Patent ID: 8728617

Claim:
A microporous material comprising a matrix of polyolefin, finely-divided, substantially water-insoluble particulate filler, a network of interconnecting pores communicating throughout the microporous material, and at least one retrospectively identifiable taggant material dispersed within the matrix, the at least one taggant material optionally being unique to an end user for the microporous material, wherein the polyolefin comprises 20 to 35 weight percent of the microporous material, the finely-divide, substantially water-insoluble particulate filler comprises 40 to 80 weight percent of the microporous material, and the taggant material is retrospectively identifiable by non-destructive means and comprises a visually distinguishable colored sequence and/or alphanumeric code, wherein the taggant material is present in the microporous material in an amount ranging from 0.001 to 3 weight percent based on the weight of the microporous material.