PROCESS FOR PRODUCING LIGHT-DIFFUSING FILM AND LIGHT-DIFFUSING FILM

摘要

[PROBLEMS] To provide a process for producing a light-diffusing film which retains the excellent heat resistance and mechanical strength inherent in biaxially stretched films and is excellent in light transmittance and light-diffusing properties; and a light-diffusing film obtained by the process. [MEANS FOR SOLVING PROBLEMS] The process is for producing a light-diffusing film comprising a light-diffusing layer obtained by biaxially stretching an unstretched sheet made of a mixture comprising 50-99 parts by mass of a crystalline polyester and 1-50 parts by mass of a light-diffusing additive, and is characterized in that the biaxial stretching is conducted in a stretch ratio of 2.5 or higher in each of the machine direction and transverse direction at a stretching rate lower than 300% per second. The light-diffusing film produced by the process is characterized by having a total light transmittance of 85% or higher, a haze of 50% or higher, a dimensional change at 150°C in each of the machine direction and transverse direction of 3% or smaller, and a tensile strength in each of the machine direction and transverse direction of 100 MPa or higher.