KR20000008918A - Process for preparing carrier catalyst for polymerization of ethylene and copolymerization of ethylene/alpha-olefin - Google Patents

Abstract

PURPOSE: A catalyst is prepared which has a narrow particle size of distribution and increased bulk density to give polymer and copolymer having below 4 of molecular weight distribution. CONSTITUTION: Organomagnesium compound and organic chlorine compound such as carbon tetrachloride having MgPh2.nMgCl2.mR2O(Ph is phenyl; n is 0.37- 0.7; m is more than 1; R2O is ether) are reacted at -20- 80 degree C in the mole ratio of more than 0.5. Obtained carrier containing magnesium is treated with silicon compound such as silicon alkoxy chloride having Si(OR)aX4-a(R is C1- C14 aliphatic or aromatic hydrocarbon or COR1; R1 is C1- C14 aliphatic of aromatic hydrocarbon; X is Cl, Br or I; a is 0- 4) and titanium compound such as titanium alkoxy chloride having Ti(OR)aX4-a(R is C1- C14 aliphatic or aromatic hydrocarbon or COR1; R1 is C1- C14 aliphatic or aromatic hydrocarbon; X is Cl, Br or I; a is 0- 3) to give the catalyst. The organomagnesium compound is prepared by the reaction of magnesium metal and chlorobenzene in the presence of dibutyl ether and diisoamyl ether.

Description

Process for preparing supported catalyst for ethylene polymerization and ethylene / α-olefin copolymerization

The present invention relates to a method for preparing a catalyst for use in ethylene polymerization and copolymerization of ethylene and α-olefin, and more particularly, a supported catalyst comprising a transition metal on a magnesium-containing carrier having a narrow particle size distribution. It relates to a method of manufacturing).

By a method of coating a transition metal compound on a carrier, that is, an organic having a composition of MgPh ₂ .nMgCl ₂ .mR ₂ O (where n = 0.37 to 0.7; m ≧ ₂ ; R ₂ O-ether; Ph-phenyl) After reacting a magnesium compound with an organic halide, a method for preparing a supported catalyst for ethylene polymerization and a copolymerization of ethylene and α-olefin containing a transition metal compound such as TiCl ₄ , VCl ₄ or VOCl ₃ on the obtained carrier is provided. It was developed by some of the inventors of the invention (Japanese Patent No. 330675/1995).

The catalyst prepared by the above known method, in particular, a catalyst prepared by coating TiCl ₄ on a carrier, has a wide molecular weight distribution even though the polymerization process is partially improved by preparing a polymer having a narrow particle size distribution and an increased apparent density. And there is a problem that has a high initial activity.

For polymers with narrow molecular weight distribution, especially linear low density polyethylene products produced by copolymerization of ethylene and α-olefins, narrow molecular weight distribution reduces the content of low molecular weight polymers that can be evicted by hexane in the product. It is known that it can be improved.

For this purpose, there is a need for a catalyst with a homogeneous active site capable of narrowing the molecular weight distribution of the polymer.

An object of the present invention is to enable the preparation of polymers having a narrow particle size distribution and increased apparent density, and ethylene polymerization and ethylene having a molecular weight distribution of 4 or less in ethylene polymerization and ethylene / α-olefin copolymerization by slurry and gas phase polymerization. It is to provide a method for preparing a useful catalyst that can produce a / α-olefin copolymer.

Figure 1 shows the molecular weight distribution of the ethylene polymer using the catalyst prepared in Examples and Comparative Examples of the present invention.

The catalyst preparation method of the present invention is obtained by reacting an organic magnesium compound MgPh ₂ .nMgCl ₂ .mR ₂ O (wherein Ph = phenyl; n = 0.37 to 0.7; m ≧ 1: R ₂ O = ether) with an organic chlorine compound. The carrier is characterized by treating with an organic silicon compound and an organic titanium compound.

