Powder Technology in Plastics Processing

Not all plastics processing plants have the same facility layouts and designs. Some
may engage automation systems while others may rely more on the labor forces.
But as far as material flow systems are concerned, there is little difference among
them. Figure 3.1 shows a typical material flow diagram of a plastics processing
plant.
As can be seen from Figure 3.1, after a solid bulk material such as resin is brought
to the plant by trucks, it will be stored in storage tanks until it is needed for processing.
Transportation of the bulk material from the storage tanks to the hoppers
of the processing machines when needed is usually carried out in pipes by pneumatic
conveying systems. If the bulk material is the only required raw material for
making the products, it will be the only material fed into the hopper. But when
additional raw materials (e.g., other types of resins and additives) are needed for
processing, all the ingredients will then be either separately discharged into the
hopper where they will be mixed and/or dehumidified, or they will be premixed
before being discharged into the hopper. In some circumstances, such as in making
masterbatches, dosing devices will be employed for monitoring the feeding into
the hopper that sits on a processing machine.
Finished products coming out from the processing machines need to be cooled and
solidified before they are stored in warehouses to wait for shipping. If the products
are semi-finished products like compounded resins or masterbatch concentrates,
drying and dewatering (if water baths are used for cooling) of the solidified strands
are required before they are pelletized, packed, and stored.
Echoing what was mentioned in Chapter 1 on the conceptual structural breakdown
of the plastics processing technology suggested by Tadmor and Gogos [1], the
above discussion on the basic flow of materials in the industry indicates that handling
particulate solids is the first processing component of

Dr. Anthony (Chi Ying) Wong is Market Coordinator - Asia Pacific at Badger Color Concentrates. He has over 35 years of experience in both industry and academia in the area of plastics and manufacturing, including postions at BASF, Exxon Chemical, and the University of Hong Kong. He holds a Ph.D. from the University of Bradford, UK.