Processing, thermosets high production volumes

TPEs require moderately high production volume for good processing economics. Thermoplastics tooling costs are generally higher than those for thermoset rubber parts, some of which are compression molded in volumes of only a few hundred per year. 

Most of the high-volume automotive polymers arc thermoplastics the common virtues of polypropylene, ABS (acrylonitrile butadiene styrene), PVC (polyvinyl chloride), nylon, polyethylene and polycarbonate etc., are their versatility, ability to be injection moulded or extruded into intricate shapes, and suitability for mass production. Thermosets used in significant volume include phenolics, long used as electrical components, and now finding application in non-burning creep-resistant underbonnet items, and glass-reinforced polyesters, used originally in hand lay-up processes, but nowadays widely used in SMC. 

The process is generally used for high-volume production, because the cost of a modern semiautomatic press of modest capacity, say 50-75-ton clamping force, may be as much as 50,000, and a moderately sophisticated self-contained multicavity mold may also cost 50,000. Typical applications include melamine dinnerware, toaster legs and pot handles, and electrical ontlets, wall plates, and switches— parts that require the rigidity, dimensional stability, heat resistance, and electrical insulating properties typical of thermosetting compounds. 

Major requirements for book binding adhesives beyond adequate adhesion to the various substrates in the book include flexibility and die abihty to perform at cold and hot temperatures. The process of binding books is highly automated except in the case of special limited volume editions. New adhesives must therefor be adaptable to use on existing equipment, or new equipment must be developed for their use. New products such as thermoset polyurethane hot melts provide excellent adhesion and flexibility but new application technology is required for their use in high volume apphcadons with minimum equipment down time. 

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