CN113249025B

CN113249025B - Near-infrared quick response accurate self-repairing anticorrosive coating and preparation method thereof

Info

Publication number: CN113249025B
Application number: CN202110666262.1A
Authority: CN
Inventors: 王海波; 许峻槐; 成煦; 杜宗良; 杜晓声
Original assignee: Sichuan University
Current assignee: Sichuan University
Priority date: 2021-06-16
Filing date: 2021-06-16
Publication date: 2022-03-25
Anticipated expiration: 2041-06-16
Also published as: CN113249025A

Abstract

The invention provides a near-infrared quick-response accurate self-repairing anticorrosive coating and a preparation method thereof, wherein the coating comprises furan-modified nano particles and a maleimide-terminated polyurethane coating substrate, the furan-modified nano particles are dopamine-coated CeO2 nano particles, and furan groups are grafted on the surfaces of the dopamine-coated CeO2 nano particles. And (2) placing the uniformly dispersed dopamine-coated nanoparticle ethanol dispersion liquid at 60 ℃, adjusting the pH to about 9 by using triethylamine, dropwise adding furfuryl mercaptan, continuously stirring for reacting for 24 hours, centrifugally separating out nanoparticles, uniformly dispersing by using butanone, finally adding the nanoparticles into maleimide-terminated polyurethane, then uniformly stirring and mixing, and drying to obtain the near-infrared quick-response accurate self-repairing anticorrosive coating.

Description

Near-infrared quick response accurate self-repairing anticorrosive coating and preparation method thereof

Technical Field

The invention relates to the technical field of self-repairing anticorrosive coatings, in particular to a near-infrared quick-response accurate self-repairing anticorrosive coating and a preparation method thereof.

Background

Due to the excellent physical and chemical properties of the metal material, the metal material is widely applied to the aspects of military industry, deep sea, capital construction, daily life of people and the like. However, metals are inevitably subject to wear and corrosion due to various adverse factors such as external force, corrosive media, etc. during use. At the same time, the corrosion behavior of metals is also a process of decreasing Gibbs free energy, resulting in metals that are more prone to corrosion. According to statistics, 20% of metal materials in the world cannot be recycled due to corrosion, which causes huge waste of metal resources, so that the corrosion prevention of metals is generally regarded as important. However, in practical application, the common anticorrosive coating cannot avoid the generation of fine cracks after the deformation or impact of the base material, so that the protective effect of the coating is lost, and the base material cannot be effectively protected.

The self-repairing anticorrosive coating material has a self-repairing function after the coating is damaged or microcracks are generated. The self-repairing of the coating which can be damaged repeatedly in the external environment is the aim of the future anticorrosion coating field. Currently, the self-healing function studied in the industry is mostly based on the addition of microcapsules in the coating, which encapsulate the healing agent, and which release automatically when the coating breaks (CN 102719184 a, CN 104624132A, CN 106215826A, CN 102604469 a, CN 102702838A). However, the self-repairing material of the external aid type loses the repairing effect after repairing for a certain number of times, namely after the repairing agent in the capsule is released. Therefore, there is a need for a coating material that can realize repeated self-repair without the limitation of the number of times.

Contents of the invention

The invention aims to overcome the defects of the prior art, organically combines the furan-modified CeO2 nanoparticles with maleimide-terminated polyurethane, and provides a precise self-repairing anticorrosive coating material with near-infrared quick response.

The purpose of the invention is realized by the following technical scheme: the near-infrared quick-response accurate self-repairing anticorrosive coating comprises furan-modified nanoparticles and a maleimide-terminated coating substrate, wherein the nanoparticles are dopamine-coated CeO2 nanoparticles, and furan groups are grafted on the surfaces of the dopamine-coated CeO2 nanoparticles. The CeO2 nano particles with excellent corrosion resistance are used as corrosion inhibitors, and the dopamine is wrapped on the surfaces of the CeO2 nano particles to introduce the photothermal conversion capability of the dopamine, so that the high-efficiency conversion of near infrared light is realized; meanwhile, the furan group modified on the surface of dopamine can react with maleimide-terminated polyurethane through DA to realize self-repair of the coating. When the coating is cracked or impacted, CeO2 nano particles in the coating can react with corrosive ions and water to generate insoluble metal compounds, and further diffusion of the corrosive ions is effectively isolated; meanwhile, the near infrared light irradiates the coating at a fixed point efficiently and accurately, so that the self-repairing function of the coating is realized.

