Micromolecule removal equipment for nylon polymer melt

Abstract

The utility model discloses small molecule removal equipment for nylon polymer melt, which comprises a shell and a vacuum cavity arranged in the shell, a hollow rotating shaft is rotatably arranged in the vacuum cavity, a distributor and a scraper blade positioned below the distributor are arranged on the hollow rotating shaft, a gas inlet for inputting wet nitrogen is arranged on the shell, and a gas outlet is arranged on the shell. The gas inlet penetrates through the hollow rotating shaft, and gas holes penetrating through the hollow rotating shaft are formed in the side wall of the scraper. According to the scheme, the content of volatile components in the nylon polymer melt is greatly reduced, the nylon polymer melt can be directly spun, compared with existing slice intermittent spinning, the production process can be greatly simplified through melt direct spinning, the nylon polymer fiber is produced through direct spinning of the nylon polymer melt, the production efficiency is improved, and the production cost is reduced. The production cost of the nylon polymer fiber is greatly reduced; the temperature of the nylon polymer melt is uniform, the fluidity of the nylon polymer melt is good, and the spinning forming performance of the nylon polymer melt is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of nylon material production, in particular to a small molecule removal device for nylon polymer melt. Background Art

[0002] The conversion rate of nylon 6 by hydrolysis polymerization of caprolactam is generally around 90%, which means that about 10% of caprolactam monomers and oligomers (also known as hot water extractables, of which monomers account for about 75% and oligomers account for about 25%) remain in the nylon polymer. These small molecules in the melt, especially caprolactam monomers, have a great impact on spinning. Therefore, before spinning polymers containing nylon 6 such as nylon 6 and nylon 6 / 66 copolymers, it is necessary to extract the slices and then spin the slices intermittently. At present, the industry generally adopts a hot water continuous extraction process to extract monomers and oligomers from polymer slices containing nylon 6 such as nylon 6 and nylon 6 / 66 copolymers to meet the requirements of high-speed spinning. However, a large amount of water and energy are consumed in the extraction, drying, and remelting process, which greatly increases the production cost and carbon emissions of polymer fibers containing nylon 6.

[0003] For example, Chinese patent publication number CN100348644C, published on November 14, 2007, entitled "Method for Reducing Caprolactam and Its Oligomers in Nylon-6 Prepolymer", comprises: (a) subjecting the molten prepolymer mixture to a sudden pressure drop discharge, wherein the pressure drop is at least 345 kPa; (b) contacting the prepolymer mixture discharged from step (a) with water to form a prepolymer phase and an aqueous phase, and the contact time should be sufficient to allow at least a portion of the caprolactam and oligomers to be extracted into the aqueous phase; and (c) separating the prepolymer phase from the aqueous phase.

[0004] The disadvantage of the existing patent is that the slices of the existing nylon polymer need to be continuously extracted with hot water before spinning, which consumes a large amount of water and energy, increasing the production cost of the nylon polymer fiber. Utility Model Content

[0005] The utility model aims to solve the problem that a large amount of water and energy are needed to continuously treat slices with hot water before spinning of existing nylon polymers, thereby increasing the production cost of nylon polymer fibers, and to provide a small molecule removal device for nylon polymer melts which reduces the production cost of nylon polymer fibers and reduces production energy consumption.

[0006] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0007] A small molecule removal device for nylon polymer melt comprises a shell and a vacuum chamber arranged in the shell, a hollow shaft is rotatably arranged in the vacuum chamber, a distributor and a scraper below the distributor are arranged on the hollow shaft, a gas inlet for inputting wet nitrogen is arranged on the shell, the gas inlet passes through the hollow shaft, and a pore passing through the hollow shaft is arranged on the side wall of the scraper. The small molecule removal device for nylon polymer melt described in this scheme is used to remove small molecules such as caprolactam monomers and oligomers in nylon polymer melt, so that the volatile content in the nylon polymer melt is greatly reduced, so that the nylon polymer melt can be directly spun. Compared with the existing slice intermittent spinning, melt direct spinning can greatly simplify the production process. The nylon polymer melt is directly spun to produce nylon polymer fibers, which improves production efficiency and greatly reduces the production cost of nylon polymer fibers.

