JP4648841B2 - Separator for electronic parts - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excellently heat-resisting and highly reliable separator for an electronic component. <P>SOLUTION: The separator for an electronic component is made of a wet non-woven fabric which, in thermal expansion measurements to 300 &deg;C at a rate of temperature rise 10 &deg;C/min under a tensile load 4 KPa, measures 0.7 mm&times;min or less in the integration value of an area enclosed by both a straight line and a TMA curve ranging from 50 &deg;C to the temperature at which a maximum length is attained of the concerned specimen and further measures less than 2.0 % in the maximum degree of elongation in the temperature range from 50 &deg;C to 300 &deg;C. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to a highly reliable separator for electronic parts having excellent heat resistance.

  Conventionally, paper separators mainly composed of regenerated cellulose or solvent-spun cellulose (for example, see Patent Documents 1 and 2) have been used as separators for electric double layer capacitors. In an electric double layer capacitor equipped with an electrolyte solution consisting of an organic solvent and an electrolyte, even if a small amount of water is mixed, the voltage does not reach the specified voltage, the voltage fluctuates, the internal resistance increases, and so on. The electric double layer capacitor is manufactured after the electrodes and the separator are dried together at a high temperature for a long time to remove moisture contained in these members. Electrolytic paper and separators mainly composed of solvent-spun cellulose have a problem that the cellulose component is carbonized or decomposed when treated at a high temperature of 200 ° C. or higher, and when using an electrode that repeats volume expansion and contraction due to charge and discharge, There was a problem that the separator was torn. Recently, an aramid thin leaf material excellent in heat resistance (see, for example, Patent Document 3) has been proposed, but there are problems of low strength and difficulty in handling and poor durability.

Conventionally, as a separator of an electrolytic capacitor, a paper separator mainly composed of regenerated cellulose or solvent-spun cellulose (for example, see Patent Document 4) has been used. However, these separators have problems such as an increase in internal resistance and an increase in leakage current after the solder reflow in the solder reflow using the high melting point solder accompanying the recent lead removal of the solder.
JP-A-11-168033 JP 2000-3834 A JP 2005-307360 A JP-A-5-267103

  An object of the present invention is to provide a highly reliable separator for electronic parts that is excellent in heat resistance.

  As a result of intensive studies to solve the above problems, the present inventors have found that a TMA area and an elongation rate are specific in a curve (hereinafter referred to as a TMA curve) obtained by measuring thermal expansion under specific conditions. The present inventors have found that a separator for electronic parts made of a wet nonwoven fabric in the range is excellent in heat resistance and can realize a high-performance electronic part.

That is, the present invention relates to a TMA from 50 ° C. up to the maximum sample length when the thermal expansion measurement is performed up to 300 ° C. at a tensile load of 4 KPa and a temperature increase rate of 10 ° C./min. For an electronic component in which the integral value of the portion surrounded by the curve and the straight line is 0.01 to 0.48 mm × min and the maximum elongation from 50 ° C. to 300 ° C. is 0.8 to 1.8% . It is a separator.

In the present invention, the wet nonwoven fabric has three components, fibrillated heat-resistant fiber, non-fibrillated heat-resistant fiber, and fibrillated cellulose as essential components, and the total content of the essential three components is 45 to 100% by mass, non-fibrillated. in the content of the non-heat-resistant fiber 55-0 by mass%, the total content of fibrillated heat-resistant fiber and a non-fibrillated heat-resistant fiber is Ru der least 40 wt%.

  In the present invention, the fibrillated heat-resistant fiber is preferably a fibrillated para-type wholly aromatic polyamide fiber.

  In the present invention, the non-fibrillated heat-resistant fiber is preferably a non-fibrillated para-type wholly aromatic polyamide fiber.

  In the present invention, the electronic component is preferably an electric double layer capacitor.

  In the present invention, the electronic component is preferably an electrolytic capacitor.

  According to the present invention, a highly reliable separator for electronic parts having excellent heat resistance can be obtained.

  Hereinafter, the electronic component separator of the present invention will be described in detail.

