A biomass underwater curing agent, epoxy composition and preparation method thereof

Abstract

The application discloses a biomass underwater curing agent, an epoxy composition and a preparation method thereof. The epoxy composition comprises two components A and B. The component A comprises 65-85 parts of epoxy resin, 10-15 parts of active diluent, 1-5 parts of toughening agent, 2-8 parts of coupling agent, 0.1-0.5 parts of defoaming agent, 1-3 parts of wetting dispersant, 0.5-1 parts of leveling agent, 20-40 parts of fiber, 150-300 parts of filler, 5-7 parts of anti-settling agent and 0-0.5 parts of coloring pigment. The component B comprises 97-100 parts of underwater curing agent and 1-3 parts of curing accelerator. The composition has good flowability and leveling property, can seal various gaps with a width of not less than 1mm by pressure grouting, and even does not need to be pressurized for filling large gap cavities or holes with a size of more than 5mm by using a self-weight method or a high-position funnel method. During underwater operation, the composition can drive and discharge water near a substrate to be treated due to excellent hydrophobicity, so that the composition can be effectively attached and firmly bonded.

Description

Technical Field

[0001] This invention relates to the field of adhesives, and in particular to a biomass underwater curing agent, an epoxy composition, and a method for preparing the same. Background Technology

[0002] Epoxy adhesives, due to their excellent chemical resistance, high adhesion, and low shrinkage, have a very broad application prospect in structural repair and engineering reinforcement. Generally speaking, the performance of an adhesive largely depends on the curing agent. Commonly available amine curing agents allow epoxy resins to quickly solidify at room temperature, but they are generally only suitable for use in a dry state. If moisture is present at the bonding interface, it will directly affect the bonding effect. In fact, most water conservancy and hydropower projects, as well as environmental remediation projects, frequently encounter damp and water-related operations. Furthermore, the maintenance of various underground tunnels, mines, tunnels, pipe corridors, and other structures, as well as bathrooms, swimming pools, bridge piers, and wharf dams, often requires operations while wet. Due to interference from water molecules, traditional curing agents (including unmodified amines) are difficult to adapt to damp conditions, especially underwater conditions (as clearly stipulated in the "Technical Requirements and Test Methods for Underwater Adhesives (JT / T 215-2022)"). Generally, underwater construction materials should possess at least the following unique properties: 1. Good hydrophobicity, not easily swollen or dissolved by water; 2. Moderate viscosity, neither dispersed by water flow nor obstructed by water flow; 3. Low organic solvent content, not polluting the surrounding water quality; 4. Smooth application or pouring of the slurry in water, with high spreading and wetting properties; 5. The curing agent does not turn white, spread, or deteriorate when exposed to water; 6. The curing process is largely unaffected by water and water temperature, ideally curing completely at the freezing point (0℃); 7. Strong adhesion, stable water resistance, and minimal strength decay during long-term underwater use.

[0003] In recent years, researchers have developed various specialized products to meet different engineering needs. Patent CN103409090B describes an epoxy sealant for use in humid environments. While its water resistance is significantly improved compared to unsaturated polyester, with an initial compressive shear strength of 16.7–23.8 MPa, this value drops to 13.7–19.2 MPa after only 12 days of immersion in water at 25°C, showing a noticeable weakening. Furthermore, the addition of toxic solvents such as xylene, benzyl alcohol, and ethyl acetate poses a potential environmental risk, and its underwater bonding capability remains unclear.

[0004] Patents CN101619201B and CN108865034B each disclose an underwater fast-curing epoxy adhesive, but do not discuss in detail the underwater workability and water resistance stability of the adhesive.

[0005] Similarly, patents CN107298958B and CN106700992A both provide epoxy adhesives suitable for underwater environments, but neither has explored their underwater workability in detail. Patent application CN106700992A discloses a high-performance underwater-curing epoxy anchoring adhesive, its preparation method, and its application. This epoxy anchoring adhesive consists of two components, A and B. By weight, component A comprises: 45-75 parts epoxy resin, 3-9 parts reactive diluent, 0.6-0.9 parts coupling agent, 3-9 parts toughening agent, 25-35 parts inorganic filler, and 5-10 parts thixotropic agent; component B comprises: 5-10 parts accelerator, 40-80 parts curing agent, 20-25 parts inorganic filler, 0.3-0.6 parts coupling agent, and 10-15 parts thixotropic agent.

[0006] In essence, CN106700992A uses semi-solid E44 (or F44) type epoxy and liquid nitrile rubber, and incorporates a large dose of fumed silica thixotropic agent, and is mostly used as a rebar anchoring adhesive. The slurry is viscous and lacks dispersants that improve filler wettability, leveling agents that enhance flow / leveling, and defoamers, inevitably resulting in poor spreadability and difficulty in grouting and penetrating narrow cracks; furthermore, the water resistance of the solidified body (such as strength changes after long-term or high-temperature immersion in water) cannot be verified. Secondly, the component combination lacks rationality. For example, the active amino group in γ-aminopropyltriethoxysilane (KH-550) can induce epoxy ring opening, and the glycidyl ether functional group in γ-glycidyl etheroxypropyltrimethoxysilane (KH-560) can also react with amine curing agents. Therefore, KH-550 can only be added to component B (curing agent system), and KH-560 can be added to component A (epoxy system). If not distinguished, as the applicant stated, the coupling agents in components A and B can be the same or different, so both are likely to gel prematurely during storage and transportation.

