Impact-resistant hinge joint repairing epoxy structural adhesive and preparation method thereof

Abstract

The invention relates to an anti-impact hinge joint repairing epoxy structural adhesive and a preparation method thereof, and belongs to the technical field of structural adhesives. According to the structural adhesive disclosed by the invention, polysiloxane epoxy resin and silane polyimide are introduced into a basic formula, so that a dual-crosslinking structure is formed, the mechanical strength and toughness of the structural adhesive are enhanced, meanwhile, a preparation method of silane polyimide is optimized, and the stability of substances is improved; besides, organic montmorillonite and silanized carbon nanotubes are added as fillers, a line-plane structure arrangement form is formed in a system, the orientation of the carbon nanotubes can be effectively changed to achieve a dispersion effect, the toughness and strength are greatly improved, and the structural adhesive has excellent impact resistance and no sagging phenomenon, and meets the requirements of plate girder bridge hinge joint repair.

Description

An impact-resistant epoxy structural adhesive for repairing hinge joints and its preparation method Technical Field

[0001] This invention belongs to the field of structural adhesive technology, and relates to an impact-resistant epoxy structural adhesive for repairing hinge joints and its preparation method. Background Technology

[0002] In my country's highway bridge construction, prefabricated hinged slab beam structures are widely used. These slab beams are connected by cast-in-place concrete hinges. However, the repeated misalignment of the slab beams on both sides of the hinges due to heavy vehicle traffic accelerates their deterioration. Traditional methods for repairing hinge damage, such as chiseling and rebuilding, pasting steel plates, and adding shear reinforcement, have drawbacks including long construction periods, complex processes, and significant traffic disruption. In recent years, a chemical grouting method for reinforcing hinges—beam bottom grouting—has emerged. This method allows for the injection of repair materials (mainly epoxy-based repair adhesives) into the hinge gaps and between the beam slabs using specialized equipment, restoring the bond between the concrete on both sides, without affecting traffic flow above. However, commonly used E-44 and E-51 epoxy resins are prone to sagging due to temperature variations, which severely affects the reinforcement effect and leads to material waste. High molecular weight polymers are usually introduced as thickeners to achieve a certain degree of thickening, but the system concentration is high, the reaction rate between the curing agent and the resin is too fast, and the curing time is short, which is not conducive to construction. In addition, the addition of nanofillers can improve the stiffness and consistency of the system, but it can easily increase the brittleness of the epoxy resin. When the structural adhesive is used as an interface agent, it can easily cause the hinge joint to fail under high stress, leading to reinforcement failure.

[0003] Carbon nanotubes possess excellent mechanical strength and, as nanofillers, can significantly improve the tensile strength, fracture toughness, and impact resistance of structural adhesives. However, in practical applications, the orientation of carbon nanotubes in the resin severely affects their effectiveness in improving material properties. Excessive addition of carbon nanotubes can cause them to entangle and agglomerate into bundles in viscous systems, making them difficult to wet with resin, forming weak interfaces, leading to stress concentration and interface detachment, which in turn reduces mechanical strength. Therefore, based on the above, this invention provides an impact-resistant epoxy structural adhesive for repairing hinge joints and its preparation method, making further optimizations based on existing technologies. Summary of the Invention

