Dealcoholized organic silicone sealant as well as preparation method and application thereof

Abstract

The invention relates to the technical field of sealants, and particularly discloses a dealcoholized organic silicone sealant as well as a preparation method and application thereof. The dealcoholized organic silicone sealant is prepared from the following raw materials in parts by weight: 100 to 200 parts of alpha, omega-dihydroxy polydimethylsiloxane, 150 to 400 parts of filler, 5 to 15 parts of cross-linking agent, 2 to 8 parts of catalyst and 1 to 5 parts of coupling agent, the filler comprises surface-modified aluminum hydroxide and calcium carbonate. The raw material components of the dealcoholized organic silicone sealant provided by the invention have synergistic interaction, and the prepared dealcoholized organic silicone sealant has good rapid curing performance, heat conduction performance, electrical insulation performance and adhesive performance, is not prone to yellowing and has good aging stability.

Description

Technical Field

[0001] This invention relates to the field of sealant technology, and in particular to a de-alcoholized silicone sealant, its preparation method, and its application. Background Technology

[0002] Silicone sealant is a polymer material with polydimethylsiloxane as its main component. It possesses excellent weather resistance, high and low temperature resistance, aging resistance, chemical stability, electrical insulation, and excellent biocompatibility. It achieves long-term sealing by undergoing a cross-linking reaction with moisture in the air and curing into an elastic rubber body. Silicone sealants are mainly classified into acetic acid-free, alcohol-free, ketoxime-free, and acetone-free types. Among them, alcohol-free silicone sealants release alcohols during the curing process, exhibiting advantages such as low corrosivity and good environmental friendliness. They are widely used in bonding, sealing, and potting in fields such as electronics, new energy vehicles, and solar photovoltaic modules.

[0003] With the rapid development of industrial technology, the requirements for de-alcoholized silicone sealants are becoming increasingly stringent. These sealants not only need excellent sealing and bonding properties, but also rapid curing, high insulation, and high thermal conductivity. For example, in automated production lines, to improve production efficiency, sealants urgently need to achieve rapid, deep curing—that is, complete curing from surface dryness to the interior within a short time—to shorten process waiting time. Sealants used for electronic and electrical components must have extremely high electrical insulation, especially in humid environments, where their insulation resistance must remain at a high level to prevent leakage or short circuits. Furthermore, as the power density of electronic devices continues to increase, the heat generated by components during operation also increases. This necessitates that sealants possess excellent insulation properties while also having a certain degree of thermal conductivity to aid heat dissipation and ensure the long-term stable operation of components.

[0004] Traditional silicone sealants are typically based on α,ω-dihydroxypolydimethylsiloxane (107 sealant), a polymer combined with crosslinking agents, powder fillers, and catalysts. Researchers often modify or adjust the sealant components to improve certain properties. However, achieving a balance of multiple high performance characteristics in silicone sealants presents significant technical challenges. For example, improving the rapid curing performance of silicone sealants often sacrifices the product's storage stability, and introducing metal oxides to enhance the thermal conductivity of the sealant can reduce the material's electrical insulation properties to some extent.

[0005] Therefore, developing a de-alcoholized silicone sealant that can simultaneously meet the requirements of rapid deep curing, high humidity insulation resistance, good thermal conductivity, and stable storage has significant industrial application value. Summary of the Invention

[0006] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, the first objective of the present invention is to provide a dealcoholized silicone sealant. The second objective of the present invention is to provide a method for preparing this dealcoholized silicone sealant. The third objective of the present invention is to provide applications of this dealcoholized silicone sealant.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a dealcohol-type silicone sealant comprising the following raw materials in parts by weight: 100-200 parts of α,ω-dihydroxypolydimethylsiloxane, 150-400 parts of filler, 5-15 parts of crosslinking agent, 2-8 parts of catalyst, and 1-5 parts of coupling agent; wherein the filler comprises surface-modified aluminum hydroxide and calcium carbonate.

[0008] In the dealcohol-type silicone sealant raw material provided by this invention, aluminum hydroxide is an excellent flame retardant and thermally conductive filler with high volume resistivity. Surface-modified aluminum hydroxide greatly enhances its compatibility and dispersibility with the silicone matrix, constructing an effective thermally conductive network while maximizing the preservation of the matrix's excellent intrinsic insulation. The good dispersibility of the filler also reduces catalyst adsorption and deactivation, ensuring catalytic efficiency. Using surface-modified aluminum hydroxide in combination with calcium carbonate creates a synergistic effect, endowing the sealant with excellent thermal conductivity, adhesion, and mechanical properties.

