Method for producing olefin polymer

Abstract

To provide a suitable method for efficiently producing an olefin polymer containing a relatively large number of polymer components having a high molecular weight such as a molecular weight of 106.5 or more, in which the high molecular weight polymer components preferably contain a relatively large number of structural units derived from an olefin having 3 or more carbon atoms.SOLUTION: There is provided a method for producing an olefin polymer by polymerizing an olefin in the presence of an olefin polymerization catalyst containing a solid titanium catalyst component in which the content of a substituent such as a well-known alkoxy group is in a specific range and an organometallic compound. The solid titanium catalyst component is preferably in a form of containing a silicon-containing compound.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a process for producing an olefin polymer containing ethylene. [Background technology]

[0002] Olefin polymers such as ethylene homopolymers and linear low-density ethylene polymers (LLDPE) are excellent in transparency and mechanical strength, and are widely used as raw materials for applications such as packaging materials and containers, such as films and bottles. Various methods have been disclosed for producing such ethylene polymers, and it is known that ethylene polymers can be produced with high polymerization activity by using an olefin polymerization catalyst containing a solid titanium catalyst component containing titanium, magnesium, a halogen, and an electron donor as an optional component (e.g., Patent Document 1). The particle properties of the solid titanium catalyst tend to have a significant effect on the stable operation and efficient production of the production process, and solid titanium catalyst components with excellent particle properties often contain a component such as an electron donor.

[0003] As mentioned above, olefin polymers are suitably used as raw materials for containers as alternative materials to glass, etc. Meanwhile, in recent years, due to growing awareness of environmental issues, there is a demand for further improving the durability of containers using olefin polymers, and there is a demand for olefin polymers that exhibit high performance in environmental stress resistance tests, etc. (e.g., Patent Document 2). In response to this trend, various standards such as PE100 and PE125 have been established. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-328514 [Patent Document 2] JP 2004-269864 A Summary of the Invention [Problem to be solved by the invention]

[0005] The olefin polymers having excellent durability as described above often contain components with extremely high molecular weights. In addition, appropriate toughness is also required. As such an olefin polymer, an ethylene copolymer containing a high molecular weight component containing a relatively large amount of olefin-derived structural units having 3 or more carbon atoms is considered to be suitable. On the other hand, olefins having 3 or more carbon atoms tend to have a significantly slower polymerization rate than ethylene, depending on the type of olefin polymerization catalyst, and it tends to be relatively difficult to produce the above-mentioned ethylene copolymers due to the relatively increased influence of chain transfer reactions, etc. In addition, since the molecular weight of an ethylene polymer is affected by the ratio between the polymerization rate of ethylene and the chain transfer rate, a relatively high polymerization rate of ethylene is also required to obtain a polymer with an extremely high molecular weight as described above. Therefore, an object of the present invention is to provide a method for producing an olefin polymer, which uses an olefin polymerization catalyst containing a solid titanium catalyst component, and which can easily produce an ethylene polymer containing a relatively large amount of structural units derived from an olefin having 3 or more carbon atoms even if the ethylene polymer has a high molecular weight. [Means for solving the problem]

[0006] As a result of investigations conducted by the present inventors to solve the above problems, they discovered that a method of polymerizing olefins in the presence of an olefin polymerization catalyst containing a solid titanium catalyst of a specific composition and an organometallic compound is preferable, and thus completed the present invention.

[0007] That is, the present invention is specified by the following requirements. <1> (A) Contains magnesium, titanium, and halogens as essential components; Magnesium: 10-25% by mass Titanium: 3-12% by mass The content of ORa groups is 0.5% by mass or more and less than 5% by mass, where Ra is a hydrocarbon group having 1 to 20 carbon atoms. a solid titanium catalyst component having a ratio of mass content of titanium to mass content of ORa groups of 1.5 to 20; (B) Organometallic compound A process for producing an olefin polymer, which comprises polymerizing an olefin in the presence of an olefin polymerization catalyst comprising: (PE1) The content of structural units derived from ethylene is 90 mol% or more and 99.5 mol% or less, (PE2) The content of structural units derived from olefins having 3 to 20 carbon atoms is 0.5 mol % or more and 10 mol % or less (provided that the total of PE1 and PE2 is 100 mol %). (D) Density is 900-960 kg / m 3 <2> The ORa group contains an ORb group (wherein Rb is a hydrocarbon group having 1 to 5 carbon atoms). <1> 2. The method for producing an olefin polymer according to claim 1 . <3> The content of the ORb group is 0.3 to 3 mass %. <2> 2. The method for producing an olefin polymer according to claim 1 . <4> The (A) solid titanium catalyst component is (a) a liquid magnesium compound; and (b) a liquid titanium compound, contacting the magnesium compound (a) in the presence of 0.25 to 0.35 moles of (c) an organosilicon compound having no active hydrogen, The resulting contact product (i) is heated to a temperature in the range of 105 to 115°C and maintained at this temperature to obtain a solid component, which is then contacted with (b) a liquid titanium compound to obtain a solid titanium catalyst component. <1> ~ <3> 2. The method for producing an olefin polymer according to claim 1 . Effect of the Invention

[0008] Using the above method, the molecular weight of 6.5 It is easy to produce a polymer containing a high molecular weight component exceeding 100%, and there is a tendency to easily obtain a polymer having a relatively large number of branched structures that are considered to be derived from olefins having 3 or more carbon atoms in the high molecular weight component. Therefore, it is possible to industrially produce olefin polymers having an appropriate branched structure in a wide molecular weight range. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 shows the GPC-IR results of Comparative Example 1 and Example 5. [Diagram 2] FIG. 2 shows the GPC-IR results of Comparative Example 2 and Example 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The solid titanium catalyst component, the olefin polymerization catalyst containing the same, and the olefin polymerization method according to the present invention will be described below. In the present invention, the term "polymerization" may be used to include not only homopolymerization but also copolymerization, and the term "polymer" may be used to include not only homopolymers but also copolymers. FIG. 1 is an explanatory diagram of the process for preparing a solid titanium catalyst component and an olefin polymerization catalyst containing the same according to the present invention.

[0011] <(A) Solid titanium catalyst component> The solid titanium catalyst component (A) of the present invention is Magnesium: 10-25% by mass Titanium: 3-12% by mass The content of ORa groups is 0.5% by mass or more and less than 5% by mass (wherein Ra is a hydrocarbon group having 1 to 20 carbon atoms). The ratio of the mass content of titanium to the mass content of the ORa group is 1.5 to 20. It satisfies the requirements.

[0012] The lower limit of the magnesium content is preferably 12 mass%, more preferably 13 mass%, and even more preferably 14 mass%, while the upper limit is preferably 23 mass%, more preferably 22 mass%, and even more preferably 21 mass%. The lower limit of the titanium content is preferably 4 mass%, more preferably 5 mass%, while the upper limit is preferably 11 mass%, more preferably 10 mass%, and even more preferably 9 mass%. The lower limit of the ORa group is preferably 0.6 mass%, more preferably 0.7 mass%, while the upper limit is preferably 4.5 mass%, more preferably 4.0 mass%, and even more preferably 3.5 mass%. Within the above range, olefins including ethylene can be polymerized with high activity to obtain high molecular weight olefin polymers, and the titanium catalyst component is suitable as a solid titanium catalyst component having excellent particle properties.

