Modified epoxy resin material for repairing underwater concrete structure as well as preparation method and application of modified epoxy resin material

Abstract

The invention belongs to the technical field of underwater structure repairing materials, and relates to a modified epoxy resin material for repairing an underwater concrete structure as well as a preparation method and application of the modified epoxy resin material. The material comprises the following components in parts by weight: 40-60 parts of an epoxy resin matrix, 10-30 parts of a water reaction type isocyanate curing agent, 1-5 parts of a hydrophobic silane coupling agent, 2-8 parts of nanoscale silicon dioxide particles and 5-15 parts of a flexible polyether modifier. The water reaction type isocyanate curing agent is one or two of hexamethylene diisocyanate and isophorone diisocyanate; the hydrophobic silane coupling agent is gamma-glycidyl ether oxypropyl trimethoxy silane, and the hydrophobic silane coupling agent is gamma-glycidyl ether oxypropyl trimethoxy silane. The modified epoxy resin material disclosed by the invention has the advantages of rapid underwater curing, excellent mechanical properties, high water resistance, high corrosion resistance and the like, can adjust the working time and the curing speed, is environment-friendly, and is particularly suitable for scenes requiring rapid and efficient repair in an underwater environment.

Description

Technical Field

[0001] The invention belongs to the technical field of underwater structure repair materials, and specifically relates to a modified epoxy resin material for underwater concrete structure repair, a preparation method and an application thereof. Background Art

[0002] Underwater infrastructure such as offshore platforms, submarine pipelines, drilling facilities, submarine cables, bridges and docks are key components of offshore oil and gas exploration and production, information transmission and transportation. The foundations or supporting structures of these facilities are mostly made of underwater concrete. As the service time increases, underwater concrete structures are affected by factors such as chloride ion erosion, carbonization, freeze-thaw cycles, biological erosion and abrasion, and are prone to cracks, spalling, carbonization, steel bar corrosion and other diseases. If repair measures are not taken in time, it will lead to serious economic losses and safety hazards.

[0003] At present, common underwater concrete structure repair materials mainly include underwater epoxy resin, underwater repair glue and underwater fast-hardening cement. Underwater epoxy resin has good adhesion and corrosion resistance, but it is easy to debond and fail in low temperature and high humidity environment. Underwater repair glue is easy to construct, but the repair effect is limited by its own strength. Underwater fast-hardening cement has high strength, but poor adhesion to the original structure and is prone to shrinkage cracks. In recent years, new materials such as polymer-modified cement-based materials and fiber-reinforced composites have also been gradually used in underwater concrete repair, but there are still problems such as poor performance stability or high cost.

[0004] Ideal underwater concrete structure repair materials should have excellent adhesion and water resistance, fast curing ability, high strength and durability, good environmental adaptability and operability. However, existing materials still have shortcomings in meeting these requirements, especially in low temperature and high humidity marine environments, where performance is difficult to achieve ideal results.

[0005] Therefore, developing an underwater concrete structure repair material that can cure quickly under low temperature and high humidity conditions in the marine environment and has excellent mechanical properties and durability is of great significance for improving the maintenance efficiency and safety of marine engineering facilities. This can not only extend the service life of infrastructure, protect personnel and environmental safety, but also maintain the continuity of economic and social operations, and have a far-reaching impact on the sustainable development of marine engineering. Summary of the invention

[0006] In view of the problems of low strength, insufficient adhesion, long curing period and the like of existing underwater concrete structure repair materials, the present invention proposes a modified epoxy resin material for underwater concrete structure repair and a preparation method and application thereof. The material has the advantages of rapid underwater curing, excellent mechanical properties, strong water resistance and corrosion resistance, adjustable working time and curing speed, and is environmentally friendly. The material is particularly suitable for scenarios including underwater concrete structures including marine platforms, submarine pipelines, drilling facilities, submarine cables, bridges and docks, marine engineering, metal pipelines, ship maintenance and underwater concrete structures that require rapid and efficient repair in underwater environments, providing an innovative solution for the maintenance and repair of underwater infrastructure.

