JPS6361322B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for making Ziegler-type catalysts having rounded, dense particles with a relatively narrow size distribution and an average diameter of about 10 microns or more, preferably 20 microns or more. The catalyst of the present invention is particularly useful for polymerizing alpha-olefins to produce polyolefin powders. Stereospecific polymerization of alpha-olefins such as propylene is well known in the art. Polypropylene resin became the plastic that captured the global market. Sales of polypropylene powder are also currently increasing rapidly, even faster than sales of polypropylene pellets. The popularity of polypropylene powder is based, at least in part, on the rapidly increasing usage of filled polypropylene grades, particularly glass- or talc-filled grades. Most customers agree that polypropylene powder has all of the resin qualities normally found in pellet products, with good flow properties, low fines content and no "clumps" (large collections of particles). They also demand quality.
A suitably high bulk density is also desirable. It has been discovered that polymer powders consisting of rounded, compact particles with a relatively narrow size distribution possess these desirable physical properties. It was also discovered that since the catalyst particles provide a "template" for the production of polymer particles, the catalyst particles themselves must be rounded and dense with a relatively narrow size distribution. Ta. Furthermore, in order to obtain large powder particles, the catalyst particles themselves should be at least 10
They should have an average particle size of microns, preferably at least 20 microns and most preferably at least 35 microns. Conventionally, it has not been possible to simultaneously satisfy all of these objectives. Although it is possible to produce catalysts with rounded, compact particles in a narrow particle size range, the average particle diameter of the product is very small. Large particle catalysts can be produced, but this results in a loss of compactness.
Although it is possible to increase the average particle size by sieving the catalyst product to separate larger and smaller particles, this method has traditionally been unattractive because there is no use for the waste fines. Ta. The fines discharged according to the invention can be used as a "seed" for producing larger particles if desired. A method for producing particles that are small but have other desirable properties is disclosed in GB 1139450. In this patent a single step method is used in which TiCl ₄ is reduced in a well-mixed state.
TiCl ₄ and a reducing agent (e.g. diethyl aluminum chloride "DEAC") at low temperature (e.g. -40 °C to +15 °C)
Mix and gradually heat with stirring to a ripening temperature of 25°C to 45°C. When using DEAC,
The temperature must be below -5°C. Reagents are maintained at aging temperature for at least 2 hours. It has been discovered that relatively large particles can be obtained by using ethylaluminum dichloride (EADC) as a reducing agent. however,
The catalyst thus produced has a relatively high proportion of AlCl ₃ and has a lower activity compared to the catalyst produced by DEAC. The choice of reducing agent therefore depends on the requirements of the user. Of course, a mixture of DEAC and EADC can also be used, as can triethylaluminum (TEA). The present invention has relatively large particle diameters (e.g., particles with an average diameter of 10 to 200 microns, preferably 20 to 200 microns, and most preferably 35 to 50 microns) and a rounded particle size range of relatively narrow size. A method for producing a Ziegler-type catalyst consisting of dense particles is provided. The present invention uses a dispersion of finely divided ready-made catalyst as solid phase in the reduction zone during the reaction of TiCl ₄ (preferably with diethyl aluminum chloride) to produce the final product.
