A quick-curing environment-friendly two-component silicone adhesive and a preparation method thereof

Abstract

The application relates to a fast-cured environment-friendly two-component organic silicon adhesive and a preparation method thereof, raw materials for preparing the two-component organic silicon adhesive include an A component and a B component, the A component includes the following components in parts by weight: 30-60 parts of hydroxyl-terminated polydimethylsiloxane, 30-60 parts of inorganic fillers, 1-10 parts of ethylene-propylene-diene rubber-polydimethylsiloxane graft polymer, 1-5 parts of amino silicon oil, 1-5 parts of fumed silica, and 0.2-1 part of an organic alkali catalyst; the B component includes the following components in parts by weight: 30-60 parts of alkoxy-terminated polydimethylsiloxane, 20-50 parts of inorganic fillers, 1-10 parts of color paste, 1-5 parts of adhesion promoter, 5-15 parts of crosslinking agent, and 0.2-1 part of a titanate catalyst. The two-component organic silicon adhesive has unexpected curing effect and curing speed through the synergy between the hydroxyl-terminated polydimethylsiloxane and the alkoxy-terminated polydimethylsiloxane and the introduction of the ethylene-propylene-diene rubber-polydimethylsiloxane graft polymer.

Description

Technical Field

[0001] This application relates to the field of adhesive technology, and in particular to a fast-curing, environmentally friendly two-component silicone adhesive and its preparation method. Background Technology

[0002] In the field of silicone adhesive technology, the development of two-component silicone adhesives has brought innovation to numerous industries. In the transportation sector, they are used for sealing automotive engines and aerospace equipment, ensuring the safe and stable operation of vehicles and reducing the risk of malfunctions caused by sealing problems. In the energy industry, two-component silicone adhesives provide sealing protection for pipelines and electrical equipment, improving the efficiency of energy transmission and utilization. In the medical field, they can be used for sealing medical devices, ensuring the hygiene and reliability of these devices. With the continuous development of various industries, the performance requirements for two-component silicone adhesives are becoming increasingly stringent, demanding that they function effectively in more complex environments and higher-standard scenarios.

[0003] In the past, the industry has employed several common technical methods to address issues related to two-component silicone adhesives. These typically use hydroxyl-terminated polydimethylsiloxanes as a base, relying on a condensation reaction initiated by moisture to achieve curing. To accelerate the reaction, some systems utilize organotin catalysts.

[0004] However, these traditional techniques have significant drawbacks. The curing method of hydroxyl-terminated polydimethylsiloxanes is heavily dependent on moisture, resulting in slow curing speeds. Furthermore, moisture-induced pre-reactions during low-temperature mixing can destabilize the colloidal properties, affecting curing uniformity and mechanical properties. Organotin catalysts are harmful to health, limiting the application of adhesives in high-standard fields, such as food contact materials, where adhesives containing organotin catalysts cannot be used. Therefore, developing an environmentally friendly two-component silicone adhesive with good mechanical properties, rapid curing, and no organotin catalysts is of significant practical importance. Summary of the Invention

[0005] To improve the mechanical properties and curing speed of silicone adhesives, this application provides a fast-curing, environmentally friendly two-component silicone adhesive and its preparation method.

[0006] In a first aspect, this application provides a fast-curing, environmentally friendly two-component silicone adhesive, employing the following technical solution:

[0007] A fast-curing, environmentally friendly two-component silicone adhesive comprises component A and component B. Component A comprises the following components in parts by weight: 30-60 parts of hydroxyl-terminated polydimethylsiloxane, 30-60 parts of inorganic filler, 1-10 parts of polyolefin elastomer-silicone graft polymer, 1-5 parts of amino silicone oil, 1-5 parts of fumed silica, and 0.2-1 parts of organic base catalyst. Component B comprises the following components in parts by weight: 30-60 parts of alkoxy-terminated polydimethylsiloxane, 20-50 parts of inorganic filler, 1-10 parts of colorant, 1-5 parts of adhesion promoter, 5-15 parts of crosslinking agent, and 0.2-1 parts of titanate catalyst. The polyolefin elastomer-silicone graft polymer is an ethylene propylene diene monomer (EPDM) rubber-polydimethylsiloxane graft polymer.

[0008] The inventors discovered that by synergistically combining hydroxyl-terminated and alkoxyl-terminated polydimethylsiloxanes, and introducing a EPDM-polydimethylsiloxane graft polymer as a toughening enhancer, two-component silicone adhesives can possess excellent properties such as rapid curing, high toughness, and environmental friendliness. Specifically, hydroxyl-terminated polydimethylsiloxanes, after activation by an organic base catalyst, form highly nucleophilic silanolates, providing ample reaction sites for the crosslinking reaction. Meanwhile, alkoxyl-terminated polydimethylsiloxanes, after activation by a titanate catalyst, exhibit enhanced electrophilicity, making them more susceptible to nucleophilic attack. When components A and B are mixed, the energy barrier of the condensation reaction is significantly lowered, not only increasing the crosslinking density of the reaction between components A and B but also effectively improving the curing speed of the two-component silicone adhesive. Furthermore, the alkoxy groups at the ends of the polydimethylsiloxane molecular chains with alkoxy groups are highly reactive groups. Once they are mixed with component A and come into contact with trace amounts of water diffused in the environment or system, they can undergo hydrolysis and condensation directly without prior activation, which further improves the curing speed of the two-component silicone adhesive.