[0007] The technical solution of the present invention is:

[0008] A modified epoxy resin material for underwater concrete structure repair comprises the following components in parts by weight:

[0009] 40-60 parts of epoxy resin matrix, 10-30 parts of water-reactive isocyanate curing agent, 1-5 parts of hydrophobic silane coupling agent, 2-8 parts of nano-scale silica particles, and 5-15 parts of flexible polyether modifier;

[0010] The weight proportions of the above-mentioned epoxy resin matrix can be 40 parts, 42 parts, 45 parts, 48 ​​parts, 50 parts, 52 parts, 53 parts, 55 parts, 58 parts or 60 parts, but are not limited to the listed values. As long as they are within the range of 40-60 parts, other unlisted values ​​are also applicable.

[0011] The weight proportion of the water-reactive isocyanate curing agent can be 10 parts, 12 parts, 15 parts, 17 parts, 20 parts, 23 parts, 25 parts, 27 parts or 30 parts, but is not limited to the listed values. As long as it is within the range of 10-30 parts, other unlisted values ​​are also applicable.

[0012] The weight proportion of the hydrophobic silane coupling agent can be 1 part, 2 parts, 3 parts, 4 parts or 5 parts, but is not limited to the listed values. As long as it is within the range of 1-5 parts, other unlisted values ​​are also applicable.

[0013] The weight proportion of the nano-sized silica particles can be 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts or 8 parts, but is not limited to the listed values. As long as it is within the range of 2-8 parts, other unlisted values ​​are also applicable.

[0014] The weight proportion of the flexible polyether modifier can be 5 parts, 7 parts, 9 parts, 10 parts, 12 parts, 13 parts or 15 parts, but is not limited to the listed values. As long as it is within the range of 5-15 parts, other unlisted values ​​are also applicable.

[0015] The epoxy resin matrix is ​​prepared by reacting bisphenol A and epichlorohydrin in a molar ratio of 1:2 to 1:3 under alkaline conditions;

[0016] The water-reactive isocyanate curing agent is one or both of hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI);

[0017] The hydrophobic silane coupling agent is γ-glycidyloxypropyltrimethoxysilane.

[0018] Furthermore, the preparation method of the epoxy resin matrix comprises the following steps:

[0019] Bisphenol A and epichlorohydrin are mixed in a molar ratio of 1:2 to 1:3, nitrogen is introduced as a protective gas, and the mixture is reacted under alkaline conditions, and refluxed at 40 to 60° C. for 3 to 5 hours to obtain a crude product;

[0020] The crude product is subjected to reduced pressure distillation and purification at a temperature of 120-150° C. and a pressure of 0.1-1 kPa to obtain a bisphenol A epoxy resin.

[0021] Furthermore, the preparation method of the epoxy resin matrix comprises the following steps: (1) adding bisphenol A and epichlorohydrin in a molar ratio of 1:2 to 1:3 into a four-necked flask, and adding 50% sodium hydroxide aqueous solution to adjust the pH value to 10-12; (2) placing the reaction device in a constant temperature water bath, connecting a mechanical stirrer, a thermometer, a reflux condenser and a nitrogen inlet tube; (3) introducing nitrogen as a protective atmosphere at a flow rate of 2-3 bubbles / second, starting stirring, and rotating at a speed of 200-300rpm; (4) raising the reaction temperature to 40-60°C, maintaining the temperature range for reflux reaction for 3-5 hours to obtain a crude product; (5) transferring the crude product to a vacuum distillation device, performing vacuum distillation and purification under the conditions of a temperature of 120-150°C and a pressure of 0.1-1kPa to obtain a bisphenol A type epoxy resin.

[0022] Furthermore, the modified epoxy resin material comprises the following components by weight: 45-55 parts of epoxy resin matrix, 16-30 parts of water-reactive isocyanate curing agent, 2-4 parts of hydrophobic silane coupling agent, 4-6 parts of nano-scale silica particles, and 8-13 parts of flexible polyether modifier.

