PVC composite heat-conducting gasket, preparation method thereof and PVC composite heat-conducting gasket obtained

Abstract

This invention discloses a PVC composite thermal conductive pad, its preparation method, and the resulting PVC composite thermal conductive pad. The pad comprises a matrix material and a filler. The matrix material includes PVC material, an organic solvent, a plasticizer, and a filler selected from one or more of aluminum nitride (AlN), boron nitride (BN), alumina (Al2O3) ceramic particles, silicon nitride (Si4N3), and silicon carbide (SiC). The PVC composite thermal conductive pad does not experience oil seepage or drying out during prolonged high-temperature use. Furthermore, it exhibits good viscoelasticity and stable thermal conductivity at high temperatures.

Description

Technical Field

[0001] This invention pertains to polymer composite materials, specifically relating to a PVC composite thermal conductive pad, its preparation method, and the resulting PVC composite thermal conductive pad. Background Technology

[0002] With the continuous development of high technology, the power of electronic components is constantly increasing, leading to a gradual increase in the heat generated by components such as chips and semiconductor lasers. This places higher demands on thermal interface materials (TIMs) to meet future TIM usage requirements. TIMs are soft and wettable materials that deform under contact pressure to fill gaps and improve heat transfer in electronic packaging. Currently, the base of thermal paste is mainly silicone oil, but it is prone to oiling at high temperatures and has poor thermal conductivity (<10W / (m·K)), limiting its use. Thermal adhesives are thermosetting polymer materials with excellent thermal conductivity that are cured to achieve encapsulation of electronic components and good interfacial bonding with heat sink materials. Thermal phase change materials transfer heat by changing from a solid to a liquid state, but they are not easy to seal in liquid form and are prone to anodizing and corrosion of circuit boards, limiting their use. Thermal pads are soft and elastic sheet-like thermal interface materials that fill the uneven gaps between heat-generating and heat-dissipating components to achieve effective heat transfer. At the same time, thermal pads also play a role in sealing, shock absorption, and insulation.

[0003] For thermal pads, silicone oil is currently the main component. However, silicone oil is prone to continuous leakage when used continuously in high-temperature environments, which can easily damage chips and circuit components. Particles and impurities around the chip can be adsorbed or adhered to the leaked oil, causing short circuits. Furthermore, the leakage can create gaps in the contact between the chip and components such as heat sinks and heat pipes, resulting in reduced heat dissipation capacity.

[0004] Secondly, silicone-based thermal pads can dry out during use. This is mainly because under continuous use and high temperatures, silicone oil, dispersants, coupling agents, and inhibitors can fail and deteriorate. Furthermore, continuous oil seepage can cause the internal thermally conductive filler to accumulate and solidify. Drying of the thermal pad increases the gap between the chip and the heat sink, resulting in poor heat dissipation, increased chip malfunction, and reduced lifespan. Patent CN1880399A describes the preparation of a thermally conductive adhesive using polyethylene as the matrix and diethyl ether and toluene as solvents, but the absence of a plasticizer fails to address the poor thermal stability of polyethylene.

[0005] In existing thermal pads, metal powders, such as aluminum powder and copper powder, and graphite materials, such as carbon nanotubes, graphene, and carbon nanofibers, are often used as thermal fillers. However, when oil seeps in or the thermal pad dries out, the accumulation of various powders can make them conductive, which can lead to short circuits in the chip and damage the chip. Summary of the Invention

[0006] To overcome the problems existing in the prior art, the present invention provides a PVC composite thermal conductive pad, its preparation method and the obtained PVC composite thermal conductive pad. The PVC composite thermal conductive pad will not cause problems such as oil seepage or drying out when used at high temperatures for a long time. In addition, it has good viscoelasticity and stable thermal conductivity at high temperatures.

[0007] One objective of this invention is to provide a PVC composite thermally conductive pad, which includes a matrix material and a filler, wherein the matrix material includes PVC material, organic solvent, plasticizer and filler.

[0008] PVC refers to polyvinyl chloride.

[0009] In a preferred embodiment, the PVC material has a molecular weight of 20,000 to 200,000, preferably 50,000 to 120,000. The polyvinyl chloride has the structure -(CH2-CHCl). n - is a single-chain structure with a high degree of polymerization (n). This type of single-chain structure has a relatively good thermal conductivity.

