Transition metal catalytic systems and methods for preparing ethylene homopolymers or copolymers of ethylene and α-olefins using the same

1. A transition metal compound represented by Chemical Formula (1):

in the formula, M represents transition metal from Group 4 in the Periodic Table of Elements;

Cp represents cyclopentadienyl ring which is η 5 -linkable to M, or a fused ring containing a cyclopentadienyl ring, in which the cyclopentadienyl ring or the fused ring containing a cyclopentadienyl ring may be further substituted by (C1-C20)alkyl, (C6-C30)aryl, (C2-C20)alkenyl or (C6-C30)ar(C1-C20)alkyl;

Ar represents (C6-C14)arylene;

R 11 and R 12 independently represent hydrogen atom, (C1-C10)alkyl or (C6-C13)aryl(C1-C10)alkyl;

n is an integer from 0 to 3; R represents (C1-C10)alkyl, (C3-C10)cycloalkyl, (C6-C13)aryl, (C1-C10)alkyl(C6-C13)aryl, (C6-C13)ar(C1-C10)alkyl or (C1-C10)alkoxy; when n is 2 or 3, individual substituents of R may be same or different;

X 1 and X 2 independently represent halogen atom, (C1-C20)alkyl, (C3-C20)cycloalkyl, (C6-C30)aryl, (C6-C30)ar(C1-C20)alkyl, (C1-C20)alkoxy, (C6-C30)aryloxy, (C3-C20)alkylsiloxy, (C6-C30)arylsiloxy, (C1-C20)alkylamino, (C6-C30)arylamino, (C1-C20)alkylthio, (C6-C30)arylthio, (C1-C20)alkylphosphine, (C6-C30)arylphosphine, (C1-C20)alkylmercapto or (C6-C30)arylmercapto;

the alkyl, cycloalkyl, aryl, arylalkyl, alkoxy, aryloxy, alkylsiloxy, arylsiloxy, alkylamino, acylamino, alkylthio, arylthio, alkylphosphine, arylphosphine, alkylmercapto, arylmercapto of R n , X 1 and X 2 ; and the arylene of Ar may be independently substituted by one or more substituent(s) selected from a group consisting of halogen, (C1-C20)alkyl, (C3-C20)cycloalkyl, (C6-C30)aryl, (C6-C30)ar(C1-C20)alkyl, (C1-C20)alkoxy, (C6-C30)aryloxy, (C3-C20)alkylsiloxy, (C6-C30)arylsiloxy, (C1-C20)alkylamino, (C6-C30)arylamino, (C1-C20)alkylthio, (C6-C30)arylthio, (C1-C20)alkylphosphine, (C6-C30)arylphosphine, (C1-C20)alkylmercapto and (C6-C30)arylmercapto; or each of them may be linked to an adjacent substituent via (C3-C12)alkylene or (C3-C12)alkenylene with or without a fused ring to form an alicyclic ring, or a monocyclic or polycyclic aromatic ring.

2. The transition metal compound according to claim 1 , wherein Ar is selected from a group consisting of phenylene, naphthylene and fluorenylene.

3. The transition metal compound according to claim 2 , which is selected from those represented by one of Chemical Formulas (1-1) to (1-6):

wherein, Cp represents cyclopentadienyl or pentamethylcyclopentadienyl;

M represents titanium, zirconium or hafnium;

R 21 through R 24 independently represent hydrogen or (C1-C10)alkyl;

R 31 through R 36 independently represent hydrogen atom, (C1-C10)alkyl, (C3-C10)cycloalkyl, (C6-C13)aryl, (C1-C10)alkyl(C6-C13)aryl, (C6-C13)ar(C1-C10)alkyl or (C1-C10)alkoxy;

X 1 and X 2 independently represent chloride, methyl, methoxy, isopropoxy, benzyl, fluorenyl, fluorenyloxy or dimethylamino.

4. The transition metal compound according to claim 3 , which is selected from the following compounds:

wherein, Cp represents cyclopentadienyl or pentamethylcyclopentadienyl; and

X 1 and X 2 are independently selected from a group consisting of chloride, methyl, methoxy, isopropoxy, benzyl, fluorenyl, fluorenyloxy and dimethylamino.

5. A transition metal catalyst composition for preparing ethylene homopolymers or copolymers of ethylene with α-olefin, which comprises a transition metal compound, and alkylaluminoxane or organoaluminum cocatalyst, or boron compound cocatalyst, or a mixture thereof,

wherein the transition metal compound is represented by Chemical Formula (1):

in the formula, M represents transition metal from Group 4 in the Periodic Table of Elements;

Cp represents cyclopentadienyl ring which is η 5 -linkable to M, or a fused ring containing a cyclopentadienyl ring, in which the cyclopentadienyl ring or the fused ring containing a cyclopentadienyl ring may be further substituted by (C1-C20)alkyl, (C6-C30)aryl, (C2-C20)alkenyl or (C6-C30)ar(C1-C20)alkyl;

Ar represents (C6-C14)arylene;

R 11 and R 12 independently represent hydrogen atom, (C1-C10)alkyl or (C6-C13)aryl(C1-C10)alkyl;

n is an integer from 0 to 3; R represents (C1-C10)alkyl, (C3-C10)cycloalkyl, (C6-C13)aryl, (C1-C10)alkyl(C6-C13)aryl, (C6-C13)ar(C1-C10)alkyl or (C1-C10)alkoxy; when n is 2 or 3, individual substituents of R may be same or different;

