Published On: Sat, May 14th, 2016

RIM casting lacquer system for plastic and wooden parts – efficient coating in injection mold

Superior surfaces with high freedom in design

Exceptional scratch resistance, from colorless to colored up to new metallic accents and self-healing effects are some of the properties with which decorative plastic and wooden parts can be finished directly in the reaction injection molding process. Continued development of the Puriflow casting lacquer system has made this possible. A coating that meets the highest optical and tactile demands, is done in the mold quickly and efficiently without external release agent, so that no sanding or polishing is needed.

plastics design

Superior surfaces with high freedom in design

Reaction injection molding (RIM) is a prototype process in which on one hand, molded parts are made from plastics through low-pressure injection and on the other hand, this technique is also used in back injection molding of trim parts, for e.g. of real wood veneer and foil. In both applications, the continued development of the tried and tested RIM casting lacquer process Puriflow of Votteler Lackfabrik offers potentialities to coat surfaces in the RIM process rapidly, economically and with design freedom previously unknown. Thereby the lacquer is applied in one shot process, so that when the part exits the machine it is already coated and finished.

Internal release agent increases productivity and lowers costs

The new generation of Puriflow coatings is equipped with an internal release agent for self-de-molding. Thus, there is no need to apply an external release agent on the mold after each shot any more. The production can run fully automatically without any interruption. This increases productivity on one hand, and on the other hand the component can be packed or processed without any post treatment. Last but not least, the costs for an external release agent are saved.

Modular system for individual design freedom

The solvent-free, two-component-Puriflow casting lacquers based on aliphatic Polyurethanes can be processed on casting machines bubble-free. With this lacquer various plastics such as PC, PC-ABS, ABS, PC-PBT, PC-ASA, ASA, TPU and even PP as well as carbon, composites as well as glass, foils and real wood veneers can be coated. This versatility opens up a very wide application range for interior and exterior parts in the automotive industry, in consumer goods, in electronics as well as everywhere where visible parts with high quality surface standards in large quantities are produced.

The modular structure also makes a substantial contribution to the casting lacquer system. It enables to customize the visual and tactile properties of the coating according to individual wishes and requirements. Whether transparent, piano black, high-quality reflective chrome finish or elegant iridescent, metallic accents, with innovative effects, deco – and brilliant varnishes in many shades, Puriflow opens up unprecedented freedom of design. The gloss levels range from high gloss to matt, the surfaces may be smooth or structured with soft-touch.

Coatings with leather grain or open-pore wood structures can also be depicted. In doing so, the variable hardness of coating – shore A 50 to D 83 – ensures that not only the visual impression, but also the tactile appears deceptively real. Compared to the originals, surfaces achieved in this manner are much easier to clean and more durable.

High resistance

The high resistance is owing to the high physical and chemical stability of the coating system. The coated surfaces are light, chemical, heat and climate change resistant, low in yellowing and UV-resistant. When it comes to scratch resistance, they not only meet the stringent requirements of the automotive and consumer goods industry, but exceed them, sometimes even up to 1.8 times. Even with the “car wash” test of AMTEC Kistler, parts coated with Puriflow regularly achieve good results. Therefore, this coating system has the approval of various automobile manufacturers.

Self-healing effect makes the scratches disappear on their own

plastics design

Superior surfaces with high freedom in design

Since, even with high resistance not every single scratch can be avoided, this coating is equipped with a certain self healing (reflow effect) potency. This will ensure that scratches, above a certain temperature – depending on the system – sometimes also at room temperature -regress and/or are no longer visible.

Easy, safe and clean to work with the new 3K-mixing head

The two components of the lacquer are injected in to the form during the casting process. When color is added to it as the third component, the new 3K-mixing heads make it possible for the lacquer to be directly injected on to the part. This makes changing color so easy and fast as in a spray application and prevents the contamination of the plant.

The casting over and cross linking takes between two and three minutes depending on the part geometry and Puriflow type. The attributes profile of materials with regard to viscosity, reactivity and color stays stable on the production plant for the duration of the application over several days.

Compared to multi- layer coating, RIM casting offers besides significant time savings also significant material savings. There is no over spray. The coating is used virtually 100 percent and it produces no emissions. In addition, the fully automated process ensures minimized rejects and thereby for overall reduced lacquer costs and at the same time higher sustainability.

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