A structural adhesive for heliostats and its preparation method

Abstract

This application discloses a structural adhesive for heliostats and its preparation method. The structural adhesive comprises component A and component B. Component A consists of the following raw materials: 10-40 parts epoxy resin, 1-10 parts diluent, 1-5 parts epoxy silane coupling agent, 1-5 parts thixotropic agent, 5-20 parts toughening agent, and 10-40 parts filler. Component B consists of the following raw materials: 10-40 parts curing agent, 1-5 parts amino silane coupling agent, 1-5 parts thixotropic agent, 10-40 parts filler, and 1-10 parts curing accelerator. The epoxy resin includes one or a combination of several of E-44 epoxy resin, E-51 epoxy resin, bisphenol F170 epoxy resin, and polyetheramine modified epoxy resin. The structural adhesive system formed by different epoxy resin blends and polythiol curing agents can adapt to the application environment of heliostats, exhibiting good construction performance at low temperatures, maintaining structural stability at high temperatures, and possessing good bulk strength and adhesion.

Description

Technical Field

[0001] This application relates to the field of epoxy resin structural adhesives, and in particular to a structural adhesive for heliostats and its preparation method. Background Technology

[0002] With the development of society and the economy, fossil fuels have been extensively used and are gradually being depleted, leading to increasingly serious environmental pollution problems. The development of new clean energy sources is becoming increasingly urgent, and the country is strongly supporting the development and utilization of new energy. Among these, concentrated solar power (CSP), as a new type of clean energy, combines the advantages of concentrated solar power, heat storage, and heat exchange, and its share in the electricity market is gradually increasing. CSP plants will become a new trend in power plant construction.

[0003] Concentrated solar power (CSP) primarily utilizes thousands of heliostats to project sunlight onto the surface of a receiver located at the top of a solar tower, generating temperatures exceeding 800°C. This heat is then transferred through a heat transfer medium to produce steam exceeding 500°C, which drives a steam turbine to generate electricity, thus achieving CSP generation. The heliostats are a crucial component in CSP. Traditional CSP heliostats are mechanically connected to the backplate using bolts. After prolonged use, this connection method is prone to rusting and breakage, leading to angle shifts in the heliostats and an inability to accurately reflect sunlight onto the receiver surface, resulting in decreased CSP efficiency.

[0004] To address the issue of reduced power generation efficiency due to heliostat misalignment caused by aging and rust at the backplate connection, people began to consider replacing traditional mechanical connection methods with adhesives. However, adhesives have limited strength, poor construction performance in low-temperature environments such as Northwest China, and limited aging resistance, failing to completely solve the problems associated with traditional methods. Therefore, it is of great significance to develop an adhesive with high body strength, good construction performance in low-temperature environments, and excellent aging resistance. Summary of the Invention

[0005] To address the problems of insufficient strength, poor workability at low temperatures, and poor aging resistance of general adhesives, this application provides a structural adhesive for heliostats and its preparation method.

[0006] In a first aspect, this application provides a structural adhesive for heliostats, the structural adhesive comprising component A and component B; component A comprises the following raw materials in parts by weight:

[0007] 10-40 parts epoxy resin;

[0008] 1 to 10 parts of diluent;

[0009] 1-5 parts of epoxy silane coupling agent;

[0010] Thixotropic agent 1-5 parts;

[0011] 5-20 parts toughening agent;

[0012] 10-40 parts of filler;

[0013] Component B comprises the following raw materials in parts by weight:

[0014] 10-40 parts of curing agent;

[0015] 1-5 parts of aminosilane coupling agent;

[0016] Thixotropic agent 1-5 parts;

[0017] 10-40 parts of filler;

[0018] 1-10 parts of curing accelerator;

[0019] The epoxy resin includes one or a combination of several of E-44 epoxy resin, E-51 epoxy resin, bisphenol F170 epoxy resin, and polyetheramine modified epoxy resin.

[0020] Preferably, the mass ratio of component A to component B in the structural adhesive for heliostats is 1:1.

[0021] Preferably, the diluent is a glycidyl ether diluent.

[0022] More preferably, the diluent is one or a combination of two of glycidyl ether diluent XY622 and glycidyl ether diluent XY693.

[0023] Preferably, the epoxy silane coupling agent includes one or a combination of several of γ-glycidyl etheroxypropyltrimethoxysilane, γ-glycidyl etheroxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane, 3-glycidyl etheroxypropyltrimethoxysilane, and 3-glycidyl etheroxypropyltriethoxysilane.

[0024] More preferably, the epoxy silane coupling agent is γ-glycidoxypropyltrimethoxysilane.

[0025] Preferably, the aminosilane coupling agent includes one or a combination of several of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, and 3-(2-aminoethylamino)propyltrimethoxysilane.

[0026] More preferably, the aminosilane coupling agent is γ-aminopropyltriethoxysilane.

[0027] Preferably, the thixotropic agent includes one or a combination of several of the following: thixotropic agent TS-720, thixotropic agent M5, and thixotropic agent R202.

