CN115418154A

CN115418154A - Self-warning and self-repairing functional coating based on porous microspheres and coating prepared from coating

Info

Publication number: CN115418154A
Application number: CN202211032311.7A
Authority: CN
Inventors: 罗静; 刘仁; 李伟; 陶俊杰
Original assignee: Jiangnan University
Current assignee: Jiangnan University
Priority date: 2022-08-26
Filing date: 2022-08-26
Publication date: 2022-12-02
Anticipated expiration: 2042-08-26
Also published as: CN115418154B

Abstract

The invention discloses a self-warning and self-repairing functional coating based on porous microspheres, which comprises porous microspheres loaded with fluorescent probes and corrosion inhibitors and film-forming resin, wherein the porous microspheres loaded with the fluorescent probes and the corrosion inhibitors account for 2-10wt% of the total mass of the coating; the porous microsphere loaded with the fluorescent probe and the corrosion inhibitor takes a polymer formed by photocuring a photopolymerisable material as a matrix, and the photopolymerisable material comprises 30-60wt% of photopolymerisable monomers, 1-3.5wt% of photoinitiators, 30-50wt% of organic solvents, 2-10wt% of fluorescent probes and 2-10wt% of corrosion inhibitors. The preparation method of the porous microsphere is simple and quick, no after-loading is needed, the porous microsphere is efficient and energy-saving, the compatibility with resin is good, and the prepared coating has the functions of self-warning and self-repairing.

Description

Self-warning and self-repairing functional coating based on porous microspheres and coating prepared from coating

Technical Field

The invention relates to the technical field of functional coatings, in particular to a self-warning and self-repairing functional coating based on porous microspheres and a coating prepared from the self-warning and self-repairing functional coating.

Background

Corrosion is a great threat to countries in the world and causes serious economic losses to the human society. Conventional coating protection techniques can effectively protect metal substrates, but over time, protective coatings tend to fail after prolonged exposure to corrosive environments or mechanical damage. Coating failure is a process that becomes quantitative to qualitative and such variations often do not match the inspection and maintenance cycles of the protected objects and structures. Furthermore, corrosion that occurs in areas that are relatively difficult to monitor or to cover with a coating is also difficult to perceive. If corrosion cannot be found in time, the spread of corrosion can cause more serious economic loss and safety accidents. Therefore, it is very important to sense the corrosion site at the initial stage of metal corrosion and to take effective measures in time.

The current corrosion sensing methods mainly comprise electrochemical methods, electromagnetic wave techniques, infrared thermal imaging, acoustic reflection and the like. However, most of them rely on expensive instruments and require testing and analysis by experimenters with high expertise, which presents a great obstacle to the practical application of these methods. The corrosion induction coating is an effective means for solving the problems, and the autonomous early warning of corrosion under the coating can be realized without external intervention.

Early designs of self-warning coatings generally relied on the corrosion sensing probe (e.g., metal ion or pH probe) to undergo a color or fluorescence change upon a change in pH that occurs during reaction or corrosion with the metal ion. The probes distributed in the coating can respond to changes in the corrosion environment (such as changes in pH, increases in metal ion concentration) at the corrosion site of the coating, thereby allowing monitoring of the corrosion phase of the coating. However, the direct incorporation of the probe into the coating substrate is not only susceptible to interference from other components in the coating, but also can destroy the integrity and compactness of the coating, which is detrimental to the corrosion protection of the coating.

In addition to autonomously perceiving damaged areas, smart coatings that can provide active corrosion protection are also important for repairing coating damage and extending the useful life of the coating. Therefore, to improve service life and achieve durable corrosion protection, it is more important to integrate corrosion sensing and active corrosion protection/repair properties into one coating system.

