CN115418019A - Preparation method of polyimide film for heat conduction graphite - Google Patents
Preparation method of polyimide film for heat conduction graphite Download PDFInfo
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- C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
- C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
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- C08G73/1007—Preparatory processes from tetracarboxylic acids or derivatives and diamines
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- C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
- C08G73/1067—Wholly aromatic polyimides, i.e. having both tetracarboxylic and diamino moieties aromatically bound
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- C08J2379/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
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Abstract
The invention relates to a preparation method of a polyimide film for heat conduction graphite, which comprises the following steps of preparing montmorillonite modified dispersion liquid, preparing polyamide acid resin, preparing a polyimide gel film and preparing the polyimide film, wherein a casting machine is adopted for processing when the polyimide gel film is prepared. The invention can solve the problems that the molecular orientation degree of the PMDA/ODA-based polyimide film is insufficient due to unreasonable selection of resin and filler, small molecular gas is difficult to overflow in the graphitization process to form a foaming effect, a high-quality heat-conducting graphite film is difficult to prepare, in addition, a scraper needs to be manually adjusted when polyimide films with different thicknesses or different widths are produced in the casting process for preparing the graphite film, the precision is poor, the production precision of the polyimide film is influenced, and the like.
Description
Technical Field
The invention relates to the field of polyimide films for heat-conducting graphite, in particular to a preparation method of a polyimide film for heat-conducting graphite.
Background
The traditional heat dissipation materials are metals with high heat conductivity, such as copper, silver and aluminum, but the requirements of microelectronic products cannot be met with the increase of the heat productivity of electronic components. The graphite flake has the characteristics of high heat dissipation efficiency, small occupied space, light weight, uniform heat conduction along two directions and the like, and can uniformly distribute heat on a two-dimensional plane so as to effectively transfer the heat. Therefore, in recent years, it has attracted attention as a heat dissipating member for electronic devices, and has a wide application prospect in the fields of microelectronic packaging and integration.
In the last 70 s, japanese scientists discovered that Polyimide (PI) films could be carbonized and graphitized to obtain highly oriented graphite heat conducting films close to single crystal graphite structures. However, the conventional Polyimide (PI) film is difficult to prepare a stable graphite film, and the prepared graphite film has low thermal conductivity, poor mechanical property and low bending resistance, and is easy to fall off and break in the preparation and use processes. With the expansion of 5G communications, the need for thermal management materials with superior performance is also increasing.
Polyimide has excellent performance, and the preparation of graphite film from polyimide is more and more important. A large number of polyimide fired artificial graphite films are currently used in electronic devices. However, the graphite film prepared from the existing PMDA/ODA type polyimide has unsatisfactory heat conduction and mechanical properties, each property of the polyimide graphite film depends on the polyimide used as a raw material, the polyimide film of the traditional PMDA/ODA system has the characteristics of low foaming rate, low film forming rate and poor heat conduction property in the process of firing the graphite film, the reasons of large amount of literature consultation and experimental demonstration are mainly that the PMDA/ODA based polyimide film has insufficient molecular orientation degree due to unreasonable selection of resin and filler, small molecular gas is difficult to overflow in the graphitization process to form a foaming effect, and the high-quality heat conduction graphite film is difficult to prepare. On the basis, how to adjust the resin structure and the film forming process of polyimide to obtain the artificial graphite film with excellent thermal conductivity and mechanical properties is a topic which needs to be researched.
Disclosure of Invention
Technical problem to be solved
The preparation method of the polyimide film for the heat-conducting graphite can solve the technical problems mentioned above.
(II) technical scheme
In view of the problems of the background art, the present invention provides a method for preparing a polyimide film for thermal conductive graphite, and to achieve the above technical object, the present invention adopts the following technical scheme:
the preparation method of the polyimide film for the heat-conducting graphite comprises the following steps:
(1) Preparing montmorillonite modified dispersion liquid: adding the montmorillonite with different particle sizes subjected to acidizing or amination surface treatment into an NMP (N-methyl pyrrolidone) polar solvent for mixing, and performing ultrasonic dispersion to form uniform montmorillonite modified dispersion liquid;
(2) Preparation of a Polyamic acid resin: adding the montmorillonite modified dispersion liquid obtained in the step (1) into a mixed solvent, continuously stirring, then sequentially adding a diamine monomer and a dianhydride monomer, and carrying out polycondensation reaction to generate polyamide acid resin;
(3) Preparing a polyimide gel film: casting the polyamic acid resin obtained in the step (2) by a casting machine, then heating at high temperature, and obtaining a polyimide gel film after partial imidization;
(4) Preparing a polyimide film: and (4) heating the polyimide gel film obtained in the step (3) at a high temperature, and stretching the film in the transverse and longitudinal directions to obtain the polyimide film.