[0023] Furthermore, the average particle size of the nano-scale silica particles is 10 to 100 nm.

[0024] Furthermore, the flexible polyether modifier is polyoxypropylene glycol, and its molecular weight is 1000-3000, for example, it can be polyoxypropylene glycol with a molecular weight of 1000 or polyoxypropylene glycol with a molecular weight of 2000.

[0025] The present invention provides a method for preparing the modified epoxy resin material described in any one of the above, comprising the following steps:

[0026] (1) heating the epoxy resin matrix to 60-80° C. to melt it, and adding a hydrophobic silane coupling agent, nano-sized silica particles, and a flexible polyether modifier in sequence under stirring, stirring for 30-60 minutes at a stirring rate of 100-300 rpm;

[0027] The above-mentioned heating temperature is any temperature within the range of 60 to 80°C, for example, it can be 60°C, 62°C, 65°C, 68°C, 70°C, 72°C, 75°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0028] The stirring rate is any rate within the range of 100 to 300 rpm, for example, it can be 100 rpm, 120 rpm, 150 rpm, 170 rpm, 200 rpm, 230 rpm, 250 rpm, 280 rpm or 300 rpm, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0029] The stirring time is any time within the range of 30 to 60 min, for example, it can be 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 57 min or 60 min, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0030] (2) adding a water-reactive isocyanate curing agent, setting the stirring rate to 300 to 500 rpm, and stirring for 2 to 5 minutes to obtain a mixture;

[0031] The above stirring rate is any rate within the range of 300 to 500 rpm, for example, it can be 300 rpm, 320 rpm, 350 rpm, 370 rpm, 400 rpm, 430 rpm, 450 rpm, 480 rpm or 500 rpm, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0032] The stirring time is any time within the range of 2 to 5 minutes, for example, it can be 2 minutes, 2.5 minutes, 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes or 5 minutes, but is not limited to the listed values. Other values ​​not listed within the range are also applicable.

[0033] (3) The mixture is placed in a vacuum degassing machine with a vacuum degree of 0.1 to 1 kPa for degassing for 5 to 10 minutes to obtain a modified epoxy resin material.

[0034] The present invention also provides use of any of the modified epoxy resin materials described above in repairing underwater concrete structures.

[0035] Furthermore, the modified epoxy resin material is used as a repair material for the maintenance and repair of underwater concrete structures;

[0036] The underwater concrete structures include offshore platforms, submarine pipelines, drilling facilities, submarine cables, bridges and docks.

[0037] Beneficial effects of the present invention:

[0038] (1) The modified epoxy resin material of the present invention is compounded with an epoxy resin matrix using a water-reactive isocyanate curing agent. The water-reactive isocyanate curing agent can react with water in an underwater environment to generate amines, which then react with epoxy groups to achieve rapid curing. This curing mechanism enables the material to harden rapidly in a marine environment with low temperature (4°C-30°C) and high humidity (close to 100% relative humidity), greatly shortening the repair time.

[0039] (2) The present invention can control the curing speed and early strength of the material by reasonably adjusting the ratio of the epoxy resin matrix to the water-reactive isocyanate curing agent; the addition of a hydrophobic silane coupling agent significantly improves the adhesion of the material on the wet concrete surface; the introduction of nano-scale silica particles improves the mechanical strength and wear resistance of the material, while the flexible polyether modifier improves the toughness and low-temperature performance of the material.

[0040] (3) The modified epoxy resin material of the present invention is a polymer with a network structure, which can exist stably in a seawater environment. Its special molecular structure makes it have excellent water resistance and corrosion resistance, and can remain stable in seawater for a long time, forming an effective protective barrier to delay the penetration of harmful substances such as chloride ions. The modified epoxy resin material combines the following advantages:

[0041] Low polarity properties: Using alicyclic and aliphatic small molecules as modifiers improves the resin's ability to resist penetration and wetting in underwater environments.

