JPH049804B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Technology] The present invention relates to a continuous process for producing a high melt viscoelastic polypropylene copolymer. More specifically, the present invention polymerizes propylene, ethylene, and a linear or branched α-olefin having 4 to 8 carbon atoms in multiple stages using three or more polymerization vessels connected in series, thereby achieving a wide molecular weight distribution. The present invention relates to the above method for producing a polypropylene copolymer suitable for post-processing sheets and blow molding. [Prior Art] General-purpose polypropylene has the following problems when used as sheets for post-processing. That is,
Sheets processed using polypropylene have the following problems during heat forming for post-processing (or secondary processing): the sheet sags quickly, the range of processing conditions is narrow, and the forming efficiency is low. inferior,
With wide sheets, the sagging is large, the thickness of the post-processed product tends to be uneven, and the sheet tends to accumulate and wrinkle. General-purpose polypropylene also has the following problems for blow molding applications. That is, the large sagging of the parison during molding results in uneven wall thickness of the molded product, and therefore the blow molding method can only be applied to the production of small molded products.
If high molecular weight polypropylene is used to prevent the above-mentioned sagging, it may result in poor fluidity, large load and energy loss during molding, the risk of mechanical trouble, and severe roughening of the molded product, resulting in loss of commercial value. Nawareru etc. In order to improve the above-mentioned sheet moldability and blow moldability when general-purpose polypropylene is used, the following techniques a to c have been proposed. In other words, a.
-8848 mixes polypropylene with low density polyethylene. However, molded products using such mixtures are prone to rough skin, and to prevent this, strong kneading is required when melting the mixture, which imposes restrictions on the selection of kneaders and power consumption. In addition, there is a problem that the rigidity of the molded product decreases. Next, b. JP-A-57-185336, JP-A-187337, JP-A-58-7439, etc. propose a method of mixing and kneading polypropylenes of different molecular weights using a granulator or the like. However, when the mixture obtained in this way is used, the surface of the molded product is more likely to become rough than when the aforementioned low-density polyethylene is mixed, and there are restrictions on the kneading method and the selection conditions of the molecular weight difference between the mixtures. be done. Furthermore, various methods have been proposed for expanding the molecular weight distribution of polypropylene by multi-stage polymerization of propylene in order to solve the problems caused by mixing methods such as c. a and b described above. For example, JP-A-57-185304, JP-A-19006, JP-A-58-7406,
In examples such as JP-A No. 7409 and JP-A No. 59-172507, a difference in molecular weight is imparted to polypropylene by performing the above-mentioned multi-stage polymerization operation in a batch polymerization method, but the batch polymerization method essentially There is a problem in that the productivity per capacity of the polymerization vessel is low because there is idle time during which the polymerization reaction is not performed, such as when charging raw materials and removing products. However, the above-mentioned invention by Croup also refers to the continuous method. To produce polypropylene with different molecular weights using a continuous method,
Depending on the order of manufacture, it is divided into two types. First, when producing in the combination order of high molecular weight and low molecular weight, this can be accomplished by simply adding hydrogen in the subsequent polymerization vessel, and although the operation is smooth, there are problems as described below. Second, when producing in the combination order of low molecular weight - high molecular weight, after producing the low molecular weight polypropylene in the first stage, to the reaction mixture,
It is stated that this method is inferior to the first case in terms of smoothness of operation, as it becomes necessary to remove excess hydrogen by operations such as drop-pressure degassing. The inventor of the present invention studied the first method of manufacturing in the combination order of high molecular weight and low molecular weight among the inventions in group c above, and found that the following problems existed. In other words, if the melt flow rate (hereinafter referred to as MFR) of the high molecular weight portion of the obtained polypropylene is low, it will be difficult to measure the MFR of the high molecular weight portion.
It becomes difficult to adjust the MFR by adjusting the operating conditions (Note: Although it is of course possible to measure the viscosity [η] of such polypropylene, it takes time to measure [η], and it is difficult to control the operation. (not appropriate). Furthermore, polypropylene produced in the order of high molecular weight - low molecular weight is
The difference in MFR value between the MFR value and the pellet after granulation is abnormally large (note: the MFR value of the powder is lower), so adjustment of the molecular weight range and adjustment of the MFR (granulated product) as a product for polypropylene Up,
It turned out there was a problem. On the other hand, in blow molding applications, transparency may be particularly required, and for this purpose, ethylene, ethylene, and other α-
Various improvement methods have been implemented, such as copolymerizing olefin (hereinafter referred to as α-olefin) with propylene, using additives such as nucleating agents, and combining the former two. In addition, as an improvement method using a processing method, polypropylene is stretched and oriented at a temperature lower than its melting point.
