Process for Producing Ziegler-Natta Catalyst for Low-Density Copolymerization

Abstract

The present disclosure relates to a method for manufacturing a Ziegler-Natta catalyst for use in low-density copolymerization, specifically to a manufacturing method including a step of reacting an alkylaluminum compound under a branched-chain alkyl alcohol or cycloalkyl alcohol solvent to produce a magnesium carrier. The Ziegler-Natta catalyst produced by the manufacturing method according to one embodiment has excellent catalytic activity. Therefore, by using it, it is possible to realize various physical properties and effectively manufacture a low-density copolymer with excellent copolymerization performance.

Description

Technical Field

[0001] The present disclosure relates to a method for producing a Ziegler-Natta catalyst for use in producing a low-density copolymer and a method for producing a low-density copolymer using the Ziegler-Natta catalyst produced thereby.

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 the Ziegler-Natta catalyst are determined according to the catalyst used, it is important to produce a catalyst that can enhance productivity and produce a polymer with a uniform distribution.

[0004] Although much development work has been done for the production of Ziegler-Natta catalysts, some methods have aspects that are not easy to produce catalysts in mass production, such as the production conditions being quite sensitive or a large amount of impurities or waste being formed. U.S. Patent No. 8003741 describes a production method in which a magnesium compound is dissolved in alcohol and then a titanium compound is added, but it has the disadvantages of a complicated production 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 producing a Ziegler-Natta catalyst for use in producing a low-density copolymer. Another embodiment aims to provide a Ziegler-Natta catalyst for use in producing a low-density copolymer produced by the production method according to the aforementioned one embodiment.

[0006] Another embodiment aims to provide a method for producing a low-density copolymer using a Ziegler-Natta catalyst for low-density copolymerization according to the above-described embodiment. **Means for Solving the Problems**

[0007] One embodiment includes a step of adding a branched-chain alkyl alcohol or a cycloalkyl alcohol to a mixture of dialkylmagnesium and a compound represented by the following Chemical Formula 1 to produce a solution containing a magnesium carrier, and

[0008] a step of adding a metal compound containing titanium (Ti) to the solution containing the magnesium carrier, and provides a method for producing a Ziegler-Natta catalyst for low-density copolymerization.

[0009] [Chemical Formula 1] R 1 x AlCl 3-x

[0010] In the above Chemical Formula 1, R 1 each independently represents C 1-10 alkyl or C 3-10 cycloalkyl, and x is 1 to 3.

[0011] Another embodiment provides a Ziegler-Natta catalyst for low-density copolymerization produced by the method for producing a Ziegler-Natta catalyst for low-density copolymerization according to the above-described embodiment.

[0012] Another embodiment provides a method for producing a low-density copolymer, including a step of contacting the Ziegler-Natta catalyst for low-density copolymerization according to the above-described embodiment with an olefin monomer. **Advantages of the Invention**

[0013] The present disclosure relates to a method for manufacturing a Ziegler-Natta catalyst for use in low-density copolymerization, and specifically to a manufacturing method including a step of reacting an alkylaluminum compound in a branched-chain alkyl alcohol or cycloalkyl alcohol solvent to produce a magnesium carrier. The Ziegler-Natta catalyst produced by the manufacturing method according to one embodiment has excellent catalytic activity, and thus by using it, it is possible to realize various physical properties and effectively produce a low-density copolymer having excellent copolymerization performance.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0015] The embodiments described in this specification may be modified into various different forms, and the technology according to one embodiment is not limited to the embodiments described later. Further, throughout the specification, "including" a certain component means that, unless otherwise stated to the contrary, it does not exclude other components but may further include other components.

[0016] The numerical ranges used in this specification include the lower limit value and the upper limit value, all values within that range, the increments logically derivable from the form and width of the defined range, all of the limited values among them, and all possible combinations of the upper and lower limits of the numerical ranges limited to different forms. As an example, when the content of a composition is limited to 10% - 80% or 20% - 50%, the numerical ranges of 10% - 50% or 50% - 80% must also be construed as those described in this specification. In this specification, unless otherwise defined, values outside the numerical range that may occur due to experimental error or rounding of values are also included in the defined numerical range.

[0017] Hereinafter, in this specification, unless otherwise defined, "about" can be regarded as a value within 30%, 25%, 20%, 15%, 10%, or 5% of the explicitly stated value.

