JPH0670108B2 - Continuous production method of propylene-ethylene block copolymer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a continuous production method of a propylene-ethylene block copolymer, and more specifically, the present invention has an extremely high quality balance such as impact resistance, rigidity and processability. The present invention relates to a method for producing a good copolymer with good productivity.

[Prior Art] Crystalline polypropylene produced by using a stereoregular catalyst has excellent properties such as rigidity and heat resistance, but on the other hand, it has a problem that impact strength, especially at low temperature, is used. Its range of use was limited. Therefore, as a method for improving this drawback, many block copolymerization methods with ethylene or other α-olefins have been proposed.
The block copolymerization method can greatly improve low-temperature impact strength without significantly impairing the excellent properties of polypropylene such as rigidity and heat resistance, but on the other hand, it has problems in production and quality peculiar to the block copolymerization method. There has occurred. That is, when the block copolymer is produced by the batch polymerization method, the amount of the polymer obtained per unit time per unit polymerization unit is lower than that in the continuous polymerization method, and the cost is high. On the other hand, in the multi-stage continuous polymerization method, the residence time of each catalyst particle in each stage of the polymerization vessel has a distribution (which is considered to be close to a complete mixing tank distribution), so that the polypropylene part (the part containing propylene significantly) and the polyethylene part This is a collection of polymer particles having a distribution in the content ratio of a part (a part containing a relatively large amount of ethylene), resulting in a defect in quality due to the nonuniformity of the distribution. Many proposals have been made to improve such drawbacks of the continuous polymerization method.
For example, JP-A-58-49716, JP-A-55-116716, JP-A-58-69
215 etc. propose a method of classifying the slurry after exiting the polypropylene polymerized portion by a cyclone and returning fine particles to the polypropylene polymerized portion again, but the classification by the catalyst particle size does not always match the residence time distribution. The improvement of non-uniformity is insufficient.

JP-A-57-195718 and JP-A-58-29811 describe a method of intermittently supplying the catalyst and withdrawing the slurry from the polymerization vessel to reduce the amount of the catalyst entering the polyethylene polymerization section while the residence time is short. However, it has a problem that the polymerization reaction becomes unstable.

Further, by treating the slurry leaving the polypropylene polymerized portion with an electron-donating compound or the like in the same manner as in the method of the present invention, the catalyst particles (short-pass catalyst) that have come out with a short residence time are selectively deactivated. Several methods have been proposed. For example, JP-A-58-32615, 57-174310, 57-17431
1,57-147508 and the like propose a halogen compound as an additive for the deactivation, but it is still insufficient in terms of the effect of selective deactivation of catalyst particles. Also, JP-A-57-14511
5,55-115417 proposes various electron-donating compounds, but the use of the compounds in the ranges used in the examples has the following object of the present invention, that is, physical properties equivalent to the batchwise polymerization process. The effect was insufficient to achieve the continuous production method of the block copolymer.

[Object of the Invention] The present inventor has previously described in Japanese Patent Application No. 60-255,867 a propylene-based multi-stage process in which three or more tanks are continuously used.
In the continuous production method of ethylene block copolymers, a method of using two or more tank polymerization vessels in series as the first stage was proposed.

The present invention relates to a method for producing the block copolymer having excellent physical properties by using a polymerization vessel having only one tank as the first stage by specifying the conditions.

That is, the present invention suppresses the polymerization reaction in the polyethylene polymerized portion by selectively deactivating the catalyst that has passed through the polypropylene polymerized portion while keeping the residence time much shorter than the average residence time. It was possible to solve the problems of the prior art by finding a compound having an effect of preventing the formation of polymer particles having a remarkably high proportion of polyethylene in the polymerized part, which is far greater than the conventionally known compound. .

As is clear from the above description, the object of the present invention is to solve the problems of the prior art in a continuous production method of a propylene-ethylene block copolymer using a stereoregular catalyst, by using a specific polymerization method and a specific compound. It is an object of the present invention to provide a method for producing a copolymer having a good balance of quality such as impact resistance, rigidity and workability with high productivity, which is solved by use.

[Structure / Effect of Invention] The present invention has the following main structure (1) and embodiment structures (2) and (3).

