measured.
- the CSF (Canadian Standard Freeness) of the fibrillated PVA fiber (A) is preferably 5 to 500 ml, more preferably 10 to 400 ml, still more preferably 50 to 350 ml.
- CSF represents the degree of beating of the fiber.
- the separator itself has a good texture, and a dense and homogeneous separator can be obtained.
- the CSF of the fibrillated PVA fiber (A) is not more than the above upper limit, a separator having higher mechanical strength can be obtained.
- CSF can be measured according to JIS P 8121 “Pulp Freeness Test Method”.
- the shape of the fibrillated PVA fiber (A) is not particularly limited, and examples thereof include fibrous (particularly cotton) and powdery forms. From the viewpoint of obtaining a capacitor separator having higher mechanical strength and lower internal resistance at the same time, the shape of the fibrillated PVA fiber (A) is preferably fibrous, more preferably cotton.
- the fibrillated PVA fiber (A) does not contain a resin other than PVA, but is an inorganic pigment, an organic pigment, a heat deterioration inhibitor, a pH adjuster, and a crosslinking agent as long as the effects of the present invention are not impaired. And additives such as oils.
- the fibrillated PVA fiber (A) is made of only polyvinyl alcohol as a resin.
- the fiber usually contains a cellulose-based fibrillation aid or an acrylonitrile-based fibrillation aid. Due to the presence of the cellulose-based fibrillation aid and the acrylonitrile-based fibrillation aid, the fibrillation property is greatly reduced.
- a PVA-based binder is suitable for improving the mechanical strength.
- a polymer other than PVA the mechanical strength of the separator may be lowered.
- the fibrillated fiber made of only polyvinyl alcohol is used, it is possible to suppress the moisture retention, and to obtain a capacitor separator having high mechanical strength and low internal resistance.
- an organic electrolyte is used as the electrolyte in the capacitor, water becomes an impurity and deteriorates the capacitor performance. The lower the moisture retention, the lower the energy that can be dried.
- the capacitor separator according to one embodiment of the present invention is made of only polyvinyl alcohol, it has a low moisture retention rate and has high heat resistance that can sufficiently withstand drying, so that it can be dried with low energy. is there. Therefore, the separator according to one embodiment of the present invention is suitable as a capacitor separator using an organic electrolyte.
- the capacitor separator is 30% by weight or more, preferably 35% by weight or more, more preferably 40% by weight or more, and further preferably 50% by weight or more of the fibrillated PVA fiber (A) based on the total weight of the separator. And preferably 90% by weight or less, more preferably 80% by weight or less, and still more preferably 70% by weight or less of fibrillated PVA fibers (A).
- the content of the fibrillated PVA fiber (A) in the capacitor separator is equal to or higher than the lower limit, the mechanical strength of the separator can be increased, and problems in manufacturing can be suppressed.
- the content of the fibrillated PVA fiber (A) in the capacitor separator is not more than the above upper limit value, the uniformity of each component in the separator is good, so that unevenness in strength in the separator can be suppressed.
- the method for producing the fibrillated PVA fiber (A) is not particularly limited.
- a fibrillated PVA fiber may be produced by high-pressure jetting a slurry in which polyvinyl alcohol fibers are dispersed, or a suitable fibrillation aid is blended in polyvinyl alcohol and spun. Then, the fibrillated PVA fiber may be produced by dispersing the spun fiber in water and beating it to a predetermined freeness with a paper-making beating machine such as a beater, a disc refiner, or a high-speed beating machine.
- a paper-making beating machine such as a beater, a disc refiner, or a high-speed beating machine.
- an easily fibrillated polyvinyl alcohol fiber containing polyvinyl alcohol and polyalkylene oxide is beaten by using a paper beater such as a beater, a disc refiner, or a high-speed beater.
- a paper beater such as a beater, a disc refiner, or a high-speed beater.
- the fibrillated PVA fiber (A) having relatively long fibers, particularly cotton can be produced, the mechanical strength of the separator can be further increased.
- the capacitor separator according to an embodiment of the present invention may contain a binder (B) in addition to the fibrillated PVA fiber (A).
- the binder (B) is preferably a polyvinyl alcohol-based binder.
- the binder (B) is bonded to the fibrillated PVA fiber (A). It is possible to obtain a separator having excellent properties and further excellent mechanical strength.
- the binder (B) is a polyvinyl alcohol-based binder, the electrolytic solution resistance and the liquid absorption are excellent.
- a polyvinyl alcohol-type binder is a binder consisting of the said polyvinyl alcohol.
- the binder content is large from the viewpoint of improving the strength of the separator.
- the content of the binder is excessive, the shielding property of the separator cannot be maintained appropriately, and thus there may be a problem that the internal resistance of the capacitor increases.
- the adhesive strength between the main fiber constituting the separator and the binder it is considered that the closer the SP value of the resin constituting the main fiber and the binder resin is, the higher the adhesive strength is.
- the SP value of the resin constituting the binder resin and the fibrillated PVA fiber becomes the same value, so that the adhesive force between the two is improved, and as a result, the binder content is small. Can also impart desired strength to the separator. Therefore, in the present invention, a configuration with a small binder content is possible, and it is easy to ensure a certain shielding property even when the separator is thinned, and the degree of design freedom can be increased.
- Examples of the shape of the binder (B) include a fiber shape, a powder shape, and a solution shape, and a fiber shape is preferable.
- a fiber shape is preferable.
- the binder is in the form of powder or solution, in order to develop the mechanical strength of the separator, it is necessary to dissolve them.
- the composition of the binder (B) Since the resin (for example, polyvinyl alcohol) forms a film and closes the gaps between the fibers of the separator, the electrolyte solution absorbability may decrease and / or the internal resistance of the capacitor may increase.
- the binder (B) is fibrous, the binder (B) is not completely dissolved by means such as reducing the amount of moisture brought in before drying, and only the intersection of the binder fiber and the main fiber remains without leaving the fiber form. It is particularly preferable because it can be point-bonded and the mechanical strength of the separator can be increased without causing a decrease in electrolyte absorption and an increase in internal resistance.