[0008] Under certain vacuum conditions, the caprolactam monomer in the nylon polymer melt can volatilize from the nylon polymer melt. In this process, the volatilization of the caprolactam monomer will drive the removal of other small molecular oligomers from the nylon polymer melt. Therefore, equipment is required to give the nylon polymer melt a higher specific surface area and vacuum degree.

[0009] In this solution, the hollow shaft rotates, driving the distributor and the scraper to rotate. The nylon polymer melt is evenly distributed on the inner wall of the shell through the distributor. The nylon polymer melt flows down from the top along the inner wall of the shell under the action of gravity, and the rotating scraper spreads the flowing nylon polymer melt evenly on the inner wall of the shell. The shell is heated and the inside of the shell is evacuated. The melt on the inner surface of the shell has a large specific surface area. A large amount of volatiles are removed under the action of vacuum, and the volatile content of the melt is reduced. The melt on the scraper surface can be exchanged to the inner surface of the shell to continue to remove monomers. Finally, all volatiles in the melt are evenly removed, and the volatiles leave the shell. The melt after the small molecules are removed can be discharged from the shell. Since the nylon polymer melt is continuously and evenly spread on the inner wall of the shell by the scraper, the nylon polymer melt is prevented from affecting the subsequent spinning performance of the nylon polymer melt due to poor uniformity during the volatile removal process. This solution makes the temperature of the nylon polymer melt uniform and the fluidity of the nylon polymer melt good, thereby improving the spinning performance of the nylon polymer melt.

[0010] Under the above conditions, the nylon polymer melt adheres to the scraper surface and the inner wall of the shell, and the nitrogen containing trace moisture sweeps out of the scraper through the hollow shaft and pores and enters the nylon polymer melt on the scraper surface, and enters the nylon polymer melt on the inner surface of the shell with the exchange of substances, so that the polymer melt containing nylon 6, such as nylon 6 and nylon 6 / 66 copolymer on the inner surface of the shell, bubbles are generated, which promotes the formation, growth and rupture of bubbles, accelerates the process of volatiles transferring from the melt to the bubbles and then to the gas phase, and improves the removal efficiency. When the bubbles in the nylon polymer melt increase to a certain extent, they will rupture, and the gas will be taken away from the shell under the action of vacuum. In addition, since volatile components such as caprolactam monomer have good solubility in hot water, and non-volatile components such as small molecular oligomers have good solubility in caprolactam monomer. Therefore, the moisture in the hot nitrogen gas flow can interact with volatile components such as caprolactam monomer and non-volatile components such as oligomers, drive the volatilization of non-volatile components, reduce the content of non-volatile components in the nylon polymer melt, thereby further reducing the content of hot water extractables in the nylon polymer melt, and improving the quality and spinnability of the nylon polymer melt. Finally, the gas containing volatile components is discharged from the shell.

[0011] Preferably, the pores are located at the upper part of the scraper, and the pores are located on one side of the scraper close to the inner wall of the shell. The pores are evenly distributed on the scraper, so that the wet nitrogen can be swept out of the nylon polymer melt adhering to the scraper through the pores, and the nylon polymer melt on the inner wall of the shell is exchanged with the scraper, so that the polymer melt containing nylon 6 such as nylon 6 and nylon 6 / 66 copolymer on the inner surface of the shell is bubbled, which promotes the formation, growth and rupture of bubbles, accelerates the process of volatiles transferring from the melt to the bubbles and then to the gas phase, and improves the removal efficiency. Specifically, the pores of the scraper are distributed on the upper outer side of the scraper, and the pores are arranged obliquely downward, which can prevent the melt from flowing into the holes, and is also conducive to the flow of gas. The area without pores at the bottom of the scraper can quickly remove moisture from the system to meet the spinning requirements.

