초록 ▼

The invention provides a process of manufacturing a shaped polyester article having an oxygen permeability of from about 0.2 to about 4.9 cc-mil/100 in2-24 hr-atm at a temperature of 23°C. and at 100% relative humidity inside and 60% relative humidity outside, and an enthalpy of recrystallization of

The invention provides a process of manufacturing a shaped polyester article having an oxygen permeability of from about 0.2 to about 4.9 cc-mil/100 in2-24 hr-atm at a temperature of 23°C. and at 100% relative humidity inside and 60% relative humidity outside, and an enthalpy of recrystallization of from about 0 to about -2.1 cal/g, as well as a linear dimensional shrinkage between about 0% and 6% when heated from about -60°C. to about 200°C. The crystalline polyester articles are useful as containers for microwavable, ovenable and/or frozen foods, and have good gas barrier properties, and post-mold dimensional stability from about -60°C. to about 200°C.

대표청구항 ▼

A process for producing a shaped polyester article comprising the steps: (a) heating a composition consisting essentially of a substantially non-oriented crystallizable thermoplastic polyethylene terephthalate homopolymer to a completely or substantially completely amorphous state; (b) maintaining t

A process for producing a shaped polyester article comprising the steps: (a) heating a composition consisting essentially of a substantially non-oriented crystallizable thermoplastic polyethylene terephthalate homopolymer to a completely or substantially completely amorphous state; (b) maintaining the composition heated in step (a) at a temperature above the peak crystallization rate temperature of said crystallizable polyethylene terephthalate homopolymer, while simultaneously contacting said composition with a surface which imparts shape to said composition, said surface being at or above the peak crystallization rate temperature from melt for said polyethylene terephthalate homopolymer; (c) maintaining the contact between said composition and said surface, at the surface temperature set forth in step (b), for about 20 seconds to about 5 minutes to provide a crystalline composition having an enthalpy of recrystallization of about 0 to about -2.1 calories per gram as measured by differential scanning calorimetry; (d) cooling the crystalline composition provided by step (c) at a rate of from between about 5°C. to about 80°C. per minute, for a time sufficient to provide a shaped article comprising said polyethylene terephthalate homopolymer, with said shaped article having an oxygen permeability of from about 0.2 to about 4.9 cc-mil/100 in2-24 hrs-atm at 23°C. and at 100% relative humidity inside and 60% relative humidity outside.