CN115895317A - A hierarchical response self-warning anti-corrosion coating and its preparation method - Google Patents

Abstract

The invention belongs to the technical field of metal corrosion prevention, and particularly discloses a graded-response self-early-warning anticorrosive coating. The composite microcapsule is composed of a composite microcapsule loaded with a double chromogenic substance and polymer resin, the composite microcapsule is composed of a polymer capsule and mesoporous silica loaded with a corrosion response agent, and the polymer capsule comprises a shell layer and crystal violet lactone coated by the shell layer. The mass fraction of the composite microcapsule in the polymer resin is 1.5-15%. The mass ratio of the mesoporous silica to the polymer capsule in the composite microcapsule is 1:2-1. The mass fraction of crystal violet lactone in the polymer capsule is 10-30%, and the loading rate of the corrosion response agent in the mesoporous silica is 5-25%. The invention also discloses a preparation method of the graded response self-warning anticorrosive coating. The invention can respectively respond to the damage of the coating surface and the corrosion of the metal interface and can give early warning to different damage degrees of the coating/metal system.

Description

A hierarchical response self-warning anti-corrosion coating and its preparation method

technical field

The invention belongs to the technical field of metal anticorrosion, and in particular relates to a graded response self-warning anticorrosion coating and a preparation method thereof.

Background technique

Organic anti-corrosion coatings are prone to damage in complex service environments, thereby reducing the mechanical properties and barrier properties of the coatings. In addition, local defects will lead to the intrusion of corrosive media and trigger the corrosion reaction of the base metal, destroying the bond between the organic coating and the metal substrate, causing the coating to lose its protective effect on the metal and fail prematurely. Therefore, it is of great significance to timely find the damaged location of the coating material and the interface corrosion site, and effectively evaluate the service status of the coating to ensure the service safety and life of the coating/metal system.

In recent years, in order to solve the problem of early detection of coating damage, researchers have proposed the design idea of self-warning anti-corrosion coating. Based on the material composition and acid-base fluctuations in the local area during the metal corrosion process, the corrosion-responsive substances are introduced into the resin to obtain a self-warning composite coating. At the position where the coating is damaged, the corrosion-responsive substance undergoes a color reaction under the action of the local corrosion microenvironment to warn of the occurrence of corrosion. However, coating damage and failure is a gradual process involving multiple processes such as surface damage, interfacial corrosion, and coating peeling. A single early warning mechanism cannot effectively warn the damage status and damage degree of the coating.

Therefore, it is urgent to develop a self-warning intelligent coating that responds to coating surface damage or metal interface corrosion in order to realize real-time warning of the coating service process.

Contents of the invention

An object of the present invention is to provide a graded response self-warning anti-corrosion coating, which can effectively solve the problem that the prior art cannot effectively warn the damage status and damage degree of the coating.

In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is:

A graded response self-warning anti-corrosion coating, which is composed of composite microcapsules loaded with dual chromogenic substances and a polymer resin, the composite microcapsules are composed of polymer capsules and mesoporous silica loaded with a corrosion response agent, the The polymer capsule includes a shell and crystal violet lactone covered by the shell.

Further, the mass fraction of the composite microcapsules in the polymer resin is 1.5%-15%.

Further, the mass ratio of the mesoporous silica in the composite microcapsule to the polymer capsule is 1:2˜1:10.

Further, the diameter of the composite microcapsule is 2 μm to 15 μm, the mass fraction of crystal violet lactone in the polymer capsule is 10% to 30%, and the loading of the corrosion response agent in the mesoporous silica is The rate is 5% to 25%.

Further, the material of the shell layer is one or any two of polymethyl methacrylate, polycaprolactone, polystyrene, chitosan and ethyl cellulose.

Further, the corrosion response agent is phenolphthalein, fluorescein, thymol blue, p-nitrophenylazoresorcinol, 2,4-dihydroxy-4'-nitroazobenzene, o-phenanthroline and one of the hydroxyquinolines.

Further, the polymer resin is one of acrylic resin, polyurethane resin, epoxy resin and polyurea resin.

Another object of the present invention is to provide a method for preparing a graded response self-warning anti-corrosion coating, which can effectively solve the problem that the prior art cannot effectively warn the damage status and damage degree of the coating.

