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| Author | Topic: Gels Caused by Re-processed PE |
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RBaratt Senior Member Posts: 13 |
posted March 22, 2005 02:14 PM
   
I run 14% re-pelletized film scrap back into trash bag lines, all runs well until we hit a "bad" batch of re-grind that causes excessive gels in the film. Sometimes we are able to drain a thousand pounds from the silo and then the gels go away. This intermittent gel problem is a constant source of aggravation. The gels appear to have the same color as the base resin so I suspect it may be unmelted resin. I do not have the luxury of slowing down the line to see if the problem goes away. The problem does go away when I remove the re-grind from the process. Is re-grind harder to melt? I thought that having been through several passes with added heat history the polymer chains would have broken down and made re-grind easier to melt than the virgin resin. Or do I have a degradation problem, excessive crosslinking from some of the Re-processed pellets. No testing has been done on the re-pelletized product and I am not sure that there is an easy test to determine re-pelletized product quality. We process about 15,000 lbs.of re-pelletized product each day. Any suggestions or advice would be greatly appreciated. IP: Logged |
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Tom C Moderator Posts: 488 |
posted March 22, 2005 06:20 PM
Richard, Check your gels and your screen pack microscopically. Often you can see something that will lead you to a solution. If it is an umelt problem, slowing the extruder usually will help (even if it is only to prove an unmelt problem). How about a tighter screen pack? I also have many other tools to assist in resolving these types of issues if you were interested in professional help.
Tom Cunningham
Extrusion Technical Services [This message has been edited by Tom C (edited March 22, 2005).] IP: Logged |
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Bob Cunningham Senior Member Posts: 104 |
posted March 26, 2005 07:33 PM
What process do you use to repelletize? Could you be crosslinking during your repelletizing process? Is there any chance for contamination (i.e. temporary storage in gaylords or something)? IP: Logged |
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