KR20100025078A - Preparation method of a catalyst for polyolefin copolymerization and method for polymerizing polyolefin using a catalyst produced by the same - Google Patents

Abstract

PURPOSE: A preparation method of a metallocene-supported catalyst for polyolefin copolymerization is provided to minimize the content of powder within circulation gas flow by reducing the generation rate of pulverized powder in gas phase polymerization. CONSTITUTION: A preparation method of a metallocene-supported catalyst for polyolefin copolymerization comprises the steps of: (i) dissolving a crosslinking bisindenyl-based metallocene catalyst component, wherein the molar ratio of aluminum among alkylaluminoxane : transition metals among metallocene catalyst components is 150~600 : 1; (ii) adding the solution of (i) step to carrier slurry and stirring the mixture at 40~160 °C to support alkylaluminoxane and metallocene component; (iii) pouring supernatant and washing the supported catalyst at -10~25 °C; and (iv) collecting catalyst powder by drying the washed catalys, wherein the transition metal content in metallocene supported catalysts is 0.1~0.3 weight% and the content of aluminum is 13 weight% or greater.

Description

FIELD OF THE INVENTION A method for preparing a metallocene supported catalyst for polyolefin polymerization and a polyolefin polymerization method using a metallocene supported catalyst prepared thereby

The present invention relates to a method for preparing a highly active metallocene supported catalyst for polyolefin polymerization by supporting an alkylaluminoxane and a metallocene compound on a porous inorganic support, and a polyolefin polymerization method using the metallocene supported catalyst prepared thereby. More specifically, during gas phase polymerization, by effectively dispersing the reaction heat, sheet formation due to overreaction is prevented, and the amount of fine powder in the circulating gas stream is reduced, and the amount of static electricity generated is also reduced by reducing the amount of fine powder. The present invention relates to a method for preparing a metallocene supported catalyst for polyolefin polymerization capable of stably controlling a gas phase reaction, and a polyolefin polymerization method using a metallocene supported catalyst prepared thereby.

Metallocenes can be represented by the empirical L _n MQ _p , where M is a metal of Group IIIB, IVB, VB or VIB; Q is a hydrocarbyl group or halogen having 1 to 20 carbon atoms; p is valence-2 of M, and L is a ligand bound to the metal M. This metallocene compound is used together with the alkylaluminoxane which is a promoter, especially methylaluminoxane, and an olefin polymer and a copolymer are manufactured.

The metallocene catalyst must be supported on an appropriate support in order to be used in a fluidized bed reactor or slurry reactor, and the individual catalyst particles loaded with metallocene must exhibit sufficient activity so as not to cause problems due to catalyst support residues. The activity of the supported catalyst is proportional to the amount of the metallocene component supported. However, the amount of the metallocene component to be supported should be optimized according to the mechanical properties of the support, the amount and form of the alkylaluminoxane supported together, and the type of polymerization reaction. This is because the high rate of poison does not show the proper activity, resulting in a problem of deterioration of the physical properties of the final product due to catalyst and carrier residues. This is because the carrier becomes unacceptable, resulting in an increase in fines due to local sheet formation and cleavage of the carrier.

Representative metallocene supported catalyst production method currently developed and used is a method in which a metallocene catalyst is supported on silica together with methylaluminoxane, which reacts the hydroxy group of the silica with methylaluminoxane to the surface of the silica. It is a method of supporting a methylaluminoxane and carrying a metallocene catalyst on the supported methylaluminoxane. The metallocene catalyst component may be supported simultaneously with the methylaluminoxane or through additional reaction after the methylaluminoxane is supported. As a method for preparing a metallocene supported catalyst, a method of adding a mixture of alkylaluminum such as trimethylaluminum or triethylaluminum to dehydrated silica and then introducing metallocene (see US Patent No. 4,937,217), Trimethylaluminum is added to silica that is not dehydrated, and then metallocene is introduced to dry and supported (see US Pat. Nos. 4,912,075, 4,937,301 and 4,935,397), and trimethylaluminum is added to silica to which water is added. To produce aluminoxane in the carrier pores and then to carry metallocene (see US Pat. Nos. 5,008,228, 5,086,025 and 5,147,949), after calcining the inert carrier silica, the metallocene and the activating material Supporting methods (see US Pat. Nos. 4,808,561, 4,897,455 and 4,701,432) and the like are known. In addition, a method of mixing metallocene and alkylaluminum and then adding dehydrated silica (US Pat. No. 5,238,892), first, preparing a mixed solution of metallocene and aluminoxane, and adding a porous carrier to the solvent, Method of preparing a catalyst precursor suitable for pre-polymerization by removing (US Pat. No. 5,240,894) and using only a mixed solution of metallocene and aluminoxane corresponding to the micropore volume (US Pat. No. 6,090,740 and US Patent No. 5,721,740 and the like have been published.

