PRODUCTION METHOD OF PLASTIC PIPE IN LAYERS

摘要

The object of the invention is a method to produce plastic pipe where a pipe of two or more layers is extruded and where at least one layer has additive that by heat treatment releases free radicals. Immediately after the extrusion, the pipe is heat treated by leading it either through a hot salt bath or an infra-red radiation so that the mentioned additive decomposes. Now, the layer(s) having additive get cross-linked and additionally the crosslinked layer(s) fix with chemical bonds to at least one other layer.;With this method it is possible to produce a plastic pipe where there is no need to use a separate adhesion plastic layer to fix to each other layers that reject each other.

主权项

1. Production method for a plastic pipe consisting of at least two layers and according to this method:
the plastic pipe is produced by an extruder; at least the innermost layer (1) is cross-linked; in the before mentioned cross-linking, at least one additive is used that forms free radicals when it decomposes by the effect of the heat and causes thus that the chemical bonds are formed; the heat treatment needed for the cross-linking is done by infra-red radiation obtained by infra-red lamps or salt bath or by some other convenient method; plastic material layer is installed to the plastic pipe to hinder or prevent the oxygen to go through the wall of the pipe, characterized in that alongside at least the innermost layer (1), a plastic material layer (2) is made that decreases or prevents the oxygen flow through the pipe wall; by using the before mentioned heat treatment, the chemical bonds are also obtained in addition to layer's/layers' inside cross-links, the chemical bonds are also obtained between the cross-linked layer and next to it being layer (2) that decreases or prevents the oxygen flow through the wall; all the cross-links of the plastic pipe are achieved through one heat treatment.