[0028] By adopting the above technical solution, this application is a two-component epoxy resin structural adhesive. The curing time can be flexibly controlled by mixing the two components in a certain ratio, which is beneficial to maintaining the activity of the raw materials and is suitable for curing processes in various environments. Compared with single-component structural adhesives, which rely on certain ambient temperature and humidity, the two-component structural adhesive of this application can also initiate the curing reaction in low-temperature environments.

[0029] Furthermore, epoxy silane coupling agent and amino silane coupling agent are added to components A and B, respectively. The addition of silane coupling agent is beneficial to improving the adhesion performance between the structural adhesive and the heliostat, enhancing the bonding force at the adhesive interface, and can also participate in the curing process of epoxy resin, improving the stability of the epoxy resin curing network, which is beneficial to improving the crosslinking density of the epoxy resin structural adhesive after curing. This reduces the transmittance of moisture or gas during use, thereby slowing down the aging process caused by ultraviolet light irradiation, temperature changes, and chemical corrosion, and enhancing the weather resistance of the structural adhesive.

[0030] Meanwhile, the epoxy resin used in this application is one or a combination of several of E-44 epoxy resin, E-51 epoxy resin, bisphenol F170 epoxy resin, and polyetheramine modified epoxy resin. Among them, bisphenol A type epoxy resin can form a tight three-dimensional cross-linked structure after curing, which has excellent adhesion and peel resistance, as well as certain electrical insulation. The viscosity of bisphenol F170 epoxy resin is lower than that of E-44 epoxy resin and E-51 epoxy resin, which can better control the viscosity of the system and is suitable for use in different environments and on substrates of different shapes. Polyetheramine modified epoxy resin has good low-temperature performance and does not affect construction and use under cold conditions. In addition, polyamide modified epoxy resin can also increase the overall flexibility and improve the problem of high brittleness of epoxy resin structural adhesive after curing. Combining the above different types of epoxy resin can make up for their respective performance defects and obtain a more functional epoxy resin mixture. In the synergistic system, other additives can obtain epoxy resin structural adhesives with excellent strength, good weather resistance, and good construction performance at low temperatures.

[0031] Preferably, the epoxy resin is a mixture of E-51 epoxy resin, E-44 epoxy resin, bisphenol F170 epoxy resin and polyetheramine modified epoxy resin in a mass ratio of (2-4):(1-2):(1-2):1.

[0032] By adopting the above technical solution, this application uses E-51 epoxy resin as the base component of the epoxy resin. E-51 epoxy resin has a high epoxy value, which provides a large number of crosslinking points during the curing reaction, ensuring the subsequent crosslinking and curing process, thereby increasing the crosslinking density of the structural adhesive after curing and resulting in higher interfacial bonding strength with the substrate. E-44 epoxy resin and E-51 epoxy resin are both bisphenol A type epoxy resins. Mixing them can adjust the viscosity of the epoxy resin, facilitating construction and molding, and better maintaining the position and shape of the bonded components without affecting the heliostat's transmission of sunlight.

[0033] Meanwhile, at low temperatures, the molecular chain movement of epoxy resin slows down, which is conducive to the formation of a crystal structure in epoxy resin and affects the performance of structural adhesives. Due to the differences in molecular structure and chain segment length between E-44 epoxy resin and E-51 epoxy resin, the uneven molecular structure and chain segments after mixing will interfere with the ordered arrangement required for crystallization, thereby reducing the possibility of epoxy resin crystallization.

[0034] The addition of bisphenol F170 epoxy resin and polyetheramine-modified epoxy resin can improve the overall stability and low-temperature construction performance, and enhance the functionality of epoxy resin. Among them, bisphenol F170 epoxy resin contains phenol groups and ether bonds, which gives it high intermolecular forces, higher chemical stability, and resistance to chemical reagent attack. When combined with E-51 epoxy resin, it forms a more compact cross-linked network structure, which can effectively improve the molecular chain entanglement and structural adhesive softening and deformation caused by temperature rise, and improve the structural stability and dimensional stability of the structural adhesive. On the other hand, polyetheramine-modified epoxy resin contains long flexible segments. Introducing it into the cross-linked network structure of epoxy resin can significantly improve the toughness of the cured product, and it can also have good construction performance and curing speed in low-temperature environments.

[0035] By combining these four epoxy resins in the correct proportions and to complement each other's properties, the resulting epoxy resin is adapted to the application environment of heliostats. It exhibits good workability at low temperatures, maintains structural stability at high temperatures, has good aging resistance, and possesses high bulk strength and adhesive properties, fully meeting the requirements for bonding heliostats.

[0036] Preferably, the curing agent is a polythiol curing agent or a combination of a polythiol curing agent and a phenolic amine curing agent.

[0037] By adopting the above technical solution, the molecular chain of the polythiol curing agent contains two or more thiol groups. The thiol groups have high activity and can react rapidly with the epoxy groups in the epoxy resin. The activation energy required for the reaction is low. Compared with amine and acid anhydride curing agents, it has higher reactivity and can maintain a fast reaction rate even at low temperatures, thus accelerating the reaction process. It is suitable for heliostat applications.

