KR20240041262A - Polyethylene composition and biaxially stretched film comprising the same - Google Patents

Abstract

The present invention relates to a polyethylene composition that maintains excellent mechanical properties and is suitable for biaxially stretched films due to excellent stretching stability and high shrinkage resistance.

Description

Polyethylene composition and biaxially stretched film comprising the same {POLYETHYLENE COMPOSITION AND BIAXIALLY STRETCHED FILM COMPRISING THE SAME}

The present invention relates to a polyethylene composition suitable for biaxially stretched films that maintains excellent mechanical properties, has high shrinkage resistance, printability, and transparency.

Thin film products made from linear low density polyethylene (LLDPE) and/or high density polyethylene (HDPE) are widely used in packaging applications such as merchandise bags, grocery bags, food and specialty packaging, and industrial liners. It is being used. In this application, shrink film, which allows packaging while maintaining the shape of the product, is mainly used to protect the product from touch when displayed.

In particular, among these shrink films, biaxially stretched polymer films are widely used for packaging purposes due to their excellent mechanical properties, productivity, and printability. Commercially available packaging films generally use BOPP (bi-axially oriented polypropylene), BOPET (biaxially-oriented polyethylene terephthalate), or BOPA (biaxially-oriented polyamide) for the printing layer, and LLDPE film for the sealing layer. This form of composite material is not recyclable, and the demand for single materials is increasing due to the spread of packaging recycling regulations. Therefore, research and development is underway to manufacture a single-material packaging film by replacing the film of the printing layer with a biaxially-oriented polyethylene (BOPE) film.

However, commercial polyethylene (PE) resin does not have sufficient stretching stability, and phenomena such as fracture and melting occur during stretching, making it difficult to apply the biaxial stretching process. In order to ensure stretching stability, products in the form of polyethylene compositions containing resins with low density and high melt index are being developed. However, the above composition shows low rigidity, shrinkage, and impact resistance, making it unsuitable as a PE resin for biaxially stretched films.

Accordingly, there is a need for a method of selecting a PE resin with a molecular structure favorable for stretching, selecting an appropriate composition, and providing a PE composition for biaxial stretching that exhibits stretching stability during biaxial stretching while exhibiting satisfactory film mechanical properties. .

The present invention is to provide a polyethylene composition capable of producing a biaxially stretched film that maintains excellent mechanical properties, productivity, and stretching stability, and has high shrinkage resistance, printability, and transparency, and a biaxially stretched film containing the same.

One embodiment of the present invention is a polyethylene composition comprising at least one type of ethylene-alpha olefin copolymer, wherein the polyethylene composition contains a highly crystalline fraction eluted at 90° C. or higher when analyzed by cross fractionation chromatography (CFC). A polyethylene composition having a main chain weight average molecular weight (Mw _{main, T≥90°C} ) of 150,000 g/mol or less is provided.

In addition, another embodiment of the invention provides a biaxially stretched film comprising the polyethylene composition of the above embodiment.

Hereinafter, a polyethylene composition and a biaxially stretched film according to embodiments of the invention will be described in detail.

The terminology used herein is only used to describe exemplary embodiments and is not intended to limit the invention.

Singular expressions include plural expressions unless the context clearly dictates otherwise.

In this specification, terms such as “comprise,” “comprise,” or “have” are used to describe implemented features, numbers, steps, components, or combinations thereof, and include one or more other features, numbers, or steps. , does not exclude the possibility of components, combinations or additions thereof.

In addition, the terms "about", "substantially", etc. used throughout this specification are used to mean at or close to that value when manufacturing and material tolerances inherent in the stated meaning are presented, and are used herein to To facilitate understanding, precise or absolute figures are mentioned and are used to prevent unscrupulous infringers from taking unfair advantage of the disclosure.

Additionally, in this specification, (co)polymer includes both homo-polymer and co-polymer.

Unless otherwise defined herein, “copolymerization” may mean block copolymerization, random copolymerization, graft copolymerization, or alternating copolymerization, and “copolymer” may mean block copolymer, random copolymer, graft copolymer, or alternating copolymerization. It can mean merging.

Since the present invention can make various changes and take various forms, specific embodiments will be illustrated and described in detail below. However, this does not limit the present invention to the specific disclosed form, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention.

Hereinafter, the present invention will be described in detail.

polyethylene composition

The polyethylene composition of one embodiment is a polyethylene composition containing at least one type of ethylene-alpha olefin copolymer, and the main chain weight average molecular weight of the highly crystalline fraction eluted at 90° C. or higher when analyzed by cross fractionation chromatography (CFC) A polyethylene composition is provided, wherein (Mw _{main, T≥90°C} ) is 150000 g/mol or less.

For reference, in this specification, “part by weight” refers to a relative concept expressed as a ratio of the weight of the remaining material based on the weight of a certain material. For example, in a mixture containing 50 g of substance A, 20 g of substance B, and 30 g of substance C, the amounts of substance B and substance C would each be 40 parts by weight based on 100 parts by weight of substance A. parts by weight and 60 parts by weight.

Meanwhile, “% by weight” refers to an absolute concept expressed as a percentage of the weight of a certain material out of the total weight. In the above example mixture, the contents of material A, material B, and material C are 50% by weight, 20% by weight, and 30% by weight, respectively, based on 100% of the total weight of the mixture.

The polyethylene composition of one embodiment includes a first ethylene-alphaolefin copolymer that has excellent flowability and can provide stretchability by applying a specific metallocene catalyst, which will be described later, and a second ethylene-alphaolefin that has excellent mechanical properties. By adjusting the balance between mechanical properties and stretchability through blending of copolymers, it maintains mechanical properties, productivity, and stretching stability equivalent to or superior to existing ones, and is used to manufacture biaxially stretched films with high shrinkage resistance, printability, and transparency. It has suitable characteristics.

These polyethylene compositions, for example, each made with a metallocene catalyst, (a) have a density of 0.870 g/cm ³ to 0.920 g/cm ³ and a melt index (MI _2.16 , 190 ^o C, 2.16 kg load); A first ethylene-alphaolefin copolymer having a value of 3.0 g/10min to 10.0 g/10min; and (b) a second ethylene-alphaolefin having a density of 0.930 g/cm ³ to 0.960 g/cm ³ and a melt index (MI _2.16 , 190 ^o C, 2.16 kg load) of 0.2 g/10min to 2.0 g/10min. It may contain copolymers.

In particular, the polyethylene composition of one embodiment includes the first and second ethylene-alpha olefin copolymers in a predetermined composition, and thus has desirable crystal properties, at 90° C. or higher when analyzed by cross fractionation chromatography (CFC). The eluted highly crystalline fraction may have a main chain weight average molecular weight (Mw _{main, T≥90°C} ). More specifically, the polyethylene composition of one embodiment may exhibit partial crystallinity including a crystalline portion including a lamellar structure and an amorphous portion between the crystalline portions. Depending on these desirable crystal properties, that is, the ratio of molecules included in the amorphous portion and able to connect between lamellae, the elasticity, etc. of the polyethylene composition may be affected.

The polyethylene composition of one embodiment can exhibit excellent stretching properties and stretching stability according to the above-described desirable crystal properties, and can exhibit excellent mechanical properties and transparency when manufactured as a biaxially stretched film.

In a more specific example, the polyethylene composition of one embodiment has a main chain weight average molecular weight (Mw _{main, T≥90°C} ) of the highly crystalline fraction eluted at 90°C or higher when analyzed by cross fractionation chromatography (CFC) of 150,000. It may be less than or equal to 50000 g/mol to 150000 g/mol.

Preferably, the main chain weight average molecular weight (Mw _{main, T≥90°C} ) of the highly crystalline fraction is 140,000 g/ mol or less, or 135000 g/mol or less, or 130000 g/mol or less, or 125000 g/mol or less, or 120000 g/mol or less, or 118000 g/mol or less, or 115000 g/mol or less. However, the main chain weight average molecular weight (Mw _{main, T≥90°C} ) of the highly crystalline fraction is 6000 g/mol or more, or 7000 g/mol or more, or 80000 g/mol, in terms of maintaining the excellent mechanical properties of the film. or more, or more than 90000 g/mol, or more than 100000 g/mol, or more than 105000 g/mol, or more than 110000 g/mol.

In addition, in the polyethylene composition, when analyzed by cross fractionation chromatography (CFC), the content ratio (TREF _{, T≥90°C} ) of the highly crystalline fraction eluted at 90°C or higher is 50% or more of the total weight of all eluted fractions. It may be 50% or more and 95% or less. Specifically, the content ratio of the highly crystalline fraction (TREF _{, T≥90°C} ) may be 50.2% or more, 50.5% or more, or 50.9% or more of the total weight of the total eluted fraction, and if necessary, 90% or less, or 85%. It may be less than or equal to 80%, or less than or equal to 75%, or less than or equal to 70%, or less than or equal to 65%.

In addition, in the polyethylene composition, when analyzed by cross fractionation chromatography (CFC), the content ratio (TREF _{, T<90°C) of the low- to medium-crystalline fraction eluted at less than 90 ℃} is 50% or less of the total weight of all eluted fractions. It may be 5% or more and 50% or less. Specifically, the content ratio (TREF _{, T<90°C} ) of the medium-low crystalline fraction may be 49.8% or less, 49.5% or less, or 49.1% or less of the total weight of the total eluted fraction, and if necessary, 10% or more, or 15%. It may be more than 20%, or more than 25%, or more than 30%, or more than 35%.

In the present invention, the specific test method related to cross fractionation chromatography (CFC) analysis is as described in Test Example 2, which will be described later. However, the cross fractionation chromatography (CFC) analysis is not limited to this and may be measured by other methods known in the art to which the present invention pertains.

As an example, cross-fraction chromatography (CFC) analysis, including temperature rising elution temperature (TREF) analysis and GPC-IR analysis, was performed on the polyethylene composition in the following manner, and the The main chain weight average molecular weight of the highly crystalline fraction (Mw _{main, T≥90℃} ), the content ratio of the highly crystalline fraction eluted above 90℃ (TREF _{, T≥90℃} ), and the low- to medium-crystalline fraction eluted below 90℃ The content ratio (TREF _{, T<90℃} ) can be measured.

- Measurement conditions (including TREF and GPC-IR analysis)

- Analysis equipment: Polymer Char CFC (Detector: Integrated Detector IR5 MCT)

- Sample preparation and input: Put 32 mg of polyethylene composition in a 10 mL vial and place it in the autosampler, add 8 mL of 1,2,4-trichlorobenzene (TCB), and then cool to 90 degrees Celsius at 160 ^o C. Dissolve for minutes, extract after Nitrogen purge, and load into a temperature rising elution fractionation column (TREF column).

- Crystallization: The sample previously loaded on the TREF column is set to 100 ℃, then cooled from 100 ℃ to 35 ℃ at a rate of 0.5 ℃/min.

- Temperature rising elution temperature (TREF) analysis: The previously crystallized sample is held by raising the temperature at 1 ℃ intervals from 35 ℃ to 120 ℃, and the fractions eluting at each temperature are analyzed for 25 minutes. Specifically, extraction and analysis are performed at 35°C for 25 minutes, then extraction and analysis are performed by increasing the temperature at 1°C intervals, and finally extraction and analysis are performed at 120°C for 25 minutes.

- GPC-IR analysis: In the TREF analysis, the fractions eluted at each temperature were moved to the GPC column of the GPC (PL-GPC220) device, the molecular weight of the eluted molecules was measured, and the PerkinElmer Spectrum connected to the GPC (PL-GPC220) was used. 100 Using FT-IR, the number of short-chain branches (scb) of molecules eluted at each temperature is measured.

- Main chain average molecular weight of the highly crystalline fraction (Mw _main , _{T≥90 ℃} ) Calculation: main chain excluding the short-chain branch part among the fractions eluted above 90 ℃ previously confirmed through CFC analysis ) The weight average molecular weight (Mw _{main, T≥90°C} , g/mol) of the portion is calculated according to Equation 1 below.

[Equation 1]

In equation 1 above,

M _T,i and C _T,i are the weight average molecular weight (g/mol) and concentration of each fraction eluted at each temperature through the CFC analysis,

n ^scb _T,i is the number of branched chains (scb) of each fraction eluted at each temperature through the previous CFC analysis,

M _scb is the weight average molecular weight (g/mol) of the branched chain (scb) of each fraction eluted at each temperature through CFC analysis.

Specifically, the content ratio of the highly crystalline fraction (TREF _{, T≥90°C} ) of the polyethylene composition is the content ratio of the highly crystalline fractions eluted at 90°C or higher, based on the total weight of all eluted fractions obtained through CFC analysis as described above. This is a value calculated as a percentage (%). In addition, the content ratio of the highly crystalline fraction (TREF _{, T<90°C} ) is the content ratio of the low- to medium-crystalline fractions eluted below 90°C, based on the total weight of all eluted fractions obtained through CFC analysis as described above, as a percentage ( It is a value calculated in %).

Meanwhile, the polyethylene composition may have a stress relaxation time (RT ₁₂₀ °C) of 4.0 seconds or less or 0.02 seconds to 4.0 seconds or less at 120°C. Preferably, the stress relaxation time (RT _{120°C) at 120°C} is 3.8 seconds or less, or It may be 3.5 seconds or less, or 3.2 seconds or less, or 3.0 seconds or less, or 2.5 seconds or less. However, in terms of maintaining the excellent mechanical properties of the film, the stress relaxation time at 120°C (RT _120°C ) is 0.1 second or more, or 0.5 second or more, or 1.0 second or more, or 1.2 second or more, or It may be at least 1.5 seconds, or at least 1.8 seconds, or at least 2.0 seconds.

The stress relaxation time of the polyethylene composition is measured by measuring the viscosity of the polyethylene composition under each temperature condition and angular frequency conditions of 0.05 rad/s to 500 rad/s using a rotational rheometer. Afterwards, this viscosity can be obtained by calculating the stress relaxation time (relaxation time, seconds) of polyethylene using a specific cross model. Alternatively, the stress relaxation time (relaxation time, seconds) can be calculated under specific temperature conditions through an Arrhenius plot based on the stress relaxation time (relaxation time, seconds) for each temperature measured as described above. . For example, the method for measuring the stress relaxation time of the polyethylene composition is as described in Test Example 2, which will be described later. However, the stress relaxation time of the polyethylene composition is not limited to this and can be measured by other methods known in the art to which the present invention pertains.

Meanwhile, the polyethylene composition may have a density of 0.928 g/cm ³ to 0.942 g/cm ³ . Preferably, the density is at least 0.929 g/cm ³ , or at least 0.930 g/cm ³ , or at least 0.931 g/cm ³ and at most 0.940 g/cm ³ , or at most 0.939 g/cm ³ , or at least 0.938 g/cm 3 It may be cm ³ or less.

This density (g/cm ³ ) can be measured using a density gradient pipe according to the American Society for Testing and Materials ASTM D 1505 standard. For example, the method for measuring this density (g/cm ³ ) is as described in Test Examples 1 and 2 described later.

Additionally, the polyethylene composition may have a melt index (MI _2.16 , 190 ^o C, 2.16 kg load) of 0.6 g/10min to 1.5 g/10min. Preferably, the melt index (MI _2.16 , 190 ^o C, 2.16 kg load) is 0.65 g/10min or more, or 0.7 g/10min or more, or 0.75 g/10min or more, and 1.4 g/10min or less, or 1.3 g. /10min or less, or 1.2 g/10min or less.

