A method for preparing a highly dimensionally stable polyimide film

Abstract

The present invention relates to a method for preparing a highly dimensionally stable polyimide film, comprising a casting and stretching device, the casting and stretching device comprising a base frame, a conveying module, a casting module, and a stretching module. The base frame is provided with a conveying module mounted on the upper end, a casting module mounted on the right side of the upper end of the conveying module, and a stretching module mounted on the left side of the upper end of the conveying module. The present invention can effectively clean the film, preventing a viscous mixed liquid from remaining on the surface of a conveyor belt, thereby preventing impurities from affecting the preparation effect of the polyimide film surface. Furthermore, a release agent can be evenly applied to the surface of the conveyor belt, preventing the viscous mixed liquid from adhering to the conveyor belt, thereby facilitating the separation of the formed polyimide film from the conveyor belt.

Description

Technical Field

[0001] The present invention relates to the field of polyimide film preparation, and in particular to a method for preparing a highly dimensionally stable polyimide film. Background Art

[0002] With the rapid development of the electronic information industry, the high integration, high density and high speed of electronic equipment have caused circuits or chips to accumulate heat rapidly in a very small limited space. Whether heat can be dissipated in time has become the key to affecting the service life, operation stability and safety performance of components.

[0003] Polyimide (PI) has excellent thermal stability, electrical insulation, and mechanical properties, and is widely used in fields such as microelectronics, rail transportation, and aerospace. However, the thermal conductivity of traditional PI film is only around 0.16W / (m·K), making it almost a thermal insulator. When used in microelectronic devices, it is prone to circuit overheating, affecting the stability of components and integrated circuits. To meet the growing demand for insulation and thermal conductivity of components, there is an urgent need to develop a highly thermally conductive polyimide film that can quickly and efficiently transfer and dissipate heat generated by components while maintaining its excellent overall performance, thereby ensuring stable operation and extending the service life of electronic components.

[0004] Currently, the existing polyimide film preparation process generally has the following defects: 1. During the preparation of the existing polyimide film, the mixed raw materials cannot be effectively cleared during the casting process, and the raw materials are prone to clogging during casting, affecting the preparation effect of the polyimide film; 2. During the preparation process of the existing polyimide film, the conveyor belt surface cannot be effectively cleaned, and the raw materials are prone to adhesion, which affects the molding effect of the polyimide film. Summary of the Invention

[0005] (1) Technical issues to be resolved

[0006] The present invention provides a method for preparing a highly dimensionally stable polyimide film, which can solve the above-mentioned technical problems.

[0007] (2) Technical solution

[0008] In view of the problems raised by the above background technology, the purpose of the present invention is to provide a method for preparing a highly dimensionally stable polyimide film. To achieve the above technical purpose, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing a highly dimensionally stable polyimide film comprises the following steps:

[0010] (1) Stirring and mixing raw materials: The raw materials to be processed are evenly filled into the reaction tank. Under the action of nitrogen, the raw materials are evenly stirred and mixed to form a viscous mixed liquid;

[0011] (2) Mixed liquid casting processing: The mixed liquid is subjected to a casting and stretching process, wherein the casting and stretching process uses a casting and stretching device, which is used to stretch the mixed liquid into a film;

[0012] (3) Film trimming and winding: trimming the formed film by cutting, and then winding and fixing the cut film;

[0013] The above-mentioned casting and stretching device includes a base frame, a conveying module, a casting module and a stretching module. The conveying module is installed on the upper end of the base frame, the casting module is installed on the right side of the upper end of the conveying module, and the stretching module is installed on the left side of the upper end of the conveying module.

[0014] The casting module includes a liquid storage tank, a scraper unit and a first liquid inlet pipe. The liquid storage tank is installed on the right side of the upper end of the conveying module, a discharge port is provided on the left side of the liquid storage tank, a scraper unit is installed outside the discharge port, and the first liquid inlet pipe is installed on the upper end of the liquid storage tank. The first liquid inlet pipe is connected to the stirred mixed liquid.

