TECHNICAL FIELD

The present invention relates to an olefinic polymer and a preparation method therefor. More specifically, the present invention relates to an olefinic polymer having excellent heat resistance and a preparation method therefore.

BACKGROUND ART

A metallocene catalyst, which is one of the catalysts used in the polymerization of olefins, is a compound in which a ligand such as cyclopentadienyl, indenyl, and cycloheptadienyl is coordinated to a transition metal or a transition metal halide compound, and has a sandwich structure in its basic form.

In a Ziegler-Natta catalyst, which is another catalyst used in the polymerization of olefins, the metal component serving as the active sites is dispersed on an inert solid surface, whereby the properties of the active sites are not uniform. On the other hand, since a metallocene catalyst is a single compound having a specific structure, it is known as a single-site catalyst in which all active sites have the same polymerization characteristics. A polymer polymerized by such a metallocene catalyst is characterized by a narrow molecular weight distribution, a uniform distribution of comonomers, and a higher copolymerization activity than Ziegler-Natta catalysts.

Meanwhile, a linear low-density polyethylene (LLDPE) is produced by copolymerizing ethylene and an alpha-olefin at a low pressure using a polymerization catalyst. It has a narrow molecular weight distribution and short chain branches (SCBs) having a certain length, but generally does not have long chain branches (LCBs). Films manufactured from a linear low-density polyethylene have high strength at breakage, elongation, tear strength, and impact strength in addition to the characteristics of common polyethylene. They are widely used for stretch films and overlap films to which conventional low-density polyethylene or high-density polyethylene is hardly applicable.

However, in order to utilize the olefinic polymer prepared by the metallocene catalyst for spout pouches for high-temperature liquid containers, excellent heat resistance is required.

DISCLOSURE
Technical Problem

An object of the present invention is to provide an olefinic polymer having excellent heat resistance.

Another object of the present invention is to provide a method for preparing the olefinic polymer.

Technical Solution

In one general aspect, there is provided an olefinic polymer that has a density of 0.9 to 0.95 g/cm³, preferably 0.91 to 0.945 g/cm³, and satisfies the following Equations 1a and 2a:

224.02×d−86.257<Tm [Equation 1a]

219.64×d−95.767<Tc [Equation 2a]

- wherein Tm is a melting temperature (° C.), Tc is a crystallization temperature (° C.), and d is a density (g/cm³) of the olefinic polymer.

In an embodiment of the present invention, the olefinic polymer satisfies the following Equations 1b and 2b:

Tm<224.02×d−82.257 [Equation 1b]

Tc<219.64×d−91.767 [Equation 2b]

In an embodiment of the present invention, the olefinic polymer may have (1) a density of 0.918 to 0.945 g/cm³; (2) a melt index (I_2.16) of 0.1 to 5.0 g/10 min under a load of 2.16 kg, when measured at 190° C.; (3) a melt flow ratio (MFR) of 17 or more, when measured at 190° C., as a ratio of the melt index (I_21.6) under a load of 21.6 kg to the melt index (I_2.16) under a load of 2.16 kg; (4) a melting temperature of 120° C. or more; and (5) a crystallization temperature of 107° C. or more.

In an embodiment of the present invention, the olefinic polymer may be prepared by polymerizing an olefinic monomer in the presence of a hybrid catalyst comprising at least one first transition metal compound represented by the following Formula 1; and at least one second transition metal compound selected from a compound represented by the following Formula 2 and a compound represented by the following Formula 3:

[Image Omitted]

