KR102713279B1 - Polyethylene copolymer and blown film comprising the same - Google Patents

Abstract

The present invention relates to polyethylene capable of producing a blown film having excellent heat shrinkage packaging performance due to a large shrinkage ratio in the transverse direction (TD) of the resin flow even at low temperatures without increasing the temperature to high temperatures.

Description

{POLYETHYLENE COPOLYMER AND BLOWN FILM COMPRISING THE SAME}

The present invention relates to a polyethylene copolymer capable of producing a blown film having excellent heat shrinkage packaging performance due to a large shrinkage ratio in the transverse direction (TD) of resin flow even at low temperatures without increasing the temperature to high temperatures.

Low density polyethylene (LDPE) is manufactured by copolymerizing ethylene and alpha olefin at high pressure using an initiator, and is used in shrink films.

In general, shrink films have been used for many years in the packaging industry for packaging goods. The process involves packing the goods, passing them through an oven tunnel to heat and cool them, thereby causing the film to shrink, and is applied to collation shrink films for general consumer goods and beverages. It is known that linear low density polyethylene (LLDPE) mixed with low density polyethylene (LDPE) is used among shrink film compositions. Typically, a composition containing 20 to 40 wt% of LLDPE together with 80 to 60 wt% of LDPE is used. However, when LLDPE is mixed with LDPE to improve mechanical properties, there is a problem that shrinkage properties deteriorate.

Meanwhile, in the case of collation shrink film, medium density polyethylene is used to increase stiffness for stability when loading, moving, and storing products. Among them, heat shrink film is applied to industrial packaging, food, beverage, and general product packaging. Most of these films are formed by blown extruders, and the shrinkage ratio in the transverse direction (TD) of the resin flow determines the packaging performance.

Accordingly, there is a need to develop a medium-density polyethylene resin that improves the shrinkage characteristics in the transverse direction (TD) of the resin flow even in a low-temperature heat shrinkage process.

The present invention provides polyethylene capable of producing a blown film having excellent heat shrinkage packaging performance and a blown film comprising the same.

In one embodiment of the present invention, a polyethylene copolymer is provided having a density of 0.925 g/cm ³ to 0.940 g/cm ³ , a melt index (MI _2.16 , 190 ^o C, 2.16 kg load) of 0.2 g/10 min to 1.0 g/10 min, and a content of a branched polymer structure of 25 wt% to 35 wt% based on the total weight of the polyethylene copolymer.

In addition, in another embodiment of the present invention, a blown film comprising the polyethylene copolymer of the above embodiment is provided.

The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the invention.

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

In this specification, the terms “comprise,” “include,” or “have” are intended to describe a feature, number, step, component, or combination thereof implemented, but do not exclude the possibility of one or more other features, numbers, steps, components, combinations, or additions thereof.

In addition, the terms “about,” “substantially,” and the like used throughout this specification are used in a meaning that is at or close to the numerical value when manufacturing and material tolerances inherent in the meanings mentioned are presented, and are used to prevent unscrupulous infringers from unfairly utilizing the disclosure in which exact or absolute values are mentioned to aid the understanding of the present invention.

Additionally, in the present invention, (co)polymer means both a homopolymer and a copolymer.

Unless otherwise defined herein, “copolymerization” may mean a block copolymer, a random copolymer, a graft copolymer or an alternating copolymer, and “copolymer” may mean a block copolymer, a random copolymer, a graft copolymer or an alternating copolymer.

The present invention may have various modifications and may take various forms, and specific embodiments are exemplified and described in detail below. However, this does not limit the present invention to a specific disclosed form, but should be understood to include all modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention.

Hereinafter, the present invention will be described in detail.

According to one aspect of the present invention, a polyethylene copolymer is provided, having a density of 0.925 g/cm ³ to 0.940 g/cm ³ , a melting index (MI _2.16 , 190 ^o C, 2.16 kg load) of 0.2 g/10 min to 0.5 g/10 min, and a content of a branched polymer structure of 25 wt% to 35 wt% based on the total weight of the polyethylene copolymer.

For reference, in this specification, "part by weight" means a relative concept in which the weight of a substance is expressed as a ratio based on the weight of the remaining substance. 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 are 40 parts by weight and 60 parts by weight, respectively, based on 100 parts by weight of substance A.

Meanwhile, "% by weight" refers to an absolute concept that expresses the weight of a certain substance as a percentage of the total weight. In the mixture in the example above, the contents of substance A, substance B, and substance C out of 100% of the total weight of the mixture are 50% by weight, 20% by weight, and 30% by weight, respectively.

In the present invention, the polyethylene copolymer is a polymer in which polymers having different shapes, such as linear or branched, are mixed by physical force. For example, the branched polymer may be a polymer in which the weight average molecular weight ratio of the side chain to the main chain is 40% or less, or the weight average molecular weight of the side chain alone is 3,000 g/mol or more. In addition, the branched polymer may also be called a comb polymer.

In addition, in the present invention, the content of the branched polymer structure included in the polyethylene copolymer and the weight average molecular weight of the main chain in the structure can be analyzed using a conventional method such as GPC column analysis and NMR analysis, but in the present invention, the method can be performed by a quantitative analysis method of a polymer structure including a step of measuring the rheological properties and/or molecular weight distribution of an arbitrarily selected polymer, setting an arbitrary value for the selected polymer, predicting the rheological properties and/or molecular weight distribution of the polymer from the arbitrary value, and comparing the actually measured value with the predicted value to determine the value of the structural parameter of the polymer. More specifically, the quantitative analysis method of the polymer structure includes a step of (A) measuring the rheological properties of the polymer; (B) selecting at least one parameter among structural parameters that the polymer may have and assigning a random value to the selected structural parameter; And (C) a step of predicting the rheological properties of a polymer to which an arbitrary value is assigned, and comparing the predicted rheological properties of the polymer with the measured rheological properties of the polymer to determine the values of the structural parameters of the polymer, wherein step (A) may additionally include a step of measuring the molecular weight distribution of the polymer using GPC.

In the quantitative analysis method of the above polymer structure, the rheological properties of the polymer can be measured using a rheometer, and more specifically, the shear storage modulus (G'), the shear loss modulus (G"), and the shear complex viscosity (η*) can be measured using a rotational rheometer.

In addition, in the step (B), the structural parameters selected may be at least one selected from the group consisting of polymer shape; weight average molecular weight (Mw) of the main chain or long side chains in the branched polymer structure; polydispersity index (PDI) of the main chain or long side chains; and number of long side chains. The polymer shape parameter is a parameter that can distinguish whether the polymer to be analyzed is a linear or branched polymer, and specifically, represents a parameter that can qualitatively distinguish branched polymers that can appear in a comblike shape, a star shape, or an H shape depending on the side chain bonded to the branched polymer.

The above structural parameters may additionally include mass fractions between the polymers in the mixture. For example, the weight average molecular weight and polydispersity index parameters of each polymer in the polymer mixture may be calculated in a multiplicative manner with the mass fraction parameters, and applied to predict rheological properties and/or molecular weight distribution in step (c).

In addition, in the step (c), the rheological properties of the polymer can be predicted from the stress relaxation behavior of the polymer induced by the step strain of shear flow applied to the polymer to which an arbitrary value is assigned. The stress relaxation behavior can vary depending on the length of the main chain and side chains of the polymer, the molecular weight distribution, and the hierarchical structure. The stress change behavior appears differently depending on the structure of the polymer. For example, when the step strain of shear flow is applied to the polymer, the shape of the polymer is also deformed, and the length of the main chain and side chains of the polymer, the molecular weight distribution, and the hierarchical structure of the side chain can affect the process in which the polymer is relaxed through the stress relaxation behavior over time. As an example, in the case of a general linear polymer without a side chain, the longer the main chain, the greater the influence of the surrounding polymer, so the time required for relaxation can increase. Additionally, in the case of polymers with side chains, the relaxation time may be longer than that of linear polymers because the main chain cannot be relaxed unless the side chains are relaxed.

Additionally, the prediction of rheological properties from the above stress relaxation behavior can be made using the Doi-Edwards numerical analysis model.

In addition, the comparison of the predicted rheological property value of the polymer with the measured rheological property value of the polymer in step (C) can be performed by calculating the error value (ε) between the predicted rheological property value of the polymer and the measured rheological property value of the polymer and checking whether the error value is less than a predetermined error criterion value (εs), and in step (c), the determination of the structural parameter value of the polymer can be performed such that, if the error value is less than the predetermined error criterion value, the arbitrary value assigned in step (B) can be the determined value of the polymer structural parameter. In addition, the determined value may have a range expressed as a minimum and a maximum of a plurality of determined values derived by repeating steps (B) and (C) twice or more, and may also have an average value for a plurality of determined values derived by repeating steps (B) and (C) twice or more.

In addition, the step (C) may additionally include a step of predicting the molecular weight distribution of the polymer to which a random value is assigned, and comparing the predicted molecular weight distribution value of the polymer with the measured molecular weight distribution value of the polymer to determine the value of the structural parameter of the polymer, and the prediction of the molecular weight distribution of the polymer may be performed by assuming a log normal distribution for the polymer to which a random value is assigned.

According to one embodiment of the present invention, the polyethylene copolymer should have a branched polymer structure content of 25 wt% to 35 wt% based on the total weight of the polyethylene copolymer, as measured by the above-described method under conditions satisfying the ranges of the above-described density and melt index. If the content of the branched polymer structure is too low, less than 25 wt%, the shrinkage ratio in the TD direction decreases in a low-temperature heat shrinkage process, the heat shrinkage packaging performance deteriorates, and problems in processability and packaging performance may occur. On the other hand, if the content of the branched polymer structure exceeds 35 wt%, which is too high, the shrinkage ratio can be implemented high, but the drop impact strength and mechanical strength deteriorate, and problems may occur in using the polyethylene copolymer for actual industrial packaging, etc. Specifically, the content of the branched polymer structure in the polyethylene copolymer may be 26 wt% to 34 wt%, and more specifically, 28 wt% to 32 wt%.

