JPS6036206B2 - Method for producing propylene block copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a propylene-ethylene block copolymer having a good balance between impact resistance and rigidity.

Since the invention of stereoregular catalysts by Ziegler and Natsuta et al., crystalline polyolefins have excellent rigidity and heat resistance.
In recent years, its production has been increasing worldwide as a general-purpose resin with excellent properties such as lightweight molded products.

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. Much research and development has already been carried out on methods to improve this drawback, and various improvement methods have been proposed. Among them, as an industrially useful method, a method of block copolymerizing propylene and other olefins, especially ethylene, is disclosed, for example, in Japanese Patent Publication No. 38-14834 and Japanese Patent Publication No. 39-1989.
-1830 Special Publication No. 39-15535 etc. However, block copolymers produced by these methods have drawbacks such as lower rigidity and transparency of molded articles than crystalline polypropylene, and whitening of deformed parts when deformed by impact or folding. To solve these problems, a method of carrying out block copolymerization in three stages was proposed in Japanese Patent Publications No. 44-20621 and No. 49-24593, and the resulting block copolymers had very excellent physical properties. On the other hand, a continuous production method is desired in order to increase the productivity of the propylene-ethylene floc copolymer per unit time and per unit volume of the polymerization tank, and to obtain a large quantity of products with as uniform physical properties as possible.

However, even if this method provides 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 method. In order to obtain a block copolymer with suitable physical properties in a continuous process, several polymerization stages with different reaction ratios of ethylenenopropylene are often provided, and therefore it is necessary to prepare polymerization tanks according to the number of stages. be. In addition, when multiple polymerization tanks are connected in series and polymerization is performed continuously, in a polymerization tank equipped with a complete mixing tank, the residence time of the catalyst differs depending on the polymerization tank, resulting in a distribution in the amount of polymerization per catalyst. Therefore, the physical properties of the produced polymers differ greatly between the continuous method and the batch method, and the former generally exhibits particularly lower impact resistance than the batch method. One way to solve these problems
In a method for producing an ethylene-propylene floc copolymer in which the polymerization of propylene alone or propylene-rich ethylene/propylene accounts for most of the total polymerization amount, the above-mentioned propylene alone or propylene-rich ethylene/propylene polymerization steps are carried out continuously. One possible method is to carry out several polymerization steps batchwise while changing the ethylene/propylene reaction ratio.By adopting this method, it is possible to achieve an excellent balance of physical properties using a relatively small number of polymerization vessels. A floc copolymer can be obtained.

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 can be significantly reduced.
However, rapid discharge of slurry from the continuous polymerization tank
The level of the polymerization tank in which continuous polymerization is being carried out is suddenly changed, causing problems such as difficulty in controlling the temperature of continuous polymerization and the molecular weight of the produced polymer.
Furthermore, if a pump is used to transport the slurry, a pump with a large capacity is required, which increases equipment costs. On the other hand, even if the slurry is rapidly transferred from the batch polymerization tank to the deactivation process, it will not affect the continuous polymerization reaction zone. It is also possible to place the polymerization tank at a higher position than the deactivation step to rapidly transfer the slurry to the deactivation step. As for the influence on the deactivation process, it is also possible to set the reaction conditions of the deactivation process close to the reaction conditions in a batch polymerization tank to drastically reduce the influence of slurry discharge. The purpose of the present invention is to produce a propylene-ethylene flock copolymer having excellent physical properties such as impact resistance and high rigidity without difficulty in controlling the polymerization process, and in comparison with batch polymerization. The object of the present invention is to provide a method for increasing productivity per unit time per unit volume of a polymerization tank without substantially reducing the physical properties of the resulting polymer.

The present invention uses a stereoregular catalyst to perform ethylene/fluoride polymerization in multi-stage polymerization in which two or more polymerization tanks are connected.

