Preparation method of polyolefin elastomer copolymer with ultra-low density and high elasticity and polyolefin elastomer copolymer prepared thereby

Abstract

The present invention provides a method for preparing a polyolefin elastomer copolymer and a polymer for automotive interior and exterior decoration materials, shoes or cable covering materials, which comprises the polyolefin elastomer copolymer prepared thereby. The preparation method comprises the following steps: (a) adding a liquid olefin monomer selected from 1-butene monomer, 1-hexene monomer and 1-octene monomer, ethylene gas and a titanium-supported Ziegler-Natta type catalyst into a reactor; and (b) carrying out a polymerization reaction at 50 to 70 °C.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2020-0124282, filed on September 24, 2020, and includes all the contents disclosed in the documents of this Korean patent application as part of this specification.

[0002] The present invention relates to a method for preparing a polyolefin elastomer copolymer having ultra-low density and high elasticity, and a polyolefin elastomer copolymer prepared thereby. Background Art

[0003] As a thermoplastic resin having rubber-like properties, polyolefin elastomers are recyclable, unlike thermosetting resins such as polyurethane and vulcanized rubber, which are not recyclable. Therefore, they have attracted much attention as plastic resins that will replace rubber and polyurethane elastomers. Polyolefin elastomers are known as thermoplastic elastomers and have various uses by being kneaded with polyethylene or polypropylene resins, and can be used for automotive interior and exterior decoration materials, shoes, cables, etc.

[0004] Polyolefin elastomers are generally made by copolymerizing ethylene with 1-butene or ethylene with 1-octene using a metallocene catalyst. However, since this method uses an expensive metallocene catalyst, it has poor economy. According to the characteristics of the metallocene catalyst, the polyolefin elastomer prepared has a narrow molecular weight distribution, and when kneaded with polyethylene or polypropylene, the workability is reduced, and it has the disadvantages of high density and low elasticity.

[0005] Therefore, in order to overcome the above disadvantages, various methods for polymerizing polyolefin elastomers are being developed. For example, polyolefin elastomers obtained by copolymerizing known 1-butene with propylene using a Ziegler-Natta catalyst are being developed.

[0006] However, the above polyolefin elastomers have not found a clue to solve the problems of low workability and high density and low elasticity that have been problems in the prior art.

[0007] In addition, in fact, there is no polyolefin elastomer copolymerized from ethylene and 1-butene or ethylene and 1-octene that can replace the existing ones used for automotive interior and exterior decoration materials, shoes, cable covering materials, etc. in terms of physical properties.

[0008] On the other hand, commercially produced butene-1 copolymers generally have the disadvantage of production equipment such as high-cost devolatilization devices required for removing solvents because they are produced by solution polymerization. Therefore, improvement is also needed in this regard.

[0009] Prior Art Documents

[0010] Patent Documents

[0011] (Patent Document 1) Korean Patent Publication No. 10-2011-0138254 Summary of the Invention

[0012] Technical Problem

[0013] In order to solve the above problems in the prior art, the inventor of the present invention made painstaking efforts and discovered an efficient preparation method of a polyolefin elastomer copolymer having elasticity and processability sufficient for use in automotive interior and exterior decoration materials, shoes, cable covering materials, etc., and completed the present invention.

[0014] Therefore, an object of the present invention is to provide an efficient preparation method of a polyolefin elastomer copolymer having ultra-low density, high elasticity, and excellent processability.

[0015] In addition, an object of the present invention is to provide a preparation method of a polyolefin elastomer copolymer capable of efficiently preparing a copolymer using an existing olefin homopolymer preparation device.

[0016] In addition, an object of the present invention is to provide a polyolefin elastomer copolymer having ultra-low density, high elasticity, and excellent processability sufficient for use in automotive interior and exterior decoration materials, shoes, cable covering materials, etc., which is prepared by the above preparation method.