(1) Titanium-containing solid catalyst component (A) and general formula Al ▲ R ² _m
▼ X _3- m (wherein R ² represents a hydrocarbon group having 1 to 20 carbon atoms,
m is a number of 3m> 1.5) and a stereoregular catalyst in which an organoaluminum compound (B) is combined is used as a solvent with an inert solvent or propylene, and two or more tanks are connected to be used as a polymerization vessel. In a continuous production method of a propylene-ethylene block copolymer by a multi-step process, a 1-layer polymerization reactor is used as a first step, and ethylene / (ethylene + propylene) = 0 to 5% by weight of a monomer is supplied to mainly produce propylene. The polymerization step (i) described above was continuously carried out to produce 60 to 95% by weight of the total polymerization amount, and glycol ether (C) was added to the above-mentioned catalyst as a second step in the polymerization reaction mixture obtained in the first step. To the titanium component in component (A), Ti was added continuously in (C) / (A) so that Ti = 0.01 to 1.0 (mol / atom), and the addition reaction mixture was continuously added to one or more tanks. Using the polymerization vessel of Supply momer of ethylene / (ethylene + propylene) = 10-100% by weight,
A method comprising continuously carrying out a polymerization step (ii) containing a relatively large amount of ethylene to produce 5 to 40% by weight of the total polymerization amount.

(2) Melt index of the polymer obtained in the polymerization step (i) mainly composed of propylene (hereinafter referred to as MI [1])
Melt index of the polymer obtained in the polymerization step (ii) containing a relatively large amount of ethylene and ethylene (hereinafter referred to as MI [2])
The method according to the above (1), wherein and have a relationship of logMI [1] / MI [2] = − 1 to 3 (1).

(3) The method according to the above item (1), wherein the amount of glycol ether (C) added is such that the catalytic activity after the addition is 30 to 80% of the catalytic activity before the addition.

(4) The method according to item (2), which has a relationship of logMI [1] / MI [2] = 0 to 2 (2) in the expression (1).

As the titanium-containing solid component (A) used in the present invention,
There is no particular limitation as long as it is a solid catalyst containing titanium,
Highly active reduced titanium trichloride, titanium tetrachloride, magnesium compound and electron donating compound obtained by reducing titanium tetrachloride with organic aluminum and further treating with electron donating compound and electron accepting compound etc. So-called highly active catalysts such as supported catalysts obtained by the above are preferable. This is because the addition of glycol ether lowers the catalytic activity, and the use of a catalyst having a high predictive activity facilitates deashing after polymerization.

The organoaluminum compound (B) has the general formula Al ▲ R
A compound represented by ² _m ▼ X _3- m (wherein R ² represents a hydrocarbon group having 1 to 20 carbon atoms, X represents a halogen atom, and m represents a number of 3m> 1.5) is used. It For example, diethyl aluminum chloride, triethyl aluminum,
Tri-n-butylaluminum, triisobutylaluminum, tri-n-hexylaluminum, diethyl bromide, diethyl iodide and the like can be used alone or in combination.