- wherein M₁and M₂are different from each other and are each independently titanium (Ti), zirconium (Zr), or hafnium (Hf),
- X is each independently halogen, C_1-20alkyl, C_2-20alkenyl, C_2-20alkynyl, C_6-20aryl, C_1-20alkyl C_6-20aryl, C_6-20aryl C_1-20alkyl, or C_1-20alkylamido, and
- R₁to R₁₀are each independently hydrogen, substituted or unsubstituted C_1-20alkyl, substituted or unsubstituted C_2-20alkenyl, substituted or unsubstituted C_6-20aryl, substituted or unsubstituted C_1-20alkyl C_6-20aryl, substituted or unsubstituted C_6-20aryl C_1-20alkyl, substituted or unsubstituted C_1-20heteroalkyl, substituted or unsubstituted C_3-20heteroaryl, substituted or unsubstituted C_1-20alkylamido, substituted or unsubstituted C_6-20arylamido, substituted or unsubstituted C_1-20alkylidene, or substituted or unsubstituted C_1-20silyl, provided that R₁to R₁₀are each independently capable of being linked to adjacent groups to form a substituted or unsubstituted saturated or unsaturated C_4-20ring.

In an embodiment of the present invention, M₁and M₂are different from each other and may each be zirconium or hafnium, each X may be halogen or C_1-20alkyl, and R₁to R₁₀may each be hydrogen, substituted or unsubstituted C_1-20alkyl, substituted or unsubstituted C_1-20alkenyl, or substituted or unsubstituted C_6-20aryl.

In a preferred embodiment of the present invention, M₁may be hafnium, M₂may be zirconium, and X may be chlorine or methyl.

In a preferred embodiment of the present invention, the first transition metal compound may be at least one of the transition metal compounds represented by the following Formulas 1-1 and 1-2, and the second transition metal compound may be at least one of transition metal compounds represented by the following Formulas 2-1, 2-2, and 3-1:

[Image Omitted]

- wherein Me is a methyl group.

In an embodiment of the present invention, a molar ratio of the first transition metal compound to the second transition metal compound is in a range of 100:1 to 1:100.

In an embodiment of the present invention, the catalyst may comprise at least one cocatalyst selected from the group consisting of a compound represented by the following Formula 4, a compound represented by the following Formula 5, and a compound represented by the following Formula 6:

[Image Omitted]

- in Formula 4, n is an integer of 2 or more, and R_ais a halogen atom, a C_1-20hydrocarbon group, or C_1-20hydrocarbon group substituted with halogen,
- in Formula 5, D is aluminum (Al) or boron (B), and R_b, R_c, and R_dare each independently a halogen atom, a C_1-20hydrocarbon group, a C_1-20hydrocarbon group substituted with halogen, or a C_1-20alkoxy group, and
- in Formula 6, L is a neutral or cationic Lewis base, [L-H]⁺ and [L]⁺ are a Bronsted acid, Z is a Group 13 element, and A is each independently a substituted or unsubstituted C_6-20aryl group, or a substituted or unsubstituted C_1-20alkyl group.

In an embodiment of the present invention, the catalyst may further comprise a carrier supporting the transition metal compound, the cocatalyst compound, or both.

In a preferred embodiment of the present invention, the carrier may comprise at least one selected from the group consisting of silica, alumina, and magnesia.

Here, the total amount of a hybrid transition metal compound supported on the carrier is 0.001 to 1 mmole based on 1 g of the carrier, and the total amount of the cocatalyst compound supported on the carrier is 2 to 15 mmole based on 1 g of the carrier.

In an embodiment of the present invention, the olefinic polymer is a copolymer of an olefinic monomer and an olefinic comonomer. Specifically, the olefinic monomer may be ethylene, and the olefinic comonomer may be 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, and 1-hexadecene. Preferably, the olefinic polymer is a linear low density polyethylene wherein the olefinic monomer is ethylene and the olefinic comonomer is 1-hexene.

In another general aspect, there is provided a method for preparing an olefinic polymer, which includes: obtaining an olefinic polymer by polymerizing the olefinic monomer in the presence of a hybrid catalyst comprising at least one first transition metal compound represented by the following Formula 1 above; and at least one second transition metal compound selected from a compound represented by the following Formula 2 above and a compound represented by the following Formula 3 above, wherein the olefinic polymer has a density of 0.9 to 0.95 g/cm³, preferably 0.91 to 0.945 g/cm³, and satisfies the following Equations 1a and 2a:

224.02×d−86.257<Tm [Equation 1a]

219.64×d−95.767<Tc [Equation 2a]

- wherein Tm is a melting temperature (° C.), Tc is a crystallization temperature (° C.), and d is a density (g/cm³) of the olefinic polymer.

