KR102619381B1 - Manufacturing Methods for Highly Active Linear Low Density Polyethylene - Google Patents

Abstract

The present invention relates to a method for producing linear low-density polyethylene with high activity in a hexane slurry process.
The present invention provides a method for producing highly active linear low-density polyethylene, which includes (a) mixing solid methylaluminoxane and a metallocene complex in a hydrocarbon solvent having 4 to 14 carbon atoms and aging to prepare a metallocene catalyst; steps; (b) In order to shorten the retention time of the prepared metallocene catalyst, the metallocene catalyst was activated by reacting in hexane containing alkylaluminum for 0.5 to 5 minutes at 70 to 90°C and ethylene below 1 bar. ordering step; (c) Activated metallocene catalyst, hydrocarbon solvent having 4 to 14 carbon atoms, alkylaluminum, hydrogen, antistatic agent, ethylene, and comonomer are added to the reactor, and solvent slurry polymerization is performed to produce a linear low-density polyethylene slurry. manufacturing step; and (d) removing solvents including low molecules and side reactants by filtration to increase the purity of the linear low-density polyethylene, and separating and drying the linear low-density polyethylene.

Description

{Manufacturing Methods for Highly Active Linear Low Density Polyethylene}

The present invention relates to a method for producing highly active linear low-density polyethylene, and more specifically, to a method for producing linear low-density polyethylene with high activity using a hexane slurry method.

Polyethylene manufactured by coordination polymerization of Ziegler-Nata or metallocene catalysts is broadly classified into high density (HDPE, 0.94 g/cm ³ or more), medium density (MDPE, 0.93-0.94 g/cm 3 ), and linear low density (LLDPE, 0.94 g/cm ^{3 or more} ) depending on density. It can be classified as 0.91~0.93 g/cm ³ ) and very low density (VLDPE, 0.91 g/cm ³ or less).

As is widely known, when polymerizing polyethylene, low-density polyethylene can be produced by adding α-olefins such as 1-butene, 1-hexene, and 1-octene as comonomers. However, low density polyethylene can be produced due to the high comonomer content. Since the solvent-soluble components increase as the polymer increases, it is difficult to manufacture polymers with a density of 0.88 or less, which are classified as POE (polyolefin elastomer), except through a solution process.

However, polyethylene polymers with a density of 0.88 to 0.93 g/cm ³ are being manufactured commercially through gas phase processes or slurry processes due to the development of polymerization technology using metallocene catalysts. In particular, polymerization of polyethylene generally takes 70 days. Polyethylene with a high comonomer content can be produced by lowering the polymerization temperature as much as possible compared to performing it at ℃ or higher.

However, as the polymerization temperature is lowered, there is a problem that the catalyst activity decreases significantly and productivity decreases. In particular, in the hexane slurry process, the higher the comonomer content, the more solvent-soluble components are generated, making it more difficult to produce low-density polyethylene. .

Korean Patent Publication No. 1998-0703683 discloses a method for producing an ethylene copolymer by polymerizing ethylene and a small amount of C ₃ -C ₆ alpha-olefin in particle form in a slurry reactor in the presence of an ethylene polymerization reaction catalyst. A method was disclosed wherein the polymerization reaction is performed in a propane diluent at a temperature of 80° C. or higher, and the catalyst is a metallocene catalyst activated with an alumoxane compound.

Accordingly, the present inventors tried to solve the above problem, and as a result, the retention time of the catalyst was reduced through the process of promoting the activity of the metallocene catalyst, thereby achieving a density of 0.91 to 0.93 g/cm in the hexane slurry method using a CSTR reactor. After confirming that linear low-density polyethylene of ³ can be produced with high activity even at a low polymerization temperature, the present invention was completed.

The purpose of the present invention is to provide a method for producing linear low-density polyethylene with high activity using a hexane slurry method.

