Moisture curing self-repairing microcapsule-epoxy resin composite coating as well as preparation method and application thereof
By preparing the moisture-cured self-healing microcapsules of the core-shell structure, the problem of microcapsules' limited load and failure under extreme conditions is solved, and catalyst-free self-healing and dielectric properties are maintained.
Patent Information
- Application Number
- CN202510245145.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-04
- Publication Date
- 2025-07-18
AI Technical Summary
The existing microcapsule repair agent has limited loading, which is prone to failure under extreme conditions, and requires catalyst triggering, so the self-repair effect is not ideal.
A thioureaethylene prepolymer with reactive isocyanate groups was synthesized using 3,6-dithialyl-1,8-octylthiotan and hexamethylenediisocyanate to prepare moisture-cured self-healing microcapsules of core-shell structures, and mixed with epoxy resin to form a self-healing composite coating.
Microcapsules spontaneously rupture during damage, and cross-link and polymerize with water molecules without catalysts, achieving independent repair, maintaining the dielectric properties of the coating and extending service life.
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Figure CN120325201A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of intelligent materials, and particularly relates to a moisture-curing self-healing microcapsule-epoxy resin composite coating, a preparation method thereof, and an application thereof. Background Art
[0002] Epoxy resin coatings are widely used in many industrial production fields. However, with the extension of service time, the coatings often face aging problems, which affect their performance and further lead to problems such as corrosion and damage of the substrate. The main reasons for coating aging include the influence of external environments such as ultraviolet radiation, high temperature, mechanical stress, and chemical corrosion. These factors will cause structural changes and functional degradation of the coatings. Especially under some extreme conditions, such as marine environments and chemical industries, the deterioration rate of the coatings is faster, resulting in early failure of equipment and materials.
[0003] Self-healing coatings can automatically restore the failed part when the coating is damaged due to mechanical damage or environmental factors, extending the service life of the coating. The research directions of self-healing technologies mainly include physical repair, chemical repair, and biological repair, etc. As a chemical repair technology among them, the microcapsule repair method has become the focus of research due to its good repair effect and relatively mature technical route.
[0004] The microcapsule repair method is a technology that encapsulates a repair agent in microcapsules. These microcapsules can release the repair agent when the coating is damaged, realizing automatic repair of the coating. The core principle of the microcapsule repair technology is that after the coating is damaged by external forces, the microcapsules rupture and release the pre-encapsulated repair substances. These repair substances can carry out chemical reactions at the damaged part of the coating, repair the damaged part, and restore the integrity of the coating.
[0005] However, at present, microcapsules still face some challenges and deficiencies. First, the loading capacity of common microcapsule repair agents is limited at present, resulting in that their repair effects may not reach the ideal effect in some larger or deeper cracks. Second, the coating may be affected by extreme conditions such as high temperature and acid-base environments during use, which will cause premature rupture or failure of the microcapsules, thus affecting the repair performance of the coating. In addition, the triggering conditions for self-healing are relatively complex and often require a catalyst. Summary of the Invention
[0006] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part, the abstract of the specification, and the title of the invention of the present application to avoid obscuring the purpose of this part, the abstract of the specification, and the title of the invention. However, such simplifications or omissions shall not be used to limit the scope of the present invention.
[0007] In view of the above problems and / or those existing in the prior art, the present invention is proposed.
[0008] Therefore, the object of the present invention is to overcome the deficiencies in the prior art and provide a moisture-curing self-healing microcapsule-epoxy resin composite coating, its preparation method and application.
[0009] To solve the above technical problems, the present invention provides the following technical solution: A preparation method of a moisture-curing self-healing microcapsule, characterized in that it includes,
[0010] Synthesize a thiourethane prepolymer with reactive isocyanate groups from 3,6-dithia-1,8-octanedithiol and hexamethylene diisocyanate;
[0011] Dissolve gum arabic in deionized water and stir to obtain an arabic solution;
[0012] Dissolve the thiourethane prepolymer with reactive isocyanate groups in chlorobenzene, add isophorone diisocyanate dropwise to obtain a mixture, add the mixture to the arabic solution, heat and stir, then add a mercapto complex, raise the temperature and stir, stop heating, cool and stir, and then centrifuge and dry to obtain the moisture-curing self-healing microcapsule.
[0013] As a preferred embodiment of the preparation method of the present invention, wherein: the molar ratio of 3,6-dithia-1,8-octanedithiol to hexamethylene diisocyanate is 1:1 to 3.
[0014] As a preferred embodiment of the preparation method of the present invention, wherein: the molar ratio of the thiourethane prepolymer with reactive isocyanate groups to isophorone diisocyanate is 2:1.5 to 2.9.