In an embodiment of the present invention, the olefinic polymer satisfies the following Equations 1b and 2b:

Tm<224.02×d−82.257 [Equation 1b]

Tc<219.64×d−91.767 [Equation 2b]

In an embodiment of the present invention, the polymerization of an olefinic monomer may be performed by gas-phase polymerization, and specifically, the polymerization of an olefinic monomer may be performed in a gas-phase fluidized bed reactor.

Advantageous Effects

The olefinic polymer according to an embodiment of the present invention has excellent heat resistance and may be utilized in spout pouches for high-temperature liquid containers, or the like. In particular, the olefinic polymer according to an embodiment of the present invention has a specific relationship between a melting temperature and a crystallization temperature respect to density and has a relatively high melting and crystallization temperatures at the same level of density. Thus, it is possible to provide an olefinic polymer that may be applied to various fields such as adhesives, films, and packaging materials by changing the density according to its use during polymerization of the olefinic polymer.

DESCRIPTION OF DRAWINGS

FIG. 1 is a graph illustrating a result of differential scanning calorimetry (DSC) measurement of olefinic polymers of Example 1 and Comparative Example 1.

FIG. 2 is a graph illustrating a result of differential scanning calorimetry measurement of olefinic polymers of Example 2 and Comparative Example 2.

BEST MODE

Hereinafter, the present invention will be described in detail.

Olefinic Polymer

According to an embodiment of the present invention, an olefinic polymer that has a density of 0.9 to 0.95 g/cm³and satisfies the following Equations 1a and 2a is provided:

224.02×d−86.257<Tm [Equation 1a]

219.64×d−95.767<Tc [Equation 2a]

- wherein Tm is a melting temperature (° C.), Tc is a crystallization temperature (° C.), and d is a density (g/cm³) of the olefinic polymer.

In an embodiment of the present invention, the olefinic polymer satisfies the following Equations 1b and 2b:

Tm<224.02×d−82.257 [Equation 1]

Tc<219.64×d−91.767 [Equation 2]

In an embodiment of the present invention, the olefinic polymer may have (1) a density of 0.918 to 0.945 g/cm³; (2) a melt index (I_2.16) of 0.1 to 5.0 g/10 min under a load of 2.16 kg, when measured at 190° C.; (3) a melt flow ratio (MFR) of 17 or more, when measured at 190° C., as a ratio of the melt index (I_21.6) under a load of 21.6 kg to the melt index (I_2.16) under a load of 2.16 kg; (4) a melting temperature of 120° C. or more; and (5) a crystallization temperature of 107° C. or more.

In an embodiment of the present invention, the olefinic polymer has a density of 0.9 to 0.95 g/cm³. Preferably, the olefinic polymer may have a density of 0.91 to 0.945 g/cm³, 0.91 to 0.93 g/cm³, 0.918 to 0.945 g/cm³, 0.918 to 0.942 g/cm³, or 0.915 to 0.925 g/cm³.

In an embodiment of the present invention, the olefinic polymer has a melt index (I_2.16) of 0.1 to 5.0 g/10 min under a load of 2.16 kg, when measured at 190° C. Preferably, the olefinic polymer may have a melt index of 0.3 to 4.0 g/10 min, 0.5 to 3.5 g/10 min, or 0.5 to 3.0 g/10 min under a load of 2.16 kg, when measured at 190° C.

In an embodiment of the present invention, the olefinic polymer has a melt flow ratio (MFR) of 17 or more when measured at 190° C., as a ratio of a melt index (I_21.6) under a load of 21.6 kg to a melt index (I_2.16) under a load of 2.16 kg. Preferably, the olefinic polymer may have an MFR of 20 or more, 22 or more, or 20 to 50.

In an embodiment of the present invention, the olefinic polymer has a melting temperature (Tm) of 118° C. or more. Preferably, the olefinic polymer may have a melting temperature of 120° C. or more, or 120 to 130° C.

