JPS5811519A - Preparation of block copolymer from propylene - Google Patents

Abstract

PURPOSE:To obtain the titled copolymer having well balanced physical properties between impact resistance, rigidity, etc., by polymerizing ethylene/propylene batchwise under conditions controlled to give a specific catalytic activity. CONSTITUTION:Polymerization of ethylene/propylene is carried out continuously at a reaction ratio between ethylene and propylene <=(6/94)wt% and batchwise at a reaction ratio between ethylene and propylene of (15/85)-(95/5)wt% by the multi-stage polymerizing method in plural connected polymerizers in the presence of a stereoregular catalyst. A catalytic activity reducing agent is added to a slurry in transferring the slurry to the polymerizers to reduce the catalytic activity to (1/4) or less, and the batchwise polymerization is started after transferring the slurry. In the process, an organoaluminum compound is added to improve the activity to 1.1 times that before the addition of the organoaluminum compound and carry out the batchwise polymerization. After the completion of the batchwise polymerization, the slurry is transferred to a zone for deactivating the polymerization activity of the slurry in a time of (1/3) or less the polymerization time in the batchwise polymerizers to afford the aimed copolymer.

Description

[Detailed Description of the Invention] The present invention provides “the most favorable variation among physical properties such as impact resistance and rigidity”.
The present invention relates to a method for producing a propylene-ethylene block copolymer having a high carbon content.

Since the invention of stereoregular catalysts by Ziegler and Natsuta et al., crystalline polystyrene has been used as a general-purpose resin with excellent rigidity, heat resistance, and lightweight molded products, and its production volume has increased in recent years. is increasing worldwide. However, crystalline polypropylene has the disadvantage of being brittle at low temperatures, making it difficult to use in applications requiring impact resistance at low temperatures.

A lot of research has already been done on how to improve this shortcoming.
Developments have been made and various improved methods have been proposed. Among them, a method of block copolymerizing propylene and other olefins 41 with ethylene is, for example, an industrially useful method.
It has been proposed in Tokuko Sho 3B-14834, 49th Kai Sho 39-1836, Tokko @39-15535, etc. However, compared to crystalline polypropylene, the nine-block copolymers produced by these methods have lower rigidity and transparency, and when deformed by impact or folding, the deformed parts turn white. have To solve these problems, a method of conducting block copolymerization in three stages was developed in 1973.
0621, Japanese Patent Publication No. 49-24593, etc., and the obtained block copolymers have very excellent physical properties.

On the other hand, there is a method of continuous production of phlohylene-ethylene block copolymer in order to improve the per unit volume of the polymerization tank per unit time and to obtain a large quantity of products with as uniform physical properties as possible. desired. However, even if the process yields a propylene-ethylene block copolymer with an excellent balance of physical properties in a batchwise manner, there are many problems in applying it to a continuous process. In order to obtain a block copolymer having the physical properties encountered in a continuous process, it is often necessary to provide several polymerization stages with different ethylene/propylene reaction ratios, and therefore it is necessary to prepare nine polymerization tanks for each stage. be. Furthermore, when multiple polymerization tanks are connected in series and polymerization is performed continuously, the residence time of the catalyst varies depending on each polymerization tank in a polymerization tank equipped with a complete mixing tank. Therefore, the distribution of the amount of polymerized catalyst is affected. Because of this, the physical properties of the produced polymers are very different between the continuous method and the batch method, and the former generally shows a drop in impact resistance O compared to the batch method.

