Radiation-resistant nano coating and preparation method thereof

Abstract

The invention relates to an irradiation-resistant nano coating and a preparation method thereof, and belongs to the technical field of high polymer materials. The radiation-resistant nano coating comprises the following components in parts by weight: 15-35 parts of modified epoxy resin, 3-15 parts of barium sulfate, 3-15 parts of boron carbide, 6-8 parts of a foaming agent, 35-50 parts of expanded graphite, 7-9 parts of carbon nanotubes, 0.5-1 part of a coupling agent, 0.5-1 part of a dispersing agent and 6-10 parts of a modified flame retardant, organophosphorus in the modified flame retardant captures free radicals in combustion chains, phosphorus in phosphonitrilic chloride trimer generates a phosphoric acid or polyphosphoric acid protective film during combustion, and nitrogen releases non-combustible gas and absorbs heat; silicon nitride in the modified epoxy resin has excellent radiation resistance, atom displacement damage caused by radiation is inhibited, the modified silicon nitride and the epoxy resin form stable chemical bonds, and breakage and degradation of molecular chains are inhibited; the radiation-resistant nano coating prepared by the invention not only has a good radiation-resistant effect, but also has an excellent flame-retardant effect.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and particularly relates to a radiation-resistant nano coating and a preparation method thereof. Background Art

[0002] With the widespread use of high-radiation equipment, research on radiation-resistant materials has attracted significant attention. Radiation-resistant nanocoatings are specialized protective materials developed specifically for use in high-radiation environments such as nuclear reactors, nuclear power plants, and space technology. Using nanotechnology, they enhance the coating's radiation resistance, extending equipment life and ensuring safety. They are now widely used in housing construction, automotive, petrochemical, military equipment, and high-temperature equipment.

[0003] However, although the nanocoating made of epoxy resin has excellent advantages such as corrosion resistance and wear resistance, it has the problems of brittleness and low toughness, which limits its application. In addition, although the epoxy resin nanocoating itself has certain flame retardancy, with the continuous improvement of actual application needs, its own flame retardancy can no longer meet current needs. Therefore, the research and development of radiation-resistant nanocoatings with excellent performance has important practical significance and application value. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a radiation-resistant nano-coating and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions: A radiation-resistant nano coating and a preparation method thereof, comprising the following raw materials in parts by weight: 15-35 parts of a modified epoxy resin, 3-15 parts of barium sulfate, 3-15 parts of boron carbide, 6-8 parts of a foaming agent, 35-50 parts of expanded graphite, 7-9 parts of carbon nanotubes, 0.5-1 part of a coupling agent, 0.5-1 part of a dispersant, and 6-10 parts of a modified flame retardant; The coupling agent is 3-aminopropyltriethoxysilane; The foaming agent is melamine; The dispersant is sodium hexametaphosphate.

[0006] The modified flame retardant is prepared by the following method: Step A1: Tetrahydrofuran, anhydrous potassium carbonate, and vanillin were mixed uniformly, stirred at room temperature for 1 hour, and then hexachlorocyclotriphosphazene was slowly added dropwise over 30 minutes. The mixture was heated to 65°C and reacted for 24 hours. The mixture was filtered, washed, and dried under vacuum at 60°C to obtain the compound. Furthermore, the usage ratio of tetrahydrofuran, anhydrous potassium carbonate, vanillin, and hexachlorocyclotriphosphazene is 300 mL: 13.8-14.2 g: 0.06-0.12 mol: 0.01-0.02 mol; First, the chlorine atom of hexachlorocyclotriphosphazene reacts with the hydroxyl group of vanillin to prepare the compound; Step A2: The compound, o-aminophenol, and 1,4-dioxane were mixed uniformly and reacted at 30°C for 2 hours. After the reaction, the mixture was cooled to room temperature, filtered, washed, and dried under vacuum at 80°C for 6 hours to obtain a pre-product; Furthermore, the ratio of the compound, o-aminophenol, and 1,4-dioxane is 0.01-0.02 mol: 0.06-0.12 mol: 120-150 mL; Secondly, the aldehyde group of the compound reacts with the amino group of o-aminophenol to prepare a pre-product; Step A3: mixing the preproduct, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and 1,4-dioxane, reacting at 30° C. for 16 hours, filtering, washing, and vacuum drying at 80° C. for 24 hours to obtain a modified flame retardant; Furthermore, the ratio of the preproduct, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and 1,4-dioxane is 0.01-0.02 mol: 0.06-0.12 mol: 130-150 mL; Finally, the pre-product is reacted with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to prepare a modified flame retardant.

