JP2024146120A - Method for producing olefin polymer - Google Patents

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 (A) and an organoaluminum compound (B) having a substituent having a molecular weight of 30 or more. The solid titanium catalyst component (A) is preferably in a form of containing a silicon-containing compound.SELECTED DRAWING: None

Description

The present invention relates to a method for producing an olefin polymer containing ethylene.

Olefin polymers such as ethylene homopolymers and linear low density ethylene polymers (LLDPE) are excellent in transparency, mechanical strength, etc., 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.

As mentioned above, olefin polymers are suitable for use as a raw material for containers, as an alternative to glass and the like. On the other hand, 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 and the like (for example, Patent Document 2). In response to this trend, various standards such as PE100 and PE125 have been established.

Japanese Patent Application Publication No. 9-328514 JP 2004-269864 A

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 structural units derived from an olefin 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, although this depends on the type of olefin polymerization catalyst, and the influence of chain transfer reactions is relatively increased, making it relatively difficult to produce such ethylene copolymers.

Therefore, the objective of the present invention is to provide a method for producing an olefin polymer that uses an olefin polymerization catalyst that uses a solid titanium catalyst component, and that can easily produce an ethylene polymer that contains a relatively large amount of olefin-derived structural units having 3 or more carbon atoms, even if the ethylene polymer has a high molecular weight.

As a result of the inventor's investigations to solve the above problems, he discovered that a suitable method is to polymerize olefins in the presence of an olefin polymerization catalyst that contains a solid titanium catalyst containing specific components and an organoaluminum compound containing a substituent that satisfies specific requirements, and thus completed the present invention.

That is, the present invention is specified by the following requirements.
[1]
(A) containing magnesium, titanium, and a halogen;
10 to 25% by mass of magnesium,
Titanium: 2 to 12 mass%;
1 to 12% by mass of ORa groups (wherein Ra is a hydrocarbon group having 1 to 20 carbon atoms); and
(α) 0 to 12% by mass of a compound selected from a silicon-containing compound, an organic acid compound, an organic acid ester compound, a ketone compound, an aldehyde compound, a nitrogen-containing compound, and a phosphorus-containing compound
A solid titanium catalyst component comprising:
(B) An organoaluminum compound represented by the following formula (1) and R ₃ Al (1)
(wherein R is a substituent containing carbon, hydrogen, or a heteroatom, at least one of which has a molecular weight of 30 or more.)
A method 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 99.8 mol% or less;
(PE2) the content of structural units derived from olefins having 3 to 20 carbon atoms is 0.2 mol % or more and 10 mol % or less (provided that the total of the structural units derived from ethylene and the structural units derived from olefins having 3 to 20 carbon atoms is 100 mol %);
(D) density of 900 to 960 kg/m ³ ;
(H) The content of components having a molecular weight of 10 ^6.5 or more as determined by GPC measurement is 1.5 mass % or more.

[2]
The method for producing an olefin polymer according to [1], wherein at least one of R in the formula (1) has a molecular weight of 35 or more and 300 or less.

[3]
The method for producing an olefin polymer according to [1] or [2], wherein at least one of R in the formula (1) is a hydrocarbon group consisting of carbon atoms and hydrogen atoms.

[4]
2. The process for producing an olefin polymer according to claim 1, wherein the (A) solid titanium catalyst component is a solid titanium catalyst component obtained by contacting (a) a liquid magnesium compound with (b) a liquid titanium compound in the presence of (c) an organosilicon compound having no active hydrogen in an amount of 0.25 to 0.35 mol per 1 mol of the magnesium compound (a), and heating the resulting contact product (i) to a temperature within the range of 105 to 115°C and maintaining it at this temperature.

By using the above-mentioned method, it is easy to produce a polymer containing a high molecular weight component having a molecular weight exceeding 10 ^6.5 , and it is also easy to 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. Preferably, the branched structure content also tends to be less dependent on the molecular weight. Therefore, it is possible to industrially produce an olefin polymer having an appropriate branched structure in a wide molecular weight range.

FIG. 1 is a GPC-IR measurement chart of Example 1 and Comparative Example 1.

The solid titanium catalyst component according to the present invention, the ethylene polymerization catalyst containing the same, and the ethylene polymerization method 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 homopolymer but also copolymer.

<(A) Solid Titanium Catalyst Component>
The solid titanium catalyst component (A) of the present invention is
Contains magnesium, titanium, and halogens;
10 to 25% by mass of magnesium,
Titanium: 2 to 12 mass%;
1 to 12 mass % of ORa groups (wherein Ra is a hydrocarbon group having 1 to 20 carbon atoms), and (α) 0 to 12 mass % of a compound selected from a silicon-containing compound, an organic acid compound, an organic acid ester compound, a ketone compound, an aldehyde compound, a nitrogen-containing compound, and a phosphorus-containing compound.
Contains:

Such a solid titanium catalyst component can be selected from known solid titanium catalyst components. For example, in addition to the above-mentioned Patent Document 1, a solid titanium catalyst component containing an alicyclic dicarboxylic acid ester disclosed in International Publication No. 2009/125729 can be mentioned.

The lower limit of the magnesium content is preferably 11 mass%, more preferably 12 mass%, and even more preferably 13 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 3 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 1.2% by mass, more preferably 2% by mass, while the upper limit is preferably 11% by mass, more preferably 10% by mass, and even more preferably 9% by 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.

