Unsaturated polyesters transportation applications

Polyester resins. The fire-performance characteristics of unsaturated polyester resins are of utmost importance in many application areas, particularly in the construction, transportation and electronics industries ( 1 3). Consequently, these plastics represent one of the major growth areas for fire retardants in recent years ( 1 4). 

Transportation applications include exterior automotive body components, non-appearance automotive parts, structural components, plus numerous truck, bus and rail car applications. Unsaturated polyester resins compete on the basis of weight reduction, corrosion resistance and parts consolidation. Thermoplastic resins, however, offer steep competition. 

The growth of unsaturated polyesters will continue to be fueled by their versatility and their ability to provide cost-effective solutions to end-use requirements. Unsaturated polyester composites will continue to provide solutions to engineering demands for corrosion resistance, strength-to-weight and cost performance. Marine, transportation and construction opportunities currently identified and being developed will provide growth beyond the existing applications presented. Some examples are as follows ... 

In the transportation industry, there is an ever increasing use in auto, truck and bus applications. The advent of the electric vehicle, which may demand vastly improved weight reduction over today s state-of-the-art vehicles, would be a natural extension of current unsaturated polyester resin technologies. 

Resins based on dicyclopentadiene (DCPD) offer better wettability of fillers and better prevention of print-through than conventional unsaturated polyesters, making them particularly suitable for appearance parts in transportation and marine applications. Polyesters based on DCPD require special chemical competence on the part of the fabricator, but... 

Such glass fiber-reinforced composites based on the unsaturated polyester thermosets are usually fabricated as sheet molding compounds (SMC) and bulk molding compounds (BMC). These are widely used in various metal replacement applications because of their cost-effectiveness, rigidity, light weight, and corrosion resistance properties particularly useful in transportation (cars and trucks), constmction, pipe, and tank applications. Automotive and tmck body panel and strucmral component applications of SMC include doors, hatchbacks, hoods, front grilles, etc. Some nonautomotive applications of SMC and BMC include sanitaryware (bathtubs, shower stalls, sinks), appliances, business machine, and electrical components. 

Unsaturated polyesters (UPs) have been used extensively in the reinforced plastics industry in the manufacture of products for transportation, construction and marine applications. They are also used for coatings, finishes, lacquers, cements and glues... 

The use of fiber reinforced unsaturated polyester resin composites in the form of sheet molding compound (SMC), bulk molding compound (BMC) and preform molding exceeded 475 000 tons (approximately one billion pounds) in North America and Europe in 1995. Many applications were in the transportation industry such as automotive body panels, truck components and semi-structural parts (Table 1). Other applications are in sanitary ware (bathtubs, showers, sinks), applicances, business machines and electrical components. 

About 8,000 metric tons of peroxides were consumed in 1972. This consumption was strongly stimulated by the rapid growth in reinforced plastics (Ref 23). The largest volume product is benzoyl peroxide which is used in polystyrene and polyester markets for such items as toys, automobiles, furniture, marine, transportation and mil requirements. Also, methyl ethyl ketone peroxide is used in large volumes to cure (as a catalyst) styrene-unsatur-ated polyester adhesive resins used in mil ammo adhesive applications, as well as in glass fiber reinforced plastic products such as boats, shower stalls, tub components, automobile bodies, sports equipment, etc. The monoperesters are growing slowly because of some substitution of the peroxydicarbonates and azo compds (Refs 8,9 23)... 

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