Method and apparatus for manufacturing polymer

Abstract

To provide a method for manufacturing polymer by which it is possible to sufficiently prevent attachment to an inner wall of a reaction vessel on the basis of simple temperature control.SOLUTION: A method for manufacturing polymer includes subjecting a granular raw material to solid phase polymerization at a temperature higher than a temperature of an inner wall of a reaction vessel by heating the granular raw material by microwave while keeping the temperature of the inner wall of the reaction vessel lower than a polymerization temperature of the granular raw material in the reaction vessel with a microwave generator.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method and an apparatus for producing a polymer, and more particularly to a method and an apparatus for producing a polymer by a solid-state polymerization method. [Background technology]

[0002] Solid-state polymerization is widely used industrially in the production of polymers such as polyesters and heat-resistant polyamides. In solid-state polymerization, for example, a method in which raw material salt or prepolymer powder is heated at a temperature below the melting point of the polymer to be produced is common. Heating is mostly done by heat transfer from the inner wall of a high-temperature reaction vessel (Patent Document 1). Since solid-state polymerization allows production at a lower temperature than melt polymerization, it is possible to prevent thermal degradation of the polymer during polymerization. In addition, solid-state polymerization has the advantage that the molecular weight of the produced polymer can be increased by concentrating reactive active sites in the amorphous region due to crystallization.

[0003] However, the solid-state polymerization method has a problem in that the polymer is easily attached to the inner wall of the reaction vessel during production. When the attachment occurs, the heat transfer from the reaction vessel to the powdered raw material is hindered. Since the heat transfer efficiency from the inner wall of the reaction vessel is low for powdered materials compared to liquids, the decrease in the amount of heat transfer due to the attachment directly leads to a decrease in the productivity of the polymer. Furthermore, if the amount of attachment increases with repeated production, the polymerization conditions will fluctuate over time, and the quality of the polymer will decrease. Furthermore, in polymerization reactions, powdered materials generally tend to strongly solidify with each other, so that it is not easy to remove the attached matter. For these reasons, the prevention of the attachment is a major issue in the production and development of polymers by the solid-state polymerization method.

[0004] The adhesion of powder to the inner wall of a reaction vessel occurs through the following mechanism. When the powder raw material comes into contact with the inner wall of the reaction vessel (the degree of adhesion is not very strong at this stage), the polymerization reaction proceeds quickly because the contact surface, the inner wall of the reaction vessel, is the hottest. It is thought that the adhesion grows under conditions where the solidification between particles due to the polymerization reaction takes precedence over the movement of particles due to stirring or gravity.

[0005] On the other hand, if the temperature of the inner wall of the reaction vessel can be kept below the polymerization temperature, it is believed that adhesion due to the above mechanism will not occur. However, if the temperature of the inner wall of the reaction vessel is lowered, it is natural that the temperature of the powdered raw material cannot be raised to the temperature required for polymerization by heat transfer from the reaction vessel.

[0006] Therefore, Patent Document 2 discloses a technique for heating powdered raw material by using heat generated by stirring using a stirring blade. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2016-079203 A [Patent Document 2] WO2017 / 208857A1 Summary of the Invention [Problem to be solved by the invention]

[0008] However, when the technology of Patent Document 2 is used to produce polymers on a larger scale, temperature control may become difficult due to changes in frictional heat caused by changes in the shape of the powder or granules during the reaction system, making it necessary to raise the temperature of the inner wall of the reaction vessel, which may result in increased adhesion of the powder or granules to the inner wall of the reaction vessel.

[0009] In view of the above problems, the present invention has an object to provide a method and apparatus for producing a polymer by solid-state polymerization that fundamentally solves the problem of adhesion to the inner wall of a reaction vessel and is applicable to many types of polymers.

[0010] In particular, an object of the present invention is to provide a polymer production method and production apparatus that can sufficiently prevent adhesion to the inner wall of a reaction vessel based on simple temperature control. [Means for solving the problem]

[0011] The present inventors have conducted extensive research to solve these problems, and as a result have focused on the use of microwaves to supply the insufficient heat source. The present inventors have found that the above object can be achieved by heating the powdered or granular raw material with microwaves while maintaining the temperature of the inner wall of a reaction vessel lower than the polymerization temperature, and have arrived at the present invention.

