Abstract: A multiply sheet product useful as a battery separator having at least two plies each in the form of a microporous sheet of predetermined length and breadth and a thickness of less than 10 mils wherein (a) at least one of said ply being a sheet capable of transforming to a substantially non-porous membrane at a temperature between about 80.degree. C. and 150.degree. C. while essentially maintaining its length and breadth dimensions and (b) at least one ply being a sheet capable of maintaining its dimensions and porosity at temperatures from ambient to at least about 10.degree. C. greater than the transformation temperature of sheet (a).

Abstract: A multiply sheet product useful as a battery separator having at least two plies each in the form of a microporous sheet of predetermined length and breadth and a thickness of less than 10 mils wherein (a) at least one of said ply being a sheet capable of transforming to a substantially non-porous membrane at a temperature between about 80.degree. and 150.degree. C. while essentially maintaining its length and breadth dimensions and (b) at least one ply being a sheet capable of maintaining its dimensions and porosity at temperatures from ambient to at least about 10.degree. C. greater than the transformation temperature of sheet (a).

Abstract: A battery separator is provided that has 30-70% polyolefin synthetic pulp, 15-65% siliceous filler and 1-35% by weight of long fibers having lengths of between 1/4 and 1 inch. The long fibers may be polyester fibers or glass fibers or a mixture. Cellulose may be included in an amount up to about 10%.A process for forming the battery separator is also revealed using standard paper making equipment but employing ionic copolymers containing acrylamide in cationic and anionic combination to give good affinity of the siliceous material and polyolefin. Alum and other processing aids are also included as are other procedural steps such as pressing the web.

Abstract: A battery separator is provided that has 30-70% polyolefin synthetic pulp, 15-65% siliceous filler and 1-35% by weight of long fibers having lengths of between 1/4 and 1 inch. The long fibers may be polyester fibers or glass fibers or a mixture. Cellulose may be included in an amount up to about 10%.A process for forming the battery separator is also revealed using standard paper making equipment but employing ionic copolymers containing acrylamide in cationic and anionic combination to give good affinity of the siliceous material and polyolefin. Alum and other processing aids are also included as are other procedural steps such as pressing the web.

Abstract: Battery separators with degradation resistant rib areas are produced from nonwoven mats of thermoplastic fibers by substantially fusing the fibers in raised regions of the mat. The fusion is progressively lessened toward the base of the rib. The rib is formed by the application of heat and pressure. The mat is also supplied with other important characteristics such as small pore size during treatment to compact its fibers.