JPH10330417A - Production of ethylene-based polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polyethylene or ethylene copolymer prevented from adhering to polymerizer wall and having high bulk density. SOLUTION: This method comprises a polymerization of ethylene by the use of a catalytic system as a combination of an organoaluminum compound with a solid catalytic component, wherein the solid catalytic component is prepared by prepolymerization, in the presence of an organoaluminum compound, between an α-olefin and a solid catalytic component formed by treating with a halogenating agent a hydrocarbon solution essentially containing (a) a magnesium compound of the formula Mg(OR<1> )k X2-k (R<1> is an alkyl, aryl or cycloalkyl; X is a halogen; (k) is 0, 1 or 2) and (b) a polyalkyl titanate compound of the formula (R<2> is an alkyl, aryl or cycloalkyl; (l) is 2-20) in the presence or absence of (c) a titanium compound of the formula Ti(OR<3> )m X4-m (R<3> is an alkyl, aryl or cycloalkyl; X is a halogen; (m) is 1, 2, 3 or 4).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an ethylene polymer, and more particularly to a method for producing an ethylene polymer having a high bulk density and excellent powder properties.

[0002]

2. Description of the Related Art Conventionally, the following problems have been encountered in the case of producing an ethylene-based polymer by performing polymerization using a Ziegler catalyst. (1) It was difficult to obtain a polyethylene or an ethylene copolymer having good slurry properties, especially a slurry having a high bulk density related to productivity. (2) Adhesion to the polymerization vessel wall may occur, making long-term continuous operation impossible, or significantly reducing productivity.

[0003]

SUMMARY OF THE INVENTION The present invention is based on the above problems, and as a result of intensive studies on the solution thereof, it has been found that adhesion to the wall of the polymerization vessel is prevented and polyethylene or ethylene copolymer having a high bulk density is obtained. The present invention has developed a method for producing polyethylene or an ethylene copolymer, which enables the production of polyethylene or an ethylene copolymer, which enables long-term stable continuous operation under high productivity.

[0004]

The present invention provides (I) (a)
A magnesium compound represented by the general formula Mg (OR ¹ ) _k X _2-k (R ¹ : an alkyl group, an aryl group, a cycloalkyl group,
X: halogen, k = 0, 1, 2) (b) General formula

[0005]

Embedded image

A polyalkyl titanate compound (R ² : an alkyl group, an aryl group, or a cycloalkyl group, which may be the same or different, 1 = 2 to 20) as an essential component; (OR ³ ) a titanium compound represented by _m X _4-m (R ³ : an alkyl group, an aryl group, a cycloalkyl group,
X: In the presence or absence of halogen, m = 1, 2, 3, 4), if necessary, represented by the general formula (d) R ⁴ OH (R ⁴ : alkyl group, aryl group, cycloalkyl group) A solid catalyst component obtained by treating a hydrocarbon solution containing an alcohol compound and leaving a homogeneous or partially heterogeneous portion with a halogenating agent is converted into an α-alkyl having 2 to 20 carbon atoms in the presence of (II) an organoaluminum compound. -Homopolymerizing ethylene or copolymerizing ethylene with another olefin using a catalyst system obtained by combining (III) a prepolymerized solid catalyst component obtained by prepolymerizing an olefin and (IV) an organoaluminum compound. In the method, the weight average molecular weight Mw of the polymer obtained by the
An object of the present invention is to provide a method for producing an ethylene-based polymer, which is not more than 100,000.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Preparation of solid catalyst component The magnesium compound (a) used for preparing the solid catalyst component (I) of the present invention has a general formula of Mg (OR ¹ ) _k X
A compound represented by _2-k (R ¹ : alkyl group, aryl group, cycloalkyl group, X: halogen, k = 0, 1, 2) is used. Specifically, R ¹ is an alkyl, aryl, or cycloalkyl group having up to about 15 carbon atoms such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, tolyl, xylyl, cyclohexyl, and X is chlorine, bromine, Or a compound which is iodine. Examples include diethoxymagnesium, ethoxymagnesium chloride, diphenoxymagnesium, magnesium chloride and the like. In the production of ordinary solid catalyst components, the particle size can be controlled arbitrarily according to the applicable process,
Particle size control is performed in a halogenation step described later. In such a case, the raw material before the halogenation step is preferably in a homogeneous solution state in a hydrocarbon solvent. In such a case, dialkoxymagnesium, which is a compound in which k = 2, is preferable. On the other hand, the halogenation step can be performed in a non-uniform state by using a raw material magnesium compound having a controlled particle size. As the polyalkyl titanate compound (b), a compound represented by the following general formula is used.

