Production of FRP components without release agents

Up to now, releasing components from moulds required release agents. The problem is that the residues of these agents left behind must then be removed, which is a costly affair. Now, there is an alternative - a specially coated release film that leaves no residues.

If you want to bake a cake, you have to grease the baking pan beforehand, otherwise the cake will stick to it. Making fibre reinforced plastic (FRP0 components is much the same: release agents are wiped or sprayed onto the surface of the mould so that the component can be taken out once it has been cured. However, this approach leaves behind residues of release agents on both the component and the mould.

Component surfaces must usually then be manually cleaned – a painstaking and potentially critical process, since removing too much material has a negative impact on component quality. Moulds, too, must be cleaned regularly – but the downtime entails a not insignificant price.

Now, the Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM, Bremen, have developed a release film that renders these cleaning tasks. ''Our film can be applied to structures of all kinds and makes it easy to release components from molds,'' says Dr Matthias Ott, project manager in the plasma technology and surfaces PLATO section. ''It features a 0.3 micrometer thick plasma-polymer release layer that leaves no residues on the surface of the component.''

This coating on the film is based on development work conducted at the IFAM on producing non-stick component moulds using a low-pressure plasma process. First, the mould to be coated is placed in a plasma reactor and atmospheric pressure is reduced to one 10,000th. Next, layering gases are fed into the reactor and a plasma is ignited. Molecules containing silicon or carbon that are injected into the plasma are deposited as a thin layer. Since the molecules are highly reactive, they bond very well with the mould.

But there's a snag - plasma reactors are at best five cubic meters in volume, which means only relatively small moulds can be coated. So the researchers in Bremen, together with experts from Fraunhofer IFAM's 'project group joining and assembly FFM' in Stade, decided to strike out in a new direction.