A kind of silicone weather-resistant sealant and preparation method thereof

Abstract

The present application provides a silicone weatherproof sealant and a preparation method thereof, the silicone weatherproof sealant comprising the following raw materials in parts by mass: 100 parts of hydroxyl-terminated polydimethylsiloxane, 5-15 parts of polyether-modified silane coupling agent, 10-20 parts of aromatic silane coupling agent, 2-10 parts of alkyl silane coupling agent, 1-10 parts of plasticizer, 40-60 parts of filler, and 0.1-2 parts of catalyst. The silicone weatherproof sealant uses hydroxyl-terminated polydimethylsiloxane as the main material and uses polyether-modified silane coupling agent, aromatic silane coupling agent, and alkyl silane coupling agent as cross-linking agents. By utilizing the different molecular structures, hydrolysis rate differences, and molecular migration capabilities of the three, a sealant with a rigid exterior and flexible interior structure can be obtained, thereby obtaining a silicone weatherproof sealant having good aging resistance and fatigue resistance.

Description

Technical Field

[0001] The present application relates to the technical field of silicone sealants, and in particular to a silicone weather-resistant sealant and a preparation method thereof. Background Art

[0002] Silicone sealant, a widely used elastic sealing material in buildings, curtain walls, doors and windows, and industrial assembly, has become one of the mainstream sealant systems due to its excellent weather resistance, UV aging resistance, low-temperature flexibility, and long-term stability. Its main component is hydroxyl-terminated polydimethylsiloxane. By adding appropriate amounts of crosslinking agents, catalysts, and fillers, it forms a three-dimensional crosslinked network through moisture curing, achieving sealing and stress buffering effects on joints, interfaces, and structures.

[0003] To further enhance the overall performance of silicone sealants, particularly their weather resistance, deformation recovery, and service life, various physical and chemical modification methods are widely used in the prior art. Typical approaches include introducing UV-resistant phenyl silicone oils, enhancing flexibility with polyether silicone oils, or using multifunctional silanes as crosslinking agents. These components can improve the sealant's aging resistance, stress-buffering properties, and bond durability to varying degrees.

[0004] However, the above-mentioned modification methods generally have the following problems: for example, polyether silicone oil and phenyl silicone oil are only incorporated into the system by physical mixing, and do not participate in the main chain cross-linking during the curing process. They are prone to migration, precipitation or interface fatigue during use, resulting in a decrease in sealing performance; the cross-linking agents in existing sealants are generally evenly distributed, and form an equal-density network structure after curing, which makes it difficult to take into account multiple performance requirements such as surface weather protection, internal flexible deformation and structural support, resulting in the material showing problems such as bonding failure, fatigue cracking or surface aging under long-term exposure, high displacement or complex environments.

[0005] Patent CN119080822A discloses a modified alkoxy crosslinker, a dealcoholized silicone sealant, and a preparation method thereof. The modified alkoxy crosslinker is a trimethoxysilane-terminated polyurethane oligomer that incorporates highly reactive groups to accelerate the cure rate of the silicone sealant. The dealcoholized silicone sealant is prepared by combining the modified alkoxy crosslinker with α,ω-dihydroxy polysiloxane, an inorganic filler, a complex crosslinking agent, and a catalyst in an alcohol-based system to produce a silicone weathering sealant. This silicone weathering sealant exhibits excellent weather resistance and mechanical properties, high displacement capacity, and a fast surface drying rate. The small alcohol molecules removed during vulcanization are environmentally friendly and non-corrosive to most building materials. The process is simple and suitable for large-scale production.

[0006] The dealcoholized silicone sealant can accelerate the curing speed of the silicone sealant by using a compound cross-linking agent, and improve the weather resistance and mechanical properties of the silicone weather-resistant sealant. The corresponding effect is mainly achieved by a homemade cross-linking agent, and the improvement of the aging resistance of the sealant is limited.

[0007] Therefore, there is an urgent need to provide a silicone weather-resistant sealant with good aging resistance, which is suitable for application scenarios with long-term exposure and harsh weathering requirements. Summary of the Invention

[0008] The present application provides a silicone weather-resistant sealant and a preparation method thereof, which uses a variety of silane coupling agents as cross-linking agents and utilizes the reaction paths of different silane coupling agents to obtain sealants with different internal and external cross-linking structures, thereby having aging resistance and fatigue resistance.

