| 摘要 |
PROBLEM TO BE SOLVED: To provide a film for a heat sensitive stencil printing base paper, in which both the clear printing of a character and the clear solid printing are developed, neither ununiform printing thickness nor ununiform shading develops, wrinkle are hard to develop, durability and preservability are excellent and a printing sensitivity can be kept unvaried especially even in high speed printing. SOLUTION: This film is biaxially oriented polyester, film, which is made of a polyester composition including 40 wt.% or more of a polybutylene terephthalate copolymer having a thickness of 0.2 to 7.0μm, a melting point (Tm) of 180 deg.C or higher and 230 deg.C or lower, a planar orientation coefficient (Ns) of 0.120 or more and 0.145 or less and the melt viscosity satisfying formula (1): 200<=V(Tm+20)-V(Tm+40)<=700, wherein V(Tm+20) represents a melt viscosity (poise) in shearing speed of 1,000 s-1 at a temperature, which is higher by 20 deg.C than the melting point of the film and V(Tm+40) represents a melt viscosity (poise) in shearing speed of 1,000 s-1 at a temperature, which is higher by 40 deg.C than the melting point of the film.
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