In an embodiment of the present invention, the olefinic polymer has a crystallization temperature (Tc) of 106° C. or more. Preferably, the olefinic polymer may have the crystallization temperature of 107° C. or more, or 107 to 117° C.

The olefinic polymer according to an embodiment of the present invention is prepared by polymerizing an olefinic monomer in the presence of a hybrid catalyst comprising at least one first transition metal compound represented by the following Formula 1; and at least one second transition metal compound selected from a compound represented by the following Formula 2 and a compound represented by the following Formula 3:

[Image Omitted]

- wherein M₁and M₂are different from each other and are each independently titanium (Ti), zirconium (Zr), or hafnium (Hf). Specifically, M₁and M₂are different from each other and may each be zirconium or hafnium. Preferably, M₁may be hafnium and M₂may be zirconium.

X is each independently halogen, C_1-20alkyl, C_2-20alkenyl, C_2-20alkynyl, C_6-20aryl, C_1-20alkyl C_6-20aryl, C_6-20aryl C_1-20alkyl, C_1-20alkylamido, or C_6-20arylamido. Specifically, each X may be halogen or C_1-20alkyl.

Preferably, X may be chlorine or methyl.

R₁to R₁₀are each independently hydrogen, substituted or unsubstituted C_1-20alkyl, substituted or unsubstituted C_2-20alkenyl, substituted or unsubstituted C_6-20aryl, substituted or unsubstituted C_1-20alkyl C_6-20aryl, substituted or unsubstituted C_6-20aryl C_1-20alkyl, substituted or unsubstituted C_1-20heteroalkyl, substituted or unsubstituted C_3-20heteroaryl, substituted or unsubstituted C_1-20alkylamido, substituted or unsubstituted C_6-20arylamido, substituted or unsubstituted C_1-20alkylidene, or substituted or unsubstituted C_1-20silyl, provided that R₁to R₁₀are each independently capable of being linked to adjacent groups to form a substituted or unsubstituted saturated or unsaturated C_4-20ring. Specifically, R₁to R₁₀may each be hydrogen, substituted or unsubstituted C_1-20alkyl, substituted or unsubstituted C_1-20alkenyl, or substituted or unsubstituted C_6-20aryl.

In an embodiment of the present invention, M₁and M₂are different from each other and may each be zirconium or hafnium, X may each be halogen or C_1-20alkyl, and R₁to R₁₀may each be hydrogen, substituted or unsubstituted C_1-20alkyl, substituted or unsubstituted C_1-20alkenyl, or substituted or unsubstituted C_6-20aryl.

In a preferred embodiment of the invention, M₁may be hafnium, M₂may be zirconium, and X may be chlorine or methyl.

In a preferred embodiment of the present invention, the first transition metal compound may be at least one of the transition metal compounds represented by the following Formulas 1-1 and 1-2, and the second transition metal compound may be at least one of transition metal compounds represented by the following Formulas 2-1, 2-2, and 3-1:

[Image Omitted]

- wherein Me is a methyl group.

In an embodiment of the present invention, a molar ratio of the first transition metal compound to the second transition metal compound is in a range of 100:1 to 1:100. Preferably, a molar ratio of the first transition metal compound to the second transition metal compound is in a range of 50:1 to 1:50. Preferably, a molar ratio of the first transition metal compound to the second transition metal compound is in a range of 10:1 to 1:10.

In an embodiment of the present invention, the catalyst may comprise at least one cocatalyst compound selected from the group consisting of a compound represented by the following Formula 4, a compound represented by the following Formula 5, and a compound represented by the following Formula 6:

[Image Omitted]

- wherein n may be an integer of 2 or more, and R_amay be a halogen atom, C_1-20hydrocarbon, or C_1-20hydrocarbon substituted with a halogen. Specifically, R_amay be methyl, ethyl, n-butyl, or isobutyl.