[0018] Hereinafter, in this specification, "alkyl" is defined to mean both alkyl or cycloalkyl, and alkyl or cycloalkyl can be interpreted to include derivatives or ordinary substituents (such as halogen, etc.) that can be easily deformed by an ordinary technician to such an extent that similar effects can be achieved even without a specific definition.

[0019] The method for producing a Ziegler-Natta catalyst according to one embodiment includes a step of reacting dialkylmagnesium and an alkylaluminum compound in a branched-chain alkyl alcohol and / or cycloalkyl alcohol solvent, thereby providing a method capable of producing a Ziegler-Natta catalyst for low-density copolymerization with significantly improved catalytic activity. When polymerizing a low-density copolymer using the Ziegler-Natta catalyst produced by the method for producing a Ziegler-Natta catalyst according to the above-described one embodiment, compared with the case of using a catalyst produced using a linear alkyl alcohol such as conventional normal propyl alcohol as a solvent, a significantly higher catalyst mileage can be achieved. Further, the low-density copolymer polymerized using the Ziegler-Natta catalyst according to one embodiment has a lower proportion of the high-density region (homopolymer) and a higher proportion of the low-density region (copolymer) compared with commercially available products, and thus has a high elongation rate and excellent usability. Hereinafter, the method for producing a Ziegler-Natta catalyst for low-density copolymerization according to one embodiment and the polymerization of a low-density copolymer using the same will be described in detail.

[0020] One embodiment provides a step of adding a branched-chain alkyl alcohol and / or cycloalkyl alcohol to a mixture of dialkylmagnesium and a compound represented by the following Chemical Formula 1 to produce a solution containing a magnesium carrier (magnesium carrier solution),

[0021] and a step of adding a metal compound containing titanium (Ti) to the solution containing the magnesium carrier, and provides a method for producing a Ziegler-Natta catalyst for low-density copolymerization.

[0022] [Chemical Formula 1] R 1 x AlCl 3-x

[0023] In Chemical Formula 1, R 1 are each independently C 1-10 alkyl or C 3-10 cycloalkyl, and x is from 1 to 3.

[0024] According to the production method according to one embodiment, by reacting dialkylmagnesium with alkylaluminum represented by Chemical Formula 1 in a branched-chain alkyl alcohol or cycloalkyl alcohol solvent, a Ziegler-Natta catalyst excellent in catalytic activity can be produced. Therefore, when polymerizing a low-density copolymer using the Ziegler-Natta catalyst produced according to one embodiment, a low-density copolymer can be produced with a significantly increased yield (output) and / or catalyst mileage. Further, since the comonomer reactivity of the catalyst is excellent, the low-density copolymer produced by the catalyst has a higher ratio in the low-density region and a higher elongation ratio compared to a commercially available linear low-density copolymer produced by the prior art, and can have excellent physical properties.

[0025] The solution containing the magnesium carrier (or magnesium carrier slurry solution) produced by the production method of the Ziegler-Natta catalyst according to one embodiment is opaque, different from the conventionally known magnesium carrier solution, that is, it has a lower solubility than the conventional transparent magnesium carrier solution. The magnesium carrier solution according to one embodiment can achieve remarkable catalytic activity by having such solubility characteristics. Specifically, since the physical properties of the magnesium carrier according to one embodiment are very stable, it can contribute very effectively to the realization of high catalytic activity. Further, in the magnesium carrier of one embodiment, since a transition metal is supported outside the magnesium carrier, the catalytic activity can be significantly increased by increasing the active sites of the transition metal. In contrast, the conventionally produced transparent magnesium carrier solution (Comparative Example 1) forms an incomplete carrier due to coprecipitation of the magnesium carrier and the catalyst, and since the transition metal is supported inside and outside the carrier, the active sites of the transition metal decrease and the catalytic activity decreases.

[0026] The effects achieved by one embodiment as described above may be the effects achieved by using a branched-chain alkyl alcohol and / or a cycloalkyl alcohol as a solvent in the step of manufacturing the magnesium carrier solution. The step of manufacturing the solution containing the magnesium carrier is a step of forming a complex of magnesium and alcohol, and at this time, the alkyl group of the alcohol is an important influencing factor in the formation of the complex. In one embodiment, by using an alcohol in which a branched-chain alkyl is substituted or a cyclic alkyl is substituted, a trimeric (trimer, three-molecule polymer) aluminum trialkoxide can be formed, and thereby, when the magnesium-alcohol complex is formed, the aluminum trialkoxides further aggregate with each other to form an insoluble slurry.