The 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 a Ra substituent is, for example, a structure corresponding to the alcohol used in combination with the magnesium compound described below. Among them, preferred specific examples include aliphatic hydrocarbons such as methyl, ethyl, propyl, butyl, hexyl, octyl, 2-ethylhexyl, decyl, undecyl, tetradecyl, hexadecyl, octadecyl, and eicosyl groups; alicyclic hydrocarbon groups such as cyclopentyl, cyclohexyl, and cyclohexylmethyl groups; and aromatic substituents such as phenyl, tolyl, and benzyl groups. Among these, aliphatic hydrocarbon groups are preferred, more preferably hydrocarbon groups having 1 to 10 carbon atoms, and even more preferably ethyl, butyl, hexyl, 2-ethylhexyl, octyl, and decyl groups. In particular, embodiments that include an ethyl group are preferred, and embodiments that combine a substituent with 5 or fewer carbon atoms, such as a combination of an ethyl group and a 2-ethylhexyl group, with a substituent with 6 to 10 carbon atoms are preferred.

The content of the alkoxy group (ORa ^L ) having 5 or less carbon atoms is preferably 0.5 to 5% by mass.
Such a substituent may be introduced into the solid titanium catalyst component, for example, from the alcohol compound used in the preparation of the liquid magnesium compound described below.

(α) Compounds such as silicon-containing compounds The solid titanium catalyst component used in the present invention is characterized by containing 0 to 12 mass% of a compound selected from silicon-containing compounds, organic acid compounds, organic acid ester compounds, ketone compounds, aldehyde compounds, nitrogen-containing compounds, and phosphorus-containing compounds. The preferred lower limit is 0.2 mass%, and the preferred upper limit is 10 mass%, more preferably 9 mass%, and even more preferably 8 mass%. Examples of such compounds include (c) organic silicon compounds that do not have active hydrogen, which will be introduced as examples of solid titanium catalyst components later, and (d) components derived from other electron donors.

Among the solid titanium catalyst components that satisfy the above requirements, the solid titanium catalyst component disclosed in the above-mentioned Patent Document 1 is preferred in the present invention. Preferred examples are introduced below.

The solid titanium catalyst component (A) according to the present invention is obtained by 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 mol of the magnesium compound (a) in a manner described below, and contains magnesium, titanium, a halogen, and (c) an organosilicon compound having no active hydrogen.
First, each component used in preparing the solid titanium catalyst component (A) of the present invention will be described below.

(a) Liquid magnesium compound In the present invention, the magnesium compound is used in a liquid state when preparing the solid titanium catalyst component, 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.

(a-1) As the magnesium compound having reducing ability, for example, there can be mentioned the organomagnesium compound represented by the following formula:
_{XnMgR2 -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.)

Specific examples of organic magnesium compounds having such 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.

(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; alkoxy magnesium halides such as methoxy magnesium chloride, ethoxy magnesium chloride, isopropoxy magnesium chloride, butoxy magnesium chloride, and octoxy magnesium chloride; aryloxy magnesium halides such as phenoxy magnesium chloride and methylphenoxy magnesium chloride; alkoxy magnesium such as ethoxy magnesium, isopropoxy magnesium, butoxy magnesium, n-octoxy magnesium, and 2-ethylhexoxy magnesium; aryloxy magnesium such as phenoxy magnesium and dimethylphenoxy magnesium; magnesium carboxylates such as magnesium laurate and magnesium stearate; magnesium metal; and magnesium hydride.

These magnesium compounds (a-2) that do not have reducing ability may be compounds derived from the magnesium compounds (a-1) that have reducing ability described above, or compounds derived during the preparation of the catalyst component. To derive the magnesium compounds (a-2) that do not have reducing ability from the magnesium compounds (a-1) that have reducing ability, for example, the magnesium compounds (a-1) that have 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 with compounds that have OH groups or active carbon-oxygen bonds.

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.

The magnesium compounds described above may form complexes or complexes 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.

When preparing the solid titanium catalyst component (A), magnesium compounds other than those mentioned above can be used, but it is preferable that they are present in the form of a halogen-containing magnesium compound in the solid titanium catalyst component (A) finally obtained. Therefore, when using a magnesium compound that does not contain halogen, it is preferable to contact the magnesium compound with a halogen-containing compound during the catalyst component preparation process.

Among the above compounds, magnesium compounds that do not have 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.

In the present invention, when the magnesium compound as described above is solid, the magnesium compound can be liquefied using an electron donor (d-1). As such an electron donor (d-1), alcohols, carboxylic acids, aldehydes, amines, metal acid esters, etc. can be used. Specific examples of 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; benzyl alcohol, methylbenzyl alcohol, and the like. aromatic alcohols such as ethanol, 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-butylcellosolve, ethylcellosolve, 1-butoxy-2-propanol, and methylcarbitol; and halogen-containing alcohols such as trichloromethanol, trichloroethanol, and trichlorohexanol.

As the carboxylic acids, carboxylic acids having 7 or more carbon atoms are preferred, such as caprylic acid, 2-ethylhexanoic acid, nonylic acid, and undecylenic acid. As the acetaldehydes, acetaldehyde having 7 or more carbon atoms is preferred, such as caprylaldehyde, 2-ethylhexylaldehyde, undecylaldehyde, benzaldehyde, tolualdehyde, and naphthaldehyde. As the amines, amines having 6 or more carbon atoms are preferred, such as heptylamine, octylamine, 2-ethylhexylamine, nonylamine, decylamine, undecylamine, and laurylamine.

Metal acid esters include tetraethoxytitanium, tetra-n-propoxytitanium, tetra-i-propoxytitanium, tetrabutoxytitanium, tetrahexoxytitanium, tetrabutoxyzirconium, and tetraethoxyzirconium. Note that these metal acid esters do not include silicate esters such as those described below as (c) organosilicon compounds that do not have active hydrogen. Two or more of these can be used in combination, and electron donors (d) other than those described below can also be used in combination. Of these, alcohols and metal acid esters are preferred, and alcohols having 6 or more carbon atoms are particularly preferred.