[0013] The above Ra is a substituent having 1 to 20 carbon atoms. It is preferably a hydrocarbon group consisting of carbon and hydrogen. A preferred example of such Ra is, for example, a structure corresponding to an alcohol used in combination with a magnesium compound described later. Among them, preferred specific examples include aliphatic hydrocarbons such as methyl group, ethyl group, propyl group, butyl group, hexyl group, octyl group, 2-ethylhexyl group, decyl group, undecyl group, tetradecyl group, hexadecyl group, octadecyl group, and eicosyl group; alicyclic hydrocarbon groups such as cyclopentyl group, cyclohexyl group, and cyclohexylmethyl group; and aromatic substituents such as phenyl group, tolyl group, and benzyl group. Among them, aliphatic hydrocarbon groups are preferred, more preferably hydrocarbon groups having 1 to 10 carbon atoms, and even more preferably ethyl group, butyl group, hexyl group, 2-ethylhexyl group, octyl group, and decyl group. In particular, an embodiment containing an ethyl group is preferred, and an embodiment in which a substituent (Rb) having 5 or less carbon atoms is combined with a substituent (Rc) having 6 to 10 carbon atoms, such as a combination of an ethyl group and a 2-ethylhexyl group, is preferred. In this case, the content of ORb groups is preferably 0.3% by mass or more and 3% by mass or less. A more preferred lower limit is 0.4% by mass, and even more preferred is 0.5% by mass. Meanwhile, a more preferred upper limit is 2.7% by mass, and even more preferred is 2.5% by mass.

[0014] The solid titanium catalyst component used in the present invention has a ratio of the mass content of titanium to the mass content of ORa groups of 1.5 to 20, with the lower limit being preferably 1.7, more preferably 2.0. The ratio of the mass content of titanium to the ORb group is preferably 3 to 40, with the lower limit being preferably 3.3, more preferably 3.5, and even more preferably 3.8. On the other hand, the upper limit is preferably 35, more preferably 30, and even more preferably 25. Such a range can generally be considered to be a low value for a catalyst particularly suitable for the polymerization of ethylene. An example of a method for preparing a solid titanium catalyst component that satisfies the above-mentioned requirements is a method in which the step (b) of contacting with a liquid titanium compound is carried out two or more times in the preparation method for a solid titanium catalyst component containing an alicyclic dicarboxylate disclosed in the above-mentioned Patent Document 1 or International Publication No. WO 09 / 125729. Here, the method for producing a solid titanium catalyst component of the present invention that utilizes the method for producing a solid titanium catalyst component disclosed in the above-mentioned Patent Document 1 is introduced as an example of a suitable production method. A suitable method for producing the above-mentioned solid titanium catalyst component according to the present invention is characterized by comprising a step of contacting (a) a liquid magnesium compound, (b) a liquid titanium compound, and a specific amount of (c) an organosilicon compound having no active hydrogen per mole of the magnesium compound (a) in the manner described below, to obtain a solid component, and then contacting the solid component with (b) a liquid titanium compound. The solid titanium catalyst component thus obtained contains magnesium, titanium, halogen, and (c) an organosilicon compound having no active hydrogen. First, each component used in preparing the solid titanium catalyst component of the present invention will be described below.

[0015] <(a) Liquid magnesium compound> In the present invention, when preparing the solid titanium catalyst component, the magnesium compound is used in a liquid state, and when the magnesium compound is in a solid state, it is liquefied before use. As the magnesium compound, a magnesium compound (a-1) having reducing ability and a magnesium compound (a-2) having no reducing ability can be used.

[0016] (a-1) As the magnesium compound having reducing ability, for example, there can be mentioned the organomagnesium compound represented by the following formula: X n MgR 2-n In the formula, n is 0≦n<2, R is a hydrogen atom or an alkyl group, an aryl group or a cycloalkyl group having 1 to 20 carbon atoms, and when n is 0, the two R's may be the same or different. X is a halogen.

[0017] Specific examples of such organic magnesium compounds having reducing ability include dialkyl magnesium compounds such as dimethyl magnesium, diethyl magnesium, dipropyl magnesium, dibutyl magnesium, diamyl magnesium, dihexyl magnesium, didecyl magnesium, octylbutyl magnesium, and ethylbutyl magnesium; alkyl magnesium halides such as ethyl magnesium chloride, propyl magnesium chloride, butyl magnesium chloride, hexyl magnesium chloride, and amyl magnesium chloride; alkyl magnesium alkoxides such as butyl ethoxy magnesium, ethyl butoxy magnesium, and octyl butoxy magnesium; and butyl magnesium hydride.

[0018] (a-2) Specific examples of magnesium compounds that do not have reducing ability include magnesium halides such as magnesium chloride, magnesium bromide, magnesium iodide, and magnesium fluoride; alkoxymagnesium halides such as methoxymagnesium chloride, ethoxymagnesium chloride, isopropoxymagnesium chloride, butoxymagnesium chloride, and octoxymagnesium chloride; aryloxymagnesium halides such as phenoxymagnesium chloride and methylphenoxymagnesium chloride; alkoxymagnesium such as ethoxymagnesium, isopropoxymagnesium, butoxymagnesium, n-octoxymagnesium, and 2-ethylhexoxymagnesium; aryloxymagnesium such as phenoxymagnesium and dimethylphenoxymagnesium; magnesium carboxylates such as magnesium laurate and magnesium stearate; magnesium metal; and magnesium hydride.

[0019] These magnesium compounds (a-2) without reducing ability may be compounds derived from the magnesium compounds (a-1) with reducing ability described above, or compounds derived during the preparation of the catalyst component. To derive the magnesium compounds (a-2) without reducing ability from the magnesium compounds (a-1) with reducing ability, for example, the magnesium compounds (a-1) with reducing ability may be contacted with alcohols, ketones, esters, ethers, siloxane compounds, halogen-containing silane compounds, halogen-containing aluminum compounds, acid halides, or other halogen-containing compounds, or compounds having OH groups or active carbon-oxygen bonds.

[0020] Furthermore, in the present invention, a compound (a-2) having no reducing ability can be derived from a magnesium compound (a-1) having reducing ability by using an organosilicon compound (c) having no active hydrogen, as described below. Two or more magnesium compounds can also be used in combination.

[0021] The magnesium compounds as described above may form complex compounds or composite compounds with metal compounds other than magnesium, such as aluminum, zinc, boron, beryllium, sodium, and potassium, for example, organoaluminum compounds described below, or may be used in combination with these other metal compounds.

[0022] When preparing the solid titanium catalyst component [I], magnesium compounds other than those mentioned above can be used. However, it is preferable that the magnesium compound is present in the form of a halogen-containing magnesium compound in the finally obtained solid titanium catalyst component [I]. Therefore, when a magnesium compound not containing a halogen is used, it is preferable to contact the magnesium compound with a halogen-containing compound during the preparation of the catalyst component.

[0023] Among the above compounds, magnesium compounds having no reducing ability are preferred, and halogen-containing magnesium compounds are particularly preferred, and among these, magnesium chloride, alkoxy magnesium chloride, and aryloxy magnesium chloride are preferably used.

[0024] In the present invention, when the magnesium compound is solid, it can be liquefied by using an electron donor (d-1). As the electron donor (d-1), alcohols, carboxylic acids, aldehydes, amines, metal acid esters, etc. can be used. Specific examples of the alcohols include aliphatic alcohols such as methanol, ethanol, propanol, isopropyl alcohol, butanol, pentanol, hexanol, 2-methylpentanol, 2-ethylbutanol, heptanol, 2-ethylhexanol, octanol, decanol, dodecanol, tetradecyl alcohol, octadecyl alcohol, undecenol, oleyl alcohol, stearyl alcohol, and ethylene glycol; alicyclic alcohols such as cyclohexanol and methylcyclohexanol; aromatic alcohols such as benzyl alcohol, methylbenzyl alcohol, isopropylbenzyl alcohol, α-methylbenzyl alcohol, α,α-dimethylbenzyl alcohol, phenylethyl alcohol, cumyl alcohol, phenol, cresol, xylenol, ethylphenol, propylphenol, nonylphenol, and naphthol; alkoxy group-containing alcohols such as n-butyl cellosolve, ethyl cellosolve, 1-butoxy-2-propanol, and methylcarbitol; and halogen-containing alcohols such as trichloromethanol, trichloroethanol, and trichlorohexanol.

