JPH0488001A - Method for continuous polymerization - Google Patents

Abstract

PURPOSE:To control polymerization degree with a high accuracy and carry out continuous polymerization by performing the polymerization in the former period to a specific rate of reaction and then polymerization in the latter period in a horizontal type polymerizer and a forced extruding reactor and subsequently regulating the flow rate of an inert gas so as to provide the polymer viscosity, etc., within the ranges of the target set values. CONSTITUTION:By-products, volatile components and solvents, etc., produced by reaction are distilled away in rectifying columns 3 and 3' and condensers 4, 4', 9 and 9' and polymerization is carried out. In the process, the polymerization stage (I) in the former period until the rate of reaction attains 20-90% leading to the prescribed reaction end point is carried out in low-viscosity polymerizers 2 and 2' and the polymerization stage (II) in the latter period to the completion of the reaction is performed by using a horizontal type polymerizer 8 and a forced extrusion reactor 13 by extrusion flow. An inert gas is introduced into the horizontal polymerizer 8 and the viscosity and/or melting point and/or softening point of the polymer are measured. A monomer is continuously polymerized while regulating the flow rate of the inert gas so that the aforementioned viscosity and/or melting point and/or softening point may be within the ranges of the target set values.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a continuous polymerization method using a horizontal polymerization device, and more specifically, to a method for introducing an inert gas into the polymerization device and polymerizing the produced polymer. This invention relates to a continuous polymerization method that accurately controls the polymerization rate.

[Conventional technology]

Conventionally, as a method for controlling the degree of polymerization when obtaining a polymer by continuous polymerization reaction, acceleration of polymerization by controlling the amount of inert gas introduced has been proposed in Japanese Patent Publication No. 5352597. This is a method used in the continuous polymerization method for caprolactam, in which the amount of distilled water is detected and the degree of polymerization is increased while controlling the amount of inert gas introduced so that this remains almost constant. However, in the late stage of polymerization, the change in the amount of distilled water is so small that it is difficult to detect the amount of change, and it is difficult to precisely control the degree of polymerization.

In addition, horizontal continuous polymerization apparatuses have been devised to perform polymerization of high viscosity systems. This consists of a cylindrical or elliptical container placed horizontally, equipped with stirring blades with excellent surface renewal ability, and designed to minimize the clearance between the stirring blades and the tank wall. This is a device in which polymerization is carried out in a polymerization tank while moving the polymer in the horizontal direction from the supply port to the take-out port using extrusion flow. However, it was difficult to control the final physical properties in the high viscosity region using only this device.

It has also been proposed to use an extruder type reactor as a device for carrying out polycondensation reactions and bulk polymerization reactions of polymers. For example, in Japanese Patent Publication No. 52-17555, an extruder type reactor is used in a method for producing a methyl methacrylate polymer containing 25 to 60% by weight of unreacted monomers, solvents, volatile components, etc. by removing the volatile components. However, in order to remove a large amount of volatile components using this device, there is a drawback that the device needs to be large because the space inside the device is small.

[Problem to be solved by the invention]

With conventional technology, in the late stage of the polymerization reaction, the rapid increase in the viscosity of the polymer causes the polymer to wrap around the stirring shaft or adhere in the reaction tank, making it impossible to stir and mix or extract the polymer. , or it was difficult to control the degree of polymerization of the polymer.

In addition, there are few manufacturing devices and manufacturing methods that can control the molecular weight distribution of polymers, and even if there are, they are only methods that narrow the molecular weight distribution of polymers, and only those that are designed to narrow the molecular weight distribution of polymers. There was no equipment or method that could easily produce a combination.

In addition, in the conventional technology, control factors (temperature, pressure, stirring speed, etc.)
It is difficult to accurately control the degree of polymerization of the polymer, and there has been a desire for a method that can overcome these difficulties and can be implemented easily and economically. .

[Means to solve the problem]

In order to solve the above-mentioned problems, the present inventors have solved the above problem by using a carrier gas, since the distillation amount of by-products, volatile components, and solvents used in the reaction in continuous polymerization reactions contribute to the degree of polymerization of the polymer. It has been found that the degree of polymerization of the polymer can be controlled quickly and with high precision by introducing an inert gas into the polymerization apparatus and adjusting its flow rate.

Furthermore, it has been found that the degree of polymerization of the polymer can be controlled by using a forced extrusion reactor capable of quantitatively discharging any high-viscosity polymer in the continuous polymerization method.