Axial stretch blow molding methods have also been implemented. By the way, in the copolymerization of ethylene or α-olefin with propylene, when the proportion of ethylene or α-olefin used is increased, there are problems in terms of productivity and economy. Further, in the above-mentioned biaxial stretching blow molding, there was a problem that the parison was easily deformed during the heating stage before stretching, and the temperature range suitable for processing was narrow. [Object of the Invention] As a result of various studies to solve the above-mentioned technical problems, the present inventors connected three or more polymerization vessels in series, supplied catalyst and hydrogen only to the first tank, and produced propylene and ethylene. When copolymerizing α-olefin and/or α-olefin, as the polymerization reaction mixture in the first tank is sequentially transferred to the subsequent polymerization vessels, the catalyst concentration and hydrogen concentration decrease in the successive subsequent polymerization vessels. The present invention was completed based on the knowledge that it is possible to produce a polymer with a higher molecular weight and that a polypropylene copolymer with a wide molecular weight distribution can be obtained as a final product. As is clear from the above description, an object of the present invention is to provide a method for continuously producing a highly melt viscoelastic polypropylene copolymer that has a wide molecular weight distribution and has good moldability, particularly with excellent operability and easy quality control. The objective is to provide an improved manufacturing method.
Another object is to provide a high melt viscoelastic polypropylene with excellent moldability produced by the above method. [Configuration and Effects of the Invention] The present invention has the following configuration. (1) Propylene and ethylene and/or linear or branched α-carbon atoms having 4 to 8 carbon atoms are produced by slurry polymerization or bulk polymerization using a Ziegler-Natsuta type catalyst.
In a method of continuously producing a polypropylene copolymer by copolymerizing olefins, A. Using three or more polymerization vessels connected in series, supplying the entire amount of the catalyst to be used to the first polymerization vessel, and is sequentially and continuously transferred to the second and subsequent polymerization vessels together with the reaction mixture, hydrogen is used as a molecular weight regulator, and the entire amount of hydrogen to be used is supplied to the first polymerization vessel,
The hydrogen is successively transferred to the second and subsequent polymerization vessels together with the reaction mixture, and the polypropylene copolymer produced in each polymerization vessel is sequentially formed on the catalyst, and then the reaction slurry is transferred from the last polymerization vessel. B is adjusted so that the polymerization amount Qi per unit time in the i-th polymerization vessel is within the range of the following formula (1), 0.70×Q _T /nQi1.30Q _T /n... (1) However, _o 〓 ⁱ⁼¹ Qi=Q _T =1 Note. Q _T : Total polymerization amount per unit time = 1.0 i: i-th polymerizer n: number of polymerizers C MFRi and MFRi, which are the MFR values of the polymers produced in the i-th and i+l-th polymerizers
+1 are adjusted so that they have the relationship shown in the following formula (2), logMFRi/MFRi+11.0...(2) D The polymerization pressure of the i-th polymerizer among the polymerizers connected in series is the i-1st It is adjusted so that the polymerization pressure of the i-th polymerizer among the polymerizers connected in series is not lower than the polymerization pressure of the i-1 polymerizer by more than 2 kg/cm ² G. Adjusted so that the temperature does not increase by more than 10°C, F using diethylaluminum chloride as the organoaluminum compound combined with the titanium-containing solid product constituting the Ziegler-Natsuta type catalyst and methyl paratoluate as the third component, G ethylene and or The content of ethylene and the linear or branched α-olefin having 4 to 8 carbon atoms in the polypropylene copolymer obtained by supplying the linear or branched α-olefin having 4 to 8 carbon atoms is within the range of the following formula (3). A continuous production method for a high melt viscoelastic polypropylene copolymer, characterized by the following. C ₂ % (i) C ₂ % (i + 1) C ₂ % (i +
2) ...(3) C ₂ % (i); Content of ethylene and/or linear or branched α-olefin having 4 to 8 carbon atoms in the polypropylene copolymer obtained in the i-th polymerization vessel Used in the present invention The catalyst is a so-called Ziegler catalyst, which is a combination of a transition metal compound and an organic compound or hydride of a group metal of the periodic table.
