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CN-121554296-B - POD-based graphite film with interface affinity and preparation method thereof

CN121554296BCN 121554296 BCN121554296 BCN 121554296BCN-121554296-B

Abstract

The invention relates to the technical field of thermal management materials, in particular to a POD (polymer-oriented) base graphite film with interface affinity and a preparation method thereof, wherein the preparation method comprises the steps of preparing a modified POD polymer solution by polycondensation and copolymerization of terephthalic acid, isophthalic acid, hydrazine salt and a functional monomer in a fuming sulfuric acid system, wherein the functional monomer contains at least one group of carboxyl and hydroxyl; the modified POD polymer solution is subjected to film scraping, film forming through a coagulating bath, drying, oxygen plasma treatment to obtain a POD precursor film, and carbonization treatment and graphitization treatment to obtain the POD-based graphite film, wherein boric acid or ferric nitrate aqueous solution is sprayed on the surface of the carbonized film before graphitization treatment. The invention solves the problem of poor interfacial binding force of the traditional graphite film by a synergistic modification strategy of molecular design, surface activation and interface optimization, and is suitable for heat dissipation application in various fields.

Inventors

  • SHANG QING
  • ZHAO FEI
  • LI LILI
  • YAO KUNCHENG

Assignees

  • 烟台泰和新材高分子新材料研究院有限公司
  • 泰和新材集团股份有限公司

Dates

Publication Date
20260508
Application Date
20260122

Claims (8)

  1. 1. The preparation method of the POD-based graphite film with interface affinity is characterized by comprising the following steps of: s1, preparing a modified POD polymer solution by polycondensation and copolymerization of terephthalic acid, isophthalic acid, hydrazine salt and a functional monomer in a fuming sulfuric acid system, wherein the functional monomer contains at least one group of carboxyl and hydroxyl; s2, after the modified POD polymer solution is scraped into a film, the film is formed through a coagulating bath, dried, and then oxygen plasma treatment is carried out to obtain a POD precursor film; S3, carrying out carbonization treatment and graphitization treatment on the POD precursor film to obtain the POD-based graphite film, wherein boric acid or ferric nitrate aqueous solution is sprayed on the surface of the carbonized film before graphitization treatment; in the step S1, the molar ratio of terephthalic acid to isophthalic acid to hydrazine salt to functional monomer is (5-8): 0.5-1.2): 1-2): 0.1-0.5; in the step S2, after film scraping, film forming is carried out through three-stage coagulating baths, wherein the temperature of each stage coagulating bath is 20-40 ℃; the first stage coagulating bath comprises 40-60% of sulfuric acid water solution by mass concentration for 5-10min; the second-stage coagulating bath comprises a sulfuric acid aqueous solution with the mass concentration of 20-30% and the time of 10-20min; and the third stage of coagulating bath, namely 5-15% of sulfuric acid aqueous solution by mass concentration for 10-20min.
  2. 2. The method for producing a POD-based graphite film having interface affinity according to claim 1, wherein the functional monomer is at least one selected from the group consisting of 5-hydroxyisophthalic acid, 3, 5-dicarboxybenzoic acid, and 4-hydroxybenzoic acid; the hydrazine salt is at least one selected from hydrazine sulfate or hydrazine hydrochloride.
  3. 3. The preparation method of the POD-based graphite film with interface affinity according to claim 1, wherein the specific operation in the step S1 is that terephthalic acid, isophthalic acid, hydrazine salt and functional monomer are added into fuming sulfuric acid to be uniformly dispersed, then the temperature is raised to 70-90 ℃ and stirred for 1-2 h, then the temperature is continuously raised to 120-140 ℃ and stirred for 2-4h, benzoic acid is added as a blocking agent, then the temperature is raised to 140-170 ℃ and stirred for 0.5-2h, and then the modified POD polymer solution is obtained through defoaming treatment.
  4. 4. The method for producing a POD-based graphite film having interfacial affinity according to claim 3, wherein the ratio of the molar amount of benzoic acid to the total molar amount of terephthalic acid, isophthalic acid, hydrazine salt, functional monomer is (0.01-0.03): 1; The mass ratio of the total mass of the terephthalic acid, the isophthalic acid, the hydrazine salt and the functional monomer to the fuming sulfuric acid is (0.05-0.15): 0.85-0.95.
  5. 5. The method for preparing a POD-based graphite film having interface affinity according to claim 1, wherein the oxygen plasma treatment is performed under the conditions of 50-100W for 30-60S in step S2.
  6. 6. The method for preparing a POD-based graphite film having interface affinity according to claim 1, wherein in step S3, the carbonization process is as follows: Heating to 200-300 ℃ at a heating rate of 3-10 ℃ per minute for pre-oxidation for 1-3h; Heating to 500-600 ℃ at a heating rate of 2-5 ℃ per minute for decomposing for 1-3h; Heating to 1200-1500 ℃ at the heating rate of 2-5 ℃ per minute for carbonization for 1-3h.
  7. 7. The method for producing a POD-based graphite film having interface affinity according to claim 1, wherein in step S3, boric acid or an aqueous solution of nitric acid having a mass concentration of 1% -5% is sprayed on the surface of the carbonized film; The graphitization treatment process comprises the following steps: Heating to 2000-2200 ℃ at a heating rate of 3-10 ℃ per minute, and preserving heat for 1-3h; heating to 2400-2500 ℃ at a heating rate of 2-5 ℃ per min, and preserving heat for 1-3h; heating to 2600-3000 deg.C at a heating rate of 2-5 deg.C/min, and maintaining for 1-3h.
  8. 8. A POD-based graphite film having interface affinity, characterized in that the POD-based graphite film is produced according to the production method of any one of claims 1 to 7.