[0009] The synergistic combination of hydroxyl-terminated polydimethylsiloxane and alkoxy-terminated polydimethylsiloxane not only solves the problem of slow colloid curing speed of pure hydroxyl system, but also makes up for the defect of insufficient crosslinking density of pure alkoxy system. This makes the whole curing process fast at the beginning and solid at the end, and the overall curing efficiency is far greater than that of single polymer system.

[0010] In two-component silicone adhesives, the polydimethylsiloxane segments in the EPDM-polydimethylsiloxane graft polymer are thermodynamically compatible with hydroxyl-terminated and alkoxy-terminated polydimethylsiloxanes, achieving excellent dispersion. This allows the EPDM segments to be stably dispersed in the cross-linked network during rapid curing, increasing the impact resistance points of the colloid and improving its overall mechanical properties. When the rapidly cured colloid is subjected to external impact or tension, the EPDM segments can efficiently induce and terminate a large number of microcracks, preventing them from developing into destructive macrocracks and improving its impact resistance. At the same time, the colloid acts as a stress concentration point, inducing the orientation and slippage of the surrounding matrix polymer chains, absorbing a large amount of energy, and effectively improving the tensile strength of the colloid.

[0011] This application achieves unexpected improvements in mechanical properties and curing speed in two-component silicone adhesives through the synergistic effect of hydroxyl-terminated polydimethylsiloxane, alkoxy-terminated polydimethylsiloxane, and EPDM-polydimethylsiloxane graft polymer.

[0012] In one specific feasible implementation, the inorganic filler in component A is fused silica powder with a silane coupling agent surface modified.

[0013] Fused silica powder itself provides a skeletal support with high hardness and low coefficient of thermal expansion. After treatment with a silane coupling agent (such as vinyltrimethoxysilane), the interfacial compatibility is greatly improved, and filler agglomeration is prevented. This allows the filled system to achieve high modulus and high hardness while significantly reducing internal stress and greatly improving durability, with effects far superior to simple physical mixing.

[0014] Through the synergistic effect of surface modification with fused silica powder and silane coupling agent, the cured two-component silicone adhesive possesses excellent properties such as high mechanical strength, low shrinkage, and superior stability.

[0015] In one specific feasible implementation, the amino silicone oil in component A above has an ammonia value of 0.2-0.6 mmol / g.

[0016] The inventors discovered that adding amino silicone oil with an ammonia value of 0.2-0.6 mmol / g can give two-component silicone adhesives excellent adhesion, wet durability, and accelerated curing performance. Specifically, the amino group at one end of the amino silicone oil molecular chain is a strongly polar group that can generate a strong affinity for inorganic substrates such as glass, metal, and ceramics, and even form chemical bonds, especially in terms of wet bonding strength and durability. Meanwhile, the siloxane backbone at the other end of the amino silicone oil molecular chain is compatible with the silicone adhesive matrix, enabling the two-component silicone adhesive to have excellent adhesion. Furthermore, amino silicone oil itself is a flexible linear polymer; introducing it into the cross-linked network of the colloid not only increases the flexibility of the colloid network but also moderately increases the elongation at break of the cured colloid, thereby improving the toughness, impact resistance, and vibration resistance of the colloid.

[0017] Amino silicone oil itself contains basic amino groups, which can form a basic synergistic effect with organic base catalysts. The amino group can form strong hydrogen bonds with the hydrogen atoms in the silanol group, further increasing the electron cloud density of the silanol group and enhancing its nucleophilicity, thereby generating a highly nucleophilic silanolate.

[0018] In one specific feasible implementation, the organic base catalyst in component A above is 1,8-diazabicyclo(5.4.0)undec-7-ene.

[0019] The inventors discovered that 1,8-diazabicyclo(5.4.0)undec-7-ene, as a strong organic base, can efficiently activate the silanol groups at the ends of the hydroxyl-terminated polydimethylsiloxane in component A, greatly enhancing its nucleophilicity. Simultaneously, the titanate in component B activates the silicon atoms in the crosslinking agent, enhancing its electrophilicity. The synergistic activation of these two components constitutes an "acid-base synergistic catalysis" system, achieving dual activation of both nucleophiles and electrophiles. This drastically lowers the energy barrier of the condensation reaction, resulting in a curing rate far exceeding that of traditional single acid or base catalysts. Deep curing is achieved in a very short time at room temperature, and the system is environmentally friendly and non-toxic.

[0020] In one specific implementation, component A further includes sodium-based bentonite that has been surface-modified with aminosilane.