[0009] Preferably, the weight ratio of the surface-modified aluminum hydroxide to calcium carbonate is (1~4):1; more preferably, the weight ratio of the surface-modified aluminum hydroxide to calcium carbonate is (1~3):1; even more preferably, the weight ratio of the surface-modified aluminum hydroxide to calcium carbonate is (1~2):1.

[0010] Preferably, the surface-modified aluminum hydroxide includes one or a combination of stearic acid-modified aluminum hydroxide and aminosilane-modified aluminum hydroxide.

[0011] Preferably, the median particle size (D50) of the stearic acid-modified aluminum hydroxide is 8 μm to 13 μm; more preferably, the D50 of the stearic acid-modified aluminum hydroxide is 9 μm to 12 μm.

[0012] Preferably, the median particle size (D50) of the aminosilane-modified aluminum hydroxide is 8 μm to 13 μm; more preferably, the D50 of the aminosilane-modified aluminum hydroxide is 9 μm to 12 μm.

[0013] Preferably, the α,ω-dihydroxypolydimethylsiloxane is present in 100-150 parts by weight; more preferably, the α,ω-dihydroxypolydimethylsiloxane is present in 100-130 parts by weight; and even more preferably, the α,ω-dihydroxypolydimethylsiloxane is present in 100-110 parts by weight.

[0014] Preferably, the filler has a weight of 150-300 parts; more preferably, the filler has a weight of 150-200 parts; and even more preferably, the filler has a weight of 160-180 parts.

[0015] Preferably, the crosslinking agent is present in 5 to 10 parts by weight; more preferably, the crosslinking agent is present in 5 to 7 parts by weight.

[0016] Preferably, the catalyst is 3 to 7 parts by weight; more preferably, the catalyst is 4 to 6 parts by weight.

[0017] Preferably, the coupling agent is present in 1 to 4 parts by weight; more preferably, the coupling agent is present in 1 to 2 parts by weight.

[0018] Preferably, the calcium carbonate includes one or a combination of two of heavy calcium carbonate and nano calcium carbonate; more preferably, the median particle size (D50) of the heavy calcium carbonate is 4 μm to 8 μm; even more preferably, the D50 of the heavy calcium carbonate is 5 μm to 7 μm.

[0019] Preferably, the specific surface area of ​​the nano-calcium carbonate is 15 m². 2 / g~25 m 2 / g; More preferably, the specific surface area of ​​nano-calcium carbonate is 17 m² / g; 2 / g~22 m 2 / g; More preferably, the specific surface area of ​​nano-calcium carbonate is 18 m² / g; 2 / g~20m 2 / g.

[0020] Preferably, the calcium carbonate is surface-modified calcium carbonate; more preferably, the surface-modified calcium carbonate is stearic acid-modified calcium carbonate; even more preferably, the stearic acid-modified calcium carbonate includes one or a combination of stearic acid-modified heavy calcium carbonate and stearic acid-modified nano calcium carbonate; even more preferably, the weight ratio of stearic acid-modified heavy calcium carbonate to stearic acid-modified nano calcium carbonate is (1~3):1.

[0021] In the de-alcoholized silicone sealant raw material provided by this invention, the combined use of heavy calcium carbonate and nano calcium carbonate as additives can effectively reduce costs. Furthermore, nano calcium carbonate can effectively improve the mechanical properties of the colloid and form a denser packing with other micron-sized fillers, which helps with heat transfer. In addition, it can also provide certain thixotropic properties, which is beneficial for dispensing operations.

[0022] Preferably, the filler further includes one or more of silica powder, zinc borate, alumina, silica, kaolin, talc, titanium dioxide, and zinc oxide.

[0023] Preferably, the viscosity of the α,ω-dihydroxypolydimethylsiloxane at 25°C is 500 cps to 50000 cps; more preferably, the viscosity of the α,ω-dihydroxypolydimethylsiloxane at 25°C includes one or more of 1000 cps, 1500 cps, 5000 cps, 20000 cps, and 50000 cps.

[0024] Preferably, the crosslinking agent includes one or more of methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, phenyltrimethoxysilane, and phenyltriethoxysilane.

[0025] More preferably, the crosslinking agent includes vinyltrimethoxysilane, and one or more of methyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, phenyltrimethoxysilane, and phenyltriethoxysilane. In addition to its crosslinking effect, vinyltrimethoxysilane also has a dehydration effect, effectively removing free water from the system and preventing free water from causing catalyst decomposition, the production of colored substances, and deactivation.

[0026] More preferably, the crosslinking agent is methyltrimethoxysilane and vinyltrimethoxysilane, and the weight ratio of methyltrimethoxysilane to vinyltrimethoxysilane is (1.5~3):1.

