The Specialist Association of Foamed Plastics and Polyurethanes (FSK) award was presented in the category Technology – Processing and Chemistry, and the judges commended the increased cost-efficiency of the method and the partnering approach to the project.
Pultruded composites have proven successful in thermally insulating window frames and in reinforcing rotor blades for wind turbines. Covestro believes the process offers tremendous potential for the continuous manufacturing of composite parts, but its more widespread use has been hindered by an inadequate degree of industrialisation. In close cooperation, the three partners worked to enhance the chemistry, technology and process to significantly increase productivity as well as process and product quality. Processors can now cut costs significantly, Covestro reports.
The new iPul machines from KraussMaffei are said to be the first turnkey systems to incorporate system, process and die technology all from a single supplier. Critical processing parameters, such as output rate and haul-off rate, are controlled centrally. In the new systems the fibres are no longer impregnated in an open process, but rather by a metering machine in a closed injection chamber. Apart from eliminating odour problems for a pultruder’s employees, the technology supports precision temperature management during curing and thus increases production speeds. The systems are sensor-assisted and highly automated. Thanks to the injection chamber and metering device with newly engineered mixing head, a wide variety of resins can now be processed, including highly reactive polyurethane systems. The matrix material is injected at low pressure to further cut costs.
Polyurethane resins offer significant advantages over established pultrusion materials such as epoxy, unsaturated polyester and vinyl ester resins, Covestro claims. Their low viscosity, good fibre wetting and high reactivity support faster processing speeds than epoxies, which reduces manufacturing costs. The reaction time and viscosity of polyurethane resins can be varied widely, permitting the reproduction of even very thin component geometries.
Covestro markets the polyurethane systems Baydur PUL and Desmocomp for pultrusion. The former are liquid, two-component systems for fabricating highly durable profiles that display excellent thermal insulation properties and are used in window frames. Desmocomp displays good mechanical properties as well as UV and weathering resistance, making it suitable for outdoor applications. The IKV, with its experience in the fields of polyurethane processing and pultrusion with reactive resin systems, is supporting Covestro in its development efforts.