JPH07680B2 - High melting viscoelasticity ethylene / propylene copolymer continuous production method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a continuous process for producing a high melt viscoelastic ethylene / propylene copolymer. More specifically, the present invention performs the polymerization step (i) mainly composed of propylene in the first to second or more tanks of three or more tanks connected in series, and the ethylene in the subsequent tanks after the third tank is relatively The present invention relates to the production method of carrying out the polymerization step (ii) used in a large amount.

The copolymer obtained by the method of the present invention has an impact strength superior to that of the equivalent product obtained by the known method, and is suitable for post-processing sheets, blow molding and injection molding.

[Conventional technology]

A sheet produced by processing and molding a known general-purpose polypropylene has the following drawbacks for post-processing. They are characterized in that the sheet droops quickly at the time of forming for secondary processing, the range of processing conditions is narrow, the molding efficiency is inferior, etc. The thickness of the sheet is likely to be non-uniform, and wrinkles are piled up easily. Therefore, only small molded products can be manufactured.

On the other hand, when the known general-purpose polypropylene is processed by the blow molding method, there are the following problems. That is, since the parison droops heavily during molding, the thickness of the molded product becomes uneven. For this reason, the blow molding method can be applied only to small molded products.If a high molecular weight polypropylene is used to prevent the above-mentioned sag, the melt fluidity is poor, the load during molding is increased, and the energy loss is increased. However, not only the risk of causing other mechanical troubles increases, but also the surface of the actually molded molded product is significantly roughened, and its commercial value is lost.

In order to improve the above-mentioned sheet moldability and blow moldability associated with the use of polypropylene, for example, Japanese Patent Publication No.
In JP-A-50-8848 and Japanese Patent Laid-Open No. 50-8848, polypropylene is mixed with low density polyethylene and the like. However, a molded article using such a mixture is liable to cause rough skin, and in order to prevent rough skin, strong kneading is required at the time of melting,
The practice of these inventions is limited in terms of kneader selection and power consumption. In addition, the invention product also has a problem of reduced rigidity. Further, JP-A Nos. 53-91954, 57-185336, 57
No. 187337 and No. 58-7439 propose a method of kneading polypropylenes having different molecular weights with a granulator or the like. However, molded articles from the mixture according to these inventions are more likely to have rough skin than those from the above-mentioned mixture of low density polyethylene, and the practice of these inventions is restricted in terms of the kneading method and the selection of the difference in molecular weight. It

In order to solve the above-mentioned problems related to the moldability of general-purpose polypropylene, many methods for broadening the molecular weight distribution of a target substance by a multi-stage polymerization method have been proposed. For example,
JP-A-57-185304, 57-190006, 58-7405,
58-7409 and 59-172507. According to the examples of these inventions, most of them generate polypropylenes having different molecular weights in multiple stages by a batch polymerization method.
The batch polymerization method has a drawback that the productivity per unit equipment is low as a commercial production method because the so-called idle time is generated, which is different from the polymerization reaction itself, such as the charging of raw materials and the withdrawal of products. is doing.

Further, in the inventions disclosed in JP-A-57-185304 and thereafter, a continuous polymerization method is also referred to, and when the stepwise production sequence is (a) a combination of a high molecular weight product and a low molecular weight product, It is preferable as a process because the necessary difference in molecular weight can be achieved simply by adding hydrogen in the latter stage of multi-step polymerization. On the contrary, in the case of (b) the combination of low molecular weight product → high molecular weight product, the low molecular weight polypropylene is used. After the production, before the production of the high molecular weight product, it is necessary to remove unnecessary hydrogen by depressurizing or degassing the inside of the tank holding the polymerization reaction mixture. (Proces
sability) is said to be inferior.

However, according to a follow-up examination by the present inventor, in the case of production in the order of high molecular weight product → low molecular weight product described as being preferable in the prior art, the melt flow rate (hereinafter referred to as MFR) value of the high molecular weight part is When it is low, there is a problem that measurement becomes difficult or impossible, which causes trouble in operation control. (Note. Viscosity [η] can be measured, but it takes time to measure it, so it is actually a means of operation control. Not the traditional method).

Furthermore, polypropylene produced in multiple stages in the order of high molecular weight → low molecular weight has an abnormally large difference in MFR value between the MFR value of the powder before granulation and the pellet obtained by granulation (Note. It has been found that there are problems in controlling the difference in the molecular weight of each stage and the control of the MFR value of the product as a multistage polymerization method.

