Preparation method of phase change heat-conducting gasket and phase change heat-conducting gasket

Abstract

This invention discloses a method for preparing a phase change thermally conductive pad and the phase change thermally conductive pad itself. The preparation method includes: immersing multiple microporous graphite sheets in a phase change microcapsule suspension under vacuum to obtain multiple composite graphite sheets; coating the surface of each composite graphite sheet with liquid silicone rubber, and then winding them layer by layer along the surface direction of the composite graphite sheets under a preset tension to obtain a stacked graphite sheet composed of multiple composite graphite sheets; bonding two adjacent composite graphite sheets in the stacked graphite sheets along the thickness direction through a vulcanization molding process to obtain a graphite stack; and cutting the graphite stack along the thickness direction to obtain the phase change thermally conductive pad. The phase change thermally conductive pad prepared by this method has good thermal conductivity while also exhibiting good thermal and chemical stability under high-temperature operating conditions.

Description

Technical Field

[0001] This invention relates to the field of heat dissipation technology, and in particular to a method for preparing a phase change thermally conductive pad and a phase change thermally conductive pad prepared using this method. Background Technology

[0002] With the rapid development of electronic technology, electronic devices are becoming increasingly smaller and more integrated, leading to higher power density and a tendency for high heat generation that is difficult to dissipate in a timely manner. This significant heat causes core components to heat up rapidly, severely impacting the stable operation and long-term reliability of electronic products. Phase change materials (PCMs), due to their excellent porosity filling, phase change temperature control, corrosion resistance, and ease of processing, are increasingly being used in the thermal management of electronic devices. However, the application of traditional PCMs in thermal pads still presents the following problems:

[0003] 1. Traditional phase change materials have low thermal conductivity, and their use often relies on phase change materials, which makes it difficult to meet the requirements for high thermal conductivity.

[0004] 2. Molecular phase change materials are solid-liquid phase change materials, which are prone to leakage when used in high-temperature environments. Their thermal and chemical stability needs to be improved. They not only pollute electronic components and pose safety hazards, but also cannot meet the requirements for long-term use in harsh environments.

[0005] The present invention solves at least one of the above problems. Summary of the Invention

[0006] To address at least one of the problems in the background art, the present invention provides a method for preparing a phase change thermally conductive pad and a phase change thermally conductive pad prepared using the method. The phase change thermally conductive pad prepared by this method has good thermal conductivity while also exhibiting good thermal stability and chemical stability under high-temperature operating conditions.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A first aspect of the present invention provides a method for preparing a phase change thermal pad, comprising:

[0009] Multiple composite graphite sheets were obtained by immersing multiple microporous graphite sheets in a phase change microcapsule suspension under vacuum.

[0010] Liquid silicone rubber is coated onto the surface of each of the above composite graphite sheets, and then the sheets are rolled up layer by layer along the surface direction of the composite graphite sheets under a preset tension to obtain a stacked graphite sheet composed of multiple composite graphite sheets.

[0011] Along the thickness direction of the aforementioned stacked graphite sheets, two adjacent composite graphite sheets in the stacked graphite sheets are bonded together by a vulcanization molding process to obtain a graphite stack.

[0012] The graphite stack is cut along its thickness direction to obtain the phase change thermal pad.

[0013] Compared with existing technologies, the advantages of this invention are as follows: By immersing microporous graphite sheets in a phase change microcapsule suspension, the phase change microcapsules, acting as the phase change material, are fully filled into the micropores of the graphite sheets under the negative pressure of a vacuum environment, significantly improving the filling rate and uniformity of the phase change material in the graphite sheets; the use of a vulcanization molding process to cross-link the liquid silicone rubber on the surface of the composite graphite sheets, forming high-bond-energy chemical bonds, resulting in an "integrated" co-crosslinked structure between adjacent composite graphite sheets, far exceeding ordinary physical adhesion; and the use of a vertical orientation cutting process along the thickness direction to transform the lateral thermal conductivity of the graphite stack along the horizontal direction into the longitudinal thermal conductivity of the phase change thermal pad along the thickness direction, thereby constructing a high thermal conductivity pathway arranged along the thickness direction, significantly improving the thermal conductivity.

