Bumper/fascia system, automotive

There is no single method for treating polymethane (PUR) waste, due to the different quantities, qualities, mixes, and cleanliness. It is estimated that some 125,000 t of RIM polyurethane is used worldwide, 85% in automotive parts, mainly in bumper fascias. Current technologies for physical recycling of PURs are mainly directed towards flexible and rigid foams, but systems have also been developed for recycling reinforced reaction injection molded (RRIM) PURs, on the... 

In fact, RIM was the first plastic to be approved for bumper fascia in North America to meet the low-temperature crashworthiness demanded by some OEMs. Unfortunately, due to process complexity, RIM could not be fabricated at a high enough rate to meet the demands of large car platforms. Faster cycle time for part production is delimited by the speed of curing chemistry and the ability of the resin to flow into molds. Furthermore, the automotive industry wanted to move away from the use of thermoset polymer systems that cannot be remelted. This attribute of thermosets was labeled by the industry as non-recyclable, and the industry made room for other thermoplastics such as TPO that can be remelted. Reaction-injection-molded parts are made from urethane epoxies, polyesters, and polyamides. A study of cost versus performance reported that RIM gives the best cost-performance characteristic for composite materials and is competitive with steel. ... 

Some degree of flexibility must be built into these primers because after topcoating with conventional basecoat and clearcoat, the flexible clearcoat systems have to pass the low-temperature impact resistance required for automotive bumper fascias and other components in the impact area of the vehicle. 

While plastics have been established as the material of choice for automotive fascia design efforts to provide more simplified, integrated bumper systems continue. Integration of the traditional steel or aluminum frame and impact-absorbing foam or honeycomb components has been achieved utilizing lightweight injection molded poly(carbonate)/polyester alloy or blow-molded poly(olefin). 

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