Drying device for polyimide film production

Abstract

The invention discloses a drying device for polyimide film production. The drying device comprises a drying box body, and a drying unit, a film conveying system and a control system are arranged in the drying box body; the drying unit comprises a heating element and a heat exchange system; the heating element is arranged below the inner top wall of the drying box body; the heat exchange system comprises a top heat exchanger, flow guide pipes and a bottom heat exchanger, the top heat exchanger is arranged above the heating element, the top heat exchanger is connected with a plurality of flow guide pipes, and the flow guide pipes are connected with the bottom heat exchanger located on the inner bottom wall of the drying box body. By arranging the heat exchange system, heat can be effectively recycled and redistributed, the situation that the thin film is locally overheated or insufficient in heat is avoided, the drying uniformity is improved, meanwhile, the thin film is suspended through the air suspension nozzles, uneven heat generated by contact is reduced, and the quality of the thin film is improved.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of polyimide film production, and specifically to a drying device for polyimide film production. Background Art

[0002] Polyimide is one of the organic polymer materials with the best comprehensive performance, and polyimide film is the most common material made of polyimide. When producing polyimide film, the polyamic acid resin is generally formed into a film by a scraper or an extrusion die, and then dried and shaped in a casting machine, and then peeled and sent to a stretching machine, where it is heated and dried by a drying equipment, so that it is finally imidized into a film.

[0003] The prior art discloses a device for uniformly drying a polyimide film, including a horizontal drying box, wherein both the front and rear ends of the horizontal drying box are provided with inlets and outlets, and further comprising: a closed drying chamber, which is arranged inside the horizontal drying box, and a unit heating box is arranged on the upper side of the closed drying chamber. The present invention heats and dries the polyimide film transported horizontally below by arranging a plurality of electric heating tubes in the unit heating box arranged on the upper side of the closed drying chamber, and the electric heating tube can be moved up and down to adjust the height, i.e., the distance between the electric heating tube and the film below, so that the position of the electric heating tube from the middle to each position on both sides can be adjusted, and the lateral temperature difference can be adjusted to improve the uniformity of drying and heating, so that the heating temperature of each part of the film is the same, which is conducive to maintaining the balance of the imidization degree of each part of the film, thereby improving the production quality of the polyimide film.

[0004] However, although the above technologies have multiple heating and adjustment methods, the heat distribution is still not uniform, resulting in large differences in heating of different parts of the film, making it difficult to ensure the consistency of the film thickness, and prone to partial over-drying or under-drying. At the same time, during the drying process, the friction between the film and the internal components of the drying device may also cause scratches on the film surface or generate static electricity, affecting product quality. Summary of the invention

[0005] The present invention mainly provides a drying device for producing polyimide film, which is used to solve the technical problems raised in the above background technology.

[0006] The technical solution adopted by the present invention to solve the above technical problems is: A drying device for producing polyimide film, comprising a drying box, wherein a drying unit, a film transmission system and a control system are arranged in the drying box; The drying unit comprises a heating element and a heat exchange system, wherein the heating element is arranged below the top wall of the drying box; The heat exchange system includes a top heat exchanger, a guide tube and a bottom heat exchanger. The top heat exchanger is arranged above the heating element and is connected to a plurality of the guide tubes. The guide tubes are connected to the bottom heat exchanger located on the bottom wall of the drying box.

[0007] Preferably, the top heat exchanger is a wavy fin heat exchanger structure, in which a plurality of groups of fine flow channels are arranged inside and connected to the guide tube. The bottom heat exchanger is composed of a plurality of exchange units, the number of the exchange units is consistent with the guide tube, and the exchange units are equidistantly arranged on the inner bottom wall of the drying box.

[0008] Preferably, a heat insulating layer is provided between the top heat exchanger and the inner top wall of the drying box body, and the heat insulating layer is also provided between each of the exchange units and the inner bottom wall of the drying box body.