There is no particular restriction as long as it is a Natsuta type catalyst. However, it is preferable to use a catalyst that basically combines a titanium compound and an organoaluminum compound. The titanium compound is activated by further pulverizing titanium trichloride or a titanium trichloride composition obtained by reducing titanium tetrachloride with hydrogen or metal aluminum, etc. using a ball mill, vibration mill, etc.;
Alternatively, titanium trichloride obtained by further treating the above activated substance with an electron-donating compound, or by reducing titanium tetrachloride with an organoaluminum compound and undergoing various treatments (for example, by heating in TiCl ₄ to undergo crystal transition) composition, a titanium trichloride composition obtained by treating with an electron-donating compound and/or an electron-accepting compound to obtain a highly activated titanium trichloride composition, a carrier such as magnesium chloride, etc. Catalysts generally used for stereoregular polymerization of propylene can be used, such as a so-called supported catalyst obtained by supporting titanium tetrachloride. As the above-mentioned organoaluminum compound preferably used in the present invention, a compound represented by AlRnR'n'X _3-(o+o ' ₎ is particularly preferred. In the formula, X represents halogen of fluorine, chlorine, bromine and iodine,
n and n' represent arbitrary positive numbers satisfying 0<n+n'3. Specific examples include trialkylaluminums and dialkylaluminums, and two or more of these can also be used in combination. The above-mentioned catalyst may further be used in combination with an electron donor known as a so-called third component. Polymerization methods include slurry polymerization using the raw material propylene and a catalyst, as well as an inert solvent such as a hydrocarbon solvent such as propane, hexane, heptane, octane, benzene, or toluene, or bulk polymerization using propylene itself as a solvent (dispersion medium). Can be used. The polymerization vessels used in the method of the present invention are preferably three or more tank-type units connected in series, and the reaction mixture is transferred from a portion of the liquid phase (slurry) in the previous stage polymerization vessel. is continuously transferred to the next stage polymerization vessel. Three or more polymerizers must be connected in series. In the method of the invention, the entire amount of the catalyst is supplied only to the first tank. The catalyst (solid) is sequentially passed through the second and subsequent polymerization vessels together with the above-mentioned reaction mixture,
The polypropylene copolymer is formed sequentially in each polymerizer on the same catalyst solids, and the reaction mixture containing such catalyst solids is continuously withdrawn from the final vessel polymerizer. If a catalyst is added to any of the polymerization vessels after the second tank and polymerization is performed, a polymer with a significantly different MFR from that passed through the first tank will be formed on the additional catalyst particles. Even when the product is granulated after the product is obtained, it is not mixed uniformly, causing a defect in the appearance of processed products such as FE. In the method of the present invention, the entire amount of hydrogen used as a molecular weight regulator is supplied only to the first tank, similar to the above-mentioned catalyst. The hydrogen supply position within the polymerization vessel may be either a liquid phase portion or a gas phase portion. However, when supplying hydrogen to the liquid phase portion, care must be taken to prevent the supply from becoming entrained as bubbles in the slurry being withdrawn (transferred) to the second tank. This is because, in the method of the present invention, the hydrogen supplied to the second tank and subsequent tanks is generally supplied from the tank immediately preceding each tank only in a state dissolved in the reaction mixture (slurry). Therefore, when the hydrogen entrained as bubbles is sent to the next tank, the molecular weight difference between the polypropylene copolymer produced in that tank and the polypropylene copolymer produced in the next tank will be as expected. This is not preferable because the molecular weight distribution of the polypropylene copolymer as the final product cannot be sufficiently wide. Further, in the method of the present invention, three or more polymerization vessels connected in series are used. In the method of the present invention in which the catalyst and hydrogen are supplied only to the first tank, with two polymerization vessels, it is not possible to widen the polymerization degree distribution of the polypropylene product sufficiently to meet its intended use. Unlike the above-described method of supplying the catalyst and hydrogen, the raw material propylene or the solvent can be supplied in the required amount to each stage of the polymerization vessel. The amount of propylene copolymer polymerized in the polymerization vessel at each stage is determined by the following formula to maintain the quality of the final product.