[0038] When polythiol curing agents are used in combination with phenolic amine curing agents, the curing speed can be accelerated to a certain extent. Specifically, the active thiol groups in polythiol curing agents react with epoxy groups to promote the rapid initial curing of epoxy resin at low temperatures. Meanwhile, the reaction between the amino groups and epoxy groups in phenolic amine curing agents is more stable, which helps to promote the stability of the cross-linked structure in the cured system, thereby improving the mechanical properties and thermal stability of the final cured structural adhesive.

[0039] Furthermore, the sulfur-containing flexible segments in the polythiol curing agent can further improve the toughness of the resin, effectively preventing the extreme brittleness and poor impact resistance of the cured epoxy resin at low temperatures. This effectively avoids the severe impact on the construction performance of the epoxy resin and the performance of the structural adhesive itself at low temperatures.

[0040] Preferably, the polythiol curing agent is a modified polythiol curing agent; the raw materials of the modified polythiol curing agent include polythiol curing agent and isophorone diisocyanate in a mass ratio of 1:(0.05-0.1).

[0041] By adopting the above technical solution, although the polythiol curing agent can still provide reactive groups for epoxy resin under low temperature conditions, accelerate the curing efficiency at low temperatures, and solve the problem of rapid curing at low temperatures, the functional groups contained in the polythiol curing agent are highly active and easily oxidized or react with other substances, resulting in poor curing agent stability. At the same time, the molecular weight of the polythiol curing agent is also small, resulting in poor dispersibility in the system. Therefore, in order to improve the stability of the system at room temperature, the polythiol curing agent is modified. Specifically, the polythiol curing agent is modified by isophorone diisocyanate.

[0042] The introduction of a small amount of isophorone diisocyanate allows its isocyanate groups to react with the active groups in the polythiol curing agent, forming a stable esterified structure. This new functional group alters the chemical properties of the polythiol curing agent molecule, making it less prone to oxidation and improving its stability at room temperature. The unique cyclic structure of isophorone diisocyanate provides high rigidity, further enhancing the curing agent's stability. Furthermore, during the curing process of epoxy resin, the modified polythiol curing agent provides more crosslinking points, forming a denser crosslinking network, thereby improving the structural adhesive's strength, heat resistance, and aging resistance. Simultaneously, the flexibility and dynamic crosslinking characteristics of isophorone diisocyanate also enhance the toughness and low-temperature performance of the cured epoxy resin.

[0043] Preferably, the modified polythiol curing agent is prepared by the following method: adding a catalyst to the polythiol curing agent and mixing it evenly, then raising the temperature to 60-70°C, adding isophorone diisocyanate dropwise, and stirring the reaction for 5-6 hours to obtain the modified polythiol curing agent.

[0044] Preferably, the catalyst includes one of stannous octoate, dibutyltin dilaurate, and triethylamine.

[0045] By adopting the above technical solution, under the action of a catalyst, the isocyanate groups in isophorone diisocyanate can react with the mercapto groups to form a stable ester structure, thereby improving the stability of the polythiol curing agent.

[0046] Preferably, the toughening agent is a toughening agent called Qishi toughening agent.

[0047] By adopting the above technical solution, Qishi toughening agent is a polymer mixture toughening agent with different active end groups and different types of chain segments linked together by ester bonds and amino bonds. It can aggregate into spherical particles during the curing process of epoxy resin, and then become dispersed in the continuous phase composed of the cross-linked network structure of epoxy resin. The formation of this "island structure" will significantly improve the ability of epoxy resin matrix to yield and plastically deform, thereby greatly improving the toughness of epoxy resin matrix and improving the low temperature performance of epoxy resin.

[0048] Preferably, the filler comprises one or a combination of several of the following: silicon micropowder, calcium carbonate, and hollow glass microspheres.

[0049] By adopting the above technical solution, in order to further improve the strength and thermal stability of the structural adhesive, fillers such as silica powder, calcium carbonate, and hollow glass microspheres are added to each component to improve the mechanical properties of the structural adhesive. In addition, the addition of fillers can also reduce volume shrinkage during the curing process and improve the construction performance of the structural adhesive.

[0050] Preferably, the filler is further modified with a titanate coupling agent; the titanate coupling agent is a composition of triisostearate isopropyl titanate and bis(dioctylpyrophosphoryloxy)ethylene titanate in a mass ratio of 1:(0.45-0.6).

[0051] By adopting the above technical solution, the filler's small particle size results in poor dispersibility and weak bonding with epoxy resin, limiting its ability to improve the performance of the structural adhesive. Therefore, a titanate coupling agent is used to modify the filler. Specifically, a composition of triisostearate titanate isopropyl titanate and bis(dioctylpyrophosphoryloxy)ethylene titanate is used to modify the filler. The isopropoxy group in triisostearate titanate reacts with the polar groups on the filler surface, while the isostearic acid group at the other end forms intermolecular forces or chemical bonds with the epoxy resin, thereby improving the filler's dispersibility and bonding strength in the epoxy resin, reducing filler agglomeration, and improving its compatibility in the system.

