Heat-conducting filler for low-specific-gravity gel and application of heat-conducting filler
By optimizing the compounding and surface modification of silicon micropowder, calcium carbonate and aluminum hydroxide, a low-specific-gravity, high-insulation thermal conductive filler is prepared, which solves the problems of high cost, high density and poor insulation performance of thermal conductive gel. It is suitable for aerospace, automotive electronics and portable electronic devices.
Patent Information
- Application Number
- CN202510958498.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-11
- Publication Date
- 2025-09-19
AI Technical Summary
The filler materials of existing thermal conductive gels are high in cost, high in density and have poor electrical insulation properties, which limits their application in lightweight electronic devices.
By using low-density silicon micropowder, calcium carbonate and aluminum hydroxide materials, optimizing the particle size compounding and surface modification process, combining silane coupling agent and methyl silicone oil, a low-density, high-insulation thermal conductive filler is prepared to replace high-density zinc oxide as a thixotropic agent.
A low-cost, low-density, and high-insulation thermal conductive gel has been achieved, which improves the insulation protection capability of electronic equipment and reduces the risk of short circuits.
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Figure CN120665348A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of thermal conductive gels, in particular to a thermal conductive filler for low specific gravity gels and applications thereof. Background Art
[0002] Thermally conductive fillers for low-density gels are the main materials for making lightweight gels. They are made of aluminum hydroxide, silicon micropowder, and calcium carbonate as the main raw materials, and are modified by encapsulating with silane coupling agents and methyl silicone oil additives. They have the characteristics of low cost, low specific gravity, and easy filling. The filler material is stirred, mixed, and packaged with vinyl silicone oil to form a gel-like thermal conductive material, which is widely used in aerospace, automotive electronic thermal conductive modules, portable electronic equipment and other fields.
[0003] The lightweight thermal conductive fillers for gels currently on the market have the following problems in practical applications:
[0004] High cost. The current mainstream filler materials for thermal conductive gels include aluminum hydroxide (Al(OH)3), aluminum oxide (Al2O3), boron nitride (BN), zinc oxide (ZnO), etc. Although these materials have excellent thermal conductivity, their cost is relatively high.
[0005] High density. Existing thermal conductive gel fillers generally use aluminum oxide (density 3.95g / cm3) and zinc oxide (density 5.6g / cm3) as the main fillers. However, due to their high density, they have certain limitations in use in lightweight electronic equipment.
[0006] Poor electrical insulation performance. Existing thermal conductive gels have poor electrical insulation performance and can withstand a small breakdown voltage. They cannot provide good insulation protection for electronic components and are prone to short circuits due to excessive current or voltage. Summary of the Invention
[0007] The purpose of the present invention is to provide a thermally conductive filler for low specific gravity gel and a preparation method thereof to solve the problems mentioned in the background technology.
[0008] In order to achieve the above object, the present invention provides the following technical solutions:
[0009] A thermally conductive filler for low specific gravity gel, the mass fraction ratio is as follows:
[0010]
[0011] in,
[0012] The conductivity of silicon powder is ≤100μS / cm and the pH value is 8-10;
[0013] The conductivity of aluminum hydroxide with a particle size of 40-60 microns is ≤100μS / cm and the pH value is 7-9;
[0014] The conductivity of aluminum hydroxide with a particle size of 5-10 microns is ≤100μS / cm and the pH value is 7-9;
[0015] The median particle size of calcium carbonate is 1-5 microns, the conductivity value is ≤100μS / cm, and the pH value is 8-10;
[0016] The silane coupling agent is an alkyl silane coupling agent with a molecular formula of RSiX3, where R represents an organic functional group and X represents a hydrolyzable group;
[0017] The viscosity of methyl silicone oil is 50-300 mPa·s.
[0018] The production process is as follows:
[0019] Step 1: Add silicon micropowder, calcium carbonate, aluminum hydroxide with a particle size of 40-60 microns, and aluminum hydroxide with a particle size of 5-10 microns into a high-speed mixer according to a certain proportion, and stir at a frequency of 40 Hz for 2 minutes to mix the powders evenly to obtain a powder mixture;
[0020] Step 2: Mix the silane coupling agent and methyl silicone oil in a ratio of 2:1 to form an additive;
[0021] Step 3: Add the additives into a high-speed mixer and mix with the powder mixed material. Stir at a frequency of 40 Hz for 5-10 minutes to obtain a thermal conductive filler for low specific gravity gel.
