High-toughness thermally conductive polyurethane-based composite material and preparation method thereof

Abstract

The present disclosure provides a high-toughness heat-conductive polyurethane-based composite material, mainly including 15-45% isocyanate prepolymer, 5-20% polyester polyol B, 40-75% thermal conductive filler, 1-5% chain extender, and the isocyanate index of the composite material is finally 0.98-1.03. The tensile strength of the high-toughness heat-conductive polyurethane-based composite material prepared by the present disclosure is 9.5-11MPa, the elongation at break is 125-160%, the thermal conductivity is 0.8-1.0W / (m·K), the bonding strength is 7-9MPa, and the elastic modulus is 30-50MPa. On the basis of meeting the requirements of thermal conductivity and bonding strength, higher tensile strength and better elastic elongation are provided, which improves the problem that traditional polyurethane heat-conductive composite materials can only ensure heat conduction and bonding without taking into account strength and toughness at the same time. The preparation method provided by the present disclosure is simple, the preparation process is simple, and other additives and any organic solvents are not added, and it is particularly suitable for the bonding of power battery PACK bags.

Description

Technical Field

[0001] The present disclosure relates to the technical field of polyurethane-based heat dissipation materials, and in particular to a high-toughness thermally conductive polyurethane-based composite material and a preparation method thereof. Background Art

[0002] The core energy supply component of new energy vehicles is a power battery pack composed of thousands of power cells connected in series and parallel. During operation, the power density is high and the heat generated is enormous. Therefore, solving the heat dissipation problem of the power battery pack is a key to maintaining the life of the power battery.

[0003] In recent years, due to the trend of lightweight and long driving range of electric vehicles, the power batteries of automobiles have gradually shifted to CTP structures. Battery packs with this CTP structure generally require a large amount of adhesives to connect and fix the battery cells instead of traditional mechanical connection methods. Therefore, the thermal interface material used in the CTP structure of the power battery needs to, on the one hand, promptly conduct the heat generated by the battery cells during operation to the external heat dissipation components to achieve the function of thermal management. On the other hand, it also needs to play the role of reliably connecting and fixing the battery cells to the external PACK shell. Since the car vibrates for a long time during use, the thermal interface material needs to have both heat dissipation and good toughness to play a buffering and protective role for the battery. The currently commonly used polyurethane-based thermal interface materials, although they have high bonding strength and tensile strength, have low elongation at break, that is, low toughness. Therefore, a high-toughness thermally conductive polyurethane-based composite material with both high toughness and high strength is needed to meet the working conditions of long-term high-frequency vibration of automobile power batteries. Summary of the Invention

[0004] In order to at least partially solve the technical problems raised above, the present disclosure provides a high-toughness thermally conductive polyurethane-based composite material and a preparation method thereof.

[0005] One aspect of the present disclosure provides a high-toughness thermally conductive polyurethane-based composite material, which comprises, based on the mass percentage of the high-toughness thermally conductive polyurethane-based composite material, 15% to 45% of isocyanate prepolymer, 5% to 20% of polyester polyol B, 1% to 5% of chain extender, and 40% to 75% of thermally conductive filler.

[0006] According to an embodiment of the present disclosure, based on the mass percentage of the high-toughness thermally conductive polyurethane-based composite material, the isocyanate prepolymer includes: 5% to 20% of polyester polyol A, and 10% to 25% of isocyanate.

[0007] According to an embodiment of the present disclosure, the number average molecular weight of polyester polyol A is 500-1000; the number average molecular weight of polyester polyol B is 2000-3000.

[0008] According to an embodiment of the present disclosure, the isocyanate index of the isocyanate prepolymer is 5-6.5.

[0009] According to an embodiment of the present disclosure, the isocyanate index of the high-toughness thermally conductive polyurethane-based composite material is 0.98-1.03.

[0010] Specifically, the isocyanate index is the molar ratio of isocyanate groups to hydroxyl groups in a material or mixture.