[0027] In one embodiment, the dialkylmagnesium may be magnesium substituted with a linear or branched C 1-10 alkyl or C 3-10 cycloalkyl, each independently. Or, for example, C 1-6 alkyl, C 1-5 alkyl, C 2-5 alkyl, -CH3, -CH2CH3, -CH2CH2CH3, -CH2CH2CH2CH3, C 3-6 cycloalkyl, C 4-6 cycloalkyl, and C 5-6 substituted with two substituents independently selected from cycloalkyl may also be possible. In one embodiment, the dialkylmagnesium may be Et(n-Bu)Mg (Ethyl normal butyl magnesium, BEM).

[0028] In one embodiment, the magnesium carrier may include an adduct or complex of magnesium, alcohol, and / or alkyl. For example, the magnesium carrier is Mg(OR)2·a[Al b (OR) 3bIt may be represented by. At this time, the above a may be, for example, 0.1 to 10, 0.1 to 6, 0.5 to 6, 0.5 to 3, 0.8 to 2, 0.8 to 1.5, or 1. Further, the above b may be, for example, 0.1 to 10, 0.1 to 6, 0.1 to 5, 0.1 to 3, 0.1 to 1, 0.2 to 0.8, or 0.5. For example, the magnesium carrier is Mg(OR)·[Al 0.5 (OR) 1.5 . Further, since the above R may be, for example, an alkyl group derived from alcohol, it may be a branched-chain alkyl group or a cycloalkyl group.

[0029] In one embodiment, the above R 1 are each independently a straight-chain or branched-chain C 1-6 alkyl, C 1-5 alkyl, C 1-3 alkyl, -CH3, -CH2CH3, -CH2CH2CH3, -CH2CH2CH2CH3, -CH(CH3)CH2CH3, C 3-6 cycloalkyl, C 4-6 cycloalkyl, or C 5-6 cycloalkyl, and at this time, the above R 1 may all be the same substituent. However, this is only an example and is not necessarily limited thereto.

[0030] In one embodiment, the above x may be, for example, 1, 3 / 2, 2, 5 / 2, or 3. Specifically, the compound represented by Chemical Formula 1 may be trialkylaluminum (R 1 3Al) in which x is 3. In one embodiment, the compound represented by Chemical Formula 1 may be triethylaluminum (C6H 15 Al, Triethyl aluminium) or tributylaluminum (C 12 H 27 Al, Tributyl aluminium) (or triisobutylaluminum (Triisobutyl aluminium)).

[0031] The manufacturing method according to one embodiment may be carried out in a normal organic solvent. For example, it may be carried out in a saturated hydrocarbon solvent of C 5-20 Specifically, pentane, hexane, heptane, octane, nonane, or decane, etc. may be used, or a mixed solvent thereof may also be used.

[0032] The manufacturing method according to one embodiment may further include a step of adding a compound represented by the following Chemical Formula 2 after the step of adding a metal compound.

[0033] [Chemical Formula 2] R 2 y AlCl 3-y

[0034] In the Chemical Formula 2, R 2 are each independently C 1-10 alkyl or C 3-10 cycloalkyl, and y is 1 to 2.

[0035] At this time, the R 2 are each independently linear or branched C 1-6 alkyl, C 1-5 alkyl, C 2-5 alkyl, -CH3, -CH2CH3, -CH2CH2CH3, -CH2CH2CH2CH3, C 3-6 cycloalkyl, C 4-6 cycloalkyl, or C 5-6 cycloalkyl, and at this time, the R 2 may all be the same substituent. However, this is only an example and is not necessarily limited thereto. In one embodiment, the y may be, for example, 0, 1 / 2, 1, 3 / 2, or 2.

[0036] In one embodiment, the compound represented by the Chemical Formula 2 is C6H 15 Al2Cl3 (that is, (C2H5) 3 / 2 AlCl 3 / 2)(Ethyl aluminium sesquichloride), EtAlCl2 (Ethyl aluminium dichloride), MeAlCl2 (Methyl aluminium dichloride), PrAlCl2 (Propyl aluminium dichloride), or BuAlCl2 (Butyl aluminium dichloride) may be used, and one or more of them may be used simultaneously or in combination. In one embodiment, the alkylaluminum chloride compound represented by Chemical Formula 2 may be a monomer or a dimer.

