Ethylene / alpha-olefin copolymer and preparation method thereof

Abstract

Disclosed are an ethylene / alpha-olefin copolymer having an ethylene unit repeatability index (ERI) of 1.20 or less and a method for preparing the same.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to ethylene / α-olefin copolymers and methods for preparing the same. Background Art

[0002] Hot melt adhesives are adhesives obtained from resins such as blends of polyolefin elastomers, polypropylene-based polymers, and amorphous polyolefins. Hot melt adhesives are eco-friendly adhesives that achieve adhesive strength quickly compared to other adhesives and do not contain solvents. Therefore, hot melt adhesives are increasingly widely used in fields such as papermaking, woodworking, construction, packaging, sanitary products, and electronic devices.

[0003] Various studies have been conducted to improve the properties of polyolefins used in such hot melt adhesives. For example, Korean Patent Publication No. 10-2019-0013859 discloses a composition containing a propylene-based copolymer having a density of 0.850 g / cc to 0.900 g / cc, a vinyl polymer composition having a melt viscosity of 10 mPa·s to 1,000 mPa·s at 140°C, and a tackifier.

[0004] However, conventional amorphous polypropylene used in hot melt adhesives is not suitable for combination with various types of plasticizers, waxes, fillers, and tackifiers due to a lack of stereoregularity. Then, copolymers or terpolymers prepared using amorphous polyalphaolefins (APAO) and Ziegler-Natta catalysts with improved physical properties have been proposed (e.g., Vestoplast from Evonik, Rextac from REXtac, Eastoflex from Eastman Chemical, etc.). Recently, metallocene catalysts have been used to produce polyolefins with more complex and superior properties. In particular, catalyst systems that can produce ethylene- or propylene-based copolymers (e.g., Affinity, Engage, Versify from DOW Chemical, Vistamaxx from ExxonMobil, etc.) using 1-butene and 1-octane comonomers are being developed.

[0005] Recently, in paper or film production, there has been an increasing need for hot melt adhesives that exhibit a predetermined level of adhesive strength with a small amount of adhesive. Specifically, there is an urgent need to develop hot melt adhesives that exhibit excellent low-temperature tackiness and coatability and satisfactory adhesive strength over a wide temperature range.

[0006] [Prior Art Documents] [Patent Documents] 1. Korean Patent Publication No. 10-2019-0013859 Summary of the Invention Embodiments of the present disclosure provide an adhesive copolymer having excellent adhesive strength at room temperature and low temperature, and the adhesive copolymer uses an ethylene / α-olefin copolymer having a continuous sequence of a small amount of ethylene repeat units in its molecular structure. For an ethylene / α-olefin copolymer for achieving the above object according to an embodiment of the present disclosure, the ethylene unit repeatability index (ERI) is 1.20 or less, and the ERI is defined by the following Equation 1: [Equation 1]

[0007] where [EE] (ethylene-ethylene), [EO] (ethylene-α-olefin), and [OO] (α-olefin-α-olefin) are the diad fractions of the ethylene / α-olefin copolymer measured by 13 C-NMR; and C E / C O is the ratio of the number of moles of ethylene ( C E ) in the liquid phase to the number of moles of α-olefin ( C O ).

[0008] In one or more embodiments, the ratio of the number of moles of ethylene (C E ) to the number of moles of α-olefin (C O ) may be 6.0 to 11.0. In one or more embodiments, [EE] may be 0.75 to 0.85, [EO] may be 0.15 to 0.25, and [OO] may be 0.001 to 0.05.

[0009] In one or more embodiments, the α-olefin may include at least one selected from the group consisting of 1-butene, 1-hexene, 1-pentene, 4-methyl-1-pentene, and 1-octene. In one or more embodiments, the molecular weight distribution (Mw / Mn, PDI) of the ethylene / α-olefin copolymer may be 1.97 to 2.5.

[0010] In one or more embodiments, the number average molecular weight (Mn) of the ethylene / α-olefin copolymer can be from 10,000 g / mol to 25,000 g / mol and the weight average molecular weight (Mw) can be from 25,000 g / mol to 50,000 g / mol.

[0011] In one or more embodiments, the Brookfield viscosity of the ethylene / α-olefin copolymer at 190 °C can be from 4,000 cps to 15,000 cps. In one or more embodiments, the melting temperature (T m ) of the ethylene / α-olefin copolymer can be from 50 °C to 90 °C, the crystallization temperature (T c ) can be from 45 °C to 80 °C, and the glass transition temperature (T g ) can be from -70 °C to -40 °C. A method for preparing an ethylene / α-olefin copolymer for achieving the above object according to another embodiment of the present disclosure includes: polymerizing a supplied feed stream in the presence of a catalyst including at least one of a transition metal catalyst or a cocatalyst to produce a reaction product, and obtaining an ethylene / α-olefin copolymer from the reaction product, wherein the ERI (ethylene unit repeatability index) of the ethylene / α-olefin copolymer is 1.20 or less, and the ERI is defined by the following Equation 1: [Equation 1]

[0012] where [EE] (ethylene-ethylene), [EO] (ethylene-α-olefin), and [OO] (α-olefin-α-olefin) are the dyad fractions of the ethylene / α-olefin copolymer measured by 13 C-NMR; and C E / C O is the ratio of the number of moles of ethylene ( C E ) to the number of moles of α-olefin ( C O ) in the liquid phase.

