JP2006338917A - Electronic component and separator therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a separator for electronic components of excellent mechanical strength, dimensional stability, and heat resistance which is easily made into a thin film, and to provide electronic components which can use the separator for electronic components to be of high capacitance and functionality. <P>SOLUTION: The separator for electronic components consists of a porous film comprising communication holes. The porous film is formed from a resin material containing a synthetic resin of which glass transition point is 180°C or higher or melting point is 200°C or higher, and vinylidene fluoride resin whose melting point is less than 180°C; and filler particles which has substantially no melting point or has a melting point of 180°C or higher. The separator for electronic component is used preferably for electronic components such as a lithium ion cell, polymer lithium cell, aluminum electrolytic capacitor, or electric double layer capacitor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electronic component, in particular, a separator for an electronic component suitably used for a lithium ion battery, a polymer lithium battery, an aluminum electrolytic capacitor or an electric double layer capacitor, and an electronic component using the same.

  In recent years, regardless of industrial equipment and consumer equipment, demand for electric / electronic equipment and development of hybrid vehicles have significantly increased demand for lithium-ion secondary batteries and polymer lithium secondary batteries, which are electronic components. These electric and electronic devices are steadily increasing in capacity and functionality. Lithium ion secondary batteries, polymer lithium secondary batteries, aluminum electrolytic capacitors, and electric double layer capacitors also have higher capacities and higher functions. Is required.

  Lithium ion secondary battery and polymer lithium secondary battery are prepared by mixing an active material, lithium-containing oxide and a binder such as polyvinylidene fluoride in 1-methyl-2-pyrrolidone and forming a sheet on an aluminum current collector. A negative electrode formed by mixing a carbonaceous material capable of occluding and releasing lithium ions and a binder such as polyvinylidene fluoride in 1-methyl-2-pyrrolidone and forming a sheet on a copper current collector, polyvinylidene fluoride, In this structure, a porous electrolyte membrane made of polyethylene or the like is wound or laminated on a positive electrode, an electrolyte membrane, and a negative electrode in this order, impregnated with a driving electrolyte, and sealed with an aluminum case. In addition, an aluminum electrolytic capacitor is formed on an electrode body obtained by etching or laminating an aluminum positive electrode foil subjected to a chemical conversion treatment to form a dielectric film and an etched aluminum negative electrode foil via a separator. It is impregnated with an electrolyte for driving, sealed with an aluminum case and a sealing body, and has a structure in which a positive electrode lead and a negative electrode lead are passed through the sealing body and pulled out so as not to be short-circuited. An electric double layer capacitor is a mixture of activated carbon, a conductive agent and a binder, which is attached to both surfaces of an aluminum positive electrode and a negative electrode, and wound or laminated with a separator on the electrode body. It is impregnated and packed with an aluminum case and a sealing body, and has a structure in which a positive electrode lead and a negative electrode lead are passed through the sealing body and pulled out so as not to be short-circuited.

  Conventionally, polyolefin-based porous membranes and non-woven fabrics have been used as separators for lithium ion batteries or polymer lithium batteries, and paper and cellulose fibers made of cellulose pulp have been used as separators for aluminum electrolytic capacitors and electric double layer capacitors. Nonwoven fabric made of polyester fiber, acrylic fiber or the like is used.

  By the way, attempts to increase the capacity and function of electronic components as described above have been advanced. When the capacity is increased, abnormal heat generation is increased during abnormal charging, and therefore a separator having heat resistance to withstand high temperatures, high mechanical strength, and excellent heat-resistant dimensional stability is required. On the other hand, improvement of rapid charge / discharge characteristics, improvement of high output characteristics, etc. have been attempted as one of the measures for enhancing the functionality of electronic components, and separators are strongly required to be thin and improve uniformity. Yes. In the conventional separator as described above, not only the heat resistance is insufficient, but also when the film is thinned, through-holes are likely to exist, and the mechanical strength is reduced, resulting in an internal short circuit between the electrodes. There is a problem that the reliability is lowered due to occurrence of a portion where the uniformity is insufficient and ion movement or electron movement is locally concentrated. In the case of thinning the film, as a method of ensuring the mechanical strength, the porosity may be lowered. However, in that case, the internal resistance is increased, and the demand for higher functionality cannot be satisfied.

