Transition metal compound as catalyst component for polymerization, aromatic vinyl compound-olefin copolymer having stereoregularity and method for its preparation by means of the transition metal compound as catalyst component

Abstract: A transition metal compound of the following formula (1) as catalyst component for the production of an aromatic vinyl compound polymer or an aromatic vinyl compound-olefin copolymer: wherein A is an unsubstituted or substituted benzindenyl group of the following formula K-2, K-3 or K-4: wherein each of R1 to R3 is hydrogen, a C 1-20 alkyl group, a C 6-10 aryl group, a C 7-20 alkylaryl group, a halogen atom, OSiR 3 , SiR 3 or PR 2 (wherein each R is a C 1-10 hydrocarbon group), provided that the plurality of R1, the plurality of R2 and the plurality of R3 may be the same or different, respectively, and each pair of adjacent R1, adjacent R2 and adjacent R3 may together, with the atoms joining them, form a 5- to 8- member aromatic or aliphatic ring, B is an unsubstituted or substituted benzindenyl group of the same chemical formula as A, or an unsubstituted or substituted cyclopentadienyl group, an unsubstituted or substituted indenyl group or an unsubstituted or substituted fluorenyl group, of the following formula K-5, K-6 or K-7: wherein each of R4 to R6 is hydrogen, a C 1-20 alkyl group, a C 6-10 aryl group, a C 7-20 alkylaryl group, a halogen atom, OSiR 3 , SiR 3 or PR 2 (wherein each R is a C 1-10 hydrocarbon group), provided that the plurality of R4, the plurality of R5 and the plurality of R6 may be the same or different, respectively, when both A and B are unsubstituted or substituted benzindenyl groups, they may be the same or different, Y is a methylene group or a silylene group, which has bonds to A and B and which has, as substituents, hydrogen or a C 1-15 hydrocarbon group, wherein the substituents may be the same or different from each other, or Y may have, together with the substituents, a cyclic structure, X is hydrogen, a halogen atom, an alkyl group, an aryl group, an alkylaryl group, a silyl group, a methoxy group, an ethoxy group, an alkoxy group or a dialkylamide group, and M is zirconium, hafnium or titanium.

Description: The present invention relates to a transition metal compound as catalyst component for polymerization, a method for producing an aromatic vinyl compound type polymer employing it, a method for producing an aromatic vinyl compound polymer and an aromatic vinyl compound-olefin copolymer, having an isotactic stereoregularity, and a novel aromatic vinyl compound-olefin copolymer. For the production of a copolymer of an olefin with an aromatic vinyl compound, such as ethylene with styrene, studies have been conducted primarily by using so-called heterogeneous Ziegler-Natta catalysts (e.g. Polymer Bulletin, 20 , 237-241 (1988), Macromolecules, 24 , 5476 (1991)). However, conventional heterogeneous Ziegler-Natta catalyst systems are not so practical, since the catalytic activities are low, the styrene content in the product is very low at a level of a 1 mol%, or the product does not have a uniform regular copolymer structure or contains a substantial amount of homopolymers such as polyethylene and isotactic or atactic polystyrene. Further, the stereoregularity of the obtained polystyrene is isotactic, but in the copolymerization, no stereoregularity of an alternating structure of styrene and an olefin is observed, or an alternating structure itself is not substantially contained. Further, some styrene-ethylene copolymers obtainable by using so-called single-site catalyst systems comprising a transition metal compound and an organoaluminum compound, and methods for their production, have been known. JP-A-3-163088 and JP-A-7-53618 disclose styrene-ethylene copolymers where no normal styrene chain is present i.e. so-called pseudo random copolymers, obtained by using a complex having a so-called constrained geometrical structure. Here, a normal styrene chain is meant for a head-to-tail bond chain. Further, hereinafter styrene may sometimes be represented by St. However, phenyl groups in the alternating structure of styrene-ethylene present in such pseudo random copolymers, have no stereoregularity. Further, no normal styrene chain is present, whereby the content of styrene can not exceed 50 mol%. Further, the catalytic activities are practically inadequate. JP-A-6-49132, EP-A-0 572 990, and Polymer Preprints, Japan, 42 , 2292 (1993) disclose methods for producing similar styrene-ethylene copolymers wherein no normal St chain is present, i.e. so-called pseudo random copolymers, by using a catalyst comprising a bridged metallocene type Zr complex and a cocatalyst. However, according to Polymer Preprints, Japan, 42 , 2292 (1993), phenyl groups in the alternating structure of styrene-ethylene present in such pseudo random copolymers, have no substantial stereoregularity. Further, like in the case of a complex having a constrained geometrical structure, no normal styrene chain is present, and the styrene content can not exceed 50 mol%. The catalytic activities are also practically inadequate. Further, it has recently been reported to produce a styrene-ethylene copolymer close to an alternating copolymer having a stereoregularity under a condition of an extremely low temperature (-25°C) by using 1,2-ethylene(-CH 2 -CH 2 -) bridged bisindenyl type Zr complex; rac[ethylenebis(indenyl)zirconium dichloride] (Macromol. Chem., Rapid Commun., 17 , 745 (1996)). However, from the 13C-NMR spectrum disclosed, it is evident that this copolymer has no normal styrene chain. Further, if copolymerization is carried out at a polymerization temperature of at least room temperature by using this complex, only a copolymer having a low styrene content and a low molecular weight is obtainable. On the other hand, a styrene-ethylene alternating copolymer obtainable by using a Ti complex having a substituted phenol type ligand, is known (JP-A-3-250007 and Stud. Surf. Sci. Catal., 517 (1990)). This copolymer has a feature that it consists essentially of an alternating structure of ethylene and styrene and contains substantially no other structure such as an ethylene chain, a structure comprising an ethylene chain and styrene or a structure of e.g. a head-to-head or tail-to-tail bond (hereinafter referred to as a heterogeneous bond) of styrene. The alternating index (value λ in the present specification) of the copolymer is at least 70, substantially at least 90. Namely, the resulting copolymer is a copolymer having a very high degree of alteration and consisting substantially solely of the alternating structure, whereby it is substantially difficult to change the compositional ratio of the copolymer consisting of 50 mol% of ethylene and 50 mol% of styrene. Further, the stereoregularity of phenyl groups is isotactic, but the isotactic diad index m is about 0.92, whereby the melting point is low at a level of from 110 to 120°C. Further, the weight average molecular weight is low at a level of 20,000, which is inadequate to provide practically useful physical properties as a crystalline polymer. It should also be added that the catalytic activities are very low, and the copolymer can hardly be regarded as practically useful, since it is obtained as a mixture with e.g. syndiotactic polystyrene. It has been attempted to produce a copolymer of a propylene with styrene by means of a Solvay type Ziegler-Natta catalyst (Macromolecules, 22 , 2875 (1989)). However, the catalytic activities are low, and the styrene content is at a level of 4.4 mol% at best. With respect to a single-site catalyst system comprising a transition metal compound and an organoaluminum compound, a case wherein a Ewen-type zirconium complex which is a so-called metallocene catalyst, is employed for copolymerization of propylene with styrene, is known (JP-A-8-269134). However, the styrene content of the copolymer thereby obtainable is as low as a few %, and the stereoregularity is syndiotactic. The production of an isotactic aromatic vinyl compound polymer such as an isotactic polystyrene, has been studied by means of a so-called heterogeneous Ziegler-Natta catalyst. For example, such a catalyst is disclosed in Macromolecules, 24 , 5476 (1991), but the catalytic activities are low, and as a fate of a heterogeneous Ziegler-Natta catalyst, due to non-uniform active sites, the molecular weight distribution (Mw/Mn) tends to be as broad as at least 3, and cation polymerization and other polymerizations tend to simultaneously proceed, and a substantially a large amount of atactic polystyrene is usually produced as a by-product. On the other hand, in the polymerization of styrene using a single-site catalyst, syndiotactic polystyrene is usually obtained. Only when a nickel-type non-metallocene complex is used, formation of isotactic polystyrene has been reported, for example, in Macromolecules, 29 , 4172 (1996). However, the molecular weight, the catalytic activities and the stereoregularities are all inadequate. In any case, no isotactic polystyrene has been obtained with a system using a metallocene complex as a catalyst component. It is an object of the present invention to provide a metal compound for polymerization, a method for producing an aromatic vinyl compound type stereoregular polymer by using it, a method for producing an aromatic vinyl compound polymer and an aromatic vinyl compound-olefin copolymer, having isotactic stereoregularity, and a novel aromatic vinyl compound-olefin copolymer. Firstly, the present invention provides a transition metal compound of the following formula (1) as catalyst component for the production of an aromatic vinyl compound polymer or an aromatic vinyl compound-olefin copolymer: wherein A is an unsubstituted or substituted benzindenyl group of the following formula K-2, K-3 or K-4: wherein each of R1 to R3 is hydrogen, a C 1-20 alkyl group, a C 6-10 aryl group, a C 7-20 alkylaryl group, a halogen atom, OSiR 3 , SiR 3 or PR 2 (wherein each R is a C 1-10 hydrocarbon group), provided that the plurality of R1, the plurality of R2 and the plurality of R3 may be the same or different, respectively, and each pair of adjacent R1, adjacent R2 and adjacent R3 may together, with the atoms joining them, form a 5- to 8- member aromatic or aliphatic ring, B is an unsubstituted or substituted benzindenyl group of the same chemical formula as A, or an unsubstituted or substituted cyclopentadienyl group, an unsubstituted or substituted indenyl group or an unsubstituted or substituted fluorenyl group, of the following formula K-5, K-6 or K-7: wherein each of R4 to R6 is hydrogen, a C 1-20 alkyl group, a C 6-10 aryl group, a C 7-20 alkylaryl group, a halogen atom, OSiR 3 , SiR 3 or PR 2 (wherein each R is a C 1-10 hydrocarbon group), provided that the plurality of R4, the plurality of R5 and the plurality of R6 may be the same or different, respectively, when both A and B are unsubstituted or substituted benzindenyl groups, they may be the same or different, Y is a methylene group or a silylene group, which has bonds to A and B and which has, as substituents, hydrogen or a C 1-15 hydrocarbon group, wherein the substituents may be the same or different from each other, or Y may have, together with the substituents, à cyclic structure, X is hydrogen, a halogen atom, an alkyl group, an aryl group, an alkylaryl group, a silyl group, a methoxy group, an ethoxy group, an alkoxy group or a dialkylamide group, and M is zirconium, hafnium or titanium. The unsubstituted benzindenyl group may, for example, be 4,5-benz-1-indenyl (another name: benz(e)indenyl), 5,6-benz-1-indenyl, or 6,7-benz-1-indenyl, and the substituted benzindenyl group may, for example, be 4,5-naphtho-1-indenyl, 4,5-pyrene-1-indenyl, 4,5-triphenylene-1-indenyl, α-acenaphtho-1-indenyl, 3-cyclopenta[c]phenanthryl or 1-cyclopenta[1]phenanthryl. Particularly preferably, the unsubstituted benzindenyl may, for example, 4,5-benz-1-indenyl (another name: benz(e)indenyl), 5,6-benz-1-indenyl, or 6,7-benz-1-indenyl, and the substituted benzindenyl group may, for example, be α-acenaphtho-1-indenyl, 3-cyclopenta[c]phenanthryl, or 1-cyclopenta[1]phenanthryl. In the above formula (1), B is preferably the same unsubstituted or substituted benzindenyl group as above A, or an unsubstituted or substituted cyclopentadienyl group, an unsubstituted or substituted indenyl group or an unsubstituted or substituted fluorenyl group, of the following formula K-5, K-6 or K-7: In the above K-5 to K-7, each of R4, R5 and R6 is hydrogen, a C 1-20 alkyl group, a C 6-10 aryl group, a C 7-20 alkylaryl group, a halogen atom, OSiR 3 , SiR 3 or PR 2 (wherein each R is a C 1-10 hydrocarbon group), the plurality of R4, the plurality of R5 and the plurality of R6 may be the same or different, respectively. However, B is preferably in a racemic-form (or pseudo racemic-form) with A. Particularly preferably, B is, as an unsubstituted benzindenyl group, 4,5-benz-1-indenyl, 5,6-benz-1-indenyl or 6,7-benz-1-indenyl, or as a substituted benzindenyl group, α-acenaphtho-1-indenyl, 3-cyclopenta[c]phenanthryl, or 1-cyclopenta[1]phenanthryl, or as an unsubstituted indenyl group, 1-indenyl, or as a substituted indenyl group, 4-phenylindenyl or 4-naphthylindenyl. The unsubstituted cyclopentadienyl may, for example, be cyclopentadienyl, and the substituted cyclopentadienyl may, for example, 4-aryl-1-cyclopentadienyl, 4,5-diaryl-1-cyclopentadienyl, 5-alkyl-4-aryl-1-cyclopentadienyl, 4-alkyl-5-aryl-1-cyclopentadienyl, 4,5-dialkyl-1-cyclopentadienyl, 5-trialkylsilyl-4-alkyl-1-cyclopentadienyl, or 4,5-dialkylsilyl-1-cyclopentadienyl. The unsubstituted indenyl group may, for example, be 1-indenyl, and the substituted indenyl group may, for example, be 4-alkyl-1-indenyl, 4-aryl-1-indenyl, 4,5-dialkyl-1-indenyl, 4,6-dialkyl-1-indenyl, 5,6-dialkyl-1-indenyl, 4,5-diaryl-1-indenyl, 5-aryl-1-indenyl, 4-aryl-5-alkyl-1-indenyl, 2,6-dialkyl-4-aryl-1-indenyl, 5,6-diaryl-1-indenyl, or 4,5,6-triaryl-1-indenyl. The unsubstituted fluorenyl group may, for example, be a 9-fluorenyl group, and the substituted fluorenyl group may, for example, be a 7-methyl-9-fluorenyl group or a benz-9-fluorenyl group. In-the above formula (1), Y is carbon or silicon which has bonds to A and B and which has substituents, and it is a methylene group or a silylene group having, as substituents, hydrogen or a C 1-15 hydrocarbon group. The substituents may be the same or different from each other. Further, Y may have a cyclic structure such as a cyclohexylidene group or a cyclopentylidene group. Preferably, Y is a substituted methylene group which has bonds to A and B and which is substituted by hydrogen or a C 1-15 hydrocarbon group. The hydrocarbon group may, for example, be an alkyl group, an aryl group, a cycloalkyl group or a cycloaryl group. The substituents may be the same or different from each other. Particularly preferably, Y is -CH 2 -, -CMe 2 -, -CEt 2 -, -CPh 2 -, cyclohexylidene or cyclopentylidene. Here, Me is a methyl group, Et is an ethyl group and Ph is a phenyl group. X is hydrogen, a halogen atom, a C 1-15 alkyl group, a C 6-10 aryl group, a C 8-12 alkylaryl group, a silyl group having a C 1-4 hydrocarbon substituent, a C 1-10 alkoxy group, or a dialkylamide group having a C 1-6 alkyl substituent. The halogen atom may, for example, be chlorine or bromine, the alkyl group may, for example, be a methyl group or an ethyl group, and the aryl group may, for example, be a phenyl group. The alkylaryl group may, for example, be a benzyl group, the silyl group may, for example, be trimethylsilyl, the alkoxy group may, for example, be a methoxy group, an ethoxy group or an isopropoxy group, and the dialkylamide group may, for example, be a dimethylamide group. X may be the same or different from each other, or having a bond structure between X. Especially when X is a dimethylamide group, the transition metal catalyst component of the present invention can be produced by the method disclosed in WO95/32979, whereby there is a merit that such a catalyst component can simply and inexpensively be