[0015] The scraper unit includes a fixing frame, an adjusting rod, a limiting rod, a liquid storage frame and a scraper branch chain. The fixing frame is installed on the outside of the liquid storage tank. The fixing frame has a U-shaped structure. A threaded seat is installed in the middle of the upper end of the fixing frame. The middle of the threaded seat is connected to the adjusting rod by threaded fit. The lower end of the adjusting rod is connected to the liquid storage frame through a bearing. Through holes are symmetrically provided on the fixing frame. The limiting rod is connected in the through hole by sliding fit. The lower end of the limiting rod is connected to the liquid storage frame. The scraper branch chain is installed at the lower end of the liquid storage frame by screws.

[0016] Preferably, the conveying module includes a connecting frame, a conveyor belt and a cleaning unit. The connecting frame is symmetrically installed on the upper end of the base frame. The width of the left side between the connecting frames is greater than the width of the right side between the connecting frames. Conveyor belts are respectively installed on the left and right sides between the connecting frames. The width of the conveyor belts is adapted to the spacing between the connecting frames. A cleaning unit is installed between the two conveyor belts.

[0017] Preferably, the cleaning unit includes a cleaning frame and guide rollers. The cleaning frame has a triangular structure, the upper end surface of the cleaning frame is flush with the conveyor belt, the upper end surface of the cleaning frame is evenly provided with guide rollers, the outer side surface of the cleaning frame has an arc structure, a liquid storage cavity is provided in the middle of the cleaning frame, and the outer side of the cleaning frame is in contact with the end of the conveyor belt.

[0018] Preferably, through grooves communicating with the liquid storage cavity are evenly arranged on the outside of the cleaning frame, cleaning rollers are installed in the through grooves, and rubber sleeves are arranged on the outside of the cleaning rollers.

[0019] Preferably, the scraper branch chain includes a scraper frame, a second liquid inlet pipe and a rotating roller, the scraper frame is installed at the lower end of the liquid storage frame, a cavity is provided in the middle of the scraper frame, the second liquid inlet pipe communicating with the cavity is installed at the upper end of the scraper frame, and sealing jacks cooperating with the second liquid inlet pipe are evenly provided at the lower end of the liquid storage frame. The lower end surface of the scraper frame is an arc-shaped surface, and spray holes are evenly provided on the lower end surface of the scraper frame. A rotating roller is installed at the lower end of the scraper frame through a bracket, the rotating roller is connected to the output shaft of the motor, and a toggle piece is evenly provided on the rotating roller.

[0020] Preferably, the toggle piece is detachably arranged on the outside of the rotating roller, and the toggle piece is made of hard rubber.

[0021] Preferably, the stretching module includes a mounting frame, a stretching roller, a negative pressure tube, a drying frame, a collecting frame and a condensing tube. The mounting frame is installed at the upper left end of the conveying module, and the stretching roller is symmetrically installed at the lower end of the mounting frame through a bearing. The distance between the stretching roller and the surface of the conveying module is adjustable. A negative pressure tube is installed in the middle of the upper end of the mounting frame, and the drying racks are evenly installed inside the mounting frame. The collecting racks are evenly installed between the upper ends of the drying racks. The cross-section of the collecting rack is a V-shaped structure. Ventilation grooves are provided between adjacent collecting racks. A condensing tube is provided above the collecting rack, and the condensing tube is installed inside the mounting frame.

[0022] (3) Beneficial effects

[0023] 1. The present invention provides a cleaning unit that can effectively clean the surface of the conveyor belt, preventing the viscous mixed liquid from remaining on the conveyor belt surface and preventing impurities from affecting the preparation effect of the polyimide film surface.

[0024] 2. The present invention provides a cleaning roller. When the conveyor belt reciprocates, the cleaning roller evenly applies the release agent to the surface of the conveyor belt through the rubber sleeve to prevent the viscous mixed liquid from adhering to the conveyor belt, which is conducive to the separation of the formed polyimide film from the conveyor belt.

[0025] 3. The present invention provides a scraper unit that can process films of different thicknesses by changing the height of the scraper frame. The organic solvent in the middle of the liquid storage frame enters the cavity through the second liquid inlet pipe. The organic solvent is then accurately sprayed onto the surface of the viscous mixed liquid through the spray hole, which is conducive to the accurate casting of the mixed liquid and the subsequent stretching process. The rotating roller plays a dredging role, preventing the viscous mixed liquid from accumulating and clogging.

