The accumulated draw ratio until the widening step (including the widening step) is equal to or greater than 1.6 (the draw ratio of the widening step when no other stretching step is performed before the widening step).
The moldable mixture is substantially free of formaldehyde, with low moisture content and high draw ratio.
The plastic film may be oriented at least in one direction with a draw ratio at least 4.
The film product is capable of being drawn at a draw ratio of from about 5.0:1 to about 10.0:1.
The high modulus polypropylene may contain a nucleating agent to facilitate the process of obtaining desired draw ratio.
In one embodiment, the water-swellable yarn has a stretch ratio of about 2 or more, where the stretch ratio is defined as the nominal unstretched diameter divided by the nominal stretched diameter.
In the method, the longitudinal drawing ratio (X) in the longitudinal drawing step is 2.8 to 3.5 times (inclusive), and the transverse drawing ratio (Y) in the transverse drawing step is 3.8 to 4.8 times (inclusive).
The preform (12) is heat-soften-drawn at 210°C. A drawing ratio is 1600.
The battery can is obtained by the process of ironing with an ironing ratio of 45-80%, and the exposure of the iron on the inner surface of the cylindrical side part of the battery can is suppressed.
The film product is also capable of being processed into a slit tape product.