[0012] Preferably, the scraper is provided with a branch pipe, one end of the branch pipe is connected to the air hole, and the other end is connected to the hollow shaft. The wet nitrogen is blown out of the air hole through the hollow shaft and the branch pipe.

[0013] Preferably, the shell is provided with a melt inlet, which is located above the distributor. The polymer melt containing nylon 6, such as nylon 6 and nylon 6 / 66 copolymer, enters the distributor through the melt inlet, and the distributor rotates to distribute the melt on the inner wall of the shell.

[0014] Preferably, a double spiral belt is provided at the lower end of the hollow shaft, and a melt outlet is provided at the lower end of the shell, and the double spiral belt is located in the melt outlet. The nylon polymer melt after the removal of small molecules is discharged along the melt outlet through the double spiral belt, and the shaft drives the double spiral belt to rotate, so that the nylon polymer melt after the reaction in the shell is discharged outside the shell, and the melt outlet is located at the lower part of the shell.

[0015] Preferably, the shell is further provided with a gas outlet, the gas outlet is located at the upper part of the shell, and the gas outlet and the melt inlet are respectively located at two opposite sides of the shell. The gas phase of the nylon polymer melt after reaction is discharged from the gas outlet.

[0016] Preferably, a vacuum system is disposed outside the shell, and the vacuum system is connected to the gas outlet to discharge the gas phase while maintaining the vacuum state of the vacuum chamber in the shell.

[0017] Preferably, a heating layer is provided on the outside of the shell, and the heating layer is evenly distributed on the outside of the shell. The heating layer heats the shell so that the temperature of the inner wall of the shell is uniform.

[0018] Preferably, there are multiple scrapers, and the scrapers are distributed on the hollow shaft in a circular shape according to the central axis of the hollow shaft.

[0019] Preferably, a support plate is provided on the outer wall of the hollow shaft, the scraper is fixed on the support plate by fasteners, and an elliptical opening for adjusting the position of the scraper is provided on the scraper. A support tube and a circular hole are provided on the support plate, and when the support plate and the scraper are connected, the support tube and the support are connected, and the elliptical opening is used to adjust the distance between the scraper and the inner wall of the shell.

[0020] Therefore, the utility model has the following beneficial effects: it greatly reduces the volatile content in the nylon polymer melt, so that the nylon polymer melt can be directly spun. Compared with the existing slice intermittent spinning, melt direct spinning can greatly simplify the production process. The nylon polymer melt is directly spun to produce nylon polymer fibers, which improves production efficiency and greatly reduces the production cost of nylon polymer fibers; the temperature of the nylon polymer melt is uniform, and the fluidity of the nylon polymer melt is better, thereby improving the performance of the nylon polymer melt spinning. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the utility model.

[0022] Figure 2 It is a structural schematic diagram of the hollow rotating shaft, distributor and scraper of the utility model.

[0023] As shown in the figure:

[0024] Shell 1, vacuum chamber 1.1, gas inlet 1.2, melt inlet 1.3, melt outlet 1.4, gas outlet 1.5,

[0025] Hollow shaft 2, support plate 2.1,

[0026] Distributor 3,

[0027] Scraper 4, air hole 4.1, branch pipe 4.2, elliptical opening 4.3,

[0028] Double spiral belt 5, heating interlayer 6. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the technical solution embodiments of the utility model clearer, the utility model is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0030] Embodiment 1, as Figure 1 , Figure 2 The device for removing small molecules from a nylon polymer melt shown in the figure comprises a shell 1 and a vacuum chamber 1.1 arranged in the shell 1, a hollow shaft 2 is rotatably arranged in the vacuum chamber 1.1, a distributor 3 and a scraper 4 located below the distributor 3 are arranged on the hollow shaft 2, a gas inlet 1.2 for inputting wet nitrogen is arranged on the shell 1, the gas inlet 1.2 passes through the hollow shaft 2, and an air hole 4.1 passing through the hollow shaft 2 is arranged on the side wall of the scraper 4.

