A high-strength modified silane adhesive for bonding metal substrates, and a method of preparing and using the same

Abstract

This invention relates to the field of adhesive technology, specifically to a high-strength modified silane adhesive for bonding metal substrates and its preparation method. The modified silane adhesive comprises the following components in parts by weight: 2060 parts of silane-modified polymer base resin, 230 parts of reinforcing silicone resin, 115 parts of phosphate-containing modified silane compound, 120 parts of active plasticizer, 0.54 parts of dehydrating agent, 0.56 parts of adhesion promoter, 575 parts of filler, 0.58 parts of thixotropic agent, and 0.011 parts of catalyst. The beneficial effects of this invention are: the molecular chain of the phosphate-containing modified silane compound simultaneously contains phosphate groups that can strongly anchor to the hydroxyl groups on the metal surface and silanoxy groups that can participate in cross-linking reactions, solving the problems of poor compatibility and easy migration between traditional phosphate ester additives and silicone systems. The modified silane adhesive provided by this invention is a single-component solvent-free product, requiring no pre-coating primer, and exhibits a tensile shear strength ≥4 MPa, a Shore D hardness ≥35, and a double 85 aging retention rate ≥90% after moisture curing.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, specifically to a high-strength modified silane adhesive for bonding metal substrates, its preparation method, and its application. Background Technology

[0002] Silane-modified polymers (SMPs) are a class of polymers with polyethers, polyacrylates, polyurethanes, epoxy resins, etc., as the main chain, modified with siloxanes at both ends. Among them, silane-modified polyethers (MS) are the most widely used. Compared with traditional polyurethane and epoxy adhesives, MS adhesives have excellent weather resistance, durability, high and low temperature resistance, and low viscosity and environmental friendliness. Currently, MS adhesives are widely used in the construction field, such as glass adhesives, wood glues, grout sealants, and nail-free adhesives. In addition, silane-modified polymers are also gradually appearing in the bonding, sealing, and potting of components in the fields of rail transportation, automobiles and ships, container manufacturing, and electronic equipment. However, ordinary one-component MS adhesives have insufficient bonding strength, especially for metal substrates. The bonding strength of commonly available MS adhesives is <2.5MPa, which greatly limits its promotion and application in the field of metal substrate bonding.

[0003] To improve the adhesion performance of MS adhesive to metal substrates, various technical solutions have been proposed in the prior art. Chinese patent application CN117586735A discloses a high-strength single-component MS anti-mildew and nail-free adhesive and its preparation method. It is mainly composed of polyether polymer, plasticizer, nanofiller, bulk filler, light stabilizer, tackifier, antibacterial and anti-mildew agent, etc. However, its 24-hour tensile shear strength is <2MPa and its 168-hour tensile shear strength is <3MPa under standard conditions, which is still not suitable for structural adhesives with higher bonding strength requirements.

[0004] Chinese patent application CN116144309B discloses a high-strength, moisture- and heat-resistant two-component MS adhesive and its preparation method. The tensile strength of the metal substrate is >4.5MPa. However, the MS adhesive is a two-component adhesive and needs to be mixed evenly before use, which has problems such as mixing ratio error and operation time limit.

[0005] Chinese patent application CN112552870A discloses a high-strength, high-hardness, UV / moisture dual-curing MS adhesive and its preparation method, with a final tensile strength ≥3.8MPa and shear strength ≥5.8MPa. However, this MS adhesive requires a UV / moisture dual-curing method and is not suitable for bonding non-transparent substrates.

[0006] Chinese patent application CN104559758A discloses a primer for silane-modified polyether sealant and its preparation method. The primer enhances the bonding strength between the silane-modified polyether sealant and the substrate. However, the primer contains a large amount of solvent, which poses a potential health hazard to workers and presents a clear occupational safety risk.

[0007] Chinese patent application CN120843040A discloses a one-component modified silane adhesive, which also aims for good adhesion to substrates such as metals, and uses silane-modified polyether resin and silane-modified polymer resin. However, the aforementioned adhesion-promoting scheme relies on conventional coupling agents (such as amino and epoxy silanes) and does not involve the specific structure of phosphate-containing silane-modified polyether synthesized through molecular design, nor does it mention the use of a ternary synergistic system of multifunctional reinforcing silicone resin and reactive plasticizer.

[0008] Chinese patent application CN1125139C discloses an organopolysiloxane composition that can be crosslinked by alcohol removal to form an elastomer, wherein an acidic phosphate ester is used as a catalyst / stabilizer in the organopolysiloxane composition. However, the design purpose (catalysis, surface activity) of the phosphate ester compound is completely different from that of this application, and it does not mention its use as an adhesion promoter in conjunction with reinforcing silicone resin and active plasticizer in MS adhesive system for high-strength metal bonding.

[0009] In summary, the existing technology still lacks a single-component, solvent-free, primer-free modified silane adhesive product that can achieve high-strength bonding to metal substrates and also has excellent resistance to humid heat aging. Summary of the Invention

[0010] The technical problem to be solved by the present invention is to provide a high-strength modified silane adhesive for bonding metal substrates, its preparation method and application, which solves the technical problems of insufficient bonding strength of existing MS adhesives to metal substrates, the need for primer or two-component construction, and poor aging resistance.

[0011] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A high-strength modified silane adhesive for bonding metal substrates is provided, characterized in that it comprises the following components in the following weight ratios: Component A1: 20-60 parts of silane-modified polymer base resin; Component A2: 2-30 parts of reinforcing silicone resin; Component A3: 1-15 parts of a phosphate-modified silane compound; Component A4: 1-20 parts of active plasticizer; Component A5: 0.5-4 parts of dehydrating agent; Component A6: Adhesion promoter 0.5-6 parts; Component A7: 5-75 parts of filler; Component A8: 0.5-8 parts of thixotropic agent; Component A9: 0.01-1 part catalyst; The molecular chain of the phosphate-containing modified silane compound contains both phosphate groups and hydrolyzable silane groups.