- the fineness thereof is preferably 0.4 to 3 dtex, from the viewpoint of improving the mechanical strength of the separator, suppressing the decrease in electrolyte solution absorbability, and decreasing the internal resistance.
- the fiber length is more preferably 0.7 to 2 dtex, still more preferably 0.8 to 1.5 dtex, and the fiber length is preferably 0.5 to 7 mm, more preferably 1 to 5 mm, still more preferably 2 to 4 mm.
- the dissolution temperature of the polyvinyl alcohol binder in water is preferably 60 to 90 ° C, more preferably 70 to 90 ° C.
- the polyvinyl alcohol binder is preferably a fiber composed of polyvinyl alcohol having an average degree of polymerization of about 500 to 3000 and a saponification degree of 97 to 99 mol%.
- the polyvinyl alcohol binder may be a composite spun fiber or mixed spun fiber (sea island fiber) with another polymer.
- the polyvinyl alcohol constituting the polyvinyl alcohol binder may be a copolymer containing structural units derived from the other monomers.
- the polyvinyl alcohol-based binder preferably contains 30% by weight or more, more preferably 50% by weight or more, and even more preferably 80% by weight or more of a vinyl alcohol structural unit from the viewpoint of electrolyte absorption, mechanical performance, etc. Contains up to 100% by weight.
- the capacitor separator is preferably 1% by weight or more, more preferably 3% by weight or more, further preferably 4% by weight or more, and particularly preferably 5% by weight or more based on the total weight of the separator (B). And preferably 15% by weight or less, more preferably 13% by weight or less, and still more preferably 10% by weight or less of the binder (B).
- the content of the binder (B) in the capacitor separator is equal to or higher than the lower limit, the mechanical strength of the separator can be increased, and problems in manufacturing can be suppressed.
- the content of the binder (B) in the capacitor separator is less than or equal to the above upper limit value, it is excellent in liquid absorbency and further can suppress the formation of a binder film, thereby reducing the internal resistance of the separator capacitor, Furthermore, a decrease in electrolyte solution absorbability can be suppressed.
- the capacitor separator according to an embodiment of the present invention may contain fibrillated fibers (C) other than the fibrillated PVA fibers (A).
- fibrillated fibers include fibrillated cellulose fibers, fibrillated polyolefin fibers (for example, polypropylene fibers, polyethylene fibers, polypropylene / polyethylene composite fibers), fibrillated polyamide fibers, and fibrillated polyester fibers.
- fibrillated cellulose fibers for example, polypropylene fibers, polyethylene fibers, polypropylene / polyethylene composite fibers
- fibrillated polyamide fibers for example, polypropylene fibers, polyethylene fibers, polypropylene / polyethylene composite fibers
- fibrillated polyester fibers for example, polypropylene fibers, polyethylene fibers, polypropylene / polyethylene composite fibers
- fibrillated polyester fibers for example, polypropylene fibers, polyethylene fibers, polypropylene / polyethylene composite fibers
- fibrillated polyester fibers for example,
- the fibrillated cellulose fiber can be obtained by fibrillating the cellulose fiber.
- cellulose fibers include natural cellulose fibers such as rayon fibers (including polynosic rayon fibers and organic solvent-based cellulose fibers), acetate fibers, and natural pulps (wood pulp, cotton linter pulp, hemp, pulp, etc.). It is done. These cellulose fibers may be mercerized. One or two or more of these cellulose fibers are dispersed in water, and fibrillated cellulose fibers are obtained by beating to a predetermined freeness with a paper mill such as a beater, disc refiner, or high-speed beating machine. Can do.
- a paper mill such as a beater, disc refiner, or high-speed beating machine.
- the CSF of the other fibrillated fibers (C) depends on the type of the fibrillated fibers (C), but is, for example, 0 to 700 ml, preferably 0 to 600 ml, more preferably Is 5 to 500 ml, more preferably 10 to 400 ml.
- the CSF of the fibrillated cellulose fibers is preferably 0 to 700 ml, more preferably 0 to 550 ml.
- the capacitor separator preferably contains 10% by weight or more, more preferably 20% by weight or more, and still more preferably 30% by weight or more, preferably 70% by weight, based on the total weight of the separator. Below, more preferably 65% by weight or less, and still more preferably 60% by weight or less of fibrillated cellulose fibers.
- the content of the fibrillated cellulose fiber in the capacitor separator is equal to or higher than the lower limit, the dispersibility of not only the fibrillated cellulose fiber but also the fibrillated PVA fiber (A) is improved. Can be obtained.
- the separator is further excellent in mechanical strength, and the internal resistance of the capacitor can be lowered.
- the capacitor separator according to an embodiment of the present invention may contain a cellulose fiber (D) in addition to the fibrillated PVA fiber (A).
- the capacitor separator includes the cellulose fiber (D)
- the cellulose fiber functions as a skeleton in the separator, so that the mechanical strength can be maintained.
- Cellulose fibers may be mercerized. Examples of the pulp used for mercerized pulp include hardwood pulp, softwood pulp, eucalyptus pulp, esparto pulp, cotton linter pulp, pineapple pulp, manila hemp pulp, and sisal hemp pulp. One or more kinds selected from these pulps can be used, and a mercerization process may be performed.
- the capacitor separator preferably contains 3% by weight or more, more preferably 5% by weight or more, and still more preferably 10% by weight or more, preferably 70% by weight, based on the total weight of the separator. % Or less, more preferably 60% by weight or less, further preferably 50% by weight or less, particularly preferably 40% by weight or less, particularly preferably 30% by weight or less, and very preferably 20% by weight or less of cellulose fiber (D). Including. When the content of the cellulose fiber (D) in the capacitor separator is equal to or higher than the lower limit, an appropriate space can be maintained, and the separator can maintain a certain thickness or more. When the content of the cellulose fiber (D) in the capacitor separator is equal to or lower than the upper limit, the shrinkage rate and the degree of swelling in the electrolytic solution can be suppressed.
