Patent ID: 7803247

Claim:
A paper useful for electrical insulation, comprising: a) at least 20 weight percent floc containing a polymer or copolymer derived from an amine monomer selected from the group consisting of 4,4′diaminodiphenyl sulfone, 3,3′diaminodiphenyl sulfone, and mixtures thereof, the floc having a length of from 2 to 25 mm; and b) non-granular, fibrous or film-like polymer fibrids, the fibrids containing a polymer or copolymer derived from metaphenylene diamine, the fibrids having an average maximum dimension of 0.1 to 1 mm, a ratio of maximum to minimum dimension of 5:1 to 10:1, and a thickness of no more than 2 microns, wherein the papers have at least a 50% improvement in work-to-break values over papers made solely with poly(metaphenylene isophthalamide) floc.