[0004] This invention relates to an impact-resistant epoxy structural adhesive for repairing hinge joints and its preparation method, belonging to the field of structural adhesive technology. The structural adhesive of this invention introduces polysiloxane epoxy resin and silane polyimide into its basic formulation, forming a double cross-linked structure that enhances the mechanical strength and toughness of the adhesive. Simultaneously, the preparation method of silane polyimide is optimized to improve the stability of the material. Furthermore, the addition of organomontmorillonite and silanized carbon nanotubes as fillers forms a line-to-surface structure arrangement in the system, effectively altering the orientation of the carbon nanotubes to achieve a dispersion effect and significantly improving toughness and strength. This structural adhesive exhibits excellent impact resistance, exhibits no sagging, and meets the requirements for hinge joint repair in slab-beam bridges.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] An impact-resistant epoxy structural adhesive for repairing hinge joints, comprising component A and component B, wherein component A comprises the following raw materials in parts by weight: 50-60 parts of bisphenol A type epoxy resin, 50-70 parts of polysiloxane epoxy resin, 30-50 parts of filler, 8-12 parts of diluent, 0.1-0.3 parts of defoamer, and 1-3 parts of coupling agent; and component B comprises the following raw materials in parts by weight: 40-60 parts of curing agent, 40-50 parts of siloxane polyimide, 2-5 parts of catalyst, and 0.1-0.3 parts of defoamer.

[0007] Furthermore, the filler is composed of silanized carbon nanotubes and organomontmorillonite in a mass ratio of 3-5:0.5-1, wherein the diameter and aspect ratio of the silanized carbon nanotubes are 0.8-2 nm and 2-4:1, respectively, and the thickness of the organomontmorillonite is 1-2 nm.

[0008] Furthermore, the preparation method of the siloxane polyimide includes the following steps:

[0009] (1) Heat tetrahydrofuran in a distillation apparatus while passing nitrogen gas through it. After the distillate is mixed with benzophenone and sodium to form a dark blue liquid, put the distillate into a dry reaction apparatus that is passed nitrogen gas through it.

[0010] (2) Add polyimide to the reaction apparatus and place it in an ice bath. Then add γ-aminopropyltriethoxysilane and stir to mix. Then heat up, add catalyst and dehydrating agent, mix and keep warm. After cooling to room temperature, wash with petroleum ether and put into a vacuum drying oven to dry to obtain siloxane polyimide.

[0011] Further, the heating temperature in step (1) is 68-72℃, the mass ratio of the distillate to benzophenone and sodium is 10:0.2-0.5:0.3, and the mass ratio of the distillate to polyimide, γ-aminopropyltriethoxysilane, catalyst and dehydrating agent in step (2) is 5-7:1.5-2:3:0.1-0.2:1-1.5, wherein the catalyst is acetic anhydride-pyridine and the dehydrating agent is isoquinoline.

[0012] Further, in step (2), the mixing temperature and time are -1~0℃ and 2h respectively, the heating refers to heating to 40-50℃, the heat preservation time is 8-10h, and the drying temperature and time are 55-60℃ and 3-5h respectively.

[0013] Furthermore, the polysiloxane epoxy resin is a branched polysiloxane epoxy resin, and the molecular weight of the branched polysiloxane epoxy resin is 1000-2000.

[0014] Furthermore, the diluent is benzyl alcohol, the defoamer is BYK-019, the coupling agent is KH560, the catalyst is stannous octoate, and the curing agent is an aromatic amine curing agent.

[0015] Furthermore, the preparation method of the impact-resistant hinge joint repair epoxy structural adhesive is as follows: component A raw material is stirred at high speed according to the weight parts to obtain viscous component A, and component B raw material is stirred at low speed according to the weight parts to obtain viscous component B. Then, viscous component A and viscous component B are mixed at a mass ratio of 1.5-2:1, and the mixture is degassed under vacuum to obtain the impact-resistant hinge joint repair epoxy structural adhesive. The high speed and time are 1000-1200 r / min and 3-5 min, respectively, and the low speed and time of component B are 400-500 r / min and 3-5 min, respectively.

[0016] The beneficial effects of this invention are:

[0017] 1. The structural adhesive of the present invention introduces polysiloxane epoxy resin and silane polyimide into the basic formulation to form a double cross-linked structure, which strengthens the mechanical strength and toughness of the structural adhesive. At the same time, the addition of a solvent pretreatment step ensures that there is no water reaction during the preparation of silane polyimide, prevents hydrolysis of silane coupling agent, and thus improves the stability of the substance.

