Method for welding multilayer composites with barrier layers

Abstract

The invention relates to a welding method of material webs, each of which consists of a multilayer composite with a barrier layer and which are connected to each other via a sealing seam. In order to provide a welding method by means of which a sealing seam can be produced which on the one hand meets the highest demands on strength and on the other hand prevents the penetration of light, in particular ultraviolet light, into the product to be packaged, according to the present invention The invention creates a sealing seam by bringing together two sealing surfaces of two tools, wherein a material web is arranged between the sealing surfaces and the resulting sealing seam has two seams located adjacent to each other seam, i.e. a primary seam and a secondary seam, and, during the production of the primary seam, the two sealing surfaces exert the primary welding pressure on the material web, and, during the production of the secondary seam, the two sealing surfaces A secondary welding pressure is applied to the material web, wherein the secondary welding pressure is lower than the primary welding pressure at least in some sections, and in the secondary processing step at least one of the two sealing surfaces is structured.

Description

technical field [0001] The invention relates to a method for producing a sealing seam connecting two material webs of a multilayer composite with a barrier layer, wherein the two material webs are positioned between a first tool and a second tool between sealing surfaces. Background technique [0002] To produce a sealed seam, welding tools are used, for example. In that case, the sealing seam is a connecting seam between two material webs. Sealing means joining the material web surfaces. Usually, this is achieved through the action of high temperature. Sealing seams are especially used in the production and closure of bags and sacks, and in the packaging industry for the application of cover films to cans or trays. [0003] The welding tool has a sealing surface of width b. In order to produce a sealed seam, the sealing surface is pressed, optionally under pressure, onto the material web to be treated. Usually there is a corresponding counter tool in order to clamp th...

AI Technical Summary

Problems solved by technology

[0008] However, the use of a contoured sealing surface and often increased pressure leads to damage to the barrier, so that, in practice, a small amount of UV light can penetrate into the bag, although a strong connection has occurred between the material webs, This may adversely affect the quality of the packaged product

[0009] This can only be prevented if the pressure on the material webs is reduced, however this may lead to a connection between the material webs that does not meet the strength requirements, especially if there are product residues between the material webs

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