Method for preparing EPDM copolymer

Abstract

The invention relates to a method for preparing an EPDM (ethylene-propylene-diene monomer) copolymer. Specifically, the present invention relates to a method for preparing an EPDM copolymer by solution polymerization using a Ziegler-Natta catalyst system, and to a method for preparing an EPDM copolymer which suppresses an ultra-high molecular weight reaction of an EPDM polymer in solution polymerization and has a narrow molecular weight distribution. In addition, the present invention relates to an EPDM copolymer prepared by the method for preparing the EPDM copolymer according to one embodiment of the present invention, and a composite composition using the same. The composite composition according to one embodiment of the present invention can be used in the field where low compression set rates are required at normal and high temperatures.

Description

Technical Field

[0001] The present invention relates to a method for preparing an EPDM copolymer. More specifically, the present invention relates to a method for preparing an EPDM copolymer by solution polymerization using a Ziegler-Natta catalyst system, and in particular, to a method for preparing an EPDM copolymer with a narrow molecular weight distribution. Background Art

[0002] EPDM copolymer is a polymer prepared from ethylene, propylene, and a diene comonomer, wherein the diene uses ethylidene norbornene (ENB), dicyclopentadiene (DCPD), and vinyl norbornene (VNB).

[0003] EPDM copolymer is a vulcanizable copolymer that exhibits excellent physical properties such as weather resistance, heat resistance, and ozone resistance, and can be used in various rubber products, such as automotive parts, industrial rubber products, electrical insulation materials, civil engineering materials, construction materials, etc.

[0004] In order to be applied to weather strips and seals in automobile parts, low compression set characteristics at room temperature and high temperature are required. For this purpose, although the formula of the composite composition is adjusted and used, the most important thing is the influence of the molecular structure of the EPDM copolymer as a raw material, that is, the influence of the molecular weight distribution. In order to reduce the compression set, it is necessary to narrow the molecular weight distribution of the EPDM copolymer.

[0005] Generally, when a solution polymerization is performed using a Ziegler-Natta catalyst system, a coupling reaction between 5-ethylidene-2-norbornene (ENB) may occur, and thus a polymer having a weight average molecular weight including an ultra-high molecular weight may be generated. Although not limited thereto, the ultra-high molecular weight in the present invention may be a weight average molecular weight of 1,000,000 g / mol or more based on polystyrene in a gel permeation chromatography (GPC) analysis.

[0006] When a polymer having a weight average molecular weight of an ultrahigh molecular weight thus produced is compounded, the compression set characteristic cannot be satisfied and the surface roughness of the product increases.

[0007] Therefore, there is a need for an EPDM copolymer having a reduced content of such ultra-high molecular weight and having a narrow molecular weight distribution.

[0008] [Prior art literature]

[0009] [Patent Document]

[0010] Korean Patent No. 10-2019825 (September 3, 2019) Summary of the invention

[0011] Technical issues to be solved

[0012] A technical problem of the present invention is to provide an EPDM copolymer having a narrow molecular weight distribution and capable of reducing the compression set rate when preparing a composite composition, and a preparation method thereof, by controlling the ultrahigh molecular weight reaction generated during the polymerization of EPDM.

[0013] In addition, the present invention provides an EPDM copolymer that can provide low compression set when preparing a composite composition, specifically, can provide low compression set after being kept at 70° C. for 72 hours according to ASTM D-395, and a preparation method thereof.

[0014] Technical Solution

[0015] In one embodiment of the present invention, as a result of studies to narrow the molecular weight distribution of EPDM, it was found that by controlling the ultrahigh molecular weight formation reaction, a narrower molecular weight distribution can be provided, and even in the same molecular weight distribution, an EPDM copolymer with a lower ultrahigh molecular weight content can be provided.

[0016] When EPDM is prepared by solution polymerization using a Ziegler-Natta catalyst, it is presumed that due to the acidic catalyst and co-catalyst, 5-ethylidene-2-norbornene (ENB) between EPDM molecules generates positive ions, which react with ENB of other molecules to generate macromolecules. That is, the EPDM coupling reaction proceeds in the polymerization system through the ENB coupling reaction, thereby generating an ultra-high molecular weight tail.

[0017] In one embodiment of the present invention, a catalyst system of a specific combination is developed to prevent ENB cations from reacting with ENB of other molecules, and by providing a method for preparing an EPDM copolymer using the catalyst system of the present invention and in a specific addition order, it is confirmed that an EPDM copolymer having a desired narrow molecular weight distribution and a lower ultra-high molecular weight content can be provided.

