Process for producing polymer films from aqueous polymer compositions

• Main Authors: LAWRENCE JOSEPH SCHNIEDERS, JOSEPH ARTHUR LAROSE, ERIC ALAN OVERHOLT
• Format: Patent
• Language: English
• Published: 20.10.1998
• 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

The present invention relates to a process for producing a polymer film from an aqueous polymer composition wherein the process comprises the steps of: (A) introducing an aqueous composition comprising water and a polymer through at least one feed unit in one or more upstream sections of an extruder comprising a plurality of interconnecting sections wherein at least one downstream section comprises a homogenizer mixer; (B) conveying the composition through the extruder; (C) maintaining the composition at a temperature of from about 60 DEG C. to about 160 DEG C. as it is conveyed through the extruder; (D) reducing the pressure in at least one section of the extruder downstream of the feed units sufficiently to evaporate at least a portion of the water in the composition conveyed through that section; (E) removing the evaporated water from the extruder through at least one vent in a downstream section to form a water-reduced composition; and (F) extruding the water-reduced composition through a die thereby to produce a film. In other embodiments, the invention relates to a process for producing sheets of a pressure-sensitive adhesive composition and to a process for coating a composition such as a pressure-sensitive adhesive composition onto a support web. In each of the embodiments of the invention, a film, sheet or coating composition is formed from an aqueous composition containing large amounts of water, and the product obtained is essentially water-free.