On the other hand, crystalline polypropylene has excellent physical properties such as rigidity and heat resistance, but on the other hand, it has a problem of low impact strength, especially at low temperature, and its practical range is limited. In order to improve this drawback, many methods of block-copolymerizing propylene with ethylene or other α-olefin have been proposed. For example, Japanese Patent Laid-Open No. 50-
142652, 52-8094, 57-34112 and many others have been proposed. However, in these, after performing Polymerization 1 using propylene as a main component, Polymerization 2 using a monomer containing hydrogen in a relatively large amount except hydrogen is devised to broaden the molecular weight distribution.

Generally, when the multi-stage continuous polymerization method is adopted in the block copolymerization method, the residence time of each catalyst particle in each stage has a distribution (Note. It is considered that it is close to a complete mixing tank distribution). In addition, the content ratio of the polyethylene part (Note: a part containing a relatively large amount of ethylene) becomes a set of polymer particles which varies with time, and a quality defect occurs due to this non-uniformity.

In particular, in the method of the present invention described in detail later, since the molecular weight difference is imparted at each stage in the multi-stage polymerization step (i) mainly composed of propylene, when the known technique is adopted as it is, The difference in the molecular weight from particle to particle is magnified than in the case of ordinary block copolymerization, and the problem due to heterogeneity can be more significant.

Many methods for improving the problems of the above-mentioned known multi-stage continuous polymerization method have been proposed. For example, JP-A-58
-48916, 55-116716, 58-69215, etc., the slurry after leaving the polypropylene polymerization part (polymerization step 1) is classified by a cyclone, and fine particles are returned to the polypropylene polymerization part again. Although proposed, the effect of the classification based on the polymer particle size was not sufficient because it did not always match the residence time distribution. JP-A-57-195718,
In JP-A 58-29811, etc., the part of the catalyst that enters the polyethylene polymerization part (polymerization step 2) while the residence time is short by intermittently supplying the catalyst to the polymerization device and withdrawing the slurry from the polymerization device. Several methods for reducing the amount of the polymer have been proposed. These methods have a problem that the polymerization reaction becomes unstable.

Further, by treating the slurry discharged from the polypropylene polymerized portion with an electron-donating compound or the like in the same manner as in the embodiment (6) of the present invention described later, the residence time is shortly discharged and the catalyst particles are selectively discharged. Several methods of deactivating have also been proposed.

For example, in JP-A-57-145115 and JP-A-55-115417, various electron-donating compounds have been proposed, but compounds within the range used in Examples achieve the below-mentioned object of the present invention. Was not enough to

The present inventors proposed the invention of Japanese Patent Application No. 60-283728 based on the results of various studies in order to solve the above problems. However, the above-mentioned method has a problem that the process is rather complicated because four or more polymerization vessels are required and the reaction amount ratio and the polymerization conditions in each polymerization vessel are limited.

[Object of the Invention]

In view of the problems of the known and prior application related to the multi-stage continuous polymerization method of propylene-ethylene block copolymer, the present inventor conducted research to find an improved polymerization method for these problems, and found that the serial Polymerization with propylene as the main component was carried out in the first two or more polymerization vessels (ethylene content 0 to 5% by weight in the feed monomer), followed by the remaining one vessel. Polymerization with a relatively large amount of ethylene is performed in the above polymerization vessel (ethylene content in the feed monomer is 10 to 100% by weight), and the catalyst used and hydrogen as a molecular weight regulator are supplied to the first tank in their total amount. However, in the method in which the catalyst and hydrogen (excluding the amount consumed in the middle) are sequentially transferred together with the reaction mixture (slurry) to the second tank and thereafter, the continuous polymerization step mainly containing the propylene (I In the above, the molecular weight of the polymer produced in each polymerization vessel can be set at a practical level without installing special degassing by continuously extracting gas from the gas phase portion of the polymerization vessel after the second tank. The present invention has been completed by discovering that it can be adjusted to.

As is clear from the above description, the object of the present invention is to have good physical properties for sheets, blow molding and injection molding, and to stabilize ethylene / propylene block copolymerization capable of producing large molded articles. Another object of the present invention is to provide a continuous polymerization method of a high melt viscoelasticity ethylene / propylene copolymer which can be produced in Another object is to provide the copolymer produced by the method, and the other object is to
It will be clarified from the following description.

[Constitution / Effect of Invention]

The present invention has the following main constitution (1) and embodiment constitutions (2) to (4).

