KR102656050B1 - Catalyst composition for polymerization of polyolefin, preparing method of catalyst for polymerization of polyolefin and process for polymerization of polyolefin using the same - Google Patents

Abstract

The present invention relates to a catalyst composition for polyolefin polymerization, a method for producing the catalyst, and a method for producing polyolefin using the same. More specifically, it relates to a magnesium compound solution in which a magnesium compound is dissolved in an alcohol solvent, and an internal electron donor represented by the following formula (1). A catalyst composition for polyolefin polymerization comprising a compound and a transition metal compound mixed in a hydrocarbon solvent, a method for producing a catalyst for polyolefin polymerization using the catalyst composition, and a method for producing an olefin-based monomer in the presence of a catalyst obtained by the catalyst composition. It relates to a method for producing polyolefin, including the step of polymerization.
[Formula 1]

In Formula 1, R ¹ , R ² , X and n are as defined in the specification.

Description

Catalyst composition for polyolefin polymerization, method for producing the catalyst, and method for producing polyolefin using the same

The present invention relates to a catalyst composition for polyolefin polymerization, a method for producing the catalyst, and a method for producing polyolefin using the same. More specifically, a method for producing a catalyst with low particle size and uniform size distribution and high polymerization activity using the same, It relates to a method of producing polyolefin for secondary battery separators with uniform and small particle size and easy control of molecular weight distribution, thereby improving moldability.

Polyethylene, which is widely used among polyolefins, is divided into low-density polyethylene and high-density polyethylene depending on density and performance. High-density polyethylene has excellent softening point, hardness, strength, and electrical insulation properties, and is mainly used in various containers, packaging films, fibers, pipes, packing, and insulating materials. In particular, high-density polyethylene has excellent mechanical properties, excellent chemical resistance and electrical insulation properties, and is inexpensive, so it is used as a material for secondary battery separators.

In addition to the recent trend of reducing the weight and miniaturization of electrochemical batteries to increase the portability of electronic devices, there is a tendency to require high-output, large-capacity batteries for use in electric vehicles, etc. Accordingly, in the case of a separator for secondary batteries, it is required to have a thin thickness and light weight, and at the same time, it is required to have excellent shape stability due to heat for the production of high-capacity batteries. In addition, recently, in terms of the characteristics of separators, not only permeability and heat shrinkage resistance, but also characteristics that affect battery life, such as cycle characteristics, and characteristics related to battery productivity, such as electrolyte injectability, are being considered important.

Among them, one of the processes that takes a considerable amount of time in battery production and is closely related to battery productivity is the winding process, and high-speed winding is currently being carried out to increase production speed. Therefore, research is needed to improve the tensile strength of the separator in order to prevent the problem of the separator breaking during high-speed winding and causing process defects. In order to increase tensile strength, it is necessary to manufacture high molecular weight polyolefin. When the molecular weight of polyolefin is high, processability decreases due to an increase in melt viscosity, resulting in low productivity and inconsistent quality of molded products. In order to improve the above shortcomings, it is necessary to develop a catalyst system that can easily control the density and molecular weight of the polymer.

Meanwhile, catalysts used to produce polyolefin can be divided into Ziegler-Natta catalysts, chromium-based catalysts, and metallocene catalysts depending on the type of central metal applied. Since these catalysts have different catalytic activity, hydrogen reactivity, molecular weight distribution, and reaction characteristics toward comonomers, they have been selectively used depending on the required characteristics of the manufacturing process and application product. Among these, the Ziegler-Natta catalyst containing magnesium has advantages over other catalysts in terms of high activity, operational stability, excellent physical properties, and economic efficiency, and is thus most widely used in the production of polyolefin polymers.

For example, U.S. Patent No. 6,225,428 describes a method of controlling the molecular weight and molecular weight distribution of a polymer using a metallocene catalyst supported on each carrier, but it has the disadvantage that the catalyst preparation method is complicated. U.S. Patent No. 9,644,050 describes a method of controlling the particle size of a catalyst using a Ziegler-Natta catalyst incorporating an internal electron donor, but the catalyst preparation method is complicated and there are limitations in obtaining polymer particles of low particle size. Korean Patent Application No. 2014-0140957 describes a method of controlling molecular weight distribution using a metallocene catalyst, but has the disadvantage of poor moldability due to the narrow molecular weight distribution when molding chlorinated polyethylene. Korean Patent Application No. 2015-0156838 describes a method for producing polyethylene using a Ziegler-Natta catalyst composition, but has the disadvantage that the polyethylene polymerization method for controlling molecular weight distribution is complicated.