[0017] Technical Solution

[0018] To achieve the above object, the present invention provides a preparation method of a polyolefin elastomer copolymer, which includes the following steps:

[0019] (a) Adding a liquid olefin monomer selected from 1-butene monomer, 1-hexene monomer, and 1-octene monomer, ethylene gas, and a Ziegler-Natta type titanium-supported catalyst to a reactor; and

[0020] (b) Performing a polymerization reaction at 50 to 70 °C.

[0021] In addition, the present invention provides a polyolefin elastomer copolymer prepared by the above method.

[0022] Technical Effect

[0023] According to the preparation method of the polyolefin elastomer copolymer of the present invention, a polyolefin elastomer copolymer having ultra-low density, high elasticity, and processability can be prepared very efficiently.

[0024] In addition, according to the preparation method of the polyolefin elastomer copolymer of the present invention, a polyolefin elastomer copolymer can be efficiently prepared using an existing olefin homopolymer preparation device.

[0025] In addition, since the polyolefin elastomer copolymer of the present invention provides low density, high elasticity, and excellent processability sufficient for use in automotive interior and exterior decoration materials, shoes, cable covering materials, etc., it can be very effectively used in the entire industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a conceptual diagram showing the preparation apparatus (a) of the existing olefin homopolymer and the preparation apparatus (b) for preparing the polyolefin elastomer copolymer of the present invention.

[0027] Figure 2 It is a graph showing the density of the polyolefin elastomer prepared in the examples of the present invention.

[0028] Figure 3 It is a graph showing the molecular weight distribution (Mn / Mw) of the polyolefin elastomer prepared in the examples of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, the present invention will be described in detail.

[0030] Unless otherwise specified, all numbers, values, and / or expressions used in this specification to represent the amounts of components, reaction conditions, polymer compositions, and complexes should be understood to be modified by the term "about" in all cases, as this is an approximation reflecting the various uncertainties arising in the process of obtaining these values from inherently different numbers. In addition, when a numerical range is disclosed in this application, the range is continuous and includes all values from the minimum value of the range to the maximum value including the maximum value, unless otherwise specified. Furthermore, when these ranges refer to integers, all integers from the minimum value to the maximum value including the maximum value are included, unless otherwise specified.

[0031] In this specification, when a range is described for a variable, the variable should be understood to include all values within the described range, including the multiple endpoints described in the range. For example, the range of "5 to 10" includes not only the values of 5, 6, 7, 8, 9, and 10, but also any sub-ranges such as 6 to 10, 7 to 10, 6 to 9, 7 to 9, etc., and also any values between appropriate integers within the described range such as 5.5, 6.5, 7.5, 5.5 to 8.5, and 6.5 to 9. In addition, for example, the range of "10% to 30%" should be understood to include not only values such as 10%, 11%, 12%, 13%, etc. and all integers including 30%, but also any sub-ranges such as 10% to 15%, 12% to 18%, 20% to 30%, etc., and also any values between appropriate integers within the described range such as 10.5%, 15.5%, 25.5%.

[0032] The preparation method of the polyolefin elastomer copolymer of the present invention comprises the following steps:

[0033] (a) Adding a liquid olefin monomer selected from 1-butene monomer, 1-hexene monomer, and 1-octene monomer, ethylene gas, and a titanium-supported Ziegler-Natta catalyst to a reactor; and

[0034] (b) Conducting a polymerization reaction at 50-70°C.

[0035] The copolymer preparation method of the present invention is carried out by bulk polymerization using a liquid olefin monomer and a gaseous ethylene monomer to replace the solution polymerization method. Currently, in the generally commercialized solution polymerization method, components soluble in the solvent remain in the resin, resulting in limitations in improving stereoregularity. Moreover, additional production equipment such as a devolatilization device is required to remove the solvent. However, in the present invention, no additional polymerization solvent is used, so a high-purity olefin-ethylene copolymer with a high degree of polymerization can be prepared.

