JPH1171412A - Preparation of ethylene copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ethylene copolymer preparing process inhibiting the occurrence of copolymn. of a high ethylene fraction. SOLUTION: In feeding ethylene in the gas phase to a polymn. vessel and copolymerizing it in the liquid phase with a comonomer, the ethylene is fed into a polymn. liquid under such a condition that a gel formation parameter defined in the following equation is made to Gel formation parameter = M/P. wherein M: absorbed ethylene amount per unit vol. of polymn. liquid/the number of blowing tubes (unit: kg/s/m3/tube), P: dispersion force in the periphery of a gas feeding hole in the polymn. liquid unit vol. (that is an inverse number of the time necessary for 100-fold dilution of the ethylene gas introduced into the polymn. liquid) (unit: l/s/m<3> ).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an ethylene copolymer, and more particularly to an ethylene copolymer which has low compatibility with a target ethylene copolymer and suppresses formation of a copolymer having a high ethylene fraction. The present invention relates to a method for producing a united product.

[0002]

BACKGROUND OF THE INVENTION As a method for producing an ethylene / α-olefin copolymer, a solution polymerization method using a tank-type stirring polymerization device or the like is known. Solution polymerization is also called homogeneous polymerization because the polymer is completely dissolved in the solvent, and is suitable for producing high-quality polymers. However, on the other hand, since a large amount of solvent is contained, the polymerization reactor, the step of removing the solvent, the solvent purification step, and the like become large, and it is pointed out that the cost tends to be high.

In recent years, however, there has been a demand for a method for producing a polymer at a higher polymer concentration in order to produce the solution at a low cost by solution polymerization. That is, when the polymer is produced at a high polymer concentration, the solvent used per polymer is reduced, so that the polymerization vessel, the desolvation step, the solvent purification step, and the like can be miniaturized. However, when the production is performed at a high polymer concentration, the viscosity of the polymerization solution increases, and various disadvantages occur. For example, in the case of producing an ethylene / α-olefin copolymer by a solution polymerization method using a tank-type stirring polymerization device, a copolymer having a high ethylene fraction (high ethylene gel) is likely to be generated as the solution viscosity increases. . When a film is formed from the ethylene / α-olefin copolymer containing high ethylene gel, poor appearance such as fish eyes may occur. For this reason, it is necessary to perform the polymerization in a state where the solution viscosity in the polymerization vessel is low, or the productivity is insufficient,
In order to increase the solution viscosity, a step for removing the high ethylene gel had to be provided.

Under such circumstances, the present inventors have conducted intensive studies. As a result, since ethylene gas is supplied into the liquid phase, ethylene dispersion near the supply port becomes insufficient, and the ethylene concentration becomes high locally. It has been found that high ethylene gel is formed by the formation of the high ethylene gel. The present inventors have further studied, when designing or controlling the polymerization conditions so that the value of the gel formation parameter set from the viewpoint of ethylene dispersion is not more than a specific value, when the solution viscosity is high The present inventors have found that the polymer can be produced without generating a gel even after polymerization, and have completed the present invention.

By the way, a polymerization reactor for polymerizing ethylene and α-olefin in a gas-liquid coexistence state in the presence of ethylene, α-olefin and a polymerization catalyst, an extraction pipe for extracting a gas phase of the polymerization reactor to the outside of the polymerization reactor, A heat exchanger for cooling the extracted gas phase to remove polymerization heat, a gas-liquid separator for separating condensed liquid condensed by the heat exchanger and a non-condensed gas phase, and a gas-liquid separator There is a polymerization facility having a supply device for re-supplying the condensed liquid and the uncondensed gas phase to the polymerization vessel.

For example, the polymerization equipment shown in FIG.
3, a polymerization vessel 41 for polymerizing ethylene and α-olefin in a solution state, a gas injection nozzle 42 for supplying raw materials such as ethylene A and propylene B to the polymerization vessel 41,
A piping device 44 for guiding the gas phase of the polymerization reactor 41 from the polymerization reactor 41 to the outside, a heat exchanger 45 for cooling the extracted gas phase (mixed gas) to remove heat of polymerization reaction, and a condensate generated by cooling. Gas-liquid separator (for example, a drum) for separating the mixed gas into a non-condensed mixed gas and a non-condensed mixed gas
46, a supply pipe 49a for returning non-condensable gas to the polymerization reactor 41 and a blower 47, and a supply pipe 49 for returning condensed liquid to the polymerization reactor 41.
b and a pump 48.

The supply pipe 49a is connected to a supply pipe 50a for supplying ethylene (gas) A as a raw material. Furthermore,
The piping device 44 is connected to a supply pipe 52a that supplies propylene (liquid) B as a raw material. The pump 53 pumps propylene B to the piping device 44 under pressure. Moreover,
The supply pipe 49b is connected to a supply pipe 51a for supplying a catalyst (for example, a Ziegler catalyst) C. Further, the polymerization vessel 41 is connected to a supply pipe 54a for supplying a solvent (for example, a hexane solvent) D.

Next, using the polymerization equipment shown in FIG. 6, ethylene A and propylene B are used as raw materials,
The case where the homogeneous polymerization is carried out with the Ziegler catalyst C and the hexane solvent D in the liquid phase of will be described.

When the raw materials, ethylene A and propylene B, are supplied, the polymerization reactor 41 stirs and polymerizes ethylene A and propylene B using a stirrer 43. A polymer (polymer solution) E is produced. During the polymerization, the hexane solvent D is continuously supplied from the supply pipe 54a, and the polymerization catalyst C is continuously supplied to the polymerization reactor 41 from the supply pipe 51a.

