Whether you’re an injection molder, blow molder, profile extruder, or sheet extruder, processing clear polycarbonate has similar challenges. Maintenance Managers and Production Managers typically face significant downtime, scrap, and cost associated with color changes (dark to clear) and/or contamination (black specks) during processing. Similarly, performing a material change from any other resin into a clear polycarbonate can be a difficult transition as well. If you happen to be shutting down on clear PC black specks are inevitable on start-up.
The use of purging compounds has been a valuable tool in minimizing the time and cost associated with these issues, but the purge compounds themselves can add post-purge fogginess or milkiness or residue that can last long after the purge process is complete in clear polycarbonate.
Commercial grade purging compounds consist of ingredients that perform the cleaning whether it’s a mechanical or chemical purge and a carrier resin. It’s of no benefit if you are able to clean the machine but can displace purge residue after the purge process. This is especially important when running clear polycarbonate. The residue can come from the ingredients that facilitate the cleaning, the carrier resin, or both.
Asahi Kasei has developed a new product called Asaclean PLUS. It’s a concentrate. It has all the active ingredients of our best chemical purge minus the carrier resin. It’s mixed with whatever resin you’re processing including clear polycarbonate. We’ve found that mixing 20% Plus to 80% resin will clean very effectively with minimal residue that’s easily displaced. Since it’s mixed with the polycarbonate you’re processing (virgin or clean regrind) there are no resin incompatibility issues which will significantly prevent post purge issues.
In the case of injection molders, it’s moldable and can be used in screw and barrel cleaning and open or closed mold purging if running a hot manifold or hot runner. It will make parts. For extruders, purges can be done on the fly. In both cases, it can be used as a shutdown purge. In my opinion, if you're running clear polycarbonate Asaclean PLUS is worth evaluating.
Learn how to reduce machine downtime with five quick purging compound tips for your injection molding application.
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