Synthetic fabric having slip resistant properties and method of making same

1. A method comprising:

forcing a polymer resin through a spinerette die onto a moving belt to form a sheet made of randomly oriented entangled fibers;

calendering the sheet between a pair of heated rolls, one of the rolls being an engraved roll engraved with a pattern of cavities defined therein, to produce a calendered sheet,

wherein the calendered sheet comprises:

a) a plurality of elevated portions of random unbonded fibers, and

b) channels comprising bonded fibers between the plurality of elevated portions;

laminating a scrim layer and the calendered sheet with a resin lamination layer,

wherein the resin lamination layer:

a) is between the calendered sheet and scrim layer, and

b) extends at least from a first end of the calendered sheet to a second end of the calendered sheet opposite the first end, and

wherein the scrim layer extends at least from the first end of the calendered sheet to the second end of the calendered sheet, and

applying a resin coating layer to the scrim layer, thereby to form a roofing underlay,

wherein the resin coating layer extends at least from the first end of the calendered sheet to the second end of the calendered sheet.

2. The method of claim 1 , wherein the other one of the heated rolls is a smooth roll having a smooth cylindrical outer surface.

3. The method of claim 1 , wherein the heated rolls are heated to a temperature and exert a pressure on the sheet sufficient to form the channels and the elevated portions.

4. The method of claim 2 , wherein each of the engraved roll and the smooth roll are maintained at a different temperature.

5. The method of claim 4 , wherein the engraved roll is maintained at a temperature between 142-146 degrees Celsius, and the smooth roll is maintained at a temperature between 137-140 degrees Celsius.

6. The method of claim 1 , wherein each of the cavities has a bottom surface at a depth greater than a height of a top surface of the elevated portions above a top surface of the channels such that an air pocket is formed between the top surface of the elevated portions and the bottom surface of the cavities during calendering of the sheet.

7. The method of claim 6 , wherein the height is greater than 0.5 mm.

8. The method of claim 4 , wherein adjacent cavities are separated by at least 0.5 mm.

9. The method of claim 1 , wherein the polymer resin comprises polypropylene, polyethylene, polyester or nylon.

10. The method of claim 1 , wherein the scrim layer comprises a woven material.

11. The method of claim 10 , wherein the woven material comprises at least one of polyethylene or polypropylene.

12. The method of claim 1 , wherein the resin lamination layer comprises a polymer.

13. The method of claim 1 , wherein the resin lamination layer comprises a combination of polyethylene and polypropylene.

14. The method of claim 13 , wherein laminating the scrim layer and the calendered sheet with the resin lamination layer comprises:

extruding, between the calendered sheet and the scrim layer, a lamination polymer through a die; and

pressing together, with at least two rollers, the calendered sheet, the extruded lamination polymer, and the scrim layer.

15. The method of claim 1 , further comprising:

trimming the roofing underlay to a length.

16. The method of claim 15 , further comprising:

winding the length of the trimmed roofing underlay on a core.

17. The method of claim 1 , wherein the resin coating layer comprises a film.

18. The method of claim 17 , wherein the film comprises at least one of polyethylene and polypropylene.

19. The method of claim 1 , wherein the resin lamination layer comprises:

between 5% and 30% low-density polyethylene, and

polypropylene.

20. The method of claim 19 , wherein the resin lamination layer further comprises a UV additive.