[0012] That is, the gist of the present invention is as follows. <1> A method for producing a polymer, comprising the steps of: heating a powdered or granular raw material with microwaves in a reaction vessel equipped with a microwave generator, while maintaining the temperature of the inner wall of the reaction vessel lower than the polymerization temperature of the powdered or granular raw material, and performing solid-state polymerization at a temperature higher than the temperature of the inner wall of the reaction vessel. <2> The polymer is a polyamide. <1> A method for producing the polymer described in <3> The polymer is a polyamide comprising a dicarboxylic acid and a diamine, and 50 to 100 mol % of the dicarboxylic acid is terephthalic acid. <2> A method for producing the polymer described in <4> The method is characterized in that solid-state polymerization is carried out while detecting at least one of the temperature of the powdered raw material and the load of the agitator, and changing the microwave output and / or the temperature of the inner wall of the reaction vessel. <1> ~ <3> 3. A method for producing the polymer according to any one of claims 1 to 2. <5> In order to prevent runaway of the reaction system due to an excessive increase in condensed water of powder or granules, the method is characterized in that solid-state polymerization is carried out while changing the microwave output and / or the temperature of the inner wall of the reaction vessel, while detecting at least one of the temperature of the powder or granule raw material, the load of the agitator, and the amount of water discharged to the outside. <1> ~ <3> 3. A method for producing the polymer according to any one of claims 1 to 2. <6> An apparatus for producing a polymer, comprising: The manufacturing apparatus has a reaction vessel equipped with a microwave generator, The manufacturing apparatus is characterized in that the manufacturing apparatus heats the powdered or granular raw material with microwaves and polymerizes it in a solid state at a temperature higher than the temperature of the inner wall of the reaction vessel while maintaining the temperature of the inner wall of the reaction vessel lower than the polymerization temperature of the powdered or granular raw material. Effect of the Invention

[0013] According to the production method of the present invention, the solid-state polymerization is carried out while maintaining the temperature of the inner wall of the reaction vessel lower than the polymerization temperature of the powdered or granular raw material, so that the polymerization reaction is unlikely to proceed even if the powdered or granular raw material comes into contact with the inner wall of the reaction vessel, and therefore, adhesion of the powdered or granular raw material to the inner wall of the reaction vessel can be prevented. Furthermore, according to the production method of the present invention, the reaction time is shortened and productivity is improved.

[0014] The manufacturing method of the present invention heats the powdered or granular raw material with microwaves, and therefore, unlike methods that use the heat of stirring to control the temperature by changing the rotation speed of the stirrer, the method can easily control the temperature without being affected by changes in frictional heat that accompany changes in the shape of the powdered or granular material during the reaction. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic structural diagram of an example of a polymer production apparatus according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] FIG. 1 shows a schematic structural diagram of an example of a polymer production apparatus useful for carrying out the polymer production method according to the present invention. As shown in FIG. 1, the polymer production apparatus according to the present invention has a reaction vessel 2 equipped with a microwave generator 1. Therefore, in the polymer production method and production apparatus according to the present invention, the powdered raw material 10 can be heated with microwaves and easily polymerized in solid phase at a temperature higher than the temperature of the inner wall of the reaction vessel 2 while keeping the temperature of the inner wall of the reaction vessel 2 lower than the polymerization temperature of the powdered raw material 10. In the present invention, solid phase polymerization is a polymerization method in which a polymerization reaction proceeds in a solid phase state, and the reaction proceeds not only with the raw material used but also with the polymer produced in a solid phase state. In solid phase polymerization, the polymerization reaction usually proceeds based on heat.

[0017] The microwave generator 1 is not particularly limited as long as it generates microwaves (electromagnetic waves) with a frequency of, for example, 300 MHz to 300 GHz (particularly, 900 MHz to 3 GHz). From the viewpoint of controlling the temperature of powder or granule, it is preferable to use a microwave generator whose output can be adjusted. For example, when processing about 30 kg of powder or granule (e.g., raw material such as polyamide salt), it is preferable that the output of the microwave generator is variable within a range of, for example, 0.1 to 10 kW (particularly, 0.5 to 3 kW).

[0018] The reaction vessel 2 is usually also equipped with an agitator 21 and a temperature control device 22. The agitator 21 has an agitator blade and is not particularly limited as long as it can perform agitation to such an extent that the powder / granular material 10 (plural raw materials) and the temperature distribution in the reaction vessel 2 can be uniform. For example, the rotation speed of the agitator blade in the agitator 21 may be 10 to 70 rpm (particularly 50 to 70 rpm), and such a rotation speed is a rotation speed at which heat (i.e., agitation heat) due to agitation or the agitator blade is not substantially generated. Specific examples of the reaction vessel 1 include devices such as a Henschel mixer, a Super mixer, a Cyclomix, and a Loedige mixer.

[0019] The temperature control device 22 is a device for controlling the temperature of the inner wall of the reaction vessel 2. From the viewpoint of controlling the temperature of the inner wall of the reaction vessel 2, the temperature control device 22 is preferably a jacket type that is attached to the outside of the reaction vessel 2. Specific examples of the jacket type temperature control device include a heat medium type in which a heat medium 22 such as oil or steam flows in from an inlet 221 and flows out from an outlet 222, as shown in FIG. 1, and a heating element type in which a heating element such as an electric heating wire generates heat. The inner wall temperature of the reaction vessel 2 can be controlled by adjusting the temperature of the heat medium 22 (or the heating element).

[0020] The polymer production apparatus may further include a condenser 3. The condenser 3 is a device that converts the water introduced into the reaction vessel 2 and the water generated by the condensation reaction of the raw materials from a gaseous state to a liquid state by cooling, and recovers the water. The cooling medium is not particularly limited, and may be, for example, a fluid (e.g., water, air, nitrogen) at room temperature (25°C) or lower. The condenser 3 preferably includes a recovery tank 30, so that the amount of recovered water can be measured and observed.

