Indoor non-intumescent fireproof coating for steel structure and preparation method of indoor non-intumescent fireproof coating

Abstract

The invention discloses an indoor non-intumescent fire retardant coating for a steel structure and a preparation method of the indoor non-intumescent fire retardant coating. The fireproof coating is prepared from desulfurized gypsum, zinc borosilicate glass powder, metakaolin, hollow ceramic microbeads, fire-resistant fine filler, high-temperature-resistant fibers, a water-retention thickening aid, an organic water repellent, a dispersing agent and water. The zinc borosilicate glass powder, the metakaolin and the hollow ceramic microbeads jointly form a fire crack sealing, consolidation and heat insulation synergistic system, so that the coating seals surface cracks, opens pores and promotes surface consolidation through a liquid phase in the fire process, and meanwhile, an internal light heat insulation framework is maintained. The fireproof coating has the advantages of good fire resistance, high integrity after burning and good heat insulation effect, and is suitable for indoor fireproof protection of steel beams, steel columns, steel joints and steel floor support plates.

Description

Technical Field

[0001] This invention relates to the field of fire-retardant coating technology, and in particular to an indoor non-intumescent fire-retardant coating for steel structures and its preparation method. Background Technology

[0002] Steel structures are widely used in industrial plants, public buildings, and prefabricated buildings due to their high load-bearing capacity and fast construction speed. However, steel heats up quickly under fire conditions, and its mechanical properties decrease significantly with increasing temperature. Therefore, a fire-resistant protective layer is usually required on its surface. Indoor non-intumescent fire-retardant coatings for steel structures offer advantages such as convenient application, good durability, and strong adaptability to various finishes, making them one of the important technical approaches for fire protection of steel structures.

[0003] Existing indoor non-intumescent fire-retardant coatings for steel structures mostly employ inorganic cementitious materials combined with lightweight insulating fillers to achieve thermal insulation protection. Their fire-retardant mechanism mainly relies on the coating thickness and the inhibitory effect of low thermal conductivity components on heat transfer. Although this technology can delay the heating of the steel substrate to a certain extent, during fire exposure, cracks and open pores easily form on the coating surface, causing heat to be rapidly transferred along the cracks and pores, thus affecting the integrity of the coating and its fire-retardant effect.

[0004] Therefore, existing technologies still need to provide an indoor non-intumescent fireproof coating for steel structures that, while maintaining the workability and thermal insulation of the non-intumescent system, can seal surface cracks and open pores during fire exposure and promote surface consolidation, thereby improving the fire integrity of the coating and its fire protection capability for steel structures. Summary of the Invention

[0005] To address the aforementioned issues, this invention proposes an indoor non-expansion fireproof coating for steel structures and its preparation method. The coating employs zinc borosilicate glass powder, metakaolin, and hollow ceramic microspheres to form a fire-resistant crack-sealing, consolidation, and heat-insulating synergistic system. This system allows the coating to seal surface cracks and open pores through a liquid phase during fire exposure, promoting surface consolidation while maintaining an internal lightweight heat-insulating framework.

[0006] This invention can be achieved through the following technical solutions: An indoor non-expansion fireproof coating for steel structures, by weight, comprises: 50-60 parts desulfurized gypsum, 8-20 parts zinc borosilicate, 8-20 parts metakaolin, 10-25 parts hollow ceramic microspheres, 5-15 parts refractory fine filler, 0.2-2 parts high-temperature resistant fiber, 0.1-1.5 parts water-retaining and thickening agent, 0.1-1 parts dispersant, 0.3-1.5 parts organic water-repellent agent, and 20-60 parts water; wherein, the zinc borosilicate glass powder is a low-temperature liquid phase forming component under fire, the metakaolin is a liquid phase consolidation promoting component, and the hollow ceramic microspheres are a lightweight heat-insulating skeleton component; the zinc borosilicate glass powder, metakaolin, and hollow ceramic microspheres together constitute a fire-resistant crack-sealing, consolidation, and heat-insulating synergistic system, enabling the non-expansion coating formed by the fireproof coating to seal surface cracks and open pores and promote surface consolidation during the fire process, while maintaining the internal lightweight heat-insulating skeleton.