In order to achieve the above object, the present invention includes the steps of (a) mixing solid methylaluminoxane and a metallocene complex in a hydrocarbon solvent having 4 to 14 carbon atoms and aging them to prepare a metallocene catalyst; ; (b) In order to shorten the retention time of the manufactured metallocene catalyst, the metallocene catalyst was activated by reacting in hexane containing alkylaluminum for 0.5 to 5 minutes at 70 to 90°C and ethylene below 1 bar. ordering step; (c) Activated metallocene catalyst, hydrocarbon solvent having 4 to 14 carbon atoms, alkylaluminum, hydrogen, antistatic agent, ethylene, and comonomer are added to the reactor, and solvent slurry polymerization is performed to produce a linear low-density polyethylene slurry. manufacturing step; and (d) removing the solvent by filtration and separating and drying the linear low-density polyethylene.

In the present invention, the particle size of the solid methylaluminoxane is 5 to 8㎛, and the molar ratio of the transition metal in the metallocene complex to the aluminum of the solid methylaluminoxane is 1:10 to 1:1000.

In the present invention, the aging is performed for more than 72 hours.

In the present invention, in step (c), polymerization is performed by adding ethylene and one or more comonomers at a temperature of 10 to 60°C, and the comonomers are linear and branched α-olefins with C ₃ to C ₂₀ . , characterized in that it is one or more compounds selected from the group consisting of cyclic olefins, bicycloalkenes, aromatic α-olefin monomers, and derivatives thereof.

In the present invention, polymerization can be carried out in two stages, and the MI (190°C, 2.16 kg) of the linear low-density polyethylene slurry produced in the first stage reaction is 0.1 to 100 and the density is 0.92 to 0.94 g/cm ³ . , The MI (190°C, 21.6 kg) of the linear low-density polyethylene slurry produced in the two-stage reaction is characterized as 0.01 to 10 and the density is 0.90 to 0.92 g/cm ³ .

The present invention can provide a method for producing linear low density polyethylene (LLDPE) with a density of 0.91 to 0.93 g/cm ³ with high activity through a hexane slurry method.

Figure 1 is a chart showing the effect of promoting polymerization rate and catalyst activity according to polymerization temperature.

In the present invention, the retention time of the catalyst is reduced and the maximum polymerization rate is quickly reached through the process of promoting the activity of the metallocene catalyst, thereby producing a linear low density of 0.91 to 0.93 g/cm ³ in the solvent slurry method. We sought to confirm that polyethylene can be produced with high activity even at low polymerization temperatures.

In the present invention, without using a silica carrier, a metallocene catalyst is prepared by mixing solid methylaluminoxane and a metallocene complex, then going through an aging step, and heating the metallocene catalyst in hexane containing alkylaluminum at a specific temperature. After activation by reacting with ethylene under pressure conditions, linear low-density polyethylene was prepared through hexane slurry polymerization at a temperature of 10 to 60°C. In other words, it was confirmed that linear low-density polyethylene could be produced with high activity even at low polymerization temperatures.

Therefore, in one aspect, the present invention relates to (a) mixing solid methylaluminoxane and a metallocene complex in a hydrocarbon solvent having 4 to 14 carbon atoms and aging them to prepare a metallocene catalyst. step; (b) In order to shorten the retention time of the prepared metallocene catalyst, the metallocene catalyst was activated by reacting in hexane containing alkylaluminum for 0.5 to 5 minutes at 70 to 90°C and ethylene below 1 bar. ordering step; (c) Activated metallocene catalyst, hydrocarbon solvent having 4 to 14 carbon atoms, alkylaluminum, hydrogen, antistatic agent, ethylene, and comonomer are added to the reactor, and solvent slurry polymerization is performed to produce a linear low-density polyethylene slurry. manufacturing step; and (d) filtering and removing the solvent from the prepared slurry, and separating and drying the linear low-density polyethylene.

In the present invention, step (a) is a step of preparing a metallocene catalyst, and the particle size of solid methylaluminoxane used in preparing the metallocene catalyst is 5 to 8 ㎛. If the particle size of solid methylaluminoxane is too small, it is difficult to control the heat of reaction during polymerization of linear low-density polyethylene, and the activity is reduced due to poor morphology due to static electricity issues. If it exceeds 8㎛, the activity is very low. there is.

