Low-sagging potting adhesive and preparation method thereof

Abstract

The application relates to the technical field of pouring sealant, and specifically discloses a low-settling pouring sealant and a preparation method thereof. The low-settling pouring sealant comprises an A component and a B component, the A component comprises the following raw materials in parts by weight: 50-60 parts of polysiloxane; 10-15 parts of a heat-conducting material; 10-15 parts of mixed white carbon black; 10-15 parts of a crosslinking agent; and 5-8 parts of a defoaming agent; the B component comprises the following raw materials in parts by weight: 50-60 parts of polysiloxane; 10-15 parts of a heat-conducting material; 10-15 parts of mixed white carbon black; and 0.5-0.8 parts of a catalyst; the mixed white carbon black comprises ion-modified white carbon black and coupling agent-modified white carbon black in a weight ratio of (1.8-2):1; and the preparation method is as follows: I, preparation of the A and B components; II, two-component mixing: to obtain the low-settling pouring sealant. The product has the advantages of high anti-settling performance and good heat-conducting capacity, and the settling rate is not higher than 10.36 wt%.

Description

Technical Field

[0001] This application relates to the technical field of potting compounds, and in particular to a low-settling potting compound and its preparation method. Background Technology

[0002] Potting compound is a liquid, free-flowing substance before curing, commonly used for bonding, sealing, potting, and coating protection of electronic components. During application, potting compound is injected into devices containing electronic components and circuitry. After curing, it becomes an insulating material with waterproof, moisture-proof, thermally conductive, and corrosion-resistant properties. There are three main types of potting compounds: epoxy resin potting compounds, silicone potting compounds, and polyurethane potting compounds. Among them, silicone potting compounds have become a popular material due to their excellent electrical insulation properties, resistance to high and low temperatures, and self-healing properties after cracking.

[0003] One of the more commonly used types of silicone potting compounds is the two-component silicone potting compound. This type of potting compound requires two components to work. One component includes polysiloxane and crosslinking agent, while the other component includes polysiloxane and catalyst. When using it, the two components need to be mixed in a certain ratio before filling.

[0004] As potting compounds become increasingly widely used, it has been found that due to the low thermal conductivity of polysiloxanes, a large amount of heat accumulates inside the potting compound during the use of electronic devices that generate significant internal heat. This heat is difficult to dissipate quickly, leading to a rapid increase in the internal temperature of the electronic devices, accelerated component aging, and potential safety hazards such as fires. Currently, a common method is to add thermally conductive materials to improve the thermal conductivity of silicone potting compounds. However, current thermally conductive materials (such as silicon micropowder, boron nitride, and aluminum oxide) have low compatibility with polysiloxanes. During the curing process, phase separation is severe, and in extreme cases, the thermally conductive material may agglomerate and settle within the potting compound system. Therefore, the cured potting compound cannot fully exert its thermal conductivity, and its thermal performance still fails to meet application requirements. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a low-settling potting compound and its preparation method.

[0006] Firstly, this application provides a low-settling potting compound, employing the following technical solution:

[0007] A low-settling potting compound includes component A and component B. Component A comprises the following raw materials in parts by weight: 50-60 parts polysiloxane; 10-15 parts thermally conductive material; 10-15 parts mixed silica; 10-15 parts crosslinking agent; and 5-8 parts defoamer. Component B comprises the following raw materials in parts by weight: 50-60 parts polysiloxane; 10-15 parts thermally conductive material; 10-15 parts mixed silica; and 0.5-0.8 parts catalyst. The mixed silica comprises ion-modified silica and coupling agent-modified silica in a weight ratio of (1.8-2):1.

[0008] Preferably, the weight ratio of the ion-modified silica to the coupling agent-modified silica is 1.95:1.

[0009] By adopting the above technical solution, this application uses mixed silica to partially replace the existing thermally conductive materials. The coupling agent-modified silica has extremely strong oleophilic and hydrophobic properties, high compatibility with polysiloxanes, and low agglomeration in the potting compound system, resulting in a very low possibility of clumping or sedimentation, thus fully utilizing its thermal conductivity. The ion-modified silica has highly thermally conductive cationic segments on its surface. During the stirring process in potting compound preparation, these cationic segments form a thermally conductive network within the potting compound system, significantly reducing the thermal resistance of the potting compound. Simultaneously, due to the presence of highly thermally conductive cationic segments... The ionic segments also possess a certain degree of oleophilicity, which can reduce the agglomeration of ion-modified silica in the potting compound system. More importantly, the hollow structure of the thermally conductive mesh can accommodate coupling agent-modified silica and particulate thermally conductive materials embedded in the mesh, improving the uniformity of the thermally conductive materials and mixed silica dispersion in the potting compound system. The large-area agglomeration of particles inside the potting compound is greatly reduced, and the sedimentation rate is no higher than 10.36 wt%. The thermal conductivity of the potting compound is further improved as a result. Experimental tests show that the thermal conductivity of the low sedimentation potting compound of this application is no less than 3.14 W / (m·K).