[0010] In the polymerization reaction, heat of polymerization is generally generated, so that a heat exchanger 45 is required as a cooling means for removing the heat. In order to remove the polymerization heat, the gas phase (mixed gas) of the polymerization vessel 41 is withdrawn, cooled by the heat exchanger 45, and the cooled mixed gas (and condensed liquid, if partially condensed) is discharged to the polymerization vessel 41. In many cases, it is implemented by circulating through 41. When such a method is used, the mixed gas is withdrawn from the polymerization vessel 41 by a piping device 44,
Cooling is performed by the heat exchanger 45, and the condensate generated by the cooling and the remaining non-condensable gas are separated using the drum 46.

Therefore, the supply pipe 49a extracts the non-condensable gas from the upper portion of the drum 46 by the negative pressure of the blower 47, and sends the non-condensable gas to the polymerization reactor 41 through the gas blowing nozzle 42 by the pressurized air of the blower 47. I do.

On the other hand, the supply pipe 49 b draws a condensate (including the polymerization solution, the hexane solvent D and the raw material propylene B) from the bottom of the drum 46 by the negative pressure of the pump 48, and The condensate is pumped to the polymerization vessel 41. As described above, the mixed gas is extracted to the outside of the polymerization vessel 41, cooled and circulated, whereby the polymerization is continuously performed while removing the polymerization heat generated in the polymerization vessel 41.

At the time of polymerization, ethylene A (gas) supplied from the gas injection nozzle 42 of the polymerization reactor 41 is dissolved and absorbed in the liquid phase while being dispersed as bubbles by stirring or the like, and is diffused into the liquid phase to form active species. Upon contact with a certain catalyst, it is used for polymerization and consumed. At this time, it is desirable that the ethylene concentration in the liquid be constant at any position of the polymerization vessel 41.

However, the diffusion rate of ethylene present as bubbles is slower than the diffusion rate of ethylene dissolved in the liquid, and near the supply tip of the gas injection nozzle 42, ethylene has a high concentration in the liquid phase. Existing situations tended to occur.

[0015] In such a high-concentration portion of ethylene, a high-ethylene gel (for example, a homopolymer) is generated.
The compatibility with the α-olefin copolymer was poor, so that it was liable to become a foreign substance in the product called a gel component.

In particular, when a highly active metallocene catalyst is used as a catalyst, an ethylene homopolymer is rapidly generated at an interface of ethylene gas bubbles fed from the gas injection nozzle 42, and a large amount of insoluble polymer is generated. Generated
Fisheye was the cause.

In order to suppress the production of the insoluble polymer, there is known a method of reducing the production amount of the polymerization vessel 41 and improving the diffusion of ethylene. However, this has caused a problem such as a decrease in production. For this reason, it has been desired to develop a polymerization method that prevents the generation of high ethylene gel during polymerization, makes the polymerization reaction in the polymerization vessel uniform, and efficiently performs the polymerization reaction.

[0018]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and has as its object to provide a method for producing an ethylene copolymer in which high ethylene gel is hardly produced.

[0019]

SUMMARY OF THE INVENTION The method for producing an ethylene copolymer according to the present invention is characterized in that, when ethylene is supplied to a polymerization reactor in a gaseous state and copolymerized with a comonomer in a liquid phase, a gel formation parameter defined by the following equation is obtained. Is characterized in that ethylene is supplied to the polymerization solution under the condition that is not more than 1 × 10 ⁻⁴ .

Gel formation parameter = M / PM where M is the amount of ethylene absorbed per unit volume of the polymerization solution / the number of blowing tubes (unit: kg / s / m ³ / number) P is the dispersion near the gas supply port in the unit volume of the polymerization solution Force (reciprocal of the time required to dilute the ethylene gas introduced into the polymerization solution by 100 times) (unit: 1 / s / m ³ ) Suitable for polymerization of 1 poise or more.

Further, the present invention is suitable for producing an ethylene copolymer having a viscosity of 1 poise or more in a polymerization solution for solution polymerization and an ethylene content of 40 to 99 mol%. Further, in the method for producing an ethylene copolymer of the present invention, when ethylene is supplied to a polymerization vessel in a gaseous state and copolymerized with a comonomer in a liquid phase, a gel formation parameter defined by the above formula is 1 × 10 It is characterized in that polymerization conditions are controlled so as to be a value satisfying ^-4 or less.

[0022]

DETAILED DESCRIPTION OF THE INVENTION The method for producing an ethylene copolymer according to the present invention will be specifically described below.

In the present invention, when ethylene is supplied to the polymerization vessel in a gaseous state and copolymerized with a comonomer in a liquid phase, ethylene is added to the polymerization solution under the condition that the gel formation parameter is 1 × 10 ⁻⁴ or less. Supplying.

In the present invention, for example, a polymerization vessel equipped with a stirrer as shown in FIG. 1 is used. FIG. 1 is a schematic view showing an example of a tank type polymerization vessel to which the present invention can be applied. In the figure, reference numeral 1 denotes a polymerization vessel provided with a stirrer 5.
, An ethylene gas is supplied from a blowing pipe 10 having a gas blowing nozzle at the tip, a solvent is supplied from a supplying pipe 11, and a liquid α-olefin is supplied from a supplying pipe 17. Note that a plurality of blow-in tubes 10 may be provided. Ethylene is supplied from the supply pipe 16 to the circulation line 12, and hydrogen for controlling the molecular weight can be supplied from the supply pipe 16. The catalyst may be supplied from a comonomer supply pipe together with the comonomer, or may be supplied by providing a separate supply pipe. The polymerization vessel 1 may have an external cooling device using a gas circulation system to remove polymerization heat. The ethylene gas in the gas phase inside the polymerization reactor 1 and the vaporized α-olefin and the solvent are discharged from the polymerization reactor 1 through the circulation line 12 and then introduced into the heat exchanger 2 where the ethylene gas and the liquefied α-olefin Are introduced into the gas-liquid separator 3. The liquid phase part (mainly α-olefin and solvent) separated by the gas-liquid separator 3 is supplied to the polymerization reactor 1 again from the supply pipe 13. The gas phase (mainly ethylene) is introduced into the blowing pipe 10 through the supply pipe 14 and the blower 4, and is supplied to the polymerization reactor 1 again. The produced polymer is continuously discharged from the discharge pipe 15 together with the solvent, unreacted ethylene and α-olefin, introduced into the heat exchanger 19 via the pump 18 and heated, and then guided into the hopper 20, where the solvent and Unreacted monomers are separated by evaporation to obtain a polymer.