  The electronic component in the present invention has a power storage function configured by sandwiching a dielectric or electric double layer between two opposing electrodes. The former includes aluminum electrolytic capacitors and tantalum electrolytic capacitors, and has functions such as noise absorption and resonance in addition to the power storage function. The latter includes an electric double layer capacitor. The electrode of the electric double layer capacitor may be a combination of a pair of electric double layer electrodes, one of which is an electric double layer electrode and the other is a redox electrode. The electrolyte includes an aqueous solution in which an ion dissociable salt is dissolved, propylene carbonate (abbreviation PC), ethylene carbonate (abbreviation EC), dimethyl carbonate (abbreviation DMC), diethyl carbonate (abbreviation DEC), acetonitrile (abbreviation AN), γ-butyrolactone (abbreviation BL), dimethylformamide (abbreviation DMF), tetrahydrofuran (abbreviation THF), dimethoxyethane (abbreviation DME), dimethoxymethane (abbreviation DMM), sulfolane (abbreviation SL), dimethyl sulfoxide (abbreviation DMSO), ethylene glycol Examples thereof include, but are not limited to, those obtained by dissolving an ion dissociable salt in an organic solvent such as propylene glycol, and ionic liquids (solid molten salts). In the case of an electrochemical element that can use both an aqueous solution system and an organic solvent system, an organic solvent system is preferred because the aqueous solution system has a low withstand voltage. Instead of the electrolytic solution, a conductive polymer film such as polypyrrole, polythiophene, polyaniline, polyacetylene, and derivatives thereof may be used.

  TMA used in the present invention is a method of measuring the deformation of a substance as a function of temperature by applying a non-vibrating load such as compression, tension, bending, and twisting while changing the temperature of a sample. Furthermore, thermal expansion measurement uses a probe whose tip can support the chuck, and fixes the upper and lower ends of the sample with two small chucks so that the sample does not deform in the tensile temperature range in the measurement temperature range. This is a method for measuring displacement due to thermal expansion when a load is applied, and a TMA curve is obtained by taking temperature or time on the horizontal axis.

The separator for electronic parts of the present invention is surrounded by a TMA curve and a straight line from 50 ° C. up to the maximum sample length when the thermal expansion is measured up to 300 ° C. at a tensile load of 4 KPa and a heating rate of 10 ° C./min. The integrated value of the part is 0.01 to 0.48 mm × min , and the maximum elongation from 50 ° C. to 300 ° C. is 0.8 to 1.8% , which means that the TMA curve is linear. This means that the electronic component separator does not expand or contract rapidly or greatly in the tensile direction as the temperature rises, or does not cut. Therefore, the electronic component separator of the present invention is not easily deformed or deteriorated even when exposed to a high temperature of 200 ° C. or higher, particularly 230 ° C. or higher. In the present invention, the temperature reaching the maximum sample length is preferably 280 to 300 ° C, and is preferably closer to 300 ° C. The maximum elongation from 50 ° C. to 300 ° C. means that the sample length at 50 ° C. is L ₅₀ and the maximum sample length between 300 ° C. is L _max (L _max −L ₅₀ ). / L ₅₀ indicates a value calculated by ₅₀ × 100. When the TMA area is larger than 0.48 mm × min or the maximum elongation is more than 1.8% , it means that the electronic component separator rapidly expands, contracts or cuts as the temperature rises. . The rapid expansion / contraction or cutting of the electronic component separator is caused by softening, melting, deterioration, decomposition, or the like of the fibers constituting the electronic component separator. Therefore, when the separator having a maximum elongation exceeding 1.8% is treated at a high temperature of 200 ° C. or higher, particularly 230 ° C. or higher, the entanglement and bonding strength between fibers become weak, and the electrolyte solution is impregnated. When the electrode that expands and contracts due to charging / discharging is used when an impact or load such as vibration, collision, or dropping is applied to the electronic component equipped with the separator, The separator is broken or cracked, and a fatal defect is likely to occur in the electronic component. In addition, when an electronic component equipped with the separator is soldered, the internal resistance and voltage become unstable or show abnormal values because the shape of the separator is deformed or a part of the gap of the separator is blocked. There is a case. The maximum growth rate is Ru der 0.8% or more.