[0027] Preferably, the catalyst comprises a primary titanium complex and / or a secondary titanium complex; the primary titanium complex comprises one or more of bis(ethyl acetoacetate)titanate diisopropyl, bis(ethyl acetoacetate)titanate diisobutyl, tetraisopropyl titanate, and n-butyl titanate, and the secondary titanium complex is bis(ethyl acetoacetate-O1,O3)(1,3-propanediol--O,O')-titanium. Both the primary and secondary titanium complexes used in this invention belong to the titanate ester catalyst class. Compared with traditional organotin catalysts, titanate ester catalysts have higher activity and can significantly promote cross-linking reactions, especially within the colloid, effectively accelerating the diffusion of alcohol byproducts and subsequent cross-linking reactions, thereby achieving faster deep curing.

[0028] More preferably, the catalyst is diisobutyl bis(ethyl acetoacetate) titanate and di(ethyl acetoacetate-O1,O3)(1,3-propanediol--O,O')-titanium; even more preferably, the weight ratio of diisobutyl bis(ethyl acetoacetate) titanate and di(ethyl acetoacetate-O1,O3)(1,3-propanediol--O,O')-titanium is (2~5):1. This invention uses a combination of primary and secondary titanium complexes as a catalyst, which can ensure a certain curing depth while better controlling the curing speed and process. The catalyst compound system provided by this invention enables the system to quickly solidify, forming a stable thermally conductive / insulating three-dimensional network structure, and has advantages such as high catalytic efficiency, low dosage, and minimal negative impact on the electrical properties of the final product.

[0029] Preferably, the coupling agent comprises one or more of γ-aminopropyltrimethoxysilane (KH-540), γ-aminopropyltriethoxysilane (KH-550), γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560), N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane (KH-792), and 3-aminopropyltrimethoxysilane.

[0030] More preferably, the coupling agent is γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, and 3-aminopropyltrimethoxysilane; even more preferably, the weight ratio of γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, and 3-aminopropyltrimethoxysilane is (1~3):1:(1~3). The combined use of these three coupling agents can improve the adhesion performance between silicone sealant and different substrates, enabling the silicone sealant to have good adhesion performance to many substrates and allowing it to be applied to bonding and sealing in various scenarios.

[0031] Preferably, the de-alcoholized silicone sealant further includes 15-25 parts by weight of plasticizer; more preferably, the plasticizer includes one or more of dimethyl silicone oil, methyl vinyl silicone oil, and methyl phenyl silicone oil; even more preferably, the viscosity of the dimethyl silicone oil at 25°C is 300 cps to 500 cps.

[0032] Preferably, a dealcohol-based silicone sealant comprises the following raw materials in parts by weight: 80-200 parts of α,ω-dihydroxypolydimethylsiloxane, 150-400 parts of filler, 5-15 parts of crosslinking agent, 2-8 parts of catalyst, 1-5 parts of coupling agent, and 15-25 parts of plasticizer. More preferably, a dealcohol-based silicone sealant is composed of the following raw materials in parts by weight: 80-200 parts of α,ω-dihydroxypolydimethylsiloxane, 150-400 parts of filler, 5-15 parts of crosslinking agent, 2-8 parts of catalyst, 1-5 parts of coupling agent, and 15-25 parts of plasticizer.

[0033] Secondly, the present invention provides a method for preparing the de-alcoholized silicone sealant described in the first aspect of the present invention, comprising the following steps: S1: Mix α,ω-dihydroxypolydimethylsiloxane and filler to obtain the base adhesive; S2: The base adhesive is mixed and reacted with a crosslinking agent, a coupling agent and a catalyst to obtain the de-alcoholized silicone sealant.

[0034] Preferably, the mixing method in S1 is uniform mixing under vacuum, with a heating temperature of 110~140℃; more preferably, the mixing method in S1 is uniform mixing under vacuum in a mixer; even more preferably, the mixer in S1 is a planetary mixer; and even more preferably, the vacuum degree in S1 is ≤0.09MPa.

[0035] Preferably, the mixing time in S1 is 150~200 min.

[0036] Preferably, in S2, a crosslinking agent, a coupling agent, and a catalyst are added to the base adhesive in sequence, and the mixture is stirred and dispersed under vacuum after each addition, with the stirring and dispersion time being 20-30 min; more preferably, the vacuum degree in S2 is ≤0.09 MPa.

[0037] Preferably, the de-alcoholized silicone sealant obtained in S2 is packaged in packaging tubes; more preferably, the packaging tubes are high-density polyethylene (HDPE) packaging tubes.

[0038] Thirdly, the present invention provides the application of the dealcoholized silicone sealant described in the first aspect in the fields of electronics and electrical appliances, new energy vehicles, and solar photovoltaic modules.

