Epoxy resin structural adhesive for connecting and sealing high-strength prefabricated pipe pile and preparation method of epoxy resin structural adhesive

Abstract

The invention provides an epoxy resin structural adhesive for connecting and sealing a high-strength prefabricated pipe pile and a preparation method thereof, and relates to the technical field of building adhesive materials, the epoxy resin structural adhesive comprises a component A and a component B in a mass ratio of (4-6): 1, the component A comprises the following components in percentage by mass: 30-50% of epoxy resin, 5-15% of polyurethane modified epoxy resin, 0.05-0.30% of a coupling agent, 3-10% of a reactive diluent, 30-45% of functional filler, 1-5% of an auxiliary agent and 3-6% of fumed silica; the component B is prepared from the following components in percentage by mass: 5 to 40 percent of a compound amine curing agent, 40 to 65 percent of functional filler, 0.05 to 0.30 percent of a coupling agent, 15 to 18 percent of nano aluminum oxide, 0.8 to 1.2 percent of a tertiary amine accelerant, 0.5 to 3.0 percent of a reactive diluent and 0.05 to 0.30 percent of an auxiliary agent. The problems that traditional epoxy glue is insufficient in compression resistance, poor in corrosion resistance and the like are solved.

Description

Technical Field

[0001] The invention relates to the technical field of building adhesive materials, in particular to an epoxy resin structural adhesive for high-strength prefabricated pipe pile connection and sealing and a preparation method thereof. Background Art

[0002] In the application of traditional epoxy resin structural adhesive, there are three common technical bottlenecks: first, insufficient compressive strength. Due to the imbalance of epoxy resin and curing agent ratio and limited filler reinforcement effect, the compressive strength of conventional formulas after curing is mostly lower than 60MPa, which is difficult to meet the high load requirements of prestressed pipe pile interface (>80MPa), and it is easy to cause interface peeling failure; second, weak corrosion resistance. Especially in the coastal high salt fog environment, the unmodified epoxy system has residual hydrophilic groups and unblocked chloride ion permeation channels. After 500 hours of salt spray test, the bonding strength decays by more than 30%, resulting in a significant increase in the risk of sealing failure; third, improper rheological properties are improperly regulated. The existing thixotropic agent addition method is extensive (such as direct dry mixing of fumed silica), resulting in a low thixotropic index (<3.5) and a sag of >3mm. It is difficult to achieve self-leveling filling during construction, and residual gaps are prone to form water seepage hazards at the connection of pipe piles. These problems seriously restrict the long-term reliability of pipe pile structures under complex working conditions, and it is urgent to achieve breakthroughs through material system innovation and process optimization.

[0003] In view of this, the present invention is proposed. Summary of the invention

[0004] The purpose of the present invention is to provide a high-strength epoxy resin structural adhesive for prefabricated pipe pile connection sealing and a preparation method thereof. Through material innovation and process optimization, the pain points of traditional epoxy adhesives such as insufficient compressive resistance, poor corrosion resistance, and difficult construction are solved. It has the advantages of high strength, super corrosion resistance, easy construction and low cost, and provides a high-reliability sealing solution for harsh scenarios such as marine engineering and bridge pile foundations.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides an epoxy resin structural adhesive for high-strength prefabricated pipe pile connection and sealing, comprising component A and component B in a mass ratio of (4-6):1;

[0007] Taking the mass of component A as 100%, the component A comprises 30-50% of epoxy resin, 5-15% of polyurethane modified epoxy resin, 0.05-0.30% of coupling agent, 3-10% of active diluent, 30-45% of functional filler, 1-5% of auxiliary agent and 3-6% of fumed silica;

[0008] Based on the mass of component B being 100%, component B includes 5 - 40% of composite amine curing agent, 40 - 65% of functional filler, 0.05 - 0.30% of coupling agent, 15 - 18% of nano-aluminum oxide, 0.8 - 1.2% of tertiary amine accelerator, 0.5 - 3.0% of active diluent, and 0.05 - 0.30% of additives.

[0009] Further, on the basis of the above technical solution, the epoxy resin includes one or more of bisphenol A epoxy resin, hydrogenated bisphenol A epoxy resin, and phenolic epoxy resin;

[0010] and / or, the polyurethane-modified epoxy resin is SL3411 toughened polyurethane-modified epoxy resin;

[0011] and / or, the additives include one or more of rheological agents and defoamers;

[0012] and / or, the active diluent includes one or more of dodecyl to tetradecyl glycidyl ether, cardanol glycidyl ether, cyclohexanediol diglycidyl ether, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol tetraglycidyl ether;

[0013] and / or, the functional filler includes 50 - 100 mesh quartz sand, 200 - 400 mesh quartz sand, and 800 - 1000 mesh silica powder with a mass ratio of (1 - 2):1:(3 - 5);

[0014] and / or, the particle size of the fumed silica is 7 - 40 nm.

[0015] Further, on the basis of the above technical solution, the composite amine curing agent includes polyamide epoxy resin curing agent, modified aliphatic amine curing agent, and aromatic modified amine curing agent with a mass ratio of 1:1:(2 - 5);

[0016] The polyamide curing agent includes one or more of Versamid 140, Ancamide 500 - A, or Aradur 250;

[0017] The modified aliphatic amine curing agent includes one or more of Ancamine 2014FG, Cardolite NX - 5451, or Aradur2963;

[0018] The aromatic modified amine curing agent includes one or more of D.E.H.85, Epikure 3115, or Aradur 917;

[0019] and / or, the coupling agent includes at least one of silane coupling agent KH - 560h or silane coupling agent KH - 550;

[0020] And / or, the tertiary amine accelerator includes one or more of 2,4,6-tris(dimethylaminomethyl)phenol, benzyldimethylamine, and dimethylaminomethylphenol;

[0021] And / or, the particle size of the nano-aluminum oxide is 30-50 nm, and the specific surface area > 180 m 2 / g.