When liquefying a magnesium compound using the above electron donor (d-1), if an electron donor with 6 or more carbon atoms is used as the electron donor (d-1), it is usually used in an amount of about 1 mole or more, preferably 1 to 40 moles, and more preferably 1.5 to 12 moles, per mole of magnesium compound. If an electron donor with 5 or less carbon atoms is used, it is usually necessary to use about 15 moles or more per mole of magnesium compound.

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.

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.

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), a method is generally used in which the solid magnesium compound is contacted with the electron donor (d-1), preferably in the presence of a hydrocarbon solvent, and heated as necessary. This contact is usually carried out at a temperature of 0 to 300°C, preferably 20 to 180°C, more preferably 50 to 150°C, for about 15 minutes to 20 hours, preferably about 30 minutes to 10 hours.

(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.)

Specific examples of such compounds include titanium tetrahalides such as _TiCl4 , _TiBr4 , and _TiI4 ; alkoxy titanium trihalides such as Ti( _OCH3 ) _Cl3 , Ti( _OC2H5 ) _Cl3 , Ti( _On - _C4H9 ) _Cl3 , Ti( _OC2H5 ) _Br3 , and Ti( _O -iso- _C4H9 ) _Br3 ; dialkoxy titanium dihalides such as _Ti ( _{OCH3 ) 2Cl2 ,} Ti _{( OC2H5 ) 2Cl2 ,} Ti(On- _{C4H9 ) 2Cl2} , and Ti( _OC2H5 ) _{2Br2 ;} and Ti( _OCH3 ) _{3 . Examples} of the titanium compounds include monohalogenated trialkoxy titanium compounds such as Ti( _{OC2H5 ) 3Cl} , Ti(On- _C4H9 ) _3Cl , and Ti( _OC2H5 ) _3Br , and tetraalkoxy titanium compounds such as Ti( _OCH3 ) ₄ , Ti( _OC2H5 ) ₄ , Ti(On- _C4H9 ) ₄ , Ti( _O - _iso - _C4H9 ) ₄ , and _Ti (O _- 2-ethylhexyl). Among these, titanium tetrahalides are preferred, and titanium tetrachloride is particularly preferred. These titanium compounds can be used in combination of _two or more kinds. The titanium compounds can also be used by diluting them in a hydrocarbon solvent as described in (a) for liquefying the magnesium compound.

(c) Organosilicon Compounds Having No Active Hydrogen The ^{organosilicon} compounds having no active hydrogen used in the present invention can be represented, for example, by ^the _{formula R1xR2ySi} ⁽ _OR3 ) _z ( ^R1 and ^R2 are each independently a hydrocarbon group or a halogen, ^R3 is a hydrocarbon group, and 0≦x<2, 0≦y<2, and 0<z≦4).

Specific examples of 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, phenyl Trimethoxysilane, γ-chloropropyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, vinyltriethoxysilane, t-butyltriethoxysilane, n-butyltriethoxysilane, iso-butyltriethoxysilane, decyltriethoxysilane, cyclopentyltriethoxysilane, cyclohexyltriethoxysilane, 2-norbornanetriethoxysilane, phenyltriethoxysilane, γ-aminopropyltriethoxysilane, chlorotriethoxysilane, ethyltriisopropoxysilane, vinyltributoxysilane, trimethylphenoxysilane, methyltriallyloxy(allyoxy)silane, vinyltris(β-methyl) 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 Examples of such silane include t-amylmethyldiethoxysilane, dicyclopentyldiethoxysilane, diphenyldiethoxysilane, bis-p-tolyldiethoxysilane, cyclohexylmethyldiethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, tricyclopentylmethoxysilane, tricyclopentylethoxysilane, dicyclopentylmethylmethoxysilane, dicyclopentylethylmethoxysilane, hexenyltrimethoxysilane, cyclopentyldimethylmethoxysilane, cyclopentyldiethylmethoxysilane, dicyclopentylmethylethoxysilane, cyclopentyldimethylethoxysilane, and dimethyltetraethoxydisiloxane.

Among these, tetramethoxysilane, tetraethoxysilane, cyclohexylmethyldimethoxysilane, etc. are preferably used. Tetraethoxysilane is particularly preferably used in terms of catalytic activity.

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. It is also possible to use other compounds that can generate an organosilicon compound having no active hydrogen in the process of preparing the solid titanium catalyst component.

(d) Other Electron Donors In the present invention, in preparing the solid titanium catalyst component, it is preferable to use the above-mentioned organosilicon compound (c) having no active hydrogen, but other electron donors (d) having no active hydrogen can also be used.

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, and pyridines. 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, phenyl benzoate, benzyl benzoate, methyl toluate, ethyl toluate, organic acid esters having 2 to 18 carbon atoms, such as ethyl benzoate, 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 ether, ethyl ether, isopropyl ether, butyl ether, amyl ether, tetrahydrofuran, ethyl benzyl ether, and ethylene glycol dibutyl ether; Ethers having 2 to 20 carbon atoms, such as anisole and diphenyl ether; ketones having 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; trimethyl phosphite, triethyl phosphite, tri-n-propyl phosphite, triisopropyl phosphite, tri-n-butyl phosphite, and triisobutyl phosphite. Examples of suitable phosphates include phosphites such as diethyl n-butyl phosphite, diethylphenyl phosphite, and other phosphate esters, such as trimethyl phosphate, triphenyl phosphate, and tritolyl phosphate, acid amides such as N,N-dimethylamide acetate, N,N-diethylamide benzoate, and N,N-dimethylamide toluic acid, 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.

