Abstract: A polyethylene resin composition comprising: (A) 50-99.9 parts by weight of an ethylene polymer; and (B) 0.1-50 parts by weight of a modified ethylene-.alpha.-olefin copolymer obtained by fluorinating an ethylene-.alpha.-olefin copolymer having the following properties (i) to (iv), said ethylene-.alpha.-olefin copolymer being prepared by copolymerizing ethylene with an .alpha.-olefin having 3 to 12 carbon atoms in the presence of a catalyst comprising a solid catalyst component and an organoaluminum compound, said catalyst component containing at least magnesium and titanium:______________________________________ (i) Melt index 0.01-100 g/10 min (ii) Density 0.860-0.910 g/cm.sup.3 (iii) Maximum peak tempera- not lower than 100.degree. C. ture (Tm) as measured according to differential scanning calorimetry (DSC) (iv) Boiling n-hexane insolu- not lower than 10 wt.

Abstract: A polyethylene resin composition comprising (A) 50-99.9 parts by weight of an ethylene polymer and (B) 0.1-50 parts by weight of a modified ethylene polymer obtained by fluorinating an ethylene polymer having a density in the range of larger than 0.910 g/cm.sup.3 and 0.970 g/cm.sup.3 ; said ethylene polymer being prepared by polymerizing ethylene in the presence of a catalyst comprising a catalyst component containing at least one member selected from the group consisting of a titanium compound, vanadium compound and chromium compound, and optionally an organoaluminum compound.