[0022] Application solution 1:
[0023] A thermally conductive gel uses the above-mentioned thermally conductive filler for low-specific-gravity gel, and the mass fraction ratio is as follows:
[0024] 500 parts of thermally conductive filler for low specific gravity gel;
[0025] 100 parts of 500mPa.s vinyl silicone oil.
[0026] The proportion of the thermally conductive filler for low specific gravity gel in this solution is as follows:
[0027]
[0028] The processing technology is as follows:
[0029] Add the thermal conductive filler and 500mPa.s vinyl silicone oil into a stirring device, stir them at a temperature of 100°C and a stirring speed of 10r / min-50r / min for 0.5-3h. During the stirring period, the device must be in a vacuum state to obtain the thermal conductive gel.
[0030] Application solution 2:
[0031] A thermally conductive gel uses the above-mentioned thermally conductive filler for low-specific-gravity gel, and the mass fraction ratio is as follows:
[0032] 300-600 parts of thermal conductive filler for low specific gravity gel;
[0033] 100 parts of 500-1000mPa.s vinyl silicone oil.
[0034] The processing technology is as follows:
[0035] Take 300 / 450 / 600 parts of low-density gel thermal conductive filler and 100 parts of 500mPa.s vinyl silicone oil by mass respectively, place them in a stirring device, and stir them at a temperature of 100°C at a stirring speed of 10r / min-50r / min for 0.5-3h. During the stirring period, the equipment must be in a vacuum state to obtain thermal conductive gels with different filling rates.
[0036] Application plan three:
[0037] A thermally conductive gasket adopts the above-mentioned low-specific-gravity gel thermally conductive filler, and the mass fraction ratio is as follows:
[0038] 100 parts of 500-1000mPa.s vinyl silicone oil;
[0039] 3.5 parts of methyl silicone oil;
[0040] 1 part platinum catalyst
[0041] 0.5 parts of inhibitor;
[0042] 300-600 parts of thermal conductive filler for low specific gravity gel.
[0043] The processing technology is as follows:
[0044] Take 300 / 450 / 600 parts of low-density gel thermal conductive filler, 100 parts of 500mPa.s vinyl silicone oil, 3.5 parts of methyl silicone oil, 1 part of platinum catalyst, and 0.5 part of inhibitor in proportion by mass and place them in a stirring device. Stir at a speed of 10r / min-50r / min at room temperature for 5-10min. The equipment must be in a vacuum state during stirring. Press the obtained rubber material into 1mm thin sheets and bake them at 125° for 30-60min to obtain thermal conductive gaskets with different filling rates.
[0045] The beneficial effects of the present invention are:
[0046] This design uses low-cost, low-specific-gravity, high-insulation silica powder, calcium carbonate, aluminum hydroxide and other materials, and uses calcium carbonate to replace zinc oxide as a thixotropic agent for the filler. By optimizing the compounding ratio of silica powders of different particle sizes, aluminum hydroxide and calcium carbonate, and combining it with a surface modification process, it has a lower oil absorption value and better filling performance in the silica gel system, which can effectively solve the problems of current thermal conductive gel products in terms of cost, density and insulation performance. BRIEF DESCRIPTION OF THE DRAWINGS
[0047] Figure 1 This is a graph showing the thermal conductivity test results of gel samples with different filling rates in the second application scheme of the present invention;
[0048] Figure 2 This is a graph showing the results of extrusion performance testing of gel samples with different filling rates in the second application scheme of the present invention;
[0049] Figure 3 This is a graph showing the test results of the gasket electrical insulation performance of sheets with different filling rates in the third application scheme of the present invention. DETAILED DESCRIPTION
[0050] The present invention will be further described below with reference to the accompanying drawings:
[0051] A thermally conductive filler for low specific gravity gel, the mass fraction ratio is as follows:
[0052]
[0053]
[0054] in,
[0055] The conductivity of silicon powder is ≤100μS / cm and the pH value is 8-10;
[0056] The conductivity of aluminum hydroxide with a particle size of 40-60 microns is ≤100μS / cm and the pH value is 7-9;
[0057] The conductivity of aluminum hydroxide with a particle size of 5-10 microns is ≤100μS / cm and the pH value is 7-9;
[0058] The median particle size of calcium carbonate is 1-5 microns, the conductivity value is ≤100μS / cm, and the pH value is 8-10;
[0059] The silane coupling agent is an alkyl silane coupling agent with the molecular formula RSiX3, where R represents an organic functional group and X represents a hydrolyzable group. The silane coupling agent can link inorganic materials and organic compounds, forming stable chemical bonds with the hydroxyl groups on the surface of inorganic materials and interacting with the long molecular chains in organic polymers.
