blueing after ageing of rigid PVC with stab Ca/Zn ?

[BE05157]

In contrary to what we expected, a rigid PVC sheet (kw 66), stabilized with Ca/Zn soap (3.5 phr, with anti-UV Tinuvin 320 is becoming blue after ageing in a weatherometer. We suspect interaction between stabilizer and anti-UV. Do you have already heard baout something like that ?

Best regards

Xavier

 

[Demon3]

Yes, we have a sample of very blue PVC in the office that was degraded due to excessive heat in the extruder. I can well imagine that the stabilisers are the cause. Ask Ciba, they should know as they are the leading supplier. It's their additive and so they should be willing to help you.