Plasmatreat's Openair-Plasma system provides MonoPan Composites, a composite honeycomb panel manufacturer, with a reliable, high-speed and low-cost dry pretreatment solution to achieve uniform wettability. #application

Plasmatreat's Openair-Plasma technology uses rotating nozzles (shown above) for fine cleaning, electrostatic discharge and surface activation. Plasma can ensure full surface wettability and significantly improve the bonding properties of the material surface. Image source: Plasmatreat

MonoPan Composites (formerly Wihag Composites in Thuringia, Germany) has been manufacturing ultra-lightweight polypropylene (PP) honeycomb sandwich panels for many years. MonoPan panels are used in welded honeycomb panels for commercial vehicle applications, reducing weight by 500 kg and increasing payload by 30%.

MonoPan Composites manufactures polypropylene honeycomb sandwich panels with glass fiber reinforced PP sheaths, which are used to make lightweight boxes for trucks made by leading automakers. Image source: Plasmatreat

About 10 years ago, with the construction of new paint factories and production facilities, the company needed an efficient, environmentally friendly and low-cost pretreatment solution to ensure the long-term adhesion of the paint to the non-polar resin used in the panel The conceptual requirements stipulate uniform wettability of large plastic surfaces, optimal adhesion of fillers and paints, continuous pretreatment of different panel geometries, and high productivity. Although there are several pretreatment methods that are not applicable, Plasmatreat (Steinhagen, Germany) stepped forward and built a new plasma device, the Openair-Plasma system, specifically tailored to meet the requirements of MonoPan Composites. 

According to MonoPan Composites, a year of preliminary testing immediately proved the effectiveness of Plasmatreat's Openair-Plasma technology for optimal paint adhesion. The level of surface tension determines the wettability of the skin. The higher the surface tension, the better the wetting ability. According to reports, test inks used to evaluate the surface activation of PP using Openair-Plasma showed that the surface tension-about 18 millinewtons/meter (mN/m) to 20 mN/m before plasma treatment-after plasma treatment Rise to 34 and 36 mN/m. Plasma treatment. This increase in surface tension, as well as the wettability of the skin, enables the skin to be printed, which is impossible when the surface tension is lower than 20 mN/m.

Other factors leading to its adoption are simplified online integration and high level of process reliability. The system also allows quick and flexible adjustment of the pretreatment process to adapt to different panel thicknesses. Plasmatreat said that in most cases, the technology can completely replace wet chemical and mechanical pretreatment processes.

Based on the jetting principle, Openair-Plasma operates at atmospheric pressure. With the help of an arc ignited in the jet and a working gas—usually air—the plasma is generated and then flows onto the product to be processed. The rotating nozzle performs this task, activating and electrostatically discharging the surface of the material at the same time, and performing fine cleaning at the same time. According to the jet geometry, the plasma that appears is said to be effective in a working range up to 25 mm wide and a treatment distance of 40 mm. The emitted plasma beam is also electrically neutral, which greatly expands the scope of application. 

Openair-Plasma technology uses natural atmospheric discharge as a model to generate plasma through high voltage for pretreatment of the material surface. Image source: Plasmatreat

In 2009, a tailor-made 2.80-meter-wide atmospheric pressure plasma system was officially integrated into the manufacturing process of MonoPan Composites to pre-process the 2.75-meter-wide and 17-30 mm-thick PP panels. PP panels are processed at a feed rate of 8 meters per minute, although Plasmatreat said that the feed rate can be increased as needed, and the device can ensure that the specified accuracy of the panel height difference is 1 mm. 28 RD1010 Openair rotating nozzles, staggered, 100 mm pretreatment width in each row, successfully cleaned and activated the entire panel width. It is said that the entire process only takes 20-40 seconds, depending on the size of the panel.

“The system automatically recognizes the width of the panel to be pre-processed and activates only the required number of plasma nozzles,” said Winfried Meyer, who was the Plasmatreat project manager at the time. In addition, as a complement to its easy-to-maintain design, Plasmatreat said that the plasma nozzle of the device can be raised to the required height and accessed via two sidewalks.

Today, MonoPan Composites pre-treats more than 120,000 square meters of panel material each year. For panel manufacturers, this process is still an important means to ensure consistent product quality.

"Plasmatreat's plasma jet technology has proven to be the perfect solution for fast and reliable pretreatment of our large format glass fiber reinforced polypropylene panels before coating," said Fabian Reich, Managing Director of MonoPan Composites. Reich said that with nearly 10 years of experience in atmospheric plasma use, the process will enable the company to continue to provide dry boxes weighing less than 3.5 tons and having the best quality for the growing market segment.

Welcome to the online SourceBook, which is the counterpart of the printed SourceBook Composites Industry Buyer's Guide published by CompositesWorld every year.

Compared with traditional materials such as steel, aluminum, iron and titanium, composite materials are still in a mature stage, and design and manufacturing engineers have only just begun to understand better. However, the physical properties of composite materials—combined with unparalleled weight reduction—make them undeniably attractive. 

Explains the old art behind the industry's first fiber reinforcement, and has an in-depth understanding of new fiber science and future development.

© 2021 Gardner Business Media, Inc. Privacy Policy [Login]