B - Operations – Transporting – 29 – B
Patent
B - Operations, Transporting
29
B
402/211, 18/509
B29B 9/16 (2006.01) C08G 63/78 (2006.01) C08G 63/90 (2006.01)
Patent
CA 1128694
ABSTRACT OF THE DISCLOSURE There is disclosed a process for reducing the acetal- dehyde content and the generation rate of acetaldehyde of poly- ethylene terephthalate chip which has a crystallinity of at least about 30% in order to render the polyethylene terephthalate suitable for making containers which are useful in the carbonated beverage industry. This process comprises stabilizing the poly- ethylene terephthalate by heating it at an elevated temperature in air and maintaining an air to chip ratio at a predetermined value of at least about 0.8 standard cubic foot of air per minute/pound of resin per hour and at a vapor velocity of at least about 0.5 foot per second. The air used in the stabiliza- tion process has a dew point of less than about -30 C. The stabilized polyethylene terephthalate produced by this process has an acetaldehyde level of less than about 2.5 parts per mil- lion, a generation rate of acetaldehyde of less than about 3.0 parts per mullion per minute and an intrinsic viscosity of from about 0.60 to about 0.95 deciliters per gram. There is also disclosed a process for molding a polyethylene terephthalate preform comprising melting the above described polymer, forming it into the desired preform shape, and cooling the molten poly- mer. This preform may then be reheated above its glass transition temperature and molded into the desired container shape.
327767
Freed William T.
Halek George W.
Pauls Stanley L.
Rupp Raymond W.
Schaul Jerome S.
Celanese Corporation
Smart & Biggar
LandOfFree
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