Patent ID: 11965073
Assignee: DUPONT TEIJIN FILMS U.S. LIMITED PARTNERSHIP
Field: Other special machines (Mechanical engineering)
Classification: CPC C | IPC C

Claim 0:
1. A polyester film comprising a polymeric phosphonate flame retardant in an amount of from 1 wt % to 25 wt %, by total weight of the film, and further comprising at least one metal cation selected from the group consisting of Group I and Group II metal cations, wherein said metal cations are present in the form of a salt with a counter-anion selected from hydroxide, polyacrylate, hydrogen carbonate, carboxylate, chloride, acetate, formate and nitrate, wherein said polyester is polyethylene terephthalate, wherein the amount of said at least one metal cation is greater than 0 ppm and not more than 500 ppm relative to the amount of polyester, and wherein said phosphonate flame retardant is a phosphonate flame retardant of formula I:, wherein:
Ar is an aromatic group and —O—Ar—O— is derived from a compound having one or more, optionally substituted, aryl rings;
X is a C1-20 alkyl, C2-20 alkene, C2-20 alkene, C5-20 cycloalkyl or C6-20 aryl; and
n is an integer from 1 to 100.