Catalyst composition for preparing vinyl polymer by high-temperature solution method and method for preparing vinyl polymer by using catalyst composition

Abstract

The present invention relates to a catalyst composition for preparing a vinyl polymer, the catalyst composition being suitable for use in a high-temperature solution process, and a method for preparing a vinyl polymer using the catalyst composition. According to the present invention, the low-density ethylene homopolymer or ethylene-alpha-olefin copolymer having a wide molecular weight distribution and bimodal distribution can be prepared with high activity during the solution polymerization process performed under a high temperature condition.

Description

Technical Field

[0001] The present invention relates to a catalyst composition for preparing vinyl polymer by a high-temperature solution process and a method for preparing vinyl polymer by using the catalyst composition. Background Art

[0002] Metallocene catalysts have been used to produce ethylene homopolymers and α-olefins. Metallocenes are currently used industrially in the production of polypropylene and polyethylene. Metallocenes are typically produced using cyclopentadienyl catalyst systems with varying substitution patterns.

[0003] Several metallocene catalysts have been described for use in solution polymerization to prepare polyethylene homopolymers or copolymers.

[0004] For example, US Pat. No. 6,313,240 discloses a catalyst system comprising a hafnium ene catalyst complex derived from a biscyclopentadienyl hafnium organometallic compound (A), which comprises: 1) one or more substituted cyclopentadienyl ligands or fused pentadienyl ligands substituted with an aryl group and having no additional substituents on the ligands, 2) a fused pentadienyl ligand which is substituted with an aryl group or is unsubstituted, and 3) a covalent bridge connecting the two cyclopentadienyl ligands.

[0005] The bridge may be a single carbon substituted with two aryl groups, and each aryl group is substituted with a C1-C20 hydrocarbyl or hydrocarbylsilyl group.

[0006] Additionally, the catalyst system includes an activated cocatalyst that is a precursor ionic compound comprising a Group 13 anion substituted with a tetraaryl halide.

[0007] In recent years, in order to develop polymers with a bimodal distribution, research has been conducted on the use of two types of catalysts: a low molecular weight catalyst with good processing performance and a high molecular weight catalyst that is easy to control the physical properties of the polymer. Since the high molecular weight polymer determines the physical properties in part, while the low molecular weight polymer determines the processing performance in part, the preparation of bimodal polymers generally uses two types of catalysts. In addition, there is a method for preparing low molecular weight polymers using hydrogen, but this method has the problem of reduced catalytic activity. In addition, there have been attempts to control the bimodal distribution by setting up additional reactors, but this will result in increased costs. To solve the above problems, a catalyst that still has high catalytic activity at high temperatures and can produce low molecular weight polymers is needed, and the control of the bimodal distribution can be achieved by combining two types of catalysts.

[0008] In addition, since low molecular weight polymers have the potential to produce ideal polyethylene waxes, the importance of independently developable catalysts is becoming increasingly prominent.

[0009] Meanwhile, metallocene-based catalysts have been reported, in which a transition metal is linked to a cross-linked Cp-Flu ligand. These catalysts exhibit high catalytic activity and are capable of producing high molecular weight polymers in ethylene homopolymerization or ethylene-α-olefin copolymerization under solution polymerization conditions. US Pat. No. 6,559,253 describes an example structure in which an unsubstituted fluorene is attached to a bridge substituted with a diphenyl group and a cyclopentadienyl ligand. Furthermore, US Pat. No. 6,121,396 describes a Cp-Flu ligand structure with a diphenylmethylene bridge substituted with one or more electron-donating groups.

[0010] This type of catalyst exhibits significantly improved reactivity towards α-olefins due to its low steric hindrance. However, commercial application of low molecular weight polymers still faces many difficulties. Therefore, the search for a catalyst system that is economically viable and ensures a more competitive performance in terms of the properties required for commercial catalysts, namely the ability to produce polymers with excellent activity at high temperatures and good processability, is becoming increasingly important. Summary of the Invention

[0011] Technical issues

[0012] The present inventors have conducted research to overcome the problems in the prior art and have found that when two transition metal compounds with specific structures are mixed, low-density ethylene homopolymers or copolymers of ethylene and α-olefins can be prepared with high activity in a solution polymerization process carried out at high temperature, which have a large molecular weight distribution and a bimodal distribution.

[0013] Therefore, an object of the present invention is to provide a catalyst composition for preparing an ethylene-based polymer, which catalyst composition can produce a low-density ethylene homopolymer or a copolymer of ethylene and an α-olefin with a large molecular weight distribution and a bimodal distribution in a solution polymerization process carried out at a high temperature with high activity, and a method for preparing an ethylene-based polymer using the catalyst composition.

[0014] Technical Solution

[0015] In one general aspect, a catalyst composition for preparing an ethylene-based polymer includes: a first transition metal compound as shown in Chemical Formula 1; a second transition metal compound as shown in Chemical Formula 2; and a cocatalyst selected from aluminum compounds, boron compounds, or mixtures thereof.

[0016] [Chemical Formula 1]

[0017]

[0018] [Chemical Formula 2]

[0019]

[0020] in

[0021] M 1 It is a transition metal in Group 4 of the periodic table;

[0022] R 1 to R 4 Each is independently a C1-C20 alkyl group or a C6-C20 aryl group;

[0023] R 5 、R 6 、R 15 and R 16 are each independently a C6-C20 aryl group, and the R 5 、R 6 、R 15 and R 16 The aryl group in may be further substituted by a C1-C20 alkyl group;

[0024] R 11 and R 12 Each is independently hydrogen or C1-C20 alkyl;

[0025] X 1 、X 2 、X 11 and X 12 Each is independently halogen, C1-C20 alkyl, C3-C20 cycloalkyl, C6-C20 aryl, C6-C20 arylC1-C20 alkyl, (C1-C20 alkylC6-C20 aryl) C1-C20 alkyl, C1-C20 alkoxy, C6-C20 aryloxy, C1-C20 alkylC6-C20 aryloxy, C1-C20 alkoxyC6-C20 aryloxy, -OSiR a R b R c 、-SR d 、-NR e R f 、-PR g R h or C1-C20 alkylene;

[0026] R a to R d Each is independently a C1-C20 alkyl group, a C6-C20 aryl group, a C6-C20 arylC1-C20 alkyl group, a C1-C20 alkylC6-C20 aryl group or a C3-C20 cycloalkyl group;

[0027] R e to R hEach is independently a C1-C20 alkyl group, a C6-C20 aryl group, a C6-C20 arylC1-C20 alkyl group, a C1-C20 alkylC6-C20 aryl group or a C3-C20 cycloalkyl group;

[0028] When X 1 and X 2 When one of is C1-C20 alkylene, the other is absent; and

[0029] When X 11 and X 12 When one of the groups is a C1-C20 alkylene group, the other group is absent.

