Dopamine non-covalent bond modified heat dissipation film and preparation method thereof
By using a dopamine non-covalent modification method to enhance the interfacial interaction between boron nitride and polyurethane, the conductivity risk of heat dissipation film materials in high-power-density electronic devices and the problems of complex and environmentally polluting traditional modification processes are solved, thus realizing the preparation of efficient and environmentally friendly heat dissipation films.
Patent Information
- Application Number
- CN202511798873.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-02
- Publication Date
- 2026-01-09
AI Technical Summary
Existing heat dissipation film materials pose a conductivity risk in high power density electronic devices, and traditional modification processes are complex, pollute the environment, and are not suitable for large-scale production.
By introducing dopamine non-covalent bond modification, dopamine groups are introduced into polyurethane, enhancing the interfacial interaction between boron nitride and polyurethane, forming a stable interfacial bonding system of "boron nitride-dopamine-polyurethane", simplifying the preparation process and adapting to large-scale production.
It improves the thermal conductivity and insulation properties of the heat dissipation film, meets the performance requirements of electronic devices, has an environmentally friendly process that is suitable for mass production, and reduces interfacial thermal resistance.
Smart Images
Figure CN121293464A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of heat dissipation technology of polymer materials, specifically to a dopamine non-covalently modified heat dissipation film and its preparation method, which is suitable for insulation and heat dissipation scenarios of high power density electronic devices (such as 5G base stations, new energy vehicle chips, consumer electronic terminals, etc.). Background Technology
[0002] With the rapid development of miniaturization and high performance in electronic devices, the power density per unit volume has increased significantly, and heat dissipation efficiency has become a core factor restricting the performance and lifespan of equipment. Traditional heat dissipation materials (such as thermal grease) have certain thermal conductivity, but they have drawbacks such as poor flexibility and easy aging and failure after long-term use; while heat dissipation films, due to their high in-plane thermal conductivity and excellent flexible adhesion, have become the preferred heat dissipation solution for high-power devices.
[0003] In related technologies, most mainstream heat dissipation films on the market are currently made of carbon-based materials (such as graphite films and graphene heat dissipation films). Although these materials have excellent thermal conductivity, they are also electrically conductive, which can easily cause short circuits in insulation and heat dissipation scenarios of precision electronic devices (such as between chips and circuit boards), thus limiting their application scope. To solve this problem, the industry has turned its attention to boron nitride (BN), which has both high thermal conductivity and electrical insulation: the layered crystal structure of boron nitride gives it an in-plane thermal conductivity of 300-400 W / (m·K) and a volume resistivity greater than 10 Ω·m. 14 Ω·cm is an ideal insulating and thermally conductive filler. However, boron nitride lacks active functional groups on its surface, resulting in extremely poor compatibility with the polyurethane (PU) matrix commonly used in heat dissipation films: agglomeration easily occurs during mixing, leading to interfacial voids and thermal resistance zones within the heat dissipation film, significantly weakening its thermal conductivity; simultaneously, agglomeration also disrupts the continuity of the polyurethane matrix, reducing the mechanical strength of the heat dissipation film. To improve compatibility, existing technologies often employ strong acids (such as concentrated sulfuric acid or concentrated nitric acid) or strong bases to modify the surface of boron nitride, introducing functional groups such as hydroxyl and carboxyl groups through etching. However, such processes have significant drawbacks: firstly, strong acids and bases easily destroy the original crystal lattice structure of boron nitride, leading to a decrease in its thermal conductivity; secondly, the reaction process generates a large amount of corrosive waste liquid, resulting in high treatment costs and environmental pollution, failing to meet green manufacturing requirements; and thirdly, the modification process is complex, requiring high-temperature reflux and multiple washings, making it difficult to adapt to large-scale production. Summary of the Invention
[0004] To overcome the shortcomings of existing technologies, the present invention aims to provide a dopamine non-covalently modified heat dissipation film and its preparation method. The present invention introduces biomimetic dopamine groups into polyurethane through chemical modification. The hydroxyl and amino groups of dopamine on the polyurethane chain and the benzene ring structure of dopamine enhance the non-covalent bond interaction between boron nitride and polyurethane (strong hydrogen bonding and π-π stacking effect generated by the conjugated plane of benzene ring and boron nitride), thereby strengthening the interfacial interaction between polyurethane and boron nitride, effectively improving the thermal conductivity of the boron nitride heat dissipation film. The process is simple, the conditions are mild, and it can be adapted to large-scale production scenarios.