[0021] By combining sodium-based bentonite modified with aminosilane surface and the moisture in the curing environment, a two-component organosilicon achieves excellent anti-sagging and accelerated deep curing properties. Specifically, the modified bentonite is stable during storage. After application, it preferentially absorbs ambient moisture and expands. This process locally releases water molecules, providing moisture for internal condensation reactions and accelerating deep curing. Furthermore, the sheet-like expansion physically crosslinks the polymer chains, generating post-curing thixotropy. This fundamentally solves the two major technological challenges of traditional colloids: surface dryness without internal dryness and sagging during vertical surface application, achieving a perfect balance between curing speed and workability.

[0022] In one specific implementation, the adhesion promoter in component B includes acrylate-containing aminosilane dimers and hydroxyl-containing aminosilane dimers.

[0023] Through the synergistic combination of acrylate-containing aminosilane dimers and hydroxyl-containing aminosilane dimers, two-component silicone adhesives achieve universal, robust, and ultra-durable bonding interfaces for inorganic and organic heterogeneous substrates.

[0024] Specifically, aminosilane dimers containing acrylate groups have good compatibility with substrates (such as plastics and rubber) and can improve interfacial wettability; aminosilane dimers containing hydroxyl groups contain hydroxyl and amino groups after epoxy ring opening, and have strong chemical bonding ability with polar substrates such as metals and glass. The combination of the two can broaden the range of adhesive acceptors and at the same time strengthen interfacial adhesion.

[0025] The residual active sites of the amino and acrylate groups in the aminosilane dimer containing acrylate groups can form a synergistic catalysis with the organic base catalyst of component A and the titanate catalyst of component B, promoting the cross-linking reaction of siloxanes; the hydroxyl groups of the aminosilane dimer containing hydroxyl groups can undergo a condensation reaction with cross-linking agents (such as alkoxysilanes), shortening the curing time, and together with the aminosilane dimer containing acrylate groups, achieve the requirement of "rapid curing".

[0026] The acrylate segments of aminosilane dimers containing acrylate groups can enhance compatibility with polyolefin elastomers-organosilicon graft polymers and reduce system stratification; the amino groups of aminosilane dimers containing hydroxyl groups interact with the hydroxyl groups on the surface of inorganic fillers (such as fused silica powder) to improve filler dispersibility. The combination of the two can balance system uniformity and storage stability.

[0027] In one specific implementation, the mass ratio of the acrylate-containing aminosilane dimer to the hydroxyl-containing aminosilane dimer is 1:(0.8-1.2).

[0028] By combining acrylate-containing aminosilane dimers and hydroxyl-containing aminosilane dimers in the above proportions, a high-performance interface layer is constructed for the colloid that meets both polar and non-polar bonding requirements while ensuring a stable curing rate.

[0029] When an excessive amount of acrylate-containing aminosilane dimer is added, the adhesion strength of the system to polar substrates (metals, glass) decreases, and the interface is easily peeled off after curing.

[0030] When an excessive amount of hydroxyl-containing aminosilane dimer is added, the excess of amine groups may cause the siloxane to crosslink too quickly, resulting in "explosive polymerization" or uneven curing. At the same time, the compatibility with non-polar substrates (plastics, rubber) deteriorates, and the product lacks toughness.

[0031] In one specific implementation scheme, the crosslinking agent in component B is selected from one or more of methyltrimethoxysilane, tetramethoxysilane, vinyltrimethoxysilane, tetraethoxysilane, vinyltriethoxysilane, and ethyl silicate.

[0032] By adding the crosslinking agents listed above to the adhesive system, the crosslinking agents contain multiple hydrolyzable alkoxy groups, which can undergo condensation reactions with the active groups (such as Si-OH and alkoxy groups) in components A and B to form a three-dimensional crosslinking network, ensuring the curing strength and structural stability of the colloid. Multiple crosslinking agents can be flexibly combined, and the crosslinking density can be adjusted according to the needs to adapt to the requirements of different scenarios for the hardness and flexibility of the colloid. All of them are environmentally friendly reagents and meet the non-toxic environmental protection standards.

[0033] In one specific implementation, the titanate catalyst in component B is a chelated titanate, and the titanate catalyst is selected from one or more of bis(acetylacetone) titanate diisopropyl and bis(acetoethyl) titanate diisopropyl.

[0034] By adopting the above technical solution, chelated titanates (such as diisopropyl bis(acetylacetonyl)titanate) can avoid self-condensation, remain stable in component B for a long time, and maintain high catalytic activity at room temperature. Its titanium ions, as strong Lewis acid centers, can quickly activate the silicon atoms of the crosslinking agent and work synergistically with 1,8-diazabicyclo(5.4.0)undec-7-ene to accelerate the curing reaction. At the same time, it does not contain organotin and meets the food-grade environmental certification requirements of LFGB, FDA, etc., thus expanding the application scenarios of adhesives (such as food contact material bonding).

[0035] Secondly, this application provides a method for preparing a fast-curing, environmentally friendly two-component silicone adhesive, using the following technical solution:

[0036] A method for preparing a fast-curing, environmentally friendly two-component silicone adhesive includes the following steps:

[0037] S1. Preparation of component A: Hydroxyl-terminated polydimethylsiloxane, inorganic filler and EPDM rubber-polydimethylsiloxane graft polymer are reacted under vacuum at 115-125℃. When the temperature is cooled to 30-40℃, an adhesion promoter, fumed silica and organic base catalyst are added under an inert atmosphere. After mixing evenly, the mixture is degassed under vacuum to obtain component A.