[0030] In another general aspect, a method of preparing a vinyl polymer comprises polymerizing a vinyl monomer in the presence of a catalyst composition to prepare the vinyl polymer.

[0031] Beneficial effects

[0032] Catalyst composition according to the present invention can, while maintaining high catalytic activity, prepare low-density polymers with good copolymerization reactivity and wide molecular weight distribution with other olefins by combining the transition metal compound with specific structure in high-temperature solution polymerization. In addition, catalyst composition according to the present invention can also prepare low-density vinyl polymers with large molecular weight distribution and bimodal distribution, and prepared vinyl polymers have excellent processing characteristics. Therefore, catalyst composition according to the present invention can be used for preparing ethylene homopolymers with various physical properties and copolymers with alpha-olefins. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the GPC chart of the copolymer prepared in Example 2.

[0034] Best Practice

[0035] The present invention will be described in more detail. Unless otherwise defined, technical and scientific terms used in the present invention have the common meanings understood by those skilled in the art to which the present invention belongs. In the following description, descriptions of known functions and structures will be omitted to avoid obscuring the present invention.

[0036] Singular forms used in this specification may also include plural forms unless the context indicates otherwise.

[0037] The term "comprising" used in this specification is an open description, which is equivalent to "providing", "including", "having" or "characterized by", and does not exclude elements, materials or methods that are not further listed.

[0038] As used herein, "alkyl" refers to a monovalent, straight-chain or branched, saturated hydrocarbon group consisting solely of carbon and hydrogen atoms. Examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, octyl, and nonyl.

[0039] As used herein, "aryl" refers to an organic group derived from an aromatic hydrocarbon by removing a hydrogen atom, and includes monocyclic or fused ring systems containing 4 to 7 ring atoms, preferably 5 or 6 ring atoms, per ring, and even multiple aryl groups connected by single bonds. The fused ring system may include an aliphatic ring, such as a saturated or partially saturated ring, and must include one or more aromatic rings. In addition, the aliphatic ring may also contain nitrogen, oxygen, sulfur, carbonyl, etc. Specific examples of aryl include, but are not limited to, phenyl, naphthyl, biphenyl, indenyl, fluorenyl, phenanthrenyl, anthracenyl, triphenylene, pyrenyl, chrysyl, naphthacene, and 9,10-dihydroanthracenyl.

[0040] The term "cycloalkyl" as used herein refers to a monovalent saturated carbocyclic group consisting of one or more rings. Examples of cycloalkyl include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cycloheptyl.

[0041] "Halo" or "halogen" described in the present specification refers to a fluorine, chlorine, bromine or iodine atom.

[0042] The "alkoxy" described in this specification refers to -O-(alkyl), including -OCH3, -OCH2CH3, -O(CH2)2CH3, -O(CH2)3CH3, -O(CH2)4CH3, -O(CH2)5CH3, etc., wherein "alkyl" is as defined above.

[0043] The "aryloxy group" described in the present specification refers to an -O-aryl group, wherein the "aryl group" is as defined above.

[0044] "Alkylene" refers to a straight or branched chain saturated divalent hydrocarbon group having a valence of 2 at a single carbon atom.

[0045] In this specification, the (co)polymer includes the meanings of homopolymer and copolymer.

[0046] In the present specification, unless otherwise defined, “copolymerization” may refer to block copolymerization, random copolymerization, graft copolymerization or alternating copolymerization, and “copolymer” may refer to block copolymer, random copolymer, graft copolymer or alternating copolymer.

[0047] Hereinafter, the present invention will be described in detail.

[0048] An exemplary embodiment of the present invention provides a catalyst composition for preparing an ethylene-based polymer in a high-temperature solution process, and the catalyst composition for preparing an ethylene-based polymer according to an exemplary embodiment includes: a first transition metal compound as shown in Chemical Formula 1; a second transition metal compound as shown in Chemical Formula 2; and a co-catalyst selected from an aluminum compound, a boron compound, or a mixture thereof:

[0049] [Chemical Formula 1]

[0050]

[0051] [Chemical Formula 2]

[0052]

[0053] in

[0054] M 1 It is a transition metal in Group 4 of the periodic table;

[0055] R 1 to R 4 Each is independently a C1-C20 alkyl group or a C6-C20 aryl group;

[0056] R 5 、R 6 、R 15 and R 16 Each is independently a C6-C20 aryl group, and the aryl group in R5, R6, R15 and R16 may be further substituted by a C1-C20 alkyl group;

[0057] R 11 and R 12 Each is independently hydrogen or C1-C20 alkyl;

[0058] X 1 、X 2 、X 11 and X 12 Each is independently halogen, C1-C20 alkyl, C3-C20 cycloalkyl, C6-C20 aryl, C6-C20 arylC1-C20 alkyl, (C1-C20 alkylC6-C20 aryl)C1-C20 alkyl, C1-C20 alkoxy, C6-C20 aryloxy, C1-C20 alkylC6-C20 aryloxy, C1-C20 alkoxyC6-C20 aryloxy, -OSiR a R b R c 、-SR d 、-NR e R f 、-PR g R hor C1-C20 alkylene;

[0059] R a to R d Each is independently a C1-C20 alkyl group, a C6-C20 aryl group, a C6-C20 arylC1-C20 alkyl group, a C1-C20 alkylC6-C20 aryl group or a C3-C20 cycloalkyl group;

[0060] R e to R h Each is independently a C1-C20 alkyl group, a C6-C20 aryl group, a C6-C20 arylC1-C20 alkyl group, a C1-C20 alkylC6-C20 aryl group or a C3-C20 cycloalkyl group;

[0061] When X 1 and X 2 When one of is C1-C20 alkylene, the other is absent; and

[0062] When X 11 and X 12 When one of the groups is a C1-C20 alkylene group, the other group is absent.