Further, in addition to the titanium-containing solid component (A) and the organoaluminum compound (B), compounds generally used as the third component of the catalyst such as an electron donating compound can be used. The compound is, for example, a compound having atoms such as oxygen, nitrogen, sulfur, phosphorus, silicon, etc., and ethers, alcohols, esters, aldehydes, fatty acids, ketones, nitriles, amines, amides, urea Alternatively, thioureas, isocyanates, azo compounds, phosphines, phosphites, phosphanites, thioethers, thioalcohols, organic silicon compounds and the like. However, the third component, which is essentially used in the second step of the method of the present invention, is as follows. That is, examples of the glycol ethers used in the present invention include ethylene glycol monoalkyl ether, ethylene glycol dialkyl ether, propylene glycol monoalkyl ether, propylene glycol dialkyl ether, and the like. More specifically, ethylene glycol monomethyl ether,
Ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, ethylene glycol diethyl ether, ethylene glycol monopropyl ether,
Ethylene glycol dipropyl ether, ethylene glycol monobutyl ether, ethylene glycol dibutyl ether, propylene glycol monomethyl ether, propylene glycol dimethyl ether, propylene glycol monoethyl ether, propylene glycol diethyl ether, propylene glycol monopropyl ether, propylene glycol dipropyl ether, propylene glycol Monobutyl ether, propylene glycol dibutyl ether, etc. may be mentioned, and further, there are condensates of glycols such as diethylene glycol monoalkyl ether, diethylene glycol dialkyl ether, triethylene glycol monoalkyl ether, triethylene glycol dialkyl ether, tetraethylene glycol monoalkyl ether. Kill ether, tetraethylene glycol dialkyl ether, dipropylene glycol monoalkyl ethers, dipropylene glycol dialkyl ether, tripropylene glycol monoalkyl ethers, tripropylene glycol dialkyl ethers, tetrapropylene glycol monoalkyl ethers, tetrapropylene glycol dialkyl ethers,
Examples of the alkyl group include polyethylene glycol monoalkyl ether, polyethylene glycol dialkyl ether, polypropylene glycol monoalkyl ether, polypropylene glycol dialkyl ether, and the like, and a chain hydrocarbon having 1 to 20 carbon atoms can be mentioned. It is also possible to use glycol ethers obtained by reacting ethylene oxide with propylene oxide. The amount of these ethers (C) used varies depending on the type of glycol ether, but the titanium content of the titanium-containing catalyst component (A) is (C) / (A) Ti = 0.01-1.0 mol. Used in the / atomic ratio. That is, it is preferable to add the (C) within a range of 30 to 80%, with 100% as the catalytic activity when glycol ether is not added.
If the amount of addition is too large, the effect of inactivating the short-pass catalyst is great, but the overall catalyst activity is greatly reduced, which is not economically preferable, and the polymerization step (i) and the polymerization step (ii)
It is not preferable because the control of the polymerization amount ratio is restricted. On the other hand, if the amount of (C) is too small, the effect of selectively deactivating the short-pass catalyst becomes insufficient, which is not preferable.

The glycol ethers (C) used in the present invention are remarkably excellent in effect as compared with conventionally known ketones, amines, amides, alkyl ethers, carboxylic acid esters and halogen compounds. The reason for this is unknown, but the (C) reacts with the organoaluminum compound (B) to form an insoluble solvent-insoluble complex, and it becomes difficult to react with the catalyst inside the polymer particles, so that a short-pass catalyst is used. It is also considered that the action of preferentially inactivating is significantly exhibited.
That is, it is assumed that it is necessary condition that a liquid complex that is insoluble in an inert solvent is formed and that the complex does not easily penetrate into the inside of polymer particles.

In the polymerization of the present invention, as the first step (i), a polymerization mainly containing propylene is carried out. As the inert solvent, commonly used ones such as propane, butane, hexane, heptane and kerosene can be used, or propylene itself can be used as a solvent. Usually the polymerization temperature is 20-80
℃, preferably 50 ~ 75 ℃, polymerization pressure 0 ~ 50kg / c
It is carried out at m ² G with an average residence time of 30 minutes to 15 hours. To control the molecular weight, hydrogen is usually used and the melt index MI = 0.5 to 200 is used.

The first stage monomer supply composition was ethylene (▲ C
⁼ ₂ ▼) / {Ethylene (▲ C ⁼ ₃ ▼) + Propylene (▲ C ⁼ ₂
▼)} = 0 to 5 wt%. If there is too much ethylene than 5 wt%, the physical properties of polypropylene such as rigidity and heat resistance will deteriorate.

Further, as the third component of the monomer, 1-butene, 4-methylpentene-1, styrene, non-conjugated dienes and the like can be added and supplied in an amount of 0 to 10% with respect to propylene.

The polymerization amount in the first stage is 60 to 95% by weight, preferably 75 to 90% by weight, based on the total amount of the propylene-ethylene block copolymer finally obtained. If the amount of polymerization is more than the above range, the rigidity of the product will be deteriorated, and if it is too small, the improvement of low temperature impact strength will be insufficient.

