KR101019836B1 - Method for preparation of polyolefin by vapor phase polymerization - Google Patents

Abstract

The present invention relates to a gas phase polymerization method of polyolefin using an improved catalyst injection method in introducing a metallocene supported catalyst having a bulky ligand into a gas phase polymerization process.

Metallocene, vapor phase polymerization process. Catalyst injection method, oil slurry

Description

Gas phase polymerization method of polyolefin {METHOD FOR PREPARPARATION OF POLYOLEFIN BY VAPOR PHASE POLYMERIZATION}

The present invention relates to a gas phase polymerization method of polyolefin using an improved catalyst injection method in introducing a metallocene supported catalyst having a bulky ligand into a gas phase polymerization process.

The fluidized-bed gas phase polymerization reactor has many problems such as simplicity of reaction, low maintenance cost, and no need for monomer recovery process, but has a problem in that the catalyst is not properly dispersed during the control of the heat of polymerization and the catalyst injection into the fluidized bed.

Since metallocene catalysts can produce polymers of narrow molecular weight distribution, they have recently been introduced into a fluidized bed gas phase polymerization process and used to produce polymers of various improved properties. The metallocene catalyst may be introduced into a fluidized bed reactor by various methods. A method of directly injecting a homogeneous catalyst solution by dissolving in an organic solvent or supporting it on a carrier may be used.

Metallocene catalyst systems with bulky ligands are known to have a tendency to form fouling or sheets in the reactor when introduced into gas phase or slurry processes.

For example, in a gas phase polymerization reactor, a continuous gas stream is formed, which passes through the cooler and removes the heat of reaction, which fouling reduces the efficiency of the cooler and the dispersion plate or causes the back of the temperature probe. To shut down the reactor.

Another problem arises mainly in catalyst systems using high activity catalysts, and relates to sheet generation in the reactor. Since metallocene catalysts are highly active, they generate very high local heat in polymers grown in polymerization. This local heat forms a molten sheet, which, when stuck to the reactor wall, leads to a state in which normal reaction operation is not possible.

Many studies have been conducted to improve the problems caused when using such a highly active supported metallocene catalyst. For example, US Pat. No. 5,283,218 discloses a method for directly injecting a prepolymer of a metallocene catalyst into a reactor, and US Pat. No. 5,332,706 discloses a method for injecting and using a carrier simultaneously with the formation of a carrier. It is.

In addition, an improved method with respect to process stability when applying a metallocene catalyst is disclosed in US Pat. No. 5,627,243, which discloses a method of inhibiting sheet formation by injecting an inert hydrocarbon into the reactor. .

Although these methods reduce the formation of agglomerates and sheet formation to some extent, there are disadvantages in that the use of a supported metallocene catalyst does not sufficiently reduce the formation of agglomeration and sheet formation in a commercial continuous gas phase polymerization process.

International patent WO 97/46599 discloses a method in which an unsupported metallocene catalyst is dissolved and injected into a solvent and an antistatic agent, in particular ATMER 163 (a mixture of tertiary fatty acid amines), is injected into the solution stream.

EP 0 811 638 discloses a method of using a catalyst and a promoter in a nitrogen stream containing an antistatic agent. In this embodiment, a method of dispersing a catalyst supported on mineral oil and injecting the catalyst into the reactor is provided. According to this method, it is possible to obtain a dispersing effect in the reactor fluidized bed by using a continuous injection method rather than discontinuously injecting a high active catalyst, and to reduce local heat generation. However, the catalyst simply dispersed in oil may be deposited in the catalyst vessel before injection into the polymerization reactor, which requires continuous agitation, which causes the particles of the catalyst to break up to form fine powders, thereby making it impossible to maintain a stable reaction. There is a disadvantage.

It is an object of the present invention to increase the effect of dispersion by diluting and dispersing a highly active catalyst, unlike the conventional method of periodically injecting an excessive amount of catalyst, and to prevent the rapid rise of the initial reaction heat by inhibiting the access of the monomer to the active site, It is to provide a polyolefin gas phase polymerization method for preventing fouling and sheet formation.

