Edward Raymond, Holger Mueller
Papers # 2010 Vancouver
PVC-u, Calcium Carbonate, Direct Addition, Dry Blend Mixing Usually, PVC and additives are processed in a hot / cold mixer to yield a dry blend which is conveyed pneumatically to silos for intermediate storage. During the transfer process, the PVC and calcium carbonate can separate at high loading levels. This can lead to unstable extrusion behaviour, varying mechanical properties, and visible pipe defects. Direct Addition technology adds the calcium carbonate to the rigid PVC dry blend with a unique mixer immediately before the extruder feed throat. The addition of the carbonate with this technology eliminates the costly problems that can manifest from compound segregation.