Continuous and rapid polymer devolatilization device and monomer recycling process

Abstract

The invention provides a continuous and rapid polymer devolatilization device which comprises a devolatilization tank used for devolatilizing a polymer; a feed port and a gas phase outlet are formed in the top of the devolatilization tank, a microwave guide inlet is formed in the side wall of the devolatilization tank, and a discharge port is formed in the bottom of the devolatilization tank; a feed distributor is arranged in an inner cavity of the devolatilization tank and is used for receiving feed supplied by the feed port; the microwave system is used for generating microwaves to heat the polymer in the devolatilization tank; the microwave system comprises a microwave generating device and a waveguide, and microwaves generated by the microwave generating device are guided into the devolatilization tank through the waveguide inlet via the waveguide; the gas-liquid separation tank is used for carrying out gas-liquid separation on gas-phase volatile components in the devolatilization tank, and an inlet of the gas-liquid separation tank is connected to a gas-phase outlet of the devolatilization tank; the cooling tower is used for cooling the gas phase separated by the gas-liquid separation tank, and an inlet of the cooling tower is connected with an outlet of the devolatilization tank. According to the devolatilization device, microwave heating is used as assistance, materials are heated uniformly, and the devolatilization efficiency is high.

Description

Technical Field

[0001] The invention relates to the technical field of polymer devolatilization, in particular to a polymer continuous and rapid devolatilization device and a monomer recycling process. Background Art

[0002] With the advancement of technology and the development of society, the demand for polymer products is increasing. In the production technology of polymers, a devolatilization system is often provided to remove the unreacted monomers, oligomers, solvents and other volatile components in the polymer to improve the purity and performance of the product.

[0003] Bio-based and renewable biodegradable materials have received widespread attention as petroleum resources are becoming increasingly depleted and environmental pollution is becoming increasingly serious. It has become a general trend for them to replace petroleum-based plastic products and enter the lives of modern people. Among them, polylactic acid products use lactic acid obtained from biological fermentation as the main raw material, which has a wide source and is renewable. In addition, polylactic acid products can be biodegraded and will not pollute the environment. Therefore, they are a green polymer material that can be widely used.

[0004] The main processes for producing polylactic acid include direct polymerization of lactic acid, ring-opening polymerization and solid-phase polymerization. Among them, the ring-opening polymerization of lactide is the most widely used in industrial applications and has the best effect. At present, the process of producing polylactic acid by ring-opening polymerization of lactide mainly includes four main links: polymerization, devolatilization, pelletizing and monomer recovery. Among them, the devolatilization and monomer recovery process are the key steps to improve the quality and yield of polylactic acid products. The high viscosity of polylactic acid products, the high freezing point, high boiling point and thermal sensitivity of lactide monomers make the devolatilization and monomer recovery process very difficult. Therefore, how to devolatilize lactide cleanly and recycle it is an important issue in the industrial production process of polylactic acid.

[0005] Patent CN203525331U discloses a small-volume strip-type preheating devolatilization device for polylactic acid with a flat-cover cone head. The material is easier to flow downward and is not easy to accumulate, which reduces the mass transfer resistance. However, it is difficult to completely remove the monomer by only relying on the first-stage devolatilization, and a second-stage devolatilization is often required, which results in a too long residence time for the devolatilization, and the material is kept in a high temperature state for a long time, affecting the product quality.

[0006] Patent CN110394966A discloses a devolatilizing screw and a devolatilizing extruder, in which the threads of the first threaded portion and the second threaded portion rotate in opposite directions, thereby extruding the material for conveying. The material is formed into a film, a line, a strip, etc. under the action of the threaded unit, the material channel and a porous discharge plate to achieve devolatilization. However, this method is prone to material storage, and the polymer is easily subjected to high shear loads, resulting in a decrease in the molecular weight of heat-sensitive polymers.

