JPS6243444B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to the interface between a fluidized bed polymerization reaction zone and a gas phase zone above it, the so-called "fluidized bed interface", and the adhesion of produced polymer to the inner wall of a polymerization vessel in the vicinity thereof, as well as the prevention of lumps. Formation troubles can be industrially advantageously avoided, and the contact state of each component of the polymerization system, such as the catalyst, polymer particles, and gaseous olefin, is uniform and good.
The present invention relates to an improved method for the gas phase polymerization of olefins, which can produce polymers with good compositional distribution, molecular weight distribution, particle shape, etc. using stable polymerization operations. In addition, in the present invention, the term “polymerization” refers to
The term "polymer" is sometimes used to include not only homopolymerization but also copolymerization, and the term "polymer" is sometimes used to include not only homopolymers but also copolymers.

As a result of improvements in transition metal catalyst components for olefin polymerization, the production capacity of olefin polymers per unit transition metal has been dramatically increased, and as a result, we have reached a stage where the catalyst removal operation after polymerization can be omitted.
When using such a highly active catalyst, a method of carrying out olefin polymerization in the gas phase is attracting attention because it is the simplest to operate after polymerization.

In the gas phase polymerization, in order to proceed smoothly with the polymerization, a tower-type polymerizer such as a tower-type fluidized bed polymerizer or a tower-type stirred fluidized bed polymerizer is used, and the catalyst is catalyzed by an upward flow of olefin-containing gas. A fluidized bed polymerization method has been widely used, in which polymerization is carried out while the olefin polymer contained therein is suspended and fluidized, and the polymer in the exhaust gas is collected as needed and circulated in the polymerization zone. When using such a fluidized bed, it is recommended to form a stable fluidized region for polymerization.
To this end, the rate of rise of the olefin-containing gas must be approximately 1.5 times to less than 10 times the minimum fluidization rate;
In particular, it is said that it should be increased by about 2 to about 6 times (for example, Japanese Patent Application Laid-open No. 139983/1983).

However, the factors governing the state of the fluidized bed are not only the above-mentioned speed, but also the shape of the polymerization vessel, the dispersion plate, the height of the fluidized bed, and other factors. In cases where the fluidity state in the polymerization zone is not necessarily satisfactory, or even when the fluidity state is good, the catalyst introduction is not uniform or the polymer particle shape is not good, stabilized polymerization must be carried out. For example, the formation of lumps and the adhesion of polymers to walls are likely to occur. Such undesired phenomena are particularly likely to occur at and near the fluidized bed interface.

The present inventors have conducted research in order to avoid the above-mentioned disadvantages that often occur at fluidized bed interfaces, and to develop a means to perform stable gas phase polymerization with industrially easy operations. I went.

As a result, we have adopted a high gas flow rate, which has not been considered in conventional column-type polymerizers, and we have introduced the exhaust gas into a cyclone to collect the polymer entrained in the gas. By carrying out the gas phase polymerization of olefins under conditions that satisfy the combined requirement of some or all circulation in the polymerization zone, a number of improvements, contrary to those expected from previous proposals, have been achieved. I discovered a surprising fact that it can be achieved.

According to the research conducted by the present inventors, by carrying out a gas phase polymerization reaction of olefins under conditions that satisfy the above bonding requirements, various components of the polymerization system such as catalytic agents, polymer particles, and gaseous olefins can be separated. It was found that the contact condition was very uniform and good, and as a result, it was easy to produce a polymer with a narrow composition distribution and molecular weight distribution. Furthermore, with the conventional technology, a noticeable improvement effect can be obtained on the wall surface portion or directly above the dispersion plate, where movement was slow, and the above-mentioned adhesion of the produced polymer to the inner wall of the polymerization vessel and formation of lumps in the polymerization vessel can be reduced. The problem was resolved, and even powder with poor fluidity showed more active movement than expected, confirming that safe operation could be carried out over a long period of time. Unexpectedly, it has been found that the negative effects such as equipment wear and polymer particle breakage are negligible in practice.

Accordingly, it is an object of the present invention to provide an improved method for the gas phase polymerization of olefins.

The above objects and many other objects and advantages of the present invention will become more apparent from the following description.