[0036] In the prior art, an expensive metallocene catalyst is used to copolymerize ethylene with an olefin monomer. Conversely, in the present invention, a cheap Ziegler-Natta catalyst is used. Compared with the metallocene catalyst, a polyolefin elastomer copolymerized from ethylene and an olefin with a wider molecular weight distribution can be prepared, thus providing a polyolefin elastomer with excellent processability.

[0037] In addition, a polyolefin elastomer copolymer with ultra-low density and high elasticity can be prepared very efficiently.

[0038] The polyolefin elastomer copolymer prepared by the above method can be prepared with various olefin contents, melt flow rate (MFR) of the resin, and melting temperature by adjusting the operating conditions, thus having the advantage of being able to simultaneously meet the physical properties required for various application products such as automotive interior and exterior decoration materials, shoes, and cables.

[0039] In the preparation method of the present invention, in the step (a), either ethylene gas or the titanium-supported Ziegler-Natta catalyst can be added first, and after raising the temperature of the reactor to 50-70°C, the other one can be added.

[0040] This addition method can adjust the ethylene content in the prepared polyolefin elastomer, so it is preferred.

[0041] In the present invention, when adding the titanium-supported Ziegler-Natta catalyst, based on 1 mol of the olefin monomer, the titanium content reaches 0.5-3.0 μmol; ethylene gas is supplied during the reaction to maintain a partial pressure of 0.1-2.0 MPa, and more preferably, a partial pressure of 0.2-1.0 MPa.

[0042] The content of titanium refers to the amount of titanium supported on the carrier of the Ziegler-Natta type catalyst. Therefore, the usage amount of the Ziegler-Natta type catalyst depends on the amount of titanium.

[0043] The Ziegler-Natta type catalyst, as a catalyst used in the olefin polymerization process, can be composed of a titanium (Ti) active component, a halogen ligand, a carrier, or a ligand-carrier. Specifically, the Ziegler-Natta type catalyst can typically use a catalyst in which a titanium (Ti) active metal is supported on a magnesium (Mg)-containing carrier. More specifically, it can be a catalyst in which a titanium (Ti) active metal is supported on a magnesium chloride carrier.

[0044] When the Ziegler-Natta type titanium-supported catalyst within the above range is not included, due to the low catalyst activity, the polymerization reaction is difficult to proceed efficiently. When it is used in excess beyond the range, since the catalyst is used in excess relative to the input amount of the monomer, the cost increases. After the reaction, the residual titanium catalyst in the product will cause a decline in the physical properties of the product.

[0045] Preferably, the ethylene gas is supplied at 0.1 - 2.0 MPa during the reaction. When the ethylene gas is supplied at a pressure less than 0.1 MPa, the ethylene content in the prepared polyolefin elastomer is insufficient to exhibit the physical properties of the polyolefin elastomer. When it is greater than 2.0 MPa, only ethylene polymerizes, and thus a copolymer of ethylene and an olefin monomer, that is, a polyolefin elastomer, cannot be prepared.

[0046] In the preparation method of the present invention, in the step (a), relative to every 1 mol content of titanium, 50 - 700 mol of an aluminum-based cocatalyst and 1 - 100 mol of a silane-based cocatalyst can be further added.

[0047] More preferably, relative to every 1 mol content of titanium, 400 - 600 mol of an aluminum-based cocatalyst and 10 - 50 mol of a silane-based cocatalyst can be further added.

[0048] The aluminum-based cocatalyst has the function of a polymerization cocatalyst for coordinative polymerization with titanium (Ti) of the main catalyst, and the function of removing catalyst poisons by reacting with impurity oxygen molecules contained in the monomer. The aluminum-based cocatalyst can use an aluminum compound combined with two or more selected from halogen atoms and C1-C10 alkyl groups. Specifically, the aluminum-based cocatalyst can use at least one selected from diethylaluminum chloride (DEAC), ethylaluminum dichloride (EADC), di-n-butylaluminum chloride (DNBAC), diisobutylaluminum chloride (DIBAC), triethylaluminum (TEA), triisobutylaluminum (TIBA), tri-n-hexylaluminum (TNHA), tri-n-octylaluminum (TNOA), tri-n-decylaluminum (TNDA), but the present invention is not limited thereto.

