High-thermal-conductivity graphite calendering release film and preparation method thereof

Abstract

The invention relates to the technical field of release films, in particular to a high-thermal-conductivity graphite calendering release film and a preparation method thereof. The high-thermal-conductivity graphite calendering release film comprises a base material layer and a release layer adhered to the surface of the base material layer, the release layer is prepared from the following materials in parts by weight: 30 to 35 parts of dimethyl silicone oil, 25 to 30 parts of organic silicon resin, 20 to 26 parts of modified composite heat-conducting filler, 0.5 to 1 part of defoaming agent, 0.2 to 0.5 part of flatting agent, 30 to 34 parts of butanone and 1 to 3 parts of hydrogen-containing silicone oil; wherein the modified composite heat-conducting filler is prepared by the following steps: firstly, chemically grafting the composite heat-conducting filler by utilizing a silane coupling agent, and then coating by utilizing polydopamine. According to the high-thermal-conductivity graphite calendered release film prepared in the invention, the thermal conductivity and processability of the release film are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of release films, and particularly to a high thermal conductivity graphite calendered release film and a preparation method thereof. Background Art

[0002] With the development trend of integration and high power of modern electronic products, the heat dissipation problem has increasingly become a key factor restricting the performance of electronic products. Traditional heat dissipation materials such as metal radiators and silica gels have limited thermal conductivity and stability, and it is difficult to meet the high requirements of current electronic products for heat dissipation materials. As a new type of heat dissipation material, high thermal conductivity graphite film has gradually emerged in the field of electronic heat dissipation due to its excellent thermal conductivity, high temperature stability and good processing performance.

[0003] The high thermal conductivity graphite calendered release film is a thin film material prepared from natural flake graphite or synthetic graphite as raw materials through a specific calendering process. This film has the characteristics of high thermal conductivity, good flexibility and easy processing, can closely adhere to the surface of electronic components, effectively transfer heat, reduce the temperature of components, and improve the stability and service life of electronic products.

[0004] Although high thermal conductivity graphite film has significant advantages in the field of heat dissipation, there are still some problems in the existing preparation methods. On the one hand, the traditional pyrolytic deposition method for preparing highly oriented graphite film needs to be carried out under high temperature and high pressure, with a long production cycle and high cost, which limits its wide application. On the other hand, although the graphite film prepared by chemical vapor deposition (CVD) technology has good thermal conductivity, the process is complex, and it is difficult to prepare graphite films with large area and uniform thickness. In addition, the existing graphite films are prone to problems such as cracks and wrinkles during the processing, which affect their thermal conductivity and aesthetics. Based on this, the present invention provides a high thermal conductivity graphite calendered release film and a preparation method thereof. Summary of the Invention

[0005] The purpose of the present invention is to provide a high thermal conductivity graphite calendered release film and a preparation method thereof, which improve the thermal conductivity and processing performance.

[0006] In the first aspect, the present invention provides a high thermal conductivity graphite calendered release film, including a substrate layer and a release layer adhered to the surface of the substrate layer; the release layer is composed of the following materials in parts by weight: 30 - 35 parts of dimethyl silicone oil, 25 - 30 parts of silicone resin, 20 - 26 parts of modified composite thermal conductive filler, 0.5 - 1 part of defoaming agent, 0.2 - 0.5 part of leveling agent, 30 - 34 parts of methyl ethyl ketone, and 1 - 3 parts of hydrogen-containing silicone oil; wherein, the modified composite thermal conductive filler includes chemically grafting the composite thermal conductive filler with a silane coupling agent first, and then coating it with polydopamine.

[0007] Further, the thickness of the base material layer is 10 - 12 μm, and the preparation steps include: mixing silicon carbide, graphene and ethanol, adding polyvinylpyrrolidone, centrifuging after ultrasonic dispersion, and retaining the upper stable suspension; soaking the polyimide film in a 0.5 - 1% NaOH solution by mass for 5 - 10 minutes, cleaning and drying; dropping the suspension onto the surface of the polyimide film, spin-coating at a low speed of 500 - 1000 rpm for 10 - 12 seconds, then increasing to a high speed of 2000 - 3000 rpm and spin-coating for 30 - 35 seconds, controlling the film thickness to be 100 - 200 nm, drying at 60 - 70 °C for 1 - 2 h, heating to 120 - 140 °C at a rate of 4 - 6 °C / min, holding for 30 - 40 min, and continuing to heat to 180 - 200 °C at a rate of 8 - 10 °C / min and holding for 1 - 2 hours to obtain the product.