The tank type polymerization reactor shown in FIG. 1 is an example of a polymerization reactor to which the present invention can be applied. In the polymerization reactor to which the present invention can be applied, the shape of the polymerization reactor, the position and number of the blowing pipes, the stirring, The shape and position of the wing, the presence or absence of a circulation line, and the like are not limited thereto.

The polymerization solvent used for the solution polymerization includes, for example, aliphatic hydrocarbons such as hexane, heptane, octane and kerosene; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; benzene, toluene,
Aromatic hydrocarbons such as xylene are raised, and as the α-olefin, propylene, 1-butene, 1-pentene,
Α-olefins having 3 to 20 carbon atoms, such as 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene and 1-decene, are exemplified.

In the present invention, when ethylene is supplied to a polymerization reactor in a gaseous state and copolymerized with a comonomer in a liquid phase,
The gel formation is prevented by supplying ethylene into the polymerization solution under the condition that the gel formation parameter defined by the following formula is 1 × 10 ⁻⁴ or less, preferably 6 × 10 ⁻⁵ or less.

Gel formation parameter = M / PM where M is the amount of ethylene absorbed per unit volume of the polymerization liquid / the number of blowing tubes (unit: kg / s / m ³ / number) P is the dispersion near the gas supply port in the unit volume of the polymerization liquid Force (reciprocal of the time required to dilute the ethylene gas introduced into the polymerization solution by 100 times) (unit: 1 / s / m ³ ) In the above formula, the ethylene absorption amount per unit volume of the polymerization solution and Is the amount of ethylene absorbed into the liquid from the blown gas divided by the volume of the polymerization liquid. The ethylene absorption amount can be defined by (ethylene concentration in blown gas−gas phase ethylene concentration equilibrated with the polymerization solution) × blow flow rate.

The number of blowing pipes is the number of blowing pipes (blowing pipe 10 in the example shown in FIG. 1) for supplying ethylene gas into the polymerization vessel. P is a dispersing force at a gas supply port (gas outlet of a blowing pipe), and is a time required for diluting ethylene gas introduced into the polymerization solution by 100 times (hereinafter, referred to as “100 times dilution time”). Is the reciprocal of

Here, the 100-fold dilution time is usually carried out as follows. FIG. 2 is a conceptual diagram for explaining a method of measuring the 100-fold dilution time. The measurement of the 100-fold dilution time was performed using a tank-type stirring tank as described above, using iodine or the like as a tracer, taking a picture of the diffusion using a high-speed video camera, and until the tracer was diluted 100-fold. By measuring the time.

More specifically, a tracer is supplied from a blowing pipe into a polymerization solution in a polymerization vessel. The supplied tracer is gradually diffused and diluted as shown in, for example, (a-1) to (a-4) of FIG. At this time, the projected area (the area of the hatched circle in FIGS. 2 (b-2) to (b-4)) of the portion corresponding to the portion where the tracer supplied first was diluted was measured, and this projection was performed. the volume of a sphere having the same projected area as a V _n. Area of a circle of the inner diameter of the blow tube to the diameter of the volume of a sphere having a (circular area indicated by oblique lines in FIG. 2 (b-1)) equal to the projected area and V _1, 100-fold V _n is V ₁ Is defined as the 100-fold dilution time. This 100-fold dilution time is usually 0.000
Within the range of 1 to 1 second.

In order for the gel formation parameter to be 1 × 10 ⁻⁴ or less, the shape of the polymerization vessel of the polymerization vessel, the diameter of the blowing pipe and the position and orientation of the supply port, the amount of ethylene blown, and the amount of the stirring blade The shape and position, stirring power, and the like are appropriately set.

Although it is desirable to perform such a measurement in a practical size, it may be measured by a similarity tester. A model having an actual volume of about 0.05 to ⁵ m ³ is usually used for a model experiment. Further, instead of the polymerization liquid, a simulation liquid having the same viscosity may be used. At this time, the dispersion force due to the difference in scale is corrected in accordance with the power of the stirring blade.
Since the dispersing force is determined by the energy used for stirring, the dispersing force is measured using a similar-shaped tester together with the power per unit volume of the liquid, and the dispersing force is divided by the liquid volume in the model experiment to obtain the polymerization. It becomes equivalent to the dispersing force P per unit volume of liquid.

According to the present invention, the polymerization viscosity is 1 poise or more,
Further, at 10 poise or more, particularly at 50 poise or more, liquid phase polymerization of ethylene and an α-olefin can be performed without producing a high ethylene gel. Therefore, a high-quality ethylene / α-olefin copolymer can be produced with high productivity.

The process of the present invention comprises a titanium catalyst comprising a solid titanium catalyst component and organoaluminum, a vanadium catalyst comprising a soluble vanadium compound and an organoaluminum compound, and a metallocene of a transition metal selected from Group 4 of the periodic table. It can be used for solution polymerization of ethylene and α-olefin using a catalyst comprising a transition metal compound and an organometallic compound, such as a metallocene catalyst comprising a catalyst and an organic aluminum oxy compound and / or an ionized ionic compound. it can.

