Color Shift

[tbramel]

Looking for some help with a color issue that I have not seen before. We have a product that is molded from KingFa PA6-60GF. We have 6 colors for this part. I am having an issue with Yellow and Pink parts. After the parts are molded the color will change over time (8 hrs or more) to either a darker shade or lighter shade (usually lighter). I have done tests with the melt at the low spec of 250c to the high spec of 280c. The lower melt shows some improvement, but the color shift is still present. Currently waiting for the Master Batch supplier to send their Tech support for help. Looking for suggestions in the mean time....

[Pilot]

please check the parts also under UV-light. It looks, that hte color masterbatch can be degradated. Please check the processing temp. and residence time in the barrel. Please check also residence time in the hopper. Check also residence time in the dryer and temperature. Maybe the dryer is too big....

[rickbatey]

Colorant probably has the wrong carrier resin in it. Most likely, they're using HDPE and its not liking the base resin. Either that or they used a pigment package in the color that isn't high heat stabilized.
Rick