General layout of a production unit

Free injection of a reactant mixture to an open mold followed by polymerization and solidification (curing, crystallization, and so on) in thermostated sets is the most widely used method of manufacturing large-sized moldings, such as plates, slabs, and other items of a simple or complicated shape. 

High volume production requires continuous lines for preparing the components for mixing. These lines feed into continuous mixers and then through filling devices into the mold, all in a rational layout designed to allow continuous processing. 

Flow sheets for preparing the components of various monomer and oligomer reactant mixtures do not differ significantly from each other, although they may have different sets of reactors. The choice depends mainly on the physical and chemical properties of the initial components. Fig. 4.2 shows a flow sheet for obtaining continuously molded polyurethane elastomers. Fig. 4.3 illustrates an elementary flow sheet for a batch process unit for manufacturing moldings of epoxy resin or epoxy-based composites filled with quartz sand. 

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