[0026] 4. The present invention provides a stretching module. The stretching roller can stretch the polyimide film according to the usage requirements so that the size of the polyimide film meets the usage requirements. The drying rack can evaporate the organic solvent on the surface of the mixed liquid. The negative pressure pipe is connected to the negative pressure fan. Under the action of negative pressure, the evaporated organic solvent contacts the condenser pipe through the ventilation groove. The gaseous organic solvent condenses under the action of water cooling and falls into the collection rack. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described below with reference to the accompanying drawings and examples.

[0028] Figure 1 It is the process flow chart of this application.

[0029] Figure 2 It is a schematic diagram of the three-dimensional structure of this application.

[0030] Figure 3 It is a schematic diagram of the cross-sectional structure of this application.

[0031] Figure 4 It is a schematic diagram of the cross-sectional structure of the cleaning unit of this application.

[0032] Figure 5 It is a schematic diagram of the three-dimensional structure of the scraper unit of the present application.

[0033] Figure 6 It is a schematic diagram of the cross-sectional structure of the casting module of this application.

[0034] Figure 7 It is a schematic diagram of the cross-sectional structure of the scraper unit of the present application.

[0035] Figure 8 It is a schematic diagram of the cross-sectional structure of the stretching module of this application. DETAILED DESCRIPTION

[0036] The following is combined with Figures 1-8 This application is described in further detail.

[0037] The embodiments of the present application disclose a method for preparing a highly dimensionally stable polyimide film, which can accurately achieve the function of preparing and processing the polyimide film.

[0038] A method for preparing a highly dimensionally stable polyimide film comprises the following steps:

[0039] (1) Mixing of raw materials: The raw materials to be processed are evenly filled into the interior of the reaction tank. Under the action of nitrogen, the raw materials are evenly mixed to form a viscous mixed liquid. The mixed liquid is filtered and defoamed under the protection of dry nitrogen;

[0040] (2) Mixed liquid casting processing: The mixed liquid is subjected to a casting and stretching process, wherein the casting and stretching process uses a casting and stretching device, which is used to stretch the mixed liquid into a film;

[0041] (3) Film trimming and rolling: The formed film is trimmed by cutting, and then the cut film is rolled and fixed.

[0042] In the stirring synthesis of polyamic acid raw materials, high molecular weight and stable performance polyimide film can only be obtained when the reaction temperature is low (10-20°C), the reactant concentration is high (15-25%), the raw material purity is high (≥99.5%), the water content in the reaction system is low (≤0.05%), and the molar ratio of the reactants is controlled with high accuracy.

[0043] The above-mentioned casting and stretching device includes a base frame 1, a conveying module 2, a casting module 3 and a stretching module 4. The conveying module 2 is installed on the upper end of the base frame 1, the casting module 3 is installed on the right side of the upper end of the conveying module 2, and the stretching module 4 is installed on the left side of the upper end of the conveying module 2.

[0044] The conveying module 2 includes a connecting frame 21, a conveyor belt 22 and a cleaning unit 23. The connecting frame 21 is symmetrically installed on the upper end of the base frame 1. The width of the left side between the connecting frames 21 is greater than the width of the right side between the connecting frames 21. Conveyor belts 22 are respectively installed on the left and right sides between the connecting frames 21. The width of the conveyor belts 22 is adapted to the spacing between the connecting frames 21. A cleaning unit 23 is installed between the two conveyor belts 22.

[0045] In actual use, the conveying module 2 can convey the viscous mixed liquid so that the polyimide film can be accurately formed. When the width of the conveying module 2 becomes larger, polyimide films of different sizes can be prepared to ensure the processing effect of the polyimide film.

[0046] In order to accurately clean the surface of the conveyor belt 22, a cleaning unit 23 is provided in this embodiment, and the cleaning unit 23 includes a cleaning frame 231 and a guide roller 232. The cleaning frame 231 has a triangular structure, and the upper end surface of the cleaning frame 231 is flush with the conveyor belt 22. The guide rollers 232 are evenly arranged on the upper end surface of the cleaning frame 231, and the outer side surface of the cleaning frame 231 has an arc-shaped structure.