The first stage polymerization is carried out using one polymerization vessel. When the number of units is two or more, a considerable improvement effect corresponding to the method of the present invention is recognized, but it is disadvantageous in that the amount of capital investment becomes high and the operation becomes complicated. In addition, it may be difficult to add a polymerization vessel to equipment that is already operated with one unit due to the layout restrictions.

The polymerization slurry (i), that is, the polymerization reaction mixture, which has completed the first step is continuously withdrawn, added with glycol ether (C), and then sent to the second step polymerization step (ii). The addition of glycol ether may be continuous or intermittent, but 1/8 of the average residence time in the second stage
It is necessary to maintain the addition interval within. If it is too long, the effect of the additive (C) becomes insufficient.

As a method for adding the glycoether (C), it is also possible to install a tank between the first stage (i) and the second stage (ii) (for example, a separation tank for propylene monomer) and add it there. It can also be added directly to the second stage (ii). In the second step (ii), the polymerization temperature is usually 20 to 80 ° C,
It is preferably carried out at 40 to 70 ° C., a pressure of 0 to 50 kg / cm ² G, and an average residence time of 20 minutes to 10 hours. Hydrogen is usually used to control the molecular weight, and the concentration in the gas phase is 1 to 40 mol%.
It is carried out in. The molar ratio of ethylene (▲ C ⁼ ₂ ▼) and propylene (▲ C ⁼ ₃ ▼) fed to the second stage (ii) is
▲ C ⁼ ₂ ▼ / ▲ C ⁼ ₂ ▼ + ▲ C ⁼ ₃ ▼ = 10 to 100% by weight, preferably 20 to 70% by weight, and the polymerization amount is based on the final propylene-ethylene block copolymer. 5-40% by weight,
It is preferably 10 to 25% by weight. In addition to ethylene and propylene, other α-olefins, non-conjugated dienes and the like may be used together. MI [1] of the polymer obtained in the polymerization step (i)
And the MI [2] of the polymer obtained in the polymerization step (ii) Is preferred, and more preferably Is. Here, MI is a value measured by the method of ASTM D-1238 at 230 ° C. and a load of 2.16 kg.

MI [1] is the measured MI value of the polymer in the first stage.
[2] is the measured MI value after completion of the second stage {MI [1 + 2]}, the first-stage polymer fraction (W ₁ ) and the second-stage polymer fraction (W ₂ ) It is a value calculated by the equations (2) and (3).

logMI [1 + 2] = W ₁ logMI [1] + W ₂ logMI [2] _{...... (2) W 1 + W} 2 = 1.0 ...... (3) In the case of, the obtained polymer has low temperature impact strength, tensile elongation,
It is inferior in terms of weld strength and is not preferable. In addition, a large amount of a polymer soluble in the polymerization solvent is generated, which is inferior in terms of economy and plant operability, which is not preferable.

on the other hand In the case of, the obtained polymer cannot completely prevent the generation of FE (fish eye) and is inferior in terms of low temperature impact strength and product appearance, which is not preferable.

As described in detail above, the present invention makes it possible to achieve an effect significantly exceeding the known art by using specific polymerization conditions and additives, and more specifically described by examples. However, the present invention is not limited to this.

The measuring method in the examples is shown below.

MI; ASTM D-1238 (g / 10min) 230 ° C, 2.16kg load Ethylene content; by infrared absorption spectroscopy. (W
t.%) Polymerization ratio of polymerization (i) and polymerization (ii); A copolymer prepared by changing the reaction ratio of ethylene / propylene was prepared in advance, and this was used as a standard sample. Then, the ethylene / propylene reaction amount ratio in the polymerization step (ii) was determined and calculated from the ethylene content in the total polymer. (Wt / wt) Catalytic activity of polymerization step (ii); activity without glycol ether is 100%.

FE; Chisso method (pieces / 1000 cm ² ) Flexural modulus; JIS K6758 (kgf / cm ² ) Tensile strength; JIS K6758 (kgf / cm ² ) Tensile breaking elongation; JIS K6758 (%) Izod impact strength (II); JIS K6758 (kgfcm / cm) DuPont impact strength (DI); Chisso method (kgcm) 50 x 50 mm, 2 mm thick injection molded piece has a hemisphere with a radius of 6.3 mm at -20 ° C with DuPont impact tester Contact the wick and drop the weight from the height of 1m onto the wick to obtain the value at which 50% is destroyed.