As one method to solve these problems, in a method for producing ethylene-propylene pro//copolymer in which the polymerization of propylene alone or propylene-rich ethylene/propylene accounts for the majority of the total polymerization amount, the above-mentioned propylene alone or propylene One possible method is to perform a rich ethylene/propylene polymerization step continuously, and then perform several polymerization steps batchwise while changing the ethylene/propylene reaction ratio. A block copolymer with excellent balance of physical properties can be obtained using a polymerization tank of However, during the transfer of the slurry from the continuous polymerization stage to the batch polymerization stage, from the batch polymerization stage to the deactivation stage, and during the adjustment of hydrogen concentration, etc., unplanned and uncontrollable polymerization occurs. The balance of physical properties deteriorates. By transferring the slurry from the continuous polymerization stage to the batch polymerization stage in a short time using a large capacity pump or using a pressure difference, and by adjusting the hydrogen concentration by increasing the purge amount, Unplanned and uncontrollable polymerization.9
can be reduced. However, rapid discharge of slurry from the continuous polymerization tank will cause a sudden change in the level of the polymerization tank in which continuous polymerization is being carried out, making it difficult to control the temperature of continuous polymerization and the molecular weight of the produced polymer. Problems such as this arise. Furthermore, if a pump is used to transfer the slurry, a pump with a large capacity is required, which increases equipment costs. On the other hand, the slurry is rapidly transferred from the batch polymerization tank to the deactivation process without affecting the continuous polymerization reaction zone, and the pressure in the deactivation process is kept at a level lower than the pressure in the batch polymerization tank. Alternatively, it is also possible to install the batch polymerization tank at a higher position than the deactivation step and rapidly transfer the slurry to the deactivation step. In addition, the influence on the deactivation process can be avoided by setting the reaction conditions of the deactivation process close to the reaction conditions 6 in a batch polymerization tank to avoid the influence of rapid slurry discharge.

The purpose of the present invention is to produce a propylene-ethylene block copolymer having excellent physical properties such as impact resistance and high rigidity without any difficulty in controlling the polymerization process, and to obtain better properties than in the case of batch polymerization. It is an object of the present invention to provide a method for increasing productivity per unit time per unit volume of a polymerization tank without substantially deteriorating the physical properties of a polymer produced.

In the present invention, polymerization is carried out in a continuous manner in which the reaction ratio of ethylene/propylene is 6794 weight x or less during multi-stage polymerization in which two or more types of polymerization vessels are connected using a stereoregular catalyst. is 15/85~9515 weight
In a method for producing a propylene-ethylene block copolymer by batchwise polymerization, if a catalyst activity reducing agent is added to the KM slurry at the same time as or before the slurry is transferred to a polymerization tank for batch polymerization. and K to reduce the catalyst activity to 1/4 or less of the catalyst activity without adding the reducing agent, and then transfer the slurry to a polymerization tank where batch polymerization is carried out. After completion of the transfer, an organoaluminum compound is added when starting batch polymerization. By doing so, batch polymerization is performed under conditions where the activity is increased to 1.1 times or more the activity before adding the organoaluminum, and then, after the batch polymerization is completed, an operation is performed to deactivate the polymerization activity of the slurry. The present invention relates to a method for producing an ethylene-propylene block copolymer, which is characterized in that the slurry is transferred to the zone in the batch polymerization tank in a time that is ⅓ or less of the predetermined polymerization time.

The stereoregular catalyst used in the present invention is not particularly limited as long as it is a catalyst generally used for stereoregular polymerization of propylene. , ←) A catalyst consisting of an organoaluminum compound is preferred. A solid catalyst containing at least the three elements of hardness, π, and α can be produced by various methods.
-116079, JP-A-55-102606, and the like. Specifically, magnesium halides (for example, anhydrous dioxyalpha) and various organic compounds, such as aromatic orthocarboxylic esters, alkoxysilicon and halogenated hydrocarbons, orthocarboxylic esters and halogenated hydrocarbons, or Carboxylic acid ester and α.

A solid catalyst can be obtained by co-pulverizing the complex with alcohol and heat-treating the complex with 710 titanium oxide. Alternatively, by reacting an organomagnesium compound soluble in an inert solvent with various 710 genating agents, a solid polymer containing α and α which is insoluble in an inert solvent is synthesized, and further an electron-donating compound, It can also be obtained by treatment with titanium /S rogonide.

The organic aluminum ζ compound (fo) which is one of the components of the catalyst has the general formula Mnx, -m (wherein: R has 1 to 1 carbon atoms)
2 hydrocarbon residue, X is)-Rogge/atom, and 1≦m≦
Organic nicum represented by 3), 17-II-hexylaluminum, diethylaluminium monochloride, etc. can be used alone or in combination of two or more.