In response to the demand for such a separator, for example, a porous film made of a heat-resistant resin as described in Patent Document 1 has been studied. When making a heat resistant resin porous, a phase change method (microphase separation method) is usually used. The principle of the phase conversion method is based on the phase separation phenomenon of the polymer solution. It solidifies by causing gelation or phase separation from the solution state. In general, the evaporation method is called a dry method, and the non-solvent contact method is called a wet method. Such a phase separation phenomenon generally proceeds asymmetrically in many cases. That is, the concentration change due to evaporation gradually occurs from the solution surface toward the inside, and the change in the solvent composition due to non-solvent contact also proceeds from the contact interface between the polymer solution phase and the non-solvent toward the inside. Therefore, since the progress of phase separation differs between the solution surface or contact interface and the inside of the solution, an asymmetric porous structure is formed. The porous film formed by the phase conversion method has a hierarchical structure by decreasing the pore diameter as it approaches the surface layer of the film, or by forming a dense layer (skin layer) having no pores. Become a film. Such a phenomenon is particularly prominent in the case of making a porous material by a wet method. Such a hierarchical structure is preferably used in a separation membrane having a selective separation function such as a reverse osmosis membrane, but an electronic component in which ions or electrons move bidirectionally by repeated charging and discharging. It was a factor that deteriorated the performance of the separator for use.
JP 2003-313356 A

  An object of the present invention is to provide an electronic component separator that solves the above-described problems in an electronic component separator, is easy to be thinned, and has excellent mechanical strength, dimensional stability, and heat resistance. is there. Furthermore, the objective of this invention is providing the high capacity | capacitance and the highly functional electronic component using the said separator for electronic components.

  An electronic component separator according to the present invention for achieving the above-described object comprises a porous film having communication holes, and the porous film comprises a synthetic resin having a glass transition point of 180 ° C. or higher or a melting point of 200 ° C. or higher. It is characterized by comprising a resin material containing a vinylidene fluoride resin having a melting point of less than 180 ° C. and filler particles having substantially no melting point or a melting point of 180 ° C. or higher.

In the present invention, the synthetic resin having a glass transition point of 180 ° C. or higher or a melting point of 200 ° C. or higher is any one of polyamide, polyamideimide, polyimide, polysulfone, polyethersulfone, polyphenylsulfone, and polyacrylonitrile, or those 2 A mixture of seeds or more is preferred. Moreover, it is preferable that content of the said filler particle is 25 to 85 weight% with respect to the total solid of a porous membrane. Moreover, it is preferable that the primary average particle diameter of a filler particle is 1 / 100-1 / 2 of the film thickness of a porous membrane. Furthermore, the filler particles are preferably electrically insulating inorganic particles or polytetrafluoroethylene particles. Moreover, it is preferable that content of the said vinylidene fluoride resin is 0.5 to 30 weight% with respect to the total solid of a porous membrane. In the separator of the present invention, the air permeability of the porous membrane is preferably 0.1 to 100 seconds / 100 ml, and the film thickness is preferably 1 to 50 μm.
The electronic component of the present invention has a positive electrode and a negative electrode, the electronic component separator is disposed between them, and the electronic component separator is impregnated with an electrolyte. .

  The separator for electronic parts according to the present invention can be easily thinned, has excellent mechanical strength, dimensional stability and heat resistance, and has very good wettability and retainability with respect to an electrolytic solution, and has various practical characteristics. It is possible to obtain high reliability while maintaining extremely low thermal shrinkage even during heating. Therefore, the separator for electronic parts of the present invention is suitably used for electronic parts such as lithium ion batteries, polymer lithium batteries, aluminum electrolytic capacitors, electric double layer capacitors, and redox capacitors. In particular, it can be suitably used for large electronic components that require heat resistance, and it is possible to achieve high performance and high functionality of the electronic components.

