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Bayer MaterialSciene: Bayhydur® - Crosslinking Experience and Progress

Published on 2009-04-02. Author : SpecialChem

LEVERKUSEN -- Over the last two decades, water-dispersible polyisocyanates have made a lasting contribution to the triumphant ascent of waterborne, two-component polyurethane coating systems. In addition to proven crosslinkers from its Bayhydur® range, Bayer MaterialScience AG, a pioneer in this field, is once again presenting innovative new developments to simplify application.

New on the market is Bayhydur® XP 2700, a ready-to-use supply form of Bayhydur® 305 in a low-odor solvent that is particularly well suited for glossy, clear coating films. The highly reactive crosslinker has a very low viscosity and can be blended with the polyol simply by manual stirring or shaking. It is particularly robust with respect to handling errors during application and thus optimally designed for the needs of manual application. Another new product, Bayhydur® XP 2759, is derived from isophorone diisocyanate (IPDI) and is available commercially as a 70 percent solution in methoxypropylacetate. In combination with HDI-based grades, it is ideally suited for the production of faster-drying coating formulations with high final hardness and an improved blister limit. With this property profile, the new crosslinker ideally rounds out the system toolbox comprising the Bayhydur® range.

A key challenge facing waterborne polyurethane coating technology is to create sufficiently stable emulsions of the water-immiscible polyisocyanates in polyol, which can Bayer MaterialScience at the European Coatings Show 2009 Bayhydur® - crosslinking experience and progress New hydrophilic polyisocyanates round out the system toolbox for waterborne polyurethane coating systems then be applied to the substrate. Modified polyisocyanates with a molecularly anchored emulsifier ideally satisfy this requirement. "The result is a perfect emulsion that can be reliably manufactured, is stable and free of the disadvantages, such as migration or clustering in the coating, that are associated with the use of external emulsifiers," says Dr. Christoph Irle, an expert for waterborne polyisocyanates at Bayer MaterialScience. Bayer MaterialScience has been applying this principle for decades to develop environment-friendly coating raw materials tailored to meet any requirements placed on the coatings. They are optimally tuned to the respective application technology and contain only a minimum of organic solvents, with a number of systems being completely solvent-free. Bayhydur® thus perfectly reflects the motto of Bayer MaterialScience's stand at this year's ECS: "Water is green."

Most products in the Bayhydur® range are derived from the fast crosslinking hexamethylene diisocyanate (HDI). The resulting mixtures with the polyol components represent the optimal compromise with respect to pot life and reactivity. This is equally true for the universal grades Bayhydur® 3100 and 304 as it is for the specialties. One such specialty is Bayhydur® XP 2547, which due to its low viscosity is particularly easy to incorporate even without the addition of solvents, or Bayhydur® XP 2655, which sets new standards with respect to chemical resistance.

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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