[0007] Patent CN115770540A discloses an anti-blocking devolatilization tank for polylactic acid production. A discharge screw rod is provided, and the discharge screw rod is driven by a third motor to rotate to convey the polylactic acid, which can effectively avoid discharge blockage of the polylactic acid. However, this method increases the shearing of the material and affects the product quality.

[0008] In the prior art, the devolatilization process of polylactic acid generally has problems such as uneven heating of the melt and long devolatilization residence time resulting in yellowing of the material; volatile components are difficult to remove from the viscous material in time, resulting in low devolatilization efficiency; low molecular weight polymers are entrained in the gas phase, resulting in easy blockage of the gas phase pipeline, difficulty in directly recycling the lactide monomer, and poor quality of polylactic acid products under high shear conditions.

[0009] Therefore, there is an urgent need for an improved technology to improve the efficiency of the devolatilization process of polylactic acid and reduce the carryover of oligomers in the devolatilization process to achieve efficient production of polylactic acid. Summary of the invention

[0010] In order to overcome the deficiencies in the prior art, the present invention provides a polymer continuous rapid devolatilization device and a monomer recycling process.

[0011] In order to achieve the purpose of the present invention, the present invention adopts the following technical solutions:

[0012] In a first aspect, the present invention provides a polymer continuous rapid devolatilization device, comprising:

[0013] A devolatilizer is used for devolatilizing a polymer; a feed inlet and a gas phase outlet are provided on the top of the devolatilizer, a microwave inlet is provided on the side wall of the devolatilizer, and a discharge port is provided on the bottom; a feed distributor is provided in the inner cavity of the devolatilizer, and the feed distributor is used to receive the feed supplied by the feed inlet;

[0014] A microwave system, used for generating microwaves to heat the polymer in the devolatilization tank; the microwave system comprises a microwave generator and a waveguide, the microwaves generated by the microwave generator are introduced into the inner cavity of the devolatilization tank through the waveguide and the microwave introduction port;

[0015] A gas-liquid separation tank, used for separating the gas-phase volatiles in the devolatilization tank into gas and liquid, wherein the inlet of the gas-liquid separation tank is connected to the gas-phase outlet of the devolatilization tank;

[0016] A cooling tower is used to cool the gas phase separated by the gas-liquid separation tank, and the inlet of the cooling tower is connected to the outlet of the gas-liquid separation tank.

[0017] In some specific embodiments, the devolatilization device further comprises a preheater, the inlet of the preheater is connected to the feed end of the polymer, and the outlet is connected to the feed port of the devolatilization tank; and the preheater is used to preheat the polymer entering the devolatilization device.

[0018] In some specific embodiments, the outlet at the bottom of the devolatilizer tank delivers the devolatilized polymer product to the pelletizing process via a melt pump. Specifically, two gas phase outlets are symmetrically arranged at the top of the devolatilizer tank.

[0019] In some specific embodiments, a plurality of microwave introduction ports are provided on the side wall of the devolatilization tank along the vertical direction.

[0020] In some specific embodiments, the feed distributor is in an inverted cone shape, and the top cross-sectional area of ​​the feed distributor is 40% to 60%, such as 45%, 50%, or 55%, of the cross-sectional area of ​​the devolatilizer. The feed distributor is provided with feed holes on the conical side wall, and the spacing between the feed holes is 3 to 10 times, such as 4 times, 9 times, and preferably 5 to 8 times, such as 6 times, or 7 times, of the hole diameter.

[0021] In some preferred embodiments, the diameter of the feed hole is 5-20 mm, for example, 10 mm, 15 mm; more preferably 5-10 mm, for example, 8 mm; the number of the feed holes is 50-300, for example, 80, 200, more preferably 100-150, for example, 110, 130.

[0022] In some specific embodiments, the devolatilization device further includes a cold trap and a vacuum unit; the cold hydrazine is connected to the gas phase outlet of the cooling tower, and the outlet of the cold hydrazine is connected to the inlet of the vacuum unit. The cold trap further cools the gas phase at the gas phase outlet to ensure that all monomers are condensed, and other non-condensable vapors and impurity gases are discharged after being washed with water.

