| 摘要 |
<p>PURPOSE:To improve weather resistance, tear strength, and heat resistance by incorporating a dichroic dye in the film so as to arrange that the birefringence of the film in a plane after stretching and thermal fixing exceeds 0.110. CONSTITUTION:The birefringence in a plane after stretching and thermal fixing is arranged to be >=0.110 by incorporating a dichroic dye in the film. Polyethylene naphthalate mentioned here is polymer having constituting units constituted substantially of ethylene-2,6-naphthalate unit, but ethylene-2,6-naphthalate polymers modified with a small amt. (for example, <=10mol%, pref. <=5mol%) third component may be also included. The intrinsic viscosity of polyethylene naphthalate is >=0.40, pref. 0.45-0.90, because the mechanical strength is deteriorated if the degree of polymn. of polyethylene naphthalate is too low. By this constitution, the heat resistance, heat contraction, mechanical strength as well as degree of polarization are improved.</p> |
