Underground pipe network self-repairing coating material based on microcapsule technology and preparation method and construction method thereof

Abstract

The invention belongs to the technical field of pipe network repairing coatings, and particularly relates to an underground pipe network self-repairing coating material based on a microcapsule technology and a preparation method and a construction method thereof. The underground pipe network self-repairing coating material based on the microcapsule technology comprises the following components in percentage by weight: 35-50% of matrix resin, 8-15% of a curing agent, 10-22% of A type microcapsules, 4-10% of B type microcapsules, 8-18% of functional filler, 3-8% of anticorrosive pigment, 2-5% of an auxiliary agent and 5-15% of a solvent, wherein the matrix resin is epoxy resin, the curing agent is modified aliphatic amine, polyamide or phenolic aldehyde amine, the type A microcapsule comprises an epoxy repairing agent core material and a polyurethane-polyurea capsule wall, the type B microcapsule comprises an amine curing agent core material and a polyurethane-polyurea capsule wall, and the functional filler is nano SiO2, mica powder or glass flakes. The anticorrosive pigment is zinc phosphate, zinc molybdate or modified graphene, the auxiliary agent is a defoaming agent, a flatting agent, a coupling agent or a thixotropic agent, and the solvent is xylene, butanol or butyl acetate. The invention provides an underground pipe network self-repairing coating material based on a microcapsule technology as well as a preparation method and a construction method of the underground pipe network self-repairing coating material.

Description

Technical Field

[0001] This invention belongs to the field of pipeline repair coating technology, and specifically relates to self-healing coating materials for underground pipelines based on microcapsule technology, as well as their preparation and construction methods. Background Technology

[0002] During long-term service, underground pipe networks inevitably develop microcracks on their coating surfaces due to the combined effects of soil stress changes, media corrosion, temperature cycles, and microbial erosion. If these microcracks are not repaired promptly, they will gradually expand into macroscopic damage, ultimately leading to coating failure, pipe corrosion perforation, or structural destruction, resulting in leaks. This problem is particularly prominent in concrete sewage and rainwater pipes, which are exposed to harsh environments with high humidity and corrosive media (hydrogen sulfide, organic acids, etc.) for extended periods.

[0003] The existing technology has the following drawbacks: High structural complexity: The microvascular-microcapsule binary system requires the pre-design of the geometric topology network of microvasculars and is achieved through a multi-step composite process (prepreg preparation → layering and laying → molding and curing), which is cumbersome. This results in low production efficiency and makes it difficult to adapt to the on-site spraying / brushing construction method of pipeline network.

[0004] High temperature sensitivity: Existing fusion-bonded epoxy microcapsule coatings require segmented sintering and curing at 90–200℃, and the polyurea capsule walls are at risk of degradation at high temperatures; they are not suitable for in-situ repair of existing pipelines, and concrete pipes cannot withstand high temperatures.

[0005] Limitations of single-repair: Once the microcapsule system triggers repair, the repair agent at that location is exhausted, making it unable to cope with potential secondary damage; the service life of the coating is limited by the first repair.

[0006] Insufficient environmental adaptability: The capsule walls made of natural materials such as paraffin and gelatin are prone to water absorption and swelling or microbial degradation in humid underground environments, affecting the stability of microcapsules; the repair function is weakened during long-term storage and service.

[0007] Fluctuations in the ratio of repair agent to curing agent: When the two components are packaged separately, the randomness of microcapsule rupture makes it difficult to mix the repair agent and curing agent in the ideal stoichiometric ratio; incomplete curing or excessively fast curing speed leads to unstable performance of the repair layer.

[0008] There is a contradiction between capsule wall strength and trigger sensitivity: if the capsule wall is too thick, microcracks are difficult to trigger rupture, while if the capsule wall is too thin, it is easy to break prematurely during preparation and storage; the repair response is not timely or the storage stability is poor.