However, when a metallocene supported catalyst is prepared and used in a fluidized bed gas phase polymerization process by these methods, the metallocene catalyst, unlike the existing Ziegler catalyst, exhibits a phenomenon in which the reaction stability is greatly reduced. This decrease in reaction stability is due to two phenomena, one of which is an increase of static electricity and the other of an increase in fine powder, which increases the phenomenon that catalyst particles and polymers adhere to the reactor wall. The heat removal capacity at the part is lowered, and the reaction is performed at a local temperature rise, eventually forming a molten sheet, which leads to a state in which normal operation cannot be performed. Fine powder deposition and entrainment into the circulating gas line are intensified, and fine powder is attached to the heat exchanger and compressor of the circulating gas line to form sheets or to reduce the heat removal capacity, and eventually to lower the flow capacity. It is a factor that makes driving impossible. Both of these phenomena are due to the fact that the metallocene supported catalyst has different characteristics from the typical magnesium chloride supported Ziegler-Natta catalyst.

In the case of most Ziegler catalysts for polyethylene polymerization, the active metal species has a supported ratio of 3 to 7% by weight, and when the metal species is titanium, it has a supported ratio of 0.5 to 1.5 mmol / g-catalyst and a metallocene supported catalyst. In the case of, the supporting ratio of the active metal species is in the range of 0.1 to 0.5% by weight, and when the metallic species is zirconium, it has a supporting ratio of 0.01 to 0.05 mmol / g-catalyst. Therefore, the molar loading rate is at least 10 times and as much as 150 times. This means that when the supported metallocene catalyst has the same level of activity per gram as the Ziegler catalyst, each supported metallocene active point has a very high activity. It is noted that the rate of polymer growth can be very harsh conditions locally. Therefore, if the distribution of the active site in the carrier is biased or the pore structure of the carrier in which the active point is distributed is not suitable for exothermic and polymer growth, it is possible to cause the increase of fine powder due to melt sheet formation due to local exotherm or cleavage of the carrier. This is high. In addition, silica, which is mainly used as a carrier of the metallocene catalyst, has a higher charge rate than magnesium chloride, which is used as a carrier of the Ziegler catalyst, to generate more static electricity in the gas phase fluidized bed reactor. This will deepen the wall attachment.

In order to solve this problem, US Patent Nos. 5,629,253 and 6,201,076 disclose a method of suppressing reactor fouling by injecting an antistatic agent together with a metallocene supported catalyst into a slurry polymerization reactor. European Patent EP 0 811 638 A2 has a method of using an antistatic agent in the gas phase fluidized bed reactor up to 10 to 2000 parts by weight based on the bed weight, US Patent No. 6,562,924, pre-treated with 150 parts by weight of an antistatic agent when preparing a supported catalyst, polymerization A method of injecting 50 parts by weight of the same antistatic agent on the basis of olefins injected into the reactor is described. In addition, US Pat. No. 5,283,278 shows a method of using a mixed antistatic agent in the prepolymerization of a metallocene supported catalyst. US Pat. No. 6,946,530 shows an antistatic agent in a gas phase fluidized bed reactor of less than 20 parts by weight. Use with 10 parts by weight of ₂ O ₂ It was confirmed that the static electricity can be reduced without reducing the activity.

However, in the use of the antistatic agent, excessive use of the antistatic agent has the side effect of lowering the overall activity of the catalyst, it is difficult to achieve the desired effect due to the problem of dispersion in small amounts, oils or hydrocarbons which are diluents for dilution use for a small amount injection It also accumulates in the system and acts as a factor that makes weather operation difficult. In addition, the antistatic agent only serves to reduce the overall state of charge in the reactor is not a great help in controlling the reaction at the microscopic level of the catalyst. Therefore, for stable operation of the gas phase fluidized bed reactor, a technique capable of controlling the amount and loading state of the metallocene catalyst component at the catalyst level is required.

An object of the present invention is to solve the above-mentioned problems, to prevent the formation of sheets due to over-reaction during gas phase polymerization, and to reduce the amount of fine powder generated in the circulating gas stream, The present invention relates to a method for preparing a metallocene supported catalyst for polyolefin polymerization capable of stably controlling a gas phase reaction by reducing an amount of static electricity generated, and a polyolefin polymerization method using a metallocene supported catalyst prepared thereby.

Method for preparing a metallocene supported catalyst for polyolefin polymerization according to the present invention is characterized in that it comprises the following steps:

(1) dissolving the metallocene catalyst component in a solution of alkylaluminoxane,

(2) adding the solution of step (1) to the carrier slurry, stirring at 40-160 ° C. to support the alkylaluminoxane and the metallocene catalyst component,

(3) after the supporting reaction in step (2), after decanting the supernatant of the solution, washing the obtained supported catalyst with an organic solvent at -10 ~ 25 ℃,

(4) 단계 drying the washed catalyst of step (3) and recovering it as a catalyst powder.