[0037] In one embodiment, the molar ratio of the metal compound to the compound represented by Chemical Formula 2 may be 1:0.1 to 1:15, 1:0.1 to 1:10, 1:1 to 1:10, 1:2 to 1:10, 1:2 to 1:8, 1:3 to 1:5, or about 1:5. However, this is only an example and is not necessarily limited thereto.

[0038] In one embodiment, the molar ratio of the metal compound to the magnesium carrier may be 1:5 to 1:30, 1:5 to 1:30, 1:10 to 1:30, 1:10 to 1:25, 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 metal compound may further contain a transition metal, for example, it may further contain a Group IV or Group V metal. Specifically, the metal compound may further contain one or more metals selected from the group consisting of Zr, Hf, V, Nb, and Ta. At this time, the metal may be contained in the form of chloride, alkoxy chloride, alkylated product, etc., but this is only an example and is not necessarily limited thereto.

[0040] In one embodiment, the metal compound containing titanium (Ti) is TiX4 or (R 3 O) z Ti(X) 4-zIt may be included. At this time, the 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 the z is an integer from 1 to 4 (for example, 1, 2, 3, or 4). Specific examples of the metal compound may be TiCl4, TiBr4, TiI4, Ti(OBu)4, Ti(Oi-Pr)4, Ti(OEt)4, Ti(OEt)2(Cl)2, or Ti(OEt)(Cl)3, etc. However, this is only an example and is not necessarily limited thereto.

[0041] 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 (TiCl4) and a Group V metal compound containing a Group V metal (VOCl3).

[0042] In one embodiment, the branched-chain alkyl alcohol or cycloalkyl alcohol may be added in a molar amount exceeding 1 times the molar amount of the dialkylmagnesium. For example, it may be added in a molar amount of 1.2 times or more, 1.5 times or more, 2.0 times or more, 10 times or less, 8 times or less, 5 times or less, 4 times or less, or 3.5 times or less of the molar amount of the dialkylmagnesium. Or, the molar ratio of the dialkylmagnesium to the branched-chain alkyl alcohol or cycloalkyl alcohol may be 1:1.2 to 1:10, 1:1.5 to 1:10, 1:1.5 to 1:8, 1:1.5 to 1:6, 1:1.5 to 1:5, 1:2 to 1:8, 1:2 to 1:4, or 1:1.5 to 1:3.5.

[0043] In one embodiment, the branched-chain alkyl alcohol or cycloalkyl alcohol may be added in a molar amount exceeding twice the molar amount of the compound represented by Chemical Formula 1. For example, it may be added in a molar amount of 2.2 times or more, 2.5 times or more, 3 times or more, 4 times or more, 10 times or less, 9 times or less, 8 times or less, or 7 times or less the molar amount of the compound represented by Chemical Formula 1. Alternatively, the molar ratio of the compound represented by Chemical Formula 1 to the branched-chain alkyl alcohol or cycloalkyl alcohol may be 1:2.5 to 1:10, 1:2.5 to 1:9, 1:2.5 to 1:8, 1:2.5 to 1:7, 1:3 to 1:10, or 1:4 to 1:10.

[0044] In one embodiment, the step of adding the branched-chain alkyl alcohol or cycloalkyl alcohol may be carried out at a temperature of about 10°C to -50°C, 0°C to -30°C, -5°C to -25°C, or -10°C to -20°C. Further, after the addition of the branched-chain alkyl alcohol or cycloalkyl alcohol, a step of reacting for about 120 minutes to 300 minutes, 180 minutes to 300 minutes, 200 minutes to 300 minutes, 220 minutes to 260 minutes, or about 240 minutes may be carried out.