According to one embodiment of the present invention, a polyethylene copolymer simultaneously satisfies the content of the branched polymer structure as described above under the conditions of satisfying the ranges of the density and melt index described above, thereby greatly increasing the shrinkage behavior according to the blow up ratio (BUR) during blown film processing, and exhibits a large shrinkage ratio even at a low temperature of about 140 ^o C or less without increasing the temperature to a high temperature, thereby exhibiting excellent heat shrinkage packaging processability.

In addition, in the above polyethylene copolymer, the weight average molecular weight of the main chain in the branched polymer structure may be 180,000 g/mol to 200,000 g/mol, more specifically 180,000 g/mol to 195,000 g/mol, and even more specifically 185,000 g/mol to 190,000 g/mol.

When comparing polyethylene copolymers having the same weight average molecular weight, by optimizing the content of the branched polymer structure, i.e., the comb-shaped polymer structure, in the polyethylene copolymer and optimizing the molecular weight or number of long side chains in the structure, the shrinkage ratio in the TD direction increases according to the BUR, so that the processing performance as a heat shrinkage film can be significantly improved.

For example, the polyethylene copolymer may have a number of long chain branches (LCBs) of 0.03 to 0.06 per 1,000 carbon atoms in the polyethylene copolymer, and the weight average molecular weight of the long chain branches (LCBs) may be 20,000 to 30,000 g/mol.

In addition, a polyethylene copolymer satisfying the characteristics of the above-mentioned structural parameters can exhibit melting index and molecular weight characteristics comparable to those of conventional linear low-density polyethylene while maintaining excellent mechanical properties.

The above polyethylene copolymer corresponds to a medium-density polyethylene resin having improved shrinkage characteristics in the TD direction in a low-temperature heat shrinkage process, and specifically, has a density measured according to the American Society for Testing and Materials standard ASTM D 1505 of 0.926 g/cm ³ to 0.938 g/cm ³ , more specifically, 0.928 g/cm ³ to 0.935 g/cm ³ .

In addition, the polyethylene copolymer may have a melt index (MI) of 0.23 g/10 ^min to 0.45 g/10 min, specifically 0.25 g/10 min to 0.4 g/10 min, and more specifically 0.28 g/10 min to 0.4 g/10 min, as measured under a temperature of 190 o C and a load of 2.16 kg according to the American Society for Testing and Materials ASTM D 1238 standard.

And, the polyethylene copolymer may have a weight average molecular weight (Mw) of 90,000 g/mol to 120,000 g/mol, specifically 92,000 to 110,000 g/mol, more specifically 95,000 g/mol to 110,000 g/mol or 95,000 g/mol to 100,000 g/mol. In addition, a molecular weight distribution (Mw/Mn) determined by a ratio (Mw/Mn) of the number average molecular weight (Mn) to the weight average molecular weight (Mw) of the polyethylene copolymer may be 3.0 to 3.5, specifically 3.3 to 3.5, more specifically 3.4 to 3.5.

In the present invention, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are conversion values for standard polystyrene measured using gel permeation chromatography (GPC, gel permeation chromatography, manufactured by Water). However, the weight average molecular weight is not limited thereto and may be measured by other methods known in the technical field to which the present invention belongs.

The above polyethylene copolymer may have at least one of the above-described properties, and may have all of the above-described properties in order to exhibit excellent mechanical strength. In this way, when the content and density of the branched polymer structure, and the melt index conditions are satisfied, and the molecular weight of the above-described branched polymer structure and the range of the weight average molecular weight and the molecular weight distribution of the polyethylene copolymer are further satisfied, the shrinkage behavior according to BUR is increased during blown film processing, and the shrinkage ratio in the transverse direction (TD) of the resin flow is improved even at a low temperature of about 140 ^o C or less, or about 120 ^o C to about 140 ^o C, or about 135 ^o C or less, or about 125 ^o C to about 135 ^o C, or about 130 ^o C or so without increasing the temperature to a high temperature, thereby further improving the heat shrinkage packaging performance.

A polyethylene copolymer exhibiting these properties may be, for example, a copolymer of ethylene and an alpha-olefin.

At this time, the alpha olefin may include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, and mixtures thereof. Among these, the polyethylene copolymer may be a copolymer of ethylene and 1-hexene.

If the polyethylene copolymer is the copolymer described above, the above-described properties can be more easily implemented. However, the type of the polyethylene copolymer is not limited to the above-described type, and various types known in the technical field to which the present invention belongs can be provided as long as they can exhibit the above-described properties.

Meanwhile, a polyethylene copolymer having the above-mentioned physical properties may be manufactured in the presence of a metallocene catalyst.

Specifically, the metallocene catalyst may be a hybrid supported metallocene catalyst including at least one first metallocene compound selected from compounds represented by the following chemical formula 1; at least one second metallocene compound selected from compounds represented by the following chemical formula 2; and a carrier supporting the first and second metallocene compounds.

[Chemical Formula 1]

In the above chemical formula 1,

M ¹ is a group 4 transition metal;

A is carbon (C), silicon (Si), or germanium (Ge);

X ¹ and X ² are the same or different, and are each independently a halogen, a nitro group, an amido group, a phosphine group, a phosphide group, a hydrocarbyl group having 1 to 30 carbon atoms, a hydrocarbyloxy group having 1 to 30 carbon atoms, a hydrocarbyloxyhydrocarbyl group having 2 to 30 carbon atoms, -SiH ₃ , a hydrocarbyl(oxy)silyl group having 1 to 30 carbon atoms, a sulfonate group having 1 to 30 carbon atoms, or a sulfone group having 1 to 30 carbon atoms;

R ¹ and R ³ to R ¹⁰ are the same or different, and are each independently hydrogen, a hydrocarbyl group having 1 to 30 carbon atoms, a hydrocarbyloxy group having 1 to 30 carbon atoms, or a hydrocarbyloxyhydrocarbyl group having 2 to 30 carbon atoms;

R ² is hydrogen, a hydrocarbyl group having 1 to 30 carbon atoms, a hydrocarbyloxy group having 1 to 30 carbon atoms, a hydrocarbyloxyhydrocarbyl group having 2 to 30 carbon atoms, a hydrocarbyl(oxy)silyl group having 1 to 20 carbon atoms, or a silylhydrocarbyl group having 1 to 20 carbon atoms;

Q ¹ and Q ² are the same or different, and each independently represents a hydrocarbyl group having 1 to 30 carbon atoms, or a hydrocarbyloxy group having 1 to 30 carbon atoms;

[Chemical formula 2]

In the above chemical formula 2,

M ² is a group 4 transition metal;

X ³ and X ⁴ are the same or different, and are each independently a halogen, a nitro group, an amido group, a phosphine group, a phosphide group, a hydrocarbyl group having 1 to 30 carbon atoms, a hydrocarbyloxy group having 1 to 30 carbon atoms, a hydrocarbyloxyhydrocarbyl group having 2 to 30 carbon atoms, -SiH ₃ , a hydrocarbyl(oxy)silyl group having 1 to 30 carbon atoms, a sulfonate group having 1 to 30 carbon atoms, or a sulfone group having 1 to 30 carbon atoms;

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

R _a is any one of hydrogen, 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;

또는

이고,T is

or

And,

T ¹ is C, Si, Ge, Sn or Pb,

Q ³ is any one of hydrogen, a hydrocarbyl group having 1 to 30 carbon atoms, a hydrocarbyloxy group having 1 to 30 carbon atoms, a hydrocarbyloxyhydrocarbyl group having 2 to 30 carbon atoms, -SiH ₃ , a hydrocarbyl(oxy)silyl group having 1 to 30 carbon atoms, a hydrocarbyl group having 1 to 30 carbon atoms substituted with a halogen, and -NR _b R _c ,

Q ⁴ is any one of hydrocarbyloxyhydrocarbyl groups having 2 to 30 carbon atoms,

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

C ¹ is any one of the ligands represented by the following chemical formulas 2a to 2d,

[Chemical formula 2a]

[Chemical formula 2b]

[Chemical formula 2c]

[chemical formula 2d]

In the above chemical formulas 2a to 2d,

Y is O or S,

R ¹¹ to R ¹⁶ are the same or different, and each independently represent hydrogen, a hydrocarbyl group having 1 to 30 carbon atoms, or a hydrocarbyloxy group having 1 to 30 carbon atoms.

Unless otherwise specified in this specification, the following terms may be defined as follows:

A hydrocarbyl group is a monovalent functional group in which a hydrogen atom is removed from a hydrocarbon, and may include an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, an aralkenyl group, an aralkynyl group, an alkylaryl group, an alkenylaryl group, and an alkynylaryl group. In addition, the hydrocarbyl group having 1 to 30 carbon atoms may be a hydrocarbyl group having 1 to 20 carbon atoms or 1 to 10 carbon atoms. For example, the hydrocarbyl group may be a straight-chain, branched-chain, or cyclic alkyl. More specifically, the hydrocarbyl group having 1 to 30 carbon atoms may be a straight-chain, branched-chain or cyclic alkyl group such as a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, a cyclohexyl group, or the like; or an aryl group such as phenyl, biphenyl, naphthyl, anthracenyl, phenanthrenyl, or fluorenyl. In addition, it may be an alkylaryl such as methylphenyl, ethylphenyl, methylbiphenyl, or methylnaphthyl, and may also be an arylalkyl such as phenylmethyl, phenylethyl, biphenylmethyl, or naphthylmethyl. In addition, it may be an alkenyl such as allyl, allyl, ethenyl, propenyl, butenyl, or pentenyl.

The hydrocarbyloxy group is a functional group in which a hydrocarbyl group is bonded to oxygen. Specifically, the hydrocarbyloxy group having 1 to 30 carbon atoms may be a hydrocarbyloxy group having 1 to 20 carbon atoms or 1 to 10 carbon atoms. For example, the hydrocarbyloxy group may be a linear, branched, or cyclic alkyl. More specifically, the hydrocarbyloxy group having 1 to 30 carbon atoms may be a linear, branched, or cyclic alkoxy group such as a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, an iso-butoxy group, a tert-butoxy group, an n-pentoxy group, an n-hectoxy group, an n-heptoxy group, or a cyclohectoxy group; or an aryloxy group such as a phenoxy group or a naphthalenoxy group.