- the CSF of the cellulose fiber (D) is usually 450 ml or more, preferably 500 ml or more, more preferably 600 ml or more.
- the shielding property of the separator can be maintained at a certain level or more, and the separator can be maintained at a predetermined thickness.
- the CSF of the cellulose fiber (D) is usually 800 ml or less.
- the air permeability representing the denseness is determined by the beating degree of the constituent components of the separator and the mixing ratio.
- the air permeability of the separator is preferably 0.1 to 10 cc / cm 2 / s, more preferably 0.15 to It is 5 cc / cm 2 / s, more preferably 0.2 to 5 cc / cm 2 / s.
- the air permeability is equal to or higher than the lower limit, the internal resistance of the capacitor can be further reduced. Generation
- the separator When manufacturing a separator, it is common to extract and use the separator wound by roll shape. If the separator does not have a certain tensile strength or more, problems such as the separator being cut during the brewing process may occur. On the other hand, the separator is designed to maintain a constant void (or a constant density) due to its performance, but when the separator is thinned, the basis weight (g / m 2 ) is also a design constraint. It becomes. Therefore, when the separator is made thin, it is necessary for the separator to have, for example, the tensile strength necessary for the brewing process under the constraints of the basis weight design. there were. In the separator of the present invention, by forming the fibrillated PVA fiber in an amount of 30% by weight or more, a thin film can be achieved while maintaining the tensile strength necessary for the separator manufacturing process.
- the thickness of the capacitor separator is preferably 20 to 80 ⁇ m, more preferably 24 to 70 ⁇ m, still more preferably 28 to 60 ⁇ m.
- the thickness of the capacitor separator is equal to or greater than the lower limit, the mechanical strength of the separator can be further increased.
- the thickness of the capacitor separator is equal to or less than the above upper limit value, the path between the electrodes can be shortened, so that the internal resistance of the capacitor can be lowered.
- the basis weight of the capacitor separator is preferably 12 to 30 g / m 2 , more preferably 14 to 26 g / m 2 , and still more preferably 16 to 24 g / m 2 .
- the basis weight of the capacitor separator is equal to or higher than the lower limit, the mechanical strength of the separator can be further increased.
- the basis weight of the capacitor separator is not more than the above upper limit value, the internal resistance of the capacitor can be lowered.
- the specific tensile strength of the capacitor separator is preferably 30 N ⁇ m / g or more, more preferably 30.5 N ⁇ m / g or more, and further preferably 31 N ⁇ m / g or more.
- the specific tensile strength of the capacitor separator is usually 50 N ⁇ m / g or less, particularly 40 N ⁇ m / g or less, for example, 38 N ⁇ m / g or less.
- the specific tensile strength is obtained by dividing the total value of the specific tensile strengths in the longitudinal direction (MD direction) and the transverse direction (TD direction) of the separator measured by JIS P 8113 by 2. It is a numerical value.
- the manufacturing method of the capacitor separator according to one embodiment of the present invention is not particularly limited.
- the said separator is obtained by making it a wet nonwoven fabric using the said fibrillated PVA fiber (A) and a binder (B), another fibrillated fiber (C), and a cellulose fiber (D) as needed.
- a desired wet nonwoven fabric can be efficiently produced by using a general wet paper machine.
- a capacitor separator composed of the fibrillated PVA fiber (A) and, if necessary, a binder (B), another fibrillated fiber (C) and a cellulose fiber (D) can be obtained.
- the capacitor separator is Produced by a method comprising fibrillating a readily fibrillated polyvinyl alcohol fiber comprising polyvinyl alcohol and polyalkylene oxide.
- a fibrillated PVA fiber (A) is obtained by the said process.
- the method also includes Wet paper making fibrillated easily fibrillated polyvinyl alcohol fiber (ie fibrillated PVA fiber (A)) and optionally binder (B), other fibrillated fiber (C) and cellulose fiber (D).
- a step of dispersing in water and making paper may be included.
- Examples of the polyvinyl alcohol contained in the easily fibrillated polyvinyl alcohol fiber include those similar to the polyvinyl alcohol constituting the fibrillated PVA fiber (A).
- the polyalkylene oxide contained in the easily fibrillated polyvinyl alcohol fiber is a polymer having alkylene oxide as a structural unit.
- the polyalkylene oxide may be a polymer having a single alkylene oxide as a structural unit, or may be a copolymer having a plurality of alkylene oxides as a structural unit.
- Examples of the polyalkylene oxide include a polymer having an alkylene oxide having 2 to 6 carbon atoms as a structural unit, specifically, polyethylene oxide, polypropylene oxide, polybutylene oxide, polyisobutylene oxide, and these A copolymer, a mixture, etc. are mentioned.
- the polyalkylene oxide in the present invention may be a copolymer with other monomers or may be modified as long as the effects of the present invention are not impaired.
- the polymerization form of the copolymer is not particularly limited, and may be any of a random shape, a block shape, a graft shape, or a tapered shape.
- the polyalkylene oxide is more preferably at least one selected from the group consisting of polyethylene oxide, polypropylene oxide, and ethylene oxide / propylene oxide copolymer.
- the molar ratio of the ethylene oxide monomer unit to the propylene oxide monomer unit constituting the ethylene oxide / propylene oxide copolymer is preferably 80/20 to 99/1, more preferably 85/15 to 95/5, and even more preferably 88 / from the viewpoint of easy fibrillation. 12-92 / 8.
- the fibrillation property is improved, it is easy to obtain fibrillated fibers having a relatively long fiber length. Therefore, the mechanical strength of the separator including the fibrillated fibers can be increased.
- the weight average molecular weight Mw of the polyalkylene oxide is preferably 50000 or more, more preferably 60000 or more, further preferably 70000 or more, preferably 3000000 or less, more preferably 200000 or less, and further preferably 150,000 or less.
