Alkali-resistant fire-resistant coating for buildings, and preparation method and application thereof

Abstract

This invention discloses an alkali-resistant and fire-resistant coating for building applications, its preparation method, and its application. The material is composed of the following raw materials in parts by weight: 20-60 parts aluminum tripolyphosphate, 20-40 parts water glass, 10-20 parts silica, 5-10 parts alumina, 1-5 parts kaolin, 1-5 parts zirconium oxide, 1-5 parts anhydrous calcium sulfate, 5-40 parts modifier, 2-8 parts binder, 1-2 parts curing agent, and 1-2 parts defoamer. The preparation method involves mixing aluminum tripolyphosphate and the modifier in a ball mill for 10-120 minutes to obtain modified aluminum tripolyphosphate; ball milling with alcohol and water as wet milling liquid for 60-720 minutes at a milling rate of 100-800 r / min; drying the mixture for 36-48 hours; then placing the other raw materials and the modified aluminum tripolyphosphate powder into a beaker, adding water glass solution, and stirring on a magnetic stirrer to obtain the target alkali-resistant and fire-resistant coating. The alkali-resistant and fire-resistant coating for building applications of this invention has excellent alkali resistance, good mechanical properties and fire resistance and flame retardancy, and the preparation process is simple and suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of composite material coating technology, specifically relating to an alkali-resistant and fire-resistant coating for building, its preparation method, and its application. Background Technology

[0002] In industrial plants and chemical storage warehouses that use strong alkalis as raw materials or produce strong alkalis, strong alkalis can react chemically with many building materials, especially cement. When building materials are exposed to strong alkali environments for a long time or when accidents such as chemical leaks and fires occur, there is a phenomenon of corrosion of building materials. Therefore, relevant working environments (such as industrial plants and chemical storage warehouses) need alkali-resistant anti-corrosion coatings to protect building walls and cement walls from corrosion by special industrial environments, thereby affecting building safety.

[0003] Anti-corrosion coatings are continuous, firmly adhered coatings applied to the surface of materials, isolating the material from surrounding media (such as moisture, water, chemical atmospheres, electrolytes, organic solvents, acids, alkalis, etc.) and preventing or mitigating chemical and electrochemical interactions with these media. Existing alkali-resistant coatings mainly suffer from the following problems:

[0004] (1) Existing alkali-resistant coatings are all based on organic materials. During long-term use, they face serious aging problems, and the protective effect gradually decreases, causing the coating to blister, crack, or even peel off, resulting in the coating losing its protective function and thus material failure, which greatly reduces the actual service life.

[0005] (2) Since the structure of organic matter is mainly carbon-oxygen bonds and carbon-hydrogen bonds, when encountering accidents such as fire, alkali-resistant coatings with organic matter as the main material will burn and fuel the fire, posing a great safety hazard in terms of fire prevention.

[0006] (3) Existing alkali-resistant coatings often contain heavy metals such as red lead and zinc chromate yellow, which are not environmentally friendly. At present, they face great challenges in terms of environmental protection. Water-based, high-solids, and solvent-free anti-corrosion coatings are the development trends of green and environmentally friendly anti-corrosion coatings.

[0007] Therefore, the market urgently needs new alkali-resistant and fire-resistant coatings with inorganic solid phase as the main material. Summary of the Invention

[0008] The first objective of this invention is to provide an alkali-resistant and fire-resistant coating for building applications, and the second objective of this invention is to provide a method for preparing and applying the alkali-resistant and fire-resistant coating for building applications.

[0009] The first objective of this invention is achieved as follows: an alkali-resistant and fire-resistant coating for building applications, comprising the following raw materials in parts by weight: 20-60 parts aluminum tripolyphosphate, 20-40 parts water glass, 10-20 parts silica, 5-10 parts alumina, 1-5 parts kaolin, 1-5 parts zirconium oxide, 1-5 parts anhydrous calcium sulfate, 5-40 parts modifier, 2-8 parts binder, 1-2 parts curing agent, and 1-2 parts defoamer.

