Window film base stock, the product can be used as the base film raw material of auto window film. The PET window film base stock can block ultraviolet rays, block heat, and have anti-glare and explosion-proof functions. The building window membrane has the functions of heat insulation, energy conservation and indoor temperature regulation; Effectively block harmful ultraviolet rays and prevent furniture from fading; Block solar glare, prevent light pollution and protect vision; It has multiple functions such as safety, explosion protection, high temperature and fire resistance.