Flame-retardant modified bentonite composite coating and preparation method thereof

Abstract

The application belongs to the technical field of paint and specifically relates to a kind of fire-retardant modified bentonite composite coating and a preparation method thereof.The coating is composed of component A and component B;the mass ratio of component A to component B is 1:(0.3-0.7);component A includes the following raw materials in parts by weight: epoxy resin 40-50 parts, diluent 15-20 parts, wear-resistant agent 1-3 parts, and char-forming agent 5-10 parts;component B includes the following raw materials in parts by weight: curing agent 20-30 parts, curing accelerator 1-3 parts, modified bentonite 5-10 parts, leveling agent 0.3-0.5 parts, and defoaming agent 0.1-0.5 parts.The coating has excellent mechanical properties, corrosion resistance, fire-retardant properties, and wear resistance.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically relating to a flame-retardant modified bentonite composite coating and its preparation method. Background Technology

[0002] Bentonite, a natural layered silicate mineral, is widely used in architectural coatings, fire-retardant coatings, and industrial anti-corrosion coatings due to its unique water absorption and swelling properties, cation exchange capacity, and good dispersibility. Introducing bentonite as an inorganic filler into coating systems can effectively improve the suspension stability, thixotropy, and storage stability of the coatings, while also imparting certain physical barrier and flame-retardant properties to the coating, thereby reducing production costs and meeting the current development needs of green and environmentally friendly coatings.

[0003] However, natural bentonite faces numerous technical bottlenecks in practical applications. First, the surface of bentonite flakes is rich in hydrophilic silanol groups, resulting in poor interfacial compatibility with organic resin matrices. This leads to agglomeration in coatings, causing uneven dispersion. This uneven dispersion not only creates defects and stress concentration points within the coating, significantly reducing its mechanical properties, but also drastically decreases its wear resistance due to weak filler-matrix interfacial bonding, making it difficult to meet long-term use requirements under high-friction and high-wear environments. Second, although bentonite itself is a silicate mineral with certain thermal stability and oxygen barrier properties, its flame retardant efficiency is low. When used alone, it is difficult to quickly form a dense, continuous expanded char layer at high temperatures, failing to effectively block heat transfer and the escape of combustible gases, thus making it difficult to meet the stringent requirements of high flame retardant ratings for coatings in modern construction, rail transportation, and industrial equipment.

[0004] Currently, existing technologies typically modify bentonite using organic intercalation or simple physical blending. However, these methods often only improve a single property and fail to achieve a synergistic improvement in multiple properties. For example, while organic intercalation can improve the dispersibility of bentonite in an organic matrix, the intercalating agents are often flammable organic compounds, which can actually reduce the flame retardant properties of the coating. Conversely, adding large amounts of traditional flame retardants (such as aluminum hydroxide, magnesium hydroxide, and ammonium polyphosphate) can improve the flame retardant rating, but the excessive total filler content can further reduce the mechanical properties and wear resistance of the coating, and also presents problems such as poor compatibility with the matrix and easy migration and precipitation. Therefore, how to achieve a synergistic improvement in the wear resistance, flame retardancy, and mechanical properties of the coating while maintaining the excellent thickening and suspension properties of bentonite through scientific structural design and surface chemical modification has become a key technical problem that urgently needs to be solved in the field of bentonite composite coatings. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the first objective of this invention is to provide a flame-retardant modified bentonite composite coating that has excellent mechanical properties, corrosion resistance, flame retardancy and wear resistance.

[0006] The second objective of this invention is to provide a method for preparing flame-retardant modified bentonite composite coatings, which is simple and easy to operate.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A flame-retardant modified bentonite composite coating is composed of component A and component B; the mass ratio of component A to component B is 1:(0.3-0.7).

[0009] Component A comprises the following raw materials in parts by weight: 40-50 parts epoxy resin, 15-20 parts diluent, 1-3 parts abrasion resistant agent, and 5-10 parts charring agent.