The metallocene compound used in the present invention is a cyclopentadienyl group, a substituted cyclopentadienyl group, an indenyl group, or a substituted indenyl group in which transition metals of group 4 of the periodic table (e.g., titanium, zirconium, hafnium) create an η5 bond. It has a structure in which two of , a fluorenyl group, and a substituted fluorenyl group are combined. Examples of metallocene catalysts include bis(cyclopentadienyl)zirconium dichloride, bis(cyclopentadienyl)zirconium methyl chloride, bis(cyclopentadienyl)zirconium dimethyl, and bis(methylcyclopentadienyl)zirconium dichloride. , bis(methylcyclopentadienyl)zirconium methyl chloride, bis(methylcyclopentadienyl)zirconium dimethyl, bis(ethylcyclopentadienyl)zirconium dichloride, bis(ethylcyclopentadienyl)zirconium methyl chloride, bis( Ethylcyclopentadienyl)zirconium dimethyl, bis(pentamethylcyclopentadienyl)zirconium dichloride, bis(pentamethylcyclopentadienyl)zirconium methyl chloride, bis(pentamethylcyclopentadiethyl)zirconium dimethyl, bis(n-butyl) -Cyclopentadienyl)zirconium dichloride, bis(n-butyl-cyclopentadienyl)zirconium methyl chloride, bis(n-butyl-cyclopentadienyl)zirconium dimethyl, bis(indenyl)zirconium dichloride, bis( Indenyl)zirconium methyl chloride, bis(indenyl)zirconium dimethyl, bis(2-methyl-indenyl)zirconium dichloride, bis(2-methyl-indenyl)zirconium methyl chloride, bis(2-methyl-indenyl) Zirconium dimethyl, bis(2-phenyl-indenyl)zirconium dichloride, bis(2-phenyl-indenyl)zirconium methyl chloride, bis(2-phenyl-indenyl)zirconium dimethyl, dimethylsilylbis(cyclopentadienyl) Zirconium dichloride, dimethylsilibis(cyclopentadienyl)zirconium methyl chloride, dimethylsilylbis(cyclopentadienyl)zirconium dimethyl, dimethylsilylbis(indenyl)zirconium dichloride, dimethylsilibis(indenyl)zirconium methyl Chloride, dimethylsilylbis(indenyl)zirconium dimethyl, dimethylsilylbis(2-methyl-indenyl)zirconium dichloride, dimethylsilylbis(2-methyl-indenyl)zirconium methyl chloride, dimethylsilylbis(2-methyl- Indenyl)zirconium dimethyl, dimethylsilibis(indenylcyclopentadienyl)zirconium dichloride, dimethylsilyl(indenylcyclopentadienyl)zirconium methyl chloride, dimethylsilyl(indenylcyclopentadienyl)zirconium dimethyl, dimethyl Silyl(fluorenylcyclopentadienyl)zirconium dichloride, dimethylsilyl(fluorenylcyclopentadienyl)zirconium methyl chloride, dimethylsilyl(fluorenylcyclopentadienyl)zirconium dimethyl, ethylenebis(cyclopentadienyl) )Zirconium dichloride, ethylenebis(cyclopentadienyl)zirconium methyl chloride, ethylenebis(cyclopentadienyl)zirconium dimethyl, ethylenebis(indenyl)zirconium dichloride, ethylenebis(indenyl)zirconium methyl chloride, ethylenebis (Indenyl)zirconium dimethyl, ethylenebis(2-methyl-indenyl)zirconium dichloride, ethylenebis(2-methyl-indenyl)zirconium