[0063] Because the catalyst composition for preparing vinyl polymers according to the exemplary embodiment satisfies the combination of a first transition metal compound, a second transition metal compound, and a co-catalyst having a specific structure, vinyl polymers having a bimodal distribution can be prepared with high activity in a high-temperature solution polymerization process. Furthermore, because the catalyst composition for preparing vinyl polymers according to the exemplary embodiment satisfies the combination of the above-mentioned configurations, low-density vinyl polymers having high activity and a large molecular weight distribution can be prepared. Furthermore, because the catalyst composition for preparing vinyl polymers according to the exemplary embodiment satisfies the combination of the above-mentioned configurations, low-density vinyl polymers having a bimodal distribution and a large molecular weight distribution can be prepared under high-temperature and high-pressure polymerization conditions.

[0064] The Group 4 transition metal may include titanium (Ti), zirconium (Zr), hafnium (Hf), and the like, specifically, zirconium (Zr) or hafnium (Hf).

[0065] In Chemical Formula 1, M 1 Can be Zr or Hf; R 1 to R 4 R 5 and R 6 may be each independently a C6-C20 aryl group, and R 5 and R 6 The aryl group in X may be further substituted by a C1-C20 alkyl group; 1 and X2 Each of them can independently be halogen, C1-C20 alkyl, C6-C20 aryl, or C6-C20 arylC1-C20 alkyl.

[0066] Specifically, in Chemical Formula 1, M 1 Can be Hf; R 1 to R 4 R 5 and R 6 may be each independently a C6-C12 aryl group, and R 5 and R 6 The aryl group in X may be further substituted by a C1-C10 alkyl group; 1 and X 2 Each of them can independently be halogen, C1-C10 alkyl, C6-C12 aryl or C6-C12 arylC1-C10 alkyl.

[0067] In chemical formula 2, R 11 and R 12 R may independently be hydrogen or C1-C20 alkyl; 15 and R 16 may be independently C6-C20 aryl, and R 15 and R 16 The aryl group in X may also be substituted by a C1-C20 alkyl group; 11 and X 12 They may independently be halogen, C1-C20 alkyl, C6-C20 aryl, or C6-C20 arylC1-C20 alkyl.

[0068] Specifically, in Chemical Formula 2, R 11 and R 12 R 15 and R 16 may be each independently a C6-C12 aryl group, and R 15 and R 16 The aryl group in X may be further substituted by a C1-C10 alkyl group; and 11 and X 12 Each of them can independently be halogen, C1-C10 alkyl, C6-C12 aryl or C6-C12 arylC1-C10 alkyl.

[0069] More specifically, in Chemical Formula 1, M 1 Can be Hf; R 1 to R 4 They may be the same C1-C10 alkyl or C6-C12 aryl groups; R 5 and R 6 Can be independently , where R 21 is a C1-C10 alkyl group; and a is an integer from 0 to 5; X 1 and X 2 They may each independently be halogen, C1-C6 alkyl, C6-C12 aryl, or C6-C12 arylC1-C6 alkyl.

[0070] More specifically, in Chemical Formula 2, R 11 and R 12 may be the same as each other and be hydrogen or C1-C10 alkyl; R 15 and R 16 Can be independently , where R 21 is a C1-C10 alkyl group; and a is an integer from 0 to 5; and X 11 and X 12 They may each independently be halogen, C1-C6 alkyl, C6-C12 aryl, or C6-C12 arylC1-C6 alkyl.

[0071] The first transition metal compound may be [1-(η5-cyclopentadien-1-yl)-1-(η5-2,7-dimethylaminofluorenyl)-1,1-diphenylmethane]dichlorohafnium, [1-(η5-cyclopentadien-1-yl)-1-(η5-2,7-dimethylaminofluorenyl)-1,1-diphenylmethane]dibenzylhafnium, or [1-(η5-cyclopentadien-1-yl)-1-(η5-2,7-dimethylaminofluorenyl)-1,1-diphenylmethane]dimethylhafnium; and

[0072] The second transition metal compound may be [1-(η5-cyclopentadien-1-yl)-1-(η5-fluorenyl)-1,1-diphenylmethane]dichlorohafnium, [1-(η5-cyclopentadien-1-yl)-1-(η5-fluorenyl)-1,1-diphenylmethane]dibenzylhafnium, [1-(η5-cyclopentadien-1-yl)-1-(η5-fluorenyl)-1,1-diphenylmethane]dimethylhafnium, [1-(η5-cyclopentadien-1-yl)-1-(η5-fluorenyl)-1,1-diphenylmethane]dimethylhafnium, [1-(η5 -cyclopentadien-1-yl)-1-(η5-2,7-di-tert-butylfluorenyl)-1,1-diphenylmethane]dichlorohafnium, [1-(η5-cyclopentadien-1-yl)-1-(η5-2,7-di-tert-butylfluorenyl)-1,1-diphenylmethane]dibenzyl, or [1-(η5-cyclopentadien-1-yl)-1-(η5-2,7-di-tert-butylfluorenyl)-1,1-diphenylmethane]dimethylhafnium.

[0073] Since the first transition metal compound of Chemical Formula 1 has a Group 4 transition metal as a central metal and has a fluorene ligand in which a bulky amine substituent with an electron-donating function is introduced at the 2- and 7-positions away from the active site, it can be used as a catalyst with high activity in high-temperature solution polymerization and can produce a low-molecular-weight vinyl polymer.

[0074] The first transition metal compound shown in Chemical Formula 1 is combined with the second transition metal compound shown in Chemical Formula 2 to produce a high molecular weight polymer and has high activity in high-temperature solution polymerization. It can also prepare a low-density vinyl polymer with a large molecular weight distribution and a bimodal distribution, and has excellent physical properties and excellent processing performance.

[0075] In order to prepare a low-density vinyl polymer having a large molecular weight distribution and a bimodal distribution, the first transition metal compound represented by Chemical Formula 1 and the second transition metal compound represented by Chemical Formula 2 can be used in a molar ratio of 1:0.2 to 1:1.5. Specifically, the first transition metal compound represented by Chemical Formula 1 and the second transition metal compound represented by Chemical Formula 2 can be mixed in a molar ratio of 1:0.5 to 1:1.5 or 1:0.5 to 1:1.