[0015] As a preferred embodiment of the preparation method of the present invention, wherein: the mercapto complex includes 3,6-dithia-1,8-octanedithiol, trimethylolpropane trimercaptopropionate, and pentaerythritol tetrakis(3-mercaptopropionate).
[0016] As a preferred embodiment of the preparation method of the present invention, wherein: the molar ratio of 3,6-dithia-1,8-octanedithiol, trimethylolpropane trimercaptopropionate, and pentaerythritol tetrakis(3-mercaptopropionate) in the mercapto complex is 5 to 7:4 to 6:1 to 4.
[0017] As a preferred embodiment of the preparation method of the present invention, wherein: the microcapsule has a core-shell structure, wherein the core material is isophorone diisocyanate and the shell material is polythioxyethane.
[0018] Another object of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing a moisture-curing self-healing microcapsule-epoxy resin composite coating, which is characterized in that: it includes mixing E51 type epoxy resin, methylhexahydrophthalic anhydride curing agent, 2-4-6 phenol and moisture-curing self-healing microcapsules, evacuating and then pouring, and curing at a gradient high temperature for 2 h at 90 °C and 2 h at 110 °C, and washing with absolute ethanol to obtain the moisture-curing self-healing microcapsule-epoxy resin composite coating.
[0019] As a preferred embodiment of the preparation method of the present invention, wherein: the mass fraction of the moisture-curing self-healing microcapsules is 1-5 wt%.
[0020] Another object of the present invention is to overcome the deficiencies in the prior art and provide a high-performance electrical tree damage self-healing coating based on moisture-curing self-healing microcapsules prepared by a preparation method.
[0021] Another object of the present invention is to overcome the deficiencies in the prior art and provide an application of a high-performance electrical tree damage self-healing coating based on moisture-curing self-healing microcapsules in power energy equipment.
[0022] Advantages of the present invention:
[0023] The present invention prepares a kind of microcapsule that can spontaneously rupture when suffering from external damage to release the core material, and can crosslink and polymerize with external water molecules without a catalyst to complete the repair. After mixing it with epoxy resin to make a self-healing composite coating, it still has good dielectric properties; the moisture-induced curing self-healing microcapsules prepared by the present invention spontaneously rupture when damaged, release the core material, and crosslink and polymerize with water molecules without a catalyst to complete the repair. Mixing the capsules in epoxy resin to obtain a composite self-healing insulating coating basically does not change the electrical properties of the original coating, and at the same time can locate and autonomously repair mechanical and electrical damages, thus greatly improving the service life. Description of the drawings
[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative work, other drawings can also be obtained according to these drawings. Among them:
[0025] Figure 1 It is the morphology diagram of the microcapsules prepared in Example 1 of the present invention under an optical microscope.
[0026] Figure 2 It is the particle size distribution diagram of the microcapsules prepared in Example 1 of the present invention.
[0027] Figure 3 The thermogravimetric curve of the microcapsules prepared in Example 1 of the present invention.
[0028] Figure 4 The alternating current characteristic breakdown field strength diagram of the composite coating prepared in Example 1 of the present invention.
[0029] Figure 5 The mechanical damage repair effect diagram of the composite coating prepared in Example 1 of the present invention during use. Detailed implementation manners
[0030] To make the above objects, features and advantages of the present invention more obvious and understandable, the following will describe the detailed implementation manners of the present invention in conjunction with the embodiments of the specification.
[0031] In the following description, many specific details are set forth to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar promotions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.
[0032] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure or characteristic that can be included in at least one implementation manner of the present invention. The "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that excludes other embodiments.
[0033] Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commercially available. Details are shown in Table 1.
[0034] Table 1
[0035]
[0036] The performance test methods of the moisture-curing self-healing microcapsule-epoxy resin composite coatings prepared in the embodiments and comparative examples of the present invention are referred to:
[0037] 1. Thermal stability analysis
[0038] The thermal stability of the capsules was detected using a thermogravimetric analyzer of model TGA2 from METTLER TOLEDO. The test method was to take about 10 mg of microcapsules to make a sample and heat it at a heating rate of 50 °C / min.
[0039] 2. Test of average particle size
[0040] The prepared microcapsule samples were added to anhydrous ethanol, ultrasonically dispersed, and then added to a Mastersizer 2000 laser particle size analyzer for testing. Set the parameters and start the test. After the test, export the test data for analysis to obtain the average particle size of the microcapsules.
[0041] 3. Test of breakdown field strength
[0042] The capacity of the test transformer is 100 kVA / 100 kV, and the rate is 2 kV / s until the sample breaks down.
[0043] Samples with different microcapsule contents were each tested 20 times.