methyl chloride, ethylenebis(2-methyl-indenyl)zirconium dimethyl, ethylene ( Indenylcyclopentadienyl)zirconium dichloride, Ethylene (indenylcyclopentadienyl)zirconium methyl chloride, Enylene (indenylcyclopentadienyl)zirconium dimethyl, Ethylene (fluorenylcyclopentadienyl)zirconium dichloride , Ethylene(fluorenylcyclopentadienyl)zirconium methyl chloride, Ethylene(fluorenylcyclopentadienyl)zirconium dimethyl, Isopropylbis(cyclopentadienyl)zirconium dichloride, Isopropylbis(cyclopentadienyl) Zirconium methyl chloride, isopropylbis(cyclopentadienyl)zirconium dimethyl, isopropylbis(indenyl)zirconium dichloride, isopropylbis(indenyl)zirconium methyl chloride, isopropylbis(indenyl)zirconium dimethyl, isopropyl Bis(2-methyl-indenyl)zirconium dichloride, isopropylbis(2-methyl-indenyl)zirconium methyl chloride, isopropyl(2-methyl-indenyl)zirconium dimethyl, isopropyl(indenylcyclopentadienyl) )Zirconium dichlorite, isopropyl(indenylcyclopentadienyl)zirconium methyl chloride, isopropyl(indenylcyclopentadienyl)zirconium dimethyl, isopropyl(fluorenylcyclopentadienyl)zirconium dichloride, isopropyl (Fluorenylcyclopentadienyl)zirconium methyl chloride and isopropyl(fluorenylcyclopentadienyl)zirconium dimethyl, rac-ethylenebis(1-indenyl)zirconium dichloride, rac-ethylenebis(1-indenyl) ) Hafnium dichloride, rac-ethylenebis(1-tetrahydro-indenyl)zirconium dichloride, rac-ethylenebis(1-tetrahydro-indenyl)hafnium dichloride, rac-dimethylsilanediylbis(2-methyl -Tetrahydrobenzidenyl)zirconium dichloride, rac-dimethylsilanediylbis(2-methyl-tetrahydrobenzidenyl)hafnium dichloride, rac-diphenylsilanediylbis(2-methyl-tetrahydrobenz) Nyl) zirconium dichloride, rac-diphenylsilane diylbis(2-methyl-tetrahydrobenzidenyl)hafnium dichloride, rac-dimethylsilane diylbis(2-methyl-4,5-benzidenyl)zirconium dichloride Chloride, rac-dimethylsilanediylbis(2-methyl-4,5-benzidenyl)hafnium dichloride, rac-diphenylsilanediylbis(2-methyl-4,5-benzidenyl)zirconium dichloride Chloride, rac-diphenylsilanediylbis(2-methyl-4,5-benzidenyl)hafnium dichloride, rac-dimethylsilanediylbis(2-methyl-5,6-cyclopentadienylindenyl) Zirconium dichloride, rac-dimethylsilanediylbis(2-methyl-5,6-cyclopentadienylindenyl)hafnium dichloride, rac-diphenylsilanediylbis(2-methyl-5,6-cyclopenta Dienylindyl)zirconium dichloride, rac-diphenylsilanediylbis(2-methyl-5,6-cyclopentadienylindenyl)hafnium dichloride, rac-dimethylsilylbis(2-methyl-4-phenyl indenyl)zirconium dichloride, diethylsilylbis(2-methyl-4-t-butylphenyl-indenyl)zirconium chloride, rac-dimethylsilylbis(2-methyl-4-phenylindenyl)hafnium dichloride, rac -Diphenylsilylbis(2-methyl-4-phenylindenyl)zirconium dichloride, rac-diphenylsilylbis(2-methyl-4-phenylindenyl)hafnium dichloride, etc., but are not limited thereto. .