That is, the present invention is a continuous polymerization method in which polymerization is carried out while distilling by-products produced in the reaction, volatile components, solvents used in the reaction, etc., and the production process reaches a predetermined reaction end point.
An early polymerization step until a reactivity of 0 to 90% is reached;
In the latter stage polymerization step, a horizontal polymerization device using an extrusion flow and a forced extrusion reactor are used, and an inert gas is introduced into the horizontal polymerization device to control the viscosity and/or or melting point and/or
Alternatively, it relates to a continuous polymerization method characterized by measuring the softening point and adjusting the amount of inert gas introduced so that the softening point falls within a target set value range. In addition, the present invention is a continuous polymerization method in which polymerization is carried out while distilling by-products generated in the reaction, volatile components, solvents used in the reaction, etc., in which the production process reaches a predetermined reaction end point by 20 to 90%. The process consists of an early polymerization step until the reactivity is reached, and a late polymerization step until the reaction is completed. It is characterized by introducing the inert gas into the polymerization apparatus, measuring the load on the stirrer and/or outlet pump of the horizontal polymerization apparatus, and adjusting the amount of inert gas introduced so that these fall within the target set value range. It is related to continuous polymerization method.

As described above, in the present invention, the rapid increase in viscosity of the polymer in the late stage of polymerization is detected by the outlet viscosity of the reaction tank of the horizontal polymerization apparatus, the load of the stirrer of the reaction apparatus, etc., and these detected values are set as the set value. By adjusting the flow rate of the inert gas so that it falls within the range, the degree of polymerization of the polymer can be adjusted with high accuracy, and the operation at this time can be performed online or offline. There is also no particular limitation on the method of adjusting the gas flow rate.

As the inert gas introduced into the reaction system, any substance that does not affect the reaction and is a gas at the reaction temperature can be used, but N
2. Examples include He, Ar, etc., with nitrogen gas being particularly preferred. Such inert gases also serve to prevent deterioration of the polymerization product.

There are no particular limitations on the polymerization form and method of the polymerization reaction to which the present invention is applied. Polymerization reactions of polyurethane, phenol resin, alkyd resin, epoxy resin, silicone resin, etc. are preferred. In these polymerization methods, the reaction shifts to the production side by actively releasing the desorbed low molecules out of the system.

The reaction tank type in which the continuous polymerization reaction of the present invention is carried out is a horizontal polymerization apparatus, and it is preferable to use a polymerization apparatus that has a device type that can remove volatile components during the progress of the reaction and has a large gas-liquid interface area. more effective. In such a horizontal polymerization apparatus, when performing a continuous polymerization reaction, a continuous operation method is adopted in which raw materials are continuously fed into the apparatus at a constant rate and then discharged.

Inert gas is introduced by means of introduction whose flow rate can be controlled (
(including metered feed) into the reactor, and the gas flow rate (volume flow rate) is set according to the size of the reactor. If the amount is too small, there will be no effect, and if the amount is too large, there will be a lot of loss, making it uneconomical. The method of introduction is not particularly limited, but the introduction into the gas phase may be carried out in parallel or countercurrent to the flow direction, and the position and number thereof are not particularly limited.

In the present invention, physical properties such as viscosity of the polymer are measured, and measurement can be done online or offline, but online is usually preferable, and depending on the reaction form, it may be preferable to perform both. . Also, the measurement method is not particularly limited. Also, the melting point, softening point, etc. of the resin may be used as a substitute for the viscosity. Viscosity measuring methods include rotation, vibration, capillary type, drop type, etc., but are not particularly limited.

In the present invention, it is also possible to measure the load on the polymerization apparatus. In other words, the power of driving parts such as stirrers and outlet pumps,
The load can be measured by measuring the current value, torque value, shaft reaction force, etc.

Further, the degree of polymerization can be adjusted more precisely by measuring the viscosity of the polymer and the load on the polymerization apparatus drive section, and adjusting the flow rate of the inert gas so that both detected values fall within the set value range.

The horizontal polymerization device used in the present invention is a continuous polymerization device using extrusion flow, and has a drive parallel to the flow direction, which has substantially no mixing ability in the flow direction but has mixing ability in the radial direction. A continuous polymerization apparatus equipped with a stirring mechanism having a shaft is preferred. Such a continuous polymerization apparatus may be equipped with one or more polymerization precursor feed ports in the flow direction and at least one polymerization product outlet at the rear thereof. Using this device, the polymerization precursor is continuously dividedly supplied from multiple supply ports, the polymer is continuously stirred and transferred toward the polymerization product outlet without back-mixing, and then the polymerization precursor is fed at a certain position. The polymerization product can be continuously taken out from the takeout port installed in the holder to obtain a polymer with a controlled molecular weight distribution.

