Henkel automotive molding process uses polyurethane in RTM

Henkel has combined its new low-viscosity, fast-cure Loctite MAX 3 polyurethane resin with KraussMaffei's high-pressure resin transfer molding process to produce automotive parts quickly and paint-ready.

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Henkel (Rocky Hill, Conn., USA) reported on Sept. 19 that through the development of its new polyurethane matrix resin, Loctite MAX 3, the company has taken a further step toward fully automated series production of composite components for the automotive industry.

In collaboration with KraussMaffei (Munich, Germany), Henkel has developed a process for the manufacture of components based on glass or carbon fiber and high-­pressure RTM (HP­RTM) technology that creates a surface quality good enough for automobile exteriors. The process was developed and fine-tuned using a model of the light, high­-strength carbon fiber roof segment of the Roding (Roding, Germany) Roadster R1.

Loctite MAX 3,  is a three-­component polyurethane­-based matrix resin system that contains not only resin and hardener, but also a high-­performance release agent. This polyurethane-based matrix resin technology from Henkel is characterized by significantly faster curing compared to the epoxy resins usually used for RTM. Due to its low viscosity, Henkel says the resin penetrates the fiber more easily and with less disruption, giving rise to faster injection times and shorter cycle times in series production. Henkel also says the toughness of Loctite MAX 3 also facilitates achievement of an optimized component structure.

Henkel has likewise improved the temperature resistance of the PUR resin, reportedly taking Loctite MAX 3 to a level comparable with that of epoxy resins. High temperature resistance means that fiber­-reinforced composites can be demolded more quickly. With the internal release agent ensuring easy detachment of the component from the mold, the resultant surface is of sufficiently high quality to allow immediate painting and bonding. This accelerates the production process and enables manufacture of external and visible components of outstanding surface quality.

“With Loctite MAX 3, we now have a matrix resin system that further increases the feasibility and attractiveness of manufacturing automotive parts from composite materials,” says Frank Deutschla╠łnder, global market manager automotive at Henkel AG & Co. KGaA. “Working closely with KraussMaffei, we have optimized the properties of our resin so that both painted coatings and adhesives can be applied to the resultant composite surface without the need for any pretreatment.” With the adhesives portfolio from Henkel, this gives rise to a complete system solution enabling the manufacture and integration of composite components in automobiles.