Polyolefin composition with increased resistance to cio2-containing water

A method for increasing the resistance of a polyolefin composition against degradation caused by contact with ClO2-containing water, by adding to said polyolefin composition an amount of antioxidant selected from

• a) phenols according to formula I:
• wherein
• R is a non-substituted or substituted aliphatic or aromatic hydrocarbyl radical which may comprise heteroatoms or R is a heteroatom,
• R′ and R″ independently are a non-substituted or substituted hydrocarbyl radical which may comprise heteroatoms or H,
• X1, X2 and X3 independently are a non-substituted or substituted hydrocarbyl radical which may comprise heteroatoms or H or OH, with at least X1, X2 or X3 being OH,
• n is 1 to 4, and
• at least one of the substituents R, R′ and/or R″ of the phenol comprises at least one sulphur, phosphorus and/or nitrogen heteroatom(s),
• or selected from
• b) amine compounds according to formula II:
• wherein R1, R2, R3, R4 and R5 independently are hydrogen or an aliphatic or aromatic hydrocarbyl radical, optionally comprising heteroatoms, and R6 is hydrogen,
• or selected from
• c) sulphur-containing compounds according to formula III:
• Ra—S—Rb,
• wherein Ra and Rb independently are an aliphatic or aromatic hydrocarbyl radical, optionally comprising heteroatoms.