WO2009124722A1

WO2009124722A1 - Method for preparing a titanium catalyst component, titanium catalyst component, method for preparing a titanium catalyst and titanium catalyst

Info

Publication number: WO2009124722A1
Application number: PCT/EP2009/002566
Authority: WO
Inventors: Qi Guo; Yong Jiang
Original assignee: Sued Chemie AG
Current assignee: Sued Chemie AG
Priority date: 2008-04-07
Filing date: 2009-04-07
Publication date: 2009-10-15
Anticipated expiration: 2010-10-07
Also published as: CN102272172A; DE112009000794T5

Abstract

The present invention relates to a method for preparing a titanium catalyst component, comprising the steps: reacting a magnesium halide in a solvent including an alcohol to obtain a homogeneous solution, reacting at least one organic boron compound with the homogeneous solution, reacting a titanium compound with the homogeneous solution, a titanium catalyst component obtainable by said method, a method for preparing a titanium catalyst and a titanium catalyst obtainable by said method.

Description

Method for preparing a titanium catalyst component, titanium catalyst component, method for preparing a titanium catalyst and titanium catalyst

Technical field

The present invention relates to a method for preparing a titanium catalyst component, a titanium catalyst component, a method for preparing a titanium catalyst and a titanium catalyst .

The titanium catalyst on the basis of the titanium catalyst component according to the present invention is used for ethylene polymerization and copolymerization and can provide high catalytic activity to produce a polymer with a high bulk density, narrow particle size distribution and less fine particles.

Background of the invention

In recent years, studies relating to olefin polymerization catalysts have always been a highlight in the field of polyolefin research. The development of olefin polymerization catalysts having high catalytic activity, an excellent hydrogen response behavior, a homogeneous particle size distribution of the polymer and less fine particles is the objective pursued by scientific researchers. Many methods of using magnesium-containing Ti-based catalysts for olefin polymerization and copolymerization have been published. These catalysts provide high catalytic activity and generate the polymer with high bulk density, and they are useful for slurry polymerization and gas phase polymerization of ethylene .

Catalysts for producing polymers with high bulk density can be obtained using a magnesium-containing solution. For preparing such a magnesium-containing solution, a magnesium compound is reacted with an electron-donating compound. Electron-donating compounds include alcohols, amines, cyclic ethers or organic carboxylic acids. The magnesium-containing solution is generally prepared in the presence of a hydrocarbon solvent. Magnesium-carried catalysts can be prepared through the reaction of the magnesium-containing solution and a titanium halide compound (such as TiCl<i) .

US 3,642,746, US 4,336,360, US 4,330,649 and US 5,106,807 disclose alcohol-based methods for preparing a magnesium-containing solution.

US 4,477,639 and US 4,518,706 disclose a method of dissolving a magnesium compound by using tetrahydrofurane or another cyclic ether as the solvent.

Although a polymer with high bulk density can be produced by these catalysts, their catalytic activity is still insufficient. Moreover, a polymer produced with the above catalyst has a wide particle size distribution and a large quantity of fine particles, which can easily block the pipelines during the production process and impede a stable operation.

According to the preparation method of catalysts for ethylene polymerization and copolymerization disclosed in the Japanese patent JP 4951378 a slurry of a MgCl₂ • 6 C₂H₅OH adduct can be generated by the reaction between ground and crushed MgCl₂ and ethanol. A titanium-containing catalyst loaded by MgCl₂ can be obtained through esterification of the MgCl₂ • 6 C₂H₅OH adduct with diethyl aluminum chloride and a Ti-loading reaction with TiCl₄.

Although the preparation method of this catalyst is simple and the catalyst provides mild reaction conditions and a comparatively high activity for catalyzing ethylene polymerization, the MgCl₂ carrier cannot be dissolved in mineral oil and irregular flaky MgCl₂ particles exist in the slurry reaction system, which results in an irregular shape of the solid catalyst particles and inhomogeneous particle sizes. Therefore, the polymer also has an irregular shape and more fine particles, which easily generate static electricity and block the pipelines . Furthermore, a higher content of oligomers is generated in the solvent by the catalyst during polymerization, which easily block the pipelines and impede a post-treatment.

To overcome these problems, US 4,311,414 proposes a catalyst preparation method, which includes drying Mg(OH)₂ in the air, wherein the obtained catalyst can produce a polymer with narrow particle size distribution and improved average particle size.

US 3,953,414 and US 4,111,835 also disclose a catalyst preparation method, which includes drying hydrous MgCl₂ in the air, wherein the obtained catalyst can produce a polymer with a specific shape and a very large average particle size.

However, auxiliary devices, such as an air drier, are required for these methods. Moreover, the prepared catalyst provides lower catalytic activity and the obtained polymer contains very large particles, which makes the melting procedure of the polymer more difficult.

In addition, for use in the Unipol gas-phase fluidized bed process, which is the most typical gas-phase polymerization process of ethylene, the catalyst is usually prepared by providing silica gel having a large particle size with active components (Ti and Mg) . Because the shape of the catalyst completely depends on the particle shape of the silica gel carrier, catalyst performance also depends on the particle size and the microporous structure of silica gel used to prepare the catalyst .

For example, according to the catalyst for gas-phase polymerization by a fluidized bed process disclosed in US 4,302,565, the average particle size of the silica gel used is generally 40 μm to 80 μm. An LLDPE film-type resin made by this catalyst can provide excellent processing and mechanical properties. In the commercial gas-phase fluidized bed device, ethylene polymerization activity of this catalyst is generally about 3500 g PE/g cat.