It is desirable to keep it within the range shown in (1). 0.70×Q _T /nQi1.30Q _T /n ...(1) However, _o 〓 ⁱ⁼¹ Qi=Q _T =1 Note. Total polymerization amount Q _T = 1) i: i-th polymerization vessel Qi: i-th polymerization vessel n: number of polymerization vessels As shown in the above formula (1), the specific polymerization amount of each polymerization vessel is: It is necessary to adjust the amount within a range of ±30% based on the case of uniform polymerization in each polymerization vessel. If the Qi value is outside the range of formula (1) above, the molecular weight distribution of the final product will be insufficiently wide, making it difficult to obtain a high melt viscoelastic polypropylene copolymer of the desired quality. . Although the polymerization temperature of the method of the present invention is not limited,
Usually 20 to 100°C, preferably 40 to 80°C is easy to carry out. The temperature of each polymerization vessel may be the same or different. However, regarding the polymerization temperature, in the polymerization vessels connected in series, the temperature of the later polymerization vessel is higher than the polymerization temperature of the immediately preceding polymerization vessel.
It is necessary to prevent the temperature from rising more than 10℃. If the polymerization temperature of the latter stage polymerization vessel is higher than that of the former stage,
If the temperature is higher than 10°C, the molecular weight of the polypropylene produced in the latter stage will be too low, making it impossible to sufficiently widen the molecular weight distribution of the final product. On the contrary, there is no restriction on the difference in polymerization temperature between the polymerization vessels immediately before and after the polymerization vessel, as long as the temperature is the same or the temperature in the latter stage is lower than that in the former stage. This is because the method of the present invention is a method for producing polypropylene with a higher degree of polymerization in the later stages of the polymerization vessel. Therefore, in order to further widen the molecular weight distribution of the polypropylene according to the present invention, it is easier to raise the temperature of the first polymerization reactor to the highest level and gradually lower the temperatures of the second and subsequent polymerization reactors. The polymerization pressure of the method of the present invention is, but not limited to,
Normal pressure to 50 kg/cm ² G is usually used. The polymerization pressures of the polymerization vessels connected in series according to the method of the present invention may be the same or different. However, in the preceding and succeeding polymerization vessels connected in series, it is necessary to ensure that the polymerization pressure in the subsequent polymerization vessel is preferably not lower than the polymerization pressure of the immediately preceding polymerization vessel by more than 2 kg/cm ² . If it is lower than 2Kg/ ^cm2 , the molecular weight of the polypropylene copolymer produced in that polymerization vessel will be lower than the expected one,
It becomes difficult to widen the molecular weight distribution of the final product sufficiently. As is clear from the above explanation, in the method of the present invention, it is easier to control the molecular weight distribution of the final product more broadly by increasing the pressure in each polymerization vessel connected in series starting from the first tank. become. In the method of the present invention, the average residence time of the reaction mixture in each polymerization vessel connected in series is not limited, but is usually 30 minutes to 10 hours. Also,
The object of the present invention can be easily achieved by selecting and carrying out the various polymerization conditions described above, ie, pressure, temperature, residence time, etc., depending on the quality of the desired polypropylene copolymer, the catalyst used, etc. In addition, the slurry can be transferred between the polymerization vessels connected in series by conventional pump transportation, differential pressure transportation, or other methods without any particular limitations. The MFR of the polypropylene copolymer according to the present invention obtained as described above is usually 0.01 to 100, but especially for sheet molding and suction molding,
The MFR value used is 0.05 to 10, preferably 0.10 to 5.0. Incidentally, when expressed as an MFR value, the molecular weight difference between polypropylene copolymers produced in each polymerization reactor connected in series is preferably within the range of formula (2) below. logMFRi/MFR _i+1 1.0 ……(2) Then, MFRi; of the polymer produced in the i-th polymerization reactor.
