Methods of improving lofting agent retention using bicomponent fibers

A method of producing a porous composite article comprising:

• combining inorganic reinforcing fibers, organic reinforcing fibers, a lofting agent comprising expandable microspheres, and a thermoplastic material in a liquid to produce an aqueous foam, wherein the organic reinforcing fibers comprise a core-shell arrangement, wherein a shell material in the shell of the core-shell arrangement comprises a melting point that differs by one to ten degrees from, or is the same as, a melting point of the thermoplastic material, wherein the shell of the organic reinforcing fibers comprises a linear low density polyethylene having a density between about 0.91 g/cm3 to about 0.94 g/cm3, and wherein a core material in the core of the core-shell arrangement comprises a melting point that is at least twenty degrees Celsius higher than the melting point of the thermoplastic material, wherein the core of the organic reinforcing fibers comprises a polyester or a polyamide;
• depositing the aqueous foam onto a moving wire screen;
• removing liquid from the deposited aqueous foam on the moving wire screen to form a web of open cell structures formed from the thermoplastic material, the inorganic fibers, the organic reinforcing fibers, and the lofting agent, wherein lofting agent retention is at least 50% by volume in the presence of the inorganic and organic reinforcing fibers, and thermoplastic material;
• and
• compressing the formed web comprising the lofting agent to provide a porous composite article.