[0010] Component B comprises the following raw materials in parts by weight: 20-30 parts curing agent, 1-3 parts curing accelerator, 5-10 parts modified bentonite, 0.3-0.5 parts leveling agent, and 0.1-0.5 parts defoamer;

[0011] The preparation process of the modified bentonite in component B is as follows:

[0012] L1: Add bentonite modified with epoxy silane coupling agent to sulfuric acid solution, stir and react, then purify to obtain hydroxylated bentonite.

[0013] L2: The hydroxylated bentonite was added to N,N-dimethylformamide. Under inert gas protection, 2,4,6-tricarboxylic acid-1,3,5-triazine, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and N-hydroxysuccinimide were added. After stirring, pentaerythritol allyl ether was added, and stirring was continued. The mixture was then purified to obtain the modified bentonite.

[0014] Preferably, in step L1, the ratio of bentonite modified with epoxy silane coupling agent to sulfuric acid solution is 1g:(10-15)mL; the mass fraction of sulfuric acid solution is 2-4%; the temperature of the stirring reaction is 60-70℃, and the time is 15-20h.

[0015] Preferably, the preparation process of the bentonite modified with the epoxy silane coupling agent is as follows:

[0016] An epoxy-silane coupling agent was added to an aqueous ethanol solution, the pH was adjusted and the solution was stirred to obtain a mixed solution 1. An acidified bentonite was added to the mixed solution 1, and the solution was purified after reaction to obtain bentonite modified with the epoxy-silane coupling agent.

[0017] Preferably, the ratio of acidified bentonite to mixed solution 1 is 1g:(100-120)mL; the epoxy silane coupling agent is KH-560; the volume fraction of the ethanol aqueous solution is 90-95%; the pH is adjusted to 4-5; the stirring time is 30-40min; the reaction temperature is 65-75℃ and the reaction time is 6-10h.

[0018] Preferably, the preparation method of the acidified bentonite is as follows:

[0019] Bentonite is added to a 6-8% hydrochloric acid solution at a ratio of 1g:(50-55)mL. The solution is then heated and refluxed for 2-3 hours to obtain the final product. The solution is then filtered, washed, and dried.

[0020] Preferably, in step L2, the mass ratio of hydroxylated bentonite, 2,4,6-tricarboxylic acid-1,3,5-triazine, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, and pentaerythritol allyl ether is 1:(0.9-1.4):(0.1-0.2):(0.2-0.4):(0.8-1.5); the stirring temperature is 100-110℃, and the stirring time is 3-5 hours; the stirring continues for 12-15 hours.

[0021] Preferably, the preparation process of the wear-resistant agent in component A is as follows:

[0022] The carbon fibers modified with silane coupling agent were added to an aqueous solution of molybdenum sulfate, followed by the addition of triethylamine and sodium thiosulfate. After heating and reaction, the mixture was purified to obtain the wear-resistant agent.

[0023] Preferably, the mass ratio of molybdenum sulfate to sodium thiosulfate in the triethylamine, silane coupling agent-modified carbon fiber, and molybdenum sulfate aqueous solution is 1:(10-13):(10-13):(5-7); the mass fraction of the molybdenum sulfate aqueous solution is 5-8%; and the heating reaction temperature is 80-90℃ and the time is 1-3h.

[0024] Preferably, the preparation process of the silane coupling agent modified carbon fiber is as follows:

[0025] A silane coupling agent was added to an aqueous ethanol solution, the pH was adjusted to 4-5, and the mixture was stirred to obtain a mixed solution 2. Carbon fibers were added to the mixed solution 2, and the mixture was reacted at 50-60℃ for 4-8 hours. After purification, the carbon fibers modified with the silane coupling agent were obtained.

[0026] Preferably, the ratio of carbon fiber to mixed solution 2 is 1g:(100-120)mL; the mass fraction of the silane coupling agent in the ethanol aqueous solution is 0.5-0.8%; the silane coupling agent is KH-560; and the stirring time is 30-40min.