[0049] Relative to 1 mol of titanium in the main catalyst, the usage range of the aluminum-based cocatalyst can be 50-700 mol, more preferably 400-600 mol. When the content of the aluminum-based cocatalyst is less than 50 mol, aluminum cannot well play the role of a cocatalyst participating in coordinative polymerization and the role of removing catalyst poisons, thus reducing the conversion rate of raw materials. On the contrary, when the content of the aluminum-based cocatalyst is greater than 700 mol, the added effect caused by increasing the usage amount is not obvious, so the efficiency is low.

[0050] The silane-based cocatalyst has the function of increasing the stereoregularity of the copolymer. The silane-based cocatalyst can use at least one selected from monoalkoxysilane compounds, dialkoxysilane compounds, and trialkoxysilane compounds combined with two or more selected from C1-C10 alkyl groups, C1-C10 alkoxy groups, and C6-C12 aryl groups. Specifically, the silane-based cocatalyst can use at least one selected from diphenyldimethoxysilane, phenyltrimethoxysilane, isobutylmethoxysilane, diisobutyldimethoxysilane, cyclohexylmethyldimethoxysilane, diisopropyldimethoxysilane, etc., but the present invention is not limited thereto.

[0051] Relative to 1 mol of titanium in the main catalyst, the usage range of the silane-based cocatalyst can be 1-100 mol, more preferably 10-30 mol. When the content of the silane-based cocatalyst is less than 1 mol, the crystallinity is reduced due to the decrease in stereoregularity, thereby reducing the mechanical properties. On the contrary, when it is greater than 100 mol, the added effect caused by increasing the usage amount is not obvious, so the efficiency is low.

[0052] In addition, when forming the catalyst system of the present invention, the conversion rate, stereoregularity, and molecular weight of the copolymer synthesized by the content ratio of the aluminum-based cocatalyst and the silane-based cocatalyst may change. Preferably, as the cocatalyst, the molar ratio of the aluminum-based cocatalyst to the silane-based cocatalyst is 10 to 30:1, more preferably 20 to 30:1. When the molar ratio is less than 10:1, although the stereoregularity is improved, due to the low concentration of the aluminum-based cocatalyst, the coordination polymerization conversion rate decreases, and the efficiency may be low in removing catalyst poisons. Conversely, when the molar ratio is greater than 30:1, the titanium active sites are fully activated, and due to the removal of catalyst poisons, an effect of excellently maintaining catalytic activity can be obtained. However, it is difficult to obtain a copolymer with excellent stereoregularity, and a viscous feeling is generated due to the production of low-molecular-weight polymers.

[0053] In the preparation method of the present invention, in the step (a), 1 to 200 mmol of hydrogen can be further added relative to each 1 mol of olefin monomer. More preferably, 50 to 200 mmol of hydrogen is further added relative to each 1 mol of olefin monomer. Even more preferably, 100 to 200 mmol of hydrogen is added.

[0054] The hydrogen is used as a molecular weight regulator. When the content of the hydrogen is less than 1 mmol, the copolymerization reaction of ethylene and the olefin monomer is not initiated, and a problem of significantly reducing the polymerization rate may occur. When the content of the hydrogen is greater than 200 mmol, the molecular weight of the prepared polyolefin elastomer is greatly reduced, and thus a problem of being unable to obtain the required physical properties may occur.

[0055] In the preparation method of the present invention, preferably, the polymerization reaction in the step (b) is carried out for 0.5 to 3 hours. When the reaction time is less than 0.5 hours, the degree of polymerization is low, and a problem of being unable to obtain the required molecular weight may occur. When it is greater than 3 hours, over-polymerization occurs, and the viscosity of the product increases sharply, resulting in problems in the subsequent processes after the polymerization reaction. Therefore, it is not preferred.