[0021] The powdered raw material 10 is a raw material for polymers such as monomers, salts, and prepolymers, and is a powder in a solid state at the reaction temperature (i.e., polymerization temperature). On the other hand, the polymer obtained by solid-phase polymerization is also a solid powder at the reaction temperature (i.e., polymerization temperature). The powdered raw material may be one component or a mixture of multiple components. In the present invention, at least one raw material of the powdered raw material 10 may be in a solid state at the reaction temperature (i.e., polymerization temperature), but from the viewpoint of more sufficiently preventing adhesion to the inner wall of the reaction vessel, it is preferable that all of the powdered raw materials 10 are in a solid state at the reaction temperature (i.e., polymerization temperature). There is no limitation on the size of the powdered raw material, but the average particle size is preferably 5 mm or less, for example, 1 to 1000 μm, and particularly 10 to 300 μm. The present invention can be used even if the average particle size exceeds 5 mm, but powdered raw materials with an average particle size of 5 mm or more are difficult to adhere to the reaction vessel 1 in the first place. The powdered raw material may be pellets.

[0022] The powdered or granular raw material may be a mixture of multiple components. The powdered or granular raw material may further contain an end-capping agent, a catalyst, and other additives as necessary, and may be partially liquid in the form of a mixture of components.

[0023] The polymer is not particularly limited as long as it is a polymer that can be produced by solid-state polymerization, and for example, a polymer that can be produced by a solid-state polymerization reaction based on a condensation reaction is preferable. Examples of such a preferable polymer include polyamide and polyester. The polymer is preferably polyamide from the viewpoint of more sufficiently preventing adhesion to the inner wall of the reaction vessel.

[0024] When producing polyamide as a polymer, the powder raw material may specifically be a powder such as polyamide salt (polyamide 66 salt, polyamide 10T salt), polyamide oligomer (polyamide 10T oligomer, polyamide 9T oligomer, polyamide 6T oligomer), and raw monomer mixture of each polyamide (for example, a mixture of dicarboxylic acid and diamine). Considering that the raw material is solid at the reaction temperature, the raw material monomer is preferably a powder of aminocaproic acid or various polyamide salts (polyamide 66 salt, polyamide 1010 salt, polyamide 6T salt, polyamide 9T salt, polyamide 10T salt, polyamide 12T salt, etc.). The polyamide salt is a salt as a monomer mixture constituting the polyamide, and may be, for example, a salt of dicarboxylic acid and diamine. It is also preferable to use a polyamide oligomer or a low polymerization degree body as the powder raw material. In this case, polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide 6T, polyamide 9T, polyamide 10T, polyamide 12T, etc. are used in the form of powder or pellets.

[0025] Among polyamides, the present invention can be preferably applied to semi-aromatic polyamides, which are usually produced by solid-state polymerization. Semi-aromatic polyamides, which are polyamides made of dicarboxylic acids and diamines, and in which 50 to 100 mol % of the dicarboxylic acid is terephthalic acid, are more preferable because they can be used as raw materials for products with excellent heat resistance and mechanical properties.

[0026] When polyester is produced as a polymer, specific examples of the powdery raw material include a mixture of raw monomers for polyester (e.g., a mixture of terephthalic acid and ethylene glycol), oligomers, and low polymerization products. The type of polyester is not particularly limited, and an example thereof is polyethylene terephthalate (PET).

[0027] The present invention is equally applicable to polyamides, polyesters, or other polymers, whether homopolymers or copolymers.

[0028] In the present invention, it is necessary to heat the powdered raw material 10 with microwaves and perform solid-state polymerization at a temperature higher than the inner wall temperature of the reaction vessel 2 while maintaining the inner wall temperature of the powdered raw material 10 lower than the polymerization temperature of the powdered raw material 10. This makes it possible to sufficiently prevent adhesion to the inner wall of the reaction vessel. In this case, it is preferable to perform solid-state polymerization while changing the microwave output and / or the temperature of the inner wall of the reaction vessel while detecting at least one of the temperature of the powdered raw material and the load of the agitator (agitation power value). If the powdered raw material 10 is solid-state polymerized at a temperature lower than the inner wall temperature of the reaction vessel 2, adhesion to the inner wall of the reaction vessel cannot be sufficiently prevented. If microwaves are not irradiated, the powdered raw material 10 cannot be solid-state polymerized at a temperature higher than the inner wall temperature of the reaction vessel 2. For example, by detecting the load of the agitator (agitation power value) together with or instead of the temperature of the powdered raw material, when the load of the agitator (agitation power value) exceeds a predetermined value, the formation of agglomerates due to runaway of the reaction system becomes clear. In this case, the microwave output is reduced or stopped before the load on the agitator exceeds a predetermined value, so that the powder / granule temperature falls below the polymerization temperature and the reaction is stopped quickly. When the powder / granule temperature falls below the temperature of the inner wall of the reaction vessel 2, the microwave output is slowly increased to the original output value or to an output value lower than the original output value to restart the reaction. In this way, the reaction can proceed in a powder / granule state without forming lumps.