[0009] Weak adhesion to the pipeline substrate interface: The existing microcapsule surface is smooth, and the bonding with the coating resin substrate interface relies on physical interlocking and lacks chemical bonding; the microcapsule-substrate interface becomes a weak point in mechanical structure, affecting the overall performance of the coating.

[0010] Lack of dedicated solutions for concrete pipes: Existing self-healing coatings are mainly designed for metal pipes, and there is insufficient research on their compatibility with concrete substrates; making them difficult to apply to the field of drainage pipe network repair. Summary of the Invention

[0011] In order to solve the above-mentioned problems in the existing technology, the purpose of this invention is to provide a self-healing coating material for underground pipelines based on microcapsule technology, as well as its preparation method and construction method.

[0012] The technical solution adopted in this invention is as follows: The self-healing coating material for underground pipelines based on microencapsulation technology comprises the following components by weight percentage: 35-50% matrix resin, 8-15% curing agent, 10-22% type A microcapsules, 4-10% type B microcapsules, 8-18% functional filler, 3-8% anti-corrosion pigment, 2-5% additives, and 5-15% solvent; The matrix resin is epoxy resin, the curing agent is modified fatty amine, polyamide or phenolic amine, the type A microcapsule includes epoxy repair agent core material and polyurethane-polyurea capsule wall, the type B microcapsule includes amine curing agent core material and polyurethane-polyurea capsule wall, the functional filler is nano SiO2, mica powder or glass flakes, the anti-corrosion pigment is zinc phosphate, zinc molybdate or modified graphene, the additives are defoamer, leveling agent, coupling agent or thixotropic agent, and the solvent is xylene, butanol or butyl acetate.

[0013] As a preferred embodiment of the present invention, both the type A microcapsule and the type B microcapsule include a core material, a capsule wall, and a functional outer layer arranged sequentially from the inside to the outside; the core material of the type A microcapsule is a low-viscosity epoxy repair agent, the core material of the type B microcapsule is a modified amine curing agent, the capsule wall is a polyurethane-polyurea hybrid copolymer, and the functional outer layer is a silane coupling agent graft layer; the core material accounts for 85-92% of the microcapsule volume, the thickness of the capsule wall is 2-8 μm, and the thickness of the functional outer layer is 50-200 nm.

[0014] As a preferred embodiment of the present invention, the core material of the type A microcapsule comprises the following components by weight percentage: 55-70% main resin, 15-25% reactive diluent, 8-15% reactive diluent, 0.3-0.8% antioxidant, and 0.2-0.5% flow modifier; The main resin is bisphenol F diglycidyl ether, the reactive diluent is C12-14 aliphatic glycidyl ether, the reactive diluent is 1,4-butanediol diglycidyl ether, the antioxidant is 2,6-di-tert-butyl-4-methylphenol, and the flow modifier is polydimethylsiloxane.

[0015] As a preferred embodiment of the present invention, the core material of the type B microcapsule comprises the following components by weight percentage: 45-60% primary curing agent, 15-25% secondary curing agent, 3-8% accelerator, 15-25% plasticizer, and 2-5% coupling agent; The main curing agent is triethylenetetramine, the auxiliary curing agent is polyetheramine D-230, the accelerator is 2,4,6-tris(dimethylaminomethyl)phenol, the plasticizer is dibutyl phthalate, and the coupling agent is γ-aminopropyltriethoxysilane.

[0016] As a preferred embodiment of the present invention, the capsule wall comprises the following components in parts by weight: 100 parts isocyanate, 30-50 parts polyether polyol, 15-25 parts chain extender, and 0.05-0.2 parts catalyst. The isocyanate is diphenylmethane-4,4'-diisocyanate, the polyether polyol is polypropylene glycol, the chain extender is ethylenediamine, and the catalyst is dibutyltin dilaurate.

