Heat conduction assembly and use thereof

Abstract

A first aspect of the present invention provides a heat conduction assembly. comprising: a protective film, a graphene heat conduction portion, and a release film; the protective film comprises a PET protective film and an insulating film arranged on the lower surface thereof; the release film comprises a PET release film; and a bonding layer is arranged between the graphene heat conduction portion and the release film. The longitudinal thermal conductivity coefficient of the graphene heat conduction portion prepared via the present invention is 1-15 W / m·K, and a heat conduction assembly is prepared therefrom; the 100°C temperature resistance is reached by the heat conduction assembly; when the heat conduction assembly prepared via the present invention is applied in the field of batteries, the heat conduction assembly has excellent flexibility, the assembly can withstand over 200,000 bends, tensile strength exceeds 20 MPa, elongation at break is 3-10%, and in a reliability test, no change was present on a surface when subject to high temperatures, high humidity, and thermal shock.

Description

A heat conducting component and its application Technical Field

[0001] The present invention belongs to the field of C01B technology, and more specifically relates to a heat conducting component and its application. Background Art

[0002] Graphene materials, or a range of thermal management materials made from graphene, remain popular products on the market. With the rapid development of products like mobile phones and electric vehicles, demand for these products is increasing, and research on these products is on the rise. Faced with the rapid growth of graphene-based products on the market, achieving superior performance, such as high thermal conductivity, high-temperature resistance, and flex resistance, while optimizing processes and controlling costs, remains a crucial task.

[0003] Chinese invention patent CN 116691084 A discloses a graphene thermally conductive film and its preparation method. The patent discloses that the toughness of the thermally conductive film is increased by compounding a resin and glass fiber material with the graphene product. This product, with excellent thermal conductivity, is produced by coating and rolling the flexible substrate surface. However, the resin and other organic compounds in this product are prone to poor weather resistance during high temperatures or long-term use, significantly reducing the performance of the thermally conductive film and affecting its effectiveness.

[0004] Chinese invention patent CN 116835576 A discloses an ultra-soft graphene thermally conductive film with high longitudinal thermal conductivity and a method for preparing the same. The disclosed patent focuses on improving longitudinal thermal conductivity, but the improvement lies in process improvements. It does not address issues such as the temperature resistance of the film material, the effects of thermal shock, and process costs. The overall performance of the graphene thermally conductive film needs to be improved.

[0005] This invention is proposed in order to further study a graphene material that has high thermal conductivity, high temperature resistance, bending resistance and low process cost, and to make it play a better advantage when used in thermal management products such as thermal conductive components. Summary of the Invention

[0006] In order to solve the above technical problems, a first aspect of the present invention provides a heat-conducting assembly, comprising a protective film, a graphene heat-conducting component and a release film;

[0007] The protective film includes a PET protective film and an insulating film arranged on the lower surface thereof; the release film includes a PET release film; and an adhesive layer is provided between the graphene heat-conducting component and the release film.

[0008] In some preferred embodiments, the thickness of the PET protective film, the insulating film and the adhesive layer is 5 to 25 μm, for example, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, etc.

[0009] Preferably, the graphene heat-conducting component is a graphene heat-conducting film or a graphene temperature averaging plate.

[0010] Preferably, the graphene heat-conducting component is obtained by slurry preparation, coating into a raw film, pre-treatment, carbonization, graphitization, and post-treatment.

[0011] In order to further ensure that the defects of the prepared original film are minimal, during the experimental process, the inventors conducted extensive research and found that the viscosity of the slurry is 5000-50000 cP. Preferably, when the viscosity is 8000-20000 cP, internal defects can be avoided during slurry coating, ensuring that the formed original film is more complete, providing a basis for subsequent use as a graphene thermal conductive component.

[0012] In some preferred embodiments, the pretreatment process is performed under the following conditions: gradually raising the temperature to 150-380°C, including a holding period during the heating process, for a total of 24-72 hours, with the heating period lasting 8-24 hours and the holding period lasting 12-48 hours. Because the original film still contains many oxygen-containing functional groups and is in an unstable state, the presence of air during the pretreatment process increases. As the temperature rises, the oxygen-containing functional groups become more active and react with air. If the pretreatment temperature exceeds 380°C, the functional group reaction will be too intense, causing the graphene thermal conductive component to burn.