[0029] The difference (Ta-Tb) between the polymerization temperature (Ta (°C)) of the powdered or granular raw material 10 and the inner wall temperature (Tb (°C)) of the reaction vessel 2 is not particularly limited as long as adhesion to the inner wall of the reaction vessel is prevented, and may be, for example, 1°C or more (particularly from 1 to 100°C). From the viewpoint of more sufficiently preventing adhesion to the inner wall of the reaction vessel, the difference (Ta-Tb) is preferably 5°C or more (particularly from 5 to 70°C), more preferably 8°C or more (particularly from 8 to 40°C), particularly preferably 10°C or more (particularly from 10 to 30°C), and sufficiently preferably 15°C or more (particularly from 15 to 30°C).

[0030] The polymerization temperature (Ta) of the powdered or granular raw material 10 is a temperature lower than the melting point (Mp (°C)) of the polymer produced, and may be, for example, Mp-160 to Mp-30 (°C). From the viewpoint of more sufficiently preventing adhesion to the inner wall of the reaction vessel, it is more preferably Mp-130 to Mp-30 (°C), even more preferably Mp-100 to Mp-35 (°C), particularly preferably Mp-80 to Mp-40 (°C), sufficiently preferably Mp-80 to Mp-50 (°C), and even more preferably Mp-75 to Mp-60 (°C). Specifically, when the polymer is polyamide (particularly polyamide 10T), the polymerization temperature (Ta) of the powdered or granular raw material 10 may be 150 to 280°C.

[0031] The melting point of the polymer produced (Mp (°C)) is the melting point of the target polymer, and more specifically, the melting point of the polymer obtained by sufficiently polymerizing the monomers constituting the target polymer. Therefore, when carrying out the method for producing a polymer of the present invention, first, the target polymer is obtained by sufficiently polymerizing only the monomers (which may be monomer salts or prepolymers) used as the raw materials. Next, the melting point of the target polymer is measured, and the polymerization temperature of the powdered granular raw material 10 for the solid-phase polymerization in the present invention and the inner wall temperature of the reaction vessel 2 may be determined or set based on the melting point. The polymerization method for obtaining the target polymer is not particularly limited as long as sufficient polymerization is performed, and for example, a melt polymerization method may be used. The melt polymerization method is a method in which polymerization is sufficiently performed by heating without using a solvent to obtain a polyamide resin in a molten state. In the melt polymerization method, for example, a device similar to the above-mentioned jacket-type temperature control device without a microwave generator may be used. The polymerization temperature in the melt polymerization method is, for example, 230 to 250°C (particularly 250°C) in the case of polyamide 10T, 230 to 250°C (particularly 240°C) in the case of polyamide 6, 250 to 290°C (particularly 280°C) in the case of polyamide 66, 220 to 240°C (particularly 230°C) in the case of polyamide 12, and 270 to 290°C (particularly 280°C) under high vacuum in the case of PET. The polymerization time in the melt polymerization method may be any time that allows sufficient polymerization, and may be, for example, 0.5 to 2 hours, particularly 1 hour, when a total of 30 kg of raw materials is used.

[0032] The polymerization temperature (Ta) of the powdered or granular raw material 10 refers to the temperature of the powdered or granular raw material 10 in the reaction vessel 2, and is preferably set to a polymerization temperature suitable for the polymer below the melting point of the polymer, taking into consideration productivity and quality. The temperature of the powdered or granular raw material can be controlled by changing the microwave output value. Specifically, by increasing the microwave output, the temperature of the powdered or granular raw material can be increased without changing the temperature of the inner wall of the reaction vessel. On the other hand, by decreasing the microwave output, the temperature of the powdered or granular raw material can be decreased without changing the temperature of the inner wall of the reaction vessel. The temperature of the powdered or granular raw material 10 (particularly the polymerization temperature) may be a temperature measured by a contact thermometer T1 near the middle position of the reaction vessel 2.

[0033] The inner wall temperature (Tb) of the reaction vessel 2 is preferably set to a temperature range where polymerization hardly proceeds (for example, a temperature lower than the polymerization temperature (Ta) of the powdered or granular raw material 10), and more preferably may be a temperature where the above-mentioned difference (Ta-Tb) is ensured. The temperature of the inner wall of the reaction vessel is preferably set to a temperature where polymerization can be performed, since the amount of adhesion to the inner wall of the reaction vessel is reduced. However, if the temperature of the inner wall of the reaction vessel is too low, the output value of the microwave must be increased to polymerize the powdered or granular raw material, compared to when the temperature is high. The inner wall temperature of the reaction vessel 2 can be controlled by adjusting the temperature of the heat medium or heating element of the temperature control device. For example, in the jacket-type heat medium type temperature control device 22, the temperature of the heat medium (for example, oil) measured by a contact type thermometer T2 arranged at the inlet 221 of the jacket may be used as the inner wall temperature (Tb) of the reaction vessel 2.

[0034] The polymerization temperature (Ta) of the powdered or granular raw material 10 and the inner wall temperature (Tb) of the reaction vessel 2 may be controlled independently of each other, or both may be controlled simultaneously.

[0035] Since the state of the material changes as the polymerization progresses, it is preferable to detect the load on the agitator. In particular, if the reaction proceeds too quickly, adhesion grows and the load on the agitator increases under conditions in which the solidification between particles due to the polymerization reaction takes precedence over the movement of particles due to stirring or gravity. Therefore, when the load on the agitator increases suddenly, it is advisable to reduce the microwave output value and / or the temperature of the inner wall of the reaction vessel to slow down the reaction rate.

