Recycled polypropylene issue

[mdezelon]

We mold garment hangers and recently purchased recycled PP from a reputable supplier. We had one batch that reacted to cotton fabric that left yellow marks on the garments. The hangers were black in color, but no surface oil or residue was present. The reaction was sporadic, not all hangers or garments were marked.

Can anyone advise why the sporadic reaction between recycled PP and fabric?

[rickbatey]

Perhaps the issue was a plasticizer that leached out of the molded parts over time? For it to be yellow, I'm thinking some kind of oil but it could have been an internal mold realease as a wax.
Rick.

[Len]

Perhaps the issue was a plasticizer that leached out of the molded parts over time? For it to be yellow, I'm thinking some kind of oil but it could have been an internal mold realease as a wax.
Rick.

Agreed. Something is migrating. It could be a fugitive dye or antistat additive used in the recycled black. Plasticizers are not usually used in PP, but I've heard of processors adding mineral oil to enhance color dispersion or to aid processing. A liquid color carrier could also be at fault.

Len