High-heat-conductivity self-repairing heat-conducting composite material and preparation method thereof

Abstract

The invention relates to the field of preparation of heat-conducting composite materials, in particular to a flexible thermal interface composite material and a preparation method thereof. The problems of insufficient heat dissipation efficiency and insufficient service life of equipment in the prior art are solved. Comprising a polysiloxane polymer, boric acid and a modified boron nitride filler. The material is endowed with excellent heat-conducting property and mechanical property, so that the elastomer composite material has higher heat-conducting property and excellent interface thermal resistance. The composite material synthesized by the invention is balanced between the heat-conducting property and the self-repairing property, the excellent heat-conducting property and the self-repairing property of the material simplify the multi-layer structure of a flexible electronic device, and the stability is provided for long-term use of the flexible electronic device.

Description

Technical Field

[0001] The invention relates to the field of preparation of thermally conductive composite materials, in particular to a flexible thermal interface composite material and a preparation method thereof. Background Art

[0002] Thermal Interface Materials (TIMs) are currently widely used in electronic equipment, LEDs, optoelectronic devices and other fields. They can effectively improve thermal conductivity and reduce the failure and life problems of electronic and electrical equipment caused by excessive temperature. However, this field contains huge opportunities in the development process, but also faces many difficulties.

[0003] Electronic devices have become an indispensable part of modern life, permeating all aspects of people's daily activities and industrial activities, from smartphones and laptops to complex electronic systems for aerospace and automotive applications. With the pursuit of miniaturization and high performance of electronic devices, the heat generated during the operation of electronic devices cannot be dissipated in time. Major challenges.

[0004] Excessive heat accumulation not only affects the performance and reliability of electronic components, but also poses safety risks and limits further technological advancement. Effective thermal management is essential to address these challenges and release the power of electronic devices. Traditionally, metal heat sinks and fans dissipate heat from electronic components through conduction and convection mechanisms. While these methods are relatively effective for traditional electronic systems, they have limitations in handling the escalating heat flux density and electronic components caused by miniaturization and densification.

[0005] Therefore, there is an urgent need to propose a high thermal conductivity self-repairing thermally conductive composite material and a preparation method to solve the above technical problems. Summary of the invention

[0006] In order to solve the problems of insufficient heat dissipation efficiency and equipment life formed by conventional technologies, the present invention provides a brief overview of the present invention below to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to determine the key or important parts of the present invention, nor is it intended to limit the scope of the present invention.

[0007] The technical solution of the present invention:

[0008] A high thermal conductivity self-repairing thermal conductive composite material, the high thermal conductivity self-repairing thermal conductive composite material is composed of polysiloxane, boric acid, and modified boron nitride filler;

[0009] The mass fraction of the polysiloxane polymer is 40-60 parts, the mass fraction of boric acid is 0.1-0.5 parts, and the mass fraction of the modified boron nitride filler is 40-60 parts.

[0010] Preferably, the polysiloxane polymer is one or more of silanol-terminated polydimethylsiloxane and alkanehydroxy-terminated polydimethylsiloxane.

[0011] Preferably, the viscosity of the polysiloxane polymer is one or more of 1000, 1500, 3000, and 4000 cp·s.

[0012] A method for preparing a high thermal conductivity self-repairing thermally conductive composite material comprises the following steps: weighing a polysiloxane polymer, adding tetrahydrofuran to dissolve and mix the mixture evenly, adding a boric acid solution fully dissolved in an ethanol reagent to the mixture, heating the mixture and stirring the mixture evenly, adding a modified boron nitride filler, stirring the mixture evenly at a constant temperature, and obtaining a viscous polymer solution.

[0013] Preferably, after adding the boric acid solution, the temperature is raised to 60° C. and stirring is started, and the constant temperature stirring time is 0.5-1 h.

[0014] A method for preparing a modified boron nitride filler comprises the following steps: weighing a boron nitride filler, adding 3-6 times the mass fraction of a modifier, mixing evenly, dissolving the filler in deionized water, placing the filler in a closed ball mill for ball milling, washing the filler with deionized water for multiple times, and drying the filler at 80° C. to obtain the modified boron nitride filler.

[0015] Preferably, the particle size of the boron nitride filler is one or more of 50 μm, 40 μm, 30 μm, 20 μm, 10 μm, 5 μm, and 2 μm.

