KraussMaffei technology allows you to add expandable graphite to polyurethane foam | World of composites

KraussMaffei expandable graphite dosing technology allows the material to be used as a fire retardant, substitute or additive to liquid mixtures.
Requirements for fire resistance of polyurethane foam parts are increasing worldwide, both in the automotive and industrial sectors, as well as due to regulatory requirements. To meet this demand, KraussMaffei (Munich, Germany) announced that it will present a complete system for high pressure processing of expandable graphite to achieve high material and process efficiency, and the Cleaner Production exhibition will be held in Düsseldorf, Germany from October 16 to 2017 year. 19th.
“Expandable graphite is a cost-effective filler that offers clear advantages for many automation applications,” explains Nicholas Bale, President of the Reaction Equipment Division at KraussMaffei. “Unfortunately, this material is sensitive to mechanical stress during processing.”
KraussMaffei’s newly developed high-pressure mixing head with low-pressure bypass and a special pre-mixing station for dosing expanding graphite make it a particularly effective alternative or additive to liquid additives as a fire retardant. Fully automated process chains reduce component cycle times and increase overall system efficiency.
KraussMaffei claims that the benefits of high-pressure countercurrent injection mixing for precision machining of highly reactive polyurethane foam systems can be exploited in applications where expandable graphite is used as a filler. This reportedly forms the basis for reducing cycle times and increasing production efficiency. In this process, unlike low-pressure processing, the self-cleaning mixing head is said to eliminate the need for flushing after each injection. KraussMaffei says this saves materials and production time and helps maintain consistent product quality, while also eliminating the cost of providing and disposing of flushing materials. Higher pressure mixing also achieves higher mixing energies. This can be used to reduce cycle time.
This technology is based on special expandable graphite mixing heads. The new mixing head is based on the KraussMaffei high-pressure mixing head. The system is equipped with a low-pressure bypass of increased cross-section and is designed for processing expandable graphite. Consequently, the mechanical stress exerted on the expanding graphite particles between cycles of successive cycles of charged polyol is minimized. Just before pouring begins, the material circulates through the nozzle, creating pressure. Therefore, the filler is subject to minimal mechanical stress. With this technology, high filling levels are possible, depending on the requirements and the raw material system, up to more than 30% by weight of polymer. Therefore, it can reach the high level of fire resistance UL94-V0.
According to KraussMaffei, the mixture of polyol and expanding graphite is prepared in a special pre-mixing station. Special blenders evenly mix the filling with liquid ingredients. This is done in a gentle manner, thus maintaining the structure and size of the expandable graphite particles. Dosing is automated and the polyol weight can be increased by up to 80%, ensuring consistent quality. Additionally, production becomes cleaner and more efficient as manual handling, weighing and filling steps are eliminated.
During the premixing process, the mixing ratio of expanding graphite and other components can be used to optimize the weight and volume of the components without compromising fire retardant properties.

Post time: Oct-09-2023