A phase change material matrix for preparing a thermal interface material and a preparation method and application thereof

Abstract

The application provides a phase change material matrix for preparing a thermal interface material and a preparation method and application thereof. The phase change material matrix for preparing the thermal interface material comprises the following components in parts: 0.1-99.9 parts of an olefin material, 0-99.9 parts of a graftable high molecular prepolymer, 0.1-99.9 parts of a crosslinked high molecular prepolymer, and 0.1-1 parts of a catalyst. Under the condition of the same filler parts, the thermal interface material prepared by using the phase change characteristic high molecular matrix has a thermal conductivity increased by 28.6%, a contact thermal resistance reduced by 46.1%, and a storage modulus reduced by 93.33% compared with the thermal interface material of the same type but not prepared by using the matrix. The preparation method is simple and suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of materials technology, specifically to a phase change material matrix that can be used to prepare thermal interface materials, its preparation method, and its application. Background Technology

[0002] Thermal interface materials play a "thermal bridge" role in electronic devices such as packaged chips and device thermal management technologies. They fill the gaps between heat sources and various thermal management components, establishing thermal transport bridges that enable packaged chips to dissipate heat promptly, ensuring efficient operation and extending their lifespan. The key factor in measuring the thermal transport efficiency of thermal interface materials is the material's effective total thermal resistance, which is expressed as follows:

[0003] R total =R contact1 +R contact2 +d / k

[0004] Where R total For effective total thermal resistance; R contact1,2 Let denoted as , where is the interfacial contact thermal resistance between the thermal interface material and the contacting solid; k is the intrinsic thermal conductivity of the thermal interface material; and d is the thickness of the thermal interface material. The equation shows that increasing the material's intrinsic thermal conductivity (k) and reducing the contact thermal resistance are key to improving the thermal transport efficiency of the thermal interface material, i.e., enhancing its thermal conductivity. In recent years, many polymer composite materials have been designed as thermal interface materials to improve thermal conductivity and thus reduce thermal resistance. These thermal interface materials employ strategies such as increasing filler content to form a three-dimensional thermal conduction network, filler hybridization, and surface modification. In fact, an ideal thermal interface material not only needs to possess extremely high thermal conductivity but also good shape adaptability and interfacial compatibility to ensure perfect adhesion at the interface, reduce interfacial contact thermal resistance, and enable effective heat transport across the interface.

[0005] An effective method to improve the interfacial compatibility of thermal interface materials is to reduce the material modulus. Phase change materials (PCMs) can be used as matrices for thermal interface materials due to their significant modulus change before and after the phase change. When the thermal interface material is at high temperature, the matrix undergoes a phase change, the modulus decreases, and the interfacial compatibility is enhanced under the same pressure, thereby improving thermal conductivity at the interface. However, traditional PCMs are solid-liquid phase changes, which can easily lead to liquefaction and leakage during application, affecting the material's thermal conductivity and even damaging electronic devices. Therefore, preventing material liquefaction and leakage is a significant challenge in the development of PCM thermal interface materials. Summary of the Invention

[0006] This invention provides a phase change material matrix for preparing thermal interface materials, its preparation method, and its application. The aim is to solve the interfacial compatibility problem between the thermal interface material and the contacting object, enabling the thermal interface material to adhere more closely at the interface, thereby reducing interfacial contact thermal resistance and improving thermal conductivity.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] The present invention provides a phase change material matrix that can be used to prepare thermal interface materials, comprising the following components in parts: 0.1 to 99.9 parts of olefin material, 0 to 99.9 parts of graftable polymer prepolymer, 0.1 to 99.9 parts of crosslinked polymer prepolymer, and 0.1 to 1 part of catalyst.

[0009] Furthermore, the olefin material is a hexadecene and / or octadecene material with phase change properties.

[0010] Furthermore, the graftable polymer prepolymer is a hydrogen-containing silicone oil that can undergo an addition reaction with olefin materials.

[0011] Furthermore, the cross-linked polymer prepolymer is a polydimethylsiloxane prepolymer.

[0012] Furthermore, the catalyst is selected from at least one of chloroplatinic acid, chloroplatinic acid-isopropanol complex, and chloroplatinic acid-divinyltetramethyldisiloxane complex.

[0013] The present invention also provides a method for preparing the phase change material matrix that can be used to prepare thermal interface materials, the method comprising: uniformly mixing and stirring an olefin material, a graftable polymer prepolymer, a crosslinked polymer prepolymer, and a catalyst to obtain a phase change material matrix that can be used to prepare thermal interface materials; wherein, in this method, after the olefin material is grafted with the graftable polymer prepolymer, it is further crosslinked with the crosslinked polymer prepolymer to form a covalent network; or, after the olefin material is grafted with the graftable polymer prepolymer, it is dissolved in the crosslinked polymer prepolymer and self-crosslinked to form a covalent network.