produced. Namely, it can be produced by a single step from a ligand compound and zirconium tetrakisdimethylamide at a temperature of at least room temperature, where control is easy. Strictly, the transition metal catalyst component produced by this process is a racemic-form containing a substantial amount of meso-form as an impurity. However, inclusion of the meso-form in the catalyst gives no substantial influence in the present invention. In the case of a transition metal complex wherein X is chlorine, a highly costly process for reacting a dimethylamide type complex with a dimethylamine hydrochloride at a low temperature, such as -78°C is required, whereby the product will be expensive. Further, when X is a dimethylamide, the speed for forming active species after contacting with methylalumoxane-as the cocatalyst, tends to be slightly slow as compared with a case where X is chlorine. This has an important merit from the viewpoint of the production process in that particularly in a batch solution polymerization, in a polymerization method of preliminarily dissolving a cocatalyst in the polymerization solution and introducing a transition metal compound to the polymerization solution under prescribed condition to initiate the polymerization, active species are gradually formed during the polymerization, whereby abrupt generation of polymerization heat immediately after the introduction of the catalyst can be reduced, and heat removal of the polymerization liquid can be facilitated. M is zirconium, hafnium or titanium. Particularly preferred is zirconium. The following compounds may be mentioned as specific examples of such a transition metal compound as catalyst component. For example, dimethylmethylene bis(4,5-benz-1-indenyl)zirconium-dichloride (another name: dimethylmethylenebis(benz-e-indenyl)zirconium dichloride), di-n-propylmethlenebis(4,5-benz-1-indenyl)zirconium dichloride, di-i-propylmethylenebis(4,5-benz-1-indenyl)zirconium dichloride, cyclohexylidenebis(4,5-benz-1-indenyl)zirconium dichloride, cyclopentylidenebis(4,5-benz-1-indenyl)zirconium dichloride, diphenylmethylenebis(4,5-benz-1-indenyl)zirconiumm dichloride, dimethylmethylene(cyclopentadienyl) (4, 5-benz-1-indenyl)zirconium dichloride, dimethylmethylene(1-indenyl)(4,5-benz-1-indenyl)zirconium dichloride, dimethylmethylene(1-fluorenyl)(4,5-benz-1-indenyl)zirconium dichloride, dimethylmethylene(4-phenyl-1-indenyl) (4, 5-benz-1-indenyl)zirconium dichloride, dimethylmethylene(4-naphthyl-1-indenyl)(4,5-benz-1-indenyl)zirconium dichloride, dimethylmethylenebis(5,6-benz-1-indenyl)zirconium dichloride, dimethylmethylene(5,6-benz-1-indenyl) (1-indenyl)zirconium dichloride, dimethylmethylenebis(4,7-benz-1-indenyl)zirconium dichloride, dimethylmethylene(6,7-benz-1-indenyl)(1-indenyl)zirconium dichloride, dimethylmethylenebis(4,5-naphtho-1-indenyl)zirconium dichloride, dimethylmethylenebis(α-acetonaphtho-1-indenyl)zirconium dichloride, dimethylmethylenebis(3-cyclopenta(c)phenanthryl)zirconium dichloride, dimethylmethylene(3-cyclopenta(c)phenanthryl)(1-indenyl)zirconium dichloride, dimethylmethylenebis(1-cyclopenta(1)phenanthryl)zirconium dichloride, dimethylmethylene(1-cyclopenta(1)phenanthryl)(1-indenyl)zirconium dichloride, dimethylmethylenebis(4,5-benz-1-indenyl)zirconium bis(dimethylamide), and dimethylmethylene(1-indenyl) (4,5-benz-1-indenyl)zirconium bis(dimethylamide), may be mentioned. In the foregoing, zirconium complexes were exemplified, but corresponding titanium complexes and hafnium complexes may also suitably be used. Further, racemic-form or mixtures of racemic-form and meso-form may also be employed. Preferably, racemic-form or pseudo racemic-form are employed. In such a case, D-isomers or L-isomers may be employed. The following excellent characteristics are obtainable when an aromatic vinyl compound polymer or an aromatic vinyl compound-olefin copolymer is produced by using the transition metal compound of the present invention as a polymerization catalyst component. The catalytic activities are high, and the polymer or the copolymer can be obtained at a high productivity of a level of at least 1×10 8 (g/mol·transition metal catalyst) in the case where the aromatic vinyl compound content is less than 20 mol%, or at least 4.1×10 7 (g/mol·transition metal catalyst) when the aromatic vinyl compound content is at least 20 mol% and less than 55 mol%. Further, it is possible to produce a random copolymer having a high aromatic vinyl compound content, particularly an aromatic vinyl compound-ethylene random copolymer wherein the aromatic vinyl compound content exceeds 55 mol%. Especially when a polymerization catalyst comprising a transition metal compound as catalyst component having a 3-cyclopenta(c)phenanthryl group as ligand A or A and B, such as rac-dimethylmethylenebis(3-cyclopenta(c)phenanthryl)zirconium dichloride, and a cocatalyst, is employed, it is possible to produce a styrene-olefin random copolymer, particularly a styrene-ethylene random copolymer, and an isotactic polystyrene, having a high molecular weight, under very high catalytic activities. In such a case, particularly with respect to a copolymer wherein the aromatic vinyl compound content is at least 50 mol%, it is possible to produce a copolymer having a weight average molecular weight of at least 100,000, preferably 200,000. Further, the styrene-ethylene random copolymer thereby obtained, has a characteristic that it is a copolymer having a high random nature (low alternating nature) as compared with a case with the same aromatic vinyl compound content under the same polymerization condition. The isotacticity of the structure contained in the resulting polymer or copolymer is very high. Secondly, the present invention provides a transition metal compound of the following formula (2-1) or (2-2) as catalyst component for the production of an aromatic vinyl compound polymer or an aromatic vinyl compound-olefin copolymer: wherein A, B, Y, M and X are as defined with respect to the formula (1), wherein the angle (the bite angle) between metal M and the centroid of each cyclopentadienyl structure in A and B, is at most 12°. The bite angle can be obtained by X-ray diffraction of a single crystal of the transition metal catalyst component or by the following calculation method employing a computer. SGI Origin Work Station was employed which has IRIX6.4 mounted as an operation system and which has MIPS R10000 Processo Chip Revision 2.6 2×180 MHz IP27 processors as CPU. The employed softwares were Molecular orbital method G94revision, E. 2, Gaussian 94 (manufactured by Gaussian Inc.) and Option (Geom, OPT, HF, DIRECT, STO-3G). The results of the study carried out with respect to dimethylmethylene(cyclopentadienyl)(fluorenyl)zirconium dichloride are shown below, which substantiate that the method of obtaining a bite angle by such a calculation, is proper. Bite angle obtained by the above calculation method: 119° Bite angle obtained by single crystal X-ray diffraction method: 117.9° Literature value: Macromol. Chem., Macromol. Symp., 48/49 , 253 (1991). The two values substantially agree, thus substantiating that the calculation method is proper. Calculation results Formulas Y Bite angle Formula (2-1) Dimethylmethylene group 119° Dimethylsilylene group 126° Formula (2-2) Dimethylmethylene group 111° Dimethylsilylene group 121° By variously changing the structures of A and B, bite angles were obtained by calculation, and such bite angles agreed to one another within a difference of 1°. Namely, the structures of A and B do not affect the bite angle. The present inventors have studied the content of an aromatic vinyl compound in the aromatic vinyl compound-olefin copolymer under the same condition using various transition metal compound as catalyst components. As a result, it has been found that a very high aromatic vinyl compound content can be obtained when a transition metal catalyst component having a bite angle of at most 120° is employed. Such a bite angle can be accomplished when in the above formula (2-1) or (2-2), Y is a methylene group having hydrogen or a C 1-15 hydrocarbon group. In the case of the formula (2-2), two Y may be the same or different. Among a group of.the above-mentioned transition metal catalyst components, the formula (2-1) represents a group of transition metal catalyst components in which Y is a methylene group which has bonds to A and B and which has, as substituents, hydrogen or a C 1-15 hydrocarbon group. In the case of the formula (2-2), the following compounds may be mentioned as examples of such a transition metal catalyst component: (1,2'-methylene)(2,1'-methylene)bis(4,5-benz-1-indenyl)zirconium dichloride, (1,2'-isopropylidene)(2,1'-isopropylidene)bis(4,5-benz-1-indenyl)zirconium dichloride, (1,2'-isopropylidene)(2,1'-methylene)bis(4,5-benz-1-indenyl)zirconium dichloride, (1,2'-methylene)(2,1'-methylene)(1-indenyl)(4,5-benz-1-indenyl)zirconium dichloride, (1,2'-isopropylidene)(2,1'-isopropylidene)(1-indenyl)(4,5-benz-1-indenyl)zirconium dichloride, (1,2'-isopropylidene)(2,1'-methylene)(1-indenyl)(4,5-benz-1-indenyl)zirconium dichloride, (1,2'-methylene)(2,1'-methylene)(cyclopentadienyl)(4,5-benz-1-indenyl)zirconium dichloride, (1,2'-isopropylidene)(2,1'-isopropylidene)(cyclopentadienyl)(4,5-benz-1-indenyl)zirconium dichloride, (1,2'-isopropylidene)(2,1'-methylene)(cyclopentadienyl)(4,5-benz-1-indenyl)zirconium dichloride, (1,2'-methylene)(2,1'-methylene)bis(3-cyclopenta(c)phenanthryl)zirconium dichloride, (1,2'-isopropylidene)(2,1'-isopropylidene)bis(3-cyclopenta(c)phenanthryl)zirconium dichloride, (1,2'-isopropylidene)(2,1'-methylene)bis(3-cyclopenta(c)phenanthryl)zirconium dichloride, (1,2'-methylene)(2,1'-methylene)bis(1-cyclopenta(1)phenanthryl)zirconium dichloride, (1,2'-isopropylidene)(2,1'-isopropylidene)bis(1-cyclopenta(1)phenanthryl)zirconium dichloride, and (1,2'-isopropylidene)(2,1'-methylene)bis(1-cyclopenta(1)phenanthryl)zirconium dichloride. In the foregoing, zirconium complexes were exemplified, but corresponding titanium complexes and hafnium complexes may also suitably be used. As such transition metal compound as catalyst components, racemic-form or pseudo racemic-form are preferably used. In such a case, D-isomers or L-isomers may be used. Further, a mixture of a racemic-form and a meso-form may also be used. Thirdly, the present invention provides a polymerization catalyst for producing an aromatic vinyl compound polymer or an aromatic vinyl compound-olefin copolymer, which comprises such a transition metal compound and a cocatalyst and which provides a remarkably high productivity, and an efficient method for producing an aromatic vinyl compound polymer and an aromatic vinyl compound-olefin copolymer, employing such a catalyst. Particularly, it provides a polymerization catalyst for producing an aromatic vinyl compound polymer having isotactic stereoregularity in the polymer structure or an aromatic vinyl compound-olefin copolymer having an isotactic structure, and a method for producing an isotactic aromatic vinyl compound polymer and an aromatic vinyl compound-olefin copolymer having an isotactic structure, employing such a catalyst. As the cocatalyst to be used in the present invention, a cocatalyst which has been used in combination with a transition metal compound as catalyst component, can be used. As such a cocatalyst, aluminoxane (or alumoxane), or a boron compound, is preferably employed. Further, the present invention provides a method for producing an aromatic vinyl compound polymer or an aromatic vinyl compound-olefin copolymer wherein the cocatalyst to be used is an aluminoxane (or alumoxane) of the following formula (3) or (4): wherein R is a C 1-5 alkyl group, a C 6-10 aryl group or hydrogen, m is an integer of from 2 to 100, and the plurality of R may be the same or different, wherein R' is a C 1-5 alkyl group, a C 6-10 aryl group or hydrogen, n is an integer of from 2 to 100, and the plurality of R' may be the same or different. As the aluminoxane, methylalumoxane, ethylalumoxane or triisobutylalumoxane, is preferably employed. Particularly preferred is methylalumoxane. If necessary, a mixture of these different types of alumoxanes, may be employed. Further, such an alumoxane may be used in combination with an alkylaluminum such as trimethylaluminum, triethylaluminum or triisobutylaluminum, or with a halogen-containing alkylaluminum such as dimethylaluminum chloride. Addition of an alkylaluminum to the catalyst is effective for removing substances which hinder polymerization, such as a polymerization inhibitor in styrene, or moisture in the solvent, or for removing adverse effects against the polymerization reaction. However, it is not necessarily required to add an alkylaluminum, if the amount of styrene, solvent, etc. is preliminarily reduced to a level-not to influence the polymerization, by a known method such as distillation, bubbling with a dry inert gas or passing through a molecular sieve, or by increasing the amount of alumoxane to some extent or adding alumoxane in divided portions. In the present invention, a boron compound may be used as a cocatalyst together with the above transition metal compound as catalyst component. The boron compound to be used as a cocatalyst may, for example, be triphenylcarbeniumtetrakis(pentafluorophenyl) borate {trityltetrakis(pentafluorophenyl)borate}, lithium tetra(pentafluorophenyl)borate, tri(pentafluorophenyl)boran, trimethylammoniumtetraphenyl borate, triethylammoniumtetraphenyl borate, tripropylammoniumtetraphenyl borate, tri(n-butyl)ammoniumtetraphenyl borate, tri(n-butyl)ammoniumtetra(p-tolyl)phenyl borate, tri(n-butyl)ammoniumtetra(p-ethylphenyl)borate, tri(n-butyl)ammoniumtetra(pentafluorophenyl)borate, trimethylammoniumtetra(p-tolyl) borate, trimethylammoniumtetrakis-3,5-tetramethylphenyl borate, triethylammoniumtetrakis-3,5-dimethylphenyl borate, tributylammoniumtetrakis-3,5-dimethylphenyl borate, tributylammoniumtetrakis-2,4-dimethylphenyl borate, aniliumtetrakispentafluorophenyl borate, N,N'-dimethylaniliumtetraphenyl borate, N,N'-dimethylaniliumtetrakis(p-tolyl)borate, N,N'-dimethylaniliumtetrakis(m-tolyl)borate, N,N'-dimethylaniliumtetrakis(2,4-dimethylphenyl)borate, N,N'-dimethylaniliumtetrakis(3,5-dimethylphenyl)borate, N,N'-dimethylaniliumtetrakis(pentafluorophenyl)borate, N,N'-diethylaniliumtetrakis(pentafluorophenyl)borate, N,N'-2,4,5-pentamethylaniliumtetraphenyl borate, N,N'-2,4,5-pentaethylaniliumtetrraphenyl borate, di-(isopropyl)ammoniumtetrakispentafluorophenyl borate, di-cyclohexylammoniumtetraphenyl borate, triphenylphosphoniumtetraphenyl borate, tri(methylphenyl)phosphoniumtetraphenyl borate, tri(dimethylphenyl)phosphoniumtetraphenyl borate, triphenylcarbeniumtetrakis(p-tolyl)borate, triphenylcarbeniumtetrakis(m-tolyl)borate, triphenylcarbeniumtetrakis(2,4-dimethylphenyl)borate, triphenylcarbeniumtetrakis(3,5-dimethylphenyl)borate, tropiliumtetrakispentafluorophenyl borate, tropiliumtetrakis(p-tolyl)borate, tropiliumtetrakis(m-tolyl)borate, tropiliumtetrakis(2,4-dimetyylphenyl)borate or tropiliumtetrakis(3,5-dimethylphenyl)borate. Such a boron compound and the above-mentioned organoaluminum compound may be used at the same time. Especially when a boron compound is used as a cocatalyst, addition of an alkylaluminum compound such as triisobutylaluminum is effective for the removal of impurities which adversely affect the polymerization, such as water contained in the polymerization system. Aromatic vinyl compounds to be used in the present invention may, for example, be styrene and various substituted styrenes such as p-methylstyrene, m-methylstyrene, o-methylstyrene, o-t-butylstyrene, p-t-butylstyrene, p-chlorostyrene, o-chlorostyrene, and α-methylstyrene. Further, a compound having a plurality of vinyl groups in one molecule, such as divinylbenzene, may also be mentioned. Industrially preferably, styrene, p-methylstyrene or p-chlorostyrene is used. Particularly preferably, styrene is used. Further, as olefins to be used in the present invention, C 2-20 α-olefins such as ethylene, propylene, 1-butene, 1-hexene, 1-methyl-1-pentene, 