[0076] The co-catalyst can act as a scavenger, removing impurities that act as catalyst poisons while activating the transition metal compound.

[0077] The aluminum compound used as a co-catalyst can be selected from one or two or more of aluminoxane compounds and organoaluminum compounds, wherein the aluminoxane compound can be represented by the following chemical formula A or B, and the organoaluminum compound can be represented by the following chemical formula C:

[0078] [Chemical Formula A]

[0079] (R a )2Al-(-O(R a )-) p -(R a )2

[0080] [Chemical Formula B]

[0081] (-Al(R a )-O-) q

[0082] [Chemical Formula C]

[0083] (R b ) r Al(E) 3-r

[0084] in

[0085] R ais a C1-C20 alkyl group; p and q are each independently an integer from 5 to 20; R b is a C1-C20 alkyl group; E is hydrogen or halogen; and r is an integer from 1 to 3.

[0086] In chemical formulas A and B, R a It may be methyl or isobutyl.

[0087] Examples of aluminoxane compounds may include methylaluminoxane, modified methylaluminoxane and tetraisobutylaluminoxane; examples of organoaluminum compounds may include trialkylaluminums such as trimethylaluminum, triethylaluminum, tripropylaluminum, triisobutylaluminum, trihexylaluminum and trioctylaluminum; dialkylaluminum chlorides such as dimethylaluminum chloride, diethylaluminum chloride, dipropylaluminum chloride, diisobutylaluminum chloride and dihexylaluminum chloride; alkylaluminum dichlorides such as methylaluminum dichloride, ethylaluminum dichloride, propylaluminum dichloride, isobutylaluminum dichloride and hexylaluminum dichloride; dialkylaluminum hydrides such as dimethylaluminum hydride, diethylaluminum hydride, dipropylaluminum hydride, diisobutylaluminum hydride and dihexylaluminum hydride;

[0088] Preferably, the aluminum compound may be one or two or more selected from methylaluminoxane, modified methylaluminoxane, tetraisobutylaluminoxane, trimethylaluminum, triethylaluminum, trioctylaluminum and triisobutylaluminum.

[0089] The boron compound used as a co-catalyst may be selected from the boron compounds represented by the following chemical formulae D to F:

[0090] [Chemical Formula D]

[0091] B(R c )3

[0092] [Chemical Formula E]

[0093] [R d ] + [B(R c )4] -

[0094] [Chemical Formula F]

[0095] [(R e ) s [EN] + [B(R c )4] -

[0096] in

[0097] B is a boron atom; R cis a phenyl group, and the phenyl group may be further substituted by 3 to 5 substituents selected from fluorine atoms, C1-C20 alkyl groups which are unsubstituted or substituted by fluorine atoms, and C1-C20 alkoxy groups which are unsubstituted or substituted by fluorine atoms; R d is a C5-C7 aryl group or a C1-C20 alkyl group, a C6-C20 aryl group, or a C6-C20 aryl group or a C1-C20 alkyl group, for example, a triphenylmethyl group; Z is a nitrogen atom or a phosphorus atom; R e is a C1-C20 alkyl group or an aniline group substituted on the nitrogen atom by two C1-C10 alkyl groups; and s is an integer of 2 or 3.

[0098] Examples of boron compounds may include dimethylphenylammonium tetra(phenyl)borate, tritylammonium tetra(phenyl)borate, dimethylphenylammonium tetra(pentafluorophenyl)borate, tritylammonium tetra(pentafluorophenyl)borate, trimethylammonium tetra(phenyl)borate, triethylammonium tetra(phenyl)borate, tripropylammonium tetra(phenyl)borate, tributylammonium tetra(phenyl)borate, trimethylammonium tetra(pentafluorophenyl)borate, triethylammonium tetra(pentafluorophenyl)borate, tripropylammonium tetra(pentafluorophenyl)borate, tributylammonium tetra(pentafluorophenyl)borate, tetra(phenyl)borate aniline salt, tetra(pentafluorophenyl)borate aniline salt, tetra(pentafluorophenyl)borate pyridinium salt, and the like.

[0099] Specifically, the co-catalyst may be a combination of an organoaluminum compound and a boron compound.

[0100] More specifically, the co-catalyst may be a combination of an organoaluminum compound of Formula C and a boron compound of Formula E or F.

[0101] The co-catalyst may be a combination of a trialkylaluminum compound and a boron compound, wherein the trialkylaluminum compound may be selected from one or two or more of trimethylaluminum, triethylaluminum, tripropylaluminum, triisobutylaluminum, trihexylaluminum and trioctylaluminum, and the boron compound may be selected from one or two or more of dimethylphenylammonium tetra(phenyl)borate, tritylammonium tetra(phenyl)borate, dimethylphenylammonium tetra(pentafluorophenyl)borate, tritylammonium tetra(pentafluorophenyl)borate, trimethylammonium tetra(phenyl)borate, triethylammonium tetra(pentafluorophenyl)borate, tripropylammonium tetra(phenyl)borate, tributylammonium tetra(pentafluorophenyl)borate, trimethylammonium tetra(pentafluorophenyl)borate, triethylammonium tetra(pentafluorophenyl)borate, tripropylammonium tetra(pentafluorophenyl)borate, tributylammonium tetra(pentafluorophenyl)borate, aniline tetra(phenyl)borate, aniline tetra(pentafluorophenyl)borate and pyridinium tetra(pentafluorophenyl)borate.

[0102] The co-catalyst may be used in an appropriate amount so that activation of the first transition metal compound represented by Chemical Formula 1 and the second transition metal compound represented by Chemical Formula 2 can be sufficiently performed.

[0103] For example, when an aluminum compound and a boron compound are used as co-catalysts at the same time, the ratio of the total amount of transition metal compound (first transition metal compound + second transition metal compound) to the co-catalyst is preferably in the range of 1:(10-3,000):(1-100), more preferably 1:(100-1,000):(3-10), based on the molar ratio of transition metal (M): aluminum atom (Al): boron atom (B).

[0104] When the ratio of the total amount of the transition metal compound to the co-catalyst exceeds the above range, the amount of co-catalyst used may be relatively small, which may result in incomplete activation of the transition metal compound and insufficient activation of the transition metal compound catalyst. Alternatively, when the amount of the catalyst exceeds the above range, production costs may be significantly increased. Within the above range, excellent catalytic activity for the preparation of vinyl polymers can be exhibited, and this ratio range may vary depending on the reaction purity.