[0014] In some possible embodiments of the first aspect, the vulcanization temperature of the vulcanization molding is greater than the melting point of the phase change microcapsule core material and less than the decomposition temperature of the shell material of the phase change microcapsule; and / or, the phase change temperature of the phase change microcapsule is 30°C to 80°C.

[0015] In some possible embodiments of the first aspect, the above-mentioned cutting of the graphite stack along the thickness direction of the graphite stack to obtain the phase change thermal pad includes:

[0016] The graphite stack is cut along its thickness direction to obtain a gasket blank of a predetermined size.

[0017] An anti-oxidation layer is coated on the surface of the above-mentioned gasket blank to obtain the above-mentioned phase change thermal conductive gasket.

[0018] In some possible embodiments of the first aspect, the preparation method includes, prior to immersing a plurality of microporous graphite sheets in a phase change microcapsule suspension under vacuum, the preparation method comprising:

[0019] A surfactant was added to the above phase change microcapsule suspension.

[0020] In some possible embodiments of the first aspect, the above-mentioned method of immersing multiple microporous graphite sheets in a phase change microcapsule suspension under vacuum to obtain multiple composite graphite sheets includes:

[0021] Multiple graphite sheets with micropores are placed in a vacuum drying oven containing the above-mentioned phase change microcapsule suspension, so that the graphite sheets are immersed in the phase change microcapsule suspension.

[0022] Under the condition that the temperature inside the vacuum drying oven is 60℃~80℃, the vacuum drying oven is evacuated for 2h~3h to make the vacuum degree inside the vacuum drying oven reach the preset vacuum degree; wherein, the preset vacuum degree is 0.05Pa~0.1Pa;

[0023] Under the negative pressure of the preset vacuum degree, the graphite sheets are immersed in the phase change microcapsule suspension for 10 to 20 minutes, and then the temperature in the vacuum drying oven is cooled to room temperature to obtain multiple composite graphite sheets.

[0024] In some possible embodiments of the first aspect, the bonding of two adjacent composite graphite sheets in the stacked graphite sheets via a vulcanization molding process along the thickness direction of the stacked graphite sheets includes:

[0025] Under vacuum conditions of 0.2MPa to 0.3MPa and vulcanization temperature of 120℃ to 150℃, the liquid silicone rubber on the surface of the composite graphite sheet is subjected to a vulcanization crosslinking reaction for 30 min to 60 min, so that two adjacent composite graphite sheets along the thickness direction of the stacked graphite sheets are bonded together.

[0026] In some possible embodiments of the first aspect, the liquid silicone rubber is an organosilicon elastomer, the molecular structure of which has active hydroxyl groups, enabling it to form hydrogen bonds with the shell material of the phase change microcapsules.

[0027] In some possible embodiments of the first aspect, the shell material of the phase change microcapsule is polyamide resin, melamine resin or urea-formaldehyde resin, and the core material of the phase change microcapsule is paraffin wax.

[0028] In some possible embodiments of the first aspect, the coating thickness of the liquid silicone rubber is 20µm to 50µm.

[0029] In a second aspect, the present invention provides a phase change thermal pad prepared by the above-described preparation method. Attached Figure Description

[0030] Figure 1 This is a flowchart of the preparation method of the phase change thermal pad of the present invention;

[0031] Figure 2 This is a flowchart of step S1 of the present invention;

[0032] Figure 3 This is a flowchart of step S4 of the present invention. Detailed Implementation

[0033] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided to make the invention more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art.

[0034] The first aspect of the present invention, in conjunction with the appendix Figure 1 As shown, a method for preparing a phase change thermal pad is provided. As an embodiment of the preparation method, it includes the following steps S1-S4.

