POLYIMIDE FILM, METHOD OF PREPARING POLYIMIDE FILM, OPTICAL DEVICE INCLUDING POLYIMIDE FILM

摘要

A colorless transparent polyimide having a thickness of about 1 micrometer to about 250 micrometers, an average coefficient of thermal expansion measured in a machine direction and a transverse direction of less than or equal to about 80 parts per million/° C., an average in-plane retardation of less than or equal to about 20 nanometers, an average Yellowness Index of less than or equal to 6, and a transmittance for light at a wavelength of 370 nanometers to 740 nanometers of greater than or equal to about 80%.

主权项

1. A colorless transparent polyimide film having:
a thickness of about 1 micrometer to about 250 micrometers; an average coefficient of thermal expansion measured in a machine direction and a transverse direction of less than or equal to about 80 parts per million/° C., measured using thermo-mechanical analyzer at a temperature range of 50° C. to 250° C. by a method comprising: heating the film from 25° C. to 260° C. at a heating rate of 10° C./minute, cooling the film to 40° C. at a cooling rate of 10° C./min, and heating the film from 25° C. to 250° C. at a heating rate of 10° C./minute; an average in-plane retardation of less than or equal to about 20 nanometers, measured by Axoscan at a wavelength of 550 nanometers throughout the area of the film; an average Yellowness Index of less than or equal to 6, measured using a spectrophotometer, and a transmittance for light at a wavelength of 370 nanometers to 740 nanometers of greater than or equal to about 80%, measured by using CIE standard, Illuminant D65.