| 摘要 |
PURPOSE: To provide an inexpensive material with which a film having a little heat contraction, excellent planeness, and low cleaving property can be obtained without increasing the cost and problems such as contraction, curling, slacking, and cleaving do not occur also in OHP and electric insulating material. CONSTITUTION: In a biaxially oriented film consisting of polyester, a heat contraction factor of the film at 190 deg.C for 20 minutes in the direction of machine is 1.0% or below and 0.3% or below at 150 deg.C for 30 minutes, and a surface crystal size by wide angle X-ray diffraction (hereinafter called X-ray) is 60-80 angstram. |
