KR100240518B1 - Catalyst and process for polymerising ethylene and ethylene polymers produced therefrom - Google Patents

Abstract

The present invention relates to a highly active catalyst for ethylene polymerization prepared by reacting a magnesium halide, a silicon compound and a titanium compound, and a method for producing an ethylene polymer or an ethylene polymer using the catalyst.

The catalyst of the present invention has a silicon compound represented by the general formula Si (OR) ₄ (wherein R is an alkyl or aryl group having 1 to 20 carbon atoms) and an oxidation state in a mixture of magnesium halide, electron donor and inert organic solvent. It is prepared by reacting a tetravalent titanium compound.

The process for producing the ethylene polymer or ethylene polymer according to the invention is carried out using the catalyst of the invention as described above in the presence of an organometallic compound. According to the method of the present invention, it is possible to easily control the particle size of the polymer, have an extremely narrow particle size distribution, and obtain an ethylene polymer having a high apparent density or a copolymer of ethylene with an α-olefin having 3 to 12 carbon atoms.

Description

Catalyst for Ethylene Polymerization and Process for Preparing Ethylene Polymer and Ethylene / α-olefin Copolymer Using the Ethylene Polymerization Catalyst

The present invention relates to a catalyst for ethylene polymerization prepared by reacting a magnesium halide with a silicon compound and a titanium compound, and a method for preparing an ethylene polymer or a copolymer of ethylene with an α-olefin having 3 to 12 carbon atoms using the catalyst. .

Conventionally, as a solid catalyst for ethylene polymerization, a catalyst prepared by reacting an inorganic magnesium compound with a transition metal such as an excess of a titanium compound or a vanadium compound in the presence of an electron donor in an inert hydrocarbon solvent is known. SiCl ₄ is used for the purpose of solidifying the dissolved magnesium in the process of supporting the transition metal on the magnesium carrier.

However, when the polymerization is carried out using the catalyst prepared by the conventional method as described above, the resultant aggregate has a large amount of fine powder, a wide particle size distribution, and a low bulk density, resulting in productivity or processing. It causes serious defects in the handling of the city. In particular, polymers with high molecular weight and low melt index are difficult to pelletize, and thus, the polymers should be molded in a state produced in a polymerization reactor. When a large amount of fine powder is contained, dust is generated during the molding process of the polymer. The problem of deterioration arises. In addition, when the apparent density is low, there is a disadvantage in that the molding productivity is significantly reduced.

In order to solve this problem, US Pat. No. 4,311,414 employs a method of spray-drying magnesium hydroxide during polymerization, thereby improving the average particle size of the polymer and narrowing the particle size distribution. In addition, US Pat. Nos. 3,953,414 and 4,111,835 produced spherical resins having an average particle size of 750 microns by spraying and drying magnesium dichloride hydroxide during polymerization. However, such a manufacturing method has a disadvantage in that the manufacturing method is complicated and the activity is low because a reflection-dryer is required, and in particular, a resin of too large particles is generated, which does not uniformly melt during processing. .

The present invention is to solve the above problems, by using a silicon alkoxide compound as a particle control agent in the preparation of the catalyst, an ethylene polymer or ethylene and carbon number of a moderately large particle size, very narrow particle size distribution and very high apparent density Consisting of hydrocarbon radicals having from 3 to 12 A high activity solid catalyst capable of producing an -olefin copolymer and a method for producing an ethylene homopolymer and a copolymer using the same.

Hereinafter, the present invention will be described in detail.

The catalyst according to the invention is formulated in a mixture of magnesium halides, electron donor compounds and inert organic solvents of the general formula Si (OR) ₄ (wherein R is alkyl having 1 to 20 carbon atoms, particularly preferably 1 to 10 carbon atoms or And an aryl group) and a silicon compound having an oxidation state of tetravalent titanium compound. This process makes the most desirable catalyst for preparing polymers of suitable size and apparent density suitable for the purposes of the present invention.

