| 摘要 |
PURPOSE: A polyester protective film for a polarizer is provided to ensure high light transmission, no interference nonuniformity, excellent optical characteristics and heat resistance, and water permeability, thereby being effective as a protective layer for a polarizer. CONSTITUTION: A polyester protective film comprises a dicarboxylic acid component and a diol component. The polyester film is the undrawn polyester film obtained by melt-extruding a polyester resin with a glass transition temperature of 100 °C or higher. The film has 20 nm or less of in-plane retardation at a wavelength of 590 nm. The dicarboxylic acid component is at least one selected from naphthalene dicarboxylic acid, dimethyl terephthalate, and terephthalic acid. The diol component is at least one selected from ethylene glycol, linear or branched diol with carbon number 3 or more, 1,4-cyclohexane methanol, cyclobutane diol, and isosorbide.
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