[0013] In one or more embodiments, the feed stream can contain a monomer and a comonomer, the monomer can include ethylene, and the comonomer can include at least one selected from the group consisting of 1-butene, 1-hexene, 1-pentene, 4-methyl-1-pentene, and 1-octene. In one or more embodiments, in the polymerization reaction, the monomer may be supplied at a flow rate of 50 g / hr to 350 g / hr, the comonomer may be supplied at a flow rate of 50 g / hr to 250 g / hr, and the ratio of the flow rate of the monomer to the flow rate of the comonomer may be 0.1 to 2.

[0014] In one or more embodiments, in the polymerization reaction, hydrogen may be supplied at a flow rate of 0.01 g / hr to 0.3 g / hr.

[0015] In one or more embodiments, the polymerization reaction may be carried out at a temperature of 70 °C to 140 °C and a pressure of 30 bar to 100 bar. In one or more embodiments, the transition metal catalyst may include at least one selected from the group consisting of the catalyst represented by Formula 1 and the catalyst represented by Formula 2: [Formula 1]

[0016] [Formula 2]

[0017] Wherein M is titanium, zirconium or hafnium; B is an alkylene group having 1 to 20 carbon atoms, an arylene group having 6 to 20 carbon atoms, a dialkylsilyl group having 1 to 20 carbon atoms, a dialkylgermyl group having 1 to 20 carbon atoms, an alkylphosphine group having 1 to 20 carbon atoms or an alkylamine group having 1 to 20 carbon atoms; X1 and X2 are each independently a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkaryl group having 7 to 40 carbon atoms, an aralkyl group having 7 to 40 carbon atoms, an alkylamido group having 1 to 20 carbon atoms, an arylamido group having 6 to 20 carbon atoms, an alkylene group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms; and R1 to R7 are each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkaryl group having 7 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, a cycloalkyl group having 5 to 60 carbon atoms, a heterocyclic group having 4 to 20 carbon atoms, an alkynyl group having 1 to 20 carbon atoms, a heteroaryl group having 6 to 20 carbon atoms or a silyl group having 6 to 20 carbon atoms.

[0018] The cocatalyst may contain an activator compound and a co-activator compound. The activator compound includes a boron compound, and the co-activator compound includes an organoaluminum compound. The boron compound may include at least one selected from the group consisting of triphenylcarbenium tetrakis(pentafluorophenyl)borate, N,N-dimethylcyclohexylammonium tetrakis(pentafluorophenyl)borate, N,N-dimethylbenzylammonium tetrakis(pentafluorophenyl)borate, and N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate. The organoaluminum compound may include at least one selected from the group consisting of alkylaluminums, including dimethylaluminum, dimethylethylaluminum, trimethylaluminum, triethylaluminum, tributylaluminum, trihexylaluminum, trioctylaluminum, triisopropylaluminum, or triisobutylaluminum; alkylaluminum halides, including dimethylaluminum chloride, diethylaluminum chloride, methyldichloroaluminum, ethyldichloroaluminum, dimethylaluminum fluoride, or sesquiethylaluminum chloride; dialkylaluminum hydrides, including diethylaluminum hydride or diisobutylaluminum hydride, methylaluminoxane, and modified methylaluminoxane.

[0019] In the polymerization reaction, the transition metal catalyst may be supplied at 0.001 μmol / min to 0.040 μmol / min, and the cocatalyst may be supplied at 0.01 μmol / min to 0.2 μmol / min.

[0020] The ethylene / α-olefin copolymer for achieving the above object according to another embodiment of the present disclosure is prepared using the method described above.

[0021] The composition for hot melt adhesives for achieving the above object according to another embodiment of the present disclosure contains the ethylene / α-olefin copolymer described above. Detailed Description

[0022] The terms or words used in the specification and claims of the present disclosure should not be limited to the ordinary or dictionary meanings, but should be interpreted as meanings and concepts conforming to the technical concept of the present disclosure based on the principle that the inventor can appropriately define the terms to best explain his or her invention. As used herein, the term "stream" may mean the flow of a fluid in a process, and may also mean the fluid itself flowing in a pipe. Specifically, the term "stream" may mean both the fluid itself flowing in the pipe connecting each device and the flow of the fluid. Additionally, the fluid may mean a gas or a liquid, and does not exclude a fluid containing solid components.