[0010] The second objective of this invention is achieved by the following steps in the preparation method of the alkali-resistant and fire-resistant coating for building:

[0011] 1) Mix aluminum tripolyphosphate and a modifier in a ball mill for 10-120 min to obtain modified aluminum tripolyphosphate; ball mill with alcohol and water as wet milling liquid for 60-720 min at a ball milling rate of 100-800 r / min, and then dry for 36-48 h.

[0012] 2) Place silica, alumina, kaolin, zirconium oxide, anhydrous calcium sulfate, binder, curing agent, defoamer and the modified aluminum tripolyphosphate powder described in step 1 into a beaker, add water glass solution, place on a magnetic stirrer for stirring, and adjust the viscosity to obtain the target coating.

[0013] The application of the alkali-resistant and fire-resistant coating for building is in the preparation of surface coatings for buildings. The specific application method is to grind and clean the surface of the building material, and then apply the alkali-resistant and fire-resistant coating for building evenly to the surface of the building material by spraying or brushing, with a coating thickness of 0.5~10mm.

[0014] The beneficial effects of this invention are as follows:

[0015] 1. This invention provides an alkali-resistant and fire-resistant coating for building applications, using aluminum tripolyphosphate as one of the main raw materials. Aluminum tripolyphosphate is an inorganic solid phase that is non-combustible and can undergo a certain degree of ceramization at high temperatures, providing better fire and high-temperature resistance. It has good film-forming properties with resin materials, forming a dense protective film with excellent alkali resistance. Its density is much lower than that of heavy metal anti-rust pigments such as red lead and zinc chromate yellow commonly added to existing alkali-resistant coatings, resulting in less material usage in production. This invention, based on practical applications, mixes various inorganic materials in a certain proportion and adds a very small amount of resin materials, resulting in excellent alkali and fire resistance, and a simple preparation process. Furthermore, the raw materials used are widely available, have low density, require small amounts, and are environmentally friendly, making them suitable for industrial production.

[0016] 2. The alkali-resistant and fire-resistant coating for building prepared by this invention has excellent alkali resistance, as well as good mechanical properties and fire resistance and flame-retardant properties: it has almost no weight loss after being soaked in a 15% sodium hydroxide solution for 7-15 days, and can achieve long-term protection in alkaline environment; a 1cm thick coating material will not be ignited when burned for ten minutes in a gas cylinder (flame temperature 600~1300°C).

[0017] 3. In addition to its reliable performance and wide range of applications, the alkali-resistant and fire-resistant coating for building of this invention is simple to use. After being applied to the surface of building materials (building walls and cement walls), it can be naturally cured at room temperature for 24 to 48 hours to meet the requirements for use. Attached Figure Description

[0018] Figure 1 The diagram shows the alkali resistance test results of the alkali-resistant coating prepared in Example 5.

[0019] Figure 2 The image shows the fire impact test results of the alkali-resistant coating prepared in Example 5.

[0020] Figure 3 The back temperature curve of the fire resistance test of the alkali-resistant coating prepared in Example 5;

[0021] Figure 4 The weight change curve of the alkali resistance test for the alkali-resistant coating prepared in Example 5 is shown.

[0022] Figure 5 The heat release rate change curve of the alkali-resistant coating prepared in Example 5 is shown in the fire resistance test.

[0023] Figure 6 The images show the alkali resistance test results of the coating prepared in Comparative Example 1. (a) is a picture of the alkali resistance test of the coating in Comparative Example 1 after 24 hours, and (b) is a picture of the alkali resistance test of the coating in Comparative Example 1 after 48 hours.

[0024] Figure 7 The image shows the nanoindentation Young's modulus mechanical properties of the alkali-resistant coating prepared in Example 5.

