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Bayer Introduces 2K-PUR for Wood

Published on 2003-07-10. Author : SpecialChem

With the binder Bayhydrol® XP 2427 and the hardener Bayhydur® XP 2487, Bayer Polymers, a division of Bayer AG, has developed new raw materials for the formulation of pigmented, waterborne two-component polyurethane (2K-PUR) wood coatings which are as good or better than the established solvent-based systems. Such environmentally friendly wood coatings have not previously been able to establish themselves on the market because their resistance to household chemicals and their mechanical strength were insufficient. Waterborne PUR coatings systems have gained large market shares in a number of other applications thanks to their low VOC emissions.

"With Bayhydrol® XP 2427 and Bayhydur® XP 2487, it is now possible for the first time to formulate waterborne, pigmented coatings which meet the most stringent quality requirements of the furniture manufacturers," says Dr. Christoph Irle of Bayer Polymers. Coatings formulated with the new raw materials satisfy the requirements of EN 12 720 (formerly DIN 68 861-1b).

They exhibit a resistance to scratching and abrasion similar to that of coatings formulated with Desmophen® A 450 and Desmodur® N 75 - the solvent-based reference standard for lightfast PUR coatings. Most importantly, they are at least as resistant as the reference to the staining effects of common household chemicals: In tests, no changes to the coating were observed after either a five hour "bath" in red wine or six hours of contact with coffee. Likewise, neither cleansers nor ammonia left any marks after one hour of exposure.

Because coatings formulated with Bayhydrol® XP 2427 and Bayhydur® XP 2487 are hand miscible, end users can apply them without problems. At room temperature, they dry within 16 hours; at 50 °C, wood can be stacked just two hours after application of the coating. The VOC content of typical formulations is less than 250 grams per liter.

During the development of Bayhydrol® XP 2427, the specialists at Bayer Polymers exploited the fact that a high concentration of hydroxyl ions in the outer sphere of the polymer binder particle has a positive effect on the chemical resistance of the resultant coating.

The hardener Bayhydur® XP 2487 is an aliphatic polyisocyanate which, due to an anionic group, is highly soluble in the water phase and also has a relatively large number of sites available for crosslinking.

Information about polyurethane coatings, including detailed descriptions of sample applications, and contact information can be found on the Internet at www.bayercoatings.com.

Source: Bayer


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