[0018] One embodiment of the present invention provides a method for preparing EPDM copolymers, which is a solution polymerization preparation method of ethylene-propylene-diene (EPDM) copolymers using a Ziegler-Natta catalyst system, wherein the Ziegler-Natta catalyst system comprises VOCl3, ethylaluminum sesquichloride (EASC) and a linear or branched C4-C6 alkylamine as a catalyst modifier, and includes a polymerization step of adding the catalyst modifier before injecting VOCl3 or adding VOCl3 and the catalyst modifier simultaneously to carry out polymerization.

[0019] As an embodiment, the molecular weight distribution (Mw / Mn) of the EPDM copolymer may be 5 or less, or 2 to 3, and the residual vanadium content may be 20 ppm or less, but is not limited thereto.

[0020] As an embodiment, the weight average molecular weight of the EPDM copolymer may be 200,000-400,000 g / mol, but is not limited thereto.

[0021] As an embodiment, the content of the catalyst modifier may be 0.25 mol to 1 mol relative to 1 mol of VOCl 3 , but is not limited thereto.

[0022] As an embodiment, the content of the catalyst modifier may be 0.5 to 1 mole ratio relative to 1 mole of VOCl 3 , but is not limited thereto.

[0023] As an embodiment, the catalyst modifier may be n-butylamine, but is not limited thereto.

[0024] As an embodiment, the preparation method can be prepared by a batch or continuous polymerization method.

[0025] As an embodiment, the solvent used in the solution polymerization reaction may be a hydrocarbon solvent, but is not limited thereto. For example, the hydrocarbon solvent may be any one or a mixture of two or more selected from pentane, hexane, heptane and octane, but is not limited thereto.

[0026] As an embodiment, the polymerization step may be performed at 30-50° C., but is not limited thereto.

[0027] As an embodiment, in the polymerization step, the content ratio of propylene, ethylene and 5-ethylidene-2-norbornene (ENB) may be propylene: 20-40 wt%, ethylene: 50-70 wt% and 5-ethylidene-2-norbornene (ENB): 5-10 wt%, but is not limited thereto.

[0028] Another embodiment of the present invention provides an EPDM copolymer prepared by the preparation method according to the one embodiment.

[0029] Another embodiment of the present invention provides a composite composition including an EPDM copolymer prepared by the preparation method according to the one embodiment.

[0030] As one embodiment, the composite composition may have a compression set of 50% or less when the composite composition is kept at 120° C. and compressed to 25% for 22 hours according to ASTM D-395.

[0031] Beneficial Effects

[0032] The method for preparing an EPDM copolymer according to one embodiment of the present invention has the effect of suppressing an ultrahigh molecular weight reaction of an EPDM polymer in a solution polymerization process using a Ziegler-Natta catalyst system and can provide an EPDM copolymer having a narrow molecular weight distribution.

[0033] The EPDM copolymer prepared according to one embodiment of the present invention has a narrow molecular weight distribution and suppresses the generation of ultra-high molecular weight terminals on GPC, thereby providing an EPDM copolymer having a reduced peak of ultra-high molecular weight terminals on GPC.

[0034] Furthermore, the composite composition using the EPDM copolymer prepared according to one embodiment of the present invention has an effect of reducing the compression set rate.

[0035] In addition, the EPDM copolymer prepared according to one embodiment of the present invention and the composite composition using the EPDM copolymer can be applied to fields requiring low compression set at room and high temperatures, such as automotive weather strips and seals. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The graphs show GPC differential molecular weight distribution curves of EPDM polymers (Examples 1 to 3) and comparative examples produced when EPDM polymerization is carried out by premixing a catalyst modifier (n-BA) and a catalyst and then adding the mixture.

[0037] Figure 2 The graphs show GPC differential molecular weight distribution curves of EPDM polymers (Examples 4 to 6) produced when the catalyst modifier (n-BA) and the catalyst are added to a reactor for polymerization without premixing and comparative examples. DETAILED DESCRIPTION

[0038] The present invention will be described in more detail below. However, the following specific embodiments or examples are only a reference for describing the present invention in detail, and the present invention is not limited thereto, and the present invention can be implemented through various embodiments.

[0039] In addition, unless otherwise defined, all technical terms and scientific terms have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. The terms used in the description of the present invention are only used to effectively describe specific embodiments and are not intended to limit the present invention.

[0040] Furthermore, unless otherwise specifically stated, singular forms used in the specification and claims also include plural forms.

[0041] In addition, unless otherwise specifically described to the contrary, the description that a part “includes” or “comprises” a certain constituent element means that other constituent elements may also be included, rather than excluding other constituent elements.

[0042] In addition, the terms "about", "substantially", etc. used in the present invention are used in the sense of that value or close to that value when the allowable errors of manufacturing and materials inherent in the meaning mentioned are proposed, and in order to assist in understanding the present invention, the said "about", "substantially", etc. are used to prevent unscrupulous infringers from unfairly using the disclosure mentioned in the exact or absolute numerical value.

