WO2021071154A1 - Polyethylene and preparation method therefor - Google Patents

Abstract

The present invention provides: polyethylene exhibiting an improved low temperature sealing property through an increase in the amount and molecular weight of a low crystalline polymer; and a preparation method therefor.

Description

Polyethylene and its manufacturing method

Cross-reference with related application(s)

This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0126480 filed on October 11, 2019 and Korean Patent Application No. 10-2020-0125237 on September 25, 2020. All contents disclosed in the literature are included as part of this specification.

The present invention relates to polyethylene showing improved low-temperature sealing properties with an increase in the content and molecular weight of a low crystalline polymer and a method for producing the same.

Olefin polymerization catalyst systems can be classified into Ziegler-Natta and metallocene catalyst systems, and these two highly active catalyst systems have been developed according to their respective characteristics. Ziegler Natta catalysts have been widely applied to existing commercial processes since their invention in the 50s, but since they are multi-site catalysts with multiple active points, they are characterized by a wide molecular weight distribution of polymers. There is a problem in that there is a limit to securing desired physical properties because the composition distribution of is not uniform.

On the other hand, the metallocene catalyst is composed of a combination of a main catalyst composed of a transition metal compound and a cocatalyst composed of an organometallic compound composed mainly of aluminum. Such a catalyst is a homogeneous complex catalyst and is a single site catalyst. And a polymer having a narrow molecular weight distribution and a uniform composition distribution of a comonomer is obtained according to the single active point characteristics.According to the modification of the ligand structure of the catalyst and the change of polymerization conditions, the stereoregularity of the polymer, copolymerization characteristics, molecular weight, It has properties that can change crystallinity and the like.

U.S. Patent No. 5,914,289 describes a method of controlling the molecular weight and molecular weight distribution of a polymer using a metallocene catalyst supported on each carrier, but it takes a lot of time and the amount of solvent used to prepare the supported catalyst. In addition, there was a hassle to support each of the metallocene catalysts used on the carrier.

Korean Patent Laid-Open Publication No. 2004-0076965 discloses a method of controlling the molecular weight distribution by polymerizing while changing the combination of catalysts in the reactor by supporting a double-nuclear metallocene catalyst and a single-nuclear metallocene catalyst on a carrier together with an activator. have. However, this method has a limitation in realizing the characteristics of each catalyst at the same time, and also has a disadvantage in that the metallocene catalyst portion is released from the carrier component of the completed catalyst, causing fouling in the reactor.

On the other hand, linear low-density polyethylene is prepared by copolymerizing ethylene and α-olefin at low pressure using a metallocene-based polymerization catalyst, has a narrow molecular weight distribution, has a short chain branch (SCB) of a constant length, and does not have a long chain branch (LCB). Linear low-density polyethylene film has excellent mechanical properties such as breaking strength, elongation, tear strength, and drop impact strength, as well as the properties of general polyethylene, so it is difficult to apply the existing low-density polyethylene or high-density polyethylene. The use is increasing.

In the case of a high-speed packaging film, it is required to increase the hot-tack strength in order to increase productivity. However, in the case of the conventional linear low-density polyethylene, there is a disadvantage of low low-temperature sealing strength due to high melting temperature (Tm). Accordingly, there is a problem in that the sealing property is poor during high-speed processing production, and the packaging material flows out.

[Prior technical literature]

[Patent Literature]

(Patent Document 1) U.S. Patent No. 5,914,289

(Patent Document 2) Korean Patent Publication No. 2004-0076965

Accordingly, the present invention is to solve the problems of the prior art, and to provide a polyethylene showing improved low-temperature sealing properties and a method of manufacturing the same by increasing the content and molecular weight of a low crystalline polymer.

In addition, the present invention exhibits excellent hot-tack strength properties, including the polyethylene, and as a result is intended to provide a film useful for high-speed packaging.

In order to solve the above problem, according to an embodiment of the present invention,

It includes an ethylene repeating unit and an α-olefin repeating unit,

The density measured according to ASTM D1505 is 0.916 g/cm ³ or more,

When analyzed by Temperature Rising Elution Fractionation (TREF), three elution temperatures of Te1, Te2 and Te3 corresponding to the elution temperatures of the first to third semicrystalline polymers in the temperature range of 20 to 120°C, respectively, were determined. And the temperature of Te2 is lower than that of Te3 and higher than that of Te1,

The Te1 is 25 to 30 ℃,

The first semi-crystalline polymer has a weight average molecular weight (Mw) of 200,000 g/mol or more, and is included in an amount of 5% by weight or more based on the total weight of polyethylene, providing polyethylene.

In addition, according to another embodiment of the present invention, hydrogen gas is introduced into the reactor in the presence of a catalyst composition including a first transition metal compound represented by the following formula (1) and a second transition metal compound represented by the following formula (2). And polymerizing an ethylene monomer and an α-olefin-based monomer having 3 or more carbon atoms, wherein the hydrogen gas is 10 ppm or more and 200 ppm based on the total weight of the monomer including an ethylene monomer and an α-olefin-based monomer having 3 or more carbon atoms. The method for producing polyethylene described above is introduced in an amount less than and wherein the molar ratio of the α-olefin monomer to the ethylene monomer present in the reactor (molar ratio of α-olefin monomer/ethylene monomer) is 0.25 or more during the polymerization reaction. to provide:

[Formula 1]

In Formula 1,

R ₁ and R ₂ are each independently hydrogen, halogen, C _1-20 alkyl, C _2-20 alkenyl, C _1-20 alkoxy, C _2-20 alkoxyalkyl, C _6-20 aryl, C _7-20 alkyl Aryl, or C _7-20 arylalkyl,

X ₁ and X ₂ are each independently halogen or C _1-20 alkyl,

[Formula 2]

In Chemical Formula 2,

R ₃ and R ₄ are each independently hydrogen, halogen, C _1-20 alkyl, C _2-20 alkenyl, C _1-20 alkoxy, C _2-20 alkoxyalkyl, C _6-20 aryl, C _7-20 alkyl Aryl, or C _7-20 arylalkyl,

X ₃ and X ₄ are each independently halogen or C _1-20 alkyl.

According to another embodiment of the present invention, a film including the above-described polyethylene, particularly, a film for high-speed packaging is provided.

The polyethylene according to the present invention can exhibit improved low-temperature sealing properties by increasing the polymer content and molecular weight of low crystallinity. Accordingly, when applied to the production of a packaging film, particularly a high-speed packaging film, it exhibits excellent hot-tack properties, thereby increasing productivity.

1 to 4 are graphs showing analysis results according to TREF (Temperature Rising Elution Fractionation) for polyethylene prepared in Example 1 and Comparative Examples 5 to 7, respectively.

5 to 7 are graphs showing the results of GPC (Gel Permeation Chromatography) analysis of the first semicrystalline polymer in the polyethylene prepared in Example 1 and Comparative Examples 5 and 6, respectively.

8 to 11 show SCB content according to polyethylene molecular weight obtained as a result of GPC-FTIR (Gel Permeation Chromatography-Fourier-transform infrared spectroscopy) analysis of polyethylenes prepared in Example 1 and Comparative Examples 5 to 7, respectively. It is a graph showing.

12 is a graph showing the results of measuring the low temperature sealing strength of the polyethylene prepared in Example 1 and Comparative Examples 5 to 7.

The terms used in the present specification are only used to describe exemplary embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present specification, terms such as "comprises", "includes" or "have" are intended to designate the existence of a feature, step, component, or combination of the implemented features, one or more other features or steps, It is to be understood that the possibility of the presence or addition of components, or combinations thereof, is not preliminarily excluded.

The present invention will be described in detail below and exemplify specific embodiments, as various changes may be made and may have various forms. However, this is not intended to limit the present invention to a specific form disclosed, it should be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention.

In the present invention, the term "short chain branching (SCB)" in polyethylene refers to a chain branched in the form of a branch with respect to the longest main chain in each of the polymer chains, specifically the number of carbon atoms. It means a chain of 2 to 7. The number of such short-chain branches can be calculated by FT-IR analysis of the polymer, and can be proportional to the content of the α-olefin-based monomer contained in the polymer chains.

Hereinafter, the polyethylene of the present invention, a method for producing the same, and a film using the same will be described in detail.

Specifically, polyethylene according to an embodiment of the present invention is an ethylene/α-olefin-based copolymer comprising an ethylene repeating unit and an α-olefin-based repeating unit,

The density measured according to ASTM D1505 is 0.916 g/cm ³ or more,

When analyzed by temperature rising elution fractionation (TREF), it represents the three elution temperatures of Te1, Te2 and Te3 respectively corresponding to the elution temperatures of the first to third semicrystalline polymers in a temperature range of 20 to 120°C, and Te2 is The temperature is lower than Te3 and higher than Te1,

The Te1 is 25 to 30 ℃,

The first semi-crystalline polymer has a weight average molecular weight (Mw) of 200,000 g/mol or more, and is included in an amount of 5% by weight or more based on the total weight of polyethylene.

