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| Author | Topic: Extuding PP, sheet |
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awan Senior Member Posts: 8 |
posted July 28, 2009 01:16 PM
  
We have the intention of converting an existing 6 inch extruder running PS to extrude PP sheet (about 0.030" thick) I know we need to change the screw to a PP Barrier screw, any other specifics I need to know? Also how about the roll stack, anything in particular needs to be modified/upgraded. I heard something about the surface finish, anyone know about that? Thanks. IP: Logged |
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Tom C Moderator Posts: 948 |
posted July 30, 2009 11:21 AM
http://www.southlandpolymers.com/products/Polypropylene/FPC%20PP%20Ext%20Guide.pdf ------------------ Tom Cunningham www.ExtrusionTechnicalServices.com IP: Logged |
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awan Senior Member Posts: 8 |
posted July 30, 2009 11:37 AM
Thanks tom , aslways good, but I need inof on the polishing roll and chill rolls, anyone know whether I can use an existing configuration that is currently making PS sheet for PP? without any changes or modification? IP: Logged |
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Tom C Moderator Posts: 948 |
posted July 30, 2009 12:32 PM
Can't find any specific mention of surface finish for PP chill rolls except having to do with gloss, which may mean it is not an issue. Matte surfaces are used without release problems. Chill roll temperature is important, lower makes more transparency and toughness, higher allows more crystallinity increasing stiffness. PP holds more heat than PS and may produce a higher melt temperature increasing roll heat transfer requirements. A few interesting things here: Good luck. ------------------ Tom Cunningham www.ExtrusionTechnicalServices.com IP: Logged |
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Steve H Moderator Posts: 418 |
posted July 30, 2009 10:11 PM
Awan, I've successfully run Homopolymer and CoPolymer PPs on a HIPS sheet line, there'll be about a 30% penalty in output. An L/D of 27, with a 3L/D mixing section seemed to work OK. You'll want good temp control on your chill rolls, less than 1C variation across the roll from inlet to outlet, no blocked galleries in the rolls to produce hot spots. Steve IP: Logged |
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awan Senior Member Posts: 8 |
posted July 31, 2009 10:41 AM
Steve, great !! But I will be ordfering a new barrier screw designed for PP 6"/1:30 and block the vent. So hopefully I will not loose too much capacity. Then I should not be worried at all with the surface finish of my polish rolls. I've heard they can be sticky for PP. IP: Logged |
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awan Senior Member Posts: 8 |
posted July 31, 2009 10:41 AM
Steve, great !! But I will be ordering a new barrier screw designed for PP 6"/1:30 and block the vent. So hopefully I will not loose too much capacity. Then I should not be worried at all with the surface finish of my polish rolls. I've heard they can be sticky for PP. IP: Logged |
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Steve H Moderator Posts: 418 |
posted July 31, 2009 04:15 PM
Hi Awan I didn't experience any problems with PP sheet adhering to the chill rolls (Highly polished, mirror finish- which we used to produce clear Block CoPol PS/GPPS sheet) Somewhere in my files, I got some more info on PP, which I'll dig out when I can. Steve IP: Logged |
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Tom C Moderator Posts: 948 |
posted July 31, 2009 04:33 PM
PP in general does not like to stick to metal, which is why it also has low extrusion rates. It can't build much pressure in the beginning of the screw.
Tom Cunningham [This message has been edited by Tom C (edited July 31, 2009).] IP: Logged |
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awan Senior Member Posts: 8 |
posted August 12, 2009 10:06 AM
So yes I have confirmation from equipment manufaturers, my existing chrome rolls will work out. All I need is ave a new barrier screw made, barrel honed, vent plugged and off I go, thanks all for your input. I will follow up with the outcome and experience in a few months. IP: Logged |
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Tom C Moderator Posts: 948 |
posted August 12, 2009 04:36 PM
Please support this web site by allowing us an opportunity to quote your screw and barrel needs. Please find my contact information at my web site. ------------------ Tom Cunningham www.ExtrusionTechnicalServices.com IP: Logged |
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