[0027] Preferably, the diluent in component A is phenyl glycidyl ether or 1,4-butanediol diglycidyl ether, and the charring agent is composed of pentaerythritol and dipentaerythritol in a mass ratio of 1:1; the curing agent in component B is polyamide or polyethyleneimine, the curing accelerator is salicylic acid or phenol, the leveling agent is BYK-307, and the defoamer is BYK-054.

[0028] The preparation method of the above-mentioned flame-retardant modified bentonite composite coating includes the following steps:

[0029] S1. Mix epoxy resin, abrasion resistant agent, charring agent and diluent evenly to obtain component A;

[0030] S2. Mix the curing agent, curing accelerator, modified bentonite, leveling agent and defoamer evenly to obtain component B;

[0031] S3. Mix component A and component B evenly.

[0032] The beneficial technical effects of this invention are as follows:

[0033] 1. This invention provides a flame-retardant modified bentonite composite coating, which has excellent mechanical properties, corrosion resistance, flame retardancy and wear resistance.

[0034] 2. This invention improves the mechanical properties, flame retardant properties, and corrosion resistance of coatings by adding modified bentonite. Regarding flame retardant properties: the bentonite layers exert a physical barrier effect; during combustion, the stacked layers effectively block oxygen, inhibit the outward diffusion of combustible molecules, and slow down heat transfer; the chemically grafted 1,3,5-triazine ring decomposes upon heating, releasing inert gases such as N2, diluting the concentration of combustible gases and promoting char formation in the substrate; the pentaerythritol structure catalytically dehydrates at high temperatures, promoting the formation of a continuous and dense char layer on the paint film surface. These components together constitute a composite intumescent flame retardant system, significantly reducing the heat release rate of epoxy resin coatings, inhibiting flame spread, and reducing the release of toxic smoke. In terms of corrosion resistance and mechanical properties: the bentonite layers form a labyrinthine channel inside the paint film, which prolongs the penetration path of corrosive media such as water and chloride ions; the grafted allyl double bonds can cross-link with the epoxy resin matrix, reducing the micropores inside the paint film, thereby improving the corrosion resistance of the paint film, improving the interfacial bonding force, and enhancing the mechanical properties of the paint film.

[0035] 3. This invention improves the wear resistance of coatings by adding wear-resistant agents. The wear-resistant agent of this invention uses carbon fibers modified with silane coupling agents as a carrier, and generates nano-molybdenum disulfide in situ in an aqueous system and uniformly loads it on the surface of the carbon fibers. The carbon fibers bear the main load to improve the wear resistance of the coating, while the lamellar molybdenum disulfide plays a solid self-lubricating role. The two work synergistically to significantly improve the friction and wear performance of epoxy coatings. Attached Figure Description

[0036] Figure 1 SEM image of the wear-resistant agent obtained in Example 1;

[0037] Figure 2 SEM image of the modified bentonite obtained in Example 4. Detailed Implementation

[0038] The following is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention. Specific conditions not specified in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels.

[0039] In component A of this invention, the epoxy resin is E51; the diluent is 1,4-butanediol diglycidyl ether; and the charring agent is composed of pentaerythritol and dipentaerythritol in a mass ratio of 1:1.

[0040] In component B, the curing agent is polyamide, the curing accelerator is salicylic acid, the leveling agent is BYK-307, and the defoamer is BYK-054;

[0041] The carbon fiber of this invention has a diameter of 8-10 μm.

[0042] Preparation Example 1

[0043] The preparation method of the wear-resistant agent is as follows:

[0044] (1) Add silane coupling agent KH-560 to an aqueous ethanol solution with a volume fraction of 92% to prepare a mixed solution with a mass fraction of 0.7%. Adjust the pH to 4.5 and stir at room temperature for 35 min to allow KH-560 to be fully hydrolyzed. Add carbon fiber to the mixed solution at a ratio of 1 g: 110 mL and react at 55 °C for 6 h. After the reaction is complete, filter, wash, and dry to obtain carbon fiber modified with silane coupling agent.