[0036] In the present invention, when solid-state polymerization is performed while ensuring a temperature gradient (hereinafter sometimes referred to as a "specific temperature gradient") in which the polymerization temperature of the powdered or granular raw material 10 is higher than the inner wall temperature of the reaction vessel 2 as described above, it is not necessary to continuously ensure the temperature gradient throughout the entire time that the solid-state polymerization reaction proceeds. This is because, even if the specific temperature gradient is ensured for only 10 minutes when performing solid-state polymerization, adhesion to the inner wall of the reaction vessel can be more effectively prevented compared to when the specific temperature gradient is not ensured. From the viewpoint of more adequately preventing adhesion to the inner wall of the reaction vessel, the longer the time for performing solid-state polymerization with the specific temperature gradient, the more preferable, more preferably 0.5 hours or more, even more preferably 1 hour or more, particularly preferably 2 hours or more, sufficiently preferably 3 hours or more, and even more preferably 4 hours or more. At this time, the upper limit of the time for performing solid-state polymerization with the specific temperature gradient is not particularly limited, and for example, the time for performing solid-state polymerization with the specific temperature gradient may be 8 hours or less (particularly 6 hours or less). The time for performing solid-state polymerization with the specific temperature gradient is essentially the time for performing solid-state polymerization with the specific temperature gradient in the main polymerization stage and the finish polymerization stage of the solid-state polymerization process described later.

[0037] In the present invention, polyamide is produced through a preparation step in which the powder temperature reaches the reaction initiation temperature, and a solid-state polymerization step in which solid-state polymerization substantially proceeds. In this case, it is sufficient that a specific temperature gradient is ensured for at least a portion of the time in the solid-state polymerization step. The reaction initiation temperature is the temperature at which the polymerization reaction substantially starts, and in the present invention, Mp-96 (°C) is used. Mp is the above-mentioned "melting point of the polymer to be produced" (i.e., "melting point of the target polymer") Mp (°C). In this specification, the time at which the powder temperature reaches the reaction initiation temperature is called the reaction initiation time.

[0038] The solid-state polymerization process has a main polymerization stage in which heating is performed by microwaves, and a specific temperature gradient is ensured in the main polymerization stage, which is usually the stage until the discharge of condensation water stops.

[0039] The solid-state polymerization process may or may not have an initial polymerization stage in which heating is performed by a heating means other than microwaves prior to the main polymerization stage. The initial polymerization stage may be performed, for example, until the reaction rate reaches 40 to 60% (particularly 45 to 55%). The reaction rate is the ratio of the number of functional groups provided to the solid-state polymerization reaction to the total number of functional groups in the raw material, and may be the terminal reaction rate. From the viewpoint of more sufficiently preventing adhesion to the inner wall of the reaction vessel, it is preferable that the solid-state polymerization process does not have an initial polymerization stage.

[0040] In the solid-state polymerization process, after the main polymerization stage is performed, a final polymerization stage may be performed to further advance the solid-state polymerization reaction. The final polymerization stage is a stage performed after the drainage of the condensation water in the main polymerization stage has stopped. In the final polymerization stage, the specific temperature gradient in the main polymerization stage may or may not be ensured.

[0041] In the final polymerization stage, if necessary, the solid-state polymerization by microwave heating in the main polymerization stage can be followed by further polymerization by heating by general heat transfer. Adhesion to the reaction vessel occurs only in the first half of the polymerization reaction, and adhesion does not occur even if heating by heat transfer is performed as described above in the second half (particularly in the final polymerization stage). Therefore, the specific temperature gradient described above does not need to be ensured in the final polymerization stage.

[0042] According to the present invention, the reaction time is shortened and the productivity is improved compared to the case where the polymerization is carried out only by heat transfer from the inner wall of the reaction vessel. The effect of improving the productivity becomes more remarkable as the reaction vessel becomes larger. According to the present invention, the productivity is improved compared to the case where the polymerization is carried out only by heat transfer from the inner wall of the reaction vessel and the heat of stirring based on stirring. The effect of improving the productivity is also remarkable as the reaction vessel becomes larger.

[0043] When the present invention is applied to a condensation polymerization system for polyamide, water is generated from inside the powder as the reaction proceeds. Since the atmospheric temperature during polymerization is 100°C or higher, water is discharged to the outside of the system as water vapor. It is considered that water passes through a state of being captured inside the powder before becoming water vapor. As the reaction proceeds, the amount of water inside the powder increases, so the microwave loss coefficient of the powder increases. That is, the powder is more likely to absorb microwaves. Therefore, even if the microwave output value is the same, the amount of heat generated increases as the reaction proceeds. When the amount of heat generated increases, the polymerization reaction is further accelerated, and the reaction becomes accelerated, and the reaction system may run away and become difficult to control. In order to prevent the reaction system from running away due to an excessive increase in the amount of condensation water, solid-state polymerization may be performed while changing the microwave output while detecting at least one of the temperature of the powder raw material, the load of the agitator, and the amount of water discharged to the outside of the system.