Preferably, the montmorillonite in the step (1) is M813515 montmorillonite K-10, the particle size of the montmorillonite is 50-100nm, and the addition amount of the montmorillonite is 0.5-1.5% of the mass of the polyimide film.
Preferably, the solid content of the montmorillonite-modified dispersion in the step (1) is 25%.
Preferably, the mixed solvent in the step (2) is a mixed solvent of Dimethylacetamide (DMAC) and N-methylpyrrolidone (NMP), and the mass ratio is 70:30.
preferably, the diamine monomer in step (2) is a combination of 4,4 'diaminodiphenyl ether (ODA) and p-Phenylenediamine (PDA), and the molar ratio of the diamine monomer 4,4' diaminodiphenyl ether (ODA) to the p-Phenylenediamine (PDA) is 85:15.
preferably, the dianhydride monomer in step (2) is a combination of pyromellitic dianhydride (PMDA) and 3,3', 4' -biphenyltetracarboxylic dianhydride (s-BPDA), and the molar ratio of the dianhydride monomer to the 3,3', 4' -biphenyltetracarboxylic dianhydride (s-BPDA) is 10:90.
preferably, the molar ratio of the diamine monomer to the dianhydride monomer in the step (2) is 1.
Preferably, the high-temperature heating treatment in the step (3) is heating at 60 ℃ for 1h, heating at 120 ℃ for 0.5h, and heating at 180 ℃ for 0.5h.
Preferably, in the partial imine in the step (3), the imidization degree is greater than 40%, and the solvent content of the polyimide gel film obtained after imidization is less than 25%.
The preparation of the polyamic acid adhesive film by adopting the casting machine comprises the following steps:
s1, preparation operation: filtering the polyamic acid resin, defoaming the filtered polyamic acid resin, and then pouring the defoamed polyamic acid resin into a liquid storage frame through an infusion tube;
s2, adjusting operation: starting a bidirectional air cylinder control adjusting mechanism to adjust according to the width of the polyimide gel film to be prepared, and synchronously adjusting the width of a discharge pipe to ensure that the discharge width of the discharge pipe corresponds to the prepared polyimide gel film;
s3, placing and conveying: placing a glass plate for bearing polyamide acid resin on a conveying mechanism, driving the glass plate to move from front to back at a constant speed through the conveying mechanism, and limiting the moving glass plate through an adjusting mechanism;
s4, coating and scraping treatment: according to the width of the glass plate and the thickness of the glass plate to be coated with the polyamic acid resin, a scraper mechanism is matched with the opening and closing branched chains, the polyamic acid resin is uniformly coated on the glass plate, and redundant polyamic acid resin is scraped during the movement of the glass plate;
s5, heating treatment: and taking the glass plate coated with the polyamic acid resin out of the conveying mechanism, and then carrying out heating treatment, wherein the polyamic acid resin on the glass plate is partially imidized to obtain the polyimide gel film.
The casting machine comprises a base plate, wherein an adjusting and conveying device is arranged on the base plate, and a coating device is arranged on the adjusting and conveying device;
the adjusting and conveying device comprises a conveying support arranged on the substrate, a conveying mechanism is arranged on the conveying support, adjusting holes are symmetrically formed in the conveying support, a supporting flat plate is arranged on the conveying support, a bidirectional air cylinder is arranged at the lower end of the supporting flat plate, and adjusting mechanisms are symmetrically arranged on the bidirectional air cylinder;
the conveying mechanism comprises conveying rollers arranged on the front side and the rear side of the conveying support through bearings, a conveying belt is arranged between the two conveying rollers, the left side of the conveying roller positioned at the front end of the conveying support is connected with a conveying motor through a coupling, the conveying motor is installed on the conveying support through a motor base, and the upper end face of the supporting flat plate is attached to the conveying belt;
the adjusting mechanism comprises an adjusting rod arranged on the bidirectional cylinder, the adjusting rod is arranged in an adjusting hole in a sliding manner, the conveying support is provided with a moving hole, a moving rod is arranged in the moving hole in a sliding manner, the moving rod is connected with the adjusting rod through a connecting plate, an adjusting execution plate is arranged on the moving rod, and the lower end face of the adjusting execution plate is attached to the conveying belt;
the coating device comprises a liquid storage frame arranged on the conveying support, a filling pipe is arranged at the upper end of the liquid storage frame, a discharging pipe is arranged at the lower end of the liquid storage frame, a scraper mechanism is arranged on the conveying support, and an opening and closing branched chain is arranged in the discharging pipe;
scraper mechanism includes and is in through the bearing setting last rotatory pipe of transfer gantry, evenly be provided with the mounting groove along its circumference on the rotatory pipe, it is provided with the scraper support to slide in the mounting groove, the scraper support with be provided with reset spring between the rotatory pipe, be provided with on the scraper support and lean on the pole, it is located to lean on the pole in the rotatory pipe, be provided with the scraper blade on the scraper support, the chucking groove has been seted up to the left and right sides symmetry of scraper blade, the left end of transfer gantry is provided with control motor through the motor cabinet, control motor's output shaft pass through the shaft coupling with the left end of rotatory pipe links to each other, the right-hand member of rotatory pipe is open structure, just the right-hand member of transfer gantry is provided with the control branch chain.