[0007] Preferably, the median particle size of the zinc borosilicate glass powder is 1-30 μm, and the median particle size of the metakaolin is 0.5-10 μm.

[0008] Preferably, the hollow ceramic microspheres have a particle size of 20-120 μm and a bulk density of 0.2-0.8 g / cm3.

[0009] Preferably, the refractory fine filler is one or more of silica fume, calcined kaolin, alumina powder, and quartz powder; the high-temperature resistant fiber is one or more of basalt fiber, ceramic fiber, and aluminosilicate fiber.

[0010] Preferably, the water-retaining and thickening agent is a cellulose ether, the dispersant is a polycarboxylate dispersant or a lignin sulfonate dispersant, and the organic hydrophobic agent is selected from organosilicon hydrophobic agents or calcium stearate.

[0011] A method for preparing an indoor non-intumescent fire-retardant coating for steel structures is as follows: Step 1: Mix desulfurized gypsum, zinc borosilicate glass powder, metakaolin, refractory fine filler, and high-temperature resistant fiber to obtain powder. Step 2: Mix the water-retaining and thickening agent, organic water-repellent agent, dispersant and water to obtain a liquid. Step 3: After adding the powder to the liquid and stirring, add hollow ceramic microspheres and perform low-shear mixing for 1-10 minutes to obtain an indoor non-expansion steel structure fireproof coating.

[0012] Preferably, the fire-retardant coating is applied to the surface of the steel structure substrate and cured to form a single-layer non-intumescent fire-retardant coating.

[0013] Preferably, the fire-retardant coating forms a crack-sealing and solidified surface layer and a heat-insulating inner layer after being exposed to fire.

[0014] The beneficial effects of this invention are: This invention constructs a "fire-resistant crack-sealing, consolidation, and heat-insulating synergistic system" by introducing zinc borosilicate glass powder, metakaolin, and hollow ceramic microspheres into a non-intumescent fire-retardant coating system. The zinc borosilicate glass powder forms a low-temperature liquid phase during fire exposure, which seals surface cracks and open pores. Metakaolin promotes further consolidation of the liquid phase, forming a continuous and stable consolidation layer on the coating surface. The hollow ceramic microspheres, added later and mixed using a low-shear process, maintain their structural integrity, forming a stable, lightweight, porous heat-insulating framework after fire exposure. Through these synergistic effects, the coating simultaneously achieves liquid phase crack sealing, surface consolidation, and maintenance of the internal heat-insulating framework during fire exposure, significantly improving the coating's structural integrity and fire resistance stability.

[0015] Therefore, the fire-retardant coating prepared by this invention exhibits better structural integrity and stability under fire conditions, with a surface layer less prone to cracking and peeling, and good internal thermal insulation performance, thereby effectively reducing heat transfer to the steel substrate and significantly improving fire resistance. Compared to the comparative example lacking any key component, this invention demonstrates significant advantages in fire resistance limit, post-burning bulk density, pore structure retention, and thermal conductivity, achieving a comprehensive improvement in fire resistance, thermal insulation, and coating stability, and is suitable for fire protection of various indoor steel structures. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 The fire resistance limit of fire-retardant coating applied to the surface of a steel plate substrate; Figure 2 The volumetric density, total pore volume, and average pore diameter after burning of fire-retardant coating applied to the surface of a steel plate substrate; Figure 3 The thermal conductivity after burning of fire-retardant coating applied to the surface of a steel plate substrate. Detailed Implementation

[0017] The following provides a detailed description of the embodiments of the present invention: These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and processes. However, the scope of protection of the present invention is not limited to the following embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions.