(Preparation of solid titanium catalyst component (A))
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 moles per mole 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 moles or less per mole 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.

In the present invention, when the components are 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 upon contact without the addition of 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, and 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), and more preferably 5 moles or more.

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 already contain an organosilicon compound (c). In this case, it is not necessary to add an 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.

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 so that a solid is not rapidly formed by this 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. If the contact temperature is too low at the beginning of the contact and a solid does not precipitate in the contact product (i), the contact can be continued for a long time at a low temperature to precipitate a solid.

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 also varies greatly depending on factors such as the scale of the reactor.

When liquid magnesium compound (a) is contacted with liquid titanium compound (b) in the presence of organosilicon compound (c) that does not have active hydrogen under these conditions, a granular or spherical solid titanium catalyst component with a relatively large particle size and good particle size distribution can be obtained. When ethylene is slurry polymerized using such a solid titanium catalyst component with excellent particle properties, an ethylene polymer with a granular or spherical shape, excellent particle size distribution, high bulk density and good fluidity can be obtained.

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

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 0.5 to 50, preferably 1 to 40, more preferably 2 to about 30, the halogen/titanium (atomic ratio) is 4 to 50, preferably 5 to 40, more preferably 6 to 30, and the organosilicon compound (c)/titanium (molar ratio) is 0.01 to 50, preferably 0.02 to 10, more preferably 0.03 to 6. The organosilicon compound (c)/magnesium (molar ratio) is preferably about 0.001 to 1, preferably about 0.002 to about 0.5, and particularly preferably 0.005 to 0.1.

The solid titanium catalyst component may contain other components, such as a carrier, in addition to the above components. Specifically, the other components may be contained in an amount of 50% by mass or less, preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass 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 at room temperature for 2 hours or more under conditions of 0.1 to 1 Torr.

The solid titanium catalyst component according to the present invention is desirably in the form of granules or nearly spherical, and has a specific surface area of about 10 ^m2 /g or more, preferably about 100 to 1000 ^m2 /g. In the present invention, the solid titanium catalyst component is usually used after washing with a hydrocarbon solvent.

(Olefin Polymerization Catalyst)
The olefin polymerization catalyst according to the present invention is formed from the above-mentioned solid titanium catalyst component (A) and an organoaluminum compound (B). The organoaluminum compound used in the present invention is specified by the following formula (1).
R ₃ Al... (1)
(The above R is a hydrocarbon group having 1 to 20 carbon atoms, such as an alkyl group, a cycloalkyl group, or an aryl group, as well as a substituent selected from the group containing a halogen atom.)

In addition, in the present invention, a halogen atom includes an embodiment as a substituent that can be expressed, for example, in the case of a chlorine atom, as "Cl-" (the "-" symbol represents a covalent bond).

In the present invention, at least one of R is a substituent having a molecular weight (in the case of a halogen atom, this corresponds to the atomic weight) of 30 or more. The lower limit of the molecular weight is preferably 32, more preferably 35, and particularly preferably 37. There is no particular restriction on the upper limit of the molecular weight, but it is preferably 300, more preferably 250, even more preferably 200, particularly preferably 150, and especially preferably 100.
Preferably, all R are substituents having a molecular weight of 30 or more.

Specific examples of the substituents include n-propyl, isopropyl, isobutyl, pentyl, hexyl, octyl, cyclopentyl, cyclohexyl, phenyl, tolyl, fluorine, chlorine, bromine, and iodine atoms, and essential substituents include n-propyl, isopropyl, isobutyl, pentyl, hexyl, octyl, cyclopentyl, cyclohexyl, phenyl, tolyl, chlorine, bromine, and iodine atoms. In addition to the above substituents, methyl and ethyl groups may be included.

Specific examples of essential organoaluminum compounds among these organoaluminum compounds include trialkylaluminums such as triisopropylaluminum, triisobutylaluminum, trioctylaluminum, and tri-2-ethylhexylaluminum; alkenylaluminums such as isoprenylaluminum; dialkylaluminum halides such as dimethylaluminum chloride, diethylaluminum chloride, diisopropylaluminum chloride, and diisobutylaluminum chloride; 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 diisobutylaluminum hydride. The above organoaluminum compounds can also be used in combination with organoaluminum compounds containing only substituents with a molecular weight of less than 30, such as trimethylaluminum, triethylaluminum, and diethylaluminum hydride.

The above-mentioned organoaluminum compounds are suitable examples for the present invention. Among the above, organoaluminum compounds having relatively small substituents such as triisopropylaluminum, triisobutylaluminum, trioctylaluminum, diethylaluminum chloride, and ethylaluminum sesquichloride are preferred.

Further, examples of the organoaluminum compound include compounds represented by the following formula:
R ^a _n A l Y _3-n
In the above formula, R ^a is the same as above, Y is a -OR ^b group, a -OSiR ^c ₃ group, a -OAlR ^d ₂ group, a -NR ^e ₂ group, a -SiR ^f ₃ group, or a -N(R ^g )AlR ^h ₂ group, n is 1 to 2, R ^b , R ^c , R ^d and R ^h are methyl groups, ethyl groups, isopropyl groups, isobutyl groups, cyclohexyl groups, phenyl groups, etc., R ^e is hydrogen, methyl groups, ethyl groups, isopropyl groups, phenyl groups, trimethylsilyl groups, etc., and R ^f and R ^g are methyl groups, ethyl groups, etc.