[0025] The carboxylic acids are preferably those having 7 or more carbon atoms, such as caprylic acid, 2-ethylhexanoic acid, nonylic acid, undecylenic acid, etc. The acetaldehydes are preferably those having 7 or more carbon atoms, such as caprylaldehyde, 2-ethylhexylaldehyde, undecylaldehyde, benzaldehyde, tolualdehyde, naphthaldehyde, etc. The amines are preferably those having 6 or more carbon atoms, such as heptylamine, octylamine, 2-ethylhexylamine, nonylamine, decylamine, undecylamine, laurylamine, etc.

[0026] Examples of metal acid esters include tetraethoxytitanium, tetra-n-propoxytitanium, tetra-i-propoxytitanium, tetrabutoxytitanium, tetrahexoxytitanium, tetrabutoxyzirconium, and tetraethoxyzirconium. The metal acid esters do not include silicate esters as described below as (c) organic silicon compounds having no active hydrogen. These can be used in combination of two or more kinds, and can also be used in combination with an electron donor (d) other than the above as described below. Among these, alcohols and metal acid esters are preferred, and alcohols having 6 or more carbon atoms are particularly preferred.

[0027] When the electron donor (d-1) is used to liquefy a magnesium compound, it is usually used in an amount of about 1 mole or more, preferably 1 to 40 moles, more preferably 1.5 to 12 moles, per mole of the magnesium compound when an electron donor having 6 or more carbon atoms is used as the electron donor (d-1). When an electron donor having 5 or less carbon atoms is used, it is usually necessary to use about 15 moles or more per mole of the magnesium compound.

[0028] A hydrocarbon solvent can be used when the solid magnesium compound is brought into contact with the electron donor (d-1). Examples of such a hydrocarbon solvent include aliphatic hydrocarbons such as pentane, hexane, heptane, octane, decane, dodecane, tetradecane, and kerosene, alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, cyclooctane, and cyclohexene, aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene, and cymene, and halogenated hydrocarbons such as carbon tetrachloride, dichloroethane, dichloropropane, trichloroethylene, and chlorobenzene.

[0029] When aromatic hydrocarbons are used among these solvents, the electron donor (d-1), for example, alcohols, can dissolve the magnesium compound when used in the amount shown above for the electron donor having 6 or more carbon atoms, regardless of its type (number of carbon atoms). When aliphatic hydrocarbons and / or alicyclic hydrocarbons are used, the alcohols as the electron donor (d-1) are used in an amount according to the number of carbon atoms as described above.

[0030] In the present invention, it is preferable to contact the solid magnesium compound with the electron donor (d-1) in a hydrocarbon solvent. To dissolve the solid magnesium compound in the electron donor (d-1), the solid magnesium compound is generally contacted with the electron donor (d-1) preferably in the presence of a hydrocarbon solvent, and heated as necessary. This contact is usually performed at a temperature of 0 to 300°C, preferably 20 to 180°C, more preferably 50 to 150°C, for about 15 minutes to 5 hours, preferably about 30 minutes to 2 hours.

[0031] <(b) Liquid titanium compound> In the present invention, a tetravalent titanium compound is preferably used as the liquid titanium compound. Examples of such a tetravalent titanium compound include the compound represented by the following formula: Ti(OR) g X 4-g In the formula, R is a hydrocarbon group, X is a halogen atom, and 0≦g≦4.

[0032] Examples of such compounds include titanium tetrahalides such as TiCl4, TiBr4, and TiI4; trihalogenated alkoxytitaniums such as Ti(OCH3)Cl3, Ti(OC2H5)Cl3, Ti(On-C4H9)Cl3, Ti(OC2H5)Br3, and Ti(O-iso-C4H9)Br3; dihalogenated dialkoxytitaniums such as Ti(OCH3)2Cl2, Ti(OC2H5)2Cl2, Ti(On-C4H9)2Cl2, and Ti(OC2H5)2Br2; monohalogenated trialkoxytitaniums such as Ti(OCH3)3Cl, Ti(OC2H5)3Cl, Ti(On-C4H9)3Cl, and Ti(OC2H5)3Br; and tetraalkoxytitaniums such as Ti(OCH3)4, Ti(OC2H5)4, Ti(On-C4H9)4, Ti(O-iso-C4H9)4, and Ti(O-2-ethylhexyl)4. Among these, titanium tetrahalides are preferred, and titanium tetrachloride is particularly preferred. These titanium compounds can also be used in combinations of two or more. Further, they may be diluted with a hydrocarbon solvent as shown when liquefying the (a) magnesium compound and used.

[0033] <(c) Organosilicon compound having no active hydrogen> The organosilicon compound having no active hydrogen used in the present invention is, for example, R 1 xR 2 ySi(OR 3 )z (R 1 , R 2 are each independently a hydrocarbon group or a halogen, R 3 is a hydrocarbon group, and 0 ≦ x < 2, 0 ≦ y < 2, 0 < z ≦ 4. ).

[0034] Specific examples of the organosilicon compounds represented by such a formula include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetrakis(2-ethylhexyloxy)silane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, methyltrimethoxysilane, n-propyltriethoxysilane, decyltrimethoxysilane, cyclopentyltrimethoxysilane, 2-methylcyclopentyltrimethoxysilane, 2,3-dimethylcyclopentyltrimethoxysilane, cyclohexyltrimethoxysilane, 2-norbornanetrimethoxysilane, 2-norbornanemethyldimethoxysilane, phenyltrimethoxysilane, γ-chloropropyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, vinyl ... Ethoxysilane, t-butyltriethoxysilane, n-butyltriethoxysilane, iso-butyltriethoxysilane, decyltriethoxysilane, cyclopentyltriethoxysilane, cyclohexyltriethoxysilane, 2-norbornanetriethoxysilane, phenyltriethoxysilane, gamma-aminopropyltriethoxysilane, chlorotriethoxysilane, ethyltriisopropoxysilane, vinyltributoxysilane, trimethylphenoxysilane, methyltriallyloxy(allyloxy)silane, vinyltris(β-methoxyethoxysilane), vinyltriacetoxysilane, dimethyldimethoxysilane, diisopropyldimethoxysilane, t-butylmethyldimethoxysilane, dicyclopentyldimethoxysilane, bis(2-methylcyclopentyl)dimethoxysilane, bis(2,3-Dimethylcyclopentyl)dimethoxysilane, dicyclohexyldimethoxysilane, cyclohexylmethyldimethoxysilane, diphenyldimethoxysilane, phenylmethyldimethoxysilane, bis-o-tolyldimethoxysilane, bis-m-tolyldimethoxysilane, bis-p-tolyldimethoxysilane, bis-ethylphenyldimethoxysilane, dimethyldiethoxysilane, t-butylmethyldiethoxysilane, t-amylmethyldiethoxysilane, dicyclopentyldiethoxysilane, diphenyldiethoxysilane, bis-p-tolyldi Examples of the silane include ethoxysilane, cyclohexylmethyldiethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, tricyclopentylmethoxysilane, tricyclopentylethoxysilane, dicyclopentylmethylmethoxysilane, dicyclopentylethylmethoxysilane, hexenyltrimethoxysilane, cyclopentyldimethylmethoxysilane, cyclopentyldiethylmethoxysilane, dicyclopentylmethylethoxysilane, cyclopentyldimethylethoxysilane, and dimethyltetraethoxydisiloxane.

