Two-component organic silicon sealant as well as preparation method and application thereof

Abstract

The invention relates to the technical field of high polymer materials, and discloses a two-component organic silicon sealant as well as a preparation method and application thereof. The bi-component organic silicon sealant is prepared from the following components in parts by mass: a component A: 80 to 120 parts of alpha, omega dihydroxy polydimethylsiloxane, 5 to 20 parts of self-repairing microcapsules, 5 to 20 parts of plasticizer, 5 to 50 parts of reinforcing filler and 0.01 to 0.5 part of catalyst; the component B comprises the following components in parts by weight: 80-120 parts of alkoxy-terminated polydimethylsiloxane, 0-20 parts of self-repairing microcapsules, 5-20 parts of a plasticizer, 5-50 parts of reinforcing filler, 2-20 parts of a cross-linking agent and 1-10 parts of a coupling agent; wherein a core material of the self-repairing microcapsule comprises a mixture of hydroxyl-terminated polysiloxane and an organic tin catalyst. The self-repairing effect of the double-component organic silicon sealant depends on the synergistic effect of the repairing component and the microcapsule controlled release structure, the industrial problems that a traditional sealant is irreversible in damage and high in maintenance cost are solved, and the long-term service reliability and the service life of the sealant in a severe environment are remarkably improved.

Description

Technical Field

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

[0002] Two-component condensation-type silicone sealants have been widely used in high-end fields such as building curtain walls, door and window sealing, electronic and electrical encapsulation, automotive manufacturing, and aerospace due to their excellent high and low temperature resistance, weather resistance, electrical insulation, and ease of application. However, with increasingly complex application environments and ever-increasing requirements for material reliability, traditional two-component silicone sealants have revealed a series of key technical bottlenecks during long-term use: First, existing sealants are prone to developing microcracks (typically ≤0.3mm wide) inside or at interfaces during service due to mechanical vibration, thermal cycling stress, UV aging, or chemical corrosion. Once these microcracks form, they cannot close or repair themselves; instead, they expand over time, leading to a gradual decline in sealing performance and even complete failure. Because these cracks are difficult to detect with the naked eye and are randomly distributed, they often require complete disassembly or replacement of the sealing components, resulting in high maintenance costs and potentially affecting the continuity and safety of the overall structure.

[0003] Secondly, current methods for repairing sealant damage are extremely limited and inefficient. Common methods, such as external injection of repair adhesive or local filling, are not only cumbersome and require highly skilled technicians, but also struggle to accurately locate and repair hidden or minute damage areas. The repaired interface often suffers from weak adhesion and poor durability, failing to restore the original sealing and mechanical properties.

[0004] Secondly, traditional sealants have limited functionality and lack proactive response and self-healing capabilities to damage. Although some studies have attempted to introduce self-healing components into colloids, most focus on intrinsic self-healing systems (such as designs based on dynamic bonds). These systems have complex synthesis processes, high costs, and often negatively impact the original mechanical properties, aging resistance, and process applicability of the matrix material, making them difficult to promote and apply in industrial production. Furthermore, some exogenous self-healing systems use repair agents with poor compatibility with the sealant itself, resulting in low repair efficiency, or the repair agents cannot maintain long-term stability under complex environments after release. This means that the self-healing function can only be achieved once or a limited number of times, failing to meet the needs of multiple damage repairs in practical engineering.

[0005] Therefore, how to endow two-component silicone sealants with efficient, reliable and durable self-healing capabilities while maintaining their excellent overall performance has become a key technical problem that urgently needs to be solved in this field. 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, one objective of the present invention is to provide a two-component silicone sealant.

[0007] The second objective of this invention is to provide a method for preparing this two-component silicone sealant.

[0008] The third objective of this invention is to provide applications for this two-component silicone sealant.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A first aspect of the present invention provides a two-component silicone sealant comprising the following components in parts by weight: Component A: α, ω 80-120 parts of dihydroxy polydimethylsiloxane, 5-20 parts of self-healing microcapsules, 5-20 parts of plasticizer, 5-50 parts of reinforcing filler, and 0.01-0.5 parts of catalyst; Component B: 80-120 parts of alkoxy-terminated polydimethylsiloxane, 0-20 parts of self-healing microcapsules, 5-20 parts of plasticizer, 5-50 parts of reinforcing filler, 2-20 parts of crosslinking agent, and 1-10 parts of coupling agent; The core material of the self-healing microcapsule comprises a mixture of hydroxyl-terminated polysiloxane and organotin catalyst.