[0005] The first aspect of the present invention is to provide a dopamine non-covalently modified heat dissipation film, which is prepared from the following raw materials in parts by weight: 10-15 parts diisocyanate, 20-150 parts polypolyol, 0.03-0.3 parts dibutyltin dilaurate (DBTDL), 10-30 parts dopamine hydrochloride (DACL), 6-20 parts anhydrous triethylamine (Et3N), 80-200 parts anhydrous N,N-dimethylformamide (DMF), and 270-2000 parts boron nitride.
[0006] In a first aspect of the invention, as a preferred embodiment, the boron nitride is in the form of a sheet with a thickness of 5-50 μm.
[0007] In a first aspect of the invention, as a preferred embodiment, the diisocyanate is selected from one or more of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate; Alternatively, the polypolyol is selected from one or more of polycaprolactone diol, polytetrahydrofuran diol, and polyhexanediol carbonate diol with a relative molecular weight of 400-4000.
[0008] In a first aspect of the present invention, as a preferred embodiment, the thermal conductivity of the heat dissipation film is not less than 19.1 W / (m·K), the breakdown voltage is not less than 95.6 kV / mm, and the tensile strength is not less than 0.88 MPa.
[0009] In a first aspect of the present invention, as a preferred embodiment, the raw materials contain 13-26 parts by weight of dopamine hydrochloride, 7-14 parts by weight of anhydrous triethylamine, and 390-495 parts by weight of boron nitride.
[0010] A second aspect of this invention provides a method for preparing a dopamine non-covalently modified heat dissipation film, comprising the following steps: a) Add the prescribed amounts of diisocyanate, polypolyol, and dibutyltin dilaurate to 40-100 parts of anhydrous N,N-dimethylformamide under a nitrogen atmosphere, reflux and condense to react, and generate a polyurethane prepolymer with isocyanate groups at the end, and cool to room temperature for later use. b) Add the prescribed amount of dopamine hydrochloride and the prescribed amount of anhydrous triethylamine to 40-100 parts of anhydrous N,N-dimethylformamide, mix them evenly in a low-temperature nitrogen atmosphere, carry out the activation reaction, and filter to obtain a dopamine (DA) solution. c) The polyurethane prepolymer from step a) is mixed with the dopamine solution from step b) and reacted to prepare a dopamine-modified polyurethane solution, which is then cooled. d) Add the prescribed amount of boron nitride to the cooled dopamine-modified polyurethane solution from step c), mix to prepare a slurry, coat it, and then hot-press it to obtain the heat dissipation film.
[0011] In a second aspect of the present invention, as a preferred embodiment, in step a), the reaction temperature of the condensation reflux reaction is 30.0-70.0°C, and the reaction time is 1.0-5.0 h.
[0012] In a second aspect of the present invention, as a preferred embodiment, in step b), the activation reaction temperature of the low-temperature nitrogen atmosphere is below room temperature, and the activation reaction time is 0.5-3.0 h.
[0013] In a second aspect of the present invention, as a preferred embodiment, in step c), the reaction is carried out under a nitrogen atmosphere, the reaction temperature is 30.0-70.0°C, and the reaction time is 1.0-5.0 h.
[0014] In a second aspect of the invention, as a preferred embodiment, in step d), the hot pressing includes preheating for 5.0-10.0 min, then hot pressing at 120.0-150.0°C for 10.0-30.0 min, and finally cooling for 3.0-10.0 min.
