Method for producing a multilayer preform and preform produced according to the method

• Main Authors: SCHOEPF, KARL, DIENER, NORBERT, SCHMIDT, WOJCIECH
• Format: Patent
• Language: English; French; German
• Published: 30.12.1998
• Edition: 6
• Subjects: AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING; 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

Zum Herstellen eines mehrschichtigen und eine innere Sperrschicht (13a) aufweisenden Vorformlings (14) mittels einer Spritzgussvorrichtung (1) werden begrenzte Mengen aus einem ersten (10) und einem zweiten (11) Bestand gespritzt. Der zweite Bestand besteht aus einem Sperrschichtmaterial (13). In einer Vorphase wird Material (12) aus dem ersten Bestand (10) in den Formhohlraum (5) bis zu einer Teilfüllung gespritzt, und in einer Hauptphase wird parallel und koaxial eine begrenzte Menge aus dem ersten Bestand (10) und aus einem zweiten Bestand (11) in den Hohlraum (5) eingespritzt. A new procedure manufactures multilayer preforms. These have an internal barrier layer (13a). The equipment includes a concentric, selectively-plugged injection nozzle (2), mould (3) and core (4) forming a cavity (5). Two quantities of thermoplastic are prepared, to form the outer, sandwiching layers (12a, b) and the inner barrier layer (13). Limited quantities of each are injected. In the novel procedure, during the preliminary phase, a partial filling of the first plastic (12) is injected into the cavity. In a main phase, both components are injected together. Their boundaries are maintained both coaxial and parallel. Also claimed is the preform. Its body section is a tri-layer including the sandwiched barrier layer (13a) completely surrounded (including at its edges) by another material.