[0007] The modified epoxy resin is prepared by the following method: Step B1: Place nano-Si3N4 in a vacuum drying oven at 120°C for activation treatment for 2.5 hours, then add 3-aminopropyltriethoxysilane, anhydrous ethanol and deionized water, mix, and ultrasonically stir for 20 minutes. Adjust the pH of the system to 4-7, and magnetically stir at 70°C for 2 hours. After the reaction is completed, filter, wash, and dry at 120°C to obtain modified silicon nitride; Furthermore, the usage ratio of nano-Si3N4, 3-aminopropyltriethoxysilane, anhydrous ethanol, and deionized water is 0.01-0.03 mol: 0.01-0.03 mol: 9-27 mL: 1-3 mL; First, nano-Si3N4 is modified with 3-aminopropyltriethoxysilane to obtain modified silicon nitride; Step B2: uniformly mixing the modified silicon nitride, ethanol, and epoxy resin, stirring at high speed for 15 minutes, reacting at 70° C. for 1 hour, and then ultrasonically oscillating for 30 minutes, filtering, washing, and drying to obtain a modified epoxy resin; Furthermore, the ratio of modified silicon nitride, ethanol, and epoxy resin is 0.01-0.03 mol: 20-30 mL: 0.01-0.03 mol; Finally, the modified epoxy resin is prepared by reacting the amino group of the modified silicon nitride with the epoxy group of the epoxy resin.

[0008] A method for preparing a radiation-resistant nanocoating comprises the following steps: S1. Ultrasonic dispersion of barium sulfate, boron carbide, and a coupling agent, followed by addition of expanded graphite and carbon nanotubes, to obtain a mixed material; S2. The mixed material, modified epoxy resin, foaming agent, dispersant and modified flame retardant are mixed and stirred for 10 minutes. After coating, the mixture is pre-cured at 80° C. for 1 hour and then cured at 120° C. for 2 hours to obtain a radiation-resistant nano coating.

[0009] Beneficial effects of the present invention: The radiation-resistant nano coating of the present invention has good radiation resistance and excellent flame retardant effect, thereby further extending the service life.

[0010] The organic phosphorus in the modified flame retardant prepared by the present invention decomposes in the gas phase to generate free radicals, which capture the free radicals in the combustion chain to terminate the reaction. At the same time, it catalyzes the dehydration and carbonization of epoxy resin in the condensed phase to form a dense carbon layer, which blocks oxygen supply and heat transfer, and synergizes with nitrogen to improve flame retardant efficiency. Hexachlorocyclotriphosphazene exhibits excellent thermal stability due to the conjugated effect of the phosphorus and nitrogen main chains. When burning, the phosphorus element generates a phosphoric acid or polyphosphoric acid protective film to isolate oxygen, and the nitrogen element releases non-combustible gas to dilute the oxygen concentration and absorb a large amount of heat to slow down the combustion. The material heats up quickly, forming a glassy or stable foam covering layer at high temperatures to further insulate against heat and oxygen. Furthermore, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, as a phosphaphenanthrene compound with high thermal stability, promotes the formation of a dense and continuous carbon layer during combustion, isolating oxygen and blocking the exchange of heat and combustible gases, thereby enhancing the flame retardant effect and extending the service life of the material. Furthermore, the modified flame retardant prepared by the present invention is halogen-free, can reduce environmental pollution and damage to the ecosystem, is harmless to human health, and achieves sustainable development.

