| 摘要 |
PROBLEM TO BE SOLVED: To form the perforation diameter in compliance with the variation of energy level and improve the tone properties by using a biaxially oriented polyester film formed on a polyester film having the specified melting point and thickness and the specified integral value of thermal shrinkage found by a specified formula. SOLUTION: In a heat-sensitive stencil printed base paper polyester film perforated by the flash emission, a biaxially oriented polyester film having the melting point set at 220 deg.C or above and the thickness set as 0.2-4μm and also having the integral value of thermal shrinkage stress found by a formula and satisfying 1000>=(Mmd+Mtd)/2>=100 is used. In the formula, M represents the integral value of thermal shrinkage stress, s(t) represents the thermal shrinkage stress Mpa at the temperature(t), To represents the temperature of starting the thermal shrinkage stress, Tm represents the temperature of thermal shrinkage stress from the starting temperature to the zero(0)MPa again, Mmd represents the integral value of thermal shrinkage stress in the longitudinal direction of a film and Mtd represents the integral value of thermal shrinkage stress in the width direction of the film. |