[0022] The present invention also provides a preparation method of the epoxy resin structural adhesive for connecting and sealing high-strength precast pipe piles as described above, including the following steps:

[0023] S1: Preheat the epoxy resin and the polyurethane-modified epoxy resin to obtain a mixed resin;

[0024] S2: Add an active diluent to the mixed resin, perform a first stirring, then add a part of fumed silica for a second stirring, and further add a filler for a third stirring to obtain a first mixed material;

[0025] S3: Pre-mix the coupling agent with the remaining fumed silica to obtain a second mixed material, spray the second mixed material into the first mixed material, perform a fourth stirring, and finally perform vacuum defoaming to obtain the A-component material;

[0026] S4: Activate the composite amine curing agent to obtain an activated amine curing agent;

[0027] S5: Pre-mix the nano-aluminum oxide with the coupling agent to obtain a third mixed material, add the third mixed material to the activated amine curing agent, perform a fifth stirring, then add the tertiary amine accelerator, perform a sixth stirring, and finally perform homogenization treatment and vacuum defoaming to obtain the B-component material;

[0028] S6: Mix the A-component material with the B-component material to obtain the epoxy resin structural adhesive for connecting and sealing high-strength precast pipe piles.

[0029] Further, on the basis of the above technical solution, in step S1, the preheating temperature is 45-55 °C, the preheating time is 20-35 min, and the viscosity of the mixed resin is 800-1000 mPa·s.

[0030] Further, on the basis of the above technical solution, in step S2, the speed of the first stirring is 150-200 rpm, and the time is 5-10 min;

[0031] And / or, in step S2, the part of fumed silica added accounts for 40-55% of the total mass of the fumed silica;

[0032] And / or, in step S2, the speed of the second stirring is 1000 - 1200 rpm, the time is 10 - 15 min, and the temperature ≤ 50°C;

[0033] And / or, in step S2, the speed of the third stirring is 800 - 1000 rpm, and the time is 10 - 15 min;

[0034] And / or, in step S2, the filler is added in batches, with an interval of 2 - 3 min each time.

[0035] Further, on the basis of the above technical solution, in step S3, the stirring speed of the premixing is 500 - 600 rpm, and the time is 10 - 15 min;

[0036] And / or, in step S3, the spraying method is atomized spraying, the pressure of the atomized spraying is 0.3 - 0.5 MPa, and the second mixed material is atomized into droplets of 50 - 100 μm;

[0037] And / or, in step S3, the fourth stirring speed is 500 - 600 rpm, and the time is 10 - 15 min;

[0038] And / or, in step S3, the vacuum degassing includes:

[0039] The pressure is -0.03 to -0.01 MPa, the temperature is 35 - 45°C, the time is 20 - 25 min, and the bubble volume fraction < 0.5%.

[0040] Further, on the basis of the above technical solution, in step S4, the activation includes the following steps:

[0041] Stir and heat the composite amine curing agent at a rotation speed of 150 - 200 rpm to 40 - 50°C, and then introduce nitrogen to remove water for 30 min to obtain the activated amine curing agent;

[0042] The volume percentage of water in the activated amine curing agent in the total volume of the activated amine curing agent ≤ 0.3%.

[0043] Further, on the basis of the above technical solution, in step S5, the nano-aluminum oxide and the coupling agent are premixed on a ball mill at a mass ratio of 8 - 10:1, the ball milling speed is 250 - 350 rpm, and the ball milling time is 2 - 2.5 h;

[0044] And / or, in step S5, the stirring speed of the fifth stirring is 400 - 500 rpm, and the time is 15 - 20 min;

[0045] And / or, in step S5, adding the third mixed material to the activated amine curing agent in batches, with an interval of 2-3 minutes each time;

[0046] And / or, in step S5, the stirring speed of the sixth stirring is 100-200 rpm, and the time is 10-15 minutes;

[0047] And / or, in step S5, the homogenization treatment means high-speed dispersion at a rotational speed of 1000-1500 rpm for 5-10 minutes;

[0048] And / or, in step S5, the vacuum degassing includes:

[0049] The pressure is -0.09 to -0.05 MPa, the temperature is 35-45 °C, the time is 10-15 minutes, and the bubble volume fraction <0.5%.

[0050] Furthermore, on the basis of the above technical solution, in step S6, the component A material and the component B material are mixed at a temperature of 10-35 °C for 5-10 minutes by using a static mixer or a twin-screw continuous mixer.

[0051] An epoxy resin structural adhesive for connecting and sealing high-strength precast pipe piles and a preparation method thereof provided by the present invention have the following beneficial effects:

[0052] 1. The epoxy resin structural adhesive for connecting and sealing high-strength precast pipe piles provided by the present invention has a high crosslinking density of the curing network, its compressive strength can reach 85.7 MPa, while maintaining its elongation at break >4%, and the thixotropic index is 4.8, ensuring that the pipe pile interface construction has both anti-sagging properties (sag <1 mm) and self-leveling ability (fully wetting the interface within 30 seconds), so that the connection of the pipe piles is sealed without voids.

[0053] 2. By adding silica powder to the filler, the present invention can effectively fill the sub-micron pores of the epoxy resin matrix, improve the density of the composite material. The silica powder can also form a "nano-core - micron-shell" structure with fumed silica, which can effectively improve the mechanical properties of the material. And the silica powder can form a tortuous penetration path in the curing system, reducing the diffusion of chloride ions, thereby effectively improving the salt spray resistance of the material.

[0054] 3. By adding fumed silica, the reversible formation and destruction of its hydrogen bond network endow the epoxy resin structural adhesive with thixotropic properties of "high viscosity at rest, low viscosity under shear", thus realizing the key properties of self-leveling filling, anti-sagging and void elimination in the application of pipe pile sealing. At the same time, the interfacial bonding strength and corrosion resistance are optimized through surface modification. Specific embodiments

[0055] To make the objectives, technical solutions and advantages of the present invention clearer, the following will, in conjunction with the embodiments of the present invention, clearly and completely describe the technical solutions in the embodiments of the present invention. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention. For the process parameters without specific conditions noted in the following embodiments, they are generally in accordance with conventional conditions.