  The resin material constituting the separator for electronic parts of the present invention includes a synthetic resin having a glass transition point of 180 ° C. or higher or a melting point of 200 ° C. or higher and a vinylidene fluoride resin having a melting point of less than 180 ° C. Specific examples of synthetic resins having a glass transition point of 180 ° C. or higher or a melting point of 200 ° C. or higher include polyamide, polyamideimide, polyimide, polysulfone, polyethersulfone, polyphenylsulfone, polyacrylonitrile, polyetheretherketone, and polyphenylene. Examples thereof include those composed of at least one of sulfide and polytetrafluoroethylene. These synthetic resins can be produced using known techniques. Since the heat resistance, dimensional stability, and mechanical strength of the separator of the present invention depend on these heat-resistant synthetic resins, the characteristics are extremely important. In particular, the glass transition point or the melting point is important in terms of heat resistance. It becomes a characteristic. If the glass transition point of the synthetic resin is less than 180 ° C. or the melting point is less than 200 ° C., the electronic component is likely to undergo dimensional change and deformation when heated to a high temperature of 180 ° C. or higher. Since it leads to deterioration of component performance, it is not preferable. Depending on the production of the electronic component and the environment in which the electronic component is used, the synthetic resin may be exposed to a high temperature environment of 200 ° C. or higher, and the synthetic resin preferably has a glass transition point of 200 ° C. or higher or a melting point of 220 ° C. or higher. The glass transition point can be measured and analyzed by the method described in JIS K7121.

  Moreover, when manufacturing the separator for electronic components, the resin material is used by being dissolved or dispersed in a solvent. In this case, the synthetic resin is preferably a synthetic resin that dissolves in a solvent in order to make the mechanical strength and uniformity of the porous membrane better. Polyamideimide, polyimide, polysulfone, polyethersulfone, polyphenylsulfone And any one of polyacrylonitrile or a mixture of two or more thereof. Of these, polyamideimide and polyphenylsulfone having excellent mechanical strength are particularly preferably used.

  On the other hand, it is also possible to contain a synthetic resin having a glass transition point of less than 180 ° C. within a range that does not impair mechanical strength, dimensional stability, and heat resistance. Inclusion of such a synthetic resin can improve the wettability, retainability, and flexibility of the electrolyte used in the electronic component. In such a case, the content is preferably in the range of 20% by weight or less of the total resin components. If the added amount exceeds 20% by weight, the heat resistance may be lowered, and the object of the present invention cannot be achieved.

  The separator for electronic parts of the present invention needs to contain a vinylidene fluoride resin having a melting point of less than 180 ° C., and preferably has a melting point of 80 ° C. or more, more preferably 120 ° C. or more. . The vinylidene fluoride resin is electrochemically stable and has a sufficient potential at the interelectrode potential when assembled into an electronic component. In addition, it has good wettability with respect to carbonate solvents, ether solvents, lactone solvents, and amide solvents used in electronic components, and is necessary for the purpose of improving the wettability of the separator of the present invention. It will be. Specific examples of the vinylidene fluoride resin having a melting point of less than 180 ° C. are selected from the group consisting of homopolymer (polyvinylidene fluoride) made of vinylidene fluoride alone, ethylene tetrafluoride, hexafluoropropylene, and ethylene. And a copolymer of one or more of the above and vinylidene fluoride. These copolymers can be used alone or in combination. In order to improve heat resistance, it is preferable to use polyvinylidene fluoride, but in order to further improve wettability, it is preferable to use a copolymer. In particular, as a vinylidene fluoride resin having both heat resistance and wettability, a terpolymer of ethylene tetrafluoride, propylene hexafluoride, and vinylidene fluoride is preferable.

  In this invention, it is preferable that content of the said vinylidene fluoride resin is 0.5 to 20 weight% with respect to the total solid of a porous membrane. If the content is less than 0.5% by weight, the effect on wettability and retention cannot be obtained, which is not preferable. When the content is more than 20% by weight, since the melting point of the vinylidene fluoride resin is less than 180 ° C., the heat resistance of the separator of the present invention is impaired, which is not preferable. In order to achieve both high heat resistance and high wettability, the more preferable content is 1 to 10% by weight, and even more preferably 2 to 5% by weight.

  The separator for electronic parts of the present invention is composed of a porous film having a communication hole substantially having no shielding structure, and it is necessary to contain filler particles in order to obtain such a porous film. The presence of the filler particles has an effect of preventing formation of a dense layer (skin layer) having no pores when the separator for electronic parts of the present invention is produced, that is, when the porous structure is formed. The reason for this is not clear, but it is considered that the solvent is unevenly distributed between the filler particles uniformly dispersed in the resin solution and the resin interface, and the porosity is preferentially advanced around the filler particles. The filler particles are presumably because the phase separation state tends to be uniform in the coating thickness direction because the filler particles are uniformly dispersed on the surface and inside of the applied paint. By preventing the formation of the dense layer, a porous structure can be formed which communicates from one surface of the porous membrane to the other surface, and does not hinder ion conduction and electron conduction inside the electronic component.

