JPH0320403B2 - - Google Patents

Description

[Detailed description of the invention]

In the present invention, in the presence of a catalyst formed from a reduction metal compound catalyst component and an organometallic compound catalyst component,
The present invention relates to an improvement in a method for polymerizing olefins in which olefins are continuously polymerized in multiple stages in at least two separate polymerization zones connected in series. In particular, the present invention provides a liquid medium exchange zone between an upstream polymerization zone and a subsequent downstream polymerization zone, which are connected to both zones, and separately supplies a liquid medium to the lower part of the exchange zone. By making it possible to exchange the dispersion medium introduced from the upstream slurry polymerization zone with the separately supplied liquid medium, it is possible to remove the insufficiently grown fine powder polymer, catalyst, and molecular weight adjustment in the slurry. A portion consisting mainly of the dispersion medium from the upstream polymerization zone containing agents and the like is circulated to the upstream polymerization zone, while a solid polymer portion mainly consisting of the grown polymer is preferentially placed below the exchange zone. It is possible to supply a flow consisting mainly of the grown solid polymer in the separately supplied liquid medium to the downstream polymerization zone, so that the setting of the polymerization conditions in the downstream polymerization zone is similar to that of the upstream polymerization. Problems that are unfavorably affected by polymerization conditions in the zone, problems with polymer uniformity and quality fluctuations, etc. can be advantageously avoided, and the above problems in continuous multi-stage polymerization of olefins can be avoided with simple addition means and easy operation. Concerning improvement methods that can be overcome. More particularly, the present invention provides continuous multistage polymerization of olefins in at least two serially connected separate polymerization zones in the presence of a catalyst formed from a reduction metal compound catalyst component and an organometallic compound catalyst component. (i) conducting the polymerization in the upstream polymerization zone under slurry polymerization conditions; (ii) introducing the solid polymer-containing slurry discharged from the upstream polymerization zone into the upstream polymerization zone and the polymerization zone; The liquid medium is supplied to the upper supply port provided at the top of the liquid medium exchange zone connected between the downstream polymerization zone, and the liquid medium is separately supplied to the exchange zone from the lower supply port provided at the bottom of the exchange zone. and (iii) circulating an exhaust stream from an upper outlet provided at the upper part of the exchange zone to the upstream polymerization zone and a lower outlet provided at the lower part of the exchange zone. The present invention relates to a method for polymerizing olefins, characterized in that a discharge stream is supplied to the downstream polymerization zone. In the present invention, the term "polymerization of olefins" is sometimes used to include not only homopolymerization of olefins but also copolymerization of olefins, and similarly, the term "polymer" is used to include not only homopolymerization of olefins but also copolymerization of olefins. It is sometimes used to include copolymers. In order to continuously produce olefin polymers having various molecular weight distributions and/or composition distributions, olefin polymerization is carried out sequentially using two or more separate polymerization zones connected in series with different polymerization conditions. There have already been many proposals regarding so-called continuous multi-stage polymerization of olefins. When polymerization is carried out in the form of a slurry in the upstream polymerization zone in such continuous multi-stage polymerization, the polymer-containing slurry discharged from the zone is usually flushed, partially concentrated, or directly sent to the downstream side. is supplied to the polymerization zone to continue polymerization. In this case, unreacted olefins used in the upstream polymerization zone, molecular weight modifiers such as hydrogen, polymerization catalyst components such as organoaluminum compound catalyst components and electron donor catalyst components are entrained in the feed stream to the downstream polymerization zone. This affects the polymerization in the downstream polymerization zone, and as a result, it is often difficult to set the polymerization conditions in the downstream polymerization zone. Furthermore, in continuous multi-stage polymerization in a tank-type polymerizer using a Ziegler-type catalyst, a residence time distribution occurs in the residence time of each catalyst particle, so it is not possible to obtain sufficiently satisfactory results in terms of polymer uniformity and quality. It is often not possible. The present inventors have continued their research in order to provide an improvement method that can advantageously overcome the above-mentioned troubles in continuous multi-stage polymerization of olefins. As a result, (i) the polymerization in the upstream polymerization zone is conducted under slurry polymerization conditions, and (ii) the solid polymer-containing slurry discharged from the upstream polymerization zone is transferred to the upstream polymerization zone and the subsequent downstream polymerization zone. The liquid medium is supplied to the upper supply port provided at the upper part of the liquid medium exchange zone connected between the polymerization zone and the liquid medium is separately supplied to the exchange zone from the lower supply port provided at the lower part of the exchange zone. and (iii) circulating the discharge stream from the upper outlet provided at the upper part of the exchange zone to the upstream polymerization zone, and circulating the discharge stream from the lower outlet provided at the lower part of the exchange zone. It has been found that by feeding the downstream polymerization zone, the above-mentioned troubles can be advantageously overcome by simple means and operations. According to the research of the present inventors, the above (i), (ii) and (iii)
By carrying out the continuous multi-stage polymerization of olefin under conditions that satisfy the requirements of the present invention, a sufficiently grown solid polymer is preferentially lowered in the liquid medium exchange zone, so that the solid polymer can be dispersed. It has been found that it is possible to replace the dispersion medium in the upstream polymerization zone with a liquid medium newly supplied mainly from below the exchange zone. As a result, the dispersion medium discharged from the upstream polymerization zone is preferentially returned to the upstream polymerization zone, while the downstream polymerization zone is supplied with the liquid medium separately supplied in the liquid medium exchange zone. It has been found that the solid polymer can be delivered with a liquid medium that mainly consists of a liquid medium that differs from the upstream liquid composition. In this way, there is an advantage that the polymerization conditions in the downstream polymerization zone can be set without being influenced by the effects of olefin, hydrogen, catalyst components, etc. on the upstream side, making it easy to design the quality of the polymer. Ta. Furthermore, since the fine particles in the polymer from the upstream polymerization