A heat-conducting silicone composition, a preparation method and application thereof

Abstract

The application provides a heat-conducting organic silicon composition, a preparation method and application thereof, and the heat-conducting organic silicon composition comprises 80-100 mass parts of organic polysiloxane, 800-1500 mass parts of heat-conducting filler and 2-10 mass parts of star-shaped polysiloxane; the star-shaped polysiloxane has a three-dimensional telechelic structure, the molecular chain end of the star-shaped polysiloxane is provided with an alkoxy group, the star-shaped polysiloxane can be condensed with the hydroxyl group on the surface of the filler to act on multiple filler particles, the surface treatment capacity of a single molecule of the star-shaped polysiloxane is far more than that of a conventional silane coupling agent or a mono-alkoxy-terminated polysiloxane, the star-shaped polysiloxane can help to improve the wettability and dispersibility of the heat-conducting filler in the organic polymer and reduce the interfacial thermal resistance between the heat-conducting filler and the organic polymer under the same amount, so as to meet the multiple requirements of low thermal resistance, thin layer interface and good construction performance of the heat-conducting interface material.

Description

Technical Field

[0001] This invention relates to the field of thermally conductive compositions, and particularly to a thermally conductive organosilicon composition, its preparation method, and its application. Background Technology

[0002] In recent years, new-generation information technologies such as artificial intelligence (AI), cloud computing, big data, and the Internet of Things have developed rapidly and are increasingly integrated into key sectors of the national economy, including manufacturing, transportation, education, energy, healthcare, and finance. As the core engine driving intelligent transformation, computing power is experiencing explosive growth in demand. To meet increasingly complex computing tasks and real-time processing requirements, chips are evolving towards higher integration, higher frequencies, and higher power densities. However, the enhancement of chip functionality and the leap in performance inevitably come with a significant increase in power consumption. At the same time, the trend towards miniaturization and thinner designs in electronic devices has placed extremely stringent constraints on internal space. This contradiction between increased power consumption and reduced space makes heat dissipation within electronic devices an unprecedented challenge. Efficient thermal management has become a core challenge for ensuring system stability, reliability, and extending lifespan.

[0003] Thermal interface materials, serving as a crucial bridge for heat transfer between chips and heat sinks, must meet multiple requirements in practical applications, including low thermal resistance, ease of construction, and high reliability. Thermal interface materials typically incorporate a large amount of thermally conductive fillers. To improve the compatibility between these fillers and polymers, surface modification of the fillers using silane coupling agents and single-ended alkoxy-terminated polysiloxanes has been widely reported and applied. However, the problem of insufficient long-term durability in existing thermal interface materials remains prevalent. During device operation, chips undergo repeated start-stop cycles or load changes, leading to drastic temperature cycling. Conventional surface treatment agents have short molecular chains, resulting in weak bonding between the treated thermally conductive fillers and polymers. Under the combined effects of cyclic shear / peel stress caused by differences in interface CTE and thermal stress, thermal interface materials are prone to phase separation, cracking, hardening, and pulverization, leading to contact failure and increased thermal resistance at the interface.

[0004] Therefore, it is of great significance to prepare efficient treatment agents for surface coating modification of thermally conductive fillers, improve the compatibility and bonding ability between thermally conductive fillers and polymers, and obtain thermal interface materials with excellent thermal conductivity, easy construction and long-term reliability. Summary of the Invention

[0005] This invention provides a thermally conductive organosilicon composition, its preparation method, and its application, with the aim of solving the aforementioned problems existing in the background art.

[0006] To achieve the above objectives, embodiments of the present invention provide a thermally conductive organosilicon composition, its preparation method, and its application. A thermally conductive silicone composition comprising 80-100 parts by weight of an organopolysiloxane, 800-1500 parts by weight of a thermally conductive filler, and 2-10 parts by weight of a star-shaped polysiloxane; preferably, 2.2-7.9 parts by weight of the star-shaped polysiloxane. The star-shaped polysiloxane has the following structural formula (I):

[0007] Equation (I); where a and b are 0, 1, or 2; R a Selected from any one of methyl, ethyl, isopropyl, tert-butyl, octyl, dodecyl, octadecyl, and phenyl; R b 'Selected from any one of ethylenetrimethoxysilyl, ethylenetriethoxysilyl, ethylenetrimethoxyethoxysilyl, ethylenetriisopropoxysilyl, propylenetrimethoxysilyl, propylenetriethoxysilyl, and propylenetrimethoxyethoxysilyl; preferably, R a Selected from methyl, tert-butyl, octyl, and phenyl; R b Selected from ethylenetrimethoxysilyl or propylenetriethoxysilyl; X is selected from the following structural formula (II):

