JP2015120776A - Method and apparatus for manufacturing powder polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for stably manufacturing a powder polymer having an even particle diameter and shape, by controlling a resident time of content in a polymerization reactor in powder bed continuous mass polymerization.SOLUTION: A method for manufacturing a powder polymer includes: continuously supplying under agitation a raw material monomer and a polymerization catalyst for generating the powder polymer to a polymerization reactor where the powder polymer exists; and continuously extracting the powder polymer from a powder polymer extracting port of the polymerization reactor. Furthermore, the method for manufacturing the powder polymer includes performing resident time control for controlling a discharge on-off valve provided on a discharge path of the powder polymer extracting port so as to bring an observation resident time of the content in the polymerization reactor to a target resident time of the content in the polymerization reactor.

Description

  The present invention relates to a method for producing a powder polymer by a continuous bulk polymerization reaction.

  Powder bed continuous bulk polymerization is known as one of methods for producing a styrene polymer, a propylene polymer, and the like (see, for example, Patent Documents 1 and 2). According to this method, the raw material monomer absorbed in the seed polymer present in the polymerization reactor is obtained by continuously supplying the raw material monomer and the catalyst with stirring to the polymerization reactor in which the powder polymer is present as the seed polymer. Is polymerized, and a powder polymer can be obtained without using a solvent. Since no solvent is used, a step of recovering the solvent after the reaction becomes unnecessary, and the cost can be reduced. Further, since the product is mainly composed of a polymer and unreacted monomers, a high-purity polymer can be obtained simply by recovering the monomer by decompression or drying.

By the way, generally, in order to obtain a polymer having desired physical properties uniformly, it is important to control the polymerization reaction according to the reaction rate and the reaction time. Since the reaction rate can be constant when the raw material charge, reaction temperature, catalyst concentration, etc. are constant, in powder bed continuous bulk polymerization, the residence time of the contents in the polymerization reactor related to the reaction time Can control the particle size, shape, molecular weight distribution, and in the case of a copolymer, polymer particles having a uniform composition distribution can be obtained. If the residence time is too short, the polymer particles are discharged before they are sufficiently grown.On the other hand, if the residence time is too long, the polymer particles are bonded together to form coarse particles or dumbbell-shaped irregularly shaped particles. Sometimes it forms.
However, in the powder system, unlike the liquid system, it is difficult to measure the total mass of the polymer particles inside the polymerization reactor, so it is difficult to control the residence time of the contents in the polymerization reactor in real time. It is.

  Therefore, conventionally, in the powder system as well as in the liquid system, the rate at which the produced polymer is extracted from the polymerization reactor is controlled, and the volume of the contents in the polymerization reactor is controlled to be constant. The actual situation is regarded as control of the residence time of the contents (see Patent Documents 1 and 2). For example, Patent Document 1 discloses that a flow pattern of a fluid is converted into a plug flow by using a horizontal reactor, and the residence time distribution is narrowed to the same extent as a plurality of reactors arranged in series. According to the description of the examples, it is disclosed that the produced polymer is intermittently withdrawn from the polymerization reactor so that the volume of the reaction system in the polymerization reactor becomes constant. To keep the volume of the reaction system in the polymerization reactor constant, the upper surface position (gas-solid interface) of the contents in the polymerization reactor is observed, and the production polymer is extracted so as to keep the position constant. Is generally controlled.

JP 2011-116970 A JP-A-5-093015

  However, in the conventional method, the residence time of the contents in the polymerization reactor cannot be controlled, and the residence time varies due to small fluctuations in the operation of the apparatus, leading to instability of the polymer particle shape, A fluctuation in power or torque that rotates the stirring blade in the polymerization reactor occurs, which hinders stable operation. Therefore, improvement is required so that the residence time of the contents in the polymerization reactor can be sufficiently controlled.

  Therefore, the problem to be solved by the present invention is to stably produce a powder polymer having a uniform particle size and shape by controlling the residence time of the contents in the polymerization reactor in the powder bed continuous bulk polymerization. It is to provide a way to do.