In the method for preparing a metallocene supported catalyst for polyolefin polymerization according to the present invention, the metallocene catalyst component used in step (1) is not particularly limited in kind, but is preferably represented by the following formula (I) Has the structure shown.

(THI) ₂ R "MQ _p (I)

In the above formula (I), THI is a substituted or unsubstituted tetrahydroindenyl derivative, and R ″ is a structural crosslink that imparts steric stiffness between two THI groups; M is Group IIIB, Group IVB, Group VB Or a transition metal selected from group VIB, Q is a hydrocarbyl group or halogen having 1 to 20 carbon atoms, and p is valence-2 of M.

In the metallocene catalyst of formula (I), the two THI ligands may be the same or different, but the same is preferable.

Substitution patterns and numbering of the ligands of the catalyst of the invention are described in detail below.

When THI is substituted, this means that any position on THI may contain a substituent instead of a hydrogen atom. Thus, each substituted THI ligand may have a substituent on the 5-membered ring, a substituent on the 6-membered ring, or a substituent on both 5- and 6-membered rings.

Substituent positions of the THI ligands in the specification of the present invention are numbered 1 to 7 by the following notation system.

In order to distinguish the substitution in the first THI ligand and the second THI ligand of the two THI ligands, the second THI ligand is numbered by the same system as above, but is numbered 1'-7 '. In this type of catalyst, the position of the crosslinking of the two THI ligands is not particularly limited and is preferably 1,1'-crosslinked, 2,2'-crosslinked or 1,2'-crosslinked, 1,1 ' Crosslinking is most preferred.

The position of the substituent (s) on the two THI ligands is not particularly limited, but at least one THI ligand is substituted at the 2-position and / or 4-position (or 2'-position and / or 4'-position) It is preferable.

In one preferred embodiment, both THI ligands can be substituted. In this case, it is preferred to include substituents at the 2-position (2'-position) and / or 4-position (4'-position) of both THI ligands, and to the 2-position (2) of both THI ligands. Most preferably, they include a substituent at the '-position) and the 4-position (4'-position), and other positions in the THI ring may be substituted or unsubstituted.

Particularly preferred metallocene catalysts having 1,1'-crosslinking are 2; 4; 2,4; 2,2 '; 4,4 '; 2,4 '; 2,4,2 '; 2,4,4 '; And a substitution pattern of 2,4,2 ', 4', and only the positions indicated above include substituents. Here, since the basic structure of the two THI ligands is the same, for example, the substitution patterns of 2,4 'and 4,2' are the same THI substituent structure.

The kind of substituent (s) present on the THI ligand is not particularly limited, and when the THI ligand includes two or more substituents, these THI ligands may be substituted with the same substituents or different substituents.

Preferably, the substituents are independently selected from hydrocarbyl groups, alkyl groups, alkylsilicon groups, alkoxy groups, cycloalkyl groups, aryl groups and halogens having 1 to 20 carbon atoms. Examples thereof include phenyl (Ph), benzyl (Bz), naphthyl (Naph), indenyl (Ind) and benzindenyl (BzInd), methyl (Me), ethyl (Ethyl), n-propyl (n- Pr), i-propyl (i-Pr), n-butyl (n-Bu), t-butyl (t-Bu), trimethylsilicon group (Me ₃ Si), alkoxy (preferably RO, where R is C _1-20 alkyl), cycloalkyl and the like, and halogen. The most preferred substituent at the 2-position of THI is a methyl group. Most preferred substituents at the 4-position of THI are phenyl, naphthyl or benzindenyl.

In one preferred embodiment, examples of THI derivative ligands include 2-Me, 4-PhTHI; 2-Me, 4-NaphTHI; Or 2-Me, 4,5-BzIndTHI.

The type of R ″, which is a crosslinking present between two THI rings in the metallocene catalyst component of formula (I), is not particularly limited, but is preferably an alkylidene group having 1 to 20 carbon atoms , Alkylenyl group, germanium group (eg dialkylgernium group), alkylsilicon group (eg dialkylsilicon group), siloxane group (eg dialkylsiloxane group), alkylphosphine group or amine group Most preferably, ethylenyl radical (-CH ₂ CH _2- ) or Me ₂ Si.

The metal M in the metallocene catalyst of formula (I) is a transition metal selected from group IIIB, IVB, VB or VIB of the periodic table of the elements, preferably selected from Ti, Zr, Hf and V.

Q in the metallocene catalyst of formula (I) is preferably halogen, in particular Cl.

And since the valence of the said metal M is four, p becomes 2 normally.

