KR101503567B1 - Method of preparing polyolefin - Google Patents

Abstract

The present invention relates to a process for producing a polyolefin using a metallocene supported catalyst and two or more stages of multistage polymerization processes in which a catalyst is reacted with an ethylene monomer in the presence of a metallocene supported catalyst and an inert gas in a first reactor, The polyolefin produced by introducing the molecular weight regulator into the second reactor is increased by increasing the melt index of the polyolefin produced by reacting the slurry mixture and the ethylene monomer transferred in the first reactor in the presence of the molecular weight regulator in the second reactor, (PDI) of a polyolefin produced by lowering the melt index of a polyolefin resin having a high density-to-density crack resistance (FNCT) and an excellent workability, and is particularly suitable for blow molding molding .

Description

TECHNICAL FIELD The present invention relates to a method for preparing a polyolefin resin,

The present invention relates to a process for producing a polyolefin resin, and more particularly, to a process for producing a polyolefin resin, which comprises a metallocene supported catalyst and a polydispersity index (PDI) of a polyolefin prepared by using a multi- To a process for producing a polyolefin resin which is excellent in stress cracking property (Full Notch Creep Test: FNCT) and is excellent in processing and therefore particularly suitable for blow molding.

In general, products manufactured using blow molding require excellent workability and stress cracking resistance. Efforts have been made to reduce the amount of materials used to meet these requirements and to reduce costs, which should be supported by excellent physical properties and stress cracking resistance.

In general, metallocene catalysts using a Group 4 transition metal are easier to control molecular weight and molecular weight distribution than conventional Ziegler-Natta catalysts, and can control the distribution of comonomers in polymers, Have been used. Nonetheless, polymers produced using metallocene catalysts have problems of poor processability due to their narrow molecular weight distribution, and as a result, it has become an important development objective to simultaneously satisfy workability, density, and stress cracking resistance.

In the case of blow molding products, the polyethylene made from metallocene has a high viscosity at high shear rate, which results in a large amount of pressure or extrusion at the time of extrusion, resulting in poor extrusion productivity, unevenness of the surface of the molded product, and extrusion The stability of the outgoing parisons can also be reduced. Particularly, in the case of a small blow molding product in which the size of the blow molding product container is reduced from 0.5 liters to 20 liters or less, the property requirements such as the bending strength are increased, and accordingly, it becomes more difficult to match the processability to the improved physical properties.

Also, in order to improve the physical properties of the multistage polymerization process, the polyolefin having a high melt index is produced in the first reactor. When the metallocene supported catalyst is used, polymerization in the second reactor is not sufficient depending on the duration of polymerization in the reactor The average molecular weight of the material to be finally produced can not be improved and the melt index of the desired final polyolefin can not be adjusted accordingly.

Therefore, when a metallocene catalyst is applied to a multi-stage reactor, it is urgently required to develop a process for producing a polyolefin which maintains excellent catalytic activity and maintains excellent mechanical properties and greatly improves workability.

Korean Patent Publication No. 2002-0086940 (published on November 20, 2002)

In order to solve the problems of the prior art as described above, the present invention provides a process for producing a polyolefin using a metallocene supported catalyst and a multistage polymerization process of two or more stages, wherein the activity of the metallocene supported catalyst inserted in the first reactor is longer The PDI of the polyolefin produced by increasing the amount of the polyolefin produced in the second or higher reactor is high, the full notch creep test (FNCT) with respect to density is good, and the processing is easy, It is an object of the present invention to provide a method for producing a polyolefin particularly suitable for molding.

These and other objects of the present invention can be achieved by the present invention described below.

In order to achieve the above object, the present invention relates to a process for producing a polyolefin by using a metallocene supported catalyst and a two-stage or more multi-stage polymerization process, in the presence of a metallocene supported catalyst and an inert gas in a first reactor, After the catalyst is reacted and the gas is discharged from the flash vessel, the slurry mixture in the first reactor and the ethylene monomer are reacted in the second reactor in the presence of a chain propagation agent (CPA) to prepare an ethylene polymer having a broad molecular weight distribution The method comprising the steps of:

As described above, according to the present invention, the activity of the metallocene supported catalyst introduced in the first reactor is maintained longer, and the polydispersity of the polyolefin prepared by increasing the weight ratio of the polyolefin produced in the second reactor , A polyolefin having a high PDI and excellent density-to-stress cracking resistance and being easy to process, is particularly suitable for medium-sized blow molding.

1 is a schematic diagram showing a multi-stage polymerization process of polyethylene using a continuous CSTR reactor in accordance with an embodiment of the present invention.
2 is a graph showing the amount of ethylene charged and the cumulative amount of ethylene according to Example 4 and Comparative Example 3 of the present invention.

The present invention relates to a method for producing polyethylene by a multistage polymerization process using a metallocene supported catalyst, comprising the steps of: polymerizing polyethylene in a first reactor in the presence of a metallocene supported catalyst and an inert gas (nitrogen) And then a molecular weight regulator is added to the second reactor to finally produce a polyolefin having a broad molecular weight distribution.

The present invention is described in detail as follows.

The method for producing polyethylene resin according to the present invention is a method for producing polyethylene by reacting an ethylene monomer and a catalyst in a reactor in which a first reactor and a second reactor are connected in series, the method comprising the steps of: (i) Reacting an ethylene monomer with a catalyst in the presence of an inert gas to produce an ethylene polymer; (ii) transferring the slurry mixture to a flash vessel to discharge the gas; And (iii) reacting an ethylene monomer and a slurry mixture transferred in the first reactor in the presence of a molecular weight regulator in a second reactor to produce an ethylene polymer having a broad molecular weight distribution.

In the present invention, polyethylene is produced by reacting an ethylene monomer and a catalyst in a reactor in which a first reactor, a flash vessel and a second reactor are connected in series, and a post reactor may be further connected to the second reactor.

The polymerization process of the first reactor

The first reactor is produced by reacting an ethylene monomer with a catalyst in the presence of a metallocene supported catalyst and an inert gas. The inert gas is preferably nitrogen.

The nitrogen increases the duration of activity of the catalyst in the second reactor. That is, in the first reactor, the initial rapid reaction of the metallocene-supported catalyst is inhibited, and then the reaction of the catalyst in the second reactor is inhibited to increase the amount of polyethylene in the second reactor / the amount of polyethylene in the first reactor It plays a role.