[0012] Furthermore, the high-strength modified silane adhesive for bonding metal substrates described above is composed of the following components by weight percentage: Component A1: 20-60% silane-modified polymer base resin; Component A2: 2-30% reinforcing silicone resin; Component A3: 1-15% of phosphate-modified silane compounds; Component A4: 1-20% reactive plasticizer; Component A5: Dehydrating agent 0.5-4%; Component A6: Adhesion promoter 0.5-6%; Component A7: 5-75% filler; Component A8: Thixotropic agent 0.5-8%; Component A9: Catalyst 0.01-1%; Component A10: 0.2-2% other additives.

[0013] Furthermore, in the above-mentioned high-strength modified silane adhesive for bonding metal substrates, the phosphate-containing modified silane compound is a phosphate-containing silane-modified polyether, prepared by reacting the following raw materials: Component I: Alkenyl phosphate ester; Component II: Tertiary amine; Component III: Polyetheramine; the ratio of the primary amino equivalent in the polyetheramine to the C=C double bond equivalent in Component I is 1:1.2 to 1.2:1; Component IV: Reactive silane coupling agent; the ratio of the equivalent of the group that can react with the secondary amine group in the reactive silane coupling agent to the equivalent of the primary amine group in Component III is 1:1.2 to 1.2:1.

[0014] As can be seen from the above, this limitation clarifies the molecular construction path of the key adhesion promoter: through Michael addition and subsequent functional group reactions, the phosphate anchoring group and the silane crosslinking group are introduced into the same molecular chain by chemical bonding, which ensures the synergistic function of the two and avoids the risk of phase separation caused by physical mixing, thus providing the adhesive with stable and efficient metal adhesion.

[0015] Furthermore, in the above-mentioned high-strength modified silane adhesive for bonding metal substrates, component I is the reaction product of hydroxyethyl (meth)acrylate and phosphate ester, or the reaction product of ethoxylated / propoxylated hydroxyethyl (meth)acrylate and phosphate ester; Component II is triethylamine; Component III is an aliphatic primary amine modified polypropylene glycol with an average molar mass of 200-2000 Daltons. Component IV is an epoxy-containing silane coupling agent or an isocyanate-containing silane coupling agent.

[0016] As shown above, specific selections were made for the four raw materials used to prepare phosphate-containing modified silane compounds. Hydroxyethyl methacrylate phosphate or its alkoxylated product is preferred as an olefinic phosphate ester, providing suitable reactivity and compatibility. Triethylamine is used as a neutralizing agent to adjust the pH of the system to neutral, preventing premature hydrolysis of silanes and significantly improving the storage stability of the product. Polyetheramines with an average molar mass of 200-2000 Daltons are selected to balance flexibility and reactivity. Silane coupling agents containing epoxy or isocyanate groups are selected to ensure efficient coupling with polyetheramine intermediates, ultimately obtaining a target product with a well-defined structure and stable performance.

[0017] Furthermore, in the above-mentioned high-strength modified silane adhesive for bonding metal substrates, component A1 is a polymer with at least two alkoxysilane groups at both ends, and the polymer is polyether, polyester, polycarbonate, polyurethane, polyacrylate, polybutadiene, polypentadiene, or epoxy resin.

[0018] As can be seen from the above, the above limitations not only clearly define the crosslinking properties (polyalkoxy groups at both ends) that the base resin must possess, but also retain the diversity of the main chain structure, so that the adhesive of the present invention can select a suitable base resin according to specific application requirements (such as flexibility, weather resistance, oil resistance, etc.), thus expanding the scope of application of the present invention.

[0019] Furthermore, in the above-mentioned high-strength modified silane adhesive for bonding metal substrates, component A2 is a polyhedral polysilsesquioxane resin with an alkoxy content of 1-50 wt%, wherein the polyhedral polysilsesquioxane resin is one or more of a methoxy-containing methyl silicone resin, a methoxy-containing methylphenyl silicone resin, or a methoxy-containing phenyl silicone resin.

[0020] As can be seen from the above, the aforementioned reinforcing silicone resin is polyhedral polysilsesquioxane, and its alkoxy content is specified to be 1-50 wt%. POSS has a unique cage-like three-dimensional structure and excellent compatibility with the base resin. Its high content of reactive alkoxy groups can form a three-dimensional network with high cross-linking density during moisture curing, significantly improving the cohesive strength, hardness, and heat resistance of the colloid. At the same time, its nanoscale reinforcing effect can be uniformly dispersed, avoiding the stress concentration problem that may be caused by traditional fillers.

[0021] Furthermore, in the above-mentioned high-strength modified silane adhesive for bonding metal substrates, component A4 is a single-terminal silane compound or a single-terminal siloxane modified polymer with hydrolytic reactivity.

[0022] As can be seen from the above, the aforementioned limited reactive plasticizers are single-terminated silane compounds or single-terminated siloxane-modified polymers with hydrolytic reactivity. These plasticizers contain a silane group that can participate in cross-linking reactions, and during curing, they can chemically bond to the three-dimensional network, avoiding the performance degradation (such as modulus reduction and adhesion loss) caused by physical migration of traditional inert plasticizers under high temperature and high humidity conditions. This significantly improves the long-term durability and environmental adaptability of the adhesive.