[0014] Furthermore, the polymeric prepolymer after grafting the olefin material exists in the matrix in the form of crosslinking with other polymeric prepolymers or being dispersed in a polymeric crosslinking network, or both.

[0015] The present invention also provides a method for preparing the phase change material matrix that can be used to prepare thermal interface materials, the method comprising: uniformly mixing and stirring an olefin material, a cross-linked polymer prepolymer, and a catalyst to obtain a phase change material matrix that can be used to prepare thermal interface materials; wherein, in this method, the olefin material and the cross-linked polymer prepolymer are directly cross-linked.

[0016] The present invention further provides the application of the above-mentioned phase change material matrix for preparing thermal interface materials in the field of preparing thermal interface materials.

[0017] Furthermore, the thermal interface material has a thermal conductivity ranging from 0.1 W / mK to 100.0 W / mK, and the contact heat exchanger has a capacity of 10. - 7 m 2 K / W ~ 10 -4 m 2 K / W, modulus in the range of 0.001KPa to 1000MPa.

[0018] Compared with the prior art, the technical solution provided by the present invention has at least the following advantages:

[0019] This invention provides a phase change material matrix for preparing thermal interface materials, its preparation method, and its applications. Under the same filler content, the thermal interface material prepared using this phase change material matrix exhibits a 28.6% increase in thermal conductivity, a 46.1% decrease in contact thermal resistance, and a 93.33% decrease in storage modulus compared to similar materials prepared without this matrix. Furthermore, the preparation method is simple and suitable for industrial production. Attached Figure Description

[0020] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments, and unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0021] Figure 1 These are polymer matrices prepared using different methods in the embodiments of the present invention;

[0022] Figure 2 These are polymer matrices prepared using different methods in the embodiments of the present invention;

[0023] Figure 3 These are polymer matrices prepared using different methods in the embodiments of the present invention;

[0024] Figure 4 This is an example of an embodiment of the invention using an Olympus polarizing microscope to observe the state of the matrix before and after the phase transition following crosslinking. Detailed Implementation

[0025] The inventors discovered that improving the modulus of thermal interface materials can enhance material interface compatibility; selecting a suitable polymer matrix can effectively adjust the modulus of thermal interface materials; phase change materials can be used as a matrix to prepare thermal interface materials due to the significant change in modulus before and after phase change; however, pure phase change materials such as paraffin wax will liquefy after phase change, leading to material leakage.

[0026] Based on this, silicone oils with phase change properties are synthesized by grafting olefin materials with hydrogen-containing side chains onto olefin materials with phase change properties. The synthesized silicone oil is then used as a polymer monomer to covalently crosslink with other polymer prepolymers, such as dimethylsiloxane, to form a crosslinked network, resulting in a polymer colloid with solid-solid phase change properties and a significant modulus change. Alternatively, the synthesized phase change silicone oil can be mixed and crosslinked with other self-crosslinking silicone oil polymer prepolymers. The silicone oil polymer prepolymers crosslink to form a covalent network. Since the structure of the phase change silicone oil is similar to that of the crosslinked silicone oil, according to the principle of "like dissolves like," the phase change silicone oil can be effectively locked by the covalent network of the crosslinked silicone oil, thus preventing leakage. By uniformly mixing the above-mentioned uncrosslinked raw materials in different proportions with high thermal conductivity fillers and then performing a heat-curing crosslinking treatment, a thermal interface material with solid-solid phase change properties, improved material modulus, and enhanced interfacial compatibility can be obtained.

[0027] The present invention provides a phase change material matrix that can be used to prepare thermal interface materials, comprising the following components in parts: 0.1 to 99.9 parts of olefin material, 0 to 99.9 parts of graftable polymer prepolymer, 0.1 to 99.9 parts of crosslinked polymer prepolymer, and 0.1 to 1 part of catalyst.

[0028] This invention also provides a method for preparing a phase change material matrix that can be used to prepare thermal interface materials, as described above. Figure 1 , Figure 3 As shown, the method includes: uniformly mixing and stirring an olefin material, a graftable polymer prepolymer, a crosslinked polymer prepolymer, and a catalyst to obtain a phase change material matrix that can be used to prepare thermal interface materials; wherein, in this method, after the olefin material is grafted onto the graftable polymer prepolymer, it is then crosslinked with the crosslinked polymer prepolymer to form a covalent network; or, after the olefin material is grafted onto the graftable polymer prepolymer, it is dispersed in the covalent network formed by the self-crosslinking of the crosslinked polymer prepolymer. Figure 3 The green areas indicate the possible locations where the grafted polymer prepolymer may be dispersed.