In order to integrate multiple functions into one coating, researchers have attempted to use two microspheres loaded with functional molecules and use them for corrosion sensing and active corrosion protection. For example, there are researchers using mesoporous silica for supporting corrosion sensing probes and active corrosion inhibitors, and although mesoporous silica has a large specific surface area and a high loading amount, the properties of the coating itself are affected due to poor dispersibility and compatibility of the inorganic container with the polymer coating matrix. Thus, the dispersibility and compatibility of the container with the polymer coating matrix and the effect on the performance of the base film of the coating are taken into account. Polymeric micro-containers are more suitable as loading containers than inorganic particles. The existing method for loading the polymer micro-container mainly comprises porous microspheres and microcapsules, and compared with the existing method, the porous microspheres can respond to local pH change of a corrosion area more quickly, so that the core material can be effectively released without being damaged, and the effects of early warning corrosion and inhibiting corrosion are achieved more quickly. However, at present, the preparation of porous polymer microspheres mostly adopts thermal polymerization, which has the problems of high energy consumption and environmental pollution, and there are few reports on documents for preparing porous microspheres by using a photopolymerization method; secondly, the porous microsphere-supported core material reported at present mostly uses a post-supporting method such as vacuum impregnation, and often requires long-time impregnation and a large amount of solvent. The problems of complicated preparation steps and low preparation efficiency exist.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a self-warning and self-repairing functional coating based on porous microspheres and a coating prepared from the coating. The preparation method of the porous microsphere is simple and rapid, no after-loading is needed, the porous microsphere is efficient and energy-saving, the compatibility with resin is good, and the prepared coating has the functions of self-warning and self-repairing.

The technical scheme of the invention is as follows:

a self-warning and self-repairing functional coating based on porous microspheres comprises porous microspheres loaded with fluorescent probes and corrosion inhibitors and film-forming resin, wherein the porous microspheres loaded with the fluorescent probes and the corrosion inhibitors account for 2-10wt% of the total mass of the coating;

in one embodiment, the porous microspheres loaded with the fluorescent probes and the corrosion inhibitor take a polymer formed by photo-curing a photo-polymerization material as a matrix, the particle size distribution of the porous microspheres loaded with the fluorescent probes and the corrosion inhibitor is 2-40 μm, the pore size distribution is 1-40nm, and the specific surface area is 15-300m ² /g；

The photo-polymerization material comprises 30-60wt% of photo-polymerization monomer, 1-3.5wt% of photoinitiator, 30-50wt% of organic solvent, 2.0-10wt% of fluorescent probe and 2.0-10wt% of corrosion inhibitor.

In one embodiment, the photopolymerizable monomer is one or more of 1, 6-hexanediol diacrylate, 3-hydroxy-2, 2-dimethylpropyl-3-hydroxy-2, 2-dimethylpropyl diacrylate, ethylene glycol dimethacrylate, tripropylene glycol diacrylate, triethylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate.

In one embodiment, the photoinitiator is one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-phenylbenzyl-2-dimethylamine-1- (4-morpholinobenzylphenyl) butanone, 1-hydroxycyclohexyl phenyl ketone, benzoin dimethyl ether, 2,4, 6-trimethylbenzoyl diphenyl phosphine oxide, isopropylthioxanthone, 4-chlorobenzophenone, 4' -dimethyldiphenyliodonium hexafluorophosphate, isooctyl p-dimethylaminobenzoate, 4-methylbenzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone,

ethyl

2,4, 6-trimethylbenzoylphenylphosphonate, 2-isopropylthioxanthone;

the organic solvent is one or more of alkane, aromatic hydrocarbon, ketone ether and carbonate solvents; preferably, the solvent is one or more of cyclohexane, toluene, xylene, methyl butanone and ethylene carbonate.

In one embodiment, the fluorescent probe is one or more of 8-hydroxyquinoline, quercetin, coumarin, lutein, 7-hydroxycoumarin, rhodamine B hydrazide, 5, 6-carboxyfluorescein, 5-acrylamide-1, 10 phenanthroline, bis [ N, N' -bis (rhodamine B) lactam-ethyl ] amine, spiro [ 1H-isoindole-1, 9- [9H ] xanthan gum ] -3 (2H) -1,3, 6-bis (diethylamine) -2- [ (1-methylethylenediamine) amino; the corrosion inhibitor is one or more of 8-hydroxyquinoline, benzotriazole, rhodamine B trap, mercaptobenzothiazole and methylbenzotriazole.

