Alkylaryl and arylalkyl monosulfonic acid catalysts for crosslinking polyethylene

A process for crosslinking a polyolefin modified with hydrolyzable alkoxysilane groups in the presence of moisture employing a silanol condensation catalyst selected from the group consisting of:

• (i) an alkylated naphthalene monosulfonic acid substituted with 1-4 alkyl groups wherein each alkyl group is a linear or branched alkyl with 5-20 carbons with each alkyl group being the same or different, wherein the total number of carbons in the alkyl groups is in the range of 20 to 80 carbons;
• (ii) an arylalkyl sulfonic acid wherein the sulfonic acid is attached to the alkyl group, the aryl is phenyl or naphthyl and is substituted with 1-4 alkyl groups wherein each alkyl group is a linear or branched alkyl with 5-carbons with each alkyl group being the same or different, and wherein the total number of carbons in the alkyl groups is in the range of 12-80;
• (iii) a derivative of (i) or (ii) selected from the group consisting of an anhydride, an ester, an acetylate, an epoxy blocked ester and an amine salt thereof which is hydrolyzable to the corresponding alkyl naphthalene monosulfonic acid or the arylalkyl sulfonic acid;
• (iv) a metal salt of (i) or (ii) wherein the metal ion is selected from the group consisting of copper, aluminum, tin and zinc;
• wherein the process steps comprise:
• forming a master batch of the silanol crosslinking catalyst with a polyolefin;
• mixing the master batch with an alkoxysilana functional polyolefin to form a mixture at a concentration of 0.0005 to 0.0005 mM/g of the silanol crosslinking catalyst in the mixture;
• heating and extruding the mixture as a coating onto a wire;
• and
• curing the extruded coating at a trmperature of 25° C. to 50° C. at a relative humidity of 25% to 100%.