Functional filler, method for preparing the same, fireproof and heat-insulating coating and application thereof

Abstract

The application provides a functional filler and a preparation method thereof, a fireproof and heat-insulating coating and application, and belongs to the technical field of coatings. The preparation method of the heat-insulating functional filler with a core-shell structure comprises the following steps: adopting a sol-gel method and a high-temperature sintering technology, and coating cerium dioxide and titanium dioxide in silica to form a core-shell structure; and the core-shell structure is composed of a fully-coated core-shell structure and a semi-coated core-shell structure. The silica has a hollow core-shell structure, and the cerium dioxide and the titanium dioxide are filled in the shell of the silica core-shell structure. The fireproof and heat-insulating functional filler with the core-shell structure prepared by adopting the sol-gel method and the high-temperature sintering technology is compounded with an intumescent flame retardant to prepare a fireproof and heat-insulating coating, and the coating has excellent fire resistance, heat insulation and fireproof performance; the fireproof and heat-insulating coating is sprayed on the surface of carbon steel to form a coating, and when the thickness of the coating is 10mm, the coating can resist the ablation of acetylene flame for 60min, and the back temperature of the carbon steel is less than or equal to 280 DEG C.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically relating to a functional filler and its preparation method, a fireproof and heat-insulating coating, and its application. Background Technology

[0002] Steel structures are excellent conductors of heat. During a fire, as the temperature of a steel structure rises, its load-bearing capacity and structural strength decrease sharply, potentially leading to building collapse and causing serious casualties and property damage. Applying fire-retardant coatings to steel structures is the most convenient and effective measure for fire protection. Existing fire-retardant coatings generally have excellent fire-retardant effects, but their other properties, such as heat insulation, salt spray resistance, and resistance to artificial aging, are relatively poor, thus affecting their service life and protective effect. Therefore, developing a special coating that combines heat insulation and fire resistance properties for application to the surface of steel structures is particularly important.

[0003] Silica, commonly known as white carbon black, is a white, non-toxic, amorphous, fine powder. It is an important inorganic silicon compound with excellent properties such as porosity, high dispersibility, light weight, good chemical stability, high temperature resistance, non-combustibility, and good electrical insulation. Titanium dioxide (TiO2) in fire-retardant coatings has multiple functions including heat insulation, flame retardancy, smoke suppression, and weather resistance. TiO2 has a low thermal conductivity of approximately 8.4 W / m·K, which can be reduced to 0.5~2 W / m·K through porous structure design, thus slowing down heat transfer. Titanium dioxide can also shield ultraviolet radiation, prevent resin matrix degradation, and effectively reflect radiant heat in a fire. Furthermore, it can catalyze the pyrolysis of polymer base materials (such as epoxy resin) at high temperatures to form a dense carbon layer, inhibiting the release of combustible gases. Existing technologies that combine titanium dioxide and silicon dioxide to form core-shell structures mostly involve coating the silicon dioxide surface with titanium dioxide to fully utilize the optical properties of titanium dioxide. For example, Chinese invention patent CN 108570248A discloses a method for preparing a core-shell titanium dioxide-coated silicon dioxide material, resulting in a functional material that can be used in coatings, inks, etc. This material uses silicon dioxide as the core and titanium dioxide as the shell, possessing reinforcing, thickening, and thixotropic properties. The coating effect of titanium dioxide alters the surface optical properties of silicon dioxide, making it a substitute for titanium dioxide. However, this core-shell structure formed by titanium dioxide-coated silicon dioxide cannot fully utilize the properties of silicon dioxide.

[0004] Cerium dioxide is a rare earth oxide with high-temperature stability (melting point 2400℃), antioxidant properties, and catalytic performance. When compounded with ammonium polyphosphate, cerium dioxide can stabilize the expanded carbon layer structure and improve the fire resistance limit. To fully utilize the role of cerium dioxide, it is usually coated on the surface of silicon dioxide to form a core-shell structure. Chinese invention patent CN108022758A discloses a carbon-coated cerium dioxide hollow sphere. Cerium dioxide-coated silicon dioxide microspheres are prepared using silicon dioxide as a template, and then a carbon layer is coated on the cerium dioxide-coated silicon dioxide microspheres and sintered. Then, an etchant is used to remove the silicon dioxide to obtain carbon-coated cerium dioxide hollow spheres. This preparation method can obtain hollow spheres that are almost fully carbon-coated. However, compared with particle physical mixing, the thermal insulation performance of the fully coated cerium dioxide structure is improved, but the fire resistance performance is reduced.

[0005] Based on the problems existing in the prior art, the present invention provides a fireproof and heat-insulating coating that can ensure that titanium dioxide and cerium dioxide can be retained in the matrix material even after long-term use, thereby solving the technical problems existing in the prior art. Summary of the Invention

[0006] The purpose of this invention is to provide a functional filler and its preparation method, a fireproof and heat-insulating coating and its application, so as to improve the performance of the coating and enhance the protective effect of the coating.

[0007] As one of the objectives of this invention, a method for preparing a functional filler is provided, specifically including using a sol-gel method and high-temperature sintering technology to coat cerium dioxide and titanium dioxide inside silicon dioxide to form a core-shell structure; wherein the core-shell structure consists of a fully coated core-shell structure and a partially coated core-shell structure; in the fully coated core-shell structure, the silicon dioxide has a hollow structure, and cerium dioxide and titanium dioxide particles fill the interior of the hollow structure; in the partially coated core-shell structure, the cerium dioxide and titanium dioxide particles are partially exposed on the exterior of the core-shell structure.

[0008] Preferably, the proportion of the fully enclosed core-shell structure is 70-80%.

[0009] As a preferred embodiment, the preparation method of the functional filler specifically includes: dispersing cerium dioxide and titanium dioxide in a hydrogen peroxide aqueous solution for surface hydroxylation; then, adding a small molecule silane solution to react and form a sol, in which cerium dioxide and titanium dioxide are encapsulated; then adding a complexing agent and a stabilizer; heating in a water bath to form a transparent gel; and finally, sintering the gel at high temperature under a nitrogen atmosphere to obtain the functional filler.

[0010] In a preferred embodiment, the small molecule silane solution is obtained by hydrolyzing methyltrimethoxysilane, methyltriethoxysilane, and isobutyltrimethoxysilane in an acidic solution.

[0011] In a preferred embodiment, the functional filler contains cerium dioxide, titanium dioxide and silicon dioxide, and the molar ratio of cerium dioxide:titanium dioxide:silicon dioxide is (1~2):(1~2):(1~50).

[0012] As a preferred embodiment, the concentration of the hydrogen peroxide solution is 25-40 wt%.

[0013] In a preferred embodiment, the hydroxylation includes: adding cerium dioxide and titanium dioxide to a hydrogen peroxide aqueous solution, adding an acidic solution to adjust the solution to pH ~3.0, stirring slowly under ultraviolet light for 5 ~ 10 h, and using the hydroxyl radicals ·OH generated by the decomposition of hydrogen peroxide to adsorb onto the surface of cerium dioxide and titanium dioxide, thereby hydroxylating the surface of cerium dioxide and titanium dioxide.

[0014] In a preferred embodiment, the complexing agent is citric acid, used to adjust the pH of the solution to approximately 5.0.

[0015] In a preferred embodiment, the stabilizer is polyvinylpyrrolidone.

