Process for Producing Ziegler-Natta Catalyst for Linear Low-Density Polyethylene Polymerization

Abstract

The present disclosure relates to a method for producing a Ziegler-Natta catalyst for linear low-density polyethylene (LLDPE) polymerization. Specifically, according to one embodiment, the method for producing a Ziegler-Natta catalyst for linear low-density polyethylene polymerization includes a step of mixing magnesium chloride with an excessive amount of alcohol to produce a magnesium chloride support containing a magnesium chloride-alcoholate. The method for producing a Ziegler-Natta catalyst according to one embodiment is easy to control the catalyst composition and can effectively produce linear low-density polyethylene with excellent copolymerization performance capable of realizing various physical properties.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a Ziegler-Natta catalyst for linear low-density polyethylene polymerization, and a method for manufacturing linear low-density polyethylene using the Ziegler-Natta catalyst thus manufactured.

Background Art

[0002] A Ziegler-Natta (Z / N) type polymerization catalyst is a catalyst for producing an olefin polymer, for example, an ethylene copolymer. Usually, a Ziegler-Natta catalyst contains a magnesium compound, an aluminum compound, a titanium compound, etc. supported on a specific support.

[0003] Since the shape and size of the polymer polymerized using a Ziegler-Natta catalyst are determined according to the catalyst used, it is important to manufacture a catalyst that can enhance productivity and produce a polymer with a uniform distribution.

[0004] Although various development works for the manufacture of Ziegler-Natta catalysts have been carried out, some methods have aspects that are not easy for mass production of catalysts, such as the manufacturing conditions being quite sensitive or a large amount of impurities or waste being formed. U.S. Patent No. 8003741 describes a manufacturing method in which a magnesium compound is dissolved in alcohol and then a titanium compound is added, but it has the demerits of a complicated manufacturing process and a large variety of substances used.

Summary of the Invention

Problems to be Solved by the Invention

[0005] One embodiment aims to provide a method for manufacturing a Ziegler-Natta catalyst for linear low-density polyethylene polymerization.

[0006] Another embodiment aims to provide a Ziegler-Natta catalyst for linear low-density polyethylene polymerization manufactured by the manufacturing method according to the above embodiment.

[0007] Another embodiment aims to provide a method for producing linear low-density polyethylene using a Ziegler-Natta catalyst for linear low-density polyethylene polymerization according to the above embodiment.

Means for Solving the Problems

[0008] One embodiment provides a method for producing a Ziegler-Natta catalyst for linear low-density polyethylene polymerization, which includes a step of sequentially adding and reacting a metal compound containing an alkylaluminum chloride and titanium (Ti) represented by the following Chemical Formula 2 to a magnesium chloride support containing a magnesium chloride-alcoholate represented by the following Chemical Formula 1. [Chemical Formula 1] MgCl 2 ·x(R 1 OH) In the above Chemical Formula 1, R 1 is a C 1-20 organic group, and x is from 0.01 to 3. [Chemical Formula 2] R 2 y AlCl 3-y In the above Chemical Formula 2, R 2 are each independently a C 1-10 alkyl or a C 3-10 cycloalkyl, and y is from 1 to 2.

[0009] Another embodiment provides a Ziegler-Natta catalyst for linear low-density polyethylene polymerization produced by the method for producing a Ziegler-Natta catalyst for linear low-density polyethylene polymerization according to the above embodiment.

[0010] Another embodiment provides a method for producing linear low-density polyethylene, which includes a step of contacting a monomer containing the Ziegler-Natta catalyst for linear low-density polyethylene polymerization according to the above embodiment and ethylene.

Effects of the Invention

[0011] The present disclosure relates to a method for manufacturing a Ziegler-Natta catalyst for linear low-density polyethylene (LLDPE) polymerization. Specifically, according to one embodiment, the method for manufacturing a Ziegler-Natta catalyst for linear low-density polyethylene polymerization includes a step of mixing magnesium chloride with an excessive amount of alcohol to produce a magnesium chloride support containing a magnesium chloride-alcoholate. The method for manufacturing a Ziegler-Natta catalyst according to one embodiment is easy to control the catalyst composition and can effectively manufacture linear low-density polyethylene with excellent copolymerization performance capable of realizing various physical properties.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0013] The embodiments described in this specification may be modified into various other forms, and the technology according to one embodiment is not limited to the embodiments described below. Furthermore, throughout the specification, stating that a certain component "includes" means that, unless otherwise stated to the contrary, it does not exclude other components but may further include other components.

