Efficient flame-retardant self-repairing coating and preparation method thereof

Abstract

The invention provides an efficient flame-retardant self-repairing coating and a preparation method thereof. Comprising the following steps: mixing and stirring 100 parts of a water-based copolymer, 10-15 parts of a terpolymer, 5-10 parts of low-melting-point glass powder and 3-8 parts of modified boron nitride nanosheets, adding 2-3 parts of a defoaming agent, and stirring to obtain the efficient flame-retardant self-repairing coating. According to the invention, by adding the terpolymer, strong adhesion to a substrate is formed, meanwhile, wide hydrogen bonds and other non-covalent interactions are formed among terpolymer chains, and rapid self-healing at normal temperature can be realized through a series of dynamic non-covalent interactions; due to the self-healing characteristic, the surface coating can spontaneously recover the protection function after being damaged, and the function of the surface coating can be played in an external environment which is easy to damage. Besides, a compact carbon layer with a complete structure can be rapidly formed when the flame retardant meets fire, combustible gas can be diluted, and chain reaction is inhibited by releasing phosphorus-containing free radicals to quench active free radicals in a gas phase, so that the flame retardance of the material is greatly improved.

Description

Technical Field The present invention relates to the field of coatings, and in particular to a highly efficient flame-retardant self-repairing coating and a preparation method thereof. Background Art Water-based paint is a paint that uses water instead of organic solvents as a dispersion. Compared with traditional oil-based paints, it has the advantages of low organic compound emissions, green environmental protection, safety and reliability, and water-based paint has excellent mechanical properties and can be adjusted, low temperature resistance, good compatibility and other advantages, which makes it have a wide range of application prospects in architectural coatings. With the development of the architectural coating market, coatings with specific functions are increasingly favored by people. At present, most water-based paints on the market do not have flame retardant properties, or have poor flame retardancy, which greatly reduces their practicality and scope of application in the construction industry. At present, the market mainly uses the method of adding flame retardants to improve the flame retardant properties of water-based paints. Generally, the amount of flame retardants used is relatively large, and there are also problems such as poor compatibility, which affects the mechanical properties, resistance and mechanical properties of water-based paints. In addition, water-based architectural paints will have problems such as scratches during long-term use, which will cause damage to the appearance and greatly reduce the protective ability of the coating. Therefore, the lack of self-repairing ability for microcracks is a shortcoming of most water-based architectural paints on the market. Therefore, research and development of highly efficient flame-retardant and self-healing coatings is of great significance to the development of the construction industry. Summary of the invention

[0003] Technical problems to be solved: In view of the above technical problems, the present invention proposes a highly efficient flame-retardant self-healing coating and its preparation method. The present invention adds a terpolymer, which is copolymerized by hydroxyethyl acrylate, vinylphosphonic acid and methacrylate dopamine. Through the interaction between the benzene ring and the catechol group, a strong adhesion to the substrate is formed. At the same time, extensive hydrogen bonds and other non-covalent interactions are formed between the terpolymer chains, which can be rapidly self-healed at room temperature through a series of dynamic non-covalent interactions. The self-healing property enables the surface coating to spontaneously restore its protective function after damage and play its role in an easily damaged external environment. In addition, it can quickly form a dense, structurally intact carbon layer when it encounters fire, and can dilute the combustible gas, and suppress the chain reaction by releasing phosphorus-containing free radicals to quench the active free radicals in the gas phase, which greatly improves the flame retardancy of the material.