In addition, when the catalyst system KC-0 or a compound having at least one C--N bond is used in combination, the stereoregularity of the resulting polymer is increased and the physical properties are well-balanced. As the compound having at least one C-〇 or C-N bond, esters, ethers, orthoesters, alkoxy silicones, amines, amides, phosphoric acid esters, etc. are used, and more specifically, ethyl benzoate, toluic acid, etc. Methyl, methyl orthobenzoate, tetraethoxysilane,
Phenyltriethoxycran, dibutyl ether, triethylamide, diethylaniline, triethyl phosphate, etc. are preferably used.

The proportion of each component constituting the catalyst used in the present invention is arbitrary and the appropriate range varies depending on the compound used, but in general, the organoaluminide is 0.1 to 500 mol, and c-o
Or the compound having at least one C-N bond is 0 to 2
The range is 50 moles.

In the method of the present invention, using a polymerization tank in which two or more tanks are connected, 80X or more of the following polymerization is carried out continuously until the reaction ratio of ethylene/propylene is 6794 weight, and the specific reaction force of ethylene/propylene is 15/85 to 9515. Heavy 110 polymerization (
When 090X or more is carried out batchwise, an ethylene-propylene block copolymer is produced from K. Polymerization in which the reaction ratio of ethylene/propylene is 6/94 by weight or less also includes, of course, polymerization of propylene alone. Polymerization at the reaction ratio can also be carried out in the presence of an inert solvent, or by bulk polymerization using propylene itself as a solvent in the absence of a substantial inert solvent, or by gas phase polymerization in the substantial absence of a liquid polymerization solvent. . Ethylene/propylene reaction ratio is 6/9
Polymerization of ethylene/propylene at a weight of 4 weight or less is necessary to maintain a good balance between impact resistance and rigidity of the typical rubber polymer.
It is desirable that the weight of the ethylene-propylene block copolymer be 95% by weight or less. The polymerization temperature at the above reaction ratio varies depending on the catalyst system, but is generally 40 to 9
0°C, especially 60 to 80°C is preferred.

Further, in order to increase productivity, it is preferable to carry out the polymerization step at the above reaction ratio as continuously as possible.

Next, the reaction ratio of ethylene/propylene is 15/85 to 9
In order to obtain a polymerization step beak of 515 weight by weight, K is an essential step in order to obtain a combination of nine propylene-ethylene blocks with excellent impact resistance.The polymerization is carried out in the presence of an inert solvent or in the presence of an inert solvent. Bulk polymerization using propylene itself, which is not present in the solvent, as a solvent, or gas phase polymerization, in which a liquid polymerization solvent is not substantially present, can also be carried out.

The above polymerization temperature varies depending on the reaction ratio of ethylene/propylene, etc., but is generally 30 to 70°C, particularly preferably 40 to 60°C.

In the method of the present invention, a catalyst activity reducing agent is added to the slurry at the same time or before the slurry is transferred to a polymerization tank for batch polymerization, thereby reducing the catalyst activity to 174 or less compared to when the reducing agent is not added. , conditions in which the activity is increased to 1.1 times or more the activity before adding the organoaluminum compound by adding an organoaluminum compound when starting the batch polymerization after transferring the slurry to a polymerization tank where batch polymerization is carried out. Batch polymerization is carried out in the tank below, and then, after the batch polymerization is completed, the slurry is transferred to a zone where the polymerization activity of the thriller is deactivated in a time of 1/3 or less of the predetermined polymerization time in the batch polymerization tank. It is characterized by

During the transfer of the slurry from continuous polymerization to the batch polymerization process, from the batch polymerization process to the deactivation process, and while adjusting the degree of hydrogen immersion in the gas phase, uncontrollable polymerization occurs without a pre-chamber. The balance of physical properties of the resulting polymer becomes extremely unbalanced. Therefore, in order to reduce the unplanned and uncontrollable polymerization amount as much as possible, an activity reducing agent is added when or before transferring the slurry to the batch polymerization tank to reduce the catalyst activity in the polymerization tank to 174% or less of the original activity. Preferably 1/4
~1/IOK decrease. If it is larger than 1/4, the effect of reducing the amount of polymerization that cannot be controlled becomes smaller, while if it is larger than 1/10
If the temperature decreases, the amount of organoaluminum compounds added to restore activity will increase.

