Ethylene copolymer composition

An ethylene copolymer composition comprising:

• (A-1) an ethylene/.alpha.-olefin copolymer of ethylene with an .alpha.-olefin of 3 to 20 carbon atoms having such properties that
• (i) the density (d) is in the range of 0.880 to 0.960 g/cm.sup.3,
• (ii) the melt flow rate (MFR) at 190.degree. C. under a load of 2.16 kg is in the range of 0.01 to 200 g/10 min,
• (iii) the temperature (Tm(.degree.C.)) at which the endothermic curve of said copolymer measured by a differential scanning calorimeter (DSC) shows the maximum peak and the density (d) satisfy the relation
• Tm<400.times.d-250,
• (iv) the melt tension (MT(g)) at 190.degree. C. and the melt flow rate (MFR) satisfy the relation
• MT>2.2.times.MFR.sup.-0.84,
• (v) the flow index (FI(1/sec)) defined by a shear rate which is given when a shear stress of molten copolymer at 190.degree. C. reaches 2.4.times.10.sup.6 dyne/cm.sup.2 and the melt flow rate (MFR) satisfy the relation
• FI>75.times.MFR, and
• (vi) the amount (W(% by weight)) of a decane-soluble portion at 23.degree. C. and the density (d) satisfy the relation,
• in the case of MFR.ltoreq.10 g/10 min,
• W<80.times.exp (-100(d-0.88))+0.1;
• in the case of MFR>10 g/10 min,
• W<80.times.(MFR-9).sup.0.26 .times.exp (-100(d-0.88))+0.1;
• and
• (B-1) a high-pressure radical polymerization low-density polyethylene having such properties that
• (i) the melt flow rate (MFR) is in the range of 0.1 to 50 g/10 min, and
• (ii) the molecular weight distribution (Mw/Mn, Mw=weight-average molecular weight, Mn=number-average molecular weight) measured by GPC and the melt flow rate (MFR) satisfy the relation
• Mw/Mn.gtoreq.7.5.times.log (MFR)-1.2;
• a weight ratio ((A-1):(B-1)) between said ethylene/.alpha.-olefin copolymer (A-1) and said high-pressure radical polymerization low-density polyethylene (B-1) being in the range of 98:2 to 70:30.