Polyethylene fabric with improved physical properties and method for making thereof
View Patent ↗An improved polyethylene fabric comprises polyethylene fabric or yarn that is manufactured by mixing HDPE (typically in pellet form) with pellets of cyclic-olefin polymers (COCs) in a ratio of up to 40% by weight of the layer. This mixture is then extruded in ways known to those skilled in the art. The resulting HDPE has superior stress and strain characteristics over a wider range of pressures and temperatures than conventional HDPE. The improved polyethylene fabric of the present invention is useful in applications where structural integrity is required and where pressure and temperature are a factor. For example, improved HDPE scrims of the present invention can be used as the reinforcing structure for irrigation hose or building fabric.
1. A polyethylene fabric having improved stretch and strain properties, comprising:
a reinforcing layer comprising a woven scrim made from a mixture of high density polyethylene and cyclic-olefin copolymers,
wherein the reinforcing layer is produced from a film slit into tapes wherein the tapes have a denier of 1600;
wherein the cyclic-olefin copolymer is formed by a process comprising polymerizing 2 norbornene with ethylene in the presence of a single site catalyst,
wherein the cyclic-olefin copolymer has a glass transition temperature (Tg) ranging from about 60° C. to about 70° C.,
wherein the cyclic olefin copolymer has melt flow rate of about 1.0 at 190° C.; and
wherein the high density polyethylene has a melt index ranging from about 0.65 g/10 min to about 0.75 g/10 min.
2. The fabric according to claim 1 , wherein the reinforcing layer comprises from about 60% to about 99% by weight of the layer HDPE and from about 1% to about 40% by weight of the layer cyclic-olefin copolymers.
3. The fabric of claim 1 further comprising a coating layer disposed on at least one surface of the reinforcing layer.
4. The fabric according to claim 3 , wherein the coating layer comprises polyethylene.
5. The fabric according to claim 4 , wherein the polyethylene is selected from the group consisting of ethylene methacrylate (EMA), low density polyethylene (LDPE), and linear low density polyethylene (LLDPE).
6. The fabric of claim 3 , wherein the coating is disposed on both surfaces of the reinforcing layer.
7. The fabric of claim 4 , wherein the coating further comprises UV resistance additives.
8. The fabric of claim 4 , wherein the coating further comprises color.
9. The fabric of claim 4 , wherein the coating further comprises anti-static coating.
10. The fabric of claim 1 , wherein the cyclic-olefin copolymer is selected from a group consisting of polynorbornene, polydimethyloctahydro-naphthalene, polycyclopentene, and poly(5 methyl)-norbornene.
11. The fabric of claim 1 , wherein the cyclic-olefin copolymer is a non-polar fully amorphous cyclic olefin copolymer.
12. The fabric of claim 1 , wherein the single site catalyst is a metallocene catalyst.
13. The fabric of claim 1 , wherein the high density polyethylene has a melt index of 0.65 g/10 min.
14. The fabric of claim 1 , wherein the high density polyethylene has a melt index of 0.72 g/10 min.
15. The fabric of claim 1 , wherein the high density polyethylene has a density ranging from about 0.955 g/cm 2 to about 0.962 g/cm 2 .
16. The fabric of claim 1 , wherein the high density polyethylene has a density of about 0.956 g/cm 2 .
17. The fabric of claim 1 , wherein the high density polyethylene has a density of about 0.962 g/cm 2 .
18. A tensioned building fabric comprising the reinforcing layer of claim 1 , wherein the reinforcing layer is prepared by a process comprising the steps of:
mixing HDPE pellets and COC pellets to form a mixture;
extruding the mixture to form a sheet film;
slitting the film into tapes; and
forming a woven scrim from the tapes; whereby the woven scrim forms the reinforcing layer for the fabric.
19. An irrigation hose comprising the reinforcing layer of claim 1 , wherein the reinforcing layer is prepared by:
mixing HDPE pellets and COC pellets to form a mixture;
extruding the mixture to form a sheet film;
slitting the film into tapes; and
forming a woven scrim from the tapes; whereby the woven scrim forms the reinforcing layer for the irrigation hose.