The melt index (MI _2.16 ) can be measured under a load of 2.16 kg at 190 ^o C according to the American Society for Testing and Materials standard ASTM D 1238 (Condition E, 190 ^o C, 2.16 kg). As an example, the method of measuring the melt index (MI _2.16 ) is as described in Test Examples 1 and 2 described later.

In addition, the polyethylene composition has a number average molecular weight Mn of 25,000 g/mol or more or 25,000 g/mol or more to 500,000 g/mol or less, and a weight average molecular weight Mw of 105,000 g/mol or more or 105,000 g/mol or more to 1,000,000 g. /mol or less, and the molecular weight distribution Mw/Mn may be 5.0 or less or 0.5 or more to 5.0 or less.

The molecular weight distribution Mw/Mn of the polyethylene composition may be 4.8 or less, or 4.5 or less, or 4.3 or less, or 4.0 or less, or 3.8 or less. Additionally, the molecular weight distribution Mw/Mn may be 1.0 or more, or 1.2 or more, or 1.5 or more, or 1.8 or more, or 2.0 or more, or 2.5 or more, or 2.8 or more, or 3.0 or more.

The above-mentioned weight average molecular weight (Mw) and number average molecular weight (Mn) are converted values for standard polystyrene measured using gel permeation chromatography (GPC). However, the weight average molecular weight is not limited to this and can be measured by other methods known in the technical field to which the invention pertains. As an example, the method of measuring the weight average molecular weight (Mw) and number average molecular weight (Mn) is as described in Test Examples 1 and 2 described later.

As an example, the weight average molecular weight (Mw) and number average molecular weight (Mn) of the polyethylene composition were determined according to the ASTM D 6474 standard of the American Society for Testing and Materials using gel permeation chromatography (GPC, manufactured by Water). It can be measured accordingly. Specifically, as a gel permeation chromatography (GPC) device, a Waters PL-GPC220 device can be used, and a Polymer Laboratories PLgel MIX-B 300 mm long column can be used. At this time, the measurement temperature is 160 ℃, 1,2,4-trichlorobenzene can be used as a solvent, and the flow rate can be applied at 1 mL/min. A sample of the polyethylene composition was pretreated by dissolving it in 1,2,4-Trichlorobenzene (1,2,4-Trichlorobenzene) containing 0.0125% BHT at 160 ^o C for 10 hours using a GPC analysis device (PL-GP220), and 10 mg/10 It can be prepared at a concentration of mL and then supplied in an amount of 200 μL. Here, the values of Mw and Mn can be derived using a calibration curve formed using a polystyrene standard specimen. The weight average molecular weight of polystyrene standard specimens is 2000 g/mol, 10000 g/mol, 30000 g/mol, 70000 g/mol, 200000 g/mol, 700000 g/mol, 2000000 g/mol, 4000000 g/mol, 10000000 g. Nine types of /mol can be used.

Additionally, the polyethylene composition may have a melting point Tm of 125°C to 129°C, a crystallization temperature Tc of 112°C to 115°C, and a crystallinity degree Xc of 35% to 48%.

The melting point Tm, crystallization temperature Tc, and crystallinity Xc can be measured using a differential scanning calorimeter (DSC). For example, the method of measuring the melting point Tm, crystallization temperature Tc, and crystallinity Xc is as described in Test Example 2, which will be described later.

For example, the melting point Tm, crystallization temperature Tc, and crystallinity Xc of the polyethylene composition can be measured using a Differential Scanning Calorimeter (DSC, device name: DSC Q20, manufacturer: TA instrument). First, the temperature was raised and the polyethylene composition sample was heated at 10 ℃/min to 180 ℃ (Cycle 1), isothermalized at 180 ℃ for 5 minutes, cooled to 0 ℃ at 10 ℃/min, and then isothermalized at 30 ℃ for 5 minutes. Then heat again at 10 ℃/min to 180 ℃ (Cycle 2). In the DSC curve obtained through this, the temperature of the maximum point of the endothermic peak is measured as the melting temperature (Tm, ℃), and the temperature of the maximum point of the exothermic peak is measured as the crystallization temperature (Tc, ℃). At this time, the melting temperature (Tm) and crystallization temperature (Tc) are shown as the results of measurements in the section (Cycle 2) where the second temperature rises and falls, respectively.

In addition, in the section where the second temperature rises (Cycle 2), Heat of Fusion △Hm is calculated as the area of the melting peak, and this is divided by H ⁰ m = 293.6 J/g, which is the theoretical value when the crystallinity is 100%, to calculate the crystallinity ( Xc, %) can be calculated.

Meanwhile, the polyethylene composition according to the embodiment includes (a) the first ethylene-alpha olefin copolymer in an amount of more than 0 to 40% by weight or less, and (b) the second ethylene-alpha olefin copolymer in an amount of 60% by weight or less. It may contain from more than 100% by weight to less than 100% by weight.

Preferably, (a) the first ethylene-alphaolefin copolymer is 5% by weight or more, or 10% by weight or more, or 15% by weight or more, and 38% by weight or less, or 35% by weight or less, or 30% by weight. It may be included below.

In addition, (b) the second ethylene-alpha olefin copolymer is 62% by weight or more, or 65% by weight or more, or 70% by weight or more, and 85% by weight or less, or 90% by weight or less, or 95% by weight or less. may be included.

Preferably, by combining the first and second ethylene-alpha olefin copolymers in an appropriate amount, the composition of one embodiment can satisfy an appropriate crystal structure, etc., and thus can satisfy all the excellent physical properties described above. there is.

In addition, in the polyethylene composition, the first and second ethylene-alpha olefin copolymers may each be a copolymer of ethylene and an alpha olefin having 3 to 20 carbon atoms. In a more specific example, ethylene, 1-butene, It can be a copolymer of 1-hexene or 1-octene. In a specific example, these first and second ethylene-alphaolefin copolymers may be the same or different polymers. For example, (a) the first ethylene-alphaolefin copolymer is ethylene/1- It is an octene copolymer, and the second ethylene-alpha olefin copolymer (b) may be an ethylene/1-hexene copolymer.

(a) First ethylene-alpha olefin copolymer

First, in the polyethylene composition according to one embodiment of the present invention, (a) the first ethylene-alpha olefin copolymer has excellent flowability, excellent stretching stability and high shrinkage resistance, so it can provide characteristics suitable for manufacturing a biaxially stretched film. .

Specifically, the first ethylene-alpha olefin copolymer (a) has a density of 0.870 g/cm ³ to 0.920 g/cm ³ and a melt index (MI _2.16 , 190 ^o C, 2.16 kg load) of 3.0 g/cm 3 10 min to 10.0 g/10 min.

Preferably, the first ethylene-alphaolefin copolymer (a) has a density of 0.880 g/cm ³ or more, or 0.890 g/cm ³ or more, or 0.895 g/cm ³ or more, and 0.915 g/cm ³ or less. , or 0.910 g/cm ³ or less, or 0.905 g/cm ³ or less.

In addition, the first ethylene-alpha olefin copolymer (a) has a melt index (MI _2.16 , 190 ^o C, 2.16 kg load) of 3.5 g/10min or more, or 4.0 g/10min or more, or 4.5 g/10min or more. and may be 9.0 g/10min or less, or 8.0 g/10min or less, or 7.0 g/10min or less.

And, the (a) first ethylene-alpha olefin copolymer has a number average molecular weight Mn of 20,000 g/mol or more or 20,000 g/mol or more to 35,000 g/mol or less, and a weight average molecular weight Mw of 60,000 g/mol or more. to less than 95000 g/mol, and the molecular weight distribution Mw/Mn may be 2.0 or more to less than 3.5.

Preferably, the number average molecular weight Mn of the first ethylene-alphaolefin copolymer (a) may be 22000 g/mol or more, or 25000 g/mol or more, or 28000 g/mol or more, and may be 34000 g/mol or less. , or 33000 g/mol or less, or 32000 g/mol or less.

In addition, the weight average molecular weight Mw of the (a) first ethylene-alpha olefin copolymer may be 62000 g/mol or more, or 64000 g/mol or more, or 65000 g/mol or more, and may be 90000 g/mol or less, or It may be 80000 g/mol or less, or 70000 g/mol or less.

In addition, the molecular weight distribution Mw/Mn of the first ethylene-alphaolefin copolymer (a) may be 2.1 or more, or 2.2 or more, or 2.3 or more, and 3.2 or less, or 3.0 or less, or 2.8 or less, or 2.5 or less.

The (a) first ethylene-alpha olefin copolymer may have at least one of the above-mentioned properties, and may have all of the above-mentioned properties to exhibit excellent mechanical strength.

Here, the method for measuring each physical property of the first ethylene-alpha olefin copolymer (a) is the same as previously described for the polyethylene composition, and detailed description is omitted.

On the other hand, the first ethylene-alphaolefin copolymer (a) is 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dode together with ethylene. It includes one or more alpha-olefins selected from the group consisting of cenene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene, and mixtures thereof.

Additionally, the first ethylene-alpha olefin copolymer (a) may be an ethylene/1-octene copolymer.

When the (a) first ethylene-alpha olefin copolymer is the above-mentioned copolymer, the above-mentioned physical properties can be more easily realized. However, the types of the (a) first ethylene-alpha olefin copolymer are not limited to the above-mentioned types, and various types known in the technical field to which the present invention pertains may be provided as long as they can exhibit the above-mentioned physical properties.

Meanwhile, the first ethylene-alpha olefin copolymer (a) having the above physical properties may be prepared in the presence of a metallocene catalyst.

Specifically, the (a) first ethylene-alphaolefin copolymer can be prepared by copolymerizing ethylene and a comonomer in the presence of a catalyst composition containing a first metallocene compound represented by the following formula (1).

[Formula 1]

In Formula 1,

M ¹ is a Group 4 transition metal;

X ^{1 and} A hydrocarbyloxyhydrocarbyl group with 2 to 30 carbon atoms, -SiH ₃ , a hydrocarbyl (oxy)silyl group with 1 to 30 carbon atoms, a sulfonate group with 1 to 30 carbon atoms, or a sulfone group with 1 to 30 carbon atoms;

Z is -O-, -S-, -NR _a -, or -PR _a -,

R _a is hydrogen, any one of a hydrocarbyl group having 1 to 20 carbon atoms, a hydrocarbyl (oxy)silyl group having 1 to 20 carbon atoms, and a silylhydrocarbyl group having 1 to 20 carbon atoms;

T is or ego,

T ¹ is C, Si, Ge, Sn or Pb,

Q ¹ and Q ² are the same or different from each other, and are each independently hydrogen, a hydrocarbyl group with 1 to 30 carbon atoms, a hydrocarbyloxy group with 1 to 30 carbon atoms, a hydrocarbyloxyhydrocarbyl group with 2 to 30 carbon atoms, -SiH ₃ , any one of a hydrocarbyl (oxy)silyl group having 1 to 30 carbon atoms, a hydrocarbyl group having 1 to 30 carbon atoms substituted with halogen, and -NR _b R _c ,

R _b and R _c are each independently hydrogen and a hydrocarbyl group having 1 to 30 carbon atoms, or are connected to each other to form an aliphatic or aromatic ring;

C ¹ is any one of the ligands represented by the following formulas 1a to 1d,

[Formula 1a]

[Formula 1b]

[Formula 1c]

[Formula 1d]

In Formulas 1a to 1d,

Y is O or S,

R ¹ to R ⁶ are the same as or different from each other, and are each independently hydrogen, a hydrocarbyl group having 1 to 30 carbon atoms, or a hydrocarbyloxy group having 1 to 30 carbon atoms.

In this specification, unless there is a special limitation, the following terms may be defined as follows.

Hydrocarbyl group is a monovalent functional group obtained by removing a hydrogen atom from hydrocarbon, and includes alkyl group, alkenyl group, alkynyl group, aryl group, aralkyl group, aralkenyl group, aralkynyl group, alkylaryl group, alkenylaryl group, and alkyl group. It may include a nylaryl group, etc. And, the hydrocarbyl group having 1 to 30 carbon atoms may be a hydrocarbyl group having 1 to 20 carbon atoms or a hydrocarbyl group having 1 to 10 carbon atoms. For example, the hydrocarbyl group may be straight chain, branched chain, or cyclic alkyl. More specifically, the hydrocarbyl group having 1 to 30 carbon atoms is methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, tert-butyl group, n-pentyl group, n-hexyl group. Straight-chain, branched-chain, or cyclic alkyl groups such as actual group, n-heptyl group, and cyclohexyl group; Alternatively, it may be an aryl group such as phenyl, biphenyl, naphthyl, anthracenyl, phenanthrenyl, or fluorenyl. Additionally, it may be alkylaryl such as methylphenyl, ethylphenyl, methylbiphenyl, and methylnaphthyl, and may also be arylalkyl such as phenylmethyl, phenylethyl, biphenylmethyl, and naphthylmethyl. Additionally, it may be alkenyl such as allyl, allyl, ethenyl, propenyl, butenyl, and pentenyl.

A hydrocarbyloxy group is a functional group in which a hydrocarbyl group is bonded to oxygen. Specifically, a hydrocarbyloxy group having 1 to 30 carbon atoms may be a hydrocarbyloxy group having 1 to 20 carbon atoms or a hydrocarbyloxy group having 1 to 10 carbon atoms. For example, the hydrocarbyloxy group may be straight chain, branched chain, or cyclic alkyl. More specifically, the hydrocarbyloxy group having 1 to 30 carbon atoms is methoxy group, ethoxy group, n-propoxy group, iso-propoxy group, n-butoxy group, iso-butoxy group, tert-butoxy group, and n-pentoxy group. , straight-chain, branched-chain, or cyclic alkoxy groups such as n-hexoxy group, n-heptoxy group, and cyclohexoxy group; Alternatively, it may be an aryloxy group such as a phenoxy group or naphthalenoxy group.

Hydrocarbyloxyhydrocarbyl group is a functional group in which one or more hydrogens of the hydrocarbyl group are replaced with one or more hydrocarbyloxy groups. Specifically, a hydrocarbyloxyhydrocarbyl group having 2 to 30 carbon atoms may be a hydrocarbyloxyhydrocarbyl group having 2 to 20 carbon atoms or a hydrocarbyloxyhydrocarbyl group having 2 to 15 carbon atoms. For example, the hydrocarbyloxyhydrocarbyl group may be straight chain, branched chain, or cyclic alkyl. More specifically, the hydrocarbyloxyhydrocarbyl group having 2 to 30 carbon atoms is methoxymethyl group, methoxyethyl group, ethoxymethyl group, iso-propoxymethyl group, iso-propoxyethyl group, iso-propoxyhexyl group, tert-part. Alkoxyalkyl groups such as toxymethyl group, tert-butoxyethyl group, and tert-butoxyhexyl group; Or it may be an aryloxyalkyl group such as a phenoxyhexyl group.