[0035] Of these, tetramethoxysilane, tetraethoxysilane, cyclohexylmethyldimethoxysilane, etc. are preferably used, with tetraethoxysilane being particularly preferred from the standpoint of catalytic activity.

[0036] In the above-mentioned embodiment, it is sufficient that the organosilicon compound (c) having no active hydrogen is contained in the finally obtained solid titanium catalyst component. Therefore, when preparing the solid titanium catalyst component, it is not necessary to use the organosilicon compound (c) having no active hydrogen as described above. In the process of preparing the solid titanium catalyst component, other compounds that can generate an organosilicon compound having no active hydrogen can also be used.

[0037] <(d) Other electron donors> In the present invention, when preparing the solid titanium catalyst component, it is preferable to use the above-mentioned organosilicon compound (c) having no active hydrogen, but it is also possible to use other electron donors (d) having no active hydrogen.

[0038] In the present invention, such other electron donors (d) include, for example, organic acid esters, organic acid halides, organic acid anhydrides, ethers, ketones, tertiary amines, phosphites, phosphates, carboxylic acid amides, nitriles, aliphatic carbonates, pyridines, etc. More specifically, methyl formate, methyl acetate, ethyl acetate, vinyl acetate, propyl acetate, i-butyl acetate, t-butyl acetate, octyl acetate, cyclohexyl acetate, methyl chloroacetate, ethyl dichloroacetate, ethyl propionate, ethyl pyruvate, ethyl pivalate, methyl butyrate, ethyl valerate, methyl methacrylate, ethyl crotonate, ethyl cyclohexanecarboxylate, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, octyl benzoate, cyclohexyl benzoate, etc. organic acid esters having 2 to 18 carbon atoms, such as xyl, phenyl benzoate, benzyl benzoate, methyl toluate, ethyl toluate, amyl toluate, ethyl ethylbenzoate, methyl anisate, ethyl anisate, and ethyl ethoxybenzoate; acid halides having 2 to 15 carbon atoms, such as acetyl chloride, benzoyl chloride, and toluic acid chloride; acid anhydrides, such as acetic anhydride, phthalic anhydride, maleic anhydride, benzoic anhydride, trimellitic anhydride, and tetrahydrophthalic anhydride; methyl ethers; Ethers with 2 to 20 carbon atoms, such as ethyl ether, isopropyl ether, butyl ether, amyl ether, tetrahydrofuran, ethyl benzyl ether, ethylene glycol dibutyl ether, anisole, and diphenyl ether; ketones with 3 to 20 carbon atoms, such as acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl n-butyl ketone, acetophenone, benzophenone, benzoquinone, and cyclohexanone; tertiary amines, such as trimethylamine, triethylamine, tributylamine, tribenzylamine, and tetramethylethylenediamine; phosphites, such as trimethyl phosphite, triethyl phosphite, tri-n-propyl phosphite, triisopropyl phosphite, tri-n-butyl phosphite, triisobutyl phosphite, diethyl n-butyl phosphite, and diethylphenyl phosphite; phosphates, such as trimethyl phosphate, triphenyl phosphate, and tritolyl phosphate; N,N-dimethylamide acetate, N,Examples of the compound include acid amides such as N-diethylamide and toluic acid N,N-dimethylamide, nitriles such as acetonitrile, benzonitrile, and tolunitrile, aliphatic carbonates such as dimethyl carbonate, diethyl carbonate, and ethylene carbonate, and pyridines such as pyridine, methylpyridine, ethylpyridine, and dimethylpyridine. Two or more of these compounds can also be used in combination.

[0039] <(A) Preparation of solid titanium catalyst component> The following is a specific method for preparing the solid titanium catalyst component (A) using the above-mentioned components in the present invention. (1) (a) a liquid magnesium compound is contacted with (b) a liquid titanium compound in the presence of (c) an organosilicon compound having no active hydrogen (hereinafter simply referred to as "organosilicon compound (c)") in an amount of 0.25 to 0.35 mol per mol of the magnesium compound (a), and the resulting contact product (i) is heated to a temperature within the range of 105 to 115°C and maintained at this temperature. (2) In the process of heating the contact product (i) and maintaining it at a temperature within the range of 105 to 115°C as described above, an organosilicon compound (c) is added in an amount of 0.5 mol or less per mol of the magnesium compound (a) and contacted with the contact product (i) during the period from a temperature 10°C lower than the maintaining temperature to the end of the temperature rise or after the end of the temperature rise. In the present invention, among the above methods, the method (2) may be preferable in terms of the catalytic activity of the resulting solid titanium catalyst component.

[0040] In the present invention, when each component is contacted, the organosilicon compound (c) is used in the amount specified above relative to the magnesium compound (a). The titanium compound (b) is preferably used in a sufficient amount to precipitate a solid product by contact without adding a special precipitation means. The amount of titanium compound (b) used varies depending on the type, contact conditions, amount of organosilicon compound (c) used, etc., but is usually preferably about 1 mole or more relative to 1 mole of magnesium compound (a), more preferably about 5 to about 200 moles, particularly preferably about 10 to about 100 moles. The titanium compound (b) is preferably used in an amount exceeding 1 mole relative to 1 mole of organosilicon compound (c), more preferably 5 moles or more.

[0041] Each of the above contact methods will be explained in more detail. The liquid magnesium compound (a) and / or titanium compound (b) used for contacting the liquid magnesium compound (a) with the titanium compound (b) may contain an organosilicon compound (c) in advance. In this case, it is not necessary to add the organosilicon compound (c) when the magnesium compound (a) and the titanium compound (b) are contacted, but it may be added. In either case, the total amount of the organosilicon compound (c) relative to the magnesium compound (a) should be within the above range.

[0042] In the present invention, the liquid magnesium compound (a) is preferably contacted with the liquid titanium compound (b) in the presence of the organosilicon compound (c) at a low temperature such that a solid is not rapidly formed by the contact, specifically, at a temperature of -70 to +50°C, preferably -50 to +30°C, and more preferably -40 to +20°C. The temperatures of the solutions used in the contact may be different. When the contact temperature is too low at the beginning of the contact and a solid is not precipitated in the contact product (i), the contact can be continued for a long time at a low temperature to precipitate a solid.

[0043] In the present invention, the contact product (i) obtained above is then gradually heated to a temperature within the range of 105 to 115°C to gradually precipitate a solid material, and this temperature is maintained. The holding time is usually about 0.5 to 6 hours, preferably about 1 to 4 hours. The time required for heating varies greatly depending on the scale of the reactor, etc.

[0044] When the liquid magnesium compound (a) is contacted with the liquid titanium compound (b) in the presence of an organosilicon compound (c) having no active hydrogen under such conditions, granular or spherical solid particles having a relatively large particle size and a good particle size distribution can be obtained. In the preferred method of the present invention, the solid particles are filtered off, and then the solid particles are contacted with the liquid titanium compound (b) for a second time to obtain a solid titanium catalyst component. The steps of filtering and contacting with the liquid titanium compound (b) can be repeated as long as they are within the scope of the object of the present invention. In the second or subsequent contact steps between the liquid titanium compound (b) and the solid component, the titanium content in the solid titanium catalyst component does not change much, but the content of the ORa group tends to decrease relatively easily. For this reason, this is an effective means for adjusting the ratio of titanium to the ORa group. The effect of the method of contacting with the liquid titanium compound (b) two or more times is not limited to the method described in Patent Document 1 as above. For example, the method can be applied to known methods for producing solid olefin polymerization catalysts, such as the method for producing a solid titanium catalyst component containing an alicyclic dicarboxylic acid ester disclosed in International Publication No. WO 09 / 125729. By polymerizing ethylene or an olefin having 3 or more carbon atoms by a method such as slurry polymerization using the solid titanium catalyst component thus obtained, which preferably has excellent particle properties, an ethylene polymer satisfying the requirements described below can be produced.