[0035] Step S1: Immerse multiple microporous graphite sheets in a phase change microcapsule suspension under vacuum.

[0036] In the process, multiple composite graphite sheets were obtained.

[0037] Optionally, the microporous graphite sheet can be an expanded graphite sheet or a graphite nano-sintered sheet, both of which are...

[0038] This involves introducing multiple micro- and nano-scale pores into a graphite sheet matrix. The number of graphite sheets can be two, three, or four, depending on the specific requirements.

[0039] Optionally, the porosity of the graphite sheets is 30%–40%, for example, it can be 30%, 35%, 40%, or higher.

[0040] The midpoint between any two.

[0041] Optionally, the shell material of the phase change microcapsule can be polyamide resin, melamine resin, or urea-formaldehyde resin, and the core material can be paraffin wax. The structural design of the phase change microcapsule effectively prevents leakage or overflow of the phase change material at high temperatures, improves the reliability and safety of using graphite sheets filled with phase change material, and overcomes the drawback of traditional molecular phase change materials being prone to contamination.

[0042] Optionally, the phase change temperature of the phase change microcapsules is 30℃ to 80℃, for example, it can be 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃ or any intermediate value between the two mentioned above; the mass fraction of the phase change microcapsules in the phase change microcapsule suspension is 50% to 80%, for example, it can be 50%, 55%, 60%, 65%, 70%, 75%, 80% or any intermediate value between the two mentioned above.

[0043] When microporous graphite sheets are immersed in a phase change microcapsule suspension, the phase change microcapsules, acting as the phase change material, are fully filled into the micropores of the graphite sheets under the negative pressure of a vacuum environment, significantly improving the filling rate and uniformity of the phase change material in the graphite sheets.

[0044] Preferably, before step S1 of immersing multiple graphite sheets with micropores in the phase change microcapsule suspension, the preparation method further includes adding a surfactant to the phase change microcapsule suspension.

[0045] For example, the surfactant can be coupling agent KH550, coupling agent KH560 or coupling agent KH570. The surfactant can improve the impregnation effect of the phase change microcapsule suspension on the graphite sheet and promote the interfacial bonding between the phase change microcapsule and the micropores of the graphite sheet.

[0046] Optionally, the surfactant in the phase change microcapsule suspension has a mass fraction of 0.5% to 1%, for example, it can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1% or any intermediate value between the two.

[0047] As a specific implementation of step S1, in conjunction with the appendix Figure 2 As shown, step S1 includes steps S11-S13.

[0048] Step S11: Place multiple graphite sheets with micropores in a vacuum drying oven containing a phase change microcapsule suspension, so that the graphite sheets are immersed in the phase change microcapsule suspension.

[0049] Step S12: Under the condition that the temperature inside the vacuum drying oven is 60℃~80℃, the vacuum drying oven is evacuated for 2h~3h to make the vacuum degree inside the vacuum drying oven reach the preset vacuum degree.

[0050] Optionally, the preset vacuum level is 0.05 Pa to 0.1 Pa, for example, it can be 0.05 Pa, 0.08 Pa, 0.1 Pa or any intermediate value between the two mentioned above.

[0051] For example, the temperature inside the vacuum drying oven can be 60°C, 65°C, 70°C, 75°C or any intermediate value of the above two; the vacuuming time can be 2h, 2.5h, 3h or any intermediate value of the above two.

[0052] Step S13: Under the negative pressure of a preset vacuum degree, the graphite sheets are immersed in the phase change microcapsule suspension for 10 min to 20 min, and then the temperature in the vacuum drying oven is cooled to room temperature to obtain multiple composite graphite sheets.

[0053] For example, the immersion time can be 10 min, 12 min, 14 min, 16 min, 18 min, 20 min or any intermediate value between the two mentioned above.

[0054] The phase change microcapsules, which are phase change materials, are fully impregnated with graphite sheets under a negative pressure of a preset vacuum of 0.05 Pa to 0.1 Pa, so that the phase change microcapsules are completely filled into the micropores of the graphite sheets, which further improves the filling rate and uniformity of the phase change material in the graphite sheets.

