A common method of production of fiber-reinforced roofing products of bituminous materials is to pull a reinforcing mat through a dip tank or bath of molten bituminous material. The mat can be an organic felt, a glass fiber mat or a synthetic mat such as a polyester mat, or any combination of these. The mat can be pulled through a path defined by a series of rolls and can include turning around one or more rolls which are positioned within the tank of molten bituminous material. The product typically produced by this type of process is a roofing membrane although other products, such as driveway underlayment, can also be produced.
An important consideration in producing fiber reinforced mats of bituminous material is the efficiency of the impregnating process. The process must be run slow enough so that the mat becomes completely impregnated or saturated. Incomplete saturation results eventually in a failure in the product application, such as a roofing failure. The economics of the process requires that the process be run as fast as possible to reduce costs. There is a need for improvements which can increase the level of efficiency of impregnation, while enabling an increase in throughput to reduce operating costs.
Another important consideration in producing fiber reinforced mats of bituminous materials is the positioning of the mat within the bituminus material in the final product. For example, the mat could be positioned near the top of the product, in the middle of the product, or at the bottom of the product. Some products, such as a roofing membrane for use in a two-layer roofing system in which the first layer is torched, require the reinforcement to be positioned in the middle of the product. If the roofing membrane is to be topped with granules, then the mat should be near the top of the product, but not at the very top. Other products, such as a roofing membrane used in a single-ply application, require the reinforcing mat to be positioned at the top of the product in order to provide the best resistance to ultraviolet light. Therefore, it would be useful to have a process for making reinforced products which would enable the positioning of the reinforcing mat at any desired height within the product.