The ethylene content in the ethylene copolymer obtained by the method of the present invention is not particularly limited, but is generally 40 to 99 mol%, preferably 50 to 95 mol%, more preferably 60 to 92 mol%. is there.

This method can be used not only when designing polymerization equipment but also when controlling polymerization. The polymerization conditions are controlled so as to keep the gel formation parameter at 1 × 10 ⁻⁴ or less, based on the dispersion force of the supply port which is appropriately measured at the time of designing the polymerization equipment or, if necessary, using a model device. The correlation of the dispersing power at the gas supply port under each viscosity and each stirring rotation speed is grasped, and the polymerization conditions such as gas supply speed, ethylene concentration in the blowing gas, ethylene concentration equilibrium with the polymerization solution, and the number of blowing tubes The optimum conditions are calculated based on the correlation with the factors, the factors requiring the change and the magnitude of the deviation are obtained, and the control is performed based on the factors. The control factors that control the gel formation parameters include the ethylene supply amount, the pressure and temperature in the mechanism for separating gas and condensate, the number of ethylene blowing tubes, the flow rate of blowing gas, and the ethylene concentration equilibrium with the polymerization solution (polymerization temperature and ethylene concentration). (Partial pressure), stirring power, and solution viscosity, and one or more of them are controlled in combination. For example,
The lower the temperature in the mechanism for separating the gas and the condensate, the higher the ethylene concentration and the amount of condensate in the condensate, so that the ethylene concentration and the amount of the blown gas in the blown gas can be reduced. For these controls, a database may be created in advance and automatically controlled by the database.

The above gel formation parameter is set to 1 × 1
The method of controlling the polymerization conditions so as to keep the polymerization temperature at ^0-4 or less can be applied to the case where an ethylene-based copolymer is produced by using a polymerization facility as shown in FIG. Control factors for controlling the gel formation parameter when producing an ethylene copolymer include ethylene feed rate, heat exchanger temperature, gas-liquid separator pressure and temperature, ethylene blowing pipe number, blowing gas flow rate, There are ethylene concentration (polymerization temperature and ethylene partial pressure) equilibrium with the polymerization liquid, stirring power, solution viscosity, and the like. Among these, at least the temperature of the heat exchanger is controlled. Other control factors are appropriately set so that the gel formation parameter satisfies the above range.

The above gel formation parameter is set to 1 × 1
The polymerization equipment capable of polymerizing ethylene and α-olefin so as to keep it at ^0-4 or less includes the ethylene supply amount, the temperature of the heat exchanger, the pressure and temperature of the gas-liquid separator, the number of ethylene injection pipes, and the flow rate of blown gas Polymerization equipment designed so that control factors such as ethylene concentration (polymerization temperature and ethylene partial pressure) equilibrium with the polymerization solution, stirring power, and solution viscosity can be set so that the gel formation parameter falls within the above range.

The polymerization equipment capable of polymerizing ethylene and α-olefin so as to keep the gel formation parameter at 1 × 10 ⁻⁴ or less includes the following polymerization equipment as shown in FIG. Ethylene supply rate, heat exchanger temperature, gas-liquid separator pressure and temperature, number of ethylene blowing tubes, blowing gas flow rate, ethylene concentration equilibrium with polymer solution (polymerization temperature and ethylene partial pressure), stirring power, solution viscosity Polymerization equipment designed so that control factors such as the above can be set so that the gel formation parameter falls within the above-mentioned range.

As shown in FIG. 5, the polymerization equipment preferably used in the method for producing an ethylene copolymer according to the present invention is a mixture of ethylene and α-olefin in the presence of ethylene, α-olefin and a polymerization catalyst in a gas-liquid state. Polymerizer 1 for polymerizing olefin
A piping device 44 for extracting the gas phase of the polymerization reactor 41 to the outside of the polymerization reactor 41; a heat exchanger 45 for cooling the extracted gas phase (mixed gas) to remove polymerization heat; A separator (for example, a drum) 46 for separating a condensed liquid condensed by heat removal and a mixed gas (non-condensed gas) not condensed;
And a supply device for re-supplying the liquid to the air.

The polymerization vessel 41 is provided with ethylene A as a raw material.
It has a gas blowing nozzle 42 for supplying a non-condensable gas containing (gas) into the tank, and a stirrer 43 for stirring the liquid phase in the tank. The supply end of the gas injection nozzle 42 is provided in a liquid phase near the bottom in the polymerization vessel 41.

The polymerization vessel 41 has a supply port 54 at the bottom, a supply port 54 at the lower part of the side wall, a discharge port 55 at the middle part of the side wall, and a discharge port 56 at the upper part. The supply port 51 is connected to a supply pipe 51a for supplying a catalyst (for example, a metallocene catalyst) C. In addition, the supply port 54
Is connected to a supply pipe 54a for supplying a solvent (for example, a hexane solvent) D. Further, the discharge port 55 is connected to a discharge pipe 55a for discharging a solution-state polymerization liquid (ethylene / α-olefin copolymer) E. Furthermore, the outlet 5
6 is connected to the piping of the piping device 44 for discharging the mixed gas.

The stirrer 43 has a motor 43a and a stirring blade (impeller) 43b connected to a rotating shaft of the motor 43a. Further, the piping device 44 has a piping connected from the outlet 56 of the polymerization vessel 41 to the drum 46 via the heat exchanger 45. A portion connected to the discharge port 56 in the pipe is an extraction pipe.