[0013] In some preferred embodiments, the pH of the slurry is 2-7, for example: 2, 3, 4, 5, 6, 7.

[0014] During the specific experimental process, due to the large amount of slurry and its certain viscosity, maintaining the solid content of the upper and lower surfaces of the slurry as consistent as possible can greatly ensure that the difference in the surface density of the prepared graphene thermal conductive component is greatly reduced. In some preferred embodiments, the solid content of the upper and lower surfaces of the slurry is different, and the difference in solid content between the upper and lower surfaces is 0-3wt%, and is not zero; preferably, the difference in solid content on the upper surface is 0-0.2wt%.

[0015] In some preferred embodiments, the XPS spectrum of the original film satisfies the following conditions: AreaC-O+C=O / (AreaC-C+C=C)≤2.0, where AreaC-O+C=O and AreaC-C+C=C are the peak areas of the sum of the carbon-oxygen single bond and carbon-oxygen double bond and the sum of the carbon-carbon single bond and carbon-carbon double bond in the C 1s peak of the XPS spectrum, respectively. Preferably, AreaC-O+C=O / (AreaC-C+C=C)≤1.9. If AreaC-O+C=O / (AreaC-C+C=C)>2.0, the graphene oxide surface has a large number of oxygen-containing functional groups, resulting in a large number of atomic defects during its carbonization stage. The presence of such defects directly affects heat transfer within the structure, significantly reducing the in-plane thermal conductivity of the micro-nanocavity thermally conductive film.

[0016] In some preferred embodiments, the pretreated sample is GOF-1, and the carbonized sample is GOF-2; (original film mass - GOF-1 mass) ÷ original film mass × 100% is recorded as R GOF-1 , (original film mass - GOF-2 mass) ÷ original film mass × 100% is recorded as R GOF-2 , the mass loss rate R of GOF-1 and GOF-2 satisfies: 7%≤R GOF-2 -R GOF-1 ≤15%; preferably, the mass loss rate R of GOF-1 and GOF-2 satisfies: 8%≤R GOF-2 -R GOF-1 ≤14%.

[0017] In some preferred embodiments, the planar thermal conductivity λ and the thermal diffusion coefficient a of the graphene thermal conductive component satisfy the following relationship: 1.06≤(λ / a-1)*(1100a+750λ) / aλ≤1.91, where λ is only substituted into the value in W / (m·K) unit system for calculation; a is only substituted into the value in mm 2 Calculations are performed using values ​​in the / s unit system.

[0018] In the present invention, if the mass loss rate of the original film is lower during the pretreatment process, it indicates that the carbon conversion rate of the graphene thermal conductive component is higher; however, when the mass loss rate is high during the treatment process, it indicates that the carbon content in the thermal conductive component is higher, and the thermal conductivity of the graphene thermal conductive component is further improved. During the inventor's research, it was found that the sample after pretreatment is GOF-1 and the sample after carbonization is GOF-2. The mass loss rate R of GOF-1 and GOF-2 satisfies: 7%≤R GOF-2 -R GOF-1 ≤15%, especially, the mass loss rate R of GOF-1 and GOF-2 satisfies: 8%≤R GOF-2 -R GOF-1≤14%, which can ensure that the planar thermal conductivity coefficient λ and the thermal diffusion coefficient a of the graphene thermal conductive component meet the following relationship: 1.06≤(λ / a-1)*(1100a+750λ) / aλ≤1.91, taking into account both cost and thermal conductivity, and ensuring that the graphene thermal conductive component has both high temperature resistance of 100°C and thermal shock resistance when used in the thermal conductive component.

[0019] In the present invention, the thickness of the graphene thermal conductive component is obtained by stacking graphene sheets obtained after graphitization. The post-processing step is to stack the graphene thermal conductive component to the desired thickness. The graphene thermal conductive component prepared in the present invention has a highly controllable thickness and can effectively improve the material's heat conduction flux.

[0020] In some preferred embodiments, the graphene heat-conducting component has a thickness of 20 to 1000 μm; preferably, the thickness is 100 to 300 μm.