As a result of pursuing the reason why the residence time of the contents in the polymerization reactor cannot be controlled by the conventional method, the present inventor has determined that the top surface position of the contents in the polymerization reactor is controlled to be constant. When the particle size distribution of the particles fluctuates and the bulk density of the contents changes, the mass of the contents in the polymerization reactor fluctuates, so that the residence time of the contents in the polymerization reactor is substantially reduced. I found out that I was not able to control.
As a result of further earnest studies, the present inventor found that the fluctuation of the power or torque for rotating the stirring blade in the polymerization reactor correlates with the fluctuation of the bulk density of the contents in the polymerization reactor. It was found that the true residence time of the contents in the polymerization reactor can be controlled based on this correlation.
The present invention has been completed based on these findings.

That is, this invention relates to the following powder polymer manufacturing methods and manufacturing apparatuses.
<1> A raw material monomer for generating a powder polymer and a polymerization catalyst are continuously supplied to a polymerization reactor in which the powder polymer is present under stirring, and the powder is continuously discharged from the powder polymer outlet of the polymerization reactor. A powder polymer manufacturing method for extracting a body polymer,
Residence for controlling the discharge on-off valve provided in the discharge passage of the powder polymer outlet so that the observed residence time of the contents in the polymerization reactor becomes the target residence time of the contents in the polymerization reactor Powder polymer manufacturing method for time control.
<2> The method for producing a powder polymer according to <1>, wherein the observation residence time of the contents in the polymerization reactor is calculated by the following formulas (1) and (2).
(Observation residence time of contents in polymerization reactor) = (mass of contents in polymerization reactor) / (feed mass of raw material monomer per unit time) (1)
(Mass of contents in polymerization reactor) = (Volume of contents in polymerization reactor) × (Bulk density of contents in polymerization reactor) (2)
<3> The bulk density of the contents in the polymerization reactor is calculated based on at least the torque or power required for stirring in the polymerization reactor correlated with the bulk density, <2> The powder polymer manufacturing method as described in any one of.
<4> The method for producing a powder polymer according to any one of <1> to <3>, wherein the supply mass of the raw material monomer per unit time is constant.
<5> When the observation upper surface position of the contents in the polymerization reactor deviates from the preset first management range, the observation upper surface position is changed in the polymerization reactor instead of the residence time control. The method for producing a powder polymer according to any one of <1> to <4>, wherein upper surface position control for controlling the discharge on-off valve is performed so as to be a target upper surface position of the contents.
<6> When the upper surface position control is performed and the observed upper surface position returns to the second management range set to be narrower than the first management range, the upper surface position control is performed. The method for producing a powder polymer according to the above <5>, wherein the method returns to the residence time control.
<7> Any one of the above items <1> to <6>, wherein the discharge on-off valve is controlled such that a standard deviation of a change rate of a difference between the observed residence time and the target residence time is 20% or less. The powder polymer manufacturing method as described.
<8> The method for producing a powder polymer according to any one of <1> to <7>, wherein the raw material monomer is styrene or propylene.
<9> A powder polymer production apparatus for producing a powder polymer by the powder polymer production method according to any one of <1> to <8>.

  According to the present invention, in powder bed continuous bulk polymerization, the true residence time of the contents in the polymerization reactor can be controlled, and a powder polymer having a uniform particle size and shape can be stably produced. Can do.

FIG. 1 is a process diagram showing an outline of a preferred embodiment of the method for producing a powder polymer of the present invention. FIG. 2 is a schematic diagram for explaining switching between residence time control and top surface position control by the automatic control device. FIG. 3 is a graph showing the change rate of the bulk density of the powder polymer in Examples and Comparative Examples.

  The method for producing a powder polymer of the present invention is applied to powder bed continuous bulk polymerization. Specifically, a raw material monomer for generating a powder polymer and a polymerization catalyst are continuously supplied to a polymerization reactor in which the powder polymer is present under stirring, and continuously from the powder polymer outlet of the polymerization reactor. In this method, the powder polymer is extracted.