[0052] Besides improving filler compatibility to some extent, bis(dioctylpyrophosphate)ethylene titanate contains pyrophosphate groups that exhibit good stability at low temperatures. Furthermore, its relatively long alkyl chains contribute to molecular fluidity at low temperatures, thus promoting bonding between the filler and epoxy resin while effectively improving low-temperature performance. It also prevents crystallization during curing, thereby not affecting the performance of the structural adhesive. The combination of these two materials can improve filler compatibility and dispersibility while enhancing the system's low-temperature resistance without compromising the filler's effect on epoxy resin performance.

[0053] Preferably, the curing accelerator is a tertiary amine curing accelerator.

[0054] By adopting the above technical solution, the tertiary amine in the tertiary amine curing accelerator can act as a catalyst, improving the completion of the curing reaction and effectively reducing the activation energy of the reaction. This promotes rapid curing even at low temperatures, shortening the curing time and improving the low-temperature application performance and construction efficiency of the structural adhesive. Furthermore, the addition of the accelerator can further promote the formation of a cross-linked network structure in the epoxy resin system, increasing the strength of the structural adhesive.

[0055] Secondly, this application also provides a method for preparing structural adhesive for heliostats, comprising the following process steps:

[0056] Preparation of Component A: Weigh the corresponding mass parts of epoxy resin, diluent, epoxy silane coupling agent and toughening agent, mix them evenly, add filler, mix evenly again, add thixotropic agent, and finally mix evenly to obtain Component A.

[0057] Preparation of Component B: Weigh out the corresponding mass fractions of curing agent, curing accelerator and aminosilane coupling agent, mix them evenly, add filler, mix them evenly again, add thixotropic agent, and finally mix them evenly to obtain Component B.

[0058] In summary, this application has the following beneficial effects:

[0059] 1. The structural adhesive for heliostats in this application is a two-component epoxy resin structural adhesive, wherein the epoxy resin is a mixture of E-51 epoxy resin, E-44 epoxy resin, bisphenol F170 epoxy resin and polyetheramine modified epoxy resin. Based on E-51 epoxy resin, E-44 epoxy resin can adjust the resin viscosity, reduce the probability of crystallization, and facilitate construction and molding. The addition of bisphenol F170 epoxy resin and polyetheramine modified epoxy resin can improve the overall stability and low-temperature construction performance. The four epoxy resins work together to make the final epoxy resin adaptable to the application environment of heliostats, with good construction performance at low temperatures and structural stability at high temperatures. At the same time, it also has good thermal stability, aging resistance, bulk strength and adhesion.

[0060] 2. The curing agent used in this application is a polythiol curing agent, which contains highly reactive functional groups and maintains a relatively fast reaction rate even at low temperatures, thereby improving the curing speed of epoxy resin at low temperatures. Furthermore, to improve the stability of the polythiol curing agent, it is modified. The introduction of isophorone diisocyanate can improve the stability of the curing agent molecules at room temperature and provide more crosslinking points for the epoxy resin curing process, thereby improving the strength, heat resistance, and aging resistance of the structural adhesive.

[0061] 3. The filler used in this application has also undergone modification with a titanate coupling agent. Specifically, the titanate coupling agent is a combination of triisostearate titanate isopropyl titanate and bis(dioctylpyrophosphate)ethylene titanate. The former mainly plays a role in improving compatibility, while the latter, based on the former, introduces pyrophosphate groups with high low-temperature stability and long-chain alkyl groups, which can effectively improve low-temperature resistance. This will not affect the filler's improvement of epoxy resin properties. Detailed Implementation

[0062] Preparation example of modified polythiol curing agent

[0063] Preparation Example 1-1: A modified polythiol curing agent was prepared according to the following method:

[0064] Take 10g of polythiol curing agent (model HM800), add 0.2g of dibutyltin dilaurate and mix well. Then raise the temperature to 65℃, add 0.8g of isophorone diisocyanate, and stir for 6h to obtain the modified polythiol curing agent.

[0065] Preparation Example 1-2, a modified polythiol curing agent, differs from Preparation Example 1-1 only in that the amount of isophorone diisocyanate added is 0.5g.

[0066] Preparation Examples 1-3, a modified polythiol curing agent, differs from Preparation Example 1-1 only in that the amount of isophorone diisocyanate added is 1g.

[0067] Preparation Examples 1-4, a modified polythiol curing agent, differs from Preparation Example 1-1 only in that the amount of isophorone diisocyanate added is 0.2g.

[0068] Preparation Examples 1-5, a modified polythiol curing agent, differs from Preparation Example 1-1 only in that the amount of isophorone diisocyanate added is 1.5g.

[0069] Preparation example of titanate coupling agent modified filler

[0070] Preparation Example 2-1: A titanate coupling agent modified silica powder was prepared according to the following method:

[0071] Add 3g of titanate coupling agent to 200ml of toluene, then add 4g of water dropwise, stir and dissolve to obtain a premix; add 100g of silica powder (particle size 400 mesh) to the premix, stir and react at 70℃ for 5h, then wash and dry to obtain titanate coupling agent modified filler.