[0010] This application also strictly controls the weight ratio between mixed silica and thermally conductive materials. If the amount of mixed silica is too large, although it can significantly improve the anti-settling performance of the potting compound, the thermal conductivity of the mixed silica is lower than that of the thermally conductive material, so the improvement in the thermal conductivity of the potting compound is not significant. If the amount of mixed silica is too small, serious agglomeration and sedimentation will still occur in the potting compound system.

[0011] Furthermore, this application also controls the weight ratio of ion-modified silica and coupling agent-modified silica in the mixed silica. If the amount of ion-modified silica is too large, the formation degree of the thermal conductive network in the system is already saturated, and the thermal conductivity of the potting compound will not be significantly improved, but will instead increase the production cost. If the amount of coupling agent-modified silica is too large, its thermal conductivity is lower than that of ion-modified silica and thermal conductive materials, so the improvement in the thermal conductivity of the potting compound is insufficient and cannot meet the requirements. Experiments have shown that when the weight ratio of ion-modified silica to coupling agent-modified silica is controlled at 1.95:1, the thermal conductivity of the potting compound is the highest, reaching 3.27 W / (m·K).

[0012] Preferably, the ion-modified silica is prepared by the following method:

[0013] S1. N-methylimidazolium and bromoalkane are mixed evenly in a molar ratio of 1:(1.1-1.2) and stirred for 12-14 h under inert gas protection and at a reaction temperature of 80-82℃ to obtain the initial product. The initial product is washed, rotary evaporated, and dried to constant weight to obtain the ion modifier.

[0014] S2. Disperse the ionic modifier obtained in step S1 in water and stir at 50-55℃ for 30-35 min. Then add silica and stir at 80-82℃ for 3-5 h to obtain a liquid mixture. Let it stand until it solidifies and then dry it to constant weight to obtain ionic modified silica. The weight ratio of the ionic modifier, water and silica is 1:(65-67):(10-11).

[0015] Preferably, in step S1, the bromoalkane is one of bromobutane, bromoheptane, and bromooctane.

[0016] By adopting the above technical solution, this application uses N-methylimidazolium and bromoalkane (one of n-butane, n-heptane, and n-octane) to prepare an ion modifier with lipophilic and thermally conductive properties, and then modifies silica to obtain ion-modified silica. Furthermore, the ion-modified silica obtained by using n-heptane as a reactant has a more uniform thermally conductive network structure compared to the ion-modified silica obtained by using n-butane and n-octane as reactants, thus possessing better thermal conductivity. Experimental data shows that, compared to n-butane and n-octane, the ion-modified silica obtained by using n-heptane as a reactant can increase the thermal conductivity of the potting compound by 9.15-10.19%.

[0017] Preferably, the coupling agent-modified silica is prepared by the following method:

[0018] A pre-hydrolyzed solution was obtained by mixing a coupling agent with water at a weight ratio of (1-1.1):2; a silica and an organic solvent at a weight ratio of (8-12):(15-18) were mixed evenly and emulsified for 10-12 minutes to obtain a silica emulsion; the pre-hydrolyzed solution and silica emulsion at a weight ratio of 1:(8-10) were mixed evenly, the pH of the system was adjusted to 7-9, and then stirred at 48-55℃ for 4-8 hours, allowed to stand for 20-25 hours, and then dried under vacuum at 70-75℃ until the system reached constant weight to obtain coupling agent modified silica.

[0019] Preferably, the temperature is 50°C.

[0020] By adopting the above technical solution, this application uses a coupling agent to perform surface treatment on silica at a certain temperature and a certain pH, resulting in a reduced specific surface area of ​​the coupling agent-modified silica, thus possessing extremely strong dispersibility. Its wettability and compatibility with polysiloxane are both at a high level, and it can be fully dispersed inside the potting compound.