  The heat resistant fiber in the present invention refers to a fiber having a softening point, a melting point, and a thermal decomposition temperature of 250 ° C. or more and 700 ° C. or less. Specifically, wholly aromatic polyamide, wholly aromatic polyester, wholly aromatic polyester amide, wholly aromatic polyether, wholly aromatic polycarbonate, wholly aromatic polyazomethine, polyphenylene sulfide (abbreviation PPS), poly (para-phenylene) Benzobisthiazole) (abbreviation PBZT), polybenzimidazole (abbreviation PBI), polyetheretherketone (abbreviation PEEK), polyamideimide (abbreviation PAI), polyimide, polytetrafluoroethylene (abbreviation PTFE), poly (para-phenylene- 2,6-benzobisoxazole) (abbreviation PBO), and these may be used alone or in combination of two or more. PBZT may be either a transformer type or a cis type. Here, although the softening point and the melting point are not clear in the category of “softening point, melting point, and thermal decomposition temperature are all 250 ° C. or higher and 700 ° C. or lower”, the thermal decomposition temperature is 250 ° C. or higher and 700 ° C. or lower. Some are included. Examples include wholly aromatic polyamides and PBO. Among these fibers, para-type wholly aromatic polyamide fibers that are easy to be fibrillated uniformly due to liquid crystallinity are preferable.

  The para-type wholly aromatic polyamide in the present invention is a polymer obtained by polycondensation of a para-oriented aromatic diamine and a para-oriented aromatic dicarboxylic acid halide. A polymer obtained by polycondensation of an aromatic diamine, meta-oriented aromatic dihalide, aliphatic diamine, aliphatic dicarboxylic acid, etc., from a repeating unit in which the amide bond is bonded at the para position of the aromatic ring or an oriented position equivalent thereto It is the polymer which becomes. Further, some hydrogen atoms of the aromatic rings of the para-oriented aromatic diamine and the para-oriented aromatic dicarboxylic acid halide may be substituted with a substituent that does not form an amide bond, and the aromatic ring may be polycyclic. Examples of the substituent that does not form an amide bond include an alkyl group, an alkoxy group, a halogen, a sulfonyl group, a nitro group, a phenyl group, and the like. Since an alkyl group and an alkoxy group tend to inhibit polycondensation when the number of carbon atoms is long, the number of carbon atoms is preferably 1 to 4. For example, as the para-oriented aromatic diamine in which a part of hydrogen atoms in the aromatic ring is substituted with an alkyl group, N, N′-dimethylparaphenylenediamine, N, N′-diethylparaphenylenediamine, 2-methyl-4 -Ethylparaphenylenediamine, 2-methyl-4-ethyl-5-propylparaphenylenediamine and the like are exemplified, but not limited thereto. For example, the para-oriented aromatic dicarboxylic acid halide in which a part of hydrogen atoms of the aromatic ring is substituted with an alkoxy group includes dimethoxyterephthalic acid chloride, diethoxyterephthalic acid chloride, 2-methoxy-4-ethoxyterephthalic acid chloride, and the like. Although it is mentioned, it is not limited to these. For example, the para-oriented aromatic diamine having a polycyclic aromatic ring includes 4,4′-oxydiphenyldiamine, 4,4′-sulfonyldiphenyldiamine, 4,4′-diphenyldiamine, and 3,3′-oxydiphenyldiamine. 3,3′-sulfonyldiphenyldiamine, 3,3′-diphenyldiamine, and the like, but are not limited thereto. Further, as described above, some of the hydrogen atoms of these aromatic rings may be substituted with a substituent that does not form an amide bond. For example, the para-oriented aromatic dicarboxylic acid halide having a polycyclic aromatic ring includes 4,4′-oxydibenzoyl chloride, 4,4′-sulfonyldibenzoyl chloride, 4,4′-dibenzoyl chloride, 3,3 Examples include, but are not limited to, '-oxydibenzoyl chloride, 3,3'-sulfonyldibenzoyl chloride, 3,3'-dibenzoyl chloride. Furthermore, as described above, some of the hydrogen atoms of these aromatic rings may be substituted with a substituent that does not form an amide bond.

  As the para-type wholly aromatic polyamide in the present invention, poly (para-phenylene terephthalamide) and copoly (para-phenylene-3,4'-oxydiphenylene terephthalamide) which are particularly excellent in heat resistance are preferable among the above-mentioned polymers. .

  The fibril in the present invention is not a film, but a fiber having a portion finely divided mainly in a direction parallel to the fiber axis, and at least a part of the fiber has a fiber diameter of 1 μm or less. The manufacturing method and shape are different from fibrids. The aspect ratio of length to width is distributed in the range of about 20 to about 100,000, and the Canadian standard freeness is preferably in the range of 0 to 500 ml or less, and more preferably in the range of 0 to 200 ml. Furthermore, what has a weight average fiber length in the range of 0.1-2 mm is preferable.

