JPH0125762B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an olefin polymer,
More specifically, it relates to a method for producing a polyolefin with a wide molecular weight distribution, which involves controlling the average molecular weight and molecular weight distribution of the resulting polymer over a wide range by carrying out the polymerization reaction of the olefin in several polymerization steps with different reaction conditions. It is something. Generally, when polyolefin resin is used to manufacture molded products such as bottles, tubes, films, and sheets by blow molding or extrusion molding, solid physical properties are It is necessary to select a uniform polyolefin resin as a raw material that has both properties. The polyolefin resin herein refers to an olefin homopolymer or a copolymer with another olefin, which will be described in detail later. In this type of polymer, there is a relationship in which increasing the molecular weight improves the solid physical properties but decreases the fluidity, and conversely, decreasing the molecular weight improves the fluidity but decreases the solid physical properties. Since it is difficult to obtain polymers with desirable properties,
Instead, a method has been adopted in which the resin is molded as a suitable mixture of a high molecular weight component and a low molecular weight component, in other words, a method in which the molecular weight distribution of the resin is widened. For example, a method that directly realizes this idea is to manufacture a high molecular weight polymer and a low molecular weight polymer separately and mix them uniformly in a specific ratio to create a resin composition with a wide molecular weight distribution. There are so-called polymer blends. Various methods have been proposed for this mixing, ranging from simple fusion of resin powder mixtures to melt kneading or melt mixing. Differences in melt fluidity based on the composition of the polymers are particularly impediments to uniform mixing, so this physical mixing method requires extensive mixing as the molecular weight difference between the polymers to be mixed is large. The drawback is that it requires equipment, materials, and operating energy, reducing its practicality. In contrast to the above-mentioned physical method, there is a chemical method in which the polymer produced in the polymerization reaction itself forms a polymer with a wide molecular weight distribution, and the following two types of methods are known. The first method is to produce a polymer with a wide molecular weight distribution simply by polymerizing under a single reaction condition, and usually a catalyst with a variety of active sites etc. is used to suit the purpose. It is essential to Since the broadening of the molecular weight distribution in such a method depends mainly on the selection of the catalyst, some improvement proposals regarding so-called Ziegler-type catalysts have been made in line with this kind of demand; There is a limit to the breadth of the molecular weight distribution of the produced polymer, and it cannot be said that it is necessarily at a level that is satisfactory for some molding applications. Additionally, catalysts that produce polymers with a wide molecular weight distribution tend to have problems such as slightly inferior activity and a portion of the produced polymer adhering to the reactor wall. The use of catalysts tends to be associated with the disadvantage of loss of productivity. On the other hand, highly active catalysts that are free from the above-mentioned problems are almost exclusively those that produce polymers with a narrow molecular weight distribution. Therefore, as a second method, the polymerization reaction is divided into several polymerization steps, and the reaction conditions are changed so that polymers with different molecular weights are produced in each step. A method is proposed below in which an olefin is introduced and polymerized to produce a polymer with a wide overall molecular weight distribution. This type of method is used, for example, in JP-A Nos. 54-7488, 54-146885 and 52-
It is disclosed in specifications such as No. 19788.
That is, in JP-A-54-7488, in the presence of a supported highly active Ziegler catalyst, olefin polymerization is carried out in the first stage reactor in a pressurized state filled with liquid and at a lower hydrogen concentration than in the subsequent stage. , the polymerization reaction mixture in which high molecular weight polymer particles are dispersed in the melt is continuously transferred as it is to the second stage reactor under differential pressure without separating the components.
A method is disclosed in which olefin is polymerized in the presence of hydrogen in a stage reactor to produce a low molecular weight polymer, and the desired polymer is recovered from the reaction mixture in the latter stage. Compared to the known method of producing a high molecular weight polymer in the latter step, which caused gel formation and strength loss in the molded product, this method does not have such problems, and the known method of producing the polymer in the same order as the same method. It was explained that the method did not include the knowledge of pressurization by liquid filling as shown in the method, and did not indicate a continuous production method in which the pressure of the reactor and the monomer concentration, that is, the polymerization rate were adjusted separately. has been done. Furthermore, JP-A-54-146885 describes a method for polymerizing ethylene-based olefins in two successive stages under different hydrogen partial pressure conditions.