Therefore, in order to solve the above shortcomings, if a technology for producing polyolefin with excellent activity, small particle size, and easy molecular weight distribution control through a simple process is provided, it is expected to be widely applied in related fields.

One aspect of the present invention is to provide a catalyst composition containing an internal electron donor compound and having a low particle size and uniform size distribution.

Another aspect of the present invention is to provide a method for producing a catalyst that has excellent process economy and has a low particle size and uniform size distribution, including an internal electron donor compound.

Another aspect of the present invention is to provide a method for producing polyolefin with high polymerization activity, uniform and small particle size, and easy control of molecular weight distribution, thereby improving moldability, using the catalyst of the present invention.

According to one aspect of the present invention, a catalyst composition for polyolefin polymerization is provided, comprising a magnesium compound solution in which a magnesium compound is dissolved in an alcohol solvent, an internal electron donor compound represented by the following formula (1), and a transition metal compound mixed in a hydrocarbon solvent. do.

[Formula 1]

In Formula 1, R ¹ , R ² , X and n are as defined in the specification.

According to another aspect of the invention, preparing a magnesium compound solution by dissolving a magnesium compound in an alcohol solvent; Adding an internal electron donor compound represented by the following formula (1) to the magnesium compound solution; and adding a transition metal compound mixed in a hydrocarbon solvent to a magnesium compound solution containing the internal electron donor compound. A method for producing a catalyst for polyolefin polymerization is provided.

[Formula 1]

In Formula 1, R ¹ , R ² , X and n are as defined in the specification.

According to another aspect of the present invention, a method for producing polyolefin is provided, comprising the step of polymerizing an olefin-based monomer in the presence of a catalyst prepared by the catalyst composition of the present invention.

According to the present invention, a polyolefin for a secondary battery separator that not only has high activity and apparent density in the polyolefin polymerization reaction, but also has improved mechanical properties and processability by easily controlling the particle size, distribution, and molecular weight distribution of the produced polyolefin, is manufactured. A catalyst composition for polyolefin polymerization, a method for producing the catalyst, and a method for producing polyolefin using the same can be obtained.

Hereinafter, preferred embodiments of the present invention will be described. However, the embodiments of the present invention may be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below.

The present invention relates to a catalyst composition for polyolefin polymerization that can produce a catalyst with low particle size and uniform size distribution, including an internal electron donor compound. More specifically, the catalyst composition for polyolefin polymerization of the present invention is a magnesium compound that is used as an alcohol solvent. It includes a magnesium compound solution dissolved in a solution, an internal electron donor compound represented by the following formula (1), and a transition metal compound mixed in a hydrocarbon solvent.

[Formula 1]

At this time, in Formula 1, R ¹ is hydrogen, a linear or branched (C ₁ -C ₂₀ )alkyl group, (C ₂ -C ₂₀ )alkenyl group, (C ₃ -C ₂₀ )cycloalkyl group, (C ₆ - C ₂₀ )aryl group, (C ₁ -C ₂₀ )alkylsilyl group, (C ₇ -C ₂₀ )alkylaryl group, or (C ₂ -C ₂₀ )alkyl group containing heteroatoms; R ² is hydrogen, or at least one hydrogen is substituted with a substituent selected from linear or branched (C ₁ -C ₂₀ )alkyl groups, and (C ₂ -C ₂₀ )alkenyl groups; X is halogen; n is 0 or an integer from 1 to 3.

In Formula 1, when R ¹ is a (C ₂ -C ₂₀ )alkyl group containing a heteroatom, the hetero atom may be O, N, or a combination thereof. Meanwhile, the halogen X may be fluorine, chlorine, bromine, or iodine.

In Formula 1, when R ² is hydrogen, it means when the cyclopentyl ring is unsubstituted, and R ² is a linear or branched (C ₁ -C ₂₀ ) alkyl group where at least one hydrogen is, and (C ₂ -C ₂₀ ) may be substituted with a substituent selected from an alkenyl group, and in this case, the number of substituents may be 1 to 4, for example, 1 to 2.

In a solution of a magnesium compound in which a magnesium compound is dissolved in an alcohol solvent, the magnesium compound can be mixed with alcohol and completely dissolved, and the alcohol causes the crystal structure of the magnesium compound to become sparse, so that the internal electron donor and transition metal compound that subsequently react are structural. to ensure stable coordination.