  Fibrilization in the present invention includes refiner, beater, mill, grinding device, rotary blade homogenizer that applies shearing force by high-speed rotary blade, cylindrical inner blade that rotates at high speed, and fixed outer blade. Double-cylindrical high-speed homogenizer that generates shearing force, ultrasonic crusher that is refined by ultrasonic impact, a pressure difference of at least 3000 psi is applied to the fiber suspension, and a small-diameter orifice is passed through to increase the speed. Is carried out using a high-pressure homogenizer or the like that applies a shearing force or a cutting force to the fiber by rapidly decelerating the fibers, and it is particularly preferable to treat with a high-pressure homogenizer because fine fibrils can be obtained.

  Fibrids are non-granular, non-rigid fibrous or film-like fine particles. In the case of fibrous, the diameter and length are in the range of μm. In the case of film, the thickness, width, and length Any one of the sizes is in the range of μm. Fibrids are produced by shear precipitation of a polymer solution into a poor solvent (coagulation bath) as specified in US Pat. No. 2,999,788 and US Pat. No. 30,180,091.

  The non-fibrillated heat-resistant fiber in the present invention refers to the above-mentioned heat-resistant fiber that has not been fibrillated. The fineness of the non-fibrillated heat resistant fiber is preferably 0.01 to 1.5 dtex, more preferably 0.1 to 0.9 dtex. If the fineness is less than 0.01 dtex, the fiber tends to be brittle. When it is larger than 1.5 dtex, the electronic component separator tends to be rough, which may cause an internal short circuit. In the present invention, among non-fibrillated heat-resistant fibers, all para-types such as poly (para-phenylene terephthalamide) and copoly (para-phenylene-3,4'-oxydiphenylene terephthalamide), which are particularly excellent in heat resistance, are used. Aromatic polyamide fibers are preferred.

  Non-fibrillated non-heat-resistant fibers in the present invention include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene isophthalate, and derivatives thereof, polyolefins, acrylonitrile copolymers (acrylic), aliphatic polyamides, and semi-aromatic polyamides. , Polyethersulfone (abbreviated as PES), polyvinylidene fluoride, polyvinyl alcohol, polyurethane, polyvinyl chloride, and the like. These may be one type or a mixture of two or more types. . Here, the semi-aromatic refers to a substance having, for example, a fatty chain in a part of the main chain, but is not limited thereto. Among these, a fiber made of an acrylonitrile copolymer is preferable because it has an effect of reducing the TMA area and the elongation rate. A core-sheath composite fiber in which the core part is made of a resin having a high melting point such as polyethylene terephthalate and the sheath part is made of a resin containing a low melting point component such as polyethylene isophthalate is preferable because the strength of the separator for electronic parts is increased.

  The fineness of the non-fibrillated non-heat resistant fiber in the present invention is preferably 0.01 to 2.0 dtex. If the fineness is less than 0.01 dtex, the fibers are too thin to form the basic skeleton of the wet nonwoven fabric. When the fineness is larger than 2.0 dtex, the fibrillated heat-resistant fiber and the fibrillated cellulose tend to fall off, and as a result, pinholes are easily formed and the texture tends to be uneven. The fiber length of the non-fibrillated non-heat resistant fiber is preferably 1 mm to 15 mm, and more preferably 2 mm to 10 mm. When the fiber length is shorter than 1 mm, it is easy to fall off from the electronic component separator. When the fiber length is longer than 15 mm, the fiber tends to get tangled and become lumpy, and uneven thickness tends to occur.

  The fibrillated cellulose in the present invention refers to bacterial cellulose or mechanically fibrillated cellulose. The former refers to bacterial cellulose produced by microorganisms. This bacterial cellulose contains cellulose and a heteropolysaccharide having cellulose as a main chain, and also contains glucans such as β-1,3, β-1,2, and the like. Constituent components other than cellulose in the case of heteropolysaccharides are hexoses such as mannose, fructose, galactose, xylose, arabinose, rhamnose, glucuronic acid, pentoses, organic acids and the like. These polysaccharides may be composed of a single substance, or may be composed of two or more kinds of polysaccharides bonded together by hydrogen bonds or the like, and any of them can be used.

  The latter refers to fibrillated materials similar to the above-described fibrillated heat-resistant fibers, which are made from various pulps such as linter, lint and the like. Fibrilized cellulose and bacterial cellulose obtained from these natural celluloses are preferable because they have a large effect of reducing the TMA area.