[0045] In the contact method (2), in the above-mentioned (1), the contact product (i) is heated to a temperature within the range of 105 to 115°C and maintained at this temperature for usually 0.5 to 6 hours, preferably 1 to 4 hours. During this process, an organosilicon compound (c) is added in an amount of 0.5 mol or less per mol of the magnesium compound (a) and contacted with the contact product (i) during the period from a temperature 10°C lower than the maintained temperature to the end of the temperature increase or after the end of the temperature increase (preferably immediately after).

[0046] The solid titanium catalyst component according to the present invention prepared as described above contains magnesium, titanium, halogen, and (c) an organosilicon compound having no active hydrogen. In this solid titanium catalyst component, the magnesium / titanium (atomic ratio) is about 2 to about 100, preferably about 4 to about 50, more preferably about 5 to about 30, the halogen / titanium (atomic ratio) is about 4 to about 100, preferably about 5 to about 90, more preferably about 8 to about 50, and the organosilicon compound (c) / titanium (molar ratio) is about 0.01 to about 100, preferably about 0.2 to about 10, more preferably about 0.4 to about 6. The organosilicon compound (c) / magnesium (molar ratio) is preferably about 0.001 to about 0.1, preferably about 0.002 to about 0.08, particularly preferably 0.005 to 0.05.

[0047] The solid titanium catalyst component may contain other components such as a carrier in addition to the above components, and specifically may contain other components in an amount of 50% by weight or less, preferably 40% by weight or less, more preferably 30% by weight or less, and further preferably 20% by weight or less. The composition of the catalyst component can be measured by ICP (atomic absorption spectrometry), gas chromatography, etc., after thoroughly washing the solid titanium catalyst component with a large amount of hexane and drying it under conditions of 0.1 to 1 Torr and room temperature for 2 hours or more.

[0048] The shape of the solid titanium catalyst component according to the present invention is preferably granular or nearly spherical, and its specific surface area is about 10 m 2 / g or more, preferably about 100 to 1000m 2In the present invention, the solid titanium catalyst component is usually used after washing with a hydrocarbon solvent.

[0049] <Olefin polymerization catalyst> The olefin polymerization catalyst according to the present invention is formed from the above-mentioned (A) solid titanium catalyst component and (B) an organometallic compound.

[0050] The organometallic compound (B) used in the present invention preferably contains a metal selected from Groups 1 and 2 to 13 of the periodic table. Specific examples of the organometallic compound include organoaluminum compounds, alkyl complex compounds of Group 1 metals and aluminum, and organometallic compounds of Group 2 metals.

[0051] As such an organoaluminum compound, for example, an organoaluminum compound represented by the following formula can be mentioned. R α n AIX 3-n (In the formula, R α is a hydrocarbon group having 1 to 12 carbon atoms, X is a halogen or hydrogen, and n is 1 to 3.

[0052] R αis a hydrocarbon group having 1 to 12 carbon atoms, such as an alkyl group, a cycloalkyl group, or an aryl group, and specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an isobutyl group, a pentyl group, a hexyl group, an octyl group, a cyclopentyl group, a cyclohexyl group, a phenyl group, and a tolyl group. Specific examples of such organoaluminum compounds include trialkylaluminums such as trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, trioctylaluminum, and tri-2-ethylhexylaluminum; alkenylaluminums such as isoprenylaluminum; dialkylaluminum halides such as dimethylaluminum chloride, diethylaluminum chloride, diisopropylaluminum chloride, diisobutylaluminum chloride, and dimethylaluminum bromide; alkylaluminum sesquihalides such as methylaluminum sesquichloride, ethylaluminum sesquichloride, isopropylaluminum sesquichloride, butylaluminum sesquichloride, and ethylaluminum sesquibromide; alkylaluminum dihalides such as methylaluminum dichloride, ethylaluminum dichloride, isopropylaluminum dichloride, and ethylaluminum dibromide; and alkylaluminum hydrides such as diethylaluminum hydride and diisobutylaluminum hydride.

[0053] As the organoaluminum compound, a compound represented by the following formula can also be used. R α n AlY 3-n In the above formula, R α is the same as above, and Y is -OR β Group, -OSiR c 3 groups, -OAlR d 2 units, -NR e 2 units, -SiR f 3 groups or -N(R g )AlR h 2 groups, n is 1 to 2, and R β , R c , Rd and R h is a methyl group, an ethyl group, an isopropyl group, an isobutyl group, a cyclohexyl group, a phenyl group, etc., and R e is hydrogen, methyl, ethyl, isopropyl, phenyl, trimethylsilyl, etc., and R f and R g is a methyl group, an ethyl group, etc.

[0054] As such an organoaluminum compound, specifically, the following compounds are used: (i)R α n Al(OR β ) 3-n Dimethylaluminum methoxide, diethylaluminum ethoxide, diisobutylaluminum methoxide, etc. (ii)R α n Al(OSiR c ) 3-n Et2Al(OSiMe3), (iso-Bu)2Al(OSiMe3), (iso-Bu)2Al(OSiEt3), etc. (iii)R α n Al(OAlR d 2) 3-n Et2AlOAlEt2, (iso-Bu)2AlOAl(iso-Bu)2, etc. (iv) R α n Al(NR e 2) 3-n Me2AlNEt2, Et2AlNHMe, Me2AlNHEt, Et2AlN(Me3Si)2, (iso-Bu)2AlN(Me3Si)2, etc. (v)R α n Al(SiR f 3) 3-n (iso-Bu)2AlSiMe3, etc. (vi)R α n Al〔N(Rg )-AlR h 2) 3-n Et2AlN(Me)-AlEt2 (iso-Bu)2AlN(Et)Al(iso-Bu)2 etc.

[0055] Also included are similar compounds, such as organoaluminum compounds in which two or more aluminum atoms are bonded via oxygen or nitrogen atoms. More specifically, examples include (C2H5)2AlOAl(C2H5)2, (C4H9)2AlOAl(C4H9)2, (C2H5)2AlN(C2H5)Al(C2H5)2, and aluminoxanes such as methylaluminoxane.

[0056] Examples of the alkyl complexes of Group 1 metals and aluminum include compounds represented by the following general formula: M 1 AlR j 4 (M 1 are Li, Na, and K, and R j is a hydrocarbon group having 1 to 15 carbon atoms. Specific examples of such compounds include LiAl(C2H5)4, LiAl(C7H 15 )4 etc.

[0057] Examples of the organometallic compound of a Group 2 metal include compounds represented by the following general formula: R k R l M 2 (R k , R l are a hydrocarbon group having 1 to 15 carbon atoms or a halogen, and may be the same or different, except for the case where both are halogen. 2 are Mg, Zn, and Cd.) Specific examples include diethyl zinc, diethyl magnesium, butylethyl magnesium, ethyl magnesium chloride, and butyl magnesium chloride.

