Leave it to Merck to create an effect

Rotomolding news tends to be rather far and few between. So if there are developments to report, we take care to do so. Because there is more to rotomolding than large hollow items—think recycling bins and water storage tanks— alone. These days, the technology is increasingly being used as a cost-effective alternative for the production of, for example, decorative parts for toys or sports products—a development which is being helped along by the growing range of decorative applications now available to rotational molders.

At the Fakuma trade show in Friedrichshafen this week, the Performance Materials unit of the Merck Group (Darmstadt, Germany) was presenting one of their newest decorative effects for rotomolded products: pearlescence. Merck has come up with a highly innovative way to achieve long-lasting pearl luster effects in rotomolded products.

According to Thomas Kern, Marketing Communication Manager Pigments & Functional Mmaterials, the product is ‘unique.' “Of course, pearl effects have been around for a long time, but in rotomolding, they’ve always presented a challenge,” he explained. “The problem was, during the rotation of the mold, the pigments world all move towards the inside of the mold. So the whole effect of the pearl was on the inside of the product instead of the outside.” Another problem was that the pigments would often not mix well with the base polymer used, and therefore would not be distributed evenly. “It was very difficult, well actually it was impossible, for rotomolders to achieve the effect they wanted,” said Kern.

Merck successfully developed a technique that addressed these problems. “The pigments are flake-like in structure,” said Kern. To prevent them from clumping together Merck came up with a novel solution: “We glue them onto tiny glass balls. That way, we ensure that they spread evenly in the polymer, and create an effect that lasts. It’s a real breakthrough, and it works. No one else can do this.”

Up to now, the especially formulated pigment preparations have been made available in a silvery white color, red and gold. “Gold and silver are our top colors,” said Kern. “But more will follow.”