A rare earth synergistic thin intumescent fireproof coating and a preparation method thereof

Abstract

The application discloses a rare earth synergistic thin expansion steel structure fireproof coating and a preparation method thereof. The coating is prepared from the following raw material components in parts by weight: modified polyvinyl acetate emulsion 16-24 parts by weight, intumescent flame retardant 22-26 parts by weight, flaky cerium oxide 4-8 parts by weight, dihydrogen rare earth phosphate 6-10 parts by weight, titanium white 4-8 parts by weight, kaolin 2-5 parts by weight, talc 2-5 parts by weight, long glass fiber 1-3 parts by weight, auxiliary agent 3-6 parts by weight and pure water 21.5-24 parts by weight. The application reacts with ammonium polyphosphate and cooperates with the flaky cerium oxide to achieve the heat insulation effect, thereby guaranteeing the strength of the carbon layer and improving the heat resistance of the carbon layer, so that the fireproof effect of the application is enhanced, and the performance reaches the requirement of the national standard.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fireproof coating, and particularly relates to a rare earth synergistic thin-type expanded steel structure fireproof coating and a preparation method thereof. BACKGROUND

[0002] Solvent-based thin-type steel structure fireproof coating contains a large amount of volatile organic compounds (VOC), which is easy to emit toxic and polluting substances during production and application, so its use is increasingly restricted. Water-based thin-type steel structure fireproof coating uses water-based polymer as film-forming material, which not only reduces the emission of VOC, reduces the harm to human body and pollution to the environment in the production, construction, application and other links, but also maintains good fire-retardant and fireproof performance, has environmental protection and safety characteristics, and is the focus of fireproof coating research.

[0003] CN 112961528 A discloses a water-based environmentally friendly fireproof coating and a preparation method thereof. The environmentally friendly fireproof coating comprises the following raw materials by weight percentage: high molecular emulsion film-forming material, inorganic film-forming material, expanded organic flame retardant, non-expanded inorganic thermal insulation filler, expanded inorganic thermal insulation filler, reinforcing fiber, nano rare earth oxide, coupling agent, film-forming aid, dispersant, thickening agent, pH regulator, deionized water, etc. The expanded inorganic thermal insulation filler is expandable graphite. The fire resistance limit is 98.3 min, and the expansion ratio is 48. CN 116694190 A discloses an expanded water-based epoxy steel structure fireproof coating, which is composed of the following components by weight percentage: 35%-50% water-based epoxy emulsion, 21%-33% ammonium polyphosphate, 7%-15% expandable graphite, 5%-8% titanium dioxide, 6%-14% floating beads, 6%-14% basalt flake, 0.5%-5% eggshell powder, 1%-3% rare earth oxide, 1%-10% curing agent, etc. The rare earth oxide is lanthanum oxide and cerium oxide. The backboard temperature exceeds 203℃ after burning for 30 min, and the expansion ratio is 11.3.

[0004] The above existing fireproof coatings all involve expandable graphite, which is a black filler that is easy to scatter after burning, which can cause the carbon layer to fall off and scatter, affecting the heat insulation effect of the carbon layer. At the same time, it is difficult to eliminate the black color of expandable graphite, making it difficult to prepare light-colored coatings based on the above fireproof coatings. In addition, the fire resistance limit or expansion ratio of the above two fireproof coatings does not meet the standard requirements of GB 14907-2018. SUMMARY

[0005] The present application aims to overcome the defects of the prior art and provide a rare earth synergistic thin-type expanded steel structure fireproof coating.

[0006] Another object of the present application is to provide a preparation method of the above-mentioned rare earth synergistic thin-type expanded steel structure fireproof coating.

[0007] The technical scheme of the present application is as follows:

[0008] A rare earth synergistic thin type intumescent steel structure fireproof coating is prepared from the following raw material components by weight: modified polytertiary acetic acid emulsion 16-24 parts by weight, intumescent flame retardant 22-26 parts by weight, flaky cerium oxide 4-8 parts by weight, dihydrogen phosphate of rare earth 6-10 parts by weight, titanium white 4-8 parts by weight, kaolin 2-5 parts by weight, talc 2-5 parts by weight, long glass fiber 1-3 parts by weight, auxiliary agent 3-6 parts by weight, and pure water 21.5-24 parts by weight.

[0009] The solid content of the modified polytertiary acetic acid emulsion is 55%, and the pH value is 8-9.

[0010] The particle size of the flaky cerium oxide is 5-25 μm.