[0058] Among the above organoaluminum compounds, R α 3AlX 3-n , R α n Al(OR β ) 3-n , R α n Al(OAlR d 2) 3-n The compounds represented by the formula (I) are preferably used, particularly trialkylaluminum. Two or more of these compounds can be used in combination. In the ethylene polymerization catalyst according to the present invention, olefins may be prepolymerized. The olefin polymerization catalyst according to the present invention may contain other components useful for the polymerization of ethylene, in addition to the above-mentioned components.

[0059] <Olefin Polymerization Method> In the ethylene polymerization method (main polymerization) according to the present invention, an olefin is polymerized in the presence of an ethylene polymerization catalyst comprising (A) a solid titanium catalyst component and (B) an organometallic compound as described above. Specifically, a preferred embodiment is one in which ethylene is copolymerized with an olefin having 3 or more carbon atoms.

[0060] Specific examples of the olefins having 3 or more carbon atoms include α-olefins having 3 to 20 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4,4-dimethyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene. Furthermore, vinyl compounds, other unsaturated compounds, polyene compounds, etc. can also be copolymerized, and examples of such copolymers include aromatic vinyl compounds such as styrene, substituted styrenes, allylbenzene, substituted allylbenzenes, vinylnaphthalenes, substituted vinylnaphthalenes, allylnaphthalenes, and substituted allylnaphthalenes; alicyclic vinyl compounds such as vinylcyclopentane, substituted vinylcyclopentanes, vinylcyclohexane, substituted vinylcyclohexanes, vinylcycloheptane, substituted vinylcycloheptanes, and allylnorbornane; Cyclic olefins such as cyclopentene, cycloheptene, norbornene, 5-methyl-2-norbornene, tetracyclododecene, and 2-methyl-1,4,5,8-dimethano-1,2,3,4,4a,5,8,8a-octahydronaphthalene, and silane-based unsaturated compounds such as allyltrimethylsilane, allyltriethylsilane, 4-trimethylsilyl-1-butene, 6-trimethylsilyl-1-hexene, 8-trimethylsilyl-1-octene, and 10-trimethylsilyl-1-decene can also be copolymerized.

[0061] Two or more of the above olefins having 3 or more carbon atoms can also be copolymerized with ethylene. In the present invention, in the polymerization of ethylene, the (A) solid titanium catalyst component (or prepolymerization catalyst) is preferably used in an amount of usually about 0.0001 to 1.0 millimole, calculated as titanium atom, per liter of polymerization volume. The (B) organometallic compound is preferably used in an amount such that the metal atom in the catalyst component is usually about 1 to 2000 moles, preferably about 5 to 500 moles, per mole of titanium atom in the (A) solid titanium catalyst component in the polymerization system.

[0062] The polymerization can be carried out by either a liquid phase polymerization method such as solution polymerization or suspension polymerization, or a gas phase polymerization method. When the polymerization is carried out in the form of a slurry polymerization reaction, an organic solvent that is usually inert to polymerization is used as the polymerization solvent. Specifically, the organic solvent can be an aliphatic hydrocarbon such as propane, butane, pentane, hexane, heptane, octane, decane, dodecane, or kerosene, an alicyclic hydrocarbon such as cyclopentane, cyclohexane, or methylcyclopentane, an aromatic hydrocarbon such as benzene, toluene, or xylene, or a halogenated hydrocarbon such as ethylene chloride or chlorobenzene. These may be used in combination. Also, a copolymerization monomer that is liquid at the reaction temperature can be used together with the organic solvent.

[0063] The polymerization conditions vary depending on the type of polymerization or the type of ethylene polymer to be obtained, but the polymerization is usually carried out at a temperature of about 20 to 300°C, preferably about 50 to 150°C, under normal pressure to 100 kg / cm. 2 Preferably about 2 to 50 kg / cm 2 This is carried out under pressure.

[0064] The molecular weight of the polymer obtained can be adjusted by using hydrogen during the polymerization. The above-mentioned polymerization can be carried out by any of batch, semi-continuous, and continuous methods. Furthermore, the polymerization can be carried out in two or more stages by changing the reaction conditions.

[0065] In the present invention, when olefins are polymerized, a catalyst is formed using the specific solid titanium catalyst component (A) described above, which allows the production of a specific olefin polymer as described below with extremely high polymerization activity. The resulting ethylene polymer has a low catalyst content, particularly a low halogen content, per polymer unit, and is less likely to cause mold rust during molding. In addition, the ethylene polymer has a low fine powder content and is excellent in particle properties, so it may be used without pelletizing.

[0066] (Olefin polymer) The olefin polymer obtained by the process for producing an olefin polymer of the present invention is characterized by satisfying the following requirements. (PE1) The content of structural units derived from ethylene is 90 mol% or more and 99.5 mol% or less, (PE2) The content of structural units derived from olefins having 3 to 20 carbon atoms is 0.5 mol % or more and 10 mol % or less (provided that the total of PE1 and PE2 is 100 mol %). (D) Density is 900-960 kg / m 3

[0067] The lower limit of the content of structural units derived from ethylene (PE1) is preferably 93 mass%, more preferably 95 mass%, and even more preferably 97 mass%, while the upper limit is preferably 99.0 mass%, more preferably 98.5 mass%, and even more preferably 98.0 mass%. The lower limit of the content of the structural unit derived from an olefin having 3 to 20 carbon atoms (PE2) is preferably 1.0 mass%, more preferably 1.5 mass%, and even more preferably 2.0 mass%, while the upper limit is preferably 7 mass%, more preferably 5 mass%, and even more preferably 3 mass%.

[0068] The content of the above olefin-derived structural units is 13Perform NMR measurement with a CNMR device, assign peaks at characteristic sites of the corresponding olefin by a conventional method, and determine them by area quantification. Alternatively, if IR measurement is performed on various olefin polymers with different compositions and a calibration curve is prepared, the content of structural units derived from olefins can also be determined by IR measurement. In the examples of the present invention, the content of the structural units derived from olefins is determined by the latter method using IR measurement.

[0069] (D) The preferable lower limit of the density of the olefin polymer of the present invention is 910 kg / m 3 and more preferably 920 kg / m 3 and even more preferably 930 kg / m 3 . On the other hand, the preferable upper limit is 955 kg / m 3 . Such an olefin polymer with such a density, or a so-called olefin polymer composition containing such an olefin polymer, is excellent in impact resistance, toughness, environmental resistance (for example, environmental stress cracking (ESCR) resistance), etc., and is suitable as a raw material polymer for packaging materials, containers, etc. The density of the olefin polymer of the present invention is determined using a density gradient tube in accordance with the method described in JIS K 6922 standard.

[0070] The olefin polymer to which the present invention pertains preferably has a content of components with a molecular weight of 10 6.5 or more determined by (H)GPC measurement of 2% by mass or more.

[0071] (H) The more preferable lower limit of the content of components with a molecular weight of 10 6.5 or more determined by GPC-IR measurement is 2.5% by mass, even more preferably 4% by mass, particularly preferably 5% by mass, and especially preferably 6% by mass. On the other hand, the upper limit is more preferably 30% by mass, even more preferably 25% by mass, particularly preferably 22% by mass, and especially preferably 20% by mass. The GPC-IR measurement conditions in the present invention are as follows.