[0055] Step S2: Apply liquid silicone rubber to the surface of each composite graphite sheet, and roll it up layer by layer along the surface direction of the composite graphite sheet under a preset tension to obtain a stacked graphite sheet composed of multiple composite graphite sheets.

[0056] It should be noted that liquid silicone rubber is an organosilicon elastomer. The molecular structure of organosilicon elastomers has active hydroxyl groups, which can form hydrogen bonds with the shell material of phase change microcapsules.

[0057] Optionally, the coating thickness of the liquid silicone rubber is 20um to 50um, for example, it can be 20um, 25um, 30um, 35um, 40um, 45um, 50um or any intermediate value between the two mentioned above.

[0058] Optionally, the liquid silicone rubber is MQ silicone rubber, which is selected from SK thermally conductive silicone gel with model number CX-3180AB produced by Guangdong Chenxi New Material Technology Co., Ltd. or methyl MQ silicone resin with model number SK-MR-709S produced by Shenzhen Tianqi New Material Co., Ltd.

[0059] Optionally, the diameter of the winding machine's drum can be 200 mm; the preset tension of the winding machine is 0.5 MPa to 0.8 MPa, for example, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, or any intermediate value between the two. Under this preset tension condition, the winding machine can achieve layer-by-layer winding along the surface direction of the composite graphite sheet while effectively reducing interlayer bubbles.

[0060] Furthermore, interlayer air bubbles can be further eliminated through vacuum exhaust. The vacuum degree of vacuum exhaust can be -0.2MPa. This is the existing vacuum exhaust technology for winding machines, which will not be elaborated here.

[0061] Step S3: Along the thickness direction of the stacked graphite sheets, two adjacent composite graphite sheets in the stacked graphite sheets are bonded together by a vulcanization molding process to obtain a graphite stack.

[0062] Since the bonding strength and peel strength of adjacent composite graphite sheets in the stacked graphite sheets are not high when using ordinary physical bonding, a vulcanization molding process is used to vulcanize and crosslink the liquid silicone rubber on the surface of the composite graphite sheets, forming high bond energy chemical bonds (carbon-carbon bonds or carbon-sulfur bonds), so that the adjacent composite graphite sheets form an "integrated" co-crosslinked structure, which is far superior to ordinary physical bonding.

[0063] As a specific implementation of step S3, step S20 involves bonding two adjacent composite graphite sheets in the stacked graphite sheets along the thickness direction of the stacked graphite sheets using a vulcanization molding process.

[0064] Step S30: Under the conditions of vacuum degree of 0.2MPa~0.3MPa and vulcanization temperature of 120℃~150℃, the liquid silicone rubber on the surface of the composite graphite sheet is subjected to a vulcanization crosslinking reaction for 30min~60min, so as to bond two adjacent composite graphite sheets along the thickness direction of the stacked graphite sheets.

[0065] It should be noted that the vulcanization temperature for vulcanization molding is higher than the melting point of the phase change microcapsule core material but lower than the decomposition temperature of the phase change microcapsule shell material. This is because if the vulcanization temperature is too high, exceeding the decomposition temperature of the phase change microcapsule shell material, the phase change microcapsule wall material will thermally decompose, causing the phase change material to fail; if the vulcanization temperature is too low, less than or equal to the melting point of the phase change microcapsule core material, it will affect the actual production efficiency.

[0066] For example, the vacuum degree can be 0.2 Pa, 0.24 Pa, 0.28 Pa, 0.3 Pa, or any intermediate value of the two; the vulcanization temperature can be 120℃, 125℃, 130℃, 135℃, 140℃, 145℃, 150℃, or any intermediate value of the two; and the vulcanization crosslinking reaction time can be 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, or any intermediate value of the two.