[0009] Preferably, the film transmission system comprises an air suspension nozzle and a transmission roller group, the air suspension nozzle is arranged in the bottom wall of the drying box, and the air suspension nozzle is connected to an external high-pressure air source through a high-pressure valve connected to the outer wall of the drying box, and the high-pressure valve is electrically connected to the control system; The transmission roller groups are provided in a plurality of groups and are arranged equidistantly above the bottom heat exchanger.

[0010] Preferably, the air suspension nozzles are distributed in an array on the bottom wall of the drying box, and are made of high temperature resistant and wear resistant stainless steel. In addition, the surface of the air suspension nozzles is coated with a layer of corrosion resistant coating.

[0011] Preferably, the transmission roller group includes a rotating shaft, one end of the rotating shaft is rotatably connected to the inner wall of the drying box body through a bearing seat, and the other end passes through the inner wall of the drying box body through a sealed bearing and is connected to a driven gear, and three equidistantly arranged transmission rollers are provided on the rotating shaft. In addition, the driven gear is connected to a driving unit through a transmission.

[0012] Preferably, the transmission roller is a multi-layer structure, the inner layer of which uses a relatively high-strength hard plastic as a supporting skeleton, and the outer layer is coated with a composite layer of soft and smooth high-molecular polyethylene and silicone rubber.

[0013] Preferably, the driving unit comprises a driving motor, an output end of the driving motor is rotatably connected to a driving gear, the driving gear is transmission-connected to a plurality of the driven gears via a chain, and in addition, the driving motor is electrically connected to the control system.

[0014] Preferably, the control system comprises a PLC controller, the PLC controller is electrically connected with a temperature sensor, a pressure sensor and a flow sensor, and the temperature sensor is installed on the top heat exchanger and the bottom heat exchanger; The pressure sensor and the flow sensor are installed on the high-pressure valve on the outer wall of the drying box.

[0015] Preferably, the drying box body is provided with an inlet and outlet, and the inlet and outlet are provided with a sealing door.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The heat exchange system provided in the present invention can effectively recover and redistribute heat, avoid local overheating or insufficient heat of the film, and improve the uniformity of drying. At the same time, the air suspension nozzle suspends the film, reducing the uneven heat generated by contact and improving the quality of the film.

[0017] 2. The present invention uses an air suspension nozzle to suspend the film in the air, avoiding contact with solid surfaces such as support rollers or conveyor belts in traditional transmission methods, eliminating uneven heat generated by friction and the risk of surface scratches and contamination. The specially designed transmission roller group uses a soft and smooth outer layer material to gently contact the suspended film, further reducing the possibility of film damage, ensuring the integrity and smoothness of the film surface, and effectively improving the product yield and quality stability.

[0018] 3. The air suspension nozzle and the transmission roller group work together to achieve smooth and uniform transmission of the film. The air suspension system provides frictionless suspension support, and the transmission roller group accurately controls the forward momentum of the film. The combination of the two prevents the film from getting stuck, shaking or deviating during the drying process, ensuring the continuity and stability of the drying process, reducing downtime caused by transmission failures, and thus improving overall production efficiency.

[0019] 4. The control system adjusts the heating element, the gas supply of the air suspension nozzle and the drive motor of the transmission roller group in real time according to the feedback information of the temperature sensor, pressure sensor and flow sensor. This intelligent and precise control can quickly adapt to the drying requirements of polyimide films of different thicknesses, widths and materials, reducing the process adjustment time, while ensuring that the drying process is always in the best state, further improving production efficiency.

[0020] The present invention will be explained in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 It is a schematic diagram of the back of the overall structure of the present invention; Figure 3 It is a side view of the overall structure of the present invention; Figure 4 It is a schematic diagram of the internal structure of the drying box of the present invention; Figure 5 It is a top view of the bottom wall structure of the drying box body of the present invention; Figure 6 It is a schematic diagram of the heat exchange system structure of the present invention; Figure 7 It is a schematic structural diagram of the top heat exchanger of the present invention; Figure 8 It is a schematic diagram of the structure of the air suspension nozzle of the present invention.