[0011] According to an embodiment of the present disclosure, polyester polyol A and polyester polyol B both include at least one of polycaprolactone polyol, polybutylene adipate diol, polyethylene adipate-propylene glycol diol, polycarbonate diol, polycastor oil adipate polyol, and refined castor oil polyol; the functionality of polyester polyol A and polyester polyol B are both 2-4;

[0012] According to an embodiment of the present disclosure, the isocyanate includes one or more of toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, or polymethylene polyphenyl isocyanate.

[0013] According to an embodiment of the present disclosure, the chain extender includes at least one of ethylene glycol, 1,3-propylene glycol, glycerol, butylene glycol, 1,4-butylene glycol, dipropylene glycol, neopentyl glycol, hexylene glycol, or diethylene glycol.

[0014] According to an embodiment of the present disclosure, the thermally conductive filler includes: at least one of surface-modified α-alumina, magnesium oxide, zinc oxide, boron nitride, and aluminum nitride; wherein the particle size of the thermally conductive filler is 1-50 μm; and the free water content of the powder of the thermally conductive filler is ≤0.2.

[0015] Another aspect of the present disclosure provides a method for preparing a high-toughness thermally conductive polyurethane-based composite material, comprising: mixing polyester polyol A and isocyanate to obtain an isocyanate prepolymer; adding a thermally conductive filler to the isocyanate prepolymer to remove bubbles to obtain a mixture A; adding a chain extender and polyester polyol B to the mixture A and mixing to obtain a mixture B; pouring the mixture B into a mold and curing it to obtain a high-toughness thermally conductive polyurethane-based composite material.

[0016] According to an embodiment of the present disclosure, the mixing of polyester polyol A and isocyanate includes: controlling the mass percentages of polyester polyol A and isocyanate so that the isocyanate index of the isocyanate prepolymer is within a preset range of 5-6.5.

[0017] According to the embodiment of the present disclosure, the mass percentages of the mixture A, the chain extender and the polyester polyol B are controlled so that the isocyanate index of the high-toughness thermally conductive polyurethane-based composite material is within the preset range of 0.98-1.03.

[0018] The present disclosure has at least the following beneficial effects:

[0019] (1) Additives and organic solvents are toxic, harmful and have a bad odor. Excessive use will make degradation difficult and cause environmental pollution. The present invention does not use any other additives and organic solvents except chain extenders, which is low-carbon and environmentally friendly.

[0020] (2) The present disclosure adopts a method of introducing polyester polyols of different molecular weights in steps, and synthesizes a prepolymer with low molecular weight polyester polyol A and isocyanate, which can reduce the viscosity of the prepolymer and avoid the occurrence of excessive viscosity during the preparation process, which makes it difficult to remove the introduced bubbles. It is supplemented with high molecular weight polyester polyol B to ensure that the system can form a moderately cross-linked network structure during the curing process. The combination of the two is beneficial to enhancing the cohesion of the matrix, increasing the density of intermolecular hydrogen bonds while ensuring the strength of the material, and increasing energy dissipation, thereby improving the toughness of the material.

[0021] (3) The present invention prepares the isocyanate-terminated prepolymer by regulating the molar ratio of the raw materials, adjusts the chemical crosslinking density of the matrix material, and at the same time, allows some hydroxyl groups and isocyanate groups in the system to release heat when synthesizing the prepolymer, avoiding the generation of excessive bubbles inside the material due to large amounts of heat release during the curing process, thereby affecting the material properties and ensuring the processing performance of the material to the greatest extent.

[0022] (4) The present invention improves the bonding strength between the material and the bonded material by controlling a specific isocyanate index range, and cooperates with multiple components at specific contents, thereby achieving a thermally conductive composite material having basic properties such as high thermal conductivity, high adhesion, and high strength, while also having high toughness and low elastic modulus. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram shows a block diagram of raw materials included in a high-toughness thermally conductive polyurethane-based composite material according to an embodiment of the present disclosure.

[0024] Figure 2 The flowchart of the preparation method of the high-toughness thermally conductive polyurethane-based composite material according to an embodiment of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0026] However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known technologies are omitted to avoid unnecessarily confusing the concepts of the present disclosure.

[0027] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The term "comprising" used herein indicates the presence of features, steps, operations, but does not exclude the presence or addition of one or more other features.