[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: Based on the dopamine biomimetic adhesion mechanism and interfacial chemistry principle, this invention improves the thermal conductivity of the heat dissipation film by optimizing the interfacial interaction between the polyurethane matrix and boron nitride in the heat dissipation film, simplifies the preparation process, and enables the heat dissipation film to be adapted to a wider range of application scenarios.
[0016] In traditional heat dissipation film systems, the thermally conductive filler boron nitride, lacking active functional groups on its surface, easily forms voids and thermal resistance zones at the interface with the polyurethane molecular chain, resulting in low heat transfer efficiency. Furthermore, the modification processes for boron nitride often involve strong acids and alkalis, which can easily damage the boron nitride lattice, fail to meet environmental protection requirements, and are costly. This invention introduces dopamine groups into the polyurethane structure through a simple chemical modification method. The dopamine's adhesive groups and its benzene rings interact with the conjugate plane of the boron nitride filler through π-π stacking, enhancing the interaction force between polyurethane and boron nitride. This constructs a "boron nitride-dopamine-polyurethane" interfacial bonding system, effectively reducing interfacial thermal resistance and theoretically providing an efficient heat transfer pathway, thereby improving the thermal conductivity of the heat dissipation film.
[0017] The process of this invention is mild and environmentally friendly, suitable for large-scale production. It requires no strong acids or alkalis throughout the entire process, achieving interface optimization solely through dopamine modification of the polyurethane matrix. No corrosive waste liquid is generated, meeting green manufacturing standards. Furthermore, the reaction steps are simple (completed in 4 steps), key parameters are easily controlled, and it can be directly integrated into existing polymer membrane production lines, resulting in high production efficiency. The thermal conductivity of the heat dissipation film of this invention is ≥19.1 W / (m·K) (up to 23.8 W / (m·K)), breakdown voltage ≥95.6 kV / mm (up to 114.5 kV / mm), and tensile strength ≥0.88 MPa (up to 1.54 MPa), fully meeting the performance requirements of electronic devices for heat dissipation films. Attached Figure Description
[0018] Figure 1 : Schematic diagram of the preparation principle of the dopamine non-covalently modified heat dissipation film of the present invention; Figure 2 Scanning electron microscope (SEM) image of the dopamine non-covalently modified heat dissipation film prepared in Example 1 (test voltage 10.00 kV, magnification × 1000); the image shows that boron nitride is uniformly dispersed, without obvious agglomeration, and is tightly bonded to the dopamine modified polyurethane matrix; Figure 3 SEM image of the heat dissipation film (commercially available TPU + boron nitride) prepared in Comparative Example 2 (test conditions same). Figure 2 As shown in the figure, boron nitride agglomerates are obvious, with gaps between it and the TPU matrix, and the interface bonding is loose. Detailed Implementation
[0019] The invention will now be further described with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Unless otherwise specified, the materials and equipment used in this embodiment are commercially available. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.
[0020] The first aspect of the present invention is to provide a dopamine non-covalently modified heat dissipation film, which is prepared from the following raw materials in parts by weight: 10-15 parts diisocyanate, 20-150 parts polypolyol, 0.03-0.3 parts dibutyltin dilaurate (DBTDL), 10-30 parts dopamine hydrochloride (DACL), 6-20 parts anhydrous triethylamine (Et3N), 80-200 parts anhydrous N,N-dimethylformamide (DMF), and 270-2000 parts boron nitride.
[0021] The above raw materials and their weight percentages are preferred raw material compositions and weight percentage ranges for this application. The heat dissipation film made from the above raw materials has good thermal conductivity and insulation.
[0022] In a first aspect of the invention, as a preferred embodiment, the boron nitride is in the form of a sheet with a thickness of 5-50 μm. This ensures the construction of a high thermal conductivity channel (the sheet structure facilitates heat transfer), avoids agglomeration through size control, and retains the insulating properties of boron nitride itself.
