Screw designs having improved performance with low melting PET resins

US8057726B2 · kind B2 · utility

Assignee

• GRUPO PETROTEMEX, S.A. DE C.V. · MX

Inventors

• Marcus David Shelby · Church Hill, US
• Michael Eugene Donelson · Kingsport, US
• Frederick Leslie Colhoun · Kingsport, US
• Steven Lee Stafford · Jonesborough, US
• Mark Edward Stewart · Kingsport, US
• Stephen Weinhold · Kingsport, US
• Edward Lewis Boochard · Kingsport, US
• Robert Noah Estep · Kingsport, US

Key dates

• Filing date: May 26, 2009
• Grant date: Nov 15, 2011
• Expiry date: Mar 27, 2030

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B29K2105/256
• WIPO field: Other special machines
• WIPO sector: Mechanical engineering

Abstract

Disclosed is a process for a melt processing a polyethylene terephthalate resin characterized by one or more of the following. The polyester particles may have at least two melting peaks wherein one of the at least two melting peaks is a low peak melting point with a range from 140° C. to 220° C., or from 140° C. to 230° C., and having a melting endothermic area of at least the absolute value of 1 J/g. The polyester particles may have one or more melting peaks at least one of which when measured on a DSC first heating scan has a heating curve departing from a baseline in the endothermic direction at a temperature of less than or equal to 200° C. The polyester particles may have an It.V. at their surface which is less than 0.25 dL/g higher than the It.V. at their center. The polyester particles may have not been solid stated. The melt processing device comprises a screw with a total length, L, a feed zone length in the range from 0.16L and 0.45L, a taper angle, φ, in the range from 0.5 degrees and 5.0 degrees and a compression ratio, CR, in the range from 2.0 and 5.0.