[0008] Further, the dosage ratio of the silicon carbide, graphene, ethanol and polyvinylpyrrolidone is (2 - 4) g : (0.5 - 1.5) g : (800 - 900) mL : (0.2 - 0.4) g.

[0009] Further, the composite heat-conducting filler includes hexagonal boron nitride, alumina and carbon nanotubes with a weight ratio of (15 - 20) : (8 - 12) : (3 - 5).

[0010] Further, the particle size of the alumina is 20 - 50 nm, and the average diameter of the carbon nanotubes is 9 - 11 nm.

[0011] Further, the preparation method of the modified composite heat-conducting filler includes: dissolving dopamine hydrochloride in Tris buffer solution, adding the composite heat-conducting filler grafted with a silane coupling agent, forming a uniform dispersion after ultrasonic treatment, adding H2O2 to initiate oxidative polymerization, stirring at a constant temperature of 25 - 30 °C for 3 - 4 h, centrifuging after the reaction ends, washing with deionized water until neutral and then drying to obtain the product.

[0012] Further, the dosage ratio of the composite heat-conducting filler grafted with a silane coupling agent, dopamine hydrochloride, Tris buffer solution and H2O2 is 100 g : (0.5 - 1.5) g : (400 - 500) mL : (0.1 - 0.2) g, and the pH of the Tris buffer solution is 8.5.

[0013] Further, the preparation method of the composite heat-conducting filler grafted with a silane coupling agent includes: dispersing the composite heat-conducting filler in a mixed solution of ethanol and water, ultrasonic treating for 30 min to form a uniform suspension, adding glacial acetic acid to adjust the pH to 4 - 5, and stirring for 10 - 15 min; dropping KH-550 into the suspension, stirring and reacting at a constant water bath temperature of 60 - 70 °C for 3 - 4 h, centrifuging, washing and drying after the reaction to obtain the product.

[0014] Furthermore, the weight ratio of the composite thermal conductive filler, ethanol, water and KH-550 is 100:(20 - 30):(4 - 6):(2 - 3).

[0015] In a second aspect, the present invention provides a method for preparing a highly thermally conductive graphite calendered release film, the steps comprising: ultrasonically mixing dimethyl silicone oil, silicone resin, modified composite thermal conductive filler, defoaming agent, leveling agent, methyl ethyl ketone and hydrogen-containing silicone oil in a formula amount uniformly, standing for defoaming to obtain a release agent; coating the release agent on a substrate layer by a microgravure coating method, with a coating speed of 20 - 30 m / min, and obtaining the product after curing.

[0016] The beneficial effects of the present invention are as follows:

[0017] In the present invention, the double modification of the composite thermal conductive filler is utilized, and the composite thermal conductive filler is chemically grafted by a silane coupling agent, enhancing the interfacial bonding force between the filler and the silicone resin matrix. This chemical bonding not only improves the dispersibility and stability of the filler, but also optimizes the peel strength, abrasion resistance and hydrophobicity of the release film. On the basis of the silane coupling agent grafting, polydopamine is used for coating, further enhancing the interfacial compatibility and stability of the filler. The adhesiveness and biocompatibility of polydopamine enable it to tightly wrap on the surface of the filler, forming a protective barrier to prevent the filler from agglomerating or falling off during processing and use.

[0018] The present invention utilizes the synergistic effect of the composite thermal conductive filler. By mixing hexagonal boron nitride, alumina and carbon nanotubes in a certain proportion, an efficient three-dimensional thermal conductive network is constructed. Hexagonal boron nitride (high in-plane thermal conductivity), nano-spherical alumina (filling gaps) and one-dimensional carbon nanotubes (bridging thermal conduction paths) are used to construct a three-dimensional thermal conductive network through the gradient distribution of particle size and morphology, breaking through the percolation threshold limit of traditional single fillers. In the system of the present invention, the absence of any one filler results in a significant decrease in thermal conductivity (such as a 35% decrease when boron nitride is missing), proving the structural complementarity that none of the three can be missing.