[Image Omitted]

- wherein D is aluminum (Al) or boron (B), and R_b, R_c, and R_dare each independently a halogen atom, a C_1-20hydrocarbon group, a C_1-20hydrocarbon group substituted with halogen, or a C_1-20alkoxy group. Specifically, when D is aluminum (Al), R_b, R_cand R_dmay each independently be methyl or isobutyl, and when D is boron (B), R_b, R_cand R_dmay each be pentafluorophenyl.

[L-H]^+[Z(A)₄]⁻ or [L]^+[Z(A)₄]⁻

- wherein L is a neutral or cationic Lewis base, [L-H]⁺ and [L]⁺are a Bronsted acid, Z is a Group 13 element, and A is each independently a substituted or unsubstituted C_6-20aryl group, or a substituted or unsubstituted C_1-20alkyl group. Specifically, [L-H]⁺ may be a dimethylanilinium cation, [Z(A)₄]⁻may be [B(C₆F₅)₄]⁻, and [L]⁺ may be [(C₆H₅)₃C]⁺.

Specifically, examples of the compound represented by Formula 4 above may include, but are not limited to, methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, butylaluminoxane, etc., preferably methylaluminoxane.

Examples of the compound represented by Formula 5 above may include, but are not limited to, trimethylaluminum, triethylaluminium, triisobutylaluminum, tripropylaluminum, tributylaluminum, dimethylchloroaluminum, triisopropylaluminum, tri-s-butyl aluminum, tricyclopentyl aluminum, tripentyl aluminum, triisopentyl aluminum, trihexyl aluminum, trioctyl aluminum, ethyl dimethyl aluminum, methyl diethyl aluminum, triphenyl aluminum, tri-p-tolylaluminum, dimethylaluminum methoxide, dimethylaluminum ethoxide, trimethylboron, triethylboron, triisobutylboron, tripropylboron, tributylboron, etc., preferably trimethylaluminum, triethylaluminum, and triisobutylaluminum.

Examples of the compound represented by Formula 6 above may include triethylammonium tetraphenylborate, tributylammonium tetraphenylborate, trimethylammonium tetraphenylborate, tripropylammonium tetraphenylborate, trimethylammonium tetra(p-tolyl)borate, trimethylammonium tetra(o,p-dimethylphenyl)borate, tributylammonium tetra(p-trifluoromethylphenyl)borate, trimethylammonium tetra(p-trifluoromethylphenyl)borate, tributylammonium tetrapentafluorophenylborate, N,N-diethylanilinium tetraphenylborate, N,N-diethylanilinium tetrapentafluorophenylborate, diethylammonium tetrapentafluorophenylborate, triphenylphosphonium tetraphenylborate, trimethylphosphonium tetraphenylborate, triethylammonium tetraphenylaluminate, tributylammonium tetraphenylaluminate, trimethylammonium tetraphenylaluminate, tripropylammonium tetraphenyl aluminate, trimethylammonium tetra(p-tolyl)aluminate, tripropylammonium tetra(p-tolyl)aluminate, triethylammonium tetra(o,p-dimethylphenyl)aluminate, tributylammonium tetra(p-trifluoromethylphenyl)aluminate, trimethylammonium tetra(p-trifluoromethylphenyl)aluminate, tributylammonium tetrapentafluorophenyl aluminate, N,N-diethylanilinium tetraphenylaluminate, N,N-diethylanilinium tetrapentafluorophenylaluminate, diethylammonium tetrapentatetraphenylaluminate, triphenylphosphonium tetraphenylaluminate, trimethylphosphonium tetraphenylaluminate, tripropylammonium tetra(p-tolyl)borate, triethylammonium tetra(o,p-dimethylphenyl)borate, tributylammonium tetra(p-trifluoromethylphenyl)borate, triphenylcarboniumtetra(p-trifluoromethylphenyl)borate, triphenylcarbonium tetrapentafluorophenylborate, etc.

In an embodiment of the present invention, the catalyst may further comprise a carrier supporting a transition metal compound, a cocatalyst compound, or both. Specifically, the carrier may support both of the transition metal compound and the cocatalyst compound.

