High-thermal-conductivity phase change sheet and preparation method therefor

Abstract

A high-thermal-conductivity phase change sheet and a preparation method therefor. The high-thermal-conductivity phase change sheet is prepared from the following raw materials in parts by mass: 3-5 parts of a resin, 80-100 parts of a thermally conductive filler, 0.1-1 part of a treating agent, 0.1-1 part of an antioxidant, and 1-2 parts of a phase change material, wherein the resin is low-molecular-weight polyisobutylene, the thermally conductive filler comprises aluminum powder of 10 μm, aluminum powder of 2 μm and zinc oxide of 0.2 μm, and heat treatment and vacuumizing operation are involved in the preparation process.

Description

A high thermal conductivity phase change sheet and its preparation method Technical Field

[0001] The present invention belongs to the field of thermal interface materials, in particular to the field of C08L83 / 00, and more specifically to a high thermal conductivity phase change sheet and a preparation method thereof. Background Art

[0002] With the advancement of science and technology and the advent of electronic information technology, smart devices and products are constantly emerging. Electronic technology products are becoming increasingly miniaturized, changing the way people live and work. The heat generated by electronic products during operation can damage the body, causing device aging, shortening lifespan, and malfunction. Therefore, how to quickly conduct and dissipate heat from the body is a critical technical problem that the electronics industry urgently needs to solve. Commonly used thermal conductive materials include thermal conductive silicone grease. Thermal conductive silicone grease has low thermal resistance, but it has a pump-out effect and is prone to contaminating equipment. Thermal conductive phase change materials are solid at room temperature and in a fluid paste at operating temperature. They can absorb heat and improve thermal conductivity. However, the thermal conductive phase change materials currently available on the market have poor aging resistance and are difficult to meet actual needs.

[0003] Prior art CN110615985A discloses a high thermal conductivity composite filler and its application. The raw materials for preparation mainly include polyamide resin, graphite, inorganic thermal conductive filler, wear-resistant ceramic powder, carbon fiber, diamond powder, glass fiber, flaky high thermal conductive carbon powder, etc. Graphite powder is first prepared, then mixed and stirred, and then added with resin for mixing, extrusion and granulation. The product has excellent wear resistance and thermal conductivity, but its aging resistance is poor; Prior art CN108753261A discloses a high K value phase change thermal conductive sheet and its preparation method. The thermal conductive filler is first baked, and then resin and phase change wax are added and heated, and then a cross-linking agent and catalyst are added and mixed and cooled. The specific heat capacity is large, and the thermal resistance is ≤0.45℃ / W, but there is still room for further reduction of the thermal resistance. Summary of the Invention

[0004] In order to solve the above technical problems, the first aspect of the present invention provides a high thermal conductivity phase change sheet, the raw materials for its preparation include 3-5 parts of resin, 80-100 parts of thermal conductive filler, 0.1-1 part of treatment agent, 0.1-1 part of antioxidant, and 1-2 parts of phase change material in parts by mass; the average molecular weight of the resin is less than 16,000, and the viscosity at 100°C is 10-1370cst.

[0005] Preferably, the resin includes one or more of silicone resin, hydroxyl-terminated polybutadiene, ethylene-vinyl acetate copolymer, polyisobutylene, epoxy resin, and polyamide resin.

[0006] More preferably, the resin is polyisobutylene.

[0007] More preferably, the average molecular weight of the polyisobutylene is 350-3500; as an implementable case, the molecular weight of the polyisobutylene may include one of 400, 680, 950, 1300, and 1400.

[0008] More preferably, the resin has an average molecular weight of 1400 and a viscosity of 810 cst at 100° C., and can be purchased from Daelim of Korea.

[0009] Preferably, the thermally conductive filler includes at least one of aluminum oxide, zinc oxide, boron nitride, aluminum nitride, aluminum powder, silver powder, graphene, and carbon nanotubes.

[0010] Further preferably, the thermally conductive filler includes aluminum powder and zinc oxide.

[0011] Preferably, the particle size of the aluminum powder is 0.1-20 μm.