[0047] During actual use, the outer side of the cleaning rack 231 is provided with flexible bristles, which can effectively clean the surface and prevent the viscous mixed liquid from remaining on the surface of the conveyor belt 22, thereby preventing impurities from affecting the preparation effect of the polyimide film surface.

[0048] In order to accurately ensure the separation of the polyimide film from the surface of the conveyor belt 22, in this embodiment, a liquid storage cavity is provided in the middle of the cleaning frame 231, and the interior of the liquid storage cavity is filled with a release agent. The outer side of the cleaning frame 231 is in contact with the end of the conveyor belt 22, and the outer side of the cleaning frame 231 is evenly provided with through grooves connected to the liquid storage cavity. A cleaning roller 233 is installed in the through groove, and a rubber sleeve is provided on the outer side of the cleaning roller 233.

[0049] During actual use, when the conveyor belt 22 reciprocates, the cleaning roller 233 evenly applies the release agent to the surface of the conveyor belt 22 through the rubber sleeve to prevent the viscous mixed liquid from adhering to the conveyor belt 22, which is conducive to the separation of the polyimide film from the conveyor belt 22.

[0050] The casting module 3 includes a liquid storage tank 31, a scraper unit 32 and a first liquid inlet pipe 33. The liquid storage tank 31 is installed on the right side of the upper end of the conveying module 2, and a discharge port is provided on the left side of the liquid storage tank 31. The scraper unit 32 is installed on the outside of the discharge port. The first liquid inlet pipe 33 is installed on the upper end of the liquid storage tank 31, and the first liquid inlet pipe 33 is connected to the stirred mixed liquid.

[0051] During actual use, the mixed raw materials enter the liquid storage tank 31 through the first liquid inlet pipe 33, and then the raw materials are squeezed out through the discharge port on the left side of the liquid storage tank 31. The scraper unit 32 can accurately scrape the mixed liquid flat so that the mixed liquid can be evenly spread on the upper end of the conveying module 2, which is conducive to the accurate preparation of the polyimide film.

[0052] The scraper unit 32 includes a fixed frame 321, an adjusting rod 322, a limiting rod 323, a liquid storage frame 324 and a scraper branch chain 325. The fixed frame 321 is installed on the outside of the liquid storage tank 31. The fixed frame 321 has a U-shaped structure. A threaded seat is installed in the middle of the upper end of the fixed frame 321. The middle of the threaded seat is connected to the adjusting rod 322 by threaded fitting. The lower end of the adjusting rod 322 is connected to the liquid storage frame 324 through a bearing. The liquid storage frame 324 is filled with an organic solvent. Through holes are symmetrically provided on the fixed frame 321. The limiting rod 323 is connected in the through hole by sliding fitting. The lower end of the limiting rod 323 is connected to the liquid storage frame 324. The scraper branch chain 325 is installed at the lower end of the liquid storage frame 324 by screws.

[0053] During actual use, the adjusting rod 322 is rotated, and the adjusting rod 322 can drive the scraper branch chain 325 to move downward through the liquid storage rack 324, thereby adjusting the gap between the scraper branch chain 325 and the conveying module 2, and processing films of different thicknesses.

[0054] In order to prevent the viscous mixed liquid from being blocked, a scraper branch chain 325 is provided in this embodiment, and the scraper branch chain 325 includes a scraper frame 3251, a second liquid inlet pipe 3252 and a rotating roller 3253. The scraper frame 3251 is installed at the lower end of the liquid storage frame 324, and a cavity is provided in the middle of the scraper frame 3251. The second liquid inlet pipe 3252 communicating with the cavity is installed at the upper end of the scraper frame 3251, and the lower end of the liquid storage frame 324 is evenly provided with sealing jacks that cooperate with the second liquid inlet pipe 3252. The lower end surface of the scraper frame 3251 is an arc-shaped surface, and the lower end surface of the scraper frame 3251 is evenly provided with spray holes. The lower end of the scraper frame 3251 is installed with a rotating roller 3253 through a bracket. The rotating roller 3253 is connected to the output shaft of the motor, and the rotating roller 3253 is evenly provided with a toggle piece.