[0021] In the reaction system of this application, if the temperature is too high, the coupling agent hydrolyzes too quickly, resulting in significant self-polymerization; if the temperature is too low, the coupling agent hydrolyzes too slowly, leading to insufficient reaction. Both excessively high and low temperatures reduce the modification rate of silica. Therefore, this application strictly controls the reaction temperature to maintain a moderate hydrolysis rate of the coupling agent, significantly optimizing its modification effect on silica. Experimental data demonstrates that the coupling agent exhibits the best modification effect on silica at 50℃, resulting in the highest anti-settling properties and thermal conductivity of the potting compound.

[0022] Preferably, the weight ratio of the pre-hydrolyzed solution to the silica emulsion is 1:9.2.

[0023] By adopting the above technical solution, this application controls the weight ratio of the coupling agent and the silica emulsion, thereby controlling the weight ratio of the coupling agent and the silica, optimizing the modification effect of the coupling agent on the silica, and further improving the anti-settling performance and thermal conductivity of the potting compound. Experimental data shows that when the weight ratio of the pre-hydrolyzed liquid to the silica emulsion is 1:9.2, the anti-settling performance and thermal conductivity of the potting compound are the highest.

[0024] Preferably, the thermally conductive material includes at least one of silicon micropowder, boron nitride, and aluminum oxide.

[0025] Secondly, this application provides a method for preparing a low-settling potting compound, comprising the following steps: preparation of components I, A, and B: mixing polysiloxane, thermally conductive material, mixed silica, defoamer, and crosslinking agent uniformly to obtain component A; mixing polysiloxane, thermally conductive material, mixed silica, and catalyst uniformly to obtain component B;

[0026] II. Two-component mixing: Mix component A and component B in a weight ratio of 1:(0.95-1.05) until homogeneous, and then degas under vacuum to obtain a low-settling potting compound.

[0027] By adopting the above technical solution, this application has prepared a low-settling potting compound with good anti-settling performance and thermal conductivity. The preparation method is simple, the raw materials are readily available, and it has high feasibility and practicality.

[0028] In summary, this application has the following beneficial technical effects:

[0029] 1. The low-settling potting compound of this application has a weak phase separation phenomenon, high anti-settling performance, a sedimentation rate of no more than 10.36wt%, and a thermal conductivity of no less than 3.14W / (m·K), which reduces the rate of temperature rise inside electronic devices, slows down the aging speed of components, and greatly reduces the possibility of safety problems such as fires.

[0030] 2. The preparation method of the low-settling potting compound in this application is simple, the raw materials are readily available, and it has high feasibility and practicality. Detailed Implementation

[0031] Material source

[0032] Unless otherwise specified, all raw materials used in this application are commercially available products, specifically:

[0033] The silica was purchased from Lingshou County Baiyi Mineral Products Processing Plant and Guangdong Hengtian New Materials Technology Co., Ltd., with average particle sizes of 8±0.5um, 12±0.5um, 5±0.1um and 6±0.1um, respectively.

[0034] The hydroxyl-terminated polydimethylsiloxane was purchased from Zhejiang Rongli High-Tech Materials Co., Ltd., CAS No. 63148-60-7;

[0035] The silica powder was purchased from Lingshou County Runshi Mineral Powder Factory, with a particle size of 2000 mesh;

[0036] Boron nitride was purchased from Zhengzhou Shengyu Chemical Products Co., Ltd., with a particle size of 1-10 μm, a bulk density of 3.48 g / cm3, and a melting point ≥2450℃;

[0037] Alumina was purchased from Zibo Nuoda Chemical Co., Ltd., with a particle size of 5000 mesh;

[0038] Dimethyl silicone oil was purchased from Jinan Hongtai Chemical Co., Ltd., CAS number 9006-65-9;

[0039] The polymethylhydrosiloxane was purchased from Wuhan Jixin Yibang Biotechnology Co., Ltd., CAS No. 63148-57-2;

[0040] The coupling agent was purchased from Shandong Yousuo Chemical Technology Co., Ltd., and its molecular formula is C. 10 H 20 O5Si, CAS number is 2530-85-0;

[0041] Anhydrous ethanol was purchased from Shanghai Aladdin Reagent Co., Ltd., analytical grade AR.

[0042] Butane bromide, octane bromide, and heptane bromide were all purchased from Jinan Quanxing New Materials Co., Ltd.

[0043] N-methylimidazole was purchased from Hubei Jianchu Biomedical Co., Ltd., with the molecular formula 616-47-7.

[0044] The present application will be further described in detail below with reference to preparation examples, embodiments and comparative examples.

[0045] Preparation Example 1.1

[0046] The preparation method of ion-modified silica includes the following steps:

[0047] S1. Mix 0.82 kg N-methylimidazole and 1.507 kg n-bromobutane evenly, and stir for 12 h under nitrogen protection and reaction temperature of 82 °C to obtain the initial product. Wash the initial product, rotary evaporate, and dry to constant weight to obtain the ion modifier.