A hydrocarbyloxyhydrocarbyl group is a functional group in which at least one hydrogen atom of a hydrocarbyl group is replaced by at least one hydrocarbyloxy group. Specifically, the 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 a linear, branched, or cyclic alkyl. More specifically, the hydrocarbyloxyhydrocarbyl group having 2 to 30 carbon atoms may be an alkoxyalkyl group such as a methoxymethyl group, a methoxyethyl group, an ethoxymethyl group, an iso-propoxymethyl group, an iso-propoxyethyl group, an iso-propoxyhexyl group, a tert-butoxymethyl group, a tert-butoxyethyl group, or a tert-butoxyhexyl group; Or it may be an aryloxyalkyl group such as a phenoxyhexyl group.

A hydrocarbyl(oxy)silyl group is a functional group in which 1 to 3 hydrogens of _-SiH3 are replaced by 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 selected from the group consisting of an alkylsilyl group such as a methylsilyl group, a dimethylsilyl group, a trimethylsilyl group, a dimethylethylsilyl group, a diethylmethylsilyl group, or a dimethylpropylsilyl group; an alkoxysilyl group such as a methoxysilyl group, a dimethoxysilyl group, a trimethoxysilyl group, or a dimethoxyethoxysilyl group; It may be an alkoxyalkylsilyl group such as a methoxydimethylsilyl group, a diethoxymethylsilyl group, or a dimethoxypropylsilyl group.

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

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

The sulfonate group has a structure of -O-SO ₂ -R ^a , where R ^a can be a hydrocarbyl group having 1 to 30 carbon atoms. Specifically, the sulfonate group having 1 to 30 carbon atoms can be a methanesulfonate group or a phenylsulfonate group.

A sulfone group having 1 to 30 carbon atoms has a structure of -R ^c' -SO ₂ -R ^c" , wherein R ^c' and R ^c" are the same or different and can each independently be any one of a hydrocarbyl group having 1 to 30 carbon atoms. Specifically, the sulfone group having 1 to 30 carbon atoms can be a methylsulfonylmethyl group, a methylsulfonylpropyl group, a methylsulfonylbutyl group, or a phenylsulfonylpropyl group.

In the present specification, when two adjacent substituents are linked to each other to form an aliphatic or aromatic ring, it means that the atom(s) of the two substituents and the atom(s) to which the two substituents are bonded are linked to each other to form a ring. Specifically, an example in which R _a and R _b or R _a' and R _b ' of -NR _a R _b or -NR _a' R _b' are linked to each other to form an aliphatic ring may include a piperidinyl group and the like, and an example in which R _a and R _b or R _a' and R _b' of -NR _a R _b or -NR _a' R _b' are linked to each other to form an aromatic ring may include a pyrrolyl group and the like.

And, the group 4 transition metal may be titanium (Ti), zirconium (Zr), hafnium (Hf), or rutherfordium (Rf), specifically titanium (Ti), zirconium (Zr), or hafnium (Hf), more specifically zirconium (Zr) or hafnium (Hf), but is not limited thereto.

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

The above-described substituents may be arbitrarily substituted with one or more substituents selected from the group consisting of a hydroxy group; a halogen; a hydrocarbyl group; a hydrocarbyloxy group; a hydrocarbyl group or hydrocarbyloxy group containing at least one heteroatom from groups 14 to 16; a silyl group; a hydrocarbyl(oxy)silyl group; a phosphine group; a phosphide group; a sulfonate group; and a sulfone group, within a range that exhibits the same or similar effect as the desired effect.

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

Meanwhile, the hybrid supported catalyst exhibits high activity along with excellent process stability in ethylene polymerization by supporting a first metallocene compound having the characteristic of increasing the long chain branch (LCB) content during ethylene polymerization and a second metallocene compound having the characteristic of increasing the short chain branch (SCB) content, and has useful characteristics in producing a polyethylene copolymer having excellent mechanical properties as well as excellent shrinkage and processability through improvement in molecular structure and change in distribution.

In particular, in the hybrid supported metallocene catalyst according to the above embodiment, the first metallocene compound represented by the chemical formula 1 may contribute to improving the mechanical properties through improving the molecular structure and changing the distribution by increasing the long chain branch (LCB) content, and the second metallocene compound represented by the chemical formula 2 may contribute to improving the shrinkage ratio and processability by increasing the short chain branch (SCB) content. The hybrid supported metallocene catalyst may exhibit excellent support performance, catalytic activity, and high copolymerizability by using the first metallocene compound having a low copolymerizability and the second metallocene compound having a high copolymerizability together as a hybrid catalyst.

Specifically, the first metallocene compound may be represented by the following chemical formula 1-1.

[Chemical Formula 1-1]

In the above chemical formula 1-1, M ¹ , X ¹ , X ² , R ² , R ⁷ to R ¹⁰ , Q ¹ , and Q ² are as defined in the above chemical formula 1.

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

And, in the chemical formula 1, A may be silicon (Si).

And, in the chemical formula 1, X ¹ and X ² can each be a halogen, and specifically, can be chlorine.

And, in the chemical formula 1, R ¹ and R ³ to R ⁶ are each hydrogen, and R ² can be hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, an arylalkyl group having 7 to 14 carbon atoms, an alkylaryl group having 7 to 14 carbon atoms, an alkylsilyl group having 1 to 10 carbon atoms, a silylalkyl group having 1 to 10 carbon atoms, or an alkylsilylalkylene group having 2 to 12 carbon atoms. Specifically, R ¹ and R ³ to R ⁶ are each hydrogen, and R ² can be hydrogen, methyl, ethyl, propyl, butyl, butenyl, trimethylsilylmethyl, or phenyl.

And, in the chemical formula 1, R ⁷ to R ¹⁰ may each be an alkyl group having 1 to 20 carbon atoms, specifically an alkyl group having 1 to 3 carbon atoms, and more specifically, may be methyl.

And, in the chemical formula 1, Q ¹ and Q ² may each be an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 12 carbon atoms, specifically, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and more specifically, may be methyl, ethyl, or phenyl.

And, the first metallocene compound may be represented by one of the following structural formulas.

The first metallocene compound represented by the above structural formulas can be synthesized by applying known reactions, and more detailed synthetic methods can be found in the Examples.

Meanwhile, in the method for producing the metallocene compound, hybrid supported catalyst, or catalyst composition of the present invention, equivalent (eq) means molar equivalent (eq/mol).

In the present invention, the first metallocene compound may be a meso isomer, a racemic isomer, or a mixed form thereof.

As used herein, the term "racemic form" or "racemic isomer" or "racemic isomer" means a form in which identical substituents on two cyclopentadienyl moieties are on opposite planes with respect to the center of the cyclopentadienyl moieties and a transition metal, such as zirconium (Zr) or hafnium (Hf), represented by M ₁ or M ₂ in the chemical formula 1 or 2.

And, the term "meso isomer" or "meso isomer" in the present specification means a stereoisomer of the racemic isomer described above, in which the same substituents on the two cyclopentadienyl moieties are in the same phase with respect to the plane including the transition metal represented by M ₁ or M ₂ in the chemical formula 1 or 2, such as zirconium (Zr) or hafnium (Hf), and the center of the cyclopentadienyl moiety.

Meanwhile, the hybrid supported catalyst is characterized by including a second metallocene compound represented by the chemical formula 2 together with the first metallocene compound described above.

Specifically, in the chemical formula 2, Z is -NR _a -, and R _a may be a hydrocarbyl group having 1 to 10 carbon atoms, and specifically, R _a may be a straight-chain or branched alkyl group having 1 to 6 carbon atoms, and more specifically, may be a tert-butyl group.

이고, T¹은 탄소(C) 또는 실리콘(Si)이며, Q³은 탄소수 1 내지 30의 하이드로카빌기, 또는 탄소수 1 내지 30의 하이드로카빌옥시기이고, Q⁴는 탄소수 2 내지 30의 하이드로카빌옥시하이드로카빌기일 수 있다. 구체적으로, Q³은 탄소수 1 내지 10의 하이드로카빌기이고, Q⁴는 탄소수 2 내지 12의 하이드로카빌옥시하이드로카빌기일 수 있으며, 좀더 구체적으로 Q³은 탄소수 1 내지 6의 알킬기이고, Q⁴는 탄소수 1 내지 6의 알콕시 치환된 탄소수 1 내지 6의 알킬기일 수 있다. 보다 구체적으로, T¹은 실리콘(Si)이며, Q³은 메틸이고, Q⁴는 tert-부톡시 치환된 헥실일 수 있다.And, in the chemical formula 2, T is

, T ¹ is carbon (C) or silicon (Si), Q ³ is a hydrocarbyl group having 1 to 30 carbon atoms, or a hydrocarbyloxy group having 1 to 30 carbon atoms, and Q ⁴ may be a hydrocarbyloxyhydrocarbyl group having 2 to 30 carbon atoms. Specifically, Q ³ may be a hydrocarbyl group having 1 to 10 carbon atoms, Q ⁴ may be a hydrocarbyloxyhydrocarbyl group having 2 to 12 carbon atoms, and more specifically, Q ³ may be an alkyl group having 1 to 6 carbon atoms, and Q ⁴ may be an alkoxy-substituted alkyl group having 1 to 6 carbon atoms. More specifically, T ¹ may be silicon (Si), Q ³ may be methyl, and Q ⁴ may be tert-butoxy-substituted hexyl.

Specifically, the second metallocene compound may be represented by any one of the following chemical formulas 2-1 to 2-4.

[Chemical Formula 2-1]

[Chemical Formula 2-2]

[Chemical Formula 2-3]

[Chemical Formula 2-4]

In the above chemical formulas 2-1 to 2-4, M ² , X ³ , X ⁴ , R _a , T ¹ , Q ³ , Q ⁴ , and R ¹¹ to R ¹⁶ are as defined in the above chemical formula 2.