In this way, agglomeration of the catalyst fines as well as crystal growth can occur to obtain the desired product. According to the present invention, a round, dense powder olefin polymerization catalyst TiCl ₃ nMClm with an average particle diameter in the range of about 10 to 200 microns (where n is about 0.15
~0.50 is any number from about 0.3 to 1.0). The present invention includes the following steps. (a) a preformed solid "seed" catalyst having nearly the same chemical composition as said catalyst product, but more finely divided than said product, and TiCl ₄ and R ₂ Mg, RMgX; , NaR, MRm
or a reducing agent selected from RxMXm-x (wherein R is a _C1 - _C5 alkyl group, Mg is magnesium, X is Cl, Br or I,
M is Al or a metal of group A, A, B or A of the periodic table, m is the valence of M, and x is an integer equal to or smaller than the valence of M. ) in a suitable inert diluent in which both TiCl ₄ and the reducing agent are soluble, but the seed catalyst is insoluble, at a temperature sufficiently low that the rate of reduction of the TiCl ₄ is negligible. In, form. (b) Heat the mixture at a controlled slow rate of 0.2°C/min to 2.0°C/min while mixing until reaching +25°C. Ziegler-type catalysts from TiCl ₄ are preferably prepared with several reducing agents, each producing a reduced TiCl ₃ -nAlCl ₃ catalyst. The value of n varies depending on the reducing agent used. When using diethyl aluminum chloride (DEAC) as the reducing agent, n
ranges from about 0.15 to 0.50, and theoretically n is 0.5
It can be, but it is usually between 0.28 and 0.43. When ethylaluminum dichloride (EADC) is used, the value of n will be 0.3 to 1.0. Usually the higher the _AlCl3 content, the higher the catalyst activity (expressed in grams of polymer product relative to the grams of catalyst used)
decreases. If an excess of reducing agent is used, a catalyst with reduced AlCl ₃ content can be obtained, but the particle size will be smaller. Strictly speaking, solid catalysts are “seeds” for crystal formation.
isn't it. This is because even if the α-isomer is used as a "species" in the present invention, the product will be produced by α- and β-isomers in the same way as when the β-isomer is used.
This is because the data shows that it will be a mixture of TiCl ₃ . If a true crystal seed is included, the resulting crystal will have the same form as the seed. For example α
- species, an α-product is produced. Furthermore, the amount used must be much greater than the amount effective in crystal seeding. However, for simplicity of terminology, the solid catalysts will be referred to as "seed" catalysts below. As the "seed" catalyst, a pre-prepared catalyst with a wide or narrow particle size distribution or a catalyst "fine powder" obtained by a classification operation can be used. A "seed" catalyst can suitably be produced in the first step of a two-step process. This two-stage process uses the same reactor for both stages, but the first stage has a "holding time" to ensure that substantially all of the TiCl ₄ is reduced before stage two begins. time) to complete the process. Several reduction/crystallization steps can be repeated until the desired average particle size is obtained. Preferably, the reduction in the presence of a seed catalyst is carried out 3 to 9 times. Generally, the same reaction conditions used in the reduction/crystallization step using the seed catalyst are used to generate the catalyst species. These conditions are described below. The seed catalyst has nearly the same structural formula as the final product and may have a wide or narrow particle size range. Examples of seed catalysts are shown in the table. Example of seed catalyst Formula: TiCl ₃ 0.37ALCl ₃ Catalyst form: β Average diameter: 18μ Size distribution: 15-21μ The amount of seed catalyst used is the total amount of catalyst obtained from the reduction/crystallization step using the seed catalyst Based on.
(In multi-stage operations, the solid catalyst present at the beginning of each reduction stage is
All this is considered to be a seed catalyst. ) seed catalyst per 100 parts by weight of total catalyst obtained from the reduction/crystallization step (i.e. seed + freshly formed catalyst)
~75 parts by weight, preferably 20-40 parts by weight are used. That is, 0.33 to 99 parts by weight per 1 part by weight of seed catalyst,
Preferably 1.5 to 4 parts by weight of fresh catalyst are produced. As noted above, the reaction conditions generally vary according to the present invention, regardless of whether a seed catalyst is being produced (i.e., produced as a first step), or whether it is agglomerated or not, and whether the catalyst is is the same whether or not it is generated. Reaction conditions are selected to promote crystal growth without excessively forming new crystal nuclei. By mixing the reagents at low temperatures where only slight reduction occurs, the amount and rate of reduction can be controlled by the heating rate of the reagents. Thus, temperature and heating rate are very important variables in this invention. The mixture is heated between -40°C and +15°C, preferably between -5°C and
Forms in the temperature range of -30°C. When using EADC as the reducing agent, mixing temperatures as high as 25° C. can be used. This temperature limitation is due to the fact that above 15°C (25°C for EADC) new nuclei begin to form, and these small nuclei generate an excessive amount of catalyst fines. −
Since the reaction rate is negligible at 40℃, −40
Temperatures lower than °C are not required. Therefore, the reaction mixture is heated at 0.2 to 2.0°C/min, preferably about 0.5°C, until reaching a holding temperature of 15°C to 40°C (preferably about 30°C).
