Dear fellows, one of my customers find Bismuth (yellow powder) on injection moulds surface after injecting PP. I've been asked about the possible origin of such contamination: Any idea ? Thanks
Gino Ferrero
Question about Bismuth presence (as contaminant) in injection mouldsurface, after injecting PP
Jun 30, 2011
5 Replies
Does the PP contain a fire retardant? Has the customer mixed in some regrind?
Ernie
Il 30/06/2011 21:29, Ernie ha scritto:
Yes, the PP was partially regrind.
Does your PP contain a "Radiopacifier" based on Bismuth Trioxide
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which partially ends up as a mould deposit?
If so, perhaps the molding conditions need to be adjusted (less shear, lower temperatures, kitchen sink, etc. ...)
If bismuth trioxide is compounded into the resin and it is showing up as residual on the processing equipment, one should also go back to the compounding process. There are numerous issues that can be created in the compounding of radiopaque fillers, and the bismuth trioxide can on of the more problematic ones.
Or the loading could be very high/poorly compounded and plating out on the tools.
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