[0004] Technical solution: A highly efficient flame-retardant self-repairing coating, comprising the following components in parts by weight: water-based copolymer, terpolymer, low-melting-point glass powder, and modified boron nitride nanosheets; The terpolymer is prepared by copolymerization of hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate. Furthermore, the water-based copolymer includes water-based polyurethane resin, water-based acrylic resin and water-based epoxy resin. Furthermore, the softening temperature of the low-melting-point glass powder is 350°C and the melting point is 500°C. Furthermore, the preparation method of the terpolymer is as follows: (1) taking hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate, adding ethanol aqueous solution, stirring and copolymerizing for 30-50 minutes to obtain a terpolymer solution; (2) removing the solvent from the terpolymer solution and spray drying the solution to obtain the terpolymer. Furthermore, the molar ratio of hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate is 45:(49-51):(4-6). Furthermore, the preparation method of the modified boron nitride nanosheets is as follows: Step 1: 0.5 g of boron nitride nanosheets were dispersed in 200 mL of tannic acid aqueous solution, stirred at 300 rpm for 20 min, and then ultrasonically treated at 100 W for 30 min; Step 2: Add PBS buffer, adjust the pH to 7.4, add 0.5 mL of ferric chloride aqueous solution and stir for 45 seconds; Step 3: Centrifuge at a speed of 3000 rpm for 8 minutes, filter, wash, and then dry the filter cake to obtain modified boron nitride nanosheets. Furthermore, the concentration of the tannic acid aqueous solution is 0.2 mg / mL; the concentration of the ferric chloride aqueous solution is 6 mg / mL. The preparation method of the above-mentioned high-efficiency flame-retardant self-healing coating comprises the following steps: take 100 parts of aqueous copolymer, 10-15 parts of terpolymer, 5-10 parts of low-melting point glass powder, 3-8 parts of modified boron nitride nanosheets, mix and stir, add 2-3 parts of defoaming agent, and stir for 40 minutes to obtain a high-efficiency flame-retardant self-healing coating. Beneficial effects: 1. The present invention adds a terpolymer, which is copolymerized by hydroxyethyl acrylate, vinylphosphonic acid and methacrylic acid dopamine. Through the interaction between the benzene ring and the catechol group, a strong adhesion to the substrate is formed. At the same time, extensive hydrogen bonds and other non-covalent interactions are formed between the terpolymer chains, which can be quickly self-healed at room temperature through a series of dynamic non-covalent interactions. The self-healing property enables the surface coating to spontaneously restore its protective function after damage and play its function in an easily damaged external environment. In addition, it can quickly form a dense, structurally complete carbon layer when it encounters fire, and can dilute the combustible gas, and suppress the chain reaction by releasing phosphorus-containing free radicals to quench the active free radicals in the gas phase, greatly improving the flame retardancy of the material. 2. The low-melting-point glass powder added in the present invention softens when the temperature is higher than 350°C, and finally melts completely at 650°C to form a flowing melt, which acts as a high-temperature adhesive to fill the macro cracks appearing on the surface of the carbon layer formed by the terpolymer, and finally forms a dense and complete ceramic protective layer to improve the flame retardancy. 3. The modified boron nitride nanosheets in the present invention can cooperate with the low-melting point glass powder to improve the flame retardancy. At the same time, the surface coating after modification contains phenolic hydroxyl groups that can undergo a ring-opening reaction with epoxy groups, which can improve the interface compatibility with the substrate. DETAILED DESCRIPTION Example 1 The preparation method of modified boron nitride nanosheets is as follows: Step 1: 0.5 g of boron nitride nanosheets were dispersed in 200 mL of 0.2 mg / mL tannic acid aqueous solution, stirred at 300 rpm for 20 min, and then ultrasonically treated at 100 W for 30 min; Step 2: Add PBS buffer, adjust the pH to 7.4, add 0.5 mL of 6 mg / mL ferric chloride aqueous solution and stir for 45 seconds; Step 3: Centrifuge at a speed of 3000 rpm for 8 minutes, filter, wash, and then dry the filter cake to obtain modified boron nitride nanosheets. Example 2 A method for preparing a highly efficient flame-retardant self-repairing coating comprises the following steps: 100 parts of waterborne polyurethane resin, 10 parts of terpolymer, 8 parts of low-melting-point glass powder, and 6 parts of modified boron nitride nanosheets are mixed and stirred, 3 parts of defoaming agent are added, and the highly efficient flame-retardant self-repairing coating is obtained after stirring for 40 minutes. The softening temperature of the low-melting-point glass powder is 350°C and the melting point is 500°C. The preparation method of the terpolymer is as follows: (1) taking hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate, adding ethanol aqueous solution, stirring and copolymerizing for 40 minutes, and obtaining a terpolymer solution; the molar ratio of hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate is 45:50:5; (2) removing the solvent from the terpolymer solution and spray drying, and obtaining the terpolymer. Example 3 A method for preparing a highly efficient flame-retardant self-repairing coating comprises the following steps: 100 parts of waterborne polyurethane resin, 13 parts of terpolymer, 8 parts of low-melting-point glass powder, and 6 parts of modified boron nitride nanosheets are mixed and