Fiber-reinforced plastics (FRP) convince with excellent properties such as high strength, low weight, stiffness and vibration damping. It is therefore not surprising that the market for these materials is growing continuously. Forecasts predict annual growth rates of up to double figures.
However, the special properties of FRP have so far been offset by relatively high production costs due to the complex manufacturing processes involved. Low raw material costs and low-cost production techniques are necessary to establish FRP in industrial series production on a large scale. These have to be designed in such a way that they enable the production of components of high and, above all, constant quality – require-ments which are not always easy to meet, especially for large components such as rotor blades of wind turbines. The DITF are developing resin systems that significantly reduce the previously high expenditure in process technology and enable cost-effective production.
Established systems with many disadvantages
In the processing of established thermoset two-component epoxy systems, some difficulties have to be handled to reach these objectives. For example, reaction accelerators are usually added to epoxies, which cause faster curing and thus a more cost-effective production. However, the resins in this form are difficult to store and transport: Due to the reaction accelerators they behave very reactive and therefore have to be cooled in a defined way with high equipment efforts until processing.
In established two-component epoxy systems, resin and hardener are mixed directly before processing. During processing, cross-linking takes place within a short period of time. There is a risk of pre-crosslinking, which starts before the textile layers are com-pletely penetrated by the resin. If this process is not perfectly coordinated, materials with non-infiltrated areas are obtained which are of inferior quality. Air inclusions can also occur during the mixing of resin and hardener, which can only be reduced by complex venting techniques of the epoxy system.