An object of the present invention is to provide a porous hollow-fiber membrane satisfying both high strength and high pure-water permeation performance and at the same time, having high bending resistance. The present invention relates to a porous hollow-fiber membrane including a fluororesin-based polymer, in which the porous hollow-fiber membrane has a columnar texture oriented in a longitudinal direction of the porous hollow-fiber membrane and when a photograph of a cross-section parallel to the longitudinal direction of the porous hollow-fiber membrane is binarized into a structure portion and a void portion, the following 1) and 2) are satisfied: 1) a proportion of an area of the void portion is from 20 to 50%, and 2) a value obtained by dividing a total of peripheral lengths of the void portions by a total of areas of the void portions is 2.0 m.sup.1 or less.

The present invention provides a porous body having high strength, a small pore size, and excellent homogeneity. The porous body of the present invention includes polytetrafluoroethylene and has a microstructure that includes nodes and fibrils. The microstructure further includes, in addition to the nodes and the fibrils, fused points where a fibril that links two nodes and another fibril that links another two nodes are fused with each other.

A porous polytetrafluoroethylene (PTFE) membrane of the present disclosure has a water vapor permeability, as measured according to Japanese Industrial Standard (JIS) L 1099 (method B-1), of 150000 g/(m.sup.2.Math.day) or more in a thickness direction of the membrane. The porous PTFE membrane of the present disclosure, when attached as a waterproof air-permeable membrane to a housing of an electrical component or electrical device, allows water vapor residing inside the housing to be quickly discharged out of the housing.

A porous polytetrafluoroethylene (PTFE) membrane of the present disclosure is a membrane having an average fibril length of 50 m or more, having an average node length 5 or more times larger than the average fibril length, and having an average node area ratio of 5% or less. The porous PTFE membrane of the present disclosure, when attached as a waterproof air-permeable membrane to a housing of an electrical component or electrical device, allows water vapor residing inside the housing to be quickly discharged out of the housing.

A Polyvinylidene fluoride-based microporous membrane comprising: a substrate film; and the following microporous membrane, wherein the microporous membrane is an asymmetric membrane, and has a skin layer in which micropores are formed and a support layer which supports the skin layer and in which pores larger than the micropores are formed, a material of the microporous membrane is a polyvinylidene fluoride-based resin, the skin layer has a plurality of spherical bodies, a plurality of linear binding materials extend three-dimensionally from the respective spherical bodies, the adjacent spherical bodies are connected with each other by the linear binding materials to form a three-dimensional network structure where the spherical bodies serve as intersections, and the number of defects (the number of colored coarse voids) is less than 20.

In at least one embodiment, a separator is provided with a fibrous mat for retaining the active material on an electrode of a lead-acid battery. New or improved mats, separators, batteries, methods, and/or systems are also disclosed, shown, claimed, and/or provided. For example, in at least one possibly preferred embodiment, a composite separator is provided with a fibrous mat for retaining the active material on an electrode of a lead-acid battery. In at least one possibly particularly preferred embodiment, a PE membrane separator is provided with at least one fibrous mat for retaining the active material on an electrode of a lead-acid battery. In accordance with at least certain embodiments, aspects and/or objects, the present invention, application, or disclosure may provide solutions, new products, improved products, new methods, and/or improved methods, and/or may address issues, needs, and/or problems of PAM shedding. NAM shedding, electrode distortion, active material shedding, active material loss, and/or physical separation, electrode effectiveness, battery performance, battery life, and/or cycle life, and/or may provide new battery separators, new battery technology, and/or new battery methods and/or systems that address the challenges arising from current lead acid batteries or battery systems, especially new battery separators, new battery technology, and/or new battery methods and/or systems adapted to prevent or impede the shedding of active material from the electrodes, preferably or particularly in enhanced flooded lead acid batteries, PSoC batteries, ISS batteries, ESS batteries, and/or the like.

An air filter medium includes a fluororesin porous membrane and a supporting member stacked on top of each other. The air filter medium has a permeability ratio (permeability after disinfection treatment/permeability before disinfection treatment) of 5.0 or less, the permeability ratio being a ratio of permeabilities of the air filter media before and after the disinfection treatment of the fluororesin porous membrane as determined using NaCl particles having a particle size of 0.1 ?m, and a pressure loss ratio (pressure loss after disinfection treatment/pressure loss before disinfection treatment) of 0.83 or more and 1.15 or less, the pressure loss ratio being a ratio of pressure losses of the air filter media before and after the disinfection treatment of the fluororesin porous membrane.

A novel or improved base film for impregnation, impregnated base film, product incorporating the impregnated base film, and/or related methods as shown, claimed or described herein.

A polymer including a sub-unit comprising a Troger's base moiety represented by: Formula (I) wherein L comprises an arylene group including at least one substituent group selected from: i) a crosslinking bond and ii) a functional group selected from at least one of: hydroxyl, phosphonic acid, carboxylic acid and sulfonic acid and their corresponding salt or ester; alkynyl, alkynyl ether, cyanate, epoxide, glycidyl ether or ester. ##STR00001##

An ion permeable membrane includes ion conductor particles and a fiber base material, in which each of the ion conductor particles has a first portion embedded inside the fiber base material, and a second portion exposed on outside surfaces of the fiber base material, and the second portions are continuous between an upper surface and a lower surface in a thickness direction of the ion permeable membrane.