Method for closing a tray composed of natural fibres and/or starch with a sealable foil, tray closed in such a way and package unit formed therewith

摘要

The cover foil (3) is sealed to the edge of the dish (1) which is made mainly from natural particles, fibres or starch. The connecting strength between the foil and surface particles is greater than the connecting strength between the surface particles and the rest of the dish material. The cover foil comprises a lower melting material on the dish side than on the side remote from the dish. The pressure used when sealing is so great that the surface of the dish material undergoing sealing is smoothed out.