The magnesium compound is a non-reducing compound, and specific examples of the magnesium compound include magnesium halide, alkoxy magnesium, alkyl magnesium halide, alkoxy magnesium halide, or aryloxy magnesium halide. Specific examples include magnesium halides such as magnesium chloride, magnesium dichloride, magnesium bromide, magnesium fluoride, or magnesium iodide; Alkoxy magnesium halides such as methoxy magnesium chloride, ethoxy magnesium chloride, isopoxy magnesium chloride, butoxy magnesium chloride, or octoxy magnesium chloride; Allyloxymagnesium halides such as magnesium phenoxychloride; and alkoxymagnesium such as ethoxymagnesium, isopoxymagnesium, or butoxymagnesium, etc. may be used, and the use of magnesium halide is preferred as it increases the activity of the catalyst. In addition, it is preferable to use magnesium dichloride because it is structurally and coordinately stable and exhibits high activity with the transition metal compound, which is the main active metal.

The molar ratio of the magnesium compound and the alcohol in the magnesium compound solution may be 1:0.5 to 1:10, and preferably 1:1 to 1:5. If the molar ratio of alcohol to magnesium compound exceeds 10 mol compared to the magnesium compound, crystal formation by the transition metal compound is difficult and tends to inhibit activity, and if it is less than 0.5 mol, the magnesium compound does not dissolve, resulting in homogeneous magnesium. This is undesirable because a compound solution cannot be obtained.

Specific examples of the alcohol include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, n-pendanol, isopendanol, neopentanol, cyclopentanol, n-hexanol, n-heptanol, Aliphatic or cycloaliphatic alcohols such as n-octanol, decanol, dodecanol, 2-methylpentanol, 2-ethylbutanol, and 2-ethylhexanol; Aromatic alcohols such as cyclohexanol, methylcyclohexanol, and a-methylbenzyl alcohol may be used, and among these, aliphatic or cycloaliphatic alcohols or alcohols having 2 or more carbon atoms are preferred, for example, 2-ethyl 1- Hexanol can be used.

Meanwhile, the magnesium compound solution may further include a hydrocarbon solvent, and when a hydrocarbon solvent is added, it is preferable to obtain a homogeneous solution of the magnesium compound and alcohol while using a small amount of alcohol. The molar ratio of the magnesium compound and the hydrocarbon solvent in the step of preparing the magnesium compound solution may be 1:5 to 1:20.

At this time, the hydrocarbon solvent may be an aliphatic hydrocarbon, an alicyclic hydrocarbon, an aromatic hydrocarbon, or a combination thereof having 5 to 20 carbon atoms. For example, an aliphatic or cycloaliphatic hydrocarbon solvent having 6 to 17 carbon atoms is most preferred. More specific examples include aliphatic hydrocarbons such as hexane, heptane, octane, decane, dodecane, tetradecane, and mineral oil; Alicyclic hydrocarbons such as cyclic hexane, cyclic octane, methyl cyclic pentane, and methyl cyclic hexane; Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cumene can be mentioned.

The catalyst composition for polyolefin polymerization of the present invention further includes an internal electron donor compound represented by the following formula (1).

[Formula 1]

In Formula 1, R ¹ , R ² , X and n are as defined above.

The compound represented by Formula 1 is a carbonate-based compound that facilitates the conversion of magnesium and titanium residues into halides, allows the catalyst particle size to be adjusted by controlling the microcrystal size, and acts as an active site during halogenation and titanation. The formation of can be controlled, and the bulk density and molecular weight distribution can be adjusted.

Preferred compounds of formula 1 of the invention include, for example, 1-chloroethyl cyclopentyl carbonate, 1-chlorobutyl cyclopentyl carbonate, 1-chloropropyl cyclopentyl carbonate, 1-chloro-2-methylpropyl cyclopentyl carbonate, cyclopentyl It may be selected from the group consisting of 1-iodoethyl carbonate, cyclopentyl 1-iodobutyl carbonate, cyclopentyl 1-iodopropyl carbonate and cyclopentyl 1-iodo-2-methylpropyl carbonate.

Specific examples of the transition metal compound that can be used in the present invention include any transition metal compound known to be used as a Ziegler-Natta catalyst for polyethylene polymerization. In particular, preferred examples of the transition metal compound include compounds of the following formula (2).