[0056] In the ranges disclosed in the present invention, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in the present invention.

[0057] According to the first aspect of the present invention, there is provided an epoxy resin structural adhesive for connecting and sealing high-strength precast pipe piles, including component A and component B with a mass ratio of (4 - 6):1, such as 4.5:1, 5:1, 5.5:1, etc.

[0058] Based on the mass of component A being 100%, component A includes 30 - 50% epoxy resin (such as 35%, 40%, 45%, etc.), 5 - 15% polyurethane-modified epoxy resin (such as 7%, 10%, 13%, etc.), 0.05 - 0.30% coupling agent (such as 0.1%, 0.15%, 0.2%, 0.25%, etc.), 3 - 10% active diluent (such as 5%, 7%, 9%, etc.), 30 - 45% functional filler (such as 33%, 35%, 38%, 40%, 42%, etc.), 1 - 5% auxiliary agent (such as 2%, 3%, 4%, etc.), 3 - 6% fumed silica (such as 3.5%, 4%, 4.5%, 5%, 5.5%, etc.).

[0059] Based on the mass of component B being 100%, component B includes 5 - 40% composite amine curing agent (such as 10%, 20%, 30%, 35%, etc.), 40 - 65% functional filler (such as 45%, 50%, 55%, 60%, etc.), 0.05 - 0.30% coupling agent (such as 0.1%, 0.2%, 0.25%, etc.), 15 - 18% nano-aluminum oxide (such as 15.5%, 16%, 16.5%, 17%, 17.5%, etc.), 0.8 - 1.2% tertiary amine accelerator (such as 1%, 1.1%, etc.), 0.5 - 3.0% active diluent (such as 1%, 2%, 2.5%, etc.), 0.05 - 0.30% auxiliary agent (such as 0.1%, 0.2%, etc.).

[0060] Specifically, the present invention defines the mass ratio of component A to component B as (4 - 6):1 because under this mass ratio condition, the crosslinking density of the curing network of the epoxy resin structural adhesive for connecting and sealing high-strength precast pipe piles can be maximized, so that its compressive strength can reach 85.7 MPa, while maintaining its elongation at break > 4%, thixotropic index of 4.8, ensuring that the pipe pile interface has both anti-sagging property (sag < 1 mm) and self-leveling ability (fully infiltrating the interface within 30 seconds) during construction, and making the connection of the pipe piles sealed without voids.

[0061] As an alternative embodiment of the present invention, the epoxy resin includes one or more of bisphenol A epoxy resin, hydrogenated bisphenol A epoxy resin, and phenolic epoxy resin;

[0062] The polyurethane-modified epoxy resin is SL3411 toughened polyurethane-modified epoxy resin;

[0063] The auxiliary agents include one or more of a rheological agent and an antifoaming agent; typically and non-limitingly, the auxiliary agents are rheological agents, antifoaming agents, etc. commonly used in the art. The rheological agent is an organically modified flaky silicate BYK1958; the antifoaming agent is BYKA530.

[0064] The active diluent includes one or more of dodecyl to tetradecyl glycidyl ether, cardanol glycidyl ether, cyclohexanediol diglycidyl ether, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol tetraglycidyl ether;

[0065] The functional filler includes quartz sand with a particle size of 50 - 100 mesh, quartz sand with a particle size of 200 - 400 mesh, and silica powder with a particle size of 800 - 1000 mesh (such as 850 mesh, 900 mesh, 950 mesh, etc.) in a mass ratio of (1 - 2):1:(3 - 5) (such as 1.5:1:4, 1:1:3.5, 2:1:4.5, etc.); typically and non-limitingly, the present invention doped silica powder with a particle size of 800 - 1000 mesh in the filler because adding silica powder can effectively fill the sub-micron pores of the epoxy resin matrix, improve the density of the composite material, and silica powder can also form a "nano-core - micron-shell" structure with fumed silica, which can effectively improve the mechanical properties of the material, and silica powder can form a tortuous penetration path in the curing system, reducing the diffusion of chloride ions, thereby effectively improving the salt spray resistance of the material.

[0066] The particle size of the fumed silica is 7-40 nm (such as 10 nm, 20 nm, 30 nm, 35 nm, etc.). The fumed silica endows the epoxy resin structural adhesive with the thixotropic property of "high viscosity at rest and low viscosity under shear" through the reversible formation and destruction of the hydrogen bond network, thus realizing the key properties of self-leveling filling, anti-sagging and void elimination in the application of pipe pile sealing. At the same time, the interfacial bonding strength and corrosion resistance are optimized through surface modification.

[0067] As an alternative embodiment of the present invention, the composite amine curing agent comprises a polyamide epoxy resin curing agent, a modified aliphatic amine curing agent and an aromatic modified amine curing agent in a mass ratio of 1:1:(2-5) (such as 1:1:3, 1:1:4, etc.);

[0068] The polyamide curing agent comprises one or more of Versamid 140, Ancamide 500-A or Aradur 250;

[0069] The modified aliphatic amine curing agent comprises one or more of Ancamine 2014FG, Cardolite NX-5451 or Aradur2963;

[0070] The aromatic modified amine curing agent comprises one or more of D.E.H.85, Epikure 3115 or Aradur 917.

[0071] Specifically, the present invention adopts a composite amine curing agent and defines the mass ratio of the polyamide epoxy resin curing agent, the modified aliphatic amine curing agent and the aromatic modified amine curing agent as 1:1:(2-5) because, under the limitation of this mass ratio, the polyamide curing agent can construct a crosslinking network in the middle stage of curing (69-90 min); the modified aliphatic amine can quickly construct a crosslinking skeleton in the initial stage of curing (0-30 minutes); the aromatic modified amine can complete deep crosslinking in the later stage of curing (6-24 h). The composite use of the three curing agents can make the compressive strength of the prepared composite material greater than 80 MPa.