A method for preparing a graded response self-warning anticorrosion coating as described in the above embodiments, comprising the following steps:

S1. Dissolve the material of the shell layer and crystal violet lactone in dichloromethane at a mass ratio of 2:1 to 10:1, stir evenly and add dodecane with a concentration of 1 mg/mL to 3 mg/mL The sodium phenylbenzenesulfonate solution was stirred at a temperature of 30°C to 40°C for 10h to 30h, and centrifuged at a speed of 6000r/min to 8000r/min for 6min to 10min to obtain polymer capsules coated with crystal violet lactone;

S2. Dissolve the corrosion response agent and mesoporous silica in the ethanol solution at a mass ratio of 1:1 to 5:1, keep the pressure in an oven with a vacuum degree of -0.1MPa for 1h to 3h, and then place it at room temperature and Press down and stir mechanically for 5h-10h, and centrifuge to obtain mesoporous silica loaded with corrosion response agent;

S3. Disperse the polymer capsules coated with crystal violet lactone and the mesoporous silica loaded with corrosion response agent in a mass ratio of 1:2 to 1:10 in the sodium dodecylbenzenesulfonate solution, and stir , centrifugation to obtain composite microcapsules loaded with dual chromogenic substances;

S4. Add the composite microcapsules to the polymer resin and mix evenly, coat the surface of the steel or magnesium alloy material, and cure in an oven at 50°C to 80°C for 15h to 30h to obtain a graded response self-warning anti-corrosion coating.

The beneficial technical effect of the present invention is:

(1) The present invention mixes composite microcapsules loaded with dual color-developing substances with a polymer resin in a certain proportion, and then coats the surface of steel or magnesium alloy materials, thereby constructing a graded response self-warning anti-corrosion coating. The invention can respectively respond to coating surface damage and metal interface corrosion, and can give early warning to different damage degrees of the coating/metal system.

(2) The preparation method of the present invention is simple, and the double color-developing substance is loaded in the composite microcapsule, which has a wide application range, is easy to be applied on a large scale, and has broad market prospects.

Description of drawings

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 is a schematic diagram of the hierarchical response self-warning mechanism of the present invention;

Fig. 2 is a scanning electron microscope image of a composite microcapsule loaded with dual chromogenic substances in Example 1 of the present invention;

Detailed ways

In view of the problems existing in the current self-warning anti-corrosion coating, the inventor of the present application has been able to propose the technical solution of the present invention after long-term research and extensive practice.

The invention provides a graded response self-warning anti-corrosion coating, which is composed of composite microcapsules loaded with dual color-developing substances and polymer resin, and is mainly used for corrosion protection of steel and magnesium alloy materials.

The mass fraction of the composite microcapsule in the polymer resin is 1.5% to 15%, and the diameter of the composite microcapsule is 2 μm to 15 μm. The composite microcapsules are composed of polymer capsules and mesoporous silica loaded with a corrosion response agent, and the mass ratio of mesoporous silica to polymer capsules is 1:2˜1:10. The polymer capsule includes a shell layer and crystal violet lactone covered by the shell layer, the mass fraction of the crystal violet lactone in the polymer capsule is 10% to 30%, and the mesoporous silica contains The loading rate of the corrosion response agent is 5%-25%.

The material of the shell layer is one or any two of polymethyl methacrylate, polycaprolactone, polystyrene, chitosan and ethyl cellulose.

The corrosion response agent is phenolphthalein, fluorescein, thymol blue, p-nitrophenyl azoresorcinol, 2,4-dihydroxy-4'-nitroazobenzene, o-phenanthroline and hydroxyquinone One of the phyllolines.

The polymer resin is one of acrylic resin, polyurethane resin, epoxy resin and polyurea resin.

The present invention also provides a method for preparing a graded response self-warning anticorrosion coating, comprising the following steps:

S1. Dissolve the material of the shell layer and crystal violet lactone in dichloromethane at a mass ratio of 2:1 to 10:1, stir evenly and add dodecane with a concentration of 1 mg/mL to 3 mg/mL The sodium phenylbenzenesulfonate solution was stirred at a temperature of 30°C to 40°C for 10h to 30h, and centrifuged at a speed of 6000r/min to 8000r/min for 6min to 10min to obtain polymer capsules coated with crystal violet lactone;

S2. Dissolve the corrosion response agent and mesoporous silica in the ethanol solution at a mass ratio of 1:1 to 5:1, keep the pressure in an oven with a vacuum degree of -0.1MPa for 1h to 3h, and then place it at room temperature and Press down and stir mechanically for 5h-10h, and centrifuge to obtain mesoporous silica loaded with corrosion response agent;

S3. Disperse the polymer capsules coated with crystal violet lactone and the mesoporous silica loaded with corrosion response agent in a mass ratio of 1:2 to 1:10 in the sodium dodecylbenzenesulfonate solution, and stir , centrifugation to obtain composite microcapsules loaded with dual chromogenic substances;

S4. Add the composite microcapsules to the polymer resin and mix evenly, coat the surface of the steel or magnesium alloy material, and cure in an oven at 50°C to 80°C for 15h to 30h to obtain a graded response self-warning anti-corrosion coating.