MFR MFR _i+1 : MFR of the polymer produced in the i+1st polymerization reactor If the value on the left side of the above equation (2) is less than 1.0,
This is not preferable because the high melt viscoelasticity that is the objective of the present invention tends to be insufficient. Further, the upper limit of the numerical value is not limited, but it is difficult to set it to 3.0 or more in a specific embodiment of the method of the present invention. Ethylene and/or α-olefin is used as the monomer copolymerized with propylene. Ethylene is supplied in an amount of 1.0 to 10% by weight, preferably 2.0 to 7.0% by weight, based on propylene. i.e. 0.5-7.0
% by weight, preferably from 1.5 to 5.0% by weight, is copolymerized into the target copolymer. It is also possible to use α-olefin in addition to ethylene, such as using a combination of ethylene and α-olefin, using a mixed α-olefin, and using only a single α-olefin in combination with propylene. method is also possible. The α-olefin is a linear or branched α-olefin having 4 to 8 carbon atoms, specifically, for example, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 4-methylpentene. -1st grade is given. The feeding mode of ethylene and α-olefin is preferably within the range of the following formula (3) with respect to the melting point of the copolymer obtained in each polymerization vessel. C ⁼ ₂ (i)C ⁼ ₂ % (i+1)C ⁼ ₂ % (i+2) ...(3) C ⁼ ₂ (i), C ⁼ ₂ % (i+1), C ⁼ ₂ % (i+2): i, Ethylene content in the copolymers produced in the i+1 and i+2 stages: In other words, in the first tank, a copolymer that is closest to a propylene homopolymer is produced, and from the second tank onwards, the ethylene supply amount is increased sequentially to produce a copolymer with a high ethylene content. This is the way to obtain. The reason for carrying out such a polymerization method is as follows. That is, by widening the distribution of ethylene concentration, the appropriate processing temperature range during biaxial stretching can be widened. By obtaining a polymer close to a propylene homopolymer in the first tank (in the initial stage of polymerization), the shape of the polymer particles can be maintained well, and the operability of the plant can be improved. The higher the molecular weight, the smaller the amount of by-produced polymer soluble in the polymerization solvent, so it is advantageous to make a copolymer with a high ethylene content (large amount of soluble polymer produced) in the later stage where the molecular weight increases. It is. The main effects of the method of the present invention are summarized as follows. First, the polypropylene copolymer according to the method of the present invention has a wide molecular weight distribution, so it has good fluidity during extrusion molding, and has effects such as increasing the amount of extrusion by an extruder and saving power consumption. Furthermore, since it has characteristics such as excellent fluidity during injection molding, it can exhibit excellent effects in terms of quality and processing efficiency when used in various molding fields. Secondly, the method of the present invention is a multi-step polymerization method, and it is extremely easy to manage the polymerization process or adjust the polymerization conditions. That is, since the catalyst and hydrogen are supplied only to the first tank of three or more polymerization tanks connected in series, the necessary propylene, ethylene, α-olefin, and solvent can be added to the second tank and subsequent tanks. The polymerization conditions for each tank may most simply be the same pressure and temperature, but even if the pressure and temperature are reversed between two adjacent tanks (note: the later stage is numerically higher), the same pressure and temperature may be used. If the degree is within the permissible limit range (2 kg/cm ² G or less, 10° C. or less), the purpose of the present invention can be achieved. Although it will be explained in more detail below with examples,
The present invention is not limited to this. The following method was used to measure the physical property values according to the examples of the present invention. (1) Melt flow rate (MFR): ASTMD
1238 (2) Calculation of MFR of the polymer produced in each polymerization vessel: MFR ₁ ; MFR of the 1st stage (*1) MFR ₂ ; 2nd MFR ₃ ; 3rd MFR ₁₊₂ ; The whole generated in the second stage
MFR (*1) MFR ₁₊₂₊₃ ; Total MFR generated in the first, second, and third stages (*1) W ₁ ; Polymerization ratio of the first stage (*2) W ₂ ; 2nd (*2) W ₃ ; 3rd (*2) W ₁ +W ₂ +W ₃ =1.0 *1; Sampling and actual measurement at each stage. *2; Sampling was carried out at each stage, the titanium content in the polymer (fluorescent X-ray analysis) was measured, and the polymerization ratio was determined by calculation. MR ₂ and MFR ₃ were calculated using the following relational expressions. logMFR ₁₊₂ = (W ₁ /W ₁ +W ₂ )logMFR ₁ + (W ₁ /W ₁ +W ₂ )logMFR ₂ logMFR ₁₊₂₊₃ = (W ₁ +W ₂ /W ₁ +W ₂ +W ₃ )logMFR _{1 +2} + (W ₃ /W ₁ +W ₂ +W ₃ )logMFR ₃ (3) Ethylene content (WT%): Infrared absorption spectroscopy (difference spectroscopy for polymerizers 2 and 3) (3') 1-Butene, 1 -Hexene content: Same as above (4) Method for measuring physical properties of sheet molded products: Heating behavior; Chitsuso method In order to evaluate the heating vacuum formability of the sheet using a model, the sheet was fixed in a 40 cm x 40 cm frame.