A supply port 50 and a supply port 52 are provided in a pipe connected from the discharge port 56 to the drum 46 via the heat exchanger 45. The supply port 50 is connected to a supply pipe 50a for supplying the raw material ethylene A. Then, at least a part of the ethylene A newly supplied to the polymerization reactor 41 is supplied from the supply port 50 via the supply pipe 50a. The supply amount of ethylene A supplied from the supply port 50 is desirably 50% or more of the total supply amount of ethylene A newly supplied to the polymerization reactor 41.

The supply port 52 is connected to a supply pipe 52a for supplying propylene B (liquid) as a raw material.
The heat exchanger 45 is a device for removing the heat of polymerization from the passing gas. The heat exchanger 45 may be any type as long as it can remove a necessary amount of heat and can withstand long-term use. However, description will be made using a multi-tube heat exchanger.

The heat exchanger 45 has a tank 45a through which a coolant (for example, cooling water) CCW is passed, and a number of small tubes 45b passing through the tank 45a. The thin tube 45b of the heat exchanger 45 is connected to the piping of the piping device 44.

The drum 46 comprises a tank for temporarily storing the raw material and the mixed gas. This tank contains a filter 46a.
May be provided. The filter 46a has a fiber layer for removing impurities from the raw material and the mixed gas passing therethrough.

The drum 46 is provided with a supply port 4 on the side wall of the tank.
6b, a discharge port 46c at the bottom, and a discharge port 46d at the top. The supply port 46b is located lower than the liquid level of the drum 46. Also,
The supply port 46b is connected to the piping of the piping device 44.

The outlet 46c is connected to a supply pipe 49b of a supply device for transferring the condensate. Further, the outlet 46d is connected to a supply pipe 49a of a supply device for transferring non-condensable gas.

The supply device includes a supply pipe 49a connected from the discharge port 46d of the drum 46 to the gas injection nozzle 42 via the blower 47, and a polymerization unit 41 via the pump 48 from the discharge port 46c of the drum 46. And a supply pipe 49b connected to the supply port 51. The supply pipe 49b is
It is also connected to the supply pipe 51a of the metallocene catalyst C.

The blower 47 is a machine that applies pressure to a gas (non-condensed gas) with a fan and sends it out. The intake side and the exhaust side of the blower 47 are connected to a supply pipe 49a.

The pump 48 is a machine for rapidly sending a liquid (condensed liquid) to the spiral chamber at the outer periphery by an impeller, and is, for example, a centrifugal pump. The suction side and the discharge side of the pump 48 are connected to a supply pipe 49b.

Next, a polymerization method using such a polymerization facility will be described. In this polymerization facility, the raw materials used were ethylene A and propylene B, and the metallocene catalyst C was used.
And the case where hexane solvent D is supplied to carry out uniform polymerization in the liquid phase of the polymerization vessel 41.

First, the raw material ethylene A is supplied from the supply pipe 50a to the supply port 50 of the piping device 44, and the raw material propylene B is pumped by the pump 53 and supplied from the supply pipe 52a to the supply port 52 of the piping device 44. .

Then, ethylene A and propylene B are transferred from the supply port 46b into the drum 46, and are temporarily stored while being partially dissolved by the drum 46. And ethylene A
And propylene B are separated in a drum 46 into a liquid phase (propylene B and a polymerization liquid) and a gas phase (ethylene A).

The non-condensable gas mainly composed of ethylene A is
Due to the negative pressure of the blower 47, the supply pipe 49a is discharged from the discharge port 46d.
Discharged through the supply pipe 49a.
And supplied from the gas injection nozzle 42 to the polymerization reactor 41.

The condensate containing propylene B as a main component is discharged from a discharge port 46c to a supply pipe 49b. Supply pipe 49
The condensate in b is pumped to the pump 48 and supplied from the supply port 51 to the liquid phase of the polymerization reactor 41. In addition, the metallocene catalyst C and the hexane solvent D are supplied to the respective supply pipes 51a, 54
The liquid is continuously supplied from the supply ports 51 and 54 to the polymerization reactor 41 via the line a. Here, the hexane solvent D may include unreacted ethylene A or propylene B extracted from the polymerization vessel 41.

Then, the stirrer 43 stirs the non-condensable gas and the condensate together with the metallocene catalyst C and the hexane solvent D by the stirring blade 43b. The metallocene catalyst C promotes polymerization, and the hexane solvent D promotes solution. As a result, ethylene A and propylene B are polymerized, and the ethylene / α-olefin copolymer E
Is generated.

On the other hand, a gas (vapor phase) that evaporates without being in a solution state due to the heat generated by polymerization is generated in the upper portion of the polymerization vessel 41. This vapor phase is a mixed gas containing ethylene A, vaporized propylene B, and vaporized hexane solvent D.

Then, the vapor phase (mixed gas) is discharged from the discharge port 56 to the piping of the piping device 44. The discharged mixed gas is transferred to the heat exchanger 45 through the piping of the piping device 44, and passes through the narrow tube 45b of the heat exchanger 45. Then, the heat exchanger 45 removes polymerization reaction heat from the mixed gas passing through the narrow tube 45b by a heat exchange action with the refrigerant CCW. Thereby, the mixed gas is partially condensed and becomes a gas-liquid mixture of the condensed liquid and the non-condensed gas.

The cooled mixed gas (gas-liquid mixture) is mixed with ethylene A supplied from the supply port 50 and propylene B supplied from the supply port 52, and is temporarily stored in the drum 46 from the supply port 46b. (Mixing step). This mixing step is performed until the mixed gas is separated into a condensed liquid condensed by cooling and a gas not condensed. Then, the ethylene A supplied from the supply port 50 is mixed with the cooled mixed gas, cooled, and partially dissolved (polymerized) in the condensed liquid by the drum 46.