- the weight average molecular weight Mw of the polyalkylene oxide is not less than the above lower limit value, the dispersion state of the polyalkylene oxide in the easily fibrillated polyvinyl alcohol fiber is good, the fibrillation property is also improved, and the mechanical strength of the separator is increased.
- the viscosity of the spinning solution can be easily adjusted in the spinning process, which is desirable from an industrial viewpoint.
- the weight average molecular weight Mw of the polyalkylene oxide is not more than the above upper limit value, the dispersion state of the polyalkylene oxide in the easily fibrillated polyvinyl alcohol fiber is good, the fibrillation property is also improved, and the polyalkylene oxide is further improved in the spinning process. Since the falling off of the oxide is suppressed, a fiber with less fluff (single yarn breakage) can be obtained, and the mechanical strength of the separator can be further increased.
- the weight average molecular weight Mw can be measured by gel permeation chromatography.
- polyalkylene oxide is contained in polyvinyl alcohol fiber and functions as a fibrillation aid.
- the polyvinyl alcohol fiber at least a part of the polyvinyl alcohol and the polyalkylene oxide are not compatible with each other and cause phase separation.
- the structure of the phase separation is not particularly limited, and examples thereof include a sea-island structure, an interconnected structure, and a layered structure. It is considered that at least a part of the polyvinyl alcohol and the polyalkylene oxide causes phase separation in the polyvinyl alcohol fiber, and as a result, the fiber is easily fibrillated.
- the weight ratio of the polyalkylene oxide to the total amount of polyvinyl alcohol and polyalkylene oxide is preferably 3% by weight or more, more preferably 5% by weight or more, and further preferably 7% by weight or more.
- the weight ratio of the polyalkylene oxide is not less than the above lower limit, the fibrillation property of the polyvinyl alcohol fiber is further improved.
- the weight ratio of the polyalkylene oxide is not more than the above upper limit, the ratio of the polyalkylene oxide in the polyvinyl alcohol fiber is kept low, resulting in high adhesion with pulp, alkali resistance and moderate water absorption.
- a separator having high mechanical strength can be obtained, and the spinnability of the easily fibrillated polyvinyl alcohol fiber can be improved.
- a fibrillation aid such as starch or cellulose is used, a large amount of the fibrillation aid must be added to the polyvinyl alcohol fiber in order to cause fibrillation.
- the properties inherent to polyvinyl alcohol may be reduced, for example, the affinity with a polyvinyl alcohol binder may be reduced, and the mechanical strength of the separator may be reduced. May decrease.
- the fiber perfect circle equivalent diameter of the easily fibrillated polyvinyl alcohol fiber is preferably 5 ⁇ m or more, more preferably 7 ⁇ m or more, further preferably 10 ⁇ m or more, preferably 50 ⁇ m or less, more preferably 30 ⁇ m or less, and even more preferably 20 ⁇ m or less. It is.
- the fiber perfect circle diameter of the easily fibrillated polyvinyl alcohol fiber is not less than the above lower limit value, single yarn sticking hardly occurs during spinning, which is industrially advantageous.
- the fiber perfect circle equivalent diameter of the easily fibrillated polyvinyl alcohol fiber is not more than the above upper limit value, a fibrillation efficiency at the time of beating the fiber is good, and a separator having high mechanical strength can be obtained.
- a fiber perfect circle conversion diameter means the diameter of the perfect circle which has the same area as the area of a fiber cross section.
- the easily fibrillated polyvinyl alcohol fiber is A preparation step for preparing a spinning dope comprising polyvinyl alcohol, polyalkylene oxide and water; A spinning process for obtaining fibers by spinning using a spinning dope, It can be produced by a method comprising a drawing step of drawing a fiber, and an acetalization step of acetalizing polyvinyl alcohol contained in the fiber.
- a spinning dope is prepared by dissolving polyvinyl alcohol and polyalkylene oxide in water while heating as necessary. If necessary, boric acid, an alkali component (for example, sodium hydroxide), an antifoaming agent, and the like may be added to the spinning dope.
- concentration of polyvinyl alcohol in the spinning dope is usually 10 to 20% by weight.
- the weight ratio of polyalkylene oxide to the total amount of polyvinyl alcohol and polyalkylene oxide is the same as the weight ratio of polyalkylene oxide to the total amount of polyvinyl alcohol and polyalkylene oxide in the above-described easily fibrillated polyvinyl alcohol fiber.
- the spinning solution is spun from a spinneret into a coagulation bath and dehydrated and solidified.
- the spinneret may be circular, or may have a non-circular shape such as a flat shape, a cross shape, a T shape, a Y shape, an L shape, a triangular shape, a square shape, a star shape, or the like.
- an aqueous solution of an inorganic salt having a dehydrating ability conventionally used for wet spinning of polyvinyl alcohol fibers can be used as the coagulation bath.
- an aqueous solution of sodium sulfate (sodium sulfate decahydrate) is preferably used as the coagulation bath.
- boric acid may be dissolved in the spinning dope and further an alkali may be contained.
- the temperature of the coagulation bath is not particularly limited, but a temperature of about 30 to 50 ° C. is usually preferable because a low temperature is less likely to cause fiber sticking.
- the amount of boric acid added to the spinning stock solution is polyvinyl alcohol and polyalkylene oxide. Based on the total amount, it is preferably 1% by weight or less.
- the amount of boric acid added to the spinning dope is within the above range, crosslinking by boric acid is unlikely to occur during subsequent dry heat stretching, and stretching can be performed smoothly.
- this spinning process is performed by a normal wet coagulation method instead of gel spinning using a coagulation bath made of an aqueous solution of sodium sulfate containing an alkali
- a boric acid washing treatment is performed on the fiber obtained by spinning. It is preferable not to wash the boric acid because the strong hydrophilicity of the carboxyl group contained in the polyvinyl alcohol tends to cause fiber dissolution and sticking. In particular, when the proportion of the carboxyl group in polyvinyl alcohol exceeds 10 mol%, sticking tends to occur.
- the fiber obtained in the spinning step is drawn.
- the fibers are drawn by drawing the fibers from the coagulation bath into the air using a roller.