[0008] Formula (II); n is a positive integer from 3 to 100; Y is an alkylene group with 6 or fewer carbon atoms; Y is preferably ethylene or propylene; R1, R2 and R3 can be selected from any one of straight-chain alkyl, branched alkyl, cycloalkyl, alkenyl, aryl, aralkyl and epoxy groups; R1 and R2 can be the same or different, and R1 and R2 are preferably methyl, vinyl, 2,3-epoxypropoxypropyl, trifluoropropyl or phenyl; R1 and R2 are more preferably methyl or phenyl; R3 is preferably methyl; R4 can be selected from any one of straight-chain alkyl, branched alkyl, cycloalkyl, alkenyl, aryl, aralkyl or epoxy groups; R4 is preferably methyl or ethyl.

[0009] Preferably, the star-shaped polysiloxane is selected from compounds 1-7: Compound 1: , Compound 2: , Compound 3: , Compound 4: , Compound 5: , Compound 6: , Compound 7: .

[0010] Preferably, the method for preparing the star-shaped polysiloxane includes the following steps: S1: The cyclic organosiloxane monomer is dissolved in an organic solvent and subjected to a ring-opening polymerization reaction with the organosilane alkoxide in an ice-water bath under an inert atmosphere. After the reaction is completed, chlorosilane is added to carry out a bridging reaction. After the reaction is completed, the target intermediate is obtained by de-molecularization, impurity removal and drying. S2: The target intermediate is subjected to a hydrosilylation reaction with an organosilane to prepare the star-shaped polysiloxane.

[0011] Preferably, in step S1, the cyclic organosiloxane monomer is selected from at least one of hexamethylcyclotrisiloxane, 2,4,6-trimethyl-2,4,6-trivinylcyclotrisiloxane, 2,4,6-trimethyl-2,4,6-triphenylcyclotrisiloxane, 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane, hexaphenylcyclotrisiloxane, octamethylcyclotetrasiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetraphenylcyclotetrasiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetra(propylglycidyl ether)cyclotetrasiloxane, octaphenylcyclotetrasiloxane, and decamethylcyclopentasiloxane.

[0012] Preferably, in step S1, the organosilanal alkoxide has the following structural formula (III):

[0013] Formula (III); wherein R3 can be selected from any one of straight-chain alkyl, branched alkyl, cycloalkyl, alkenyl, aryl, aralkyl and epoxy groups; R3 is preferably methyl, vinyl, 2,3-epoxypropoxypropyl, trifluoropropyl or phenyl; R5 can be selected from vinyl or allyl; M is sodium or potassium.

[0014] Preferably, in step S1, the chlorosilane is selected from at least one of tetrachlorosilane, methyltrichlorosilane, ethyltrichlorosilane, vinyltrichlorosilane, phenyltrichlorosilane, phenethyltrichlorosilane, allyltrichlorosilane, octyltrichlorosilane, dodecyltrichlorosilane, octadecyltrichlorosilane, dimethyldichlorosilane, diethyldichlorosilane, diisopropyldichlorosilane, di-tert-butyldichlorosilane, dioctyldichlorosilane, diphenyldichlorosilane, methylvinyldichlorosilane, and methylallyldichlorosilane.

[0015] Preferably, in step S2, the organosilane is selected from at least one of trimethoxysilane, triethoxysilane, trimethoxyethoxysilane, and triisopropoxysilane.

[0016] Preferably, the thermally conductive filler includes at least two fillers with different particle sizes; wherein the filler is at least one of metal, metal oxide, metal nitride and carbon-containing material; and the average particle size of the thermally conductive filler is 0.01-20 μm.

[0017] More preferably, the filler is at least one of aluminum, silver, copper, zinc oxide, aluminum oxide, aluminum hydroxide, magnesium oxide, magnesium hydroxide, titanium dioxide, zirconium dioxide, silicon dioxide, aluminum nitride, boron nitride, silicon nitride, silicon carbide, diamond, graphite, carbon fiber, carbon nanotubes, and graphene.

[0018] Preferably, the thermally conductive silicone composition further includes a heat stabilizer with an average particle size of 10-500 nm; wherein the heat stabilizer is selected from any one of cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide.