Magnesium halides used in the present invention are anhydrides, for example, magnesium difluoride, magnesium dichloride, magnesium diiodide and the like, and magnesium dichloride is particularly preferable. The magnesium halide is dissolved in an inert gas, for example, an electron donor such as alcohol, carboxylic acid, aldehyde, ether, etc. and an inert organic solvent in the presence of nitrogen or helium to prepare a magnesium liquid mixture. As the electron donor used in this reaction, alcohols include linear aliphatic alcohols such as methanol, ethanol, isopropanol, hexanol, 2-ethylhexanol, octanol or decanol, cyclic alcohols such as cyclohexanol and benzyl alcohol, and aromatic alcohols. This includes. As the electron donor, carboxylic acid is preferably an organic carboxylic acid having 7 or more carbon atoms. Examples include those having 7 to 20 carbon atoms, such as caprylic acid, 2-ethylhexane, undisylene acid, and octanoic acid. Suitable aldehydes used as electron donors are those having 7 to 18 carbon atoms, such as capric aldehyde, 2-ethylhexyl aldehyde, and undecyl aldehyde. An example of an ether as the electron donor is tetrahydrofuran. The amount of the electron donor is preferably 0.1 to 10 mol per mol of the magnesium halide, and 4 to 6 mol is more preferable for preparing a catalyst having high activity and allowing the catalyst residue treatment to be omitted after polymerization. And inert organic solvents include hexane, heptane, kerosine, decane, benzene, toluene, xylene and chlorobenzene. The reaction temperature in the preparation of the magnesium liquid mixture is carried out in the range of 60 ℃ to 140 ℃, preferably at 80 ℃ to 120 ℃. And the reaction time in the production of magnesium liquid mixture is about 1 hour to 2 hours.

In the present invention, the silicon compound may be used as long as the compound may be represented by the general formula Si (OR) _{4. In} the general formula, R is preferably an alkyl group having 1 to 20 carbon atoms or an aryl group, and more preferably. Or an alkyl or aryl group having 1 to 10 carbon atoms. Examples of silicone compounds that can be used in the present invention include tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, tetrabutyl orthosilicate, tetraoctyl orthosilicate, tetrabenzyl orthosilicate, tetra Methylbenzyl orthosilicate and the like, particularly preferred is tetraethyl orthosilicate.

As the titanium compound used in the present invention, a _tetravalent titanium compound having the general formula Ti (OR) _m X _4-m is preferable, wherein R is a hydrocarbon group, an alkyl group having 1 to 10 carbon atoms, X is a halogen atom, and m is It is an integer of 0≤m≤4. Examples of such titanium compounds include titanium tetrahalides such as TiCl ₄ , TiBr ₄ and Til ₄ , Ti (OCH ₃ ) Cl ₃ , Ti (OC ₂ H ₅ ) Cl ₃ , Ti (OC ₄ H ₉ ) Cl ₃ , Ti ( Trihalogenated alkoxytitanium such as OC ₂ H ₅ ) Br ₃ and Ti (O (iC ₂ H ₅ )) Br ₃ , Ti (OCH ₃ ) ₂ Cl ₂ , Ti (OC ₂ H ₅ ) ₂ Cl ₂ , Ti (OC ₄ H _{9) 2} Cl ₂ and Ti (OC ₂ H _{5) 2} is halogenated alkoxy titanium such as _{Br 2, Ti (OCH 3)} 3 Cl, Ti (Oc 2 H 5) 3 Cl, Ti (OC 4 H 9) Tetraalkoxytitanium mixtures such as monohalogenated alkoxytitanium such as ₃ Cl and Ti (OC ₂ H ₅ ) ₃ Br, Ti (OCH ₃ ) ₄ , Ti (OC ₂ H ₅ ) ₄ , Ti (OC ₄ H ₉ ) ₄ have. Of these, titanium tetrahalide compounds are preferred, and titanium tetrachloride is particularly preferred.

The reaction of the magnesium compound with the silicon compound and the titanium compound is carried out at a temperature of -10 ° C to 50 ° C, preferably at 0 ° C to 30 ° C. The reaction time is about 1 hour to 2 hours. The amount of the silicon compound per mole of the magnesium compound is preferably 0.01 to 5 moles, and the amount of the titanium compound is preferably 1 to 20 moles, particularly preferably 0.1 to 2 moles of the silicon compound and 4 to 10 moles of the titanium compound. It's a mole.

