Methods for producing improved stable polyethylene terephthalate
AssigneeOwens-Illinois, Inc.
InventorSaleh A. Jabarin
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Abstract
Methods for producing improved, thermally-stable polyethylene terephthalate resins are provided. Polyethylene terephthalate resins are provided that can be fabricated into products such as carbonated beverage containers with a minimum of degradation products such as acetaldehyde preferably by rapidly polymerizing a prepolymer from an i.v. of about 0.2 to an i.v. of at least about 0.7.
Claims28
A method of producing an improved, stable, polyethylene terephthalate resin from a low-molecular weight prepolymer of ethylene glycol and terephthalic acid having an intrinsic viscosity of about 0.1 to 0.3, the method comprising the steps of:
- (A) Further polymerizing the prepolymer to a higher intrinsic viscosity of about 0.4 to 0.6 at a temperature of about 270.degree. C. to 290.degree. C. at a high reaction rate for less than about one-half hour;
- and (B) Further polymerizing the reaction product of Step (A) in a solid state to provide a stable resin with an intrinsic viscosity of at least about 0.7.
A method of providing an improved thermally stable polyethylene terephthalate prepolymer of ethylene glycol and terephthalic acid from a relatively low-molecular weight resin having an intrinsic viscosity of about 0.1 to 0.3, the method comprising the steps of:
- (A) Further polymerizing the prepolymer in a liquid state from a lower intrinsic viscosity to an intrinsic viscosity of at least 0.7 at a temperature of about 270.degree. C. to 290.degree. C. at a higher reaction rate for less than about one-half hour to provide a thermally-stable polyethylene terephthalate resin.
A method of producing an improved, stable,polyethylene terephthalate resin from a low-molecular weight prepolymer of ethylene glycol and terephthalic acid having an intrinsic viscosity of about 0.2, the method comprising the steps of (A) Further polymerizing the prepolymer at about 270.degree. C. to 290.degree. C. for a time greater than about one hour and less than about three hours to provide a product having an intrinsic viscosity of about 0.4 to 0.5, and (B) Further polymerizing the product of Step (A) in a solid state at about 200.degree. C. to 240.degree. C. to provide a stable resin having an intrinsic viscosity of at least about 0.7.
Dependencies are inferred from the claim text.