[Formula 2]

MX _m (OR ³ ) _4-m

In Formula 2, M is selected from the group consisting of transition metal elements of groups IVB, VB ^and _VIB of the periodic _table , It is from 4 to 4.

Preferred examples of M include titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, and molybdenum. In addition, specific examples of the transition metal compound of Formula 2 include titanium tetrachloride, titanium tetrabromine, titanium tetraiodo, tetrabutoxy titanium, tetraethoxy titanium, diethoxy titanium dichloride, or ethoxy titanium trichloride. It is preferable to use titanium tetrachloride.

Meanwhile, the halogen X may be fluorine, chlorine, bromine, or iodine.

The transition metal compound may be dispersed in a hydrocarbon solvent. The hydrocarbon solvent may be selected from hydrocarbon solvents that can be used in the step of preparing the magnesium compound solution. Specific examples of the hydrocarbon solvent include aliphatic or cycloaliphatic (C ₅ -C ₂₀ ) hydrocarbons, and among them, aliphatic or cycloaliphatic (C ₆ -C ₁₇ ) hydrocarbon solvents are preferable. More specific examples include aliphatic hydrocarbons such as hexane, heptane, octane, decane, dodecane, tetradecane, and mineral oil; Alicyclic hydrocarbons such as cyclic hexane, cyclic octane, methyl cyclic pentane, and methyl cyclic hexane; Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cumene can be mentioned. In order for the particle size distribution of the produced solid catalyst to be uniform and the catalyst particle surface to be smooth and spherical, it is more preferable to use hexane.

The molar ratio of the magnesium compound and the transition metal compound of Formula 2 may be 1:1 to 1:10, and preferably 1:3 to 1:5. If an excessive amount of the transition metal compound of Formula 2 is included, there is a problem of not being able to control the reaction in the polymerization step due to high catalytic activity, and if it is less than the above range, a problem may occur in which the activity of the catalyst is too low.

Polyethylene can be polymerized in the presence of a catalyst prepared using the catalyst composition for polyethylene polymerization of the present invention, and the catalyst may further include a cocatalyst compound represented by Formula 3.

[Formula 3]

_AlR ^4p _{​ ​}

In Formula 3, R ⁴ may be a (C ₁ -C ₈ )alkyl group, X may be a halogen, and p may be an integer from 0 to 3.

The cocatalyst can increase catalytic activity by reducing transition metal compounds to form active sites. As such a cocatalyst, an alkyl aluminum compound represented by Formula 3 may be used without limitation, and specifically, triethyl aluminum, trimethyl aluminum, triisopropyl aluminum, trioctyl aluminum, diethylaluminum chloride, diethylaluminum bromide, Diethylaluminum iodide, diethylaluminum fluoride, ethyl aluminum dichloride, dimethyl aluminum chloride, methyl aluminum dichloride, or a combination thereof can be used.

The molar ratio of the cocatalyst to the magnesium compound may be 1:0.01 to 1:10, preferably 1:0.01 to 1:2. If the amount of co-catalyst used is too small, the molecular weight distribution of the produced polyethylene may appear narrow, and if the amount of co-catalyst used is too large, the catalytic activity may rapidly decrease.

Furthermore, according to the present invention, a method is provided that is performed in a simple process, has excellent process economics, and can produce a catalyst with low particle size and uniform size distribution, including an internal electron donor compound. In more detail, the polyolefin of the present invention is provided. The method for producing a polymerization catalyst includes dissolving a magnesium compound in an alcohol solvent to prepare a magnesium compound solution; Adding an internal electron donor compound represented by the following formula (1) to the magnesium compound solution; and adding a transition metal compound mixed in a hydrocarbon solvent to the magnesium compound solution containing the internal electron donor compound.

[Formula 1]

At this time, in Formula 1, R ¹ , R ² , X and n are as defined for the catalyst composition.

Meanwhile, in the method for producing the catalyst for polyolefin polymerization of the present invention, details related to the catalyst composition, such as specific components and component ratios, are the same as described for the catalyst composition.

In the step of preparing a magnesium compound solution by dissolving a magnesium compound in an alcohol solvent, the magnesium compound can be completely dissolved by mixing with alcohol, and the alcohol is an internal electron donor and transfer agent that subsequently reacts by loosening the crystal structure of the magnesium compound. It allows metal compounds to coordinate structurally and stably.