In the polyolefin gas phase polymerization method of the present invention, the supported metallocene catalyst system is mixed with a dispersant and then injected into a gas phase fluidized bed reactor through a double annular nozzle, wherein the dispersant is a mixture of mineral oil and grease, and the mineral oil is a dispersant. Characterized in that present at 60 to 90% by weight of the total weight.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

Metallocene catalyst

Although the metallocene catalyst used for the polyolefin gas-phase polymerization method of this invention does not have a restriction | limiting in particular in the kind, What has a structure represented by following General formula (I) as a preferable example is mentioned.

(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 ligands of metallocene catalysts used in the present 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, such 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, halogen, and the like. 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:

Me ₂ Si (THI) ₂ ZrCl ₂ ,

Et (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, 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 metallocene catalyst component may be prepared and used in a suitable carrier. Preferred carriers are solid particulate porous, preferably inorganic materials, for example oxides of silicon and / or aluminum. Most preferably, the carrier is silica present in the form of spherical particles, for example spherical particles obtained by a spray drying method, in particular the surface area is preferably from 100 to 1,000 m 2 / g, more preferably from 200 to 700 m 2. Preferred is a silica carrier having a / g, pore volume of 0.54 ml / g, more preferably 0.5 to 3 ml / g.

The process for preparing the metallocene supported catalyst is carried out by reacting a mixed solution of metallocene and methylaluminoxane with a carrier as described above. The content of methylaluminoxane and metallocene which are commonly used in the preparation of a solid carrier catalyst is very wide. The molar ratio of transition metal in aluminum to metallocene is preferably 1: 1 to 600: 1, and 100 : 1 to 300: 1 are more preferable. The supported reaction temperature is preferably -20 to 200 ° C, more preferably 40 ° C to 160 ° C, and most preferably 80 ° C to 120 ° C. 30 minutes-4 hours are preferable, and, as for reaction time, 1 hour-2 hours are more preferable.

The loading is carried out under stirring. By contact with the OH group and the methylaluminoxane solution of silica, methylaluminoxane is supported on the silica, and the metallocene catalyst component is supported on the methylaluminoxane. According to this reaction, the methylaluminoxane liberated in the formed catalyst does not exist. The supported catalyst is characterized by very high supporting efficiency of transition metals and aluminum. The supported catalyst thus prepared is washed with a hydrocarbon solvent. Preferably, washing twice, preferably using an aromatic solvent for the first wash, and aliphatic solvent for the second wash. In the first washing step, unreacted metallocene and unsupported methylaluminoxane are removed. In the present invention, the first washing temperature is preferably -40 ° C to 120 ° C, more preferably -20 ° C to 60 ° C, most preferably 10 ° C to 30 ° C, and the second washing temperature is not particularly limited. It is preferable that it is normal temperature (about 25 degreeC).

Injection of catalyst

In the polyolefin polymerization process according to the invention, the injection of the catalyst into the reactor preferably takes place continuously in the form of dispersion in mineral oil / grease mixture as a dispersant. The content of mineral oil in the mineral oil / grease mixture is 60 to 90% by weight, preferably 70 to 80% by weight. If the content of the mineral oil is less than 60% by weight, the viscosity is too high, making it difficult to inject, and the monomer is difficult to access the catalyst particles, resulting in a problem of lowering the reaction. A problem arises in which the catalyst precipitates within.

The content of the catalyst dispersed in the mineral oil / grease mixture is 5-20% by weight of the total weight of the mineral oil / grease mixture and the catalyst as a dispersant, preferably 8-15% by weight. When the content of the catalyst is less than 5% by weight, the amount of the catalyst is small, so that olefin polymerization is not easily performed. When the content of the catalyst is more than 20% by weight, the dispersion effect of the catalyst is reduced to form fouling or sheets. Problem occurs.