[0028] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0029] Figure 1 A schematic diagram shows a block diagram of raw materials included in a high-toughness thermally conductive polyurethane-based composite material according to an embodiment of the present disclosure.

[0030] Understandably, Figure 1 The block diagram shown is only used to reflect the inclusion relationship between the high-toughness thermally conductive polyurethane-based composite material and its raw materials. All raw materials in the high-toughness thermally conductive polyurethane-based composite material have been mixed evenly.

[0031] In some embodiments of the present disclosure, Figure 1 As shown, the high-toughness thermally conductive polyurethane-based composite material includes: in the high-toughness thermally conductive polyurethane-based composite material, by mass percentage, 15-45% of isocyanate prepolymer, 5-20% of polyester polyol B, 1-5% of chain extender, and 40-75% of thermal conductive filler.

[0032] In some embodiments of the present disclosure, Figure 1 As shown, in the high-toughness thermally conductive polyurethane-based composite material, the isocyanate prepolymer includes: 5-20% polyester polyol A and 10-25% isocyanate, calculated by mass percentage.

[0033] In some embodiments of the present disclosure, the number average molecular weight of polyester polyol A is 500-1000; the number average molecular weight of polyester polyol B is 2000-3000.

[0034] In some embodiments of the present disclosure, the isocyanate prepolymer has an isocyanate index of 5-6.5.

[0035] In some embodiments of the present disclosure, the isocyanate index of the high-toughness thermally conductive polyurethane-based composite material is 0.98-1.03.

[0036] In some embodiments of the present disclosure, the isocyanate index is the molar ratio of isocyanate groups to hydroxyl groups in a material or mixture, wherein the isocyanate groups are derived from isocyanate and the hydroxyl groups are derived from polyester polyol A, polyester polyol B, and the chain extender.

[0037] In some embodiments of the present disclosure, polyester polyol A and polyester polyol B are one or more of polycaprolactone polyol, polybutylene adipate diol, polyethylene adipate-propylene glycol diol, polycarbonate diol, polycastor oil adipate polyol, and refined castor oil polyol; the functionality of polyester polyol A and polyester polyol B is 2-4;

[0038] In some embodiments of the present disclosure, the isocyanate is one or more of toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, or polymethylene polyphenyl isocyanate.

[0039] In some embodiments of the present disclosure, the thermally conductive filler is one or more of surface-modified α-alumina, magnesium oxide, zinc oxide, boron nitride, and aluminum nitride; the particle size of the thermally conductive filler is 1-50 μm; and the free water content of the thermally conductive filler powder is ≤0.2.

[0040] In some embodiments of the present disclosure, the chain extender is one or more of ethylene glycol, 1,3-propylene glycol, glycerol, butylene glycol, 1,4-butylene glycol, dipropylene glycol, neopentyl glycol, hexylene glycol, or diethylene glycol.

[0041] Figure 2 The flowchart of the preparation method of the high-toughness thermally conductive polyurethane-based composite material according to an embodiment of the present disclosure is schematically shown.

[0042] like Figure 2 As shown, the present disclosure also provides a method for preparing a high-toughness thermally conductive polyurethane-based composite material for preparing the high-toughness thermally conductive polyurethane-based composite material as described above, comprising:

[0043] S1, mixing polyester polyol A and isocyanate to obtain an isocyanate prepolymer;

[0044] S2, adding a thermally conductive filler to the isocyanate prepolymer to remove bubbles, thereby obtaining a mixture A;

[0045] S3, adding a chain extender and polyester polyol B to the mixture A and mixing to obtain a mixture B;

[0046] S4, pouring the mixture B into a mold at room temperature and curing it to obtain a high-toughness thermally conductive polyurethane-based composite material.

[0047] In some embodiments of the present disclosure, the mixing reaction of polyester polyol A and isocyanate includes: controlling the mass percentages of polyester polyol A and isocyanate so that the isocyanate index of the isocyanate prepolymer is within a preset range of 5-6.5.

[0048] In some embodiments of the present disclosure, adding a chain extender and polyester polyol B to the mixture A includes: controlling the mass percentages of the mixture A, the chain extender and the polyester polyol B so that the isocyanate index of the high-toughness thermally conductive polyurethane-based composite material is within a preset range of 0.98-1.03.