However, the activity will significantly lower due to a reduction of the residence time of the catalyst, in case it is used for the condensation technology of the gas-phase fluidized bed, which consequently increases the ash content of the obtained ethylene polymer, which affects its performance . Thus, improving the catalytic activity of this kind of catalyst is one of the critical factors for enhancing the quality of an ethylene polymer produced by such a catalyst. In addition, the form and particle size distribution of polymer particles are the major factors of affecting the stable operation of a gas-phase fluidized bed device. Thus, in addition to improving the catalytic activity, excellent polymer particle morphology, particle size distribution and less content of fine powders is the target for this kind of catalyst.

With respect to the catalyst carrier disclosed in US 4,302,565, it is difficult to control a uniform distribution of the active components on the catalyst carrier, because the active components of the catalyst are loaded on the catalyst carrier by the impregnation method, which results in a poor repeatability of the preparation procedure of catalyst. Thus, catalyst activity, particle morphology and particle size distribution of the obtained polymer are not satisfactory.

On the basis of the above active components of the catalyst, fumed SiO₂ is used as the filler and mixed with a mixture obtained by reacting a titanium compound, a magnesium compound and an electron donor compound according to US 4,376,062 and CN 1,493,599 A. The catalyst can be obtained by a spray drying method. For applying the catalyst in a gas-phase fluidized bed polymerization process of ethylene, the particle size and morphology of the obtained catalyst can be easily controlled, while the catalyst efficiency is also improved to some extent. However, the catalytic activity of the catalyst and the shape of the polymerization product are still unsatisfactory. Moreover, when this catalyst is applied in the copolymerization of ethylene and higher-level α-olefins (such as 1-hexene) , the content of hexane extracts is still high in the obtained polymer, which will reduce the final product performance of a PE (copolymer) resin.

The purpose of the present invention is to overcome the above disadvantages of the current technical methods and provide a catalyst for ethylene polymerization and copolymerization, in particular for ethylene gas-phase polymerization using a fluidized bed in a condensation state or a super-condensation state, with high catalytic activity and good hydrogen response behavior for ethylene polymerization and copolymerization, which can produce a polymer with high bulk density, narrow particle size distribution and less fine particles.

In order to achieve the above purpose, the present invention provides in one aspect a method for preparing a titanium catalyst component, comprising the steps of:

- reacting a magnesium halide with a solvent including an alcohol to obtain a homogeneous solution

- reacting at least one organic boron compound with the homogeneous solution

- reacting a titanium compound with the homogeneous solution.

The step of reacting a magnesium halide with a solvent in the method for preparing a titanium catalyst component according to the present invention is generally carried out at a reaction temperature of at least -25 ⁰C, preferably at a reaction temperature of -10 ⁰C to 200 ⁰C and more preferably at a reaction temperature of 0 ⁰C to 150 ⁰C. The reaction time in this step is in general 15 min to 5 h, preferably 30 min to 4 h.

According to a preferred embodiment of the method for preparing a titanium catalyst component, the magnesium halide is selected from the group consisting of magnesium dihalides, alkyl magnesium halides, alkoxy magnesium halides and aryloxy magnesium halides.

In particular, examples for the magnesium dihalides include MgCl₂, MgBr₂, MgF₂ and MgI₂. The alkyl magnesium halides include methyl magnesium halide, ethyl magnesium halide, propyl magnesium halide, butyl magnesium halide, isobutyl magnesium halide, hexyl magnesium halide and amyl magnesium halide . The alkoxy magnesium halides include methoxy magnesium halide, ethoxy magnesium halide, isopropoxy magnesium halide, butoxy magnesium halide and octyl magnesium halide. The aryloxy magnesium halides include phenoxy magnesium halide and methyl phenoxy magnesium halide. These magnesium halides can be used independently or two or more magnesium halides may be used in combination.

Moreover, the above magnesium halides can be effectively used with magnesium-containing metallic coordination compounds. For example, the following compounds can be used as magnesium-containing metallic coordination compounds: compounds obtained through reaction between a magnesium compound and a polysiloxane, including silane compounds of halogen, ether or alcohol; compounds obtained through the reaction between metallic magnesium and alcohol, phenol or ether in the presence of a halogenated silane, PCl₅ or thionyl chloride . Said magnesium compound can be a magnesium halide, in particular MgCl₂, or an alkyl magnesium chloride containing 1 to 10 carbon atoms, an alkoxy magnesium chloride containing 1 to 10 carbon atoms and an aryloxy magnesium chloride containing 6 to 20 carbon atoms.

According to a preferred embodiment of the method for preparing a titanium catalyst component, the organic boron compound is an organic boron compound without active hydrogen, in particular an organic boron compound having the general formula

R¹^yB (OR³) _z

wherein

R¹ and R² are independently a Ci-C₁₀ alkyl group, a Ci-Cio alkoxy group, a C₅-C₁₀ aryl group or halogen,

R³ is a Ci-Cio alkyl group, preferably a Ci to Ce alkyl group, an aryloxy group

0 < x < 3,

0 < y < 3,

0 < z < 3, and x + y + z = 3

Preferred boron compounds represented by the above general formula include at least one of methyldibutylborate, trimethylborate, triethylborate, tripropylborate, tributylborate, trioctylborate, phenyldiethylborate, triphenylborate, trimethylborane, triethylborane, methyl diethylborane, diethoxy methylborane, diethoxy ethylborane, dibutoxy ethylborane, dibutoxy butylborane, diphenoxy phenylborane, ethoxy diethylborane, ethoxy dibutylborane, phenoxy diphenylborane, chloro diethoxyborane, bromo diethoxyborane, chloro diphenoxyborane, dichloro ethoxyborane, dibromo ethoxyborane, dichloro butoxyborane, dichloro phenoxyborane and chloro ethylethoxyborane .

