Modification grafting method of high-thermal-conductivity organic silicon resin

Abstract

The invention discloses a modification grafting method of high-thermal-conductivity organic silicon resin, relates to the field of high-thermal-conductivity polymer materials, and is used for solving the problem that the existing organic silicon resin is poor in thermal conductivity and heat resistance. The high-thermal-conductivity organic silicon resin prepared by the invention mainly comprises the following components: vinyl organic silicon resin, high-thermal-conductivity functional filler, an initiator and styrene. The organic silicon resin with a novel structure and rich in hydrogen bonds is synthesized from the angle of creating a high-thermal-conductivity high polymer material, the compatibility of an organic-inorganic interface is improved through an in-situ polymerization method, the dispersion state of the high-thermal-conductivity filler is regulated and controlled by means of a double-percolation theory, a synergistic effect and the like, and the high-thermal-conductivity high polymer material is obtained. A network structure with both heat conduction and mechanical properties is constructed, and the high-heat-conduction organic silicon resin with high heat conduction and heat resistance as well as insulation and relatively high mechanical properties is prepared.

Description

Technical Field

[0001] The invention belongs to the field of high thermal conductivity polymer materials, and in particular relates to a modification and grafting method of a high thermal conductivity organic silicon resin. Background Art

[0002] Silicone resin is a highly cross-linked polysiloxane material with a three-dimensional network structure. It is usually prepared by hydrolysis and condensation reaction of multifunctional organosilane monomers under the action of catalysts such as alkali or acid. Silicone resin can also undergo further cross-linking reaction under the action of catalysts or heating conditions, and finally solidify into an insoluble and infusible thermosetting resin. The main chain of silicone resin is a Si-O-Si structure similar to inorganic materials, while the side chains mainly include organic groups such as methyl, vinyl and phenyl. This unique molecular structure gives silicone resin a series of excellent properties, including heat resistance, weather resistance, electrical insulation and chemical stability. These properties enable silicone resin to maintain stable performance over a wide temperature range and show good resistance to most chemicals. Therefore, silicone resin has shown extremely high application value in many fields, especially in industries such as aerospace, electronics and electrical, construction and transportation. It is widely used in sealing, bonding, coating and packaging to meet the high performance requirements of these industries for materials.

[0003] In recent years, with the continuous increase in the power density of semiconductor devices, the demand for electronic packaging materials and thermal interface materials that can conduct heat efficiently has been growing. The key role of these materials is to quickly conduct the heat generated by the device to prevent damage caused by overheating, thereby avoiding potential safety hazards. Although silicone resins have been widely used in the field of electronic packaging due to their excellent electrical insulation, chemical stability and flexibility, their low thermal conductivity has become the main obstacle to their wider application in high-performance electronic packaging and thermal management solutions.

[0004] In order to overcome this limitation, it is necessary to explore various methods to improve the thermal conductivity of silicone resins. These methods include but are not limited to adding high thermal conductivity fillers and developing new silicone composites, with the goal of enhancing their thermal conductivity while retaining the advantages of the original materials. At present, there are reports on the use of high thermal conductivity metal particles, metal oxides and ceramic particles as thermally conductive fillers, which are mixed into silicone resins to improve the thermal conductivity of the overall composite material. However, in actual operation, since the thermally conductive filler particles are easily isolated from each other by the silicone resin, it is difficult to achieve uniform distribution. Therefore, it is difficult to build an effective thermal conductive network, which limits the further improvement of the overall thermal conductivity of the composite material.

[0005] Therefore, providing a silicone resin with excellent thermal conductivity and heat resistance is a technical problem to be solved urgently in this field. Summary of the invention

[0006] The object of the present invention is to provide a high thermal conductivity silicone resin with high thermal conductivity and heat resistance, as well as insulation and high mechanical properties. By treating with a vinyl silane coupling agent, a vinyl group is introduced on the surface of the high thermal conductivity material, so that the high thermal conductivity material can be dispersed more evenly in the vinyl silicone resin, which not only reduces the gaps between the high thermal conductivity functional fillers, but also reduces the interface thermal resistance between the high thermal conductivity fillers and the vinyl silicone resin, thereby improving the overall thermal conduction efficiency of the silicone resin. Specifically, the technical solution of the present invention includes the following contents: A method for modifying and grafting a high thermal conductivity silicone resin comprises the following steps: A high thermal conductivity functional filler, an initiator and styrene are added to a vinyl silicone resin respectively, and a mixed solution is obtained after ultrasonic treatment for 3 to 4 hours in an environment with a power of 40 to 80 W. The mixed solution is poured into a mold, vacuum degassed, heated to 45 to 80° C., reacted for 1 to 2 hours, and then heated to 80 to 105° C., and reacted for 2 to 3 hours to obtain the high thermal conductivity silicone resin.