[0018] 2. Furthermore, by adding organomontmorillonite and silanized carbon nanotubes as fillers, their size is smaller than that of the epoxy resin molecular chains. They are intercalated into the molecular chains and form a pinning effect. The sheet-like structure of organomontmorillonite acts as a fulcrum, preventing crack propagation and improving toughness, while silanized carbon nanotubes act as a skeletal support, facilitating stress transfer and improving system strength. The modified fillers are uniformly dispersed in the epoxy resin system. The sheet-like organomontmorillonite can intercalate between the silanized carbon nanotubes. By adjusting the ratio and size of the two, a line-to-surface structure is formed in the system, which can effectively change the orientation of carbon nanotubes to achieve a dispersion effect, greatly improving toughness and strength. This structural adhesive has excellent impact resistance and no sagging, meeting the requirements for hinge joint repair of slab-beam bridges. Detailed Implementation

[0019] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features and effects of the present invention, in conjunction with embodiments, is provided below.

[0020] The bisphenol A type epoxy resin involved in this invention is epoxy resin E44; the polyimide is soluble polyimide, purchased from Kaiming Plastics (Dongguan) Co., Ltd., brand name SP-1; the organomontmorillonite was purchased from Zhejiang Fenghong New Material Co., Ltd., with a mesh size of 1000; the acetic anhydride-pyridine is composed of acetic anhydride and pyridine in a mass ratio of 1:1; the aromatic amine curing agent was purchased from Jiangsu Haolong Chemical Co., Ltd., model name LS-113.

[0021] Example 1

[0022] An impact-resistant epoxy structural adhesive for repairing hinge joints, comprising component A and component B, wherein component A comprises the following raw materials in parts by weight: 50 parts of bisphenol A type epoxy resin, 50 parts of polysiloxane epoxy resin, 30 parts of filler, 8 parts of diluent, 0.1 parts of defoamer, and 1 part of coupling agent; and component B comprises the following raw materials in parts by weight: 40 parts of curing agent, 40 parts of siloxane polyimide, 2 parts of catalyst, and 0.1 parts of defoamer.

[0023] The filler is composed of silanized carbon nanotubes and organomontmorillonite in a mass ratio of 3:0.5. The diameter and aspect ratio of the silanized carbon nanotubes are 0.8 nm and 2:1, respectively, and the thickness of the organomontmorillonite is 1 nm.

[0024] The preparation method of the siloxane polyimide includes the following steps:

[0025] (1) Heat tetrahydrofuran in a distillation apparatus while passing nitrogen gas through it. After the distillate is mixed with benzophenone and sodium to form a dark blue liquid, put the distillate into a dry reaction apparatus that is passed nitrogen gas through it.

[0026] (2) Add polyimide to the reaction apparatus and place it in an ice bath. Then add γ-aminopropyltriethoxysilane and stir to mix. Then heat up, add catalyst and dehydrating agent, mix and keep warm. After cooling to room temperature, wash with petroleum ether and put into a vacuum drying oven to dry to obtain siloxane polyimide.

[0027] The heating temperature in step (1) is 68°C, the mass ratio of the distillate to benzophenone and sodium is 10:0.2:0.3, and the mass ratio of the distillate to polyimide, γ-aminopropyltriethoxysilane, catalyst and dehydrating agent in step (2) is 5:1.5:3:0.1:1, wherein the catalyst is acetic anhydride-pyridine and the dehydrating agent is isoquinoline.

[0028] The mixing temperature and time in step (2) are -1℃ and 2h, respectively. The heating refers to heating to 40℃. The heat preservation time is 8h. The drying temperature and time are 55℃ and 3h, respectively.

[0029] The polysiloxane epoxy resin is a branched polysiloxane epoxy resin, and the molecular weight of the branched polysiloxane epoxy resin is 1000.

[0030] The diluent is benzyl alcohol, the defoamer is BYK-019, the coupling agent is KH560, the catalyst is stannous octoate, and the curing agent is an aromatic amine curing agent.