[0014] The numerical ranges used in this specification include the lower limit value, the upper limit value, all values within that range, increments logically derived from the form and width of the defined range, all of the limited values, and all possible combinations of the upper and lower limits of numerically defined ranges limited to different forms. As an example, when the content of a composition is limited to 10% to 80% or 20% to 50%, numerical ranges of 10% to 50% or 50% to 80% should also be interpreted as being described in this specification. Unless otherwise specifically defined in this specification, values outside the numerical ranges that may occur due to experimental error or rounding of values are also included in the defined numerical ranges.

[0015] Hereinafter, unless otherwise specifically defined in this specification, "about" is considered to be a value within 30%, 25%, 20%, 15%, 10%, or 5% of the explicitly stated value

[0016] Hereinafter, in this specification, "alkyl" is defined as being able to mean both alkyl or cycloalkyl, and alkyl or cycloalkyl, even without a specific definition, can be interpreted to include derivatives or ordinary substituents (such as halogen, etc.) that can be easily modified by an ordinary technician who expects similar effects to be exhibited.

[0017] In the conventional method for producing a Ziegler-Natta catalyst, alcohol is added to magnesium chloride to form a carrier in which magnesium chloride and alcohol are combined by a reprecipitation method, and an excessive amount of titanium tetrachloride is utilized to remove the alcohol combined with magnesium chloride. However, with the use of an excessive amount of titanium, the production of the catalyst becomes complicated, the ratio of titanium supported on the carrier becomes non-uniform depending on the reaction, and it is difficult to reproduce the catalyst performance.

[0018] One embodiment provides a method for producing a Ziegler-Natta catalyst for linear low-density polyethylene polymerization, in which the reaction conditions are easy and the generation of impurities can be minimized. The production method according to one embodiment enables the production of a catalyst capable of supporting various transition metals on a carrier, and using the catalyst, it is possible to produce linear low-density polyethylene with high polymerization activity and excellent copolymerization performance.

[0019] One embodiment provides a method for producing a Ziegler-Natta catalyst for linear low-density polyethylene polymerization, which includes the step of sequentially adding and reacting a metal compound containing an alkylaluminum chloride and titanium (Ti) represented by the following Chemical Formula 2 to a magnesium chloride carrier containing a magnesium chloride-alcoholate (complex, compolex) represented by the following Chemical Formula 1.

[0020] [Chemical Formula 1] MgCl 2 ·x(R 1 OH)

[0021] In the above Chemical Formula 1, R 1 is a C 1-20 organic group, x is from 0.01 to 3.

[0022] [Chemical Formula 2] R 2 y AlCl 3-y In the above Chemical Formula 2, R 2 are each independently a C 1-10Alkyl or C 3-10 is cycloalkyl, y is from 1 to 2.

[0023] When polymerizing linear low-density polyethylene using a Ziegler-Natta catalyst produced by a production method according to an embodiment, linear low-density polyethylene can be produced with a significantly increased yield (amount obtained) and / or catalyst mileage. Further, since the comonomer reactivity of the catalyst is excellent, the linear low-density polyethylene produced by the catalyst can have excellent physical properties such as a higher ratio in the low-density region and a higher elongation ratio compared to commercially available linear low-density polyethylene produced by conventional techniques.

[0024] The magnesium chloride support according to an embodiment contains a magnesium chloride-alcoholate which is an adduct of magnesium chloride and alcohol. When alcohol is utilized for the production of the magnesium chloride support as in an embodiment, magnesium chloride may be transformed into magnesium chloride suitable as a support for a Ziegler-Natta catalyst. Alternatively, the performance of the catalyst can be improved by causing a lattice bond on the surface of the support. Further, the magnesium chloride support according to an embodiment may be a spherical support.

[0025] The magnesium chloride-alcoholate according to an embodiment may be produced by a method including: mixing MgCl 2 with R 1 OH to obtain a magnesium chloride-alcoholate solution; and depressurizing the magnesium chloride-alcoholate solution to obtain a solid magnesium chloride-alcoholate.

