| 摘要 |
<p>A process and an extruder cleaning composition for removing deposits of encrusted and decomposed material at elevated temperatures from the interior surfaces in contaminated zones of an extruder. The extruder cleaning composition comprises (1) discrete, crushable particles of a highly crystalline thermoplastic first polymer having a high brittle point and (2) a thermoplastic second polymer which has a melting point below said brittle point and which upon heating above its said melting point forms a fluid-phase carrier for said particles, said highly crystalline polymer having a melting point up to about 350 DEG C. One method of operating the process comprises charging the composition into the inlet of the barrel of an extruder while the extruder is operated at barrel temperatures which ahead of and in its contaminated zones are above the melting point of the second polymer and below the brittle temperature of the first polymer, melting the second polymer in the barrel ahead of said contaminated zones, crushing the first polymer in said contaminated zones and thereafter melting said crushed polymer in the barrel, and removing the composition from the outlet of the barrel in melted form along with loosened deposits occluded therein.</p> |