The molar ratio of the magnesium compound and the alcohol in the step of preparing the magnesium compound solution may be 1:0.5 to 1:10, and preferably 1:1 to 1:5. If the molar ratio of alcohol to magnesium compound exceeds 10 mol compared to the magnesium compound, crystal formation by the transition metal compound is difficult and tends to inhibit activity, and if it is less than 0.5 mol, the magnesium compound does not dissolve, resulting in homogeneous magnesium. This is undesirable because a compound solution cannot be obtained.

The step of preparing the magnesium compound solution can be performed at 60 to 150 °C. That is, the dissolution temperature for dissolving the magnesium compound in alcohol is preferably 80 to 140 ° C. If it is outside the above range, the magnesium compound does not dissolve well in alcohol or side reactions tend to increase.

Meanwhile, the step of preparing the magnesium compound solution may be performed in the presence of a hydrocarbon solvent, and when a hydrocarbon solvent is added, it is preferable to obtain a homogeneous solution of the magnesium compound and alcohol while using a small amount of alcohol. The molar ratio of the magnesium compound and the hydrocarbon solvent in the step of preparing the magnesium compound solution may be 1:5 to 1:20.

After preparing a homogeneous magnesium compound solution, the step of adding an internal electron donor compound represented by the following formula (1) to the magnesium compound solution is performed.

[Formula 1]

In Formula 1, R ¹ , R ² , X and n are as defined above.

The step of adding an internal electron donor compound represented by the following formula (1) to the magnesium compound solution can be performed at -10°C to 150°C, and the molar ratio is preferably 1:0.01 to 1:1 based on 1 mole of the magnesium compound. Preferably it may be 1:0.01 to 1:0.2, more preferably 1:0.01 to 1:0.15. If it is outside the above range, the activity of the catalyst may be lowered by interfering with the formation of transition metal particles to be supported on the manufactured catalyst.

After adding the internal electron donor compound represented by Formula 1 to the magnesium compound solution, a transition metal compound mixed in a hydrocarbon solvent is added to the magnesium compound solution containing the internal electron donor compound. By performing these steps, a solid-state catalyst can be prepared by adding a transition metal compound to the magnesium compound solution containing the internal electron donor compound.

The transition metal compound can be added by dispersing it in a hydrocarbon solvent. The hydrocarbon solvent may be selected from hydrocarbon solvents that can be used in the step of preparing the magnesium compound solution.

Polyethylene can be polymerized in the presence of a catalyst prepared using the method for producing a catalyst for polyethylene polymerization of the present invention, and further includes the step of activating the catalyst by adding a cocatalyst chemical represented by Formula 3 to the catalyst. can do.

[Formula 3]

_AlR ^4p _{​ ​}

In Formula 3, R ⁴ may be a (C ₁ -C ₈ )alkyl group, X may be a halogen, and p may be an integer from 0 to 3.

The cocatalyst can increase catalytic activity by reducing transition metal compounds to form active sites. As such a cocatalyst, an alkyl aluminum compound represented by Formula 3 may be used without limitation, and specifically, triethyl aluminum, trimethyl aluminum, triisopropyl aluminum, trioctyl aluminum, diethylaluminum chloride, diethylaluminum bromide, Diethylaluminum iodide, diethylaluminum fluoride, ethyl aluminum dichloride, dimethyl aluminum chloride, methyl aluminum dichloride, or a combination thereof can be used.

Additionally, the step of adding the co-catalyst compound to the catalyst may be performed at -30 to 100°C, and is particularly preferably 0 to 30°C. In addition, the contact time (reaction time) between the co-catalyst compound and the catalyst is preferably sufficient for 0.5 to 24 hours from the time the reaction occurs.

According to another aspect of the present invention, there is provided a method for producing polyolefin, comprising the step of polymerizing an olefin-based monomer in the presence of a catalyst for polyolefin polymerization prepared by the catalyst composition for polyolefin polymerization of the present invention as described above.

At this time, the polyolefin polymerization reaction may be carried out in a gas phase, liquid phase, or solution phase. When carrying out a polymerization reaction in the liquid phase, a hydrocarbon solvent can be used, and olefin itself can also be used as a solvent.

The polymerization temperature may be 0 to 200°C, with a preferred range of 30 to 150°C. If the polymerization temperature is less than 0°C, the catalyst activity is not good, and if it exceeds 200°C, it is undesirable because stereoregularity deteriorates. Polymerization pressure may be 1 to 100 atm, and is preferably 2 to 30 atm. If the polymerization pressure exceeds 100 atmospheres, it is undesirable from an industrial and economic standpoint. The polymerization reaction can be performed by any of batch, semi-continuous, or continuous methods.

