Modified polyethylene resins and process for making the same

A process to make a modified polyethylene formulation, which process comprises the steps of:

• a) providing a starting polyethylene resin composition (SPEC) containing one or more polyethylene (co) polymer(s), wherein the SPEC has a melt index (12) of from 0.5 dg/min to 5 dg/min and contains
• i) from 0 to no more than 1.5 weight percent (based on the total weight of SPEC) of a high molecular weight Cumulative Detector Fraction-Light Scattering (CDFLS) fraction with a molecular weight (MW) of greater than 5,000,000 grams per mole (g/mol) and
• ii) from 0 to no more than 0.3 weight percent (based on the total weight of SPEC) of an ultra-high molecular weight CDFLS fraction with a molecular weight (MW) of greater than 10,000,000 g/mol;
• b) extruding and mixing together in a melt
• i) the SPEC,
• ii) a total quantity of one or more primary antioxidants that is effective to provide a concentration of least 2001 parts of the one or more primary antioxidants per 1 million parts by weight of the modified polyethylene formulation (“ppmw”), and
• iii) from 11 to 250 parts of free-radical generator per 1 million parts of the SPEC, by weight (“ppmw”), and
• iv) optionally, a total quantity of one or more secondary antioxidants that is effective to provide a concentration of at least 395 ppmw of the one or more secondary antioxidants in the modified polyolefin formulation,
• wherein the one or more primary antioxidants and the optional one or more secondary antioxidants are collectively referred to as the “primary and any secondary antioxidant(s)”;
• wherein the melt is maintained at a temperature and for a time sufficient to substantially decompose the free-radical generator without substantially degrading the polyethylene resin or the one or more primary antioxidants, such that a modified polyethylene formulation is produced which has:
• (i) a modified polyethylene resin component (MPEC) having
• 1. At least 2 weight percent (based on the total weight of MPEC) of a high molecular weight CDFLS fraction with a molecular weight (MW) of greater than 5,000,000 g/mol and
• 2. At least 0.3 weight percent (based on the total weight of MPEC) of an ultra-high molecular weight CDFLS fraction with a molecular weight (MW) of greater than 10,000,000 g/mol;
• and
• (ii) a total of at least 2,001 parts of the one or more primary antioxidant per 1 million parts of the MPEC by weight (ppmw);
• and
• (iii) less than 10 weight percent of polyethylene gels (based on the total weight of MPEC), and
• (iv) optionally, a total of at least 395 ppmw of the one or more secondary antioxidants.