JP2009295483A - Thinned material, its manufacturing method, and electric/electronic part using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To develop a partitioning material of low resistance and high heat resistance as well for resisting large current due to electric/electronic parts having larger capacity and larger output. <P>SOLUTION: The thinned material includes meta-aramid short fiber and heat resisting porous particles and furthermore at least one out of aramid fibrid and fibrillated aramid. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a thin leaf material useful as a separator (separator) for separating conductive members in an electric / electronic component and allowing an ion species such as an electrolyte or ions to pass through, a method for manufacturing the same, and an electric / electronic component using the same About. Particularly, a thin leaf material useful as a separator between electrodes of a battery, a capacitor, a fuel cell, a solar cell or the like using lithium ions, sodium ions, ammonium ions, hydrogen ions, iodide ions, etc. as a current carrier, and a method for producing the same In addition, the present invention relates to electrical / electronic parts using the same.

As symbolized by recent advances in portable communication devices and high-speed information processing devices, there are remarkable improvements in the size and weight and performance of electronic devices. In particular, there are great expectations for high-performance batteries, capacitors, fuel cells, and solar cells that are compact, lightweight, have high capacity and can withstand long-term storage, are widely applied, and parts development is progressing rapidly. In order to meet this demand, there is an increasing need for technical and quality development of a member, for example, a separator as a partition material between electrodes. Among the various characteristics required for the separator, the following three characteristic items are recognized as particularly important.
1) Good conductivity with electrolyte retained.
2) High shielding property between electrodes.
3) Have mechanical strength.

  Conventionally, a porous sheet (Patent Document 1) formed using a polyolefin-based polymer such as polyethylene or polypropylene, a non-woven fabric (Patent Document 2) formed using the polymer fiber, and a sheet formed using nylon fiber Nonwoven fabrics (Patent Document 3) are widely used as separators. Such a separator is used in a battery by being wound in one or more layers or in a roll shape.

  These microporous membranes and non-woven fabrics have good physical properties as separators. However, in recent years, for high capacity and high output required for batteries for electric vehicles, capacitors, fuel cells, solar cells, etc. It is not always enough.

For separators in electrical and electronic parts such as batteries, capacitors, fuel cells, solar cells, etc. that require high capacity and high output,
1) Good conductivity in a state where the electrolyte is held (low resistance).
2) High shielding property between electrodes.
3) Have mechanical strength.
4) Chemically and electrochemically stable (heat resistance).
It is necessary to satisfy these four characteristics simultaneously. In particular, electrical conductivity and heat resistance are extremely important in terms of efficiently storing regenerative energy of brakes in electric and electronic parts such as batteries and capacitors as driving power sources for electric vehicles that use large currents. it is conceivable that.

As means for improving the heat resistance, conventionally, separators containing inorganic particles such as silica particles and glass fibers (Patent Documents 4 to 8) have been disclosed as separators containing a heat-resistant binder. Because of the inherently weak glass fiber, the glass fiber tends to break when thinned by hot pressing, and the mechanical properties are degraded, making it difficult to maintain the shape of the separator and handle it in the manufacturing process. Components such as acrylic resin, cationic fixing reinforcing agent, and polymer flocculant are added to fix inorganic particles on the separator, but the withstand voltage decreases due to these agents remaining in the separator. There are problems such as a decrease in electrochemical stability.

JP-A 63-273651 JP 2001-11761 A Japanese Patent Laid-Open No. 58-147756 JP 2004-207261 A JP 2004-349586 A JP 2006-059613 A JP 2007-81035 A JP 2007-317045 A

  An object of the present invention is to develop a low-resistance and high-heat-resistant separator (separator) material that can withstand a large current due to an increase in capacity and output of electric / electronic parts.

  As a result of diligent studies to achieve the above object, the present inventors have completed the present invention.

  Thus, the present invention provides a thin leaf material characterized in that it comprises meta type aramid short fibers, heat-resistant porous particles, and optionally at least one of aramid fibrids and fibrillated aramids. It is.