The furan group is introduced by reacting furfuryl thiol with dopamine on the surface layer of the nanoparticle. The furan group and the maleimide can generate reversible reaction, and the self-repairing of the coating is realized by utilizing the reaction.

The particle size of the furan-modified nano particles is 200-400 nm. The particle size of the CeO2 nano particles is 20-50 nm.

The mass of the nano particles is 1% -10% of that of the coating matrix. Further preferably, the mass of the nano particles is 2-5% of the mass of the coating matrix.

The coating substrate is polyurethane, and the polyurethane is synthesized by diisocyanate and diol compounds and is terminated by monohydroxy maleimide.

The diisocyanate is selected from one of isophorone diisocyanate, toluene diisocyanate, dicyclohexylmethane diisocyanate and diphenylmethane diisocyanate; the diol compound is selected from one of polyethylene glycol, polypropylene glycol and polytetrahydrofuran ether glycol.

A preparation method of a near-infrared quick-response accurate self-repairing anticorrosive coating comprises the following steps:

s1, dispersing CeO2 nanoparticles in a Tris-HCl buffer solution, adding dopamine hydrochloride, stirring at a high speed for 12 hours, separating an aqueous solution from dopamine-modified nanoparticles by centrifugation, and then dispersing the nanoparticles in ethanol to be uniformly dispersed;

s2, adjusting the pH of the uniformly dispersed dopamine-coated nanoparticle ethanol dispersion liquid to 8.5-9.5 by using triethylamine, preferably adjusting the pH to 9, dropwise adding furfuryl mercaptan, continuously stirring and reacting for 24 hours at the temperature of 60 ℃, centrifugally separating out furan group-modified nanoparticles, and uniformly dispersing by using butanone;

s3, carrying out catalytic reaction on diisocyanate and a diol compound, carrying out chain extension by using butanediol, and finally adding monohydroxy maleimide for end capping to prepare maleimide-terminated polyurethane; the diisocyanate is selected from one of isophorone diisocyanate, toluene diisocyanate, dicyclohexylmethane diisocyanate and diphenylmethane diisocyanate; the diol compound is selected from one of polyethylene glycol, polypropylene glycol and polytetrahydrofuran ether glycol. Further, the molecular weight of the diol compound is preferably 2000.

And S4, adding the dispersed nano particles prepared in the S2 into the maleimide-terminated polyurethane prepared in the S3 according to a certain proportion, then uniformly stirring and mixing, and drying to obtain the accurate self-repairing anticorrosive coating with the near-infrared quick response.

The invention has the beneficial effects that:

1. the invention successfully constructs the accurate self-repairing anticorrosive coating with near-infrared quick response. The contact of corrosive ions and water with a metal material is blocked by the anticorrosion effect of CeO2, near infrared light is efficiently converted into heat energy by the photothermal effect of dopamine, and the formation of DA bonds is accelerated under the influence of temperature, so that the self-repairing of the polyurethane anticorrosion coating is realized.

2. The modified nano particles can be uniformly dispersed in the coating matrix, so that the mechanical property of the coating material is ensured.

3. The invention realizes the accurate self-repairing of the coating by the irradiation of near infrared light, overcomes the self-repairing times of the existing self-repairing coating, has simple construction and low cost, can be effectively combined with various coating substrate materials, and has good application prospect and wide development space.

Drawings

FIG. 1 is a graph of mechanical properties of coating materials of different nanoparticle contents;

FIG. 2 is a graph of the impedance values of coating materials of different nanoparticle content after one day of immersion;

FIG. 3 is a polarizing microscope photograph and a scanning electron microscope photograph of the coating material with a nano particle content of 5% before and after self-repairing;

FIG. 4 shows the impedance values before and after self-repairing of a coating with a nanoparticle content of 5%;

FIG. 5 is a graph of the coating resistance at 0.01Hz of the coating material with 5% nanoparticles as a function of time.

Detailed Description

The technical solutions of the present invention are further described in detail below with reference to the accompanying drawings, but the scope of the present invention is not limited to the following.

Example 1

1. preparation method of furan modified nano particles

Weighing 10g of CeO2 nanoparticles with the particle size of 50nm, dispersing the 10g of CeO2 nanoparticles in 500mL of Tris-HCl buffer solution with the molar mass concentration of 10mM and the pH value of 8.5, adding 5g of dopamine hydrochloride, stirring at a high speed for 12 hours, centrifuging to separate the nanoparticles, and dispersing the nanoparticles uniformly by using ethanol.

