CN115974067A - High-thermal-conductivity graphite film of pyridine ring modified polyimide and preparation method thereof - Google Patents
High-thermal-conductivity graphite film of pyridine ring modified polyimide and preparation method thereof Download PDFInfo
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- CN115974067A CN115974067A CN202310041326.8A CN202310041326A CN115974067A CN 115974067 A CN115974067 A CN 115974067A CN 202310041326 A CN202310041326 A CN 202310041326A CN 115974067 A CN115974067 A CN 115974067A
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Abstract
The invention discloses a high-thermal-conductivity graphite film of pyridine ring modified polyimide and a preparation method thereof, belonging to the technical field of graphite film preparation. The high-thermal-conductivity graphite film of the pyridine ring modified polyimide is prepared from diamine and dianhydride; the diamine contains all or part or no pyridine structure, the dianhydride contains all or part or no pyridine structure, and at least one raw material contains a pyridine structure. According to the invention, an appropriate amount of pyridine structure is introduced into a PI main chain to form intrinsic PI resin, the pyridine structure has an autocatalysis effect, a planar PI framework is favorably formed, a graphite film is further induced to form a layer structure with orderly and regular structure and high crystallinity, and the heat conductivity coefficient of the graphite film is improved; meanwhile, the temperature for carbonization and graphitization can be reduced, thereby being beneficial to reducing energy consumption and saving energy.
Description
Technical Field
The invention relates to the technical field of graphite film preparation, in particular to a high-thermal-conductivity graphite film of pyridine ring modified polyimide and a preparation method thereof.
Background
In recent years, as electronic devices have been miniaturized and lightened, high thermal conductive graphite film materials have attracted much attention. The graphite films commercialized at present are mainly formed by rolling expanded graphite and high-temperature pyrolysis of polymer films. The graphite film formed by high-temperature pyrolysis of the polymer film has higher thermal conductivity, crystallinity and orientation than the former.
The macromolecules used for preparing the graphite film mainly comprise epoxy resin, phenolic resin, high-crystallinity polyethylene, polyacrylic acid, polyurethane and the like, but the materials are generally difficult to graphitize, low in yield and high in brittleness. The graphitized structure prepared from Polyimide (PI) with aromatic heterocyclic structure has high strength and high carbonization degree, and has attracted extensive attention and developed rapidly in the last 60 th century.
The preparation of the high-performance graphite film by the PI film comprises two processes: carbonization and graphitization. The carbonization is carried out under reduced pressure or under nitrogen (N) 2 ) Preheating the PI film at 800-1500 ℃ in the atmosphere, and applying appropriate pressure to the PI film when heating to avoid wrinkling of the film. The graphitization is carried out under the protection of reduced pressure or inert gas (argon, helium, etc.), and the graphitization temperature is 1800-3000 ℃. Research shows that the performance of the PI-based graphite film can be effectively improved by selecting a PI precursor with a rigid molecular chain and a smoother skeleton structure, or performing appropriate stretching treatment and reasonable heat treatment on the PI precursor.
M. inagaki et al will find that the more oxygen content in the PI structure, the smaller the diameter of the primarily formed crystallites, the lower the graphitization ability, and the higher the graphitization degree with the increase of the temperature rise rate.
Y.Hishiyama et al have studied the graphitization change of the carbon film prepared from the PI base film at 1800-3200 ℃, and have found that the graphite structure gradually tends to be ordered along with the temperature rise.
V.e. smirnova et al show that the ordered crystal structure of the PAA film plays a major role in the formation of highly graphitized films during carbonization-graphitization. Biaxial pre-stretching at the PAA stage can improve the graphite crystallinity and graphitization degree of the film. However, the PI film after stretching orientation has the problems of large shrinkage rate, low surface flatness, easy cracking and the like in the graphitization process, and the large-scale application and popularization of the technology are limited.
Research shows that certain inorganic substances such as iron, nickel and boron compounds, silicon carbide, graphene oxide and the like have catalytic effect on the PI graphitization process. The addition of these substances in the PI preparation stage is beneficial to graphitization catalysis and graphitization degree improvement, and after graphitization, the antistatic adsorption effect is achieved, but at the same time, the thermal diffusion characteristic after graphitization is reduced.
Disclosure of Invention
The invention aims to provide a high-thermal-conductivity graphite film of pyridine ring modified polyimide and a preparation method thereof. An appropriate amount of pyridine structures are introduced into a PI main chain to form intrinsic PI resin, the pyridine structures have an autocatalysis effect, a planar PI framework is favorably formed, a graphite film is further induced to form a layer structure which is orderly and regular and has high crystallinity, and the heat conductivity coefficient of the graphite film is improved; meanwhile, the temperature for carbonization and graphitization can be reduced, thereby being beneficial to reducing energy consumption and saving energy.