[0023] In a first aspect of the invention, as a preferred embodiment, the diisocyanate is selected from one or more of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate.
[0024] In a first aspect of the present invention, as a preferred embodiment, the polyol is selected from one or more of polycaprolactone diol, polytetrahydrofuran diol, and polyhexanediol carbonate diol, which have a relative molecular weight of 400-4000.
[0025] In a first aspect of the present invention, as a preferred embodiment, the thermal conductivity of the heat dissipation film is not less than 19.1 W / (m·K), the breakdown voltage is not less than 95.6 kV / mm, and the tensile strength is not less than 0.88 MPa.
[0026] In a first aspect of the present invention, as a preferred embodiment, the raw materials contain 13-26 parts by weight of dopamine hydrochloride, 7-14 parts by weight of anhydrous triethylamine, and 390-495 parts by weight of boron nitride.
[0027] Please refer to Figure 1 The second aspect of this invention is to provide a method for preparing a dopamine non-covalently modified heat dissipation film, comprising the following steps: a) Add the prescribed amounts of diisocyanate, polypolyol, and dibutyltin dilaurate to 40-100 parts of anhydrous N,N-dimethylformamide under a nitrogen atmosphere, reflux and condense to react, and generate a polyurethane prepolymer with isocyanate groups at the end, and cool to room temperature for later use. b) Add the prescribed amount of dopamine hydrochloride and the prescribed amount of anhydrous triethylamine to 40-100 parts of anhydrous N,N-dimethylformamide, mix them evenly in a low-temperature nitrogen atmosphere, carry out the activation reaction, and filter to obtain a dopamine (DA) solution. c) The polyurethane prepolymer from step a) is mixed with the dopamine solution from step b) and reacted to prepare a dopamine-modified polyurethane solution, which is then cooled. d) Add the prescribed amount of boron nitride to the cooled dopamine-modified polyurethane solution from step c), mix to prepare a slurry, coat it, and then hot-press it to obtain the heat dissipation film.
[0028] Based on the above scheme, this invention grafts dopamine groups onto the polyurethane chain through chemical modification: the hydroxyl and amino groups in the dopamine molecule can form strong hydrogen bonds with the surface of boron nitride, and at the same time, the benzene ring structure of dopamine and the conjugate plane of boron nitride produce π-π stacking effect. The two work together to construct a stable interface bonding system of "boron nitride-dopamine-polyurethane", which solves the compatibility problem between boron nitride and polyurethane at the molecular level and reduces the interfacial thermal resistance; and there is no need to modify boron nitride with strong acids or bases, so as to completely retain its lattice integrity and insulating properties.
[0029] In a second aspect of the invention, as a preferred embodiment, in step a), the reflux reaction temperature is 30.0-70.0°C, and the reaction time is 1.0-5.0 h. In this step, the isocyanate groups in the diisocyanate form stable urethane bonds with the hydroxyl groups in the polyol, thereby extending the polymer chain.
[0030] In a second aspect of the invention, as a preferred embodiment, in step b), the activation reaction temperature under the low-temperature nitrogen atmosphere is below room temperature, and the activation reaction time is 0.5-3.0 h. This step yields an active dopamine solution to enable rapid subsequent bonding of dopamine groups to the polyurethane prepolymer.
[0031] In a second aspect of the invention, as a preferred embodiment, in step c), the reaction is carried out under a nitrogen atmosphere at a temperature of 30.0-70.0°C for a time of 1.0-5.0 h. In this step, the amino and isocyanate groups in dopamine react to generate urea groups, which rapidly and efficiently strengthen the intramolecular and intermolecular hydrogen bonding of polyurethane, forming physical crosslinks and enhancing the cohesive energy of the polyurethane.