[0011] The particle size of the dihydrogen phosphate of rare earth is 10-40 μm, and the rare earth element is selected from lanthanum, cerium, praseodymium, neodymium, samarium, europium, and gadolinium.

[0012] In a preferred embodiment of the present application, the intumescent flame retardant is at least one of ammonium polyphosphate (APP), pentaerythritol (PER) / dipentaerythritol (DPER), and melamine (MEL).

[0013] Further preferably, the intumescent flame retardant is compounded from ammonium polyphosphate, pentaerythritol, and melamine in a mass ratio of 2:1:1.

[0014] In a preferred embodiment of the present application, the particle sizes of the kaolin, talc, and titanium white are all 10-30 μm.

[0015] In a preferred embodiment of the present application, the length of the long glass fiber is 10-20 mm, and the diameter is 10-20 μm.

[0016] In a preferred embodiment of the present application, the conductivity of the pure water is 5-10 µS / cm.

[0017] In a preferred embodiment of the present application, the intumescent flame retardant is compounded from ammonium polyphosphate, pentaerythritol, and melamine in a mass ratio of 2:1:1; the particle sizes of the kaolin and the talc are both 10-30 μm; the length of the long glass fiber is 10-20 mm, and the diameter is 10-20 μm; and the conductivity of the pure water is 5-10 µS / cm.

[0018] The preparation method of the rare earth synergistic thin type intumescent steel structure fireproof coating comprises the following steps:

[0019] (1) pure water and auxiliary agent are mixed and then dispersed at a high speed of 2000 r / min for 15 min;

[0020] (2) phosphorus acid dihydro rare earth, titanium white, kaolin and talcum powder are added into the material obtained in step (1) and dispersed at a high speed of 1500 r / min for 10 min; then glass beads are added and sand grinding is carried out until the fineness reaches 40 μm, and then filtration and weighing are carried out to obtain a filtrate;

[0021] (3) flaky cerium oxide is added into the filtrate obtained in step (2) and dispersed at a high speed of 3000 r / min for 20 min, and then intumescent flame retardant is added and dispersed at a high speed of 3000 r / min for 40 min;

[0022] (4) long glass fiber is added into the material obtained in step (3) and dispersed at a high speed of 3000 r / min for 20 min;

[0023] (5) the material obtained in step (4) is stirred while adding modified polyvinyl tertiary emulsion, the stirring speed is 1500 r / min, the stirring time is 10 min, and finally cooling and discharging are carried out to obtain the rare earth synergistic thin intumescent fireproof coating for steel structure.

[0024] The beneficial effects of the present application are:

[0025] 1. The present application ensures the strength of the carbon layer and improves the heat resistance of the carbon layer by the reaction with ammonium polyphosphate and the synergistic heat insulation effect of flaky cerium oxide, thereby enhancing the fireproof effect and achieving the performance requirements of the national standard.

[0026] 2. In a high temperature environment, the acid source ammonium polyphosphate in the intumescent flame retardant reacts with the added phosphorus acid dihydro rare earth to generate rare earth phosphate and phosphorus oxide, forming a carbon layer with higher strength and hardness, thereby improving the strength and density of the carbon layer and enhancing the fire retardant effect.

[0027] 3. The flaky cerium oxide is uniformly dispersed in the coating, and its barrier effect and high temperature resistance are utilized to help block the conduction of heat after the coating expands, improve the heat insulation performance of the carbon layer, and further enhance the fireproof effect.

[0028] 4. The preparation process of the present application is simple and convenient for construction, and can provide excellent fire protection for various steel structure buildings (such as railway stations, stadiums, shopping malls, workshops, etc.). BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 Pre-burning photos of the large plates treated with the fireproof coating of the present application example 3 and the comparative example 2.

[0030] Figure 2The photo of the large plate treated by the fireproof coating prepared in Example 3 after being burned at 1050℃.

[0031] Figure 3 The photo of the large plate treated by the fireproof coating prepared in Comparative Example 2 after being burned at 1050℃.

[0032] Figure 4 The photo of the burning process of the large plate treated by the fireproof coating prepared in Example 3.

[0033] Figure 5 The photo of the burning process of the large plate treated by the fireproof coating prepared in Comparative Example 2. DETAILED DESCRIPTION

[0034] The technical solutions of the present application are further described and explained in detail through specific embodiments combined with the accompanying drawings.