Using the above preparation method, the present invention firstly prepares composite microcapsules loaded with dual color-developing substances, then adds the composite microcapsules to the polymer resin, mixes them and coats them on the surface of steel or magnesium alloy materials, thereby constructing a composite microcapsule on the metal surface Self-warning anti-corrosion coatings in response to coating surface damage and graded response to metal interface corrosion.

As shown in Figure 1, in the damaged area of the coating surface, the composite microcapsules rupture to release crystal violet lactone and have a color reaction with mesoporous silica, indicating the surface damage of the coating; when the surface damage triggers metal interface corrosion, the mesoporous The corrosion response agent in silica will produce obvious color changes to warn the occurrence of corrosion, and realize the self-warning of the graded response of coating damage.

The following will be described in conjunction with specific embodiments.

Example 1

S1. Dissolve 2 g of polymethyl methacrylate and 0.5 g of crystal violet lactone in 50 mL of dichloromethane, and stir evenly.

S2. Add the above solution into 150 mL of sodium dodecylbenzenesulfonate solution with a concentration of 1 mg/mL, stir evenly and transfer it to a round bottom flask, place it in an oil bath at 30°C and stir for 15 hours, then heat it at 6000r /min speed centrifugation for 6min to obtain polymer capsules coated with crystal violet lactone.

S3. Disperse 0.1g of phenolphthalein and 0.05g of mesoporous silica in 100mL of ethanol, keep the pressure in an oven with a vacuum degree of -0.1MPa for 1.5h, continue mechanically stirring for 5h under normal temperature and pressure, and obtain by centrifugation Mesoporous silica loaded with corrosion responsive agents.

S4. Disperse 0.1g of mesoporous silica loaded with a corrosion response agent and 0.2g of crystal violet lactone-coated polymer capsules in a sodium dodecylbenzenesulfonate solution, stir and centrifuge to obtain dual color development of the load Composite microcapsules of substances.

S5. Add the composite microcapsules to the acrylic resin and mix evenly to obtain a resin mixture. The mass fraction of the composite microcapsules in the acrylic resin is 1.5%.

S6. Coating the above resin mixture on the surface of carbon steel and curing it in an oven at 50° C. for 15 hours to obtain a graded response self-warning anti-corrosion coating.

Fig. 2 is a scanning electron microscope image of the composite microcapsules loaded with dual chromogenic substances in Example 1. It can be seen from Fig. 2 that the composite microcapsules are spherical in shape with a diameter of 2 μm to 15 μm.

Example 2

S1. Dissolve 5 g of polycaprolactone and 1.5 g of crystal violet lactone in 150 mL of dichloromethane, and stir evenly.

S2. Add the above solution into 300 mL of sodium dodecylbenzenesulfonate solution with a concentration of 2 mg/mL, stir evenly, transfer it to a round bottom flask, place it in an oil bath at 35°C and stir for 20 h, then heat it at 7000 r /min speed centrifugation for 6min to obtain polymer capsules coated with crystal violet lactone.

S3. Disperse 0.3g of fluorescein and 0.1g of mesoporous silica in 150mL of ethanol, keep the pressure in an oven with a vacuum degree of -0.1MPa for 2h, continue to mechanically stir for 5h under normal temperature and pressure, and obtain by centrifugation Mesoporous silica loaded with corrosion responsive agents.

S4. Disperse 0.1 g of mesoporous silica loaded with a corrosion response agent and 0.5 g of crystal violet lactone-coated polymer capsules in a sodium dodecylbenzenesulfonate solution, stir and centrifuge to obtain dual color development of the load Composite microcapsules of substances.

S5, adding the composite microcapsules into the polyurethane resin and mixing uniformly to obtain a resin mixture. The mass fraction of the composite microcapsules in the polyurethane resin is 5%.

S6. Coating the above resin mixture on the surface of the magnesium alloy and curing it in an oven at 60° C. for 20 hours to obtain a graded response self-warning anti-corrosion coating.

The surface of the graded response self-warning anti-corrosion coating prepared in Example 2 was scratched and then soaked in salt water for 1 hour to observe, and it was found that a clear blue color appeared at the scratch, which was mainly due to the release of crystal violet by the rupture of the composite microcapsules at the scratch. The ester reacts with mesoporous silica for color development.

Continue to observe the graded response prepared in Example 2 after soaking in salt water for 8 hours after scratching the surface of the self-warning anticorrosion coating, and find that the scratches appear obvious red, because as time goes by, the penetration of the corrosive medium causes the base metal Corrosion, hydroxide ions are generated in the localized corrosion area, and the corrosion response agent fluorescein in mesoporous silica turns red in an alkaline environment, warning the occurrence of metal substrate corrosion.

