Device for depolymerizing polycaprolactone into epsilon-caprolactone monomer

Abstract

The utility model discloses a device for depolymerizing polycaprolactone into epsilon-caprolactone monomers, which relates to the field of polyester material depolymerization and comprises a kettle body, an oil heating jacket, a discharge port, a kettle cover, a material port, a condenser, a vacuumizing port, a collecting tank and a stirring paddle. A heat insulation layer is arranged between the kettle cover and the kettle body, holes penetrating up and down are distributed in the heat insulation layer, and a first water inlet and a first water outlet are respectively formed in the outer side of the heat insulation layer; a material opening, a second water inlet and a second water outlet are formed in the kettle cover; the kettle cover is provided with a pipeline communicated with the condenser; the condenser is respectively connected with the vacuumizing opening and the collecting tank; the stirring paddle is connected with the inner wall of the kettle cover and penetrates through the heat-insulating layer to extend into the kettle body; the lower part of the kettle body is connected with a discharge port; the outer side of the kettle body is connected with an oil heating sleeve. Through the design of the heat insulation layer, the production of byproducts is effectively reduced, and the depolymerization efficiency, the product yield and the purity are improved; by designing the unique stirring paddle, the efficient mixing of PCL and the catalyst is realized, and the catalytic depolymerization efficiency is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of polyester material depolymerization, and specifically relates to a device for depolymerizing polycaprolactone into epsilon-caprolactone monomer BACKGROUND

[0002] Polycaprolactone PCL is widely used in tissue engineering and medical fields due to its good biocompatibility and biodegradability. In recent years, the demand for polycaprolactone has gradually increased. However, in the process of preparing epsilon-caprolactone, high temperature can cause part of the monomer to undergo ring-opening polymerization to form polycaprolactone. The disposal of this part of polycaprolactone not only greatly increases the production cost of epsilon-caprolactone, but also causes resource waste. At the same time, the epsilon-caprolactone on the market in China mainly depends on imports, and its high price limits the large-scale application of polycaprolactone. If the waste polycaprolactone after consumption can be recycled and depolymerized into epsilon-caprolactone monomer raw material, the high-value utilization of polycaprolactone can be realized.

[0003] Unfortunately, the research on the depolymerization of polycaprolactone currently only stays in the depolymerization method and process, and the depolymerization device used is an ordinary flask or a reaction kettle. There is no special device for depolymerization. The ordinary flask or reaction kettle cannot accurately control the temperature of the evaporated material, which causes a large temperature span of the evaporated material. However, high temperature can cause epsilon-caprolactone to react again to form dimers, trimers and other oligomers in the evaporation path. This not only causes the deposition of dimers, trimers and other oligomers in the pipeline, but also significantly affects the purity of the target product epsilon-caprolactone. This is the reason why there are many documents that epsilon-caprolactone contains dimers, trimers and other by-products. UTILITY MODEL CONTENTS

[0004] Therefore, the utility model aims at providing a device for depolymerizing polycaprolactone into epsilon-caprolactone monomer to solve the technical problem.

[0005] To achieve the above-mentioned purpose, the utility model provides the following technical scheme.

[0006] A device for depolymerizing polycaprolactone into epsilon-caprolactone monomer, comprising a kettle body, an oil heating jacket, a discharge port, a kettle cover, a feed port, a condenser, a vacuum port, a collection tank and a stirring paddle. A heat insulation layer is arranged between the kettle cover and the kettle body. The heat insulation layer is provided with holes penetrating from top to bottom, and the outer side of the heat insulation layer is provided with a first water inlet and a first water outlet. The kettle cover is provided with a feed port, a second water inlet and a second water outlet. The kettle cover is provided with a pipeline connected to the condenser. The condenser is connected to the vacuum port and the collection tank. The stirring paddle is connected to the inner wall of the kettle cover and penetrates the heat insulation layer to extend into the kettle body. The lower part of the kettle body is connected to the discharge port. The outer side of the kettle body is connected to the oil heating jacket.

[0007] Further, the number of the material openings is one or more; for example, two, including a large material opening and a small material opening.