The present inventors used a specific catalyst composition to be described later in the production of polyethylene, and as a result of controlling the mixing ratio of the ethylene monomer and the comonomer and the amount of hydrogen input, the produced polyethylene has a controlled density of a certain level or more, and is different from the conventional one. The present invention was completed by confirming that it exhibits crystal properties.

The crystal properties of the polyethylene were confirmed through TREF analysis. According to the analysis results, the polyethylene is distinguished from showing only one peak in the first to the same analysis result in three different specific temperature ranges.

More specifically, the first to third peaks are the fraction of polymer chains exhibiting different crystallinity in the polyethylene of one embodiment, more specifically, the first fraction showing the lowest crystallinity, and the third peak showing the highest crystallinity. It means that a fraction, and a second fraction exhibiting crystallinity between the first and third fractions, are included. As the first to third fractions of polymer chains having different crystallinity are simultaneously included in this way, polyethylene according to one embodiment has all physical properties required for various uses, for example, compatibility with other resins, and processability. , It is possible to simultaneously improve the strength and impact strength when alone or when compounded with other resins. This is presumed to be because the polyethylene contains polymer chains exhibiting various crystallinity at the same time.

In particular, it was confirmed that the polyethylene according to an embodiment of the present invention contains a first fraction showing low crystallinity at a high fractional ratio (fraction), and polymer chains included in this first fraction have a high molecular weight. As a result, polyethylene according to an embodiment of the present invention can not only excellently express various physical properties at the same time, but also can significantly improve sealing strength characteristics at low temperatures. Accordingly, it can be particularly useful in the manufacture of a high-speed packaging film that requires excellent hot-tack properties.

Meanwhile, in the present invention, the TREF analysis for polyethylene may be performed using a TREF equipment manufactured by Polymer Char. Specifically, a sample in a solution was prepared by dissolving the polyethylene in a solvent such as 1,2,4-trichlorobenzene, and after introducing the prepared sample into a TREF column, the initial temperature was lowered to 20° C., and then a constant heating rate 1 The concentration of the eluted polymer was measured by flowing 1,2,4-trichlorobenzene as a solvent through the column at a flow rate of 0.5 mL/min while raising the temperature to 120 °C at °C/min. A more specific measurement method will be described in detail in the following test examples.

As a result of the above TREF analysis, it is possible to obtain a TREF elution curve expressed as an elution amount (dW/dT) with respect to temperature, and confirm the first to third peaks corresponding to the first to third fractions in the above-described temperature range. I can. The identified first and third peaks mean that the polyethylene contains a semi-crystalline polymer corresponding to each peak.

In the present specification, "semi-crystalline" refers to a temperature rising elution fractionation (TREF), differential scanning calorimetry (DSC) or a first-order transition temperature, crystal melting temperature (Tm) or elution temperature measured by an equivalent technique. Refers to a polymer. The density, Tm, and elution temperature of semi-crystalline vary depending on the crystallinity. On the other hand, the term "amorphous" refers to a polymer without a crystal melting temperature as measured by elevated temperature elution fractionation (TREF), differential scanning calorimetry (DSC) or equivalent techniques.

In addition, the temperature at the highest point of each peak in the TREF elution curve is the elution temperature (Te), and is expressed as Te1, Te2, and Te3, respectively. The Te2 is lower than Te3 and is present at a higher temperature than Te1, specifically, the Te1 is 25 to 30°C, the Te2 is 40 to 65°C, and the Te3 is 80 to 100°C.

Polyethylene according to an embodiment of the present invention includes first to third semi-crystalline polymers corresponding to the first to third peaks and having different crystallinity.

Specifically, Te1 represents the elution temperature of the first semicrystalline polymer exhibiting low crystallinity, and is 25°C or higher, or 27°C or higher, or 28°C or higher, or 28.1°C or higher, 30°C or lower, or 29°C or lower, Or 28.5°C or less. In addition, Te2 represents the elution temperature of the second semicrystalline polymer having higher crystallinity than the first polymer, and is 40°C or higher, or 50°C or higher, or 60°C or higher, or 62°C or higher, and 65°C or lower , Or 63°C or less, or 62.5°C or less. Since the elution temperature and Te2 of the polymer chains exhibiting the intermediate level of crystallinity are as low as 65°C or less, the low crystal content is relatively high, so that they can be rapidly melted even at low temperatures, and as a result, the effect of improving the low-temperature sealing properties can be exhibited. have. In addition, Te3 represents the elution temperature of the third polymer having higher crystallinity than the second semi-crystalline polymer, and is 80°C or higher, or 90°C or higher, or 93°C or higher, 100°C or lower, or 95°C or lower, Or 94°C or less.

In addition, the fractional ratio (or content) of the entire polyethylene of the first to third fractions of polymer chains exhibiting different crystallinity may be determined by the integrated areas of the first to third peaks and their ratios, Each of these integrated areas can be derived by dividing the first to third peaks, for example, by each peak area according to a certain temperature area, and then obtaining the lower area, and the integral of each peak relative to the total area of each peak. The fractional ratio of each fraction corresponding to each peak may be determined by the ratio of the area.

When analyzed by this method, the polyethylene of one embodiment has a fractional ratio of the first fraction defined from the integral area of the first peak of 5% or more, more specifically 10% or more, or 11% or more, or 12% Or more, and may be 20% or less, or 15% or less, or 13% or less. This is, when converted based on the total weight of polyethylene, the content of the first semicrystalline polymer corresponding to the first fraction may be 5% by weight or more, and more specifically 10% by weight or more, 11% by weight or more, or 12% by weight or more. And, it corresponds to 20% by weight or less, 15% by weight or less, or 13% by weight or less. As described above, since the content of the first semi-crystalline polymer having the lowest crystallinity in the polyethylene is high, it can be rapidly melted at a low temperature, thereby improving the low-temperature sealing properties.

In addition, the polyethylene may have a weight average molecular weight (Mw) of 200,000 g/mol or more, more specifically 200,000 g/mol or more, or more than 200,000 g/mol, or 202,000 g/mol or more, or 205,000 g/mol or more, and may be 500,000 g/mol or less, or 300,000 g/mol or less, or 250,000 g/mol or less, or 210,000 g/mol or less, or 206,000 g/mol or less . As it has such a high molecular weight, the sealing strength may be improved even at low temperatures due to entanglement between polymer chains.

In addition, the number average molecular weight (Mn) of the first semicrystalline polymer is also as high as 50,000 g/mol or more, and more specifically, 50,000 g/mol or more, or 60,000 g/mol or more, or 70,000 g/mol or more, 100,000 g/mol or less, or 80,000 g/mol or less, or 75,000 g/mol or less, or 73,000 g/mol or less. In addition, the first semi-crystalline polymer has a high molecular weight distribution (Mw/Mn ratio) of 2 or more, or 2.3 or more, or 2.5 or more, or 2.8 or more, or 2.82 or more, and 3 or less, or 2.95 or less, or 2.93 or less. Can be indicated.

Meanwhile, in the present invention, the weight average molecular weight, number average molecular weight, and molecular weight distribution of the first semicrystalline polymer can be measured through gel permeation chromatography (GPC) analysis, and the specific measurement method thereof is described in the following test examples. It will be described in detail.

In addition, the polyethylene exhibits a density of ^{0.916 g/cm 3} or more when measured according to ASTM D1505 standards, along with the above-described crystal properties.

In general, the density of the olefin-based polymer is affected by the type and content of monomers used in polymerization, the degree of polymerization, and the like, and in the case of a copolymer, the content of comonomers is greatly influenced. In the present invention, it is possible to introduce a large amount of comonomer by using a catalyst composition containing a transition metal compound having a specific structure. As a result, polyethylene according to an embodiment of the present invention ^{exhibits a density of 0.916 g/cm 3} or more, and as a result, it can exhibit excellent mechanical properties and processability. More specifically, the polyethylene may have ^{a density of 0.916 g/cm 3} or more, 0.920 g/cm ³ or less, or 0.918 g/cm ³ or less, and maintain mechanical properties and impact strength through optimization of such a density range. The improvement effect can be further enhanced.

Furthermore, the polyethylene has an average number of short chain branches (SCB) per 1000 carbons in the polymer in the polymer region having a log Mw of 5.5 or more when analyzed by gel permeation chromatography (GPC-FTIR) combined with Fourier transform infrared spectroscopy, 35 It may be more than, more specifically 35 or more or 35.5 or more, or 36 or more, or 36.5 or more, 40 or less, or 39 or less, or 38.5 or less, or 38 or less. As such, the high number of SCBs in the polymer region reflects that the polymers in the polymer region contain a higher content of α-olefin repeating units, and as a result, the polymers in the polymer region form low crystals to improve the low-temperature sealing strength. It can show an effect that can be improved.