Hydrocarbyl (oxy)silyl group is a functional group in which 1 to 3 hydrogens of -SiH ₃ are replaced with 1 to 3 hydrocarbyl groups or hydrocarbyloxy groups. Specifically, the hydrocarbyl (oxy) silyl group having 1 to 30 carbon atoms may be a hydrocarbyl (oxy) silyl group having 1 to 20 carbon atoms, 1 to 15 carbon atoms, 1 to 10 carbon atoms, or 1 to 5 carbon atoms. More specifically, the hydrocarbyl (oxy)silyl group having 1 to 30 carbon atoms is an alkyl group such as methylsilyl group, dimethylsilyl group, trimethylsilyl group, dimethylethylsilyl group, diethylmethylsilyl group, or dimethylpropylsilyl group. silyl group; Alkoxysilyl groups such as methoxysilyl group, dimethoxysilyl group, trimethoxysilyl group, or dimethoxyethoxysilyl group; It may be an alkoxyalkyl silyl group such as methoxydimethylsilyl group, diethoxymethylsilyl group, or dimethoxypropylsilyl group.

A silylhydrocarbyl group having 1 to 20 carbon atoms is a functional group in which one or more hydrogens of the hydrocarbyl group are replaced with a silyl group. The silyl group may be -SiH ₃ or a hydrocarbyl (oxy)silyl group. Specifically, a silylhydrocarbyl group having 1 to 20 carbon atoms may be a silylhydrocarbyl group having 1 to 15 carbon atoms or a silylhydrocarbyl group having 1 to 10 carbon atoms. More specifically, the silylhydrocarbyl group having 1 to 20 carbon atoms is a silylalkyl group such as -CH ₂ -SiH ₃ ; Alkylsilylalkyl groups such as methylsilylmethyl group, methylsilylethyl group, dimethylsilylmethyl group, trimethylsilylmethyl group, dimethylethylsilylmethyl group, diethylmethylsilylmethyl group, or dimethylpropylsilylmethyl group; Or it may be an alkoxysilylalkyl group such as dimethylethoxysilylpropyl group.

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

The sulfonate group has the structure of -O-SO ₂ -R _d , where R _d may be a hydrocarbyl group having 1 to 30 carbon atoms. Specifically, the sulfonate group having 1 to 30 carbon atoms may be a methane sulfonate group or a phenyl sulfonate group.

The sulfone group having 1 to 30 carbon atoms has the structure of -R ^e' -SO ₂ -R ^e" , where R ^e' and R ^e" are the same or different from each other and are each independently any one of the hydrocarbyl groups having 1 to 30 carbon atoms. You can. Specifically, the sulfone group having 1 to 30 carbon atoms may be a methylsulfonylmethyl group, a methylsulfonylpropyl group, a methylsulfonylbutyl group, or a phenylsulfonylpropyl group.

In this specification, the fact that two adjacent substituents are connected to each other to form an aliphatic or aromatic ring means that the atom(s) of the two substituents and the atoms (atoms) to which the two substituents are bonded are connected to each other to form a ring. do. Specifically, examples where R _b and R _c or R _b' and R c _' of -NR _b R _c or -NR _b' R _c' are linked together to form an aliphatic ring include a piperidinyl group, etc. Examples of R _b and R _c or R _{b '} and R c _' of -NR b R _c or -NR _b' R _c' being connected to each other to form an aromatic ring include a pyrrolyl group, etc. It can be exemplified.

And, the Group 4 transition metal may be titanium (Ti), zirconium (Zr), hafnium (Hf), or rutherphodium (Rf), and specifically, titanium (Ti), zirconium (Zr), or hafnium (Hf). It may be, and more specifically, it may be zirconium (Zr) or hafnium (Hf), but it is not limited thereto.

Additionally, the Group 13 element may be boron (B), aluminum (Al), gallium (Ga), indium (In), or thallium (Tl), and may specifically be boron (B) or aluminum (Al). and is not limited to this.

The above-mentioned substituents are optionally hydroxy groups within the range of achieving the same or similar effects as the desired effect; halogen; hydrocarbyl group; hydrocarbyloxy group; A hydrocarbyl group or hydrocarbyloxy group containing one or more heteroatoms from groups 14 to 16; silyl group; Hydrocarbyl (oxy)silyl group; Phosphine group; phosphide group; Sulfonate group; and may be substituted with one or more substituents selected from the group consisting of a sulfone group.

In this specification, means a bond connected to another substituent.

Specifically, in Formula 1, Z is -NR _a -, R _a may be a hydrocarbyl group having 1 to 10 carbon atoms, and specifically, R _a is a straight-chain or branched alkyl group having 1 to 6 carbon atoms. It may be, and more specifically, it may be a tert-butyl group.

And, in Formula 1, T is and T ¹ is carbon (C) or silicon (Si), and Q ¹ and Q ² may each independently be hydrogen, a hydrocarbyl group with 1 to 30 carbon atoms, or a hydrocarbyloxy group with 1 to 30 carbon atoms. Specifically, Q ¹ and Q ² may each be a hydrocarbyl group having 1 to 10 carbon atoms, or a hydrocarbyloxyhydrocarbyl group having 2 to 12 carbon atoms. More specifically, Q ¹ and Q ² may each be an alkyl group having 1 to 6 carbon atoms, or an alkyl group having 1 to 6 carbon atoms substituted with an alkoxy having 1 to 6 carbon atoms. For example, Q ¹ and Q ² may each independently be hydrogen, methyl, ethyl, or tert-butoxy substituted hexyl. More specifically, T ¹ may be silicon (Si), and both Q ¹ and Q ² may be methyl, or one of Q ¹ and Q ² may be methyl and the other may be tert-butoxy substituted hexyl.

Specifically, the metallocene compound represented by Formula 1 may be represented by any one of the following Formulas 1-1 to 1-4.

[Formula 1-1]

[Formula 1-2]

[Formula 1-3]

[Formula 1-4]

^In _Formulas ^{1-1 to 1-4 , M 1 ,}

And, in Formula 1, R ¹ to R ⁴ may each be hydrogen or a hydrocarbyl group having 1 to 10 carbon atoms, and R ⁵ and R ⁶ may each be a hydrocarbyl group having 1 to 10 carbon atoms. Specifically, R ¹ to R ⁴ may each be hydrogen or alkyl having 1 to 10 carbon atoms, and R ⁵ and R ⁶ may each be alkyl having 1 to 10 carbon atoms. More specifically, R ¹ to R ⁴ may each be hydrogen or methyl, and R ⁵ and R ⁶ may be methyl.

And, in Formula 1, M ¹ may be titanium (Ti), zirconium (Zr), or hafnium (Hf), and preferably titanium (Ti).

And, in Formula 1, X ^{1 and}

And, in Formula 1, the second metallocene compound may be represented by one of the following structural formulas.

Metallocene compounds represented by the above structural formulas can be synthesized by applying known reactions, and more detailed synthesis methods can be referred to the Examples and Synthesis Examples described later.

As described above, the transition metal compound represented by Formula 1 used in the present invention controls the degree of introduction of alpha-olefin monomers in the copolymerization process due to the structural characteristics of the catalyst and exhibits the density as described above, and as a result, excellent Flow stone and stretching processability can be secured.

In the present invention, the polymerization reaction can be performed by continuously polymerizing ethylene and alpha-olefin monomers by continuously introducing hydrogen in the presence of a catalyst composition containing one or more transition metal compounds represented by Formula 1, and specific This may be performed while introducing hydrogen at 5 to 100 cc/min.

The hydrogen gas suppresses the rapid reaction of the transition metal compound at the beginning of polymerization and serves to terminate the polymerization reaction. Accordingly, an ethylene/alpha-olefin copolymer with a narrow molecular weight distribution can be effectively produced by controlling the use and amount of hydrogen gas.

For example, the hydrogen may be introduced at 5 cc/min or more, or 7 cc/min or more, or 10 cc/min or more, or 15 cc/min or more, or 19 cc/min or more, and 100 cc/min or less, Alternatively, it may be administered at 50 cc/min or less, or 45 cc/min or less, or 35 cc/min or less, or 29 cc/min or less. When added under the above conditions, the produced ethylene/alpha-olefin copolymer can implement the above-mentioned physical properties.

If the content of hydrogen gas is added at less than 5 cc/min, the completion of the polymerization reaction may not occur uniformly, making it difficult to manufacture an ethylene/alpha-olefin copolymer with desired physical properties, and if the amount of hydrogen gas is added at a content exceeding 100 cc/min, the polymerization reaction may not be completed uniformly. In this case, there is a risk that the termination reaction may occur too quickly, resulting in the production of an ethylene/alpha-olefin copolymer with a very low molecular weight.

Additionally, the polymerization reaction can be performed at 100°C to 200°C, and by controlling the polymerization temperature along with the hydrogen input amount, the crystallinity distribution and molecular weight distribution in the ethylene/alpha-olefin copolymer can be more easily controlled. Specifically, the polymerization reaction may be performed at 100°C to 200°C, 120°C to 180°C, 130°C to 170°C, and 140°C to 160°C, but is not limited thereto.

In the present invention, a cocatalyst may be additionally used in the catalyst composition to activate the transition metal compound of Formula 1. The cocatalyst is an organometallic compound containing a Group 13 metal, and may specifically include one or more selected from the following Chemical Formulas 2 to 4.

[Formula 2]

R ₈ -[Al(R ₇ )-O] _n -R ₉

In Formula 2,

R ₇ , R ₈ and R ₉ are each independently hydrogen, halogen, C _1-20 hydrocarbyl group, or C _1-20 hydrocarbyl group substituted with halogen,

n is an integer greater than or equal to 2,

[Formula 3]

D( _R10 ) ₃

In Formula 3 above,

D is aluminum or boron,

R ₁₀ is each independently halogen, C _1-20 hydrocarbyl group, C _1-20 hydrocarbyloxy group, or C _1-20 hydrocarbyl group substituted with halogen,

[Formula 4]

[LH] ⁺ [W(A) ₄ ] ^- or [L] ⁺ [W(A) ₄ ] ^-

In Formula 4 above,

L is a neutral or cationic Lewis base,

H is a hydrogen atom,

W is a group 13 element,

A is each independently a C _1-20 hydrocarbyl group; C _1-20 hydrocarbyloxy group; and substituents in which one or more hydrogen atoms of these substituents are substituted with one or more substituents selected from halogen, C _1-20 hydrocarbyloxy group, and C _1-20 hydrocarbyl (oxy)silyl group.

Specifically, in Formula 4, [LH] ⁺ is Bronsted acid.

For example, [LH] ⁺ is trimethylammonium; triethylammonium; tripropylammonium; Tributylammonium; diethylammonium; trimethylphosphonium; or triphenylphosphonium, where [L] ⁺ is N,N-diethylanilinium; Or triphenylcarbonium.

Additionally, in Formula 4, W may be B ³⁺ or Al ³⁺ .

The compound represented by Formula 2 may serve as an alkylating agent and an activator, the compound represented by Formula 3 may serve as an alkylating agent, and the compound represented by Formula 4 may serve as an activator. there is.

More specifically, the compound of Formula 2 may be an alkylaluminoxane-based compound in which repeating units are bonded in a linear, circular, or network form. Specific examples include methylaluminoxane (MAO), ethyl aluminoxane, and isobutyl aluminoxane. Or tert-butyl aluminoxane, etc. may be mentioned. Non-limiting examples of the compound represented by Formula 2 above include methylaluminoxane, ethyl aluminoxane, isobutyl aluminoxane, or tert-butyl aluminoxane.

Non-limiting examples of the compound represented by Formula 3 include trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, tripropyl aluminum, tributyl aluminum, dimethyl chloroaluminum, triisopropyl aluminum, tri-sec-butyl aluminum, Tricyclopentyl aluminum, tripentyl aluminum, triisopentyl aluminum, trihexyl aluminum, trioctyl aluminum, ethyldimethyl aluminum, methyldiethyl aluminum, triphenyl aluminum, tri-p-tolyl aluminum, dimethyl aluminum methoxide or dimethyl aluminum. Toxide, etc. can be mentioned.

Lastly, non-limiting examples of the compound represented by Formula 4 include trimethylammonium tetrakis(pentafluorophenyl)borate, triethylammonium tetrakis(pentafluorophenyl)borate, and N,N-dimethylanilinium tetrakis( Pentafluorophenyl)borate, N,N-dimethylanilinium n-butyltris(pentafluorophenyl)borate, N,N-dimethylanilinium Benzyltris(pentafluorophenyl)borate, N,N-dimethylanilinium Tetrakis(4-(t-butyldimethylsilyl)-2,3,5,6-tetrafluorophenyl)borate, N,N-dimethylanilinium tetrakis(4-(triisopropylsilyl)-2,3 ,5,6-tetrafluorophenyl)borate, N,N-dimethylanilinium pentafluorophenoxytris(pentafluorophenyl)borate, N,N-dimethyl-2,4,6-trimethylanilinium tetrakis (pentafluorophenyl)borate, trimethylammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate, N,N-dimethylanilinium tetrakis(2,3,4,6-tetrafluorophenyl) )borate, hexadecyldimethylammonium tetrakis(pentafluorophenyl)borate, N-methyl-N-dodecylanilinium tetrakis(pentafluorophenyl)borate or methyldi(dodecyl)ammonium tetrakis(pentafluorophenyl)borate Phenyl) borate, etc. can be mentioned.

Among the above-mentioned compounds, the cocatalyst may be, more specifically, an alkylaluminoxane-based cocatalyst such as methylaluminoxane.

The amount of the cocatalyst used can be appropriately adjusted depending on the physical properties or effects of the desired hybrid supported metallocene catalyst.

The cocatalyst may be used in an appropriate amount to ensure sufficient activation of the transition metal compound of Formula 1. The amount of the cocatalyst used can be appropriately adjusted depending on the physical properties or effects of the desired hybrid supported metallocene catalyst.

In the present invention, the transition metal compound of Formula 1 may be used in the form supported on a carrier.

When the transition metal compound of Formula 1 is supported on a carrier, the weight ratio of the transition metal compound and the carrier may be 1:10 to 1:1000, more specifically 1:10 to 1:500. When a carrier and a transition metal compound are included in the neutral ratio within the above-mentioned range, an optimal shape can be obtained. In addition, when the co-catalyst is supported on a carrier, the weight ratio of co-catalyst to carrier may be 1:1 to 1:100, more specifically 1:1 to 1:50. When the cocatalyst and carrier are included in the above weight ratio, the catalytic activity can be improved and the microstructure of the produced polymer can be optimized.

Meanwhile, the carrier may be silica, alumina, magnesia, or a mixture thereof, or these materials may be dried at high temperature to remove moisture from the surface, thereby forming a state containing highly reactive hydroxy groups or siloxane groups on the surface. It may also be used. In addition, the high-temperature dried carriers may further contain oxides, carbonates, sulfates, or nitrates such as Na ₂ O, K ₂ CO ₃ , BaSO ₄ and Mg(NO ₃ ) ₂ .

The drying temperature of the carrier is preferably 200°C to 800°C, more preferably 300°C to 600°C, and most preferably 300°C to 400°C. If the drying temperature of the carrier is less than 200 ℃, there is too much moisture, so the moisture on the surface reacts with the cocatalyst. If it is more than 800 ℃, the pores on the surface of the carrier merge, the surface area decreases, and many hydroxyl groups on the surface disappear. This is undesirable because only siloxane residues remain and the number of reaction sites with the cocatalyst decreases.