[0016] Preferably, the material of the ball mill is one of zirconium oxide, stainless steel, nylon and agate.

[0017] Preferably: the ball mill speed is 500 rad / min, and the ball milling time is 12 h

[0018] The present invention has the following beneficial effects:

[0019] The present invention endows the material with excellent thermal conductivity and mechanical properties, so that the elastomer composite material has higher thermal conductivity and excellent interface thermal resistance;

[0020] The composite material synthesized by the present invention achieves a balance between thermal conductivity and self-healing performance. The excellent thermal conductivity and self-healing performance of the material simplifies the multilayer structure of the flexible electronic device and provides stability for its long-term use. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described below by specific embodiments. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0022] Specific implementation method 1: A high thermal conductivity self-repairing thermal conductive composite material in this implementation method, wherein the high thermal conductivity self-repairing thermal conductive composite material is composed of a polysiloxane polymer, boric acid, and a modified boron nitride filler;

[0023] The mass fraction of the polysiloxane polymer is 40-60 parts, the mass fraction of boric acid is 0.1-0.5 parts, and the mass fraction of the modified boron nitride filler is 40-60 parts.

[0024] The composition and structure of this highly thermally conductive self-healing thermally conductive composite material can effectively solve the limitations of traditional heat dissipation materials, especially in dealing with the heat dissipation problems of high heat flux density and miniaturized and dense electronic devices.

[0025] Specific implementation method 2: In this implementation method, a high thermal conductivity self-repairing thermally conductive composite material is provided, wherein the polysiloxane polymer is one or more of silanol-terminated polydimethylsiloxane and alkanehydroxy-terminated polydimethylsiloxane.

[0026] By selecting one or more of silanol-terminated polydimethylsiloxane and alkanoyl-terminated polydimethylsiloxane as the matrix polymer, the composite material can have good thermal conductivity, mechanical properties and self-healing ability, and meet the high requirements of modern high-performance electronic devices for heat dissipation materials.

[0027] Preferred: The polysiloxane polymer is 107 liquid silicone rubber.

[0028] 107 Liquid silicone rubber in the present invention has excellent elasticity and flexibility, and can adapt to temperature changes and external impacts; self-repairing ability, which can restore its structure and performance when the material is damaged; thermal stability and high temperature resistance, which ensure long-term stable operation under high temperature conditions; electrical insulation, which helps to be used in electronic equipment to avoid electrical failures; good processability, which is easy to mix and mold with fillers to ensure the consistency of material performance.

[0029] Specific implementation method three: In this implementation method, a high thermal conductivity self-repairing thermally conductive composite material is provided, wherein the viscosity of the polysiloxane polymer is one or more of 1000, 1500, 3000, and 4000 cp·s.

[0030] 1000cp·s polysiloxane polymer has good fluidity and can be more easily mixed with other fillers. This helps to obtain uniform distribution of thermal conductive fillers, thereby improving the overall thermal conductivity of the composite material;

[0031] 1500 or 3000cp·s polysiloxane polymers can provide appropriate adhesion while ensuring a certain fluidity, ensuring good bonding between the filler and the matrix. It can optimize the operability of the material and reduce the material stratification phenomenon. It is suitable for applications that require higher viscosity to maintain the shape or reduce flow;

[0032] The higher viscosity of the 40,000cp·s polysiloxane polymer helps provide greater structural stability, especially at higher filler loadings, where it prevents filler settling, making the composite more stable during molding and suitable for materials with complex shapes or that require longer curing times.

[0033] Specific implementation method four: This implementation method is a method for preparing a high thermal conductivity self-healing thermally conductive composite material. Weigh a polysiloxane polymer, add an appropriate amount of tetrahydrofuran to dissolve and mix evenly, add a boric acid solution fully dissolved in an ethanol reagent, stir evenly at 60°C, weigh and add a corresponding number of modified boron nitride fillers, stir at a constant temperature for 0.5-1h, and obtain a viscous polymer solution.

[0034] Through this preparation method, a high thermal conductivity self-healing thermal conductive composite material with excellent thermal conductivity can be obtained; the dispersion of modified boron nitride filler in the polysiloxane matrix not only improves the thermal conductivity of the material, but also enhances its self-healing ability, meeting the application requirements of high-performance materials in thermal management systems.