And, in the chemical formula 2, R ¹¹ to R ¹⁴ are each hydrogen or a hydrocarbyl group having 1 to 10 carbon atoms, and R ¹⁵ and R ¹⁶ can each be a hydrocarbyl group having 1 to 10 carbon atoms. Specifically, R ¹¹ to R ¹⁴ are each hydrogen or an alkyl having 1 to 10 carbon atoms.

R ¹⁵ and R ¹⁶ may each be an alkyl having 1 to 10 carbon atoms. More specifically, R ¹¹ to R ¹⁴ may each be hydrogen or methyl, and R ¹⁵ and R ¹⁶ may be methyl.

And, in the chemical formula 2, M ² may be titanium (Ti), zirconium (Zr), or hafnium (Hf), and preferably titanium (Ti).

And, in the chemical formula 2, X ¹ and X ² may each be a halogen or an alkyl group having 1 to 10 carbon atoms or an alkyl group having 1 to 6 carbon atoms, and specifically, may be chlorine or methyl.

And, in the chemical formula 2, the second metallocene compound may be represented by one of the following structural formulas.

The second metallocene compound represented by the above structural formulas can be synthesized by applying known reactions, and more detailed synthetic methods can be referred to the examples and synthetic examples described below.

Meanwhile, in the hybrid supported metallocene catalyst of the present invention, the first metallocene compound and the second metallocene compound may be supported at a molar ratio of 1:2 to 5:1. By including the first and second metallocene compounds at the above-mentioned mixed molar ratio, excellent support performance, catalytic activity, and high copolymerizability can be exhibited. In particular, if the support ratio is less than 1:2, only the first metallocene compound plays a dominant role, making it difficult to reproduce the molecular structure of the desired polymer and causing deterioration in mechanical properties. In addition, if the support ratio exceeds 5:1, only the second metallocene compound plays a dominant role, causing deterioration in processability and shrinkage rate.

Specifically, a hybrid supported metallocene catalyst in which the first metallocene compound and the second metallocene compound are supported in a molar ratio of 1:1.5 to 3:1, or a molar ratio of 1:1 to 2:1, exhibits high activity in ethylene polymerization, excellent copolymerizability, excellent mechanical properties, and is preferable for producing polyethylene having improved processability and shrinkage.

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 as well as the processability and shrinkage ratio can all be further improved due to the interaction of two or more catalysts.

In the hybrid supported metallocene catalyst of the present invention, a carrier containing a hydroxyl group on a surface may be used as a carrier for supporting the first metallocene compound and the second metallocene compound, and preferably, it may be a carrier containing a highly reactive hydroxyl group and a siloxane group on the surface, which is dried to remove moisture from the surface.

For example, silica, silica-alumina, and silica-magnesia dried at high temperatures can be used, and these can typically contain oxide, carbonate, sulfate, and nitrate components such as Na ₂ O, K ₂ CO ₃ , BaSO ₄ , and Mg(NO ₃ ) ₂ .

The drying temperature of the carrier is preferably about 200 ^o C to about 800 ^o C, more preferably about 300 ^o C to about 600 ^o C, and most preferably about 300 ^o C to about 400 ^o C. If the drying temperature of the carrier is less than 200 ^o C, the moisture content is too high, causing the moisture on the surface to react with the cocatalyst described below, and if it exceeds 800 ^o C, the pores on the surface of the carrier merge, reducing the surface area, and also, since many hydroxyl groups on the surface disappear and only siloxane groups remain, the reaction sites with the cocatalyst decrease, which is not preferable.

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

If the amount of the above hydroxyl group is less than about 0.1 mmol/g, there are few reaction sites with the cocatalyst, and if it exceeds about 10 mmol/g, it is not preferable because there is a possibility that it is caused by moisture other than the hydroxyl group present on the surface of the carrier particle.

For example, the total amount of the first and second metallocene compounds supported on the carrier such as silica, i.e., the supported amount of the metallocene compound, may be 0.01 mmol/g to 1 mmol/g based on 1 g of the carrier. That is, it is preferable to control the supported amount to fall within the aforementioned range in consideration of the contribution effect of the catalyst by the metallocene compound.

Meanwhile, the hybrid supported metallocene catalyst may be one in which at least one of the first metallocene compounds and at least one of the second metallocene compounds are supported on a carrier together with a cocatalyst compound. Any cocatalyst used when polymerizing olefins under a general metallocene catalyst may be used as the cocatalyst. Such a cocatalyst causes a bond to be formed between a hydroxyl group on the carrier and a Group 13 transition metal. In addition, since the cocatalyst exists only on the surface of the carrier, it can contribute to securing the unique characteristics of the specific hybrid catalyst composition of the present disclosure without a fouling phenomenon in which the polymer particles stick to the reactor wall or each other.

In addition, the hybrid supported metallocene catalyst of the present invention may further include at least one cocatalyst selected from the group consisting of compounds represented by the following chemical formulas 3 to 5.

[Chemical Formula 3]

-[Al(R ³¹ )-O] _c -

In the above chemical formula 3,

R ³¹ is each independently halogen, C _1-20 alkyl or C _1-20 haloalkyl,

c is an integer greater than or equal to 2,

[Chemical Formula 4]

D(R ⁴¹ ) ₃

In the above chemical formula 4,

D is aluminum or boron,

R ⁴¹ is each independently hydrogen, halogen, C _1-20 hydrocarbyl or C _1-20 hydrocarbyl substituted with halogen,

[Chemical Formula 5]

[LH] ⁺ [Q(E) ₄ ] ^- or [L] ⁺ [Q(E) ₄ ] ^-

In the above chemical formula 5,

L is a neutral or cationic Lewis base,

[LH] ⁺ is Bronsted acid,

Q is Br ³⁺ or Al ³⁺ ,

E is each independently C _6-40 aryl or C _1-20 alkyl, wherein said C _6-40 aryl or C _1-20 alkyl is unsubstituted or substituted with one or more substituents selected from the group consisting of halogen, C _1-20 alkyl, C _1-20 alkoxy, and C _6-40 aryloxy.

The compound represented by the above chemical formula 3 may be an alkylaluminoxane, such as modified methylaluminoxane (MMAO), methylaluminoxane (MAO), ethylaluminoxane, isobutylaluminoxane, butylaluminoxane, etc.

The alkyl metal compound represented by the above chemical formula 4 may be, for example, trimethylaluminum, triethylaluminum, triisobutylaluminum, tripropylaluminum, tributylaluminum, dimethylchloroaluminum, dimethylisobutylaluminum, dimethylethylaluminum, diethylchloroaluminum, triisopropylaluminum, tri-s-butylaluminum, tricyclopentylaluminum, tripentylaluminum, triisopentylaluminum, trihexylaluminum, ethyldimethylaluminum, methyldiethylaluminum, triphenylaluminum, tri-p-tolylaluminum, dimethylaluminum methoxide, dimethylaluminum ethoxide, trimethylboron, triethylboron, triisobutylboron, tripropylboron, tributylboron, and the like.

The compound represented by the above chemical formula 5 is, for example, triethylammonium tetraphenylboron, tributylammonium tetraphenylboron, trimethylammonium tetraphenylboron, tripropylammonium tetraphenylboron, trimethylammonium tetra(p-tolyl)boron, tripropylammonium tetra(p-tolyl)boron, triethylammonium tetra(o,p-dimethylphenyl)boron, trimethylammonium tetra(o,p-dimethylphenyl)boron, tributylammonium tetra(p-trifluoromethylphenyl)boron, trimethylammonium tetra(p-trifluoromethylphenyl)boron, tributylammonium tetrapentafluorophenylboron, N,N-diethylanilinium tetraphenylboron, N,N-diethylanilinium tetrapentafluorophenylboron, diethylammonium tetrapentafluorophenylboron, triphenylphosphonium tetraphenylboron, Trimethylphosphonium tetraphenylboron, triethylammonium tetraphenylaluminum, tributylammonium tetraphenylaluminum, trimethylammonium tetraphenylaluminum, tripropylammonium tetraphenylaluminum, trimethylammonium tetra(p-tolyl)aluminum, tripropylammonium tetra(p-tolyl)aluminum, triethylammonium tetra(o,p-dimethylphenyl)aluminum, tributylammonium tetra(p-trifluoromethylphenyl)aluminum, trimethylammonium tetra(p-trifluoromethylphenyl)aluminum, tributylammonium tetrapentafluorophenylaluminum, N,N-diethylanilinium tetraphenylaluminum, N,N-diethylanilinium tetrapentafluorophenylaluminum, diethylammonium tetrapentafluorophenylaluminum, It may be triphenylphosphoniumtetraphenylaluminum, trimethylphosphoniumtetraphenylaluminum, triphenylcarboniumtetraphenylboron, triphenylcarboniumtetraphenylaluminum, triphenylcarboniumtetra(p-trifluoromethylphenyl)boron, triphenylcarboniumtetrapentafluorophenylboron, etc.

In addition, the hybrid supported metallocene catalyst may include the cocatalyst and the first metallocene compound in a molar ratio of about 1:1 to about 1:10000, preferably in a molar ratio of about 1:1 to about 1:1000, and more preferably in a molar ratio of about 1:10 to about 1:100.

In addition, the hybrid supported metallocene catalyst may also include the cocatalyst and the second metallocene compound in a molar ratio of about 1:1 to about 1:10000, preferably in a molar ratio of about 1:1 to about 1:1000, and more preferably in a molar ratio of about 1:10 to about 1:100.

At this time, if the molar ratio is less than about 1, the metal content of the cocatalyst is too low, so that the catalytic active species is not well formed, which may lower the activity, and if the molar ratio exceeds about 10,000, there is a concern that the metal of the cocatalyst may act as a catalyst poison.

The amount of such a cocatalyst supported may be about 5 mmol to about 20 mmol based on 1 g of the carrier.

Meanwhile, the hybrid supported metallocene catalyst can be produced by a production method including a step of supporting a promoter on a carrier; a step of supporting a first metallocene compound on the carrier supporting the promoter; and a step of supporting a second metallocene compound on the carrier supporting the promoter and the first metallocene compound.