  In the present invention, the “powder polymer” refers to a granular polymer having a particle size of 5000 μm or less. The particle size of the powder polymer produced by the method of the present invention is preferably 3500 μm or less, more preferably 2000 μm or less, and even more preferably 1500 μm or less. The lower limit of the particle size is not particularly limited, but is preferably 1 μm or more. The volume median particle size of the powder polymer is preferably 100 to 900 μm.

The type of the polymer produced by the method of the present invention is not particularly limited as long as it can be produced by powder bed continuous bulk polymerization. Specific examples of the types of polymers produced by the method of the present invention include olefin polymers such as propylene polymers (including cycloolefin polymers such as polynorbornene), rubber resins such as polybutadiene, and styrene resins. Examples include polymers, (meth) acrylic polymers, polyvinyl chloride, and the like. These may be homopolymers or copolymers. In the case of a copolymer, it may be a random copolymer or a block copolymer.
Among these, olefin polymers and styrene polymers are preferable, and propylene polymers and styrene homopolymers selected from propylene homopolymers and propylene-ethylene copolymers, styrene-ethylene copolymers, styrene-propylenes. Styrenic polymers selected from copolymers are more preferred. Further, among the styrenic polymers, syndiotactic polystyrene (SPS) is preferable.

The raw material monomer used in the present invention is a raw material for the above-mentioned polymer, and is appropriately determined according to the type of the target polymer. For example, when the target polymer is a propylene homopolymer or a styrene homopolymer, the raw material monomer is propylene or styrene, respectively. Although the state of the raw material monomer is not particularly limited, it is actually a liquid or a gas. For example, styrene, which is a raw material monomer for obtaining a styrene polymer, is a liquid.
Similarly, the polymerization catalyst used in the present invention is also appropriately determined according to the type of the target polymer. Specific examples include those disclosed in Japanese Patent Application Laid-Open No. 2011-116970 and Japanese Patent Application Laid-Open No. 5-093015.

  In the powder bed continuous bulk polymerization, the raw material monomer absorbed in the powder polymer as a seed polymer existing in the polymerization reactor is polymerized to grow the powder polymer. A part of the grown polymer collapses into fine particles, which further absorb the raw material monomer as a seed polymer and grow. The powder polymer that has grown to some extent is discharged sequentially from the polymerization reactor. By repeating this cycle, a powder polymer is continuously produced.

  The powder initially charged in the polymerization reactor in the powder bed continuous bulk polymerization may be the same powder polymer as the polymer produced from the raw material monomer, or a different powder. For example, resins such as polyethylene terephthalate, polypropylene, polyethylene, polycarbonate, polyethylene naphthalate, polyarylate, and nylon; inorganic materials such as silica, iron, stainless steel, copper, aluminum, nickel, chromium, gold, and silver; be able to. However, from the viewpoint of the uniformity of the quality of the polymer produced in the continuous polymerization, it is preferable to first charge the polymerization reactor with the same type of powder polymer as the polymer produced by the polymerization reaction of the raw material monomers.

  In the powder polymer production method of the present invention, the observed residence time of the contents in the polymerization reactor (referred to as “observation residence time of the contents in the polymerization reactor” in the present invention) is the contents in the polymerization reactor. The residence time control (control of the discharge on-off valve based on the residence time) is performed so as to control the discharge on-off valve provided in the discharge path of the powder polymer extraction port so that the target residence time is reached. Here, in the present invention, the mass density of the content in the polymerization reactor is controlled by regarding the fluctuation in the bulk density of the content as at least the power or torque fluctuation that rotates the stirring blade in the polymerization reactor. It is preferable to control the observation residence time of the contents in the polymerization reactor.

