Patent ID: 7459217

Claim:
A flame-retardant polyester film comprising resin layers laminated on both surfaces of a polyester film, wherein each of the resin layers satisfies the following Formula (1) and has non-flammable gas generating rate of 3 to 40 percent over the range of 180° C. to 450° C.: 15≦( Wc 1 −Wc 2 )/ Wc 0 ×100≦99 (1) where Wc 0 represents the weight of the resin layer at 25° C. in air, Wc 1 represents the weight of the resin layer after the temperature thereof is raised from 25° C. to 600° C. in air, and Wc 2 represents the weight of each of the resin layers after the temperature thereof is raised from 25° C. to 800° C. in air; and each of the resin layers comprises polyimide and 30 to 65 percent by weight aluminum hydroxide based on weight of the resin layer; and wherein 70 to 100 percent of the total structural units of the polyimide are structural units represented by the following Formula (III); in Formula (III), R′ represents at least one group selected from groups represented by the following Formula (IV); in Formula (IV), Y represents at least one group selected from the groups represented by the following Formula (V); —O—, —CH 2 —, —CO—, —SO 2 —, —S—, —C(CH 3 ) 2 — (V).