[0042] Excellent water resistance: The material has low water absorption rate and high moisture barrier ability, and can remain stable for a long time.

[0043] Chemical reaction curing: Water-reactive isocyanate curing agent can cross-link with epoxy resin in an underwater environment to achieve rapid curing.

[0044] Strong physical adhesion: The material generates strong physical adhesion during the curing process and can firmly adhere to the surface of underwater steel structures.

[0045] (4) The modified epoxy resin material of the present invention can harden quickly underwater, form an effective bond to the wet concrete surface, and show high strength and durability in the marine service environment; its compressive strength can reach 50-80MPa, tensile strength is 10-15MPa, shear bond strength can reach 3-5MPa, impact strength is 40-60J / m, and seawater immersion strength retention rate is greater than 95%. The initial setting time is 0.5-1h, and the final setting time is 2-4h, which can meet the needs of underwater rapid repair; it has broad application prospects in the maintenance and emergency repair of underwater concrete structures such as marine platforms, submarine pipelines, bridges, and docks. DETAILED DESCRIPTION

[0046] In order to further understand the present invention, the technical scheme of the present invention will be clearly and completely described below in conjunction with the embodiments. The embodiments described in the present invention are only a part, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0047] If no specific techniques or conditions are specified in the examples, the reaction is carried out according to the conventional techniques in the art or the techniques or product specifications described in the literature. The reagents used are conventional products that can be purchased commercially unless otherwise specified. The instruments used, such as stirring and reflux reaction devices, are conventional products that can be purchased commercially unless otherwise specified.

[0048] Example 1

[0049] The present embodiment provides a modified epoxy resin material for repairing underwater concrete structures. The raw materials thereof include the following components, by weight: 50 parts of epoxy resin matrix, 10 parts of hexamethylene diisocyanate and 10 parts of isophorone diisocyanate, 3 parts of γ-glycidyloxypropyltrimethoxysilane, 5 parts of nano-scale silica particles with an average particle size of 50 nm, and 10 parts of polyoxypropylene glycol with a molecular weight of 2000.

[0050] The epoxy resin matrix is ​​prepared by the following steps: bisphenol A and epichlorohydrin are mixed in a four-necked flask at a molar ratio of 1:2.5, and a 50% sodium hydroxide aqueous solution is added to adjust the pH value to 11. The reaction device is placed in a constant temperature water bath, and a mechanical stirrer, a thermometer, a reflux condenser and a nitrogen inlet tube are connected. Nitrogen is introduced as a protective atmosphere at a flow rate of 2-3 bubbles / second, stirring is turned on, and the speed is 250rpm. The reaction temperature is raised to 50°C, and the temperature is maintained for stirring and reflux reaction for 4 hours to obtain a crude product.

[0051] The crude product was transferred to a vacuum distillation apparatus, and vacuum distilled and purified at 135° C. and 0.5 kPa to obtain a bisphenol A epoxy resin.

[0052] The modified epoxy resin material is prepared by using the above components in parts by weight through the following steps, specifically:

[0053] (1) heating the epoxy resin matrix to 70° C. to melt it, and adding γ-glycidyloxypropyltrimethoxysilane, nano-scale silica particles with an average particle size of 50 nm, and polyoxypropylene glycol with a molecular weight of 2000 in sequence under stirring at 200 rpm, and stirring for 45 minutes;

[0054] (2) adding hexamethylene diisocyanate and isophorone diisocyanate, and rapidly stirring at 400 rpm for 3 minutes to obtain a mixture;

[0055] (3) The mixture was placed in a vacuum degassing machine and degassed at 0.5 kPa for 8 minutes to obtain a modified epoxy resin material.

[0056] Application: The prepared modified epoxy resin material is coated on the surface of the underwater concrete slab and cured at 10°C for 24 hours until it is completely cured. Then its various performance indicators are tested. The measured properties are as follows: surface hardness (Shore D): 82, compressive strength: 68MPa, tensile strength: 13MPa, shear bond strength: 4.2MPa, impact strength: 52J / m, seawater immersion resistance strength retention rate: 97%, initial setting time: 0.8 hours, final setting time: 3.2 hours.

