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75 years on from its "invention", the success story of polyurethanes is far from over

News International-French

26 Apr 2012

In the beginning it was all about fibers. In 1937, Dr. Otto Bayer was looking for a new synthesis strategy for fibers. After the invention of nylon the demand for synthetic fibers as a substitute for natural silk quickly grew.

At that time Bayer, aged 35, was head of the Leverkusen-based central scientific laboratory of the German company then known as I.G. Farbenindustrie. He was not only interested in developing a new chemistry, but also wanted to establish a more efficient method of producing plastic that would involve a small number of simple by-products.


However, his subsequent "invention" of polyurethane (PU) chemistry - based on the reaction between diisocyanates and polyols - was not a runaway success from the start. Indeed, the idea of synthesizing plastics from isocyanates, which were known at the time to be highly reactive and therefore chemically unstable, seemed completely mad to his supervisors. Nonetheless, a patent application was submitted for the research findings on November 13, 1937 and German Imperial Patent (DRP) 728.981 became the "birth certificate" for polyurethane chemistry.

Contrary to initial hopes, the first experiments did not produce synthetic fibers - that would only come later on. The result was more of a foam with pores generated by the formation of a by-product, carbon dioxide. Otto Bayer's supervisors were still not particularly impressed and could not see the product amounting to anything more than "a substitute for Swiss cheese."

The 1940s - groundbreaking work for chemists and engineers
The inventor and his team would not be put off. In the years that followed, they expanded their focus beyond laboratory work to investigate where the foams, fibers and elastomers from the new plastic could be used. Quotes from the basic patents up to 1948 show that even then the researchers were demonstrating enormous creativity: "The porous lightweight materials are suitable as a support material in aircraft construction and shipbuilding, as an insulating material for heat, cold and noise, [...], for furnishings, tires, toys, house building, prosthetics, shoe soles and traction bandages."

But there were still major challenges to overcome before such products could be developed and launched on the market. The company would have to find ways of manufacturing the material on an industrial scale. That would not be possible without suitable process engineering, which led to close cooperation between the chemists and engineers. However, the first step was to establish a basis on which the subsequent process chain could be built. The most important task was to shift the chemical reaction - and therefore the actual production of polyurethanes - to the customer while also ensuring high quality standards for the end products.

The 1950s - ongoing development and market launches
The period shortly after the end of the war saw a major upsurge in the ongoing development of polyurethane chemistry and processing technology, application areas, markets and therefore capacities. In 1952, Bayer AG launched elastic flexible foam slabstock made of TDI (toluene diisocyanate) and polyester polyols on the market for the first time under the Moltopren® brand name. In the years that followed, polyethers, which significantly expanded the application options for polyurethanes, were also introduced to the market.

In 1955, Bayer registered the Desmopan® brand of thermoplastic polyurethanes (TPU): polyurethanes by their chemical origin, thermoplastics by their processing, these products opened up a whole new range of application options. From 1958, polyurethane coatings based on Desmodur® and Desmophen® (known as DD coatings for short) grew in popularity, becoming synonymous with high-performance repair coatings for cars, ships and aircraft.

The 1960s - rigid and flexible foams dominate the markets
The story of polyurethane reached a further milestone in 1960, when rigid foams with metallic top coats - known today as metal sandwich panels - were presented for the first time. Flexible foams became increasingly popular as materials for furniture and car seats, where they provided extra comfort and secure seating.


The 1960s also witnessed the first ever use of polyurethane integral skin foams in the manufacture of arm rests for automobiles. Products made from such materials exhibit a continuous and gradual transition from a smooth outer surface to a cellular core, similar to the way bones are structured. In the following year, the exceptionally high-performance elastomer Vulkollan® came into the world. To this day, the Bayer product still withstands even the toughest conditions in applications such as forklift truck tires.