[0055] During actual use, by changing the height of the scraper holder 3251, films of different thicknesses can be processed. The organic solvent in the middle of the liquid storage rack 324 enters the cavity through the second liquid inlet pipe 3252, and the organic solvent is then accurately sprayed onto the surface of the viscous mixed liquid through the spray hole, which is conducive to the accurate casting of the mixed liquid and subsequent stretching processing. The rotating roller 3253 plays a role in clearing and preventing the viscous mixed liquid from accumulating and clogging.

[0056] The toggle piece is detachably arranged on the outside of the rotating roller 3253. The toggle piece is made of hard rubber. When the toggle piece rotates, the toggle piece can effectively drive the viscous mixed liquid to move outward, which is beneficial to the accurate molding of the polyimide film.

[0057] In order to accurately stretch and dry the polyimide film and recover the organic solvent at the same time, a stretching module 4 is provided in this embodiment, and the stretching module 4 includes a mounting frame 41, a stretching roller 42, a negative pressure tube 43, a drying frame 44, a collecting frame 45 and a condensing tube 46. The mounting frame 41 is installed on the upper end of the left side of the conveying module 2, and the stretching roller 42 is symmetrically installed on the lower end of the mounting frame 41 through a bearing. The distance between the stretching roller 42 and the surface of the conveying module 2 is adjustable. A negative pressure tube 43 is installed in the middle of the upper end of the mounting frame 41, and drying frames 44 are evenly installed inside the mounting frame 41. Collecting frames 45 are evenly installed between the upper ends of the drying frames 44. The cross-section of the collecting frames 45 is a V-shaped structure. Ventilation grooves are provided between adjacent collecting frames 45. A condensing tube 46 is provided above the collecting frame 45, and the condensing tube 46 is installed inside the mounting frame 41.

[0058] During actual use, the stretching roller 42 can stretch the polyimide film according to the use requirements so that the size of the polyimide film meets the use requirements. The drying rack 44 can evaporate the organic solvent on the surface of the mixed liquid. The negative pressure pipe 43 is connected to the negative pressure fan. Under the action of negative pressure, the evaporated organic solvent contacts the condensation pipe 46 through the ventilation groove, and the gaseous organic solvent condenses under the action of water cooling and falls into the collection rack 45.

[0059] The embodiments of this specific implementation method are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a highly dimensionally stable polyimide film, characterized in that: The following steps are involved: (1) Stirring and mixing raw materials: The raw materials to be processed are evenly filled into the reaction tank. Under the action of nitrogen, the raw materials are evenly stirred and mixed to form a viscous mixed liquid; (2) Mixed liquid casting processing: The mixed liquid is subjected to a casting and stretching process, wherein the casting and stretching process uses a casting and stretching device, which is used to stretch the mixed liquid into a film; (3) Film trimming and winding: trimming the formed film by cutting, and then winding and fixing the cut film; The above-mentioned casting and stretching device comprises a base frame (1), a conveying module (2), a casting module (3) and a stretching module (4); the conveying module (2) is installed on the upper end of the base frame (1); the casting module (3) is installed on the right side of the upper end of the conveying module (2); and the stretching module (4) is installed on the left side of the upper end of the conveying module (2); The casting module (3) comprises a liquid storage tank (31), a scraper unit (32) and a first liquid inlet pipe (33); the liquid storage tank (31) is installed on the right side of the upper end of the conveying module (2); a discharge port is provided on the left side of the liquid storage tank (31); a scraper unit (32) is installed outside the discharge port; the first liquid inlet pipe (33) is installed on the upper end of the liquid storage tank (31); and the first liquid inlet pipe (33) is connected to the stirred mixed liquid; The scraper unit (32) comprises a fixing frame (321), an adjusting rod (322), a limiting rod (323), a liquid storage frame (324) and a scraper branch chain (325). The fixing frame (321) is installed outside the liquid storage tank (31). The fixing frame (321) is in a U-shaped structure. A threaded seat is installed in the middle of the upper end of the fixing frame (321). The adjusting rod (322) is connected to the middle of the threaded seat by threaded engagement. The lower end of the adjusting rod (322) is connected to the liquid storage frame (324) by a bearing. Through holes are symmetrically provided on the fixing frame (321). The limiting rod (323) is connected to the liquid storage frame (324) by sliding engagement. The lower end of the limiting rod (323) is connected to the liquid storage frame (324). The scraper branch chain (325) is installed at the lower end of the liquid storage frame (324) by screws. The scraper branch chain (325) comprises a scraper frame (3251), a second liquid inlet pipe (3252) and a rotating roller (3253). The scraper frame (3251) is mounted on the lower end of the liquid storage frame (324). A cavity is provided in the middle of the scraper frame (3251). The upper end of the scraper frame (3251) is mounted with a second liquid inlet pipe (3252) in communication with the cavity. The lower end of the liquid storage frame (324) is evenly provided with sealing jacks that cooperate with the second liquid inlet pipe (3252). The lower end surface of the scraper frame (3251) is an arc-shaped surface. Spray holes are evenly provided on the lower end surface of the scraper frame (3251). A rotating roller (3253) is mounted on the lower end of the scraper frame (3251) through a bracket. The rotating roller (3253) is connected to the output shaft of the motor. The rotating roller (3253) is evenly provided with a toggle piece. The organic solvent in the middle of the liquid storage rack (324) enters the cavity through the second liquid inlet pipe (3252), and the organic solvent is then accurately sprayed onto the surface of the viscous mixed liquid through the spray hole, which is beneficial to the accurate casting of the mixed liquid and the subsequent stretching processing. The rotating roller (3253) plays a role in clearing and preventing the viscous mixed liquid from accumulating and clogging.

