Curable aqueous composition

#This patent application claims the benefit of the earlier filed Chinese Patent Application No. 200910261573.9 filed on Dec. 18, 2009 under 37 CFR 1.55(a).

#This invention relates to a curable aqueous composition, a method for forming a treated flexible substrate using the curable aqueous composition, and the substrate so treated.

#Flexible substrates such as paper, woven fabrics and non-woven fabrics are frequently consolidated or strengthened by treating with a polymeric binder to dispose in or on the substrate. The tensile strength of treated substrate in the status of dry, water immersed (wet) and isopropyl alcohol immersed (IPA) is one of the most important properties to reflect the quality of binder. When a binder treated substrate has high dry, wet and IPA tensile strength, it usually has improved properties including resiliency, crack resistance, dryclean resistance, wash durability, tear strength and fold endurance.

#For the purpose of describing the components in the compositions of this invention, all phrases comprising parenthesis denote either or both of the included parenthetical matter and its absence. For example, the phrase “(co)polymer” includes, in the alternative, polymer, copolymer and mixtures thereof; and the phrase “(meth)acrylate” means acrylate, methacrylate, and/or mixtures thereof.

#The curable aqueous composition of the present invention comprises a (co)polymer or a cold blend of (co)polymer. The phrase “curable” herein is meant capable of a structural or morphological change which is sufficient to alter the properties of a flexible substrate to which an effective amount of polymeric binder has been applied such as, for example, covalent chemical reaction, ionic interaction or clustering, improved adhesion to the substrate, phase transformation or inversion, hydrogen bonding, and the like. The (co)polymer herein is a (co)polymer prepared by the addition polymerization of ethylenically-unsaturated monomers in an aqueous emulsion or solution polymerization process; the cold blend of (co)polymer herein is the mixture of two or more emulsion or solution (co)polymer. By “aqueous composition” herein is meant a composition in which the continuous phase is water or a mixture including predominantly water but also including water-miscible solvent. A “curable composition” herein is one that undergoes a chemical process to some extent such as covalent bond formation under the agency of added energy, most typically heating.

#The (co)polymer comprises, as (co)polymerized units, from 0.05 to 10% by weight, preferably from 2 to 6% by weight, based on the dry weight of the aqueous composition, ethylenically unsaturated acidic monomer having at least two carboxylic acid groups such as, for example, itaconic acid, fumaric acid, maleic acid, including their salts, and mixtures thereof. Preferred is itaconic acid.