| 摘要 |
Methods for cleaning screw extruder, especially powder-coating extruders, include filling the extruder barrel with a gel purge formulation comprised of a high-boiling pyrrolidone or piperidone (lactam) solvent (most preferably N-methyl pyrrolidone (NMP)), thickened with 5-50 wt.% of a thermoplastic resin thickening agent, most preferably polystyrene (PS). Once the extruder barrel is filled with the gel purge formulation, the screws are stopped and the gel allowed to soak for between about 10 to about 30 minutes. The screws are then restarted and the gel is discharged from the extruder. Immediately after the gel purge formulation exits the machine, a small amount of a thermoplastic "rinse" polymer (e.g., polyethylene) may be added so as to remove any vestigial amount of the gel purge formulation therefrom.
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