[0031] The preparation method of the impact-resistant hinge joint repair epoxy structural adhesive is as follows: Component A raw material is stirred at high speed according to the weight parts to obtain a viscous component A, and component B raw material is stirred at low speed according to the weight parts to obtain a viscous component B. Then, the viscous component A and viscous component B are mixed at a mass ratio of 1.5:1, and the mixture is degassed under vacuum to obtain the impact-resistant hinge joint repair epoxy structural adhesive. The high-speed stirring speed and time are 1000 r / min and 3 min, respectively, and the low-speed stirring speed and time of component B are 400 r / min and 3 min, respectively.

[0032] The preparation method of the polysiloxane epoxy resin includes the following steps:

[0033] A1: 3-glycidyl etheroxypropyltrimethoxysilane, diphenyl cinnamoethylene glycol and barium hydroxide were mixed and stirred in a mass ratio of 20:27:0.1 under nitrogen gas. The mixture was then heated to 80°C and kept at that temperature for 6 hours. After the gas was removed, the mixture was dried in a vacuum at 60°C for 4 hours to obtain a viscous liquid.

[0034] A2: Mix E-51 bisphenol A type epoxy resin, viscous liquid, and curing agent in a mass ratio of 4:1:3.8, heat to 60℃ and stir for 30 minutes, then cool to room temperature to obtain polysiloxane epoxy resin.

[0035] The curing agent in step A2 is prepared by heating and stirring methylhexahydrophthalic anhydride and tetraethylammonium bromide at a mass ratio of 50:1 at 60°C for 30 minutes.

[0036] The method for preparing the silanized carbon nanotubes is as follows: carbon nanotubes are oxidized in a mixed acid, then stirred in a silane coupling agent solution, and dried to obtain silanized carbon nanotubes. The mass ratio of the carbon nanotubes, the mixed acid, and the silane coupling agent solution is 1:3:4, wherein the mixed acid is composed of concentrated nitric acid and concentrated nitric acid in a mass ratio of 3:1, and the silane coupling agent solution is a 2 mmol / L γ-aminopropyltriethoxysilane ethanol solution.

[0037] Example 2

[0038] An impact-resistant epoxy structural adhesive for repairing hinge joints, comprising component A and component B, wherein component A comprises the following raw materials in parts by weight: 55 parts of bisphenol A type epoxy resin, 60 parts of polysiloxane epoxy resin, 40 parts of filler, 10 parts of diluent, 0.2 parts of defoamer, and 2 parts of coupling agent; and component B comprises the following raw materials in parts by weight: 50 parts of curing agent, 45 parts of siloxane polyimide, 3.5 parts of catalyst, and 0.2 parts of defoamer.

[0039] The filler is composed of silanized carbon nanotubes and organomontmorillonite in a mass ratio of 4:0.7. The diameter and aspect ratio of the silanized carbon nanotubes are 1.5 nm and 3:1, respectively, and the thickness of the organomontmorillonite is 1.5 nm.

[0040] The preparation method of the siloxane polyimide includes the following steps:

[0041] (1) Heat tetrahydrofuran in a distillation apparatus while passing nitrogen gas through it. After the distillate is mixed with benzophenone and sodium to form a dark blue liquid, put the distillate into a dry reaction apparatus that is passed nitrogen gas through it.

[0042] (2) Add polyimide to the reaction apparatus and place it in an ice bath. Then add γ-aminopropyltriethoxysilane and stir to mix. Then heat up, add catalyst and dehydrating agent, mix and keep warm. After cooling to room temperature, wash with petroleum ether and put into a vacuum drying oven to dry to obtain siloxane polyimide.

[0043] The heating temperature in step (1) is 70°C, the mass ratio of the distillate to benzophenone and sodium is 10:0.35:0.3, and the mass ratio of the distillate to polyimide, γ-aminopropyltriethoxysilane, catalyst and dehydrating agent in step (2) is 6:1.8:3:0.15:1.25, wherein the catalyst is acetic anhydride-pyridine and the dehydrating agent is isoquinoline.