X 1 and X 2 independently represent halogen atom, (C1-C20)alkyl, (C3-C20)cycloalkyl, (C6-C30)aryl, (C6-C30)ar(C1-C20)alkyl, (C1-C20)alkoxy, (C6-C30)aryloxy, (C3-C20)alkylsiloxy, (C6-C30)arylsiloxy, (C1-C20)alkylamino, (C6-C30)arylamino, (C1-C20)alkylthio, (C6-C30)arylthio, (C1-C20)alkylphosphine, (C6-C30)arylphosphine, (C1-C20)alkylmercapto or (C6-C30)arylmercapto;

the alkyl, cycloalkyl, aryl, arylalkyl, alkoxy, aryloxy, alkylsiloxy, arylsiloxy, alkylamino, arylamino, alkylthio, arylthio, alkylphosphine, arylphosphine, alkylmercapto, arylmercapto of R n , X 1 and X 2 ; and the arylene of Ar may be independently substituted by one or more substituent(s) selected from a group consisting of halogen, (C1-C20)alkyl, (C3-C20)cycloalkyl, (C6-C30)aryl, (C6-C30)ar(C1-C20)alkyl, (C1-C20)alkoxy, (C6-C30)aryloxy, (C3-C20)alkylsiloxy, (C6-C30)arylsiloxy, (C1-C20)alkylamino, (C6-C30)arylamino, (C1-C20)alkylthio, (C6-C30)arylthio, (C1-C20)alkylphosphine, (C6-C30)arylphosphine, (C1-C20)alkylmercapto and (C6-C30)arylmercapto; or each of them may be linked to an adjacent substituent via (C3-C12)alkylene or (C3-C12)alkenylene with or without a fused ring to form an alicyclic ring, or a monocyclic or polycyclic aromatic ring.

6. The transition metal catalyst composition for preparing ethylene homopolymers or copolymers of ethylene with α-olefin according to claim 5 , wherein Ar is selected from a group consisting of phenylene, naphthylene and fluorenylene.

7. The transition metal catalyst composition for preparing ethylene homopolymers or copolymers of ethylene with α-olefin according to claim 5 , wherein the transition metal compound is selected from those represented by one of Chemical Formulas (1-1) to (1-6):

wherein, Cp represents cyclopentadienyl or pentamethylcyclopentadienyl;

M represents titanium, zirconium or hafnium;

R 21 through R 24 independently represent hydrogen or (C1-C10)alkyl;

R 31 through R 36 independently represent hydrogen atom, (C1-C10)alkyl, (C3-C10)cycloalkyl, (C6-C13)aryl, (C1-C10)alkyl(C6-C13)aryl, (C6-C13)ar(C1-C10)alkyl or (C1-C10)alkoxy;

X 1 and X 2 independently represent chloride, methyl, methoxy, isopropoxy, benzyl, fluorenyl, fluorenyloxy or dimethylamino.

8. The transition metal catalyst composition for preparing ethylene homopolymers or copolymers of ethylene with α-olefin according to claim 5 , wherein the transition metal compound is selected from the following compounds:

wherein, Cp represents cyclopentadienyl or pentamethylcyclopentadienyl; and

X 1 and X 2 are independently selected from a group consisting of chloride, methyl, methoxy, isopropoxy, benzyl, fluorenyl, fluorenyloxy and dimethylamino.

9. The transition metal catalyst composition for preparing ethylene homopolymers or copolymers of ethylene with α-olefin according to claim 5 , wherein the ratio of transition metal to the alkylaluminoxane or organoaluminum cocatalyst to be used is from 1:50˜5,000 on the basis of the molar ratio of transition metal (M) to aluminum.

10. The transition metal catalyst composition for preparing ethylene homopolymers or copolymers of ethylene with α-olefin according to claim 9 , wherein the alkylaluminoxane or organoaluminum cocatalyst is selected from methylaluminoxane, modified methylaluminoxane, tetraisobutylaluminoxane, trialkylaluminum, triethylaluminum or triisobutylaluminum, or mixtures thereof.

11. The transition metal catalyst composition for preparing ethylene homopolymers or copolymers of ethylene with α-olefin according to claim 5 , wherein the ratio of transition metal, alkylaluminoxane or organoaluminum cocatalyst and boron compound cocatalyst is in the range of 1:0.5˜5:10˜500 on the basis of the molar ratio of transition metal (M):boron atom:aluminum atom.

12. The transition metal catalyst composition for preparing ethylene homopolymers or copolymers of ethylene with α-olefin according to claim 11 , wherein the boron compound cocatalyst is selected from N,N-dimethylanilinium tetrakispentafluorophenylborate or triphenylmethylinium tetrakispentafluorophenylborate, or mixtures thereof.

13. A process for preparing ethylene homopolymers or copolymers of ethylene with α-olefin by using the transition metal catalyst composition according to claim 5 , wherein the α-olefin is one or more compound(s) selected from propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene and 1-eitosene, and ethylene content of the copolymer of ethylene with olefin is from 50 to 99% by weight.

14. The process for preparing ethylene homopolymers or copolymers of ethylene with α-olefin according to claim 13 , wherein the pressure of ethylene monomer in the reactor is from 6 to 150 atm, and the polymerization temperature is from 60 to 250° C.