JPH0436166B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for polymerizing olefins using specific titanium catalysts. More specifically, the present invention relates to a method for polymerizing olefins that does not cause troubles in the process due to coarse particles. Various methods have been used to increase the yield of polyolefin per catalyst since the invention of the Ziegler-Natsuta catalyst.
The method proposed in No. 12105 using a catalyst obtained by supporting titanium halide on a metal halide and an organoaluminum compound is effective. In addition, many improvements have been proposed regarding this method, and catalyst performance has improved significantly over the past decade, with catalysts boasting high performance of tens of thousands of grams per titanium catalyst/g titanium catalyst being reported. . When olefin is polymerized in a homogeneous solution state, the solution viscosity becomes extremely high, and the removal of polymerization heat becomes difficult.
Since it is difficult to transfer the solution, polymerization is generally carried out in a slurry state in a liquid or gas phase medium. In this slurry polymerization, the polyolefin is present in the form of particles, but it is preferable that the particles are not huge or fine. In particular, if there are large particles, there is a problem that they can accumulate in narrow parts of equipment such as polymerization tanks and piping, and in some cases become clogged. This clogging problem is a serious problem in a continuous production method such as olefin polymerization, which can lead to the entire platoon being stopped. The present inventors conducted various studies to solve the above problem, and as a result, they discovered that this problem could be solved by using a titanium catalyst with special consideration given to the shape, and completed the present invention. An object of the present invention is to provide a method for polymerizing olefins that is free from troubles caused by coarse polyolefin particles. That is, the method for polymerizing olefin of the present invention involves combining a titanium catalyst obtained by supporting titanium tetrachloride on a carrier obtained by co-pulverizing a magnesium halide and an organic compound containing a C-O bond, and an organoaluminum compound. In the method of polymerizing olefin using a catalyst consisting of, after passing a titanium catalyst in a slurry state in an inert hydrocarbon medium through a mesh sieve with a mesh opening smaller than R expressed by the following formula [1]. The present invention relates to a method for polymerizing olefin, which is characterized in that it is used. Formula [1]: In the formula, R ₀ is the critical slurry particle size of the process, d ₁ is the density of the polyolefin, d ₂ is the density of the titanium catalyst, and W represents the amount of polyolefin produced per titanium catalyst. Magnesium halides used in the present invention include magnesium chloride, magnesium bromide, and the like, with magnesium chloride being preferred. Further, as the organic compound, various known compounds used in producing a magnesium halide carrier can be used, but in the present invention, C-O bond-containing compounds are preferably used. Various known methods can be employed as the co-pulverization method, but co-pulverization using a ball mill or a vibration mill is particularly preferred. The support thus obtained is then brought into contact with liquid titanium halide to produce a titanium catalyst. In the present invention, titanium tetrachloride, which is liquid itself, is preferably used as the titanium halide, but it is also possible to use it diluted with a hydrocarbon or the like. The contact is carried out in close contact using an appropriate stirring means, usually under heating above room temperature, preferably at 40 to
It is best to do this at 135℃. Many conditions for these contact conditions are already known. In the present invention, the titanium catalyst obtained by the above treatment is passed in a slurry state in an inert hydrocarbon medium through a mesh sieve having a mesh opening smaller than R in the formula [1]. The inert hydrocarbon medium used in the present invention includes aliphatic hydrocarbons such as hexane, heptane, and decane, aromatic hydrocarbons such as benzene, toluene, and xylene, or mixtures thereof. The process limit slurry particle size of R ₀ in formula [1] indicates the minimum diameter of coarse particles when the various process troubles described above occur due to the presence of coarse particles. In other words, when a certain trouble occurs, it is the minimum diameter of the coarse particles that are the cause. This depends on the details of the process and cannot be specified, but if the polymerization is carried out in a liquid medium slurry, no particles larger than 10 mm should be present. Preferably, there should be no particles larger than 5 mm. In addition, in the gas phase medium slurry method, the allowable particle size of coarse particles is generally large, but it is still better not to have particles larger than 10 mm. Preferably R ₀ is less than or equal to 5 mm. Passage through the mesh sieve may be performed while applying appropriate vibrations so that the material passes under the action of gravity, but as this increases the amount of titanium catalyst that does not pass through, a method of forcibly passing it with a brush or spatula may be adopted. Alternatively, the slurry may be passed under pressure using an autoclave. The titanium catalyst thus obtained is combined with an organoaluminum compound and subjected to the polymerization of olefin.The organoaluminum compounds used in the present invention include trialkylaluminum, dialkylaluminum chloride, alkylaluminum sesquichloride, alkylaluminum dichloride, and other commercially available organoaluminum compounds. Examples include various organoaluminum compounds available at The olefin used in the present invention includes ethylene,