[0039] The beneficial effects of this invention are: 1. In the dealcoholized silicone sealant raw material provided by this invention, the filler is surface-modified aluminum hydroxide, which greatly enhances the compatibility and dispersibility between aluminum hydroxide and the silicone matrix. While constructing an effective thermally conductive network, it maximizes the preservation of the excellent intrinsic insulation properties of the matrix. The good dispersibility of the filler also reduces the adsorption and deactivation of the catalyst, ensuring catalytic efficiency. The combined use of surface-modified aluminum hydroxide and calcium carbonate provides synergistic effects, endowing the sealant with excellent thermal conductivity, adhesion, and mechanical properties.

[0040] 2. The crosslinking agent, catalyst, and coupling agent in the de-alcoholized silicone sealant provided by this invention are all compounded systems. The crosslinking agent compound system removes free water from the system, preventing excessive viscosity caused by pre-crosslinking between free water and the crosslinking agent, and also preventing free water from decomposing the catalyst and producing colored substances. This results in a silicone sealant with good curing depth, insulation resistance, and aging stability. The catalyst compound system ensures a certain curing depth while better controlling the curing speed and process. The coupling agent compound system improves the adhesion between the silicone sealant and different substrates, giving the silicone sealant good adhesion to many substrates and enabling its application in various bonding and sealing scenarios.

[0041] 3. The preparation method of the dealcoholized silicone sealant provided by the present invention is simple in process and easy to operate. The raw materials used are inexpensive and readily available. The equipment requirements are low and it is suitable for conventional equipment, reducing the dependence on special equipment and making it suitable for large-scale industrial production.

[0042] 4. The components of the de-alcoholized silicone sealant provided by this invention have synergistic effects, and the prepared de-alcoholized silicone sealant has good rapid curing performance, thermal conductivity, electrical insulation performance and adhesive performance. It is not prone to yellowing and has good aging stability, and can be well applied in the fields of electronics, electrical appliances, new energy vehicles, solar photovoltaic modules and other fields. Attached Figure Description

[0043] Figure 1 The curing depth curve of the de-alcoholized silicone sealant prepared in Example 1 is shown. Detailed Implementation

[0044] To enable those skilled in the art to more clearly understand this application, the present invention will be further described in detail below with reference to embodiments. However, it should be understood that the following embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. Furthermore, to better illustrate the present invention, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that the present invention can be implemented even without certain specific details. In some embodiments, raw materials, methods, and means well known to those skilled in the art are not described in detail in order to highlight the main points of the present invention. In the description of the present invention, it should be noted that, where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0045] The following are some of the sources and specifications of the raw materials used in this application. The raw materials used in the preparation examples and embodiments of this application can all be obtained commercially, including but not limited to the following models and manufacturers of raw materials. Raw materials with equivalent performance can also be used: Aminosilane-modified aluminum hydroxide: D50 of 8μm~13μm, purchased from Guangdong Jingge New Materials Co., Ltd. Stearic acid modified aluminum hydroxide: D50 is 8μm~13μm, purchased from Guangzhou Zhengguan Polymer Materials Co., Ltd. Stearic acid modified heavy calcium carbonate: D50 is 5μm~7μm, Guangxi Hezhou Kelong Powder Co., Ltd.; Stearic acid modified nano-calcium carbonate: specific surface area of ​​17m² 2 / g~22m 2 / g, Guangxi Huana New Materials Co., Ltd.; α,ω-Dihydroxypolydimethylsiloxane: viscosity 5000cps, 25℃, Jiangxi Lanxing Xinghuo Organosilicon Co., Ltd. γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane and 3-aminopropyltrimethoxysilane, CAS numbers 919-30-2, 1760-24-3 and 13822-56-5 respectively, Hubei Jianghan New Material Co., Ltd.; Diisobutyl bis(ethyl acetoacetate) titanate, CAS No. 83877-91-2, Guangzhou Jianyi Chemical Import & Export Co., Ltd.; Di(ethyl acetoacetate-O1,O3)(1,3-propanediol--O,O')-titanium, CAS No.: 36497-11-7; Dimethyl silicone oil (viscosity 350 cps, 25℃), Dow Corning (China) Co., Ltd.

[0046] Example 1 An alcohol-free silicone sealant, by weight, comprises 100 parts of α,ω-dihydroxypolydimethylsiloxane with a viscosity of 5000 cps at 25°C, 110 parts of aminosilane-modified aluminum hydroxide, 20 parts of stearic acid-modified heavy calcium carbonate (particle size D50 of 5~7μm), 40 parts of stearic acid-modified nano-calcium carbonate, 6 parts of crosslinking agent, 5 parts of catalyst, 1.5 parts of coupling agent, and 15 parts of plasticizer; The crosslinking agent is methyltrimethoxysilane and vinyltrimethoxysilane in a weight ratio of 3:1; The catalyst is diisobutyl bis(ethyl acetoacetate) titanate and di(ethyl acetoacetate-O1,O3)(1,3-propanediol--O,O')-titanium in a weight ratio of 7:3. The coupling agent is γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane and 3-aminopropyltrimethoxysilane in a weight ratio of 2:1:2; The plasticizer is dimethyl silicone oil with a viscosity of 350 cps at 25°C.