(1) In a method for continuously producing an ethylene / propylene copolymer using a Ziegler-Natta type catalyst, Using three or more polymerization vessels connected in series, first, in the two or more polymerization vessels including the first and second tanks, the weight ratio of ethylene to ethylene + propylene in the feed monomer was 0 to 5% by weight. A monomer is supplied to carry out a continuous polymerization step (i) mainly composed of propylene, and subsequently, ethylene and ethylene + propylene in the supplied monomer are fed to one or more tanks of the polymerization vessel not used in the step (i). Weight ratio is 10-100% by weight
The continuous polymerization step (ii) containing a relatively large amount of ethylene as compared with the previous step is carried out by supplying the above monomer, and b. The whole amount of the catalyst used was supplied to the first tank, and the supplied catalyst was sequentially polymerized with the polymerization reaction mixture through the second tank and thereafter, and was polymerized on the same catalyst solid in each stage of the polymerization reactor. After the additional formation of polymer, it is discharged from the final tank,
And c. In the continuous polymerization step (i) containing propylene as a main component, hydrogen gas is used as a molecular weight regulator, and the entire amount of the hydrogen gas is supplied to the first tank, and to the second tank and thereafter,
The residue consumed in each previous tank is the polymerization reaction mixture (slurry)
Transferred with In the continuous polymerization step (i) mainly composed of propylene, when the gas is continuously withdrawn from the gas phase part of the polymerization vessel after the second tank and the amount of the gas is V ₁ when the volume of the polymerization vessel is V ₁ ,
℃, 0.5V ₁ to 10V ₁ per hour in terms of 0kg / cm ² G, E. The polymerization amount in the polymerization step (i) is 60 to 60% of the total polymerization amount.
A continuous process for producing a high melt viscoelastic ethylene / propylene copolymer, which is characterized by being 95% by weight.

(2) In the continuous polymerization step (i) mainly composed of propylene, the molecular weights of the polymers produced in the first and last polymerization vessels are set so that the MFR value falls within the range of the following formula (1). The continuous production method according to item 1).

However, MFR _i : MFR of the polymer produced in the i-th polymerization vessel MFR _t : MFR of the polymer produced in the final polymerization tank in the continuous polymerization step (i) with propylene as the main component (3) Propylene as the main component In the continuous polymerization step (i), the gas extracted from the gas phase of each of the second and subsequent polymerization reactors is circulated to the first polymerization reactor for reuse, and the production according to (1) above. Law.

(4) As the organoaluminum compound (B) combined with the titanium-containing solid component (A) that constitutes the Ziegler-Natta catalyst, the general formula Al ▲ R ^l _m ▼ X _3-m (wherein R ₁ is a carbon number 1
~ 20 hydrocarbon groups, X represents a halogen atom, m represents a number of 3m> 1.5), and the continuous polymerization step (i) is carried out in the presence of an inert solvent or liquid propylene. And the glycol ethers (C) are added to the polymerization reaction mixture (slurry) after the step.
The titanium component in (A) is continuously added so that the concentration of Ti in (C) / (A) is 0.01 to 1.0 (mol / atom), and the continuous polymerization step (ii) is performed. The continuous production method according to item (1).

The configuration and effects of the present invention will be described in detail.

The catalyst used in the present invention is not particularly limited as long as it is a so-called Ziegler-Natta catalyst, but a catalyst based on a combination of a titanium compound and an organic aluminum compound is preferably used.

As the titanium compound, a titanium trichloride composition obtained by reducing titanium tetrachloride with hydrogen or metal aluminum or a titanium trichloride composition is further crushed and activated by a ball mill, a vibration mill or the like, and The activated compound treated with an electron donor, titanium tetrachloride reduced with an organoaluminum compound, and subsequently various treatments (for example, a titanium trichloride composition obtained by crystal transition by heating in titanium tetrachloride, an electron donating property). Titanium trichloride composition obtained by treatment with a compound or an electron-accepting compound and highly activated titanium trichloride, etc., a so-called supported type obtained by supporting titanium tetrachloride on a carrier such as magnesium chloride A catalyst such as a catalyst generally used for stereoregular polymerization of propylene can be preferably used.

Examples of the organoaluminum compounds used in the present invention, a compound represented by the general formula _{AlR n R 'n' X 3-} (n + n ') can be preferably used. In the formula, R and R'represent a hydrocarbon group such as an alkyl group and an aryl group, X represents halogen such as fluorine, chlorine, bromine and nitrogen, and n and n'are 0 <n + n '.
Represents any number of three. Specific examples thereof include trialkylaluminums and dialkylaluminum monohalides, and these may be used alone or in combination of two or more. Further, an electron donor generally used as the third component of the catalyst can be used in combination with the titanium compound and the organoaluminum compound.

As the polymerization method, slurry polymerization using a hydrocarbon such as propane, hexane, heptane, octane, benzene, or toluene as a solvent, or bulk polymerization using propylene as a solvent can be used.

