CN115353392A - Preparation method of polyimide-based graphite film with high thermal conductivity - Google Patents
Preparation method of polyimide-based graphite film with high thermal conductivity Download PDFInfo
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- CN115353392A CN115353392A CN202210795195.8A CN202210795195A CN115353392A CN 115353392 A CN115353392 A CN 115353392A CN 202210795195 A CN202210795195 A CN 202210795195A CN 115353392 A CN115353392 A CN 115353392A
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- C04B35/52—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbon, e.g. graphite
- C04B35/524—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbon, e.g. graphite obtained from polymer precursors, e.g. glass-like carbon material
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Abstract
The invention discloses a preparation method of a polyimide-based graphite film with high thermal conductivity, which comprises the following steps: the method adopts a chemical imine method for pre-imidization, and then prepares the polyimide by a low-temperature chemical method. And then the graphite film is prepared through two stages of carbonization and graphitization. The method has the advantages of simple process operation, no need of high-temperature imidization in the preparation process of the polyimide, strong practicability and energy conservation. And the prepared heat conducting film has high heat conductivity coefficient, is easy to realize industrial production and has industrial prospect. The polyimide film prepared by the method is completely imidized and can be used for preparing a graphite film by high-temperature graphitization. Compared with the traditional polyimide film, the polyimide film is more suitable for being used as a base film for preparing a graphite film, improves the graphitization rate and reduces the lattice defect, and is a polyimide-based graphite film preparation method with a novel process.
Description
Technical Field
The invention relates to a preparation method of a graphite film material, in particular to a preparation method of a polyimide-based graphite film with high thermal conductivity.
Background
Polyimide is used as a functional polymer material with good comprehensive performance, has the characteristics of heat resistance, low temperature resistance, radiation resistance, flame retardance and no toxicity, and has excellent mechanical performance, stable size, stable chemical performance and biological stability. Due to the special structure and high carbon content of polyimide, polyimide is also used as an excellent carbon source material to prepare a graphite film material. Compared with other preparation methods, such as a vapor deposition method and a redox graphene method, the polyimide-based thermal treatment method for preparing the graphite film is simple in process, and has wide application space in the aspects of high-thermal-conductivity graphite film and the like.
Disclosure of Invention
The invention aims to provide a preparation method of a polyimide-based graphite film with high thermal conductivity, which has the advantages of simple and easy operation preparation process and high production efficiency
In order to achieve the purpose, the invention adopts the following scheme:
a preparation method of a polyimide-based graphite film with high thermal conductivity is characterized by comprising the following steps:
s1, pre-imidizing by adopting a chemical imine method, adding diamine and dianhydride into a solvent in a reaction kettle, and reacting to generate polyamic acid;
s2, then adding a catalyst mixed solution, and quickly performing tape casting film formation after reaction to prevent the solvent in the reaction kettle from gelling, wherein the temperature in the tape casting process is lower than that required by the common thermoimine method for preparation;
and S3, finally, preparing the graphite film with high heat conductivity after carbonization and graphitization.
Preferably, the catalyst used in the chemical imine method is a mixed solution of pyridine and a dehydrating agent, wherein the catalyst is 2.5-4.0wt% of the mass fraction of the polyamic acid, and the molar ratio of the dehydrating agent to the polyamic acid is 1-3:1.
preferably, the dehydrating agent is propionic anhydride or acetic anhydride.
Preferably, the heating temperature during casting is 200 to 250 ℃.
Preferably, the sum of the mass of dianhydride and diamine is from 15% to 20% of the mass of the solvent.
Preferably, the diamine comprises one or more of 4' 4-diaminodiphenyl ether, diaminobenzophenone or derivatives thereof, diaminodiphenyl sulfone or derivatives thereof and p-phenylenediamine.
Preferably, the dianhydride comprises one or more of pyromellitic dianhydride, biphenyl tetracarboxylic dianhydride, diphenylmethane dianhydride compounds, ketone-containing carbonyl dianhydride compounds and diphenyl ether dianhydride, and the solvent is dimethylacetamide and dimethylformamide.
In summary, compared with the prior art, the invention has the beneficial effects that:
polyimide is used as a functional polymer material with good comprehensive performance, has the characteristics of heat resistance, low temperature resistance, radiation resistance, flame retardance and no toxicity, and has excellent mechanical performance, stable size, stable chemical performance and biological stability. Due to the special structure of polyimide and the high carbon content close to 69%, polyimide is also used as an excellent carbon source material to prepare a graphite film material. The graphite film has the advantages of light specific gravity, high heat conduction, small density, cutting and the like, has wide application space in the market of electronic products, and has bright development prospect in the future. Compared with other preparation methods, such as a vapor deposition method with strict experimental conditions and only capable of being prepared in a laboratory temporarily and a redox graphene method for destroying an electronic structure in a graphite film, the polyimide-based heat treatment method for preparing the graphite film has a simple process and does not generate a large amount of waste liquid. Compared with the graphite film prepared by the expansion-compression casting graphite method and applied to the low-end field (700W/m.K), the graphite film prepared by the polyimide-based heat treatment method has excellent heat conductivity which can be improved by 2-3 times.