[0012] Further preferably, the particle size of the aluminum powder is 1-10 μm; as an implementable case, the particle size of the aluminum powder includes one or more of 1 μm, 2 μm, 3 μm, 5 μm, and 10 μm.

[0013] More preferably, the aluminum powder has a particle size of 2 μm and 10 μm.

[0014] Preferably, the particle size of the zinc oxide is 0.1-2 μm.

[0015] More preferably, the particle size of the zinc oxide is 0.2 μm.

[0016] Preferably, the mass ratio of 10 μm aluminum powder, 2 μm aluminum powder and 0.2 μm zinc oxide is (40-50): (20-30): (20-25).

[0017] Further preferably, the mass ratio of the 10 μm aluminum powder, 2 μm aluminum powder and 0.2 μm zinc oxide is (45-46): (23-25): (22-25).

[0018] Preferably, the treating agent comprises one of a silane coupling agent, a titanate coupling agent and an aluminate coupling agent.

[0019] More preferably, the treatment agent is a titanate coupling agent.

[0020] Further preferably, the phthalate titanate coupling agent includes: diisopropoxy diacetylacetonate, isopropyl tristearate titanate, isopropyl dioleyl (dioctyl phosphate) titanate, isopropyl trioleyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, bis (dioctyl pyrophosphate) ethylene titanate, which can be purchased from Nanjing Aocheng Chemical.

[0021] Preferably, the antioxidants are hindered phenol antioxidants and phosphite antioxidants.

[0022] Further preferably, the hindered phenol antioxidant includes one of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl]pentaerythritol ester, 2,6-di-tert-butyl-4-methylphenol, and β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

[0023] More preferably, the hindered phenol antioxidant includes tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl]pentaerythritol ester, also known as antioxidant 1010.

[0024] Further preferably, the phosphite antioxidant includes one of benzyl diisopropylate (2-methylpropylene glycol), tris (2,4-di-tert-butyl-6-methylphenoxycarbonyl) acetate, eicosyl di(β-naphthol) phosphate, and di-tert-butylphenol phosphate.

[0025] More preferably, the phosphite antioxidant includes tris(2,4-di-tert-butyl-6-methylphenoxycarbonyl)acetate, also known as antioxidant 168.

[0026] Preferably, the mass ratio of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl]pentaerythritol ester and tris(2,4-di-tert-butyl-6-methylphenoxycarbonyl)acetate is (2-5):1.

[0027] Preferably, the phase change material includes one or more of paraffin wax, silicone wax, beeswax, and microcrystalline wax.

[0028] A second aspect of the present invention provides a method for preparing a high thermal conductivity phase change sheet, comprising at least the following steps:

[0029] S1. Add resin and phase change material into a planetary mixer and stir evenly at 60-80℃;

[0030] S2. Add thermal conductive filler, treatment agent, and antioxidant in sequence, mix well, and stir at 60-75°C for 1-3 hours;

[0031] S3, heating to 90-108°C, vacuuming for 1-2 hours;

[0032] S4. Discharge the material and use a calender to press it into different thicknesses. Beneficial effects

[0033] (1) The low molecular weight polyisobutylene with an average molecular weight of 1400 in the present invention, as the main raw material for preparing the high thermal conductivity phase change sheet, has the characteristics of high softness and conformability, which makes the high thermal conductivity phase change sheet have suitable viscosity and can load thermal conductive fillers and phase change materials, providing more attachment sites for compound thermal conductive fillers of different particle sizes, thereby improving the dispersion uniformity and stability of the preparation system. Under the action of the phase change material, the possibility of agglomeration between thermal conductive fillers can also be reduced. In addition, the low molecular weight polyisobutylene can provide maximum wetting to achieve effective heat transfer, thereby significantly reducing the interfacial thermal resistance, allowing a continuous thermal conductive phase to be formed between the thermal conductive fillers, providing a thermal path for heat dissipation, increasing the thermal conductivity of the high thermal conductivity phase change sheet, and reducing the thermal resistance of the material. At the same time, the inventors have found that the best implementation method is to use polyisobutylene with an average molecular weight of 1400 and a viscosity of 810 cSt at 100°C. If a polyisobutylene with a large molecular weight is selected, it is difficult to fill more thermally conductive powder, which is not conducive to the high thermal conductivity and low thermal resistance of the thermally conductive phase change sheet. In addition, the thermal conductive material in the present invention includes small-particle fillers of 2μm aluminum powder and 0.2μm zinc oxide. If the viscosity of the polyisobutylene is too high, it is not conducive to the uniform dispersion of the small-particle filler, which is not conducive to the low thermal resistance and high thermal conductivity performance of the high thermal conductivity phase change sheet.

