| 摘要 |
A four-ply co-extruded foil with an intermediate ply made of thermally decomposable material is produced in a device having five extruders. The extruder that produces the intermediate ply of thermally decomposable material and an adjacent extruder are designed to process thermally decomposable materials. During a first stage, the outer ply (A) is produced by extruder (Ea) and at the same time the outer ply (B) is produced by extruder (Eb) and associated extruder (E3). The extruders (Eb, E3) are fed with the material which forms the outer ply (B) and the plies produced by extruders (Eb; E3) have together the thickness of the outer ply (B). These two plies are joined by fusion into a single ply while the intermediate layers (Z1, Z2) are produced by extruders (E1, E2). In a second stage, the outer ply (A) is produced by associated extruders (Ea, E1), the outer ply (B) is produced by extruder (Eb) and the intermediate plies (Z1, Z2) are produced by extruders (E2, E3). |
