To manufacture a biaxially oriented film in an existing biaxial orientation device used for polyester or the like by using bipolymerized amide composed of the specified amount of -caprolactam and aminododecanoic acid to be oriented in one direction and then oriented almost in the orthogonal direction.
In a polyamide oriented film manufactured by first stage orienting a substantially amorphous polyamide film in one direction and then second stage orienting the same in the direction almost orthogonal to the first stage orienting direction, bipolymerized polyamide composed of -caprolactam of 85-99.5wt.% and aminododecanoic acid of 0.5-15wt.%, more preferably, of -caprolactam of 95-99wt.% and aminododecanoic acid of 1-5wt.% is used as polyamide. Such a polyamide copolymer is polymerized in the normal process, namely the similar process of polymerization of -caprolactam, in which aminododecanoic acid is introduced together with -caprolactam and polymerized therein.
YAMASHITA ATSUSHI
SUGIMOTO KOJI
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