[0049] In some embodiments of the present disclosure, polyester polyol A and polyester polyol B are both subjected to a high-temperature vacuum dehydration operation before use. Specifically, the polyester polyol is vacuumed to below -0.09 MPa for dehydration for 2-3 hours under stirring at 110-130°C, and then cooled to room temperature to obtain a dehydrated polyester polyol, wherein the free water content in the dehydrated polyester polyol is less than or equal to 0.2%.

[0050] In some embodiments of the present disclosure, the mixing reaction of polyester polyol A and isocyanate specifically includes: adding polyester polyol A to isocyanate, heating to 75-85° C., evacuating to below -0.09 MPa, and reacting for 2-3 hours.

[0051] In some embodiments of the present disclosure, the precondition for removing bubbles when adding the thermally conductive filler to the isocyanate prepolymer is a vacuum condition, and the time for removing bubbles is 3-6 hours.

[0052] In some embodiments of the present disclosure, during the process of pouring the mixture B into a mold and curing it to obtain a high-toughness thermally conductive polyurethane-based composite material, the mold temperature and the ambient temperature are room temperature, and the curing time is 7 days.

[0053] In some embodiments of the present disclosure, the chain extender is preliminarily dehydrated under vacuum conditions at 100-120°C.

[0054] In some embodiments of the present disclosure, the particle size of the thermal conductive filler is 1-50 μm, and the thermal conductive filler is pre-dehydrated and dried at 120-150° C. The free water content of the thermal conductive filler powder after dehydration is less than or equal to 0.2.

[0055] The technical solution of the present disclosure is further illustrated below through specific embodiments.

[0056] Example 1

[0057] 9.5 parts by weight of polycaprolactone polyol A was weighed and added to 17 parts by weight of polymethylene polyphenyl isocyanate to obtain an isocyanate prepolymer.

[0058] 60 parts by weight of aluminum oxide was added to the isocyanate prepolymer to remove bubbles, thereby obtaining a mixture A;

[0059] 3.5 parts by weight of a chain extender 1,4-butanediol and 10 parts by weight of polycaprolactone polyol B were added to mixture A to obtain a mixture B;

[0060] The mixture B is poured into a mold and solidified to obtain a high-toughness thermally conductive polyurethane-based composite material.

[0061] Example 2

[0062] The difference between Example 2 and Example 1 is that, in this embodiment,

[0063] The molecular weight of polycaprolactone polyol A is 500;

[0064] The weight portion of polycaprolactone polyol A is 16;

[0065] The weight parts of polymethylene polyphenyl isocyanate is 18;

[0066] Everything else remains unchanged.

[0067] Example 3

[0068] The difference between Example 3 and Example 1 is that, in this embodiment,

[0069] The weight portion of polycaprolactone polyol A is 12;

[0070] The weight parts of polymethylene polyphenyl isocyanate is 16;

[0071] The weight percentage of thermally conductive filler is 62;

[0072] The weight portion of chain extender 1,4-butanediol is 4;

[0073] The weight portion of polycaprolactone polyol B is 8.5;

[0074] Everything else remains unchanged.

[0075] In Examples 1 to 3, the isocyanate index of the isocyanate prepolymer is in the range of 5-5.6, and the isocyanate index of the finally generated high-toughness thermally conductive polyurethane-based composite material is in the range of 0.98-1.03.

[0076] In order to better understand the technical solutions and technical effects of the present disclosure, the present disclosure also provides comparative examples 1 to 3.

[0077] Comparative Example 1

[0078] The difference between Comparative Example 1 and Example 1 is that, in this comparative example,

[0079] The weight portion of polycaprolactone polyol A is 20;

[0080] In the process of converting mixture A to mixture B, only the chain extender is added, and polycaprolactone polyol B is not added.

[0081] Everything else remains unchanged.