[0038] S2. Preparation of component B: Alkoxy-terminated polydimethylsiloxane, inorganic filler and color paste are reacted under vacuum at 115-125℃. When the temperature is cooled to 30-40℃, an adhesion promoter, crosslinking agent and titanate catalyst are added under an inert atmosphere. After mixing evenly, vacuum degassing is performed to obtain component B.

[0039] S3. Mix component A obtained in step S1 and component B obtained in step S2 at a volume ratio of 1:1 to obtain the two-component silicone adhesive.

[0040] The two-component silicone adhesive prepared using the above steps possesses excellent properties such as rapid curing, high toughness, and environmental friendliness. Specifically, the vacuum reaction at 115-125℃ effectively removes moisture and low-boiling-point impurities from the raw materials, avoiding catalyst deactivation or colloid thickening caused by moisture; the addition of heat-sensitive components such as catalysts and adhesion promoters at a low temperature of 30-40℃ prevents premature decomposition or reaction, ensuring maximum functionality of each component; mixing under an inert atmosphere prevents oxidation of active groups such as amino groups, and vacuum degassing ensures no air bubbles inside the colloid, improving bonding reliability and appearance quality; the step-by-step preparation and separate storage of components A and B prevent premature cross-linking, and they can be mixed in equal proportions before use, making the operation convenient and efficient.

[0041] In summary, this application includes at least one of the following beneficial technical effects:

[0042] 1. This application utilizes the synergistic combination of hydroxyl-terminated polydimethylsiloxane and alkoxy-terminated polydimethylsiloxane, and introduces EPDM-polydimethylsiloxane graft polymer as a toughness enhancer, which enables the two-component silicone adhesive to have excellent properties of rapid curing, high toughness, and environmental friendliness.

[0043] 2. This application uses 1,8-diazabicyclo(5.4.0)undec-7-ene as a strong organic base, in conjunction with the titanate catalyst in component B, to form an "acid-base synergistic catalysis" system, thereby achieving dual activation of nucleophiles and electrophiles, which drastically reduces the energy barrier of the condensation reaction and greatly improves the curing speed of the colloid.

[0044] 3. This application constructs a high-performance interface layer for the cured two-component silicone adhesive by rationally compounding acrylate-containing aminosilane dimers and hydroxyl-containing aminosilane dimers as adhesive promoters, which takes into account both polar and non-polar adhesive requirements and ensures a stable curing rate. Detailed Implementation

[0045] The present application will be further described in detail below with reference to embodiments and comparative examples:

[0046] Some of the raw materials used in the examples and comparative examples:

[0047] Vinyltrimethoxysilane (also known as: silane coupling agent JH-V171, CAS: 2768-02-7, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.); Fused silica powder (grade: FD-M30, particle size 1-3μm, purchased from Guangxi Yongjiu Mining Co., Ltd.); EPDM rubber powder (grade: 4045, purchased from Hefei Honglu Chemical Technology Co., Ltd.); Maleic anhydride (also known as maleic anhydride, CAS: 108-31-6); Sodium bentonite (montmorillonite content ≥85%, expanded 30 times, 400 mesh, purchased from Guangzhou Yifeng Chemical Technology Co., Ltd.);

[0048] 1,8-diazabicyclo[5.4.0]undec-7-ene (CAS: 6674-22-2), γ-aminopropyltrimethoxysilane (CAS: 13822-56-5), γ-acryloyloxypropyltrimethoxysilane (CAS: 21134-38-3), γ-aminopropyltriethoxysilane (CAS: 919-30-2), γ-glycidoxypropyltrimethoxysilane (CAS: 2530-83-8), methyltrimethoxysilane (CAS: 1185-55-3), and N-β-aminoethyl-γ-aminopropyltrimethoxysilane (CAS: 1760-24-3) were all purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0049] Hydroxyl-terminated polydimethylsiloxane (Catalog No.: R051288, purchased from Shanghai E. En Chemical Technology Co., Ltd.); Alkoxy-terminated polydimethylsiloxane (Model: F-40A, purchased from Jiangsu Kexing New Material Co., Ltd.); Fumed silica (hydrophobic fumed silica, specific surface area of ​​200-250 m² / g, Grade: R812S, purchased from Evonik Degussa Ltd.); Amino silicone oil (Model: Dow Corning OFX-8468, ammonia value of 0.6 mmol / g, purchased from Guangzhou Jucheng Zhaoye Organosilicon Raw Material Co., Ltd.); Pigment (Grade: RTV black pigment, purchased from Jiangxi Tai'en New Material Technology Co., Ltd.); Diisopropyl bis(acetylacetone)titanate (CAS: 17927-72-9, Product No.: 1182183, purchased from Tianjin Xiens Biochemical Technology Co., Ltd.).

[0050] Unless otherwise specified, all raw materials used in the examples and comparative examples are commercially available products.