The solid catalyst according to the present invention is prepared by a very simple method by reacting a silicon compound and a titanium compound in any order in a liquid mixture of magnesium halide, an electron donor and an inert organic solvent.

The solid catalyst of the present invention prepared by the above method is used for the preparation of ethylene polymers or the preparation of copolymers of α-olefins having 3 to 12 carbon atoms, preferably α-olefins having 3 to 6 carbon atoms and ethylene. Can be. The concentration of the α-olefin in the copolymer is not particularly limited, but the concentration of the α-olefin in the ethylene copolymerization reaction is generally not more than 40 mol%, preferably not more than 20 mol%. It is particularly preferable not to exceed 10 mol%, even more preferably not more than 5 mol%.

Ethylene homopolymerization or ethylene and α-oletil copolymerization reaction using the solid catalyst of the present invention may be carried out by slurry polymerization, solution polymerization or gas phase polymerization. In particular, slurry polymerization is preferred.

In the polymerization reaction, the solid catalyst of the present invention is contacted with an organometallic compound to obtain a copolymer with ethylene polymer or α-olefin composed of ethylene and a hydrocarbon radical having 3 to 12 carbon atoms.

The organometallic compound used in the polymerization can be used as long as it is an organometallic compound of Group IV to Group I on the Periodic Table of the Elements. In particular, organometallic aluminum is preferred. Specific examples include trialkyl aluminum such as triethyl aluminum and tributyl aluminum, trialkenyl aluminum such as triisoprenyl aluminum, alkyl aluminum sesquialoxide such as ethyl aluminum sesquiethoxide, and diethyl aluminum chloride. Dialkylaluminum halides, alkylaluminum dihalides such as ethylaluminum dihalide, and the like. Among the aluminum compounds exemplified above, it is preferable to use trialkylaluminum compounds, alkylaluminum halides and mixtures thereof. Although the amount of the organometallic compound is not particularly limited, it is generally used in the range of 0.1 to 1000 moles per mole of the titanium compound, and preliminarily partial activation of the catalyst prior to the polymerization reaction, and also polymerization without partial activation. You can also contact directly at.

Ethylene polymerization using the catalyst according to the invention or copolymerization of ethylene with an α-olefin composed of hydrocarbon radicals having 3 to 12 carbon atoms is generally carried out in the same manner as in the case of polymerization using a Ziegler type catalyst. Can be.

The polymerization is carried out in particular with or without an inert solvent and hydrogen, in the absence of absolute oxygen and moisture. As an inert solvent, an inert hydrocarbon solvent such as hexane, heptane or kerosene is used. Generally, a solid catalyst of 0.005 mmol to 0.05 mmol is used in the liquid phase, but the amount of catalyst can be changed as much as the capacity of the reactor and the activity of the catalyst. Therefore, the amount of catalyst used is not limited in the present invention.

The polymerization reaction is carried out at a reaction temperature of 20 ℃ to 120 ℃, preferably 40 ℃ to 100 ℃, the reaction pressure is 0kg / cm ² · G to 70kg / cm ² .G, preferably 0kg / cm ² · G To 60 kg / cm ² .G. Of course, in using the catalyst of the present invention, the reaction may be performed in two or more polymerization stages having different reaction conditions, that is, different hydrogen concentrations or different polymerization temperatures.

When the polymerization is carried out according to the method of the present invention using the solid catalyst of the present invention, it is possible to obtain a granular polymer having a very narrow particle size distribution and a very large apparent density. In particular, the average particle size of the polymer can be adjusted within the range of 100 μm to 300 μm by adjusting the molar ratio of silicon compound / magnesium halide.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples.

In the particle size analysis of the polymer prepared in Example, the sieve residual amount (% by weight) was measured according to JIS K0069 using seven types of sieves (SIEVE), such as 840 μm, 500 μm, 250 μm, 177 μm, 105 μm, 74 μm, and 44 μm. Span was calculated from the following equation.