[0045] The branched-chain alkyl alcohol according to one embodiment is not particularly limited as long as it is an alcohol in which a branched-chain alkyl group is substituted. For example, a branched-chain alkyl alcohol of C 3-20 ; a branched-chain alkyl alcohol of C 3-15 ; a branched-chain alkyl alcohol of C 3-10 ; a branched-chain alkyl alcohol of C 3-8 ; a branched-chain alkyl alcohol of C 3-6 ; a branched-chain alkyl alcohol of C 3-5 ; or a branched-chain alkyl alcohol of C 3-4It may be a branched-chain alkyl alcohol. Specific examples include isopropyl alcohol, isobutyl alcohol, tert-butyl alcohol, sec-butyl alcohol, 2-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-pentanol, neopentanol, 2-methyl-2-butanol, 3-methyl-2-butanol, 2-hexanol, 3-hexanol, 2-methyl-1-pentanol, 3-methyl-1-pentanol, 4-methyl-1-pentanol, 2-methyl-2-pentanol, 3-methyl-2-pentanol, 4-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-3-pentanol, 2,2-dimethyl-1-butanol, 2,3-dimethyl-1-butanol, 3,3-dimethyl-1-butanol, 2,3-dimethyl-2-butanol, 3,3-dimethyl-2-butanol, 2-ethyl-1-butanol, or a combination of two or more thereof. Also, the alcohol is only an example and is not particularly limited as long as it is an alcohol having a branched-chain alkyl chain.

[0046] The cycloalkyl alcohol according to one embodiment is not particularly limited as long as it is an alcohol substituted with a cyclic alkyl group. For example, C 3-20 cycloalkyl alcohol, C 3-15 cycloalkyl alcohol, C 3-10 cycloalkyl alcohol, C 3-8 cycloalkyl alcohol, C 3-6 cycloalkyl alcohol, C 4-6 cycloalkyl alcohol, or C 5-6It may also be a cycloalkyl alcohol. Specific examples include cyclopropanol, cyclobutanol, cyclopentanol, cyclohexanol, cycloheptanol, cyclooctanol, cyclononanol, cyclodecanol, bicyclo[2.1.1]hexanol, bicyclo[2.2.1]heptanol, octahydropentalenol, octahydro-1H-indenol, or a combination of two or more thereof. Alternatively, the cycloalkyl alcohol according to the above-described embodiment may include an alcohol substituted with a cyclic alkyl group containing an unsaturated bond, and may include, without limitation, a structure in which an arbitrary substituent is substituted on the cycloalkyl group. Further, the cycloalkyl alcohol is merely an example, and alcohols having a cycloalkyl group are not particularly limited.

[0047] Another embodiment provides a Ziegler-Natta catalyst for producing a low-density copolymer, which is produced by the method for producing a Ziegler-Natta catalyst for producing a low-density copolymer according to an embodiment.

[0048] Still another embodiment provides a method for producing a low-density copolymer using the Ziegler-Natta catalyst for producing a low-density copolymer according to the above-described embodiment. Specifically, it provides a method for producing a low-density copolymer, which includes the step of contacting an olefin monomer with the Ziegler-Natta catalyst for producing a low-density copolymer according to an embodiment.

[0049] In one embodiment, the olefin monomer may be, for example, an olefin monomer having 2 to 20 carbon atoms, 2 to 15 carbon atoms, or 4 to 10 carbon atoms. In one embodiment, the low-density copolymer may be, for example, a linear low-density copolymer, and as an example, it may be linear low density polyethylene.

[0050] In one embodiment, the low-density copolymer 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 low-density copolymer has a melt index (MI) measured at about 190 °C of 0.1 g / 10 min to 5.0 g / 10 min, 0.1 g / 10 min to 4.0 g / 10 min, 0.1 g / 10 min to 3.0 g / 10 min, 0.1 g / 10 min to 2.0 g / 10 min, 0.1 g / 10 min to 1.0 g / 10 min, 0.2 g / 10 min to 1.0 g / 10 min, 0.4 g / 10 min to 1.0 g / 10 min, or 0.5 g / 10 min to 0.9 g / 10 min in accordance with ISO 1133:1997 or ASTM D1238:1999, but this is only an example and is not necessarily limited thereto.

Example

[0051] Hereinafter, examples and experimental examples will be specifically illustrated and described. However, the examples and experimental examples described below illustrate a part of one embodiment, and the technology described in this specification is not limited thereto.

[0052] <Examples 1-1 to 1-4> 33 mL (30.0 mmol) of a 0.9 M heptane solution of ethyl normal butyl magnesium (BEM, [dialkyl magnesium]) was charged into a 500 mL flask, and 100 mL of normal heptane was charged. While stirring the solution, 3.50 g (15.0 mmol) of triethylaluminum (AlEt3, [aluminum compound-1]) was gradually added dropwise. Thereafter, while maintaining the reaction temperature at about 0 °C to -30 °C level, isopropyl alcohol (i-PrOH, [alcohol]) was gradually added dropwise in an equivalent amount as shown in Table 1 below, and the reaction was sufficiently carried out for about 4 hours to produce a magnesium carrier slurry solution with a concentration of 0.2 M.