  The filler particles used in the electronic component separator of the present invention must have a melting point of 180 ° C. or higher or substantially no melting point. When the melting point is lower than 180 ° C., it may be melted by heat at the time of heating to block the pores of the porous structure. Further, in the case of a material that is easily dissolved or gelled in the electrolytic solution, clogging is likely to occur, which may reduce the performance of the electronic component, which is not preferable. Further, if the filler particles are conductive, they cannot be used because they cause an internal short circuit. Accordingly, the filler particles need to be electrically insulating. There are no particular limitations on the shape of the filler particles, and amorphous fillers, plate-like fillers, needle-like fillers, and spherical fillers are used, but spherical fillers are most suitable for uniform dispersion in the porous membrane. Specific materials for the filler particles include, for example, electrically insulating inorganic particles such as natural silica, synthetic silica, alumina, titanium oxide, and glass, polytetrafluoroethylene, crosslinked acrylic resin, benzoguanamine resin, crosslinked polyurethane, and crosslinked styrene resin. And organic particles such as melamine resin. Of these, electrically insulating inorganic particles or polytetrafluoroethylene particles having excellent chemical resistance, heat resistance and dispersibility are preferably used. The melting point can be measured by the method described in JIS K7121.

  In the present invention, the content of the filler particles is preferably in the range of 25 to 85% by weight with respect to the total solid content of the porous membrane. As the content increases, it becomes possible to prevent the formation of a dense layer. However, since the mechanical strength of the porous film is lowered, it is preferably 85% by weight or less. On the other hand, if the content is less than 25% by weight, the effect of hindering the formation of the dense layer is reduced, so that a material satisfying the air permeability described later cannot be obtained. The optimum content that satisfies both mechanical strength and air permeability is in the range of 40 to 70% by weight.

  The primary average particle diameter of the filler particles is 1/100 to 1/2 of the film thickness of the porous film, and the maximum particle diameter is preferably equal to or less than the film thickness. When the primary average particle diameter is larger than the above range, particles protruding in a protruding shape are likely to be present on the surface of the porous film, and the film thickness may be uneven, which is not preferable. The most preferable primary average particle diameter is 1/100 to 1/10 of the film thickness, and the primary average particle diameter of 1/10 or less can sufficiently prevent the formation of a dense layer. The diameter is not always necessary. On the other hand, when the particle diameter is smaller than 1/100, the effect of preventing the formation of the dense layer is lost, and the air permeability deteriorates. A preferred specific range of the primary average particle diameter of the filler particles is 1 to 10 μm. In addition, the said primary average particle diameter is a volume average particle diameter calculated | required from the particle size distribution measurement by the laser diffraction diffusion method (microtrack method).

  The separator for electronic parts of the present invention is composed of a porous film made of the above resin material, filler particles, and vinylidene fluoride resin. The porous membrane has a large number of continuous pores, and the average pore diameter of the pores by the bubble point method is preferably 0.1 to 5 μm, more preferably 0.5 to 3 μm. Range. When the average pore diameter is less than 0.1 μm, ion conductivity may be inhibited, and the impregnation property of the electrolytic solution tends to be lowered, which is not preferable. Further, when the average pore diameter is larger than 5 μm, it is not preferable because a problem such as an internal short circuit occurs when the separator is thinned.

The porosity of the porous film is a measure of the porosity. The porosity of the separator of the present invention is preferably in the range of 30 to 90%. If the porosity is too low, the internal resistance increases, leading to deterioration of the performance of the electronic component. On the other hand, if the porosity is too high, the mechanical strength is lowered and it is difficult to achieve the object of the present invention. A more preferable range is 50 to 80%, and if it is within this range, the separator of the present invention is a separator having sufficient mechanical strength, low internal resistance, and excellent ion conductivity and electron conductivity. .
The porosity here is calculated | required by following Formula using basis weight M (g / cm < ² >), thickness T (micrometer), and density D (g / cm < ³ >).
Porosity (%) = [1- (M / T) / D] × 100

  As one for evaluating the connectivity of the pores of the porous membrane, there is an air permeability measured by a Gurley type air permeability measuring apparatus described in JIS P 8117. The lower the air permeability value, the better the air permeability. In the electronic component separator, the air permeability value is preferably low. In the electronic component separator, the lower the value of the air permeability, the better the ion conductivity. The separator for electronic parts of the present invention preferably has an air permeability of 0.1 to 100 seconds / 100 ml. When the air permeability is greater than 100 seconds / 100 ml, ion migration is inhibited, that is, ion conductivity is deteriorated, impedance is increased, and electronic component performance is also deteriorated. However, if it is smaller than 0.1 sec / 100 ml, on the other hand, although the ion conductivity is good, a minute short circuit between the electrodes is likely to occur, and the electronic component performance is deteriorated as in the above case.