[0019] Based on a general inventive concept, embodiments of the present invention provide a method for preparing the above-mentioned thermally conductive organosilicon composition, comprising the following steps: (1) Premix fillers of different particle sizes and dry them at 110~120℃ under nitrogen protection to obtain pretreated thermally conductive fillers; (2) Disperse the organopolysiloxane and star-shaped polysiloxane under nitrogen protection for 15-30 min; then add the pretreated thermally conductive filler, heat to 60-90℃ under nitrogen protection and disperse for 30-60 min, and finally add the heat stabilizer and mix for 20-30 min to prepare the thermally conductive organosilicon composition.

[0020] The embodiments of the present invention provide the application of the above-described thermally conductive silicone composition in thermal interface materials.

[0021] The above-described solution of the present invention has the following beneficial effects: (1) The star-shaped polysiloxane described in the above-mentioned scheme of the present invention has a three-dimensional teleclaw structure. Its molecular chain ends with alkoxy groups, which can undergo condensation reaction with the hydroxyl groups on the surface of the filler and act on multiple filler particles. Its surface treatment capability of a single molecule is far superior to that of conventional silane coupling agents or monoalkoxy-terminated polysiloxanes. Under the same dosage, it helps to improve the wettability and dispersibility of thermally conductive fillers in organic polymers and reduce the interfacial thermal resistance between thermally conductive fillers and organic polymers, so as to meet the multiple requirements of low thermal resistance, thin-layer interface and good construction performance of thermally conductive interface materials.

[0022] (2) In this invention, star-shaped polysiloxane is premixed with an organic polymer, which allows the molecular chains of the two to become entangled during the mixing process. When this mixture is added to a thermally conductive filler, the alkoxy groups at the ends of the star-shaped polysiloxane molecular chains undergo a condensation reaction with the hydroxyl groups on the filler surface, anchoring themselves to the filler particles. Since the star-shaped polysiloxane has already become entangled with the organic polymer molecular chains, this anchoring effect simultaneously fixes the organic polymer molecular chains to the filler surface, thereby forming an interpenetrating network structure at the filler-polymer interface. This structure significantly enhances the interfacial bonding force, enabling the thermally conductive composition of this invention to effectively resist aging effects such as high temperature, humid heat, and alternating hot and cold temperatures, preventing failure phenomena such as phase separation, cracking, powdering, or hardening, and maintaining the long-term integrity of the interface.

[0023] (3) The method for preparing star-shaped polysiloxane provided by the present invention uses cyclosiloxane as raw material and organosilane alkoxide as initiator. After ring-opening polymerization, it is cross-linked with organochlorosilane to obtain intermediate. The intermediate is then hydrosilylated with organosilane to obtain star-shaped polysiloxane. It has the advantages of readily available raw materials, safe and controllable preparation method, simple process flow and high product yield, and is suitable for large-scale production. Detailed Implementation

[0024] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with specific embodiments.

[0025] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0026] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0027] This invention addresses existing problems by providing a thermally conductive organosilicon composition, its preparation method, and its applications. The following detailed description includes specific examples and comparative embodiments. Example 1 This embodiment provides a method for preparing star-shaped polysiloxanes, specifically including the following steps: S1. Dissolve 200 g (0.90 mol) of hexamethylcyclotrisiloxane in 200 ml of tetrahydrofuran, and add the solution to a four-necked flask equipped with a stirrer, thermometer, nitrogen, and reflux condenser. Under the protection of an ice-water bath and nitrogen, inject 400 ml of a tetrahydrofuran solution containing 22.1 g (0.178 mol) of sodium dimethylvinylsilanolate at a constant rate. Stir the reaction at 10–20 °C for 6 h. Then add 32.5 g (0.10 mol) of dioctyldichlorosilane to initiate a bridging reaction. Continue stirring at room temperature for 2 h until the pH of the solution is neutral. After the reaction is complete, remove the solvent and residual small molecule byproducts by rotary evaporation at 120 °C / -0.01 MPa. After cooling, add a dry 4 Å molecular sieve and filter to obtain the intermediate. The S1 reaction is as follows:

[0028] ; S2. Place 100 g of the above intermediate into a three-necked flask, add 0.045 g of caster catalyst (platinum content 5000 ppm), and slowly inject 10.75 g of trimethoxysilane. Maintain the reaction temperature at 50-60 °C for 2 h. After cooling to room temperature, remove unreacted and low-boiling substances by rotary evaporation at 120 °C / -0.01 MPa, finally obtaining 100.4 g of clear and transparent product, with a yield of 90.6%. The product has the following structure: .

[0029] The S2 reaction is as follows:

[0030] .