In one embodiment, 8-hydroxyquinoline serves as both a fluorescent probe and a corrosion inhibitor;

in one embodiment, when one or more of quercetin, coumarin, lutein, 7-hydroxycoumarin, rhodamine B hydrazide, 5, 6-carboxyfluorescein, 5-acrylamide-1, 10 phenanthroline, bis [ N, N' -bis (rhodamine B) lactam-ethyl ] amine, spiro [ 1H-isoindole-1, 9- [9H ] xanthan gum ] -3 (2H) -1,3, 6-bis (diethylamine) -2- [ (1-methylethylenediamine) amino is used as a fluorescent probe, a corrosion inhibitor is used together, and the corrosion inhibitor is one or more of 8-hydroxyquinoline, benzotriazole, rhodamine B trap, mercaptobenzothiazole and methylbenzotriazole.

In one embodiment, the preparation method of the porous microsphere loaded with the fluorescent probe and the corrosion inhibitor comprises the following steps: adding a photopolymerization material serving as an oil phase into a water phase containing a surfactant, emulsifying at a high speed by an emulsifying machine to obtain a stable emulsion, and carrying out photocuring, centrifugal washing and vacuum drying to obtain porous microspheres loaded with fluorescent probes and corrosion inhibitors; the volume ratio of the oil phase to the water phase is 1; preferably, the volume ratio of the oil phase to the water phase is 1.

In one embodiment, the mass fraction of the surfactant in the aqueous phase is 0.5-2wt%; the surfactant is one or more of polyvinyl alcohol, dodecyl phenol polyoxyethylene ether, octyl phenol polyoxyethylene ether-10, alkylphenol polyoxyethylene ether and polyoxyethylene sorbitan fatty acid ester.

In one embodiment, the conditions for high speed emulsification are: the emulsifying speed is 5000-20000rpm, and the emulsifying time is 1-5min.

In one embodiment, the conditions for photocuring are: the UV curing wavelength is 230-420nm, and the UV curing time is 5-20min.

In one embodiment, the film-forming resin is one or more of polyurethane resin, epoxy resin, acrylic resin, fluorocarbon resin, silicone resin, polyurethane acrylic resin, epoxy acrylic resin and polyester acrylate.

A coating prepared from a self-warning and self-repairing functional coating comprises the following steps: uniformly mixing 2-10wt% of porous microspheres loaded with fluorescent probes and corrosion inhibitors with film-forming resin, coating an organic coating on a metal plate, and curing to obtain the bifunctional coating with the self-warning and self-repairing functions.

In one embodiment, the curing mode of the coating is photocuring, and the coating uses the following paint formula: 2-10wt% of porous microspheres loaded with fluorescent probes and corrosion inhibitors, 50-70wt% of photocuring resin, 15-30wt% of reactive diluents, 2-4wt% of photoinitiators and 1-10wt% of auxiliaries;

the conditions of photocuring irradiation are as follows: the UV wavelength is 230-420nm, and the curing time is 0.5-2min.

In one embodiment, the light-cured resin is one or more of epoxy acrylate, polyurethane acrylate and polyester acrylate; the active diluent is one or more of tetrahydrofurfuryl acrylate, isobornyl acrylate, tetrahydrofuran acrylate and polyethylene glycol diacrylate; the auxiliary agent is one or more of an adhesion promoter and a flatting agent;

the adhesion promoter is one or more of methacrylated phosphate (CD 9051), 2-methyl-2-acrylic acid-2-hydroxyethyl phosphate (PM-1) and hydroxyethyl methacrylate phosphate (PM-2);

the leveling agent is polyether modified polydimethylsiloxane copolymer (BYK 333).

In one embodiment, the coating is cured by heat, and the coating formulation is: 2-10wt% of porous microspheres loaded with fluorescent probes and corrosion inhibitors, 90-98wt% of bi-component organic silicon resin, and accelerated curing in an oven at 60 ℃.