The most preferred metallocene catalyst components used in the present invention are as follows:

Et (THI) ₂ ZrCl ₂ ,

Me ₂ Si (THI) ₂ ZrCl ₂ ,

Me ₂ Si (2-MeTHI) ₂ ZrCl ₂ ,

Et (2-MeTHI) ₂ ZrCl ₂ ,

Me ₂ Si (2-Me, 4-PhTHI) ₂ ZrCl ₂ ,

Et (2-Me, 4-PhTHI) ₂ ZrCl ₂

Me ₂ Si (2-Me, 4-NaphTHI) ₂ ZrCl ₂ ,

Et (2-Me, 4-NaphTHI) ₂ ZrCl ₂ ,

Me ₂ Si (2-Me, 4,5-BzIndTHI) ₂ ZrCl ₂ ,

Et (2-Me, 4,5-BzIndTHI) ₂ ZrCl ₂ .

The catalyst system of the present invention is not particularly limited, but may include one or more metallocene catalyst components as described above. It may also further comprise other known catalyst components in addition to the additional catalyst, if desired, for example the metallocene catalyst component according to the invention.

Metallocene catalyst components used in the present invention are described in W. Spalek; A. Antberg, J. Rohrmann, A. Winter, B. Bachmann, P. Kiprof, J. Behm, and W. A. Hermann, Angew. Chem. Int. Eng. Ed. 1992, 31, 1347, or commercially available from mCAT GmBH (Geschuftfuhrer Dr Markus Ringwald Handelsregister Freiburgi HRB 381812).

The alkylaluminoxane used in step (1) includes a straight chain and / or cyclic alkylaluminoxane oligomer, and when the alkylaluminoxane is a straight chain alkylaluminoxane oligomer, the formula R- (Al (R) -O) _n- AlR ₂ , and in the case of cyclic alkylaluminoxane oligomers, represented by the formula (-Al (R) -O-) _m , where R is a C ₁ -C ₈ alkyl group, preferably methyl and n are 1-40, Preferably it is 10-20, m is 3-40, Preferably it is 3-20. The alkylaluminoxane is a mixture of oligomers having a very wide molecular weight distribution, usually having an average molecular weight of about 800 to 1200, mainly maintained in solution in toluene, and in particular, 10% or 30% methylaluminum produced by Albemarle. Noxic acid, and the like.

In the solution resulting from the above step (1), the concentration of the alkylaluminoxane is 5 to 30% by weight, and the concentration of the metallocene catalyst component is preferably 0.001 to 0.5% by weight, calculated as the transition metal element (M). In addition, the molar ratio of the transition metal in the aluminum and metallocene catalyst components in the alkylaluminoxane is preferably from 1 to 600: 1 for aluminum, preferably from 150 to 600: 1, and the concentration of each component is in the above range. Outside of this, the activity is lowered, which is not preferable.

The solution comprises an aromatic hydrocarbon, aliphatic hydrocarbon or aliphatic ring hydrocarbon as solvent.

In the method for preparing a metallocene supported catalyst for polyolefin polymerization according to the present invention, the carrier used in the step (2) is a solid particulate porous, preferably an inorganic material such as silicon and / or aluminum oxide. Most preferably, silica is present in the form of spherical particles, for example particles obtained by a spray drying method, and has other functional groups containing OH groups or active hydrogen atoms.

The carrier has an average particle size of 10 to 250 microns, preferably an average particle size of 10 to 150 microns, a micropore volume of 0.1 to 10 ml / g, preferably 0.5 to 3 ml / g, and the surface area of the carrier. Is 5 to 1000 m 2 / g, preferably 50 to 600 m 2 / g.

When silica is used as the carrier, it should have at least a part of active hydroxy [OH] group, the hydroxy group concentration is preferably 0.7 ~ 1.6mmole / g per 1g of silica, if less than 0.7mmole supported amount of alkylaluminoxane It is not preferable because the activity decreases due to decrease, and when the content exceeds 1.6 mmol, the catalyst component is inactivated by OH, which is not preferable.

The hydroxyl group of the silica can be detected by IR spectroscopy, and the hydroxy group concentration on the silica is determined by contacting the silica sample with methylmagnesium bromide and measuring the amount of methane foamed (by pressure measurement).

Silicas having [OH] concentrations and physical properties suitable for the present invention include W.R., which has a surface area of 300 m 2 / g and a pore volume of 1.6 ml / g. The brand names XPO-2402, XPO-2410, XPO-2411 and XPO-2412 available from Grace and Company's Davison Chemical Division may be used, and silicas such as Davision® 948, 952 and 955 may be purchased and heated. Through the process can be used to adjust the desired concentration of [OH].

In the step (2), preferably, the alkyl aluminoxane is supported on the carrier, and then metallocene is supported. When silica is used as the carrier in step (2), the hydroxyl group of the silica is free of oxygen. Under anhydrous conditions, it reacts with alkylaluminoxanes to support the alkylaluminoxanes, providing a site on which the metallocenes will be supported, while being very sensitive to external catalyst poisons to protect metallocenes that tend to lose activity. Play a role. Therefore, the higher the supported amount of the alkylaluminoxane, the higher the supported amount of the metallocene, and the higher the probability of not being poisoned by the external catalyst poison, thereby increasing the activity.

