Low volatile silicone thermal pad and method of making same
By using high-temperature, high-vacuum distillation purification and dehydration agent treatment, combined with the calendering molding of platinum catalyst, low-volatile organosilicon thermal pads are prepared. This solves the problem of volatile substances from organosilicon thermal pads contaminating optical components at high temperatures, achieving long-term optical clarity and equipment stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHENZHEN AOCHUAN TECH CO LTD
- Filing Date
- 2026-06-02
- Publication Date
- 2026-07-31
AI Technical Summary
Existing silicone thermal pads, in applications requiring high optical precision, cause volatile small molecules and water molecules to contaminate optical components, leading to decreased light transmittance and blurred imaging. Current technologies are unable to effectively suppress the effects of volatilization and water molecules.
The silicone oil components were purified by high-temperature and high-vacuum distillation to remove small molecule volatiles. Water molecules were removed by mixing and stirring a dehydrating agent with a thermally conductive filler and then heating by friction. The mixture was then calendered and vulcanized at high temperature using a platinum catalyst to produce a low-volatility silicone thermally conductive pad.
It achieves long-term stability and low volatility at high temperatures, ensuring the clarity of optically transparent components and improving the accuracy and lifespan of electronic devices.
Smart Images
Figure CN122483579A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electronic materials technology, specifically to a low-volatile organosilicon thermal pad and its preparation method. Background Technology
[0002] Silicone thermal pads are widely used to fill the gaps between heat-generating components and heat sinks due to their excellent flexibility and thermal conductivity, achieving efficient heat transfer. However, in applications requiring extremely high optical precision, such as optical modules, cameras, LiDAR, and lighting components, ordinary silicone thermal pads release small molecules during use (mainly from unreacted silicone oil oligomers or catalyst residues). These small molecules gradually accumulate and condense on the surface of transparent optical components such as glass and lenses in a confined space, leading to decreased light transmittance and blurred images, severely affecting the accuracy and lifespan of electronic devices.
[0003] Existing technologies typically attempt to reduce volatile content by increasing raw material purity or extending post-curing time, but these methods are still insufficient to meet the stringent low-volatility requirements of the optical module field. In-depth analysis reveals that the main factors affecting the low-volatility performance of thermal pads are the residual small-molecule volatiles in the silicone matrix (such as vinyl silicone oil, hydrogen-containing silicone oil, etc.) and water molecules adsorbed on and within the surface of the thermally conductive filler. Under high-temperature operating conditions, water molecule vaporization can also form mist, causing contamination and blurring of optical components. Existing technologies often overlook the crucial impact of moisture in the thermally conductive filler.
[0004] Therefore, there is an urgent need for a low-volatility silicone thermal pad that can suppress the volatilization of organic matter and moisture and has long-term stability, as well as its preparation method. Summary of the Invention
[0005] In view of the aforementioned problems, this application is made to provide a low-volatile silicone thermal pad and a method for preparing the same, which overcomes or at least partially solves the aforementioned problems, comprising: A method for preparing a low-volatile silicone thermal pad includes the following steps: The thermally conductive filler (without moisture), vinyl silicone oil (without volatiles), hydrogen-containing silicone oil (without volatiles), dimethyl silicone oil (without volatiles), and alkynyl alcohol inhibitor are mixed in a specified mass ratio under the first specified conditions to obtain mixed rubber compound A. The mixed adhesive A and the platinum catalyst were vacuum stirred and mixed under a second specified condition to obtain mixed adhesive B; The mixed rubber compound B is calendered and vulcanized at high temperature under a third specified condition to obtain the low-volatile silicone thermal pad of a specified thickness.
[0006] Furthermore, the thermally conductive filler is composed of a first-stage thermally conductive filler, a second-stage thermally conductive filler, and a third-stage thermally conductive filler mixed in a mass ratio of 6:2:2. The first-stage thermally conductive filler is one of aluminum hydroxide, angular alumina, near-spherical alumina, or spherical alumina, with a median particle size of 40 μm to 70 μm; The second-stage thermally conductive filler is one of angular alumina, near-spherical alumina, or spherical alumina, with a median particle size of 5 μm to 7 μm; The third-stage thermally conductive filler is one of angular alumina, quasi-spherical alumina, or spherical alumina, with a median particle size of 1 μm to 3 μm.
[0007] Furthermore, the method also includes: The thermally conductive filler and the dehydrating agent are mixed and stirred in a high-speed mixer, and the temperature is raised to 75°C to 90°C by friction to obtain the dehydrated thermally conductive filler. Vinyl silicone oil, hydrogen-containing silicone oil, and dimethyl silicone oil were purified by vacuum distillation under the fourth specified conditions to obtain vinyl silicone oil, hydrogen-containing silicone oil, and dimethyl silicone oil after removing volatile components.
