Scratch-Resistant and Cost-Effective - Wacker Chemie AG


Scratch-Resistant and Cost-Effective

WACKER chemists Dr. Klaus Pohmer and Dr. Michael Geck, together with development engineer Oliver Fuhrmann (from left), use an interior trim to demonstrate how silicone additives increase the scratch resistance of plastic.

The results of these and further tests show that GENIOPLAST® Pellet S reduces the plastic’s surface friction, thus improving the scratch and abrasion resistance. Furthermore, this does not adversely affect the plastic’s mechanical properties. “On the contrary, tensile strength and stiffness are actually enhanced,” reports Dr. Klaus Pohmer, who is in charge of global business development at WACKER SILICONES’ Performance Silicones business unit. He explained that the tests also showed that the modified plastic did not become tacky when exposed to ultraviolet light. That’s why interior parts made of modified polypropylene still feel good even after intense exposure to sunlight.

GENIOPLAST® Pellet S performed very well in the fogging test – as did the two silicone-based competitor products – whereas the organic additive displayed considerable weaknesses here. Unlike the organic additive, the long-chain silicone does not migrate out of the polymer, even at high temperatures. Thanks to the WACKER product, unpleasant odors and blooming of the active, as well as its undesirable deposits on the windscreen, are finally a thing of the past.

“The challenge was to transform an ultra-high-molecular silicone into an easy-to-process, solid product form.”

Dr. Michael Geck Application Technology

Crockmeter Test

The crockmeter test involves a test probe covered with a cotton cloth rubbing the same section of a test panel (made of the test plastic) several times with a specific force. The frequency of the test probe’s back-and-forth movement during the test and its downward force can be adjusted on the test device. The test panel is subsequently inspected visually. If the surface of a dark test panel is very sensitive to the repeated rubbing, the stressed area takes on a shiny appearance; if it is not sensitive to the rubbing, its appearance is unchanged. Erichsen’s Lineartester 249 is used as the test device. The test panels made of plastic modified with GENIOPLAST® Pellet S performed best in this test, while those with the organic competitor product were the worst performers.

“Since our additive makes plastic surfaces considerably more scratch and abrasion resistant, they look almost as good as new in a car’s interior even after long and intensive use,” sums up Dr. Pohmer. “In this way, automakers can easily and cost-effectively create more added value for their interior parts.” Parts made of talc-filled polypropylene that has been modified with GENIOPLAST® Pellet S can already be found in several manufacturers’ car interiors. European – especially German – and South Korean car manufacturers are pioneers here. However, the silicone pellets are also creating interest in the US automotive industry.