Therefore, in the drum 46, while the mixed gas is temporarily stored, the condensed liquid (liquid mainly composed of propylene B) condensed by cooling and the non-condensed gas (mainly ethylene A Containing mixed gas).

The non-condensable gas is discharged from the outlet 46d to the supply pipe 49a by the negative pressure of the blower 47. Then, the non-condensable gas in the supply pipe 49a is sent to the blower 47 under pressure and supplied from the gas blowing nozzle 42 to the polymerization reactor 41. In addition, 50% or more of the total supply amount of ethylene newly supplied to the polymerization reactor 41 is mixed with the cooled mixed gas,
After being partially dissolved in the condensed liquid by the drum 46, the condensed liquid is supplied to the polymerization unit 41 from the gas injection nozzle 42.

On the other hand, the condensate containing propylene B as a main component is discharged from a discharge port 46c to a supply pipe 49b. The condensate in the supply pipe 49b is sent to the pump 48 by pressure and supplied to the supply port 5b.
1 to the liquid phase of the polymerization vessel 41.

Accordingly, the polymerization vessel 4 is
The non-condensable gas supplied to 1 is a mixture of the raw material ethylene A and the mixed gas, and has a lower ethylene concentration than the raw material ethylene A.

Therefore, when ethylene having a relatively low concentration (that is, a mixed gas) is brought into contact with propylene B and stirred, a region having a high ethylene concentration in the polymerization solution can be reduced, and the cause of high ethylene gel can be eliminated. A uniform polymerization reaction can be obtained in the polymerization vessel.

In the above embodiment, the raw material ethylene A
Is connected to the piping device 44, and the raw material ethylene A is mixed with the mixed gas in the piping of the piping device 44 and supplied. As another embodiment, the supply port of the raw material ethylene A is The raw material ethylene A may be provided below the liquid level of 46 and mixed with the condensed liquid in the drum 46 and supplied.

According to the polymerization equipment as described above, the raw material ethylene is mixed with the mixed gas and cooled by the heat exchange action of the heat exchanger, and then brought into contact with the condensate, or the raw material ethylene is mixed with the condensate. And partially dissolving with the condensate, the mixed gas having a lower ethylene concentration than the raw material ethylene can be brought into contact with the α-olefin composition and stirred. Therefore, in the polymerization reactor, the ethylene concentration is kept low as compared with the raw material ethylene, and the non-uniformity of the polymerization reaction in the polymerization reactor is reduced,
The formation of high ethylene gel can be prevented.

[0070]

According to the process for producing an ethylene / α-olefin copolymer of the present invention, copolymerization of ethylene and α-olefin is carried out in a liquid phase with a high solution viscosity while suppressing the production of high ethylene gel. be able to.

[0071]

EXAMPLES Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to these examples.

Measurement of 100-fold dilution time Prior to the continuous polymerization test, the dispersion force near the gas supply port was measured by a model experiment. Fig. 3
It is as follows. In FIG. 3, 31 is a polymerization vessel, 32 is a baffle, 33 is a liquid, 34 is a blowing tube, 35 is a stirrer, and 37 is a high-speed video camera.

A stirring tank made of transparent vinyl chloride and having exactly the same shape as the continuous polymerization equipment described later was used. That is, the shape of the polymerization vessel, the shape and position of the stirring blade, the number of blow tubes, the tube diameter and position, the shape and position of the baffle are all the same, the liquid level is adjusted to the continuous polymerization equipment, and the viscosity and stirring are performed. Dispersion force was measured by changing the power at several points.

In the test, a transparent vinyl chloride cylinder having an inner diameter of 550 mm was used as a side of the stirring tank, and a semi-elliptic sphere also made of transparent vinyl chloride was used as a tank bottom. As baffles, four vinyl chloride plates having a width of 44 mm were installed so as to be even in the circumferential direction. As a stirring blade, diameter 38
Two paddle blades having a width of 5 mm and a width of 38.5 mm were used in two stages. The lower agitator is installed at the height of the connection between the semi-elliptical sphere and the cylinder, and the upper aerofoil is installed at a height between the gas-liquid interface and the lower wing, so that the center of the cylinder coincides with the center of the wing. did.
The inlet is horizontal with the lower stirring blade, and the stirring blade is 15m
It was installed so as to be blown toward the center of the wing at a distance of m. The diameter of the blowing port was 24 mm. Two inlets were provided for gas injection and one for tracer supply. The two gas inlets were installed at a circumferential position of 180 °, and the tracer supply port was installed at a circumferential position of 90 ° with respect to the gas inlet.

In the simulation test, water was used as a liquid, and sodium carboxymethyl cellulose was used as a viscosity modifier. The viscosity was adjusted by the concentration of sodium carboxymethylcellulose, and the test was performed in a viscosity range of 0.01 to 100 poise. For the measurement of the dispersing power, a solution obtained by dissolving iodine in ethanol at a concentration of 20 g / liter as ethanol was used as a tracer, and the solution was introduced from a blowing port. At that time, the blowing speed of the tracer was set to 4.6 m / s in accordance with a test by a continuous polymerization apparatus described later. In addition, in order to adjust the ventilation conditions, air was blown at 4.6 m / s from two gas inlets.
(Total blowing rate of 15 m ³ / hr). The spread of the tracer was photographed with a high-speed video camera, and the 100-fold dilution time was measured.