[0060] The viscosity of methyl silicone oil is 50-300mPa·s. The decomposition temperature of methyl silicone oil begins at 250℃ and the complete decomposition temperature is 550℃.
[0061] The production process is as follows:
[0062] Step 1: Add silicon micropowder, calcium carbonate, aluminum hydroxide with a particle size of 40-60 microns, and aluminum hydroxide with a particle size of 5-10 microns into a high-speed mixer according to a certain proportion, and stir at a frequency of 40 Hz for 2 minutes to mix the powders evenly to obtain a powder mixture;
[0063] Step 2: Mix the silane coupling agent and methyl silicone oil in a ratio of 2:1 to form an additive;
[0064] Step 3: Add the additives into a high-speed mixer and mix with the powder mixed material. Stir at a frequency of 40 Hz for 5-10 minutes to obtain a thermal conductive filler for low specific gravity gel.
[0065] This design uses low-cost, low-specific-gravity, high-insulation silica powder, calcium carbonate, aluminum hydroxide and other materials, and uses calcium carbonate to replace zinc oxide as a thixotropic agent for the filler. By optimizing the compounding ratio of silica powders of different particle sizes, aluminum hydroxide and calcium carbonate, and combining it with a surface modification process, it has a lower oil absorption value and better filling performance in the silica gel system, which can effectively solve the problems of current thermal conductive gel products in terms of cost, density and insulation performance.
[0066] Application solution 1:
[0067] A thermally conductive gel uses the above-mentioned thermally conductive filler for low-specific-gravity gel, and the mass fraction ratio is as follows:
[0068] 500 parts of thermally conductive filler for low specific gravity gel;
[0069] 100 parts of 500mPa.s vinyl silicone oil.
[0070] The proportion of the thermally conductive filler for low specific gravity gel in this solution is as follows:
[0071]
[0072] The viscosity of the silane coupling agent is 10 mPa·s, and the viscosity of the methyl silicone oil is 100 mPa·s.
[0073] The preparation test was carried out according to the above scheme, and compared with the other four comparative examples. The specific scheme is shown in the following table:
[0074]
[0075]
[0076] The fillers obtained by the above schemes are processed by the following processing techniques:
[0077] Add 500 parts of thermal conductive filler and 100 parts of 500mPa.s vinyl silicone oil into a stirring device, stir at a temperature of 100°C and a stirring speed of 10r / min-50r / min for 0.5-3h. During the stirring period, the device must be in a vacuum state to obtain a thermal conductive gel.
[0078] The thermal conductive gel products obtained in Example and Comparative Examples 1-4 were subjected to performance tests, and the specific performance data are shown in the following table:
[0079]
[0080] As can be seen from the above table, (1) the overall effect of the embodiment is consistent with the product performance, and the comprehensive performance is better than other implementation cases;
[0081] Comparative Example 1: In contrast to the embodiment, methyl silicone oil was not used to coat the powder, and there was no high-temperature resistant additive to protect the powder. The high-temperature resistance was poor, and the powder hardened after the reliability test.
[0082] Comparative Example 2: In contrast to the embodiment, no silane coupling agent was used to coat the powder. A stable chemical bond could not be formed between the powder and the organic matter, resulting in poor powder absorption. The resulting gel was semi-fluid, had low thermal conductivity, high viscosity, poor extrusion performance, and little change in reliability before and after.