The polymerization vessel is preferably a tank type, and in the polymerization step (i) mainly composed of propylene, two or more polymerization vessels are connected in series to transfer the polymerization reaction mixture (slurry) between the polymerization vessels. Continuously extracts a part of the slurry (liquid phase) and continuously transfers it to the next polymerization vessel.

The polymerization step (ii) containing a relatively large amount of ethylene includes a first tank for continuously receiving the polymerization reaction mixture from the final polymerization vessel of the first step, and preferably one or more tank type polymerization vessels are used. Then, a predetermined ratio of ethylene and propylene is supplied to carry out continuous polymerization.

In the method of the present invention, the catalyst used is the above-mentioned first catalyst.
Through the second step, only the polymerization vessel in the first tank is supplied. Thus, the supplied catalyst solids, together with other polymerization reaction mixtures, successively pass through the polymerization vessel as in the second tank and the third tank, while the polymer formed in each polymerization vessel is formed on the solid particles. It is withdrawn from the final polymerization vessel in the state of being covered.

If a new catalyst is supplied in the second and subsequent tanks, a polymer having a significantly different MFR from that in the first tank is produced on the solid particles of the catalyst, so granulation after product acquisition It is difficult to mix them uniformly even in the process, and a molded product from such a product is not preferable because it causes a defective product appearance such as fish eyes.

In the method of the present invention, hydrogen is used as a molecular weight regulator. And, like the above-mentioned catalyst, the hydrogen is supplied only to the polymerization vessel in the first tank throughout the entire process. The supply to the first tank may be performed for either the gas phase or the liquid phase in the tank.

However, the hydrogen is supplied from each of the preceding tanks to the second and subsequent tanks in a form of being dissolved in the above-mentioned polymerization reaction mixture, that is, in a solution state. Therefore, when supplying hydrogen to the liquid phase (polymerization reaction mixture) in the first tank, it is necessary to take care so that undissolved hydrogen is not transferred as bubbles to the second tank. If hydrogen entrained in the liquid phase in a bubble state is sent to the next tank (this is not the case even after the second tank depending on the agitation situation), degas the second tank and later. The amount of gas to be extracted when performing is larger than that in the case where hydrogen bubbles are not present in the liquid phase, and the extraction efficiency decreases. If the volume of gas withdrawn from the polymerization vessel vapor phase is withdrawn polymerizer was V _1, 0 ° C., 1 hour per at 0 kg / cm ² G in terms of a preferred 0.5V ₁ to 10V _1, process gas By chromatography, etc.
A method is preferable in which the control valve continuously removes gas so that the hydrogen concentration in the gas phase maintains a target concentration while measuring the hydrogen concentration in the gas phase. Depending on the degree of hydrogen withdrawal, the MFR of the polymer produced in the tank can be reduced to a preferable level as compared with the case where the hydrogen is not withdrawn. All or part of the extracted gas can be circulated to the first tank.

In the method of the present invention, propylene, ethylene and a solvent are supplied to each polymerization tank as needed. Solvent replenishment is
This is because the slurry concentration in each polymerization tank is appropriately maintained according to the increasing amount of polymer. By carrying out the polymerization step (i) of the present invention as described above, the molecular weight of the polymer produced in each tank gradually increases from the first tank to the second tank and from the second tank to the third tank. However, a sufficient molecular weight difference can be imparted as a whole.

The polymerization pressure of the propylene-based polymerization step (i) of the present invention is not limited, but normally atmospheric pressure to 50 kg / cm ² G is used. The polymerization pressure of each polymerization vessel according to the method of the present invention connected in series may be the same or different from each other.

The polymerization temperature to be carried out in the continuous propylene-based polymerization step (i) of the present invention is not limited, but may be from 20 to 100
C, preferably 40-80C.

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
~ 10 hours. The above-mentioned various polymerization conditions, that is, pressure, temperature, residence time, etc., can be easily achieved by selecting the desired quality of polypropylene, the catalyst used, and the like. In addition, for the transfer of the slurry between the polymerization reactors connected in series, the usual pumping, differential pressure transportation and other methods can be adopted, and there is no particular limitation.

Ethylene according to the present invention obtained as described above and through the polymerization step (ii) according to the method of the present invention in the latter stage.
MFR of the propylene copolymer is usually 0.01 to 100, especially for sheet molding, for blow molding, the MFR value,
0.05 to 10, preferably 0.10 to 5.0 is used.

Incidentally, it is preferable that the difference in molecular weight between the polypropylenes produced in the respective polymerization vessels in the polymerization step (i) connected in series is within the range of the following formula [1] when expressed as an MFR value.