[0029] It should be noted that, in this invention, the first case is as follows: Figure 1 As shown, the grafted polymer prepolymer reacts with the cross-linked polymer prepolymer to form a polymer cross-linking network after being grafted onto an olefin material. In other words, the grafted polymer prepolymer is part of the polymer cross-linking composition. Alternatively, "dissolved" means the grafted prepolymer does not react with the cross-linked prepolymer and is dispersed as a monomer solution within the polymer cross-linking network formed by the cross-linked polymer prepolymer. This can be compared to a hydrogel, where water is dispersed within the gel network, i.e., dissolved. The grafted prepolymer is dispersed within the cross-linking network, i.e., dissolved, as... Figure 3 The green area is shown.

[0030] This invention also provides a method for preparing the phase change material matrix described above, which can be used to prepare thermal interface materials, such as... Figure 2 As shown, the method includes: uniformly mixing and stirring an olefin material, a cross-linked polymer prepolymer, and a catalyst to obtain a phase change material matrix that can be used to prepare thermal interface materials; wherein, in this method, the olefin material and the cross-linked polymer prepolymer are directly cross-linked.

[0031] The present invention further provides the application of the above-mentioned phase change material matrix for preparing thermal interface materials in the field of preparing thermal interface materials.

[0032] The present invention will now be described in detail with reference to specific embodiments. It should be noted that, in the following embodiments, the unit referred to as "parts" is "parts by mass" unless otherwise specified.

[0033] Example 1

[0034] (A) 4.4 parts by mass of side-chain hydrogen-containing silicone oil and 11.6 parts by mass of hexadecene were subjected to a progressive addition reaction to obtain 16 parts by mass of grafted hexadecene side-chain hydrogen-containing silicone oil for later use. This synthetic operation is a well-known part and need not be described in detail.

[0035] (B) 80 parts of thermally conductive filler, 16 parts of grafted hexadecene side-chain hydrogen-containing silicone oil, and 4 parts of polydimethylsiloxane prepolymer are added to a high-speed mixer and stirred at room temperature and high speed. The specific parameters can be set as follows: stir at 1000 rpm for 60 seconds, then stir at 1200 rpm for 45 seconds, then stir at 1500 rpm for 30 seconds, and finally stir at 1800 rpm for 15 seconds.

[0036] (C) After thorough stirring, add 0.1 parts of chloroplatinic acid-divinyltetramethyldisiloxane complex.

[0037] (D) At 20°C and a vacuum of -90.0 kPa, continue stirring at 1000 rpm for 45 seconds, then at 1200 rpm for 30 seconds, and then at 1500 rpm for 15 seconds.

[0038] (E) Take out the above mixture and roll it into different thicknesses.

[0039] (F) Test after heat curing for later use.

[0040] Example 2

[0041] The operation is basically the same as in Example 1, except that the number of parts of the synthetic materials is changed to 80 parts by mass of thermally conductive filler, 14 parts of grafted hexadecene side-chain hydrogen-containing silicone oil (3.8 parts of side-chain hydrogen-containing silicone oil and 10.2 parts of hexadecene), and 6 parts of polydimethylsiloxane prepolymer.

[0042] Example 3

[0043] The operation is basically the same as in Example 1, except that the proportions of the synthetic materials are changed to 80 parts by mass of thermally conductive filler, 12 parts of grafted hexadecene side-chain hydrogen-containing silicone oil (3.3 parts of side-chain hydrogen-containing silicone oil and 8.7 parts of hexadecene), and 8 parts of polydimethylsiloxane prepolymer.

[0044] Example 4

[0045] The operation is basically the same as in Example 1, except that the proportions of the synthetic materials are changed to 80 parts by mass of thermally conductive filler, 10 parts of grafted hexadecene side-chain hydrogen-containing silicone oil (2.7 parts of side-chain hydrogen-containing silicone oil and 7.3 parts of hexadecene), and 10 parts of polydimethylsiloxane prepolymer.

[0046] Comparative Example 1

[0047] The operation is basically the same as in Example 1, except that the number of parts of the synthetic material is changed to 80 parts by mass of thermally conductive filler and 20 parts of polydimethylsiloxane prepolymer.

[0048] (1) Thermal conductivity test of thermal interface materials:

[0049] The intrinsic thermal conductivity and contact thermal resistance of the material were tested using the Ruiling thermal conductivity tester (LW9389). The test was conducted according to ASTM D 5470, which is a well-known standard and will not be elaborated upon here.

[0050] The thermal conductivity and contact thermal resistance of the obtained thermal interface materials were tested according to the above method in Examples 1-4 and Comparative Example 1. The results are shown in the table below.