[0016] In a preferred embodiment, the mass ratio of the complexing agent to the stabilizer is 10~15:1.

[0017] In a preferred embodiment, the water bath heating temperature is 40~50℃.

[0018] In a preferred embodiment, the high-temperature sintering includes reacting under a nitrogen atmosphere at a heating rate of 5°C / min to a temperature of 400-500°C, holding at that temperature for 5-10 hours, and then annealing to obtain the functional filler.

[0019] As a second objective of the invention, the present invention also provides a functional filler prepared by the preparation method described above.

[0020] As a third objective of the invention, the present invention also provides a fire-retardant and heat-insulating coating, comprising at least the functional fillers described above.

[0021] In a preferred embodiment, the fireproof and heat-insulating coating includes the core-shell heat-insulating filler, an intumescent flame retardant, an organic solvent, additives, an epoxy resin, and an epoxy curing agent.

[0022] In a preferred embodiment, the additives include one or a combination of the anti-settling agent bentonite and high-temperature resistant carbon fiber.

[0023] Preferably, the length of the high-temperature resistant carbon fiber is 4~10mm.

[0024] In a preferred embodiment, the epoxy resin is one or a combination of pure epoxy resin, silicone-modified epoxy resin, and acrylic-modified epoxy resin.

[0025] Preferably, the epoxy resin has a solid content of 75-100%.

[0026] In a preferred embodiment, the organic solvent is the reactive diluent AGE.

[0027] In a preferred embodiment, the epoxy curing agent is one or a combination of polyamide curing agent, phenolic amine curing agent, and alicyclic amine curing agent.

[0028] Preferably, the mass ratio of the functional filler to the epoxy resin is 1~2:10.

[0029] Preferably, the mass ratio of the functional filler to the intumescent flame retardant is 1~2:5.

[0030] In a preferred embodiment, the fireproof and heat-insulating coating comprises, by weight: 40-50 parts epoxy resin, 5-10 parts core-shell structure heat-insulating filler, 25-50 parts intumescent flame retardant, 10-20 parts organic solvent, 0.5-2.0 parts additives, and 30-40 parts epoxy curing agent.

[0031] As a fourth objective of the invention, the present invention also provides a method for preparing the coating as described above, comprising the following specific steps:

[0032] S1. Dissolve the epoxy resin in an organic solvent and stir until homogeneous to obtain mixture A;

[0033] S2. Add the additive to the mixture A, stir until homogeneous, and obtain mixture B;

[0034] S3. Add the core-shell structure heat insulation filler and the intumescent flame retardant to the mixture B, stir at high speed, then add the epoxy curing agent and stir evenly to obtain the fireproof and heat insulation coating.

[0035] As a fifth objective of the invention, the present invention also provides a fireproof and heat-insulating coating, comprising spraying the fireproof and heat-insulating coating as described above onto the surface of a metal or carbon steel substrate, and curing it to form a paint film, thereby obtaining the fireproof and heat-insulating coating.

[0036] Preferably, the thickness of the fireproof and heat-insulating coating is 5-10 mm.

[0037] Preferably, the pull-out adhesion is 5~6MPa; the thermal conductivity is ≤0.09W / (m·K); and the fire resistance limit is 2.5h.

[0038] More preferably, the thermal conductivity is 0.04~0.07 W / (m·K).

[0039] Based on the above analysis, this invention uses a sol-gel method and high-temperature sintering technology to prepare a fire-resistant and heat-insulating functional filler with a core-shell structure. Cerium dioxide-titanium dioxide is encapsulated in silica with a hollow structure, and then compounded with an intumescent flame retardant to prepare a fire-resistant and heat-insulating coating. The coating has a fire resistance limit ≥2.5h, a thermal conductivity ≤0.09W / (m·K), a pull-out adhesion of 5~6MPa, and a fire rating of A1. When the fire-resistant and heat-insulating coating is sprayed onto the surface of carbon steel to form a coating, when the coating thickness is 10mm, it is resistant to acetylene flame ablation for 60min, and the back temperature of the carbon steel is ≤280℃.

[0040] As a sixth objective of the invention, the present invention also provides a fire-retardant and heat-insulating coating as described above, or the application of a fire-retardant and heat-insulating coating as described above on the surface of materials such as steel structures and aluminum alloys.

[0041] The beneficial technical effects obtained by this invention are as follows:

[0042] 1. The technical solution of this invention encapsulates cerium dioxide-titanium dioxide in silicon dioxide with a hollow structure to form a core-shell structure. This core-shell structure can reduce the thermal conductivity of the fire-retardant coating, thereby improving the heat insulation function of the coating.

[0043] 2. This invention utilizes silicon dioxide with a hollow structure formed by high-temperature sintering, which contains a large amount of air, significantly reducing the heat transfer process of the fireproof coating. On the other hand, the silanol groups on the surface of the silicon dioxide obtained by high-temperature sintering form hydrogen bonds with pentaerythritol, enhancing the compatibility between silicon dioxide and the components of the coating. Under high-temperature conditions, pentaerythritol, melamine, and ammonium polyphosphate are used in combination to form a synergistic effect. The hydroxyl groups of pentaerythritol can react with phosphate esters to generate pentaerythritol bisphosphate melamine salt, which further decomposes to produce volatiles such as NH3 and H2O, carrying away heat and promoting coating expansion to form a more stable heat insulation layer.

[0044] 3. This invention uses cerium dioxide-titanium dioxide@silicon dioxide with a core-shell structure as a heat-insulating filler added to epoxy resin to prepare a fire-retardant and heat-insulating coating. Simultaneously, the exposed and dispersed cerium dioxide, which is not fully coated, can stabilize the expanded char layer structure and improve the fire resistance limit. Titanium dioxide in the fire-retardant coating has multiple functions, including heat insulation, flame retardancy, smoke suppression, and weather resistance. The core-shell structured heat-insulating filler can significantly reduce the transfer of heat generated during combustion to the steel structure substrate, avoiding the problem of reduced strength of the steel structure at high temperatures.

[0045] 4. The fireproof and heat-insulating coating prepared using the present invention uses an active diluent as a solvent, and there is no VOC emission during the curing process, making it environmentally friendly and pollution-free. Attached Figure Description

[0046] Figure 1 The image shows a scanning electron microscope (SEM) image of cerium dioxide-titanium dioxide@silicon dioxide prepared in Example 1 of this invention.

[0047] Figure 2 The images show the fireproof and heat-insulating coating prepared in Example 1 of this invention, applied to the surface of a steel structure, before, during, and after acetylene flame ablation.

[0048] Figure 3 The figure shows the temperature change curves of the fireproof and heat-insulating coating of Embodiment 1 of the present invention on the fire-facing side of the coating and the back side of the carbon steel substrate during the acetylene flame ablation process. The thickness of the fireproof and heat-insulating coating is 7 mm. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] This invention provides a heat-insulating filler composed of a fully encapsulated core-shell structure and a semi-encapsulated core-shell structure of cerium dioxide-titanium dioxide@silicon dioxide.

[0051] In the fully enclosed core-shell structure, silicon dioxide has a hollow structure, and cerium dioxide and titanium dioxide particles fill the interior of the hollow structure; in the semi-enclosed core-shell structure, cerium dioxide and titanium dioxide particles are partially exposed outside the core-shell structure, and at the same time, during the calcination process, the cerium dioxide and titanium dioxide particles in the semi-enclosed core-shell structure are released from the shell layer and dispersed outside the core-shell structure.