The control branch chain is including installing the control cylinder of transfer gantry right-hand member, be provided with on the control cylinder and be used for carrying out the extruded control support to the pole that leans on, the control support is located in the swinging tube, just the control support is Z style of calligraphy structure.
The width of the scraper plate positioned in the mounting groove is sequentially increased along the clockwise direction of the rotating pipe.
The left end and the right end of the conveying support are symmetrically provided with shielding grooves, shielding frames used for shielding the discharging pipe are arranged in the shielding grooves in a sliding mode, the shielding frames are connected with the discharging pipe in a sliding mode, and the shielding frames are fixed on the adjusting execution plate.
The opening and closing branched chain comprises an opening and closing plate arranged in the discharging pipe through a pin shaft, an opening and closing hole is formed in the discharging pipe, an opening and closing frame is arranged in the opening and closing hole in a sliding mode, a supporting spring is arranged between the opening and closing frame and the outer wall of the discharging pipe, the opening and closing frame abuts against a cam block, and the cam block is symmetrically arranged on the left side and the right side of the rotating pipe.
(III) advantageous effects
1. Rigid monomers BPDA and PDA are introduced, so that the orientation degree of polyimide molecules can be improved, and foaming is facilitated; and meanwhile, the proportion of the BPDA and the PDA is regulated and controlled, so that the quick low-temperature imidization can be realized, the influence of high-temperature imidization thermal disturbance on the molecular orientation is reduced, and the structural degree of structural selection of polyimide molecules is improved.
2. The introduction of BPDA can improve the carbon residue after graphitization, improve the density of amorphous carbon free radicals, and is more beneficial to the conversion of amorphous carbon to crystalline carbon in the high-temperature graphitization process, thereby improving the quality of the graphitized material.
3. The mixed solvent NMP/DMAC with different boiling points is selected, so that desolvation and imidization in the film forming process are facilitated under a specific proportion, the molecular orientation degree is facilitated to be improved, and the foaming capacity is improved.
4. The foaming agent selects modified montmorillonite which is of a layered porous structure, has a nitrogen fixing function, improves the nitrogen content in amorphous carbon in the graphitization process, is beneficial to the amorphous carbon recrystallization process in graphitization, and improves the graphite quality.
5. The product is used for downstream customers to fire a graphite film, and the graphite film has high thermal conductivity, mechanical ductility, flexibility and the like, and is an ideal heat dissipation material for terminal electronic products.
6. The casting machine of preparation polyamic acid glued membrane design can carry out automated control to the polyimide film of different width and different thickness, can be according to the quick change mode of actual production demand, can improve the efficiency of the polyimide film of different specifications of production, and accommodation range is wide, need not the manual work and adjust the scraper blade according to the polyimide film, the branch chain that opens and shuts and adjustment mechanism that design can adjust coated width in the operation in addition casting machine mutually supports, the time of retrieving polyamic acid resin has been practiced thrift, the rate of utilization of polyamic acid resin has been improved.
