1. Field of the Invention
This invention relates to a wet-laid method of making glass fiber mats, and more particularly, to an improved process for making high-strength glass fiber mats which are particularly useful for roofing products, including built up roofing membranes and systems.
2. Description of the Prior Art
Roofing products which use glass fiber mats in place of organic felts require mats having high-strength properties. Built up roofing membranes and systems, especially, need mats which have excellent tear resistance. Unfortunately, the glass fiber mats of the prior art, which rely upon continuous strands or elongated, rod-like bundles of fibers as reinforcing agents, often are expensive and more difficult to make, and do not possess these high-strength properties, particularly for built up roofing application. Such glass mats are described in a number of U.S. Pat. Nos., including 3,634,054; 3,853,683; 4,112,174; 4,129,674; 4,135,022 and 4,135,029.
Therefore, it would be of considerable advantage to the roofing industry to provide a new and improved method of making high-strength glass fiber mats adaptable for built up roofing membranes and systems, by an economical, wet-laid process using inexpensive, chopped bundles of glass fibers as the raw material for the mat.