According to the present invention, polymerization is carried out in a column-type polymerization vessel while floating and fluidizing the olefin polymer by an upward flow of the olefin-containing gas, and if desired, the polymer in the exhaust gas is collected at any time. In a fluidized bed gas phase polymerization method for olefins in which the gas is circulated to the polymerization zone, (i) the rate of gas rise in the column is higher than 10 times the minimum fluidization rate, and (ii) the gas is discharged from the top of the column. A method for polymerizing olefins is provided, which comprises introducing gas into a cyclone to collect entrained polymer, and circulating part or all of the collected polymer to a polymerization vessel.

In the gas phase polymerization method of the present invention, it is preferable to use a catalyst formed from a transition metal catalyst component and an organometallic compound catalyst component of a metal from Group 1 to Group 3 of the Periodic Table.

The transition metal compound catalyst component is a compound of a transition metal such as titanium, vanadium, chromium, zirconium, etc., and may be liquid or solid under the conditions of use. These do not need to be a single compound, and may be supported on other compounds or mixed. Furthermore, it may be a complex compound or a composite compound with other compounds.

Suitable transition metal compound catalyst components include transition metal 1
A titanium catalyst component highly activated by a magnesium compound is exemplified as a representative example of a highly active component capable of producing about 5,000 g or more, particularly about 8,000 g or more of olefin polymer per mmol. Can be done. For example, titanium,
A solid titanium catalyst component containing magnesium and a halogen as essential components, containing amorphous magnesium halide, and having a specific surface area of preferably about 40 m ² /g or more, particularly preferably about 80 m 2 /g or more. 800 m ² /g can be exemplified. and electron donors such as organic acid esters, silicate esters, acid halides, acid anhydrides,
It may contain ketones, acid amides, tertiary amines, inorganic acid esters, phosphate esters, phosphite esters, ethers, and the like. This highly active catalyst component contains, for example, about 0.5 to about 10% by weight of titanium, especially about 1 to about 8% by weight, and the titanium/magnesium (atomic ratio) is about 1/2 to about 1/100, especially about 1/3 to about 1/50, halogen/titanium (atomic ratio) about 4 to about 100, especially about 6 to about 80, electron donor/titanium (molar ratio) 0 to about 10, especially 0 to about 6 Preferably, it is within this range. Many of these catalyst components have already been proposed and are widely known, and can be preferably used in the method of the present invention.

The organometallic compound catalyst component is an organometallic compound having a bond between a metal of Groups 1 to 3 of the periodic table and carbon, and specific examples include organometallic compounds of alkali metals and alkaline earth metals. Examples include organometallic compounds and organoaluminum compounds. Such organometallic catalyst components include:
For example, alkyl lithium, aryl sodium, alkyl magnesium, aryl magnesium, alkyl magnesium halide, aryl magnesium halide, alkyl magnesium hydride, trialkyl aluminum, alkyl aluminum halide, alkyl aluminum hydride, alkyl aluminum alkoxide, alkyl lithium aluminum, mixtures thereof, etc. can be exemplified.

In addition to the above two components, for the purpose of adjusting stereoregularity, molecular weight, molecular weight distribution, etc., hydrogen, halogenated hydrocarbons, electron donor catalyst components, such as organic acid esters, silicate esters, carboxylic acid halides, carboxylic acids amides, tertiary amines, acid anhydrides,
Ethers, ketones, aldehydes, etc. may be used in combination. The electron donor component may be used after forming a complex compound (or addition compound) with the organometallic compound catalyst component in advance during polymerization, or may be used after forming a complex compound (or addition compound) with the organometallic compound catalyst component. Compounds and complex compounds (or addition compounds)
It may be used in a formed form.

In the method of the present invention, the olefins used for polymerization include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 4-methyl-1-pentene, 3
Examples include C2 to _C12 olefins and dienes such as -methyl-1-pentene, styrene, butadiene, isoprene, 1,4-hexadiene, dicyclopentadiene, and 5-ethylidene- ₂ -norbornene, and gas phase polymerization These homopolymerizations and copolymerizations can be carried out to the extent possible.

The method of the present invention is preferably used for homopolymerization of ethylene or propylene, copolymerization of ethylene with other olefins and/or dienes, and copolymerization of propylene with other olefins and/or dienes. can.

Gas phase polymerization can be carried out using a tower type polymerizer that is generally used as a fluidized bed polymerizer.
The reaction temperature is preferably below the melting point of the olefin polymer, preferably about 10°C or more lower than the melting point, and from room temperature to about 130°C, particularly about 40 to about 110°C. Further, the polymerization pressure is, for example, atmospheric pressure to about 150 Kg/cm ² , particularly about 2 to about 70 Kg/cm 2 .
A range of cm ² is preferred. Hydrogen that can be optionally used during polymerization is, for example, about 1 mole of olefin.
0.001 to about 20 moles, especially about 0.02 to about
It is preferable to use it in a range of 10 moles. Furthermore, in order to remove the heat of polymerization, a liquid easily volatile hydrocarbon such as propane or butane may be supplied and vaporized in the polymerization zone.

