ABSTRACT
In Japan, The Law for Recycling of Specified Kinds of Consumer Electric Goods has been enforced on April 1, 2001. And Japanese Appliance Manufacturers are obliged by this law to undergo the recycling of wasted refrigerators as well as air conditioners, televisions and washing machines.
Rigid polyurethane foam, about 10wt% of a refrigerator, is used as the thermal insulators. The Japanese Appliance market alone has an annual production of about 25,000 tons. But the recycling processes of rigid polyurethane foams have not been yet established.
We have studied chemical degradation methods of rigid polyurethane foams to raw materials (polyols) for the future target of the recycling law (recycling ratio of refrigerator; 90%). In this study we examined glycolysis reactivity of rigid polyurethane foam under various reaction conditions. The degradation rate was approximately doubled for each 10°C rise in the range of 170 to 200°C. This result shows the glycolysis reaction of rigid polyurethane foam obeys Arrhenius’s law. The degradation rate was proportional to the catalyst concentration in the case of KOH as catalyst. But dibutyltindilaurate concentration had less influence on the degradation rate. Faster degradation of polyurethane foam was achieved with smaller particle size and initial degradation rate was proportional to the surface area of foam particles. Polypropylene glycols had higher glycolysis reactivity than polyethylene glycols. Glycolysis reactivity also depended on the molecular weight of glycol and dipropylene glycol displayed the highest reactivity.
This work was supported, in part, by the New Energy and Industrial Technology Development Organization.
