POLYETHYLENE RESIN COMPOSITION FOR PIPE, METHOD OF PREPARING SAME, AND MOLDED ARTICLE PREPARED THEREFROM

To provide a polyethylene resin composition for pipe, which is all superior in resistance to sagging of pipe, resistance to slow crack growth, and an odor level.SOLUTION: There are provided a polyethylene resin composition for pipe which has a melt index (under a load of 5 kg, at 190°C) of 0.16 g/10 min to 0.24 g/10 min, and is prepared by passing through a two stage reactor, passing through an extruder, and adding a peroxide, wherein a rate of change in the melt index (MI) by the extruder is 60% to 90% according to Equation 1 below, and a rate of change in the melt index (MI) by the peroxide is 10% to 40% according to Equation 2 below, a method of preparing the same, and a molded article including the same. {(MI after passing through the two stage reactor-MI after passing through the extruder)/(MI after passing through the two stage reactor-final MI)}×100...(1) {(MI after passing through the extruder-MI after adding peroxide)/(MI after passing through the two stage reactor-final MI)}×100...(2)SELECTED DRAWING: None 【課題】パイプの垂れに対する抵抗性、低速亀裂成長に対する抵抗性及び臭気レベルのすべてに優れたパイプ用ポリエチレン樹脂組成物を提供する。【解決手段】溶融流れ指数（５ｋｇ荷重、１９０℃）（ＭＩ）が０．１６ｇ／１０分～０．２４ｇ／１０分であり、２段反応器通過、押出機通過及び過酸化物の添加により製造されるポリエチレン樹脂組成物において、前記押出機によるＭＩの変化率が下記式（１）によって６０％～９０％であり、前記過酸化物によるＭＩの変化率が下記式（２）によって１０％～４０％であるパイプ用ポリエチレン樹脂組成物、その製造方法及びそれを含む成形品に関する。｛（２段反応器通過後のＭＩ－押出機通過後のＭＩ）／（２段反応器通過後のＭＩ－最終ＭＩ）｝×１００...（１）｛（押出機通過後のＭＩ－過酸化物の添加後のＭＩ）／（２段反応器通過後のＭＩ－最終ＭＩ）｝×１００...（２）【選択図】なし