[0048] S2. Disperse 1 kg of the ion modifier obtained in step S1 in 65 kg of water and stir at 50°C for 35 min. Then add 10 kg of silica with a particle size of 8 ± 0.5 μm and stir at 82°C for 3 h to obtain a liquid mixture. Let it stand until it solidifies and then dry it to constant weight to obtain ion-modified silica.

[0049] Preparation Example 1.2

[0050] The preparation method of ion-modified silica includes the following steps:

[0051] S1. Mix 0.82 kg N-methylimidazole and 1.644 kg n-bromobutane evenly, and stir for 14 h under nitrogen protection and reaction temperature of 80 °C to obtain the initial product. Wash the initial product, rotary evaporate, and dry to constant weight to obtain the ion modifier.

[0052] S2. Disperse 1 kg of the ion modifier obtained in step S1 in 67 kg of water and stir at 55°C for 30 min. Then add 11 kg of silica with a particle size of 12 ± 0.5 μm and stir at 80°C for 5 h to obtain a liquid mixture. Let it stand until it solidifies and then dry it to constant weight to obtain ion-modified silica.

[0053] Preparation Example 2.1

[0054] The preparation method of ion-modified silica differs from that of Preparation Example 1.1 in that 1.507 kg of n-butane bromide in step S1 is replaced with 2.123 kg of n-octane bromide, while the rest is the same as in Preparation Example 1.1.

[0055] Preparation Example 2.2

[0056] The preparation method of ion-modified silica differs from that of Preparation Example 1.1 in that 1.507 kg of n-butane bromide in step S1 is replaced with 1.969 kg of n-heptane bromide, while the rest is the same as in Preparation Example 1.1.

[0057] Preparation Example 3.1

[0058] The preparation method of coupling agent modified silica includes the following steps:

[0059] 1 kg of coupling agent was dispersed in 2 kg of water to obtain a pre-hydrolyzed solution; then 8 kg of silica with a particle size of 5 ± 0.1 μm was dispersed in 18 kg of anhydrous ethanol, and after emulsification for 12 min, a silica emulsion was obtained; 1 kg of pre-hydrolyzed solution and 10 kg of silica emulsion were mixed evenly, and the pH of the system was adjusted until pH = 7. Then, the mixture was stirred at 55 °C for 4 h, allowed to stand for 25 h, and then dried under vacuum at 70 °C until the system reached constant weight to obtain coupling agent modified silica.

[0060] Preparation Example 3.2

[0061] The preparation method of coupling agent modified silica includes the following steps:

[0062] 1.1 kg of coupling agent was dispersed in 2 kg of water to obtain a pre-hydrolyzed solution; then 12 kg of silica with a particle size of 6 ± 0.1 μm was dispersed in 15 kg of anhydrous ethanol, and after emulsification for 10 min, a silica emulsion was obtained; 1 kg of pre-hydrolyzed solution and 8 kg of silica emulsion were mixed evenly, and the pH of the system was adjusted until pH = 9. Then, the mixture was stirred at 48 °C for 8 h, allowed to stand for 20 h, and then dried under vacuum at 75 °C until the system reached constant weight to obtain coupling agent modified silica.

[0063] Preparation Example 4.1

[0064] The preparation method of coupling agent modified silica differs from that of preparation example 3.1 in that the reaction temperature is 54℃, while the rest is the same as that of preparation example 3.1.

[0065] Preparation Example 4.2

[0066] The preparation method of coupling agent modified silica differs from that of preparation example 3.1 in that the reaction temperature is 53℃, while the rest is the same as that of preparation example 3.1.

[0067] Preparation Example 4.3

[0068] The preparation method of coupling agent modified silica differs from that of preparation example 3.1 in that the reaction temperature is 52℃, while the rest is the same as that of preparation example 3.1.

[0069] Preparation Example 4.4

[0070] The preparation method of coupling agent modified silica differs from that of preparation example 3.1 in that the reaction temperature is 51℃, while the rest is the same as that of preparation example 3.1.

[0071] Preparation Example 4.5

[0072] The preparation method of coupling agent modified silica differs from that of preparation example 3.1 in that the reaction temperature is 50℃, while the rest is the same as that of preparation example 3.1.

[0073] Preparation Example 4.6

[0074] The preparation method of coupling agent modified silica differs from that of preparation example 3.1 in that the reaction temperature is 49℃, while the rest is the same as that of preparation example 3.1.