Alternatively, the hybrid supported metallocene catalyst can be produced by a production method including the steps of: supporting a promoter on a carrier; supporting a second metallocene compound on the carrier supported with the promoter; and supporting a first metallocene compound on the carrier supported with the promoter and the second metallocene compound.

Alternatively, the hybrid supported metallocene catalyst can be produced by a production method including the steps of: supporting a first metallocene compound on a carrier; supporting a cocatalyst on the carrier supporting the first metallocene compound; and supporting a second metallocene compound on the carrier supporting the cocatalyst and the first metallocene compound.

In the above method, the supporting conditions are not particularly limited and can be performed within a range well known to those skilled in the art. For example, high-temperature supporting and low-temperature supporting can be appropriately used, and for example, the supporting temperature can be in a range of about -30 ^o C to about 150 ^o C, and preferably about 50 ^o C to about 98 ^o C, or about 55 ^o C to about 95 ^o C. The supporting time can be appropriately adjusted depending on the amount of the first metallocene compound to be supported. The reacted supported catalyst can be used as it is by removing the reaction solvent by filtering or distilling under reduced pressure, and if necessary, it can be used by performing a Soxhlet filter with an aromatic hydrocarbon such as toluene.

And, the production of the supported catalyst can be performed under a solvent or without a solvent. When a solvent is used, usable solvents include aliphatic hydrocarbon solvents such as hexane or pentane, aromatic hydrocarbon solvents such as toluene or benzene, hydrocarbon solvents substituted with chlorine atoms such as dichloromethane, ether solvents such as diethyl ether or tetrahydrofuran (THF), acetone, ethyl acetate, and most organic solvents, with hexane, heptane, toluene, or dichloromethane being preferred.

Meanwhile, a polyethylene copolymer as described above can be produced through a method including a step of 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 copolymerizability, and can produce a polyethylene copolymer capable of producing a blown film having excellent heat shrinkage packaging performance in the TD direction even at low temperatures.

The method for producing the above polyethylene copolymer can be carried out by a slurry polymerization method using ethylene and alpha-olefin as raw materials in the presence of the above-described hybrid supported catalyst, applying a conventional device and contact technique.

The method for producing the above polyethylene copolymer can copolymerize ethylene and alpha-olefin using a continuous slurry polymerization reactor, a loop slurry reactor, etc., but is not limited thereto.

Here, the alpha-olefin is as described above, and for example, 1-hexene can be used as the alpha-olefin. Accordingly, in the slurry polymerization, a polyethylene copolymer capable of producing a blown film having excellent heat shrinkage packaging performance in the TD direction even at low temperatures can be produced by polymerizing the ethylene and 1-hexene.

And, the polymerization temperature can be about 25 ^o C to about 500 ^o C, or about 25 ^o C to about 300 ^o C, or about 30 ^o C to about 200 ^o C, or about 50 ^o C to about 150 ^o C, or about 60 ^o C to about 120 ^o C. In addition, the polymerization pressure can be about 1 kgf/㎠ to about 100 kgf/㎠, or about 1 kgf/㎠ to about 50 kgf/㎠, or about 5 kgf/㎠ to about 45 kgf/㎠, or about 10 kgf/㎠ to about 40 kgf/㎠, or about 15 kgf/㎠ to about 35 kgf/㎠.

In the copolymerization step, the supported metallocene catalyst described above can be dissolved or diluted in a C5 to C12 aliphatic hydrocarbon solvent, such as pentane, hexane, heptane, nonane, decane, and isomers thereof; an aromatic hydrocarbon solvent such as toluene and benzene; a hydrocarbon solvent substituted with a chlorine atom such as dichloromethane and chlorobenzene; and the like. It is preferable to use the solvent used here after removing a small amount of water or air, which act as catalyst poisons, by treating it with a small amount of alkyl aluminum, and it is also possible to perform the process using a cocatalyst.

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

By the above-described manufacturing method, a polyethylene copolymer having the above-described physical properties can be manufactured.

The polyethylene copolymer having the above-mentioned physical properties has excellent processability when manufacturing a film due to its processing load characteristics, and also has excellent transparency. Accordingly, it can be usefully applied to various fields requiring excellent transparency and processability. In particular, the polyethylene copolymer can stably form a blown film by a melt-blown method, etc.

Meanwhile, the blown film can be manufactured by a conventional film manufacturing method, except that the above-mentioned polyethylene copolymer is used.

For example, when processing the blown film, the polyethylene copolymer can be manufactured by inflation molding using an extruder to a predetermined thickness, specifically, 30 micrometers (㎛) to 90 micrometers (㎛). At this time, the extrusion temperature of the extruder can be 160 ^o C to 200 ^o C. In addition, the blow up ratio (BUR) can be 3.4 or less, more specifically, 2.3 to 3.4.

In addition, the polyethylene blown film according to the present invention may further contain additives well known in this field in addition to the above-mentioned polyethylene copolymer. Specifically, such 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 types of the additives are not particularly limited, and general additives known in the art can be used.

The polyethylene blown film according to one embodiment of the present invention manufactured by the above method can significantly increase shrinkage behavior according to BUR and improve shrinkage ratio in the TD direction, thereby improving heat shrinkage packaging performance.

For example, the blown film may have a shrinkage in the transverse direction (TD) of 10% to 15%, or 11% to 15%, or 11.5% to 15%, when measured at 130 ^° C. for a film formed with a film thickness of 60 micrometers (㎛) at a blow up ratio (BUR) of 2.3, and may have a shrinkage in the transverse direction (TD) of 20% or more, or 20% to 25%, or 21% or more, or 21% to 25%, or 23% or more, or 23% to 25%, when measured at 130 ^° C. for a film formed with a film thickness of 60 micrometers (㎛) at a blow up ratio (BUR) of 3.0.

The above blown film is a product having excellent film processability and transparency, and excellent mechanical properties such as tensile strength, elongation, and impact strength, and can be effectively used in the production of heavy-duty films, lamination films, and general industrial blown films. Among these films, heat shrinkable films are applied to industrial packaging, food, beverage, and general product packaging. In particular, the blown film according to the present invention has excellent packaging performance due to the shrinkage rate in the TD direction, and can obtain a downgauging effect due to recent environmental issues ( _CO2 reduction) and cost reduction.

The polyethylene according to the present invention has an excellent effect of being able to produce a blown film having excellent heat shrinkage packaging performance due to a large shrinkage rate in the transverse direction (TD) of the resin flow even at low temperatures without increasing the temperature to high temperatures.

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

[Example]

<Preparation of the first metallocene compound>

Synthesis Example 1

Tetramethylcyclopentadiene (TMCP) was lithiated with n-butyllithium (n-BuLi, 1 equivalent) in tetrahydrofuran (THF, 0.4 M), filtered, and used as TMCP-Li salts. 3-Phenylindene (3-Ph-Ind) was lithiated with n-BuLi (1 equivalent) in hexane (0.5 M), filtered, and used as 3-Ph-Ind-Li salts. 50 mmol of TMCP-Li salts and 100 mL of THF were added to a 250 mL Schlenk flask under Ar. 1 equivalent of (CH ₃ ) ₂ SiCl ₂ was added at -20 ^o C. After 6 h, 3 mol% CuCN and 3-Ph-Ind-Li salts (50 mmol, MTBE 1 M solution) were added at -20 ^o C and reacted for 12 h. The organic layer was separated with water and hexane to obtain the ligand.

The synthesized ligand (50 mmol) above was dissolved in 100 mL of methyl tert-butyl ether (MTBE) under Ar, and 2 equivalents of n-BuLi were added dropwise at -20 degrees Celsius. After 16 hours of reaction, the ligand-Li solution was added to ZrCl ₄ (THF) ₂ (50 mmol, MTBE 1 M solution). After 16 hours of reaction, the solvent was removed, dissolved in methylene chloride (MC), and filtered to remove LiCl. The solvent in the filtrate was removed, and 80 mL of tert -butyl methyl ether (MTBE) was added, stirred for 2 hours, and filtered to obtain a solid catalyst precursor (Yield 40%).

¹ H NMR (500 MHz, C ₆ D ₆ ): 0.78 (3H, s), 0.97 (3H, s), 1.64 (3H, s), 1.84 (3H, s), 1.88 (6H, 2s), 5.91 ( 1H, s), 6.89 (1H, t), 7.19 (1H, t), 7.25 (1H, t), 7.30 (2H, t), 7.37 (1H, d), 7.74 (2H, d), 7.93 (1H) , d).

Comparative synthesis example 1

TMCP-Li (1.3 g, 10 mmol), CuCN (45 mg, 5 mol%), and THF (10 mL) were added to a dried 250 mL schlenk flask. Then, the temperature of the flask was cooled to below -20 ^o C, dichlorodiphenylsilane (2.5 g, 10 mmol) was added dropwise, and the resulting mixture was stirred at room temperature (RT, approximately 22–25 ^o C) for 16 hours. Then, the temperature of the flask was cooled to below -20 ^o C, indene-lithiation solution (1.2 g, 10 mmol in 10 mL of THF) was added dropwise, and the resulting mixture was stirred at room temperature for 24 hours. Thereafter, the resulting solution was dried under reduced pressure to remove the solvent from the solution. And, the obtained solid was dissolved in hexane, filtered to remove the remaining LiCl, and the filtrate was dried under reduced pressure to remove hexane from the filtrate, thereby obtaining diphenyl(indenyl)(tetramethylcyclopentadienyl)silane. In a 100 mL schlenk flask, previously synthesized diphenyl(indenyl)(tetramethylcyclopentadienyl)silane (4.2 g, 10 mmol) was dissolved in THF (15 mL). And, after this solution was cooled to -20℃ or lower, n-BuLi (2.5 M in hexane, 8.4 mL, 21 mmol) was slowly added dropwise to the solution, and the obtained solution was stirred at room temperature for 6 hours.