[0007] Patent application CN116283055A reports an epoxy repair material that is resistant to water dispersion and boiling at 65°C. It can be applied smoothly on and under water, and its water aging resistance fluctuates little. The maximum adhesive strength to mortar blocks is 3.06 MPa. Although this index meets the requirements of most underwater repair scenarios, the bonding reliability is still insufficient for some structural parts that need to withstand special loads.

[0008] Furthermore, the curing agents or modifiers used in the aforementioned patents all originate from the petrochemical industry, and their production, processing, and use are all detrimental to emission reduction and carbon reduction. Summary of the Invention

[0009] The technical problem to be solved by this invention is to provide a biomass underwater curing agent, an epoxy composition, and a method for preparing the same, addressing the shortcomings of existing technologies. The composition has a wide range of application options, including coating, grouting / injection, and complete curing both above and below water, exhibiting high and stable overall strength.

[0010] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0011] A biomass underwater curing agent, characterized in that the underwater curing agent is prepared by methylamination reaction of aromatic phenol monomers, aldehyde monomers and straight-chain amine monomers, wherein the long straight-chain repeating unit of the aromatic phenol monomer has a length of not less than 10 carbon atoms.

[0012] The aromatic phenol monomer is selected from at least one of cashew acid, hydrogenated cashew acid, cashew phenol, hydrogenated cashew phenol and its derivatives, preferably at least one of cashew phenol and hydrogenated cashew phenol.

[0013] The aromatic phenol monomers are extracted from natural, renewable, non-food chain plants. The molecules contain aromatic rings, phenolic hydroxyl groups, and long, straight aliphatic side chains, with each long straight side chain segment having a length of at least 10 carbon atoms. The aromatic rings provide the curing agent with good hardness, heat resistance, hydrophobicity, and mechanical strength. The phenolic hydroxyl groups have the activity of promoting epoxy ring-opening at low temperatures, allowing the epoxy resin to crosslink even at the freezing point (0°C). They can also improve adhesion by forming intermolecular hydrogen bonds. The long, straight aliphatic side chains reduce the viscosity of the curing agent (low entanglement of non-branched straight chains, low viscosity), enhance hydrophobicity and toughness (high rotational freedom of the long chain configuration effectively dissipates external impact energy and improves low-temperature brittleness).

[0014] Given that cashew acid and hydrogenated cashew acid molecules are rich in carboxyl groups, they are easily neutralized into esters under alkaline atmosphere, thus affecting the water resistance (alkaline) of the solidified body. Therefore, at least one of cashew phenol and hydrogenated cashew phenol is preferred.

[0015] The aldehyde monomer is selected from at least one of formaldehyde, furfural, benzaldehyde, octoxymethylene, nonoxymethylene, and decaoxymethylene, preferably at least one of furfural, benzaldehyde, octoxymethylene, nonoxymethylene, and decaoxymethylene.

[0016] The present invention also discloses an epoxy composition comprising two components, A and B. By weight, component A contains 65-85 parts epoxy resin, 10-15 parts reactive diluent, 1-5 parts toughening agent, 2-8 parts coupling agent, 0.1-0.5 parts defoamer, 1-3 parts wetting and dispersing agent, 0.5-1 part leveling agent, 20-40 parts fiber, 150-300 parts filler, 5-7 parts anti-settling agent, and 0-0.5 parts coloring pigment; component B contains 97-100 parts underwater curing agent and 1-3 parts curing accelerator.

[0017] The viscosity of the resulting composition is 800–3000 cp.

[0018] Studies have found that the long and straight aliphatic side chains of the aromatic phenol monomers reduce the viscosity of the underwater curing agent (low entanglement of non-branched straight chains, low viscosity), and enhance hydrophobicity and toughness (high rotational freedom of long-chain configuration, which can effectively dissipate external impact energy and improve low-temperature brittleness). Paraformaldehyde contains little residual formaldehyde monomer and has good flexibility, but it has certain water solubility when the polymerization level is too low (≤7), and the reactivity is weak when the polymerization level is too high (>10). This application specifically screens aldehyde and phenol monomers, taking into account the ecological nature of raw materials, reactivity, and production costs. It increases the versatility of equipment, reduces the difficulty of the reaction, simplifies the process, saves reaction energy consumption, shortens the reaction time, and avoids the formation of by-products, resulting in a synthesized compound with a suitable molecular weight and gel time, and good stability in water (no whitening, no diffusion).

[0019] The resulting composition has a viscosity of 800–3000 cp. If the viscosity is too low, the slurry is easily dispersed by water flow disturbance; if the viscosity is too high, it is not easy to spread, flow / level or the coating is too thick.

[0020] More preferably, component A contains 75-85 parts epoxy resin, 12-15 parts reactive diluent, 3-5 parts toughening agent, 2-8 parts coupling agent, 0.1-0.5 parts defoamer, 1-3 parts wetting and dispersing agent, 0.5-1 part leveling agent, 20-40 parts fiber, 150-300 parts filler, 5-7 parts anti-settling agent, and 0-0.5 parts coloring pigment; component B contains 97-100 parts underwater curing agent and 1-3 parts curing accelerator.