[0021] In some preferred embodiments, the longitudinal thermal conductivity of the graphene heat-conducting component is 1-15 W / m·K; further preferably, the longitudinal thermal conductivity of the graphene heat-conducting component is 5-10 W / m·K.

[0022] The longitudinal thermal conductivity of the graphene heat-conducting component prepared by the present invention is 1-15 W / m·K, and its heat resistance is greatly improved.

[0023] In some preferred embodiments, PP is used as the coating substrate during the coating process; preferably, the air permeability of the coating substrate is 80-90 cc / min.

[0024] The inventors discovered that the selection of the coating substrate and the determination of the final air permeability in this application are not conventional. Theoretically, it is feasible to select polymer materials similar to PP as the substrate in the art, and it is believed that the air permeability will not affect the final graphene thermal conductive component. However, during the actual research and development process, the inventors encountered the problem that the original film could not be properly peeled from the substrate. To this end, the inventors replaced various substrates, including PET, and ultimately found that when a PP substrate was selected and the air permeability of the PP substrate was guaranteed to be 80-90 cc / min, the original film could be easily peeled from the substrate. The inventors found that the air permeability of the substrate used largely determines the thermal conductivity of the final graphene thermal conductive component. The applicant speculates that the possible reason is that: too high an air permeability can cause slurry seepage problems, which in turn affects the apparent integrity and thermal conductivity stability of the graphene thermal conductive component; however, the inventors also found that too low an air permeability can extend the drying time during the original film preparation process, making it impossible to properly control the drying degree of the original film, resulting in affected original film performance, low production efficiency, high cost and other production problems.

[0025] In some preferred embodiments, the carbonization temperature is 900-1400°C; preferably, the graphitization temperature is 2000-3300°C.

[0026] In some preferred embodiments, the surface density of the graphene thermal conductive component is 3.6-2200 mg / cm 2 .

[0027] In some preferred embodiments, the specific preparation method of the graphene thermal conductive component is as follows:

[0028] 1) Slurry preparation: Graphene oxide cake was added to a disperser and dispersed at a low speed of 40 r / min and a high speed of 1500 r / min for more than 30 min, followed by a low speed of 100 r / min and a high speed of 3000 r / min for more than 180 min to obtain a slurry;

[0029] 2) The slurry obtained in 1) is homogenized and defoamed, and then placed on a coating machine for coating. The substrate is placed and the coating gap is 2-4 mm. The coated graphene oxide film is then dried in an oven (50-70°C) to obtain the original film;

[0030] 3) Pretreatment: Gradually raise the temperature to 150-380°C, including a holding period during the heating process, which takes 24-72 hours, including 8-24 hours for the heating period and 12-48 hours for the holding period;

[0031] 4) Carbonization: The carbonization temperature is 900-1400°C, the carbonization time is 18-32 hours, the carbonization heating time is 8-12 hours, and the cooling time is 10-20 hours;

[0032] 5) Graphitization: The graphitization temperature is 2000-3300°C, the highest graphitization temperature is 3300°C, the heating time is 17-20 hours, the holding time is 1-3 hours, and the cooling time is 24-72 hours;

[0033] 6) Post-processing: The product obtained after graphitization is subjected to calendering and stacking to obtain a graphene thermal conductive component of the required thickness.

[0034] A second aspect of the present invention provides a heat dissipation system including the above-mentioned heat conduction component.

[0035] The third aspect of the present invention provides an application of a thermal conductive component in the fields of aerospace, communication equipment, electric vehicles, energy storage batteries, and 5G base stations.

[0036] Beneficial effects: Compared with the existing technology, the present invention has the following advantages:

[0037] 1) The graphene thermal conductive component prepared by the present invention satisfies the following two conditions simultaneously: the sample after pretreatment is GOF-1, and the sample after carbonization is GOF-2; the mass loss rate R of GOF-1 and GOF-2 satisfies: 7%≤R GOF-2 -R GOF-1 ≤15%, the relationship between the planar thermal conductivity λ and the thermal diffusion coefficient a satisfies the following: 1.06≤(λ / a-1)*(1100a+750λ) / aλ≤1.91, taking into account both cost and thermal conductivity, ensuring that the graphene thermal conductive component can withstand high temperatures of 300°C and thermal shock when used in thermal conductive components;