The present invention also provides a sheet of meta-aramid short fibers and, optionally, at least one of aramid fibrids and fibrillated aramids by a wet papermaking method, and heat resistant by a fluid spray method at any point in the process. Provided is a method for producing the above-mentioned thin leaf material, characterized in that porous particles are added, and the obtained sheet is hot-pressed at a temperature higher than the glass transition temperature of the meta-type aramid between a pair of metal rolls. It is.
The present invention further provides an electric / electronic component, for example, a battery, a capacitor, a fuel cell, a solar cell, etc., using the thin leaf material as a separator between conductive members.

  The thin leaf material of the present invention is considered to have sufficiently low internal resistance, sufficient ion species permeability, and high shielding properties between electrodes, so it is used as a separator between conductive members in electrical and electronic parts. can do. In addition, since electric and electronic parts such as batteries and capacitors using the thin leaf material of the present invention essentially contain meta-aramid and heat-resistant porous particles having high heat resistance, they can be used in a large current environment such as electric vehicles. But it can be used.

  Hereinafter, the present invention will be described in more detail.

BEST MODE FOR CARRYING OUT THE INVENTION

Meta-type aramid :
In the present invention, meta-aramid means a linear polymer compound in which 60% or more of amide bonds are directly bonded to the meta position of an aromatic ring (for example, benzene ring). Examples of such meta-type aramids include polymetaphenylene isophthalamide and copolymers thereof. These meta-type aramids are industrially produced by, for example, conventionally known interfacial polymerization methods, solution polymerization methods, etc. using isophthalic acid chloride and metaphenylenediamine, and can be obtained as commercial products. It is not limited to this. Among these meta-type aramids, polymetaphenylene isophthalamide is preferably used from the viewpoint of having good molding processability, thermal adhesiveness, flame retardancy, heat resistance and the like.

Meta-type aramid short fiber :
Meta-type aramid short fibers are obtained by cutting fibers made from meta-type aramids. Examples of such fibers include “Teijin Conex (registered trademark)” by Teijin Limited, “ Although what can be obtained with brand names, such as "NOMEX (trademark)", is mentioned, It is not limited to these.

The meta-type aramid short fibers can preferably have a fineness within a range of 0.05 dtex or more and less than 25 dtex, particularly 0.1 to 1 dtex. Here, the fineness is defined as the fiber weight (g) per 1000 m length. A fiber having a fineness of less than 0.05 dtex is not preferred because it tends to cause aggregation in the production by a wet papermaking method (described later), and a fiber having a fineness of 25 dtex or more has a too large fiber diameter. When the density is 1.4 g / cm ³ , when the diameter is 45 microns or more, there may be inconveniences such as a decrease in aspect ratio, a reduction in mechanical reinforcement effect, and poor uniformity of the thin leaf material. Here, the poor uniformity of the thin leaf material means that the distribution of the gap size is widened and the above-described ionic species mobility is not uniform.

  The length of the meta-type aramid short fibers is generally 1 mm or more and less than 50 mm, particularly preferably in the range of 2 to 10 mm. If the length of the short fiber is smaller than 1 mm, the mechanical properties of the thin leaf material are likely to deteriorate. On the other hand, those having a length of 50 mm or more are “entangled” or “bound” in the production of the thin leaf material by the wet papermaking method described later. Are likely to occur and cause defects.

Heat resistant porous particles :
In the present invention, the heat-resistant porous particle means a particulate material having a heat resistance equivalent to or higher than that of the meta-type aramid and having a hollow portion. The hollow portion is preferably a through-hole from the viewpoint of improving the permeability of the ionic substance when immersed in the electrolytic solution, that is, the conductivity while holding the electrolyte.