[0045] (2) The carbon fiber modified with triethylamine and silane coupling agent, molybdenum sulfate and sodium thiosulfate are in a mass ratio of 1:12:12:6. The carbon fiber modified with silane coupling agent is added to a 6% molybdenum sulfate aqueous solution, and then triethylamine and sodium thiosulfate are added. The reaction is carried out at 85°C for 2 hours. After the reaction is completed, the mixture is filtered, washed and dried to obtain the wear-resistant agent.

[0046] Preparation Example 2

[0047] The preparation method of the wear-resistant agent is as follows:

[0048] (1) Add silane coupling agent KH-560 to a 95% ethanol aqueous solution to prepare a mixed solution with a mass fraction of 0.8%. Adjust the pH to 5 and stir at room temperature for 40 min to allow KH-560 to be fully hydrolyzed. Add carbon fiber to the mixed solution at a ratio of 1 g: 120 mL and react at 60 °C for 4 h. After the reaction is complete, filter, wash, and dry to obtain carbon fiber modified with silane coupling agent.

[0049] (2) The carbon fiber modified with triethylamine and silane coupling agent, molybdenum sulfate and sodium thiosulfate are in a mass ratio of 1:13:13:7. The carbon fiber modified with silane coupling agent is added to an aqueous solution of molybdenum sulfate with a mass fraction of 8%, and then triethylamine and sodium thiosulfate are added. The reaction is carried out at 90°C for 1 hour. After the reaction is completed, the mixture is filtered, washed and dried to obtain the wear-resistant agent.

[0050] Preparation Example 3

[0051] The preparation method of the wear-resistant agent is as follows:

[0052] (1) Add silane coupling agent KH-560 to a 90% volume fraction of ethanol aqueous solution to prepare a mixed solution with a mass fraction of 0.5%. Adjust the pH to 4 and stir at room temperature for 30 min to allow KH-560 to be fully hydrolyzed. Add carbon fiber to the mixed solution at a ratio of 1 g: 100 mL and react at 50 °C for 8 h. After the reaction is complete, filter, wash, and dry to obtain carbon fiber modified with silane coupling agent.

[0053] (2) The carbon fiber modified with triethylamine and silane coupling agent, molybdenum sulfate and sodium thiosulfate are in a mass ratio of 1:10:10:5. The carbon fiber modified with silane coupling agent is added to a 5% molybdenum sulfate aqueous solution, and then triethylamine and sodium thiosulfate are added. The reaction is carried out at 80°C for 3 hours. After the reaction is completed, the mixture is filtered, washed and dried to obtain the wear-resistant agent.

[0054] Preparation Example 4

[0055] The preparation process of modified bentonite is as follows:

[0056] L1: Bentonite was added to a 7% hydrochloric acid solution at a ratio of 1g:52mL. The solution was heated and refluxed for 2.5h to acidify the solution. The solution was then filtered, washed, and dried to obtain acidified bentonite.

[0057] L2: Add the epoxy silane coupling agent KH-560 to a 92% (v / v) aqueous ethanol solution to prepare a 0.7% (w / w) mixed solution. Adjust the pH to 4.5 and stir at room temperature for 35 min to allow KH-560 to be fully hydrolyzed. Add the acidified bentonite to the mixed solution at a ratio of 1 g: 110 mL and react at 70 °C for 8 h. After the reaction is complete, filter, wash, and dry to obtain the epoxy silane coupling agent modified bentonite.

[0058] L3: The ratio of bentonite modified with epoxy silane coupling agent to sulfuric acid solution is 1g:12mL. The bentonite modified with epoxy silane coupling agent is added to a 3% sulfuric acid solution and stirred at 65℃ for 18h. After the reaction is completed, the mixture is filtered, washed, and dried to obtain hydroxylated bentonite.