Referring to FIG. 1, the supported metallocene catalyst dispersed in mineral oil / grease is passed through a nozzle inserted into the polymerization reactor 2 continuously from the catalyst storage vessel 6 by a syringe pump 5. Is injected. The mineral oil / grease prevents the supported metallocene catalyst from sedimenting while in the syringe pump vessel and from sedimenting through the injection tube between the syringe pump 5 and the polymerization reactor 2.

The mineral oil / grease separates each of the catalyst particles from each other, thus preventing the monomers from approaching the active site after the catalyst has been injected into the fluidized bed and dispersed, thereby allowing the initial reaction to proceed slowly, eventually generating local heat. It serves to suppress the.

In the polyolefin polymerization method according to the present invention, the injection of the catalyst through the catalyst stream 9 and the injection of the transfer medium through the transfer medium stream 7 are made through an annular double nozzle 12 as shown in FIG. The inner nozzle 11 of the annular double nozzle 12 is supplied with a supported metallocene catalyst dispersed in mineral oil / grease, and the outer nozzle 10 is a conveying medium for assisting the dispersion of the catalyst in the reactor 2. The feed medium to the external nozzle is preferably an inert gas or a reaction recycle gas.

The size of the outer nozzle 10 and the inner nozzle 11 is an area ratio of the inner nozzle 11: the outer nozzle 10 is 1: 2 to 1: 3, preferably 1: 2.3 to 1: 2.7. When the ratio of the area is less than 1: 2, the amount of the catalyst is greater than that of the transport medium to be injected, so that the catalyst is not dispersed properly. When the ratio of the area exceeds 1: 3, the fluidized bed itself to which the catalyst is to be dispersed is There is a problem of being removed by the dispersion medium.

The flow rate of the transfer medium is preferably 400 to 3000 times the catalyst flow rate, and more preferably 800 to 1500 times. If the flow rate of the transfer medium is less than 400 times the catalyst flow rate, the mineral oil / grease dispersion catalyst may accumulate at the nozzle inlet and may not be dispersed in the fluidized bed. If the flow rate exceeds 3000 times the catalyst flow rate, The problem arises in that the fluidized bed in which the catalyst has to be dispersed is removed.

In the polyolefin polymerization method according to the present invention, the inner nozzle 11 of the annular double nozzle, into which the catalyst is injected, is preferably eccentrically biased upward. This eccentricity prevents the catalyst flow from being disturbed by the fluidized bed in the reactor 2 at the nozzle end, thereby preventing the nozzle from clogging.

The inner nozzle 11 into which the catalyst is injected is joined with the auxiliary transport medium stream 8 at the nozzle end to increase the injection speed, and is converted into a discontinuous state to produce a preliminary dispersion effect.

In the polyolefin polymerization method according to the present invention, as the transfer medium flowing into the catalyst injection device, an olefin or a copolymerization monomer which is a reaction monomer or nitrogen or an inert hydrocarbon which is an inert gas may be used. Preferably, nitrogen which is an inert gas is used.

Polymerization of Polyolefins

In the present invention, the polyolefin is a gas phase reaction of a gas phase polymerization composition comprising hydrogen, an olefin and a comonomer, if necessary, in the presence of a metallocene catalyst (carrier) to be injected as the main catalyst. Are prepared.

In the method for producing a polyolefin according to the present invention, the metallocene supported catalyst is preferably combined with one or more activators to form a polymerization catalyst system. Preferred activators used in this case include alkylaluminum compounds (e.g. diethylaluminum chloride), aluminoxanes, modified aluminoxanes, neutral or ionic ionizing activators, noncoordinating anions, noncoordinating group 13 metal or metalloid anions, boranes And borate salts.

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.

The alkyl aluminum compound is in accordance with the desired polymer properties

100≤transition metal in alkylaluminum compound / metallocene catalyst≤1000

It is preferable to use during gas phase polymerization at molar ratio of

300 ≤ transition metal in an alkylaluminum compound / metallocene catalyst ≤ 500

It is more preferable to use at the time of gas phase polymerization in the molar ratio of.

If the molar ratio of the transition metal in the alkylaluminum compound / metallocene catalyst is less than 100, sufficient polymerization activity cannot be obtained, whereas if it exceeds 1000, the polymerization activity is lowered.