In order to achieve the purpose, the invention provides the following technical scheme:
the invention adopts one of the technical schemes: the high-thermal-conductivity graphite film of pyridine ring modified polyimide is prepared from diamine and dianhydride; the diamine contains all or part or no pyridine structure, the dianhydride contains all or part or no pyridine structure, and at least one raw material contains a pyridine structure.
Preferably, the diamine containing a pyridine structure includes: one or more of 1, 4-bis (5-amino-3-pyridyl) benzene, 1, 4-bis (6-amino-4-pyridyl) benzene, 1, 4-bis (5-amino-2-pyridyl) benzene, 1, 4-bis (4-amino-2-pyridyl) benzene, 6 '-diamino-3, 3' -bipyridine, 5 '-diamino-2, 2' -bipyridine, 2, 5-diaminopyridine and 2, 6-diaminopyridine.
Preferably, the dianhydride containing a pyridine structure comprises: 2, 6-bis (3, 4-dicarboxyphenyl) pyridine dianhydride and/or 3, 5-bis (3, 4-dicarboxyphenyl) pyridine dianhydride.
The structural formulas of the diamine containing the pyridine structure and the dianhydride containing the pyridine structure are as follows:
1, 4-bis (5-amino-3-pyridyl) benzene
1, 4-bis (6-amino-3-pyridyl) benzene
1, 4-bis (6-amino-4-pyridyl) benzene
1, 4-bis (5-amino-2-pyridyl) benzene
1, 4-bis (4-amino-2-pyridyl) benzene
6,6 '-diamino-3, 3' -bipyridine
5,5 '-diamino-2, 2' -bipyridine
2, 5-diaminopyridine
2, 6-diaminopyridine
2, 6-bis (3, 4-dicarboxyphenyl) pyridine dianhydride
3, 5-bis (3, 4-dicarboxyphenyl) pyridine dianhydride preferably, the diamine and dianhydride are present in a 1.
The second technical scheme of the invention is as follows: the preparation method of the high-thermal-conductivity graphite film of the pyridine ring modified polyimide comprises the following steps:
(1) Adding diamine and dianhydride into a solvent, and reacting in an inert atmosphere to obtain a polyamic acid (PAA) solution with a main chain containing a pyridine structure;
(2) Carrying out tape casting on the polyamic acid solution to form a film, and heating and imidizing to obtain a polyimide film;
(3) Hot-pressing and carbonizing the polyimide film to prepare a carbonized film;
(4) Graphitizing the carbonized film to obtain the high-thermal-conductivity graphite film of pyridine ring modified polyimide.
Preferably, the reaction time in step (1) is 12 to 24 hours.
Preferably, the heating temperature in the step (2) is 260-300 ℃ and the time is 60-80 min.
Preferably, the hot press carbonization process in the step (3) comprises: and (3) preserving the heat of the polyimide film for 1h at the temperature of 300-350 ℃ and the pressure of 40MPa under the condition that the vacuum degree is less than or equal to-50 KPa, and preserving the heat for 1h at the temperature of 1250-1300 ℃ and the pressure of 60 MPa.
Preferably, the graphitization in the step (4) is carried out in an inert atmosphere, and the graphitization temperature is 2600-2700 ℃ and the time is 1.5-2 h.
More preferably, the temperature increase rate during graphitization is 3 deg.C/min.
The invention has the following beneficial technical effects:
the PI-based graphite film provided by the invention can form a planar PI framework without adding any auxiliary agent or catalyst during preparation, and can induce the graphite film to form a layer structure with orderly and regular structure and high crystallinity, so that the heat conductivity coefficient of the graphite film is improved, the temperature of the whole process flow is reduced, and the energy consumption is reduced.
Drawings
Fig. 1 is a macroscopic view of a PI-based graphite film prepared in example 1 of the present invention.
Fig. 2 is a macroscopic view of a PI-based graphite film prepared in example 2 of the present invention.
Fig. 3 is a macroscopic view of a PI-based graphite film prepared in example 3 of the present invention.
Fig. 4 is a macroscopic view of the PI-based graphite film prepared in comparative example 1 of the present invention.
Detailed Description
Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every intervening value, to the extent any stated or intervening value in a stated range, and every other stated or intervening value in that stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention.
As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.