As such an organoaluminum compound, specifically, the following compounds are used:
(i) R ^a _n Al (OR ^b ) _3-n
Dimethylaluminum methoxide, diethylaluminum ethoxide, diisobutylaluminum methoxide, etc.
(ii) R ^a _n Al (OSiR ^c ₃ ) _3-n
Et ₂ Al (OSiMe ₃ ), (iso-Bu) ₂ Al (OSiMe ₃ ), (iso-Bu) ₂ Al (OSiEt ₃ ), etc.
(iii) R ^a _n Al (OAlR ^d ₂ ) _3-n
Et ₂ AlOAlEt ₂ , (iso-Bu) ₂ AlOAl(iso-Bu) ₂ , etc.
(iv) R ^a _n Al (NR ^e ₂ ) _3-n
Me ₂ AlNEt ₂ , Et ₂ AlNHMe, Me ₂ AlNHEt, Et ₂ AlN(Me ₃ Si) ₂ , (iso-Bu) ₂ AlN(Me ₃ Si) ₂ , etc.
(v) R ^a _n Al (SiR ^f ₃ ) _3-n
(iso-Bu) _2AlSiMe3 , _etc.
(vi) R ^a _n Al [N (R ^g ) - AlR ^h ₂ ] _3-n
Et ₂ AlN(Me)-AlEt ₂ , (iso-Bu) ₂ AlN(Et)-Al(iso-Bu) ₂ and the like.

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, ( _C2H5 ) _2AlOAl ( _C2H5 ) ₂ , _{( C4H9 ) 2AlOAl ( C4H9} ) ₂ , ( _{C2H5 ) 2AlN} ( _C2H5 )Al( _C2H5 ) ₂ , and aluminoxanes such as _{methylaluminoxane} .

Examples of the alkyl complexes of Group I metals and aluminum include compounds represented by the following general formula:
M ¹ A l R ^j ₄
( ^M1 is Li, Na, or K, and ^Rj is a hydrocarbon group having 1 to 15 carbon atoms.)

Specific examples of such compounds include LiAl(C ₂ H ₅ ) ₄ and LiAl(C ₇ H ₁₅ ) ₄ .
These compounds may be used in combination of two or more kinds.
The above R ^j is preferably a so-called hydrocarbon group containing only carbon and hydrogen.

In the present invention, the above-mentioned organoaluminum compounds may be used in combination with other organometallic compounds as required. For example, in addition to trimethylaluminum and triethylaluminum, examples of organometallic compounds of Group 2 metals include compounds represented by the following general formula:
R ^k R ^l M ²
(R ^k and R ^l are a hydrocarbon group having 1 to 15 carbon atoms or a halogen, and may be the same or different, except that both are halogen. M ² is Mg, Zn, or Cd.)

Specific examples include diethyl zinc, diethyl magnesium, butylethyl magnesium, ethyl magnesium chloride, and butyl magnesium chloride.
In this case, the proportion of other aluminum compounds, calculated as metal atoms such as aluminum and magnesium, is preferably 50 mol % or less of the R ₃ Al, more preferably 30 mol % or less, further preferably 10 mol % or less, and particularly preferably 5 mol % or less.

The ethylene polymerization catalyst according to the present invention may contain prepolymerized olefins. The ethylene polymerization catalyst according to the present invention may contain other components useful for the polymerization of ethylene in addition to the above-mentioned components.

<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 the above-mentioned solid titanium catalyst component (A) and organoaluminum compound (B). Specifically, a preferred embodiment is one in which ethylene is copolymerized with an olefin having 3 or more carbon atoms.

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.

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 solid titanium catalyst component (A) (or prepolymerization catalyst) is preferably used in an amount of usually about 0.0001 to 1.0 millimole, calculated as titanium atoms, per liter of polymerization volume. The organoaluminum compound (B) is preferably used in an amount such that the aluminum atoms in the catalyst component (B) are usually about 1 to 2,000 moles, preferably about 5 to 500 moles, per mole of titanium atoms in the solid titanium catalyst component (A) in the polymerization system.

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. Specific examples of the organic solvent that can be used include aliphatic hydrocarbons such as propane, butane, pentane, hexane, heptane, octane, decane, dodecane, and kerosene, alicyclic hydrocarbons such as cyclopentane, cyclohexane, and methylcyclopentane, aromatic hydrocarbons such as benzene, toluene, and xylene, and halogenated hydrocarbons such as ethylene chloride and chlorobenzene. These may be used in combination. Copolymerization monomers that are liquid at the reaction temperature can also be used together with the organic solvent.

Although the polymerization conditions vary depending on the form of polymerization or the type of the ethylene polymer to be obtained, the polymerization is usually carried out at a temperature of about 20 to 300°C, preferably about 50 to 150°C, under a pressure of normal pressure to 100 kg/ ^cm2 , preferably about 2 to 50 kg/ ^cm2 .

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

In the present invention, when polymerizing olefins, a catalyst is formed using the specific solid titanium catalyst component (A) described above, which allows the production of specific olefin polymers as described below with extremely high polymerization activity. As a result, 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 resulting ethylene polymer has a low fine powder content and excellent particle properties, so it may be used without pelletizing.

<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 99.8 mol% or less;
(PE2) The content of structural units derived from olefins having 3 to 20 carbon atoms is 0.2 mol% or more and 10 mol% or less (however, the total of the structural units derived from ethylene and the structural units derived from olefins having 3 to 20 carbon atoms is 100 mol%).
(D) Density is 900 to 960 kg/ ^m3
(H) The content of components having a molecular weight of 10 ^6.5 or more as determined by GPC measurement is 1.5 mass % or more.

(PE1) The preferred lower limit of the ethylene-derived structural unit content is 93% by mass, more preferably 95% by mass, and even more preferably 97% by mass. On the other hand, the preferred upper limit is 99.5% by mass.