The carrier slurry used in step (2) is prepared by suspending the carrier in a hydrocarbon solvent or a hydrocarbon solvent mixture.

The temperature of the supporting process of step (2) is preferably 40 ~ 160 ℃, more preferably 80 ~ 120 ℃, outside the temperature range, the activity is lowered and polymer aggregation occurs in the reactor is preferred It is preferable that the supporting time is 30 minutes to 4 hours, and more preferably 1 to 2 hours. If it is out of the above time range, the economical efficiency is low or the reaction is not sufficient, so that the function as a catalyst is not sufficient, which is not preferable. .

In the step (2), the weight ratio of aluminum / silica in the alkylaluminoxane is preferably 0.1 to 1.5 in view of catalytic activity and fine powder formation prevention.

A small amount of unreacted alkylaluminoxane and unsupported metallocene catalyst is present in the supported catalyst solution in which the supported process of step (2) is completed, and these need to be removed before the drying process, but unreacted alkylaluminoxane is not removed. In this case, the supported catalysts stick to each other and cause a poor injection problem when the catalyst is injected into the polymerization reactor in a dried form, and the injection of the agglomerated catalyst causes local overreaction in the reactor to form sheets and agglomerates. Will cause problems. In addition, the unsupported metallocene is easily separated from the carrier during the polymerization reaction to form a polymer of very fine particles, causing problems of reactor fouling.

For the purpose of removing these unsupported substances, in the step (3), the supported catalyst is washed with an organic solvent such as an aromatic hydrocarbon solvent or an aliphatic hydrocarbon solvent. In the washing step, unsupported metallocene and alkylaluminoxane are removed, and when desorption of the supported metallocene occurs in this step, it acts as an element degrading the activity of the supported catalyst. It is preferable to perform the washing step at a low temperature of 10-25 ° C.

Drying in the step (4) can be carried out using a conventional drying process.

The content of the transition metal (M) in the metallocene supported catalyst prepared according to the method of the present invention as described above is 0.1 to 0.3% by weight. If the content of the transition metal is less than 0.1% by weight, the catalytic activity is low, and a gel is generated during polymerization, which is not preferable. In addition, the aluminum content in the metallocene supported catalyst should be 13% by weight or more, so that the catalyst activity is excellently maintained.

The polyolefin polymerization method of the present invention using the metallocene supported catalyst for polyolefin polymerization prepared by the production method according to the present invention is hydrogen, olefin, in the presence of the metallocene supported catalyst prepared as described above as a main catalyst. An olefin polymer or copolymer is produced by reacting a gas phase polymerization composition comprising a comonomer, if necessary.

The polyolefin is an α-olefin homopolymer, a copolymer of α-olefin and α-olefin, a copolymer of α-olefin and diene, and the like, and preferably, high density polyethylene, linear low density polyethylene, ultra low density polyethylene, homo polypropylene, Propylene copolymers such as propylene ethylene copolymers, poly butadiene or butadiene ethylene copolymers and the like.

The α-olefin is preferably selected from the group consisting of ethylene, propylene, butene, hexene and octene, and the dienes are preferably butadiene, hexadiene or octadiene.

Preferably, the α-olefin may be ethylene, and in this case, the comonomer is preferably an alpha-olefin other than ethylene such as propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, or the like. The content ratio of the comonomer and ethylene is from 0.005 to 0.02 in molar ratio of comonomer / ethylene, preferably from 0.008 to 0.015. In this case, if the comonomer / ethylene molar ratio is less than 0.005 or more than 0.02, the desired level of copolymer cannot be obtained.

In such a method of preparing an olefin (co) polymer, the metallocene catalyst is combined with one or more activators to form an olefin polymerization catalyst system. Preferred activators used in this case include alkylaluminum compounds (e.g., diethylaluminum chloride), alkylaluminoxanes, modified aluminoxanes, neutral or ionic ionizing activators, noncoordinating anions, noncoordinating Group 13 metals or metalloid anions, Borane, borate, and the like.

With the alkyl aluminum compound has the general formula AlR _n X _(3-n) alkyl aluminum compounds represented by (wherein, R is an alkyl group of carbon number 1 ~ 16, X is a halogen element, and 1≤n≤3) Can be used. Specific examples of the alkyl aluminum compound are preferably triethyl aluminum, trimethyl aluminum, trinormal propyl aluminum, trinormal butyl aluminum, triisobutyl aluminum, trinormal hexyl aluminum, trinormal octyl aluminum, tri2-methylpentyl Aluminum etc. are used, Especially preferably, triisobutyl aluminum, triethyl aluminum, trinormal hexyl aluminum, or trinormal octyl aluminum is used.

It is preferable to use the said alkylaluminum compound at the time of gas phase superposition | polymerization in the following molar ratio according to desired polymer property.