[0067] Under these conditions, the chemical bonds (carbon-carbon bonds or carbon-sulfur bonds) formed by the sulfurization crosslinking reaction have high bond energies, and the co-crosslinking structure formed between adjacent composite graphite sheets has a good integration effect. The resulting graphite stack has good adhesion strength and peel strength.

[0068] Step S4: Cut the graphite stack along the thickness direction to obtain a phase change thermal pad.

[0069] Graphite stacks have a layered structure, exhibiting extremely high thermal conductivity in the horizontal direction (i.e., along the surface of the graphite stack), but poor thermal conductivity in the thickness direction (i.e., penetrating the surface of the graphite stack from top to bottom). This is because while heat travels quickly horizontally, it struggles to penetrate the gaps between layers. Therefore, this invention utilizes a vertically oriented cutting process along the thickness direction to transform the lateral thermal conductivity of the graphite stack into longitudinal thermal conductivity of the phase change thermal pad along the thickness direction. This creates highly conductive thermal pathways arranged along the thickness direction, significantly improving the thermal conductivity.

[0070] As a specific implementation of step S4, in conjunction with the appendix Figure 3 As shown, step S4 also includes steps S41 and S42.

[0071] Step S41: Cut the graphite stack along the thickness direction to obtain a gasket blank of a preset size.

[0072] Step S42: Coat the surface of the gasket blank with an anti-oxidation layer to obtain a phase change thermally conductive gasket.

[0073] The anti-oxidation layer can be an alumina coating or a ceramic coating, used to improve the corrosion resistance and service life of the phase change thermal pad.

[0074] In a second aspect, the present invention provides a phase change thermal pad prepared by the above-described preparation method.

[0075] The technical solution of this application will be described in more detail below. However, it should be understood that the following embodiments are merely for explaining and illustrating the technical solution, and do not limit the scope of this application. Moreover, unless otherwise specified, the various raw materials, reaction equipment, detection equipment, and methods used in the following embodiments are all known in the art.

[0076] Example 1

[0077] A method for preparing a phase change thermal pad includes the following steps S1-S6.

[0078] Step S1: Place two graphite sheets with micropores in a vacuum drying oven containing a phase change microcapsule suspension so that the graphite sheets are immersed in the phase change microcapsule suspension.

[0079] Among them, the graphite sheet with micropores is an expanded graphite sheet with a porosity of 30%, an average pore diameter of 30 μm, and a thickness of 0.1 mm; the phase change microcapsule suspension contains 50% phase change microcapsules by mass, and the phase change microcapsules are PCM-43 phase change microcapsules produced by Hangzhou Innok New Materials Co., Ltd.

[0080] Step S2: Under the condition that the temperature inside the vacuum drying oven is 60℃, the vacuum drying oven is evacuated for 2 hours so that the vacuum degree inside the vacuum drying oven reaches the preset vacuum degree of 0.05Pa.

[0081] Step S3: Under the negative pressure of a preset vacuum degree, the graphite sheets are immersed in the phase change microcapsule suspension for 10 minutes, and then the temperature in the vacuum drying oven is cooled to room temperature to obtain multiple composite graphite sheets.

[0082] Step S4: Coat the surface of each composite graphite sheet with a 20µm thick layer of liquid silicone rubber, and then use a winding machine to wind the composite graphite sheet layer by layer under a preset tension of 0.5MPa to obtain a stacked graphite sheet composed of two composite graphite sheets stacked together.

[0083] The liquid silicone rubber is MQ silicone rubber, which is selected from SK thermally conductive silicone gel with model number CX-3180AB produced by Guangdong Chenxi New Material Technology Co., Ltd.; the winding machine has a drum diameter of 200mm.

[0084] Step S5: Under the conditions of vacuum degree of 0.2MPa and vulcanization temperature of 120℃, the liquid silicone rubber on the surface of the composite graphite sheet is subjected to a vulcanization crosslinking reaction for 30 minutes, so that two adjacent composite graphite sheets along the thickness direction of the stacked graphite sheets are bonded together to obtain a graphite stack.