zone settle more slowly than the grown particles, they can be returned to the polymerization zone along with the circulating flow from the upper outlet of the liquid medium exchange zone. . Many of these fine powder parts are generated by the shot pass of the catalyst, impairing the uniformity of product quality, but since they can be cut out with this method, it is possible to improve the particle size distribution and quality of the product. It turns out that the catalyst can also be used efficiently. Furthermore, it has been found that if the polymerization in the downstream polymerization zone is carried out in the gas phase, this also results in improved fluidity. Therefore, an object of the present invention is to provide an improved method for the continuous multi-stage polymerization of olefins, which can advantageously overcome the problems of the conventional methods. The above objects and many other objects and advantages of the present invention will become more apparent from the following description. The reduction metal compound catalyst component used in carrying out the method of the present invention is a compound of reduction metal such as titanium, vanadium, chromium, zirconium, etc., and may be liquid or solid under the conditions of use. It's okay. 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 composite compound with other compounds. A preferred component (A), as described above, is about 1 mmol of reduced metal.
Highly active reduction metal catalyst components capable of producing olefin polymers of 5,000 g or more, particularly about 8,000 g or more, and a highly active titanium catalyst component activated by a magnesium compound is exemplified as a representative example. can do. For example, a solid titanium catalyst component containing titanium, magnesium, and 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 can be exemplified by a component of about 80 to about 800 m ² /g. and contains electron donors such as organic acid esters, silicate esters, acid halides, acid anhydrides, ketones, acid amides, tertiary amines, inorganic acid esters, phosphate esters, phosphites, ethers, etc. Good too. This catalyst component contains, for example, about 0.5 to 15% by weight of titanium, in particular about 1 to about 8% by weight, with a titanium/magnesium (atomic ratio) of about 1/2.
or about 1/100, especially about 1/3 to about 1/50, halogen/titanium (atomic ratio) about 4 to about 100,
Particularly preferred are those in which the electron donor/titanium (molar ratio) is in the range of from about 6 to about 80, and from 0 to about 10, particularly from 0 to about 6. Many of these catalyst components have already been proposed and are widely known. In addition, the organometallic compound catalyst component, which is the other component constituting the catalyst, is an organometallic compound of a metal from Group 1 to Group 3 of the periodic table and a carbon bond, and specific examples thereof include: Examples include organic compounds of alkali metals, organic metal compounds of alkaline earth metals, and organic aluminum compounds. Specific examples of these include alkyl lithium, aryl sodium, alkyl magnesium, aryl magnesium, alkyl magnesium halide, aryl magnesium halide, alkyl magnesium hydride, trialkyl aluminum, dialkyl aluminum monohalide, alkyl aluminum sesquihalide, alkyl aluminum dihalide, Examples include alkyl aluminum hydride, alkyl aluminum alkoxide, alkyl lithium aluminum, and mixtures thereof. In addition to the two components of the catalyst, for the purpose of adjusting stereoregularity, molecular weight, molecular weight distribution, etc., electron donor catalyst components such as organic acid esters, silicate esters, alkoxysilanes, carboxylic acid halides,
Carboxylic acid amides, tertiary amines, acid anhydrides, ethers, ketones, aldehydes, etc. or halogenated hydrocarbons may also be used. During polymerization, the electron donor catalyst component may be used after forming a complex compound (or addition compound) with the organometallic compound catalyst component in advance, or may be used in combination with other compounds such as Lewis acids such as aluminum trihalides. It may be used in the form of a complex compound (or addition compound) with. Examples of olefins used in polymerization include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene,
4-methyl-1-pentene, 3-methyl-1-pentene, styrene, butadiene, isoprene,
1,4-hexadiene, dicyclopentadiene,
Examples include 5-ethylidene-2-norbornene. According to the method of the invention, the polymerization in the upstream polymerization zone is carried out under slurry polymerization conditions. The liquid medium (dispersion medium) used in the upstream slurry polymerization zone may be the olefin itself to be polymerized, or may be an inert hydrocarbon. Examples of inert hydrocarbons include propane, butane, pentane, isopentane, hexane, heptane, octane, decane, kerosene, and the like. When the polymerization in the downstream polymerization zone is carried out under gas phase conditions, in the above examples, olefins having about 3 to 5 carbon atoms and/or
Alternatively, the polymerization is preferably carried out in a liquid medium selected from inert hydrocarbons. During polymerization, hydrogen may be present in order to adjust the molecular weight. Especially when performing the same olefin polymerization in the downstream polymerization zone as in the upstream polymerization zone,
It is advantageous from the viewpoint of catalytic activity to produce a polymer with a small molecular weight in the upstream polymerization zone. The polymerization temperature varies depending on the type of olefin to be polymerized, but it must be within a range where slurry polymerization is possible, for example, below the melting point of the olefin polymer, preferably at least 10°C lower than the melting point, and from room temperature to about
The temperature is about 130°C, especially about 40°C to about 110°C. In addition, the polymerization pressure is, for example, atmospheric pressure to about 150
Kg/cm ² , preferably in the range of about 2 to about 70 Kg/cm ² . In the case of using a reduced metal compound catalyst component, an organometallic compound catalyst component, an electron donor catalyst component, etc. as described above, the reduced metal compound catalyst component is converted into reduced metal atoms per one liquid medium. 0.0005 to about 1 mmol, especially about 0.001 to about 0.5 mmol, of the organometallic compound catalyst component in an amount of the metal/reduced metal (atomic ratio) of about 1 to about 2000, especially about 1
It is preferable to use a proportion of from about 500 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. Slurry polymerization is conducted substantially continuously. That is, each catalyst component, raw material olefin, hydrogen, and in some cases an inert solvent are continuously supplied to the upstream polymerization zone. These components are supplied fresh and/or as a recycle stream from the exchange zone. Each catalyst component may be dissolved or suspended in an inert solvent and separately supplied to the polymerization zone, or it may be preliminarily prepared in the presence or absence of a small amount of olefin before being supplied to the polymerization zone. You may leave them in contact. Although various known devices can be used as the polymerization zone, the most typical device is a tank-type polymerization device with a stirrer, which can be suitably used in the present invention. The slurry concentration in the upstream polymerization zone is approximately 50