In the production of the ethylene polymer, hydrogen is not used or may be further added in an amount of from 0 to 5% by weight of the total monomers. If it is outside the above range, the volatile components may be increased during processing of the final product.

The metallocene supported catalyst is preferably a mixed metallocene supported catalyst comprising a support, a first co-catalyst, a second co-catalyst, a first metallocene compound and a second metallocene compound.

As the carrier used for the metallocene supported catalyst, for example, silica dried at high temperature, silica-alumina, silica-magnesia and the like may be used. The carrier is dried at a high temperature. The drying temperature of the carrier is 180 to 800 ° C. When the temperature is lower than 180 ° C, the moisture is too much to react with the cocatalyst to deteriorate performance. When the temperature exceeds 800 ° C, The silane group is left only and the siloxane group is left, and the reaction site with the cocatalyst is reduced.

The first cocatalyst is an organometallic compound containing aluminum and can be represented by the following formula (1).

In Formula 1, R ¹ is the same or different from each other a halogen radical, hydrocarbyl radical of 1 to 20 carbon atoms substituted with a halogen or a hydrocarbyl radical having 1 to 20, n is an integer of 2 or more.

The compounds of formula (I) may exist in a linear, circular or network form, for example, methyl aluminoxane (MAO), ethyl aluminoxane, isobutyl aluminoxane or butyl aluminoxane.

The second co-catalyst may be a borate-based compound containing boron represented by the following formula (2).

Wherein T ⁺ is a polyatomic ion of +1 valence, B is boron of the +3 type oxidation state, and each Q is independently selected from the group consisting of hydride, dialkylamido, halide, alkoxide, aryloxide, hydrocarbyl, halo Carbyl and halo-substituted hydrocarbyl radicals, wherein Q has not more than 20 carbons, and when Q is a halide, said halide is one.

Non-limiting examples of the compound of Formula 2 above include trisubstituted ammonium salts such as trimetalammonium tetraphenylborate, methyl dioctadecylammonium tetraphenylborate, triethylammonium tetraphenylborate, tripropylammonium tetraphenylborate N, N-dimethylanilinium tetraphenylborate, N, N-diethylanilinium tetraphenylborate, N, N (trimethylammonium) tetraphenylborate, tri -Methyltetradecylammonium tetrakis (pentaphenyl) borate, methyl dioctadecylammonium tetrakis (pentafluorophenyl) borate, dimethyldodecyldimethylammonium tetrakis (pentafluorophenyl) borate, Pentafluorophenyl) borate, triethylammonium, tetrakis (pentafluorophenyl) borate, tripropylammonium tetrakis (pentafluoro (Pentafluorophenyl) borate, N, N-dimethylanilinium tetrakis (pentafluorophenyl) borate, tri (n-butyl) ammonium tetrakis (Pentafluorophenyl) borate, N, N-diethylanilinium tetrakis (pentafluorophenyl) borate, N, N-dimethyl (2,4,6-trimethylanilinium) tetrakis , Trimethylammonium tetrakis (2,3,4,6-tetrafluorophenyl) borate, triethylammonium tetrakis (2,3,4,6-tetrafluorophenyl) borate, tripropylammonium tetrakis (2, Tri (n-butyl) ammonium tetrakis (2,3,4,6-tetrafluorophenyl) borate, dimethyl (t-butyl) ammonium tetrakis , 3,4,6-tetrafluorophenyl) borate, N, N-dimethylanilinium tetrakis (2,3,4,6-tetrafluorophenyl) borate, N, Tetrakis (2,3,4,6-tetrafluorophenyl) borate and N, N-dimethyl- (2,4,6-trimethylanilinium) tetrakis- (2,3,4,6- (Pentafluorophenyl) borate, dicyclohexylammonium tetrakis (pentafluorophenyl) borate, dicetyldimethylammonium tetrakis (pentafluorophenyl) borate, ditetradecylammonium tetrakis Phenyl) borate; Tri-substituted phosphonium salts such as triphenylphosphonium tetrakis (pentafluorophenyl) borate, methyl dioctadecylphosphonium tetrakis (pentafluorophenyl) borate and tri (2,6-, dimethylphenyl) Phosphonium tetrakis (pentafluorophenyl) borate. (Octadecyl) ammonium tetrakis (pentafluorophenyl) borate and methyldi (tetradecyl) ammonium tetrakis (pentafluorophenyl) amide complexes, especially the C14-C20 alkyl ammonium complexes, ) Borate or a mixture comprising them is preferred.

The first metallocene compound may be a compound represented by Formula 3, and the second metallocene compound may be a compound represented by Formula 4 below.

In the formula (3) or (4)

R ^m, R ⁿ are each the same or different hydrogen radical, alkyl, cycloalkyl, aryl, alkenyl having 1 to 20 carbon atoms, alkylaryl, arylalkyl, arylalkenyl a radical or alkylsilyl radical, R ¹ and R ² is And a, a ', b, or b' each represent an integer of 1 to 4,

M is a transition metal of Group 4B, 5B or 6B of the periodic table,

Q is a halogen radical or an alkyl radical alkenyl radical having 1 to 20 carbon atoms, an aryl radical alkylaryl radical, an arylalkyl radical or an alkylidene radical having 1 to 20 carbon atoms,

B is any one selected from the group consisting of an alkyl radical having 1 to 4 carbon atoms or a hydrocarbyl radical containing silicon, germanium, phosphorus, nitrogen, boron or aluminum,

J is any one selected from the group consisting of NR ⁵ , O, PR ^5, and S, and R ⁵ is an alkyl radical or a substituted alkyl radical having 1 to 20 carbon atoms,

Preferably, any hydrogen radical present in said R ^m , R ⁿ , B or R ⁵ is alkoxy, aryloxy, alkylthio, arylthio, amino, phenyl or substituted phenyl having 1 to 20 carbon atoms, Alkoxy of 1 to 20 carbon atoms,

Representative examples of such functional groups are from the group consisting of methoxymethyl, t-butoxymethyl, tetrahydropyranyl, tetrahydrofuranyl, 1-ethoxyethyl, 1-methyl-1-methoxyethyl and t- And can be any one selected.