1 ≦ transition metal in alkylaluminum compound / main catalyst ≦ 1000

More preferably

10 ≦ alkyl aluminum compound / transition metal in main catalyst ≦ 300

Most preferably

50 ≦ alkyl aluminum compound / transition metal in main catalyst ≦ 150

If the molar ratio of the transition metal in the alkylaluminum compound / main catalyst is less than 1 kPa, sufficient polymerization activity cannot be obtained, whereas if it exceeds 1000, the adverse effect of lowering the polymerization activity appears.

In the above olefin (co) polymer production method, the polymerization reaction is preferably in the absence of a hydrocarbon solvent, preferably at a temperature of 60 to 120 ° C, more preferably at 65 to 100 ° C, and most preferably at 70 to 80 ° C. Preferably it is carried out at a pressure of 2 to 40 atmospheres, more preferably 10 to 30 atmospheres.

If the polymerization temperature in the reactor is less than 60 ° C., sufficient polymerization efficiency cannot be obtained. If the polymerization temperature is more than 120 ° C., there is a problem that a polymer mass is easily generated. In addition, when the operation pressure in the reaction reactor is less than 2 atmospheres, the ethylene partial pressure is low to obtain sufficient polymerization efficiency. When it exceeds 40 atmospheres, control of the reaction becomes difficult, and the reactor is exerted.

In the above olefin (co) polymer production method, an antistatic agent can be further used. The antistatic agent serves to reduce the occurrence of static electricity to promote the discharge of particles to reduce the constant voltage in the reactor, specific examples thereof include tertiary amines, ethoxylated amines and polyether compounds, the tertiary amine Can be represented by the following formula:

R ¹ NR ² R ²

(R ¹ is hydrogen or a (linear or branched) alkyl group having 2 to 22 carbon atoms; R ² may be a hydroxyl group such as (CH ₂ ) _x OH radicals, where x is 1-50, preferably 2-2) Is an integer of 12).

Preferred antistatic agents are AS-700 (manufactured by Tokyo Chemical Co., Ltd.) having the formula C ₁₆ H ₃₃ N (CH ₂ CH ₂ OH) ₂ and AS700-L which is formula (C ₁₂ H ₂₅ N (CH ₂ CH ₂ OH) ₂ ) Is).

The antistatic agent can be injected into a fluidized bed reactor after being diluted with a suitable dilution solvent. As the dilution solvent, mineral oil may be used or hexane may be used. In the present invention, the antistatic agent is used in an amount of 10 to 500 parts by weight, preferably 20 to 300 parts by weight, and most preferably 30 to 150 parts by weight, based on 100 parts by weight of olefin injected into the gas phase reactor. It is preferable because the antistatic effect can be obtained without.

In the gas phase polymerization, the metallocene supported catalyst prepared by the production method of the present invention effectively disperses the heat of reaction during gas phase polymerization, thereby preventing sheet formation due to overreaction and reducing the amount of fine powder generated in the circulating gas stream. The amount of fine powder is small, and the amount of fine powder is reduced, and thus, the gas phase reaction can be stably controlled.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Example  One

[Preparation of supported metallocene catalyst]

Dehydrated silica of XPO-2402 (average particle size 50 microns, surface area 300 m2 / g, micropore volume 1.6 ml / g, OH concentration 1 mmol / g) was quantified under anhydrous conditions in a 1L reactor equipped with a stirrer and a cooling condenser. Injected. 75 ml of methylaluminoxane solution (10% by weight in toluene) was quantified in a measuring cylinder, and then mixed with 0.15 g of metallocene catalyst component Et (THI) ₂ ZrCl ₂ , which was pre-quantified in 250 ml Schlenk, at room temperature. The mixture was stirred for 5 minutes to dissolve and react with the solid metallocene catalyst. The silica was maintained in a slurry state using the methylaluminoxane-metallocene solution and 50 ml of the toluene solution before the reaction. The silica slurry and the methylaluminoxane-metallocene solution were mixed, and the reaction temperature was raised to 110 ° C while stirring. At this temperature, the supporting reaction proceeded for 90 minutes. After the reaction was completed, the reaction was transferred to a Schlenk vessel, followed by decantation. After the reaction was stirred, the mixture was allowed to stand for 10 minutes, followed by decantation of the upper solution, and the reaction was first washed with 100 ml of toluene at 25 ° C. After 10 minutes the top solution was decanted and washed twice with 100 ml of toluene at 25 ° C. The resulting catalyst system was then washed with purified hexane and then dried under mild vacuum. The amount of the supported catalyst prepared was 7.2 g. Al and Si content analysis of the catalyst were carried out to calculate the amount of methylaluminoxane supported from the Al content. The measured Al content was 14.4% by weight, and the amount of the supported methylaluminoxane was 31% by weight. Zr content analysis was carried out to check the content of the supported catalyst component, the Zr content was 0.17% by weight.