As the heat-resistant porous particles, for example, mesoporous silica can be used, but is not limited thereto. The heat-resistant porous particles are generally from 0.1 to 25 μm, particularly from 1 to 25 μm, particularly from 1 to 25 μm from the viewpoint of hardly causing an increase in internal resistance without causing deterioration of impregnation and permeation of the electrolyte while being bound by entanglement with fibers Although it is preferable to have an average particle diameter in the range of 15 μm, it is not limited to this. Also, from the viewpoint of short circuit prevention measures when the separator is thinned for large capacity and low resistance, the hole diameter of the hollow portion is generally 1 to 100 nm, particularly 2 to 10 nm, and the volume is generally about 0.3 to about 2 cm. ³ / g, particularly in the range of about 0.5 to about 1.5 cm ³ / g, is preferred, but not limited thereto. Examples of such heat-resistant porous particles include those that can be obtained under trade names such as “TMPS (registered trademark)” of Taiyo Kagaku Co., Ltd., but are not limited thereto.

Aramid Five :
Aramid fibrids are film-form aramid particles having papermaking properties and are also called aramid pulp (see Japanese Patent Publication No. 35-11851, Japanese Patent Publication No. 37-5752 and the like).

It is widely known that aramid fibrids can be used as a papermaking raw material after being disaggregated and beaten in the same way as ordinary wood pulp, and so-called beating can be performed for the purpose of maintaining quality suitable for papermaking. . This beating process can be carried out by a paper refiner, a beater, or other papermaking raw material processing equipment having a mechanical cutting action. In this operation, the change in the form of fibrid can be monitored by the freeness test method defined in Japanese Industrial Standard (JIS) P8121. In the present invention, the freeness of the aramid fibrid after the beating treatment is generally in the range of 10 to 300 cm ³ , particularly 10 to 50 cm ³ (Canadian Freeness). For fibrids with a freeness greater than this range, the strength of the aramid thin leaf material formed therefrom may decrease, and if a freeness smaller than 10 cm ³ is to be obtained, the utilization efficiency of the mechanical power to be input In many cases, the processing amount per unit time is reduced, and the so-called binder function is liable to be lowered because the fibrids are too fine. Therefore, even if it is going to obtain the freeness smaller than 10 cm < ³ >, a remarkable advantage is not recognized.

  For the use of the present invention, it is preferable that the weight average fiber length measured with an optical fiber length measuring device after beating the aramid fibrid is 1 mm or less, particularly 0.7 mm or less. Here, as the optical fiber length measuring device, for example, a measuring device such as a Fiber Quality Analyzer (manufactured by Op Test Equipment) or a kayany type measuring device (manufactured by Kayani) can be used. In such an instrument, the fiber length and morphology of aramid fibrids passing through a certain optical path are individually observed and the measured fiber length is statistically processed, but the weight averaged fibers of the aramid fibrids used When the length exceeds 1 mm, the electrolyte solution absorbability decreases, partial electrolyte non-impregnation occurs, and the internal resistance of electric / electronic parts increases.

Fibrilized aramid :
Fibrilized aramid is fibrillated by applying shear force to aramid fibers, aramid fibrids, etc., and the freeness is generally in the range of 10 to 800 cm ³ , especially 10 to 200 cm ³ (Canadian Freeness). It is preferable to be within. A fibrillated aramid with a freeness greater than this range may not ensure sufficient shielding between the electrodes, and conversely, attempts to obtain a freeness less than 10 cm ³ were fibrillated. Since so-called aramid refinement proceeds too much, the so-called binder function tends to be lowered. Therefore, even if it is going to obtain a freeness smaller than 10 cm ³ in this way, no significant advantage is recognized.

The fibrillated aramid preferably has a specific surface area of generally 5 g / m ² or more, particularly 10 g / m ² or more. When the specific surface area is smaller than 5 g / m ² , the binder function tends to be lowered. Further, the fibrillated aramid preferably has a weight average fiber length of generally 0.01 mm or more and less than 7 mm, particularly 0.1 to 3 mm. A fibrillated aramid having a weight average fiber length larger than this range has a poor dispersibility during papermaking and may cause local defects such as fiber agglomerates of aramid thin paper. When trying to obtain a small weight average fiber length, the so-called binder function is likely to be lowered because the fibrillated aramid is excessively refined. Specific examples of fibrillated aramids include those available under the trade names such as DuPont's "Kevlar Pulp (registered trademark)" and Teijin Twaron "Twaron Pulp (registered trademark)". However, it is not limited to these.