[0008] Further, the kettle cover is an inner hollow structure, and the cavity is in communication with the second water inlet and the second water outlet; temperature control is achieved by injecting cooling medium into the cavity.

[0009] Or further, the inner wall of the kettle cover is provided with a condensing pipeline, and the condensing pipeline is in communication with the second water inlet and the second water outlet; temperature control is achieved by injecting cooling medium into the condensing pipeline.

[0010] Further, the heat insulation layer is an inner hollow structure, and the cavity is in communication with the first water inlet and the first water outlet; temperature control is achieved by injecting cooling medium into the cavity.

[0011] Or further, the heat insulation layer is provided with a condensing pipeline, and the condensing pipeline is in communication with the first water inlet and the first water outlet; temperature control is achieved by injecting cooling medium into the condensing pipeline.

[0012] By adopting the above technical scheme, the worker pours the weighed polycaprolactone and catalyst and other materials into the kettle body, and seals the device; then the worker draws vacuum through the vacuum port to reduce the pressure in the reaction kettle to a specified value, and at the same time, the worker can adjust the pressure to 10 Pa-101 kPa through the high-precision vacuum regulating valve; then the worker provides dimethyl silicone oil and other heating media into the oil heating jacket through the circulating oil bath machine as circulating hot oil to heat the kettle body to a specified temperature; continue to increase the temperature of the reaction kettle to the polycaprolactone depolymerization temperature; the circulating refrigerator respectively passes cooling liquid into the heat insulation layer and the kettle cover through the first water inlet, the first water outlet, the second water inlet and the second water outlet, and respectively passes cooling liquid into the heat preservation sleeve and the condenser, and accurately controls the temperature at the kettle cover, the heat insulation layer, the heat preservation sleeve and the condenser, for example, when the cooling liquid temperature is adjusted to make the heat insulation layer temperature 60-80℃ and the kettle cover temperature 50-70℃, the product ε-caprolactone enters the kettle cover from the kettle body through the hole provided in the heat insulation layer, and the temperature after passing through the heat insulation layer is controlled at 60-80℃, further, the product gas is further controlled at 50-70℃ before entering the condenser from the kettle cover through the pipeline, at this temperature, the ε-caprolactone will not condense back to the kettle body, nor will it rapidly polymerize to generate oligomer byproducts such as dimers and trimers due to the high internal temperature of the gas, thereby significantly improving the monomer yield and purity of ε-caprolactone.

[0013] Further, the diameter of the hole in the heat insulation layer can be 10mm-50mm±5mm, preferably 10mm-20mm±5mm. The number of holes can be more than 100. A large number of small-diameter holes can increase the contact time of the product gas with the heat insulation layer, achieving better temperature control effect.

[0014] Further, the condenser is connected with a molecular sieve, and is further connected with a vacuum extraction port and a collection tank.

[0015] Further, the condenser is combined with a spherical condenser and a serpentine condenser, so that the longer cooling path is ensured, and the byproduct is prevented from being blocked in the serpentine condenser; the molecular sieve connected with the tail of the condenser can effectively adsorb the byproduct; the stirring paddle is opened, the stirring paddle is a turbine stirring paddle, which can generate strong up-down circulating flow in the kettle to realize efficient mixing of PCL and catalyst, increase the reaction interface, improve the efficiency of catalytic depolymerization, bring stronger shear force and mixing efficiency, and stop the reaction after a specified time.

[0016] Further, the oil heating jacket uses dimethyl silicone oil as a heating medium, and a circulating oil bath machine is used to provide circulating hot oil to control the temperature in the kettle.

[0017] Further, the diameter of the waist of the kettle body is the largest, and gradually narrows towards the upper and lower sides of the waist.

[0018] Further, the capacity of the kettle body can be 80-100L, the diameters of the upper opening and the lower opening are 25-40cm, the diameter of the inner cavity of the kettle body is 50-100cm, and the height of the inner cavity is 50-120cm.

