Polyurethane Adhesives for Modern Structural Wood Construction
The current success of load-bearing wood construction wouldn’t exist without high-performance adhesives, however. Modern one-component polyurethane systems offer a number of decisive advantages for this application: they are applied directly from the drum, and there is no need to mix components prior to applying the adhesive, nor are there any pot lives to be considered. Odorless and formaldehyde- and solvent-free, the adhesives are also environmentally compatible. The production process is very economical, requiring less adhesive than other systems and allowing parts to be stably and permanently joined after a short press time.
Before they are introduced to the market, adhesives for engineered wood must be tested and certified. In Germany, the Materials Testing Institute (MPA) at the University of Stuttgart is responsible for testing and assessment. The MPA uses test methods derived from previous work with phenol-resorcinol and melamine-urea resins to determine adhesive strength, application properties and long-term durability of adhesives. The first one-component polyurethane adhesive certified in Germany for the manufacture of load-bearing wood components received general regulatory approval in 1994.
Purbond AG, Sempach Station, Switzerland, is the market and technology leader for one-component polyurethane (PU) adhesives for the manufacture of load-bearing wood elements. Bayer MaterialScience is the leading supplier of the isocyanate prepolymers used as raw materials for this application.
According to the MPA, Purbond and Bayer MaterialScience, the methods underpinning current standards do not give sufficient consideration to the outstanding properties of polyurethane adhesives. To obtain even more reliable test results and ensure the continued market success of polyurethane systems, the MPA and Bayer MaterialScience plan to develop test methods, with the support of Purbond, to improve predictions of long-term behavior. This work will incorporate the latest scientific findings, with the results of the fundamental and application-oriented projects to be used to improve existing standards.
About Bayer MaterialScienceWith 2006 sales of $10.2 billion (continuing operations), 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 2006, Bayer MaterialScience had 30 production sites and employed approximately 14,900 people around the globe. Bayer MaterialScience is a Bayer Group company.
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