Topping the Bottle

Polymer replaces brittle ceramic stopper

For many beer drinkers the ceramic re-sealable bottle closures used in some premium brands will be well known. However, this is an expensive bottle design that relies on the bottles being returned to help reduce costs. The ceramic stopper, which is non-recyclable, is quite brittle and can be damaged during the return process. Furthermore, the printed logo, which requires an additional production operation, can fade or wear away. 

The key technical challenge facing beermaker Grolsch Bierbrouweij, Netherlands, was to re-design the stopper using polymers that retained the traditional appearance of a ceramic stopper, while employing materials that improve productivity. The permanence of the logo was also highly important. Of course, the finished molded product had to preserve the visual and tactile qualities of the original.

The Grolsch design team, the German mold-maker Foboha and the Dutch processor Reobijn, collaborated for over a year with engineers from PolyOne Th. Bergmann, Polyone’s compounder in Gaggenau, Germany, to develop, test and perfect materials that could be injection molded to replace the ceramic stopper and the printed logo. A particularly demanding challenge, successfully overcome after several trials, was matching the red color of the Grolsch logo. 

MAXXAM mineral-filled, red polypropylene (PP) was chosen as an accurately color-matched material for the main body and logo of the replacement stopper together with an unfilled white PP to form the skin via a 2-shot injection molding process. Both formulations were developed and produced by So.F.teR., PolyOne’s joint venture partner in Italy.

Collaborating closely with the Grolsch design team, mold-maker Foboha and processor Reobijn, PolyOne’s engineers demonstrated their ability to apply polymers to an established market. The team successfully designed a new stopper more durable, less expensive and more efficient to produce. As an additional bonus, there is no discernible difference as far as the all-important consumer is concerned.

—SG

For more information:

Circle 334—PolyOne, or connect directly to their website via the Online Reader Service Program at www.rsleads.com/202df-334