CN115895317B - Graded response self-early warning anti-corrosion coating and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of metal anti-corrosion, and specifically discloses a graded response self-warning anti-corrosion coating. It consists of composite microcapsules loaded with dual color-developing substances and polymer resin. The composite microcapsules are composed of polymer capsules and mesoporous silica loaded with corrosion response agents. The polymer capsules include a shell layer and a shell layer. Coated crystal violet lactone. The mass fraction of the composite microcapsules in the polymer resin is 1.5% to 15%. The mass ratio of mesoporous silica to polymer capsules in the composite microcapsules is 1:2 to 1:10. The mass fraction of crystal violet lactone in the polymer capsule is 10% to 30%, and the loading rate of the corrosion response agent in the mesoporous silica is 5% to 25%. The invention also discloses a method for preparing a graded response self-warning anti-corrosion coating. The invention can respond to coating surface damage and metal interface corrosion respectively, and can provide early warning for different degrees of damage to the coating/metal system.

Description

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

Technical field

The invention belongs to the technical field of metal anti-corrosion, and specifically relates to a graded response self-warning anti-corrosion 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 coating. In addition, local defects will lead to the intrusion of corrosive media and trigger a 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, timely discovery of damaged locations of coating materials and interface corrosion sites, and effective assessment of the service status of the coating are of great significance to ensuring the service safety and lifespan 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 local regional material composition and acid-base fluctuations during the metal corrosion process, corrosion-responsive substances are introduced into the resin to obtain a self-warning composite coating. At the location where the coating is damaged, the corrosion-responsive substances undergo a color reaction under the action of the local corrosion microenvironment to provide an early warning of the occurrence of corrosion. However, coating damage and failure is a gradual development process, involving multiple processes such as surface damage, interface corrosion, and coating peeling. A single early warning mechanism cannot effectively warn the damage status and extent of the coating.

Therefore, there is an urgent need to develop self-warning intelligent coatings that respond dually to coating surface damage or metal interface corrosion to achieve real-time warning during the coating service process.

Contents of the invention

One object of the present invention is to provide a graded response self-warning anti-corrosion coating, which effectively solves the problem that the existing technology cannot effectively provide early warning of the damage status and degree of damage to the coating.

In order to solve the above technical problems, the technical solution adopted by the present invention is:

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

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

Further, the mass ratio of mesoporous silica to polymer capsules in the composite microcapsules is 1:2 to 1:10.

Further, the diameter of the composite microcapsules is 2 μm to 15 μm, the mass fraction of crystal violet lactone in the polymer capsule is 10% to 30%, and the load 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 hydroxyquinoline.

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 effectively solves the problem that the existing technology cannot effectively warn the damage status and degree of damage of the coating.

A method for preparing a graded response self-warning anti-corrosion coating as described in the above embodiment, including the following steps:

S1. Dissolve the shell material and crystal violet lactone in methylene chloride at a mass ratio of 2:1 to 10:1, stir evenly and then add dodecane with a concentration of 1 mg/mL to 3 mg/mL. Stir the sodium benzene sulfonate solution at a temperature of 30°C to 40°C for 10h to 30h, and centrifuge at a speed of 6000r/min to 8000r/min for 6min to 10min to obtain a polymer capsule 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 of -0.1MPa for 1h to 3h, and then store it at room temperature. Stir mechanically under pressure for 5h to 10h, and obtain mesoporous silica loaded with corrosion response agent through centrifugation;

S3. Disperse the crystal violet lactone-coated polymer capsule and the mesoporous silica loaded with the corrosion response agent in a sodium dodecyl benzene sulfonate solution at a mass ratio of 1:2 to 1:10, and stir , centrifuge to obtain composite microcapsules loaded with dual color-developing substances;

S4. Add the composite microcapsules to the polymer resin and mix evenly, coat it on the surface of steel or magnesium alloy materials, and cure it 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 effects of the present invention are:

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

(2) The preparation method of the present invention is simple. Dual color-developing substances are loaded into composite microcapsules. It has a wide range of applications, is easy to be applied on a large scale, and has broad market prospects.

Description of the drawings

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

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

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

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

The corrosion response agents are phenolphthalein, fluorescein, thymol blue, p-nitrophenylazoresorcinol, 2,4-dihydroxy-4'-nitroazobenzene, o-phenanthroline and hydroxyquin A kind of phyrin.