A representative example of the metallocene compound represented by the formula (3) of the present invention is [AO- (CH ₂ ) _a -C ₅ H ₄ ] ₂ ZrCl ₂ wherein a is an integer of 4 to 8 and A Is any one selected from the group consisting of methoxymethyl, t-butoxymethyl, tetrahydropyranyl, tetrahydrofuranyl, 1-ethoxyethyl, 1-methyl-1-methoxyethyl and t- have.

A representative example of the metallocene compound represented by Formula 4 of the present invention is [(A'-D- (CH ₂ ) _a ] (CH ₃ ) X (C ₅ Me ₄ ) (NCMe ₃ )] TiCl ₂ , X is methylene, ethylene or silicon, D is oxygen or nitrogen atom, A 'is hydrogen, alkyl having 1 to 20 carbon atoms, aryl, alkylaryl, arylalkyl, alkylsilyl, arylsilyl, methoxymethyl , t-butoxymethyl, tetrahydropyranyl, tetrahydrofuranyl, 1-ethoxyethyl, 1-methyl-1-methoxyethyl and t-alkylsilyl, arylsilyl, methoxymethyl, , Tetrahydropyranyl, tetrahydrofuranyl, 1-ethoxyethyl, 1-methyl-1-methoxyethyl and t-butyl.

The most preferred preparation procedure for preparing the hybrid metallocene supported catalyst comprises the steps of reacting a first metallocene compound with a carrier to prepare a carrier carrying the first metallocene compound, A step of reacting a supported catalyst with a first co-catalyst to prepare a carrier on which the first metallocene compound and the first co-catalyst are supported; Reacting the metallocene compound; And a metallocene catalyst carrying a first metallocene compound, a first co-catalyst and a second metallocene compound are reacted with a second co-catalyst to finally obtain a first metallocene compound, a second metallocene compound, And a step of preparing a metallocene catalyst carrying the first catalyst and the second catalyst.

This process is performed stepwise and it is preferable to carry out a washing process using a solvent between each step.

The first reactor and the second reactor may be continuously fed with the organoaluminum compound as a material for removing moisture in the reactor. The organoaluminum compound is preferably selected from the group consisting of trialkylaluminum, dialkylaluminum halide, alkylaluminum dihalide, aluminum dialkylhydride and alkylaluminum sesquihalide. More preferably _{Al (C 2 H 5) 3} , Al (C 2 H 5) 2 H, Al (C 3 H 7) 3, Al (C 3 H 7) 2 H, Al (iC 4 H 9) 2 _{H, Al (C 8 H 17} ) 3, Al (C 12 H 25) 3, Al (C 2 H 5) (C 12 H 25) 2, Al (iC 4 H 9) (C 12 H 25) 2, _{Al (iC 4 H 9) 2} H, Al (iC 4 H 9) 3, (C 2 H 5) 2 AlCl, (iC 3 H 9) 2 AlCl , or (C ₂ H ₅₎ using a ₃ Al ₂ Cl ₃ do. The amount of the organoaluminum compound to be added can be selected without particular limitation as long as it can remove moisture, but it is preferably 0.1 to 10 moles per kg of hexane.

The retention time of the raw material in the polymerization step of the first reactor may be selected within a range capable of forming an ethylene polymer having an appropriate molecular weight distribution and density distribution without particular limitation, but is preferably in the range of 1 hour to 3 hours. If the time is shorter than the above range, the processability of the final polyethylene product may be lowered. If it is larger than the above range, the process cycle is longer than the production amount, which is not efficient from the viewpoint of productivity.

The inert gas such as nitrogen and the ethylene mass ratio may be selected depending on the molecular weight of the desired end product as well as the inherent characteristics of the catalyst, but it is preferably 1:10 to 1: 100. When the amount of the inert gas is less than the above range, the catalytic activity is not sufficiently realized in the second reactor, so that the desired molecular weight distribution can not be obtained. When the inert gas is supplied in an amount larger than the above range, May not be fully realized.

The polymerization reaction temperature in the first reactor is not particularly limited as long as it can form an appropriate molecular weight distribution and density distribution, but it is preferably 70 to 90 ° C. If the temperature is lower than the above range, the polymerization reaction rate is reduced and the cost of product production is increased. If the temperature is higher than the above range, fouling in the reactor may be caused.

The polymerization pressure in the first reactor can be selected without particular limitation as long as it can form an appropriate molecular weight distribution and a density distribution, but it is preferably 8 to 10 bar to maintain a stable continuous process state.

The reaction mixture may further comprise a diluent component, and most of the diluent is hexane and may contain minor amounts of other alkanes or alkenes such as butane, pentane. Such a diluent may be introduced in the form of gas phase or liquid phase, or both, and the liquid phase diluent may be added into the bottom of the reactor or directly into the polymer phase. The amount of the diluent is preferably in the range of 1.1 to 5.1 in the diluent and in the ethylene. If the diluent is lower than 1.1, there is a problem in the heat. If the diluent is higher than 5.1, the production efficiency is lower than the reactor size.

The ethylene polymer formed in the first reactor preferably has a weight average molecular weight of 10,000 to 100,000, a polydispersity of 1.5 to 5.0, and a low molecular weight of 1000 to 10 at a melt index of 5 kg and 190 ° C. In addition, the production ratio of the polymer produced in the first reactor among the final products is preferably 40 to 70% by weight. The polymerization reaction in the first reactor can be either gas phase polymerization or liquid phase polymerization, and liquid phase polymerization with a slurry phase is preferable in view of reaction efficiency.

Flash Bessel ( flash vessel )

The slurry mixture, which is located between the first and second reactors, is discharged to the outside while stirring the slurry mixture transferred in the first reactor to reduce the ratio of hydrogen and nitrogen.

During the polymerization process for the preparation of the solid polymer, a polymer effluent, usually comprising a slurry of the polymer solids in a liquid medium comprising the reactive diluent and the unreacted monomers, is formed, and the polymer effluent is recovered from the effluent It is necessary to separate the polymer solids from the residue. In order to recover the diluent, monomer or comonomer from the reaction effluent, a flash process is generally used as soon as the diluent is removed from the effluent. In the polymerization process of the present invention, this principle of the instantaneous evaporation process is applied, and the most volatile hydrogen and nitrogen are selectively removed by using a flash vessel between the first reactor and the second reactor.