[0008]

Embedded image

(Wherein R ² represents an alkyl, aryl or cycloalkyl group, which may be the same or different.
L is an integer of 1 = 1 to 20. In the above formula, as R ² , those exemplified above for R ¹ can be similarly mentioned. Specifically, OR ² is a butoxy group, and 1 is 2, 4, 7, and 10, respectively, dimer-tetrabutoxytitanium, tetramer-tetrabutoxytitanium, heptamer-tetrabutoxytitanium, decamer-tetrabutoxytitanium, and , OR ² is a propoxy group and l is 2,
4, 7, and 10, dimer-tetrapropoxytitanium, tetramer-tetrapropoxytitanium, heptamer-tetrapropoxytitanium, decamer-tetrapropoxytitanium, and the like. Among them, tetramer-tetrabutoxytitanium, heptamer-tetrabutoxytitanium, decamer-tetrabutoxytitanium, tetramer-tetrapropoxytitanium, heptamer-tetrapropoxytitanium, decamer-tetrapropoxytitanium and the like are preferable.
Further, a condensate of tetraalkoxytitanium obtained by reacting a small amount of H ₂ O with tetraalkoxytitanium (the same compound as that described later in (c)) can be used.

In order to adjust the halogenation rate and the liquid viscosity in the later-described halogenation step, a titanium compound (c) represented by the following general formula is usually used as necessary.

[0011]

(C) General formula Ti (OR ³ ) _m X _4-m

[0012] (R ^3: an alkyl group, an aryl group, may be the same or different a cycloalkyl group, X: halogen, m = 1, 2, 3, 4) said R ¹ is as R ^3, X, Those exemplified for X can be similarly mentioned. Specifically, tetraethoxytitanium, tetrapropoxytitanium, tetra-n-
Triethoxymonochlorotitanium, tripropoxymonochlorotitanium, m = 3 compounds such as butoxytitanium,
Triethoxy-dichlorotitanium, dipropoxydichlorotitanium, di-n-butoxydichlorotitanium, etc. as compounds with m = 2, ethoxytrichlorotitanium, propoxytrichlorotitanium, n as compounds with m = 1, such as tri-n-butoxymonochlorotitanium -Butoxytrichlorotitanium and the like, but compounds with m = 4 and 3 are preferred. Among them, tetra-n-butoxytitanium with m = 4, tri-n-butoxymonochlorotitanium with m = 3 and the like are preferable.

If necessary, an alcohol compound (d) represented by the following general formula is used for adjusting the affinity between the above-mentioned magnesium compound, polyalkyl titanate compound, titanium compound and a hydrocarbon solvent.

[0014]

(D) R ⁴ OH (where R ⁴ represents an alkyl, aryl or cycloalkyl group)

As R ⁴ , those exemplified for R ¹ can be similarly mentioned. Specific examples include ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, n-pentyl alcohol, n-octyl alcohol and the like.

The solid catalyst component used in the production of the polyethylene of the present invention contains the above magnesium compound, polyalkyl titanate compound, titanium compound in some cases, and, if necessary, alcohol compound. May leave some insoluble parts). As the hydrocarbon solvent used for this, hexane, heptane, aliphatic hydrocarbons such as octane,
Alicyclic hydrocarbons such as cyclohexane, aromatic hydrocarbons such as benzene, toluene, and xylene are used. In particular, non-halogenated hydrocarbons are desirable. In preparing a solution in a hydrocarbon solvent, the order of catalytic addition of a magnesium compound, a polyalkyl titanate compound, a titanium compound depending on the case, and an alcohol to be added as needed can be appropriately selected without any particular limitation. In order to obtain the above-mentioned hydrocarbon solution, it is preferable to heat the mixture in a temperature range of usually 20 to 170 ° C, more preferably 70 to 150 ° C, after adding and mixing the raw materials. If the temperature is lower than the above range, the solubility of the raw material may be extremely deteriorated, and the properties of the catalyst particles may be deteriorated. If the temperature is higher than the above range, the polyalkyl titanate compound (b) may be deteriorated, which is not preferable. The amount of the solvent used is the above magnesium compound (a), polyalkyl titanate compound (b),
The required amount is added so that the total molar amount of the titanium compound (c) satisfies the following range with respect to the solvent used.