[0047] The above-mentioned dealcoholized silicone sealant was prepared using the following method: S1: Add α,ω-dihydroxypolydimethylsiloxane and aminosilane-modified aluminum hydroxide, stearic acid-modified heavy calcium carbonate, and stearic acid-modified nano calcium carbonate to a planetary power mixer, evacuate to a vacuum degree ≤0.09MPa, heat to 110℃~130℃ and stir for 3h, then circulate cold water to cool it to below 40℃ to obtain the base adhesive; S2: Add crosslinking agent, coupling agent, plasticizer and catalyst to the base adhesive in sequence. Keep the vacuum (vacuum degree ≤0.09Mpa) and stir for 30 min at each step. After stirring evenly, discharge the material to obtain the de-alcoholized silicone sealant.

[0048] Example 2 The difference between this embodiment and Example 1 is that this embodiment uses stearic acid-modified aluminum hydroxide instead of aminosilane-modified aluminum hydroxide in Example 1. All other aspects are the same as in Example 1.

[0049] Example 3 The difference between this embodiment and Embodiment 1 is that in this embodiment, the amount of aminosilane-modified aluminum hydroxide is 130 parts, the amount of stearic acid-modified heavy calcium carbonate is 14 parts, and the amount of stearic acid-modified nano calcium carbonate is 26 parts. All other parts are the same as in Embodiment 1.

[0050] Example 4 The difference between this embodiment and Example 1 is that the catalyst in this embodiment is 6.5 parts (diisobutyl acetoacetate titanate and di(acetoacetate-O1,O3)(1,3-propanediol--O,O')-titanium in a weight ratio of 7:3), and the rest is the same as in Example 1.

[0051] Example 5 The difference between this embodiment and Embodiment 1 is that no plasticizer is added in this embodiment, and 115 parts of α,ω-dihydroxypolydimethylsiloxane with a viscosity of 5000 cps at 25°C are used. All other parts are the same as in Embodiment 1.

[0052] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 does not add aminosilane-modified aluminum hydroxide, but adds 85 parts of stearic acid-modified heavy calcium carbonate and 85 parts of stearic acid-modified nano calcium carbonate. All other aspects are the same as in Example 1.

[0053] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 adds 170 parts of aminosilane-modified aluminum hydroxide, and does not add stearic acid-modified heavy calcium carbonate or stearic acid-modified nano calcium carbonate. All other aspects are the same as in Example 1.

[0054] Comparative Example 3 The difference between this comparative example and Example 1 is that this comparative example adds 60 parts of stearic acid-modified heavy calcium carbonate and does not add stearic acid-modified nano calcium carbonate; otherwise, it is the same as Example 1.

[0055] Comparative Example 4 The difference between this comparative example and Example 1 is that the aluminum hydroxide added in this comparative example was not modified with aminosilane, while the rest is the same as in Example 1.

[0056] Comparative Example 5 The difference between this comparative example and Example 1 is that this comparative example adds 16 parts of crosslinking agent (methyltrimethoxysilane and vinyltrimethoxysilane in a weight ratio of 3:1), while the rest are the same as in Example 1.

[0057] Comparative Example 6 The difference between this comparative example and Example 1 is that the crosslinking agent added in this comparative example is 6 parts (methyltrimethoxysilane and phenyltrimethoxysilane in a weight ratio of 3:1), and the rest is the same as in Example 1.

[0058] Comparative Example 7 The difference between this comparative example and Example 1 is that the coupling agent added in this comparative example is 1.5 parts (KH-550 and KH-560 in a weight ratio of 2:1), and the rest is the same as in Example 1.

[0059] Comparative Example 8 The difference between this comparative example and Example 1 is that 5 parts of catalyst were added in this comparative example. The catalyst was diisobutyl bis(ethyl acetoacetate) titanate. All other aspects were the same as in Example 1.

[0060] Comparative Example 9 The difference between this comparative example and Example 1 is that 5 parts of catalyst were added in this comparative example. The catalyst was di(ethyl acetoacetate-O1,O3)(1,3-propanediol--O,O')-titanium.