[0044] In step (2), the mixing temperature and time are -0.5℃ and 2h, respectively. The heating refers to heating to 45℃. The heat preservation time is 9h. The drying temperature and time are 58℃ and 4h, respectively.

[0045] The polysiloxane epoxy resin is a branched polysiloxane epoxy resin, and the molecular weight of the branched polysiloxane epoxy resin is 1500.

[0046] The diluent is benzyl alcohol, the defoamer is BYK-019, the coupling agent is KH560, the catalyst is stannous octoate, and the curing agent is an aromatic amine curing agent.

[0047] The preparation method of the impact-resistant hinge joint repair epoxy structural adhesive is as follows: Component A raw material is stirred at high speed according to the weight parts to obtain a viscous component A, and component B raw material is stirred at low speed according to the weight parts to obtain a viscous component B. Then, the viscous component A and viscous component B are mixed at a mass ratio of 1.8:1, and the mixture is degassed under vacuum to obtain the impact-resistant hinge joint repair epoxy structural adhesive. The high-speed stirring speed and time are 1100 r / min and 4 min, respectively, and the low-speed stirring speed and time of component B are 450 r / min and 4 min, respectively.

[0048] The preparation method of the polysiloxane epoxy resin includes the following steps:

[0049] A1: 3-glycidyl etheroxypropyltrimethoxysilane, diphenyl cinnamoethylene glycol and barium hydroxide were mixed and stirred in a mass ratio of 20:27:0.1 under nitrogen gas. The mixture was then heated to 80°C and kept at that temperature for 6 hours. After the gas was removed, the mixture was dried in a vacuum at 60°C for 4 hours to obtain a viscous liquid.

[0050] A2: Mix E-51 bisphenol A type epoxy resin, viscous liquid, and curing agent in a mass ratio of 4:1:3.8, heat to 60℃ and stir for 30 minutes, then cool to room temperature to obtain polysiloxane epoxy resin.

[0051] The curing agent in step A2 is prepared by heating and stirring methylhexahydrophthalic anhydride and tetraethylammonium bromide at a mass ratio of 50:1 at 60°C for 30 minutes.

[0052] The method for preparing the silanized carbon nanotubes is as follows: carbon nanotubes are oxidized in a mixed acid, then stirred in a silane coupling agent solution, and dried to obtain silanized carbon nanotubes. The mass ratio of the carbon nanotubes, the mixed acid, and the silane coupling agent solution is 1:3:4, wherein the mixed acid is composed of concentrated nitric acid and concentrated nitric acid in a mass ratio of 3:1, and the silane coupling agent solution is a 2 mmol / L γ-aminopropyltriethoxysilane ethanol solution.

[0053] Example 3

[0054] An impact-resistant epoxy structural adhesive for repairing hinge joints, comprising component A and component B, wherein component A comprises the following raw materials in parts by weight: 60 parts of bisphenol A type epoxy resin, 70 parts of polysiloxane epoxy resin, 50 parts of filler, 12 parts of diluent, 0.3 parts of defoamer, and 3 parts of coupling agent; and component B comprises the following raw materials in parts by weight: 60 parts of curing agent, 50 parts of siloxane polyimide, 5 parts of catalyst, and 0.3 parts of defoamer.

[0055] The filler is composed of silanized carbon nanotubes and organomontmorillonite in a mass ratio of 5:1. The diameter and aspect ratio of the silanized carbon nanotubes are 2 nm and 4:1, respectively, and the thickness of the organomontmorillonite is 2 nm.

[0056] The preparation method of the siloxane polyimide includes the following steps:

[0057] (1) Heat tetrahydrofuran in a distillation apparatus while passing nitrogen gas through it. After the distillate is mixed with benzophenone and sodium to form a dark blue liquid, put the distillate into a dry reaction apparatus that is passed nitrogen gas through it.