[0043] The present inventors have conducted research to control the ultrahigh molecular weight reaction of the polymer in the EPDM polymerization reaction and to prepare an EPDM copolymer with a narrow molecular weight distribution. As a result, they have found that the above-mentioned purpose can be achieved by preparing the EPDM copolymer by solution polymerization using a specific combination of reaction systems based on a Ziegler-Natta catalyst, thereby completing the present invention.

[0044] Furthermore, the present inventors have found that when solution polymerization is carried out using the Ziegler-Natta catalyst system of the specific combination, the above-mentioned object can be achieved by carrying out polymerization by adjusting the order of adding the specific catalyst and the catalyst modifier, thereby completing the present invention.

[0045] Furthermore, the present inventors have found that, when a specific molecular weight distribution (Mw / Mn) is satisfied, the compression set rate can be further improved when preparing a composite composition, thereby completing the present invention.

[0046] One embodiment of the present invention provides a method for preparing EPDM copolymers, which is a solution polymerization preparation method of ethylene-propylene-diene (EPDM) copolymers using a Ziegler-Natta catalyst system, wherein the Ziegler-Natta catalyst system comprises VOCl3, ethylaluminum sesquichloride (EASC) and a linear or branched C4-C6 alkylamine as a catalyst modifier, and includes a polymerization step of adding the catalyst modifier before injecting VOCl3 or adding VOCl3 and the catalyst modifier simultaneously to carry out polymerization.

[0047] The simultaneous addition of the VOCl 3 and the catalyst modifier includes adding them separately to their respective addition ports, or premixing the VOCl 3 and the catalyst modifier and adding them in the form of a mixture.

[0048] The molecular weight distribution (Mw / Mn) of the EPDM copolymer prepared according to one embodiment may be 5 or less, 4 or less, or 3 or less. Although not limited thereto, the molecular weight distribution is 3 or less, for example, in the range of 2 to 3, because the compression set rate can be further reduced when preparing a composite composition for automotive weather strips, seals, etc., and is therefore preferred, but not limited thereto. For example, the following physical properties may be satisfied, and the compression set rate after being kept for 22 hours at a temperature of 120° C. and compressed to 25% according to ASTM D-395 is 50% or less, 49% or less, 48% or less, or 47% or less.

[0049] In addition, the content of residual vanadium can be 30ppm or less, 25ppm or less, 20ppm or less, 19ppm or less, 18ppm or less, 17ppm or less, 16ppm or less, 15ppm or less, 14ppm or less, 13ppm or less, 12ppm or less, 11ppm or less, 10ppm or less, 9ppm or less, 8ppm or less, 7ppm or less, or any value between the values. When the content of residual vanadium in the polymer prepared by the preparation method exceeds 30ppm, yellowing phenomenon of product discoloration may occur, and when preparing a composite composition, it may be difficult to achieve a low compression set rate. More specifically, the content of residual vanadium can be 1-30ppm, 1-25ppm, 1-20ppm, 1-17ppm, 1-16ppm, 1-15ppm, 1-14ppm, 1-13ppm, 1-12ppm, 1-11ppm, 1-10ppm, 1-9ppm, 1-8ppm, 1-7ppm.

[0050] As described above, the present invention uses a specific component in combination through a Ziegler-Natta catalyst system, and thus can provide an EPDM copolymer having a molecular weight distribution (Mw / Mn) of 5 or less or 3 or less and a residual vanadium content of 30 ppm or less. In addition, the EPDM copolymer prepared according to one embodiment may contain an ultra-high molecular weight polymer having a weight average molecular weight of 1,000,000 or more measured by a GPC method in an amount of 1% or less.

[0051] As an implementation scheme, Figure 1 and Figure 2 As shown, an EPDM copolymer showing a narrower molecular weight distribution at the same weight average molecular weight can be provided, compared with an EPDM polymer polymerized without using a catalyst modifier or using a Ziegler-Natta catalyst system using other compounds instead of a Ziegler-Natta catalyst system using a linear or branched C4-C6 alkylamine.

[0052] As an implementation scheme, Figure 1 and Figure 2 As shown, the following EPDM copolymer can be provided: in a differential molecular weight distribution curve in which the horizontal axis is the logarithmic value log(M) of the molecular weight M and the vertical axis is dw / dlog(M) which is the derivative of the concentration fraction w divided by the logarithmic value log(M) of the molecular weight, in the ultra-high molecular weight range where log(M) is 6 to 7, the value of dw / dlog(M) shows a relatively low value.