[0085] Step S6: Cut the graphite stack along the thickness direction to obtain a phase change thermal pad with a preset size of 200mm*200mm.

[0086] Example 2

[0087] A method for preparing a phase change thermal pad includes the following steps S1-S6.

[0088] Step S1: Place two graphite sheets with micropores in a vacuum drying oven containing a phase change microcapsule suspension so that the graphite sheets are immersed in the phase change microcapsule suspension.

[0089] Among them, the graphite sheet with micropores is an expanded graphite sheet with a porosity of 35%, an average pore size of 30 μm, and a thickness of 0.1 mm; the phase change microcapsule suspension contains 65% phase change microcapsules by mass, and the phase change microcapsules are PCM-43 phase change microcapsules produced by Hangzhou Innok New Materials Co., Ltd.

[0090] Step S2: Under the condition that the temperature inside the vacuum drying oven is 70℃, the vacuum drying oven is evacuated for 2.5 hours to make the vacuum degree inside the vacuum drying oven reach the preset vacuum degree of 0.08Pa.

[0091] Step S3: Under the negative pressure of a preset vacuum degree, the graphite sheets are immersed in the phase change microcapsule suspension for 10 minutes, and then the temperature in the vacuum drying oven is cooled to room temperature to obtain multiple composite graphite sheets.

[0092] Step S4: Coat the surface of each composite graphite sheet with a 35µm thick layer of liquid silicone rubber, and then use a winding machine to wind the composite graphite sheet layer by layer under a preset tension of 0.65MPa to obtain a stacked graphite sheet composed of two composite graphite sheets.

[0093] The liquid silicone rubber is MQ silicone rubber, which is selected from S-thermal conductive silicone gel with model number CX-3180AB produced by Guangdong Chenxi New Material Technology Co., Ltd.; the winding machine has a drum diameter of 200mm.

[0094] Step S5: Under the conditions of vacuum degree of 0.25MPa and vulcanization temperature of 135℃, the liquid silicone rubber on the surface of the composite graphite sheet is subjected to a vulcanization crosslinking reaction for 45 minutes, so that two adjacent composite graphite sheets along the thickness direction of the stacked graphite sheets are bonded together to obtain a graphite stack.

[0095] Step S6: Cut the graphite stack along the thickness direction to obtain a phase change thermal pad with a preset size of 200mm*200mm.

[0096] Example 3

[0097] A method for preparing a phase change thermal pad includes the following steps S1-S6.

[0098] Step S1: Place two graphite sheets with micropores in a vacuum drying oven containing a phase change microcapsule suspension so that the graphite sheets are immersed in the phase change microcapsule suspension.

[0099] Among them, the graphite sheet with micropores is an expanded graphite sheet with a porosity of 40%, an average pore diameter of 30 μm, and a thickness of 0.1 mm; the phase change microcapsule suspension contains 80% phase change microcapsules by mass, and the phase change microcapsules are PCM-43 phase change microcapsules produced by Hangzhou Innok New Materials Co., Ltd.

[0100] Step S2: Under the condition that the temperature inside the vacuum drying oven is 80℃, the vacuum drying oven is evacuated for 3 hours to make the vacuum degree inside the vacuum drying oven reach the preset vacuum degree of 0.1Pa.

[0101] Step S3: Under the negative pressure of a preset vacuum degree, the graphite sheets are immersed in the phase change microcapsule suspension for 20 minutes, and then the temperature in the vacuum drying oven is cooled to room temperature to obtain multiple composite graphite sheets.

[0102] Step S4: Coat the surface of each composite graphite sheet with a 50µm thick layer of liquid silicone rubber, and then use a winding machine to wind the composite graphite sheet layer by layer under a preset tension of 0.8MPa to obtain a stacked graphite sheet composed of two composite graphite sheets stacked together.

[0103] The liquid silicone rubber is MQ silicone rubber, which is selected from SK thermally conductive silicone gel with model number CX-3180AB produced by Guangdong Chenxi New Material Technology Co., Ltd.; the winding machine has a drum diameter of 200mm.

