Process for preparing sheet composites containing crystalline phosphate fibers

A process for the preparation of sheet composites containing crystalline phosphate fibers which comprises:

• (a) bringing together in aqueous media, asbestiform calcium sodium phosphate fibers having an aspect ratio of from about 40:1 to about 100:1 and an average diameter of from about 1 .mu.m to about 10 .mu.m and a cationic resin, the cationic resin being present in an amount sufficient to provide a nominal positive ionic charge to the phosphate fibers, to form a cationic-resin treated phosphate fibers aqueous slurry;
• (b) mixing the cationic resin-treated phosphate fibers aqueous slurry from Step (a) with cellulosic fibers and carboxylated styrene-butadiene rubber rubber in proportions sufficient to provide a composition containing on a dry weight basis from about 70% to about 85% of the cationic-resin treated phosphate fibers, from about 3% to about 7% of the cellulosic fibers, and from about 10% to about 20% of the carboxylated styrene-butadiene rubber and form a fibrous material-rubber aqueous dispersion;
• (c) distributing and draining the fibrous material-rubber aqueous dispersion on a porous substrate to form a wet sheet-like solid phase or wet web;
• and
• (d) pressing and drying the wet web to yield the sheet composite containing, as a major fibers component the cationic resin-treated phosphate fibers and, as a minor fiber component, the auxiliary fibers.

A process for the preparation of sheet composite containing crystalline phosphate fibers which comprises:

• (a) bringing together in aqueous media asbestiform calcium M phosphates, wherein M is a metal cation selected from the group consisting of sodium and lihtium, and mixtures thereof, and a cationic resin, the cationic resin being present in an amount sufficient to provide a nominal positive ionic charge to the phosphate fibers, to form a cationic resin-treated phosphate fibers aqueous slurry;
• (b) mixing the cationic resin-treated phosphate fibers aqueous slurry from Step (a) with auxiliary fibers selected from the group consisting of cellulosic fibers, glass fibers rayon fibers, graphite fibers, polyamide fibers, polyester fibers, polyolefin fibers, and poly(vinyl chloride) fibers and a water insoluble organic polymeric binder in proportions sufficient to provide a composition containing on a dry basis from about 60% to about 95% of the cationic resin-treated phosphate fibers, from about 1% to about 15% of the auxiliary fibers, and from about 5% to about 30% of the water insoluble inorganic polymeric binder to form a fibrous material-polymeric binder aqueous dispersion;
• (c) distributing and draining the fibrous material-polymeric binder aqueous dispersion on a porous substrate to form a wet sheet-like solid phaes or wet web;
• and
• (d) pressing and drying the wet web to yield the sheet composites containing, as a major fiber component, the cationic resin-treated phosphates fibers and, as a minor fiber component, the auxiliary fibers.