Span = (D90-A-D10) / D50

D90: Particle size at 90% by weight

D50: Particle size at 50% by weight

D10: Particle size at 10% by weight

Example 1

Catalyst Preparation:

4.76 g (0.05 mol) of anhydrous magnesium chloride was suspended in 50 ml of decane in the presence of nitrogen, and 30 ml (0.2 mol) of 2-ethylhexyl alcohol were added. The mixture was gradually heated with stirring to react at 100 ° C. for 2 hours to prepare a colorless transparent homogeneous solution in which solid particles were completely dissolved. This solution did not produce a solid precipitate even at room temperature. 2.5 ml of Si (OC ₂ H ₅ ) ₄ and 40 ml of TiCl ₄ were continuously injected into the prepared colorless and transparent homogeneous solution at 0 ° C., and then the reaction temperature was raised to 50 ° C. and reacted with stirring for 1 hour. Cooling to give a mixture of red color. The mixture was washed once with 400 ml of hexane to remove unreacted free TiCl ₄ , and then 50 ml of decane and 10 ml of TiCl ₄ were successively injected. The reaction temperature was raised to 80 ° C., stirred for 1 hour, and then cooled to room temperature to inject 400 ml of hexane to remove unreacted free TiCl ₄ . Washing was repeated until unsupported free titanium was removed. The titanium content of the prepared solid catalyst was 5.2wt%.

Polymerization

In a 2-liter autoclave in the presence of nitrogen, 1 liter of hexane and 2 mmol of triethyl aluminum and 0.018 mmol-Ti of the solid catalyst prepared above were injected. The reaction temperature was 80 ° C., 4psig of hydrogen was added before the reaction, and ethylene was injected to maintain the internal input of the reactor at 70 psig. Under these conditions, polymerization was carried out for 2 hours to obtain 230 g of ethylene polymers. The catalytic activity was 12.8 kg-PE / mmol-Ti. The average particle size of the obtained ethylene copolymer was 110 µm and Span was 0.6. The apparent density was 0.41 g / ml, the melt index at 2.16 kg was 0.032 g / 10 min, and the density was 0.957 g / ml.

Example 2

The catalyst was prepared in the same manner as in Example 1 except that Si (OC ₂ H ₅ ) ₄ and TiCl ₄ were injected at a temperature of 25 ° C., and the titanium content of the prepared solid catalyst was 5.0 wt%. The polymerization reaction was also carried out in the same manner as in Example 1 to obtain 280 g of an ethylene polymer. Catalytic activity was 15.6 kg-PE / mmol-Ti. The average particle size of the obtained ethylene polymer was 200 µm, Span was 0.6, and the apparent density was 0.40 g / ml.

Example 3

The catalyst was manufactured in the same manner as in the catalyst production process of Example 1, except that Si (OC ₂ H ₅ ) ₄ was charged in an amount of 7.5 ml. The titanium content of the prepared solid catalyst was 5.3 wt%. The polymerization reaction was also carried out in the same manner as in Example 1 to obtain 160 g of an ethylene polymer. Catalytic activity was 8.9 kg-PE / mmol-Ti. The average particle size of the obtained ethylene polymer was 250 µm, Span was 0.6, and the apparent density was 0.41 g / ml.

Comparative Example 1

4.76 g (0.05 mol) of anhydrous magnesium chloride was suspended in 50 ml of decane in the presence of nitrogen, 30 ml (0.2 mol) of 2-ethylhexyl alcohol was added thereto, and the mixture was slowly heated to react at 100 ° C. for 2 hours to make a uniform solution. After the temperature was lowered to room temperature, 12 ml (0.1 mol) of SiCl ₄ was slowly added dropwise and reacted at 50 ° C. for 1 hour to form a carrier. After lowering the temperature to room temperature, 30 ml (0.27 mol) of TiCl ₄ was slowly added dropwise at 80 ° C. The catalyst was prepared by reacting for 2 hours. The prepared catalyst was washed with 100 ml of purified hexane until free titanium was removed, and then dried and stored. The titanium content of the prepared catalyst was 6.2 wt%. The polymerization process was carried out in the same manner as described in Example 1. The obtained ethylene polymer was 150 g and the catalytic activity was 8.3 kg-PE / mmol-Ti. The average particle size of the ethylene polymer was 350 μm, Span was 1.5, and the apparent density was 0.27 g / ml.