[0061] Performance testing The properties of the alcohol-free silicone sealants prepared in Examples 1-5 and Comparative Examples 1-9 were tested. The test items and methods are as follows: (1) Determination of surface drying time: The test was carried out in accordance with GB / T 13477.5-2002. Under the conditions of temperature 25±2℃ and relative humidity 50±5%, the de-alcoholized silicone sealant prepared in Examples 1-5 and Comparative Examples 1-9 was extruded onto the surface of the plastic film, with a thickness of about 2-3 mm and a length >100 mm. Every 1 minute, the adhesive layer was touched lightly with a finger until the adhesive no longer stuck to the finger. The time from extrusion to no longer sticking to the finger was recorded as the surface drying time. (2) Tensile strength test: The de-alcoholized silicone sealant prepared in Examples 1-5 and Comparative Examples 1-9 were used to prepare tensile samples with a thickness of 2 mm on polytetrafluoroethylene plates. After curing at 25℃±2℃ for 7 days, the samples were tested according to GB / T528-2009. (3) Aging stability test: The de-alcoholized silicone sealant prepared in Examples 1-5 and Comparative Examples 1-9 was sealed in 300mL plastic tubes and then placed in a forced-air drying oven at 70℃±2℃ for 7 days. After 7 days, the yellowing of the sealant was observed. At the same time, the surface drying time of the sealant after 7 days of aging at 70℃ was tested according to the test method of surface drying time. (4) Curing depth test: The test was conducted according to Method 2 of GB / T 32369-2015: the wedge groove method. Starting from the lowest point of the wedge groove, the de-alcoholized silicone sealant prepared in Examples 1-5 and Comparative Examples 1-9 was applied to completely fill the groove and prevent air from entering. The sealant was placed in an environment of 23℃±2℃ and 50%±5% relative humidity. When the degree of curing needed to be measured at any time during the curing process, the sealant was peeled off starting from the highest point of the wedge groove until uncured sealant was observed adhering to the groove. The distance from the highest point of the groove to this point was measured, and the curing depth was calculated using the formula. (5) Insulation resistance test: The test was conducted in accordance with GB / T 40720-2021. The test voltage was 500V and the test time was 10s. The standard test mold was used. The thickness of the de-alcoholized silicone sealant samples prepared in Examples 1-5 and Comparative Examples 1-9 was 8 mm. (6) Thermal conductivity test: The test was conducted in accordance with GB / T 29313-2012. The surfaces of the de-alcoholized silicone sealant samples prepared in Examples 1-5 and Comparative Examples 1-9 were smooth and glossy, and the thickness was 2 mm. (7) Adhesion performance test: The surface of the bonding substrate was cleaned with alcohol. The bonding substrates selected were polycarbonate (PC), polyvinyl chloride (PVC), polyterephthalic acid (PET), printed circuit board (PCB), three-series aluminum alloy, 6061 aluminum alloy and 304 stainless steel. The de-alcoholized silicone sealant prepared in Examples 1-5 and Comparative Examples 1-9 was applied to the surface of the bonding substrate to obtain a 1.5 mm thick adhesive strip. After curing for 7 days at 25℃±2℃ and relative humidity of 50±5%, the bonding performance was tested according to GB 16776-2005. The test results are shown in Tables 1 and 2: Table 1 Performance test results of the silicone sealants prepared in Examples 1-5 and Comparative Examples 1-9

[0062] Table 2. Adhesion performance test results of the silicone sealants prepared in Examples 1-5 and Comparative Examples 1-9 on various substrates.

[0063] As shown in Tables 1 and 2, the silicone sealants prepared in Examples 1 to 5 of this invention have good rapid curing performance, electrical insulation performance, thermal conductivity performance and mechanical properties. They have good adhesion performance to substrates such as PC, PVC, ternary aluminum alloy, 6061 aluminum alloy and 304 stainless steel, and can achieve good bonding and sealing effect. Moreover, the surface drying time is moderate and the aging stability is good.

