Films with excellent machine direction (MD) tear properties comprise at least
one layer made from a polymer comprising:
- (A) at least 50 weight percent (wt %) propylene; and
- (B) at least 5 wt % ethylene and/or one or more unsaturated comonomers.
Representative of component (B) unsatuarated comonomers are the C4-20
-olefins, C4-20 dienes, styrenic compounds, and the like. Preferably,
the film has at least one of a (i) haze value of less than about 10, (ii) 45 degree
gloss of greater than about 65, and (iii) dart value of greater than about 100
g/mil. In one preferred embodiment, the layer comprises a compolymer characterized
as having at least one of the following properties: (i) 13C NMR peaks
corresponding to a regio-error at about 14.6 and about 15.7 ppm, the peaks of about
equal intensity, (ii) a B-value greater than about 1.4 when the comonomer content,
i.e., the units derived from ethylene and/or the unsaturated comonomer(s), of the
copolymer is at least about 3 wt %, (iii) a skewness index, Six, greater
than about -;1.20, (iv) a DSC curve with a Tme that remains essentially
the same and a Tmax that decreases as the amount of comonomer, i.e.,
the units derived from ethylene and/or the unsaturated comonomer(s), in the copolymer
is increased, and (v) an X-ray diffraction pattern that reports more gamma-form
crystals than a comparable copolymer prepared with a Ziegler-Natta (Z-N) catalyst.
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