[0023] Furthermore, the above-mentioned high-strength modified silane adhesive for bonding metal substrates includes at least one of the following technical features: Component A5 is one or more of siloxane compounds, monoisocyanate compounds, or oxazolidine compounds; Component A6 is a silane coupling agent containing functional groups, wherein the functional groups are mercapto, epoxy, or amino. The component A7 is calcium carbonate whose surface has been treated with fatty acid, titanate coupling agent or silane coupling agent; The component A8 is fumed silica; The component A9 is an organotin compound, an organotitanium compound, a tertiary amine compound, or a nitrogen-containing heterocyclic compound; The component A10 is a light stabilizer and an antioxidant.

[0024] As can be seen from the above, the aforementioned dehydrating agents are siloxanes, monoisocyanates, or oxazolidine compounds. These dehydrating agents can preferentially react with trace amounts of moisture in the system, effectively inhibiting the premature hydrolysis of isocyanate groups or silanoxy groups, thereby significantly improving the storage stability of the single-component system and ensuring that the product maintains stable viscosity and curing properties during storage.

[0025] The adhesion promoters are specified as silane coupling agents containing thiol, epoxy, or amino functional groups. These functional groups can specifically interact with active sites on the metal surface or other components in the coating, further enhancing interfacial adhesion and forming a multiple anchoring effect with phosphate-modified silane compounds, jointly ensuring reliable adhesion to the metal substrate.

[0026] The filler is limited to calcium carbonate surface-treated with fatty acids, titanates, or silane coupling agents. Surface treatment significantly improves the compatibility and dispersibility of calcium carbonate with the organic resin matrix, preventing filler agglomeration; at the same time, the high specific surface area (BET≥50m² / g) of calcium carbonate can form sufficient physical or chemical interactions with the resin matrix, resulting in a reinforcing and toughening effect and improving the mechanical properties of the adhesive.

[0027] The types of thixotropic agents and catalysts are limited. Fumed silica is selected as the thixotropic agent, which can maintain high viscosity under low shear to prevent sagging, and reduce viscosity under high shear to facilitate construction. Organotin, organotitanium, tertiary amines or nitrogen-containing heterocyclic compounds are selected as catalysts, which can effectively catalyze the hydrolysis and polycondensation reaction of siloxanes, ensuring that the adhesive cures within the expected time and establishes sufficient initial strength and final performance.

[0028] The A10 specification includes light stabilizers and antioxidants. The introduction of these two types of additives can effectively delay the molecular chain degradation, yellowing, and performance degradation of adhesives caused by ultraviolet radiation and thermo-oxidative aging during long-term outdoor use, significantly improving the service life and appearance retention of the coating in harsh environments.

[0029] Another technical solution provided by the present invention is: a method for preparing the above-mentioned high-strength modified silane adhesive for bonding metal substrates, comprising the following steps: S1: Mix components A1, A2, A3, A4, A5 and component A10 evenly to obtain the first mixture; S2: Add component A7 and component A8 to the first mixture and disperse under vacuum to obtain a second mixture; S3: Add component A6 and component A9 to the second mixture, mix evenly, and then degas under vacuum conditions to obtain the high-strength modified silane adhesive.

[0030] As shown above, the method employs a step-by-step mixing process: first, the resin and functional additives are premixed uniformly; then, fillers and thixotropic agents are added and subjected to high-shear vacuum dispersion to eliminate air bubbles and fully wet the powder; finally, moisture-sensitive coupling agents and catalysts are added and vacuum degassing is performed. This scientifically sequenced process ensures uniform dispersion of each component, avoids side reactions, and thoroughly removes air bubbles, thereby guaranteeing the storage stability, workability, and mechanical properties of the final product after curing.

[0031] Another technical solution provided by the present invention is: the application of the above-mentioned high-strength modified silane adhesive for bonding metal substrates in bonding metal substrates.

[0032] The beneficial effects of this invention are as follows: A phosphate-containing silane-modified polyether is synthesized in situ through molecular design, resulting in a molecular chain containing both phosphate groups that can strongly anchor to hydroxyl groups on metal surfaces and silanoxy groups that can participate in the crosslinking of silicone systems. This fundamentally solves the problems of poor compatibility and easy migration between traditional phosphate ester additives and silicone systems. Furthermore, it is synergistically compounded with multifunctional reinforcing silicone resins (especially POSS) and reactive plasticizers to construct a high-strength modified silane adhesive system that requires no primer, is solvent-free, and is a single-component moisture-curing agent. Specifically: (1) The high-strength modified silane adhesive of the present invention introduces silane modified polyether containing phosphate ester, whose phosphate groups can form covalent bonds with the hydroxyl groups on the metal surface, which greatly improves the adhesion of silicone to the metal substrate, thereby improving the bonding strength and tensile shear strength of the adhesive.

[0033] (2) Compared with common phosphate ester adhesion promoters such as epoxy phosphate esters (such as Lubrizol 2065) and polyester phosphate esters (such as Lubrizol 2063), the phosphate ester-containing silane modified polyether of the present invention has good compatibility with silicone and can react with silicone to form crosslinks to further improve the bonding strength.

[0034] (3) The high-strength modified silicone of the present invention introduces a reactive multifunctional group to enhance the cohesive strength of the silicone. At the same time, it uses an active plasticizer to replace the traditional non-reactive plasticizer such as dibutyl phthalate, which can reduce the problem of decreased adhesion caused by plasticizer migration.

[0035] (4) The high-strength modified silicone of the present invention is a single-component solvent-free product, which is convenient to apply and environmentally friendly. No pre-coating is required. After water vapor curing, the tensile shear strength of the product is ≥4 MPa and the hardness exceeds Shore D30, making it suitable for bonding high-strength metal substrates. Detailed Implementation

[0036] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments.