0.01 (mol / L) ≦ {total molar amount of (a), (b) and (c)} (mol) / solvent amount (L) ≦ 4 (mol / L), preferably 0.01 (Mol / L) ≦ {total molar amount of (a), (b) and (c)} (mol) / solvent amount (L) ≦ 2 (mo
1 / L)

## EQU1 ## If the concentration is below the above range, the yield of the catalyst per used amount of the solvent is extremely low, which is not practical. Also,
If the concentration is higher than the above range, the liquid viscosity of the hydrocarbon solution increases, which may hinder handling. In some cases, any of a magnesium compound, a polyalkyl titanate compound, and a titanium compound may be added after the heating treatment.

The charge ratio of each raw material is usually set within the following molar ratio range. 0 ≦ titanium compound (c) / magnesium compound (a) ≦
5 0.25 ≦ polyalkyl titanate compound (b) / magnesium compound (a) ≦ 4, preferably 0 ≦ titanium compound (c) / magnesium compound (a) ≦
2 0.25 ≦ polyalkyl titanate compound (b) / magnesium compound (a) ≦ 2 More preferably, 0.25 ≦ titanium compound (c) / magnesium compound (a) ≦ 1 0.25 ≦ polyalkyl titanate compound ( b) / magnesium compound (a) ≦ 1.5.

Then, the homogeneous hydrocarbon solution or suspension obtained as described above is treated with a halogenating agent to obtain a solid catalyst component. The halogenating agent is not particularly limited as long as it has the action, but usually, III,
Examples include halides of group IV, V, and VI elements, hydrogen halides, and the like. Specific examples include chlorides such as titanium tetrachloride, silicon tetrachloride, tin tetrachloride, and vanadium tetrachloride, and chlorine-containing compounds such as hydrogen chloride. These may be used alone or in combination of two or more. Among them, titanium tetrachloride, silicon tetrachloride and the like are preferable.

The method of treating with these halogenating agents is not particularly limited, but the treatment is usually performed at a temperature in the range of 20 to 200 ° C, preferably 80 to 130 ° C. If the treatment is carried out at a temperature below the above, halogenation may be extremely insufficient, which is not preferable. If the treatment is carried out at a temperature higher than the above, the polyalkyl titanate (b) may deteriorate, which is not preferable. The halogenation treatment may be performed once or may be repeated twice or more.

The solid catalyst component produced as described above is separated and washed with a hydrocarbon solvent. Further, in the present invention, a small amount of an electron donating compound may be allowed to coexist at any stage before the solid catalyst component is generated, or after the solid catalyst component is generated, it is treated with a small amount of the electron donating compound. May be. Such electron donating compounds generally include phosphorus-containing compounds, oxygen-containing compounds, sulfur-containing compounds, nitrogen-containing compounds, and the like. Of these, an oxygen-containing compound is preferably used. As the oxygen-containing compound, for example, the following formula

[0023]

Embedded image R ⁵ OR ⁶ , R ⁵ COR ⁶ , R ⁵ (COOR ⁶ ) _p

(Wherein, R ⁵ and R ⁶ each represent a hydrocarbon group which may be substituted with an alkoxy group, and may be mutually bonded to form a cyclic group; and p is an integer of 1 to 3. Is shown.)
In particular, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, aromatic carboxylic acid esters such as diheptyl phthalate, or a metal salt of an aromatic carboxylic acid, ethyl phenylacetate, benzoic acid Carboxylic esters such as methyl, ethyl benzoate, methyl toluate, methyl anisate, ethyl anisate, methyl ethoxybenzoate, ethyl cinnamate, and silicon-containing carboxylic esters such as benzoic acid-β-trimethoxysilylethyl And the like. The amount of the electron-donating compound is not particularly limited, but is usually 10 mol or less, preferably 0.1 mol, per 1 mol of the magnesium compound.
It is chosen to be between 01 and 1 mol.

[0025] Using the catalyst described above in the prepolymerization process of the present invention, preliminary polymerization. As the hydrocarbon solvent used in the prepolymerization, an aliphatic hydrocarbon solvent, specifically, propane, isobutane, normal butane, normal pentane, isopentane, normal hexane, normal octane and the like, or a mixture thereof,
Examples thereof include alicyclic hydrocarbon solvents such as cyclopentane and cyclohexane, and among them, aliphatic hydrocarbon solvents having 4 to 6 carbon atoms are preferable.

The monomers used in the prepolymerization include:
Α-olefins having 2 to 20 carbon atoms or a mixture of these α-olefins. Examples of the α-olefin having 2 or more carbon atoms include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-
Decene and the like. Among them, ethylene alone or a mixture of ethylene and an α-olefin having 3 or more carbon atoms is preferable. More preferably, ethylene alone or ethylene and carbon number 3
Mixtures with α-olefins of from 6 to 6 are preferred.