Placing 15g of the uniformly dispersed dopamine-coated nanoparticle ethanol dispersion at 60 ℃, adjusting the pH to 9 with triethylamine, dropwise adding 20g of furfuryl mercaptan, continuously stirring for reacting for 24 hours, centrifugally separating out nanoparticles, and uniformly dispersing with butanone.

2. Method for synthesizing maleimide-terminated polyurethane

20.25g of isophorone diisocyanate and 24.75g of polypropylene glycol were reacted at 85 ℃ under the presence of a catalyst for two hours, followed by chain extension with 4.54g of butanediol and finally end-capping with 8g of monohydroxy maleimide to give a maleimide-terminated polyurethane.

3. Preparation method of near-infrared quick-response accurate self-repairing anticorrosive coating

1g of furan modified nano particles dispersed by butanone and 100g of maleimide terminated polyurethane are mixed, stirred for 2 hours at 1000rpm/min and dried to obtain the self-repairing anticorrosive coating with the nano particle content of 1%.

Example 2

1. preparation of furan modified nanoparticles

2. Method for synthesizing maleimide-terminated polyurethane

2g of furan modified nano particles dispersed by butanone and 100g of maleimide terminated polyurethane are mixed, stirred for 2 hours at 1000rpm/min and dried to obtain the self-repairing anticorrosive coating with the nano particle content of 2 percent.

Example 3

1. preparation of furan modified nanoparticles

2. Method for synthesizing maleimide-terminated polyurethane

5g of nano particle dispersion and 100g of maleimide-terminated polyurethane are mixed, stirred for 2 hours at 1000rpm/min, and dried to obtain the self-repairing anticorrosive coating with the nano particle content of 5%.

Example 4

1. preparation of furan modified nanoparticles

2. Method for synthesizing maleimide-terminated polyurethane

And (3) mixing 10g of nano particle dispersion with 100g of maleimide-terminated polyurethane, stirring for 2 hours at 1000rpm/min, and drying to obtain the self-repairing anticorrosive coating with the nano particle content of 10%.

Property testing of examples

The near-infrared self-repairing anticorrosive coating material prepared by the embodiment of the invention is subjected to the following property detection:

1. mechanical property curve of coating with different nano particle content

(1) FIG. 1 is a graph of tensile properties of coatings of varying nanoparticle content, and it can be seen from FIG. 1 that the elongation of the coating decreases with increasing nanoparticle content, while the tensile strength shows a tendency to increase first and then decrease, and both are greater than 25MPa, with the tensile properties being the best at 5% (about 40 MPa). The coating without the added nano particles only has the tensile strength of less than 10MPa, which shows that the nano particles have obvious improvement effect on the mechanical property of the coating.

2. Testing of corrosion resistance of coatings

(1) The electrochemical alternating current impedance spectrum is a commonly used means for evaluating the corrosion resistance of the coating, and in the test process, a measurement system can not be greatly changed, so that parameters related to coating corrosion, such as coating capacitance, coating resistance, double electric layer resistance and the like under different frequencies can be obtained. The larger the resistance value of the coating material is, the better the corrosion resistance of the material is. Fig. 2 and 4 show the results of tests by means of electrochemical impedance spectroscopy.

(2) The corrosion resistance of different nano particle contents is judged in 3.5 percent NaCl solution by an electrochemical alternating current impedance spectroscopy method. Fig. 2 is a resistance value of the coating layer after being soaked in 3.5% NaCl solution for 1 day, from which it can be seen that the corrosion prevention performance of the coating layer is sharply increased after the nanoparticles are added, but the resistance value of the coating layer shows a tendency of rising first and then falling as the content of the nanoparticles increases, wherein the corrosion prevention performance of the coating layer at the content of 5% is the best. This is because in a high content of coating, the nanoparticles are not uniformly dispersed and agglomerate, thereby causing the corrosion resistance of the coating to be reduced.

3. Self-repair performance test of coating

(1) The prepared coating also has high-efficiency photothermal conversion performance due to the dopamine. Firstly, the coating is scratched, then the coating is irradiated by near infrared light to generate self-repairing behavior, and finally the impedance value of the coating is detected.

(2) Fig. 3 shows that the scratch on the coating layer disappears after irradiation of near infrared light, as seen by a polarization microscope and a scanning electron microscope.

(3) It is obvious from fig. 4 that the impedance value of the coating before and after self-repairing is almost unchanged, which shows that the material can well repair the anti-corrosion performance of the coating by near infrared light irradiation.

