Extrusion 

In the extrusion process the TPE pellets are poured into a hopper are heated in the barrel and turned into a melt by this heat and shear. A screw carries the melted plastic through a shaped die to produce continuous lengths of shapes with the same profile, which are then cooled by air or water.

Dryflex and Mediprene compounds are easily extruded into single and complex profiles. They can also be co-extruded with other materials to yield a part with both rigid and soft components. They exhibit improved profile flexibility.

The SEBS compounds, with their saturated intermediate blocks, are very stable against thermal degradation. On the other hand, the SBS compounds degrade if overheated or if a screw with excessively high compression ratio is used.

SEBS based materials

Equipment:	Extruders used for polyolefines are best for TPE compounds.
Length/diameter (L/D) ratio:	Min. 20:1
Compression ratio:	Min. 3.5:1
Melt temperature:	Normally 150 - 210°C, although temperatures up to 260°C are permissible.
Temperature profile:	Feed Zone to Die 170, 180, 190, 200 and 210°C is suitable, can be adjusted to suit grade and screw. (Lower temperature for the softer compounds.)
Screw design:	Best extruded using screws that have a high compression ratio (3:1) and long, fairly shallow feed zones. Screws with compression ratio of 3.0 - 4.5 are normally preferable. The softer compounds generally give a lower output at increased backpressure.

SBS based materials

Equipment:	SBS based compounds can be extruded on virtually all types of extruders for thermoplastics. Since SBS compounds display less swelling than polyolefines, the length of the form giving part of the die is less critical.
Length/diameter (L/D) ratio:	Min. 20:1
Compression ratio:	Min 2.5:1
Melt temperature:	150 - 205°C, should not exceed 205°C
Temperature profile:	150°C at infeed zone to 205°C at the die, gives highest output.
Screw design:	Compression ratio should be low, the melt sections should be fairly deeply threaded and the L/D ratio should be >20:1

Comprehensive details about our range of extrusion grades, and processing guides are available in PDF format;

Dryflex Extrusion Grades

Processing Guide

Problem Solving