KR100359931B1 - PREPARATION METHOD OF CATALYST FOR ETHYLENE HOMOPOLYMERIZATION OR ETHYLENE/α-OLEFIN COPOLYMERIZATION - Google Patents

Abstract

The present invention relates to a method for preparing a catalyst used for ethylene polymerization or copolymerization of ethylene and an α-olefin, and more particularly, to a method for preparing a supported catalyst comprising a transition metal on a magnesium-containing carrier.

The process of the present invention comprises an organomagnesium compound, carbon tetrachloride and Si (OEt) having a composition of MgPh ₂ .nMgCl ₂ .mR ₂ 0 where n = 0.37 to 0.7; m ≧ 2; R ₂ 0 = ether; Ph = phenyl ₄ is reacted with at least a molar ratio of carbon tetrachloride to the magnesium at a temperature of -20 ℃ ~80 ℃ 0.5 molar ratio comprising the following, the handling of the resulting support of titanium, according to the production process of the catalyst according to the present invention the magnesium carrier during manufacture By using Si (OEt) ₄ and carbon tetrachloride, it is possible to prepare a catalyst capable of making a polymer having a high apparent density by making the physical strength of polymer particles stronger than using carbon tetrachloride alone.

Description

Process for the preparation of catalyst for ethylene polymerization or ethylene / α-olefin copolymerization TECHNICAL FIELD

The present invention relates to a method for preparing a catalyst used for ethylene polymerization or copolymerization of ethylene and an α-olefin, and more particularly, to a method for preparing a supported catalyst including a transition metal on a magnesium-containing carrier. will be.

A carrier of Mg _m Cl _n C _p H _g (where m = 0.8-0.95; n = 1.60-1.90; p = 0.8-1.6; g = 1.4-3.4) by coating a transition metal compound on the carrier A method for producing a supported catalyst for ethylene polymerization containing a transition metal compound (TiCl ₄ , VCl ₄ , VOCl ₃ ) in a phase is known (SU 726702 A; SU 1400657 A). The carrier was prepared by reacting powdered magnesium and alkylchloride via a hydrocarbon in a molar ratio of RCl / Mg> 2.

The main problem of the catalyst prepared by the above known method is that the particle size composition of the catalyst powder having a wide particle size distribution (1 μm to 100 μm) is not controlled. In addition, the polymer powder obtained using the catalyst prepared by the above method also has a wide particle size distribution and a relatively low apparent density (0.22 g / cm 3 to 0.30 g / cm 3).

It is known that polymers having narrow particle size distributions and increased apparent densities can be prepared by improving the polymerization process.

For this purpose, a catalyst for polymerization having a narrow particle size distribution and morphology was used. However, in this case, since different polymerization techniques are applied according to the polymer application field, a catalyst having various average particle sizes is required. For example, in the case of slurry polymerization of ethylene, a catalyst of particles of 10 to 20 mu m is required, and in the gas phase polymerization, a catalyst of particles of 25 to 90 mu m is required.

In addition, the particle shape of the catalyst particles and the polymer must be maintained in the polymerization process separately from the particle size. In general, the catalyst for gas phase polymerization has a lower strength than the catalyst for slurry polymerization. Therefore, when gas phase catalysts are used in slurry polymerization conditions, the catalyst and polymers are destroyed. This is because the polymerization conditions are much harsher than the slurry polymerization, and the amount of polymer produced per unit time per unit time is three times higher in the case of slurry polymerization.

The polymerized polymer particles should be easy to control the particle size according to the stability of the polymerization process and the use of the product. In particular, it is known that polyethylene particles of high apparent density have a great influence on the particle transport by air of the particles in the post-polymerization process and the productivity of the extruder. If the strength of the carrier is so weak that the shape of the polymer particles is broken, the apparent density is reduced, affecting the transport and productivity of the particles.

Catalysts containing magnesium chloride as a carrier and having a narrow particle size distribution are selected from the group consisting of MgCl ₂ .3i-C ₈ H ₁₇ OH in a hydrocarbon solvent in the presence of an electron donor compound (e.g., ethylbenzoate, ethyl aniseate, etc.). It can be obtained by reaction of a compound with TiCl ₄ (Japanese Patent Application No. 59-53511). The catalyst produced by this method has particles of 5 μm to 15 μm in size and is highly active (35Kg-PE / g-Ti, h, C ₂ H ₄ atm) with a narrow range of controlled particle sizes and high apparent density. It is possible to prepare a polyethylene powder having a. However, the method has disadvantages such as application of low temperature (up to -20 ° C), excessive use of liquid TiCl ₄ as the reaction medium, and generation of large amounts of hydrogen chloride during the synthesis of the catalyst. In addition, according to the above method, a catalyst having a particle size of 15 µm or more cannot be prepared.