It was placed in a constant temperature room at 200°C and the following physical properties were measured.
That is, (a) sheet drooping amount (mm), (b) maximum return amount (Note: {1/150 x (150 - maximum recovery drooping amount (mm) x 100}), and (c) maximum recovery amount. (5) Sheet appearance: Visual observation (6) Biaxial stretchability A JIS No. 2 tensile test piece (2 mm thick) was injection molded, and Autograph IS-500 (Shimadzu Seisakusho Co., Ltd.)
A tensile test was conducted in a hot air circulation type constant temperature bath. (Tension speed 50mm/min, distance between chucks
10mm). Γ Stretching temperature range (℃): Temperature at which the yield point cooperation (A) and the minimum strength after the yield point (B) become B/A = 1 (T ₂ )
The difference in temperature (ΔT) at which the tensile test piece deforms under no load was determined. The larger ΔT is, the better the biaxial stretchability is. (7) Transparency: After stretching at a temperature of B/A=1 in (6), the test piece was evaluated visually. ○: Transparent, △: Transparent with a whitish appearance, ×: Translucent (8) Soluble polymer (wt%) After polymerization, the ratio of polymerization solvent-soluble polymer (a) to polymerization solvent-insoluble polymer (b) was determined. demand. Soluble polymer = a / a + b × 100 Example 1 (1) Production of catalyst 6 n-hexane, 5.0 mol of diethylaluminum monochloride (DEAC), and 12.0 mol of diisoamyl ether were mixed at 25°C for 5 minutes.
The mixture was allowed to react for 1 minute at the same temperature to obtain a reaction solution (2.4 molar ratio of diisoamyl ether/DEAC).
40 mol of titanium tetrachloride was placed in a reactor purged with nitrogen and heated to 35°C, and the entire amount of the reaction product solution () was added dropwise to this over 180 minutes, and then heated to the same temperature.
The reaction was kept for 30 minutes, heated to 75°C, reacted for an additional hour, cooled to room temperature, removed the supernatant, added 30% n-hexane, and removed by decantation, which was repeated 4 times to obtain a solid product ( ) Obtained 1.9Kg. The entire amount of this () was suspended in n-hexane 30°C and diisoamyl ether was added at 20°C.
1.6 kg and 3.5 kg of titanium tetrachloride were added at room temperature for about 5 minutes, and the mixture was reacted at 65°C for 1 hour. After the reaction is complete, cool to room temperature (20°C), remove the supernatant by decantation, add 30% n-hexane, stir for 15 minutes, leave to stand, and remove the supernatant. After repeating 5 times, dry under reduced pressure,
A solid product () was obtained. (2) Preparation of catalyst Charge 40 g of n-hexane, 850 g of diethylaluminium chloride, 360 g of the above solid product, and 3.8 g of methyl paratoluate into a tank with an internal volume of 50, then add propylene gas while maintaining the temperature at 30°C with stirring. Pretreatment was carried out by feeding at 180 g/H for 2 hours. (3) Polymerization method The polymerization was carried out using the polymerization apparatus shown in the figure. N-hexane 26/H and catalyst slurry 120 ml/H were continuously supplied to the polymerization vessel 1 every hour. The temperature of polymerization vessels 1 to 3 is 60℃, and the pressure is 6Kg/each.
cm ² G, 8 Kg/cm ² G, and 10 Kg/cm ² G were supplied with hepropylene to each polymerization vessel. When the hydrogen concentration in the gas phase of polymerizers 1 to 3 (each 150) was supplied so that only polymerizer 1 had a hydrogen concentration of 8.1 mol%, the hydrogen concentration in the gas phase of polymerizers 2 and 3 was 1.2 mol%, respectively. It was 0.14 mol%.
The amounts of ethylene supplied to polymerization vessels 1 to 3 were 25 g/H, 90 g/H, and 180 g/H, respectively. The analytical values of the reaction amount, MFR, and ethylene content in each polymerization vessel are as shown in the table. The liquid level in each polymerization vessel was drawn out using a control valve so that the level was 80%. After the slurry extracted from the polymerization vessel 3 is depressurized by the degassing tank 4, it is subjected to catalyst deactivation treatment with methanol, neutralization with caustic soda water, further washing and separation with water, and drying process to obtain a white copolymer powder. It was obtained in an amount of 6Kg/H. (4) Granulation Add BHT to 15Kg of the white copolymer powder obtained above.