[Polymerization method]

The polymerization process was carried out in a continuous gas phase fluidized bed reactor as shown in FIG. 1. The gas phase fluidized bed reactor used in the embodiment of the present invention was equipped with a sensor to measure the electrostatic voltage in the system. The electrostatic sensor (ES 5002) located at the bottom of the fluidized bed is effective in indicating the degree of polymerization reaction in the reactor, particularly in the presence of sheets. The constant voltage in the reactor varies with the catalyst system used, usually with oscillations in the range of -2,000 volts and +2,000 volts. The magnitude of this amplitude indicates the degree of polymerization and whether or not the sheet is generated. The fluidized bed consisted of polymer particles.

A gaseous feed stream of ethylene and hydrogen and monomers were introduced into the recycle gas line under the reactor bed. 1-hexene was used as the comonomer. The flow rates of each of ethylene, hydrogen and comonomers were adjusted to maintain the desired constant composition. Ethylene concentration was adjusted to maintain a constant ethylene partial pressure. Hydrogen was adjusted to maintain a constant hydrogen to ethylene molar ratio. All gas concentrations were measured by on-line gas chromatography so that the composition of the recycle gas stream was relatively constant.

The prepared metallocene supported catalyst was directly injected into the fluidized bed. The feed rate of the catalyst was adjusted to maintain a constant polymer production rate. The reaction bed consisting of growing polymer particles was kept fluidized by the continuous flow of monomer supplements and recycle gas through the reaction bed. The reactor was operated at a total pressure of 19.2 Kgf / cm ² . In order to maintain a constant reactor temperature, the heat exchanger was adjusted by continuously raising or lowering the temperature of the recycle gas as the recycle gas passed to control the change in the exothermic rate caused by the polymerization. The fluidized bed was maintained at a constant height by recovering a portion of the bed at the same rate as the rate of formation of the particulate product. For the control of static electricity in the reactor, AS700-L was diluted to 10% by weight in hexane, and 40 parts by weight relative to the amount of ethylene injected. Triisobutylaluminum (TiBA) was used as a catalyst activator, and 50 parts by weight of the ethylene injection amount was injected.

The obtained product was discharged by the sequence operation by a series of valves, and the polymer discharged was obtained in a state in which unreacted monomers were removed from the degassing vessel and lost in activity through a steamer. . Gas phase polymerization using the catalyst was carried out under the standard polymerization conditions of Table 1 below.

As a result of the polymerization, as shown in Figure 4, the static (static) was stable, the activity of the supported catalyst in Example 1 came out as 5200g / g-catalyst, and bed turn over (BTO) of 17.2 for 9.1 days Recorded. The reaction was terminated by a planned reaction stop and the interior of the fluidized bed reactor was found to show no fouling or wall sheets, and the heat exchanger remained clean.

Table 1

Reaction condition Metallocene supported catalyst Temperature (℃) Pressure (kg G / cm ² ) Ethylene (mol%) BED Weight (kg) Residence Time (h) Formation Rate (kg / hr) MI Density Bulk Density (g / cc) 80 19.2 45 70 10.8 ~ 12.7 5.5 ~ 6.5 1 0.917 0.47

Example  2

Gas phase fluidized bed polymerization was carried out using the same metallocene supported catalyst as in Example 1, except that 15 parts by weight of TiBA, a reaction activator, was added during the gas phase polymerization reaction. In this case, the polymerization activity was raised to 6500 g / g-catalyst, the reaction was also maintained stable, and the static was also stable as shown in FIG. 5 during the reaction period. After 30.0 days of operation, the planned reaction was stopped. As a result of internal reactor inspection, no fouling or wall sheets were found, and the heat exchanger remained clean.

Example  3

The supported catalyst was prepared in the same manner except that 0.08 g of Et (THI) ₂ ZrCl ₂ was used in preparing the metallocene supported catalyst of Example 1. The content of Al supported was 14.5% by weight, and the content of Zr was 0.1% by weight. In the gas phase polymerization reaction, the same fluidized bed polymerization as in Example 1 was carried out except that the TiBA injection amount was treated at 15 parts by weight based on ethylene. As a result of the polymerization, the reaction was kept stable, and after 20.0 days of operation, the reaction was artificially or planned. As a result of internal reactor checks, no fouling or wall sheets were found, and the heat exchanger remained clean.

Activity was 3500 g / g-catalyst. As a result of internal reactor inspection, lumps on the wall sheet and the dispersion plate were found, weighing 20 kg.

Comparative example  One

The supported catalyst was prepared in the same manner except that 0.3 g of Et (THI) ₂ ZrCl ₂ was used in the preparation process of the metallocene supported catalyst of Example 1. The content of Al supported was 15.2% by weight, and the content of Zr was 0.37% by weight. The gas phase fluidized bed polymerization reaction was carried out in the same manner as in Example 1 using the supported catalyst. As a result of injecting the same level of antistatic agent AS700-L as in Example 1, the emergency reaction was terminated due to poor flow within 6.2 days after the discharge of the polymer. Total activity was 9300 g / g-catalyst. As a result of internal reactor inspection, lumps on the wall sheet and the dispersion plate were found, weighing 20 kg.

