Microporous material and a method of making same

Patent metadata

Field	Value
Publication number	US-2017207434-A1
Application number	US-201715416477-A
Country	US
Kind code	A1
Filing date	Jan 26, 2017
Priority date	Dec 7, 2004
Publication date	Jul 20, 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

1 - 37 . (canceled)

38 . A microporous membrane comprising:
a mixture of ultrahigh molecular weight polyethylene (UHMWPE) and filler in a weight ratio of filler to UHMWPE in a range of 1:9 to 15:1, the membrane having a plurality of micropores, a porosity in the range of 30-80%, and a machine direction (MD) tensile strength of greater than 25 N/mm 2 when said membrane has a thickness in a range of 17.8 to 71.1 micrometers, said membrane being a stretched and subsequently calendered membrane and having a pore size distribution where an average pore diameter is in a range of 0.01 to 0.60 micrometers and no pore with a pore size greater than 1 micron, wherein the membrane is at least one layer of a battery separator.

39 . The microporous membrane of claim 38 , having a wet out time of less than 180 seconds.

40 . The microporous membrane of claim 38 , having a shrinkage in the machine direction of less than 10%.

41 . The microporous membrane of claim 38 , where said filler is selected from the group consisting of: silica, mica, montmorillonite, kaolinite, asbestos, talc, diatomaceous earth, vermiculite, natural and synthetic zeolites, cement, calcium silicate, clay, aluminum silicate, sodium aluminum silicate, aluminum polysilicate, alumina silica gels, glass particles, carbon black, activated carbon, carbon fibers, charcoal, graphite, titanium oxide, lead oxide, tungsten, iron oxide, copper oxide, zinc oxide, antimony oxide, zirconia, magnesia, alumina, molybdenum disulfide, zinc sulfide, barium sulfate, strontium sulfate, calcium carbonate, and magnesium carbonate.

42 . The microporous membrane of claim 38 , where said filler is selected from the group consisting of: silica, precipitated silica, silica gel, fumed silica, mica, talc, diatomaceous earth, carbon black, activated carbons, carbon fibers, titanium oxide and calcium carbonate.

43 . The microporous membrane of claim 38 , 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 a weight ratio of said filler to said polyolefin mixture is in a range of from 1:9 to 15:1; and where said mixture comprises UHMWPE and HD polyethylene and said filler is distributed throughout said mixture.

44 . The microporous membrane of claim 38 , where said microporous membrane has no pores greater in size than 0.50 micrometers; and
where a median pore size being between or equal to 0.01 and 0.3 micrometers and said pores vary in size by plus or minus 0.2 micrometers or less.

45 . A microporous membrane comprising:
a mixture of ultrahigh molecular weight polyethylene (UHMWPE) and filler in a weight ratio of filler to UHMWPE in a range of 1:9 to 15:1, the membrane having a plurality of micropores, a porosity in the range of 30-80%, and a machine direction (MD) tensile strength of greater than 25 N/mm 2 when said membrane has a thickness of less than 75 micrometers, said membrane being a stretched and subsequently calendered membrane and having a pore size distribution where an average pore diameter is in a range of 0.01 to 0.60 micrometers and no pore with a pore size greater than 1 micron, wherein the membrane is at least one layer of a battery separator.

46 . The microporous membrane of claim 45 , having a wet out time of less than 180 seconds.

47 . The microporous membrane of claim 45 , having a shrinkage in the machine direction of less than 10%.

48 . The microporous membrane of claim 45 , where said filler is selected from the group consisting of: silica, precipitated silica, silica gel, fumed silica, mica, talc, diatomaceous earth, carbon black, activated carbons, carbon fibers, titanium oxide and calcium carbonate.

49 . The microporous membrane of claim 45 , 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 a weight ratio of said filler to said polyolefin mixture is in a range of from 1:9 to 15:1 and where said mixture comprises UHMWPE and HD polyethylene and said filler is distributed throughout said mixture.

50 . A microporous membrane comprising:
a mixture of ultrahigh molecular weight polyethylene (UHMWPE) and a particulate silica filler distributed throughout said microporous membrane; said filler constitutes from about 5 percent to 95 percent by weight of said microporous membrane; said microporous membrane has a network of interconnecting pores communicating throughout said microporous membrane, said pores constituting at least 45 percent by volume of said microporous membrane, and said pores have a diameter no greater than 0.6 microns, and a machine direction (MD) tensile strength of greater than 25 N/mm 2 when said membrane has a thickness of less than 75 micrometers, wherein the membrane is at least one layer of a battery separator.

51 . The microporous membrane of claim 50 , having a wet out time of less than 180 seconds.

52 . The microporous membrane of claim 50 , having a shrinkage in the machine direction of less than 10%.

53 . The microporous membrane of claim 50 , 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 a weight ratio of said filler to said polyolefin mixture is in a range of from 1:9 to 15:1 and where said mixture comprises UHMWPE and HD polyethylene and said filler is distributed throughout said mixture.

54 . The microporous membrane of claim 50 , where said microporous membrane has no pores greater in size than 0.50 micrometers; and
where a median pore size being between or equal to 0.01 and 0.3 micrometers and said pores vary in size by plus or minus 0.2 micrometers or less.

55 . A battery separator comprising the microporous membrane of claim 38 .

56 . A battery comprising the battery separator of claim 55 .

57 . A battery separator comprising the microporous membrane of claim 45 .

58 . A battery comprising the battery separator of claim 57 .

59 . A battery separator comprising the microporous membrane of claim 50 .

60 . A battery comprising the battery separator of claim 59 .

61 . The battery of claim 56 , wherein the battery is selected from the group of lead acid batteries, Edison batteries, nickel-cadmium batteries, zinc batteries, nickel metal hydride batteries, silver oxide batteries, Leclanche batteries, magnesium batteries, alkaline batteries, mercury batteries, mercad batteries, lithium primary and lithium secondary batteries, nickel hydrogen batteries, sodium sulfur batteries, and sodium nickel chloride batteries.

62 . The battery of claim 58 , wherein the battery is selected from the group of lead acid batteries, Edison batteries, nickel-cadmium batteries, zinc batteries, nickel metal hydride batteries, silver oxide batteries, Leclanche batteries, magnesium batteries, alkaline batteries, mercury batteries, mercad batteries, lithium primary and lithium secondary batteries, nickel hydrogen batteries, sodium sulfur batteries, and sodium nickel chloride batteries.

63 . The battery of claim 60 , wherein the battery is selected from the group of lead acid batteries, Edison batteries, nickel-cadmium batteries, zinc batteries, nickel metal hydri

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

• H01M10/06

  Lead-acid accumulators (semi-lead accumulators H01M10/20) · CPC title