[0023] The devolatilization device provided by the present invention also needs to be equipped with some conventional components as needed, for example, an equipment jacket for heat preservation, a temperature measuring element for detecting the devolatilization temperature, a vacuum unit for providing vacuum degree, a heat exchange medium circulation system, etc. The structure of the above components belongs to the prior art in the field and will not be repeated here.

[0024] In a second aspect, the present invention further provides a method for continuous and rapid devolatilization of a polymer, wherein the method uses the above-mentioned device for devolatilization, and comprises the following steps:

[0025] S1, adjusting the outlet temperature of the preheater to heat the polymer to be devolatilized, and sending the preheated polymer to the devolatilization tank;

[0026] S2. Adjust the frequency of the microwave generator to 2000-5000 MHZ and the power density to 0.5-10 W / kg to heat and devolatilize the polymer entering the devolatilization tank;

[0027] S3. The heated polymer is discharged from the bottom discharge port of the devolatilizer, and the gaseous volatiles formed by heating enter the gas-liquid separation tank for gas-liquid separation. The separated gaseous monomers are cooled and recycled to the polymerization reaction.

[0028] In some embodiments, the temperature of the preheated polymer is increased to make it superheated, and the material is dispersed through a feed distributor in a devolatilizer. Specifically, the outlet temperature of the preheater is 175-215°C, preferably 190-205°C.

[0029] In some embodiments of the devolatilization method, the conditions for the heating devolatilization treatment of the polymer in the devolatilization tank are: temperature of 175-215°C, preferably 190-205°C; pressure of 20-2000 PaA, preferably 20-300 PaA; retention time of 5-50 min, preferably 5-20 min. The temperature of the melt in the devolatilization tank is adjusted by controlling the power of the microwave generator, so that the melt can maintain superheat during the devolatilization process, and avoid the increase in viscosity caused by the temperature reduction during the process of reducing the falling strips, thereby improving the devolatilization effect and achieving single-stage rapid devolatilization.

[0030] The volatiles removed by the continuous rapid devolatilization and monomer recycling process for polymers provided by the present invention are mainly unreacted monomers, by-products and solvents in the polymers. For bulk polymerization, the volatiles removed are mainly monomers and oligomers. The volatile content in the polymer or polymer solution before devolatilization is 5%-40%. After the devolatilization treatment, the volatile content can be specifically reduced to below 2000ppm, preferably below 1000ppm, and the acid value of the recovered lactide is below 25ppm.

[0031] In some specific embodiments, the polymer is selected from one or more of polylactic acid, polycarbonate, nylon, polystyrene, polyethylene, polyolefin, and polyester; preferably polylactic acid.

[0032] The above technical solution has the following technical effects:

[0033] The devolatilization device of the present invention utilizes microwave heating as an auxiliary, the material is heated evenly during the devolatilization process, the superheated temperature can be maintained in the devolatilization tank, the volatile matter is more likely to overflow, the devolatilization efficiency is high, the process is short, and the problem of increased viscosity due to temperature reduction is avoided.

[0034] The monomer recycling process of the present invention pre-separates the entrained impurities through the gas phase monomer recovery process, effectively improving the purity of the recovered monomers, reducing the monomer recovery cost, and increasing the utilization rate of the monomers. For the devolatilization of polymers such as polylactic acid, the material has a short high temperature residence time, and the obtained polylactic acid product has good quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 : A specific structural schematic diagram of the polymer continuous rapid devolatilization device of the present invention;

[0036] Among them, 1. preheater, 2. feed inlet, 3. feed distributor, 4. devolatilization tank, 5. microwave inlet, 6. discharge port, 7. gas phase outlet, 8. microwave generator, 9. waveguide, 10. gas-liquid separation tank, 11. gas-liquid separation tank waste liquid outlet, 12. cooling tower, 13. circulation pump, 14. cooler, 15. cold hydrazine, 16. vacuum unit. DETAILED DESCRIPTION

[0037] In order to facilitate the understanding of the present invention, the present invention will be further described below in conjunction with examples. It should be understood that the following examples are only for a better understanding of the present invention and do not mean that the present invention is limited to the following examples.