[0010] The molecular weight of the polyvinyl chloride is any point value or a range of any two point values ​​of 20,000, 30,000, 50,000, 60,000, 70,000, 80,000, 90,000, 100,000, 110,000, 120,000, 140,000, 160,000, 180,000 or 200,000.

[0011] In a preferred embodiment, the organic solvent is selected from at least one of tetrahydrofuran, cyclohexanone, dichloroethane, tetrahydropyran, chloroform, carbon tetrachloride, and xylene.

[0012] In a further preferred embodiment, the organic solvent is tetrahydrofuran.

[0013] Tetrahydrofuran, with the molecular formula C4H8O, is an excellent nonpolar solvent, particularly suitable for dissolving PVC. It has a 5-membered ring structure and a unique CO bond. However, tetrahydrofuran differs from ethers in that it has low toxicity and is widely applicable to the dissolution of organic compounds.

[0014] In a preferred embodiment, the plasticizer is selected from at least one of diisooctyl sebacate (DOS), dibutyl phthalate (DBP), dioctyl phthalate (DOP), 2-nitrophenyl octyl ether (NPOE), (2-ethylhexyl) phthalate (DEHP), and diethyl phthalate (DEP).

[0015] In a further preferred embodiment, the plasticizer is dibutyl phthalate (DBP).

[0016] Among them, dibutyl phthalate has the molecular formula C 16 H 22 O4 and DBP contain benzene rings and ester bonds. Organic solvents, especially tetrahydrofuran, can mutually dissolve the hydrophobic groups in dibutyl phthalate, exhibiting good solubility, dispersibility, and adhesion. Specifically, the viscosities of DBP, DOS, DOP, and DEHP are 16.3 mPa·s, 25 mPa·s, 80 mPa·s, and 81 mPa·s, respectively. Among them, DBP has the lowest viscosity and the lowest molecular weight (278). The matrix formed by the low-viscosity plasticizer can increase the filling ratio of the filler in the matrix when mixed with powders of different particle sizes, and the low viscosity will not cause agglomeration between particles. Therefore, DBP is the preferred choice.

[0017] Specifically, PVC material is first dissolved in an organic solvent to form a low-viscosity liquid system. If the filler is added under these conditions, it may not disperse well in the system, potentially leading to aggregation or even precipitation, thus affecting the performance of the thermal pad. Therefore, to further improve the performance of the thermal pad, the inventors discovered through extensive experimentation that adding a plasticizer to the liquid system can increase its viscosity. The plasticizer surrounds the filler, allowing it to disperse well in the liquid system, thereby improving its performance.

[0018] In this invention, if too little organic solvent is added, the PVC will not be completely dissolved, which will affect the dispersion between the matrix and the filler, reduce its thermal conductivity, and easily cause cracks in the PVC particles during use, resulting in failure and damage.

[0019] In a preferred embodiment, the filler is selected from one or more of aluminum nitride (AlN), boron nitride (BN), alumina (Al2O3) ceramic particles, silicon nitride (Si4N3), and silicon carbide (SiC), such as aluminum nitride (AlN).

[0020] In a preferred embodiment, the filler is spherical powder with a variety of different particle sizes.

[0021] In a further preferred embodiment, the different particle sizes include four or more of the following: 8–12 μm, 4–7 μm, 2–3 μm, 0.8–1.5 μm, 0.4–0.7 μm, 0.2 μm, and 0.1 μm (e.g., four or more of the following: 10 μm, 5 μm, 2 μm, 1 μm, 0.5 μm, 0.2 μm, and 0.1 μm), preferably including 4–7 μm, 2–3 μm, and 0.4–7 μm. Four or more of the following materials are used: 0.8–1.5 μm, 0.4–0.7 μm, 0.2 μm and 0.1 μm (e.g., four or more of the following materials are used: 5 μm, 2 μm, 1 μm, 0.5 μm, 0.2 μm and 0.1 μm), more preferably 4–7 μm, 0.8–1.5 μm, 0.4–0.7 μm and 0.1 μm (e.g., 5 μm, 1 μm, 0.5 μm and 0.1 μm).

[0022] In a further preferred embodiment, the different particle sizes include 0.8–1.5 μm, 0.4–0.7 μm, and 0.1 μm, and optionally include one, two, or three of the following: 8–12 μm, 4–7 μm, and 2–3 μm.