[0022] Description of the drawings: 1. Drying box; 101. Insulation layer; 102. High-pressure valve; 103. Inlet and outlet; 104. Sealing door; 2. Drying unit; 201. Heating element; 3. Film transmission system; 301. Air suspension nozzle; 302. Transmission roller group; 303. Rotating shaft; 304. Driven gear; 305. Transmission roller; 4. Heat exchange system; 401. Top heat exchanger; 402. Flow guide tube; 403. Bottom heat exchanger; 404. Exchange unit; 5. Drive unit; 501. Drive motor; 502. Driving gear; 503. Chain; 6. Control system; 601. PLC controller; 602. Temperature sensor; 603. Pressure sensor; 604. Flow sensor. DETAILED DESCRIPTION

[0023] To facilitate understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings, but the present invention can be implemented in different forms and is not limited to the embodiments described in the text. On the contrary, these embodiments are provided to make the content disclosed in the present invention more thorough and comprehensive. Example

[0024] Please refer to the attached Figure 1 , 2, 3, 4, 5, 6, 7, 1. A drying device for producing polyimide film, comprising a drying box 1, characterized in that: The drying box 1 is provided with an inlet and outlet port 103, and a sealing door 104 is provided on the inlet and outlet port 103. The drying box 1 is modularly designed, and several drying boxes 1 can be used in combination; a drying unit 2, a film transmission system 3 and a control system 6 are arranged in the drying box 1; the drying unit 2 includes a heating element 201 and a heat exchange system 4, and the heating element 201 is arranged below the inner top wall of the drying box 1; the heat exchange system 4 includes a top heat exchanger 401, a guide pipe 402 and a bottom heat exchanger 403, the top heat exchanger 401 is arranged above the heating element 201, and the top heat exchanger 401 is connected to several guide pipes 402, and the guide pipes 402 are connected to the bottom heat exchanger 403 located on the inner bottom wall of the drying box 1, in addition, a heat insulation layer 101 is arranged between the top heat exchanger 401 and the inner top wall of the drying box 1, and the heat insulation layer 101 is also arranged between each exchange unit 404 and the inner bottom wall of the drying box 1.

[0025] It should be noted that the top heat exchanger 401 is a corrugated fin heat exchanger structure, which is made of aluminum alloy with high thermal conductivity. The corrugated fins increase the contact area with the hot air. A plurality of groups of fine flow channels are arranged inside the heat exchanger, which are connected to the guide tube 402 for the circulation of heat medium (such as thermal oil or special heat transfer liquid).

[0026] It should be noted that the bottom heat exchanger 403 is composed of a plurality of exchange units 404, the number of which is consistent with the guide tube 402, and a special heat-absorbing coating is used on the surface, and the exchange units 404 are equidistantly arranged on the inner bottom wall of the drying box 1. During drying, the bottom heat exchanger 403 can effectively recover the heat conducted by the film, and at the same time, its internal flow channel is connected to the flow channel of the top heat exchanger 401 through the guide tube 402, forming a complete heat medium circulation loop.

[0027] It should be noted that the guide tube 402 is made of a high-temperature resistant stainless steel tube, and the inside of the tube is smooth to reduce the resistance to the flow of the heat medium. During drying, the temperature of the heat medium in the bottom heat exchanger 403 is relatively low because it mainly absorbs the heat conducted from the film; while the temperature of the heat medium in the top heat exchanger 401 will increase after absorbing the heat conducted upward from the heating unit 201. The existence of this temperature difference is one of the driving forces for the circulation of the heat medium. According to the principle of heat conduction, heat is always transferred from a high-temperature area to a low-temperature area, so the heat medium will naturally flow from the top heat exchanger 401 with a higher temperature to the bottom heat exchanger 403 with a lower temperature to achieve heat circulation.

