Patent ID: 7740741

Claim:
A process for making a para-aramid pulp including meta-aramid fibrids for use as reinforcement material, comprising: (a) combining pulp ingredients including: (1) never-dried meta-aramid fibrids having an average maximum dimension of 0.2 to 1 mm, a ratio of maximum to minimum dimension of 5:1 to 10:1, and a thickness of no more than 2 micrometers, and being a 10 to 90 weight percent of the total solids in the ingredients; (2) para-aramid fiber being 10 to 90 weight percent of the total solids in the ingredients, and having an average length of no more than 10 cm; and (3) water being 95 to 99 weight percent of the total ingredients; (b) mixing the ingredients to a substantially uniform slurry, wherein random samples of the slurry contain the same wt % of the concentration of each of the starting ingredients as in the total ingredients in the combination step plus or minus 10 wt % (c) co-refining the slurry by simultaneously: (1) shearing and/or masticating the meta-aramid fibrids into fibril-free refined meta-aramid fibrids having an average maximum dimension of 0.1 to 0.5 mm; (2) fibrillating, cutting and masticating the para-aramid fiber to irregularly shaped fibrillated fibrous structures; and (3) dispersing all solids such that the refined slurry is substantially uniform; and (d) removing water from the refined slurry, thereby producing a meta- and para-aramid pulp with the para-aramid fibrous structures contacting and wrapped partially around at least some of the refined meta-aramid fibrids.