Use of aluminoxanes or modified aluminoxanes as activators and / or neutral or ionic ionizing activators to ionize neutral metallocene compounds, such as tri (n-butyl) ammonium tetrakis (pentafluorophenyl) boron or tris The use of perfluorophenylboron metalloid precursors is also within the scope of the present invention. Other compounds useful as activators include triphenylboron, triethylboron, tri-n-butylammonium tetraethylborate, triarylborane and the like. Aluminate salts are also useful compounds.

In the method for producing polyolefin according to the present invention, the hydrogen contained in the composition for gas phase polymerization is used to adjust the molecular weight of the resulting polymer, and the content ratio of hydrogen and olefin is 0.0005 in a hydrogen / olefin molar ratio. It is -0.002, Preferably it is 0.008-0.0015. If the hydrogen / olefin molar ratio is less than 0.0005 or more than 0.005, the molecular weight of the polymer is too low or too high, making application to the product difficult.

In the method for producing polyolefin according to the present invention, ethylene is preferably used as the olefin included in the composition for gas phase polymerization, and in this case, the comonomer optionally used is propylene, 1-butene, 1-hexene, 4 Alpha-olefins other than ethylene, such as -methyl-1-pentene and the like, are preferable, and the content ratio of the comonomer to the ethylene is 0.001 to 0.05 in the molar ratio of comonomer / ethylene, preferably 0.005 to 0.03. If this comonomer / ethylene molar ratio is less than 0.001 or greater than 0.05, the desired level of copolymer cannot be obtained. This is because, if the content of the comonomer in the gas phase polymerization composition is too small, the crystal size is partially increased in the copolymer during processing, thereby decreasing the transparency, whereas, if the content of the comonomer is too high, the softening point of the copolymer This is because the softening temperature is lowered, which reduces the reaction stability in the gas phase polymerization reactor.

In the process for producing polyolefin according to the present invention, the polymerization reaction is carried out in the absence of a hydrocarbon solvent, preferably 60 to 120 ° C, more preferably 65 to 100 ° C, even more preferably 70 to 80 ° C, and preferably Preferably it is carried out by gas phase polymerization at a pressure of 2 to 40 atmospheres, more preferably 10 to 30 atmospheres.

If the polymerization temperature in the gas phase fluidized bed reactor is less than 60 ° C, sufficient polymerization efficiency cannot be obtained, and if it exceeds 120 ° C, there is a problem that a polymer mass is easily generated. In addition, when the operating pressure in the gas phase fluidized bed reactor is less than 2 atm, the heat capacity per unit volume is too low to obtain a sufficient polymerization efficiency, when exceeding 40 atm becomes difficult to control the reaction, and imposes a force on the reactor.

According to the polyolefin polymerization method of the present invention, a uniform catalyst dispersion is prepared by using a viscosity-controlled mineral oil / grease dispersant when injecting a supported high active metallocene catalyst into a gas phase polymerization reactor, and using the annular double nozzle By continuously injecting it through, it is possible to prevent local heat generation and to suppress sheet generation and fouling. This is because by diluting and dispersing the highly active catalyst, the effect of dispersion is enhanced as compared with the method of periodically injecting an excessive amount of catalyst, and the initial reaction heat is prevented from rising rapidly by inhibiting access to the active point of the monomer.

In addition, in the polyolefin polymerization method of the present invention, an annular double catalyst injection nozzle is used to induce effective dispersion into the fluidized bed, and catalyst particles accumulate at the end of the nozzle to prevent polymerization from clogging the catalyst injection tube. have.

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

Preparation of Supported Metallocene Catalyst

The metallocene catalyst component, Et (THI) ₂ ZrCl _2, is described in W. Spalek; A. Antberg, J. Rohrmann, A. Winter, B. Bachmann, P. Kiprof, J. Behm, and WA Hermann, Angew. Chem. Int. Eng. Ed. 1992, 31, 1347] was used.