[0053] 30 mL (6.00 mmol) of a 0.2 M magnesium carrier slurry solution ([carrier]) was charged into a 100 mL flask, and 3.3 mL (0.40 mmol) of a 5 wt% Ti(Oi-Pr)4 ([metal compound]) heptane solution was added and stirred for 4 hours or more. Then, 2 mL (2.00 mmol) of a 1.0 M ethylaluminum dichloride solution (C2H5AlCl2, [aluminum compound - 2]) diluted with hexane was added and stirred at room temperature for 6 hours or more to produce a reddish-brown catalyst (Ziegler-Natta) solution.

[0054] <Examples 2-1 to 2-4> The same method as in Examples 1-1 to 1-4 was carried out, but [metal compound] was changed to 3.28 mL (0.40 mmol) of a 5 wt% TiCl4 heptane solution to produce a reddish-brown catalyst (Ziegler-Natta) solution.

[0055] <Examples 3-1 to 3-4> The same method as in Examples 1-1 to 1-4 was carried out, but [aluminum compound - 1] was changed to 2.97 g (15.0 mmol) of triisobutylaluminum (Al(i-Bu)3) to produce a reddish-brown catalyst (Ziegler-Natta) solution.

[0056] <Examples 4-1 to 4-4> The same method as in Examples 1-1 to 1-4 was carried out, but [alcohol] was changed to isobutyl alcohol (i-BuOH) to produce a reddish-brown catalyst (Ziegler-Natta) solution.

[0057] <Examples 5-1 to 5-4> The same method as in Examples 1-1 to 1-4 was carried out, but [alcohol] was changed to 2-methyl-2-propyl alcohol (t-BuOH) to produce a reddish-brown catalyst (Ziegler-Natta) solution.

[0058] <Examples 6-1 to 6-4> It is carried out in the same manner as in Examples 1-1 to 1-4, but [alcohol] is changed to cyclohexanol (CHN) to produce a reddish-brown catalyst (Ziegler-Natta) solution.

[0059] <Comparative Examples 1-1 to 1-4> 33 mL (30.0 mmol) of a 0.9 M heptane solution of ethyl normal butyl magnesium (BEM, [dialkyl magnesium]) was charged into a 500 mL flask, and 120 mL of normal heptane was charged. While stirring the solution, 2.97 g (15.0 mmol) of triisobutylaluminum (Al(i-Bu)3, [aluminum compound - 1]) was gradually added dropwise. Then, while maintaining the reaction temperature at about 0 °C to -30 °C level, normal propyl alcohol (n-PrOH, [alcohol]) was gradually added dropwise in the equivalent amounts as shown in Table 1 below and the reaction was sufficiently carried out for about 4 hours to produce a 0.2 M concentration transparent magnesium carrier solution.

[0060] 30 mL (6.00 mmol) of a 0.2 M magnesium carrier slurry solution ([carrier]) was charged into a 100 mL flask, 0.36 mL (0.34 g, 1.20 mmol) of a heptane solution of Ti(Oi-Pr)4 ([metal compound]) was charged, and the mixture was stirred for 4 hours or more. Then, 24.00 mL (24.00 mmol) of a 1.0 M ethylaluminum dichloride solution (C2H5AlCl2, [aluminum compound - 2]) diluted with hexane was added and the mixture was stirred at room temperature for 6 hours or more to produce a brown catalyst (Ziegler-Natta) solution.

[0061] <Comparative Examples 2-1 to 2-4> It is carried out in the same manner as in Comparative Examples 1-1 to 1-4, but [aluminum compound - 1] is changed to triethylaluminum (AlEt3) to produce a catalyst (Ziegler-Natta) solution.

[0062] <Comparative Examples 3-1 to 3-4> It is carried out in the same manner as in Examples 1-1 to 1-4, but [alcohol] is changed to normal butyl alcohol (n-BuOH) to produce a catalyst (Ziegler-Natta) solution.

