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US 8,709,641 B2Granted
Microporous membranes and methods for producing and using such membranes
AssigneeToray Battery Separator Film Co., Ltd.
InventorsTakeshi Ishihara, Satoshi Miyaoka, Koichi Kono, Donna J. Crowther, Patrick Brant, Kazuhiro Yamada
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Abstract
A microporous membrane comprising layers, wherein at least one layer comprises a first polymer having a Tm in the range of 115.0° C. to 130.0° C. and an Mw of from 5.0×103 to 4.0×105, and the membrane has a shutdown temperature≦130.5° C. and a rupture temperature≧170.0° C.
Claims18
A microporous membrane comprising layers, wherein:
- 1) at least one layer comprises a first polymer comprising an ethylene/α-olefin copolymer having a Tm of 121.0 to 125.0° C. and an Mw of 5.0×103 to 4.0×105,
- 2) at least a second layer of the membrane comprises 15 wt. % to 40 wt. % of polypropylene having an Mw≧5.0×105 and a Tm≧150° C., 0 wt. % to 10 wt. % of polyethylene having an Mw>1.0×106, and 50 wt. % to 85 wt. % of polyethylene having an Mw≦1.0×106, the weight percents being based on the weight of the second layer,
- 3) a third layer comprises the ethylene/α-olefin copolymer,
- 4) the second layer is located between the first and third layers,
- 5) the first and third layers each individually comprise from 3 wt. % to 50 wt. %, based on the weight of the respective first layer or third layer, and
- 6) the membrane has a shutdown temperature ≦130.5° C., a rupture temperature ≧170.0° C. and a normalized air permeability ≦700 seconds/100 cm3/20 μm.
3 more elements
A multilayer microporous membrane,
- first and third layers individually comprising 20.0 wt. % to 30.0 wt. % of an ethylene/α-olefin copolymer having an Mw from 1.0×104 to 7.0×104, 45.0 wt. % to 70.0 wt. % of an polyethylene having an Mw≦1.0×106, and 0.0 wt. % to 35.0 wt. % of a polyethylene having an Mw>1.0×106;
- based on the weight of the first and third layers, respectively, and
- a second layer located between the first and third layers, comprising 20.0% to 80.0 wt. % of a polypropylene having an Mw of 1.1×106 and a heat of fusion >110.0 J/g, 0 wt. % to 10.0 wt. % of a polyethylene having an Mw>1.0×106 and 20.0 wt. % to 70.0 wt. % of a polyethylene having an Mw>1.0×106, the weight percents being based on the weight of the second layer;
- the membrane having a shutdown temperature ≦130.5° C. and a rupture temperature ≧170.0° C.
1 more element
A method of producing a microporous membrane comprising:
- a. combining at least a first polymer and at least one first diluent, the first polymer comprising an ethylene/α-olefin copolymer having a Tm of 121.0° C. to 125.0° C. and an Mw of 5.0×103 to 4.0×105;
- b. combining at least a second polymer and at least a second diluent, the second polymer comprising a polypropylene having an Mw≧5.0×105 and a Tm≧150° C., a polyethylene having an Mw>1.0×106 and a polyethylene having an Mw≦1.0×106, wherein the amount of polypropylene is 15 wt. % to 40 wt. %, the amount of polyethylene having an Mw>1.0×106 is 0 wt. % to 10 wt. % and the amount of polyethylene having an Mw 50 wt. % to 85 wt. %, the weight percents being based on the total polymer weight of the composition;
- c. combining at least a third polymer comprising an ethylene/α-olefin copolymer having a Tm of 121.0° C. to 125.0° C. and an Mw of 5.0×103 to 4.0×105 with at least one third diluent;
- d. forming a multilayer extrudate from the combined first polymer, the polypropylene second polymer and the diluents, the extrudate having a first layer containing the first polymer, a second layer containing the second polymer, and a second layer located between the first and third layers containing the first polymer;
- and
- e. removing at least a portion of the first, second, and third diluents from the stretched multilayer extrudate to produce the membrane.
3 more elements
Dependencies are inferred from the claim text.