Hello,

We produce rolled goods based upon TPU via crosshead extrusion with a single screw extruder (single stage, mixing element). When we combine a glossy TPU with a low gloss acrylate terpolymer, we get low gloss streaks in the product. The gloss streaks move around (not die lines) and they even appear if we pre-compound the two polymers before extruding into the final form.

Graduated, flat and inverse extruder temperature profiles have been tried with no effect.

Can this be caused by a dead spot in the die (material collects, and sloughs off)?

Thanks in advance.