However, MFR _i ; MFR of the polymer produced in the i-th polymerization vessel MFR _t ; MFR of the polymer produced in the final polymerization vessel in the continuous polymerization step (i) mainly composed of propylene If the value on the left side is less than 2.0, the high melt viscoelasticity of the polymer of the present invention tends to be insufficient, which is not preferable.

The composition of the monomer supplied to the polymerization step (i) of the present invention is To implement. When the amount of ethylene used exceeds 5% by weight, the copolymer finally obtained tends to deteriorate in physical properties such as rigidity and heat resistance, which are characteristics of polypropylene, which is not preferable. As the third component, 1-butene, 4-methylpentene-1, styrene, non-conjugated dienes or the like can be added as the third component independently of ethylene in an amount of 0 to 10% by weight of propylene.

The ratio of the amount of polymerization in the polymerization step (i) of the present invention is 60 to 95% by weight, preferably 75 to 90% by weight, based on the ethylene / propylene copolymer which is the final product, and exceeds the above upper limit. In the polymerization step (i), the rigidity of the product block copolymer is lowered, and when the polymerization amount is less than the lower limit, the low temperature impact strength of the copolymer is insufficiently improved, but the above range is not satisfied. It can be selected according to the quality target.

The effluent slurry after completion of the polymerization step (i) of the present invention is continuously transferred to the first polymerization vessel of the polymerization step (ii) to contain the ethylene of the present invention in a relatively large amount. I do.

In the polymerization step (ii), ethylene is used at least twice (10% by weight) as compared with the polymerization step (i). In the polymerization step (ii), it is not essential to use two or more polymerization vessels, but the polymerization amount in the step (ii) is, for example, 20-40.
In the case of a relatively large amount such as weight%, by using two or more polymerization vessels, it is possible to balance the production amount of the polymer among the polymerization vessels.

Further, in the polymerization step (ii), the ethylene concentration in the supplied monomer is significantly different from that in the step (i), so the slurry discharged from the polymerization step (i) is once received in the depressurization tank and degassed (Note. After removing the dissolved propylene, ethylene and hydrogen), it can be fed to the polymerization vessel in the polymerization step (ii). In the polymerization step (ii), the polymerization is performed in the same manner as in the polymerization step (i) except that a monomer having a predetermined ethylene / ethylene + propylene weight ratio and necessary amounts of hydrogen and a solvent are supplied.

In a preferred embodiment of the method of the present invention, a specific glycol ether (hereinafter sometimes referred to as additive C) is added as a catalyst third component in the polymerization step (ii).
The purpose of the addition is to directly reduce the activity of the added catalyst to a considerable extent, but in practice, the short-pass catalyst (catalyst with high activity) is selectively deactivated to The homogenization of the polymer produced in the two steps.

Examples of the glycol ethers include ethylene glycol monoalkyl ether, ethylene glycol dialkyl ether, propylene glycol monoalkyl ether and propylene glycol dialdialkyl ether. Specific examples thereof include 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, and a condensate of glycol. Diethylene glycol monoalkyl ethers, diethylene glycol dialkyl ethers, triethylene glycol monoalkyl ethers, triethylene glycol dialkyl ether, tetraethylene glycol monoalkyl ethers, tetraethylene glycol dialkyl ether,
Dipropylene glycol monoalkyl ether, dipropylene glycol dialkyl ether, tripropylene glycol monoalkyl ether, tripropylene glycol dialkyl ether, tetrapropylene glycol monoalkyl ether, tetrapropylene glycol dialkyl ether, polyethylene glycol monoalkyl ether, polyethylene glycol dialkyl ether, Examples of the alkyl group in polypropylene glycol monoalkyl ether, polypropylene glycol dialkyl ether and the like include chain hydrocarbons having 1 to 20 carbon atoms. Further, glycol ethers obtained by reacting ethylene oxide and propylene oxide can also be used. The amount of these ethers (C) used is based on titanium of the titanium-containing catalyst component (A).
(C) / (A) Ti = 0.01 to 1.0 (molar ratio) is used. Also, the effect varies depending on the type of glycol ether, but the catalytic activity when glycol ether is not added is
It is preferable to add (C) within the range of 30 to 80% as 100%. If the amount added is too large, the effect of deactivating the short-pass catalyst is great, but the overall catalyst activity is also greatly reduced, which is not economically preferable and the polymerization (i)
And the control of the polymerization amount ratio of the polymerization (ii) is limited, which is not preferable. On the other hand, when the amount of (C) is too small, the effect of selectively deactivating the short-pass catalyst becomes insufficient, which is not preferable.