It is known to prepare a catalyst by reacting a magnesium-aluminum-alkyl compound (RMgR ₁ -NAlR ₃ -mD) with hydrogen chloride, and then reacting the obtained solid product (carrier) with titanium or vanadium halide (Germany Application 3636060). French Patent No. 2529207).

In this method, (n-Bu) Mg (i-Bu) or (n-Bu) Mg (Oct) dissolved in a hydrocarbon is used as the organomagnesium compound RMgR ', and tert-BuCl is used as hydrocarbon chloride. The main disadvantage of the catalyst produced by this method is that the catalytic activity is insufficient.

It is an object of the present invention to enable the preparation of polymers having a narrow range of controlled particle size distribution and improved physical strength, and ethylene polymerization or ethylene having high activity in both slurry and gas phase ethylene polymerization or ethylene / α-olefin copolymerization. It is to provide a method for preparing a catalyst useful for / α-olefin copolymerization.

1 shows the shape of the polymer particles of Example 1,

Figure 2 shows the shape of the polymer particles of Example 2,

Figure 3 shows the shape of the polymer particles of Comparative Example 1.

Method of producing the catalyst of the invention is MgPh ₂ .nMgCl ₂ .mR ₂ 0 (here, n = 0.37~0.7; m ≥2; R 2 0 = ether; Ph = phenyl), an organomagnesium compound, a chloride, carbon tetrachloride agent having a composition of And using Si (OEt) ₄ as a physical strength enhancer, reacting the molar ratio of carbon tetrachloride to magnesium at a temperature of −20 ° C. to 80 ° C. or higher at a molar ratio of at least 0.5, and then obtaining the carrier with a titanium compound or a vanadium compound. Or reacting the V / Mg molar ratio at 0.8 to 1.2 two to four times.

The present invention will be described in detail as follows.

In the process for the preparation of the catalyst of the invention, the organomagnesium compound, ie MgPh ₂ .nMgCl ₂ .mR ₂ 0 (where n = 0.37 to 0.7; m ≧ 2; R ₂ 0 = ether; Ph = phenyl) is ether, preferably It is preferably prepared by reacting powdered magnesium with chlorobenzene in the presence of dibutyl ether or di-isoamyl ether. It can also be used in the form of dissolved solutions in chlorobenzene, ethers, mixtures of chlorobenzenes and ethers, mixtures of chlorobenzenes and aliphatic or aromatic compounds.

The organic magnesium compound solution and carbon tetrachloride are reacted at a temperature of −20 ° C. to 80 ° C. with a molar ratio of carbon tetrachloride to 0.5 or more, thereby preparing a magnesium-containing carrier. The reason why the carbon tetrachloride is reacted at a molar ratio of 0.5 or more is to generate MgCl ₂ with a sufficient reaction, and below 0.5 molar ratio, unreacted substances remain, which causes problems in subsequent processes such as reaction with TiCl ₄ , resulting in lower activity. In this case, when the catalyst is prepared by mixing Si (OEt) ₄ with carbon tetrachloride, a carrier having increased physical strength may be obtained. In the present invention, the amount of Si (OEt) ₄ is preferably set to Si / Mg = 0.001 to 2 molar ratio. If the Si / Mg = less than 0.001 molar ratio, the effect of the present invention is inadequate, and if the Si / Mg = 2 molar ratio is exceeded, the properties of the particles are changed, the spherical carrier does not appear, resulting in a decrease in apparent density.

The suspension of the magnesium-containing carrier powder obtained in this step has a specific particle size and narrow particle size distribution, in particular, a narrow particle size distribution of 5 μm to 90 μm and a high apparent density. The size of the carrier and the catalyst particles is determined by the composition of the organomagnesium compound and the reaction conditions of the organomagnesium compound and carbon tetrachloride.

The magnesium-containing carrier obtained as described above mainly contains magnesium dichloride, ether, hydrocarbon complex and Si compound.