[0056] In the preparation method of the present invention, while supplying the hydrogen, an inert gas can be further supplied during the reaction time.

[0057] Specifically, an inert gas is added together with hydrogen to adjust the reaction pressure within the range of 5 to 50 bar. Maintaining the reaction pressure at a high level so that it is greater than 50 bar is inefficient compared to the facility investment. Therefore, it is not preferred.

[0058] As described above, by adding hydrogen and an inert gas together and applying a pressure higher than the vapor-liquid equilibrium pressure at the corresponding polymerization temperature, the activity of the polymerization reaction can be significantly increased. Any gas that does not affect the polymerization reaction can be used as the inert gas. Specifically, one or more selected from nitrogen, helium, and argon can be used as the inert gas.

[0059] In the preparation method of the present invention, as Figure 1 shown, the method can be carried out by connecting an ethylene gas supply part with an opening and closing device to the reactor of the existing olefin homopolymer preparation device ( Figure 1 (a)). Figure 1 The method can be carried out by connecting an ethylene gas supply part with an opening and closing device to the reactor of the existing olefin homopolymer preparation device (

[0060] Therefore, the preparation method of the present invention does not require an additional polymerization device, and a polybutene elastomer copolymer can be produced by using a device in which an ethylene gas supply part with an opening and closing device is connected to the reactor of the existing olefin homopolymer preparation device ( Figure 1 (a)). Figure 1 The method can be carried out by connecting an ethylene gas supply part with an opening and closing device to the reactor of the existing olefin homopolymer preparation device (

[0061] In addition, when the opening and closing device of the ethylene gas supply part with the opening and closing device is closed, polymers such as olefin homopolymers can be produced by the existing device, so the device can be used efficiently.

[0062] In addition, the present invention relates to a polyolefin elastomer copolymer obtained by copolymerizing ethylene and an olefin by the above method.

[0063] The polyolefin elastomer copolymer has low density, high elasticity, and excellent processability, and thus can be very effectively used in the entire industry. In particular, it can be effectively used for automotive interior and exterior decoration materials, shoes, or cable covering materials.

[0064] Embodiments

[0065] Hereinafter, in order to help understand the present invention, preferred embodiments are presented. However, the following embodiments are only examples to illustrate the present invention. For those skilled in the art, various changes and modifications can obviously be made within the scope and technical idea of the present invention, and these changes and modifications should also belong to the scope of the appended claims.

[0066] Examples:

[0067] Example 1: Preparation of Polyolefin Elastomer Copolymer

[0068] For a 1.5 L stainless steel autoclave, it was purged thoroughly with nitrogen to remove oxygen and moisture that might act as catalyst poisons. 700 mL of liquid-phase 1-butene was added to the reactor as the reaction substance.

[0069] In a catalyst system, (A) a catalyst in which a titanium (Ti) active metal is supported on a magnesium chloride (MgCl₂) carrier is used as a Ziegler-Natta type main catalyst, (B) triethylaluminum (AlCl₃) is used as an aluminum-based cocatalyst, and (C) diisopropylmethoxysilane is used as a silane-based cocatalyst. In terms of catalyst content, specifically, based on 1 mol of the 1-butene monomer, the titanium supported on the magnesium chloride (MgCl₂) carrier is quantified (14 mg is used) to be 2 micromoles (μmol), and the main catalyst is prepared by diluting it to 1 wt% in hexane. Based on 1 mol of titanium contained in the main catalyst, 60 mg of triethylaluminum and 2 mg of diisopropylmethoxysilane are respectively prepared, so that the aluminum-based cocatalyst and the silane-based cocatalyst reach 500 mol and 20 mol respectively. In this way, the molar ratio of the aluminum-based cocatalyst / silane-based cocatalyst is quantified to be 25.

[0070] The prepared aluminum-based cocatalyst is dispersed in hexane to 5 wt% before use, and the silane-based cocatalyst is dispersed in hexane to 2 wt% and then put into an autoclave reactor together with the 1-butene monomer.

