Waste polyurethane

The recycling of contaminated polyurethane waste is described with reference to a glycolysis process developed by Bayer and Daimler-Benz in which the wastes from three-layer composite instrument panels are treated. The reuse of contaminated PU is achieved by dispersely integrating the impurities in the secondary polyol during the glycolytic dissociation. The impurities are modified in such a way that they act as a filler in the secondary polyol. 3 refs. 

J. Braslaw and J.L. Gerlock, Polyurethane Waste Recycling. Polyol Recovery and Purification, Ind. Eng. Chem. Process. Des. Dev. 23, 552 (1984). (series of articles). 

Today, several industrial plants based on glycolytic treatment are in operation for the chemical recycling of polyurethane wastes, mainly those generated from the insulation and automotive sectors.2... 

FIGURE 6.5 Reprocessing of polyurethane waste by thermopressing. (After Muller, P. and Reiss, R., Die Makromol. Chem., Macromol. Symp., 57, 175, 1992. With permission.)... 

As well as direct incineration of plastics waste, imder clean and efficient conditions, there has been some research into conversion into fuel oil, by chemical methods. The Veba Combi-Cracking (VCC) process produces synthetic crude oil under liquid phase hydration. In trials, 100 tonnes of mixed and contaminated plastics waste from normal domestic sources was hydrated to high quality oil, similar to that used as a source for diesel fuel. With metal-free granular material, costs were estimated at about DM 500/tonne. The process has also been used with polyurethane waste, producing oil that can be mixed with new oil (but costing over twice). 

Selected chemolysis processes for PET are illustrated in Figure 9.8 and tabulated in Table 9.6. These reactions yield either the original monomers or products that can be converted to other monomers. Hydrolysis can be effectively used with PET and polyurethane waste plastics in feedstock recovery (Zia et al., 2007). Reaction conditions employed are varied and these selected references do not cover them exhaustively. Aromatic polyesters, PET and poly(butylene terephthalate), have been studied intensively for feedstock recovery. PET is extensively used in soda bottles and less than 30% of the product is mechanically recycled. 

Eventually, the application of microwave irradiation for blowing of polyurethane foams led to reduction in the amount of amine catalysts required by half. The possibilities of the application of partially decomposed cellular polyurethane waste under microwave irradiation to formulate modem ecological systems for manufacturing heat-insulating foams were also presented. 

Simioni F, Bisello S and Tavan M (1983) Polyol recovery from rigid polyurethane waste, Cellular Polymers 2 281-293. 

Simioni F, Modesti M and Rienzi S A (1991) Recycling of polyurethane waste, Cellular Polymer P Int Conf, London. 

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