Huntsman Advanced Materials’ stand at Jec Europe 2014 highlighted what it describes as the improved design freedom its high performance chemistries are enabling in the latest composites concepts. Projects including structural composite parts on the BMW i series of electric vehicles, composite bonders on a prototype racing vehicle’s rear spoiler, and prepreg components on a Richard Mille luxury watch, illustrated the spectrum of applications that were on display.
Epoxy in automotive volume manufacturing
Epoxy composites are already in use in structural applications on luxury automotive brands; Huntsman says they are now ready for volume production of vehicle parts. The company is meeting demands for faster processing and reduced production cycles with the development of epoxy resin systems for high pressure resin transfer moulding (HP-RTM) and compression moulding. HP-RTM is preferable for the efficient production of highly complex parts, while compression moulding enables much faster output of low-complexity pieces.
Huntsman maintains that it is the first supplier to have produced epoxy resin systems that are certified as suitable for structural parts’ volume production. Its latest system – Araldite LY 3585/Aradur 3475 – is said to allow parts production in 5 and 3min respectively in HP-RTM and compression moulding, with a 1min latency at 110°C. This is 30% faster than first generation HP-RTM. Computer simulation capabilities at its laboratories in Basel, Switzerland, have enabled the company to develop fast and flexible epoxy systems with advanced properties for the automotive sector.
The company’s materials are already in use on the Mercedes SLR and BMW Z1, and are involved in projects for Lamborghini and McLaren. Stephan Costantino, Huntsman’s Technical Support Applications & Processes Team Leader, gave a presentation on ‘Fast and cost efficient solutions for automotive mass production’, which will highlight short cure cycle times enabled by Araldite resin systems for compression moulding and HP-RTM.
Araldite FST 40002/40003 is a new, high-performance RTM and infusion processing solution for interior aerostructures. The system is claimed to combine inherent FST properties with high quality, user-friendly composite processing methods. Araldite FST 40002/40003 is an ‘unfilled’ system which, according to Huntsman, provides good matrix mechanical properties and high fibre volume capabilities, and meets the aerospace industry’s requirements for further weight savings, while improving composite quality, eliminating intensive part production post-operations and improving the working environment. It meets FAR 25.853 vertical burn, smoke and toxicity specifications for both carbon and glass fibre in all thickness configurations.
Low weight, high strength
Structural adhesives facilitate high strength and stiffness on a variety of substrates as well as reducing stresses and improving chemical and temperature resistance. Araldite 2048 – a new methacrylate adhesive – was on the stand. Huntsman asserts that it shows some of the highest lap shear strengths available (24MPa on aluminium) and high elongation, as well as good chemical resistance, low ionic content, ease of application, high impact resistance, and elasticity at subfreezing temperatures. Araldite 2048 has been used with Araldite 2031 epoxy adhesive on the rear spoiler of a prototype sports car, which was on display. The application also demonstrated Araldite 2048’s capabilities in bonding aluminiums without surface preparation.
Tactix 742 tri-functional, TGHPM type epoxy resin, is said to offer a high glass transition temperature resistance, compared to similar epoxy resins. It can also be processed into prepreg formulations designed for high temperature applications. Huntsman says that Araldite MY 0816 can increase toughness without sacrificing thermal resistance. Aradur 1167, a latent accelerator recommended for dicy-based adhesives and composites applications, shows good latency up to 80°C and similar reactivity as a urea accelerator at 120°C and above.