[0019] By adopting the above technical solution, the sealing area can be reduced, the sealing performance of the device can be improved, and 50kg of polycaprolactone can be depolymerized in a single reaction.

[0020] Further, the stirring paddle is driven by an external motor. Further, a magnetic coupler can be used to connect the stirring paddle and the motor transmission. By adopting the above technical solution, since the torque is transmitted without contact, the static seal is replaced by the dynamic seal, and the sealing performance of the device can be improved.

[0021] Further, the same or different double sealing rings of silicone rubber and polytetrafluoroethylene are respectively used between the kettle cover and the heat insulation layer, and between the heat insulation layer and the kettle body.

[0022] Further, the kettle body, the kettle cover, and the stirring paddle are preferably made of 316L, and the inner wall of the kettle body and the kettle cover, the outer lining of the stirring paddle, and the heat insulation layer are preferably made of polytetrafluoroethylene.

[0023] By adopting the above technical solution, the sealing performance is excellent, and both polytetrafluoroethylene and 316L stainless steel have good corrosion resistance and surface lubricity, which can prolong the service life and reduce wear.

[0024] Further, mechanical seals are used for the pipeline connection parts of the large material port, the small material port, and the vacuum extraction port, and a discharge ball valve is installed on the discharge port.

[0025] By adopting the technical scheme, the mechanical seal is arranged, and air leakage at pipeline connection positions such as the large material port, the small material port and the vacuum extraction port is effectively avoided.

[0026] Further, a pipeline in communication with the condenser is wrapped by a heat preservation sleeve.

[0027] Further, the heat preservation sleeve is provided with a thermocouple and circulating liquid, and the circulating liquid medium can be selected from at least one of a salt water solution, ethanol, ethylene glycol and glycerol.

[0028] By adopting the technical scheme, the ε-caprolactone is preserved by the heat preservation sleeve, and is neither condensed back to the reaction kettle nor generates byproducts such as oligomers. Specifically, the temperature can be controlled at 50-70℃.

[0029] Further, the vacuum extraction port is connected with a high-precision vacuum regulating valve on one side, and the regulating range is 10 Pa-101 kPa.

[0030] By adopting the technical scheme, the worker reduces the pressure in the reaction kettle to a specified value through the vacuum extraction port, and adjusts the pressure to 10 Pa-101 kPa through the high-precision vacuum regulating valve.

[0031] Further, the kettle cover and the heat insulation layer each have a circulating refrigerator providing circulating cooling liquid, the circulating refrigerator adjusts the refrigeration temperature by measuring the temperature of water outlet at the first water outlet and the second water outlet, the cooling medium can be selected from at least one of a salt water solution, ethanol, ethylene glycol and glycerol, the temperature of the heat insulation layer is preferably set to 70℃, and the temperature of the kettle cover is preferably set to 60℃.

[0032] By adopting the technical scheme, the temperatures at the kettle cover, the heat insulation layer, the heat preservation sleeve and the condenser are accurately controlled. For example, when the cooling liquid temperature is adjusted to make the temperature of the heat insulation layer 70℃ and the temperature of the kettle cover 60℃, the temperature of the product ε-caprolactone after passing through the heat insulation layer is controlled at 50-70℃, at which the ε-caprolactone neither condenses back to the reaction kettle nor generates byproducts such as oligomers, and the depolymerization efficiency of the ε-caprolactone can be significantly improved.

[0033] Further, the condenser is composed of a spherical condenser and a serpentine condenser, the cooling medium is selected from at least one of a salt water solution, ethanol, ethylene glycol and glycerol, the cooling temperature is preferably set to -20-35℃, and is further preferably set to -5-5℃; the effective length of the spherical condenser is 40-80 cm, the length-diameter ratio is 6:1, and the minimum diameter of the internal pipe is 2-3 cm; the length of the outer sleeve of the serpentine condenser is 40-80 cm, the length-diameter ratio is 5:1-15:1, and the diameter of the internal pipeline is 2-3 cm.

[0034] By adopting the above technical solution, which combines spherical and serpentine condensers, a longer cooling path can be ensured while avoiding blockage of by-products in the serpentine condenser.