- This stretching step may be performed by any of a method using a guide and a method using a roller. Further, the stretching may be performed in air, in a high-temperature salt aqueous solution (wet heat stretching), or in combination.
- the stretching ratio is usually 2 to 5 times, preferably about 3 to 4 times.
- a draw ratio means the multiple of the length of the fiber after extending
- the fibers thus obtained are dried to remove moisture, and then dry hot drawing is performed so that the draw ratio is about 2 to 3 times.
- the dry heat stretching is performed so that the total stretching ratio is 6 times or more, preferably 7 times or more, more preferably about 7 to 13 times. Drying is usually performed until the moisture is sufficiently removed at a temperature of about 80 to 140 ° C. without relaxing the tension during spinning drawing, and the subsequent dry heat drawing is performed by heating to about 200 to 240 ° C. in the air. It is preferred to do so.
- the draw ratio of dry heat drawing here refers to the multiple of the fiber length after dry heat drawing relative to the length of the fiber after drawing and before dry heat drawing, and the total draw ratio is The multiple of the length of the fiber after dry heat drawing with respect to the length of the fiber before extending
- stretching is said.
- the fiber obtained in the drawing step is acetalized using an acetal compound.
- acetal compounds include monoaldehydes such as formaldehyde and acetaldehyde; dialdehydes such as glutaraldehyde, hexane dial and nonane dial, and acetals masked by acetalizing the aldehyde groups of these dialdehydes with methanol, ethanol or ethylene glycol And the like.
- formaldehyde is preferable.
- acetalization using formaldehyde is particularly called formalization.
- the acetalization is performed using a composition liquid containing a mineral acid such as sulfuric acid and an acetal compound and, if necessary, a small amount of a mineral salt.
- a mineral acid such as sulfuric acid and an acetal compound
- the mineral acid include inorganic acids such as sulfuric acid, phosphoric acid, nitric acid and chromic acid, and organic acids such as carboxylic acid and sulfonic acid.
- the concentration of the mineral acid in the composition liquid is usually 0.3 to 3 mol / l, and the concentration of the acetal compound is usually 0.6 to 7 mol / l.
- the temperature of the composition liquid in the acetalization step is usually 50 to 90 ° C., preferably 60 to 80 ° C.
- the degree of acetalization of the fiber in the acetalization step is preferably 3 mol% or more, more preferably 6 mol% or more, still more preferably 8 mol% or more, even more preferably 10 mol% or more, preferably 40 mol%. Below, more preferably 30 mol% or less, still more preferably 20 mol% or less, and even more preferably 15 mol% or less.
- the degree of acetalization of polyvinyl alcohol is not less than the above lower limit, easily fibrillated polyvinyl alcohol fibers excellent in water resistance can be obtained.
- the degree of acetalization of polyvinyl alcohol is not more than the above upper limit value, the fibrillation property of the resulting polyvinyl alcohol fiber is further improved.
- the easily fibrillated polyvinyl alcohol fiber can be produced. Since the easily fibrillated polyvinyl alcohol fiber uses a water-soluble polyalkylene oxide without using a cellulose polymer or the like, it can be spun using an aqueous solution instead of an organic solvent. In the case of spinning using an organic solvent, the total production cost including solvent recovery and the like is high. However, in one embodiment of the present invention, as described above, aqueous spinning using an aqueous solution can be performed. This is possible and can be spun without recovering the organic solvent, so that the manufacturing cost can be kept low.
- the method for fibrillation of the easily fibrillated polyvinyl alcohol fiber is not particularly limited.
- the easily fibrillated fiber can be fibrillated by chemical swelling force and mechanical stress, either alone or in combination.
- the chemical swelling power represents the ability to swell the constituent components of fibers such as polyvinyl alcohol and polyalkylene oxide.
- the swelling agent which swells these structural components is not specifically limited, For example, water is mentioned.
- the mechanical stress can be applied by a mixer, a beater, a refiner, and / or a screw that applies a shearing force to the polyvinyl alcohol fiber.
- Examples of the fibrillation method of the easily fibrillated polyvinyl alcohol fiber include a method in which the fiber is cut and short fibers are used.
- the fiber is cut into 1 to 30 mm, immersed and dispersed in water, and subjected to mechanical stress using a mixer or the like to perform fibrillation.
- a fibrillated PVA fiber (A) can be obtained.
- the average diameter of the fibrillated PVA fiber (A) is, for example, 0.05 to 8 ⁇ m.
- the average diameter of the fibrillated PVA fiber (A) means the diameter of a perfect circle having the same area as the area of the fibril cross section.
- the average diameter of fibrils can be measured using, for example, a scanning or transmission electron microscope.
- the fibrillated PVA fiber (A) obtained as described above and, if necessary, the binder (B), other fibrillated fiber (C) and cellulose fiber (D) are dispersed in water in a wet paper machine.
- Papermaking nets are used in wet paper machines. Examples of papermaking nets include circular nets, short nets, and long nets. These papermaking nets can be used alone to form a single layer or to make paper. It is also possible to combine multiple layers by combining nets. In order to obtain a homogeneous paper with excellent formation and no electrical unevenness, it is preferable to make a multi-layered paper. Among them, a short-to-circular paper machine is preferred to make a double-layered paper. preferable.
- a capacitor separator is obtained by making paper with a wet paper machine and then drying with a Yankee dryer. Of course, hot pressing can be further performed as necessary. Furthermore, it is also possible to improve electrolyte solution absorptivity by performing hydrophilic treatment, such as surfactant treatment. Moreover, in order to improve the permeability of the electrolytic solution to the separator, the separator can be subjected to gravure processing and / or embossing.
- a capacitor particularly an electric double layer capacitor, including the separator
- a capacitor can be manufactured by disposing the separator between a positive electrode and a negative electrode to form an element, and impregnating the element with an electrolytic solution.
- the kind of the positive electrode and the negative electrode in the capacitor and the kind of the electrolytic solution are not particularly limited, and those conventionally used in capacitors, particularly electric double layer capacitors, can be used.