[0038] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0039] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in the art can be used. The instruments used without specifying the manufacturer are all conventional products that can be purchased commercially.

[0040] Unless otherwise specified, the main test methods used in the embodiments and comparative examples of the present invention are all common equipment and methods in the art:

[0041] (1) Hue: Directly test with DC-P3 fully automatic colorimeter produced by Beijing Xingguang Colorimetric Instrument Co., Ltd. to measure Hunter L value (brightness), b value (yellow-blue hue) and YI value (yellowness index). The higher the L value, the greater the brightness; the higher the b value, the yellower the polyester chips; polylactic acid is tested after sheeting.

[0042] (2) Mechanical properties: The tensile strength was measured using an Instron 5960 universal testing machine in accordance with ASTM D638 at a tensile speed of 50 mm / min.

[0043] (3) Molecular weight and molecular weight distribution coefficient: The molecular weight was determined using a 1515-2414 gel permeation chromatograph (GPC) from Waters, USA, with chloroform as the mobile phase, an elution rate of 1 mL / min, a column temperature of 30°C, and polystyrene as the standard sample.

[0044] (4) Melt flow rate index (MFR): Determined in accordance with ISO1133, the test conditions are 190°C, 2.16 kg, and a melting time of 5 minutes. MFR gives the extrusion flow rate of the molten plastic composition through an extrusion die of specified length and diameter under specified conditions (temperature, load, piston position), and determines the mass in the extrusion plastometer barrel discharged within a specified time.

[0045] (5) Melting point Tm: The sample was tested using a Perkins Elmer Plyris 1 differential scanning calorimeter. The sample was first heated to 180°C at 20°C / min to eliminate the thermal history, then cooled to -30°C at 20°C / min, and then heated at 10°C / min to obtain the DSC curve of the sample.

[0046] (6) Viscosity: The intrinsic viscosity was measured using a PVS1 / 2+VRM4 viscosity tester from LAUDA, Germany, in accordance with the national standard GB / T1632.5-2008, with phenol-tetrachloroethane (1:1) as the solvent.

[0047] The specific structure of the devolatilization device used in the following examples is as follows Figure 1 As shown, the continuous and rapid devolatilization device for polymers provided by the present invention comprises a devolatilization tank 4, a microwave system (a microwave generator 8, a waveguide 9, a microwave introduction port 5), a gas-liquid separation tank 10, a cooling tower 12, a circulating pump 13, a cooler 14, a cold trap 15 and a vacuum unit 16. The devolatilization tank 4 is used to devolatilize the polymer; a feed port 2 and a gas phase outlet 7 are provided at the top of the devolatilization tank 4; in some specific embodiments, two gas phase outlets 7 can be symmetrically provided at the top of the devolatilization tank 4. A plurality of microwave introduction ports 5 are provided on the side wall of the tank body of the devolatilization tank 4 in the vertical direction, and a discharge port 6 is provided at the bottom of the devolatilization tank 4, from which the devolatilized polymer is discharged and sent to the pelletizing process. A feed distributor 3 is provided in the inner cavity of the devolatilization tank 4, which is used to receive the polymer feed to be devolatilized supplied by the feed port 2.

[0048] The devolatilization device of the present invention is further provided with a gas-liquid separation tank 10 above the devolatilization tank 4 , which is connected to the gas phase outlet 7 of the devolatilization tank 4 .

[0049] In some specific embodiments, the feed distributor 3 is in an inverted cone shape, and the top cross-sectional area of ​​the feed distributor 3 is 40% to 60% of the cross-sectional area of ​​the gas-liquid separation tank 10; the feed distributor 3 is provided with feed holes on the conical side wall, and the spacing between the feed holes is 3 to 10 times the hole diameter, preferably 5 to 8 times.

