Alpha-olefin-aromatic vinyl copolymer

1. A process for producing an atactic α-olefin-aromatic vinyl compound copolymer, the process comprising

copolymerizing in a temperature range of 50-200° C. an α-olefin with an aromatic vinyl compound in the presence of a polymerization catalyst comprising a transition metal compound (A) and a promoter catalyst component (B), wherein

the atactic α-olefin-aromatic vinyl compound copolymer comprises:

(I) the α-olefin, and

(II) 0.1 to 90 mole % of the aromatic vinyl compound,

wherein the atactic α-olefin-aromatic vinyl compound copolymer has a molecular weight distribution measured by a GPC method of 3.0 or less,

wherein in a 13 C-NMR measurement the following signals are present:

a signal (Sββ) based on an (aromatic vinyl compound-olefin-olefin) chain,

a signal (Sββ) based on an (aromatic vinyl compound-olefin-aromatic vinyl compound) chain,

a signal (Tββ) based on a blocking (aromatic vinyl compound-aromatic vinyl compound-aromatic vinyl compound) chain in the aromatic vinyl compound, and

a signal (Sββ) based on a blocking (olefin-olefin-olefin) chain in the olefin part;

wherein an index (θ) showing a blocking property of the aromatic vinyl compound component which is represented by the following relational equation is 10 to 80%:

θ= I ( Tββ+T βδ)/[ I ( Tδδ+TγδTββ+T βδ)]×100,

wherein I(Tββ+Tβδ) represents the sum of the intensities of the signals Tββ and Tβδ in the 13 C-NMR measurement, provided that

Tβδ represents a signal based on an (aromatic vinyl compound-aromatic vinyl compound-olefin) chain; and

I(Tδδ+Tγδ+Tβδ) represents the sum of the respective intensities of the signals Tδδ, Tγδ, Tββ and Tβδ based on all chains in which the aromatic vinyl compound participates among the chains of the above copolymer in the 13 C-NMR measurement,

Tδδ represents a signal based on an (olefin-aromatic vinyl compound-olefin) chain, and

Tγδ represents a signal based on a heterogeneous bond of an (aromatic vinyl compound-aromatic vinyl compound-olefin-olefin) chain or a signal based on a heterogeneous bond of an (aromatic vinyl compound-olefin-aromatic vinyl compound-olefin) chain,

wherein the component (A) in the polymerization catalyst is a transition metal compound Formula (1):

wherein

A 1 and A 2 each represent independently a cyclopentadienyl group, or a substituted cyclopentadienyl group;

Y 1 represents propylidene group;

Y 2 represents dimethylsilylene group;

M 1 represents titanium, zirconium or hafnium; and

X 1 and X 2 each represent independently a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group or an aryloxy group.

2. The process as described in claim 1 , wherein the index (θ) showing a blocking property of the aromatic vinyl compound component is 10 to 70%.

3. The process as described in claim 1 , wherein the aromatic ring is atactic in the chain of the aromatic vinyl compound component contained in the copolymer.

4. The process as described in claim 1 , wherein said polymerization catalyst further comprises an alkylating agent (C).

5. The process as described in claim 1 , wherein the promoter of the component (B) is selected from the group consisting of alumoxane, boroxane, borate, an ionic compound, a Lewis acid or clay and a mixture thereof.

6. The process as described in claim 4 , wherein the alkylating agent (C) is an organic aluminum compound, an organic magnesium compound or an organic zinc compound.

7. The process as described in claim 1 , wherein the aromatic vinyl compound is styrene.

8. The process as claimed in claim 1 , wherein the atactic α-olefin-aromatic vinyl compound copolymer has a molecular weight distribution of 1.5 to 3.0.

9. The process as claimed in claim 1 , wherein the atactic α-olefin-aromatic vinyl compound copolymer has a weight average molecular weight of 1,000 to 1,000,000.

10. The process as claimed in claim 1 , wherein the atactic α-olefin-aromatic vinyl compound copolymer has a weight average molecular weight of 5,000 to 800,000.

11. The process as claimed in claim 1 , wherein the atactic α-olefin-aromatic vinyl compound copolymer further comprises in copolymerized form a monomer selected from the group consisting of a cyclic olefin, a diene and mixtures thereof.

12. The process as claimed in claim 11 , wherein the atactic α-olefin-aromatic vinyl compound copolymer is a ternary copolymer.

13. The process as claimed in claim 11 , wherein the atactic α-olefin-aromatic vinyl compound copolymer is a quaternary copolymer.

14. The process as claimed in claim 1 , wherein the atactic α-olefin-aromatic vinyl compound copolymer is an ethylene-styrene copolymer, a propylene-styrene copolymer or a butane-1-styrene copolymer.

15. The process as claimed in claim 1 , wherein the amount of aromatic vinyl compound in the atactic α-olefin-aromatic vinyl compound copolymer is 0.1 to 30 mole %.

16. The process as claimed in claim 1 , wherein the amount of aromatic vinyl compound in the atactic α-olefin-aromatic vinyl compound copolymer is 35 to 90 mole %.

17. The process as claimed in claim 12 , wherein the ternary copolymer is selected from the group consisting of ethylene-styrene-norbornene copolymers, ethylene-styrene-butadiene copolymers, and ethylene-styrene-1.5-hexadiene copolymers.