Example 1 1) Preparation of catalyst n-hexane 6l, diethyl aluminum monochloride (DE
AD) 5.0 mol and diisoamyl ether 12.0 mol were mixed at 25 ° C. for 5 minutes and reacted at the same temperature for 5 minutes to obtain a reaction product solution (I) (diisoamyl ether / DEAC molar ratio 2.4). Titanium tetrachloride 40 in a reactor with a stirrer replaced with nitrogen
The reaction product solution (I) is added to this by heating to 35 ° C.
After dripping the entire amount of the product in 180 minutes, keep it at the same temperature for 30 minutes, and
The temperature was raised to 5 ° C and the reaction was continued for another 1 hour, then cooled to room temperature, the supernatant was removed, 30 l of n-hexane was added and decantation was repeated 4 times to obtain 1.9 kg of solid product (II).
Got

The total amount of this (II) was suspended in 30 liters of n-hexane at 20 ° C at a temperature of 1.6 kg of diisoamyl ether and 3.5 parts of titanium tetrachloride.
kg was added at room temperature for about 5 minutes and reacted at 65 ° C. for 1 hour. After completion of the reaction, the mixture was cooled to room temperature (20 ° C), the supernatant was removed by decantation, 30 l of n-hexane was added and stirred for 15 minutes, and the mixture was allowed to stand and the supernatant was removed 5 times. After that, it was dried under reduced pressure to obtain a solid product (III).

2) Preparation of catalyst In a tank with an internal volume of 50 liters, 40 liters of n-hexane, 850 g of diethylaluminum chloride, 360 g of the above solid product (III) and 3.8 g of methyl paratoluate were charged, and then propylene gas was maintained while stirring at 30 ° C. Was supplied at 180 g / H for 2 hours for pretreatment.

3) Polymerization method Polymerization was carried out using the apparatus shown in FIG.

Propylene 14l / H, n-hexane 26l per hour in a 150l polymerization vessel 1
/ H and 160 ml / H of catalyst slurry were continuously supplied, the pressure of the polymerization vessel was 8 kg / cm ² G, and the temperature was 70 ° C. The pressure was finely adjusted by changing the supply amount of the catalyst slurry. Further, hydrogen was supplied while observing the process gas chromatography analysis value so that the hydrogen concentration in the gas phase part was as shown in Table 1. The slurry discharged from the polymerization vessel 1 was supplied to the pressure drop tank 2.

The pressure drop tank 2 was adjusted to 70 ° C. and 0.5 kg / cm ² G, and glycol ether as shown in the same table was added. The slurry extracted from the pressure drop tank 2 was supplied to the polymerization vessel 3.

The polymerizer 3 supplies ethylene at 0.55 kg / H at 60 ° C., the gas phase gas composition of the polymerizer 3 is ethylene / (ethylene + propylene) = 0.35, and the hydrogen concentration in the gas phase is shown in Table 1. Propylene and hydrogen were fed so as to maintain the indicated values.

The slurry discharged from the polymerization vessel 3 was depressurized in the depressurization tank 4, the catalyst was deactivated with methanol, and the product powder was recovered through neutralization with caustic soda water, washing with water, powder separation, and drying (about 5 kg / Hr. .). On the way, the slurry was sampled in the pressure drop tanks 2 and 4 and analyzed together with the product powder.

4) Granulation method 8 kg of the product powder obtained above, 0.008 kg of phenolic heat stabilizer and 0.008 kg of calcium stearate were added and mixed for 2 minutes at room temperature with a high-speed stirring mixer (Note. Henschel mixer; trade name). The mixture was granulated using an extruder having a screw diameter of 40 mm.

(5) Manufacture of injection-molded product The granulated product obtained in 4) is melted at a molten resin temperature of 23 using an injection molding machine.
Create a JIS type test piece at 0 ° C and mold temperature of 50 ° C. Regarding this tetrapiece, the humidity is 50% and the room temperature is 23 ° C.
The condition was adjusted for 72 hours. Then, the physical property values shown in the table were measured.