Drawings
FIG. 1 is a process flow diagram of a method for preparing a polyimide film for thermally conductive graphite according to the present invention;
FIG. 2 is a schematic structural view of the casting machine of the present invention;
FIG. 3 is a cross-sectional view of the invention of FIG. 2;
FIG. 4 is an enlarged view of a portion of FIG. 3 in accordance with the present invention;
FIG. 5 is an enlarged view of a portion of the invention at B of FIG. 3;
FIG. 6 is a schematic view of the structure between the substrate, the conditioning conveyor and the coating apparatus of the present invention;
FIG. 7 is a cross-sectional view of the conditioning delivery assembly of the present invention;
FIG. 8 is a cross-sectional view of the delivery leg, discharge tube, scraper mechanism and open-close arms of the present invention;
FIG. 9 is a flow chart of the present invention for preparing a polyamic acid film using a casting machine.
Detailed Description
Example 1:
as shown in fig. 1 to 9, the method for preparing a polyimide film for thermal conductive graphite comprises the following steps:
(1) Preparing montmorillonite modified dispersion liquid: adding 50g of acidified montmorillonite into 200g of NMP polar solvent, and mixing, wherein the montmorillonite is M813515 montmorillonite K-10, has particle diameter of 50-100nm and specific surface area of 240M 2 The addition amount of the dispersion liquid is 0.5% -1.5% of the mass of the polyimide film in the step (4), ultrasonic dispersion is carried out for 2 hours, uniform montmorillonite modified dispersion liquid is formed, and the solid content of the montmorillonite modified dispersion liquid is 25%;
(2) Preparation of a polyamic acid resin: under a nitrogen atmosphere, dimethylacetamide (DMAC) and N-methylpyrrolidone (NMP) were added as a mixed solvent in a 500mL reactor at a mass ratio of 70:30, 2.2g of the montmorillonite-modified dispersion obtained in step (1) was taken and added to the mixed solvent, the temperature was set to 25 ℃, then stirring was continued, 39.0g of 4,4' -diaminodiphenyl ether (ODA) and 0.4g of p-Phenylenediamine (PDA) were added as diamine monomers, and stirring was continued for 30min, after confirming the dissolution of the monomers, 5.0g of pyromellitic dianhydride (PMDA) and 60.9g of 3,3', 4' -biphenyltetracarboxylic dianhydride (s-BPDA) were added as dianhydride monomers, and the final amount of addition was adjusted and then added so that the final viscosity became 150000 to 200000 cps. After the addition was completed, stirring was performed for 1 hour while maintaining the temperature to polymerize the polyamic acid solution so that the final viscosity was 180000 cps, and a polyamic acid resin was produced through polycondensation;
(3) Preparing a polyimide gel film: filtering and defoaming the polyimide resin obtained in the step (2), casting by a casting machine, adjusting the thickness of a scraper to be 500 mu m, coating the obtained product on a glass plate by the scraper, heating the obtained product at 60 ℃ for 1h, heating the obtained product at 120 ℃ for 0.5h and heating the obtained product at 180 ℃ for 0.5h, and obtaining a polyimide gel film after partial imidization, wherein the imidization degree is more than 40 percent, and the solvent content of the polyimide gel film obtained after imidization is less than 25 percent;
(4) Preparing a polyimide film: fixing the polyimide gel film obtained in the step (3) on a chopping board to fix four sides, heating at high temperature, heating in an oven at 200 ℃ for 5min, at 350 ℃ for 3min, at 400 ℃ for 3min, and stretching in a transverse direction and a longitudinal direction to reach the thickness of 50um to obtain the polyimide film.
The preparation of the polyamic acid adhesive film by adopting the casting machine comprises the following steps:
s1, preparation operation: filtering the polyamic acid resin, defoaming the filtered polyamic acid resin, and then pouring the defoamed polyamic acid resin into the liquid storage frame 41 through the filling pipe;
s2, adjusting operation: starting the bidirectional air cylinder 24 to control the adjusting mechanism 25 to adjust according to the width of the prepared polyamide acid adhesive film, and synchronously adjusting the width of the discharging pipe 44, so that the discharging width of the discharging pipe 44 corresponds to the prepared polyimide gel film;
s3, placing and conveying: placing a glass plate for bearing the polyamic acid resin on a conveying mechanism 22, driving the glass plate to move from front to back at a constant speed through the conveying mechanism 22, and limiting the moving glass plate by an adjusting mechanism 25;
s4, coating and scraping treatment: according to the width of the glass plate and the thickness of the glass plate to be coated with the polyamide acid resin, a scraper mechanism 45 is matched with the opening and closing branch chain 46, the polyamide acid resin is uniformly coated on the glass plate, and redundant polyamide acid resin is scraped during the movement of the glass plate;
s5, heating treatment: the glass plate coated with the polyamic acid resin is taken out from the transfer mechanism 22 and then subjected to a heat treatment, and the polyamic acid resin on the glass plate is partially imidized to obtain a polyimide gel film.