[0023] Wherein, "8~12μm" can be 8μm, 9μm, 10μm, 11μm or 12μm, "4~7μm" can be 4μm, 5μm, 6μm or 7μm, "2~3μm" can be 2μm or 3μm, "0.8~1.5μm" can be 0.8μm, 1μm, 1.2μm, 1.4μm or 1.5μm, and "0.4~0.7μm" can be 0.4μm, 0.5μm, 0.6μm or 0.7μm.

[0024] This invention employs a gradation of fillers with various particle sizes. This allows larger particle sizes (e.g., 5 μm) to form a support within the matrix, while smaller particle sizes fill the spaces between them, creating a three-dimensional thermal conductive pathway. Furthermore, through extensive experimentation, the inventors discovered that using fillers with particle sizes larger than 12 μm can result in a harder thermally conductive pad, whereas the fillers composed of the different particle sizes defined above in this invention produce a softer thermally conductive pad.

[0025] In a preferred embodiment, when the filler comprises four different particle sizes (e.g., four of the following: 8–12 μm, 4–7 μm, 2–3 μm, 0.8–1.5 μm, 0.4–0.7 μm, 0.2 μm, and 0.1 μm, or four of the following: 4–7 μm, 2–3 μm, 0.8–1.5 μm, 0.4–0.7 μm, 0.2 μm, and 0.1 μm), the proportions of the four different particle sizes, from largest to smallest, are 5–10 wt% (e.g., 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, or 10 wt%), 15–25 wt%, respectively. t% (e.g., 15wt%, 16wt%, 18wt%, 20wt%, 22wt%, 24wt% or 25wt%), 25-40wt% (e.g., 25wt%, 28wt%, 30wt%, 32wt%, 34wt%, 36wt%, 38wt% or 40wt%), 30-55wt% (e.g., 30wt%, 32wt%, 34wt%, 36wt%, 38wt%, 40wt%, 42wt%, 44wt%, 46wt%, 48wt%, 50wt%, 52wt%, 54wt% or 55wt%).

[0026] In a further preferred embodiment, when the different particle sizes include 4–7 μm, 0.8–1.5 μm, 0.4–0.7 μm, and 0.1 μm, based on 100 wt% of the filler, the filler with 4–7 μm accounts for 5–10 wt%, the filler with 0.8–1.5 μm accounts for 15–25 wt%, the filler with 0.4–0.7 μm accounts for 25–40 wt%, and the filler with 0.1 μm accounts for 30–55 wt%.

[0027] For example, the proportion of fillers with a diameter of 4–7 μm is 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, or 10 wt%; the proportion of fillers with a diameter of 0.8–1.5 μm is 15 wt%, 16 wt%, 18 wt%, 20 wt%, 22 wt%, 24 wt%, or 25 wt%; the proportion of fillers with a diameter of 0.4–0.7 μm is 25 wt%, 28 wt%, 30 wt%, 32 wt%, 34 wt%, 36 wt%, 38 wt%, or 40 wt%; and the proportion of fillers with a diameter of 0.1 μm is 30 wt%, 32 wt%, 34 wt%, 36 wt%, 38 wt%, 40 wt%, 42 wt%, 44 wt%, 46 wt%, 48 wt%, 50 wt%, 52 wt%, 54 wt%, or 55 wt%.

[0028] In a preferred embodiment, the base material accounts for 20-60 wt% and the filler accounts for 40-80 wt% of 100 wt% of the thermal pad.

[0029] In a further preferred embodiment, the base material accounts for 30-50 wt% and the filler accounts for 50-70 wt% of 100 wt% of the thermal pad.

[0030] For example, based on 100 wt% of the thermally conductive pad, the matrix material accounts for 20 wt%, 30 wt%, 40 wt%, 50 wt%, or 60 wt%, and the filler accounts for 40 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, or 80 wt%.

[0031] In a preferred embodiment, based on 100 wt% of the matrix material, the PVC material accounts for 15-50 wt%, the organic solvent accounts for 5-40 wt%, and the plasticizer accounts for 30-65 wt%.

[0032] In a further preferred embodiment, based on 100 wt% of the matrix material, the PVC material accounts for 20-40 wt%, the organic solvent accounts for 10-30 wt%, and the plasticizer accounts for 40-60 wt%.