[0017] The preparation method of self-healing coating material for underground pipe networks based on microencapsulation technology includes the following steps: S1: Weigh the matrix resin, add solvent to dilute it, and stir evenly; S2: Add functional fillers and anti-corrosion pigments in sequence, and disperse at high speed; S3: Add type A microcapsules and stir at low speed; S4: Add type B microcapsules and stir at low speed; S5: Add curing agent and stir at low speed; S6: Add the additives, stir well, filter, and set aside for later use.

[0018] As a preferred embodiment of the present invention, the preparation of the type A microcapsule or type B microcapsule includes the following steps: Y1: Oil phase preparation: Mix the core material components evenly according to the formula ratio, add diphenylmethane diisocyanate, and stir to dissolve; Y2: Aqueous phase preparation: Dissolve polyvinyl alcohol in deionized water, then add polypropylene glycol and ethylenediamine; Y3: Emulsification and dispersion: The oil phase is slowly added to the aqueous phase and emulsified by shearing using a high-speed disperser; Y4: Interfacial polymerization reaction: The emulsion is transferred to a reactor and heated to carry out interfacial polymerization; Y5: Post-processing: cooling, filtration, washing, and ethanol washing; Y6: Surface functionalization modification: the dispersion medium is anhydrous ethanol; Y7: Drying.

[0019] The construction method of self-healing coating material for underground pipelines based on microencapsulation technology includes the following steps: T1: Substrate pretreatment: Pretreatment of metal pipes, pretreatment of concrete pipes; T2: Coating Application: Spraying pressure: 15-20 MPa for primer, 15-20 MPa for intermediate coat, and 12-18 MPa for top coat; Nozzle diameter: base coat 0.43~0.53mm, intermediate coat 0.43~0.53mm, top coat 0.38~0.48mm; Spraying distance: 25-35cm for primer, 25-35cm for intermediate coat, and 25-35cm for top coat; Wet film thickness: primer 120-150μm, intermediate coating 100-130μm, topcoat 80-100μm; Dry film thickness: 80-100 μm for the base coat, 70-90 μm for the intermediate coat, and 50-70 μm for the top coat.

[0020] As a preferred embodiment of the present invention, the metal pipe pretreatment in step T1 includes the following steps: Degreasing: solvent wiping or alkaline washing; Rust removal: sandblasting / shot blasting; Roughness: Rz40~80μm; Cleaning: compressed air blowing; Coating interval: within 4 hours after pretreatment.

[0021] As a preferred embodiment of the present invention, the concrete pipe pretreatment in step T1 includes the following steps: Cleaning: High-pressure water gun; Repair: Repair defects with polymer mortar; Drying: Natural drying or hot air drying; Interface treatment: Apply concrete interface agent; Curing: Apply after the interface agent is surface dry.

[0022] The beneficial effects of this invention are as follows: 1. A two-component microcapsule system for separate encapsulation and synchronous release of repair agent and curing agent: This invention encapsulates epoxy repair agent and amine curing agent in different microcapsules. By controlling the capsule wall thickness and mechanical properties of the two microcapsules to ensure that they have similar rupture thresholds (difference ≤15%), synchronous rupture and release are ensured under damage triggering. This allows the repair agent and curing agent to be mixed at the damaged site according to the designed stoichiometric ratio (epoxy group: active hydrogen = 1:0.8~1.2), solving the problem of difficult precise control of the two-component ratio in the prior art.

[0023] 2. Polyurethane-polyurea hybrid capsule wall material system and its preparation process: A polyurethane-polyurea hybrid material, formed by the interfacial polymerization of diphenylmethane diisocyanate (MDI), polyether polyol (PPG-400), and ethylenediamine (EDA), is used as the microcapsule wall. The polyurethane segments (30-50%) provide flexibility (elongation at break 150-350%) and compatibility with the core material, while the polyurea segments (50-70%) provide rigidity (tensile strength 25-45 MPa), water resistance (water absorption ≤1.5%), and resistance to chemical media. The synergistic effect of both components endows the capsule wall with excellent comprehensive properties, making it particularly suitable for underground, humid, and corrosive environments.

