Polyolefin compositions with balanced shrink properties

DETAILED DESCRIPTION OF THE INVENTION Double bubble and trapped bubble biaxial orientation methods can be simulated on a laboratory scale using a T.
M.
Long stretcher which is analogous to a tenter frame device.
This device can orient polyolefin films in both the monoaxial and biaxial mode at stretching ratios up to at least 5:1.
The device uses films having an original dimension of 2 inches.
times.
2 inches.
Biaxial stretching is usually performed by stretching in the machine direction and transverse direction of the film simultaneously, although the device can be operated to stretch sequentially.
The residual crystallinity of polyolefin interpolymers (measured using a DSC partial area method) can be used to characterize the nature of polyolefin film at the orientation temperature.
In general, it preferred to orient polyolefin films at a an orientation temperature where the residual crystallinity of the film is as high as possible.
Such an orientation will generally be only a few degree above that temperature where the film can no longer be successfully oriented.
That is, about 5.
degree.
C.
above, preferably about 3.
degree.
C.
above, more preferably about 2.
5.
degree.
C.
above the lowest stretch temperature (defined herein above) is considered herein to be the optimum or near-optimum stretching or orientation temperature for the particular film.
Stretching temperatures less than about 2.
5.
degree.
C.
above the lowest stretch temperature are not preferred because they tend to yield inconsistent results, although such inconsistencies tend to depend on specific equipment and temperature control capabilities.
However, for proper comparison of various films, an orientation temperature should be selected such that the residual crystallinity at orientation is approximately the same for each film.
That is, although wide orientation windows are desired, selection of the actual orientation temperature to be employed should never be arbitrary.
The density differential between the at least one first ethylene polymer component (A) and the at least one second ethylene polymer component (B) is generally in the range of from about 0 to about 0