Furthermore, the polyethylene may have an average number of short-chain branches (SCBs) per 1000 carbons in the entire polymer of 18 or more, or 19 or more, or 20 or more, and 22 or less, or 21.5 or less. Such a high number of SCBs means that the content of comonomer is high, and as a result, an excellent low-temperature sealing strength improvement effect can be exhibited even when the density is lowered.

In the present invention, the number of short-chain branches (SCBs) in the polymer region having a log Mw of 5.5 or more and the number of SCBs in the polyethylene are expressed as average values after calculating each value from the GPC-FTIR analysis result. Is described in detail in the following test examples.

Further, the polyethylene may exhibit a narrow molecular weight distribution (MWD) of 3 or less, more specifically 2.75 or less, or 2.70 or less, and may exhibit a molecular weight distribution of 2 or more, or 2.5 or more, or 2.65 or more.

In general, when measuring TREF, having two or more Te means that two or more kinds of polymers having different branched chain contents of the polymer are mixed. In addition, when two or more polymers are mixed and present, the molecular weight distribution increases, and as a result, impact strength and mechanical properties decrease, and a blocking phenomenon occurs. However, polyethylene in the present invention exhibits three Tes and, as described above, has a narrow molecular weight distribution, thus exhibiting excellent impact strength and mechanical properties.

In addition, under the conditions satisfying the above molecular weight distribution range, the polyethylene has a number average molecular weight (Mn) of 35,000 g/mol or more, or 40,000 g/mol or more, or 42,000 g/mol or more, or 43,000 g/mol or more. , 50,000 g/mol or less, or 45,000 g/mol or less, or 44,000 g/mol or less, and a weight average molecular weight (Mw) of 100,000 g/mol or more, or 110,000 g/mol or more, or 112,000 g/mol or more, 130,000 g/mol or less, or 120,000 g/mol or less, or 115,000 g/mol or less or 114,000 g/mol or less.

Meanwhile, in the present invention, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are molecular weights in terms of polystyrene analyzed by gel permeation chromatography (GPC), and the molecular weight distribution (MWD) is Mw/Mn. Can be calculated from the ratio of The specific measurement method will be described in detail in the following experimental examples.

In addition, the polyethylene may satisfy any one or more of the following conditions (i) to (v), or two or more, or three or more, or four or more, or all five conditions:

(i) Melt index measured under conditions of 190° C. and 2.16 kg load according to ASTM D-1238: 0.8 to 2 g/10min,

(ii) melting temperature: 120 to 125°C,

(iii) crystallization temperature: 100 to 110°C,

(iv) heat of fusion in a temperature range of 0 to 130°C: 99.5 to 120 J/g, and

(v) According to the ASTM F1921 measurement method, the sealing start temperature under the 2N condition is 95°C or less, and the hot-tack strength at 100°C is 3.0N or more.

Specifically, the polyethylene has a melt index (MI) of 0.8 g/10min or more, or 0.9 g/10min or more, or 1 g/10min or more, measured according to ASTM D-1238 (condition E, 190°C, 2.16kg load) , 2 g/10min or less, or 1.8 g/10min or less, or 1.5 g/10min or less. By having a melt index in an optimum range together with a density in the above range, the polyethylene may exhibit improved processability while maintaining excellent mechanical properties.

In addition, the polyethylene has a high melting temperature of 120 to 125°C, and thus may exhibit excellent heat resistance. Specifically, the polyethylene may have a melting temperature (Tm) of 120°C or more, 125°C or less, or 122°C or less as measured by DSC.

In addition, the polyethylene may have a crystallization temperature (Tc) of 100°C or higher, 110°C or lower, or 105°C or lower, or 103°C or lower. This high crystallization temperature is due to the uniform distribution of comonomers in polyethylene, and by having the above-described temperature range, excellent structural stability can be exhibited.

In addition, the polyethylene was subjected to DSC at a temperature range of -50 to 190°C, and in the graph obtained as a result, heat of fusion confirmed as an integral value for the peak observed in the temperature range of 0 to 130°C; ΔH) may be 99.5 J/g or more, or 100.0 J/g or more, or 105 J/g or more, and 120 J/g or less, or 115 J/g or less. Accordingly, it can exhibit excellent heat resistance.

In the present invention, the melting temperature (Tm), crystallization temperature (Tc), and heat of fusion (ΔH) of the polyethylene can be measured using a differential scanning calorimeter (DSC), and the specific method is described below. It will be described in detail in an example.

Meanwhile, the above-described polyethylene may be a copolymer including an ethylene-based repeating unit and an α-olefin-based repeating unit, and in this case, the α-olefin-based repeating unit is 1-butene, 1-pentene, 4-methyl-1- Derived from an α-olefin having 3 to 20 carbon atoms such as pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, or 1-hexadecene It may be a repeating unit, and in consideration of the excellent impact strength of polyethylene, it may be appropriately a repeating unit derived from 1-hexene.

The polyethylene of the above-described embodiment may exhibit excellent low-temperature sealing strength characteristics. Specifically, the polyethylene has a sealing initiation temperature (SIT) of 95°C or less, or 93°C or less, or 90°C or less, as measured according to the ASTM F1921 measurement method, and a hot-tack strength at 100°C. (N/25mm)) is as high as 3.0N or more, or 3.2N or more.

Accordingly, it can be used in various fields and uses such as various packaging, construction, and household goods such as materials for automobiles, shoes, wires, toys, textiles, and medical use, for blow molding, extrusion molding, or injection molding. It can be usefully used, and is particularly useful as a high-speed packaging film.

On the other hand, it was confirmed that the above-described polyethylene can be manufactured by a manufacturing method using a specific catalyst system to be described later. Accordingly, according to another embodiment of the present invention, in the presence of a catalyst composition comprising a first transition metal compound represented by the following formula (1) and a second transition metal compound represented by the following formula (2), an ethylene monomer, and a carbon number of 3 Including the step of polymerizing the above α-olefin monomer, the hydrogen gas is added in an amount of 10 ppm or more and less than 200 ppm based on the total weight of the monomer including the ethylene monomer and the α-olefin monomer having 3 or more carbon atoms, There is provided a method for producing the above-described polyethylene, wherein the molar ratio of the α-olefin-based monomer to the ethylene monomer in the reactor (the molar ratio of the α-olefin-based monomer/ethylene monomer) is 0.25 or more:

[Formula 1]

In Formula 1,

R ₁ and R ₂ are each independently hydrogen, halogen, C _1-20 alkyl, C _2-20 alkenyl, C _1-20 alkoxy, C _2-20 alkoxyalkyl, C _6-20 aryl, C _7-20 alkyl Aryl, or C _7-20 arylalkyl,

X ₁ and X ₂ are each independently halogen or C _1-20 alkyl,

[Formula 2]

In Chemical Formula 2,

R ₃ and R ₄ are each independently hydrogen, halogen, C _1-20 alkyl, C _2-20 alkenyl, C _1-20 alkoxy, C _2-20 alkoxyalkyl, C _6-20 aryl, C _7-20 alkyl Aryl, or C _7-20 arylalkyl,

X ₃ and X ₄ are each independently halogen or C _1-20 alkyl.

In the transition metal compound included in the catalyst composition according to the embodiment, the substituents in Formulas 1 and 2 will be described in more detail as follows.

The halogen may be fluorine (F), chlorine (Cl), bromine (Br), or iodine (I).

C _1-20 alkyl can be straight chain, branched chain or cyclic alkyl. Specifically, C _1-20 alkyl is C _1-20 straight-chain alkyl; C _1-10 straight chain alkyl; C _1-5 straight chain alkyl; C _3-20 branched or cyclic alkyl; C _3-15 branched or cyclic alkyl; Or C _3-10 branched or cyclic alkyl. More specifically, C _1-20 alkyl may be methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl, n-pentyl, iso-pentyl or cyclohexyl.

C _2-20 alkenyl can be straight chain, branched chain or cyclic alkenyl. Specifically, C _2-20 alkenyl is C _2-20 straight alkenyl, C _2-10 straight alkenyl, C _2-5 straight alkenyl, C _3-20 branched alkenyl, C _3-15 branched alkenyl Kenyl, C _3-10 branched chain alkenyl, C _5-20 cyclic alkenyl or C _5-10 cyclic alkenyl. More specifically, C _2-20 alkenyl may be ethenyl, propenyl, butenyl, pentenyl or cyclohexenyl.

C _6-20 aryl can mean monocyclic, bicyclic or tricyclic aromatic hydrocarbons. Specifically, C _6-20 aryl may be phenyl, naphthyl or anthracenyl.

C _7-20 alkylaryl may mean a substituent in which at least one hydrogen of the aryl is substituted by alkyl. Specifically, the C _7-20 alkylaryl may be methylphenyl, ethylphenyl, n-propylphenyl, iso-propylphenyl, n-butylphenyl, iso-butylphenyl, tert-butylphenyl or cyclohexylphenyl.

C _7-20 arylalkyl may mean a substituent in which one or more hydrogens of alkyl are substituted by aryl. Specifically, the C _7-20 arylalkyl may be benzyl, phenylpropyl, or phenylhexyl.