Drawings
Fig. 1 is an optical diagram of (a) a PI-based film and (b) a graphite film in the present invention.
FIG. 2 is a FITR chart of all PI films of the present invention.
FIG. 3 is (a) XRD and (b) Raman test charts of the PI-based graphite film of the present invention.
Fig. 4 is the in-plane thermal conductivity of all graphite films in 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 rather 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 smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a 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.
Example 1
First, ODA was added to a beaker containing DMAc and stirred at 350r/min until the ODA was completely dissolved. Thereafter, PMDA was slowly added and the solution was stirred at room temperature for 3 to 4 hours to obtain a 18wt% PAA solution. Secondly, different dosages of pyridine and propionic anhydride are mixed to prepare a catalyst mixed solution. Wherein, the pyridine accounts for 2.5 to 4.0 weight percent of the PAA, and n (propionic anhydride) /n (PAA) 1, = 3. Then, the catalyst mixture was poured into the PAA solution quickly and reacted at room temperature for 5 minutes. Finally, the mixed solution was coated on clean glass and placed in an oven at 90 ℃ for 30min to volatilize the solvent, and then a solid PAA film was obtained. And (3) taking off the solid PAA film from the quartz glass, fixing the film through a self-made frame, placing the film in a drying oven at 200 ℃ for heat treatment for 10min, taking out the film, and cooling the film to room temperature to obtain the PI film prepared by the chemical method.
Similarly, a PI film was prepared by the thermite imine method. A PAA solution (18wt% or less) was coated on a clean glass, and the glass was placed in an oven at 90 ℃ for 30 minutes to volatilize the solvent, thereby obtaining a solid PAA film. And (3) peeling off the solid PAA film from the quartz glass, fixing the film by a self-made frame, carrying out heat treatment for 10min according to isothermal procedures of 250 ℃ and 350 ℃, and cooling to room temperature to obtain the PI film prepared by a thermal method.
All PI films are subjected to carbonization graphitization heat treatment. In the carbonization process, the high-temperature furnace is heated to 1450 ℃ from room temperature at the heating rate of 2 ℃/min and then is naturally cooled. Then, graphitization heat treatment is carried out, and the graphite is heated from room temperature to 2950 ℃ at the heating rate of 5 ℃/min under the Ar atmosphere. And naturally cooling to room temperature to obtain the graphite film.
In the drawings:
FIG. 2 shows the infrared spectroscopy (FTIR) of all PI films, and FIG. 2 shows the FITR profile of all PI films. According to the report of the prior literature, the bending vibration peak of the C-O bond and the stretching vibration peak of the C-N bond are respectively 1720cm -1 And 1380cm -1[54] . In fig. 2, these two characteristic peaks appear for all PI films. Incomplete imidization at 1550cm -1 A vibrational characteristic peak of-CNH may appear. In FIG. 2, 1550cm in a chemically prepared PI film -1 The intensity of the peak at (a) is very weak, demonstrating that the film has been partially imidized. This peak even completely disappeared in the thermally prepared PI films, demonstrating that complete imidization has been achieved.
The in-plane thermal conductivity of the graphite in fig. 4 is calculated from the following formula:
λ (T) ＝α (T) ·ρ (T) ·c (T)
where α is the thermal diffusivity measured by a Flash thermal diffusivity instrument (LFA 447, NETZSCH), ρ is the density of each film, and c is measured by DSC (Q10, TA). All values were measured at 25 ℃ at room temperature. As shown in fig. 4, the thermal conductivity of the thermally imidized graphite PI film was only 22W/(m.k) at room temperature. However, all thermal conductivities increased significantly after the addition of the catalyst. The graphite PI film having a pyridine content of 3.5wt% had a thermal conductivity of 1092W/(m · K), which was 49 times higher than that of the thermal imidization.
The table above shows the grain size, graphitization degree, defect rate, and average in-plane crystallite size of the graphite film.
