JPS6243441B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improved method for continuous gas phase polymerization of olefins using a mixed type polymerization vessel, and is an improvement that enables production of polymers with good physical properties having significantly improved particle properties and homogeneity in high yield. The present invention relates to a continuous gas phase polymerization method for olefins. More specifically, the present invention involves the continuous gas phase polymerization of olefins using a mixed type polymerization vessel, by applying a high-speed gas flow to the polymer discharged from the polymerization vessel to remove fine powder in the polymer. The present invention relates to a method for the gas phase polymerization of olefins, characterized in that a polymer component is entrained in the gas stream and circulated through the polymerization vessel. In the present invention, the term "polymerization" 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. When carrying out the gas phase polymerization, there are many proposals to use a complete mixing type polymerization vessel, such as a fluidized bed type polymerization vessel, a stirred fluidized bed type polymerization vessel, or a stirred bed type polymerization vessel, in order to proceed with the polymerization smoothly. However, when performing continuous gas phase polymerization of olefins using such a mixed polymerization vessel,
It is extremely difficult in practice to maintain a constant residence time of the catalyst, and it is difficult to avoid a distribution of residence times of the catalyst in the reaction zone. As a result, in addition to the disadvantage that some of the catalyst is not used effectively and is discharged from the polymerization reactor,
The particle size of the formed polymer also becomes irregular,
The presence of inconvenient fine powder polymer components and poor powder fluidity cause problems in that it is difficult to smoothly transport and process the obtained polymer. The present inventors conducted research to overcome the above-mentioned troubles and disadvantages that occur when performing continuous gas phase polymerization of olefins using a mixed type polymerization reactor. As a result, under simple operating conditions, a high-speed gas flow is applied to the polymer discharged from the polymerization vessel, and the finely powdered polymer components in the polymer are entrained in the gas flow and circulated to the polymerization vessel. By carrying out continuous gas phase polymerization, it is possible to achieve improvements in the properties of polymer powder, such as a reduction in fine powder, an increase in bulk density, and an improvement in particle fluidity.As a result, the transfer of the resulting polymer, Handling and processing can be carried out smoothly and easily, and the obtained polymer powder can be used for painting, painting, etc.
It has been discovered that it has excellent suitability as a powder grade for use in rotary molding, press molding, or mixing with fillers. Furthermore, by adopting the above-mentioned circulation method, it is possible to achieve the unexpected improvement effect of improving the polymer yield per unit transition metal catalyst, and also to obtain a polymer with good homogeneity, especially in multi-stage continuous production. We have discovered that by employing gas phase polymerization, these effects become even more pronounced and it becomes possible to produce polymers with excellent physical properties. Accordingly, it is an object of the present invention to provide an improved process 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. In the continuous gas phase polymerization 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. The preferred transition metal compound catalyst component is about 5,000 g or more, particularly about 8,000 g/mmol of transition metal.
A titanium catalyst component that is highly activated with a magnesium compound is a typical example of a highly active component that can produce an olefin polymer of 1.5 g or more. 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. The catalyst component may include, for example, about 0.5 to about 10% by weight of titanium;
In particular, it contains about 1 to about 8% by weight, titanium/magnesium (atomic ratio) is about 1/2 to about 1/100, especially about 1/3 to about 1/50, and halogen/titanium (atomic ratio) is about 4. from about 100 to about 100, especially from about 6 to about
80, electron donor/titanium (molar ratio) is 0 to about
10, particularly preferably in the range of 0 to about 6. Many of these catalyst components have already been proposed and are widely known. The organometallic compound catalyst component is an organic compound having a bond between a metal of Groups 1 to 3 of the periodic table and carbon, and specific examples include organic compounds of alkali metals and organic metals of alkaline earth metals. compounds, organoaluminum compounds, etc., such as alkyl lithium, aryl sodium,
Alkylmagnesium, arylmagnesium,
Examples include alkylmagnesium halide, arylmagnesium halide, alkylmagnesium hydride, trialkyl aluminum, alkyl aluminum halide, alkyl aluminum hydride, alkyl aluminum alkoxide, alkyl lithium aluminum, and mixtures thereof. 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 acid amides, Tertiary amines, acid anhydrides, ethers, ketones, aldehydes, etc. may be used in combination.
