Aramid thin sheet material and electrical/electronic parts using the same

Abstract

The invention provides an aramid thin sheet material comprising two components of aramid staple fibers and fibrillated aramid, or said two components and aramid fibrid, in particular, characterized by satisfying both of the following expressions (1) and (2): [internal resistance] (μm)≦250 (μm)  expression (1) [Oken-type gas permeability] (sec / 100 cm3)≧0.5 (sec / 100 cm3)  expression (2) wherein the [internal resistance] is a resistance value calculated by the following expression (3): [internal⁢ ⁢resistance⁢ ]⁢(μ⁢ ⁢m)=[electrical⁢ ⁢conductivity⁢ of⁢ ⁢electrolyic⁢ ⁢solution][electrical⁢ ⁢conductivityof⁢ ⁢electrolyticsolution⁢-⁢injected⁢ thin⁢ ⁢sheet⁢ ⁢material]×[thickness⁢ of⁢ ⁢the⁢  ⁢thinsheet ⁢material]⁢(μ⁢ ⁢m).expression⁢ ⁢(3)

Description

TECHNICAL FIELD [0001] This invention relates to aramid thin sheet material useful as separators for separating conductive members in electrical / electronic parts to allow passage of ionic species such as electrolyte or ion; and also to electrical / electronic parts using the separators. In particular, the invention relates to aramid thin sheet material useful for separator panels between electrodes in condensers, capacitors, batteries and the like which use lithium ion, sodium ion, ammonium ion, hydrogen ion and the like as a carrier of electric current. BACKGROUND ART [0002] As symbolized by the recent progress in portable communication devices or high-speed information processors, reduction in size and weight and advance in technical performance of electronic instruments are splendid. Above all, more expectation is placed on small size, light weight, and higher capacity and performance electric batteries and condensers which can withstand storage over prolonged period. Their applica...

AI Technical Summary

Benefits of technology

[0031] In the present invention, freeness of the aramid fibrid after the beating treatment preferably lies within a range of 10-300 cm3, in particular, 10-80 cm3 (Canadian freeness). With fibrid having the freeness more than the specified range, the aramid thin sheet material formed therefrom is liable to have reduced strength. On the other hand, attempts to achieve freeness less than 10 cm3 reduce utilization efficiency of mechanical power projected and often decrease processing quantity per unit time. Furthermore, because such excessively advances pulverization of the fibrid, it is apt to invite deterioration in “binder” function. Hence, no substantial merit is found in attempts to obtain freeness less than 10 cm3.

[0050] The aramid thin sheet material of the present invention can be used as laminated with known other separator (e.g., polyolefine microporous membrane) by per se known means (e.g., above hot-press processing) for further increasing its strength.

[0052] Thus, electrical / electronic parts such as condensers, capacitors and batteries manufactured with use of the aramid thin sheet material of the present invention as separator panels between electrically conductive members show high shielding property between electrodes and maintain high safety. Also due to the material's inherently high heat resistance, the electrical / electronic parts achieve the effect of withstanding the use under heavy current environment of hybrid cars, electric cars and the like. (Internal Resistance)

Problems solved by technology

Such micro-porous sheeting and non-woven fabrics possess favorable physical properties for the separator, but do not necessarily fully meet recent demands for condensers, capacitors or batteries of still higher capacity and power output required for electric cars.

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