[0072] The coupling agent comprises at least one of silane coupling agent KH-560 or silane coupling agent KH-550;

[0073] The tertiary amine accelerator comprises one or more of 2,4,6-tris(dimethylaminomethyl)phenol, benzyldimethylamine, dimethylaminomethylphenol;

[0074] Specifically, the present invention adopts a tertiary amine accelerator because the lone pair electrons in the tertiary amine molecule can attack the oxygen atom in the epoxy group to form an oxygen anion intermediate, significantly reducing the activation energy of the ring-opening reaction and accelerating the hydrogen transfer reaction of the amine curing agent, thereby forming a more uniform crosslinking network.

[0075] The particle size of the nano-aluminum oxide is 30-50 nm (such as 35 nm, 40 nm, 45 nm, etc.), and the specific surface area > 180 m 2 / g, such as 200 m 2 / g, 250 m 2 / g, 300 m 2 / g, etc.

[0076] Specifically, the particle size of the nano-aluminum oxide is defined as 30-50 nm in the present invention because the nano-aluminum oxide with a particle size of 30-50 nm can effectively penetrate the molecular chain gaps of the epoxy resin (the chain spacing is about 5-10 nm), enhance the interfacial bonding strength through the "pinning effect", and can also form a "nano-micron" composite system with the filler, making the tortuosity coefficient of the chloride ion penetration path larger, thereby effectively improving the salt spray resistance of the composite material; too large a particle size of the nano-aluminum oxide will lead to an increase in the porosity of the barrier network, while too small a particle size of the nano-aluminum oxide will cause a sharp increase in the resin-particle frictional resistance due to the high specific surface area.

[0077] According to the second aspect of the present invention, a preparation method of an epoxy resin structural adhesive for connecting and sealing high-strength precast pipe piles as described above is provided, including the following steps:

[0078] S1: Preheat the epoxy resin and the polyurethane-modified epoxy resin to obtain a mixed resin;

[0079] S2: Add an active diluent to the mixed resin, perform the first stirring, then add part of the fumed silica for the second stirring, and further add the filler for the third stirring to obtain a first mixed material;

[0080] S3: Pre-mix the coupling agent with the remaining fumed silica to obtain a second mixed material, spray the second mixed material into the first mixed material, perform the fourth stirring, and finally perform vacuum defoaming to obtain the A-component material;

[0081] S4: Activate the composite amine curing agent to obtain an activated amine curing agent;

[0082] S5: Pre-mix the nano-aluminum oxide with the coupling agent to obtain a third mixed material, add the third mixed material to the activated amine curing agent, perform the fifth stirring, then add the tertiary amine accelerator for the sixth stirring, and finally perform homogenization treatment and vacuum defoaming to obtain the B-component material;

[0083] S6: Mix the A-component material with the B-component material to obtain an epoxy resin structural adhesive for connecting and sealing high-strength precast pipe piles.

[0084] As an alternative embodiment of the present invention, in step S1, the preheating temperature is 45 - 55°C, the preheating time is 20 - 35 min, and the viscosity of the mixed resin is 800 - 1000 mPa·s.

[0085] Specifically, after preheating, the resin viscosity decreases from 1500 - 2000 mPa·s at room temperature to 800 - 1000 mPa·s. At a lower viscosity, the filler is more easily dispersed by the shear force, reducing the shear energy consumption during filler dispersion and improving the dispersion uniformity.

[0086] As an alternative embodiment of the present invention, in step S2, the speed of the first stirring is 150 - 200 rpm, and the time is 5 - 10 min;

[0087] In step S2, the proportion of the added partial fumed silica accounts for 40 - 55% (such as 45%, 50%, 53%, etc.) of the total mass of the fumed silica;

[0088] Specifically, the purpose of first adding a part of the fumed silica and then adding the remaining fumed silica in the present invention is to construct a three-dimensional thixotropic network in a gradient manner and synergistically modify the interface. Specifically:

[0089] (1) In step S2, adding a part of the fumed silica first is to break the fumed silica under high-speed stirring, avoid secondary agglomeration when adding the subsequent filler, and form a preliminary hydrogen bond network, providing a structural framework for the subsequent addition and reducing the initial viscosity of the system;

[0090] (2) Adding the remaining fumed silica in step S3 and premixing it with the fumed silica through a coupling agent is to react the silane coupling agent with the hydroxyl groups on the surface of the fumed silica to form Si - O - Si bonds, thereby improving the bonding strength between the fumed silica and the resin; and the subsequently added fumed silica can fill the gaps in the preformed network, hinder the migration path of chloride ions, improve the salt spray resistance of the material, and also increase the final thixotropic index to 4.8, with a sagging degree < 1 mm; in addition, by adding the fumed silica in two steps, the viscosity of the whole system can rise smoothly, avoiding a significant increase in the viscosity of the whole system caused by a one-time addition, which affects the performance of the material and makes it difficult to achieve self-leveling filling during construction.

[0091] In step S2, the speed of the second stirring is 1000 - 1200 rpm, the time is 10 - 15 min, and the temperature ≤ 50°C;

[0092] In step S2, the speed of the third stirring is 800 - 1000 rpm, and the time is 10 - 15 min;

[0093] In step S2, the filler is added in batches, with an interval of 2 - 3 min each time.

[0094] As an alternative embodiment of the present invention, in step S3, the stirring speed of the premixing is 500 - 600 rpm, and the time is 10 - 15 min;

[0095] In step S3, the spraying method is atomized spraying, the pressure of the atomized spraying is 0.3 - 0.5 MPa, and the second mixed material is atomized into droplets with a size of 50 - 100 μm;

[0096] In step S3, the fourth stirring speed is 500 - 600 rpm, and the time is 10 - 15 min;

[0097] In step S3, the vacuum degassing includes:

[0098] The pressure is -0.03 to -0.01 MPa, the temperature is 35 - 45 °C, the time is 20 - 25 min, and the bubble volume fraction < 0.5%.