[0023] Embodiments are provided to more fully illustrate the present disclosure to those of ordinary skill in the art. The following embodiments may be modified in various other forms, and the scope of the present disclosure is not limited to the following embodiments. <Ethylene / α-olefin Copolymer> The ethylene / α-olefin copolymer according to one embodiment satisfies an ERI (ethylene unit repeatability index) of 1.20 or less, and the ERI (ethylene unit repeatability index) is defined by the following Equation 1: [Equation 1]

[0024] where [EE] (ethylene-ethylene), [EO] (ethylene-α-olefin), and [OO] (α-olefin-α-olefin) are the number of dyad fractions of the ethylene / α-olefin copolymer measured by 13 C-NMR; and C E / C O is the ratio of the number of moles of ethylene in the liquid phase ( C E ) to the number of moles of α-olefin ( C O ).

[0025] The ethylene / α-olefin copolymer according to the present disclosure has a small number of ethylene repeat units in its molecular structure and may have an ERI (ethylene unit repeatability index) of 1.20 or less (e.g., 1.15 or less). When the ERI satisfies the range specified above, the ethylene / α-olefin copolymer can form a molecular structure as follows: where the distribution of ethylene repeat units and short-chain branches in the main chain is uniform. Even in small amounts, the ethylene / α-olefin copolymer can provide excellent adhesiveness in a wide temperature range from room temperature to low temperature.

[0026] [EE] can be from 0.75 to 0.85, [EO] can be from 0.15 to 0.25, and [OO] can be from 0.001 to 0.05. When [EE], [EO], and [OO] fall within the ranges specified above, even in small amounts, the ethylene / α-olefin copolymer can provide excellent adhesiveness in a wide temperature range from room temperature to low temperature.

[0027] The α-olefin may include at least one selected from the group consisting of 1-butene, 1-hexene, 1-pentene, 4-methyl-1-pentene, and 1-octene. The molecular weight distribution (Mw / Mn, PDI) of the ethylene / α-olefin copolymer may be from 1.97 to 2.5. When Mw / Mn is higher than the range specified above, the productivity of the target product may decrease.

[0028] The number-average molecular weight (Mn) of the ethylene / α-olefin copolymer can be from 10,000 g / mol to 25,000 g / mol and the weight-average molecular weight (Mw) can be from 25,000 g / mol to 50,000 g / mol. When the number-average molecular weight and the weight-average molecular weight are lower than the ranges specified above, the adhesive strength of the hot melt adhesive may deteriorate due to too low viscosity and cohesion. When the number-average molecular weight and the weight-average molecular weight are higher than the ranges specified above, it may be difficult to apply the hot melt adhesive due to too high viscosity of the hot melt adhesive. The Brookfield viscosity of the ethylene / α-olefin copolymer at 190 °C is from 4,000 cps to 15,000 cps. When the Brookfield viscosity is lower than the range specified above, the adhesive strength of the hot melt adhesive may deteriorate due to too low molecular weight and cohesion. When the Brookfield viscosity is higher than the range specified above, it may be difficult to apply the hot melt adhesive due to too high molecular weight of the hot melt adhesive. The melting temperature (T m ) of the ethylene / α-olefin copolymer can be from 50 °C to 90 °C, the crystallization temperature (T c ) can be from 45 °C to 80 °C, and the glass transition temperature (T g ) can be from -70 °C to -40 °C. When the melting temperature and the crystallization temperature are lower than the ranges specified above, the thermal stability may decrease. When the melting temperature and the crystallization temperature are higher than the ranges specified above, the viscosity of the adhesive composition containing the above copolymer may deviate from the target viscosity, or the mechanical properties and processability related thereto may deteriorate. When the glass transition temperature is lower than the range specified above, the heat resistance may decrease. When the glass transition temperature is higher than the range specified above, the tackiness of the hot melt adhesive may increase while the cold resistance may decrease.

[0029] <Method for preparing an ethylene / α-olefin copolymer> A method for preparing an ethylene / α-olefin copolymer according to one embodiment includes: polymerizing a supplied feed stream in the presence of a catalyst including at least one of a transition metal catalyst or a cocatalyst to produce a reaction product, and obtaining an ethylene / α-olefin copolymer from the reaction product. The ethylene / α-olefin copolymer prepared by the method satisfies an ERI (ethylene unit repeatability index) of 1.20 or less, and the ERI (ethylene unit repeatability index) is defined by the following Equation 1: [Equation 1]

[0030] where [EE] (ethylene-ethylene), [EO] (ethylene-α-olefin), and [OO] (α-olefin-α-olefin) are determined by 13The dyad fraction of the ethylene / α-olefin copolymer measured by 13C-NMR; and C E / C O is the ratio of the number of moles of ethylene in the liquid phase ( C E ) to the number of moles of α-olefin ( C O ).

[0031] Feed stream The feed stream includes a monomer and a comonomer, wherein the monomer includes ethylene, and the comonomer includes an α-olefin monomer having 2 to 20 carbon atoms, such as an aliphatic α-olefin monomer having 6 to 20 carbon atoms. The comonomer may be a linear α-olefin, such as propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-dodecene or 1-tetradecene; or a branched α-olefin, such as 3-methyl-1-pentene or 4-methyl-1-pentene; or a mixture thereof, and may be used alone or in combination or in the form of its isomers. For example, the comonomer may include at least one selected from the group consisting of 1-butene, 1-hexene, 1-pentene, 4-methyl-1-pentene and 1-octene.