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

The invention also provides a method for preparing a graded response self-warning anti-corrosion coating, which includes the following steps:

S1. Dissolve the shell material and crystal violet lactone in methylene chloride at a mass ratio of 2:1 to 10:1, stir evenly and then add dodecane with a concentration of 1 mg/mL to 3 mg/mL. Stir the sodium benzene sulfonate solution at a temperature of 30°C to 40°C for 10h to 30h, and centrifuge at a speed of 6000r/min to 8000r/min for 6min to 10min to obtain a polymer capsule 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 of -0.1MPa for 1h to 3h, and then store it at room temperature. Stir mechanically under pressure for 5h to 10h, and obtain mesoporous silica loaded with corrosion response agent through centrifugation;

S3. Disperse the crystal violet lactone-coated polymer capsule and the mesoporous silica loaded with the corrosion response agent in a sodium dodecylbenzene sulfonate solution at a mass ratio of 1:2 to 1:10, and stir , centrifuge to obtain composite microcapsules loaded with dual color-developing substances;

S4. Add the composite microcapsules to the polymer resin and mix evenly, coat it on the surface of steel or magnesium alloy materials, and cure it 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 first prepares composite microcapsules loaded with dual color-developing substances, then adds the composite microcapsules to the polymer resin, mixes them evenly, and then coats them on the surface of steel or magnesium alloy materials, thereby constructing a structure on the metal surface. Self-warning anti-corrosion coating with graded response to coating surface damage and 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 react with mesoporous silica to develop a color, indicating coating surface damage; when surface damage triggers metal interface corrosion, the mesoporous The corrosion response agent in silica will produce obvious color changes to provide early warning of the occurrence of corrosion, and achieve self-warning of coating damage with graded response.

Description will be made below with reference to specific embodiments.

Example 1

S1. Dissolve 2g polymethylmethacrylate and 0.5g crystal violet lactone in 50mL methylene chloride and stir evenly.

S2. Add the above solution to 150 mL of sodium dodecyl benzene sulfonate solution with a concentration of 1 mg/mL, stir evenly and transfer to a round-bottomed flask. Place it in a 30°C oil bath and stir for 15 hours. Then, stir at 6000r /min speed for 6 minutes to obtain polymer capsules coated with crystal violet lactone.

S3. Disperse 0.1g phenolphthalein and 0.05g mesoporous silica in 100mL ethanol. After maintaining the pressure in an oven with a vacuum of -0.1MPa for 1.5h, continue mechanical 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 corrosion response agent and 0.2g of polymer capsule coated with crystal violet lactone in sodium dodecyl benzene sulfonate solution, stir and centrifuge to obtain loaded dual color development 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. Coat the above resin mixture on the surface of carbon steel and cure it in a 50°C oven for 15 hours to obtain a graded response self-warning anti-corrosion coating.

Figure 2 is a scanning electron microscope image of the composite microcapsules loaded with dual color-developing substances in Example 1. It can be seen from Figure 2 that the composite microcapsules are spherical and have a diameter of 2 μm to 15 μm.

Example 2

S1. Dissolve 5g polycaprolactone and 1.5g crystal violet lactone in 150mL methylene chloride and stir evenly.

S2. Add the above solution to 300 mL of sodium dodecyl benzene sulfonate solution with a concentration of 2 mg/mL, stir evenly and then transfer it to a round-bottomed flask. Place it in a 35°C oil bath and stir for 20 hours. Then, stir at 7000r /min speed for 6 minutes to obtain polymer capsules coated with crystal violet lactone.

S3. Disperse 0.3g fluorescein and 0.1g mesoporous silica in 150mL ethanol. After maintaining the pressure in an oven with a vacuum of -0.1MPa for 2 hours, continue mechanical stirring for 5 hours at normal temperature and pressure, and obtain by centrifugation. Mesoporous silica loaded with corrosion responsive agents.

S4. Disperse 0.1g of mesoporous silica loaded with corrosion responder and 0.5g of polymer capsule coated with crystal violet lactone in sodium dodecylbenzene sulfonate solution, stir and centrifuge to obtain loaded dual color development Composite microcapsules of substances.

S5. Add the composite microcapsules to the polyurethane resin and mix evenly to obtain a resin mixture. The mass fraction of the composite microcapsules in the polyurethane resin is 5%.

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

After the surface of the graded response self-warning anti-corrosion coating prepared in Example 2 was scratched and soaked in salt water for 1 hour, it was observed that an obvious blue color appeared at the scratch, mainly due to the rupture of the composite microcapsules at the scratch and the release of crystal violet content. The ester reacts with mesoporous silica to develop color.

Continuing to observe the surface of the graded response self-warning anti-corrosion coating prepared in Example 2 after being scratched and immersed in salt water for 8 hours, it was found that an obvious red color appeared at the scratch, because as time went by, the penetration of the corrosive medium caused the base metal to Corrosion produces hydroxide ions in the local corrosion area, and the corrosion response agent fluorescein in the mesoporous silica turns red in an alkaline environment, giving an early warning of the occurrence of metal substrate corrosion.

Example 3

S1. Dissolve 6g polystyrene and 2g crystal violet lactone in 200mL methylene chloride and stir evenly.