The graphitization degree of the graphite film prepared based on the PI-based film prepared by the thermal method is only 55%. In contrast, graphite films prepared based on chemically prepared PI-based films all had a degree of graphitization exceeding 85%. When the pyridine concentration is close to 3.5wt%, the prepared graphite film grows completely and is superior to the quality of the graphite film under other pyridine dosages. These results demonstrate that pyridine plays an important role in the graphitization of PI thin films. I of a film of heat-imidized PI D /I G About 50 times lower, and I of the chemical process D /I G Are all reduced by more than 80 times. These data indicate that pyridine addition accelerates the process from sp 3 To sp 2 The molecular structure of the hybridization changes. At the same time, this also reduces edge defects, facilitating the generation of oriented layered structures. The crystal size of the graphite film of the chemical method system is larger than that of the method. The La value of the graphite PI film containing 3.5% of pyridine is two times higher than that of the graphite PI film subjected to thermal imidization.
Claims (7)
1. A preparation method of a polyimide-based graphite film with high thermal conductivity is characterized by comprising the following steps:
s1, pre-imidizing by adopting a chemical imine method, adding diamine and dianhydride into a solvent in a reaction kettle, and reacting to generate polyamic acid;
s2, then adding a catalyst mixed solution, and quickly performing tape casting film formation after reaction to prevent the solvent in the reaction kettle from gelling, wherein the temperature in the tape casting process is lower than that required by the preparation of a common hot imine method;
and S3, finally, preparing the graphite film with high heat conductivity after carbonization and graphitization.
2. The preparation method of the polyimide-based graphite film with high thermal conductivity as claimed in claim 1, wherein the catalyst used in the chemical imine method is a mixed solution of pyridine and a dehydrating agent, wherein the catalyst is 2.5-4.0wt% of the mass fraction of polyamic acid, and the molar ratio of the dehydrating agent to polyamic acid is 1-3:1.
3. the method for preparing polyimide-based graphite film with high thermal conductivity according to claim 2, wherein the dehydrating agent is propionic anhydride or acetic anhydride.
4. The method for preparing a polyimide-based graphite film with high thermal conductivity according to claim 1, wherein the heating temperature during casting is 200-250 ℃.
5. The method for preparing the polyimide-based graphite film with high thermal conductivity according to claim 1, wherein the total mass of the dianhydride and the diamine accounts for 15 to 20 percent of the mass of the solvent.
6. The method for preparing a polyimide-based graphite film with high thermal conductivity as claimed in claim 1, wherein the diamine comprises one or more of 4' 4-diaminodiphenyl ether, diaminobenzophenone or its derivatives, diaminodiphenyl sulfone or its derivatives, and p-phenylenediamine.
7. The method for preparing a polyimide-based graphite film with high thermal conductivity according to claim 1, wherein the dianhydride comprises one or more of pyromellitic dianhydride, biphenyl tetracarboxylic dianhydride, diphenylmethane dianhydride-based compounds, ketone-containing carbonyl dianhydride compounds, and diphenyl ether dianhydride, and the solvent is dimethylacetamide and dimethylformamide.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2016017169A (en) * | 2014-07-11 | 2016-02-01 | 東レ・デュポン株式会社 | Graphite sheet polyimide film and production method thereof |
| US20200024142A1 (en) * | 2016-03-04 | 2020-01-23 | Shenzhen Danbond Technology Co., Ltd | Graphene film prepared with flexible polyimide and preparation method thereof |
| CN112456484A (en) * | 2019-12-27 | 2021-03-09 | 中天电子材料有限公司 | Graphite heat-conducting film and preparation method thereof |
| CN113353926A (en) * | 2021-05-25 | 2021-09-07 | 安徽国风塑业股份有限公司 | Polyimide film for preparing graphite film, high-thermal-conductivity graphite film prepared from polyimide film and preparation method of high-thermal-conductivity graphite film |
| CN114621475A (en) * | 2022-04-21 | 2022-06-14 | 广东工业大学 | Preparation method of metal organic salt/polyimide composite film |
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- 2022-07-07 CN CN202210795195.8A patent/CN115353392A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2016017169A (en) * | 2014-07-11 | 2016-02-01 | 東レ・デュポン株式会社 | Graphite sheet polyimide film and production method thereof |
| US20200024142A1 (en) * | 2016-03-04 | 2020-01-23 | Shenzhen Danbond Technology Co., Ltd | Graphene film prepared with flexible polyimide and preparation method thereof |
| CN112456484A (en) * | 2019-12-27 | 2021-03-09 | 中天电子材料有限公司 | Graphite heat-conducting film and preparation method thereof |
| CN113353926A (en) * | 2021-05-25 | 2021-09-07 | 安徽国风塑业股份有限公司 | Polyimide film for preparing graphite film, high-thermal-conductivity graphite film prepared from polyimide film and preparation method of high-thermal-conductivity graphite film |
| CN114621475A (en) * | 2022-04-21 | 2022-06-14 | 广东工业大学 | Preparation method of metal organic salt/polyimide composite film |
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