AN INTEGRAL PART OF THE FORMULATION

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AN INTEGRAL PART OF THE FORMULATION
22 April 2005 - Bayer MaterialScience AG

Researchers at Bayer MaterialScience have developed a novel blocking agent for prepolymers used to flexibilize epoxy systems.

“After fulfilling its function, it is incorporated into the resulting polyurethane or polyamide network,” says Dr. Christoph Gürtler, one of the developers.

Conventional blocking agents, on the other hand, are split off or emit a substance.
The fact that one- or two-component polyurethane or epoxy systems containing Desmocap® LP MMC 3306 do not undergo a deblocking reaction is advantageous.

“Such systems can be used for the formulation of permanently flexible coatings whose properties are not altered over time by released substances,” says Dr. Thomas Stingl, an expert in the Coatings, Adhesives and Sealants Business Unit of Bayer MaterialScience. The coatings do not blister, even when applied in thick coats. And because LP MMC 3306 emits no volatile organic compounds (VOC), it is also environmentally friendly.

The new blocking agent offers another advantage with respect to VOC directives: Polyisocyanates or isocyanate prepolymers blocked with the product have a significantly lower viscosity than those converted to storage-stable adducts using conventional reagents. LP MMC 3306 can therefore be used to formulate low-solvent or even solvent-free coatings. Viscosity is approximately 23,000 mPas, substantially lower than the roughly 100,000 mPas of conventional systems.

Reactive polyurethanes blocked with LP MMC 2206 can be used to correct a known weakness of solvent-free, epoxy-based formulations – although low-VOC formulations of this type have many interesting properties, the epoxy resins used in them must have a low molecular weight. The resulting casting resins or coatings are therefore extremely brittle and tend to crack, making them unsuitable for most applications. Blistering may also occur. This can be overcome by adding blocked polyurethane prepolymers like LP MMC 3306. As the formulation cures, the prepolymers are incorporated into the epoxy-amine network via true chemical bonds, making the resin more flexible. LP MMC 3306 is very effective. In particular it shows a long-lasting effect.

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About: Bayer MaterialScience AG
Bayer Corporation, headquartered in Pittsburgh, is part of the worldwide Bayer Group, an international health care, nutrition and innovative materials group based in Leverkusen, Germany. Bayer employs 23,300 in North America with net North American sales of 8.8 billion euros in 2003. Bayer’s three operating business areas – HealthCare, CropScience and MaterialScience, improve people’s lives through a broad range of essential products that help diagnose and treat diseases, protect crops and advance automobile safety and durability.

Bayer MaterialScience AG is one of the world's largest producers of polymers and high-performance plastics. The main customers for Its innovative developments in coatings, adhesives, insulating materials and sealants, polycarbonates and polyurethanes are the automotive and construction industries, the electrical/electronics segment and manufacturers of sports and leisure goods, packaging, and medical devices.

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