[0038] 2) The graphene thermal conductive component prepared by the present invention uses PP as a coating substrate. The coating substrate has an air permeability of 80-90 cc / minute, ensuring that the original film can be smoothly peeled from the substrate surface, reducing the process cost during the preparation process and ensuring that the prepared thermal conductive component costs 20%-30% less than conventional PET substrates;

[0039] 4) When used in the battery field, the thermal conductive component prepared by the present invention has excellent flexibility, can withstand bending times greater than 200,000 times, has a tensile strength exceeding 20 MPa, and an elongation at break of 3-10%. In reliability tests, the surface remains unchanged after high temperature, high humidity, and hot and cold shocks. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] FIG1 is an XPS test chart of the original film of Example 1;

[0041] FIG2 is an XRD test diagram of the original film of Example 1;

[0042] FIG3 is an XPS test graph of the graphene thermal conductive film of Example 1;

[0043] FIG4 is an XRD test diagram of the graphene thermal conductive film of Example 1;

[0044] FIG5 is a comparison diagram of the heat-conducting component prepared in Example 1 before and after undergoing a temperature tolerance test;

[0045] FIG6 is a graph showing the result of a voltage withstand test of the heat conductive component prepared in Example 1;

[0046] FIG7 is a schematic structural diagram of the heat-conducting component of the present invention, in which: 1-PET protective film; 2-insulating film; 3-graphene heat-conducting component; 4-adhesive layer; 5-release film. DETAILED DESCRIPTION

[0047] In the present invention, the X-ray diffraction was performed using a Japanese Rigaku Ultima IV, a copper target, a scanning range of 5-90 degrees, and a scanning speed of 10° / min.

[0048] XPS (X-ray photoelectron spectroscopy) was performed using an ESCA lab 250 XPS instrument. The sample was placed at a base pressure of 3 × 10 -8 In the Pa energy analysis mode, A1 Kα 1486.8eV X-rays were used as the excitation source to test the chemical composition of the samples.

[0049] In the present invention, the planar thermal conductivity is measured using a NETZSCH LFA 467 device and tested in accordance with the "Q / GDMR04-2023" standard. Example

[0050] As shown in Figure 5, a heat-conducting component includes a protective film, a graphene heat-conducting component and a release film; the protective film includes a PET protective film 1 and an insulating film 2 arranged on its lower surface; the graphene heat-conducting component 3 is a graphene heat-conducting film; the release film 5 is a PET release film; an adhesive layer 4 is provided between the graphene heat-conducting component 3 and the release film 5, and the adhesive layer is a double-sided tape.

[0051] The thickness of the PET protective film and the double-sided tape is 10 μm.

[0052] The specific preparation method of the graphene thermal conductive film is as follows:

[0053] 1) Slurry preparation: Graphene oxide cake was added to a disperser and dispersed at a low speed of 40 r / min and a high speed of 1500 r / min for more than 30 min, followed by a low speed of 100 r / min and a high speed of 3000 r / min for more than 180 min to obtain a slurry;

[0054] 2) The slurry obtained in 1) was homogenized and defoamed, and then coated on a coating machine. The substrate was placed, and the coating gap was 2-4 mm. The coated graphene oxide film was then dried in an oven (50-70°C) to obtain a raw film. The XPS and XRD characterization results of the raw film are shown in Figures 1 and 2.

[0055] 3) Pretreatment: Gradually increase the temperature to 150~380℃, including a heat preservation stage, for a total of 24~72 hours.

[0056] 4) Carbonization: The carbonization temperature is 900-1400° C. and the carbonization time is 24 hours;

[0057] 5) Graphitization: The graphitization temperature is 2000-3300° C., and the graphitization time is 44 hours;

[0058] 6) Post-processing: The product obtained after graphitization is calendered and stacked to obtain a graphene thermal conductive film with a thickness of 40-400 μm.

[0059] The substrate in step 2) is a PP substrate with an air permeability of 80-90 cc / min, and is sold by any manufacturer.

[0060] The parameters and test results of Examples 1 to 10 are shown in Tables 1 and 2;

[0061] The pretreatment temperature in Examples 1 to 8 is all 280° C., the heating time accounts for 1 / 3 of the total time, and the holding time accounts for 2 / 3.