[0075] Preparation Example 4.7

[0076] The preparation method of coupling agent modified silica differs from that of preparation example 3.1 in that the reaction temperature is 48℃, while the rest is the same as that of preparation example 3.1.

[0077] Preparation Example 4.8

[0078] The preparation method of coupling agent modified silica includes the following steps:

[0079] 1 kg of coupling agent was dispersed in 2 kg of water to obtain a pre-hydrolyzed solution; then 8 kg of silica with a particle size of 5 ± 0.1 μm was dispersed in 18 kg of anhydrous ethanol, and the emulsification reaction was carried out for 12 min to obtain a silica emulsion; 1 kg of pre-hydrolyzed solution and 10 kg of silica emulsion were mixed evenly, the pH of the system was adjusted until pH = 7, then stirred at 58 °C for 4 h, allowed to stand for 25 h, and then dried under vacuum at 70 °C until the system reached constant weight to obtain coupling agent modified silica.

[0080] Preparation Example 4.9

[0081] The preparation method of coupling agent modified silica includes the following steps:

[0082] 1 kg of coupling agent was dispersed in 2 kg of water to obtain a pre-hydrolyzed solution; then 8 kg of silica with a particle size of 5 ± 0.1 μm was dispersed in 18 kg of anhydrous ethanol, and the emulsification reaction was carried out for 12 min to obtain a silica emulsion; 1 kg of pre-hydrolyzed solution and 10 kg of silica emulsion were mixed evenly, the pH of the system was adjusted until pH = 7, then stirred at 45 °C for 4 h, allowed to stand for 25 h, and then dried under vacuum at 70 °C until the system reached constant weight to obtain coupling agent modified silica.

[0083] Preparation Example 5.1

[0084] The preparation method of the coupling agent modified silica differs from that of Preparation Example 3.1 in that the amount of silica emulsion used is 9.2 kg, while the rest is the same as in Preparation Example 3.1.

[0085] Preparation Example 5.2

[0086] The preparation method of coupling agent modified silica includes the following steps:

[0087] 1 kg of coupling agent was dispersed in 2 kg of water to obtain a pre-hydrolyzed solution; then 8 kg of silica with a particle size of 5 ± 0.1 μm was dispersed in 18 kg of anhydrous ethanol, and after emulsification for 12 min, a silica emulsion was obtained; 1 kg of pre-hydrolyzed solution and 6 kg of silica emulsion were mixed evenly, and the pH of the system was adjusted until pH = 7. Then, the mixture was stirred at 55 °C for 4 h, allowed to stand for 25 h, and then dried under vacuum at 70 °C until the system reached constant weight to obtain coupling agent modified silica.

[0088] Preparation Example 5.3

[0089] The preparation method of coupling agent modified silica includes the following steps:

[0090] 1 kg of coupling agent was dispersed in 2 kg of water to obtain a pre-hydrolyzed solution; then 8 kg of silica with a particle size of 5 ± 0.1 μm was dispersed in 18 kg of anhydrous ethanol, and the emulsification reaction was carried out for 12 min to obtain a silica emulsion; 1 kg of pre-hydrolyzed solution and 12 kg of silica emulsion were mixed evenly, the pH of the system was adjusted until pH = 7, then stirred at 55 °C for 4 h, allowed to stand for 25 h, and then dried under vacuum at 70 °C until the system reached constant weight to obtain coupling agent modified silica.

[0091] Example 1.1

[0092] A method for preparing a low-settling potting compound includes the following steps:

[0093] Preparation of components I, A, and B: Component A was obtained by uniformly mixing 50 kg of hydroxyl-terminated polydimethylsiloxane, 15 kg of thermally conductive material (6 kg of silica powder, 3 kg of boron nitride, and 6 kg of aluminum oxide), 10 kg of mixed silica (6.4 kg of ion-modified silica prepared in Preparation Example 1.1 and 3.6 kg of coupling agent-modified silica prepared in Preparation Example 3.1), 5 kg of defoamer (dimethyl silicone oil), and 15 kg of crosslinking agent (polymethylhydrosiloxane); Component B was obtained by uniformly mixing 50 kg of hydroxyl-terminated polydimethylsiloxane, 15 kg of thermally conductive material (6 kg of silica powder, 3 kg of boron nitride, and 6 kg of aluminum oxide), 10 kg of mixed silica (6.4 kg of ion-modified silica prepared in Preparation Example 1.1 and 3.6 kg of coupling agent-modified silica prepared in Preparation Example 3.1), and 0.8 kg of platinum catalyst.