[0072] <GPC-IR measurement> Apparatus: GPC-IR (registered trademark) type gel permeation chromatograph (Polymer Char) Detector (built-in): IR6 MCT infrared detector (Polymer Char) Detection wavelength: methylene sensor (2,920 cm -1 ), methyl sensor (2,960 cm -1 ) Columns: 2x TSKgel GMH6-HT + 2x TSKgel GMH6-HTL (7.5 mm ID x 30 cm, Tosoh) Column temperature: 150℃ Mobile phase: o-dichlorobenzene (ODCB) with BHT Flow rate: 1.0 mL / min Sample concentration: 10 mg / 20 mL (0.5 mg / mL) Melting conditions: 145 °C, 120 min Sample filtration: 1.0 μm sintered filter Injection volume: 0.4 mL Column calibration: Measurement is performed under conditions of monodisperse polystyrene (TSKgel standard polystyrene; Tosoh), and the obtained chromatogram is analyzed by a known method to obtain the above-mentioned content. Furthermore, by using an FT-IR device in combination as a detection device, information such as branching in each molecular weight component can be obtained.

[0073] By using the method for producing an olefin polymer of the present invention, 6.5 Even in the case of a high molecular weight polymer exceeding the range of 100%, a polymer having a relatively high content of structural units derived from olefins having 3 or more carbon atoms can be obtained. In addition, the variation (variation) in the content of structural units derived from olefins having 3 or more carbon atoms due to molecular weight is relatively small. This can be confirmed by the above-mentioned method of combining GPC and FT-IR. Molecular weight is 10 6.5It is known that high molecular weight components in the range exceeding this range have excellent resistance to deformation, such as "impact resistance," "toughness," and "environmental resistance (e.g., environmental stress rupture resistance (ESCR))." However, since olefins having 3 or more carbon atoms tend to have a slower reaction rate than ethylene, it appears that it has been difficult to obtain high molecular weight olefin polymer components in the range of molecular weights exceeding 1 million, which have a relatively high content of structural units derived from olefins having 3 or more carbon atoms, in the conventionally known methods for producing olefin polymers using olefin polymerization catalysts containing solid titanium catalyst components (see Comparative Examples described below). Olefin polymers containing olefin-derived structural units having 3 or more carbon atoms are considered to have a branched structure, and are polymers with a relatively low degree of crystallinity, which is expected to contribute to improving toughness. Therefore, the above-mentioned components having a high molecular weight and relatively many branches are preferred components that are expected to have multiple excellent properties such as impact resistance, toughness, and "environmental resistance (e.g., environmental stress rupture resistance (ESCR))". (Hereinafter, this may be referred to as component (HB).) However, since environmental resistance may decrease if there are too many branches, it is preferable that the variation in branching degree relative to molecular weight is as small as possible (narrow distribution). (For example, the relatively gentle curves showing the relationship between molecular weight and branching in the GPC-IR measurement charts in Figures 1 and 2 are examples that show the above-mentioned variation in branching degree is small.)

[0074] According to the investigations of the present inventors, by using an olefin polymerization catalyst containing a solid-state single catalyst component having a specific composition, when ethylene is polymerized, it is easy to obtain a polymer having a high molecular weight, and there is also a tendency that a polymer containing the above-mentioned component (HB) is easily obtained. Although the exact reason why an olefin polymer having such characteristics is obtained is unclear, the present inventors speculate as follows. The solid titanium catalyst component having a specific range of the content of the ORa group as described above is characterized in that the content of the ORa group relative to titanium is relatively low, but not zero. It is generally known that catalysts having a relatively large amount of the ORa group tend to have high polymerization activity, particularly for ethylene. On the other hand, a solid titanium catalyst component having a low content of the ORa group may have low polymerization activity, but may easily obtain a polymer with a high molecular weight. If the content of the ORa group of the present invention is within a specific range, it may be possible to obtain a polymer with a high molecular weight while maintaining high polymerization activity for ethylene. In addition, in a solid titanium catalyst component containing a large amount of ORa groups, the presence of too many ORa groups tends to promote the reduction of titanium by the organometallic compound (B), and divalent titanium is easily produced over time, making it difficult to copolymerize olefins having 3 or more carbon atoms, and the effect becomes more pronounced at a molecular weight of 10. 6.5 This is believed to be the reason why the content of structural units derived from olefins having 3 or more carbon atoms tends to be low in high molecular weight substances in the range exceeding 10. If the content of the ORa group in the solid titanium catalyst component of the present invention is within the range, the promotion of reduction of titanium as described above can probably be relatively suppressed. 6.5 It can be considered that it is easy to obtain a polymer having a relatively high content of structural units derived from olefins having 3 or more carbon atoms in a high molecular weight range exceeding this range. It is also possible that in the second or subsequent contact steps with the liquid titanium compound as described above, Ti structures with an excess of ORa groups, such as Ti(ORa)3Cl, may be converted to structures such as Ti(ORa)2Cl2 or Ti(ORa)Cl3. As mentioned above, the solid titanium catalyst component of the present invention is an embodiment in which the valence of titanium, which is the active site, is relatively unlikely to change, and therefore it is believed that the polymerization reaction between ethylene and an olefin having 3 or more carbon atoms proceeds stably, making it easier to obtain a polymer having a high content of structural units derived from an olefin having 3 or more carbon atoms, which is an extremely high molecular weight component as described above. In addition, the reduction of titanium, which can form the active site, is suppressed, and the presence of titanium with a relatively stable valence is believed to also suppress variation in the degree of branching.

[0075] Other preferable physical properties of the olefin polymer obtained in the present invention include the following. The bulk density is desirably 0.20 to 0.60 g / cc, preferably 0.25 to 0.60 g / cc. The melt flow rate MFR (based on ASTM D1238E, 190° C.) is desirably 0.01 to 100 g / 10 min. The intrinsic viscosity [η] measured in decalin at 135° C. (based on JIS K 7367-3) is preferably 1.5 to 10 dl / g, more preferably 2.0 to 8 dl / g. The ethylene polymer obtained by the present invention as described above may also be blended with a heat stabilizer, a weather stabilizer, an antistatic agent, an antiblocking agent, a lubricant, a nucleating agent, a pigment, a dye, an inorganic or organic filler, etc., if necessary. Within the above range, the polymer can be suitably used as a raw material for films, containers, etc. In particular, it is suitable as a raw material for containers obtained by blow molding, etc. EXAMPLES

[0076] The present invention will now be described in detail with reference to examples, but is not limited to these examples. In the following examples, the composition, particle size and bulk density of the solid titanium catalyst component were measured as follows. (1)Mg, Ti content: The determination was made by the usual method using an ICP analyzer (Shimadzu Corporation, ICPF 1000TR). (2)Cl content: It was determined by silver nitrate titration. (3) OR group content: The thoroughly dried catalyst was added to an acetone solution containing 10% by mass of water, and the ROH obtained by hydrolysis was quantified by a conventional method using gas chromatography. (4) Particle size distribution: Measurements were performed in the usual manner using a vibrator (Iida Manufacturing, Rotap) and a device consisting of multiple stacks of sieves with different mesh sizes (Bunsei Furui, inner diameter 200 mm). (5) Bulk density: Measured according to JIS K-6721. (6) Density: The samples were prepared in accordance with JIS K6922 and measured using a density gradient tube. (7) Butene content: The comonomer content of the copolymer was measured by FT-IR (FT-IR4100 infrared spectrophotometer manufactured by JASCO Corporation). FT-IR was performed using a film obtained by melt-stretching the copolymer-generating polymer obtained in the examples in a hot press heated to 180°C and then cooling the film under pressure at room temperature as a measurement sample. -1 ~400cm -1 The butene content was measured by the C-CH2CH3 skeletal vibration (1378 cm -1 ) was used as the key band, and the absorbance of the key band (D1378) and the internal standard band (4321 cm -1 The absorbance was calculated from the ratio of the absorbance (D4321) of the CH stretching vibration and the methylene and methyl bending vibration (D1378 / D4321). On the other hand, the butene-derived structural unit content 13 For several types of ethylene / butene copolymers whose properties were identified by methods such as C NMR, the [D1378 / D4321] values ​​were obtained by the above method, and a calibration curve for the relationship between the [D1378 / D4321] value and the butene content was created based on the [D1378 / D4321] values. The content of butene-derived structural units was determined from this calibration curve and the measured values ​​of [D1378 / D4321] using the polymers of the Examples and Comparative Examples.