[0024] 3. Surface Functionalization Technology of Silane Coupling Agent: The surface of the microcapsules is modified by composite modification with γ-aminopropyltriethoxysilane (KH550) and γ-glycidoxypropyltrimethoxysilane (KH560) in a 1:1 mass ratio (total amount is 36% of the dry weight of the microcapsules), introducing amino and epoxy active functional groups into the surface of the microcapsules. These functional groups can chemically react with the coating matrix resin to form covalent bonds, increasing the bonding strength of the microcapsule-matrix interface from 1.2-1.8 MPa of physical interlocking to 3.5-5.0 MPa of chemical bonding.

[0025] 4. Hierarchical Response Design Based on Particle Size Gradient Distribution: Three microcapsules with different particle sizes (small 30-50 μm, medium 60-80 μm, and large 90-120 μm) were prepared by controlling the emulsification and dispersion speed (3000–8000 rpm) and distributed at different depths (surface, middle, and bottom layers) using a layered coating process. Different particle sizes correspond to different trigger thresholds and response crack width ranges, achieving differentiated and hierarchical responses to microcracks (5-30 μm), medium cracks (30-100 μm), and deep cracks (100-500 μm), endowing the coating with the ability to repeatedly repair (≥3 times).

[0026] 5. Adjustable Capsule Wall Thickness-Trigger Threshold Method: By adjusting the isocyanate monomer concentration (within a core-to-MDI mass ratio of 100:1528) and reaction time (within a 25-hour range) during the interfacial polymerization reaction, the capsule wall thickness can be precisely controlled and continuously adjusted within the range of 2–8 μm. A quantitative relationship between capsule wall thickness and rupture strength is established (rupture strength σ = 0.35t + 0.15, where t is the capsule wall thickness in μm and σ is the rupture strength in MPa), enabling targeted control of trigger sensitivity to meet the needs of different pipeline network application scenarios.

[0027] 6. Specialized formulation system for concrete drainage pipes: Developing a H2S corrosion-resistant formulation containing acid-resistant reinforcing components (812% glass flakes, 46% zinc molybdate) and a scouring-resistant formulation containing highly wear-resistant components (610% silicon carbide micropowder, 35% PTFE micropowder) to address the specific working conditions of concrete sewage and rainwater pipes. This enables the engineering application of self-healing coatings in drainage network repair. The accompanying concrete interface treatment technology ensures adhesion between the coating and the concrete substrate reaches 2.5–4.5 MPa. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the three-level structure of the intelligent microcapsule; Figure 2 This is a flowchart of the microcapsule preparation process; Figure 3 This is a particle size distribution curve of the microcapsules; Figure 4 This is a schematic diagram of the cross-section of the coating with a particle size gradient distribution; Figure 5 This is a schematic diagram of a tiered response and repair mechanism; Figure 6 This is a schematic diagram of the four-stage process of self-repair. Figure 7 This is a flowchart of the coating application process. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the invention can be combined with each other.

[0031] I. Overall Composition of the Technical Solution The self-healing coating material for underground pipe networks provided by this invention is composed of the following components: Table 1 shows the composition of the coating materials (by mass percentage).

[0032]

[0033] II. Structural Design of Smart Microcapsules The core innovation of this invention lies in the design of a smart microcapsule with a three-level structure of "core-shell-functional outer layer". Figure 1 This is a schematic diagram of the three-level structure of a smart microcapsule.

[0034] Table 2 shows the detailed parameters of the three-level structure.

[0035]

[0036] Table 3 shows the formulation of type A microcapsule core material (epoxy repair agent).

[0037]

[0038] Table 4 shows the physical properties of the core material of the repair agent.

[0039]

[0040] Table 5 shows the formulation of the core material for type B microcapsules (curing agent).