[0051] Preparation Example 1

[0052] The preparation steps of fused silica powder with silane coupling agent surface modification are as follows:

[0053] 0.2 g of vinyltrimethoxysilane was dissolved in 20 mL of an aqueous ethanol solution (15 mL of ethanol and 5 mL of a mixed solvent), and 10 g of fused silica powder was added. The mixture was heated to 60°C at 150 rpm and stirred for 2 hours. After filtration, the mixture was washed twice with 5 mL of ethanol and dried under vacuum at 100°C for 2 hours to obtain fused silica powder with a silane coupling agent surface modified.

[0054] Preparation Example 2

[0055] The preparation steps of EPDM rubber-polydimethylsiloxane graft polymer are as follows:

[0056] 100 parts by weight of EPDM rubber powder, 5 parts by weight of maleic anhydride, and 0.8 parts by weight of dicumyl peroxide were placed in a mixer and mixed at 100°C for 10 minutes. The product was washed three times with acetone and dried under vacuum at 60°C for 6 hours to obtain maleic anhydride-grafted EPDM rubber. Under a nitrogen atmosphere, 50 parts by weight of hydroxyl-terminated polydimethylsiloxane, 10 parts by weight of hydroxyethyl methacrylate, 0.4 parts by weight of CuCl, and 0.8 parts by weight of 4,4-bispyridine were dissolved in 200 mL of toluene. 100 parts by weight of maleic anhydride-grafted EPDM rubber were added, and the mixture was heated to 80°C and reacted for 24 hours. The reaction solution was poured into excess methanol, and a solid precipitate appeared. After filtration, the solid was washed three times with methanol and dried under vacuum at 80°C for 12 hours to obtain EPDM rubber-polydimethylsiloxane graft polymer.

[0057] Preparation Example 3

[0058] The preparation steps of sodium-based bentonite modified with aminosilane are as follows:

[0059] 10g of sodium-based bentonite was added to 150mL of deionized water to form a bentonite aqueous suspension. 1.5g of γ-aminopropyltriethoxysilane was dissolved in 50mL of ethanol, and the pH of the solution was adjusted to 4.5 with 0.1mol / L hydrochloric acid aqueous solution. The solution was then poured into the bentonite aqueous suspension, heated to 60℃ and reacted for 3 hours. After filtration, the solution was washed three times with deionized water and dried under vacuum at 80℃ for 8 hours to obtain sodium-based bentonite with aminosilane surface modification.

[0060] Preparation Example 4

[0061] The preparation steps for acrylate-containing aminosilane dimers are as follows:

[0062] Under a nitrogen atmosphere, 18.0 g (0.1 mol) of γ-aminopropyltrimethoxysilane and 0.05 g of 1,8-diazabicyclo(5.4.0)undec-7-ene were dissolved in 80 mL of tetrahydrofuran. 24.7 g (0.12 mol) of γ-acryloyloxypropyltrimethoxysilane was added, and the mixture was heated to 80 °C and reacted for 5 hours. The tetrahydrofuran was removed by vacuum distillation, and 20 mL of methanol was added. The mixture was stirred at room temperature for 1 hour and then dried under vacuum at 110 °C for 12 hours to obtain an aminosilane dimer containing acrylate groups.

[0063] Preparation Example 5

[0064] The preparation steps for hydroxyl-containing aminosilane dimers are as follows:

[0065] Under a nitrogen atmosphere, 22.1 g (0.1 mol) of γ-aminopropyltriethoxysilane and 28.3 g (0.12 mol) of γ-glycidoxypropyltrimethoxysilane were added to 80 mL of toluene, heated to 80 °C and reacted for 3 hours. After rotary evaporation, the mixture was washed three times with deionized water and dried under vacuum at 110 °C for 12 hours to obtain a hydroxyl-containing aminosilane dimer. Example

[0066] Example 1

[0067] Preparation steps of two-component silicone adhesive:

[0068] S1. Preparation of Component A: 45 parts by weight of hydroxyl-terminated polydimethylsiloxane, 45 parts by weight of fused silica powder modified with silane coupling agent obtained in Preparation Example 1, 5.5 parts by weight of EPDM rubber-polydimethylsiloxane graft polymer obtained in Preparation Example 2, and 3 parts by weight of sodium bentonite modified with aminosilane surface obtained in Preparation Example 3 were reacted under vacuum at 120°C for 4 hours, and then cooled to 35°C. Under a nitrogen atmosphere, 3 parts by weight of amino silicone oil, 3 parts by weight of fumed silica, and 0.6 parts by weight of 1,8-diazabicyclo(5.4.0)undec-7-ene were added, mixed evenly, and then degassed under vacuum to obtain Component A.

[0069] S2. Preparation of Component B: 45 parts by weight of alkoxy-terminated polydimethylsiloxane, 35 parts by weight of nano-calcium carbonate and 5.5 parts by weight of color paste were reacted under vacuum at 120°C for 4 hours, and then cooled to 35°C. Under a nitrogen atmosphere, 1.5 parts by weight of the acrylate-containing aminosilane dimer prepared in Preparation Example 4, 1.5 parts by weight of the hydroxyl-containing aminosilane dimer prepared in Preparation Example 5, 10 parts by weight of methyltrimethoxysilane and 0.6 parts by weight of diisopropyl bis(acetylacetonate)titanate were added and mixed evenly. After vacuum degassing, Component B was obtained.