C _1-20 alkoxy may be straight chain, branched chain or cyclic alkoxy. Specifically, examples of C _1-20 alkoxy include, but are not limited to, methoxy, ethoxy, n-butoxy, tert-butoxy, phenyloxy, and cyclohexyloxy.

C _2-20 alkoxyalkyl may mean a substituent in which at least one hydrogen of alkyl is substituted by alkoxy. Specifically, as C _2-20 alkoxyalkyl, methoxymethyl, ethoxymethyl, methoxyethyl, ethoxyethyl, butoxymethyl, butoxyethyl, butoxypropyl, butoxybutyl, butoxyheptyl, butoxy Hexyl and the like may be mentioned, but the present invention is not limited thereto.

In the catalyst composition according to the embodiment, R ₁ and R ₂ in Formula 1 are the same as or different from each other, and are each independently C _4-20 or C _4-12 straight-chain alkyl; _{Or it may be C 5-12} or C _6-10 straight-chain alkyl substituted with tert-butoxy _{, X 1} and X ₂ are the same as or different from each other, and each independently a halogen such as chloro; _{Or C 1-4} straight chain alkyl such as methyl; may be.

More preferably, in Formula 1, R ₁ and R ₂ are both C _6-10 straight chain alkyl substituted with tert-butoxy, or both are n-hexyl substituted with tert-butoxy, and X ₁ and X _{All 2} may be C _1-4 straight chain alkyl or methyl.

Specifically, the first transition metal compound represented by Formula 1 may be a compound represented by Formula 1a or Formula 1b, but is not limited thereto.

[Formula 1a]

[Formula 1b]

The first transition metal compound represented by the above structural formulas may be synthesized by applying known reactions, and a more detailed synthesis method may be referred to Examples.

In the catalyst composition according to the embodiment, R ₃ and R _{4 in Formula 1 are the same as or different from each other, and each independently C 3} -propyl, n-butyl, n-pentyl, or n-hexyl. ₁₂ straight-chain alkyl, X ₃ and X ₄ are the same as or different from each other, and each independently _{may be a C 1-4} straight-chain alkyl such as methyl or ethyl.

More preferably, in Formula 2, R ₃ and R ₄ may be all or C _4-6 straight-chain alkyl, and X ₃ and X ₄ may all be C _1-4 straight-chain alkyl or methyl.

Specifically, the second transition metal compound represented by Formula 2 may be a compound represented by Formula 2a or Formula 2b, but is not limited thereto.

[Formula 2a]

[Formula 2b]

The second transition metal compound represented by the above structural formulas may be synthesized by applying known reactions, and a more detailed synthesis method may be referred to Examples.

In the catalyst composition according to the embodiment, the first transition metal compound represented by Formula 1 contributes to making a low molecular weight linear copolymer, and the second transition metal compound represented by Formula 2 is a high molecular weight linear copolymer. It can contribute to the formation of coalitions. The catalyst composition may exhibit excellent support performance, catalytic activity, and high co-polymerization by using the first transition metal compound of low co-polymerization and the second transition metal compound of high co-polymerization together as a hybrid catalyst. Particularly, when ultra-low-density polyethylene is produced in a slurry process under such a catalyst composition, process stability is improved, and fouling problems that have occurred in the prior art can be prevented. In addition, polyethylene having excellent physical properties may be provided by using the catalyst composition.

In addition, in the catalyst composition, by controlling the mixing molar ratio of the first transition metal compound and the second transition metal compound, catalytic activity and copolymerization may be improved, and the molecular structure and physical properties of polyethylene may be more easily realized. . Specifically, the mixing molar ratio (A:B) of the first transition metal compound (A) and the second transition metal compound (B) may be 1:0.3 to 1:3.5, and when included in the above molar ratio, a high catalyst It can exhibit activity and copolymerization, and as a result, it is possible to more easily implement the structure and physical properties of the polyethylene as described above. In particular, in the case of producing ultra-low-density polyethylene in the slurry process under such a catalyst composition, the problem of lowering productivity and causing fouling due to melting or swelling of the conventional ultra-low-density polyethylene can be solved, thereby exhibiting excellent process stability .

If the molar ratio (A:B) of the first transition metal compound and the second transition metal compound is less than 1:0.3, it may be difficult to manufacture ultra-low density polyethylene as the copolymerization deteriorates, and if it exceeds 1:3.5, the molecule of the desired polymer The structure can be difficult to implement. More specifically, the molar ratio (A:B) of the first transition metal compound and the second transition metal compound in the catalyst composition may be 1:0.5 to 1:2, or 1:1 to 1:1.5.

Meanwhile, the catalyst composition may further include at least one of a carrier and a cocatalyst.

Specifically, the catalyst composition may further include a carrier supporting the first transition metal compound and the second transition metal compound. When the catalyst composition is used in the form of a supported catalyst, it is possible to further improve the morphology and physical properties of the polyethylene produced, and may be suitably used for slurry polymerization, bulk polymerization, and gas phase polymerization processes.

Specifically, as the carrier, moisture that interferes with the support of the transition metal compound on the carrier surface is removed, and instead, a carrier having a highly reactive hydroxy group, silanol group or siloxane group on the surface may be preferably used. The surface may be modified by calcination, or a drying process may be performed. For example, silica prepared by calcining silica gel, silica dried at high temperature, silica-alumina, and silica-magnesia may be used, and these are usually Na ₂ O, K ₂ CO ₃ , BaSO ₄ , and Mg(NO ₃ ) Oxide, carbonate, sulfate, and nitrate components such as _{2 may be contained.}

When calcining or drying the carrier, the temperature may be 200 to 600°C, and may be 250 to 600°C. If the calcination or drying temperature of the carrier is low below 200°C, there is a risk that the moisture on the surface and the cocatalyst may react because there is too much moisture remaining in the carrier, and the cocatalyst is carried by the excess hydroxyl groups. Although the rate may be relatively high, this requires a large amount of cocatalyst. In addition, if the drying or calcination temperature exceeds 600℃ and is too high, the surface area decreases as the pores on the surface of the carrier are combined, and a lot of hydroxyl groups or silanol groups disappear on the surface, and only siloxane groups remain, so that the reaction site with the cocatalyst There is a fear that the value will decrease.

The amount of hydroxy groups on the surface of the carrier can be controlled by a method and conditions for preparing the carrier or drying conditions such as temperature, time, vacuum or spray drying. When the amount of the hydroxy group is too low, the reaction site with the cocatalyst is small, and when the amount of the hydroxy group is too large, it may be due to moisture other than the hydroxy group present on the surface of the carrier particle. For example, the amount of hydroxy groups on the surface of the carrier may be 0.1 to 10 mmol/g or 0.5 to 5 mmol/g.

Among the above-described carriers, in the case of silica, since the transition metal compound is chemically bonded to and supported by the silica carrier, almost no catalyst is released from the carrier surface in the copolymerization process. As a result, in the case of producing polyethylene by slurry polymerization or gas phase polymerization, fouling of the reactor wall or polymer particles entangled with each other can be minimized, which is preferable.

In addition, when the catalyst composition is used in the form of a supported catalyst, the first and second transition metal compounds are 10 μmol or more, or 30 μmol or more, 500 μmol or less, based on 1 g of silica, per weight of the carrier, Alternatively, it may be supported in a content range of 100 μmol or less. When supported in the above content range, an appropriate supported catalytic activity may be exhibited, and thus it may be advantageous in terms of maintaining the activity of the catalyst and economical efficiency.

In addition, the catalyst composition may further include a cocatalyst to activate the transition metal compound as a catalyst precursor. The cocatalyst is an organometallic compound containing a group 13 metal, and is not particularly limited as long as it can be used when polymerizing olefins under a general metallocene catalyst. Specifically, the cocatalyst may be one or more compounds selected from the group consisting of compounds represented by the following Chemical Formulas 3 to 5.

[Formula 3]

-[Al(R ₁₁ )-O] _m-

In Chemical Formula 3,

R ₁₁ may be the same as or different from each other, and each independently halogen; Hydrocarbons of C _1-20; Or a halogen-substituted C _1-20 hydrocarbon;

m is an integer of 2 or more;

[Formula 4]

J(R ₁₂ ) ₃

In Chemical Formula 4,

R ₁₂ may be the same as or different from each other, and each independently halogen; Hydrocarbons of C _1-20; Or a halogen-substituted C _1-20 hydrocarbon;

J is aluminum or boron;

[Formula 5]

_{^{[EH] + [ZQ 4]}} - or _{^{[E] + [ZQ 4]}} -

In Chemical Formula 5,

E is a neutral or cationic Lewis base;

H is a hydrogen atom;

Z is a group 13 element;

Q may be the same as or different from each other, and each independently of one or more hydrogen atoms _{is substituted or unsubstituted with halogen, C 1-20} hydrocarbon, alkoxy or phenoxy, C _6-20 aryl group or C _1-20 It is an alkyl group.