The pressure is controlled by controlling the pressure of the first reactor to 9 bar or less and the pressure of the second reactor to 7 bar or more. The temperature is the same as the operating range of the first reactor. That is, it is preferably 70 to 90 ° C. Also, the residence time is preferably from 5 minutes to 30 minutes, which is a time required for discharging the gas.

The polymerization process of the second reactor

In the second reactor connected in series with the first reactor, the ethylene monomer and the comonomer are further charged and reacted in the presence of the molecular weight regulator without addition of additional catalyst to prepare a high molecular weight ethylene polymer.

The molecular weight modifier is preferably an organometallic complex, more preferably an organometallic complex, most preferably a cyclopentadienyl metal compound represented by the following formula (5) and an organoaluminum compound represented by the following formula In this case, the effect of lowering the polymer melt index, increasing the molecular weight polydispersity, and improving the stress cracking resistance compared to the density or the polymer melt index is significant.

In the formula (5), Cp ¹ and Cp ² independently represent a cyclopentadienyl, an indenyl, a fluorenyl group or a derivative thereof as a ligand, M is titanium, zirconium or hafnium, and X is a halogen element.

Specific examples of the cyclopentadienyl metal compound include biscyclopentadienyl titanium dichloride, biscyclopentadienyl zirconium dichloride, biscyclopentadienyl hafnium dichloride, bisindenyl titanium dichloride, and bis-fluorenyl titanium di Chloride, and the like.

In Formula 6, R ¹ , R ^2, or R ³ may independently be a C 1 to C 20 alkyl substituent or a halogen, and may include a hetero element such as nitrogen or oxygen.

The organoaluminum compound is selected from the group consisting of trimethylaluminum, triethylaluminum, tripropylaluminum, triisopropylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, dimethylaluminum chloride, diethylaluminum chloride, dipropylaluminum chloride, It is preferably at least one member selected from the group consisting of butyl aluminum chloride, dihexyl aluminum chloride, dimethyl aluminum dichloride, ethyl aluminum dichloride, propyl aluminum dichloride, isobutyl aluminum dichloride and ethyl aluminum sesqui floride.

The molar ratio (M: Al) of the cyclopentadienyl metal compound (M) to the organoaluminum compound (Al) is preferably 1.0: 1 to 1: 100.

It is preferable that the content of M in the organometallic complex compound is 0.001 μmol / 1 kg to 10 μmol / 1 kg based on 1 kg of total ethylene fed into the entire reactor. When the molecular weight regulator is added in a range lower than this range, the molecular weight and polydispersity of the final product can not be sufficiently increased. When the amount of the molecular weight regulator is more than this range, the activity of the catalyst becomes too low.

The comonomer is not used in the production of the polyethylene, or it is preferably added to the second reactor during the production of the high molecular weight ethylene polymer. As the comonomer usable in the second reactor, a C2-C10 alpha-olefin can be used, and 1-butene or 1-hexene is preferably used. The comonomer may further be added in an amount of 0 to 20% by weight of the total monomers.

When the comonomer is used in a large amount, a large amount of tie-molecule is formed on the high molecular weight side to improve the impact strength and environmental stress crack resistance (ESCR), while the density of the polymer is lowered, Weakened.

The retention time of the raw material in the polymerization step of the second reactor may be selected within a range capable of forming an ethylene polymer having an appropriate molecular weight distribution and a density distribution without particular limitation, but is preferably in the range of 1 to 3 hours. If the time is shorter than the above range, the environmental stress cracking resistance of the final polyethylene product may be lowered. If it is larger than the above range, the production amount in the second reactor is not increased and the process efficiency for producing the product is lowered.

The polymerization reaction temperature in the second reactor may be selected within a range capable of forming an appropriate molecular weight distribution and a density distribution without particular limitation, and is preferably 60 to 90 ° C. If the temperature is lower than the above range, the polymerization reaction rate is reduced and the cost of product production is increased. If the temperature is higher than the above range, fouling in the reactor may be caused.

The polymerization reaction pressure in the second reactor can be selected without particular limitation as long as it can form an appropriate molecular weight distribution and density distribution, but it is preferably 6 to 9 bar to maintain a stable continuous process state.

The reaction mixture may further comprise a diluent component, and most of the diluent is hexane and may contain minor amounts of other alkanes or alkenes such as butane, pentane. Such a diluent may be introduced in the form of gas phase or liquid phase, or both, and the liquid phase diluent may be added into the bottom of the reactor or directly into the polymer phase. The amount of the diluent is preferably in the range of 1: 1 to 5: 1 by weight of the diluent and ethylene. When the diluent is lower than 1: 1, there is a problem in the heat. When the diluent is higher than 5: 1,

The ethylene polymer formed in the second reactor preferably has a weight average molecular weight of 150,000 to 300,000, a polydispersity of 5 to 20, a melt index of 5 kg and a polymer content of 10 to 0.1 at 190 ° C. In addition, the production ratio of the polymer produced in the second reactor among the final products is preferably 30 to 60% by weight. The polymerization reaction in the second reactor can be either gas phase polymerization or liquid phase polymerization, and liquid phase polymerization with a slurry phase is preferable in terms of efficiency of reaction.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims.

[Example]

Manufacturing example  1: [t- This -O ( CH ₂ ) ₆ - C ₅ H ₄ ] ₂ ZrCl ₂ Synthesis of

Using 6-chlorohexanol, the title compound was obtained from Tetrahedron < RTI ID = 0.0 > Lett . 2951 product as the (1988)) t-butyl- O- (CH 2) ₆ -Cl and manufactures, by reacting NaC ₅ H ₅ herein _{t-butyl-O- (CH 2} ) 6 -C 5 H ₅ (yield 60%, bp 80 ° C / 0.1 mmHg).

2.0 g (9.0 mmol) of t-butyl-O- (CH ₂ ) ₆ -C ₅ H ₅ was dissolved in THF at -78 ° C. 1.0 eq of n-BuLi was slowly added thereto, , And reacted for 8 hours. The reaction solution was slowly added to a suspension of ZrCl ₄ (THF) ₂ (1.70 g, 4.50 mmol) / THF (30 ml) at -78 ° C. and then reacted at room temperature for 6 hours to produce a final reaction Solution.