[0032] In a second aspect of the invention, as a preferred embodiment, step d) involves hot pressing, which includes preheating for 5.0-10.0 min, hot pressing at 120.0-150.0°C for 10.0-30.0 min, and finally cooling for 3.0-10.0 min. In this step, if the preheating time is too short, boron nitride cannot fully bond with the polyurethane; if the time is too long, the polyurethane is prone to oxidation and discoloration, affecting its mechanical properties. If the cooling time is too short, cracks are likely to occur in the internal structure of the heat dissipation film; if the cooling time is too long, time costs are increased. In this step, dopamine and polyurethane further crosslink. The adhesive groups of dopamine can enhance the hydrogen bonding between polyurethane molecules and boron nitride. Simultaneously, the benzene ring of dopamine and the conjugate plane of boron nitride generate a π-π stacking effect, increasing the interaction force between polyurethane and boron nitride, improving their compatibility, and thus enhancing the thermal conductivity of the heat dissipation film.
[0033] The following are some embodiments listed in this application, which further illustrate this application.
[0034] Example 1
[0035] A dopamine non-covalently modified heat dissipation film is prepared by the following steps: Step a (Prepolymer Preparation): Add 5 parts MDI, 5 parts IPDI (total 10 parts diisocyanate) and 20 parts PCL1000 (polyol) to 40 parts anhydrous N,N-dimethylformamide, control the molar ratio of diisocyanate to polyol R=2.0, add 0.05 parts DBTDL, and reflux at 60.0℃ for 2.0h under nitrogen atmosphere to obtain isocyanate-terminated polyurethane prepolymer, and cool to room temperature; Step b (Dopamine activation): Add 13 parts of dopamine hydrochloride (DACL) and 7 parts of anhydrous Et3N to 20 parts of anhydrous N,N-dimethylformamide, stir and activate for 1.0 h under a nitrogen atmosphere at low temperature (10℃), and filter to obtain an active dopamine solution. Step c (Preparation of modified polyurethane): The prepolymer from step a is mixed with the active dopamine solution from step b, and reacted at 60.0℃ for 3.0h under a nitrogen atmosphere to obtain a dopamine-modified polyurethane solution, which is then cooled to room temperature. Step d (hot pressing): Add 390 parts of boron nitride (size 10-20μm) to the above modified polyurethane solution and stir evenly to prepare a slurry; after coating, hot press: preheat for 6.0 min, hot press at 150.0℃ for 15.0 min, cool for 5.0 min to obtain the target heat dissipation film.
[0036] Performance test results: thermal conductivity 19.1 W / (m·K), breakdown voltage 95.6 kV / mm, tensile strength 1.15 MPa.
[0037] Table 1, Parameter Screening Experimental Data Recording (Taking the Dopamine Hydrochloride Dosage as an Example).
[0038] Table 1
[0039] As shown in Table 1, when the amount of dopamine hydrochloride is less than 10 parts, the tensile strength of the heat dissipation film is low and it is easy to break during processing; when the amount of dopamine hydrochloride is greater than 26 parts, the tensile strength of the heat dissipation film is too high, the processing is difficult and the cost is high. Therefore, the amount of dopamine hydrochloride is 10-30 parts (preferably 13-26 parts), which is the optimal range that balances effect and cost.
[0040] Example 2
[0041] The difference between this embodiment and Example 1 is that the diisocyanate in step a is replaced with 5 parts TDI (toluene diisocyanate) and 5 parts IPDI (isophorone diisocyanate) (10 parts in total), while the remaining raw material amounts and process parameters are the same as in Example 1.
[0042] Performance test results: thermal conductivity 20.4 W / (m·K), breakdown voltage 98.5 kV / mm, tensile strength 0.95 MPa; the results show that the introduction of TDI can improve the reaction rate, make the polyurethane chain structure more uniform, and slightly improve the thermal conductivity.
[0043] Example 3
[0044] The difference between this embodiment and Example 1 is that the polyol in step a is replaced with 20 parts of polyhexanediol carbonate diol (PCDL1000), while the remaining raw material amounts and process parameters are the same as in Example 1.
