Patent ID: 7455750

Claim:
A process for making a meta- and para-aramid pulp for use as reinforcement material, comprising: (a) combining pulp ingredients including: (1) pieces of fibrous meta-aramid material, wherein the fibrous meta-aramid material is uncalendered paper having a thickness of 2 to 40 mils and a density of 0.1 to 0.4 g/cm 3 , being 10 to 90 wt % of the total solids in the ingredients, and having an average maximum dimension of no more than 50 mm; (2) para-aramid fiber being 10 to 90 wt % 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 wt % of the total ingredients; (b) mixing the ingredients to a substantially uniform slurry; (c) co-refining the slurry by simultaneously: (1) breaking apart the fibrous meta-aramid material pieces, and cutting and/or masticating the meta-aramid material, into fibril free, fibrous and non fibrous, meta-aramid particles; (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 to no more than 60 total wt % water, thereby producing a meta- and para-aramid pulp with the para-aramid fibrous structures contacting and wrapped partially around at least some of the meta-aramid particles.