Toyo Boseki Kabushiki Kaisha

Hiroki Yamaguchi

Masahiro Yamashita

Toshio Tanaka

Naohiko Takimoto

Yoshimitsu Sakaguchi

Shiro Hamamoto

Kousuke Sasai

Kota Kitamura

Kouta Kitamura

The present invention relates to a sulfonic acid group-containing polymer excellent in ion conductivity and durability, a method for producing the same, a resin composition containing the sulfonic acid group-containing polymer, a polymer electrolyte membrane, a polymer electrolyte membrane/electrode assembly, and a fuel cell. The sulfonic acid group-containing polymer of the present invention, in a first embodiment, includes a constituent represented by the following chemical formula 1: wherein X represents hydrogen or a monovalent cation species; Y represents a sulfone group or a ketone group; and n represents an arbitrary integer not less than 2.

Sulfonic acid group-containing polymer, method for producing the same, resin composition containing such sulfonic acid group-containing polymer, polymer electrolyte membrane, polymer electrolyte membrane/electrode assembly, and fuel cell

The invention provides a method for producing a polymer electrolyte membrane including (A) a membrane formation step of forming a membrane-form product of an ionic group-containing polymer electrolyte on a support, (B) an acid treatment step of exchanging the ionic group into an acid type by bringing the membrane into contact with an inorganic acid-containing acidic liquid, (C) an acid removal step of removing a free acid in the acid-treated membrane, and (D) a drying step of drying the acid-removed membrane, wherein the steps (B) to (D) are carried out without separating the membrane from the support.

Method for producing a polymer electrolyte membrane

An object of the present invention is to provide a thin battery separator having an excellent nitrate group trapping performance and a high piercing strength. The inventive separator for a secondary battery, which can accomplish such an object, is made of a resin composition mainly containing a polyolefin having a hydrophilic functional group, wherein the resin composition has a content (ratio to a total resin amount) of a low-density polyethylene of 20 mass % or less, a piercing strength of 5 to 100 N, a Metsuke of 20 to 75 g/m, a thickness of 15 to 150 &#x3bc;m, and an unneutralized hydrophilic functional group amount of 1&#xd7;10to 5&#xd7;10mol/m.

Separator for secondary battery and method for producing the same

A battery including a separator having a satisfactory ammonia trapping property is speculated to exhibit a less self-discharge and a higher capacity-holding rate. The ammonia trapping property is speculated to be increased with an increasing degree of sulfonation of a constitutive polyolefin fiber. However, a highly sulfonated conventional polyolefin has a deteriorated fiber strength and highly sulfonated portions thereof are peeled or eliminated, and the resulting fiber cannot have a significantly high degree of sulfonation. The invention is therefore intended to provide a separator having an improved ammonia trapping property. The invented separator includes a polyolefin resin fiber having large amounts of introduced sulfonic groups. Specifically, the separator is one containing a fiber obtained by sulfonating a polyolefin resin fiber having an intrinsic viscosity number of 0.2 to 1.0 dl/g, one including a fiber obtained by sulfonating a polyolefin resin fiber and having a BET specific surface area of 0.5 m /g or more, or one including a fiber obtained by oxidizing a polyolefin fiber and sulfonating the oxidized fiber.

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Ohtsu, Japan

Hiroki Yamaguchi