[0033] For example, based on 100 wt% of the matrix material, the PVC material accounts for 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, or 50 wt%, the organic solvent accounts for 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, or 50%, and the plasticizer accounts for 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, or 65 wt%.

[0034] In this invention, polyvinyl chloride (PVC) is used as a carrier, an organic solvent is added, and a plasticizer is used to obtain a uniform and stable polymer blend. The polymers are mainly bonded by physical interaction. PVC and plasticizer form a polyvinyl chloride gel, which can have good interfacial bonding with the filler. In addition, fillers of different particle sizes can form a 3D heat transfer network in the system, improving the thermal conductivity of the thermal pad.

[0035] The second objective of this invention is to provide a method for preparing the PVC composite thermal conductive pad described in the first objective of this invention, comprising: mixing raw materials including the PVC material, the organic solvent, the plasticizer and the filler, and molding them into the PVC composite thermal conductive pad.

[0036] In a preferred embodiment, the preparation method includes: (1) mixing the PVC material, the organic solvent, and the plasticizer to form a dispersion liquid one; (2) adding the uniformly mixed filler into the dispersion liquid one and stirring to obtain a dispersion liquid two; (3) molding the dispersion liquid two to obtain the thermally conductive pad.

[0037] In a preferred embodiment, in step (1), based on a total amount of 100wt% of the PVC material, the organic solvent, and the plasticizer, the PVC material accounts for 15-50wt%, the organic solvent accounts for 5-40wt%, and the plasticizer accounts for 30-65wt%.

[0038] In a further preferred embodiment, in step (1), based on a total amount of 100wt% of the PVC material, the organic solvent, and the plasticizer, the PVC material accounts for 20-40wt%, the organic solvent accounts for 10-30wt%, and the plasticizer accounts for 40-60wt%.

[0039] In a preferred embodiment, in step (1), the PVC material is first mixed with the organic solvent and stirred, then the plasticizer is added and stirred to obtain the dispersion.

[0040] In a further preferred embodiment, the plasticizer is added dropwise.

[0041] Adding plasticizer drop by drop allows for a more complete reaction between the plasticizer and the system.

[0042] In a preferred embodiment, based on 100wt% of the PVC material, the organic solvent, the plasticizer, and the filler, the PVC material, the organic solvent, and the plasticizer together account for 20-60wt%, and the filler accounts for 40-80wt%.

[0043] In a further preferred embodiment, based on 100wt% of the PVC material, the organic solvent, the plasticizer, and the filler, the PVC material, the organic solvent, and the plasticizer together account for 30-50wt%, and the filler accounts for 50-70wt%.

[0044] In a preferred embodiment, the uniformly mixed filler in step (2) is mixed by ball milling.

[0045] In a further preferred embodiment, the uniformly mixed filler in step (2) is obtained as follows: multiple fillers of different particle sizes are mixed in proportion and then placed in a ball mill jar filled with protective gas for ball milling to obtain the uniformly mixed filler.

[0046] The various fillers with different particle sizes and their dosages have been described previously and will not be repeated here. Preferably, the protective gas is selected from at least one of inert gases and nitrogen, and more preferably from at least one of argon and nitrogen.

[0047] In a further preferred embodiment, in the ball mill, the mass ratio of the filler to the grinding balls is 1:(1-6), preferably 1:(2-5), for example 1:1, 1:2, 1:3, 1:4, 1:5 or 1:6.

[0048] In this process, ball milling ensures that filler powders of different particle sizes are evenly distributed and do not agglomerate, thereby obtaining a well-graded mixed powder.

[0049] In this invention, the mixing or stirring in steps (1) and (2) is preferably carried out by mechanical stirring, such as by using a cantilever stirrer. It is preferable to mix or stir evenly in steps (1) and (2), especially in step (2), it is preferable to stir evenly so that the filler powder is evenly dispersed in the dispersion liquid and to avoid powder agglomeration.

[0050] In a preferred embodiment, the molding process is performed in a mold, such as a silicone mold.

[0051] In a further preferred embodiment, the dispersion liquid II is filled into a mold and pressed or left to stand to form, thereby obtaining the thermally conductive pad.

[0052] In this invention, spherical powder fillers of different particle sizes and mass fractions are mechanically mixed to obtain a mixed powder with uniform particle size distribution. PVC material is dissolved using an organic solvent, then a plasticizer is added, followed by the mixed powder. After thorough mixing, the mixture is placed in a pre-prepared mold and allowed to stand or be pressed to obtain the thermal pad.