_{Examples of the compound represented by Formula 3 include C 1-20} alkylaluminoxane-based compounds such as methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, or butylaluminoxane, and any one or two of them Mixtures of the above can be used.

In addition, examples of the compound represented by Formula 4 include trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, tripropyl aluminum, tributyl aluminum, dimethyl chloro aluminum, triisopropyl aluminum, tri-s-butyl aluminum, tricyclo Pentyl aluminum, tripentyl aluminum, triisopentyl aluminum, trihexyl aluminum, trioctyl aluminum, ethyl dimethyl aluminum, methyl diethyl aluminum, triphenyl aluminum, tri-p-tolyl aluminum, dimethyl aluminum methoxide, dimethyl aluminum ethoxide , Trimethyl boron, triethyl boron, triisobutyl boron, tripropyl boron, tributyl boron, and the like. More specifically, it may be selected from trimethyl aluminum, triethyl aluminum, and triisobutyl aluminum.

In addition, examples of the compound represented by Formula 5 include triethyl ammonium tetraphenyl boron, tributyl ammonium tetraphenyl boron, trimethyl ammonium tetraphenyl boron, tripropyl ammonium tetraphenyl boron, trimethyl ammonium tetra (p- Tolyl) boron, trimethyl ammonium tetra (o,p-dimethylphenyl) boron, tributyl ammonium tetra (p-trifluoromethylphenyl) boron, trimethyl ammonium tetra (p-trifluoromethylphenyl) boron, tributyl ammony Um tetrapentafluorophenyl boron, N,N-diethylanilinium tetraphenyl boron, N,N-diethylanilinium tetrapentafluorophenyl boron, diethyl ammonium tetrapentafluorophenyl boron, triphenyl Phosphonium tetraphenyl boron, trimethylphosphonium tetraphenyl boron, triethyl ammonium tetraphenyl aluminum, tributyl ammonium tetraphenyl aluminum, trimethyl ammonium tetraphenyl aluminum, tripropyl ammonium tetraphenyl aluminum, trimethyl ammonium tetra (p -Tolyl) aluminum, tripropyl ammonium tetra (p-tolyl) aluminum, triethyl ammonium tetra (o,p-dimethylphenyl) aluminum, tributyl ammonium tetra (p-trifluoromethylphenyl) aluminum, trimethyl ammonium Tetra (p-trifluoromethylphenyl) aluminum, tributylammonium tetrapentafluorophenyl aluminum, N,N-diethylanilinium tetraphenyl aluminum, N,N-diethylanilinium tetrapentafluorophenyl aluminum , Diethylammonium tetrapentafluorophenyl aluminum, triphenylphosphonium tetraphenyl aluminum, trimethylphosphonium tetraphenyl aluminum, tripropyl ammonium tetra (p-tolyl) boron, triethyl ammonium tetra (o,p-dimethyl) Phenyl) boron, tributyl ammonium tetra (p-trifluoromethylphenyl) boron, triphenyl carbonium tetra (p-trifluoromethylphenyl) boron, or triphenyl carbonium tetrapentafluorophenyl boron. And any one or a mixture of two or more of them may be used.

Among the above-described cocatalysts, when considering the fact that it can exhibit more excellent catalytic activity when used with the transition metal compound, the cocatalyst is a compound represented by Chemical Formula 3, more specifically, C _{1 such as methylaluminoxane. It} may be an alkylaluminoxane-based compound of -20. The alkylaluminoxane-based compound acts as a scavenger of hydroxyl groups present on the surface of the carrier to improve catalytic activity, and converts the halogen group of the catalyst precursor to a methyl group to promote chain growth during polymerization of polypropylene. Let it.

The cocatalyst may be supported in an amount of 0.1 g or more, or 0.5 g or more, and 20 g or less, or 10 g or less, based on 1 g of silica, for example, per weight of the carrier. When included in the above content range, it is possible to sufficiently obtain the effect of improving the catalytic activity according to the use of the cocatalyst and the effect of reducing the generation of fine particles.

In addition, when the catalyst composition includes both the carrier and the cocatalyst, the catalyst composition includes the steps of supporting the cocatalyst compound on the carrier; And supporting the transition metal compound on the carrier, wherein the transition metal compound is supported by the first transition metal compound and then the second transition metal compound is supported. It can be done, or vice versa. A supported catalyst having a structure determined according to such a supporting sequence may exhibit higher catalytic activity and excellent process stability in the manufacturing process of polyethylene.

In addition, the catalyst composition may be used in the form of a slurry or diluted in a solvent depending on the polymerization method, or may be used in the form of a mud catalyst mixed with a mixture of oil and grease.

When used as a slurry or diluted in a solvent, the solvent is an aliphatic hydrocarbon solvent having 5 to 12 carbon atoms suitable for the polymerization process of a propylene monomer, such as pentane, hexane, heptane, nonane, decane, and these Isomers and aromatic hydrocarbon solvents such as toluene and benzene, or hydrocarbon solvents substituted with chlorine atoms such as dichloromethane and chlorobenzene, and any one or a mixture of two or more of them may be used. In this case, the catalyst composition may further include the above-described solvent, and a small amount of water or air, which may act as a catalyst poison, may be removed by treating the solvent with a small amount of alkyl aluminum before use.

On the other hand, the polymerization process may be carried out as a continuous polymerization process, for example, a continuous solution polymerization process, a bulk polymerization process, a suspension polymerization process, a slurry polymerization process or an emulsion polymerization process, and various polymerizations known as polymerization reactions of olefinic monomers. The process can be employed.

Specifically, the polymerization reaction for the production of polyethylene may be performed by copolymerizing an ethylene monomer and an α-olefin-based monomer as a comonomer using one continuous slurry polymerization reactor or a loop slurry reactor. However, according to the method of one embodiment, in order to more effectively control the molecular weight distribution, it is more appropriate to polymerize the olefin-based monomer by continuous bulk-slurry polymerization or gas phase polymerization. In particular, the polymerization reaction may be carried out in a slurry phase polymerization in a hydrocarbon-based solvent (eg, an aliphatic hydrocarbon-based solvent such as hexane, butane, or pentane). As the first and second transition metal compounds according to the present invention exhibit excellent solubility in aliphatic hydrocarbon-based solvents, they are stably dissolved and supplied to the reaction system, so that the polymerization reaction can proceed effectively.

Specifically, as the α-olefin monomer, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-itocene, and the like may be used, and among them, 1-hexene may be used. Accordingly, in the slurry polymerization, the ethylene and 1-hexene may be polymerized to produce ultra-low density polyethylene.

Meanwhile, during the polymerization reaction, the molar ratio of the α-olefin monomer/ethylene monomer in the reactor is 0.25 or more.

The molar ratio of the monomers introduced into the reactor before the polymerization reaction and the molar ratio of the monomers present in the reactor during the polymerization reaction may vary depending on the catalytic reactivity. In the present invention, by controlling the molar ratio of the ethylene monomer and the α-olefin monomer present (or remaining) in the reactor within the above range during the polymerization reaction, the resulting copolymer has the above crystal structure and physical properties, especially 0.916 g/cm ^It can show sufficient stiffness by showing a density of 3 or more. However, when the molar ratio of the α-olefin monomer/ethylene monomer is less than 0.25, it is difficult to prepare and implement polyethylene having the above-described crystal structure and physical properties. More specifically, the molar ratio of the α-olefin monomer/ethylene monomer in the reactor may be 0.25 or more, or 0.26 or more, 0.3 or less, or 0.28 or less, or 0.27 or less, and in this case, the density of the copolymer is 0.916 to 0.920 g/ By maintaining the cm ³ level, better stiffness can be exhibited.

On the other hand, the molar ratio of the ethylene monomer and the α-olefin monomer in the reactor can be calculated using the gas chromatograph after measuring each concentration. The specific measurement method will be described in detail in the following test examples.

In addition, the temperature during the polymerization reaction may be 70 to 200 ℃. If the polymerization reaction temperature is less than 70°C, the polymerization rate and productivity may be lowered, and if it exceeds 200°C, there is a concern that a fouling phenomenon in the reactor may occur. In consideration of the ease and fairness of realizing the above-described physical properties of the polyethylene according to the polymerization temperature control, the polymerization reaction may be carried out at a temperature of 80° C. or more and 150° C. or less.

In addition, the pressure during the polymerization reaction may be 20 to 50 bar to ensure optimum productivity. It is possible to manufacture polyethylene with better efficiency within the above range. More specifically, it may be performed at a pressure of 20 bar or more and 40 bar or less.

In addition, during the polymerization reaction, hydrogen gas may be introduced for the purpose of controlling the molecular weight and molecular weight distribution of polyethylene. At this time, the hydrogen gas serves to suppress the rapid reaction of the transition metal compound at the initial stage of polymerization and terminate the polymerization reaction. Accordingly, by controlling the use and amount of hydrogen gas, polyethylene having the molecular structure and physical properties described above can be effectively manufactured.