Heat at a rate of °C/min. Stir the mixture for 0-2 hours (preferably about 30 minutes) to complete the reaction.
Keep at this temperature. The activation temperature is used to change the crystal form of TiCl ₃ from the β form (or a mixture of α form and β form) to α-TiCl ₃ . This activation step can also be carried out without stirring, as discussed in more detail below. Pressure is not critical. Typically 10-140 psig
(0.7-9.8 mg/cm ² ), preferably 14 psig (0.98 mg/cm 2 ), preferably 14 psig (0.98 mg/cm 2 )
^cm2 ) range. It is only important that sufficient pressure be used to maintain the solvent in the liquid phase. The reduction/crystallization step is carried out by suspending the seed catalyst in an inert reaction diluent that acts as a solvent for the TiCl ₄ and reducing agent, but not for the catalyst product. Typical diluents to be used are linear or branched paraffinic hydrocarbons having 5 to 12 carbon atoms, such as heptane and isooctane, which are substantially free of aromatic hydrocarbon impurities. The table shows test results for isooctane diluents suitable for this method. Table Isooctane diluent 2,2,4-trimethyl bentane 78.8vol.% 2,3-dimethyl pentane 7.9 2,4-dimethyl pentane 6.2 2,5-dimethyl hexane 1.5 2-methyl hexane 1.4 3-methyl hexane 1.1 2,4 -Dimethyl hexane 1.1 Other isoparaffinic compounds 2.0 TiCl ₄ and the reducing agent should be a solution in an appropriately selected diluent. It has been found that as the concentration of reactants decreases, the catalyst particle size increases, but at the same time the density of the catalyst particles decreases. EADC can also be used in combination with DEAC, but below are examples of reducing agents:
Use DEAC. When using EADC,
A mixture of 3 to 4 parts DEAC and 1 part EADC is preferred. Preferably, a DEAC solution is first prepared and the seed catalyst is suspended therein. DEAC concentration in solvent is
It ranges from 0.1 to 7 mol, preferably from 0.5 to 1.0 mol. _TiCl4 solution is 0.5-4 molar, preferably 1.5
~2.0 molar concentration. The solution is added to the seed catalyst suspension in DEAC solution over a mixing time of 10 seconds to 4 hours, preferably about 30 minutes, while maintaining the reaction zone at a low temperature. Preferably, a seed catalyst is present when adding the TiCl ₄ solution. To obtain the benefits of the present invention, it is important that a seed catalyst is present when reducing _TiCl4 . The amounts of _TiCl4 solution and DEAC solution are such that the molar ratio of _TiCl4 to DEAC is between 2.0 and 0.5, preferably about 1.3.
Select so that The working variables are shown in the table.

[Table] In case of refund

[Table] Average particle diameter (μ) 20 200 24～4
7
Mixed It is important to perform the reduction/crystallization reaction in a well-mixed reactor to achieve good dispersion of the seed catalyst and to promote the production of relatively large, rounded catalyst particles. UK patent no.