  The separator for electronic parts of the present invention preferably has a thickness in the range of 1 to 50 μm. The separator for electronic parts of the present invention has excellent mechanical strength that is practically acceptable even if it is a thin film of 50 μm or less, and a film thickness larger than that is not necessary. On the other hand, when the film thickness is less than 1 μm, the mechanical strength is lowered, and the handleability is also deteriorated. A more preferable film thickness of the separator of the present invention is 3 to 30 μm, and most preferably 5 to 15 μm. The separator of the present invention has a sufficiently high mechanical strength even at a film thickness of 15 μm or less, and the internal resistance is reduced by thinning, so that an excellent electronic component having no practical problem can be obtained. .

  As described above, the separator for electronic parts of the present invention, which has high heat resistance, excellent air permeability, high mechanical strength and can be thinned, has low internal resistance and high capacity when used in electronic parts. Therefore, it can be suitably used for lithium ion batteries, polymer lithium batteries, aluminum electrolytic capacitors, or electric double layer capacitors.

Next, the manufacturing method of the separator of the present invention will be described. The production method is not limited to this, and the separator of the present invention can be produced by other production methods.
First, a resin material including a synthetic resin having a glass transition point of 180 ° C. or higher or a melting point of 200 ° C. or higher and a vinylidene fluoride resin having a melting point of less than 180 ° C., a melting point of 180 ° C. or higher, or a substantial melting point Applying a coating material containing filler particles that do not have, a solvent that substantially dissolves the resin material (good solvent), and a solvent that does not substantially dissolve the resin material (poor solvent) to the substrate, and then drying. To form a porous film, and then the substrate is removed to obtain a separator. Although the good solvent used for a coating here does not have a restriction | limiting in particular, If it is a solvent which can melt | dissolve the said resin material, it can use suitably. Principal examples include amide solvents such as 1-methyl-2pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, and ketone solvents such as 2-butanone and cyclohexanone. The poor solvent that does not dissolve the resin material is not particularly limited, and may be used after confirming the solubility of the resin material. Since the type, properties, physical characteristics, and addition amount of the poor solvent greatly affect the pore diameter, porosity, etc. of the porous membrane, it is preferably selected as appropriate under the following conditions. As the poor solvent has a higher boiling point than the good solvent, the porosity of the porous film tends to increase. Further, the larger the amount added, the higher the porosity. However, if the amount is too large, the viscosity of the coating becomes too high, and the handleability is poor and the productivity is deteriorated. A preferable poor solvent has a boiling point that is 10 to 20 ° C. higher than that of the good solvent, and its addition amount is in the range of 10 to 30% by weight based on the total solvent. Examples of the poor solvent that can be selected when the above good solvent is used include, for example, glycols such as ethylene glycol, diethylene glycol, and glycerin, alcohols such as octanol and decanol, aliphatic hydrocarbons such as nonane and decane, and phthalic acid. Examples include esters such as dibutyl, but are not limited thereto. When preparing the coating material, there is no particular limitation on the method of adding the resin material, filler particles, and solvent, but the coating material dissolves the resin material in a good solvent, then mixes and disperses the filler particles, and adds the poor solvent. Can also be easily prepared.

  Next, the obtained coating material is apply | coated on a base material. Any substrate can be used as long as it is smooth, and examples thereof include resin films such as polyolefin films and polyester films, metal foils such as aluminum, and various glasses. These base materials may be subjected to surface treatment such as mold release treatment or easy adhesion treatment, and may be appropriately selected depending on the coating method. Examples of the coating method include a dip coating method, a spray coating method, a roll coating method, a doctor blade method, a gravure coating method, a screen printing method, and a coating or casting method. After being coated on the base material, the porous film is formed on the base material by drying in the range of room temperature to about 180 ° C. and evaporating the solvent. The drying method may be under reduced pressure, normal pressure, or air drying. By separating the porous film from the substrate, the electronic component separator of the present invention can be obtained.