1-octene and cyclic olefins such as cyclopentene, norbornene and norbonadiene, may be mentioned. These olefins may be used alone or in combination as a mixture of two or more of them. As such olefins, ethylene and propylene are preferred. In the following description, examples in which ethylene and propylene are used as olefins, will be referred to. For the production of a polymer or a copolymer of the present invention, the olefin, the above exemplified aromatic vinyl compound, the transition metal compound as catalyst component as a metal complex and the cocatalyst are contacted. As to the manner and order for contacting, an optional known method may be employed. For the production of an aromatic vinyl compound polymer of the present invention, the above exemplified aromatic vinyl compound, the transition metal compound as catalyst component as a metal complex and the cocatalyst are contacted. As to the manner and order for contacting, an optional known method may be employed. As a method for the above polymerization or copolymerization, it is possible to employ a method for carrying out the polymerization in a liquid monomer without using any solvent, or a method of using a single solvent or a mixed solvent selected from saturated aliphatic or aromatic hydrocarbons or halogenated hydrocarbons, such as pentane, hexane, heptane, cyclohexane, benzene, toluene, ethylbenzene, xylene, chlorobenzene, chlorotoluene, methylene chloride or chloroform. If necessary, batch polymerization, continuous polymerization, stepwise polymerization, slurry polymerization, preliminary polymerization or gas phase polymerization may be employed. Heretofore, when styrene is employed as a monomer component, it used to be impossible to employ gas phase polymerization in view of its low vapor pressure. However, when a catalyst of the present invention comprising a transition metal compound as catalyst component for polymerization and a cocatalyst, is employed, the copolymerization ability of styrene will be remarkably high, whereby copolymerization is possible even at a low styrene monomer concentration. Namely, copolymerization of an olefin with styrene is possible even under a low styrene partial pressure under a gas phase polymerization condition. In such a case, the transition metal catalyst component for polymerization and the cocatalyst may be used as supported on a suitable known carrier. The polymerization or copolymerization temperature is suitably from -78°C to 200°C. A polymerization temperature lower than -78°C is industrially disadvantageous, and if the temperature exceeds 200°C, decomposition of the metal complex is likely to take place, such being undesirable. Industrially more preferably, the temperature is from -20 to 160°C, particularly from 30 to 160°C. The pressure for copolymerization is suitably from 0.1 to 200 atm, preferably from 1 to 50 atm, industrially particularly preferably, from 1 to 30 atm. When an organoaluminum compound is used as a cocatalyst, it is preferably used in an aluminum atom/complex metal atom ratio of from 0.1 to 100,000, preferably from 10 to 10,000, relative to the metal of the complex. If the ratio is smaller than 0.1, the metal complex can not effectively be activated, and if it exceeds 100,000, such will be economically disadvantageous. When a boron compound is used as a cocatalyst, it is used in an atomic ratio of boron atom/complex metal atom of from 0.01 to 100, preferably from 0.1 to 10, particularly preferably 1. If the atomic ratio is less than 0.01, the metal complex can not effectively be activated, and if it exceeds 100, such is economically disadvantageous. The metal complex and the cocatalyst may be prepared by mixing them outside the polymerization tank, or they may be mixed in the tank during polymerization. Fourthly, the present invention provides an aromatic vinyl compound-olefin copolymer obtained by using the transition metal compound as catalyst component of the present invention or by the method of the present invention. Further, it provides an aromatic vinyl compound-ethylene random copolymer having a head-to-tail chain structure of at least two aromatic vinyl compound units, wherein the aromatic vinyl compound content is from 5 to 99.9 mol%. This copolymer is a novel copolymer and includes an aromatic vinyl compound-ethylene random copolymer obtained by using the transition metal compound as catalyst component of the present invention or by the method of the present invention. However, it is not particularly limited by the transition metal catalyst component or the method of the present invention. In the following, reference is made to a styrene-ethylene random copolymer as an example of the aromatic vinyl compound-ethylene random copolymer of the present invention. However, the present invention is by no means restricted to such a styrene-ethylene copolymer. The structure is determined by a nuclear magnetic resonance method (NMR). The copolymer of the present invention has main peaks at the following positions in 13C-NMR using TMS as standard. Namely, it shows peaks attributable to the main chain methylene and the main chain methine carbon in the vicinity of from 24 to 25 ppm, 27 ppm, 30 ppm, from 34 to 37 ppm, from 40 to 41 ppm and from 42 to 46 ppm, peaks attributable to five atoms not bonded to the polymer chain among phenyl groups in the vicinity of 126 ppm and 128 ppm, and a peak attributable to one carbon bonded to the polymer main chain among phenyl groups in the vicinity of 146 ppm. The styrene-ethylene random copolymer of the present invention is a styrene-ethylene random copolymer having a styrene content of at least 5 and less than 99.9%, more preferably at least 10 and less than 99.9%, by molar fraction, and the stereoregularity of phenyl groups in the alternating structure of styrene and ethylene of the following formula (5) contained in its structure is represented by an isotactic diad index m of larger than 0.75, and the alternating structure index λ of the following formula (i) is smaller than 70 and larger than 1, preferably smaller than 70 and larger than 5: λ = A3/A2×100 Here, A3 is the sum of areas of three peaks a, b and c attributable to the carbons in styrene-ethylene alternating structure of the following formula (5'). Further, A2 is the sum of areas of peaks attributable to the main chain methylene and the main chain methine carbon, as observed within a range of from 0 to 50 ppm by 13C-NMR using TMS as standard: wherein Ph is an aromatic group such as a phenyl group, and x is an integer of at least 2, representing the number of repeating units, wherein Ph is an aromatic group such as a phenyl group, and x is an integer of at least 2, representing the number of repeating units. In the styrene-ethylene random copolymer of the present invention, the stereoregularity of phenyl groups in the alternating copolymer structure of ethylene and styrene being an isotactic structure is meant for a structure wherein the isotactic diad index m (or a meso diad fraction) is more than 0.75, preferably more than 0.85, more preferably more than 0.95. The isotactic diad index m of the alternating copolymer structure of ethylene and styrene can be obtained by the following formula (ii) from an area Ar of the peak attributable to the r structure and an area Am of the peak attributable to the m structure appearing in the vicinity of 25 ppm. m=Am/(Ar+Am) The positions of the peaks may sometimes shift more or less depending upon the measuring conditions or the solvent used. For example, when chloroform-d is used as a solvent, and TMS is used as standard, the peak attributable to the r structure appears in the vicinity of from 25.4 to 25.5 ppm, and the peak attributable to the m structure appears in the vicinity of from 25.2 to 25.3 ppm. Further, when 1,1,2,2-tetrachloroethane-d2 is used as a solvent, and the center peak (shift value of 73.89 ppm from TMS standard) of the triplet of the 1,1,2,2-tetrachloroethane-d2 is used as standard, the peak attributable to the r structure appears in the vicinity of from 25.3 to 25.4 ppm, and the peak attributable to the m structure appears in the vicinity of from 25.1 to 25.2 ppm. Here, the m structure represents a meso diad structure, and the r structure represents a racemic diad structure. In the styrene-ethylene random copolymer of the present invention, a peak attributable to the r structure of the alternating structure of ethylene and styrene is not substantially observed. The chain structure of a head-to-tail bond of styrene units contained in the styrene-ethylene random copolymer of the present invention is a chain structure of at least two styrenes, preferably a chain structure of at least three styrenes, which can be represented by the following structure: wherein n is an optional integer of at least 2, and Ph is aromatic group such as phenyl group. The chain structure wherein two styrene units are bonded head-to-tail, gives peaks in the vicinity of from 42.4 to 43.0 ppm and from 43.7 to 44.5 ppm in the 13C-NMR measurement using TMS as standard and 1,1,2,2-tetrachloroethane-d2 as a solvent. The chain structure in which at least three styrene units are bonded head-to-tail gives peaks also in the vicinity of from 40.7 to 41.0 ppm and from 43.0 to 43.6 ppm-in a similar measurement. Accordingly, the chain structure in which at least two styrene units bonded head-to-tail gives a peak in the vicinity of from 40 to 45 ppm in a similar measurement. On the other hand, in the conventional so-called pseudo random copolymer, no head-to-tail chain structure of styrene can be found even in the vicinity of 50 mol% at which the styrene content is maximum. Further, even if homopolymerization of styrene is attempted by using a catalyst for the preparation of a pseudo random copolymer, no polymer is obtainable. Depending upon e.g. the polymerization condition, an extremely small amount of an atarctic styrene homopolymer may sometimes be obtained. However, this is considered to have been formed by radical polymerization or cation polymerization by coexisting methylalumoxane or an alkylaluminum included therein. Further, in the styrene-ethylene random copolymer of the present invention, the stereoregularity of phenyl groups in the head to tail chain structure of styrene units is isotactic. The stereoregularity of phenyl groups in the head to tail chain structure of styrene units being isotactic, is meant for a structure wherein the isotactic diad index ms (or a meso diad fraction) is larger than 0.5, preferably at least 0.7, more preferably at least 0.8. The stereoregularity of the chain structure of styrene units is determined by the peak position of methylene carbon in the vicinity of from 43 to 44 ppm as observed by 13C-NMR and by the peak position of the main chain proton as observed by 1H-HMR. According to U.S. Patent 5,502,133, methylene carbon of an isotactic polystyrene chain structure appears in the vicinity of from 42.9 to 43.3 ppm, but methylene carbon of a syndiotactic polystyrene chain structure appears in the vicinity of from 44.0 to 44.7 ppm. The positions of the sharp peak of methylene carbon of the syndiotactic polystyrene and the broad peak at from 43 to 45 ppm of an atarctic polystyrene are close to or overlap the positions of peaks with relatively low intensity of other carbon of the styrene-ethylene random copolymer of the present invention. However, in the present invention, a strong methylene carbon peak is observed from 42.9 to 43.4 ppm, but no clear peak is observed in the vicinity of from 44.0 to 44.7. Further, according to U.S. Patent 5,502,133 and the Comparative Examples of the present invention, the peaks attributable to the main chain methylene and methine proton in 1H-NMR, are observed at from 1.5 to 1.6 ppm and from 2.2 to 2.3 ppm in the case of an isotactic polystyrene and at from 1.3 to 1.4 ppm and from 1.8 to 1.9 ppm in the case of a syndiotactic polystyrene. With the copolymer of the present invention, peaks are observed at from 1.5 to 1.6 ppm and at 2.2 ppm, and the result of this NMR analysis indicates that the styrene chain in the copolymer of the present invention has isotactic stereoregularity. The isotactic diad index ms of the chain structure of styrene units can be obtained by the following formula from the respective peaks of methylene carbon in the styrene chain structure by the 13C-NMR measurement or the main chain methylene and methine proton by the 1H-NMR measurement. Namely, it can be obtained by the following formula (iii) from an area Ar' of the peak attributable to the syndiotactic diad structure (r structure) of each peak and an area Am' of the peak attributable to the isotactic diad structure (m structure). ms=Am'/(Ar'+Am') The positions of the peaks may sometimes shift more or less depending upon the measuring conditions or the solvent used. The random copolymer in the present invention is a copolymer containing a chain structure wherein styrene units are bonded head-to-tail, a chain structure wherein ethylene units are bonded to one another and a structure in which styrene units and ethylene units are bonded. The proportions of these structures contained in the copolymer vary depending upon the content of styrene or polymerization conditions such as the polymerization temperature. As the styrene content decreases, the proportion of the chain structure in which styrene units are bonded head-to-tail, decreases. For example, in a case of a copolymer wherein the styrene content is not higher than about 20 mol%, it is difficult to directly observe a peak attributable to the chain structure wherein styrene units are bonded head-to-tail, by the usual 13C-NMR measurement. However, it is evident that the chain structure in which styrene units are bonded head-to-tail, is present in the copolymer, although the amount may be small, even if the styrene content is not higher than 20 mol%, since it is possible to produce a homopolymer having stereoregularity under high catalytic activity by homopolymerization of styrene by using the transition metal catalyst component of the present invention or by the method of the present invention, i.e. it is essentially possible to form a chain structure in which styrene units are bonded head-to-tail, and since in the copolymer, the proportion of the chain structure in which styrene units are bonded head-to-tail, continuously changes corresponding to the styrene content of from 20 to 99 mol% at least by the 13C-NMR method. It is possible to observe the chain structure wherein styrene units are bonded head-to-tail, in the copolymer having a styrene content of not higher than 20 mol%, by such a means as the 13C-NMR analysis using a styrene monomer enriched with 13C. The same applies to the chain structure of ethylene units. It is known that peaks of methylene carbon of the structure derived from inversion of styrene in a conventional pseudo random copolymer having no stereoregularity, are present in two regions of from 34.0 to 34.5 ppm and from 34.5 to 35.2 ppm (for example, Polymer Preprints, Japan, 42 , 2292 (1993)). With the styrene-ethylene random copolymer of the present invention, a peak attributable to methylene carbon of an inversion bond structure derived from styrene is observed in a region of from 34.5 to 35.2 ppm, but no substantial peak is observed at from 34.0 to 34.5 ppm. This indicates one of the characteristics of the copolymer of the present invention and indicates that high stereoregularity of phenyl groups is maintained even with an inversion bond structure of the following formula derived from styrene. The weight average molecular weight of the styrene-ethylene random copolymer of the present invention is at least 60,000, preferably at least 80,000, particularly preferably at least 180,000, when the styrene content is at least 5 mol% and less than 20 mol%, and at least 30,000, preferably at least 40,000, more preferably at least 100,000, particularly preferably at least 220,000, when the styrene content is at least 20 mol% and less than 55 mol%, and at least 30,000, preferably at least 40,000, when the styrene