[0026] In one embodiment, the step of obtaining the solid magnesium chloride-alcoholate may include filtering the solid (magnesium chloride-alcoholate) precipitated by depressurizing the magnesium chloride-alcoholate solution, followed by washing with a saturated hydrocarbon solution (e.g., pentane), and then further including a step of vacuum drying. Further, it may further include a step of heating at a high temperature (about 70 °C to 150 °C, about 70 °C to 130 °C, about 80 °C to 120 °C, about 90 °C to 110 °C, about 110 °C) and drying under vacuum. The production method of the magnesium chloride-alcoholate according to one embodiment significantly improves the problems existing in the conventional reprecipitation method.

[0027] In one embodiment, in the mixing step of MgCl 2 (which may be, for example, anhydrous magnesium chloride) and R 1 OH (which may be, for example, anhydrous alcohol), it is preferable to add an excessive amount of alcohol R 1 OH. For example, in the mixing step, the molar ratio of magnesium chloride to alcohol may be 1:5 to 1:20, 1:5 to 1:15, 1:5 to 1:12, 1:6 to 1:10, 1:7 to 1:10, or about 1:8.

[0028] The production method according to one embodiment may further include a step of further adding the alkylaluminum chloride represented by Chemical Formula 2 (support activation step) after the step of adding and reacting the metal compound.

[0029] In one embodiment, the metal compound may further include a transition metal, for example, it may further include a Group IV or Group V metal. Specifically, the metal compound may further include one or more metals selected from the group consisting of Zr, Hf, V, Nb, and Ta. Here, the metal may be included in the form of chloride, alkoxy chloride, alkylate, etc., which is an example and is not necessarily limited thereto.

[0030] In one embodiment, the metal compound containing titanium (Ti) is TiX 4 or (R 3 O) z Ti(X) 4-z may also be included. Here, X is a halogen atom which is I, Br, Cl or F, and the R 3 are each independently a linear or branched C 1-10 alkyl, C 1-8 alkyl, C 2-6 alkyl or C 1-5 alkyl, and z is an integer from 1 to 4. Specific examples of the metal compound include TiCl 4 , TiBr 4 , TiI 4 , Ti(OBu) 4 , Ti(Oi-Pr) 4 , Ti(OEt) 4 , Ti(OEt) 2 (Cl) 2 , or Ti(OEt)(Cl) 3 and the like. However, this is only an example and is not necessarily limited thereto.

[0031] In one embodiment, the metal compound containing titanium (Ti) may be a mixed metal compound further containing a Group V metal compound. For example, the metal compound according to one embodiment may be a mixed metal compound of a metal compound containing titanium (TiCl 4 ) and a Group V metal compound containing a Group V metal (VOCl 3 ).

[0032] In one embodiment, the R 1may be, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a cyclopentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, a decanyl group, a dodecanyl group, a 2-methylpentyl group, a 2-ethylbutyl group, a 2-ethylhexyl group, a cyclohexyl group, a methylcyclohexyl group, a benzyl group, a methylbenzyl group, an isopropylbenzyl group, but this is only an example and is not necessarily limited thereto. In one embodiment, the alcohol may be methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, n-pentanol, isopentanol, neopentanol, cyclopentanol, n-hexanol, n-heptanol, n-octanol, decanol, dodecanol, 2-methylpentanol, 2-ethylbutanol, 2-ethylhexanol, cyclohexanol, methylcyclohexanol, benzyl alcohol, methylbenzyl alcohol, isopropylbenzyl, but this is only an example and is not necessarily limited thereto.

[0033] In one embodiment, x may be 5.0 or less, 4.0 or less, 3.0 or less, 0.5 to 5.0, 0.5 to 4.0, 0.5 to 3.0, 0.5 to 2.0, 0.8 to 2.0, or about 0.92 to 1.62, but is not necessarily limited thereto.

[0034] In one embodiment, the R 2 are each independently a straight-chain or branched-chain C 1-6 alkyl, C 1-5 alkyl, C 2-5 alkyl, -CH 3 、-CH 2 CH 3 、-CH 2 CH 2 CH 3 、-CH 2 CH 2 CH 2 C 3 、C 3-6 cycloalkyl, C 4-6Cycloalkyl or C 5-6 It may be cycloalkyl, but this is an example and is not necessarily limited thereto.

[0035] In one embodiment, the y may be, for example, 0, 1 / 2, 1, 3 / 2 or 2.