Next, an electronic component using the separator of the present invention will be described.
For example, when manufacturing a cylindrical polymer lithium secondary battery as an electronic component, the separator of the present invention is sandwiched between two tape-shaped electrodes of a positive electrode and a negative electrode, and wound while being stacked by a winding machine. Then, it is put into a cylindrical aluminum or stainless steel vessel, and an electrolyte is injected. The lead wire can be taken out from each terminal of the positive electrode and the negative electrode and sealed. As the positive electrode, an active material such as lithium cobaltate and lithium manganate and a conductive auxiliary agent such as acetylene black are dispersed in a binder resin solution such as an N-methylpyrrolidone solution of polyvinylidene fluoride and slurried. Those coated on a positive electrode current collector made of aluminum foil can be used. As said negative electrode, what apply | coated the thing which disperse | distributed natural graphite in the binder resin solution similar to the above on the negative electrode electrical power collector which consists of copper foil can be used. As the electrolytic solution, a solution obtained by adding lithium hexafluorophosphate to a mixed solvent of ethylene carbonate and dimethyl carbonate can be used.

  In addition, for example, when manufacturing a coin-type cell of an electric double layer capacitor using the separator of the present invention, a laminate is formed by sandwiching the circular separator of the present invention between two circular electrodes. Place in a coin-shaped vessel made of aluminum or stainless steel. After injecting the electrolytic solution, it can be manufactured by sealing with a coin-shaped upper lid. The two electrodes have a structure in contact with the upper lid and the lower lid (bottom of the vessel) inside the vessel, and each lid serves as a terminal. Here, for example, an activated carbon electrode or the like can be used as the electrode, and a tetraethylammonium salt of boron tetrafluoride or the like can be used as the electrolytic solution.

  Below, the separator for electronic parts of the present invention will be described with reference to examples. However, the present invention is not limited to these examples.

  After dissolving 47 parts by weight of polyamideimide having a glass transition point of 300 ° C. and 3 parts by weight of polyvinylidene fluoride having a melting point of 174 ° C. in 400 parts by weight of N, N-dimethylacetamide as a good solvent, ethylene glycol as a poor solvent As a filler particle, 50 parts by weight of polytetrafluoroethylene particles having a melting point of 327 ° C. and a primary average particle diameter of 0.25 μm were added and mixed to prepare a paint. Next, the coating material was applied onto a resin film substrate made of polyethylene terephthalate by a casting method and dried in an air blow dryer at 80 ° C. to completely evaporate the solvent. Thereafter, the resin film substrate was peeled off to obtain the electronic component separator of the present invention. The thickness of the obtained separator was 20 μm.

  An electronic component separator of the present invention was obtained in the same manner as in Example 1 except that the coating amount was adjusted. The obtained separator had a thickness of 12 μm.

  After dissolving 40 parts by weight of polyamideimide having a glass transition point of 300 ° C. and 10 parts by weight of polyvinylidene fluoride having a melting point of 174 ° C. in 400 parts by weight of N, N-dimethylacetamide as a good solvent, ethylene glycol is used as a poor solvent. As a filler particle, 50 parts by weight of polytetrafluoroethylene particles having a melting point of 327 ° C. and a primary average particle diameter of 0.25 μm were added and mixed to prepare a paint. Next, the coating material was applied onto a resin film substrate made of polyethylene terephthalate by a casting method and dried in an air blow dryer at 80 ° C. to completely evaporate the solvent. Thereafter, the resin film substrate was peeled off to obtain the electronic component separator of the present invention. The thickness of the obtained separator was 20 μm.

  45 parts by weight of polyamideimide having a glass transition point of 300 ° C. and 5 parts by weight of vinylidene fluoride-hexafluoropropylene copolymer having a melting point of 124 ° C. are dissolved in 400 parts by weight of a good solvent N, N-dimethylacetamide. Thereafter, ethylene glycol as a poor solvent and 50 parts by weight of polytetrafluoroethylene particles having a melting point of 327 ° C. and a primary average particle diameter of 0.25 μm as additive particles were added and mixed to prepare a coating material. Next, the coating material was applied onto a resin film substrate made of polyethylene terephthalate by a casting method and dried in an air blow dryer at 80 ° C. to completely evaporate the solvent. Thereafter, the resin film substrate was peeled off to obtain the electronic component separator of the present invention. The thickness of the obtained separator was 20 μm.