[0045] Performance test results: thermal conductivity 19.5 W / (m·K), breakdown voltage 103.4 kV / mm, tensile strength 1.30 MPa; the results show that PCDL has stronger carbonate polarity, which can enhance hydrogen bonding with dopamine, resulting in better mechanical and insulation properties.
[0046] Example 4
[0047] The difference between this embodiment and Embodiment 1 is that the amount of DACL in step b is adjusted to 26 parts and the amount of Et3N is adjusted to 14 parts (the amounts of other raw materials remain unchanged), while the remaining process parameters are the same as in Embodiment 1.
[0048] Performance test results: thermal conductivity 20.3 W / (m·K), breakdown voltage 110.3 kV / mm, tensile strength 1.54 MPa; the results show that increasing the amount of dopamine can enhance the non-covalent bond interaction with boron nitride, making the interfacial bonding more stable and improving all properties.
[0049] Example 5
[0050] The difference between this embodiment and Embodiment 1 is that the amount of boron nitride in step d is adjusted to 495 parts (the amount of other raw materials remains unchanged), while the other process parameters are the same as in Embodiment 1.
[0051] Performance test results: thermal conductivity 23.8 W / (m·K), breakdown voltage 114.5 kV / mm, tensile strength 0.88 MPa; the results show that increasing the amount of boron nitride can build a denser thermal conductivity channel, significantly improving thermal conductivity and insulation performance, but the proportion of polyurethane matrix decreases and the mechanical properties decrease slightly (but still meet the application requirements).
[0052] Comparative Example 1 (without dopamine modification)
[0053] The difference between this comparative example and Example 1 is that steps b and c are omitted, and 390 parts of boron nitride are directly added to the polyurethane prepolymer solution obtained in step a. The remaining process parameters are the same as in Example 1. The formula is: 5 parts MDI, 5 parts IPDI, 20 parts PCL1000, 0.05 parts DBTDL, 30 parts DMF, and 255 parts boron nitride.
[0054] Performance test results: thermal conductivity 16.7 W / (m·K), breakdown voltage 75.7 kV / mm, tensile strength 0.76 MPa; the results show that without dopamine modification, boron nitride has poor compatibility with polyurethane, high interfacial thermal resistance, and its performance is significantly inferior to that of the present invention.
[0055] Comparative Example 2 (Commercially Available TPU Matrix)
[0056] The difference between this comparative example and Example 1 is that 40 parts of commercially available thermoplastic polyurethane (TPU) dissolved in 30 parts of DMF were used to replace the dopamine-modified polyurethane in step ac, and 270 parts of boron nitride were added. The remaining process parameters were the same as in Example 1.
[0057] Performance test results: thermal conductivity 15.5 W / (m·K), breakdown voltage 88.1 kV / mm, tensile strength 1.22 MPa; SEM image ( Figure 3 The results showed significant boron nitride agglomeration, indicating that commercially available TPU lacks dopamine groups and cannot form a stable interface with boron nitride, resulting in poor thermal conductivity.
[0058] Comparative Example 3 (Covalent Bond Modification of Boron Nitride)
[0059] The difference between this comparative example and Comparative Example 2 is that boron nitride is first covalently modified (hydroxylated) before preparing the heat dissipation film. The specific steps are as follows: Boron nitride powder is added to a mixture of concentrated H₂SO₄ and concentrated HNO₃ (volume ratio 3:1), and then stirred in an oil bath at 80.0-120.0℃ for 6 hours. After cooling, deionized water is added for dilution, and the mixture is filtered and repeatedly washed with deionized water until the filtrate is neutral. The washed sample is then dried in a vacuum drying oven at 60.0-80.0℃ for 6-12 hours to finally obtain hydroxylated boron nitride powder. The remaining process parameters are the same as in Comparative Example 2. The formulation is: 40 parts TPU, 30 parts DMF, and 270 parts covalently modified boron nitride.
