Process for producing laminated bituminous roofing membrane

A process for producing a self-adhesive, multi-layer, laminated, bituminous, roofing membrane suitable for cold application to a substrate, which comprises the step of:

• a. continuously moving a continuous web of a flexible base sheet through a first coating device and therein coating at least a part of at least one surface of said base sheet with a continuous surface coating layer of substantially uniform thickness of hot molten roofing bitumen in a viscous liquid state, said roofing bitumen having the property that it is substantially solid at amibient application temperature to form a waterproof layer on said base sheet;
• b. separately from step (a) but simultaneously therewith, continuously moving a continuous web of a flexible release sheet through a second coating device and therein coating substantially the entirety of only one releasable surface of said release sheet with a continuous surface coating layer of substantially uniform thickness of hot molten compound bitumen in a viscous liquid state, said compound bitumen consisting essentially of bitumen and about 5 to 95 percent by weight of substance selected from the group consisting of rubber, thermoplastic resin and mixtures thereof, said compound bitumen having the property that it possesses a high tackiness at ambient application temperature;
• c. immediately after steps (a) and (b) and while said surface coating layers on the coated webs obtained in steps (a) and (b) are still in a molten state, continuously conjointly moving said coated webs around and in supported relationship on a circumferentially elongated portion of the periphery of a roller with one of said coated webs being disposed with its sheet in surface contact with said circumferentially elongated portion of the periphery of said roller and with its surface coating layer facing outwardly away from said roller and with the other of said coated webs having its surface coating layer disposed in face-to-face opposing relationship to said surface coating layer of said one coated web and with its sheet being disposed outwardly therefrom, and drawing said other web into contact with said one web and thereby uniting said surface coating layers in direct face-to-face contact as said webs move together around said circumferentially elongated portion of said roller, said uniting of said surface coating layers being effected in the absence of an external compression force applied to the sheet of said other web whereby to form a unitary roofing membrane consisting essentially of the products of steps (a) and (b) wherein said coating layers are between said base sheet and said release sheet and are united thereto and to each other;
• and then
• d. continuously moving said unitary roofing membrane through a cooling device whereby to solidify said coating layers.