Meanwhile, ZrCl ₄ (THF) ₂ (3.8 g, 10 mmol) was dispersed in toluene (15 mL) in a separately prepared 250 mL schlenk flask, and the resulting mixture was stirred at -20 ^o C. Then, the previously prepared lithiated ligand solution was slowly injected into the mixture. Then, the resulting mixture was stirred at room temperature for 48 hours. Thereafter, the resulting solution was dried under reduced pressure to remove the solvent from the solution. Then, the resulting solid was dissolved in dichloromethane (DCM), filtered to remove the remaining LiCl, and the filtrate was dried under reduced pressure to remove DCM. Then, the obtained solid was added to 30 mL of toluene, stirred for 16 hours, and filtered to obtain diphenylsilylene(tetramethylcyclopentadienyl)(indenyl)zirconium dichloride (2.1 g, 3.6 mmol) as a lemon-colored solid (36% yield).

^1H NMR (500 MHz, CDCl ₃ ): 8.08-8.12 (2H, m), 7.98-8.05 (2H, m), 7.77 (1H, d), 7.47-7.53 (3H, m), 7.42-7.46 (3H) , m), 7.37-7.41 (2H, m), 6.94 (1H, t), 6.23 (1H, d), 1.98 (3H, s), 1.95 (3H, s), 1.68 (3H, s), 1.52 ( 3H, s).

Diphenylsilylene(tetramethylcyclopentadienyl)(indenyl)-zirconium dichloride (1.0 g, 1.7 mmol), Pd/C (10 mol%), and DCM (40 mL) previously synthesized were introduced into a 100 mL high-pressure reactor, and hydrogen was filled up to a pressure of about 60 bar. Then, the mixture in the high-pressure reactor was stirred at about 80 ^o C for about 24 hours. When the reaction was complete, the reaction product was passed through a celite pad to remove the solid from the reaction product, and diphenylsilylene(tetramethylcyclopentadienyl)(tetrahydroindenyl)zirconium dichloride was obtained (0.65 g, 1.1 mmol, 65% yield).

^1H NMR (500 MHz, CDCl ₃ ): 7.90-8.00 (4H, m), 7.38-7.45 (6H, m), 6.80 (1H, s), 5.71 (1H, s), 3.15-3.50 (1H, m) ), 2.75-2.85 (1H, m), 2.50-2.60 (1H, m), 2.12 (3H, s), 2.03 (3H, s), 1.97-2.07 (1H, m), 1.76 (3H, s), 1.53-1.70 (4H, m), 1.48 (3H, s).

Comparative synthesis example 2

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

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

¹ H-NMR (300 MHz, CDCl ₃ ): 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 ): 135.09, 116.66, 112.28, 72.42, 61.52, 30.66, 30.31, 30.14, 29.18, 27.58, 26.00

<Preparation of a second metallocene compound>

Synthesis Example 2

(1) Synthesis of (E)-1-(4,5-dimethylthiophen-2-yl)-2-methylbut-2-en-1-one

2,3-dimethylthiophene (9.99 g, 89.1 mmol) was weighed in a Schlenk flask, and dissolved in 90 mL of THF. n-BuLi (1.05 eq, 37.4 mL) was added dropwise at -78 ^o C, and the mixture was reacted overnight at room temperature (RT). CuCN (0.5 eq, 4 g) was weighed in another Schlenk flask, THF 30 mL was added, and the temperature was lowered to -78 ^o C, and the reaction solution was transferred. After 2 hours of reaction at RT, tigloyl chloride (1 eq, 9.8 mL) was added dropwise at -78 ^o C. After overnight reaction at RT, the mixture was worked up with aqueous Na ₂ CO ₃ solution and ethyl acetate (EA), and the organic layer was concentrated to obtain a brown liquid product, 15.48 g, in a yield of 89.5%.

¹ H-NMR (in CDCl ₃ , 500 MHz): 7.94 (s, 1H), 7.17-7.16 (m, 1H), 3.04 (s, 3H), 2.81 (s, 3H), 2.59 (s, 3H), 2.53 (d, 3H)

(2) Synthesis of 2,3,4,5-tetramethyl-4,5-dihydro-6H-cyclopenta[b]thiophen-6-one

In a 1 L round bottom flask (one neck), 15.48 g (79.7 mmol) of (E)-1-(4,5-dimethylthiophen-2-yl)-2-methylbut-2-en-1-one obtained above was weighed, 15 mL of chlorobenzene was added, and stirred. After adding 100 mL of sulfuric acid, the mixture was reacted overnight at RT, 800 mL of deionized water (DIW) was added, stirred, transferred to a separate pane, and extracted with EA. The organic layer was washed with an aqueous _{Na2CO3 solution} , concentrated, and 10.66 g of a copper-colored oil product was obtained with a yield of 68.9%.

¹ H-NMR (in CDCl ₃ , 500 MHz): 6.28 (s, 2H), 6.35 (s, 1H), 3.33-3.32 (m, 4H), 2.48 (s, 6H), 2.36 (s, 6H), 1.97 (d, 6H), 1.51 (s, 18H), 1.46-1.26 (m, 20H), 1.18 (m, 18H), 0.49 (s, 3H), 0.46 (s, 3H), 0.31 (s, 6H) , 0.00 (s, 3H), -0.20 (s, 3H)

(3) Synthesis of 2,3,4,5-tetramethyl-6H-cyclopenta[b]thiophene

3 g (15.4 mmol) of 2,3,4,5-tetramethyl-4,5-dihydro-6H-cyclopenta[b]thiophen-6-one obtained above was weighed in a vial, dissolved in 18 mL of THF and 12 mL of methanol (MeOH). Immerse the vial in ice water at 0 ^o C, stir, and add NaBH ₄ (1.5 eq, 876 mg) little by little with a spatula. After overnight reaction at RT, DIW was added, the organic layer was separated and concentrated, and 60 mL of THF and DIW were mixed in a 1:1 ratio, 12 mL of 3N HCl was added, dissolved, and heated at 80 ^o C for 3 hours. Hexane and DIW were added, the organic layer was separated, neutralized with aqueous Na ₂ CO ₃ solution, and concentrated to obtain 2.3 g of a brown liquid product with a yield of 83.5%.

¹ H-NMR (in CDCl ₃ , 500 MHz): 6.28 (s, 2H), 3.15 (m, 1H), 3.05 (m, 1H), 2.37 (s, 6H), 2.16 (s, 6H), 2.16 ( s, 6H), 2.03 (s, 6H), 1.28 (d, 6H)

(4) 1-(6-(tert-butoxy)hexyl)-N-(tert-butyl)-1-methyl-1-(2,3,4,5-tetramethyl-6H-cyclopenta[b]thiophen-6 Synthesis of -yl)silanamine

In a Schlenk flask, 2.3 g (12.9 mmol) of 2,3,4,5-tetramethyl-6H-cyclopenta[b]thiophene obtained above was quantitatively dissolved in 65 mL of THF and n-BuLi (1.05 eq, 5.4 mL) was added dropwise at -78 ^o C. After overnight reaction at RT, a silane compound (6-(tert-butoxy)hexyl)methyl silane (tether silane, 1.05 eq, 3.7 mL) was quantitatively dissolved in another Schlenk flask, 30 mL of THF was added, and the temperature was lowered to 0 ^o C. After transferring to the reaction solution, it was incubated at RT overnight. The solvent was dried by distillation under reduced pressure, filtered with hexane, and concentrated. 30 mL of t-BuNH ₂ was added and reacted at RT overnight. After distillation under reduced pressure, drying the solvent, filtering with hexane, and concentrating, a brown oil product (5 g) was obtained with a yield of 86.2%.

¹ H-NMR (in CDCl ₃ , 500 MHz): 3.32 (m, 4H), 2.35 (s, 6H), 2.25 (s, 6H), 2.11 (s, 6H), 2.07 (s, 3H), 2.05 ( s, 3H), 1.51-1.27 (m, 20H), 1.19 (s, 36H), 0.15 (s, 3H), 0.0 (s, 3H)

(5) Synthesis of Silane bridged dimethyl titanium compound

2.97 g (6.6 mmol) of 1-(6-(tert-butoxy)hexyl)-N-(tert-butyl)-1-methyl-1-(2,3,4,5-tetramethyl-6H-cyclopenta[b]thiophen-6-yl)silanamine obtained above was quantitatively transferred to a Schlenk flask and dissolved in 33 mL of MTBE. n-BuLi (2.05 eq, 5.4 mL) was added dropwise at -78 ^o C and reacted at RT overnight. MMB (2.5 eq, 5.5 mL) and TiCl ₄ (1 eq, 6.6 mL) were added dropwise at -78 ^o C and reacted at RT overnight. After drying in vacuo and filtering with hexane, DME (3 eq, 2.1 mL) was added dropwise. After overnight reaction at RT, the solvent was vacuum dried, filtered with hexane, and concentrated to obtain 2.8 g of a transition metal compound (silane bridged dimethyl titanium compound) with a yield of 81.3%.

¹ H-NMR (in CDCl ₃ , 500 MHz): 3.32 (m, 4H), 2.47 (s, 3H), 2.34 (s, 6H), 2.30 (s, 6H), 1.95 (s, 3H), 1.50 ( s, 18H), 1.40 (s, 6H),1.31-1.26 (m, 20H),1.18 (s, 18H), 0.49 (s, 3H), 0.48 (s, 3H), 0.46 (s, 3H), 0.34 (s, 3H), -0.09 ( s, 3H) -0.23(s, 3H)

Comparative synthesis example 3

In a dried 250 mL schlenk flask, 1.622 g (10 mmol) of fluorene was added, and 200 mL of THF was injected under argon. Then, the obtained solution was cooled to 0 ^o C, and n-BuLi (2.5 M in hexane, 4.8 mL, 12 mmol) was slowly added dropwise. Then, the temperature of the reaction mixture was slowly raised to room temperature, and the reaction mixture was stirred at room temperature overnight.

Meanwhile, in a separate 250 mL schlenk flask, dichlorodimethylsilane (1.2 mL, 10 mmol, Fw 129.06, d 1.07 g/mL) was dissolved in 30 mL of hexane, and the solution was cooled to -78 ^o C. Then, the previously prepared lithiated solution was slowly added to the solution. The resulting solution was stirred at room temperature for one day.

