Colorants and base resins - mixing

[mwohlg]

Hi all,

I have one project that uses a Schulman natural nylon 6,6 (GF50) with a blue and a gray variant. I have another project that uses a DSM natural nylon 4,6 (GF30) with a green and a tan variant. The blue and gray colorants are from a different supplier than the green and tan colorants.

If my second project's customer wants to get a third version of their part in gray, can I use the gray colorant that is intended for the PA66GF50, or do I have to get a gray colorant that is especially intended/formulated for the PA46GF30? (In case it matters, the green and tan colorants are in nylon 6 carriers, but I don't know what the carrier of the blue and gray colorants is.)

Thanks!

[Suhas]

Hi mwohlg,
Most nylons are compatible with each other. You are also adding a small % and so in my opinion it should work. How critical is the project? Does it need FDA approval and such? In which case it may be best to do some testing. Another factor is the large % of glass you have, I think it should be fine.
Please let us know what you find. We would like to learn.
Suhas

[rickbatey]

As Suhas pointed out, they base resins should allow you to use the color for the other part, as long as not FDA compliant. I would mold samples and test ASAP so that you can discover any hidden issues (like loss of impact, UV, or Creep loss). Although rare, you will find a carrier resin not compatible with your base resin.
Rick.

[mwohlg]

Thanks guys,

As it turns out, several years ago we had run samples with the "correct" colorant, so now we are just trying to find that part number and get some more of it. We'll have 3 different gray colorants in the facility (1 for PBT, 1 for nylon 6,6, and 1 for nylon 4,6) so hopefully we won't get them mixed up. You know how sometimes "black is black" :-).

The application is automotive, so we didn't want to rush through and use a sample material that was not intended to be used for production also. Once you get something approved, it takes a global crisis to get it changed, and then only temporarily. We decided to take the extra time and use the "correct" colorant, now that we've identified it.