Example 4

Except that the injection amount of Si (OC ₂ H ₅ ) _{4 In} the preparation of the catalyst was carried out in the same manner as described in Example 1, the titanium content of the prepared solid catalyst was 5.2wt%. Except that 2psig of butene-1 was injected in the polymerization process, it carried out similarly to Example 1, and obtained 300g of ethylene copolymers. Catalytic activity was 16.7 kg-PE / mmol-Ti. The average particle size of the obtained ethylene copolymer was 230 µm and Span was 0.6. The apparent density was 0.37 g / ml, the melt index at 2.16 kg was 0.02 g / 10 min, and the density was 0.948 g / ml.

Example 5

230 g of ethylene copolymers were obtained in the same manner as described in Example 4 except that 2 psig of propylene was injected in the polymerization process. The catalytic activity was 12.8 kg-PE / mmol-Ti. The average particle size of the obtained copolymer was 230 µm and Span was 0.6. The apparent density was 0.40 g / ml, the melt index at 2.16 kg was 0.02 g / 10 min, and the density was 0.954 g / ml.

Example 6

Except for injecting Si (OC ₃ H ₇ ) ₄ in the catalyst manufacturing process was carried out in the same manner as described in Example 1. The titanium content of the prepared catalyst was 5.4 wt%, the ethylene polymer obtained was 200 g, and the catalytic activity was 11.1 kg-PE / mmol-Ti. The average particle size of the obtained ethylene polymer was 150 µm, Span was 0.7, and the apparent density was 0.38 g / ml.

Example 7

Except for injecting Si (OC ₄ H ₉ ) ₄ in the catalyst manufacturing process was carried out in the same manner as described in Example 1. The titanium content of the prepared catalyst was 5.3 wt%, the ethylene polymer obtained was 220 g, and the catalytic activity was 12.2 kg-PE / mmol-Ti. The average particle size of the obtained ethylene polymer was 160 µm, Span was 0.7, and the apparent density was 0.38 g / ml.

Claims (8)

A silicon alkoxide compound represented by general formula Si (OR) ₄ (wherein R is an alkyl group or an aryl group having 1 to 20 carbon atoms) and a general formula Ti (OR) in a mixture of magnesium halide and electron donor compound and inert organic solvent an ethylene polymerization, which is prepared by reacting a titanium compound represented by _m X _4-m , wherein R is an alkyl group having 1 to 10 carbon atoms, X is a halo atom, and m is 0 ≦ m ≦ 4. Ethylene and Solid catalyst for copolymerization with olefins. The solid catalyst of claim 1, wherein the electron donor compound is an alcohol, a carboxylic acid, an aldehyde or an ether. The solid catalyst according to claim 1, wherein the inert organic solvent is hexane, heptane, kerosine, decanebenzene, toluene, xylene or chlorobenzene. The solid catalyst according to claim 1, wherein the molar ratio of magnesium halide and silicon alkoxide compound is in the range of 1: 0.01-5. The solid catalyst according to claim 1, wherein the molar ratio of magnesium halide and titanium compound is in the range of 1: 1 to 20. The solid catalyst of claim 1, wherein the reaction temperature of the magnesium halide, the silicon alkoxide compound, and the titanium compound is in the range of -10 ° C to 50 ° C. The presence of a solid catalyst and the organometallic compound of Claim 1, reaction temperature 20 ℃ to 120 ℃, the reaction pressure of 70kg / cm ^2, ethylene polymers or ethylene with a carbon number of 3 to 12, characterized in that is carried out at G or less α -Production method of copolymer with olefin. 8. The method of claim 7, wherein the organometallic compound is an organoaluminum compound.