[0018] Example 1: A method for preparing an indoor non-intumescent fire-retardant coating for steel structures is as follows: Step 1: By weight, take 50 parts desulfurized gypsum, 8 parts zinc borosilicate glass powder, 8 parts metakaolin, 10 parts hollow ceramic microspheres, 5 parts refractory fine filler, 0.2 parts high-temperature resistant fiber, 0.1 parts water-retaining and thickening agent, 0.3 parts organic water-repellent agent, 0.1 parts dispersant, and 20 parts water; wherein, the median particle size of zinc borosilicate glass powder is 1 μm, the median particle size of metakaolin is 0.5 μm, the particle size of hollow ceramic microspheres is 20 μm, the bulk density is 0.2 g / cm3, the refractory fine filler is silica fume, the high-temperature resistant fiber is basalt fiber, the water-retaining and thickening agent is cellulose ether, the organic water-repellent agent is organosilicon water-repellent agent, and the dispersant is polycarboxylate dispersant; Step 2: Mix desulfurized gypsum, zinc borosilicate glass powder, metakaolin, silica fume and basalt fiber to obtain powder; mix cellulose ether, organosilicon water-repellent agent, polycarboxylate dispersant and water to obtain liquid; add powder to liquid and stir to mix evenly, then add hollow ceramic microspheres and perform low-shear mixing for 1 minute to obtain indoor non-expansion steel structure fireproof coating.

[0019] Example 2: A method for preparing an indoor non-intumescent fire-retardant coating for steel structures is as follows: Step 1: By weight, take 55 parts desulfurized gypsum, 14 parts zinc borosilicate glass powder, 14 parts metakaolin, 17.5 parts hollow ceramic microspheres, 10 parts refractory fine filler, 1.1 parts high-temperature resistant fiber, 0.8 parts water-retaining and thickening agent, 0.9 parts organic water-repellent agent, 0.55 parts dispersant, and 40 parts water; wherein, the median particle size of zinc borosilicate glass powder is 15.5 μm, the median particle size of metakaolin is 5.25 μm, the particle size of hollow ceramic microspheres is 70 μm, the bulk density is 0.5 g / cm3, the refractory fine filler is alumina micro powder, the high-temperature resistant fiber is aluminosilicate fiber, the water-retaining and thickening agent is cellulose ether, the organic water-repellent agent is organosilicon water-repellent agent, and the dispersant is lignin sulfonate dispersant; Step 2: Mix desulfurized gypsum, zinc borosilicate glass powder, metakaolin, alumina micro powder and aluminum silicate fiber to obtain powder; mix cellulose ether, organosilicon water-repellent agent, lignin sulfonate dispersant and water to obtain liquid; add powder to liquid and stir to mix evenly, then add hollow ceramic microspheres and perform low-shear mixing for 5 minutes to obtain indoor non-expansion steel structure fireproof coating.

[0020] Example 3: A method for preparing an indoor non-intumescent fire-retardant coating for steel structures is as follows: Step 1: By weight, take 60 parts desulfurized gypsum, 20 parts zinc borosilicate glass powder, 20 parts metakaolin, 25 parts hollow ceramic microspheres, 15 parts refractory fine filler, 2 parts high-temperature resistant fiber, 1.5 parts water-retaining and thickening agent, 1.5 parts organic water-repellent agent, 1 part dispersant, and 60 parts water; wherein, the median particle size of zinc borosilicate glass powder is 30 μm, the median particle size of metakaolin is 10 μm, the particle size of hollow ceramic microspheres is 120 μm, the bulk density is 0.8 g / cm3, the refractory fine filler is quartz powder, the high-temperature resistant fiber is aluminosilicate fiber, the water-retaining and thickening agent is cellulose ether, the organic water-repellent agent is organosilicon water-repellent agent, and the dispersant is lignin sulfonate dispersant; Step 2: Mix desulfurized gypsum, zinc borosilicate glass powder, metakaolin, quartz powder and aluminum silicate fiber to obtain powder; mix cellulose ether, organosilicon water-repellent agent, lignin sulfonate dispersant and water to obtain liquid; add powder to liquid and stir to mix evenly, then add hollow ceramic microspheres and perform low-shear mixing for 10 minutes to obtain indoor non-expansion steel structure fireproof coating.

