KR101892918B1 - polyethylene for pipe having high pressure resistant and preparation method thereof - Google Patents

Abstract

TECHNICAL FIELD The present invention relates to a polyethylene for a pipe having excellent pressure resistance characteristics, which is produced by a multistage polymerization, and a method for producing the same. More specifically, the present invention relates to a method for producing a polyethylene for a pipe using a metallocene catalyst comprising a solid polymethylaluminoxane and a metallocene compound, The present invention relates to a polyethylene resin composition for pipes, which comprises the produced high density homopolyethylene and a low density polyethylene copolymer and has excellent withstand pressure characteristics, and a pipe using the same.

Description

BACKGROUND OF THE INVENTION Field of the Invention [0001] The present invention relates to a polyethylene for pipes,

TECHNICAL FIELD The present invention relates to a polyethylene for a pipe having excellent pressure resistance characteristics, which is produced by a multistage polymerization, and a method for producing the same. More specifically, the present invention relates to a method for producing a polyethylene for a pipe using a metallocene catalyst comprising a solid polymethylaluminoxane and a metallocene compound, The present invention relates to a polyethylene resin composition for pipes, which comprises the produced high density homopolyethylene and a low density polyethylene copolymer and has excellent withstand pressure characteristics, and a pipe using the same.

High pressure pipes are used to transport liquids and gases such as water and natural gas. Polymers, especially high density polyethylene, are widely used as the main raw material. This is because it is highly resistant to the pressure generated during transport of the fluid and the wide variable temperature of the fluid, is highly resistant to corrosion, is lightweight, and can be easily molded. High-density polyethylene used as a raw material for high-pressure pipes is classified according to the MRS (Minimum Required Strength) value of ISO-12162. The maximum permissible pressure at 20 ° C at 50 years is calculated to calculate the MRS value. The PE63 with a maximum permissible pressure of 6.3 Mpa was first developed in 1960, Is widely used. However, it is still difficult to apply PE100 to water pipes and water pipes which require higher withstand pressure characteristics. To overcome this problem, research on the development of PE125 (maximum allowable pressure of 12.5 Mpa), which has excellent pressure resistance characteristics, has been actively conducted.

US 7,127,853 discloses a technique for improving the sagging phenomenon occurring when the PE 100 is extruded, but does not satisfy the requirement of PE 125. US 2007/0282067 also discloses a technique for improving the sagging of PE100 in which a low molecular weight (LMW) ethylene copolymer and a high molecular weight (HMW) homopolyethylene are multimodally constituted It does not satisfy the requirement of PE125. WO 2014/095917 discloses a technique for resin produced by blending high density multimodal polyethylene with UHMWPE for the development of PE125 pipe resins, but it has been disclosed that high density, multimodal polyethylene and UHMWPE There is a problem that the extrusion must be repeated several times due to the problem of kneading with the resin.

The present inventors have found that when a high density homopolyethylene and a low density polyethylene are continuously and continuously polymerized in different slurry reactors by using a metallocene catalyst in which a solid polymethylaluminoxane and a metallocene compound are bonded to each other, It was found that a resin can be produced, and thus the present invention has been accomplished.

It is an object of the present invention to provide a method of continuously polymerizing high-density homopolyethylene and low-density polyethylene in different slurry reactors using a metallocene catalyst in which solid polymethylaluminoxane and metallocene compound are combined, And a method for producing the same.

It is still another object of the present invention to provide a polyethylene resin for pipes excellent in withstand pressure characteristics produced by the production method according to the present invention.

Another object of the present invention is to provide a polyethylene pipe having excellent pressure resistance characteristics using the polyethylene resin according to the present invention.

In order to achieve the above object,

Mixing a solid polymethyl aluminoxane composition particle, a metallocene compound, an antistatic agent, and a hydrocarbon solvent having carbon atoms of 4 to 14 carbon atoms to prepare a slurry (step 1);

(Step 2) of polymerizing the slurry, the organoaluminum compound, the hydrocarbon solvent having carbon atoms of 4 to 14 carbon atoms, the ethylene monomer and hydrogen produced in step 1, and stirring the high-density homopolyethylene;

Polymerizing the low density polyethylene by mixing and stirring the ethylene monomer and the comonomer with the high density homopolyethylene produced in the step 2 (step 3); And

And filtering and drying the obtained polyethylene (step 4). The present invention also provides a method for producing a polyethylene resin for pipes.

In addition,

The density fraction of the high density homopolyethylene is 35 to 65 wt%, the fraction of the low density polyethylene is 35 to 65 wt%, the melt index flow at 190 DEG C and 5 kg is 0.01 to 1.0 g / 10 min, the density is 0.940 to 0.960, And a molecular weight distribution of from 20 to 50 as measured by a differential scanning calorimeter.

In addition,

A pipe formed body made of a polyethylene resin according to the present invention having excellent pressure resistance characteristics is provided.

The present invention relates to a method of polymerizing high density homopolyethylene and low density polyethylene continuously in different slurry reactors by using a metallocene catalyst in which solid polymethylaluminoxane and metallocene compound are bonded to produce polyethylene for pipes having excellent pressure resistance characteristics can do.

Particularly, as a result of applying the test stress at 20 캜 and evaluating the time taken for the pipe to be broken, the pipe formed of the polyethylene resin produced according to the present invention exhibits excellent pressure resistance creep and can be used as a pipe for gas pipes, Can be usefully used.

Hereinafter, the present invention will be described in detail.