In the presence of a highly active catalyst consisting of a solid catalyst component, which is a hydropolysiloxane, a Grignard reagent, an aluminum alkoxy compound, and a halogen-containing compound of titanium/vanadium, and an organometallic compound as a catalyst, the molar ratio of ethylene to hydrogen is 1
1:1-8 in stage, 1:0-0.3 in second stage
Discloses a method for polymerization under the conditions of 1 to 2, which overcomes conventional methods that have not been able to significantly adjust the molecular weight distribution while maintaining high productivity due to low catalytic activity and limited solution viscosity. It has been shown that this problem can be solved by using a highly active catalyst in this method. Furthermore, JP-A-52-
No. 19788 describes how a reactor that produces high molecular weight polymers by lowering reaction conditions such as temperature and hydrogen concentration, and a reactor that produces low molecular weight polymers by raising those reaction conditions, are separated by a circulation path. A cyclical process in which the reaction suspension containing the polymer discharged from one reactor is fed to the other reactor, and the suspension discharged from the latter reactor is again fed to the former reactor. discloses a method for producing a polymer consisting of both high and low molecular weight components as a whole by introducing and polymerizing an olefin, a catalyst, and an inert solvent. Although there are differences in the above methods such as the reaction conditions for producing high molecular weight polymers and low molecular weight polymers, the order of production, the ratio of production, and the polymerization operation method,
In either case, the catalyst used in the first stage is transferred as a reaction mixture containing a polymer to the second stage and used again, so that the same catalyst is involved in the production of the polymer in both the front and the front stages. Furthermore, in order to produce a target polymer with a constant average molecular weight and molecular weight distribution through such two-stage polymerization, it is necessary to accurately control the molecular weight and amount of the produced polymer in each polymerization step. is essential. However, even though the molecular weight can be controlled independently by temperature and hydrogen concentration under one catalyst, the amount produced depends on the molecular weight controlling factors, such as temperature and hydrogen concentration, as well as the catalyst usage history and catalyst poison. Since it is largely controlled by the catalytic activity, which is significantly affected, there are limits to controlling it by the monomer concentration and reaction time, which have a complementary relationship. It is extremely difficult to significantly control body concentrations and reaction times. This relationship originally means that there are restrictions on molecular weight control itself, especially in conventional methods where the reaction conditions in the first and second stages are polarized.
Not only does the change in catalytic activity in the latter stage be significant, but the disadvantage that the history of catalyst use in the earlier stage disturbs the stability of the catalytic activity in the latter stage may be amplified, making it possible to arbitrarily control the molecular weight distribution over a wide range. However, it is difficult to meet the demand for producing the desired polymer with good reproducibility. Furthermore, as long as such a serial multi-stage process is used, a process with three or more stages becomes impractical, and the practical limit is to obtain a polymer consisting of both high and low molecular weight components by a two-stage process. If the difference in molecular weight is too wide, a problem may arise in that the uniformity of the target polymer is impaired. The purpose of the present invention is to solve the above-mentioned problems in conventional methods, perform polymerization without using any special control method in several polymerization steps with different reaction conditions, and improve the average molecular weight and molecular weight distribution of the target polymer. It is an object of the present invention to provide a method for producing a polyolefin having a wide molecular weight distribution, which can be precisely and easily controlled over a wide range. Another object of the present invention is to develop highly active catalysts that have extremely high catalyst activity and have good polymer particle properties, but only a polymer with a narrow molecular weight distribution can be obtained under a single reaction condition. An object of the present invention is to provide a method for producing a polyolefin, which can be advantageously used as a catalyst for producing a polymer having a wide molecular weight distribution. Another object of the present invention is to transfer a reaction mixture from an earlier step under conditions of low partial pressures of monomers and hydrogen to a later step under conditions of high partial pressures of monomers and hydrogen in conventional methods. If the order of the above steps is reversed, special transfer means will be required to counteract the differential pressure against the flow, and if the order of the above steps is reversed, special transfer means will be required to prevent hydrogen in the mixture from flowing from the previous stage to the subsequent stage. It is an object of the present invention to provide a method for producing a polyolefin, which alleviates incidental problems such as the need for a means for removing hydrogen under reduced pressure, and which comprises a multi-stage polymerization process that does not require special measures. In order to achieve the above objectives, the present inventors have completed the present invention based on the following new findings as a result of intensive research. That is, the present inventors discovered that in the presence of the same type of catalyst common to each polymerization step,
After producing high and low molecular weight polymers in separate polymerization steps, the reaction mixtures still containing these polymers are combined into a single reaction mixture and subsequently treated in the presence of the reaction mixture. By producing a polymer with a molecular weight located in the middle of the molecular weights of each of the above polymers (referred to as an intermediate molecular weight polymer), it is possible to obtain a uniform polymer with a wide overall molecular weight distribution and less gel or stickiness. I was able to discover the facts.