When using a transition metal compound catalyst component, an organometallic compound catalyst component, an electron donor catalyst component, etc. as described above, the polymerization zone volume is 1, and the transition metal compound catalyst component is approximately 0.0005 in terms of transition metal atoms.
from about 1 mmol, especially from about 0.001 to about
Preferably, 0.5 mmol of the organometallic compound catalyst component is used in a ratio such that the metal/transition metal (atomic ratio) is from about 1 to about 2000, especially from about 1 to about 500. Further, it is preferable to use the electron donor catalyst component in a proportion of 0 to about 1 mol, particularly 0 to about 0.5 mol, per 1 mol of the organometallic compound catalyst component.

Gas phase polymerization is carried out by blowing an olefin-containing gas into the lower part of the gas distribution plate of the tower type polymerization vessel, while causing the catalyst-containing polymer located above the gas distribution plate to float and flow. At this time, the rate of gas rise in the column is maintained to be higher than 10 times, preferably about 12 to about 50 times, the minimum fluidization rate. By employing such high gas flow rates, better contact between the components of the reaction system is achieved and, unlike in conventional fluidized bed polymerizations, more of the polymer is transported to the column with the exhaust gas stream. It will be pulled out from the top.

In the method of the present invention, in addition to employing a high gas flow rate as described above, the exhaust gas containing such polymers is guided to a cyclone to collect most of the polymer while removing the polymer. The exhaust gas can be appropriately passed through various devices such as a cooler and a blower, and then circulated to the polymerization zone for reuse.

A part or all of the polymer collected in the cyclone is circulated to the polymerization zone, but it must be moved quickly to prevent wall adhesion and circulation passage blockage due to excessive polymerization there. At this time, when part of the polymer is circulated, the remaining part can be extracted from the system and used, for example, as a product as it is. This method of taking out the product from the cyclone is preferable because the amount of gas entrained during removal is smaller than the method of taking out the product directly from the polymerization vessel in conventional polymerization using a fluidized bed. However, since removal of the product from the cyclone alone requires the entrainment of a significant amount of polymer, polymerization is It is preferable to use only the direct extraction method from the polymerization vessel, or a combination of the direct extraction method from the polymerization vessel and the extraction method of a part of the collected polymer using a cyclone.

Various methods can be employed to circulate the polymer collected in the cyclone to the polymerization vessel. Examples include a method in which a rotary valve is provided in the circulation path from the cyclone to the polymerization zone to allow the material to fall naturally, or a method in which the material is forcibly circulated to the polymerization vessel in order to prevent line blockage or adhesion on the line. A particularly suitable method is
Means include applying a high velocity gas flow across the lower part of the cyclone. Due to the ejector effect that occurs at this time, the polymer is suctioned away from the cyclone and is also sucked into the high-speed gas flow.
If this high-speed gas is supplied as it is to the gas phase polymerization zone, the desired polymer can be circulated.

Suction with high-speed gas may be performed continuously, but in order to control the amount of unreacted gas leaking into the high-speed gas flow, a rotary valve, timer valve, etc. should be installed between the lower part of the cyclone and the high-speed gas flow pipe. A valve mechanism may be provided to perform the operation intermittently. In any case, by forced suction removal, it is possible to shorten the residence time of the polymer in the cyclone, and it is possible to prevent problems such as wall adhesion and blockage.

The high-velocity gas used for the above-mentioned purpose, which serves both the polymer suction action and accompanying gas action, may be any gas that does not adversely affect the polymerization. For example, olefins used in polymerization, diluents, hydrogen, or mixtures thereof can be used.
The flow velocity of the high-speed gas may be as long as it exhibits a sufficient suction force at the communicating part with the lower part of the cyclone, for example, 1 m/m/m.
The speed may be approximately 100 m/sec to approximately 100 m/sec. If the pipe diameter of the communicating portion is appropriately reduced, there is no need to increase the amount of high-speed gas, so that the polymerization state will not be disturbed even if the gas is returned to the polymerization zone. As a method of returning the polymer to the polymerization zone, a method of directly supplying the polymer to the floating flow region, a method of spraying it into the region from above the region, etc. can be adopted.

