What type extruder and processing conditions should be used to blow mold Eastar™ copolyester 6763?
The same extruder design is suggested for extrusion blow molding Eastar™ copolyester 6763 as is used for PVC resins. Eastar™ copolyester 6763 is a relatively viscous polymer and requires a low-work screw to prevent melt temperature override. Best results are obtained when using a low-shear, barrier screw designed for this material. Most extrusion blow molding machines are equipped with a copper coil for cooling the barrel. Circulating air through the coil generally provides adequate cooling, although oil is the most commonly used medium. Oil supplied at a temperature of approximately 120 degrees C (250 degrees F) is suggested for cooling. Barrel cooling can be employed on the front zones, if necessary, to prevent melt temperature override. The melt temperature should be in the 215-225 degrees C (415-440 degrees F) range. Temperatures on the low side of the range provide better melt strength while temperatures on the high side provide a better surface finish. The 2 rear zone temperature