In addition, the amount of hydroxyl groups on the surface of the carrier is preferably 0.1 mmol/g to 10 mmol/g, and more preferably 0.5 mmol/g to 5 mmol/g. The amount of hydroxy groups on the surface of the carrier can be adjusted by the preparation method and conditions of the carrier or drying conditions such as temperature, time, vacuum or spray drying.

In addition, during the polymerization reaction, an organoaluminum compound is further added to remove moisture in the reactor, and the polymerization reaction can proceed in its presence. Specific examples of such organic aluminum compounds include trialkylaluminum, dialkyl aluminum halide, alkyl aluminum dihalide, aluminum dialkyl hydride, or alkyl aluminum sesqui halide, and more specific examples thereof include Al(C ₂ H ₅ ) ₃ , Al(C ₂ H ₅ ) ₂ H, Al(C ₃ H ₇ ) ₃ , Al(C ₃ H ₇ ) ₂ H, Al(iC ₄ H ₉ ) ₂ H, Al(C ₈ H ₁₇ ) ₃ , Al(C ₁₂ H ₂₅ ) ₃ , Al(C ₂ H ₅ )(C ₁₂ H ₂₅ ) ₂ , Al(iC ₄ H ₉ )(C ₁₂ H ₂₅ ) ₂ , Al(iC ₄ H ₉ ) ₂ H, Al(iC ₄ H ₉ ) ₃ , (C ₂ H ₅ ) ₂ AlCl, (iC ₃ H ₉ ) ₂ AlCl, or (C ₂ H ₅ ) ₃ A _l2 Cl ₃ . These organoaluminum compounds may be continuously added to the reactor, and may be added at a rate of about 0.1 to 10 moles per 1 kg of the reaction medium added to the reactor for appropriate moisture removal.

In addition, the polymerization pressure is about 1 Kgf/cm ² to about 100 Kgf/cm ² , preferably about 1 Kgf/cm ² to about 50 Kgf/cm ² , and more preferably about 5 Kgf/cm ² to about 30 Kgf. It can be / ^cm2 .

In addition, when the transition metal compound is used in the form supported on a carrier, the transition metal compound may be used in an aliphatic hydrocarbon solvent having 5 to 12 carbon atoms, such as pentane, hexane, heptane, nonane, decane, and isomers thereof, toluene, and benzene. It can be dissolved in an aromatic hydrocarbon solvent such as dichloromethane, a hydrocarbon solvent substituted with a chlorine atom such as chlorobenzene, or added after dilution. The solvent used here is preferably treated with a small amount of alkyl aluminum to remove a small amount of water or air, which acts as a catalyst poison, and it is also possible to use an additional cocatalyst.

In this way, the first ethylene-alpha-olefin copolymer (a) can be produced by copolymerizing ethylene and alpha-olefin using the metallocene catalyst described above.

By the above-described production method, (a) the first ethylene-alpha olefin copolymer having the above-described physical properties can be produced.

(b) second ethylene-alphaolefin copolymer

Meanwhile, the polyethylene composition according to one embodiment of the invention provides mechanical properties through blending of (a) the first ethylene-alpha olefin copolymer and (b) the second ethylene-alpha olefin copolymer, which has excellent mechanical properties. By adjusting the balance between physical properties and stretchability properties, it is possible to maintain mechanical properties, productivity and stretching stability equivalent to or superior to existing ones, and provide characteristics suitable for manufacturing biaxially stretched films with high shrinkage resistance, excellent printability and transparency.

Specifically, the (b) second ethylene-alpha olefin copolymer has a density of 0.930 g/cm ³ to 0.960 g/cm ³ and a melt index (MI _2.16 , 190 ^o C, 2.16 kg load) of 0.2 g/cm 3 It may be 10 min to 2.0 g/10 min.

Preferably, the second ethylene-alphaolefin copolymer (b) has a density of 0.935 g/cm ³ or more, or 0.938 g/cm ³ or more, or 0.940 g/cm ³ or more, and 0.955 g/cm ³ It may be less than or equal to 0.950 g/cm ³ or less than or equal to 0.945 g/cm ³ .

In addition, the second ethylene-alphaolefin copolymer (b) has a melt index (MI _2.16 , 190 ^o C, 2.16 kg load) of 0.2 g/10min or more, or 0.3 g/10min or more, or 0.4 g/10min. or more, but may be less than or equal to 1.8 g/10min, or less than or equal to 1.5 g/10min, or less than or equal to 1.2 g/10min.

And, the (b) second ethylene-alpha olefin copolymer has a number average molecular weight Mn of 20,000 g/mol or more or 20,000 g/mol or more to 35,000 g/mol or less, and a weight average molecular weight Mw of 95,000 g/mol or more. to 150000 g/mol or less, and the molecular weight distribution Mw/Mn may be 3.5 to 4.8.

Preferably, the number average molecular weight Mn of the second ethylene-alphaolefin copolymer (b) may be 22000 g/mol or more, or 23000 g/mol or more, or 25000 g/mol or more, and may be 33000 g/mol or less. , or 32000 g/mol or less, or 30000 g/mol or less.

In addition, the weight average molecular weight Mw of the second ethylene-alpha olefin copolymer (b) may be 100,000 g/mol or more, or 105,000 g/mol or more, or 110,000 g/mol or more, and may be 140,000 g/mol or less, or It may be less than or equal to 130000 g/mol, or less than or equal to 120000 g/mol.

In addition, the molecular weight distribution Mw/Mn of the second ethylene-alphaolefin copolymer (b) is 3.6 or more, or 3.7 or more, or 3.9 or more, or 4.0 or more, and is 4.7 or less, or 4.5 or less, or 4.3 or less, or 4.2. It may be below.

The (b) second ethylene-alpha olefin copolymer may have at least one of the above-described physical properties, and may have all of the above-described physical properties in order to exhibit excellent mechanical strength.

Here, the method for measuring each physical property of the second ethylene-alpha olefin copolymer (b) is the same as previously described for the polyethylene composition, and detailed description is omitted.

Meanwhile, the second ethylene-alphaolefin copolymer (b) includes ethylene and 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1- and one or more alpha-olefins selected from the group consisting of dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene, and mixtures thereof.

Additionally, the second ethylene-alpha olefin copolymer (b) may be an ethylene/1-hexene copolymer.

When the (b) second ethylene-alpha olefin copolymer is the above-mentioned copolymer, the above-mentioned physical properties can be more easily realized. However, the types of the second ethylene-alpha olefin copolymer (b) are not limited to the above-mentioned types, and various types known in the technical field to which the present invention pertains may be provided as long as they can exhibit the above-mentioned physical properties.

And, the second ethylene-alpha olefin copolymer (b) was manufactured in the presence of a metallocene catalyst.

Specifically, the (b) second ethylene-alphaolefin copolymer is a first metallocene compound represented by the following formula (6) and a second metallocene compound represented by the following formula (7) in a ratio of 1:2 to 1:8. It can be prepared by copolymerizing ethylene and a comonomer while adding hydrogen gas in the presence of a catalyst composition containing a molar ratio of .

[Formula 6]

(Cp ¹ R ^a ) _m (Cp ² R ^b )M ² Z ² _3-m

In Formula 6 above,

M ² is a Group 4 transition metal;

Cp ¹ and Cp ² are each cyclopentadienyl, which is unsubstituted or substituted with C _1-20 hydrocarbon;

R ^a and R ^b are the same or different from each other, and are each independently hydrogen, C _1-20 alkyl, C _1-20 alkoxy, C _2-20 alkoxyalkyl, C _6-20 aryl, C _6-20 aryloxy, C _2-20 alkenyl, C _7-40 alkylaryl, C _7-40 arylalkyl, C _8-40 arylalkenyl, C _2-20 alkynyl, or selected from the group consisting of N, O and S substituted or unsubstituted C _2-20 heteroaryl containing one or more heteroatoms, provided that at least one of R ^a and R ^b is not hydrogen;

Z ² is each independently halogen, C _1-20 alkyl, C _2-20 alkenyl, C _7-40 alkylaryl, C _7-40 arylalkyl, C _6-20 aryl, substituted or unsubstituted C _1-20 alkylidene, substituted or unsubstituted amino group, C _2-20 alkylalkoxy, or C _7-40 arylalkoxy;

m is 1 or 0;

[Formula 7]

In Formula 7 above,

M ³ is a group 4 transition metal,

T ² is carbon, silicon or germanium,

X ³ and X ⁴ are the same or different from each other and are each independently halogen or C _1-20 alkyl,

R ¹¹ to R ¹⁴ are the same or different from each other, and are each independently hydrogen, C _1-20 alkyl, C _2-20 alkenyl, C _6-20 aryl, C _7-20 alkylaryl, C _{7- 20} arylalkyl, or R ¹¹ to R ¹⁴ two or more of which are adjacent to each other are connected to each other to form a substituted or unsubstituted aliphatic ring, an aromatic ring, or a heteroaromatic ring containing at least one selected from the group consisting of N, O, and S,

Q ³ and Q ⁴ are the same or different from each other, and are each independently C _1-20 alkyl, C _2-20 alkenyl, C _6-30 aryl, or C _2-20 alkoxy alkyl,

R ¹⁵ is C _1-20 alkyl, C _2-20 alkenyl, or C _6-30 aryl.

Meanwhile, in this specification, unless there is a special limitation, the following terms may be defined as follows.

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

The C _1-20 alkyl group may be a straight-chain, branched-chain, or cyclic alkyl group. Specifically, the C _1-20 alkyl group is a C _1-15 straight chain alkyl group; C _1-10 straight chain alkyl group; C _1-5 straight chain alkyl group; C _3-20 branched chain or cyclic alkyl group; C _3-15 branched chain or cyclic alkyl group; Or it may be a C _3-10 branched chain or cyclic alkyl group. More specifically, the alkyl group of C _1-20 is methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, tert-butyl group, n-pentyl group, iso-pentyl group, It may be a neo-pentyl group or a cyclohexyl group.

The C _2-20 alkenyl group may be a straight chain, branched chain, or cyclic alkenyl group. Specifically, the C _2-20 alkenyl group is C _2-20 straight chain alkenyl group, C _2-10 straight chain alkenyl group, C _2-5 straight chain alkenyl group, C _3-20 branched chain alkenyl group, C _3-15 branched chain alkenyl group. It may be a nyl group, a C _3-10 branched chain alkenyl group, a C _5-20 cyclic alkenyl group, or a C _5-10 cyclic alkenyl group. More specifically, the C _2-20 alkenyl group may be an ethenyl group, propenyl group, butenyl group, pentenyl group, or cyclohexenyl group.

C _6-20 Aryl refers to a monocyclic, bicyclic or tricyclic aromatic hydrocarbon and includes monocyclic or condensed ring aryl. Specifically, C _6-20 aryl may be a phenyl group, biphenyl group, naphthyl group, anthracenyl group, phenanthrenyl group, or fluorenyl group.

C _7-40 alkylaryl may refer to a substituent in which one or more hydrogens of aryl are replaced by alkyl. Specifically, C _7-40 alkylaryl may be methylphenyl, ethylphenyl, n-propylphenyl, iso-propylphenyl, n-butylphenyl, iso-butylphenyl, tert-butylphenyl, or cyclohexylphenyl.

C _7-40 Arylalkyl may refer to a substituent in which one or more hydrogens of alkyl are replaced by aryl. Specifically, C _7-40 arylalkyl may be a benzyl group, phenylpropyl, or phenylhexyl.

Examples of C _6-20 aryloxy include phenoxy, biphenoxy, naphthoxy, etc., but are not limited thereto.

The C _1-20 alkoxy group includes methoxy group, ethoxy group, phenyloxy group, cyclohexyloxy group, etc., but is not limited thereto.

The C _2-20 alkoxyalkyl group is a functional group in which one or more hydrogens of the alkyl group described above are replaced with an alkoxy group, and specifically, methoxymethyl group, methoxyethyl group, ethoxymethyl group, iso-propoxymethyl group, and iso-propoxy group. Alkoxyalkyl groups such as ethyl group, iso-propoxyhexyl group, tert-butoxymethyl group, tert-butoxyethyl group, and tert-butoxyhexyl group may be included, but are not limited thereto.

The C _1-20 alkylsilyl group or C _1-20 alkoxysilyl group is a functional group in which 1 to 3 hydrogens of -SiH ₃ are replaced with 1 to 3 alkyl groups or alkoxy groups as described above, specifically methylsilyl group, die Alkylsilyl groups such as methylsilyl group, trimethylsilyl group, dimethylethylsilyl group, diethylmethylsilyl group, or dimethylpropylsilyl group; Alkoxysilyl groups such as methoxysilyl group, dimethoxysilyl group, trimethoxysilyl group, or dimethoxyethoxysilyl group; Alkoxyalkylsilyl groups such as methoxydimethylsilyl group, diethoxymethylsilyl group, or dimethoxypropylsilyl group may be included, but are not limited thereto.

The C _1-20 silylalkyl group is a functional group in which one or more hydrogens of the alkyl group described above are replaced with a silyl group, and specifically includes -CH ₂ -SiH ₃ , methylsilylmethyl group, or dimethylethoxysilylpropyl group. , but is not limited to this.

The sulfonate group has the structure of -O-SO ₂ -R', where R' may be a C _1-20 alkyl group. Specifically, the C _1-20 sulfonate group may include a methane sulfonate group or a phenyl sulfonate group, but is not limited thereto.

The heteroaryl is a C _2-20 heteroaryl containing at least one of N, O, and S as a heteroelement, and includes monocyclic or condensed ring heteroaryl. Specific examples include xanthene, thioxanthen, thiophene group, furan group, pyrrole group, imidazole group, thiazole group, oxazole group, oxadiazole group, triazole group, pyridyl group, bipyridyl group, and pyridyl group. Midyl group, triazine group, acridyl group, pyridazine group, pyrazinyl group, quinolinyl group, quinazoline group, quinoxalinyl group, phthalazinyl group, pyrido pyrimidinyl group, pyrido pyrazinyl group, pyrazino pyrazinyl group Ginyl group, isoquinoline group, indole group, carbazole group, benzoxazole group, benzoimidazole group, benzothiazole group, benzocarbazole group, benzothiophene group, dibenzothiophene group, benzofuranyl group, phenanthroline group ), isoxazolyl group, thiadiazolyl group, phenothiazinyl group, and dibenzofuranyl group, etc., but is not limited to these.

And, the Group 4 transition metal may be titanium (Ti), zirconium (Zr), hafnium (Hf), or rutherphodium (Rf), and specifically, titanium (Ti), zirconium (Zr), or hafnium (Hf). It may be, and more specifically, it may be zirconium (Zr) or hafnium (Hf), but it is not limited thereto.

Additionally, the Group 13 element may be boron (B), aluminum (Al), gallium (Ga), indium (In), or thallium (Tl), and may specifically be boron (B) or aluminum (Al). and is not limited to this.

The above-mentioned substituents are optionally hydroxy groups within the range of achieving the same or similar effects as the desired effect; halogen; Alkyl group or alkenyl group, aryl group, alkoxy group; an alkyl group or alkenyl group, an aryl group, or an alkoxy group containing one or more heteroatoms from groups 14 to 16; silyl group; Alkylsilyl group or alkoxysilyl group; Phosphine group; phosphide group; Sulfonate group; and may be substituted with one or more substituents selected from the group consisting of a sulfone group.