[0035] Example 1

[0036] (1) In a 1L iron tank container, first, 21.5g of pure water with an electrical conductivity of 8µS / cm was added; secondly, 6g of defoaming agent NXZ, dispersing agent Ucare 680U and alcohol ester C-12 were added respectively, and the mass ratio of NXZ, 680U and C-12 was 2:2:1; thirdly, the iron tank was placed in a high-speed disperser for dispersion, and the dispersion rate was 2000r / min and the dispersion time was 15min;

[0037] (2) In the iron tank in step (1), 6g of samarium dihydrogen phosphate with a particle size of 10μm (purchased from Jinshilang), 6g of titanium white powder with a particle size of 20μm, 5g of kaolin with a particle size of 10μm and 5g of talc powder with a particle size of 30μm were added respectively, and high-speed dispersion was carried out at 1500r / min for 10min; then 60% of the total amount of glass beads was added, sanding was carried out, the grinding fineness reached 40μm, and then filtration and weighing were carried out to obtain the filtrate;

[0038] (3) First, 6.5g of flaky cerium oxide with a particle size of 25μm (purchased from Jinshilang) was added to the filtrate obtained in step (2), and the dispersion was carried out at a dispersion speed of 3000r / min for 20min; then 26g of intumescent flame retardant (mass ratio APP:PER:MEL=2:1:1, and the purity of APP, PER and MEL is above 95%) was added, and high-speed dispersion was carried out, and the dispersion speed was 3000r / min and the dispersion time was 40min; after the dispersion was completed, an appropriate amount of pure water evaporated due to dispersion was added;

[0039] (4) 2 g of long glass fiber with a length of 10 mm and a diameter of 20 μm was added to the material obtained in step (3); then high-speed dispersion was performed at a dispersion speed of 3000 r / min for 20 min;

[0040] (5) 16 g of modified polyvinyl tertiary emulsion FR-168 (domestic, solid content of 55%, pH value of 8-9) was added to the material obtained in step (4) while stirring at a stirring speed of 1500 r / min for 10 min, and finally cooled and discharged to obtain a rare earth synergistic thin-type intumescent steel structure fireproof coating.

[0041] Example 2

[0042] (1) In a 1 L iron tank container, first, 24 g of pure water with an electrical conductivity of 5 µS / cm was added; secondly, 3 g of defoaming agent NXZ, dispersant Optic 680U and alcohol ester twelve C-12 were added respectively, and the mass ratio of NXZ, 680U and C-12 was 2:2:1; thirdly, the iron tank was placed in a high-speed dispersion machine for dispersion, and the dispersion rate was 2000 r / min and the dispersion time was 15 min;

[0043] (2) 8 g of cerous phosphate with a particle size of 30 μm (purchased from Jinshi Lanthanum), 8 g of titanium white powder with a particle size of 30 μm, 3 g of kaolin with a particle size of 30 μm and 3 g of talc powder with a particle size of 20 μm were added to the iron tank in step (1) respectively, and high-speed dispersion was performed at 1500 r / min for 10 min; then glass beads with a total amount of 60% were added, sanding was performed, the grinding fineness reached 40 μm, and then filtration and weighing were performed to obtain a filtrate;

[0044] (3) 8 g of flaky cerium oxide with a particle size of 5 μm (purchased from Jinshi Lanthanum) was first added to the filtrate obtained in step (2), and dispersed at a dispersion speed of 3000 r / min for 20 min; then 22 g of intumescent flame retardant (mass ratio of APP:PER:MEL=2:1:1, the purity of APP, PER and MEL is above 95%) was added and high-speed dispersion was performed at a dispersion speed of 3000 r / min for 40 min; after dispersion, an appropriate amount of pure water was added to make up for the evaporation caused by dispersion;

[0045] (4) 1 g of long glass fiber with a length of 20 mm and a diameter of 15 μm was added to the material obtained in step (3); then high-speed dispersion was performed at a dispersion speed of 3000 r / min for 20 min;

[0046] (5) In the material obtained in step (4), 20 g of modified polytertiary acetic emulsion FR-797 (imported, solid content 55%, pH value 8-9) is added while stirring, the stirring speed is 1500 r / min, the stirring time is 10 min, and finally cooling and discharging are performed to obtain the rare earth synergistic thin-type intumescent steel structure fireproof coating.