According to a further embodiment of the method for preparing a titanium catalyst component the organic boron compound is selected from at least one of methyldibutylborate, trimethylborate, triethylborate, tripropylborate, tributylborate, trioctylborate, phenyl diethylborate and triphenylborate .

According to a further preferred embodiment of the method for preparing a titanium catalyst component, the titanium compound has the general formula

Ti⁽OR⁾ ₃Xb

wherein

R is an aliphatic Ci-Cio alkyl, preferably a Ci-C₄ alkyl group or a C₅-Ci₀ aryl group, X is F, Cl, Br or I, a is 0, 1, 2 or 3, b is an integer of 1 to 4, and a + b is 3 or 4.

According to a further preferred embodiment of the method for preparing a titanium catalyst component, the titanium compound is selected from the group consisting of TiCl₃, TiCl₄, TiBr₄, TiI₄, Ti(OC₃H₇)Cl₃ and Ti(OC₄Hg)₂Cl₂-

The homogeneous magnesium halide solution (magnesium-containing solution) is prepared by reacting said magnesium halide with a solvent including an alcohol.

The alcohol used to prepare the magnesium-containing solution includes those containing 1 to 20 carbon atoms and halogenated derivatives thereof, such as methanol, ethanol, propanol, isopropanol, butanol, pentanol, hexanol, 2-methyl pentanol, 2-ethyl hexanol, heptanol, 2-ethyl heptanol, octanol, decanol, dodecanol, octadecanol, benzenecarbinol, phenylethanol, isopropyl benzenecarbinol and cumic alcohol. The alcohol is preferably selected from alcohols containing 1 to 12 carbon atoms .

According to a further preferred embodiment of the method for preparing a titanium catalyst component, the alcohol is selected from the group consisting of methanol, ethanol, propanol, isopropanol, butanol, pentanol, hexanol, 2-methyl pentanol, 2-ethyl hexanol, heptanol, 2-ethyl heptanol, octanol and decanol or a mixture of two or more thereof.

According to a further preferred embodiment of the method for preparing a titanium catalyst component, the solvent further includes a hydrocarbon solvent.

According to a further preferred embodiment of the method for preparing a titanium catalyst component, the hydrocarbon solvent is selected from the group consisting of aliphatic hydrocarbon H

solvents, alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents and halogenated hydrocarbon solvents.

Examples for an aliphatic hydrocarbon solvent include pentane, hexane, heptane, octane, decane and kerosene. Alicyclic hydrocarbon solvents include cyclobenzene, methyl cyclobenzene, cyclohexane and methyl cyclohexane. Aromatic hydrocarbon solvents include benzene, toluene, xylene and ethylbenzene . Halogenated hydrocarbon solvents include dichloropropane, dichloroethylene, trichloroethylene, CCI₄ and chlorobenzene .

The average particle size and the particle size distribution of the obtained catalyst depend on the type and amount of alcohol, the type of the magnesium halide and the ratio of magnesium halide/alcohol .

When said magnesium halide solution reacts with the titanium compound, the shape and size of the precipitated component of the solid titanium catalyst component mainly depend on the reaction conditions . In addition, the reaction with the titanium compound can be conducted once or several times .

To control the particle shape, the solid titanium catalyst component may be obtained through a reaction between said magnesium halide solution, the titanium compound and the organic boron compound at a low temperature. The initial temperature thereof is set preferably to -70 ⁰C to 70 °C, more preferably to -50 °C to 50 ⁰C. When the reaction begins after the contact, the temperature is slowly raised and maintained for 0.5 h to 5 h at 50 ⁰C to 150 ⁰C to provide a continuous and complete reaction. According to further preferred embodiments of the method for preparing a titanium catalyst component, the organic boron compound is added to the homogeneous solution before adding the titanium compound, or the organic boron compound is added to the homogeneous solution after adding the titanium compound.

According to a further preferred embodiment of the method for preparing a titanium catalyst component, an inorganic carrier is added together with the organic boron compound.

In case an inorganic carrier is added together with the organic boron compound to the homogeneous magnesium halide solution, a spherical titanium catalyst component is obtained which can provide a spherical titanium catalyst with a high activity, which is in particular suitable for gas-phase polymerization of ethylene .

Before using the inorganic carrier in the method for preparing a titanium catalyst component according to the present invention, it is preferred to subject the inorganic carrier to a baking dehydration treatment or to an activating treatment by an alkylation.

According to a further preferred embodiment of the method for preparing a titanium catalyst component, the inorganic carrier is selected from the group consisting of SiO₂, Al₂O₃ and mixtures thereof.

According to a further preferred embodiment of the method for preparing a titanium catalyst component, the inorganic carrier has a spherical shape and a particle size of 0.1 μm to 150 μm. According to a further preferred embodiment of the method for preparing a titanium catalyst component, the inorganic carrier is SiO₂ having a specific surface area of 80 m²/g to 300 m²/g.