[0009] In a first aspect, the present application provides a silicone weather-resistant sealant comprising the following raw materials in parts by weight:

[0010] 100 parts of hydroxyl-terminated polydimethylsiloxane, 5-15 parts of polyether-modified silane coupling agent, 10-20 parts of aromatic silane coupling agent, 2-10 parts of alkyl silane coupling agent, 1-10 parts of plasticizer, 40-60 parts of filler, 0.1-2 parts of catalyst.

[0011] According to the present application, the silicone weather-resistant sealant uses hydroxyl-terminated polydimethylsiloxane as the main material. By using a polyether-modified silane coupling agent, an aromatic silane coupling agent and an alkyl silane coupling agent as cross-linking agents, and utilizing the different molecular structures, hydrolysis rate differences and molecular migration capabilities of the three, a sealant with a rigid outer layer and a flexible inner layer can be obtained. The aromatic silane coupling agent is mainly cross-linked in the outer layer to form a rigid outer shell, and the polyether-modified silane coupling agent is mainly cross-linked in the inner layer to form a flexible inner core. Since the aromatic group in the rigid outer shell has good hydrophobicity and ultraviolet absorption ability, and the flexible inner core is conducive to dispersing stress, the silicone weather-resistant sealant has good aging resistance and fatigue resistance.

[0012] Specifically, the inventors discovered that in related art, single-component silicone weatherproof sealants typically use a single crosslinker for moisture curing. While this approach forms a basic three-dimensional crosslinked network structure, it suffers from issues such as a single crosslink density, severe structural rigidity, insufficient flexibility, and uncontrollable crosslinking behavior. This can easily lead to defects such as rapid surface curing, delayed internal curing, and even hollow, false curing. This can cause the sealant to fracture, fatigue, or lose adhesion under complex stress conditions such as high-frequency displacement or thermal expansion and contraction. Furthermore, a single crosslinker system struggles to achieve a comprehensive performance balance, including UV resistance, deformation recovery, and long-term bond reliability. Based on this, the inventors simultaneously added a polyether-modified silane coupling agent, an aromatic silane coupling agent, and an alkyl silane coupling agent to the sealant system, wherein the polyether-modified silane coupling agent molecule has a hydrolyzable silane group at one or both ends and a flexible polyether segment in the middle. Since the molecular weight of the polyether-modified silane coupling agent is relatively higher and the polyether segment has a certain electron-donating effect, the electrophilicity of the silicon atom is reduced, making the hydrolysis and condensation reaction of the polyether-modified silane coupling agent relatively slow. At the same time, the polyether segment has good hydrophilicity and can complex with water and penetrate into the sealant in the direction of water penetration, so that the polyether-modified silane coupling agent can be cross-linked inside the sealant to form a flexible buffer network. At the same time, the polyether-modified silane coupling agent can also promote the diffusion of moisture inside the sealant, promote the moisture curing reaction inside the sealant, and migrate to the polyether-modified silicone inside. The polyether chain segments in the cross-linked products of the alkyl silane coupling agent can also improve the bonding performance of the sealant. Compared with the aromatic silane coupling agent, the alkyl silane coupling agent has higher hydrolysis and condensation activity, and can react quickly on the surface of the sealant to form a limiting layer, thereby increasing the surface drying speed of the sealant. At the same time, by reducing the amount of alkyl silane coupling agent used in the system and reducing the cross-linking density on the surface in the early stage of curing, it can promote the penetration of moisture into the interior of the sealant. As the moisture curing reaction proceeds, the aromatic silane coupling agent undergoes sufficient hydrolysis and condensation reaction, which can cooperate with the alkyl silane coupling agent to make the outer layer of the sealant have a higher cross-linking density. At the same time, the cross-linked product of the aromatic silane coupling agent contains aromatic rings, which can partially absorb ultraviolet energy and slow down the degradation of the main chain and the inner polyether chain segments. The strong hydrophobicity of the aromatic rings combined with the high cross-linking degree can effectively improve the aging resistance of the sealant.

[0013] It is worth noting that in the related art, polyether silicone oil and aromatic silicone oil are added to the sealant to improve the flexibility and aging resistance of the sealant. However, the problem is that they are all non-reactive components and there are problems of migration and precipitation leading to aging. In this application, the polyether segments and aromatic groups are grafted and cross-linked in the network through hydrolysis and condensation reactions, and the above-mentioned migration and precipitation problems do not exist, which can play a long-term anti-fatigue and anti-aging role.