[0057] Example 2

[0058] This embodiment provides a modified epoxy resin material for underwater concrete structure repair, and its raw materials include the following components in parts by weight:

[0059] 40 parts of epoxy resin matrix, 10 parts of hexamethylene diisocyanate, 1 part of γ-glycidyloxypropyltrimethoxysilane, 2 parts of nano-scale silica particles with an average particle size of 50 nm, and 5 parts of polyoxypropylene glycol with a molecular weight of 2000.

[0060] Wherein, the epoxy resin matrix is ​​prepared by the following steps:

[0061] Bisphenol A and epichlorohydrin were mixed in a four-necked flask at a molar ratio of 1:2, and a 50% aqueous sodium hydroxide solution was added to adjust the pH value to 10. The reaction apparatus was placed in a constant temperature water bath, and a mechanical stirrer, a thermometer, a reflux condenser and a nitrogen inlet tube were connected. Nitrogen was introduced as a protective atmosphere at a flow rate of 2-3 bubbles / second, and stirring was turned on at a speed of 200rpm. The reaction temperature was raised to 40°C, and the temperature was maintained for stirring and reflux reaction for 5 hours to obtain a crude product.

[0062] The crude product was transferred to a vacuum distillation apparatus, and vacuum distilled and purified at 120° C. and 0.1 kPa to obtain a bisphenol A epoxy resin.

[0063] The modified epoxy resin material is prepared by using the above components in parts by weight through the following steps, specifically:

[0064] (1) heating the epoxy resin matrix to 60° C. to melt it, and adding γ-glycidyloxypropyltrimethoxysilane, nano-scale silica particles with an average particle size of 50 nm, and polyoxypropylene glycol with a molecular weight of 2000 in sequence under stirring at 100 rpm, and stirring for 60 min;

[0065] (2) adding hexamethylene diisocyanate and rapidly stirring at 300 rpm for 3 minutes to obtain a mixture;

[0066] (3) The mixture was placed in a vacuum degassing machine and degassed at 0.5 kPa for 8 minutes to obtain a modified epoxy resin material.

[0067] application:

[0068] The prepared modified epoxy resin material was coated on the surface of the underwater concrete slab and cured at 10°C water temperature for 24 hours until it was completely cured. Then its various performance indicators were tested. The measured performance was as follows:

[0069] Surface hardness (Shore D): 75, compressive strength: 52MPa, tensile strength: 10MPa, shear bond strength: 3.1MPa, impact strength: 41J / m, seawater immersion resistance strength retention rate: 95%, initial setting time: 1.0 hour, final setting time: 3.8 hours.

[0070] Example 3

[0071] The present embodiment provides a modified epoxy resin material for repairing underwater concrete structures. The raw materials thereof include the following components, measured by weight: 60 parts of epoxy resin matrix, 30 parts of isophorone diisocyanate, 5 parts of γ-glycidyloxypropyltrimethoxysilane, 8 parts of nano-scale silica particles with an average particle size of 50 nm, and 15 parts of polyoxypropylene glycol with a molecular weight of 2000.

[0072] The epoxy resin matrix is ​​prepared by the following steps: bisphenol A and epichlorohydrin are mixed in a four-necked flask at a molar ratio of 1:3, and a 50% sodium hydroxide aqueous solution is added to adjust the pH value to 12. The reaction device is placed in a constant temperature water bath, and a mechanical stirrer, a thermometer, a reflux condenser and a nitrogen inlet tube are connected. Nitrogen is introduced as a protective atmosphere at a flow rate of 2-3 bubbles / second, and stirring is turned on at a speed of 300rpm. The reaction temperature is raised to 60°C, and the temperature is maintained for stirring and reflux reaction for 3 hours to obtain a crude product;

[0073] The crude product was transferred to a vacuum distillation apparatus, and vacuum distilled and purified at 150° C. and 1 kPa to obtain a bisphenol A epoxy resin.