The hydrogen gas may be added in an amount of 10 ppm or more and less than 200 ppm based on the total weight of the monomer including ethylene and α-olefin.

When introduced under the above-described conditions, the ethylene/α-olefin polymer to be produced can realize the physical properties in the present invention. If the content of hydrogen gas is less than 10ppm, the polymerization reaction is not uniformly terminated, making it difficult to manufacture polyethylene having the desired physical properties.If the content of hydrogen gas is more than 200ppm, the termination reaction occurs too quickly to produce polyethylene with an excessively low molecular weight. There is a risk of becoming. More specifically, the hydrogen gas may be added in an amount of 10 ppm or more, or 15 ppm or more, 180 ppm or less, or 150 ppm or less, or 100 ppm or less, or 50 ppm or less, or 30 ppm or less based on the total weight of the monomer.

In addition, trialkyl aluminum such as triethyl aluminum may be optionally further added during the polymerization reaction.

When moisture or impurities are present in the polymerization reactor, a part of the catalyst is decomposed. The trialkyl aluminum acts as a scavenger to capture moisture or impurities in the reactor or moisture contained in the monomer in advance. The activity of the catalyst used in the preparation can be maximized, and as a result, a homopolyethylene having excellent physical properties, particularly a narrow molecular weight distribution, can be produced more efficiently. Specifically, in the trialkylaluminum, alkyl is as defined above, specifically C _{1-20 alkyl, and more specifically C 1-6} straight or branched chain alkyl, such as methyl, ethyl, isobutyl, etc. I can. The trialkylaluminum (based on 1M) may be added in an amount of 300 ppm or more, or 400 ppm or more, 600 ppm or less, or 500 ppm or less, based on the total weight of the monomer including ethylene and α-olefin, and the tree of this content range Upon polymerization reaction in the presence of alkylaluminum, homopolyethylene having excellent strength characteristics can be more easily prepared.

In addition, an organic solvent may be further used as a reaction medium or diluent in the polymerization reaction. Such an organic solvent may be used in an amount such that slurry polymerization or the like can be properly performed in consideration of the content of the olefinic monomer.

Polyethylene prepared by the above-described manufacturing method may exhibit improved low-temperature sealing properties due to an increase in the content and molecular weight of the low crystalline polymer, and when used as a packaging film, it may exhibit increased hot-tack sealing properties.

Accordingly, according to another embodiment of the present invention, a film including the above-described polyethylene, more specifically, a film for high-speed packaging is provided.

The film may be prepared and used according to a conventional method, except that the above-described polyethylene is included as a main component.

Hereinafter, a preferred embodiment is presented to aid the understanding of the present invention. However, the following examples are provided for easier understanding of the present invention, and the contents of the present invention are not limited thereto.

<Preparation of hybrid supported catalyst>

Synthesis Example 1

Silica (SP952 manufactured by Grace Davison) was dehydrated and dried under vacuum for 12 hours at a temperature of 200°C.

3.0 kg of a toluene solution was put in a 20L sus high-pressure reactor, and 1000 g of the dried silica (SP952 manufactured by Grace Davison) was added, followed by stirring while raising the temperature of the reactor to 40°C. After sufficiently dispersing silica for 60 minutes, 8 kg of a 10 wt% methylaluminoxane (MAO)/toluene solution was added, followed by stirring at 200 rpm for 12 hours. After raising the reactor temperature to 60℃, dissolve 0.01mmol of the compound represented by Formula 1b in a solution state, and then react for 2 hours. After dissolving 0.01mmol of the compound represented by Formula 2a in a solution state, add and react for 2 hours. Was added. After stopping the stirring and settling for 30 minutes, the reaction solution was decanted. 3.0 kg of hexane was added to the reactor, the hexane slurry was transferred to filter dry, and the hexane solution was filtered. It was dried under reduced pressure at 50° C. for 4 hours to prepare a supported catalyst.

(1b)

(2a)

Synthesis Example 2

_{0.14 mol of a Grignard reagent tBu-O-(CH 2} )6MgCl solution was obtained from the reaction between the tBu-O-(CH ₂ ) ₆ Cl compound and Mg(0) in diethyl ether (Et _{2 O) solvent.} . _{MeSiCl 3} compound (24.7 ml, 0.21 mol) was added thereto at -100°C, stirred at room temperature for 3 hours or more, and then the filtered solution was vacuum dried (tBu-O-(CH ₂ ) ₆ SiMeCl ₂ To obtain a compound (yield 84%), a solution of tBu-O-(CH ₂ ) ₆ SiMeCl ₂ (7.7 g, 0.028 mol) dissolved in hexane (50 ml) at -78° C. was dissolved in fluorenyllithium (4.82 g). , 0.028 mol)/hexane (150 ml) solution was slowly added over 2 hours, the white precipitate (LiCl) was filtered off, the desired product was extracted with hexane, and all volatiles were vacuum-dried to form a pale yellow oil (tBu- O-(CH ₂ ) ₆ )SiMe (9-C ₁₃ H ₁₀ ) to obtain a compound (yield 99%).

THF solvent (50 ml) was added thereto, _{and after reacting with a C 5} H ₅ Li (2.0 g, 0.028 mol)/THF (50 ml) solution at room temperature for 3 hours or more, all volatile substances were vacuum-dried and extracted with hexane. Thus, a final ligand, orange oil (tBu-O-(CH ₂ ) ₆ )(CH ₃ )Si(C ₅ H ₅ )(9-C ₁₃ H ₁₀ ) compound was obtained (yield 95%). The structure of the ligand was confirmed through 1H NMR.

In addition, (tBu-O-(CH ₂ ) ₆ )(CH ₃ )Si(C ₅ H ₅ )(9-C ₁₃ H ₁₀ )(12g, 0.028mol)/THF(100mol) solution at -78℃ Add 2 equivalents of n-BuLi and react for more than 4 hours while raising it to room temperature.The orange solid form (tBu-O-(CH ₂ ) ₆ )(CH ₃ )Si(C ₅ H ₅ Li)(9-C ₁₃ H ₁₀ Li) of the compound was obtained (yield 81%). In addition, a dilithium salt (2.0g, 4.5mmol)/ether (30ml) solution in a suspension solution of _{ZrCl 4 (1.05g, 4.50mmol)/ether (30ml) at -78℃} Was slowly added and further reacted at room temperature for 3 hours. All volatile substances were vacuum-dried, and dichloromethane solvent was added to the obtained oily liquid substance and filtered off. After vacuum drying the filtered solution, hexane was added to induce a precipitate. The obtained precipitate was washed several times with hexane and racemic-(tBu-O-(CH ₂ ) ₆ )(CH ₃ )Si(C ₅ H ₄ )(9-C ₁₃ H ₉ )ZrCl ₂ compound ( 3) was obtained (yield 54%).

Subsequently, in the same manner as in Synthesis Example 1, except that the compound (3) synthesized above was used instead of the compound of Formula 2a in Synthesis Example 1, compound (1b) and compound (3) were A hybrid supported supported catalyst was prepared.

<Production of ethylene/α-olefin copolymer>

Example 1

In the presence of the hybrid supported catalyst prepared above, ethylene-1-hexene was slurry-polymerized under the conditions shown in Table 1 below.

At this time, the polymerization reactor was a continuous polymerization reactor that is an isobutane slurry loop process, the reactor volume was 140L, and the reaction flow rate was operated at about 7m/s. Gases (ethylene, hydrogen) required for polymerization and 1-hexene, which is a comonomer, are constantly and continuously injected, and individual flow rates are adjusted according to the target product. The concentrations of all gases and 1-hexene, a comonomer, were confirmed by on-line gas chromatograph. The supported catalyst was introduced as an isobutane slurry, the reactor pressure was maintained at about 40 bar, and the polymerization temperature was carried out at about 85°C.

Examples 2 to 4, and Comparative Examples 1 to 4

An ethylene/1-hexene copolymer was prepared by performing the same method as in Example 1, except for changing to the conditions described in Table 1 below.

Comparative Example 5

A commercially available ethylene/1-hexene copolymer (Exxon XP8318™, gas phase polymerization) was used.

Comparative Example 6

Commercially available ethylene/1-hexene copolymer (Exxon XP8656ML™, gas phase polymerization) was used.

Comparative Example 7

Commercially obtained ethylene/1-hexene copolymer (Daelim BO1801EN™, gas phase polymerization) was used.