[0050] In some preferred embodiments, the diameter of the feed hole is 5 to 20 mm, more preferably 5 to 10 mm; the number of the feed holes is 50 to 300, more preferably 100 to 150.

[0051] The microwave system is used to generate microwaves to heat the polymer inside the devolatilization tank 7; the microwave system includes a microwave generator 8 and a waveguide 9, and the microwaves generated by the microwave generator 8 are introduced into the inner cavity of the devolatilization tank 7 from the microwave introduction port 5 through the waveguide 9. In some specific embodiments, the microwave introduction port 5 can be set at 1 / 3 to 2 / 3 of the height of the devolatilization tank 4 tank body.

[0052] The gas-liquid separation tank 10 is used to separate the gas-phase volatiles in the devolatilization tank 4 into gas and liquid. The inlet of the gas-liquid separation tank 10 is connected to the gas-phase outlet of the devolatilization tank 4 .

[0053] The cooling tower 12 is used to cool the gas phase separated by the gas-liquid separation tank 10, and the inlet of the cooling tower 12 is connected to the outlet of the gas-liquid separation tank 10. In some specific embodiments, a circulating pump 13 is provided at the bottom of the cooling tower 12, and a part of the discharge of the circulating pump 13 is returned to the reaction section, and the other part is cooled by the cooler 14 and circulated to the cooling tower 12 to cool the gas phase.

[0054] The devolatilization device of the present invention is further provided with a preheater 1 before the polymer enters the devolatilization tank 4 , the inlet of the preheater 1 is connected to the feed end of the polymer, and the outlet is connected to the feed port 2 of the devolatilization tank 4 .

[0055] The devolatilization device also includes a cold trap 15 and a vacuum unit 16; the cold trap 15 is connected to the gas phase outlet of the cooling tower 12, and the gas phase at the outlet is further cooled by the cold trap and then connected to the vacuum unit 16. A coil is arranged inside the cold trap 15 for passing the cooling medium.

[0056] Example 1

[0057] Use Figure 1 The devolatilization device shown in the figure is used for rapid devolatilization of polylactic acid monomers for recycling. The polylactic acid polymer material to be treated is prepared by polymerization of L-lactide with an optical purity of ≥95% under the action of stannous octoate and an initiator, wherein the lactide contains 5.5wt% of unreacted lactide monomer and has a weight average molecular weight of 15±0.5×10 4 .

[0058] The specific process steps are:

[0059] S1, adjust the outlet temperature of preheater 1 to 195°C, the pressure in devolatilizer 4 to 300PaA, and the temperature to 195°C,

[0060] S2. Adjust the frequency of the microwave generator 8 to 2450 MHZ, the power density to 4 W / kg, the operating temperature of the cooling tower 12 to 102° C., and the operating temperature of the cold trap 15 to 40° C.; heat the polymer to be devolatilized, and send the preheated polymer to the devolatilization tank 4; the polylactic acid material is transported to the devolatilization tank 4 through the preheater 1 at a flow rate of 200 kg / h, and the material is dispersed and falls into strips after passing through the feed distributor 3, and the residence time of the material in the devolatilization tank 4 is controlled to be 15 min.

[0061] The polylactic acid product obtained after devolatilization by the melt pump is discharged from the outlet of the devolatilization tank 4, and the gaseous lactide monomer obtained after heating enters the gas-liquid separation tank 10 through the gas phase outlet. The entrained liquid phase accumulates in the gas-liquid separation tank 10 and then exits the gas-liquid separation tank waste liquid outlet 11. The remaining gaseous monomer enters the cooling tower 12 for cooling, and the lactide obtained after cooling is transported to the reaction unit through the pump and mixed with the fresh feed to continue the reaction. The non-condensable steam passes through the cold trap 15 and enters the vacuum unit 16 for discharge.