[0028] It should be noted that the heat insulation layer 101 provided between the top heat exchanger 401 and the inner top wall of the drying box 1 and between the bottom exchange unit 404 and the inner bottom wall significantly reduces the rate of heat conduction to the external environment of the box. The heat insulation layer 101 is made of materials with low thermal conductivity, such as ceramic fiber, rock wool or aerogel, etc. These materials contain a large number of tiny pores or fiber structures, which can effectively hinder the transfer of heat. By reducing heat loss, not only the energy utilization efficiency is improved and the production cost is reduced, but also the temperature inside the drying box 1 can be made more stable, which is conducive to the uniform drying of the polyimide film. Please refer to the attached Figure 2 , 3 As shown in FIGS. 4, 5 and 8, the film transmission system 3 includes an air suspension nozzle 301 and a transmission roller group 302. The air suspension nozzle 301 is arranged in the bottom wall of the drying box 1, and the air suspension nozzle 301 is connected to the external high-pressure gas source through a high-pressure valve 102 connected to the outer wall of the drying box 1, and the high-pressure valve 102 is electrically connected to the control system 6; the transmission roller group 302 has several groups and is equidistantly arranged above the bottom heat exchanger 403, and the transmission roller group 302 includes a rotating shaft 303, one end of which is connected to the drying box through a bearing seat. 1 is rotatably connected to the inner wall of the drying box body 1, and the other end is connected to a driven gear 304 through a sealed bearing penetrating the inner wall of the drying box body 1, and three equidistantly arranged transmission rollers 305 are provided on the rotating shaft 303. In addition, the driven gear 304 is connected to a driving unit 5 through transmission; the driving unit 5 includes a driving motor 501, and the output end of the driving motor 501 is rotatably connected to a driving gear 502, and the driving gear 502 is transmission-connected to a plurality of driven gears 304 through a chain 503. In addition, the driving motor 501 is electrically connected to the control system 6.

[0029] It should be noted that the air suspension nozzle 301 adopts a special Laval nozzle structure, which can accelerate the expansion of high-pressure gas in the nozzle, thereby forming a high-speed, uniform airflow at the nozzle outlet, ensuring that the ejected airflow can form a stable air cushion under the film. The control system 6 can accurately adjust the flow rate and pressure of the gas introduced by the high-pressure valve 102 according to the material, thickness and width of the film to meet different production needs; the air suspension nozzles 301 are distributed in an array in the bottom wall of the drying box 1, and the density of the nozzles is relatively large at the starting and end of the film to ensure that the film can be smoothly suspended and lifted and landed; in the middle transmission area of ​​the film, the nozzles are evenly distributed to ensure that the film is always in a stable suspension state during the entire drying process.

[0030] It should be noted that the air suspension nozzle 301 is made of high temperature resistant and wear resistant stainless steel to ensure that the nozzle will not be deformed or damaged during the long-term high temperature and high pressure gas injection process. A layer of anti-corrosion coating is applied to the surface of the nozzle to prevent impurities or moisture in the gas from corroding the nozzle, further improving the service life of the nozzle.

[0031] It should be noted that the air suspension nozzle 301 is arranged between adjacent exchange units 404, avoiding the pipeline of the heat exchange system 4. At the same time, the high-pressure gas sprayed by the air suspension nozzle 301 forms a certain airflow in the drying box 1, which can assist the heat exchange system 4 to uniformly heat the film.

[0032] It should be noted that the transmission roller 305 adopts a multi-layer structure design. The high-strength hard plastic support skeleton of the inner layer gives the roller sufficient rigidity and load-bearing capacity, and can withstand the pressure of the film during the transmission process without obvious deformation; the soft and smooth composite layer of high-molecular polyethylene and silicone rubber coated on the outer layer is the part that is in direct contact with the film. Its softness can adapt to the tiny surface unevenness of the film and reduce scratches and damage to the film; the smooth surface further reduces the friction coefficient between the film and the film, making the friction force on the film during the transmission process more uniform and stable, which helps to improve the transmission accuracy and quality of the film.