[0063]

Table 1(1)

Table 1(2)

[0064] 1) Dialkylmagnesium A: BEM 2) Aluminum compound - 1 B: AlEt3 / C: Al(i - Bu)3 3) Alcohol D: i - PrOH / E: i - BuOH / F: t - BuOH / G: CHN / H: n - PrOH / I: n - BuOH

[0065]

Table 2

[0066] 1) Metal compound J: Ti(Oi - Pr)4 / K: TiCl4 2) Aluminum compound - 2 L: C2H5AlCl2

[0067] <Experimental Example 1> Polymerization of Low - Density Copolymer 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, and the temperature of the reactor was raised to 180 °C while stirring, and then ethylene was introduced into the reactor at 30 bar. 1.7 μmol of the catalyst produced in Example 1-4, Example 2-4, Example 3-4, Example 4-4, Example 5-4, Example 6-4, Comparative Example 1-4, and Comparative Example 3-4 was diluted with 3 mL of a saturated hydrocarbon solvent (methylcyclohexane) and transferred to a catalyst pot, and the catalyst pot was pressurized with 50 bar of anhydrous nitrogen. After the autoclave reactor was saturated with ethylene, the catalyst in the catalyst pot was introduced into the reactor under isothermal conditions at 180 °C, and semi-batch polymerization with continuous supply of ethylene was carried out for 10 minutes. Then, 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 yield, catalyst mileage, melting index, and density of the obtained linear low-density polyethylene were measured and shown in Table 3 below.

[0068] At this time, the catalyst mileage was defined as the value obtained by dividing the mass of the produced LLDPE by the mass of the catalyst. The melting index was measured by testing at 190 °C according to the ASTM D1238 standard, and the density was measured using a density gradient column.

[0069]

Table 3

[0070] Referring to Table 3 above, it can be confirmed that when polymerizing using the catalyst produced in the examples, the yield of the copolymer is significantly increased and the catalyst mileage value is increased compared to the case of polymerizing using the catalyst produced in the comparative examples.

[0071] <Experimental Example 2> Crystallization elution fractionation (CEF) To analyze the physical properties of the polymers produced using the catalysts of Examples 1-4 by the crystallization elution fractionation method (CEF), the POLYMER-CHAR CRYTEX-42 instrument was utilized and tested using a TCB (trichlorobenzene) solution. At this time, commercially available products A (Dow (DOWLEX 2045G), MI: 1.00 g / 10 min, density: 0.9200 g / mL) and B (SK (FN810), MI: 0.99, density: 0.9198 g / mL) were prepared and experimented as a comparative group. The results are shown in Figure 1.

[0072] From the above experiment, it was confirmed that in the CEF spectrum, the polymers produced using the catalysts of the examples had a lower proportion in the high-density region (homopolymer) of about 80 °C to 100 °C and a higher proportion in the low-density region (copolymer) of about 50 °C to 80 °C compared to the commercially available products. Therefore, it can be seen that by using the catalysts of the examples, low-density copolymers with high elongation can be effectively produced.

[0073] <Experimental Example 3> Shape Analysis of Magnesium Carrier Solution To analyze the transparency and solubility of the magnesium carrier solutions depending on the type of alcohol solvent, the shapes of the respective magnesium carrier solutions produced in the above examples and comparative examples were observed and shown in Table 4 below. Among them, photographs of the magnesium carrier solutions produced in Examples 1-4, Examples 3-4, Examples 4-4, Examples 5-4, Examples 6-4, Comparative Example 1-4, Comparative Example 2-4, and Comparative Example 3-4 are taken and shown in Figure 2.

[0074]

Table 4(1)

Table 4(2)

[0075] As can be confirmed from Table 4 and FIG. 2, the magnesium carrier solution produced using a branched-chain alkyl alcohol or cycloalkyl alcohol as a solvent was observed to have an opaque shape, while the magnesium carrier solution produced using a straight-chain alkyl alcohol as a solvent was observed to have a transparent shape. From this, it can be confirmed that in the production of the magnesium carrier solution, the alcohol solvent greatly contributes to the shape of the solution. In particular, by using an alcohol substituted with a branched-chain alkyl such as isopropyl, isobutyl, tert-butyl, or an alcohol substituted with a cyclic alkyl such as cyclohexane, a magnesium carrier with very stable physical properties can be produced, and it can be seen that by using this, a Ziegler-Natta catalyst with high activity for producing a low-density copolymer can be produced.