On the other hand, the polyolefin produced using the solid catalyst according to the present invention can be supplemented with commonly added heat stabilizers, light stabilizers, flame retardants, carbon black, pigments, antioxidants, etc. In addition, the prepared polyolefin can be mixed with linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), high-density polyethylene (HDPE), and EP (ethylene/propylene) rubber.

In the present invention, the olefinic monomer is ethylene, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-itocene, norbornene, norbonadiene, ethylidene nobodene, phenylnobodene, vinylnobodene, dicyclopentadiene, 1,4-butadiene , 1,5-pentadiene, 1,6-hexadiene, styrene, alpha-methyl styrene, divinylbenzene, and 3-chloromethylstyrene.

As such, according to the present invention, a secondary battery separator not only has high activity and apparent density in the polyolefin polymerization reaction, but also has improved mechanical properties and processability by easily controlling the particle size, distribution, and molecular weight distribution of the polyolefin produced. A method for producing a catalyst for polyolefin polymerization capable of producing polyolefin and a method for producing polyolefin using the same can be obtained.

Hereinafter, the present invention will be described in more detail through specific examples. The following examples are merely examples to aid understanding of the present invention, and the scope of the present invention is not limited thereto.

Example

1. Preparation of catalyst and polymerization of polyethylene

Example 1

(1) Preparation of magnesium compound solution

Using a 2 liter pressure-resistant glass reactor equipped with a suction stirrer and an oil circulation heater, 90 g of magnesium chloride, 450 ml of decane, and 502 ml of ethylhexanol were added under a nitrogen atmosphere, and the mixture was heated at 300 rpm at 80°C. It was stirred at a rotation speed of . In order to completely dissolve the magnesium compound, the temperature was raised to 135°C, and when the mixture became a homogeneous solution, it was aged for 1 hour, 7.9 ml of 1-chloroethyl cyclopentyl carbonate was added, aged for an additional hour, and then aged in the reactor. A magnesium compound solution was prepared by lowering the temperature to 25°C.

(2) Generation of solid carrier and preparation of solid titanium catalyst

370 ml of titanium tetrachloride solution was added to 2900 ml of hexane as a solvent and aged for 30 minutes. Stirring was performed at a rotation speed of 700 rpm so that the hexane and titanium tetrachloride solutions could become a homogeneous solution. Here, 1500 ml of the magnesium compound solution prepared in (1) above was slowly added over 3 hours. At this time, the temperature of the reactant was maintained at -15°C. Once the input was completed, it was aged for 1 hour and then the temperature of the reactor was raised from -15°C to 20°C at a rate of 0.3°C/min.

When the temperature of the reactor reached 20°C, a maturation process was performed for 30 minutes, then the temperature of the reactor was raised to 75°C at a rate of 1°C/min, and the reactor was aged at 74°C for 2 hours. After cooling the temperature of the reactor to 40°C, stirring was stopped, precipitation was allowed, and the supernatant was removed and washed 5 times with 2 liters of hexane at 40°C. The final slurry was dried under vacuum for 30 minutes to obtain a catalyst.

(3) Polymerization of polyethylene

A 2 liter high pressure reactor heated to 125°C was refluxed with nitrogen for 1 hour to bring the high pressure reactor to a nitrogen atmosphere. The temperature of the reactor was cooled to 25°C under a nitrogen atmosphere, and 1 liter of purified hexane was injected. 2 mmol of triethylaluminum and 1 mg of the catalyst prepared in (2) above were added. After addition, while stirring at 250 rpm, when the temperature of the reactor reaches 70°C, 0.7 bar is added based on the partial pressure of hydrogen and the temperature is raised to 75°C. When the temperature reached 75°C, ethylene was injected and the entire pressure of the high pressure reactor was maintained at 7.1 bar to conduct polymerization for 2 hours. After completion of the reaction, the temperature of the reactor is cooled to room temperature, and the resulting polyethylene is filtered to remove remaining monomers. Polyethylene obtained through the above process was dried in a vacuum oven at 60°C for 2 hours, and then the yield, apparent density, and polymer particle size were measured.

Example 2

A catalyst was synthesized in the same manner as in Example 1, except that 3.9 ml of 1-chloroethyl cyclopentyl carbonate was added instead of 7.9 ml of 1-chloroethyl cyclopentyl carbonate in the preparation step of the magnesium compound solution. Polyethylene was manufactured.