[0070] S3. Mix component A obtained in step S1 and component B obtained in step S2 at a volume ratio of 1:1 to obtain a two-component silicone adhesive.

[0071] Example 2

[0072] The difference between Example 2 and Example 1 is that in step S2 of Example 2, 1.5 parts by weight of the acrylate-containing aminosilane dimer prepared in Example 4 and 1.5 parts by weight of the hydroxyl-containing aminosilane dimer prepared in Example 5 are replaced with 2 parts by weight of the acrylate-containing aminosilane dimer prepared in Example 4 and 1 part by weight of the hydroxyl-containing aminosilane dimer prepared in Example 5.

[0073] Example 3

[0074] The difference between Example 3 and Example 1 is that in step S2 of Example 3, 1.5 parts by weight of the acrylate-containing aminosilane dimer prepared in Example 4 and 1.5 parts by weight of the hydroxyl-containing aminosilane dimer prepared in Example 5 are replaced with 1 part by weight of the acrylate-containing aminosilane dimer prepared in Example 4 and 2 parts by weight of the hydroxyl-containing aminosilane dimer prepared in Example 5.

[0075] Example 4

[0076] The difference between Example 4 and Example 1 is that in step S2 of Example 4, 1.5 parts by weight of the acrylate-containing aminosilane dimer prepared in Example 4 and 1.5 parts by weight of the hydroxyl-containing aminosilane dimer prepared in Example 5 are replaced with 3 parts by weight of the acrylate-containing aminosilane dimer prepared in Example 4.

[0077] Example 5

[0078] The difference between Example 5 and Example 1 is that in step S2 of Example 5, 1.5 parts by weight of the acrylate-containing aminosilane dimer prepared in Example 4 and 1.5 parts by weight of the hydroxyl-containing aminosilane dimer prepared in Example 5 are replaced with 3 parts by weight of the hydroxyl-containing aminosilane dimer prepared in Example 5.

[0079] Example 6

[0080] The difference between Example 6 and Example 1 is that in step S2 of Example 6, 1.5 parts by weight of the acrylate-containing aminosilane dimer prepared in Example 4 and 1.5 parts by weight of the hydroxyl-containing aminosilane dimer prepared in Example 5 are replaced with 3 parts by weight of N-β-aminoethyl-γ-aminopropyltrimethoxysilane.

[0081] Comparative Example 1

[0082] The only difference between Comparative Example 1 and Example 1 is that in step S2 of Comparative Example 1, 45 parts by weight of alkoxy-terminated polydimethylsiloxane were replaced with 45 parts by weight of hydroxyl-terminated polydimethylsiloxane.

[0083] Comparative Example 2

[0084] The only difference between Comparative Example 2 and Example 1 is that in step S1 of Comparative Example 2, 45 parts by weight of hydroxyl-terminated polydimethylsiloxane were replaced with 45 parts by weight of alkoxy-terminated polydimethylsiloxane.

[0085] Comparative Example 3

[0086] The only difference between Comparative Example 3 and Example 1 is that 5.5 parts by weight of the EPDM-polydimethylsiloxane grafted polymer prepared in Example 2 were not added in step S1 of Comparative Example 3.

[0087] Comparative Example 4

[0088] The only difference between Comparative Example 4 and Example 1 is that in step S2 of Comparative Example 4, 0.6 parts by weight of bis(acetylacetonyl)titanate diisopropyl ester is replaced with 0.6 parts by weight of 1,8-diazabicyclo(5.4.0)undec-7-ene.

[0089] Comparative Example 5

[0090] The only difference between Comparative Example 5 and Example 1 is that in step S1 of Comparative Example 5, 0.6 parts by weight of 1,8-diazabicyclo(5.4.0)undec-7-ene is replaced with 0.6 parts by weight of diisopropyl bis(acetylacetonyl)titanate.

[0091] The two-component silicone adhesives prepared in each embodiment and comparative example were tested for curing speed and curing performance according to the following international standards:

[0092] Test Project International Standards Standard Name Thixotropic index GB / T 2794-2013 Determination of adhesive viscosity using a single-cylinder rotational viscometer method Surface drying time GB / T 13477.5-2002 Test methods for building sealant materials, Part 5: Determination of surface drying time hardness GB / T 531.1-2008 Methods for testing the indentation hardness of vulcanized or thermoplastic rubber - Part 1 - Shore hardness test Tensile shear strength GB / T 7124-2008 Determination of tensile shear strength of adhesives (rigid material vs. rigid material) Tensile strength GB / T 528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber Adhesion GB / T16997-1997 Representation of the main failure types of adhesives

[0093] The thixotropic index is defined as TI = low-speed viscosity / high-speed viscosity; the LFGB and FDA tests on the two-component silicone adhesives prepared in each embodiment and comparative example were conducted by the third-party testing organization SGS.

