Low-thermal-resistance low-pumping-out heat conduction phase change material and preparation method thereof

Abstract

The invention belongs to the technical field of heat-conducting phase-change materials, and relates to a low-heat-resistance low-pumping-out heat-conducting phase-change material and a preparation method thereof.The heat-conducting phase-change material is prepared from, by weight, 2-15 parts of base resin, 1-3 parts of modified phase-change wax, 90-95 parts of filler, 0.5-2 parts of coupling agent and 0.1-0.5 part of antioxidant; the base resin is polyolefin with the end capped by double hydroxyl groups; the modified phase change wax is phase change wax grafted with maleic anhydride groups. According to the heat-conducting phase-change material disclosed by the invention, hydroxyl-terminated polyolefin rubber is used as basic resin, modified paraffin grafted with a maleic anhydride group is used as phase-change wax, and the maleic anhydride group grafted with the phase-change wax can chemically react with hydroxyl of the basic resin, so that a cross-linked network is constructed in a system, and temperature cycle pumping is reduced; meanwhile, the crosslinking degree of the system can be controlled by reasonably matching the ratio of the basic resin to the modified phase change wax, so that low thermal resistance is kept.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal conductive phase change materials, and in particular relates to a low thermal resistance and low pump-out thermal conductive phase change material and a preparation method thereof. Background Art

[0002] Thermally conductive phase change materials have the characteristics of thermally conductive gaskets and thermally conductive silicone grease: they are solid at room temperature and can be mounted on the surface of electronic components like thermally conductive gaskets; after being heated, they have a certain fluidity like thermally conductive silicone grease. Thermally conductive phase change materials generally achieve "phase change" after being heated by adding phase change wax. When the ambient temperature exceeds its phase change point, the phase change wax changes from solid to liquid, thereby reducing the viscosity of the entire system, allowing the thermally conductive phase change material to achieve low bond layer thickness (BLT) and low thermal resistance under pressure. However, the high fluidity of the phase change wax after being heated also makes it easy to pump out during the temperature cycle, resulting in the loss of local thermally conductive phase change material and the generation of hot spots. Summary of the invention

[0003] In view of the deficiencies of the above-mentioned prior art, the present invention provides a low thermal resistance and low pump-out thermal conductive phase change material and a preparation method thereof. The specific technical scheme is as follows:

[0004] The first object of the present invention is to provide a low thermal resistance and low pump-out thermal conductive phase change material, comprising the following components in parts by weight:

[0005] 2-15 parts of base resin, 1-3 parts of modified phase change wax, 90-95 parts of filler, 0.5-2 parts of coupling agent, 0.1-0.5 parts of antioxidant;

[0006] The base resin is a dihydroxy-terminated polyolefin; the modified phase-change wax is a phase-change wax grafted with maleic anhydride groups.

[0007] Furthermore, the mass ratio of the base resin to the modified phase change wax is 2-5:1.

[0008] In the composition of the low thermal resistance and low pump-out thermal conductive phase change material of the present invention, the mass ratio of the base resin to the modified phase change wax is 2-5:1. If the ratio is greater than 5:1, the content of the phase change wax is too low and the viscosity of the system cannot be effectively reduced to achieve low thermal resistance; if the ratio is lower than 2:1, the cross-linking degree of the system is too high and the thermal fluidity is insufficient to achieve low thermal resistance.

[0009] Furthermore, the dihydroxy-terminated polyolefin is one or a mixture of dihydroxy-terminated polyisobutylene, dihydroxy-terminated polybutadiene, dihydroxy-terminated polybutylene, and dihydroxy-terminated ethylene-propylene rubber, and has a molecular weight of 1000-2000.

[0010] Furthermore, the preparation method of the modified phase change wax is as follows: the phase change wax is dissolved in xylene, and then maleic anhydride is added to carry out graft polymerization under the action of an initiator to obtain the modified phase change wax.

[0011] Furthermore, the phase-changing wax is solid paraffin with a melting point of 40°C-70°C.

[0012] Furthermore, the filler is a ceramic filler and / or a metal filler; the ceramic filler is one or more of aluminum oxide, aluminum nitride, silicon nitride, and zinc oxide; the metal filler is one or more of silver powder, aluminum powder, and copper powder.

[0013] Furthermore, the coupling agent is one or more of a silane coupling agent, a titanate coupling agent, a phosphate coupling agent, and a borate coupling agent.

[0014] Furthermore, the antioxidant is one or more of BASF 1010, 1076, and 1098.

[0015] The second object of the present invention is to provide a method for preparing the above-mentioned low thermal resistance and low pump-out thermal conductive phase change material, comprising the following steps:

[0016] The base resin, modified phase change wax and antioxidant are vacuum stirred at 100-120°C until they are uniform, then the coupling agent is added and vacuum stirred until they are uniform, and finally the filler is added and vacuum stirred until they are uniform, thereby obtaining a low thermal resistance and low pump-out thermal conductive phase change material.

