| 摘要 |
PROBLEM TO BE SOLVED: To provide less heat shrinkage, heat resistant flexibility, transparency and antistatic properties and no curl after passing a copying machine by specifying the shrinkage differential value of a specific temperature range, the temperature range of a fine heat absorbing peak appearing before crystal melting by a differential scanning calorimeter, and a film haze. SOLUTION: This film for an overhead projector having a biaxially oriented polyester film has 0.3% or less of heat shrinkage of 30min at 150 deg.C, and always 0.01% or less of a shrinkage differential value dL/dT (L: length, T: temperature) in a temperature range of glass transition point to 200 deg.C in the differential curve of the true shrinkage in the longitudinal direction of the film obtained from the stretching or shrinkage amount at the time of temperature rise or fall by a thermomechanical characteristic tester. The differential heat absorbing peak appearing before the crystal melting by a differential scanning calorimeter is a range of a melting point to (melting point -30 deg.C). Further, the film haze at that time is 10% or less. |