[0021] In a preferred embodiment of the present invention, the epoxy resin contains 45-55 parts of liquid bisphenol A epoxy and 20-30 parts of liquid bisphenol F epoxy, or contains 50-60 parts of liquid hydrogenated bisphenol A epoxy and 15-25 parts of liquid bisphenol F epoxy; preferably, the epoxy values ​​of the liquid bisphenol A epoxy, liquid hydrogenated bisphenol A epoxy, and liquid bisphenol F epoxy are all 0.51-0.54 mol / g, and the hydrolyzed chlorine content is ≤300 ppm.

[0022] Bisphenol A epoxy and hydrogenated bisphenol A epoxy are inexpensive and widely used in the coatings, inks, and adhesives industries. However, they have high viscosity at room temperature (e.g., E51 resin is approximately 12,000–15,000 cp), making them difficult to flow in winter. Bisphenol F epoxy has a relatively regular molecular chain, low steric hindrance, and low viscosity (e.g., F51 resin is only 2,000–5,000 cp), but its price is higher. Mixing them can achieve suitable viscosity and cost control, and can avoid crystallization at low temperatures. Preferably, the epoxy values ​​of the liquid bisphenol A, hydrogenated bisphenol A, and bisphenol F epoxy in component A are all 0.51–0.54 mol / g, and the hydrolyzed chlorine content is ≤300 ppm. This type of epoxy resin has good mechanical strength. Mixing the two can reduce the system viscosity to 1 / 3–1 / 4 of the original pure (hydrogenated) bisphenol A epoxy, facilitating the subsequent addition of large amounts of powder fillers; the low chlorine value also effectively prevents chloride precipitates. - Hydrolysis leads to a decrease in the adhesion, water resistance, and corrosion resistance of the solidified body.

[0023] In a preferred embodiment of the present invention, the active diluent contains glycidyl ether or glycidyl ester structure, preferably one or more of aliphatic monoglycidyl ether or ester, alicyclic monoglycidyl ether or ester, aromatic monoglycidyl ether or ester and their derivatives; to prevent possible hydrolysis of the ester group in water and alkaline water, one or more of the monoglycidyl ethers are further preferred; even more preferably, the active diluent is cashew phenol monoglycidyl ether.

[0024] Compared to aliphatic and alicyclic monoglycidyl ethers, the benzene ring configuration in cashew phenol monoglycidyl ether makes its strength and temperature resistance more stable, while the long straight C15 side chain is more hydrophobic and tougher than ordinary aromatic compounds, and can also improve its compatibility with the biomass underwater curing agent.

[0025] In a preferred embodiment of the present invention, the toughening agent is selected from one or more of liquid polyether, polysulfide, nitrile rubber, core-shell macromolecules, hyperbranched polymers, ethylene glycol diglycidyl ether (ester), diethylene glycol diglycidyl ether (ester), triethylene glycol diglycidyl ether (ester), propylene glycol diglycidyl ether (ester), dipropylene glycol diglycidyl ether (ester), tripropylene glycol diglycidyl ether (ester), hexanediol diglycidyl ether (ester), cyclohexanediol diglycidyl ether (ester), butylene glycol diglycidyl ether (ester), neopentyl glycol diglycidyl ether (ester), polyethylene glycol diglycidyl ether (ester), polypropylene glycol diglycidyl ether (ester), cashew nut phenol diglycidyl ether (ester), and their derivatives; preferably, the toughening agent is cashew nut phenol diglycidyl ether.

[0026] Considering factors such as cost (core-shell macromolecules and hyperbranched polymers are relatively expensive and have complex preparation processes), compatibility with epoxy systems (the "sea-island" structure formed by liquid rubber in a three-dimensional cross-linked network easily induces interfacial separation), and water solubility (diol diglycidyl ethers (esters) and their derivatives have a certain degree of solubility / hydrolysis in water, which is not beneficial for water dispersion resistance), cashew phenol diglycidyl ether is preferred, such as LITE 513DF from Cardlä Chemical. The long C15 chain on the synergistic side of the diglycidyl ether structure allows the matrix to absorb and dissipate energy through molecular rotation when subjected to mechanical forces or thermal shocks, thereby improving its brittleness. Furthermore, through repeated comparisons, we have confirmed that cashew phenol diglycidyl ether has superior water resistance and corrosion protection compared to ethylene glycol diglycidyl ether.

[0027] In a preferred embodiment of the present invention, the coupling agent molecule contains both glycidyl ether and alkoxy units, and the coupling agent is selected from at least one of glycidyl ether-propyltrimethoxysilane, glycidyl ether-propylmethyldiethoxysilane, glycidyl ether-propyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and their derivatives; preferably, the coupling agent is selected from one or two of glycidyl ether-propyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0028] Glycidyl ether propyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane have low viscosity and good compatibility with resin systems. While promoting adhesion, methoxysilane reacts with water molecules faster and more easily than ethoxysilane, thus removing moisture from the surface of the composition more promptly and efficiently, and preventing water vapor from penetrating deeper into the interior. Practice has shown that, at the same dosage, glycidyl ether propyltrimethoxysilane removes water 0.4 to 1 times faster than glycidyl ether propyltriethoxysilane, transforming damp surfaces into a hydrophobic state in a short period. Similarly, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane exhibit similar characteristics.