[0033] Please refer to the attached Figure 2 , 6 As shown in Figures 7 and 8, the control system 6 includes a PLC controller 601, which is electrically connected to a temperature sensor 602, a pressure sensor 603 and a flow sensor 604. The temperature sensor 602 is installed on the top heat exchanger 401 and the bottom heat exchanger 403; the pressure sensor 603 and the flow sensor 604 are installed on the high-pressure valve 102 on the outer wall of the drying box 1.

[0034] It should be noted that the temperature sensor 602 installed on the heat exchange system 4 can monitor the heat recovery and utilization in real time. According to the temperature requirements in the drying chamber, the heating element 201 is intelligently adjusted to ensure the best energy recovery and utilization effect in different drying stages.

[0035] It should be noted that the control system 6 can control the high-pressure valve 102 to adjust the gas supply pressure and flow rate in real time according to factors such as the material, thickness, transmission speed, and drying process parameters of the film. When the film is thin and light, the high-pressure valve 102 can appropriately reduce the gas supply pressure to prevent the film from being unstable due to excessive airflow impact; for thicker or heavier films, the gas supply pressure is increased accordingly to ensure sufficient support. At the same time, through flow control, the consumption of high-pressure gas can be minimized while meeting the suspension requirements, thereby improving energy efficiency.

[0036] It should be noted that a close electrical connection is established between the air suspension nozzle 301 and the control system 6, so that the entire film transmission system 3 can realize intelligent operation. The control system 6 monitors the air supply pressure at the air suspension nozzle 301 in real time through the pressure sensor 603. Once the pressure deviates from the set value, it immediately sends a command to the high-pressure valve 102 for adjustment. In addition, combined with the film transmission speed sensor and the feedback information of the temperature sensor 602 in the drying box 1, the control system 6 can comprehensively judge the state changes of the film during the drying process and dynamically optimize the air supply parameters of the air suspension nozzle 301. When the film transmission speed increases, the control system 6 will predict in advance and appropriately increase the air supply pressure of the air suspension nozzle 301 to ensure that the film can still be stably suspended during high-speed movement and ensure the consistency of drying quality.

[0037] The specific operation process of the present invention is as follows: First, the power of the PLC controller 601 is turned on, and the heating temperature, the air supply pressure and flow rate of the air suspension nozzle 301, the film transmission speed and other parameters are set on the PLC controller 601 according to the material, thickness, width and drying process requirements of the polyimide film; Then, the PLC controller 601 starts the heating element 201 to start heating according to the set parameters, and at the same time opens the high-pressure valve 102 connected to the air suspension nozzle 301 to allow the high-pressure gas to enter the nozzle array, opens the sealing door 104 of the feed inlet, and introduces one end of the polyimide film into the drying box 1 so that it is located above the air suspension nozzle 301 and initially suspended, and then closes the sealing door 104. The PLC controller 601 starts the driving motor 501 of the driving unit 5, and drives the driven gear 304 of the transmission roller group 302 to rotate through the driving gear 502 and the chain 503, so that the transmission roller 305 starts to operate, driving the film to be uniformly transmitted forward in the drying box 1; The temperature sensor 602 monitors the temperature of the top heat exchanger 401 and the bottom heat exchanger 403 in real time, and the pressure sensor 603 and the flow sensor 604 monitor the air supply pressure and flow at the high-pressure valve 102 respectively. The PLC controller 601 dynamically adjusts the power of the heating element 201 to maintain the set drying temperature according to the sensor feedback information, and adjusts the opening of the high-pressure valve 102 to control the air supply parameters of the air suspension nozzle 301 to ensure stable suspension and uniform drying of the film. At the same time, according to the feedback of the film transmission speed sensor, the speed of the drive motor 501 is fine-tuned to ensure accurate control of the film transmission speed.