[0094] II. Two-component mixing: Mix 50kg of component A and 47.5kg of component B evenly, and then degas under vacuum to obtain a low-settling potting compound.

[0095] Example 1.2

[0096] A method for preparing a low-settling potting compound includes the following steps:

[0097] Preparation of components I, A, and B: Component A was obtained by uniformly mixing 60 kg of hydroxyl-terminated polydimethylsiloxane, 10 kg of silica powder, 15 kg of mixed silica (10 kg of ion-modified silica prepared in Preparation Example 1.2 and 5 kg of coupling agent-modified silica prepared in Preparation Example 3.2), 8 kg of defoamer (dimethyl silicone oil), and 10 kg of crosslinking agent (polymethylhydrosiloxane); Component B was obtained by uniformly mixing 60 kg of hydroxyl-terminated polydimethylsiloxane, 10 kg of thermally conductive material (4 kg of silica powder, 2 kg of boron nitride, and 4 kg of aluminum oxide), 15 kg of mixed silica (10 kg of ion-modified silica prepared in Preparation Example 1.2 and 5 kg of coupling agent-modified silica prepared in Preparation Example 3.2), and 0.5 kg of platinum catalyst.

[0098] II. Two-component mixing: Mix 50kg of component A and 52.5kg of component B evenly, and then degas under vacuum to obtain a low-settling potting compound.

[0099] Example 1.3

[0100] A method for preparing a low-settling potting compound differs from Example 1.1 in that: in step I, the amount of ion-modified silica prepared in Example 1.1 is 6.61 kg, and the amount of coupling agent-modified silica prepared in Example 3.1 is 3.39 kg; the rest are the same as in Example 1.1.

[0101] Examples 2.1-2.2

[0102] A method for preparing a low-settling potting compound differs from Example 1.1 in that: in step I, the ion-modified silica prepared in Preparation Example 1.1 is replaced with the ion-modified silica prepared in Preparation Examples 2.1-2.2, while the rest is the same as in Example 1.1.

[0103] Examples 3.1-3.9

[0104] A method for preparing a low-settling potting compound differs from Example 1.1 in that: in step I, the coupling agent modified silica prepared in Preparation Example 3.1 is replaced with the coupling agent modified silica prepared in Preparation Examples 4.1-4.9, and the rest is the same as in Example 1.1.

[0105] Examples 4.1-4.3

[0106] A method for preparing a low-settling potting compound differs from Example 1.1 in that: in step I, the coupling agent modified silica prepared in Preparation Example 3.1 is replaced with the coupling agent modified silica prepared in Preparation Examples 5.1-5.3, and the rest is the same as in Example 1.1.

[0107] Comparative Example 1

[0108] The difference from Example 1.1 is that in step I, 10 kg of mixed silica is replaced with 4 kg of silica powder, 2 kg of boron nitride and 4 kg of aluminum oxide, and the rest is the same as in Example 1.1.

[0109] Comparative Example 2

[0110] The difference from Example 1.1 is that in step I, 15 kg of thermally conductive material was replaced with 11.05 kg of ion-modified silica prepared in Example 1.1 and 3.95 kg of coupling agent-modified silica prepared in Example 3.1, while the rest were the same as in Example 1.1.

[0111] Comparative Example 3

[0112] The difference from Example 1.1 is that in step I, the amount of thermally conductive material (8 kg silicon micro powder, 4 kg boron nitride and 8 kg aluminum oxide) is 20 kg, and the amount of mixed silica (3.21 kg of ion-modified silica prepared in Example 1.1 and 1.79 kg of coupling agent-modified silica prepared in Example 3.1) is 5 kg, and the rest is the same as in Example 1.1.

[0113] Comparative Example 4

[0114] The difference from Example 1.1 is that in step I, the amount of thermally conductive material (2 kg silicon micro powder, 1 kg boron nitride and 2 kg aluminum oxide) is 5 kg, and the amount of mixed silica (12.86 kg of ion-modified silica prepared in Example 1.1 and 7.14 kg of coupling agent-modified silica prepared in Example 3.1) is 20 kg, and the rest is the same as in Example 1.1.

[0115] Comparative Example 5

[0116] The difference from Example 1.1 is that in step I, the ion-modified silica prepared in Example 1.1 is removed, and the amount of coupling agent-modified silica prepared in Example 3.1 is 10 kg. All other aspects are the same as in Example 1.1.