[0072] The titanate coupling agent is a composition of triisostearate isopropyl titanate and bis(dioctylpyrophosphoryloxy)ethylene titanate in a mass ratio of 1:0.5.

[0073] Preparation Example 2-2: A titanate coupling agent modified calcium carbonate was prepared according to the following method:

[0074] Add 3g of titanate coupling agent to 200ml of toluene, then add 4g of water dropwise, stir to dissolve and obtain a premix; add 100g of calcium carbonate (particle size 5-10μm) to the premix, stir and react at 70℃ for 5h, then wash and dry to obtain titanate coupling agent modified filler.

[0075] The titanate coupling agent is a composition of triisostearate isopropyl titanate and bis(dioctylpyrophosphoryloxy)ethylene titanate in a mass ratio of 1:0.5.

[0076] Preparation Examples 2-3: Hollow glass microspheres modified with a titanate coupling agent were prepared according to the following method:

[0077] Add 3g of titanate coupling agent to 200ml of toluene, then add 4g of water dropwise, stir to dissolve and obtain a premix; add 100g of hollow glass microspheres (particle size 30-40μm) to the premix, stir and react at 70℃ for 5h, then wash and dry to obtain titanate coupling agent modified filler.

[0078] The titanate coupling agent is a composition of triisostearate isopropyl titanate and bis(dioctylpyrophosphoryloxy)ethylene titanate in a mass ratio of 1:0.5.

[0079] Preparation Example 2-4: A titanate coupling agent modified silica powder, which differs from Preparation Example 2-1 only in that a titanate coupling agent obtained by combining triisostearate isopropyl titanate and bis(dioctylpyrophosphoryloxy)ethylene titanate in an equal mass ratio of 1:0.45 is used instead of the titanate coupling agent obtained by combining triisostearate isopropyl titanate and bis(dioctylpyrophosphoryloxy)ethylene titanate in a mass ratio of 1:0.5.

[0080] Preparation Example 2-5: A titanate coupling agent modified silica powder, which differs from Preparation Example 2-1 only in that a titanate coupling agent obtained by combining triisostearate isopropyl titanate and bis(dioctylpyrophosphoryloxy)ethylene titanate in an equal mass ratio of 1:0.6 is used instead of the titanate coupling agent obtained by combining triisostearate isopropyl titanate and bis(dioctylpyrophosphoryloxy)ethylene titanate in a mass ratio of 1:0.5.

[0081] Preparation Examples 2-6: A titanate coupling agent modified silica powder, differing from Preparation Example 2-1 only in that a titanate coupling agent obtained by combining triisostearate isopropyl titanate and bis(dioctylpyrophosphoryloxy)ethylene titanate in an equal mass ratio of 1:0.35 is used instead of the titanate coupling agent obtained by combining triisostearate isopropyl titanate and bis(dioctylpyrophosphoryloxy)ethylene titanate in a mass ratio of 1:0.5.

[0082] Preparation Example 2-7: A titanate coupling agent modified silica powder, which differs from Preparation Example 2-1 only in that a titanate coupling agent obtained by combining triisostearate isopropyl titanate and bis(dioctylpyrophosphoryloxy)ethylene titanate in an equal mass ratio of 1:0.7 is used instead of the titanate coupling agent obtained by combining triisostearate isopropyl titanate and bis(dioctylpyrophosphoryloxy)ethylene titanate in a mass ratio of 1:0.5.

[0083] Preparation Examples 2-8: A titanate coupling agent modified silica powder, which differs from Preparation Example 2-1 only in that an equal amount of triisostearate isopropyl titanate is used to replace the titanate coupling agent obtained by combining triisostearate isopropyl titanate and bis(dioctylpyrophosphoryloxy)ethylene titanate in a mass ratio of 1:0.5.

[0084] Preparation Example 2-9: A titanate coupling agent modified silica powder, which differs from Preparation Example 2-1 only in that an equal amount of bis(dioctylpyrophosphoryloxy)ethylene titanate is used to replace the titanate coupling agent obtained by the combination of triisostearate titanate and bis(dioctylpyrophosphoryloxy)ethylene titanate in a mass ratio of 1:0.5.

[0085] Preparation example of polyetheramine modified epoxy resin

[0086] Preparation Example 3-1: A polyetheramine-modified epoxy resin was prepared according to the following method:

[0087] Add 150g of polyetheramine (average molecular weight 1000) and 1.5g of propylene glycol methyl ether acetate to 80g of epoxy resin, raise the temperature to 80℃, keep it at that temperature for 30min, then raise the temperature to 120℃ and stir for 5h. Then lower the temperature to 60℃ to obtain the pre-reactant.

[0088] 20g of epoxy resin and 0.5g of propylene glycol methyl ether acetate were added to the obtained pre-reactant and mixed. The temperature was raised to 100℃ and stirred for 1 hour. The mixture was then filtered to obtain polyetheramine modified epoxy resin.

[0089] The epoxy resins are epoxy resin 901 and epoxy resin 631 with a mass ratio of 2:3 (epoxy equivalent of 460-480).

