Ultramid® (Polyamides)
In principle self-coloring of the Ultramid® polyamides by the processor is possible. However, we advise against self-coloring of Ultramid® T (which is generally processed at temperatures above 310°C) due to the limited thermo stability of the coloring agents. The properties of parts made from self-colored granules, in particular homogeneity, impact resistance, flammability and shrinkage, must be carefully examined because they can be influenced to a high degree by the additives and the individual processing conditions.
In the case of three-zone screws, the homogeneity can be improved by raising the dynamic pressure. However, this measure simultaneously increases the dissipation and therefore the temperature load of the melt. The throughput may also fall. The mixing action of the three-zone screw is therefore limited, which means that screws with shearing and/or mixing sections may have to be used. Barrier screws are equipped as standard with shearing and/or mixing sections and are therefore suitable for self-coloring. When self-coloring is employed with glass fiber-reinforced grades, it is recommended to use types of steel that are especially protected against wear in view of the greater abrasive effect.
Ultramid® grades that are UL94-rated must adhere to the stipulations of UL 746D if the UL rating is to be retained. Color batches having special UL approval are needed for the self-coloring of Ultramid® grades bearing the classifications UL94 V-2, V-1 or V-0, whereas in the case of the classification UL 94 HB, the use of color batches bearing a generic UL-rating is sufficient.
If self-colored parts are used in the food sector, special regulations have to be observed.
Color Batches for Ultramid®:
BASF Color Solutions
Treffert Polymer-Technology
