Coextrusion Feedblocks, 1993 International European Extrusion Coating Symposium Proceedings
Hassan Helmy
Coextrusion is extensively used in the manufacture of multilayer sheet and film for use in industrial and packaging applications. Coextruded structures vary from the simple 2 layer structure to 5, 6 and 7 layers used in barrier food applications.
In a coextrusion line, the coextrusion block or the black box is the heart of the system. This is particularly so in the case of a complex multilayer coextrusion application where sheet appearance and individual layer uniformity are very critical to the performance of the end product.
The design interaction between the coextrusion block and the die is also very important as it can equally impact layer uniformity.
A good block/die design should be able to achieve layer distribution in the range of l-2% of the total structure thickness.
Coextrusion Feedblocks, 1993 International European Extrusion Coating Symposium Proceedings