[0052] In some specific embodiments, the method for preparing the heat-insulating filler includes:

[0053] This includes using sol-gel method and high-temperature sintering technology to coat cerium dioxide and titanium dioxide inside silicon dioxide, forming a fully coated core-shell structure and a semi-coated core-shell structure; wherein, in the fully coated core-shell structure, silicon dioxide has a hollow structure, and cerium dioxide and titanium dioxide particles fill the interior of the hollow structure; in the semi-coated core-shell structure, cerium dioxide and titanium dioxide particles are partially exposed on the outside of the core-shell structure.

[0054] Furthermore, the fully enclosed core-shell structure accounts for 70-80% of the thermal insulation filler.

[0055] In some specific embodiments, the coating steps include: using cerium dioxide and titanium dioxide as raw materials, dispersing them in a concentrated hydrogen peroxide aqueous solution for surface hydroxylation, adding a small molecule silane solution for reaction, then adding a complexing agent and a stabilizer, heating in a water bath to form a transparent gel, and finally sintering the gel at high temperature under a nitrogen atmosphere.

[0056] In some specific embodiments, the small molecule silane solution is obtained by hydrolyzing methyltrimethoxysilane, methyltriethoxysilane, and isobutyltrimethoxysilane in acetic acid solution.

[0057] In some specific embodiments, the molar ratio of cerium dioxide:titanium dioxide:silicon dioxide in the cerium dioxide-titanium dioxide@silicon dioxide powder is (1~2):(1~2):(1~50).

[0058] In some specific embodiments, the hydroxylation involves adding cerium dioxide and titanium dioxide to a 30wt% hydrogen peroxide aqueous solution, adding a small amount of acetic acid to adjust the pH of the solution to around 3.0, and slowly stirring under ultraviolet light for 5-10 hours. The hydroxyl radicals (·OH) generated by the decomposition of hydrogen peroxide are adsorbed onto the surface of cerium dioxide and titanium dioxide, thereby hydroxylating their surfaces.

[0059] In some specific embodiments, the complexing agent is citric acid, and the stabilizer is polyvinylpyrrolidone. The mass ratio of the complexing agent to the stabilizer is 10-15:1.

[0060] In some specific embodiments, the high-temperature sintering includes sintering for 5 to 10 hours under nitrogen gas, a heating rate of 5°C / min, and a temperature of 400 to 500°C, followed by annealing to obtain the cerium dioxide-titanium dioxide@silicon dioxide.

[0061] In some specific embodiments, the water bath heating temperature is 40~50℃.

[0062] In some specific embodiments, the preparation method of the fireproof and heat-insulating coating includes at least the core-shell heat-insulating filler, intumescent flame retardant, organic solvent, additives, epoxy resin and epoxy curing agent.

[0063] In some specific embodiments, the intumescent flame retardant includes a compound of ammonium polyphosphate (APP), pentaerythritol (PER), and melamine (MEL).

[0064] In some specific embodiments, the mass ratio of ammonium polyphosphate: pentaerythritol: melamine is 3:1:1.

[0065] In some specific embodiments, the additives include one or a combination of the anti-settling agent bentonite and high-temperature resistant carbon fiber.

[0066] In some specific embodiments, the mass ratio of the core-shell structure thermal insulation filler to the organic resin is 1~2:10.

[0067] In some specific embodiments, the mass ratio of the core-shell structure thermal insulation filler to the intumescent flame retardant is 1~2:5.

[0068] In some specific embodiments, the epoxy resin is one or a combination of pure epoxy resin, silicone-modified epoxy resin, and acrylic-modified epoxy resin, and the solid content of the epoxy resin is 75% to 100%.

[0069] In some specific embodiments, the organic solvent is the reactive diluent AGE.

[0070] In some specific embodiments, the epoxy curing agent is one or a combination of polyamide curing agent, phenolic amine curing agent, and alicyclic amine curing agent.

[0071] In some specific embodiments, the fireproof and heat-insulating coating comprises, by weight: 40-50 parts epoxy resin, 5-10 parts core-shell structure heat-insulating filler, 25-50 parts intumescent flame retardant, 10-20 parts organic solvent, 0.5-2.0 parts additives, and 30-40 parts epoxy curing agent.

[0072] In some specific embodiments, the preparation method of the fire-retardant and heat-insulating coating includes the following specific steps:

[0073] S1. Dissolve the epoxy resin in an organic solvent and stir until homogeneous to obtain mixture A;

[0074] S2. Add the additive to the mixture A, stir until homogeneous, and obtain mixture B;

[0075] S3. Add the core-shell structure heat insulation filler and the intumescent flame retardant to the mixture B, stir at high speed, then add the epoxy curing agent and stir evenly to obtain the fireproof and heat insulation coating.

[0076] In some specific embodiments, fire-retardant and heat-insulating coatings are sprayed onto the surface of the steel structure, and after curing, a paint film is formed to obtain a fire-retardant and heat-insulating coating.

[0077] In some specific embodiments, the thickness of the fireproof and heat-insulating coating is 5-10 mm.

[0078] In some specific embodiments, the fire resistance limit time is ≥2.5h, the thermal conductivity is ≤0.09W / (m·K), and the fire rating is A1.

[0079] In some specific embodiments, the fireproof and heat-insulating coating is applied to the surface of carbon steel. When the coating thickness is 10 mm, the back temperature of the carbon steel is ≤280℃ after 60 minutes of acetylene flame erosion.

[0080] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.

[0081] Unless otherwise specified in the embodiments, the techniques or conditions described in the literature in this field or in accordance with the product manual may be followed.

[0082] Example 1

[0083] This embodiment provides a method for preparing a fireproof and heat-insulating coating, the specific steps of which include:

[0084] 1. Preparation of core-shell structured thermal insulation fillers

[0085] First, weigh 1 mol of titanium dioxide and 1 mol of cerium dioxide and add them to 500 g of 30 wt% hydrogen peroxide solution. Add 5 drops of 5 wt% acetic acid to adjust the pH of the solution to 3.0. Stir slowly for 10 h under ultraviolet light irradiation. The hydroxyl radicals (·OH) generated by the decomposition of hydrogen peroxide are adsorbed on the surface of cerium dioxide and titanium dioxide, causing them to be hydroxylated. Then, wash with 500 mL of deionized water 5 times and centrifuge to obtain reactant A.

[0086] Then, 1000g of methyltrimethoxysilane was weighed and added to 100g of 0.1mol / L acetic acid solution, and stirred at 200r / min for 2h to obtain silane hydrolysate B.

[0087] Finally, reactant A was added to hydrolysate B, along with 12g of citric acid complexing agent and 1.0g of polyvinylpyrrolidone stabilizer to improve the stability of the sol. The mixture was stirred in a 50℃ water bath for 5 hours to form a transparent sol, which was then allowed to stand at room temperature to 25℃ for 24 hours to allow further polymerization and the formation of a stable colloid. The gel was then calcined in a nitrogen atmosphere at a heating rate of 5℃ / min to 500℃ for 5 hours. The final product obtained was cerium dioxide-titanium dioxide@silicon dioxide with a core-shell structure.

