Bumper recycling technology

Norio Sato, Hidero Takahashi and Toshio Kurauchi 

The necessity to develop an appropriate technology for the recycling of automotive plastic parts has become a key issue in recent years, in terms of environmental protection and preservation of resources. It is obvious that plastics recycling in the automotive industry will focus on bumpers, which are relatively large, and can be dismantled into their constituents easily. 

Toyota CRDL and Toyota Motor Company have developed a Tjumper to bumper recycling system for painted thermoplastics (elastomer modified polypropylene and Toyota Super Olefin Polymer (TSOP), hereeifter referred to as TP) bumpers. 

Paint separation Separation by specific gravity + filtration X O O 

The paint peeling methods specified in (b) are divided into a mechanical peeling method and chemical peeling method. For the mechanical peeling method, shot-blast and waterjet methods were evaluated. The shot-blast method is to spray particulate agents on a painted TP bumper surface by means of compressed air in order to peel off the paint film. The water-jet method uses high pressure water instead of particulate. Both of them are unsuitable for the treatment of such bulky products with complex geometries as bumpers. 

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Typical products are elastomer modified heterophasic copolymers (heco), as compounded or reactor TPOs. Talc, typically below 20%, is added for higher stiffness and lower coefficient of thermal expansion (LCTE). The latter is an important condition for zero-gap concepts, in which the bumper follows very closely the line of the body fascia. Now that bumpers painted in body colors have become a standard feature, paint adhesion and enhanced surface finish have become important criteria. These can be influenced by optimizing the polymer structure and rubber content. The recycling aspects are treated in the chapter on Bumper recycling technology in this book. 

The bumper to bumper recycling system based on the pressurized hydrolysis technology and bumper discrimination technology has been... 

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... 

The pressurized hydrolysis technology is available for all TP bumpers of Toyota cars, which are painted with acrylic-melamine resin or alkyd-melamine resin. However, the recovered bumpers contain some repaired ones which are repainted with urethane paint film. The pressurized hydrolysis technology is not available for the urethane paint film because this film is not hydrolyzable with water vapor in such conditions. To maintain the high performance of the recycled material, the repaired bumper must be sorted from the recovered TP bumpers. Considering the difference of the chemical reaction of the paint films with dye agents, a paint film dyeing method was develop>ed. A nonrepaired bumper which is painted with acrylic- or alkyd-melamine resin becomes red and fluorescent color when a mixture of dye agent of Acid Red 52 and a solvent of lactic acid are applied. On the other hand, a repaired bumper... 

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