Thin leaf material :
The thin leaf material of the present invention is a sheet-like material mainly composed of at least one of the above-described meta-type aramid short fibers and heat-resistant porous particles, or these two components, and further aramid fibrid and fibrillated aramid. The content, basis weight and density (basis weight / thickness) of meta-type aramid short fibers, heat-resistant porous particles, aramid fibrids and fibrillated aramids are not strictly limited, and are intended for thin leaf materials It can be changed over a wide range depending on the purpose of use. However, the thin leaf material of the present invention is mainly composed of a meta-aramid short fiber having high heat resistance as a main component, and heat-resistant porous particles, aramid fibrids, and fibrillated aramid are often minor components, and in particular, a pair of materials described later. When high-temperature hot pressing is performed between the metal rolls at a temperature higher than the glass transition temperature of the meta-type aramid, the lower the content of the meta-type aramid short fiber, the lower the density of the leaf material can be produced and the lower the internal resistance value. Due to the tendency, the meta-aramid short fiber content is usually 30% (weight ratio) or more, especially 35-50% (weight ratio), and the heat-resistant porous particles, aramid fibrids and fibrillated aramids in total Usually, it is preferably 70% (weight ratio) or less, particularly 50 to 65% (weight ratio).

  In addition, the thin leaf material generally has a thickness in the range of 5 to 1000 μm, particularly 7 to 100 μm. If the thickness is smaller than 5 μm, the mechanical properties are deteriorated, and it is easy to cause problems in maintaining the form as a separator and handling in the manufacturing process. Conversely, if it exceeds 1000 μm, the internal resistance is likely to increase. It becomes difficult to manufacture small, high-performance electric / electronic components.

Furthermore, the thin leaf material can generally have a basis weight in the range of 5 to 1000 g / m ² , in particular 5 to 30 g / m ² . If the basis weight is 5 g / m ² less than for the mechanical strength is insufficient, it tends to cause a rupture in the various handling in component manufacturing processes such as electrolyte impregnation and winding, contrary to the 1000 g / m ² greater than the basis weight Thin leaf materials tend to cause an increase in thickness and a decrease in electrolyte impregnation and permeation.

The density of thin sheet material is a value calculated from the basis weight / thickness, usually 0.1~1.2g / ^{m 3,} it can be particularly take a value in the range of 0.2-0.5 g / ^{m 3} .

In the thin leaf material of the present invention, the value represented by the internal resistance value (μm) / basis weight (g / m ² ) is preferably 9 or less, particularly 8.5 or less. Here, the internal resistance value is a value represented by the following expression (1).

(Internal resistance value) = (Electric conductivity of electrolyte) / {(Electricity when electrolyte is injected into separator
Air conductivity) × (Separator thickness)} Formula (1)

In the formula, (electrical conductivity when the electrolyte is injected into the separator) is the electric conductivity calculated from the AC impedance measured between the two electrodes with the electrolyte injected into the separator. Here, the electrolytic solution means a liquid in which an electrolyte is dissolved in a solvent.

  In the measurement of the internal resistance value, there are no particular limitations on the solvent, electrolyte, electrolyte concentration, etc. used in the electrolytic solution. Examples of the solvent include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate ethyl methyl carbonate. , Butylene carbonate, glutaronitrile, adiponitrile, acetonitonyl, methoxyacetonitrile, 3-methoxypropionitrile, γ-butyrolactone, γ-valerolactone, sulfolane, 3-methylsulfolane, nitroethane, nitromethane, trimethyl phosphate, N-methyloxazolidinone , N, N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, N, N′-cymethylimidazolidinone, amidine, water and mixtures thereof.

Examples of the electrolyte include ionic substances, particularly combinations of the following cations and anions.
1) Cations: quaternary ammonium ions, quaternary phosphonium ions, lithium ions, sodium ions, ammonium ions, hydrogen ions and mixtures thereof.
2) Anion: perchlorate ion, borofluoride ion, hexafluorophosphate ion, sulfate ion, hydroxide ion and mixtures thereof.