[0058] (2) Add polyimide to the reaction apparatus and place it in an ice bath. Then add γ-aminopropyltriethoxysilane and stir to mix. Then heat up, add catalyst and dehydrating agent, mix and keep warm. After cooling to room temperature, wash with petroleum ether and put into a vacuum drying oven to dry to obtain siloxane polyimide.

[0059] The heating temperature in step (1) is 72°C, the mass ratio of the distillate to benzophenone and sodium is 10:0.5:0.3, and the mass ratio of the distillate to polyimide, γ-aminopropyltriethoxysilane, catalyst and dehydrating agent in step (2) is 7:2:3:0.2:1.5, wherein the catalyst is acetic anhydride-pyridine and the dehydrating agent is isoquinoline.

[0060] In step (2), the mixing temperature and time are 0℃ and 2h, respectively. The heating refers to heating to 50℃. The heat preservation time is 10h. The drying temperature and time are 60℃ and 5h, respectively.

[0061] The polysiloxane epoxy resin is a branched polysiloxane epoxy resin, and the molecular weight of the branched polysiloxane epoxy resin is 2000.

[0062] The diluent is benzyl alcohol, the defoamer is BYK-019, the coupling agent is KH560, the catalyst is stannous octoate, and the curing agent is an aromatic amine curing agent.

[0063] The preparation method of the impact-resistant hinge joint repair epoxy structural adhesive is as follows: Component A raw material is stirred at high speed according to the weight parts to obtain a viscous component A, and component B raw material is stirred at low speed according to the weight parts to obtain a viscous component B. Then, the viscous component A and viscous component B are mixed at a mass ratio of 2:1, and the mixture is degassed under vacuum to obtain the impact-resistant hinge joint repair epoxy structural adhesive. The high-speed stirring speed and time are 1200 r / min and 5 min, respectively, and the low-speed stirring speed and time of component B are 500 r / min and 5 min, respectively.

[0064] The preparation method of the polysiloxane epoxy resin includes the following steps:

[0065] A1: 3-glycidyl etheroxypropyltrimethoxysilane, diphenyl cinnamoethylene glycol and barium hydroxide were mixed and stirred in a mass ratio of 20:27:0.1 under nitrogen gas. The mixture was then heated to 80°C and kept at that temperature for 6 hours. After the gas was removed, the mixture was dried in a vacuum at 60°C for 4 hours to obtain a viscous liquid.

[0066] A2: Mix E-51 bisphenol A type epoxy resin, viscous liquid, and curing agent in a mass ratio of 4:1:3.8, heat to 60℃ and stir for 30 minutes, then cool to room temperature to obtain polysiloxane epoxy resin.

[0067] The curing agent in step A2 is prepared by heating and stirring methylhexahydrophthalic anhydride and tetraethylammonium bromide at a mass ratio of 50:1 at 60°C for 30 minutes.

[0068] The method for preparing the silanized carbon nanotubes is as follows: carbon nanotubes are oxidized in a mixed acid, then stirred in a silane coupling agent solution, and dried to obtain silanized carbon nanotubes. The mass ratio of the carbon nanotubes, the mixed acid, and the silane coupling agent solution is 1:3:4, wherein the mixed acid is composed of concentrated nitric acid and concentrated nitric acid in a mass ratio of 3:1, and the silane coupling agent solution is a 2 mmol / L γ-aminopropyltriethoxysilane ethanol solution.

[0069] Comparative Example 1

[0070] Based on Example 2, the polysiloxane epoxy resin was removed and replaced with an equal part by weight of bisphenol A type epoxy resin, while other conditions remained the same as in Example 2.

[0071] Comparative Example 2

[0072] Based on Example 2, the siloxane polyimide was removed and replaced with an equal part by weight of curing agent, while other conditions remained the same as in Example 2.

