Well packaged

Things are about to get tough for the box. The box compression tester in the test laboratory keeps pushing down harder and harder on the empty box, which is made of highly durable corrugated cardboard, until the stress load totals more than 800 kilograms and the sides begin to bend.

Chemical laboratory technician Ralf Kranz, Head of Quality Assurance Packaging Management at Merck, is satisfied with the results, because the packaging for the company’s 2.5-liter glass bottles has withstood forces many times greater than the stipulated minimum stress load.

The cardboard also has to be resistant to humidity in subtropical regions and coastal climates. This is why weighed-down strips of it are hanging in an adjacent water basin in order to examine how the adhesive reacts to moisture.

Pressing, drilling, pulling, watering — the Merck packaging technology experts put every packing material to be used by the company through its paces in stringent tests that are based on actual material applications. First of all, there are tests that assess material suitability when new packing materials and innovative substances are developed, says Dieter Held, who heads the team of roughly 50 employees in the Packaging Management unit. In addition, the experts continually examine random samples in their labs as part of their quality assurance measures.

Last summer Held’s unit received the Gefahr/gut (dangerous goods) innovation award from the magazine of the same name for its development of a new method for testing the chemical compatibility of the materials used in polyethylene containers that hold hazardous materials.

Rather than employing Laboratory Method B, a complex and non-reproducible technique dating back to the 1970s, Merck instead uses a method that Kranz and his team borrowed from the Full Notch Creep Test (FNC) that is used in pipeline construction.

The team modified the process so that it could be used to evaluate hazardous material packaging in line with key security aspects. The associated tests examine how polyethylene reacts to contents such as surfactants, which can cause cold cracks.

The specialized FNC technique used with Merck’s polyethylene containers involves making a body block out of the plastic or else cutting it out of the container to be tested. This sample is then given a defined indentation that serves as the predetermined breaking point, after which it is placed for 21 days in the liquid product that it will later be filled with.

In the next step, the sample body block is stored in the original liquid product at a temperature of 50 degrees Celsius and exposed to a constant tensile stress of 150 Newtons. The extreme stress on the body block is removed on the 24th day; the packaging technicians then check the residual tensile strength of the maltreated plastic. Germany’s Federal Institute for Materials Research and Testing, which recognizes Merck Packaging Management as a testing facility, officially approved the new method in 2011.