The carrier used XPO-2402 (APS 50 micro, surface area 300 m ² / g, micropore volume 1.6 cc / g, OH concentration 1 mmol / g) dehydrated silica. 5 g of the silica was suspended in toluene in a round bottom flask equipped with a magnetic stirrer, a nitrogen inlet and a dropping funnel.

In order to produce an activated catalyst, 0.3 g of the metallocene catalyst Et (THI) ₂ ZrCl ₂ was reacted with 25 ml of methylaluminoxane (30% by weight of MAO in toluene) for 10 minutes to provide a corresponding metallocene cation and A solution of the anionic methylaluminoacid oligomer was calculated.

The solution containing the resulting metallocene cation and anionic methylaluminoxane oligomer was immediately replaced by a reflux condenser under nitrogen and then added dropwise to the suspended silica. The mixtures were each heated to 110 ° C. for 90 minutes. The reaction mixture was then cooled to room temperature, filtered under nitrogen and washed with toluene.

Thereafter, the obtained catalyst system was washed with pentane and then dried under mild vacuum.

Preparation of Mineral Oil / Grease Mixtures as Dispersants

Mineral oil was used as Kaidol white oil (Witco). This oil has a viscosity at 40 ° C. of 64 to 70 cst, a specific gravity of 0.8732, and a molecular weight of 405 g / mol.

Grease used Witco's White Protopet 1S, which had a viscosity of 10 to 16 sct at 100 ° C, a specific gravity of 0.838, and a freezing point of 54.7 ° C. Both the mineral oil and the grease were subjected to nitrogen bubbling at 200 ° C. to adjust the residual moisture to 1 ppm or less.

At room temperature, mineral oil is in solution, but grease is below its freezing point, so it is solid. To evenly disperse the two materials, grease and oil were mixed in a weight ratio of 20:80 and stirred at 60 ° C. to prepare a uniform solution.

Preparation of mineral oil / grease mixture with dispersed catalyst

10 g of the supported metallocene catalyst prepared by the above method was quantified, and then added to 90 g of a homogeneous mineral oil / grease mixture solution, followed by stirring to achieve even dispersion. All this was done under nitrogen atmosphere to prevent catalyst deactivation. The catalyst (hereinafter, 'catalyst / dispersant mixture') dispersed in the mineral oil / grease prepared as described above was not precipitated even after standing for 5 days or more at room temperature.

Vapor polymerization in fluidized bed

The polymerization process was carried out in the polymerization reaction equipment of FIG. The fluidized bed consists of polymer particles. A gaseous feed stream of ethylene and hydrogen and monomers were introduced into the recycle gas line below 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 chromatograph such that the composition of the recycle gas stream was relatively constant.

The supported metallocene catalyst dispersed in the oil grease mixture prepared above was injected into the polymerization reactor 2 using the syringe pump 5 of FIG. 1. In the injection, the injection nozzle was injected in the direction of the catalyst flow 9 through the inner nozzle 11 using the annular double nozzle shown in FIG. 2. Purified nitrogen was injected into the fluidized bed along with the catalyst through the external nozzle 10 of the double nozzle of FIG. As another catalyst transfer medium, the recycle gas flow of the polymerization reaction was introduced in the direction of the transfer medium stream 7 of the catalyst injection in FIG. 2, and the flow rate was 1000 times the catalyst injection rate. The injection rate of the catalyst was adjusted to maintain a constant production rate. The reaction bed, consisting of growing polymer particles, remains fluidized by the continuous flow of monomer supplements and recycle gas through the reaction zone. 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. The product was discharged by the continuous operation by a series of valves. The exiting polymer is freed of unreacted monomer in the degassing vessel and loses activity as it passes through the steamer.

The polymerization process was performed for 6 days under the polymerization conditions shown in Table 1 below.

