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US 5,393,863 AGranted
Production of branched polyesters
AssigneeEastman ChemicalI Company
InventorsCheuk C. Yau, Clinton Cherry
Life of this patent
Estimating the term…
Abstract
Disclosed is an improvement in a process for producing branched polyesters wherein a precursor polyester is first formed and subsequently the precursor polyester is formed into particles and further polymerized in the solid state, wherein the improvement comprises contacting the particles while at a temperature of about 140.degree. to about 2.degree. C. below the melting point of the polyester with the vapor of water or an organic compound having at least one OH group.
Claims14
A process for producing branched polyesters having improved resistance to gel formation comprising
- a) producing a precursor polyester having repeat units from at least 60 mol % terephthalic acid and at least 60 mol % ethylene glycol, and an I.V. of about 0.3 to about 1.0, b) forming the precursor polyester into particles, c) further polymerizing said particles in the solid state, and d) contacting said particles while at a temperature of about 140.degree. to about 2.degree. C. below the melting point of the polyester for a time of about 1 to about 100 hours with inert gas having a flow rate of greater than 2.times.10.sup.-2 meters per second, said inert gas containing about 300 to about 7000 parts per million by volume of the vapor of water or an organic compound having at least one OH group.
Dependencies are inferred from the claim text.