- an aqueous electrolyte for example, nitric acid aqueous solution
- an organic electrolyte non-aqueous electrolyte
- the separator according to another embodiment of the present invention is suitable as a separator for an electric double layer capacitor that includes a carbonaceous positive electrode and a negative electrode and uses an organic electrolyte (non-aqueous electrolyte) as an electrolyte.
- organic electrolyte include salts of tetraalkylammonium cations and anions such as BF 4 ⁇ , PF 6 ⁇ , SO 3 CF 3 ⁇ , AsF 6 ⁇ , N (SO 2 CF 3 ) 2 ⁇ , and ClO 4 ⁇ .
- an electrolytic solution in which is dissolved in an organic solvent such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, sulfolane, and methyl sulfolane.
- organic solvent such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, sulfolane, and methyl sulfolane.
- the use and usage of the separator in a capacitor can also be provided.
- the capacitor separator can be used not only for capacitors but also for battery separators, filters, wipers, packaging materials, abrasives, insulating paper, heat-resistant paper, and the like.
- the aspect ratio of the fibrillated PVA fibers 20 PVA fibers in a fibrillated state are arbitrarily collected, the width and length of each fiber taken out by an optical microscope are measured, and the aspect ratio is calculated based on the numerical values. It measured by calculating
- fibers other than PVA fibers are included, after removing fibers other than fibrillated PVA fibers by a dissolution method according to the fiber identification method, arbitrarily collect 20 fibrillated PVA fibers Then, the width and length of each fiber taken out by an optical microscope were measured, the aspect ratio was calculated based on the numerical value, and the average value of the 20 fibers was obtained.
- the fiber perfect circle equivalent diameter was calculated
- the fineness was measured in accordance with JIS L 1013 “Testing method for chemical fiber filament yarn”, positive fineness 8.3.1 b), and the fiber true-circle equivalent diameter was calculated from the fineness according to the following calculation formula.
- Diameter ( ⁇ m) 10 ⁇ Fineness (dtex)
- the thickness (mm) of the sample was measured according to JIS P 8118 “Testing method for thickness and density of paper and paperboard”.
- Basis weight The basis weight (g / m 2 ) of the sample was measured according to JIS P 8124 “Measuring basis weight of paper”.
- the tensile strength (kN / m) in the longitudinal and lateral directions of the sample (separator) was measured according to JIS P 8113 “Testing method for tensile strength of paper and paperboard”.
- the tensile strength is a value obtained by dividing the total value of the tensile strength in the longitudinal direction and the transverse direction of the separator by 2.
- the specific tensile strength (N ⁇ m / g) of the sample was calculated according to JIS P 8113 “Testing method of tensile strength of paper and paperboard”.
- the specific tensile strength is preferably 30 N ⁇ m / g or more.
- the spinning solution contains 0.003% by weight of a surfactant (manufactured by Miyoshi Oil Chemical Co., Ltd., VL-22) and 0.002% by weight of an antifoaming agent (manufactured by Nippon Kasei Chemical Co., Ltd., Jolshin LB-D). Added.
- a spinneret having a hole number of 1000 and a hole diameter of 80 ⁇ m ⁇ (circular) into a coagulation bath composed of a saturated sodium sulfate aqueous solution at 45 ° C.
- the wet heat stretching was performed 4 times stepwise from the two rollers to the drying roller, followed by drying at 130 ° C. Subsequently, the film was stretched twice. Thereafter, using a composition liquid containing 2 mol / l sulfuric acid (mineral acid) and 1 mol / l formaldehyde, an acetalization treatment is performed at 70 ° C., and the degree of acetalization (degree of formalization) of polyvinyl alcohol is 10 mol. %, Easily fibrillated polyvinyl alcohol fiber was obtained. The fiber-like diameter of the resulting easily fibrillated polyvinyl alcohol fiber was 14 ⁇ m (size before beating).
- the easily fibrillated polyvinyl alcohol fiber obtained was cut into 2 mm, 5 g of this fiber was dispersed in 1000 ml of water at 20 ° C., and a mixer (manufactured by Matsushita Electric Industrial Co., Ltd., MX-152S, rotation speed: 9700 rpm) was used. Beat for 5 minutes. The obtained beating solution was filtered to obtain a cotton-like fibrillated PVA fiber.
- This fibrillated PVA fiber had a CSF of 10 ml and an aspect ratio of 500 or more.
- An optical micrograph of the fibrillated PVA fiber is shown in FIG.
- Example 1 40% by weight of the fibrillated PVA fiber obtained in Production Example 1, 40% by weight of the fibrillated cellulose fiber obtained in Production Example 2, 15% by weight of mercerized pulp (merceled LBKP (unbeaten)), and polyvinyl alcohol type A slurry was prepared by dispersing 5% by weight of binder fiber (manufactured by Kuraray Co., Ltd., vinylon binder: VPB105-1 ⁇ 3, fineness: 1.1 dtex, fiber length: 3 mm, dissolution temperature in water: 74 ° C.) in water.
- binder fiber manufactured by Kuraray Co., Ltd., vinylon binder: VPB105-1 ⁇ 3, fineness: 1.1 dtex, fiber length: 3 mm, dissolution temperature in water: 74 ° C.
- Example 2 to 3 and Comparative Examples 1 to 5 Separators were obtained in the same manner as in Example 1, except that the amounts of fibrillated PVA fiber, fibrillated cellulose fiber, mercerized pulp, and polyvinyl alcohol-based binder fiber were changed according to Table 1. Various evaluations were performed on this separator. The results are shown in Table 2.
- Example 1 except that polyvinyl alcohol fibers having an aspect ratio of 121 and an unbeaten (CSF: 780 ml) were used in place of fibrillated PVA fibers having an aspect ratio of 500 or more and CSF of 10 ml according to Table 1. In the same manner, a separator was obtained. Various evaluations were performed on this separator. The results are shown in Table 2.
