Battery separator
OwnerGijsbertus H.M. Calisinventor
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Abstract
A microporous film of polyethylene having an intrinsic viscosity above 5 dl/g is prepared from a homogeneous solution in an evaporable solvent. The film is cooled and evaporable solvent is evaporated at a temperature below the dissolution temperature. The film is stretched to produce the micorporous film and is passed through a calender. The microporous films with a porosity of up to about 70% by volume and a battery separator quality factor (F) of at least 2.5 are described. Battery separators formed from the microporous films are also described.
Claims4
Microporous film comprising polyethylene having an intrinsic viscosity of more than 5 dl/g and a porosity of at most 70 vol. %, said film having a battery separator quality factor (F) of at least 2.5 and
- F=BW.PR/(G.t),
- where BW is the basic weight (g/m2),
- PR the puncture resistance in g,
- G the Gurley in sec/50 ml and
- t the film's thickness in μm.
Dependencies are inferred from the claim text.