[0014] It should also be understood that the different internal and external crosslinking structures of the sealant in this application are formed during the moisture absorption and curing process by utilizing the molecular structures, differential hydrolysis rates, and molecular migration capabilities of three different silane coupling agents. Specifically, the inner layer of the sealant primarily uses a polyether-modified silane coupling agent as a crosslinker, while the outer layer primarily uses an aromatic silane coupling agent. The alkyl silane coupling agents in both the inner and outer layers synergistically increase the crosslink density of the sealant (this does not preclude the inner layer from including an aromatic silane coupling agent, and the outer layer from including a polyether-modified silane coupling agent). In addition to the main material and crosslinking agent, the sealant also includes a plasticizer, a filler, and a catalyst. The plasticizer primarily improves the sealant's processability and promotes water penetration of the polyether-modified silane coupling agent. The filler cooperates with the crosslinking network to enhance the sealant's strength. The catalyst increases the reaction rate between the crosslinker and the main material, thereby shortening the processing cycle.

[0015] In some embodiments, the end-capping group of the polyether-modified silane coupling agent is dimethoxysilane.

[0016] In some of the above embodiments, the inventors found that when a polyether-modified silane coupling agent with a terminal group of dimethoxysilane is used, the aging resistance and fatigue resistance of the silicone weathering sealant are better; the reason may be that the hydrolysis and condensation activity of the dimethoxysilane-terminated polyether-modified silane coupling agent is weaker than that of trimethoxysilane, and it is easier to migrate to the interior of the sealant with water penetration, thereby making the content of the polyether-modified silane coupling agent in the outer layer of the sealant lower and the content of the polyether-modified silane coupling agent in the inner layer higher, so that the outer layer of the sealant has better UV resistance and hydrophobicity, which is more conducive to reducing the degradation of the main chain and the internal polyether chain segments and improving the aging resistance; at the same time, since dimethoxysilane has only two reaction sites that can be hydrolyzed and condensed, the cross-linking density inside the sealant can be appropriately reduced, thereby further improving the flexibility inside the sealant, more effectively dispersing stress, and further improving the fatigue resistance of the sealant.

[0017] In some embodiments, the polyether-modified silane coupling agent is Kaneka SAX015. Based on the above embodiment, the polyether-modified silane coupling agent also has a lower molecular weight and is more likely to migrate into the sealant along the direction of water penetration, further improving the aging resistance and fatigue resistance of the sealant.

[0018] In some embodiments, the aromatic silane coupling agent includes trimethoxy(4-fluorophenyl)silane.

[0019] In some of the above embodiments, the use of trimethoxy (4-fluorophenyl) silane as an aromatic silane coupling agent can further improve the aging resistance of the silicone weatherproof sealant; the reason may be that trimethoxy (4-fluorophenyl) silane has three methoxy groups that can undergo hydrolysis and condensation, which is beneficial to improving the cross-linking density of the sealant. At the same time, the fluorophenyl group can be retained in the cross-linking network of trimethoxy (4-fluorophenyl) silane and hydroxyl-terminated polydimethylsiloxane by dehydration condensation. Since the lone pair of electrons of the fluorine atom on the benzene ring can produce a conjugated effect with the π electron cloud on the benzene ring to form a p-π conjugated electron cloud, it has better ultraviolet absorption ability than ordinary aromatic rings, and the F atom can further reduce the surface energy of the outer layer of the sealant, further reducing the hydrophobicity of the outer layer of the sealant, thereby effectively reducing the destructive degradation effect of moisture and ultraviolet light on the sealant, thereby further improving the aging resistance of the silicone weatherproof sealant.

[0020] In some embodiments, the aromatic silane coupling agent further comprises trimethoxy(4-methoxyphenyl)silane, and the mass ratio of the trimethoxy(4-fluorophenyl)silane to the trimethoxy(4-methoxyphenyl)silane is 1:2-4.