[0044] Specifically, for example, if the temperature of the powdered or granular raw material suddenly rises and / or localized heating by microwaves occurs, causing clumps of material to form due to the polymerization reaction coagulating more than the movement of particles due to stirring or gravity, resulting in a sudden increase in the load on the stirrer. By reducing the microwave output and reducing the energy supply required for the reaction, the reaction system can be prevented from running out of control.

[0045] The polymer obtained by the manufacturing method of the present invention can be used in a method such as melt processing in the same manner as the polymer obtained by other known methods. For example, it can be used in injection molding applications. In that case, it is preferable to add additives such as fillers and stabilizers as necessary. The method of addition includes a method of adding during polymerization of a polymer (particularly polyamide) or a method of melt-kneading the obtained polymer (particularly polyamide). Examples of additives include fibrous reinforcing materials such as glass fiber and carbon fiber, fillers such as talc, swelling clay minerals, silica, alumina, glass beads, and graphite, and pigments such as titanium oxide and carbon black. Other additives include additives such as antioxidants, antistatic agents, flame retardants, and flame retardant assistants. In addition to injection molding, the above polymers can also be used as raw materials for fibers and films.

[0046] Applications of injection molded products include automobile parts used around the transmission, engine, and lamps of automobiles, and electrical and electronic parts for office equipment. Specifically, automobile transmission parts include base plates used for the pedestals of shift levers and gearboxes, engine parts include cylinder head covers, engine mounts, air intake manifolds, throttle bodies, air intake pipes, radiator tanks, radiator supports, radiator hoses, water pump inlets, water pump outlets, thermostat housings, cooling fans, fan shrouds, oil pans, oil filter housings, oil filter caps, oil level gauges, timing belt covers, engine covers, and lamp parts include lamp reflectors, lamp housings, lamp extensions, and lamp sockets. Electrical and electronic parts include connectors, LED reflectors, switches, sensors, sockets, capacitors, jacks, fuse holders, relays, coil bobbins, resistors, and housings for ICs and LEDs. Films include speaker diaphragms, film capacitors, and insulating films. Examples of the fibers include airbag base fabrics and heat-resistant filters. EXAMPLES

[0047] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these. The physical properties of polyamide were measured by the following methods.

[0048] (1) Terminal reaction rate Polyamide resin was analyzed using a high-resolution nuclear magnetic resonance apparatus (manufactured by JEOL Ltd., "ECA500 NMR") 1 The molar ratio of unreacted carboxylic acid end groups to unreacted amine end groups was determined by H-NMR analysis, and the proportion of unreacted amide bond end groups among the total of carboxylic acid end groups and amine end groups was calculated. The analysis conditions were as follows: Resolution: 500MHz Solvent: Deuterated trifluoroacetic acid Temperature: 30℃

[0049] (2) Amount of adhesion to the can wall After the polymerization was completed, the polyamide was discharged from the ribbon blender-type vessel, and the polyamide adhering to the can wall was scraped off to determine the amount of polyamide adhering to the can wall.

[0050] (3) Melting point Using a differential scanning calorimeter (PerkinElmer, "DSC-7"), 10 mg of polyamide resin was heated from room temperature to 350°C at a rate of 20°C / min and held for 5 minutes. The temperature was then lowered to 25°C at a rate of 500°C / min, held at 25°C for 5 minutes, and then heated to 400°C at a rate of 20°C / min. The apex of the peak resulting from melting in the curve obtained during the second heating run was taken as the melting point temperature.

[0051] Reference Example 1 (Production of Polyamide 10T Salt Powder) 183.68 kg of terephthalic acid powder with an average particle size of 80 μm and 0.76 kg of sodium hypophosphite monohydrate as a polymerization catalyst were fed into a ribbon blender type reactor (capacity 600 L) and heated to 170° C. under nitrogen sealing while stirring at a rotation speed of 35 rpm. Then, while maintaining the temperature at 170° C., 198.89 kg of decanediamine heated to 110° C. was added to the terephthalic acid powder continuously at a rate of 1.3 kg / min over about 2.5 hours using a liquid injection device. During this time, the reactant remained in a powder state. Then, 16.67 kg of stearic acid as a terminal blocking agent was added to obtain a polyamide salt. The average particle size was 100 μm.