  45 parts by weight of polyamideimide having a glass transition point of 300 ° C. and 5 parts by weight of vinylidene fluoride-propylene hexafluoride-tetrafluoroethylene copolymer having a melting point of 124 ° C. are used as a good solvent, N, N-dimethylacetamide. After being dissolved in 400 parts by weight, ethylene glycol as a poor solvent and 50 parts by weight of polytetrafluoroethylene particles having a melting point of 327 ° C. and a primary average particle diameter of 0.25 μm are added and mixed as a filler particle. Prepared. Next, the coating material was applied onto a resin film substrate made of polyethylene terephthalate by a casting method and dried in an air blow dryer at 80 ° C. to completely evaporate the solvent. Thereafter, the resin film substrate was peeled off to obtain the electronic component separator of the present invention. The thickness of the obtained separator was 20 μm.

  A separator for electronic parts of the present invention was obtained in the same manner as in Example 2 except that polyamide having a melting point of 235 ° C. was used as the heat resistant polymer material. The thickness of the obtained separator was 20 μm.

  After dissolving 47 parts by weight of polyamideimide having a glass transition point of 300 ° C. and 3 parts by weight of polyvinylidene fluoride having a melting point of 174 ° C. in 400 parts by weight of N, N-dimethylacetamide as a good solvent, ethylene glycol as a poor solvent Then, 50 parts by weight of silica particles having a primary average particle diameter of 1 μm having substantially no melting point as filler particles were added and mixed to prepare a coating material. Next, the coating material was applied onto a resin film substrate made of polyethylene terephthalate by a casting method and dried in an air blow dryer at 80 ° C. to completely evaporate the solvent. Thereafter, the resin film substrate was peeled off to obtain the electronic component separator of the present invention. The thickness of the obtained separator was 20 μm.

[Comparative Example 1]
A polyethylene stretched porous film that is currently widely used in lithium ion secondary batteries was used as a comparative separator. The film thickness of this polyethylene separator was 20 μm.

[Comparative Example 2]
A paper separator made of cellulose pulp, which is currently widely used for electric double layer capacitors, was used as a comparative separator. The film thickness of this paper separator was 30 μm.

[Comparative Example 3]
A polyamideimide having a glass transition point of 300 ° C. was dissolved in a good solvent N, N-dimethylacetamide, and ethylene glycol was added and mixed as a poor solvent to prepare a paint. The final solid content concentration was 10% by weight, and this paint did not contain filler particles. Next, the coating material was applied onto a resin film substrate made of polyethylene terephthalate by a casting method and dried in an air blow dryer at 80 ° C. to completely evaporate the solvent. Thereafter, the resin film substrate was peeled off to obtain a comparative separator. The thickness of the obtained separator was 25 μm.

[Comparative Example 4]
50 parts by weight of polyamideimide having a glass transition point of 300 ° C. is dissolved in 400 parts by weight of N, N-dimethylacetamide as a good solvent, ethylene glycol as a poor solvent, and a melting point of 327 ° C. as filler particles and a primary average particle diameter Was added and mixed with 50 parts by weight of polytetrafluoroethylene particles having a particle size of 0.25 μm to prepare a coating material. Next, the coating material was applied onto a resin film substrate made of polyethylene terephthalate by a casting method and dried in an air blow dryer at 80 ° C. to completely evaporate the solvent. Then, the film base material used for the base material was peeled off to obtain a comparative separator. The thickness of the obtained separator was 20 μm.

  The following evaluation was performed on the separators obtained in Examples 1 to 7 and Comparative Examples 1 to 4, and the characteristics as the separator for electronic parts were evaluated. In addition, Table 1 summarizes the types of resin materials used for the production of the porous membrane, the types of filler particles, the primary average particle diameter, the content in the total solid content, and the thickness of the porous membrane. In Table 1, PTFE is polytetrafluoroethylene (polytetrafluoroethylene), PVdF is polyvinylidene fluoride, PVdF-HFP is vinylidene fluoride-hexafluoropropylene copolymer, PVdF- HFP-TFE means a vinylidene fluoride-propylene hexafluoride-tetrafluoroethylene copolymer, respectively.

<Air permeability>
About the separator obtained in Examples 1-7 and Comparative Examples 1-4, the air permeability was measured with the Gurley type densometer B type made from Yasuda Seiki Co., Ltd. based on JISP8117. The results are shown in Table 2.

  From the above results, it is confirmed that the separators for electronic parts of the present invention all have low air permeability and have uniform pores and communication holes in the thickness direction of the porous membrane. It was done. On the other hand, it was confirmed that the separator of Comparative Example 3 has high air permeability, that is, has a dense layer inside the porous membrane.

