Appeal No. 2003-0029
Application No. 09/385,933
Best discloses that the puncture propagation tear in both the machine and transverse
directions is important for determination of real world performance of the film.
The invention of Best differs from the claimed invention in that the film is not
microporous.
Yu ‘281 discloses the formation of microporous films from polymers
comprising a majority of a polypropylene, polyethylene, or a copolymer thereof. The
microporous films are useful in the formation of battery separators. (Col. 3). Yu ‘281
discloses that puncture strength is a concern in the formation of battery separators.
(Col. 2, ll. 11 to 15). Yu ‘281 discloses that the microporous films are formed by
blown film extrusion process, annealing the film and stretching the resultant annealed
film to form the microporous film. (Col. 2, ll. 43 to 55). In the exemplified
embodiment of Yu ‘281, the precursor to the microporous film is extruded at a blow
up ratio of 1.
Yu ‘911 discloses the formation of microporous films from polymers
comprising a majority of a polypropylene, polyethylene, or a copolymer thereof. The
microporous films are useful in the formation of battery separators. (Cols. 3-4). Yu
‘911 discloses that puncture strength is a concern in the formation of battery
separators. (Col. 1, ll. 27 to 36). Yu ‘911 discloses that the microporous films are
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