[0090] Example

[0091] Example 1: A structural adhesive for heliostats, prepared according to the following method:

[0092] Preparation of Component A: Weigh 300g epoxy resin, 40g glycidyl ether diluent XY622, 20g γ-glycidyl etheroxypropyltrimethoxysilane and 20g Qishi toughening agent, mix them evenly, add 250g filler, mix them evenly again, add 30g thixotropic agent TS-720, and finally mix them evenly to obtain Component A.

[0093] Preparation of Component B: Weigh 250g of polythiol curing agent (model HM800), 30g of tertiary amine curing accelerator K54 and 20g of γ-aminopropyltriethoxysilane, mix them evenly, add 30g of filler, mix them evenly again, add 20g of thixotropic agent TS-720, and finally mix them evenly to obtain Component B.

[0094] The epoxy resin is a composition of E-51 epoxy resin (epoxy equivalent of 0.48 to 0.54), E-44 epoxy resin (epoxy equivalent of 0.41 to 0.47), bisphenol F170 epoxy resin (viscosity of 2000 to 5000) and the polyetheramine modified epoxy resin prepared in Preparation Example 3-1, in a mass ratio of 3:1:1:1:1.

[0095] The filler is a combination of silica powder (400 mesh), calcium carbonate (5-10 μm), and hollow glass microspheres (30-40 μm) in a mass ratio of 2:2:1.

[0096] When using, the mass ratio of component A to component B is 1:1.

[0097] Examples 2 to 7 describe a structural adhesive for heliostats, differing from Example 1 only in the adjustment of the proportions of raw materials used in components A and B, as shown in Tables 1 and 2.

[0098] Table 1. Formulation Tables for Examples 1 to 7

[0099]

[0100]

[0101] Table 2. Raw material mass ratio distribution of packings in Examples 1 to 7

[0102]

[0103] In Examples 2 to 7, the epoxy resins used were all compositions of E-51 epoxy resin (epoxy equivalent of 0.48 to 0.54), E-44 epoxy resin (epoxy equivalent of 0.41 to 0.47), bisphenol F170 epoxy resin (viscosity of 2000 to 5000), and the polyetheramine modified epoxy resin prepared in Example 3-1, with a mass ratio of 3:1:1:1:1.

[0104] Examples 8 to 12 describe a structural adhesive for heliostats, differing from Example 1 only in the adjustment of the raw material composition of the epoxy resin used, as shown in Table 3.

[0105] Table 3. Raw material mass ratio distribution of epoxy resin in Examples 1, 8 to 12.

[0106]

[0107] Example 13, a structural adhesive for heliostats, differs from Example 1 only in that the polythiol curing agent is replaced with a curing agent obtained by mixing polythiol curing agent and phenolic amine curing agent (model T-31) in an equal mass ratio of 2:1.

[0108] Example 14, a structural adhesive for heliostats, differs from Example 1 only in that an equal amount of the modified polythiol curing agent prepared in Preparation Example 1-1 is used instead of the polythiol curing agent.

[0109] Example 15, a structural adhesive for heliostats, differs from Example 1 only in that an equal amount of the modified polythiol curing agent prepared in Examples 1-2 is used instead of the polythiol curing agent.

[0110] Example 16, a structural adhesive for heliostats, differs from Example 1 only in that an equal amount of the modified polythiol curing agent prepared in Examples 1-3 is used instead of the polythiol curing agent.

[0111] Example 17, a structural adhesive for heliostats, differs from Example 1 only in that an equal amount of the modified polythiol curing agent prepared in Examples 1-4 is used instead of the polythiol curing agent.

[0112] Example 18, a structural adhesive for heliostats, differs from Example 1 only in that an equal amount of the modified polythiol curing agent prepared in Examples 1-5 is used instead of the polythiol curing agent.

[0113] Example 19, a structural adhesive for heliostats, differs from Example 14 only in that a filler obtained by mixing silicon micropowder prepared in Preparation Example 2-1, calcium carbonate prepared in Preparation Example 2-2, and hollow glass microspheres prepared in Preparation Example 2-3 in equal mass ratios of 2:2:1 is used instead of the filler obtained by mixing silicon micropowder, calcium carbonate, and hollow glass microspheres in a mass ratio of 2:2:1.

[0114] Example 20, a structural adhesive for heliostats, differs from Example 14 only in that an equal amount of silicon micropowder prepared in Preparation Example 2-1 is used to replace the filler obtained by mixing silicon micropowder, calcium carbonate and hollow glass microspheres in a mass ratio of 2:2:1.

[0115] Example 21, a structural adhesive for heliostats, differs from Example 20 only in that an equal amount of silicon micropowder prepared in Preparation Examples 2-4 is used to replace the silicon micropowder prepared in Preparation Example 2-1.

[0116] Example 22, a structural adhesive for heliostats, differs from Example 20 only in that an equal amount of silicon micropowder prepared in Preparation Examples 2-5 is used to replace the silicon micropowder prepared in Preparation Example 2-1.

[0117] Example 23, a structural adhesive for heliostats, differs from Example 20 only in that an equal amount of silicon micropowder prepared in Preparation Examples 2-6 is used to replace the silicon micropowder prepared in Preparation Example 2-1.