[0008] Furthermore, the dehydrating agent is dimethyldimethoxysilane, and the amount of the dehydrating agent added is 0.05% to 0.3% of the total mass of the thermally conductive filler.
[0009] Furthermore, the fourth specified condition is a temperature of 180℃~230℃, a vacuum degree of -0.09MPa~-0.1MPa, and a processing time of 0.5~2 hours.
[0010] Furthermore, the vinyl silicone oil excluding volatile components is a double-ended vinyl silicone oil with a vinyl content of 0.4% to 0.6% and a viscosity of 400 cP to 600 cP; The hydrogen-containing silicone oil, excluding volatile components, is a side-end hydrogen-containing silicone oil with a hydrogen content of 0.09% to 0.11% and a viscosity of 150 cP to 250 cP. The viscosity of the dimethyl silicone oil, excluding volatile components, is 200 cP to 300 cP.
[0011] Furthermore, the alkynol inhibitor is 1-ethynyl-1-cyclohexanol, and the 1-ethynyl-1-cyclohexanol is pre-mixed and diluted with the vinyl silicone oil (excluding volatiles) at a mass ratio of 5:95. The first specified condition is a stirring speed of 10~20 rpm and a stirring time of 20~60 min.
[0012] Furthermore, the platinum catalyst is chloroplatinic acid, and the chloroplatinic acid is pre-mixed and diluted with the vinyl silicone oil (excluding volatiles) to a platinum content of 3000ppm to 5000ppm; The second specified conditions are a stirring speed of 10~35 rpm, a vacuum degree of -0.09~-0.1 MPa, and a stirring time of 30~90 min.
[0013] Furthermore, the third specified condition is a temperature of 100℃~150℃ and a vulcanization time of 10min~30min; the specified thickness is 1~6mm.
[0014] A low-volatility silicone thermal pad is prepared by the following method: 100-500 parts by weight of vinyl silicone oil (excluding volatiles), 3-20 parts by weight of hydrogen-containing silicone oil (excluding volatiles), 1-10 parts by weight of dimethyl silicone oil (excluding volatiles), 400-1500 parts by weight of thermally conductive filler (excluding moisture), 1-5 parts by weight of alkynyl alcohol inhibitor, and 0.5-5 parts by weight of platinum catalyst.
[0015] This application has the following advantages: In the embodiments of this application, addressing the core defects of the prior art, such as the easy release of volatile small molecules from the silicone matrix itself and the neglect of adsorbed water molecules in the thermally conductive filler, leading to volatile contamination of optical components at high temperatures, this application provides a method for preparing a low-volatile silicone thermally conductive pad. Specifically, the method involves mixing a dehydrated thermally conductive filler, a devolatile vinyl silicone oil, a devolatile hydrogen-containing silicone oil, a devolatile dimethyl silicone oil, and an alkynyl alcohol inhibitor under a first specified condition according to a specified mass ratio to obtain a mixed adhesive A; mixing the mixed adhesive A with a platinum catalyst under vacuum under a second specified condition to obtain a mixed adhesive B; and calendering and high-temperature vulcanizing the mixed adhesive B under a third specified condition to obtain the low-volatile silicone thermally conductive pad of a specified thickness. By pre-purifying the silicone oil components through high-temperature, high-vacuum distillation, small-molecule volatiles such as silicone oil oligomers are removed, solving the problem of blurring of optically transparent components caused by the volatilization of organic matter during the use of thermally conductive pads. This achieves the effect of ensuring the long-term optical clarity of precision electronic devices such as optical modules. By mixing and stirring a dehydrating agent with a thermally conductive filler and then frictionally heating it, the dehydrating agent reacts with water molecules in the filler and performs hydrophobic grafting modification on its surface. This removes moisture from the filler and gives it long-term moisture-proof properties, solving the problems of moisture vaporization and fogging at high temperatures in the filler and batch instability caused by moisture absorption in the filler. This achieves the effect of improving the reproducibility and reliability of low-volatility performance. Attached Figure Description
[0016] To more clearly illustrate the technical solution of this application, the drawings used in the description of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0017] Figure 1 This is a flowchart of the steps in a method for preparing a low-volatile silicone thermal pad according to an embodiment of this application; Figure 2 This is a process flow diagram of a method for preparing a low-volatile organosilicon thermal pad according to an embodiment of this application. Detailed Implementation
[0018] To make the objectives, features, and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.
