CN-121972100-A - Intelligent self-repairing polyurea microcapsule for metal corrosion protection and composite protective coating thereof

CN121972100ACN 121972100 ACN121972100 ACN 121972100ACN-121972100-A

Abstract

The invention belongs to the technical field of material science and corrosion protection, and particularly relates to an intelligent self-repairing polyurea microcapsule for metal corrosion protection and a composite protective coating thereof. The technical problem to be solved is that the shell strength and brittleness of the existing microcapsule are difficult to regulate and control in a synergistic way, the core material repairing agent causes activity loss due to side reaction in the interfacial polymerization process, and the microcapsule particle size distribution is uneven. The technical scheme includes that an oil phase containing a first isocyanate monomer and a second isocyanate monomer with higher reactivity is mixed with a dispersion liquid containing a solid particle stabilizer, the mixture is homogenized and emulsified to form Pickering emulsion, an aqueous solution of an amine curing agent is added, interfacial polymerization is carried out under the stirring condition, the first isocyanate monomer and the amine curing agent are subjected to interfacial polymerization preferentially to form a shell layer at an oil-water interface, the second isocyanate monomer is encapsulated in a microcapsule, and the self-repairing polyurea microcapsule is obtained through aftertreatment.

Inventors

HOU HONGBO
MENG FANBIN
YANG QIAN
LI TIAN
LIAO TINGHAO
GUO ZHONGQIU
LI XINRU
WANG YANAN

Assignees

西南交通大学

Dates

Publication Date: 20260505
Application Date: 20260323

Claims (10)

1. The preparation method of the self-repairing polyurea microcapsule is characterized by comprising the following steps of: Mixing an oil phase containing a first isocyanate monomer and a second isocyanate monomer with a dispersion liquid containing a solid particle stabilizer, and forming a Pickering emulsion through homogenizing and emulsifying, wherein the reactivity of the first isocyanate monomer is higher than that of the second isocyanate monomer; Adding an aqueous solution of an amine curing agent into the Pickering emulsion, carrying out interfacial polymerization reaction under the condition of stirring, leading the first isocyanate monomer to be polymerized with the amine curing agent at an oil-water interface in preference to the second isocyanate monomer to form a shell layer, encapsulating the second isocyanate monomer in the shell layer, and obtaining the self-repairing polyurea microcapsule through post-treatment.
2. The process of claim 1 wherein the first isocyanate monomer is toluene diisocyanate TDI, the second isocyanate monomer is isophorone diisocyanate IPDI, and the amine curing agent is diethylenetriamine DETA.
3. The preparation method of claim 2, wherein the mass ratio of TDI to IPDI is 1 (2-4).
4. The preparation method of the Pickering emulsion, according to claim 1, is characterized in that the solid particle stabilizer is hydrophobic nano silicon dioxide, the mass fraction of the solid particle stabilizer is 0.1% -1%, and the rotational speed of homogenizing emulsification is 3000-8000 rpm and the time is 3-10 minutes in the preparation process of the Pickering emulsion.
5. The preparation method according to claim 1, wherein the interfacial polymerization reaction is carried out at a temperature of 40-60 ℃, a stirring speed of 300-800 rpm, and a reaction time of 2-5 hours.
6. Self-healing polyurea microcapsules according to any one of claims 1 to 5.
7. A self-healing composite coating comprising a coating matrix resin and self-healing polyurea microcapsules according to claim 6 uniformly dispersed in the coating matrix resin.
8. The self-healing composite coating according to claim 7, wherein the coating matrix resin is an epoxy resin.
9. A method for preparing the self-repairing composite coating according to claim 8, which is characterized in that self-repairing polyurea microcapsules are dispersed in a solvent, mixed with coating matrix resin, added with a curing agent, degassed, coated on the surface of a substrate and cured.
10. A self-healing composite coating according to claim 7 for corrosion protection in metallic materials.

Description

Intelligent self-repairing polyurea microcapsule for metal corrosion protection and composite protective coating thereof Technical Field The invention belongs to the technical field of material science and corrosion protection, and particularly relates to an intelligent self-repairing polyurea microcapsule for metal corrosion protection and a composite protective coating thereof. Background In a severe service environment, microscopic damages (such as scratches and microcracks) on the surface of the material are difficult to avoid, and the accumulation of the damages can directly lead to the failure of the protective coating, so that a series of problems of matrix corrosion, material performance degradation and the like are caused, and the service lives of key parts and facilities are seriously shortened. The traditional coating maintenance method often depends on periodic manual inspection and external repair intervention, so that the cost is high, and real-time and autonomous protection of damage is difficult to realize. Therefore, the ability of the material to autonomously sense and repair damage, i.e. the development of intelligent self-repairing materials, has become a leading research direction in the fields of material science, polymer chemistry and corrosion protection. In many self-repairing strategies, microcapsule coated repairing agent technology is considered as one of the paths with the most application prospect because of flexible design, convenience in compounding with the existing coating system and direct and effective repairing mechanism. The core of the technology is that the liquid repairing agent is encapsulated in the micron-sized capsule and dispersed in the coating matrix, when the coating generates cracks, the cracked capsule releases the repairing agent, and the crack healing is realized through chemical reaction. However, the performance of the microcapsules in the prior art has a number of bottlenecks, on the one hand, the capsules need to have sufficient mechanical stability to withstand the stresses of the coating processing and the initial stages of service, and on the other hand, the capsules need to be sensitively triggered to rupture under specific damaging stresses. In addition, the activity retention and release efficiency of the restorative and the mechanical properties of the final cured product together determine the restoration effect. Therefore, how to synergistically optimize the particle size uniformity, shell strength and brittleness of the microcapsules and the activity retention of the core material through precise chemical design is a key technical problem to be solved in the current field. Disclosure of Invention The invention aims to solve the problems of insufficient self-repairing efficiency, slow response speed (difficult to realize quick healing in minute scale) and poor long-term protection reliability of a coating caused by poor dispersibility and low repairing agent release efficiency due to the fact that in the existing microcapsule self-repairing coating technology for metal corrosion protection, the shell strength and brittleness of a microcapsule are difficult to regulate and control in a synergistic manner (mechanical stability at the initial stage of coating processing/service and sensitive cracking property when microcrack triggering cannot be considered), a core material repairing agent (isocyanate) is lost due to side reaction in the traditional interfacial polymerization process, and the microcapsule particle size distribution is uneven. The invention adopts the following technical means to realize the purposes: The invention provides a preparation method of a self-repairing polyurea microcapsule, which comprises the following steps: Mixing an oil phase containing a first isocyanate monomer and a second isocyanate monomer with a dispersion liquid containing a solid particle stabilizer, and forming a Pickering emulsion through homogenizing and emulsifying, wherein the reactivity of the first isocyanate monomer is higher than that of the second isocyanate monomer; Adding an aqueous solution of an amine curing agent into the Pickering emulsion, carrying out interfacial polymerization reaction under the condition of stirring, leading the first isocyanate monomer to be polymerized with the amine curing agent at an oil-water interface in preference to the second isocyanate monomer to form a shell layer, encapsulating the second isocyanate monomer in the shell layer, and obtaining the self-repairing polyurea microcapsule through post-treatment. In the above scheme, the first isocyanate monomer is Toluene Diisocyanate (TDI), the second isocyanate monomer is isophorone diisocyanate (IPDI), and the amine curing agent is Diethylenetriamine (DETA). In the scheme, the mass ratio of TDI to IPDI is 1 (2-4). In the scheme, the solid particle stabilizer is hydrophobic nano silicon dioxide, the mass fraction is 0.1% -1%, and in the preparation process of the