[0021] Example 4: A method for preparing an indoor non-intumescent fire-retardant coating for steel structures is as follows: Step 1: By weight, take 52 parts of desulfurized gypsum, 12 parts of zinc borosilicate glass powder, 10 parts of metakaolin, 20 parts of hollow ceramic microspheres, 8 parts of refractory fine filler, 0.8 parts of high-temperature resistant fiber, 0.5 parts of water-retaining and thickening agent, 0.6 parts of organic water-repellent agent, 0.3 parts of dispersant, and 30 parts of water; wherein, the median particle size of zinc borosilicate glass powder is 10 μm, the median particle size of metakaolin is 3 μm, the particle size of hollow ceramic microspheres is 50 μm, the bulk density is 0.4 g / cm3, the refractory fine filler is calcined kaolin, the high-temperature resistant fiber is ceramic fiber, the water-retaining and thickening agent is cellulose ether, the organic water-repellent agent is calcium stearate, and the dispersant is lignin sulfonate dispersant; Step 2: Mix desulfurized gypsum, zinc borosilicate glass powder, metakaolin, calcined kaolin and ceramic fiber to obtain powder; mix cellulose ether, calcium stearate, lignin sulfonate dispersant and water to obtain liquid; add powder to liquid and stir to mix evenly, then add hollow ceramic microspheres and perform low-shear mixing for 10 minutes to obtain indoor non-expansion steel structure fireproof coating.

[0022] Comparative Example 1: The difference between this comparative example and Example 1 is that zinc borosilicate glass powder is missing; the rest of the steps are the same as in Example 1.

[0023] Comparative Example 2: The difference between this comparative example and Example 1 is that it lacks metakaolin, while the other steps are the same as in Example 1.

[0024] Comparative Example 3: The difference between this comparative example and Example 1 is that desulfurized gypsum, hollow ceramic microspheres, zinc borosilicate glass powder, metakaolin, refractory fine filler and high-temperature resistant fiber are mixed together.

[0025] Comparative Example 4: The difference between this comparative example and Example 1 is the absence of an organic hydrophobic agent; the remaining steps are the same as in Example 1.

[0026] Performance testing Sample preparation: The fire-retardant coatings obtained in Examples 1-4 and Comparative Examples 1-4 were applied to the surface of steel plate substrates after sandblasting and rust removal. The wet film thickness was controlled to be consistent. After curing at room temperature for 24 hours, the coatings were dried at 60°C to constant weight to obtain test samples.

[0027] 1. Fire resistance test The fire resistance of the test specimens was determined in accordance with GB 14907-2018 standard.

[0028] 2-pore structure and bulk density test The pore structure of the calcined samples was analyzed by mercury intrusion porosimetry, and the total pore volume, average pore size and pore size distribution were measured. At the same time, the changes in bulk density of the samples before and after calcination were measured.

[0029] 3 Thermal conductivity test Take a block sample after firing and use a thermal conductivity meter to measure its thermal conductivity at room temperature.

[0030] Table 1 Performance test results of the samples

[0031] As shown in Table 1, Examples 1-4 all exhibited superior overall performance, with a fire resistance limit of 128-162 min, significantly higher than the comparative example. The post-firing bulk density remained at 0.53-0.59 g / cm³, the total pore volume was 0.82-1.05 mL / g, the average pore size was 7.6-9.8 μm, and the post-firing thermal conductivity decreased to 0.096-0.121 W / m·K. This indicates that the "fire-resistant crack-sealing, consolidation, and heat-insulating synergistic system" composed of zinc borosilicate glass powder, metakaolin, and hollow ceramic microspheres in this invention truly achieves the triple effect of the inventive concept: firstly, the zinc borosilicate glass powder forms a low-temperature liquid phase during firing, which is beneficial for sealing surface cracks and opening pores; secondly, the metakaolin promotes further consolidation of the liquid phase, resulting in a more stable consolidation layer on the surface; and thirdly, the post-addition process of the hollow ceramic microspheres preserves their integrity, thus maintaining a lightweight porous heat-insulating framework after firing.