[0032] In the polymerization reaction, the monomer is supplied at 50 g / hr to 350 g / hr, the comonomer is supplied at 50 g / hr to 250 g / hr, and the ratio of the monomer flow rate to the comonomer flow rate may be 0.1 to 2. When the supply rates of the monomer and the comonomer are lower than the ranges specified above, the amount of the catalyst fed may be relatively large, which may cause deterioration in quality, such as color change due to excessive catalyst, or the amount of the polymerization product may be too small, which may cause a decrease in productivity. When the ratio of the flow rate of the monomer to the flow rate of the comonomer does not fall within the ranges specified above, the molecular weight and viscosity of the product may deviate from the target molecular weight and viscosity.

[0033] In the polymerization reaction, hydrogen may be supplied at 0.01 g / hr to 0.3 g / hr. When the hydrogen supply rate exceeds the above range, a chain transfer reaction proceeds in the direction of reducing the molecular weight of the ethylene / α-olefin copolymer, rather than a chain growth reaction in the direction of increasing the molecular weight of the ethylene / α-olefin copolymer, and thus the molecular weight and viscosity of the product may deviate from the target molecular weight and viscosity. In the polymerization reaction, the polymerization temperature and pressure can vary depending on the reactants, reaction conditions, etc., but can generally be carried out at a temperature of 70 °C to 140 °C and a pressure of 30 bar to 100 bar in the presence of an inert gas such as argon or nitrogen. When the temperature is below the range specified above, the chain growth reaction proceeds better than the chain transfer reaction that proceeds in the direction of decreasing the molecular weight of the ethylene / α-olefin copolymer. For this reason, high molecular weight and high viscosity copolymers are formed, and thus the molecular weight and viscosity of the product may deviate from the target molecular weight and viscosity. When the temperature exceeds the range specified above, the thermal stability of the catalyst may deteriorate, and thus the catalyst activity may deteriorate. When the pressure is below the range specified above, the solubility of the monomer in the solvent may decrease, which may reduce the polymerization activity, or during the hydrogen reaction, the fluctuations may become severe and the reaction may not be able to stabilize. When the pressure exceeds the range specified above, a large amount of energy may be used during operation, but without any specific benefit, which may reduce the operation efficiency.

[0034] The polymerization reaction can be carried out as a liquid-phase polymerization, slurry-phase polymerization, bulk polymerization or gas-phase polymerization in a hydrocarbon solvent. The hydrocarbon solvent can be an aliphatic hydrocarbon solvent having 5 to 20 carbon atoms, such as: aliphatic hydrocarbon solvents such as pentane, hexane, heptane, nonane, decane or their isomers, aromatic hydrocarbon solvents such as toluene, benzene or xylene, halogen atom-containing hydrocarbon solvents such as chlorobenzene, or a combination thereof. The polymerization reaction can be carried out as a batch, semi-continuous or continuous reaction in a single reactor (such as a batch reactor) or a loop reactor or a combination thereof.

[0035] Catalyst The catalyst contains at least one of a transition metal catalyst or a cocatalyst.

[0036] Transition metal catalyst The transition metal catalyst is an organometallic compound including two ligands connected to each other via a bridging group. The transition metal catalyst can include at least one selected from the group consisting of the catalyst represented by Formula 1 and the catalyst represented by Formula 2: [Formula 1]

[0037] [Formula 2]

[0038] Wherein M is titanium, zirconium or hafnium; B is an alkylene group having 1 to 20 carbon atoms, an arylene group having 6 to 20 carbon atoms, a dialkylsilyl group having 1 to 20 carbon atoms, a dialkylgermyl group having 1 to 20 carbon atoms, an alkylphosphine group having 1 to 20 carbon atoms or an alkylamine group having 1 to 20 carbon atoms; X1 and X2 are each independently a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkaryl group having 7 to 40 carbon atoms, an aralkyl group having 7 to 40 carbon atoms, an alkylamido group having 1 to 20 carbon atoms, an arylamido group having 6 to 20 carbon atoms, an alkylene group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms; and R1 to R7 are each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkaryl group having 7 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, a cycloalkyl group having 5 to 60 carbon atoms, a heterocyclic group having 4 to 20 carbon atoms, an alkynyl group having 1 to 20 carbon atoms, a heteroaryl group having 6 to 20 carbon atoms or a silyl group having 6 to 20 carbon atoms.

[0039] Cocatalyst The cocatalyst may contain an activator compound, a co-activator compound or a mixture thereof.

[0040] The activator compound reacts with the transition metal catalyst to form an ionic compound and may include a boron compound. The boron compound may include at least one selected from the group consisting of triphenylcarbenium tetrakis(pentafluorophenyl)borate, N,N-dimethylcyclohexylammonium tetrakis(pentafluorophenyl)borate, N,N-dimethylbenzylammonium tetrakis(pentafluorophenyl)borate and N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate.