The reaction product liquid was vacuum dried to remove all volatile substances, and hexane was added to the remaining oily liquid substance, followed by filtration using a schlenk glass filter. The filtered solution was vacuum-dried to remove hexane, and hexane was further added thereto to induce precipitation at a low temperature (-20 ° C). The obtained precipitate was filtered off at a low temperature to obtain [t-Bu-O (CH ₂ ) ₆ -C ₅ H ₄ ] ₂ ZrCl ₂ compound in a yield of 92% as a white solid. The measured ¹ H NMR and ¹³ C NMR data of [t-Bu-O (CH ₂ ) ₆ -C ₅ H ₄ ] ₂ ZrCl _{2 obtained} were as follows.

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

_{13C NMR (CDCl 3): 135.09} , 116.66, 112.28, 72.42, 61.52, 30.66, 30.61, 30.14, 29.18, 27.58, 26.00

Manufacturing example  2: [ methyl (6-t- butoxyhexyl ) silyl (? ⁵ -tetramethylcyclopentadienyl) (t- butylamido ) TiCl ₂ Synthesis of

50 g of Mg (solid) was added to a 10 L reactor at room temperature, and then 300 ml of THF was added. After 0.5 g of I ₂ was added thereto, the reactor temperature was maintained at 50 ° C.

After the temperature of the reactor was stabilized, 250 g of 6-t-buthoxyhexyl chloride was added to the reactor at a rate of 5 ml / min using a feeding pump and stirred for 12 hours 6-t-buthoxyhexyl magnesium chloride (6-t-buthoxyhexyl magnesium chloride) was prepared by adding 6-t-butoxyhexyl chloride and raising the temperature of the reactor by about 4-5 ° C.

The 6-t-butoxyhexylmagnesium chloride was obtained as a black reaction solution. 2 ml of the black reaction solution was added, and water was added to obtain an organic layer. The compound contained in the organic layer was analyzed by ¹ H-NMR The result of the reaction was confirmed to be 6-t-buthoxyhexane.

500 g of MeSiCl ₃ and 1 L of THF were added to a separate reactor and the reactor temperature was cooled to -20 ° C. To the reactor, 560 g of 6-t-butoxyhexylmagnesium chloride prepared in the future was introduced at a rate of 5 mL / min using an injection pump, and then the reactor temperature was slowly elevated to room temperature and stirred for 12 hours.

After stirring for 12 hours, it was confirmed that white MgCl ₂ salt was formed. 4 L of hexane was added thereto, and the filtered solution was obtained by removing the salt through a laboratory pressure dehydration filter (labdori, Han Kang Engineering Co., Ltd.).

The filtered solution was added to the reactor, and the hexane was removed at 70 ° C to obtain a pale yellow liquid, which was confirmed to be methyl (6-t-butoxyhexyl) dichlorosilane compound by ¹ H NMR.

_{^{1 H NMR (CDCl 3):}} 3.3 (t, 2H), 1.5 (m, 3H), 1.3 (m, 5H), 1.2 (s, 9H), 1.1 (m, 2H), 0.7 (s, 3H)

After 1.2 moles (150 g) of tetramethylcyclopentadiene and 2.4 L of THF were added to the separate reactor, the reactor was cooled to -20 캜, and then 480 mL of 2.5M concentration n-BuLi was injected at a rate of 5 mL / min Respectively. After the addition of n-BuLi, the reactor temperature was slowly elevated to room temperature and stirred for 12 hours. Then, 326 g (350 ml) of methyl (6-t-butoxyhexyl) dichlorosilane Lt; / RTI > The reactor temperature was slowly added to that raising to room temperature and then stirred for 12 hours, cooling the reactor temperature to 0 ℃ and then 2 equivalents of t-BuNH _2.

The reactor temperature was slowly raised to room temperature and stirred for 12 hours. Then, THF was removed and 4 L of hexane was added. Then, the salt was removed through a laboratory pressurized dehydration filter (labdori, Han River Engineering) there was. The filtered solution was added to the reactor again, and hexane was removed at 70 ° C to obtain a yellow solution, which was analyzed by 1H NMR for methyl (6-t-butoxyhexyl) tetramethylcyclopentadienyl) t-butylamino Silane (6-t-buthoxyhexyl) (tetramethylcyclopentadienyl) t-butylaminosilane).

(6-t-buthoxyhexyl) t-butylamino silane) was reacted with n-BuLi in THF at -78 ° C. 10 mmol of TiCl ₃ (THF) ₃ was rapidly added to the resulting dilithium salt solution, followed by stirring for 12 hours while slowly raising the temperature to -78 ° C. After stirring for 12 hours, 10 mmol of an equivalent amount of PbCl ₂ was added to the reaction solution at room temperature and stirred for 12 hours to obtain a dark black solution.

After removal of THF from the dark black solution, hexane was added and filtered to obtain a filtered solution. The hexane was removed from the filter solution, and the remaining material was purified by ¹ H NMR to give methyl (6-t-butoxyhexyl) silyl (eta ⁵ -tetramethylcyclopentadienyl) (t- butylamido) TiCl ₂ (it was identified as methyl (6-t-buthoxyhexyl) silyl (η 5 -tetramethylCp) (t-butylamido) TiCl 2.

_{1H NMR (CDCl 3): 3.3} (s, 4H), 2.2 (s, 6H), 2.1 (s, 6H), 1.8 - 0.8 (m), 1.4 (s, 9H), 1.2 <136> (s, 9H ), 0.7 (s, 3H)

Manufacturing example  3: Metallocene  Preparation of Supported Catalyst

30 ml of toluene was added to 3 g of calcined silica (Sylopol 2212, Grace Davison) having a surface area of 280 m ² / g and a pore volume of 1.47 ml / g, and then 30 ml of [t-Bu-O - (CH ₂ ) ₆ --C ₅ H ₄ ] ₂ ZrCl ₂ was added and reacted for 1 hour. The remaining solid component was washed with toluene. The solid component was reacted with 15 ml of methylaluminoxane (MAO) (70 wt% toluene solution) at 70 캜 for 2 hours and then washed with toluene to remove unreacted MAO solution to prepare a solid component containing methylaluminoxane.