The present invention

Mixing a solid polymethyl aluminoxane composition particle, a metallocene compound, an antistatic agent, and a hydrocarbon solvent having carbon atoms of 4 to 14 carbon atoms to prepare a slurry (step 1);

(Step 2) of polymerizing the slurry, the organoaluminum compound, the hydrocarbon solvent having carbon atoms of 4 to 14 carbon atoms, the ethylene monomer and hydrogen produced in step 1, and stirring the high-density homopolyethylene;

Polymerizing the low density polyethylene by mixing and stirring the ethylene monomer and the comonomer with the high density homopolyethylene produced in the step 2 (step 3); And

And filtering and drying the obtained polyethylene (step 4). The present invention also provides a method for producing a polyethylene resin for pipes.

Specifically, as the particles of the solid polyaluminoxane composition, solid polyaluminoxane particles obtained by mixing a polymethylaluminoxane composition solution containing polymethylaluminoxane and trimethylaluminum with an aromatic hydrocarbon solvent and heating the particles may be used.

At this time, it is preferable that the molar fraction of the methyl group derived from the trimethylaluminum is 15 mol% or less relative to the total number of moles of the methyl group in the polymethylaluminoxane composition solution, and as the molar fraction of the methyl group derived from the trimethyl aluminum segment increases, And it is more preferable that it is contained in an amount of 12 mol% or less because the particles tend to be easily broken.

The polymethylaluminoxane composition solution may be a solution obtained by thermally decomposing an aluminum compound having Al-O-C bonds at 30 DEG C to 80 DEG C for 5 to 100 hours.

The aluminum compound having an Al-OC bond can be prepared by reacting trimethyl aluminum with an organic compound containing oxygen. The molar ratio of the aluminum atom contained in the trimethyl aluminum to the oxygen atom of the organic compound containing oxygen Is in the range of 1: 0.5 to 3.

The organic compound containing oxygen may be, for example, a carboxylic acid compound having a carboxy group or a carboxylic acid anhydride, and specifically includes formic acid, acetic acid, propionic acid, n-butyric acid, n- valeric acid, There may be mentioned acid addition salts such as acetic acid, n-stearic acid, oxalic acid, malonic acid, succinic acid, glutaric acid adipic acid benzoic acid phthalic acid citric acid tartaric acid lactic acid malic acid toluene acid toluene anhydride acetic anhydride propionic anhydride oxalic anhydride, Malonic acid anhydride, malonic acid anhydride, succinic anhydride, but is not limited thereto.

The aromatic hydrocarbon solvent may be at least one material selected from the group consisting of benzene, toluene, ethylbenzene, propylbenzene, butylbenzene, xylene, chlorobenzene, and dichlorobenzene, but is not limited thereto.

In the present invention, since the solid polymethylaluminoxane composition particles are used, metallocene is not required to be supported on the carrier, so that generation of impurities is minimized, and thus it is possible to produce a high-purity polyetherimine. In addition, It is possible to manufacture polyolefin quickly because it is simple to manufacture due to no need for a topical introduction procedure, and can reduce manufacturing cost.

In the above production process, the step of preparing the catalyst of the step 1) may be carried out in two steps of stirring the solid polymethylaluminoxane composition particles and antistatic agent in a hydrocarbon solvent, reacting them, and then adding metallocene.

The hydrocarbon solvent may be a hydrocarbon solvent having carbon atoms of 4 to 14 carbon atoms and may be at least one compound selected from the group consisting of pentane, hexane, cyclohexane, methylcyclohexane, heptane, octane, decane and isopentane However, the present invention is not limited thereto.

When the antistatic agent is used in the catalyst preparation step as described above, it is possible to improve the aggregation phenomenon due to the localized catalyst agglomeration or the excessive chain growth, and it is more effective to increase the molecular weight and to improve the aggregation phenomenon than to use the antistatic agent in the polymerization step great.

Further, since the preparation of the catalyst is carried out in two stages while using an antistatic agent, it is possible to exhibit a more excellent effect of improving the aggregation phenomenon than in the case of using only the antistatic agent in the polymerization.

As the antistatic agent, at least one compound selected from the group consisting of glyceryl stearate, glyceryl monostearate, alkyl amine, ethoxylated alkyl amine, alkyl sulfonate and glyceryl ester may be used, It is not.

A registered trademark Armostat, Statsafe or Atmer, which is a commercially available antistatic agent, may be used, and Stat SAFE 3000 is most preferably used.

The antistatic agent is preferably contained in an amount of 10 parts by weight to 50 parts by weight based on 100 parts by weight of the solid polymethylaluminoxane composition particles. If the antistatic agent is contained in an amount of less than 10 parts by weight, it can not inhibit local catalyst aggregation or excessive chain growth, And if it is contained in an amount exceeding 50 parts by weight, the activity of the solid polymethylaluminoxane composition and the metallocene catalyst is reduced to generate a low molecular weight polymer and inhibit the insertion of olefins.

The metallocene may be added so that the molar ratio of the transition metal in the metallocene to the aluminum in the solid polymethylaluminoxane composition particles is 150: 1 to 600: 1.

If the metallocene catalyst is excessively added to the molar ratio, there is a problem that the amount of increase in activity relative to the amount of metallocene used is small and a low molecular weight polymer is generated. On the other hand, when the solid polymethyl aluminoxane composition particles are excessively added, There is a problem of reducing morphology.