The casting machine comprises a substrate 1, wherein an adjusting and conveying device 2 is arranged on the substrate 1, and a coating device 4 is arranged on the adjusting and conveying device 2;
inject polyimide acid resin into coating device 4 in, place the glass board in the operation on adjusting conveyor 2, drive the glass board through adjusting conveyor 2 and carry out uniform velocity and remove, coating device 4 evenly paints polyimide acid resin on the glass board, unnecessary polyimide acid resin falls into on adjusting conveyor 2, retrieves unnecessary polyimide acid resin on adjusting conveyor 2 along with adjusting conveyor 2's cyclic motion.
The adjusting and conveying device 2 comprises a conveying support 21 arranged on the substrate 1, a conveying mechanism 22 is arranged on the conveying support 21, adjusting holes are symmetrically formed in the conveying support 21, a supporting flat plate 23 is arranged on the conveying support 21, a bidirectional air cylinder 24 is arranged at the lower end of the supporting flat plate 23, and adjusting mechanisms 25 are symmetrically arranged on the bidirectional air cylinder 24;
the conveying mechanism 22 comprises conveying rollers 221 arranged at the front side and the rear side of the conveying support 21 through bearings, a conveying belt 222 is arranged between the two conveying rollers 221, the left side of the conveying roller 221 positioned at the front end of the conveying support 21 is connected with a conveying motor 223 through a coupling, the conveying motor 223 is installed on the conveying support 21 through a motor base, and the upper end face of the support flat plate 23 is attached to the conveying belt 222;
after the glass plate is placed on the conveying belt 222, the conveying motor 223 is started to drive the conveying roller 221 to rotate, the conveying roller 221 drives the conveying belt 222 to perform circular motion in the rotating process, and the conveying belt 222 drives the glass plate to perform uniform motion from front to back in the circular motion process.
The adjusting mechanism 25 comprises an adjusting rod 251 installed on the bidirectional cylinder 24, the adjusting rod 251 is slidably disposed in the adjusting hole, the conveying support 21 is provided with a moving hole, a moving rod 252 is slidably disposed in the moving hole, the moving rod 252 is connected with the adjusting rod 251 through a connecting plate 253, an adjusting execution plate 254 is disposed on the moving rod 252, and a lower end surface of the adjusting execution plate 254 is attached to the conveying belt 222;
according to the width of a glass plate to be placed on the conveying belt 222, the two-way air cylinder 24 is started, the two-way air cylinder 24 drives the adjusting rods 251 on two sides to perform opposite adjusting operation in the moving process, the adjusting rods 251 drive the adjusting execution plates 254 to perform synchronous movement through mutual matching between the connecting plate 253 and the moving rod 252 in the moving process, the two adjusting execution plates 254 control the distance between the two adjusting execution plates 254 in the adjusting operation, so that the adjusting execution plates 254 can be attached to the end faces of the glass plate, balls are arranged on the adjusting execution plates 254 and attached to the end faces of the glass plate in the operation, the conveying belt 222 is not influenced to drive the glass plate to move while the adjusting execution plates 254 can limit the end faces of the glass plate, and therefore polyimide resin can be uniformly coated on the upper end faces of the glass plate in the operation.
The coating device 4 comprises a liquid storage frame 41 arranged on the conveying support 21, the upper end of the liquid storage frame 41 is provided with a filling pipe, the lower end of the liquid storage frame 41 is provided with a discharging pipe 44, the conveying support 21 is provided with a scraper mechanism 45, and an opening and closing branched chain 46 is arranged in the discharging pipe 44;
the scraper mechanism 45 of design can drive the specification according to the glass board and select the regulation in the operation to can adapt to the polyimide film of different width of production, the branch chain 46 that opens and shuts of design can reduce the polyimide acid resin in the operation and fall into the volume of conveyer belt 222, thereby reduces the waste of material, has saved the time of retrieving polyimide acid resin moreover.