[0052] Example 1 (Preparation process + solid-state polymerization process (initial polymerization stage, main polymerization stage, and finishing polymerization stage)) In this example, polyamide was produced using the polymer production apparatus shown in Figure 1. The details are as follows. ·Preparation process: In a ribbon blender type vessel (reaction vessel 2) of 50 L capacity equipped with a 2.45 GHz microwave generator 1 and a condenser 3, 30 kg of the polyamide salt of Reference Example 1 as a raw material and 600 g of water were charged under a nitrogen gas flow, and the reaction vessel was heated to 250°C while stirring at a rotation speed of 60 rpm by a stirrer 21. In detail, in the heating process, the charged water was discharged from the condenser 3 from the point when the reaction vessel temperature exceeded 100°C, and the discharge of all the charged water was confirmed by the amount recovered in the recovery tank 30 until the reaction vessel temperature reached 250°C. When the reaction vessel temperature reached 250°C, the powder / granule temperature was 220°C, and this point was determined as the reaction start time. During the reaction, the powder / granule temperature, the stirring power value, and the amount of condensed water discharged to the outside of the system were observed. The powder / granule temperature is the temperature (Ta) of the powder / granule raw material 10, and is the temperature measured by a contact thermometer T1 near the middle position of the ribbon blender type vessel. The powder / grain temperature is the temperature of the powder / grain 10 at a distance x1 (see FIG. 1) from the inner wall of the reaction vessel 2 of 0.15×r and a depth y1 (see FIG. 1) from the powder / grain surface of 30 mm, where r (mm) is the diameter of the reaction vessel 2. The powder / grain surface refers to the surface of the powder / grain in the reaction vessel 2 during stirring. The reaction vessel temperature refers to the temperature (Tb) of the inner wall of the reaction vessel 2, and was controlled by the temperature of the heat medium (oil) flowing in from the inlet 221 in the jacket-type heat medium-type temperature adjustment device 22 of the reaction vessel 2. The temperature of the heat medium (oil) was measured by a contact thermometer T2 arranged at the inlet 221 of the jacket-type temperature adjustment device 22.

[0053] ·Solid phase polymerization process: After the start of the reaction, the temperature of the reaction vessel was maintained at 250° C. for 2 hours while stirring at a rotation speed of 60 rpm, and the powder temperature reached 235° C. (initial polymerization stage). Two hours after the start of the reaction, it was confirmed that the reaction rate had reached 50% from the amount of discharged condensation water, and then, while maintaining the reaction vessel temperature at 250°C, microwaves were irradiated at an output of 1 kW from the microwave generator 1 (main polymerization stage). The powder temperature immediately before microwave irradiation was 235°C. In detail, immediately after microwave irradiation, the powder temperature rose and exceeded the reaction vessel temperature, and 3 hours after the start of the reaction (i.e., 1 hour after the start of microwave irradiation), the powder temperature reached 260°C, and thereafter, the reaction vessel temperature of 250°C and the powder temperature of 260°C were maintained for 0.5 hours. After confirming that the discharge of condensation water had stopped 3.5 hours after the start of the reaction (i.e., 1.5 hours after the start of microwave irradiation), the temperature of the reaction vessel was kept at 250°C, and the microwave output value was adjusted to 0.9-1.2kW to keep the powder temperature at 260°C. Microwave irradiation was continued until 6 hours after the start of the reaction, to obtain polyamide (finishing polymerization stage). The total microwave irradiation time was 4 hours. In the solid-state polymerization step, the powder was continuously stirred at a rotation speed of 60 rpm. The time during which the solid-state polymerization was carried out with a temperature gradient in which the polymerization temperature of the powder raw material 10 was higher than the inner wall temperature of the reaction vessel 2 was 3 hours or more. The polyamide obtained in this example had a melting point of 316° C., was homogeneously melted without any gels, and was suitable for melt processing such as molding.

[0054] Example 2 (Preparation process + solid-state polymerization process (main polymerization stage and finishing polymerization stage)) In this example, polyamide was also produced using the polymer production apparatus shown in Figure 1. The details are as follows. ·Preparation process: Into the ribbon blender type vessel (reaction vessel 2) identical to that of Example 1, 30 kg of the polyamide salt of Reference Example 1 as a raw material and 600 g of water were charged under a nitrogen gas flow, and the reaction vessel was heated to 220°C while stirring at a rotation speed of 60 rpm by the stirrer 21, and irradiated with microwaves of 2.0 to 2.7 kW. In detail, in the heating process, the water charged from the point when the reaction vessel temperature exceeded 100°C was discharged from the condenser 3, and the discharge of all the charged water was confirmed by the amount recovered in the recovery tank 30 until the reaction vessel temperature reached 220°C. Heating by microwaves was further continued, and the time when the powder temperature reached 220°C was defined as the reaction start time. The reaction vessel temperature at this time was 220°C. During the reaction, the powder temperature, the stirring power value, and the amount of condensed water discharged to the outside of the system were observed. The reaction vessel temperature and the powder temperature were the same as those of Example 1, respectively.

[0055] ·Solid phase polymerization process: Even after the reaction started, the powder temperature continued to rise and exceeded the temperature of the reaction vessel (main polymerization stage) by continuing stirring at 60 rpm, heating the reaction vessel to 220°C, and irradiating with microwaves. In detail, 3.5 hours after the start of the reaction, the powder temperature reached 245°C. After 3.5 hours from the start of the reaction, it was confirmed that the discharge of condensation water had stopped, and thereafter, the temperature of the reaction vessel was kept at 220°C, the microwave output value was adjusted to 2.5-2.7kW, and the powder temperature was kept at 245°C while continuing to irradiate with microwaves until 6 hours after the start of the reaction, to obtain polyamide (finishing polymerization stage). The total microwave irradiation time after the start of the reaction was 6 hours. In the solid-state polymerization step, the powder was continuously stirred at a rotation speed of 60 rpm. The time during which the solid-state polymerization was carried out with a temperature gradient in which the polymerization temperature of the powder / particle raw material 10 was higher than the inner wall temperature of the reaction vessel 2 was 6 hours. The polyamide obtained in this example had a melting point of 316° C., was homogeneously melted without any gels, and was suitable for melt processing such as molding.