The molar ratio between the transition metal in the metallocene complex and the aluminum in the solid methylaluminoxane is preferably 1:10 to 1:1000, and more preferably 1:50 to 1:400. If the molar ratio of the transition metal in the metallocene catalyst and the aluminum in the solid methylaluminoxane exceeds 1:10 to 1:1000, that is, if the metallocene complex is excessively added, the increase in activity is small compared to the amount of metallocene used. The unit cost increases, leaching and low molecular weight polymers may increase, and if solid methylaluminoxane is added excessively, the polymer has poor morphology and low activity.

In the present invention, in order to prepare a metallocene catalyst with improved activity and morphology of linear low-density polyethylene, it is preferable to perform aging through support stabilization for 72 hours or more, and less than 72 hours when preparing the metallocene catalyst. When carried out, the activity of linear low density polyethylene is not sufficiently improved, and similar activity is shown even if carried out for more than 72 hours. The aging process is carried out at 15 to 30°C, preferably at room temperature without separate heat energy control. If the temperature is lowered or raised too much, the activity may not be sufficiently improved or may actually decrease. Here, activity refers to the weight of linear low-density polyethylene produced compared to the weight of catalyst introduced.

In the present invention, step (b) is a step of promoting the activation of the metallocene catalyst in order to improve the polymerization activity that decreases when polymerization is performed at a low temperature, and the metallocene catalyst is reacted in hexane containing alkyl aluminum at 70 ~ It is characterized by reacting for 0.5 to 5 minutes under ethylene at 90°C and 1 bar or less.

If the temperature exceeds 70-90°C during the activation promotion reaction, the activity may not be sufficiently improved or may actually decrease. Additionally, if the pressure exceeds 1 bar or the reaction time exceeds 0.5 to 5 minutes, the activity is not sufficiently improved, the bulk density is poor, and properties such as soluble yield, melt index, and Mn/Mw deteriorate. There is a problem.

The metallocene catalyst prepared according to the present invention has a retention time as shown in Figure 1 during polyethylene polymerization. The shorter the delay time, the faster the catalyst can reach the maximum propagation rate. In the process, there is a limit to the polymerization residence time and the catalyst's activity gradually decreases, so reducing the delay time can greatly contribute to improving activity. there is.

As shown in Figure 1, the lower the polymerization temperature, the longer the delay time and the lower the activity, and the shorter the polymerization residence time, the greater this difference. Therefore, in the present invention, where polymerization is performed at a relatively low temperature, the catalyst delay time can be shortened and the activity can be improved to a significant level by performing a catalyst activation promotion process at a high temperature before polymerization.

In the present invention, step (c) is a step of preparing a linear low-density polyethylene slurry through solvent slurry polymerization, wherein alkylaluminum, hydrogen, antistatic agent, ethylene, and one or more comonomers are added to the polymerization reactor to produce hydrocarbon. Slurry polymerization can be performed under a solvent.

At this time, the alkylaluminum has a weight-to-volume of hydrocarbon solvent of 500 ppm or less, the antistatic agent has a weight-to-volume of hydrocarbon solvent of 200 ppm or less, and the molecular weight is adjusted with hydrogen under the conditions of polymerization temperature of 10~60℃ and polymerization pressure of 15 bar or less. It is desirable to do so.

In the present invention, the hydrocarbon solvent may be linear alkanes, cycloalkanes, toluene, xylene, alkyl aromatics such as ethyl benzene, halogenated aromatic solvents such as chlorobenzene, chloronaphthalene, orthodichlorobenzene, etc., but normal It is most preferable to use hexane.

In the present invention, alkylaluminum is added at a weight ratio of 500 ppm or less to the volume of hexane in order to remove hexane and catalyst poison components in the raw materials. If added excessively, there is a problem that the catalyst activity decreases and the inorganic content of the polymer increases. The alkylaluminum used at this time is diethylaluminum chloride (DEAC), ethyl aluminum dichloride (EADC), dinormal butyl aluminum chloride (DNBAC), diisobutyl aluminum chloride (DIBAC), and ethyl aluminum sesquichloride (EASC). , from the group consisting of triethylaluminum (TEA), triisobutylaluminum (TIBA), trinormalhexyl aluminum (TNHA), trinormaloctylaluminum (TNOA), trinormaldecyl aluminum (TNDA), and methylaluminoxane (MAO). At least any one selected may be used, preferably triethylaluminum, but is not limited thereto.