[0094] The test results are summarized in Table 1.

[0095] Table 1. Performance test data of the two-component silicone adhesives prepared in each embodiment and comparative example.

[0096] Test Project Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Thixotropic index 5.4 5.5 5.5 5.4 5.3 5.3 5.4 5.4 5.3 5.6 5.4 Surface drying time (min) 7 8 8 9 9 8 21 29 8 40 39 Tensile shear strength (MPa) after 1 hour of curing 1.55 1.56 1.45 1.60 1.56 1.21 0.14 0.23 1.22 0.01 0.01 Hardness (Shore A) 56 55 54 56 55 55 44 60 56 45 47 Tensile strength (MPa) 3.88 3.75 3.72 3.80 3.82 3.68 2.38 2.59 3.20 3.11 3.33 Al-Al tensile shear strength (MPa) 3.47 2.52 2.50 2.48 2.54 2.69 1.93 2.00 2.91 3.01 3.07 Aluminum alloy adhesion CF CF CF CF CF CF / AF CF CF CF CF CF ABS adhesion CF CF / AF CF / AF CF / AF CF / AF AF CF / AF CF CF CF CF Ink glass adhesion CF CF / AF CF / AF CF / AF CF / AF AF AF CF CF CF CF LFGB testing conform to conform to conform to conform to conform to conform to conform to conform to conform to conform to conform to FDA testing conform to conform to conform to conform to conform to conform to conform to conform to conform to conform to conform to

[0097] Combining Examples 1 and 2-6 with Table 1, it can be seen that the test performance of Example 1 is better than that of Examples 2-6. This may be because in Example 1, the acrylate-containing aminosilane dimer and the hydroxyl-containing aminosilane dimer in component B are matched in a 1:1 mass ratio. This ratio can achieve the optimal synergistic effect—the hydrophobic interface protection effect of the acrylate-containing aminosilane dimer and the crosslinking density enhancement effect of the hydroxyl-containing aminosilane dimer are balanced, which not only ensures the stability of the interface adhesion but also promotes the density and uniformity of the crosslinking network. In contrast, in Example 2 (acrylate-containing aminosilane dimer: hydroxyl-containing aminosilane dimer = 2:1), the acrylate-containing aminosilane dimer is excessive, and in Example 3 (acrylate-containing aminosilane dimer: hydroxyl-containing aminosilane dimer = 1:2), the hydroxyl-containing aminosilane dimer is excessive. This reduces the adhesion strength to the aluminum alloy substrate, weakens the adhesion applicability, and makes it impossible to achieve complete cohesion for the adhesion of ink glass and ABS. Example 6 uses only the commercially available coupling agent KH-792 as an adhesion promoter and is not suitable for bonding ABS plastic and ink glass.

[0098] The weakening of the hydrophobic protection effect at the interface resulted in a slightly inferior surface drying speed, hardness, and mechanical properties compared to Example 1.

[0099] Based on Example 1, Comparative Examples 1-2, and Table 1, it can be seen that the test performance of Example 1 is superior to that of Comparative Examples 1-2. This may be because Example 1 uses a compound system of hydroxyl-terminated polydimethylsiloxane and alkoxy-terminated polydimethylsiloxane. Alkoxy-terminated polydimethylsiloxane can react directly with water without waiting for pre-activation of the crosslinking agent, which greatly accelerates the reaction start-up speed. In contrast, Comparative Example 1 uses a single hydroxyl-terminated polydimethylsiloxane, and Comparative Example 2 uses a single alkoxy-terminated polydimethylsiloxane, which results in slow reaction start-up, insufficient curing, significantly prolonged surface drying time, and insufficient crosslinking network density, which in turn leads to a significant decrease in hardness, tensile strength, and lap shear strength.

[0100] Based on Example 1 and Comparative Example 3, and referring to Table 1, it can be seen that the test performance of Example 1 is better than that of Comparative Example 3. This may be because EPDM-polydimethylsiloxane graft polymer was added to component A of Example 1. As a flexible reinforcing phase, this polymer can not only improve the mechanical strength of the colloid, but also form a good synergistic effect with the organosilicon matrix and filler, promoting the densification of the crosslinking network. In contrast, Comparative Example 3 did not add this graft polymer, resulting in insufficient support of the colloid structure and poor uniformity of the crosslinking network, leading to varying degrees of decline in all performance aspects.

[0101] Based on Example 1, Comparative Examples 4-5, and Table 1, it can be seen that the test performance of Example 1 is superior to that of Comparative Examples 4-5. This may be because Example 1 uses an acid-base synergistic catalytic system of 1,8-diazabicyclo(5.4.0)undec-7-ene and chelated titanate. 1,8-diazabicyclo(5.4.0)undec-7-ene activates the silanol groups, and titanate activates the silicon centers of the crosslinking agent. The dual activation significantly reduces the reaction energy barrier and accelerates the curing reaction and the formation of the crosslinking network. In contrast, Comparative Examples 4 and 5 both use a single catalytic system, which cannot achieve the dual activation effect, resulting in a slower curing speed, lower crosslinking density, and lower hardness and mechanical properties compared to Example 1.