[0036] In one embodiment, the alkylaluminum chloride represented by Chemical Formula 2 is C 6 H 15 Al 2 C 3 (i.e., (C 2 H 3 ) 3 / 2 AlC 3 / 2 )(Ethyl aluminium sesquichloride), EtAlCl 2 (Ethyl aluminium dichloride), MeAlCl 2 (Methyl aluminium dichloride), PrAlCl 2 (Propyl aluminium dichloride) or BuAlCl 2 (Butyl aluminium dichloride), and one or more thereof may be used simultaneously or as a mixture. In one embodiment, the alkylaluminum chloride may be a monomer or a dimer.

[0037] In one embodiment, the alkylaluminum chloride represented by Chemical Formula 2 is used in an amount of 10 equivalents or more based on the number of moles of the metal compound, whereby a catalyst having more excellent activity can be produced. For example, the molar ratio of the metal compound to the alkylaluminum chloride represented by Chemical Formula 2 may be 1:10 to 1:50, 1:15 to 1:45, 1:20 to 1:40, 1:25 to 1:35, 1:28 to 1:32, or about 1:30. However, this is an example and is not necessarily limited thereto.

[0038] In one embodiment, the molar ratio of the metal compound to the magnesium chloride support may be 1:0.1 to 1:30, 1:1 to 1:30, 1:5 to 1:30, 1:8 to 1:30, 1:10 to 1:30, 1:5 to 1:20, 1:10 to 1:20, 1:12 to 1:18, or about 1:15. However, this is only an example and is not necessarily limited thereto.

[0039] In one embodiment, the magnesium chloride may have peaks at the following diffraction angles 2θ in an X-ray diffraction (XRD) pattern.

[0040] 7° ± 2.0° to 10° ± 2.0°, 31° ± 2.0°, 33° ± 2.0°

[0041] The magnesium chloride-alcoholate according to the above embodiment may have a broad peak within the range of the peak values. For example, the peaks can overlap at about 7.5° and 7.9°. The values of the diffraction angles can include error values within a range of about ±0.2°.

[0042] In one embodiment, the step of adding alkylaluminum chloride to the magnesium chloride support may include diluting the obtained high-purity support in a saturated hydrocarbon (e.g., heptane) solution to produce a slurry, and then adding alkylaluminum chloride diluted in a saturated hydrocarbon (e.g., hexane) solution at room temperature (e.g., about 5°C to 25°C, about 10°C to 25°C, about 15°C to 25°C, about 18°C to 23°C).

[0043] In one embodiment, based on SEM analysis, the particle size of the magnesium chloride support may be about 5 μm to 80 μm, 10 μm to 80 μm, 20 μm to 60 μm, 10 μm to 50 μm, 20 μm to 40 μm, or about 40 μm (±20%).

[0044] Another embodiment provides a Ziegler-Natta catalyst for linear low-density polyethylene polymerization produced by a method for producing a Ziegler-Natta catalyst for linear low-density polyethylene polymerization according to an embodiment.

[0045] Still another embodiment provides a method for producing linear low-density polyethylene using the Ziegler-Natta catalyst for linear low-density polyethylene polymerization according to the above embodiment. Specifically, the method for producing the linear low-density polyethylene includes a step of contacting an olefin monomer containing ethylene with the Ziegler-Natta catalyst for linear low-density polyethylene polymerization according to an embodiment. In one embodiment, the olefin monomer may further include, for example, olefin monomers having 2 to 20 carbon atoms, 2 to 15 carbon atoms, or 4 to 10 carbon atoms. For example, it may be propylene, butene, pentene, hexene, heptene, octene, nonene, or decene, and specifically, it may be 1-propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, or 1-decene. However, this is only an example and is not necessarily limited to the above olefins.

[0046] In one embodiment, the linear low-density polyethylene may have a density of 0.91 g / mL to 0.94 g / mL, 0.912 g / mL to 0.938 g / mL, 0.915 g / mL to 0.935 g / mL, or 0.915 g / mL to 0.924 g / mL, but this is only an example and is not necessarily limited thereto. In one embodiment, the linear low-density polyethylene has a melt index (MI) measured at about 190 °C in accordance with ISO 1133:1997 or ASTM D1238:1999 of 1.0 g / 10 min to 5.0 g / 10 min, 1.0 g / 10 min to 4.0 g / 10 min, 1.0 g / 10 min to 3.5 g / 10 min, 1.0 g / 10 min to 3.0 g / 10 min, 1.0 g / 10 min to 2.5 g / 10 min, 1.5 g / 10 min to 2.5 g / 10 min, or 1.6 g / 10 min to 2.3 g / 10 min, but this is only an example and is not necessarily limited thereto.