[0088] The cerium dioxide-titanium dioxide@silicon dioxide powder prepared by the above method was analyzed by scanning electron microscopy (SEM). See the attached SEM images for details. Figure 1As shown in the figure, the cerium dioxide-titanium dioxide@silica powder has a partially hollow structure containing a large amount of air. Since air has a lower thermal conductivity (approximately 0.027 W / mk), it can significantly reduce the heat transfer process of the fire-retardant coating. In addition to the fully encapsulated structure, the cerium dioxide-titanium dioxide@silica powder also has a partially semi-encapsulated structure. Within the partially encapsulated shell, the cerium dioxide and titanium dioxide particles are dispersed outside the core-shell structure and are in a homogeneous dispersion state. The exposed cerium dioxide and titanium dioxide particles have a diameter of 1-2 micrometers. The volume of the fully encapsulated core-shell structure accounts for 70-80% of the total powder volume.

[0089] Cerium dioxide-titanium dioxide@silicon dioxide powder was added as a functional filler to fireproof and heat-insulating coatings.

[0090] 2. Preparation of fire-retardant and heat-insulating coatings

[0091] (1) Dissolve 40g of epoxy resin E51 (purchased from Nan Ya Epoxy Resin (Kunshan) Co., Ltd., with a solid content of 100%) in 10g of reactive diluent AGE (purchased from Hubei Green Home Material Technology Co., Ltd., with an epoxy value of 0.32) and stir until homogeneous. Then add 30g of intumescent flame retardant (containing 18g of ammonium polyphosphate, 6g of pentaerythritol and 6g of melamine) to obtain mixture A.

[0092] (2) Add 0.5g of bentonite anti-settling agent and 1.5g of high-temperature resistant carbon fiber (fiber length of 6mm) to the mixture A, stir evenly to obtain mixture B;

[0093] (3) Add 10g of cerium dioxide-titanium dioxide@silicon dioxide to the mixture B, stir evenly, and finally add 30g of polyamide epoxy curing agent (purchased from Dongguan Zhenhe Resin Technology Co., Ltd., with a solid content of 80%), stir evenly, and the fireproof and heat-insulating coating is obtained.

[0094] Performance characterization:

[0095] The coating prepared in Example 1 was brushed onto a carbon steel plate and cured at room temperature (25°C) for 24 hours. The thickness of the fireproof and heat-insulating coating film was controlled to be 7 mm, thus obtaining the coating test plate. (See [link to relevant documentation]). Figure 2 An acetylene flame was used to conduct an ablation test on the coated test plate. Simultaneously, the temperature changes on the fire-facing side of the carbon steel sample coating and the back surface of the carbon steel were measured. The temperature change curves are shown in [Figure number missing]. Figure 3 .exist Figure 3 In the experiment, the temperature of the fire-facing surface of the carbon steel sample coating was ~910℃, and the back temperature of the carbon steel remained at ~280℃ for 180 minutes. This demonstrates that after the carbon steel sample was coated with the fire-retardant coating of Example 1, the fire-retardant coating provided good heat insulation and fire protection for the carbon steel substrate during acetylene combustion.

[0096] The results of the pull-out adhesion, thermal conductivity, fire resistance limit, salt spray resistance and aging resistance tests of the coating prepared in this embodiment are shown in Table 1.

[0097] Example 2

[0098] The preparation method of the fireproof and heat-insulating coating provided in this embodiment is basically the same as that in Example 1, except that the amount of cerium dioxide-titanium dioxide@silicon dioxide powder added is different.

[0099] Specifically, the preparation methods of fire-retardant and heat-insulating coatings include:

[0100] (1) Dissolve 40g of epoxy resin E51 (purchased from Nan Ya Epoxy Resin (Kunshan) Co., Ltd., with a solid content of 100%) in 10g of reactive diluent AGE (purchased from Hubei Green Home Material Technology Co., Ltd., with an epoxy value of 0.32) and stir evenly. Then add 30g of intumescent flame retardant (containing 18g of ammonium polyphosphate, 6g of pentaerythritol and 6g of melamine) to obtain mixture A;

[0101] (2) Add 0.5g of bentonite anti-settling agent and 1.5g of high-temperature resistant carbon fiber (fiber length of 6mm) to the mixture A, stir evenly to obtain mixture B;

[0102] (3) Add 5g of cerium dioxide-titanium dioxide@silicon dioxide to the mixture B, stir evenly, and finally add 30g of polyamide epoxy curing agent (purchased from Dongguan Zhenhe Resin Technology Co., Ltd., with a solid content of 80%), stir evenly, and the fireproof and heat-insulating coating is obtained.

[0103] The results of the pull-out adhesion, thermal conductivity, fire resistance limit, salt spray resistance and aging resistance tests of the coating prepared in this embodiment are shown in Table 1.

[0104] Example 3

[0105] The preparation method of the fireproof and heat-insulating coating provided in this embodiment is basically the same as that in Example 1, except that the amount of cerium dioxide and titanium dioxide added is different in the preparation method of the heat-insulating functional filler with a core-shell structure. Specifically, the preparation method of the heat-insulating functional filler includes:

[0106] First, weigh 1 mol of titanium dioxide and 2 mol of cerium dioxide and add them to 500 g of 30 wt% hydrogen peroxide solution. Add 5 drops of 5 wt% acetic acid to adjust the pH of the solution to 3.0. Stir slowly for 10 h under ultraviolet light irradiation. The hydroxyl radicals (·OH) generated by the decomposition of hydrogen peroxide are adsorbed on the surface of cerium dioxide and titanium dioxide, causing them to be hydroxylated. Then, wash with 500 mL of deionized water 5 times and centrifuge to obtain reactant A.

[0107] Then, 1000g of methyltrimethoxysilane was weighed and added to 100g of 0.1mol / L acetic acid solution, and stirred at 200r / min for 2h to obtain silane hydrolysate B.

[0108] Finally, reactant A was added to hydrolysate B, along with 12g of citric acid complexing agent and 1.0g of polyvinylpyrrolidone stabilizer to improve the stability of the sol. The mixture was stirred in a 50°C water bath for 5 hours to form a transparent sol, which was then allowed to stand at room temperature to 25°C for 24 hours to further polymerize and form a stable colloid. The gel was then calcined at 500°C for 4 hours under a nitrogen atmosphere to obtain a cerium dioxide-titanium dioxide@silicon dioxide product with a core-shell structure. The subsequent preparation process for the fire-retardant coating was the same as in Example 1.

[0109] The results of the pull-out adhesion, thermal conductivity, fire resistance limit, salt spray resistance and aging resistance tests of the coating prepared in Example 3 are shown in Table 1.

[0110] Example 4

[0111] The preparation method of the fireproof and heat-insulating coating provided in this embodiment is basically the same as that in Example 1, except that the amount of cerium dioxide and titanium dioxide added is different in the preparation method of the heat-insulating functional filler with a core-shell structure. Specifically, the preparation method of the heat-insulating functional filler includes:

[0112] First, weigh 1 mol of titanium dioxide and 1 mol of cerium dioxide and add them to 500 g of 30 wt% hydrogen peroxide solution. Add 5 drops of 5 wt% acetic acid to adjust the pH of the solution to 3.0. Stir slowly for 10 h under ultraviolet light irradiation. The hydroxyl radicals (·OH) generated by the decomposition of hydrogen peroxide are adsorbed on the surface of cerium dioxide and titanium dioxide, causing them to be hydroxylated. Then, wash with 500 mL of deionized water 5 times and centrifuge to obtain reactant A.