The metallocene compound used in the present invention is a metallocene compound having a cyclopentadienyl group, a substituted cyclopentadienyl group, an indenyl group, a substituted indenyl group, a substituted indenyl group, or a substituted indenyl group in which a transition metal of Group 4 of the periodic table (for example, titanium, zirconium, , A fluorenyl group, and a substituted fluorenyl group. Examples of the metallocene catalyst include bis (cyclopentadienyl) zirconium dichloride, bis (cyclopentadienyl) zirconium methyl chloride, bis (cyclopentadienyl) zirconium dimethyl, bis (methylcyclopentadienyl) zirconium dichloride (Ethylcyclopentadienyl) zirconium dichloride, bis (ethylcyclopentadienyl) zirconium methylchloride, bis (methylcyclopentadienyl) zirconium dichloride, bis Bis (pentamethylcyclopentadienyl) zirconium dimethyl chloride, bis (pentamethylcyclopentadienyl) zirconium dimethyl, bis (pentamethylcyclopentadienyl) zirconium dichloride, bis -Cyclopentadienyl) zirconium dichloride, bis (n-butyl-cyclopentadienyl) zirconium methylchloride Zirconium dichloride, bis (indenyl) zirconium methyl chloride, bis (indenyl) zirconium dimethyl, bis (2-methyl-indenyl) zirconium dichloride, bis ) Zirconium dichloride, bis (2-methyl-indenyl) zirconium dichloride, bis (2-phenyl- indenyl) zirconium dichloride, bis (Cyclopentadienyl) zirconium dichloride, dimethylsilylbis (cyclopentadienyl) zirconium methylchloride, dimethylsilylbis (cyclopentadienyl) zirconium dichloride, (Indenyl) zirconium dimethyl, dimethylsilylbis (indenyl) zirconium dichloride, dimethylsilyl (indenyl) zirconium methyl chloride, dimethylsilyl (indenyl) zirconium dimethyl, dimethyl Zirconium dichloride, dimethylsilylbis (2-methyl-indenyl) zirconium methylchloride, dimethylsilylbis (2-methyl-indenyl) zirconium dimethyl, dimethylsilylbis Zirconium dichloride, dimethylsilyl (indenyl cyclopentadienyl) zirconium dichloride, dimethylsilyl (indenylcyclopentadienyl) zirconium dimethyl, dimethylsilyl (fluorenylcyclopentadienyl) zirconium dichloride (Cyclopentadienyl) zirconium dichloride, ethylene bis (cyclopentadienyl) zirconium dichloride, dimethylsilyl (fluorenylcyclopentadienyl) zirconium dichloride, Zirconium methyl chloride, ethylene bis (cyclopentadienyl) zirconium dimethyl, ethylene bis (indenyl) zirconium dichloride, ethyl (2-methyl-indenyl) zirconium dichloride, ethylene bis (indenyl) zirconium methyl chloride, ethylene bis (indenyl) zirconium dimethyl, ethylene bis (Indenyl cyclopentadienyl) zirconium dichloride, ethylene (indenyl cyclopentadienyl) zirconium methyl chloride, ethylene (indenyl cyclopentadienyl) zirconium dimethyl, ethylene (Cyclopentadienyl) zirconium dichloride, ethylene (fluorenylcyclopentadienyl) zirconium dichloride, ethylene (fluorenylcyclopentadienyl) zirconium dichloride, ethylene (fluorenylcyclopentadienyl) (Cyclopentadienyl) zirconium methyl chloride, isopropyl bis (cyclopentadienyl) zirconium di (Indenyl) zirconium dichloride, isopropyl bis (indenyl) zirconium methyl chloride, isopropyl bis (indenyl) zirconium dimethyl, isopropyl bis (indenyl) zirconium dichloride, isopropyl (Indenyl cyclopentadienyl) zirconium dichloride, isopropyl (indenyl cyclopentadienyl) zirconium dichloride, isopropyl (2-methyl-indenyl) zirconium dichloride, Isopropyl (fluorenylcyclopentadienyl) zirconium dichloride, isopropyl (fluorenylcyclopentadienyl) zirconium methyl chloride and iso (cyclopentadienyl) zirconium dichloride, Ethylene bis (1-indenyl) zirconium dichloride, rac-ethylene bis (1-indenyl) zirconium dichloride, dimethyl (cyclopentadienyl) Ethylenebis (1-tetrahydro-indenyl) hafnium dichloride, rac-dimethylsilanediylbis (1-tetrahydroindenyl) zirconium dichloride, rac- Methyl-tetrahydrobenzenylidene) zirconium dichloride, rac-dimethylsilanediylbis (2-methyl-tetrahydrobenzenylenyl) hafnium dichloride, rac-diphenylsilandiylbis (2-methyl-tetrahydrobenzenylenyl) hafnium dichloride, rac-dimethylsilanediylbis (2-methyl-4,5-benzindenyl) zirconium dichloride, rac-diphenylsilandiylbis ) Zirconium dichloride, rac-dimethylsilanediylbis (2-methyl-4,5-benzindenyl) hafnium dichloride, rac-diphenylsilandiylbis (2-methyl- ) Zirconium dichloride, rac-diphenylsilandiylbis (2-methyl-4,5-benzindenyl) (2-methyl-5,6-cyclopentadienylindenyl) zirconium dichloride, rac-dimethylsilanediylbis (2-methyl-5,6-cyclopentadienyl) zirconium dichloride, Diphenylsilanediylbis (2-methyl-5,6-cyclopentadienylindenyl) zirconium dichloride, rac-diphenylsilanediylbis (2-methyl- (6-cyclopentadienylindenyl) hafnium dichloride, rac-dimethylsilylbis (2-methyl-4-phenylindenyl) zirconium dichloride, rac-dimethylsilylbis Diphenylsilylbis (2-methyl-4-phenylindenyl) zirconium dichloride, rac-diphenylsilylbis (2-methyl-4-phenylindenyl) hafnium dichloride and the like.