[0017] The beneficial effects of the present invention are:

[0018] The thermally conductive phase change material prepared by the present invention uses hydroxyl-terminated polyolefin rubber as a base resin and modified paraffin grafted with maleic anhydride groups as a phase change wax. The maleic anhydride groups grafted with the phase change wax can chemically react with the hydroxyl groups of the base resin, thereby constructing a cross-linked network in the system to reduce temperature cycle pumping. At the same time, a reasonable ratio between the base resin and the modified phase change wax can control the degree of cross-linking of the system, thereby maintaining low thermal resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a picture of the thermal conductive phase change material prepared in Example 1 of the present invention after 1000 temperature cycles;

[0020] Figure 2 This is a picture of the thermally conductive phase change material prepared using unmodified phase change wax in Comparative Example 1 of the present invention after 1000 cycles of temperature cycling. DETAILED DESCRIPTION

[0021] The principles and features of the present invention are described below in conjunction with embodiments. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0022] Preparation of modified phase change wax:

[0023] By weight, 100 parts of solid paraffin are heated and dissolved in 150 parts of xylene at 120°C, and then 5 parts of maleic anhydride are added to carry out graft polymerization reaction for 2 hours under the action of 0.5 parts of initiator di-tert-butyl peroxide to prepare a modified phase change wax. The solid paraffin is No. 50 solid paraffin produced by China National Petroleum Corporation, and the phase change temperature of the prepared modified phase change wax is 50°C.

[0024] Example 1

[0025] Preparation of a low thermal resistance and low pump-out thermal conductive phase change material:

[0026] In parts by weight, 6 parts of dihydroxy-terminated polyisobutylene rubber with a molecular weight of 1500, 2 parts of modified phase change wax and 0.1 parts of antioxidant BASF 1076 are vacuum stirred at 110°C until they are uniform, 1 part of hexadecyltrimethoxysilane coupling agent is added and vacuum stirred until they are uniform, and finally 90.9 parts of filler (aluminum oxide with a particle size of 3 μm and zinc oxide with a mass ratio of 3:1 with a particle size of 0.5 μm) are added and vacuum stirred until they are uniform, thus obtaining a low thermal resistance and low pump-out thermal conductive phase change material.

[0027] Example 2

[0028] Preparation of a low thermal resistance and low pump-out thermal conductive phase change material:

[0029] By weight, 5 parts of dihydroxy-terminated polyisobutylene rubber with a molecular weight of 1500, 1.7 parts of modified phase change wax and 0.1 parts of antioxidant BASF 1076 are vacuum stirred at 110°C until they are uniform, and then 0.8 parts of hexadecyltrimethoxysilane coupling agent are added and vacuum stirred until they are uniform, and finally 92.4 parts of filler (aluminum oxide with a particle size of 3 μm and zinc oxide with a mass ratio of 3:1 with a particle size of 0.5 μm) are added and vacuum stirred until they are uniform, so as to obtain a low thermal resistance and low pump-out thermal conductive phase change material.

[0030] Comparative Example 1

[0031] Preparation of a thermally conductive phase change material:

[0032] In parts by weight, 6 parts of dihydroxy-terminated polyisobutylene rubber with a molecular weight of 1500, 2 parts of solid paraffin (No. 50 solid paraffin of China National Petroleum Corporation) and 0.1 parts of antioxidant BASF 1076 are vacuum stirred at 110°C until they are uniform, and then 1 part of hexadecyltrimethoxysilane coupling agent is added and vacuum stirred until they are uniform, and finally 90.9 parts of filler (aluminum oxide with a particle size of 3 μm and zinc oxide with a mass ratio of 3:1) are added and vacuum stirred until they are uniform, to obtain a thermal conductive phase change material.

[0033] Comparative Example 2

[0034] Preparation of a thermally conductive phase change material:

[0035] In parts by weight, 5 parts of dihydroxy-terminated polyisobutylene rubber with a molecular weight of 1500, 3 parts of modified phase change wax and 0.1 parts of antioxidant BASF 1076 are vacuum stirred at 110°C until they are uniform, then 1 part of hexadecyltrimethoxysilane coupling agent is added and vacuum stirred until they are uniform, and finally 90.9 parts of filler (aluminum oxide with a particle size of 3 μm and zinc oxide with a mass ratio of 3:1 with a particle size of 0.5 μm) are added and vacuum stirred until they are uniform, thus obtaining a low thermal resistance and low pump-out thermal conductive phase change material.

[0036] Comparative Example 3

[0037] Preparation of a thermally conductive phase change material:

[0038] In parts by weight, 7 parts of dihydroxy-terminated polyisobutylene rubber with a molecular weight of 1500, 1 part of modified phase change wax and 0.1 part of antioxidant BASF 1076 are vacuum stirred at 110°C until they are uniform, then 1 part of hexadecyltrimethoxysilane coupling agent is added and vacuum stirred until they are uniform, and finally 90.9 parts of filler (aluminum oxide with a particle size of 3 μm and zinc oxide with a particle size of 0.5 μm in a mass ratio of 3:1) are added and vacuum stirred until they are uniform, to obtain a thermal conductive phase change material.