Alternatively, it may be provided with at least one polymerization precursor supply port, a plurality of polymerization product outlet ports in the flow direction, and a mixing device for the polymerization products.

Using this continuous polymerization device, the polymerization precursor is continuously supplied from the supply port, and the polymer is continuously stirred and transferred toward the polymerization product output port without back-mixing, and then multiple polymerizations are performed. It is possible to continuously take out the product in portions from the product take-out port, and then mix the separated polymerization products to obtain a polymer with a controlled molecular weight distribution.

Polymerization reactions whose degree of polymerization can be controlled by the polymerization apparatus and polymerization method of the present invention include radical polymerization reactions such as polystyrene, and polycondensation reactions such as polyester and polyamide. The polymerization precursor supplied from the supply port of the continuous polymerization apparatus is a monomer or a mixture thereof, a low molecular weight compound produced by a reaction between monomers, ie, a prepolymer, etc., and is a homogeneous polymer containing monomer units involved in polymerization.
composition or homogeneous mixture.

It is also possible to add various powders such as dyes and pigments and polymer property improvers, if necessary.

The continuous polymerization method of the present invention is divided into an early polymerization step until a reactivity of 20 to 90%, which is the predetermined reaction end point, is reached, and a latter polymerization step until the reaction is terminated. This early polymerization step is a polymerization step performed before the main reaction, and the type of reactor, operating conditions, etc. are not particularly limited.

In the present invention, the polymerization precursor supplied to the horizontal polymerization apparatus through such an early polymerization step is conveyed to the product outlet in the form of an extrusion flow. Here, the extrusion flow refers to a flow in which there is sufficient mixing in a plane perpendicular to the flow direction, and there is substantially no mixing (back mixing) along the flow direction. In the present invention, it is essential to use an extrusion flow in order to improve the controllability of the degree of polymerization. This is because when back mixing occurs, it becomes difficult to control the degree of polymerization of the polymer.

The stirring mechanism that satisfies the above conditions is a mechanism that does not cause back mixing and is used in bulk polymerization reactions, such as a negative-axis forward direction screw, multi-stage rotating disk, paddle, etc., or a multi-axis forward direction screw, etc. Particularly favorable effects can be obtained by using a screw, a multi-stage rotating disk, a paddle, etc. (A screw that is twisted in the direction of transport in the flow direction during normal rotation will be referred to as a forward screw).

In the present invention, by using a horizontal polymerization apparatus having a plurality of supply ports and/or a plurality of discharge ports, it is possible to easily produce a polymer having a specific distribution of molecular weight. It is possible. Further, the forced extrusion reaction device may be provided with a plurality of supply ports.

Next, an example of a reaction apparatus used in carrying out the present invention will be explained in detail with reference to FIG. This reactor has a first polymerization step I consisting of one tank or several types, a supply port for a low molecular weight product produced in the first polymerization step, 7 in FIG. 1, and a plurality of outlets 11 for high molecular weight products. The latter stage polymerization step (2) consists of a horizontal polymerization tank 8 whose fluid state is an extrusion flow and a forced extrusion reaction device 13.

Figure 1 shows an example in which the polymerization reaction is carried out in a continuous manner in the early polymerization step and the latter polymerization step. A semi-patch method is also possible. Of the above two methods, the former is advantageous for mass production as it allows for automatic operation, while the latter is a semi-patch method, requiring almost no time to reach a steady state, making it easier to change product types. This method is advantageous for high-mix, low-volume production since there is little product loss during production.

A specific example of the structure of the first stage polymerization step will be explained based on FIG.

Part (2) is a reaction tank row 2.2" equipped with a rectification column 3.3", a condenser 4.4", an agitator, a transfer pump 6.6" and a pressure control section 5.5", and is preferably It is preferable to have excellent mixing performance regardless of fluctuations in retention amount. In addition, the latter stage polymerization step
It consists of a horizontal polymerization tank 8 with an extrusion flow capable of handling high viscosity, and a forced extrusion reactor 13 equipped with a transfer pump 16, 16', a condenser 9' and a pressure control section 10'. Controlling the molecular weight distribution in a horizontal polymerization tank depends on the method of supplying low molecular weight substances and/or the method of taking out high molecular weight substances, but when controlling the molecular weight by this feeding method, the control of the supply port of low molecular weight substances The number is arbitrary, but there is no point in having too many. Considering the balance with the number of stages of stirring blades and the ease of operation of distributing the supply amount of polymerization precursor, it is recommended to set 2 to 30 locations in the flow direction. It is preferable that the interval between the supply ports be arbitrarily selected according to the desired molecular weight distribution.On the other hand, when the molecular weight distribution is controlled by the take-out method, it has the same meaning as when it is controlled by the supply method. It is not effective if there are too many take-out ports, and it is preferable to have 2 to 20 take-out ports in the flow direction.The shortest distance between the supply port and the take-out port is the minimum value on the high molecular weight side of the molecular weight of the obtained polymer. is a determining factor,
When the purpose is to obtain a high molecular weight product, it is not preferable that the length is too short.

