| 摘要 |
Shrink film having a desirable balance of properties is manufactured from a polyethylene blend composition having a fractional melt index and a molecular weight distribution of from about 2.5 to about 7. The blend composition comprises a first blend component that is made with a single site catalyst and has a molecular weight of greater than about 140,000 and a first density, d1. The blend composition also contains a second blend component having a lower molecular weight and a second density, d2, that is greater than the density of d1 in an amount of from about 0.018 to about 0.032 g/cc. The films of this disclosure may be used, for example, as an overwrap or pallet wrap to protect goods during shipping and in food packaging applications (such as shrink wrap for frozen poultry). |
| 主权项 |
1. A shrink film prepared comprising a polyethylene blend composition having a density of from about 0.920 to about 0.950 g/cc and a melt index, I2, of from about 0.1 to about 0.9 grams per 10 minutes, and a molecular weight distribution Mw/Mn, of from about 2.5 to about 7; wherein said polyethylene blend composition comprises
1) from about 30 to about 50 weight % of a first polyethylene composition having a first weight average molecular weight, Mw1, of greater than about 140,000, a first molecular weight distribution, Mw1/Mn1, of from about 1.7 to about 3, and a first density d1, and; 2) from about 70 to about 50 weight % of a second polyethylene composition having a second weight average molecular weight, Mw2, that is greater than about 24,000 and less than said first average molecular weight Mw1; a second molecular weight distribution, Mw2/Mn2, of from about 1.7 to about 3 and a second density d2; with the provisos that 1) said d2 is greater than said d1, and 2) d2-d1, is from about 0.018 g/cc to about 0.032 g/cc, and; wherein density is measured according to ASTM D792 and melt index is measured according to ASTM D1238 when conducted at 190° C. using a 2.16 kg weight. |