[0019] The inventors, through analysis of existing technologies, discovered that current silicone thermal pads release small organic volatiles during use. These substances easily adhere to the surfaces of transparent optical materials such as glass, causing blurring of optical components and severely reducing equipment accuracy and shortening its lifespan. The volatiles from silicone thermal pads mainly originate from two factors: firstly, residual small volatile molecules in the silicone resin raw material; and secondly, water molecules adsorbed by the thermally conductive filler. The evaporation and condensation of these volatiles within the sealed optical cavity are the primary cause of optical component failure. Current technologies lack a preparation process that simultaneously removes small molecules from the silicone raw material, removes moisture from the thermally conductive filler, and inhibits filler moisture reabsorption, thus failing to produce low-volatile silicone thermal pads suitable for the optical module field.
[0020] Reference Figure 1-2 This application illustrates a method for preparing a low-volatile silicone thermal pad according to an embodiment of the present application, including the following steps: S110. The thermally conductive filler (without moisture), vinyl silicone oil (without volatiles), hydrogen-containing silicone oil (without volatiles), dimethyl silicone oil (without volatiles), and alkynyl alcohol inhibitor are mixed in a specified mass ratio under the first specified conditions to obtain mixed rubber compound A. S120. The mixed adhesive A and the platinum catalyst are mixed under vacuum stirring under a second specified condition to obtain mixed adhesive B. S130. The mixed rubber compound B is calendered and vulcanized at high temperature under the third specified conditions to obtain the low-volatile silicone thermal pad of the specified thickness.
[0021] In the embodiments of this application, by pre-purifying the organosilicon oil components through high-temperature and high-vacuum distillation, small molecule volatiles such as silicone oil oligomers are removed, solving the problem of blurring of optically transparent components caused by the volatilization of organic matter during the use of thermally conductive pads, thus achieving the effect of ensuring the long-term optical clarity of precision electronic devices such as optical modules; by mixing and stirring the dehydrating agent with the thermally conductive filler and frictionally heating it, the dehydrating agent reacts with the water molecules in the filler and performs hydrophobic grafting modification on its surface, removing the moisture in the filler and giving it long-term moisture-proof properties, solving the problems of moisture vaporization of the filler at high temperatures to form mist and batch instability caused by moisture absorption of the filler, thus achieving the effect of improving the reproducibility and reliability of low volatility performance.
[0022] The following will further describe a method for preparing a low-volatile silicone thermal pad in this exemplary embodiment.
[0023] In one embodiment of the present invention, the specific process of step S110, which involves mixing thermally conductive filler (without moisture), vinyl silicone oil (without volatiles), hydrogen-containing silicone oil (without volatiles), dimethyl silicone oil (without volatiles), and alkynyl alcohol inhibitors under a first specified condition according to a specified mass ratio, can be further described in conjunction with the following description to obtain mixed adhesive A.
[0024] In this embodiment, the thermally conductive filler is composed of a first-stage thermally conductive filler, a second-stage thermally conductive filler, and a third-stage thermally conductive filler mixed in a mass ratio of 6:2:2. The first-stage thermally conductive filler is one of aluminum hydroxide, angular alumina, near-spherical alumina, or spherical alumina, with a median particle size of 40 μm to 70 μm; The second-stage thermally conductive filler is one of angular alumina, near-spherical alumina, or spherical alumina, with a median particle size of 5 μm to 7 μm; The third-stage thermally conductive filler is one of angular alumina, quasi-spherical alumina, or spherical alumina, with a median particle size of 1 μm to 3 μm.
[0025] In this embodiment, the vinyl silicone oil excluding volatiles is a double-ended vinyl silicone oil with a vinyl content of 0.4% to 0.6% and a viscosity of 400 cP to 600 cP. The hydrogen-containing silicone oil, excluding volatile components, is a side-end hydrogen-containing silicone oil with a hydrogen content of 0.09% to 0.11% and a viscosity of 150 cP to 250 cP. The viscosity of the dimethyl silicone oil, excluding volatile components, is 200 cP to 300 cP.
[0026] In this embodiment, the alkynol inhibitor is 1-ethynyl-1-cyclohexanol, and the 1-ethynyl-1-cyclohexanol is pre-mixed and diluted with the vinyl silicone oil (excluding volatiles) at a mass ratio of 5:95. The first specified condition is a stirring speed of 10~20 rpm and a stirring time of 20~60 min.
[0027] It should be noted that 1-ethynyl-1-cyclohexanol, an alkynyl alcohol inhibitor, is a solid at room temperature. Direct addition makes it difficult to disperse evenly in the rubber compound, potentially leading to excessively strong or weak local inhibition effects, which can affect the subsequent control of platinum catalyst activity. Pre-mixing and diluting it with vinyl silicone oil (excluding volatiles) at a 5:95 ratio forms a homogeneous and stable liquid inhibitor stock solution, facilitating metering and dispersion without introducing additional small-molecule volatiles. The stirring speed is controlled at 10–20 rpm because too low a speed makes it difficult for the filler and silicone oil to mix thoroughly, potentially leading to localized filler agglomeration or uneven distribution of the crosslinking agent; too high a speed introduces air bubbles and generates shear heat, which may raise the compound temperature and prematurely trigger the crosslinking reaction. A stirring time of 20–60 minutes ensures that the thermally conductive filler with a high filler content is completely wetted by the silicone oil.