[0037] This invention provides a high-strength modified silane adhesive for bonding metal substrates, comprising the following components: Component A1: A silane-modified polymer base resin; Component A2: A reinforcing silicone resin; Component A3: A silane-modified polyether containing phosphate esters; Component A4: An active plasticizer; Component A5: A dehydrating agent; Component A6: An adhesion promoter; Component A7: A type of filler; Component A8: A thixotropic agent; Component A9: A catalyst; Component A10: Other additives The component A1 silane-modified polymer base resin refers to a polymer modified with at least two alkoxysilanes at both ends. The silane-modified polymer can be selected from polyether, polyester, polycarbonate, polyurethane, polyacrylate, polybutadiene, polypentadiene, and epoxy resin.

[0038] When the polymer is a polyether, specific examples of silane-modified polyether compounds can be selected from Wacker Chemie's GENIOSIL STP-E10, GENIOSIL STP-E15, GENIOSIL STP-E35, GENIOSIL STP-E30, Kaneka Chemical's S303H, S203H, SAX350, SAX260, Asahi Glass's EXCESTAR S2410E, and EXCESTAR S2420E.

[0039] When the polymer is polyurethane, specific examples of silane-modified polyurethane compounds can be selected from Momentive SPUR+1015LM, SPUR+1050MM, Covestro Desmoseal S XP 2774, and Desmoseal S XP2636.

[0040] When the polymer is polyacrylate, specific examples of silane-modified polyacrylate compounds can be selected from Zhongyuan Chemical's MAX602, MAX923, MA451, and MA452.

[0041] When the polymer is polybutadiene, specific examples of silane-modified polybutadiene compounds can be selected from Evonik Chemicals POLYVESTST-E 60.

[0042] The silane-modified polymer has a number-average molecular weight of 200-40,000 Daltons, preferably 1,000-30,000 Daltons, more preferably 2,000-20,000 Daltons, and the component Al silane-modified polymer base resin accounts for 20-60% of the total weight of the modified silicone, preferably 25-55%, more preferably 30-50%.

[0043] The A2 reinforcing silicone resin is a polysiloxane resin containing two or more reactive groups. Generally, the silicone resin structure is a linear, branched two-dimensional structure or a multi-faceted three-dimensional structure. The reactive groups can be selected from one or more of alkoxy, amino, epoxy, and silanol groups. Preferably, the reactive group is alkoxy, and more preferably, it is methoxy. The terminal or branched non-reactive groups can be selected from one or more of methyl, ethyl, propyl, butyl, phenyl, and isooctyl groups. Preferably, it is one or two of methyl and phenyl groups.

[0044] According to one embodiment, the siloxane resin is a polyhedral polysilsesquioxane resin (POSS silicone resin), wherein the alkoxy groups account for 1-50% of the total weight of the polysilsesquioxane resin, preferably 5-40%, and more preferably 10-30%.

[0045] The polysilsesquioxane resin has a number-average molecular weight Mn of 300-10000 Daltons, preferably 500-5000 Daltons, and more preferably 800-3000 Daltons.

[0046] As a preferred example for commercialization, the polysilsesquioxane resin may be selected from methoxylated methyl silicone resins, such as Wacker SILRES MSE 100, Dow DOWSIL 2405, Dow DOWSIL US-CF-2403, Evonik SILIKOPHEN AC 1000, and Evonik SILIKOPHEN AC 900.

[0047] The polysilsesquioxane resin may also be selected from methoxylated methylphenyl silicone resins, such as Wacker SILRESIC232, Wacker SILRES SY231, Wacker SILRES IC368, Dow DOWSIL 3037, and Dow DOWSIL 3074.

[0048] The polysilsesquioxane resin may also be selected from methoxylated phenyl silicone resins, such as Wacker SILRES IC678.

[0049] As described above, polysilsesquioxane with a polyhedral structure has a high methoxy content and can form a high cross-linking density three-dimensional network structure after water vapor curing. This can effectively improve the strength of the silane-modified polymer base resin of component A1. At the same time, it has low viscosity and good compatibility with component A1, making it very suitable for this system.

[0050] The component A2 reinforcing silicone resin accounts for 2-30% of the total weight of the modified silicone, preferably 4-25%, and more preferably 6-20%.

[0051] Component A3 is a silane-modified polyether containing phosphate esters, which is obtained by reacting the following substances: Component I: An olefinic phosphate ester; Component II: A tertiary amine; Component III: A polyetheramine; Component IV: A reactive silane coupling agent; As described above, olefinic phosphate esters undergo Michael addition with polyetheramines to form phosphate ester modified polyethers with secondary amine groups. The secondary amine groups then react with silane coupling agents to obtain the final product, silane modified polyether containing phosphate esters. Compared with traditional epoxy phosphate ester adhesion promoters, this polymer backbone, being silane modified polyether, has excellent compatibility with silicone systems. The phosphate ester groups on the side chains can form strong anchors with metal substrates, thereby generating high bonding strength.

[0052] Component I, the olefinic phosphate ester, can be selected from the reaction product of hydroxyethyl (meth)acrylate and phosphate ester, with specific commercial products including Solvay Sipomer PAM-4000 and Xianchuang Chemical Harcryl 1228M.

[0053] In another embodiment, the component I olefinic phosphate ester may be selected from the reaction product of ethoxylated or propoxylated hydroxyethyl methacrylate and phosphate ester, and specific commercial products may be selected from Solvay Sipomer PAM-100, Sipomer PAM-200, and Sipomer PAM-300.

[0054] Preferably, component I should have lower viscosity and lower color; more preferably, component I is Solvay Sipomer PAM-4000.