It is not clear why a homogeneous polymer can be obtained by this method, but based on various findings, it is possible that the polymer is retained near the catalyst and that the newly formed polymer is If it is formed by stacking on the outside of the previously existing polymer, even if there is a high molecular weight polymer or a low molecular weight polymer on the inside, the outside is all occupied by the same intermediate molecular weight polymer, so the individual It has the effect of improving the compatibility, that is, dispersibility, between polymer particles, and furthermore, because this mediating intermediate molecular weight has a molecular weight located in the center of the molecular weights of each polymer, high
It is assumed that compatibility can be maintained with both low molecular weight polymers. The gist of the present invention based on the above findings is as follows. That is, in the presence of a Ziegler-type catalyst improved to have high activity, an inert solvent, and a molecular weight regulator, at least one type of olefin is introduced and polymerized in several polymerization steps with different reaction conditions. In the method for producing polyolefins with a wide molecular weight distribution, which involves controlling the average molecular weight and molecular weight distribution of the polymer over a wide range, first, in the presence of the same type of catalyst common to each polymerization step, the concentration of the molecular weight modifier is and a polymerization step (A) in which at least one type of olefin is introduced and polymerized to produce a relatively high molecular weight polymer under reaction conditions in which at least one of the reaction temperatures is kept at a low level, and the above catalyst. A polymerization step in which at least one type of olefin is introduced and polymerized to produce a relatively low molecular weight polymer under reaction conditions in which at least one of the concentration of a molecular weight regulator and the reaction temperature is maintained at a high level in the presence of a polymer. B) is polymerized in at least two polymerization steps, and then the reaction mixtures containing the polymers in each of the above polymerization steps are mixed to form a new single reaction mixture, and in the presence of the molecular weight modifier, In each of the above polymerization steps, at least one type of olefin is introduced and polymerized under reaction conditions in which at least one of concentration and reaction temperature is maintained at an intermediate level compared to the reaction conditions set in each of the above polymerization steps. Polymerization is carried out in the polymerization step (C) to produce a polymer with a molecular weight located in the center with respect to the molecular weight of the produced polymer, and the production ratio of the polymer in each polymerization step to the desired polymer is determined by The reaction mixture still containing the polymer in the above polymerization step (C) as 25-70 wt% in step (A), 25-70 wt% in polymerization step (B) and 5-50 wt% in polymerization step (C). This is a method for producing a polyolefin with a wide molecular weight distribution, which is characterized by recovering a target polymer from a polyolefin. The content of the structure of the method of the present invention will be specifically explained below. The catalyst used in the present invention is not particularly limited as long as it has a sufficiently high activity; rather, when trying to obtain a polymer with a wide molecular weight distribution, it is necessary to use a catalyst with a molecular weight distribution under single reaction conditions. Even a highly active catalyst that can only yield a polymer with a narrow molecular weight distribution can be used without impairing the homogeneity of the polymer, as in the case of using a catalyst that yields a polymer with a relatively wide molecular weight distribution. For example, the following catalysts can be used. That is, a solid catalyst component which is a reaction product consisting of magnesium metal, an organic hydroxide compound, an organic oxygenated compound of a group a, a, or group a metal of the periodic table, or a halogenated compound thereof, and an aluminum halide; and a catalyst activating component which is an organometallic compound of a group metal. Here, the hydroxylated organic compounds include C ₂ H ₅ OH,
Alcohols or silanols such as C ₃ H ₇ OH, C ₄ H ₉ OH are preferred, and organic oxygenated compounds of metals in groups a, a and a of the periodic table include Ti
(OR) ₄ , V(OR) ₄ , Zr(OR) ₄ (in the formula, R represents an alkyl group), and the halogenated compounds are preferably TiCl ₄ , ZrCl ₃ , VOCl ₃ , etc., and aluminum halogen As compounds, Al(C ₂ H ₅ ) Cl ₂ ,