[0118] Example 24, a structural adhesive for heliostats, differs from Example 20 only in that an equal amount of silicon micropowder prepared in Preparation Examples 2-7 is used to replace the silicon micropowder prepared in Preparation Example 2-1.

[0119] Example 25, a structural adhesive for heliostats, differs from Example 20 only in that an equal amount of silicon micropowder prepared in Preparation Examples 2-8 is used to replace the silicon micropowder prepared in Preparation Example 2-1.

[0120] Example 26, a structural adhesive for heliostats, differs from Example 20 only in that an equal amount of silicon micropowder prepared in Preparation Examples 2-9 is used to replace the silicon micropowder prepared in Preparation Example 2-1.

[0121] Comparative Example

[0122] Comparative Example 1 is a structural adhesive for heliostats, which differs from Example 1 only in that an equal amount of amine curing agent (amine-105 curing agent) is used instead of polythiol curing agent.

[0123] Comparative Example 2, a structural adhesive for heliostats, differs from Example 1 only in that the amount of polythiol curing agent added is 50g.

[0124] Comparative Example 3, a structural adhesive for heliostats, differs from Example 1 only in that the amount of polythiol curing agent added is 450g.

[0125] Comparative Example 4, a structural adhesive for heliostats, differs from Example 1 only in that γ-glycidoxypropyltrimethoxysilane is not added to component A, and γ-aminopropyltriethoxysilane is not added to component B.

[0126] Comparative Example 5, a structural adhesive for heliostats, differs from Example 1 only in that an equal amount of terminal carboxyl-terminated butadiene-acrylonitrile rubber toughening agent (average number-average molecular weight of 8000) is used instead of the Kies toughening agent.

[0127] Performance testing

[0128] 1. Body strength performance test:

[0129] (1) The tensile strength and elongation at break of the structural adhesives obtained in the examples and comparative examples were tested according to the relevant records in GB / T 2567-2021 "Test Methods for Performance of Resin Castings".

[0130] (2) The tensile shear strength of the structural adhesives obtained in the examples and comparative examples was tested according to the relevant records in GB / T 7124-2008 "Determination of tensile shear strength of adhesives (rigid material to rigid material)".

[0131] 2. Low-temperature performance test: According to the relevant records in GB / T 7124-2008 "Determination of tensile shear strength of adhesives (rigid material to rigid material)", the structural adhesive samples obtained in the examples and comparative examples were kept at 10°C for 15 min, and then the tensile shear strength of the samples was immediately tested.

[0132] 3. Aging resistance test: The structural adhesive samples obtained in the examples and comparative examples were subjected to UV aging for 30 days, freeze-thaw cycles for 50 times, and thermal shock for 1000 hours, respectively. The elongation at break and tensile shear modulus of the samples were tested, and the performance changes before and after the treatment were compared.

[0133] The results of the above experiments are shown in Tables 4 and 5:

[0134] Table 4. Results of Tensile Strength and Elongation at Break Tests

[0135]

[0136]

[0137] Table 5. Tensile Shear Strength Test Results

[0138]

[0139]

[0140] Based on Tables 4 and 5, and in conjunction with Examples 1, 2 through 7, it can be seen that the tensile strength, elongation at break before and after aging, low-temperature performance, and tensile shear strength before and after aging in Examples 2 through 7 are not significantly different from those in Example 1. This indicates that the bulk strength, low-temperature resistance, and aging resistance of Examples 2 through 7 are not significantly different from those in Example 1. This may be because Examples 2 through 7 only adjusted the raw material ratios within the required range compared to Example 1.

[0141] Based on Examples 1 and 8-12, it can be seen that the tensile strength, elongation at break before and after aging, low temperature resistance, and tensile shear strength before and after aging of Examples 8-12 are not significantly different from those of Example 1. However, the performance changes of Examples 11 and 12 are slightly larger. This may be because Examples 8-12 mainly involve changes to the raw material composition of epoxy resin. Example 11 did not add polyetheramine-modified epoxy resin, and Example 12 only used E-51 epoxy resin, which has a significant impact on the workability of the structural adhesive at low temperatures. The lack of application of different types of epoxy resin also has a certain impact on the stability and other properties of the obtained epoxy resin structural adhesive.

[0142] Combining Examples 1 and 13, it can be seen that the tensile strength, elongation at break before and after aging, low-temperature performance, and tensile shear strength before and after aging of Example 13 are slightly higher than those of Example 1, indicating that the bulk strength, low-temperature resistance, and aging resistance of Example 13 are slightly improved compared to Example 1. This may be because the curing agent in Example 13 is a combination of polythiol curing agent and phenolic amine curing agent, which can enhance the crosslinking density during the epoxy resin curing process, thereby improving the aging resistance to a certain extent.

