Protect CFRP and GFRP effectively

Composite components are often exposed to harsh environmental influences. The right coating protects them effectively and helps them to last longer. A leading coatings manufacturer offers comprehensive solutions for the specific coating requirements of modern composites with its portfolio.

Whether seat shells, vehicle add-on parts, power distribution boxes or rotor blades - the possible applications of glass fiber and carbon reinforced plastics (GRP and CFRP) are extremely diverse. The reason for this lies in the numerous advantages offered by these materials. First and foremost, they are lightweight, but they are also extremely durable and resistant to water, cold and heat, and can also be molded into almost any shape. In order to ensure a long service life for components made of these materials, as well as to meet the requirements of the respective applications, a coordinated surface treatment is also necessary here. FreiLacke, a paint manufacturer based in the Black Forest, is one of the companies offering a wide range of coating materials for the surfaces of GRP and CFRP components. The family-owned company is already in its third generation and develops customized coating solutions with 600 employees at its site in Döggingen/Black Forest. For example, for wind turbines, one of the target industries: Here, for example, the leading edges of wind turbine rotor blades require special protection. The aerodynamic profile of their leading edges plays an important role in the efficiency of the wind turbine. They rotate at top speeds of 300 kilometers per hour or more. Their leading edges in particular are very exposed to erosion when used for power generation. This is significantly intensified and accelerated by environmental influences such as rain, snow, hail, sand, UV radiation and strong temperature and humidity fluctuations. In the case of offshore installations, the humidity and salt content of the sea air additionally increase the already very high stress. A high-performance edge protection coating, also called Leading Edge Protection (LEP), is therefore essential for smooth operation.

Coating solutions for durable wind turbines

FreiLacke's portfolio includes a wide range of coating solutions for various composite materials. These range from color pastes, putties and fillers to gelcoats and TopCoats. For customers in the wind energy sector, the coatings specialist has already developed several systems for the protective coating of rotor blades. "These only work well if they are specifically adapted to the substrate or to the coating materials underneath," explains Heiko Blattert, Development Manager PG Composites at FreiLacke. That is why his company offers a complete product range for coating rotor blades, all from a single source. FreiLacke also has tried-and-tested system structures in its range for the concrete tower production of wind turbines.These systems can also be transferred to other industrial concrete coating applications and are also already being used successfully there.

Inmold coating with gelcoats

Gelcoats and TopCoats are available in both brush and spray quality based on PU/PUR or unsaturated polyester resins (UP). Both are color-imparting coatings that are applied directly into the molds or dies and permanently seal the molded parts against moisture, UV radiation or pressure damage. After a component has been manufactured and demolded, it is already finished with a coating. Comparing PU/ PUR coatings with UP materials, the light and weather fastness of the former is significantly higher. FreiLacke was able to significantly reduce the styrene content in UP gelcoats. This substance is considered hazardous to health and the environment. "Using an alternative monomer, we have produced a styrene-reduced gelcoat that even achieves better results in terms of weather resistance and shelf life than conventional systems," reports development manager Blattert. Environmental protection has always been a key concern for FreiLacke. The company is committed to developing environmentally friendly products, reducing emissions, packaging materials and waste, and using resources sparingly.

Finished coating after pressing

The manufacturer has in-depth coating expertise not only for conventional composites. It also has solutions ready for sheet molding compound (SMC), i.e. plate-like, dough-like pressed compounds made from thermosetting reactive resins and glass fibers. This is a one-step manufacturing process during which electrostatically charged powder coating based on UP resins is applied to the hot mold. During hot pressing, the powder coating forms a chemical bond with the material that is scratch-resistant and highly resistant to chemicals, graffiti and UV radiation. This is particularly advantageous for parts that are used outdoors. The cycle time is only extended by the duration of the powder coating application and is around one minute, depending on the component. After pressing, the part is completely coated and is demolded. The typical fiber marking is completely leveled out by the Powder in Mold Coating (PIMC) process described, giving the parts a highly resistant and very homogeneous surface. In terms of color, PIMC offers a wide spectrum, as almost all RAL colors can be used. The material is free of solvents, hazardous substances or carcinogenic raw materials. "As an alternative to this, we have developed a liquid coating system that can be injected into the closed press mold during component manufacture," explains Blattert. This coating system has very short pressing times as well as very high resistances in terms of light and weather fastness. The component can either be "molded" or simply painted afterwards. This enables applications on automotive outer skin, for example.

Novel CM powder for component production

In addition to its wide range of coating materials for CFRP and GFRP surfaces, FreiLacke has recently started offering components for the manufacture of these components. Developing new solutions is easy for the company because of its expertise, says Heiko Blattert: "As a coatings manufacturer, we have all the raw materials on site from which we can develop new solutions." These new components include, for example, the novel CM Powder technology. This is a composite powder resin system that differs from conventional resin systems for composite plastics thanks to a special two-step principle. It can be completely melted without starting the curing process. This enables processing into so-called PrePregs with complete impregnation. The powder resin system contains no declarable ingredients and is completely free of solvents and harmful, carcinogenic substances, which greatly simplifies its storage and transport. It is available in different colors and reaction rates and offers high compatibility in the bonding of fibers, fillers, inserts and core materials. The new CM powder resins are used, for example, on the rotor blades of wind turbines. Here they offer a particular advantage, because they allow the blades to be manufactured in a single piece. The previous bonding of two individual parts is no longer necessary - and thus also a critical potential breaking point.

Developing solutions together with customers

With the development of the CM powder resins, FreiLacke has gone one step further in terms of advice and service for customers. This is because with the CM powder resins, customers not only receive the materials directly on request, but also comprehensive advice during the project planning and production of the components. Numerous companies, especially from the automotive and commercial vehicle industries, mechanical engineering, general industry and the construction sector, are already using FreiLacke products in the composites sector, the company reports. The cornerstone of this success is intensive cooperation with customers, says Heiko Blattert. "Since the founding days, we have been convinced that true service quality is only possible when problems and tasks are viewed through the eyes of the customer and are thus truly understood. We accompany our customers not only up to series production, but beyond the complete cycle."

Emil Frei GmbH & Co. KG www.freilacke.de