[0044] Example 1
[0045] This example provides a preparation method of a moisture-curing self-healing microcapsule-epoxy resin composite coating:
[0046] (1) Synthesis of thiourea ethane prepolymer:
[0047] Mix 20.17 g (0.12 mol) of hexamethylene diisocyanate (HDI) with 11.2 g (0.06 mol) of 3,6-dithia-1,8-octanedithiol (DODT). Heat the mixture in an oil bath to 130 °C and stir for 1 h, then remove the heating source and stir the mixture for another 3 h. The obtained thiourea ethane prepolymer (p-TUR) is a white viscous paste and is stored at 4 °C to avoid further polymerization.
[0048] (2) Synthesis of IPDI-filled polythiourea ethane microcapsules:
[0049] Dissolve 4.50 g of gum arabic in 30 ml of deionized water and stir for 3 h to obtain a gum arabic solution;
[0050] After dissolving 1 g of p-TUR in 1.33 g (0.012 mol) of chlorobenzene at 50 °C to obtain a clear solution of p-TUR, add 3.15 g (0.014 mol) of isophorone diisocyanate dropwise under stirring to obtain a mixture;
[0051] Slowly add the mixture to 10 ml of gum arabic solution, heat to 50 °C and stir (1000 rpm). Add the thiol complex (the thiol complex is a mixture of 2.13 g (0.012 mol) of 3,6-dioxaoctane-1,8-dithiol (DODT), 3.15 g (0.008 mol) of trimethylolpropane trithioglycolate (TTMP) and 2.82 g (0.006 mol) of pentaerythritol tetra(3-mercaptopropionate) (PETMP)) and raise the temperature of the mixture to 60 °C. After 1 hour, stir the mixture without heating for 1 h to avoid caking of the microcapsules. Centrifuge the microcapsule suspension and dry at 40 °C for 24 hours to remove moisture.
[0052] (3) Mix E51 type epoxy resin, methylhexahydrophthalic anhydride curing agent, and 2-4-6 phenol in a mass ratio of 100:85:2, stir magnetically at 60 °C until homogeneous, then incorporate 2 wt% of the microcapsules prepared above, conduct a 20-min vacuum treatment to remove air bubbles, and then start pouring. Subsequently, cure at 90 °C for 2 h and 110 °C for 2 h using the gradient high-temperature method. Wash and wipe with absolute ethanol to obtain the composite self-healing coating.
[0053] Example 2
[0054] The difference from Example 1 is that the mass fraction of the incorporated microcapsules in step (3) is 1 wt%, and the process of the remaining steps refers to Example 1 to obtain the composite coating of this example.
[0055] Example 3
[0056] The difference from Example 1 is that the mass fraction of the incorporated microcapsules in step (3) is 3 wt%, and the process of the remaining steps refers to Example 1 to obtain the composite coating of this example.
[0057] Example 4
[0058] The difference from Example 1 is that the mass fraction of the incorporated microcapsules in step (3) is 4 wt%, and the process of the remaining steps refers to Example 1 to obtain the composite coating of this example.
[0059] Example 5
[0060] The difference from Example 1 is that the mass fraction of the incorporated microcapsules in step (3) is 5 wt%, and the process of the remaining steps refers to Example 1 to obtain the composite coating of this example.
[0061] Comparative Example 1
[0062] The difference from Example 1 is that the mass fraction of the incorporated microcapsules in step (3) is 0 wt%, and the process of the remaining steps refers to Example 1 to obtain the coating of this comparative example.
[0063] Comparative Example 2
[0064] The difference between this comparative example and Example 1 lies in step (2). The mass of p-TUR added was adjusted to 0.8 g, and the rest of the preparation process was the same as that of Example 1, obtaining microcapsules and composite coatings.
[0065] Comparative Example 3
[0066] The difference between this comparative example and Example 1 lies in step (2). The mass of IPDI added was adjusted to 2.15 g, and the rest of the preparation process was the same as that of Example 1, obtaining microcapsules and composite coatings.
[0067] Comparative Example 4
[0068] The difference between this comparative example and Example 1 lies in step (2). DODT was not added to the thiol-based composite, and the rest of the preparation process was the same as that of Example 1, obtaining microcapsules and composite coatings.
[0069] Comparative Example 5
[0070] The difference between this comparative example and Example 1 lies in step (2). TTMP was not added to the thiol-based composite, and the rest of the preparation process was the same as that of Example 1, obtaining composite coatings and composite coatings.
[0071] Comparative Example 6
[0072] The difference between this comparative example and Example 1 lies in step (2). PETMP was not added to the thiol-based composite, and the rest of the preparation process was the same as that of Example 1, obtaining composite coatings and composite coatings.
[0073] Comparative Example 7
[0074] The difference between this comparative example and Example 1 is that the magnetic stirring temperature in step (3) was adjusted to 50 °C, and the rest of the preparation process was the same as that of Example 1, obtaining composite coatings.
