Non-woven fibrous composite materials and method for the preparation thereof

Claim 1

A process for the preparation of non-woven, fibrous composite materials, which process comprises the steps of: a. separately mixing together with at least a sufficient quantity of water to form a first aqueous dispersion, i. a cellulose fiber component comprising at least about 15 percent of the composite materials and further comprising predominately softwood pulp fibers, which fibers in the form of a TAPPI Standard Handsheet have a breaking length of at least eight kilometers (8 km) and a density of at least sixty-seven one-hundredths of a gram per cubic centimeter (0.67 g/cc), and ii. a filler component comprising at least about 20 percent of the composite materials and further comprising at least one particulate anionic, water-insoluble inorganic filler; b. mixing together with a least a sufficient quantity of water to form a second aqueous dispersion, a latex blend component comprising at least about 20 percent of the composite materials and further comprising i. a soft resin component comprising an anionic, water-insoluble soft acrylic binder resin, which resin has a glass transition temperature of from -30° C. to -10° C., and ii. a hard resin component comprising an anionic, water-insoluble hard acrylic binder resin, which resin has a glass transition temperature of from 20° C. to 40° C.; c. mixing together with at least a sufficient quantity of water to form a third aqueous dispersion, i. a non-cellulosic fiber component comprising at least one water-dispersible fiber chosen from the group consisting of glass fibers, rock wool and other mineral fibers; d. preparing a first combined aqueous dispersion by combining the first aqueous dispersion prepared in step (a) with the second aqueous dispersion prepared in step (b); e. adding to the first combined aqueous dispersion prepared in step (d), an amount in excess of that required to effectively destabilize the first combined aqueous dispersion and cause coagulation and absorption of the latices and filler by the cellulosis fibers, a first flocculant component comprising at least one water-soluble cationic organic wet-strength resin flocculant; f. preparing a second combined aqueous dispersion by combining the first combined aqueous dispersion prepared in step (d) with the third aqueous dispersion prepared in step (c); g. adding to the second combined aqueous dispersion prepared in step (f) a second flocculant component comprising an anionic organic flocculant in a sufficient quantity to adjust the electrokinetic potential of said second combined aqueous dispersion to from about -10 millivolts to about +10 millivolts; h. precipitating substantially all of said resin components and filler component into a bonded relationship with said cellulosic and non-cellulosic fibrous components i. forming said precipitated components of step h. into a sheet.