The refrigeration industry first started using rigid polyurethane foam as a heat insulation material in 1962. This popular material delivers extremely efficient heat insulation, thus helping refrigerators to run cost-effectively, and so it is little wonder that it continues to dominate the refrigeration chain today. The first automobile with bodywork made entirely of plastic - the K´67 - caused a stir when it was presented at the 1967 plastics fair in Düsseldorf. The launch of the continuous lamination process in 1968, which enabled non-stop production of rigid foam blocks, paved the way for expanding the market launch of insulating panels for efficient thermal insulation in buildings.


In view of all these major developments, it is no wonder that the consumption of polyurethane also increased dramatically. During the "Swinging Sixties" alone, global production rose from 200,000 metric tons per year to more than a million metric tons. This decade also saw the entire range of polyurethane components come onto the market for the first time - from diisocyanates and polyols to catalysts, blowing agents and additives for a whole variety of purposes.


The 1970s - polyurethanes become part and parcel of day-to-day life
The two oil crises of the 1970s held back growth in the consumption of PUR, but not for long. Indeed, polyurethanes had already become an accepted material in many areas of life, from cars and construction to the food, fashion and health care industries. Even more important developments were launched on the market, too, thereby further expanding business opportunities. One example is foam cavity filling for automotive applications.


The introduction of reaction injection molding (RIM) technology in 1971 was another technical advance that could be put down to close collaboration between chemists and engineers. By injecting reactive polyurethane components into a highly pressurized mold, this process enables users to produce large molded parts in short cycle times and with reproducible, high-quality results. Today, large bodywork parts with surface areas of several square meters for use in agricultural machinery can be produced in a single operation.


The 1980s - innovative and sustainable ideas expand the material's position
This decade saw the focus shift toward customized polyurethane properties. One example would be car seats that were more comfortable and functional and used a combination of two different hardnesses. Thanks to the Bayfit® PUR system from Bayer and new multi mixing-head technology, upholstery such as this could now be produced in a single operation.

At the end of the 1980s, Bayhydrol® and Bayhydur® were launched as raw materials for waterborne and therefore low-solvent coatings. The introduction of flexible foams that could be manufactured without chlorofluorocarbons (CFCs) represented another sustainable development. CFCs are suspected to be harmful to the ozone layer. But polyurethanes also began to play a greater role in boosting safety standards for customers. In car interiors, for example, energy-absorption foams based on Bayfill® EA offered occupants greater protection from side impacts.

The 1990s - closer to the customer, improved service
The next decade brought the global expansion of polyurethanes to the fore. At the same time, companies such as Bayer developed a worldwide network of consulting, marketing and technical service centers to support customers and ensure they could rely on a flexible and fast supply chain.

A further milestone was the introduction of viscoelastic foams, which regain their original shape very gradually and offer greater comfort than conventional flexible foams. One of the key applications for this product is in mattresses that can help stop patients developing bedsores.

The 21st Century - the success story continues
With the development of the polyurethane spray systems Baypreg® and Multitec® at the start of the new Millennium Bayer MaterialScience opened the door to a new class of composite materials that combine low weight with high rigidity. They unlock a diverse range of applications in areas stretching from automobiles to bathtubs.

Global megatrends such as climate change are throwing down brand new challenges for heat insulation in buildings and the refrigeration chain and for lightweight vehicles that run on an efficient and resource-friendly basis. Bayer MaterialScience develops innovative solutions for these megatrends and is exhibiting a number of important new developments at UTECH 2012. These key innovations include a rigid foam system for the refrigeration chain that exhibits much improved insulating performance, and an even more lightweight material for manufacturing car parts. Completely new opportunities are also opening up for the resource-friendly production of polyurethane raw materials using the greenhouse gas CO2.

In other words, the signs are that the success story of polyurethanes is set to continue into the 21st Century.


About Bayer MaterialScience:
With 2011 sales of EUR 10.8 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 2011, Bayer MaterialScience had 30 production sites and employed approximately 14,800 people around the globe. Bayer MaterialScience is a Bayer Group company.

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