Examples include propylene, butene-1, hexene-1, etc., and their homopolymerization or mutual copolymerization is carried out, but the effect is particularly great in α-olefins having 3 or more carbon atoms such as propylene and butene-1. . That is, the polymerization method of the present invention does not cause any deterioration in catalyst performance, particularly the stereoregularity of the obtained polyolefin. The method of the present invention makes it possible to produce polyolefin in high yield per catalyst without any trouble caused by coarse particles, and is therefore extremely valuable industrially. EXAMPLES The present invention will be explained in more detail with reference to Examples below. [Example, Comparative Example] Predicted value of R The critical slurry particle size for the propylene polymerization process was set to the normal value of 5 mm, the density of the titanium catalyst determined in advance (actual value 2.2) and the density of polypropylene 0.9, and The normal value of W in this catalyst system, approximately 20,000, was substituted into the above equations to obtain an approximate value of R. Using this R value as a standard, the method of the present invention is carried out using a mesh sieve with a smaller opening (wire mesh with an opening of 0.147 mm) and a mesh sieve with a larger opening (wire mesh with an opening of 0.295 mm). carried out. Example 1, Comparative Example 1 A. Production of titanium catalyst 30 g of magnesium chloride containing 0.4 wt% water,
4.5 ml of ethyl orthoacetate and 3 ml of 1,2-dichloroethane were placed in a 600 ml grinding pot containing 80 stainless steel balls with a diameter of 12 mm, and ground for 40 hours. Next, 30 g of the co-pulverized product was placed in a 500 ml round bottom flask, 150 ml of titanium tetrachloride was added, and the mixture was stirred at 80°C for 1 hour.The solid portion was then washed 5 times with 300 ml of n-heptane, and further n-heptane was extracted. After adding 150 ml of titanium tetrachloride, the mixture was stirred at 80°C for 1 hour. The solid portion was then poured into 300 ml of n-
Wash with heptane 7 times and add 150ml of n-heptane.
was added to form a titanium catalyst slurry. Half of the amount was used as it was in the polymerization reaction (Comparative Example 1), and half of the amount was passed through a wire mesh with an opening of 0.147 mm and used in the polymerization reaction (Example 1). The slurry was passed through the wire mesh by putting the slurry in a pressure-resistant container with a wire mesh at the bottom, pressurizing it, and passing the slurry almost quantitatively. (b) Polymerization reaction Prepare an autoclave with an internal volume of 5 that has been thoroughly dried and purged with nitrogen. Pour 50 ml of dried n-heptane into a 200 ml flask that has been thoroughly dried and purged with nitrogen. Add diethylaluminum chloride.
0.128 ml, methyl toluate 0.06 ml, and triethylaluminum 0.08 ml were added, and the mixed catalyst slurry was put into the above autoclave. Next, 1.5 kg of propylene and 0.6 N of hydrogen were added, and the autoclave was heated to bring the internal temperature to After polymerizing at 75℃ for 2 hours, unreacted propylene was discharged and the resulting polypropylene powder was taken out and heated at 60℃.
The procedure of weighing after drying for 10 hours is performed as described in b) above.
The experiment was carried out using two types of titanium catalysts obtained in . The intrinsic viscosity (hereinafter abbreviated as η, measured in a tetralin solution at 135°C) of the powder obtained in each case is boiling n-
Heptane extraction residual rate (hereinafter abbreviated as II) extracted with boiling n-heptane in a Soxhlet extractor for 6 hours and calculated as extraction residual polymer weight / polymer weight before extraction × 100%), bulk specific gravity and particle size distribution (Tyler Mess., USA) The measured results are shown in the table. Eye opening as shown in the table
It can be seen that in the example using the titanium catalyst slurry passed through a 0.147 mm wire mesh, there were no coarse polyolefin particles with an opening of 4.7 mm or more (ASTM standard sieve #4). Example 2, Comparative Example 2 A titanium catalyst slurry was synthesized in the same manner as in Example 1, except that the additives during co-pulverization were changed to 6 ml of cumene and 3 ml of 1,2-dichloroethane, and half of the slurry was made using a 0.295 mm wire mesh (Comparative Example 2) Also, half of the amount is 0.147mm wire mesh (Example 2)
The procedure was the same as in Example 1 except that . 0.295
It can be seen that there are coarse polyolefin particles of 4.7 mm or more when treated with a wire mesh of 4.7 mm. Comparative Example 3 The same procedure as Comparative Example 1 was carried out except that a glass stirrer chip was placed in the catalyst slurry of Comparative Example 1 and the slurry was vigorously stirred for 2 hours using a stirrer. The results are shown in the table. 【table】

[Brief explanation of drawings]

FIG. 1 is a flowchart to aid understanding of the present invention.

Claims (1)

[Claims] 1. Using a catalyst consisting of a titanium catalyst obtained by supporting titanium tetrachloride on a carrier obtained by co-pulverizing magnesium halide and an organic compound containing a C-O bond and an organoaluminum compound. In the method for polymerizing olefin, the titanium catalyst is used in a slurry state in an inert hydrocarbon medium after being passed through a mesh sieve having a mesh opening smaller than R expressed by the following formula. Olefin polymerization method: Formula: In the formula, R ₀ is the critical slurry particle size of the process, d ₁ is the density of the polyolefin, d ₂ is the density of the titanium catalyst, and W represents the amount of polyolefin produced per titanium catalyst. 2. The method for polymerizing olefin according to claim 1, wherein the olefin is an α-olefin having 3 or more carbon atoms.