(2.6-di-t-ButyL-P-cresol) 15g,
Irganox1010 (Tetrakis〔Methylene (3.5−di
-t-butyL-4-Hydrocinnamate)]
methane) and 30 g of Calcium stearate were added and granulated using a 40 mmφ granulator. (5) Forming of sheet The granules were processed at 225°C using a 50 mmφ extrusion molding machine to produce a sheet with a width of 60 cm and a thickness of 0.4 mm.
The heating behavior of the sheet was measured by the method described above. (6) Preparation of tensile test piece The granulated product was prepared using an injection molding machine at a resin temperature of 230°C and a mold temperature of 50°C, and conditioned for 72 hours in a room with a humidity of 50% and a room temperature of 23°C. The sheet in (5) above was also adjusted in the same manner. Comparative Example 1 In Example 1, hydrogen was supplied to each polymerization vessel so that the hydrogen concentration in the gas phase of each polymerization vessel was made the same. In this case, the heating behavior of the sheet was poor. Comparative Examples 2 and 3 In Example 1, the third stage polymerization was omitted and the polymerization pressure and hydrogen concentration were varied as shown in the table. The amount of ethylene supplied was also 50 g/H in the first stage and 160 g/H in the second stage.
In this case as well, the heating behavior of the sheet was inferior to Example 1. Examples 2, 3, and 4 Example 1 was carried out by changing the polymerization pressure, polymerization temperature, and hydrogen concentration in the first stage as shown in the table. In addition, the amount of ethylene to be supplied was revised based on the analysis values, aiming for an ethylene concentration of 0.6%/4.0%/6.5% for the 1st stage/2nd stage/3rd stage. The results are shown in the table. Comparative Example 4 Example 1 was carried out by changing the pressure as shown in the table. In order to adjust the polymerization ratio in each polymerization vessel to the range of the present invention, the liquid level in the polymerization vessels was set to 40%, 60%, and 80% in polymerization vessels 1 to 3, respectively. In addition, the amount of ethylene supplied to polymerization vessels 1 to 3 is 15 g/H/
It was carried out at 60g/H/80g/H. When the pressure was outside the range of the present invention, it was difficult to maintain a sufficient MFR difference between polymerization vessels, and the heating behavior of the sheet was poor. Comparative Examples 5 and 6 In Example 1, experiments were carried out under the conditions shown in the table in order to change the polymerization ratio in each polymerization vessel. Comparative example 5,
The amount of ethylene supplied to polymerizers 1 to 3 in No. 6 is as follows:
26g/H/115g/H/115g/H and 10g/H/
It was 100g/H/200g/H. If the polymerization ratio is outside the range of the present invention, the heating behavior of the sheet will not be sufficiently improved. The reason why the heating behavior of Comparative Example 6 is good is because the pellet MFR is low.
need to be taken into consideration when comparing. Comparative Example 7 In Example 1, the catalyst slurry was distributed and supplied to each of the three polymerization vessels. The distribution ratio is 80%, 10%, and 10% in polymerizers 1 to 3, respectively.
And so. Regarding sheet properties, severe roughening (FE) occurred on the sheet surface. Comparative Example 8 In Example 1, the polymerization temperature and pressure conditions were changed as shown in the table. In order to adjust the polymerization ratio, the liquid levels in the polymerization vessels were set to 85%/65%/45% in polymerization vessels 1 to 3, respectively. Also, the ethylene supply amount is 12g/H/52g/H/95g/H, respectively.
And so. When the temperature difference between the polymerization vessels was set outside the range of the present invention, it became difficult to measure the MFR difference between the polymerization vessels, resulting in a significantly inferior heating behavior of the sheet. Comparative Example 9 In Example 1, the amount of ethylene supplied to each polymerization vessel was 115 g/H/115 for polymerization vessels 1 to 3, respectively.
g/H/115 g/H. Compared to Example 1, this is unfavorable because the amount of soluble polymer is large and the biaxial stretchability ΔT is small. Examples 5 and 6 In Example 1, the amount of ethylene supplied to polymerization vessels 1 to 3 was set to 10 g/H/50 in Examples 5 and 6, respectively.