The organomagnesium compound used in the preparation of the magnesium-containing carrier in the present invention is prepared by reacting powdered magnesium with chlorobenzene in the presence of at least one electron donor compound. At this time, the electron donor may include aliphatic ether and cyclic ether. Aliphatic ethers are those having the structure of R ² OR ³ wherein R ² and R ³ are the same or different alkyl radicals of 2 to 8 carbon atoms, preferably aliphatic ethers of 4 to 5 carbon atoms. The cyclic ether is a cyclic ether having 3 to 4 carbon atoms. Most preferred as electron donor is dibutyl or diisoamyl ether.

A magnesium-containing carrier is prepared by reacting the organomagnesium compound solution with at least one organochlorine compound, preferably carbon tetrachloride, at a molar ratio of organochlorine compound / Mg ≧ 0.5 at a temperature of −20 ° C. to 80 ° C. The suspension of the carrier powder containing magnesium obtained in this step has a specific particle size and narrow particle size distribution.

In the present invention, as the organochlorine compound, a compound of the general formula CR ′ _n Cl _(4-n) wherein R ′ is an alkyl radical having 1 to 12 carbon atoms (where n is an integer of 0 to 3 or less) is used. do.

The catalyst is a magnesium-containing carrier prepared as described above using a silicon compound and a titanium compound, Si / Ti = 0.1 to 2.0, preferably 0.5 to 1.0 molar ratio, Ti / Mg = 0.01 to 2.0, preferably 0.04 to 0.5 It is obtained by treating at a temperature of 20 ° C to 100 ° C, preferably 40 ° C to 80 ° C, in a hydrocarbon solvent at a molar ratio of.

If the Si / Ti molar ratio is less than 0.1, the effect of producing a polymer having a narrow molecular weight distribution is insignificant.

If the Ti / Mg molar ratio is higher than 2.0, it is generally necessary to remove the excess titanium compound which is not fixed on the support (carrier) in the catalyst washing process, and the high cost of waste treatment due to the toxicity and corrosion of the removed titanium compound There is difficulty holding it. In addition, when Ti / Mg is lower than 0.01, there is a problem that the activity is not sufficient.

The titanium compound used in the present invention has a structural formula of Ti (OR) _a X _4-a . R is an aliphatic or aromatic hydrocarbon group having 1 to 14 carbon atoms or COR 'wherein R' is an aliphatic or aromatic hydrocarbon group having 1 to 14 carbon atoms, X is Cl, Br or l, and a is 0, 1, 2 or 3. The titanium compound of the structural formula is made by mixing Ti (OR) ₄ and TiX ₄ , the mixing ratio is preferably 1: 1. Preferred titanium compounds are titanium alkoxychlorides, examples of which are TiCl ₄ , Ti (OC ₃ H ₇ ) ₂ Cl ₂ , Ti (OC ₃ H ₇ ) Cl ₃ , Ti (OC ₃ H ₇ ) ₃ Cl, Ti (OC ₄ H ₉ ) ₂ Cl ₂ , Ti (OC ₄ H ₉ ) Cl ₃ , Ti (OC ₄ H ₉ ) ₃ Cl.

The silicon compound used in the present invention has a structural formula of Si (OR) _a X _4-a . R is an aliphatic or aromatic hydrocarbon group having 1 to 14 carbon atoms or COR '(wherein R' is an aliphatic or aromatic hydrocarbon group having 1 to 14 carbon atoms), X is Cl, Br or I, and a is 0, 1, 2, 3 or 4. Preferred silicon compounds are silicon alkoxides, examples of which are Si (OC ₂ H ₅ ) ₄ , Si (OC ₂ H ₅ ) ₂ Cl ₂ , Si (OC ₂ H ₅ ) Cl ₃ , Si (OC ₂ H ₅ ) ₃ There is Cl.

The silicon compound and the titanium compound can be supported on the magnesium carrier in three ways as follows.

1. Method of supporting after mixing silicon compound and titanium compound before supporting.

2. A method of supporting a titanium compound after supporting the silicon compound.

3. A method of supporting a silicon compound after supporting the titanium compound.

Method 1 is preferable.

Before the magnesium-containing carrier is treated with the silicone compound and the titanium compound or after the treatment, the organoaluminum compound can be treated with a molar ratio of Al / Ti of 0.1 to 2, if necessary.