[0028] As an example, in a planetary mixer, vinyl silicone oil (excluding volatiles), hydrogen-containing silicone oil, and dimethyl silicone oil are first added according to the formula ratio. The mixer is then started (15 rpm) and mixed for 2 minutes. Next, thermally conductive filler (excluding moisture) is added in three batches, with mixing continuing for 5 minutes after each addition. Finally, an alkynyl alcohol inhibitor mother liquor is added, and mixing continues for another 30 minutes, for a total mixing time of approximately 50 minutes. During the mixing process, the material temperature is observed to be no higher than 40°C, and there is no undispersed dry powder on the barrel wall; at this point, the mixed rubber compound A is considered to have met the requirements. In this example, mixed rubber compound A has a uniform viscosity and no visible white filler particles. The gaskets obtained after subsequent vulcanization with a catalyst exhibit uniform mechanical and thermal conductivity.
[0029] In an additional embodiment of the present invention, the method further includes the step of: The thermally conductive filler and the dehydrating agent are mixed and stirred in a high-speed mixer, and the temperature is raised to 75°C to 90°C by friction to obtain the dehydrated thermally conductive filler. Vinyl silicone oil, hydrogen-containing silicone oil, and dimethyl silicone oil were purified by vacuum distillation under the fourth specified conditions to obtain vinyl silicone oil, hydrogen-containing silicone oil, and dimethyl silicone oil after removing volatile components.
[0030] In this embodiment, the dehydrating agent is dimethyldimethoxysilane, and the amount of the dehydrating agent added is 0.05% to 0.3% of the total mass of the thermally conductive filler.
[0031] In this embodiment, the fourth specified condition is a temperature of 180℃~230℃, a vacuum degree of -0.09MPa~-0.1MPa, and a processing time of 0.5~2 hours.
[0032] It should be noted that thermally conductive fillers will absorb moisture from the air during transportation and storage, with a moisture content typically ranging from 0.1% to 0.5%. Dimethyldimethoxysilane, as a dehydrating agent, utilizes its highly reactive methoxy groups to rapidly react with water molecules to generate silanol and methanol. Simultaneously, the silanol can undergo a grafting reaction with the hydroxyl groups on the filler surface to form a hydrophobic layer, thereby permanently removing moisture and inhibiting subsequent moisture absorption.
[0033] Friction heating to 75℃~90℃ serves two purposes: first, it accelerates reaction kinetics, allowing the dehydrating agent to complete its reaction with water molecules within a certain time; second, it utilizes the low boiling points of methanol and excess dimethyldimethoxysilane (methanol boiling point 64.7℃, dimethyldimethoxysilane boiling point 81.5℃) to allow them to volatilize during stirring, preventing residue. Temperatures below 75℃ result in incomplete reaction and volatilization; temperatures above 90℃ may cause packing agglomeration or increased energy consumption.
[0034] Vacuum distillation purification of silicone oil utilizes the principle that the boiling point of low-molecular-weight cyclosiloxanes (such as D3, D4, D5, etc.) is significantly reduced under high temperature and high vacuum, allowing them to be vaporized and extracted from the silicone oil. At processing temperatures of 180–230℃ and vacuum levels below -0.09 MPa, the partial pressure of small-molecule volatiles is extremely low, and the volatile content can be reduced from 0.5%–1.0% to below 0.05% within 0.5–2 hours.
[0035] As an example, 1000g of compound thermally conductive filler was placed in a 5L high-speed mixer, and 2g of dimethyldimethoxysilane (0.2%) was added. The mixer was then covered and stirred at 800rpm. Due to frictional heat generation, the temperature rose to 82℃ after 15 minutes. At this point, the exhaust port was opened, and stirring continued for 5 minutes. Then, stirring was stopped, and the mixture was cooled to room temperature to obtain the dehydrated thermally conductive filler. Karl Fischer analysis showed that the moisture content before treatment was 0.25%, which decreased to 0.02% after treatment. For silicone oil purification, taking double-ended vinyl silicone oil as an example, it was added to a thin-film evaporator. The temperature was set at 200℃, the vacuum degree at -0.098MPa, the feed rate at 10kg / h, and the treatment time at approximately 1 hour. The treated silicone oil was collected. Gas chromatography analysis showed that the total cyclic content before treatment was 0.8%, which decreased to 0.02% after treatment.