(6-t-butoxyhexyl) silyl (η ⁵ -tetramethylcyclopentadienyl) (t-butylamido) TiCl ₂ prepared in Preparation Example 2 and the total amount of the solid component containing methylaluminoxane 0.36 mmole of methyl (6-t-buthoxyhexyl) silyl (η ⁵ -tetramethylcyclopentadienyl) (t-butylamido) TiCl ₂ was washed and the washed solid component was mixed with trityl tetrakis (penta-fluoro-phenyl) 1.2 mmol of tetrakis (penta-fluoro-phenyl) borate (TB) was dried under reduced pressure at 50 ° C using toluene as a solvent to prepare a solid metallocene supported catalyst. Boron (B) / transition metal ) Was 1.3.

Manufacturing example  4: Preparation of molecular weight regulator

1.25 g of bis (cyclopentadienyl) titanium dichloride and 10 ml of toluene were sequentially added to a 250 ml round bottom flask and stirred. To this was added 10 ml of triisooctylalumium (1M in hexane), stirred at room temperature for 3 days, and then the solvent was removed in vacuo to obtain a green mixture, which was oxidized or colored It did not change. Hereinafter, the green mixture was used without purification. Also, it was confirmed by 1 H NMR that the mixture was bis (cyclopentadienyl) octyl titanium and dioctylaluminium chloride.

¹ H NMR (CDCl ₃ , 500 MHz): 7.31 (br s, 10H), 2.43 (d, 4H), 1.95-1.2

Example  One

A continuous multi-stage CSTR reactor (see FIG. 1) composed of two 0.2 m ³ capacity reactors, a flash vessel and a post reactor was used.

In the first reactor, hexane was injected at 28 kg / hr, ethylene at 8 kg / hr hydrogen at 4.0 g / hr, nitrogen at 0.1 kg / hr, and triethylaluminum (TEAL) at a flow rate of 30 mmol / hr, Was injected at a rate of 1 g / hr (180 μmol / hr). At this time, the first reactor was maintained at 84 ° C., the pressure was maintained at 9 bar, the residence time of the reactant was maintained at 2.5 hours, and the slurry mixture containing the polymer was continuously supplied to the flash vessel vessel.

The slurry mixture was introduced into a flash vessel to discharge gas including hydrogen, nitrogen and ethylene, and the slurry mixture containing the polymer collected in the lower layer was successively passed to the second reactor.

The molecular weight adjuster prepared in Preparation Example 4 was fed into a second reactor at a flow rate of 23 kg / hr of hexane, 6 kg / hr of ethylene, 90 cc / hr of 1-butene and 25 mmol / hr of triethylaluminum (TEAL) / hr. &lt; / RTI &gt; The second reactor was maintained at 80 DEG C, the pressure was maintained at 7 bar, the residence time of the reactants was maintained at 1.5 hours, and the polymer mixture was continuously passed through a post reactor while maintaining a constant level in the reactor .

The post reactor was maintained at 78 DEG C, and unreacted monomers were polymerized. The polymerization product was then made into the final polyethylene via a solvent removal unit and dryer. The prepared polyethylene was mixed with 1000ppm of calcium stearate (Hibon Industries) and 2000ppm of 21B (Songwon Industry) and then made into pellets.

Example  2

A continuous multi-stage CSTR reactor (see FIG. 1) composed of two 0.2 m ³ capacity reactors, a flash vessel and a post reactor was used.

In the first reactor, hexane was injected at 31 kg / hr, ethylene at 9 kg / hr hydrogen at 4.5 g / hr, nitrogen at 0.1 kg / hr, and triethylaluminum (TEAL) at 30 mmol / hr, Was injected at a rate of 1 g / hr (180 μmol / hr). At this time, the first reactor was maintained at 84 ° C., the pressure was maintained at 9 bar, the residence time of the reactant was maintained at 2.5 hours, and the slurry mixture containing the polymer was continuously supplied to the flash vessel vessel.

The slurry mixture was introduced into a flash vessel to discharge gas including hydrogen, nitrogen and ethylene, and the slurry mixture containing the polymer collected in the lower layer was successively passed to the second reactor.

The molecular weight adjuster prepared in Preparation Example 4 was fed into a second reactor at a flow rate of 23 kg / hr of hexane, 6 kg / hr of ethylene, 90 cc / hr of 1-butene and 25 mmol / hr of triethylaluminum (TEAL) / hr. &lt; / RTI &gt; The second reactor was maintained at 80 DEG C, the pressure was maintained at 7 bar, the residence time of the reactants was maintained at 1.5 hours, and the polymer mixture was continuously passed through a post reactor while maintaining a constant level in the reactor .

The post reactor was maintained at 78 DEG C, and unreacted monomers were polymerized. The polymerization product was then made into the final polyethylene via a solvent removal unit and dryer. The prepared polyethylene was mixed with 1000ppm of calcium stearate (Hibon Industries) and 2000ppm of 21B (Songwon Industry) and then made into pellets.

Example  3

A continuous multi-stage CSTR reactor (see FIG. 1) composed of two 0.2 m ³ capacity reactors, a flash vessel and a post reactor was used.

Hydrogen was injected into the first reactor at a flow rate of 35 kg / hr of hexane, 10 kg / hr of hydrogen, 0.1 kg / hr of nitrogen, and 40 mmol / hr of triethylaluminum (TEAL) Was injected at a rate of 1 g / hr (180 μmol / hr). At this time, the first reactor was maintained at 84 ° C., the pressure was maintained at 9 bar, the residence time of the reactant was maintained at 2.5 hours, and the slurry mixture containing the polymer was continuously supplied to the flash vessel vessel.

The slurry mixture was introduced into a flash vessel to discharge gas including hydrogen, nitrogen and ethylene, and the slurry mixture containing the polymer collected in the lower layer was successively passed to the second reactor.

In a second reactor, 21 kg / hr of hexane, 6.5 kg / hr of ethylene, 80 cc / hr of 1-butene and 20 mmol / hr of triethylaluminum (TEAL) 80 [mu] mol / hr. The second reactor was maintained at 80 DEG C, the pressure was maintained at 7 bar, the residence time of the reactants was maintained at 1.5 hours, and the polymer mixture was continuously passed through a post reactor while maintaining a constant level in the reactor .

The post reactor was maintained at 78 DEG C, and unreacted monomers were polymerized. The polymerization product was then made into the final polyethylene via a solvent removal unit and dryer. The prepared polyethylene was mixed with 1000ppm of calcium stearate (Hibon Industries) and 2000ppm of 21B (Songwon Industry) and then made into pellets.