[0031] Example 2 This embodiment provides a method for preparing star-shaped polysiloxanes, specifically including the following steps: S1. Dissolve 200 g (0.90 mol) hexamethylcyclotrisiloxane in 200 ml toluene, add the solution to a four-necked flask equipped with a stirrer, thermometer, nitrogen, and reflux condenser. Under ice-water bath and nitrogen protection, inject 666 ml of a toluene solution containing 36.6 g (0.295 mol) sodium dimethylvinylsilanolate at a constant rate. Stir the reaction at 10–20 °C for 6 h. Then add 17.6 g (0.118 mol) methyltrichlorosilane to initiate a bridging reaction. Continue stirring at room temperature for 2 h until the pH of the solution is neutral. After the reaction is complete, remove the solvent and residual small molecule byproducts by rotary evaporation at 120 °C / -0.01 MPa. After cooling, add a dry 4 Å molecular sieve and filter to obtain the intermediate. S2. Place 100 g of the above intermediate into a three-necked flask, add 0.05 g of castor catalyst (platinum content 5000 ppm), and slowly inject 24.6 g of triethoxysilane. Maintain the reaction temperature at 50-60 °C for 2 h. After cooling to room temperature, remove unreacted and low-boiling substances by rotary evaporation at 120 °C / -0.01 MPa, finally obtaining 109.2 g of clear and transparent product, with a yield of 87.6%. The product has the following structure: .

[0032] Example 3 This embodiment provides a method for preparing star-shaped polysiloxanes, specifically including the following steps: S1. Dissolve 200 g (0.9 mol) of hexamethylcyclotrisiloxane in 200 ml of tetrahydrofuran, and add the solution to a four-necked flask equipped with a stirrer, thermometer, nitrogen, and reflux condenser. Under the protection of an ice-water bath and nitrogen, inject 500 ml of tetrahydrofuran solution containing 30.8 g (0.22 mol) of dimethylvinylsilanolate potassium at a constant rate. Stir the reaction at 10–20 °C for 6 h, then add 14.2 g (0.088 mol) of vinyltrichlorosilane to initiate a bridging reaction. Continue stirring at room temperature for 2 h until the pH of the solution is neutral. After the reaction is complete, remove the solvent and residual small molecule byproducts by rotary evaporation at 120 °C / -0.01 MPa. After cooling, add a dry 4 Å molecular sieve and filter to obtain the intermediate. S2. Place 100 g of the above intermediate into a three-necked flask, add 0.047 g of caster catalyst (platinum content 5000 ppm), and slowly inject 18.1 g of trimethoxysilane. Maintain the reaction temperature at 50-60 °C for 2 h. After cooling to room temperature, remove unreacted and low-boiling substances by rotary evaporation at 120 °C / -0.01 MPa, finally obtaining 97.9 g of clear and transparent product, with a yield of 82.9%. The product has the following structure: .

[0033] Example 4 This embodiment provides a method for preparing star-shaped polysiloxanes, specifically including the following steps: S1. Dissolve 200 g (0.49 mol) of 2,4,6-trimethyl-2,4,6-triphenylcyclotrisiloxane in 200 mL of n-hexane. Add the solution to a four-necked flask equipped with a stirrer, thermometer, nitrogen, and reflux condenser. Under ice-water bath and nitrogen protection, inject 250 mL of n-hexane solution containing 12.0 g (0.097 mol) of sodium dimethylvinylsilanolate at a constant rate. Stir the reaction at 10–20 °C for 6 h. Then add 11.9 g (0.056 mol) of di-tert-butyldichlorosilane for a bridging reaction. Continue stirring at room temperature for 2 h until the pH of the solution is neutral. After the reaction is complete, remove the solvent and residual small molecule byproducts by rotary evaporation at 120 °C / -0.01 MPa. After cooling, add a dry 4 Å molecular sieve and filter to obtain the intermediate. S2. Place 100 g of the above intermediate into a three-necked flask, add 0.043 g of caster catalyst (platinum content 5000 ppm), and slowly inject 6.8 g of trimethoxysilane. Maintain the reaction temperature at 50-60 °C for 2 h. After cooling to room temperature, remove unreacted and low-boiling substances by rotary evaporation at 120 °C / -0.01 MPa, finally obtaining 97.6 g of clear and transparent product, with a yield of 91.3%. The product has the following structure: .

