Oriented polystyrene-based film having a syndiotactic structure

摘要

The present invention relates to an oriented polystyrene-based film comprising a polystyrene-based polymer having a syndiotactic structure,;Wherein the film has a thickness of 25 mu m or more and the rectangular sample of the oriented polystyrene based film has a value C expressed by the following formula (I) of 0.007 or less and a haze of the film is 1% or less, ) Of the film is in the range of -0.06 to -0.04. The oriented polystyrene-based film is characterized in that the plane orientation degree? P of the film is represented by -0.06 to -0.04.;here,;The rectangular sample;(A) a roll film; Wherein the rolled film is elongated in the longitudinal direction and has a width in a direction perpendicular to the longitudinal direction, wherein the rectangular sample has a length of 1000 mm on both sides in the longitudinal direction, and the other two sides have a length corresponding to the width Is the same; or;(B) a sheet having an arbitrary shape; Here, the rectangular sample is configured such that the area of the drawn rectangle is larger than the area of any other rectangle,;A _max is the square of the corresponding rectangular sample, and at the same time, four squares with one side of 100 mm are measured, and the molecular orientation angle is measured at any point within each square, and the molecular orientation direction of any reference square Is the maximum value among the angles between the molecular orientation direction of the reference square and the molecular orientation direction of the other three squares,;The HS _max is obtained by sharing the vertex of the corresponding rectangular sample from the corresponding rectangular sample, cutting one square sample having one side of 100 mm, and heating the corresponding square sample at 150 ° C. for 30 minutes by dry heating Wherein when the square specimen shrinks, the rate of dimensional change is displayed as a positive value,;R is a group represented by the following formula (II);, Where R is defined as 1 if the corresponding R exceeds 1;;Here, D is the distance (mm) between the center of the reference square before heating and the center of the square representing A _max ,;Here, N _X , N _Y , and N _Z are refractive indices in the longitudinal direction, the width direction, and the thickness direction of the film, respectively.