[0029] In a preferred embodiment of the present invention, the defoamer is a modified organosilicon or a modified organofluorosilicone, selected from one or more of BYK-141, BYK-A530, BYK-A535, and BYK-066N.

[0030] Defoamers are mainly used to suppress and eliminate bubbles generated during the mixing stage, thereby improving the density of the solidified body.

[0031] In a preferred embodiment of the present invention, the wetting and dispersing agent is a polymeric alkyl amino salt, selected from one or more of BYK-9076, BYK-110, and BYK-W965.

[0032] The wetting and dispersing agent can effectively improve the wettability of organic resin to inorganic powder, so that the hydrophilic surface of the powder is completely coated by epoxy or its diluent, and then transformed into a hydrophobic state, while also having the effects of reducing viscosity and preventing sedimentation.

[0033] The leveling agent can promote the flow and leveling of the slurry along the surface of the substrate, and is selected from at least one of BYK-354, BYK-306, BYK-310, BYK-320, and BYK-333.

[0034] The fiber has a median particle size of 30-100 μm and is selected from one or more of wood fiber, glass fiber, steel fiber, and carbon fiber. Considering cost-effectiveness and raw material availability, acid and alkali resistant glass fiber is preferred.

[0035] The one-dimensional morphology of fibers can effectively reinforce zero-dimensional powders, connecting them from their independent and dispersed states into a unified whole through "bridging".

[0036] The filler is selected from one or more of modified or unmodified silica fume, titanium dioxide, calcium carbonate, feldspar powder, talc powder, mica powder, and ultrafine cement, and is used to increase the hardness, modulus, specific gravity, and temperature resistance of the composition, reduce costs, and decrease the coefficient of linear expansion.

[0037] The anti-settling agent can prevent the high-density filler in component A from segregating and settling during storage and transportation. It is selected from at least one of modified polyethylene wax, polyamide wax, fumed silica, organobentonite, and hydrogenated castor oil.

[0038] There are no special restrictions on the coloring pigments, as long as they are not water-soluble. The type of pigment and whether to add it should be determined based on the actual situation.

[0039] The curing accelerator is selected from one or more of 2-ethyl-4-methylimidazolium, triethanolamine, diethanolamine, ethanolamine, 2,4,6-tris(dimethylaminomethyl)phenol, cashew nut phenol and its derivatives; preferably cashew nut phenol has low viscosity, low temperature activity and properties similar to underwater curing agents.

[0040] The straight-chain amine monomers in the underwater curing agent are selected from at least one of ethylenediamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine. Their chains are flexible, have low viscosity, and react quickly. As the most common and relatively inexpensive aliphatic monomers for curing agent modification, they can provide the necessary primary and secondary amine groups for room-temperature crosslinking of epoxy resins.

[0041] The composition has a viscosity of 800-3000 cp and can be applied by coating, grouting, or injection, including but not limited to above-water and underwater operations.

[0042] The present invention also discloses a method for preparing the epoxy composition, comprising the following steps: when using, components A and B are mixed in a mass ratio of (7-8):1 and stirred thoroughly; preferably, the stirring speed is 400-600 r / min and the stirring time is 3-5 min. If the ambient temperature is too low (≤5℃), the mixed slurry can be allowed to stand and mature for 5-10 min before construction.

[0043] The synthesis route for the underwater curing agent is as follows:

[0044] In a multi-port reactor equipped with a condenser, thermometer, stirrer, and feeder, biomass aromatic phenol monomers and linear amines are added sequentially. The mixture is heated to 70–75°C to ensure uniform dissolution, then cooled to 45–50°C and maintained thereafter. Aldehyde monomers are slowly added in three portions over 1–1.5 hours with continuous stirring. After the aldehyde addition is complete, the temperature is adjusted to 80–85°C and refluxed for 2–3 hours. The reaction is controlled at the appropriate point, and the resulting water is removed by vacuum separation. The mixture is then cooled to room temperature, and the resulting yellow, viscous substance is the target product. The molar ratio of each component is n(aromatic phenol):n(aldehyde):n(linear amine) = 1:(0.9–1.1):(1.05–1.2).

[0045] The specific principles behind this application are as follows:

[0046] The long, straight, carbon-15 aliphatic side groups on the cashew phenol chain segments in the reactive diluent, toughening agent, curing agent, and curing accelerator impart good hydrophobicity to components A and B, reduce viscosity, and enhance the toughness of the crosslinked network. Furthermore, the curing agent molecule contains no hydrolyzable ester groups and contains specific lengths of paraformaldehyde (degree of polymerization n = 8–10) or benzaldehyde, primary / secondary amines, or phenolic hydroxyl units. With the timely removal of surface moisture from the slurry by the coupling agent, preventing its deep penetration and promoting adhesion, the composition possesses low-temperature, high-humidity (including underwater) curing ability and water resistance (stable strength over long-term use). The suitable slurry consistency (800–3000 cp) and the combination of wetting and dispersing agents, leveling agents, and defoamers not only enable rebar installation as described in patent application CN106700992A, but can also be used as a grouting or injection adhesive for filling narrow gaps (requiring lower viscosity and higher flow / leveling properties).