	Example 1	Example 2	Example 3	Example 4	Comparative Example 1	Comparative Example 2	Comparative Example 3	Comparative Example 4
catalyst	Synthesis Example 1	Synthesis Example 1	Synthesis Example 1	Synthesis Example 1	Synthesis Example 1	Synthesis Example 1	Synthesis Example 1	Synthesis Example 2
Catalytic activity* (kgPE/gCat)	6.0	6.2	6.2	6.4	6.0	6.5	5.8	6.7
Polymerization process	Slurry polymerization	Slurry polymerization	Slurry polymerization	Slurry polymerization	Slurry polymerization	Slurry polymerization	Slurry polymerization	Slurry polymerization
Polymerization temperature (℃)	85	85	85	85	85	85	85	85
H 2 input (ppm)	15	15	20	50	5	200	15	20
Ethylene input (kg/h)	25	25	25	25	25	25	25	25
Comonomer	1-hexene	1-hexene	1-hexene	1-hexene	1-hexene	1-hexene	1-hexene	1-hexene
Comonomer input (kg/h)	3.0	3.5	3.0	3.0	2.8	3.5	2.5	4.5
Molar ratio of comonomer/ethylene**	0.25	0.27	0.25	0.26	0.24	0.26	0.20	0.32

* Catalytic activity (kgPE/gCat): After measuring the weight of the catalyst (Cat) used in the polymerization reaction of the Example or Comparative Example and the weight of the polymer (PE) prepared from the polymerization reaction, respectively, prepared based on the weight of the catalyst used The activity of the catalyst was calculated as the weight ratio of the resulting polymer.

** Molar ratio of comonomer/ethylene: In the above table, the molar ratio of comonomer/ethylene is the molar ratio of comonomer (1-hexene) to ethylene present in the slurry reactor during the polymerization reaction, and ethylene and 1-hexene using a gas chromatograph. Each concentration of was measured, and the molar ratio was calculated from the results.

In addition, the concentration of each monomer using the gas chromatograph was measured using a gas chromatography (7890B GC) equipped with _{an Agilent Al 2} O _{3 KCl column having a length of 50 m and an inner diameter of 0.53 mm, and a carrier gas of 12 mL.} It was high-purity helium flowing at a rate of /min, the injection port temperature was 200°C, and was injected using a separation mode (10:1).

Test Example 1

Through temperature rise elution fractionation (TREF) analysis, the elution temperature (Te), and the content of the low crystalline polymer, that is, the first semicrystalline polymer at 25 to 30°C, were measured, and also through gel permeation chromatography analysis. The number average molecular weight (Mn) and the weight average molecular weight (Mw) were measured, respectively.

(1) TREF analysis

PolymerChar's TREF equipment was used, and 1,2,4-trichlorobenzene was used as a solvent and the measurement was performed in the range of 20°C to 120°C. Specifically, 30 mg of polyethylene of the Example or Comparative Example was dissolved in 20 ml of 1,2,4-trichlorobenzene solvent at 135° C. for 30 minutes and then stabilized at 95° C. for 30 minutes to prepare each sample. The prepared sample was introduced into a TREF column, cooled to 20° C. at a temperature drop rate of 0.5° C./min, and held for 2 minutes. Thereafter, while heating from 20°C to 120°C at a constant heating rate of 1°C/min, 1,2,4-trichlorobenzene as a solvent was flowed through the column at a flow rate of 0.5 mL/min, and the concentration of the eluted polyethylene was measured.

From the resultant TREF elution curve, the elution temperature (Te) of polyethylene was confirmed, and the content of the first semicrystalline polymer at Te 25 to 30° C. was calculated based on the total weight of polyethylene (% by weight).

(2) GPC analysis

Gel permeation chromatography (GPC) was used to measure the number average molecular weight (Mn) and weight average molecular weight (Mw) of the low crystalline polymer, that is, the semicrystalline polymer at Te 25 to 30°C.

Polymer Laboratories PLgel MIX-B 300 mm length column was used, and measured using a Waters PL-GPC220 instrument. At this time, the evaluation temperature was 160° C., 1,2,4-trichlorobenzene was used as a solvent, and the flow rate was measured at a rate of 1 mL/min. The sample was prepared at a concentration of 10 mg/10 mL, and then supplied in an amount of 200 μL. Using a calibration curve formed using polystyrene standards, the values of Mw and Mn were derived. The molecular weight (g/mol) of the polystyrene standard was 2,000 / 10,000 / 30,000 / 70,000 / 200,000 / 700,000 / 2,000,000 / 4,000,000 / 10,000,000.

The above analysis results are shown in Table 2 below and FIGS. 1 to 7.

1 to 4 are graphs showing analysis results according to TREF for polyethylenes prepared in Example 1 and Comparative Examples 5 to 7, respectively, and FIGS. 5 to 7 are respectively in Example 1 and Comparative Examples 5 and 6 It is a graph showing the GPC analysis results of the first semi-crystalline polymer in the prepared polyethylene.

		Example				Comparative example
		One	2	3	4	One	2	3	4	5	6	7
Te1 (℃)		28.5	28.1	28.0	28.1	28.0	28.0	28.1	28.1	28.1	28.1	25.1
Te2 (℃)		62.5	62.0	62.6	62.2	63.5	60.2	62.3	-	68.1	67.5	73.9
Te3 (℃)		93.8	93.0	93.7	93.5	94.0	92.8	93.0	87.4	95.8	95.7	85.0
Te4 (℃)		-	-	-	-	-	-	-	-	-	-	95.8
Te 1st semi-crystalline polymer of 25~30℃	content (weight%)	12.0	13.0	12.2	12.5	8.0	9.5	6.5	1.2	3.9	4.9	2.1
	Mn (g/mol)	70,000	73,000	70,000	70,000	300	305	300	300	302	315	295
	Mw (g/mol)	205,000	206,000	204,000	202,000	320	310	310	310	325	329	309
	Mw/Mn	2.93	2.95	2.92	2.90	1.07	1.02	1.03	1.03	1.08	1.04	1.05

Test Example 2

Physical properties of the ethylene/α-olefin copolymers prepared in Examples and Comparative Examples were measured by the following method, and the results are shown in Tables 3, 8, and 11 below.

(1) Melt Index (MI) (g/10min): The melt index (MI2.16) was measured under a load of 2.16 kg at 190°C according to ASTM D 1238, and the weight of the polymer melted for 10 minutes (g) (g). ).

(2) Density (Density, g/cm ³ ): It was measured according to ASTM D1505.

(3) Melting temperature (Tm), crystallization temperature (Tc), and ΔH (0-130°C): Tm, Tc, and ΔH were measured using a Differential Scanning Calorimeter (DSC), respectively.

Specifically, it was measured using a DSC 2920 (TA instrument) as a differential scanning calorimeter (DSC). After heating the copolymer in Example or Comparative Example to 190° C., it was maintained for 5 minutes, and the temperature was lowered to -50° C., and then the temperature was increased again. At this time, the rate of rise and fall of the temperature were adjusted to 10°C/min, respectively. The melting temperature (Tm) was taken as the maximum point of the endothermic peak measured in the section where the second temperature rises.

In addition, the crystallization temperature (Tc) was performed in the same manner as in the measurement of the melting temperature, and the maximum point of the exothermic peak was taken as the crystallization temperature from the curve that appeared while decreasing the temperature.

In addition, ΔH is the integral value for the peak observed in the temperature range of 0 to 130°C in the graph obtained by performing DSC at a temperature range of -50 to 190°C in the same manner as in the measurement of the melting temperature As a result, the heat of fusion value was confirmed (unit: J/g).

(4) Number average molecular weight (Mn), weight average molecular weight (Mw), molecular weight distribution (MWD): The number average molecular weight (Mn) and the weight average molecular weight (Mw) were respectively measured using gel permeation chromatography (GPC). , The weight average molecular weight was divided by the number average molecular weight to calculate the molecular weight distribution (Mw/Mn).

Specifically, a Polymer Laboratories PLgel MIX-B 300 mm length column was used, and the measurement was performed using a Waters PL-GPC220 instrument. At this time, the evaluation temperature was 160° C., 1,2,4-trichlorobenzene was used as a solvent, and the flow rate was 1 mL/min. The polymer sample was prepared at a concentration of 10 mg/10 mL, and then supplied in an amount of 200 μL. The values of Mw and Mn were derived using a calibration curve formed using polystyrene standards. The molecular weight (g/mol) of the polystyrene standard was 2,000 / 10,000 / 30,000 / 70,000 / 200,000 / 700,000 / 2,000,000 / 4,000,000 / 10,000,000.

(5) Average number of SCBs: Through gel permeation chromatography (GPC-FTIR) analysis combined with Fourier transform infrared spectroscopy, the number of SCBs in the copolymer and the number of SCBs in the polymer region with log Mw of 5.5 or more were calculated and averaged. Expressed as a value.

Specifically, each copolymer prepared in Examples and Comparative Examples was analyzed by gel permeation chromatography (GPC) in the same manner as in 4), and the log value (log Mw) of the weight average molecular weight (Mw) was x The molecular weight distribution curve of the polymer chains constituting the copolymer was derived, with the axis as the axis and the molecular weight distribution (dw_dlogM) with respect to the log value as the y axis.

In addition, each copolymer was analyzed by FT-IR to derive a distribution curve of the number of SCBs per 1000 carbon atoms (right y-axis; SCB per 1000TC) according to the weight average molecular weight (x-axis) of the polymer chains.