[0011] In the modified epoxy resin prepared by the present invention, nano-silicon nitride can be uniformly dispersed in the epoxy resin after being surface-modified by 3-aminopropyltriethoxysilane. The amino groups introduced by the modification form stable chemical bonds with the epoxy resin matrix. Such chemical bonds enhance the structural stability of the coating under irradiation, effectively inhibit the molecular chain breakage and degradation caused by irradiation, reduce interface defects, and significantly improve the tensile strength of the composite material. The covalent bond crystal structure of silicon nitride has excellent radiation resistance, which can effectively inhibit atomic displacement damage caused by irradiation and reduce the formation of vacancies and interstitial defects, thereby reducing the wear quality of the coating and extending its service life. In addition, nano-Si3N4 itself has high thermal conductivity and high temperature resistance. After modification, the interfacial thermal resistance with the epoxy resin is reduced, forming an efficient heat conduction path, so that the coating maintains dimensional stability under high temperature or thermal cycle environments, reduces the thermal expansion coefficient, and thus reduces the risk of cracking caused by thermal stress. DETAILED DESCRIPTION

[0012] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0013] Example 1: A method for preparing a radiation-resistant nanocoating, comprising the following steps: S1. Weigh the raw materials by weight: 15 parts of modified epoxy resin (prepared in this example), 3 parts of barium sulfate, 3 parts of boron carbide, 6 parts of foaming agent, 35 parts of expanded graphite, 7 parts of carbon nanotubes, 0.5 parts of 3-aminopropyltriethoxysilane, 0.5 parts of dispersant, and 6 parts of modified flame retardant (prepared in this example); ultrasonically disperse the barium sulfate, boron carbide, and 3-aminopropyltriethoxysilane, then add the expanded graphite and carbon nanotubes and mix well to obtain a mixed material; S2, mixing the mixed material, modified epoxy resin, melamine, sodium hexametaphosphate and modified flame retardant for 10 minutes, and then pre-curing at 80° C. for 1 hour and curing at 120° C. for 2 hours after coating to obtain a radiation-resistant nano coating; The modified flame retardant is prepared by the following method: Step A1: Mix 300 mL of tetrahydrofuran, 13.8 g of anhydrous potassium carbonate, and 0.06 mol of vanillin, stir at room temperature for 1 hour, then slowly add 0.01 mol of hexachlorocyclotriphosphazene dropwise over 30 minutes. Heat to 65°C, react for 24 hours, filter, wash, and dry in vacuo at 60°C to obtain the compound. Step A2: 0.01 mol of the compound, 0.06 mol of o-aminophenol, and 120 mL of 1,4-dioxane were mixed uniformly, and the mixture was reacted at 30°C for 2 h. After the reaction, the mixture was cooled to room temperature, filtered, washed, and dried under vacuum at 80°C for 6 h to obtain a pre-product; Step A3: 0.01 mol of the preproduct, 0.06 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and 130 mL of 1,4-dioxane were mixed and reacted at 30° C. for 16 h. After the reaction, the mixture was filtered, washed, and vacuum-dried at 80° C. for 24 h to obtain a modified flame retardant; The modified epoxy resin is prepared by the following method: Step B1: 0.01 mol of nano-Si3N4 was placed in a vacuum drying oven at 120°C for activation treatment for 2.5 hours, and then 0.01 mol of 3-aminopropyltriethoxysilane, 9 mL of anhydrous ethanol and 1 mL of deionized water were added and mixed. The mixture was ultrasonically stirred for 20 minutes, and the pH of the system was adjusted to 4. The mixture was magnetically stirred at 70°C for 2 hours. After the reaction was completed, the mixture was filtered, washed, and dried at 120°C to obtain modified silicon nitride. Step B2: 0.01 mol of modified silicon nitride, 20 mL of ethanol and 0.01 mol of epoxy resin were mixed evenly, stirred at high speed for 15 minutes, reacted at 70°C for 1 hour, and then ultrasonically vibrated for 30 minutes, filtered, washed, and dried to obtain a modified epoxy resin.

