Clariant: Competence and experience in the in-house colouring of ABS

In-house colouring of thermoplastics and elastic polymer blends such as ABS has been used in the industry for many years to manufacture high quality engineering plastics components. The Plastics Industries BU of the Pigments and Additives Division, Market Segment Masterbatch & Compounding in Gersthofen, has worked on raw materials formulations for in-house colouring of ABS for some considerable time.

ABS belongs to the group of elastomer-modified thermoplastics. When manufactured by the emulsion or suspension processes, variations in inherent colour often occur. During processing, exposure to high temperatures may lead to undesirable yellowing which renders the task of in-house colouring more difficult. To achieve high quality nevertheless, the opaque raw material should exhibit inherent colour, which is as light and uniform as possible.

Extensive research by Clariant’s experts into optimised formulation has perfected the in-house colouring process as regards colour yield and freedom from streaking. Temperature control, type of mixer and the formulation of dispersing agents are particularly important for successful colouring.

Besides optimal pigment dispersion, specially matched dispersing agents and carrier substances based on wax prevent deterioration of the ABS to be coloured. Furthermore, the mechanical, thermal and rheological properties of the material are retained after colouring. The formulation is adjusted to be compatible with the plastic to be coloured.

Specially designed extruder screws and temperature controls are other useful methods for achieving an optimum result without streak formation. High quality constituents in the formulation, such as pigments with low filter values, are further key factors for manufacturers of masterbatches and compounds.

Colour changes necessary at the compounder can be undertaken at any time.

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