S2. Add the above solution to 400 mL of sodium dodecyl benzene sulfonate solution with a concentration of 2 mg/mL, stir evenly and transfer to a round-bottomed flask. Place it in a 35°C oil bath and stir for 25 hours. Then, stir at 8000r /min speed for 6 minutes to obtain polymer capsules coated with crystal violet lactone.

S3. Disperse 0.3g p-nitrophenylazoresorcin and 0.1g mesoporous silica in 150mL ethanol. After maintaining the pressure for 2 hours in an oven with a vacuum degree of -0.1MPa, place it under normal temperature and pressure. Mechanical stirring was continued for 8 h, and mesoporous silica loaded with corrosion responder was obtained by centrifugation.

S4. Disperse 0.1g of mesoporous silica loaded with corrosion response agent and 0.6g of polymer capsule coated with crystal violet lactone in sodium dodecyl benzene sulfonate solution, stir and centrifuge to obtain loaded dual color development Composite microcapsules of substances.

S5. Add the composite microcapsules to the epoxy resin and mix evenly to obtain a resin mixture. The mass fraction of the composite microcapsules in the epoxy resin is 8%.

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

The graded response self-warning anti-corrosion coating provided by the present invention has a simple preparation process, has a dual warning function for coating surface damage and metal interface corrosion, and effectively solves the problem that the existing technology cannot effectively provide early warning for the damage status and degree of damage of the coating. problems and has broad application prospects.

Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by those skilled in the art within the essential scope of the present invention should also fall within the scope of the present invention. protection scope of the invention.

Claims (6)

1. A method for preparing a graded response self-warning anti-corrosion coating, characterized in that the graded response self-warning anti-corrosion coating is composed of composite microcapsules loaded with dual color-developing substances and a polymer resin, and the composite microcapsules are composed of It consists of a polymer capsule and mesoporous silica loaded with a corrosion response agent. The polymer capsule includes a shell layer and crystal violet lactone coated by the shell layer, and is used for corrosion protection of steel and magnesium alloy materials; The preparation method includes the following steps: S1. Dissolve the shell material and crystal violet lactone in methylene chloride at a mass ratio of 2:1 to 10:1, stir evenly and then add dodecane with a concentration of 1 mg/mL to 3 mg/mL. Stir the sodium benzene sulfonate solution at a temperature of 30°C to 40°C for 10h to 30h, and centrifuge at a speed of 6000r/min to 8000r/min for 6min to 10min to obtain a polymer capsule 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 of -0.1MPa for 1h to 3h, and then store it at room temperature. Stir mechanically under pressure for 5h to 10h, and obtain mesoporous silica loaded with corrosion response agent through centrifugation; S3. Disperse the crystal violet lactone-coated polymer capsule and the mesoporous silica loaded with the corrosion response agent in a sodium dodecylbenzene sulfonate solution at a mass ratio of 1:2 to 1:10, and stir , centrifuge to obtain composite microcapsules loaded with dual color-developing substances; S4. Add the composite microcapsules to the polymer resin and mix evenly, coat it on the surface of steel or magnesium alloy materials, and cure it in an oven at 50°C to 80°C for 15h to 30h to obtain a graded response self-warning anti-corrosion coating; In the damaged area of the coating surface, the composite microcapsules rupture to release crystal violet lactone and react with the mesoporous silica to develop a color, indicating the coating surface damage; when the surface damage triggers metal interface corrosion, the corrosion response in the mesoporous silica The agent will produce obvious color changes, early warning of the occurrence of corrosion, and achieve self-warning of graded response to coating damage. 2. The method for preparing a graded response self-warning anti-corrosion coating according to claim 1, characterized in that the mass fraction of the composite microcapsules in the polymer resin is 1.5% to 15%. 3. The preparation method of the graded response self-warning anti-corrosion coating according to claim 2, characterized in that the diameter of the composite microcapsule is 2 μm to 15 μm, and the mass fraction of crystal violet lactone in the polymer capsule The loading rate of the corrosion response agent in the mesoporous silica is 5% to 25%. 4. The preparation method of the graded response self-warning anti-corrosion coating according to claim 3, characterized in that the material of the shell layer is polymethyl methacrylate, polycaprolactone, polystyrene, or chitosan. and ethyl cellulose, or any two of them. 5. The preparation method of graded response self-warning anti-corrosion coating according to claim 4, characterized in that the corrosion response agent is phenolphthalein, fluorescein, thymol blue, p-nitrophenylazoresorcinol , one of 2,4-dihydroxy-4'-nitroazobenzene, o-phenanthroline and hydroxyquinoline. 6. The method for preparing a graded response self-warning anti-corrosion coating according to claim 5, characterized in that the polymer resin is one of acrylic resin, polyurethane resin, epoxy resin and polyurea resin.