content is at least 55 mol% and at most 99.9 mol%, thus being a practical high molecular weight. The molecular weight distribution (Mw/Mn) is at most 6, preferably at most 4, particularly preferably at most 3. Here, the weight average molecular weight is a molecular weight as calculated as polystyrene, obtained by GPC using standard polystyrene. The same applies in the following description. The styrene-ethylene random copolymer of the present invention is characterized in that it has a highly stereoregular alternating structure of ethylene and styrene in combination with various structures such as ethylene chains having various lengths, inversion of styrene and head to tail chains of styrene having various length. Further, with the styrene-ethylene random copolymer of the present invention, the proportion of the alternating structure can be variously changed by the styrene content in the copolymer within a range of λ of the above formula being more than 1 and less than 70. The stereoregular alternating structure is a crystallizable structure. Accordingly, the copolymer of the present invention can be made to have various properties in the form of a polymer having a crystalline, non-crystalline, or partially or microcrystalline structure, by controlling the St content or the crystallinity by a suitable method. The value λ being less than 70 is important in order to impart significant toughness and transparency to a crystalline polymer, or to obtain a partially crystalline polymer, or to obtain a non-crystalline polymer. As compared with a conventional styrene-ethylene copolymer having no stereoregularity or no styrene chains, the copolymer of the present invention is improved in various properties such as the initial tensile modulus, hardness, breaking strength and solvent resistance in various St content regions at various degrees of crystallinity and thus exhibits characteristic physical properties as a novel crystalline resin, a thermoplastic elastomer or a transparent soft resin. Further, by changing the styrene content, the glass transition point can be changed within a wide range from -50°C to 100°C. Among copolymers of the present invention, a copolymer consisting mainly of a chain structure of styrene units and an alternating structure of styrene units and ethylene units and having a styrene content of more than 50 mol%, has high transparency and a high glass transition temperature and exhibits a high initial tensile modulus and excellent physical properties as a plastic, since ethylene chains are little or very little. Further, the alternating structure and a small amount of ethylene chains are relatively uniformly present in the chain structure, whereby the copolymer is excellent in impact resistance and shows excellent toughness. Within a styrene content from 10 mol% to 75 mol%, preferably from 15 mol% to 60 mol%, the copolymer has crystallizability due to the stereoregularity of the alternating structure and will be a copolymer having a partially or microcrystalline structure, whereby it is capable of exhibiting physical properties as a thermoplastic elastomer in the vicinity of the glass transition temperature or at a higher temperature. Further, the styrene chain structure has an isotactic stereoregularity, whereby the copolymer is crystallizable, and can be crystallized by a common crystallization treatment. The styrene-ethylene random copolymer of the present invention can have a melting point of from about 50 to 130°C (by DSC) within a range of a styrene content of from 10 to 75 mol%. Further, at a styrene content of at least 90 mol%, it may have a melting point of from about 100 to 240°C attributable to an isotactic polystyrene chain structure. The heat of crystal fusion is at a level of from 1 to 50 J/g in either case. Such heat of crystal fusion and melting point by DSC can be changed to some extent by e.g. pretreatment conditions. On the other hand, a conventional styrene-ethylene copolymer (a pseudo random copolymer) having no stereoregularity or no styrene chain, has a crystal structure similar to polyethylene at a low styrene content, as shown in literature ANTEC, 1634 (1996), but with an increase of the styrene content in the copolymer, the melting point and the crystallinity will rapidly decrease, and at a styrene content of about 15 mol%, the melting point becomes as low as about room temperature. Further, at a styrene content of from about 15 or 20 mol% to less than 50 mol%, the copolymer will be amorphous having no melting point. The styrene-ethylene random copolymer of the present invention which contains basically no dissolvable plasticizer or halogen, has a basic characteristic that it is highly safe. Further, depending upon the polymerization conditions, etc., a small amount of an atarctic homopolymer formed by polymerization of an aromatic vinyl compound by heat, radical or cation polymerization, may sometimes be contained, but such an amount should be less than 10 wt% of the total. Such a homopolymer can be removed by extraction with a solvent, but the copolymer may be used as it contains such a homopolymer, provided that there will be no particular problem from the viewpoint of the physical properties. The copolymer of the present invention has the following characteristics at the respective styrene contents. The copolymer with a styrene content of from 5 to 10 mol% has high tensile strength and transparency, is flexible and shows a nature as a platomer or elastomer. The copolymer with a styrene content of from 10 to 25 mol% has high tensile strength, elongation, transparency, flexibility and resiliency and shows a nature as an elastomer. The copolymers'having the foregoing compositions are useful alone or in the form of an alloy of the copolymers having different styrene contents or in the form of an alloy with a polyolefin such as polypropylene, as a stretch film for packaging. The copolymer with a styrene content of from 50 to 99.9 mol% having a microcrystalline structure or a low crystallinity, is a plastic having high transparency and has a high shrinking property at a temperature of at least the glass transition point and high dimensional stability at a temperature of not higher than the glass transition temperature, and thus it is useful as a shrinkable film for packaging. Further, even if a fixed shape formed by once heating at a temperature higher than the melting point and then quenching to a temperature below the glass transition temperature, is deformed under a temperature condition of higher than the glass transition temperature and lower than the melting point and cooled to a temperature lower than the glass transition temperature to fix the deformed shape, if it is heated again to a temperature higher than the glass transition temperature and lower than the melting point, it recovers the initial shape. Namely, the copolymer has a shape memory property. The copolymer with a styrene content of from 5 to 50 mol% is suitably employed for various applications as a substitute for soft polyvinyl chloride, in the form of an alloy with a polyolefin such as polypropylene or polyethylene, or with polystyrene or other resin, or in the form of a partially crosslinked composition. Further, the copolymer with this composition is useful as a compatibilizing agent for a polyolefin and a styrene resin, as an additive to a styrene resin or a polyolefin resin, as a modifier for rubber, as a component for an adhesive, or as bitumen (an additive to asphalt). By changing the styrene content, the glass transition point of the copolymer of the present invention can be optionally changed within a range of from -50 to 100°C, and the copolymer has a large tanδ peak in the viscoelasticity spectrum and thus is useful as a vibration preventing material effective for a wide temperature range. With the copolymer having a styrene content of about 50 mol%, it is relatively easy to increase the crystallinity as compared with copolymers with other ranges of the styrene content, and it exhibits a high initial elastic modulus although it is opaque, and thus is useful as a novel partially crystalline plastic. As a means for increasing the crystallinity, it is possible to adopt a means such as annealing, addition of a nucleating agent or alloying with a polymer having low Tg (such as wax). In the foregoing, a styrene-ethylene random copolymer has been described as a typical example of the aromatic vinyl compound-ethylene random copolymer of the present invention. However, the above description is generally applicable to the aromatic vinyl compound-ethylene random copolymer employing the above aromatic vinyl compound. The present invention also provides an aromatic vinyl compound-propylene random copolymer wherein the aromatic vinyl compound content is from 5 to 99.9 mol%. This copolymer is a novel copolymer and includes an aromatic vinyl compound-propylene random copolymer obtained by using the transition metal compound as catalyst component of the present invention, or by the method of the present invention. However, such a copolymer is not restricted by the transition metal compound or the method of the present invention. Now, a styrene-propylene random copolymer will be described as an example of the copolymer of the present invention. The styrene-propylene random copolymer in the present invention is a copolymer having an aromatic vinyl compound content of from 5 to 99.9 mol%. Further, it is an aromatic vinyl compound-propylene random copolymer characterized in that it has both chain structures of aromatic vinyl compound units and propylene units. Further, it is an aromatic vinyl compound-propylene random copolymer, wherein the stereoregularity of the chain structures of the aromatic vinyl compound units and/or the propylene units, is isotactic. The aromatic vinyl compound-olefin random copolymer of the present invention has a weight average molecular weight of at least 1,000, preferably at least 10,000, taking into consideration the physical properties as a copolymer (aromatic vinyl compound-ethylene random copolymer, is as described above). The molecular weight distribution(Mw/Mn) is at most 6, preferably at most 4, particularly preferably at most 3. The aromatic vinyl compound-olefin random copolymer of the present invention is not necessarily required to be a pure copolymer, and other structures may be contained, or any other monomer among the above-mentioned α-olefins, aromatic vinyl compounds, and conjugated dienes such as butadiene, may be copolymerized, so long as the structure and the stereoregularity are within the above-mentioned ranges. Further, depending upon the polymerization conditions, etc., a small amount of an atarctic homopolymer formed by polymerization of an aromatic vinyl compound by heat, radical or cation polymerization, may sometimes be contained, but such an amount should be less than 10 wt% of the total. Such a homopolymer can be removed by extraction with a solvent, but the copolymer may be used as it contains such a homopolymer, provided that there will be no particular problem from the viewpoint of the physical properties. Further, for the purpose of improving the physical properties, it may be blended with other polymers. Further, copolymers of the present invention having different styrene contents may be blended. Fifthly, the present invention provides a method for producing an aromatic vinyl compound polymer employing a transition metal compound of the above-mentioned formula (1) and cocatalyst. The stereoregularity of the aromatic vinyl compound polymer obtained by the method of the present invention is represented by an isotactic pentad index (mmmm) of at least 0.70, preferably at least 0.80, more preferably at least 0.90. The isotactic diad index can be obtained from a peak attributable to carbon (PhCl) of a phenyl group bonded to the main chain of the polymer in the 13C-NMR measurement. Namely, it is obtained from the proportion of the PhCl carbon peak area attributable to the mmmm structure in the total of PhCl carbon peak areas. The PhCl carbon peak attributable to the mmmm structure appears in the vicinity of 146.3 ppm when 1,1,2,2-tetrachloroethane-d2 is used as a solvent, and the triplet center peak (73.89 ppm) of 1,1,2,2-tetrachloroethane-d2 is used as standard. The isotactic aromatic vinyl compound polymer obtained in the present invention has a weight average molecular weight of at least 1,000, preferably at least 10,000 taking into consideration the physical properties as a crystalline polymer. The molecular weight distribution (Mw/Mn) is at most 6, preferably at most 4, particularly preferably at most 3. By the method of the present invention, it is possible to obtain an isotactic aromatic vinyl compound polymer having a high stereoregularity under high catalytic activities with little formation of atactic polystyrene as a byproduct. Sixthly, the present invention provides an aromatic vinyl compound-olefin alternating copolymer, preferably an aromatic vinyl compound-ethylene alternating copolymer, consisting mainly of an alternating structure. This copolymer can be obtained by using the transition metal compound as catalyst component of the present invention, or by the method of the present invention. The aromatic vinyl compound-ethylene alternating copolymer obtainable by the present invention, is an aromatic vinyl compound-ethylene alternating copolymer characterized in that the stereoregularity of phenyl groups in the alternating structure of ethylene and an aromatic vinyl compound, is represented by an isotactic diad index m which is at least 0.95, and the alternating structure index λ given by the above formula (i) is at least 70. The isotactic diad (meso diad) index m of the alternating structure of ethylene and styrene in this copolymer, as an example of the aromatic vinyl compound-ethylene alternating copolymer of the present invention, can be obtained by the above-mentioned method employing the above formula (ii). The weight average molecular weight obtained as calculated as standard polystyrene, of the aromatic vinyl compound-ethylene alternating copolymer of the present invention, is preferably at least 10,000, taking into consideration the physical properties as a crystalline plastic. The molecular weight distribution (Mw/Mn) is at most 6, preferably at most 4, particularly preferably at most 3. This copolymer has an aromatic vinyl compound content of from 46 to 54 mol% and consists mainly of an alternating structure of ethylene and the aromatic vinyl compound, which has high stereoregularity. It is characterized in that it further contains small amounts of various structures, such as ethylene chains of various lengths, heterogeneous bonds of the aromatic vinyl compound and chains of the aromatic vinyl compound, in a proportion not higher than a certain level. The copolymer of the present invention has a high proportion of the alternating structure and high stereoregularity due to the alternating structure and accordingly has characteristics such as high crystallinity, high melting point and a high crystallization speed. The melting point of the copolymer obtainable by the DSC measurement is at least 130°C and less than 210°C preferably at least 150°C and less than 210°C. The copolymer of the present invention is capable of exhibiting high physical properties as a crystalline or partially crystalline polymer. Therefore, it is expected to open up a novel application of a crystalline plastic as a substitute for polypropylene, a PET resin, nylon, etc. For the production of the alternating copolymer of the present invention, the polymerization temperature is usually from -20 to +40°C. Now, the present invention will be described in further detail with reference to Examples. However, it should be understood that the present invention is by no means restricted to such specific Examples. In the following description, Cp represents a cyclopentadienyl group, Ind a 1-indenyl group, BInd a 4,5-benz-1-indenyl group, Flu a 9-fluorenyl group, Me a methyl group, Et an ethyl group, tBu a tertiary butyl group, and Ph a phenyl