Blackening Based on Nigrosine, “Made in Germany” AF-Carbon® PA 950509 black

Carbon black is typically used for black coloration of PA polyamides 6 and 6.6. High-grade carbon black masterbatches are used in order to ensure intensive and reliable results of direct coloring of compounds. However, carbon black, as the coloring matter, is used to its limits in a few application cases with great demand from the technical or aesthetical aspect. Soluble dyes clearly prove to be advantageous here. They are not coated with the polyamide matrix as in case of pigment particles but directly color the matrix deep black.

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PA 6 GF 30 plates, colored with PA 950532 black as compared to a standard nigrosine black according to 550 h QUV tester [ASTM G 154 C1]

The positive influence of AF-Carbon® PA 950509 black in terms of rheological and mechanical properties is accomplished with a special quality of raw material. It also facilitates production of deep-black products having clearly better surfaces and high luster in compounds which are glass-fibre-reinforced or flame-protected. The influence of useful properties such as impact strength, strength and elasticity stays minimal.

This type similarly improves the processing properties. Nigrosine is soluble in polyamide and does not result in increase in viscosity as in case of carbon black. It facilitates a better mould filling. The special formulation of the masterbatch makes open a vast expanse of the processing window. This is achieved by reducing the recrystallisation temperature from 12-17 Kelvin. A new element here is that this effect is achieved both in PA 6 as well as PA 6.6. In addition to an improved mouldability, clearly improved results are achieved in gas- or water-internal pressure applications (GID, WID) and even in foam injection moulding processes.

»As compared to the carbon black masterbatches, nigrosine coloring agent masterbatches facilitate blackening with least possible influence on the useful properties of the finished product. High degree of gloss, deeper black tones and better surface qualities are achieved specially in filled polyamide compounds. Special products, which combine the benefits of carbon black and coloring with colorants, are suitable for outdoor applications with high requirements«


Very strict requirements were set with regard to emission, particularly in the automobile sector. AF-Carbon® PA 950509 black is based on very pure and low polluting raw materials. Emission behaviour was compared in various studies based on VDA 278. PA 6.6 compounds, which were colored using AF-Carbon® PA 950509 black, exhibited a VOC value that was almost 25x less as compared to compounds which were produced using the conventional nigrosine masterbatch.

UV Stability

Nigrosine is an organic coloring agent and has a light- and weather-resistant property, which is clearly inferior to coloring using high-grade pigment carbon black. This void is filled by AF-Carbon® PA 950532 black. Durable protection against UV radiation is possible in an extremely high-grade carbon black. At the same time, a deep-black color with all advantages of the coloring agent can be achieved for processing by adding some amount of nigrosine.