[0059] L4: Hydroxylated bentonite, 2,4,6-tricarboxylic acid-1,3,5-triazine, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, and pentaerythritol allyl ether were added in a mass ratio of 1:1:0.15:0.3:1.2. The hydroxylated bentonite was added to DMF (N,N-dimethylformamide), and under nitrogen protection, 2,4,6-tricarboxylic acid-1,3,5-triazine (CAS: 87145-66-2), EDC·HCl (1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride), and NHS (N-hydroxysuccinimide) were added. After stirring at 105°C for 4 h, pentaerythritol allyl ether was added, and stirring was continued for 13 h. The mixture was then distilled under reduced pressure, washed, and dried to obtain modified bentonite.

[0060] Preparation Example 5

[0061] The preparation process of modified bentonite is as follows:

[0062] L1: Bentonite and hydrochloric acid solution were added to an 8% hydrochloric acid solution at a ratio of 1g:55mL. The solution was heated and refluxed for 3 hours to acidify the solution. The solution was then filtered, washed, and dried to obtain acidified bentonite.

[0063] L2: Add the epoxy silane coupling agent KH-560 to a 95% (v / v) aqueous ethanol solution to prepare a 0.8% (w / w) mixed solution. Adjust the pH to 5 and stir at room temperature for 40 min to allow KH-560 to be fully hydrolyzed. Add the acidified bentonite to the mixed solution at a ratio of 1 g: 120 mL and react at 75 °C for 6 h. After the reaction is complete, filter, wash, and dry to obtain the epoxy silane coupling agent modified bentonite.

[0064] L3: The ratio of bentonite modified with epoxy silane coupling agent to sulfuric acid solution is 1g:15mL. The bentonite modified with epoxy silane coupling agent is added to a 4% sulfuric acid solution and stirred at 70℃ for 15h. After the reaction is completed, the mixture is filtered, washed, and dried to obtain hydroxylated bentonite.

[0065] L4: The hydroxylated bentonite, 2,4,6-tricarboxylic acid-1,3,5-triazine, EDC·HCl, NHS, and pentaerythritol allyl ether were mixed in a mass ratio of 1:1.4:0.2:0.4:1.5. The hydroxylated bentonite was added to DMF, and under nitrogen protection, 2,4,6-tricarboxylic acid-1,3,5-triazine, EDC·HCl, and NHS were added. The mixture was stirred at 110°C for 3 hours, and then pentaerythritol allyl ether was added. The mixture was stirred for another 15 hours, then distilled under reduced pressure, washed, and dried to obtain modified bentonite.

[0066] Preparation Example 6

[0067] The preparation process of modified bentonite is as follows:

[0068] L1: Bentonite and hydrochloric acid solution were added to a 6% hydrochloric acid solution at a ratio of 1g:50mL. The solution was heated and refluxed for 2 hours to acidify the solution. The solution was then filtered, washed, and dried to obtain acidified bentonite.

[0069] L2: Add the epoxy silane coupling agent KH-560 to a 90% (v / v) aqueous ethanol solution to prepare a 0.5% (w / w) mixed solution. Adjust the pH to 4 and stir at room temperature for 30 min to allow KH-560 to be fully hydrolyzed. Add the acidified bentonite to the mixed solution at a ratio of 1 g: 100 mL and react at 65 °C for 10 h. After the reaction is complete, filter, wash, and dry to obtain the epoxy silane coupling agent modified bentonite.

[0070] L3: The ratio of bentonite modified with epoxy silane coupling agent to sulfuric acid solution is 1g:10mL. The bentonite modified with epoxy silane coupling agent is added to a 2% sulfuric acid solution and stirred at 60℃ for 20h. After the reaction is completed, the mixture is filtered, washed, and dried to obtain hydroxylated bentonite.

[0071] L4: Hydroxylated bentonite, 2,4,6-tricarboxylic acid-1,3,5-triazine, EDC·HCl, NHS, and pentaerythritol allyl ether were added in a mass ratio of 1:0.9:0.1:0.2:0.8 to DMF. Under nitrogen protection, 2,4,6-tricarboxylic acid-1,3,5-triazine, EDC·HCl, and NHS were added. The mixture was stirred at 100°C for 5 hours, then pentaerythritol allyl ether was added, and stirring was continued for 12 hours. The mixture was then distilled under reduced pressure, washed, and dried to obtain modified bentonite.