It is not clear why the glycol ethers used in the present invention have remarkably excellent effects as compared with conventionally known ketones, amines, amides, alkyl ethers, carboxylic acid esters, and halogen compounds. However, it reacts with the organoaluminum compound (B) to form a complex insoluble in an inert solvent, which makes it difficult to oppose the catalyst inside the polymerized particles, so that the action of preferentially deactivating the short-pass catalyst is remarkably exhibited. Can also be considered. That is, it is assumed that necessary conditions are the formation of a liquid complex insoluble in an inert solvent and the viscosity that the complex does not easily penetrate into the inside of polymer particles.

The addition of the above glycol ethers in the polymerization step (ii) is preferably performed on the slurry from the degassed step (ii) above prior to initiating the polymerization of the polymerization step (ii), but to the polymerization vessel. You may add directly. The addition method of the glycol ether may be continuous or intermittent, but in the latter case, the addition interval is within 1/8 of the residence time of the slurry in the polymerization vessel in the polymerization step (ii). If this interval is long, the effect of the additive C becomes insufficient.

General polymerization conditions in the polymerization step (ii) of the method of the present invention are as follows. That is, the polymerization temperature is 20 ~ 80 ℃,
The temperature is preferably 40 to 70 ° C., the pressure is 0 to 50 kg / cm ² G, and the average residence time is 20 minutes to 10 hours.

Hydrogen is usually used to control the molecular weight, and the amount of hydrogen used is 1 to 40 mol% as the gas phase concentration in the polymerization vessel.

The ratio of the monomers used is 10 to 100% by weight, preferably 20 to 70% by weight in terms of the weight ratio of ethylene and ethylene + propylene, and the polymerization amount is based on the ethylene / propylene block copolymer finally obtained, It is 5 to 40% by weight, preferably 10 to 25% by weight. Also in this polymerization step (ii), a small amount of other α-
It is also possible to use an olefin or a non-conjugated diene together.

The main effects of the method of the present invention detailed above can be summarized as follows.

First, the ethylene / propylene copolymer to be the method of the present invention has a wider molecular weight distribution than conventional ones,
The fluidity at the time of extrusion molding is good, and as a result, the amount of extrusion by the extruder can be increased and the power consumption can be saved. Similarly, since it has characteristics such as excellent fluidity at the time of injection molding, excellent results can be obtained in terms of quality and processing efficiency of molded articles obtained in applications in various molding fields.

Secondly, the method of the present invention has a wide range of operating conditions of each polymerization vessel as a constant multi-step polymerization method, and the control of the polymerization process and the adjustment of the polymerization conditions can be carried out very easily.

As described above, the present invention can achieve the above-mentioned effects, which are not possible by the known art, by adopting specific polymerization conditions and using additives (embodiments).

Hereinafter, the present invention will be described with reference to examples, but they do not limit the present invention.

The analysis and measurement methods in the examples were as follows.

MFR (g / 10min): ASTM D-1238, 230 ℃, 2.16kg load Ethylene content (wt%): Infrared absorption spectrum method Weight ratio of polymerization (i) and polymerization (ii) (wt / wt): Ethylene / A copolymer with varying reaction ratio of propylene was prepared in advance, a calibration curve was prepared by infrared absorption spectroscopy using this as a standard sample, and the reaction amount ratio of ethylene / propylene of polymerization (ii) was calculated. Calculated from the combined ethylene content (above).

Calculation of MFR of polymer produced in each polymerizer: MFR ₁ ; MFR of polymer polymerized in first polymerizer (* 1) MFR ₂ ; MFR of polymer polymerized in second polymerizer (* 1) MFR _{1 + 2} ; MFR W ₁ of all polymers produced in the first and second polymerization vessels; ratio of all polymers produced in the first polymerization vessel in the polymerization step (i) (* 2) W ₂ ; polymerization step ( Proportion (* 2) W ₁ + W ₂ = 1.0 * 1 of the total polymer produced in the second polymerization vessel in i); sampled and measured.

* 2: The content of titanium in the polymer was analyzed and calculated by the fluorescent X-ray method.

MFR _{2 was} calculated by the following relational expression.

Physical properties of sheet molded products: Young's modulus (kgf / mm ² ); ASTMD-882 Punching impact strength (kgf / mm ² ); ASTMD-781 Heating behavior; Chisso method (below) For evaluation, the sheet was fixed in a 40 cm × 40 cm frame, placed in a constant temperature room at 200 ° C., and the following physical properties were measured. That is, a) drooping amount (mm) in the early stage of heating the sheet, b) maximum return amount (%): {1/150
X (150-droop amount at maximum recovery (mm) x 100}) and
C) Hold time (seconds) from maximum recovery to restart of drooping
Is.