In the above production process, the step 2) comprises: polymerizing the slurry, the organoaluminum compound, the hydrocarbon solvent having carbon atoms of 4 to 14 carbon atoms, the ethylene monomer and hydrogen prepared in the step 1, and stirring the high-density homopolyethylene .

The organoaluminum compound is preferably contained in an amount of 300 to 2000 parts by weight based on 100 parts by weight of the slurry. If the organoaluminum compound is contained in an amount of less than 300 parts by weight, the bulk density of the polymer is lowered. If the organoaluminum compound is contained in an amount exceeding 2000 parts by weight, the content of the polymer may increase.

The organoaluminum compound is _{Al (C 2 H 5) 3} , Al (C 2 H 5) 2 H, Al (C 3 H 7) 3, Al (C 3 H 7) 2 H, Al (iC 4 H 9) _{2 H, Al (C 8 H} 17) 3, Al (C 12 H 25) 3, Al (C 2 H 5) (C 12 H 25) 2, Al (iC 4 H 9) (C 12 H 25) 2 , At least one compound selected from the group consisting of Al (iC ₄ H ₉ ) ₃ , (C ₂ H ₅ ) ₂ AlCl, (iC ₃ H ₉ ) ₂ AlCl and (C ₂ H ₅ ) ₃ Al ₂ Cl ₃ desirable.

The hydrocarbon solvent may be used for a hydrocarbon having a carbon atom of 4 to 14 carbon atoms, for example, at least one compound selected from the group consisting of pentane, hexane, cyclohexane, methylcyclohexane, heptane, octane, decane and isopentane But is not limited thereto.

The step 2 polymerization can be carried out at 60 to 90 占 폚, 3 to 15 bar for 1 to 4 hours.

The prepolymerization can be carried out for a short time at a mild temperature and low pressure condition before carrying out the polymerization step, preferably at 20 ° C to 50 ° C, at 0.1 to 2 bar for 30 minutes to 2 hours.

When prepolymerization is carried out under the above conditions, a prepolymer of 0.2 to 10 g-polymer / g-catalyst can be produced. By performing the prepolymerization under the above conditions, polymerization heat control of the product polyethylene is possible, Can be mitigated.

The high density homopolyethylene produced in the step 2 preferably has a melt flow rate of 300 to 5000 g / 10 min at 190 DEG C and 2.16 kg, and a density of 0.970 or more. When the melt flow rate is lower than 300 g / 10 min, the pressure resistance characteristic of the manufactured polyethylene pipe is insufficient. When the melt flow rate is higher than 5000 g / 10 min, the melt flow rate of the polyethylene resin produced at 190 캜 and 5 kg is 1.0 g / 10 min So that sagging occurs when the pipe is formed.

In the above production method, the step 3) comprises polymerizing the low density polyethylene by mixing and stirring the high density homopolyethylene produced in the step 2 with the ethylene monomer and the comonomer.

The comonomer may be one or more compounds selected from the group consisting of butene, hexene, methylpentene, and octene for controlling the density.

The low density polyethylene produced in the step 3 preferably has a melt flow rate of 0.01 to 0.30 g / 10 min at 190 DEG C and 21.6 kg and a density of 0.912 to 0.930.

The above step 3 polymerization can be carried out at 50 ° C to 90 ° C, 1 bar to 15 bar for 1 hour to 4 hours.

In the above production method, the step (4) includes filtering and drying the obtained polyethylene.

The polyethylene resin produced through the step 4 had a high density homopolyethylene fraction of 35 to 65 wt% and a low density polyethylene fraction of 35 to 65 wt%, and a melt index flow at 190 DEG C and 5 kg of 0.01 to 1.0 g / 10 Min, a density of 0.940 to 0.960, and a molecular weight distribution as measured by GPC of 20 to 50.

After filtration in step 4, the solvent is recovered and purified to recover the minor reactant containing the low molecular weight component, and the remaining solvent can be reused as the solvent of step 1.

The low-molecular component adversely affects the physical properties of the pipe-shaped body as a polymerization side reaction material, and therefore, it is possible to improve the internal pressure creep.

Also, the present invention provides a polyethylene resin for pipes excellent in withstand pressure characteristics produced by the production method according to the present invention.

The polyethylene resin has a high density homopolyethylene fraction of 35 to 65 wt% and a low density polyethylene fraction of 35 to 65 wt%. The polyethylene resin has a melt index of 0.01 to 1.0 g / 10 min at 190 캜 and 5 kg, a density of 0.940 To 0.960, and the molecular weight distribution measured by GPC may have a value of 20 to 50. [

In addition, the present invention provides a pipe formed from the polyethylene resin according to the present invention.

A pipe having excellent pressure resistance characteristics manufactured according to the present invention can have a pressure resistance characteristic that is not broken within 100 hours at 20 DEG C and 14.5 MPa and within 1000 hours at 20 DEG C and 13.7 MPa.

Also, since the polyethylene resin according to the present invention is produced through a production method including a process of removing a low-molecular component, the low-molecular component can adversely affect the physical properties of the pipe-shaped body as a polymerization side reaction material and can improve the internal pressure creep.