(PE2) The preferred lower limit of the content of structural units derived from olefins having 3 to 20 carbon atoms is 0.5% by mass. On the other hand, the preferred upper limit is 8% by mass, more preferably 6% by mass, and even more preferably 5% by mass.

The content of the structural unit derived from the olefin as described above is determined by NMR measurement using a ¹³ C NMR device, assigning peaks characteristic of the corresponding olefin in a conventional manner, and then by area quantification. Alternatively, if IR measurement is performed on various olefin polymers having different compositions and a calibration curve is prepared, the content of the structural unit derived from the olefin can also be determined by IR measurement. In the examples of the present invention, the content of the structural unit derived from the olefin is determined by the latter method using IR measurement.

The lower limit of the content of (H) components having a molecular weight of ^106.5 or more as determined by GPC measurement is preferably 2.0% by mass, more preferably 2.2% by mass, even more preferably 2.5% by mass, particularly preferably 2.8% by mass, and especially preferably 3% by mass, while the upper limit is preferably 30% by mass, more preferably 25% by mass, even more preferably 22% by mass, and particularly preferably 20% by mass.

The GPC measurement conditions in the present invention are as follows.
Apparatus: GPC-IRR 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 )
Column: 2x TSKgel GMH6-HT + 2x TSKgel GMH6-HTL (7.5 mm I.D. x 30 cm, Tosoh)
Column temperature: 150 ° C.
Mobile phase: o-dichlorobenzene (ODCB), BHT added Flow rate: 1.0 mL/min
Sample concentration: 10 mg/20 mL (0.5 mg/mL)
Melting conditions: 145℃, 120min
Sample filtration: 1.0 μm sintered filter Injection volume: 0.4 mL
Column calibration: monodisperse polystyrene (TSKgel standard polystyrene; Tosoh)
The above content can be obtained by analyzing the obtained chromatogram by a known method.
In addition, since the above method also uses an FT-IR device, information such as branching in each molecular weight component can be obtained.

By using the method for producing an olefin polymer of ^the present invention, it is possible to obtain a polymer having a relatively high content of structural units derived from olefins having 3 or more carbon atoms, even if the polymer has a high molecular weight in the range of a molecular weight exceeding 10 6.5. 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.

It is known that high molecular weight components having a molecular weight of more than ^106.5 have excellent durability against deformation, such as "impact resistance", but since olefins having 3 or more carbon atoms tend to have a slower reaction rate than ethylene, it appears that in the conventional methods for producing olefin polymers using olefin polymerization catalysts containing a solid titanium catalyst component, it has tended to be difficult to obtain high molecular weight olefin polymer components having a molecular weight of more than 1 million, which have a relatively high content of structural units derived from olefins having 3 or more carbon atoms and/or little variation in said content depending on molecular weight (see Comparative Examples described later).

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 and toughness. Hereinafter, such components may be referred to as component (HB).
Furthermore, it is preferable that the amount of branching is relatively stable regardless of the molecular weight of the olefin polymer. Such a tendency can be judged, for example, by whether the curve showing the relationship between molecular weight and branching in the GPC-IR measurement chart in Figure 1 is relatively gentle.

According to the investigations of the present inventors, the use of an olefin polymerization catalyst containing a specific organoaluminum compound tends to easily give a polymer containing the above-mentioned component (HB).
Although the exact reason why an olefin polymer having such characteristics is obtained is unclear, the present inventors speculate as follows.

In solid titanium catalyst components such as those having the above-mentioned ORa substituents or silicon-containing components, the reduction rate of the titanium in the solid titanium catalyst component by the organoaluminum compound is relatively slow, so it is thought that the titanium that forms the active site tends to maintain a trivalent or tetravalent state, which is considered to have relatively good copolymerizability, but this is probably not sufficient. (The catalyst disclosed in Patent Document 1 may have had a strong tendency in this regard.)

When an organoaluminum compound such as that of the present invention is used in combination with a solid titanium catalyst component, the reduction rate of titanium as described above is further decreased, and active sites with high copolymerizability can exist more stably, which may make it easier to give an olefin polymer containing the above-mentioned component (HB). In addition, the fact that there is little change in the valence of the active sites is thought to allow the polymerization reaction to proceed stably, which may indicate a tendency to easily produce a high molecular weight product.

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 ASTS D1238E, 190° C.) is desirably 0.01 to 100 g/10 min.
The intrinsic viscosity [η] measured in decalin at 135° C. is preferably 1.5 to 10 dl/g, more preferably 2.0 to 8 dl/g.

The olefin polymer, particularly the ethylene copolymer, obtained in the present invention has the above-mentioned structural characteristics, and therefore, even if the content of the olefin having 3 or more carbon atoms is similar, the content of the component that melts at a low temperature tends to be high. Such a tendency can be confirmed by measuring the relationship between the ambient temperature and the heat of fusion by the DSC method described in the examples below,
(β) The heat of fusion at 100° C. or less and (γ) the heat of fusion at 125° C. or more can be confirmed as indicators.

The ethylene copolymers produced by the method of the present invention tend to have a relatively large value of (β) and a relatively small value of (γ). This is thought to be because structural units derived from olefins having 3 or more carbon atoms are relatively dispersed in the ethylene copolymer (corresponding to a tendency for the composition distribution to be narrow).

The ethylene polymer obtained by the present invention as described above can also be blended with heat stabilizers, weather stabilizers, antistatic agents, antiblocking agents, lubricants, nucleating agents, pigments, dyes, inorganic or organic fillers, etc., as necessary.

If it is within the above range, it can be suitably used as a raw polymer for films, containers, etc. It is particularly suitable as a raw polymer for containers obtained by blow molding, etc.

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. In the following examples, the composition of the solid titanium catalyst component, the intrinsic viscosity [η] of the ethylene polymer, the bulk density, density, and butene content were measured as follows.