[0031] A small molecule removal device for nylon polymer melt in the above embodiment is used to remove small molecules such as caprolactam monomers and oligomers in the nylon polymer melt, so that the volatile content in the nylon polymer melt is greatly reduced, so that the nylon polymer melt can be directly spun. Compared with the existing intermittent spinning of slices, melt direct spinning can greatly simplify the production process. The nylon polymer melt is directly spun to produce nylon polymer fibers, improve production efficiency, and greatly reduce the production cost of nylon polymer fibers. It solves the problem that a large amount of water and energy are needed to continuously treat the slices with hot water before the existing nylon polymer spinning, which increases the production cost of nylon polymer fibers.

[0032] Under certain vacuum conditions, the caprolactam monomer in the nylon polymer melt can volatilize from the nylon polymer melt. In this process, the volatilization of the caprolactam monomer will drive the removal of other small molecular oligomers from the nylon polymer melt. Therefore, equipment is required to give the nylon polymer melt a higher specific surface area and vacuum degree.

[0033] In this solution, the hollow shaft 2 rotates, driving the distributor 3 and the scraper 4 to rotate. The nylon polymer melt is evenly distributed on the inner wall of the shell 1 through the distributor 3. The nylon polymer melt flows down from the upper part along the inner wall of the shell 1 under the action of gravity. The rotating scraper 4 evenly spreads the flowing nylon polymer melt on the inner wall of the shell 1. The shell 1 is heated and the inside of the shell 1 is evacuated. The melt on the inner surface of the shell 1 has a large specific surface area. A large amount of volatiles are removed under the action of vacuum, and the volatile content of the melt is reduced. The melt on the surface of the scraper 4 can be exchanged to the inner surface of the shell 1 to continue to remove monomers. Finally, all volatiles in the melt are evenly removed, and the volatiles leave the shell 1. The melt after the small molecules are removed can be discharged from the shell 1. Since the nylon polymer melt is continuously and evenly spread on the inner wall of the shell 1 through the scraper 4, the nylon polymer melt is prevented from affecting the subsequent spinning performance of the nylon polymer melt due to poor uniformity during the volatile removal process. This solution makes the temperature of the nylon polymer melt uniform and the fluidity of the nylon polymer melt good, thereby improving the spinning performance of the nylon polymer melt.

[0034] Under the above conditions, the nylon polymer melt adheres to the surface of the scraper 4 and the inner wall of the shell 1, and the nitrogen containing trace moisture sweeps out of the scraper 4 through the hollow shaft 2 and the air hole 4.1 and enters the nylon polymer melt on the surface of the scraper 4, and enters the nylon polymer melt on the inner surface of the shell 1 with the exchange of substances, so that the polymer melt containing nylon 6 such as nylon 6 and nylon 6 / 66 copolymer on the inner surface of the shell 1 is bubbled, promoting the formation, growth and rupture of bubbles, accelerating the process of volatiles transferring from the melt to the bubbles and then to the gas phase, and improving the removal efficiency. When the bubbles in the nylon polymer melt increase to a certain extent, they will burst, and the gas will be taken away from the shell 1 under the action of vacuum. In addition, since volatile components such as caprolactam monomer have good solubility in hot water, and non-volatile components such as small molecular oligomers have good solubility in caprolactam monomer. Therefore, the moisture in the hot nitrogen gas flow can interact with volatile components such as caprolactam monomer and non-volatile components such as oligomers, drive the volatilization of non-volatile components, reduce the content of non-volatile components in the nylon polymer melt, thereby further reducing the content of hot water extractables in the nylon polymer melt and improving the quality and spinnability of the nylon polymer melt.