group. In the accompanying drawings: Figure 1 is a graph showing the productivity of the polymer per catalyst in each Example or Comparative Example. Figure 2 is a GPC chart of the styrene-ethylene random copolymer obtained in Example 2. Figure 3 is a DSC chart of the styrene-ethylene random copolymer obtained in Example 2. Figure 4 is a 1H-NMR chart of the styrene-ethylene random copolymer obtained in Example 3. Figure 5 is a 1H-NMR chart of the styrene-ethylene random copolymer obtained in Example 4. Figure 6 is a 13C-NMR chart of the styrene-ethylene random copolymer obtained in Example 3. Entire spectrum Figure 7 is a 13C-NMR chart of the styrene-ethylene random copolymer obtained in Example 3. Methine-methylene region Figure 8 is a 13C-NMR chart of the styrene-ethylene random copolymer obtained in Example 4. Entire spectrum Figure 9 is a 13C-NMR chart of the styrene-ethylene random copolymer obtained in Example 4. Methine-methylene region Figure 10 is a 13C-NMR chart of the styrene-ethylene random copolymer obtained in Example 6. Entire spectrum Figure 11 is a 13C-NMR chart of the styrene-ethylene random copolymer obtained in Example 6. Methine-methylene region Figure 12 is a 13C-NMR chart of the styrene-ethylene random copolymer obtained in Example 9. Entire spectrum Figure 13 is a 13C-NMR chart of the styrene-ethylene random copolymer obtained in Example 9. Methine-methylene region Figure 14 is a 13C-NMR chart of the styrene-ethylene random copolymer obtained in Example 10. Entire spectrum Figure 15 is a 13C-NMR chart of the styrene-ethylene random copolymer obtained in Example 10. Methine-methylene region Figure 16 is a 13C-NMR chart of the styrene-ethylene random copolymer obtained in Example 12. Entire spectrum Figure 17 is a 13C-NMR chart of the styrene-ethylene random copolymer obtained in Example 12. Methine-methylene region Figure 18 is a 13C-NMR chart of the styrene-ethylene random copolymer obtained in Example 13. Entire spectrum Figure 19 is a 13C-NMR chart of the styrene-ethylene random copolymer obtained in Example 13. Methine-methylene region Figure 20 is a 13C-NMR chart of a styrene-ethylene pseudo random copolymer obtained in Comparative Example 1. Entire spectrum Figure 21 is a 13C-NMR chart of the styrene-ethylene pseudo random copolymer obtained in Comparative Example 1. Methine-methylene region Figure 22 is a 13C-NMR chart of a styrene-ethylene pseudo random copolymer obtained in Comparative Example 3. Entire spectrum Figure 23 is a 13C-NMR chart of the styrene-ethylene pseudo random copolymer obtained in Comparative Example 3. Methine-methylene region Figure 24 shows 13C-NMR charts in the vicinity of 45 ppm (methine carbon peak). Figure 25 shows 13C-NMR charts in the vicinity of 25 ppm (alternating structure peak). Figure 26 shows X-ray diffraction patterns of the copolymers obtained in Examples 10 and 14. Figure 27 is a GPC chart of the styrene-propylene random copolymer obtained in Example 15. Figure 28 is a DSC chart of the styrene-propylene random copolymer obtained in Example 15. Figure 29 is a 13C-NMR chart of the styrene-propylene random copolymer obtained in Example 15. Methine-methylene-methyl region Figure 30 is a 13C-NMR chart of the styrene-propylene random copolymer obtained in Example 15. Phenyl C1 region Figure 31 is a 13C-NMR chart of the styrene-propylene random copolymer obtained in Example 17. Methine-methylene-methyl region Figure 32 is a 13C-NMR chart of the styrene-propylene random copolymer obtained in Example 17. Phenyl C1 region Figure 33 is a 13C-NMR chart of the styrene-propylene random copolymer obtained in Example 18. Methine-methylene-methyl region Figure 34 is a 13C-NMR chart of the styrene-propylene random copolymer obtained in Example 18. Phenyl C1 region Figure 35 is a 13C-NMR chart of the styrene polymer obtained in Example 19. Figure 36 is a DSC chart of the styrene polymer obtained in Example 19. Figure 37 is an X-ray diffraction pattern of the styrene polymer obtained in Example 19. Figure 38 is a 1H-NMR spectrum of the styrene-ethylene alternating copolymer obtained in Example 21. Figure 39 is a 13C-NMR spectrum of the styrene-ethylene alternating copolymer obtained in Example 21. Entire spectrum Figure 40 is a 13C-NMR spectrum of the styrene-ethylene alternating copolymer obtained in Example 21. Methine-methylene region Figure 41 is a GPC chart of the styrene-ethylene alternating copolymer obtained in Example 21. Figure 42 is a DSC chart of the styrene-ethylene alternating copolymer obtained in Example 22. Figure 43 is an X-ray diffraction pattern of the styrene-ethylene alternating copolymer obtained in Example 21. Figure 44 is a 13C-NMR spectrum of the styrene-ethylene random copolymer obtained in Example 23. Entire spectrum Figure 45 is a 13C-NMR spectrum of the styrene-ethylene random copolymer obtained in Example 23. Methine-methylene region Figure 46 is a 13C-NMR spectrum of the styrene-ethylene random copolymer obtained in Example 23. In the vicinity of 25 ppm. The analyses of the copolymers obtained in the respective Examples and Comparative Examples were carried out by the following methods. The 13C-NMR spectrum was measured using TMS as standard, by using α-500 manufactured by Nippon Denshi Kabushiki Kaisha and using a chloroform-d solvent or a 1,1,2,2-tetrachloroethane-d2 solvent. Here, the measurement using TMS as standard is the following measurement. Firstly, using TMS as standard, the shift value of the center peak of the triplet 13C-NMR peak of 1,1,2,2-tetrachloroethane-d2 was determined. Then, the copolymer was dissolved in the tetrachloroethane, and the 13C-NMR was measured, and each peak shift value was calculated using the triplet center peak of the tetrachloroethane as standard. The shift value of the triplet center peak of the tetrachloroethane was 73..89 ppm. The 13C-NMR spectrum measurement for quantitative analysis of peak areas, was carried out by a proton gate decoupling method having NOE erased, by using pulses with a pulse width of 45° and a repeating time of 5 seconds as standard. When the measurement was carried out under the same conditions except that the repeating time was changed to 1.5 seconds, the measured values of peak areas of the copolymer agreed to the values obtained in the case where the repeating time was 5 seconds, within a measurement error range. The styrene content in the copolymer was determined by 1H-NMR. As the apparatus, α-500 manufactured by Nippon Denshi Kabushiki Kaisha and AC-250 manufactured by BRUKER Co. were used. The determination was made by comparing the intensity of the peak (6.5 to 7.5 ppm) attributable to the proton of a phenyl group and the proton peak (0.8 to 3 ppm) attributable to a methylene, methine and methyl group, measured by using TMS as standard and chloroform-d or 1,1,2,2-tetrachloroethane-d2 as a solvent. The molecular weights in Examples are obtained by GPC (gel permeation chromatography) as calculated as standard polystyrene. A copolymer soluble in THF at room temperature, was measured by means of HLC-8020, manufactured by TOSOH CORPORATION using THF as a solvent. A copolymer insoluble in THF at room temperature, was measured at 135°C by means of 150CV apparatus manufactured by Waters Co. and using 1,2,4-trichlorobenzene as a solvent. The DSC measurement was carried out by using DSC200, manufactured by Seiko Denshi K.K. in a nitrogen stream at a temperature raising rate of 10°C/min. The X-ray diffraction was measured by means of MXP-18 model high power X-ray diffraction apparatus, source Cu rotating anode (wavelength: 1.5405 Å), manufactured by Mac Science Company. TEST EXAMPLES Preparation A of transition metal compound Rac-dimethylmethylenebis(4,5-benz-1-indenyl)zirconium dichloride (another name: rac-isopropylidenebis(4,5-benz-1-indenyl)zirconium dichloride, hereinafter referred to as rac{BInd-C(Me) 2 -Bind}ZrCl 2 ) of the following formula was prepared by the following method. 4,5-Benzindene was prepared in accordance with Organometallics, 13 , 964 (1994). A-1 Preparation 1,1-isopropylidene-4,5-benzindene Preparation of 1,1-isopropylidene-4,5-benzindene was carried out with reference to the preparation of 6,6-diphenylfulvene disclosed in Can, J. Chem. 62 , 1751 (1984). However, as starting materials, acetone was used instead of benzphenone, and 4,5-benzindene was used instead of cyclopentadiene. A-2 Preparation of isopropylidenebis 4,5-benz-1-indene In an Ar atmosphere, 21 mmol of 4,5-benzindene was dissolved in 70 ml of THF, and an equivalent amount of BuLi was added thereto at 0°C, followed by stirring for 3 hours. THF having 21 mmol of 1,1-isopropylidene-4,5-benzindene dissolved therein, was added thereto, followed by stirring at room temperature overnight. Then, 100 ml of water and 150 ml of diethyl ether were added thereto, followed by shaking, and the organic layer was separated and washed with a saturated sodium chloride aqueous solution and then dried over sodium sulfate. The solvent was distilled off under reduced pressure. The obtained yellow solid was washed with hexane and dried to obtain 3.6 g of isopropylidenebis 4,5-benz-1-indene. The yield was 46%. From the 1H-NMR spectrum measurement, it was found to have peaks at 7.2-8.0 ppm (m,12H), 6.65 ppm (2H), 3.75 ppm (4H), and 1.84 ppm (6H). The measurement was carried out using TMS as standard and CDCl 3 as a solvent. A-3 Preparation of rac-dimethylmethylenebis(4,5-benz-1-indenyl)zirconium dichloride In an Ar atmosphere, 7.6 mmol of isopropylidenebis 4,5-benz-1-indene and 7.2 mmol of zirconium tetrakisdimethylamide (Zr(NMe 2 ) 4 ) were charged together with 50 ml of toluene, followed by stirring at 130°C for 10 hours. Toluene was distilled off under reduced pressure, and 100 ml of methylene chloride was added thereto, and the mixture was cooled to -78°C. Then, 14.4 mmol of dimethylamine hydrochloride was slowly added thereto, and the temperature was slowly raised to room temperature, followed by stirring for 2 hours. After distilling off the solvent, the obtained solid was washed with pentane and then with a small amount of THF to obtain 0.84 g of rac-dimethylmethylenebis(4,5-benz-1-indenyl)zirconium dichloride of yellow orange color of the following formula. The yield was 21%. From the 1H-NMR spectrum measurement, it was found to have peaks at 8.01 ppm (m,2H), 7.75 ppm (m,2H), 7.69 ppm (d,2H), 7.48-7.58 ppm (m,4H), 7.38 ppm (d,2H), 7.19 ppm (d,2H), 6.26 ppm (d,2H) and 2.42 ppm (s,6H). The measurement was carried out using TMS as standard and CDCl 3 as a solvent. The elemental analysis was carried out by elemental analysis apparatus 1108 model (manufactured by Fysons Co., Italy), whereby the results being C63.86% and H3.98% were obtained. The theoretical values were C65.39% and H4.16%. Preparation B of transition metal compound as catalyst component Rac-dimethylmethylene(1-indenyl)(4,5-benz-1-indenyl)zirconium dichloride (another name: rac-isopropylidene(1-indenyl)(4,5-benz-1-indenyl)zirconium dichloride, hereinafter referred to as rac{Ind-C(Me) 2 -BInd}ZrCl 2 ) was prepared by the following method. B-1 Preparation of isopropylidene(1-indene)(4,5-benz-1 -indene) In an Ar atmosphere, 14 mmol of indene was dissolved in 50 ml of THF, and an equivalent amount of BuLi was added at 0°C, followed by stirring for 10 hours. Then, 10 ml of THF having 13 mmol of 1,1-isopropylidene-4,5-benzindene dissolved therein, was added thereto, followed by stirring at room temperature overnight. Then, 50 ml of water and 100 ml of diethyl ether were added, followed by shaking, and the organic layer was separated, washed with a saturated sodium chloride aqueous solution and dried over sodium sulfate. Then, the solvent was distilled off under reduced pressure. The residue was further purified by column chromatography to obtain 2.5 g of isopropylidene (1-indene)(4,5-benz-1-indene). The yield was 59%. B-2 Preparation of rac-dimethylmethylene(1-indenyl)(4,5-benz-1-indenyl)zirconium dichloride In an Ar atmosphere, 6.5 mmol of isopropylidene (1-indene)(4,5-benz-1-indene) and 6.5 mmol of zirconium tetrakisdimethylamide {Zr(NMe 2 ) 4 } were charged together with 40 ml of toluene, followed by stirring at 130°C for 10 hours. Then, toluene was distilled off under reduced pressure, and 100 ml of methylene chloride was added thereto, and the mixture was cooled to -78°C. Then, 13 mmol of dimethylamine hydrochloride was slowly added thereto, and the temperature was slowly raised to room temperature, followed by stirring for 2 hours. Then, the solvent was distilled off, and the obtained solid was washed with pentane and then with a small amount of methylene chloride to obtain 0.76 g of rac-dimethylmethylene(1-indenyl)(4,5-benz-1-indenyl)zirconium dichloride of orange color. The yield was 24%. From the 1H-NMR spectrum measurement, it was found to have peaks at 7.05-8.04 ppm (m,10H) (provided a peak at 7.17 ppm is excluded), 7.17 ppm (d,H), 6.73 ppm (d,H), 6.25 ppm (d,H), 6.18 ppm (d,H), 2.41 ppm (m,3H), and 2.37 ppm (m,3H). The measurement was carried out using TMS as standard and CDCl 3 as a solvent. Preparation C transition metal compound as catalyst component Rac-dimethylmethylenebis(4,5-benz-1-indenyl)zirconiumbisdimethylamide (another name: rac-isopropylidenebis(4,5-benz-1-indenyl)zirconiumbisdimethylamide, hereinafter referred to as rac{BInd-CMe 2 -BInd}Zr(NMe 2 ) 2 ) of the following formula and meso-dimethylmethylenebis(4,5-benz-1-indenyl)zirconiumbisdimethylamide (another name: meso-isopropylidenebis(4,5-benz-1-indenyl)zirconiumbisdimethylamide, hereinafter referred to as meso{BInd-CMe 2 -BInd}Zr(NMe 2 ) 2 ) were prepared as follows. Into a 50 ml three-necked flask, a ligand (0.47 g, 1.25 mmol) was introduced and dissolved in 30 ml of toluene. Then, Zr(NMe 2 ) 4 (0.334 g, 1.25 mmol) was added thereto, and the mixture was heated to 100°C in an Ar stream and stirred for 3 days. The solvent was distilled off from the product, and the residue was washed with pentane to obtain a pale brown powder. From the NMR measurement, it was found to be a mixture of a composition comprising 28% of a racemic-form, 13% of a meso-form and 59% of the ligand. rac-form: 1 H-NMR(C6D6,TMS)δ: 1.70(s,12H,NMe2), 1.77(s,6H, CMe2), 5.91(d,2H,BIndC5), 6.73(d,2H,BIndC5), 6.8-7.7(m,12H,aromatic) meso-form: 1 H-NMR(C6D6,TMS)δ: 0.75(s,6H,NMe2), 1.50(s,3H,CMe2), 2.03(s,3H,CMe2), 2.71(s,6H,NMe2), 5.55(d,2H,BIndC5), 6.61(d,2H,BIndC5), 6.8-7.7(m,12H,aromatic) Preparation of styrene-ethylene random copolymers EXAMPLE 1 Into an autoclave having a capacity of 120 ml and equipped with a magnetic stirrer, which was evacuated and then filled with ethylene, 10 ml of styrene and 8.4 µmol, based on Al atom, of methyl alumoxane (MMAO-3A, manufactured by TOSOH-AKZO K.K.) were charged. While magnetically stirring at room temperature, 16 ml of a toluene solution containing 8.4 µmol of the catalyst obtained in "Preparation B of transition metal catalyst component", rac{BInd-C(Me) 2 -Ind}ZrCl 2 , and 0.84 mmol of triisobutylaluminum, was quickly charged by a syringe, and ethylene was immediately introduced to raise the pressure to a total pressure of 0.6 MPa (5 kg/cm 2 G). In 4 minutes after charging the catalyst, the inner temperature rised to 46°C by polymerization heat, but after 5 minutes, the temperature started to drop. While maintaining the pressure at a level of 5 kg/cm 2 G, polymerization was carried out for 1 hour. The polymerization solution was put into a large excess amount of dilute hydrochloric acid/methanol liquid to precipitate the polymer, which was dried under vacuum at 78°C for 8 hours, to obtain 5 g of the polymer. EXAMPLE 2 Polymerization was carried out by using an autoclave having a capacity of 10 lit. and equipped with a stirrer and a jacket for heating/cooling. 