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New TPU material for rotational sintering of decorative skins

Published on 2007-06-21. Author : SpecialChem

Leverkusen -- Rotational sintering is a widely-used process for making decorative skins for car dashboards and door panels. Desmopan® DP 3790AP from Bayer MaterialScience AG is a new aromatic thermoplastic polyurethane (TPU) formulated for this very technology. It is the material of choice not only for molded skins, which are coated by rotational sintering, but also for a new in-mold coating (IMC) slush molding process for decorative skins developed by international system supplier Intier Automotive Interiors, a member of the Magna International family. "Our TPU is superior to other decorative skin materials because of its combination of characteristics. It's plasticizer- and halogen-free, and because it remains flexible at low temperatures it doesn't become brittle in the cold, which is crucial to the safe functioning of the airbag. Unlike with a conventional spray process, you can use a ready-made plastic, which means much less work for the processor," explains Jürgen Hättig, an expert in automotive applications for TPU at Bayer MaterialScience.

Flexible at low temperatures, plasticizer-free and showing good adhesion to polyurethane foam and coatings
Desmopan® DP 3790AP is plasticizer- and halogen-free, and because it remains flexible at low temperatures it doesn’t become brittle in the cold, which is crucial to the safe functioning of airbags.

Intier's new IMC slush process makes it possible to manufacture ready-coated decorative skins in a single step. The process involves coating and heating the cavity of the molded skin tool and then connecting it to a box with the TPU powder. As this unit is rotated, some of the powder gels on the coating to form a skin. After cooling and removal of the powder box, the coated skin can be removed. The process has already proved itself in volume production, for example during production of a large-scale slush skin for the dashboard of a top-of-the-range vehicle. Compared with polyurethane spray technology and conventional slush molding, it has the advantage that multicolored decorative skins are easier and more cost-effective to produce by simply laminating them in the tool. There is also no need for a separate coating unit, which means even more cost benefits. The coating used in the process is a lightfast aliphatic polyurethane system that can be pigmented in bright colors. This coating retains its flexibility over a wide temperature range and is responsible for the surface quality of the decorative skin in terms of gloss, feel and scratch resistance.

Desmopan® DP 3790AP exhibits excellent adhesion not just to this decorative coating but also to the polyurethane foams used to backfill the skins. This was demonstrated in peel tests using specimens that had been stored for 500 hours at 120 °C. The tear strength of the new TPU and its elasticity at low temperatures were confirmed in high-speed tear tests at -35 °C. The material can also be used for the concealed rip seam of airbags, integrated in the dashboard so as to be invisible. This can be accomplished with widely available technologies such as laser burning.

About Bayer MaterialScience:

With 2006 sales of 10.2 billion euros (continuing operations), Bayer MaterialScience is among the world's largest polymer companies. Business activities are focused on the manufacture of high-tech polymer materials and the development of innovative solutions for products used in many areas of daily life. The main segments served are the automotive, electrical and electronics, construction and the sports and leisure industries. At the end of 2006, Bayer MaterialScience had 30 production sites and employed approximately 14,900 people around the globe. Bayer MaterialScience is a Bayer Group company.

Forward-Looking Statements

This news release contains forward-looking statements based on current assumptions and forecasts made by Bayer Group management. Various known and unknown risks, uncertainties and other factors could lead to material differences between the actual future results, financial situation, development or performance of the company and the estimates given here. These factors include those discussed in our public reports filed with the Frankfurt Stock Exchange and with the U.S. Securities and Exchange Commission (including our Form 20-F). The company assumes no liability whatsoever to update these forward-looking statements or to conform them to future events or developments.

Source: Bayer MaterialScience

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