<Heat-resistant dimensional stability>
An aluminum bat that is horizontally placed after sandwiching a test piece obtained by cutting a separator of Examples and Comparative Examples into a square of 5 × 5 cm between two glass plates having a size of 10 × 10 cm and a thickness of 5 mm. And left in an oven at 200 ° C. for 24 hours to examine changes in area due to heat. The area change was evaluated as area change rate (100%) = (area after test / area before test: 25 cm ² ) × 100, and used as an index of heat-resistant dimensional stability. The results are shown in Table 3.

  From the above results, it was confirmed that the separator for electronic parts of the present invention using a heat-resistant resin material is at least equal to or better than that of Comparative Example 2 in terms of heat-resistant dimensional stability. It was done. On the other hand, the separator of Comparative Example 1 using no heat-resistant resin material was inferior in heat-resistant dimensional stability, completely dissolved at 200 ° C., and did not maintain its shape at all.

<Ion conductivity of assembled electronic components>
About the separator of Examples 1-7 and Comparative Examples 1-4, the electric double layer capacitor was assembled using the electrode, and the coin-type cell was produced. In the production of the coin-type cell, an activated carbon electrode (made by Hosen Co., Ltd.) for an electric double layer capacitor was used as an electrode. Also, were used for the propylene carbonate as an electrolyte, was dissolved at a 1 mol / L of _{(C 2 H 5) 4 NBF} 4.

  About the produced coin-type cell, the ionic conductivity in a 20 degreeC environment was measured with the alternating current impedance measuring method. Furthermore, a coin-type cell was similarly produced for the test piece after the heat treatment carried out in the evaluation of the heat-resistant dimensional stability, and the ionic conductivity was evaluated. In addition, the solar conductivity company make: SI1287-1255B was used for the measurement of ion conductivity. Table 4 shows the obtained results.

  From the above results, the separator for electronic parts of the present invention shows high ionic conductivity even after being exposed to a high temperature of 200 ° C., and all have superior ionic conductivity compared to the separators of Comparative Examples 1 to 4. It was confirmed that In addition, since the separator of the comparative example 1 had low heat resistance, it could not endure use in a high temperature environment.

  Summarizing the above four types of evaluation results, the separator for electronic parts of the present invention has uniform communication holes in the thickness direction of the porous membrane, and satisfies all of heat resistance and ion conductivity at a high level. It is clear that it is. Therefore, the separator for electronic parts of the present invention can sufficiently meet the recent demand for higher capacity and higher functionality of electronic parts.

Claims (9)

  A porous film having a communication hole, the porous film comprising a synthetic resin having a glass transition point of 180 ° C. or higher or a melting point of 200 ° C. or higher and a vinylidene fluoride resin having a melting point of less than 180 ° C., and substantially A separator for electronic parts, characterized by comprising filler particles having no melting point or having a melting point of 180 ° C. or higher.   The synthetic resin having a glass transition point of 180 ° C. or higher or a melting point of 200 ° C. or higher is any one of polyamide, polyamideimide, polyimide, polysulfone, polyethersulfone, polyphenylsulfone, and polyacrylonitrile, or two or more thereof. The separator for electronic parts according to claim 1, wherein the separator is an electronic component.   3. The electronic component separator according to claim 1, wherein a content of the filler particles is 25 to 85 wt% with respect to a total solid content of the porous membrane.   4. The electronic component separator according to claim 1, wherein a primary average particle diameter of the filler particles is 1/100 to 1/2 of a film thickness of the porous film. 5. .   The separator for an electronic component according to any one of claims 1 to 4, wherein the filler particles are electrically insulating inorganic particles or polytetrafluoroethylene particles.   The content of the vinylidene fluoride resin is 0.5% by weight to 20% by weight with respect to the total solid content of the porous film, according to any one of claims 1 to 5. Separator for electronic parts.   The separator for an electronic component according to any one of claims 1 to 6, wherein the air permeability of the porous membrane is 0.1 to 100 seconds / 100 ml.   The separator for an electronic component according to any one of claims 1 to 7, wherein the porous film has a thickness of 1 to 50 µm.   It has a positive electrode and a negative electrode, The electronic component separator of any one of Claim 1 thru | or 8 is arrange | positioned among them, Electrolyte solution is impregnated in this electronic component separator Electronic parts characterized by