Process for the manufacture of polyester film

• Main Authors: ALBERT; ANTHONY P, FEIL; JOSEPH N
• Format: Patent
• Language: English
• Published: 31.07.1984
• Subjects: AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F,C08G; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING; CHEMISTRY; COMPOSITIONS BASED THEREON; GENERAL PROCESSES OF COMPOUNDING; METALLURGY; ORGANIC MACROMOLECULAR COMPOUNDS; PERFORMING OPERATIONS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR; SHAPING OR JOINING OF PLASTICS; THEIR PREPARATION OR CHEMICAL WORKING-UP; TRANSPORTING; WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL; WORKING-UP

The invention contemplates the manufacture of a wrinkle-free, amorphous, unoriented polyester film which is produced by an extrusion blowing process. The process consists of extruding a bubble of polyester, expanding the bubble, and then collapsing the bubble at a temperature above the polyester's glass transition temperature to prevent the formation of wrinkles. The collapsing step is effected through the use of a shroud which receives the bubble and has a low friction surface.