BASE FILM FOR MEMBRANE SWITCH AND MEMBRANE SWITCH

摘要

There is provided a membrane switch film comprising polyethylene-2,6-naphthalenedicarboxylate as the major component and having excellent handling properties and durability, and particularly a film which is suitable for a membrane switch to be used in automobile interior devices which are potentially exposed to high temperature. The film is a membrane switch film having a refractive index in the range of 1.770-1.790 on both surfaces in either or both the film processing direction and the widthwise direction and an absolute value of no greater than 0.015 for the difference between the refractive indexes of both surfaces, or having a melting sub-peak temperature of between 220 DEG C and 250 DEG C as measured with a differential scanning calorimeter (DSC) and an absolute value of no greater than 6 DEG C for the difference between the melting sub-peak temperature on one surface and the melting sub-peak temperature on the other surface.