| 主权项 |
1. A copolyester composition comprising a biodegradable aliphatic-aromatic copolyester that comprises:
(a) a dihydric alcohol group selected from an ethylene glycol group, 1,2-propylene glycol group, 1,3-propylene glycol group, 1,2-butanediol group, 2,3-butanediol group, 1,4-butanediol group, tetramethyl cyclobutanediol, isosorbide groups, 1,3-cyclohexanedimethanol groups, 1,4-cyclohexanedimethanol groups, hexylene glycol groups, bio-derived diol groups, and combinations thereof; (b) an aromatic dicarboxylic acid group derived from a depolymerized aromatic polyester component selected from poly(ethylene terephthalate), poly(butylene terephthalate), poly(trimethylene terephthalate), and combinations thereof; and (c) an adipic acid group; wherein the composition further comprises (d) a titanium-containing catalyst; (e) an aromatic polyester residue selected from an isophthalic acid group, antimony-containing compounds, germanium-containing compounds, cobalt-containing compounds, tin, tin-containing compounds, titanium, aluminum, aluminum salts, alkaline salts, alkaline earth metal salts, phosphorous-containing compounds, sulfur-containing compounds, naphthalene dicarboxylic acid groups, epoxies, and combinations thereof; and (f) a color reducing compound selected from C5-12 compounds having at least three —OH groups and combinations thereof; wherein the aliphatic-aromatic copolyester has a number average molecular weight of at least 20,000 Daltons and a polydispersity index from 2 to less than 6; wherein the copolyester composition is made by a process comprising adding the color reducing compound to the copolyester melt to obtain a whiteness of at least L*=70.0; a*=−8.0; b*=15.0 as determined using a colorimeter with D65 illumination; and wherein polycarbonate is absent from the copolyester composition. |
