High-strength glass fiber mat particularly useful for roofing products

Abstract

What is provided herein is a glass fiber mat having a novel structure and high-strength properties which is particularly useful for roofing products, including built up roofing membranes and systems. The glass mat of the invention is comprised of two fibrous components, namely, individual filament glass fibers and extended glass fiber elements, which are formed in situ in a wet-laid process from original bundles of glass fibers. The individual filaments appear by conventional filamentation of the bundles. The extended fiber elements, however, are formed by longitudinal extension of a given bundle whose fibers are connected longitudinally. Thereby the effective length of a fiber element is very much greater than the length of the fibers therein. The fiber elements are further characterized by a non-uniform diameter, as contrasted to the fibers themselves, being thicker in the mid-section of the element where connection of fibers is maximized, and tapered towards its ends, where fiber connection is at a minimum. The extended fiber elements preferably predominate by weight of the fibrous content of the mat over the individual filaments. The desired ratio of the two components is achieved by using bundles whose fibers have a long length, and by very gentle agitation of the dispersion slurry for a short period of time.