From these derivation results, the number of SCBs per 1000 carbon atoms in the polymer and the number of SCBs per 1000 carbon atoms in the copolymer in the polymer region of log Mw 5.5 or more were calculated, respectively, and expressed as an average value.

	Example				Comparative example
	One	2	3	4	One	2	3	4	5	6	7
Density (g/cm 3 )	0.918	0.916	0.918	0.918	0.918	0.918	0.921	0.918	0.918	0.916	0.918
MI (g/10min)	1.0	1.0	1.5	2.0	0.4	10.5	1.0	1.0	1.0	0.5	1.0
Tm (℃)	121.5	120.0	120.5	120.2	122.5	119.5	122.0	118.0	122.1	122.7	122.3
Tc (℃)	102.1	101.5	102.0	101.7	105.1	100.0	102.0	105.0	107.4	105.8	63.2/106.4
△H(0~130℃)(J/g)	115.0	105.0	112.0	110.0	118.5	114.0	119.5	114.0	111.9	99.2	141.2
Mn (g/mol)	43,000	44,000	40,000	38,000	52,000	16,000	41,000	42,000	32,000	34,000	29,000
Mw (g/mol)	112,000	114,000	110,000	107,000	152,000	48,000	111,000	100,000	110,000	131,000	99,000
MWD	2.65	2.70	2.65	2.60	2.70	2.80	2.75	2.52	3.41	3.82	3.41
Average number of SCBs (#1000C)	20.0	21.5	20.5	20.7	18.5	19.0	16.5	17.0	20.4	21.7	17.5
The average number of SCBs in the polymer region of log Mw 5.5 or higher (#1000C)	36.5	38.0	36.7	37.0	32.5	34.0	32.5	11.5	27.4	32.5	26.1

8 to 11 are graphs showing SCB content according to polyethylene molecular weight obtained as a result of GPC-FTIR analysis of polyethylenes prepared in Example 1 and Comparative Examples 5 to 7, respectively.

Comparing FIGS. 8 to 11, it can be seen that in Example 1, the SCB content in the ultra-high molecular weight region is high, as a result, the low crystal content is high, and the low crystal has a high molecular weight.

From the above experimental results, in the case of Examples 1 and 2, it can be confirmed that the SCB content is high in the ultrahigh molecular weight region as compared to the copolymers of Comparative Examples 4, 5 and 7 having the same level of MI and density, From this, it can be expected to exhibit excellent low-temperature sealing strength characteristics.

Test Example 3

For the ethylene/1-hexene copolymer prepared in the above Examples and Comparative Examples, According to the ASTM F1921 measurement method using a J&B hot tack tester (Hot tacker 4000), the sealing initiation temperature (SIT) and hot-tack strength (N/25mm) as low-temperature sealing strength were measured, The results are shown in Table 4 and Fig. 12.

<Measurement conditions>

Pressure: 0.275 N / mm ²

Sealing time: 0.5 sec

Cooling time: 0.1 sec

Peeling speed: 200 mm/s

Width: 25 mm

Thickness: 50~60㎛

		Example				Comparative example
		One	2	3	4	One	2	3	4	5	6	7
SIT(℃), 2N		90.0	87.0	89.0	87.0	97.0	95.0	100.1	115.0	107.5	98.0	120.0
Hot-tack Strength (N/25mm)	90℃	2.0	2.5	2.1	2.5	-	-	-	-	-	-	-
	95℃	3.0	3.2	3.0	3.0	1.5	2.0	-	-	-	1.5	-
	100℃	3.2	3.8	3.1	3.3	2.3	2.3	2.0	-	1.1	2.6	-

In Table 4, "-" means not measured.

12 is a graph showing the results of measuring the low temperature sealing strength of the polyethylene prepared in Example 1 and Comparative Examples 5 to 7.

As a result of the experiment, in the case of Examples 1 and 2, the sealing initiation temperature (SIT) in the 2N condition was as low as 90°C or less compared to the comparative examples, and the sealing strength was high in a wide melting temperature.

Claims (18)

1. It includes an ethylene repeating unit and an α-olefin repeating unit,

   The density measured according to ASTM D1505 is 0.916 g/cm ³ or more,

   When analyzed by the temperature rise elution fractionation method, the three elution temperatures of Te1, Te2 and Te3 respectively correspond to the elution temperatures of the first to third semicrystalline polymers in a temperature range of 20 to 120°C, and the Te2 is a temperature higher than that of Te3. Is lower and the temperature is higher than Te1,

   The Te1 is 25 to 30 ℃,

   The first semi-crystalline polymer has a weight average molecular weight of 200,000 g/mol or more, and is contained in an amount of 5% by weight or more based on the total weight of polyethylene.
2. The method of claim 1,

   The first semi-crystalline polymer has a weight average molecular weight of 200,000 to 500,000 g/mol, and is contained in an amount of 10 to 20% by weight based on the total weight of polyethylene.
3. The method of claim 1,

   The Te2 is 40 to 65 ℃, Te3 is 80 to 100 ℃, polyethylene.
4. The method of claim 1,

   The polyethylene, when analyzed by gel permeation chromatography combined with Fourier transform infrared spectroscopy, has an average number of short-chain branches per 1000 carbons in the polymer in a polymer region having a log Mw of 5.5 or more, 35 or more.
5. The method of claim 1,

   Polyethylene, wherein the average number of short-chain branches per 1000 carbons in the polyethylene is 18 to 22.
6. The method of claim 1,

   The polyethylene has a molecular weight distribution of 3 or less.
7. The method of claim 1,

   The polyethylene has a number average molecular weight of 35,000 to 50,000 g/mol, and a weight average molecular weight of 100,000 to 130,000 g/mol, polyethylene.
8. The method of claim 1,

   The polyethylene is a polyethylene that satisfies at least one of the following conditions (i) to (v):

   (i) Melt index measured under conditions of 190° C. and 2.16 kg load according to ASTM D-1238: 0.8 to 2 g/10min,

   (ii) melting temperature: 120 to 125°C,

   (iii) crystallization temperature: 100 to 110°C,

   (iv) heat of fusion in a temperature range of 0 to 130°C: 99.5 to 120 J/g, and

   (v) According to the ASTM F1921 measurement method, the sealing start temperature at 2N condition is 95°C or less, and the hot-tack strength at 100°C is 3.0N or more.
9. The method of claim 1,

   The α-olefin is 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene or these Polyethylene, comprising a mixture of.
10. The method of claim 9,

    The α-olefin is 1-hexene, polyethylene.
11. In the presence of a catalyst composition comprising a first transition metal compound represented by the following formula (1) and a second transition metal compound represented by the following formula (2), hydrogen gas is introduced into the reactor, and an ethylene monomer and an α-olefin monomer having 3 or more carbon atoms Including the step of polymerization reaction,

    The hydrogen gas is added in an amount of 10 ppm or more and less than 200 ppm with respect to the total weight of the monomer including an ethylene monomer and an α-olefin-based monomer having 3 or more carbon atoms,

    During the polymerization reaction, the method for producing polyethylene according to claim 1, wherein the molar ratio of the α-olefin-based monomer to the ethylene monomer present in the reactor is 0.25 or more:

    [Formula 1]

    

    In Formula 1,

    R ₁ and R ₂ are each independently hydrogen, halogen, C _1-20 alkyl, C _2-20 alkenyl, C _1-20 alkoxy, C _2-20 alkoxyalkyl, C _6-20 aryl, C _7-20 alkyl Aryl, or C _7-20 arylalkyl,

    X ₁ and X ₂ are each independently halogen or C _1-20 alkyl,

    [Formula 2]

    

    In Chemical Formula 2,

    R ₃ and R ₄ are each independently hydrogen, halogen, C _1-20 alkyl, C _2-20 alkenyl, C _1-20 alkoxy, C _2-20 alkoxyalkyl, C _6-20 aryl, C _7-20 alkyl Aryl, or C _7-20 arylalkyl,

    X ₃ and X ₄ are each independently halogen or C _1-20 alkyl.
12. The method of claim 11,

    R ₁ and R ₂ are each independently C _4-12 straight-chain alkyl; _{Or C 5-9} straight-chain alkyl substituted with tert-butoxy, the production method.
13. The method of claim 11,

    R ₃ and R ₄ are each independently C _3-12 straight-chain alkyl,

    X ₃ and X ₄ are each independently C _1-4 straight-chain alkyl.
14. The method of claim 11,

    The first transition metal compound is a compound represented by the following Formula 1a or Formula 1b, a preparation method:

    [Formula 1a]

    

    [Formula 1b]

    

    .
15. The method of claim 11,

    The second transition metal compound is a compound represented by the following formula 2a or 2b, a preparation method:

    [Formula 2a]

    

    [Formula 2b]

    

    .
16. The method of claim 11,

    The first transition metal compound and the second transition metal compound are contained in a molar ratio of 1:0.3 to 1:3.5.
17. The method of claim 11,

    The catalyst composition further comprises at least one of a carrier and a cocatalyst.
18. A film comprising the polyethylene according to any one of claims 1 to 10.

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