Processes and compositions for cleaning mixing devices to improve polymer production

摘要

Processes and compositions for cleaning mixing devices are disclosed that improve the production and quality of thermoplastic polymer resins subsequently produced in the mixing device, while reducing the time needed for cleaning and/or change over. A cleaning mixture comprising polymeric resin pellets having a Rockwell R hardness of 85 to 140 externally coated with an aqueous solution containing sulfonate salts, alkyl aryl sulfonate salts, alkyl sulfate salts, C6 to C36 carboxylic acid salts, or mixtures thereof, is used to purge the mixing device. The surfactant salt is present in the aqueous solution at 0.2 to 30 wt % of the solution, the aqueous solution having a pH of 6.0 to 9.0.

主权项

1. A process to clean melt processing equipment used to compound, mold, and/or extrude resins containing a polymer, comprising:
purging the melt processing equipment with a cleaning mixture (purge) comprising:
from 70 to 99 wt % of thermoplastic polymeric resin pellets, the pellets having a Rockwell R hardness of from 85 to 140 as measured by ASTM D785; andfrom 1 to 30 wt % of an aqueous solution that contains 0.2 to 30 wt % of a surfactant salt selected from at least one of the following: sulfonate salts, alkyl aryl sulfonate salts, alkyl sulfate salts, C6 to C36 carboxylic acid salts, and mixtures thereof, wherein the aqueous solution has a pH of 6.0 to 9.0; and running the melt processing equipment at a temperature of from 200 to 380° C. to obtain a purged resin while cleaning the melt processing equipment.