In addition, the fact that two adjacent substituents are connected to each other to form an aliphatic or aromatic ring means that the atom(s) of the two substituents and the atoms (atoms) to which the two substituents are bonded are connected to each other to form a ring. . Specifically, examples in which R ₉ and R ₁₀ of -NR ₉ R ₁₀ are connected to each other to form an aliphatic ring include a piperidinyl group, and R ₉ and R ₁₀ of -NR ₉ R ₁₀ are Examples of groups connected to each other to form aromatic rings include pyrrolyl groups.

In the catalyst composition, the first metallocene compound represented by Chemical Formula 6 is a non-crosslinked compound containing ligands of Cp ¹ and Cp ² , and is mainly a low molecular weight copolymer with a low SCB (short chain branch) content. It is advantageous for making

Specifically, in Formula 6, the ligands of Cp ¹ and Cp ² may be the same or different from each other, are each cyclopentadienyl, and may be substituted with 1 or more or 1 to 3 C _1-10 alkyl. In this way, the ligands of Cp ¹ and Cp ² can exhibit high polymerization activity by having a lone pair of electrons that can act as a Lewis base. In particular, the ligands of Cp ¹ and Cp ² are cyclopentadienyl groups with relatively little steric hindrance. Therefore, it exhibits high polymerization activity and low hydrogen reactivity, allowing low molecular weight polyethylene to be polymerized with high activity.

In addition, the ligands of Cp ¹ and Cp ² , for example, have properties such as chemical structure, molecular weight, molecular weight distribution, mechanical properties, and transparency of polyethylene, which is manufactured by controlling the degree of steric hindrance effect depending on the type of substituted functional group. can be easily adjusted. Specifically, the ligands of Cp ¹ and Cp ² are each substituted with R ^a and R ^b , where R ^a and R ^b are the same or different from each other, and are each independently hydrogen, C _1-20 alkyl, C It may be _2-20 alkoxyalkyl, C _7-40 arylalkyl, or substituted or unsubstituted C _2-12 heteroaryl containing one or more heteroatoms selected from the group consisting of N, O and S, and more Specifically, C _1-10 alkyl, C _2-10 alkoxyalkyl, C _7-20 arylalkyl, or substituted or unsubstituted C containing one or more heteroatoms selected from the group consisting of N, O and S. _4-12 heteroaryl;

In addition, M ² Z ² _3-m exists between the ligands of Cp ¹ and Cp ² , and M ² Z ² _3-m may affect the storage stability of the metal complex. In order to more effectively ensure this effect, Z ¹ may each independently be halogen or C _1-20 alkyl, and more specifically, may each independently be F, Cl, Br or I. In addition, M ² is Ti, Zr, or Hf; is Zr or Hf; Or it may be Zr.

Among the first metallocene compounds, in Formula 6, Cp ¹ and Cp ² are each unsubstituted or substituted cyclopentadienyl group, and R ^a and R ^b are each independently hydrogen, C _1-10 alkyl, C _2-10 alkoxyalkyl, or C _7-20 arylalkyl, where at least one of R ^a and R ^b is alkoxyalkyl such as t-butoxyhexyl group, more specifically, -(CH ₂ ) _p -OR It may be a compound that is a substituent of ^c (where R ^c is a straight or branched chain alkyl group having 1 to 6 carbon atoms, and p is an integer of 2 to 4.). In this case, when producing polyethylene using a comonomer, it exhibits a low conversion rate for comonomers compared to other Cp-based catalysts that do not contain the above substituent, so that low molecular weight polyethylene with controlled copolymerization or comonomer distribution can be produced. In addition, when the first metallocene compound with the above structure is supported on a carrier, the -(CH ₂ ) _p -OR ^c group among the substituents forms a covalent bond through close interaction with the silanol group on the surface of the silica used as the carrier. It can be formed and stable supported polymerization is possible.

The first metallocene compound represented by Formula 6 may be, for example, a compound represented by one of the following structural formulas, but is not limited thereto.

The first metallocene compound represented by Chemical Formula 6 can be synthesized by applying known reactions, and the Examples can be referred to for more detailed synthesis methods.

Meanwhile, in one embodiment of the invention, the second metallocene compound represented by Formula 7 includes an aromatic ring compound including cyclopentadienyl or a derivative thereof and a nitrogen atom, and the aromatic ring compound and the nitrogen atom It has a structure in which the atoms are cross-linked by a bridging group, T ² Q ³ Q ⁴ . The second metallocene compound having this specific structure can be applied to the polymerization reaction of polyethylene, exhibits high activity and copolymerization, and can provide a high molecular weight olefin copolymer.

In particular, the second metallocene compound represented by Chemical Formula 7 has a well-known CGC (constrained geometry catalyst) structure, so it is excellent in introducing comonomers, and in addition, it has a comonomer structure due to the electronic and steric properties of the ligand. The distribution of monomers is controlled. From these properties, the average ethylene sequence length (ASL) is adjusted to increase the middle to high molecular region in the molecular weight distribution, thereby expanding the ratio of tie molecule fraction and increasing the entanglement of the polymer chain, along with excellent mechanical properties. It is easy to manufacture polyethylene resin that exhibits long-term stability and processability.

M ³ of the metallocene compound represented by Formula 7 may be a Group 4 transition metal, preferably titanium (Ti), zirconium (Zr), or hafnium (Hf).

Preferably, in Formula 7, T ² may be silicon.

Preferably, in Formula 7, X ³ and X ⁴ may each independently be methyl or chlorine (Cl).

Preferably, in Formula 7, R ¹¹ to R ¹⁴ are the same or different and may each independently be methyl or phenyl.

Preferably, in Formula 7, two or more of R ¹¹ to R ¹⁴ adjacent to each other are connected to each other to form a substituted or unsubstituted aliphatic ring, an aromatic ring, or any one selected from the group consisting of N, O, and S. A heteroaromatic ring containing the above can be formed. For example, in Formula 7, R ¹¹ to R ¹⁴ Among them, two or more adjacent ones are connected to each other to form an aliphatic ring, aromatic ring, or heteroaromatic ring, and cyclopentadiene is fused to an indenyl group, fluorenyl group, benzothiophene group, or dibenzo It can form thiophene groups (dibenzothiophene), etc. Additionally, the indenyl group, fluorenyl group, benzothiophene group, and dibenzothiophene group may be substituted with one or more substituents.

Preferably, in Formula 7, R ¹⁵ to R ¹⁶ are the same or different, and may each independently be methyl, ethyl, phenyl, propyl, hexyl, or tert-butoxyhexyl.

Preferably, in Formula 7, R ¹⁷ may be methyl, ethyl, n-propyl, iso-propyl, n-butyl, or tert-butyl.

As a second metallocene compound that can provide a polyethylene resin with excellent long-term stability and processability along with excellent mechanical properties through an increased middle molecular region, the metallocene compound of Formula 7 is a group consisting of the following compounds It may be any one selected from, but the present invention is not limited thereto:

.

The second metallocene compound represented by Chemical Formula 7 can be synthesized by applying known reactions. Specifically, it may be manufactured by connecting a nitrogen compound and a cyclopentadiene derivative with a bridge compound to prepare a ligand compound, and then performing metallation by adding a metal precursor compound, but is not limited to this and is described in more detail. For synthetic methods, refer to the examples.

The second metallocene compound of Formula 7 has excellent activity and can polymerize high molecular weight polyethylene resin. In particular, it exhibits high polymerization activity even when used while supported on a carrier, making it possible to produce ultra-high molecular weight polyethylene resin.

In addition, even when a polymerization reaction is carried out including hydrogen to produce a polyethylene resin having a high molecular weight and a wide molecular weight distribution, the second metallocene compound of Chemical Formula 7 according to the present invention exhibits low hydrogen reactivity and still has a high molecular weight distribution. Due to its activity, polymerization of ultra-high molecular weight polyethylene resin is possible. Therefore, even when used in combination with a catalyst having other characteristics, it is possible to produce a polyethylene resin that satisfies the high molecular weight characteristics without a decrease in activity, making it easy to produce polyethylene resins that include high molecular weight polyethylene resins and have a wide molecular weight distribution. It can be manufactured.

As described above, in the catalyst composition, the first metallocene compound represented by Formula 6 mainly contributes to making a low molecular weight copolymer with a low SCB content, and the second metallocene compound represented by Formula 7 The compounds can mainly contribute to making high molecular weight copolymers with high SCB content. More specifically, the catalyst composition exhibits high copolymerizability to comonomers in the copolymer in the high molecular weight region due to the second metallocene compound, and also exhibits high copolymerization in the low molecular weight region due to the first metallocene compound. shows low copolymerization of the comonomer. As a result, a polyethylene resin that not only has excellent mechanical properties but also exhibits a bimodal molecular weight distribution and excellent heat resistance can be manufactured.

In particular, the above-described physical properties can be achieved by controlling the content ratio of the first and second metallocene compounds in the catalyst composition in the present invention, and the resulting improvement effect can be further enhanced. Specifically, by including the second metallocene compound in a higher content than the first metallocene compound in the catalyst composition, the middle molecular region within the molecule is increased to expand the tie molecule fraction ratio and the polymer chain. Entanglement can be increased and the ratio of the high molecule region to the low molecule region can be optimized.

Specifically, the first and second metallocene compounds should be included in a molar ratio of 1:2 to 1:8. Preferably, the first and second metallocene compounds may be included in a molar ratio of 1:3 to 1:7, 1:4 to 1:6, or 1:4.5 to 1:5.5. When the first metallocene compound and the second metallocene compound are in the above molar ratio, the polyethylene resin manufactured using them adjusts the balance between mechanical properties and elongation, thereby providing mechanical properties and productivity equivalent to or superior to the existing ones. and stretching stability, and can improve both high shrinkage resistance, printability, and transparency.

Meanwhile, the first and second metallocene compounds have the above-described structural characteristics and can be stably supported on a carrier.

In this case, the first and second metallocene compounds are used while supported on the carrier. When used as a supported catalyst, the particle shape and bulk density of the produced polymer are excellent, and can be suitably used in conventional slurry polymerization, bulk polymerization, and gas phase polymerization processes.

Specific examples of the carrier include silica, alumina, magnesia, silica-alumina, silica-magnesia, etc., and these are usually oxides such as Na ₂ O, K ₂ CO ₃ , BaSO ₄ , and Mg(NO ₃ ) ₂ , may further include carbonate, sulfate, and nitrate components. Among these, when using a silica carrier, the transition metal compound is supported by chemically bonding with reactive functional groups such as siloxane groups present on the surface of the silica carrier, so there is almost no catalyst released from the surface of the carrier during the polymer polymerization process. As a result, when producing polymers through slurry or vapor phase polymerization, fouling that occurs on the reactor wall or between polymer particles can be minimized.

Additionally, the carrier may be surface modified through a calcination or drying process to increase support efficiency and minimize leaching and fouling. Through the above surface modification step, moisture on the surface of the carrier that inhibits reaction with the supporting components is removed, and instead, the content of reactive functional groups capable of chemical bonding with the supporting components, such as hydroxy groups and siloxane groups, is increased. You can.

Specifically, the calcination or drying process for the carrier may be performed in a range from a temperature at which moisture disappears from the surface of the carrier to a temperature below which reactive functional groups, especially hydroxy groups (OH groups) present on the surface are completely eliminated. Specifically, the temperature may be 150°C to 600°C, or 200°C to 500°C. If the temperature during calcination or drying of the carrier is low below 150°C, the moisture removal efficiency is low, and as a result, there is a risk that the moisture remaining in the carrier may react with the cocatalyst and reduce the supporting efficiency. On the other hand, if the drying or calcining temperature is too high, exceeding 600 ℃, the specific surface area decreases as the pores existing on the surface of the carrier merge, and many reactive functional groups such as hydroxy groups or silanol groups existing on the surface are lost, and siloxane There is a risk that only residues will remain and the number of reaction sites with the cocatalyst will decrease.

When the first and second metallocene compounds described above are supported on a carrier, for example, when the carrier is silica, the total amount of the first and second metallocene compounds is 40 μmol or more, or 80 μmol based on 1 g of silica. or more, and may be supported in a content range of 240 μmol or less, or 160 μmol or less. When supported in the above content range, it exhibits appropriate supported catalyst activity, which can be advantageous in terms of maintaining the activity of the catalyst and economic efficiency.

In addition, the catalyst composition may additionally include a cocatalyst to improve high activity and process stability.

In the hybrid supported metallocene catalyst of the present invention, the type and content of the additional cocatalyst are as described above, and detailed details are omitted.

For example, among the above-mentioned compounds, the cocatalyst may be, more specifically, an alkylaluminoxane-based cocatalyst such as methylaluminoxane.

In addition, the alkylaluminoxane-based cocatalyst stabilizes the metallocene compounds and acts as a Lewis acid, and the functional group introduced into the bridge group of the second metallocene compound is a Lewis acid- Catalytic activity can be further improved by including a metal element that can form a bond through base interaction.

Additionally, the amount of the cocatalyst used can be appropriately adjusted depending on the physical properties or effects of the desired catalyst and resin composition. For example, when silica is used as the carrier, the cocatalyst may be supported in an amount of 8 mmol or more, or 10 mmol or more, and 25 mmol or less, or 20 mmol or less per weight of the carrier, for example, based on 1 g of silica. there is.

In addition, the above-described catalyst composition may be used for polymerization as such, or may be used in a prepolymerized state through contact with an ethylene monomer before use in a polymerization reaction. In this case, the production method according to one embodiment of the invention may further include the step of pre-polymerizing (or pre-polymerizing) the catalyst composition by contacting it with an ethylene monomer before producing polyethylene through a polymerization reaction.

In addition, the catalyst composition includes aliphatic hydrocarbon solvents having 5 to 12 carbon atoms, such as pentane, hexane, heptane, nonane, decane, and isomers thereof, aromatic hydrocarbon solvents such as toluene and benzene, and chlorine such as dichloromethane and chlorobenzene. It can be dissolved or diluted in an atom-substituted hydrocarbon solvent or the like and then introduced into the polymerization reaction described later. The solvent used here is preferably treated with a small amount of alkyl aluminum to remove a small amount of water or air, which acts as a catalyst poison, and it is also possible to use a cocatalyst.

Meanwhile, the polymerization process can be performed by contacting ethylene and a comonomer in the presence of the catalyst composition described above. In particular, the polymerization reaction may be bimodal, using two or more reactors, or may be performed in a single polymerization reactor.

And, the polymerization temperature may be 25°C to 500°C, preferably 25°C to 200°C, and more preferably 50°C to 150°C. Additionally, the polymerization pressure may be 1 kgf/cm2 to 100 kgf/cm2, preferably 1 kgf/cm2 to 50 kgf/cm2, and more preferably 5 kgf/cm2 to 30 kgf/cm2.