[0099] As an alternative embodiment of the present invention, in step S4, the activation includes the following steps:

[0100] The composite amine curing agent is stirred and heated to 40 - 50 °C at a rotation speed of 150 - 200 rpm, and then nitrogen is introduced to remove water for 30 min to obtain an activated amine curing agent; water will react with the primary / secondary amine groups in the amine curing agent to form inactive amino alcohols, resulting in a decrease in the effective amine hydrogen concentration and a decrease in the curing crosslinking density. Therefore, a water removal operation is required;

[0101] The volume percentage of water in the activated amine curing agent in the total volume of the activated amine curing agent ≤ 0.3%.

[0102] As an alternative embodiment of the present invention, in step S5, the nano-aluminum oxide and the coupling agent are premixed on a ball mill at a mass ratio of 8 - 10:1, the ball milling speed is 250 - 350 rpm, and the ball milling time is 2 - 2.5 h;

[0103] Specifically, in the present invention, the nano-aluminum oxide and the coupling agent are first premixed, aiming to modify the surface of the nano-aluminum oxide with the coupling agent, which not only improves the dispersibility of the nano-aluminum oxide, but also forms a uniformly dispersed three-dimensional barrier network in the epoxy matrix, thereby effectively blocking the penetration of chloride ions and significantly improving the salt spray resistance of the material.

[0104] In step S5, the stirring speed of the fifth stirring is 400 - 500 rpm, and the time is 15 - 20 min;

[0105] In step S5, the third mixed material is added to the activated amine curing agent in batches, with an interval of 2 - 3 min each time;

[0106] In step S5, the stirring speed of the sixth stirring is 100 - 200 rpm, and the time is 10 - 15 min;

[0107] In step S5, the homogenization treatment means high-speed dispersion at a rotation speed of 1000 - 1500 rpm for 5 - 10 min;

[0108] In step S5, the vacuum degassing includes:

[0109] The pressure is -0.09 to -0.05 MPa, the temperature is 35 - 45 °C, the time is 10 - 15 min, and the bubble volume fraction < 0.5%.

[0110] Specifically, the purpose of performing vacuum degassing in both step S3 and step S5 of the present invention is to completely eliminate the residual bubbles in the colloid through a negative pressure environment to ensure the mechanical properties, interface sealing performance, and long-term durability of the material.

[0111] As an optional implementation manner of the present invention, in step S6, the component A material and the component B material are mixed at a temperature of 10 - 35 °C for 5 - 10 min using a static mixer or a twin-screw continuous mixer.

[0112] The present invention will be further described in detail below with specific examples and comparative examples.

[0113] Example 1

[0114] The epoxy resin structural adhesive for connecting and sealing high-strength precast pipe piles includes component A and component B with a mass ratio of 4:1;

[0115] Based on the mass of component A being 100%, component A includes 40% bisphenol A epoxy resin, 10% SL3411 toughened polyurethane modified epoxy resin, 0.10% coupling agent (KH-560 and KH-550 with a mass ratio of 1:1), 3.9% glycerol triglycidyl ether, 40% functional filler (50-mesh quartz sand, 400-mesh quartz sand, and 800-mesh silica powder with a mass ratio of 2:1:3), 3% auxiliary agent (organically modified flaky silicate BYK1958, BYKA530), and 3% fumed silica (particle size of 30 nm);

[0116] Based on the mass of component B being 100%, component B includes 35% of a composite amine curing agent (Versamid 140, Ancamine 2014FG, and D.E.H. 85 with a mass ratio of 1:1:3), 45.5% of a functional filler (50-mesh quartz sand, 400-mesh quartz sand, and 800-mesh silica powder with a mass ratio of 2:1:3), 0.20% of a coupling agent (KH-560 and KH-550 with a mass ratio of 1:1), 16% of nano-aluminum oxide (particle size of 40 nm and specific surface area of 250 m 2 / g), 1% of 2,4,6-tris(dimethylaminomethyl)phenol, 2.0% of glycerol triglycidyl ether, and 0.30% of an auxiliary agent (organically modified plate-like silicate BYK1958, BYKA530).

[0117] A preparation method of an epoxy resin structural adhesive for connecting and sealing high-strength precast pipe piles includes the following steps:

[0118] S1: Preheat epoxy resin and polyurethane-modified epoxy resin at a temperature of 50°C for 30 min to obtain a mixed resin, and the viscosity of the mixed resin is 950 mPa·s;

[0119] S2: Add an active diluent to the mixed resin, perform a first stirring, then add a part of fumed silica for a second stirring, and further add the filler in 3 batches at intervals of 2 min for a third stirring to obtain a first mixed material;

[0120] Among them, the speed of the first stirring is 200 rpm and the time is 8 min;

[0121] The speed of the second stirring is 1100 rpm, the time is 13 min, and the temperature is 40°C;

[0122] The speed of the third stirring is 900 rpm and the time is 15 min;

[0123] The part of fumed silica added accounts for 50% of the total mass of fumed silica;

[0124] S3: After premixing the coupling agent and the remaining fumed silica, obtain a second mixed material, atomize and spray the second mixed material into the first mixed material for a fourth stirring, and finally perform vacuum degassing to obtain component A material;

[0125] Among them, the stirring speed of the premixing is 600 rpm and the time is 15 min;

[0126] The pressure of the atomizing spray is 0.4 MPa, and the second mixed material is atomized into 50 - 100 μm droplets;

[0127] The fourth stirring speed is 600 rpm and the time is 15 min;

[0128] Vacuum degassing includes:

[0129] The pressure is -0.03 MPa, the temperature is 40 °C, the time is 20 min, and the bubble volume fraction < 0.5%;