[0064] Comparing Comparative Example 1 with Example 1, it can be seen that the filler in Comparative Example 1 did not contain aminosilane-modified aluminum hydroxide, which significantly reduced the thermal conductivity and insulation properties of the silicone sealant prepared in Comparative Example 1. Comparing Comparative Example 2 with Example 1, it can be seen that the filler in Comparative Example 2 did not contain stearic acid-modified heavy calcium carbonate or stearic acid-modified nano calcium carbonate. Although the thermal conductivity of the silicone sealant prepared in Comparative Example 2 was slightly improved, the tensile strength decreased significantly, and the adhesion to 6061 aluminum alloy and 304 stainless steel was poor. Comparing Comparative Example 3 with Example 1, it can be seen that the filler in Comparative Example 3 only contained aminosilane-modified aluminum hydroxide and stearic acid-modified heavy calcium carbonate, without the addition of stearic acid-modified nano calcium carbonate. The silicone sealant prepared in Comparative Example 3 had a slower surface drying time, lower tensile strength, and lower curing depth. This is because heavy calcium carbonate has a large particle size, low activity, and a slow cross-linking reaction. The cross-linking reaction is mostly concentrated on the surface, resulting in slow internal curing. Therefore, the surface drying time is long and the curing depth is low. Furthermore, heavy calcium carbonate only plays a basic filler role in the silicone sealant system, with a low reinforcing effect, resulting in low tensile strength. Comparing Comparative Example 4 and Example 1, it can be seen that the aluminum hydroxide added in Comparative Example 4 was not modified with aminosilane. Unmodified aluminum hydroxide has high polarity, poor dispersibility, and weak bonding with 107 adhesive, only playing a simple filler role. Therefore, the prepared silicone sealant has low tensile strength. In addition, due to the uneven dispersion of unmodified aluminum hydroxide, its contact thermal resistance at the colloid interface is also greater, resulting in poorer thermal conductivity of the silicone sealant. Furthermore, the low activity and slow cross-linking reaction of unmodified aluminum hydroxide lead to a longer surface drying time and shallower curing depth in the prepared silicone sealant.

[0065] Therefore, in this embodiment of the invention, the filler is surface-modified aluminum hydroxide, stearic acid-modified heavy calcium carbonate, and stearic acid-modified nano calcium carbonate. The three are compounded and synergistically enhanced, giving the silicone sealant system good compatibility and dispersibility, and endowing the sealant with excellent thermal conductivity, adhesion and mechanical properties.

[0066] Comparing Comparative Example 5 with Example 1, it can be seen that the excessive crosslinking agent content in Comparative Example 5 resulted in an excessively high crosslinking density, making it difficult for moisture to penetrate deep into the vulcanization crosslinking layer. This led to a lower curing depth of the prepared silicone sealant. Furthermore, the crosslinking agent itself is conductive, and excessive addition also reduced the insulation performance of the silicone sealant. Comparing Comparative Example 6 with Example 1, it can be seen that the crosslinking agent in Comparative Example 6 did not contain vinyltrimethoxysilane and therefore lacked dehydration properties. This resulted in the presence of free water in the silicone sealant system. The free water reacted with the crosslinking agent to produce pre-crosslinking, increasing viscosity and accelerating surface drying time. Moreover, the free water caused the decomposition of the organotitanate catalyst and the production of colored substances. With prolonged time, the catalyst gradually deactivated, leading to a sharp increase in surface drying time or even failure to cure after aging of the silicone sealant. Therefore, the silicone sealant prepared in Comparative Example 6 exhibited slow surface drying and yellowing after aging at 70℃ for 7 days.

[0067] Therefore, the crosslinking agent compound system used in the embodiments of the present invention can remove free water in the system, avoid excessive viscosity caused by pre-crosslinking of free water and crosslinking agent, and also avoid free water causing catalyst decomposition and the generation of colored substances, so that the prepared silicone sealant has good curing depth, insulation resistance and aging stability.

[0068] Comparing Comparative Example 7 with Example 1, it can be seen that, because the coupling agent in Comparative Example 7 did not include KH-792 and 3-aminopropyltrimethoxysilane, the silicone sealant prepared in Comparative Example 7 exhibited interfacial damage with PVC, 6061 aluminum alloy, and 304 stainless steel substrates. This indicates that the adhesion performance of Comparative Example 7 is significantly worse than that of Example 1. Therefore, the coupling agent compound system (KH-550, KH-792, and 3-aminopropyltrimethoxysilane) used in the embodiments of the present invention can improve the adhesion performance of silicone sealant to different substrates, enabling the silicone sealant to have good adhesion performance to many substrates and to be applied to bonding and sealing in various scenarios.