No. 1139450 provides good guidance on the mixing conditions to be used. The amount of mixing energy must be determined depending on the reactor used, since catalyst fines will be produced if the mixing energy is too small or too large. Energy amount (watts/
) depends on the structure of the reactor, the shape of the blades, the arrangement of baffles, and the viscosity of the solution. The optimum value can be determined by experiment. Generally 100~
300W/ is appropriate. Flat blade turbine impellers are generally preferred. In vessels with L/D ratios greater than 1, the number of impellers required is approximately equal to the L/D ratio. for example,
When the L/D ratio of the reactor is 1.9, the two impellers are
The reactor is spaced apart and mounted on a drive shaft to provide good mixing throughout the reactor. An example of the design is shown below for reference. A six-blade turbine impeller was mounted 10 inches from the bottom in a Pfaudler reactor with an internal diameter of about 18 inches and an L/D ratio of about 1.0. Each vane is flat and mounted at an approximately 45° angle. The entire diameter of the impeller was approximately 14 inches (approximately 36 cm).
Good results were obtained using two complete baffles mounted 180° apart and operating at 100-150 rpm. The mixing energy input under these conditions was approximately 100-300 W/. The baffle extends 1 inch (2.54 cm) inwardly from the vessel wall, extends approximately 2 inches (5.08 cm) radially of the vessel, and extends vertically the entire length of the reactor. Ta. Mixing must continue during the mixing, heating and holding stages, and may continue during activation. The present invention uses one or more (preferably 3 to 9) sequential reduction/crystallization steps in the presence of a seed catalyst. The initial seed catalyst can be prepared according to the instructions given in GB 1139450 or as described in the reduction step herein (but omitting the addition of the seed catalyst). can. Thus, the mixing, heating and holding steps can be performed to obtain a first catalyst product with or without a narrow particle size range. A holding step must be used to complete the reduction reaction. Preferably, the first catalyst product is separated from the reaction liquid, for example by decanting the reaction liquid with a dipleg, before introducing the reactants for the reduction/crystallization step. TiCl ₄ and
It is preferable to decant the liquid before each addition of DEAC. Alternatively, the reaction solution can be left in place. In either case, the contents of the reactor are cooled to the mixing temperature (-40 to +15 °C) and the TiCl ₄ and
DEAC is added in the proportions and concentrations indicated above (ie, if diluent remains in the reactor, the molar concentration of the influent must be suitably high). Diluents can also be added if desired. The newly added TiCl ₄ in the reactant stream is 0.2 to 4.0 moles (preferably about 1 mole) per mole of TiCl ₄ initially added. The reaction mixture is then heated at a controlled rate of 0.2-2.0°C/min to a final temperature of about 25-45°C, preferably
Heat at a rate of 0.5°C/min to a holding temperature of 40°C.
Catalyst fines will be seen in the supernatant unless the holding temperature is at least 40°C during the holding time. To prevent this, a final temperature of 40°C must be used. If this small amount of fines is acceptable, a relatively low temperature range of 25-40°C can be used. The holding time can be as long as 2 hours to ensure complete reduction of TiCl ₄ . Preferably, the holding time is at least 30 minutes at 40°C. Agitation is maintained at the same speed during the hold time as during the mixing and heating stages. Excessive energy input in the holding stage results in the production of catalyst particles with a smaller average diameter than would otherwise be obtained. The product obtained by the process of the invention is a compact catalyst that is substantially spherical with large particle size and a narrow size distribution. The final average particle size (and size distribution if the seed catalyst has a wide particle size range) is determined by the number of times the catalyst undergoes the reduction/crystallization step. The enlarged photograph shows that agglomeration of catalyst fines occurs in the method of the invention. Thus, simple catalyst growth is not provided in the present invention. These photographs also show that the agglomeration produces rounded or spherical catalyst particles, thus producing polymer powders of almost identical shape. The following examples are provided to illustrate the invention.
In each case, catalyst formation was carried out by reduction and crystallization in the apparatus described below and according to the method described below. 500ml without baffle with flat blade stirrer, thermometer and another inlet
Cool the round bottom flask to −30° C. in a dry ice/isooctane bath. The stirrer is placed at an angle of 180°.
It is equipped with two blades and has a total diameter of 6 cm. The entire apparatus and all catalyst materials are kept under inert gas. Add diethylaluminum or other reducing agent (in n-heptane) to a cooled flask.
