Colourings carbon black

Properties affected Colour carbon black also has useful anti-static properties, can provide electrical conductivity black pigments also give effective UV screening also used as a reinforcement in rubber compounds (the largest overall use)... 

Since acetal resins are degraded by ultra violet light, additives may be included to improve the resistance of the polymer. Carbon black is effective but as in the case of polyethylene it must be well dispersed in the polymer. The finer the particle size the better the ultra violet stability of the polymer but the poorer the heat stability. About 1.5% is generally recommended. For white compounds and those with pastel colours titanium dioxide is as good in polyacetals as most transparent ultraviolet absorbers, such as the benzophenone derivatives and other materials discussed in Chapter 7. Such ultraviolet absorbers may be used for compounds that are neither black, white nor pastel shade in colour. 

Colour. The colour of resins ranges from water-white to dark brown. Colour may be an important factor in resin choice depending on end use. Pale colours are necessary in some types of adhesives, whereas darker colours may be tolerated in rubber formulations, especially where carbon black filler is incorporated. Medium-coloured resins can be used in most adhesive formulations. 

Aromatic amines are the most effective primary antioxidants (Fig. 34) but they are discolouring and can only be used where the darker colours are acceptable (for instance in rubber adhesive formulations containing carbon blacks as fillers). The... 

Fillers. They are generally added to reinforce NBR adhesives. However, fillers can be added to promote tack, to increase the storage life, to improve heat resistance or to reduce cost. The most common fillers are carbon blacks. Precipitated silica can be used in applications where black colour is not acceptable, but excessive amounts tend to reduce adhesion. Titanium dioxide can be used to impart whiteness, improves tack and extend storage life. 

Soling which is compounded with light-coloured fillers instead of carbon black and thus does not leave unsightly marks on floor coverings. Nomogram... 

Carbon black should only be used as a colourant in flame resistant compounds, as carbon black supports combustion, burning readily in the presence of oxygen. 

Carbon Black. This is carbonised vegetable matter, i.e. very finely divided charcoal. Inevitably it is the most light fast of all colours. Obviously, it is only available as a solid. A common use is in liquorice products. 

A recent survey of the technical and environmental aspects of inorganic pigments by Schwarz and Endriss [33] has put the importance of these products into numerical perspective. Of a total worldwide production of some 5M tonnes of pigments, 96% are inorganic. Of this 4.8M tonnes, carbon black and various whites account for 84%, that is just over 4M tonnes. This means that world production of coloured inorganic pigments is approximately 0.8M tonnes. 

UV protection can be obtained with cheap carbon blacks (but colour is grey to black) or with expensive photostabilizers. 

There are specific grades and masterbatches of carbon blacks especially marketed as additives for conductive plastics. It should be noted that the carbon blacks modify other properties of the polymer, especially its colour. 

Two of the most important inorganic pigments are the white opaque titanium dioxide and carbon black. However, in this text we will only consider those pigments which are used for their colour, i.e. a specific absorption in the visible spectmm. The origin of the colour in inorganic pigments is due to one of the three following effects ... 

So far LII has only been applied for aerosol processes without the consideration of particles dispersed in liquids. First, investigations were carried out with re-dispersed carbon blacks. Besides furnace blacks (Printex A, G, 25, 35, and 55), various gas carbon black particles (FW 18, Colour Black SI60 and S170, Printex U and U140) were also considered. The particles were suspended in different liquids and dispersed by ultrasonic excitation. The stability of the suspension was recorded by measuring the aggregate size distribution (diffusion diameter) with DLS. Moreover, this was done before and after the LII measurements in order to control the stability of the particle suspension. To achieve LII... 

Section VII Colouring/De-colouring Recommended no colouring or de-colouring agents are recommended Tolerated natural active carbon Prohibited all colouring agents and carbon black from incomplete combustion of combustible fossils... 

In summary, carbon blacks work well as conductive additives for plastics and rubbers for applications other than power transmission, provided that a high-structure black and a suitable set of processing conditions are chosen, and as long as the black colour is acceptable. 

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