Abstract: A multilayer fibrous nonwoven mat containing at least one transition zone comprised of a mixture of the slurries used to form the layers on each side of the transition zone, the transition zone having a thickness of at least 1 percent of the thickness of the mat. At least one of the layers contains glass fibers. The multilayer mats are particularly useful as facers on gypsum wall board, insulating foam, a wood material and a broad range of other materials. The multilayer mats are made by a method that involves using a lamella in the forming box on a wet laid mat machine, between slurries, the lamella ending a significant distance prior to a moving forming wire. The transition zone or zones provide superior interlaminar shear strength and other properties compared to multilayer fibrous mats produced on wet laid machines having two or more separate forming boxes.

Abstract: Methods for making nonwoven fibrous mats that produce superior tear strengths in roofing products, and the mats produced by the method, are disclosed. The mats comprise glass fiber bonded together with a dried and cured mixture of aqueous urea formaldehyde resin and a self crosslinking copolymer of vinyl acrylic or polyvinyl acetate.