[0062] In Examples 9 and 10, the pretreatment temperature is 340° C., the heating time accounts for 1 / 3 of the total time, and the holding time accounts for 2 / 3.

[0063] Table 1:

[0064]

[0065] Table 2:

[0066]

[0067] In Examples 1 to 3, when AreaC-O+C=O / (AreaC-C+C=C) is about 1.9, the internal oxygen content is high, and the pretreatment time needs to be further extended to release the internal oxygen to prevent it from reacting during the carbonization process at around 1200°C, thereby reducing the R rate, increasing the carbon yield, and reducing costs.

[0068] Compared with Example 1, when the AreaC-O+C=O / (AreaC-C+C=C) of the original graphene oxide film is about 1.6, its internal oxygen content is low. Under the same pretreatment time, the R rate can be reduced, the carbon yield can be increased, and the cost can be reduced. However, due to the low oxygen content of graphene oxide (GO) (AreaC-O+C=O / (AreaC-C+C=C)=1.6), the degree of lamellae exfoliation is low, the self-assembly effect of the original graphene film is poor, and the thermal conductivity coefficient is low.

[0069] Compared with Example 4, Example 5 increases the graphitization temperature and improves the thermal conductivity;

[0070] The performance of the product obtained in Example 6 is the best.

[0071] In Examples 7-8, the original graphene oxide film AreaC-O+C=O / (AreaC-C+C=C)>2.0. Even though it has the same process parameters as Examples 1-2 and 4-5, its planar thermal conductivity is significantly reduced. This is because the original film surface contains a large number of oxygen-containing functional groups, which produce a large number of atomic defects during its carbonization stage. The presence of such defects will directly affect the transfer of heat in its structure.

[0072] Comparing Examples 9-10 with Examples 1-2, the pretreatment temperature is increased, the ash content is reduced during the carbonization process, and a membrane product with similar thermal conductivity can be obtained with a shorter carbonization time. The R rate is reduced, the carbon yield is increased, and the cost is reduced.

[0073] The thermally conductive films prepared in Examples 1-6 and 9-10 were assembled into a thermally conductive assembly and performance tests were performed. The specific test contents and test results are shown in Table 3:

[0074] in:

[0075] 1) Tensile strength test: In a standard laboratory environment, refer to GB / T 1040.3-2006, use a special die and die-cutting tooling to prepare a 150mm*10mm strip sample. After tightening with a tensile fixture, use a universal tensile testing machine to test the tensile strength of the graphite film. The tensile rate is 10mm / min, and the test is carried out in the XY direction. The minimum value is required to be ≥20MPa.

[0076] 2) Peel force test: Refer to GB / T 2792-2014 Test method for 180° peel strength of pressure-sensitive adhesive tapes, and the minimum value is required to be ≥6N / 25mm.

[0077] 3) Temperature Resistance Test: Samples of the thermally conductive components prepared in Examples 1-6, measuring 25 mm by 35 mm, were baked in a watch glass at 100°C for 10 days. The samples were observed for cracking, powdering, or embrittlement. After high-temperature baking, if no cracking or powdering was observed on the surface, and if no embrittlement was observed when the film was pinched by hand, the surface met the long-term temperature resistance requirement and was scored as OK. Otherwise, it was scored as NO.

[0078] 4) Withstand voltage test: In a standard laboratory environment, refer to GB1408.1-2006 for testing. Sample size is 100mm×100mm×thickness. Use an insulation withstand voltage tester (from 100V to 1000V, voltage rate 100V / s, AC setting). Set the leakage current to 0.5mA. Maintain the voltage at 1000V for 1 minute. The leakage current must be ≤0.5mA.

[0079] 5) Thermal shock test: Refer to the standard GB / T 2423.22 (Basic environmental test procedures for electrical and electronic products Test N: Temperature change test method). Before the test, there should be no bubbles or wrinkles on the surface of the mounted sample. After the test, the bubble size should not exceed 5.5mm; the wrinkle length should not exceed 5mm; the bubble and wrinkle height should not exceed 0.05mm. This is marked as OK, otherwise it is marked as NO.

[0080] The specific test methods are as follows:

[0081] Take the finished shapes die-cut in Examples 1 to 6, take 100 μm die-cut samples (if there is no fixed die-cut shape, take a 50 mm*50 mm die-cut sample) and test the test samples according to GB / T 2423.22 (Basic environmental testing procedures for electrical and electronic products, Test N: Temperature change test method).

