Broad Application Range for MDI/pMDI
MDI and pMDI are utilized in a wide range of applications related to molded, formed and pressed materials. Chem-Trend has a long established history developing mold release agents that work with these materials. Our experience is broadest when related to the manufacturing of polyurethane molded products (most often MDI) or in the wood composite/panel pressing industry where the use of pMDI is on the rise.
MDI Usage in the Manufacture of Polyurethane Foams
Although there are many differences between MDI- and TDI-reacted polyurethanes, both can be used for Polyurethane High Resiliency foams. MDI reacts at a lower temperature than TDI and the foams can be processed at lower temperatures – typically from 40-65°C compared to 60-75°C for TDI foams.
Releasing the foams from their molds is not merely a question of stickiness – both MDI and TDI reacted are quite tacky in the free-rise state – it’s also a matter of the processing temperature, especially the mold temperature. As with most chemical reactions, the higher the temperature, the faster the reaction rate. As polyurethane goes from liquid to solid state, its viscosity rises and the ability of the foam to flow and disperse throughout the mold decreases. Therefore, the mold release agent needs to be tuned to the specific process being utilized. If, for example, the gelling reaction at the surface is increased by adding a catalyst, this could reduce the ability of the foam to flow and cause under filling. Additionally, at higher temperatures the release film becomes softer until eventually it is liquid enough to cause foam defects. These aspects need to be taken into account when developing a mold release agent for a given application.
At Chem-Trend, we understand the diversity between the various MDI applications and how they relate to our customers’ processes. The importance de-molding, release and mold cleaning has on the efficiency of those processes – as well as on product quality -- remains the focus of our work. To learn more about our expertise in the field of polyurethane molding and how we can help you read our main Polyurethane Molding page or contact us to speak with one of our polyurethane industry experts.
Trends in Wood Composites Increase use of pMDI
Increasingly tighter controls on formaldehyde emissions will continue to impact the wood composite/panel pressing industry. pMDI binder systems do provide some attractive benefits to the wood composite processor, such as faster processing times, good moisture resistance and zero formaldehyde emissions. Already, some in the industry have moved toward the use of pMDI, however, these systems can be rather difficult to process – the composite bound to it can be quite sticky and display a tendency toward build-up on the pressing surface. This may prove more difficult to release than “traditional” binders and, in fact, pMDI has been known to increase the rate of build-up on pressing surfaces.
Chem-Trend has formulated mold release agents to get to the heart of the issue of pMDI resin systems. Build-up simply cannot gain a foot-hold on the pressing surface when our release agents are utilized, ensuring that the manufacturing plant can remain in operation for extended periods of time. To learn more about the products that we continue to develop to address the utilization of pMDI in wood composites industries read our main Wood Fiber Composites/Panel pressing page or contact us to speak with one of our wood composite industry experts.