[0021] In some of the above embodiments, the inventors found that when a certain proportion of trimethoxy (4-fluorophenyl) silane and trimethoxy (4-methoxyphenyl) silane is used as an aromatic silane coupling agent, the aging resistance and fatigue resistance of the silicone weathering sealant are better; the reason may be that although the fluorophenyl group retained by cross-linking and curing with trimethoxy (4-fluorophenyl) silane can further improve the aging resistance of the sealant, the fluorine atom on the benzene ring is a strong electron-withdrawing group, which will reduce the electron cloud density on the benzene ring, thereby increasing the silicon atom located in the para position of the benzene ring. The electrophilicity of the ions increases the hydrolysis and condensation activity of the methoxy groups, which may lead to an excessively fast crosslinking speed of the outer layer, affecting the penetration of water into the interior of the sealant during the curing process, resulting in incomplete crosslinking and curing of the sealant, thereby adversely affecting the performance of the sealant. The inventors have found that adding a certain amount of trimethoxy (4-methoxyphenyl) silane can effectively improve the above-mentioned problems. The methoxy group connected to the benzene ring, in which the oxygen atom has a certain electron-withdrawing effect, also has a p-π conjugation effect similar to that of the F atom. The higher electronegativity of the oxygen atom will reduce The density of the electron cloud on the benzene ring, but the p-π conjugation effect will increase the electron cloud density on the benzene ring, and the electronegativity of the oxygen atom is weaker than that of the F atom, so the overall electron-pushing effect will increase the electron cloud density on the benzene ring, thereby reducing the electrophilicity of the silicon atom on the para position. Therefore, the hydrolysis and condensation activity of trimethoxy (4-methoxyphenyl) silane is relatively lower, which will reduce the cross-linking and curing speed of the outer layer, which is beneficial to the penetration of moisture into the interior of the sealant during the curing process and promote the internal cross-linking reaction. On the other hand, trimethoxy (4-methoxyphenyl) silane retains The lone pair of electrons of the oxygen atom on the benzene ring will also form p-π conjugation with the π electron cloud on the benzene ring. The p-π conjugated electron cloud can also further improve the ultraviolet absorption ability of the outer layer; the trimethoxy (4-fluorophenyl) silane with a faster reaction rate is easier to cross-link and cure to the outer layer of the sealant, and can also effectively exert its hydrophobic effect; therefore, when a certain proportion of trimethoxy (4-fluorophenyl) silane and trimethoxy (4-methoxyphenyl) silane is used as an aromatic silane coupling agent, the aging resistance and fatigue resistance of the silicone weathering sealant are better.

[0022] In some embodiments, the alkylsilane coupling agent includes at least one of methyltrimethoxysilane and ethyltrimethoxysilane.

[0023] In some of the above embodiments, the role of the alkyl silane coupling agent in the sealant is to quickly form a limiting shell layer, and at the same time cooperate with the polyether modified silane coupling agent and the aromatic silane coupling agent to improve the crosslinking density of the sealant. The above alkyl silane coupling agent has good hydrolysis and condensation activity and has three hydrolysis and condensation sites, which can make the sealant have a relatively suitable crosslinking density and improve the aging resistance and fatigue resistance of the silicone weather-resistant sealant.

[0024] In some embodiments, the filler has a through-pore structure.

[0025] In some of the above embodiments, the use of fillers with a through-porous structure can further improve the aging resistance and fatigue resistance of silicone weatherproof sealants; the reason may be that the fillers with a through-porous structure dispersed in the sealant can promote the diffusion of moisture into the interior of the sealant through capillary induction. In addition to being driven by the moisture gradient, the synergistic capillary induction promotes the migration of the polyether-modified silane coupling agent into the interior of the sealant and cross-linking within the sealant, further increasing the content of the polyether-modified silane coupling agent within the sealant and reducing its content in the outer layer of the sealant, thereby further amplifying the difference between the internal and external cross-linked structures, thereby further improving the aging resistance and fatigue resistance of the ketone weatherproof sealant. As an example, in one embodiment of the present application, SBA-15 with an average particle size of 1 μm and an average pore size of 10 nm is used as a filler.

[0026] In some embodiments, the average particle size of the filler is 0.1-5 μm.

[0027] In some embodiments, the viscosity of the hydroxyl-terminated polydimethylsiloxane is 10,000 to 80,000 mPa·s. Based on the above embodiments, hydroxyl-terminated polydimethylsiloxanes of this viscosity can meet the fluidity requirements of dispersed fillers and additives without causing storage stability or construction control issues due to excessive fluidity. As an example, in one embodiment of the present application, α,ω-dihydroxy polydimethylsiloxane with a viscosity of 20,000 mPa·s is used as the hydroxyl-terminated polydimethylsiloxane.