[0007] Furthermore, the preparation method of the vinyl silicone resin comprises the following steps: Vinyl silane, aminosilane and alkoxysilane are dispersed in isopropanol, and deionized water is added to prepare a mixed solution after ultrasonic treatment at 40 to 80 W for 30 to 60 minutes. The pH value of the mixed solution is adjusted to 5, and the mixture is reacted in an environment of 40 to 50° C. for 3 to 4 hours. After the reaction, the pH value of the mixed solution is adjusted to 8. After stirring for 1 to 2 hours, the product is collected by rotary evaporation, and the product is washed with water until the pH value is 7 and then vacuum dried to obtain the vinyl silicone resin.

[0008] Furthermore, the preparation method of the high thermal conductivity functional filler comprises the following steps: The high thermal conductivity material is dispersed in isopropanol, and ultrasonic dispersion is performed to obtain a high thermal conductivity material dispersion liquid. Tetraethyl orthosilicate is added to the high thermal conductivity material dispersion liquid and stirred for reaction at 25° C. for 2 to 3 hours. After the stirring is completed, a vinyl silane coupling agent is added and the stirring reaction is continued for 4 to 6 hours. After the reaction is completed, the high thermal conductivity functional filler is obtained by washing with water and drying.

[0009] Furthermore, the deionized water is used in an amount such that the weight ratio of the deionized water to the total weight of the vinyl silane, the amino silane and the alkoxy silane is 1:1.

[0010] Furthermore, the vinyl silicone resin is a polymer of vinyl silane, aminosilane and alkoxysilane.

[0011] Furthermore, the vinyl silane includes any one of vinyl trimethoxy silane, vinyl triethoxy silane or vinyl tri(2-methoxyethoxy) silane.

[0012] Furthermore, the aminosilane includes any one of γ-aminopropyltriethoxysilane (KH-550) or N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane (KH-792).

[0013] Furthermore, the alkoxysilane includes any one of methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane or propyltriethoxysilane.

[0014] Furthermore, the weight ratio of the vinyl silane, amino silane and alkoxy silane is 5-7:1:2-3.

[0015] Furthermore, the high thermal conductivity material is a mixture of at least two of carbon nanotubes, aluminum nitride or graphene nanosheets.

[0016] Furthermore, the components in the high thermal conductivity material include 0.5 to 2 parts of carbon nanotubes, 5 to 10 parts of aluminum nitride or 0.5 to 2 parts of graphene nanosheets by weight.

[0017] Furthermore, the vinyl silane coupling agent includes any one of vinyl trimethoxy silane, vinyl triethoxy silane, methyl vinyl diethoxy silane, methacryloxypropyl trimethoxy silane or methacryloxypropyl triethoxy silane.

[0018] Furthermore, the weight ratio of the high thermal conductivity material, tetraethyl orthosilicate and vinyl silane coupling agent is 1:0.5-1.5:1-1.5.

[0019] Furthermore, the power of the ultrasonic dispersion is 40 to 80 W, and the time of the ultrasonic dispersion is 3 to 4 hours.

[0020] Furthermore, the weight ratio of the vinyl silicone resin, the high thermal conductive functional filler, the initiator and styrene is 100:100-200:0.05-0.15:5-10.

[0021] Furthermore, the initiator includes any one of diisopropyl peroxide, dibenzoyl peroxide or benzoyl peroxide.

[0022] Furthermore, the vacuum degree of the vacuum degassing is 0.08-0.10 MPa, and the time of the vacuum degassing is 20-30 min.

[0023] Compared with the prior art, the present invention has the following beneficial effects: (1) From the perspective of creating high thermal conductivity polymer materials, synthesize high-density hydrogen-bonded silicone resins with new structures. Specifically, improve the organic-inorganic interface through in-situ polymerization, and use double percolation theory and synergistic effects to regulate the distribution state of high thermal conductivity functional fillers to perform thermal conductivity modification, thereby preparing silicone resins with high thermal conductivity and heat resistance, good insulation properties and high mechanical strength.

[0024] (2) The vinyl groups in the vinyl silane coupling agent cross-link with the vinyl groups in the vinyl silicone resin through free radical polymerization to form a three-dimensional network structure. The high thermal conductivity functional filler establishes a physical and chemical bond with the silicone resin through the vinyl silane coupling agent. This bonding method increases the interaction between the high thermal conductivity functional filler and the vinyl silicone resin, making it difficult for the high thermal conductivity functional filler to fall off from the vinyl silicone resin, thereby ensuring that the final silicone resin has higher thermal conductivity. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be clearly and completely described below through the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0026] Unless otherwise specified, the raw materials and reagents used in the present invention are commercially available or can be prepared by known methods.