[0053] Hereinafter, the method for preparing the EPDM copolymer of the present invention will be described in more detail.

[0054] The preparation method according to one embodiment of the present invention may be prepared by a batch-type or continuous-type polymerization method.

[0055] As an embodiment, the method for preparing by batch mode is described as follows, and the method may include the following steps:

[0056] a) a preparation step of adding a hydrocarbon-based solvent, ethylaluminum sesquichloride (EASC), propylene, ethylene and 5-ethylidene-2-norbornene (ENB) into a reactor and stirring; and

[0057] b) a polymerization step, adding VOCl3 and a linear or branched C4-C6 alkylamine as a catalyst modifier into the reactor for reaction, wherein the catalyst modifier is added before injecting VOCl3, or VOCl3 and the catalyst modifier are added into the reactor simultaneously.

[0058] In the case of the batch polymerization method, in order to remove impurities in the solvent, ethylaluminum sesquichloride (EASC) may be added first and then VOCl 3 and the catalyst modifier may be added, but is not limited thereto.

[0059] Therefore, the batch polymerization process may comprise the following steps:

[0060] a) a preparation step of adding a hydrocarbon-based solvent, propylene, ethylene and 5-ethylidene-2-norbornene (ENB) into a reactor and stirring; and

[0061] b) a polymerization step, adding ethylaluminum sesquichloride (EASC), VOCl3 and a linear or branched C4-C6 alkylamine as a catalyst modifier into a reactor for reaction, wherein the catalyst modifier is added before injecting VOCl3, or VOCl3 and the catalyst modifier are added into the reactor simultaneously.

[0062] As an embodiment, in the case of preparation by a continuous polymerization method, it can include a polymerization step of continuously adding a hydrocarbon solvent, propylene, ethylene and 5-ethylidene-2-norbornene (ENB) into a reactor, and adding ethylaluminum sesquichloride (EASC) as a catalyst, VOCl3 and a linear or branched C4-C6 alkylamine as a catalyst modifier for reaction, wherein the catalyst modifier is added before injecting VOCl3, or VOCl3 and the catalyst modifier are added to the reactor separately.

[0063] As an embodiment, the polymerization step may be performed at 30-50° C. More specifically, the process of adding a hydrocarbon-based solvent, propylene, ethylene, and 5-ethylidene-2-norbornene (ENB) in a reactor may be performed at 30-35° C., in the process of adding the Ziegler-Natta catalyst system of the present invention, the initial temperature may be performed at 30-35° C., and the polymerization may be performed at 35-50° C. after the Ziegler-Natta catalyst system is added. Within the above range, side reactions and yellowing of the generated polymer may be reduced, so it is preferred, but not limited thereto.

[0064] As an embodiment, when adding the catalyst, the catalyst modifier can be added before injecting VOCl3, or VOCl3 and the catalyst modifier can be added to the reactor at the same time for reaction. Although not limited to this, by reacting in the order of addition as described above, an EPDM copolymer with desired physical properties can be prepared.

[0065] As an embodiment, the hydrocarbon-based solvent may be any one or more solvents selected from pentane, hexane, heptane and octane, and more preferably may be hexane. In addition, the hydrocarbon-based solvent may include a solvent that is recycled after being recovered and purified after the polymerization step, but is not limited thereto.

[0066] As an embodiment, the Ziegler-Natta catalyst system comprises a co-catalyst to improve the catalytic efficiency of VOCl3, and the co-catalyst comprises ethylaluminum sesquichloride (EASC). In addition, as required, other types of co-catalysts other than the ethylaluminum sesquichloride (EASC) can be further used.

[0067] Specifically, trialkylaluminums such as trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, trioctylaluminum, and tri(2-ethylhexyl)aluminum can be used; alkenylaluminums such as isoprenealuminum; dialkylaluminum halides such as dimethylaluminum chloride, diethylaluminum chloride, diisopropylaluminum chloride, diisobutylaluminum chloride, and dimethylaluminum bromide; alkylaluminum sesquihalides such as methylaluminum sesquichloride, isopropylaluminum sesquichloride, butylaluminum sesquichloride, and ethylaluminum sesquibromide; alkylaluminum dihalides such as methylaluminum dichloride, ethylaluminum dichloride, isopropylaluminum dichloride, and ethylaluminum dibromide; alkylaluminum hydrides such as diethylaluminum hydride and diisobutylaluminum hydride, etc. can be used.

[0068] As described above, when a vanadium catalyst and an acidic ethylaluminum sesquichloride (EASC) co-catalyst are included for polymerization, a coupling reaction between 5-ethylidene-2-norbornene (ENB) may be induced in the polymerization step due to the acidic reaction atmosphere. Therefore, the ultrahigh molecular weight is increased, thereby increasing the compression set rate during compounding.