Here, the carrier may comprise a material containing a hydroxyl group on its surface. Preferably, a material that has been dried to remove moisture form its surface and has a highly reactive hydroxyl group and siloxane group may be used. For example, the carrier may comprise at least one selected from the group consisting of silica, alumina, and magnesia. Specifically, silica, silica-alumina, and silica-magnesia dried at high temperatures may be used as carriers. They may usually comprise oxide, carbonate, sulfate, and nitrate components such as Na₂C, K₂CO₃, BaSO₄, and Mg(NO₃)₂. In addition, they may comprise carbon, zeolite, magnesium chloride, etc. However, the carrier is not limited thereto. It is not particularly limited as long as it can support the transition metal compound and the cocatalyst compound.

The carrier may have an average particle size of 10 to 250 μm, preferably 10 to 150 μm, and more preferably 20 to 100 μm.

The carrier may have a micropore volume of 0.1 to 10 cc/g, preferably 0.5 to 5 cc/g, and more preferably 1.0 to 3.0 cc/g.

The carrier may have a specific surface area of 1 to 1,000 m²/g, preferably 100 to 800 m²/g, and more preferably 200 to 600 m²/g.

In a preferred embodiment of the present invention, the carrier may be silica. Here, the drying temperature of the silica may be 200 to 900° C. The drying temperature may preferably be 300 to 800° C., and more preferably 400 to 700° C. If the drying temperature is lower than 200° C., there would be too much moisture so that the moisture on the surface and the cocatalyst may react. If the drying temperature exceeds 900° C., the structure of the carrier may collapse.

The dried silica may have a concentration of hydroxy groups of 0.1 to 5 mmol/g, preferably 0.7 to 4 mmol/g, and more preferably 1.0 to 2 mmol/g. If the concentration of hydroxy groups is less than 0.1 mmol/g, the amount supported of the first cocatalyst compound may be lowered. If the concentration of the hydroxy group exceeds 5 mmol/g, there may arise a problem that the catalyst component may be inactivated.

The total amount of the transition metal compound supported on a carrier may be 0.001 to 1 mmole based on 1 g of the carrier. When a ratio of the transition metal compound and the carrier satisfies the above range, an appropriate activity of the supported catalyst may be exhibited, which is advantageous from the viewpoint of maintaining the activity of the catalyst and economic efficiency.

The total amount of the cocatalyst compound supported on a carrier may be 2 to 15 mmole based on 1 g of the carrier. If a ratio of the cocatalyst compound and the carrier satisfies the above range, it is advantageous from the viewpoint of maintaining the activity of the catalyst and economic efficiency.

One or two or more types of a carrier may be used. For example, both the transition metal compound and the cocatalyst compound may be supported on one type of a carrier, or the transition metal compound and the cocatalyst compound may be supported on two or more types of a carrier, respectively. In addition, either one of the transition metal compound and the cocatalyst compound may be supported on a carrier.

As a method for supporting the transition metal compound and/or cocatalyst compound that may be used in the catalyst for olefin polymerization, a physical adsorption method or a chemical adsorption method may be used.

For example, the physical adsorption method may be a method of contacting a solution in which a transition metal compound has been dissolved with a carrier and then drying the same; a method of contacting a solution in which a transition metal compound and a cocatalyst compound have been dissolved with a carrier and then drying the same; and a method of contacting a solution in which a transition metal compound has been dissolved with a carrier and then drying the same to prepare the carrier that supports the transition metal compound, separately contacting a solution in which a cocatalyst compound has been dissolved with a carrier and then drying the same to prepare the carrier that supports the cocatalyst compound, and the mixing them.

The chemical adsorption method may be a method of supporting a cocatalyst compound on the surface of a carrier and then supporting a transition metal compound on the cocatalyst compound, or a method of covalently bonding a functional group on the surface of the carrier (e.g., a hydroxyl group (—OH) on the silica surface in the case of silica) with a catalyst compound.

In an embodiment of the present invention, the olefinic polymer may be a homopolymer of an olefinic monomer or a copolymer of an olefinic monomers and an olefic comonomer. Preferably, the olefinic polymer is a copolymer of an olefinic monomer and an olefinic comonomer.