The polyethylene resin according to the present invention may further contain antioxidants, pigments for color formulations, processing aids, and the like in accordance with the end use. As the antioxidant, a phenol-based antioxidant is mainly used for the purpose of preventing thermal oxidation when passing through an extruder and for improving the long-term thermal oxidation resistance, a usual carbon black master batch is used as a pigment for color prescription, A fluorine-based resin can be used for improving processability.

Since the polyethylene resin according to the present invention has excellent pressure resistance characteristics, it can be applied to the pipes for water pipes, gas pipes and water pipes during pipe forming.

Hereinafter, preferred embodiments of the present invention will be described in detail.

The embodiments described herein are preferred embodiments of the present invention and are not intended to represent all of the technical ideas of the present invention, so that various equivalents and modifications may be substituted for them at the time of application of the present invention.

<Method>

(One) Melt flow  Indices

The melt flow index is a flow rate when a polymer melt is extruded from a piston under a predetermined constant condition (190 DEG C for polyethylene), which is an index indicating the ease of flow of the melt, measured according to ASTM D1238 and expressed in g / . Depending on the weight of the load applied, a melt flow index of 2.16 kg, 5 kg and 21.6 kg can be obtained.

(2) Density

The density of the polymer is measured according to ASTM D1505 and shown as kg / m ^3.

(3) Molecular weight distribution

The molecular weight distribution (Mw / Mn) is calculated by measuring Mw and Mn using Gel Permeation Chromatography (GPC).

&Lt; Example 1 >

(1) Preparation of metallocene catalyst

To a 500 ml glass bottle in which the water had been completely removed, a magnet bar, 250 ml of hexane, 1 g of solid polymethylaluminoxane and 0.2 g of Stat SAFET 3000 were added and stirred for 30 minutes at 30 ° C so that the obtained Al / Zr ratio became 300 (Dimethylsilylbis (2-methyl-indenyl) zirconium dichloride was added, and the mixture was stirred at 30 ° C for 30 minutes.

(2) Production of polyethylene for pipes having excellent pressure resistance characteristics

A 50 L high-pressure reactor equipped with a magnetic stirrer was thoroughly purged with nitrogen, and 25 L of hexane, 10 g of triethylaluminum and 1 g of a slurry catalyst were added successively. After the nitrogen in the gaseous phase was removed by using a vacuum pump, the temperature was raised to 65 ° C by flowing steam through the jacket of the high-pressure reactor. Steam was then closed and ethylene and hydrogen were continuously added using MFC (mass flowmeter controller) Lt; 0 &gt; C and polymerized for 90 minutes to polymerize the high density homopolyethylene. At this time, the charging ratio of ethylene and hydrogen charged was 1: 0.006 (L / min: L / min). The high-density homopolyethylene had a melt flow rate of 2,400 g / 10 min at 190 DEG C and 2.16 kg and a density of 0.970.

The prepared high density homopolyethylene was transferred to a 50 L high pressure reactor for low density polyethylene polymerization using pressure and then removed all unreacted hydrogen and ethylene present in the gaseous phase. The temperature was raised to 55 ° C by flowing steam through the jacket of the high-pressure reactor, the steam was shut off, ethylene was continuously added using a mass flowmeter controller (MFC), and 1-octene was continuously introduced by using a metering pump. Deg.] C for 60 minutes to polymerize the low density polyethylene. At this time, the charging ratio of ethylene and octene charged was 1: 0.00015 (L / min: L / min).

After completion of the polymerization, the temperature of the reactor was lowered to room temperature, unreacted gas was removed, and the polyethylene was filtered and dried to obtain a polyethylene resin of white powder.

The produced polyethylene resin (PE125 resin) had a high density homopolyethylene fraction of 49 wt% and a low density polyethylene fraction of 51 wt%, a melt index flow at 190 DEG C and 5 kg of 0.09 g / 10 min, a density of 0.955, The molecular weight distribution measured by GPC was 33.5.

(3) Pipe forming

The obtained ethylene-based polymer was extrusion-molded by using a single-screw extruder (L / D = 28) at an extrusion temperature of 190 to 220 ° C so as to have an outer diameter of 32 mm and a thickness of 2.9 mm.

&Lt; Example 2 >

(1) Preparation of metallocene catalyst

The metallocene catalyst was prepared in the same manner as in Example 1.

(2) Production of polyethylene films

The polyethylene was prepared in the same manner as in Example 1, except that the feed rate of ethylene and hydrogen was adjusted to 1: 0.009 in the high-density polyethylene polymerization step and the polymerization time was adjusted to 70 minutes in the low-density polyethylene polymerization step.

(3) Pipe forming

The same procedure as in Example 1 was carried out to prepare a pipe-shaped body.

&Lt; Example 3 >

(1) Preparation of metallocene catalyst

The metallocene catalyst was prepared in the same manner as in Example 1.

(2) Production of polyethylene films

The polyethylene was produced in the same manner as in Example 1, except that the feed ratio of ethylene and hydrogen was adjusted to 1: 0.003 in the high-density polyethylene polymerization step.

(3) Pipe forming

The same procedure as in Example 1 was carried out to prepare a pipe-shaped body.

<Example 4>

(1) Preparation of metallocene catalyst

The metallocene catalyst was prepared in the same manner as in Example 1.

(2) Production of polyethylene films

The polyethylene was produced in the same manner as in Example 1, except that the charging ratio of ethylene and 1-octene was adjusted to 1: 0.00020 in the low-density polyethylene polymerization step.

(3) Pipe forming

The same procedure as in Example 1 was carried out to prepare a pipe-shaped body.