Example 1
(1) Adding 11.88g (0.11 mol) of p-phenylenediamine and 1.09g (0.01 mol) of 2, 5-diaminopyridine into a 250ml three-neck flask with a magnetic rotor at room temperature, pouring 156g of dimethylacetamide, stirring until dissolving, and adding 26.16g (0.12 mol) of pyromellitic dianhydride and N in 4 portions 2 Stirring for 24 hours at room temperature under protection to obtain a viscous PAA solution, wherein the solid content is 20wt%, and the viscosity is 115 Pa.s;
(2) Standing and defoaming the PAA liquid obtained in the step (1), uniformly coating the surface of glass to form a film, placing the film in an air-blast drying oven at 130 ℃ for 30min, and carefully uncovering the film, wherein the solvent content of the film is about 24wt%;
(3) Fixing the film obtained in the step (2), performing biaxial tension, placing the film in a forced air drying oven at 300 ℃ for 60min, and cooling to room temperature to obtain a PI film;
(4) Placing the PI film prepared in the step (3) in a hot pressing furnace, vacuumizing to less than or equal to-50 KPa, heating to 350 ℃ at the speed of 1 ℃/min to carry out hot pressing on the PI film, keeping the pressure at 40MPa, carrying out heat preservation for 1h, then unloading pressure, heating to 1300 ℃ at the speed of 2 ℃/min, carrying out hot pressing carbonization, keeping the pressure at 60MPa, keeping the temperature for 1h, cooling to a greenhouse, and unloading pressure to obtain a carbonized film;
(5) And (3) placing the carbonized film prepared in the step (4) in a graphitization furnace, introducing Ar gas to replace air, keeping the normal pressure, heating to 2700 ℃ at the speed of 3 ℃/min, preserving the temperature for 2 hours, and cooling to room temperature to obtain the PI-based graphite film, wherein the appearance of the PI-based graphite film is shown in figure 1.
Example 2
(1) 11.88g (0.11 mol) of p-phenylenediamine and 2.62g (0.01 mol) of 1, 4-bis (6-amino-3-pyridyl) benzene were charged into a 250ml three-necked flask equipped with a magnetic rotor at room temperature, 168g of dimethylacetamide was added thereto and stirred to be dissolved, and 23.98g (0.11 mol) of pyromellitic dianhydride and 3.71g (0.01 mol) of a mixed dianhydride consisting of 2, 6-bis (3, 4-dicarboxyphenyl) pyridine dianhydride, N, were added in 4 portions 2 Stirring for 24 hours at room temperature under protection to obtain a viscous PAA solution, wherein the solid content is 19wt%, and the viscosity is 107Pa & s;
(2) Standing and defoaming the PAA liquid obtained in the step (1), uniformly coating the surface of glass to form a film, placing the film in an air-blast drying oven at 120 ℃ for 30min, and carefully uncovering the film, wherein the solvent content of the film is about 31wt%;
(3) Fixing the film obtained in the step (2), performing biaxial tension, placing the film in a forced air drying oven at 280 ℃ for 80min, and cooling to room temperature to obtain a PI film;
(4) Placing the PI film prepared in the step (3) in a hot pressing furnace, vacuumizing to less than or equal to-50 KPa, heating to 320 ℃ at 1 ℃/min to carry out hot pressing on the PI film, keeping the pressure at 40MPa, carrying out heat preservation for 1h, then unloading pressure, heating to 1280 ℃ at 2 ℃/min, carrying out hot pressing carbonization, keeping the pressure at 60MPa, keeping the temperature for 1h, cooling to a greenhouse, and unloading pressure to obtain a carbonized film;
(5) And (3) placing the carbonized film prepared in the step (4) in a graphitization furnace, introducing Ar gas to replace air, keeping the normal pressure, heating to 2700 ℃ at the speed of 3 ℃/min, preserving the heat for 1.5h, and cooling to room temperature to obtain the PI-based graphite film, wherein the appearance of the PI-based graphite film is shown in figure 2.