[0053] The third objective of this invention is to provide a PVC composite thermally conductive pad obtained by the preparation method described in the second objective of this invention.

[0054] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In the following, various technical solutions can, in principle, be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] (1) Using PVC as a carrier and adding organic solvents and plasticizers can form a uniform and stable polymer blend. Using this as the base of the thermal pad will not cause oil seepage, drying or filler agglomeration during long-term use. This type of thermal pad has good viscoelasticity and can play a role in sealing and shock absorption during use.

[0057] (2) Using solvents and plasticizers, a flexible polyvinyl chloride gel can be formed at room temperature. It has good fluidity, can wet filler powder, and has better viscoelasticity and impact toughness after curing.

[0058] (3) Using spherical filler powders of different particle sizes, the powder obtained by mixing in a ball mill has a uniform particle size distribution and good uniformity, and can form a bridge in the matrix material to form a 3D heat transfer network structure; the PVC composite thermal pad has the potential to be used in high-power chips and semiconductor lasers.

[0059] (4) The PVC composite thermal pad described in this invention has the advantages of high thermal conductivity, low Shore hardness (softness), and non-conductivity. Moreover, its thermal conductivity is more than 15% higher than that of thermal pads with dimethyl silicone oil as the carrier (7.5W / (m·K)), especially more than 20%, and its Shore hardness is below 60, for example below 55. Attached Figure Description

[0060] Figure 1 This is a schematic diagram of the particle size distribution of AlN particles of four different sizes in Example 1.

[0061] Figure 2 This is a schematic diagram of the particle size distribution structure of AlN particles with three different particle sizes in Example 3. Detailed Implementation

[0062] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0063] It should also be noted that the various specific technical features described in the following embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the various possible combinations will not be described separately in this invention.

[0064] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention. The resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0065] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0066]

Example 1

[0067] Weigh out 5μm spherical AlN powder, 1μm spherical AlN powder, 0.5μm spherical AlN powder, and 0.1μm spherical AlN powder according to a mass ratio of 1:2:3:4, with masses of 20.00g, 40.00g, 60.00g, and 80.00g respectively. Place them in a zirconia ball mill jar, add 600g of zirconia grinding balls with a diameter of 5mm, seal with an O-ring before ball milling, evacuate the ball mill jar and fill it with argon gas, and ball mill at a speed of 150r / min with a start / stop interval of 30min for a total of 3h to obtain AlN mixed powder with uniform particle size distribution.

[0068] Weigh out 25.00g of PVC granules with a molecular weight of 80,000 to 100,000, 50.00g of plasticizer DBP, and 25.00g of tetrahydrofuran according to a mass ratio of 1:2:1. Pour the tetrahydrofuran solution into a beaker containing PVC granules and stir it at 100r / min using a cantilever stirrer. After the PVC granules are completely dissolved, add the plasticizer dropwise and stir for 3 hours to obtain dispersion one.

[0069] The uniformly distributed AlN mixed powder obtained above was slowly added to dispersion one, and stirred at 100 r / min for 2 h using a cantilever stirrer to avoid particle agglomeration, thus obtaining dispersion two.

[0070] Pour the prepared dispersion into The AlN / PVC composite thermal pad is obtained by placing the solution in a silicone mold at room temperature and allowing it to solidify naturally.

[0071] The thermal conductivity, resistivity, and hardness of the thermal pad were tested, and the results showed that the thermal conductivity was 9.86 W / (m·K), the Shore hardness was 52, and it was non-conductive. Its thermal conductivity was 31.5% higher than that of the thermal pads currently using dimethyl silicone oil as a carrier (7.5 W / (m·K)).

[0072]

Example 2

[0073] Weigh out 5μm spherical AlN powder, 1μm spherical AlN powder, 0.5μm spherical AlN powder, and 0.1μm spherical AlN powder according to a mass ratio of 1:2:2:5, with masses of 20.00g, 40.00g, 40.00g, and 100.00g respectively. Place them in a zirconia ball mill jar, add 600g of zirconia grinding balls with a diameter of 5mm, seal with an O-ring before ball milling, evacuate the ball mill jar and fill it with argon gas, and ball mill at a speed of 150r / min with a start / stop interval of 30min for a total of 3h to obtain AlN mixed powder with uniform particle size distribution.