[0027] Preparation Example 1 The preparation of vinyl silicone resin specifically includes the following processes: Disperse 50 parts of vinyltrimethoxysilane, 10 parts of γ-aminopropyltriethoxysilane (KH-550) and 20 parts of methyltriethoxysilane in 200 parts of isopropanol, add 80 parts of deionized water to prepare a mixed solution after 40W ultrasound for 30 minutes, adjust the pH value of the mixed solution to 5, stir and react for 3 hours at 40°C, adjust the pH value of the mixed solution to 8 after the reaction, stir and react for 1 hour, collect the product by rotary evaporation, wash the product with water until the pH value reaches 7, and then vacuum dry to obtain vinyl silicone resin.

[0028] Preparation Example 2 The preparation of vinyl silicone resin specifically includes the following processes: 60 parts of vinyl triethoxysilane, 10 parts of N-β-(aminoethyl)-γ-aminopropyl trimethoxysilane (KH-792) and 25 parts of ethyl trimethoxysilane were dispersed in 200 parts of isopropanol, and 95 parts of deionized water were added to prepare a mixed solution after 60W ultrasound for 40 minutes. The pH value of the mixed solution was adjusted to 5, and the reaction was stirred at 45°C for 3.5 hours. After the reaction, the pH value of the mixed solution was adjusted to 8. After stirring for 1.5 hours, the product was collected by rotary evaporation, washed with water until the pH value reached 7, and then vacuum dried to obtain a vinyl silicone resin.

[0029] Preparation Example 3 The preparation of vinyl silicone resin specifically includes the following processes: 70 parts of vinyl tri(2-methoxyethoxy)silane, 10 parts of γ-aminopropyl triethoxysilane (KH-550) and 30 parts of ethyl triethoxysilane were dispersed in 200 parts of isopropanol, and 110 parts of deionized water were added to prepare a mixed solution after 80W ultrasound for 60 minutes. The pH value of the mixed solution was adjusted to 5, and the mixture was stirred and reacted at 50°C for 4 hours. After the reaction, the pH value of the mixed solution was adjusted to 8. After stirring and reacting for 2 hours, the product was collected by rotary evaporation, washed with water until the pH value reached 7, and then vacuum dried to obtain a vinyl silicone resin.

[0030] Preparation Example 4 The preparation of high thermal conductivity functional filler specifically includes the following processes: Disperse 5 parts of carbon nanotubes and 50 parts of aluminum nitride in 200 parts of isopropanol, and obtain a dispersion by ultrasonic dispersion at 40W for 3 hours. Add 27.5 parts of tetraethyl orthosilicate to the dispersion, and stir to react at 25°C for 2 hours. After stirring, add 55 parts of vinyltrimethoxysilane and stir to react for 4 hours. After the reaction, wash with water and dry to obtain a high thermal conductivity functional filler.

[0031] Preparation Example 5 The preparation of high thermal conductivity functional filler specifically includes the following processes: 80 parts of aluminum nitride and 10 parts of graphene nanosheets were dispersed in 400 parts of isopropanol, and ultrasonic dispersion was performed at 50W for 3.5 hours to obtain a dispersion. 90 parts of ethyl orthosilicate were added to the dispersion and stirred for reaction at 25°C for 2.5 hours. After the stirring, 110 parts of methylvinyldiethoxysilane were added and stirred for reaction for 5 hours. After the reaction, the high thermal conductivity functional filler was obtained by washing with water and drying.

[0032] Preparation Example 6 The preparation of high thermal conductivity functional filler specifically includes the following processes: 2 parts of carbon nanotubes, 10 parts of aluminum nitride and 2 parts of graphene nanosheets were dispersed in 200 parts of isopropanol, and ultrasonic dispersion was performed at 60W for 4 hours to obtain a dispersion. 21 parts of ethyl orthosilicate were added to the dispersion and stirred for reaction at 25°C for 3 hours. After the stirring, 21 parts of methacryloxypropyltrimethoxysilane were added and stirred for reaction for 6 hours. After the reaction, the high thermal conductivity functional filler was obtained by washing with water and drying.