[0069] However, as described above, the present invention performs polymerization by adding a linear or branched C4-C6 alkylamine as a catalyst modifier to the catalyst system, thereby suppressing the coupling reaction.

[0070] As an embodiment, the straight or branched C4-C6 alkylamine as the catalyst modifier can be a primary amine, a secondary amine and a tertiary amine compound. Its type can use, for example, n-butylamine, dibutylamine, tert-butylamine, amylamine, hexylamine, etc. In the case where the carbon number of the alkyl group is less than 4 or ammonia, the boiling point (bp) is low and the solubility in the hydrocarbon-based solvent as the reaction solvent is low, so that it is separated into the gas phase (gas phase) at the upper end of the reactor, and in fact, it is almost non-existent in the liquid phase (liquid phase) at the lower end of the reactor of the polymerization EPDM, so the participation efficiency of the desired ultra-high molecular weight generation inhibition reaction is low. In addition, in the case where the carbon number of the alkyl group exceeds 6, the ultra-high molecular weight inhibition effect can be maintained, but the catalyst is not removed after the polymerization reaction, and the residual catalyst in the product may eventually cause serious side effects of inducing discoloration, so there may be limitations when applied in the product. In addition, excessive residual catalysts can accelerate the decomposition reaction of EPDM and may cause a reduction in physical properties. Although not limited thereto, the catalyst modifier may be n-butylamine. Compared with other alkylamines, n-butylamine can achieve a more excellent effect and is therefore preferred, but not limited thereto.

[0071] In the present invention, a linear or branched C4-C6 alkylamine is used in an in-situ method to inhibit the coupling reaction between 5-ethylidene-2-norbornene (ENB) that occurs when a catalyst combination of VOCl3 and ethylaluminum sesquichloride (EASC) is polymerized under acidic conditions, thereby inhibiting the generation of ultrahigh molecular weight. In addition, an EPDM copolymer having a narrow molecular weight distribution, specifically, a molecular weight distribution of 5 or less or 3 or less can be provided, and since the content of residual vanadium after polymerization is low, an EPDM copolymer that does not discolor can be provided.

[0072] As an embodiment, the content of the catalyst modifier can be 0.25 molar ratio to 1 molar ratio, or 0.5 molar ratio to 1 molar ratio relative to VOCl3. When the content of the catalyst modifier is 0.5 molar ratio to 1 molar ratio, a polymer with a lower molecular weight distribution can be prepared, for example, a polymer with a molecular weight distribution of less than 3 or 2 to 3 can be prepared. In addition, it may be beneficial to prepare an EPDM copolymer with a residual vanadium content of less than 20ppm. When the content of the catalyst modifier exceeds 1 molar ratio, the toxicity of the catalyst is aggravated, which may reduce the activity of the catalyst.

[0073] As an embodiment, the molar ratio Al / V of aluminum of the ethylaluminum sesquichloride (EASC) to vanadium of VOCl3 may be 3 to 8. Although not limited thereto, within the above range, the catalyst has excellent activity, so the polymerization yield can be further improved, and an EPDM copolymer having a molecular weight distribution (Mw / Mn) of 3 or less and a residual vanadium content of 20 ppm or less can be prepared.

[0074] As an embodiment, the content ratio of propylene, ethylene and 5-ethylidene-2-norbornene (ENB) may be propylene: 20-40 wt%, ethylene: 50-70 wt% and 5-ethylidene-2-norbornene (ENB): 5-10 wt%, although not limited thereto. However, within the above range, the physical properties required for manufacturing a weather strip for an automobile can be provided.

[0075] As an embodiment, the weight average molecular weight of the EPDM copolymer may be 200,000-400,000 g / mol. Within the above range, the physical properties required for manufacturing a weather strip for automobiles can be provided, and thus it is preferred, but not limited thereto.

[0076] As an embodiment, it can be confirmed that the content of ultra-high molecular weight polymer having a weight average molecular weight of 1,000,000 g / mol or more in the EPDM copolymer prepared according to the preparation method of the present invention is reduced compared with the EPDM copolymer having the same molecular weight distribution. Figure 1 and Figure 2 In explanation, it can be confirmed that the horizontal axis, which is the logarithmic value of the molecular weight M, log (M), represents about 6, which is 1,000,000 g / mol, and the graphs of Examples 1 to 6 show lower molecular weights than Comparative Example 1. It can be confirmed that a polymer having a narrow molecular weight distribution and a lower content of ultrahigh molecular weight can be provided.

[0077] As an embodiment, the composite composition of the EPDM copolymer prepared by the preparation method of the present invention can satisfy the following physical properties: the compression set rate after being kept at 120° C. and compressed to 25% for 22 hours according to ASTM D-395 is 50% or less.

