W. R. Grace Co.

W. R. Grace Co.-conn.

Howard J Troffkin

Christian B Lundsager

Joseph T Lundquist

Robert M Spotnitz

Nigel I Palmer

Richard T Giovannoni

Burton M Rein

Yihong Guo

James M Gaidis

Arnold M Rosenberg

The present invention is directed to a multi-ply unfilled microporous sheet product composed of at least one first ply and at least one second ply which are, respectively, formed from polymeric compositions having different rheological properties and to a method of forming said sheet product.

Battery separator

A process of having a microporous multiply sheet product which is capable of becoming non-porous at a predetermined elevated transformation temperature is formed by first forming a non-porous, multiply initial sheet product having at least one first ply and at least one second ply, each with its own viscosity profile. The initial sheet product is then stretched and annealed to impart porosity to the sheet product.

Process of making a battery separator

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).

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).

Reinforced concrete structures often suffer corrosion damage. This damage is repaired by removing the layer of distressed concrete around the metal reinforcement and filling in the removed area with a high content calcium nitrite-containing cement based composition.

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Potomac, MD, United States of America

Howard J Troffkin