[0010] In some embodiments of the present invention, the two-component silicone sealant comprises the following components in parts by weight: Component A: α, ω 90-110 parts of dihydroxy polydimethylsiloxane, 5-15 parts of self-healing microcapsules, 5-15 parts of plasticizer, 10-30 parts of reinforcing filler, and 0.01-0.1 parts of catalyst; Component B: 90-110 parts of alkoxy-terminated polydimethylsiloxane, 0-15 parts of self-healing microcapsules, 5-15 parts of plasticizer, 10-30 parts of reinforcing filler, 2-10 parts of crosslinking agent, and 1-5 parts of coupling agent.

[0011] In some preferred embodiments of the present invention, the two-component silicone sealant comprises the following components in parts by weight: Component A: α, ω 95-105 parts of dihydroxy polydimethylsiloxane, 5-10 parts of self-healing microcapsules, 5-10 parts of plasticizer, 10-20 parts of reinforcing filler, and 0.01-0.08 parts of catalyst; Component B: 95-105 parts of alkoxy-terminated polydimethylsiloxane, 0-10 parts of self-healing microcapsules, 5-10 parts of plasticizer, 10-20 parts of reinforcing filler, 2-8 parts of crosslinking agent, and 1-3 parts of coupling agent.

[0012] In some embodiments of the present invention, the mass ratio of component A to component B is 1:(0.8-1.2).

[0013] In some preferred embodiments of the present invention, the mass ratio of component A to component B is 1:(0.9-1.1).

[0014] In some embodiments of the present invention, the α, ω The viscosity of dihydroxy polydimethylsiloxane at 25°C is 1500-50000 mPa·s.

[0015] In some embodiments of the present invention, the alkoxy-terminated polydimethylsiloxane is selected from at least one of α,ω-dimethoxy-terminated polydimethylsiloxane, α,ω-trimethoxy-terminated polydimethylsiloxane, α,ω-diethoxy-terminated polydimethylsiloxane, α,ω-triethoxy-terminated polydimethylsiloxane, α,ω-trimethoxysilylethyl-terminated polydimethylsiloxane, and α,ω-triethoxysilylethyl-terminated polydimethylsiloxane.

[0016] In some embodiments of the present invention, in the core material of the self-healing microcapsule, the molecular weight of the hydroxyl-terminated polysiloxane is 3000-5000 Da, and the mass ratio of the hydroxyl-terminated polysiloxane to the organotin catalyst is (8-12):1.

[0017] In some preferred embodiments of the present invention, the mass ratio of the hydroxyl-terminated polysiloxane to the organotin catalyst is (9-11):1.

[0018] In some embodiments of the present invention, the hydroxyl-terminated polysiloxane is selected from at least one of hydroxyl-terminated polydimethylsiloxane, hydroxyl-terminated polymethylphenylsiloxane, and hydroxyl-terminated polymethylvinylsiloxane.

[0019] In some preferred embodiments of the present invention, the hydroxyl-terminated polysiloxane is a hydroxyl-terminated polydimethylsiloxane.

[0020] In some embodiments of the present invention, the organotin catalyst is selected from at least one of dibutyltin dilaurate, dioctyltin dilaurate, stannous octoate, dibutyltin diacetate, dimethyltin dioctyldecanoate, and dibutyltin diacetate.

[0021] In some preferred embodiments of the present invention, the organotin catalyst is dibutyltin dilaurate.

[0022] In some embodiments of the present invention, the shell material of the self-healing microcapsule comprises urea-formaldehyde resin.

[0023] In some embodiments of the present invention, the particle size of the self-healing microcapsules is less than 100 μm.

[0024] In some preferred embodiments of the present invention, the particle size of the self-healing microcapsules is 1-10 μm.

[0025] In some embodiments of the present invention, the self-healing microcapsules are prepared by a method comprising the following steps: Hydroxyl-terminated polysiloxane was mixed with an organotin catalyst to form a repair solution, which was then dispersed in an aqueous solution containing urea-formaldehyde resin prepolymer. The pH was adjusted to 3.5-4.0, and the mixture was reacted at 40-60℃ for 1-3 hours to obtain the self-healing microcapsules.

[0026] In some embodiments of the present invention, the preparation of the self-healing microcapsules, wherein adjusting the pH to 3.5-4.0 includes adding a pH adjuster; the pH adjuster includes glacial acetic acid.

[0027] In some embodiments of the present invention, the self-healing microcapsules are prepared at a reaction temperature of 45-55°C for 1-2 hours.

[0028] In some embodiments of the present invention, the self-healing microcapsules are prepared in an aqueous solution containing urea-formaldehyde resin prepolymer, wherein the content of urea-formaldehyde resin prepolymer in the solution is 30wt%-50wt%; and the volume ratio of the repair solution to the aqueous solution containing urea-formaldehyde resin prepolymer is 1:(2-4).