[0073] Comparative Example 3

[0074] Based on Example 2, step (1) in the preparation of siloxane polyimide was removed, and tetrahydrofuran was directly added to the reaction apparatus, while other conditions remained the same as in Example 2.

[0075] Comparative Example 4

[0076] Based on Example 2, the mass ratio of silanized carbon nanotubes and organomontmorillonite was adjusted to 6:0.5, while other conditions remained the same as in Example 2.

[0077] Comparative Example 5

[0078] Based on Example 2, the mass ratio of silanized carbon nanotubes and organomontmorillonite was adjusted to 3:2, while other conditions remained the same as in Example 2.

[0079] Comparative Example 6

[0080] Based on Example 2, silanized carbon nanotubes with a diameter of 3 nm were used, and other conditions remained the same as in Example 2.

[0081] Comparative Example 7

[0082] Based on Example 2, an organomontmorillonite with a thickness of 3 nm was used, while other conditions remained the same as in Example 2.

[0083] Performance testing

[0084] Sample preparation: P·O42.5 ordinary Portland cement was used as the cement material, natural medium sand was used as the fine aggregate, and good natural crushed stone with a particle size of 5~20mm was used as the coarse aggregate. Ordinary tap water was used as the water. The standard specimens of 100mm×100mm×100mm were prepared by mixing according to the commonly used C30 concrete mix proportion. The specimens were cured indoors at (23±2)℃ for 28 days in a curing box with the water depth greater than half the height of the base block.

[0085] Sagging distance: After repeatedly wiping the glass surface with acetone until smooth and drying it, place it outdoors in sunlight for 2 hours until the glass temperature reaches 30°C, and place it vertically; apply the structural adhesive prepared in Examples 1-3 and Comparative Examples 1-7 to the glass surface (adhesive amount is 10 g, adhesive size is 40 mm × 50 mm × 3 mm, glass plate size is 150 mm × 50 mm), and measure its sagging distance after 30 minutes of adhesive application;

[0086] Mechanical strength determination: Examples 1-3 and Comparative Examples 1-7 were used as samples, and their flexural strength and bending strength were tested according to the standard DL5193. The test conditions were (23±2)℃ for 7 days.

[0087] Steel-concrete tensile bond strength determination: Examples 1-3 and Comparative Examples 1-7 were determined according to Appendix G of GB50728, under the conditions of (23±2)℃ for 7 days;

[0088] The test results are shown in Table 1.

[0089] Table 1 Test Results:

[0090] Analysis of the results in Table 1 shows that neither Examples 1-3 nor Comparative Examples 1-7 exhibited sagging. The flexural strength, bending strength, and steel-concrete tensile bond strength of Examples 1-3 were superior to those of Comparative Examples 1-7. Comparative Examples 1-2, lacking the addition of polysiloxane epoxy resin or siloxane polyimide, failed to form a double cross-linked structure in the structural adhesive, significantly weakening its mechanical strength. Comparative Example 3, lacking a dehydration step, allowed tetrahydrofuran to easily absorb moisture from the air, while the coupling agent was prone to hydrolysis, leading to instability. Comparative Examples 4-5 showed a different mass ratio between silanized carbon nanotubes and organomontmorillonite. When the density of silanized carbon nanotubes increases, the limited organomontmorillonite cannot be separated from them, and the orientation of silanized carbon nanotubes is enhanced, making them prone to forming bundles, thus weakening the mechanical strength. When the density of organomontmorillonite increases, they are prone to stacking, thus weakening the mechanical properties. As can be seen from the table, the mechanical properties are optimal when the mass ratio of the two in Example 2 is 4:0.7. In Comparative Examples 6-7, when the diameter of silanized carbon nanotubes or the thickness of organomontmorillonite is increased, the two cannot interweave in the epoxy resin molecular chain and cannot form a line-surface distribution, thus reducing the mechanical strength.