[0047] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0048] 1. This composition exhibits excellent flow and leveling properties, allowing for the sealing of various gaps with a width of at least 1mm using pressure grouting; large cavities or holes exceeding 5mm can be filled directly using the "self-weight method" or "high-level funnel method" without even requiring pressure. During underwater operations, its excellent hydrophobicity effectively repels and drains most of the moisture near the substrate, ensuring effective adhesion and curing. The coupling agent in the composition further eliminates any residual moisture, mitigating its negative impact on epoxy crosslinking. The application method is flexible, allowing for complete curing in low-temperature, high-humidity (including underwater) environments.

[0049] II. A well-balanced combination of raw materials maximizes synergistic benefits and ensures long-term stability during storage. All components are free of volatile solvents, resulting in zero VOC emissions and no pollution to the surrounding water. The diluent, toughening agent, accelerator, and underwater curing agent share the same origin (all belonging to the biomass cashew nut shell system), reducing the risk of cross-linking and improving hydrophobicity, enabling underwater solidification and resistance to both high temperatures and saline / fresh water. The wetting and dispersing agent improves the wettability of the filler, reduces its oil absorption value, and facilitates resin encapsulation; the leveling agent enhances the flow and leveling of the slurry; the high aspect ratio and linear fibers act as a "bridging" link for the micro / nano powders, forming an organic whole with the epoxy cross-linked network in conjunction with the coupling agent, thus improving tensile and flexural strength. In addition, each additive has multiple functions. For example, the viscosity of cashew phenol diglycidyl ether is less than 200 cp, which is much lower than that of liquid nitrile rubber (>>10000 cp) and hyperbranched polymers (>1500 cp). It can toughen the system while also diluting it. The highly active coupling agent can not only promote adhesion, but also remove residual moisture in time, so that the slurry is in a relatively anhydrous state, which is conducive to its rapid spreading, wetting and penetration on the substrate surface.

[0050] 3. The epoxy composition has a moderate viscosity, making it resistant to being washed away even by strong water currents, and can be applied by coating or poured into narrow cavities. It exhibits good hydrophobicity, making it difficult to swell or dissolve in water; it has high environmental tolerance, dries quickly at low temperatures (0°C), and shows minimal difference in curing performance between above and below water. The solidified body is strong and tough, resistant to mechanical forces or thermal shocks, and contains no easily hydrolyzed groups such as ester groups, thus resisting water / acid / alkali / salt corrosion. It can meet the material's resistance requirements under different salinity conditions in various water bodies, and its performance degradation is not significant after long-term underwater use.

[0051] IV. Using green, natural, and recyclable cashew phenol (acid) as a reaction substrate, a biomass underwater curing agent was designed and synthesized that is more adaptable to low-temperature and high-humidity environments than traditional or modified phenolic amines, and does not turn white or diffuse in water. Cashew phenol (acid) can be extracted from coconut shell oil, and is light in color, low in viscosity, environmentally friendly, and non-toxic. It is an ideal substitute for fossil-based nonylphenol and aromatic phenols, which are highly carcinogenic and teratogenic. The phenolic hydroxyl group, benzene ring, aliphatic carbon 15 long straight side chain, and unsaturated double bond structure in the molecule give it many excellent properties. After introducing paraformaldehyde, furfural, benzaldehyde, and straight-chain amines, its hydrophobicity, flexibility, water resistance, and underwater crosslinking activity are further improved. The preparation method has low equipment requirements and is simple and easy to implement, providing a valuable reference for the modification of non-petrochemical amines.

[0052] Based on the above characteristics, this biomass underwater curing agent and its composition are suitable for various scenarios such as north and south, winter and summer, inland rivers and seas, and above-water and underwater operations. It can be used for applications such as screw fixing, equipment foundation filling, track installation, and underwater pier reinforcement. It can be applied by coating, grouting, or injection. Attached Figure Description

[0053] Figure 1 This study examines the underwater curing agent of biomass and a commercially available phenolic amine in water, as well as the water dispersion resistance of their respective epoxy compositions.

[0054] Figure 2 Example 2 illustrates the construction effect of the epoxy composition on underwater concrete. The slurry has a moderate viscosity, is not easily washed away by water flow, has good spreading and wetting properties, and can form a smooth, uniform coating layer on the concrete surface.

[0055] Figure 3 This is a comparison of the underwater bonding strength of the epoxy compositions in Example 1 and Comparative Example 2 to carbon steel and concrete.

[0056] Figure 4 The epoxy compositions of Examples 1, 2 and Comparative Example 2 are tested for their resistance to 50°C hot water after being applied underwater to carbon steel plates and fully cured.

[0057] Figure 5 The compressive fracture resistance of the epoxy compositions in Example 1 and Comparative Example 1 is shown. Detailed Implementation

[0058] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. Without conflict, the embodiments and features of the present invention can be combined with each other.

[0059] Performance testing was conducted in accordance with the "Technical Specification for Safety Appraisal of Strengthening Materials for Engineering Structures (GB 50728-2011)," "Code for Acceptance of Construction Quality of Strengthening Engineering of Building Structures (GB 50550-2010)," and "Code for Design of Strengthening Concrete Structures (GB 50367-2013)." Underwater-cured samples were prepared directly underwater and cured at 23±2℃ for 7 days. Above-water-cured samples were prepared in a dry state and cured in a constant temperature chamber at 50±5% relative humidity and 23±2℃ for 7 days.