Abstract
Description
〔1〕ポリビニルアルコール系樹脂のみからなるフィブリル化繊維を、該セパレータの全重量に基づいて30重量%以上含むキャパシタ用セパレータ。
〔2〕前記ポリビニルアルコール系樹脂のみからなるフィブリル化繊維は綿状である、前記〔1〕に記載のキャパシタ用セパレータ。
〔3〕前記ポリビニルアルコール系樹脂のみからなるフィブリル化繊維のアスペクト比は500以上である、前記〔1〕または〔2〕に記載のキャパシタ用セパレータ。
〔4〕バインダーとしてポリビニルアルコール系樹脂を15重量%以下含む、前記〔1〕~〔3〕のいずれかに記載のキャパシタ用セパレータ。
〔5〕前記ポリビニルアルコール系樹脂のみからなるフィブリル化繊維のCSFが5~500mlである、前記〔1〕~〔4〕のいずれかに記載のキャパシタ用セパレータ。
〔6〕厚さが20~80μmであり、比引張強さが30N・m/g以上である、前記〔1〕~〔5〕のいずれかに記載のキャパシタ用セパレータ。
〔7〕ポリビニルアルコールおよびポリアルキレンオキシドを含む易フィブリル化ポリビニルアルコール繊維をフィブリル化する工程を含む、前記〔1〕~〔6〕のいずれかに記載のキャパシタ用セパレータの製造方法。
〔8〕前記易フィブリル化ポリビニルアルコール繊維における、ポリビニルアルコールおよびポリアルキレンオキシドの総量に対するポリアルキレンオキシドの重量比率が3~40重量%である、前記〔7〕に記載のキャパシタ用セパレータの製造方法。
〔9〕前記〔1〕~〔6〕のいずれかに記載のキャパシタ用セパレータを含むキャパシタ。
ポリビニルアルコールおよびポリアルキレンオキシドを含む易フィブリル化ポリビニルアルコール繊維をフィブリル化する工程を含む、方法によって製造される。上記工程により、フィブリル化PVA繊維(A)が得られる。
また、該方法は、
フィブリル化された易フィブリル化ポリビニルアルコール繊維(即ち、フィブリル化PVA繊維(A))、ならびに必要に応じてバインダー(B)、他のフィブリル化繊維(C)およびセルロース繊維(D)を、湿式抄紙機において、水に分散させ、抄造する工程
を含んでもよい。
この場合、上記フィブリル化された易フィブリル化ポリビニルアルコール繊維に含まれるポリアルキレンオキシドが、叩解工程および/または抄造工程において水に溶出するため、叩解工程および/または抄造工程を経ることで、ポリビニルアルコールのみからなるフィブリル化PVA繊維(A)を容易に調製することが可能である。
ポリビニルアルコール、ポリアルキレンオキシドおよび水を含む紡糸原液を調製する調製工程、
紡糸原液を用いて紡糸を行うことによって繊維を得る紡糸工程、
繊維を延伸する延伸工程、および
繊維に含まれるポリビニルアルコールをアセタール化するアセタール化工程
を含む方法によって製造することができる。
試料繊維の繊度は、JIS L 1013「化学繊維フィラメント糸試験方法」正量繊度 8.3.1 b)に準じて繊度(dtex)を測定した。
フィブリル化PVA繊維のアスペクト比は、フィブリル化状態のPVA繊維を任意に20本採取し、光学顕微鏡により取り出した各繊維の巾と長さを測定し、その数値に基づいてアスペクト比を算出し、その20本の平均値を求めることによって測定した。PVA繊維以外の繊維が含まれている場合には、繊維の識別方法に準じた溶解法によりフィブリル化状態のPVA繊維以外の繊維を除去した後、フィブリル化状態のPVA繊維を任意に20本採取し、光学顕微鏡により取り出した各繊維の巾と長さを測定し、その数値に基づいてアスペクト比を算出し、その20本の平均値を求めることによって測定した。
易フィブリル化ポリビニルアルコール繊維の繊度(dtex)からの換算によって、繊維真円換算直径を求めた。JIS L 1013「化学繊維フィラメント糸試験方法」正量繊度 8.3.1 b)に準じて繊度を測定し、その繊度から次の計算式に従って、繊維真円換算直径を算出した。
直径(μm)=10√繊度(dtex)
固体13C-NMRを用いて、ホルムアルデヒド(アセタール化合物)とポリビニルアルコールとのアセタール結合に由来するピーク面積とポリビニルアルコールのメチン炭素ピーク面積との比から、試料のアセタール化度(モル%)を求めた。
400ccの水(20℃)に試料繊維を2.6g投入し、昇温速度1℃/min、攪拌速度280rpmの条件で攪拌しながら昇温し、繊維が完全に溶解したときの温度を測定し、水中溶解温度(℃)とした。
JIS P 8121「パルプの濾水度試験方法」に準じて、試料のカナダ標準濾水度(ml)を測定した。
JIS P 8118「紙及び板紙の厚さと密度の試験方法」に準じて、試料の厚さ(mm)を測定した。
JIS P 8124「紙のメートル坪量測定方法」に準じて、試料の坪量(g/m2)を測定した。
JIS P 8113「紙及び板紙の引張強さ試験方法」に準じて、試料(セパレータ)の縦方向および横方向の引張強さ(kN/m)を測定した。本発明においては、セパレータの縦方向および横方向の引張強さの合計値を2で割った数値を引張強さとした。また、測定した引張強さおよび坪量に基づいて、JIS P 8113「紙及び板紙の引張強さ試験方法」に準じて、試料の比引張強さ(N・m/g)を算出した。比引張強さは30N・m/g以上であることが好ましい。
JIS L 1096 6.27「一般織物試験方法 通気性」に準じ、フラジール形試験機を用いて、試料の通気度(cc/cm2/sec)を測定した。
以下の実施例および比較例で作製した電気二重層キャパシタを、充電電流20mAにて2.7Vまで充電後、2.7Vの定電圧条件にて2時間充電を行い、放電電流20mAにて0Vまで放電を行った。内部抵抗値(Ω)は、前記したサイクルの放電直後の電圧低下より求めた。内部抵抗値は1.4Ω以下であることが好ましい。
