Resin developments speed up the automotive production process

Paul Boughton

Andreas Moser looks at the future of the automotive industry and the latest composite materials technologies.

It is difficult for automotive industry at the moment, but the increasing focus across the world on the environment and better ways of bringing down costs presents us with opportunities. For example, in May President Obama made a breakthrough statement when he announced new fuel economy and new greenhouse gas emission standards for vehicles whereby they have to be 30 per cent cleaner and more fuel efficient by 2016. This is an opportunity where we can offer new technology in areas such as fuel cells and new composite materials.

And we are very close to seeing fuel cells becoming a reality. Hunstman Advanced Materials recently won, in conjunction with GrafTech International Holdings Inc, the JEC Innovation Award for a new technology to produce bipolar plates for fuel cells. The resin system developed for this process is now commercially available, another system based on benzoxazine will be available end 2009/early 2010.

Every major automotive manufacturer in the world is considering how best to utilise fuel cell technology to reduce carbon dioxide emissions and the reliance on fossil fuels, making the fuel cell component market a potential boom market.

Since the conversion of fuel to energy takes place via an electrochemical process, the process is much cleaner, quieter and up to three times more efficient than burning fuel and without CO2 emissions. The fuel cell's bipolar plates have superior corrosion resistance, lower contact resistance, higher thermal conductivity and a longer operating life at higher temperatures.

Our automotive fuel cell resin is based on benzoxazine which is suitable for high temperature PEM fuel cells. The resin which operates at a continuous temperature of 120°C has a phenolic-like backbone which gives it very good flame retardant properties together with excellent glass transition temperatures and mechanical properties. In particular there is a very high modulus, low water absorption and near zero shrinkage as well as good electrical properties.

A key driver of our development programme is to look for innovative ways that will speed up the production process of high performance composite parts while keeping the costs down. We have a dedicated research and technology team who is working on chemical formulations that will optimise cure cycles and on technologies that will support manufacturing processes so that composite materials are produced which are suited to large scale, fast and cost effective production. This is what the automotive industry wants from composite materials in their new model designs.

Every car manufacturer is looking for new materials that will enable them to make lighter weight cars with improved safety features at a lower cost. We have developed a new highly flexible composite, Araldite HFC with outstanding flexibility and strength that will not shatter in an accident which will cut the cost of car panel production. Last year it won two major awards at JEC Asia and Materialica, scoring best marks in the materials category for its outstanding flexibility and mechanical characteristics.

As a result of a thermosetting resin system, Araldite HFC has similar material characteristics to elastomers - excellent impact, abrasion and tear resistance with good elongation and tensile resistance - but is very different in terms of material and production time costs. Only a few consumable materials are required - resin and fibre - and, most importantly, just a single shell mould is required for component production. As opposed to elastomers, where it is difficult to incorporate fabric re-inforcement, and the processing is complex and expensive, the processing of low viscosity Araldite Highly Flexible Composite is simple.

Standard, well-established direct composite production processes, such as wet-lay up and infusion, can be used to produce parts from a single shell mould quickly and cost effectively. The parts can then be cured for 24 hours at room temperature or in an oven for 1 hour at 60°C and even faster at higher temperatures.

New generation toughened high-end Araldite NanoTech composite RTM composite material is based on a patented new nanotechnology concept which significantly improves fracture resistance without affecting vital physical properties such as flexural modulus, temperature resistance and viscosity to outperform standard resins.

The technology relies on the use of specific, dispersed organic nano-particles which exhibit outstanding toughening effects when incorporated in Araldite resins. The result is a tough, stiff material which is able to withstand shock without developing micro cracks making it ideal for high stress and impact exposed parts.

Also we have introduced RenShapeSL7820 which is the first material to produce solid black parts which require no additional painting. This saves manufacturers the cost and time of the extra process needed to paint SL models black - a colour that is frequently used for automotive prototype models and parts.

A sheet moulding compound/bulk moulding compound (SMC/BMC) is what the automotive industry wants from composite materials in their new model designs. As an example, in this area Huntsman is working on resin formulations for producing epoxy SMC/BMC to fill the existing gap between current polyester technology and long fibre reinforced epoxy composites with the aim of large scale production, with the advantage of lowest shrinkage, non-measurable emissions and highest mechanical performance.

There have been a number of new additions to the Araldite 2000 PLUS range of adhesives. One example is Araldite 2031 which is proving popular in the automotive industry in areas such as robotics. The automotive industry is the world's largest user of robotics and it needs adhesives that can cope with the stress of rotational speed of the tool, axial load to the tool and loading time.

Alfred Bilsing, CEO of Bilsing Automation and veteran of the automation industry said: "Stringent performance and reliability targets set by the rotating, clamping and swivel movements of robot parts on busy production lines had to be met. Wherever gripping and transportation becomes necessary in the automated process, there needs to be flexible tooling to minimise the design and development expense.

"Araldite 2031 was particularly impressive in its resistance to vibration allowing the movement of parts to move quickly and operate for a longer period of time without downturn."

As part of our dedication to automotive technical excellence, we are working with the Oreca racing team who this year have already taken a rostrum place in the Le Mans race series. Working with the Oreca team gives us the opportunity to test our materials beyond the limits of normal conditions. The technology transfer from racing cars to the consumer is very immediate. There is nowhere better to test new materials than in a racing car environment.

- Andreas Moser is with Huntsman Advanced Materials, Basel, Switzerland.

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