[0034] Example 5 This embodiment provides a method for preparing star-shaped polysiloxanes, specifically including the following steps: S1. Dissolve 200 g (0.9 mol) hexamethylcyclotrisiloxane in 200 ml toluene, and add the solution to a four-necked flask equipped with a stirrer, thermometer, nitrogen, and reflux condenser. Under ice-water bath and nitrogen protection, inject 200 ml of toluene solution containing 12.5 g (0.089 mol) dimethylvinylsilanolate potassium at a constant rate. Stir the reaction at 10-20 °C for 6 h. Then add 8.1 g (0.052 mol) allylmethyldichlorosilane to initiate a bridging reaction. Continue stirring at room temperature for 2 h until the pH of the solution is neutral. After the reaction is complete, remove the solvent and residual small molecule byproducts by rotary evaporation at 120 °C / -0.01 MPa. After cooling, add dry 4 Å molecular sieve and filter to obtain the intermediate. S2. Place 100 g of the above intermediate into a three-necked flask, add 0.045 g of Castells catalyst (platinum content 5000 ppm), and slowly inject 10.7 g of triethoxysilane. Maintain the reaction temperature at 50-60 °C for 2 h. After cooling to room temperature, remove unreacted and low-boiling substances by rotary evaporation at 120 °C / -0.01 MPa, finally obtaining 104.8 g of clear and transparent product, with a yield of 94.6%. The product has the following structure: .

[0035] Example 6 This embodiment provides a method for preparing star-shaped polysiloxanes, specifically including the following steps: S1. Dissolve 200 g (0.9 mol) of hexamethylcyclotrisiloxane in 200 ml of tetrahydrofuran, and add the solution to a four-necked flask equipped with a stirrer, thermometer, nitrogen, and reflux condenser. Under the protection of an ice-water bath and nitrogen, inject 100 ml of a tetrahydrofuran solution containing 5.5 g (0.044 mol) of sodium dimethylvinylsilanolate at a constant rate. Stir the reaction at 10–20 °C for 6 h, then add 3.6 g (0.017 mol) of phenyltrichlorosilane to initiate a bridging reaction. Continue stirring at room temperature for 2 h until the pH of the solution is neutral. After the reaction is complete, remove the solvent and residual small molecule byproducts by rotary evaporation at 120 °C / -0.01 MPa. After cooling, add a dry 4 Å molecular sieve and filter to obtain the intermediate. S2. Place 100 g of the above intermediate into a three-necked flask, add 0.041 g of Castells catalyst (platinum content 5000 ppm), and slowly inject 2.8 g of trimethoxysilane. Maintain the reaction temperature at 50-60 °C for 2 h. After cooling to room temperature, remove unreacted and low-boiling substances by rotary evaporation at 120 °C / -0.01 MPa, finally obtaining 90.3 g of clear and transparent product, with a yield of 87.8%. The product has the following structure: .

[0036] Example 7 This embodiment provides a method for preparing star-shaped polysiloxanes, specifically including the following steps: S1. Dissolve 200 g (0.9 mol) of hexamethylcyclotrisiloxane in 200 mL of tetrahydrofuran, and add the solution to a four-necked flask equipped with a stirrer, thermometer, nitrogen, and reflux condenser. Under ice-water bath and nitrogen protection, inject 250 mL of tetrahydrofuran solution containing 13.9 g (0.099 mol) of dimethylvinylsilanolate potassium at a constant rate. Stir the reaction at 10–20 °C for 6 h, then add 4.76 g (0.028 mol) of tetrachlorosilane for a bridging reaction, and continue stirring at room temperature for 2 h until the pH of the solution is neutral. After the reaction is complete, remove the solvent and residual small molecule byproducts by rotary evaporation at 120 °C / -0.01 MPa. After cooling, add dry 4 Å molecular sieves and filter to obtain the intermediate. S2. Place 100 g of the above intermediate into a three-necked flask, add 0.042 g of Castells catalyst (platinum content 5000 ppm), and slowly inject 6.1 g of trimethoxysilane. Maintain the reaction temperature at 50-60 °C for 2 h. After cooling to room temperature, remove unreacted and low-boiling substances by rotary evaporation at 120 °C / -0.01 MPa, finally obtaining 86.2 g of clear and transparent product, with a yield of 81.2%. The product has the following structure: .

[0037] Example 8 This embodiment provides a method for preparing a thermally conductive silicone composition, comprising the following steps: (1) Pretreatment of thermally conductive filler: 150 parts by weight of zinc oxide powder with an average particle size of 0.1 micrometers, 200 parts by weight of spherical alumina powder with an average particle size of 1 micrometers and 650 parts by weight of spherical aluminum powder with an average particle size of 10 micrometers are placed in a V-type mixer for premixing and then dried under nitrogen protection and at 110~120℃ for later use. (2) 97.2 parts by mass of polydimethylsiloxane with a viscosity of 100 mPa•s and 2.2 parts by mass of star-shaped polysiloxane prepared in Example 1 were placed in a mixer with a heating jacket and dispersed for 15-30 min under nitrogen protection. Then, 1300 parts by mass of thermally conductive filler pretreated in step (1) were added and the material was heated and dispersed at high speed for 30-60 min under nitrogen protection and the material temperature was controlled at 60-90℃. Finally, 5.4 parts by mass of cerium oxide heat stabilizer with an average particle size of 200 nm were added and mixed for 20-30 min to obtain a thermally conductive organosilicon composition.