[0130] S4: Stir and heat the composite amine curing agent to 50 °C at a rotation speed of 200 rpm, and then introduce nitrogen to remove water for 30 min to obtain an activated amine curing agent;

[0131] The volume percentage of water in the activated amine curing agent accounts for 0.1% of the total volume of the activated amine curing agent;

[0132] S5: Premix the nano-aluminum oxide and the coupling agent at a mass ratio of 10:1 on a ball mill. The ball milling speed is 300 rpm and the ball milling time is 2 h to obtain a third mixed material. Add the third mixed material to the activated amine curing agent in 3 batches, perform the fifth stirring, then add a tertiary amine accelerator, perform the sixth stirring, and finally perform homogenization treatment and vacuum degassing to obtain the B-component material;

[0133] Among them, the stirring speed of the fifth stirring is 500 rpm and the time is 20 min;

[0134] The stirring speed of the sixth stirring is 200 rpm and the time is 15 min;

[0135] Homogenization treatment means high-speed dispersion at a rotation speed of 1500 rpm for 8 min;

[0136] The vacuum degassing includes:

[0137] The pressure is -0.09 MPa, the temperature is 35 °C, the time is 15 min, and the bubble volume fraction < 0.5%.

[0138] S6: Mix the A-component material and the B-component material at a temperature of 25 °C using a static mixer or a twin-screw continuous mixer for 5 min to obtain an epoxy resin structural adhesive for connecting and sealing high-strength precast pipe piles.

[0139] Example 2

[0140] The epoxy resin structural adhesive for connecting and sealing high-strength precast pipe piles includes A and B components with a mass ratio of 5:1;

[0141] Based on the mass of component A being 100%, component A includes 50% phenolic epoxy resin, 5% SL3411 toughened polyurethane modified epoxy resin, 0.30% coupling agent (KH-560 and KH-550 with a mass ratio of 1:1), 5% glycerol triglycidyl ether, 32.7% functional filler (50-mesh quartz sand, 400-mesh quartz sand, and 800-mesh silica powder with a mass ratio of 2:1:3), 1% auxiliary agent (organically modified flaky silicate BYK1958, BYKA530), and 6% fumed silica (with a particle size of 35 nm);

[0142] Based on the mass of component B being 100%, component B includes 20.2% composite amine curing agent (Versamid140, Ancamine 2014FG, and D.E.H.85 with a mass ratio of 1:1:5), 57% functional filler (50-mesh quartz sand, 400-mesh quartz sand, and 800-mesh silica powder with a mass ratio of 2:1:3), 0.30% coupling agent (KH-560 and KH-550 with a mass ratio of 1:1), 18% nano-aluminum oxide (with a particle size of 40 nm and a specific surface area of 280 m 2 / g), 1.2% 2,4,6-tris(dimethylaminomethyl)phenol, 3.0% glycerol triglycidyl ether, and 0.30% auxiliary agent (organically modified flaky silicate BYK1958, BYKA530).

[0143] A preparation method of an epoxy resin structural adhesive for connecting and sealing high-strength precast pipe piles includes the following steps:

[0144] S1: Preheat epoxy resin and polyurethane modified epoxy resin at a temperature of 55 °C for 20 min to obtain a mixed resin, and the viscosity of the mixed resin is 1000 mPa·s;

[0145] S2: Add an active diluent to the mixed resin, perform the first stirring, then add part of the fumed silica for the second stirring, and further add the filler in 3 batches at intervals of 3 min for the third stirring to obtain a first mixed material;

[0146] Among them, the speed of the first stirring is 150 rpm and the time is 10 min;

[0147] The speed of the second stirring is 1000 rpm, the time is 10 min, and the temperature is 45 °C;

[0148] The speed of the third stirring is 1000 rpm and the time is 15 min;

[0149] The part of the fumed silica added accounts for 50% of the total mass of the fumed silica;

[0150] S3: Pre-mix the coupling agent with the remaining fumed silica to obtain a second mixed material. Atomize and spray the second mixed material into the first mixed material, perform the fourth stirring, and finally perform vacuum defoaming to obtain the A-component material;

[0151] Among them, the stirring speed for pre-mixing is 500 rpm and the time is 10 min;

[0152] The pressure for atomizing and spraying is 0.5 MPa, and the second mixed material is atomized into 50 - 100 μm droplets;

[0153] The fourth stirring speed is 500 rpm and the time is 10 min;

[0154] The vacuum defoaming includes:

[0155] The pressure is -0.01 MPa, the temperature is 45 °C, the time is 25 min, and the bubble volume fraction < 0.5%;

[0156] S4: Stir and heat the composite amine curing agent to 50 °C at a rotation speed of 200 rpm, and then introduce nitrogen to remove water for 30 min to obtain the activated amine curing agent;

[0157] The volume percentage of water in the activated amine curing agent in the total volume of the activated amine curing agent ≤ 0.3%;

[0158] S5: Pre-mix the nano-aluminum oxide and the coupling agent on a ball mill at a mass ratio of 9:1. The ball milling speed is 350 rpm and the ball milling time is 2 h to obtain a third mixed material. Add the third mixed material to the activated amine curing agent in 3 batches, perform the fifth stirring, then add the tertiary amine accelerator, perform the sixth stirring, and finally perform homogenization treatment and vacuum defoaming to obtain the B-component material;

[0159] Among them, the stirring speed for the fifth stirring is 400 rpm and the time is 15 min;

[0160] The stirring speed for the sixth stirring is 100 rpm and the time is 10 min;

[0161] The homogenization treatment means high-speed dispersion at a rotation speed of 1000 rpm for 5 min;

[0162] The vacuum defoaming includes:

[0163] The pressure is -0.05 MPa, the temperature is 45 °C, the time is 15 min, and the bubble volume fraction < 0.5%.