[0076]

Example 1 Ethylene / 1-butene copolymer A test was carried out using a continuous polymerization apparatus shown in FIG. Solvent dehydrated and purified from the supply tube 11 to the continuous polymerization reactor 1 having a volume of 300 liters (n-hexane 60% by volume, methylcyclopentane 22% by volume, 3-methylpentane 18% by volume)
At a rate of 38.7 l / hr, a hexane solution of triisobutylaluminum (2.5 mmol / l) at a rate of 4 l / hr, a hexane slurry of methylaluminoxane (3.4 as an aluminum atom).
Milligram atom / liter) at a rate of 6.4 liter / hr and bis (1,3-dimethylcyclopentadienyl) zirconium dichloride in hexane (0.12 mmol / liter) at a rate of 0.9 liter / hr. (Total hexane 50 l / hr).

At the same time, 7.5 k of ethylene was supplied from the supply pipe 16.
g / hr at a rate of 1.2 normal liters / h of hydrogen
r, and 1-butene is supplied from the supply pipe 17 at 17 kg.
/ Hr continuously at a polymerization temperature of 90 ° C. and a total pressure of 12
The copolymerization was performed under the conditions of kg / cm ² -G and a residence time of 1.5 hours. The solution of the ethylene / 1-butene copolymer produced in the polymerization vessel 1 is continuously discharged through a discharge pipe 15, the pressure is increased to 50 kg / cm ² -G by a pump 18, and the temperature is increased by a heat exchanger 19. After the temperature was raised to 200 ° C., the mixture was guided into the hopper 20, and the solvent and unreacted monomers were separated by evaporation to obtain a copolymer at a rate of 7.2 kg / hr.

In order to remove the heat of polymerization, a gas circulation system and a jacket cooling system were used. The ethylene gas, the vaporized α-olefin and the solvent in the gas phase of the polymerization reactor were discharged from the circulation line 12 and mixed with the ethylene gas and hydrogen gas supplied from the supply pipe 16 in a line. Thereafter, the mixed gas was introduced into the heat exchanger 2, and ethylene gas and liquefied α-olefin were introduced into the gas-liquid separator 3. The liquid phase (mainly α-olefin and solvent) separated by the gas-liquid separator 3 was supplied again from the supply pipe 13 to the polymerization reactor. The gas phase was supplied again to the polymerization reactor 1 through the blower 4 and the supply pipe 14 at a rate of 15 m ³ / hr. In order to measure the amount of ethylene absorbed at the gas inlet, the gas composition of the blown gas and the gas phase of the polymerization reactor were measured, and the gas composition of the gas phase of the polymerization reactor was regarded as a gas composition equilibrium with the polymerization liquid. The shape of the polymerization vessel such as the shape of the tank, the stirring blade, the baffle, and the blowing tube was the same as that of the vinyl chloride tank shown in Example 1. The stirring power was measured by installing a torque meter on a stirring shaft, and controlled by the rotation speed of the stirring, and a test was performed in the range of 2 to ⁵ kW / m ³ .

The intrinsic viscosity [η] of the ethylene / 1-butene copolymer obtained in the tested stirring power range in decalin at 135 ° C. was 1.5 to 1.6 dl / g and ¹³ C.
The ethylene content as determined by NMR is 89-90 mol%
Met.

[0080]

Example 2 Copolymerization of ethylene / 1-butene A test was carried out using the same continuous polymerization apparatus as in Example 1.
That is, a solvent dehydrated and purified from the supply pipe 11 into the continuous polymerization reactor 1 (n-hexane 60% by volume, methylcyclopentane 2
Hexane solution of triisobutylaluminum (2.5 mmol / l) at a rate of 4 liters / hr and hexane of methylaluminoxane at a rate of 42.7 liters / hr. A slurry (3.4 milligram atoms / liter as aluminum atoms) of a hexane solution (0.12 mmol / liter) of bis (1,3-dimethylcyclopentadienyl) zirconium dichloride was added at a rate of 2.9 liters / hr. It was continuously fed at a rate of 0.4 l / hr (total hexane 50 l / hr).

Simultaneously, ethylene was supplied to the polymerization reactor 1 from the supply pipe 16 at a rate of 4.2 kg / hr and hydrogen was supplied at a rate of 0.8 N-liter / hr.
at a polymerization temperature of 90 ° C., a total pressure of 12 kg / cm ² -G, and a residence time of 1.5 hours. The copolymer was fed at a rate of 4.6 kg / hr. Obtained. The test was performed under the same conditions as in Example 1 except for the above.

The intrinsic viscosity [η] of the ethylene / 1-butene copolymer measured in decalin at 135 ° C. was 1.5 to 1.6 dl / g and ¹³ C-
The ethylene content measured by NMR was 89-90 mol%.

The ethylene / 1- obtained in Examples 1 and 2
Each of the butene copolymers was extruded at 200 ° C. using a 30 mm T-die and quenched with a chill roll at 27 ° C. to form a 50 μm film. FIG. 4 shows the correlation between the number of high ethylene gels in the prepared film and the gel formation parameters. Gel generation can be suppressed by reducing the gel generation parameter.

[0084]