[0029] In some embodiments of the present invention, the self-healing microcapsules are prepared by the aqueous solution containing urea-formaldehyde resin prepolymer, which is obtained by mixing and reacting urea and formaldehyde aqueous solution; the concentration of the formaldehyde aqueous solution is 35w%-37wt%; and the molar ratio of urea to formaldehyde is 1:(1.5-2.5).

[0030] In some embodiments of the present invention, the preparation of self-healing microcapsules, after the reaction is completed, further includes the operation of centrifuging to collect the solid phase and drying it.

[0031] In some embodiments of the present invention, in components A and B, the plasticizer is independently selected from at least one of dimethyl silicone oil, methylphenyl silicone oil, hydroxyl silicone oil, and white oil; the viscosity of the plasticizer at 25°C is 50-2000 mPa·s.

[0032] In some embodiments of the present invention, the reinforcing fillers in components A and B are each independently selected from at least one of gaseous silica, precipitated silica, carbon black, nano-calcium carbonate, heavy calcium carbonate, silica powder, and talc.

[0033] In some embodiments of the present invention, the crosslinking agent is selected from organosilicon compounds containing at least two hydrolyzable alkoxy groups or oligomers thereof.

[0034] In some preferred embodiments of the present invention, the crosslinking agent is selected from tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, ethyl silicate hydrolysate oligomers, 1,2 bis(trimethoxysilyl)ethane, 1,2 bis(triethoxysilyl)ethane, 1,2 bis(methyldimethoxysilyl)ethane, 1,2 At least one of bis(methyldiethoxysilyl)ethane, polymethyltriethoxysilane, and polymethyltripropoxysilane.

[0035] In some embodiments of the present invention, the coupling agent is selected from alkoxysilanes having at least one amino or epoxy group.

[0036] In some preferred embodiments of the present invention, the coupling agent is selected from at least one of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltriethoxysilane.

[0037] In some embodiments of the present invention, the catalyst is selected from organotin catalysts.

[0038] In some preferred embodiments of the present invention, the catalyst is selected from at least one of dibutyltin dilaurate, dioctyltin dilaurate, stannous octoate, dibutyltin diacetate, dimethyltin dioctyldecanoate, and dibutyltin diacetate.

[0039] In some embodiments of the present invention, the catalyst is of the same type as the organotin catalyst contained in the self-healing microcapsule core material.

[0040] A second aspect of the present invention provides a method for preparing the two-component silicone sealant described in the first aspect of the present invention, comprising the following steps: Mix all components of component A except the catalyst, then add the catalyst and continue mixing to obtain component A; Mix all components of component B except for the crosslinking agent and coupling agent, then add the crosslinking agent and coupling agent and continue mixing to obtain component B.

[0041] In some embodiments of the present invention, the preparation of component A, wherein the mixing conditions include: stirring and mixing using a dynamic mixer, and a vacuum degree less than or equal to... 0.09MPa, revolution speed of 20-40r / min, dispersion speed of 300-800r / min, mixing time before adding catalyst of 30-80min, and mixing for 10-20min after adding catalyst.

[0042] In some preferred embodiments of the present invention, the preparation of component A, wherein the mixing conditions include: stirring and mixing using a dynamic mixer, and a vacuum degree less than or equal to 0.09 MPa, revolution speed of 25-35 r / min, dispersion speed of 400-600 r / min, mixing time before adding catalyst of 50-70 min, and mixing for 10-15 min after adding catalyst.

[0043] In some embodiments of the present invention, the preparation of component B, wherein the mixing conditions include: mixing using a stirred tank, with a vacuum degree less than or equal to... 0.09MPa, revolution speed of 20-40r / min, dispersion speed of 300-800r / min, temperature before adding crosslinking agent and coupling agent of 110-130℃, mixing time of 120-240min, cooling to below 35℃, adding crosslinking agent and coupling agent and continuing to mix for 10-30min.

[0044] In some preferred embodiments of the present invention, the preparation of component B, wherein the mixing conditions include: mixing using a stirred tank, with a vacuum degree less than or equal to... 0.09MPa, revolution speed of 25-35r / min, dispersion speed of 400-600r / min, temperature before adding crosslinking agent and coupling agent of 115-125℃, mixing time of 150-200min, cooling to below 35℃, adding crosslinking agent and coupling agent and continuing to mix for 15-20min.

[0045] The third aspect of the present invention provides the application of the two-component silicone sealant described in the first aspect of the present invention in high-end building sealing, electronic packaging, and aerospace fields.