g/H/90g/H and 10g/H/80g/H/140
g/H. The results were as shown in the table. Comparative Example 10 In Example 1, the amount of ethylene supplied to polymerizers 1 to 3 was 5 g/H/10 g/H/20 g/
It was carried out at H. It was inferior in terms of biaxial stretchability ΔT and transparency. Comparative Example 11 In Example 1, the amount of ethylene supplied to each polymerization vessel was 70 g/H/170 for polymerization vessels 1 to 3, respectively.
g/H/250g/H. The amount of soluble polymer produced increased with the increase in the amount of ethylene supplied. Comparative Example 12 In Example 1, the amount of ethylene supplied to polymerization vessels 1 to 3 was 220 g/H/110 g/H/15
g/H. When the ethylene supply amount is changed in the order of 1st stage > 2nd stage > 3rd stage polymerization vessel,
This is not preferable because the amount of soluble polymer produced increases significantly. Example 7 In Example 1, the amount of ethylene supplied to each polymerizer was set to 0 g/H/50 for polymerizers 1 to 3, respectively.
g/H/140g/H. Also, to polymerization vessel 1 1
- Butene was fed at 500 g/h. Polymerization vessel 1-3
The 1-butene contents in the sampled copolymers were 2.6 wt%, 2.0 wt%, and 1.5 wt%. Example 8 In Example 7, 1-butene was replaced with 1-butene.
Hexene was supplied to the polymerization vessel 1 at a rate of 500 g/H. The contents of 1-hexene in the copolymers sampled in polymerization vessels 1 to 3 were 1.4wt%, 1.0wt%,
It was 0.8wt%.

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【table】 [Brief explanation of drawings]

The figure is a flow sheet of a polymerization apparatus used to carry out the method of the present invention. In the figure, 1, 2, 3... polymerization vessel, 4... degassing tank, 5... pump.

Claims (1)

[Claims] 1 A polypropylene copolymer is obtained by copolymerizing propylene with ethylene and/or a linear or branched α-olefin having 4 to 8 carbon atoms by a slurry polymerization method or a bulk polymerization method using a Ziegler-Natsuta type catalyst. In a continuous production method, A. Three or more polymerization vessels connected in series are used, the entire amount of the catalyst used is supplied to the first polymerization vessel, and the catalyst is transferred together with the reaction mixture to the second and subsequent polymerization vessels. Hydrogen is used as a molecular weight regulator, the entire amount of hydrogen to be used is supplied to the first polymerization vessel, and the hydrogen is sequentially and continuously transferred to the second and subsequent polymerization vessels together with the reaction mixture. After sequentially forming the polypropylene copolymer produced by polymerization in each polymerization vessel on the catalyst, the reaction slurry is continuously discharged from the last polymerization vessel, and B the unit time in the i-th polymerization vessel. Adjust so that the polymerization amount Qi per unit is within the range of formula (1) below, 0.70×Q _T /nQi1.30Q _T /n ...(1) However, _o 〓 ⁱ⁼¹ Qi=Q _T = 1 Note ．． Q _T : Total polymerization amount per unit time = 1.0 i: i-th polymerizer n: number of polymerizers C MFRi and MFRi+1, which are the MFR values of the polymers produced in the i-th and i+l-th polymerizers
are adjusted so that they have the relationship shown in the following formula (2), logMFRi/MFRi+11.0...(2) D The polymerization pressure of the i-th polymerizer among the polymerizers connected in series is It is adjusted so that the polymerization pressure of the polymerization vessel is not lower than 2 kg/cm ² G, and the polymerization temperature of the i-th polymerization vessel among the polymerization vessels connected in series is 10% lower than the polymerization temperature of the i-1th polymerization vessel. temperature is controlled so that the temperature does not rise above ℃, F. Diethylaluminum chloride is used as the organoaluminum compound combined with the titanium-containing solid product constituting the Ziegler-Natsuta type catalyst, and methyl paratoluate is used as the third component, G. Ethylene and/or carbon The content of ethylene and/or linear or branched α-olefin having 4 to 8 carbon atoms in the polypropylene copolymer obtained by supplying the linear or branched α-olefin having 4 to 8 carbon atoms is within the range of the following formula (3). A continuous production method for a high melt viscoelastic polypropylene copolymer, characterized by the following. C ⁼ ₂ %(i)C ⁼ ₂ %(i+1)C ⁼ ₂ %(i+2)
...(3) C ₂ % (i); content of ethylene and/or linear or branched α-olefin having 4 to 8 carbon atoms in the polypropylene copolymer obtained in the i-th polymerization vessel