Al(C ₂ H ₅ ) ₂ Cl and the like are preferred. A suitable example of the preparation of a solid catalyst component using these reagents is given in
52-15110, JP-A No. 50-98585, JP-A No. 51-5384, and JP-A No. 52-39714. As organometallic compounds of periodic table and group metals, trialkylaluminum and dialkylaluminium hydride, which are organic compounds of aluminum, are preferred, including Al(CH ₃ ) ₃ , Al
Particularly preferred are (C ₂ H ₅ ) ₃ , Al(i-C ₄ H ₉ ) ₃ , Al(i-C ₄ H ₉ ) ₂ H, and the like. The same type of catalyst made by combining these catalyst components is commonly used in each polymerization step. Any inert solvent commonly used in the art can be used, but
Particularly suitable are alkanes having 4 to 20 carbon atoms, cycloalkanes such as isobutane, pentane, hexane, cyclohexane and the like. As the molecular weight modifier, hydrogen is preferred because it is effective and easy to handle. The olefin is represented by the general formula R-CH=CH ₂ (wherein R represents hydrogen or a linear or branched substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, particularly 1 to 8 carbon atoms). α-olefin is used. For example, ethylene, propylene, 1-
Examples include butene, 1-pentene, 1-hexene, etc. Among them, ethylene is particularly preferred, and it can be used alone or in a mixture with other α-olefins. The first stage of polymerization in the method of the present invention includes a polymerization step (A) in which a relatively high molecular weight polymer is produced and a polymerization step (B) in which a relatively low molecular weight polymer is produced.
At least two polymerization steps are carried out in parallel in the presence of the same type of catalyst in common. The reaction conditions in the polymerization step (A) include a temperature of 50 to 90°C, a pressure of 1 to 50 Kg/ ^cm2 , and a concentration of hydrogen as a molecular weight regulator of ethylene (both concentrations represent the concentration in an inert solvent). ) is selected to be one-half or less of that in the polymerization step (B), particularly preferably from 0 to 0.1 mol/mol. In addition, the reaction conditions in the polymerization step (B) include a temperature of 60 to 100°C;
Preferably, the temperature is 70 to 95°C, the pressure is 2 to 50 Kg/cm ² , and the hydrogen concentration is selected to be 0.01 to 1.0 mol/mol in terms of the concentration ratio to the ethylene concentration, as described above. here,
The molecular weights of both the high molecular weight polymer and the low molecular weight polymer can be selected with the goal that their average molecular weight matches that of the target polymer and that their molecular weight difference matches the width of the molecular weight distribution of the target polymer. is necessary. Next, in the latter stage of polymerization, the reaction mixture containing the polymer produced in each of the previous stages of polymerization is mixed to form a new single reaction mixture, and in the presence of the reaction mixture containing the polymer produced in each of the previous stages of polymerization, In the polymerization step (C), a polymer having a molecular weight located in the center with respect to the molecular weight of the polymer obtained is produced. Here, the polymer with the molecular weight located in the center is the molecular weight located in the center with respect to the peaks of the molecular weight distribution curves of both high molecular weight polymer and low molecular weight polymer drawn on the same drawing of semi-logarithmic graph paper. It has a peak in the distribution curve,
This also means that the mountain located in the center is a polymer in which the mountains located on the left and right overlap each other at least at their bases. The overlap of the bases of such peaks is a measure of the effect of improving the uniformity of the polymer, so if the polymers have a relatively wide molecular weight distribution that tends to overlap, even if the peaks of intermediate molecular weight molecules are small, It is easy to maintain uniformity,
On the other hand, if the polymers have a narrow molecular weight distribution that makes it difficult for them to overlap, it goes without saying that it will be difficult to maintain uniformity unless the pile of intermediate molecular weight molecules is increased; This can be dealt with by increasing or decreasing. The reaction conditions in the polymerization step (C) are at an intermediate level compared to the reaction conditions in the polymerization step (A) and the polymerization step (B), with a temperature of 50 to 100°C and a pressure of 1 to 50 Kg/ ^cm2.