[0046] The basic principles of this invention are explained as follows: The two-component silicone sealant provided by this invention contains ≡Si-OH (α, ω) in component A. Dihydroxypolydimethylsiloxane (DHS-OH) and ≡Si-OR (alkoxy-terminated DHS-OH and crosslinking agent) in component B undergo dehydration condensation under catalyst catalysis to form stable ≡Si-O-Si≡ bonds and release alcohol. The functional component, the crosslinking agent, provides multiple reaction sites, connects polymer chains, forms a three-dimensional network, and determines the hardness, modulus, and strength of the colloid. The alkoxy groups of the coupling agent react with the system, while the amino groups form chemical bonds or strong forces with the substrate surface, greatly improving the adhesive strength. The reinforcing filler significantly improves the tensile strength, tear strength, and abrasion resistance of the colloid through physical interactions. The plasticizer can adjust the viscosity of the system and the modulus and elongation of the cured colloid. Based on the main reaction of ≡Si-OH and ≡Si-OR and the role of each functional component, an organosilicon elastomer containing a large number of Si-O-Si main chains with excellent elasticity, adhesion, and weather resistance was obtained. Moreover, unreacted Si-OH and Si-OR groups still remain inside the cured colloid, especially along the paths where cracks may propagate.

[0047] The self-healing microcapsules have a core-shell structure. The core material consists of low-viscosity hydroxyl-terminated polysiloxane (healing agent) and organotin catalyst. The chemical properties of the healing agent are homologous to the matrix polymer, ensuring perfect compatibility. The wall material is urea-formaldehyde resin, which has moderate hardness and poor compatibility with silicone oil, facilitating encapsulation. The particle size is controlled to be less than 100μm to ensure that it does not affect the construction and colloid uniformity, and can encapsulate sufficient healing agent, and cracks can easily intersect with it. When the colloid is subjected to external force to generate microcracks (≤0.3mm) and propagate inward, a high stress field is formed at the crack tip. The shell of the microcapsules, which are pre-dispersed on the crack propagation path, undergoes brittle fracture under this stress, thereby precisely releasing the internal healing agent and catalyst to the surface of the newly formed crack. This is an autonomous, passive response process that does not require external energy or intervention. The released low-viscosity hydroxyl-terminated polysiloxane repair agent, due to its excellent fluidity and compatibility with the matrix, can quickly wet and spread across the entire crack surface. The repair agent (≡Si-OH), the catalyst released from the ruptured microcapsules, and the active groups originally remaining on the crack surface (≡Si-OH from the matrix and ≡Si-OR from component B) meet, and the exact same condensation reaction is reactivated. Through new Si-O-Si chemical bonds, the two sides of the crack are reconnected, achieving chemical healing of the interface rather than physical filling. The chemical composition of the interface after repair is almost identical to that of the bulk. Since the crack may not exhaust all microcapsules at once, and the repair reaction is selective, the unused microcapsules and residual active sites can cope with subsequent damage, achieving multiple repairs.

[0048] Compared with the prior art, the beneficial effects of the present invention are: The two-component silicone sealant provided by this invention successfully endows traditional sealants with intelligent self-healing capabilities by introducing core-shell structured microcapsules containing hydroxyl-terminated polysiloxane repair agents and catalysts. When microcracks (≤0.3mm) are generated inside the sealant, the stress at the crack tip can cause the microcapsules to rupture, precisely releasing the repair components. At room temperature, the repair agent undergoes a condensation reaction with the active groups remaining at the crack interface, reforming chemical bonds, thereby achieving autonomous and efficient crack repair within 72 hours, with a tensile strength recovery rate of over 85%. This design cleverly reuses the original curing chemical mechanism of the system, ensuring the chemical homogeneity and long-term durability of the repair interface and the substrate, with high performance retention after double 85 aging. At the same time, the introduction of microcapsules does not impair the excellent mechanical properties, application flowability, and mixing process convenience of the sealant itself. The self-healing effect of the two-component silicone sealant relies on the synergistic effect of the repair components and the controlled-release structure of the microcapsules, solving the industry problems of irreversible damage and high maintenance costs of traditional sealants, and significantly improving its reliability and lifespan in harsh environments. Attached Figure Description

[0049] Figure 1 This is a TEM image of the self-healing microcapsules prepared in Example 1. Detailed Implementation

[0050] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments and comparative examples are all available from conventional commercial sources or can be obtained by existing technical methods. Unless otherwise specified, the test or experimental methods are conventional methods in the art.

[0051] Note: Unless otherwise specified, "parts" in the following examples and comparative examples refer to "parts by mass".