Comparative example  2

The fluidized bed gas phase polymerization reaction was carried out using the metallocene supported catalyst prepared in Comparative Example 1. AS700-L, an antistatic agent, was polymerized using 80 parts by weight based on ethylene flow rate and 30 parts by weight of TiBA. As a result of operation, emergency operation was stopped by generating seat in 2.6 days. Total activity was 8000 g / g-catalyst. Inspection inside the reactor revealed lumps on the wall sheets and the dispersion plate, weighing 35 kg.

TABLE 2

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Zr content (% by weight) 0.17 0.17 0.1 0.37 0.37 AS700-L (part by weight) 40 40 40 40 80 TiBA (parts by weight) 50 15 15 15 30 Hydrogen / ethylene 0.0011 0.0009 0.0009 0.0007 0.00085 1-hexene / ethylene 0.009 0.0095 0.0097 0.011 0.012 MI (190 ℃, 2.16kg) 3 One 1.0 2.2 1.03 density 0.9180 0.9170 0.9170 0.9208 0.9172 Active (g / g-catalyst) 5200 6500 3500 9300 8000 Driving time (day) 30.0 30.0 20 6.2 2.6 Operation Normal operation Normal operation Normal operation Emergency stop Emergency stop Reactor status No sheet No sheet Sheet Generation 20kg 20 kg of sheet generation 35kg sheet generation Fine content of less than 125㎛ (% by weight) 0.27 0.42 0.30 0.93 0.9 Al / Zr molar ratio of supported catalyst 240 240 543 132 132

As shown in Table 1, in the case of Example 1, it was shown that the gas phase polymerization reaction was stable by the control of the Zr content in the metallocene catalyst, in the case of Example 2 by controlling the amount of TiBA, the reaction activator It was found that the gas phase polymerization reaction was stably maintained even though the activity was maintained higher than that of Comparative Example 1.

On the other hand, in the case of Comparative Examples 1 and 3 having a high Zr content in the metallocene catalyst, it can be seen that the reaction is unstable to form a lump in the reactor. In the case of Comparative Example 1, even though the antistatic agent was used at the same level as Example 1, only a decrease in activity occurred, it showed that the reaction stability was not secured.

1 is a polymerization reaction facility of a polyolefin.

Claims (6)

A process for preparing a crosslinked bisdenyl-based metallocene supported catalyst for polyolefin polymerization, comprising the following steps: (1) dissolving the crosslinked bisindenyl metallocene catalyst component in a solution of alkylaluminoxane, wherein the molar ratio of transition metal in the aluminum: metallocene catalyst component in the alkylaluminoxane is 150-600: 1; (2) adding the solution of step (1) to the carrier slurry and stirring at 40-160 ° C. to support the alkylaluminoxane and the metallocene component; (3) after the supporting reaction in step (2), after decanting the supernatant of the solution, washing the obtained supported catalyst with an organic solvent at -10 ~ 25 ℃; And (4) 단계 drying the washed catalyst of step (3) and recovering it as a catalyst powder, wherein the content of the transition metal in the supported metallocene catalyst is 0.1 to 0.3% by weight, and the content of aluminum is 13% by weight That's it. The method for preparing a metallocene supported catalyst for polyolefin polymerization according to claim 1, wherein the metallocene catalyst component is represented by the following general formula (I): (THI) ₂ R "MQ _p (I) (Wherein THI is a tetrahydroindenyl derivative which may be substituted or unsubstituted, R ″ is a crosslinking present between two THIs, and M is a transition metal selected from Groups IIIB, IVB, VB and VIB) Q is a hydrocarbyl group or halogen having 1 to 20 carbon atoms, and p is valence-2 of M). The olefin or the olefin and the comonomer are polymerized by gas phase polymerization in the presence of the metallocene supported catalyst prepared by the method for preparing a metallocene supported catalyst for polyolefin polymerization according to claim 1. Polyolefin polymerization method. The polyolefin polymerization method according to claim 3, wherein the polyolefin is an alpha-olefin homopolymer, a copolymer of alpha-olefin and alpha-olefin, or a copolymer of alpha-olefin and dienes. The polyolefin polymerization method according to claim 3, wherein the polymerization reaction is performed by adding an antistatic agent during the polymerization. The method of claim 5, wherein the antistatic agent is of the formula R ¹ NR ² R ² Polyolefin polymerization characterized by: (R ¹ is hydrogen or a linear or branched alkyl group having 2 to 22 carbon atoms; R ² is a (CH ₂ ) _x OH radical, where x is an integer from 1 to 50). Way.

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