[0034] (2) In the present invention, in order to improve the thermal conductivity of the high thermal conductivity phase change sheet and reduce the thermal resistance, the inventors preferably use aluminum powder as the main thermal conductive filler. In order to improve the dispersion uniformity of the thermal conductive material, the present invention selects a compound of aluminum powder with a particle size of 2μm and 10μm. The compound of aluminum powder with large and small particle sizes can improve the uniformity of the filler, but it will cause the density of the thermal conductive filler in polyisobutylene with an average molecular weight of 1400 to be relatively low, and a small amount of bubbles may exist in the phase change sheet, which is not conducive to improving the thermal conductivity of the material. After a large number of experiments, the inventors found that when zinc oxide with a smaller particle size of 0.2μm is added to the thermal conductive filler, it can be better filled in the preparation system, effectively improving the dispersion uniformity of the thermal conductive filler in the polyisobutylene system, avoiding the generation of tiny bubbles, thereby effectively improving the thermal conductivity and reducing the thermal resistance.

[0035] (3) The thermally conductive phase change sheets currently on the market have the defect of poor aging resistance. In order to solve this technical problem, the present invention adds antioxidant 1010 and antioxidant 168 to the raw materials for compounding, which can improve the aging resistance of the product to a certain extent. At the same time, the inventors found that the use of heat treatment technology and vacuum steps in the preparation process can extract small molecules and moisture from the system, further improving the aging resistance of the phase change sheet.

[0036] (IV) The raw materials for preparing the high thermal conductivity phase change sheet provided by the present invention are simple and easy to obtain, the preparation process cost is low, and the thermal conductivity of the obtained finished product is not less than 5.5W / m*K and the thermal resistance is less than 0.1℃*cm 2 / W, adopts a variety of thermal conductive fillers mixed and matched, with special treatment agents to achieve high filling of powder, the product has excellent actual performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG1 is a schematic diagram of the 1000h aging treatment of the product obtained in Example 1.

[0038] FIG2 is a schematic diagram of a high and low temperature cycle test of -40 to 85° C. for the product obtained in Example 1.

[0039] FIG3 is a schematic diagram of a double 85 test of the product obtained in Example 1. DETAILED DESCRIPTION

[0040] Example 1

[0041] In the first aspect of this embodiment, a high thermal conductivity phase change sheet is provided, the raw materials for its preparation are calculated by weight: 4.6 parts of polyisobutylene (average molecular weight of 1400, viscosity of 810 cst at 100°C, purchased from Daelim, South Korea), 45 parts of 10 μm particle size aluminum powder, 23 parts of 2 μm particle size aluminum powder, 25 parts of 0.2 μm particle size zinc oxide, 0.5 parts of diisopropoxy diacetylacetonate titanate (purchased from Nanjing Aocheng), 0.3 parts of antioxidant 1010 (purchased from BASF), 0.1 parts of antioxidant 168 (purchased from BASF), and 1.5 parts of 70# microcrystalline wax (purchased from Sinopec Maoming).

[0042] A second aspect of this embodiment provides a method for preparing a high thermal conductivity phase change sheet, which specifically comprises the following steps:

[0043] S1. Add resin and phase change material into a planetary mixer and mix them evenly at 65°C.