[0082] TH (test temperature): 70℃±2℃

[0083] TL (test temperature): -40℃±2℃

[0084] tc1 (stabilization time after temperature switching): 5 min

[0085] tc2 (sample TH temperature stabilization time): 1h

[0086] tc3 (sample TL temperature stabilization time): 1h

[0087] T (number of cycles): 24 cycles (48h)

[0088] Test after returning to normal temperature.

[0089] After the test, there should be no obvious defects in appearance, no bubbles, wrinkles, etc.

[0090] Table 3:

[0091]

[0092] The effects of Examples 7 and 8 were relatively poor, and no tests related to the thermal conductive components were performed.

Claims

1. A heat conducting component, characterized in that: Including a protective film, a graphene heat-conducting component and a release film; The protective film comprises a PET protective film and an insulating film arranged on the lower surface thereof; the release film comprises a PET release film; and a bonding layer is arranged between the graphene heat-conducting component and the release film; The graphene heat-conducting component is obtained through slurry preparation, coating into an original film, pretreatment, carbonization, graphitization and post-treatment.

2. The heat conducting component according to claim 1, characterized in that: The operating conditions of the pretreatment are: gradually raising the temperature to 150-380° C., and the heating process also includes a heat preservation stage, wherein the heating stage is 8-24 hours and the heat preservation stage is 12-48 hours.

3. The heat conducting component according to claim 2, characterized in that: The sample after pretreatment is GOF-1, and the sample after carbonization is GOF-2; the mass loss rate R of GOF-1 and GOF-2 satisfies: 7%≤R GOF-2 -R GOF-1 ≤15%; preferably, the mass loss rate R of GOF-1 and GOF-2 satisfies: 8%≤R GOF-2 -R GOF-1 ≤14%.

4. The heat conducting component according to claim 3, characterized in that: The XPS spectrum of the original film satisfies: AreaC-O+C=O / (AreaC-C+C=C)≤2.0, AreaC-O+C=O and AreaC-C+C=C are respectively the peak areas of the sum of the carbon-oxygen single bond and the carbon-oxygen double bond of C 1s and the sum of the carbon-carbon single bond and the carbon-carbon double bond in the XPS spectrum, preferably, AreaC-O+C=O / (AreaC-C+C=C)≤1.

9.

5. The heat conducting assembly according to claim 1, characterized in that: The slurry viscosity is 5000-50000 cP; preferably, the viscosity is 8000-20000 cP.

6. The heat conducting component according to claim 4 or 5, characterized in that: The solid contents of the upper and lower surfaces of the slurry are different, and the difference in solid contents between the upper and lower surfaces is 0-3wt% and is not 0; preferably, the difference in solid content between the upper surfaces is 0-0.2wt% and is not 0.

7. The heat conducting component according to claim 1, characterized in that: The graphene heat-conducting component has a thickness of 20-1000 μm; preferably, the thickness is 100-300 μm.

8. The heat conducting assembly according to claim 1, characterized in that: The longitudinal thermal conductivity of the graphene heat-conducting component is 1-15 W / m·K.

9. The heat conducting component according to claim 1, characterized in that: PP is used as the coating substrate during the coating process; preferably, the air permeability of the coating substrate is 80-90 cc / min.

10. The heat conducting component according to claim 1, characterized in that: The carbonization temperature is 900-1400°C; preferably, the graphitization temperature is 2000-3300°C.

11. The heat conducting component according to claim 1 or 10, characterized in that: The numerical values ​​of the planar thermal conductivity λ and the thermal diffusion coefficient a of the graphene thermal conductive component satisfy the following relationship: 1.06≤(λ / a-1)*(1100a+750λ) / aλ≤1.91, where λ is only substituted into the value in W / (m·K) unit system for calculation; a is only substituted into the value in mm 2 / s unit system for calculation.

12. A heat dissipation system, characterized in that: A heat-conducting component comprising any one of claims 1 to 11.

13. An application of the thermal conductive component according to any one of claims 1 to 11 in the fields of aerospace, communication equipment, electric vehicles, energy storage batteries, and 5G base stations.

Images