6) Measurement of fish eye (FE) The granulated product was manufactured by Yamaguchi Seisakusho Co., Ltd. 40 mm T die (lip width 30c
m) to a film with a thickness of 30μ and manufactured by Yasukawa Electric Co., Ltd.
The number of foreign matters having a diameter of 0.1 mm or more was measured with a FE counter. The measurement area was 30,000 cm ² , and the value was converted per 1000 cm ² . The results are shown in Table 2.

Comparative Example 1 The procedure of Example 1 was repeated, except that diethylene glycol dimethyl ether was not added in the pressure drop tank 2.

Examples 2 to 4 The same procedure as in Example 1 was carried out except that the addition amount of diethylene glycol dimethyl ether was changed in the pressure drop tank 2. The results are shown in Tables 1 and 2.

Comparative Examples 2 and 3 The procedure of Example 1 was repeated, except that the addition amount of diethylene glycol dimethyl ether was changed in the pressure drop tank 2. The results are shown in Tables 1 and 2.

When diethylene glycol dimethyl ether is not added or when the addition amount is less than that of the present invention, the effect of preventing FE is small, the product appearance has uneven gloss, and the product value is lost, and the DI and tensile elongation are significantly inferior. ing. Further, in Comparative Example 2, the catalyst activity of the polymerization (ii) was lowered and the polymerization hardly proceeded.

Examples 5 and 6, Comparative Examples 4 and 5 The procedure of Example 1 was repeated except that the gas phase hydrogen concentration in the polymerization (ii) was changed. When the MI of polymerization (ii) is lower than the range of the present application, FE increases and DI decreases, which is not preferable. On the other hand, when it is increased, it is inferior in that a large amount of soluble polymer is produced.

Examples 7 to 11 In Example 1, the type and amount of glycol ether was changed as shown in the table.

Comparative Examples 6 to 11 In Example 1, the electron donating compounds shown in the table were used instead of the glycol ether. All of them are significantly inferior to the glycol ether of the present application in their effects.

[Brief description of drawings]

FIG. 1 is a flow sheet showing steps for explaining the constitution of the present invention, and FIG. 2 is a flow sheet of a polymerization apparatus used in Examples of the present invention.

Claims (4)

[Claims] 1. A solid catalyst component (A) containing titanium and a general formula Al.
Stereotype in which an organoaluminum compound (B) represented by ▲ R ² _m ▼ X _3- m (wherein R ² represents a hydrocarbon group having 1 to 20 carbon atoms, and m represents a number of 3m> 1.5) is combined. In a continuous production method of a propylene-ethylene block copolymer by a multi-step process in which a regular catalyst and an inert solvent or propylene are used as a solvent and two or more polymerization vessels are connected to each other, as a first step, polymerization in one vessel is carried out. Using a vessel, ethylene / (ethylene + propylene) = 0 to 5% by weight of a monomer is supplied to continuously carry out the polymerization step (i) mainly containing propylene to obtain 60 to 95% by weight of the total amount of polymerization. As a second step, glycol ether (C) was added to the polymerization reaction mixture obtained in the first step as a second step, with respect to the titanium component in the catalyst component (A), Ti in (C) / (A) was 0.01 to Continuously add to 1.0 (mol / atom) Used subsequently 1 tank or of the polymerization vessel with 該被 addition polymerization reaction mixture, by supplying an ethylene / (ethylene + propylene) = 10 to 100 wt% of Moma,
A method comprising continuously carrying out a polymerization step (ii) containing a relatively large amount of ethyne rein to produce 5 to 40% by weight of the total polymerization amount. 2. A polymer obtained by the polymerizing step (i) comprising propylene as a main component and having a melt index (hereinafter referred to as MI [1]) and a relatively large amount of ethylene. The method according to claim (1), wherein the melt index (hereinafter referred to as MI [2]) has a relationship of logMI [1] / MI [2] =-1 to 3 (1). 3. The catalytic activity after the addition of the glycol ether (C) is 30 to 80% as compared with the catalytic activity before the addition.
The method according to claim (1), wherein the amount is 4. The method according to claim (2), which has a relationship of logMI [1] / MI [2] = 0 to 2 (2) in the formula (1).