[0038] Example 9 This embodiment provides a method for preparing a thermally conductive silicone composition, comprising the following steps: (1) Pretreatment of thermally conductive filler: 325 parts by mass of zinc oxide powder with an average particle size of 0.2 micrometers, 195 parts by mass of quasi-spherical alumina powder with an average particle size of 2 micrometers and 780 parts by mass of spherical alumina powder with an average particle size of 20 micrometers were placed in a V-type mixer for premixing and dried under nitrogen protection and at 110~120℃ for later use. (2) 92.5 parts by mass of polydimethylsiloxane with a viscosity of 50 mPa•s and 5.8 parts by mass of star-shaped polysiloxane prepared in Example 2 were placed in a mixer with a heating jacket and dispersed for 15-30 min under nitrogen protection. Then, 1300 parts by mass of thermally conductive filler pretreated in step (1) were added and the material was heated and dispersed at high speed for 30-60 min under nitrogen protection and the material temperature was controlled at 60-90℃. Finally, 0.8 parts by mass of black paste and 8.4 parts by mass of cerium oxide heat stabilizer with an average particle size of 200 nm were added and mixed for 20-30 min to obtain a thermally conductive organosilicon composition.

[0039] Example 10 This embodiment provides a method for preparing a thermally conductive silicone composition, comprising the following steps: (1) Pretreatment of thermally conductive filler: 330 parts by weight of zinc oxide powder with an average particle size of 0.5 micrometers, 330 parts by weight of spherical aluminum powder with an average particle size of 5 micrometers and 330 parts by weight of spherical aluminum powder with an average particle size of 20 micrometers are placed in a V-type mixer for premixing and then dried under nitrogen protection and at 110~120℃ for later use. (2) 81.2 parts by mass of polydimethylsiloxane with a viscosity of 350 mPa•s and 7.92 parts by mass of star-shaped polysiloxane prepared in Example 3 were placed in a mixer with a heating jacket and dispersed for 15-30 min under nitrogen protection. Then, 990 parts by mass of thermally conductive filler pretreated in step (1) were added and the material was heated and dispersed at high speed for 30-60 min under nitrogen protection and the material temperature was controlled at 60-90℃. Finally, 10.8 parts by mass of cerium oxide heat stabilizer with an average particle size of 200 nm were added and mixed for 20-30 min to obtain a thermally conductive organosilicon composition.

[0040] Comparative Example 1 The difference from Example 8 is that the star-shaped polysiloxane in step (2) is replaced with hexadecyltrimethoxysilane, while the other steps and conditions are the same as in Example 8.

[0041] Comparative Example 2 The difference from Example 9 is that the star-shaped polysiloxane in step (2) is replaced with a single-ended alkoxy-terminated polysiloxane with the following structure; the other steps and conditions are the same as in Example 9. .

[0042] Comparative Example 3 The difference from Example 10 is that 7.92 parts by mass of the star-shaped polysiloxane in step (3) are replaced with 15.84 parts by mass of a single-ended alkoxy-terminated polysiloxane with the following structure. All other steps and conditions are the same as in Example 10. .

[0043] Comparative Example 4 The difference from Example 8 is that in step (2), 1300 parts by mass of the thermally conductive filler pretreated in step (1) and 2.2 parts by mass of the star-shaped polysiloxane prepared in Example 1 are first placed into a mixer with a heating jacket. Under nitrogen protection, the temperature is raised and the material temperature is controlled at 60~90℃ and dispersed at high speed for 30~60min. Then, 97.2 parts by mass of polydimethylsiloxane with a viscosity of 100mPa•s is added. Finally, 5.4 parts by mass of cerium oxide heat stabilizer with an average particle size of 200nm is added and the mixture is continued to be mixed for 20~30min to obtain the thermally conductive organosilicon composition.