[0091] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An impact-resistant epoxy structural adhesive for repairing hinge joints, characterized in that, The impact-resistant hinge repair epoxy structural adhesive consists of component A and component B. Component A includes the following raw materials in parts by weight: 50-60 parts of bisphenol A epoxy resin, 50-70 parts of polysiloxane epoxy resin, 30-50 parts of filler, 8-12 parts of diluent, 0.1-0.3 parts of defoamer, and 1-3 parts of coupling agent. Component B includes the following raw materials in parts by weight: 40-60 parts of curing agent, 40-50 parts of siloxane polyimide, 2-5 parts of catalyst, and 0.1-0.3 parts of defoamer.

2. The impact-resistant epoxy structural adhesive for repairing hinge joints according to claim 1, characterized in that, The filler is composed of silanized carbon nanotubes and organomontmorillonite in a mass ratio of 3-5:0.5-1. The diameter and aspect ratio of the silanized carbon nanotubes are 0.8-2 nm and 2-4:1, respectively, and the thickness of the organomontmorillonite is 1-2 nm.

3. The impact-resistant epoxy structural adhesive for repairing hinge joints according to claim 1, characterized in that, The preparation method of the siloxane polyimide includes the following steps: (1) Take tetrahydrofuran and heat it in a distillation apparatus while passing nitrogen gas through it. After the distillate is mixed with benzophenone and sodium to form a dark blue liquid, put the distillate into a dry reaction apparatus that is passed nitrogen gas through it; (2) Add polyimide to the reaction apparatus and place it in an ice bath. Then add γ-aminopropyltriethoxysilane and stir to mix. Then heat up and add catalyst and dehydrating agent to mix and keep warm. After cooling to room temperature, wash with petroleum ether and put it into a vacuum drying oven to dry to obtain siloxane polyimide.

4. The impact-resistant epoxy structural adhesive for repairing hinge joints according to claim 3, characterized in that, The heating temperature in step (1) is 68-72℃, the mass ratio of the distillate to benzophenone and sodium is 10:0.2-0.5:0.3, and the mass ratio of the distillate to polyimide, γ-aminopropyltriethoxysilane, catalyst and dehydrating agent in step (2) is 5-7:1.5-2:3:0.1-0.2:1-1.5, wherein the catalyst is acetic anhydride-pyridine and the dehydrating agent is isoquinoline.

5. The impact-resistant epoxy structural adhesive for repairing hinge joints according to claim 3, characterized in that, The mixing temperature and time in step (2) are -1~0℃ and 2h, respectively. The heating refers to heating to 40-50℃. The heat preservation time is 8-10h. The drying temperature and time are 55-60℃ and 3-5h, respectively.

6. The impact-resistant epoxy structural adhesive for repairing hinge joints according to claim 1, characterized in that, The polysiloxane epoxy resin is a branched polysiloxane epoxy resin, and the molecular weight of the branched polysiloxane epoxy resin is 1000-2000.

7. The impact-resistant epoxy structural adhesive for repairing hinge joints according to claim 1, characterized in that, The diluent is benzyl alcohol, the defoamer is BYK-019, the coupling agent is KH560, the catalyst is stannous octoate, and the curing agent is an aromatic amine curing agent.

8. A method for preparing an impact-resistant hinge joint repair epoxy structural adhesive as described in claim 1, characterized in that, The preparation method of the impact-resistant hinge joint repair epoxy structural adhesive is as follows: Component A raw material is stirred at high speed according to the weight parts to obtain a viscous component A, and component B raw material is stirred at low speed according to the weight parts to obtain a viscous component B. Then, the viscous component A and viscous component B are mixed at a mass ratio of 1.5-2:1, and the mixture is degassed under vacuum to obtain the impact-resistant hinge joint repair epoxy structural adhesive. The high-speed stirring time is 1000-1200 r / min and 3-5 min, respectively, and the low-speed stirring speed and time of component B are 400-500 r / min and 3-5 min, respectively.

Images