Polyethylene fibers and spunbonded fabric or web
AssigneeThe Dow Chemical Company
InventorsStephen P. Krupp, Edward N. Knickerbocker, John O. Bieser
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Abstract
Blends of high molecular weight linear polyethylene and low molecular weight linear polyethylene provide improved fiber-forming capabilities over that found with either polymer taken alone. Preferably at least one of the polymers used in the blend is a linear low density polyethylene, LLDPE, which is a linear polyethylene comprising ethylene copolymerized with an amount of a higher alpha-olefin which causes the density of the copolymer to be less than that of a homopolymer made using the same process and catalyst. The higher alpha-olefin can be at least one in the C.sub.3 -C.sub.12 range, preferably in the C.sub.4 -C.sub.8 range.
Claims9
A spunbonded fabric of web prepared from a blend of linear polyethylenes suitable for spunbonding at throughput rates of about 1.0 to about 1.2 grams/minute/hole, at linear spinning velocities of at least about 3500 meters per minute, to produce fiber sizes of less than 3.0 denier/filament, said blend comprising
- high molecular weight linear polyethylenes having a MFR value within the range between about 0.5 to 25 g/10 min. and a density above about 0.91 g/cm.sup.3, and
- low molecular weight linear polyethylene having a MFR value within the range of greater than 25 to about 300 g/10 min. and a density above about 0.91 g/cm.sup.3,
- said spunbonded fabric or web being prepared therefrom and exhibiting improved properties over that similarly prepared from the high molecular weight linear polyethylene alone.
In a process wherein molten LLDPE polymer is spunbonded to make a web or fabric,
- the improvement wherein the LLDPE comprises a blend of high molecular weight LLDPE and low molecular weight LLDPE spunbondable at a throughput rate of about 1.0 to about 1.2 grams/minute/hole, using a linear spinning velcocity of at least about 3500 meters per minute, and at a fiber size of smaller than 3 denier/filament, thereby producing a web or fabric having improved strength over that obtained by similarly spunbonding a web or fabric of the high molecular weight LLDPE alone,
- wherein said high molecular weight LLDPE has a MFR below 25 g/10 min., and
- wherein said low molecular weight LLDPE has a MFR above 25 g/10 min.
Dependencies are inferred from the claim text.