[0069] Comparing Comparative Example 8 with Example 1, it can be seen that, because Comparative Example 8 only used bis(ethyl acetoacetate) titanate diisobutyl ester as a catalyst, the surface drying time of the silicone sealant prepared in Comparative Example 8 was faster than that in Example 1, the curing depth was lower, and yellowing occurred in the aging stability test. This is because bis(ethyl acetoacetate) titanate diisobutyl ester is a primary titanium complex with high catalytic activity, thus the surface drying time of the prepared silicone sealant is shorter. However, the excessively fast catalysis and crosslinking speed also affected the penetration of moisture, resulting in a lower curing depth. On the other hand, the unstable Ti center of bis(ethyl acetoacetate) titanate easily decomposes and catalyzes the oxidation of methyl groups on the side chains of the silicone polymer, generating chromophores and causing yellowing. Comparing Comparative Example 9 with Example 1, it can be seen that, because Comparative Example 9 only used di(ethyl acetoacetate-O1,O3)(1,3-propanediol--O,O')-titanium as a catalyst, the surface drying time of the silicone sealant prepared in Comparative Example 9 was slower, and the surface drying time after aging was also slower. This is because di(ethyl acetoacetate-O1,O3)(1,3-propanediol--O,O')-titanium is a secondary titanium complex with lower activity, thus prolonging the surface drying time. Furthermore, the insulation resistance performance of Comparative Examples 8 and 9 is inferior to that of Example 1, indicating that the combined use of primary and secondary titanium complexes can improve the insulation resistance performance of silicone sealant. This is because the combined use of primary and secondary titanium complexes optimizes the cross-linking network and reduces conductive channels. The primary titanium complex has high activity and can quickly build the cross-linking network framework, while the secondary titanium complex has lower activity but stronger stability, filling the network gaps formed by the primary titanium cross-linking, making the overall cross-linking structure more uniform and dense. This non-porous, defect-free network avoids the problem of external moisture and impurities intruding and forming conductive channels, thereby improving insulation resistance performance.

[0070] Therefore, the silicone sealant prepared by the catalyst compound system (compound of primary titanium complex and secondary titanium complex) used in the embodiments of the present invention has a moderate surface drying time, which can ensure a certain curing depth while better controlling the curing speed and curing process.

[0071] In addition, the curing depth of the de-alcoholized silicone sealant prepared in Example 1 was tested using a curing depth test method (temperature 25℃, relative humidity 55%) at curing times of 1d, 2d, 3d, 4d, 5d, 6d, and 7d, and curing depth curves were plotted. The curing curves are shown below. Figure 1 As shown. By Figure 1 It can be seen that the de-alcoholized silicone sealant prepared in Example 1 has a high curing depth, reaching 7.12 mm after 7 days of curing.

[0072] In summary, the components of the de-alcoholized silicone sealant provided in this embodiment of the invention work synergistically to produce a de-alcoholized silicone sealant that combines excellent rapid curing performance, thermal conductivity, electrical insulation performance, and adhesive performance. It is also less prone to yellowing and has good aging stability, making it suitable for applications in fields such as electronics, new energy vehicles, and solar photovoltaic modules.

[0073] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A de-alcoholized silicone sealant, characterized in that, The raw materials include the following parts by weight: 80-200 parts of α,ω-dihydroxypolydimethylsiloxane, 150-400 parts of filler, 5-15 parts of crosslinking agent, 2-8 parts of catalyst, and 1-5 parts of coupling agent; the filler includes surface-modified aluminum hydroxide and calcium carbonate.

2. The de-alcoholized silicone sealant according to claim 1, characterized in that, The viscosity of the α,ω-dihydroxypolydimethylsiloxane at 25°C is 500cps~50000cps.

3. The de-alcoholized silicone sealant according to claim 1, characterized in that, The calcium carbonate includes one or a combination of two of heavy calcium carbonate and nano calcium carbonate.

4. The de-alcoholized silicone sealant according to claim 1, characterized in that, The calcium carbonate is surface-modified calcium carbonate.

5. The de-alcoholized silicone sealant according to claim 1, characterized in that, The filler also includes one or more of the following: silica powder, zinc borate, alumina, silica, kaolin, talc, titanium dioxide, and zinc oxide.

6. The de-alcoholized silicone sealant according to claim 1, characterized in that, The crosslinking agent includes one or more of methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, phenyltrimethoxysilane, and phenyltriethoxysilane.

7. The dealcohol-type silicone sealant according to claim 1, characterized in that, The catalyst comprises a primary titanium complex and / or a secondary titanium complex; the primary titanium complex comprises one or more of bis(ethyl acetoacetate) titanate diisopropyl bis(ethyl acetoacetate) titanate diisobutyl bis(ethyl acetoacetate) titanate, tetraisopropyl titanate, and n-butyl titanate; and the secondary titanium complex is bis(ethyl acetoacetate-O1,O3)(1,3-propanediol--O,O')-titanium.

8. The de-alcoholized silicone sealant according to claim 1, characterized in that, The coupling agent includes one or more of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, and 3-aminopropyltrimethoxysilane.

9. The method for preparing the dealcohol-type silicone sealant according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1: Mix α,ω-dihydroxypolydimethylsiloxane and filler to obtain the base adhesive; S2: The base adhesive is mixed and reacted with a crosslinking agent, a coupling agent and a catalyst to obtain the de-alcoholized silicone sealant.

10. The application of the de-alcoholized silicone sealant according to any one of claims 1 to 8 in the fields of electronics and electrical appliances, new energy vehicles, and solar photovoltaic modules.

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