And the hydrogen concentration is selected to be 0.001 to 0.5 mol/mol as the concentration ratio to the ethylene concentration as described above. The amount of polymer produced in each polymerization step is determined by the amount of olefin introduced in each polymerization step, such as the flow rate of ethylene, and the production ratio, that is, the content of each polymer relative to the target polymer, is
25-70wt% in polymerization step (A), polymerization step (B)
It can be carried out within the range of 25 to 70 wt% in the polymerization step (C) and 5 to 50 wt% in the polymerization step (C). The reactor used in each polymerization step can be appropriately used as long as it is commonly used in the technical field. That is, a stirred tank reactor and a recirculating tubular reactor can be used in any of the flow, semi-batch and batch methods of polymerization. However, the flow type tubular reactor is limited to the case where a flow type polymerization operation is performed.
In addition, for convenience when transferring the reaction mixture from the earlier step where the partial pressure of olefin is lower to the later step where the partial pressure of olefin is higher, at least in the polymerization step (A), a full-liquid type reactor is used where the total pressure can be easily adjusted regardless of the olefin concentration. It is preferable to use Here, the batch method in polymerization operation means that the catalyst is fed into the reactor,
The semi-batch method is a method in which raw materials for reaction such as inert solvents, molecular weight modifiers, and olefins are delivered by the time the reaction starts, and thereafter, raw materials are not delivered and reaction products are not taken out until the reaction is completed.
The distribution method refers to a method in which a part of the products, etc., is continuously transported in and out of the reactor during the reaction, and the distribution method is a method in which all raw materials and products are continuously transported in and out of the reactor during the reaction. It goes without saying that the reaction can be carried out continuously for a long period of time. In order to carry out the polymerization operation in a flow system in the method of the present invention, at least one group in each of the polymerization step (A), polymerization step (B), and polymerization step (C) is constantly reacted, and a total of at least three groups are reacted. Requires equipment. Of course, if such a reactor is used, the reaction can also be carried out in a semi-batch mode or a batch mode. Furthermore, the latter polymerization operation can also be carried out using two reactors.
That is, in both the polymerization step (A) and the polymerization step (B), one reactor is used each, and both polymerization operations are performed in either a semi-batch method or a batch method.