[0044] S2. Add thermal conductive filler, treatment agent, and antioxidant in sequence, mix well, and stir at 65°C for 1 hour;

[0045] S3, heating to 100℃ and vacuuming for 1h;

[0046] S4. Discharge the material and use a calender to press it into different thicknesses.

[0047] FIG1 is a schematic diagram of the aging resistance 1000h treatment of the product obtained in this embodiment, and the test standard is GB / T2423.50-2012.

[0048] FIG2 is a schematic diagram of a high and low temperature cycle test of the product obtained in this embodiment at -40 to 85° C., according to the test standard GB / T2423.50-2012.

[0049] FIG3 is a schematic diagram of a double 85 test of the product obtained in this embodiment, the test standard being GB / T2423.50-2012.

[0050] Example 2

[0051] In the first aspect of this embodiment, a high thermal conductivity phase change sheet is provided, the raw materials for its preparation are, in parts by mass, 4.6 parts of polyisobutylene (average molecular weight of 1400, viscosity of 810 cst at 100°C, purchased from Daelim, South Korea), 45 parts of 10 μm particle size aluminum powder, 26 parts of 2 μm particle size aluminum powder, 22 parts of 0.2 μm particle size zinc oxide, 0.5 parts of diisopropoxy diacetylacetonate titanate (purchased from Nanjing Aocheng), 0.3 parts of antioxidant 1010 (purchased from BASF), 0.1 parts of antioxidant 168 (purchased from BASF), and 1.5 parts of 70# microcrystalline wax (purchased from Sinopec Maoming).

[0052] A second aspect of this embodiment provides a method for preparing a high thermal conductivity phase change sheet, which specifically comprises the following steps:

[0053] S1. Add resin and phase change material into a planetary mixer and mix them evenly at 65°C.

[0054] S2. Add thermal conductive filler, treatment agent, and antioxidant in sequence, mix well, and stir at 65°C for 1 hour;

[0055] S3, heating to 100℃ and vacuuming for 1h;

[0056] S4. Discharge the material and use a calender to press it into different thicknesses.

[0057] Example 3

[0058] The first aspect of this embodiment provides a high thermal conductivity phase change sheet, the raw materials for its preparation are, in parts by mass, 3.9 parts of polyisobutylene (average molecular weight of 1400, viscosity of 810 cst at 100°C, purchased from Daelim, South Korea), 46 parts of 10 μm particle size aluminum powder, 23 parts of 2 μm particle size aluminum powder, 25 parts of 0.2 μm particle size zinc oxide, 0.5 parts of isopropyl dioleyl (dioctyl phosphate) titanate (purchased from Nanjing Aocheng), 0.3 parts of antioxidant 1010 (purchased from BASF), 0.1 parts of antioxidant 168 (purchased from BASF), and 1.2 parts of 70# microcrystalline wax (purchased from Sinopec Maoming).

[0059] A second aspect of this embodiment provides a method for preparing a high thermal conductivity phase change sheet, which specifically comprises the following steps:

[0060] S1. Add resin and phase change material into a planetary mixer and mix them evenly at 65°C.

[0061] S2. Add thermal conductive filler, treatment agent, and antioxidant in sequence, mix well, and stir at 65°C for 1 hour;

[0062] S3, heating to 100℃ and vacuuming for 1h;

[0063] S4. Discharge the material and use a calender to press it into different thicknesses.

[0064] Example 4

[0065] In the first aspect of this embodiment, a high thermal conductivity phase change sheet is provided, the raw materials for its preparation are, in parts by mass, 4.6 parts of polyisobutylene (average molecular weight of 1400, viscosity of 810 cst at 100°C, purchased from Daelim, South Korea), 45 parts of 10 μm particle size aluminum powder, 23 parts of 2 μm particle size aluminum powder, 25 parts of 0.2 μm particle size zinc oxide, 0.5 parts of bis(dioctyloxypyrophosphate)ethylene titanate (purchased from Nanjing Aocheng), 0.2 parts of antioxidant 1010 (purchased from BASF), 0.2 parts of antioxidant 168 (purchased from BASF), and 1.5 parts of 70# microcrystalline wax (purchased from Sinopec Maoming).