FIG. 1 is a drawing showing one embodiment of the present invention. Catalyst is continuously supplied to the upper side of the column-type polymerizer 1 from the pipe 11, while olefin-containing gas consisting of circulating gas from the pipe 14 and fresh gas from the pipe 15 is fed to the lower part of the polymerizer 1 at high speed. Blow in. The olefin-containing gas passing through the perforated plate 8 causes the olefin polymer to float and flow while coming into contact with the contact to form a polymer. Gas components not involved in the reaction are discharged from the top of the polymerization vessel and led to a cyclone 2, where the entrained polymer is collected. The polymer collected in the cyclone is returned to the polymerization vessel through a rotary valve provided at the bottom of the cyclone. The gas components that have passed through the cyclone are transferred to cooler 4.
After cooling, the pressure is increased by a blower 5 and the polymer is circulated to the polymerization vessel 1. In order to keep the amount of polymer in the polymerization vessel approximately constant, it is continuously drawn out from tube 16 by means of valves 6 and 7.

Next, an example of polymerization using such an apparatus will be shown.

Example 1 [Catalyst synthesis] 7.2 g of anhydrous MgCl ₂ and 23 decane in a 200 ml flask
ml and 23 ml of 2-ethylhexanol,
A heating reaction was carried out at 120° C. for 2 hours to obtain a homogeneous solution, and then 1.68 ml of ethyl benzoate was added.

200 ml of TiCl ₄ was placed in a 400 ml flask, and while the flask was kept cooled at -20°C, the entire amount of the above homogeneous solution was added dropwise over 1 hour, and then the temperature was raised to 80°C. After stirring at 80°C for 2 hours, the solid portion was collected by filtration, suspended in 200 ml of fresh TiCl ₄ and stirred at 90°C for 2 hours. After the stirring was completed, the solid portion collected by heating was thoroughly washed with hot kerosene and hexane to obtain a titanium catalyst component. The catalyst contains Ti4.5wt% and Cl60wt
%, Mg 18wt%, average particle diameter 15μ, and specific surface area 195m ² /g.

[Catalyst pretreatment]

The obtained catalyst slurry was resuspended in hexane at a concentration of 5 mmol/calculated as Ti atoms, triethylaluminum was added at a concentration of 15 mmol/g, and propylene was further added at a concentration of 0.5 g per 1 g of titanium catalyst component. The treatment was carried out at 40°C.

[Polymerization]

In the polymerization apparatus shown in Fig. 1, a fluidized bed polymerization vessel with a diameter of 300 mm and a reaction section volume of 100 is used as a tower type polymerization vessel, and a Ti catalyst slurry readjusted to 0.5 mmol/-hexane in terms of Ti atoms is added to it with stirring. Triethylaluminum was fed at a rate of 1/hr from an equipped catalyst drum, and triethylaluminum was fed at a rate of 25 mmol/hr. On the other hand, when 1-butene and ethylene are mixed at a ratio of 1-butene/ethylene (mole ratio) = 0.07, the superficial gas velocity is 97 cm/sec (minimum fluidization velocity 8 cm/sec).
was supplied at a rate of The copolymer was extracted so that the amount of ethylene copolymer in the polymerization vessel was almost constant. The polymerization temperature was 90° C. and the polymerization pressure was 6 kg/cm ² G. Thus density 0.940g/cm ³ , melt index 1.3, bulk specific gravity 400Kg/m ³ , average particle size 600μ
of ethylene copolymer was obtained at a rate of 5.5 Kg/hr.
Even after 70 hours of continuous operation, there were no problems such as adhesion to walls.

[Brief explanation of the drawing]

FIG. 1 is a drawing showing one embodiment of the present invention.

Claims (1)

[Scope of Claims] 1. Polymerization is carried out in a column-type polymerization vessel while the olefin polymer is suspended and fluidized by an upward flow of olefin-containing gas, and the polymer in the exhaust gas is collected from time to time to the polymerization zone. In the fluidized bed gas phase polymerization method for onofine compounds, (i) the rate of gas rise in the column is made higher than 10 times the minimum fluidization rate, and (ii) the exhaust gas from the upper part of the column is transferred to a cyclone. 1. A method for gas phase polymerization of olefins, characterized in that the polymer introduced and entrained is collected, and part or all of the collected polymer is recycled to a polymerization zone.