This electron donor component is preliminarily formed into a complex compound (or addition compound) with an organometallic compound catalyst component during polymerization.
It may be used after forming a complex compound (or addition compound) with another compound such as a Lewis acid such as aluminum trihalide. In the method of the present invention, examples of olefins used in polymerization include ethylene, propylene, 1-
Butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 4-methyl-1-pentene,
Examples include 3-methyl-1-pentene, styrene, butadiene, isoprene, 1,4-hexadiene, dicyclopentadiene, and 5-ethylidene-2-norbornene. Polymerization can be carried out. The method of the present invention can be preferably used for homopolymerization of ethylene or propylene, copolymerization of ethylene and other olefins, and copolymerization of propylene and other olefins. Gas phase polymerization can be carried out using a mixed type polymerization vessel such as a fluidized bed polymerization vessel, a stirred bed polymerization vessel, a stirred fluidized bed polymerization vessel, and the like. The reaction temperature is 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. The polymerization pressure is, for example, atmospheric pressure to about 150 kg/cm ² , particularly 2 to about 150 kg/cm 2 .
A range of 70 Kg/cm ² is preferred. Hydrogen optionally used in the polymerization is preferably used in an amount of, for example, about 0.001 to about 20 mol, particularly about 0.02 to about 10 mol, per 1 mol of olefin. 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 amount of the transition metal compound catalyst component is about 0.0005 to 0.0005 to 1,000,000 in terms of transition metal atoms per 1 volume of the reaction bed. about 1 mmol, especially about 0.001 to about 0.5
millimoles of the organometallic compound catalyst component to the metal/
It is preferable to use the transition metal (atomic ratio) in a proportion of about 1 to about 2000, particularly about 1 to about 500. In addition, the electron donor catalyst component is added in an amount of 0 to about 1 mol per 1 mol of the organometallic compound catalyst component.
In particular, it is preferable to use it in a proportion of about 0 to about 0.5 mol. Olefin polymerization is carried out substantially continuously (including short periodic intermittent operations). That is, a catalyst, an olefin, hydrogen, a diluent, etc., if necessary, are continuously supplied to a polymerization vessel, and polymerization is performed in a solid-gas mixed state based on rising gas, mechanical stirring, and the like. The polymer is continuously taken out from the polymerization vessel, and at this time, the gas inside the polymerization vessel is also entrained. In the method of the present invention, a high-speed gas flow is applied to such a polymer discharged from a polymerization vessel, and the finely powdered polymer components in the polymer are entrained in the gas flow and circulated to the polymerization vessel. At this time, it is preferable to preferentially entrain the fine powder component (fine powder polymer component) with the gas stream with as small a gas amount as possible and with good classification effect. For example, the polymer taken out from the polymerization vessel is taken out into a vertical container with a diameter smaller than the diameter of the polymerization vessel, for example, about 1/14 to about 1/5 of the diameter of the polymerization vessel, and the polymer is poured into a container from below. It is preferable to blow the gas at a speed of about 40 to about 1000 cm/sec, extract it from above as a gas stream containing fine powder components, and return it to the polymerization vessel. The amount of the component of the finely divided polymer to be recycled is preferably about 0.1 to about 50% by weight, particularly about 1 to about 20% by weight of the polymer discharged from the polymerization vessel. Powdered polymer with large particle size that is not entrained by the high-velocity gas is extracted from the bottom of the vertical container and made into a product with or without post-processing, or in the case of multi-stage polymerization, it is transferred to the next polymerization step. sent to. It is preferable that such operations are also performed continuously. As an accompanying gas component used for the above purpose,
For example, olefin used in polymerization or a mixture of olefin and hydrogen can be used. for example,
In polymerization vessels, a method is often adopted in which unreacted gas discharged from the polymerization vessel is cooled to remove polymerization heat and then circulated to the polymerization vessel, but such circulating gas may also be used for the above purpose. . However, if a large amount of olefin is brought into contact with a catalyst-containing polymer in a part other than the polymerization vessel, polymerization may proceed at a non-negligible rate.