[0077] [Comparative Example 1] "Preparation of solid titanium catalyst component (A)" The solid titanium catalyst component (A) was prepared in the same manner as in Example 1 of JP-A-9-325814. The composition of the obtained solid titanium catalyst component (A) is shown in Table 1.

[0078] "polymerization" In a 1-liter autoclave, 500 ml of purified n-heptane was charged under a nitrogen atmosphere, and 0.78 mmol of triethylaluminum and the decane suspension of the solid titanium catalyst component (A) obtained above were added in an amount equivalent to 0.03 mmol of titanium atom. The temperature was then raised to 72°C, and hydrogen diluted with nitrogen to a hydrogen concentration of 5 mol% was fed at 0.01 MPa, followed by continuous feeding of an ethylene-butene mixed gas with a butene concentration of 2 mol% to a total pressure of 0.10 MPaG. The polymerization temperature was maintained at 72°C. After the polymerization was completed, the ethylene polymer was separated from the n-heptane solvent and dried. After drying, 28.3 g of a powdery polymer was obtained. The intrinsic viscosity [η] of this powdery polymer was 5.2 dl / g and the density was 932 kg / m 3 The butene content was 7.5 / 1000C, and the apparent bulk density was 0.30g / cc. The results are shown in Table 2. The results calculated by GPC-IR analysis are shown in Table 2. The GPC-IR measurement results are shown in Figure 1.

[0079] [Example 1] "Preparation of solid titanium catalyst component (B)" In a reactor under nitrogen, 4.57 g of the solid titanium catalyst component (A) was charged, followed by 110 ml of titanium tetrachloride, and the temperature was set to 20°C. The temperature was then raised to 30°C over 10 minutes and maintained at that temperature for 35 minutes. After the 35-minute reaction was completed, the solid portion was separated by hot filtration, and this solid portion was thoroughly washed with 90°C decane and hexane until no free titanium compounds were detected in the washings, and a hexane suspension of the solid titanium catalyst component was obtained. The composition of the obtained solid titanium catalyst component (B) is shown in Table 1.

[0080] "polymerization" Polymerization was carried out in the same manner as in Comparative Example 1, except that the solid titanium catalyst component (A) was replaced with the solid titanium catalyst component (B). The results are shown in Table 2.

[0081] [Example 2] "Preparation of solid titanium catalyst component (C)" 4.66 g of the solid titanium catalyst component (A) and 112 ml of titanium tetrachloride were charged, and the temperature was set to 20° C. Then, the temperature was raised to 50° C. over 30 minutes, and the temperature was maintained for 35 minutes. Subsequent filtration and washing operations were carried out in the same manner as in Example 1. The composition of the obtained solid titanium catalyst component (C) is shown in Table 1.

[0082] "polymerization" Polymerization was carried out in the same manner as in Comparative Example 1, except that the solid titanium catalyst component (A) was replaced with the solid titanium catalyst component (C). The results are shown in Table 2.

[0083] [Example 3] "Preparation of solid titanium catalyst component (D)" 5.42 g of the solid titanium catalyst component (A) and 130 ml of titanium tetrachloride were charged, and the temperature was set to 20° C. Then, the temperature was raised to 70° C. over 50 minutes, and the temperature was maintained for 35 minutes. Subsequent filtration and washing operations were carried out in the same manner as in Example 1. The composition of the obtained solid titanium catalyst component (D) is shown in Table 1.

[0084] "polymerization" Polymerization was carried out in the same manner as in Comparative Example 1, except that the solid titanium catalyst component (A) was replaced with the solid titanium catalyst component (D). The results are shown in Table 2.

[0085] [Example 4] "Preparation of solid titanium catalyst component (E)" 4.88 g of the solid titanium catalyst component (A) and 117 ml of titanium tetrachloride were charged, and the temperature was set to 20° C. Then, the temperature was raised to 90° C. over 70 minutes, and the temperature was maintained for 35 minutes. Subsequent filtration and washing operations were carried out in the same manner as in Example 1. The composition of the obtained solid titanium catalyst component (E) is shown in Table 1.

[0086] "polymerization" Polymerization was carried out in the same manner as in Comparative Example 1, except that the solid titanium catalyst component (A) was replaced with the solid titanium catalyst component (E). The results are shown in Table 2.

[0087] [Example 5] "Preparation of solid titanium catalyst component (F)" 4.60 g of the solid titanium catalyst component (A) and 110 ml of titanium tetrachloride were charged, and the temperature was set to 20° C. Then, the temperature was raised to 110° C. over 90 minutes, and the temperature was maintained for 35 minutes. Subsequent filtration and washing operations were carried out in the same manner as in Example 1. The composition of the obtained solid titanium catalyst component (F) is shown in Table 1. The results of its GPC-IR measurement are shown in FIG. 1 and FIG. 2.

[0088] "polymerization" Polymerization was carried out in the same manner as in Comparative Example 1, except that the solid titanium catalyst component (A) was replaced with the solid titanium catalyst component (F). The results are shown in Table 2.

[0089] [Comparative Example 2] "Preparation of solid titanium catalyst component (G)" A solid titanium catalyst component was prepared in the same manner as in Example 1 of JP-A-58-83006. (Solid titanium catalyst component (G))

[0090] "polymerization" Polymerization was carried out in the same manner as in Comparative Example 1, except that the solid titanium catalyst component (A) was replaced with the solid titanium catalyst component (G). The results are shown in Table 2. The results of GPC-IR measurement are shown in FIG.

[0091] [Table 1]

[0092] [Table 2]

Claims

1. (A) containing magnesium, titanium, and a halogen as essential components; Magnesium: 10 to 25 mass% Titanium: 3 to 12 mass% The content of ORa groups is 0.5% by mass or more and less than 5% by mass, where Ra is a hydrocarbon group having 1 to 20 carbon atoms. a solid titanium catalyst component having a ratio of mass content of titanium to mass content of ORa groups of 1.5 to 20; (B) Organometallic compound and (D) a process for producing an olefin polymer, the process comprising: polymerizing an olefin in the presence of an olefin polymerization catalyst comprising: (PE1) the content of structural units derived from ethylene is 90 mol% or more and 99.5 mol% or less; (PE2) The content of structural units derived from olefins having 3 to 20 carbon atoms is 0.5 mol% or more and 10 mol% or less (provided that the total of PE1 and PE2 is 100 mol%). (D) Density is 900 to 960 kg / m 3

2. 2. The process for producing an olefin polymer according to claim 1, wherein the ORa group contains an ORb group, where Rb is a hydrocarbon group having 1 to 5 carbon atoms.

3. The method for producing an olefin polymer according to claim 2, wherein the content of the ORb group is 0.3 to 3 mass %.

4. The solid titanium catalyst component (A) is (a) a liquid magnesium compound; and (b) a liquid titanium compound, contacting the magnesium compound (a) in the presence of an organosilicon compound (c) having no active hydrogen in an amount of 0.25 to 0.35 moles per mole of the magnesium compound (a); The process for producing an olefin polymer according to claim 1, wherein the contact product (i) is heated to a temperature within a range of 105 to 115°C and maintained at this temperature to obtain a solid component, which is further contacted with (b) a liquid titanium compound to obtain a solid titanium catalyst component.

Images