[0014] Example 2: A method for preparing a radiation-resistant nanocoating, comprising the following steps: S1. Weigh the raw materials by weight: 25 parts of modified epoxy resin (prepared in this example), 9 parts of barium sulfate, 9 parts of boron carbide, 7 parts of foaming agent, 42.5 parts of expanded graphite, 8 parts of carbon nanotubes, 0.75 parts of 3-aminopropyltriethoxysilane, 0.75 parts of dispersant, and 8 parts of modified flame retardant (prepared in this example); ultrasonically disperse the barium sulfate, boron carbide, and 3-aminopropyltriethoxysilane, then add the expanded graphite and carbon nanotubes and mix thoroughly to obtain a mixed material; S2, mixing the mixed material, modified epoxy resin, melamine, sodium hexametaphosphate and modified flame retardant for 10 minutes, and then pre-curing at 80° C. for 1 hour and curing at 120° C. for 2 hours after coating to obtain a radiation-resistant nano coating; The modified flame retardant is prepared by the following method: Step A1: Mix 300 mL of tetrahydrofuran, 14.0 g of anhydrous potassium carbonate, and 0.09 mol of vanillin, stir at room temperature for 1 hour, then slowly add 0.015 mol of hexachlorocyclotriphosphazene dropwise over 30 minutes, heat to 65°C, react for 24 hours, filter, wash, and dry in vacuo at 60°C to obtain the compound; Step A2: 0.015 mol of the compound, 0.09 mol of o-aminophenol, and 135 mL of 1,4-dioxane were mixed uniformly, reacted at 30°C for 2 h, and after completion of the reaction, cooled to room temperature, filtered, washed, and dried under vacuum at 80°C for 6 h to obtain a pre-product; Step A3: 0.015 mol of the preproduct, 0.09 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and 145 mL of 1,4-dioxane were mixed and reacted at 30° C. for 16 h. After the reaction, the mixture was filtered, washed, and vacuum-dried at 80° C. for 24 h to obtain a modified flame retardant; The modified epoxy resin is prepared by the following method: Step B1: 0.02 mol of nano-Si3N4 was placed in a vacuum drying oven for activation treatment at 120°C for 2.5 hours, and then 0.02 mol of 3-aminopropyltriethoxysilane, 18 mL of anhydrous ethanol and 2 mL of deionized water were added and mixed, and ultrasonic mechanical stirring was performed for 20 minutes. The pH of the system was adjusted to 5.5, and magnetic stirring was performed at 70°C for 2 hours. After the reaction was completed, the mixture was filtered, washed, and dried at 120°C to obtain modified silicon nitride; Step B2: 0.02 mol of modified silicon nitride, 25 mL of ethanol and 0.02 mol of epoxy resin were mixed evenly, stirred at high speed for 15 minutes, reacted at 70°C for 1 hour, and then ultrasonically vibrated for 30 minutes, filtered, washed, and dried to obtain a modified epoxy resin.