1.0-1.5 molar concentration). Stir the diethyl aluminum chloride solution at a speed of 210-400 rpm.
The stirring speed was kept at a certain value throughout the production, i.e. 250
Keep it as close to ±10rpm as possible. _TiCl4 (1.5-2.0 molar, in n-heptane) is added to the diethyl aluminum chloride solution at a rate of 3 mmol/min. When total TiCl ₄ solution is added (1.33 mol TiCl ₄ per 1 mol diethyl aluminum chloride),
The mixture is heated to +40°C at a rate of 0.5°C/min.
The reaction mixture is maintained at this temperature for 1 hour with stirring. At this point, the reaction mixture may be heated linearly to the activation temperature or cooled to room temperature until time for high temperature activation. After aging at 40°C, the catalyst is filtered, washed twice with heptane (using 0.005% diethyl aluminum chloride solution in heptane for all washes), and transferred to a glass polymerization tube containing a magnetic stirrer. Resuspend in medium heptane. The amount of heptane used for washing and resuspension is usually three times the volume of catalyst. The sealed vessel containing the reaction mixture is heated to 160° C. for 1 hour. After aging for 1 hour at 160°C, the mixture is cooled for 2-4 hours. The catalyst may or may not be stirred during this heating. The filtered catalyst is washed twice with heptane and dried by removing the diluent under reduced pressure at room temperature. In the description of the invention, the produced catalyst is separated from the reaction mixture and before heating for activation:
The reduction/crystallization step can also be repeated three times (Examples 5 and 6). During the total crystallization and reduction reactions involving both stages of the present invention, the reaction mixture was
The mixture is stirred by an impeller with a diameter of . Torque force is 10~
It can range from 25 inch-ounces (720 to 1800 g-cm). Example 1 A solution of titanium tetrachloride at 2.274 mmol/ml in n-heptane was prepared;
A 1.6106 mmol/ml diethyl aluminum chloride solution was prepared. TiCl ₄ solution 77c.c. (170.55 mmol) and diethyl aluminum chloride solution 79.42cc
(127.91 mmol) was prepared at -30°C. The molar ratio of TiCl ₄ to diethyl aluminum chloride in this mixture was about 1.33. To this was added 0.70 g of finely divided TiCl ₃ .1/2AlCl ₃ , which was in a negligibly small proportion of 2% by weight based on the total catalyst finally produced. The mixture was produced by adding the TiCl ₄ solution to the diethyl aluminum chloride solution at a rate of 0.8 cc/min. During the addition and throughout the remainder of the reaction, the stirring speed was approximately
It was maintained at 250 rpm. The temperature is increased at a rate of about 0.5°C/min to a final temperature of about 40°C, at which point heating is terminated. The catalyst was filtered, washed with n-heptane and resuspended in heptane. The catalyst was examined and found to have a particle size distribution of approximately 13-31μ. It had a wide particle size distribution, an irregular shape, and a black color. This indicates that using about 2% by weight of preformed catalyst is insufficient if only a single reduction stage is used in the present invention. Example 2 In this example as well, a solution of titanium tetrachloride in n-heptane and a solution of diethyl aluminum chloride in n-heptane having the concentrations given in Example 1 were used.
A mixture of 75 c.c. (170.6 mmol) of TiCl ₄ solution, 79.4 cc (127.9 mmol) of diethyl aluminum chloride solution and an additional 79.4 cc of n-heptane was added to the diethyl aluminum chloride solution and 1.6 c.c.
It was prepared by addition at a temperature of -30°C at a rate of cc/min. The stirring speed was 300 rpm. The reduction reaction was carried out in the same manner as in Example 1. After obtaining a crystalline product by raising the temperature to +40°C and aging for 30 minutes, the solution was cooled again to -30°C and 70.0 cc of titanium tetrachloride solution and 79.4 cc of diethyl aluminum chloride were added.