Comparative Example  One

The procedure of Example 1 was repeated except that nitrogen was not added in Example 1.

Comparative Example  2

Hydrogen was fed into the first reactor at a flow rate of 28 kg / hr of hexane, 7 kg / hr of hydrogen and 3.5 mmol / hr of triethylaluminum (TEAL) at a flow rate of 30 mmol / hr, The catalyst was injected at 0.5 g / hr (180 μmol / hr). At this time, the first reactor was maintained at 84 ° C., the pressure was maintained at 9 bar, the residence time of the reactant was maintained at 2.5 hours, and the slurry mixture containing the polymer was continuously supplied to the flash vessel vessel.

The post reactor was maintained at 78 DEG C, and unreacted monomers were polymerized. The polymerization product was then made into the final polyethylene via a solvent removal unit and dryer.

[Test Example]

The physical properties of the polyethylene produced or used in Examples 1 to 3 and Comparative Examples 1 and 2 were measured by the following methods, and the results are shown in Table 1 below.

* Molecular weight (MW): Measured by weight average molecular weight using Gel Permeation Chromatography (GPC).

* Polydispersity (PDI): The weight average molecular weight was determined by dividing the number average molecular weight by gel permeation chromatography (GPC).

* Melt Index (MI): measured according to ASTM D1238.

R1 MI: The slurry in the first reactor was dried to take the polyolefin and measured according to ASTM D1238.

Density: measured according to ASTM D792.

Flexural Strength: Measured according to ASTM D790.

* Stress cracking resistance: Measured according to ISO 16770 at a temperature of 80 캜 and a pressure of 3.5 MPa.

* Die swell (%): The pelletized product was cut by scissors with a parison of 15.7 cm vertically passing through a blow molding machine (KRUPP KAUTEX, GERMANY) and measuring its weight.

Die Swell (%) =

As = Vsp x W / L

As: Average cross-sectional area of parison (cm &lt; ² &gt;) during scissor interval (15.7 cm)

Ad: sectional area of the die gap (0.6726 cm ² )

Vsp: non-melting volume when polyethylene is not filled

Specification melting volume (1.32 cm ³ / g)

* Sagging time (seconds): The time taken for the molten resin falling vertically through a blow molding machine to reach 126.5 cm was measured.

division Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 polymerization Continuous / multi-stage Continuous / multi-stage Continuous / multi-stage Continuous / multi-stage Continuous / 1st stage Ethylene
(kg / hr) 14 15 16.5 14 7 Nitrogen / first reactor ethylene
(g / kg) 12.5 11.1 10 0 - Molecular weight regulator
(μmol) 80 80 80 80 - Copolymer
(cc / hr) 90 90 80 90 - R1 MI (@ 5kg) 300 300 30 300 300 MI (@ 2kg) 0.30 0.38 0.18 1.11 90 MI (@ 5kg) 1.28 1.62 0.88 3.73 300 MI (@ 21.6kg) 34.0 39.2 16.0 71.0 - MFR 110 100 89   64 - MW 262,200 245,500 215,100 165,900 55,000 PDI 17.6 16.6 9.0 12.2 - Density (kg / m ³ ) 0.954 0.955 0.955 0.960 - Flexural strength
(MPa) 1390 1410 1350 1420 - Stress cracking resistance
(FNCT) 40 35 30 5 - Die Swell (%) 200 190 180 150 - Sagging Time
(second) 22 22 24 18 - Formability (Appearance) Good Good Good Good -
(Not processed)

As shown in Table 1, the polyethylene according to Examples 1 to 3 of the present invention had a very high molecular weight and polydispersity index (PDI) as compared with the polyethylene of Comparative Examples 1 and 2 prepared without the addition of nitrogen in the first reactor can confirm. That is, when the melt index of the polyethylene in the first reactor is sufficiently increased but the nitrogen is not supplied at the same time, the activity of the metallocene supported catalyst is not sufficiently maintained in the second reactor. However, It can be seen that the molecular weight is increased and the parison deflection time and stress cracking resistance are improved by being sufficiently maintained in the second reactor.

Further, as shown in Comparative Example 2 (MI: 300), the molecular weight of the material produced in the first reactor was greatly reduced, and as shown in Examples 1 to 3, the MI or molecular weight of the final product was appropriately controlled, Can produce high-quality products.

Example  4: Experiment to verify the effect of nitrogen

The 5L high-pressure reactor was exchanged with nitrogen for 1 hour at 60 ° C, and then 3L of hexane was added thereto. 1.8 ml of triethylaluminum (1M in hexane) for the purpose of removing water was injected, and 30 mg of the catalyst prepared in Preparation Example 3 was suspended in hexane and introduced through a sample container connected to the reactor. Also, the sample container connected to the reactor was replaced with nitrogen, and the valve was opened with the nitrogen gas of 5 bar and 70 ml filled, and the reactor was charged. Thereafter, ethylene was continuously charged at 30 DEG C and polymerization was carried out for 2.5 hours while maintaining the pressure at 9 bar. The temperature was lowered to 40 占 폚, ethylene and nitrogen in the reactor were removed, and the reactor temperature was further raised to 70 占 폚. The reactor was continuously charged with ethylene and polymerized for 1.5 hours while keeping the pressure at 9 bar. Thereafter, the temperature was lowered, the internal gas was removed, and the resultant was separated and dried. FIG. 2 is a graph showing the measured amounts of ethylene and the cumulative amount of ethylene in ml in units of ethylene.

Comparative Example  3: Experiment to verify the effect of nitrogen

The procedure of Example 4 was repeated except that no nitrogen was introduced into the reactor through the sample vessel before the ethylene introduction. FIG. 2 is a graph showing the measured amounts of ethylene and the cumulative amount of ethylene in ml in units of ethylene.

As shown in FIG. 2, when an inert gas is initially introduced to perform a multistage reaction, it can be seen that the catalyst unilaterally absorbs ethylene and converts it into polyethylene in the first step reaction. Thus, in the second step reaction, Can be seen. However, when nitrogen is not added, the catalyst absorbs ethylene rapidly in the first step reaction, so that the second step reaction does not sustain the activity and absorbs less ethylene.