[0062] The polymer devolatilization and monomer recycling device was continuously operated for 3h, 20h, 50h, and 200h before sampling. The polylactic acid product finally obtained was analyzed and measured. The results are shown in Table 1:

[0063] Table 1

[0064]

[0065] The recovered lactide monomer product was analyzed and measured, and the results are shown in Table 2:

[0066] Table 2

[0067]

[0068] Example 2

[0069] Use Figure 1 The devolatilization device shown in the figure is used for rapid devolatilization of polylactic acid monomers for recycling. The polylactic acid polymer material to be treated is prepared by polymerization of L-lactide with an optical purity of ≥95% under the action of stannous octoate and an initiator, wherein the lactide monomer contains 5.3 wt% of unreacted lactide and has a weight average molecular weight of 1.7*10 5 .

[0070] The specific process steps are:

[0071] S1, adjust the outlet temperature of preheater 1 to 200°C, the pressure in devolatilizer 4 to 200PaA, and the temperature to 200°C;

[0072] S2. Adjust the frequency of the microwave generator 8 to 2450 MHZ, the power density to 5 W / kg, the operating temperature of the cooling tower 12 to 102° C., and the operating temperature of the cold trap 15 to 40° C.; heat the polymer to be devolatilized, and send the preheated polymer to the devolatilization tank 4; the polylactic acid material is transported to the devolatilization tank 4 through the preheater 1 at a flow rate of 150 kg / h, and the material is dispersed and falls into strips after passing through the feed distributor 3, and the residence time of the material in the devolatilization tank 4 is controlled to be 20 min.

[0073] The polylactic acid product obtained after devolatilization by the melt pump is discharged from the outlet of the devolatilization tank 4, and the gaseous lactide monomer obtained after heating enters the gas-liquid separation tank 10 through the gas phase outlet. The entrained liquid phase accumulates in the gas-liquid separation tank 10 and then exits the gas-liquid separation tank waste liquid outlet 11. The remaining gaseous monomer enters the cooling tower 12 for cooling, and the lactide obtained after cooling is transported to the reaction unit through the pump and mixed with the fresh feed to continue the reaction. The non-condensable steam passes through the cold trap 15 and enters the vacuum unit 16 for discharge.

[0074] The polymer devolatilization and monomer recycling device was continuously operated for 3h, 20h, 50h, and 200h before sampling. The final polylactic acid product was analyzed and measured. The results are shown in Table 3:

[0075] Table 3

[0076]

[0077]

[0078] The recovered lactide monomer product was analyzed and measured, and the results are shown in Table 4:

[0079] Table 4

[0080] Sampling time Free acid content Guangchun h mmol / kg ％ 3 20 99.6 20 18 99.6 50 17 99.4 200 19 99.5

[0081] Comparative Example 1

[0082] The difference between this comparative example and Example 1 is that the microwave system is not activated. The system is operated continuously for 3 hours, and samples are taken after 20 hours. The results are shown in Table 5;

[0083] Table 5

[0084]

[0085] The recovered lactide monomer product was analyzed and measured, and the results are shown in Table 6:

[0086] Table 6

[0087] Sampling time Free acid content Guangchun h mmol / kg ％ 3 22 99.5 20 20 99.5

[0088] From the output and product quality data of the above examples, it can be seen that the devolatilization device of the present invention uses microwave heating as an auxiliary, the material is heated evenly during the devolatilization process, the overheating temperature can be maintained in the devolatilization tank, the volatile matter is more likely to overflow, and the devolatilization efficiency is high. After the monomer recycling process of the present invention undergoes primary devolatilization, the residual monomer content of the polymer can still be maintained below 1000ppn after the operation time exceeds 200h, the quality of the obtained polymer product is good, and the acid value of the recovered monomer can be maintained at 20mmol / kg, the optical purity is above 99.6%, which meets the monomer recovery standard, and can be recycled to the reaction unit to continue to participate in the reaction, thereby improving the utilization rate of the monomer.