Added cc. Increase the temperature again to +40 at a rate of 0.5°C/min
The temperature was increased to a final temperature of 0.degree. C. and aged for 1 hour. The catalytic product obtained from this reduction reaction has an average diameter of
It was spherical and black in size with a narrow particle size distribution of 28μ. Although the catalyst structure did not appear to be quite dense like other products of the invention, there was no structural "looseness". This product was then activated as previously described herein and used to polymerize propylene, which was polymerized for 2 hours at 65°C in n-heptane as the reaction diluent and the catalyst It was found to be an excellent catalyst for the polymerization of polypropylene, since 27 g of polypropylene was obtained per gram. The product contained 96% by weight of material insoluble in boiling n-heptane. This indicates high crystallinity. The intrinsic viscosity was 2.74. Example 3 To illustrate the use of a preformed catalyst, this example uses a small particle size, irregularly shaped catalyst with a wide size distribution as a feedstock in the second stage of the reduction/crystallization described in Example 2. We will describe the method used as In this example, 4.16 _g of a preformed titanium trichloride catalyst of formula _{TiCl3.0.33AlCl3} was dissolved in 86.05 mmol (53.5 cc) of the diethyl aluminum chloride solution described in Example 1 with 54 c.c. of additional n-heptane. was added and suspended. To this mixture was added 0.8 cc/50 c.c. (113 mmol) of the titanium tetrachloride solution described in Example 1.
Added at a rate of minutes. The mixture was initially brought to a temperature of -30°C while stirring at a speed of 240 rpm. The mixture was then heated to about +40°C at a rate of 0.5°C/min and then aged at 40°C for about 1 hour. The original catalyst had a wide particle size distribution and a large amount of catalyst fines, but the product from this experiment was approximately
It had an average particle size of 16μ, a narrow particle size distribution, an irregular shape, and a black color. The structure was precise. Although the shape of the catalyst particles was irregular, it was not as irregular as the original catalyst, and repeating this step would be expected to yield a regularly shaped product with a large average diameter. The seed material and solvent are maintained below +5°C, preferably below -15°C during mixing. It has also been discovered that although diethylaluminum chloride is the reducing agent of choice, large particle sizes can be obtained by adding small amounts of ethylaluminum dichloride. Therefore, it is preferred that ethylaluminum dichloride does not account for more than 25% of the reducing agent and the rest is diethylaluminum chloride, although it is also possible for the reducing agent to contain 0 to 100% diethylaluminum chloride. In other cases, the preferred reducing agent can be mixed with triethylaluminum in an amount having a ratio to diethylaluminum ranging from 0 to 0.25. Example 4 In this example, the catalyst is first prepared, separately regenerated, and then processed in the second stage of the invention described above. n-heptane solution in titanium tetrachloride as described in Example 1
(2.27 molar concentration) containing 20 g of catalyst prepared and separated as above at a rate of 1.61 cc/min.
Added to 160 c.c. of diethyl aluminum chloride solution (0.8 molar in heptane). total reaction mixture
at −30 °C while adding _TiCl4 solution.
Stirred at a speed of 250 rpm. After the addition, the reaction mixture is heated at a controlled rate of 0.5°C/min until the reaction temperature reaches +40°C. The amount of separated catalyst is
After reaching 98% theoretical yield, the mixture was heated to +40°C for 1 hour.
Stir at ℃. The catalyst particle size distribution is narrow. Example 5 In this example, a catalyst was prepared by a multiple shot technique as described below. TiCl ₄ in n-heptane and AlEt ₂ Cl in n-heptane solutions of the concentrations given in Example 1 were used in this example as well. AlEt ₂ Cl solution 79.4cc
(127.9 mmol) and an additional 79.4 cc of n-heptane (resulting in a concentration of AlEt ₂ Cl of approximately 0.8 mmol/ml) was prepared. Approximately 75 c.c. of TiCl ₄ (170.6 mmol) was added to the AlEt ₂ Cl solution at a rate of 1.6 cc/min at a temperature of -20°C. The TiCl ₄ /diethyl aluminum chloride molar ratio was about 1.33. The stirring speed was 250 rpm. Example 1 is the reduction reaction.