[0082] Comparative Example 2

[0083] The difference between Comparative Example 2 and Example 2 is that, in this comparative example,

[0084] The weight portion of polycaprolactone polyol A is 9.5;

[0085] The weight portion of polymethylene polyphenyl isocyanate is 15;

[0086] The weight portion of chain extender 1,4-butanediol is 3.2;

[0087] The weight portion of polycaprolactone polyol B is 8;

[0088] Everything else remains unchanged.

[0089] In Comparative Example 2, the isocyanate index of the formed isocyanate prepolymer was 6.6.

[0090] Comparative Example 3

[0091] The difference between Comparative Example 3 and Example 3 is that, in this comparative example,

[0092] The weight portion of polycaprolactone polyol A is 10.5;

[0093] The weight portion of chain extender 1,4-butanediol is 3 parts;

[0094] Everything else remains unchanged.

[0095] In Comparative Example 3, the isocyanate index of the formed polyurethane-based composite material was 1.08.

[0096] The relevant performance data of Examples 1-3 and Comparative Examples 1-3 are shown in the following table.

[0097] Table 1 Performance index data of Examples 1-3 and Comparative Examples 1-3

[0098]

[0099] It can be seen from the above table that Example 1, Example 2 and Example 3 have high thermal conductivity, high adhesion, high tensile strength, high toughness and low elastic modulus.

[0100] Compared with Example 1, in Comparative Example 1, polyester polyols of the same molecular weight were added at one time, the system viscosity in the mixture was higher, and the chemical crosslinking density was too high during the curing process, resulting in a significant decrease in the material's tensile strength, elongation at break, and bonding strength to the aluminum substrate.

[0101] Compared with Example 2, in Comparative Example 2, when the isocyanate prepolymer was prepared, the isocyanate index of the isocyanate prepolymer was 6.6, and the tensile strength, elongation at break and bonding strength to the aluminum substrate were significantly reduced.

[0102] Compared with Example 3, in Comparative Example 3, the isocyanate index of the polyurethane composite material is 1.08, the tensile strength, elongation at break and the bonding strength to the aluminum substrate are significantly reduced, and the thermal conductivity is lower.

[0103] The more active sites there are in the matrix material (other materials except the thermally conductive filler), the greater the crosslinking density per unit volume in the matrix material, which is manifested macroscopically as the mechanical properties of the composite material. The present invention controls the isocyanate index of the isocyanate prepolymer and the isocyanate index of the final product within the specific range described above by step-by-step introduction of polyester polyols of different molecular weights and controlling the weight of the chain extender. The specific isocyanate index, that is, the specific molar ratio of isocyanate groups to hydroxyl groups, can provide appropriate active sites, and the matrix material (other materials except the thermally conductive filler) can form appropriate crosslinks, so that the mechanical properties of the composite material can be maintained within an appropriate range.

[0104] In the embodiments and comparative examples of the present disclosure, the performance testing method is as follows:

[0105] Thermal conductivity: Refer to ASTM D5470 and use a steady-state heat flow method thermal conductivity tester to measure.

[0106] Tensile shear strength: With reference to the standard GB / T 7124-2008 "Determination of tensile shear strength of adhesives (rigid material to rigid material)", the test was carried out using a universal material testing machine. The test was conducted on two aluminum sheets of 100 (±0.25) mm × 25 (±0.25) mm × 1.5 (±0.1) mm, with an overlap of 25 × 12.5 mm and copper wire fixed to an overlap thickness of 0.2 mm.

[0107] Tensile strength, elongation at break, elastic modulus, and toughness: Refer to standard GB / T 528-2009 "Rubber, vulcanized or thermoplastic — Determination of tensile stress-strain properties." Universal material testing machine is used for testing. Composite material samples are cut into dumbbell-shaped samples for performance testing.

[0108] Hardness: Refer to the standard GB / T 531.1-2008 "Rubber, vulcanized or thermoplastic - Test method for indentation hardness - Part 1: Shore durometer method (Shore hardness)", and use Shore durometer for testing.

[0109] Density: Tested in accordance with GB / T 533-2008 “Rubber, vulcanized or thermoplastic — Determination of density”.

[0110] The embodiments of the present disclosure have been described in detail. It should be noted that any implementations not depicted or described in the drawings or the main text of the specification are known to those skilled in the art and are not described in detail. Furthermore, the definitions of the materials described above are not limited to the specific chemical or physical materials mentioned in the embodiments, and can be easily modified or replaced by those skilled in the art.