[0060] Performance test results: thermal conductivity 18.5 W / (m·K), breakdown voltage 94.3 kV / mm, tensile strength 1.03 MPa; the results show that although covalent modification improves compatibility, strong acid destroys the boron nitride lattice, and the thermal conductivity is still lower than that of the present invention (Example 1: 19.1 W / (m·K)), and the process is complicated and pollutes the environment.
[0061] Performance test comparison: The thermal conductivity and breakdown voltage of each sample are summarized in Table 2. In Table 2, the thermal conductivity of the heat dissipation film was obtained by testing with a laser flash meter (LFA467, Netzsch) according to GB / T22588; the breakdown voltage was obtained by testing with Netzsch HT-BV according to ASTM D149; and the tensile strength was tested according to ASTM D412-2006.
[0062] Table 2
[0063] Comparative Examples 1-3: Changing the structure of isocyanate and polyol in the polyurethane matrix affects the thermal conductivity and breakdown voltage of the heat dissipation film; the core reason is that the structural difference between the two controls the crosslinking density of the polyurethane and the hydrogen bonding with boron nitride, thereby changing the performance.
[0064] Comparing Examples 1 and 4: Adjusting the amount of dopamine groups introduced into the polyurethane matrix will affect the performance of the heat dissipation film; because the increase of dopamine groups can enhance the non-covalent bond interaction between polyurethane and boron nitride, and improve their compatibility.
[0065] Comparing Examples 1 and 5: Increasing the amount of boron nitride can significantly improve the thermal conductivity and breakdown voltage of the heat dissipation film, but the tensile properties of the heat dissipation film decrease significantly when the polyurethane content is reduced.
[0066] Comparative Examples 1 and 1-2: Compared to polyurethane prepolymers and TPU matrices, heat dissipation films based on dopamine-modified polyurethane exhibit superior thermal conductivity and insulation properties. Heat dissipation films prepared by directly adding dopamine to polyurethane prepolymers suffer from low crosslinking and significantly reduced tensile strength due to the lack of dopamine.
[0067] Comparative Example 1 and Comparative Example 3: Compared with covalent modification of boron nitride, the heat dissipation film with dopamine-modified polyurethane as the matrix and enhanced non-covalent interaction with boron nitride has better thermal conductivity and insulation properties. This shows that the non-covalent modification method better ensures the integrity of the boron nitride lattice and enhances the compatibility between boron nitride and polyurethane.
[0068] Figure 2 and Figure 3 The images show scanning electron microscope (SEM) images of the heat dissipation films in Example 1 and Comparative Example 2, respectively, with a test voltage of 10.00 kV. Comparative analysis of the images shows that the agglomeration of boron nitride in Example 1 is significantly improved compared to Comparative Example 2. This is because the binding ability of boron nitride to the polymer matrix dopamine-modified polyurethane is enhanced, making it less prone to agglomeration between fillers.
[0069] The thermal conductivity of Examples 1-5 (19.1-23.8 W / (m·K)) was higher than that of Comparative Examples 1-3 (15.5-18.5 W / (m·K)), proving that the non-covalent bond effect of dopamine can effectively reduce interfacial thermal resistance. The breakdown voltages of Examples 1-5 (95.6-114.5 kV / mm) are significantly higher than those of Comparative Example 1 (75.7 kV / mm), indicating that the present invention fully retains the insulating properties of boron nitride. Comparative Example 3 requires strong acids and bases, while the embodiments of the present invention are mild throughout the process, with no pollutant emissions, and the steps are simple and can be mass-produced.
[0070] In summary, this invention effectively addresses the technical challenges of existing heat dissipation films by modifying the polyurethane matrix with dopamine non-covalent bonds, combining performance and process advantages, and possessing extremely high industrial application value.