[0025] Figure 8 The tensile strength results are for the alkali-resistant coating prepared in Example 5. Detailed Implementation

[0026] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0027] This invention discloses an alkali-resistant and fire-resistant coating for building applications, which is composed of the following raw materials in parts by weight: 20-60 parts aluminum tripolyphosphate, 20-40 parts water glass, 10-20 parts silica, 5-10 parts alumina, 1-5 parts kaolin, 1-5 parts zirconium oxide, 1-5 parts anhydrous calcium sulfate, 5-40 parts modifier, 2-8 parts binder, 1-2 parts curing agent, and 1-2 parts defoamer.

[0028] The modulus of the water glass is 2.6 to 3.7, and the particle size of the silicon dioxide, alumina, kaolin, zirconium oxide, and anhydrous calcium sulfate is 250 mesh to 500 mesh.

[0029] The modifier is composed of zinc oxide, calcium oxide, or magnesium oxide with a particle size of 250-500 mesh.

[0030] The adhesive is epoxy resin, phenolic resin, or 0.1-20% polyvinyl alcohol.

[0031] The curing agent is phthalic anhydride, 4 ， 4-Diaminodiphenylmethane or 0.1-5% ethylenediamine.

[0032] The defoamer is polydimethylsiloxane or 0.05-1% of a polyether-type defoamer.

[0033] This invention also provides a method for preparing the aforementioned alkali-resistant and fire-resistant coating for building, which is implemented according to the following steps:

[0034] 1) Mix aluminum tripolyphosphate and a modifier in a ball mill for 10-120 min to obtain modified aluminum tripolyphosphate; ball mill with alcohol and water as wet milling liquid for 60-720 min at a ball milling rate of 100-800 r / min, and then dry for 36-48 h.

[0035] 2) Place silica, alumina, kaolin, zirconium oxide, anhydrous calcium sulfate, binder, curing agent, defoamer and the modified aluminum tripolyphosphate powder described in step 1 into a beaker, add water glass solution, place on a magnetic stirrer for stirring, and adjust the viscosity to obtain the target coating.

[0036] In step 2), the magnetic stirring time is 20~400min and the stirring speed is 100~700r / min.

[0037] The present invention further provides the application of the alkali-resistant and fire-resistant coating for building in the preparation of building surface coatings. The specific coating method is to grind and clean the surface of the building material, and then uniformly apply the alkali-resistant and fire-resistant coating for building to the surface of the building material by spraying or brushing, with a coating thickness of 0.5~10mm.

[0038] The spraying process mainly involves connecting a spray bottle to an air compressor, using strong air pressure to spray the alkali-resistant and fire-resistant coating for building onto the steel substrate. The spraying rate of the spray bottle is 0.3~6L / min, and the spraying distance between the spray bottle and the metal is 10cm~80cm.

[0039] Example 1

[0040] An alkali-resistant and fire-resistant coating for building applications is composed of the following raw materials in parts by weight: 40 parts modified aluminum tripolyphosphate, 25 parts water glass, 10 parts silica, 5 parts alumina, 3 parts kaolin, 2 parts zirconium oxide, 3 parts anhydrous calcium sulfate, 3 parts epoxy resin, 0.86 parts phthalic anhydride, and 1 part polydimethylsiloxane defoamer.

[0041] The preparation method of modified aluminum tripolyphosphate is as follows: 25g aluminum tripolyphosphate, 5g zinc oxide, 10g calcium oxide and 5g magnesium oxide are put into a ball mill and mixed at 300r / min for 120min. Then alcohol is added as the ball milling medium and the mixture is ball milled at 300r / min for 600min. Then water is used as the ball milling medium and the mixture is ball milled at 300r / min for 120min. After drying, the modified aluminum tripolyphosphate is obtained by sieving through a 200-mesh sieve.

