The first polymeric tapes were launched in the pipeline industry in the mid 1950ies. Polymeric tapes have been used worldwide for the external corrosion prevention of buried pipelines since then.
From the beginning, mostly PE- or PVC carrier foils were coated on one side with an adhesive layer based on bitumen mastic, mastic or butyl-rubber in the tape manufacturing process.
One aspect that has received little attention so far is the effect how different tape production processes may have an impact on the quality and intrinsic material properties, especially the long-term expectancy of the tape coatings.
The most common tape production process is laminating an adhesive layer onto a PE-or PVC carrier foil. The majority of tape coatings-especially 2-ply tapes- are manufactured in this way.
By repeating the lamination process and adding an adhesive layer on top of the PE-carrier foil, a 3-ply tape structure can be achieved.
A more sophisticated and complex way to produce tapes is to manufacture them in a coextrusion process. The coextrusion process technology requires more than one polymer melt stream as each melt stream is produced by its own extruder. This process requires a lot of technical expertise. However, the effort is more than justifiable, since the product properties and, in particular, the long-term behavior are significantly increased and improved. Some of these are properties that cannot be seen from the outside of the products and can only be checked to a limited extent by short-term tests.
This presentation will give an insight to the different process technologies and their impact on the intrinsic material properties of the tape coatings, which are of special importance for the long term durability of the field joint coatings.