Further, the prepolymerization is carried out in the presence of an organoaluminum compound. Such an organoaluminum compound has a general formula

[0028]

Embedded image ^{_{AlR 7 q X 5 3-q}} ( wherein, R ⁷ represents alkyl, aryl, a cycloalkyl group, X ⁵ represents a halogen atom, q is a number of 1-3.)

Specific examples include compounds represented by the following formulas: trialkylaluminums such as triethylaluminum, tri-n-propylaluminum, and triisobutylaluminum; diethylaluminum monochloride;
Examples thereof include diisobutylaluminum monochloride, ethylaluminum sesquichloride, and a reaction product of an organoaluminum compound and water. One of these organoaluminum compounds may be used, or two or more compounds may be used in combination.

The molecular weight of the polymer (pre-polymerized polymer) formed in the pre-polymerization is usually 1,000,000 or less, preferably 500,000 or less, more preferably 300,000 or less. If the molecular weight of the prepolymerized polymer is high, the bulk density of the produced polyethylene or ethylene copolymer is reduced, and at the same time, electrostatic aggregation of the prepolymerized catalyst may occur. For controlling the molecular weight of the prepolymerized polymer, a prepolymerized polymer having an arbitrary molecular weight is obtained depending on the type and amount of the organoaluminum compound used during the prepolymerization, hydrogenation, the prepolymerization temperature, and the like. The prepolymerization temperature is usually 0 ° C to 1 ° C.
00 ° C, preferably in the range of 40 ° C to 90 ° C.
The pressure may be 50 atm or less, and the polymerization time may be several minutes to several hours, but usually the pre-polymerization amount may be small, so that high pressure and long time are not required.

The prepolymerized solid catalyst component obtained as described above is used for homopolymerization of ethylene and copolymerization with an α-olefin in the presence of an organoaluminum compound. The polymerization form is not particularly limited as long as a target product can be obtained, but a slurry polymerization method in which an ethylene monomer is dissolved in a hydrocarbon solvent to carry out polymerization is usually used.

Hereinafter, a specific description will be given. The organoaluminum compound used may or may not be halogen containing. Typical examples are trialkylaluminums such as triethylaluminum, tripropylaluminum, tributylaluminum, trihexylaluminum, trioctylaluminum, dialkylaluminum hydrides such as diethylaluminum hydride and diisobutylaluminum, and dialkylaluminum halides such as diethylaluminum chloride. And the like. Of these organoaluminums, trialkylaluminums are preferred,
Triethylaluminum, triisobutylaluminum and the like are preferred. Further, two or more kinds of organoaluminum compounds may be used in combination.

As α-olefins other than ethylene, those having 3 to 20 carbon atoms can be used, and propylene, butene-1, pentene-1, hexene-1, octene-1, 4-methylpentene-1,3 Methylbutene-1,
Styrene and the like can be mentioned. Dienes can also be used. As described above, the polymerization reaction can be carried out by solution polymerization in addition to slurry polymerization performed in an inert hydrocarbon solvent. At this time, as the hydrocarbon solvent, butane, pentane, isopentane, hexane, heptane, aliphatic hydrocarbons such as octane, alicyclic hydrocarbons such as cyclohexane,
Aromatic hydrocarbons such as benzene, toluene and xylene are used.

The polymerization reaction is usually selected from a temperature range of 20 to 200 ° C. and a pressure range of 1 to 100 (kgf / cm ² ). In the present invention, a polymer having a desired molecular weight can be obtained by allowing hydrogen to be present in the polymerization reaction zone. Further, in the main polymerization, not only the one-stage polymerization method but also the polymerization
A multi-stage polymerization method involving more than two stages may be employed.

[0035]

【Example】

Example 1 (1) Preparation of solid catalyst component Mg (OEt) ₂ was added to a 50 L autoclave purged with nitrogen.
, 368 g of Ti (OBu) ₄ , 1838 g of tetrabutoxytitanium tetramer, and 12.8 L of normal hexane, and the mixture was heated to 105 ° C. with stirring and treated for 3 hours to obtain a uniform viscous liquid. . To this normal hexane solution, 7560 ml of T
iCl ₄ was added at 38 ° C. over 240 minutes. Subsequently, the temperature was raised to 105 ° C. and the treatment was performed for 5 hours. Next, after cooling to room temperature, the product was sufficiently washed with normal hexane to obtain 1310 g of a solid catalyst component.