[0052] Example 1 This embodiment prepares a two-component silicone sealant, and the steps are as follows: Preparation of self-healing microcapsules: Hydroxyl-terminated polydimethylsiloxane (4000 Da) and dibutyltin dilaurate were mixed at a mass ratio of 10:1 to form a repair solution. Urea was mixed with a 37 wt% formaldehyde aqueous solution to obtain an aqueous solution containing urea-formaldehyde resin prepolymer, wherein the molar ratio of urea to formaldehyde was 1:2 and the content of urea-formaldehyde resin prepolymer in the aqueous solution was 40 wt%. The repair solution was dispersed in the aqueous solution containing urea-formaldehyde resin prepolymer (3:1, v / v), the pH was adjusted to 3.6 with glacial acetic acid, and the reaction was stirred at 50°C for 2 h. After centrifugation and drying, the mixture was passed through a 150-mesh sieve to obtain self-repairing microcapsules-Ⅰ with a particle size of less than 100 μm.

[0053] Preparation of two-component silicone sealant: 100 portions of α, ω Dihydroxypolydimethylsiloxane (10000 mPa·s, 25℃), 10 parts of self-healing microcapsules-I, 15 parts of gas-processed silica, and 8 parts of dimethyl silicone oil (500 mPa·s, 25℃) were added to a dynamic mixer and stirred while maintaining a vacuum level. Below 0.09 MPa, with a revolution speed of 30 r / min and a dispersion speed of 500 r / min, after stirring for 60 min, add 0.05 parts of dibutyltin dilaurate and continue stirring for 15 min to obtain component A; 100 parts of α,ω-trimethoxy-terminated polydimethylsiloxane, 15 parts of gas-bearing silica, and 8 parts of dimethyl silicone oil (500 mPa·s, 25℃) were added to a stirred tank and heated to 120℃ for dehydration and mixing, while maintaining a vacuum level of [missing information]. At a pressure below 0.09 MPa, with a revolution speed of 30 r / min and a dispersion speed of 500 r / min, after stirring for 180 min, the temperature was lowered to below 35℃, and 5 parts of methyltriethoxysilane and 2 parts of γ-aminopropyltrimethoxysilane were added. Stirring was continued for 20 min to obtain component B.

[0054] Figure 1 This is a TEM image of the self-healing microcapsules prepared in Example 1. Figure 1 It can be seen that the self-healing microcapsules are uniform in size and have a distinct core-shell structure, with a particle size of approximately 1-2 μm.

[0055] Example 2 This embodiment prepares a two-component silicone sealant, and the steps are as follows: 100 portions of α, ω Dihydroxypolydimethylsiloxane (10000 mPa·s, 25℃), 8 parts of self-healing microcapsules-I, 15 parts of gas-processed silica, and 8 parts of dimethyl silicone oil (500 mPa·s, 25℃) were added to a dynamic mixer and stirred while maintaining a vacuum level. Below 0.09 MPa, with a revolution speed of 30 r / min and a dispersion speed of 500 r / min, after stirring for 60 min, add 0.05 parts of dibutyltin dilaurate and continue stirring for 15 min to obtain component A; 100 parts of α,ω-trimethoxy-terminated polydimethylsiloxane, 8 parts of self-healing microcapsules-I, 15 parts of gas-generated silica, and 8 parts of dimethyl silicone oil (500 mPa·s, 25℃) were added to a stirred tank and heated to 120℃ for dehydration and mixing, maintaining a vacuum level of [missing information]. At a pressure below 0.09 MPa, with a revolution speed of 30 r / min and a dispersion speed of 500 r / min, after stirring for 180 min, the temperature was lowered to below 35℃, and 5 parts of methyltriethoxysilane and 2 parts of γ-aminopropyltrimethoxysilane were added. Stirring was continued for 20 min to obtain component B.

[0056] Example 3 This embodiment prepares a two-component silicone sealant, and the steps are as follows: Preparation of self-healing microcapsules: Hydroxyl-terminated polydimethylsiloxane (5000 Da) and dibutyltin dilaurate were mixed at a mass ratio of 10:1 to form a repair solution. Urea was mixed with a 37 wt% formaldehyde aqueous solution to obtain an aqueous solution containing urea-formaldehyde resin prepolymer, wherein the molar ratio of urea to formaldehyde was 1:2 and the content of urea-formaldehyde resin prepolymer in the aqueous solution was 40 wt%. The repair solution was dispersed in the aqueous solution containing urea-formaldehyde resin prepolymer (3:1, v / v), the pH was adjusted to 3.6 with glacial acetic acid, and the reaction was stirred at 50°C for 2 h. After centrifugation and drying, the mixture was passed through a 150-mesh sieve to obtain self-healing microcapsules-II with a particle size of less than 100 μm.