[0075] Comparative Example 8
[0076] The difference between this comparative example and Example 1 is that the magnetic stirring temperature in step (3) was adjusted to 70 °C, and the rest of the preparation process was the same as that of Example 1, obtaining composite coatings.
[0077] Table 2
[0078]
[0079] As can be seen from Table 2, the doping amount of microcapsules in the resin is inversely proportional to the breakdown field strength. Among them, in Comparative Example 1, since no capsules were added, there is no such index.
[0080] From Figure 1It can be seen that the microcapsules are in a plump spherical shape, and there is a distinct boundary between the capsules and the external environment. Moreover, the microcapsules have good dispersibility, without adhesion and aggregation phenomena. From Figure 2 it can be seen that the diameters of the microcapsules are mainly distributed between 100 - 400 μm, and the average diameter is 262.69 μm. The prepared microcapsules have a complete core - shell structure, effectively achieving the encapsulation of the core material.
[0081] The results of the thermal stability test of the microcapsules are as Figure 3 shown. At about 103 °C, the crystal water remaining on the surface of the capsules gradually evaporates, and a small weight loss begins to occur; starting from 189 °C, the mass loss rate of the microcapsules significantly accelerates. The reason is that the shell material cannot withstand high temperatures and begins to crack, and the core material with a repair function begins to flow out and evaporate at this time. After 344 °C, the wall material begins to decompose and carbonize. This shows that the microcapsules have good heat resistance.
[0082] As Figure 4 shown, compared with pure epoxy resin, the breakdown field strength of the composite insulating coating doped with a small amount (not more than 2 wt%) of self - healing microcapsules hardly changes, and still maintains good dielectric properties.
[0083] Use a surgical scalpel to artificially create scratches to simulate the mechanical damage suffered by the composite insulating coating during use. After standing for a period of time, observe its healing effect as Figure 5 shown.
[0084] When the coating is mechanically damaged, it induces the rupture of the microcapsule wall to release the core material. Even without a catalyst, the core material can undergo a cross - linking polymerization reaction with water molecules, and finally fill the damaged area on the surface scratch flat to achieve self - healing performance.
[0085] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not restrictive. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the present invention.
Claims
1. A preparation method of a moisture-curing self-healing microcapsule, characterized in that: Including, Synthesizing a thiourethane prepolymer with reactive isocyanate groups from 3,6-dithia-1,8-octanedithiol and hexamethylene diisocyanate; Dissolving gum arabic in deionized water and stirring to obtain an arabic solution; Dissolving the thiourethane prepolymer with reactive isocyanate groups in chlorobenzene, adding isophorone diisocyanate dropwise to obtain a mixture, adding the mixture to the arabic solution, heating and stirring, then adding a mercapto complex, heating and stirring, stopping heating, cooling and stirring, and centrifuging and drying to obtain the moisture-curing self-healing microcapsules.
2. The preparation method according to claim 1, characterized in that: The molar ratio of 3,6-dithia-1,8-octanedithiol to hexamethylene diisocyanate is 1:1 to 3.
3. The preparation method according to claim 1, characterized in that: The molar ratio of the thiourethane prepolymer with reactive isocyanate groups to isophorone diisocyanate is 2:1.5 to 2.
9.
4. The preparation method according to claim 1, characterized in that: The mercapto complex is composed of 3,6-dithia-1,8-octanedithiol, trimethylolpropane trimercaptopropionate, and pentaerythritol tetra(3-mercaptopropionate).
5. The preparation method according to claim 4, characterized in that: The molar ratio of 3,6-dithia-1,8-octanedithiol, trimethylolpropane trimercaptopropionate, and pentaerythritol tetra(3-mercaptopropionate) in the mercapto complex is 5 to 7:4 to 6:1 to 4.
6. The moisture-curing self-healing microcapsules prepared by the preparation method according to claims 1 to 5, characterized in that: The microcapsules have a core-shell structure, where the core material is isophorone diisocyanate and the shell material is polythioxyethane.
7. A preparation method of a moisture-curing self-healing microcapsule-epoxy resin composite coating, characterized in that: Including, mixing E51 type epoxy resin, methylhexahydrophthalic anhydride curing agent, 2-4-6 phenol and the moisture-curing self-healing microcapsules described in claim 6, evacuating, pouring, curing at 90 °C for 2 h and at 110 °C for 2 h by gradient high-temperature method, and washing with absolute ethanol to obtain the moisture-curing self-healing microcapsule-epoxy resin composite coating.
8. The preparation method according to claim 7, characterized in that: The mass fraction of the moisture-curing self-healing microcapsules is 1 to 5 wt%.
9. A high-performance electric tree damage self-healing coating based on moisture-curing self-healing microcapsules prepared by the preparation method described in claims 7 to 8.
10. Application of the high-performance electric tree damage self-healing coating based on moisture-curing self-healing microcapsules as described in claim 9 in power energy equipment.