Meanwhile, 10 mmol of TMCP was dissolved in THF, and the solution was cooled to 0 ^o C. Subsequently, n-BuLi (2.5 M in hexane, 4.8 mL, 12 mmol) was slowly added dropwise to the solution, and the resulting solution was stirred at room temperature for one day. Thereafter, the chloro(9H-fluoren-9-yl)dimethylsilane solution and the lithiated-TMCP solution, which had been stirred for one day, were mixed using a cannula. At this time, whichever solution was transferred using the cannula did not affect the experimental results. The mixture of the two solutions was stirred for one day, and then 50 mL of water was added to the flask to terminate the reaction and separate the organic layer. After adding MgSO ₄ to the organic layer to remove moisture and drying under reduced pressure, (9H-fluoren-9-yl)(2,3,4,5-tetramethylcyclopenta-2,4-dien-1-yl)silane was obtained as a yellow powder (3.53 g, 10.25 mmol, 100% yield, 100% purity based on NMR, Mw 344.56 g/mol).

^1H NMR (500 MHz, CDCl ₃ ): -0.36 (6H, s), 1.80 (6H, s), 1.94 (6H, s), 3.20 (1H, s), 4.09 (1H, s), 7.28~7.33 (4H, m), 7.52 (2H, d), 7.83 (2H, d).

In a 250 mL schlenk flask dried in an oven, the previously prepared intermediate was placed, dissolved in diethyl ether, 2.1 equivalents of n-BuLi (8.6 mL, 21.5 mmol) were added dropwise, and stirred overnight. The resulting product was dried under vacuum, and the resulting slurry was filtered through a schlenk filter to obtain a yellow solid. The yellow solid was placed in a new 250 mL schlenk flask, and 50 mL of toluene was added to prepare a suspension.

Meanwhile, 1 equivalent of ZrCl ₄ (THF) ₂ was added to a 250 mL schlenk flask prepared separately in a glove box, and toluene was added to disperse it. Then, the Zr solution and the previously prepared lithiated ligand solution were cooled to -78 ^o C. Then, the previously prepared lithiated ligand solution was slowly injected into the mixture. Then, the temperature of the obtained mixture was slowly raised to room temperature, and the mixture was stirred for one day.

The reaction product thus obtained was filtered using a Schlenk filter under argon to remove LiCl, but the solubility of the product was poor, so dimethylsilylene(tetramethylcyclopentadienyl)(9H-fluoren-9-yl)zirconium dichloride was obtained in the form of a filtercake (3.551 g, 6.024 mmol, 61.35% yield, 85.6 wt% purity based on NMR (the remaining content is LiCl), Mw 504.68 g/mol).

¹ H NMR (500 MHz, CDCl ₃ ): 1.30 (6H, s), 1.86 (6H, s), 1.95 (6H, s), 7.21 (2H, m), 7.53 (2H, m), 7.65 (2H, m), 8.06 (2H, m).

Comparative synthesis example 4

From the reaction between tBu-O-(CH ₂ ) ₆ Cl compound and Mg(0) in the solvent of diethyl ether (Et ₂ O), 0.14 mol of tBu-O-(CH ₂ ) ₆ MgCl solution, a Grignard reagent, was obtained. To this, MeSiCl ₃ compound (24.7 mL, 0.21 mol) was added at -100 ^o C, and after stirring at room temperature for more than 3 hours, the filtered solution was dried in vacuo to obtain the compound of tBu-O-(CH ₂ ) ₆ SiMeCl ₂ (yield 84%). - A solution of tBu-O-(CH ₂ ) ₆ SiMeCl ₂ (7.7 g, 0.028 mol) in hexane (50 mL) at -78 ^o C was slowly added a solution of fluorenyllithium (4.82 g, 0.028 mol) in hexane (150 mL) over 2 h. The white precipitate (LiCl) was filtered off, and the desired product was extracted with hexane, and all volatiles were dried in vacuo to give (tBu-O-(CH ₂ ) ₆ )SiMe(9-C ₁₃ H ₁₀ ) as a pale yellow oil (yield 99%).

THF solvent (50 mL) was added here, and the mixture was reacted with C ₅ H ₅ Li (2.0 g, 0.028 mol)/THF (50 mL) solution at room temperature for more than 3 hours. All volatile substances were vacuum-dried and extracted with hexane to obtain the final ligand, (tBu-O-(CH ₂ ) ₆ )(CH ₃ )Si(C ₅ H ₅ )(9-C ₁₃ H ₁₀ ) compound in the form of an orange oil (yield 95%). The structure of the ligand was confirmed by 1H NMR.

Also, 2 equivalents of ⁿ -BuLi were added to a solution of (tBu-O-(CH ₂ ) ₆ )(CH ₃ )Si(C ₅ H ₅ )(9-C ₁₃ H ₁₀ )(12 g, 0.028 mol)/THF (100 mL) at -78 o C, and the mixture was allowed to react for more than 4 hours while warming to room temperature to obtain the compound of (tBu-O-(CH ₂ ) ₆ )(CH ₃ )Si(C ₅ H ₅ Li)(9-C ₁₃ H ₁₀ Li) in the form of an orange solid (yield 81%). Also, dilithium salt (2.0 g, 4.5 mmol)/ether (30 mL) solution was slowly added to a suspension solution of ZrCl ₄ (1.05 g, 4.50 mmol)/ether (30 mL) at -78 ^o C and further reacted at room temperature for 3 h. All volatile substances were vacuum-dried, and the obtained oily liquid substance was filtered by adding dichloromethane solvent. After the filtered solution was vacuum-dried, hexane was added to induce a precipitate. The obtained precipitate was washed with hexane several times to obtain racemic-(t Bu-O-(CH ₂ ) 6 )(CH ₃ )Si(C ₅ H ₄ )(9-C ₁₃ H ₉ )ZrCl ₂ compound in the form of a _red solid (yield 54%).

<Manufacture of supported catalyst>

Manufacturing Example 1: Manufacturing of a Hybrid Supported Metallocene Catalyst

First, silica (SP952 manufactured by Grace Davison) was prepared as a carrier by dehydration and drying under vacuum at a temperature of 200 ^o C for 12 hours.

Then, 3.0 kg of toluene solution was placed in a 20 L capacity stainless steel (SUS) high-pressure reactor, 800 g of silica (Grace Davison, SP952) prepared previously was added, and the reactor temperature was raised to 40 ^o C while stirring. After the silica was sufficiently dispersed for 60 minutes, 6 kg of 10 wt% methylaluminoxane (MAO)/toluene solution was added and slowly reacted while stirring at 200 rpm at 70 ^o C for 1 hour. After completion of the reaction, the reaction solution was decantated and washed several times with a sufficient amount of toluene until the unreacted aluminum compound was completely removed.

After the reactor temperature was raised to 50 ^o C, 0.2 mmol of the first metallocene compound prepared in Synthesis Example 1 was dissolved in toluene and added, and the reaction was carried out for 2 hours while stirring at 200 rpm at 40 ^o C.

After completion of the reaction, 0.1 mmol of the second metallocene compound prepared in Synthesis Example 2 was dissolved in toluene, and the mixture was stirred at 200 rpm at 40 ^o C for 2 hours.

After the above reaction was completed, stirring was stopped, and the reaction solution was allowed to settle for 30 minutes, and then decantated. After that, it was washed with a sufficient amount of toluene, and then 50 mL of toluene was added again, stirring was continued for 10 minutes, and then stopped and washed with a sufficient amount of toluene to remove compounds that did not participate in the reaction. After that, 3.0 kg of hexane was added to the reactor, stirred, and then the hexane slurry was transferred to a filter and filtered.

A hybrid supported catalyst was obtained by primary drying under reduced pressure at room temperature for 5 hours and secondary drying under reduced pressure at 50 ^o C for 4 hours.

Comparative Manufacturing Example 1: Manufacturing of Hybrid Supported Metallocene Catalyst

100 mL of toluene was placed in a 300 mL glass reactor, 10 g of silica (SP2410 manufactured by Grace Davison) was added, and the reactor temperature was raised to 40 ^o C while stirring. 30 mL of a 30 wt% methylaluminoxane (MAO)/toluene solution (Albemarle) was added, the temperature was raised to 70 ^o C, and the reactor was stirred at 200 rpm for 12 hours.

Meanwhile, 0.30 g (0.15 mmol) of the metallocene compound prepared in Comparative Synthesis Example 1, 0.26 g (0.225 mmol) of the metallocene compound prepared in Comparative Synthesis Example 3, 30 mL of toluene, and 0.5 g of triisobutyl aluminum were placed in a schlenk flask, and stirred at room temperature for 15 minutes. Then, the obtained mixture was placed in the organic reactor, the temperature of the glass reactor was raised to 70 ^o C, and stirred for 2 hours.

Afterwards, the temperature of the reactor was lowered to room temperature, stirring was stopped, and the reaction product was allowed to stand for 10 minutes and then decanted. Then, 100 mL of hexane was added to the reactor to obtain a slurry, which was then transferred to a Schlenk flask and decanted. The resulting reaction product was dried under reduced pressure at room temperature for 3 hours to obtain a supported catalyst.

Comparative Manufacturing Example 2: Manufacturing of Hybrid Supported Metallocene Catalyst

A hybrid supported catalyst was manufactured using the same method as Manufacturing Example 1, except that instead of the metallocene compounds of Synthesis Examples 1 and 2, the first metallocene compound of Comparative Synthesis Example 2 and the second metallocene compound of Comparative Synthesis Example 4 were used, so that the ratio of the first metallocene compound of Comparative Synthesis Example 2 and the second metallocene compound of Comparative Synthesis Example 4 was 50:50 by weight.

<Production of polyethylene copolymer>

Example 1

Ethylene-1-hexene was slurry polymerized in the presence of the hybrid supported catalyst prepared in Manufacturing Example 1.

