Right: Working on colour
materials | Colours & masterbatch Universal masterbatches using a carrier system that
formulations at Colloids
is generally compatible with a broad range of polymers are widely available across the globe, albeit in a limited range of colours, says Bestall. “However, this compat- ibility becomes questionable at high concentrations and where colour is critical. In the case of multi-component products made using two or more polymers, differences in colours are common. When assessing the colour of the various plastics used to make the product, the results are clearly lacking. It is nearly impossible to achieve the same colour in different coloured base polymers using a universal masterbatch. “A useful analogy to illustrate this colour variation is
to compare blackcurrant cordial when it is added to water and then milk. If you were to dilute 10ml of blackcurrant cordial with 60ml of water, you would get a full bodied, burgundy coloured liquid. Pour the same volume into 60ml of milk and the result would resemble a strawberry milkshake. The exact same thing happens when you add the same universal masterbatch to crystal polystyrene and ABS.” Bestall says that at high concentrations, which is the
way to mask an underlying base colour, deterioration in physical properties of the moulding is also possible. “The finished product application and manufacturing method should drive the choice of colourant,” he says. “Whatever the application, you must consider its performance in the field and decide on the most appropriate carrier. The closer the carrier is to the moulding polymer, then the higher the probability of success. “A polymer-specific masterbatch will allow good pro-
cessing and colour accuracy, without negatively affecting performance. For example, if your product is required to withstand the damaging effects of the sun’s rays, an additive can be easily added to the polymer- specific masterbatch’s unique formulation.” Universal masterbatches are readily available and can be accessed in smaller quantities, Bestall notes,
Ampacet worked with US company Zing Mini Discs to create unique products used in mini disc golf, in which players throw discs into baskets on a 9-hole “golf” course. The injection moulded discs are coloured with Ampacet’s Carnival masterbatch from its FusionFx products. FusionFx infuses colour at random into a moulded part, creating the vibrant splashes of colour in the Carnival products.
30 INJECTION WORLD | July/August 2017
“but if a polymer-specific masterbatch producer operates an agile production facility, the same is also true. Universals offer a limited colour range whereas the entire spectrum of 20 million colours can be readily accessed through producers of polymer-specific masterbatches.”
Another UK-based masterbatcher, Colloids (part of
Tosaf) takes a different approach. Technical manager Graham Cotton says the company’s Maxim Universal Stock range, which has been available for many years, “is based on a specific formula designed to work effectively in a range of polymers, provided the recom- mended addition rate is not exceeded. People use universals to avoid having to purchase the same colour in lots of different bases to give them better stock management and to lower costs; they are still very popular with lots of moulding companies.” Cotton says the universal carrier system has been
improved to increase compatibility with polyamides as well as 25 other types of polymer. The Maxim Universal Stock range includes some 200 colours. “So if a customer just wants, say, a green off the shelf, they can choose from 21 shades,” says product marketing manager Judy Wong. “It is ideal for small quantities from 1kg upwards with next day delivery.” Colloids also offers a bespoke colour and carrier
service. Over the last 12-18 months it has also made “significant” advances in the colouration of polyesters to improve colour distribution and the ability to use a wider gamut of colours, including fluorescents and special effects. In addition, it has formulated masterbatches to
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