stirred, 3 parts of defoamer are added, and the highly efficient flame-retardant self-repairing coating is obtained after stirring for 40 minutes. The softening temperature of the low-melting-point glass powder is 350°C and the melting point is 500°C. The preparation method of the terpolymer is as follows: (1) taking hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate, adding ethanol aqueous solution, stirring and copolymerizing for 40 minutes, and obtaining a terpolymer solution; the molar ratio of hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate is 45:50:5; (2) removing the solvent from the terpolymer solution and spray drying, and obtaining the terpolymer. Example 4 A method for preparing a highly efficient flame-retardant self-repairing coating comprises the following steps: 100 parts of waterborne polyurethane resin, 15 parts of terpolymer, 8 parts of low-melting-point glass powder, and 6 parts of modified boron nitride nanosheets are mixed and stirred, 3 parts of defoamer are added, and the highly efficient flame-retardant self-repairing coating is obtained after stirring for 40 minutes. The softening temperature of the low-melting-point glass powder is 350°C and the melting point is 500°C. The preparation method of the terpolymer is as follows: (1) taking hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate, adding ethanol aqueous solution, stirring and copolymerizing for 40 minutes, and obtaining a terpolymer solution; the molar ratio of hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate is 45:50:5; (2) removing the solvent from the terpolymer solution and spray drying, and obtaining the terpolymer. Example 5 A method for preparing a highly efficient flame-retardant self-repairing coating comprises the following steps: 100 parts of waterborne polyurethane resin, 13 parts of terpolymer, 5 parts of low-melting-point glass powder, and 6 parts of modified boron nitride nanosheets are mixed and stirred, 3 parts of defoaming agent are added, and the highly efficient flame-retardant self-repairing coating is obtained after stirring for 40 minutes. The softening temperature of the low-melting-point glass powder is 350°C and the melting point is 500°C. The preparation method of the terpolymer is as follows: (1) taking hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate, adding ethanol aqueous solution, stirring and copolymerizing for 40 minutes, and obtaining a terpolymer solution; the molar ratio of hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate is 45:50:5; (2) removing the solvent from the terpolymer solution and spray drying, and obtaining the terpolymer. Example 6 A method for preparing a highly efficient flame-retardant self-repairing coating comprises the following steps: 100 parts of waterborne polyurethane resin, 13 parts of terpolymer, 10 parts of low-melting-point glass powder, and 6 parts of modified boron nitride nanosheets are mixed and stirred, 3 parts of defoamer are added, and the highly efficient flame-retardant self-repairing coating is obtained after stirring for 40 minutes. The softening temperature of the low-melting-point glass powder is 350°C and the melting point is 500°C. The preparation method of the terpolymer is as follows: (1) taking hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate, adding ethanol aqueous solution, stirring and copolymerizing for 40 minutes, and obtaining a terpolymer solution; the molar ratio of hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate is 45:50:5; (2) removing the solvent from the terpolymer solution and spray drying, and obtaining the terpolymer. Example 7 A method for preparing a highly efficient flame-retardant self-repairing coating comprises the following steps: 100 parts of waterborne polyurethane resin, 13 parts of terpolymer, 8 parts of low-melting-point glass powder, and 3 parts of modified boron nitride nanosheets are mixed and stirred, 3 parts of defoamer are added, and the highly efficient flame-retardant self-repairing coating is obtained after stirring for 40 minutes. The softening temperature of the low-melting-point glass powder is 350°C and the melting point is 500°C. The preparation method of the terpolymer is as follows: (1) taking hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate, adding ethanol aqueous solution, stirring and copolymerizing for 40 minutes, and obtaining a terpolymer solution; the molar ratio of hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate is 45:50:5; (2) removing the solvent from the terpolymer solution and spray drying, and obtaining the terpolymer. Example 8 A method for preparing a highly efficient flame-retardant self-repairing coating comprises the following steps: 100 parts of waterborne polyurethane resin, 13 parts of terpolymer, 8 parts of low-melting-point glass powder, and 8 parts of modified boron nitride nanosheets are mixed and stirred, 3 parts of defoamer are added, and the highly efficient flame-retardant self-repairing coating is obtained after stirring for 40 minutes. The softening temperature of the low-melting-point glass powder is 350°C and the melting point is 500°C. The preparation method of the terpolymer is as follows: (1) taking hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate, adding ethanol aqueous solution, stirring and copolymerizing for 40 minutes, and obtaining a terpolymer solution; the molar ratio of hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate is 45:50:5; (2) removing the solvent from the terpolymer solution and spray drying, and obtaining the terpolymer. Example 9 A method for preparing a highly efficient flame-retardant self-repairing coating comprises the following steps: 100 parts of waterborne polyurethane resin, 13 parts of terpolymer, 8 parts of low-melting-point glass powder, and 6 parts of modified boron nitride nanosheets are