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2-Component Polyurethane Coatings Exceed Industry Standards for Weatherability: Bayer MaterialScience Researchers Explore Factors Influencing Weathering Performance of Two-Component Polyurethane Topcoats

Published on 2008-02-18. Author : SpecialChem

Pittsburgh -- The power of polyurethane topcoats first debuted in the industrial maintenance and marine markets in the mid-1970s as part of a corrosion protection system. Polyurethane topcoats have evolved over the years into a versatile technology that can be formulated to create low VOC coatings and productivity enhancing coatings, as well as long-lasting, cost-effective coatings. However, recently there has been a call for ultra-high weathering performance topcoats for applications such as sports facilities, water tanks and bridges where coating systems are expected to provide aesthetic appeal along with corrosion protection.

In a quest to explore whether current weathering performance specifications for two-component polyurethane topcoats - such as SSPC Paint Specification No. 36 - go far enough in defining the highest level of polyurethane performance available for these demanding applications, Edward P. Squiller, director, Specialty Coatings and Kurt Best, senior scientist, both of Bayer MaterialScience (BMS) LLC, authored a paper: 2-Component Polyurethane Topcoats - Formulating Variables Affecting Weathering Performance. The authors discussed their paper at the recent 2008 Paint and Coatings Expo.

There are many potential variables in typical corrosion protection topcoat formulations that influence performance and application characteristics, as well as the cost structure of the coating. These variables include isocyanate index and resin selection, which play a major role in determining the weatherability of the final product.

In their paper, the authors compare some key formulating variables of aliphatic polyurethane topcoats and their resulting performance in an accelerated weathering study. Aliphatic polyisocyanates traditionally result in topcoats with much better outdoor weathering characteristics versus aromatic polyisocyanates, and are primarily used in outdoor topcoat applications in which gloss and color retention are required.

Through their research, the authors discovered that all of the polyurethane topcoats tested met the highest performance level specified by SSPC Paint Spec. #36 with regard to loss of gloss and yellowing, therefore concluding that the topcoats are capable of achieving a much higher performance standard. However, the authors caution against reading too much into just one accelerated test method relative to other important considerations.

"This topcoat weathering study focuses on just one element of the coating selection process for a corrosion protection coating application," said Squiller, who also noted that the coatings in the study have been submitted for South Florida weathering and will be presented in the future when the results become available. "One must also consider the application characteristics of the paint, as well as cost and corrosion performance as part of a multiple-coat system."

About Bayer MaterialScience LLC:

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 14,900 employees at 30 sites around the world and 2006 sales of 10.2 billion euros from continuing operations. Our innovative developments in coatings, adhesive and sealant raw materials, polycarbonates, polyurethanes and thermoplastic urethane elastomers enhance the design and functionality of products in a wide variety of markets, including the automotive, construction, electrical and electronics, household and medical industries, and the sports and leisure fields. 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.

About Bayer Corporation:

Bayer Corporation, headquartered in Pittsburgh, is a subsidiary of Bayer AG, an international health care, nutrition and innovative materials group based in Leverkusen, Germany. In North America, Bayer had 2006 net sales of 7.8 billion euros and employed 17,200 at year end. Bayer's three subgroups, Bayer HealthCare, Bayer CropScience and Bayer MaterialScience, improve people's lives through a broad range of essential products that help prevent and treat diseases; protect crops and enhance yields; and advance automobile safety and durability.

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. Th ese 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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