In addition, when 1-hexene is added as a comonomer in the copolymerization process, the amount of 1-hexene added may be about 4.0% by weight to about 6.0% by weight based on the total weight of ethylene added. More specifically, the amount of 1-hexene added is about 4.1% by weight or more, or about 4.2% by weight or more, or about 4.3% by weight or more, or about 4.4% by weight or more, or about 4.5% by weight or more, based on the total weight of ethylene input. , may be less than or equal to about 5.9 weight percent, or less than or equal to about 5.8 weight percent, or less than or equal to about 5.6 weight percent, or less than or equal to about 5.4 weight percent, or less than or equal to about 5.2 weight percent, or less than or equal to about 5.0 weight percent.

Meanwhile, the polyethylene resin according to the present invention can be produced by copolymerizing ethylene and a comonomer by adding hydrogen gas in the presence of the catalyst composition described above.

For example, the hydrogen gas has a content of 35 ppm to 250 ppm, or 40 ppm to 200 ppm, or 50 ppm to 190 ppm, or 55 ppm to 180 ppm, or 58 ppm to 170 ppm, or 60 ppm, based on the weight of ethylene. The content may be from ppm to 145 ppm.

In the step of supporting the catalyst precursor on the cocatalyst-supporting carrier, the first and second transition metal compounds are added to the cocatalyst-supporting carrier, stirred, and then a cocatalyst can be further added to prepare a supported catalyst.

In the hybrid supported metallocene catalyst according to the above embodiment, the content of the carrier, co-catalyst, co-catalyst supporting carrier, and transition metal compound used can be appropriately adjusted depending on the physical properties or effects of the desired supported catalyst.

On the other hand, if the molar ratio of the first transition metal compound and the second transition metal compound (first transition metal compound: second transition metal compound) is less than 1:0.3, there is a disadvantage in that it is difficult to produce ultra-low density polyethylene as copolymerization decreases. , if it exceeds 1:3.5, there is a problem in that it is difficult to reproduce the desired molecular structure of the polymer.

At this time, the amount of the metallocene compound supported on the silica carrier through the above step may be 0.01 to 1 mmol/g based on 1 g of the carrier. That is, it is preferable to control the amount to fall within the above-mentioned range, taking into account the contribution effect of the metallocene compound as a catalyst.

When preparing the hybrid supported catalyst, reaction solvents include hydrocarbon solvents such as pentane, hexane, and heptane; Alternatively, an aromatic solvent such as benzene, toluene, etc. may be used.

For detailed manufacturing methods of the supported catalyst, refer to the examples described below. However, the method for producing the supported catalyst is not limited to the content described herein, and the production method may additionally employ steps commonly employed in the technical field to which the present invention pertains, and the steps of the production method ( s) can be changed by conventionally changeable step(s).

Meanwhile, the polyethylene copolymer as described above can be prepared through a method comprising copolymerizing ethylene and alpha-olefin in the presence of the hybrid supported metallocene catalyst.

The above-described hybrid supported catalyst can exhibit excellent supporting performance, catalytic activity, and high copolymerization properties, and can produce a polyethylene copolymer capable of producing a biaxially stretched film with excellent expandable processing area characteristics and mechanical properties.

The method (b) for producing the second ethylene-alpha olefin copolymer may be performed by slurry polymerization using ethylene and alpha-olefin as raw materials in the presence of the above-described hybrid supported catalyst by applying conventional equipment and contact technology.

The method (b) for producing the second ethylene-alpha olefin copolymer may copolymerize ethylene and alpha-olefin using a continuous slurry polymerization reactor, a loop slurry reactor, etc., but is not limited thereto.

That is, in the case of the hybrid supported metallocene catalyst of the present invention in which the first metallocene compound and the second metallocene compound are supported at the molar ratio, the mechanical properties of the polyethylene copolymer are increased due to the interaction of two or more catalysts. In addition to physical properties, both processability and shrinkage can be further improved.

In the hybrid supported metallocene catalyst of the present invention, the polymerization process with a carrier for supporting the first metallocene compound and the second metallocene compound and an additional cocatalyst is performed by (a) the first ethylene-alpha The same as described above with respect to the olefin copolymer, and detailed information is omitted.

In this way, (b) the second ethylene-alpha olefin copolymer according to the present invention can be produced by copolymerizing ethylene and alpha-olefin using the above-described supported metallocene catalyst.

By the above-mentioned production method, (b) the second ethylene-alphaolefin copolymer having the above-mentioned physical properties can be produced.

biaxially stretched film

The polyethylene composition of one embodiment having the above physical properties maintains excellent mechanical properties, productivity, and stretching stability, and can stably form a biaxially stretched film with high shrinkage resistance, printability, and transparency.

Meanwhile, the biaxially stretched film can be manufactured by a conventional film manufacturing method except for using the polyethylene composition described above.

As an example, the polyethylene biaxially stretched film according to the present invention is a polyethylene composition sheet ( sheet) can be manufactured. Afterwards, using KARO 5.0 equipment, a polyethylene biaxially stretched film can be manufactured by performing biaxial stretching on a polyethylene composition sheet measuring 90 mm x 90 mm in width x height. The specific film manufacturing method and conditions are as described in Test Example 3 described later.

In addition, the polyethylene biaxially stretched film according to the present invention may further include additives well known in the field in addition to the polyethylene copolymer described above. Specifically, these additives include solvents, heat stabilizers, antioxidants, UV absorbers, light stabilizers, metal deactivators, fillers, reinforcing agents, plasticizers, lubricants, emulsifiers, pigments, optical bleaching agents, flame retardants, antistatic agents, foaming agents, etc. . The type of the additive is not particularly limited, and general additives known in the art can be used.

The polyethylene biaxially stretched film according to one embodiment of the present invention manufactured by the above-described method can improve performance with excellent expandability processing area characteristics and mechanical properties.

In particular, the polyethylene biaxially stretched film satisfies the MD draw ratio of 4 or more or 5 or more and the TD draw ratio of 6 or more or 8 or more.

The polyethylene biaxially stretched film may have a tensile strength of 80 MPa or more or 80 MPa to 150 MPa in the MD direction (MD / Machine Direction direction, film longitudinal direction, longitudinal direction) measured according to the ASTM D 882 standard, and in the TD direction The tensile strength (TD / Transverse Direction direction, film width direction, transverse direction) may be 110 MPa or more or 110 MPa to 250 MPa.

In addition, the polyethylene biaxially stretched film may have a tensile modulus in the MD direction of 700 MPa or more or 700 MPa to 1,500 MPa, as measured according to the ASTM D 882 standard, and a tensile modulus in the TD direction of 800 MPa or more or 800 MPa to 1,600 MPa. It may be MPa.

In addition, the polyethylene biaxially stretched film has a tensile elongation in the MD direction of 200% to 300%, as measured according to the ASTM D 882 standard. Alternatively, it may be 220% to 280%, and the tensile elongation in the TD direction is 70% to 140%. Or it may be 85% to 125%.

In addition, the polyethylene biaxially stretched film may have a tear strength in the MD direction of 6 N/mm to 14.8 N/mm, measured according to the ASTM 1922 standard, and a tensile strength in the TD direction of 2.5 N/mm to 6.8 N/mm. It can be mm.

In addition, the polyethylene biaxially stretched film may have a haze of 3% or less, or 3% or less to 0% or more, preferably 2.8% or less, or 2.5% or less, or 2.3%, as measured according to the ASTM 1003 standard. It may be 2.2% or less, 2.0% or less, or 1.9% or less, and considering the limitations in realizing the physical properties of the film, it may be 0.1% or more, 0.5% or more, 1.0% or more, 1.5% or more, or 1.6% or more. there is.

In addition, the polyethylene biaxially stretched film may have a gloss 45 ^o of 80 GU ^or more, or 80 GU to 100 GU, as measured according to the ASTM 2457 standard, and preferably 85 GU or more, or 88 GU or more. , or greater than or equal to 90 GU, or greater than or equal to 94 GU.

In addition, the above-mentioned polyethylene biaxially stretched film has excellent stretchability and stretching stability, so that the stretching ratio in the MD direction is more than 4 times, or 5 times, or more than 5 times, and in the TD direction, more than 6 times, or more than 7 times. It can be made into a stretched film. For example, the above-mentioned polyethylene biaxially stretched film has a total shrinkage rate in the MD/TD direction of 6.0% when contracted at 100°C for 7 minutes according to ASTM 1204 standards, under the condition that the stretching ratio exceeds 4 in the MD direction and the stretching ratio exceeds 6 in the TD direction. It may be 22.0% or less, or 21.5% or less, or 21% or less in the MD/TD direction total shrinkage when contracted at 120°C for 7 minutes according to ASTM 1204 standards.

The polyethylene biaxially stretched film may have a tensile strength in the MD direction of 100 MPa or more, 110 MPa or more, or 120 MPa or more, and may be 150 MPa or less, as measured according to the ASTM D 882 standard, and a tensile strength in the TD direction of 180 MPa or more. , 190 MPa or more, or 200 MPa or more and 250 MPa or less.

Accordingly, the average of the MD tensile strength and TD tensile strength of the biaxially stretched film measured according to ASTM D 882 may be 130 MPa or more, preferably 140 MPa or more, 150 MPa or more, or 160 MPa or more and 200 MPa or less. You can.

In addition, the polyethylene biaxially stretched film may have a tensile modulus in the MD direction of 600 MPa or more, or 645 MPa or more, and 1000 MPa or less, as measured according to the ASTM D 882 standard, and a tensile modulus of elasticity in the TD direction of 800 MPa or more, or It may be 900 MPa or more and may be 1500 MPa or less.

Accordingly, the average of the MD tensile modulus and TD tensile modulus measured according to ASTM D 882 of the biaxially stretched film may be 700 MPa or more, preferably 750 MPa or more, 780 MPa or more, or 794.5 MPa or more and 1000 MPa or less. You can.

The polyethylene biaxially stretched film has a tensile elongation in the MD direction of 150% to 250%, as measured according to the ASTM D 882 standard. Alternatively, it may be 160% to 230%, and the tensile elongation in the TD direction is 50% to 100%. Or it may be 65% to 90%.

The polyethylene biaxially stretched film may have a tear strength in the MD direction of 6 N/mm to 13.1 N/mm, as measured according to the ASTM 1922 standard, and a tear strength in the TD direction of 1.6 N/mm to 6.7 N/mm. It can be.

In addition, the polyethylene biaxially stretched film described above may have a puncture strength measured according to the EN 14477 standard of 230 N/mm or more or 230 N/mm to 450 N/mm, preferably 240 N/mm or more. , or greater than or equal to 250 N/mm, or greater than or equal to 260 N/mm, or greater than or equal to 270 N/mm, or greater than or equal to 280 N/mm, or greater than or equal to 320 N/mm, or greater than or equal to 340 N/mm, or greater than or equal to 357 N/mm, or greater than or equal to 400 N It may be less than /mm.

In the present invention, the physical properties of the biaxially stretched film can be measured according to the above-mentioned standards, and the specific method is as described in Test Example 3, which will be described later.

In the present invention, as described above, the mechanical properties are improved through blending of the first ethylene-alphaolefin copolymer, which has excellent flowability and can provide stretchability, and the second ethylene-alphaolefin copolymer, which has excellent mechanical properties. By controlling the balance between stretchability, it is possible to stably manufacture a biaxially stretched film that maintains excellent mechanical properties, productivity, and stretching stability, and has high shrinkage resistance, printability, and transparency.

The polyethylene according to the present invention maintains excellent mechanical properties, productivity, and stretching stability, and has the excellent effect of producing a biaxially stretched film with high shrinkage resistance, printability, and transparency.

Hereinafter, embodiments of the present invention will be described in more detail in the following examples. However, the following examples only illustrate embodiments of the present invention, and the content of the present invention is not limited by the following examples.

[Example]

<Preparation of metallocene compounds>

Synthesis Example 1

(1) Preparation of ligand compounds

<Synthesis of N-tert-butyl-1-(1,2-dimethyl-3H-benzo[b]cyclopenta[d]thiophen-3-yl)-1,1-dimethylsilanamine>

After adding 4.65 g (15.88 mmol) of the compound of Formula 3 in a quantitative amount to a 100 mL Schlenk flask, 80 mL of THF was added thereto. tBuNH ₂ (4eq, 6.68 mL) was added at room temperature, and then reacted at room temperature for 3 days. After the reaction, THF was removed and the mixture was filtered with hexane. After drying the solvent, a yellow liquid was obtained with a yield of 4.50 g (86%).

¹ H-NMR (500 MHz, CDCl ₃ ): δ 7.99 (d, 1H), 7.83 (d, 1H), 7.35 (dd, 1H), 7.24 (dd, 1H), 3.49 (s, 1H), 2.37 ( s, 3H), 2.17 (s, 3H), 1.27 (s, 9H), 0.19 (s, 3H), -0.17 (s, 3H).

(2) Preparation of transition metal compounds

The above ligand compound (1.06 g, 3.22 mmol/1.0eq) and 16.0 mL (0.2M) of MTBE were added to a 50 mL Schlenk flask and stirred. n-BuLi (2.64 mL, 6.60 mmol/2.05eq, 2.5M in THF) was added at -40°C and reacted at room temperature overnight. Afterwards, MeMgBr (2.68 mL, 8.05 mmol/2.5eq, 3.0M in diethyl ether) was slowly added dropwise at -40°C, and then TiCl ₄ (2.68 mL, 3.22 mmol/1.0eq, 1.0M in toluene) was added in that order. The reaction was allowed to occur overnight at room temperature. Afterwards, the reaction mixture was filtered through Celite using hexane. After drying the solvent, a brown solid was obtained with a yield of 1.07 g (82%).

¹ H-NMR (500 MHz, CDCl ₃ ): δ 7.99 (d, 1H), 7.68 (d, 1H), 7.40 (dd, 1H), 7.30 (dd, 1H), 3.22 (s, 1H), 2.67 ( s, 3H), 2.05 (s, 3H), 1.54 (s, 9H), 0.58 (s, 3H), 0.57 (s, 3H), 0.40 (s, 3H), -0.45 (s, 3H).

Synthesis Example 2

t-butyl-O-(CH ₂ ) 6 -Cl was prepared using ₆ -chlorohexanol by the method described in Tetrahedron Lett. 2951 (1988), and Na(C ₅ H ₅ ) [NaCp ] was reacted to obtain t-butyl-O-(CH ₂ ) ₆ -C ₅ H ₅ (yield 60%, bp 80 ^o C/0.1 mmHg).

In addition, t-butyl-O-(CH ₂ ) ₆ -C ₅ H ₅ was dissolved in tetrahydrofuran (THF) at -78 ^o C, n-BuLi was slowly added, the temperature was raised to room temperature, and reaction was performed for 8 hours. I ordered it. The synthesized lithium salt solution was slowly added to the suspension solution of ZrCl ₄ (THF) ₂ (170 g, 4.50 mmol) / THF (30 mL) at -78 ^o C and reacted at room temperature for another 6 hours. I ordered it. All volatile substances were removed by vacuum drying, and hexane was added to the obtained oily liquid and filtered. After vacuum drying the filter solution, hexane was added to induce precipitate at low temperature (-20 ^o C). The obtained precipitate was filtered at low temperature to obtain [t-butyl-O-(CH ₂ ) ₆ -C ₅ H ₄ ] ₂ ZrCl ₂ compound in the form of a white solid (yield 92%).

