PROCESS FOR LAMINAR POLLYMER EXTRUSION

• Main Authors: ARGHYRIS; LAURENT, KAMAL; MUSA R, LOHFINK; GUNTER, HOZHABR-GHELICHI; SASSAN
• Format: Patent
• Language: English
• Published: 23.02.1993
• Subjects: AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING; LAYERED PRODUCTS; LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT ORNON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM; PERFORMING OPERATIONS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR; SHAPING OR JOINING OF PLASTICS; TRANSPORTING; WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL

In a laminar extrusion, overlapping layers of an EVOH phase are dispersed into a PP or MAPP matrix phase incompatible with the EVOH phase to form a vapor, gas and/or organic liquids barrier. When the matrix phase is a PP phase, MAPP can be added to improve adhesion between the overlapping layers and the matrix phase. MEPR and/or PE can also be mixed with the EVOH and/or PP phase to adjust the mechanical properties of the extrusion. In order to produce the extrusion, a molten polymer blend including bodies of the EVOH phase dispersed in the PP or MAPP phase is first prepared and then extruded through a die unit. In the die unit, a converging extensional flow is produced to lengthen the dispersed bodies of EVOH phase in a first direction while a diverging extensional flow lengthens these bodies in a second direction transversal to the first one. Such lengthening of the bodies produces in the extrusion the overlapping layers of EVOH phase.