[0117] Comparative Example 6

[0118] The difference from Example 1.1 is that in step I, the coupling agent modified silica obtained in Preparation Example 3.1 is removed, and the amount of ion-modified silica obtained in Preparation Example 1.1 is 10 kg. All other aspects are the same as in Example 1.1.

[0119] Comparative Example 7

[0120] The difference from Example 1.1 is that in step I, the amount of ion-modified silica prepared in Example 1.1 is 4 kg, and the amount of coupling agent-modified silica prepared in Example 3.1 is 6 kg. The rest are the same as in Example 1.1.

[0121] Comparative Example 8

[0122] The difference from Example 1.1 is that in step I, the amount of ion-modified silica prepared in Example 1.1 is 8 kg, and the amount of coupling agent-modified silica prepared in Example 3.1 is 2 kg. All other aspects are the same as in Example 1.1.

[0123] Performance testing

[0124] 1. Anti-settling performance: Take 500g of each of the potting compound prepared in Examples 1.1-4.3 and Comparative Examples 1-8, and shake them at a speed of 100r / min for 168h using a shaker. Remove the upper layer of fluid adhesive, measure the mass of the lower layer of sediment and record it as m (g), calculate the sedimentation rate wt% = (m / 500) × 100%, and record the results in Table 1;

[0125] 2. Thermal conductivity: The thermal conductivity of the potting compounds prepared in Examples 1.1-4.3 and Comparative Examples 1-8 was determined according to the method described in ASTM D-5470, and the results are recorded in Table 1.

[0126] Table 1

[0127]

[0128]

[0129] Data Analysis:

[0130] As can be seen from Table 1, the low-settling potting compound obtained in Examples 1.1-1.2 has a sedimentation rate as low as 10.20-10.36 wt% and a thermal conductivity of 3.17-3.21 W / (m·K). This proves that the present application uses mixed silica to partially replace the existing thermally conductive material, so that the coupling agent modified silica and ion modified silica can fully exert their synergistic effect, improve the compatibility of the overall thermally conductive material and the mixed silica with polysiloxane, greatly reduce the phase separation phenomenon inside the potting compound, and significantly improve the anti-settling performance and thermal conductivity.

[0131] The low-settling potting compound obtained in Example 1.3 has a lower settling rate than that in Example 1.1 and a higher thermal conductivity than that in Example 1.1. This proves that this application further optimizes the synergistic effect of the two by strictly controlling the weight ratio of ion-modified silica and coupling agent-modified silica in the mixed silica, thereby further improving the thermal conductivity of the potting compound.

[0132] The sedimentation rate and thermal conductivity of the low-settling potting compound obtained in Example 2.1 were not significantly different from those in Example 1.1, while the sedimentation rate of the low-settling potting compound obtained in Example 2.2 was lower than that in Example 1.1, and the thermal conductivity was higher than that in Example 1.1. This proves that the ion modifier prepared by using brominated n-heptane as the reaction raw material in this application can evenly improve the uniformity of the thermal conductivity network and the thermal conductivity of ion-modified silica, thereby further improving the anti-settling performance and thermal conductivity of the potting compound.

[0133] The sedimentation rate and thermal conductivity of the low-settling potting compounds obtained in Examples 3.1-3.4 and 3.6-3.7 were not significantly different from those in Example 1.1. The sedimentation rate of the low-settling potting compound obtained in Example 3.5 was lower than that in Example 1.1, while its thermal conductivity was higher. The sedimentation rate of the low-settling potting compound obtained in Examples 3.8-3.9 was higher than that in Example 1.1, while its thermal conductivity was lower. This demonstrates that by strictly controlling the reaction temperature, this application has achieved a relatively moderate hydrolysis rate of the coupling agent, significantly optimizing the modification effect of the coupling agent on silica, and further improving the anti-settling performance and thermal conductivity of the potting compound.

[0134] The low-settling potting compound obtained in Example 4.1 had a lower settling rate and a higher thermal conductivity than that obtained in Example 1.1. The low-settling potting compounds obtained in Examples 4.2-4.3 had a higher settling rate and a lower thermal conductivity than those obtained in Example 1.1. This demonstrates that by further controlling the weight ratio of the pre-hydrolyzed solution and the silica emulsion, this application optimized the modification effect of the coupling agent on silica, further improving the anti-settling performance and thermal conductivity of the potting compound.

[0135] The settling of the potting compounds obtained in Comparative Examples 1-2 and 5-6 was higher than that in Example 1.1, and the thermal conductivity was lower than that in Example 1.1. This proves that the present application uses mixed silica to partially replace the existing thermal conductive material, so that the coupling agent modified silica and ion modified silica can fully exert their synergistic effect, improve the overall compatibility of the thermal conductive material and the mixed silica with polysiloxane, greatly reduce the phase separation phenomenon inside the potting compound, and significantly improve the anti-settling performance and thermal conductivity.