[0071] After adding 1-butene, the aluminum-based cocatalyst, and the silane-based cocatalyst, 20 mmol of hydrogen is added per 1 mol of 1-butene. Then, ethylene gas is added until the reactor pressure reaches 1.8 MPa.

[0072] Using a mechanical stirrer, at room temperature, the reactants are stirred at a speed of 150 rpm for about 5 minutes, and the internal temperature of the reactor is raised from room temperature to 60 °C.

[0073] Then, the prepared main catalyst is added to the reactor. Under the condition that the internal pressure of the reactor is pressurized to 1.7 MPa, a polymerization reaction is carried out at a polymerization temperature of 60 °C for 51 min. After the polymerization is completed, 10 mL of ethanol is added and stirred for 5 minutes to terminate the reaction, and the unreacted ethylene and 1-butene are removed. The polymerized polyolefin elastomer is recovered from the autoclave and vacuum dried at 70 °C for 2 hours, thus obtaining 405 g of a polybutene elastomer copolymer.

[0074] Examples 2 and 3: Preparation of Polyolefin Elastomer Copolymer

[0075] For a 1.5 L stainless steel autoclave, it is thoroughly purged with nitrogen to remove oxygen and moisture that may have an impact as catalyst poisons. 700 mL of liquid-phase 1-butene is added to the reactor as a reaction substance.

[0076] In a catalyst system, (A) a catalyst in which a titanium (Ti) active metal is supported on a magnesium chloride (MgCl₂) carrier is used as a Ziegler-Natta type main catalyst, (B) triethylaluminum (AlCl₃) is used as an aluminum-based cocatalyst, and (C) diisopropylmethoxysilane is used as a silane-based cocatalyst. In terms of catalyst content, specifically, based on 1 mol of the 1-butene monomer, the titanium supported on the magnesium chloride (MgCl₂) carrier is quantified (14 mg is used) to be 2.0 micromoles (μmol), and it is diluted to 1 wt% in hexane to prepare the main catalyst. Based on 1 mol content of titanium contained in the main catalyst, 60 mg of triethylaluminum and 2 mg of diisopropylmethoxysilane are respectively prepared, so that the aluminum-based cocatalyst and the silane-based cocatalyst reach 500 mol and 20 mol respectively. In this way, the molar ratio of the aluminum-based cocatalyst / silane-based cocatalyst is quantified to be 25.

[0077] The prepared aluminum-based cocatalyst is dispersed in hexane to 5 wt% before use, and the silane-based cocatalyst is dispersed in hexane to 2 wt% and then put into an autoclave reactor together with the 1-butene monomer.

[0078] After adding 1-butene, the aluminum-based cocatalyst, and the silane-based cocatalyst, 150 mmol of hydrogen is added relative to each 1 mol of 1-butene. Then, the above-prepared main catalyst is added to the inside of the reactor. Using a mechanical stirrer, the reactants are stirred at a speed of 150 rpm at room temperature for about 5 minutes, and the temperature inside the reactor is raised from room temperature to 60 °C. After the internal temperature reaches 60 °C, ethylene gas is further supplied during the polymerization reaction to keep the pressure inside the reactor at 1.8 MPa. At a polymerization temperature of 60 °C, a polymerization reaction is carried out for 35 minutes. After the polymerization is completed, 10 mL of ethanol is added and stirred for 5 minutes to terminate the reaction, and unreacted ethylene and 1-butene are removed, and the polymerized polyolefin elastomer is recovered from the autoclave and vacuum-dried at 70 °C for 2 hours, thereby obtaining 237 g of a polyolefin elastomer copolymer.

[0079] It is carried out in the same manner as in Example 2, and according to the conditions in Table 1 below, the amount of hydrogen, the amount of nitrogen, and the reaction time are changed to prepare the polyolefin elastomer copolymer of Example 3.