Scraper mechanism 45 includes and is in through the bearing setting rotatory pipe 451 on the transport support 21, evenly be provided with the mounting groove along its circumference on the rotatory pipe 451, it is provided with scraper support 452 to slide in the mounting groove, scraper support 452 with be provided with reset spring between the rotatory pipe 451, be provided with on the scraper support 452 and lean on pole 453, lean on pole 453 to be located in rotatory pipe 451, be provided with scraper blade 454 on the scraper support 452, the chucking groove has been seted up to scraper blade 454's the left and right sides symmetry, the left end of transport support 21 is provided with control motor 455 through the motor cabinet, control motor 455's output shaft pass through the shaft coupling with the left end of rotatory pipe 451 links to each other, the right-hand member of rotatory pipe 451 is open structure, just the right-hand member of transport support 21 is provided with control branch 456.
After the position of the adjusting execution plates 254 is adjusted, the control motor 455 is started to drive the rotating pipe 451 to rotate, the rotating pipe 451 controls the appropriate scraper plate 454 to move between the two adjusting execution plates 254 during the rotation, the width of the scraper plate 454 is equal to the width of the placed glass plate, and then the scraper plate 454 moves downwards by adjusting the distance between the scraper supports 452 through the control branched chain 456, and the distance between the scraper plate 454 and the glass plate is equal to the thickness of the polyimide resin to be coated on the glass plate.
The control branch 456 comprises a control cylinder 4561 installed at the right end of the conveying support 21, a control support 4562 for pressing the abutment rod 453 is arranged on the control cylinder 4561, the control support 4562 is located in the rotating pipe 451, and the control support 4562 is in a Z-shaped structure.
Start control cylinder 4561 and drive control support 4562 and carry out concertina movement in the concrete operation, control support 4562 extrudes abutment bar 453 at the in-process of motion, abutment bar 453 that receives after the extrusion drives scraper support 452 downstream, thereby drive scraper plate 454 through scraper support 452 and carry out height control, not only can assist spacingly to the glass board of different specifications in concrete operation through adopting foretell technical scheme, thereby ensure to produce the polyimide film of different specifications in the operation, in addition can also control the polyimide acid resin thickness that coats on the glass board, can guarantee to produce the size in the actual production operation, the polyimide film of thickness difference, accommodation is wide, need not artifical the regulation, the labour has been practiced thrift, the precision of producing different polyimide film of specification has been improved simultaneously.
The scraper plate 454 width that is located in the mounting groove is followed the clockwise of rotatory pipe 451 is increased gradually in proper order for the glass board to different widths has the scraper plate 454 cooperation operation of corresponding specification, need not artifical the selection and adjusts scraper plate 454, and degree of automation is high, and for artifical the selection or adjust scraper plate 454 and have higher precision, can improve the precision of producing different specification polyimide film moreover.
Shielding grooves are symmetrically formed in the left end and the right end of the conveying support 21, shielding frames 211 used for shielding the discharge pipe 44 are arranged in the shielding grooves in a sliding mode, the shielding frames 211 are connected with the discharge pipe 44 in a sliding mode, and the shielding frames 211 are fixed on the adjusting execution plate 254;
adjusting execution plate 254 and moving shielding frame 211 in-process synchronous motion that carries out position control and carrying out the position and remove, shielding frame 211 can control at the in-process of motion and adjust discharging pipe 44 opening width for discharging pipe 44 discharge opening's width corresponds with the glass board, avoids appearing the direct condition that falls into on the conveyer belt 22 from discharging pipe 44 of polyimide acid resin and appears, can carry out the regulation of adaptability to the glass board of multiple different width through adopting above-mentioned technical scheme in the operation and handle.
The opening and closing branched chain 46 comprises an opening and closing plate 461 arranged in the discharge pipe 44 through a pin shaft, an opening and closing hole is formed in the discharge pipe 44, an opening and closing frame 462 is arranged in the opening and closing hole in a sliding manner, a supporting spring is arranged between the opening and closing frame 462 and the outer wall of the discharge pipe 44, the opening and closing frame 462 abuts against a cam block 463, and the cam blocks 463 are symmetrically arranged at the left side and the right side of the rotating pipe 451;
when polyimide acid resin is required to be coated on a glass plate in operation, the control motor 455 drives the rotary pipe 451 to synchronously control the cam block 463 to adjust, so that the opening and closing frame 462 abuts against the concave position of the cam block 463, the opening and closing plate 461 at the moment is attached to the inner wall of the discharge pipe 44 under the action of the supporting spring, the discharge pipe 44 is in an open state under the state, the polyimide acid resin can be smoothly discharged from the discharge pipe 44 and coated on the glass plate, when the polyimide acid resin is not required to be coated on the glass plate, the control motor 455 drives the rotary pipe 451 to synchronously control the cam block 463 to adjust, so that the opening and closing frame 462 abuts against the convex position of the cam block 463, the opening and closing plate 461 at the moment is attached to the inner wall of the other end of the discharge pipe 44 under the action of the opening and closing frame 462, the discharge pipe 44 at the moment is in a closed state, and the polyimide acid resin cannot be discharged.