[0041] The mixing ratio (molar ratio) of the transition metal catalyst to the activator compound may fall within the range of 10:1 to 1:100, for example 2:1 to 1:10. When the mixing ratio of the activator compound to the transition metal catalyst is less than the range specified above, the activation of the transition metal catalyst may not be fully achieved, making it difficult to control the polymerization reaction, while when the mixing ratio is greater than the range specified above, non-activated compounds may cause side reactions, making it difficult to control the polymerization reaction. The co-activator compound functions to promote the activation of the catalyst and may include an organoaluminum compound. The organoaluminum compound may be selected from the group consisting of: alkylaluminum such as dimethylaluminum, dimethylethylaluminum, trimethylaluminum, triethylaluminum, tributylaluminum, trihexylaluminum, trioctylaluminum, triisopropylaluminum or triisobutylaluminum; alkylaluminum halide such as dimethylaluminum chloride, diethylaluminum chloride, methyldialuminum chloride, ethyldialuminum chloride, dimethylaluminum fluoride or sesquiethylaluminum chloride; dialkylaluminum hydride such as diethylaluminum hydride or diisobutylaluminum hydride, methylaluminoxane and modified methylaluminoxane.

[0042] The mixing ratio (molar ratio) of the transition metal catalyst to the co-activator compound may fall within the range of 1:1 to 1:10,000, for example 1:5 to 1:1,000. When the mixing ratio of the co-activator compound to the transition metal catalyst is less than the range specified above, the amount of the co-activator compound may be small, and thus the alkylation of the catalyst compound may not proceed completely. When the mixing ratio exceeds the range specified above, activation may not be fully achieved due to side reactions between the compounds. The α-olefin monomer used herein is sensitive to moisture. Therefore, it is important to control the moisture contained therein due to catalyst poisoning, etc., and it is preferable to use the co-activator compound as a scavenger to reduce the influence of moisture on the polymerization reaction. The use ratio (molar ratio) of the co-activator compound to moisture falls within the range of 1:1 to 1:1,000, for example 1:1 to 1:100. When the ratio of the co-activator compound to moisture is less than the range specified above, the scavenger may not function properly, which may lead to a decrease in the polymerization activity of the catalyst activated by moisture. When the ratio exceeds the range specified above, the total amount may be greater than the amount required for scavenging or alkylating the catalyst compound, which may lead to side reactions or inhibition of the polymerization reaction.

[0043] The amount of the catalyst used may be 0.001 mol% to 1 mol%, for example 0.001 mol% to 0.1 mol% relative to the feed stream used to form the ethylene / α-olefin copolymer. When the content of the catalyst is less than the range specified above, the polymerization reaction may not proceed sufficiently. When the content exceeds the range specified above, quality deterioration may occur, such as discoloration due to an excess of the catalyst, difficulty in post-treatment, difficulty in controlling the polymerization reaction and reactor failure.

[0044] In the polymerization reaction, the transition metal catalyst may be supplied at 0.001 μmol / min to 0.040 μmol / min, and the cocatalyst may be supplied at 0.01 μmol / min to 0.2 μmol / min. When the supply rate of the transition metal catalyst is less than the range specified above, the amount of the catalyst fed may be too small compared to the amount of the monomer fed, and thus the polymerization reaction may not proceed properly, and products having a molecular weight higher than the target and a higher molecular weight may be produced. When the supply rate of the cocatalyst is less than the range specified above, the activation of the transition metal catalyst may not be fully carried out, making it difficult to control the polymerization reaction, while when the supply rate of the cocatalyst exceeds the range specified above, side reactions may be caused by the non-activated compound, making it difficult to control the polymerization reaction.

[0045] Specific embodiments of the present disclosure will be described below. However, the embodiments described below are provided only to illustrate or explain the present disclosure in detail and should not be construed as limiting the scope of the present disclosure. In addition, other details that can be fully conceived by those skilled in the art technically will not be described. [Synthesis Example 1: Synthesis of Transition Metal Catalyst A] The transition metal catalyst A of Formula 1 ([di-phenyl-silanediyl-bis(2-methyl-4-phenylindenyl)]-zirconium dimethyl) was synthesized according to the methods described in Organometallics 1994, 13, 954-963 and J. Mol. Catal. A: chem. 1998, 130, 149-162. Unless the ratio of the racemic isomer to the meso isomer is indicated, the crosslinked metallocene compound refers to the crosslinked metallocene compound obtained only as a racemic compound. [Synthesis Example 2: Synthesis of Transition Metal Catalyst B] The transition metal catalyst B of Formula 2 (1-(n-butylcyclopentadienyl)-1-(2,7-di-tert-butylfluorenyl)-1,1-diphenylmethylidene zirconium dimethyl) was synthesized according to the methods described in KR 10-1437509 and J. Mol. Catal. A: chem. 1998, 130, 149-162. Unless the ratio of the racemic isomer to the meso isomer is indicated, the crosslinked metallocene compound refers to the crosslinked metallocene compound obtained only as a racemic compound.