In the present invention, the antistatic agent is added to prevent static electricity, and if the amount added is excessive, the catalyst activity decreases. Antistatic agents include at least one compound selected from the group consisting of glyceryl stearate, glyceryl monostearate, alkylamine, ethoxylated alkylamine, alkylsulfonate, and glyceryl ester, as well as commercially available products such as registered Trademarks such as Armostat, Statsafe, and Atmer may be used, but are not limited thereto.

In the present invention, the comonomer may include C ₃ to C ₂₀ linear and branched α-olefins, cyclic olefins, bicycloalkenes, aromatic α-olefin monomers and derivatives thereof, but is not limited thereto. .

In the present invention, polymerization can be carried out in two stages to control the distribution of comonomers. The MI (190°C, 2.16 kg) of the linear low-density polyethylene slurry produced by the first-stage reaction is 0.1 to 100 and the density is 0.92-0.94 g/cm ³ , and the MI (190°C) of the linear low-density polyethylene slurry produced by the two-stage reaction is , 21.6kg) is preferably 0.01 to 10, and the density is preferably 0.90 to 0.92 g/cm ³ .

In the present invention, step (d) is characterized in that the solvent in the prepared slurry is removed by filtration, and the linear low-density polyethylene is separated and dried.

In the present invention, the filtered solvent can be reused in the polymerization step, thereby reducing process costs.

[Example]

Hereinafter, the present invention will be described in more detail through examples. These examples are only for illustrating the present invention, and it will be apparent to those skilled in the art that the scope of the present invention is not to be construed as limited by these examples.

Example 1: Production of linear low-density polyethylene using metallocene catalyst and hexane slurry method

1-1: Preparation of metallocene catalyst

After dispersing a magnetic bar and 5.7㎛ particle size solid methylaluminoxane and hexane in a 1L glass bottle from which moisture was completely removed under a nitrogen purge, 4g of rac-ethylenebis(1-tetrahydro-indenyl)zirconium dichloride was added at room temperature. It was added and reacted for 6 hours, and aged for 3 days to prepare a metallocene catalyst. At this time, the molar ratio of Al of solid methylaluminoxane and Zr of rac-ethylenebis(1-tetrahydro-indenyl)zirconium dichloride, that is, the Al/Zr molar ratio, was used to be 200.

1-2: Promote catalyst activation

A magnetic bar, 100 ml of hexane, 50 mg of triethyl aluminum, and 500 mg of the catalyst prepared in 1-1 were sequentially added to a 200 ml glass bottle from which moisture was completely removed under a nitrogen purge, then the temperature was raised to 80°C and stirred for 3 minutes under 0.3 bar of ethylene. did. After the glass bottle was cooled and the pressure was reduced, the catalyst was immediately added to 1-3.

1-3: Preparation of linear low-density polyethylene slurry via hexane slurry polymerization

After sufficiently replacing the 2L autoclave reactor with nitrogen, 1L of hexane, 200mg of triethyl aluminum, 10mg of StatSafe 3000, and 10mg of the catalyst prepared in 1-2 were added.

Using a Mass Flow Controller, polymerization was performed at 30°C for 80 minutes by injecting 2.0L of ethylene per minute and 2.0mL of hydrogen per minute. At the same time, using a metering pump, 1-Butene was added at a ratio of 12wt% compared to the total monomers. , linear low-density polyethylene was produced.

1-4: Preparation of high-purity linear low-density polyethylene through solvent separation and drying

After polymerization was completed, unreacted gas was removed, the pressure was reduced, and 100 ml of methanol was added. The slurry was filtered and dried to obtain linear low density polyethylene.

Example 2: Production of linear low-density polyethylene using metallocene catalyst and hexane slurry method

Linear low-density polyethylene was obtained in the same manner as Example 1, except that in Examples 1-3, the polymerization temperature was adjusted to 50°C and the 1-Butene input ratio was adjusted to 10wt%.

