Composites for cost-effective lightweight construction

Fiber composite materials are lightweight and highly robust. This combination of properties opens up a wide range of potential uses in various applications, including as an alternative to conventional materials such as metal and wood. Covestro is presenting material solutions and technologies for the automotive, electronics and construction sectors and for the generation of renewable energies at the JEC World composites trade fair from March 14 to 16, 2017 at stand no. L9 in hall 5A. The developments set out below are based on the company’s comprehensive product and process expertise for composites.

While searching for a matrix material with excellent UV, weather and chemical resistance, the company developed a new polyurethane system and pushed back previous boundaries. Named Desmocomp®, it is formulated from aliphatic isocyanates and is ideally suited to outdoor applications. Covestro is being declared a "Composite Champion" at the fair for this development, earning it one of the coveted JEC Innovation Awards.

Lightweight vehicle components
Desmocomp® can be processed extremely cost-efficiently, thanks primarily to its exceptionally long pot life and rapid curing, which also make the new matrix material perfect for use in outdoor applications. One current application example is the weather-resistant, glass fiber-reinforced composites that development partner Sortimo International GmbH recently presented in the form of components for prototypes of its "System Unit," a storage solution for light commercial vehicles.

Working with prominent partners from the automotive industry, Covestro has also developed another polyurethane matrix system that is part of the Baydur® series. The special advantage of this system is that the carbon fiber composites can absorb three times more energy than comparable resin systems. The material ensures extremely high-level occupant safety in the event of a collision.

The first prototypes received very positive reviews during material testing. Thanks to the modern high-pressure resin transfer molding (HP-RTM) process with cycle times of just a few minutes, production of the components is very efficient.

Prepregs for cost-effective lightweight construction
Thanks to a new Baydur® casting resin system, Covestro has become the first to successfully achieve industrial-scale production and processing of storage-stable polyurethane prepregs. They offer a cost-effective alternative to epoxy prepregs, as they produce components with comparable mechanical properties at significantly lower production costs.

In the first stage of a two-stage production process, glass fibers are impregnated with the reactive resin, conditioned thermally, transitioned to a stable state in which they are not fully reacted and wound onto rollers with separating foil. In the second stage, they are taken out of storage and used to produce the component itself. Other advantages over epoxy resins include more consistent component quality and more cost-effective, energy-efficient production. The technology is also to be made adapted for use in other applications in the future.

High-tech material for consumer electronics
Covestro has developed a completely new composite technology for the efficient production of casing parts for mobile electronic devices. Based on polycarbonates and carbon fibers, the new technology meets current demands for particularly thin, lightweight and yet robust parts. The company uses this system to produce continuous fiber-reinforced unidirectional tapes and sheets for further processing by its customers.  

The thermoplastic composites (CFRTP) come into their own when used in consumer electronics products. They provide the best strength-to-weight ratio of all standard composites on the market and are suitable for cost-effective and flexible mass production. Two of the reasons for this are short cycle times - with minimal manual work - and high yields.

RocTool, a specialist in high speed heat and cool molding solutions, will give a live demonstration of their new Induction Dual Heating (IDH) technology by showing the production of a laptop cover with a selection of thermoplastic materials including CFRTP composites from Covestro. The demonstration can be seen at RocTool’s booth (hall 6, booth no. A32). The company presented their new IDH molding process for the first time at K 2016 trade fair, together with Flex, a leading electronic manufacturer, and other partners such as Covestro.

More speed in pultrusion
Pultrusion is a unique technology that is suitable for continuously manufacturing fiber-reinforced plastics. It therefore plays an important role for Covestro composites. Thanks to its high productivity and outstanding product characteristics, it supports a diverse range of applications, particularly in the construction industry. One current example is window frame applications, where the high strength plus the heat and noise-absorbing effects of the polyurethane composites are particularly beneficial.

Covestro is currently working with plant manufacturer KraussMaffei on further developing the pultrusion process. The aim is to use cutting-edge plant engineering to boost productivity in the manufacture of straight and curved profiles. This also involves developing new injection boxes. KraussMaffei is exhibiting the initial results at Booth B 38 in Pavilion 6 at JEC World, where it will be presenting applications from the construction and wind power sector.

Cost-effective production of rotor blades
Speaking of wind power: Besides lightweight vehicle concepts, power generation based on renewables is another key part of Covestro’s sustainability concept. The need for more cost-effective ways to produce wind turbines is greater than ever if we are to make more intensive use of wind energy.

Covestro has developed a special polyurethane infusion resin for the manufacture of rotor blades. In combination with reinforcing glass fibers from the company’s partner SAERTEX® and an efficient production process from HÜBERS, the resin enables short cycle times. This gives manufacturers a clear cost advantage. After all, rotor blades account for around a quarter of the total cost of new wind turbines. The resin also exhibits very good mechanical properties.

Optimal effect of glass fibers
To fully exploit their ability to reinforce plastics, glass fibers are coated with sizing immediately after their manufacture. This protects the glass fibers from mechanical damage that could occur during subsequent processing. However, the real purpose of the sizing becomes evident in glass fiber-reinforced plastic composites, where it is partially responsible for the mechanical bond between the plastic matrix and the fiber surface, and therefore for the strength of the composites.

Waterborne polyurethane dispersions from the Baybond® line of Covestro are used as film formers in glass and carbon fiber sizings for thermoplastic composite materials. The dispersions boast very good film formation, elasticity, adhesion and yellowing stability and can withstand high levels of mechanical stress. What’s more, some Baybond® products also satisfy European Regulation EU 10/2011 for plastics that come into contact with foods.

Besides continuously expanding its product portfolio for thermoplastic applications, Covestro is also currently working to extend the Baybond® family by adding products for thermosetting applications.

For more information about Covestro, please visit www.covestro.com.