2. The method for preparing a highly dimensionally stable polyimide film according to claim 1, wherein: The conveying module (2) comprises a connecting frame (21), a conveyor belt (22) and a cleaning unit (23); the connecting frame (21) is symmetrically installed on the upper end of the base frame (1); the width of the left side between the connecting frames (21) is greater than the width of the right side between the connecting frames (21); the conveyor belts (22) are respectively installed on the left and right sides between the connecting frames (21); the width of the conveyor belts (22) is adapted to the spacing between the connecting frames (21); and the cleaning unit (23) is installed between the two conveyor belts (22).

3. The method for preparing a highly dimensionally stable polyimide film according to claim 2, wherein: The cleaning unit (23) comprises a cleaning frame (231) and a guide roller (232); the cleaning frame (231) is triangular in structure; the upper end surface of the cleaning frame (231) is flush with the conveyor belt (22); the guide rollers (232) are evenly arranged on the upper end surface of the cleaning frame (231); and the outer side surface of the cleaning frame (231) is arc-shaped.

4. The method for preparing a highly dimensionally stable polyimide film according to claim 3, wherein: A liquid storage cavity is provided in the middle of the cleaning frame (231), the outer side of the cleaning frame (231) contacts the end of the conveyor belt (22), and through grooves communicating with the liquid storage cavity are evenly provided on the outer side of the cleaning frame (231). A cleaning roller (233) is installed in the through groove, and a rubber sleeve is provided on the outer side of the cleaning roller (233).

5. The method for preparing a highly dimensionally stable polyimide film according to claim 1, wherein: The toggle piece is detachably arranged on the outside of the rotating roller (3253), and the toggle piece is made of hard rubber.

6. The method for preparing a highly dimensionally stable polyimide film according to claim 1, wherein: The stretching module (4) comprises a mounting frame (41), a stretching roller (42), a negative pressure pipe (43), a drying frame (44), a collecting frame (45) and a condensing pipe (46). The mounting frame (41) is mounted on the upper left end of the conveying module (2). The stretching roller (42) is symmetrically mounted on the lower end of the mounting frame (41) through a bearing. The spacing between the stretching roller (42) and the surface of the conveying module (2) is adjustable. The negative pressure pipe (43) is mounted in the middle of the upper end of the mounting frame (41). The drying frames (44) are evenly mounted inside the mounting frame (41). The collecting frames (45) are evenly mounted between the upper ends of the drying frames (44). The cross section of the collecting frames (45) is V-shaped. A ventilation groove is arranged between adjacent collecting frames (45). A condensing pipe (46) is arranged above the collecting frame (45). The condensing pipe (46) is mounted inside the mounting frame (41).

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