Yuasa Battery Co., Ltd.

Japan Atomic Energy Research Institute

Yuasa Corporation

Shiro Tanso

Kazuo Murata

Takanobu Sugo

Isao Ishigaki

Sueo Machi

Keizi Senoo

Junzo Yamao

Tamiyuki Eguchi

Toshio Okada

Nobuo Hayashi

Naoki Murakami

Seiji Okuda

An immersion type membrane filter apparatusis intended for obtaining filtrate by filtrating a fluid to be processed stored within a storage bathand primarily includes a filtration membrane moduleand an air bubbles supply devicedisposed therebelow. The filtration membrane modulehas numerous tubular membraneshaving on the inner surfaces thereof the function of filtrating a fluid to be processed packed within a cylindrical housing vesselhaving a discharge portfor filtrate. The tubular membranesare held in an opened state at both the ends of the housing vessel. The filtration membrane moduleis soaked in a fluid to be processed in such a way that the tubular membranesare opened in the vertical direction. When air bubbles are supplied to the filtration membrane modulefrom an air bubbles supply device, the fluid to be processed flows through the tubular membranesfrom the down side upwards to naturally circulate within the storage bath. Part of the fluid to be processed is filtrated by passing through the tubular membranesfrom the inside to the outside. As a result, the filtrate thus obtained flows out via the discharge portto a filtrate discharge pathway

Immersion type membrane filter

A method of producing a hydrophilic membrane from a polyethylene base film by first irradiating the film with ionizing radiation in air or an oxygen atmosphere and then grafting acrylic acid and/or methacrylic acid onto the irradiated film at low temperatures.

Method of producing a hydrophilic membrane from a polyethylene base film

A novel process for the production of a separator for use in a cell to prevent the short-circuiting of positive active material and negative active material comprises irradiating a polyolefin film 150 .mu.m or less thick with ionizing radiation at a dose rate of 5.times.10.sup.4 -10.sup.7 rads/sec. to give a total dose of 1 Mrad or more, contacting the irradiated film with an aqueous solution of a terminally unsaturated monomer such as acrylic acid, methacrylic acid and the like at a temperature of 10.degree. C.-60.degree. C. to thereby cause grafting of the monomer onto the polyolefin film before the grafted polymer film is treated with an aqueous alkaline solution to finally obtain the separator for use in a cell, which is substantially improved in that it shows low electrical resistance and is excellent both in its acid resistance and mechanical strength.

Process for production of separators for use in cells

There is disclosed a novel cell separator made of a grafted membrane comprising a polyethylene film which is graft-copolymerized with a monomer having an ion exchange group, characterized in that said membrane has an area which is not grafted at all or an area of low degree grafting. By making use of this membrane, a small size and thin cell having excellent performance as well as satisfactory mechanical strength can be produced at low cost with great advantages.

Cell separator and cell

A method of producing a dimensionally stable battery separator characterized by grafting acrylic acid and/or methacrylic acid onto a polyethylene film, treating the resulting membrane with an aqueous alkaline solution, and drying the treated membrane under application of tension.

Method of producing a dimensionally stable battery separator

A battery separator composed of a composite sheet of film to which a monomer having a hydrophilic or electrolytic group is grafted is disclosed. Said film consists of a first polymeric layer containing a substance capable of catching a metal ion dissolved from a positive or negative active material and a second polymeric layer integrally bonded to either one or both sides of the first polymeric layer and which contains no such substance or contains it in a smaller amount that that contained in said first polymeric layer. Also disclosed is a method of producing a battery separator by irradiating such composite sheet of film with ionizing radiation and immersing the irradiated film in a solution of a monomer containing a hydrophilic or electrolytic group or bringing it into contact with the monomer solution to thereby graft the monomer to the film.

Battery separator and method of producing the same

The present invention relates to a high performance lead-acid storage battery having a special microporous separator between a positive and a negative plate in a cell of the battery. The separator is comprised of a microporous embossed thin sheet having many small projecting embossed parts which provides unique characteristics in a cell including low electric internal resistance in the cell, sufficient electrolyte between the plates in the cell and sufficient elasticity of the separator to prevent active material shedding, thereby giving a high performance at a high rate of discharge and long life.

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Takatsuki, Japan

Shiro Tanso