[0056] Comparative Example 1 (without microwave irradiation) A polyamide was produced in the same manner as in Example 1, except that microwave irradiation was not performed. The details are as follows. ·Preparation process: In the same ribbon blender type vessel as in Example 1, 30 kg of the polyamide salt of Reference Example 1 as raw materials and 600 g of water were charged under a nitrogen gas flow, and the reaction vessel was heated to 250°C while stirring at a rotation speed of 60 rpm. In detail, in the heating process, the charged water was discharged when the reaction vessel temperature exceeded 100°C, and it was confirmed that all the charged water was discharged by the time the reaction vessel temperature reached 250°C. When the reaction vessel temperature reached 250°C, the powder temperature was 220°C, and this point was determined as the reaction start time. During the reaction, the powder temperature, the stirring power value, and the amount of condensed water discharged outside the system were observed.

[0057] ·Solid phase polymerization process: After the reaction started, stirring at 60 rpm and heating of the reaction vessel to 250° C. were continued (main polymerization stage). Specifically, the powder temperature was 235 to 240° C. for 4 hours after the reaction started. After confirming that the discharge of condensed water had stopped 4 hours after the start of the reaction, the temperature of the reaction vessel was kept at 250°C until 6 hours after the start of the reaction, during which solid-state polymerization was carried out to obtain polyamide (finishing polymerization stage). From 4 hours to 6 hours after the start of the reaction, the powder temperature was 235 to 240°C. In the solid-state polymerization step, the powder particles were continuously stirred at a rotation speed of 60 rpm. The time during which solid-state polymerization was performed with a temperature gradient in which the polymerization temperature of the powder particles was higher than the inner wall temperature of the reaction vessel 2 was 0 hours. The melting point of the polyamide obtained in this comparative example was 316°C. When the inner wall of the reaction vessel was observed after the polymerization was completed, it was found that the inner wall was covered with the deposited polymer.

[0058] evaluation In Examples 1 and 2 and Comparative Example 1, the terminal reaction rates for each hour from the start of the reaction and the amount of adhesion to the can wall after the end of polymerization are shown in Table 1.

[0059] [Table 1]

[0060] In Examples 1 and 2, the powdered raw material was heated by microwaves and solid-phase polymerized at a temperature higher than the temperature of the inner wall of the reaction vessel while maintaining the temperature of the inner wall of the reaction vessel lower than the polymerization temperature of the powdered raw material, so that the amount of the powdered raw material adhering to the inner wall of the reaction vessel was less than that of Comparative Example 1. In particular, in Example 2, the temperature of the inner wall of the reaction vessel was lower than that of Example 1, so that the amount of the powdered raw material adhering to the inner wall of the reaction vessel was less. In addition, comparing the terminal reaction rates of Examples 1 and 2 with those of Comparative Example 1, the terminal reaction rates 2 hours after the start of the reaction were 58%, 58%, and 52%, respectively, which was slightly lower in Comparative Example 1. However, the terminal reaction rates 3 hours after the start of the reaction were 80% in Comparative Example 1, which used the conventional method not using microwaves, and 98% and 97% in Examples 1 and 2, which used microwaves, respectively, demonstrating that the reaction rate was faster by using microwaves. [Industrial Applicability]

[0061] The production method and production apparatus of the present invention are useful for producing any type of polymer, particularly polymers that can be polymerized based on a condensation reaction.

Claims

1. A method for producing a polymer, comprising the steps of: heating a powdered or granular raw material with microwaves in a reaction vessel equipped with a microwave generator, while maintaining the temperature of the inner wall of the reaction vessel lower than the polymerization temperature of the powdered or granular raw material, and performing solid-state polymerization at a temperature higher than the temperature of the inner wall of the reaction vessel.

2. 2. The method of claim 1, wherein the polymer is a polyamide.

3. 3. The method for producing a polymer according to claim 2, wherein the polymer is a polyamide comprising a dicarboxylic acid and a diamine, and 50 to 100 mol % of the dicarboxylic acid is terephthalic acid.

4. The method for producing a polymer according to claim 1, characterized in that the solid-state polymerization is carried out while changing the microwave output and / or the temperature of the inner wall of the reaction vessel, while detecting at least one of the temperature of the powdered or granular raw material and the load on the agitator.

5. The method for producing a polymer according to claim 1, characterized in that in order to prevent runaway of the reaction system due to an excessive increase in condensation water of the powder or granular material, solid-state polymerization is carried out while changing the microwave output and / or the temperature of the inner wall of the reaction vessel, while detecting at least one of the temperature of the powder or granular raw material, the load on the agitator, and the amount of water discharged to the outside.

6. An apparatus for producing a polymer, comprising: The manufacturing apparatus has a reaction vessel equipped with a microwave generator, The manufacturing apparatus is characterized in that the manufacturing apparatus heats the powdered or granular raw material with microwaves and polymerizes it in a solid state at a temperature higher than the temperature of the inner wall of the reaction vessel while maintaining the temperature of the inner wall of the reaction vessel lower than the polymerization temperature of the powdered or granular raw material.

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