[0039] The basic performance tests were conducted on the thermally conductive phase change materials obtained in Examples 1-2 and Comparative Examples 1-3, wherein the thermal conductivity was tested using a hot disk, and the thermal resistance was tested using a Ruiling thermal resistance meter, under the test conditions of 80°C and 10psi; the effective area of ​​the thermally conductive phase change material is the area where the thermally conductive phase change material is sandwiched between a silicon wafer and an aluminum plate and is not pumped out after 1000 cycles at -40°C-125°C. The basic performance test results are shown in Table 1; the pictures of the thermally conductive phase change material prepared in Example 1 after 1000 cycles are shown in Table 1. Figure 1 As shown; Comparative Example 1 uses the thermal conductive phase change material prepared by unmodified phase change wax after 1000 cycles of temperature cycling as shown Figure 2 shown.

[0040] Table 1. Basic performance test

[0041]

[0042] The basic performance test results in Table 1 show that Examples 1-2 use modified phase change wax and reasonably match the ratio between the base resin and the modified phase change wax to obtain a thermally conductive phase change material with both low thermal resistance and low pumping out. Although the thermally conductive phase change material prepared in Comparative Example 1 has low thermal resistance, the interaction between the unmodified phase change wax and the base resin is very weak, and it is easy to pump out during the temperature cycle. Although the thermally conductive phase change material prepared in Comparative Example 2 has excellent anti-pumping performance, the use of too much modified phase change wax results in a high degree of cross-linking in the system, and the poor fluidity after heating leads to high thermal resistance. The thermally conductive phase change material prepared in Comparative Example 3 has too low a content of modified phase change wax, which cannot effectively reduce the viscosity of the system, resulting in high thermal resistance.

[0043] from Figure 1 and Figure 2 It can be seen that the thermal conductive phase change material prepared in Example 1 has only a small amount of micro-crack pumping out area after temperature cycling, while the thermal conductive phase change material prepared in Comparative Example 1 has multiple wider strip-shaped pumping out areas after temperature cycling.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A low thermal resistance and low pump-out thermal conductive phase change material, characterized in that: The composition comprises the following components in parts by weight: 2-15 parts of base resin, 1-3 parts of modified phase change wax, 90-95 parts of filler, 0.5-2 parts of coupling agent, 0.1-0.5 parts of antioxidant; The base resin is a dihydroxy-terminated polyolefin; the modified phase-change wax is a phase-change wax grafted with maleic anhydride groups.

2. The low thermal resistance and low pump-out thermal conductive phase change material according to claim 1, characterized in that: The dihydroxy-terminated polyolefin is one or a mixture of dihydroxy-terminated polyisobutylene, dihydroxy-terminated polybutadiene, dihydroxy-terminated polybutylene, and dihydroxy-terminated ethylene-propylene rubber.

3. The low thermal resistance and low pump-out thermal conductive phase change material according to claim 1, characterized in that: The preparation method of the modified phase change wax is as follows: the phase change wax is dissolved in xylene, and then maleic anhydride is added to carry out graft polymerization under the action of an initiator to obtain the modified phase change wax.

4. The low thermal resistance and low pump-out thermal conductive phase change material according to claim 2, characterized in that: The molecular weight of the dihydroxy-terminated polyolefin is 1000-2000.

5. The low thermal resistance and low pump-out thermal conductive phase change material according to claim 3, characterized in that: The phase change wax is a solid paraffin with a melting point of 40°C-70°C.

6. The low thermal resistance and low pump-out thermal conductive phase change material according to claim 1, characterized in that: The filler is a ceramic filler and / or a metal filler.

7. The low thermal resistance and low pump-out thermal conductive phase change material according to claim 6, characterized in that: The ceramic filler is one or more of aluminum oxide, aluminum nitride, silicon nitride, and zinc oxide; the metal filler is one or more of silver powder, aluminum powder, and copper powder.

8. The low thermal resistance and low pump-out thermal conductive phase change material according to claim 1, characterized in that: The coupling agent is one or more of a silane coupling agent, a titanate coupling agent, a phosphate coupling agent, and a borate coupling agent.

9. The low thermal resistance and low pump-out thermal conductive phase change material according to claim 1, characterized in that: The antioxidant is one or more of BASF 1010, 1076, and 1098.

10. A method for preparing a low thermal resistance and low pump-out thermal conductive phase change material according to any one of claims 1 to 9, characterized in that: The steps include: The base resin, modified phase change wax and antioxidant are vacuum stirred at 100-120°C until they are uniform, then the coupling agent is added and vacuum stirred until they are uniform, and finally the filler is added and vacuum stirred until they are uniform, thereby obtaining a low thermal resistance and low pump-out thermal conductive phase change material.

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