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The New Building Blocks of “Green” Coating Technology

Published on 2010-01-07. Author : SpecialChem

LEVERKUSEN -- A new generation of cosolvent-free polyurethane dispersions from Bayer MaterialScience is further improving the performance of waterborne environmentally friendly two-component polyurethane coatings for various substrates. The coating films made using Bayhydrol® U dispersions display a wide spectrum of properties, ranging from hard through to flexible and a pleasant velvety soft feel. During a presentation at the recent European Coatings Conference on aqueous clear coats in Berlin, Bayer MaterialScience coating raw materials expert Dr. Martin Melchiors explained: "The new polyurethane polyols contain no n-methyl-2-pyrrolidone or any other cosolvents. They offer considerable potential in the formulation of waterborne two-component polyurethane coatings and are superior in many ways to the polyacrylate dispersions that have been most commonly used up till now."

Coatings based on Bayhydrol® U XP 2750 are hard, yet elastic - even in cold conditions - and are also extremely scratch-resistant. Developers from Bayer MaterialScience achieved this range of properties by incorporating self-healing segments into the polymer. As a result, the coating is able to realign itself after being scratched. In addition, coatings based on Bayhydrol® U XP 2750 have a high-gloss finish, are weather-stable and demonstrate a very high resistance to chemicals. The dispersion is ideal for clear coats and topcoats applied to metal and plastic substrates.

The strengths of the aqueous binder Bayhydrol® U XP 2755 really come into their own in two-component polyurethane systems for industrial wood and furniture coatings. As this highly reactive dispersion produces coatings that dry very rapidly, the coated parts can be stacked or used extremely quickly. Despite the product's quick-drying properties, the low minimum film-forming temperature of Bayhydrol® U XP 2755 means it can be used to produce coatings with an extremely low cosolvent content. These films are distinguished by their high level of hardness and gloss, excellent grain accentuation on the wood surface, good mechanical strength and resistance to chemicals. As it boasts a pot life of over six hours, the coating offers additional advantages when it comes to processing.

Bayhydrol® U XP 2757 was developed specifically for waterborne soft feel and "comfort" coatings. For example, these types of coating can transform "cold" plastics into surfaces that have a soft, warm and pleasant feel. Compared to an earlier generation of NMP-free polyurethane dispersions, Bayhydrol® U XP 2757 has seen the experts from Bayer MaterialScience achieve considerable improvements in the coating's resistance to chemicals. The new cosolvent-free dispersion is also suitable for wood and furniture coatings, an area of application that still represents new ground for soft feel coatings. This gives the wooden surface a pleasantly dry, natural feel that is barely distinguishable from that of uncoated wood. However, unlike untreated wood, these coated surfaces are water-repellent and resistant to any discoloration that could be caused by coffee or red wine, for example.

About Bayer MaterialScience:

With 2008 sales of EUR 9.7 billion, 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 2008, Bayer MaterialScience had 30 production sites and employed approximately 15,100 people around the globe. Bayer MaterialScience is a Bayer Group company.

Source: Bayer MaterialScience

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