Preferably, the solid polymer-containing slurry is substantially continuously withdrawn from the polymerization zone and fed to an upper feed port provided at the top of the liquid medium exchange zone. In the exchange zone, such a slurry comes into contact with a liquid medium separately supplied from a lower supply port provided at the lower part of the exchange zone, and a device having a shape that allows the solid polymer to easily move downward is provided. do it. At this time, it is preferable that the liquid medium constituting the solid polymer-containing slurry supplied from the upstream polymerization zone is left as much as possible in the upper part of the liquid medium exchange zone, discharged from the upper discharge port, and circulated to the upstream polymerization zone. Therefore, it is preferable to use a device such as a piston flow type liquid-liquid exchange contactor or a hydrocyclone. The liquid medium supplied to the lower part of the liquid medium exchange zone includes liquid olefins and/or inert hydrocarbons, preferably those having 3 or more carbon atoms, as exemplified as the liquid medium in the upstream slurry polymerization zone.
10 things. And preferably they are selected among the olefins or diluents (vehicles) used in the downstream polymerization zone. In order to sufficiently prevent undesirable components such as finely powdered polymer from moving from the upstream polymerization zone to the downstream polymerization zone, the amount of liquid medium supplied here must be adjusted from the outlet at the bottom of the exchange zone to the downstream polymerization zone. Preferably, the amount is at least equal to the amount of polymer-containing liquid discharged into the zone. As such a solvent, it is also possible to use an olefin or the like vaporized by the heat of polymerization in the upstream polymerization zone and liquefied by cooling. When the polymerization in the downstream polymerization zone is carried out in the gas phase, the heat of polymerization can be removed by vaporizing the discharged liquid, so the amount of discharged liquid can be adjusted for this purpose. In this way, it is possible to prevent unnecessary components present in the upstream polymerization zone from being brought into the downstream polymerization zone in excess of the required amount to the polymer supplied from the liquid medium exchange zone to the downstream polymerization zone. It is possible to set conditions in the downstream polymerization zone without being influenced by polymerization conditions in the upstream polymerization zone. Polymerization in the downstream polymerization zone can be carried out in a slurry or gas phase. In particular, when performing gas phase polymerization, by adopting the present invention,
Since the finely powdered polymer is cut, it is also effective in improving fluidity and preventing clogging of the exhaust gas system. Furthermore, as described above, polymerization heat control can be easily performed by adjusting the amount of liquid to be introduced. When performing gas phase polymerization in the downstream polymerization zone, a method is adopted in which the polymer slurry from the liquid medium exchange zone is directly supplied to the gas phase polymerization zone, where the liquid medium is vaporized and polymerized. Of course, part or all of the liquid medium can be vaporized before being supplied to the downstream polymerization zone, or it can be concentrated in advance. A new catalyst component may be added to the downstream polymerization zone, but since the catalyst contained in the solid polymer formed in the upstream polymerization zone is present, no new catalyst component is added. Sufficient polymerization activity was observed in both cases. When the polymerization in the downstream polymerization zone is carried out in the form of a slurry, it can be carried out under the same conditions as described for the polymerization in the upstream polymerization zone. In addition, when polymerization in the downstream polymerization zone is carried out in the gas phase, there are no other methods than conducting the polymerization under conditions that allow gas phase polymerization using a known gas phase polymerization device such as a fluidized bed, a stirred fluidized bed, or a stirred bed. , conditions similar to those described for slurry polymerization can be employed. In the downstream polymerization zone, a polymer having a different molecular weight and composition from the polymer in the upstream polymerization zone can be produced. Another polymerization zone may be provided upstream of the above-mentioned upstream polymerization zone or downstream of the downstream polymerization zone. As an example of a preferred embodiment of the present invention, a crystalline propylene or ethylene polymer is produced by slurry polymerization in an upstream polymerization zone, and a propylene or ethylene polymer having a different molecular weight or composition is produced in a downstream polymerization zone. An example is a method of producing by phase polymerization. In this case, a step of polymerizing propylene or ethylene in a gas phase may be provided further downstream. According to the present invention, a polymer having desired physical properties can be easily produced. FIG. 1 is a drawing showing one embodiment of the present invention. A catalyst is continuously supplied to the first polymerization tank 11 through a tube 1, and an olefin is continuously supplied through a tube 2, respectively. A polymerization slurry in which the polymer is suspended in liquid olefin is withdrawn from tube 3 and fed to the top of a countercurrent contactor 12 forming a liquid medium exchange zone. A liquid olefin is separately supplied as a fresh liquid medium through a pipe 4 below the countercurrent contactor 12 . The liquid withdrawn from above the countercurrent contactor is circulated through the pipe 5 to the first polymerization tank 11 . On the other hand, the slurry extracted from below the countercurrent contactor is transferred from the pipe 6 to the second polymerization tank 13.
to continue polymerization. The polymer extracted from the second polymerization tank is discharged from the polymerization system through a pipe 7. Example 1 In FIG. 1, a catalyst formed from a titanium catalyst component in which titanium tetrachloride and diisobutyl phthalate are supported on magnesium chloride, triethylaluminum and ethyl silicate is introduced from tube 1, and 1 weight of propylene is added per unit time. Hydrogen was sent from tube 2 to the first polymerization tank 1 so that the proportion of hydrogen and the composition of the gas phase was 3.5%, and at 30Kg/cm ² and 70℃,
Continuous slurry polymerization was carried out under conditions of an average residence time of 1 hour. The polymer slurry drawn out from tube 3 consisted of 1 part by weight of polypropylene and 2 parts by weight of propylene with an MI of 30° per unit time.
Propylene was supplied from pipe 4 at a rate of 2 parts by weight per unit time, and 2 parts by weight of propylene per unit time was circulated to the first polymerization tank from pipe 5. 1 part by weight of polypropylene and 2 parts by weight of propylene are extracted per unit time from the pipe 6 and led to the second polymerization tank 13, where they are subjected to gas phase polymerization under the conditions of 17 kg/cm ² and an average residence time of 1.5 hours at 80°C. was held.
As a result, polypropylene with MI4.5 and Mw/Mn=8.0 was obtained at a rate of 1.7 parts by weight per unit time. 0.7% by weight of polypropylene with a particle size of 200μ or less
It was nothing more than a simple thing. To aid understanding, [Table 1] shows the mass balance of propylene and polypropylene.

