Cast Film Extrusion- Laboratory and Full Scale Production

摘要

Every commercial operator realizes that there will be start-up problems in a new process that hasrnonly been tried in the laboratory or in another manufacturing process. Melt temperature, shearrnand residence time will very likely all be different. The question is really how the product isrngoing to be different and how to eliminate the problem. In one case the film product producedrnworked perfectly in the laboratory but was borderline in production. In another case the productrnfailed in production. In the first case the large scale extrusion of linear polyethylene into castrnfilm was not expected to cause problems because it had worked successfully for years as a blownrnfilm. After one days production there was excessive plate-out on the chill roll which caused thernprocess to be shut-down. A sample from the chill roll was chemically analyzed in the SEM. Thernresults indicated that the plate-out was the additives. The plate-out problem was from 24,000rnlbs. Making it impractical to duplicate in the laboratory. Working together with the vendor thernstabilizer formulation was changed and a better solvent was identified to clean the rolls andrneliminated the problem. In the second case the new material was better than any previousrnformulations. A small trial batch, 1300 lbs. Was sent to production for a trial. It failedrncompletely because of excessive degradation.