Claims (20)

A method for producing polyethylene by reacting an ethylene monomer with a catalyst in a reactor in which a first reactor and a second reactor are connected in series,
(i) reacting an ethylene monomer and a catalyst in the presence of a metallocene supported catalyst and an inert gas in a first reactor to produce a low molecular weight ethylene polymer;
(ii) transferring the slurry mixture comprising the low molecular weight ethylene polymer to a flash vessel to discharge an inert gas and a gas comprising ethylene; And
(iii) further adding an ethylene monomer to the slurry mixture in the presence of a molecular weight regulator in a second reactor and reacting to prepare a high molecular weight ethylene polymer;
Wherein the weight average molecular weight of the low molecular weight polyethylene is 10,000 to 100,000 and the weight average molecular weight of the high molecular weight polyethylene is 150,000 to 300,000. The method according to claim 1,
Wherein said inert gas is nitrogen. The method according to claim 1,
Wherein the weight ratio of the inert gas to ethylene is from 1:10 to 1: 100. The method according to claim 1,
Wherein the inert gas is a mixed gas further comprising from 0 to 5% by weight of hydrogen. The method according to claim 1,
Wherein the metallocene supported catalyst is a mixed metallocene supported catalyst comprising a support, a first metallocene compound, a second metallocene compound, a first co-catalyst and a second co-catalyst. Gt; 6. The method of claim 5,
Wherein said support is selected from the group consisting of silica, silica-alumina and silica-magnesia. 6. The method of claim 5,
Wherein the first co-catalyst is an aluminum-containing organometallic compound represented by the following formula (1).
[Chemical Formula 1]
- [Al (R ¹ ) -O-] _n -
In Formula 1, R ¹ is the same or different from each other a halogen radical, hydrocarbyl radical of 1 to 20 carbon atoms substituted with a halogen or a hydrocarbyl radical having 1 to 20, n is an integer of 2 or more. 6. The method of claim 5,
Wherein the second co-catalyst is a boron-containing borate compound represented by the following formula (2).
(2)
T ⁺ [BQ ₄ ] ^-
Wherein T ⁺ is a polyatomic ion of +1 valence, B is boron of the +3 type oxidation state, and each Q is independently selected from the group consisting of hydride, dialkylamido, halide, alkoxide, aryloxide, hydrocarbyl, halo Carbyl and halo-substituted hydrocarbyl radicals, wherein Q has not more than 20 carbons, and when Q is a halide, said halide is one. 6. The method of claim 5,
Wherein the first metallocene compound is a compound represented by Formula 3 and the second metallocene compound is a compound represented by Formula 4 below.
(3)

[Chemical Formula 4]

Wherein R ^m and R ⁿ are the same or different hydrogen radicals, alkyl of 1 to 20 carbon atoms, cycloalkyl, aryl, alkenyl, alkylaryl, arylalkyl, arylalkenyl radical or alkylsilyl radical , R ¹ and R ² are the same or different from each other, or a hydrocarbyl radical having 1 to 6 carbon atoms, and a, a ', b or b' each represent an integer of 1 to 4,
M is a transition metal of group 4B, 5B or 6B of the periodic table and Q is a halogen radical or an alkyl radical alkenyl radical of 1 to 20 carbon atoms, an aryl radical alkylaryl radical, an arylalkyl radical or an alkyl radical of 1 to 20 carbon atoms Lt; / RTI &gt;
B is any one selected from the group consisting of an alkyl radical having 1 to 4 carbon atoms or a hydrocarbyl radical containing silicon, germanium, phosphorus, nitrogen, boron or aluminum,
J is any one selected from the group consisting of NR ⁵ , O, PR ^5, and S, and R ⁵ is an alkyl radical or a substituted alkyl radical having 1 to 20 carbon atoms,
Provided that any hydrogen radical present in R ^m , R ⁿ , B or R ⁵ is alkoxy, aryloxy, alkylthio, arylthio, amino, phenyl or substituted phenyl having 1 to 20 carbon atoms, Alkoxy. The method according to claim 1,
An organoaluminum compound selected from the group consisting of trialkylaluminum, dialkylaluminum halide, alkylaluminum dihalide, aluminum dialkylhydride and alkylaluminum sesquihalide is further added to the first reactor or the second reactor so that moisture in the reactor Is removed. The method according to claim 1,
Wherein the molecular weight modifier is an organometallic complex compound prepared by reacting a cyclopentadienyl metal compound represented by the following formula (5) with an organoaluminum compound represented by the following formula (6).
[Chemical Formula 5]
Cp ¹ Cp ² MX ₂
In the formula (5), Cp ¹ and Cp ² independently represent a cyclopentadienyl, an indenyl, a fluorenyl group or a derivative thereof as a ligand, M is titanium, zirconium or hafnium, and X is a halogen element.
[Chemical Formula 6]
R ¹ R ² R ³ Al
In Formula 6, R ¹ , R ^2, or R ³ is independently a C 1 to C 20 alkyl substituent or a halogen. 12. The method of claim 11,
Wherein the M content of the organometallic complex is 0.001 μmol / kg to 10 μmol / kg, based on 1 kg of total ethylene fed into the reactor. The method according to claim 1,
And a comonomer is further added to the second reactor. The method according to claim 1,
Wherein the residence time of the polymerization step in the first reactor is 1 to 3 hours. The method according to claim 1,
Wherein the residence time of the polymerization step in the second reactor is 1 to 3 hours. The method according to claim 1,
Wherein the reaction temperature of the polymerization step of the first reactor is from 70 to 90 DEG C and the reaction pressure is from 8 to 10 bar. The method according to claim 1,
Wherein the reaction temperature of the polymerization step of the second reactor is 60 to 90 DEG C and the reaction pressure is 6 to 9 bar. The method according to claim 1,
The flash vessel comprises a valve of a first reactor controlled to 9 bar or more and a valve of a second reactor controlled to 7 bar or more, the temperature is 70 to 90 ° C, and the time required for gas discharge is 5 to 30 minutes Wherein said polyolefin resin is a polyolefin resin. The method according to claim 1,
Wherein the low-molecular-weight polyethylene has a polydispersity of 1.5 to 5.0 and a melt index of 5 kg and a melt viscosity of 1,000 to 10 at 190 ° C. The method according to claim 1,
Wherein the high-molecular-weight polyethylene has a polydispersity of 5 to 20, a melt index of 5 kg and a melt index of 10 to 0.1 at 190 ° C.

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