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We have heard of a number of recent developments by previous speakers all of which could be utilised to some extent by masterbatch producers. The question that they need to address is how this technology can be best utilised in their products or processes to enhance, improve or make themselves more competitive, to create differentiation, to stand out from the crowd, to add value. To best appreciate these points one has to take an overview of the whole issue of plastic colouring in packaging applications.
The best starting point is where the colour is specified. This is commonly chosen by a marketing specialist who decides on the presentation, packaging and colour that makes their product more desirable. One should not underestimate the power of marketing. Colour sells, it makes a statement, it brands, and it makes a difference. A hundred years ago blue tinted bottles were used to identify their contents were poisonous. Today blue tinted bottles are used to promote the sale of a product renowned for its purity, namely mineral water! All due to the power of marketing!
The primary demand on the coloured masterbatch supplier is to obtain the specified or specialised colour, and it should be assumed that most achieve this. In truth the requirement is a little more complex.
The end user, or specifier, expects a regular, even colour, matching their original conception and fulfilling, or even exceeding their expectations, with regard to intensity, opacity and brightness while also meeting any relevant application legislation. Most colour specifiers are looking for something “new”, either a colour or effect which will make their product stand out from the competition and [unless the product is a deliberately confusable high street look-a-like] does not resemble any other brand.
On the other hand the processor however wants any easy, cost effective colouring solution to meet his customers’ demands with minimal cost and difficulty.
One of the most common complaints about a colour match from end users relates to the brightness or the intensity of the colour. Colours are frequently chosen from colour charts, paint finishes, ink catalogues etc., all of which are examples of highly pigmented, thin layer, surface coating technology, and it is not always possible to achieve the same effect with the typical levels of pigmentation associated with colouring plastics. Care in colorant selection, increasing pigment levels, using brighteners or fluorescent pigment/dyes can improve this but obviously there is a cost consideration. My message to the colorant supplier is, give us more intense, brighter colours, ideally with no extra cost premium! It is also important to understand what the specifier is trying to achieve and why. One of my customers, an injection-moulder, was a major supplier of packaging cases for watches and sunglasses to a well known, UK based, high street chain, clothing retailer. A senior marketing executive visiting one day was very impressed with the reception display of mouldings containing a well known European pigment supplier’s range of highly expensive, branded fluorescent dyestuff! He enquired further about the edge glow effect and was also shown mouldings in a slightly inferior, significantly cheaper regular fluorescent solvent dyestuff. The moulder was subsequently very surprised to receive firm enquiries for cases coloured in both dyes. A small number of cases coloured in the expensive, branded product for use in shop window displays, lit by an ultra violet light source for maximum consumer impact, the majority coloured in the cheaper dyestuff that the customer actually bought! An example of a marketing strategy that would probably not immediately occur to the masterbatch supplier and quite nicely highlights the importance by a retailer of getting a product noticed and what price one is prepared to pay for it! The influence of the colour specifier makes them as much the customer as the invoiced processor. While it is opportune to get a masterbatch specified for a job, it is a better long term investment to become the colour supplier that the end user consults about colouring his products. The masterbatch manufacturer is in an ideal position to make the interface between the marketeer, showing new innovations in colours and effects and to explain any technical or commercial ramifications that may occur.
The processors demands are relatively simple. They require a colouring solution that fulfils their customers [the colour specifier] requirements and is a cost effective solution. In order to produce the most cost effective solution one has to assume that the colorant blend and loading in the product compound is approved by the colour specifier. The colour suppliers’ task is simply to design a masterbatch that delivers this amount of the blended colorants in the optimum amount to obtain the most efficient use of the processing plant. To achieve this the following points have to be considered:-
1. The base polymer, its melt rheology and processing characteristics. This will define the generic type of carrier. In our polymer specific PVCu masterbatches the carrier is assembled at the same time as the colour component and, depending on the application process, this can vary immensely. For instance, two masterbatches producing the same colour food packaging sheet have significantly different carrier formulations when being run on a twin-screw extruder as opposed to a calendering line. The lubrication level [internal and external] differs in each to ensure maximum running speed of each process can be maintained and minimum plate out on the downstream handling equipment. This is not so remarkable when one considers that the base polymer formulations themselves differ from process to process.
2. The processing conditions which may be governed by outside influences. I know of a food packaging container manufacturer who injection moulds mfi 70 PP at 300C with little or no backpressure. This gives an exceptionally short cycle time on which they base all their costings. This cycle time is never compromised. The technical demand on the masterbatch to homogenise and function under these conditions is acute.
3. The quantity of colorant required with regard to shot size [injection moulding] or base polymer throughput. The quantity of masterbatch has to be realistic and possible to deliver. It would be unrealistic to dose regularly and distribute evenly a masterbatch designed to be incorporated at 0.25% into an injection moulding where the total shot weight was 2g [0.005g of masterbatch per shot!].This example is a little extreme but demonstrates the point. The size and relative density of both the masterbatch and the polymer granules has to be taken into account
4. To select a dosing level where the dosing system is running comfortably between its maximum and minimum limits. This ensures accurate, fine control of dosing and, assuming regular masterbatch pellets, minimum variation.