[0046] [Preparation Example: Preparation of Ethylene / α-Olefin Copolymer] Preparation Example 1 1 L of hexane was charged into a 1 L stainless-steel autoglaze continuous process reactor, and the internal temperature of the reactor was maintained at a polymerization temperature of 90 °C. When injecting 2000 g / hr of hexane, 120 g / hr of 1-octene, and 0.17 g / hr of hydrogen through LMFC and MFC, 0.0034 μmol / min of transition metal catalyst A, 0.014 μmol / min of cocatalyst 1 (dimethylanilinium tetrakis(pentafluorophenyl)borate), and 0.04 mmol / min of cocatalyst 2 (triisobutylaluminum) were simultaneously charged into the reactor to initiate the polymerization reaction. Subsequently, the polymerization reaction was carried out under the conditions of 120 g / hr of ethylene and 0.017 g / hr of hydrogen, while maintaining a polymerization reaction pressure of 50 bar and a polymerization temperature of 90 °C. The polymerization was terminated with Irganox 1076, hexane, and isopropanol, and the residual solvents and raw materials were removed in a vacuum oven at 150 °C for 6 hours or longer to prepare the ethylene / α-olefin copolymer of Preparation Example 1.

[0047] Preparation Examples 2 to 14 Except for using the conditions in Table 1, the ethylene / α-olefin copolymers of the corresponding preparation examples were prepared in the same manner as Preparation Example 1.

[0048] [Table 1]

[0049] [Measurement of Physical Properties] The physical properties of the ethylene / α-olefin copolymers of the corresponding preparation examples and the ethylene / α-olefin copolymers of the corresponding comparative examples were measured according to the following methods, and the results are shown in Tables 2 and 3 below. The ethylene / α-olefin copolymer of Comparative Example 1 is Affinity 1900 from DOW Corporation, and the ethylene / α-olefin copolymer of Comparative Example 2 is Affinity 1950 from DOW Corporation.

[0050] Number-average molecular weight and weight-average molecular weight According to the following method, a gel permeation chromatography-RI (GPC-RI; Polymer Laboratory Inc. 220 System) equipped with a refractive index detector (RI detector) was used to measure the number average molecular weight and the weight average molecular weight. Two Olexis and one Guard were used as separation columns, and the column temperature was maintained at 160 °C. Calibration was performed using a standard polystyrene set from Polymer Laboratory Inc. Trichlorobenzene containing 0.0125 wt% antioxidant (BHT) was used as the eluent, the sample concentration was 1.0 mg / mL, and the measurement was performed at a pump flow rate of 1.0 mL / min with a feed volume of 0.2 mL for 27 minutes. Universal calibration was performed using Easical A and Easical B (Agilent) as polystyrene standard materials, the conversion to polyethylene was performed, and the number average molecular weight (Mn) and the weight average molecular weight (Mw) were calculated.

[0051] Viscosity The following measurement was performed using a Brookfield viscometer (BROOKFIELD DV2T viscometer). 10 g of the ethylene / α-olefin copolymer of each of the preparation examples and the comparative examples was heated to 190 °C using a Thermo-cell and allowed to stand until the sample was completely melted, and then the viscometer was lowered and the spindle (No. 27) was fixed. The rotation speed of the spindle (No. 27) was fixed at 0.5 rpm and monitored until the value was stable, and then the final value was recorded.

[0052] Crystallization temperature (T c ), melting temperature (T m ), and glass transition temperature (T g ） The following measurements were carried out using a differential scanning calorimeter (DSC, TA's Q2000). The temperature of the ethylene / α-olefin copolymer in each of the Preparation Examples and Comparative Examples was cooled to -80 °C and maintained for 1 minute. The ethylene / α-olefin copolymer was reheated to 200 °C at 40 °C / min and maintained for 2 minutes. The ethylene / α-olefin copolymer was cooled to -80 °C at 5 °C / min and maintained for 2 minutes. Finally, the ethylene / α-olefin copolymer was heated to 200 °C at 10 °C / min. The values measured in each section were defined as the crystallization temperature, melting temperature, and glass transition temperature.

[0053] Sequence The following measurements were carried out using an Avance III 500 MHz (Bruker Biospin nuclear magnetic resonance apparatus). Tetrachloroethane (tetrachloroethane-d4, Acros, 99.8 atom % D) as a solvent and 10 wt% of the ethylene / α-olefin copolymer in each of the Preparation Examples and Comparative Examples were charged into a sample tube, and a 13 13C-NMR spectrum was obtained using the nuclear magnetic resonance apparatus under the conditions of a 45 μs pulse width, a 10 s pulse repetition time, and a temperature of 110 °C to measure the contents of ethylene and α-olefin in the copolymer. The triad fractions [EEE], [EEO+OEE], [EOE], [EOO+OOE], [OEO], and [OOO], the dyad fractions [EE], [EO], and [OO], the number of moles of ethylene ( C E ), and the number of moles of α-olefin ( C O ), were determined from the obtained 13 13C-NMR spectrum according to the equations disclosed in J. Macromol. Sci. Part C: Polym. Rev. 1989, 29, 201-317, J. Polym. Sci. Part A: Polym. Chem. 1994, 32, 2979-2987, and RSC Adv. 2017, 7, 10175-10182.