ポリビニルアルコール(粘度平均重合度:1700、ケン化度:99.9モル%)を水に溶解させ、15重量%のポリビニルアルコール水溶液を調製した。次に、ポリエチレンオキシド(重量平均分子量Mw:80000)を、ポリビニルアルコールおよびポリエチレンオキシドの総量に対して10重量%添加し、紡糸原液を調製した。紡糸原液には、紡糸性向上の目的で界面活性剤(ミヨシ油化製、VL-22)0.003重量%および消泡剤(新日化成製、ジョルシンLB-D)0.002重量%を添加した。この紡糸原液を用いて、90℃において、穴数1000、穴径80μmφ(円形)の紡糸口金より45℃の飽和硫酸ナトリウム水溶液からなる凝固浴中に吐出させ、第1ローラーで引き取った後、第2ローラーを経て乾燥ローラーまで段階的に4倍の湿熱延伸を行い、その後130℃で乾燥を行った。引き続き2倍の延伸を行った。その後、2モル/lの硫酸(鉱酸)および1モル/lのホルムアルデヒドを含む組成液を用いて、70℃においてアセタール化処理を行い、ポリビニルアルコールのアセタール化度(ホルマール化度)を10モル%とし、易フィブリル化ポリビニルアルコール繊維を得た。得られた易フィブリル化ポリビニルアルコール繊維の繊維真円換算直径は14μm(叩解前のサイズ)であった。
フィブリル化可能なセルロース繊維(レンチング社製、リヨセル、繊度:1.7dtex、繊維長:3mm)を製造例1と同様の処理を実施して、CSFが10mlのフィブリル化セルロース繊維を得た。
製造例1で得られたフィブリル化PVA繊維40重量%、製造例2で得られたフィブリル化セルロース繊維40重量%、マーセル化パルプ(マーセル化LBKP(未叩解))15重量%、およびポリビニルアルコール系バインダー繊維(クラレ社製、ビニロンバインダー:VPB105-1×3、繊度:1.1dtex、繊維長:3mm、水中溶解温度:74℃)5重量%を、水中に分散させて、スラリーを調製した。このスラリーを用いて、短網-円網抄紙機にて2層抄き合わせ抄紙を行い、ヤンキー型乾燥機にて乾燥し、坪量18.8g/m2、厚さ0.030mmのセパレータを得た。このセパレータについて、各種評価を行った。結果を表2に示す。
フィブリル化PVA繊維、フィブリル化セルロース繊維、マーセル化パルプ、およびポリビニルアルコール系バインダー繊維の使用量を、表1に従って変更した以外は、実施例1と同様にして、セパレータをそれぞれ得た。このセパレータについて、各種評価を行った。結果を表2に示す。
表1に従って、アスペクト比が500以上、CSFが10mlであるフィブリル化PVA繊維に代えて、アスペクト比が121であり、未叩解(CSF:780ml)のポリビニルアルコール繊維を用いた以外は、実施例1と同様にして、セパレータを得た。このセパレータについて、各種評価を行った。結果を表2に示す。
Claims (9)
- ポリビニルアルコール系樹脂のみからなるフィブリル化繊維を、該セパレータの全重量に基づいて30重量%以上含むキャパシタ用セパレータ。
- 前記ポリビニルアルコール系樹脂のみからなるフィブリル化繊維は綿状である、請求項1に記載のキャパシタ用セパレータ。
- 前記ポリビニルアルコール系樹脂のみからなるフィブリル化繊維のアスペクト比は500以上である、請求項1または2に記載のキャパシタ用セパレータ。
- バインダーとしてポリビニルアルコール系樹脂を15重量%以下含む、請求項1~3のいずれかに記載のキャパシタ用セパレータ。
- 前記ポリビニルアルコール系樹脂のみからなるフィブリル化繊維のCSFが5~500mlである、請求項1~4のいずれかに記載のキャパシタ用セパレータ。
- 厚さが20~80μmであり、比引張強さが30N・m/g以上である、請求項1~5のいずれかに記載のキャパシタ用セパレータ。
- ポリビニルアルコールおよびポリアルキレンオキシドを含む易フィブリル化ポリビニルアルコール繊維をフィブリル化する工程を含む、請求項1~6のいずれかに記載のキャパシタ用セパレータの製造方法。
- 前記易フィブリル化ポリビニルアルコール繊維における、ポリビニルアルコールおよびポリアルキレンオキシドの総量に対するポリアルキレンオキシドの重量比率が3~40重量%である、請求項7に記載のキャパシタ用セパレータの製造方法。
- 請求項1~6のいずれかに記載のキャパシタ用セパレータを含むキャパシタ。
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EP17820290.9A EP3480836A4 (en) | 2016-06-30 | 2017-06-29 | SEPARATOR FOR CAPACITOR |
CN201780040052.3A CN109416981A (zh) | 2016-06-30 | 2017-06-29 | 电容器用隔板 |
US16/313,504 US20190318884A1 (en) | 2016-06-30 | 2017-06-29 | Separator for capacitor |
JP2018525272A JPWO2018003936A1 (ja) | 2016-06-30 | 2017-06-29 | キャパシタ用セパレータ |
KR1020187035814A KR20190022519A (ko) | 2016-06-30 | 2017-06-29 | 커패시터용 세퍼레이터 |
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FR3069056B1 (fr) * | 2017-07-13 | 2020-09-25 | Saint Gobain Isover | Procede de quantification de l'humidite dans un matelas de fibres |
JP6989414B2 (ja) * | 2018-02-27 | 2022-01-05 | ニッポン高度紙工業株式会社 | 電気化学素子用セパレータ及び電気化学素子 |
CN111009425B (zh) * | 2019-12-11 | 2021-06-22 | 东佳电子(郴州)有限公司 | 一种低噪抗击穿超级电容器 |
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