After the transfer of the slurry to the batch polymerization vessel is completed, an organoaluminum compound is added to restore appropriate catalyst activity, which is determined by the batch polymerization time and polymerization amount. The proportion of organoaluminum to be used depends somewhat on the type and amount of the activity-lowering agent, but it should be in an amount that increases the activity by at least 1 times the activity i before adding the organoaluminum compound, preferably 1 to 10 times the activity L. It is.

Next, at the same time as the predetermined polymerization in the batch polymerization tank is completed, the catalyst is deactivated within ⅓ or less of the predetermined polymerization time in the batch polymerization tank. The operation is generally carried out by transferring a slurry from a batch of heavy metal species to a zone containing a deactivator. By reducing the time required for transfer to 1/3 or less of the predetermined polymerization time in the batch polymerization tank, uncontrolled polymerization during transfer can be made substantially negligible. The shorter the time required for transfer, the less uncontrolled polymerization, which is preferable, but by setting it to 1/3 or less of the polymerization time, the influence of uncontrolled polymerization during transfer can be substantially avoided.

The activity reducing agent may be used as long as it reduces the catalyst activity, and various organic compounds and M ct8 ,
StC/4 negative inorganic compounds are used, but those that reduce the activity without reducing the stereoregularity of the produced polymer are preferred, and in particular those that reduce the activity without reducing the stereoregularity are preferred. It is preferable to use a compound whose activity can be restored by adding a small amount of an organoaluminum compound. For example, C-0 or C used as a preferred component of the catalyst system described above.
Compounds having at least one -N deposit are indicated. A specific example of the compound is Toosho mentioned above.

Further, as the organoaluminum compound used to restore the activity, the nine organoaluminum compounds used as one component of the catalyst system described above are preferably used.

By using the method of the present invention, it is possible to efficiently provide a glopyrene-ethylene block copolymer with an excellent balance of impact resistance and rigidity under controlled conditions, which is of great industrial significance.

The present invention will be explained in more detail with reference to Examples below. In the Examples and Comparative Examples, melt flow index (hereinafter abbreviated as MI) STM 01238 Bending rigidity 11j A8TM D747-63
Izot (with notch) M8TM 0256-56 Dupont M based on JIS K6718
I was measured at 230°C and a load of 2.16Kt, bending rigidity was measured at 20°C, and Izod and DuPont impact strengths were measured at 20°C and -10°C, respectively.

The intrinsic viscosity number (hereinafter abbreviated as Da) was measured at 135°C using a tetralin solution. The eye contact index (hereinafter abbreviated as ■) has been calculated.

Example 1 (1) Preparation of solid catalyst component A vibratory mill equipped with four grinding pots each having an internal volume of 4 L each containing 91 cf of steel balls with a diameter of 12 cm was prepared. To each pot were added 300 f of magnesium chloride, 77 runs of tetraethylene, 60 sd, α, α, d-)9 chlorotoluene 45-, and the mixture was ground for 40 hours. In an autoclave with an internal volume of 50 tons, add 3 fine particles of the above pulverized material and 201 pieces of titanium tetrachloride, stir at 80°C for 2 hours, remove the supernatant liquid by postmortem decantation, then add 35 tons of n-hepta and stir at 80°C for 15 minutes. After that, the washing operation of removing the supernatant liquid with Deka/Cheeseon was repeated 7 times, and then 20 tons of n-hebutane was added to prepare a solid catalyst slurry. When a part of the solid catalyst slurry was sampled, n-hebutane was evaporated and analyzed, it was found that the solid catalyst contained 1.4% by weight of n.