[0019] In the present invention, the substrate layer is coated with a silicon carbide / graphene composite material on the surface of the polyimide film, which not only improves the bonding force between the substrate and the release layer, but also significantly enhances the thermal conductivity of the release film. The high thermal conductivity of silicon carbide and graphene enables heat to be quickly transferred through the substrate layer to the release layer, thereby improving the thermal conduction efficiency of the entire release film.

[0020] The present invention also combines low-speed (500-1000rpm) and high-speed (2000-3000rpm) spin coating to ensure that the silicon carbide / graphene nanolayer uniformly covers the polyimide substrate to form a strong bonding interface. The temperature is stepped up (4-10℃ / min) to 180-200℃ to promote the formation of graphitized structure, improve thermal conductivity and mechanical strength; when not coated, the thermal conductivity is only 0.14W / m·K, and the flexibility is >1000 times. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] It should be noted that the dimethyl silicone oil model in the present invention is PMX-200; the silicone resin model is SilresSREN 80; the defoamer model is C12E3; the leveling agent model is PAA-Na 1200; the hydrogen-containing silicone oil model is RH-H503; the hexagonal boron nitride model is h-BN, CAS No.: 10043-11-5; and the graphene is a few-layer graphene purchased from Xi'an Qiyue Biotechnology Co., Ltd.

[0023] Example 1

[0024] The present embodiment provides a high thermal conductivity graphite calendered release film, comprising a substrate layer and a release layer bonded to the surface of the substrate layer; the release layer is composed of the following materials in parts by weight: 32 parts of dimethyl silicone oil, 27 parts of silicone resin, 23 parts of modified composite thermal conductive filler, 0.7 parts of defoaming agent, 0.3 parts of leveling agent, 32 parts of butanone and 2 parts of hydrogen-containing silicone oil; wherein the modified composite thermal conductive filler comprises chemically grafting the composite thermal conductive filler with a silane coupling agent and then coating it with polydopamine.

[0025] Among them, the thickness of the substrate layer is 11 μm, and the preparation steps include: mixing silicon carbide, graphene and ethanol, adding polyvinylpyrrolidone, treating in an ultrasonic instrument at a power of 90 W for 75 minutes to ensure uniform dispersion of the particles, centrifuging at 5000 rpm for 15 minutes to remove the undispersed agglomerated particles, and retaining the stable suspension on the upper layer; soaking the polyimide film in a 0.7% NaOH solution by mass for 7 minutes, washing with deionized water and drying; dropping the suspension onto the surface of the polyimide film, spin-coating at a low speed of 750 rpm for 11 seconds, and then increasing the speed to 2500 rpm for high-speed spin-coating for 32 seconds to control the film thickness to 150 nm. After drying at 65 °C for 1.5 h, heating to 130 °C at a rate of 5 °C / min, holding for 35 min, and continuing to heat to 190 °C at a rate of 9 °C / min, and holding for 1.5 hours to obtain; the dosage ratio of silicon carbide, graphene, ethanol and polyvinylpyrrolidone is 3 g: 1 g: 850 mL: 0.3 g; the particle size of silicon carbide is 10 - 50 nm;

[0026] The preparation method of the modified composite thermal conductive filler includes: dispersing the composite thermal conductive filler in a mixed solution of ethanol and water, performing ultrasonic treatment for 30 min to form a uniform suspension, adding glacial acetic acid to adjust the pH to 4.5, and stirring for 12 min; dropping KH-550 into the suspension, and stirring and reacting at 65 °C under a constant temperature water bath condition for 3.5 h. After the reaction, centrifuging, washing with deionized water and drying to obtain the composite thermal conductive filler grafted with a silane coupling agent; the weight part ratio of the composite thermal conductive filler, ethanol, water and KH-550 is 100: 25: 5: 2.5;

[0027] Among them, the composite thermal conductive filler includes hexagonal boron nitride, alumina and carbon nanotubes with a weight part ratio of 17: 10: 4; the particle size of the alumina is 20 - 50 nm, and the average diameter of the carbon nanotubes is 10 nm;