In the same manner as above, the temperature was raised to +40°C and aged for 30 minutes to obtain a crystalline product, and then the solution was cooled again to -30°C. This catalyst product is the preformed catalyst used in the present invention. Add 17.9 cc of concentrated AlEt ₂ Cl solution (in n-heptane) to the reaction mixture.
7.155 molar concentration) was added. The stirred reaction mixture was then charged with 37.6 cc at −30°C for 20 min.
A concentration of TiCl ₄ (4.55 molar in n-heptane) was added. The temperature was increased again at a rate of 0.5°C/min to a final temperature of +40°C and aged for 30 minutes.
The molar ratio of TiCl ₄ /diethyl aluminum chloride is approximately
It was 0.75. The previous step was repeated two more times.
The catalyst product obtained from the final reduction reaction was black and spherical with an average diameter of 24μ. Changes in catalyst particle size due to continuous reactions are shown in the table below. Example 6 A solution of 75 c.c. of _TiCl4 in n-heptane (2.274 molar) was prepared and to it was added a solution of 135 c.c. of _AlEtCl2 in heptane (1.89 molar). The mixing temperature is -
At 20℃, the stirring speed in the reactor with a young plate is
It was hot at 240 rpm. Reduction was performed in the same manner as in Experiment 1. The reduction reaction was carried out in the same manner as in Example 1, and after obtaining a crystalline product by raising the temperature to -40°C and aging for 30 minutes, the solution was cooled again to -20°C, and the solution was
Add 135 c.c. of AlEtCl ₂ solution (1.89 in n-heptane)
molar concentration) was added. Then 37.6 cc of TiCl ₄ in n-heptane (4.55 mol) was added over 20 minutes. The temperature was increased again at a rate of 0.5°C/min to a final temperature of +40°C and aged at this temperature for 1 hour. The second reaction described immediately above was repeated two more times. The catalyst product obtained from the fourth reduction reaction is 47μ
The particle size distribution was narrow, and the particle size was black and spherical. The catalyst structure was dense. The change in catalyst diameter as a result of each successive reduction is shown in the table below to illustrate the invention.

[Table] It is clear from the table that relatively large catalyst particles are obtained according to the present invention, and that the particle size distribution is narrow even when the preformed catalyst has a wide particle size distribution. Although AlEt ₂ Cl, AlEtCl ₂ and AlEt ₃ or mixtures thereof are preferred organometallic reducing agents, suitable organometallic reducing agents include R ₂ Mg, RMgX, NaR,
MRm or RxMXm-x (where R is a _C1 - _C5 alkyl group or substituted alkyl group, Mg is magnesium, X is Cl, Br, or I, M is Al or A, A, B of the periodic table) or a metal group of Group A, m is the valence of M, and x is an integer equal to or smaller than the valence of M). Additionally, although preferred activation temperatures and times are listed in the table, a broad operational range of activation is 90-185°C for times of 20 minutes to 5 hours. Furthermore, although average particle diameters in the range of 20-200μ are standard, there are rare cases where average particle diameters as small as 10-30μ may be exceptionally useful. This occurs when TiCl ₄ is reduced in the first stage with AlET ₃ , which is an unusual case in which very small catalyst particles are produced, ie particles with an average diameter of about 3μ. However, these relatively small particle catalysts are extremely active. Moreover, they can be enlarged to a satisfactory size by the technique of the present invention. Thus, the first stage reduction of TiCl ₄ with AlET ₂ Cl produces catalyst particles with an average particle size in the range of about 3μ. These 3μ sized particles are reduced to a satisfactory average particle diameter, i.e., by a series of reduction/crystallization steps, e.g.