[0072] Example 1

[0073] A flame-retardant modified bentonite composite coating is composed of component A and component B in a mass ratio of 1:0.5.

[0074] The above component A includes the following raw materials in parts by weight: 46 parts epoxy resin, 17 parts diluent, 2 parts wear-resistant agent of Preparation Example 1, and 8 parts charring agent;

[0075] The above-mentioned component B includes the following raw materials in parts by weight: 24 parts curing agent, 2 parts curing accelerator, 9 parts modified bentonite of Preparation Example 4, 0.4 parts leveling agent, and 0.3 parts defoamer.

[0076] The preparation method of the above-mentioned flame-retardant modified bentonite composite coating includes the following steps:

[0077] S1. Mix epoxy resin, abrasion resistant agent, charring agent and diluent evenly to obtain component A;

[0078] S2. Mix the curing agent, curing accelerator, modified bentonite, leveling agent and defoamer evenly to obtain component B;

[0079] S3. Mix component A and component B evenly.

[0080] Example 2

[0081] A flame-retardant modified bentonite composite coating is composed of component A and component B in a mass ratio of 1:0.7.

[0082] The above component A includes the following raw materials in parts by weight: 50 parts epoxy resin, 20 parts diluent, 3 parts wear-resistant agent of Preparation Example 2, and 10 parts charring agent;

[0083] The above-mentioned component B includes the following raw materials in parts by weight: 30 parts curing agent, 3 parts curing accelerator, 10 parts modified bentonite of Preparation Example 5, 0.5 parts leveling agent, and 0.5 parts defoamer.

[0084] The preparation method of the above flame-retardant modified bentonite composite coating is the same as that in Example 1.

[0085] Example 3

[0086] A flame-retardant modified bentonite composite coating is composed of component A and component B in a mass ratio of 1:0.3.

[0087] The above component A includes the following raw materials in parts by weight: 40 parts epoxy resin, 15 parts diluent, 1 part wear-resistant agent of Preparation Example 3, and 5 parts charring agent;

[0088] The above-mentioned component B includes the following raw materials in parts by weight: 20 parts curing agent, 1 part curing accelerator, 5 parts modified bentonite of Preparation Example 6, 0.3 parts leveling agent, and 0.1 parts defoamer.

[0089] The preparation method of the above flame-retardant modified bentonite composite coating is the same as that in Example 1.

[0090] Comparative Example 1

[0091] The difference between this comparative example and Example 1 is that a physical mixture of bentonite and 2,4,6-tricarboxylic acid-1,3,5-triazine is used in equal amounts to replace the modified bentonite in Preparation Example 4. The ratio of the two components remains the same as in Preparation Example 4.

[0092] Comparative Example 2

[0093] The difference between this comparative example and Example 1 is that a physical mixture of carbon fibers modified with a silane coupling agent and molybdenum disulfide is used to replace the wear-resistant agent in Preparation Example 1 in equal amounts. The preparation method of the carbon fibers modified with the silane coupling agent is the same as in Preparation Example 1, and the ratio of the amount of carbon fibers modified with the silane coupling agent to molybdenum disulfide is consistent with that in Preparation Example 1, the ratio of the amount of carbon fibers modified with the silane coupling agent to the amount of molybdenum sulfate in the molybdenum sulfate aqueous solution.

[0094] Experimental Example 1

[0095] The wear-resistant agent obtained in Preparation Example 1 and the modified bentonite obtained in Preparation Example 4 were characterized by scanning electron microscopy (SEM). The microstructure results are as follows: Figure 1-2 As shown.

[0096] Figure 1 SEM image of the wear-resistant agent obtained in Example 1. Figure 1 It can be seen that the wear-resistant agent maintains the complete carbon fiber skeleton structure, the surface roughness is significantly increased, and there is no obvious agglomeration phenomenon.