[0057] Preparation of two-component silicone sealant: 100 portions of α, ω Dihydroxypolydimethylsiloxane (10000 mPa·s, 25℃), 10 parts of self-healing microcapsules-II, 15 parts of gas-processed silica, and 8 parts of dimethyl silicone oil (500 mPa·s, 25℃) were added to a dynamic mixer and stirred while maintaining a vacuum level. Below 0.09 MPa, with a revolution speed of 30 r / min and a dispersion speed of 500 r / min, after stirring for 60 min, add 0.05 parts of dibutyltin dilaurate and continue stirring for 15 min to obtain component A; 100 parts of α,ω-trimethoxy-terminated polydimethylsiloxane, 15 parts of gas-bearing silica, and 8 parts of dimethyl silicone oil (500 mPa·s, 25℃) were added to a stirred tank and heated to 120℃ for dehydration and mixing, while maintaining a vacuum level of [missing information]. At a pressure below 0.09 MPa, with a revolution speed of 30 r / min and a dispersion speed of 500 r / min, after stirring for 180 min, the temperature was lowered to below 35℃, and 5 parts of methyltriethoxysilane and 2 parts of γ-aminopropyltrimethoxysilane were added. Stirring was continued for 20 min to obtain component B.

[0058] Comparative Example 1 This comparative example prepares a two-component silicone sealant, and the steps are as follows: 100 portions of α, ω Dihydroxypolydimethylsiloxane (10000 mPa·s, 25℃), 15 parts of gas-release silica, and 8 parts of dimethyl silicone oil (500 mPa·s, 25℃) were added to a dynamic mixer and stirred while maintaining a vacuum level. Below 0.09 MPa, with a revolution speed of 30 r / min and a dispersion speed of 500 r / min, after stirring for 60 min, add 0.05 parts of dibutyltin dilaurate and continue stirring for 15 min to obtain component A; 100 parts of α,ω-trimethoxy-terminated polydimethylsiloxane, 15 parts of gas-bearing silica, and 8 parts of dimethyl silicone oil (500 mPa·s, 25℃) were added to a stirred tank and heated to 120℃ for dehydration and mixing, while maintaining a vacuum level of [missing information]. At a pressure below 0.09 MPa, with a revolution speed of 30 r / min and a dispersion speed of 500 r / min, after stirring for 180 min, the temperature was lowered to below 35℃, and 5 parts of methyltriethoxysilane and 2 parts of γ-aminopropyltrimethoxysilane were added. Stirring was continued for 20 min to obtain component B.

[0059] Comparative Example 2 This comparative example prepares a two-component silicone sealant, and the steps are as follows: 100 portions of α, ω Dihydroxy polydimethylsiloxane (10000 mPa·s, 25℃), 9.1 parts hydroxyl-terminated polydimethylsiloxane (4000 Da), 15 parts gas-release silica, and 8 parts dimethyl silicone oil (500 mPa·s, 25℃) were added to a dynamic mixer and stirred while maintaining a vacuum level of [missing information]. Below 0.09 MPa, with a revolution speed of 30 r / min and a dispersion speed of 500 r / min, after stirring for 60 min, add 0.95 parts of dibutyltin dilaurate and continue stirring for 15 min to obtain component A; 100 parts of α,ω-trimethoxy-terminated polydimethylsiloxane, 15 parts of gas-bearing silica, and 8 parts of dimethyl silicone oil (500 mPa·s, 25℃) were added to a stirred tank and heated to 120℃ for dehydration and mixing, while maintaining a vacuum level of [missing information]. At a pressure below 0.09 MPa, with a revolution speed of 30 r / min and a dispersion speed of 500 r / min, after stirring for 180 min, the temperature was lowered to below 35℃, and 5 parts of methyltriethoxysilane and 2 parts of γ-aminopropyltrimethoxysilane were added. Stirring was continued for 20 min to obtain component B.

[0060] Comparative Example 3 This comparative example prepares a two-component silicone sealant, and the steps are as follows: Preparation of urea-formaldehyde resin particles: Urea was mixed with a 37wt% formaldehyde aqueous solution to obtain an aqueous solution containing urea-formaldehyde resin prepolymer, wherein the molar ratio of urea to formaldehyde was 1:2, and the content of urea-formaldehyde resin prepolymer in the aqueous solution was 40wt%. The pH was adjusted to 3.6 with glacial acetic acid, and the reaction was stirred at 50℃ for 2 hours. After centrifugation and drying, the product was passed through a 150-mesh sieve to obtain urea-formaldehyde resin particles with a particle size of less than 100μm.

