Patent ID: 11862814
Assignee: DARAMIC, LLC
Field: Chemical engineering (Chemistry)
Classification: CPC H  B  C  Y | IPC B  C  H

Claim 0:
1. A battery separator microporous material made by a process comprising:
mixing ultra-high molecular weight polyethylene (UHMWPE), siliceous filler and processing plasticizer together to form a mixture, having a weight ratio of siliceous filler to UHMWPE of from 1:9 to 15:1 by weight and having the ratio of siliceous filler to processing plasticizer be 1:15 to 3:1 by weight;
extruding said mixture to form a sheet;
calendering said sheet;
extracting all or part of said processing plasticizer from said sheet to produce a matrix comprising UHMWPE and said particulate siliceous filler, the siliceous filler being distributed throughout said matrix, to produce a microporous matrix sheet;
stretching said microporous matrix sheet in at least one stretching direction to a stretch ratio of at least 1.5 to produce a stretched microporous matrix sheet; and
calendering said stretched microporous matrix sheet under conditions to form the battery separator microporous material having pores having a diameter from 0.01 micrometers to 0.1 micrometer, and wherein the siliceous filler constitutes from 5 percent to 95 percent by weight of the battery separator microporous material,
wherein the battery separator microporous material has an MD tensile strength from 40 to 65 N/mm2, and a TD tensile strength from 28 to 55 N/mm2.