Example 2:
as shown in fig. 1 to 9, the method for preparing a polyimide film for thermal conductive graphite comprises the following steps:
the procedure and method were the same as in example 1 except that 4.4g of the montmorillonite modified dispersion liquid was added in the step (2).
Comparative example 1:
the preparation method of the polyimide film for the heat-conducting graphite comprises the following steps:
the procedure of step (1) was followed in the same manner as in example 1.
Comparative example 2:
the preparation method of the polyimide film for the heat-conducting graphite comprises the following steps:
the procedure of example 1 was repeated, except that 39.8g of 4,4' -diaminodiphenyl ether (ODA) was added as a diamine monomer in step (2), and after stirring for 30min to confirm dissolution of the monomer, 43.4g of pyromellitic dianhydride (PMDA) was added as a dianhydride monomer.
The degree of molecular orientation was evaluated according to the birefringence value of the anisotropic material, birefringence: the birefringence of the polyimide film was measured using a refractive index and film thickness measuring system (model number: 2010prism coupler) manufactured by Metricon (in the measurement, the refractive index was measured in TE mode and TM mode using a light source having a wavelength of 594nm in an environment of 23 ℃, and the measured "(value of refractive index in TE mode) - (value of refractive index in TM mode)" was used as the birefringence).
Thermal diffusivity: the measuring instrument is a diffusion method heat conduction instrument LFA467 produced by Germany Chinesemeter; the testing temperature is room temperature; the test mode is In-Plane; the light spot is 14mm; the protective gas is nitrogen.
Preparing an artificial graphite film: the method for preparing the artificial graphite film is not limited, and a conventional method is adopted. The polyimide films obtained in the examples and the comparative example 1 were used as raw materials to obtain corresponding artificial graphite films.
Claims (9)
1. The preparation method of the polyimide film for the heat-conducting graphite comprises the following steps:
(1) Preparing montmorillonite modified dispersion liquid: adding montmorillonite with different particle sizes subjected to acidizing or amination surface treatment into an NMP polar solvent for mixing, and performing ultrasonic dispersion to form uniform montmorillonite modified dispersion liquid;
(2) Preparing polyimide resin: adding the montmorillonite modified dispersion liquid obtained in the step (1) into a mixed solvent, continuously stirring, then sequentially adding a diamine monomer and a dianhydride monomer, and carrying out polycondensation reaction to generate polyimide resin;
(3) Preparing a polyamic acid adhesive film: carrying out tape casting treatment on the polyimide resin obtained in the step (2) through a tape casting machine, and obtaining a polyimide gel film after partial imidization;
(4) Preparing a polyimide composite film: heating the polyimide gel film obtained in the step (3) at a high temperature, and stretching the polyimide gel film in a transverse and longitudinal direction to obtain a polyimide composite film;
the casting machine comprises a base plate (1), wherein an adjusting and conveying device (2) is arranged on the base plate (1), and coating devices (4) are sequentially arranged on the adjusting and conveying device (2) from front to back;
the adjusting and conveying device (2) comprises a conveying support (21) arranged on the substrate (1), a conveying mechanism (22) is arranged on the conveying support (21), adjusting holes are symmetrically formed in the conveying support (21), a supporting flat plate (23) is arranged on the conveying support (21), a bidirectional air cylinder (24) is arranged at the lower end of the supporting flat plate (23), and adjusting mechanisms (25) are symmetrically arranged on the bidirectional air cylinder (24);
the coating device (4) comprises a liquid storage frame (41) arranged on the conveying support (21), a filling pipe is arranged at the upper end of the liquid storage frame (41), a discharging pipe (44) is arranged at the lower end of the liquid storage frame (41), a scraper mechanism (45) is arranged on the conveying support (21), and an opening and closing branched chain (46) is arranged in the discharging pipe (44);
the preparation method of the polyimide gel film by adopting the casting machine comprises the following steps:
s1, preparation operation: filtering the polyamic acid resin, defoaming the filtered polyamic acid resin, and then pouring the defoamed polyamic acid resin into a liquid storage frame (41) through an infusion tube;
s2, adjusting operation: starting a bidirectional cylinder (24) to control an adjusting mechanism (25) to adjust according to the width of the prepared polyamic acid adhesive film, and synchronously adjusting the width of a discharge pipe (44) to enable the discharge width of the discharge pipe (44) to correspond to the prepared polyamic acid adhesive film;
s3, placing and conveying: the glass plate for bearing the polyamic acid resin is placed on a conveying mechanism (22), the conveying mechanism (22) drives the glass plate to move from front to back at a constant speed, and an adjusting mechanism (25) limits the moving glass plate;
s4, coating and scraping treatment: according to the width of the glass plate and the thickness of the glass plate to be coated with the polyamic acid resin, a scraper mechanism (45) is matched with the opening and closing branch chain (46), the polyamic acid resin is uniformly coated on the glass plate, and redundant polyamic acid resin is scraped during the movement of the glass plate;
s5, heating treatment: and taking the glass plate coated with the polyamic acid resin out of the conveying mechanism (22), and then carrying out heating treatment, wherein the polyamic acid resin on the glass plate is partially imidized to obtain the polyimide gel film.
