Process for in-line extrusion of coating onto roofing shingles during manufacturing and roofing shingles made by the process
A process for in-line extrusion of polymeric coatings onto roofing shingles during manufacturing includes moving a web of shingle substrate material in a downstream direction and extruding a liquefied coating of polymeric material onto at least one surface of the moving web to form a thin film. The liquefied coating may be a molten polymeric material that forms a thin film on a back surface of the shingle material to prevent sticking and eliminate the need for a traditional back dusting with material such as powdered stone. The polymeric film further may be applied to the substrate material in lieu of a saturation coating of asphalt, thus reducing cost and weight while providing a comparable moisture barrier and a lighter more flexible shingle.
1. A method of fabricating roofing shingles comprising the steps of:
(a) conveying a mat of substrate material having a first and a second surface in a downstream direction;
(b) ejecting a stream of molten polymeric material directly onto the first surface of the mat of substrate material as the mat is conveyed in the downstream direction to deposit a film of molten polymeric material on the first surface;
(c) cooling the film of molten polymeric material to cure the film, bond the polymeric material to the mat of substrate material, and form a waterproof coating on the mat of substrate material;
(d) coating the second surface of the mat of substrate material with a bituminous coating that is at least partially molten;
(e) embedding ceramic-coated granules into the bituminous coating to form a protective layer and to produce roofing shingle stock;
(f) cutting the roofing shingle stock to form individual shingles; and
(g) bundling the individual shingles for storage and shipment;
step (b) being performed before step (d); and
step (c) is conducted before step (e).
2. A method of fabricating roofing shingles as claimed in claim 1 where in step (a) the mat of substrate material comprises a glass mat.
3. A method of fabricating roofing shingles as claimed in claim 1 where in step (a) the mat of substrate material comprises an organic felt mat.
4. A method of fabricating roofing shingles as claimed in claim 1 wherein the first surface of the mat of substrate material will become back surfaces of shingles fabricated by the method.
5. A method of fabricating roofing shingles as claimed in claim 1 wherein the second surface of the mat of substrate material will become top surfaces of shingles fabricated by the method.
6. A method of fabricating roofing shingles as claimed in claim 1 further comprising saturating the mat of substrate material with a bituminous material prior to step (b).
7. A method of fabricating roofing shingles as claimed in claim 1 wherein step (c) comprises subjecting the film of polymeric material to an air stream.
8. A method of fabricating roofing shingles as claimed in claim 1 wherein step (c) comprises passing the mat of substrate material over chilled rollers.
9. A method of fabricating roofing shingles as claimed in claim 1 wherein step (b) comprises ejecting the stream of molten polymeric material as a curtain.
10. A method of fabricating roofing shingles as claimed in claim 9 wherein step (b) further comprises forcing the molten polymeric material through a slot die toward the first surface of the mat of substrate material.
11. A method of fabricating roofing shingles as claimed in claim 1 further comprising the step of ejecting a stream of molten polymeric material onto at least a portion of the second surface of the mat of substrate material.
12. A method of fabricating roofing shingles as claimed in claim 11 further comprising ejecting a stream of molten polymeric material onto the portion of the second surface of the mat of substrate material that will become a headlap portion of shingles cut from the roofing shingle stock.