Stabilized moisture-curable polymeric compositions

1. A silane-crosslinkable polymeric composition, comprising:

a polyolefin having hydrolyzable silane groups;

an acidic silanol condensation catalyst;

a phenolic antioxidant having no tertiary-alkyl-substituted aryl or phenolic groups;

an ester-functionalized thioether; and

4,4′-di(dimethylbenzyl)diphenylamine.

2. The composition of claim 1 , wherein said ester-functionalized thioether has the following structure:

wherein R 3 is an alkylene radical having from 1 to 10 carbon atoms, R 4 and R 5 are individually any aliphatic or aromatic radical, optionally containing one or more heteroatoms.

3. The composition of claim 2 , wherein said ester-functionalized thioether has a structure selected from the following structures (I)-(II):

wherein R 6 is an alkyl radical having from 4 to 20 carbon atoms.

4. The composition of claim 3 , wherein said ester-functionalized thioether is selected from the group consisting of distearyl thiodipropionate, dilauryl thiodipropionate, pentaerythritol tetrakis(β-laurylthiopropionate), thiobis-[2-tert-butyl-5-methyl-4,1-phenylene] bis [3-(dodecylthio)propionate], and combinations of two or more thereof.

5. The composition of claim 1 , wherein said phenolic antioxidant has the following structure:

wherein R 1 is a linear or branched alkyl chain without heteroatoms and R 2 is an aliphatic or aromatic radical, optionally containing one or more heteroatoms.

6. The composition of claim 5 , wherein said phenolic antioxidant is selected from the group consisting of 2,2′-isobutylidene bis(4,6-dimethyl-phenol); 2,4-dimethyl-6-(1-methylpentadecyl)phenol; 2,2′-methylenebis(6-nonyl-p-cresol); 2,2′-(2-methylpropylidene)bis[4-methyl-6-(1-methylethyl)]phenol; 2,2′-Methylenebis(6-cyclohexyl-p-cresol); and mixtures of two or more thereof.

7. The composition of claim 1 , wherein said polyolefin having hydrolyzable silane groups is selected from the group consisting of (i) an interpolymer of ethylene and a hydrolyzable silane, (ii) an interpolymer of ethylene, one or more C 3 or higher α-olefins and/or unsaturated esters, and a hydrolyzable silane, (iii) a homopolymer of ethylene having a hydrolyzable silane grafted to its backbone, and (iv) an interpolymer of ethylene and one or more C 3 or higher α-olefins and/or unsaturated esters, such interpolymer having a hydrolyzable silane grafted to its backbone.

8. The composition of claim 1 , wherein said acidic silanol condensation catalyst is selected from the group consisting of alkyl aromatic sulfonic acids, hydrolyzable precursors of alkyl aromatic sulfonic acids, organic phosphonic acids, hydrolyzable precursors of organic phosphonic acids, halogen acids, and mixtures of two or more thereof.

9. The composition of claim 1 , wherein said polyolefin having hydrolyzable silane groups is present in an amount in the range of from 40 to 99.9 weight percent, based on the entire weight of said silane-crosslinkable polymeric composition; wherein said acidic silanol condensation catalyst is present in an amount in the range of from 0.01 to 0.50 weight percent, based on the entire weight of said silane-crosslinkable polymeric composition; wherein said phenolic antioxidant is present in an amount in the range of from 0.01 to 0.50 weight percent, based on the entire weight of said silane-crosslinkable polymeric composition; wherein said ester-functionalized thioether is present in an amount in the range of from 0.01 to 0.50 weight percent, based on the entire weight of said silane-crosslinkable polymeric composition.

10. A coated conductor, comprising:

(a) conductor; and

(b) a crosslinked polymeric composition prepared from the silane-crosslinkable polymeric composition of claim 1 ,

wherein said crosslinked polymeric composition surrounds at least a portion of said conductor.

11. A process for preparing a silane-crosslinkable polymeric composition, said process comprising: combining a polyolefin having hydrolyzable silane groups; an acidic silanol condensation catalyst; a phenolic antioxidant having no tertiary-alkyl-substituted aryl or phenolic groups; an ester-functionalized thioether; and 4,4′-di(dimethylbenzyl)diphenylamine to thereby form said silane-crosslinkable polymeric composition,

wherein said acidic silanol condensation catalyst, said phenolic antioxidant, and said ester-functionalized thioether are present in the form of a masterbatch when combined with said polyolefin having hydrolyzable silane groups,

wherein said masterbatch further includes at least one matrix resin.

12. The process of claim 11 , wherein said matrix resin is selected from the group consisting of low-density polyethylene, ethylene copolymers having one or more C3 or higher α-olefins or unsaturated esters, and combinations of two or more thereof.

13. The process of claim 11 , wherein said ester-functionalized thioether is selected from the group consisting of distearyl thiodipropionate, dilauryl thiodipropionate, pentaerythritol tetrakis(β-laurylthiopropionate), thiobis-[2-tert-butyl-5-methyl-4,1-phenylene] bis [3-(dodecylthio)propionate], and combinations of two or more thereof.

14. The process of claim 11 , wherein said phenolic antioxidant is selected from the group consisting of 2,2′-isobutylidene bis(4,6-dimethyl-phenol); 2,4-dimethyl-6-(1-methylpentadecyl)phenol; 2,2′-methylenebis(6-nonyl-p-cresol); 2,2′-(2-methylpropylidene) bis[4-methyl-6-(1-methylethyl)]phenol; 2,2′-Methylenebis(6-cyclohexyl-p-cresol); and mixtures of two or more thereof.

15. The process of claim 11 , wherein said polyolefin having hydrolyzable silane groups is selected from the group consisting of (i) an interpolymer of ethylene and a hydrolyzable silane, (ii) an interpolymer of ethylene, one or more C 3 or higher α-olefins and/or unsaturated esters, and a hydrolyzable silane, (iii) a homopolymer of ethylene having a hydrolyzable silane grafted to its backbone, and (iv) an interpolymer of ethylene and one or more C 3 or higher α-olefins and/or unsaturated esters, such interpolymer having a hydrolyzable silane grafted to its backbone.