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HDPE Film Composition with Reduced Gauge Variation

IP.com Disclosure Number: IPCOM000012150D
Publication Date: 2003-Apr-11
Document File: 1 page(s) / 49K

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HDPE Film Composition with Reduced Gauge Variation

U.S. patent 5,962,598 to Mack et al. claims a high molecular weight, high density polyethlene, HMW HDPE, film composition characterized as being a free radical treated polyethylene film composition, said free radical treatment being accomplished by melt extruding said polytheylene composition in the presence of from about 0.5 to 6% by volume oxygen.  The claimed polyethylene composition was developed to improve bubble stability without reduction in tear strength of the film produced from the HMW HDPE resin.

At high extrusion rates and temperatures, good bubble stability can be achieved with a HMW HDPE polyethyleneproduced using bi-modal process technology.  This composition is similar to that claimed in the subject patent, but without free radical treatment. However, the film produced can show commercially unacceptable levels of gauge (thickness) variation.  It has been found that the gauge variation can be reduced to a commercially acceptable level with the addition of small amounts, 10 to 30 ppm, of peroxide to the intensive mixer/extruder at the resin production plant.  The use of peroxides such asDicumyl peroxide orDi(2-tert-butylperoxyisopropyl)benzene in the quantities indicated have been found to result in a polyethylene composition in which the gauge variation is reduced from about 50-75% to about  50% or less of the film thickness.  No reduction in film strength was found when these levels of peroxide were used.

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