[0036] In one embodiment of the present invention, the specific process of step S120, "mixing the mixed adhesive A with the platinum catalyst under vacuum stirring under a second specified condition to obtain mixed adhesive B," can be further described in conjunction with the following description.
[0037] In this embodiment, the platinum catalyst is chloroplatinic acid, and the chloroplatinic acid is pre-mixed and diluted with the vinyl silicone oil (excluding volatiles) to a platinum content of 3000ppm to 5000ppm. The second specified conditions are a stirring speed of 10~35 rpm, a vacuum degree of -0.09~-0.1 MPa, and a stirring time of 30~90 min.
[0038] It should be noted that chloroplatinic acid is a highly efficient catalyst for addition-type vulcanization systems, but it is a reddish-brown crystal. Directly adding evenly small amounts (ppm level) cannot achieve uniform dispersion, easily leading to excessively fast or slow localized vulcanization rates. Pre-diluting with vinyl silicone oil (with volatiles removed) to a platinum concentration of 3000–5000 ppm creates an easily measurable liquid catalyst stock solution, ensuring uniform dispersion in the rubber compound. A stirring speed of 10–35 rpm is used to avoid generating a large number of bubbles during mixing, while ensuring sufficient contact between the catalyst and the rubber compound. Vacuum mixing (vacuum degree below -0.09 MPa) effectively removes air bubbles and trace gases (such as hydrogen) generated during the mixing process, preventing pores or pinholes inside the vulcanized gasket and also aiding in the further removal of residual small molecules. The stirring time of 30–90 minutes depends on the viscosity of the rubber compound and the efficiency of the equipment. Too short a time results in uneven mixing, while too long a time may lead to decreased catalyst activity or thickening of the rubber compound.
[0039] As an example, after the preparation of compound A, a platinum catalyst mother liquor (e.g., platinum content 4000 ppm) is added to the planetary mixer. The mixing tank is closed, and the vacuum pump is turned on. Once the vacuum reaches -0.095 MPa, stirring is started at 25 rpm. During stirring, the material state is carefully observed. If the material temperature exceeds 45°C, cooling water should be circulated appropriately to lower the temperature. After stirring for 45 minutes, the vacuum is turned off, and the observation port is opened to check whether the compound is bright and free of bubbles. If bubbles still remain on the surface of the compound, the vacuum stirring time can be extended to 60 minutes. After meeting the requirements, the material is discharged to obtain compound B, which should be calendered and vulcanized within 8 hours to avoid slow crosslinking at room temperature, which would lead to a decrease in fluidity.
[0040] In one embodiment of the present invention, the specific process of step S130, "calendering and high-temperature vulcanizing the mixed rubber compound B under a third specified condition to obtain the low-volatile silicone thermal conductive pad of a specified thickness," can be further described in conjunction with the following description.
[0041] In this embodiment, the third specified condition is a temperature of 100℃~150℃ and a vulcanization time of 10min~30min; the specified thickness is 1~6mm.
[0042] It is important to note that calendering and high-temperature vulcanization are crucial steps in forming the final shape of the thermal pad and completing cross-linking. The choice of temperature needs to balance vulcanization efficiency and the complete elimination of small-molecule volatiles. At temperatures too low (<100℃), the vulcanization speed is slow, cross-linking is incomplete, and residual vinyl or silane groups may continue to react and release small molecules during later use; simultaneously, the viscosity of the rubber compound is high at low temperatures, resulting in uneven calendering thickness. At temperatures too high (>150℃), it may lead to oxidative degradation of the silicone oil or decomposition of the filler surface treatment agent, which in turn increases volatiles. The vulcanization time must be matched with the temperature: 30 minutes at 100℃ and only 10 minutes at 150℃ for complete vulcanization. Thicknesses of 1–6 mm cover commonly used pad specifications in the optical module field. During the calendering process, the linear speed and gap of the calendering rollers should also be controlled to ensure a thickness tolerance within ±0.1 mm.
[0043] As an example, taking the preparation of a 2mm thick gasket as an example: Mixed rubber compound B is placed into the hopper of a three-roll calender. The gap and speed of the upper, middle, and lower rollers are adjusted to produce a sheet thickness of 2.0 ± 0.05mm. The calendered sheet, along with the release film, enters a three-stage tunnel vulcanizing furnace: the first stage is at 110℃ for 8 minutes to preheat the rubber compound and allow residual trace volatiles to escape; the second stage is at 130℃ for 8 minutes for primary vulcanization; and the third stage is at 150℃ for 4 minutes for complete cross-linking. The total vulcanization time is 20 minutes. After vulcanization, the gasket is naturally cooled to room temperature and cut into the desired shape to obtain a low-volatile silicone thermal conductive gasket. Testing shows that the volatile content (150℃ × 24h) of this gasket is less than 0.1%, and the compression set is less than 5%.