[0060] Cashew phenol monoglycidyl ether was selected from Cardlä Chemical's NC-513, Ultra LITE 513, and LITE 513E, or Xinyuan Chemical's XY767. Its viscosity is only 20-35 cp, and it is resistant to water, acid, alkali, and salt corrosion. All other raw materials and reagents were also purchased through normal commercial channels.

[0061] Example 1

[0062] Synthesis of underwater biomass solidification agent:

[0063] In a multi-port reactor equipped with a condenser, thermometer, stirrer, and feeder, 1 mol of cashew phenol and 1.2 mol of triethylenetetramine were added sequentially. The mixture was heated to 75°C to dissolve and homogenize the two substances. The temperature was then lowered to 45°C and maintained thereafter. Under continuous stirring, 1.1 mol of paraformaldehyde was slowly added in three portions over 1.5 hours. After the aldehyde addition was complete, the mixture was heated to 85°C and refluxed for 2.5 hours. The reaction was controlled at specific points, and the resulting water was removed by vacuum separation. The mixture was then cooled to room temperature for later use.

[0064] The product was tested and found to be a yellow, viscous substance with a Gardner color of 11, a viscosity of 1670 cp at 23°C, a solid content of 98.4%, an active hydrogen equivalent of 142, and a gel time (50g) of approximately 43 minutes.

[0065] Epoxy composition preparation process:

[0066] ① Add 55 parts of E-51 epoxy, 25 parts of F-51 epoxy, 12 parts of cashew phenol monoglycidyl ether, 5 parts of cashew phenol diglycidyl ether, 6.5 parts of glycidyl ether propyltrimethoxysilane, 0.5 parts of BYK-066N, 2.5 parts of BYK-9076, and 0.5 parts of BYK-354 into the reactor at once and mix at 800-1000 r / min until homogeneous; then add 32 parts of acid and alkali resistant glass fiber, 215 parts of modified silica powder, 5 parts of fumed silica, and 0.15 parts of phthalocyanine blue in batches and stir at 2000-3000 r / min to form a paste to obtain component A.

[0067] ② Mix 97 parts of the above-synthesized biomass underwater curing agent and 3 parts of cashew phenol at 1000-1200 r / min for 5-10 min until homogeneous to obtain component B.

[0068] ③ In actual use, components A and B should be mixed thoroughly at a mass ratio of 7:1 at 400-600 r / min for 3-5 minutes. If the temperature is too low (≤5℃), the mixed slurry can be allowed to stand and mature for 5-10 minutes before construction.

[0069] Example 2

[0070] Synthesis of underwater biomass solidification agent:

[0071] In a multi-port reactor equipped with a condenser, thermometer, stirrer, and feeder, 1 mol of cashew phenol and 1.05 mol of diethylenetriamine were added sequentially. The mixture was heated to 70°C to dissolve the two substances uniformly, then cooled to 45°C and maintained thereafter. 0.95 mol of benzaldehyde was slowly added dropwise in three portions over 1 hour with continuous stirring. After the aldehyde addition was complete, the mixture was heated to 80°C and refluxed for 2 hours, controlling the reaction time. The resulting water was removed by vacuum separation, and the mixture was cooled to room temperature for later use.

[0072] The product was tested and found to be a yellow, viscous substance with a Gardner color of 10, a viscosity of 1250 cp at 23°C, a solid content of 98.1%, an active hydrogen equivalent of 134, and a gel time (50g) of approximately 38 minutes.

[0073] Epoxy composition preparation process:

[0074] ① Add 50 parts of E-54 epoxy, 28 parts of F-54 epoxy, 13 parts of cashew phenol monoglycidyl ether, 4 parts of cashew phenol diglycidyl ether, 6 parts of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 0.4 parts of BYK-141, 3 parts of BYK-110, and 0.6 parts of BYK-306 into the reactor at once and mix at 800-1000 r / min until homogeneous; then add 40 parts of acid and alkali resistant glass fiber, 200 parts of ultrafine silicate cement, and 6 parts of organobentonite in batches and stir at 2000-3000 r / min to form a paste, thus obtaining component A.

[0075] ② Mix 98 parts of the above-synthesized biomass underwater curing agent and 2 parts of cashew phenol at 1000-1200 r / min for 5-10 min until homogeneous to obtain component B.

[0076] ③ In actual use, components A and B should be mixed at a mass ratio of 7.5:1 at 400-600 r / min for 3-5 minutes until fully mixed. If the temperature is too low (≤5℃), the mixed slurry can be allowed to stand and mature for 5-10 minutes before construction.

[0077] Comparative Example 1

[0078] A commercially available phenolic amine T-31 (phenol-formaldehyde-ethylenediamine modified product) was selected in equal amounts to replace the biomass underwater curing agent. The remaining components, dosages, preparation methods, and usage methods of the composition were the same as in Example 2. Based on the epoxy equivalent of the resin system and the active hydrogen equivalent of the curing agent, the ratio of groups A to B was 20:1.

[0079] Comparative Example 2

[0080] A well-known international building materials manufacturer sells a similar underwater curing epoxy grouting product, with triethylenetetramine and phenol modified as the curing agent.

[0081] Comparative Example 3

[0082] Except for replacing cashew phenol monoglycidyl ether with an equal amount of butyl glycidyl ether, cashew phenol diglycidyl ether with an equal amount of polypropylene glycol diglycidyl ether, cashew phenol diglycidyl ether with an equal amount of isopropyltris(dioctylpyrophosphate)titanate with glycidyl ether-propyltrimethoxysilane, and cashew phenol with an equal amount of triethanolamine, the remaining components, dosage, preparation and usage of the composition are the same as in Example 1.