[0055] Component II is a tertiary amine, which adjusts the acidity or alkalinity of component I to achieve neutrality, reducing the hydrolysis of silanes caused by excessive acidity or alkalinity of the product, thereby shortening the storage period. Preferably, component II is triethylamine.

[0056] Component III, polyetheramine, is an aliphatic primary amine-modified polypropylene glycol with an average molar mass of 200-2000 Daltons. Specific commercial products can be selected from Huntsman's Jeffamine D-230 (bifunctional), Jeffamine D-400 (bifunctional), and Jeffamine T-403.

[0057] The ratio of the primary amino equivalent in component III to the C=C double bond equivalent in component I is 1:1.2 to 1.2:1, preferably 1:1.1 to 1.1:1, and more preferably 1.05:1.

[0058] Component IV is a silane coupling agent containing a secondary amine group. The silane coupling agent may be selected from siloxanes with an epoxy group, such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, and γ-glycidoxypropyltriethoxysilane.

[0059] As another embodiment, the silane coupling agent may be a siloxane with an isocyanate group, such as 3-isocyanate propyltrimethoxysilane, 3-isocyanate propyltriethoxysilane, or 3-isocyanate propylmethyldimethoxysilane.

[0060] The ratio of the equivalent of the secondary amine group in component IV to the equivalent of the primary amine group in component III is 1:1.2 to 1.2:1, preferably 1:1.1 to 1.1:1, and more preferably 1.05:1.

[0061] Furthermore, the preparation method of the silane-modified polyether containing phosphate ester of the above component A3 is as follows: S1: Add component I to a dry and clean reactor, set the stirring speed to 50-200 r / m, control the temperature to 20-40℃, add component II dropwise to the reactor within 10-30 minutes and adjust the pH to 6-8, and collect the product; S2: Under continuous nitrogen purging, load the reaction product of S1 into a dry and clean reactor, add the reaction product of S1 dropwise into the reactor, control the dropwise addition time to be 30-90 minutes, control the internal temperature to be 20-40℃ throughout the process, after the dropwise addition is completed, control the temperature to be raised to 50-80℃ and continue the reaction for 4-8 hours, then remove water vapor and residual small molecules by vacuuming to obtain the reaction product. S3: Cool down to 20-50℃, add component IV dropwise to the reactor within 30-90 minutes, and after the addition is complete, heat up to 60-90℃ and react for 1-4 hours to obtain a silane-modified polyether product containing phosphate ester.

[0062] The silane-modified polyether containing phosphate esters in component A3 accounts for 1-15% of the total weight of the modified silicone, preferably 3-12%, and more preferably 5-10%.

[0063] Component A4, the reactive plasticizer, refers to a single-terminated silane compound with hydrolytic reactivity. It can be selected from alkylsilanes containing 6-30 carbon atoms, such as octyltrimethoxysilane, isooctyltrimethoxysilane, dodecyltrimethoxysilane, hexadecyltrimethoxysilane, and octadecyltrimethoxysilane.

[0064] Component A4 can also be selected from mono-terminated siloxane-modified polymers, such as mono-terminated siloxane-modified polyethers, purchased from Wacker Chemie Geniosil XM25.

[0065] The component A4 active plasticizer accounts for 1-20% of the total weight of the modified silicone, preferably 3-16%, and more preferably 5-12%.

[0066] Component A5, the dehydrating agent, is a substance that preferentially reacts with water, thereby improving the stability of the adhesive. It is usually selected from siloxanes, such as vinyltrimethoxysilane, vinyltriethoxysilane, methyltrimethoxysilane, and methacryloxypropyltrimethoxysilane.

[0067] Component A5 can also be selected from monoisocyanate compounds, such as p-toluenesulfonyl isocyanate, purchased from Borchers Additive TI in Germany.

[0068] Component A5 can also be selected from low molecular weight active oxazolidine compounds, such as incozol 2, purchased from incozol.

[0069] The component A5, the dehydrating agent, accounts for 0.5-4% of the total weight of the modified silica gel, preferably 0.8-3%, and more preferably 1-2%.

[0070] The A6 adhesion promoter is a type of siloxane coupling agent containing a functional group. When the functional group is mercapto, it can be selected from mercaptotrimethoxysilane or mercaptotriethoxysilane; when the functional group is epoxy, it can be selected from γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, or γ-glycidoxypropyltriethoxysilane; when the functional group is amino, it can be selected from aminopropyltrimethoxysilane, aminopropyltriethoxysilane, or N-(2-aminoethyl)-3-aminopropyltrimethoxysilane.

[0071] The component A6 adhesion promoter accounts for 0.5-6% of the total weight of the modified silicone, preferably 1-4%, and more preferably 2-3%.

[0072] The A7 filler can be selected from mineral fillers such as silica powder, wollastonite, and calcium carbonate. Preferably, the filler is calcium carbonate. More preferably, the calcium carbonate has undergone surface treatment or coating. The treatment or coating agent can be selected from fatty acids, titanate coupling agents, or silane coupling agents.

[0073] It is expected that the hydrophobicity of calcium carbonate powder will be greatly improved after its surface is modified with fatty acid, titanate coupling agent or silane coupling agent, preferably with a BET surface area ≥ 50 m². 2 / g, the large specific surface area allows the powder to fully contact the silicone resin and produce physical or chemical reactions, thereby enhancing the strength of the adhesive.

[0074] As one example, component A7 can be selected from Provencale's Mikhart 1T.

[0075] The A7 filler component accounts for 5%-75% of the total weight of the modified silane adhesive, preferably 15-65%, and more preferably 25-55%.