After selecting and carrying out the method, both reactors are interconnected to form substantially one reactor, and then the polymerization operation in the polymerization step (C) is carried out again in either the semi-batch method or the batch method. This is done by selecting a method. No matter which polymerization operation is selected, the operating methods in both the front and rear steps must be the same in principle. According to the method of the present invention, the reaction conditions of the latter polymerization step (C) are at an intermediate level compared to the reaction conditions of the earlier polymerization step (A) and the polymerization step (B). And when transferring the suspension of each reaction mixture in the first stage required to move from the polymerization step (B) to the subsequent polymerization step (C), the liquid is transferred without creating an excessive pressure difference in the opposite direction. Differential pressure or low head pumps are sufficient as means, and hydrogen in a new single reaction mixture obtained by mixing the reaction mixtures of the previous polymerization step (A) and polymerization step (B) is sufficient. Since the hydrogen concentration is approximately intermediate, it is enough to adjust the hydrogen concentration by adding a small amount of hydrogen or an inert solvent. The target polymer obtained by the method of the present invention can be separated and recovered from the reaction mixture still containing the polymer in the polymerization step (C) by a commonly used method. According to the method of the present invention, the latter polymerization step (C) produces an intermediate molecular weight product, the molecular weight of which is close to the average molecular weight of the target polymer, and the production ratio thereof is relatively low. Even if the control of the polymerization reaction in the polymerization step (C) changes slightly and the molecular weight and production amount of the intermediate molecular weight substance change slightly, their influence on the target polymer is reduced, and the control of the polymerization reaction in the polymerization step (A) and the polymerization step in the previous stage are reduced. In addition to being able to accurately and easily control the molecular weight and production amount of each high molecular weight polymer and low molecular weight polymer in step (B), it is also possible to accurately and easily control the average molecular weight and molecular weight distribution of the target polymer over a wide range. It has the advantage of being easy to perform. In addition, by increasing or decreasing the production ratio of intermediate molecular weight components, it is possible to maintain the uniformity of the target polymer. However, it also has the advantage of being able to be used without any particular restrictions. Furthermore, there is also the advantage that no special liquid transfer means or special vacuum hydrogen removal means are required when transferring the suspension of the reaction mixture, which is required to transfer from the former polymerization step to the latter polymerization step. When looking at the following examples, the uniformity of the polymer can be evaluated by the amount of gel generated in the molded product. In particular, when a non-uniform polymer is formed into a film, a large number of gels or fissures are generated, so the number of gels or fissures generated per film area can be compared. In addition, the molecular weight distribution of the polymer was evaluated by the ratio HLMI/MI value between the high load melt index (according to ASTM-D1238 condition F, expressed as HLMI) and the melt index (according to ASTM-D1238 condition E, expressed as MI). Ru. HLMI/MI
The larger the value, the broader the molecular weight distribution. EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples in any way. Example 1 (a) Catalyst production 3.7 g of metallic magnesium powder was placed in a 1000 ml flask equipped with a stirring device under a nitrogen atmosphere.
(0.15mol) and Ti(0-n-C ₄ H ₉ ) ₄ 102g
(0.3 mol) was added, the temperature was raised to 80℃, and 1.8
23.7 g of i-butanol with g of iodine dissolved in it
(0.32 mol) was added dropwise over 1 hour, then 120 mol
The reaction mixture was heated to ℃. After adding 400 ml of hexane to the reaction product thus obtained at room temperature, Al(C ₂ H ₅ ) diluted to 50 wt% with hexane
115 g (0.9 mol) of Cl ₂ was added dropwise at 45° C. for 2 hours to obtain a solid product. Hexane was added to this product, and the product was washed by a decanting method, that is, by repeating stirring, standing, and removing the supernatant until no chloride ions were detected in the supernatant. This solid product Ti
The content was 14wt%. (b) Polymerization Use two stirred reactors with an internal capacity of 5, charge 3 hexane into one reactor, and set the internal temperature to 85℃.
Triisobutylaluminum after adjusting to
1.7 g (8.5 mmol) and 262 mg of the solid catalyst obtained in (a) above were added. After adjusting the internal pressure of the autoclave to 1 Kg/cm ² with nitrogen gas, a hydrogen partial pressure of 19.0 Kg/cm ² was added, and then ethylene was added continuously to bring the total pressure to 25 Kg/cm ² . Polymerization was performed for minutes to produce a low molecular weight polymer. The other reactor was charged with 3 hexane and 1.7 g (8.8 mmol) of triisobutylaluminum.
And 120 mg of the solid catalyst obtained in (a) above was added.
After adjusting the internal temperature to 75℃ and the internal pressure to 1Kg/cm ² , a hydrogen partial pressure of 0.1Kg/cm ² was added, and the total pressure was further increased.