[0028] Dissolve dopamine hydrochloride in Tris buffer solution, add the composite thermal conductive filler grafted with a silane coupling agent, and form a uniform dispersion liquid after ultrasonic treatment. Add H2O2 to initiate oxidative polymerization, stir at a constant temperature of 27 °C for 3.5 h. After the reaction, centrifuge, wash with deionized water until neutral and then dry to obtain; the dosage ratio of the composite thermal conductive filler grafted with a silane coupling agent, dopamine hydrochloride, Tris buffer solution and H2O2 is 100 g: 1 g: 450 mL: 0.15 g, and the pH of the Tris buffer solution is 8.5;

[0029] The preparation method of this high thermal conductivity graphite calendered release film includes the steps of: ultrasonically mixing the formula amounts of dimethyl silicone oil, silicone resin, modified composite thermal conductive filler, defoaming agent, leveling agent, methyl ethyl ketone and hydrogen-containing silicone oil evenly, standing for defoaming to obtain a release agent; coating the release agent on the substrate layer by a microgravure coating method, with a coating speed of 25 m / min and a release layer thickness of 3.5 μm, and curing to obtain.

[0030] Example 2

[0031] This example provides a high - thermal - conductivity graphite calendered release film, which includes a substrate layer and a release layer adhered to the surface of the substrate layer; the release layer is composed of the following materials in parts by weight: 30 parts of dimethyl silicone oil, 25 parts of silicone resin, 20 parts of modified composite thermal - conductive filler, 0.5 part of defoaming agent, 0.2 part of leveling agent, 30 parts of methyl ethyl ketone, and 1 part of hydrogen - containing silicone oil; among them, the modified composite thermal - conductive filler includes chemically grafting the composite thermal - conductive filler with a silane coupling agent first, and then coating it with polydopamine.

[0032] Among them, the thickness of the substrate layer is 11 μm, and the preparation steps include: mixing silicon carbide, graphene, and ethanol, adding polyvinylpyrrolidone, treating in an ultrasonic instrument at a power of 80 W for 60 minutes to ensure uniform dispersion of particles, centrifuging at 4000 rpm for 15 minutes to remove undispersed agglomerated particles, and retaining the upper - layer stable suspension; soaking the polyimide film in a 0.5% NaOH solution by mass for 5 minutes, washing with deionized water and drying; dropping the suspension onto the surface of the polyimide film, spin - coating at a low speed of 500 rpm for 10 seconds, then increasing the speed to 2000 rpm and spin - coating at a high speed for 30 seconds, controlling the film thickness to be 100 nm, drying at 60 °C for 1 h, then heating to 120 °C at a rate of 4 °C / min, holding for 30 min, and continuing to heat to 180 °C at a rate of 8 °C / min and holding for 1 hour to obtain it; the dosage ratio of silicon carbide, graphene, ethanol, and polyvinylpyrrolidone is 2 g:0.5 g:800 mL:0.2 g; the particle size of silicon carbide is 10 - 50 nm;

[0033] The preparation method of the modified composite thermal - conductive filler includes: dispersing the composite thermal - conductive filler in a mixed solution of ethanol and water, ultrasonic - treating for 30 min to form a uniform suspension, adding glacial acetic acid to adjust the pH to 4, and stirring for 10 min; dropping KH - 550 into the suspension, stirring and reacting at a constant temperature of 60 °C in a water bath for 3 h, and after the reaction, centrifuging, washing with deionized water, and drying to obtain the composite thermal - conductive filler grafted with a silane coupling agent; the weight - part ratio of the composite thermal - conductive filler, ethanol, water, and KH - 550 is 100:20:4:2;

[0034] Among them, the composite thermal - conductive filler includes hexagonal boron nitride, alumina, and carbon nanotubes with a weight - part ratio of 15:8:3; the particle size of the alumina is 20 - 50 nm, and the average diameter of the carbon nanotubes is 10 nm;

[0035] Dissolve dopamine hydrochloride in Tris buffer solution, add the composite thermal conductive filler grafted with silane coupling agent, and form a uniform dispersion after ultrasonic treatment. Add H2O2 to initiate oxidative polymerization, stir at a constant temperature of 25 °C for 3 h, centrifuge after the reaction ends, wash with deionized water until neutral, and then dry to obtain; the dosage ratio of the composite thermal conductive filler grafted with silane coupling agent, dopamine hydrochloride, Tris buffer solution and H2O2 is 100 g: 0.5 g: 400 mL: 0.1 g, and the pH of the Tris buffer solution is 8.5;

[0036] The preparation method of this high-thermal-conductivity graphite calendered release film includes the following steps: ultrasonically mix the formulated amount of dimethyl silicone oil, silicone resin, modified composite thermal conductive filler, defoaming agent, leveling agent, methyl ethyl ketone and hydrogen-containing silicone oil evenly, and let it stand for defoaming to obtain a release agent; coat the release agent on the substrate layer by microgravure coating method, with a coating speed of 20 m / min and a release layer thickness of 3.5 μm, and obtain it after curing.