[0076] Component A8 is a thixotropic agent that can be used to adjust the rheological properties of adhesives. Preferably, the thixotropic agent is fumed silica, which can be selected from Cabot TS-720, Evonik AEROSIL R 974, AEROSIL R202, and Wacker HDKH15.

[0077] The component A8 thixotropic agent accounts for 0.5-8% of the total weight of the modified silica gel.

[0078] The catalyst A9 mentioned above refers to a class of catalysts that can catalyze the hydrolysis and polycondensation of siloxanes. These catalysts can be selected from organic acid derivatives of metallic tin, titanium, zinc, bismuth, and zirconium, including organotin compounds such as dibutyltin dilaurate, dibutyltin oxide, tin isooctanoate, and dibutyltin acetylacetone (U-220H), and organotitanium compounds such as tetrapropyl titanate, tetraisopropyl titanate, tetraisobutyl titanate, and ethyl acetoacetate titanium complex (brand name TYZOR 726). These catalysts can also be selected from tertiary amine compounds or nitrogen-containing heterocyclic compounds, such as triethylamine, N,N-dimethylcyclohexylamine, N-methylimidazole, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and 1,5-diazabicyclo[4.3.0]non-5-ene.

[0079] Preferably, component A9 is selected from dibutyltin dilaurate and dibutyltin acetylacetone.

[0080] The A9 catalyst component accounts for 0.01%-1% of the total weight of the modified silica gel.

[0081] Other additives in component A10 refer to light stabilizers and antioxidants, preferably one or a mixture of two of 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole (UV327) and bis(2,2,6,6-tetramethylpiperidinyl) sebacate (UV770).

[0082] The components A10 light stabilizer and antioxidant account for 0.2%-2% of the total weight of the modified silicone.

[0083] A method for preparing the above-mentioned high-strength modified silane adhesive is further provided, comprising the following steps: S1: At room temperature, add components A1, A2, A3, A4, A5 and component A10 to a dry and clean double planetary mixer, set the speed to 200 r / m, and stir for 10-30 minutes until a homogeneous mixture is formed. S2: Add components A7 and A8 to the mixer, increase the rotation speed to 2000 r / m, and set the vacuum degree to -0.095Mpa. Disperse rapidly in a vacuum environment for 30-60 minutes. S3: Add components A6 and A9 to the mixer, set the speed to 500 rpm, and continue stirring for 10-30 minutes. Open the vacuum valve, set the vacuum level to (-0.075) - (-0.095) MPa, and stir at 10-100 rpm for 30-60 minutes to remove bubbles.

[0084] The abbreviations and basic parameters of some raw materials and reagents in this invention are as follows: GENIOSIL STP-E15: Trimethoxysilane-terminated polypropylene glycol, Wacker Chemie SPUR+1050MM: Trimethoxysilane-modified polyurethane at both ends, Momentive New Materials SILIKOPHENAC 1000: A liquid methoxy-functionalized silicone resin, Evonik Industries DOWSIL 3074: A liquid methoxy-functionalized silicone resin, Dow Chemical Sipomer PAM-4000: Ethyl methacrylate, Solvay Jeffamine D-230: A bifunctional polyetheramine with a primary amine equivalent of approximately 120 g / mol, produced by Huntsman. CG-560: γ-glycidyl etheroxypropyltrimethoxysilane, Jiangxi Chenguang New Materials KH-901: 3-Propyl isocyanate trimethoxysilane, Hangzhou Jessica Chemical Co., Ltd. Phosphate-containing silane-modified polyether E1: Homemade Phosphate-containing silane-modified polyether E2: Homemade KH-1631: Hexadecyltrimethoxysilane, Hangzhou Jessica Chemical Co., Ltd. Geniosil XM25: Trimethoxy-terminated polypropylene glycol, average molar mass = 5000 g / mol, Wacker Chemie. HexamollDINCH: Diisononyl cyclohexane-1,2-dicarboxylate, BASF CG-171: Vinyltrimethoxysilane, dehydrating agent, Jiangxi Chenguang New Materials CG-540: Aminopropyltrimethoxysilane, adhesion promoter, Jiangxi Chenguang New Materials Mikhart 1T: Nano Calcium Carbonate, Provencale TS-720: Fumed silica, Cabot UH-220: Dibutyltin acetylacetone, Nitto Chemical Co., Ltd. UV-327: Ultraviolet light absorber, BASF UV-770: Ultraviolet light stabilizer, BASF The preparation of silane-modified polyether E1 containing phosphate esters is as follows: S1: Add 22.81g SipomerPAM-4000 (approximately 0.1mol) to a dry and clean reaction vessel, set the stirring speed to 150 r / m, control the temperature at 30℃, add 12.2g triethylamine dropwise to the reaction vessel within 20 minutes and adjust the pH to 7.3, then collect the product; S2: Under continuous nitrogen purging, 12.6g JeffamineD-230 (approximately 0.105mol primary amine) was loaded into a dry and clean reactor. The reaction product of S1 was added dropwise to the reactor over a period of 60 minutes. The internal temperature was maintained at 30℃ throughout the process. After the addition was completed, the temperature was raised to 65℃ and the reaction was continued for 7 hours. Vacuum was then applied to remove water vapor and residual small molecules, yielding a light yellow product. S3: Cool down to 30℃, and add 24.82g of CG-560 (about 0.105mol) dropwise to the reactor within 60 minutes. After the addition is complete, heat up to 80℃ and react for 3 hours until the epoxy equivalent drops to 0. Stop the reaction and collect the product to obtain a light yellow silane-modified polyether product E1 containing phosphate ester.