[0041]

[0042] Table 6 shows the physical properties of the curing agent core material.

[0043]

[0044] Table 7 shows the formulation of polyurethane-polyurea hybrid capsule walls.

[0045]

[0046] Table 8 shows the performance parameters of the capsule wall.

[0047]

[0048] III. Microcapsule Preparation Process Figure 2 This is a flowchart of the microcapsule preparation process.

[0049] 3.1 Preparation of Type A Microcapsules (Epoxy Repair Agent) Step 1 – Oil Phase Preparation Mix the core material components evenly according to the formula ratio, add diphenylmethane diisocyanate (MDI), and stir to dissolve.

[0050] Table 9 shows the process parameters for oil phase preparation.

[0051]

[0052] Step 2 – Aqueous Phase Preparation Polyvinyl alcohol (PVA) was dissolved in deionized water, and polypropylene glycol (PPG-400) and ethylenediamine (EDA) were added.

[0053] Table 10 shows the process parameters for the preparation of the aqueous phase.

[0054]

[0055] Step 3 – Emulsification and Dispersion The oil phase is slowly added to the aqueous phase, and shear emulsification is performed using a high-speed disperser.

[0056] Table 11 shows the process parameters for emulsification and dispersion.

[0057]

[0058] Step 4 – Interfacial Polymerization Reaction The emulsion was transferred to a reaction vessel and heated to carry out interfacial polymerization.

[0059] Table 12 shows the process parameters for the interfacial polymerization reaction.

[0060]

[0061] Step 5 – Post-processing Table 13 is the post-processing procedure table.

[0062]

[0063] Step 6 – Surface Functionalization Modification Table 14 shows the process parameters for surface functionalization modification.

[0064]

[0065] Step 7 – Drying Table 15 shows the drying process parameters.

[0066]

[0067] 3.2 Preparation of Type B Microcapsules (Curing Agent) The preparation process of type B microcapsules is basically the same as that of type A, with the main differences being the core material composition and adjustments to some process parameters.

[0068] Table 16 shows the differences in the preparation of type B microcapsules (curing agent).

[0069]

[0070] 3.3 Microcapsule Quality Testing Standards Table 17 shows the quality testing standards for microcapsules.

[0071]

[0072] Figure 3 Microcapsule particle size distribution curve IV. Principles of Particle Size Gradient Distribution Design Figure 4 This is a schematic diagram of the cross-section of the coating with a particle size gradient distribution. Figure 5 This is a schematic diagram of a graded response and repair mechanism.

[0073] This invention adopts the "hierarchical response" design concept: microcapsules of different sizes are distributed at different depths of the coating, corresponding to different degrees of damage response.

[0074] Table 18 shows the correspondence between particle size, trigger threshold, and distribution depth.

[0075]

[0076] Table 19 shows the proportions of microcapsules of various particle sizes (based on dry film coating).

[0077]

[0078] V. Self-repair mechanism Figure 6 This is a schematic diagram of the four-stage process of self-repair.

[0079] Table 20 shows the kinetic parameters of the repair process.

[0080]

[0081] Table 21 lists the effects of ambient temperature on curing time.

[0082]

[0083] VI. Coating Preparation and Application Methods Figure 7 This is a flowchart of the coating application process.

[0084] 6.1 Matrix Pretreatment Table 22 shows the pretreatment process for metal pipes.

[0085]

[0086] Table 23 is a table of pretreatment for concrete pipes.

[0087]

[0088] 6.2 Coating Preparation On-site ingredient preparation sequence: Step 1: Weigh the base resin → add solvent to dilute → stir evenly (5 min) Step 2: Add functional filler and anti-corrosion pigment in sequence → disperse at high speed (1500 rpm, 15 min) Step 3: Add type A microcapsules → stir at low speed (300 rpm, 5 min) Step 4: Add type B microcapsules → stir at low speed (300 rpm, 5 min) Step 5: Add curing agent → stir at low speed (300 rpm, 3 min) Step 6: Add additives → stir well → filter (100 mesh) → set aside for use Ingredient Notes: Do not stir at high speed (≤500rpm) after adding microcapsules to prevent breakage; after adding curing agent, the pot life is 4-6 hours at 25℃; the prepared coating should be used within the pot life.