[0047] Examples and experimental examples will be specifically illustrated and described below. However, the examples and experimental examples described below are only examples of a part of one embodiment, and the technology described in this specification is not limited thereto.

[0048] <Example 1> 20 g (0.21 mol) of anhydrous magnesium chloride was added to a 500 mL Schlenk flask, and 250 mL of heptane was added and stirred. After stirring to avoid aggregation and raising the temperature inside the reactor to about 70 °C to 80 °C, 77 g (1.7 mol) of absolute ethanol was gradually added dropwise with stirring to produce a magnesium chloride solution that was clearly dissolved. After magnesium chloride was dissolved, the pressure was gradually reduced to remove the ethanol inside the flask. Removal of ethanol caused magnesium chloride - ethanol adduct to begin to precipitate. After removal of ethanol similar to the initial usage amount, the precipitated magnesium chloride was filtered, washed more than twice with 100 mL of pentane, and vacuum dried to recover magnesium chloride - ethanol adduct. To remove the ethanol residue of the vacuum - dried magnesium chloride - ethanol adduct, it was heated to 100 °C and dried under reduced pressure to obtain a white powder magnesium chloride - ethanol adduct support (MgCl 2 ·n(EtOH)).

[0049] 190 mg (2.00 mmol) of magnesium chloride - ethanol adduct support was transferred to a transparent vial, 10 mL of heptane was added, and it was stirred well to disperse. Next, 0.54 mL (0.53 mmol) of a 1.0 M C 2 H 5 AlCl 2 hexane solution was added, and it was stirred at room temperature for 6 hours or more. Next, 1.1 mL (0.14 mmol) of 5 wt% TiCl 4 was gradually added dropwise and stirred for 12 hours or more. Further, 3.5 mL (3.50 mmol) of a 1.0 M C 2 H 5 AlCl 2 hexane solution was added dropwise and stirred for 12 hours or more to produce a pink magnesium chloride - supported catalyst (Ziegler - Natta catalyst) heptane slurry solution.

[0050] <Examples 2 and 3> The same method as in Example 1 was carried out, but metal compounds were used as shown in Table 1 below to produce a magnesium chloride - supported catalyst (Ziegler - Natta catalyst) heptane slurry solution.

[0051] <Comparative Example 1> After charging 33 mL (30 mmol) of a 0.9 M ethyl normal butyl magnesium heptane solution into a 500 mL flask, 127 mL of normal heptane was charged. Before introducing hydrogen chloride (HCl) gas, the internal temperature of the reactor was lowered to 0 °C and stirred using a magnetic stirrer. Anhydrous hydrogen chloride gas was introduced at a predetermined rate until no residual alkyl magnesium Grignard was confirmed to terminate the reaction, and a magnesium chloride supported heptane slurry solution with a concentration of 0.2 M was produced.

[0052] Next, 10 mL (2.00 mmol) of the previously prepared 0.2 M magnesium chloride supported solution was transferred to a transparent vial. As the alkyl aluminum chloride, 1.0 M C 2 H 5 AlCl 2 solution 0.52 mL (0.52 mmol) was added, and the mixture was stirred at room temperature for 6 hours or more. Next, 1.0 mL (0.13 mmol) of 5 wt% TiCl 4 was gradually added dropwise and stirred for 12 hours or more to produce a brown magnesium chloride supported catalyst (Ziegler-Natta catalyst) heptane slurry solution.

[0053] <Comparative Example 2> The same method as in Comparative Example 1 was carried out, and as a result, no catalyst was obtained when using alkyl aluminum chloride as shown in Table 1 below.

[0054]

Table 1

[0055] <Experimental Example 1> X-ray diffraction (XRD) analysis XRD analysis was carried out under the following equipment and analysis conditions to obtain the XRD spectrum of the magnesium chloride-ethanol adduct support produced in Example 1 (Figure 1).