At this time, the polymerization reactor was a continuous polymerizer of isobutane (i-C4) slurry loop process, with a reactor volume of 140 L and a reaction flow rate of approximately 7 m/s. The gases (ethylene, hydrogen) required for polymerization and 1-hexene, a comonomer, were continuously fed constantly, and the individual flow rates were adjusted to suit the target product. At this time, the hydrogen input amount was adjusted to 1.5 ppm relative to ethylene. In addition, the concentrations of all gases and 1-hexene, a comonomer, in Example 1 were confirmed by an on-line gas chromatograph. The supported catalyst was prepared as an isobutane slurry having a concentration as shown in Table 1 below and fed, the reactor pressure was maintained at approximately 40 bar, and the polymerization temperature was performed at approximately 85 ^o C.

Comparative Example 1

Ethylene-1-hexene was slurry polymerized using the same method as in Example 1, except that the supported catalyst manufactured in Comparative Manufacturing Example 1 was used instead of the supported catalyst manufactured in Manufacturing Example 1.

Comparative Example 2

Ethylene-1-hexene was slurry polymerized using the supported catalyst manufactured in Comparative Manufacturing Example 1, which was manufactured in the same manner as Comparative Example 1, but with the hydrogen input amount changed to 1.7 ppm.

Comparative Example 3

Ethylene-1-hexene was slurry polymerized using the same method as in Example 1, except that the supported catalyst manufactured in Comparative Manufacturing Example 2 was used instead of the supported catalyst manufactured in Manufacturing Example 1.

The precursor types and specific polymerization reaction conditions of the hybrid supported catalysts used in the slurry polymerization of ethylene-1-hexene according to Example 1 and Comparative Examples 1 to 3 are as shown in Table 1 below.

Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Metallocene catalyst first precursor Synthetic example
1 Comparative synthesis example
1 Comparative synthesis example
1 Comparative synthesis example
2 Metallocene catalyst second precursor Synthetic example
2 Comparative synthesis example
3 Comparative synthesis example
3 Comparative synthesis example
4 Polymerization temperature ( ^o C) 80 80 80 80 Ethylene input (kg/hr) 25 25 25 25 Hydrogen input ^a (ppm) 1.5 1.5 1.7 5.0 1-Hexene input ^b (wt%) 2.6 2.7 2.0 8.0 Catalytic activity
(kg PE/gㆍcatㆍhr) 5.5 4.0 4.2 6.0

In the above Table 1, a and b are the hydrogen input amount expressed in ppm and the 1-hexene input amount expressed in wt% based on the total weight of ethylene supplied to the continuous polymerization reactor. In addition, the catalytic activity (Activity, kg PE/gㆍcatㆍhr) is a value calculated as the ratio of the weight of polyethylene copolymer (kg PE) produced per the content of supported catalyst (gㆍCat) used per unit time (h).

<Evaluation of properties of polyethylene copolymer and blown film>

Test Example 1: Evaluation of physical properties of polyethylene copolymer

The physical properties of the polyethylene copolymers manufactured in Example 1 and Comparative Examples 1 to 3 were measured by the methods described below and are shown in Table 2.

(1) Melt index (MI) _2.16 )

The melt index (MI _2.16 ) was measured at 190 ^° C under a load of 2.16 kg according to the American Society for Testing and Materials standard ASTM D 1238 (Condition E, 190 ^° C, 2.16 kg), and was expressed as the weight (g) of the polymer melted for 10 minutes.

(2) Density (g/cm) ³ )

The density of polyethylene copolymer was measured according to the American Society for Testing and Materials standard ASTM D 1505.

(3) Weight average molecular weight (Mw, g/mol) and molecular weight distribution (Mw/Mn, PDI)

For the ethylene-1-hexene copolymers of the examples and comparative examples, the weight average molecular weight (Mw) and number average molecular weight (Mn) were measured using gel permeation chromatography (GPC, manufactured by Water), and the 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 Waters PL-GPC220 gel permeation chromatography (GPC) device was used, and a Polymer Laboratories PLgel MIX-B 300 mm column was used. The measurement temperature was 160 °C, 1,2,4-trichlorobenzene was used as a solvent, and the flow rate was 1 mL/min. The samples of ethylene-1-hexene copolymer were each pretreated by dissolving in 1,2,4-trichlorobenzene containing 0.0125% BHT at 160 ^° C for 10 hours using a GPC analysis device (PL-GP220), preparing a concentration of 10 mg/10 mL, and then supplying 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 weights of the polystyrene standard specimens were 2000 g/mol, 10000 g/mol, 30000 g/mol, 70000 g/mol, 200000 g/mol, 700000 g/mol, 2000000 g/mol, 4000000 g/mol, and 10000000 g/mol, nine types.

(4) Comb polymer content and weight average molecular weight of the main chain within the comb polymer (comb main chain Mw)

The rheological properties and molecular weight distribution of the ethylene-1-hexene copolymer samples of the examples and comparative examples were measured using a rotational rheometer and GPC. Then, the comb polymer content (Comb, wt%) in the polyethylene copolymer and the weight average molecular weight of the main chain in the comb polymer (comb main chain Mw) were selected as the structural parameters of the sample, and arbitrary values of the selected structural parameters were set. Thereafter, the rheological properties and molecular weight distribution were predicted from the arbitrary values. An arbitrary value whose error value between the predicted value and the measured value is less than 5% was derived as a confirmed value, and again, the process of comparing the predicted rheological values with the measured values from the process of setting the arbitrary values to derive a confirmed value was repeated, and 70 confirmed values were derived. The average value of the derived confirmed values is described.

Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 MI _2.16 [g/10min] 0.28 0.3 0.5 1.0 Density [g/cm ³ ] 0.930 0.927 0.935 0.920 Mw [X10 ³ g/mol] 95,000 92,000 101,000 120,000 PDI (Mw/Mn) 3.4 3.4 3.4 2.4 Comb [wt%] 30 20 21 doesn't exist Comb main chain Mw
[X10 ³ g/mol] 189.4 187.1 193.9 doesn't exist

Test Example 2: Evaluation of physical properties of blown film

A blown film was manufactured using the polyethylene copolymers manufactured in Example 1 and Comparative Examples 1 to 3 as follows, and the shrinkage ratio according to BUR was measured, which is shown in Table 3.

(5) Shrinkage rate according to BUR

Using the ethylene-1-hexene copolymer of the examples and comparative examples, films having a thickness of 60 ㎛ were manufactured at various blow up ratios (BUR) under the following conditions using a film forming machine, and then the shrinkage was measured in the machine direction (MD) and the transverse direction (TD) at shrinkage temperatures of 130 ^o C, 140 ^o C, and 150 ^o C according to the method of the American Society for Testing and Materials ASTM D 2732. Among these, the TD shrinkage ratio according to BUR is shown in Table 3 below.

Film release conditions

Blowup Ratio (BUR): 2.3, 2.5, 3.0

Screw rpm: 40 rpm

Processing temperature: 180 ^o C

Die gap: 2.0 mm

Dies: 100 mm

Shrinkage temperature ( ^o C) TD shrinkage rate (%) according to BUR 2.3 2.5 3.0 Example 1 130 11.5 16.5 23.3 140 13.3 16.6 26.5 150 16.8 20.2 27.0 Comparative Example 1 130 7.0 10.2 11.4 140 8.0 10.5 13.5 150 12.0 13.0 15.0 Comparative Example 2 130 6.3 10.2 10.5 140 8.1 10.2 12.5 150 11.1 13.5 14.2 Comparative Example 3 130 2.5 3.0 3.0 140 2.0 2.7 1.7 150 1.0 1.0 2.0

As shown in Tables 2 and 3 above, the examples according to the present invention optimized the content of comb polymer (Comb) structure as a branched polymer along with density and melt index, thereby increasing shrinkage behavior according to BUR and improving shrinkage ratio in the TD direction, thereby confirming that heat shrinkage packaging performance is significantly improved.

On the other hand, it was confirmed that Comparative Examples 1 and 2, in which the comb-shaped polymer content was not optimized, had a problem in which the shrinkage in the TD direction was reduced compared to Example 1. In addition, it was confirmed that Comparative Example 3, in which there was no LCB, had a problem in which the shrinkage in the TD direction was small even though the BUR increased and the shrinkage temperature increased.

Claims (10)

The density is 0.928 g/cm ³ to 0.935 g/cm ³ ,
The melting index (MI _2.16 , 190 ^o C, 2.16 kg load) is 0.25 g/10 min to 0.45 g/10 min,
The content of the branched polymer structure is 26 to 34 wt% based on the total weight of the polyethylene copolymer.
Polyethylene copolymer.
In the first paragraph,
The above polyethylene copolymer has a weight average molecular weight of the main chain within the branched polymer structure of 180,000 g/mol to 195,000 g/mol.
Polyethylene copolymer.
In the first paragraph,
The above polyethylene copolymer has a weight average molecular weight of 92,000 g/mol to 110,000 g/mol.
Polyethylene copolymer.
In the first paragraph,
The above polyethylene copolymer has a molecular weight distribution (Mw/Mn) of 3.3 to 3.5.
Polyethylene copolymer.
In the first paragraph,
The above polyethylene copolymer comprises ethylene and alpha-olefin.
Polyethylene copolymer.
In paragraph 5,
The above alpha-olefin is at least one selected from the group consisting of propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, and mixtures thereof.
Polyethylene copolymer.
In the first paragraph,
The above polyethylene copolymer is an ethylene 1-hexene copolymer.
Polyethylene copolymer.
In the first paragraph,
The above polyethylene copolymer is produced in the presence of a metallocene catalyst.
Polyethylene copolymer.
A blown film comprising the polyethylene of claim 1.
In Article 9,
The above film has a shrinkage in the transverse direction (TD) of 10% to 15% when measured under conditions of 130 ^o C for a film formed with a film thickness of 60 ㎛ at a blow up ratio (BUR) of 2.3,
A film formed with a film thickness of 60 ㎛ at a blow up ratio (BUR) of 3.0 has a shrinkage in the transverse direction (TD) of 20% or more measured under conditions of 130 ^o C.
Blown film.