Example 3

A catalyst was synthesized in the same manner as in Example 1, except that 15.7 ml of 1-chloroethyl cyclopentyl carbonate was added instead of 7.9 ml of 1-chloroethyl cyclopentyl carbonate in the preparation step of the magnesium compound solution. Polyethylene was manufactured.

Example 4

A catalyst was synthesized in the same manner as in Example 1, except that 23.6 ml of 1-chloroethyl cyclopentyl carbonate was added instead of 7.9 ml of 1-chloroethyl cyclopentyl carbonate in the preparation step of the magnesium compound solution. Polyethylene was manufactured.

Comparative Example 1

A catalyst was synthesized and polyethylene was prepared in the same manner as in Example 1, except that 6.8 ml of ethyl benzoate was added instead of 1-chloroethyl cyclopentyl carbonate in the preparation step of the magnesium compound solution.

Comparative Example 2

A catalyst was synthesized and polyethylene was prepared in the same manner as in Example 1, except that 38.9 ml of diisobutyl phthalate was added instead of 1-chloroethyl cyclopentyl carbonate in the preparation step of the magnesium compound solution.

Comparative Example 3

A catalyst was synthesized and polyethylene was prepared in the same manner as in Example 1, except that 10.5 ml of tetraethoxy silane was added instead of 1-chloroethyl cyclopentyl carbonate in the preparation step of the magnesium compound solution.

2. Measurement of physical properties of catalyst and polyethylene

The physical properties of the catalyst and polyethylene prepared in the above examples and comparative examples were measured by the following method and are shown in Table 1.

Experimental example: Measurement of catalyst and polyethylene properties

The particle shape of each product obtained in the above examples and comparative examples was observed using an electron microscope (SEM: Scanning Electron Microscope), and the particle size of the catalyst particles suspended in hexane was measured using a laser particle analyzer (Mastersizer : manufactured by Malvern Instruments) to obtain the cumulative distribution of particle size, and from this, the average particle diameter of the catalyst and particle size distribution index (uniformity) of the particles were determined as follows.

(One) Average particle size (D ₅₀ ): The size of particles corresponding to 50% of the cumulative weight

(2) Particle size distribution index (P): P = (D ₉₀ -D ₁₀ )/D ₅₀

(Here, D ₉₀ is the particle size corresponding to 90% of the cumulative weight, and D ₁₀ is the particle size corresponding to 10% of the cumulative weight)

Meanwhile, the polymer average particle size (APS), melt index (MI), molecular weight, and molecular weight distribution of polyethylene in Table 1 below were obtained as follows.

(3) Polymer average particle size (APS) measurement method: Powder APS (Average Particle Size) is measured using Seishin RPS-105M, a powder particle size analysis equipment, at 75, 125, 212, 300, 500, 710, 850, and 1000 ㎛. This was carried out by dropping 10 g of sample into a sieve consisting of a total of 8 steps, dispersing it evenly by vibration and hammering for 5 minutes, measuring the weight of the sample remaining in each sieve, and calculating the average value.

(4) Melt index (MI) measurement method: Measured at 190°C and 2.16 kg according to ASTM D1238, and expressed as g per 10 minutes.

(5) Molecular weight measurement method: Molecular weight distribution was measured by gel permeation chromatography performed according to the method according to DIN 55672 under the following conditions: Solvent: 1,2,4-trichlorobenzene, flow rate: 1 ml/min, temperature: 140 °C, calibration using PE standards.

(6) Molecular weight distribution: ratio of weight average molecular weight to number average molecular weight measured by gel permeation chromatography (Mw/Mn)

Catalyst average particle diameter (㎛) Catalyst particle size distribution index (Span) Polymer average particle size (APS, ㎛) MI _21.6kg
(dg/min) Molecular Weight
(g/mol) Molecular weight distribution Example 1 4.6 0.76 99 0.36 672,000 6.6 Example 2 5.3 0.72 108 0.30 680,000 6.8 Example 3 5.7 0.99 118 0.35 651,000 6.5 Example 4 6.1 1.02 135 0.34 660,000 6.0 Comparative Example 1 6.9 0.72 198 0.31 685,000 6.5 Comparative example 2 5.8 1.05 143 0.54 653,000 3.3 Comparative Example 3 9.5 0.83 182 0.69 647,000 5.8

The lower the span value, which measures the uniformity of a general catalyst, the better, and the lower the value, the more uniform the catalyst is. Therefore, the lower the span value, the improved operational stability during polyethylene polymerization and the ability to produce products with excellent physical properties.

