| abstract |
An optical sheet material preferably used for the optical filter of display units, the substrate of liquid crystal display elements, the substrate of optical recording disks, and optical lenses; having the glass transition temperature and softening point of 130 °C or higher, the flexural elastic modulus of 50 to 1,000 kgf/mm2, the birefringence index of 30 nm or less, the yellowness index of 5 or less, the specific gravity of 1.5 or less, the deflection of 10 mm or less in a load-deflection test, and the thickness of 0.3 to 0.7 mm. |