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US 12,692,345 B2Granted
Method for preparing a copolyester
AssigneeHanwha Solutions Corporation
InventorsEung Gyu Kim, Ho Seong Nam, Kyoung Won Yim, Ju Mi Yun
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Abstract
The present disclosure relates to a method for preparing a copolyester. More specifically, the present disclosure relates to a method for preparing a copolyester that reduces the use of a cobalt-based coloring agent but minimizes yellowing, by using a specific thermal stabilizer.
Claims12
A method for preparing a copolyester comprising steps of:
- conducting an esterification reaction of terephthalic acid, ethyleneglycol, and 1,4-cyclohexanedimethanol (CHDM), in the presence of a titanium-based catalyst;
- and
- conducting condensation polymerization of the reaction product of the esterification reaction, in the presence of a phosphorus-based thermal stabilizer,
- wherein the phosphorus-based thermal stabilizer is calcium bis[monoethyl(3,5-di-tert-butyl-4-hydroxylbenzyl)phosphonate] or triethyl phosphonoacetate,
- wherein, when using calcium bis[monoethyl(3,5-di-tert-butyl-4-hydroxylbenzyl)phosphonate] as the phosphorous-based thermal stabilizer, the phosphorous-based thermal stabilizer is added in an amount such that a content of phosphorous element is 300 ppm or more and 1,000 ppm or less, based on a weight of a finally produced copolyester, and
- wherein, when using triethyl phosphonoacetate as the phosphorous-based thermal stabilizer, the phosphorous-based thermal stabilizer is added in an amount such that a content of phosphorous element is 5 ppm or more and 20 ppm or less, based on the weight of the finally produced polyester.
3 more elements
Dependencies are inferred from the claim text.