[0035] Furthermore, the impeller is a turbine impeller, specifically one of a flat turbine impeller, a disc turbine impeller, or a folding blade turbine impeller, with an impeller rotation speed of 50-500 rpm.

[0036] By adopting the above technical solution, a strong up-and-down circulating flow can be generated in the reactor, resulting in stronger shear force and mixing efficiency, thereby increasing the contact area between polycaprolactone and the catalyst, and improving the depolymerization efficiency and degree.

[0037] In summary, the present invention has the following main advantages:

[0038] 1. This invention achieves efficient mixing of PCL and catalyst through a uniquely designed stirring impeller, increasing the reaction interface and improving the efficiency of catalytic depolymerization. The stirring impeller is a turbine impeller, which can generate strong vertical circulation within the reactor, resulting in stronger shear force and mixing efficiency;

[0039] 2. This utility model utilizes a unique vacuum control system and cooling system. The device provides detailed specifications for the vessel shape, insulation layer structure, stirring paddle sealing method, gasket material, and sealing methods at pipe connections, exhibiting excellent sealing performance. It precisely controls the temperatures of the vessel lid, insulation layer, insulation jacket, and condenser. For example, when the coolant temperature is adjusted to 70°C for the insulation layer and 60°C for the vessel lid, the temperature of the ε-caprolactone product after passing through the insulation layer will be controlled at 60-70°C. At this temperature, ε-caprolactone will neither condense and flow back into the reactor nor generate oligomers or other byproducts, significantly improving the depolymerization efficiency of ε-caprolactone. The combination of a spherical condenser and a serpentine condenser ensures a long cooling path while preventing byproduct blockage in the serpentine condenser.

[0040] 3. This invention yields high-purity and high-conversion-rate ε-caprolactone depolymerization products. During the by-product generation stage, the cooling system of the vessel lid and insulation layer reduces by-product formation; during the by-product removal stage, the molecular sieve connected to the condenser tail effectively adsorbs by-products. Both of these aspects significantly improve the purity of the ε-caprolactone product. The final depolymerization product has a liquid yield of over 96%, and the ε-caprolactone is highly pure with virtually no impurities. The conversion rate of polycaprolactone is also over 90%. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the structure of this utility model;

[0042] Figure 2This is a schematic diagram of the oil heating jacket structure of this utility model;

[0043] Figure 3 This is a schematic diagram of the lid structure of the present invention;

[0044] Figure 4 This is a bottom view of the vessel body structure of this utility model;

[0045] Figure 5 This is a top-section structural diagram of the heat insulation layer according to Embodiment 1 of this utility model;

[0046] Figure 6 This is a top-section structural diagram of the heat insulation layer in Embodiment 2 of this utility model.

[0047] In the diagram: 1. Reactor body; 2. Oil heating jacket; 3. Discharge port; 4. Insulation layer; 41. First water inlet; 42. First water outlet; 5. Reactor lid; 6. Second water inlet; 7. Material outlet; 8. Discharge ball valve; 9. Second water outlet; 10. Insulation jacket; 11. Condenser; 1101. Spherical condenser; 1102. Serpentine condenser; 12. Molecular sieve; 13. Vacuum port; 14. Collection tank; 15. Pipeline; 16. Stirring paddle; 17. High-precision vacuum regulating valve. Detailed Implementation

[0048] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0049] The embodiments of this utility model will be described below based on its overall structure.

[0050] Example 1:

[0051] An apparatus for depolymerizing polycaprolactone into ε-caprolactone monomers, such as... Figures 1-5 As shown, it includes a vessel body 1, an oil heating jacket 2, a discharge port 3, a vessel lid 5, a material port 7, a condenser 11, a vacuum port 13, a collection tank 14, and a stirring paddle 16.

