Pigments for Engineering Plastics

Increasing use of engineering plastics for visible applications, such as equipment housings, produce a demand for good colours that remain stable at higher processing temperatures, 

Yellow chromophtal GTAD (Ciba) is an anthraquinone-based material and is self-dispersing in resins and polyolefin fibres. Unlike classic pigments, it recrystallizes on return to ambient temperature and so offers a high thermal stability (up to 28()°C). The pigment is also transparent and non-warping. 

A range of encapsulated heavy-metal-free single-pigment dispersions and custom colour matches that can be added at any point in the compounding process, developed by Holland Colors under the name Engineering Holcobatch, is claimed to improve the properties of filled (mainly glass-filled) plastics. 

Organic yellow, Bayplast Yellow G Y-5680 (Bayer), exhibits a unique spectral curve with heat stability and light fastness. It can be used with most thermoplastics, including polycarbonate and nylon (processing temperatures up to 32()°C have been obtained). Cerdec s chrome titanate yellow is also recommended for engineering plastics, because of its above-average heat stability. 

The research could be important for the packaging industry, where some problems have been encountered in tamper-proof bottle caps moulded in compounds using phthalocyanine blue. 

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