[0105] The catalyst composition may further comprise one or two or more C5-C12 aliphatic hydrocarbon solvents selected from pentane, hexane, heptane, octane, isooctane, nonane, decane, dodecane, cyclohexane and methylcyclohexane as a reaction solvent.

[0106] Since the catalyst composition exists in a uniform form in the polymerization reactor, it is preferable to apply the composition to a high-temperature solution polymerization process at 110° C. or higher.

[0107] Another exemplary embodiment of the present invention provides a method for preparing a vinyl polymer by polymerizing a vinyl monomer in the presence of a catalyst composition.

[0108] The vinyl monomer is ethylene or an α-olefin. Specifically, when preparing an ethylene homopolymer, ethylene is used alone as a monomer. When preparing a copolymer of ethylene and an α-olefin, one or two or more selected from (C3-C18) α-olefins, (C5-C20) cycloolefins, styrene, and derivatives thereof can be used as comonomers copolymerized with ethylene. The (C3-C18) α-olefin can be preferably selected from the group consisting of propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-octadecene. The (C5-C20) cycloolefin can be preferably selected from the group consisting of cyclopentene, cyclohexene, norbornene, and phenylnorbornene. Styrene and derivatives thereof can be preferably selected from styrene, α-methylstyrene, p-methylstyrene, and 3-chloromethylstyrene. More preferably, the α-olefin is one or two or more of 1-butene, 1-hexene, 1-octene and 1-decene.

[0109] The preparation method can be carried out by contacting the catalyst composition for preparing an ethylene-based polymer according to an exemplary embodiment with ethylene or a comonomer (if necessary) in the presence of a suitable organic solvent. The first transition metal compound, the second transition metal compound, and the co-catalyst component can be added to the reactor separately or premixed before addition. There are no particular limitations on the mixing conditions of the components, such as the order of addition, temperature, or concentration.

[0110] The polymerization reaction can be carried out at a temperature of 110 to 170° C., particularly at a temperature of 120 to 160° C. and a pressure of 10 to 100 bar, more particularly at a temperature of 130 to 150° C. and a pressure of 15 to 50 bar.

[0111] In addition, the preparation method can be carried out in a C5-C12 aliphatic hydrocarbon solvent. Specifically, the C5-C12 aliphatic hydrocarbon solvent can be one or two or more of pentane, hexane, heptane, octane, isooctane, nonane, decane, dodecane, cyclohexane and methylcyclohexane, preferably hexane, cyclohexane or a mixture thereof.

[0112] Since the preparation method of the exemplary embodiment does not use toluene, a co-solvent commonly used in conventional copolymer preparation, there is no need to perform a toluene solvent removal step, thereby making the preparation method more economical.

[0113] The ethylene-based polymer prepared according to the exemplary embodiment may be an ethylene homopolymer.

[0114] The ethylene-based polymer prepared according to the exemplary embodiment may be a copolymer of ethylene and an α-olefin. The copolymer of ethylene and an α-olefin may contain 50 wt% or more of ethylene, preferably 60 wt% or more of ethylene, and more preferably 60-99 wt% of ethylene. The density of the copolymer of ethylene and an α-olefin may be 0.900 g / cm³ or less, preferably 0.850 g / cm³. 3 -0.900 g / cm 3 , the molecular weight distribution (Mw / Mn) can be 4 or higher, preferably 4.5-8.0, and bimodal distribution.

[0115] Generally speaking, a wider molecular weight distribution and lower shear rates can reduce density, thereby improving processability, but physical properties such as strength can be reduced. However, when the molecular weight distribution is broad and bimodal, physical properties can be enhanced while also improving processability, depending on the catalyst type. DETAILED DESCRIPTION

[0116] The present invention is further described below by way of the following examples, but the scope of the present invention is not limited thereto.

[0117] [Materials and Analytical Instruments]

[0118] All the following synthetic reactions were carried out under an inert atmosphere such as nitrogen or argon, and standard Schlenk techniques and glove box techniques were used. Synthetic solvents, such as tetrahydrofuran (THF), n-hexane, n-pentane, diethyl ether, and dichloromethane (CH2Cl2), were passed through an activated alumina column to remove water and then placed on activated molecular sieves for storage until use. Unless otherwise stated, most reagents were purchased from Sigma-Aldrich, TCI, Alfa, and Strem. Synthetic ligands and catalysts 1 H NMR analysis was performed using a Bruker 500 MHz at room temperature.

[0119] [Determination of physical properties]

[0120] The polymers after polymerization were analyzed using the following methods:

[0121] 1. Polymerization activity

[0122] The polymerization activity (Kg / g cat) was calculated as the weight ratio of polymer produced per unit amount of catalyst.

[0123] 2. Melt flow index (MI)

[0124] Melt flow index (MI) was measured according to ASTM D1238 at 190°C and a load of 2.16 kg.

[0125] 3. Density

[0126] Density was measured in a density gradient column using ASTM D1505.

[0127] 4. Molecular weight distribution

[0128] The molecular weight distribution is calculated by measuring the weight-average molecular weight (Mw) and number-average molecular weight (Mn). The analysis is performed using gel permeation chromatography (GPC) at 150°C using 1,2,4-trichlorobenzene as the solvent, and then dividing the measured Mw by Mn.

[0129] [Catalyst Preparation Method 1] Preparation of [1-(η5-cyclopentadienyl)-1-(η5-fluorenyl)-1,1-diphenylmethane]dichlorohafnium (CAT-1)

[0130] [1-(η5-cyclopentadienyl)-1-(η5-fluorenyl)-1,1-diphenylmethane]dichlorohafnium (CAT-1) was synthesized according to the method described in A. Razavi, JL Atwood, J. Organometallic. Chen, 459 (1993), 117-123.