[0033] Preparation Example 7 The preparation of high thermal conductivity functional filler specifically includes the following processes: 10 parts of carbon nanotubes and 5 parts of graphene nanosheets were dispersed in 300 parts of isopropanol, and ultrasonic dispersion was performed at 80W for 4 hours to obtain a dispersion. 22.5 parts of tetraethyl orthosilicate were added to the dispersion and stirred for reaction at 25°C for 3 hours. After the stirring, 20 parts of methacryloxypropyltriethoxysilane were added and stirred for reaction for 6 hours. After the reaction, the high thermal conductivity functional filler was obtained by washing with water and drying.

[0034] Example 1

[0035] A modification and grafting method of a high thermal conductivity silicone resin specifically includes the following steps: Take 100 parts of the high thermal conductivity functional filler in Preparation Example 4, 0.05 parts of diisopropyl peroxide and 5 parts of styrene, add them to 100 parts of the vinyl silicone resin in Preparation Example 1, and obtain a mixed solution after ultrasonic treatment in an environment with a power of 40 W for 3 hours. Pour the mixed solution into a mold, vacuum degasse for 20 minutes in a vacuum degree of 0.08 MPa, then heat it to 45°C in a standard atmospheric pressure environment, react at this temperature for 1 hour, and then heat it to 80°C, and react at this temperature for another 2 hours to obtain a high thermal conductivity silicone resin.

[0036] Example 2

[0037] A method for preparing a high thermal conductive silicone resin specifically comprises the following steps: Take 120 parts of the high thermal conductivity functional filler in Preparation Example 5, 0.1 parts of dibenzoyl peroxide and 8 parts of styrene, add them to 100 parts of the vinyl silicone resin in Preparation Example 2, and obtain a mixed solution after ultrasonic treatment for 3.5 hours in an environment with a power of 60 W. The mixed solution is poured into a mold, vacuum degassed at a vacuum degree of 0.09 MPa for 25 minutes, then heated to 60°C in a standard atmospheric pressure environment, reacted at this temperature for 1.5 hours, and then heated to 90°C, and reacted at this temperature for another 2.5 hours to obtain a high thermal conductivity silicone resin.

[0038] Example 3

[0039] A method for preparing a high thermal conductive silicone resin specifically comprises the following steps: Take 150 parts of the high thermal conductivity functional filler in Preparation Example 6, 0.15 parts of benzoyl peroxide and 10 parts of styrene, add them to 100 parts of the vinyl silicone resin in Preparation Example 3, and obtain a mixed solution after ultrasonic treatment in an environment with a power of 80 W for 4 hours. Pour the mixed solution into a mold, vacuum degasse for 30 minutes in a vacuum degree of 0.10 MPa, then heat it to 80°C in a standard atmospheric pressure environment, react at this temperature for 2 hours, and then heat it to 105°C, and react at this temperature for another 3 hours to obtain a high thermal conductivity silicone resin.

[0040] Example 4

[0041] A method for preparing a high thermal conductive silicone resin specifically comprises the following steps: Take 200 parts of the high thermal conductivity functional filler in Preparation Example 7, 0.1 parts of benzoyl peroxide and 8 parts of styrene, add them to 100 parts of the vinyl silicone resin in Preparation Example 3, and obtain a mixed solution after ultrasonic treatment in an environment with a power of 80 W for 4 hours. Pour the mixed solution into a mold, vacuum degasse for 25 minutes in a vacuum degree of 0.10 MPa, then heat it to 75°C in a standard atmospheric pressure environment, react at this temperature for 2 hours, and then heat it to 105°C, and react at this temperature for another 3 hours to obtain a high thermal conductivity silicone resin.

[0042] Comparative Example 1 A modification and grafting method of a high thermal conductivity silicone resin specifically includes the following steps: The γ-aminopropyltriethoxysilane (KH-550) in Preparation Example 3 was removed, and the other operations were consistent with Example 3.

[0043] Comparative Example 2 A modified grafting method for a high thermal conductivity silicone resin specifically includes the following steps: The ethyltriethoxysilane in Preparation Example 3 was removed, and the other operations were consistent with Example 3.

[0044] Comparative Example 3 A modification and grafting method of a high thermal conductivity silicone resin specifically includes the following steps: The high thermal conductivity functional filler in Example 3 was replaced with boron nitride, and other operations were consistent with Example 3.

[0045] Test Example 1: Thermal conductivity test and tensile strength test The silicone resins prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were tested for thermal conductivity according to GASTM D5470 and for tensile strength according to HG / T2580-90. The results are shown in Table 1.