[0028] In some embodiments, the plasticizer includes dimethyl silicone oil, and the viscosity of the dimethyl silicone oil is 100-500 mPa·s. Based on the above embodiments, the use of dimethyl silicone oil with this viscosity can effectively improve the sealant's workability, flexibility, and elongation at break, and can be used in conjunction with the composite crosslinker to construct a gradient crosslinked structure system that is flexible inside and rigid outside. As an example, in one embodiment of the present application, dimethyl silicone oil with a viscosity of 350 mPa·s is used as the plasticizer.

[0029] It should be noted that the viscosity of the above-mentioned hydroxyl-terminated polydimethylsiloxane and dimethyl silicone oil has a well-known meaning in the art and can be measured using instruments and methods known in the art, for example, by referring to GB / T 10247-2008 "Viscosity Measurement Method"; in this application, unless otherwise specified, the viscosity of a certain material refers to its viscosity at 25°C.

[0030] In some embodiments, the catalyst includes at least one of an organotin catalyst and a titanate catalyst. Based on the above embodiments, the use of these catalysts can promote the hydrolysis and condensation of silane groups, accelerating the curing process of the sealant in a humid environment. For example, dibutyltin dilaurate is used as the catalyst in one embodiment of the present application.

[0031] In some embodiments, functional additives such as antioxidants, mildew inhibitors, pigments, and defoaming agents may be added to the silicone weather-resistant sealant according to actual needs. The amount of the functional additives added is generally 1 to 10 parts.

[0032] In a second aspect, the present application provides a method for preparing a silicone weather-resistant sealant, comprising: providing raw materials of the silicone weather-resistant sealant according to any embodiment of the first aspect; and mixing the raw materials to obtain the silicone weather-resistant sealant.

[0033] According to the present application, the method can produce the silicone weathering sealant of the first aspect, thereby achieving the beneficial effects of the first aspect, namely, excellent aging and fatigue resistance. Furthermore, because the gradient cross-linked structure of the silicone weathering sealant provided by the present application, which is flexible inside and rigid outside, is constructed within the same system by utilizing the reactivity of different cross-linking agents, it does not require multiple components, effectively improving production and construction efficiency.

[0034] In some embodiments, the method includes: uniformly mixing hydroxyl-terminated polydimethylsiloxane, a plasticizer, and a filler, and drying them at a vacuum degree of less than -0.08 MPa and 70~100°C for 1~3 hours, then adding a polyether-modified silane coupling agent, an aromatic silane coupling agent, and an alkyl silane coupling agent, stirring them at a vacuum degree of less than -0.08 MPa and 40~60°C for 0.5~1 hour, then cooling them to below 40°C, adding a catalyst, and stirring them at a vacuum degree of less than -0.08 MPa for 0.5~1 hour to obtain a silicone weatherproof sealant.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] The silicone weather-resistant sealant provided in the present application uses hydroxyl-terminated polydimethylsiloxane as the main material. By designing and using a composite cross-linking agent, and utilizing the molecular structures, hydrolysis rate differences and molecular migration capabilities of three different silane coupling agents, a sealant with a rigid outer layer and a flexible inner layer is formed during the moisture absorption and curing process. The aromatic silane coupling agent is mainly cross-linked in the outer layer to form a rigid outer shell, and the polyether-modified silane coupling agent is mainly cross-linked in the inner layer to form a flexible inner core. Since the aromatic group in the rigid outer shell has good hydrophobicity and ultraviolet absorption ability, and the flexible inner core is conducive to dispersing stress, the silicone weather-resistant sealant has good aging resistance and fatigue resistance. DETAILED DESCRIPTION

[0037] The various embodiments or implementation schemes in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments.

[0038] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with an embodiment or example is included in at least one embodiment or example of the present application. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0039] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0040] In the description of this specification, unless otherwise specified, "parts" refer to "parts by mass".

[0041] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0042] α,ω-dihydroxypolydimethylsiloxane, viscosity 20000 mPa·s;

[0043] Dimethyl silicone oil, viscosity 350 mPa·s;

[0044] SBA-15, average particle size 1 μm, average pore size 10 nm;

[0045] Solid silica, average particle size 1 μm;

[0046] Trimethoxy-terminated polyether modified silane coupling agent, Kaneka SAX530;

[0047] Dimethoxy-terminated polyether modified silane coupling agent, Kaneka SAX015;

[0048] Example 1

[0049] Preparation of silicone weatherproof sealant:

[0050] 100 parts of α,ω-dihydroxypolydimethylsiloxane, 5 parts of dimethyl silicone oil and 50 parts of SBA-15 were added to a planetary stirred tank and mixed for 1 hour, and dried at a vacuum degree of below -0.08 MPa and 90°C for 3 hours. Then, 10 parts of SAX015, 4 parts of trimethoxy(4-fluorophenyl)silane, 12 parts of trimethoxy(4-methoxyphenyl)silane and 6 parts of methyltrimethoxysilane were added, and stirred at a vacuum degree of below -0.08 MPa and 50°C for 1 hour. The mixture was then cooled to 40°C and dibutyltin dilaurate was added. The mixture was stirred at a vacuum degree of below -0.08 MPa for 1 hour to obtain a silicone weathering sealant.

[0051] Example 2

[0052] Preparation of silicone weatherproof sealant:

[0053] The method is substantially the same as Example 1, with the only difference being that Kaneka SAX530 is used instead of Kaneka SAX015.

[0054] Example 3

[0055] Preparation of silicone weatherproof sealant:

[0056] The process is substantially the same as Example 1, except that 16 parts of trimethoxyphenylsilane are used instead of 4 parts of trimethoxy(4-fluorophenyl)silane and 12 parts of trimethoxy(4-methoxyphenyl)silane.

[0057] Example 4

[0058] Preparation of silicone weatherproof sealant:

[0059] The process is substantially the same as Example 1, except that trimethoxy(4-methoxyphenyl)silane is used instead of trimethoxy(4-fluorophenyl)silane (ie, 16 parts of trimethoxy(4-methoxyphenyl)silane are used).

[0060] Example 5

[0061] Preparation of silicone weatherproof sealant:

[0062] The process is substantially the same as Example 1, except that trimethoxy(4-fluorophenyl)silane is used instead of trimethoxy(4-methoxyphenyl)silane (ie, 16 parts of trimethoxy(4-fluorophenyl)silane are used).

[0063] Example 6

[0064] Preparation of silicone weatherproof sealant:

[0065] The method is substantially the same as Example 1, except that 8 parts of trimethoxy(4-fluorophenyl)silane and 8 parts of trimethoxy(4-methoxyphenyl)silane are used instead of 4 parts of trimethoxy(4-fluorophenyl)silane and 12 parts of trimethoxy(4-methoxyphenyl)silane (i.e., the ratio of trimethoxy(4-fluorophenyl)silane to trimethoxy(4-methoxyphenyl)silane is 1:1).

[0066] Example 7

[0067] Preparation of silicone weatherproof sealant:

[0068] The method is substantially the same as Example 1, except that 2.7 parts of trimethoxy(4-fluorophenyl)silane and 13.3 parts of trimethoxy(4-methoxyphenyl)silane are used instead of 4 parts of trimethoxy(4-fluorophenyl)silane and 12 parts of trimethoxy(4-methoxyphenyl)silane (i.e., the ratio of trimethoxy(4-fluorophenyl)silane to trimethoxy(4-methoxyphenyl)silane is approximately 1:5).

[0069] Example 8

[0070] Preparation of silicone weatherproof sealant:

[0071] The process is substantially the same as Example 1, except that solid silica is used instead of SBA-15.

[0072] Comparative Example 1

[0073] Preparation of silicone weatherproof sealant:

[0074] 100 parts of α,ω-dihydroxypolydimethylsiloxane, 5 parts of dimethyl silicone oil and 50 parts of SBA-15 were added to a planetary stirred tank and mixed for 1 hour, and dried at a vacuum degree below -0.08 MPa and 90°C for 3 hours. Then, 10 parts of SAX015 and 22 parts of methyltrimethoxysilane were added, and stirred at a vacuum degree below -0.08 MPa and 50°C for 1 hour. The temperature was then lowered to 40°C, and dibutyltin dilaurate was added. The mixture was stirred at a vacuum degree below -0.08 MPa for 1 hour to obtain a silicone weathering sealant.

[0075] Comparative Example 2

[0076] Preparation of silicone weatherproof sealant:

[0077] 100 parts of α,ω-dihydroxypolydimethylsiloxane, 5 parts of dimethyl silicone oil and 50 parts of SBA-15 were added to a planetary stirred tank and mixed for 1 hour, and dried at a vacuum degree of below -0.08 MPa and 90°C for 3 hours. Then, 4 parts of trimethoxy(4-fluorophenyl)silane, 12 parts of trimethoxy(4-methoxyphenyl)silane and 16 parts of methyltrimethoxysilane were added, and stirred at a vacuum degree of below -0.08 MPa and 50°C for 1 hour. The mixture was then cooled to 40°C and dibutyltin dilaurate was added. The mixture was stirred at a vacuum degree of below -0.08 MPa for 1 hour to obtain a silicone weathering sealant.