In one embodiment, the curing mode of the coating is normal temperature curing, and the formula of the coating is as follows: 2-10wt% of porous microspheres loaded with fluorescent probes and corrosion inhibitors and 90-98wt% of single-component alkyd resin, and the porous microspheres are placed at normal temperature for two days for curing.

The beneficial technical effects of the invention are as follows:

(1) The porous microsphere loaded with the fluorescent probe and the corrosion inhibitor is prepared by adopting a photopolymerization technology to replace the traditional thermal polymerization method, and has the advantages of simple process, quick preparation method and no need of heating at normal temperature.

(2) The traditional micro-nano container load probe usually adopts a post-load mode, needs a long-time dipping process and uses a large amount of solvent; in the invention, the loading of the probe and the preparation of the microsphere are carried out simultaneously, so that one step is realized, time and labor are saved, and various defects caused by a post-loading method are avoided.

(3) Compared with inorganic porous materials, the porous microspheres loaded with the fluorescent probes and the corrosion inhibitor have better compatibility with resin, the structure of the porous microspheres is adjustable, the compatibility between the microspheres and the resin can be further adjusted and controlled through the selection of the photopolymerization materials, and the negative influence on the mechanical property and the corrosion resistance of the coating caused by the addition of the microspheres is weakened.

(4) The coating prepared by the invention has double effects of self-warning and self-repairing, when the coating is damaged, the fluorescent probe is released from the porous microsphere and generates a complexing reaction with metal ions generated when a metal material is corroded to generate a macroscopic fluorescence change, so that the damage of the coating is indicated and the occurrence of metal corrosion is warned; meanwhile, the corrosion inhibitor is released from the porous microspheres, so that the further progress of corrosion reaction can be inhibited, and the protective effect of the coating on the metal matrix can be maintained. Meanwhile, the experimental result shows that the addition of the porous microspheres has no obvious influence on the properties of the coating, such as hardness, adhesion and the like.

Drawings

FIG. 1 is a schematic diagram of a process for preparing porous microspheres obtained in example 1 of the present invention;

FIG. 2 is the release kinetics and loading capacity of porous microspheres with different addition amounts of 8-hydroxyquinoline prepared in example 1 of the present invention, and release curves under different pH conditions;

in the figure, the addition amounts of (a) 8-hydroxyquinoline are 2.4wt%, 4.7wt%, 6.9wt%, and 9.0wt%, respectively; (b) The release curve of the porous microspheres with the addition amount of the 8-hydroxyquinoline of 6.9wt% under different pH conditions;

FIG. 3 is a digital photograph of the functional coating prepared in example 1 of the present invention under visible light and UV lamp after salt spray treatment for various periods of time;

FIG. 4 is a photograph of the functional coating obtained in example 1 after scratching and salt spray treatment under an ultraviolet lamp for different periods of time;

FIG. 5 is an electrochemical impedance spectroscopy of a coating layer of varnish, directly doped with 8-hydroxyquinoline and doped with porous microspheres of example 1 of the present invention for 35 days (3.5 wt% NaCl aqueous solution);

FIG. 6 is a schematic diagram of a self-warning and self-repairing mechanism of the coating prepared in embodiment 1 of the present invention;

FIG. 7 is an electron micrograph of porous microspheres obtained in example 2 of the present invention;

FIG. 8 is a microscope photograph of the depth of field of the coating with different amounts of porous microspheres uniformly dispersed therein in example 3 of the present invention (the dimensions are 20 μm).

Detailed Description

The invention is described in detail below with reference to the figures and examples.