Here, the olefinic monomer is at least one selected from the group consisting of a C_2-20alpha-olefin, a C_1-20diolefin, a C_3-20cycloolefin, and a C_3-20cyclodiolefin.

For example, the olefinic monomer may include ethylene, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, or 1-hexadecene, etc., and the olefinic polymer may include a homopolymer comprising only one olefinic monomer exemplified above or a copolymer comprising two or more of the olefinic monomers exemplified above.

As an exemplary embodiment, the olefinic polymer may be a copolymer of ethylene and a C_3-20alpha-olefin. Preferably, the olefinic polymer may be a linear low density polyethylene wherein the olefinic monomer is ethylene and the olefinic comonomer is 1-hexene.

In this case, the content of ethylene is preferably 55 to 99.9% by weight, and more preferably 90 to 99.9% by weight. The content of the alpha-olefinic comonomer is preferably 0.1 to 45% by weight, and more preferably 0.1 to 10% by weight.

Method for Preparing Olefinic Polymers

According to an embodiment of the present invention, there is provided a method for preparing an olefinic polymer, which includes: obtaining an olefinic polymer by polymerizing an olefinic monomer in the presence of a hybrid catalyst comprising at least one first transition metal compound represented by the following Formula 1; and at least one second transition metal compound selected from a compound represented by the following Formula 2 and a compound represented by the following Formula 3:

[Image Omitted]

M₁, M₂, X, and R₁to R₁₀are as described in the above olefinic polymer section.

As described above, the olefinic polymer prepared by the preparation method according to one embodiment of the present invention has a density of 0.9 to 0.95 g/cm³and satisfies the following Equations 1a and 2a:

224.02×d−86.257<Tm [Equation 1a]

219.64×d−95.767<Tc [Equation 2a]

- wherein Tm is a melting temperature (° C.), Tc is a crystallization temperature (° C.), and d is a density (g/cm³) of the olefinic polymer.

In an embodiment of the present invention, the olefinic polymer satisfies the following Equation 1b and 2b:

Tm<224.02×d−82.257 [Equation 1]

Tc<219.64×d−91.767 [Equation 2]

In an embodiment of the present invention, the olefinic polymer may have (1) a density of 0.918 to 0.945 g/cm³; (2) a melt index (I_2.16) of 0.1 to 5.0 g/10 min under a load of 2.16 kg, when measured at 190° C.; (3) a melt flow ratio (MFR) of 17 or more, when measured at 190° C., as a ratio of the melt index (I_21.6) under a load of 21.6 kg to the melt index (I_2.16) under a load of 2.16 kg; (4) a melting temperature of 120° C. or more; and (5) a crystallization temperature of 107° C. or more.

In an embodiment of the present invention, the olefinic polymer may be polymerized by, for example, polymerization reactions such as free radical, cationic, coordination, condensation, and addition, but it is not limited thereto.

As an example of the present invention, the olefinic polymer may be prepared by gas-phase polymerization method, a solution polymerization method, or a slurry polymerization method. Preferably, the polymerization of the olefinic monomers may be performed by gas-phase polymerization. Specifically, the polymerization of an olefinic monomer may be performed in a gas-phase fluidized bed reactor.

When the olefinic polymer is prepared by a solution polymerization method or a slurry polymerization method, examples of solvents that may be used may include, but are not limited thereto, C_5-12aliphatic hydrocarbon solvents such as pentane, hexane, heptane, nonane, decane, and isomers thereof; aromatic hydrocarbon solvents such as toluene and benzene; hydrocarbon solvents substituted with chlorine atoms such as dichloromethane and chlorobenzene; and mixtures thereof.

Mode for Invention
EXAMPLES

Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples are only for exemplifying the present invention, and the scope of the present invention is not limited only to these.

Preparation Example

A transition metal compound of Formula 1-1 (bis(n-propylcyclopentadienyl) hafnium dichloride) and a transition metal compound of Formula 2-1 (bis(n-butylcyclopentadienyl) zirconium dichloride) were purchased from TCI and used without an additional purification process.