[0164] S6: Mix the A component material and the B component material at a temperature of 35° C. for 10 minutes using a static mixer or a twin-screw continuous mixer to obtain a high-strength epoxy resin structural adhesive for prefabricated pipe pile connection sealing.

[0165] Comparative Example 1

[0166] The main difference between this comparative example and Example 1 is that the mass ratio of component A to component B is 3:1, and the remaining steps and technical parameters are the same as those of Example 1.

[0167] Comparative Example 2

[0168] The main difference between this comparative example and Example 1 is that no silicon powder is added to the filler, and all of it is quartz sand, specifically 50-mesh quartz sand and 400-mesh quartz sand in a mass ratio of 2:1. The remaining steps and technical parameters are the same as those in Example 1.

[0169] Comparative Example 3

[0170] The main difference between this comparative example and Example 1 is that no nano-alumina is added, specifically:

[0171] Taking the mass of component B as 100%, the component B includes 40% of a complex amine curing agent (Versamid140, Ancamine 2014FG and DEH85 in a mass ratio of 1:1:3), 56.5% of a functional filler (50 mesh quartz sand, 400 mesh quartz sand and 800 mesh silicon powder in a mass ratio of 2:1:3), 0.20% of a coupling agent (KH-560 and KH-550 in a mass ratio of 1:1), 1% of 2,4,6-tris(dimethylaminomethyl)phenol, 2.0% of propylene triglycidyl ether, and 0.30% of an additive (organic modified sheet silicate BYK1958, BYKA530).

[0172] Comparative Example 4

[0173] The main difference between this comparative example and Example 1 is that in step S2, all the fumed silica is added at one time, and the remaining steps and technical parameters are the same as those in Example 1.

[0174] Comparative Example 5

[0175] The main difference between this comparative example and Example 1 is that in step S5, the nano-alumina and the coupling agent are not pre-mixed first, but are directly added to the activated amine curing agent for the fifth stirring. The remaining steps and technical parameters are the same as those in Example 1.

[0176] Performance Testing

[0177] Compressive strength: Test standard refers to GB / T 2567-2021;

[0178] Elongation at break: The test standard refers to ASTM D638;

[0179] Thixotropy index: The test standard refers to ISO 3219;

[0180] Anti-sagging property: The test standard refers to ASTM D2202;

[0181] Self-leveling ability: The test standard refers to ISO 13007-1:2020;

[0182] Salt spray test: The test standard refers to ASTM B117-19.

[0183] As an epoxy resin structural adhesive applicable to the connection and sealing of precast pipe piles, its elongation at break should be controlled within 3-5%, and the compressive strength > 80 MPa, the thixotropy index is between 4.5-4.8, and the sagging degree < 1 mm.

[0184] Effect data

[0185] The performance test results of the structural adhesives prepared in the examples and comparative examples are shown in Table 1:

[0186] Table 1

[0187]

[0188] As shown in Table 1, compared with Example 1, in Comparative Example 1, since the mass ratio of Component A and Component B is 3:1, the crosslinking density of the curing network of the epoxy resin structural adhesive for the connection and sealing of high-strength precast pipe piles prepared is smaller than that of Example 1, which affects the mechanical properties of the structural adhesive.

[0189] As shown in Table 1, compared with Example 1, in Comparative Example 2, since silica powder is not added in Comparative Example 2, it cannot produce a synergistic effect with fumed silica, which affects the mechanical properties of the structural adhesive and also affects the salt spray resistance and fluidity of the structural adhesive.

[0190] As shown in Table 1, compared with Example 1, in Comparative Example 3, since nano-aluminum oxide is not added in Comparative Example 3, it not only affects the mechanical properties of the structural adhesive but also significantly reduces its salt spray resistance.

[0191] As shown in Table 1, compared with Example 1, in Comparative Example 4, since all the fumed silica is added at one time in Comparative Example 4, the viscosity of the whole system increases significantly, which affects the bonding strength with the resin, reduces the mechanical properties and salt spray resistance of the structural adhesive, and it is difficult to achieve self-leveling filling.

[0192] As shown in Table 1, compared with Example 1, in Comparative Example 5, since nano-aluminum oxide was not premixed with the coupling agent, agglomeration of nano-aluminum oxide occurred, which not only affected the mechanical properties of the structural adhesive, but also significantly reduced the salt spray resistance and fluidity of the structural adhesive.

[0193] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An epoxy resin structural adhesive for connecting and sealing high-strength precast pipe piles, characterized in that, It includes component A and component B with a mass ratio of (4 - 6):1; Based on the mass of component A being 100%, component A includes 30 - 50% of epoxy resin, 5 - 15% of polyurethane - modified epoxy resin, 0.05 - 0.30% of coupling agent, 3 - 10% of active diluent, 30 - 45% of functional filler, 1 - 5% of additive, and 3 - 6% of fumed silica; Based on the mass of component B being 100%, component B includes 5 - 40% of composite amine curing agent, 40 - 65% of functional filler, 0.05 - 0.30% of coupling agent, 15 - 18% of nano - alumina, 0.8 - 1.2% of tertiary amine accelerator, 0.5 - 3.0% of active diluent, and 0.05 - 0.30% of additive.

2. The epoxy resin structural adhesive for connecting and sealing high-strength precast pipe piles according to claim 1, wherein The epoxy resin includes one or more of bisphenol A - type epoxy resin, hydrogenated bisphenol A - type epoxy resin, and phenolic epoxy resin; And / or, the polyurethane - modified epoxy resin is SL3411 toughened polyurethane - modified epoxy resin; And / or, the additive includes one or more of rheological agent and defoaming agent; And / or, the active diluent includes one or more of dodecyl - tetradecyl glycidyl ether, cardanol glycidyl ether, cyclohexanediol diglycidyl ether, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol tetraglycidyl ether; And / or, the functional filler includes 50 - 100 - mesh quartz sand, 200 - 400 - mesh quartz sand, and 800 - 1000 - mesh silica powder with a mass ratio of (1 - 2):1:(3 - 5); And / or, the particle size of the fumed silica is 7 - 40 nm.