  In the present invention, (electrical conductivity when an electrolyte is injected into the separator) is an electric conductivity calculated from an alternating current impedance measured between two electrodes in a state where the electrolytic solution is injected into the separator. Means. Although there is no restriction | limiting in particular about the measurement frequency of alternating current impedance, 1 kHz-100 kHz are preferable.

In addition, the thin leaf material in which the value represented by the internal resistance value (μm) / basis weight (g / m ² ) exceeds 9 causes a problem that the output of electric / electronic parts is hindered.

Production of thin leaf materials :
The thin leaf material of the present invention having the characteristics as described above is generally composed of the above-mentioned meta-type aramid short fibers and heat-resistant porous particles or ta-type aramid short fibers, heat-resistant porous particles, aramid fibrids and fibrillated aramids. It can manufacture by the method of mixing at least 1 type of them, and making it into a sheet. Specifically, for example, after dry blending at least one of the meta-type aramid short fibers, heat-resistant porous particles or ta-type aramid short fibers, heat-resistant porous particles and aramid fibrids and fibrillated aramids, Method of forming sheet using air flow; meta type aramid short fiber and heat-resistant porous particle or ta-type aramid short fiber, heat-resistant porous particle and aramid fibrid and fibrillated aramid at least one kind as liquid medium After being dispersed and mixed in the liquid, a liquid permeable support such as a net or a belt can be discharged to form a sheet, and the liquid can be removed by drying, and among these, water can be used as a medium. The so-called wet papermaking method to be used is preferably selected.

  In the wet papermaking method, a single or mixture containing at least one of meta-type aramid short fibers and heat-resistant porous particles, or at least one of meta-type aramid short fibers, heat-resistant porous particles, aramid fibrids and fibrillated aramids In general, the aqueous slurry is fed to a paper machine and dispersed, and then dewatered, squeezed, and dried to be wound up as a sheet. As the paper machine, for example, a long paper machine, a circular paper machine, an inclined paper machine, a combination paper machine combining these, and the like can be used. In the case of production with a combination paper machine, a composite sheet composed of a plurality of paper layers can be obtained by forming and combining slurry having different blending ratios. Here, the heat-resistant porous particles are preferably added by a spray method in order to fix the heat-resistant porous particles on the thin leaf material.

  In recent years, a spray method has been proposed as a new coating method for paper and paperboard (United States Patent No. 6063449). As a spray nozzle, a one-fluid nozzle called an airless spray method or a two-fluid called air spray is used. There is a nozzle. In the one-fluid spray, the coating liquid is pressurized and sprayed at a high speed from an elliptical spray nozzle, and fine coating particles are formed by the shear stress generated when the sprayed liquid film comes into contact with the atmosphere. This is a method of depositing and generating a coating film. The two-fluid spray has two nozzles for air and coating liquid at the nozzle tip. The high-pressure air flow is applied to the coating liquid sprayed at low pressure, and the coating liquid is made fine by the impact. In this method, the shape of the coated film is controlled by the air flow for pattern adjustment. In these spray coating methods, since there is no nip during coating, there are no coating defects caused by contact between the coating surface and the coating device, and the heat-resistant porous particles are fixed to the thin leaf material. There is no need to add components such as acrylic resin, cationic fixing reinforcing agent, and polymer flocculant to the material, and electrochemical stability such as reduction in withstand voltage due to these agents remaining in the separator. The problem of occurrence does not occur.