(1) Mg and Ti Contents These were measured by ICP analysis (Shimadzu Corporation, ICPF 1000TR).

(2) Cl content: Measured by silver nitrate titration.

(3) OR Group Content A thoroughly dried catalyst was added to an acetone solution containing 10% by weight of water, and the ROH obtained by hydrolysis was quantitatively determined by gas chromatography.

(4) Intrinsic viscosity [η]
The intrinsic viscosity [η] was measured in decalin at 135° C. by dissolving the ethylene polymer in decalin and using a fully automatic viscosity measuring device (Rigosha, VMR-053UPC).

(5) Bulk density: Measured according to JIS K 6721.

(6) Density Using a hydraulic hot press set at 190°C, the sample was heated and melted at a pressure of 5 MPa, and then cooled at a pressure of 15 MPa and an average cooling rate of 15±5°C/min to produce a pressed sheet. (Spacer shape: 65×12×2 (mm) on a 200×200×2 (mm) thick plate, 4 pieces were cut.)
The pressed sheet was boiled for 30 minutes, and then cooled together with the boiled water in a laboratory atmosphere for at least 1 hour, after which the density was measured using a density gradient tube.

(7) Content of butene-derived structural units The comonomer content of the copolymer was measured by FT-IR (FT-IR4100 type infrared spectrophotometer manufactured by JASCO Corporation).
FT-IR was measured at a light source wavelength of 5000 cm -1 to 400 cm -1 using a film obtained by melt-stretching the copolymer produced in the examples in a hot press heated to 180°C and then cooling under pressure at room ^temperature as a measurement sample. The butene content was measured by determining the C-CH ₂ CH ₃ skeletal vibration (1378 cm ^-1 ) based on butene as the key band and calculating the ratio [D1378/D4321] of the absorbance of the key band (D1378) to the absorbance of the internal standard ^band (4321 cm ^-1 : the combination sound of C-H stretching vibration and methylene and methyl bending vibration).
Meanwhile, for several types of ethylene/butene copolymers whose contents of butene-derived structural units were known in advance by a method such as ^13C NMR, the [D1378/D4321] values were obtained by the above-mentioned method, and a calibration curve relating to the relationship between the [D1378/D4321] value and the butene content was prepared 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.

Further, the ethylene polymer was subjected to DSC measurement and GPC-IR measurement according to the following methods.
<DSC Measurement>
A differential scanning calorimeter (PerkinElmer DSC8000) was used, and the SSA (Successive Self-Nucleation/Annealing) method described in European Polymer Journal 65 (2015) 132-154 was used.
"Setting Ts (Self-seeding and annealing) temperature"
The temperature was increased from 20° C. to 200° C. at 25° C./min, held at 200° C. for 5 minutes, then decreased from 200° C. to 30° C. at 25° C./min, held at 30° C. for 2 minutes, and increased from 20° C. to 150° C. at 10° C./min. The temperature above the melting point at which the endothermic peak became zero was set as the Ts temperature.
“SSA (Successive Self-Nucleation/Annealing) method”
The sample after Ts temperature measurement was heated from 20 ° C. to 200 ° C. at 25 ° C. / min, held at 200 ° C. for 5 minutes, then cooled from 200 ° C. to 30 ° C. at 25 ° C. / min, held at 30 ° C. for 2 minutes, heated from 30 ° C. to Ts temperature at 10 ° C. / min, and held at Ts temperature for 5 minutes. The temperature was lowered from Ts temperature to Ts-35 ° C. at 10 ° C. / min, held at Ts-35 ° C. for 2 minutes, heated from Ts-35 ° C. to Ts-5 ° C. at 10 ° C. / min, and held at Ts-5 ° C. for 5 minutes. Next, the temperature was lowered from Ts-5 ° C. to Ts-40 ° C. at 10 ° C. / min, held at Ts-40 ° C. for 2 minutes, heated from Ts-40 ° C. to Ts-10 ° C. at 10 ° C. / min, and held at Ts-10 ° C. for 5 minutes. Such an operation was repeated a total of 11 times at 5 ° C. intervals. Finally, the temperature was lowered from Ts-55°C to 30°C at a rate of 10°C/min, held at 30°C for 2 minutes, and then raised from 30°C to 200°C at a rate of 10°C/min.
The total heat of fusion calculated from the obtained melting endothermic peak is ΔH, the heat of fusion at 125° C. or higher is ΔH125, and the heat of fusion at 100° C. or lower is ΔH100.
Crystalline component rate at 125°C or higher = (ΔH125/ΔH) x 100%
Crystalline component rate below 100°C = (ΔH100/ΔH) x 100%
It was calculated as:

<GPC-IR Measurement>
Apparatus: GPC-IRR 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 )
Column: 2x TSKgel GMH6-HT + 2x TSKgel GMH6-HTL (7.5 mm I.D. x 30 cm, Tosoh)
Column temperature: 150 ° C.
Mobile phase: o-dichlorobenzene (ODCB), BHT added Flow rate: 1.0 mL/min
Sample concentration: 10 mg/20 mL (0.5 mg/mL)
Melting conditions: 145℃, 120min
Sample filtration: 1.0 μm sintered filter Injection volume: 0.4 mL
Column calibration: monodisperse polystyrene (TSKgel standard polystyrene; Tosoh)

[Synthesis Example 1]
"Preparation of solid titanium catalyst component (A)"
The solid titanium catalyst component (A) was prepared in the same manner as in the Examples of JP-A-9-328514. The composition of the obtained solid titanium catalyst component (A) is shown in Table 1.