4. Ultra-long durability of the coating

(1) The resistance value of the coating in 3.5% NaCl solution changes along with time, and as can be seen from FIG. 5, the change of the corrosion resistance of the coating is mainly divided into three stages. In the first stage, as water molecules enter the coating, the coating expands to fill gaps in the coating, so that the corrosion resistance value of the coating is increased. In the second stage, the corrosion ions and water react with CeO2 to isolate the liquid from the substrate, so that the corrosion resistance of the coating remains stable. In the third stage, the corrosion resistance value of the coating is slowly reduced along with the continuous invasion of corrosion ions and water.

The results show that the invention successfully constructs the anticorrosive coating with near-infrared high-speed response accurate self-repair.

In the above example, the corrosion inhibitor may be CeO2, and may also be a series of inorganic nanoparticle corrosion inhibitors such as SiO2 that can react with water to form insoluble metal compounds. The coating base material can be polyurethane, acrylic resin or epoxy resin.

The foregoing is illustrative of the preferred embodiments of this invention, and it is to be understood that the invention is not limited to the precise form disclosed herein and that various other combinations, modifications, and environments may be resorted to, falling within the scope of the concept as disclosed herein, either as described above or as apparent to those skilled in the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A near-infrared quick response accurate self-repairing anticorrosive coating is characterized in thatCharacterized in that: including furan-modified CeO₂Nanoparticles and maleimide terminated polyurethane coated substrate, said CeO₂The nano particles are CeO coated by dopamine and can react with water to generate insoluble metal compounds₂The dopamine nanoparticle comprises nanoparticles, wherein furan groups are grafted on the surfaces of the nanoparticles coated with dopamine.

2. The near-infrared fast-response accurate self-repairing anticorrosive coating as claimed in claim 1, characterized in that: the furan group is introduced by reacting furfuryl thiol with dopamine on the surface layer of the nanoparticle.

3. The near-infrared fast-response accurate self-repairing anticorrosive coating as claimed in claim 2, characterized in that: the polyurethane coating substrate is synthesized from diisocyanate and a diol compound and is terminated by monohydroxy maleimide.

4. The near-infrared fast-response accurate self-repairing anticorrosive coating as claimed in claim 3, characterized in that: the diisocyanate is selected from one of isophorone diisocyanate, toluene diisocyanate, dicyclohexylmethane diisocyanate and diphenylmethane diisocyanate; the diol compound is selected from one of polyethylene glycol, polypropylene glycol and polytetrahydrofuran ether glycol.

5. The near-infrared fast-response accurate self-repairing anticorrosive coating as claimed in claim 3, characterized in that: the CeO modified with furan₂The mass of the nano particles is 1% -10% of that of the polyurethane coating matrix.

6. A method for preparing the near-infrared fast-response accurate self-repairing anticorrosive coating according to any one of claims 3 to 5, characterized in that: the method comprises the following steps:

s1, mixing CeO₂Dispersing the nano particles in Tris-HCl buffer solution, adding dopamine hydrochloride, stirring at high speed, and centrifugally separating to obtain nano particlesThe particles are uniformly dispersed by ethanol; adjusting the pH of the uniformly dispersed dopamine-coated nanoparticle ethanol dispersion liquid by using triethylamine, dropwise adding furfuryl mercaptan, continuously stirring for reaction, centrifugally separating nanoparticles, and uniformly dispersing the nanoparticles by using butanone;

s2, carrying out catalytic reaction on diisocyanate and a diol compound, carrying out chain extension by using butanediol, and finally adding monohydroxy maleimide for end capping to prepare maleimide-terminated polyurethane;

and S3, adding the dispersed nano particles prepared in the S1 into the maleimide-terminated polyurethane prepared in the S2, then stirring and mixing uniformly, and drying to obtain the accurate self-repairing anticorrosive coating with near-infrared quick response.

7. The preparation method of the near-infrared quick-response accurate self-repairing anticorrosive coating according to claim 6, characterized in that: in the S1, the substance of Tris-HCl buffer solution is in a concentration of 10mM and has a pH of 8.5.

8. The preparation method of the near-infrared quick-response accurate self-repairing anticorrosive coating according to claim 6, characterized in that: in said S1, the pH was adjusted to 8.5-9.5 with triethylamine.

9. The preparation method of the near-infrared quick-response accurate self-repairing anticorrosive coating according to claim 6, characterized in that: in the S2, isophorone diisocyanate and polypropylene glycol are reacted for two hours at 85 ℃ under the condition of a catalyst, and chain extension is carried out by using butanediol.