Example 1

A self-warning and self-repairing functional coating based on porous microspheres is prepared by the following steps:

(1) Preparation of porous microspheres loaded with fluorescent probes and corrosion inhibitors

Referring to FIG. 1, 0.1g of fluorescent probe 8-hydroxyquinoline, 2g of trimethylolpropane triacrylate, 2g of toluene, and 0.06g of 2-hydroxy-2-methyl-1-phenyl-1-propanone were weighed out as oil phases and mixed by ultrasound. According to the oil phase: water phase =1:5, adding the mixture into 20mL of polyvinyl alcohol aqueous solution (2 wt%), emulsifying at a high speed of 10000rpm for 2min to obtain stable emulsion, curing by ultraviolet light (the wavelength is 365 nm) for 10min, and performing centrifugal washing and vacuum drying to obtain the porous microspheres loaded with 8-hydroxyquinoline. Porous microspheres (2.4 wt%, 4.7wt%, 6.9wt%, 9.0wt%, respectively) were prepared with different amounts of 8-hydroxyquinoline, varying the amount of 8-hydroxyquinoline used, to 0.2g, 0.3g, and 0.4g, respectively.

(2) Preparation of functional coatings

Weighing 3g of epoxy acrylate, 4g of polyester acrylate, 2.3g of tetrahydrofurfuryl acrylate, 0.3g of 2-hydroxy-2-methyl-1-phenyl-1-acetone, 0.1g of a leveling agent BYK333, 0.3g of an adhesion promoter PM-1 and 0.75g of the porous microsphere (with the addition of 6.9 wt%) loaded with 8-hydroxyquinoline prepared in the step (1), performing ball milling dispersion at 3000rpm for 2min, coating the porous microsphere on the surface of the aluminum alloy, and performing UV curing (with the wavelength of 365 nm) for 1min to obtain the self-warning and self-repairing dual-functional coating based on the porous microsphere.

Example 2

Weighing 0.3g of 8-hydroxyquinoline, 2g of 1, 6-hexanediol diacrylate, 2g of toluene and 0.06g of 2-hydroxy-2-methyl-1-phenyl-1-acetone as oil phases, and ultrasonically mixing uniformly. According to the oil phase: water phase =1: adding 40mL of polyvinyl alcohol aqueous solution according to the proportion of 10, emulsifying at a high speed of 15000rpm for 2min to obtain stable emulsion, curing by ultraviolet light for 10min, centrifuging, washing, and drying in vacuum to obtain the porous microspheres loaded with 8-hydroxyquinoline. The scanning electron micrograph thereof is shown in FIG. 7, in which a clearly apparent porous structure is seen.

(2) Preparation of functional coatings

Weighing 10g of Cheng jump SY-3306L double-component transparent organic silicon resin (the mass ratio of the component A to the component B =10: 1) (Dongguan Cheng jump electronic material Co., ltd.) and 0.75g of the porous microspheres loaded with 8-hydroxyquinoline prepared in the step (1), performing ball milling dispersion at 2500rpm for 3min, coating the porous microspheres on the surface of an aluminum alloy, and performing heat curing in a 60 ℃ oven to obtain the self-warning and self-repairing dual-functional coating based on the porous microspheres.

Example 3

Weighing 0.1g of coumarin, 0.2g of mercaptobenzothiazole, 2g of tripropylene glycol diacrylate, 2g of toluene and 0.06g of 2-hydroxy-2-methyl-1-phenyl-1-acetone as oil phases, and uniformly mixing by ultrasound. According to the oil phase: water phase =1:5, adding the mixture into 20mL of a dodecylphenol polyoxyethylene ether aqueous solution (2 wt%), emulsifying at a high speed of 10000rpm for 3min to obtain a stable emulsion, curing by ultraviolet light for 15min, centrifuging, washing, and drying in vacuum to obtain the porous microspheres loaded with coumarin and mercaptobenzothiazole.

(2) Preparation of functional coatings

Weighing 10g of Lanling WC04-42 water-based alkyd resin (Jiangsu Lanling high polymer materials Co., ltd.), adding 0g,0.25g,0.5g,0.75g and 1g of the prepared porous microspheres, performing ball milling dispersion, coating the porous microspheres on the surface of the aluminum alloy, and curing at normal temperature for 2 days to obtain the self-warning and self-repairing dual-functional coating based on the porous microspheres. FIG. 8 is a microscope photograph of the prepared super-depth of field with different amounts of added porous microspheres uniformly dispersed in the coating.