It can be made as large as 10μ. Further examples of embodiments of the invention are described below. (1) A method according to claim 1, characterized in that the reducing agent is selected from diethylaluminum chloride, ethylaluminum dichloride, triethylaluminum and mixtures thereof. (2) The method according to claim 1, wherein the average particle diameter range is from 20 to 200μ. (3) The method according to claim 1, wherein the average particle diameter range is 10 to 50μ. (4) performing the reduction step using a catalyst produced as a "pre-formed catalyst" during the previous reduction step;
The method according to claim 1 and items (1) to (3) above, characterized in that the method is carried out successively at least twice. (5) Reaction conditions in one or more steps range from -40℃ to +
Claim 1 and items (1) to (4) above, characterized in that the method includes a starting temperature of 15°C, a heating rate of 0.2 to 2.0°C/min and a holding temperature of 25 to 45°C. Method. (6) Repeat steps A and B at least twice, and after the completion of the last repetition, the catalyst product is
The method according to claim 1 and items (1) to (5) above, characterized in that activation is carried out at a temperature of 185° C. for 20 minutes to 5 hours. (7) The temperature is 145-185℃ and the time is 30℃.
The method according to item (6) above, characterized in that the heating time is 120 minutes. (8) The method described in items (1) to (7) above, wherein the reducing agent is diethyl aluminum chloride. (9) The method described in items (1) to (7) above, wherein the reducing agent is ethylaluminum dichloride. (10) The method described in items (1) to (7) above, wherein the reducing agent is triethylaluminum. (11) The method according to items (1) to (7) above, wherein the reducing agent is a mixture of diethyl aluminum chloride and ethyl aluminum dichloride. (12) The diluent is n-heptane and the concentration of TiCl ₄ is approximately
4.55 molar, the concentration of diethyl aluminum chloride is about 7.15 molar, and the diethyl aluminum chloride is first mixed with said additional diluent to dilute to 3-5 molar and then compared to said diluted diethyl aluminum chloride. 3. Process according to claim 2, characterized in that the TiCl ₄ solution is added at a relatively slow addition rate. (13) Mixing temperature is approximately -20℃, heating rate is approximately 0.5℃/
minutes, a holding temperature of about +40°C, a holding time of about 30 minutes, and the mixture is cooled to about -30°C before repeating the reduction, heating and holding steps 3 to 9 times. The method described in paragraph (12). (14) The method according to item (13) above, characterized in that the TiCl ₄ solution is added over about 20 minutes so that the total mixing energy input is 100 to 300 W/.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the steps for preparing the catalyst described in the present invention.

Claims (1)

[Scope of Claims] 1 TiCl ₃ .nAlCl ₃ olefin polymerization catalyst product which is rounded and dense particles having an average particle size of 10 to 200μ (where n is as known per se)
It is either 0.15-0.50 or 0.3-1.0. ), which comprises the following steps: (1) One part by weight of a finely divided preformed solid catalyst having essentially the same chemical composition as the desired catalyst product is added to a titanium tetrachloride concentration. A diluent solution of titanium tetrachloride with a concentration of 0.5 to 4 molar, formula
The _{concentration of} one _{or more} reducing agents represented by AlR p A diluent solution having a molar concentration of 0.1 to 7 molar (however, the diluent of the titanium tetrachloride diluent solution and the reducing agent diluent solution is a diluent solution in which the titanium tetrachloride and the reducing agent are soluble, but the catalyst is insoluble). and an additional diluent selected from _C5 to _C12 paraffin hydrocarbons and mixtures thereof. and −40℃〜−
(2) heating said mixture at a controlled low rate of 0.2-2.0°C/min with good mixing until a holding temperature of 25-45°C is reached; (3) ) The mixture is held at the holding temperature for 0 to 120 minutes with good mixing to substantially complete the reduction reaction, and 1.5 parts by weight of the preformed solid catalyst is maintained at the holding temperature for 0 to 120 minutes.
(4) repeating steps (1) to (3) as necessary, and (5) heating the resulting catalyst product at 90 to 185°C for 30 minutes. Activation process by heating for ~120 minutes.