[0042] Example 2

[0043] An alkali-resistant and fire-resistant coating for construction is composed of the following raw materials in parts by weight: 60 parts modified aluminum tripolyphosphate, 40 parts water glass, 10 parts silica, 10 parts alumina, 5 parts kaolin, 1 part zirconium oxide, 1 part anhydrous calcium sulfate, 8 parts phenolic resin, and 4 parts [other components not specified in the original text]. ， 0.75 parts of 4-diaminodiphenylmethane and 1-2 parts of polydimethylsiloxane.

[0044] The preparation method of modified aluminum tripolyphosphate is as follows: 25g of aluminum tripolyphosphate, 10g of zinc oxide, 5g of calcium oxide and 5g of magnesium oxide are put into a ball mill and mixed at 300r / min for 120min. Then, alcohol is added as the ball milling medium and the mixture is ball milled at 300r / min for 600min. Then, water is used as the ball milling medium and the mixture is ball milled at 300r / min for 120min. After drying, the modified aluminum tripolyphosphate is obtained by sieving through a 200-mesh sieve.

[0045] Example 3

[0046] An alkali-resistant and fire-resistant coating for building applications is composed of the following raw materials in parts by weight: 20 parts modified aluminum tripolyphosphate, 20 parts water glass, 20 parts silica, 5 parts alumina, 1 part kaolin, 5 parts zirconium oxide, 5 parts anhydrous calcium sulfate, 2 parts 0.1% polyvinyl alcohol, 1.05 parts 0.1% ethylenediamine, and 1-2 parts 0.05% polyether defoamer.

[0047] The preparation method of modified aluminum tripolyphosphate is as follows: 25g aluminum tripolyphosphate, 5g zinc oxide, 5g calcium oxide and 5g magnesium oxide are put into a ball mill and mixed at 300r / min for 120min. Then alcohol is added as the ball milling medium and the mixture is ball milled at 300r / min for 600min. Then water is used as the ball milling medium and the mixture is ball milled at 300r / min for 120min. After drying, the modified aluminum tripolyphosphate is obtained by sieving through a 200-mesh sieve.

[0048] Example 4

[0049] An alkali-resistant and fire-resistant coating for building applications is composed of the following raw materials in parts by weight: 30 parts modified aluminum tripolyphosphate, 30 parts water glass, 15 parts silica, 8 parts alumina, 4 parts kaolin, 3 parts zirconium oxide, 4 parts anhydrous calcium sulfate, 4 parts 20% polyvinyl alcohol, 0.75-1.05 parts 5% ethylenediamine, and 1-2 parts 1% polyether-type defoamer.

[0050] Example 5

[0051] According to the formulation of Example 1, sieved modified aluminum tripolyphosphate was weighed and added to water glass, silica, alumina, kaolin, and zirconium oxide. Stirring was initiated at 600 r / min using a magnetic stirrer. After stirring for 20 minutes, anhydrous calcium sulfate was added and stirring continued to obtain a solid matrix. The binder, curing agent, and defoamer were then mixed thoroughly and added to the solid matrix. Stirring continued until fully incorporated to obtain an alkali-resistant fire-retardant coating.

[0052] After cleaning the building wall surface, use a high-pressure air gun to blow away surface impurities. Connect the spray bottle to the vacuum pump and spray the anti-oxidation coating evenly onto the building material surface. The spraying rate is 1 L / min, the spraying distance between the spray bottle and the metal is 20 cm, and the coating thickness is 1 mm. After curing at room temperature for 36 hours, an alkali-resistant and fire-retardant coating is obtained.

[0053] The spraying of the alkali-resistant fireproof coating was changed to brushing. The specific method is as follows: use a brush to apply the alkali-resistant fireproof coating to the surface of the building material. After brushing, use the brush again to repair the areas on the surface of the building material that were not brushed. The thickness of the coating is 1 mm. After curing at room temperature for 36 hours, the alkali-resistant fireproof coating is obtained.

