Polyethylene film
AssigneeNOVA Chemicals (International) S.A.
InventorsPatrick Lam, Victoria Ker, Charles Ashton Garret Carter, Benjamin Milton Shaw, Cliff Robert Baar, Alexei Kazakov, Ian Douglas McKay, Dusan Jeremic
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Abstract
Polyethylene films having a good balance of optical and mechanical properties are disclosed. The films are derived from ethylene copolymer compositions made with a suitably substituted phosphinimine catalyst. The ethylene copolymers have very narrow molecular weight distributions and broadened comonomer distributions.
Claims45
A film comprising a copolymer of ethylene and an alpha-olefin having from 3-10 carbon atoms wherein the film has a haze of ≦12%, a dart impact of ≦500 g/mil, an MD tear of ≦200 g/mil and wherein the copolymer has a density of from 0.916 g/cc to 0.930 g/cc, a melt index (I2) of from 0.3 to 3, a melt flow ratio (I21/I2)<20, a molecular weight distribution (Mw/Mn)≦2.5, and satisfies the condition:
- CDBI≦(β+25)/a-parameter;
- where β is the amount in weight % of the copolymer that elutes at 90° C. and above as determined by TREF, CDBI is the comonomer distribution breadth index determined by TREF, and the a-parameter is the Carreau-Yasuda shear exponent as determined by DMA at 190° C.
A film exhibiting a haze of ≦12%, a dart impact of ≧500 g/mil, an MD tear of ≧200 g/mil wherein said film comprises a copolymer of ethylene and an alpha-olefin having from 3-10 carbon atoms and which has a density of from 0.916 g/cc to 0.930 g/cc, an I21/I2<20, an a Mw/Mn of ≦2.5 and which has a TREF profile comprising i) less than 5 wt % of the copolymer represented at a temperature at or below 40° C., ii) a primary peak at a temperature T1, iii) a secondary peak at a temperature T2, and iv) from 10 to 30 wt % of the copolymer is represented at a temperature of from 90° C. to 105 C.°;
- wherein T2>T1 and the temperature difference between T1 and T2 is less than 20° C.
A film comprising a copolymer of ethylene and an alpha-olefin having from 3-10 carbon atoms wherein the film has a haze of ≦12%, a dart impact of ≧500 g/mil, an MD tear of ≧200 g/mil and wherein the copolymer has a density of from 0.916 g/cc to 0.930 g/cc, a melt index (I2) of from 0.3 to 3, a melt flow ratio (I21/I2)<20, a molecular weight distribution (Mw/Mn)≦2.5, and satisfies the condition:
- Tm≦(112.7+0.4β) where Tm is the peak melting temperature in ° C. as determined by DSC, and β is the amount in wt % of the copolymer that elutes at 90° C. and above as determined by TREF.
Dependencies are inferred from the claim text.