[0037] Example 3

[0038] This example provides a high-thermal-conductivity graphite calendered release film, which includes a substrate layer and a release layer adhered to the surface of the substrate layer; the release layer is composed of the following materials in parts by weight: 35 parts of dimethyl silicone oil, 30 parts of silicone resin, 26 parts of modified composite thermal conductive filler, 1 part of defoaming agent, 0.5 part of leveling agent, 34 parts of methyl ethyl ketone and 3 parts of hydrogen-containing silicone oil; among them, the modified composite thermal conductive filler includes chemically grafting the composite thermal conductive filler with a silane coupling agent first, and then coating it with polydopamine.

[0039] Among them, the thickness of the substrate layer is 11 μm, and the preparation steps include: mix silicon carbide and graphene with ethanol, add polyvinylpyrrolidone, and treat it in an ultrasonic instrument at a power of 100 W for 90 minutes to ensure uniform dispersion of the particles, centrifuge at 6000 rpm for 15 minutes, remove the undispersed agglomerated particles, and retain the upper stable suspension; soak the polyimide film in a 1% NaOH solution by mass fraction for 10 minutes, wash it with deionized water and then dry it; drop the suspension on the surface of the polyimide film, spin-coat it at a low speed of 1000 rpm for 12 seconds, and then increase the speed to 3000 rpm for high-speed spin-coating for 35 seconds, control the film thickness to be 200 nm, dry it at 70 °C for 2 h, then heat it up to 140 °C at a rate of 6 °C / min, keep it warm for 40 min, and continue to heat it up to 200 °C at a rate of 10 °C / min and keep it warm for 2 hours to obtain; the dosage ratio of silicon carbide, graphene, ethanol and polyvinylpyrrolidone is 4 g: 1.5 g: 900 mL: 0.4 g; the particle size of silicon carbide is 10 - 50 nm;

[0040] The preparation method of the modified composite heat-conducting filler includes: dispersing the composite heat-conducting filler in a mixed solution of ethanol and water, performing ultrasonic treatment for 30 min to form a uniform suspension, adding glacial acetic acid to adjust the pH to 5, and stirring for 15 min; dropping KH-550 into the suspension, and stirring and reacting for 4 h under the condition of a constant-temperature water bath at 70 °C. After the reaction, centrifugation is carried out, and after washing and drying with deionized water, the composite heat-conducting filler grafted with a silane coupling agent is obtained; the weight ratio of the composite heat-conducting filler, ethanol, water, and KH-550 is 100:30:6:3;

[0041] Among them, the composite heat-conducting filler includes hexagonal boron nitride, alumina, and carbon nanotubes with a weight ratio of 20:12:5; the particle size of the alumina is 20 - 50 nm, and the average diameter of the carbon nanotubes is 10 nm;

[0042] Dissolve dopamine hydrochloride in Tris buffer solution, add the composite heat-conducting filler grafted with a silane coupling agent, and form a uniform dispersion after ultrasonic treatment. Add H2O2 to initiate oxidative polymerization, and stir at a constant temperature of 30 °C for 4 h. After the reaction, centrifugation is carried out, and after washing with deionized water until neutral and then drying, the product is obtained; the dosage ratio of the composite heat-conducting filler grafted with a silane coupling agent, dopamine hydrochloride, Tris buffer solution, and H2O2 is 100 g:1.5 g:500 mL:0.2 g, and the pH of the Tris buffer solution is 8.5;

[0043] The preparation method of this high-heat-conducting graphite calendered release film includes the steps of: ultrasonically mixing the formula amounts of dimethyl silicone oil, silicone resin, modified composite heat-conducting filler, defoaming agent, leveling agent, methyl ethyl ketone, and hydrogen-containing silicone oil evenly, and standing for defoaming to obtain a release agent; coating the release agent on the substrate layer by means of microgravure coating, with a coating speed of 30 m / min and a release layer thickness of 3.5 μm, and obtaining the product after curing.

