Patent ID: 7772138

Claim:
A nonwoven fabric comprising fibrous material and a binder material, wherein the binder material comprises an ion-sensitive polymer comprising the polymerization product of about 5 to about 10 mol percent of 2-acrylamido-2-methyl-1-propanesulfonic acid, one or more about 83 to about 93 mole percent alkyl acrylates and about 2 to about 7 mole percent of an anhydride/dicarboxylate selected from itaconic anhydride, crotonic anhydride, and fumaric anhydride, wherein the ion-sensitive polymer is dispersible and soluble in water; and wherein the fabric has an in-use tensile strength of at least 100 g/in after being soaked in a wetting solution containing more than 1% by weight monovalent and/or divalent ion concentration and less than about 10 weight percent of organic solvents, and a tensile strength of less than about 30 g/in after being soaked in water having a concentration of Ca 2+ and/or Mg 2+ ions of about 50 ppm for about one hour.