[0046] Table 1. Thermal conductivity and tensile strength of silicone resins in Examples 1 to 4 and Comparative Examples 1 to 3 project Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Thermal conductivity (W / m·K) 3.51 3.73 3.87 3.96 1.93 1.84 2.27 Tensile strength (MPa) 0.75 0.83 0.89 0.85 0.64 0.59 0.53 As shown in Table 1, the thermal conductivity and tensile properties of the silicone resins prepared in Examples 1 to 4 are significantly better than those of the silicone resins prepared in Comparative Examples 1 to 3. In the present invention, the addition of high thermal conductivity functional fillers not only improves the thermal conductivity of the silicone resin, but also improves other properties of the silicone resin. However, by comparing the tensile strength of the silicone resins prepared in Examples 1 to 4, it can be seen that when the addition amount of high thermal conductivity functional fillers is too much, the performance of the silicone resin will also decrease.

[0047] Test Example 2: Thermogravimetric analysis to test heat resistance Thermogravimetric analysis was performed on the organic silicon resins prepared in Examples 1 to 4 and Comparative Examples 1 to 3 to detect their heat resistance. The test conditions were as follows: under nitrogen protection, the temperature was increased at a rate of 10° C. / min, and the temperature range was 25 to 500° C.

[0048] Table 2. Thermogravimetric analysis results of silicone resins in Examples 1 to 4 and Comparative Examples 1 to 3 project Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 T5%（℃） 294 301 310 317 236 221 249 Tmax(℃) 317 336 354 361 251 243 275 Residual weight rate (%) 78.1 80.3 82.7 83.2 63.8 61.4 64.6 According to the comparison between Examples 1 to 4 and Comparative Examples 1 to 3 in Table 2, it can be seen that the addition of high thermal conductivity fillers can effectively improve the high temperature resistance of the silicone resin, so that more residual weight is retained, indicating that the silicone resin prepared in Examples 1 to 4 has good heat resistance.

[0049] The above-described embodiments provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected.

Claims

1. A modification and grafting method of a high thermal conductivity silicone resin, characterized in that: The following steps are involved: A high thermal conductivity functional filler, an initiator and styrene are added to a vinyl silicone resin respectively, and a mixed solution is obtained after ultrasonic treatment for 3 to 4 hours in an environment with a power of 40 to 80 W. The mixed solution is poured into a mold, vacuum degassed, heated to 45 to 80° C., reacted for 1 to 2 hours, and then heated to 80 to 105° C., and reacted for 2 to 3 hours to obtain the high thermal conductivity silicone resin.

2. The modification and grafting method of a high thermal conductivity silicone resin according to claim 1, characterized in that: The preparation method of the high thermal conductivity functional filler comprises the following steps: The high thermal conductivity material is dispersed in isopropanol, and ultrasonic dispersion is performed to obtain a high thermal conductivity material dispersion liquid. Tetraethyl orthosilicate is added to the high thermal conductivity material dispersion liquid and stirred for reaction at 25° C. for 2 to 3 hours. After the stirring is completed, a vinyl silane coupling agent is added and the stirring reaction is continued for 4 to 6 hours. After the reaction is completed, the high thermal conductivity functional filler is obtained by washing with water and drying.

3. The modification and grafting method of a high thermal conductivity silicone resin according to claim 2, characterized in that: The high thermal conductivity material is a mixture of at least two of carbon nanotubes, aluminum nitride or graphene nanosheets.

4. The modification and grafting method of a high thermal conductivity silicone resin according to claim 2, characterized in that: The weight ratio of the high thermal conductivity material, tetraethyl orthosilicate and vinyl silane coupling agent is 1:0.5-1.5:1-1.

5.

5. The modification and grafting method of a high thermal conductivity silicone resin according to claim 2, characterized in that: The power of the ultrasonic dispersion is 40-80W, and the time of the ultrasonic dispersion is 3-4h.

6. The modification and grafting method of a high thermal conductivity silicone resin according to claim 1, characterized in that: The vinyl silicone resin is a polymer of vinyl silane, amino silane and alkoxy silane.

7. The modification and grafting method of a high thermal conductivity silicone resin according to claim 6, characterized in that: The weight ratio of the vinyl silane, amino silane and alkoxy silane is 5-7:1:2-3.

8. The modification and grafting method of a high thermal conductivity silicone resin according to claim 1, characterized in that: The weight ratio of the vinyl silicone resin, the high thermal conductive functional filler, the initiator and styrene is 100:100-200:0.05-0.15:5-10.

9. The modification and grafting method of a high thermal conductivity silicone resin according to claim 1, characterized in that: The vacuum degree of the vacuum degassing is 0.08-0.10 MPa, and the time of the vacuum degassing is 20-30 min.

10. A high thermal conductivity organic silicone resin prepared by the modification and grafting method of a high thermal conductivity organic silicone resin according to any one of claims 1 to 9.