[0074] The dispersion was prepared according to the method described in Example 1.

[0075] The uniformly distributed AlN mixed powder obtained in Example 2 was slowly added to the first dispersion, and stirred at 100 r / min for 3 h using a cantilever stirrer to avoid particle agglomeration, thus obtaining the second dispersion.

[0076] Pour the prepared dispersion into The AlN / PVC composite thermal pad is obtained by placing the solution in a silicone mold at room temperature and allowing it to solidify naturally.

[0077] The thermal conductivity, resistivity, and hardness of the thermal pad were tested, and the results showed that the thermal conductivity was 9.34 W / (m·K), the Shore hardness was 48, and it was non-conductive. Its thermal conductivity was 24.5% higher than that of the thermal pads currently using dimethyl silicone oil as a carrier (7.5 W / (m·K)).

[0078]

Example 3

[0079] The AlN mixed powder with uniform particle size distribution was prepared according to the method in Example 1.

[0080] Weigh out 40.00g of PVC granules with a molecular weight of 60,000 to 80,000, 40.00g of plasticizer DBP, and 20.00g of tetrahydrofuran according to a mass ratio of 2:2:1. Pour the tetrahydrofuran solution into a beaker containing PVC granules and stir it at 100r / min using a cantilever stirrer. After the PVC granules are completely dissolved, add the plasticizer dropwise and stir for 3 hours to obtain a dispersion.

[0081] The uniformly distributed AlN mixed powder obtained above was slowly added to dispersion one, and stirred at 100 r / min for 2 h using a cantilever stirrer to avoid particle agglomeration, thus obtaining dispersion two.

[0082] Pour the prepared dispersion into The AlN / PVC composite thermal pad is obtained by placing the solution in a silicone mold at room temperature and allowing it to solidify naturally.

[0083] The thermal conductivity, resistivity, and hardness of the thermal pad were tested, and the results showed that the thermal conductivity was 9.73 W / (m·K), the Shore hardness was 49, and it was non-conductive. Its thermal conductivity was 29.7% higher than that of the thermal pads currently using dimethyl silicone oil as a carrier (7.5 W / (m·K)).

[0084]

Example 4

[0085] The AlN mixed powder with uniform particle size distribution was prepared according to the method in Example 1.

[0086] Weigh out 20.00g of PVC granules with a molecular weight of 80,000 to 100,000, 40.00g of plasticizer DBP, and 40.00g of tetrahydrofuran according to a mass ratio of 1:2:2. Pour the tetrahydrofuran solution into a beaker containing PVC granules and stir it at 100r / min using a cantilever stirrer. After the PVC granules are completely dissolved, add the plasticizer dropwise and stir for 3 hours to obtain a dispersion.

[0087] The uniformly distributed AlN mixed powder obtained above was slowly added to dispersion one, and stirred at 100 r / min for 2 h using a cantilever stirrer to avoid particle agglomeration, thus obtaining dispersion two.

[0088] Pour the prepared dispersion into The AlN / PVC composite thermal pad is obtained by placing the solution in a silicone mold at room temperature and allowing it to solidify naturally.

[0089] The thermal conductivity, resistivity, and hardness of the thermal pad were tested, and the results showed that the thermal conductivity was 9.95 W / (m·K), the Shore hardness was 61, and it was non-conductive. Its thermal conductivity was 32.7% higher than that of the thermal pads currently using dimethyl silicone oil as a carrier (7.5 W / (m·K)).

[0090] Comparative Example 1

[0091] The process of Example 1 was repeated, except that no plasticizer was added.

[0092] The AlN mixed powder with uniform particle size distribution was prepared according to the method in Example 1.

[0093] Weigh out 50.00g of PVC granules and 50.00g of tetrahydrofuran at a mass ratio of 1:1. Pour the tetrahydrofuran solution into a beaker containing the PVC granules and stir it at 100r / min using a cantilever stirrer. After all the PVC granules have dissolved, dispersion one is obtained.

[0094] The uniformly distributed AlN mixed powder obtained above was slowly added to dispersion one, and stirred at 100 r / min for 2 h using a cantilever stirrer to avoid particle agglomeration, thus obtaining dispersion two.

[0095] Pour the prepared dispersion into The AlN / PVC composite thermal pad is obtained by placing the solution in a silicone mold at room temperature and allowing it to solidify naturally.