3. The epoxy resin structural adhesive for connection and sealing of high-strength precast pipe piles according to claim 1, wherein The composite amine curing agent includes polyamide - type epoxy resin curing agent, modified aliphatic amine curing agent, and aromatic - modified amine curing agent with a mass ratio of 1:1:(2 - 5); The polyamide curing agent includes one or more of Versamid 140, Ancamide 500 - A, or Aradur 250; The modified aliphatic amine curing agent includes one or more of Ancamine 2014FG, Cardolite NX - 5451, or Aradur 2963; The aromatic - modified amine curing agent includes one or more of D.E.H.85, Epikure 3115, or Aradur 917; And / or, the coupling agent includes at least one of silane coupling agent KH - 560 or silane coupling agent KH - 550; And / or, the tertiary amine accelerator includes one or more of 2,4,6 - tris(dimethylaminomethyl)phenol, benzyldimethylamine, and dimethylaminomethylphenol; And / or, the particle size of the nano-aluminum oxide is 30-50 nm, and the specific surface area > 180 m 2 / g.

4. A preparation method of an epoxy resin structural adhesive for connecting and sealing high-strength precast pipe piles as described in any one of claims 1-3, characterized in that, It includes the following steps: S1: Pre - heat the epoxy resin and polyurethane - modified epoxy resin to obtain a mixed resin; S2: Add the active diluent to the mixed resin, conduct the first stirring, then add part of the fumed silica for the second stirring, and further add the filler for the third stirring to obtain a first mixed material; S3: After premixing the coupling agent with the remaining fumed silica to obtain a second mixed material, spray and add the second mixed material into the first mixed material, perform a fourth stirring, and finally perform vacuum defoaming to obtain the A-component material; S4: Activate the composite amine curing agent to obtain an activated amine curing agent; S5: After premixing the nano-aluminum oxide with the coupling agent to obtain a third mixed material, add the third mixed material into the activated amine curing agent, perform a fifth stirring, then add a tertiary amine accelerator, perform a sixth stirring, and finally perform homogenization treatment and vacuum defoaming to obtain the B-component material; S6: Mix the A-component material and the B-component material to obtain an epoxy resin structural adhesive for connecting and sealing high-strength precast pipe piles.

5. The preparation method of the epoxy resin structural adhesive for high-strength precast pipe pile connection sealing according to claim 4, characterized in that, In step S1, the preheating temperature is 45 - 55 °C, the preheating time is 20 - 35 min, and the viscosity of the mixed resin is 800 - 1000 mPa·s.

6. The preparation method of the epoxy resin structural adhesive for connecting and sealing high-strength precast pipe piles according to claim 4, characterized in that, In step S2, the speed of the first stirring is 150 - 200 rpm, and the time is 5 - 10 min; And / or, in step S2, the proportion of the partial fumed silica added accounts for 40 - 55% of the total mass of the fumed silica; And / or, in step S2, the speed of the second stirring is 1000 - 1200 rpm, the time is 10 - 15 min, and the temperature ≤ 50 °C; And / or, in step S2, the speed of the third stirring is 800 - 1000 rpm, and the time is 10 - 15 min; And / or, in step S2, the filler is added in batches, with an interval of 2 - 3 min each time.

7. The preparation method of the epoxy resin structural adhesive for high-strength precast pipe pile connection sealing according to claim 4, characterized in that, In step S3, the stirring speed of the premixing is 500 - 600 rpm, and the time is 10 - 15 min; And / or, in step S3, the spraying method is atomized spraying, the pressure of the atomized spraying is 0.3 - 0.5 MPa, and the second mixed material is atomized into liquid droplets of 50 - 100 μm; And / or, in step S3, the speed of the fourth stirring is 500 - 600 rpm, and the time is 10 - 15 min; And / or, in step S3, the vacuum defoaming includes: The pressure is -0.03 ~ -0.01 MPa, the temperature is 35 - 45 °C, the time is 20 - 25 min, and the bubble volume fraction < 0.5%.

8. The preparation method of the epoxy resin structural adhesive for high-strength precast pipe pile connection and sealing according to claim 4, characterized in that, In step S4, the activation includes the following steps: Stir and heat the composite amine curing agent at a rotation speed of 150 - 200 rpm to 40 - 50 °C, and then introduce nitrogen to remove water for 30 min to obtain an activated amine curing agent; The volume percentage of water in the activated amine curing agent accounts for ≤ 0.3% of the total volume of the activated amine curing agent.

9. The preparation method of the epoxy resin structural adhesive for high-strength precast pipe pile connection sealing according to claim 4, characterized in that, In step S5, the nano-aluminum oxide and the coupling agent are premixed on a ball mill at a mass ratio of 8 - 10:1, the ball milling rotation speed is 250 - 350 rpm, and the ball milling time is 2 - 2.5 h; And / or, in step S5, the stirring speed of the fifth stirring is 400 - 500 rpm, and the time is 15 - 20 min; And / or, in step S5, the third mixed material is added into the activated amine curing agent in batches, with an interval of 2 - 3 min each time; And / or, in step S5, the stirring speed of the sixth stirring is 100 - 200 rpm, and the time is 10 - 15 min; And / or, in step S5, the homogenization treatment means high-speed dispersion at a rotational speed of 1000 - 1500 rpm for 5 - 10 min; And / or, in step S5, the vacuum degassing includes: The pressure is -0.09 to -0.05 MPa, the temperature is 35 - 45 °C, the time is 10 - 15 min, and the bubble volume fraction < 0.5%.

10. The preparation method of the epoxy resin structural adhesive for high-strength precast pipe pile connection sealing according to claim 4, characterized in that, In step S6, the component A material and the component B material are mixed at a temperature of 10 - 35 °C for 5 - 10 min by using a static mixer or a twin-screw continuous mixer.

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