Method of extruding polymer film onto a mat and products incorporating the resulting composite mat
A method of fabricating a polymer coated mat is disclosed to form a moisture barrier. The method includes moving a substrate mat along a processing path and heating the substrate mat to a predetermined temperature. A curtain of molten polymer is extruded through a slot die onto a surface of the heated substrate mat as the mat moves along the processing path to create a composite mat comprising a thin polymer film coating on at least one side of the substrate mat. The composite mat is then cooled in a controlled manner to cure and solidify the polymer film. The resulting composite mat may be used as a construction wrap, or it may be incorporated into other products such as an underlayment. A novel asphalt shingle may be fabricated using the composite mat in lieu of a traditional asphalt saturated mat or other substrate.
1. A method comprising the steps of:
conveying a fiberglass mat in a downstream direction along a processing path;
heating the fiberglass mat to a predetermined temperature to form a heated fiberglass mat;
extruding a layer of molten polymer directly onto the heated fiberglass mat while the polymer is still molten to form a molten polymer film on at least one surface of the heated fiberglass mat;
allowing the molten polymer film to bond to the heated fiberglass mat to form a composite mat;
cooling the composite mat to sufficiently solidify the molten polymer film to form a flat film of polymer such that: (i) the flat film forms a moisture barrier on the surface of the heated fiberglass mat, and (ii) the flat film does not stick when the composite mat is wound into a roll;
wherein cooling the composite mat comprises contacting the composite mat with at least one chilled roller, at least one chilled air blower, or a combination thereof; and
collecting the composite mat;
wherein the composite mat comprises a moisture resistant construction product.
2. A method as claimed in claim 1 wherein the step of heating the fiberglass mat comprises passing the fiberglass mat through an oven.
3. A method as claimed in claim 1 wherein the step of extruding a layer of molten polymer directly onto the heated fiberglass mat comprises positioning a die adjacent the surface of the heated fiberglass mat and ejecting molten polymer through the die directly onto the heated fiberglass mat.
4. A method as claimed in claim 3 wherein the die is a slot die.
5. A method as claimed in claim 3 further comprising the step of delivering polymer to the die through an extruder and melting the polymer as it moves through the extruder.
6. A method as claimed in claim 5 further comprising the step of delivering the polymer to the extruder in the form of pellets that are subsequently melted as they are conveyed through the extruder.
7. A method as claimed in claim 1 wherein the step of allowing the film of molten polymer to bond to the heated-fiberglass mat comprises allowing the film of molten polymer to remain in contact with the heated fiberglass mat for a predetermined length of time until the polymer begins to cool and cure.
8. A method as claimed in claim 1 further comprising passing the composite mat over at least one chilled roller and passing the composite mat under at least one chilled roller.
9. A method as claimed in claim 1 further comprising controlling the rate of extrusion of molten polymer relative to the speed at which the fiberglass mat is conveyed to extrude a layer of molten polymer of a predetermined thickness onto the fiberglass mat.
10. A method as claimed in claim 9 wherein the predetermined thickness is less than about 12 microns.
11. A method as claimed in claim 10 wherein the predetermined thickness is between about 3 microns and about 10 microns.
12. A method as claimed in claim 11 wherein the predetermined thickness is between about 5 microns and about 6 microns.