[0044] One embodiment of the present invention provides a low-volatility silicone thermal pad, which is prepared from 100 to 500 parts by weight of vinyl silicone oil (excluding volatiles), 3 to 20 parts by weight of hydrogen-containing silicone oil (excluding volatiles), 1 to 10 parts by weight of dimethyl silicone oil (excluding volatiles), 400 to 1500 parts by weight of thermally conductive filler (excluding moisture), 1 to 5 parts by weight of alkynyl alcohol inhibitor, and 0.5 to 5 parts by weight of platinum catalyst.
[0045] The thermally conductive pad and its preparation method of the present invention will be described in detail below with reference to specific embodiments.
[0046] Example 1: S1: 600 parts of aluminum hydroxide with a median particle size of 60μm in the first-stage thermally conductive filler, 200 parts of angular alumina with a median particle size of 7μm in the second-stage thermally conductive filler, and 200 parts of angular alumina with a median particle size of 3μm in the third-stage thermally conductive filler are stirred in a high-speed mixer at 500rpm for 3min to obtain a compound thermally conductive filler. S2: The compound thermally conductive filler obtained in S1 is mixed with 0.2% of the dehydrating agent by mass in a high-speed mixer at 500 rpm for 20 minutes and heated to 80°C by friction to obtain a dehydrated thermally conductive filler. S3: Vinyl silicone oil is purified by vacuum distillation at 200°C, vacuum degree -0.09MPa, and processing time of 1 hour to obtain vinyl silicone oil with volatile components removed; S4: The hydrogen-containing silicone oil on the side end is purified by vacuum distillation at 180°C, vacuum degree -0.9MPa, and processing time of 0.5 hours to obtain hydrogen-containing silicone oil with volatile components removed; S5: Dimethyl silicone oil is purified by vacuum distillation at 200°C, vacuum degree -0.9MPa, and processing time of 1 hour to obtain dimethyl silicone oil with volatile components removed; S6: 550 parts of the obtained dehydrated thermally conductive filler, 100 parts of devolatile vinyl silicone oil, 10 parts of devolatile hydrogen-containing silicone oil, 5 parts of devolatile dimethyl silicone oil, and 1 part of alkynyl alcohol inhibitor are mixed in a planetary mixer at 20 rpm for 60 min to obtain mixed adhesive A. S7: Mix the mixed rubber A obtained in step S6 with 1 part of platinum catalyst in a planetary mixer at 35 rpm and -0.095 MPa for 30 min to obtain mixed rubber B; S8: Calender the mixed rubber compound B obtained in S7 by 2mm, and vulcanize it at 100℃ in a tunnel furnace for 30min to obtain the low-volatile organosilicon thermal pad.
[0047] Example 2: S1: 600 parts of angular alumina with a median particle size of 40μm in the first-stage thermally conductive filler, 200 parts of spherical alumina with a median particle size of 5μm in the second-stage thermally conductive filler, and 200 parts of spherical alumina with a median particle size of 2μm in the third-stage thermally conductive filler are stirred in a high-speed mixer at 1500rpm for 1min to obtain a compound thermally conductive filler. S2: The compound thermally conductive filler obtained in S1 is mixed with 0.15% of the dehydrating agent by mass in a high-speed mixer at 1000 rpm for 10 min and heated to 75°C by friction to obtain a dehydrated thermally conductive filler. S3: Vinyl silicone oil is purified by vacuum distillation at 220°C, vacuum degree -0.09MPa, and processing time of 0.5 hours to obtain vinyl silicone oil with volatile components removed; S4: The hydrogen-containing silicone oil on the side end is purified by vacuum distillation at 180°C, vacuum degree -0.09MPa, and processing time of 1 hour to obtain hydrogen-containing silicone oil with volatile components removed; S5: Dimethyl silicone oil is purified by vacuum distillation at 210°C, vacuum degree -0.09MPa, and processing time of 1 hour to obtain dimethyl silicone oil with volatile components removed; S6: 720 parts of the obtained dehydrated thermally conductive filler, 100 parts of devolatile vinyl silicone oil, 12 parts of devolatile hydrogen-containing silicone oil, 3 parts of devolatile dimethyl silicone oil, and 1 part of alkynyl alcohol inhibitor are mixed in a planetary mixer at 10 rpm for 20 min to obtain mixed adhesive A. S7: Mix the mixed rubber A obtained in step S6 with 1 part of platinum catalyst in a planetary mixer at a speed of 25 rpm and a vacuum of -0.1 MPa for 40 min to obtain mixed rubber B; S8: Calender the mixed rubber compound B obtained in S7 to 3mm, and vulcanize it at 130℃ in a tunnel furnace for 15min to obtain the low-volatile organosilicon thermal pad.