[0143] Combining Examples 1, 14, and 15-18, it can be seen that Example 14 shows improved tensile strength, elongation at break before and after aging, low-temperature performance, and tensile shear strength before and after aging compared to Example 1. This indicates that the bulk strength, low-temperature resistance, and aging resistance of Example 14 are improved compared to Example 1, while the performance of Examples 15-18 is lower than that of Example 14. This may be because the polythiol curing agent in Example 14 underwent modification treatment, which improved the stability of the curing agent and provided more crosslinking points for the curing process, thereby improving the structural adhesive's inherent strength, heat resistance, and aging resistance.

[0144] Based on Examples 14 and 19-26, it can be seen that the tensile strength, elongation at break before and after aging, low-temperature performance, and tensile shear strength before and after aging of Examples 19 and 20 are improved compared to Example 14. This indicates that the bulk strength, low-temperature resistance, and aging resistance of Examples 19 and 20 are improved compared to Example 14. Examples 21-26 show a decrease compared to Example 20, with Example 26 showing a more significant performance decline after low-temperature treatment. This may be because the fillers used in Examples 19 and 20 are modified with titanate coupling agents, which improves the dispersibility and binding force of the fillers in the epoxy resin and enhances the bonding force with the substrate. Furthermore, based on Example 26, it can be seen that the use of bis(dioctylpyrophosphate)ethylene titanate can improve the overall low-temperature performance and prevent crystallization during curing, thus contributing to improved overall performance.

[0145] Based on Examples 1 and Comparative Examples 1 to 5, it can be seen that the tensile strength, elongation at break before and after aging, low-temperature performance, and tensile shear strength before and after aging of Comparative Examples 1 to 5 are all lower than those of Example 1. This indicates that the bulk strength, low-temperature resistance, and aging resistance of Comparative Examples 1 to 5 are lower than those of Example 1, with the most significant decreases in Comparative Examples 1 and 5. The reason for this may be that in Comparative Example 1, an amine curing agent was used instead of a polythiol curing agent. The reactivity of the amine curing agent is lower than that of the polythiol curing agent, resulting in a significant decrease in the low-temperature resistance of the formed structural adhesive and a decrease in the stability of the crosslinking structure, leading to a significant decrease in overall performance. In Comparative Example 5, a general toughening agent was used instead of the Kiesl toughening agent, which cannot form an island structure in the epoxy resin system, resulting in a significant decrease in the improvement of the epoxy resin's toughness and ultimately a decrease in performance.

[0146] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A structural adhesive for heliostats, characterized in that, The structural adhesive comprises component A and component B; component A comprises the following raw materials in parts by weight: 10-40 parts epoxy resin; 1 to 10 parts of diluent; 1-5 parts of epoxy silane coupling agent; Thixotropic agent 1-5 parts; 5-20 parts toughening agent; 10-40 parts of filler; Component B comprises the following raw materials in parts by weight: 10-40 parts of curing agent; 1-5 parts of aminosilane coupling agent; Thixotropic agent 1-5 parts; 10-40 parts of filler; 1-10 parts of curing accelerator; The epoxy resin is a mixture of E-51 epoxy resin, E-44 epoxy resin, bisphenol F170 epoxy resin and polyetheramine modified epoxy resin in a mass ratio of (2-4):(1-2):(1-2):

1. The toughening agent mentioned is Qishi toughening agent.

2. The structural adhesive for heliostats according to claim 1, characterized in that, The curing agent is a polythiol curing agent or a combination of a polythiol curing agent and a phenolic amine curing agent.

3. The structural adhesive for heliostats according to claim 2, characterized in that, The polythiol curing agent is a modified polythiol curing agent; the raw materials of the modified polythiol curing agent include polythiol curing agent and isophorone diisocyanate in a mass ratio of 1:(0.05~0.1).

4. The structural adhesive for heliostats according to claim 3, characterized in that, The modified polythiol curing agent is prepared by the following method: a catalyst is added to the polythiol curing agent and mixed evenly, then the temperature is raised to 60-70°C, isophorone diisocyanate is added dropwise, and the mixture is stirred for 5-6 hours to obtain the modified polythiol curing agent.

5. The structural adhesive for heliostats according to claim 1, characterized in that, The filler includes one or a combination of several of the following: silicon micropowder, calcium carbonate, and hollow glass microspheres.

6. The structural adhesive for heliostats according to claim 5, characterized in that, The filler is also modified with a titanate coupling agent; the titanate coupling agent is a composition of triisostearate isopropyl titanate and bis(dioctyl pyrophosphate) ethylene titanate in a mass ratio of 1:(0.45-0.6).

7. The structural adhesive for heliostats according to claim 1, characterized in that, The curing accelerator is a tertiary amine curing accelerator.

8. The method for preparing the structural adhesive for heliostats according to any one of claims 1 to 7, characterized in that, The following process steps are included in the preparation: Preparation of Component A: Weigh the corresponding mass parts of epoxy resin, diluent, epoxy silane coupling agent and toughening agent, mix them evenly, add filler, mix evenly again, add thixotropic agent, and finally mix evenly to obtain Component A. Preparation of Component B: Weigh out the corresponding mass fractions of curing agent, curing accelerator and aminosilane coupling agent, mix them evenly, add filler, mix them evenly again, add thixotropic agent, and finally mix them evenly to obtain Component B.

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