[0104] Step S5: Under the conditions of vacuum degree of 0.3MPa and vulcanization temperature of 150℃, the liquid silicone rubber on the surface of the composite graphite sheet is subjected to a vulcanization crosslinking reaction for 60 minutes, so that two adjacent composite graphite sheets along the thickness direction of the stacked graphite sheets are bonded together to obtain a graphite stack.

[0105] Step S6: Cut the graphite stack along the thickness direction to obtain a phase change thermal pad with a preset size of 200mm*200mm.

[0106] Example 4

[0107] A method for preparing a phase change thermal pad includes the following steps S1-S6.

[0108] Step S1: Place two graphite sheets with micropores in a vacuum drying oven containing a surfactant and a phase change microcapsule suspension, so that the graphite sheets are immersed in the phase change microcapsule suspension.

[0109] Among them, the graphite sheet with micropores is an expanded graphite sheet with a porosity of 35%, an average pore size of 30 μm, and a thickness of 0.1 mm; the phase change microcapsule suspension contains 65% phase change microcapsules by mass, and the phase change microcapsules are PCM-43 phase change microcapsules produced by Hangzhou Innok New Materials Co., Ltd.; the phase change microcapsule suspension contains 1% surfactant by mass, and the surfactant is KH550 coupling agent produced by Zhejiang Boiling Point Chemical Co., Ltd.

[0110] Step S2: Under the condition that the temperature inside the vacuum drying oven is 70℃, the vacuum drying oven is evacuated for 2.5 hours to make the vacuum degree inside the vacuum drying oven reach the preset vacuum degree of 0.08Pa.

[0111] Step S3: Under the negative pressure of a preset vacuum degree, the graphite sheets are immersed in the phase change microcapsule suspension for 10 minutes, and then the temperature in the vacuum drying oven is cooled to room temperature to obtain multiple composite graphite sheets.

[0112] Step S4: Coat the surface of each composite graphite sheet with a 35µm thick layer of liquid silicone rubber, and then use a winding machine to wind the composite graphite sheet layer by layer under a preset tension of 0.65MPa to obtain a stacked graphite sheet composed of two composite graphite sheets.

[0113] The liquid silicone rubber is MQ silicone rubber, which is selected from SK thermally conductive silicone gel with model number CX-3180AB produced by Guangdong Chenxi New Material Technology Co., Ltd.; the winding machine has a drum diameter of 200mm.

[0114] Step S5: Under the conditions of vacuum degree of 0.25MPa and vulcanization temperature of 135℃, the liquid silicone rubber on the surface of the composite graphite sheet is subjected to a vulcanization crosslinking reaction for 45 minutes, so that two adjacent composite graphite sheets along the thickness direction of the stacked graphite sheets are bonded together to obtain a graphite stack.

[0115] Step S6: Cut the graphite stack along the thickness direction to obtain a phase change thermal pad with a preset size of 200mm*200mm.

[0116] Example 5

[0117] The difference from Example 2 is that the liquid silicone rubber is methyl MQ silicone resin with model number SK-MR-709S produced by Shenzhen Tianqi New Materials Co., Ltd.

[0118] The phase change thermal pads of Examples 1-5 were subjected to the following performance tests;

[0119] 1. Thermal conductivity testing shall be conducted in accordance with ASTM D5470 standard;

[0120] 2. Phase change enthalpy is measured in accordance with ASTM D3418 standard;

[0121] 3.125℃ Aging Test: Tests the changes in thermal conductivity and phase change enthalpy.

[0122] The test results are shown in Table 1.

[0123] Table 1: Test Results of Examples 1-5

[0124]

[0125] As shown in Table 1, the thermal conductivity of the phase change thermal pads in Examples 1-5 is between 20 W / m·K and 30 W / m·K, and the phase change enthalpy is between 80 J / g and 120 J / g, indicating that the phase change thermal pads prepared by the present invention have good thermal conductivity. Under aging tests at a high temperature of 125℃, the changes in thermal conductivity and phase change enthalpy are both less than 10%, indicating that the phase change thermal pads prepared by the present invention also have good thermal stability and chemical stability.

