Ethylene polymer

An ethylene-based polymer which is a copolymer obtained from ethylene and a C3 to C10 α-olefin and satisfies the following requirements (i), (ii), (iii) and (iv) simultaneously:

• (i) melt flow rate [MFR2 (g/10 min)] under a loading of 2.16 kg at 190° C. is in the range of 0.01 to 10,
• (ii) melt tension [MT (g)] and the above melt flow rate [MFR2 (g/10 min)] satisfy the following relationship:
• MT≧3.2×MFR2−0.55
• (iii) an activation energy [Ea] of fluidization is less than 30 (KJ/mol), and
• (iv) swell ratio is 1.36 or more,
• wherein said ethylene-based polymer is obtained by copolymerizing ethylene with a C3 to C10 α-olefin, in the presence of a solid catalyst component carried on (C) a solid carrier:
• (A1) a group 4 transition metal compound represented by the general formula [I] below,
• (A2) a group 4 transition metal compound represented by the general formula [II] below, and
• (B) at least one compound selected from:
• (b-1) an organometallic compound,
• (b-2) an organoaluminum oxy compound, and
• (b-3) a compound reacting with the transition metal compound (A1) or (A2) to form an ion pair,
• where M represents a transition metal atom in the group 4 in the periodic table, m represents an integer of 1 to 4, R1 represents a branched or linear aliphatic hydrocarbon group or an optionally substituted alicyclic hydrocarbon group, R2 to R6 may be the same or different and each represent a hydrogen atom, a halogen atom, a hydrocarbon group, a heterocyclic compound residue, an oxygen-containing group, a nitrogen-containing group, a boron-containing group, a sulfur-containing group, a phosphorus-containing group, a silicon-containing group, a germanium-containing group or a tin-containing group, two or more of which may be bound to one another to form a ring, and when m is 2, two of the groups represented by R2 to R6 be bound to each other provided that R1's shall not be bound to each other, and n is a number satisfying the valence of M, X represents a hydrogen atom, a halogen atom, a hydrocarbon group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group, a boron-containing group, an aluminum-containing group, a phosphorus-containing group, a halogen-containing group, a heterocyclic compound residue, a silicon-containing group, a germanium-containing group or a tin-containing group, and when n is 2 or more, a plurality of groups represented by X's may be the same or different, and a plurality of groups represented by X's may be bound to one another to form a ring,
• where R7 R20 are selected from hydrogen, a hydrocarbon group and a silicon-containing group, and may be the same or different, adjacent substituents R7 R20 be bound to each other to form a ring, M is a group 4 transition metal atom, Y is a group 14 atom, Q may be selected in the same or different combination from a halogen, a hydrocarbon group, an anion ligand, and a neutral ligand capable of coordination with a lone pair of electrons, j is an integer of 1 to 4, at least one of R19 and R20 is an unsubstituted aryl group or a substituted aryl group, and when both R19 an R20 are either unsubstituted aryl groups or substituted aryl groups, R19 and R20 may be the same or different.