. Polymerization is carried out in a continuous manner with a reaction ratio of pyrene of 6'94% by weight or less, and a reaction ratio of ethylene/propylene of 15'85 to 15'85.
In a method for producing a propylene-ethylene floc copolymer by batchwise polymerization of 95 to 5% by weight, at the same time or before transferring the slurry to a polymerization tank for batch polymerization, By adding a catalyst activity reducing agent, the catalyst activity when no reducing agent is added is reduced by 1'4.
By adding an organoaluminum compound when starting batch polymerization after transferring the slurry to a polymerization tank where batch polymerization is then carried out, the activity can be reduced to 1.1 times the activity before adding the organoaluminium. Batch polymerization is carried out under conditions where the activity is increased as described above, and then, after the completion of the batch polymerization, the polymerization activity of the slurry is deactivated for a period of 1'3 or less of the predetermined polymerization time in the batch polymerization tank. The present invention relates to a method for producing an ethylene-propylene floc copolymer, which comprises transferring a slurry for a time of . 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 propyreso, but...
A solid catalyst containing at least three types of elements: Mg, Ti, and CI;

}Catalysts made of organoaluminum compounds are preferred. Solid catalysts containing at least three elements, Mg, h, and CI, can be produced by various methods. It can be obtained by the method proposed for candy etc. Specifically, magnesium halides (for example, anhydrous MgC12) and various organic compounds, such as aromatic orthocarboxylic acid esters, alkoxy silicon and halogenated hydrocarbons, orthocarboxylic acid esters and halogenated hydrocarbons, or carboxylic acid esters. A solid catalyst can be obtained by heat-treating a co-pulverized product of AIC13 and AIC13 and alcohol with titanium halide. Alternatively, a solid support containing Mg and CI that is insoluble in an inert solvent is synthesized by reacting an organomagnesium compound that is soluble in an inert solvent with various halogenating agents, and is further treated with an electron donating compound, titanium halide. It can also be obtained by processing. The {o-organoaluminum compound which is one component of the catalyst has the general formula AIRmX3-m
(In the formula: R is a hydrocarbon residue having 1 to 12 carbon atoms, X is a halogen atom, and an organoaluminum compound represented by Ism-3 is preferably used.

For example, triethylaluminum, tri-n-butylaluminum, triisoptylaluminium, tri-n-hexylaluminum, diethylaluminum monochloride, etc. may be used alone or in combination of two or more. Further, by using a compound having at least one C-○ or C-N bond in the catalyst system, the stereoregularity of the obtained polymer can be increased and the physical properties can be well balanced.
As the compound having at least one C-○ or C-N bond, esters, ethers, orthoesters, alkoxy silicones, amines, amides, phosphate esters, etc. are used, and more specifically, ethyl benzoate, methyl tolylate, etc. , methyl orthobenzoate, tetraethoxysilane, phenyltriethoxysilane, dibutyl ether, triethylamine, diethylaniline, triethyl phosphate and the like are preferably used. The ratio of each component constituting the catalyst used in the present invention is arbitrary, and the appropriate range varies depending on the compound used, but generally the organoaluminum compound is 0.1 to 0.1 to 1 mole of Til in the solid catalyst. The amount of the compound having at least one C-○ or C-N bond is in the range of 0 to 250 mol. In the method of the present invention, 80% or more of the polymerization in which the reaction ratio of ethylene/propylene is 6/94% by weight or less is carried out continuously using a polymerization tank in which two or more vessels are connected, and the reaction ratio of ethylene/propylene is 15/94% by weight or less. An ethylene-propylene block copolymer is produced by carrying out 90% or more of the polymerization of 85 to 95'5% by weight batchwise. Of course, polymerization in which the reaction ratio of ethylene/propylene is 6/94% by weight or less also includes 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. .
Polymerization with an ethylene/propylene reaction ratio of 6/94% by weight or less is necessary to maintain a good balance between impact resistance and rigidity of the ethylene/propylene flock copolymer, and in particular, polymerization with this reaction ratio reduces the total polymerization amount. It is desirable that the amount is 60 to 95% by weight of the ethylene-propylene floc copolymer in order to increase the rigidity of the ethylene-propylene floc copolymer. The polymerization temperature at the above reaction ratio varies depending on the catalyst system, but is generally 40-90qo, especially 60-90qo.
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 95.
/5% by weight is an essential step in order to obtain a propylene-ethylene floc copolymer with excellent impact resistance, and the polymerization is carried out in the presence of an inert solvent or when the inert solvent is substantially It is also possible to perform bulk polymerization using propylene itself as a solvent, which is not present in the polymer, or a gas phase polymerization method in which a polymerization solvent is substantially absent.