Description

POD-based graphite film with interface affinity and preparation method thereof Technical Field The invention relates to a POD-based graphite film with interface affinity and a preparation method thereof, belonging to the technical field of thermal management materials. Background With the rapid development of technologies such as 5G communication and high-power electronic devices, the demand for efficient heat dissipation materials is increasing. Graphite films are ideal thermal management materials because of their excellent in-plane thermal conductivity properties (typically > 1000W/(m-K)). In recent years, graphite films prepared by taking aromatic Polyoxadiazole (POD) as a precursor have the remarkable advantages that compared with the traditional Polyimide (PI) base graphite film, the POD base graphite film has higher carbonization yield and more ordered graphitization structure, the heat conductivity coefficient of the POD base graphite film can reach more than 1500W/(m.K), the thickness controllability is better (50-200 mu m), and the graphite film has wide application prospect in the fields of ultrathin vapor chamber, high-power chip heat dissipation and the like. However, in practical applications, the POD-based graphite film is usually used in combination with copper foil, aluminum material, epoxy resin, or other materials, and the inherent interface bonding defect severely restricts performance. The interface problem of the POD-based graphite film mainly stems from the intrinsic characteristics that, firstly, the POD molecular chain contains a rigid aromatic ring and an oxadiazole heterocyclic structure, although the POD molecular chain gives excellent thermal stability to the material, the POD molecular chain also causes surface chemical inertness, the chemical bonding capability with a metal/ceramic substrate is weak, the measured peeling strength is generally lower than 0.5N/cm, and secondly, the POD molecular chain is converted into a highly oriented sp2 carbon layer in the graphitization process, and the crystal structure is favorable for in-plane heat conduction but has poor matching degree with phonon vibration spectrum of heterogeneous materials (such as copper and epoxy resin). These problems make it difficult to achieve efficient thermal energy transfer of the graphite film in practical heat dissipating systems, even with device failure due to interfacial delamination. In the prior art, the interface modification of the graphite film is partially explored, but all the graphite films have obvious limitations. For example, it is proposed in patent application publication No. CN118086990A to introduce hexagonal defects on the surface of a graphite film by high-temperature air etching (500-700 ℃) to increase the specific surface area, and then to enhance the bonding force by electroplating copper. Although the method can improve the peeling strength to 1.5N/cm, the high-temperature etching can damage the lattice integrity of graphite, so that the tensile strength is reduced by more than 30 percent, and strict acid-base cleaning (such as KOH alkaline cleaning to remove oxide and HCl acid cleaning to activate the surface) is needed before electroplating, so that the process is complex and ion pollution is easy to introduce. Another patent application with CN117777958A uses parylene vapor deposition to form an ultrathin insulating layer (< 15 μm) on the surface of a graphite film, and the method can improve interface wettability, but has the difficulty of controlling thickness, namely, when the deposited layer is <0.5 μm, the scratch resistance is insufficient, and when the deposited layer is >10 μm, the overall heat conductivity is reduced by more than 20%. In addition, these methods are only post-treatment for the finished graphite film, and cannot be synergistically optimized from the global point of view of molecular design-preparation process-structural evolution. The key of the bottleneck of the prior art is that the existing modification scheme is mostly a 'local repair' strategy, or only focuses on surface morphology regulation (such as etching and coating), or only focuses on single performance optimization (such as conductivity and insulativity), and lacks systematic coordination on POD precursor molecular structure design, interface construction in a film forming process and graphitization behavior regulation. This improved mode of fragmentation results in limited performance improvement and often accompanies significant side effects (e.g., mechanical damage, thermal conductivity decay). Therefore, development of a synergistic modification strategy for the whole process of POD precursor preparation-film formation-graphitization is needed, active functional groups are introduced at a molecular level to enhance chemical bonding capability, a multi-level coarse structure is constructed at a mesoscopic level to promote mechanical interlocking effect, thermal stress distribution is optim