[0044] The thermally conductive silicone compositions prepared in Examples 8-10 and Comparative Examples 1-4 were subjected to comparative performance tests. Thermal conductivity was tested according to ISO22007-2-2022, thermal resistance according to ASTM D5470-2017, and viscosity according to ASTM D2196-2020. The thermally conductive compositions were coated onto 2mm thick square aluminum sheets (25mm x 25mm) using a screen, with the adhesive layer thickness controlled at (0.13±0.02) mm. High-temperature tests (150±5℃) / 2000h, damp-heat tests (85±2℃ / 85±5%RH) / 2000h), and alternating hot and cold tests (2000 cycles of -40℃ / 80℃ for 0.5h each) were then conducted. The appearance changes of the thermally conductive silicone composition adhesive layer on the aluminum sheet were observed. The test results are shown in Table 1. Table 1 Performance results of thermally conductive silicone compositions

[0045] As can be seen from the results in Table 1, the thermally conductive silicone composition prepared by surface treatment of the thermally conductive filler with the star-shaped polysiloxane of the present invention has a higher thermal conductivity, lower thermal resistance, and lower viscosity compared with the thermally conductive silicone compositions prepared by the prior art using silane coupling agents hexadecyltrimethoxysilane or polysiloxanes with single-ended alkoxy groups (specifically, Example 8 and Comparative Example 1, Example 9 and Comparative Example 2, Example 10 and Comparative Example 3). Furthermore, after high-temperature testing, damp-heat testing, and cold-heat testing, the thermally conductive silicone composition prepared by the present invention exhibits these properties. After the alternating test, the appearance of the thermally conductive composition did not change significantly. However, the thermally conductive organosilicon compositions prepared using silane coupling agents such as hexadecyltrimethoxysilane or polysiloxanes with single-ended alkoxy groups all exhibited failure phenomena such as hardening, cracking, and phase separation. This indicates that the star-shaped polysiloxane of the present invention can improve the dispersibility and compatibility of the filler in the polymer, and improve the bonding ability between the filler and the polymer by forming an interpenetrating network structure with the organic polymer on the filler surface. This enables the thermally conductive composition of the present invention to effectively resist the effects of high temperature, humid heat, and alternating hot and cold temperatures.

[0046] A comparison of the results of Example 8 and Comparative Example 4 shows that Example 8, by premixing the star-shaped polysiloxane with the organic polymer, causes the molecular chains of the two to become entangled during the mixing process. When subsequently mixed with the thermally conductive filler, the alkoxy groups at the ends of the star-shaped polysiloxane molecular chains undergo a condensation reaction with the hydroxyl groups on the filler surface, anchoring itself to the filler particles. Since the star-shaped polysiloxane has already become entangled with the organic polymer molecular chains, this anchoring effect simultaneously anchors the organic polymer molecular chains to the filler surface. This process is not a simple physical adsorption, but rather uses the star-shaped polysiloxane as a bridge, through the chemical bonding at the ends of its molecular chains and the physical entanglement of the molecular chains, to firmly connect the organic polymer molecules to the filler, forming an interpenetrating network structure. This strong bonding force enables the thermally conductive composition of the present invention to effectively resist high temperature, humid heat, and alternating hot and cold temperatures, preventing phase separation, cracking, powdering, or hardening failures, thereby maintaining the integrity of the interface. In contrast, Comparative Example 4 first mixes the thermally conductive filler with the star-shaped polysiloxane, and then adds the organic polysiloxane. At this point, the star-shaped polysiloxane can still be anchored to the filler particles through condensation reaction. However, because it fails to pre-entangle with the organopolysiloxane molecular chains, it cannot act as a bridge to fix the organic polymer to the filler surface. The organopolysiloxane is only loosely coated on the treated filler surface by physical adsorption, failing to form an effective interpenetrating network. This weak interfacial bonding leads to increased thermal resistance and viscosity of the resulting thermally conductive composition. In damp heat and alternating hot and cold heat tests, the physical adsorption layer is easily destroyed, causing the polymer to desorb from the filler surface and resulting in phase separation.

[0047] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A thermally conductive organosilicon composition, characterized in that, The thermally conductive silicone composition comprises 80-100 parts by weight of organopolysiloxane, 800-1500 parts by weight of thermally conductive filler, and 2-10 parts by weight of star-shaped polysiloxane. The star-shaped polysiloxane has the following structural formula (I): Equation (I); where a and b are 0, 1, or 2; R a Selected from any one of methyl, ethyl, isopropyl, tert-butyl, octyl, dodecyl, octadecyl, and phenyl; R b 'Selected from any one of ethylenetrimethoxysilyl, ethylenetriethoxysilyl, ethylenetrimethoxyethoxysilyl, ethylenetriisopropoxysilyl, propylenetrimethoxysilyl, propylenetriethoxysilyl, propylenetrimethoxyethoxysilyl, and propylenetriisopropoxysilyl; X is selected from the following structural formula (II): Formula (II); n is a positive integer from 3 to 100; Y is a hydrocarbon group with 6 or fewer carbon atoms; R1 and R2 are methyl, vinyl, 2,3-epoxypropoxypropyl, trifluoropropyl or phenyl; R3 is methyl; R4 is methyl or ethyl.

