| 摘要 |
PROBLEM TO BE SOLVED: To provide a polyester film excellent in uniform diffusion properties of light and heat-resistant dimensional stability and also in luminance, and is suitable as a base plate for light-diffusion plates of liquid crystal display devices. SOLUTION: There is provided a biaxially oriented polyester film for light- diffusion plates, which (1) comprises an aromatic polyester whose primary repeating unit is ethylene-2,6-naphthalene-dicarboxylate, (2) has a heat-shrinkage rate of 0.3% or less when heat-treated for 30 minutes at 105 deg.C under no load, in two directions intersecting perpendicularly to each other within the film surface, (3) has a dimensional change rate of 1.0% or less, in two directions intersecting perpendicularly to each other within the film surface, under a load of 0.37 MPa based on the crosssectional area of the film and in the temperature range of from 30 deg.C to 150 deg.C, (4) has a density of 1.350 g/cm3 or more, (5) has a total light transmission of 87% or more, (6) has a haze value of not greater than 1.5%, and (7) has a thickness in the range of 50-130 μm. |