(II) Polymerization Polymerization is carried out using the polymerization apparatus shown in FIG. Into a 50 t autoclave which had been thoroughly dried and purged with nitrogen, 30 L of n-hebutane, 50 t of the above solid catalyst, 240 d of diethylaluminum chloride, and 140 ml of methyl p-toluate were placed and stirred at 25°C. This mixture is used as a catalyst slurry mixture. An autoclave with an internal volume of 300 L which has been sufficiently dried and purged with nitrogen and further with propylene gas is connected in series, and autoclaves C1 and C2 with an internal volume of 200 L are connected next to autoclave B in parallel. An autoclave D having an internal volume of 300 tons is connected in series to autoclaves C1 and C2. Charge autoclaves A and 1 with 60-propylene. The above catalyst slurry mixture as a solid catalyst was charged to the autoclave at a rate of 19/b, triethylaluminum at a rate of 1.5 L/b, and liquid propylene at a rate of 3011/h. Autoclave B was continuously charged with triethylaluminum at a rate of 30 m/h and polypropylene slurry from the autoclave at a rate of 3011 t/h.
Hydrogen was charged so as to maintain the gas phase hydrogen concentration of the autoclave and B at the amount shown in Table IK while continuously withdrawing it at 04/2, and polymerization was carried out at 75 °C, and 6 hours after the start of polymerization, the polymerization became stable. At the end of the day, a small amount of slurry was extracted from autoclave B and the physical properties of the powder were measured. Next, the slurry being continuously extracted from the lower part of autoclave B and methyl p-toluate were simultaneously charged into autoclave C1 at a speed of 1.4 m/30 cm, and after the slurry was placed in C1 for 30 minutes, The slurry from autoclave B and methyl p-) were transferred to autoclave C2. In C1, while receiving the slurry, liquid propylene 5- was injected under pressure while purging the gas phase, and at the same time the internal temperature was raised to 50°C, and at the same time, the hydrogen am was set to 0.3 M OIX. The activity during this time was reduced to 115 by the addition of p-doluic acid. Furthermore, ethylene and hydrogen are charged to reduce the hydrogen concentration in the gas phase to 0.55.
Mao! Then, the concentration of ethylene was adjusted to 35.0 mol%. 3. additional triethylaluminum for initiation of batch polymerization;
0- was injected into - air to increase the activity by about 25 times, and while maintaining the above hydrogen and ethylene concentrations, polymerization was carried out in SOt: for 9 minutes, and ethylene was further added to give a hydrogen concentration of 0.50 mO1%.
, polymerization was carried out for 2.0 minutes at an ethylene concentration of 40.0 mol%.

The slurry was then pumped for 3 minutes into autoclave D, which had previously been charged with 10q1 of liquid propylene and 50m of isoglobanol.

The interior of autoclave C1 was cleaned with liquid Propylene 2, and the washed propylene was also sent to autoclave D. Autoclave C1 was approximately 3-gauge and was ready for the next slurry receptacle. On the other hand, while charging impropanol at a rate of 1 hour to the autoclave D, the slurry was transferred from the lower part of the autoclave to a flash tank IK, and was then taken out as a powder through a hopper Ft. The discharge from autoclave D was continuous at about 40 Vh, and when the slurry was next received from autoclave C2, about 1011+ slurry remained in autoclave D. In autoclave C2, the slurry from autoclave B and methyl p-toluate were mixed for 30 minutes, and then the copolymerization operation was carried out in the same manner as in C1. Autoclave CI, C
Continuous polymerization was carried out for 25 hours, 25 times each for a total of 50 times, to obtain about 250 pieces of propylene-ethylene block copolymer as a product.

During the above operations, operation was possible without any abnormalities. The polymerization amount of the solid catalyst was determined from the π content in the product. The obtained block copolymer was dried at 60° C. and 100-Hf for 10 hours, granulated with commonly used additives, and its physical properties were measured. The results are shown in Table 2.

