METHODS FOR LOWERING MELT VISCOSITY AND IMPROVING HEAT-SEALABILITY OF POLYESTER AND FOR MANUFACTURING A HEAT-SEALED CONTAINER OR PACKAGE

• Main Authors: KUUSIPALO, JURKKA, NEVALAINEN, KIMMO, ROSLING, ARI, KYLLIÄINEN, OUTI, KHAJEHEIAN, MOHAMMAD, RÄSÄNEN, JARI, RIBU, VILLE, TOUMINEN, MIKKO, KOTKAMO, SAMI
• Format: Patent
• Language: English; French
• Published: 30.07.2015
• Subjects: ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F,C08G; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING; CHEMISTRY; COMPOSITIONS BASED THEREON; CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS,e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES,DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; CONVEYING; GENERAL PROCESSES OF COMPOUNDING; HANDLING THIN OR FILAMENTARY MATERIAL; LAYERED PRODUCTS; LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT ORNON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM; METALLURGY; ORGANIC MACROMOLECULAR COMPOUNDS; PACKAGES; PACKAGING ELEMENTS; PACKING; PERFORMING OPERATIONS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR; SHAPING OR JOINING OF PLASTICS; STORING; THEIR PREPARATION OR CHEMICAL WORKING-UP; TRANSPORTING; WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL; WORKING-UP

The invention relates to methods for lowering the melt viscosity and thereby improving heat-sealability of a polyester. The invention also relates to a method for manufacturing a heat-sealed container or package from fibrous- based, polyester-coated packaging material, and a method for heat-sealing polyester. The solution according to the invention is subjecting polyester to electron beam (EB) radiation. The lowered melt viscosity allows a lower heat- sealing temperature, and permits sealing of polyester to an uncoated fibrous surface. The preferred polyester for the invention is polylactide, as such or as blended with another polyester. L'invention concerne des procédés pour diminuer la viscosité à l'état fondu et améliorer ainsi la thermoscellabilité d'un polyester. L'invention concerne en outre un procédé pour fabriquer un récipient ou un emballage thermoscellé à partir d'un matériau d'emballage à base fibreuse, revêtu de polyester, et un procédé pour thermosceller du polyester. La solution selon l'invention soumet du polyester à un rayonnement de faisceau d'électrons (EB). La viscosité à l'état fondu diminuée permet d'utiliser une température de thermoscellage plus basse, et permet de sceller du polyester sur une surface fibreuse nue. Le polyester préféré pour l'invention est le polylactide, tel quel ou en mélange avec un autre polyester.