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Huntsman materials used in fulfilment of BMW LifeDrive concept

News International-French

17 Mar 2014

An epoxy resin system from Huntsman Advanced Materials has been specified by the BMW Group to manufacture structural composite parts on the new BMWi3 in volume production.

Huntsman’s materials are being used to produce the side frame as well other composite parts which are then assembled to form the BMWi3’s ‘life module’, also called the ‘passenger cell’.

BMW describes the innovative architecture of the BMWi3 as having two main elements. The aluminium Drive module – which incorporates the powertrain, chassis, battery, and structural crash functions – and the Life module or passenger cell, made from carbon fiber-reinforced plastic (CFRP).

The LifeDrive concept and use of CFRP allows production time to be cut by half compared to those required for an equivalent car built along conventional lines. The process is less investment-intensive as the high costs required for a conventional press shop and paintshop are no longer an issue and the Life and Drive modules can be manufactured alongside one another.

The use of CFRP on the scale required for the BMW i models is without parallel in the automotive industry worldwide and the BMW Group has also assumed a leading role in this area.

Structural body components on the i3 are being manufactured using high pressure RTM (HP-RTM) – a processing method now recognised as a key technology for large-scale production and excellent component properties.

The process involves making 3D dry carbon stack preforms using Araldite® LT 3366 as a binder powdered on the surface of the reinforcements. This helps to maintain correct fibre alignment and geometry during automated manipulation and positioning of the dry preform into the mold.

Huntsman’s epoxy RTM system Araldite LY 3585 / Hardener XB 3458 is then injected at high pressure into the mold. The system’s low viscosity plays an important role in the entire process, from the dosing and mixing right through to impregnation and good fibre wet-out in the mold.

Araldite LY 3585 / Hardener XB 3458 is fast reacting and can cure in just five minutes at 100°C. It enables BMW to produce finished parts in a very quick and cost-effective way.

The improved economy and productivity delivered by this fast Araldite resin system enables the automotive industry to produce large CFRP composite components as a viable commercial proposition for the first time.

Offering good thermomechanical performance, including a high elongation at break, the properties of this Araldite RTM system are particularly beneficial for automotive structural parts and requirements to meet crash test criterion.

Meeting increasing demand for reduced production cycles with epoxy resin systems for HP-RTM and compression molding processing methods, Huntsman is also the first supplier to offer resins that are qualified for the mass production of structural parts.

Huntsman’s materials will also be used on the second model in the ‘i’ line-up of plug-in cars from BMW when the larger i8 sports coupe goes into production this year.