Example 3 A test was conducted using the polymerization equipment shown in FIG. The unreacted monomer recovered in the post-treatment step was fed from the pipe 54a to the continuous polymerization reactor 41 having a volume of 80 m and having a similar shape to that of Example 1;
Distilled and purified solvent (methylcyclopentane 60% by volume,
3-methylpentane (40% by volume).
It was supplied at a rate of 20 m ³ / hr. From a tube 51a, a hexane solution of triisobutylaluminum (2.5 mmol / l) at a rate of 1.8 m ³ / hr and a hexane slurry of methylaluminoxane (3.4 mg atoms / l as aluminum atoms) of 1.3 m ³ were added. / H
r, bis (1,3-dimethylcyclopentadienyl) zirconium dichloride in hexane solution (0.12
(Mmol / l) was continuously supplied at a rate of 0.2 m ³ / hr. 3330kg / ethylene from pipe 10a
At a rate of hr, hydrogen is supplied at a rate of 400 N-liter / hr, and propylene is supplied from a pipe 52a at 1170 kg / hr.
At a rate of 2. Using four gas injection pipes 42,
The copolymerization was carried out under the conditions of a stirring power of 3.0 kW / m ³ , a polymerization temperature of 90 ° C., a total pressure of 12 kg / cm ² -G and a residence time of 1.5 hours. The solution of the ethylene / propylene copolymer produced in the polymerization vessel 41 was continuously discharged through a pipe 55a, and the solvent and unreacted monomers were separated by evaporation to obtain a copolymer at a rate of 4500 kg / hr. . The solvent separated by evaporation and the unreacted monomer were separated by evaporation, and 3.3 m ³ / hr was branched off from the whole solvent and used in a catalyst supply system. The remaining solvent and unreacted monomer are mixed, and the tube 54 as described above is mixed.
a to the polymerization vessel 41.

The intrinsic viscosity [η] of the obtained ethylene / propylene copolymer measured in decalin at 135 ° C. was 1.
The ethylene content measured by 45 dl / g and ¹³ C-NMR was 80 to 82 mol%. The gel formation parameter in this example was 5.9 × 10 ⁻⁵ , and the number of gels was about 13 / m ² , which was a level at which no ethylene gel was generated in practical use.

[0086]

Example 4 A test was conducted using the polymerization equipment shown in FIG. Content
Tube 1 in a continuous polymerization reactor 1 having a volume of 80 m and similar in shape to Example 1
4a, the unreacted monomer recovered in the post-treatment
Distilled and purified solvent (methylcyclopentane 60% by volume, 3-
Methylpentane (40% by volume), and
0m^Three/ Hr. Triiso from tube 51a
Butyl aluminum in hexane (2.5 mmol /
1.8m ^Three/ Hr, methyl aluminum
Noxane hexane slurry (as aluminum atom)
(3.4 milligram atoms / liter) to 1.3 m^Three/ Hr
Bis (1,3-dimethylcyclopentadienyl)
Hexane solution of zirconium dichloride (0.12 mm
Mol / l) 0.2m^Three/ Hr continuously
Supplied. 3330 kg / hr of ethylene from pipe 50a
At a rate of 400 N-liter / hr
And propylene from the pipe 52a at a rate of 1170 kg / hr.
In this case, they were continuously supplied. Stirring using four gas injection pipes 42
Power 3.0 kW / m^Three, Polymerization temperature 90 ° C, total pressure 1
2kg / cm^Two-G, copolymerization with a residence time of 1.5 hours
Was done. Ethylene / propylene produced in polymerization unit 41
The copolymer solution is continuously drained and the solvent and unreacted
The monomer is separated by evaporation, and the copolymer is 4500 kg
/ Hr. Unreacted products with solvent separated by evaporation
The mer was evaporated off and 3.3 m from the total solvent^Three/ Hr branch
And used for the catalyst supply system. Remaining solvent and unreacted monomer
And supplied to the polymerization reactor 41 from the tube 54a as described above.
did.

The intrinsic viscosity [η] of the obtained ethylene / propylene copolymer measured in decalin at 135 ° C. was 1.
The ethylene content measured by 42 dl / g and ¹³ C-NMR was 80 to 82 mol%. The gel formation parameter in this example was 7.3 × 10 ⁻⁵ , and the number of gels was about 30 / m ² .

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of a tank type polymerization vessel to which the present invention can be applied.

FIG. 2 is a conceptual diagram for explaining a method for measuring a dilution time of ethylene.

FIG. 3 is a schematic view of an apparatus used for measuring a dispersion force near a gas supply port.

FIG. 4 is a diagram showing a correlation between the number of high ethylene gels in a film produced in an example and a gel formation parameter.

FIG. 5 is an equipment layout diagram showing an example of a polymerization facility to which the present invention can be applied.

FIG. 6 is an equipment layout diagram of a conventional polymerization facility.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Polymerizer 2 ... Heat exchanger 3 ... Gas-liquid separator 4 ... Blower 5 ... Stirrer

Claims (4)

[Claims] (1) When ethylene is supplied to a polymerization vessel in a gaseous state and copolymerized with a comonomer in a liquid phase, ethylene is supplied under a condition that a gel formation parameter defined by the following formula is 1 × 10 ⁻⁴ or less. A method for producing an ethylene copolymer, characterized in that the polymer is supplied into a polymerization liquid; gel formation parameter = M / PM: ethylene absorption per unit volume of polymerization liquid / number of blowing pipes (unit: kg / s / m) ³ / number) P: Dispersion force in the vicinity of gas supply port in unit volume of polymerization liquid (reciprocal of time required to dilute ethylene gas introduced into polymerization liquid by 100 times) (unit: 1 / s) / m ³⁾ 2. The process for producing an ethylene copolymer according to claim 1, wherein the viscosity of the solution in the solution polymerization is 1 poise or more. 3. The method for producing an ethylene copolymer according to claim 1, wherein an ethylene copolymer having an ethylene content of 40 to 99 mol% is produced. 4. When ethylene is supplied to a polymerization vessel in a gaseous state and copolymerized with a comonomer in a liquid phase, a gel formation parameter defined by the following equation is set to a value satisfying 1 × 10 ^-4 or less. Gel production parameter = M / PM: ethylene absorption per unit volume of polymerization liquid / number of blowing pipes (unit: kg / s / m ³⁾ P: Dispersion force near the gas supply port in the unit volume of the polymerization liquid (reciprocal of the time required to dilute the ethylene gas introduced into the polymerization liquid by 100 times) (unit: 1 / s / m ³⁾