[0044] Example 4

[0045] This example provides a high-heat-conducting graphite calendered release film, which includes a substrate layer and a release layer adhered to the surface of the substrate layer; the release layer is composed of the following materials in parts by weight: 30 parts of dimethyl silicone oil, 30 parts of silicone resin, 20 parts of modified composite heat-conducting filler, 1 part of defoaming agent, 0.2 part of leveling agent, 34 parts of methyl ethyl ketone, and 1 part of hydrogen-containing silicone oil; among them, the modified composite heat-conducting filler includes chemically grafting the composite heat-conducting filler with a silane coupling agent first, and then coating it with polydopamine.

[0046] Among them, the thickness of the substrate layer is 11 μm, and the preparation steps include: mixing silicon carbide, graphene and ethanol, adding polyvinylpyrrolidone, treating in an ultrasonic instrument at a power of 80 W for 90 minutes to ensure uniform dispersion of the particles, centrifuging at 4000 rpm for 15 minutes to remove the undispersed agglomerated particles, and retaining the upper stable suspension; soaking the polyimide film in a 1% NaOH solution by mass for 5 minutes, washing with deionized water and drying; dropping the suspension onto the surface of the polyimide film, spin-coating at a low speed of 1000 rpm for 10 seconds, and then increasing to a high speed of 2000 rpm for spin-coating for 35 seconds, controlling the film thickness to be 100 nm, drying at 70 °C for 1 h, heating to 120 °C at a rate of 6 °C / min, holding for 40 min, and continuing to heat to 200 °C at a rate of 8 °C / min and holding for 1 hour to obtain; the dosage ratio of silicon carbide, graphene, ethanol and polyvinylpyrrolidone is 4 g: 0.5 g: 900 mL: 0.2 g; the particle size of silicon carbide is 10 - 50 nm;

[0047] The preparation method of the modified composite thermal conductive filler includes: dispersing the composite thermal conductive filler in a mixed solution of ethanol and water, performing ultrasonic treatment for 30 min to form a uniform suspension, adding glacial acetic acid to adjust the pH to 5, and stirring for 10 min; dropping KH-550 into the suspension, stirring and reacting at a constant temperature of 60 °C in a water bath for 4 h, and after the reaction, centrifuging, washing with deionized water and drying to obtain the composite thermal conductive filler grafted with a silane coupling agent; the weight part ratio of the composite thermal conductive filler, ethanol, water and KH-550 is 100: 20: 6: 2;

[0048] Among them, the composite thermal conductive filler includes hexagonal boron nitride, alumina and carbon nanotubes with a weight part ratio of 15: 12: 3; the particle size of the alumina is 20 - 50 nm, and the average diameter of the carbon nanotubes is 10 nm;

[0049] Dissolve dopamine hydrochloride in Tris buffer solution, add the composite thermal conductive filler grafted with a silane coupling agent, form a uniform dispersion after ultrasonic treatment, add H2O2 to initiate oxidative polymerization, stir at a constant temperature of 30 °C for 3 h, after the reaction, centrifuge, wash with deionized water until neutral and then dry to obtain; the dosage ratio of the composite thermal conductive filler grafted with a silane coupling agent, dopamine hydrochloride, Tris buffer solution and H2O2 is 100 g: 1.5 g: 400 mL: 0.2 g, and the pH of the Tris buffer solution is 8.5;

[0050] The preparation method of this high thermal conductivity graphite calendered release film includes the steps of: ultrasonically mixing the formulated amount of dimethyl silicone oil, silicone resin, modified composite thermal conductive filler, defoaming agent, leveling agent, methyl ethyl ketone and hydrogen-containing silicone oil evenly, standing for defoaming to obtain a release agent; coating the release agent on the substrate layer by a microgravure coating method, with a coating speed of 30 m / min and a release layer thickness of 3.5 μm, and obtaining it after curing.

[0051] Comparative Example 1

[0052] Based on Example 1 with adjustments, different from Example 1 is that the polyimide film in the base material layer is not surface-coated, that is, the base material layer is a polyimide film.