  The wet nonwoven fabric of the present invention has three components, fibrillated heat-resistant fiber, non-fibrillated heat-resistant fiber, and fibrillated cellulose as essential components, and the total content of the essential three components is 45 to 100% by mass, non-fibrillated and non-heat-resistant. It is preferable that the content of the conductive fiber is 55 to 0% by mass and the total content of the fibrillated heat resistant fiber and the non-fibrillated heat resistant fiber is 40% by mass or more. If this condition is not satisfied, the required heat resistance is difficult to obtain, and a highly reliable electronic component may not be obtained.

  The wet nonwoven fabric in the present invention is wet using a long paper machine, a short paper machine, a circular paper machine, an inclined paper machine, a combination machine in which two or more of the same or different types of paper machines are combined. Manufactured by papermaking. The water used for wet papermaking is preferably ion-exchanged water, and dispersion aids and other additive chemicals, release agents, etc. are preferably nonionic, so long as they do not affect the characteristics of electronic components. An appropriate amount of ionic substances may be used.

Although there is no restriction | limiting in particular in the basic weight of the separator for electronic components in this invention, 5-50 g / m < ² > is preferable and 8-35 g / m < ² > is used more preferable.

  The thickness of the electronic component separator in the present invention is not particularly limited, but it is preferably thinner from the viewpoint that the electronic component can be miniaturized, the electrode area that can be accommodated can be increased, and the capacity can be increased. Specifically, 10 to 300 μm is preferably used as the thickness having strength that does not break when assembling electronic components, no pinholes, and high uniformity, and 20 to 100 μm, more preferably 20 to 60 μm is more preferably used. . If it is less than 10 μm, the short-circuit failure rate during the production of electronic components increases, which is not preferable. On the other hand, when the thickness is greater than 300 μm, the electrode area that can be accommodated in the electronic component is reduced, and the capacity of the electronic component is low.

  The electronic component separator of the present invention is subjected to thermal processing such as calendering, thermal calendering, and heat treatment as necessary. In the case of heat treatment, the treatment is preferably performed at a temperature of 150 ° C to 300 ° C. When the temperature is lower than 150 ° C., the heat treatment tends to be insufficient, and when the temperature is higher than 300 ° C., the heat shrinks easily.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, the content of this invention is not limited to an Example.

<Preparation of fibrillated heat resistant fiber 1>
Para-type wholly aromatic polyamide fiber (manufactured by Teijin Techno Products, Twaron 1080) was dispersed in ion-exchanged water so as to have an initial concentration of 5%, and was repeatedly beaten 15 times using a double disc refiner to obtain a weight average fiber length. A fibrillated para-type wholly aromatic polyamide fiber of 1.35 mm and Canadian standard freeness 90 ml was produced. Hereinafter, this is referred to as fibrillated heat resistant fiber 1 or FB1.

<Preparation of fibrillated heat resistant fiber 2>
The fibrillated heat-resistant fiber 1 was further repeatedly beaten with a high-pressure homogenizer 25 times under the condition of 50 MPa to produce a fibrillated para-type wholly aromatic polyamide fiber having a weight average fiber length of 0.58 mm and a Canadian standard freeness of 0 ml. Hereinafter, this is referred to as fibrillated heat resistant fiber 2 or FB2.

<Para-type wholly aromatic polyamide fiber 1>
Poly (para-phenylene terephthalamide) resin was subjected to liquid crystal spinning and washed to prepare a tow having a fineness of 0.1 dtex. This was cut into a length of 3 mm to produce a para-type wholly aromatic polyamide fiber. Hereinafter, this is referred to as para-type wholly aromatic polyamide fiber 1 or PA1.

<Polyester fiber 1>
A polyethylene terephthalate resin was melt-spun and stretched to produce a tow having a fineness of 0.05 dtex. This was cut into a length of 3 mm to obtain a polyethylene terephthalate fiber. Hereinafter, this is referred to as polyester fiber 1 or PET1.

<Acrylic fiber 1>
An acrylonitrile copolymer comprising three components of acrylonitrile, methyl acrylate and vinyl acetate was wet-spun, washed and stretched to produce a tow having a fineness of 0.01 dtex. This was cut into a length of 2 mm to obtain an acrylic fiber. Hereinafter, this is referred to as acrylic fiber 1 or A1.