[0089] 6.3 Coating Application Table 24 shows the construction environment requirements.

[0090]

[0091] Table 25 is the coating parameter table (airless spraying).

[0092]

[0093] Table 26 is a coating interval schedule.

[0094]

[0095] 6.4 Curing and Maintenance Table 27 shows the curing stages for solidification curing.

[0096]

[0097] VII. Coating Performance Indicators 7.1 Basic Physical Properties Table 28 is a table of basic physical properties.

[0098]

[0099] 7.2 Resistance to chemical media Table 29 shows the chemical resistance performance.

[0100]

[0101] 7.3 Self-healing performance Table 30 shows the self-healing performance.

[0102]

[0103] This invention is not limited to the above-described optional embodiments. Anyone can derive other various forms of products under the guidance of this invention. However, regardless of any changes made in their shape or structure, any technical solution that falls within the scope of the claims of this invention shall be protected by this invention.

Claims

1. A self-healing coating material for underground pipe networks based on microcapsule technology, characterized in that: It comprises the following components by weight percentage: matrix resin 35-50%, curing agent 8-15%, type A microcapsules 10-22%, type B microcapsules 4-10%, functional fillers 8-18%, anti-corrosion pigments 3-8%, additives 2-5%, and solvents 5-15%; The matrix resin is epoxy resin, the curing agent is modified fatty amine, polyamide or phenolic amine, the type A microcapsule includes epoxy repair agent core material and polyurethane-polyurea capsule wall, the type B microcapsule includes amine curing agent core material and polyurethane-polyurea capsule wall, the functional filler is nano SiO2, mica powder or glass flakes, the anti-corrosion pigment is zinc phosphate, zinc molybdate or modified graphene, the additives are defoamer, leveling agent, coupling agent or thixotropic agent, and the solvent is xylene, butanol or butyl acetate.

2. A microcapsule technology based self-healing coating material for underground pipe network according to claim 1 characterized in that: Both the type A and type B microcapsules comprise a core material, a capsule wall, and a functional outer layer arranged sequentially from the inside out. The core material of the type A microcapsule is a low-viscosity epoxy repair agent, while the core material of the type B microcapsule is a modified amine curing agent. The capsule wall is a polyurethane-polyurea hybrid copolymer, and the functional outer layer is a silane coupling agent graft layer. The core material accounts for 85-92% of the microcapsule volume, the capsule wall thickness is 2-8 μm, and the functional outer layer thickness is 50-200 nm.

3. A microcapsule technology based self-healing coating material for underground pipe network according to claim 2, characterized in that: The core material of the type A microcapsule comprises the following components by weight percentage: 55-70% main resin, 15-25% reactive diluent, 8-15% reactive diluent, 0.3-0.8% antioxidant, and 0.2-0.5% flow modifier; The main resin is bisphenol F diglycidyl ether, the reactive diluent is C12-14 aliphatic glycidyl ether, the reactive diluent is 1,4-butanediol diglycidyl ether, the antioxidant is 2,6-di-tert-butyl-4-methylphenol, and the flow modifier is polydimethylsiloxane.

4. The self-healing coating material for underground pipelines based on microencapsulation technology according to claim 2, characterized in that: The core material of the type B microcapsule comprises the following components by weight percentage: 45-60% primary curing agent, 15-25% secondary curing agent, 3-8% accelerator, 15-25% plasticizer, and 2-5% coupling agent; The main curing agent is triethylenetetramine, the auxiliary curing agent is polyetheramine D-230, the accelerator is 2,4,6-tris(dimethylaminomethyl)phenol, the plasticizer is dibutyl phthalate, and the coupling agent is γ-aminopropyltriethoxysilane.