In case the inorganic carrier is SiO₂ having a specific surface area of 80 m²/g to 300 m²/g, the loading amount of magnesium in the catalyst can be improved and therefore the loading amount of the catalytically active component for the catalyst can be improved. Furthermore, the use of this specific inorganic carrier prevents an irregular aggregation of MgCl₂ in the catalyst at a high Mg content and a resulting non-spherical shape of the corresponding catalyst particles.

According to a further preferred embodiment of the method for preparing a titanium catalyst component, 0.1 mol to 10.0 mol of the alcohol, 0.05 mol to 1.0 mol of the organic boron compound and 1.0 to 15.0 mol of the titanium compound are used based on 1 mol of the magnesium halide.

In case an inorganic carrier is used in the method for preparing a titanium catalyst component, 0.1 mol to 10.0 mol of the alcohol, 0.05 mol to 1.0 mol of the organic boron compound, 50 to 500 g of the inorganic carrier and 1.0 to 15.0 mol of the titanium compound are used based on 1 mol of the magnesium halide.

According to a further preferred embodiment of the method for preparing a titanium catalyst component, after adding the organic boron compound and the titanium compound an additional titanium compound selected from the group consisting of a titanium halide or an alkoxy titanium halide having a Ci-Cg alkoxy group is added. According to a further aspect the present invention provides a titanium catalyst component, obtainable by the method for preparing a titanium catalyst component according to the present invention .

In case the present titanium catalyst component is used as a basis for a corresponding titanium catalyst, it can provide a titanium catalyst having high catalytic activity to produce a polymer with a high bulk density, narrow particle size distribution and less fine particles in case the titanium catalyst is used for ethylene polymerization and copolymerization.

In order to be used for ethylene polymerization and copolymerization the titanium catalyst component according to the present invention must be activated, which means that it must be treated with sufficient activator compound to transform the Ti atoms in the titanium catalyst component to an active state, such that a titanium catalyst is obtained.

Therefore, in another aspect the present invention provides a method for preparing a titanium catalyst, comprising:

reacting the titanium catalyst component according to the present invention with an organic aluminum compound having the general formula

AlR_nX₃-H

wherein

R is hydrogen or a Ci-C_2O alkyl group, preferably a Ci -Ce alkyl group

X is F, Cl, Br or I, and

0 < n < 3.

According to a preferred embodiment of the method for preparing a titanium catalyst, the organic aluminum compound is selected from the group consisting of trialkyl aluminum compounds, dialkyl halogen aluminum compounds, and alkyldihalogen aluminum compounds, wherein each alkyl group contains 1 to 6 carbon atoms, like for example methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, neopentyl, isopentyl, hexyl and cyclohexyl.

In particular, the organic aluminum compound is selected from the group consisting of triethyl aluminum, triisobutyl aluminum, ethyl aluminum dichloride, diethyl aluminum chloride, ethyl aluminum sesquichloride and hydrogenated diisobutyl aluminum.

Before the actual polymerization, a pre-polymerization can be carried out with said titanium catalyst component and ethylene or an α-olefin. This pre-polymerization can be conducted at a low temperature in the presence of a hydrocarbon solvent (such as hexane) , the above titanium catalyst component, said organic aluminum compound (such as triethyl aluminum) and ethylene or an α-olefin at an appropriate pressure.

In another aspect the present invention provides a titanium catalyst, obtainable by the method for preparing a titanium catalyst according to the present invention.

According to a preferred embodiment of the titanium catalyst, the molar ratio between the organic aluminum compound and the solid titanium catalyst component is in a range of 10 to 1000, preferably in a range of 20 to 200.

In another aspect the present invention provides the use of a catalyst according to the present invention for ethylene polymerization and copolymerization .

The catalyst according to the present invention can be used for homopolymerization of ethylene or copolymerization of ethylene with other α-olefins, like for example propylene, 1-butene, 1-pentene, 1-hexene, 1-octene and 4-methyl-l-pentene . A gas-phase method, a slurry method and a solution method may be used in the polymerization process.

To ensure a high polymerization rate, the polymerization using a titanium catalyst according to the present invention should be conducted at a suitable temperature. Generally, the polymerization temperature is 20 ⁰C to 200 ⁰C, preferably 60 ⁰C to 95 ⁰C. During the polymerization process, the pressure of the monomer is preferably 1 atm to 100 atm, more preferably 2 atm to 50 atm.

The following Examples are given to illustrate the present invention and are not intended to limit its scope.

First embodiment

The first embodiment of the present invention illustrated by examples 1 to 10 relates to the preparation of a titanium catalyst component using a magnesium halide, an organic boron compound and a titanium compound, and to a polymerization using the corresponding titanium catalyst obtained from said titanium catalyst component.

Example 1

4.76g (50 mmol) anhydrous MgCl₂, 75 ml decane and 16.3 g (125 mmol) isooctanol are heated to 130 ⁰C for 3h to obtain a homogeneous solution. Then 15 mmol tributylborate are added to the homogeneous solution and it is agitated for 2 h at 50 ⁰C. The obtained homogeneous solution is then cooled to room temperature. The solution is dripped into 150 ml TiCl₄ (the temperature is maintained at 0⁰C) during 1 h, and the temperature of the mixture is maintained at 0 ⁰C for 1 h after dripping. After that the mixture is heated to 120 ⁰C for 2 h and the temperature is maintained for 2 h. The obtained solids are separated by heat filtration and the residue is washed with hexane and decane until no precipitated titanium compound is detected in the washing liquid. After drying, a solid titanium catalyst component is obtained.