Ethylene was continuously added and polymerization was carried out for 65 minutes to obtain a high molecular weight polymer of 3.9 Kg/cm ² . Next, the reaction mixture containing these polymers was pumped into a stirred reactor with an internal volume of 10 through a connecting tube. After replacing the gas phase of this reactor with nitrogen, the internal temperature was set to 80°C and the internal pressure was set to 1.0Kg/ ^cm2 .
Add a hydrogen partial pressure of 1.2Kg/cm ² and further increase the total pressure to 5.2
Ethylene was continuously supplied at a concentration of Kg/cm ² , polymerization was carried out for 45 minutes, and the reaction mixture was filtered and dried to yield 2140 g of polymer. In addition, the amount produced at each stage is determined by the ethylene flow rate, and the production ratio is 40wt% for low molecular weight polymer in the first stage, 40wt% for high molecular weight polymer in the first stage, and 20wt% in the second stage.
It was hot. Furthermore, the obtained ethylene polymer powder was pelletized using an extruder with a screw diameter of 25 mmφ, and the MI of this pellet was 0.024.
HLMI/MI was 230 and density was 0.958. In addition, when this pellet was formed into a film using a balance film forming machine, the occurrence of fish eyes was small, and the number of fish eyes with a diameter of 0.2 mm or more was about 3000/m ² on a film with a thickness of 30 μm, and it was a good film. Summer. Comparative example 1 Hexane 6 was charged in a reactor with an internal volume of 10,
Triisobutylaluminum 3.4g (17m mol)
After charging 155 mg of the solid catalyst prepared in Example 1(a) and setting the temperature to 75°C and the internal pressure to 1.0 Kg/cm ² ,
Add a hydrogen partial pressure of 0.7Kg/ ^cm2 , and further increase the total pressure to 5.2Kg/cm2.
Continuously supply ethylene so that cm ²
Polymerization was carried out for 90 minutes. The yield of polyethylene was 1100g. MI was 0.08 and HLMI/MI was 30. Example 2 Polymerization was carried out in the same reactor as in Example 1(b) and in the same manner. The low molecular weight polymer in the first stage is heated to 85℃,
Polymerization was carried out for 60 minutes under the conditions of a hydrogen partial pressure of 19 kg/cm ² and an ethylene partial pressure of 5 kg/cm ² under 180 mg of the catalyst obtained in Example 1(a) and 1.7 g of triisobutylaluminum. The high molecular weight polymer was 75°C, hydrogen partial pressure 0.1 Kg/cm ² ethylene partial pressure 2.8 Kg/cm ² , and 120 mg of the catalyst obtained in Example 1(a).
and under 1.7g of triisobutylaluminum
Polymerization was carried out for 60 minutes. In the second stage, 80℃, hydrogen partial pressure 1.2
Polymerization was carried out for 50 minutes at a pressure of 3.0 Kg/cm ² and an ethylene partial pressure of 3.0 Kg/cm ² . The production ratio of each stage is 32% for low molecular weight polymer in the first stage, 32% for high molecular weight polymer in the second stage, and 36% in the second stage.
It was hot. The amount of polyethylene obtained was 2330 g, and the MI of the pellets obtained in the same manner as in Example 1(b) was
was 0.022, and HLMI/MI was 135. Also, the fixation of the film using these pellets is
It was 629 pieces/ ^m2 . Comparative Example 2 The polymerization carried out in Example 1 was carried out separately under the same conditions except for the hydrogen partial pressure, to obtain three types of polymers having different molecular weights. These three types of polymers were powder blended. The blend ratio was the same as in Example 1, with a high molecular weight polymer: 40 wt%, a low molecular weight polymer: 40 wt%, and an intermediate molecular weight polymer: 20 wt%.