[0113] Then, 1360g of methyltrimethoxysilane was weighed and added to 100g of 0.1mol / L acetic acid solution, and stirred at 200r / min for 2h to obtain silane hydrolysate B.

[0114] Finally, reactant A was added to hydrolysate B, along with 12g of citric acid complexing agent and 1.0g of polyvinylpyrrolidone stabilizer to improve the stability of the sol. The mixture was stirred in a 50℃ water bath for 5 hours to form a transparent sol, which was then allowed to stand at room temperature to 25℃ for 24 hours to allow further polymerization and the formation of a stable colloid. The gel was then calcined at 500℃ for 4 hours under a nitrogen atmosphere to obtain a cerium dioxide-titanium dioxide@silicon dioxide product with a core-shell structure.

[0115] The results of the pull-out adhesion, thermal conductivity, fire resistance limit, salt spray resistance and aging resistance tests of the coating prepared in this embodiment are shown in Table 1.

[0116] Example 5

[0117] The preparation method of the fireproof and heat-insulating coating provided in this embodiment is basically the same as that in Example 1, except that the amount of methyltrimethoxysilane added is different in the preparation method of the heat-insulating functional filler with a core-shell structure. Specifically, the preparation method of the heat-insulating functional filler includes:

[0118] First, weigh 1 mol of titanium dioxide and 1 mol of cerium dioxide and add them to 500 g of 30 wt% hydrogen peroxide solution. Add 5 drops of 5 wt% acetic acid to adjust the pH of the solution to 3.0. Stir slowly for 10 h under ultraviolet light irradiation. The hydroxyl radicals (·OH) generated by the decomposition of hydrogen peroxide are adsorbed on the surface of cerium dioxide and titanium dioxide, causing them to be hydroxylated. Then, wash with 500 mL of deionized water 5 times and centrifuge to obtain reactant A.

[0119] Then, 2720g of methyltrimethoxysilane was weighed and added to 100g of 0.1mol / L acetic acid solution, and stirred at 200r / min for 2h to obtain silane hydrolysate B.

[0120] Finally, reactant A was added to hydrolysate B, along with 12g of citric acid complexing agent and 1.0g of polyvinylpyrrolidone stabilizer to improve the stability of the sol. The mixture was stirred in a 50℃ water bath for 5 hours to form a transparent sol, which was then allowed to stand at room temperature to 25℃ for 24 hours to further polymerize and form a stable colloid. The gel was then calcined at 500℃ for 5 hours under a nitrogen atmosphere at a heating rate of 5℃ / min. The final product obtained was cerium dioxide-titanium dioxide@silicon dioxide with a core-shell structure.

[0121] The results of the pull-out adhesion, thermal conductivity, fire resistance limit, salt spray resistance and aging resistance tests of the coating prepared in this embodiment are shown in Table 1.

[0122] Comparative Example 1

[0123] This comparative example provides a method for preparing a fireproof and heat-insulating coating, which is basically the same as the preparation method in Example 1. The only difference is that titanium dioxide is not added in the step of preparing the core-shell structure heat-insulating filler. All other steps are the same.

[0124] The results of the pull-out adhesion, thermal conductivity, fire resistance limit, salt spray resistance and aging resistance tests of the fireproof and heat-insulating coating prepared in this comparative example are shown in Table 1.

[0125] Comparative Example 2

[0126] This comparative example provides a method for preparing a fireproof and heat-insulating coating, which is basically the same as the preparation method in Example 1. The only difference is that cerium dioxide and titanium dioxide are not added in the step of preparing the core-shell structure heat-insulating filler. All other steps are the same.

[0127] The results of the pull-out adhesion, thermal conductivity, fire resistance limit, salt spray resistance and aging resistance tests of the fireproof and heat-insulating coating prepared in this comparative example are shown in Table 1.

[0128] Comparative Example 3

[0129] This comparative example provides a method for preparing a fireproof and heat-insulating coating, which is basically the same as the preparation method in Example 1, except that the 10g of cerium dioxide-titanium dioxide@silicon dioxide added is replaced with 10g of silicon dioxide powder, and all other steps are the same.

[0130] The results of the pull-out adhesion, thermal conductivity, fire resistance limit, salt spray resistance and aging resistance tests of the fireproof and heat-insulating coating prepared in this comparative example are shown in Table 1.

[0131] Comparative Example 4

[0132] This comparative example provides a method for preparing a fire-retardant and heat-insulating coating, which is basically the same as the preparation method in Example 1, except that the 10g of cerium dioxide-titanium dioxide@silicon dioxide added is replaced with 10g of talc powder; all other steps are the same. The subsequent preparation process of the fire-retardant coating is the same as in Example 1.

[0133] The results of the pull-out adhesion, thermal conductivity, fire resistance limit, salt spray resistance and aging resistance tests of the fireproof and heat-insulating coating prepared in this comparative example are shown in Table 1.

[0134] Comparative Example 5

[0135] This comparative example provides a method for preparing a fireproof and heat-insulating coating, which is basically the same as the preparation method in Example 1. The only difference is that the amount of core-shell structure heat-insulating filler added is different in the step of preparing the core-shell structure heat-insulating filler. All other steps are the same.

[0136] In this comparative example, the preparation method of the fire-retardant and heat-insulating coating specifically includes:

[0137] (1) Dissolve 40g of epoxy resin E51 (purchased from Nan Ya Epoxy Resin (Kunshan) Co., Ltd., with a solid content of 100%) in 10g of reactive diluent AGE (purchased from Hubei Green Home Material Technology Co., Ltd., with an epoxy value of 0.32) and stir until homogeneous. Then add 30g of intumescent flame retardant (containing 18g of ammonium polyphosphate, 6g of pentaerythritol and 6g of melamine) to obtain mixture A.

[0138] (2) Add 0.5g of bentonite anti-settling agent and 1.5g of high-temperature resistant carbon fiber (fiber length of 6mm) to the mixture A, stir evenly to obtain mixture B;

[0139] (3) Add 20g of cerium dioxide-titanium dioxide@silicon dioxide to the mixture B, stir evenly, and finally add 30g of polyamide epoxy curing agent (purchased from Dongguan Zhenhe Resin Technology Co., Ltd., with a solid content of 80%), stir evenly, and the fireproof and heat-insulating coating is obtained.

[0140] The results of the pull-out adhesion, thermal conductivity, fire resistance limit, salt spray resistance and aging resistance tests of the fireproof and heat-insulating coating prepared in this comparative example are shown in Table 1.

[0141] Comparative Example 6

[0142] This comparative example provides a method for preparing a fire-retardant and heat-insulating coating, which is basically the same as the preparation method in Example 1. The only difference is that the preparation method of the heat-insulating functional filler provided in this comparative example is basically the same as the preparation method in Example 1. The only difference is that the amount of cerium dioxide and titanium dioxide added is different in the preparation method of the heat-insulating functional filler with a core-shell structure. Specifically, the preparation method of the heat-insulating functional filler includes:

[0143] First, weigh 3 mol of titanium dioxide and 3 mol of cerium dioxide and add them to 500 g of 30 wt% hydrogen peroxide solution. Add 5 drops of 5 wt% acetic acid to adjust the pH of the solution to 3.0. Stir slowly for 10 h under ultraviolet light irradiation. The hydroxyl radicals (·OH) generated by the decomposition of hydrogen peroxide are adsorbed on the surface of cerium dioxide and titanium dioxide, causing them to be hydroxylated. Then, wash with 500 mL of deionized water 5 times and centrifuge to obtain reactant A.