< Example  5>

(One) Metallocene  Preparation of Catalyst

The metallocene catalyst was prepared in the same manner as in Example 1.

(2) Production of polyethylene films

The polyethylene was prepared in the same manner as in Example 1, except that the polymerization time was adjusted to 75 minutes in the low-density polyethylene polymerization step.

(3) Pipe forming

The same procedure as in Example 1 was carried out to prepare a pipe-shaped body.

< Example  6>

(One) Metallocene  Preparation of Catalyst

The metallocene catalyst was prepared in the same manner as in Example 1.

(2) Production of polyethylene films

The polyethylene was produced in the same manner as in Example 1 except that 1-hexene was used as a comonomer in the low-density polyethylene polymerization step.

(3) Pipe forming

The same procedure as in Example 1 was carried out to prepare a pipe-shaped body.

< Example  7>

(One) Metallocene  Preparation of Catalyst

A metallocene catalyst was prepared in the same manner as in Example 1 except that rac-ethylene bis (1-tetrahydro-indenyl) zirconium dichloride was used as the metallocene compound.

(2) Production of polyethylene films

The polyethylene was produced in the same manner as in Example 1.

(3) Pipe forming

The same procedure as in Example 1 was carried out to prepare a pipe-shaped body.

< Comparative Example  1>

Except that Ziegler-Natta catalyst was used as a catalyst for polymerization and the feed ratio of ethylene and hydrogen was controlled at the high density polyethylene production stage and 1-butene was used at the low density polyethylene production stage and the feed rate of ethylene and 1-butene was controlled The polyethylene was produced in the same manner as in Example 1 to prepare a pipe-shaped body.

< Comparative Example  2>

The polyethylene was produced in the same manner as in Example 1, except that the feed ratio of ethylene and hydrogen was adjusted to 1: 0.0015 in the high-density polyethylene production step to prepare a pipe-shaped body.

< Comparative Example  3>

A commercially available polyethylene (PE100) for pipes was used to produce a pipe-shaped body.

< Experimental Example >

Pipe properties

1) Creep resistance

The molded pipe was subjected to a test stress in a thermostatic chamber at 20 ° C under the conditions of a pressure of 14.5 MPa and a pressure of 13.7 MPa, and the time until fracture was evaluated.

2) Pipe appearance

It was judged as good, normal, and bad by visual observation.

Polymerization conditions and analysis results (Examples 1 to 5) Item Example 1 Example 2 Example 3 Example 4 Example 5 High density
Homo-polyethylene Ethylene: Hydrogen input cost 1: 0.006 1: 0.009 1: 0.003 1: 0.006 1: 0.006 Fraction (wt%) 49 41 45 50 35 2.16 kg MI (g / 10 min) 2400 4300 400 2700 2400 Low density
Polyethylene Ethylene: comonomer charge 1: 0.00015 1: 0.00015 1: 0.00015 1: 0.00020 1: 0.00015 Fraction (wt%) 51 59 55 50 65 21.6 kg MI (g / 10 min) 0.15 0.14 0.15 0.15 0.15 Density (kg / m ³ ) 0.924 0.924 0.924 0.924 0.923 Polyethylene
Suzy 5 kg MI (g / 10 min) 0.09 0.12 0.07 0.26 0.06 Density (kg / m ³ ) 0.955 0.957 0.955 0.949 0.955 Mw / Mn 32.4 32.7 34.2 22.5 22.5

Polymerization conditions and analysis results (Examples 6 to 7 and Comparative Examples 1 and 2) Item Example 6 Example 7 Comparative Example 1 Comparative Example 2 High density
Homo-polyethylene Ethylene: Hydrogen input cost 1: 0.006 1: 0.006 1: 0.6 1: 0.0015 Fraction (wt%) 49 45 58 68 2.16 kg MI (g / 10 min) 2400 4400 2380 5 Low density
Polyethylene Ethylene: comonomer charge 1: 0.00015 1: 0.00015 1: 0.00018 1: 0.00015 Fraction (wt%) 51 55 42 32 21.6 kg MI (g / 10 min) 0.15 0.2 0.16 0.15 Density (kg / m ³ ) 0.925 0.922 0.925 0.924 Polyethylene
Suzy 5 kg MI (g / 10 min) 0.17 0.23 0.21 0.27 Density (kg / m ³ ) 0.956 0.954 0.947 0.952 Mw / Mn 24.2 29.4 30.9 19.7

Creep evaluation results (Examples 1 to 5) Item Example 1 Example 2 Example 3 Example 4 Example 5 14.5 MPa @ 20 C 722 591 508 328 464 13.7 MPa @ 20 C > 1500 > 1500 > 1500 1166 > 1500 Exterior Good Good Good Good Good

Creep evaluation results (Examples 6 to 7 and Comparative Examples 1 to 2) Item Example 6 Example 7 Comparative Example 1 Comparative Example 2 Comparative Example 3 14.5 MPa @ 20 C 1290 452 0 0 0 13.7 MPa @ 20 C > 1500 > 1500 0 72 0 Exterior Good Good Bad usually Good

As a result, it was confirmed that the polyethylene resins of Examples 1 to 7 had pressure resistance characteristics that were not broken within 100 hours at 20 占 폚, 14.5 MPa, and 1000 hours at 20 占 폚 and 13.7 MPa.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

Claims (15)