The above-mentioned self-polymerization temperature varies depending on the reaction ratio of ethylene/propylene, etc., but is generally 30 to 700°, particularly 40 to 600°.
0 is preferred. 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, so that the catalytic activity is 1'4 or less than the catalyst activity when no reducing agent is added. After transferring the slurry to a polymerization tank where batch polymerization is carried out, an organoaluminum compound is added at the start of batch polymerization to reduce the activity to 1.5% before adding the organoaluminium.
Batch polymerization is carried out under conditions in which the activity is increased by more than 1 times, and then after the batch polymerization is completed, the polymerization activity of the slurry is deactivated. It is characterized by transferring slurry in 1/3 of the time or less.

Polymer obtained because unplanned and uncontrollable polymerization occurs while transferring the slurry from the continuous polymerization process to the batch polymerization process, from the batch polymerization process to the deactivation process, and while adjusting the hydrogen concentration in the gas phase. The balance of physical properties deteriorates significantly.

Therefore, in order to reduce the above-mentioned unplanned and uncontrollable amount of polymerization 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 1' of the original activity. Lower, preferably 1'4 to 1'10
decrease to. If it is greater than 1'4, the effect of uncontrollably reducing the amount of polymerization will be reduced, while if it is less than 1'10, the amount of organoaluminum compound added to restore activity will increase.

After the slurry is transferred to the batch polymerization vessel, an organoaluminum compound is added to restore appropriate catalytic activity determined by the batch polymerization time and amount of polymerization.

The usage ratio of organoaluminum depends on the type and amount of the activity reducing agent, but is at least 1.1 times the activity before adding the organoaluminum compound, preferably 1.1 to 10 times the activity before adding the organoaluminum compound.
This is an amount that doubles the activity. 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 slurry from a batch polymerization vessel to a zone containing a deactivator. By keeping the time required for transfer less than 1'3 of the predetermined polymerization time in the batch polymerization tank, uncontrolled polymerization during transfer can be made virtually negligible. The shorter the time required for transfer, the less uncontrolled polymerization will occur, 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 reduced. The activity reducing agent can be used as long as it reduces the catalyst activity, and various organic compounds and NC13,
Inorganic compounds such as SIC14 are used, but those that reduce the activity without significantly reducing the stereoregularity of the resulting polymer are preferred, particularly those that reduce the activity without reducing the stereoregularity and contain a small amount of It is preferable to use a compound whose activity can be restored by addition of an organoaluminum compound.

Examples include compounds having at least one C-- or C-N bond which are used as preferred components of the catalyst systems mentioned above. Specific examples of compounds are as described above. Furthermore, as the organoaluminum compound used to restore the activity, the organoaluminum compound used as a component of the catalyst system described above is preferably used.

By using the method of the present invention, a propylene-ethylene floc copolymer with an excellent balance of impact resistance and rigidity can be efficiently provided under controlled conditions, and 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) ASTM D1238 bending rigidity ASTM D747-63 Izot (with notch) ASTM D256-56 DuPont
MI is 230q0 based on JIS K6718,
Under the condition of load 2.16k9, bending rigidity is 20qC, and Izod and DuPont impact strength is 20qo.
and -1030, respectively.

The intrinsic viscosity number (abbreviated as below) was 135 qo, which was measured using a tetralin solution. Isotactic Isodex (hereinafter abbreviated as 11) is boiling n-hebutane extraction residual polymer (%)
The total polymer was calculated as

Example 1 {i- Preparation of solid catalyst component A vibratory mill equipped with 4 pots each having an internal volume of 4 and containing 9K9 steel balls with a diameter of 12 mm is prepared.

300 g of magnesium chloride in each pot in the atmosphere,
60 parts of tetraethoxysilane and 45 parts of Q,Q,Q-trichlorotoluene were added and pulverized for 4 times. Internal volume 50
Add 3k9 of the above-mentioned pulverized material and 20% of titanium tetrachloride to the autoclave, heat at 8,000°C for 2 hours, remove the supernatant solution by decantation, then add 35% of n-heptane, heat at 80°C for 5 minutes, and then decant. After repeating the washing operation seven times to remove the supernatant liquid in a station, 20 tons of n-hebutane was added to prepare a solid catalyst slurry. When a part of the solid catalyst slurry was sampled and analyzed after n-hebutane was evaporated, 1.4% by weight of Ti was found in the solid soot.
It contained. tii) Polymerization Polymerization is carried out using the polymerization apparatus shown in FIG.