Ethylene polymerization

After replacing the air in a 2 1 stainless reaction vessel by high-purity N₂, the vessel is charged with 1 1 hexane and 1.0 ml triethyl aluminum (1 M), and a suitable amount of the above prepared titanium catalyst component is added to the vessel using a syringe. The contents of the vessel are heated to 75 ⁰C and H₂ is fed into the vessel such that the pressure in the vessel reaches 0.28 MPa. Then ethylene is fed into the vessel such that the total pressure in the vessel reaches 0.73 MPa (gauge pressure) and a polymerization is carried out for 2 h at 8O⁰C. The results of the polymerization are shown in Table 1. Example 2

4.76g (50 mmol) anhydrous MgCl₂, 75 ml decane and 16.3 g (125 mmol) isooctanol are heated to 130 ⁰C for 3h to obtain a homogeneous solution. Then 15 mmol phenyldiethylborate are added to the homogeneous solution and it is agitated for 2 h at 50 ⁰C. The obtained homogeneous solution is then cooled to room temperature. The solution is dripped into 150 ml TiCl₄ (the temperature is maintained at 0⁰C) during 1 h, and the temperature of the mixture is maintained at 0 ⁰C for 1 h after dripping. After that the mixture is heated to 120 °C for 2 h and the temperature is maintained for 2 h. The obtained solids are separated by heat filtration and the residue is washed with hexane and decane until no precipitated titanium compound is detected in the washing liquid. After drying, a solid titanium catalyst component is obtained.

Ethylene polymerization

After replacing the air in a 2 1 stainless reaction vessel by high-purity N₂, the vessel is charged with 1 1 hexane and 1.0 ml triethyl aluminum (1 M), and a suitable amount of the above prepared titanium catalyst component is added to the vessel using a syringe. The contents of the vessel are heated to 75 ⁰C and H₂ is fed into the vessel such that the pressure in the vessel reaches 0.28 MPa. Then ethylene is fed into the vessel such that the total pressure in the vessel reaches 0.73 MPa (gauge pressure) and a polymerization is carried out for 2 h at 80⁰C. The results of the polymerization are shown in Table 1. Example 3

Example 3 is carried out in the same manner as Example 1, except that the addition amount of tributylborate is 20 mitiol. The results of the polymerization are shown in Table 1.

Example 4

Example 4 is carried out in the same manner as Example 1, except that the addition amount of tributylborate is 10 mmol. The results of the polymerization are shown in Table 1.

Example 5

Example 5 is carried out in the same manner as Example 1, except that the addition amount of decane is 50 ml. The results of the polymerization are shown in Table 1.

Example 6

4.76g (50 mmol) anhydrous MgCl₂, 75 ml decane and 16.3 g (125 mmol) isooctanol are heated to 130 ⁰C for 3h to obtain a homogeneous solution. Then 15 mmol triphenylborate are added to the homogeneous solution and it is agitated for 2 h at 50 ⁰C. The obtained homogeneous solution is then cooled to room temperature. The solution is dripped into 150 ml TiCl₄ (the temperature is maintained at 0 ⁰C) during 1 h and the temperature of the mixture is maintained at 0 ⁰C for 1 h after dripping. After that the mixture is heated to 120 ⁰C for 2 h and the temperature is maintained for 2 h. The obtained solids are separated by heat filtration and the residue is washed with hexane and decane until no precipitated titanium compound is detected in the washing liquid. After drying, a solid titanium catalyst component is obtained.

Ethylene polymerization

After replacing the air in a 2 1 stainless reaction vessel by high-purity N₂, the vessel is charged with 1 1 hexane and 1.0 ml triethyl aluminum (1 M), and a suitable amount of the above prepared titanium catalyst component is added to the vessel using a syringe. The contents of the vessel are heated to 75 ⁰C and H₂ is fed into the vessel such that the pressure in the vessel reaches 0.28 MPa. Then ethylene is fed into the vessel such that the total pressure in the vessel reaches 0.73 MPa (gauge pressure) and a polymerization is carried out for 2 h at 80⁰C. The results of the polymerization are shown in Table 1.

Example 7

4.76g (50 mmol) anhydrous MgCl₂, 75 ml decane and 16.3 g (125 mmol) isooctanol are heated to 130 ⁰C for 3h to obtain a homogeneous solution. Then 15 mmol methyldibutylborate are added to the homogeneous solution and it is agitated for 2 h at 50 ⁰C.

The obtained homogeneous solution is then cooled to room temperature. The solution is dripped into 150 ml TiCl₄ (the temperature is maintained at 0 °C) during 1 h and the temperature of the mixture is maintained at 0 ⁰C for 1 h after dripping. After that the mixture is heated to 120 °C for 2 h and the temperature is maintained for 2 h. The obtained solids are separated by heat filtration and the residue is washed with hexane and decane until no precipitated titanium compound is detected in the washing liquid. After drying, a solid titanium catalyst component is obtained. Ethylene polymerization

Example 8

Example 8 is carried out in the same manner as Example 1, except that the added boron compound is isopropyldibutylborate . The results of the polymerization are shown in Table 1.