Example 4

Referring to FIG. 1, 0.3g of fluorescent probe 8-hydroxyquinoline, 2g of tripropylene glycol diacrylate, 2g of toluene and 0.06g of 1-hydroxycyclohexyl phenyl ketone are weighed out as oil phases and mixed by ultrasound. According to the oil phase: water phase =1:5, adding the mixture into 20mL of a dodecyl phenol polyoxyethylene ether aqueous solution (2 wt%), emulsifying at a high speed of 10000rpm for 2min to obtain a stable emulsion, curing by ultraviolet light (the wavelength is 365 nm) for 10min, centrifuging, washing, and drying in vacuum to obtain the porous microspheres loaded with 8-hydroxyquinoline.

(2) Preparation of functional coatings

Weighing 3g of epoxy acrylate, 4g of polyester acrylate, 2.3g of polyethylene glycol diacrylate, 0.3g of 1-hydroxycyclohexyl phenyl ketone, 0.1g of a leveling agent BYK333, 0.3g of an adhesion promoter PM-1 and 0.8g of the 8-hydroxyquinoline-loaded porous microspheres prepared in the step (1) (the addition amount is 6.9 wt%), performing ball milling dispersion at 3000rpm for 2min, coating the porous microspheres on the surface of the aluminum alloy after ball milling dispersion, and performing UV curing (the wavelength is 365 nm) for 1min to obtain the self-warning and self-repairing dual-functional coating based on the porous microspheres.

Example 5

Referring to FIG. 1, 0.4g of fluorescent probe 8-hydroxyquinoline, 2g of trimethylolpropane triacrylate, 2g of toluene, and 0.06g of 2-hydroxy-2-methyl-1-phenyl-1-propanone were weighed out as oil phases and mixed by ultrasound. According to the oil phase: water phase =1:5, adding the mixture into 20mL of polyvinyl alcohol aqueous solution (2 wt%), emulsifying at a high speed of 10000rpm for 2min to obtain stable emulsion, curing by ultraviolet light (the wavelength is 365 nm) for 10min, and performing centrifugal washing and vacuum drying to obtain the porous microspheres loaded with 8-hydroxyquinoline.

(2) Preparation of functional coatings

Weighing 3g of epoxy acrylate, 4g of polyester acrylate, 2.3g of tetrahydrofuran acrylate, 0.3g of 2-hydroxy-2-methyl-1-phenyl-1-acetone, 0.1g of a flatting agent BYK333, 0.3g of an adhesion promoter CD9051 and 0.75g of the porous microsphere (with the addition of 9.0 wt%) loaded with 8-hydroxyquinoline prepared in the step (1), performing ball milling dispersion at 3000rpm for 2min, coating the porous microsphere on the surface of the aluminum alloy, and performing UV curing (with the wavelength of 365 nm) for 1min to obtain the self-warning and self-repairing dual-functional coating based on the porous microsphere.

Test example:

(1) Release and loading capacity;

15mg of porous microspheres prepared with different addition amounts of 8-hydroxyquinoline prepared in the step (1) of example 1 were weighed, 10mL of deionized water was added to disperse the porous microspheres, the porous microspheres were placed in a dialysis bag and then in a beaker containing 150mL of deionized water, the mixture was stirred at 200rpm, 3mL of dialysate was taken at regular intervals to measure the UV absorbance, and the loading amount of 8-hydroxyquinoline was quantified, with the results shown in FIG. 2 a.

As can be seen from FIG. 2a, as the addition amount of 8-hydroxyquinoline gradually increases, the amount of the loaded 8-hydroxyquinoline gradually increases and finally becomes stable, indicating that the loading amount can be easily adjusted according to the addition amount of 8-hydroxyquinoline.