In the present invention, the observed residence time of the contents in the polymerization reactor can be calculated by the following equation (1).
(Observation residence time of contents in polymerization reactor) = (mass of contents in polymerization reactor) / (feed mass of raw material monomer per unit time) (1)
That is, the observed residence time of the contents in the polymerization reactor can be calculated by dividing the mass of the contents in the polymerization reactor by the supply mass of the raw material monomer per unit time. Here, the supply mass of the raw material monomer per unit time can be appropriately set from the density of the raw material monomer and the supply flow rate, and can be controlled in real time by any means.

The mass of the contents in the polymerization reactor can be calculated by the following equation (2).
(Mass of contents in polymerization reactor) = (Volume of contents in polymerization reactor) × (Bulk density of contents in polymerization reactor) (2)
That is, the mass of the content in the polymerization reactor can be calculated by the product of the volume of the content in the polymerization reactor and the bulk density of the content. The volume of the content in the polymerization reactor is calculated based on the size of the polymerization reactor by observing the upper surface position (gas-solid interface) of the content in the polymerization reactor.
The bulk density of the contents in the polymerization reactor is preferably calculated based on at least the torque or power required for stirring in the polymerization reactor correlated with the bulk density. That is, it is preferable to prepare in advance a calibration curve showing the correlation between the bulk density of the powder polymer and at least the power or torque for rotating the stirring blade in the polymerization reactor, and the powder discharged from the polymerization reactor Even when discrete data of bulk density is collected by sampling the polymer intermittently, it is converted into continuous data by correlating with the torque or power required for stirring in the polymerization reactor by comparing with the calibration curve. Based on this, it is possible to monitor the bulk density of the contents in the polymerization reactor in real time.
In addition, the fluctuation | variation of the motive power or torque which rotates the stirring blade in a polymerization reactor can be observed by arbitrary means.

  In the present invention, the discharge polymer discharge is controlled by controlling the discharge on-off valve provided in the discharge passage of the powder polymer outlet so that the observation residence time calculated above becomes a preset target residence time. The amount is adjusted. The discharge on / off valve is controlled so that the standard deviation of the change rate of the difference between the observed residence time and the target residence time is preferably 20% or less, more preferably 15% or less, and even more preferably 10% or less.

  From the viewpoint of facilitating control by reducing variables, that is, considering actual production, it is preferable to keep the supply mass of the raw material monomer per unit time constant. As is clear from the equation (1), the control equation can be simplified by controlling the supply mass of the raw material monomer per unit time to a constant value, and the residence time control is performed by the contents in the polymerization reactor. Can be replaced by mass control. In this case, the standard deviation of the rate of change in the difference between the observed mass of the contents in the polymerization reactor and the target mass is preferably 20% or less, more preferably 15% or less, and even more preferably 10% or less. Thus, the discharge on-off valve is controlled.

As described above, the volume of the content in the polymerization reactor is calculated based on the size of the polymerization reactor by observing the upper surface position (gas-solid interface) of the content in the polymerization reactor. At this time, the observed upper surface position of the content in the polymerization reactor (referred to as “the observed upper surface position of the content in the polymerization reactor” in the present invention) deviates significantly from the target upper surface position of the content in the polymerization reactor. When such an abnormal situation occurs, it may be difficult to quickly restore the observation upper surface position of the contents in the polymerization reactor to the target upper surface position with the above residence time control, which hinders stable operation. There is a risk of causing. When such an abnormal situation occurs, switching from the above residence time control to the upper surface position control (control of the discharge on-off valve based on the upper surface position of the contents in the polymerization reactor) in order to return to the normal state. preferable.
Specifically, when the allowable fluctuation range from the target upper surface position is set in advance as the “first management range” and the observation upper surface position of the contents in the polymerization reactor is out of the first management range, the residence time The discharge on / off valve is controlled by switching from the control to the upper surface position control. In addition, a “second management range” is preset in the first management range in a range narrower than the first management range, and the observed upper surface position of the contents in the polymerization reactor is within the second management range by upper surface position control. In the case of returning to the above, the control of the discharge on-off valve is performed by returning from the upper surface position control to the residence time control. By providing the second management range as a threshold value for returning from the upper surface position control to the residence time control, it is possible to perform stable control by reducing the frequency of switching between the upper surface position control and the residence time control.

  Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a process diagram showing an outline of a preferred embodiment of the method for producing a powder polymer of the present invention.

  The powder polymer production apparatus 1 continuously supplies a raw material monomer and a polymerization catalyst for generating a powder polymer to the polymerization reactor 2 in which the powder polymer exists, with stirring, and extracts the powder polymer from the polymerization reactor 2. This is a production apparatus for producing a powder polymer by continuously extracting the powder polymer from the mouth 14. The powder polymer production apparatus 1 has an automatic control device 3. The automatic control device 3 controls the residence time of the contents in the polymerization reactor and stably produces a powder polymer having a uniform particle size and shape. be able to.

The polymerization reactor 2 has a raw material monomer supply port 11, a catalyst supply port 12, a stirring blade 13, and a powder polymer extraction port 14. The polymerization reactor 2 may have a temperature adjusting jacket 15. Similarly to the method described in JP-A-11-236404, the polymerization temperature may be adjusted by latent heat of vaporization using an inert solvent.
A raw material monomer supply passage 21 is connected to the raw material monomer supply port 11, and the raw material monomer supply flow rate is adjusted by a raw material monomer supply opening / closing valve 22 provided in the raw material monomer supply passage 21. In the raw material monomer supply path 21, a raw material monomer supply flow rate detection means 23 is provided. The raw material monomer supply flow rate detecting means 23 detects the raw material monomer supply flow rate. A catalyst supply path 24 is connected to the catalyst supply port 12, and a catalyst supply flow rate is adjusted by a catalyst supply opening / closing valve 25 provided in the catalyst supply path 24. A catalyst supply flow rate detection means 26 is provided in the catalyst supply path 24. The catalyst supply flow rate detecting means 26 detects the catalyst supply flow rate.
The stirring blade 13 is rotatably supported in the polymerization reactor 2 and is rotated by the stirring blade drive mechanism 30. Torque detection means or power detection means 35 is connected to the stirring blade drive mechanism 30. Torque or power detection means 35 detects the torque or power required for stirring in the polymerization reactor 2. As the torque detection means or the power detection means 35, a torque meter, a dynamometer, or the like can be used.
A discharge passage 16 is connected to the powder polymer extraction port 14, and a discharge flow rate of the powder polymer is adjusted by a discharge opening / closing valve 50 provided in the discharge passage 16.
A powder polymer 80 is present in the polymerization reactor 2. The upper surface position 81 of the powder polymer 80 in the polymerization reactor 2 is detected by the upper surface position detecting means 40. Examples of the upper surface position detection means 40 include an ultrasonic detector, a microwave detector, a laser detector, a capacitance detector, and a γ-ray detector. Among these, a γ-ray detector is preferable.

  In the powder bed continuous bulk polymerization, the raw material monomer and the polymerization catalyst for generating the powder polymer are continuously supplied from the raw material monomer supply port 11 and the catalyst supply port 12 to the polymerization reactor 2 in which the powder polymer 80 exists. . At this time, while being stirred by the stirring blade 13, the raw material monomer absorbed in the powder polymer 80 as the seed polymer existing in the polymerization reactor 2 is polymerized, so that the powder polymer grows. The grown powder polymer is sequentially discharged from the powder polymer outlet 14 and collected via the discharge path 16.

  In the present invention, the discharge on / off valve 50 provided in the discharge passage 16 connected to the powder polymer outlet 14 is controlled so that the observed residence time of the contents 80 in the polymerization reactor 2 becomes the target residence time. Residence time control is performed. Preferably, the polymerization reaction is performed by controlling the mass of the content in the polymerization reactor by capturing the change in the bulk density of the content as at least the power or torque fluctuation that rotates the stirring blade in the polymerization reactor. Control the observation dwell time of the contents in the vessel. The observed residence time of the contents in the polymerization reactor can be calculated by the above equations (1) and (2), and the power or torque for rotating the stirring blade 13 in the polymerization reactor 2 is torque detection means or power. It is detected by the detection means 35.

