Net structure and method of making
The present invention concerns an extrusion formed reticulated web, mesh or netting including reticulated hook fasteners for use with hook and loop fasteners the polymer netting comprising two sets of strands at angles to each other. The first set of strands are a plurality of oriented (molecular orientation created by stretching) strands extending in a first direction and are generally mutually parallel and linear. The second set of strands are a plurality of substantially parallel strands attached only to a first face of the first set of oriented strands. The first set of oriented strands occupy a first planar cross-sectional area in the thickness direction of the formed netting. Said second set of oriented strands occupy a second planar cross-sectional area in the thickness direction of the formed netting. Preferably, these first and second planar cross-sectional areas are substantially mutually exclusive and are abutting. The polymer netting is preferably made by extruding a thermoplastic resin through a die plate, which die plate is shaped to form a base film layer and spaced ridges or ribs projecting from a surface of the base layer. The spaced ridges or ribs formed by the die form the first set of strands forming the reticulated mesh or netting. The second set of transverse strands are formed by transversely cutting the base layer at spaced locations along a length, at a transverse angle to the ridges or ribs, to form discrete cut portions. Subsequently longitudinal stretching of the ridges (in the direction of the ridges or the machine direction) separates these cut portions of the backing, which cut portion then form the second set of spaced apart strands of the reticulated mesh or netting.
1. A polymer netting comprising a plurality of oriented thermoplastic strands extending in a first direction, the first set of oriented strands having a first face and a second face and two side faces, a second set of strands integrally formed with the first set of oriented strands and attached only to said first face of said oriented strands, wherein said first set of oriented strands occupy a first planar cross-sectional area in the thickness direction of the netting and said second set of strands occupy a second planar cross-sectional area in the thickness direction of the netting and said first and second planar cross-sectional areas are substantially mutually exclusive and abutting and said second set of strands has substantially parallel side faces such that the strand width of the second set of strands at crossover points of the two sets of strands is substantially the same as the strand width of the second set of strands between the crossover points, and wherein said second set of strands have surface structures on said first faces of the strands.
2. The polymer netting of claim 1 wherein said second set of strands are mutually parallel and have a first face and a second face and are substantially coextensive.
3. The polymer netting of claims 2 wherein said second set of strands second faces are attached to said first set of oriented strands at their crossover points.
4. The polymer netting of claim 1 wherein said second set of strands have a substantially rectilinear cross-section.
5. The polymer netting of claim 4 wherein adjacent strands of said second set of strands have a substantially identical cross-sectional shape in said first direction.
6. The polymer netting of claim 1 wherein said second set of strands are linear.
7. The polymer netting of claim 1 wherein said surface structures are stems extending upward.
8. The polymer netting of claim 7 wherein said stem structures have hook elements projecting in at least one direction.
9. The polymer netting of claim 8 wherein said hook elements extend in the direction of the second set of strands.
10. The polymer netting of claim 8 wherein said hook elements extend in two or more directions and form a mushroom.
11. The polymer netting of claim 1 wherein said first set of strands have surface structures on said second face of said strands.
12. The polymer netting of claim 11 wherein said surface structures are stems extending upward.
13. The polymer netting of claim 12 wherein said stem structures have hook elements projecting in at least one direction.
14. The polymer netting of claim 13 wherein said hook elements extend in a direction perpendicular to said first direction.
15. The polymer netting of claim 1 wherein said polymer is a thermoplastic polymer.