[0061] Preparation of two-component silicone sealant: 100 portions of α, ω Dihydroxypolydimethylsiloxane (10000 mPa·s, 25℃), 10 parts urea-formaldehyde resin granules, 15 parts gas-fired silica, and 8 parts dimethyl silicone oil (500 mPa·s, 25℃) were added to a dynamic mixer and stirred while maintaining a vacuum level. Below 0.09 MPa, with a revolution speed of 30 r / min and a dispersion speed of 500 r / min, after stirring for 60 min, add 0.05 parts of dibutyltin dilaurate and continue stirring for 15 min to obtain component A; 100 parts of α,ω-trimethoxy-terminated polydimethylsiloxane, 15 parts of gas-bearing silica, and 8 parts of dimethyl silicone oil (500 mPa·s, 25℃) were added to a stirred tank and heated to 120℃ for dehydration and mixing, while maintaining a vacuum level of [missing information]. At a pressure below 0.09 MPa, with a revolution speed of 30 r / min and a dispersion speed of 500 r / min, after stirring for 180 min, the temperature was lowered to below 35℃, and 5 parts of methyltriethoxysilane and 2 parts of γ-aminopropyltrimethoxysilane were added. Stirring was continued for 20 min to obtain component B.

[0062] Performance testing The components A and B prepared in Examples 1-3 and Comparative Examples 1-3 were mixed at a mass ratio of 1:1 to obtain a two-component silicone sealant. The following performance tests were performed on the two-component silicone sealants in Examples 1-3 and Comparative Examples 1-3: 1. Tensile strength: Tested in accordance with GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber"; 2. Elongation at break: Tested in accordance with GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber"; 3. Shore hardness: The test shall be conducted in accordance with GB / T 531.1-2008 "Test method for indentation hardness of vulcanized rubber or thermoplastic rubber - Part 1: Shore hardness tester method (Shore hardness)"; 4. Self-healing performance test: A 0.2mm deep crack was made with a blade. After 72 hours, the surface crack condition of the sample was observed, and the tensile strength and elongation at break of the sample were tested. The tensile strength repair rate and elongation at break repair rate were calculated. Tensile strength repair rate = (Tensile strength after fracture repair / Initial tensile strength) × 100% Elongation at break repair rate = Elongation at break after fracture repair / Initial elongation at break × 100%; 5. Double 85 Aging Test: The repaired sample was placed in an aging oven at 85℃ and 85%RH for 1000 hours. The tensile strength of the sample after aging was tested, and the tensile strength retention rate was calculated. Tensile strength retention rate = tensile strength after aging / tensile strength after fracture repair × 100%.

[0063] Table 1 Performance test results of the two-component silicone sealants in Examples 1-3 and Comparative Examples 1-3

[0064] Table 1 shows the performance test results of the two-component silicone sealants in Examples 1-3 and Comparative Examples 1-3. As shown in Table 1, the two-component silicone sealant prepared in Example 1 has an initial tensile strength of 2.22 MPa and an elongation at break of 410%, exhibiting excellent mechanical properties. In the self-healing test, the tensile strength repair rate reached 89.2%, and the elongation at break repair rate reached 95.1%, with no obvious cracks on the surface, indicating that the two-component silicone sealant has good self-healing performance. After 1000 hours of double 85 aging test, the repaired sample still retained 85.9% of its tensile strength, indicating that the repair interface has excellent chemical stability. The Si-O-Si bonds formed during the repair are as resistant to hydrolysis and thermal-oxidative aging as the matrix, and the self-healing is not a one-time repair, allowing the repaired area to serve for a long time. Compared with Example 1, Example 2 showed a slight decrease in the tensile strength repair rate and the elongation at break repair rate, but still maintained a relatively good level. In Example 3, self-healing microcapsules were prepared using hydroxyl-terminated polydimethylsiloxane with a higher molecular weight. The tensile strength recovery rate after repair was the highest (91.0%), but the elongation at break recovery rate was the lowest (80.9%). This indicates that the molecular chains of the high molecular weight repair agent are longer, and the molecular chains at the repair interface are more tightly entangled, resulting in higher load-bearing capacity (strength). However, the high molecular weight repair agent has extremely high viscosity and poor fluidity, resulting in poor spreading and wetting effects within the crack. This leads to uneven distribution of the repair material within the crack, creating weak points. Under tension, these uneven points are prone to breakage again, resulting in a lower overall elongation recovery. Therefore, it is necessary to control the molecular weight of the hydroxyl-terminated polydimethylsiloxane to achieve a balance between repair strength and repair integrity. In Comparative Example 1, without the addition of self-healing microcapsules, the two-component silicone sealant showed almost no repair capability, with a tensile strength repair rate of 41.7% and an elongation at break recovery rate of 39.9%. The small amount of "repair" at the cracks likely stemmed from the elastic recoil or surface tension of the sealant itself, rather than active chemical repair. This indicates that without self-healing microcapsules, the system is simply an ordinary sealant with excellent mechanical properties but no self-healing ability. Comparative Example 2, with the direct addition of repair components without encapsulation, showed a tensile strength repair rate of 43.2% and an elongation at break recovery rate of 38.7%, also exhibiting extremely poor repair capability. This demonstrates that simply having repairing chemical components is insufficient. During mixing and curing, these repair agents and catalysts are prematurely consumed, diffused and deactivated, or unevenly distributed, failing to accumulate and effectively react at the cracks when damage occurs. This underscores the indispensable role of microcapsules in spatiotemporal isolation and controlled release. In the comparative example, the addition of shell material resulted in a tensile strength recovery rate of 41.4% and an elongation at break recovery rate of 36.3%, indicating extremely poor repair ability. This suggests that the wall material of the microcapsule itself does not produce a repair effect, ruling out the hypothesis that the performance improvement is due to the pinning effect or physical filling.