[0066] A second aspect of this embodiment provides a method for preparing a high thermal conductivity phase change sheet, which specifically comprises the following steps:

[0067] S1. Add resin and phase change material into a planetary mixer and mix them evenly at 65°C.

[0068] S2. Add thermal conductive filler, treatment agent, and antioxidant in sequence, mix well, and stir at 65°C for 1 hour;

[0069] S3, heating to 100℃ and vacuuming for 1h;

[0070] S4. Discharge the material and use a calender to press it into different thicknesses.

[0071] Comparative Example 1

[0072] The first aspect of this comparative example provides a high thermal conductivity phase change sheet, the raw materials for its preparation are, in parts by mass, 5.6 parts of polyisobutylene (average molecular weight of 1400, viscosity of 810 cst at 100°C, purchased from Daelim, South Korea), 45 parts of 10 μm particle size aluminum powder, 23 parts of 2 μm particle size aluminum powder, 24 parts of 0.2 μm particle size zinc oxide, 0.5 parts of diisopropoxy diacetylacetonate titanate (purchased from Nanjing Aocheng), 0.3 parts of antioxidant 1010 (purchased from BASF), 0.1 parts of antioxidant 168 (purchased from BASF), and 1.5 parts of 70# microcrystalline wax (purchased from Sinopec Maoming).

[0073] The second aspect of this comparative example provides a method for preparing a high thermal conductivity phase change sheet, which specifically comprises the following steps:

[0074] S1. Add resin and phase change material into a planetary mixer and mix them evenly at 65°C.

[0075] S2. Add thermal conductive filler, treatment agent, and antioxidant in sequence, mix well, and stir at 65°C for 1 hour;

[0076] S3, heating to 100℃ and vacuuming for 1h;

[0077] S4. Discharge the material and use a calender to press it into different thicknesses.

[0078] Comparative Example 2

[0079] The first aspect of this comparative example provides a high thermal conductivity phase change sheet, the raw materials for its preparation are, in parts by mass, 6.6 parts of polyisobutylene (average molecular weight of 1400, viscosity of 810 cst at 100°C, purchased from Daelim, South Korea), 45 parts of 10 μm particle size aluminum powder, 23 parts of 2 μm particle size aluminum powder, 23 parts of 0.2 μm particle size zinc oxide, 0.5 parts of diisopropoxy diacetylacetonate titanate (purchased from Nanjing Aocheng), 0.3 parts of antioxidant 1010 (purchased from BASF), 0.1 parts of antioxidant 168 (purchased from BASF), and 1.5 parts of 70# microcrystalline wax (purchased from Sinopec Maoming).

[0080] The second aspect of this comparative example provides a method for preparing a high thermal conductivity phase change sheet, which specifically comprises the following steps:

[0081] S1. Add resin and phase change material into a planetary mixer and mix them evenly at 65°C.

[0082] S2. Add thermal conductive filler, treatment agent, and antioxidant in sequence, mix well, and stir at 65°C for 1 hour;

[0083] S3, heating to 100℃ and vacuuming for 1h;

[0084] S4. Discharge the material and use a calender to press it into different thicknesses.

[0085] Comparative Example 3

[0086] The first aspect of this comparative example provides a high thermal conductivity phase change sheet, the raw materials for its preparation are, in parts by mass, 4.6 parts of polyisobutylene (average molecular weight of 1400, viscosity of 810 cst at 100°C, purchased from Daelim, South Korea), 45 parts of 10 μm particle size aluminum powder, 23 parts of 2 μm particle size aluminum powder, 24 parts of 0.2 μm particle size zinc oxide, 0.5 parts of diisopropoxy diacetylacetonate titanate (purchased from Nanjing Aocheng), 0.3 parts of antioxidant 1010 (purchased from BASF), 0.1 parts of antioxidant 168 (purchased from BASF), and 2.5 parts of 70# microcrystalline wax (purchased from Sinopec Maoming).