[0078] Furthermore, the EPDM copolymer prepared by the preparation method according to the present invention can provide a composite composition having a lower compression set rate than a composite composition of an EPDM copolymer prepared by changing the type of vanadium catalyst or without using the catalyst modifier of the present invention.

[0079] As an example, the composite composition may be prepared by mixing the EPDM copolymer prepared according to the preparation method of the present invention, carbon black, additives, and the like.

[0080] Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples. However, the following Examples and Comparative Examples are merely examples for describing the present invention in more detail, and the present invention is not limited to the following Examples and Comparative Examples.

[0081] The following physical properties were measured as follows.

[0082] 1. Measurement methods of weight average molecular weight (Mw), z average molecular weight (Mz), molecular weight distribution (Mw / Mn, MWD) and ultra-high molecular weight

[0083] The measurements were performed using gel permeation chromatography.

[0084] Agilent 1260 Infinity II gel permeation chromatograph (GPC) was used.

[0085] -Chromatographic column: Graphite column

[0086] -Solvent: Trichlorobenzene (TCB)

[0087] -Flow rate: 1.0ml / min

[0088] -Sample concentration: 1.0mg / ml

[0089] -Injection volume: 200μm

[0090] - Column temperature: 160°C

[0091] -Detector: IR5 detector

[0092] -Standard: Polystyrene (calibrated with cubic function)

[0093] 2. Measurement method of residual vanadium content

[0094] Take 0.1g of the sample into a platinum crucible, then add sulfuric acid and heat to carbonize it. After carbonization is completed, cool to room temperature and then ash in an electric furnace at 250°C and 600°C in two stages. After ashing, cool to room temperature, then add nitric acid and heat to dissolve the residue. Stop heating when dissolution is complete and dilute 10mL with ultrapure water. When the sample solution is introduced into an inductively coupled plasma analyzer (ICP), the metal component is ionized by a plasma of about 6000K, and the ionized elements are separated according to the mass-to-charge ratio (m / z) to obtain a mass spectrum and the intensity of the mass spectrum to perform qualitative and quantitative analysis of each vanadium element.

[0095] 3. Compression permanent deformation rate

[0096] The compression set rate was measured by setting the temperature to 120° C. and holding a test piece having a height of 12.5 mm in a state of being compressed to 25% for 22 hours in accordance with ASTM D-395.

[0097] The compression set rate is an evaluation of the degree to which a rubber material recovers over time when compressed by external pressure. It is an important indicator for understanding the physical properties of rubber materials.

[0098] Compression set rate = initial height of the test piece - height of the test piece after compression / initial height of the test piece × 100

[0099] [Example 1]

[0100] The EPDM polymerization reaction was carried out by batch polymerization. The solvent and ethylene, propylene, and 5-ethylidene-2-norbornene (ENB) used in the polymerization reaction were purified by column purification before use. The 3L reactor was formed into an inert reactor atmosphere by flushing with solvent at high temperature and using purified nitrogen. 851g of hexane was added to the reactor, and 0.69g of ethyl aluminum sesquichloride (EASC), 42000cc of propylene, 15000cc of ethylene, and 3g of 5-ethylidene-2-norbornene (ENB) were added, and then stirred at 250rpm and the temperature of the reactor was maintained at 30°C. 0.115g of VOCl3 and n-butylamine were premixed for 1 minute with the contents described in Table 1 below, and the mixture was added to the reactor for EPDM polymerization. The polymerization reaction was started at 30°C, and the reaction was carried out for 10 minutes after the temperature was raised to 40°C. The physical properties of the obtained polymer were evaluated and are shown in Table 1 below.

[0101] [Example 2 to Example 3]

[0102] EPDM polymerization was carried out by the same method as in Example 1, except that the content of n-butylamine was changed as shown in the following Table 1. The physical properties of the obtained polymer were evaluated and are shown in the following Table 1.

[0103] [Example 4 to Example 6]

[0104] The EPDM polymerization reaction was carried out in the same manner as in Example 1, except that the n-butylamine and VOCl3 were added sequentially as described below without premixing.

[0105] That is, hexane was added to the reactor, and ethylaluminum sesquichloride (EASC), n-butylamine, propylene, ethylene and 5-ethylidene-2-norbornene (ENB) were added in the contents described in Table 1 below, and then stirred at 250 rpm and the temperature of the reactor was maintained at 30° C. VOCl3 was added to the reactor in the contents described in Table 1 below to carry out EPDM polymerization. The polymerization reaction was started at 30° C., and the temperature was raised to 40° C. and the reaction was carried out for 10 minutes. The physical properties of the obtained polymer were evaluated and are shown in Table 1 below.