[0126] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the invention without departing from the principles and spirit of the invention, and all such changes should fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a phase change thermally conductive pad, characterized in that, include: Multiple composite graphite sheets were obtained by immersing multiple microporous graphite sheets in a phase change microcapsule suspension under vacuum. Liquid silicone rubber is coated onto the surface of each composite graphite sheet, and then the sheets are rolled up layer by layer along the surface direction of the composite graphite sheet under a preset tension to obtain a stacked graphite sheet composed of multiple composite graphite sheets. Along the thickness direction of the stacked graphite sheets, two adjacent composite graphite sheets in the stacked graphite sheets are bonded together by a vulcanization molding process to obtain a graphite stack. The graphite stack is cut along its thickness direction to obtain the phase change thermal pad.

2. The preparation method according to claim 1, characterized in that, The vulcanization temperature of the vulcanization molding is greater than the melting point of the phase change microcapsule core material and less than the decomposition temperature of the shell material of the phase change microcapsule; and / or, the phase change temperature of the phase change microcapsule is 30℃~80℃.

3. The preparation method according to claim 1, characterized in that, The step of cutting the graphite stack along its thickness direction to obtain the phase change thermal pad includes: The graphite stack is cut along its thickness direction to obtain a gasket blank of a preset size; An anti-oxidation layer is coated on the surface of the gasket blank to obtain the phase change thermally conductive gasket.

4. The preparation method according to claim 1, characterized in that, The preparation method includes, prior to immersing multiple microporous graphite sheets in a phase change microcapsule suspension under vacuum, the following steps: A surfactant is added to the phase change microcapsule suspension.

5. The preparation method according to any one of claims 1-4, characterized in that, The process involves immersing multiple microporous graphite sheets in a phase change microcapsule suspension under vacuum to obtain multiple composite graphite sheets, including: Multiple graphite sheets with micropores are placed in a vacuum drying oven containing the phase change microcapsule suspension, so that the graphite sheets are immersed in the phase change microcapsule suspension. Under the condition that the temperature inside the vacuum drying oven is 60℃~80℃, the vacuum drying oven is evacuated for 2h~3h to make the vacuum degree inside the vacuum drying oven reach the preset vacuum degree; wherein, the preset vacuum degree is 0.05Pa~0.1Pa; Under the negative pressure of the preset vacuum degree, the graphite sheet is immersed in the phase change microcapsule suspension for 10 min to 20 min, and then the temperature in the vacuum drying oven is cooled to room temperature to obtain multiple composite graphite sheets.

6. The preparation method according to claim 1, characterized in that, The process of bonding two adjacent composite graphite sheets in the stacked graphite sheets along the thickness direction of the stacked graphite sheets using a vulcanization molding process includes: Under vacuum conditions of 0.2MPa to 0.3MPa and vulcanization temperature of 120℃ to 150℃, the liquid silicone rubber on the surface of the composite graphite sheet undergoes a vulcanization crosslinking reaction for 30 to 60 minutes to bond two adjacent composite graphite sheets along the thickness direction of the stacked graphite sheets.

7. The preparation method according to claim 1, characterized in that, The liquid silicone rubber is an organosilicon elastomer. The molecular structure of the organosilicon elastomer has active hydroxyl groups, which can form hydrogen bonds with the shell material of the phase change microcapsules.

8. The preparation method according to claim 1, characterized in that, The shell material of the phase change microcapsule is polyamide resin, melamine resin or urea-formaldehyde resin, and the core material of the phase change microcapsule is paraffin wax.

9. The preparation method according to claim 1, characterized in that, The coating thickness of the liquid silicone rubber is 20µm to 50µm.

10. A phase change thermal pad, characterized in that, It is prepared by any one of the preparation methods described in claims 1-9.

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