| abstract |
A uniaxially oriented, polyolefin film is prepared by melt blending a mixture of a polyolefin, an inert filler, and a processing aid such as calcium stearate, maintaining the moisture level in the melt blend below 700 ppm, casting a film, and uniaxially stretching the film at least about 2 times its original casting dimension in one direction until the film has a sufficient number of elongated, microporous voids in order to create a CO₂ and O₂ permeance in the range of 5,000 to 10,000,000 cc/100²-atm-day, the a film being used as a panel in a side of a controlled atmosphere packaging container that is otherwise substantially gas impermeable. |