| abstract |
An improved clarity copolyester of a diethylene glycol modified poly(ethylene terephthalate) has a b* value of less than 15, preferably less than 10. The copolyester composition has an inherent viscosity of about 0.4 to 1.0 dL/g and comprises (A) 100 mol percent dicarboxylic acid residue component, (B) 100 mol percent diol residue component, (C) catalyst residues and (D) color control agent residues. The dicarboxylic acid residue component comprises at least 75 mol percent of terephthalic acid residues. The diol residue component comprises 10 to 50 mol percent diethylene glycol residue and 50 to 90 mol percent ethylene glycol residue. The catalyst residues comprise 20 to 100 ppm manganese, 50 to 300 ppm antimony, 0 to 100 ppm titanium and 40 to 150 ppm phosphorus, based on the weight of the copolyester. The color control agent residues comprise organic or inorganic toners present in a sufficient amount to reduce the b* color value of the combination of components A, B, and C to less than 15 by the addition of component D. Preferably, the color control agent residues comprises either (i) 40 to 100 ppm cobalt, (ii) 1.5 to 10 ppm of blue compounds of substituted 1,4-bis(2,6-dialylanilino) anthraquinones and 0.5 to 6 ppm of red compounds of anthraquinones and (iii) 0.5 to 10 ppm of 1-cyano-3H-dibenz[f,ij] isoquinoline-2,7-diones, all ppm based on the weight of the copolyester. |