[0048] Example 3: S1: 600 parts of spherical alumina with a median particle size of 50μm in the first-stage thermally conductive filler, 200 parts of spherical alumina with a median particle size of 6μm in the second-stage thermally conductive filler, and 200 parts of spherical alumina with a median particle size of 1μm in the third-stage thermally conductive filler are stirred in a high-speed mixer at 1000rpm for 2min to obtain a compound thermally conductive filler. S2: The compound thermally conductive filler obtained in S1 is mixed with 0.10% of the filler mass of dehydrating agent in a high-speed mixer at 1500 rpm for 5 minutes and heated to 85°C by friction to obtain a dehydrated thermally conductive filler. S3: Vinyl silicone oil is purified by vacuum distillation at 190°C, vacuum degree -0.1MPa, and processing time of 2 hours to obtain vinyl silicone oil with volatile components removed; S4: The hydrogen-containing silicone oil on the side end is purified by vacuum distillation at 190°C, vacuum degree -0.1MPa, and processing time of 0.5 hours to obtain hydrogen-containing silicone oil with volatile components removed; S5: Dimethyl silicone oil is purified by vacuum distillation at 230°C, vacuum degree -0.1MPa, and processing time of 0.5 hours to obtain dimethyl silicone oil with volatile components removed; S6: 1200 parts of the obtained dehydrated thermally conductive filler, 100 parts of devolatile vinyl silicone oil, 15 parts of devolatile hydrogen-containing silicone oil, 2 parts of devolatile dimethyl silicone oil, and 1 part of alkynyl alcohol inhibitor are mixed in a planetary mixer at 10 rpm for 20 min to obtain mixed adhesive A. S7: Mix the mixed rubber A obtained in step S6 with 1 part of platinum catalyst in a planetary mixer at a speed of 20 rpm and a vacuum of -0.1 MPa for 60 min to obtain mixed rubber B; S8: Calender the mixed rubber compound B obtained in S7 to 6mm, and vulcanize it at 150℃ in a tunnel furnace for 10min to obtain the low-volatile silicone thermal pad.
[0049] Comparative Example 1: The difference from Example 1 is that step S2 is omitted, and a compound thermally conductive filler that has not been dehydrated is used.
[0050] Comparative Example 2: The difference from Example 2 is that steps S3, S4, and S5 are omitted, and vinyl silicone oil, hydrogen-containing silicone oil, and dimethyl silicone oil with unremoved volatiles are used.
[0051] Comparative Example 3: The difference from Example 3 is that the thermally conductive filler, after removing moisture, is left to stand in an open environment at room temperature for one month before use.
[0052] Specifically, the thermally conductive filler with dehydrated material is first prepared according to steps S1 and S2 of Example 3. Then, it is left open for 30 days at room temperature (25±5℃) and relative humidity of 50±10%, and then used in subsequent steps S6 to S8. The rest is the same as in Example 3.
[0053] The low-volatility thermally conductive pads obtained in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests according to the following test items: 1. Thermal conductivity: Tested according to ASTM D5470 standard; 2. Low volatility performance: Take a 6mm thick low-volatile silicone thermal pad, die-cut it into a test sample with a diameter of 40mm, place it on the bottom of a 50mm diameter and 100mm high hollow glass cylinder on a heating table, cover it with a 60mm glass petri dish to form a sealed space, bake at 150℃ for 24 hours, and observe whether there is a fog or oily substance on the glass petri dish.
[0054] The test results are shown in Table 1:
[0055] Table 1 As shown in Table 1, the low-volatility thermally conductive pads prepared in Examples 1-3 all exhibit high thermal conductivity and excellent low-volatility performance (the watch glass is transparent). In Comparative Example 1, the lack of dehydration of the thermally conductive filler led to water molecules vaporizing at high temperatures, forming a mist. In Comparative Example 2, the lack of devolatiles in the silicone oil raw material resulted in the volatilization of small organic molecules, forming an oil film. Although dehydration treatment was performed during preparation in Comparative Example 3, moisture was reintroduced after one month due to moisture absorption, leading to a decrease in low-volatility performance (a slight mist appeared on the watch glass). This indicates that the dehydration treatment combined with subsequent moisture-proof properties of the present invention provides long-term stability, but the raw materials still need to be sealed and stored. A comparison between Example 3 and Comparative Example 3 further illustrates that the dehydrated thermally conductive filler obtained by the preparation method provided by the present invention has good drying stability, but storage conditions still require attention. In contrast, Examples 1-3, which directly use freshly prepared dehydrated filler, completely avoid moisture absorption problems, ensuring a high yield rate for batch production.