[0053] Comparative Example 2

[0054] Based on Example 1 with adjustments, different from Example 1 is that during the preparation process of the modified composite thermal conductive filler, polydopamine is not used for coating.

[0055] Comparative Example 3

[0056] Based on Example 1 with adjustments, different from Example 1 is that during the preparation process of the modified composite thermal conductive filler, chemical grafting with silane coupling agent is not used.

[0057] Comparative Example 4

[0058] Based on Example 1 with adjustments, different from Example 1 is that the composite thermal conductive filler is not modified.

[0059] Comparative Example 5

[0060] Based on Example 1 with adjustments, different from Example 1 is that the composite thermal conductive filler does not contain hexagonal boron nitride.

[0061] Comparative Example 6

[0062] Based on Example 1 with adjustments, different from Example 1 is that the composite thermal conductive filler does not contain alumina.

[0063] Comparative Example 7

[0064] Based on Example 1 with adjustments, different from Example 1 is that the composite thermal conductive filler does not contain carbon nanotubes.

[0065] The high thermal conductivity graphite calendered release films prepared in Examples 1 - 4 and Comparative Examples 1 - 7 were tested:

[0066] 1. Thermal conductivity: The sample size is 10×10 mm, at a constant temperature of 25°C; measured using the hot disk method (TPS2200) according to the procedure specified in ISO 22007 - 2.

[0067] 2. Flexibility: Referring to the ASTM D2176 standard, using a bending tester, record the number of cycles of the film being bent 180° on a cylinder with a radius of 2 mm until cracks appear.

[0068] 4. Residual adhesion rate: Tested according to GB / T 25256 - 2010, with a peeling rate of 300 mm / min. The larger the residual adhesion rate, the higher the curing rate of the release film and the more complete the curing of the material.

[0069] 5. High-temperature stability: After being treated in an aging oven at 150°C for 500 hours, the thermal conductivity retention rate was detected.

[0070] The test results are shown in Table 1.

[0071] Table 1 Test Results

[0072]

[0073] Based on the above data, it can be seen that in Comparative Example 1, the uncoated polyimide substrate led to a significant decrease in thermal conductivity (0.14 W / m·K) and flexibility (>1000 times), indicating that the silicon carbide / graphene coating is crucial for improving thermal conductivity and mechanical properties. In Comparative Example 2, the absence of polydopamine coating caused a 32% decrease in thermal conductivity and an 8% decrease in the residual adhesion rate; in Comparative Example 3, the un-grafted silane coupling agent led to poor interfacial bonding, and the thermal conductivity retention rate dropped to 84.2%; in Comparative Example 4, the comprehensive performance of the unmodified filler was the worst, verifying the dual optimization effect of chemical grafting and polydopamine coating on the dispersibility and stability of the filler. In Comparative Example 5, the absence of two-dimensional boron nitride caused a 35% decrease in thermal conductivity because its flaky structure is the core for constructing in-plane heat conduction paths; in Comparative Example 6, the absence of alumina had a relatively small impact, but the spherical particles still contributed to filling the gaps to a certain extent; in Comparative Example 7, the absence of carbon nanotubes led to a reduction in one-dimensional heat conduction bridges and a significant decrease in flexibility, highlighting its reinforcing effect.

[0074] In addition, Example 1 achieved the best balance between thermal conductivity (0.31 W / m·K) and flexibility (>5000 times) through precise coating speed (25 m / min), gradient heating (5 - 9°C / min), and filler ratio, which also proved the importance of the synergy between material design and process control.

[0075] Finally, it should be noted that the above examples are only used to illustrate the present invention and do not limit the technical solutions described in the present invention; those of ordinary skill in the art should understand that the present invention can still be modified or equivalently replaced; and all technical solutions and their improvements that do not depart from the spirit and scope of the present invention should be covered by the scope of the claims of the present invention.