[0054] Kraft paper and BOPP adhesive strength Melt the ethylene / α-olefin copolymer of each of the preparation examples and comparative examples at 180 °C for 3 minutes, prepare two kraft paper films (width 14.8 cm, length 10.5 cm), and apply five liners with a thickness of 3.0 mm and a length of 2.0 cm to one surface. Cover the other surface and press under a pressure of 2.8 kgf / cm using a thermal gradient tester (Toyoseiki) for an average of 5 seconds or until melted. Cut the liner into pieces with a thickness of 1.0 cm and age for 24 hours under constant temperature and humidity conditions, and measure the kraft paper adhesion strength using a multi-axis precision adhesiveness testing device (YEONJIN S-Tech, TXA) under the conditions of a width of 10.0 mm, a speed of 0.8334 mm / s, a test time of 70 s, and a temperature (room temperature, -20 °C).

[0055] Measure the BOPP adhesion strength in the same manner as the measurement of the kraft paper adhesion strength, except that a BOPP (biaxially oriented polypropylene) film (width 15.0 cm, length 11.0 cm) is used.

[0056] [Table 2]

[0057] [Table 3]

[0058] As can be seen from the above Tables 2 and 3, the ethylene / α-olefin copolymers of Preparation Examples 1 to Preparation Example 14 having an ERI according to the present disclosure exhibit excellent adhesion strength at room temperature and low temperature. On the other hand, as a result of the preparation physical properties among ethylene / α-olefin copolymers within a similar viscosity range, compared with the ethylene / α-olefin copolymers of Preparation Examples 1 to Preparation Example 5 according to the present disclosure, the ethylene / α-olefin copolymer of Comparative Example 1 not falling within the ERI range according to the present disclosure exhibits poor adhesion strength. Also, compared with the ethylene / α-olefin copolymers of each of Preparation Examples 6 to Preparation Example 14 according to the present disclosure, the ethylene / α-olefin copolymer of Comparative Example 2 not falling within the ERI range according to the present disclosure exhibits poor adhesion strength.

[0059] As is apparent from the foregoing description, the present disclosure provides a copolymer for adhesives, which exhibits excellent adhesive strength at room temperature and low temperature, using an ethylene / α-olefin copolymer having a continuous sequence of a small amount of ethylene repeat units in its molecular structure. The ethylene / α-olefin copolymer according to the present disclosure has a small amount of ethylene repeat units in its molecular structure, and thus the ethylene repeat units and short-chain branches are uniformly distributed in the main chain. The ethylene / α-olefin copolymer of the present disclosure is suitable for hot-melt adhesives, and even when applied in a small amount, the hot-melt adhesive has excellent adhesive strength over a wide temperature range.

Claims

1. An ethylene / α-olefin copolymer having an ethylene unit repetitiveness index (ERI) of 1.20 or less, wherein the ERI is defined by the following equation 1: [Equation 1] in [EE] (ethylene-ethylene), [EO] (ethylene-α-olefin) and [OO] (α-olefin-α-olefin) are obtained by 13 C-NMR measurement of the diad fraction of the ethylene / α-olefin copolymer; and C E / C O is the number of moles of ethylene in the liquid phase ( C E ) and the number of moles of α-olefins ( C O ) ratio.

2. The ethylene / α-olefin copolymer according to claim 1, wherein the number of moles of ethylene ( C E ) and the number of moles of α-olefins ( C O ) ratio is 6.0 to 11.

0.

3. The ethylene / α-olefin copolymer according to claim 1, wherein [EE] is 0.75 to 0.85, [EO] is 0.15 to 0.25, and [OO] is 0.001 to 0.

05. 4 . The ethylene / α-olefin copolymer according to claim 1 , wherein the α-olefin comprises at least one selected from the group consisting of 1-butene, 1-hexene, 1-pentene, 4-methyl-1-pentene, and 1-octene. 5 . The ethylene / α-olefin copolymer according to claim 1 , wherein the molecular weight distribution (Mw / Mn, PDI) of the ethylene / α-olefin copolymer is 1.97 to 2.

5. The ethylene / α-olefin copolymer according to claim 1 , wherein the ethylene / α-olefin copolymer has a number average molecular weight (Mn) of 10,000 to 25,000 g / mol and a weight average molecular weight (Mw) of 25,000 to 50,000 g / mol. 7 . The ethylene / α-olefin copolymer according to claim 1 , wherein the ethylene / α-olefin copolymer has a Brookfield viscosity at 190° C. of 4,000 cps to 15,000 cps.