<Preparation of fibrillated cellulose 1>
Disperse linters in ion-exchanged water to a concentration of 5% and repeat the treatment 20 times at a pressure of 50 MPa using a high-pressure homogenizer to produce fibrillated cellulose with a weight average fiber length of 0.33 mm and Canadian standard freeness of 0 ml. did. Hereinafter, this is referred to as fibrillated cellulose 1 or FBC1.

<Preparation of fibrillated cellulose 2>
Hemp fibers are dispersed in ion-exchanged water, beaten with a beater, and repeatedly treated 20 times at a pressure of 50 MPa using a high-pressure homogenizer to produce fibrillated cellulose having a weight average fiber length of 0.45 mm and Canadian standard freeness of 0 ml. did. Hereinafter, this is referred to as fibrillated cellulose 2 or FBC2.

<Production of meta-type wholly aromatic polyamide fibrid>
While stirring a methylene chloride solution in which a predetermined amount of poly (meta-phenylene isophthalamide), triethylamine, and triethylamine hydrochloride was stirred with a Warin blender, a methylene chloride solution in which isophthalic acid chloride was dissolved was added to cause a polycondensation reaction. Poly (meta-phenylene isophthalamide) was synthesized. A coagulation bath mixed at a ratio of 30% N, N'-dimethylacetamide, 68% water and 2% calcium chloride is stirred at a high speed with a Warin blender, and a poly (meta-phenylene isophthalamide) solution is brought into contact therewith to form an aramid. Fibrids were precipitated. The obtained aramid fibrid was washed with water. Hereinafter, this is referred to as meta-type wholly aromatic polyamide fibrid 1 or FD1. The Canadian freeness of FD1 was 30 ml.

  A papermaking slurry was prepared according to the raw materials and blending amounts shown in Table 1. Here, “PET2” in Table 1 is a polyethylene terephthalate fiber having a fineness of 0.1 dtex and a fiber length of 3 mm (Teijin Fibers, Tepyrus TM04PN), and “PET3” is a core-sheath composite having a fineness of 1.1 dtex and a fiber length of 5 mm. It means fiber (manufactured by Teijin Fibers, TJ04CN, core: polyethylene terephthalate having a melting point of 255 ° C., sheath: copolymer of polyethylene terephthalate and polyethylene isophthalate, melting point 110 ° C.). “A2” is an acrylic fiber having a fineness of 0.1 dtex and a fiber length of 3 mm (acrylonitrile copolymer comprising three components of Mitsubishi Rayon, Bonnell MVP, acrylonitrile, methyl acrylate, and methacrylic acid derivative), “ “A3” means acrylic fiber (manufactured by Mitsubishi Rayon, Bonnell MVP, acrylonitrile, methyl acrylate, methacrylic acid derivative acrylonitrile copolymer having a fineness of 0.4 dtex and a fiber length of 3 mm). . "PA2" is a para-type wholly aromatic polyamide fiber having a fineness of 0.75 dtex and a fiber length of 3 mm (manufactured by Teijin Techno Products, Technora, copoly (para-phenylene-3,4'-oxydiphenylene terephthalamide)), "PA3 Is a para-type wholly aromatic polyamide fiber having a fineness of 1.2 dtex and a fiber length of 5 mm (manufactured by Teijin Techno Products, Twaron 1080, poly (para-phenylene terephthalamide)), and “PA4” has a fineness of 0.08 dtex and a fiber length. It means 3 mm aromatic polyamide fiber (manufactured by Kuraray, Genesta, melting point 255 ° C., softening point 230 ° C.). “P1” is solvent-spun cellulose (Tencel, manufactured by Lenzing Co., Ltd.) beaten to 20 ml Canadian Standard Freeness, “P2” is Polynosic Rayon with 500 ml Canadian Standard Freeness, and “P3” is 640 ml of Manila hemp means.

Examples 1-18
Slurries 1-18 were wet-machined using a combination of a circular paper machine and a circular paper machine, and calendared at a linear pressure of 10-500 N / cm to produce separators 1-18 for electronic parts.

(Comparative Examples 1 and 2)
Slurries 19 and 20 were subjected to wet paper making using a long paper machine and calendered at a linear pressure of 10 to 500 N / cm to produce separators 19 and 20 for electronic parts.

(Comparative Examples 3 to 7)
Slurries 21 to 25 were subjected to wet paper making using a circular paper machine and a combination paper machine, and calendar treatment was performed at a linear pressure of 10 to 500 N / cm to produce separators 21 to 25 for electronic parts.