[0054] Example 6

[0055] According to the formulation of Example 1, sieved modified aluminum tripolyphosphate was weighed and added to water glass, silica, alumina, kaolin, and zirconium oxide. Stirring was initiated at 400 r / min using a magnetic stirrer. After stirring for 100 min, anhydrous calcium sulfate was added and stirring continued to obtain a solid matrix. The binder, curing agent, and defoamer were then mixed evenly and added to the prepared solid matrix. Stirring continued until fully incorporated to obtain an alkali-resistant fire-retardant coating.

[0056] After cleaning the building wall surface, use a high-pressure air gun to blow away surface impurities. Connect the spray bottle to the vacuum pump and spray the anti-oxidation coating evenly onto the metal surface. The spraying rate is 0.3 L / min, the spraying distance between the spray bottle and the metal is 10 cm, and the coating thickness is 10 mm. After curing at room temperature for 48 hours, an alkali-resistant and fire-retardant coating is obtained.

[0057] The spraying of the alkali-resistant fireproof coating was changed to brushing. The specific method is as follows: use a brush to apply the alkali-resistant fireproof coating to the surface of the building material. After brushing, use the brush again to repair the areas on the surface of the building material that were not brushed. The thickness of the coating is 10 mm. After curing at room temperature for 48 hours, the alkali-resistant fireproof coating material is obtained.

[0058] Example 7

[0059] According to the formulation in Example 2, sieved modified aluminum tripolyphosphate was weighed and added to water glass, silica, alumina, kaolin, and zirconium oxide. Stirring was then initiated at 100 r / min using a magnetic stirrer. After stirring for 700 min, anhydrous calcium sulfate was added and stirring continued to obtain a solid matrix. The binder, curing agent, and defoamer were then mixed thoroughly and added to the solid matrix. Stirring continued until fully incorporated to obtain an alkali-resistant fire-retardant coating.

[0060] After cleaning the building wall surface, use a high-pressure air gun to blow away surface impurities. Connect the spray bottle to the vacuum pump and evenly spray the anti-oxidation coating onto the building material surface. The spraying rate is 6L / min, the spraying distance between the spray bottle and the building material surface is 80cm, and the coating thickness is 0.5mm. After curing at room temperature for 24 hours, an alkali-resistant and fire-retardant coating is obtained.

[0061] The spraying of the alkali-resistant fireproof coating was changed to brushing. The specific method is as follows: use a brush to apply the alkali-resistant fireproof coating to the surface of the building material. After brushing, use the brush again to repair the areas on the surface of the building material that were not brushed. The thickness of the coating is 0.5 mm. After curing at room temperature for 24 hours, the alkali-resistant fireproof coating material is obtained.

[0062] The coatings prepared in Examples 5-7 showed no discoloration or blistering after curing.

[0063] Comparative Example 1

[0064] An alkali-resistant and fire-resistant coating for building applications is composed of the following raw materials in parts by weight: 25 parts water glass, 10 parts silica, 5 parts alumina, 3 parts kaolin, 2 parts zirconium oxide, 3 parts anhydrous calcium sulfate, 3 parts epoxy resin, 0.86 parts phthalic anhydride, and 1 part polydimethylsiloxane defoamer.

[0065] Preparation method: Water glass, silica, alumina, kaolin, and zirconium oxide are mixed and stirred at 400 r / min using a magnetic stirrer. After stirring for 100 min, anhydrous calcium sulfate is added and stirring is continued to obtain a solid matrix. The binder, curing agent, and defoamer are mixed evenly and then added to the mixed solid matrix. Stirring is continued until fully incorporated to obtain an alkali-resistant fireproof coating.

[0066] Comparative Example 2

[0067] The following ingredients were added: 20 parts of modified aluminum tripolyphosphate, 25 parts of water glass, 10 parts of silica, 5 parts of alumina, 3 parts of kaolin, 2 parts of zirconium oxide, 3 parts of anhydrous calcium sulfate, 3 parts of epoxy resin, 0.86 parts of phthalic anhydride, and 1 part of polydimethylsiloxane defoamer.