[0096] The thermal conductivity, resistivity, and hardness of the thermal pad were tested, and the results were as follows: thermal conductivity was 8.47 W / (m·K) and Shore hardness was 107. Its thermal conductivity was 12.9% higher than that of the thermal pad currently using dimethyl silicone oil as a carrier (7.5 W / (m·K)). However, the results were still worse than those of Example 1.

[0097] Comparative Example 2

[0098] The process of Example 1 was repeated, except that different filler particle sizes were used: 15μm spherical AlN powder, 10μm spherical AlN powder, 5μm spherical AlN powder, and 2μm spherical AlN powder were weighed in a mass ratio of 1:2:3:4, with masses of 20.00g, 40.00g, 60.00g, and 80.00g respectively. These powders were placed in a zirconia ball mill jar, and 600g of zirconia grinding balls with a diameter of 5mm were added. Before ball milling, the jar was sealed with an O-ring, evacuated, and filled with argon gas. The ball milling was carried out at a speed of 150r / min, with a start / stop interval of 30min, for a total of 3h, to obtain AlN mixed powder with uniform particle size distribution.

[0099] Weigh out PVC granules (25.00g), plasticizer DBP (50.00g), and tetrahydrofuran (25.00g) in a mass ratio of 1:2:1. Pour the tetrahydrofuran solution into a beaker containing PVC granules and stir it at 100r / min using a cantilever stirrer. After the PVC granules are completely dissolved, add the plasticizer dropwise and stir for 3 hours to obtain dispersion one.

[0100] The uniformly distributed AlN mixed powder obtained above was slowly added to dispersion one, and stirred at 100 r / min for 2 h using a cantilever stirrer to avoid particle agglomeration, thus obtaining dispersion two.

[0101] Pour the prepared dispersion into The AlN / PVC composite thermal pad is obtained by placing the solution in a silicone mold at room temperature and allowing it to solidify naturally.

[0102] The thermal conductivity, resistivity, and hardness of the thermal pad were tested, and the results were as follows: thermal conductivity was 9.13 W / (m·K) and Shore hardness was 59. Its thermal conductivity was 21.7% higher than that of the thermal pad currently using dimethyl silicone oil as a carrier (7.5 W / (m·K)). However, the results were still worse than those of Example 1.

[0103] Comparative Example 3

[0104] Weigh out 1μm spherical AlN powder, 0.5μm spherical AlN powder, and 0.1μm spherical AlN powder at a mass ratio of 2:3:5, with masses of 40.00g, 60.00g, and 100.00g respectively. Place them in a zirconia ball mill jar, add 600g of zirconia grinding balls with a diameter of 5mm, seal the jar with an O-ring before ball milling, evacuate the jar and fill it with argon gas, and ball mill at a speed of 150r / min with a start / stop interval of 30min for a total of 3h to obtain AlN mixed powder with uniform particle size distribution.

[0105] The dispersion was prepared according to the method described in Example 1.

[0106] The uniformly distributed AlN mixed powder obtained in Example 3 was slowly added to Dispersion 1, and stirred at 100 r / min for 3 h using a cantilever stirrer to avoid particle agglomeration, thus obtaining Dispersion 2.

[0107] Pour the prepared dispersion into The AlN / PVC composite thermal pad is obtained by placing the solution in a silicone mold at room temperature and allowing it to solidify naturally.

[0108] The thermal conductivity, resistivity, and hardness of the thermal pad were tested, and the results were as follows: the thermal conductivity was 8.63 W / (m·K) and the Shore hardness was 47. Its thermal conductivity is 15.1% higher than that of the thermal pads currently using dimethyl silicone oil as a carrier (7.5 W / (m·K)).

[0109] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A PVC composite thermally conductive pad, comprising PVC material, organic solvent, plasticizer, and filler; based on 100 wt% of the thermally conductive pad, the PVC material, organic solvent, and plasticizer together account for 20-60 wt%, and the filler accounts for 40-80 wt%; based on 100 wt% of the total amount of the PVC material, organic solvent, and plasticizer, the PVC material accounts for 15-50 wt%, the organic solvent accounts for 5-40 wt%, and the plasticizer accounts for 30-65 wt%; the filler is a spherical powder with various particle sizes, the various particle sizes including four selected from 8-12 μm, 4-7 μm, 2-3 μm, 0.8-1.5 μm, 0.4-0.7 μm, 0.2 μm, and 0.1 μm; the filler is selected from one or more of aluminum nitride, boron nitride, alumina ceramic particles, silicon nitride, and silicon carbide.