[Table] Example 2 In FIG. 1, a titanium catalyst component in which titanium tetrachloride and diisobutyl phthalate are supported on magnesium chloride, a catalyst formed from triethylammonium and ethyl silicate is introduced from tube 1, and the composition of the gas phase is Hydrogen was sent from tube 2 to the first polymerization tank 1 at a concentration of 3.5 mol%, and circulating propylene from tube 5, which will be described later, was fed at 30 kg/cm ² at 70°C.
Continuous slurry polymerization was carried out under conditions of an average residence time of 1 hour. A polymer slurry containing 1 part by weight of MI=30 polypropylene and 1 part by weight of propylene is extracted from pipe 3 per unit time, propylene is supplied from pipe 4 at a rate of 2 parts by weight per unit time, and propylene is supplied from pipe 5. 2 parts by weight per unit time was circulated to the first polymerization tank. 1 part by weight of polypropylene and 1 part by weight of propylene were extracted per unit time from the tube 6 and led to the second polymerization tank 13, where they were subjected to gas phase polymerization under the conditions of 17 kg/cm ² and an average residence time of 1.5 hours at 80°C. . As a result, MI=4.0,
Mw/Mn=8.4 polypropylene per unit time
It was obtained in a proportion of 1.7 parts by weight. The amount of fine powder polymer with a particle size of 200μ or less was only 0.4% by weight. Table 2 shows the material balance.