[0035] Embodiment 2, as Figure 1 , Figure 2 The device for removing small molecules from a nylon polymer melt shown in the figure comprises a shell 1 and a vacuum chamber 1.1 arranged in the shell 1, a hollow shaft 2 is rotatably arranged in the vacuum chamber 1.1, a distributor 3 and a scraper 4 located below the distributor 3 are arranged on the hollow shaft 2, a gas inlet 1.2 for inputting wet nitrogen is arranged on the shell 1, the gas inlet 1.2 passes through the hollow shaft 2, and an air hole 4.1 passing through the hollow shaft 2 is arranged on the side wall of the scraper 4.

[0036] Specifically, Figure 1 , Figure 2 As shown, the pores 4.1 are located at the upper part of the scraper 4, and the pores 4.1 are located on one side of the scraper 4 close to the inner wall of the shell 1. The pores 4.1 are evenly distributed on the scraper 4, so that the wet nitrogen can be swept out of the nylon polymer melt adhering to the scraper 4 through the pores 4.1, and the nylon polymer melt on the inner wall of the shell 1 is exchanged with the nylon polymer melt through the scraper 4, so that the polymer melt containing nylon 6 such as nylon 6 and nylon 6 / 66 copolymer on the inner surface of the shell 1 is bubbled, which promotes the formation, growth and rupture of bubbles, accelerates the process of volatiles transferring from the melt to the bubbles and then to the gas phase, and improves the removal efficiency. Specifically, the pores 4.1 of the scraper 4 are distributed on the upper outer part of the scraper 4, and the pores 4.1 are arranged obliquely downward, which can prevent the melt from flowing into the holes, and is also conducive to the flow of gas. The area without pores 4.1 at the bottom of the scraper 4 can quickly remove moisture from the system to meet the spinning requirements.

[0037] In this embodiment, Figure 1 , Figure 2 As shown, the scraper 4 is provided with a branch pipe 4.2, one end of the branch pipe 4.2 is connected to the air hole 4.1, and the other end is connected to the hollow shaft 2. The wet nitrogen is blown out of the air hole 4.1 through the hollow shaft 2 and the branch pipe 4.2. A support plate 2.1 is provided on the outer wall of the hollow shaft 2, and the scraper 4 is fixed on the support plate 2.1 by fasteners. The scraper 4 is provided with an elliptical opening 4.3 for adjusting the position of the scraper 4. A support tube and a circular hole are provided on the support plate 2.1. When the support plate 2.1 and the scraper 4 are connected, the support tube and the branch are connected, and the elliptical opening is used to adjust the distance between the scraper 4 and the inner wall of the housing 1.

[0038] In this embodiment, Figure 1 , Figure 2As shown, the shell 1 is provided with a melt inlet 1.3, and the melt inlet 1.3 is located above the distributor 3. The polymer melt containing nylon 6, such as nylon 6 and nylon 6 / 66 copolymer, enters the distributor 3 through the melt inlet 1.3, and the distributor 3 rotates to distribute the melt on the inner wall of the shell 1. The lower end of the hollow shaft 2 is provided with a double screw belt 5, and the lower end of the shell 1 is provided with a melt outlet 1.4, and the double screw belt 5 is located in the melt outlet 1.4. The nylon polymer melt after the removal of small molecules is discharged along the melt outlet 1.4 through the double screw belt 5, and the shaft drives the double screw belt 5 to rotate, so that the nylon polymer melt after the reaction in the shell 1 is discharged outside the shell 1, and the melt outlet 1.4 is located at the lower part of the shell 1. The shell 1 is also provided with a gas outlet 1.5, and the gas outlet 1.5 is located at the upper part of the shell 1. The gas outlet 1.5 and the melt inlet 1.3 are respectively located on opposite sides of the shell 1. The gas phase after the reaction of the nylon polymer melt is discharged from the gas outlet 1.5. A vacuum system is provided outside the housing 1, and the vacuum system is connected to the gas outlet 1.5. While exhausting the gas phase, the vacuum state of the vacuum chamber 1.1 in the housing 1 is maintained. Figure 1 As shown, a heating interlayer 6 is provided on the outside of the shell 1, and the heating interlayer 6 is evenly distributed on the outside of the shell 1. The heating interlayer 6 heats the shell 1, so that the temperature of the inner wall of the shell 1 is uniform.

