Evonik makes automotive clear coats more scratch-resistant

German firm Evonik Industries says it is paving the way for a new technology whose applications include automotive finishes that are more scratch-resistant than before. The speciality chemicals company has developed an industrial-scale method for producing silane-modified binders for automotive finishes. The advantage of these silane-modified binders: silane groups increase crosslinking density, making it possible to create automotive finishes that are flexible yet harder, leading to improved scratch resistance.

The basic concept behind the new technology was already known: modifying classic binders with silanes noticeably improves the binder properties. This also applies to the polyurethane binders typically used for automotive finishes. Up to now, however, production of silane-modified polyurethane binders has been so complex and expensive that these products have only been made on a small scale for applications such as high-performance adhesives. For more general uses and for large-scale applications such as automotive finishes, however, there simply has not been enough available. The new technology from Evonik stands to change all of that.

The breakthrough came when the speciality chemicals company developed its own manufacturing process for the silyl isocyanate IPMS, or (3-isocyanatopropyl) trimethoxysilane. It is the critical building block for producing silane-modified binders. Evonik has been producing IPMS in a new facility in Marl (Germany) since mid-2013. Dr. Ulrich Küsthardt, head of the Coatings & Additives Business Unit at Evonik, points out: “With the new facility, Evonik creates its access to IPMS and to a new group of customised, silane-modified binders.”

By using IPMS and selecting the right additional raw materials, Evonik can adapt coating binders to the needs of its customers. One of the first applications for the new IPMS binders is the thin clear coating—only about 40 micrometers thick—that serves as the glossy top layer of an automotive finish. In addition to improved scratch resistance, the new systems are just as resistant to chemicals and the elements as traditional two-component polyurethane coatings. Plus, silane-modified binders are completely compatible with two-component polyurethane coatings and significantly improve their properties. For car manufacturers, that means being able to use their usual production lines for applying coatings that contain the innovative binder. Selected automakers have already taken the first steps toward approving clear finishes that have been modified in this way.

The firm also aims to open up access to silane-modified binders for other applications, such as coatings for wood, plastics, metal, and high-tech adhesives. "The key criterion here is that the silane-crosslinked clear coats cure quickly enough at room temperature," it said.

(IMA)

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