This blend was pelletized. MI: 0.025,
The HLMI/MI was 209, but the number of fisheyes was extremely large at approximately 110,000 pieces/ ^m2 , and had no commercial value. Examples 3 to 7 Polymerization was carried out using the catalyst obtained in Example 1(a) in the same manner as in Example 1(b). Table 1 shows the polymerization conditions and results. In Examples 3 and 4, the production ratio of high molecular weight polymer: low molecular weight polymer: intermediate molecular weight polymer, respectively, was
44wt%: 44wt%: 12wt% and 38wt%: 38wt
%: The same conditions as in Example 1 were used except that the content was changed to 24 wt%. The results show that both MI and HLMI/MI have almost the same values as the polymer obtained in Example 1, and this degree of variation in the production ratio of the intermediate molecular weight product in the latter stage has almost no effect on the physical properties of the final polymer. This indicates that the In Example 5, the polymerization conditions for the high molecular weight polymer were as follows:
The same conditions as in Example 1 were used except that the amount of hydrogen was 14.6% by mole in the gas phase. As a result, MI: 0.43,
A polymer having a HLMI/MI of 61 and a weight of 135 pieces/m ² was obtained. Examples 6 and 7 were conducted under the same conditions as Example 5 except that the production ratio was changed. The results showed that, as mentioned above, variations in the intermediate molecular weight have almost no effect on the physical properties of the final polymer. In addition, in Example 7, although the production ratio of intermediate molecular weight substances was extremely low at 6 wt%, there were few fisheyes, and it can be said that this greatly contributed to the uniformity of the polymer.

[Table] Comparative example

Claims (1)

[Scope of Claims] 1. In the presence of a Ziegler-type catalyst improved to have high activity, an inert solvent, and a molecular weight regulator, at least one type of olefin is produced in several polymerization steps with different reaction conditions. In a method for producing a polyolefin with a wide molecular weight distribution, which involves controlling the average molecular weight and molecular weight distribution of a polymer over a wide range by introducing and polymerizing, first, in the presence of the same type of catalyst common to each polymerization step, A polymerization step (A) in which at least one type of olefin is introduced and polymerized to produce a relatively high molecular weight polymer under reaction conditions in which at least one of the concentration of a molecular weight regulator and the reaction temperature is kept at a low level; In the presence of a catalyst, at least one type of olefin is introduced and polymerized under reaction conditions in which at least one of the concentration of a molecular weight regulator and the reaction temperature is maintained at a high level to produce a relatively low molecular weight polymer. The reaction mixture containing the polymer in each of the above polymerization steps is then mixed to form a new single reaction mixture, and in the presence of ,
At least one of molecular weight regulator concentration and reaction temperature
At least one
In the polymerization step (C), different types of olefins are introduced and polymerized to produce a polymer with a molecular weight located in the center of the molecular weight of the polymer produced in each of the above polymerization steps, and the desired The production ratio of polymer in each polymerization step to polymerization step (A)
25 to 70 wt% in the polymerization step (B), 25 to 70 wt% in the polymerization step (B)
A polyolefin with a wide molecular weight distribution characterized in that the desired polymer is recovered from the reaction mixture containing the polymer in the polymerization step (C) as 70 wt% and 5 to 50 wt% in the polymerization step (C). manufacturing method. 2 Using hydrogen as a molecular weight regulator, the polymerization process
2. The production method according to claim 1, wherein polymerization is carried out under reaction conditions in which the hydrogen concentration in (A) is set to one-half or less of that in polymerization step (B). 3 The reaction temperature was set at 50 to 90°C in the polymerization step (A),
60-100℃ in polymerization step (B) and polymerization step (C)
The manufacturing method according to claim 1, wherein the polymerization is carried out under reaction conditions at a level of 50 to 100°C. 4. The manufacturing method according to claim 1, wherein at least one olefin selected from the group of ethylene, propylene, and 1-butene is polymerized. 5 In each step of the polymerization step (A), polymerization step (B), and polymerization step (C), one reactor was used each, and each polymerization operation was performed in a flow method, a semi-batch method, and a batch method. The manufacturing method according to claim 1, which is carried out by the method. 6 In both the polymerization step (A) and the polymerization step (B), use one reactor each, and after performing both polymerization operations in one method selected from semi-batch method and batch method, both reactors are interconnected to form substantially 1
2. The manufacturing method according to claim 1, wherein the polymerization operation in the polymerization step (C) is carried out in one method selected from a semi-batch method and a batch method.