Claims

1. A two-component silicone sealant, characterized in that, The components include the following parts by weight: Component A: α, ω 80-120 parts of dihydroxy polydimethylsiloxane, 5-20 parts of self-healing microcapsules, 5-20 parts of plasticizer, 5-50 parts of reinforcing filler, and 0.01-0.5 parts of catalyst; Component B: 80-120 parts of alkoxy-terminated polydimethylsiloxane, 0-20 parts of self-healing microcapsules, 5-20 parts of plasticizer, 5-50 parts of reinforcing filler, 2-20 parts of crosslinking agent, and 1-10 parts of coupling agent; The core material of the self-healing microcapsule comprises a mixture of hydroxyl-terminated polysiloxane and organotin catalyst.

2. The two-component silicone sealant according to claim 1, characterized in that, The mass ratio of component A to component B is 1:(0.8-1.2).

3. The two-component silicone sealant according to claim 1, characterized in that, The alkoxy-terminated polydimethylsiloxane is selected from at least one of α,ω-dimethoxy-terminated polydimethylsiloxane, α,ω-trimethoxy-terminated polydimethylsiloxane, α,ω-diethoxy-terminated polydimethylsiloxane, α,ω-triethoxy-terminated polydimethylsiloxane, α,ω-trimethoxysilylethyl-terminated polydimethylsiloxane, and α,ω-triethoxysilylethyl-terminated polydimethylsiloxane.

4. The two-component silicone sealant according to claim 1, characterized in that, In the core material of the self-healing microcapsule, the molecular weight of the hydroxyl-terminated polysiloxane is 3000-5000 Da, and the mass ratio of the hydroxyl-terminated polysiloxane to the organotin catalyst is (8-12):

1. And / or, the shell material of the self-healing microcapsules includes urea-formaldehyde resin; And / or, the particle size of the self-healing microcapsules is less than 100 μm.

5. The two-component silicone sealant according to claim 4, characterized in that, The self-healing microcapsules are prepared by a method comprising the following steps: Hydroxyl-terminated polysiloxane was mixed with an organotin catalyst to form a repair solution, which was then dispersed in an aqueous solution containing urea-formaldehyde resin prepolymer. The pH was adjusted to 3.5-4.0, and the mixture was reacted at 40-60℃ for 1-3 hours to obtain the self-healing microcapsules.

6. The two-component silicone sealant according to claim 5, characterized in that, The self-healing microcapsules are prepared in such a way that the content of urea-formaldehyde resin prepolymer in the aqueous solution is 30wt%-50wt%; the volume ratio of the repair solution to the aqueous solution containing urea-formaldehyde resin prepolymer is 1:(2-4).

7. The two-component silicone sealant according to claim 1, characterized in that, In components A and B, the plasticizer is independently selected from at least one of dimethyl silicone oil, methylphenyl silicone oil, hydroxyl silicone oil, and white oil; the viscosity of the plasticizer at 25°C is 50-2000 mPa·s. And / or, the reinforcing fillers are each independently selected from at least one of the following: gaseous silica, precipitated silica, carbon black, nano calcium carbonate, heavy calcium carbonate, silica powder, and talc.

8. The two-component silicone sealant according to claim 1, characterized in that, The crosslinking agent is selected from organosilicon compounds containing at least two hydrolyzable alkoxy groups or their oligomers; And / or, the coupling agent is selected from alkoxysilanes having at least one amino or epoxy group; And / or, the catalyst is selected from organotin catalysts.

9. A method for preparing the two-component silicone sealant according to any one of claims 1-8, characterized in that, Includes the following steps: Mix all components of component A except the catalyst, then add the catalyst and continue mixing to obtain component A; Mix all components of component B except for the crosslinking agent and coupling agent, then add the crosslinking agent and coupling agent and continue mixing to obtain component B.

10. The application of the two-component silicone sealant according to any one of claims 1-8 in high-end building sealing, electronic packaging, and aerospace fields.

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