ALDEHYDE CONTENT REDUCTION PROCESS AND RECYCLED POLYOLEFIN WITH LOW ALDEHYDE CONTENT

A process for treating plastic waste chips containing a blend of polypropylene and polyethylene in an amount of at least 83.0 wt.-% to less than 100 wt.-% and further containing C7 to C11 aldehydes and limonene, the process comprising the steps of: (a) providing plastic waste chips in a treatment vessel having inlet and outlet for gas at opposite sides at upper and lower part section of the treatment vessel, whereby the plastic waste chips contain - C7 to C11 aldehydes in an amount of 8000 ppb to 20000 ppb as determined by using HS-SPME-GC x GC-MS; and further contain - limonene in an amount of 5 ppm to 500 ppm as determined by using HS-SPME-GC-MS (b) optionally washing and drying said plastic waste chips of step (a); (c) optionally preheating said plastic waste chips to a temperature in the range of 20°C to a point 10°C below the Vicat softening point (10N, ISO 306) of said plastic waste chips; (d) subjecting said plastic waste chips, in a fixed bed without stirring under standard pressure or reduced pressure, to a gas flow for achieving a Reynolds number in the range of 35 to 1200 at a temperature in the range of 20°C to a point 10°C below the Vicat softening point (10N, ISO 306) of said plastic waste chips; (e) recovering the treated plastic waste chips containing * C7 to C11 aldehydes in a total amount of 50 ppb to less than 5000 ppb as determined by using HS-SPME-GC x GC-MS and * limonene in an amount of 0.5 to 5 ppm as determined by using HS-SPME-GC-MS; (f) subjecting said treated plastic waste chips of step (e) to an extrusion step yielding pellets; (g) recovering said pellets. L'invention concerne un procédé de traitement de copeaux de déchets plastiques contenant un mélange de polypropylène et de polyéthylène à raison d'au moins 83,0 % en poids à moins de 100 % en poids et contenant en outre des aldéhydes en C7 à C11 et du limonène, le procédé comprenant les étapes consistant à : (a) introduire des copeaux de déchets plastiques dans une cuve de traitement comportant un orifice d'entrée et un orifice de sortie pour gaz au niveau des côtés opposés de la section de partie supérieure et inférieure de la cuve de traitement, les copeaux de déchets plastiques contenant des aldéhydes en C7 à C11 à raison de 8 000 ppb à 20 000 ppb comme déterminé par HS-SPME-GC x GC-MS ; et contenant en outre - du limonène à raison de 5 ppm à 500 ppm comme déterminé par HS-SPME-GC-MS, (b) éventuellement laver et sécher lesdits copeaux de déchets plastiques de l'étape (a) ;