[0097] Figure 2 SEM image of the modified bentonite obtained in Example 4. Figure 2 It can be seen that the modified bentonite maintains a complete layered structure and its surface roughness is significantly increased.

[0098] Experimental Example 2

[0099] Impact resistance: Tested according to GB / T 1732-2020, the results are shown in Table 1;

[0100] Adhesion: The test was conducted in accordance with GB / T 9286-2021, and the results are shown in Table 1.

[0101] Flame retardant performance: Tested according to GB / T 2406.2-2009, the results are shown in Table 1;

[0102] Salt spray resistance: Tested according to GB / T 10125-2021 for 5500h, the results are shown in Table 1;

[0103] Alkali resistance: The test was conducted according to GB / T 9274-1988 (Method A). The test conditions were 25℃, 5% NaOH, and 800h. The results are shown in Table 1.

[0104] Acid resistance: The test was conducted according to GB / T 9274-1988 (Method A), with experimental conditions of 25℃, 5% H2SO4, and a time of 800h. The results are shown in Table 1.

[0105] Water resistance: The test was conducted according to Method A of GB / T 1733-1993, with a test temperature of 50℃ and a test time of 25 days. The results are shown in Table 1.

[0106] Abrasion resistance: Tested according to GB / T 1768-2006, the results are shown in Table 1.

[0107] Table 1

[0108]

[0109] As shown in Table 1, the coatings obtained in Examples 1-3 of this invention possess excellent mechanical properties, corrosion resistance, flame retardancy, and wear resistance.

[0110] Compared to Example 1, the mechanical properties, flame retardant properties, and corrosion resistance of Comparative Example 1 were all reduced. The experimental results indicate that simply mixing bentonite with 2,4,6-tricarboxylic acid-1,3,5-triazine through physical mixing cannot construct a chemically bonded synergistic intumescent flame-retardant system. The inert gas released by the thermal decomposition of the triazine ring and the char-forming effect of the pentaerythritol structure are difficult to synergistically exert, leading to a significant decrease in flame retardant performance. Simultaneously, the lack of chemical cross-linking between the allyl double bond and the epoxy resin matrix reduces the internal density of the coating film, shortens the penetration path of corrosive media, and, coupled with interfacial defects caused by uneven filler dispersion, significantly deteriorates the mechanical strength and long-term corrosion resistance of the coating. Therefore, grafting the triazine flame-retardant unit and pentaerythritol allyl ether onto the bentonite surface through chemical bonding is key to achieving a synergistic improvement in the flame retardant, corrosion-resistant, and mechanical properties of the coating.

[0111] Compared to Example 1, the wear resistance of Comparative Example 2 is reduced. The above experimental results show that the synergistic wear-resistant structure formed by in-situ loading of molybdenum disulfide onto carbon fibers is crucial for improving the wear resistance of the coating, and simple physical mixing cannot achieve the synergistic effect of long-term lubrication and load bearing.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. The basic principles and main features of the present invention have been described above with specific implementation schemes. Based on the present invention, some modifications or substitutions can be made, but these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of protection claimed by the present invention.

Claims

1. A flame-retardant modified bentonite composite coating, characterized in that, It is composed of component A and component B; the mass ratio of component A to component B is 1:(0.3-0.7). Component A comprises the following raw materials in parts by weight: 40-50 parts epoxy resin, 15-20 parts diluent, 1-3 parts abrasion resistant agent, and 5-10 parts charring agent. Component B comprises the following raw materials in parts by weight: 20-30 parts curing agent, 1-3 parts curing accelerator, 5-10 parts modified bentonite, 0.3-0.5 parts leveling agent, and 0.1-0.5 parts defoamer; The preparation process of the modified bentonite in component B is as follows: L1: Add bentonite modified with epoxy silane coupling agent to sulfuric acid solution, stir and react, then purify to obtain hydroxylated bentonite. L2: The hydroxylated bentonite was added to N,N-dimethylformamide. Under inert gas protection, 2,4,6-tricarboxylic acid-1,3,5-triazine, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and N-hydroxysuccinimide were added. After stirring, pentaerythritol allyl ether was added, and stirring was continued. The mixture was then purified to obtain the modified bentonite.

