Polyurethane waste recycling. 2. Polyol recovery and purification

In order to produce high-quality low-density polyurethane foam, a very pure polyether triol (polyol) is necessary. In this paper the liquid-liquid extraction of the polyol produced during base-catalyzed hydroglycolysis of waste polyurethane foams is described. The method utilizes the large changes in the solubility of polyol in hydrocarbons (such as hexadecanes) that occurs with changing temperatures. The sharp separation possible minimizes the contamination of the recovered polyols with unwanted reaction byproducts and also allows recovery of the glycol used in the hydroglycolysis reaction. A process to recycle waste polyurethane foam is described which incorporates this purification technique. The process produces a material capable of replacing as much as 50% o the virgin polyol used in high-quality, flexible low-density foam formulations. The economics of the process are attractive when no other market exists for the waste foam.