[Table] Comparative Example 1 In FIG. 1, a catalyst formed from a titanium catalyst component in which titanium tetrachloride and diisobutyl phthalate were supported on magnesium chloride, triethylaluminum and ethyl silicate was fed from tube 1, and per unit time. 3 parts by weight of propylene and 3.5 mol% of hydrogen in the composition of the gas phase were sent from tube 2 to the first polymerization tank 1, under the conditions of 30 kg/cm ² , 70°C, and an average residence time of 1 hour. Continuous slurry polymerization was performed. The polymer slurry drawn out from tube 3 consisted of 1 part by weight of polypropylene of MI=30 and 2 parts by weight of propylene per unit time. In this comparative example, propylene was not supplied from tube 4 and circulated to the first polymerization reactor through tube 5, but the slurry was simply passed through the countercurrent contactor. 1 part by weight of polypropylene and 2 parts by weight of propylene were extracted per unit time from the tube 6 and led to the second polymerization tank 13, where they were subjected to gas phase polymerization under the conditions of 17 kg/cm ² and an average residence time of 1.5 hours at 80°C. . As a result, MI=5.5,
Polypropylene with Mw/Mn=7.2 per unit time
It was obtained in a proportion of 1.8 parts by weight. Polypropylene with a particle size of 200 μm or less was 2.1% by weight. [Table 3] shows the material balance.

【table】 [Brief explanation of the drawing]

The attached FIG. 1 is a process diagram showing one embodiment of the present invention.

Claims (1)

[Scope of Claims] 1. Continuous multistage polymerization of olefins in at least two series-connected separate polymerization zones in the presence of a catalyst formed from a reduction metal compound catalyst component and an organometallic compound catalyst component. The method includes: (i) conducting the polymerization in an upstream polymerization zone under slurry polymerization conditions; (ii) transferring a solid polymer-containing slurry discharged from the upstream polymerization zone to the upstream polymerization zone and the subsequent polymerization zone; The liquid medium is supplied to the upper supply port provided at the top of the liquid medium exchange zone connected between the downstream side polymerization zone, and the liquid medium is separately supplied to the exchange zone from the lower supply port provided at the bottom of the exchange zone. (iii) circulating a discharge stream from an upper outlet located at the upper part of the exchange zone to the upstream polymerization zone and a discharge stream from a lower outlet located at the lower part of the exchange zone; A method for polymerizing olefins, characterized in that a flow is supplied to the downstream polymerization zone.