[0056] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.
[0057] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.
[0058] The above provides a detailed description of a low-volatile silicone thermal pad and its preparation method provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.
Claims
1. A method of making a low volatile organosilicon thermal pad, characterized by, Including the following steps: The thermally conductive filler (without moisture), vinyl silicone oil (without volatiles), hydrogen-containing silicone oil (without volatiles), dimethyl silicone oil (without volatiles), and alkynyl alcohol inhibitor are mixed in a specified mass ratio under the first specified conditions to obtain mixed rubber compound A. The mixed adhesive A and the platinum catalyst were vacuum stirred and mixed under a second specified condition to obtain mixed adhesive B; The mixed rubber compound B is calendered and vulcanized at high temperature under a third specified condition to obtain the low-volatile silicone thermal pad of a specified thickness.
2. The preparation method according to claim 1, characterized in that, The thermally conductive filler is composed of a first-stage thermally conductive filler, a second-stage thermally conductive filler and a third-stage thermally conductive filler mixed in a mass ratio of 6:2:
2. The first-stage thermally conductive filler is one of aluminum hydroxide, angular alumina, near-spherical alumina, or spherical alumina, with a median particle size of 40 μm to 70 μm; The second-stage thermally conductive filler is one of angular alumina, near-spherical alumina, or spherical alumina, with a median particle size of 5 μm to 7 μm; The third-stage thermally conductive filler is one of angular alumina, quasi-spherical alumina, or spherical alumina, with a median particle size of 1 μm to 3 μm.
3. The production method according to claim 1, characterized by, Also includes: The thermally conductive filler and the dehydrating agent are mixed and stirred in a high-speed mixer, and the temperature is raised to 75°C to 90°C by friction to obtain the dehydrated thermally conductive filler. Vinyl silicone oil, hydrogen-containing silicone oil, and dimethyl silicone oil were purified by vacuum distillation under the fourth specified conditions to obtain vinyl silicone oil, hydrogen-containing silicone oil, and dimethyl silicone oil after removing volatile components.
4. The production method according to claim 3, characterized by, The dehydrating agent is dimethyldimethoxysilane, and the amount of the dehydrating agent added is 0.05% to 0.3% of the total mass of the thermally conductive filler.
5. The preparation method according to claim 3, characterized in that, The fourth specified condition is a temperature of 180℃~230℃, a vacuum degree of -0.09MPa~-0.1MPa, and a processing time of 0.5~2 hours.
6. The preparation method according to claim 1, characterized in that, The vinyl silicone oil, excluding volatile components, is a double-ended vinyl silicone oil with a vinyl content of 0.4% to 0.6% and a viscosity of 400 cP to 600 cP. The hydrogen-containing silicone oil, excluding volatile components, is a side-end hydrogen-containing silicone oil with a hydrogen content of 0.09% to 0.11% and a viscosity of 150 cP to 250 cP. The viscosity of the dimethyl silicone oil, excluding volatile components, is 200 cP to 300 cP.
7. The preparation method according to claim 1, characterized in that, The alkynol inhibitor is 1-ethynyl-1-cyclohexanol, and the 1-ethynyl-1-cyclohexanol is pre-mixed and diluted with the vinyl silicone oil (excluding volatiles) at a mass ratio of 5:
95. The first specified condition is a stirring speed of 10~20 rpm and a stirring time of 20~60 min.
8. The preparation method according to claim 1, characterized in that, The platinum catalyst is chloroplatinic acid, and the chloroplatinic acid is pre-mixed and diluted with the vinyl silicone oil (excluding volatiles) to a platinum content of 3000ppm to 5000ppm. The second specified conditions are a stirring speed of 10~35 rpm, a vacuum degree of -0.09~-0.1 MPa, and a stirring time of 30~90 min.
9. The method of claim 1, wherein, The third specified condition is a temperature of 100℃~150℃ and a vulcanization time of 10min~30min; the specified thickness is 1~6mm.
10. A low volatile silicone thermal pad, characterized in that, The product is prepared by the method according to any one of claims 1 to 9, comprising 100 to 500 parts by weight of vinyl silicone oil (excluding volatiles), 3 to 20 parts by weight of hydrogen-containing silicone oil (excluding volatiles), 1 to 10 parts by weight of dimethyl silicone oil (excluding volatiles), 400 to 1500 parts by weight of thermally conductive filler (excluding moisture), 1 to 5 parts by weight of alkynyl alcohol inhibitor, and 0.5 to 5 parts by weight of platinum catalyst.