US Patent 7977259 Roofing underlayment and method of producing same

A roofing membrane suitable for use as an underlayment comprising a flexible, non-woven mat of polymeric fibers which are substantially uniformly dispersed throughout the non-woven mat and thermally bonded together at the points of intersection by the polymeric materials of the fibers, the mat having a top side and a bottom side, a layer of an asphaltic material being disposed on the bottom side of the mat to provide a coated mat and a liquid parting agent applied to the top side of the mat.