[0083] Comparative Example 3 Compared with the embodiment, the filling amount of silicon powder was increased, which reduced the thermal conductivity, increased the viscosity, and had poor extrusion performance. The reliability performance did not change much before and after.
[0084] Comparative Example 4: Compared with the embodiment, the filling amount of calcium carbonate was reduced, and no calcium carbonate was used as a thixotropic agent. The gel produced was semi-fluid, which did not meet the requirements. The other properties were good, and the reliability did not change much before and after.
[0085] In summary, the performance of this embodiment is the best.
[0086] Application solution 2:
[0087] A thermally conductive gel uses the above-mentioned thermally conductive filler for low-specific-gravity gel, and the mass fraction ratio is as follows:
[0088] 300-600 parts of thermal conductive filler for low specific gravity gel;
[0089] 100 parts of 500-1000mPa.s vinyl silicone oil.
[0090] The processing technology is as follows:
[0091] Take 300 / 450 / 600 parts of low-density gel thermal conductive filler and 100 parts of 500mPa.s vinyl silicone oil by mass respectively, place them in a stirring device, and stir them at a temperature of 100°C at a stirring speed of 10r / min-50r / min for 0.5-3h. During the stirring period, the equipment must be in a vacuum state to obtain thermal conductive gels with different filling rates.
[0092] The thermal conductivity of gel samples with different filling rates was tested using thermal conductivity testing equipment. The test results are as follows: Figure 1 shown.
[0093] The extrusion performance of gel samples with different filling rates was tested using an automatic dispensing machine. The test results are as follows: Figure 2 shown.
[0094] The thermal conductivity test was conducted using a thermal conductivity meter with a steady-state heat flow method, at an end surface temperature of 65° C. and an applied pressure of 50 N. The test was conducted in accordance with the thermal conductivity test method ASTM-5470.
[0095] The extrusion performance test was conducted by using an automatic dispensing machine to fill the rubber into a 30cc syringe, applying a pressure of 90 Psi, and setting the test time to 1 minute.
[0096] In summary, the higher the filling rate of thermally conductive filler for low-density gel, the higher the thermal conductivity coefficient and the lower the extrusion performance. In actual application, the appropriate filling rate should be selected according to the required performance of the product.
[0097] Application plan three:
[0098] A thermally conductive gasket adopts the above-mentioned low-specific-gravity gel thermally conductive filler, and the mass fraction ratio is as follows:
[0099] 100 parts of 500-1000mPa.s vinyl silicone oil;
[0100] 3.5 parts of methyl silicone oil;
[0101] 1 part platinum catalyst
[0102] 300-600 parts of thermal conductive filler for low specific gravity gel.
[0103] The processing technology is as follows:
[0104] Take 300 / 450 / 600 parts of low-density gel thermal conductive filler, 100 parts of 500mPa.s vinyl silicone oil, 3.5 parts of methyl silicone oil, 1 part of platinum catalyst, and 0.5 part of inhibitor in proportion by mass and place them in a stirring device. Stir at a speed of 10r / min-50r / min at room temperature for 5-10min. The equipment must be in a vacuum state during stirring. Press the obtained rubber material into 1mm thin sheets and bake them at 125° for 30-60min to obtain thermal conductive gaskets with different filling rates.
[0105] The gasket electrical insulation performance of the prepared sheets with different filling rates was tested using a breakdown voltage tester. The test results are as follows: Figure 3 shown.
[0106] The above electrical insulation performance test: use a breakdown voltage tester, set AC power, set the voltage rise rate to 0.5KV / s, input the actual thickness of the sheet to start the test, and the test will obtain the voltage intensity data when the sheet is just broken down.
[0107] The larger the breakdown voltage is, the better the electrical insulation performance of the material is, and vice versa.
[0108] like Figure 3 As shown, the material's electrical insulation performance is significantly negatively correlated with the filler filling ratio, meaning the lower the filling ratio, the better the electrical insulation performance. However, even at a high filling ratio of 1:6, the material still exhibits excellent dielectric properties, with a breakdown strength of 16.7kV / mm, a value that exceeds the performance level of currently available mainstream thermal conductive gel products.