8. The ethylene / α-olefin copolymer according to claim 1, wherein the ethylene / α-olefin copolymer has a melting temperature (Tm) of 50 to 90°C, a crystallization temperature (Tc) of 45 to 80°C, and a glass transition temperature (Tg) of -70 to -40°C.

9. A method for preparing an ethylene / α-olefin copolymer, the method comprising: polymerizing the supplied feed stream in the presence of a catalyst comprising at least one of a transition metal catalyst or a co-catalyst to produce a reaction product; and An ethylene / α-olefin copolymer is obtained from the reaction product, wherein the ERI (ethylene unit repeatability index) of the ethylene / α-olefin copolymer is 1.20 or less, and the ERI is defined by the following equation 1: [Equation 1] in [EE] (ethylene-ethylene), [EO] (ethylene-α-olefin) and [OO] (α-olefin-α-olefin) are obtained by 13 C-NMR measurement of the diad fraction of the ethylene / α-olefin copolymer; and C E / C O is the number of moles of ethylene in the liquid phase ( C E ) and the number of moles of α-olefins ( C O ) ratio.

10. The process of claim 9, wherein the feed stream comprises monomers and comonomers, The monomer comprises ethylene, and The comonomer includes at least one selected from the group consisting of 1-butene, 1-hexene, 1-pentene, 4-methyl-1-pentene, and 1-octene.

11. The method according to claim 10, wherein: In the polymerization reaction, supplying the monomer at a flow rate of 50 g / hr to 350 g / hr, supplying the comonomer at a flow rate of 50 g / hr to 250 g / hr, and The ratio of the flow rate of the monomer to the flow rate of the comonomer is 0.1 to 2. 12 . The method according to claim 9 , wherein in the polymerization reaction, hydrogen is supplied at a flow rate of 0.01 g / hr to 0.3 g / hr.

13. The method of claim 9, wherein the polymerization reaction is performed at a temperature of 70 to 140°C and a pressure of 30 to 100 bar.

14. The method according to claim 9, wherein the transition metal catalyst comprises at least one selected from the group consisting of a catalyst represented by the following Formula 1 and a catalyst represented by the following Formula 2: [Formula 1] [Formula 2] in M is titanium, zirconium or hafnium; B is an alkylene group having 1 to 20 carbon atoms, an arylene group having 6 to 20 carbon atoms, a dialkylsilicon group having 1 to 20 carbon atoms, a dialkylgermanium group having 1 to 20 carbon atoms, an alkylphosphine group having 1 to 20 carbon atoms, or an alkylamine group having 1 to 20 carbon atoms; X1 and X2 are each independently a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkaryl group having 7 to 40 carbon atoms, an aralkyl group having 7 to 40 carbon atoms, an alkylamide group having 1 to 20 carbon atoms, an arylamide group having 6 to 20 carbon atoms, an alkylene group having 1 to 20 carbon atoms, or an alkoxy group having 1 to 20 carbon atoms; and R1 to R7 are each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkaryl group having 7 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, a cycloalkyl group having 5 to 60 carbon atoms, a heterocyclic group having 4 to 20 carbon atoms, an alkynyl group having 1 to 20 carbon atoms, a heteroaryl group having 6 to 20 carbon atoms, or a silyl group having 6 to 20 carbon atoms.

15. The method of claim 9, wherein the co-catalyst comprises an activator compound and a co-activator compound, the activator compound comprising a boron compound, and the co-activator compound comprising an organoaluminum compound.

16. The method according to claim 15, wherein the boron compound comprises at least one selected from the group consisting of triphenylcarbonium tetrakis(pentafluorophenyl)borate, N,N-dimethylcyclohexylammonium tetrakis(pentafluorophenyl)borate, N,N-dimethylbenzylammonium tetrakis(pentafluorophenyl)borate, and N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, and The organoaluminum compound comprises at least one selected from the group consisting of: alkylaluminum, including dimethylaluminum, dimethylethylaluminum, trimethylaluminum, triethylaluminum, tributylaluminum, trihexylaluminum, trioctylaluminum, triisopropylaluminum or triisobutylaluminum; alkylaluminum halide, including dimethylaluminum chloride, diethylaluminum chloride, methylaluminum dichloride, ethylaluminum dichloride, dimethylaluminum fluoride or sesquiethylaluminum chloride; dialkylaluminum hydride, including diethylaluminum hydride or diisobutylaluminum hydride, methylaluminumoxane and modified methylaluminumoxane.

17. The method according to claim 9, wherein: In the polymerization reaction, the transition metal catalyst is supplied at 0.001 μmol / min to 0.040 μmol / min, and the co-catalyst is supplied at 0.01 μmol / min to 0.2 μmol / min.

18. An ethylene / α-olefin copolymer prepared using the method according to any one of claims 9 to 17.

19. A composition for a hot melt adhesive, comprising the ethylene / α-olefin copolymer according to any one of claims 1 to 8.

20. A composition for a hot melt adhesive, comprising the ethylene / α-olefin copolymer according to claim 18.

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