PROCESS FOR ADDITION OF ADDITIVES TO POLYMER PARTICLES

摘要

A polyolefin polymer powder for use in rotational moulding requires the presence of stabilizers, including UV-stabilizers, to prevent degradation during processing and use. Described is a new process for preparing rotomoulding polymer particles comprising (i) obtaining a plurality of polyolefin polymer particles having a mean particle size of 1 to 2000 mu m; (ii) heating a mixture of: A) at least one phenolic antioxidant; B) at least one organic phosphite or phosphonite antioxidant; C) at least one UV-stabiliser selected from Chimassorb 2020, Cyasorb UV 3346, Chimassorb 944, Cyasorb 4042 or Cyasorb 4611; D) a diluent; and optionally E) a metal stearate; to a temperature of between 20 and 200 DEG C; (iii) depositing the mixture onto said polyolefin polymer particles; and optionally (iv) blending a metal stearate to the resulting polyolefin polymer particles if component E was not present in said mixture.