[0085] The preparation of silane-modified polyether E2 containing phosphate esters is as follows: S1: Add 22.81g Sipomer PAM-4000 (approximately 0.1mol) to a dry and clean reaction vessel, set the stirring speed to 150 r / m, control the temperature at 30℃, add 12.2g triethylamine dropwise to the reaction vessel within 20 minutes and adjust the pH to 7.3, then collect the product; S2: Under continuous nitrogen purging, 12.6g JeffamineD-230 (approximately 0.105mol primary amine) was loaded into a dry and clean reactor. The reaction product of S1 was added dropwise to the reactor over a period of 60 minutes. The internal temperature was maintained at 30℃ throughout the process. After the addition was completed, the temperature was raised to 65℃ and the reaction was continued for 7 hours. Vacuum was then applied to remove water vapor and residual small molecules, yielding a light yellow product. S3: Cool down to 30℃, and add 21.55g KH-901 (about 0.105mol) dropwise to the reactor within 60 minutes. After the addition is complete, heat up to 70℃ and react for 1.5 hours until the NCO value drops to 0%. Stop the reaction and collect the product to obtain a light yellow silane-modified polyether product E2 containing phosphate ester.

[0086] Example 1 A method for preparing a high-strength modified silane adhesive for bonding metal substrates includes the following steps: S1: At room temperature, add components A1, A2, A3, A4, A5 and component A10 to a dry and clean double planetary mixer, set the speed to 200 r / m, and stir for 20 minutes until a homogeneous mixture is formed. S2: Add components A7 and A8 (both pre-dehydrated under vacuum for 24 hours) to the mixer, increase the rotation speed to 2000 r / m, and set the vacuum degree to -0.095 MPa. Disperse rapidly under vacuum for 45 minutes. S3: Add components A6 and A9 to the mixer, set the speed to 500 r / m, and continue stirring for 20 minutes. Open the vacuum valve, set the vacuum level to -0.085 MPa, and stir at 10-100 r / m for 60 minutes to remove bubbles.

[0087] Examples 2-9 The preparation process is the same as in Example 1. The amount of different components added in each example is shown in Table 1 and Table 2.

[0088] Comparative Examples 1-3 The preparation process is the same as in Example 1, and the different amounts of components added in each comparative example are shown in Table 2.

[0089] Table 1 Table 2 Performance testing (1) Tensile shear strength: The test was conducted in accordance with GB / T 7124-2023 standard. Two sets of test substrates were used: one set was aluminum plate bonded to aluminum plate, and the other set was steel plate bonded to steel plate. The tensile shear strength of the two sets of substrates was tested after 24 hours of curing and after 168 hours of curing. Each set of test was conducted 3 times, and the average value was recorded.

[0090] (2) Hardness: The hardness of modified silicone after 7 days of wet curing under standard conditions (temperature 23±2℃, humidity 50±10%) was determined according to GB / T 531.1-2008 "Test method for indentation hardness of vulcanized rubber or thermoplastic rubber Part 1: Shore hardness test (Shore hardness)". Five points were taken for testing for each sample and the average value was taken.

[0091] (3) 85% retention rate: After 500 hours of continuous aging at 85±2℃ and 85±5% humidity, the tensile shear strength was tested according to the test method in (1). The strength retention rate = (strength after aging / initial strength) × 100%.

[0092] The specific test results are summarized in Table 3 below: Table 3 As shown in Table 3, the modified silicone of this invention exhibits excellent tensile shear strength (≥4 MPa) and hardness (Shore D35-60) when bonded to both aluminum and steel substrates, with a double 85 retention rate exceeding 90%. In contrast, Comparative Example 1, lacking component A2, only achieved a Shore D10 hardness and a tensile shear strength ≤2 MPa, exhibiting 100% cohesive failure (CF) due to insufficient cross-linking of the adhesive caused by the absence of reinforcing silicone, resulting in low cohesive strength. Comparative Example 2, while possessing excellent hardness (Shore D50), also showed a tensile shear strength ≤2.5 MPa on a metal substrate, exhibiting 100% adhesive failure (AF) (i.e., interfacial fracture between the adhesive and substrate). This was due to the absence of the phosphate-containing silane-modified polyether adhesion promoter of this invention, resulting in relatively weak adhesion between the adhesive and the metal substrate, leading to interfacial fracture under external tensile force. Comparative Example 3 used conventional plasticizers, and its performance retention rate was only 75% after the double 85 test. This was due to the performance decline caused by the migration of traditional plasticizers under high temperature and high humidity conditions.

[0093] In summary, the high-strength modified silane adhesive of the present invention is a single-component product that does not require pre-coating. After water vapor curing, the product exhibits excellent tensile and shear strength, making it particularly suitable for bonding or sealing metal substrates with high adhesion strength requirements, and thus has high market application value.

[0094] Specifically, the high-strength modified silane adhesive of the present invention has the following advantages: Excellent adhesion: This invention introduces silane-modified polyether containing phosphate esters, whose phosphate groups can chemically bond with hydroxyl groups on the metal surface to form covalent bonds, greatly improving the adhesion of silicone to metal substrates. Compared with existing technologies that rely on conventional coupling agents, this invention can achieve a tensile shear strength of ≥4 MPa without the need for a primer.

[0095] Excellent compatibility: Compared with common phosphate ester adhesion promoters such as epoxy phosphate esters and polyester phosphate esters, the phosphate ester-containing silane-modified polyether of the present invention has excellent compatibility with silicone systems, and can participate in cross-linking reactions through silane oxygen groups to avoid the migration of additives.

[0096] Significant cohesive strength: By introducing multifunctional reinforcing silicone resin (especially POSS), a three-dimensional network structure with high cross-linking density is formed, enabling the colloidal hardness to reach Shore D35 or higher, far exceeding the Shore A hardness level of conventional MS adhesive.

