Patent attributes
The polyester composition giving formed articles, such as fibers or films, exhibiting improved color depth and clarity, when dyed, has characteristics comprising an intrinsic viscosity of not less than 0.60, a methyl terminal group concentration of less than 1.0 equivalent/ton, and a carboxyl group concentration of not more than 60 equivalents/ton, and contains 0.1 to 5 percent by weight of a metal-containing phosphorous compound produced by reacting a phosphate ester with an alkali metal and/or alkaline earth metal-containing compound in an amount of 0.5 to 3 parts by mole converted into the alkali metal per part by mole of said phosphate ester. Therein, the “amount converted into the alkali metal” is the double of the molar number of the alkaline earth metal, when the alkaline earth metal is used, or the sum of the double of the mole number of the alkaline earth metal and the mole number of the alkali metal, when the alkali metal and the alkaline earth metal are simultaneously used.