A step (step 1) of slurrying a solid polymethyl aluminoxane composition particle, a metallocene compound, an antistatic agent and a hydrocarbon solvent having a carbon atom number of 4 to 14,
here
The metallocene compound is added so that the molar ratio of the transition metal in the metallocene to the aluminum in the solid polymethylaluminoxane composition particles is 150: 1 to 600: 1,
Wherein the antistatic agent is added in an amount of 10 parts by weight to 50 parts by weight based on 100 parts by weight of the solid polymethylaluminoxane composition particles;
(Step 2) of polymerizing the slurry, the organoaluminum compound, the hydrocarbon solvent having carbon atoms of 4 to 14 carbon atoms, the ethylene monomer and hydrogen produced in step 1, and stirring the high-density homopolyethylene,
here
The organoaluminum compound is contained in an amount of 300 to 2000 parts by weight based on 100 parts by weight of the slurry,
The charging ratio of the ethylene monomer to hydrogen is 1: 0.003 to 0.009 (L / min: L / min)
The polymerization of step 2 is carried out at 60 to 90 DEG C, 3 to 15 bar for 1 to 4 hours,
Characterized in that the high density homopolyethylene has a melt index flow at 190 DEG C and 2.16 kg of from 400 to 5000 g / 10 min;
(Step 3) of polymerizing the low density polyethylene by mixing and stirring the ethylene monomer and the comonomer with the high density homopolyethylene produced in the step 2,
here
The polymerization of step 3 is carried out at 50 to 90 DEG C, 1 to 15 bar for 1 to 4 hours,
Characterized in that the low-density polyethylene has a melt flow rate of 0.01 to 0.30 g / 10 min at 190 占 폚 and 21.6 kg and a density of 0.912 to 0.930; And
And filtering and drying the resultant polyethylene (step 4). &Lt; IMAGE &gt;
The method according to claim 1,
Wherein the solid polymethylaluminoxane composition particles are obtained by mixing a solution of a polymethylaluminoxane composition containing polymethylaluminoxane and trimethylaluminum with an aromatic hydrocarbon solvent and heating the resulting polyaluminum aluminoxane composition particle, .
3. The method of claim 2,
Wherein the aromatic hydrocarbon solvent is at least one compound selected from the group consisting of benzene, toluene, ethylbenzene, propylbenzene, butylbenzene, xylene, chlorobenzene and dichlorobenzene. Way.
The method according to claim 1,
Wherein said step (1) is carried out by stirring said solid polymethylaluminoxane composition particles with said antistatic agent, and then adding metallocene.
The method according to claim 1,
Wherein the antistatic agent is at least one compound selected from the group consisting of glyceryl stearate, glyceryl monostearate, alkylamine, ethoxylated alkylamine, alkyl sulfonate, and glyceryl ester. Wherein the polyethylene resin for an excellent pipe is produced.
The method according to claim 1,
The hydrocarbon solvent having carbon atoms of 4 to 14 carbon atoms is at least one compound selected from the group consisting of pentane, hexane, cyclohexane, methylcyclohexane, heptane, octane, decane and isopentane. Gt;
The method according to claim 1,
The metallocene compound is selected from the group consisting of bis (cyclopentadienyl) zirconium dichloride, bis (cyclopentadienyl) zirconium methyl chloride, bis (cyclopentadienyl) zirconium dimethyl, bis (Methylcyclopentadienyl) zirconium dichloride, bis (ethylcyclopentadienyl) zirconium dichloride, bis (ethylcyclopentadienyl) zirconium dichloride, bis ) Zirconium dichloride, bis (pentamethylcyclopentadienyl) zirconium methyl chloride, bis (pentamethylcyclopentadienyl) zirconium dichloride, bis (pentamethylcyclopentadienyl) zirconium dichloride, Dimethyl, bis (n-butyl-cyclopentadienyl) zirconium dichloride, bis (n-butyl- (Indenyl) zirconium dichloride, bis (indenyl) zirconium methyl chloride, bis (indenyl) zirconium dimethyl, bis (n-butylcyclopentadienyl) zirconium dimethyl, bis (indenyl) zirconium dichloride, bis (2-methyl-indenyl) zirconium dichloride, bis (2-methyl-indenyl) zirconium dichloride, bis (Cyclopentadienyl) zirconium dichloride, dimethylsilylbis (cyclopentadienyl) zirconium methylchloride, bis (2-phenyl-indenyl) zirconium dichloride, bis , Dimethylsilylbis (cyclopentadienyl) zirconium dimethyl, dimethylsilylbis (indenyl) zirconium dichloride, dimethylsilyl (indenyl) zirconium methyl chloride, dimethylsilyl Indenyl) zirconium dichloride, dimethylsilylbis (2-methyl-indenyl) zirconium dichloride, dimethylsilylbis (2-methyl- (Indenyl cyclopentadienyl) zirconium dichloride, dimethylsilyl (indenyl cyclopentadienyl) zirconium methyl chloride, dimethylsilyl (indenyl cyclopentadienyl) zirconium dimethyl, dimethylsilyl (Cyclopentadienyl) zirconium dichloride, dimethylsilyl (fluorenylcyclopentadienyl) zirconium methylchloride, dimethylsilyl (fluorenylcyclopentadienyl) zirconium dimethyl, ethylene bis (cyclopentadienyl) zirconium dichloride , Ethylene bis (cyclopentadienyl) zirconium methyl chloride, ethylene bis (cyclopentadienyl) zirconium dimethyl, ethylene bis Zirconium dichloride, ethylene bis (indenyl) zirconium dichloride, ethylene bis (indenyl) zirconium dimethyl, ethylene bis (2-methyl- indenyl) zirconium dichloride, ethylene bis (Indenyl cyclopentadienyl) zirconium dichloride, ethylene (indenyl cyclopentadienyl) zirconium methyl chloride, enylene (including indenyl cyclopentadienyl) zirconium dichloride, Zirconium dichloride, ethylene (fluorenylcyclopentadienyl) zirconium dichloride, ethylene (fluorenylcyclopentadienyl) zirconium dimethyl, ethylene (fluorenylcyclopentadienyl) zirconium dichloride, ethylene (Cyclopentadienyl) zirconium dichloride, isopropylbis (cyclopentadienyl) zirconium methyl chloride, isopropyl (Indenyl) zirconium dichloride, isopropylbis (indenyl) zirconium methyl chloride, isopropylbis (indenyl) zirconium dimethyl, isopropyl bis (indenyl) zirconium dichloride, Indenyl) zirconium dichloride, isopropyl (2-methyl-indenyl) zirconium methyl chloride, isopropyl (2-methyl- indenyl) zirconium dimethyl, isopropyl (indenyl cyclopentadienyl) zirconium dichloride, (Propenylcyclopentadienyl) zirconium dichloride, isopropyl (indenyl cyclopentadienyl) zirconium methyl chloride, isopropyl (indenyl cyclopentadienyl) zirconium dimethyl, isopropyl (fluorenylcyclopentadienyl) zirconium dichloride, isopropyl Dienyl) zirconium methyl chloride and isopropyl (fluorenylcyclopentadienyl) zirconium dimethyl, rac-ethylene bis (1-indenyl) zirconium (1-tetrahydroindenyl) zirconium dichloride, rac-ethylene bis (1-indenyl) hafnium dichloride, rac-ethylene bis (1-tetrahydroindenyl) zirconium dichloride, rac- (2-methyl-tetrahydrobenzenylidene) zirconium dichloride, rac-dimethylsilanediylbis (2-methyl-tetrahydrobenzenylenyl) hafnium dichloride, rac-diphenyl Diphenylsilandiylbis (2-methyl-tetrahydrobenzenylenyl) hafnium dichloride, rac-dimethylsilanediylbis (2-methyl-tetrahydrobenzenylidene) zirconium dichloride, rac- (2-methyl-4,5-benzindenyl) hafnium dichloride, rac-diphenylsilanediylbis (2-methyl-4,5-benzindenyl) zirconium dichloride, -Methyl-4,5-benzindenyl) zirconium dichloride, rac-diphenylsilane (2-methyl-5,6-cyclopentadienylindenyl) zirconium dichloride, rac-dimethylsilylbis (2-methyl-4,5-benzindenyl) hafnium dichloride, rac- (2-methyl-5,6-cyclopentadienylindenyl) hafnium dichloride, rac-diphenylsilandiylbis (2-methyl-5,6-cyclopentadienylindenyl) zirconium dichloride (2-methyl-5,6-cyclopentadienylindenyl) hafnium dichloride, rac-dimethylsilylbis (2-methyl-4-phenylindenyl) zirconium dichloride, rac-diphenylsilanediylbis Diphenylsilylbis (2-methyl-4-phenylindenyl) zirconium dichloride, rac-diphenylsilylbis (2-methyl-4-phenylindenyl) hafnium dichloride, rac- -4-phenylindenyl) hafnium dichloride, characterized in that it is at least one compound selected from the group consisting of Process for producing a polyethylene resin.
The method according to claim 1,
The organoaluminum compound of step 2 is _{Al (C 2 H 5) 3} , Al (C 2 H 5) 2 H, Al (C 3 H 7) 3, Al (C 3 H 7) 2 H, Al (iC 4 _{H 9) 2 H, Al (} C 8 H 17) 3, Al (C 12 H 25) 3, Al (C 2 H 5) (C 12 H 25) 2, Al (iC 4 H 9) (C 12 H ₂₅ ) ₂ , Al (iC ₄ H ₉ ) ₃ , (C ₂ H ₅ ) ₂ AlCl, (iC ₃ H ₉ ) ₂ AlCl and (C ₂ H ₅ ) ₃ Al ₂ Cl ₃ . Wherein the polypropylene resin is a polypropylene resin.
delete The method according to claim 1,
Wherein the comonomer of step 3 is at least one compound selected from the group consisting of butene, hexene, methylpentene, and octene.
delete The method according to claim 1,
The polyethylene resin produced through the step 4 had a high density homopolyethylene fraction of 35 to 65 wt% and a low density polyethylene fraction of 35 to 65 wt%, and a melt index flow at 190 DEG C and 5 kg of 0.01 to 1.0 g / 10 Min, a density of 0.940 to 0.960, and a molecular weight distribution as measured by GPC of 20 to 50. The method for producing a polyethylene resin for a pipe according to claim 1,
7. A process for preparing a compound according to claim 1,
The density fraction of the high density homopolyethylene is 35 to 65 wt%, the fraction of the low density polyethylene is 35 to 65 wt%, the melt index flow at 190 DEG C and 5 kg is 0.01 to 1.0 g / 10 min, the density is 0.940 to 0.960, Characterized in that the molecular weight distribution measured by the method has a value of 20 to 50,
Polyethylene resin for pipes excellent in pressure resistance characteristics.
delete A pipe formed article made of the polyethylene resin according to claim 13, characterized in that the withstand pressure characteristic of the pipe is not destroyed at 20 ° C, 14.5 MPa for 100 hours and at 20 ° C and 13.7 MPa within 1000 hours.