Microporous material and a method of making same

Patent metadata

Field	Value
Publication number	US-2017072610-A1
Application number	US-201615345184-A
Country	US
Kind code	A1
Filing date	Nov 7, 2016
Priority date	Dec 7, 2004
Publication date	Mar 16, 2017
Grant date	—

Abstract

A method for producing a microporous material comprising the steps of: providing an ultrahigh molecular weight polyethylene (UHMWPE); providing a filler; providing a processing plasticizer; adding the filler to the UHMWPE in a mixture being in the range of from about 1:9 to about 15:1 filler to UHMWPE by weight; adding the processing plasticizer to the mixture; extruding the mixture to form a sheet from the mixture; calendering the sheet; extracting the processing plasticizer from the sheet to produce a matrix comprising UHMWPE and the filler distributed throughout the matrix; stretching the microporous material in at least one direction to a stretch ratio of at least about 1.5 to produce a stretched microporous matrix; and subsequently calendering the stretched microporous matrix to produce a microporous material which exhibits improved physical and dimensional stability properties over the stretched microporous matrix.

First claim

What is claimed is:

1 . A method for producing a microporous material comprising the steps of:
mixing ultra high molecular weight polyethylene (UHMWPE), filler and processing plasticizer together to form a mixture, having a weight ratio of filler to UHMWPE of from 1:9 to 15:1 by weight; wherein the filler constitutes from about 5 percent to about 95 percent by weight of the microporous material; 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 filler, the 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 about 1.5 to produce a stretched microporous matrix sheet; and calendering said stretched microporous matrix sheet.

2 . The method of claim 1 , wherein the filler constitutes from about 45 percent to about 95 percent by weight of the microporous material.

3 . The method of claim 1 , wherein the filler constitutes from about 55 percent to about 80 percent by weight of the microporous material.

4 . The method of claim 1 , wherein the filler constitutes from about 61.1 percent by weight of the microporous material.

5 . The method of claim 1 , wherein the filler is selected from silica, precipitated silica, silica gel, or fumed silica.

6 . The method of claim 1 , wherein the filler is silica.

7 . The method of claim 1 , wherein the ratio of filler to processing plasticizer is 1:15 to 3:1 by weight.

8 . The method of claim 1 , wherein the ratio of filler to UHMWPE is about 2.6.

9 . The method of claim 1 where said microporous matrix sheet is stretched in at least one direction to a stretch ratio from about 1.5 to 15.

10 . The method of claim 1 where said UHMWPE is mixed with a high density (HD) polyethylene to produce a polyolefin mixture, where said polyolefin mixture has at least 50% UHMWPE by weight of said polyolefin mixture; where said filler to said polyolefin mixture is in a range of from 1:9 to 15:1 filler to polyolefin mixture by weight and where said matrix comprises UHMWPE and HD polyethylene and said particulate filler distributed throughout said matrix.

11 . A method for producing a microporous material comprising the steps of:
mixing ultra high molecular weight polyethylene (UHMWPE), filler and processing plasticizer together to form a mixture, having a weight ratio of filler to UHMWPE of from 1:9 to 15:1 by weight; wherein the filler constitutes from about 5 percent to about 95 percent by weight of the microporous material; 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 filler, the 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 about 1.5 to produce a stretched microporous matrix sheet; and calendering said stretched microporous matrix sheet; wherein said microporous matrix sheet having a thickness of no greater than 53.3 microns and a tensile strength in the machine direction of at least 72.9 N/mm 2 .

12 . The method of claim 11 , wherein the filler constitutes from about 45 percent to about 95 percent by weight of the microporous material.

13 . The method of claim 11 , wherein the filler constitutes from about 55 percent to about 80 percent by weight of the microporous material.

14 . The method of claim 11 , wherein the filler constitutes from about 61.1 percent by weight of the microporous material.

15 . The method of claim 11 , wherein the filler is selected from silica, precipitated silica, silica gel, or fumed silica.

16 . The method of claim 11 , wherein the filler is silica.

17 . The method of claim 11 , wherein the ratio of filler to processing plasticizer is 1:15 to 3:1 by weight.

18 . The method of claim 11 , wherein the ratio of filler to UHMWPE is about 2.6.

19 . The method of claim 11 where said microporous matrix sheet is stretched in at least one direction to a stretch ratio from about 1.5 to 15.

20 . The method of claim 11 where said UHMWPE is mixed with a high density (HD) polyethylene to produce a polyolefin mixture, where said polyolefin mixture has at least 50% UHMWPE by weight of said polyolefin mixture; where said filler to said polyolefin mixture is in a range of from 1:9 to 15:1 filler to polyolefin mixture by weight and where said matrix comprises UHMWPE and HD polyethylene and said particulate filler distributed throughout said matrix.

21 . The method of claim 1 , wherein the filler includes carbon material.

22 . The method of claim 21 , wherein the carbon material is at least one of carbon black, activated carbons, and carbon fibers.

23 . The method of claim 11 , wherein the filler includes carbon material.

24 . The method of claim 23 , wherein the carbon material is at least one of carbon black, activated carbons, and carbon fibers.

25 . A microporous material produced by the method of claim 1 .

26 . A battery separator comprising the microporous material of claim 25 .

27 . A microporous material produced by the method of claim 11 .

28 . A battery separator comprising the microporous material of claim 27 .

29 . A microporous material produced by the method of claim 21 .

30 . A battery separator comprising the microporous material of claim 29 .

31 . A microporous material produced by the method of claim 23 .

32 . A battery separator comprising the microporous material of claim 31 .

Assignees

• Daramic Llc

Inventors

• Miller Eric H
• Yaritz Joseph G
• Demeuse Mark T
• Whear J Kevin

Classifications

• H01M50/494

  Tensile strength · CPC title

• H01M50/434

  Ceramics · CPC title

• H01M50/491

  Porosity · CPC title

• H01M50/489

  Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties · CPC title

• C08J2323/06

  Polyethene · CPC title