[0047] Example 3

[0048] (1) In a 1 L iron tank container, first, 22 g of pure water with an electrical conductivity of 10 µS / cm is added; secondly, 3.5 g of defoaming agent NXZ, dispersing agent Optic 680U and alcohol ester twelve C-12 are added respectively, and the mass ratio of NXZ, 680U and C-12 is 2:2:1; thirdly, the iron tank is placed in a high-speed disperser for dispersion, and the dispersion speed is 2000 r / min and the dispersion time is 15 min;

[0049] (2) In the iron tank in step (1), 10 g of lanthanum dihydrogen phosphate with a particle size of 40 µm (purchased from Jinshi Lanthanum), 4 g of titanium white powder with a particle size of 10 µm, 2 g of kaolin with a particle size of 20 µm and 2 g of talc powder with a particle size of 10 µm are added respectively, and high-speed dispersion is performed at 1500 r / min for 10 min; then, glass beads with a total amount of 60% are added, sanding is performed, the grinding fineness reaches 40 µm, and then filtration and weighing are performed to obtain a filtrate;

[0050] (3) First, 4 g of flaky cerium oxide with a particle size of 15 µm (purchased from Jinshi Lanthanum) is added to the filtrate obtained in step (2), and dispersion is performed at a dispersion speed of 3000 r / min for 20 min; then, 26 g of intumescent flame retardant (mass ratio APP:PER:MEL=2:1:1, the purity of APP, PER and MEL is above 95%) is added, high-speed dispersion is performed, the dispersion speed is 3000 r / min, and the dispersion time is 40 min; after the dispersion is completed, an appropriate amount of pure water is added to compensate for the evaporation caused by dispersion;

[0051] (4) In the material obtained in step (3), 2.5 g of long glass fiber with a length of 15 mm and a diameter of 10 µm is added; then, high-speed dispersion is performed, the dispersion speed is 3000 r / min, and the dispersion time is 20 min;

[0052] (5) In the material obtained in step (4), 24 g of modified polytertiary acetic emulsion FR-797 (imported, solid content 55%, pH value 8-9) is added while stirring, the stirring speed is 1500 r / min, the stirring time is 10 min, and finally cooling and discharging are performed to obtain the rare earth synergistic thin-type intumescent steel structure fireproof coating.

[0053] The rare earth synergistic thin-type intumescent steel structure fireproof coating prepared in this example is used to treat a large plate, and a combustion test is performed, and the results are as follows Figure 1a、 Figure 2 and Figure 4 as shown.

[0054] Comparative Example 1

[0055] (1) In a 1L iron tank container, first, 26g of pure water with conductivity of 10µS / cm was added; secondly, 3.5g of defoaming agent NXZ, dispersing agent Optic 680U and alcohol ester twelve C-12 were added respectively, wherein the mass ratio of NXZ, 680U and C-12 was 2:2:1; thirdly, the iron tank was placed in a high-speed disperser for dispersion, wherein the dispersion rate was 2000r / min and the dispersion time was 15min;

[0056] (2) In the iron tank in step (1), 10g of lanthanum dihydrogen phosphate with particle size of 40μm (purchased from Jinshilanthan), 4g of titanium white powder with particle size of 10μm, 2g of kaolin with particle size of 20μm and 2g of talc powder with particle size of 10μm were added respectively, and high-speed dispersion was carried out at 1500r / min for 10min; then 60% of the total amount of glass beads was added, sanding was carried out, the grinding fineness reached 40μm, and then filtration and weighing were carried out to obtain a filtrate;

[0057] (3) First, 0g of flaky cerium oxide was added to the filtrate obtained in step (2), and dispersion was carried out at a dispersion speed of 3000r / min for 20min; then 26g of intumescent flame retardant (mass ratio of APP:PER:MEL=2:1:1, the purity of APP, PER and MEL is above 95%) was added, and high-speed dispersion was carried out, the dispersion speed was 3000r / min, and the dispersion time was 40min; after dispersion, appropriate amount of pure water evaporated due to dispersion was added;

[0058] (4) 2.5g of long glass fiber with length of 15mm and diameter of 10μm was added to the material obtained in step (3); then high-speed dispersion was carried out, the dispersion speed was 3000r / min, and the dispersion time was 20min;

[0059] (5) In the material obtained in step (4), 24g of modified polyvinyl tertiary emulsion FR-797 (imported, solid content of 55%, pH value of 8-9) was added while stirring, the stirring speed was 1500r / min, the stirring time was 10min, and finally cooling and discharging were carried out to obtain a rare earth synergistic thin intumescent steel structure fireproof coating.