In the catalyst preparation method of the present invention, the carrier prepared as described above is a titanium compound or a vanadium compound in a hydrocarbon solvent at a molar ratio of Ti (V) /Mg=0.2 to 1.2, preferably 0.8 to 1.2. It is obtained by reacting at temperature. The catalyst may also be prepared by simultaneously treating a titanium compound and a vanadium compound.

In order to obtain a highly active catalyst in the present invention, the reaction with a titanium compound is preferably performed two or more times, preferably two to four times, with Ti / Mg = 1. This is to remove the ethoxy group of Si (OEt) ₄ present in the catalyst, which can be increased by two to four treatments. In view of the efficiency of the activity increase, it is particularly preferable that the reaction after the second time be carried out at 80 to 120 ° C or higher.

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 I, and a is 0, 1, 2 or 3. Preferred titanium compounds are titanium tetrachloride and titanium alkoxychlorides, examples of which include 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, and the like, and one or more compounds selected from the group consisting of these compounds may be used.

The vanadium compound used in the present invention is a compound having a maximum valence tetravalent or a vanadil group VO having a maximum valency trivalent. The vanadium compound has a structural formula of V (OR ⁴ ) _4-n X _n or VO (OR ⁴ ) _3-m X _m . R ⁴ is an aliphatic or aromatic hydrocarbon group having 1 to 14 carbon atoms or COR ⁵ (wherein R ⁵ is an aliphatic aromatic hydrocarbon group having 1 to 14 carbon atoms), X is Cl, Br, I, and n is 0 to 4 Is an integer or fraction, and m is an integer or fraction of 0 to 3. Examples of these compounds are vanadium tetrachloride, vanadil trichloride, vanadil tri-n-propoxide, vanadil triisopropoxide, vanadil tri-n-butoxide, vanadil tetra-n-butoxide and tetra -n-propoxide and the like, and one or more compounds selected from the group consisting of these compounds can be used.

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

For example, according to the present invention, a catalyst having a particle size of 5 to 10 μm and 10 to 15 μm useful for slurry ethylene polymerization can be prepared, and a particle size of 20 μm to 90 μm useful for gas phase ethylene polymerization. Catalysts can be prepared. When titanium chloride is used as the active component of the catalyst, polyethylene having a narrow molecular weight distribution is obtained.

The catalyst prepared according to the present invention is used for ethylene polymerization or copolymerization of ethylene with α-olefins. The catalyst of the present invention can be used with trialkyl aluminum (preferably tri-isobutylaluminum or triethylaluminum or trioctylaluminum) as cocatalyst. The polymerization is carried out by slurry polymerization at a temperature of from 50 ° C. to 100 ° C. in a hydrocarbon solvent (eg, nucleic acid, heptane), or gas phase polymerization at a temperature of 60 to 100 ° C. and a pressure of 2 to 40 atm in the absence of a hydrocarbon solvent. Performed by law. Hydrogen (5-50% by volume) is used as the 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.

Example 1

<A> Preparation of Organomagnesium Compound

393 g of magnesium powder (16.2 mol) in a 10 liter glass reactor equipped with a stirrer and a temperature controller in the presence of 4136 ml of dibutyl ether (24.2 mol) and 7.8 g of iodine dissolved in 57 ml butyl chloride as an activator And 5860 ml of chlorobenzene (56.3 mol) were reacted. The reaction proceeded with stirring for 10 hours under an inert gas atmosphere (nitrogen) at a temperature of 80 ~ 100 ℃. The reaction mixture was then stopped for 12 hours without stirring and the liquid phase was separated from the precipitate. The liquid phase is a solution in which an organic magnesium compound having a composition of MgPh _2.0 MgCl ₂ (C ₄ H ₉ ) ₂ O is dissolved in chlorobenzene (the concentration of Mg is 1.0 mol per liter).

<B> Carrier Synthesis

2500 ml of the solution (2.5 mol Mg) obtained in <A> was added to a reactor equipped with a stirrer, and 241 ml CCl ₄ (2.5 mol) and Si (OEt) ₄ 50.19 ml (0.23) mixed with 241 ml of toluene were added. Mole) was added into the reactor over 5 hours at a temperature of 50 ° C. (Si / Mg = 0.09). The reaction mixture was stirred for 1 hour at 70 ° C., then the solvent was removed and the precipitate was washed 5 times at 60 ° C. with 2000 ml of hexane. As a result, 252 g of powdered magnesium chloride carrier having a particle size of 20 µm was obtained while suspended in hexane.