[0144] Then, 1000g of methyltrimethoxysilane was weighed and added to 100g of 0.1mol / L acetic acid solution, and stirred at 200r / min for 2h to obtain silane hydrolysate B.

[0145] Finally, reactant A was added to hydrolysate B, along with 12g of citric acid complexing agent and 1.0g of polyvinylpyrrolidone stabilizer to improve the stability of the sol. The mixture was stirred in a 50°C water bath for 5 hours to form a transparent sol, which was then allowed to stand at room temperature to 25°C for 24 hours to further polymerize and form a stable colloid. The gel was then calcined at 500°C for 5 hours under a nitrogen atmosphere at a heating rate of 5°C / min, yielding a final product of cerium dioxide-titanium dioxide@silicon dioxide with a core-shell structure. The subsequent preparation process for the fire-retardant coating was the same as in Example 1.

[0146] The results of the pull-out adhesion, thermal conductivity, fire resistance limit, salt spray resistance and aging resistance tests of the fireproof and heat-insulating coating prepared in this comparative example are shown in Table 1.

[0147] Comparative Example 7

[0148] This comparative example provides a method for preparing a fire-retardant and heat-insulating coating, which is basically the same as the preparation method in Example 1. The only difference is that the preparation method of the heat-insulating functional filler provided in this comparative example is basically the same as the preparation method in Example 1. The only difference is that the addition method of cerium dioxide and titanium dioxide is different in the preparation method of the heat-insulating functional filler with a core-shell structure. Specifically, the preparation method of the heat-insulating functional filler includes:

[0149] First, weigh 1 mol of cerium dioxide and add it to 500 g of 30wt% hydrogen peroxide solution. Add 5 drops of 5wt% acetic acid to adjust the pH of the solution to ~3.0. Stir slowly for 10 h under ultraviolet light irradiation. The hydroxyl radicals (·OH) generated by the decomposition of hydrogen peroxide are adsorbed on the surface of titanium dioxide, making its surface hydroxylated. Then, wash it 5 times with 500 mL of deionized water and centrifuge to obtain reactant A.

[0150] Then, 1000g of methyltrimethoxysilane was weighed and added to 100g of 0.1mol / L acetic acid solution, and stirred at 200r / min for 2h to obtain silane hydrolysate B.

[0151] Finally, reactant A was added to silane hydrolysate B, along with 12g of citric acid complexing agent and 1.0g of polyvinylpyrrolidone stabilizer to improve the stability of the sol. The mixture was stirred in a 50℃ water bath for 5 hours to form a transparent sol, which was then allowed to stand at room temperature to 25℃ for 24 hours to further polymerize and form a stable colloid. The gel was then calcined at 500℃ for 5 hours under a nitrogen atmosphere at a heating rate of 5℃ / min, yielding a final product of cerium dioxide@silicon dioxide with a core-shell structure.

[0152] The specific methods for preparing fire-retardant and heat-insulating coatings include:

[0153] (1) Dissolve 40g of epoxy resin E51 (purchased from Nan Ya Epoxy Resin (Kunshan) Co., Ltd., with a solid content of 100%) in 10g of reactive diluent AGE (purchased from Hubei Green Home Material Technology Co., Ltd., with an epoxy value of 0.32) and stir evenly. Then add 3g of titanium dioxide and 30g of intumescent flame retardant (containing 18g of ammonium polyphosphate, 6g of pentaerythritol and 6g of melamine) to obtain mixture A;

[0154] (2) Add 0.5g of bentonite anti-settling agent and 1.5g of high-temperature resistant carbon fiber (fiber length of 6mm) to the mixture A, stir evenly to obtain mixture B;

[0155] (3) Add 7g of cerium dioxide@silicon dioxide to the mixture B, stir evenly, and finally add 30g of polyamide epoxy curing agent (purchased from Dongguan Zhenhe Resin Technology Co., Ltd., with a solid content of 80%), stir evenly, and the fireproof and heat-insulating coating is obtained.

[0156] The results of the pull-out adhesion, thermal conductivity, fire resistance limit, salt spray resistance and aging resistance tests of the fireproof and heat-insulating coating prepared in this comparative example are shown in Table 1.

[0157] Comparative Example 8

[0158] This comparative example provides a method for preparing a fire-retardant and heat-insulating coating, which is basically the same as the preparation method in Example 1. The only difference is that the preparation method of the heat-insulating functional filler provided in this comparative example is basically the same as the preparation method in Example 1. The only difference is that the addition method of cerium dioxide and titanium dioxide is different in the preparation method of the heat-insulating functional filler with a core-shell structure. Specifically, the preparation method of the heat-insulating functional filler includes:

[0159] First, weigh 1 mol of titanium dioxide and add it to 500 g of 30wt% hydrogen peroxide solution. Add 5 drops of 5wt% acetic acid to adjust the pH of the solution to 3.0. Stir slowly for 10 h under ultraviolet light irradiation. The hydroxyl radicals (·OH) generated by the decomposition of hydrogen peroxide are adsorbed on the surface of titanium dioxide, making its surface hydroxylated. Then, wash it 5 times with 500 mL of deionized water and centrifuge to obtain reactant A.

[0160] Then, 1000g of methyltrimethoxysilane was weighed and added to 100g of 0.1mol / L acetic acid solution, and stirred at 200r / min for 2h to obtain silane hydrolysate B.

[0161] Finally, reactant A was added to silane hydrolysate B, along with 12g of citric acid complexing agent and 1.0g of polyvinylpyrrolidone stabilizer to improve the stability of the sol. The mixture was stirred in a 50℃ water bath for 5 hours to form a transparent sol, which was then allowed to stand at room temperature to 25℃ for 24 hours to further polymerize and form a stable colloid. The gel was then calcined at 500℃ for 4 hours under a nitrogen atmosphere to obtain a core-shell structured titanium dioxide@silicon dioxide.

[0162] The specific methods for preparing fire-retardant and heat-insulating coatings include:

[0163] (1) Dissolve 40g of epoxy resin E51 (purchased from Nan Ya Epoxy Resin (Kunshan) Co., Ltd., with a solid content of 100%) in 10g of reactive diluent AGE (purchased from Hubei Green Home Material Technology Co., Ltd., with an epoxy value of 0.32) and stir evenly. Then add 3g of cerium dioxide and 30g of intumescent flame retardant (containing 18g of ammonium polyphosphate, 6g of pentaerythritol and 6g of melamine) to obtain mixture A;

[0164] (2) Add 0.5g of bentonite anti-settling agent and 1.5g of high-temperature resistant carbon fiber (fiber length is 6mm) to the mixture A, stir evenly to obtain mixture B;

[0165] (3) Add 7g of titanium dioxide@silicon dioxide to the mixture B, stir evenly, and finally add 30g of polyamide epoxy curing agent (purchased from Dongguan Zhenhe Resin Technology Co., Ltd., with a solid content of 80%), stir evenly, and the fireproof and heat-insulating coating is obtained.