[0056] Maker: Empyrean, X-ray Source Anode: Cu, Generator Voltage: 45 kV, Tube Current: 40 mA, Incidence Beam: BBHD, Divergence Slit: 1 / 4°, Anti-scatter Slit: 1°, Detector: PIXcel Detector, Sample Stage: Reflection Transmission Spinner

[0057] Figure 1 shows the XRD spectra of the conventional alpha (α) type MgCl 2 and the magnesium chloride-ethanol adduct (MgCl 2 ·n(EtOH), n = 0.92 - 1.62) produced in Example 1. For the magnesium chloride-ethanol adduct (MgCl 2 ·n(EtOH), n = 0.92 - 1.62), broad peaks (a peak where 7.5° and 7.9° overlap) were confirmed at diffraction angles (2θ) around approximately 7° - 10°.

[0058] <Experimental Example 2> Nuclear magnetic resonance (NMR) analysis NMR analysis was carried out under the following equipment and analysis conditions to obtain the XRD spectrum of the magnesium chloride-ethanol adduct support produced in Example 1.

[0059] Instrument Maker: Bruker, Power Hz: 500 MHz, NMR Solvent: THF-d8

[0060] First, to THF-d8, which is an NMR analysis solvent, toluene and the magnesium chloride-ethanol complex produced in Example 1 were stirred and completely dissolved. Then, 1 1H NMR was measured (Figure 2). After calculating the molar ratio of toluene to ethanol, the weight of the final ethanol was estimated. As a result, the molar ratio of magnesium chloride to ethanol in the magnesium chloride-ethanol complex was at the level of 1:0.92 to 1:1.62.

[0061] <Experimental Example 3> Scanning Electron Microscope (SEM) Analysis Under the following conditions, the magnesium chloride-ethanol complex produced in Example 1 was subjected to SEM analysis, and the results are shown in Figure 3.

[0062] Manufacturer: HITACHI, Model: SU8230, Mode: SE, Detector: SE, Acceleration Voltage: 5 kV, Current: 10 μA

[0063] Based on the SEM results, the particle size of the magnesium chloride-ethanol complex was measured. As a result, it was confirmed that particles with a particle size of about 40 μm ± 20% were mainly generated.

[0064] <Experimental Example 4> Polymerization of Linear Low-Density Polyethylene The autoclave reactor was filled with 0.5 L of a saturated hydrocarbon solvent (methylcyclohexane) in a stable anhydrous nitrogen state. 0.2 g (0.15 mol) of triethylaluminum and 100 mL (70 g, 0.7 mol) of 1-octene were added. After stirring while raising the temperature of the reactor to 180°C, ethylene was introduced into the reactor at 30 bar. The catalysts (1.7 μmol) produced in Examples 1 to 3 and Comparative Example 1 were diluted in a saturated hydrocarbon solvent (methylcyclohexane) (3 mL) and transferred to the catalyst port, and the catalyst port was pressurized with anhydrous nitrogen (50 bar). After the autoclave reactor was saturated with ethylene, under isothermal conditions at 180°C, the catalyst in the catalyst port was introduced into the reactor, and semi-batch polymerization with continuous supply of ethylene was carried out for 10 minutes. Next, the reactor was recovered at the discharge part, the solvent was dried, and a linear low-density copolymer (linear low-density polyethylene, LLDPE) was obtained. The obtained amount, catalyst mileage, melt index, and density of the obtained linear low-density polyethylene were measured and shown in Table 2 below.

[0065] Here, the catalyst mileage was defined as the value obtained by dividing the mass of the produced LLDPE by the mass of the catalyst.

[0066] The melt index was measured by testing at 190°C according to the ASTM D1238 standard, and the density was measured with a density gradient column.

[0067]

Table 2

[0068] Referring to Table 2 above, it can be confirmed that the obtained amount of the copolymer increases significantly when polymerizing using the catalyst produced in the examples compared to when polymerizing using the catalyst for linear low-density polyethylene polymerization produced in the comparative example.

[0069] <Experimental Example 5> Crystallization Elution Fractionation (CEF) Using the POLYMER-CHAR CRYTEX-42 equipment, tests were conducted using a TCB (trichlorobenzene) solution to analyze the physical properties of the polymers produced using the catalysts of the above Examples and Comparative Examples by Crystallization Elution Fractionation (CEF). Here, commercial products A (manufactured by Dow) and commercial product B (manufactured by SK) were prepared and used as a comparative group in the experiment. The results are shown in Figure 3.

