Discolour-free silanol condensation catalyst containing polyolefin composition

1. Polyolefin composition comprising a crosslinkable polyolefin with hydrolysable silane groups and a silanol condensation catalyst, characterized in that said silanol condensation catalyst is an organic sulphonic acid comprising 10 C-atoms or more and that said polyolefin composition further comprises

(A) from 0.04 to 0.4 wt % of a compound selected from the group consisting of bis(2,4-dicumylphenyl)pentaerythritoldiphosphite and di-stearyl-pentaerythrityl-di-phosphite; and

(B) from 0.08 to 1.5 wt % of a non-phosphorous containing antioxidant selected from the group consisting of 1,3,5-tri-methyl-2,4,6-tris-(3,5-di-tert.butyl-4-hydroxyphenyl)benzene, 2,5,7,8-tetramethyl-2(4′,8′,12′-trimethyltridecyl)-chroman-6-ol, a butylated reaction product of p-cresol and dicyclopentadiene, and tetrakis-(methylene-(3,5-di-tert.butyl-4-hydrocinnamate))-methane.

2. Polyolefin composition according to claim 1 wherein the organic sulphonic acid contains the structural element

Ar(SO 3 H) x

with Ar being an aryl group which may be substituted or non-substituted, and x being at least 1.

3. Polyolefin composition according to claim 1 wherein the silanol condensation catalyst is present in an amount of 0.0001 to 6 wt %.

4. Polyolefin composition according to claim 1 wherein the crosslinkable polyolefin with hydrolysable silane groups is a polyethylene with hydrolysable silane groups.

5. Polyolefin composition according to claim 1 wherein in the crosslinkable polyolefin with hydrolysable silane groups the silane groups are present in an amount of 0.001 to 15 wt %.

6. Polyolefin composition according to claim 1 wherein the composition has an oxygen induction time of more than 30 min.

7. Article comprising the polyolefin composition according to claim 1 .

8. Pipe comprising the polyolefin composition according to claim 1 .

9. A polyolefin composition according to claim 1 , wherein the total amount of compound (A) and antioxidant (B) in the composition is from 0.2 to 1 wt. %.

10. A polyolefin composition according to claim 1 , wherein antioxidant (B) is selected from the group consisting of 1,3,5-tri-methyl-2,4,6-tris-(3,5-di-tert.butyl-4-hydroxyphenyl)benzene and tetrakis-(methylene-(3,5-di-tert.butyl-4-hydrocinnamate))-methane.

11. A polyolefin composition according to claim 1 , wherein compound (A) is present in an amount of 0.4 wt. %; and wherein antioxidant (B) is present in an amount of 0.15 wt. %.

12. Polyolefin composition comprising a crosslinkable polyolefin with hydrolysable silane groups and a silanol condensation catalyst, characterized in that said silanol condensation catalyst is an organic sulphonic acid comprising 10 C-atoms or more and that said polyolefin composition further comprises

(A) a compound selected from the group consisting of bis(2,4-dicumylphenyl)pentaerythritoldiphosphite and di-stearyl-pentaerythrityl-di-phosphite; and

(B) a non-phosphorous containing antioxidant selected from the group consisting of 1,3,5-tri-methyl-2,4,6-tris-(3,5-di-tert.butyl-4-hydroxyphenyl)benzene, 2,5,7,8-tetramethyl-2(4′,8′,12′-trimethyltridecyl)-chroman-6-ol, a butylate reaction product of p-cresol and dicyclopentadiene, and tetrakis-(methylene-(3,5-di-tert.butyl-4-hydrocinnamate))-methane;

wherein the amount of compound (A) and (B) is from 0.02 to 3 wt %.

13. Masterbatch for a crosslinkable polyolefin composition comprising a polymer and a silanol condensation catalyst, characterized in that said silanol condensation catalyst is an organic sulphonic acid comprising 10 C-atoms or more and that said masterbatch further comprises

(A) from 0.5 to 3.5 wt % of a compound selected from the group consisting of bis(2,4-dicumylphenyl)pentaerythritoldiphosphite and di-stearyl-pentaerythrityl-di-phosphite; and

(B) from 4 to 15 wt % of a non-phosphorous containing antioxidant selected from the group consisting of 1,3,5-tri-methyl-2,4,6-tris-(3,5-di-tert.butyl-4-hydroxyphenyl)benzene, 2,5,7,8-tetramethyl-2(4′,8′,12′-trimethyltridecyl)-chroman-6-ol, a butylated reaction product of p-cresol and dicyclopentadiene, and tetrakis-(methylene-(3,5-di-tert.butyl-4-hydrocinnamate))-methane.

14. Stabilized polyolefin containing cross-linked silane groups wherein cross-linking has been performed by the use of a silanol condensation catalyst, characterized in that said silanol condensation catalyst is an organic sulphonic acid comprising 10 C-atoms or more and that said stabilized polyolefin comprises

(A) from 0.04 to 0.4 wt % of a compound selected from the group consisting of bis(2,4-dicumylphenyl)pentaerythritoldiphosphite and di-stearyl-pentaerythrityl-di-phosphite; and

(B) from 0.08 to 1.5 wt % of a non-phosphorous containing antioxidant selected from the group consisting of 1,3,5-tri-methyl-2,4,6-tris-(3,5-di-tert.butyl-4-hydroxyphenyl)benzene, 2,5,7,8-tetramethyl-2(4′,8′,12′-trimethyltridecyl)-chroman-6-ol, a butylated reaction product of p-cresol and dicyclopentadiene, and tetrakis-(methylene-(3,5-di-tert.butyl-4-hydrocinnamate))-methane.

15. A stabilized polyolefin containing cross-linked silane groups wherein cross-linking has been performed by the use of a silanol condensation catalyst, characterized in that said silanol condensation catalyst is an organic sulphonic acid comprising 10 C-atoms or more and that said stabilized polyolefin comprises

(A) a compound selected from the group consisting of bis(2,4-dicumylphenyl)pentaerythritoldiphosphite and di-stearyl-pentaerythrityl-di-phosphite; and

(B) a non-phosphorous containing antioxidant selected from the group consisting of 1,3,5-tri-methyl-2,4,6-tris-(3,5-di-tert.butyl-4-hydroxyphenyl)benzene, 2,5,7,8-tetramethyl-2(4′,8′,12′-trimethyltridecyl)-chroman-6-ol, a butylated reaction product of p-cresol and dicyclopentadiene, and tetrakis-(methylene-(3,5-di-tert.butyl-4-hydrocinnamate))-methane

wherein the total amount of compound (A) and antioxidant (B) from 0.1 to 2 wt. %.