Thoroughly dried and purged with nitrogen, an autoclave with an internal volume of 50 mL was charged with 30 mL of n-heptane, 50 mL of the above solid catalyst, 240 mL of diethyl aluminum and chloride, and 140 mL of methyl p-toluate. . This mixture is used as a catalyst slurry mixture. Thoroughly dried, purged with nitrogen, and further purged with propylene gas, with an internal volume of 300
The autoclave A and B are connected in series, and the internal volume is 2.
00 The autoclave CI and C2 are connected next to autoclave B in parallel. The autoclave D having an internal volume of 300 is connected in series to autoclaves CI and C2. Charge propylene 60k9 to autoclaves A and B. 1 using the above catalyst slurry mixture as a solid catalyst
Triethylaluminum, another organoaluminum catalyst component, was added to the autoclave A at a rate of 1.5 m/h, and liquid propylene was added to the autoclave A at a rate of 30 k9/h.
Charge to. Autoclave B was continuously charged with triethylaluminum at a rate of 30 k/h and polypropylene slurry from autoclave A at a rate of 30 k9/h.
Autoclape A while continuously extracting at 0k9/h
Hydrogen was charged to maintain the gas phase hydrogen concentration of B and B at the amount shown in Table 1, and polymerization was carried out at 730° C. After 6 hours had passed from the start of polymerization, when the polymerization was stabilized, what happened in the continuous polymerization section and 11
In order to confirm whether a powder having the same properties was obtained, a small amount of slurry was taken out from autoclave B and the physical properties of the powder were measured. The results are listed in Table 2 under the section of continuous polymerization final powder physical properties. Next, the slurry is continuously withdrawn from the lower part of the autoclave B and methyl p-toluate is simultaneously extracted from the autoclave CI at a rate of 1.4'/30 feet.
After receiving the slurry into CI for 30 minutes, the slurry and methyl p-toluate from autoclave B was transferred to autoclave C2. At the same time as the CI receives the slurry, 5 kg of liquid propylene is injected while purging the gas phase to bring the internal temperature to 5,000 and at the same time reduce the hydrogen concentration to 0. It was expressed as pol%. During this period, the activity was reduced to about 1/5 by charging p-tolylic acid. Further, ethylene and hydrogen were charged to make the hydrogen concentration in the gas phase 0.55 vol% and the ethylene concentration 35.0 mol%. To start the batch polymerization, 3.0% of triethylaluminum was added at once to increase the activity to about 2.0%. Polymerization was carried out at 50 oo for 9 minutes as the first stage of batch polymerization while maintaining the above hydrogen and ethylene concentrations, and ethylene was further added to give a hydrogen concentration of 0.5 ol% and an ethylene concentration of 4.
Polymerization was carried out for 2.0 minutes as the second stage of batch polymerization at 0.0 mol %. Next, liquid propylene 10k9 in advance,
In autoclave D containing 50% of isopropanol, sliver IJ was added for 3 minutes, less than 1/3 of the total 11 minutes of the 9 minutes of the first stage and 2 minutes of the second stage of the above batch polymerization. was pumped. The interior of the autoclave CI was washed with liquid propylene, and the washed propylene was also sent to the autoclave D. The autoclave CI was ready to receive the next slurry at approximately 3 kg/loaf-gauge. On the other hand, Autocrepe D
The slurry was transferred from the lower part of the bag to a flash tank E while being filled in a bag at 1/h of isopropanol, and then taken out as a powder via a hopper F. autoclave. The discharge from D was continuous at a rate of about 40k9/h, and when the slurry was next received from autoclave C2, about 10k9 of slurry remained in autoclave D. Autoclave C2 received the slurry from autoclape B and methyl p-toluate for 3 minutes, and then carried out the copolymerization operation in the same manner as CI. The autoclave C1 and C2 were operated 25 times each for a total of 50 times, and continuous polymerization was carried out in two groups, producing approximately 250 k9 of fluoropyrene-ethylene fluoride. A Tsuku copolymer was obtained. During the above operations, operation was possible without any abnormality. The amount of polymerization per solid catalyst was determined from the Ti content in the product. The obtained block copolymer was dried at 6,000 and 100 Yanagi Hg for one hour, 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 {i} of Example 1 was used, the blending ratio of the solid catalyst, diethyl aluminum chloride, and triethyl aluminum was constant, and the quantitative ratio of methyl p-tolylate was used. The relationship between the activity and the amount of methyl p-toluate used when only the amount of triethylaluminum used is changed, and the mixing ratio of the solid precatalyst, diethylaluminum chloride, and methyl p-tolylate is kept constant and only the amount ratio of triethylaluminum is changed. The relationship between the activity and the amount of triethylaluminum used is shown below.

