Method for making all-plastic heat-sealable container

摘要

The invention provides a dynamic system for heat-sealing an all-plastic material in a continuous process at high speed. The invention includes an all-plastic heat-sealable container material comprising a multiple-layer composite, in sheet form, including a core layer and at least one outer layer on one side thereof. The layers preferably comprise thermoplastic material, the core layer material having a higher softening point than the outer layer material. The composite sheet is conveyed through a converting, side-seaming or other apparatus at high speed, the system being tuned to dynamically heat the outer layers to a molten state for heat sealing, while the core does not soften but remains undistorted. The core is thus thermally insensitive to heat at speeds used in side-seaming the composite, and as such it supports and maintains the structure of the sealing outer layers on its exterior while they are in a molten condition.