800 ml of dry toluene and 4,000 ml of dry styrene were charged, and the inner temperature was raised to 50 °C, followed by stirring. About 100 l of nitrogen was used for bubbling to purge the interior of the system, and then 8.4 mmol of triisobutylaluminum and 84 mmol, based on Al, of methylalumoxane (MMAO-3A, manufactured by TOSOH-AKZO K.K.) were added thereto. Ethylene was immediately introduced, and after the pressure was stabilized at 0.2 MPa (1 kg/cm 2 G), about 50 ml of a toluene solution containing 21 µmol of the catalyst obtained in "Preparation A of transition metal catalyst component", rac-dimethylmethylenebis(4,5-benz-1-indenyl)zirconium dichloride, and 0.84 mmol of triisobutylaluminum, was added to the autoclave from a catalyst tank installed above the autoclave. While maintaining the inner temperature at 50°C and the pressure at 0.2 MPa, polymerization was carried out for 6 hours. After the polymerization, the obtained polymer solution was gradually put into vigorously stirred excess methanol to precipitate the formed polymer, which was dried under reduced pressure at 60°C until no weight change was observed any longer, to obtain 1,000 g of the polymer. EXAMPLES 3 to 9 Polymerization and post treatment were carried out in the same manner as in Example 2 under the conditions shown in Table 1 by using, as a catalyst, the catalyst obtained in "Preparation A of transition metal compound as catalyst component", rac-dimethylmethylenebis(4,5-benz-1-indenyl)zirconium dichloride. However, in Example 7, methylalumoxane (PMAO, manufactured by TOSOH-AKZO K.K.) was used as a cocatalyst. Further, in Examples 4 and 5, ethylene was diluted with nitrogen gas to lower the ethylene partial pressure, whereby polymerization was carried out. EXAMPLES 10 and 11 Polymerization and post treatment were carried out in the same manner as in example 2 under the conditions shown in Table 1 by using, as a catalyst, the catalyst obtained in "Preparation B of transition metal catalyst component", rac-dimethylmethylene(1-indenyl)(4,5-benz-1-indenyl)zirconium dichloride. EXAMPLE 12 Polymerization and post treatment were carried out in the same manner as in Example 2 under the conditions shown in Table 1, except that the catalyst was changed to the complex mixture of rac-form and meso-form, obtained in "Preparation C of transition metal compound as catalyst component", which was weighed so that it contained 8.4 µmol of rac-dimethylmethylenebis(4,5-benz-1-indenyl)zirconiumbisdimethylamide, and used for polymerization. EXAMPLE 13 8.4 µmol of rac{BInd-C(Me) 2 -Ind}ZrCl 2 obtained in "Preparation B of transition metal compound as catalyst component" was dissolved in 20 ml of a toluene solution containing 1 mmol of triisobutylaluminum. Then, 20 ml of a toluene solution having 8.4 µmol of Ph 3 CB(C 6 F 5 ) 4 dissolved therein, was added thereto to obtain a catalyst solution. Into an autoclave having a capacity of 1 lit. and equipped with a stirrer, 400 ml of toluene and 80 ml of styrene were charged, and the catalyst solution was introduced under an ethylene pressure of 10 kg/cm 2 G) at an inner temperature of 17°C. Polymerization started immediately, and the inner temperature rised to the maximum of 74°C by heat generation. Polymerization was carried out for one hour while maintaining the pressure at a level of 1.1 MPa (10 kg/cm 2 G) during the polymerization. Post treatment was carried out in the same manner as in Example 2, to obtain 53 g of a polymer. EXAMPLE 14 Polymerization was carried out by using a polymerization reactor having a capacity of 150 lit. and equipped with a stirrer and a jacket for heating/cooling. 60 lit. of dry cyclohexane and 12 lit. of dry styrene were charged, and the inner temperature was raised to 33°C with stirring. Then, 84 mmol of triisobutylaluminum and 840 mmol, based on Al, of methylalumoxane (MMAO-3A, manufactured by TOSOH-AKZO K.K.) were added thereto. Ethylene was immediately introduced, and after the pressure was stabilized at 1.0 MPa (9 kg/cm 2 G), about 100 ml of a toluene solution containing 78 µmol of the catalyst obtained in "Preparation A of transition metal compound as catalyst component", rac-dimethylmethylenebis(4,5-benz-1-indenyl)zirconium dichloride, and 2 mmol of triisobutylaluminum, was added to the polymerization reactor from a catalyst tank installed above the polymerization tank. As heat generation started immediately, cooling water was introduced to the jacket. The inner temperature rose to the maximum of 80°C, but thereafter was maintained at about 70°C, and polymerization was carried out for 2.5 hours while maintaining the pressure at 1.0 MPa. After completion of the polymerization, the obtained polymerization solution was deaerated and then treated by a crumb forming method as follows to recover the polymer. The polymerization solution was put into 300 lit. of vigorously stirred water heated to 85°C containing a dispersant (Pluronic, tradename) over one hour. Then, it was stirred at 97°C for one hour, and then the hot water containing the crumb was put into cool water to recover the crumb. The crumb was dried in air at 50°C and then deaerated under vacuum at 60°C to obtain 12.8 kg of a polymer having a good crumb shape and having a size of about a few mm. COMPARATIVE EXAMPLE 1 With reference to J. Am. Chem. Soc., 110 , 6255 (1988) and J. Organomet. Chem, 459, 117 (1993), EWEN type Zr complex, diphenylmethylene (fluorenyl)(cyclopentadienyl)zirconium dichloride of the following formula, another name: {Flu-CPh 2 -Cp}ZrCl 2 , was prepared. Into an autoclave having a capacity of 120 ml and equipped with a stirrer, which was substituted by nitrogen and then by ethylene, 20 ml of styrene and 4.6 mmol of methylalumoxane (MMAO-3A, manufactured by TOSOH-AKZO K.K.) were charged and heated to 40°C. While maintaining the ethylene pressure at atmospheric pressure, 46 µmmol of the above {Flu-CPh 2 -Cp}ZrCl 2 dissolved in 20 ml of toluene, was added, and polymerization was carried out for one hour. During the polymerization, the temperature was maintained to be 40°C , and the presser was maintained to be atmospheric pressure (0 kg/cm 2 G). Post treatment after the polymerization was carried out in the same manner as in Example 1, to obtain 2.2 g of a white polymer. COMPARATIVE EXAMPLE 2 Polymerization and post treatment were carried out in the same manner as in Example 2 under the conditions shown in Table 1 by using the above diphenylmethylene (fluorenyl)(cyclopentadienyl)zirconium dichloride. From the amount of consumption of ethylene monitored, polymerization was found to be substantially completed in 4 hours. COMPARATIVE EXAMPLE 3 With reference to JP-A-7-053618, CGCT (constrained geometrical structure) type Ti complex, (tertiary butylamide)dimethyl(tetramethyl-η5-cyclopentadienyl)silanetitanium dichloride, another name: {CpMe 4 -SiMe 2 -NtBu}TiCl 2 , was prepared. Polymerization and post treatment were carried out in the same manner as in Example 2 under the conditions shown in Table 1 by using, as a complex, the CGCT (constrained geometrical structure) type Ti complex, (tertiary butylamide)dimethyl(tetramethyl-η5-cyclopentadienyl)silanetitanium dichloride. From the amount of consumption of ethylene monitored, polymerization was found to be substantially completed in 3 hours. COMPARATIVE EXAMPLES 4 and 5 Polymerization and post treatment were carried out in the same manner as in Example 2 under the conditions shown in Table 1 by using, as a complex, the CGCT (constrained geometrical structure) type Ti complex, (tertiary butylamide)dimethyl(tetramethyl-η5-cyclopentadienyl)silanetitanium dichloride. From the amount of consumption of ethylene monitored, in both Comparative Examples 4 and 5, polymerization was found to be substantially completed in 2.5 hours. COMPARATIVE EXAMPLE 6 With reference to Organometallics, 13 , 964 (1994), rac-dimethylsilylenebis(2-methyl-4,5-benzindenyl)zirconium dichloride, another name ras{2-Me-BInd-SiMe 2 -2-Me-BInd}ZrCl 2 , was prepared. Polymerization and post treatment were carried out in the same manner as in Example 2 under the conditions shown in Table 1 by using, as a complex, dimethylsilylenebis(2-methyl-4,5-benzindenyl)zirconium dichloride. From the amount of consumption of ethylene monitored, the polymerization was found to be substantially completed in 2 hours. COMPARATIVE EXAMPLE 7 With reference to Angew. Chem. Int. Ed. Engl. 24 , 507 (1985), rac-ethylenebis(1-indenyl)zirconium dichloride, another name: rac{Ind-Et-Ind}ZrCl 2 , was prepared. Polymerization and post treatment were carried out in the same manner as in Example 2 under the conditions shown in Table 1 by using, as a complex, rac-ethylenebis(1-indenyl)zirconium dichloride. From the amount of consumption of ethylene monitored, polymerization was found to be substantially completed in 6 hours. Table 1 shows the copolymerization results. Figure 1 shows the productivity of a polymer per catalyst in each Example or Comparative Example wherein polymerization was carried out by using a 10 lit. autoclave. It is evident that the catalysts in Examples exhibit remarkably high productivity as compared with the catalysts of Comparative Examples. Table 2 shows the styrene content, the molecular weight obtained by GPC, and the glass transition point and the melting point obtained by DSC, of the obtained polymer. Figures 2 and 3 show a GPC chart and a DSC chart of the copolymer obtained in Example 2 as a typical example of the styrene-ethylene copolymer of the present invention. In the GPC measurements of polymers obtained in various Examples except for Example 1 wherein the polymerization scale was very small, the GPC curves obtained by different detectors (RI and UV) agreed within an experimental error range, as shown in Figure 2. This indicates that each copolymer has an extremely uniform compositional distribution. Further, the glass transition point obtained by DSC in Table 2, was one. This also indicates a uniform composition of the copolymer. 1H-NMR spectra of the polymers obtained in Examples 3 and 4 are shown in Figures 4 and 5. The styrene-ethylene random copolymer of the present invention is specifically a copolymer containing a typical structure represented by the following formula in an optional proportion. In the methine and methylene carbon regions in the 13C-NMR spectra, peaks attributable to the following, are shown. Symbols a to o are symbols representing carbon atoms shown in the chemical structures of the formulas (2) and K-32 to K-40. Peaks attributable to the following, are shown using the center peak (73.89 ppm) of the triplet of 1,1,2,2-tetrachloroethane-d2 as standard. (1) Alternating structure of styrene and ethylene wherein Ph is a phenyl group, and x is an integer of at least 2, representing the number of repeating units. Namely, it represents a structure of the following formula which comprises methine carbon atoms bonded to the Ph groups and three methine carbon atoms sandwiched therebetween. For simplicity, hydrogen atoms are omitted. (2) Chain structure of ethylene (3) Structure comprising an ethylene chain and one unit of styrene (4) Structure comprising inversion (tail-to-tail structure) of styrene units (5) Structure comprising ethylene units or an ethylene chain, and a head-to-tail chain of two styrene units Or, a structure wherein styrene units and styrene-ethylene alternating structural units are randomly bonded. Styrene unit: Alternating structural unit: (6) Structure comprising a head-to-tail chain of at least three styrene units 25.1-25.2 ppm (c) 36.4-36.5 ppm (b) 44.8-45.4 ppm (a) 29.4-29.9 ppm (g) 36.5-36.8 ppm (e) 27.2-27.6 ppm (f) 45.4-46.1 ppm (d,h) 34.5-34.9 ppm (I) 42.4-43.0 ppm (j) 43.7-44.5 ppm (k) 35.6-36.1 ppm (l) 24.0-24.9 ppm (m) 40.7-41.0 ppm (n) 43.0-43.6 ppm (o) The above peaks may have some shifts, micro structures of peaks or peak shoulders, due to an influence of the measuring conditions, the solvent used, etc. or due to a distanced effect from the adjacent structure. Attribution of these peaks was made by literatures such as Macromolecules, 13 , 849 (1980), Stuf. Surf. Sci. Catal., 517, 1990, J. Appln. Polymer Sci., 53 , 1453 (1994), J. Polymer PHys. Ed., 13 , 901 (1975), Macromolecules, 10 , 773 (1977), Polymer Preprints, Japan, 42 , 2292 (1993), EP-416815 and JP-A-4-130114, and by the peak shift prediction by the 13C-NMR Inadequate method, the DEPT method, and the 13C-NMR data base STN (Specinfo). As typical examples, the 13C-NMR charts of Examples 3, 4, 6, 9, 10, 12 and 13 and Comparative Examples 1 and 3, are shown in Figures 6 to 23. The 13C-NMR peak positions of copolymers obtained by typical Examples and Comparative Examples, are shown in Table 3. The enlarged 13C-NMR spectra of Examples and Comparative Examples are shown in Figures 24 and 25. However, only in the spectrum of Comparative Example 1, CDCl 3 is used as the solvent, and for the purpose of comparing with other spectra (1,1,2,2-tetrachloroethane-d2), the peak positions are shown as corrected. The alternating structural index λ, the isotactic diad index m of the styrene-ethylene alternating structure and the isotactic diad index ms of the head-to-tail styrene chain unit structure, of the copolymer obtained in each Example, were obtained in accordance with the above formulas (i), (ii) and (iii). The m and ms values obtained in the respective Examples and Comparative Examples are shown in Table 4. Examples St content (mol%) Value λ Value m Value ms Ex.1 41. 0 48 >0. 95 >0. 80 Ex.2 53. 8 60 >0. 9 5 >0. 8 0 Ex.3 55. 5 57 >0. 9 5 > 0. 8 0 Ex.4 72. 9 20 >0. 95 >0. 80 Ex.5 92. 0 7 >0. 95 >0. 80 Ex.6 15. 5 8 >0. 95 - Ex.7 11. 5 6 >0. 95 - Ex.8 7. 0 4 >0. 95 - Ex.9 37. 1 47 >0. 95 - Ex.10 47. 1 59 >0. 95 >0. 80 Ex.11 31. 8 25 >0. 95 - Ex.12 33. 9 30 >0. 95 - Ex.13 2 5. 8 1 9 >0. 95 - Ex.14 27. 9 18 >0. 95 - Comp. Ex.1 43. 0 NM 0. 6 5 - Comp. Ex.2 21. 1 NM 0. 7 - Comp. Ex.3 49. 8 NM 0. 60 - Comp. Ex.4 13. 0 NM 0. 5 - Comp. Ex.5 9. 0 NM 0. 5 - Comp. Ex.6 <2 NM NM - Comp. Ex.7 9.5 NM 0. 9 - NM: Not measured Note: -: No distinct peak attributable to a at least three head-to-tail styrene chain (a polystyrene chain), was observed by the 13-CNMR measurement commonly carried out in Examples (accumulated number of times: about 5,000 times), and no calculation was accordingly possible. Further, the isotactic pentad index mmmm of styrene units, can be obtained by the following formula from the peak of the phenyl C1 carbon or the methylene carbon of the styrene chain structure by the 13C-NMR measurement. mmmm = A(mmmm)/A(all) A(mmmm): peak area of phenyl C1 carbon attributable to the mmmm structure of the styrene chain A(all): Sum of all peak areas of phenyl C1 carbon attributable to the stereoregularity. Especially, in the case of the phenyl C1 carbon peak, a peak attributable to phenyl C1 of the copolymer structure is present in the vicinity of the mmmm peak of a head-to-tail styrene chain, but no substantial peak is observed in the vicinity of from 145.2 to 146.0 ppm which is the position where the peak attributable to an atarctic styrene chain or a syndiotactic styrene chain structure appears. Thus, mmmm is at least 0.2. To show that the copolymer of the present invention can have a crystalline structure, the X-ray diffraction patterns of the copolymers obtained in Examples 10 and 14 are shown in Figure 26. The samples were subjected to suitable annealing treatment to improve the crystallinity, whereupon the measurements were carried out. With a styrene-ethylene random copolymer of the present invention with a styrene content of at least 15 mol%, a diffraction peak from the crystal structure attributable to the stereoregular styrene-ethylene alternating structure contained, was observed. When the styrene content is less than about 15 mol%, a diffraction peak from a crystal structure of polyethylene will also be observed. When a CGCT (constrained geometrical structure) type Ti complex, (tertiary butylamide)dimethyl(tetramethyl-η5-cyclopetandienylsilanetitanium dichloride or diphenylmethylene(fluorenyl)(cyclopentadienyl)zirconium dichloride, is employed as the transition metal catalyst component, the styrene-ethylene alternating structure in the resulting copolymer, has no stereoregularity. Further, no head-to-tail styrene chain is observed. When rac-ethylenebis(1-indenyl)zirconium dichloride is used as the transition metal catalyst component, it is very difficult to increase the styrene content to a level of at least 10 mol%, and the molecular weight