[0102] This application utilizes the synergistic combination of hydroxyl-terminated polydimethylsiloxane and alkoxy-terminated polydimethylsiloxane, combined with an acid-base synergistic catalytic system of 1,8-diazabicyclo(5.4.0)undec-7-ene and chelated titanate, and introduces EPDM-polydimethylsiloxane graft polymer as a toughening enhancer, to enable the two-component silicone adhesive to possess excellent properties such as rapid curing, high toughness, and environmental friendliness.

[0103] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A fast-curing, environmentally friendly two-component silicone adhesive, characterized in that, The product comprises component A and component B. Component A includes the following components in parts by weight: 30-60 parts of hydroxyl-terminated polydimethylsiloxane, 30-60 parts of inorganic filler, 1-10 parts of polyolefin elastomer-organosilicone graft polymer, 1-5 parts of amino silicone oil, 1-5 parts of fumed silica, and 0.2-1 parts of organic base catalyst. Component B includes the following components in parts by weight: 30-60 parts of alkoxy-terminated polydimethylsiloxane, 20-50 parts of inorganic filler, 1-10 parts of color paste, 1-5 parts of adhesion promoter, 5-15 parts of crosslinking agent, and 0.2-1 parts of titanate catalyst. The polyolefin elastomer-organosilicone graft polymer is an ethylene propylene diene monomer (EPDM) rubber-polydimethylsiloxane graft polymer. The adhesion promoter in component B includes an acrylate-containing aminosilane dimer and a hydroxyl-containing aminosilane dimer; the mass ratio of the two is 1:(0.8-1.2). The organic base catalyst in component A is 1,8-diazabicyclo(5.4.0)undec-7-ene; The titanate catalyst in component B is a chelated titanate. The preparation steps of the acrylate-containing aminosilane dimer are as follows: Under a nitrogen atmosphere, 18.0 g of γ-aminopropyltrimethoxysilane and 0.05 g of 1,8-diazabicyclo(5.4.0)undec-7-ene were dissolved in 80 mL of tetrahydrofuran. 24.7 g of γ-acryloyloxypropyltrimethoxysilane was added, and the mixture was heated to 80 °C and reacted for 5 hours. The tetrahydrofuran was removed by vacuum distillation, and 20 mL of methanol was added. The mixture was stirred at room temperature for 1 hour and then dried under vacuum at 110 °C for 12 hours to obtain an aminosilane dimer containing acrylate groups. The preparation steps of the hydroxyl-containing aminosilane dimer are as follows: Under a nitrogen atmosphere, 22.1 g of γ-aminopropyltriethoxysilane and 28.3 g of γ-glycidoxypropyltrimethoxysilane were added to 80 mL of toluene, heated to 80 °C and reacted for 3 hours. After rotary evaporation, the mixture was washed three times with deionized water and dried under vacuum at 110 °C for 12 hours to obtain a hydroxyl-containing aminosilane dimer.

2. The fast-curing, environmentally friendly two-component silicone adhesive according to claim 1, characterized in that, The inorganic filler in component A is fused silica powder with a surface modified by a silane coupling agent.

3. The rapid-curing, environmentally friendly two-component silicone adhesive according to claim 1, characterized in that, The amino silicone oil in component A has an ammonia value of 0.2-0.6 mmol / g.

4. The rapid-curing, environmentally friendly two-component silicone adhesive according to claim 1, characterized in that, Component A also includes sodium-based bentonite that has been surface-modified with aminosilane.

5. The rapid-curing, environmentally friendly two-component silicone adhesive according to claim 1, characterized in that, The crosslinking agent in component B is selected from one or more of methyltrimethoxysilane, tetramethoxysilane, vinyltrimethoxysilane, tetraethoxysilane, and vinyltriethoxysilane.

6. The rapid-curing, environmentally friendly two-component silicone adhesive according to claim 1, characterized in that, The titanate catalyst is selected from one or more of bis(acetylacetonyl) titanate diisopropyl and bis(acetoethyl) titanate diisopropyl.

7. A method for preparing a rapid-curing, environmentally friendly two-component silicone adhesive according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Preparation of component A: Hydroxyl-terminated polydimethylsiloxane, inorganic filler and EPDM rubber-polydimethylsiloxane graft polymer are reacted under vacuum at 115-125℃. When the temperature is cooled to 30-40℃, amino silicone oil, fumed silica and organic base catalyst are added under an inert atmosphere. After mixing evenly, vacuum degassing is performed to obtain component A. S2. Preparation of component B: Alkoxy-terminated polydimethylsiloxane, inorganic filler and color paste are reacted under vacuum at 115-125℃. When the temperature is cooled to 30-40℃, an adhesion promoter, crosslinking agent and titanate catalyst are added under an inert atmosphere. After mixing evenly, vacuum degassing is performed to obtain component B. S3. Mix component A obtained in step S1 and component B obtained in step S2 at a volume ratio of 1:1 to obtain the two-component silicone adhesive.