[0136] The settling of the potting compound obtained in Comparative Examples 3-4 was higher than that in Example 1.1, and the thermal conductivity was lower than that in Example 1.1. This proves that by strictly controlling the weight ratio between mixed silica and thermally conductive materials, this application further improves the anti-settling performance and thermal conductivity of the low-settling potting compound.

[0137] The settling of the potting compound obtained in Comparative Examples 7-8 was higher than that in Example 1.1, and the thermal conductivity was lower than that in Example 1.1. This proves that the present application has further optimized the synergistic effect of the two by strictly controlling the weight ratio of ion-modified silica and coupling agent-modified silica in the mixed silica, thereby further improving the thermal conductivity of the potting compound.

[0138] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1.A low-set pouring sealant, comprising an A component and a B component, characterized in that: the A component comprises the following raw materials in parts by weight: 50-60 parts of polysiloxane; 10-15 parts of a heat-conducting material; 10-15 parts of mixed white carbon black; 10-15 parts of a crosslinking agent; and 5-8 parts of a defoaming agent; the B component comprises the following raw materials in parts by weight: 50-60 parts of polysiloxane; 10-15 parts of a heat-conducting material; 10-15 parts of mixed white carbon black; and 0.5-0.8 parts of a catalyst; the heat-conducting material comprises at least one of silicon powder, boron nitride and aluminum trioxide; the mixed white carbon black comprises ion-modified white carbon black and coupling agent-modified white carbon black in a weight ratio of (1.8-2) : 1; the ion-modified white carbon black is prepared by the following method: S1. mixing N-methyl imidazole and bromoalkane in a molar ratio of 1: (1.1-1.2) uniformly, stirring under inert gas protection at a reaction temperature of 80-82 ℃ for 12-14 h to obtain a primary product, washing, rotary evaporation and drying to constant weight to obtain an ion modifier; S2. dispersing the ion modifier obtained in step S1 in water, stirring at a temperature of 50-55 ℃ for 30-35 min, then adding white carbon black and stirring at a temperature of 80-82 ℃ for 3-5 h to obtain a liquid mixture, which is left to condense to a solid state and then dried to constant weight, to obtain ion-modified white carbon black, the weight ratio of the ion modifier, water and white carbon black being 1: (65-67) : (10-11) ; the coupling agent-modified white carbon black is prepared by the following method: mixing a coupling agent and water in a weight ratio of (1-1.1) : 2 to obtain a pre-hydrolysis solution; mixing white carbon black and an organic solvent in a weight ratio of (8-12) : (15-18) uniformly, emulsifying for 10-12 min to obtain a white carbon black emulsion; mixing the pre-hydrolysis solution and the white carbon black emulsion in a weight ratio of 1: (8-10) uniformly, adjusting the pH of the system to 7-9, then stirring at a temperature of 48-55 ℃ for 4-8 h, leaving for 20-25 h, and then drying to constant weight of the system under vacuum at a temperature of 70-75 ℃ to obtain coupling agent-modified white carbon black; the weight ratio of the ion-modified white carbon black and the coupling agent-modified white carbon black is 1.95: 1; in step S1, the bromoalkane is one of bromo-n-butane, bromo-n-heptane and bromo-n-octane; when preparing the coupling agent-modified white carbon black, stirring is performed at a temperature of 50 ℃ for 4-8 h; the weight ratio of the pre-hydrolysis solution and the white carbon black emulsion is 1: 9.2; and the low-set pouring sealant comprises the following steps: I. preparation of the A and B components: mixing polysiloxane, a heat-conducting material, mixed white carbon black, a defoaming agent and a crosslinking agent uniformly to obtain the A component; and mixing polysiloxane, a heat-conducting material, mixed white carbon black and a catalyst uniformly to obtain the B component; II. mixing of the two components: mixing the A component and the B component in a weight ratio of 1: (0.95-1.05) uniformly, and then vacuum degassing to obtain the low-set pouring sealant. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2. The low-sag potting adhesive of claim 1, wherein: ​ 3. The low-sag potting adhesive of claim 1, wherein: ​ 4. The low-sag potting adhesive of claim 1, wherein: ​ 5. The low-sag potting adhesive of claim 1, wherein: ​ 6. A process for preparing the low-sag potting sealant of claim 1, characterized by: ​ ​ ​

Images