Device for the successive introduction of additives into a polymer granulate and use of the device

A method of using a device for sequentially introducing additives in a polymer granulate, comprising:

• introducing the additives into the device comprising:
• a mixer with housing, and at least one mixer shaft;
• at least one first inlet opening for a polymer granulate,
• at least one second inlet opening for one first additive, situated in transport direction below the first inlet opening for the polymer granulate,
• at least one first outlet opening for the polymer granulate mixed with the first additive, situated in transport direction below the first inlet opening for the polymer granulate and from the second inlet opening for the first additive, consequently forming a first mixing zone,
• at least one third inlet opening for a second additive, situated in transport direction below the first inlet opening for the polymer granulate, the second inlet opening for the first additive and the first outlet opening for the polymer granulate mixed with the first additive,
• at least one second outlet opening for the polymer granulate, mixed with the second additive, situated in transport direction below the first inlet opening for the polymer granulate, the second inlet opening for the first additive, the first outlet opening for the polymer granulate mixed with the first additive and the third inlet opening for the second additive, thereby forming a second mixing zone,
• driving units for driving the at least one mixing shaft,
• wherein
• non-continuous conveying pattern shapes are helically mounted within the first mixing zone on the surface of the mixing shaft, effecting a transport and mixing of the polymer granulate,
• a section being provided, including a continuous screw conveyor (5c) between the first outlet opening for the polymer granulate mixed with the first additive and the third inlet opening for the second additive between the mixing zones on the surface of the mixing shaft, the section not being permeable for returning solids from the following mixing zone, and
• helically arranged non-continuous conveying pattern shapes mounted in the following mixing zone then again on the surface of the mixing shaft, effecting a transport and mixing of the polymer granulate, wherein the device is used for mixing a polymer granulate with two different additives.