POLYETHYLENE RESIN COMPOSITION FOR HIGH PRESSURE PIPE COMPRISING METALLOCENE-BASED POLYETHYLENE, COMPATIBILIZER AND LOW MOLECULAR WEIGHT POLYMER

摘要

PURPOSE: Provided is a polyethylene resin composition for high pressure pipe which has excellent environmental stress cracking resistance and strength against external pressure, thereby reducing the thickness of a pipe produced therefrom. CONSTITUTION: The polyethylene resin composition comprises (A) 100 parts by weight of metallocene-based polyethylene; (B) 0.1-10 parts by weight of organically modified montmorillonite; (C) 0.5-30 parts by weight of a compatibilizer, wherein ethylenically unsaturated carboxylic acid, ethylenically unsaturated carboxylic acid ester or ethylenically unsaturated carboxylic acid anhydride is grafted into a main chain of polyethylene; and (D) 0.01-5 parts by weight of Ziegler-Natta system polyethylene having a molecular weight of 3000 or less. Particularly, the metallocene-based polyethylene has a melt index of 0.1-5g/10min as measured at a load of 5 kg and at a temperature of 190 deg.C by ASTM D 1238 and a density of 940 g/cm3 or more. The composition may further comprise an acid resistant, an antioxidant and/or processing aids.