The supply amount of the polymerization precursor from the plurality of supply ports can be distributed depending on the molecular weight distribution of the target polymer, by using one of the plurality of supply ports installed, and/or by using one of the plurality of supply ports installed. Or by using a flow control valve. In the case of extraction from a plurality of extraction ports, adjustment is made in exactly the same manner depending on the molecular weight distribution of the target polymer.

The supply from the horizontal polymerization tank 8 to the forced extrusion reactor is preferably carried out when the polymer viscosity reaches a high viscosity of 1000 cP or more. That is, the outlet 11 of the horizontal polymerization tank 8
The high viscosity polymer taken out is further introduced by a transfer pump 16 into a forced extrusion reactor, such as a back type reactor, a continuous kneader, a static mixer having a pushing device, preferably an extruder type reactor 13, and is continuously extruded. The polymer is extruded and transported to continue the polymerization reaction.

Next, a method for controlling the polymerization degree of a polymer using an inert gas in the latter stage polymerization step of the present invention will be explained with reference to the drawings.

FIG. 2 is a schematic diagram showing a flow sheet of a horizontal polymerization apparatus used in the present invention, in which 21 is a horizontal polymerization tank, 22
23 is a metering pump for extracting the polymerization product; 23 is a viscometer; 2
4 is a gas flow rate adjustment device, 25 is an agitator motor, 26 is a gas flow rate control device based on drive unit load, 26'' is a gas flow rate control device based on viscosity, 27 is a condenser, 28
29 is a polymerization raw material inlet, 29 is a polymer outlet, 30 is an inert gas inlet, and 31 is a stirring blade.

In the present invention, the viscosity (softening point, melting point) of the exit polymer
is measured by the viscometer 23, and inert gas such as N2 gas is introduced from the inlet 30 via the gas flow rate controller 26' and the gas flow rate regulator 24 so that the measured value falls within the target set value range. Adjust amount. Alternatively, the load on the stirrer motor 25 or pump 22 is measured as a drive motor current value or a torque value by a torque detector, and the gas flow rate controller 2 is adjusted so that this measured value falls within the target set value range.
The amount of inert=16 gas introduced from the inlet 2Ω is adjusted by the gas flow rate adjusting device 24 via the inert gas flow rate adjusting device 24 via the inert gas flow rate adjustment device 24 via the inert gas flow rate adjustment device 24 via the inert gas flow rate adjusting device 24. The degree of polymerization of the resulting polymer can be easily adjusted.

Furthermore, in the horizontal polymerization apparatus used in the present invention, low molecular weight by-products such as water and alcohol are generated during polycondensation, so a heating and extraction mechanism is required to distill them off. be. An exhaust port can also be provided as a mechanism for extracting this by-product or low-molecular volatile material. For heating, a heat transfer mechanism such as a heat medium jacket may be provided outside the polymerization apparatus and/or inside the stirring shaft. Such heat transfer mechanisms can also be used for heat removal in cases such as radical polymerization.

The molecular weight distribution of the polymerization product can be controlled by changing the rotational speed of the agitation transfer mechanism in addition to controlling the tank internal temperature, pressure, supply amount balance, or balance of the amount of polymerization product taken out.

〔Example〕

The present invention will be explained in more detail with reference to Examples below.
The present invention is not limited to these examples.

Note that parts in the examples are parts by weight.

Example 1 The first stage polymerization step consisted of two stages of continuous tank type reaction tanks each having a tank volume of 50β, and the second stage consisted of a horizontal polymerization tank with a tank volume of 40j2 and an extruder type reaction device with a space volume of 1.5j2. A polyester polymer was produced using the apparatus shown in FIG. 1, which is constructed by a polymerization process. Terephthalic acid 12.5 parts and succinic acid 9.0 parts were used as acid components, and polyoxypropylene (2.2 parts) was used as alcohol component.
)2.2-His(4-hydroxyphenyl)furopane 7
5 parts and 0.3 parts of stannous oxide as a reaction catalyst in a total amount of 20 kg/Hr at raw material supply port 1.
supplied to. In the first polymerization step, the reaction temperature was set at 220°C.
The pressure was controlled to be normal pressure in the first tank and approximately -500 mmHg in the second tank. Further, the reaction time was 2 hours for both the first tank and the second tank, and the esterification reaction rate was 70%.