To be in a position to address all these points implies an intimate relationship between the masterbatch supplier and the processor. Indeed, it might be that, some companies would be happier working under the formal umbrella of a secrecy agreement. It also requires the masterbatch supplier to have a good working knowledge of his customer’s processes. We were recently asked by a UK moulder, Plasmotec of Brackley, Northants to look at the colouration of slip lids. Although a regular user of 1 and 2% masterbatches Plasmotec was anxious to establish the ideal solution for their slip-lid product. The same lid, which is colour controlled by spectrophotometer, could be run on more than one tool and one machine at the same time. Consistency, repeatability, minimal rejects and cost effectiveness where all taken into account. Evaluating each part of the whole manufacturing process and designing the colour package accordingly gave an interesting and unexpected result. After some changes to the installed volumetric dosing equipment [and evaluation of a gravimetric system] a nominal 4% masterbatch was settled on. With some modification to the mixing capability of the processing plant an excellent, repeatable result was achieved. Importantly, this dosing level allowed small dosing “tweaks” from line to line to standardise the colour due to slight machinery variations. These sorts of benefit to the processor are important. The colouring package has now been tailored to his manufacturing process to achieve optimum efficiency and hence the number of rejections attributable to colour failures should decrease. By involving the colour supplier in the manufacturing process, and lowering the reject rate, it should then be possible to tighten the QC limits for colour checks [dispersion, variation etc.] and change the sampling frequency based on greater levels of confidence so making a “better” product. This close relationship should offer advantages to both parties, improved efficiencies for the processor and a stronger tie or dependency on the masterbatch supplier. We should be asking ourselves but how often does this happen?
How to increase margins? This is a regular question for all business, not just masterbatch makers. One can always indulge in the time honoured occupation of screw-down the supplier! The plastic processor does it to his suppliers [us!] and we follow suit with ours, the domino effect! Alternatively with the right relationship with the processor the masterbatch supplier is well placed to make significant improvements to his clients [the processor] output rates which should result in more GM for the processor [more units per hour]. By the same token this improvement in output should result in more margin and greater added value for the masterbatch supplier. This can be achieved by using multifunctional masterbatch systems.
Composite masterbatches have been available for many years where, usually at the processors request, the colour package is combined with functional additives. Examples include u.v stabilisers, anti-oxidants, anti-stats etc. More recently, multifunctional masterbatches have been developed where the masterbatch contains the colour, carrier and process enhancing additives. The process enhancing additives work in a variety of ways. Most are polymer specific and their general purpose is to speed up the subsequent manufacturing process, to optimise whatever process is utilised to convert polymer to end product. It was during the development of polymer specific masterbatches for PVCu that we became heavily involved with incorporating processing aids and evaluating their subsequent effect in the next process. While PVC compounds are heavily dependant on process modifying additives some of this is relevant to other polymers. Additives that can be specifically utilised in masterbatches to improve the processability of the compound include:-
Lubricants, in very simple terms can be categorised as both internal and external types. Internal lubricants modify the viscosity of the melt. Chosen for their compatibility [readily soluble] to the host polymer they improve the flowability without any of the undesirable effects when changing the melt viscosity by changing the molecular weight. Obviously, care has to be taken when the application is blown film, blow moulding etc. where the extruded parison has to have great strength. Also, over lubrication gives screw slip which is detrimental to productivity and product quality. An appropriate level of internal lubrication however can improve throughput and hence efficiency. Typical internal lubricants include polyolefin waxes, fatty acid amides and esters, metallic stearates etc. External lubricants are by definition, incompatible with the host polymer and migrate to the surface between the polymer and the metal surfaces during processing. Again, type of lubricant is dictated by the host polymer and this kind of lubrication can benefit by reducing frictional drag, aiding release of components, and preventing melt fracture. Care has to be taken not to over dose to avoid problems such as plate-out, reduced weld strength and poor printability. Typical external lubricants include oxidised polyethylene wax, amide waxes and fluoropolymers. It appears that combination lubricant packages are more effective than single lubricants, probably due to the variety of efficiencies at different temperatures. Another benefit is that many of these lubricants assist in the breakdown of pigment agglomerates into primary particles so helping to achieve good dispersion and maximum development of the colour, again ensuring the most effective use of the pigment.
2. Nucleating agents are of particular importance in injection moulding applications. Their incorporation results in higher crystallisation temperatures and faster rates of crystallisation, which reduces cycle times. Nucleating agents can be inorganic [calcium carbonate, talcs, silica,
etc] or organic [salts of carboxylic acids, montan waxes etc.] compounds. Some polymers can also be used as nucleating agents, depending on the host polymer. Nucleating agents tend to be polymer specific and those that can be used across a range of polymers to have different levels of effectiveness in each.
3 .Proprietary multifunctional additives are becoming more common. Developed for specific polymers or applications, often their exact makeup is confidential, they are generally supplied in additive or masterbatch form [mouldwiz, timecut]. Usually claimed to improve processability, improve outputs and other visual and physical properties. Incorporating them directly into a coloured masterbatch does have the advantage of being able to see where they are!
Successful formulation of a multi-functional masterbatch has 2 benefits to the processor. It fulfils their expectations of a colouring solution and, because their production is enhanced, it creates added value. This additional value creates the potential for greater margins for the masterbatch supplier and demonstrates to his customer that he has more to offer than just the colouring solution. Being more creative is an important point in a market that is increasingly competing on price. This approach is being actively promoted by BASF with their “help our customers to be more successful” strategy.
To conclude, we need to work closely with suppliers to ensure we stay abreast of all new developments. We need to ensure our suppliers get quality feed back about these developments and what our customers are looking for in the future. We need to have a good understanding of what the end users are looking for, how we can best fulfil their expectations and how can we help our customers achieve this.
Colour Tone Masterbatch Limited
Pant Glas Farm Industrial Estate
CF83 8BJ UK
Telephone: +44 (0) 2920 888910
Fax: +44 (0) 2920 868487
Telephone: 01428 723211
Fax: 01428 722371