Weighing 15mg of 6.9wt% group of 8-hydroxyquinoline-loaded porous microspheres prepared in the step (1) of example 1, adding 10mL of deionized water to disperse the porous microspheres, placing the porous microspheres in a dialysis bag, then placing the bag in a beaker containing 150mL of deionized water, adjusting the pH value by using hydrochloric acid and a sodium hydroxide aqueous solution, stirring the solution at 200rpm, taking 3mL of dialysate at regular intervals, measuring ultraviolet absorbance, and calculating the release amount of 8-hydroxyquinoline; the result is shown in fig. 2b, and it can be seen from fig. 2b that the porous microspheres are released more quickly under the acidic condition, which is beneficial to the quicker release of the fluorescent probe and the corrosion inhibitor under the acidic condition of the corrosive anode, and the more efficient early warning efficiency and repair efficiency are achieved.

(2) Early warning feature

The functional coating prepared in example 1 is placed in a neutral salt fog box, and the phenomena under visible light and an ultraviolet lamp are observed at different times, and the result is shown in fig. 3, as can be seen from fig. 3, the functional coating has fluorescence points under the ultraviolet lamp of 48h, the fluorescence gradually becomes stronger along with the time, and no obvious phenomenon is observed under the visible light. Obvious corrosion rust spots appear at the previous fluorescent points under visible light observation at 120h, which shows that the coating has excellent early warning capability on early corrosion;

fig. 4 shows photographs under an ultraviolet lamp after the functional coating prepared in example 1 of the present invention and the coating without the porous microspheres are scratched and subjected to salt spray treatment for different periods of time, and it can be seen from fig. 4 that the functional coating with the porous microspheres has an obvious fluorescence phenomenon at the scratched position, indicating that the bifunctional coating of the present invention has an excellent early warning effect on pitting corrosion and scratches.

(3) Self-healing feature

FIG. 5 shows the electrochemical impedance spectra after soaking the varnish (Control), the coating directly doped with 8-hydroxyquinoline (8-HQ) and the bifunctional coating prepared in example 1 (8-HQ @ pTMPTA) in a 3.5wt% NaCl solution for 35 days; as can be seen from FIG. 5, the impedance of the coating containing 8-hydroxyquinoline and porous microspheres is obviously increased in the first 14 days, which indicates that the functional coating has a certain corrosion inhibition and self-repair effect.

Fig. 6 is a schematic diagram of a self-warning and self-repairing mechanism of the coating prepared in embodiment 1 of the present invention, where the self-warning and self-repairing mechanism specifically includes: after the porous microspheres loaded with 8-hydroxyquinoline (serving as a fluorescent probe and a corrosion inhibitor simultaneously) are added into the coating, the release of the 8-hydroxyquinoline is accelerated in a corrosion anode region due to a local acidic environment, the 8-hydroxyquinoline and aluminum ions generated by corrosion are chelated to increase the planar rigid structure of the 8-hydroxyquinoline, so that the fluorescence efficiency is increased, the fluorescence enhancement effect is realized, and the fluorescence visualization of a corrosion region is realized under the irradiation of an ultraviolet lamp; meanwhile, 8-hydroxyquinoline as a corrosion inhibitor and a chelate of aluminum ions can be deposited on the surface of a metal substrate, and an adsorption layer is formed to block the permeation of a corrosion medium, so that the self-repairing corrosion inhibition effect is realized.

Claims

1. The self-warning and self-repairing functional coating based on the porous microspheres is characterized by comprising the porous microspheres loaded with fluorescent probes and corrosion inhibitors and film-forming resin, wherein the porous microspheres loaded with the fluorescent probes and the corrosion inhibitors account for 2-10wt% of the total mass of the coating;

the porous microspheres loaded with the fluorescent probes and the corrosion inhibitor take a polymer formed by photo-curing a photo-polymerization material as a matrix, the particle size distribution of the porous microspheres loaded with the fluorescent probes and the corrosion inhibitor is 2-40 mu m, the pore size distribution is 1-40nm, and the specific surface area is 15-300m ² /g；

The photo-polymerization material comprises 30-60wt% of photo-polymerization monomers, 1-3.5wt% of photo-initiators, 30-50wt% of organic solvents, 2-10wt% of fluorescent probes and 2-10wt% of corrosion inhibitors.