[0074] The modified epoxy resin material is prepared by using the above components in parts by weight through the following steps, specifically:

[0075] (1) heating the epoxy resin matrix to 80° C. to melt it, and adding γ-glycidyloxypropyltrimethoxysilane, nano-scale silica particles with an average particle size of 50 nm, and polyoxypropylene glycol with a molecular weight of 2000 in sequence under stirring at 300 rpm, and stirring for 30 min;

[0076] (2) adding isophorone diisocyanate and rapidly stirring at 500 rpm for 3 minutes to obtain a mixture;

[0077] (3) The mixture was placed in a vacuum degassing machine and degassed at 0.5 kPa for 8 minutes to obtain a modified epoxy resin material.

[0078] Application: The prepared modified epoxy resin material is coated on the surface of the underwater concrete slab and cured at 10°C for 24 hours until it is completely cured. Then its various performance indicators are tested. The measured properties are as follows: surface hardness (Shore D): 85, compressive strength: 78MPa, tensile strength: 15MPa, shear bond strength: 4.8MPa, impact strength: 58J / m, seawater immersion resistance strength retention rate: 98%, initial setting time: 0.6 hours, final setting time: 2.8 hours.

[0079] Comparative Example 1

[0080] This comparative example provides a repair material, which is different from Example 1 in that a common epoxy curing agent (diethylenetriamine) is used in its raw material components instead of a water-reactive isocyanate curing agent (hexamethylene diisocyanate and isophorone diisocyanate). The other component compositions and preparation steps are the same as those of Example 1.

[0081] The prepared repair material was coated on the surface of the underwater concrete slab and the performance was tested after curing at 10°C water temperature for 24 hours:

[0082] Surface hardness (Shore D): 65, compressive strength: 35MPa, tensile strength: 7MPa, shear bond strength: 1.8MPa, impact strength: 30J / m, seawater immersion resistance strength retention rate: 85%, initial setting time: 2.5 hours, final setting time: 8.0 hours.

[0083] The results show that not using water-reactive isocyanate curing agent will lead to insufficient curing of the material in an underwater environment and a significant decrease in various properties.

[0084] Comparative Example 2

[0085] This comparative example provides a repair material, which is different from Example 1 in that the amount of the hydrophobic silane coupling agent (γ-glycidyloxypropyltrimethoxysilane) is increased to 7 parts. The other components and preparation steps are the same as those in Example 1.

[0086] The repair material was applied to the surface of the underwater concrete slab and the performance was tested after curing at 10°C for 24 hours:

[0087] Surface hardness (Shore D): 80, compressive strength: 65MPa, tensile strength: 12MPa, shear bond strength: 3.0MPa, impact strength: 48J / m, seawater immersion resistance strength retention rate: 92%, initial setting time: 1.2 hours, final setting time: 4.0 hours.

[0088] The results show that excessive use of hydrophobic silane coupling agent will make the material too hydrophobic, affecting the bonding with the concrete surface and causing a decrease in shear bond strength.

[0089] Comparative Example 3

[0090] This comparative example provides a repair material, which is different from Example 1 in that the amount of epoxy resin matrix is ​​reduced to 35 parts.

[0091] The repair material was applied to the surface of the underwater concrete slab and the performance was tested after curing at 10°C for 24 hours:

[0092] Surface hardness (Shore D): 70, compressive strength: 45MPa, tensile strength: 9MPa, shear bond strength: 2.5MPa, impact strength: 38J / m, seawater immersion resistance strength retention rate: 90%, initial setting time: 1.5 hours, final setting time: 5.0 hours.

[0093] The results show that insufficient epoxy resin matrix will lead to a decrease in the overall performance of the material, especially the compressive strength and bonding strength will be significantly reduced.