[0035] Specific implementation method 5: A preparation method of a modified boron nitride filler in this implementation method, weighing a boron nitride filler, adding 3-6 times the mass fraction of a modifier and mixing evenly, dissolving it in deionized water, placing it in a closed ball mill for ball milling, and then washing the filler with deionized water for multiple times, and drying it at 80°C to obtain a modified boron nitride filler.

[0036] Through this preparation method, the boron nitride filler was successfully modified, and its surface properties and dispersibility were improved. The modified boron nitride filler not only has improved dispersibility in the composite material, but also has enhanced bonding with the polymer matrix, providing a basis for the preparation of composite materials with better performance.

[0037] The modification method is a liquid phase assisted ball milling modification method, and the modification auxiliary agent is one or more of urea, sucrose, sulfur, melamine, dry ice, stearylamine, and distilled water.

[0038] Specific implementation method six: In this implementation method, a modified boron nitride filler is prepared, wherein the particle size of the boron nitride filler is one or more of 50 μm, 40 μm, 30 μm, 20 μm, 10 μm, 5 μm, and 2 μm.

[0039] 50μm particle size: This larger particle size is suitable for applications that require less filler and have lower dispersibility requirements. It is often used to enhance the thermal conductivity of materials and is suitable for large sizes and lower requirements for thermal management materials;

[0040] 40μm, 30μm particle size: Boron nitride fillers with moderate particle size can provide a good balance, which can effectively improve thermal conductivity while ensuring a certain dispersion and filler content. They are suitable for medium application scenarios, such as composite materials that require high thermal conductivity and certain mechanical properties;

[0041] 20μm, 10μm particle size: These small and medium-sized boron nitride fillers can effectively improve the thermal conductivity of composite materials and have good dispersibility. They are suitable for composite materials that require high thermal conductivity, good dispersibility and high mechanical properties, especially in the fields of electronic packaging and thermal management;

[0042] 5μm, 2μm particle size: small particle size boron nitride fillers have very good dispersibility and are suitable for applications that require extremely high thermal conductivity and fine structure. These small particle size fillers can be more evenly distributed in composite materials, reduce filler aggregation, and improve the overall thermal conductivity and performance of the material. They are widely used in fields with extremely high requirements for thermal conduction, such as high-end electronic equipment, thermal conductive coatings, etc.

[0043] Mixing large and small particles: can make the filler more evenly distributed in the matrix, while optimizing the thermal conductivity path and improving the overall thermal conductivity of the composite material. Large particle size fillers provide larger heat conduction channels, while small particle size fillers can increase the interface contact area between the filler and the matrix.

[0044] The boron nitride filler can also be in the form of flakes. The flake boron nitride filler can form a "net-like" structure in the composite material, which helps to disperse external impact forces and reduce crack propagation, thereby improving the impact resistance of the material. Moreover, due to its layered structure, it can reduce the friction coefficient of the material surface, reduce friction, and thus improve wear resistance.

[0045] Specific implementation method seven: In the preparation method of a modified boron nitride filler of this implementation method, the material of the ball mill is one of zirconium oxide, stainless steel, nylon, and agate, preferably zirconium oxide.

[0046] Since zirconium oxide has a lower friction coefficient, it can better reduce the heat loss of materials during ball milling, reduce the heat generated by friction, and avoid thermal damage to the sample;

[0047] Zirconia has strong chemical stability in various acid and alkali environments and does not react easily with most chemicals. This makes it widely used in the grinding of some strong acids, strong alkalis and other corrosive substances.

[0048] Specific implementation eight: In the preparation method of a modified boron nitride filler of this implementation, the rotation speed of the ball mill is 500 rad / min, and the ball milling time is 12 hours.

[0049] The efficiency of ball milling is usually closely related to factors such as rotation speed, ball milling time, type and quantity of ball milling media, and hardness of materials. Long-term ball milling helps materials reach finer particle size, but it may also cause over-grinding of some materials, which may lead to too fine particles or changes in morphology. A rotation speed of 500 rad / min and a ball milling time of 12 hours provide sufficient grinding time and energy input.