of the resulting polymer is as low as 50,000 by weight average molecular weight (Mw). The copolymer with a styrene content of at least 5 mol% and less than 20 mol%, which has a weight average molecular weight of less than 60,000, is not useful as a practical polymer, since the physical properties such as breaking strength, etc. are poor. When the same transition metal catalyst component is employed, as shown in Comparative Example 10, homopolymerization of styrene does not proceed. It is impossible to form a styrene chain by this catalyst system. When dimethylsilylenebis(2-methyl-4,5-benzindenyl)zirconium dichloride having a substituent pattern of the benzindenyl group which is different from the transition metal compound as catalyst component for polymerization of the present invention, is employed, a copolymer having a styrene content of not more.than 2 mol%, is obtained. Namely, when a metal complex having a substituent at the 2-position of the benzindenyl group, is used, it is impossible to obtain a high styrene content. Further, no head-to-tail styrene chain is observed. When the same transition metal catalyst component is used, as shown in Comparative Example 9, no styrene polymer having stereoregularity can be obtained. An atarctic polystyrene produced in a small amount, is considered to have been formed by cation or radical polymerization, according to known literatures. Thus, it is impossible to form a styrene chain by this catalyst system. Preparation of styrene-propylene random copolymers EXAMPLE 15 An autoclave having a capacity of 1 lit. and equipped with a stirrer, was evacuated and substituted by nitrogen, and then 100 ml of styrene, 40 ml of toluene, 5 mmol of triisobutylaluminum and 21 mmol, based on Al atom, of methylalumoxane (MMAO-3A, manufactured by TOSOH-AKZO K.K.) were charged in this order. Then, the autoclave was cooled to -50°C by dry ice, and 1 mol of propylene gas was introduced. About 40 ml of a toluene solution containing 21 µmol of a catalyst rac{BInd-C(Me) 2 -BInd}ZrCl 2 and 0.84 mmol of triisobutylaluminum, was introduced together with propylene gas, from a pressure resistant tank installed above the autoclave. The dry ice bath was removed, and temperature was raised to 50°C over a period of about 30 minutes and polymerization was carried out at 50°C for one hour. After completion, the pressure was gradually released, and the polymerization solution was post-treated in the same manner as in Example 1 to obtain 8.5 g of a polymer. EXAMPLES 16 to 18 Polymerization and post treatment were carried out in the same manner as in Example 15 under the polymerization conditions shown in Table 5. COMPARATIVE EXAMPLE 8 Polymerization and post treatment were carried out in the same manner as in Example 15 under the conditions shown in Table 2, using, as a complex, dimethylsilylenebis(2-methyl-4,5-benzindenyl)zirconium dichloride. Table 5 shows the polymerization conditions and the results. Table 6 shows the styrene content and the molecular weight obtained by GPC, of the obtained polymer, and the results of the glass transition point and melting point obtained by DSC. Figures 27 and 28 show the GPC chart and the DSC spectrum of the copolymer obtained in Example 15. In the GPC measurements of the polymers obtained in various Examples, the GPC curves obtained by different detectors (RI and UV) agree to each other within an experimental error range, as shown in Figure 27, although a small shoulder is observed. This indicates that the compositional distribution of styrene is relatively uniform. The glass transition point obtained by DSC being one, also indicates a uniform composition of the copolymer. Typical 13C-NMR charts of Examples 15, 17 and 18 are shown in Figures 29 to 34. Table 7 shows the results of 13C-NMR measurements. The styrene-propylene copolymers of the present invention present complex peak patterns by the 13C-NMR measurements, as shown in the Figures. This indicates that many different kinds of bond structures were formed, for example, by formation of head-to-tail or tail-to-tail chains of propylene units one another, styrene units one another or a propylene unit and a styrene unit bonded to each other, or a structure similar to an ethylene chain due to a 1-3 bond of propylene. However, among peaks of phenyl C1 carbon of a styrene unit (the carbon bonded to the main chain among six carbon atoms of a phenyl group), the peak in the vicinity of 146.3 ppm is attributable to an isotactic polystyrene chain, and the peak at 21.5 to 21.6 ppm of methyl carbon in a propylene unit, is attributable to an isotactic polypropylene chain. Namely, it is a copolymer which has a styrene chain structure, a propylene chain structure and a styrene-propylene bond structure, wherein the stereoregularity of the styrene chain structure and/or the propylene chain structure is isotactic. In the case of a propylene chain, the isotactic index (mm, mmm or mmmm) is obtained by comparing the area of an isotactic peak (mm, mmm or mmmm) of a methyl group in the vicinity of 21.5 ppm and the area of peaks of all methyl groups. With respect to the propylene chain, the isotactic index (mm, mmm or mmmm) is such that mm is at least 0.5, mmm is at least 0.4, and mmmm is at least 0.2, although other peaks attributable to the above-mentioned complex bond structures, are present in the vicinity. In the case of a styrene chain, the isotactic index (mm, mmm or mmmm) can be obtained by comparing the area of the isotactic peak (mm, mmm or mmmm) of the phenyl C1 group in the vicinity of 146.3 ppm and the area of all phenyl C1 peaks in the vicinity of from 145 to146 ppm. With respect to the styrene chain, the isotactic index (mm, mmm or mmmm) is such that mm is at least 0.5, mmm is at least 0.4, and mmmm is at least 0.2. When dimethylsilylenebis(2-methyl-4,5-bnzoindenyl)zirconium dichloride having a substituent pattern on a benzindenyl group which is different from the transition metal catalyst component for polymerization of the present invention, is used, a mixture comprising an isotactic polypropylene and an atarctic polystyrene, will be obtained. Preparation of isotactic polystyrenes Into a Shrenk tube having a capacity of 100 ml and equipped with a magnetic stirrer, which was evacuated and substituted by nitrogen, 10 ml of styrene and 0.84 mmol of triisobutylaluminum were charged. Further, 0.8 µmol, based on Al, of methyl alumoxane (MMAO-3A, manufactured by TOSOH-AKZO K.K.) was added thereto, and 10 ml of a toluene solution containing 1.5 µmol of rac-dimethylmethylenebis(4,5-benz-1-indenyl)zirconium dichloride, was added thereto. The mixture was stirred at room temperature for 3 hours and then put into a large excess amount of methanol acidified with hydrochloric acid to precipitate a polymer. The obtained polymer was dried at 70°C for 8 hours to obtain 1.5 g of a white powdery polymer. EXAMPLE 20 Polymerization and post treatment were carried out in the same manner as in Example 19 under the conditions shown in Table 3 by using, as a complex, 4.6 µmol of rac-dimethylmethylene(4,5-benz-1-indenyl)(1-indenyl)zirconium dichloride, to obtain 0.5 g of a white powdery polymer. COMPARATIVE EXAMPLE 9 Polymerization and post treatment were carried out in the same manner as in Example 13 under the conditions shown in Table 3, by changing the complex to rac-dimethylsilylbis(2-methyl-4,5-benzindenyl)zirconium dichloride, another name: rac{2-Me-BInd-SiMe 2 -2-Me-BInd}ZrCl 2 , to obtain 0.15 g of a white powdery polymer. COMPARATIVE EXAMPLE 10 Polymerization and post treatment were carried out in the same manner as in Example 19 under the conditions shown in Table 3 by changing the complex to rac-ethylenebis(1-indenyl)zirconium dichloride, another name: rac{Ind-Et-Ind}ZrCl 2 , whereby no polymer was obtained. Table 8 shows the polymerization conditions and the results. Table 9 shows the molecular weight of the obtained polymer determined by GPC, and the results of the glass transition point and melting point determined by DSC. The 13C-NMR chart of the obtained polymer is shown in Figure 35, the DSC chart is shown in Figure 36, and the X-ray diffraction pattern is shown in Figure 37. The peak shift value of the 13C-NMR obtained by using the center peak (73.89 ppm) of the triplet of 1,1,2,2-tetrachloroethane-d2, as standard, was as follows. Methine carbon Methylene carbon Phenyl C1 carbon EXAMPLE 19 40.7 43.0 146.3 EXAMPLE 20 40.7 43.0 146.3 The melting point obtained by DSC was 222°C, and from the results of the X-ray diffraction, it is evident that the obtained copolymer was an isotactic polystyrene. The meso pentad index (mmmm) obtained from the peak of the phenyl C1 carbon of the isotactic polystyrene obtained in Example 19, was at least 0.90. In the case of Comparative Example 9 wherein rac-dimethylsilylenebis(2-methyl-4,5-benzindenyl)zirconium dichloride was used, a very small amount of atarctic polystyrene was obtained, but this is considered to have been formed by radical polymerization or cation polymerization by the coexisting methylalumoxane or an alkylaluminum included therein. In the case of Comparative Example 10 wherein rac-ethylenebis(1-indenyl)zirconium dichloride was used, no polymer was obtained. Preparation of styrene-ethylene alternating copolymers EXAMPLE 21 Polymerization was carried out by using an autoclave having a capacity of 1 lit. and equipped with a stirrer. 240 ml of toluene and 240 ml of styrene were charged, and the inner temperature was raised to 50°C. About 80 lit of nitrogen was introduced for bubbling to purge the interior of the system. Then, the autoclave was cooled by immersing it in an ice bath. Then, 8.4 mmol of triisobutylaluminum and 8.4 mmol, based on Al, of methylalumoxane (PMAO-S, manufactured by TOSOH-AKZO K.K.) were added thereto. Ethylene was immediately introduced, and after the pressure was stabilized at 0.2 MPa (1 kg/cm 2 G), about 30 ml of a toluene solution containing 6 µmol of a catalyst obtained in "Preparation A", rac-dimethylmethylene bis(4,5-benz-1-indenyl)zirconium dichloride and 0.84 mmol of triisobutylaluminum, was added to the autoclave from a catalyst tank installed above the autoclave. Polymerization was carried out for 6 hours while maintaining the inner temperature at a level of 2 to 6°C and the ethylene pressure at a level of 0.2 MPa(1 kg/cm 2 G). During the polymerization, the rate of consumption of ethylene was monitored by a flow rate accumulator, so that the progress of the polymerization reaction was monitored. Upon expiration of 6 hours, polymerization was substantially in progress without no deactivation. The ethylene pressure was released, and the obtained polymerization solution was gradually put into an excess amount of methanol to precipitate the formed polymer. The product was dried for about 10 hours under reduced pressure at 80°C until no weight change was any longer observed, to obtain 39 g of a polymer. EXAMPLE 22 Polymerization and post treatment was carried out in the same manner as in Example 21 except that the complex was used in an amount of 8.4 µmol, and polymerization was carried out by immersing the autoclave in a cooling bath of -20°C to maintain the inner temperature at -16°C, to obtain 1.5 g of a polymer. This polymer contained atarctic polystyrene homopolymer, and it was further subjected to extraction treatment with boiling acetone, whereby 0.7 g of a white powder polymer was obtained as an insoluble fraction in boiling acetone. COPARATIVE EXAMPLE 11 Polymerization and post treatment were carried out in the same manner as in Example 21 under the conditions shown in Table 4, by using, as the catalyst, ethylenebisindenylzirconium dichloride. As a result, 14 g of a polymer was obtained. The obtained copolymer was a mixture of atarctic polystyrene and the copolymer, and it was extracted with boiling acetone to obtain 8 g of a white polymer as an insoluble fraction in boiling acetone. The polymerization conditions and the polymerization results in the respective Examples and Comparative Examples are shown in Table 10. Further, the molecular weights, the molecular weight distributions, the melting points and the glass transition temperatures of the copolymers obtained in the respective Examples and Comparative Examples are shown in Table 11, and the 13C-NMR peak shift values are shown in Table 12. As an example of the copolymer obtainable by the present invention, the 1H-NMR of the copolymer obtained in Example 21 is shown in Figure 38, and the 13C-NMR spectrum is shown in Figures 39 and 40. The aromatic vinyl compound-ethylene alternating copolymer obtained by the present invention, is an aromatic vinyl compound-ethylene alternating copolymer characterized in that the stereoregularity of phenyl groups in the alternating structure of ethylene and the aromatic vinyl compound, is represented by an isotactic diad index m of larger than 0.95, and the alternating structure index λ of the following formula (i) is at least 70. The alternating index λ is given by the following formula (i): λ = A3/A2×100 Here, A3 is the sum of areas of three peaks a, b and c attributable to the carbons of aromatic vinyl compound-ethylene alternating structure of the following formula (5'), as obtained by the 13C-NMR measurements, and A2 is the sum of areas of peaks attributable to the main chain methylene and methine carbon, as observed within a range of from 0 to 50 ppm by 13C-NMR using TMS as standard. wherein Ph is an aromatic group such as a phenyl group, and x is an integer of at least 2, representing the number of repeating units, wherein Ph is an aromatic group such as a phenyl group, and x is an integer of at least 2, representing the number of repeating units. Namely, it has a structure represented by the following formula which comprises methine carbon atoms bonded to the Ph groups and three methylene carbon atoms sandwiched therebetween. (For the simplicity, hydrogen atoms are omitted.) The isotactic diad (meso diad) index m of the alternating copolymer structure of ethylene and styrene, can be obtained by the above formula (ii). Further, the alternating structure index λ obtained by the above formula is shown in Table 13. The isotactic diad index m of the styrene unit-ethylene unit alternating structure of the copolymer obtained in each Example, was obtained by the above formula. Table 13 shows m obtained in each Example or Comparative Example. As an example of the copolymer obtainable by the present invention, the GPC chart of the copolymer obtained in Example 21 is shown in Figure 41. As an example of the copolymer obtainable by the present invention, the DSC chart of the copolymer obtained in Example 22 (measured after quenching with liquid nitrogen from a molten state, the temperature raising rate: 20°C/min) is shown in Figure 42. It is evident from Figure 42 that the copolymer of the present invention has a high melting point and a high crystallization speed. As an example of the copolymer obtainable by the present invention, the X-ray diffraction chart of the copolymer obtained in Example 21 is shown in Figure 43. As shown in Comparative Example 11, in a case where ethylenebisindenylzirconium dichloride is used as a metal complex, the styrene content can not be increased under a practical polymerization temperature condition of at least -20°C, whereby it is impossible to obtain a copolymer having a high alternating nature. TEST EXAMPLES Preparation D of transition metal compound as catalyst component Rac-dimethylmethylenebis(3-cyclopenta[c]phenanthryl)zirconium dichloride (rac{CpPhen-CMe 2 -CpPhen}ZrCl 2 ), was prepared as follows. Here, CpPhen represents cyclopentadienyl[c]phenanthryl. 