Example 3
(1) 5.99g (0.055 mol) of 2, 6-diaminopyridine and 0.93g (0.005 mol) of 6,6 '-diamino-3, 3' -bipyridine were charged into a 250ml three-necked flask equipped with a magnetic rotor at room temperature, 98g of dimethylacetamide was added and stirred until dissolved, and 10.90g (0.05 mol) of pyromellitic dianhydride and 3.71g (0.01 mol) of 3, 5-bis (3, 4-dicarboxyphenyl) pyridine dianhydride, mixed dianhydride, N, were added in 4 portions 2 Stirring for 24h at room temperature under protection to obtain a viscous PAA solution with the solid content of 18wt% and the viscosity of 106 Pa.s;
(2) Standing and defoaming the PAA liquid obtained in the step (1), uniformly coating the surface of glass to form a film, placing the film in an air-blast drying oven at 120 ℃ for 30min, and carefully uncovering the film, wherein the solvent content of the film is about 33wt%;
(3) Fixing the film obtained in the step (2), performing biaxial tension, placing the film in a forced air drying oven at 280 ℃ for 60min, and cooling to room temperature to obtain a PI film;
(4) Placing the PI film prepared in the step (3) in a hot pressing furnace, vacuumizing to less than or equal to-50 KPa, heating to 300 ℃ at the speed of 2 ℃/min, carrying out hot pressing on the PI film, keeping the pressure at 40MPa, carrying out heat preservation for 1h, then unloading pressure, heating to 1250 ℃ at the speed of 2 ℃/min, carrying out hot pressing carbonization, keeping the pressure at 60MPa, keeping the temperature for 1h, cooling to a greenhouse, and unloading pressure to obtain a carbonized film;
(5) And (5) placing the carbonized film prepared in the step (4) in a graphitizing furnace, introducing Ar gas to replace air, keeping the normal pressure, heating to 2670 ℃ at the speed of 3 ℃/min, preserving the heat for 2 hours, and cooling to room temperature to obtain the PI-based graphite film, wherein the appearance of the PI-based graphite film is shown in figure 3.
Comparative example 1
The only difference compared to example 1 is that 2, 5-diaminopyridine was replaced with an equimolar amount of p-phenylenediamine. The appearance of the prepared PI-based graphite film is shown in fig. 4.
The properties of the PI-based graphite films prepared in examples 1 to 3 and comparative example 1 were measured, and the measurement results are shown in table 1.
TABLE 1 Properties of PI-based graphite films prepared from the respective groups
The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.
Claims (9)
1. A high-thermal-conductivity graphite film of pyridine ring modified polyimide is characterized by being prepared from diamine and dianhydride; the diamine contains all or part or no pyridine structure, the dianhydride contains all or part or no pyridine structure, and at least one raw material contains a pyridine structure.
2. The highly thermally conductive graphite film of pyridine ring-modified polyimide according to claim 1, wherein the diamine containing a pyridine structure comprises: one or more of 1, 4-bis (5-amino-3-pyridyl) benzene, 1, 4-bis (6-amino-4-pyridyl) benzene, 1, 4-bis (5-amino-2-pyridyl) benzene, 1, 4-bis (4-amino-2-pyridyl) benzene, 6 '-diamino-3, 3' -bipyridine, 5 '-diamino-2, 2' -bipyridine, 2, 5-diaminopyridine and 2, 6-diaminopyridine.
3. The high thermal conductivity graphite film of pyridine ring modified polyimide according to claim 1, wherein dianhydride containing pyridine structure comprises: 2, 6-bis (3, 4-dicarboxyphenyl) pyridine dianhydride and/or 3, 5-bis (3, 4-dicarboxyphenyl) pyridine dianhydride.
4. The highly thermally conductive graphite film of pyridine ring modified polyimide according to claim 1, characterized in that the molar ratio of diamine and dianhydride is 1.
5. A preparation method of the high-thermal-conductivity graphite film of pyridine ring modified polyimide according to any one of claims 1 to 4, characterized by comprising the following steps:
(1) Adding the diamine and the dianhydride into a solvent, and reacting in an inert atmosphere to obtain a polyamic acid solution with a main chain containing a pyridine structure;
(2) Carrying out tape casting on the polyamic acid solution to form a film, and heating and imidizing to obtain a polyimide film;
(3) Hot-pressing and carbonizing the polyimide film to obtain a carbonized film;
(4) Graphitizing the carbonized film to obtain the high-thermal-conductivity graphite film of pyridine ring modified polyimide.
6. The method according to claim 5, wherein the reaction time in the step (1) is 12 to 24 hours.
7. The method according to claim 5, wherein the heating in the step (2) is carried out at a temperature of 260 to 300 ℃ for 60 to 80min.
8. The production method according to claim 5, wherein the hot press carbonization in the step (3) includes: and (3) preserving the heat of the polyimide film for 1h at the temperature of 300-350 ℃ and the pressure of 40MPa under the condition that the vacuum degree is less than or equal to-50 KPa, and preserving the heat for 1h at the temperature of 1250-1300 ℃ and the pressure of 60 MPa.
9. The method according to claim 5, wherein the graphitization in the step (4) is performed under an inert atmosphere at a temperature of 2600-2700 ℃ for 1.5-2 hours.
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