¹ H-NMR (300 MHz, CDCl ₃ ): δ 6.28 (t, J=2.6 Hz, 2H), 6.19 (t, J=2.6 Hz, 2H), 3.31 (t, 6.6 Hz, 2H), 2.62 (t , J=8 Hz), 1.7 - 1.3 (m, 8H), 1.17 (s, 9H).

¹³ C-NMR (CDCl ₃ ): δ 135.09, 116.66, 112.28, 72.42, 61.52, 30.66, 30.31, 30.14, 29.18, 27.58, 26.00.

Synthesis Example 3

After adding 50 g of Mg(s) to a 10 L reactor at room temperature, 300 mL of THF was added. After adding about 0.5 g of I2, the reactor temperature was maintained at 50°C. After the reactor temperature was stabilized, 250 g of 6-t-butoxyhexyl chloride was added to the reactor at a rate of 5 mL/min using a feeding pump. It was observed that the reactor temperature increased by about 4 to 5 °C as 6-t-butoxyhexyl chloride was added. The mixture was stirred for 12 hours while continuously adding 6-t-butoxyhexyl chloride. After 12 hours of reaction, a black reaction solution was obtained. After taking 2 mL of the resulting black solution, water was added to obtain an organic layer, and 6-t-butoxyhexane was confirmed through ¹ H-NMR. It was confirmed from the 6-t-butoxyhexane that the Gringanrd reaction proceeded well. Thus, 6-t-butoxyhexyl magnesium chloride was synthesized.

After adding 500 g of MeSiCl ₃ and 1 L of THF to the reactor, the temperature of the reactor was cooled to -20°C. 560 g of the synthesized 6-t-butoxyhexyl magnesium chloride was added to the reactor at a rate of 5 mL/min using a feeding pump. After the feeding of the Grignard reagent was completed, the reactor temperature was slowly raised to room temperature and stirred for 12 hours. After 12 hours of reaction, it was confirmed that white MgCl ₂ salt was produced. 4 L of hexane was added and the salt was removed through labdori to obtain a filter solution. The obtained filter solution was added to the reactor and hexane was removed at 70°C to obtain a pale yellow liquid. The obtained liquid was confirmed to be the desired methyl(6-t-butoxy hexyl)dichlorosilane {Methyl(6-t-butoxy hexyl)dichlorosilane} compound through ^1H -NMR.

¹ H-NMR (300 MHz, CDCl ₃ ): δ 3.3 (t, 2H), 1.5 (m, 3H), 1.3 (m, 5H), 1.2 (s, 9H), 1.1 (m, 2H), 0.7 ( s, 3H).

1.2 mol (150 g) of tetramethylcyclopentadiene and 2.4 L of THF were added to the reactor, and the temperature of the reactor was cooled to -20°C. n-BuLi 480 mL was added to the reactor at a rate of 5 mL/min using a feeding pump. After adding n-BuLi, the reactor temperature was slowly raised to room temperature and stirred for 12 hours. After 12 hours of reaction, an equivalent amount of methyl(6-t-butoxy hexyl)dichlorosilane (326 g, 350 mL) was quickly added to the reactor. The reactor temperature was slowly raised to room temperature while stirring for 12 hours, and then the reactor temperature was cooled to 0° C. and then 2 equivalents of t-BuNH ₂ was added. The reactor temperature was slowly raised to room temperature and stirred for 12 hours. After 12 hours of reaction, THF was removed, 4 L of hexane was added, and a filter solution from which salts were removed was obtained through labrador. After adding the filter solution back to the reactor, hexane was removed at 70°C to obtain a yellow solution. The yellow solution obtained was confirmed to be a methyl(6-t-butoxyhexyl)(tetramethylCpH)t-butylaminosilane compound through ¹ H-NMR. did.

TiCl ₃ (THF) ₃ (10 mmol) was synthesized from n-BuLi and the ligand dimethyl(tetramethylCpH)t-Butylaminosilane in a THF solution at -78°C. ) was applied quickly. The reaction solution was stirred for 12 hours while slowly raising the temperature from -78°C to room temperature. After stirring for 12 hours, an equivalent amount of PbCl ₂ (10 mmol) was added to the reaction solution at room temperature and stirred for 12 hours. After stirring for 12 hours, a dark black solution with a blue tinge was obtained. After THF was removed from the resulting reaction solution, hexane was added and the product was filtered. After removing hexane from the filter solution, the desired ([methyl(6-t-buthoxyhexyl)silyl(η5-tetramethylCp)(t-Butylamido)]TiCl ₂ ), (tBu-O-(CH ₂ ), was obtained from ¹ H-NMR. ₆ )(CH ₃ )Si(C ₅ (CH ₃ ) ₄ )(tBu-N)TiCl ₂ was confirmed.

¹ H-NMR (300 MHz, CDCl ₃ ): δ 3.3 (s, 4H), 2.2 (s, 6H), 2.1 (s, 6H), 1.8 ~ 0.8 (m), 1.4 (s, 9H), 1.2 ( s, 9H), 0.7 (s, 3H).

<Manufacture of supported catalyst>

Catalyst Preparation Example 1: Preparation of hybrid supported metallocene catalyst

5.0 kg of toluene solution was added to a 20L sus high pressure reactor, and the reactor temperature was maintained at 40°C. 1000 g of silica (SYLOPOL 948, manufactured by Grace Davison) dehydrated by applying vacuum at a temperature of 600° C. for 12 hours was added to the reactor and the silica was sufficiently dispersed, followed by 80 g of the first metallocene compound obtained in Synthesis Example 2. was dissolved in toluene and reacted by stirring at 40°C and 200 rpm for 2 hours. Afterwards, stirring was stopped, allowed to settle for 30 minutes, and then the reaction solution was decantated.

2.5 kg of toluene was added to the reactor, 9.4 kg of 10 wt% methylaluminoxane (MAO)/toluene solution was added, and the mixture was stirred at 40°C and 200 rpm for 12 hours. After reaction, stirring was stopped, settling was performed for 30 minutes, and then the reaction solution was decantated. After adding 3.0 kg of toluene and stirring for 10 minutes, stirring was stopped, settling was performed for 30 minutes, and the toluene solution was decantated.

3.0 kg of toluene was added to the reactor, and 314 mL of the 29.2 wt% second metallocene compound/toluene solution obtained in Synthesis Example 3 was added to the reactor, and the mixture was stirred at 40°C and 200 rpm for 2 hours to react. At this time, the molar ratio of the first metallocene compound and the second metallocene compound was 1:5 (number of moles of the first metallocene compound: number of moles of the second metallocene compound). After lowering the reactor temperature to room temperature, stirring was stopped and the reaction solution was allowed to settle for 30 minutes and then decantated.

2.0 kg of toluene was added to the reactor and stirred for 10 minutes, then stirring was stopped and allowed to settle for 30 minutes before decantation of the reaction solution.

3.0 kg of hexane was added to the reactor, the hexane slurry was transferred to a filter dryer, and the hexane solution was filtered. A 910g-SiO ₂ hybrid supported catalyst was prepared by drying under reduced pressure at 40°C for 4 hours.

<Preparation of ethylene-alpha olefin copolymer>

Preparation Example 1: Preparation of ethylene/1-octene copolymer (PE-a)

A 1.5 L continuous process reactor was preheated at 120°C while adding 5 kg/h of hexane solvent and 0.31 kg/h of 1-octene. Triisobutylaluminum (Tibal, Triisobutylaluminum, 0.045 mmol/min), the transition metal compound obtained in Synthesis Example 1, and dimethylanilinium tetrakis(pentafluorophenyl)borate cocatalyst (2.6 μmol/min) were simultaneously added to the reactor. It was put in. Next, ethylene (0.87 kg/h) and hydrogen gas (10 cc/min) were introduced into the reactor and the copolymerization reaction was performed by maintaining the temperature at 160.0°C for more than 60 minutes in a continuous process at a pressure of 89 bar to produce ethylene/1-octene. A copolymer (PE-a) was obtained.

Preparation Example 2: Preparation of ethylene/1-hexene copolymer (PE-b)

Ethylene/1-hexene copolymer (PE-b) was slurry polymerized in the presence of the supported hybrid catalyst prepared in Catalyst Preparation Example 1.

At this time, the polymerization reactor was a continuous polymerization reactor using an isobutane (i-C4) slurry loop process, the reactor volume was 140 L, and the reaction flow rate was operated at about 7 m/s. The gases required for polymerization (ethylene, hydrogen) and the comonomer 1-hexene were constantly and continuously introduced, and the individual flow rates were adjusted to suit the target product. At this time, the ethylene supply amount was adjusted to 31.1 kg/hr, the 1-hexene input amount was adjusted to 2.5 wt% compared to ethylene, and the hydrogen input amount was adjusted to 56 ppm compared to ethylene. In addition, the concentrations of all gases and comonomer 1-hexene in Preparation Example 1 were confirmed using an on-line gas chromatograph. The supported catalyst was prepared and added as an isobutane slurry with a concentration of 4% by weight, the reactor pressure was maintained at about 40 bar, and the polymerization temperature was performed at about 80 ^o C.

<Test Example 1: Evaluation of physical properties of polyethylene>

The physical properties of the ethylene-alpha olefin copolymers prepared in Preparation Examples 1 and 2 were measured by the method described below and are shown in Table 1.

(1) Melt index

According to the American Society for Testing and Materials standard ASTM D 1238 (condition E, 190 ^o C, 2.16 kg), the melt index (MI _2.16 ) was measured at 190 ^o C with a load of 2.16 kg (Measurement equipment: Gottfert MI- 4), expressed as the weight (g) of the polymer melted for 10 minutes.

(2) Density

Density (g/cm ³ ) was measured using a density gradient pipe according to the American Society for Testing and Materials ASTM D 1505 standard.

(3) Number average molecular weight, weight average molecular weight, and molecular weight distribution

Using gel permeation chromatography (GPC, gel permeation chromatography, manufactured by Water) for the ethylene-alpha olefin copolymers prepared in Preparation Examples 1 and 2, the weight average was calculated according to the American Society for Testing and Materials ASTM D 6474 standard. Molecular weight (Mw, g/mol) and number average molecular weight (Mn, g/mol) were measured, and molecular weight distribution (Mw/Mn, PDI, polydispersity index) was calculated by dividing the weight average molecular weight by the number average molecular weight.

Specifically, a gel permeation chromatography (GPC) device, PL-GPC220 from Waters, was used, and a 300 mm long column from Polymer Laboratories PLgel MIX-B was used. At this time, the measurement temperature was 160°C, 1,2,4-trichlorobenzene was used as a solvent, and the flow rate was 1 mL/min. Each sample of the ethylene-alphaolefin copolymer prepared in Preparation Examples 1 and 2 was analyzed at 160% in trichlorobenzene (1,2,4-Trichlorobenzene) containing 0.0125% BHT using a GPC analysis device (PL-GP220). ^o C, pretreated by melting for 10 hours, 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 a polystyrene standard specimen. The weight average molecular weight of polystyrene standard specimens is 2000 g/mol, 10000 g/mol, 30000 g/mol, 70000 g/mol, 200000 g/mol, 700000 g/mol, 2000000 g/mol, 4000000 g/mol, 10000000 g. Nine types of /mol were used.

Comonomer MI _2.16
(g/10min) density
(g/ ^cm3 ) Mn
(g/mol) Mw
(g/mol) Mw/Mn Manufacturing Example 1
(PE-a) 1-octene 6.0 0.900 30000 68000 2.3 Preparation Example 2 (PE-b) 1-hexene 0.6 0.941 28000 114000 4.1

Comparative Manufacturing Example 1

ME1000™ (manufactured by LG Chemicals), a commercially available ethylene/1-butene copolymer polyethylene product manufactured using a Ziegler-Natta catalyst, was used in Comparative Preparation Example 1 (PE-c).

Comparative Manufacturing Example 2

SP380™ (manufactured by LG Chemical), a commercially available homopolyethylene product manufactured with a metallocene catalyst, was used in Comparative Preparation Example 2 (PE-d).

<Preparation of polyethylene composition>

Examples 1 to 3 and Comparative Examples 1 to 3

Using the ethylene-alphaolefin copolymer or ethylene homopolymer (homo PE) of Preparation Examples 1 to 2 and Comparative Preparation Examples 1 to 2 described above, Examples 1 to 3 and Comparative Preparation Examples were prepared, respectively, with the compositions shown in Table 2 below. The polyethylene compositions of Examples 1 to 3 were prepared.

Specifically, a polyethylene composition was manufactured by extrusion and granulation using twin extruder equipment under the conditions of hopper 18 rpm, screw 350 rpm, and 220 ℃ (extruder: SMPLATEK TEK30MHS, L/D ratio = 40, die diameter: 4 mm).

<Test Example 2: Evaluation of physical properties of polyethylene composition>

The physical properties of the polyethylene compositions prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were measured by the method described below and are shown in Table 2.

First, the melt index (MI _2.16 ), density, weight average molecular weight (Mw, g/mol), number average molecular weight (Mn, g/mol), and molecular weight distribution (Mw/Mn, PDI) for the polyethylene composition. was measured in the same manner as in Test Example 1.

(4) Melting temperature and crystallization temperature, crystallinity degree

Melting temperature (Tm) and crystallization of the polyethylene compositions of Examples 1 to 3 and Comparative Examples 1 to 3 using a Differential Scanning Calorimeter (DSC, device name: DSC Q20, manufacturer: TA instrument) Temperature (Crystallization Temperature, Tc) and crystallinity (Xc) were measured.

Specifically, the polyethylene composition was heated to 180°C at 10°C/min by raising the temperature (Cycle 1), isothermalized at 180°C for 5 minutes, cooled to 0°C at 10°C/min, and then isothermalized at 30°C for 5 minutes. Then, it was heated again at 10°C/min to 180°C (Cycle 2). In the DSC curve obtained through this, the temperature of the maximum point of the endothermic peak was measured as the melting temperature (Tm, ℃), and the temperature of the maximum point of the exothermic peak was measured as the crystallization temperature (Tc, ℃). At this time, the melting temperature (Tm) and crystallization temperature (Tc) are shown as the results of measurements in the section (Cycle 2) where the second temperature rises and falls, respectively.

In addition, in the section where the second temperature rises (Cycle 2), Heat of Fusion △Hm is calculated as the area of the melting peak, and this is divided by H ⁰ m = 293.6 J/g, which is the theoretical value when the crystallinity is 100%, to calculate the crystallinity ( Xc, %) was calculated.

(5) Cross Fractionation Chromatography (CFC) analysis

Cross-fraction chromatography (CFC) analysis was performed on the polyethylene compositions of Examples 1 to 3 and Comparative Examples 1 to 2 by the method below, and the main chain weight average molecular weight of the highly crystalline fraction eluted at 90 ° C. or higher was determined. (Mw _{main, T≥90℃} ), the content ratio of the highly crystalline fraction eluted above 90 ℃ (TREF _{, T≥90℃} ), and the content ratio of the medium-low crystalline fraction eluted below 90 ℃ (TREF _{, T<90 ℃} ) was measured.