[0050] Example 1

[0051] Weigh 107 liquid silicone rubber (33 g, 1 mmol) and place it in a 250 ml reaction container, add an appropriate amount of tetrahydrofuran to dissolve and mix evenly, add a solution of boric acid (0.063 g, 1 mmol) fully dissolved in ethanol reagent, stir evenly at 60°C, and mechanically stir at a constant temperature for 0.5-1h to obtain a viscous polymer solution. Place it in an 80°C oven and cure it for 24h to obtain a colorless and transparent sheet material.

[0052] Example 2

[0053] Weigh alkylhydroxyl-terminated polysiloxane (22 g, 1 mmol) and place it in a 250 ml reaction container, add an appropriate amount of tetrahydrofuran to dissolve and mix evenly, add a solution of boric acid (0.063 g, 1 mmol) fully dissolved in ethanol reagent, stir evenly at 60°C, and mechanically stir at a constant temperature for 0.5-1h to obtain a viscous polymer solution, which is placed in an 80°C oven for curing for 24h to obtain a colorless and transparent flaky material.

[0054] Example 3

[0055] Weigh the boron nitride filler in flake form, add 3-6 times the mass fraction of sucrose, mix well, and place in a sealed zirconia ball mill. The ball mill speed is 500 rad / min. After ball milling for 12 hours, wash the filler with deionized water several times and dry at 80°C to obtain a modified boron nitride filler (BN-1);

[0056] Weigh 107 liquid silicone rubber (33 g, 1 mmol) and place it in a 250 ml reaction container, add an appropriate amount of tetrahydrofuran to dissolve and mix evenly, add a solution of boric acid (0.063 g, 1 mmol) fully dissolved in ethanol reagent, stir evenly at 60 ° C to obtain a synthesized polymer solution, weigh and add 30 wt% modified boron nitride filler (14.14 g) to the polymer solution, stir mechanically at a constant temperature for 0.5-1 h to obtain a viscous polymer solution, and place it in an 80 ° C oven for curing for 24 h to obtain the target thermal conductive composite material.

[0057] Example 4

[0058] Weigh the boron nitride filler in flake form, add 3-6 times the mass fraction of urea, mix evenly, dissolve in deionized water, and place in a sealed zirconia ball mill. The ball mill speed is 500 rad / min. After ball milling for 12 hours, wash the filler with deionized water several times, and dry at 80°C to obtain a modified boron nitride filler (BN-1);

[0059] Weigh 107 liquid silicone rubber (33 g, 1 mmol) and place it in a 250 ml reaction container, add an appropriate amount of tetrahydrofuran to dissolve and mix evenly, add a solution of boric acid (0.063 g, 1 mmol) fully dissolved in ethanol reagent, stir evenly at 60 ° C to obtain a synthesized polymer solution, weigh and add 40 wt% modified boron nitride filler (22 g) to the polymer solution, stir mechanically at a constant temperature for 0.5-1 h to obtain a viscous polymer solution, and place it in an 80 ° C oven for curing for 24 h to obtain the target thermal conductive composite material.

[0060] Example 5

[0061] Weigh the boron nitride filler in flake form, add 3-6 times the mass fraction of sucrose, mix evenly, dissolve in deionized water, and place in a sealed zirconia ball mill. The ball mill speed is 500 rad / min. After ball milling for 12 hours, wash the filler with deionized water several times, and dry at 80°C to obtain a modified boron nitride filler (BN-1);

[0062] Weigh 107 liquid silicone rubber (33g, 1mmol) and place it in a 250ml reaction container, add an appropriate amount of tetrahydrofuran to dissolve and mix evenly, add a solution of boric acid (0.063g, 1mmol) fully dissolved in ethanol reagent, stir evenly at 60°C to obtain a synthesized polymer solution. Weigh and add 50wt% modified boron nitride filler (33g) to the polymer solution, stir mechanically at a constant temperature for 0.5-1h to obtain a viscous polymer solution, and place it in an 80°C oven for curing for 24h to obtain the target thermal conductive composite material.

