May 1 2008
Natural materials such as sugar, glycerin and sorbitol have been used for many years now in the production of polyols -one of the two basic components in polyurethanes alongside isocyanates. However, developers are currently working on a growing number of natural oil polyols (NOPs) that contain vegetable oils as well as these other raw materials.
Experts believe that these polyols, which contain a higher proportion of renewable raw materials, will continue to grow in importance as they are regarded as more sustainable than conventional materials based on fossil fuels, and demand for such "green" products is increasing steadily. However, the NOPs currently available on the market also have a number of drawbacks that limit the extent to which they can be used. Bayer MaterialScience has now developed an innovative production technology that overcomes many of these challenges. The process is designed for the production of NOPs that are to be used in rigid polyurethane foams and the company has filed a patent application accordingly. Of all materials on the market, polyurethane rigid foams offer the best thermal insulation properties, and they are used extensively throughout the world for efficiently insulating buildings, refrigerators and pipelines.
"The new process uses an ingenious method to merge two different chemical reactions in a single step," explains Dr. Klaus Lorenz, senior principle scientist with the Polyether Process Development at Bayer MaterialScience.
"By combining the processes of alkoxylation and transesterification, we can produce polyols with a high content of vegetable oil components and yet deliver the same range of properties and the structural diversity of conventional polyols." When using various popular blowing agents, rigid foams based on the NOPs produced with this new technology exhibit properties that not only match, but in some cases even surpass those of conventional products. It is the company's long-established experience and comprehensive know-how in the field of polyurethane systems development that have enabled Bayer MaterialScience to meet such specific customer requirements.
Exceptional compatibility with conventional polyols also means that the quantity of NOPs specified in formulations can be increased. This in turn enables rigid foams to easily satisfy the U.S. government procurement guideline that accords preferential treatment to products made from renewable materials, as opposed to those based on petrochemical raw materials. This guideline is based on a proposal from the U.S. Department of Agriculture (USDA), which states that when public institutions are seeking to procure products, including construction materials, these materials must contain a minimum content of renewable raw materials in order to be classed as "Biopreferred." In the case of thermal insulation for wall construction, a rigid foam (spray foam or foam board) is required to contain at least eight percent biobased content to attain this classification. While polyether polyols based on sugar may contain up to about 30 percent renewable raw materials, this new technology enables the production of NOPs containing between 40 and 70 percent renewable raw materials. Rigid foams made with these NOPs may contain in the range of 10-15 percent biobased content, thus exceeding significantly the threshold to be classed as "Biopreferred."
"The development of this new production technology gives us a significant advantage over our competitors in the key market for renewable raw materials used in polyurethane manufacture," explains Dr. Peter Seifert of Global Polyether Product Management. "The new process enables us to formulate rigid foams with a significantly higher renewable raw material content, which can help protect our environment not only by cutting energy consumption, but also through the careful selection of raw materials."
Bayer MaterialScience showcased a range of promising applications that use the newly developed polyols at the K 2007 plastics fair. One example is a high-end refrigerator from Liebherr, the insulation layer of which is made from NOP-containing BaythermR rigid polyurethane foam. The device has achieved the exceptional energy efficiency rating of A+. In this instance, the content of renewable raw materials has been doubled in comparison with conventional polyurethane insulation systems. What's more, the processing and end properties of the new system are in no way inferior to those of the rigid foams already available on the market and in some respects even surpass them.
Formulation development aimed at incorporating NOP's is underway in the NAFTA region with focus on the construction applications of PUR / PIR rigid foams - laminated boardstock, spray foam and rigid bunstock. "We are encouraged that the NOP's which Bayer MaterialScience is developing will provide a good addition to our line of performance products," states William J. Nicola, head of applications development for Rigid Specialities Raw Materials of Bayer MaterialScience, LLC. "Our work in this area is targeted for initial implementation in the second half of 2008."
Posted April 30th,2008