Example 9

Example 9 is carried out in the same manner as Example 1, except that the added boron compound is triethylborate . The results of the polymerization are shown in Table 1.

Example 10

4.76g (50 mmol) anhydrous MgCl₂, 75 ml decane and 16.3 g (125 mmol) isooctanol are heated to 130 ⁰C for 3h to obtain a homogeneous solution. Then 15 mmol methyldibutylborate are added to the homogeneous solution and it is agitated for 2 h at 50 ⁰C. The obtained homogeneous solution is then cooled to room temperature. 150 ml TiCl4 are dripped into the above solution

(the temperature is maintained at 0 ⁰C) during 1 h and the temperature of the mixture is maintained at 0 ⁰C for 1 h after dripping. After that the mixture is heated to 120 ⁰C for 2 h and the temperature is maintained for 2 h. The obtained solids are separated by heat filtration and the residue is washed with hexane and decane until no precipitated titanium compound is detected in the washing liquid. After drying, a solid titanium catalyst component is obtained.

The ethylene polymerization is carried out in the same manner as in example 1. The results of the polymerization are shown in Table 1.

Table 1 Experimental Results

κ>

The above experimental results show that the titanium catalyst according to the present invention prepared from the titanium catalyst component according to the present invention can provide a polyethylene having a high bulk density, narrow particle size distribution and less fine particles.

Second embodiment

The second embodiment of the present invention illustrated by examples 11 to 18 and a comparative example relates to the preparation of a titanium catalyst component using a magnesium halide, an organic boron compound, an inorganic carrier and a titanium compound, and to a polymerization using the corresponding titanium catalyst obtained from said titanium catalyst component.

Example 11

4.76g (50mmol) anhydrous MgCl₂, 90 ml decane and 16.3 g (125 mitiol) isooctanol are heated to 130 °C for 3h to obtain a homogeneous solution. Then 15 mmol triethylborate are added to the homogeneous solution and it is agitated for 1 h at 50⁰C, whereupon

10 g silica gel (XPO2485, supplied by W. R. Grace & Co. , MD, USA) are introduced into the homogeneous solution. The obtained suspension is agitated for 1 h at 50 ⁰C and after that it is cooled to -10 ⁰C. 100 ml TiCl₄ are dripped into the obtained suspension under agitation, and the temperature of the suspension is maintained at -10 ⁰C for 1 h. After that the suspension is heated to 120⁰C for 3 h under agitation and the temperature is maintained for 2 h. The obtained solids are separated by heat filtration and the residue is washed with hexane and decane until no precipitated titanium compound is detected in the washing liquid. After drying, a solid titanium catalyst component having an excellent fluidity is obtained.

Ethylene polymerization

A 2 1 reaction vessel is heated to 80 ⁰C and the air in the vessel is replaced by dry N₂ and H₂ is blown into the vessel. The vessel is then charged with 1 1 hexane and 1.0 ml triethyl aluminum (1 M) , and a suitable amount of the above prepared titanium catalyst component using a syringe. The contents of the vessel are heated to 75⁰C and H₂ is fed into the vessel such that the pressure in the vessel reaches 0.28 MPa. Then ethylene is fed into the vessel such that the total pressure in the vessel reaches 1.03 MPa (gauge pressure) and a polymerization is carried out for 2 h at 80⁰C. The results of the polymerization are shown in Table 2.

Example 12

4.76g (50 mmol) anhydrous MgCl₂, 90 ml decane and 16.3 g (125 mmol) isooctanol are heated to 130 °C for 3h to obtain a homogeneous solution. Then 15 mmol triethylborate are added to the homogeneous solution and it is agitated for 1 h at 50 ⁰C, whereupon 12 g silica gel (XPO2485, supplied by W. R. Grace & Co. , MD, USA) are introduced into the homogeneous solution. The obtained suspension is agitated for 1 h at 50 °C and after that it is cooled to -10 ⁰C. 100 ml TiCl₄ are dripped into the obtained suspension under agitation, and the temperature of the suspension is maintained at -10⁰C for 1 h. 15 mmol triethylborate are added to the suspension and it is agitated for 1 h at -10 ⁰C. After that the suspension is heated to 120 ⁰C for 3 h under agitation and the temperature is maintained for 2 h. The obtained solids are separated by heat filtration and the residue is washed with hexane and decane until no precipitated titanium compound is detected in the washing liquid. After drying, a solid titanium catalyst component having an excellent fluidity is obtained.

The ethylene polymerization is carried out in the same manner as in example 11. The results of the polymerization are shown in Table 2.

Example 13

4.76g (50 mmol) anhydrous MgCl₂, 90 ml decane and 16.3 g (125 mmol) isooctanol are heated to 130 °C for 3h to obtain a homogeneous solution. Then 7.5 mmol triethylborate are added to the homogeneous solution and it is agitated for 1 h at 50 ⁰C, whereupon 12 g silica gel (XPO2485, supplied by W. R. Grace & Co. , MD, USA) are introduced into the homogeneous solution. The obtained suspension is agitated for 1 h at 50 ⁰C and after that it is cooled to -10 ⁰C. 100 ml TiCl₄ are dripped into the obtained suspension under agitation, and the temperature of the suspension is maintained at -10 ⁰C for 1 h. 7.5 mmol triethylborate are added to the suspension and it is agitated for 1 h at -10 ⁰C. After that the suspension is heated to 120 ⁰C for 3 h under agitation and the temperature is maintained for 2 h. The obtained solids are separated by heat filtration and the residue is washed with hexane and decane until no precipitated titanium compound is detected in the washing liquid. After drying, a solid titanium catalyst component having an excellent fluidity is obtained. The ethylene polymerization is carried out in the same manner as in example 11. The results of the polymerization are shown in Table 2.