[0070] From the above experiment, it was confirmed that for the polymer produced using the catalyst of the Example in the CEF spectrum, compared with the commercial products, the ratio in the high-density region (homopolymer) of about 80 °C to 100 °C was lower, and the ratio in the low-density region (copolymer) of about 50 °C to 80 °C was higher. Therefore, it can be known that using the catalyst of the Example, it is possible to effectively produce a low-density copolymer with a high elongation rate.

[0071] As described above, one embodiment has been described in detail with reference to the preferred examples and experimental examples. However, the scope of one embodiment is not limited to specific examples and should be interpreted according to the appended claims.

Claims

1. A method for producing a Ziegler-Natta catalyst for linear low-density polyethylene polymerization, comprising the step of sequentially adding and reacting a metal compound containing an alkylaluminum chloride represented by the following Chemical Formula 2 and titanium (Ti) to a magnesium chloride support containing a magnesium chloride-alcoholate represented by the following Chemical Formula 1. [Chemical Formula 1] MgCl ２ ·x(R １ OH) In the above Chemical Formula 1, R １ is a C １－２０ organic group, x is from 0.01 to 3. [Chemical Formula 2] R ２ ｙ AlCl ３－ｙ In the above Chemical Formula 2, R ２ is, independently of each other, C １－１０ alkyl or C ３－１０ cycloalkyl, and y is from 1 to 2.

2. The magnesium chloride-alcoholate represented by the above Chemical Formula 1 is MgCl ２ and R １ OH are mixed to obtain a magnesium chloride-alcoholate solution, and produced by a method including the step of reducing the pressure of the magnesium chloride-alcoholate solution to obtain a solid magnesium chloride-alcoholate, the method for producing a Ziegler-Natta catalyst for linear low-density polyethylene polymerization according to Claim 1.

3. The method for producing a Ziegler-Natta catalyst for linear low-density polyethylene polymerization according to Claim 1, further comprising the step of further adding the alkylaluminum chloride represented by the above Chemical Formula 2 after the step of adding and reacting the metal compound.

4. The method for producing a Ziegler-Natta catalyst for linear low-density polyethylene polymerization according to Claim 1, wherein the metal compound further contains a Group IV or Group V metal.

5. The method for producing a Ziegler-Natta catalyst for linear low-density polyethylene polymerization according to Claim 1, wherein x is from 0.5 to 2.

0.

6. The foregoing R ２ is, independently of one another, C １－６ alkyl or C ３－６ cycloalkyl, The method for producing a Ziegler-Natta catalyst for linear low-density polyethylene polymerization according to Claim 1, wherein y is from 1 to 2.

7. The metal compound and the alkylaluminum chloride represented by the above Chemical Formula 2 are added in a molar ratio of 1:10 to 1:50, the method for producing a Ziegler-Natta catalyst for linear low-density polyethylene polymerization according to Claim 1.

8. The metal compound and the magnesium chloride support are reacted in a molar ratio of 1:0.1 to 1:30, the method for producing a Ziegler-Natta catalyst for linear low-density polyethylene polymerization according to Claim 1.

9. The metal compound is TiX ４ or (R ３ O) ｚ Ti(X) ４－ｚ and contains Here, the X is a halogen atom, and the R ３ is, independently of each other, C １－１０ alkyl, and the z is an integer of 1 to 4. A method for producing a Ziegler-Natta catalyst for linear low-density polyethylene polymerization according to claim 1.

10. The method for producing a Ziegler-Natta catalyst for linear low-density polyethylene polymerization according to Claim 9, wherein the metal compound is a mixed metal compound further containing a compound containing a Group V metal.

11. The alkylaluminum chloride is EtAlCl ２ , MeAlCl ２ , PrAlCl ２ , BuAlCl ２ or (C ２ H ５ ) ３／２ AlCl ３／２ The method for producing a Ziegler-Natta catalyst for linear low-density polyethylene polymerization according to claim 1

12. A Ziegler-Natta catalyst for linear low-density polyethylene polymerization produced by the production method according to any one of Claims 1 to 11.

13. A method for producing linear low-density polyethylene, comprising the step of contacting ethylene with the Ziegler-Natta catalyst for polymerizing linear low-density polyethylene according to claim 12.

14. The method for producing linear low-density polyethylene according to claim 13, wherein the linear low-density polyethylene has a density of 0.91 g / mL to 0.94 g / mL and a melt index (MI) measured according to ASTM D1238 of 1.0 g / 10 min to 5.0 g / 10 min.

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