2. The self-warning and self-repairing functional coating as claimed in claim 1, wherein the photopolymerizable monomer is one or more of 1, 6-hexanediol diacrylate, 3-hydroxy-2, 2-dimethylpropyl-3-hydroxy-2, 2-dimethylpropyl diacrylate, ethylene glycol dimethacrylate, tripropylene glycol diacrylate, triethylene glycol dimethacrylate, trimethylolpropane triacrylate, and trimethylolpropane trimethacrylate.

3. The self-warning and self-repairing functional coating according to claim 1, wherein the photoinitiator is one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-phenylbenzyl-2-dimethylamine-1- (4-morpholinylbenzyl phenyl) butanone, 1-hydroxycyclohexyl phenyl ketone, benzoin dimethyl ether, 2,4, 6-trimethylbenzoyldiphenylphosphine oxide, isopropylthioxanthone, 4-chlorobenzophenone, 4' -dimethyldiphenyliodonium salt hexafluorophosphate, isooctyl p-dimethylaminobenzoate, 4-methylbenzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, ethyl 2,4, 6-trimethylbenzoylphenylphosphonate, and 2-isopropylthioxanthone; the organic solvent is one or more of alkane, aromatic hydrocarbon, ketone ether and carbonate solvent.

4. The self-warning and self-repairing functional coating as claimed in claim 1, wherein the fluorescent probe is one or more of 8-hydroxyquinoline, quercetin, coumarin, lutein, 7-hydroxycoumarin, rhodamine B hydrazide, 5, 6-carboxyfluorescein, 5-acrylamide-1, 10 phenanthroline, bis [ N, N' -bis (rhodamine B) lactam-ethyl ] amine, spiro [ 1H-isoindole-1, 9- [9H ] xanthan gum ] -3 (2H) -1,3, 6-bis (diethylamine) -2- [ (1-methylethylenediamine) amino; the corrosion inhibitor is one or more of 8-hydroxyquinoline, benzotriazole, rhodamine B trap, mercaptobenzothiazole and methylbenzotriazole.

5. The self-warning and self-repairing functional coating of claim 1, wherein the preparation method of the porous microspheres loaded with the fluorescent probes and the corrosion inhibitor comprises the following steps: adding a photo-polymerization material serving as an oil phase into a water phase containing a surfactant, emulsifying at a high speed by an emulsifying machine to obtain a stable emulsion, and carrying out photocuring, centrifugal washing and vacuum drying to obtain porous microspheres loaded with a fluorescent probe and a corrosion inhibitor; the volume ratio of the oil phase to the water phase is 1.

6. The self-warning and self-repairing functional coating as claimed in claim 5, wherein the mass fraction of the surfactant in the aqueous phase is 0.5-2wt%; the surfactant is one or more of polyvinyl alcohol, dodecyl phenol polyoxyethylene ether, octyl phenol polyoxyethylene ether-10, alkylphenol polyoxyethylene ether and polyoxyethylene sorbitan fatty acid ester.

7. The self-warning and self-repairing functional coating of claim 5, wherein the conditions of high-speed emulsification are as follows: the emulsifying speed is 5000-20000rpm, and the emulsifying time is 1-5min.

8. The self-warning and self-repairing functional coating of claim 5, wherein the photocuring conditions are as follows: the UV curing wavelength is 230-420nm, and the UV curing time is 5-20min.

9. The self-warning and self-repairing functional coating of claim 1, wherein the film-forming resin is one or more of polyurethane resin, epoxy resin, acrylic resin, fluorocarbon resin, silicone resin, polyurethane acrylic resin, epoxy acrylic resin, and polyester acrylate.

10. A coating prepared from the self-warning and self-repairing functional coating of claim 1, wherein the preparation method of the coating comprises the following steps: uniformly mixing 2-10wt% of porous microspheres loaded with fluorescent probes and corrosion inhibitors with film-forming resin, coating a layer of organic coating on a metal plate, and curing to obtain the bifunctional coating with the self-warning and self-repairing functions.