Example 14

Example 14 is carried out in the same manner as Example 11, except that the organic boron compound is replaced by 15 mmol phenyldiethylborate .

Example 15

Example 15 is carried out in the same manner as Example 11, except that the organic boron compound is replaced by 15 mmol tributylborate .

Example 16

4.76g (50 mmol) anhydrous MgCl₂, 90 ml decane and 16.3 g (125 mmol) isooctanol are heated to 130 ⁰C for 3h to obtain a homogeneous solution. Then 7.5 mmol triethylborate are added to the homogeneous solution and it is agitated for 1 h at 50 ⁰C, whereupon 12 g silica gel (XPO2485, supplied by W. R. Grace & Co . , MD, USA) are introduced into the homogeneous solution. The obtained suspension is agitated for 1 h at 50 ⁰C and after that it is cooled to -10 ⁰C. 100 ml TiCl₄ are dripped into the obtained suspension under agitation, and the temperature of the suspension is maintained at -10 ⁰C for 1 h. After that the suspension is heated to 120 ⁰C for 3 h under agitation and the temperature is maintained for 2 h. The obtained solids are separated by heat filtration and the residue is washed with hexane and decane until no precipitated titanium compound is detected in the washing liquid. After drying, a solid titanium catalyst component having an excellent fluidity is obtained. According to an analysis the Ti content in the obtained titanium catalyst component is 3.0 %.

A quantity of the obtained titanium catalyst component is weighed and 60 ml hexane are added to disperse the titanium catalyst component. A precomplexing of the titanium catalyst component is carried out by adding AlEt₂Cl such that the Ti:Al ratio (mol:mol) is 10 and reacting the mixture for 0.5 h.

Ethylene polymerization

A 2 1 reaction vessel is heated to 80 ⁰C and the air in the vessel is replaced by dry N₂ and H₂ is blown into the vessel. The vessel is then charged with 1 1 hexane and 1.0 ml triethyl aluminum (1 M) , and 30 mg of the above prepared titanium catalyst subject to precomplexing. The contents of the vessel are heated to 75⁰C and H₂ is fed into the vessel such that the pressure in the vessel reaches 0.28 MPa. Then ethylene is fed into the vessel such that the total pressure in the vessel reaches 1.03 MPa (gauge pressure) and a polymerization is carried out for 2 h at 80⁰C. The results of the polymerization are shown in Table 2. Example 17

Example 17 is carried out in the same manner as Example 16, except that the precomplexing is carried out at room temperature by adding AlEt₂Cl such that the Ti:Al ratio (mol:mol) is 20.

The ethylene polymerization is carried out in the same manner as in example 16. The results of the polymerization are shown in Table 2.

Example 18

Example 18 is carried out in the same manner as Example 11, except that the amount of silica gel is 15 g.

Comparative example

A 250 ml three-neck flask, wherein the air has been replaced by N₂, is charged with 2.O g TiCl₃ ^• 1/3 AlCl₃, 4.6 g MgCl₂ and 115 ml tetrahydrofuran . The contents of the flask are heated to 65 ⁰C under agitation, reacted for 2 h at 65 ⁰C and after that the reaction mixture is cooled to 30 ⁰C. A 250 ml three-neck flask, wherein the air has been replaced by N₂, is charged with 6.9 g silica gel (TS-610, supplied by Cabot Corporation, MA, USA), the above reaction mixture is added to the flask and the temperature is maintained at 30⁰C for 2 h under agitation. The stirred mixture is then spray dried with a spray dryer under the following conditions: inlet temperature = 160 ⁰C, outlet temperature = 80⁰C . The solid titanium catalyst component obtained after spray drying had a content of Ti, Mg and THF of 2.41 %, 6.19 % and 33 %, respectively. Mineral oil is added to the titanium catalyst component, such that a mineral oil solution with a solid content of 30 % is obtained. AlEt₂Cl is added to the mineral oil solution and reacted with the titanium catalyst component for 20 min, whereupon Al (CeHi₃) ₃ is added. AlEt₂Cl and Al (CeHi₃) ₃ are added such that the molar ratio of THF: AlEt₂Cl : Al (C₆Hi₃) ₃ is 1:0.5:0.2.

Slurry polymerization of ethylene

A 2 1 reaction vessel is heated to 80 °C and the air in the vessel is replaced by dry N₂ and H₂ is blown into the vessel. The vessel is then simultaneously charged with 1 1 hexane, 1.0 ml triethyl aluminum (IM), and 30 mg of the above prepared titanium catalyst . The contents of the vessel are heated to 75⁰C and H₂ is fed into the vessel such that the pressure in the vessel reaches 0.28 MPa. Then ethylene is fed into the vessel such that the total pressure in the vessel reaches 1.03 MPa (gauge pressure) and a polymerization is carried out for 2 h at 80⁰C. The results of the polymerization are shown in Table 2.

