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Bayer MaterialScience Performs Extensive Tests In Collaboration With Major Manufacturers

Published on 2008-06-17. Author : SpecialChem

Pittsburgh, PA -- Bayer MaterialScience (BMS) worked together with adhesive manufacturers Dow Automotive, Henkel and Sika to determine which of the adhesive systems commonly used in automotive glazing are best suited for use with Makrolon AG 2677 polycarbonate (PC) resin, Makroblend DP1-7665 PC/PET resin and Bayblend T 95F PC/ABS alloy under various conditions. Together, BMS and the adhesive manufacturers performed wide-ranging tests with these thermoplastics.

"The results and know-how we obtained from the tests will help us optimize our service in customer projects for polycarbonate glazing components," says Peter Capellen, an expert in polycarbonate coating at BMS.

Today in car production it is customary to bond large transparent roof modules made of PC and PC blends to the vehicle's steel roof. PC and PC blends normally used as the frame materials have coefficients of thermal expansion that are more than five times higher than that of steel, which is an important consideration for car manufacturers. The choice of adhesive, the nature of the substrate and the position of the adhesive bead play a major role in minimizing the deformation of the bonded plastic part in both hot and cold conditions, and ensuring that no irregularities appear in and on the surface.

There are a variety of possibilities for bonding the transparent PC to the roof, depending essentially on the substrate to which the adhesive system is applied. It may be applied either to the plastic itself (uncoated) or to the scratch-resistant hard coat that protects the plastic from chemicals and weather. Depending on the adhesive system, pretreatment of the substrate with an adhesive primer can be beneficial in both cases.

The tests took into account all of the available combinations of substrates from BMS and the conventional coating systems that are used in practice for PC glazing in the automotive industry. The tests specimens were made of Makrolon AG 2677 PC resin, Makroblend DP1-7665 and Bayblend T 95F PC blends, both in an uncoated form and protected with the appropriate scratchproof coatings. The bonded joints were subjected to accelerated aging tests consistent with specifications identified by car manufacturers. The results of tensile shear tests carried out before and after aging provided valuable information on the correct choice of adhesive system.

"The tests showed that tailor-made adhesive systems are available for all of Bayer MaterialScience's glazing materials, whatever technology is used," says Capellen.

Based on these results, the adhesives will be subjected to further development in cooperation with the adhesive manufacturers and users such that the bonding systems will comply with future specifications.

BMS offers manufacturers of PC automotive glazing a full package that comprises not only the tailor-made materials but also a wide range of services along the entire process chain - from PC granules to the ready coated glazing. The company's expertise in materials selection, design and fabrication includes determining the best position of the adhesive bead for bonding a glazing element using special computer-aided engineering (CAE) tools, whereby simulation accounts for the elasticity of the adhesive at extreme temperatures. The technical support may also include rheological tests, assistance with mold design and part-testing. Experts are available to advise on the surface treatment of PC for items such as abrasion and weather-resistant coatings.

Bayer MaterialScience LLC is one of the leading producers of polymers and high-performance plastics in North America and is part of the global Bayer MaterialScience business with nearly 15,400 employees at 30 sites around the world and 2007 sales of 10.4 billion euros. 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, medical, and sports and leisure industries. Our inorganic basic chemicals unit produces chlorine and related essential products for the chemicals industry. Let us give life to your vision. Bayer MaterialScience -- Where VisionWorks.

Source: Bayer Corporation


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