<Production of electric double layer capacitor>
A sheet-like electrode having a thickness of 0.2 mm was prepared by kneading 85% nonporous carbon as an electrode active material, 10% carbon black as a conductive material, and 5% polytetrafluoroethylene as a binder. This was adhered to both surfaces of an aluminum foil having a thickness of 50 μm using a conductive adhesive, and rolled to produce an electrode. This electrode was used as a positive electrode and a negative electrode. A separator for an electronic component was laminated between the negative electrode and the positive electrode, and wound into a spiral shape using a winding machine to produce a spiral element. Both the positive electrode side and the negative electrode side were provided with electronic component separators. This spiral element was housed in an aluminum case. The positive electrode lead and the negative electrode lead were welded to the positive electrode terminal and the negative electrode terminal attached to the case, and then the case was sealed leaving the electrolyte injection port. The case containing this element was heated to 240 ° C. for 20 hours and dried. However, the electronic components 19 and 20 were heated to 200 ° C. for 40 hours. After allowing this to cool to room temperature, an electrolytic solution was injected into the case, and the liquid inlet was sealed to produce an electric double layer capacitor. As the electrolytic solution, a solution obtained by dissolving (C ₂ H ₅ ) ₃ (CH ₃ ) NBF ₄ in propylene carbonate so as to have a concentration of 1.5 mol / l was used.

<Production of electrolytic capacitor>
An aluminum foil having a thickness of 50 μm and an etching hole diameter of 1 to 5 μm was used as an electrode. After spot welding the anode connector on one side of the electrode, the electrode was immersed in a boric acid solution maintained at a temperature of 90 ° C. The aluminum foil surface was oxidized for a minute to form an aluminum oxide dielectric layer. This was used as an anode. Similarly, a cathode connector was spot welded to one side of an etched aluminum foil electrode and used as a cathode. An electronic component separator is placed on the anode dielectric layer, wound together with the cathode, and then inserted into a cell for an electrolytic capacitor. Electrolyte (tetraethylammonium phthalate 24.1% by mass, γ-butyrolactone 70% by mass) %, Ethylene glycol 5.9% by mass), and the cell was sealed to produce an aluminum electrolytic capacitor.

  The electronic component separator, the electric double layer capacitor, and the electrolytic capacitor were measured by the following test methods, and the results are shown in Tables 2 and 3 below.

<Thickness>
The thicknesses of the electronic component separators 1 to 25 were measured according to JIS C2111, and the results are shown in Table 2.

<Density>
The density of the electronic component separators 1 to 25 was measured according to JIS C2111, and the results are shown in Table 2.

<TMA area>
The separator for electronic parts was cut into a strip of 5 mm width × 13 mm length so as to be long in the MD (machine direction) direction, and both ends of the sample were fixed with a chuck for a TMA apparatus (Perkin Elmer, TMA7). The fixed sample is hooked on the hook of a quartz tensile probe, and the temperature is increased from room temperature to 300 ° C. in a nitrogen gas atmosphere under the conditions of a tensile load of 4 KPa and a temperature increase rate of 10 ° C./min. It was measured. The TMA area was determined from the integral value of the portion surrounded by the TMA curve and the straight line from 50 ° C. to the maximum sample length, and is shown in Table 2.

<Elongation>
The sample length at 50 ° C. detected in the thermal expansion measurement in the <TMA area> section is L ₅₀ , the maximum sample length is L _max, and the elongation percentage of the electronic component separator is calculated from the following equation (1). The results are shown in Table 2.
Elongation rate (%) = (L _max −L ₅₀ ) / L ₅₀ × 100 (1)

<Maximum sample length temperature>
Table 2 shows the temperature at which the sample length reached the maximum in the thermal expansion measurement in the <TMA area> section. A higher temperature is preferable.

<DC resistance>
The electric double layer capacitor was calculated from the voltage drop immediately after the start of discharge when a constant current of 20 A was discharged after charging to 3.3 V, and is shown in Table 3.

<Durability>
After charging the electric double layer capacitor to 3.3V, charging / discharging to discharge to 2.0V was repeated 500 times. Table 3 shows the ratio (%) at which the separator was normally operated 500 times without breaking through even when the electrode expanded in volume. The expansion pressure of the electrode was 0.3 MPa. It means that it is excellent in durability, so that a numerical value is large.

<Leakage current after reflow>
The leakage current after 1 minute of solder reflow treatment at 230 ° C. or higher including 30 seconds at a peak temperature of 260 ° C. was measured on the electrolytic capacitor.