[0052] The heat insulation layer 4 is provided between the kettle cover 5 and the kettle body 1, and is provided with holes penetrating from top to bottom, and the product gas passes through the holes from the kettle body 1 into the kettle cover 5; the outer side of the heat insulation layer 4 is provided with a first water inlet 41 and a first water outlet 42, so as to realize temperature control by inputting and outputting cooling liquid; the heat insulation layer 4 is of an inner hollow structure, and the cavity is communicated with the first water inlet 41 and the first water outlet 42, so as to realize temperature control by injecting cooling medium into the cavity; the kettle cover 5 is provided with a material port 7, a second water inlet 6 and a second water outlet 9, and the inner wall of the kettle cover 5 is provided with a condensing pipeline, which realizes temperature control by being communicated with the second water inlet 6 and the second water outlet 9; the kettle cover 5 is provided with a pipeline 15 communicated with a condenser 11, the pipeline 15 is wrapped by a heat preservation sleeve 10, the heat preservation sleeve 10 is provided with a thermocouple and circulating liquid, the circulating liquid medium is selected from at least one of brine solution, ethanol, ethylene glycol and glycerol, and the pipeline temperature is controlled by adjusting the circulating liquid temperature; the condenser 11 is connected with a molecular sieve 12, a vacuumizing port 13 and a collecting tank 14, the vacuumizing port 13 is connected with a high-precision vacuum regulating valve 17 on one side, and the regulating range is 10 Pa-101 kPa; a stirring paddle 16 is connected with the inner wall of the kettle cover 5 and penetrates through the heat insulation layer 4 to extend into the kettle body 1, the stirring paddle 16 is driven by an external motor, and a magnetic coupler is used to connect the stirring paddle 16 and the motor transmission, so that the torque is transmitted without contact, the dynamic seal is replaced by the static seal, the sealing property of the device is improved, the stirring paddle 16 is a turbine stirring paddle, specifically one of a flat turbine stirring paddle, a butterfly turbine stirring paddle or a folding turbine stirring paddle, the rotating speed of the stirring paddle 16 is 50-500 rpm, a strong up-down circulating flow can be generated in the kettle, stronger shearing force and mixing efficiency are brought, the contact area between the polycaprolactone and the catalyst is increased, and the depolymerization efficiency and the depolymerization degree are improved; the lower part of the kettle body 1 is connected with the discharge port 3; the outer side of the kettle body 1 is connected with an oil heating sleeve 2, the oil heating sleeve 2 uses dimethyl silicone oil as heating medium, and the circulating hot oil is provided by a circulating oil bath machine to control the temperature in the kettle.

[0053] Referring to Figures 1-4In the above embodiment, the kettle body 1 has the largest diameter at the waist, and gradually narrows upwards and downwards from the waist, so as to reduce the sealing area and improve the sealing performance of the device; the kettle body 1 has a capacity of about 80-100L, the upper opening and the lower opening have a diameter of 25-40cm, the inner cavity of the kettle body 1 has a diameter of 50-100cm, and the inner cavity height is 50-120cm, so that 50kg of polycaprolactone can be depolymerized in a single reaction. The diameter of the holes in the heat insulation layer is 10mm-50mm±5mm, and is preferably 10mm-20mm±5mm, and the number of holes is more than 100. The silicon rubber and polytetrafluoroethylene double sealing ring is selected between the kettle cover 5 and the heat insulation layer 4, and between the heat insulation layer 4 and the kettle body 1, so as to improve the sealing performance of the device; the kettle body 1, the kettle cover 5 and the stirring paddle 16 are made of 316L, and the metal surface roughness is 0.16-0.32um; the inner wall of the kettle body 1 and the kettle cover 5, the outer lining of the stirring paddle 16 and the heat insulation layer 4 are made of polytetrafluoroethylene; the mechanical seal is selected for the pipeline connection parts such as the material port 7 and the vacuum extraction port 13, so as to improve the sealing performance of the device through the interaction between the rotating part and the stationary part; and the discharge port 3 is provided with a discharge ball valve 8.