[0087] The second aspect of this comparative example provides a method for preparing a high thermal conductivity phase change sheet, which specifically comprises the following steps:

[0088] S1. Add resin and phase change material into a planetary mixer and mix them evenly at 65°C.

[0089] S2. Add thermal conductive filler, treatment agent, and antioxidant in sequence, mix well, and stir at 65°C for 1 hour;

[0090] S3, heating to 100℃ and vacuuming for 1h;

[0091] S4. Discharge the material and use a calender to press it into different thicknesses.

[0092] Comparative Example 4

[0093] The first aspect of this comparative example provides a high thermal conductivity phase change sheet, the raw materials for its preparation are, in parts by mass, 5.6 parts of polyisobutylene (average molecular weight of 1400, viscosity of 810 cst at 100°C, purchased from Daelim, South Korea), 45 parts of 10 μm particle size aluminum powder, 23 parts of 2 μm particle size aluminum powder, 23 parts of 0.2 μm particle size zinc oxide, 0.5 parts of diisopropoxy diacetylacetonate titanate (purchased from Nanjing Aocheng), 0.3 parts of antioxidant 1010 (purchased from BASF), 0.1 parts of antioxidant 168 (purchased from BASF), and 5.5 parts of 70# microcrystalline wax (purchased from Sinopec Maoming).

[0094] The second aspect of this comparative example provides a method for preparing a high thermal conductivity phase change sheet, which specifically comprises the following steps:

[0095] S1. Add resin and phase change material into a planetary mixer and mix them evenly at 65°C.

[0096] S2. Add thermal conductive filler, treatment agent, and antioxidant in sequence, mix well, and stir at 65°C for 1 hour;

[0097] S3, heating to 100℃ and vacuuming for 1h;

[0098] S4. Discharge the material and use a calender to press it into different thicknesses.

[0099] Performance evaluation

[0100] Test objects and test results are detailed in Table 1 and Table 2

[0101] Table 1

[0102] Table 2

Claims

1. A high thermal conductivity phase change sheet, characterized by: The raw materials for preparation include 3-5 parts of resin, 80-100 parts of thermal conductive filler, 0.1-1 part of treatment agent, 0.1-1 part of antioxidant and 1-2 parts of phase change material in terms of mass. The average molecular weight of the resin is less than 16,000 and the viscosity at 100° C. is 10-1370 cst.

2. The high thermal conductivity phase change sheet according to claim 1, wherein: The resin includes one or more of organic silicone resin, hydroxyl-terminated polybutadiene, ethylene-vinyl acetate copolymer, polyisobutylene, epoxy resin, and polyamide resin.

3. The high thermal conductivity phase change sheet according to claim 2, wherein: The resin is polyisobutylene.

4. The high thermal conductivity phase change sheet according to claim 3, wherein: The average molecular weight of the polyisobutylene is 350-3500.

5. The high thermal conductivity phase change sheet according to claim 1, wherein: The thermal conductive filler includes at least one of aluminum oxide, zinc oxide, boron nitride, aluminum nitride, aluminum powder, silver powder, graphene, and carbon nanotubes.

6. The high thermal conductivity phase change sheet according to claim 5, wherein: The thermal conductive filler comprises aluminum powder and zinc oxide.

7. The high thermal conductivity phase change sheet according to claim 6, wherein: The particle size of the aluminum powder is 0.1-20 μm.

8. The high thermal conductivity phase change sheet according to claim 7, wherein: The aluminum powder has a particle size of 2 μm and 10 μm.

9. The high thermal conductivity phase change sheet according to claim 6, wherein: The particle size of the zinc oxide is 0.1-2 μm.

10. A method for preparing a high thermal conductivity phase change sheet according to any one of claims 1 to 9, characterized in that: At least the following steps are included: S1. Add resin and phase change material into a planetary mixer and stir evenly at 60-80℃; S2. Add thermal conductive filler, treatment agent, and antioxidant in sequence, mix well, and stir at 60-75°C for 1-3 hours; S3, heating to 90-108°C, vacuuming for 1-2 hours; S4. Discharge the material and use a calender to press it into different thicknesses.

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