The Masterbatch industry is young. It was only in the late 1960s that what is nowadays everyday life became apparent: plastic products in an almost infinite variety of colours. Half a century prior, a “master” controlled the rubber-sulphur-carbon black mixture in tyre production, the “masterbatch”. A term that today means customer-specific colour and additive concentrates.
Great inventions were made in the late 60s and early 70s. Technologies came about which today are not only an essential part of our daily lives, but just as self-evident as the diversity of colour around us. Just consider the office desk: a conspicuous, dark grey-blue mouse pad, a royal blue magazine rack and a simple mouse grey pencil holder. Not to mention all the equipment, like the matte-metallic silver laptop with black-edged screen, the half white, half matte silver-grey designer desk lamp, the deep black dictaphone or the elephant grey telephone.
Even when practicality prevails and the colours of a child’s bedroom are unquestioned, the multitude of plastic items in the workplace show what masterbatch manufacturers are doing today. They can provide a highly concentrated individual colour cocktail for almost every thermoplastic product, finely mixed with the base plastic and other additives for light protection or weather resistance, for example. In this way, manufacturers match the colours of each of their products precisely while also giving them the desired properties.
Colour nuances instead of uniform colour
Things looked somewhat different in 1960 when plastic products became popular. Colours were limited and basic colours prevailed: white, black, grey, uniform blue, green, yellow and red. Unusual colours were rare. This began to change in the early 70s, initially at a very slow pace. The shocking orange telephone seemed revolutionary. Glittery turquoise plastic suitcases, pastel toys, marbled kitchen utensils: these are inventions of the 70s, 80s and 90s.
Without the masterbatch industry, they probably would not exist and the world would be a far drearier place.
Masterbatches give colour to thermoplastics, that is, fusible plastics. And because manufacturers can use a broad range of raw materials to compose them, the variety is almost infinite. Masterbatches increase the value of plastic products and contribute to their economic success – they turn “cheap plastic” into a socially acceptable product with a great look and feel.
Tyre manufacturers at the turn of the century before last must have been ambitious. They noticed they were only able to obtain a good result by homogeneously mixing additives and pigments of sulphur, zinc oxide, chalk, and later also carbon black into the rubber mixture. The components that are difficult to disperse were thoroughly mixed together before being added to the rubber. A “master” checked each batch of rubber plus the pre-dispersed pigments – this is how they were circulated. But once heated, the entire batch was wasted if the mixture was incorrect. The “masterbatch,” however, guaranteed good results and durable tyres.
More than 50 years later, the term was to become a quality criterion for the fashionable admixture thermoplastics. This was probably due to processing technology. Starting in the 1920s, tyre manufacturers used the so-called Banbury mixer designed by the engineer Fernley H. Banbury to intensively knead their rubber mixes. The discontinuous kneader introduced high shear forces into the highly viscous mixture and optimally distributed the reaction components in the masterbatch.
Perfect distribution in a masterbatch was also important for manufacturers of plastic products. The triumphant march of plastic began in the 1950s. Thermoplastics, especially polyolefins (e.g., polyethylene (PE), polypropylene (PP)), styrene plastics (e.g., polystyrene (PS) and copolymers such as ABS) and polyamide (PA) became extremely popular materials in various industries from toy manufacturing to automotive engineering. They could be processed using extrusion and injection moulding processes, but one of their greatest benefits was the multitude of colour possibilities they created. Thermoplastics could be coloured by melting and solidifying them together with colourants. But masterbatches had not yet been invented. The powder base polymer was mixed with powder pigments and additives and then compounded; meaning they were melted, dispersed and mixed by conveying through an extruder. This is how the polymer industry produced large batches in standard colours. Special requests could not be economically produced in smaller batch sizes. Processors who wanted smaller quantities of a non-standard colour had to mix the paint powder with the plastic itself – a dusty colouring process that often failed to achieve the desired result.