[0032] In contrast, Comparative Example 1, lacking zinc borosilicate glass powder, had a refractoriness limit reduced to 101 min, a total pore volume reduced to 0.61 mL / g, and a thermal conductivity increased to 0.156 W / m·K. This indicates that without the "low-temperature liquid phase forming component," the coating could not effectively achieve liquid phase sealing, and the surface integrity and heat resistance were significantly reduced. Comparative Example 2, lacking metakaolin, still had a refractoriness limit significantly lower than the example, and had the highest bulk density and low pore volume after firing. This indicates that without the "liquid phase consolidation promoting component," it was difficult to form a stable and continuous surface consolidation structure. Comparative Example 3, with hollow ceramic microspheres under improper processing... The first example, lacking organic water-repellent agent, suffered from a reduced fire resistance limit of only 116 min, the lowest total pore volume, and the highest thermal conductivity. The second example, lacking organic water-repellent agent, had a fire resistance limit of 121 min, a post-fire bulk density of 0.62 g / cm3, a total pore volume of 0.78 mL / g, and a post-fire thermal conductivity of 0.128 W / m·K. This indicates that the absence of "waterproof and impermeable components" makes the coating prone to water absorption and moisture absorption. The vaporization of moisture damages the integrity of the pore structure, resulting in damage to the hollow ceramic microsphere insulation skeleton, weakened liquid phase sealing and surface consolidation effects, and a significant reduction in fire resistance limit and insulation performance.

[0033] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An indoor non-expansive fireproof coating for steel structures, characterized in that, By weight, it comprises: 50-60 parts desulfurized gypsum, 8-20 parts zinc borosilicate, 8-20 parts metakaolin, 10-25 parts hollow ceramic microspheres, 5-15 parts refractory fine filler, 0.2-2 parts high-temperature resistant fiber, 0.1-1.5 parts water-retaining and thickening agent, 0.1-1 parts dispersant, 0.3-1.5 parts organic water-repellent agent, and 20-60 parts water; wherein, the zinc borosilicate glass powder is a low-temperature liquid phase forming component under fire, the metakaolin is a liquid phase consolidation promoting component, and the hollow ceramic microspheres are a lightweight heat-insulating skeleton component; the zinc borosilicate glass powder, metakaolin, and hollow ceramic microspheres together constitute a fire-resistant crack-sealing, consolidation, and heat-insulating synergistic system, enabling the non-expansive coating formed by the curing of the fireproof coating to seal surface cracks and open pores and promote surface consolidation during the fire process, while maintaining the internal lightweight heat-insulating skeleton.

2. The indoor non-expansion fireproof coating for steel structures according to claim 1, characterized in that, The median particle size of the zinc borosilicate glass powder is 1-30 μm, and the median particle size of the metakaolin is 0.5-10 μm.

3. The indoor non-intumescent fireproof coating for steel structures according to claim 1, characterized in that, The hollow ceramic microspheres have a particle size of 20-120 μm and a bulk density of 0.2-0.8 g / cm3.

4. The indoor non-expansion fireproof coating for steel structures according to claim 1, characterized in that, The refractory fine filler is one or more of silica fume, calcined kaolin, alumina powder, and quartz powder; the high-temperature resistant fiber is one or more of basalt fiber, ceramic fiber, and aluminosilicate fiber.

5. The indoor non-intumescent fireproof coating for steel structures according to claim 1, characterized in that, The water-retaining and thickening agent is a cellulose ether, the dispersant is a polycarboxylate dispersant or a lignin sulfonate dispersant, and the organic hydrophobic agent is selected from organosilicon hydrophobic agents or calcium stearate.

6. An indoor non-expansion fireproof coating for steel structures as described in any one of claims 1-5, characterized in that, The fire-retardant coating is prepared as follows: Step 1: Mix desulfurized gypsum, zinc borosilicate glass powder, metakaolin, refractory fine filler, and high-temperature resistant fiber to obtain powder. Step 2: Mix the water-retaining and thickening agent, organic water-repellent agent, dispersant and water to obtain a liquid. Step 3: After adding the powder to the liquid and stirring, add hollow ceramic microspheres and perform low-shear mixing for 1-10 minutes to obtain an indoor non-expansion steel structure fireproof coating.

7. The indoor non-expansion fireproof coating for steel structures according to claim 1, characterized in that, The fire-retardant coating is applied to the surface of the steel structure substrate and cured to form a single-layer non-expansive fire-retardant coating.

8. The indoor non-intumescent fireproof coating for steel structures according to claim 1, characterized in that, The fire-retardant coating forms a crack-sealing and solidified surface layer and a heat-insulating inner layer after being exposed to fire.

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