[0076] 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 the specific examples and should be interpreted by the appended claims.

Claims

1. Adding a branched-chain alkyl alcohol or a cycloalkyl alcohol to a mixture of dialkylmagnesium and a compound represented by the following Chemical Formula 1 to produce a solution containing a magnesium carrier; Adding a metal compound containing titanium (Ti) to the solution containing the magnesium carrier; A method for producing a Ziegler-Natta catalyst for low-density copolymerization, comprising: [Chemical Formula 1] R １ ｘ AlCl ３－ｘ In the above Chemical Formula 1, R １ is, independently of each other, C １－１０ alkyl or C ３－１０ cycloalkyl, and x is from 1 to 3.

2. The method for producing a Ziegler-Natta catalyst for low-density copolymerization according to Claim 1, further comprising, after the step of adding the metal compound, adding a compound represented by the following Chemical Formula 2. [Chemical Formula 2] R ２ ｙ AlCl ３－ｙ In the above Chemical Formula 2, R ２ is, independently of one another, C １－１０ alkyl or C ３－１０ cycloalkyl, and y is from 1 to 2.

3. Said R １ is, independently of each other, C １－６ alkyl or C ３－６ cycloalkyl, and a process for producing a Ziegler-Natta catalyst for low-density copolymerization according to claim 1.

4. The method for producing a Ziegler-Natta catalyst for low-density copolymerization according to Claim 1, wherein the branched-chain alkyl alcohol or the cycloalkyl alcohol is added in a molar amount exceeding 1 times the number of moles of the dialkylmagnesium.

5. The method for producing a Ziegler-Natta catalyst for low-density copolymerization according to Claim 1, wherein the branched-chain alkyl alcohol or the cycloalkyl alcohol is added in a molar amount exceeding 2 times the number of moles of the compound represented by Chemical Formula 1.

6. Said R ２ is, independently of one another, C １－６ alkyl or C ３－６ cycloalkyl, and a method for producing a Ziegler-Natta catalyst for use in the polymerization of a low-density copolymer according to claim 2.

7. The compound represented by the chemical formula 2 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 low-density copolymerization according to claim 2

8. The method for producing a Ziegler-Natta catalyst for low-density copolymerization according to Claim 2, wherein the molar ratio of the metal compound to the compound represented by Chemical Formula 2 is 1:0.1 to 1:

15.

9. The method for producing a Ziegler-Natta catalyst for low-density copolymerization according to Claim 1, wherein the molar ratio of the metal compound to the magnesium carrier is 1:5 to 1:

30.

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

11. The metal compound is TiX ４ or (R ３ O) ｚ Ti(X) ４－ｚ and contains At this time, the X is a halogen atom, and the R ３ are each independently C １－１０ alkyl, and the z is an integer of 1 to 4. The method for producing a Ziegler-Natta catalyst for use in producing a low-density copolymer as claimed in claim 1.

12. The method for producing a Ziegler-Natta catalyst for low-density copolymerization according to Claim 11, wherein the metal compound is a mixed metal compound further containing a compound containing a Group V metal.

13. The branched-chain alkyl alcohol is a C ３－１０ branched-chain alkyl alcohol, and the method for producing a Ziegler-Natta catalyst for low-density copolymerization according to claim 1.

14. The method for producing a Ziegler-Natta catalyst for low-density copolymerization according to Claim 1, wherein the branched-chain alkyl alcohol is one or a combination of two or more selected from isopropyl alcohol, isobutyl alcohol, and tert-butyl alcohol.

15. The cycloalkyl alcohol is C ３－１０ The method for producing a Ziegler-Natta catalyst for low-density copolymerization according to claim 1, which is a cycloalkyl alcohol of

16. The method for producing a Ziegler-Natta catalyst for low-density copolymerization according to claim 1, wherein the cycloalkyl alcohol is cyclohexanol.

17. A Ziegler-Natta catalyst for low-density copolymerization produced by the production method according to any one of claims 1 to 16.

18. A method for producing a low-density copolymer, comprising a step of bringing an olefin monomer into contact with the Ziegler-Natta catalyst for low-density copolymerization according to claim 17.

19. The method for producing a low-density copolymer according to claim 18, wherein the low-density copolymer has a density of 0.91 g / mL to 0.94 mL and a melt index measured according to ASTM D1238 of 0.1 g / 10 min to 5.0 g / 10 min.

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