[0097] Excellent durability: The use of reactive plasticizers instead of traditional non-reactive plasticizers avoids the performance degradation caused by plasticizer migration. After the double 85 aging test, the strength retention rate is ≥90%, which is significantly better than the comparative example (75%) using inert plasticizers.

[0098] Ease of application: This invention is a single-component solvent-free product that does not require pre-coating, making it easy to apply, healthy and environmentally friendly, avoiding the cumbersome traditional primer process and the health risks associated with solvent-based additives.

[0099] Excellent overall performance: The modified silane adhesive of this invention has a tensile shear strength of 4.1-5.7 MPa and a Shore D hardness of 35-55 after curing. It has the characteristics of both high strength and high hardness, and is particularly suitable for fields with high requirements for bonding strength, such as rail transportation, automobiles and ships, container manufacturing, and electronic equipment.

[0100] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A high-strength modified silane adhesive for bonding metal substrates, characterized in that, The components include the following parts by weight: Component A1: 20-60 parts of silane-modified polymer base resin; Component A2: 2-30 parts of reinforcing silicone resin; Component A3: 1-15 parts of a phosphate-modified silane compound; Component A4: 1-20 parts of active plasticizer; Component A5: 0.5-4 parts of dehydrating agent; Component A6: Adhesion promoter 0.5-6 parts; Component A7: 5-75 parts of filler; Component A8: 0.5-8 parts of thixotropic agent; Component A9: 0.01-1 part catalyst; The molecular chain of the phosphate-containing modified silane compound contains both phosphate groups and hydrolyzable silane groups.

2. The high-strength modified silane adhesive for bonding metal substrates according to claim 1, characterized in that, It consists of the following components by weight percentage: Component A1: 20-60% silane-modified polymer base resin; Component A2: 2-30% reinforcing silicone resin; Component A3: 1-15% of phosphate-modified silane compounds; Component A4: 1-20% reactive plasticizer; Component A5: Dehydrating agent 0.5-4%; Component A6: Adhesion promoter 0.5-6%; Component A7: 5-75% filler; Component A8: Thixotropic agent 0.5-8%; Component A9: Catalyst 0.01-1%; Component A10: 0.2-2% other additives.

3. The high-strength modified silane adhesive for bonding metal substrates according to claim 1, characterized in that, The phosphate-containing modified silane compound is a phosphate-containing silane-modified polyether, prepared by reacting the following raw materials: Component I: Alkenyl phosphate ester; Component II: Tertiary amine; Component III: Polyetheramine; the ratio of the primary amino equivalent in the polyetheramine to the C=C double bond equivalent in Component I is 1:1.2 to 1.2:1; Component IV: Reactive silane coupling agent; the ratio of the equivalent of the group that can react with the secondary amine group in the reactive silane coupling agent to the equivalent of the primary amine group in Component III is 1:1.2 to 1.2:

1.

4. The high-strength modified silane adhesive for bonding metal substrates according to claim 3, characterized in that, Component I is the reaction product of hydroxyethyl methacrylate and phosphate ester, or the reaction product of ethoxylated / propoxylated hydroxyethyl methacrylate and phosphate ester; Component II is triethylamine; Component III is an aliphatic primary amine modified polypropylene glycol with an average molar mass of 200-2000 Daltons. Component IV is an epoxy-containing silane coupling agent or an isocyanate-containing silane coupling agent.

5. The high-strength modified silane adhesive for bonding metal substrates according to claim 1, characterized in that, The component A1 is a polymer with at least two alkoxysilyl groups at both ends, and the polymer is a polyether, polyester, polycarbonate, polyurethane, polyacrylate, polybutadiene, polypentadiene, or epoxy resin.

6. The high-strength modified silane adhesive for bonding metal substrates according to claim 1, characterized in that, Component A2 is a polyhedral polysilsesquioxane resin with an alkoxy content of 1-50 wt%. The polyhedral polysilsesquioxane resin is one or more of a methoxy-containing methyl silicone resin, a methoxy-containing methylphenyl silicone resin, or a methoxy-containing phenyl silicone resin.

7. The high-strength modified silane adhesive for bonding metal substrates according to claim 1, characterized in that, Component A4 is a single-terminal silane compound or a single-terminal siloxane modified polymer with hydrolytic reactivity.

8. The high-strength modified silane adhesive for bonding metal substrates according to claim 1, characterized in that, Includes at least one of the following technical features: Component A5 is one or more of siloxane compounds, monoisocyanate compounds, or oxazolidine compounds; Component A6 is a silane coupling agent containing functional groups, wherein the functional groups are mercapto, epoxy, or amino. The component A7 is calcium carbonate whose surface has been treated with fatty acid, titanate coupling agent or silane coupling agent; The component A8 is fumed silica; The component A9 is an organotin compound, an organotitanium compound, a tertiary amine compound, or a nitrogen-containing heterocyclic compound; The component A10 is a light stabilizer and an antioxidant.

9. A method for preparing a high-strength modified silane adhesive for bonding metal substrates as described in any one of claims 1-8, characterized in that, Includes the following steps: S1: Mix components A1, A2, A3, A4, A5 and component A10 evenly to obtain the first mixture; S2: Add component A7 and component A8 to the first mixture and disperse under vacuum to obtain a second mixture; S3: Add component A6 and component A9 to the second mixture, mix evenly, and then degas under vacuum conditions to obtain the high-strength modified silane adhesive.

10. Claim 1 The application of the high-strength modified silane adhesive for bonding metal substrates as described in any one of the 8 claims in the bonding of metal substrates.

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