[0166] The results of the pull-out adhesion, thermal conductivity, fire resistance limit, salt spray resistance and aging resistance tests of the fireproof and heat-insulating coating prepared in this comparative example are shown in Table 1.

[0167] Comparative Example 9

[0168] The only difference between this comparative example and Example 1 is the high-temperature sintering process. This comparative example includes adding reactant A to hydrolysate B, adding 12g of citric acid complexing agent, and adding 1.0g of polyvinylpyrrolidone stabilizer to improve the stability of the sol; stirring in a 50°C water bath for 5 hours to form a transparent sol, and allowing it to stand at room temperature to 25°C for 24 hours to allow the sol to further polymerize and form a stable colloid; calcining the gel in a nitrogen atmosphere at a heating rate of 3.5°C / min to 500°C for 5 hours, and finally obtaining a cerium dioxide-titanium dioxide@silica powder with a core-shell structure.

[0169] The cerium dioxide-titanium dioxide@silicon dioxide powder obtained in this comparative example was observed by electron microscopy. The proportion of the fully encapsulated core-shell structure was about 90-95%.

[0170] The results of the pull-out adhesion, thermal conductivity, fire resistance limit, salt spray resistance and aging resistance tests of the fireproof and heat-insulating coating prepared in this comparative example are shown in Table 1.

[0171] Comparative Example 10

[0172] The only difference between this comparative example and Example 1 is the high-temperature sintering process. This comparative example includes adding reactant A to hydrolysate B, adding 12g of citric acid complexing agent, and adding 1.0g of polyvinylpyrrolidone stabilizer to improve the stability of the sol; stirring in a 50°C water bath for 5 hours to form a transparent sol, and allowing it to stand at room temperature to 25°C for 24 hours to allow the sol to further polymerize and form a stable colloid; calcining the gel in a nitrogen atmosphere at a heating rate of 8°C / min to 500°C for 5 hours, and finally obtaining a cerium dioxide-titanium dioxide@silicon dioxide product with a core-shell structure.

[0173] Electron microscopy images of the cerium dioxide-titanium dioxide@silicon dioxide powder in this comparative example show that the proportion of fully encapsulated core-shell structures is approximately 60-70%.

[0174] The results of the pull-out adhesion, thermal conductivity, fire resistance limit, salt spray resistance and aging resistance tests of the fireproof and heat-insulating coating prepared in this comparative example are shown in Table 1.

[0175] Table 1. Comprehensive physical properties of the fire-retardant and heat-insulating coatings provided in the examples and comparative examples.

[0176]

[0177] The results of the pull-out adhesion, thermal conductivity, fire resistance limit, salt spray resistance and aging resistance tests of the fireproof and heat-insulating coating prepared in this embodiment are shown in Table 1.

[0178] As shown in Table 1, the fireproof and heat-insulating coating prepared in Example 1 has an adhesion rating of 0, a thermal conductivity of 0.07 W / (m·K), a fire resistance limit of 2.5 h, a salt spray resistance of 1000 h, and an aging resistance of 800 h, indicating that the fireproof and heat-insulating coating provided by this invention has good comprehensive protective performance. Simultaneously, the back temperature of carbon steel burned in an acetylene flame decreased to an average of ~280℃ within 180 min. The coating prepared in Example 1 exhibits good fireproof and heat-insulating effects, mainly because, on the one hand, the silanol groups on the surface of silica obtained by high-temperature sintering form hydrogen bonds with pentaerythritol, enhancing the compatibility between silica and the components of the coating; on the other hand, titanium dioxide in fireproof coatings has multiple functions including heat insulation, flame retardancy, smoke suppression, and weather resistance, while cerium dioxide can stabilize the expanded carbon layer structure and improve the fire resistance limit.

[0179] By comparing the test results of Example 1, Example 2 and Comparative Example 4, it is shown that the more cerium dioxide-titanium dioxide@silica powder is added, the better the heat insulation performance of the fireproof and heat-insulating coating and the longer the aging resistance time. However, the pull-out adhesion of the paint film decreases, mainly because the pigment-binder ratio in the fireproof coating formulation increases, resulting in a decrease in paint film adhesion.

[0180] By comparing the test results of Example 1 and Example 3, it was found that when the amount of cerium dioxide added increased, the fire resistance time of the prepared coating was extended to 3 hours. However, from a cost perspective, the higher the amount of cerium dioxide added, the higher the formulation cost of the coating also increased.

[0181] By comparing the test results of Examples 1, 4, and 5, it was found that when the amount of silica added increased, the fire resistance limit and fire rating of the prepared fire-retardant coating remained unchanged, and the heat insulation performance of the fire-retardant coating improved, but the density of the coating decreased, which in turn reduced the adhesion and salt spray resistance of the fire-retardant coating. This indicates that by increasing the proportion of silica added, the present invention can increase the proportion of cerium dioxide and titanium dioxide fully coated. However, during the calcination process, the coated gel shell is damaged by high temperature, resulting in the shell being broken and causing the cerium dioxide and titanium dioxide particles to be partially dispersed outside the core-shell structure, forming a semi-coated core-shell structure.

[0182] Comparing the test results of Example 1 and Comparative Example 1, it is shown that adding cerium dioxide@silica powder reduces the aging resistance and heat insulation performance of the fireproof and heat-insulating coating, but does not reduce the fire resistance limit time. This indicates that titanium dioxide helps improve the aging resistance of the fireproof and heat-insulating coating, while also providing some heat insulation benefits.

[0183] Comparing the test results of Example 1 and Comparative Example 2, it is shown that adding titanium dioxide@silica powder reduces the fire resistance limit of the prepared fireproof and heat-insulating coating from 2.5h to 2.0h, and increases the thermal conductivity to 0.11W / (m·K). This indicates that cerium dioxide has a synergistic effect on flame-retardant expanders, mainly because cerium dioxide can exert a synergistic effect in expandable flame-retardant systems through multiple pathways such as catalytic char formation, free radical capture, and acid source stabilization.

[0184] Comparing the test results of Example 1 and Comparative Example 3, it is shown that when only silica powder is added, the thermal conductivity of the prepared fireproof and heat-insulating coating does not change significantly, but the fire resistance limit decreases, the aging resistance decreases to 700h, and the salt spray resistance time decreases to 900h. When the coating does not contain core-shell structured heat-insulating fillers, the fire resistance limit of the fireproof coating decreases; however, the addition of core-shell structured heat-insulating fillers has a negative impact on the salt spray resistance of the coating, mainly because the core-shell structured heat-insulating fillers reduce the density of the paint film.

[0185] Comparing the test results of Example 1, Comparative Example 4, and Comparative Example 5, the absence of a core-shell structured fire-resistant and heat-insulating filler resulted in a decrease in the fire resistance limit and aging resistance of the prepared coating, but an improvement in the adhesion and salt spray resistance. When the content of the core-shell structured fire-resistant and heat-insulating filler was too high, the adhesion and salt spray resistance of the prepared fire-resistant and heat-insulating coating decreased. This indicates that the core-shell structured functional filler prepared in this invention can increase the heat insulation performance of the paint film, but it also reduces the density of the paint film.