Preferably, the molar ratio of Al / Ti is 0.5 to 1.5, and the treatment is performed at a temperature of 30 ° C to 80 ° C. The use of excess organoaluminum has the disadvantage that the carrier is broken down to produce fine particles. As the organoaluminum compound used herein, an organoalkyl aluminum or organoaluminum halogen compound having a structure of AIR ' _n X _(3-n) is used. Where R 'means an alkyl group containing from 1 to 16 carbon atoms, more preferably from 2 to 12 carbon atoms, X represents a halogen compound such as chlorine, bromine, n is an integer ranging from 0 to 3 or Fraction. Such organoaluminum compounds include triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, ethylaluminum chloride, methylaluminum chloride, ethylaluminum sesquibromide, isobutylaluminum sesquichloride, dimethylaluminum chloride and diethyl Aluminum chloride, diethylaluminum bromide, diethylaluminum iodide, dinormalpropylaluminum chloride, dinormalylaluminum chloride, diisobutylaluminum chloride, dinomaloctylaluminum iodide, methylaluminum dichloride, ethylaluminum dichloride , Isobutyl aluminum dichloride, normal butyl aluminum dichloride and the like. Dual advantageous organoaluminum compounds are selected from dialkylaluminum chlorides or from ethylaluminum sesquichlorides.

In the catalyst preparation method of the present invention, in the step of producing a magnesium-containing carrier, the organomagnesium compound complex [MgPh ₂ .nMgCl ₂ .mR ₂ O] is chlorobenzene, ether (R ₂ O) or a mixture of chlorobenzene and ether, chlorobenzene It is used in the form of a solution dissolved in a mixture of and aliphatic or aromatic compounds.

The organic magnesium compound in solution was chlorinated with an organic chlorine compound at a molar ratio of organic chlorine compound / Mg ≥ 0.5 at -20 ° C. to 80 ° C. in a hydrocarbon solvent to obtain a carrier in which powdered organic magnesium was suspended in a hydrocarbon solvent. Are manufactured. The carrier obtained by this method has a narrow particle size distribution. The size of the carrier and the catalyst particles can be controlled within the range of 5 ㎛ to 150 ㎛ by the composition of the organic magnesium compound and the reaction conditions of the organic magnesium compound and the organic chlorine compound.

The magnesium-containing carrier thus obtained mainly contains magnesium dichloride (80-90 wt%), ether (7-15 wt%) and hydrocarbon complex (1-5 wt%).

The catalyst is prepared by treating the carrier with a mixed solution of _a silicon compound (Si (OR) _a X _4-a ) and a titanium compound (Ti (OR) _a X _4-a ) in _a hydrocarbon solvent or separately.

The process of the present invention provides for the preparation of highly active catalysts having a narrow particle size distribution and various average particle sizes, which can be used for a variety of applications.

For example, according to the present invention, catalysts having particle sizes of 5 to 10 μm and 10 to 15 μm useful for slurry ethylene polymerization can be prepared, and also have particle sizes of 25 μm to 150 μm useful for gas phase ethylene polymerization. Catalysts can be prepared. When a mixture of a silicon compound and a titanium compound is used as the active ingredient of the catalyst, polyethylene having a relatively narrow molecular weight distribution is obtained rather than using only the titanium compound. The narrow molecular weight distribution (MWD) is characterized by a molecular weight distribution <6 measured by gel permeation chromatography, and the titanium supported catalyst mixed with the silicone compound according to the present invention is used to obtain polyethylene and polyethylene copolymers of 2.5 <MWD <4 It is suitable.

The catalyst according to the invention is used for ethylene polymerization or copolymerization of ethylene and α-olefins. The catalyst of the invention can be used together with one or more organoaluminum compounds, preferably trialkylaluminum as cocatalyst.

The organoaluminum compounds which can be used have a structure of AlR _n X _3-n . Wherein R is an alkyl radical having 1 to 12 carbon atoms, X is a hydrogen atom or a halogen atom such as chlorine or fluorine or an alkoxy radical having 1 to 12 carbon atoms, and n is an integer or fraction of 1 to 3. As examples, tri-isobutylaluminum, triethylaluminum, trimethylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, ethylaluminum sesquichloride or diethylaluminum chloride can be used.

