Battery separator, process for producing the same, and alkaline battery

摘要

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<2>/g or more, or one including a fiber obtained by oxidizing a polyolefin fiber and sulfonating the oxidized fiber.