As shown in Table 1, the span value of the catalyst prepared according to the example using the compound of the present invention as an internal electron donor was low to about 1 or less, confirming that the uniformity of the catalyst was excellent.

In addition, as can be seen in Table 1, according to the present invention, it is possible to manufacture a polyethylene catalyst with a small average particle diameter (㎛), so it is possible to provide a catalyst with a low particle size and uniform size distribution, and the polyethylene polymerized therefrom is Polyethylene for secondary battery separators with improved moldability can be manufactured because it has high polymerization activity, uniform and small particle size, and easy control of molecular weight distribution.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and variations are possible without departing from the technical spirit of the present invention as set forth in the claims. This will be self-evident to those with ordinary knowledge in the field.

Claims (8)

A catalyst composition for polyolefin polymerization comprising a magnesium compound solution in which a magnesium compound is dissolved in an alcohol solvent, an internal electron donor compound represented by the following formula (1), and a transition metal compound mixed in a hydrocarbon solvent:
[Formula 1]

(In Formula 1 above,
R ¹ is hydrogen, a linear or branched (C ₁ -C ₂₀ )alkyl group, (C ₂ -C ₂₀ )alkenyl group, (C ₃ -C ₂₀ )cycloalkyl group, (C ₆ -C ₂₀ )aryl group, ( C ₁ -C ₂₀ )alkylsilyl group, (C ₇ -C ₂₀ )alkylaryl group, or (C ₂ -C ₂₀ )alkyl group containing heteroatoms;
R ² is hydrogen, or at least one hydrogen is substituted with a substituent selected from linear or branched (C ₁ -C ₂₀ )alkyl groups, and (C ₂ -C ₂₀ )alkenyl groups;
X is halogen;
n is an integer from 0 to 3).
According to paragraph 1,
A catalyst composition for polyolefin polymerization, wherein the magnesium compound solution further includes a hydrocarbon solvent.
According to paragraph 2,
The hydrocarbon solvent is a (C ₅ -C ₂₀ ) aliphatic hydrocarbon, cycloaliphatic hydrocarbon, aromatic hydrocarbon, or a combination thereof, in the catalyst composition for polyolefin polymerization.
According to paragraph 1,
A catalyst composition for polyolefin polymerization, wherein the molar ratio of the magnesium compound and the internal electron donor compound represented by Formula 1 is 1:0.01 to 1:1.
According to paragraph 1,
A catalyst composition for polyolefin polymerization, wherein the molar ratio of the magnesium compound and the internal electron donor compound represented by Formula 1 is 1:0.01 to 1:0.1.
According to paragraph 1,
The transition metal compound is a catalyst composition for polyolefin polymerization comprising a compound of the following formula (2):
[Formula 2]
MX _m (OR ³ ) _{4 -m}
(In Formula 2, M is selected from the group consisting of transition metal elements of groups IVB, VB, and VIB of the periodic table,
X is halogen,
R ³ is a (C ₁ -C ₁₀ )alkyl group,
m is 0 to 4).
Preparing a magnesium compound solution by dissolving the magnesium compound in an alcohol solvent;
Adding an internal electron donor compound represented by the following formula (1) to the magnesium compound solution; and
Adding a transition metal compound mixed in a hydrocarbon solvent to the magnesium compound solution containing the internal electron donor compound;
Method for producing a catalyst for polyolefin polymerization comprising:
[Formula 1]

(In Formula 1 above,
R ¹ is hydrogen, a linear or branched (C ₁ -C ₂₀ )alkyl group, (C ₂ -C ₂₀ )alkenyl group, (C ₃ -C ₂₀ )cycloalkyl group, (C ₆ -C ₂₀ )aryl group, ( C ₁ -C ₂₀ )alkylsilyl group, (C ₇ -C ₂₀ )alkylaryl group, or (C ₂ -C ₂₀ )alkyl group containing heteroatoms;
R ² is hydrogen, or at least one hydrogen is substituted with a substituent selected from linear or branched (C ₁ -C ₂₀ )alkyl groups, and (C ₂ -C ₂₀ )alkenyl groups;
X is halogen;
n is an integer from 0 to 3).
Polymerizing an olefinic monomer in the presence of a catalyst prepared by the catalyst composition of any one of claims 1 to 6.
Method for producing polyolefin, including.