[0015] Example 3: A method for preparing a radiation-resistant nanocoating, comprising the following steps: S1. Weigh the raw materials by weight: 35 parts of modified epoxy resin (prepared in this example), 15 parts of barium sulfate, 15 parts of boron carbide, 8 parts of foaming agent, 50 parts of expanded graphite, 9 parts of carbon nanotubes, 1 part of 3-aminopropyltriethoxysilane, 1 part of dispersant, and 10 parts of modified flame retardant (prepared in this example); ultrasonically disperse the barium sulfate, boron carbide, and 3-aminopropyltriethoxysilane, then add the expanded graphite and carbon nanotubes and mix well to obtain a mixed material; S2, mixing the mixed material, modified epoxy resin, melamine, sodium hexametaphosphate and modified flame retardant for 10 minutes, and then pre-curing at 80° C. for 1 hour and curing at 120° C. for 2 hours after coating to obtain a radiation-resistant nano coating; The modified flame retardant is prepared by the following method: Step A1: Mix 300 mL of tetrahydrofuran, 14.2 g of anhydrous potassium carbonate, and 0.12 mol of vanillin, stir at room temperature for 1 hour, then slowly add 0.02 mol of hexachlorocyclotriphosphazene dropwise over 30 minutes, heat to 65°C, react for 24 hours, filter, wash, and dry in vacuo at 60°C to obtain the compound; Step A2: 0.02 mol of the compound, 0.12 mol of o-aminophenol, and 150 mL of 1,4-dioxane were mixed uniformly, and the mixture was reacted at 30°C for 2 h. After the reaction, the mixture was cooled to room temperature, filtered, washed, and dried in vacuo at 80°C for 6 h to obtain a pre-product; Step A3: 0.02 mol of the preproduct, 0.12 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and 150 mL of 1,4-dioxane were mixed and reacted at 30° C. for 16 h. After the reaction, the mixture was filtered, washed, and vacuum-dried at 80° C. for 24 h to obtain a modified flame retardant; The modified epoxy resin is prepared by the following method: Step B1: 0.03 mol of nano-Si3N4 was placed in a vacuum drying oven for activation treatment at 120°C for 2.5 hours, and then 0.03 mol of 3-aminopropyltriethoxysilane, 27 mL of anhydrous ethanol and 3 mL of deionized water were added and mixed, and ultrasonic mechanical stirring was performed for 20 minutes. The pH of the system was adjusted to 7, and magnetic stirring was performed at 70°C for 2 hours. After the reaction was completed, the mixture was filtered, washed, and dried at 120°C to obtain modified silicon nitride; Step B2: 0.03 mol of modified silicon nitride, 30 mL of ethanol and 0.03 mol of epoxy resin were mixed evenly, stirred at high speed for 15 minutes, reacted at 70°C for 1 hour, and then ultrasonically vibrated for 30 minutes, filtered, washed, and dried to obtain a modified epoxy resin.

[0016] Comparative Example 1: This comparative example is a radiation-resistant nanocoating. The difference from Example 3 is that an equal amount of magnesium hydroxide is used instead of the modified flame retardant prepared in Example 3, and the rest are the same.

[0017] Comparative Example 2: This comparative example is a radiation-resistant nanocoating. The difference from Example 3 is that an equal amount of epoxy resin is used instead of the modified epoxy resin prepared in Example 3, and the rest are the same.

[0018] Performance Testing: The radiation-resistant nanocoatings prepared in Examples 1-3 and Comparative Examples 1-2 were cut into standard test sizes and tested for radiation resistance according to NB / T 20133.3-2012. Vertical burning performance was tested using UL94. Elongation at break was measured on a material testing machine under the following test conditions: a chuck distance of 100 mm, a test speed of 500 mm / min, and a preload tension of 0.09 cN / dtex. The test results are shown in Table 1 below: Table 1

[0019] It can be seen from the test data in Table 1 that the radiation-resistant nano coating prepared by the present invention has good radiation resistance effect. It can also be seen from Table 1 that the radiation-resistant nano coating prepared by the present invention has good flame retardant effect and prolongs the service life.