Examples 3-4: Production of linear low-density polyethylene using metallocene catalyst and hexane slurry method

Linear low-density polyethylene was obtained in the same manner as in Example 1, except that the catalyst activation temperature in Examples 1-2 was adjusted to 70 and 90° C., respectively.

Example 5: Production of linear low-density polyethylene using metallocene catalyst and hexane slurry method

In Example 1-1, the same as Example 1 except that ethylenebis(1-indenyl)zirconium dichloride was used as the metallocene complex instead of ethylenebis(1-tetrahydro-indenyl)zirconium dichloride. Linear low-density polyethylene was obtained by this method.

Comparative Examples 1 to 3: Production of linear low-density polyethylene with or without catalyst activation

Except that the catalyst activation in Example 1-2 was not performed and the polymerization temperature was adjusted to 30/50/70°C and the 1-Butene input amount was adjusted to 12/10/9 wt% in Example 1-3, respectively. Linear low-density polyethylene was obtained in the same manner as in Example 1.

Comparative Examples 4-5: Production of linear low-density polyethylene according to catalyst activation conditions

Linear low-density polyethylene was obtained in the same manner as in Example 1, except that the catalyst activation temperature in Examples 1-2 was adjusted to 50 and 100°C, respectively.

Comparative Examples 6-7: Production of linear low-density polyethylene according to catalyst activation conditions

When activating the catalyst of Example 1-2, at 80°C and 3 bar for 10 minutes (Comparative Example 6); Linear low-density polyethylene was obtained in the same manner as in Example 1, except that the process was carried out at 80°C and 0.3 bar for 10 minutes (Comparative Example 7).

Comparative Example 8: Production of linear low-density polyethylene according to particle size of solid methylaluminoxane

Linear low-density polyethylene was obtained in the same manner as in Example 1, except that solid methylaluminoxane with a particle size of 9.2 ㎛ was used in Example 1-1.

Experiment example

The polymerization results and analysis results of Examples and Comparative Examples are shown in Table 1.

(1) Catalytic activity: Weight of the produced linear low-density polyethylene polymer compared to the amount of catalyst introduced (g)

(2) Bulk Density (BD): After filling a cylinder with a volume of 100 mL with powder up to the mark, the amount of powder per volume was calculated.

(3) Soluble Yield: After measuring the total mass (A) of the filtered hexane, a portion (B) was placed in a crucible and placed in an oven at 100°C to dry all the hexane. After drying and cooling sufficiently, the remaining polymer content was measured (C) and calculated using the formula below along with the amount of polymerized PWD (D).

Soluble Yield = [ (C) / (B) x (A)] / [ (C) + (D)] x 100%

(4) Melt Index: Analysis was conducted at 190°C and a load of 2.16 kg according to the ASTM D1238 method.

(5) Mw/Mn: Measure the weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer using gel permeation chromatography (GPC), then divide Mw by Mn to determine the molecular weight distribution (Mw). /Mn) was calculated.

(6) Density: After producing a sheet by extrusion, the density was analyzed according to ASTM D1505.

Sample Step 2
condition Step 3
polymerization temperature 1-C ₄
Feed (wt%) Activity
(g/g) Bulk Density (g/cm ³ ) Solubble
Yield
(%) Melt
Index
(2.16kg) Mw/Mn
(GPC) Density
(g/ ^cm3 ) Example 1 80℃ 30℃ 12 7,300 0.38 2.01 7.4 4.0 0.920 Example 2 80℃ 50℃ 10 11,200 0.36 3.51 3.6 3.4 0.915 Example 3 70℃ 30℃ 12 5,600 0.38 2.00 7.5 4.0 0.922 Example 4 90℃ 30℃ 12 5,100 0.36 2.10 7.4 4.0 0.922 Example 5 80℃ 30℃ 12 8,200 0.37 2.21 6.7 4.7 0.921 Comparative Example 1 Not implemented 30℃ 12 1,400 - - - - - Comparative Example 2 Not implemented 50℃ 10 4,600 0.30 3.44 3.4 3.6 0.918 Comparative Example 3 Not implemented 70℃ 9 Swelling 4.5 3.7 0.924 Comparative Example 4 50℃ 30℃ 12 3,600 0.34 2.28 6.8 5.0 0.920 Comparative Example 5 100℃ 30℃ 12 <1,000 - - - - - Comparative Example 6 80℃
(10 minutes/3bar) 30℃ 12 5,500 0.25 3.10 11 5.3 0.926 Comparative Example 7 80℃ (10 minutes/0.3bar) 30℃ 12 4,100 0.33 2.68 10 4.8 0.925 Comparative Example 8 80℃ 30℃ 12 4,300 0.36 2.21 7.8 4.1 0.921

