Abstract: The present invention relates to an antioxidant composition comprising (a) 0.01-0.5% by weight of sterically hindered phenolic compound, (b) 0.01-0.5% by weight of phosphorous compound, and (c) 0.01-1% by weight of sulphurcontaining compound. Said antioxidant composition reduces degradation of plastic materials during processing and end-use and thus, increases the long term thermal stability of those plastic materials. Moreover, this invention relates to methods for producing a final polymeric article with an increased long term thermal stability and stabilization against ageing by radical decomposition processes and polymeric intermediate materials as well as polymeric articles comprising the inventive antioxidant composition.

Abstract: The invention provides a process for the preparation of a moulded polymer item, said process comprising obtaining a polymer moulding powder having a mean particle size of 1 to 2000 &mgr;m comprising an admixture of UV-stabilizer-loaded polymer particles and non-UV-stabilizer-loaded polyolefin polymer particles, loading said powder into a mould, heating and rotating said mould to melt said powder, cooling said mould, and releasing said moulded polymer item from said mould.

Abstract: 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 &mgr;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 ° 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.

Abstract: A polyolefin polymer powder for use in rotational molding requires the presence of stabilizers, including UV-stabilizers, to prevent degradation during processing and use. It has been found that the polymer may be stabilized by a particular blend of additives or by the addition of a masterbatch of UV-stabilizer loaded polymer particles. Also, it has been found that polymer particles made using a supported catalyst manufactured using a mechanically fluidized bed, a product particularly suitable for rotomolding may be produced.