Patent attributes
The present invention is directed to a fibrous substrate made of chemically bonded fibers, where the fibers are bound with a polymeric binder in an amount which is sufficient to bind the fibers together to form a self-sustaining web, and where the binder is characterized as having a wet tensile strength of greater than 4500 grams per inch (g/in) when measured at a 20 percent add-on on Whatman #4 CHR chromatography paper which is drum dried for 90 seconds at 210 to 215° F. and cured for 2 minutes at 300 to 325° F. Preferably the level of free formaldehyde in the fibrous substrate is less than 15 ppm. The emulsion binders of the invention may be used to bind fibers together in a substrate; may be used to bind pigment, colors or other substances to a substrate; may be used as a backing material; or may be used to finish or surface-treat a substrate. Because of the high level of crosslinking, substrates bound, or treated with the emulsion polymer have excellent wet strength and good durability/weatherability and water/solvent resistance.