[0054] Referring to Figures 1-4 In the above embodiment, the kettle cover 5 and the heat insulation layer 4 each have a circulating refrigeration machine to provide circulating cooling liquid, the circulating refrigeration machine adjusts the refrigeration temperature by measuring the temperature of the second water outlet 9 and the first water outlet 42, and the cooling medium is selected from at least one of a salt water solution, ethanol, ethylene glycol and glycerol, so as to accurately control the temperature of the product ε-caprolactone gas flow; the temperature of the heat insulation layer 4 is preferably set to 70℃, and the temperature of the kettle cover 5 is preferably set to 60℃; the condenser 11 is composed of a spherical condenser 1101 and a serpentine condenser 1102, the cooling medium is selected from at least one of a salt water solution, ethanol, ethylene glycol and glycerol, and the cooling temperature is-20-35℃; the effective length of the spherical condenser 1101 is 40-80cm, the length-diameter ratio is 6:1, and the minimum diameter of the internal tube is 2-3cm; the length of the outer sleeve of the serpentine condenser 1102 is 40-80cm, the length-diameter ratio is 5:1-15:1, and the diameter of the internal pipeline is 2-3cm.

[0055] Embodiment two:

[0056] On the basis of the above embodiment one, the internal shape of the kettle cover 5 is changed to realize another temperature control mode.

[0057] In the above embodiment, the kettle cover 5 has an inner hollow structure, and the cavity realizes temperature control through communication with the second water inlet 6 and the second water outlet 9.

[0058] Embodiment three:

[0059] On the basis of the above embodiment one, the internal shape of the heat insulation layer 4 is changed to realize another temperature control mode.

[0060] Referring to Figure 6In the above embodiment, the heat insulation layer 4 is internally provided with a condensing pipeline, and the condensing pipeline realizes temperature control by being communicated with the first water inlet 41 and the first water outlet 42.

[0061] Embodiment four:

[0062] On the basis of the above-mentioned embodiment three, the internal shape of the kettle cover 5 is changed to realize another temperature control mode.

[0063] In the above embodiment, the kettle cover 5 is an inner hollow structure, and the cavity realizes temperature control by being communicated with the second water inlet 6 and the second water outlet 9.

[0064] The implementation principle of the utility model is as follows: firstly, the staff adds the weighed polycaprolactone and catalyst and other materials into the kettle body 1, and seals the device; then the staff draws vacuum through the vacuum port 13 to reduce the pressure in the reaction kettle to a specified value, and the staff adjusts the pressure to 10Pa-101kPa through the high-precision vacuum regulating valve 17; then the staff provides dimethyl silicone oil as circulating hot oil into the oil heating jacket 2 through the circulating oil bath to heat the kettle body 1 to a specified temperature; continue to raise the temperature of the reaction kettle to the polycaprolactone depolymerization temperature; the circulating refrigerator passes cooling liquid into the kettle cover 5 and the heat insulation layer 4 through the second water inlet 6 and the first water inlet 41, and passes cooling liquid into the heat preservation sleeve 10 and the condenser 11 respectively, and accurately controls the temperature at the kettle cover 5, the heat insulation layer 4, the heat preservation sleeve 10 and the condenser 11, for example, when the cooling liquid temperature is adjusted to make the temperature of the heat insulation layer 4 70 DEG C and the temperature of the kettle cover 5 60 DEG C, the temperature of the product epsilon-caprolactone after passing through the heat insulation layer 4 will be controlled at 60-70 DEG C, and at this temperature, the epsilon-caprolactone will neither condense backflow to the reaction kettle nor generate by-products such as oligomers, and the depolymerization efficiency of the epsilon-caprolactone can be significantly improved; and the spherical condenser 1101 and the serpentine condenser 1102 are combined to ensure a long cooling path while avoiding the blocking of by-products in the serpentine condenser 1102; and the molecular sieve 12 connected to the tail of the condenser 11 can effectively adsorb by-products; the stirring paddle 16 is opened, the stirring paddle 16 is a turbine stirring paddle, can generate strong up and down circulating flow in the kettle, realize efficient mixing of PCL and catalyst, increase the reaction interface, improve the efficiency of catalytic depolymerization, bring stronger shear force and mixing efficiency, and stop the reaction after a specified time.