[0094] The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions described in the above embodiments, or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, modification, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A modified epoxy resin material for underwater concrete structure repair, characterized in that: The invention comprises the following components by weight: 40-60 parts of epoxy resin matrix, 10-30 parts of water-reactive isocyanate curing agent, 1-5 parts of hydrophobic silane coupling agent, 2-8 parts of nano-scale silicon dioxide particles and 5-15 parts of flexible polyether modifier; the epoxy resin matrix is ​​prepared by reacting bisphenol A and epichlorohydrin in a molar ratio of 1:2-1:3 under alkaline conditions; the water-reactive isocyanate curing agent is one or both of hexamethylene diisocyanate and isophorone diisocyanate; and the hydrophobic silane coupling agent is γ-glycidyloxypropyltrimethoxysilane.

2. The modified epoxy resin material according to claim 1, characterized in that: The preparation method of the epoxy resin matrix comprises the following steps: mixing bisphenol A and epichlorohydrin in a molar ratio of 1:2-1:3, introducing nitrogen as a protective gas, reacting under alkaline conditions, and refluxing at 40-60° C. for 3-5 hours to obtain a crude product; and performing reduced pressure distillation and purification on the crude product at a temperature of 120-150° C. and a pressure of 0.1-1 kPa to obtain a bisphenol A type epoxy resin.

3. The modified epoxy resin material according to claim 2, characterized in that: The preparation method of the epoxy resin matrix comprises the following steps: (1) adding bisphenol A and epichlorohydrin in a molar ratio of 1:2-1:3 into a four-necked flask, and adding 50% sodium hydroxide aqueous solution to adjust the pH value to 10-12; (2) placing a reaction device in a constant temperature water bath, and connecting a mechanical stirrer, a thermometer, a reflux condenser and a nitrogen inlet pipe; (3) introducing nitrogen as a protective atmosphere at a flow rate of 2-3 bubbles / second, starting stirring, and rotating at a speed of 200-300rpm; (4) raising the reaction temperature to 40-60°C, maintaining the temperature range for reflux reaction for 3-5 hours, and obtaining a crude product; (5) transferring the crude product to a vacuum distillation device, and performing vacuum distillation and purification under the conditions of a temperature of 120-150°C and a pressure of 0.1-1kPa, to obtain a bisphenol A type epoxy resin.

4. The modified epoxy resin material according to claim 1, characterized in that: The modified epoxy resin material comprises the following components by weight: 45-55 parts of epoxy resin matrix, 16-30 parts of water-reactive isocyanate curing agent, 2-4 parts of hydrophobic silane coupling agent, 4-6 parts of nano-scale silicon dioxide particles, and 8-13 parts of flexible polyether modifier.

5. The modified epoxy resin material according to claim 1, characterized in that: The average particle size of the nano-scale silicon dioxide particles is 10-100 nm.

6. The modified epoxy resin material according to claim 1, characterized in that: The flexible polyether modifier is polyoxypropylene glycol, and its molecular weight is 1000-3000.

7. The method for preparing the modified epoxy resin material according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: (1) heating an epoxy resin matrix to 60-80° C. to melt the epoxy resin matrix, and sequentially adding a hydrophobic silane coupling agent, nano-sized silica particles and a flexible polyether modifier under stirring conditions, stirring for 30-60 minutes at a stirring rate of 100-300 rpm; (2) adding a water-reactive isocyanate curing agent, setting the stirring rate to 300-500 rpm, stirring for 2-5 minutes, and obtaining a mixture; and (3) placing the mixture in a vacuum degassing machine with a vacuum degree of 0.11 kPa for degassing for 5-10 minutes, thereby obtaining a modified epoxy resin material.

8. Use of the modified epoxy resin material according to any one of claims 1 to 5 in the repair of underwater concrete structures.

9. The use according to claim 7, characterized in that: The modified epoxy resin material is used as a repair material for the maintenance and emergency repair of underwater concrete structures; the underwater concrete structures include marine platforms, submarine pipelines, drilling facilities, submarine cables, bridges and docks.