Information on the supply flow rate of the raw material monomer detected by the raw material monomer supply flow rate detection means 23 is the raw material monomer supply flow rate signal S1, and the upper surface position 81 of the powder polymer 80 in the polymerization reactor 2 detected by the upper surface position detection means 40. Information relating to the power or torque detected by the torque detection means or power detection means 35 is sent to the automatic control device 3 as the upper surface position signal S2, respectively, as power / torque signal S3.
The automatic control device 3 can calculate the supply mass of the raw material monomer per unit time based on the raw material monomer supply flow rate signal S1, and calculate the volume of the contents in the polymerization reactor based on the upper surface position signal S2. The bulk density of the contents in the polymerization reactor can be calculated based on at least the power / torque signal S3.
The automatic control device 3 determines the opening degree of the discharge opening / closing valve 50 with reference to these signals, and sends the discharge opening / closing valve opening signal S4 to the opening / closing valve control means 55. The on / off valve control means 55 controls the opening of the discharge on / off valve 50 based on the discharge on / off valve opening signal S4. Further, the automatic control device 3 determines the opening degree of the raw material monomer supply opening / closing valve 22 and the catalyst supply opening / closing valve 25 provided in the raw material monomer supply path 21 and the catalyst supply path 24, respectively, together with the opening degree of the discharge on / off valve 50. You can also. When controlling the opening degree of the raw material monomer supply on / off valve 22 and the catalyst supply on / off valve 25, the automatic control device 3 sends a raw material supply on / off valve opening degree signal S5 to the on / off valve control means 27, and the on / off valve control means 27 The opening degree of the raw material monomer supply opening / closing valve 22 and the catalyst supply opening / closing valve 25 is controlled based on the raw material supply opening / closing valve opening signal S5.

  When the upper surface position 81 of the powder polymer 80 in the polymerization reactor 2 detected by the upper surface position detecting means 40 is out of the first management range, the automatic control device 3 switches from the residence time control to the upper surface position control. It is preferable to control the discharge on-off valve.

Switching between the residence time control and the upper surface position control by the automatic control device 3 will be described with reference to FIG. FIG. 2 is a schematic diagram for explaining switching between residence time control and top surface position control by the automatic control device.
In FIG. 2, the vertical axis indicates the observed upper surface position L of the contents in the polymerization reactor, and the horizontal axis indicates the polymerization time t. The first management range Ra is an allowable variation range from the target upper surface position L ₀ of the contents in the polymerization reactor, and is set as a range between the upper surface position La _{2 and} La ₁ . The second management range Rb is set in the first management range Ra as a range that is narrower than the first management range Ra and is between the upper surface positions Lb _{2 and} Lb ₁ . Lb ₁ is a value exceeding L ₀ and less than La ₁ , and Lb ₂ is a value exceeding La ₂ and less than L ₀ . Each value of La ₁ , La ₂ , Lb ₁ and Lb ₂ is appropriately set according to the apparatus.

FIG. 2 shows that the observed upper surface position L deviates from the first management range Ra from the state in which the observed upper surface position L of the contents substantially coincides with the target upper surface position L ₀ , and then returns to the second managed range Rb. The time-dependent change of the observation upper surface position L to the state is shown.

From the time point t _{0 to} the time point just before t ₁ , the observation upper surface position L is less than the upper surface position La ₁ and is within the first management range Ra, so that the residence time control is performed. At time t ₁ (P ₁ ) when the observed upper surface position L is equal to or higher than the upper surface position La ₁ and deviates from the first management range Ra, the automatic control device 3 switches from the residence time control to the upper surface position control, and the discharge on / off valve 50 And the discharge opening / closing valve opening signal S4 is sent to the opening / closing valve control means 55. The on / off valve control means 55 controls the opening of the discharge on / off valve 50 based on the discharge on / off valve opening signal S4. Further, the automatic control device 3 determines the opening degree of the raw material monomer supply opening / closing valve 22 and the catalyst supply opening / closing valve 25 provided in the raw material monomer supply path 21 and the catalyst supply path 24, respectively, together with the opening degree of the discharge on / off valve 50. You can also. When controlling the opening degree of the raw material monomer supply on / off valve 22 and the catalyst supply on / off valve 25, the automatic control device 3 sends a raw material supply on / off valve opening degree signal S5 to the on / off valve control means 27, and the on / off valve control means 27 The opening degree of the raw material monomer supply opening / closing valve 22 and the catalyst supply opening / closing valve 25 is controlled based on the raw material supply opening / closing valve opening signal S5.