[0083] The overall performance of the epoxy compositions in each embodiment and comparative example under water curing conditions is shown in Table 1.

[0084] Table 1. Curing properties of epoxy compositions in examples and comparative examples

[0085]

[0086] From the appendix Figures 1-5 Based on the data in Table 1, it is easy to see that the biomass underwater solidifying agents synthesized in Examples 1 and 2 are highly hydrophobic, retain their original color in water, do not turn white, have good anti-dispersion properties, and produce clear surrounding water with no dissolved substances. Figure 1 b). Based on this, the carefully formulated composition of Example 1 (or 2) exhibits a regular morphology and clear boundaries in water, and can aggregate into clusters even when disturbed by water flow. Figure 1 c). Traditional phenolic amines (including T-31 used in Comparative Example 1) have a certain degree of water solubility, and in water they are mostly cloudy white emulsions, or even solutions. Figure 1 a) Such epoxy compositions are too hydrophilic; the organic components swell / dissolve in water and lose their colloidal properties, making it difficult to bind the powdered filler. As a result, they easily disperse back into granules when slightly disturbed by water flow. Figure 1 d).

[0087] The composition of Example 1 (or 2) is hydrophobic but can be easily coated and impregnated. Figure 2It can cure at 0℃. The solidified body has excellent mechanical strength, and the adhesion is much higher than that of patent application CN116283055A (6.05MPa vs. 3.06MPa). The performance difference between the two curing methods is not significant. Compared to water curing, underwater curing results in a slight decrease in adhesion (<10%), lower than the existing technology CN103409090B (a decrease of 18-20%). It exhibits long-lasting and stable temperature resistance (>67℃) and salt resistance (3% NaCl) (only small areas peel off under strong rubbing), making it adaptable to different aquatic environments such as inland freshwater and marine saltwater. Figure 4 a, 4c).

[0088] Figure 3 This comparison examines the underwater bond strength of the epoxy compositions in Example 1 and Comparative Example 2 to carbon steel and concrete. Example 1 showed a bond strength as high as 7.81 MPa with both carbon steel and concrete. Figure 3 a) 6.05MPa Figure 3 c) The concrete cohesion fails, and it may even be torn off in large pieces. Foreign competing products (Comparative Example 2) lack sufficient hydrophobicity, allowing water molecules to penetrate the adhesive layer, severely affecting adhesion to the substrate, and causing almost complete detachment when bonding carbon steel. Figure 3 b).

[0089] Regarding water resistance stability, such as Figure 4 As shown, Example 1 ( Figure 4 a) Example 2 Figure 4 c) The adhesion is reliable. The adhesive layer, after being soaked in 50℃ fresh water and 50℃ 3% NaCl saline solution for 9 days, still adheres well to the substrate, as indicated by the arrow in the figure. It is not easily detached even when forcefully scraped with a carving knife. Comparative Example 2 uses hot fresh water (… Figure 4 b) Salt water ( Figure 4 d) After treatment, the adhesive properties are almost completely lost, and the entire adhesive layer can be peeled off by gently picking along the edge with a carving knife.

[0090] Comparative Example 4

[0091] Comparative Example 4 reduced the proportion of powder in the components. The difference between it and Example 1 is that the use of modified silica powder was eliminated (dosage was 0). The viscosity of the composition was reduced to about 710 cp. The slurry had stronger adhesiveness and fluidity, and could wet and penetrate into gaps less than 1 mm wide. However, it could be dispersed and carried away by a slow water flow of 5 m / min.

[0092] Comparative Example 5

[0093] The difference between Comparative Example 5 and Example 1 is that the amount of silicon micropowder is doubled (430 parts), the slurry is close to semi-solid and almost completely loses its flowability.

[0094] Therefore, the formulation design should take into account a comprehensive consideration of multiple factors such as its performance, application, and construction scenario.

[0095] The T-31 (phenol-formaldehyde-ethylenediamine modified compound) used in Comparative Example 1 has a simple molecular structure, lacks a carbon-15 aliphatic side groups, and has short and hydrophilic aldehyde and amine chains. The curing agent lacks toughness and hydrophobicity. Furthermore, due to residual small-molecule monomers, a small amount of organic matter (1.3%) volatilizes in the composition. In addition, its high activity, low dosage, and large A / B ratio result in an overly viscous slurry that is difficult to flow and level; various indicators are low, and it often breaks brittlely under external force. Figure 5 (a, 5b) Due to the influence of hydrophilicity, the underwater consolidation performance is severely weakened. After immersion in 50℃ fresh water and 3% NaCl salt water for 9 days, the adhesion of the coating is significantly weakened.

[0096] Figure 5 This reflects the compression fracture behavior of the epoxy compositions of Example 1 and Comparative Example 1. Due to the lack of toughness of T-31 (phenol-formaldehyde-ethylenediamine modified), under pressure... Figure 5 a, Figure 5 Both samples exhibited typical brittle cracking; the biomass curing agent in Example 1 was tough, and the sample underwent plastic deformation under external force. Figure 5 c. Figure 5 d).

