Question about Bismuth presence (as contaminant) in injection mouldsurface, after injecting PP

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

Reply to
Gino Ferrero
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Does the PP contain a fire retardant? Has the customer mixed in some regrind?

Ernie

Reply to
Ernie

Il 30/06/2011 21:29, Ernie ha scritto:

Yes, the PP was partially regrind.

Reply to
Gino Ferrero

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. ...)

Reply to
RolfWissmann

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.

Reply to
Stewart

Or the loading could be very high/poorly compounded and plating out on the tools.

Reply to
Stewart

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