mixed and stirred, 3 parts of defoamer are added, and the highly efficient flame-retardant self-repairing coating is obtained after stirring for 40 minutes. The softening temperature of the low-melting-point glass powder is 350°C and the melting point is 500°C. The preparation method of the terpolymer is as follows: (1) taking hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate, adding ethanol aqueous solution, stirring and copolymerizing for 40 minutes, and obtaining a terpolymer solution; the molar ratio of hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate is 45:49:6; (2) removing the solvent from the terpolymer solution and spray drying, and obtaining the terpolymer. Example 10 A method for preparing a highly efficient flame-retardant self-repairing coating comprises the following steps: 100 parts of waterborne polyurethane resin, 13 parts of terpolymer, 8 parts of low-melting-point glass powder, and 6 parts of modified boron nitride nanosheets are mixed and stirred, 3 parts of defoamer are added, and the highly efficient flame-retardant self-repairing coating is obtained after stirring for 40 minutes. The softening temperature of the low-melting-point glass powder is 350°C and the melting point is 500°C. The preparation method of the terpolymer is as follows: (1) taking hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate, adding ethanol aqueous solution, stirring and copolymerizing for 40 minutes, and obtaining a terpolymer solution; the molar ratio of hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate is 45:51:4; (2) removing the solvent from the terpolymer solution and spray drying, and obtaining the terpolymer. Comparative Example 1 The difference between this embodiment and embodiment 3 is that no terpolymer is added, specifically as follows: A method for preparing a highly efficient flame-retardant self-repairing coating comprises the following steps: 100 parts of waterborne polyurethane resin, 8 parts of low-melting-point glass powder, and 6 parts of modified boron nitride nanosheets are mixed and stirred, 3 parts of defoaming agent are added, and the highly efficient flame-retardant self-repairing coating is obtained after stirring for 40 minutes. The softening temperature of the low-melting-point glass powder is 350°C and the melting point is 500°C. Comparative Example 2 The difference between this embodiment and embodiment 3 is that no low melting point glass powder is added, specifically as follows: A method for preparing a high-efficiency flame-retardant self-repairing coating comprises the following steps: taking 100 parts of waterborne polyurethane resin, 13 parts of terpolymer, and 6 parts of modified boron nitride nanosheets, mixing and stirring, adding 3 parts of defoaming agent, and stirring for 40 minutes to obtain the high-efficiency flame-retardant self-repairing coating. The preparation method of the terpolymer is as follows: (1) taking hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate, adding ethanol aqueous solution, stirring and copolymerizing for 40 minutes, and obtaining a terpolymer solution; the molar ratio of hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate is 45:50:5; (2) removing the solvent from the terpolymer solution and spray drying, and obtaining the terpolymer. Comparative Example 3 The difference between this embodiment and embodiment 3 is that no modified boron nitride nanosheets are added, specifically as follows: A method for preparing a highly efficient flame-retardant self-repairing coating comprises the following steps: 100 parts of waterborne polyurethane resin, 13 parts of terpolymer, and 8 parts of low-melting-point glass powder are mixed and stirred, 3 parts of defoamer are added, and the highly efficient flame-retardant self-repairing coating is obtained after stirring for 40 minutes. The softening temperature of the low-melting-point glass powder is 350°C and the melting point is 500°C. The preparation method of the terpolymer is as follows: (1) taking hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate, adding ethanol aqueous solution, stirring and copolymerizing for 40 minutes, and obtaining a terpolymer solution; the molar ratio of hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate is 45:50:5; (2) removing the solvent from the terpolymer solution and spray drying, and obtaining the terpolymer. Comparative Example 4 The difference between this embodiment and embodiment 3 is that the terpolymer is changed into a binary copolymer, as follows: A method for preparing a highly efficient flame-retardant self-repairing coating comprises the following steps: 100 parts of waterborne polyurethane resin, 13 parts of binary copolymer, 8 parts of low-melting-point glass powder, and 6 parts of modified boron nitride nanosheets are mixed and stirred, 3 parts of defoaming agent are added, and the highly efficient flame-retardant self-repairing coating is obtained after stirring for 40 minutes. The softening temperature of the low-melting-point glass powder is 350°C and the melting point is 500°C. The preparation method of the binary copolymer is as follows: (1) taking hydroxyethyl acrylate and vinyl phosphonic acid, adding ethanol aqueous solution, stirring and copolymerizing for 40 minutes, and obtaining a binary copolymer solution; the molar ratio of hydroxyethyl acrylate to vinyl phosphonic acid is 45:50; (2) Removing the solvent from the binary copolymer solution and spray drying the solution to obtain the binary copolymer. The high-efficiency flame-retardant self-repairing coating prepared in the above embodiment was coated on the treated wooden board, and after UV curing, a coating with a thickness of 200 μm was prepared. The substrate adhesion (shear strength) and flame retardant performance were tested, and the results are shown in Table 1 below: Table 1

