CN-121988243-A - Self-repairing microcapsule with double-shell nested structure and preparation method and application thereof

Abstract

The invention provides a self-repairing microcapsule with a double-shell nested structure, and a preparation method and application thereof, and relates to the technical field of coatings. The preparation method comprises the steps of (1) mixing isocyanate monomer or prepolymer with a repairing agent to obtain an oil phase, dissolving an emulsifying agent in water to obtain an oil-in-water emulsion after homogenization treatment, adding polyalcohol and a catalyst to react at a certain temperature to obtain a single-shell microcapsule for encapsulating the repairing agent, and (2) dispersing the single-shell microcapsule in deionized water, adding urea formaldehyde prepolymer and resorcinol, adjusting pH, and reacting at a certain temperature to obtain the self-repairing microcapsule with a double-shell nested structure. Has excellent environmental stability, shearing resistance and reliable repairing performance.

Inventors

• ZHANG CHENGWEN
• ZHANG ZHI
• LI CHUNLING
• SUN SHUANGQING
• ZHANG YIWEI

Assignees

• 山东佰盛能源科技有限公司

Dates

Publication Date

20260508

Application Date

20260211

Claims (10)

1. 1. The preparation method of the self-repairing microcapsule with the double-shell nested structure is characterized by comprising the following steps of: (1) Mixing isocyanate monomer or prepolymer with repairing agent to obtain oil phase, dissolving emulsifier in water to obtain oil-in-water emulsion, homogenizing to obtain oil-in-water emulsion, adding polyol and catalyst to react at certain temperature to obtain single-shell microcapsule for encapsulating repairing agent; (2) Dispersing the single-shell microcapsule encapsulating the repairing agent in deionized water, adding urea formaldehyde prepolymer and resorcinol, adjusting pH, and reacting at a certain temperature to obtain the self-repairing microcapsule with a double-shell nested structure.
2. 2. The method of claim 1, wherein in step (1), the emulsifier is a modified montmorillonite.
3. 3. The preparation method according to claim 2, wherein the preparation method of the modified montmorillonite comprises the following steps: Adding montmorillonite into deionized water, and adding hexadecyl trimethyl ammonium bromide or octadecyl trimethyl ammonium chloride with the weight of 20-40wt% of montmorillonite at a certain temperature to obtain modified montmorillonite.
4. 4. The method according to claim 1, wherein the concentration of the emulsifier solution obtained by dissolving the emulsifier in water is 1-3wt%.
5. 5. The method according to claim 1, wherein in the step (2), the method for producing the urea formaldehyde prepolymer comprises the steps of: Adding urea into formaldehyde aqueous solution, dropwise adding triethanolamine, regulating pH, and reacting at a certain temperature to obtain urea formaldehyde prepolymer; Wherein the molar ratio of urea to formaldehyde is 1 (1.5-2.0).
6. 6. The preparation method according to claim 1, wherein the mass ratio of the urea formaldehyde prepolymer to the single shell microcapsule encapsulating the healing agent is 1 (2-5).
7. 7. The preparation method according to claim 1, wherein the mass ratio of the urea formaldehyde prepolymer to the resorcinol is 1 (10-30).
8. 8. The method of claim 1, wherein the isocyanate monomer or prepolymer is selected from one of TDI, MDI, HMDI, HDI or IPDI; And/or the repairing agent is any one or more of acrylic acid, vinyl monomer or silicon-based repairing agent; and/or the polyalcohol is one of ethylene glycol, 1, 4-butanediol or glycerol; and/or the catalyst is dibutyl tin dilaurate.
9. 9. A self-healing microcapsule of a double-shell nested structure prepared by the preparation method of any one of claims 1 to 8.
10. 10. Use of a self-healing microcapsule with a double shell nested structure according to claim 9 in a self-healing coating, wherein the self-healing microcapsule with a double shell nested structure is added to a coating and the resulting coating is applied to the surface of a metal substrate to form the self-healing coating.

