| 摘要 |
<p>1,254,209. Reuse of polyester resin. GOODYEAR TIRE & RUBBER CO. 25 Feb., 1969 [22 March, 1968], No. 9915/69. Heading C3R. A high molecular weight linear polyester resin is partially depolymerized by mixing with it one or more of water, glycols, dicarboxylic acids and phenyl, methyl, ethyl or propyl esters of dicarboxylic acids in an extrusion apparatus, heating and mixing vigorously the mixture formed under superatmospheric pressure to induce a degradation reaction, and extruding the degraded polyester. Preferably the polyester is mixed with 0-015 to 0-047 mol of reclaiming agent per mol of acid units in the polyester resin, and the pressure used is from 20 to 300 p.s.i. gauge. The resulting low molecular weight polyester preferably has an average degree of polymerization of 20 to 30. When the polyester resin is polyethylene terephthalate, the reclaiming agent may be water, ethylene glycol, terephthalic acid or dimethyl terephthalate, in which case the low molecular weight polyester produced will be a homopolyester. A copolyester may be produced by using as reclaiming agent acids or glycols other than those from which the polyester resin is derived. The low molecular weight resin produced by the process of the invention may be added to newly formed polyester resin prepolymer and condensed to form high molecular weight polyester resin.</p> |