[0106] [Example 7 to Example 11]

[0107] EPDM polymerization was carried out in the same manner as in Example 1, except that the type of catalyst modifier was changed to the type described in Table 1 instead of n-butylamine. Physical properties of the obtained polymer were evaluated and are shown in Table 1 below.

[0108] [Example 12]

[0109] The EPDM polymerization reaction was carried out by continuous polymerization. The solvent and ethylene, propylene, and 5-ethylidene-2-norbornene (ENB) used in the polymerization reaction were purified by column purification before use. Hexane was used as a solvent, and 1370 kg / hour of ethylene, 1500 kg / hour of propylene, and 140 kg / hour of 5-ethylidene-2-norbornene (ENB) were continuously added, and 1.8 kg / hour of VOCl3, 10.8 kg / hour of ethylaluminum sesquichloride (EASC), and 0.6 kg / hour of n-butylamine were continuously added as catalysts for polymerization. The polymerization temperature was maintained at 40°C. n-Butylamine and VOCl3 were added simultaneously, but were added separately through separate addition ports. The obtained polymer was made into EPDM bales by flashing process, catalyst removal process, solvent removal process, drying process, and baling process, and the physical properties of the obtained products were evaluated and shown in Table 1 below.

[0110] [Comparative Example 1]

[0111] As shown in Table 1 below, EPDM polymerization was carried out by the same method as in Example 1, except that n-butylamine was not used. The physical properties of the obtained polymer were evaluated and are shown in Table 1 below.

[0112] [Comparative Example 2 to Comparative Example 3]

[0113] As shown in Table 1 below, EPDM polymerization was carried out in the same manner as in Example 1, except that heptylamine or ammonia was used instead of n-butylamine. Gaseous ammonia was added using a mass flow controller. The physical properties of the obtained polymer were evaluated and are shown in Table 1 below.

[0114] [Comparative Example 4]

[0115] EPDM polymerization was carried out by the same method as in Example 12, except that n-butylamine was not used. Physical properties of the obtained polymer were evaluated and are shown in Table 1 below.

[0116] [Table 1]

[0117]

[0118]

[0119] As shown in Table 1, it can be confirmed that in Examples 1 to 12, as the molar ratio of the amine compound used as a catalyst modifier relative to the vanadium (V) content of the VOCl3 catalyst increases, the molecular weight distribution becomes lower. In addition, it is confirmed that in the range of the molar ratio of the amine compound being 0.5 to 1, the molecular weight distribution becomes lower, and the molecular weight distribution specifically satisfies the physical properties of 2 to 3 and satisfies the physical property that the residual vanadium content is 20 ppm or less.

[0120] In addition, if Figure 1 and Figure 2 As shown, it can be confirmed that the molecular weight distribution of Examples 1 to 6 is lower than that of Comparative Example 1 in which n-butylamine is not used as a catalyst modifier, and the content of ultrahigh molecular weight is further reduced. Specifically, Figure 1 and Figure 2As shown, in the differential molecular weight distribution curve in which the horizontal axis is the logarithmic value log(M) of the molecular weight M and the vertical axis is dw / dlog(M) which is the derivative of the concentration fraction w as the logarithmic value log(M) of the molecular weight, when log(M) is 6, the values ​​of dw / dlog(M) of Examples 1 to 6 show relatively low values ​​compared to Comparative Example 1, and thus it can be confirmed that the content of ultrahigh molecular weight is lower. In addition, it can be confirmed that the value of dw / dlog(M) shows the maximum peak at 5≤log(M)≤6, and the values ​​of dw / dlog(M) of Examples 1 to 6 are larger than those of Comparative Example 1.

[0121] Furthermore, when Example 12 and Comparative Example 4 prepared by continuous polymerization were compared, it was confirmed that the molecular weight distribution of Example 12 using n-butylamine as a catalyst modifier was lower and the content of ultrahigh molecular weight was further reduced.

[0122] In addition, when the comparative example 2 using heptylamine is compared with the examples 2, 5, 8 to 11 using the same amount of C4-C6 alkylamine, it can be confirmed that the ultrahigh molecular weight suppression effect is also achieved in the comparative example 2, but the effect is reduced compared with the other examples, and more importantly, it can be confirmed that the removal efficiency of the polymerization catalyst is reduced, so the content of the residual vanadium catalyst in the polymerized EPDM is greatly increased. In the case where the content of the residual catalyst is increased, the degree of yellowing of the product when it is prepared as a composite composition may increase.