[0039] Further, such as Figure 1 , Figure 2 As shown, there are multiple scrapers 4 , and the scrapers 4 are distributed on the hollow shaft 2 in a circular shape according to the central axis of the hollow shaft 2 .

[0040] In this embodiment, the inner surface of the shell 1, the distributor 3, the double spiral belt 5, the scraper 4, the hollow shaft 2 and other parts that are in direct contact with the melt or may be in contact with the melt are polished, and the surface roughness requirement is Ra≤0.8.

[0041] Furthermore, the distributor 3 is connected to the hollow shaft 2 by welding with a stainless steel plate, and there is a gap of moderate length between the distributor 3 and the hollow shaft 2, which is conducive to the departure of the gas phase and can prevent the melt from flowing into the gap. The distributor 3 is 10 mm away from the inner surface of the shell 1. In addition, there are small scrapers 4 distributed obliquely on the distributor 3, which can evenly distribute the melt on the inner surface of the shell 1, and there will be no surface not covered by the melt.

[0042] A small molecule removal device for nylon polymer melt in the above-mentioned embodiment is used to remove small molecules such as caprolactam monomer and oligomers in the nylon polymer melt, so that the volatile content in the nylon polymer melt is greatly reduced, so that the nylon polymer melt can be directly spun. Compared with the existing slice intermittent spinning, melt direct spinning can greatly simplify the production process. Nylon polymer melt is directly spun to produce nylon polymer fibers, which improves production efficiency and greatly reduces the production cost of nylon polymer fibers.

[0043] In this solution, the hollow shaft 2 rotates, driving the distributor 3 and the scraper 4 to rotate. The nylon polymer melt is evenly distributed on the inner wall of the shell 1 through the distributor 3. The nylon polymer melt flows down from the upper part along the inner wall of the shell 1 under the action of gravity. The rotating scraper 4 evenly spreads the flowing nylon polymer melt on the inner wall of the shell 1. The shell 1 is heated and the inside of the shell 1 is evacuated. The melt on the inner surface of the shell 1 has a large specific surface area. A large amount of volatiles are removed under the action of vacuum, and the volatile content of the melt is reduced. The melt on the surface of the scraper 4 can be exchanged to the inner surface of the shell 1 to continue to remove monomers. Finally, all volatiles in the melt are evenly removed, and the volatiles leave the shell 1. The melt after the small molecules are removed can be discharged from the shell 1. Since the nylon polymer melt is continuously and evenly spread on the inner wall of the shell 1 through the scraper 4, the nylon polymer melt is prevented from affecting the subsequent spinning performance of the nylon polymer melt due to poor uniformity during the volatile removal process. This solution makes the temperature of the nylon polymer melt uniform and the fluidity of the nylon polymer melt good, thereby improving the spinning performance of the nylon polymer melt.

[0044] Under the above conditions, the nylon polymer melt adheres to the surface of the scraper 4 and the inner wall of the shell 1, and the nitrogen containing trace moisture sweeps out of the scraper 4 through the hollow shaft 2 and the air hole 4.1 and enters the nylon polymer melt on the surface of the scraper 4, and enters the nylon polymer melt on the inner surface of the shell 1 with the exchange of substances, so that the polymer melt containing nylon 6 such as nylon 6 and nylon 6 / 66 copolymer on the inner surface of the shell 1 is bubbled, promoting the formation, growth and rupture of bubbles, accelerating the process of volatiles transferring from the melt to the bubbles and then to the gas phase, and improving the removal efficiency. When the bubbles in the nylon polymer melt increase to a certain extent, they will burst, and the gas will be taken away from the shell 1 under the action of vacuum. In addition, since volatile components such as caprolactam monomer have good solubility in hot water, and non-volatile components such as small molecular oligomers have good solubility in caprolactam monomer. Therefore, the moisture in the hot nitrogen gas flow can interact with volatile components such as caprolactam monomer and non-volatile components such as oligomers, drive the volatilization of non-volatile components, reduce the content of non-volatile components in the nylon polymer melt, and further reduce the content of hot water extractables in the nylon polymer melt, thereby improving the quality and spinnability of the nylon polymer melt. Finally, the gas containing volatile components is discharged from the shell 1, and the obtained nylon 6, nylon 6 / 66 copolymer and other polymer melts containing nylon 6 have a hot water extractable content of ≤3wt%, and the nylon polymer melt can be directly made into plastic products.