<C> Preparation of Catalyst

275 mL of TiCl ₄ (Ti / Mg = 1.0) was added to the heptane suspension of the obtained organic magnesium carrier, and the reaction mixture was heated to 70 ° C., and then stirred for 1 hour to obtain a solid precipitate of 2000 mL n- at 60 ° C. Washed four times with hexane. After washing three times with 2000 mL of heptane, 275 mL of TiCl ₄ (Ti / Mg = 1.0) was injected again, and then maintained at 95 ° C. for 2 hours to prepare a catalyst including 2.0 wt% Ti.

<D> Polymerization of Ethylene

The polymerization of ethylene was carried out in a 2.0 L steel reactor equipped with a stirrer and a temperature control jacket. N-hexane (1000 ml) was used as a hydrocarbon solvent, and 3 mmol of Al (Et) ₃ was used as a promoter. The polymerization was carried out at a total pressure of 270 psi, the amount of hydrogen was kept constant at 300 ml, and carried out for 1 hour at a temperature of 80 ° C. The result data of ethylene polymerization are shown in Table 1.

A catalyst corresponding to 0.0113 g was used for the experiment, and the SPAN value calculated by the following equation from the powder analysis data was 0.6 or less.

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

Example 2

Under the same conditions as in <A> of Example 1, 5 ml of Si (OEt) ₄ (Si / Mg = 0.009) was used, and then a catalyst was prepared in the same manner as in Example 1. As for the particle | grains of the manufactured catalyst, the catalyst of 20 micrometers and 1.8 weight% of Ti loadings was obtained. The polymerization results are shown in Table 1.

Example 3

After washing three times with 2000 ml of heptane of Example 1, again 275 ml of TiCl ₄ (Ti / Mg = 1.0) and then the same method as in Example 1 except maintaining for 2 hours at 95 ℃ The catalyst was prepared. The polymerization results are shown in Table 1. The shape of the particles was the same but the activity was reduced to half of Example 1.

Comparative Example 1

The catalyst was prepared by following the same procedure as in Example 1 without injecting Si (OEt) ₄ under the same conditions as in Example <A>. As for the particle | grains of the manufactured catalyst, the catalyst of 20 micrometers and 1.8 weight% of Ti loadings was obtained.

Table 1 Polymerization Results

Si / Mg activation BD ¹⁾ g / cm 3 SPAN kg-PE / g-cat / h Example 1 0.09 9.1 0.42 0.50 Example 2 0.009 8.4 0.38 0.85 Example 3 0.09 4.3 0.41 0.50 Comparative Example 1 0 8.1 0.30 2.53

¹⁾ Bulk density of PE powder

As can be seen from the above, all of the activity is similar, but the apparent density (BD) decreases as the amount of Si / Mg decreases, it can be seen that the SPAN increased. It can be seen from FIG. 1 that the result is caused by the cracking of the polymer particles, and it was found that the cracking of the particles increases as the Si / Mg decreases.

As can be seen from the above, according to the method for preparing a catalyst of the present invention, the Si (OEt) ₄ and carbon tetrachloride are used together to prepare a magnesium carrier, so that the physical density of the polymer particles is stronger than that of the carbon tetrachloride alone. Catalysts capable of making high polymers can be prepared.

Claims (3)

MgPh ₂ .nMgCl ₂ .mR ₂ 0 (where n = 0.37 to 0.7; m ≧ 2; R ₂ 0 = ether; Ph = phenyl) is used to form an organomagnesium compound, carbon tetrachloride and Si (OEt) ₄ at -20 ° C. After reacting the molar ratio of carbon tetrachloride to magnesium at a temperature of ˜80 ° C. or higher at a molar ratio of 0.5 or more, the obtained carrier is reacted with a titanium compound or a vanadium compound at a Ti / Mg or V / Mg molar ratio of 0.8 to 1.2 2 to 4 times. Ethylene polymerization or method for producing a catalyst for copolymerization of ethylene and α-olefin. The method for producing a catalyst for ethylene polymerization or copolymerization of ethylene and α-olefin according to claim 1, wherein the amount of Si (OEt) ₄ is Si / Mg = 0.001 to 2 molar ratio. The method for preparing a catalyst for ethylene polymerization or copolymerization of ethylene and α-olefin according to claim 1, wherein the second and subsequent activation reaction with the titanium compound is performed at 80 to 120 ° C.