Cross-fraction chromatography (CFC) measurement conditions (including TREF and GPC-IR analysis)

- Analysis equipment: Polymer Char CFC (Detector: Integrated Detector IR5 MCT)

- Sample preparation and input: Put 32 mg of polyethylene composition in a 10 mL vial and place it in the autosampler, add 8 mL of 1,2,4-trichlorobenzene (TCB), and then cool to 90 degrees Celsius at 160 ^o C. Dissolve for minutes, extract after Nitrogen purge, and load into a temperature rising elution fractionation column (TREF column).

- Crystallization: The sample previously loaded on the TREF column is set to 100 ℃, then cooled from 100 ℃ to 35 ℃ at a rate of 0.5 ℃/min.

- Temperature rising elution temperature (TREF) analysis: The crystallized sample was held at 1°C intervals from 35°C to 120°C, and the fractions eluting at each temperature for 25 minutes were analyzed. Specifically, extraction and analysis were performed at 35°C for 25 minutes, then extraction and analysis were performed by raising the temperature at 1°C intervals, and finally extraction and analysis were performed at 120°C for 25 minutes.

- GPC-IR analysis: In the TREF analysis, the fractions eluted at each temperature were moved to the GPC column of the GPC (PL-GPC220) device, the molecular weight of the eluted molecules was measured, and the PerkinElmer Spectrum connected to the GPC (PL-GPC220) was used. 100 Using FT-IR, the number of short-chain branches (scb) of molecules eluted at each temperature was measured.

- Average molecular weight of the main chain of the highly crystalline fraction (Mw _main , _{T≥90 ℃} ) Calculation: Main chain excluding the short-chain branch part among the fractions eluted above 90 ℃ previously confirmed through CFC analysis ) The weight average molecular weight (Mw _{main, T≥90°C} , g/mol) of the portion was calculated according to Equation 1 below.

[Equation 1]

Mw _{main,T≥90℃} (g/mol) =

In equation 1 above,

M _T,i and C _T,i are the weight average molecular weight (g/mol) and concentration of each fraction eluted at each temperature through the CFC analysis,

n ^scb _T,i is the number of branched chains (scb) of each fraction eluted at each temperature through the previous CFC analysis,

M _scb is the weight average molecular weight (g/mol) of the branched chain (scb) of each fraction eluted at each temperature through CFC analysis.

- Content ratio of highly crystalline fractions (TREF _{, T≥90°C} ): Based on the total weight of all eluted fractions previously obtained through CFC analysis, the content ratio of highly crystalline fractions eluted above 90°C was calculated as a percentage (%).

- Content ratio of high-crystalline fraction (TREF _{, T<90℃} ): Based on the total weight of all eluted fractions obtained through CFC analysis, the content ratio of low- to medium-crystalline fractions eluted below 90℃ was calculated as a percentage (%). .

(6) Measurement of stress relaxation time

Stress relaxation time was measured for the polyethylene compositions of Examples 1 to 3 and Comparative Examples 1 to 2.

Specifically, the stress relaxation time (relaxation time, seconds) of the polyethylene composition was calculated as Strain 0.5%, Frequency using ARES-G2, a rotational rheometer from TA Instruments (New Castle, Delaware, USA). Measure the viscosity at each temperature at an angular frequency of 0.05 rad/s to 500 rad/s at 150 ℃, 170 ℃, 190 ℃, 210 ℃, and 230 ℃ under conditions of 0.1 to 500 rad/s. did. From the viscosity values for each temperature measured in this way, the stress relaxation time (Relaxation time, seconds) for each temperature was calculated using the cross model of Equation 2 below.

[Equation 2]

η = η _∞ + (η ₀ - η _∞ ) / (1 + λ × (Shear rate) ^m )

In equation 2 above,

The η is measured using a rotational rheometer under the conditions of each measurement temperature of 150 ℃, 170 ℃, 190 ℃, 210 ℃, and 230 ℃ and angular frequency of 0.05 rad/s to 500 rad/s. This is the measured viscosity of polyethylene,

The η _∞ is the infinite shear viscosity,

The η ₀ is the zero shear viscosity,

The shear rate is the shear rate applied to polyethylene and is the same value as the angular frequency,

The λ and m are parameters obtained by fitting a log-log graph with the angular frequency as the x-axis and the viscosity measurement value η as the y-axis using the cross model of Equation 2,

The λ is the stress relaxation time (Relaxation time, seconds) of the polyethylene composition and is the reciprocal of the Angular Frequency at which the viscosity η begins to decrease,

The m is the slope of viscosity η in the region where viscosity η decreases.

In addition, the stress relaxation time (RT 120°C) at 120 _° C was calculated through an Arrhenius plot based on the stress relaxation time (relaxation time, seconds) at each temperature measured as described above. .

For example, after calculating the Arrhenius constant (A) through an Arrhenius plot based on the stress relaxation time (relaxation time, seconds) at each temperature, the stress relaxation time of the polyethylene composition was calculated according to Equation 3 below. did.

[Equation 3]

lnK = LnA + E _a /RT

In equation 3 above,

K is the stress relaxation time (Relaxation time, seconds) of the polyethylene composition,

Ea is the activation energy (J/mol),

R is the gas constant (8.314 J/mol·K),

A is the Arrhenius constant,

T is absolute temperature (Kelvin).

Example 1 Example 2 Example 3 Comparative Example 1 Comparative example 2 Comparative example 3 Polyethylene composition PE-a 30wt%+
PE-b 70wt% PE-a 20wt%+
PE-b 80wt% PE-a 15wt%+
PE-b 85wt% PE-a 30wt%+
PE-c 70wt% PE-c 100wt% PE-a 30wt%+
PE-d 70wt% (homo PE) MI _2.16 (g/10min) 1.1 0.9 0.8 1.6 1.0 1.0 Density (g/cm ³ ) 0.931 0.935 0.937 0.94 0.952 0.939 Mn (g/mol) 31000 30000 31000 8900 7400 37000 Mw (g/mol) 106000 111000 116000 115000 133000 109000 Mw/Mn 3.4 3.7 3.7 12.9 18 3 Tm (℃) 127.9 128.4 128.6 130.3 131.4 132.9 Tc (℃) 113.7 113.4 114.1 116.1 116.8 116.3 Xc (%) 40.8 43.9 43.7 51.8 63.3 45.8 Highly crystalline main chain weight average molecular weight,
Mw _{main,T≥90℃}
(g/mol) 117100 116300 113700 197200 195600 152100 Highly crystalline molecule elution rate,
TREF _≥90℃ (%) 50.9 59.6 64.1 50.7 73.1 68.9 Low/medium crystallinity
Molecular elution rate,
TREF _<90℃ (%) 49.1 40.4 35.9 49.3 26.9 31.1 120℃ Relaxation time, RT _120℃ (s) 2.2 2.1 2 10.1 5.1 4.3

<Test Example 3: Preparation and physical property evaluation of biaxially stretched film>

Biaxially stretched films were prepared using the polyethylene compositions prepared in Examples 1 to 3 and Comparative Examples 1 to 2 in the following manner, and then the respective physical properties were measured and shown in Table 3.

Preparation of biaxially stretched films

- Manufacture polyethylene composition sheets with a thickness of 0.75 mm using Bruckner's lab extruder line (L/D ratio: 42, Screw diameter: 25 mm, Melt/T-Die temperature: 220 ℃)

- Using KARO 5.0 equipment, biaxial stretching is performed on a polyethylene composition sheet measuring 90 mm x 90 mm in length.

- Sequential stretching (MD → TD) was performed after preheating for 80 seconds under the following conditions (Example 1: preheating and stretching at 120 ℃ conditions, Example 2: preheating and stretching at 125 ℃ conditions, Example 3: 122 ℃ conditions (preheating and stretching, Comparative Example 1: preheating and stretching at 115 ℃, Comparative Example 2: preheating and stretching at 125 ℃), Comparative Example 3: Stretching was attempted under the same conditions as Comparative Example 2, but it was determined that stretching was not possible.

Evaluation of biaxially stretched film properties

- Tensile strength (MPa), tensile modulus (MPa), and tensile elongation (%): measured in each MD/TD direction according to ASTM D 882 standard.

- Tear strength (N/mm): ASTM 1922 standard, measured in each MD/TD direction

- Haze (%): Measured according to ASTM 1003 standards

- Glossiness (gloss 45 ^o ): Measured according to ASTM 2457 standards

- Shrinkage rate (%): Measurement of length change rate after shrinkage at 100 ℃ or 120 ℃ for 7 minutes according to ASTM D 1204 standard. Specifically, shrinkage rate (%) is measured as [(1 - length after shrinkage)/length before shrinkage]

- Puncture strength (N/mm): Measured according to EN 14477 standard

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Maximum stretching ratio (MD×TD) 5×8 5×8 4×6 4×6 4×6 Stretching is not possible Haze(%) 1.6 1.7 1.9 2.0 9.5 - Gloss( ^45o ) 94 94 93 90 61 - tensile strength
(Mpa) M.D. 130 134 123 90 62 - TD 203 200 203 134 102 - MD, TD average 166.5 167 163 112 82 - tensile modulus
(Mpa) M.D. 645 770 653 308 657 - TD 944 1007 940 383 689 - MD, TD average 794.5 888.5 796.5 345.5 673 - tensile elongation
(%) M.D. 220 223 164 267 329 - TD 87 86 65 131 155 - MD, TD average 153.5 154.5 114.5 199 242 - Tear strength
(N/mm) M.D. 13.1 11.1 6.5 51.5 15.4 - TD 6.4 3.7 1.6 26.8 7.0 - MD, TD average 9.75 7.4 4.05 39.15 7.7 - shrinkage rate
(@100, %) M.D. 0.8 0.8 0.8 2.5 0.8 - TD 5.0 4.2 2.9 10.0 2.1 - MD+TD 5.8 5.0 3.7 12.5 2.9 - shrinkage rate
(@120, %) M.D. 5.0 4.6 7.9 9.9 1.7 - TD 15.8 14.2 21.3 33.3 7.1 - MD+TD 20.8 18.8 29.2 43.2 8.8 - Puncture strength (N/mm) 357.0 388.3 362.0 269.8 211.4 -

According to the results in Tables 2 and 3, the compositions of the examples that meet the main chain weight average molecular weight range of the predetermined highly crystalline fraction have excellent stretchability and stretching stability due to excellent stretching stability and high shrinkage resistance when manufactured as a biaxially stretched film. It was confirmed that it exhibited excellent mechanical properties compared to the comparative example.

Claims (19)

A polyethylene composition comprising at least one ethylene-alphaolefin copolymer,
The polyethylene composition has a main chain weight average molecular weight (Mw _{main, T≥90°C} ) of the highly crystalline fraction eluted above 90°C when analyzed by cross fractionation chromatography (CFC) of 150,000 g/mol or less,
Polyethylene composition.
According to paragraph 1,
The polyethylene composition,
(a) a first ethylene-alphaolefin aerosol having a density of 0.870 g/cm ³ to 0.920 g/cm ³ and a melt index (MI _2.16 , 190 ^o C, 2.16 kg load) of 3.0 g/10min to 10.0 g/10min. coalescence, and
(b) a second ethylene-alphaolefin aerosol having a density of 0.930 g/cm ³ to 0.960 g/cm ³ and a melt index (MI _2.16 , 190 ^o C, 2.16 kg load) of 0.2 g/10 min to 2.0 g/10 min. coalescence
Including,
Polyethylene composition.
According to paragraph 1,
The polyethylene composition,
When analyzed by cross fractionation chromatography (CFC), the main chain weight average molecular weight (Mw _{main, T≥90°C} ) of the highly crystalline fraction eluted above 90°C is 50,000 g/mol to 150,000 g/mol,
Polyethylene composition.
According to paragraph 1,
The polyethylene composition,
When analyzing cross fractionation chromatography (CFC), the content ratio of the highly crystalline fraction eluted above 90 ℃ (TREF _{, T≥90 ℃} ) is more than 50% of the total weight of all eluted fractions,
Polyethylene composition.
According to paragraph 1,
The polyethylene composition,
When analyzing cross fractionation chromatography (CFC), the content ratio (TREF _{, T<90°C) of the low-to-medium crystalline fraction eluted below 90°C} is less than 50% of the total weight of all eluted fractions.
Polyethylene composition.
According to paragraph 1,
The polyethylene composition,
Stress relaxation time (RT 120°C) at _120°C is less than 4.0 seconds,
Polyethylene composition.
According to paragraph 1,
The polyethylene composition,
The density is 0.928 g/cm ³ to 0.942 g/cm ³ ,
a melt index (MI _2.16 , 190 ^o C, 2.16 kg load) of 0.6 g/10min to 1.5 g/10min,
Polyethylene composition.
According to paragraph 1,
The polyethylene composition,
The number average molecular weight Mn is more than 25000 g/mol
The weight average molecular weight Mw is 105000 g/mol or more,
Molecular weight distribution Mw/Mn is 5.0 or less,
Polyethylene composition.
According to paragraph 1,
The polyethylene composition,
The melting point Tm is 125°C to 129°C,
The crystallization temperature Tc is 112°C to 115°C,
Crystallinity Xc is 35% to 48%,
Polyethylene composition.
According to paragraph 2,
(a) containing more than 0 to 40% by weight of the first ethylene-alpha olefin copolymer,
(b) comprising 60% by weight or more and less than 100% by weight of the second ethylene-alpha olefin copolymer,
Polyethylene composition.
According to paragraph 2,
The (a) first ethylene-alpha olefin copolymer,
The number average molecular weight Mn is more than 20000 g/mol
The weight average molecular weight Mw is 60000 g/mol or more and less than 95000 g/mol,
The molecular weight distribution Mw/Mn is 2.0 or more and less than 3.5,
Polyethylene composition.
According to paragraph 2,
The first ethylene-alphaolefin copolymer (a) is 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetra Containing one or more alpha-olefins selected from the group consisting of decene, 1-hexadecene, 1-octadecene, and 1-eicocene,
Polyethylene composition.
According to paragraph 2,
The (a) first ethylene-alpha olefin copolymer is an ethylene/1-octene copolymer,
Polyethylene composition.
According to paragraph 2,
The (b) second ethylene-alpha olefin copolymer is,
The number average molecular weight Mn is more than 20000 g/mol
The weight average molecular weight Mw is 95000 g/mol or more to 150000 g/mol,
The molecular weight distribution Mw/Mn is 3.5 or more and 4.8 or less,
Polyethylene composition.
According to paragraph 2,
The second ethylene-alphaolefin copolymer (b) is 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetra Containing one or more alpha-olefins selected from the group consisting of decene, 1-hexadecene, 1-octadecene, and 1-eicocene,
Polyethylene composition.
According to paragraph 2,
The (b) second ethylene-alpha olefin copolymer is an ethylene/1-hexene copolymer,
Polyethylene composition.
A biaxially stretched film comprising the polyethylene composition of claim 1.
According to clause 17,
The film satisfies MD draw ratio of 4 or more and TD draw ratio of 6 or more,
Biaxially stretched film.
According to clause 17,
The film, under the conditions of satisfying MD draw ratio of 4 or more and TD draw ratio of 6 or more,
According to ASTM 1204 standard, the total shrinkage rate in MD/TD direction is 6.0% or less when shrinked at 100 ℃ for 7 minutes, or
According to ASTM 1204 standard, the total shrinkage rate in MD/TD direction is 22.0% or less when shrinking at 120 ℃ for 7 minutes.
Biaxially stretched film.