[0131] 1 H NMR (500 MHz, chloroform-d) δ 8.19 (d, J = 8.5 Hz, 2H), 7.95 (d, J = 8.3Hz, 2H), 7.88 (d, J = 8.5 Hz, 2H), 7.55 (t, J = 8.0 Hz, 2H), 7.44 (t, J = 8.2Hz, 2H), 7.31 (m, 4H), 7.01 (t, J = 8.1 Hz, 2H), 6.47 (d, J = 7.1 Hz, 2H), 6.33 (s, 2H), 5.75 (s, 2H)

[0132] [Catalyst Preparation Method 2] Preparation of [1-(η5-cyclopentadien-1-yl)-1-(η5-2,7-di-tert-butylfluorenyl)-1,1-diphenylmethane]dichlorohafnium (CAT-2)

[0133] Step 1: Preparation of 1-(cyclopentadien-1-yl)-1-(2,7-di-tert-butylfluorenyl)-1,1-diphenylmethane (a1)

[0134]

[0135] Dissolve 2,7-di-tert-butylfluorene (12 g, 43.1 mmol) in THF (87 mL), add n-butyllithium (n-BuLi, 1.6 M in n-hexane, 27.1 mL, 43.1 mmol), and stir at room temperature. After 3 hours, add 6,6-diphenylfulvene (10 g, 43.1 mmol). Stir the reaction mixture for 16 hours before quenching it with aqueous NH4Cl (40 mL). The product was extracted to obtain an organic layer, dried over MgSO4, filtered, and concentrated under reduced pressure to obtain a yellow solid. This solid was washed with ethanol to afford ligand a1 (20 g, 93% yield) as a white solid.

[0136] 1 H NMR (500 MHz, chloroform-d) δ 6.21–7.35 (m, 20H), 5.45 (s, 1H), 3.01 (m, 1H), 1.14 (s, 18H)

[0137] Step 2: Preparation of [1-(η5-cyclopentadien-1-yl)-1-(η5-2,7-di-tert-butylfluorenyl)-1,1-diphenylmethane]dichlorohafnium (CAT-2)

[0138]

[0139] 1-(Cyclopentadien-1-yl)-1-(2,7-di-tert-butylfluorenyl)-1,1-diphenylmethane (a1, 5 g, 9.82 mmol) was dissolved in 60 mL of diethyl ether. n-Butyllithium (nBuLi, 1.6 M in n-hexane, 13.5 mL, 21.6 mmol) was added and stirred for 16 hours. After the reaction, the ether was removed by vacuum drying, n-hexane was added, and the mixture was decanted and decompressed. In a glove box, the lithiated intermediate a2 (5.1 g, 9.79 mmol) and HfCl4 (3.13 g, 9.79 mmol) were aliquoted and dissolved in 80 mL of diethyl ether. The mixture was stirred at room temperature for 16 hours, the ether was removed by vacuum drying, and 80 mL of toluene was added. The reaction mixture was heated at 50°C for 2 hours to precipitate the generated LiCl and dried. The filtrate was dried under vacuum and crystallized to yield 4.4 g of yellow crystals of CAT-2 (recrystallized from toluene, yield: 60%).

[0140] [Catalyst Preparation Method 3] Preparation of [1-(η5-cyclopentadien-1-yl)-1-(η5-2,7-dimethylaminofluorenyl)-1,1-diphenylmethane]dichlorohafnium (CAT-3)

[0141] Step 1: Preparation of 2,7-dimethylaminofluorene (b1)

[0142]

[0143] NaBH₄ (7.7 g, 203.8 mmol) and 2,7-diaminofluorene (5 g, 25.4 mmol) were added to a Schlenk flask and maintained at 0°C. Ethanol (50 mL) and acetic acid (7.27 mL, 127 mmol) were added, followed by paraformaldehyde (11.5 g, 382 mmol). After 16 hours, saturated aqueous NH₂CO₃ solution and diethyl ether were added, and the mixture was extracted three times. The organic layer was collected, dried over MgSO₄, filtered, and decompressed. Recrystallization from hexane afforded 2,7-dimethylaminofluorene (b1) as a yellow solid (5.1 g, 80%).

[0144] 1H NMR (500 MHz, chloroform-d) δ 7.50 (d, J = 8.5 Hz, 2H), 6.93 (d, J = 2.0Hz, 2H), 6.76 (d, J = 7.7 Hz, 2H), 3.81 (s, 2H), 2.98 (s, 12H).

[0145] Step 2: Preparation of 1-(cyclopentadien-1-yl)-1-(2,7-di-n-butylfluorenyl)-1,1-diphenylmethane (b2)

[0146]

[0147] Dissolve 2,7-dimethylaminofluorene (b1, 12 g, 43.1 mmol) in THF (87 mL). Add n-butyllithium (nBuLi, 1.6 M in n-hexane, 27.1 mL, 43.1 mmol) and stir at room temperature. After 3 hours, add 6,6-diphenylfulvene (10 g, 43.1 mmol). Stir the reaction mixture for 16 hours before quenching it with aqueous NH4Cl (40 mL). The organic layer was extracted, dried over MgSO4, filtered, and concentrated under reduced pressure to yield a yellow solid. This solid was washed with ethanol to afford ligand b2 (20 g, 91% yield) as a brown solid.

[0148] Step 3: Preparation of [1-(η5-cyclopentadien-1-yl)-1-(η5-2,7-dimethylaminofluorenyl)-1,1-diphenylmethane]dichlorohafnium (CAT-3)

[0149]

[0150] 1-(Cyclopentadien-1-yl)-1-(2,7-dimethylaminofluorenyl)-1,1-diphenylmethane (b2, 5 g, 9.82 mmol) was dissolved in 60 mL of diethyl ether. n-Butyllithium (nBuLi, 1.6 M in n-hexane, 13.5 mL, 21.6 mmol) was added and stirred for 16 hours. After completion of the reaction, the diethyl ether was removed by vacuum drying, n-hexane was added, and the mixture was decanted and decompressed. In a glove box, the lithiated intermediate b3 (5.1 g, 9.79 mmol) and HfCl4 (3.13 g, 9.79 mmol) were separately dissolved in 80 mL of diethyl ether. The mixture was stirred at room temperature for 16 hours, the diethyl ether was removed by vacuum drying, and 80 mL of toluene was added. The reaction mixture was heated at 50°C for 2 hours to precipitate the generated LiCl and dried. The filtrate was dried under vacuum to obtain 4.5 g of yellow crystals of CAT-3 (recrystallized from toluene, yield: 60%).