It is preferable to use an inert gas such as propane or butane, or a mixed gas containing a large proportion of these inert gases. Another advantage of using the above-mentioned inert gas is that it facilitates the subsequent handling of large particle polymer particles, and especially when multi-stage polymerization is employed, the gas composition of the previous polymerization vessel remains the same even when sent to the next polymerization vessel. Being able to drive without being affected. The gas stream containing the pulverulent polymer component can be circulated to any location in the polymerization vessel, but it prevents polymerization in undesired locations in the polymerization vessel and entrainment of the pulverulent polymer component within the polymerization vessel. For this reason, it is preferable to circulate it directly to the polymerization zone in the polymerization vessel. In addition, when introducing into the upper space of the polymerization zone, it is preferable to supply it as close to the polymerization zone as possible and to spray it onto the polymerization zone. According to the present invention, it is possible to improve polymerization activity, modify polymers, and improve operability. Next, an example will be explained. Comparative Example 1 [Catalyst synthesis] Put 4.8 g of MgCl ₂ , 15 ml of decane and 18 ml of 2-ethylhexanol into a 200 ml flask, and heat at 120°C.
After performing a heating reaction for 2 hours to obtain a homogeneous solution, 0.84 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 0°C, the entire amount of the homogeneous solution was added dropwise over 1 hour, and then the temperature was raised to 80°C. 2 at 80℃
After stirring for an hour, 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 has Ti4.8wt% and Cl59wt
%, Mg 18wt%, average particle diameter 4.0μ, and specific surface area 248m ² /g. [Catalyst pretreatment] After drying the obtained titanium catalyst component and suspending it in propane (0.5 mmol Ti/), triisobutylaluminum (500 mmol/) and 3 g of propylene per 1 g of the titanium catalyst component were added. was supplied and pretreated at 40°C. Next, 0.5 m of the above catalyst was placed in a tubular reactor with an inner diameter of 30 cm and a length of 200 cm, equipped with a stirrer.
mol Ti/hr, triisobutylaluminum 5m
mol Ti/hr, propane 15/hr, ethylene 45g/hr, 1-hexene 15g/hr, temperature 50℃, pressure 17
Prepolymerization was carried out continuously at Kg/cm ² ·G to produce 100 g of polymer with a density of 0.920 g/cc per 1 mmol of Ti. [Polymerization] The above prepolymerization catalyst was flashed and then supplied to a fluidized bed reactor with a diameter of 300 mm and a reaction volume of 30 mm, and propane, ethylene, 1-hexene,
Hydrogen was supplied. Furthermore, the gas discharged from the upper part of the reaction bed was cooled to 60°C in a cooler and then circulated to the lower part of the reactor. Reaction temperature was 80℃, reaction pressure was 10Kg/cm ² G, superficial gas velocity was 30cm/sec, 1-hexene/ethylene (molar ratio) = 0.1, propane/ethylene (molar ratio) =
3.5, polymerization was carried out under the conditions of hydrogen/ethylene (molar ratio) = 0.4, and in order to keep the height of the reaction bed almost constant, the polymer was extracted intermittently, and the density was 0.930.
g/cc, MI0.95, bulk density 0.43g/cc, average particle size
Ethylene polymer of 350μ was obtained at 10Kg/hr. Examples 1 to 3 In the polymerization method of Comparative Example 1, the extracted polymer was introduced into a fluidized bed type device with a diameter of 10 cm and a capacity of 2,
Gases shown in Table 1 were introduced from below. The gas containing the fine powder polymer component discharged from the top was circulated to the reactor, and a polymer with large particle size was obtained from the bottom. The polymerization results are shown in Table 1.

【table】

【table】

Claims (1)

[Claims] 1. When carrying out continuous gas phase polymerization of olefins using a mixed type polymerization vessel, a high-speed gas flow is applied to the polymer discharged from the polymerization vessel to remove the fine powder in the polymer. A method for the gas phase polymerization of olefins, characterized in that a polymer component is entrained in the gas stream and circulated through the polymerization vessel. 2. The amount of the finely divided polymer component that is recycled is about 0.1 to about 50% by weight of the polymer discharged from the polymerization vessel.
The gas phase polymerization method according to claim 1.