Oxygen scavenging polyester blends having improved aesthetic characteristics

1. A preform having a preform wall comprising a composition comprising:

at least one polyester component

a transition metal catalyst, and

a vegetable oil comprising at least one molecule having a double allylic structure,

wherein the at least one polyester component comprises at least one acid unit and at least one diol unit, the concentration of the double allylic structures of the vegetable oil in the composition is greater than 5.0 meq/kg of all of the polyester components, and the preform has an ω value of less than 260 in an equation

ω

=

(

1

L

*

×

t

)

×

1000

where L* is a Hunter L* measurement in the range of between 0 and 100 excluding 0 and t is the thickness of the preform wall in mm.

2. The preform of claim 1 , wherein the at least one polyester component is a copolyester containing a metal sulfonate salt group.

3. The preform of claim 2 , wherein the metal sulfonate salt group is a metal sulfoisophthalate derived from a metal salt of 5-sulfoisophthalic acid, its dimethyl ester or its glycol ester.

4. The preform of claim 3 , wherein the metal salt of 5-sulfoisophthalic acid, its dimethyl ester or its glycol ester comprises a metal ion selected from the group consisting of Na + , Li + , K + , Zn 2+ , Mn 2+ , Co 2+ and Ca 2+ .

5. The preform of claim 2 , wherein the metal sulfonate salt group is in a range selected from the group consisting of 0.01 to 10.0 mole percent, 0.01 to 2.0 mole percent, 0.05 to 1.1 mole percent, 0.10 to 0.74 mole percent and 0.10 to 0.6 mole percent based upon the total moles of acid units in all of the polyester components.

6. The preform of claim 1 , wherein the transition metal catalyst is a compound containing at least one cobalt atom in a positive oxidation state.

7. The preform of claim 1 , wherein the transition metal catalyst is a salt containing at least one cobalt atom in a positive oxidation state.

8. The preform of claim 1 , wherein the transition metal catalyst is added to the composition at a level in a range selected from the group of between 10 and 600 ppm, between 20 and 400 ppm and between 40 and 200 ppm of metal relative to the total amount of the polyester components and vegetable oil present in the composition.

9. The preform of claim 1 , wherein the vegetable oil is selected from the group consisting of flax seed oil, linseed oil, evening primrose oil, borage oil, sunflower oil, soybean oil, grapeseed oil, corn oil, cotton seed oil, rice bran oil, canola oil and peanut oil.

10. The preform of claim 1 , wherein the concentration of the double allylic structures of the vegetable oil in the composition is greater than 7.0 meq/kg of all of the polyester components.

11. The preform of claim 1 , wherein the concentration of the double allylic structures of the vegetable oil in the composition is greater than 9.0 meq/kg of all of the polyester components.

12. The preform of claim 1 , wherein the concentration of the double allylic structures of the vegetable oil in the composition is greater than 14.0 meq/kg of all of the polyester components.

13. The preform of claim 1 , wherein the composition further comprises a polyamide.

14. The preform of claim 13 , wherein the polyamide is poly-metaxylylene adipamide.

15. The preform of claim 13 , wherein the polyamide is present in the composition at a level in a range selected from the group consisting of between 0.1 and 0.9% by weight of the total composition, 0.1 to 0.8% by weight of the total composition, 0.1 to 0.7% by weight of the total composition and 0.1 to 0.6% by weight of the total composition.

16. The preform of claim 1 , having an ω value of less than 93.

17. The preform of claim 1 , having an ω value of less than 24.

18. The preform of claim 1 , having an ω value of less than 20.

19. The preform of claim 1 , having an ω value of less than 15.

20. A biaxially oriented container manufactured from the preform of claim 1 .