Custom compound solves colour consistency

10 August 2006

When Dawn Industries decided to introduce its Kwik-Tap ‘saddle tee’ connector for landscape irrigation systems, a material was needed with strength, toughness and dimensional stability. The company also wanted to differentiate its new product from the competition. That meant offering a new, improved method for making connections and creating a distinctive look. Soon after moulding started, however, Dawn discovered that keeping the bright orange colour consistent over time could be a problem. A solution was provided by Clariant Masterbatches.

The Kwik-Tap connection involves two different components: a ‘saddle’ that slips over polyethylene (PE) irrigation pipe and a ‘tap’ which threads onto the saddle, piercing the pipe wall and creating the tee connection without the need for tools. The saddle component is made of pre-coloured, 15% glass-reinforced nylon 6. The tap component, on the other hand, is subject to considerable stress as it pierces the PE pipe, so it is made from a 36% glass-filled compound.

Because of the glass reinforcement and complicated design, the tap component requires a large, heavy runner system. Consequently, Dawn has a lot of scrap to regrind and reprocess and, as production continued, they started having problems with colour. The bright orange was getting darker and darker and was never stabilized.

Clariant Masterbatches explains that when you introduce a high percentage of regrind, if you don’t use the right colorant and stabilizers it degrades during reprocessing, and that is why Dawn found the bright orange colour getting darker over time. The new material that Clariant supplied darkened slightly after the regrind was introduced, but the colour quickly became stable and consistent.