[0065] The above embodiment is the preferred implementation mode of the utility model, but the implementation mode of the utility model is not limited by the above embodiment, any person skilled in the art can think of changes, modifications, substitutions, combinations and simplifications without departing from the spirit and principle of the utility model, which should be equivalent replacement mode and should be covered in the protection scope of the utility model.

[0066] Although the embodiments of the utility model have been shown and described, the specific embodiments are only the explanation of the utility model, and are not the limitation of the utility model, and the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable way, and the person skilled in the art can make the modification, replacement and change of the embodiments without the creative contribution after reading the specification without departing from the principles and the purpose of the utility model, but as long as in the claim range of the utility model, it is protected by the patent law.

Claims

1. An apparatus for depolymerizing polycaprolactone into ε-caprolactone monomers, comprising a vessel body (1), an oil heating jacket (2), a discharge port (3), a vessel lid (5), a feed port (7), a condenser (11), a vacuum port (13), a collection tank (14), and a stirring paddle (16), characterized in that: A heat insulation layer (4) is provided between the lid (5) and the body (1). The heat insulation layer (4) has holes that run through it from top to bottom. A first water inlet (41) and a first water outlet (42) are provided on the outside of the heat insulation layer (4). The lid (5) has a material outlet (7), a second water inlet (6) and a second water outlet (9). The lid (5) has a pipe (15) that is connected to the condenser (11). The condenser (11) is connected to the vacuum port (13) and the collection tank (14). The stirring paddle (16) is connected to the inner wall of the lid (5) and extends through the heat insulation layer (4) into the body (1). The lower part of the body (1) is connected to the discharge port (3). The outside of the body (1) is connected to the oil heating jacket (2).

2. The apparatus for depolymerizing polycaprolactone into ε-caprolactone monomer according to claim 1, characterized in that: After the condenser (11) is connected to the molecular sieve (12), it is then connected to the vacuum port (13) and the collection tank (14) respectively.

3. The apparatus for depolymerizing polycaprolactone into ε-caprolactone monomer according to claim 1, characterized in that: The stirring paddle (16) is connected to the motor drive by a magnetic coupling.

4. The apparatus for depolymerizing polycaprolactone into ε-caprolactone monomer according to claim 1, characterized in that: The double sealing rings of silicone rubber and polytetrafluoroethylene are used between the lid (5) and the insulation layer (4), and between the insulation layer (4) and the body (1); the base material of the body (1), lid (5), and stirring paddle (16) is 316L, and the materials of the inner wall of the body (1) and lid (5), the outer lining of the stirring paddle (16) and the insulation layer (4) are polytetrafluoroethylene.

5. The apparatus for depolymerizing polycaprolactone into ε-caprolactone monomer according to claim 1, characterized in that: The pipe connection between the material inlet (7) and the vacuum port (13) is made of mechanical seal, and the discharge port (3) is equipped with a discharge ball valve (8).

6. The apparatus for depolymerizing polycaprolactone into ε-caprolactone monomer according to claim 1, characterized in that: The pipeline (15) is wrapped by an insulation sleeve (10); the insulation sleeve (10) is equipped with thermocouples and circulating fluid.

7. The apparatus for depolymerizing polycaprolactone into ε-caprolactone monomer according to claim 1, characterized in that: A high-precision vacuum regulating valve (17) is connected to one side of the vacuum port (13).

8. The apparatus for depolymerizing polycaprolactone into ε-caprolactone monomer according to claim 1, characterized in that: Each of the vessel lid (5) and the insulation layer (4) is provided with a circulating refrigeration unit to supply circulating coolant. The circulating refrigeration unit adjusts the refrigeration temperature by measuring the temperature of the first outlet (42) and the second outlet (9).

9. The apparatus for depolymerizing polycaprolactone into ε-caprolactone monomer according to claim 1, characterized in that: The condenser (11) consists of a spherical condenser (1101) and a serpentine condenser (1102).

10. The apparatus for depolymerizing polycaprolactone into ε-caprolactone monomer according to claim 1, characterized in that: The impeller (16) is a turbine impeller.

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