2. The thermally conductive organosilicon composition according to claim 1, characterized in that, The star-shaped polysiloxane is selected from the following compounds 1-7: Compound 1: , Compound 2: , Compound 3: , Compound 4: , Compound 5: , Compound 6: , Compound 7: .

3. The thermally conductive silicone composition according to claim 1, characterized in that, The method for preparing the star-shaped polysiloxane includes the following steps: S1: The cyclic organosiloxane monomer is dissolved in an organic solvent and subjected to a ring-opening polymerization reaction with the organosilane alkoxide in an ice-water bath under an inert atmosphere. After the reaction is completed, chlorosilane is added to carry out a bridging reaction. After the reaction is completed, the target intermediate is obtained by de-molecularization, impurity removal and drying. S2: The target intermediate is subjected to a hydrosilylation reaction with an organosilane to prepare the star-shaped polysiloxane.

4. The thermally conductive silicone composition according to claim 3, characterized in that, In step S1, the cyclic organosiloxane monomer is selected from hexamethylcyclotrisiloxane, 2,4,6-trimethyl-2,4,6-trivinylcyclotrisiloxane, 2,4,6-trimethyl-2,4,6-triphenylcyclotrisiloxane, 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane, hexaphenylcyclotrisiloxane, octamethylcyclotetrasiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetraphenylcyclotetrasiloxane, 2,4,6,8-tetramethyl-2 4,6,8-Tetra(propylglycidyl ether)cyclotetrasiloxane, octaphenylcyclotetrasiloxane, decamethylcyclopentasiloxane; wherein the chlorosilane is selected from at least one of tetrachlorosilane, methyltrichlorosilane, ethyltrichlorosilane, vinyltrichlorosilane, phenyltrichlorosilane, phenethyltrichlorosilane, allyltrichlorosilane, octyltrichlorosilane, dodecyltrichlorosilane, octadecyltrichlorosilane, dimethyldichlorosilane, diethyldichlorosilane, diisopropyldichlorosilane, di-tert-butyldichlorosilane, dioctyldichlorosilane, diphenyldichlorosilane, methylvinyldichlorosilane, and methylallyldichlorosilane.

5. The thermally conductive silicone composition according to claim 3, characterized in that, In step S1, the organosilanes have the following structural formula (III): Formula (III); Wherein, R3 is methyl, vinyl, 2,3-epoxypropoxypropyl, trifluoropropyl or phenyl; R5 is selected from vinyl or allyl; M is sodium or potassium.

6. The thermally conductive silicone composition according to claim 3, characterized in that, In step S2, the organosilane is selected from at least one of trimethoxysilane, triethoxysilane, trimethoxyethoxysilane, and triisopropoxysilane.

7. The thermally conductive silicone composition according to claim 1, characterized in that, The thermally conductive filler includes at least two fillers with different particle sizes; wherein the filler is at least one of metal, metal oxide, metal nitride and carbon-containing material; preferably, the filler is at least one of aluminum, silver, copper, zinc oxide, aluminum oxide, aluminum hydroxide, magnesium oxide, magnesium hydroxide, titanium dioxide, zirconium dioxide, silicon dioxide, aluminum nitride, boron nitride, silicon nitride, silicon carbide, diamond, graphite, carbon fiber, carbon nanotubes and graphene; the average particle size of the thermally conductive filler is 0.01-20 μm.

8. The thermally conductive silicone composition according to claim 1, characterized in that, The thermally conductive organosilicon composition further includes a heat stabilizer with an average particle size of 10-500 nm; wherein the heat stabilizer is selected from any one of cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide.

9. The method for preparing the thermally conductive organosilicon composition according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Premix fillers of different particle sizes and dry them at 110~120℃ under nitrogen protection to obtain pretreated thermally conductive fillers; (2) Disperse the organopolysiloxane and star-shaped polysiloxane under nitrogen protection for 15-30 min; Then, the pretreated thermally conductive filler is added, and the mixture is heated to 60-90°C and dispersed for 30-60 minutes under nitrogen protection. Finally, the heat stabilizer is added and mixed for 20-30 minutes to prepare the thermally conductive organosilicon composition.

10. The use of the thermally conductive silicone composition according to any one of claims 1-8 in thermal interface materials.

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