From Table 1, in the case of Examples 1 to 5, linear low density polyethylene with a density of 0.91 to 0.93 g/cm ³ could be manufactured with high activity even at a low polymerization temperature compared to Comparative Examples 1 and 2 without catalyst activation. .

In Comparative Example 3, it was found that, like general PE polymerization, a swelling phenomenon occurred when LLDPE was polymerized at a polymerization temperature of 70°C or higher.

In Comparative Examples 4 to 5, it was confirmed that when the temperature of the catalyst activation step was too low or too high, the activity was not sufficiently improved or rather decreased.

In Comparative Examples 6 to 7, if the time and pressure conditions of the catalyst activation step are not appropriate, the activity is not sufficiently improved, the bulk density is poor, and the Soluble Yield, Melt Index, and Mn/Mw values increase. There was.

In Comparative Example 8, it was confirmed that the activity was low when the catalyst particle size was not appropriate.

As the specific parts of the present invention have been described in detail above, it is clear to those skilled in the art that these specific techniques are merely preferred embodiments and do not limit the scope of the present invention. will be. Accordingly, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims (5)

(a) mixing solid methylaluminoxane and a metallocene complex in a hydrocarbon solvent having 4 to 14 carbon atoms and aging them to prepare a metallocene catalyst;
(b) In order to shorten the retention time of the manufactured metallocene catalyst, the metallocene catalyst was activated by reacting in hexane containing alkylaluminum for 0.5 to 5 minutes at 70 to 90°C and ethylene below 1 bar. ordering step;
(c) Activated metallocene catalyst, hydrocarbon solvent having 4 to 14 carbon atoms, alkylaluminum, hydrogen, antistatic agent, ethylene, and comonomer are added to the reactor, and solvent slurry polymerization is performed to produce a linear low-density polyethylene slurry. manufacturing step; and
(d) A method for producing linear low-density polyethylene, comprising the steps of filtering and removing the solvent from the prepared slurry, and separating and drying the linear low-density polyethylene.
The linear method of claim 1, wherein the particle size of the solid methylaluminoxane is 5 to 8㎛, and the molar ratio of the transition metal in the metallocene complex to aluminum in the solid methylaluminoxane is 1:10 to 1:1000. Method for producing low-density polyethylene.
The method of claim 1, wherein the aging is performed for 72 hours or more.
The method of claim 1, wherein in step (c), polymerization is performed by adding ethylene and one or more comonomers at a temperature of 10 to 60°C, and the comonomers are C ₃ to C ₂₀ linear, branched α- A method for producing linear low-density polyethylene, characterized in that it is one or more compounds selected from the group consisting of olefins, cyclic olefins, bicycloalkenes, aromatic α-olefin monomers, and derivatives thereof.
According to claim 4, the polymerization can be carried out in two stages, and the MI (190°C, 2.16 kg) of the linear low-density polyethylene slurry produced in the first stage reaction is 0.1 to 100 and the density is 0.92 to 0.94 g/cm ³ A method for producing linear low-density polyethylene, characterized in that the MI (190°C, 21.6 kg) of the linear low-density polyethylene slurry produced by the two-stage reaction is 0.01 to 10 and the density is 0.90 to 0.92 g/cm ³ .