[0045] The utility model has the following beneficial effects: the volatile content in the nylon polymer melt is greatly reduced, so that the nylon polymer melt can be directly spun. Compared with the existing intermittent spinning of slices, melt direct spinning can greatly simplify the production process. The nylon polymer melt is directly spun to produce nylon polymer fibers, which improves production efficiency and greatly reduces the production cost of nylon polymer fibers; the temperature of the nylon polymer melt is uniform, and the fluidity of the nylon polymer melt is good, which improves the performance of nylon polymer melt spinning. It solves the problem that a large amount of water and energy are needed to continuously treat slices with hot water before the existing nylon polymer spinning, which increases the production cost of nylon polymer fibers.

[0046] The specific embodiments described above are only preferred implementations of the present invention, and are not intended to limit the specific implementation scope of the present invention. All equivalent changes made in accordance with the shape and structure of the present invention should be included in the protection scope of the present invention.

Claims

1. A small molecule removal device for nylon polymer melt, characterized in that: It comprises a shell and a vacuum chamber arranged in the shell, wherein a hollow shaft is rotatably arranged in the vacuum chamber, a distributor and a scraper located below the distributor are arranged on the hollow shaft, a gas inlet for inputting wet nitrogen is arranged on the shell, the gas inlet passes through the hollow shaft, and an air hole passing through the hollow shaft is arranged on the side wall of the scraper.

2. The small molecule removal device for nylon polymer melt according to claim 1, characterized in that: The air hole is located at the upper part of the scraper, and the air hole is located on a side of the scraper close to the inner wall of the shell.

3. The small molecule removal device for nylon polymer melt according to claim 2, characterized in that: The scraper is provided with a branch pipe, one end of which is connected to the air hole, and the other end of which is connected to the hollow rotating shaft.

4. A small molecule removal device for nylon polymer melt according to claim 1, 2 or 3, characterized in that: The shell is provided with a melt inlet, and the melt inlet is located above the distributor.

5. The small molecule removal device for nylon polymer melt according to claim 4, characterized in that: A double spiral belt is arranged at the lower end of the hollow rotating shaft, a melt outlet is arranged at the lower end of the shell, and the double spiral belt is located in the melt outlet.

6. The small molecule removal device for nylon polymer melt according to claim 5, characterized in that: The shell is also provided with a gas outlet, which is located at the upper part of the shell. The gas outlet and the melt inlet are respectively located at two opposite sides of the shell.

7. The small molecule removal device for nylon polymer melt according to claim 6, characterized in that: A vacuum system is disposed outside the shell, and the vacuum system is connected to the gas outlet.

8. The small molecule removal device for nylon polymer melt according to claim 7, characterized in that: A heating interlayer is arranged on the outside of the shell, and the heating interlayer is evenly distributed on the outside of the shell.

9. A small molecule removal device for nylon polymer melt according to claim 1, 2 or 3, characterized in that: There are multiple scrapers, and the scrapers are distributed on the hollow shaft in a circular shape according to the central axis of the hollow shaft.

10. A small molecule removal device for nylon polymer melt according to claim 1, 2 or 3, characterized in that: A support plate is provided on the outer wall of the hollow rotating shaft, and the scraper is fixed on the support plate by a fastener. An elliptical opening for adjusting the position of the scraper is provided on the scraper.

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