2. The method for preparing the polyimide film for thermally conductive graphite according to claim 1, wherein the montmorillonite in the step (1) is M813515 montmorillonite K-10, and the particle size of the montmorillonite is 50-100nm.
3. The method for preparing a polyimide film for thermally conductive graphite according to claim 1, wherein the solid content of the montmorillonite modified dispersion liquid in the step (1) is 25%.
4. The method for preparing a polyimide film for thermally conductive graphite according to claim 1, wherein the mixed solvent in the step (2) is a mixed solvent of Dimethylacetamide (DMAC) and N-methylpyrrolidone (NMP) in a mass ratio of 70.
5. The method for preparing a polyimide film for thermally conductive graphite according to claim 1, wherein the diamine monomer in the step (2) is a combination of 4,4 'diaminodiphenyl ether (ODA) and p-Phenylenediamine (PDA), and the molar ratio of the diamine monomer 4,4' diaminodiphenyl ether (ODA) and p-Phenylenediamine (PDA) is 85.
6. The method of preparing a polyimide film for thermally conductive graphite according to claim 1, wherein the dianhydride monomer in step (2) is a combination of pyromellitic dianhydride (PMDA) and 3,3', 4' -biphenyltetracarboxylic dianhydride (s-BPDA), and the molar ratio of the dianhydride monomers pyromellitic dianhydride (PMDA) and 3,3', 4' -biphenyltetracarboxylic dianhydride (s-BPDA) is 10.
7. The method for preparing a polyimide film for thermally conductive graphite according to claim 1, wherein the molar ratio of diamine monomer to dianhydride monomer in step (2) is 1.
8. The method for preparing a polyimide film for thermally conductive graphite according to claim 1, wherein the high-temperature heating treatment in the step (3) is heating at 60 ℃ for 1h, heating at 120 ℃ for 0.5h, and heating at 180 ℃ for 0.5h.
9. The method for preparing a polyimide film for thermally conductive graphite according to claim 1, wherein the imidization degree of the partial imine in the step (3) is greater than 40%, and the solvent content of the polyamic acid film obtained after imidization is less than 25%.
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| CN111793206A (en) * | 2020-06-09 | 2020-10-20 | 中天电子材料有限公司 | Preparation method of polyimide film and polyimide film |
| CN112429723A (en) * | 2020-12-01 | 2021-03-02 | 江苏星途新材料科技有限公司 | Method for preparing heat-conducting film based on graphene oxide slurry |
| CN112851982A (en) * | 2020-12-29 | 2021-05-28 | 南京精工新材料有限公司 | Polyimide film and preparation method thereof |
| CN113717524A (en) * | 2021-08-31 | 2021-11-30 | 安徽国风塑业股份有限公司 | Polyimide film for preparing graphite film and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106832923A (en) * | 2016-12-16 | 2017-06-13 | 深圳瑞华泰薄膜科技有限公司 | A kind of Kapton for preparing electrographite film and preparation method thereof |
| CN108571179A (en) * | 2018-05-04 | 2018-09-25 | 潘岳燕 | A kind of building structure strengthening construction equipment |
| CN111793206A (en) * | 2020-06-09 | 2020-10-20 | 中天电子材料有限公司 | Preparation method of polyimide film and polyimide film |
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