As shown in Table 2, the separators for electronic components of Examples 1 to 18 were temperatures that reached the maximum sample length from 50 ° C. when the thermal expansion was measured up to 300 ° C. at a tensile load of 4 KPa and a temperature increase rate of 10 ° C./min. The integral value of the portion surrounded by the TMA curve and the straight line was 0.01 to 0.48 mm × min , and the maximum elongation was 0.8 to 1.8% . Therefore, the separator hardly deteriorates even when treated at a high temperature of 200 ° C. or higher, and the electric double layer capacitor provided with the separator has low DC resistance and excellent durability. In addition, the electrolytic capacitor provided with the separator was excellent in that the leakage current after the high-temperature solder reflow treatment was small.

On the other hand, since the separators for electronic parts of Comparative Examples 1 and 2 are 100% cellulose, the maximum sample length is reached from 50 ° C. when the thermal expansion measurement is performed up to 300 ° C. at a tensile load of 4 KPa and a heating rate of 10 ° C./min. The integral value of the portion surrounded by the TMA curve and the straight line up to the measured temperature was larger than 0.48 mm × min . The electric double layer capacitor provided with the separator was dried at 200 ° C., which is lower than that of the example, in the manufacturing process. Therefore, although the DC resistance was low, the durability was extremely poor. The electrolytic capacitor provided with the separator has a large leakage current after the high-temperature solder reflow treatment.

  Since the separator for electronic parts of Comparative Example 3 was weak, the sample was cut in the thermal expansion measurement, and the TMA area could not be measured.

The separators for electronic parts of Comparative Examples 4 to 6 are surrounded by a TMA curve and a straight line from 50 ° C. when the thermal expansion measurement is performed at a tensile load of 4 KPa and a temperature increase rate of 10 ° C./min to the temperature reaching the maximum sample length. The integral value of the part was larger than 0.48 mm × min , and the maximum elongation was more than 1.8%. Therefore , the electric double layer capacitor equipped with the separator has a high or slightly high DC resistance and a high durability. It was inferior. Further, the electrolytic capacitor equipped with the separator has a large leakage current after the high-temperature solder reflow treatment.

The separator for electronic parts of Comparative Example 7 is a portion surrounded by a TMA curve and a straight line from 50 ° C. to the maximum sample length when the thermal expansion measurement is performed at a tensile load of 4 KPa and a temperature increase rate of 10 ° C./min. Therefore , the electric double layer capacitor equipped with the separator had high DC resistance and poor durability. Further, the electrolytic capacitor equipped with the separator has a large leakage current after the high-temperature solder reflow treatment.

  Examples of applications of the present invention include applications that require heat resistance and high reliability, for example, separators for electronic parts such as electric double layer capacitors and electrolytic capacitors.

Claims (5)

The integral value of the portion surrounded by the TMA curve and the straight line from 50 ° C. to the temperature reaching the maximum sample length when the thermal expansion measurement is performed up to 300 ° C. at a tensile load of 4 KPa and a temperature increase rate of 10 ° C./min is 0.01 in ～0.48Mm × min, and, Ri maximum elongation of up to 300 ° C. from 50 ° C. is Do the wet-laid nonwoven fabric is from 0.8 to 1.8%, the wet nonwoven fabric, softening point, melting point, thermal decomposition temperature These are fibrillated heat-resistant fibers having a temperature of 250 ° C. or more and 700 ° C. or less, non-fibrillated heat-resistant fibers or fibrillated cellulose having a softening point, melting point, or thermal decomposition temperature of 250 ° C. or more and 700 ° C. or less. These three components are essential components, the total content of the essential three components is 45 to 100% by mass, the content of non-fibrillated non-heat-resistant fibers is 55 to 0% by mass, fibrillated heat-resistant fibers and non-fibrillated heat-resistant fibers The total content of sexual fibers Electronic component separator is 0 mass% or more. Fibrillated heat-resistant fiber is, the electronic component separator according to claim 1 which is fibrillated para-type wholly aromatic polyamide fibers. Non fibrillated heat-resistant fiber is, the electronic component separator according to claim 1 which is non-fibrillated para-type wholly aromatic polyamide fibers. Electronic components, electronic component separator according to any one of claims 1-3, characterized in that the electric double layer capacitor. The electronic component separator according to any one of claims 1 to 3 , wherein the electronic component is an electrolytic capacitor.