[0151] Example 1: Preparation of ethylene and 1-octene copolymer

[0152] At room temperature, 1 L of hexane and 2 mL of triisobutylaluminum (TIBA, 1 M in n-hexane) were injected into a 4 L reactor, followed by 100 mL of 1-octene. In a glove box, catalysts CAT-1 (3.9 μmol) and CAT-3 (3.9 μmol) were weighed, mixed with 2 mL of TIBA (0.1 M in n-hexane), and 5 mL of toluene was added and injected into the reactor inlet. In the glove box, 19.5 μmol of trityltetrakis(pentafluorophenyl)borate was mixed with 5 mL of toluene and injected into the reactor inlet. The reactor temperature was raised to 140°C, and high-pressure nitrogen was used to push the inlet solution into the reactor. Ethylene was injected at 21 bar for 15 minutes. Results showed that the initial temperature was proportional to the activity. After polymerization was completed, the reactor was cooled to 30°C and slowly vented to remove the ethylene pressure. The reaction product was washed with ethanol and acetone, filtered, and dried under vacuum. The physical properties of the resulting polymer are shown in Table 1.

[0153] Example 2

[0154] The polymerization reaction was carried out in the same manner as in Example 1, using CAT-2 instead of CAT-1. The physical properties of the obtained polymer are shown in Table 1 below.

[0155] Comparative Example 1

[0156] The polymerization reaction was carried out in the same manner as in Example 1, using Ph2C(Cp)(Flu)ZrCl2 (diphenylmethylene(cyclopentadienyl)(9-fluorenyl)zirconium dichloride) catalyst instead of CAT-1. The physical properties of the resulting polymer are shown in Table 1 below.

[0157] Comparative Example 2

[0158] The polymerization reaction was carried out in the same manner as in Example 1, using Et(IND)2ZrCl2 (ethylenebis(indenyl)zirconium dichloride) catalyst instead of CAT-1. The physical properties of the obtained polymer are shown in Table 1 below.

[0159] Comparative Example 3

[0160] The polymerization reaction was carried out in the same manner as in Example 1, using Et(THI)2ZrCl2 (ethylenebis(tetrahydroindenyl)zirconium dichloride) catalyst instead of CAT-1. The physical properties of the obtained polymer are shown in Table 1 below.

[0161] Comparative Example 4

[0162] The polymerization reaction was carried out in the same manner as in Example 1, except that catalyst CAT-1 (7.8 μmol) was used alone without CAT-3. The physical properties of the obtained polymer are shown in Table 1 below.

[0163] Comparative Example 5

[0164] The polymerization reaction was carried out in the same manner as in Example 1, except that catalyst CAT-2 (7.8 μmol) was used alone, without CAT-1 and CAT-3. The physical properties of the obtained polymer are shown in Table 1 below.

[0165] Comparative Example 6

[0166] The polymerization reaction was carried out in the same manner as in Example 1, except that the catalyst CAT-3 (7.8 μmol) was used alone without CAT-1. The physical properties of the obtained polymer are shown in Table 1 below.

[0167] [Table 1]

[0168]

[0169] As shown in Table 1, from the results of ethylene / 1-octene copolymerization in Examples 1 and 2, it can be seen that the polymers prepared using the novel catalyst system of the present invention, i.e., the combination of CAT-3 and CAT-1 (Example 1) and the combination of CAT-3 and CAT-2 (Example 2), have a molecular weight distribution of 4 or greater and a low density of 0.9 or less.

[0170] In Comparative Examples 4 to 6, CAT-1, CAT-2, and CAT-3 used alone, respectively, exhibited narrow molecular weight distributions. The combination of Ph2C(Cp)(Flu)ZrCl2 and CAT-3 (Comparative Example 1), the combination of Et(IND)2ZrCl2 and CAT-3 (Comparative Example 2), and the combination of Et(THI)2ZrCl2 and CAT-3 (Comparative Example 3) exhibited narrow molecular weight distributions and densities of 0.9 or higher.

[0171] Figure 1 The GPC data of Example 2 using CAT-3 and CAT-2 as polymerization catalysts are shown. As shown in Examples 1 and 2 of the present invention, when CAT-3 for preparing low molecular weight polymers is combined with CAT-1 and CAT-2 for preparing high molecular weight polymers as polymerization catalysts, it is found that bimodal polymers are prepared, such as Figure 1 shown.

[0172] That is, it was discovered that the novel catalyst system of the present invention is a catalyst system that can obtain a low-density polymer with a broad molecular weight distribution and a bimodal distribution under high-temperature and high-pressure polymerization conditions.

[0173] As described above, although the embodiments of the present invention have been described in detail, those skilled in the art may make various modifications to the present invention without departing from the scope of the present invention, as defined by the following statements. Therefore, any modifications to the following embodiments of the present invention do not depart from the technical solutions of the present invention.

Claims

1. A catalyst composition for preparing a vinyl polymer, comprising: A first transition metal compound as shown in Chemical Formula 1; A second transition metal compound as shown in Chemical Formula 2; and A co-catalyst selected from an aluminum compound, a boron compound or a mixture thereof: [Chemical Formula 1] [Chemical Formula 2] in M 1 It is a transition metal in Group 4 of the periodic table; R 1 to R 4 Each is independently a C1-C20 alkyl group or a C6-C20 aryl group; R 5 、R 6 、R 15 and R 16 are each independently a C6-C20 aryl group, and the R 5 、R 6 、R 15 and R 16 The aryl group in may be further substituted by a C1-C20 alkyl group; R 11 and R 12 Each is independently hydrogen or C1-C20 alkyl; X 1 、X 2 、X 11 and X 12 Each is independently halogen, C1-C20 alkyl, C3-C20 cycloalkyl, C6-C20 aryl, C6-C20 arylC1-C20 alkyl, (C1-C20 alkylC6-C20 aryl)C1-C20 alkyl, C1-C20 alkoxy, C6-C20 aryloxy, C1-C20 alkylC6-C20 aryloxy, C1-C20 alkoxyC6-C20 aryloxy, -OSiR a R b R c 、-SR d 、-NR e R f 、-PR g R h or C1-C20 alkylene; R a to R d Each is independently a C1-C20 alkyl group, a C6-C20 aryl group, a C6-C20 arylC1-C20 alkyl group, a C1-C20 alkylC6-C20 aryl group or a C3-C20 cycloalkyl group; R e to R h Each is independently a C1-C20 alkyl group, a C6-C20 aryl group, a C6-C20 arylC1-C20 alkyl group, a C1-C20 alkylC6-C20 aryl group or a C3-C20 cycloalkyl group; When X 1 and X 2 When one of is C1-C20 alkylene, the other is absent; and When X 11 and X 12 When one of the groups is a C1-C20 alkylene group, the other group is absent.