5. The self-healing coating material for underground pipelines based on microencapsulation technology according to claim 2, characterized in that: The capsule wall comprises the following components in parts by weight: 100 parts isocyanate, 30-50 parts polyether polyol, 15-25 parts chain extender, and 0.05-0.2 parts catalyst; The isocyanate is diphenylmethane-4,4'-diisocyanate, the polyether polyol is polypropylene glycol, the chain extender is ethylenediamine, and the catalyst is dibutyltin dilaurate.

6. A method for preparing a self-healing coating material for underground pipe networks based on microencapsulation technology, used to prepare the self-healing coating material for underground pipe networks based on microencapsulation technology as described in any one of claims 1 to 5, characterized in that: Includes the following steps: S1: Weigh the matrix resin, add solvent to dilute it, and stir evenly; S2: Add functional fillers and anti-corrosion pigments in sequence, and disperse at high speed; S3: Add type A microcapsules and stir at low speed; S4: Add type B microcapsules and stir at low speed; S5: Add curing agent and stir at low speed; S6: Add the additives, stir well, filter, and set aside for later use.

7. The method for preparing the self-healing coating material for underground pipelines based on microencapsulation technology according to claim 6, characterized in that: The preparation of the type A or type B microcapsules includes the following steps: Y1: Oil phase preparation: Mix the core material components evenly according to the formula ratio, add diphenylmethane diisocyanate, and stir to dissolve; Y2: Aqueous phase preparation: Dissolve polyvinyl alcohol in deionized water, then add polypropylene glycol and ethylenediamine; Y3: Emulsification and dispersion: The oil phase is slowly added to the aqueous phase and emulsified by shearing using a high-speed disperser; Y4: Interfacial polymerization reaction: The emulsion is transferred to a reactor and heated to carry out interfacial polymerization; Y5: Post-processing: cooling, filtration, washing, and ethanol washing; Y6: Surface functionalization modification: the dispersion medium is anhydrous ethanol; Y7: Drying.

8. A construction method for a self-healing coating material for underground pipelines based on microencapsulation technology, using the self-healing coating material for underground pipelines based on microencapsulation technology as described in any one of claims 1 to 5, characterized in that: Includes the following steps: T1: Substrate pretreatment: Pretreatment of metal pipes, pretreatment of concrete pipes; T2: Coating Application: Spraying pressure: 15-20 MPa for primer, 15-20 MPa for intermediate coat, and 12-18 MPa for top coat; Nozzle diameter: base coat 0.43~0.53mm, intermediate coat 0.43~0.53mm, top coat 0.38~0.48mm; Spraying distance: 25-35cm for primer, 25-35cm for intermediate coat, and 25-35cm for top coat; Wet film thickness: primer 120-150μm, intermediate coating 100-130μm, topcoat 80-100μm; Dry film thickness: 80-100 μm for the base coat, 70-90 μm for the intermediate coat, and 50-70 μm for the top coat.

9. The construction method of the self-healing coating material for underground pipelines based on microencapsulation technology according to claim 8, characterized in that: In step T1, the pretreatment of the metal pipe includes the following steps: Degreasing: solvent cleaning or alkaline washing; Rust removal: sandblasting / shot blasting; Roughness: Rz40~80μm; Cleaning: Blow clean with compressed air; Coating interval: Apply coating within 4 hours after pretreatment.

10. The construction method of the self-healing coating material for underground pipelines based on microencapsulation technology according to claim 8, characterized in that: In step T1, the pretreatment of the concrete pipes includes the following procedures: Cleaning: High-pressure water gun; Repair: Repair defects with polymer mortar; Drying: air drying or hot air drying; Interface treatment: apply concrete interface agent; Curing: apply after the interface agent is surface dry.

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