Recycling thermoset plastics waste esp. polyurethane and polyurea

摘要

Recycling thermoset plastics waste or old articles (I), esp. polyurethane or polyurea, involves (a) reducing (I) to small pieces, e.g, turnings or granulate, with a size of max. 15mm, pref. max 5mm; (b) thermomechanical processing, esp. kneading, for 5-30 min at 130-180 deg.C; (c) mixing with a polyfunctional isocyanate (II) at max 80 deg.C in a mixer esp. a cold kneader, at max. 30 deg.C; (d) cooling the reaction mixt. immediately; and (e) then re-crosslinking by heating the mixt. in a mould for 5-20 min at 130-170 deg.C and at least 100 bar. Pref. (I) is reduced to a size of min. 0.5mm and freed from any interfering particles (e.g, lacquer, dust, reinforcing fibres) by wind classification and/or screening. Stage (b) is carried out for 15-24 min at 140-160 (150) deg. C pref. under pressure (esp. in a pressurised kneader) at 2-10 esp. 6 bar. In (c) the mixer temp. is 10-30, esp. 20 deg.C and temp. of the material max 60 deg.C. The mixt. is cooled within 10 min in (d) and the mixt. is processed within 24h after stages (c,d). In (e), crosslinking is carried out for 15 min at 135 deg.C.