[0097] Comparative Example 2 is from a well-known international brand and is currently widely used in various wet applications. Its tensile, flexural, compressive, and adhesive strengths during dry curing are comparable to those of Examples 1 or 2. However, its underwater curing ability is significantly lower than that above water, with a strength retention rate less than 60% of that above water, particularly noticeable in the decline in adhesive performance. Due to water penetration, the adhesion of the composition to aluminum-steel and aluminum-C45 concrete decreased sharply to 1.71 MPa and 3.10 MPa, respectively, representing decreases of 75.4% and 47.4% compared to above water. After immersion in fresh water and salt water at 50°C for 9 days, the coatings exhibited large-scale overall peeling. Figure 4 (b, 4d) The water resistance stability is not as good as that of Examples 1 or 2.

[0098] To further investigate the balancing effect of other materials on the composition's properties, Comparative Example 3 was replaced with commonly used diluents, toughening agents, coupling agents, and accelerators for dry curing. Tests showed that its water-based consolidation properties were essentially similar to those of Examples 1 and 2. However, butyl glycidyl ether and polypropylene glycol diglycidyl ether have limited hydrophobicity, and triethanolamine is even readily soluble in water, resulting in diffusion and shedding of the slurry in water (approximately). Figure 1 d) During application, it is difficult to remove all moisture from the substrate, hindering the spread and coating process. Furthermore, the low reactivity of titanate with water allows moisture to penetrate the coating and fail to be removed promptly, negatively impacting the cross-linking of the system and significantly impairing its various strengths. In our experiments, we observed a loose layer approximately 2–3 mm thick on the surface of the underwater samples, indicating incomplete curing due to water molecule interference.

[0099] In summary, through the careful design and green synthesis of the molecular structure of the biomass underwater curing agent, as well as the optimal combination of raw materials, the composition exhibits excellent hydrophobicity and water dispersibility, with minimal difference between underwater and above-water curing. The solidified body has reliable adhesion and is water-resistant and heat-stable, capable of adapting to working conditions such as low temperature (0℃), high humidity (including underwater), coating, and injection / pressurization operations. It can be used, but is not limited to, applications such as screw fixing, equipment foundation filling, track installation, and underwater pier reinforcement.

[0100] The above embodiments should be understood as being used only to more clearly illustrate the present invention, and not to limit the scope of the invention. After reading this invention, any modifications of these embodiments by those skilled in the art to various equivalent forms fall within the protection scope defined by the appended claims.

Claims

1. An epoxy composition, characterized by, The product comprises two components, A and B. By weight, component A contains 65-85 parts epoxy resin, 10-15 parts reactive diluent, 1-5 parts toughening agent, 2-8 parts coupling agent, 0.1-0.5 parts defoamer, 1-3 parts wetting and dispersing agent, 0.5-1 part leveling agent, 20-40 parts fiber, 150-300 parts filler, 5-7 parts anti-settling agent, and 0-0.5 parts coloring pigment. Component B contains 97-100 parts biomass underwater curing agent and 1-3 parts curing accelerator. The viscosity of the resulting composition is 800–3000 cp; The biomass underwater solidification agent is prepared by methylamination reaction of aromatic phenol monomers, aldehyde monomers and straight-chain amine monomers, wherein the length of the long straight side chain of the aromatic phenol monomer is not less than 10 carbon atoms. The active diluent is cashew phenol monoglycidyl ether; The toughening agent is cashew phenol diglycidyl ether; The coupling agent is selected from at least one of glycidyl ether propyltrimethoxysilane, glycidyl ether propylmethyldiethoxysilane, glycidyl ether propyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane. The curing accelerator is cashew nut phenol.

2. The epoxy composition according to claim 1, characterized in that, The epoxy resin contains 45-55 parts of liquid bisphenol A epoxy and 20-30 parts of liquid bisphenol F epoxy, or contains 50-60 parts of liquid hydrogenated bisphenol A epoxy and 15-25 parts of liquid bisphenol F epoxy.

3. The epoxy composition according to claim 2, characterized in that, The epoxy values ​​of the liquid bisphenol A epoxy, liquid hydrogenated bisphenol A epoxy, and liquid bisphenol F epoxy are all 0.51–0.54 mol / g, and the hydrolyzed chlorine content is ≤300 ppm.

4. The epoxy composition of claim 1, wherein The coupling agent is selected from one or two of glycidyl ether propyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

5. The epoxy composition of claim 1, wherein The aromatic phenol monomer is selected from at least one of cashew phenol and hydrogenated cashew phenol.

6. The epoxy composition of claim 1, wherein The aldehyde monomer is selected from at least one of formaldehyde, furfural, benzaldehyde, paraformaldehyde, nonaformaldehyde, and decaformaldehyde.

7. The epoxy composition of claim 1, wherein The composition has a viscosity of 800-3000 cp and is applied by coating, pouring, or injection for both above-water and underwater operations.

8. A method for preparing the epoxy composition according to any one of claims 1 to 7, characterized in that... The process includes the following steps: When using, mix components A and B at a mass ratio of (7-8):1 and stir thoroughly.

9. The method for preparing the epoxy composition according to claim 8, characterized in that, The mixing speed is 400-600 r / min and the mixing time is 3-5 min. If the ambient temperature is ≤5℃, let the mixed slurry stand for 5-10 min to mature before construction.

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