METHOD FOR PRODUCING A CLOSURE WITH THREAD AND A SEALING ELEMENT, AND POLYMER COMPOSITION FOR THE SEALING ELEMENT

摘要

The invention relates to a polymer composition of a sealing insert for a closure with thread for containers used, in particular, for fat-containing filling materials, and to a method for manufacturing such closure. The polymer composition is PVC-free and comprises two different polymers, one of which is a copolymer which includes polyethylene units and alkylene monomer selected from propylene, butylene, hexene and octene, and the other is a random copolymer that is a linear or branched interpolymer of ethylene and at least one C₃-C₂₀ alpha-olefin, wherein the polymer composition has Shore A hardness in the range of 45 to 90 and, in accordance with a test ASTM D395-97, method B, shows a compression set of 30-70% at 70°C. The invention provides a PVC-free sealing insert for containers with large-diameter openings with a low degree of migration of chemical substances.