The Extruder:
The core machine of the masterbatcher
A single or twin-screw extruder with electric motor that drives long worm shafts in a cylinder is the most common machine for producing masterbatches.
From kneader to extruder
The first masterbatches were produced with kneader technology from the rubber industry. The name "masterbatch" also comes from this field. Soon, extruders were developed that could better disperse the thermoplastic materials, fillers and additives in the compounding process. In some cases, a premix of the additives is used. The extruded strand is then pelletised. Masterbatch manufacturers use strand or underwater pelletization for this. Water-sensitive products are air-cooled.
Extruders are still the first choice for standard thermoplastics today. The technology behind them is constantly being improved. The same goes for the mixers: new designs have allowed better homogenization of the premix. Moreover, the development of gravimetric metering has made the premix partly unnecessary.
Colourful brilliance thanks to new pigments
As the carrier polymer, the masterbatch manufacturer generally uses the polymer to be coloured by the processor. Colourists compose the required colour from various pigments and use additives to achieve the other properties of the plastic product. Polyolefins and polystyrenes were initially coloured with inorganic pigments that could withstand the process temperatures. The development of heat-stable, organic pigments in the 1970s and 80s facilitated the production of a greater variety of brilliant colours. Plus, new colourants hit the market not too long after which enabled metallic and gloss effects and transparent shades. At the same time, an increasing number of additives expanded the range of thermoplastic applications: UV absorbers, for example, ensure resistance to sunlight in numerous plastic items today and other functional additives improve heat ageing. The latest additives make plastics laser-markable, heat-absorbing and even provide forensic safety features that make product counterfeiting more difficult.
Uniqueness as a success model
Today, masterbatch manufacturers use a wide variety of techniques and materials. Only by combining them correctly can the different requirements and objectives of the manufacturers of plastic items be met. In the 1970s, these new application possibilities were hardly imaginable for any manufacturer or user of the then new masterbatches.
