| 摘要 |
The present invention is directed to a sheet product useful as a battery separator. The sheet product is composed of a microporous polymeric sheet product having at least one ply, wherein at least one ply comprises a microporous sheet formed from a polymeric composition of a first polymer having low glass transition temperature and having a second ply coating a major portion of the pore and external surfaces of the first polymer microporous sheet. The first polymer is selected from a thermoplastic polymer that has a glass transition temperature of less than -50° C. and a melt temperature of at least 70° C. The second polymer coating a major portion of the microporous sheet of first polymer is selected from (a) a thermoplastic polymer having a glass transition temperature which is at least 60° C. above that of the first polymer or (b) a thermoset polymer having a degradation temperature that is at least 40° C. higher than the melt temperature of the first polymer The present battery separator exhibits a high degree of dimensional stability while causing shut-down of the battery's electrochemical reaction under elevated temperature conditions. |
