Patent ID: 8431213
Filing Date: 2013-04-30
Classification: D21H,Y10T

Abstract:
1. A pressboard consisting of a plurality of plies having thermostable floc and at least 40 weight percent aramid fibrids, where the thermostable floc are fibers having a length of 2 to 25 millimeters and a diameter of 3 to 20 micrometers and losing not more than 10 percent of its tenacity after exposure to 250° C. for 10 minutes in air and where the fibrids are polymer products of particles having a length and width in order of 100 to 1000 micrometers and thickness in the order of 0.1 to 1 micrometer, the pressboard having a final average thickness of 0.9 mm or greater, the pressboard having an a void content of 25 volume percent or less, characterized in that the pressboard has a ply adhesion (Y) in megapascals defined by the equation wherein (X) is the thickness of the pressboard in millimeters, and wherein the ply adhesion is the peak load delamination of the structure in z-direction (out of plane) of the pressboard as measured in accordance with ASTM D 952-02, wherein the pressboard has compressibility of 1.6 percent or less and compression set of 0.18 percent or less.