Even if the observed upper surface position L is less than the upper surface position La ₁ , if it exceeds the upper surface position Lb ₁ , the upper surface position control is continued. At time t ₂ (P ₂ ) when the observed upper surface position L becomes equal to or lower than the upper surface position Lb ₁ and returns to the second management range Rb, the automatic control device 3 returns to the residence time control from the upper surface position control, and the discharge on / off valve 50 Control.

Although not shown in FIG. 2, switching from the dwell time control to the upper surface position control is also performed when the observation upper surface position is La ₂ or less and deviates from the first management range Ra. When the observation upper surface position L becomes equal to or higher than the upper surface position Lb ₂ and returns to the second management range Rb, the upper surface position control is returned to the dwell time control.

  As mentioned above, although the preferable one embodiment of the powder polymer manufacturing method and manufacturing apparatus of this invention was demonstrated referring drawings, this invention is not limited to this.

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

Example 1
Polystyrene powder was charged into a 200 L polymerization reactor equipped with a stirring blade and a temperature control jacket so that the upper surface of the polystyrene reactor covered the top of the rotor blade. The catalyst component mixture was prepared in the same manner as in Example 1 of Japanese Patent No. 4503852 except that the solvent toluene concentration was reduced and the catalyst concentration was concentrated four times in Example 1 of Japanese Patent No. 4503852. After heating the inside of the polymerization reactor by passing warm water at 70 ° C. through the jacket, the styrene monomer and the catalyst component mixed solution were supplied at 13 L / hr and 0.3 L / hr, respectively, with stirring to initiate the polymerization. The residence time was controlled for 15 days from 5 days after the start of polymerization. Specifically, the fluctuation of the bulk density of the contents in the polymerization reactor is at least regarded as the fluctuation of the power or torque that rotates the stirring blade in the polymerization reactor, and the contents of the contents in the polymerization reactor are changed. The observed residence time of the contents in the polymerization reactor was controlled by controlling the mass to be constant. The bulk density of the powder polymer discharged from the discharge path every 4 hours was measured. The graph of the rate of change from the average value of the measured bulk density of the powder polymer is shown in FIG. The operation days 0 in FIG. 3 is the fifth day from the start of polymerization. In FIG. 3, the results in Example 1 are indicated by black circles. The standard deviation regarding the change rate of the bulk density at this time was 5.4%. In addition, standard deviations were calculated for the observed residence time of the powder polymer in the polymerization reactor, the total mass and the upper surface position, and the rate of change in torque required for stirring in the polymerization reactor. The results are shown in Table 1.

Comparative Example 1
A powder polymer was produced and evaluated in the same manner as in Example 1 except that the upper surface position control was performed instead of the residence time control in Example 1. That is, control was performed so that the upper surface position of the powder polymer in the polymerization reactor was constant. The evaluation results are shown in FIG. In FIG. 3, the results in Comparative Example 1 are indicated by black square marks.

As is clear from Table 1 and FIG. 3, in Comparative Example 1 in which the upper surface position control, which is a conventional method, was performed, the fluctuation range of the observed upper surface position of the powder polymer in the polymerization reactor was small, but the observed residence time was controlled. It can be seen that the fluctuation range of the torque required for stirring in the polymerization reactor is large, and there is a risk of hindering stable operation. Furthermore, the fluctuation range of the bulk density of the obtained powder polymer is large, and the particle size and shape uniformity of the obtained powder polymer are inferior.
On the other hand, in Example 1 in which the residence time was controlled, the fluctuation range of the bulk density of the powder polymer can be controlled to be small, and as a result, the fluctuation range of the residence time of the powder polymer can be controlled to be small. . In addition, the fluctuation range of the torque required for stirring in the polymerization reactor is small, and the apparatus can be stably operated.