1H or 3H-cyclopenta[c]phenanthrene was prepared in accordance with the method disclosed in Organometallics, 16, 3413, 1997. D-1 Isopropylidenebis(cyclopenta[c]phenanthrene) In an Ar atmosphere, 32 mmol of 1H or 3H-cyclopenta[c]phenanthrene was added to 40 ml of dimethoxyethane having 3.0 g of potassium hydroxide suspended therein, and the mixture was stirred at room temperature for 30 minutes. Then, 15 mmol of acetone was added thereto, followed by stirring at 60°C for 2 hours. A 10% phosphoric acid aqueous solution was added for neutralization, and the mixture was extracted with methylene chloride. The organic layer was washed with water and dried, and methylene chloride was distilled off. By recrystallization from a methylene chloride-diethyl ether solution, 1.5 g of isopropylidenebis(cyclopenta[c]phenanthrene) was obtained as white crystals. By the 1H-NMR spectrum measurement, it had peaks at 1.93 ppm (6H,s), 4.20 ppm (4H,d), 6.89 ppm (2H,t), 7.5 to 7.9 ppm (14H,m) and 8.91 ppm (2H,d). The measurement was carried out by using TMS as standard and CDCl 3 as the solvent. D-3 Preparation of rac-dimethylmethylenebis(3-cyclopenta[c]phenanthryl)zirconium dichloride In an Ar stream, 2.0 mmol of isopropylidenebis(cyclopenta[c]phenanthrene) and 2.0 mmol of zirconium tetrakisdimethylamide{Zr(NMe 2 ) 4 } were charged together with 20 ml of toluene and stirred for 7 hours under reflux. Toluene was distilled off under reduced pressure, and 50 ml of methylene chloride was added thereto. The mixture was cooled to -50°C. Then, 4.0 mmol of dimethylamine hydrochloride was gradually added, and the temperature was slowly raised to room temperature, and stirring was further conducted for 2 hours. After distilling off the solvent, the obtained solid was washed with pentane and then with a small amount of methylene chloride to remove meso-isomer and ligand, to obtain 0.36 g of rac-dimethylmethylenebis(3-cyclopenta[c]phenanthryl)zirconium dichloride as yellow orange crystals. From the 1H-NMR spectrum, it was found to have peaks at 2.55 ppm (6H,s), 6.49 ppm (2H,d), 7.55-8.02 ppm (16H,m), and 8.82 ppm (2H,d). The measurement was carried out by using TMS as standard and CDCl 3 as a solvent. Preparation of styrene-ethylene random copolymers EXAMPLE 23 Polymerization and post treatment were carried out in the same manner as in Example 2 under the conditions shown in Table 14, by using, as a catalyst rac-dimethylmethylenebis(3-cyclopenta[c]phenanthryl)zirconium dichloride which is the catalyst obtained in "Preparation D of transition metal compound as catalyst component". As a result, 910 g of a polymer was obtained. The styrene content was 57.0 mol%, the molecular weight (Mw) was 279,000, the molecular weight distribution (Mw/Mn) was 2.0, and the glass transition point was 40°C. As a result of the 13C-NMR measurement, a peak was observed which is attributable to two or more head-to-tail styrene chain structure. The 13C-NMR spectra are shown in Figures 44, 45 and 46. The peak shift values of the 13C-NMR spectra are shown in Table 15. The stereoregularity of the styrene-ethylene alternating structure was isotactic, and m was at least 0.95, ms was at least 0.80, and the alternating structure index λ was 30. When this complex is used as a catalyst component, it is possible to obtain a copolymer having a high random nature (low alternating nature) under the conditions of Examples. EXAMPLE 24 Polymerization and post treatment were carried out in the same manner as in Example 19 under the conditions shown in Table 14, by using, as a catalyst, rac-dimethylmethylenebis(3-cyclopenta[c]phenanthryl)zirconium dichloride which is the catalyst obtained in "Preparation D of transition metal compound as catalyst component". As a result, 1.8 g of a polymer was obtained. The molecular weight (Mw) was 208,000, the molecular weight distribution (Mw/Mn) was 1.7, and the melting point was 225°C. The peak shift values of 13C-NMR obtained by using the center peak (73.89 ppm) of the triplet of 1,1,2,2-tetrachloroethane-d2 as standard, were as follows. Methine carbon Methylene carbon Phenyl C1 carbon EXAMPLE 24 40.7 43.0 146.3 The meso pentad index (mmmm) obtained from the phenyl C1 carbon peak was at least 0.95. When rac-dimethylmethylenebis(3-cyclopenta[c]phenanthryl) zirconium dichloride is used as a transition metal catalyst component, it is possible to produce a styrene-ethylene random copolymer having a high molecular weight and an isotactic polystyrene under very high catalytic activities. REFERENCE EXAMPLE 1 Preparation of polyethylene Into an autoclave having a capacity of 120 ml and equipped with a magnetic stirrer, which was evacuated and substituted by ethylene, 20 ml of toluene and 8.4 µmol, based on Al atom, of methylalumoxane (MMAO-3A, manufactured by TOSOH AKZO K.K.) were charged. The inner temperature was raised to 50°C, and 16 ml of a toluene solution containing 1.0 µmol of rac{BInd-C(Me) 2 -BInd}ZrCl 2 and 0.84 mmol of triisobutylaluminum, was quickly charged by a syringe with magnetic stirring, and ethylene was immediately introduced to raise the pressure to a total pressure of 0.6 MPa (5 kg/cm 2 G). Polymerization was carried out for 10 minutes while maintaining the pressure at a level of 5 kg/cm 2 G. The polymerization solution was put into a large excess amount of dilute hydrochloric acid/methanol liquid to precipitate a polymer, which was dried under vacuum at 70 °C for 8 hours. As a result, 1.7 g of a polyethylene was obtained. As a result of the DSC measurement, the melting point was 130°C. Examples St content (mol%) Mw /10 4 Mn /10 4 Mw/Mn Glass transition temp. (°C) Melting point (°C) Ex.15 55. 6 2. 0 1. 2 1. 7 35 Ex.16 4 2. 2 1. 6 0. 9 1. 8 35 Ex.17 3. 9 1. 7 1. 0 1. 0 - 1 8 1 18 Ex.18 7 2. 5 1 . 6 0. 9 1 . 7 75 Comp. Ex.8 100 2. 1 0. 7 3 . 0 - - ∼0 11. 2 4 . 6 2 . 5 - - Examples Mw /10 4 Mn /10 4 Mw/Mn Glass transition temp. (°C) Melting point point (°C) Ex. 19 3. 6 1. 9 1. 9 85 2 2 2 Ex. 20 2 . 0 1 . 1 1 . 9 85 2 2 0 Comp. Ex.9 1. 0 0. 6 1. 7 88 Comp. Ex.10 - - - - - Examples St content (mol%) Mw /10 4 Mn /10 4 Mw/Mn Glass transition temp. (°C) Melting point (°C) Ex.21 53. 3 31. 7 23. 7 1. 3 27 134 Ex.22 50. 0 2. 0 1 . 1 1. 8 2 2 153 Comp. Ex.11 27. 0 2. 4 1. 3 1. 8 -2 1 20 Examples Value λ Value m Ex.21 78 1. 0 Ex.22 8 0 1 . 0 Comp. Ex.11 35 0. 90 Main peak shift values (ppm) by 13C-NMR, obtained by using 1,1,2,2-tetrachloroethane d2 as a solvent Attribution Ex.23 cm 25.12 r - a mm 45.18-45.27 mr - rr - b m(m) 36.46 m(r) - r(m) - r(r) - g 29.3-29.7 n mmmm 40.8-40.9 rrrr - o mmmm 43.3-43.6 rrrr j 42.8-42.9 k 43.9-44.1 Note: -: No distinct peak was observed by the 13-CNMR measurement commonly conducted in Examples (accumulated number of times: about 5,000 times). Using 1,1,2,2-tetrachloroethane-d2 as a solvent, the sample was heated and dissolved at 100°C and then subjected to the measurement. The center peak of the triplet of tetrachloroethane by 13C- NMR had a shift value of 73.89 ppm relative to TMS. Each peak shift value of a copolymer was calculated relative to the center peak value of the triplet of tetrachloroethane being 73.89 ppm.

Claims: A transition metal compound of the following formula (1) as catalyst component for the production of an aromatic vinyl compound polymer or an aromatic vinyl compound-olefin copolymer: wherein A is an unsubstituted or substituted benzindenyl group of the following formula K-2, K-3 or K4: wherein each of R1 to R3 is hydrogen, a C 1-20 alkyl group, a C 6-10 aryl group, a C 7-20 alkylaryl group, a halogen atom, OSiR 3 , SiR 3 or PR 2 (wherein each R is a C 1-10 hydrocarbon group), provided that the plurality of R1, the plurality of R2 and the plurality of R3 may be the same or different, respectively, and each pair of adjacent R1, adjacent R2 and adjacent R3 may together, with the atoms joining them, form a 5- to 8- member aromatic or aliphatic ring, B is an unsubstituted or substituted benzindenyl group of the same chemical formula as A, or an unsubstituted or substituted cyclopentadienyl group, an unsubstituted or substituted indenyl group or an unsubstituted or substituted fluorenyl group, of the formula K-5, K-6 or K-7: wherein each of R4 to R6 is hydrogen, a C 1-20 alkyl group, a C 6-10 aryl group, a C 7-20 alkylaryl group, a halogen atom, OSiR 3 , SiR 3 or PR 2 (wherein each R is a C 1-10 hydrocarbon group), provided that the plurality of R4, the plurality of R5 and the plurality of R6 may be the same or different, respectively, when both A and B are unsubstituted or substituted benzindenyl groups, they may be the same or different, Y is a methylene group or a silylene group, which has bonds to A and B and which has, as substituents, hydrogen or a C 1-15 hydrocarbon group, wherein the substituents may be the same or different from each other, or Y may have, together with the substituents, a cyclic structure, X is hydrogen, a halogen atom, an alkyl group, an aryl group, an alkylaryl group, a silyl group, a methoxy group, an ethoxy group, an alkoxy group or a dialkylamide group, and M is zirconium, hafnium or titanium. The transition metal compound as catalyst component according to claim 1, wherein A is a 4,5-benz-1-indenyl group, a 5,6-benz-1-indenyl group, a 6,7-benz-1-indenyl group, an α-acenaphtho-1-indenyl group, a 3-cyclopenta[c]phenanthryl group or a 1-cyclopenta[1]phenanthryl group, and B is a 4,5-benz-1-indenyl group, a 5,6-benz-1-indenyl group, a 6,7-benz-1-indenyl group, an α-acenaphtho-1-indenyl group, a 3-cyclopenta[c]phenanthryl group, a 1-cyclopenta[1]phenanthryl group, a 1-indenyl group, 4-phenyl 1-indenyl group or a 4-naphthyl 1-indenyl group; and/or wherein M is zirconium, and Y is a methylene group which has, as substituents, hydrogen or a C 1-15 hydrocarbon group; and/or wherein X is a dialkylamide. The transition metal compound as catalyst component according to claim 1, wherein A is a 3-cyclopenta[c]phenanthryl group, and B is a 3-cyclopenta[c]phenanthryl group, an unsubstituted or substituted benz-1-indenyl group of the formula K-2, K-3 or K-4, or an unsubstituted or substituted 1-indenyl group of the formula K-6, M is zirconium, hafnium or titanium, and Y is a methylene group or a silylene group, which has bonds to A and B and which has, as substituents, hydrogen or a C 1-15 hydrocarbon group, wherein the substituents may be the same or different from each other, or Y may have, together with the substituents, a cyclic structure. The transition metal compound according to claim 1, wherein X is hydrogen, a halogen, a C 1-15 alkyl group, a C 6-10 aryl group, a C 8-12 alkylaryl group, a silyl group having a C 1-4 hydrocarbon substituent, a C 1-10 alkoxy group, or a dialkylamide group having a C 1-6 alkyl substituent. A transition metal compound as catalyst component of the following formula (2-1) or (2-2) for the production of an aromatic vinyl compound polymer or an aromatic vinyl compound-olefin copolymer: wherein A, B, Y, M and X are as defined with respect to the formula (1 ) in claim 1, wherein the angle (the bite angle) between metal M and the centroid of each cyclopentadienyl structure in A and B, is at most 120°. A polymerization catalyst for the production of an aromatic vinyl compound polymer or an aromatic vinyl compound-olefin polymer, which comprises a transition metal compound as catalyst component as defined in Claim 1 or 5 and a cocatalyst. The polymerization catalyst for the production of an aromatic vinyl compound polymer or an aromatic vinyl compound-olefin copolymer according to Claim 6, wherein as the cocatalyst, a boron compound or an aluminoxane (or an alumoxane) of the following formula (3) or (4) is used, and if necessary, an alkylaluminum is used: wherein R is a C 1-5 alkyl group, a C 6-10 aryl group or hydrogen, and m is an integer of from 2 to 100, provided that the plurality of R may be the same or different, wherein R' is a C 1-5 alkyl group, a C 6-10 aryl group or hydrogen, and n is an integer of from 2 to 100, provided that the plurality of R' may be the same or different. A method for producing an aromatic vinyl compound polymer or an aromatic vinyl compound-olefin copolymer, preferably an isotactic aromatic vinyl compound polymer or an aromatic vinyl compound-olefin copolymer having an isotactic structure, wherein polymerization is carried out by means of a polymerization catalyst comprising a transition metal compound as defined in claim 1 or 5 and a cocatalyst. An aromatic vinyl compound-olefin copolymer, preferably an aromatic vinyl compound-ethylene copolymer or an aromatic vinyl compound-propylene copolymer, obtained by polymerization by means of a pelymerization catalyst comprising a transition metal compound as defined in claim 1 or 5 and a cocatalyst. The aromatic vinyl compound-olefin copolymer according to claim 9, wherein the aromatic vinyl compound is styrene. An aromatic vinyl compound-ethylene random copolymer having an isotactic structure, which has an aromtaic vinyl compound content of from 5 to 99.9 mol% and which has a head-to-tail chain structure of at least two aromatic vinyl compound units. An aromatic vinyl compound-ethylene random copolymer having an aromatic vinyl compound content of from 5 to 99.9 mol% and having a head-to-tail structure of at least 2 aromatic vinyl compound units attributable to a peak observed at from 40 to 45 ppm by the 13C-NMR measurement using TMS as standard. The aromatic vinyl compound-ethylene random copolymer according to claim 11 or 12, wherein the aromatic vinyl compound is styrene. The aromatic vinyl compound-ethylene random copolymer according to any one of claims 11 to 13, wherein the stereoregularity of phenyl groups in an alternating structure of an aromatic vinyl compound and ethylene of the following formula (5) is represented by an isotactic diad index m of larger than 0.75, and the alternating structure index λ of the following formula (i) is smaller than 70 and larger than 1: λ = A3/A2 x 100 where A3 is the sum of areas of three peaks a, b, and c attributable to the carbons of an aromatic vinyl compound-ethylene alternating structure of the following formula (5'), as obtained by the 13C-NMR measurement, and A2 is the sum of areas of peaks attributable to the main chain methylene and the main chain methine carbon, as observed within a range of from 0 to 50 ppm by 13C-NMR using TMS as standard, wherein Ph is an aromatic group such as a phenyl group, and x is an integer of at least 2 representing a number of repeating units, wherein Ph is an aromatic group such as a phenyl group, and x is an integer of at least 2 representing a number of repeating units. The aromatic vinyl compound-ethylene random copolymer according to claim 11, wherein the aromatic vinyl compound content is at least 5% and less than 20% by molar fraction, the weight average molecular weight as calculated as polystyrene is at least 60,000, and the molecular weight distribution (Mw/Mn) is at most 6; or wherein the aromatic vinyl compound content is from 20 to 99.9% by molar fraction, the weight average molecular weight as calculated as polystyrene is at least 30,000, and the molecular weight distribution (Mw/Mn) is at most 6. An aromatic vinyl compound-propylene random copolymer, wherein the aromatic vinyl compound content is from 5 to 99.9 mol% and the molecular weight distribution (Mw/Mn) is at most 6. The aromatic vinyl compound-propylene random copolymer according to claim 16, characterized in that the chain structure of the units of the aromatic vinyl compound has an isotactic stereoregularity and/or the chain structure of the propylene units has an isbtactic stereoregularity. A method for producing an aromatic vinyl compound ethylene alternating copolymer, wherein polymerization is carried out at a polymerization temperature of from -20 to +40°C by the method as defined in Claim 8. An aromatic vinyl compound-ethylene alternating copolymer, wherein alternating index λ is at least 70, and the isotactic diad (meso diad) index m is at least 0.95. An aromatic vinyl compound-ethylene alternating copolymer, which has a weight average molecular weight of at least 10,000; and/or which has a melting point of at least 130°C, preferably at least 150°C, and lower than 210°C, as obtained by the DSC measurement; and/or wherein the aromatic vinyl compound content is from 46 to 54 mol%.

Inventors: ARAI TORU, OTSU TOSHIAKI, SUZUKI SHIGERU, ARAI, TORU, OTSU, TOSHIAKI, SUZUKI, SHIGERU
Applicants: DENKI KAGAKU KOGYO KK, DENKI KAGAKU KOGYO KABUSHIKI KAISHA
Application year: 1998
Main classification: C08F12
IPC codes: C07F17, C08F12, C08F4