High Temperature Masterbatch Manufacturers
Colliods are a renowned UK, USA and global distributer of High Temperature Masterbatch which has a huge variety of uses in multiple industries worldwide. We produce Electrical (E-TEC®) and Thermal (H-TEC®) solutions together with Film Grade Masterbatch and formulaes for the manufacture of cosmetics, food, electrical and electronic goods, toys, automotive interiors, medical equipment, automotive interiors and even artificial grass.
Custom Colour and Bespoke Masterbatch
Colour Masterbatch is available as a stock item in White and Black masterbatch, we also offer made to order bespoke colour match service with a together with a range of functionalities – anti-static, anti-block, anti-fog, anti-bacterial, UV stability and mould release being popular lines.
HDPE Pipe Compounds – Polyolefin Industry
Colloids is the recognised global leader of black and HDPE Pipe Compound colour masterbatches to the polyolefin industry for PE63, PE80, PE100 and PE100-RC pipe compounds. With a high level of dispersion, Colloids offer a lifetime guarantee of over 50 years at maximum-rated pressure and are proud to be the primary recommended masterbatch supplier of several process licensors. Contact Us to find out more or call to enquire further infomation at our UK Head Office on 0151 546 9222.
What Is A Masterbatch?
A masterbatch is a concentrated pre-dispersion of a pigment or additive in a carrier polymer. Masterbatches are designed to be diluted in the main polymer in the final processing step or in some instances in a pre-compounding stage.
The production of masterbatch is very similar to the basic compounding operation described above but the concentrations of pigments or additives are much higher to permit their dilution in the final stage. Production is carried out on dedicated compounding lines which are usually adapted to handle the higher concentrations of additives and ensure correct dispersion of the active ingredients. The actual concentrations of pigment or additive in a masterbatch vary depending on the type of material and the polymer type and also on the intended application. From an economic viewpoint it is good to aim for the highest achievable concentrations but there is usually a limitation imposed by the nature of the particular additive.
Near-Infrared (NIR) and Metal Detection
Considering some typical types of masterbatch based on a LDPE carrier (low density polyethylene) typical maximum concentrations for various additives would be as follows: carbon black pigment 50%; titanium dioxide (white) pigment 75%; erucamide (slip agent) 7%. In these three cases the limitation is imposed by the nature of the additive and the physical difficulty of incorporating levels above those shown. In other cases, the concentration limit may be controlled by the extremely low final use levels of a particular material, for example, the amount of colour pigment required to achieve a particular shade or the low use level of many polymer process aids such as fluoropolymer additives.
As with general polymer compounding and pelletisation, masterbatches can be produced in a variety of physical formats usually defined as ‘underwater’ (also known as ‘die face cut’) pellets or ‘strand cut’ pellets. Typically die face cut pellets tend to be offered with larger volume production runs and strand pellets with smaller runs but some companies would offer either type across the board. Perhaps rather perversely, it is also possible to convert masterbatch pellets back to a powder format. This is a relatively specialised type of product but would be used in situations where it is desired to modify a polymer which is itself in the form of a powder, without the housekeeping issues of using a pure pigment.
Masterbatch Industry Processes
Colour Plastic Masterbatches – Thermoplastic for Moulding and Extrusion
There are a number of potential ways of colouring or adding additives to a thermoplastic material. One could, for example, simply add pure powdered pigments to the polymer granules before the final moulding or extrusion process but this has a number of severe disadvantages. Many additives, particularly colour pigments, are extremely contaminating in their pure form and pose a real challenge in terms of cleanliness and housekeeping in a factory environment. It is also a fact that the majority of polymer processing machines which are designed to melt and shape a polymer material are not designed to properly disperse pigments, particularly at the low final concentrations often used.
Another approach which is still used in many applications is to pre-compound the polymer with the correct level of pigments or additives in an initial stage. This compounding operation involves melting and mixing the polymer and additives in a dedicated compounding line (typically a twin-screw extruder) before re-pelletising the compound. The pre-dispersed pre-coloured compound can then be supplied to a processing machine for final moulding or extrusion.
The compounding route has a number of advantages over direct pigment addition. When correctly operated it can ensure adequate dispersion and distribution of the pigment/additive. It also removes from the final processor the responsibility for controlling the levels of pigments and confines any contamination risks to a separate area. It does, however, have some economic and logistical disadvantages. Every gram of polymer being used has to go through the additional compounding/pelletisation route which adds significantly to the overall cost. Also, every variation in a formulation (for example different additive levels or different colour shades) requires a separate compound to be held in inventory.
All of these disadvantages can be overcome by using a pigment or additive masterbatch (these are sometimes also described as colour and additive concentrates). See: Extrusion, Injection Moulding and Compounding.
Another consideration in the design of a masterbatch is the selection of the carrier polymer. The carrier polymer has to be capable of dispersing the high concentration of additives whilst still retaining adequate processability in the final polymer and process stage. The selection of a carrier polymer is also important in its effect on the final processing step as shown by just one example. In blown film extrusion (tubular film extrusion) it may be thought to be very helpful to formulate a carbon black masterbatch with an extremely high flow (low viscosity) carrier polymer. In terms of achieving high pigment loadings in the masterbatch and easy dilutability at the film extrusion stage this may be true, but if carried to an extreme the introduction of a very high flow masterbatch into a very low flow film polymer may cause significant problems with the stability of the bubble on the extrusion line.