Reference Example In Figures 2 and 3, the catalyst synthesized in Example 1 (1) was used, the blending ratio of the solid catalyst, diethylaluminium chloride, and triethylaluminum was constant, and only the amount ratio of methyl p'-)ruylate was used. The activity when changing p-
The relationship between the amount of methyl toluate used, and the relationship between the activity and the amount of triethyl aluminum used when the blending ratio of the solid catalyst, diethylaluminum chloride, and p-methyl toluate is kept constant and only the amount ratio of triethyl aluminum is changed. . From this, the amounts of p-1-methyl ruylate and triethylaluminum necessary to obtain the desired activity can be estimated.

Example 2 0.65 g 73G- of p-)methyl ruylate added when receiving the slurry into autoclaves C1 and C2 was changed to 2.0 sg/30 kK of tetraethoxysilane to lower the activity to about 115, and and C
Polymerization was carried out in the same manner as in Example 1, except that the amount of triethylaluminum added at the start of the batch polymerization in step 2 was changed by 2 dK to increase the activity by about 2.5 times. The results are shown in Table 2.

Example 3 Methyl p-toluate added when receiving slurry into autoclaves C1 and 02 1.4sff/30-
was changed to 0.9d/30-ethyl orthoacetate to reduce the activity to about 1/4, and 25% of triethylaluminum was added to 11 at the start of batch polymerization in autoclaves C1 and C2.
The polymerization was carried out in the same manner as in Example 1 under the conditions shown in Table IK except that the activity was increased by about 2.0 times. The results are shown in Table 2.

Comparative Example 1 No additives or organoaluminum compounds were added to the batch polymerization tank, and polymerization was otherwise carried out in the same manner as in Example 1 under the conditions shown in Table IK.

The results are shown in Table 2. Impact resistance is very poor.

Comparative Example 2 Polymerization was carried out in the same manner as Comparative Example 1, except that the polymerization time of each stage of the batch polymerization was changed. The results are shown in Table 2. Impact resistance became quite good by increasing the ethylene content, but
Insufficient rigidity.

Comparative Example 3 Polymerization was carried out in the same manner as in Example 1, except that the slurry was discharged over 8 minutes after completion of batch polymerization.

The results are shown in Table 2.

[Brief explanation of drawings]

FIG. 1 shows an example of a polymerization apparatus for carrying out the method of the present invention. FIGS. 2 and 3 are graphs showing the relationship between the catalyst activity and the amount of methyl p-,)rulylate used, and the relationship between the catalyst activity and the amount of triethylaluminum used, respectively. Note that the units are expressed as relative values. A, B: Autoclave for continuous polymerization (J, C2: Autoclave for batch polymerization D = Autoclave for deactivation of catalyst E: Flash tank F: Hopper 11!2WJ-p-1 Louis I 311

Claims (2)

[Claims] (1) During multi-stage polymerization in which two or more polymerization tanks are connected using a stereoregular catalyst, polymerization is carried out in a continuous manner at a reaction ratio of ethylene/propylene of 6/94 x or less by weight, and the reaction of ethylene/propylene is carried out in a continuous manner. In a method for producing a propylene/-ethylene block copolymer by batchwise polymerization with a ratio of 15,785 to 9,515% by weight, the slurry is added to the slurry at the same time or before being transferred to a polymerization tank for batch polymerization. By adding a catalyst activity reducing agent, the catalyst activity is reduced to 1/4 or less of that without adding the catalyst activity reducing agent, and then batch polymerization is started after the slurry is transferred to a polymerization tank where batch polymerization is carried out. Batch polymerization is carried out under conditions in which the activity is increased to 1.1 times or more than the activity before adding the organoaluminium compound by adding an organoaluminum compound, and then after the batch polymerization is completed, the slurry is A method for producing an ethylene-propylene block copolymer, characterized in that the slurry is transferred to a zone where the operation for deactivating the polymerization activity is carried out for a time of 173 times or less of the predetermined polymerization time in the batch polymerization tank. (2) The method according to item 1, wherein the i-property reducing agent added to the batch polymerization tank at the time of slurry transfer is a compound having at least one C-0 or C-N feed.