[0063] Example 6

[0064] Weigh the boron nitride filler in flake form, add 3-6 times the mass fraction of sucrose, mix evenly, dissolve in deionized water, and place in a sealed zirconia ball mill. The ball mill speed is 500 rad / min. After ball milling for 12 hours, wash the filler with deionized water several times, and dry at 80°C to obtain a modified boron nitride filler (BN-1);

[0065] Weigh 107 liquid silicone rubber (33g, 1mmol) and place it in a 250ml reaction container, add an appropriate amount of tetrahydrofuran to dissolve and mix evenly, add a solution of boric acid (0.063g, 1mmol) fully dissolved in ethanol reagent, stir evenly at 60°C to obtain a synthesized polymer solution. Weigh and add 55wt% modified boron nitride filler (40.33g) to the polymer solution, stir mechanically at a constant temperature for 0.5-1h to obtain a viscous polymer solution, and place it in an 80°C oven for curing for 24h to obtain the target thermal conductive composite material.

[0066] The performance tests of the thermally conductive composite materials obtained in Examples 1 to 5 are shown in the following table:

[0067] Thermal conductivity (W / m·K) Interface thermal resistance (K·cm2 / W) Elongation(%) Example 1 0.21 1.33 950 Example 2 0.19 3.76 680 Example 3 1.6 0.26 1050 Example 4 2.46 0.29 909 Example 5 3.44 0.33 879 Example 6 5.6 0.38 865

[0068] The polysiloxane flexible thermal interface materials prepared in Examples 1-6 are applied to electronic devices to ensure long-term thermal reliability during use. Given its multifunctional properties, this advanced thermally conductive composite material shows great application potential in thermal interface materials for flexible electronics, electronic packaging, and organic substrates.

[0069] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be arranged and combined, and those skilled in the art can exhaust all possibilities based on the mathematical knowledge of arrangement and combination. Therefore, the present invention will no longer describe the technical solutions after arrangement and combination one by one, but it should be understood that the technical solutions after arrangement and combination have been disclosed by the present invention.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high thermal conductivity self-repairing thermally conductive composite material, characterized in that: The high thermal conductivity self-repairing thermal conductive composite material is composed of polysiloxane polymer, boric acid, and modified boron nitride filler; The mass fraction of the polysiloxane polymer is 40-60 parts, the mass fraction of boric acid is 0.1-0.5 parts, and the mass fraction of the modified boron nitride filler is 40-60 parts.

2. The high thermal conductivity self-repairing thermal conductive composite material according to claim 1, characterized in that: The polysiloxane polymer is one or more of silanol-terminated polydimethylsiloxane and alkanehydroxy-terminated polydimethylsiloxane.

3. The high thermal conductivity self-repairing thermally conductive composite material according to claim 1, characterized in that: The viscosity of the polysiloxane polymer is one or more of 1000, 1500, 3000, and 4000 cp·s.

4. A method for preparing a high thermal conductivity self-repairing thermally conductive composite material, characterized in that: Weigh a polysiloxane polymer, add tetrahydrofuran to dissolve and mix evenly, add a boric acid solution fully dissolved in an ethanol reagent, heat and stir, after stirring evenly, add a modified boron nitride filler, stir evenly at a constant temperature to obtain a viscous polymer solution, place it in an 80°C oven to cure for 24 hours, and obtain a high thermal conductivity self-healing thermally conductive composite material.

5. The method for preparing a high thermal conductivity self-repairing thermally conductive composite material according to claim 4, characterized in that: After adding the boric acid solution, the temperature is raised to 60° C. and stirring is started. The constant temperature stirring time is 0.5-1 h.

6. A method for preparing a modified boron nitride filler, characterized in that: Weigh the boron nitride filler, add 3-6 times the mass fraction of the modifier, mix evenly, dissolve in deionized water, place in a closed ball mill for ball milling, then wash the filler with deionized water for multiple times, and dry at 80° C. to obtain a modified boron nitride filler.

7. The method for preparing a modified boron nitride filler according to claim 6, characterized in that: The particle size of the boron nitride filler is one or more of 50 μm, 40 μm, 30 μm, 20 μm, 10 μm, 5 μm, and 2 μm.

8. The method for preparing a modified boron nitride filler according to claim 6, characterized in that: The material of the ball mill is one of zirconia, stainless steel, nylon and agate.

9. The method for preparing a modified boron nitride filler according to claim 6, characterized in that: The ball mill speed is 500 rad / min, and the ball milling time is 12 h.