Patent ID: 8652579

Claim:
A process for binding a fibrous material, the process comprising: applying to a surface of the fibrous material an aqueous binding composition to form a coated fibrous material, wherein the binding composition comprises: (a) a water-soluble polyamic acid formed by the reaction of: (i) a polycarboxylic acid or polyanhydride having a molecular weigh of at least 150 g/mol; and (ii) ammonia or an amine compound, and (b) an organic crosslinking agent capable of undergoing a covalent crosslinking reaction with the water-soluble polyamic acid when heated; and heating the coated fibrous material to crosslink the water-soluble polyamic acid with the organic crosslinking agent to form a cured binder, wherein one or more adjoining fibers of the fibrous material are bound to each other at cross over points by the cured binder.