Claims

1. A highly efficient flame retardant self-repairing coating, characterized in that: The composition comprises the following components in parts by weight: water-based copolymer, terpolymer, low melting point glass powder, and modified boron nitride nanosheets; The terpolymer is prepared by copolymerization of hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate.

2. The high-efficiency flame-retardant self-repairing coating according to claim 1, characterized in that: The water-based copolymer includes water-based polyurethane resin, water-based acrylic resin and water-based epoxy resin.

3. The high-efficiency flame-retardant self-repairing coating according to claim 1, characterized in that: The softening temperature of the low-melting-point glass powder is 350°C and the melting point is 500°C.

4. The high-efficiency flame-retardant self-repairing coating according to claim 1, characterized in that: The preparation method of the terpolymer is as follows: (1) taking hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate, adding ethanol aqueous solution, stirring and copolymerizing for 30-50 minutes to obtain a terpolymer solution; (2) removing the solvent from the terpolymer solution and spray drying the solution to obtain the terpolymer.

5. The high-efficiency flame-retardant self-repairing coating according to claim 4, characterized in that: The molar ratio of hydroxyethyl acrylate, vinylphosphonic acid and dopamine methacrylate is 45:(49-51):(4-6).

6. The high-efficiency flame-retardant self-repairing coating according to claim 1, characterized in that: The preparation method of the modified boron nitride nanosheets is as follows: Step 1: 0.5 g of boron nitride nanosheets were dispersed in 200 mL of tannic acid aqueous solution, stirred at 300 rpm for 20 min, and then ultrasonically treated at 100 W for 30 min; Step 2: Add PBS buffer, adjust the pH to 7.4, add 0.5 mL of ferric chloride aqueous solution and stir for 45 seconds; Step 3: Centrifuge at a speed of 3000 rpm for 8 minutes, filter, wash, and then dry the filter cake to obtain modified boron nitride nanosheets.

7. The high-efficiency flame-retardant self-repairing coating according to claim 6, characterized in that: The concentration of the tannic acid aqueous solution is 0.2 mg / mL; the concentration of the ferric chloride aqueous solution is 6 mg / mL.

8. A method for preparing a highly efficient flame retardant self-repairing coating according to any one of claims 1 to 7, characterized in that: The following steps are involved: Take 100 parts of water-based copolymer, 10-15 parts of terpolymer, 5-10 parts of low-melting-point glass powder, 3-8 parts of modified boron nitride nanosheets, mix and stir, add 2-3 parts of defoaming agent, and stir for 40 minutes to obtain a high-efficiency flame-retardant self-repairing coating.

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