A type of application which is almost impossible to achieve using direct pigment addition is that of a specific colour matched product. Sophisticated and accurate colour matching may require as many as six different pigments within a formulation, the precise quantities of each being extremely critical. To achieve this by the direct addition of six different pigments in the correct ratios is almost impossible to contemplate. The production of a concentrated colour matched masterbatch, however, is perfectly feasible and can be achieved with a very high degree of precision in terms of colour tolerance. One of the most demanding areas where the achievement of complex colour matched formulations is required is in the production of automotive interior trim components. The use of multiple different polymer types and extremely high quality standards requires very tight tolerances on colour variation.
Masterbatch Functions – Antioxidants and UV Stabilisers
The use of masterbatches is not confined to colour based products but also applies to functional polymer additives, that is, those which are not necessarily visible in the application but have an important functional effect either within a process or in a final application. Such additives include antioxidants and UV stabilisers designed to preserve the service life of plastics, surface active ingredients such as anti-static agents, slip agents and polymer process aids which all change the behaviour of a polymer during processing.
In all of these cases a concentrated masterbatch provides an economic, effective and clean method of incorporating these materials into a final application. The concentrations of such additives in masterbatch are typically lower than for most pigment systems, firstly because of the difficulty of incorporating high loadings of these organic materials, but also because of their efficiency and low final application level. It is also possible to combine both visual (pigmentary) properties and functional additives in the same formulation and combinations of, for example, UV stabilisers and complex colour matched compositions are common.
The masterbatch industry provides valuable support to the polymer industry in general by providing clean, safe and efficient methods of handling the thousands of different pigments and additives used on a daily basis. Leading players in the industry are characterised by their ability to understand and support customer requirements, by their commitment to improving product quality and by a forward thinking attitude to investment in product research and development.
In practical terms, masterbatches can be incorporated into final products in various ways whether this is in a preliminary compounding stage or at the final processing operation. A physical pre blend of masterbatch and base polymer pellets can be made for feeding to process lines. This is generally a perfectly acceptable way to operate although in some cases care may be needed to avoid separation of masterbatch pellets from base polymer pellets in bulk storage. This is an issue which should be understood by a supplier of good quality masterbatch who will be able to address problems by the selection and control of masterbatch pellet size and geometry. The most common way of feeding masterbatch to a process line is by a dedicated feeder unit which may be one of various types, for example volumetric feeders or loss-in-weight (gravimetric) feeders. Such systems are accurate and reliable but again are dependent on the supply of good quality masterbatch in terms of pellet consistency and control of errant particles such as ‘longs’ and ‘fines’. Other aspects of product quality which should be controlled by reputable manufacturers are the obvious inherent quality aspects, such as colour accuracy and consistency. Adherence to compositional specifications such as pigment content and control of pigment dispersion is also paramount.
Quality Control and Masterbatch Production
Some masterbatch producers have developed laboratory and quality systems to the level of those seen in the major polymer producers themselves. Advanced analytical techniques such as FTIR spectroscopy, HPLC (high performance liquid chromatography) and advanced microscopic imaging are all used in the masterbatch industry.
Other more basic and time honoured laboratory techniques are used to control product quality such as MFI (melt flow index), monitoring dispersion by filter blocking analysis, and both visual and instrumented measurement of colour.
Potential quality problems with polymer masterbatches reflect many of those seen in the basic polymer industry. Poor pellet geometry and consistency can lead to feeding inaccuracies. Contamination of product can have serious consequences, both aesthetically and in performance terms and should be controlled both by good working practices (clean down routines and product segregation) and by robust inspection procedures, some of which lend themselves to automation.
Colliods Regulatory Compliance – Colour and Chemical Safety
Variation in colour (final product being ‘off shade’) is a potential problem, particularly with complex colour matched formulations and should be controlled by monitoring colour during production of masterbatch. It is a problem, however, which requires close collaboration between masterbatch producers and down stream customers because of other potential causes. These other causes can include measurement of colour under an incorrect type of light source (the same formulation for example can appear radically different when viewed under daylight and artificial light conditions). It is also always important to ensure that uniform colour standards are being used by the various parties involved in a collaboration. The film extrusion industry is a large user of masterbatch and the thin gauge of many extruded film products is susceptible to defects such as poor dispersion, high volatile levels and foreign polymer contamination.
The same masterbatch regulatory requirements found in the polymer industry generally also apply to masterbatch and reputable masterbatch suppliers should be able to confirm regulatory compliance with global product safety requirements. This applies to general chemical safety legislation such as REACh as well as individual national regulations on food contact approval and other toxicity issues. The range of materials used as carrier polymers for masterbatch is extremely wide as is the range of polymers in which they can be used. Large volumes of commodity polymer masterbatch are produced based on, for example, all types of polyethylene and polypropylene but suppliers can also be found who specialise in masterbatch based on engineering polymers such as polyamides, polycarbonate etc even down to highly specialised materials such as fluoropolymers.