Subsequently, in the late polymerization step, the reaction temperature of the horizontal polymerization tank was increased to 21°C.
0℃, reaction temperature of extruder type reactor 215℃
The low molecular weight product obtained in the previous polymerization step was supplied to the horizontal polymerization tank. Furthermore, the polymer reacted in the horizontal polymerization tank was continuously supplied to an extruder type reaction tank. In addition, as a horizontal polymerization tank, the apparatus shown in Fig. 2 was used.
The target setting value of the softening point of the exit polymer (measured with a flow tester made by Takashi) is 120°C, and the softening point is 120 ± 0.
．． The softening point was controlled by controlling the N2 flow rate, which is a control factor of the present invention, with a control operation range outside the range of 5°C.

During this period, the fluctuations in the resin softening points of the polymer at the outlet of the horizontal polymerization tank and the polymer at the outlet of the extruder type reactor obtained from one week of continuous operation were 120±1℃ and 150±1℃, respectively.
It was ℃. Further, the esterification reaction rate of the polymer at the outlet of the extruder type reactor was 93%, and the polymer had an excellent color tone. The degree of esterification reaction in the first polymerization step of this example was 75.3%. Here, the softening point is measured using a Koka type flow tester (CFT-500, manufactured by Takasugi Seisakusho), with a die pore diameter of 1 mm, length of 1 mm, and a load of 20 kg.
The softening point is defined as the temperature corresponding to the height of 172 from the start point to the end point when a 1 cm3 sample is melted and flowed out under conditions of a temperature increase rate of 6° C./cm2 and a temperature increase rate of 6° C./min.

〔Effect of the invention〕

By detecting the viscosity (melting point, softening point) of the polymer and/or the load on the drive unit and adjusting the gas flow rate of the inert gas, it is possible to control the degree of polymerization quickly and with high precision. easy to operate, and other operating factors (temperature, degree of vacuum,
(retention amount, stirring speed, etc.). Furthermore, by introducing an inert gas, it is possible to prevent deterioration of the polymer and stabilize its quality. In particular, according to the present invention, the degree of polymerization of a high viscosity polymer can be controlled by using a forced extrusion reactor capable of quantitatively discharging any high viscosity polymer.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a flow sheet of an example of a continuous polymerization apparatus used in the present invention, and FIG. 2 is a schematic diagram showing a flow sheet of a horizontal polymerization tank portion thereof. ■... Early polymerization step ■... Late polymerization step 1.1'... Raw material supply section 2.2''... Low viscosity polymerization tank 3.3'... Rectification column 4.4'', 9.9'...Condenser 5, 5'
, 10.10"...Pressure control section 6, 6',
16.16'...Transfer pump 7...Low molecular weight substance supply port and flow rate control unit...Horizontal polymerization tank 11...High molecular weight substance outlet and flow rate control unit 12.
...Cooler 13...Forced extrusion reaction device 21...Horizontal polymerization tank 22...Polymerization product extraction metering pump 23...
Viscometer 24...Gas flow rate adjustment device 25...Agitator motor 26...Gas flow rate control device 26'' by drive unit load
...Viscosity-based gas flow rate control device 27...Condenser 28...Polymerization raw material inlet 29...Polymer outlet 30...Inert gas inlet 31...Agitator blade

Claims (1)

[Scope of Claims] 1. In a continuous polymerization method in which polymerization is carried out while distilling by-products generated in the reaction, volatile components, solvents used in the reaction, etc., from 20 to 20 when the manufacturing process reaches a predetermined reaction end point. 90
The process consists of an early polymerization step until a reactivity of 10% is reached, and a later polymerization step until the reaction is completed. A continuous method characterized by introducing the polymer into a horizontal polymerization apparatus, measuring the viscosity and/or melting point and/or softening point of the polymer, and adjusting the amount of inert gas introduced so that these fall within the target set value range. Polymerization method. 2 In a continuous polymerization method in which polymerization is carried out while distilling by-products generated in the reaction, volatile components, solvents used in the reaction, etc., the manufacturing process reaches a predetermined reaction end point from 20 to 90 days.
The process consists of an early polymerization step until a reactivity of 10% is reached, and a later polymerization step until the reaction is completed. A continuous method characterized by introducing the inert gas into a horizontal polymerization apparatus, measuring the load on the stirrer and/or outlet pump of the horizontal polymerization apparatus, and adjusting the amount of inert gas introduced so that these fall within the target set value range. Polymerization method.