[0038] The above is an exemplary description of the present invention in combination with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as such non-substantial improvements are made by adopting the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A drying device for producing polyimide film, comprising a drying box (1), characterized in that: The drying box (1) is provided with a drying unit (2), a film transmission system (3) and a control system (6); The drying unit (2) comprises a heating element (201) and a heat exchange system (4); the heating element (201) is arranged below the top wall of the drying box (1); The heat exchange system (4) comprises a top heat exchanger (401), a flow guide pipe (402) and a bottom heat exchanger (403); the top heat exchanger (401) is arranged above the heating element (201), and the top heat exchanger (401) is connected to a plurality of the flow guide pipes (402); the flow guide pipes (402) are connected to the bottom heat exchanger (403) located on the inner bottom wall of the drying box (1).

2. A drying device for producing polyimide film according to claim 1, characterized in that: The top heat exchanger (401) is a wave-shaped fin heat exchanger structure, and a plurality of groups of fine flow channels are arranged inside the top heat exchanger to communicate with the guide tube (402). The bottom heat exchanger (403) is composed of a plurality of exchange units (404), the number of the exchange units (404) is the same as the number of the guide tube (402), and the exchange units (403) are arranged equidistantly on the inner bottom wall of the drying box (1).

3. A drying device for producing polyimide film according to claim 2, characterized in that: A heat insulating layer (101) is provided between the top heat exchanger (401) and the inner top wall of the drying box (1); the heat insulating layer (101) is also provided between each of the exchange units (404) and the inner bottom wall of the drying box (1).

4. A drying device for producing polyimide film according to claim 1, characterized in that: The film transmission system (3) comprises an air suspension nozzle (301) and a transmission roller group (302); the air suspension nozzle (301) is arranged in the bottom wall of the drying box (1), and the air suspension nozzle (301) is connected to an external high-pressure air source via a high-pressure valve (102) connected to the outer wall of the drying box (1); the high-pressure valve (102) is electrically connected to the control system (6); The transmission roller groups (302) include a plurality of groups and are arranged equidistantly above the bottom heat exchanger (403).

5. A drying device for producing polyimide film according to claim 4, characterized in that: The air suspension nozzles (301) are distributed in an array on the bottom wall of the drying box (1), and the air suspension nozzles (301) are made of high-temperature resistant and wear-resistant stainless steel material. In addition, the surface of the air suspension nozzles (301) is coated with a layer of anti-corrosion coating.

6. A drying device for producing polyimide film according to claim 4, characterized in that: The transmission roller assembly (302) comprises a rotating shaft (303), one end of the rotating shaft (303) being rotatably connected to the inner wall of the drying box (1) via a bearing seat, and the other end of the rotating shaft (303) penetrating the inner wall of the drying box (1) via a sealed bearing and being connected to a driven gear (304), and three transmission rollers (305) arranged at equal distances are provided on the rotating shaft (303), and in addition, the driven gear (304) is connected to a driving unit (5) via a transmission.

7. A drying device for producing polyimide film according to claim 6, characterized in that: The transmission roller (305) is a multi-layer structure, wherein the inner layer uses a relatively high-strength hard plastic as a supporting skeleton, and the outer layer is coated with a composite layer of soft and smooth high-molecular polyethylene and silicone rubber.

8. A drying device for producing polyimide film according to claim 6, characterized in that: The driving unit (5) comprises a driving motor (501), the output end of the driving motor (501) being rotatably connected to a driving gear (502), the driving gear (502) being transmission-connected to a plurality of the driven gears (304) via a chain (503), and the driving motor (501) being electrically connected to the control system (6).

9. A drying device for producing polyimide film according to claim 1, characterized in that: The control system (6) comprises a PLC controller (601), the PLC controller (601) being electrically connected to a temperature sensor (602), a pressure sensor (603) and a flow sensor (604), and the temperature sensor (602) being installed on the top heat exchanger (401) and the bottom heat exchanger (403); The pressure sensor (603) and the flow sensor (604) are mounted on the high-pressure valve (102) on the outer wall of the drying box (1).

10. A drying device for producing polyimide film according to claim 1, characterized in that: The drying box (1) is provided with an inlet and outlet port (103), and the inlet and outlet port (103) is provided with a sealing door (104). The drying box (1) is modularly designed, and a plurality of drying boxes (1) can be combined for use.

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