[0060] Comparative Example 2

[0061] (1) In a 1L iron tank container, first, 32g of pure water with conductivity of 10μS / cm was added; secondly, 3.5g of defoaming agent NXZ, dispersing agent Optic 680U and alcohol ester twelve C-12 were added respectively, wherein the mass ratio of NXZ, 680U and C-12 was 2:2:1; thirdly, the iron tank was placed in a high-speed disperser for dispersion, wherein the dispersion rate was 2000r / min and the dispersion time was 15min;

[0062] (2) In the iron tank in step (1), 0g of lanthanum dihydrogen phosphate (purchased from Jinshi Lanthanum), 4g of titanium white powder with particle size of 10μm, 2g of kaolin with particle size of 20μm and 2g of talc powder with particle size of 10μm were added respectively, and high-speed dispersion was carried out at 1500r / min for 10min; then, glass beads with a total amount of 60% were added, sanding was carried out, the grinding fineness reached 40μm, and then filtration and weighing were carried out to obtain a filtrate;

[0063] (3) First, 4g of flaky cerium oxide (purchased from Jinshi Lanthanum) with particle size of 15μm was added to the filtrate obtained in step (2), and dispersion was carried out at a dispersion speed of 3000r / min for 20min; then, 26g of intumescent flame retardant (mass ratio of APP:PER:MEL=2:1:1, the purity of APP, PER and MEL was above 95%) was added, and high-speed dispersion was carried out at a dispersion speed of 3000r / min for 40min; after dispersion, an appropriate amount of pure water evaporated due to dispersion was added;

[0064] (4) 2.5g of long glass fiber with length of 15mm and diameter of 10μm was added to the material obtained in step (3); then, high-speed dispersion was carried out at a dispersion speed of 3000r / min for 20min;

[0065] (5) 24g of modified polyvinyl tertiary emulsion FR-797 (imported, solid content was 55%, pH value was 8-9) was added to the material obtained in step (4) while stirring, the stirring speed was 1500r / min, and the stirring time was 10min; finally, cooling and discharging were carried out to obtain the fireproof coating.

[0066] The fireproof coating prepared by the present comparative example was used to treat a large plate, and the combustion test was carried out, and the results are shown in Figure 1 b、 Figure 3 and Figure 5 .

[0067] Comparative Example 3

[0068] (1) In a 1L iron tank container, first, 36g of pure water with conductivity of 10μS / cm was added; second, 3.5g of defoaming agent NXZ, dispersing agent Optic 680U and alcohol ester twelve C-12 were added respectively, wherein the mass ratio of NXZ, 680U and C-12 was 2:2:1; third, the iron tank was placed in a high-speed disperser for dispersion, wherein the dispersion rate was 2000r / min and the dispersion time was 15min;

[0069] (2) In the iron tank in step (1), 0g of lanthanum dihydrogen phosphate (purchased from Jinshi Lanthanum), 4g of titanium dioxide with particle size of 10μm, 2g of kaolin with particle size of 20μm and 2g of talc with particle size of 10μm were added respectively, and high-speed dispersion was carried out at 1500r / min for 10min; then, glass beads with a total amount of 60% were added, sand milling was carried out, the grinding fineness reached 40μm, and then filtration and weighing were carried out to obtain a filtrate;

[0070] (3) 0g of flaky cerium oxide (purchased from Jinshi Lanthanum) was first added to the filtrate obtained in step (2), and dispersion was carried out at a dispersion speed of 3000r / min for 20min; then, 26g of intumescent flame retardant (mass ratio of APP:PER:MEL=2:1:1, the purity of APP, PER and MEL is above 95%) was added, and high-speed dispersion was carried out, wherein the dispersion speed was 3000r / min and the dispersion time was 40min; after dispersion, an appropriate amount of pure water evaporated due to dispersion was added;

[0071] (4) 2.5g of long glass fiber with a length of 15mm and a diameter of 10μm was added to the material obtained in step (3); then, high-speed dispersion was carried out, wherein the dispersion speed was 3000r / min and the dispersion time was 20min;

[0072] (5) 24g of modified polyvinyl tertiary emulsion FR-797 (imported, solid content of 55%, pH value of 8-9) was added to the material obtained in step (4) while stirring, the stirring speed was 1500r / min, the stirring time was 10min, and finally cooling and discharging were carried out to obtain the fireproof coating.

