Abstract
We have studied the chemical recycling of wastes from unsaturated polyester resin products such as buttons for clothes.The resin wastes were ground and decomposed in glycol with an acid, base or ester exchange catalyst. The decomposition rate by the basic catalyst was larger than that by the acid or the ester exchange catalyst. When they were treated with ethylene glycol and NaOH catalyst for 2.0 hrs at 290°C, the decomposition of 84.6% was attained and the molecular weight of a resulting product showed Mn = 156 and Mw / Mn = 1.06. The decomposition at 200°C gave a phthalic glycol. The destruction of crosslinking in a styrene/fumarate copolymer was observed at the temperatures over 230°C. The same phenomenon could occur, too, in the case of a styrene / maleic anhydride (75/25) copolymer in glycol at such a high temperature. The degradation product was then reacted with maleic anhydride to give a new unsaturated polyester (Mn = 846, Mw = 7,468 : cf., the commercial one; Mn = 1,646, Mw = 5,366). The bending strength of the recycled resin was 77.8 MPa (the commercial one : 92.1 MPa).