In addition to the above components, the thin leaf material of the present invention includes other fibrous components such as polyphenylene sulfide fibers, polyether ether ketone fibers, cellulose fibers, PVA fibers, polyester fibers, arylate fibers, and liquid crystal polyester fibers. Organic fiber such as polyethylene naphthalate fiber, glass fiber, inorganic fiber glass fiber such as rock wool, asbestos and boron fiber can also be added. When these other fibrous components are added, the blending amount is desirably 50% or less based on the total weight of all the fiber components. The thin leaf material thus obtained can be improved in mechanical strength by, for example, hot pressing at a high temperature and high pressure between a pair of flat plates or between metal rolls. For example, in the case of using a metal roll, the hot pressure can be exemplified by a temperature of 50 to 400 ° C. and a linear pressure of 50 to 2000 kg / cm. It is preferable to perform high-temperature hot pressing at a temperature equal to or higher than the glass transition temperature of the type aramid. By heat-pressing at a temperature higher than the glass transition temperature of meta-aramid, the mechanical strength is improved during hot pressing between metal rolls, and after the thickness is reduced, the residual heat present in the thin leaf material when released from between the metal rolls As a result, the stress to return to the original thickness acts and the thickness increases, so that a thin leaf material having a high porosity and a low internal resistance can be produced.

  Moreover, it is also possible to simply perform pressing at room temperature without applying a heating operation. A plurality of thin leaf materials can also be laminated during hot pressing. The above hot pressing can be performed a plurality of times in an arbitrary order. In order to further increase the strength of the thin leaf material of the present invention, the thin leaf material is laminated with another separator known per se (for example, a polyolefin microporous membrane) by a method known per se (for example, the above-described hot pressing process). It can also be used.

  The thin leaf material of the present invention comprises (1) excellent properties such as heat resistance and flame retardancy, and (2) heat resistant porous particles exhibiting a high porosity and meta-aramid short fibers that are difficult to heat-melt. In addition, since the high porosity of the thin leaf material is maintained at high temperature and heat pressure, the mobility of ionic species between the electrodes is not impaired, (3) the retention function of the electrolyte derived from the void structure is excellent, and (4) meta The type aramid has excellent characteristics such as a specific gravity as small as about 1.4, and can be preferably used as a separator between conductive members of electric / electronic parts.

  Thus, according to the present invention, as described above, electric / electronic parts such as a battery, a capacitor, a fuel cell, and a solar cell manufactured using the aramid thin leaf material of the present invention as a separator between conductive members, The shielding property is high and safety is maintained, and the high void structure and its inherently high heat resistance make it possible to withstand use in a large current environment such as an electric vehicle.

Hereinafter, the present invention will be described more specifically with reference to examples. These examples are merely illustrative and are not intended to limit the contents of the present invention.

(Measuring method)
(1) Measurement of basis weight and thickness of sheet The measurement was performed according to JIS C2111.
(2) Measurement of air permeability The air permeability was measured using a Oken type air permeability meter. For a series of sheets, the longer this time, the higher the shielding between the electrodes.
(3) Measurement of internal resistance The measurement temperature was 25 ° C., and 1M lithium borofluoride ethylene carbonate / propylene carbonate (1/1 weight ratio) was used as the electrolyte for the measurement.

Reference example (raw material preparation)
Meta-type aramid short fiber (polymetaphenylene isophthalamide short fiber) made by DuPont (
Nomex (registered trademark) was cut into a length of 6 mm to obtain a papermaking material. The glass transition temperature of the meta-type aramid fiber is 275 ° C.

  A polymetaphenylene isophthalamide fibrid was produced by a method using a wet precipitator described in Japanese Patent Publication No. 35-11851. This was processed with a disaggregator and a beater.

  “Twaron 1094” manufactured by Teijin Twaron Co., Ltd. was treated with a disaggregator and a beater to obtain fibrillated aramid.

  As heat-resistant porous particles, “TMPS (registered trademark) TMPS-4.0” (average pore diameter 4.2 nm) of Taiyo Kagaku Co., Ltd. is diluted with ion-exchanged water so that the solid content concentration becomes 1%. Used as a spray solution.

Examples 1-3
(Manufacture of thin leaf materials)
The produced meta-type aramid short fibers and aramid fibrids or fibrillated aramids were dispersed in each water to prepare a slurry. This slurry was mixed so that the meta-type aramid short fibers, aramid fibrids, and fibrillated aramid had the blending ratios of the respective examples shown in Table 1, and were mixed in a tappy hand machine (cross-sectional area of 325 cm ² ). Thus, a sheet-like material was produced. Next, the diluted spray solution was introduced into a two-fluid spray device (nozzle diameter: 1 mm) so as to achieve the blending ratio of each example shown in Table 1, and after mixing gas and liquid, the pressure was 0.3 kgf / cm ^2. After spraying on the sheet-like material, drying was performed at a temperature of 100 ° C. for 30 minutes. Next, this was hot-pressed with a metal calender roll under the conditions shown in Table 1 below to obtain a thin leaf material.