TABLE 1

Reaction condition value Temperature (℃) 80 Pressure (kg / ㎠) 19.2 Ethylene (mol%) 30 Hydrogen (mol%) 0.03 Hydrogen / ethylene (molar ratio) 0.001 1-hexene (mol%) 0.39 1-hexene / ethylene (molar ratio) 0.013 Bed weight (kg) 90 Retention time (hr) 14 Gas flow rate (cm / sec) 15.6 Output speed (kg / hr) 6.5 Apparent density (g / cc) 0.48

Comparative Example 1

The gas phase polymerization reaction was carried out under the same conditions as in Example, except that the supported metallocene catalyst was mixed with a dispersant consisting of only the mineral oil.

Comparative Example 2

A gas phase polymerization reaction was carried out under the same conditions as in Example, except that the catalyst / dispersant mixture was injected using a single nozzle as shown in FIG. 3.

Comparative Example 3

As shown in FIG. 4, except that the inner nozzle 11 'is not eccentric, and the catalyst / dispersant mixture is injected using the converted double nozzle 12' having the same center position as the outer nozzle 10 '. Then, gas phase polymerization reaction was carried out under the same conditions as in Example.

Table 2 shows the results of the operation period, fouling and clogging of the internal nozzles of Examples and Comparative Examples 1 to 3.

TABLE 2

Driving period Fouling Internal nozzle blockage Example 6 days none none Comparative Example 1 2 days has exist catch Comparative Example 2 3 days has exist catch Comparative Example 3 3 days none catch

As shown in Table 2, fouling occurred in Comparative Examples 1 and 2, and internal nozzles were clogged in both Comparative Examples 1 to 3, so that the operating period of Comparative Examples was not the same as 6 days. , 2 days, 3 days and 3 days, respectively. In addition, as shown in Table 2, in Comparative Example 1, when dispersed only in the oil does not inhibit the initial overreaction, causing fouling in the reactor, the viscosity is low, the clogging of the injection tube due to sedimentation problem in the catalyst injection line Occurred.

In Comparative Example 2, since the conveying medium did not flow around the catalyst injection nozzle, the oil grease dispersion catalyst liquid injected into the fluidized bed did not uniformly disperse in the fluidized bed, causing fouling in the reactor.

In Comparative Example 3, catalyst dispersion in the fluidized bed was normally performed due to the flow of the transfer medium to the double pipe to prevent fouling in the reactor, but clogging at the end of the catalyst injection pipe occurred.

1 is a schematic diagram of a polymerization reaction plant of the present invention.

2 is a schematic diagram of the catalyst injection of the present invention.

3 is a schematic view of catalyst injection in Comparative Example 2. FIG.

4 is a schematic view of catalyst injection in Comparative Example 3. FIG.

<Code description>

2 polymerization reactor

5 syringe pump

6 catalyst storage containers

7 Transport medium flow

8 Transport medium flow

9 catalyst flow

10, 10 'external nozzle

11, 11 'internal nozzle

12, 12 'annular dual nozzle

13 toroidal single nozzle

Claims (5)

In the method of gas phase polymerization of polyolefin, a supported metallocene catalyst system is mixed with a dispersant and then injected into a gas phase fluidized bed polymerization reactor through an annular double nozzle, and the dispersant is a mixture of mineral oil and grease, 60 to 90% by weight of the total weight of the dispersant, wherein the annular double nozzle comprises an inner nozzle and an outer nozzle, the inner nozzle is eccentric in the upper direction, characterized in that the polyolefin gas phase polymerization method. The method of claim 1, wherein the weight ratio of the catalyst mixed in the dispersant is 5 to 20% by weight of the total weight of the dispersant and the catalyst. The polyolefin gas phase polymerization method according to claim 1, wherein the ratio of the area of the inner nozzle to the outer nozzle in the annular double nozzle is 1: 2 to 1: 3. The polyolefin gas phase polymerization method according to claim 1, wherein the inner nozzle of the annular double nozzle is a catalyst injection nozzle, and the outer nozzle is a transfer medium injection nozzle selected from one of an inert gas and a reaction recycle gas. The polyolefin gas phase polymerization method according to claim 4, wherein the flow rate of the transfer medium injected through the outer nozzle is 400 to 3000 times the flow rate of the catalyst injected through the inner nozzle.

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