2. The flame-retardant modified bentonite composite coating according to claim 1, characterized in that, In step L1, the ratio of bentonite modified with epoxy silane coupling agent to sulfuric acid solution is 1g:(10-15)mL; the mass fraction of sulfuric acid solution is 2-4%; the stirring reaction temperature is 60-70℃ and the time is 15-20h.

3. The flame-retardant modified bentonite composite coating according to claim 2, characterized in that, The preparation process of the bentonite modified with the epoxy silane coupling agent is as follows: An epoxy-silane coupling agent was added to an aqueous ethanol solution, the pH was adjusted and the solution was stirred to obtain a mixed solution 1. An acidified bentonite was added to the mixed solution 1, and the solution was purified after reaction to obtain bentonite modified with the epoxy-silane coupling agent.

4. The flame-retardant modified bentonite composite coating according to claim 3, characterized in that, The ratio of acidified bentonite to mixed solution 1 is 1g:(100-120)mL; the epoxy silane coupling agent is KH-560; the volume fraction of the ethanol aqueous solution is 90-95%; the pH is adjusted to 4-5; the stirring time is 30-40min; the reaction temperature is 65-75℃ and the reaction time is 6-10h.

5. The flame-retardant modified bentonite composite coating according to claim 3, characterized in that, In step L2, the mass ratio of hydroxylated bentonite, 2,4,6-tricarboxylic acid-1,3,5-triazine, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, and pentaerythritol allyl ether is 1:(0.9-1.4):(0.1-0.2):(0.2-0.4):(0.8-1.5); the stirring temperature is 100-110℃, and the stirring time is 3-5 hours; the stirring continues for 12-15 hours.

6. The flame-retardant modified bentonite composite coating according to claim 1, characterized in that, The preparation process of the wear-resistant agent in component A is as follows: The carbon fibers modified with silane coupling agent were added to an aqueous solution of molybdenum sulfate, followed by the addition of triethylamine and sodium thiosulfate. After heating and reaction, the mixture was purified to obtain the wear-resistant agent.

7. The flame-retardant modified bentonite composite coating according to claim 6, characterized in that, The mass ratio of molybdenum sulfate to sodium thiosulfate in the triethylamine- and silane coupling agent-modified carbon fiber and the molybdenum sulfate aqueous solution is 1:(10-13):(10-13):(5-7); the mass fraction of the molybdenum sulfate aqueous solution is 5-8%; the heating reaction temperature is 80-90℃ and the time is 1-3h.

8. The flame-retardant modified bentonite composite coating according to claim 7, characterized in that, The preparation process of the silane coupling agent modified carbon fiber is as follows: A silane coupling agent was added to an aqueous ethanol solution, the pH was adjusted to 4-5, and the mixture was stirred to obtain a mixed solution 2. Carbon fibers were added to the mixed solution 2, and the mixture was reacted at 50-60℃ for 4-8 hours. After purification, the carbon fibers modified with the silane coupling agent were obtained.

9. The flame-retardant modified bentonite composite coating according to claim 1, characterized in that, The diluent in component A is phenyl glycidyl ether or 1,4-butanediol diglycidyl ether, and the charring agent is composed of pentaerythritol and dipentaerythritol in a mass ratio of 1:1; the curing agent in component B is polyamide or polyethyleneimine, the curing accelerator is salicylic acid or phenol, the leveling agent is BYK-307, and the defoamer is BYK-054.

10. A method for preparing the flame-retardant modified bentonite composite coating according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Mix epoxy resin, abrasion resistant agent, charring agent and diluent evenly to obtain component A; S2. Mix the curing agent, curing accelerator, modified bentonite, leveling agent and defoamer evenly to obtain component B; S3. Mix component A and component B evenly.

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