[0123] In addition, as shown in Comparative Example 3, when ammonia is used, it is confirmed that the boiling point (bp) is low and the solubility in hexane is low, so it is separated into the gas phase at the upper end of the reactor and is almost absent in the liquid phase layer at the lower end of the reactor where EPDM is polymerized. Therefore, the efficiency of participating in the desired ultra-high molecular weight generation inhibition reaction is low.

[0124] [Experimental example]

[0125] Composite compositions were prepared using Example 12 and Comparative Example 4 showing similar weight average molecular weights, and the compression set was evaluated.

[0126] The composite composition was prepared as follows: 80 parts by weight of carbon black (N550) was mixed with 100 parts by weight of EPDM of each example and comparative example in a Banbury mixer, and then 5 parts by weight of ZnO, 0.5 parts by weight of 2-mercaptobenzothiazole (MBT), 1.0 parts by weight of tetramethyl thiuram disulfide (TMTD), and 1.5 parts by weight of sulfur were further mixed using a roll mill mixer, and then the composite composition was evaluated according to the compression set evaluation method.

[0127] As a result, the compression set rate of the composite composition using Example 12 was 45.3%, and the compression set rate of the composite composition using Comparative Example 4 which did not use the catalyst modifier of the present invention was 52%. Therefore, it was confirmed that when the EPDM copolymer produced by the production method of the present invention was used, the compression set rate of the composite composition was lower and it was used for automobile weather strips.

[0128] [Table 2]

[0129] EPDM Type Compression set rate (%) EPDM Color Experimental Example 1 Comparative Example 4 52.0 White Experimental Example 2 Example 12 45.3 White

[0130] As described above, the present invention is described through specific contents and limited embodiments, but this is only provided to help a more comprehensive understanding of the present invention. The present invention is not limited to the above embodiments, and technicians in the field of the present invention can make various modifications and variations based on these records.

[0131] Therefore, the concept of the present invention should not be limited to the illustrated embodiments, and all contents of the claims of the present invention and equivalents to the claims or equivalent modifications belong to the scope of the concept of the present invention.

Claims

1. A method for preparing EPDM copolymers, which is a solution polymerization method for preparing ethylene-propylene-diene (EPDM) copolymers using a Ziegler-Natta catalyst system, in, The Ziegler-Natta catalyst system comprises VOCl3, ethylaluminum sesquichloride (EASC) and a linear or branched C4-C6 alkylamine as a catalyst modifier, and includes a polymerization step of adding the catalyst modifier before injecting VOCl3 or adding VOCl3 and the catalyst modifier simultaneously to carry out polymerization.

2. The method for preparing EPDM copolymer according to claim 1, wherein: The EPDM copolymer has a molecular weight distribution Mw / Mn of 5 or less and a residual vanadium content of 20 ppm or less.

3. The method for preparing EPDM copolymer according to claim 2, wherein: The molecular weight distribution Mw / Mn is 2 to 3.

4. The method for preparing EPDM copolymer according to claim 1, wherein: The weight average molecular weight of the EPDM copolymer is 200,000-400,000 g / mol.

5. The method for preparing EPDM copolymer according to claim 1, wherein: The content of the catalyst modifier is 0.25 mol to 1 mol relative to 1 mol of VOCl3.

6. The method for preparing EPDM copolymer according to claim 1, wherein: The content of the catalyst modifier is 0.5 to 1 mole relative to 1 mole of VOCl3.

7. The method for preparing EPDM copolymer according to claim 1, wherein: The catalyst modifier is n-butylamine.

8. The method for preparing EPDM copolymer according to claim 1, wherein: The preparation method is prepared by a batch or continuous polymerization method.

9. The method for preparing EPDM copolymer according to claim 1, wherein: The solvent used in the solution polymerization reaction is a hydrocarbon-based solvent.

10. The method for preparing EPDM copolymer according to claim 9, wherein: The hydrocarbon-based solvent is any one selected from pentane, hexane, heptane and octane, or a mixture of two or more thereof.

11. The method for preparing an EPDM copolymer according to claim 1, wherein: The polymerization step is carried out at 30-50°C.

12. The method for preparing EPDM copolymer according to claim 1, wherein: In the polymerization step, the content ratio of propylene, ethylene and 5-ethylidene-2-norbornene (ENB) is propylene: 20-40 wt %, ethylene: 50-70 wt % and 5-ethylidene-2-norbornene (ENB): 5-10 wt %.

13. An EPDM copolymer, prepared by the preparation method according to any one of claims 1 to 12.

14. A composite composition comprising an EPDM copolymer, wherein the EPDM copolymer is prepared by the preparation method according to any one of claims 1 to 12.

15. The composite composition according to claim 14, wherein The composite composition has a compression set of 50% or less when the composite composition is maintained at 120° C. and compressed to 25% for 22 hours in accordance with ASTM D-395.

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