Injection Molding Polyethylene Terephthalate (PET)
“An apparatus for producing injection-molded parts, in particular PET preforms, typically includes an extruder for processing and/or plasticizing material that is normally present in granular form. A transfer reservoir receives processed and/or plasticized material, and a piston unit is provided for further processing the material. Normally, the production of PET preforms using an injection molding process involves the application of a single screw extruder for plasticizing materials, such as plastic pellets. For subsequent processing, the plasticized material is injection-molded with a piston unit--shot pot--or directly injected with an axially movable screw. Because PET is hygroscopic and because moisture causes a hydrolytic decomposition of polymer chains, the material is pre-dried in a most complex process, in particular when material in granular form is involved.”
Recent US Patents
10/19/2010
7,815,833
Method for producing injection-molded parts
Fischbach et al of KraussMaffei Technologies, Germany processing PET material by means of a twin-screw extruder with several processing zones. At least two processing zones are implemented as degassing zones. The processed and/or plasticized material is transferred to a transfer reservoir and then further processed by a piston unit. (RDC 1/24/2011)