2. The catalyst composition for preparing vinyl polymers according to claim 1, Among them, M 1 is Zr or Hf; R 1 to R 4 Each is independently a C1-C20 alkyl group or a C6-C20 aryl group; R 5 、R 6 、R 15 and R 16 are each independently a C6-C20 aryl group, and the R 5 、R 6 、R 15 and R 16 The aryl group in may be further substituted by a C1-C20 alkyl group; R 11 and R 12 are each independently hydrogen or C1-C20 alkyl; and X 1 、X 2 、X 11 and X 12 Each is independently halogen, C1-C20 alkyl, C6-C20 aryl or C6-C20 arylC1-C20 alkyl.

3. The catalyst composition for preparing vinyl polymers according to claim 1, Among them, M 1 is Hf; R 1 to R 4 Each is independently a C1-C10 alkyl group or a C6-C12 aryl group; R 5 、R 6 、R 15 and R 16 are each independently a C6-C12 aryl group, and the R 5 、R 6 、R 15 and R 16 The aryl group in may be further substituted by a C1-C10 alkyl group; R 11 and R 12 are each independently hydrogen or C1-C10 alkyl; and X 1 、X 2 、X 11 and X 12 Each is independently halogen, C1-C10 alkyl, C6-C12 aryl or C6-C12 arylC1-C10 alkyl.

4. The catalyst composition for preparing vinyl polymers according to claim 1, Among them, M 1 is Hf; R 1 to R 4 Each is independently a C1-C10 alkyl group or a C6-C12 aryl group; R 5 、R 6 、R 15 and R 16 Each independently , wherein the R 21 is a C1-C10 alkyl group; a is an integer from 0 to 5; R 11 and R 12 are each independently hydrogen or C1-C10 alkyl; and X 1 、X 2 、X 11 and X 12 Each is independently halogen, C1-C6 alkyl, C6-C12 aryl or C6-C12 arylC1-C6 alkyl.

5. The catalyst composition for preparing vinyl polymers according to claim 1, in, The first transition metal compound is [1-(η5-cyclopentadien-1-yl)-1-(η5-2,7-dimethylaminofluorenyl)-1,1-diphenylmethane]dichlorohafnium, [1-(η5-cyclopentadien-1-yl)-1-(η5-2,7-dimethylaminofluorenyl)-1,1-diphenylmethane]dibenzylhafnium, or [1-(η5-cyclopentadien-1-yl)-1-(η5-2,7-dimethylaminofluorenyl)-1,1-diphenylmethane]dimethylhafnium; and The second transition metal compound is [1-(η5-cyclopentadien-1-yl)-1-(η5-fluorenyl)-1,1-diphenylmethane]dichlorohafnium, [1-(η5-cyclopentadien-1-yl)-1-(η5-fluorenyl)-1,1-diphenylmethane]dibenzylhafnium, [1-(η5-cyclopentadien-1-yl)-1-(η5-fluorenyl)-1,1-diphenylmethane]dimethylhafnium, [1-(η5-cyclopentadien-1-yl)-1-(η5-fluorenyl)-1,1-diphenylmethane]dimethylhafnium, [1-(η5 -cyclopentadien-1-yl)-1-(η5-2,7-di-tert-butylfluorenyl)-1,1-diphenylmethane]dichlorohafnium, [1-(η5-cyclopentadien-1-yl)-1-(η5-2,7-di-tert-butylfluorenyl)-1,1-diphenylmethane]dibenzyl, or [1-(η5-cyclopentadien-1-yl)-1-(η5-2,7-di-tert-butylfluorenyl)-1,1-diphenylmethane]dimethylhafnium.

6. The catalyst composition for preparing an ethylene-based polymer according to claim 1, wherein the aluminum compound is selected from one or more of aluminoxane compounds and organoaluminum compounds.

7. The catalyst composition for preparing an ethylene-based polymer as claimed in claim 1, wherein the aluminum compound is selected from one of methylaluminoxane, modified methylaluminoxane, tetraisobutylaluminoxane, trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum and trioctylaluminum, or a mixture thereof.

8. The catalyst composition for preparing vinyl polymers according to claim 1, wherein the boron compound is selected from the group consisting of dimethylphenylammonium tetraphenylborate, trityltetraphenylammonium borate, dimethylphenyltetrapentafluorophenylammonium borate, trityltetrakis(pentafluorophenyl)ammonium borate, trimethyltetraphenylammonium borate, triethyltetraphenylammonium borate, tripropyltetraphenylammonium borate, tributyltetraphenylammonium borate, trimethyltetrakis(pentafluorophenyl)ammonium borate, triethyltetrakis(pentafluorophenyl)ammonium borate, tripropyltetrakis(pentafluorophenyl)ammonium borate, tributyltetrakis(pentafluorophenyl)ammonium borate, tetraphenylborate aniline salt, tetrakis(pentafluorophenyl)borate aniline salt and tetrakis(pentafluorophenyl)borate pyridinium salt.

9. A method for preparing a vinyl polymer, comprising polymerizing a vinyl monomer in the presence of the catalyst composition for preparing a vinyl polymer according to any one of claims 1 to 8 to prepare a vinyl polymer.

10. The method for preparing an vinyl polymer according to claim 9, wherein the vinyl polymer is an ethylene homopolymer or a copolymer of ethylene and an α-olefin.

11. The method for preparing a vinyl polymer according to claim 10, wherein the vinyl monomer is ethylene or an α-olefin; and The α-olefin copolymerized with ethylene is selected from one or two or more of propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, cyclopentene, cyclohexene, norbornene, phenylnorbornene, 1,4-butadiene, 1,5-pentadiene, 1,6-hexadiene, styrene, α-methylstyrene, p-methylstyrene, divinylbenzene and 3-chloromethylstyrene.

12. The method for preparing an vinyl polymer according to claim 9, wherein the polymerization reaction is carried out at a temperature of 120 to 160°C and a pressure of 10 to 100 bar.

13. The method for preparing a vinyl polymer according to claim 9, wherein the polymerization reaction is carried out in a C5-C12 aliphatic hydrocarbon solvent.

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