(2) Preliminary polymerization 1 L of normal hexane was charged into a 2 L autoclave purged with nitrogen, and 15 g of the solid catalyst component was added.
The temperature was raised to 0 ° C. H ₂ was introduced at ² kgf / cm ^2, and 45 mmol of diethylaluminum monochloride was introduced together with ethylene to initiate polymerization. After introducing 15 g of ethylene over 60 minutes at an ethylene pressure in the range of 0 to 0.2 kgf / cm ² and performing prepolymerization, the ethylene was replaced with nitrogen to terminate the prepolymerization. Next, the prepolymerized catalyst was sufficiently washed with normal hexane to obtain 30 g of a prepolymerized solid catalyst component.

(3) Main polymerization 1 L was placed in a 2 L autoclave which had been sufficiently replaced with nitrogen gas beforehand.
L normal hexane and triethylaluminum
After the addition of 0.08 mmol, the temperature was raised to 90 ° C. H
_TwoTo 12 kgf / cm^TwoIntroduce the pre-polymerized catalyst component
60 milligrams were introduced together with ethylene to initiate the polymerization reaction.
Started. For polymerization, the total pressure is 22 kgf / cm ^TwoTo keep
Polymerization was performed at 90 ° C. for 2 hours while adding ethylene. Eta
After the polymerization was stopped by injecting toluene, the polymer was filtered off and dried.
Dried. Table 1 shows the results.

Example 2 The procedure of Example 1 was repeated except that the prepolymerization was carried out at 90 ° C. Table 1 shows the results.

Example 3 The procedure of Example 1 was repeated, except that the amount of diethyl aluminum monochloride used in the prepolymerization was changed to 60 mmol. Table 1 shows the results.

Example 4 The procedure of Example 1 was repeated except that the amount of the solid catalyst component used in the prepolymerization was changed to 30 g. Table 1 shows the results
Shown in

Example 5 The procedure of Example 1 was repeated except that the temperature of adding TiCl ₄ during the preparation of the solid catalyst component was changed to 50 ° C. Table 1 shows the results.

Example 6 Example 5 was carried out in the same manner as in Example 5 except that the alkyl aluminum used in the prepolymerization was changed to triethylaluminum and 30 mmol was used. Table 1 shows the results
Shown in

Comparative Example 1 The solid polymerization obtained in Example 1 was subjected to main polymerization under the same conditions as in Example 1 without preliminary polymerization. Table 1 shows the results.

Comparative Example 2 The solid polymerization obtained in Example 5 was subjected to main polymerization under the same conditions as in Example 5 without preliminary polymerization. Table 1 shows the results.

Comparative Example 3 Example 1 was carried out in the same manner as in Example 1 except that the amount of diethyl aluminum monochloride used in the prepolymerization was changed to 8.7 mmol. Table 1 shows the results.

Comparative Example 4 Example 5 was repeated except that the amount of diethyl aluminum monochloride used in the prepolymerization was changed to 15 mmol.
Was performed in the same manner as described above. Table 1 shows the results.

Comparative Example 5 The procedure of Comparative Example 4 was repeated except that the prepolymerization temperature was changed to 50 ° C. Table 1 shows the results.

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

[Brief description of the drawings]

FIG. 1 is a flowchart for helping the understanding of the present invention.

Claims (2)

[Claims] (I) (a) The general formula Mg (OR ¹ ) _k X
A magnesium compound represented by _2-k (R ¹ : an alkyl group, an aryl group, a cycloalkyl group,
X: halogen, k = 0, 1, 2) (b) General formula A polyalkyl titanate compound represented by the formula (R ² : an alkyl group, an aryl group, or a cycloalkyl group, which may be the same or different and 1 = 2 to 20) is an essential component, and (c) a general formula Ti (OR ³ ) A titanium compound represented by _m X _4-m (R ³ : an alkyl group, an aryl group, a cycloalkyl group,
X: In the presence or absence of halogen, m = 1, 2, 3, 4), if necessary, represented by the general formula (d) R ⁴ OH (R ⁴ : alkyl group, aryl group, cycloalkyl group) A solid catalyst component obtained by treating a hydrocarbon solution containing an alcohol compound and leaving a homogeneous or partially heterogeneous portion with a halogenating agent is converted into an α-alkyl having 2 to 20 carbon atoms in the presence of (II) an organoaluminum compound. A method of homopolymerizing ethylene or copolymerizing ethylene with another olefin using a catalyst system obtained by combining (III) a prepolymerized solid catalyst component obtained by prepolymerizing an olefin and (IV) an organoaluminum compound. A method for producing an ethylene-based polymer, wherein the weight average molecular weight Mw of the polymer obtained by the prepolymerization measured by GPC is 1,000,000 or less. 2. The method for producing an ethylene polymer according to claim 1, wherein the weight average molecular weight Mw of the polymer obtained by the preliminary polymerization is 300,000 or less.