Most of the people involved in Engineering Polymers parts production, understand difficulty of Glass Reinforced material based coloring.

Not all knows the opportunity to avoid this difficulty with the introduction of Vydyne™ PA66 material grades. We need to consider firstly that the glass fiber is an inert component of the blend, and although a thickness of few microns, it does not accept colorants and causes opacity in the finished molded part. The glass transition phase of PA66 appears between 70°C and 90°C – G.R. version included (for PA6 from 50°C to 80°C).

This value should be the minimum limit of heat in the mold in order to obtain an acceptable part surface and the best mechanical properties. Increasing mold temperature up to 95°C, the percentage of «frozen skin» is reduced and forces glass fiber into the PA structure. This action produces a shining surface finish and a most homogenous polymer structure.

In the case of molding in color with masterbatch, In the masterbatch the quality of the carrier and thermal stability of the pigment become relevant. Given that in the glass reinforced polymers glowing effects resuts are not reproducible. A dry blend solution with unr. material could help getting the best surface aspect. It is the case of automotive device made of Vydyne™ material where the surface contact of the gasket requires a bright surface finish part as in the picture.

Image: Vydyne ™ R530H (PA66 30%GF) + Vydyne ™ 20NSP (PA66 unr.) in dry blend solution by M. Francescon