[0073] The following are the performance test results of each example and comparative example:

[0074] Table 1 Performance test results of examples and comparative examples

[0075] Serial number Test item Index requirement Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 1 Drying time (surface dryness) / h ≤12 1.5 1.5 1.5 1.5 1.5 1.5 2 Initial drying anti-cracking property No crack should occur No crack No crack No crack No crack No crack No crack 3 Bonding strength / MPa ≥2.0 2.5 2.2 3.2 2.6 3.0 2.7 4 pH value ≥7 7.5 7.5 7.5 7.5 7.5 7.0 5 Moisture and heat resistance After 504h test, the coating should have no delamination, peeling phenomenon, and the attenuation of the heat insulation efficiency should be ≤35% Pass Pass Pass Pass Pass Fail 6 Salt spray corrosion resistance After 30 tests, the coating should have no blistering, significant deterioration, softening phenomenon, and the attenuation of the heat insulation efficiency should be ≤35% Pass Pass Pass Pass Fail Fail 7 Fire resistance (backboard temperature lower than 350℃) ≥120min (1000℃) 110 120 135 110 105 90 8 Coating thickness / μm 1000-3000 2.4 2.3 2.2 2.3 2.5 2.4 9 Swelling multiple ≥15 15.2 16 17 11 13 14

[0076] The above is only a preferred embodiment of the present application, and therefore cannot limit the scope of the present application, i.e. equivalent changes and modifications made according to the scope and content of the present patent should still be within the scope of the present application.

Claims

1. A rare earth-enhanced thin-film intumescent fireproof coating for steel structures, characterized in that: It is made from the following raw material components in parts by weight: 16-24 parts by weight of modified polyester emulsion FR-797, 22-26 parts by weight of intumescent flame retardant, 4-8 parts by weight of flake cerium oxide, 6-10 parts by weight of rare earth dihydrogen phosphate, 4-8 parts by weight of titanium dioxide, 2-5 parts by weight of kaolin, 2-5 parts by weight of talc, 1-3 parts by weight of long glass fiber, 3-6 parts by weight of additives, and 21.5-24 parts by weight of pure water; The modified polyester emulsion has a solid content of 55% and a pH value of 8-9. The particle size of the flaky cerium oxide is 5-25 μm; The particle size of rare earth dihydrogen phosphate is 10-40 μm, and the rare earth elements are selected from lanthanum, cerium, praseodymium, neodymium, samarium, europium and gadolinium; The intumescent flame retardant is a compound of ammonium polyphosphate, pentaerythritol and melamine in a mass ratio of 2:1:

1.

2. The rare earth-enhanced thin-film intumescent fireproof coating for steel structures as described in claim 1, characterized in that: The particle size of the kaolin, talc, and titanium dioxide is 10-30 μm.

3. The rare earth-enhanced thin-film intumescent fireproof coating for steel structures as described in claim 1, characterized in that: The long glass fiber has a length of 10-20 mm and a diameter of 10-20 μm.

4. The rare earth-enhanced thin-film intumescent fireproof coating for steel structures as described in claim 1, characterized in that: The conductivity of the pure water is 5-10 µS / cm.

5. The rare earth-enhanced thin-film intumescent fireproof coating for steel structures as described in claim 1, characterized in that: The intumescent flame retardant is composed of ammonium polyphosphate, pentaerythritol and melamine in a mass ratio of 2:1:1; the kaolin and talc have a particle size of 10-30 μm; the long glass fiber has a length of 10-20 mm and a diameter of 10-20 μm; and the pure water has a conductivity of 5-10 µS / cm.

6. A method for preparing a rare earth-enhanced thin-film intumescent fire-retardant coating for steel structures as described in any one of claims 1 to 5, characterized in that: Includes the following steps: (1) Mix pure water and additives and disperse at 2000 r / min for 15 min; (2) Add rare earth dihydrogen phosphate, titanium dioxide, kaolin and talc to the material obtained in step (1) and disperse at high speed of 1500 r / min for 10 min; then add glass microspheres and grind until the fineness reaches 40 μm, filter and weigh to obtain filtrate; (3) Add flake cerium oxide to the filtrate obtained in step (2), disperse at 3000 r / min for 20 min, then add intumescent flame retardant and disperse at 3000 r / min for 40 min. (4) Add long glass fibers to the material obtained in step (3) and disperse at 3000 r / min for 20 min; (5) Add modified polyester emulsion to the material obtained in step (4) while stirring. The stirring speed is 1500 r / min and the stirring time is 10 min. Finally, after cooling and discharge, the rare earth enhanced thin intumescent steel structure fireproof coating is obtained.

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