Example 3

S1. Dissolve 6 g of polystyrene and 2 g of crystal violet lactone in 200 mL of dichloromethane, and stir evenly.

S2. Add the above solution into 400mL of sodium dodecylbenzenesulfonate solution with a concentration of 2mg/mL, stir evenly and transfer it to a round bottom flask, place it in an oil bath at 35°C and stir for 25h, then heat at 8000r /min speed centrifugation for 6min to obtain polymer capsules coated with crystal violet lactone.

S3. Disperse 0.3g of p-nitrophenylazoresorcinol and 0.1g of mesoporous silica in 150mL of ethanol, and keep the pressure in an oven with a vacuum degree of -0.1MPa for 2h, and then in a normal temperature and pressure environment The mechanical stirring was continued for 8 hours, and the mesoporous silica loaded with the corrosion response agent was obtained by centrifugation.

S4. Disperse 0.1 g of mesoporous silica loaded with a corrosion response agent and 0.6 g of crystal violet lactone-coated polymer capsules in a sodium dodecylbenzenesulfonate solution, stir and centrifuge to obtain dual color development of the load Composite microcapsules of substances.

S5, adding the composite microcapsules into the epoxy resin and mixing uniformly to obtain a resin mixture. The mass fraction of the composite microcapsules in the epoxy resin is 8%.

S6. Coating the above resin mixture on the surface of the magnesium alloy and curing it in an oven at 60° C. for 20 hours to obtain a graded response self-warning anti-corrosion coating.

The preparation process of the graded response self-warning anti-corrosion coating provided by the invention is simple, and has dual warning functions for coating surface damage and metal interface corrosion, which effectively solves the problem that the existing technology cannot effectively warn the damage status and damage degree of the coating problem and has broad application prospects.

Of course, the above descriptions are not intended to limit the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or replacements made by those skilled in the art within the scope of the present invention shall also belong to the present invention. protection scope of the invention.

Claims (8)

1. The graded-response self-warning anticorrosive coating is characterized by comprising a composite microcapsule and polymer resin, wherein the composite microcapsule is loaded with double chromogenic substances, the composite microcapsule is composed of a polymer capsule and mesoporous silica loaded with a corrosion response agent, and the polymer capsule comprises a shell layer and crystal violet lactone coated by the shell layer.

2. The graded-response self-warning anticorrosive coating according to claim 1, wherein the composite microcapsule is 1.5-15% by mass of the polymer resin.

3. The graded-response self-warning anticorrosive coating according to claim 1 or 2, wherein the mass ratio of the mesoporous silica to the polymer capsule in the composite microcapsule is 1:2-1.

4. The graded-response self-warning anticorrosive coating according to claim 3, wherein the diameter of the composite microcapsule is 2-15 μm, the mass fraction of crystal violet lactone in the polymer capsule is 10-30%, and the loading rate of the corrosion response agent in the mesoporous silica is 5-25%.

5. The graded-response self-warning anticorrosive coating according to claim 4, wherein the shell layer is made of one or two of polymethyl methacrylate, polycaprolactone, polystyrene, chitosan and ethyl cellulose.

6. The graded-response self-warning anticorrosive coating according to claim 5, wherein the corrosion-responsive agent is one of phenolphthalein, fluorescein, thymol blue, paranitroazoresorcinol, 2,4-dihydroxy-4' -nitroazobenzene, phenanthroline, and hydroxyquinoline.

7. The graded-response self-warning anticorrosive coating according to claim 6, wherein the polymer resin is one of an acrylic resin, a polyurethane resin, an epoxy resin, and a polyurea resin.

8. A method of preparing a graded-response self-warning corrosion protective coating according to any one of claims 1 to 7, comprising the steps of:

s1, dissolving the material of the shell layer and crystal violet lactone in dichloromethane together according to a mass ratio of 2:1-10;

s2, dissolving the corrosion response agent and the mesoporous silica into an ethanol solution together according to the mass ratio of 1:1-5:1, maintaining the pressure in an oven with the vacuum degree of-0.1 MPa for 1-3 h, mechanically stirring at normal temperature and normal pressure for 5-10 h, and centrifuging to obtain the mesoporous silica loaded with the corrosion response agent;

s3, dispersing the polymer capsule coated with crystal violet lactone and the mesoporous silica loaded with the corrosion response agent into a sodium dodecyl benzene sulfonate solution according to a mass ratio of 1:2-1;

and S4, adding the composite microcapsule into polymer resin, uniformly mixing, coating the mixture on the surface of a steel or magnesium alloy material, and curing the mixture in an oven at the temperature of 50-80 ℃ for 15-30 h to obtain the graded response self-warning anticorrosive coating.

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