[0111] Those skilled in the art will appreciate that the features described in the various embodiments and / or claims of this disclosure may be combined and / or coupled in various ways, even if such combinations and / or couplings are not explicitly described in this disclosure. In particular, the features described in the various embodiments and / or claims of this disclosure may be combined and / or coupled in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or couplings are intended to fall within the scope of this disclosure.

[0112] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above are only specific embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the scope of protection of the present disclosure.

Claims

1. A high-toughness thermally conductive polyurethane-based composite material, characterized in that: Based on the mass percentage of the high-toughness thermally conductive polyurethane-based composite material, its raw materials include: 15% to 45% of isocyanate prepolymer, 5% to 20% of polyester polyol B, 1% to 5% of chain extender, and 40% to 75% of thermally conductive filler; The isocyanate index of the isocyanate prepolymer is in the range of 5-6.5, and the isocyanate index of the high-toughness thermally conductive polyurethane-based composite material is in the range of 0.98-1.

03.

2. The high-toughness thermally conductive polyurethane-based composite material according to claim 1, characterized in that: Based on the mass percentage of the high-toughness thermally conductive polyurethane-based composite material, the raw materials of the isocyanate prepolymer include: 5% to 20% of polyester polyol A and 10% to 25% of isocyanate.

3. The high-toughness thermally conductive polyurethane-based composite material according to claim 2, characterized in that: The number average molecular weight of the polyester polyol A is 500-1000; The number average molecular weight of the polyester polyol B is 2000-3000.

4. The high-toughness thermally conductive polyurethane-based composite material according to claim 2, characterized in that: The polyester polyol A and the polyester polyol B both include at least one of polycaprolactone polyol, polybutylene adipate diol, polyethylene adipate-propylene glycol diol, polycarbonate diol, polycastor oil adipate polyol, and refined castor oil polyol; The functionality of the polyester polyol A and the polyester polyol B are both 2-4.

5. The high-toughness thermally conductive polyurethane-based composite material according to claim 1, characterized in that: The isocyanate includes at least one of toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate or polymethylene polyphenyl isocyanate.

6. The high-toughness thermally conductive polyurethane-based composite material according to claim 1, characterized in that: The chain extender includes at least one of ethylene glycol, 1,3-propylene glycol, glycerol, butylene glycol, dipropylene glycol, neopentyl glycol, hexylene glycol or diethylene glycol.

7. The high-toughness thermally conductive polyurethane-based composite material according to claim 1, characterized in that: The thermally conductive filler comprises: at least one of surface-modified α-alumina, magnesium oxide, zinc oxide, boron nitride, and aluminum nitride; The particle size of the thermal conductive filler is 1-50 μm; The free water content of the powder of the thermal conductive filler is ≤0.

2.

8. A method for preparing the high-toughness thermally conductive polyurethane-based composite material according to any one of claims 1 to 7, characterized in that: include: The polyester polyol A and the isocyanate are mixed and reacted to obtain an isocyanate prepolymer; adding a thermally conductive filler into the isocyanate prepolymer to remove air bubbles, thereby obtaining a mixture A; Adding a chain extender and polyester polyol B to the mixture A to obtain a mixture B; The mixture B is poured into a mold and solidified to obtain the high-toughness thermally conductive polyurethane-based composite material.

9. The method for preparing the high-toughness thermally conductive polyurethane-based composite material according to claim 8, characterized in that: The mixing of polyester polyol A and isocyanate comprises: The mass percentages of the polyester polyol A and the isocyanate are controlled so that the isocyanate index of the isocyanate prepolymer is within a preset range of 5-6.

5.

10. The method for preparing the high-toughness thermally conductive polyurethane-based composite material according to claim 8, characterized in that: The adding of chain extender and polyester polyol B into the mixture A comprises: The mass percentages of the mixture A, the chain extender and the polyester polyol B are controlled so that the isocyanate index of the high-toughness thermally conductive polyurethane-based composite material is within a preset range of 0.98-1.03.

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