[0020] The above content is merely an example and explanation of the concept of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined in this book, they should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a radiation-resistant nanocoating, characterized in that: The specific steps include: S1. Weigh the raw materials by weight: 15-35 parts of modified epoxy resin, 3-15 parts of barium sulfate, 3-15 parts of boron carbide, 6-8 parts of foaming agent, 35-50 parts of expanded graphite, 7-9 parts of carbon nanotubes, 0.5-1 part of coupling agent, 0.5-1 part of dispersant, and 6-10 parts of modified flame retardant; ultrasonically disperse the barium sulfate, boron carbide and coupling agent, then add the expanded graphite and carbon nanotubes and mix well to obtain a mixed material; S2, mixing the mixed material, modified epoxy resin, foaming agent, dispersant and modified flame retardant for 10 minutes, and then pre-curing at 80° C. for 1 hour and curing at 120° C. for 2 hours after coating to obtain a radiation-resistant nano coating; The modified flame retardant is prepared by the following method: Step A1: Tetrahydrofuran, anhydrous potassium carbonate, and vanillin were mixed uniformly, stirred at room temperature for 1 hour, and then hexachlorocyclotriphosphazene was slowly added dropwise over 30 minutes. The mixture was heated to 65°C and reacted for 24 hours. The mixture was filtered, washed, and dried under vacuum at 60°C to obtain the compound. Step A2: The compound, o-aminophenol, and 1,4-dioxane were mixed uniformly and reacted at 30°C for 2 hours. After the reaction, the mixture was cooled to room temperature, filtered, washed, and dried under vacuum at 80°C for 6 hours to obtain a pre-product; Step A3: The preproduct, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and 1,4-dioxane were mixed and reacted at 30° C. for 16 hours. After the reaction, the mixture was filtered, washed, and vacuum-dried at 80° C. for 24 hours to obtain a modified flame retardant.

2. The method for preparing a radiation-resistant nanocoating according to claim 1, characterized in that: In step A1, the usage ratio of tetrahydrofuran, anhydrous potassium carbonate, vanillin, and hexachlorocyclotriphosphazene is 300 mL: 13.8-14.2 g: 0.06-0.12 mol: 0.01-0.02 mol.

3. The method for preparing a radiation-resistant nanocoating according to claim 1, characterized in that: The usage ratio of the compound in step A2, o-aminophenol, and 1,4-dioxane is 0.01-0.02 mol: 0.06-0.12 mol: 120-150 mL.

4. The method for preparing a radiation-resistant nanocoating according to claim 1, characterized in that: In step A3, the usage ratio of the preproduct, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and 1,4-dioxane is 0.01-0.02 mol: 0.06-0.12 mol: 130-150 mL.

5. The method for preparing a radiation-resistant nanocoating according to claim 1, characterized in that: The modified epoxy resin is prepared by the following method: Step B1: Place nano-Si3N4 in a vacuum drying oven at 120°C for activation treatment for 2.5 hours, then add 3-aminopropyltriethoxysilane, anhydrous ethanol and deionized water, mix, and ultrasonically stir for 20 minutes. Adjust the pH of the system to 4-7, and magnetically stir at 70°C for 2 hours. After the reaction is completed, filter, wash, and dry at 120°C to obtain modified silicon nitride; Step B2: The modified silicon nitride, ethanol and epoxy resin were mixed evenly, stirred at high speed for 15 minutes, reacted at 70° C. for 1 hour, and then ultrasonically vibrated for 30 minutes, filtered, washed and dried to obtain a modified epoxy resin.

6. The method for preparing a radiation-resistant nanocoating according to claim 5, characterized in that: In step B1, the usage ratio of nano-Si3N4, 3-aminopropyltriethoxysilane, anhydrous ethanol, and deionized water is 0.01-0.03 mol: 0.01-0.03 mol: 9-27 mL: 1-3 mL.

7. The method for preparing a radiation-resistant nanocoating according to claim 5, characterized in that: In step B2, the usage ratio of modified silicon nitride, ethanol, and epoxy resin is 0.01-0.03 mol: 20-30 mL: 0.01-0.03 mol.

8. The method for preparing a radiation-resistant nanocoating according to claim 1, characterized in that: The coupling agent is 3-aminopropyltriethoxysilane, the foaming agent is melamine, and the dispersant is sodium hexametaphosphate.

9. A radiation-resistant nanocoating, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 8.

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