[0186] By comparing the test results of Example 1 and Comparative Example 6, in the preparation step of the core-shell structure cerium dioxide-titanium dioxide@silicon dioxide, when the relative content of cerium dioxide and titanium dioxide increases, the amount of uncoated cerium dioxide and titanium dioxide in the core-shell structure increases, leading to an increase in the thermal conductivity of the prepared coating, a decrease in thermal insulation performance, no change in fire resistance limit and fire rating, and an improvement in the coating's salt spray resistance and aging resistance. This indicates that a fully coated core-shell structure can improve the thermal insulation performance of the epoxy coating; adding excess uncoated cerium dioxide and titanium dioxide directly to the epoxy resin can improve the epoxy coating's aging resistance and salt spray resistance.

[0187] By comparing the test results of Example 1, Comparative Example 7, and Comparative Example 8, it was found that when some titanium dioxide or cerium dioxide was directly added to the epoxy resin, the thermal conductivity of the prepared fire-retardant coating increased (i.e., the heat insulation performance decreased), while the fire resistance limit remained unchanged. However, the aging resistance of Comparative Example 7 improved. This indicates that encapsulating titanium dioxide or cerium dioxide inside silica is more beneficial for improving the heat insulation performance of the epoxy fire-retardant coating, while directly adding titanium dioxide is more beneficial for improving the aging resistance of the coating.

[0188] By comparing the test results of Example 1, Comparative Example 9, and Comparative Example 10, it was found that the proportion of the fully encapsulated core-shell structure varied with different heating rates. When the heating rate was 8°C / min, the proportion of the fully encapsulated core-shell structure was approximately 50-60%; when the heating rate was 3.5°C / min, the proportion was approximately 90-95%. Increasing the proportion of the fully encapsulated core-shell structure resulted in a lower thermal conductivity, improved heat insulation performance, and reduced aging resistance of the prepared fire-retardant coating. Conversely, decreasing the proportion of the fully encapsulated core-shell structure to 50-60% resulted in a higher thermal conductivity and reduced heat insulation performance of the prepared fire-retardant coating. The heating rate during high-temperature sintering had a significant impact on the performance of the prepared fire-retardant coating.

[0189] In summary, the cerium dioxide-titanium dioxide@silica powder with a combination of full and partial coating obtained by adopting the technical solution of the present invention has excellent comprehensive performance. The proportion of the fully coated core-shell structure in the powder can be controlled by controlling the sintering process conditions of the coated gel, and the heat insulation and aging resistance of the functional filler can be controlled by adjusting the content of exposed cerium dioxide and titanium dioxide.

[0190] The above description of the embodiments is intended to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a functional filler, characterized in that, This includes using the sol-gel method and high-temperature sintering technology to coat cerium dioxide and titanium dioxide inside silicon dioxide to form a core-shell structure; Specifically, the process involves: dispersing cerium dioxide and titanium dioxide in a hydrogen peroxide aqueous solution for surface hydroxylation; then, adding a small molecule silane solution to react and form a sol, in which cerium dioxide and titanium dioxide are encapsulated; adding a complexing agent and a stabilizer; heating in a water bath to form a transparent gel; and finally, sintering the gel at high temperature under a nitrogen atmosphere to obtain the functional filler. The core-shell structure is composed of a fully enclosed core-shell structure and a semi-enclosed core-shell structure, wherein the fully enclosed core-shell structure accounts for 70-80% of the functional filler. The high-temperature sintering process involves reacting under a nitrogen atmosphere at a heating rate of 5°C / min, heating to 400-500°C, holding at that temperature for 5-10 hours, and then annealing to obtain the functional filler.

2. The preparation method according to claim 1, characterized in that, The small molecule silane solution is obtained by hydrolyzing methyltrimethoxysilane, methyltriethoxysilane, and isobutyltrimethoxysilane in an acidic solution; And / or, the concentration of the hydrogen peroxide aqueous solution is 25~40 wt%; And / or, the complexing agent is citric acid; And / or, the stabilizer is polyvinylpyrrolidone; And / or, the mass ratio of the complexing agent to the stabilizer is 10~15:1; And / or, the water bath heating temperature is 40~50℃.

3. The preparation method according to claim 1, characterized in that, In the functional filler, the molar ratio of cerium dioxide:titanium dioxide:silicon dioxide is (1~2):(1~2):(1~50). And / or, the hydroxylation includes: adding cerium dioxide and titanium dioxide to a hydrogen peroxide aqueous solution, adding an acidic solution to adjust the solution to pH ~3.0, and slowly stirring under ultraviolet light for 5 ~ 10 h, so that the hydroxyl radicals ·OH generated by the decomposition of hydrogen peroxide are adsorbed on the surface of cerium dioxide and titanium dioxide to achieve hydroxylation.

4. A functional filler, prepared by the preparation method according to any one of claims 1-3.

5. A fire-retardant and heat-insulating coating, characterized in that, It includes at least the functional filler as described in claim 4.

6. The fireproof and heat-insulating coating according to claim 5, characterized in that, It includes at least the core-shell heat-insulating filler, intumescent flame retardant, organic solvent, additives, epoxy resin and epoxy curing agent.

7. The fireproof and heat-insulating coating according to claim 6, characterized in that, The additives include one or a combination of anti-settling bentonite and high-temperature resistant carbon fiber. And / or, the organic solvent is the reactive diluent AGE; And / or, the epoxy resin is one or a combination of pure epoxy resin, silicone-modified epoxy resin, and acrylic-modified epoxy resin. And / or, the solid content of the epoxy resin is 75-100%; And / or, the epoxy curing agent is one or a combination of polyamide curing agent, phenolic amine curing agent, and alicyclic amine curing agent; And / or, the mass ratio of the functional filler to the epoxy resin is 1~2:10; And / or, the mass ratio of the functional filler to the intumescent flame retardant is 1~2:

5.

8. The fire-retardant and heat-insulating coating according to any one of claims 5-7, characterized in that, By weight, it includes: 40-50 parts epoxy resin, 5-10 parts functional filler, 25-50 parts intumescent flame retardant, 10-20 parts organic solvent, 0.5-2.0 parts additives, and 30-40 parts epoxy curing agent.

9. A method for preparing a fire-retardant and heat-insulating coating as described in any one of claims 5-8, characterized in that, The specific steps include the following: S1. Dissolve the epoxy resin in an organic solvent and stir until homogeneous to obtain mixture A; S2. Add the additive to the mixture A, stir until homogeneous, and obtain mixture B; S3. Add the functional filler and intumescent flame retardant to the mixture B, stir at high speed, then add the epoxy curing agent and stir evenly to obtain the fireproof and heat-insulating coating.

10. A fireproof and heat-insulating coating, comprising spraying the fireproof and heat-insulating coating as described in any one of claims 5-8 onto the surface of a metal or carbon steel substrate, and curing it to form a paint film, thereby obtaining the fireproof and heat-insulating coating; And / or, the thickness of the fireproof and heat-insulating coating is 5~10mm; And / or, the pull-out adhesion is 5~6MPa; the thermal conductivity is ≤0.09W / (m·K); the fire resistance limit is ≥2.5h; and the fire rating is A1.

11. The application of a fire-retardant and heat-insulating coating as described in any one of claims 5-8 on the surface of steel structures and aluminum alloy materials.

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