Description

Self-repairing microcapsule with double-shell nested structure and preparation method and application thereof Technical Field The invention relates to the technical field of paint, in particular to a self-repairing microcapsule with a double-shell nested structure, and a preparation method and application thereof. Background The metal material is extremely easy to be corroded to fail in the service process, which not only causes huge economic loss, but also can cause serious safety accidents. The most common protective measure at present is the use of organic protective coatings, which rely mainly on barrier action to block the corrosive medium, thus slowing the corrosion process. However, during long-term use, the coating is inevitably subject to mechanical wear, scratches or environmental stresses to develop cracks and defects, through which the corrosive medium rapidly penetrates, thereby accelerating localized corrosion of the metal substrate. To solve the above problems, self-repairing protective coatings have become a research hotspot. Such coatings are capable of releasing a repair agent after damage occurs, filling and curing the crack area, thereby restoring the integrity and protective properties of the coating. Among them, microcapsule type self-repairing systems have been widely studied because of their flexible design and clear trigger response. Most of the prior researches rely on a bi-component catalytic system, namely, a repairing agent microcapsule and a catalyst are simultaneously introduced into a coating, wherein the catalyst is used for promoting the crosslinking and curing of the repairing agent in the self-repairing process, and when the coating is broken, the repairing agent is released and polymerized under the action of the catalyst. The system has higher repairing efficiency, but the preparation process is complex, the catalyst is expensive, the thermal stability is poor, the requirement on dispersion uniformity is strict, and engineering application is difficult to realize. On the other hand, it has been studied to use urea formaldehyde or polyurethane organic shell encapsulated vegetable oil as a repairing agent, and its synthetic process is relatively simple, but the shell strength is insufficient, the environmental stability is poor, and the self-repairing effect is limited due to early cracking or failure in the coating service process. The Chinese patent publication No. CN103881465A discloses a microcapsule for self-repairing coating, a preparation method and an application, wherein the microcapsule takes urea and formaldehyde as capsule wall components, fluorocarbon resin and epoxy resin are mixed as capsule core components, so that the microcapsule with the particle size ranging from 300um to 400um can be obtained, and the prepared microcapsule is mixed with water-based fluorocarbon coating for repairing the coating. The patent only depends on a urea resin single shell layer, lacks an outer layer reinforcing structure, is easily corroded by solvents or damaged by mechanical shearing force in the processes of mixing, coating and subsequent use, leads to early rupture of microcapsules, and leads to leakage failure of a repairing agent. The Chinese patent publication No. CN102702838B discloses a microcrack self-repairing microcapsule, which comprises a capsule core and a capsule wall, wherein the capsule core comprises, by weight, 10-60 parts of isocyanate derivatives, 0.1-10 parts of capsule core diluents and 2-40 parts of cosolvent, the capsule wall comprises, by mole ratio, urea..formaldehyde solution..prepolymer=1..0-4.0..2.0-6.0, and the prepolymer comprises, by mole ratio, 1:2.0-5.0:0.3-3.0 of isocyanate derivatives, cyclohexanone and chain extenders. Also disclosed is a microcrack self-healing corrosion-resistant coating using the capsule. The urea resin is modified by the isocyanate prepolymer to ensure that the polyurea shell layer has certain toughness, but the structure is still of a single-layer structure, the rigidity nature of the urea resin is in a certain contradiction with the toughness modification of the prepolymer, and high toughness and high hardness cannot be realized at the same time. The Chinese patent publication No. CN120137494A discloses a preparation method of a self-repairing coating based on microcapsules, the self-repairing coating and a light metal alloy. The preparation method of the self-repairing coating comprises the steps of adding microcapsules into a mixed solution of epoxy resin and a curing agent, stirring to obtain a coating, coating the coating on the surface of a substrate to obtain the self-repairing coating, wherein the microcapsule preparation step comprises the steps of preparing a prepolymer solution, the components of the prepolymer solution comprise urea and formaldehyde, preparing an oil-in-water emulsion, adding tung oil into a surfactant solution, emulsifying to obtain the oil-in-water emulsion, and mixing the prepolymer s