Claims

1. A polymer continuous rapid devolatilization device, characterized in that: include: A devolatilizer is used for devolatilizing a polymer; a feed inlet and a gas phase outlet are provided on the top of the devolatilizer, a microwave inlet is provided on the side wall of the devolatilizer, and a discharge port is provided on the bottom; a feed distributor is provided in the inner cavity of the devolatilizer, and the feed distributor is used to receive the feed supplied by the feed inlet; A microwave system, used for generating microwaves to heat the polymer in the devolatilization tank; the microwave system comprises a microwave generator and a waveguide, the microwaves generated by the microwave generator are introduced into the inner cavity of the devolatilization tank through the waveguide and the microwave introduction port; A gas-liquid separation tank, used for separating the gas-phase volatiles in the devolatilization tank into gas and liquid, wherein the inlet of the gas-liquid separation tank is connected to the gas-phase outlet of the devolatilization tank; A cooling tower is used to cool the gas phase separated by the gas-liquid separation tank, and the inlet of the cooling tower is connected to the outlet of the gas-liquid separation tank.

2. The polymer continuous rapid devolatilization device according to claim 1, characterized in that: The devolatilization device further comprises a preheater; the inlet of the preheater is connected to the feed end of the polymer, and the outlet is connected to the feed port of the devolatilization tank.

3. The polymer continuous rapid devolatilization device according to claim 1 or 2, characterized in that: A plurality of microwave introduction ports are vertically arranged on the side wall of the devolatilization tank.

4. The polymer continuous rapid devolatilization device according to claim 3, characterized in that: The feed distributor is in an inverted cone shape, and the top cross-sectional area of ​​the feed distributor is 40% to 60% of the cross-sectional area of ​​the devolatilizer; The feed distributor is provided with feed holes on the conical side wall, and the spacing between the feed holes is 3 to 10 times, preferably 5 to 8 times, of the hole diameter.

5. The polymer continuous rapid devolatilization device according to claim 4, characterized in that: The diameter of the feed holes is 5 to 20 mm, more preferably 5 to 10 mm; the number of the feed holes is 50 to 300, more preferably 100 to 150.

6. The polymer continuous rapid devolatilization device according to claim 5, characterized in that: The devolatilization device also includes a cold trap and a vacuum unit; The cold hydrazine is connected to the gas phase outlet of the cooling tower, and the outlet of the cold hydrazine is connected to the inlet of the vacuum unit.

7. A process for continuous and rapid devolatilization of polymers and monomer recycling, characterized in that: The method adopts the device described in any one of claims 1 to 6 to carry out devolatilization, comprising the following steps: S1, adjusting the outlet temperature of the preheater to heat the polymer to be devolatilized, and sending the preheated polymer to the devolatilization tank; S2. Adjust the frequency of the microwave generator to 2000-5000 MHZ and the power density to 0.5-10 W / kg to heat and devolatilize the polymer entering the devolatilization tank; S3. The heated polymer is discharged from the bottom discharge port of the devolatilizer, and the gaseous volatiles formed by heating enter the gas-liquid separation tank for gas-liquid separation. The separated gaseous monomers are cooled and recycled to the polymerization reaction.

8. The devolatilization and monomer recycling process according to claim 7, characterized in that: The outlet temperature of the preheater in S1 is 175-215°C, preferably 190-205°C; The conditions for the heating devolatilization treatment of the polymer in S2 in the devolatilization tank are: temperature of 175-215°C, preferably 190-205°C; pressure of 20-2000 PaA, preferably 20-300 PaA; retention time of 5-50 min, preferably 5-20 min.

9. The devolatilization and monomer recycling process according to claim 7 or 8, characterized in that: The monomer content in the polymer discharged from the discharge port in S3 is below 2000 ppm, preferably below 1000 ppm.

10. The devolatilization and monomer recycling process according to any one of claims 7 to 9, characterized in that: The polymer is selected from one or more of polylactic acid, polycarbonate, nylon, polystyrene, polyethylene, polyolefin, and polyester; preferably polylactic acid.

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