The polymerization is carried out by slurry polymerization at a temperature of from 50 ° C. to 100 ° C. in a hydrocarbon solvent (eg hexane, heptane), or gas phase polymerization at a temperature of 60 to 120 ° C. and a pressure of 2 to 40 atm in the absence of a hydrocarbon solvent. Performed by law. Hydrogen (5-90% by volume) is used as molecular weight regulator of the polymer. Propylene, butene-1, hexene-1,4-methylpentene-1 and other α-olefins are useful for the copolymerization of ethylene with α-olefins.

Hereinafter, the present invention will be described in detail through examples. However, the following examples do not limit the content of the present invention.

Comparative Example 1

<A> Preparation of Organic Magnesium Compound

In a 1 L glass reactor equipped with a stirrer and a thermostat, 29.2 g of magnesium powder (1.2 mol) in the presence of 410 ml of dibutyl ether (2.4 mol) and 0.29 g of iodine dissolved in 4 ml butyl chloride as an activator And 330 ml of chlorobenzene (3.2 mol) were reacted. The reaction proceeded with stirring for 10 hours under an inert gas atmosphere (nitrogen, argon) at a temperature of 80-100 ° C. The reaction mixture was then left for 12 hours without stirring and the liquid phase was separated from the precipitate. Liquid phase MgPh ₂ .0.49MgCl _2. A solution of an organic magnesium compound having a composition of 2 (C ₄ H ₉ ) ₂ O dissolved in chlorobenzene (the concentration of Mg is 1.1 mol per liter).

<B> Carrier Synthesis

100 ml (0.11 mol Mg) of the solution obtained in <A> was added to a reactor equipped with a stirrer, and 10.6 ml CCl ₄ (0.11 mol CCl ₄ ) dissolved in 42 ml heptane was heated at a temperature of 20 ° C. for 1 hour. Over into the reactor. The reaction mixture was stirred at the same temperature for 60 minutes, then the solvent was removed and the precipitate was washed four times at 60 ° C. with 100 ml of n-hexane. As a result, 11.8 g of powdered organomagnesium carrier was obtained in a suspended state in n-hexane.

<C> Preparation of Catalyst

Titanium alkoxy chloride prepared by mixing 1.5 mL of TiCl ₄ and 3.8 mL of titanium propoxide (Ti (OC ₃ H ₇ ) ₄ ) to the n-hexane suspension of the obtained organic magnesium carrier to have a Ti / Mg molar ratio = 1. The reaction mixture was added and heated to 60 ° C., and then stirred for 2 hours to wash the solid precipitate obtained at 60 ° C. four times with 100 ml n-hexane. The average particle size of the catalyst was 55 μm.

<Polymerization>

The polymerization of ethylene was carried out in a 2 L steel reactor equipped with a stirrer and temperature control jacket. N-hexane (1000 mL) was used as the hydrocarbon solvent and 2 mmol of Al (Et) ₃ was used as the promoter. The polymerization was carried out for 1 hour at a temperature of 80 ° C. under ethylene pressure of 7.5 atm and hydrogen pressure of 4.5 atm.

A catalyst corresponding to 0.015 mmol Ti was taken for the experiment and the catalytic activity was 12.58 kg PE per gTi catalyst, per unit time, and per unit ethylene pressure. Polyethylene melt index (MI) was 6.53g / 10min at 2.16kg load and 190 ℃, and melt index was 25 at 21.6kg and 2.16kg. The apparent density of the polyethylene powder was 0.34 g / cm ³ and showed a narrow particle size distribution. From the powder analysis data, the SPAN value calculated by the following equation was less than 0.6. The ethylene polymerization results are shown in Table 1.

SPAN = (d90-d10) / d50, where d90, d50 and d10 mean polyethylene particle sizes such that the total particle contents are 90, 50 and 10 wt%, respectively.

