COLOUR STABILISED POLYOLEFINS

A polyolefin composition which comprises: (a) a polyolefin containing transition metal catalyst residue (excluding metallic co-catalyst residues) at a level below 5 ppm based on the weight of the polyolefin; (b) optionally a first stabilising component consisting of a phenolic antioxidant or mixture of phenolic antioxidants; (c) optionally a second stabilising component consisting of a phosphite antioxidant or a mixture of phosphite antioxidants; and (d) a third stabilising component which acts also as a colour suppressant and which is a polyfunctional alcohol, amine or amide or mixtures thereof, with at least one of (b) and (c) present and with the proviso that if the phosphite antioxidant is trilauryl phosphite it must be used in combination with another phosphite. The preferred stabilising components (b) is 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6 dimethy-benzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione or mixed tocopherols. The preferred stabilising component (c) is Tris(mono-nonylphenyl)phosphite, Tris(2,4-di-t-butylphenyl)phosphite or bis(2,4-di-t-butyl phenyl)pentaerythritol diphosphite. The preferred stabilising component (d) which also acts as a colour suppressant component (d) is dipentaerythritol or tri-isopropanol amine. The preferred polyolefins are polypropylene and polyethylene. The polyolefin composition also may contain a hindered amine stabiliser (HAS) and an acid scavenger (e.g. calcium stearate).