Sheet appearance; visual inspection ・ Relationship between polymerizer capacity and gas phase gas discharge amount Polymerizer capacity (200 l) = V ₁ (unit l) The amount of gas extracted from the polymerizer (gas phase gas discharge amount) is measured with a flow meter. The values converted to 1 atm and 0 ° C. (indicated by Nl) are shown in Table 1 below.

Example 1 1) Preparation of catalyst n-hexane 6 l, diethylaluminum monochloride (DEAC) 5.0 mol, diisoamyl ether 12.0 mol 25
Reaction mixture (I) (diisoamyl ether / DEAC molar ratio 2.4) by mixing at ℃ for 5 minutes and reacting at the same temperature for 5 minutes.
Got 40 mol of titanium tetrachloride was placed in a reactor purged with nitrogen and heated to 35 ° C, and the whole amount of the above reaction product solution (I) was added dropwise to this in 180 minutes, and then kept at the same temperature for 30 minutes and then raised to 75 ° C. The mixture was warmed to react for another 1 hour, cooled to room temperature, the supernatant was removed, 30 l of n-hexane was added, and the operation of removing by decantation was repeated 4 times to obtain 1.9 kg of a solid product (II).

While suspending the whole amount of this (II) in 30 l of n-hexane, at 20 ° C, 1.6 kg of diisoamyl ether and 3.5 kg of titanium tetrachloride were added at room temperature for about 5 minutes and reacted at 65 ° C for 1 hour. Let 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, the mixture was stirred for 15 minutes, and allowed to stand to remove the supernatant.
After repeated times, the solid product (II
I) got.

2) Preparation of catalyst A tank having an internal volume of 50 liters was charged with 40 liters of n-hexane, 850 g of diethylaluminum chloride, 360 g of the above solid product and 3.8 g of methyl paratoluate, and then 180 g of propylene gas while maintaining stirring at 30 ° C. It was supplied with H for 2 hours and pretreated.

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

To the polymerization vessel 1, n-hexane 26 l / H / hour, catalyst slurry 120 ml
/ H was continuously supplied. Propylene was supplied to each of the polymerization vessels 1 and 2 so that the temperature was 70 ° C. and the pressure was 6 kg / cm ² GG and 8 kg / cm ² G, respectively.

Also, 500 Nl / H of gas was continuously discharged from the polymerization vessel (2). Each polymerizer was withdrawn by a control valve so that the liquid level was 80%. The gas from the degassing tank was compressed by a compressor and circulated to the polymerization vessel (1). The reaction amount and MFR analysis value of each polymerization vessel were as shown in Table 1.

The slurry containing the polymer particles extracted from the polymerization vessel (2) was degassed in the degassing tank (1) at 60 ° C. and 0.5 g / cm ² G, and transferred to the polymerization vessel (3) by the pump 6. Hydrogen concentration in the vapor phase of the polymerization vessel (3) is 10 mol%, temperature is 60 ° C, and ethylene is 500 g / H.
Propylene and hydrogen were supplied so that the gas phase gas composition was ethylene / (ethylene + propylene) = 0.40. The slurry discharged from the polymerization vessel (3) is a degassing tank (2)
After further deactivating the catalyst with methanol, the mixture was neutralized with caustic soda water, washed with water, separated, and dried to obtain a white copolymer powder at about 5.5 kg / H. The analytical values are shown in Table 1.

4) Granulation method and sheet molding method 15 kg of the white polymer powder obtained above was mixed with BHT (2.6-
t-Butyl-P-cresol) 15g, Irganox 1010 (Tetrak
is [Methylene (3.5-di-t-butyl-4-Hydrocinnam
ate] methane) 7.5g, Calcium stearate 30g 40m
Granulation was performed using an mφ granulator. Then, granulate the product with a diameter of 50 mm
Processed at 225 ℃ with an extrusion machine, width 60cm, thickness 0.4mm
Was prepared, and the physical properties of the sheet were measured by the methods described above. The results are shown in Table-2.

Comparative Example 1 The same procedure as in Example 1 was carried out except that gas phase gas was not discharged from the polymerization vessel (2). The obtained polymer was inferior in the heating behavior of the sheet.

Comparative Example 2 In Comparative Example 1, the concentration of the gas phase H ₂ in the polymerization reactors (1) and (2) was made the same by supplying hydrogen to each weighing device. Also in this case, the heating behavior of the sheet was significantly inferior.

Examples 2 to 4 and Comparative Examples 3 to 4 Table 1 shows gas phase hydrogen concentration and exhaust gas amount in Example 1.
It carried out by changing as follows. When the amount of exhaust gas was insufficient, the heating behavior was inferior, and when the amount was too large, the appearance of the sheet was poor (due to uneven fluidity).