[0109] The above description does not limit the technical scope of the present invention. Any modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.
Claims
1. A thermally conductive filler for low specific gravity gel, characterized by: The proportions by mass fraction are as follows:
2. The thermally conductive filler for low-specific-gravity gel according to claim 1, characterized in that: The conductivity of silicon powder is ≤100μS / cm and the pH value is 8-10; Aluminum hydroxide with a particle size of 40-60 microns has a conductivity value of ≤100μS / cm and a pH value of 7-9; The conductivity of aluminum hydroxide with a particle size of 5-10 microns is ≤100μS / cm and the pH value is 7-9; The conductivity of calcium carbonate is ≤100μS / cm and the pH value is 8-10; The silane coupling agent is an alkyl silane coupling agent with a molecular formula of RSiX3, where R represents an organic functional group and X represents a hydrolyzable group; The viscosity of methyl silicone oil is 50-300 mPa·s.
3. The thermally conductive filler for low-specific-gravity gel according to claim 1, characterized in that: The production process is as follows: Step 1: Add silicon micropowder, calcium carbonate, aluminum hydroxide with a particle size of 40-60 microns, and aluminum hydroxide with a particle size of 5-10 microns into a high-speed mixer according to a certain proportion, and stir at a frequency of 40 Hz for 2 minutes to mix the powders evenly to obtain a powder mixture; Step 2: Mix the silane coupling agent and methyl silicone oil in a ratio of 2:1 to form an additive; Step 3: Add the additives into a high-speed mixer and mix with the powder mixed material. Stir at a frequency of 40 Hz for 5-10 minutes to obtain a thermal conductive filler for low specific gravity gel.
4. A thermally conductive gel, characterized in that: The low-density gel thermal conductive filler according to any one of claims 1 to 3 is used, and the mass fraction ratio is as follows: 500 parts of thermally conductive filler for low specific gravity gel; 100 parts of 500mPa.s vinyl silicone oil.
5. The thermally conductive gel according to claim 4, characterized in that: The proportion of ingredients in the thermal conductive filler for low specific gravity gel is as follows:
6. The thermally conductive gel according to claim 4, characterized in that: The processing technology is as follows: Add the thermal conductive filler and 500mPa.s vinyl silicone oil into a stirring device, stir them at a temperature of 100°C and a stirring speed of 10r / min-50r / min for 0.5-3h. During the stirring period, the device must be in a vacuum state to obtain the thermal conductive gel.
7. A thermally conductive gel, characterized in that: The low-density gel thermal conductive filler according to any one of claims 1 to 3 is used, and the mass fraction ratio is as follows: 300-600 parts of thermal conductive filler for low specific gravity gel; 100 parts of 500-1000mPa.s vinyl silicone oil.
8. The thermally conductive gel according to claim 7, characterized in that: The processing technology is as follows: Take 300 / 450 / 600 parts of low-density gel thermal conductive filler and 100 parts of 500mPa.s vinyl silicone oil by mass respectively, place them in a stirring device, and stir them at a temperature of 100°C at a stirring speed of 10r / min-50r / min for 0.5-3h. During the stirring period, the equipment must be in a vacuum state to obtain thermal conductive gels with different filling rates.
9. A thermally conductive gasket, characterized in that: The low-density gel thermal conductive filler according to any one of claims 1 to 3 is used, and the mass fraction ratio is as follows:
10. The thermally conductive gasket according to claim 9, characterized in that: The processing technology is as follows: take 300 / 450 / 600 parts of low-density gel thermal conductive filler, 100 parts of 500mPa.s vinyl silicone oil, 3.5 parts of methyl silicone oil, 1 part of platinum catalyst, and 0.5 parts of inhibitor in proportion by mass and place them in a stirring device. Stir at a speed of 10r / min-50r / min at room temperature for 5-10 minutes. The equipment must be in a vacuum state during stirring. Press the obtained rubber into 1mm thin sheets and bake them at 125° for 30-60 minutes to obtain thermal conductive gaskets with different filling rates.