[Example 1]
In a 1-liter autoclave, 500 ml of purified n-heptane was charged under a nitrogen atmosphere, and 0.78 mmol of triisobutylaluminum (molecular weight of isobutyl group: 57.12) 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 with stirring, and 0.01 MPa of hydrogen diluted with nitrogen was fed to a hydrogen concentration of 5 mol%, followed by continuous feeding of an ethylene-butene mixed gas with a butene concentration of 2 mol% so that the total pressure became 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, 24.2 g of a powdery polymer was obtained. The intrinsic viscosity [η] of this powdery polymer was 7.6 dl/g, the density was 926 kg/m ³ , the butene content was 6.9/1000C, and the apparent bulk density was 0.29 g/cc. The results are shown in Table 2. The results of the DSC analysis and the GPC-IR analysis of this powdery polymer are shown in Table 2, and the GPC-IR measurement chart is shown in FIG. 1.

[Example 2]
Polymerization was carried out in the same manner as in Example 1, except that diethylaluminum chloride (atomic weight of chlorine: 35.453) was used instead of triisobutylaluminum during polymerization. The results are shown in Table 2.

[Example 3]
Polymerization was carried out in the same manner as in Example 1, except that hydrogen diluted with nitrogen to a hydrogen concentration of 5 mol % was supplied at 0.05 MPa, and then an ethylene-butene mixed gas having a butene concentration of 2 mol % was continuously supplied so that the total pressure became 0.14 MPaG. The results are shown in Table 2.

[Example 4]
Polymerization was carried out in the same manner as in Example 2, except that hydrogen diluted with nitrogen to a hydrogen concentration of 5 mol % was supplied at 0.10 MPa, and then an ethylene-butene mixed gas having a butene concentration of 2 mol % was continuously supplied so that the total pressure became 0.19 MPaG. The results are shown in Table 2.

[Comparative Example 1]
Polymerization was carried out in the same manner as in Example 1, except that triethylaluminum was used instead of triisobutylaluminum during polymerization. The results are shown in Table 2, and the GPC-IR measurement chart is shown in FIG.

[Synthesis Example 2]
"Preparation of solid titanium catalyst component (B)"
The solid titanium catalyst component (B) was prepared in the same manner as in the Examples of WO 2009/125729. The composition of the obtained solid titanium catalyst component (B) is shown in Table 1.

[Example 5]
Polymerization was carried out in the same manner as in Example 1, except that the solid titanium catalyst component (A) was changed to the solid titanium catalyst component (B) during polymerization. The results are shown in Table 2.

[Comparative Example 2]
The polymerization was carried out in the same manner as in Example 5, except that triethylaluminum (molecular weight of ethyl group: 29.06) was used instead of triisobutylaluminum during the polymerization. The results are shown in Table 2.

[Synthesis Example 3]
"Preparation of solid titanium catalyst component (C)"
The solid titanium catalyst component (C) was prepared in the same manner as in the Examples of WO 2008/013144. The composition of the obtained solid titanium catalyst component (C) is shown in Table 1.

[Example 6]
Polymerization was carried out in the same manner as in Example 1, except that the solid titanium catalyst component (A) was changed to the solid titanium catalyst component (C) during polymerization. The results are shown in Table 2.

[Comparative Example 3]
The polymerization was carried out in the same manner as in Example 6, except that triethylaluminum was used instead of triisobutylaluminum during the polymerization. The results are shown in Table 2.

From the attached FIG. 1, it can be seen that the olefin polymer obtained by using the olefin polymerization catalyst of the present invention has a relatively high content of structural units having 3 or more carbon atoms even in a high molecular weight region of 10 ^or more, and furthermore, the content of the structural units is relatively constant regardless of the molecular weight.

Claims (4)

(A) containing magnesium, titanium, and a halogen;
10 to 25% by mass of magnesium,
Titanium: 2 to 12 mass%;
1 to 12% by mass of ORa groups (wherein Ra is a hydrocarbon group having 1 to 20 carbon atoms); and
(α) 0 to 12% by mass of a compound selected from a silicon-containing compound, an organic acid compound, an organic acid ester compound, a ketone compound, an aldehyde compound, a nitrogen-containing compound, and a phosphorus-containing compound
A solid titanium catalyst component comprising:
(B) An organoaluminum compound represented by the following formula (1) and R ₃ Al (1)
(wherein R is a substituent containing carbon, hydrogen, or a heteroatom, at least one of which has a molecular weight of 30 or more.)
A method for producing an olefin polymer which satisfies the following requirements (PE1), (PE2), (D), and (H), by 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 99.8 mol% or less;
(PE2) the content of structural units derived from olefins having 3 to 20 carbon atoms is 0.2 mol % or more and 10 mol % or less (provided that the total of the structural units derived from ethylene and the structural units derived from olefins having 3 to 20 carbon atoms is 100 mol %);
(D) density of 900 to 960 kg/m ³ ;
(H) The content of components having a molecular weight of 10 ^6.5 or more as determined by GPC measurement is 1.5 mass % or more. The method for producing an olefin polymer according to claim 1, wherein at least one of R in formula (1) has a molecular weight of 35 or more and 300 or less. The method for producing an olefin polymer according to claim 1, wherein at least one of R in formula (1) is a hydrocarbon group consisting of carbon atoms and hydrogen atoms. The method for producing an olefin polymer according to claim 1, wherein the (A) solid titanium catalyst component is a solid titanium catalyst component obtained by contacting (a) a liquid magnesium compound with (b) a liquid titanium compound in the presence of (c) an organosilicon compound having no active hydrogen in an amount of 0.25 to 0.35 moles per mole of the magnesium compound (a), and heating the resulting contact product (i) to a temperature in the range of 105 to 115°C and maintaining it at this temperature.