Example 5 In Example 1, diethylene glycol dimethyl ether (a) was added to the titanium in the solid catalyst in the degassing tank (1).
It was added so that a / Ti = 0.3 (molar ratio), and the hydrogen concentration in the gas phase of the polymerization vessel (3) was 2.0 mol%. A remarkable improvement in low temperature punching impact strength was observed.

Comparative Example 5 In Example 5, the addition of diethylene glycol dimel ether was omitted. In the appearance of the sheet, FE was frequently generated and punching impact strength was reduced.

Example 6 In Example 5, methyl paratoluate was fed to the polymerizer (1) at 1 g per 1 g of solid product in the catalyst slurry. The supply amount of the catalyst slurry was changed to 240 ml / H. As shown in the table, when the catalyst system is used, the Young's modulus is remarkably increased and the heating behavior is improved.

Comparative Example 6 The procedure of Example 6 was repeated except that the addition of diethylene glycol and dimethyl ether was omitted. Frequent occurrence of FE,
The punching impact strength decreased.

[Brief description of drawings]

FIG. 1 is a flow sheet of a polymerization apparatus used in the examples of the present invention. In the figure, 1: polymerization vessel (1) (200l) 2: polymerization vessel (2) (200l) 3: degassing tank (1) (100l) 4: polymerization vessel (3) (200l) 5: degassing tank ( 2) (100l) 6: Pump 7: Control valve.

Claims (4)

[Claims] 1. A method for continuously producing an ethylene / propylene copolymer using a Ziegler-Natta type catalyst, comprising: a. Using three or more polymerization vessels connected in series, first, in the two or more polymerization vessels including the first and second tanks, the weight ratio of ethylene to ethylene + propylene in the feed monomer was 0 to 5% by weight. A monomer is supplied to carry out a continuous polymerization step (i) mainly composed of propylene, and subsequently, ethylene and ethylene + propylene in the supplied monomer are fed to one or more tanks of the polymerization vessel not used in the step (i). Weight ratio is 10-100% by weight
The continuous polymerization step (ii) containing a relatively large amount of ethylene as compared with the previous step is carried out by supplying the above monomer, and b. The whole amount of the catalyst used was supplied to the first tank, and the supplied catalyst was sequentially polymerized with the polymerization reaction mixture through the second tank and thereafter, and was polymerized on the same catalyst solid in each stage of the polymerization reactor. After the additional formation of polymer, it is discharged from the final tank,
And c. In the continuous polymerization step (i) containing propylene as a main component, hydrogen gas is used as a molecular weight regulator, and the entire amount of the hydrogen gas is supplied to the first tank, and to the second tank and thereafter,
The residue consumed in each previous tank is the polymerization reaction mixture (slurry)
Transferred with In the continuous polymerization step (i) mainly composed of propylene, when the gas is continuously withdrawn from the gas phase part of the polymerization vessel after the second tank and the amount of the gas is V ₁ when the volume of the polymerization vessel is V ₁ ,
℃, 0.5V ₁ to 10V ₁ per hour in terms of 0kg / cm ² G, E. The polymerization amount in the polymerization step (i) is 60 to 60% of the total polymerization amount.
A continuous process for producing a high melt viscoelastic ethylene / propylene copolymer, which is characterized by being 95% by weight. 2. A continuous polymerization step (i) comprising propylene as a main component, wherein the molecular weights of the polymers produced in the first and last polymerization vessels are MFR values within the range of the following formula (1): The continuous manufacturing method according to claim (1). Where MFR _i : MFR of the polymer produced in the i-th polymerization vessel MFR _t : MFR of the polymer produced in the final polymerization tank in the continuous polymerization step (i) mainly composed of propylene 3. A patent characterized in that in the continuous polymerization step (i) mainly comprising propylene, the gas withdrawn from the gas phase of each of the second and subsequent polymerization reactors is circulated to the first polymerization reactor and reused. The manufacturing method according to claim (1). 4. An organoaluminum compound (B) in combination with a titanium-containing solid component (A) constituting a Ziegler-Natta catalyst, represented by the general formula Al ▲ R ^l _m ▼ X _3-m (wherein R ¹ is a carbon number 1). ~ 20 hydrocarbon groups, X represents a halogen atom, m represents a number of 3m> 1.5), and the continuous polymerization step (i) is carried out in the presence of an inert solvent or liquid propylene. And the glycol ethers (C) are added to the polymerization reaction mixture (slurry) after the step.
Patent to carry out continuous polymerization step (ii) by continuously adding to the titanium component in (A) so that the concentration of Ti in (C) / (A) is 0.01 to 1.0 (mol / atom) The continuous manufacturing method according to claim (1).