[0078] Test section

[0079] The silicone weatherproof sealants obtained in each example and comparative example were tested for their 23°C tensile bond strength, water-ultraviolet light tensile strength retention rate, and fatigue cycle tensile bond strength retention rate with reference to JG / T 475-2015 "Silicone Structural Sealant for Building Curtain Walls". The results are shown in Table 1.

[0080] Table 1

[0081]

[0082] According to Table 1, the silicone weathering sealants obtained in each Example all exhibited high tensile bond strength, water-UV light tensile strength retention, and fatigue cycle tensile bond strength retention. Furthermore, the tensile bond strength and fatigue cycle tensile link strength were significantly higher than those of the comparative examples, indicating that the silicone weathering sealants provided herein not only exhibited good bonding properties but also good aging and fatigue resistance. This may be due to the fact that in Comparative Example 1, no aromatic silane coupling agent was used, resulting in poor aging resistance. Furthermore, the alkyl silane coupling agent used had a relatively rapid hydrolysis activity, which affected the migration and internal curing of the polyether-modified silane coupling agent, resulting in poor bonding strength and fatigue resistance. In Comparative Example 2, no polyether-modified silane coupling agent was used. Due to the absence of silane coupling agent migration, the resulting sealant had a uniform structure. Although the aromatic silane coupling agent effectively improved its aging resistance, it also reduced its bonding and fatigue resistance.

[0083] According to Examples 1 and 2, the use of polyether-modified silane coupling agents with different end groups has a certain impact on the performance of silicone weathering sealant. The use of polyether-modified silane coupling agents with dimethoxy end groups can further improve the aging resistance and fatigue resistance of silicone weathering sealant.

[0084] According to Examples 1, 3 to 7, the use of different aromatic silane coupling agents has a certain impact on the performance of silicone weathering sealant. The use of trimethoxy (4-fluorophenyl) silane and trimethoxy (4-methoxyphenyl) silane can further improve the aging resistance of silicone weathering sealant. When a certain proportion of trimethoxy (4-fluorophenyl) silane and trimethoxy (4-methoxyphenyl) silane is used as an aromatic silane coupling agent, the aging resistance and fatigue resistance of the silicone weathering sealant are better.

[0085] According to Examples 1 and 8, the use of different fillers has a certain influence on the performance of the silicone weather-resistant sealant. When a filler with a through-hole structure is used, the silicone weather-resistant sealant has better aging resistance and fatigue resistance.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A silicone weatherproof sealant, characterized in that: Including the following raw materials by weight: 100 parts of hydroxyl-terminated polydimethylsiloxane, 5-15 parts of polyether-modified silane coupling agent, 10-20 parts of aromatic silane coupling agent, 2-10 parts of alkyl silane coupling agent, 1-10 parts of plasticizer, 40-60 parts of filler, 0.1-2 parts of catalyst; Wherein, the end-capping group of the polyether-modified silane coupling agent is dimethoxysilane; The aromatic silane coupling agent includes trimethoxy (4-fluorophenyl) silane and trimethoxy (4-methoxyphenyl) silane, and the mass ratio of trimethoxy (4-fluorophenyl) silane to trimethoxy (4-methoxyphenyl) silane is 1:2-4; The alkylsilane coupling agent includes at least one of methyltrimethoxysilane and ethyltrimethoxysilane; The filler has a through-pore structure.

2. The silicone weatherproof sealant according to claim 1, characterized in that: The viscosity of the hydroxyl-terminated polydimethylsiloxane is 10,000-80,000 mPa·s.

3. The silicone weatherproof sealant according to claim 1, characterized in that: The plasticizer includes dimethyl silicone oil, and the viscosity of the dimethyl silicone oil is 100-500 mPa·s.

4. The silicone weatherproof sealant according to claim 1, characterized in that: The catalyst includes at least one of an organic tin catalyst and a titanate catalyst.

5. A method for preparing a silicone weather-resistant sealant, characterized in that: include: Providing raw materials for the silicone weather-resistant sealant according to any one of claims 1 to 4; The raw materials are mixed to obtain a silicone weather-resistant sealant.

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