[0071] The dopamine non-covalently modified heat dissipation film and its preparation method of the present invention have readily available raw materials, mild process, and easily controllable parameters, and can be mass-produced through existing polymer film production lines; the product has high thermal conductivity, excellent insulation and mechanical stability, and can be widely used in insulation and heat dissipation scenarios of electronic devices such as 5G base stations, new energy vehicle chips, smartphones, and laptops, and can meet the heat dissipation requirements in different scenarios, with significant industrial applicability and economic benefits.
[0072] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.
Claims
1. A dopamine non-covalently modified heat dissipation film, characterized in that, It is prepared from the following raw materials in parts by weight: 10-15 parts diisocyanate, 20-150 parts polyol, 0.03-0.3 parts dibutyltin dilaurate, 10-30 parts dopamine hydrochloride, 6-20 parts anhydrous triethylamine, 80-200 parts anhydrous N,N-dimethylformamide, and 270-2000 parts boron nitride.
2. The dopamine non-covalently modified heat dissipation film as described in claim 1, characterized in that, The boron nitride is in the form of flakes with a thickness of 5-50 μm.
3. The dopamine non-covalently modified heat dissipation film as described in claim 1, characterized in that, The diisocyanate is selected from one or more of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate; Alternatively, the polypolyol is selected from one or more of polycaprolactone diol, polytetrahydrofuran diol, and polyhexanediol carbonate diol with a relative molecular weight of 400-4000.
4. The dopamine non-covalently modified heat dissipation film as described in claim 1, characterized in that, The thermal conductivity of the heat dissipation film is not less than 19.1 W / (m·K), the breakdown voltage is not less than 95.6 kV / mm, and the tensile strength is not less than 0.88 MPa.
5. The dopamine non-covalently modified heat dissipation film as described in claim 1, characterized in that, In the raw materials, the dopamine hydrochloride is present in 13-26 parts by weight, the anhydrous triethylamine is present in 7-14 parts by weight, and the boron nitride is present in 390-495 parts by weight.
6. A method for preparing a dopamine non-covalently modified heat dissipation film as described in any one of claims 1-5, comprising the following steps: a) Add the prescribed amounts of diisocyanate, polypolyol, and dibutyltin dilaurate to 40-100 parts of anhydrous N,N-dimethylformamide under a nitrogen atmosphere, reflux and condense to react, and generate a polyurethane prepolymer with isocyanate groups at the end, and cool to room temperature for later use. b) Add the prescribed amount of dopamine hydrochloride and the prescribed amount of anhydrous triethylamine to 40-100 parts of anhydrous N,N-dimethylformamide, mix them evenly in a low-temperature nitrogen atmosphere, carry out the activation reaction, and filter to obtain a dopamine solution. c) The polyurethane prepolymer from step a) is mixed with the dopamine solution from step b) and reacted to prepare a dopamine-modified polyurethane solution, which is then cooled. d) Add the prescribed amount of boron nitride to the cooled dopamine-modified polyurethane solution from step c), mix to prepare a slurry, coat it, and then hot-press it to obtain the heat dissipation film.
7. The method for preparing the dopamine non-covalently modified heat dissipation film as described in claim 6, characterized in that, In step a), the reaction temperature of the condensation reflux reaction is 30.0-70.0℃, and the reaction time is 1.0-5.0h.
8. The method for preparing the dopamine non-covalently modified heat dissipation film as described in claim 6, characterized in that, In step b), the activation reaction temperature of the low-temperature nitrogen atmosphere is below room temperature, and the activation reaction time is 0.5-3.0 h.
9. The method for preparing the dopamine non-covalently modified heat dissipation film as described in claim 6, characterized in that, In step c), the reaction is carried out under a nitrogen atmosphere at a temperature of 30.0-70.0°C for a time of 1.0-5.0 h.
10. The method for preparing the dopamine non-covalently modified heat dissipation film as described in claim 6, characterized in that, In step d), the hot pressing includes preheating for 5.0-10.0 min, then hot pressing at 120.0-150.0℃ for 10.0-30.0 min, and finally cooling for 3.0-10.0 min.