Table 2 Experimental results

Ex. : Example

Comp. -Ex.: Comparative example The experimental results show that the titanium catalyst according to the present invention prepared from the titanium catalyst component according to the present invention can provide a polyethylene having a high bulk density, a very narrow particle size distribution and a very low amount of fine particles, which is particularly suitable for ethylene gas-phase polymerization using a fluidized bed in a condensation state or a super-condensation state.

Claims

1. A method for preparing a titanium catalyst component, comprising the steps of:

- reacting at least one organic boron compound with the homogeneous solution

- reacting a titanium compound with the homogeneous solution .

2. The method according to claim 1, wherein the magnesium halide is selected from the group consisting of magnesium dihalides, alkyl magnesium halides, alkoxy magnesium halides and aryloxy magnesium halides.

3. The method according to claim 1 or 2, wherein the organic boron compound has the general formula

R¹ _xR² _yB ( OR³ ) _z

wherein

R¹ and R² are independently a C₁-Ci₀ alkyl group, a Ci-Ci₀ al koxy group , a Cs-Ci₀ aryl group or halogen , R³ is a C₁-Ci₀ alkyl group, preferably a C₁ to C₆ alkyl group , a aryloxy group 0 < x < 3 , 0 < y < 3 , 0 < z < 3 , and x + y + z = 3 .

4. The method according to claim 3, wherein the organic boron compound is selected from at least one of methyl dibutyl borate, trimethyl borate, triethyl borate, tripropyl borate, tributyl borate, trioctyl borate, phenyl diethyl borate and triphenyl borate.

5. The method according to any one of claims 1 to 4, wherein the titanium compound has the general formula

Ti(OR)₃Xb

wherein

R is an aliphatic Ci-Cio alkyl group or a C5-C10 substituted or unsubstituted aryl group,

X is F, Cl, Br or I, a is 0, 1, 2 or 3, b is an integer of 1 to 4, and a + b is 3 or 4.

6. The method according to claim 5, wherein the titanium compound is selected from the group consisting of TiCl₃, TiCl₄, TiBr₄, TiI₄, Ti(OC₃H₇)Cl₃ and Ti (OC₄H₉) ₂C1₂ -

7. The method according to any one of claims 1 to 6, wherein the alcohol is selected from the group consisting of methanol, ethanol, propanol, isopropanol, butanol, pentanol, hexanol, 2-methyl pentanol, 2-ethyl hexanol, heptanol, 2-ethyl heptanol, octanol and decanol or a mixture of two or more thereof.

8. The method according to any one of claims 1 to 7, wherein the solvent further includes a hydrocarbon solvent.

9. The method according to claim 8, wherein the hydrocarbon solvent is selected from the group consisting of aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents and halogenated hydrocarbon solvents .

10. The method according to any one of claims 1 to 9, wherein the organic boron compound is added to the homogeneous solution before adding the titanium compound.

11. The method according to any one of claims 1 to 9, wherein the organic boron compound is added to the homogeneous solution after adding the titanium compound.

12. The method according to claim 10, wherein an inorganic carrier is added together with the organic boron compound.

13. The method according to claim 12, wherein the inorganic carrier is selected from the group consisting of SiO₂, Al₂O₃ and mixtures thereof.

14. The method according to claim 12 or 13, wherein the inorganic carrier has a spherical shape and a particle size of 0.1 μm to 150 μm.

15. The method according to claim 13 or 14, wherein the inorganic carrier iis SiO₂ having a specific surface area of 80 m²/g to 300 ru²/g.

16. The method according to any one of claims 1 to 11, wherein 0.1 mol to 10.0 mol of the alcohol, 0.05 mol to 1.0 mol of the organic boron compound and 1.0 to 15.0 mol of the titanium compound are used based on 1 mol of the magnesium halide.

17. The method according to any one of claims 12 to 15, wherein 0.1 mol to 10.0 mol of the alcohol, 0.05 mol to 1.0 mol of the organic boron compound, 50 to 500 g of the inorganic carrier and 1.0 to 15.0 mol of the titanium compound are used based on 1 mol of the magnesium halide.

18. The method according to any one of claims 1 to 17, wherein after adding the organic boron compound and the titanium compound an additional titanium compound selected from the group consisting of a titanium halide or an alkoxy titanium halide having a Ci-Cs alkoxy group is added.

19. A titanium catalyst component, obtainable by the method of any one of claims 1 to 18.

20. A method for preparing a titanium catalyst, comprising:

reacting a titanium catalyst component according to claim 19 with an organic aluminum compound having the general formula

AlR_nX₃-I₁

wherein

R is hydrogen or a C1-C20 alkyl group, X is F, Cl, Br or I, and 0 < n < 3.

21. The method according to claim 20, wherein the organic aluminum compound is selected from the group consisting of trialkyl aluminum compounds, dialkyl halogen aluminum compounds, and alkyldihalogen aluminum compounds, wherein each alkyl group contains 1 to 6 carbon atoms.

22. The method according to claim 21, wherein the organic aluminum compound is selected from the group consisting of triethyl aluminum, triisobutyl aluminum, ethyl aluminum dichloride, diethyl, aluminum chloride, ethyl aluminum sesquichloride and hydrogenated diisobutyl aluminum.

23. A titanium catalyst, obtainable by the method of any one of claims 20 to 22.

24. The catalyst according to claim 23, wherein the molar ratio of Al in the organic aluminum compound and Ti in the titanium catalyst compound is in a range of 10 to 1000.

25. Use of a catalyst according to claim 23 or 24 for ethylene polymerization and copolymerization .