  The main characteristic values of the thin leaf material thus obtained are shown in Table 1 below.

  The thin papers of Examples 1 to 3 are considered to have low internal resistance and sufficient ionic species permeability, and require large currents, such as batteries in electric vehicles, capacitors, fuel cells, solar cells, etc. It is useful as a separator between conductive members in an electronic component.

Comparative Examples 1 and 2
(Manufacture of thin leaf materials)
The prepared meta-type aramid short fibers and aramid fibrids were each dispersed in water to prepare a slurry. The slurry was mixed so that the meta-type aramid short fibers and the aramid fibrids had the blending ratios of the comparative examples shown in Table 2 below, and a sheet-like material was produced by a wet papermaking method. Next, this was hot-pressed with a metal calender roll under the conditions shown in Table 2 below to obtain a thin leaf material.

  The main characteristic values of the thin leaf material thus obtained are shown in Table 2 below.

  As shown in Table 2 above, the thin leaf material of Comparative Example 1 has a low internal resistance but a low air permeability and is considered to have insufficient shielding properties between the electrodes.

  In addition, the thin leaf material of Comparative Example 2 increased the content of fibrid that improves mechanical strength as a binder, so the value of air permeability was slightly increased, but fibrid hinders the permeability of ionic species, The internal resistance has increased. Such a thin leaf material is considered not to be useful as a separator between conductive members in electric / electronic parts such as batteries, capacitors, fuel cells, solar cells, etc. in electric vehicles, which require a large current.

Claims (11)

  A thin leaf material comprising meta-type aramid short fibers and heat-resistant porous particles.   The thin leaf material according to claim 1, further comprising at least one of aramid fibrids and fibrillated aramids.   The thin leaf material according to claim 1 or 2, wherein the content of the meta-type aramid short fibers is 30% by weight or more. The value represented by the internal resistance value (μm) / basis weight (g / m ² ) is 9 or less, and the internal resistance value is expressed by the following formula (1)

(Internal resistance value) = (Electric conductivity of electrolyte) / {(Electricity when electrolyte is injected into separator
Air conductivity) × (Separator thickness)} Formula (1)

In the formula, (electrical conductivity when the electrolyte is injected into the separator) is the electric conductivity calculated from the measured AC impedance, sandwiched between the two electrodes with the electrolyte injected into the separator.
The thin leaf material according to any one of claims 1 to 3, which has a value represented by:   Meta type aramid short fiber is made into a sheet by wet papermaking method, heat resistant porous particles are added by fluid spray method at any point in the process, and the resulting sheet is placed between a pair of metal rolls and the glass transition of meta type aramid The method for producing a thin leaf material according to claim 1, wherein high-temperature hot pressing is performed at a temperature higher than the temperature.   Meta-type aramid short fibers and at least one of aramid fibrids and fibrillated aramids are mixed in water and formed into a sheet by wet papermaking. Heat-resistant porous particles are formed by fluid spraying at any point in the process. The thin sheet according to any one of claims 2 to 4, wherein the thin sheet is added and subjected to high-temperature hot pressing at a temperature equal to or higher than the glass transition temperature of the meta-type aramid between the pair of metal rolls. A method of manufacturing the material.   The electrical / electronic component which uses the thin leaf material of any one of Claims 1-4 as a separator between electrically conductive members.   A battery comprising the thin leaf material according to any one of claims 1 to 4 as a separator between conductive members.   A capacitor formed by using the thin leaf material according to claim 1 as a separator between conductive members.   The fuel cell formed by using the thin leaf material of any one of Claims 1-4 as a separator between electrically conductive members.   The solar cell formed by using the thin leaf material of any one of Claims 1-4 as a separator between electrically conductive members.