Example 1

A mixture prepared by mixing 1.5 ml of TiCl ₄ and 3.0 ml of silicon ethoxide (Si (OC ₂ H ₅ ) ₄ ) with an n-hexane suspension of the organic magnesium carrier obtained in Comparative Example 1 was prepared, and a Ti / Mg molar ratio = 0.125, A catalyst was prepared in the same manner as in Comparative Example 1 except that the Si / Mg molar ratio was adjusted to be 0.55. Ethylene polymerization was carried out in the same manner as in Comparative Example 1. The ethylene polymerization results are shown in Table 1 and the molecular weight distribution is shown in FIG.

Example 2

Silicon ethoxide (Si (OC ₂ H ₅ ) ₄ ) was added to the catalyst obtained in Comparative Example 1, except that Si / Ti molar ratio = 1 to Ti contained in the catalyst prepared in Comparative Example 1 was added. The catalyst was prepared by the same method as 1. Ethylene polymerization was carried out in the same manner as in Example 1. The ethylene polymerization results are shown in Table 1 and the molecular weight distribution is shown in FIG.

Example 3

1-hexene copolymerization was carried out using the catalyst obtained in Example 2. The polymerization was carried out in the same manner as in Example 1 except that 150 cc of 1-hexene was used before the polymerization. As a result of polymerization, ethylene and 1-hexene copolymer having a density of 0.947 g / cc was prepared. The ethylene copolymerization results are shown in Table 1.

Table 1. Polymerization test results

Example activation Mw Mw / Mn BD Spanratio unit* One 15.47 191,800 2.9 0.33 <0.6 2 2.95 194,900 3.1 0.42 <0.6 3 15.95 194,900 2.9 0.38 <0.6 Comparative Example 1 12.58 158,700 4.9 0.34 <0.6

* Unit: kg-PE / gTi.ethylene 1 atm.hr

** Mn: number average molecular weight, Mw: weight average molecular weight, Mw / Mn: molecular weight distribution

BD: apparent density

According to the catalyst production method of the present invention, a highly active catalyst having a narrow particle size distribution and various average particle sizes is provided. When the polymerization is carried out using the catalyst obtained according to the method of the present invention, the produced polymer has a molecular weight distribution of 4 or less. It has a narrow molecular weight distribution of.

Claims (9)

MgPh ₂ .nMgCl ₂ .mR ₂ O (herein, Ph = phenyl, n = 0.37 to 0.7; m≥1; R ₂ 0-ether), an organic magnesium compound and an organic chlorine compound were prepared at -20 ° C to 80 ° C. Preparation of Supported Catalysts for Ethylene Polymerization and Copolymerization of Ethylene and α-olefin by Reaction with a Molar Ratio of Organic Chlorine Compound and Magnesium at Temperature of 0.5 or More, and then Treatment of the Magnesium-Containing Carrier with a Silicone Compound and a Titanium Compound Way. The method according to claim 1, wherein the organomagnesium compound is prepared by reaction of metal magnesium with chlorobenzene in the presence of dibutyl ether or di-isoamyl ether. The method of claim 1, wherein the organic chlorine compound is carbon tetrachloride. The silicone compound of claim 1 wherein the silicon compound is Si (OR) _a X _4-a wherein R is an aliphatic or aromatic hydrocarbon group having 1 to 14 carbon atoms, or R 'is an aliphatic or aromatic hydrocarbon group having 1 to 14 carbon atoms. And X is Cl, Br or l, and a is 0, 1, 2, 3 or 4). The method of claim 4 wherein the silicon compound is silicon alkoxychloride. The compound of claim 1, wherein the titanium compound is selected from Ti (OR) _a X _4-a , wherein R is an aliphatic or aromatic hydrocarbon group having 1 to 14 carbon atoms, or R ′ is an aliphatic or aromatic hydrocarbon group having 1 to 14 carbon atoms. And X is Cl, Br or I, and a is 0, 1, 2 or 3). The method of claim 6 wherein the titanium compound is titanium alkoxychloride. The method according to claim 1, wherein the molar ratio of Si / Ti is 0.1 to 2.0 and the molar ratio of Ti / Mg is 0.01 to 2.0 when the magnesium-containing carrier is treated with a silicon compound and a titanium compound. The method of claim 1, further comprising treating the magnesium-containing carrier with an aluminum compound before or after the treatment with the silicon compound and the titanium compound at a molar ratio of 0.1 to 2.