  According to the present invention, in powder bed continuous bulk polymerization, the true residence time of the contents in the polymerization reactor can be controlled, and a powder polymer having a uniform particle size and shape can be stably produced. Can do.

DESCRIPTION OF SYMBOLS 1 Powder polymer manufacturing apparatus 2 Polymerization reactor 3 Automatic control apparatus 11 Raw material monomer supply port 12 Catalyst supply port 13 Stirring blade 14 Powder polymer extraction port 15 Jacket 16 Discharge path 21 Raw material monomer supply path 22 Raw material monomer supply on-off valve 23 Raw material Monomer supply flow rate detection means 24 Catalyst supply path 25 Catalyst supply on / off valve 26 Catalyst supply flow rate detection means 27 Open / close valve control means 30 Stirring blade drive mechanism 35 Torque detection means or power detection means 40 Upper surface position detection means 50 Discharge on / off valve 55 Open / close valve Control means 80 Powder polymer (contents in the polymerization reactor)
81 Upper surface position of powder polymer (upper surface position of contents in polymerization reactor)
L Observing upper surface position of contents in polymerization reactor L ₀ Target upper surface position Ra of contents in polymerization reactor First management range Rb Second management range S1 Raw material monomer supply flow rate signal S2 Upper surface position signal S3 Power / torque signal S4 Discharge on / off valve opening signal S5 Raw material supply on / off valve opening signal

Claims (9)

The raw material monomer for generating the powder polymer and the polymerization catalyst are continuously supplied to the polymerization reactor in which the powder polymer is present under stirring, and the powder polymer is continuously supplied from the powder polymer outlet of the polymerization reactor. A method for producing a powder polymer, comprising:
Residence for controlling the discharge on-off valve provided in the discharge passage of the powder polymer outlet so that the observed residence time of the contents in the polymerization reactor becomes the target residence time of the contents in the polymerization reactor Powder polymer manufacturing method for time control. The method for producing a powder polymer according to claim 1, wherein the observed residence time of the contents in the polymerization reactor is calculated by the following formulas (1) and (2).
(Observation residence time of contents in polymerization reactor) = (mass of contents in polymerization reactor) / (feed mass of raw material monomer per unit time) (1)
(Mass of contents in polymerization reactor) = (Volume of contents in polymerization reactor) × (Bulk density of contents in polymerization reactor) (2)   The powder density according to claim 2, wherein the bulk density of the contents in the polymerization reactor is calculated based on at least torque or power required for stirring in the polymerization reactor correlated with the bulk density. Body polymer manufacturing method.   The method for producing a powder polymer according to any one of claims 1 to 3, wherein a supply mass of the raw material monomer per unit time is made constant.   When the observed upper surface position of the contents in the polymerization reactor deviates from the preset first control range, the observed upper surface position is the contents in the polymerization reactor instead of the residence time control. The method for producing a powder polymer according to any one of claims 1 to 4, wherein upper surface position control for controlling the discharge on-off valve is performed so that the target upper surface position is reached.   When the upper surface position control is performed and the observed upper surface position returns to the second management range set to a range narrower than the first management range, the dwelling is performed from the upper surface position control. The method for producing a powder polymer according to claim 5, wherein the method is returned to time control.   The powder polymer production according to any one of claims 1 to 6, wherein the discharge on-off valve is controlled so that a standard deviation of a change rate of a difference between the observed residence time and the target residence time is 20% or less. Method.   The method for producing a powder polymer according to any one of claims 1 to 7, wherein the raw material monomer is styrene or propylene.   The powder polymer manufacturing apparatus which manufactures a powder polymer with the powder polymer manufacturing method in any one of Claims 1-8.

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