Roofing membranes using composite reinforcement constructions

Abstract

A composite substrate (10) is prepared for reinforcing a bituminous roofing material by securing together a carrier web (12) with a first set (14) of fiberglass rovings bundles and a second set (16) of fiberglass rovings bundles. The carrier web will have a pair of opposed planar surfaces. The web will define a machine direction and a cross machine direction for the substrate, with the first and second sets of rovings bundles each positioned in parallel relationship, with the longitudinal axes defined by the individual rovings of the two sets being in non-parallel relationship to each other when viewed normal to the plane of the web. The bundle sets are maintained in the spaced apart parallel relationships and the non-parallel angular relationship by the adhesive, stitching or other conventional method of securing which holds the substrate together. If a stitching machine is used, the preferred yarn (18) would be a polyester yarn. The preferred web is a woven polyester mat and the preferred rovings bundles will be 1800 yield or heavier. After preparation, this substrate is dipped in molten bituminous material to provide a web of reinforced roofing material in which the substrate is embedded in a continuous matrix of the bitumen.

Dependencies are inferred from the claim text.