From this, it is possible to estimate the amounts of methyl p-tolylate and triethylaluminum required to obtain the desired activity. Example 2 When receiving the slurry into autoclave CI and C2, the activity was changed to about 1/3 by changing the 0.6'/3 of p-methyl tolylate to the 2.0'/3 of tetraethoxysilane. 5 and autoclave CI and C
The triethylaluminum added at the start of the batch polymerization in step 2 was changed to 2' to increase the activity to about 2. Polymerization was carried out under the conditions shown in Table 1 in the same manner as in Example 1, except that the polymer was used as a polymer.

The results are shown in Table 2. Example 3 The methyl p-tolylate 1.4M/30 side added when receiving the slurry into the autoclave CI and C2 was changed to ethyl orthoacetate 0.9'/30 side to reduce the activity to about 1/4. The triethylaluminum added at the start of the batch polymerization in autoclaves CI and C2 was changed to above 25 to increase the activity to about 2. Polymerization was carried out in the same manner as in Example 1 under the conditions shown in Table 1 except for the noise.

The results are shown in Table 2. Comparative Example 1 Batch Polymerization was carried out in the same manner as in Example 1 under the conditions shown in Table 1 without adding any additives or organoaluminum compounds to the polymerization tank.

The results are shown in Table 2. Impact resistance is very poor. Comparative Example 2 Polymerization was carried out in the same manner as in Comparative Example 1, except that the polymerization time of each stage of the batch polymerization was changed.

The results are shown in Table 2. Although the impact resistance was considerably improved by increasing the ethylene content, the rigidity was insufficient.
Comparative Example The same procedure as in Example 1 is shown in Table 1, except that the slurry was discharged after the completion of three batch polymerizations over a period of 8 minutes, which was more than 1/3 of the 11 minutes (9 minutes and 12 minutes) of the batch polymerization polymerization time. Polymerization was carried out under the following conditions.

As a result, as shown in Table 2, the balance between rigidity and impact resistance was significantly inferior to that of Example 1. Two fences at a crossroads, two funano capes, and a thousand reeds.

Kataarizaki Reef Honey key Kuresho Bending main cloud "cape 1 11 Lidden thunder Lost tan

[Brief explanation of the drawing]

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-tolylate 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...autoclape for continuous polymerization, C1, C2...autoclape for batch polymerization, D...autoclape for catalyst removal, E...flash tank, F・・・・・・Hotsu/gu-. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In 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% by weight or less, and ethylene /
In a method for producing a propylene-ethylene block copolymer by batchwise polymerization at a propylene reaction ratio of 15/85 to 95 to 5% by weight, the slurry is transferred simultaneously or simultaneously to a polymerization tank for batch polymerization. By adding a catalyst activity reducing agent to the slurry before carrying out the polymerization, the catalyst activity is reduced to 1/4 or less of the catalyst activity when the reducing agent is not added, and then after the slurry is transferred to a polymerization tank for batch polymerization, batch polymerization is performed. Batch polymerization is carried out under 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 polymerization, 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 of the ethylene-propylene block copolymer is carried out in a time that is ⅓ or less of the predetermined polymerization time in the batch polymerization tank. 2. The method according to item 1, wherein the activity reducing agent added to the batch polymerization tank when transferring the slurry is a compound having at least one C-O or C-N bond.