[0080] Table 1:

[0081]

[0082] Experimental example: Evaluation of the physical properties of the copolymer

[0083] For the polymers prepared through the above Examples 1 to 3 and the Engrade 7467 product of the polyolefin elastomer commercially available from The Dow Chemical Company, according to the following evaluation methods, the physical properties were measured, and the results are shown in Table 2 below.

[0084] <Evaluation Methods for Physical Properties of Polymers>

[0085] (1) Activity (kg polymer / g catalyst·hour): The amount of polyolefin elastomer produced per unit catalyst and reaction time

[0086] Amount of polymer produced / (amount of catalyst used × reaction time)

[0087] (2) Melt Flow Index (MFR): ASTM D1238

[0088] (3) Density: ASTM D1505

[0089] (4) Number-average molecular weight (Mn) and molecular weight distribution (Mw / Mn): Measured by GPC

[0090] (5) C4 content: Measured by C 13 NMR

[0091] (6) Melting Temperature: Measured by differential scanning calorimetry (DSC, Differential Scanning Calorimeter)

[0092] Table 2:

[0093]

[0094] It can be confirmed from Table 2 above that the 1-butene content in the polyolefin elastomers prepared through Examples 1 to 3 of the present invention can be adjusted to various contents by operating conditions. Additionally, as Figure 2 shown, compared with commercially available products, low-density polyolefin elastomers can be manufactured, thereby providing end products with excellent elasticity. Additionally, as Figure 3 shown, polyolefin elastomers with a molecular weight distribution (Mn / Mw) up to more than twice that of commercial products prepared with metallocene catalysts can be manufactured, and thus excellent processability can be provided.

Claims

1. A method for preparing a polyolefin elastomer copolymer, characterized in that, It includes the following steps: (a) Adding a liquid olefin monomer selected from 1-butene monomer, 1-hexene monomer, and 1-octene monomer, ethylene gas, and a titanium-supported Ziegler-Natta catalyst into the reactor; and (b) Conducting a polymerization reaction at 50 to 70 °C, wherein, in the step (a), relative to every 1 mol of the olefin monomer, 1 to 200 mmol of hydrogen is further added into the reactor, and nitrogen is further added into the reactor together with the hydrogen to adjust the reaction pressure within the range of 5 to 50 bar.

2. The method for preparing a polyolefin elastomer copolymer according to claim 1, wherein in the step (a), either ethylene gas or the titanium-supported Ziegler-Natta catalyst is added first, and after the temperature of the reactor is raised to 50 to 70 °C, the other one is added.

3. The method for preparing a polyolefin elastomer copolymer according to claim 1, wherein the titanium-supported Ziegler-Natta catalyst is added to make the titanium content reach 0.5 to 3.0 μmol based on 1 mol of the olefin monomer; ethylene gas is supplied at 0.1 to 2.0 MPa during the reaction.

4. The method for preparing a polyolefin elastomer copolymer according to claim 3, wherein in the step (a), relative to every 1 mol content of titanium, 50 to 700 mol of an aluminum-based cocatalyst and 1 to 100 mol of a silane-based cocatalyst are further added.

5. The method for preparing a polyolefin elastomer copolymer according to claim 4, wherein the molar ratio of the aluminum-based cocatalyst to the silane-based cocatalyst is 10 to 30:

1.

6. The method for preparing a polyolefin elastomer copolymer according to claim 1, wherein the polymerization reaction in the step (b) is carried out for 0.5 to 3 hours.

7. The method for preparing a polyolefin elastomer copolymer according to claim 1, wherein the method is carried out by connecting an ethylene gas supply part with an opening and closing device to the reactor of an olefin homopolymer preparation device.

8. A polyolefin elastomer copolymer, characterized in that ， Prepared by the method according to claim 1.

9. The polyolefin elastomer copolymer according to claim 8, wherein the polyolefin elastomer copolymer is used for automotive interior and exterior decoration materials, shoes, or cable covering materials.

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