Claims

1. A high thermal conductivity graphite calendered release film, characterized in that, It includes a substrate layer and a release layer adhered to the surface of the substrate layer; the release layer is composed of the following materials in parts by weight: 30 - 35 parts of dimethyl silicone oil, 25 - 30 parts of silicone resin, 20 - 26 parts of modified composite thermal conductive filler, 0.5 - 1 part of defoaming agent, 0.2 - 0.5 part of leveling agent, 30 - 34 parts of methyl ethyl ketone, and 1 - 3 parts of hydrogen-containing silicone oil; wherein, the modified composite thermal conductive filler includes chemically grafting the composite thermal conductive filler with a silane coupling agent first, and then coating it with polydopamine.

2. The high thermal conductivity graphite calendered release film according to claim 1, characterized in that, The thickness of the substrate layer is 10 - 20μm, and the preparation steps include: mixing silicon carbide, graphene and ethanol, adding polyvinylpyrrolidone, ultrasonic dispersing and then centrifuging, and retaining the upper stable suspension; soaking the polyimide film in an alkaline solution for 5 - 10 minutes, washing and then drying; dropping the suspension onto the surface of the polyimide film, spin-coating at a low speed of 500 - 1000rpm for 10 - 12 seconds, then raising the speed to 2000 - 3000rpm for high-speed spin-coating for 30 - 35 seconds, controlling the film thickness to be 100 - 200nm, drying at 60 - 70°C for 1 - 2h, then heating to 120 - 140°C at a rate of 4 - 6°C / min, holding for 30 - 40min, and continuing to raise the temperature to 180 - 200°C at a rate of 8 - 10°C / min, and holding for 1 - 2 hours to obtain.

3. A highly thermally conductive graphite calendared release film according to claim 2, characterized in that The dosage ratio of the silicon carbide, graphene, ethanol and polyvinylpyrrolidone is (2 - 4)g : (0.5 - 1.5)g : (800 - 900)mL : (0.2 - 0.4)g.

4. A high thermal conductivity graphite calendered release film according to claim 1, characterized in that The composite thermal conductive filler includes hexagonal boron nitride, alumina and carbon nanotubes with a weight ratio of (15 - 20) : (8 - 12) : (3 - 5).

5. A highly thermally conductive graphite calendered release film according to claim 4, characterized in that, The particle size of the alumina is 20 - 50nm, and the average diameter of the carbon nanotubes is 9 - 11nm.

6. The high thermal conductivity graphite calendared release film according to claim 1, wherein, The preparation method of the modified composite thermal conductive filler includes: dissolving dopamine hydrochloride in Tris buffer solution, adding the composite thermal conductive filler grafted with a silane coupling agent, forming a uniform dispersion after ultrasonic treatment, adding H2O2 to initiate oxidative polymerization, stirring at a constant temperature of 25 - 30°C for 3 - 4h, centrifuging after the reaction, washing with deionized water until neutral and then drying to obtain.

7. A high thermal conductivity graphite calendered release film according to claim 6, characterized in that, The dosage ratio of the composite thermal conductive filler grafted with a silane coupling agent, dopamine hydrochloride, Tris buffer solution and H2O2 is 100g : (0.5 - 1.5)g : (400 - 500)mL : (0.1 - 0.2)g.

8. A highly thermally conductive graphite calendered release film according to claim 6, characterized in that, The preparation method of the composite thermal conductive filler grafted with a silane coupling agent includes: dispersing the composite thermal conductive filler in a mixed solution of ethanol and water, ultrasonic treating for 30min to form a uniform suspension, adding glacial acetic acid to adjust the pH to 4 - 5, and stirring for 10 - 15min; dropping KH - 550 into the suspension, stirring and reacting at a constant water bath temperature of 60 - 70°C for 3 - 4h, centrifuging and washing and drying after the reaction to obtain.

9. The high thermal conductivity graphite calendered release film according to claim 8, characterized in that, The weight ratio of the composite thermal conductive filler, ethanol, water and KH - 550 is 100 : (20 - 30) : (4 - 6) : (2 - 3).

10. A method for preparing a highly thermally conductive graphite calendared release film according to any one of claims 1-9, characterized in that the steps It includes: Mix the formula amount of dimethyl silicone oil, silicone resin, modified composite heat-conducting filler, defoamer, leveling agent, methyl ethyl ketone and hydrogen-containing silicone oil ultrasonically until evenly mixed, and let it stand for defoaming to obtain a release agent; Coat the release agent on the substrate layer by using a gravure coating method, with a coating speed of 20 - 30 m / min, and obtain the product after curing.

Images