2. The PVC composite thermally conductive pad according to claim 1, characterized in that, The molecular weight of the PVC material is 20,000 to 200,000; and / or, The organic solvent is selected from at least one of tetrahydrofuran, cyclohexanone, dichloroethane, tetrahydropyran, chloroform, carbon tetrachloride, and xylene; and / or, The plasticizer is selected from at least one of diisooctyl sebacate, dibutyl phthalate, dioctyl phthalate, 2-nitrophenyl octyl ether, (2-ethylhexyl) phthalate, and diethyl phthalate.

3. The PVC composite thermally conductive pad according to claim 1, characterized in that, The molecular weight of the PVC material is 50,000 to 120,000.

4. The PVC composite thermally conductive pad according to claim 1, characterized in that, The different particle sizes include four types selected from 4~7μm, 2~3μm, 0.8~1.5μm, 0.4~0.7μm, 0.2μm and 0.1μm.

5. The PVC composite thermally conductive pad according to claim 1, characterized in that, The proportions of the four different particle sizes, from largest to smallest, are 5~10wt%, 15~25wt%, 25~40wt%, and 30~55wt%, respectively.

6. The PVC composite thermally conductive pad according to any one of claims 1 to 5, characterized in that, Based on 100wt% of the thermally conductive pad, the PVC material, the organic solvent, and the plasticizer account for 30-50wt%, and the filler accounts for 50-70wt%.

7. The PVC composite thermally conductive pad according to claim 6, characterized in that, Based on a total of 100wt% of the PVC material, the organic solvent, and the plasticizer, the PVC material accounts for 20-40wt%, the organic solvent accounts for 10-30wt%, and the plasticizer accounts for 40-60wt%.

8. A method for preparing a PVC composite thermally conductive pad, used to prepare the PVC composite thermally conductive pad according to any one of claims 1 to 7, the method comprising: (1) The PVC material, the organic solvent, and the plasticizer are mixed to form a dispersion. (2) Add the uniformly mixed filler to the first dispersion and stir to obtain the second dispersion; (3) Perform molding treatment on the second dispersion to obtain the PVC composite thermal conductive pad; based on 100wt% of the PVC material, the organic solvent, the plasticizer and the filler, the total of the PVC material, the organic solvent and the plasticizer accounts for 20~60wt% and the filler accounts for 40~80wt%; based on 100wt% of the total amount of the PVC material, the organic solvent and the plasticizer, the PVC material accounts for 15~50wt%, the organic solvent accounts for 5~40wt% and the plasticizer accounts for 30~65wt%; the filler is a spherical powder with a variety of different particle sizes, the different particle sizes include four of the following: 8~12μm, 4~7μm, 2~3μm, 0.8~1.5μm, 0.4~0.7μm, 0.2μm and 0.1μm.

9. The preparation method according to claim 8, characterized in that, In step (1), the PVC material is first mixed with the organic solvent and stirred, then the plasticizer is added and stirred to obtain the dispersion; and / or, In step (2), the uniformly mixed filler is mixed by ball milling; and / or, The molding process is carried out in a mold to obtain the thermally conductive pad.

10. The preparation method according to claim 8, characterized in that, The uniformly mixed packing material in step (2) is obtained as follows: various packing materials of different particle sizes are placed in a ball mill jar filled with protective gas and ball-milled to obtain the uniformly mixed packing material; and / or, The molding process involves pressing or static molding in a mold to obtain the thermally conductive pad.

11. The preparation method according to any one of claims 8 to 10, characterized in that, Based on 100 wt% of the PVC material, the organic solvent, the plasticizer, and the filler, the PVC material, the organic solvent, and the plasticizer together account for 30-50 wt%, and the filler accounts for 50-70 wt%. And / or, Based on a total usage of 100wt% for the PVC material, the organic solvent, and the plasticizer, the PVC material accounts for 20-40wt%, the organic solvent accounts for 10-30wt%, and the plasticizer accounts for 40-60wt%.

12. A PVC composite thermally conductive pad obtained by the preparation method according to any one of claims 8 to 11.

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