[0051]

[0052] (2) Material mechanical strength test:

[0053] The material was tested at high and low temperatures (room temperature and 75℃) using a universal tensile testing machine (Shimadzu, Japan, model AG-X plus 10N-10kN). The testing method is well-known and will not be elaborated upon here. The tensile rate was set to 3 mm / min.

[0054] The tensile strength and elongation at break of Examples 1-4 were tested according to the above method. The test results are summarized in the table below:

[0055]

[0056] (3) Leakage rate test:

[0057] The leakage rate was determined by placing an initial mass M0 of sample on filter paper in an oven maintained at 60°C. After one hour, the sample was removed and weighed using an analytical balance, with the filter paper replaced after each weighing. The mass of the sample after being heated in the oven n times was defined as M.n The formula for calculating the material leakage rate is as follows:

[0058] L=(M0-M n ) / M0×100%

[0059] Final leakage rate (%) after 24 hours Example 4 0.754 Example 3 0.837 Example 2 0.885 Example 1 0.916

[0060] (4) Material modulus test:

[0061] The material storage modulus was tested using a dynamic thermomechanical analyzer (DMA) in the temperature range of 0–80 °C at a heating rate of 2 °C per minute.

[0062] Furthermore, the changes in modulus of Examples 1-4 with increasing temperature were tested using the above method, and the test results are summarized in the table below:

[0063]

[0064] (5) The state of the matrix before and after the phase transition following crosslinking was observed using an Olympus polarizing microscope, such as... Figure 4 As shown, from Figure 4 As can be seen, the olefin molecular chains undergo a phase transition in situ upon grafting. Due to the restriction of covalent bonds, the olefin molecular chains are in a non-free state, which prevents them from aggregating and precipitating before and after the phase transition. Repeated heating and cooling operations confirm this characteristic, thus proving that the polymer matrix has stable solid-solid phase transition characteristics.

[0065] Those skilled in the art will understand that the above-described embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of this application. Any person skilled in the art can make their own modifications and alterations without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A phase change material matrix useful in the preparation of a thermal interface material, characterized in that, The components include: 0.1-99.9 parts of olefin material, more than 0 and less than or equal to 99.9 parts of graftable high molecular prepolymer, 0.1-99.9 parts of crosslinking high molecular prepolymer, and 0.1-1 parts of catalyst; The phase change material matrix has solid-solid phase change characteristics; The olefin material is a phase change material with hexadecene and / or octadecene; The phase change material matrix for preparing thermal interface material is prepared by the following method, which comprises: The olefin material, the graftable high molecular prepolymer, the crosslinking high molecular prepolymer, and the catalyst are uniformly mixed and stirred to obtain the phase change material matrix for preparing thermal interface material; In the method, the olefin material is grafted with the graftable high molecular prepolymer, and then crosslinked with the crosslinking high molecular prepolymer to form a covalent bond network. Alternatively, the olefin material is grafted with the graftable high molecular prepolymer, and then dissolved in the crosslinking high molecular prepolymer to form a covalent bond network after self-crosslinking. The graftable high molecular prepolymer is a hydrogen-containing silicone oil capable of addition reaction with the olefin material. The crosslinking high molecular prepolymer is a polydimethylsiloxane prepolymer.

2. The phase change material matrix useful for preparing a thermal interface material according to claim 1, wherein, The catalyst is selected from at least one of chloroplatinic acid, chloroplatinic acid-isopropyl alcohol complex, and chloroplatinic acid-divinyltetramethyldisiloxane complex.

3. The phase change material matrix useful for preparing a thermal interface material according to claim 1, wherein, The graftable high molecular prepolymer after grafting the olefin material exists in the matrix in the form of crosslinking with other high molecular prepolymers, dispersion in a high molecular crosslinking network, or both.

4. The method for producing a phase change material matrix for a thermal interface material according to any one of claims 1 to 3, characterized in that, The method comprises: The olefin material, the graftable high molecular prepolymer, the crosslinking high molecular prepolymer, and the catalyst are uniformly mixed and stirred to obtain the phase change material matrix for preparing thermal interface material; In the method, the olefin material is directly crosslinked with the crosslinking high molecular prepolymer.

5. Use of the phase change material matrix for preparing thermal interface material according to any one of claims 1-3 in the field of preparing thermal interface material.

6. Use of a phase change material matrix for the preparation of a thermal interface material according to claim 5, characterized in that, The thermal conductivity of the thermal interface material is 0.1 W / mK~100.0 W / mK, the contact thermal resistance is 10 -7 m 2 K / W ~ 10 -4 m 2 K / W, and the modulus is in the range of 0.001 KPa~1000 MPa.

Images