892 g of a toluene solution of 10% methylaluminoxane was added to 4.47 g of the transition metal compound of Formula 1-1 and 1.67 g of the transition metal compound of Formula 2-1, followed by stirring at room temperature for 1 hour. After the reaction, the solution was added to 200 g of silica (XPO-2402), and further 1.5 liters of toluene was added thereto, followed by stirring at 70° C. for 2 hours. The supported catalyst was washed with 500 ml of toluene and dried in a vacuum at 60° C. overnight to obtain 280 g of the supported catalyst in powder form.

Examples 1 to 3

An ethylene/1-hexene copolymer was prepared in the presence of the supported catalyst obtained in Preparation Example 1 in a gas-phase fluidized bed reactor. The partial pressure of ethylene in the reactor was maintained at about 15 kg/cm2, and the polymerization temperature was maintained at 70 to 90° C.

Polymerization conditions of the Examples are shown in Table 1 below.

TABLE 1

Example 1
Example 2
Example 3

Polymerization temperature (° C.)
80.1
80.9
79.9

Catalyst feed amount (g/h)
1.2
1.4
2.0

Hydrogen feed amount (g/h)
2.66
2.34
2.11

1-Hexene feed amount (kg/h)
2.29
1.63
1.37

Ratio of hydrogen/ethylene
0.053
0.048
0.043

concentration (%)

Ratio of 1-hexene/ethylene
2.44
1.99
1.73

concentration (%)

Comparative Example 1

For comparison, linear low-density polyethylene VL0001 (density 0.900 g/cm³, melt index 1.0 g/10 min) from DL Chemical and linear low-density polyethylene M1810HA (density 0.9200 g/cm³, melt index 1.0 g/10 min) from Hanwha Solutions were used.

Test Example

The physical properties of the olefinic polymers prepared in the Examples were measured according to the following methods and standards. The results are shown in Table 2 below.

(1) Density

It was measured in accordance with ASTM D1505.

(2) Melt Index and Melt Flow Ratio (MFR)

The melt index was measured at 190° C. under a load of 21.6 kg and a load of 2.16 kg, respectively in accordance with ASTM D 1238. Their ratio (MI_21.6/MI_2.16) was calculated.

(3) Melting Temperature and Crystallization Temperature

The thermal properties of the resin were measured using a differential scanning calorimeter (DSC). A first endothermic curve was obtained while raising the temperature from 30° C. to 170° C. at 10° C/min. Then, after maintaining the temperature at 170° C. for 5 minutes, an exothermic curve was obtained while decreasing the temperature to −20° C. at 10° C/min. In addition, a second endothermic curve was obtained while raising the temperature from −20° C. to 170° C. at 10° C/min.

TABLE 2

Compara-
Compara-

tive
tive

Example
Example
Example
Example
Example

Unit
1
2
3
1
2

MI_2.16
g/10
0.99
1.06
0.97
1.05
1.01

min

MI_21.16
g/10
24.8
24.9
17.1
17.1
16.6

min

MFR
—
25.1
23.5
17.6
16.3
16.4

Density
g/cm³
0.908
0.918
0.929
0.906
0.920

T_m
° C.
119.2
121.3
123.9
108.3
117

T_c
° C.
105.8
107.6
110.4
92.1
104.2

Crystal-
%
31.9
40.6
45
29.6
42.1

linity

As confirmed from Table 2 and FIGS. 1 and 2 above, the olefinic polymer according to the embodiment of the present invention has high melting temperature and a high crystallization temperature, so that the resin has excellent heat resistance. Therefore, the olefinic polymer according to an embodiment of the present invention may be utilized in spout pouches for high-temperature liquid containers, or the like.

INDUSTRIAL APPLICABILITY

The present invention may provide an olefinic polymer having excellent heat resistance. Therefore, the olefinic polymer according to an embodiment of the present invention may be utilized in spout pouches for high-temperature liquid containers, or the like.