[0068] The preparation method of modified aluminum tripolyphosphate is as follows: 15g of aluminum tripolyphosphate, 30g of calcium oxide, and 15g of magnesium oxide are put into a ball mill and mixed at 300r / min for 120min. Then, alcohol is added as the ball milling medium and the mixture is ball milled at 300r / min for 600min. Finally, water is used as the ball milling medium and the mixture is ball milled at 300r / min for 120min. After drying, the modified aluminum tripolyphosphate is obtained by sieving through a 200-mesh sieve.

[0069] Weigh the sieved modified aluminum tripolyphosphate, add water glass, silica, alumina, kaolin, and zirconium oxide, and begin stirring. Use a magnetic stirrer at 400 r / min and stir for 100 min. Then add anhydrous calcium sulfate and continue stirring to obtain a solid matrix. Mix the binder, curing agent, and defoamer thoroughly, then add them to the solid matrix and continue stirring until fully combined to obtain an alkali-resistant fire-retardant coating.

[0070] Comparative Example 3

[0071] Similar to Comparative Example 2, the modified aluminum tripolyphosphate modification scheme was changed as follows: 25g of aluminum tripolyphosphate and 5g of zinc oxide were placed in a ball mill and mixed at 300r / min for 120min. Then, alcohol was added as the ball milling medium and the mixture was ball milled at 300r / min for 600min. Finally, water was used as the ball milling medium and the mixture was ball milled at 300r / min for 120min. After drying, the modified aluminum tripolyphosphate was obtained by sieving through a 200-mesh sieve.

[0072] Weigh the sieved modified aluminum tripolyphosphate, add water glass, silica, alumina, kaolin, and zirconium oxide, and begin stirring. Use a magnetic stirrer at 400 r / min and stir for 100 min. Then add anhydrous calcium sulfate and continue stirring to obtain a solid matrix. Mix the binder, curing agent, and defoamer thoroughly, then add them to the solid matrix and continue stirring until fully combined to obtain an alkali-resistant fire-retardant coating.

[0073] Test Example 1: Alkali resistance test of the coating prepared in Example 5

[0074] The coatings prepared using the methods of Example 5 and Comparative Examples 1-3 were respectively applied to the surface of a 100*100*5mm steel plate with a thickness of 5mm. After the coatings cured, the steel plates were immersed in a 15% sodium hydroxide solution for 15 days and then weighed. Figure 1 ).

[0075] Result: As Figure 4 As shown, the coating prepared in Example 5 showed virtually no weight loss after immersion in a 15% sodium hydroxide solution for 15 days, with no discoloration or blistering, indicating that it can achieve long-term protection in an alkaline environment. In contrast, the coating prepared in Comparative Example 1 showed a weight loss of over 30% after 48 hours of alkali resistance testing, and cracks began to appear after 24 hours, completely failing after 48 hours. Figure 6 Testing revealed that the coating prepared in Comparative Example 2 failed after 5 days, while the coating prepared in Comparative Example 3 failed after 3 days. This demonstrates that the coating prepared in this invention possesses excellent alkali resistance.

[0076] Test Example 2: Fire resistance test of the coating prepared in Example 5

[0077] The coating prepared in Example 5 was applied to the surface of a 100*100*5mm steel plate and sprayed to a thickness of 5mm. After the coating cured, it was burned with gas (flame temperature 600~1300°C) at a distance of 10cm for 10-30 minutes. Figure 2 The test measures parameters such as the temperature on the back of the steel plate and the HRR (heat release rate) during combustion.

[0078] Result: After testing, as shown... Figure 3 As shown, the coating prepared by this invention will not ignite after burning for ten minutes.

[0079] As can be seen from the figure, the back temperature tends to stabilize after 200℃. During the 30-minute test, the coating was not ignited because the back temperature remained within a certain range and was far below the flame temperature.

[0080] from Figure 5 It can be seen that the peak heat release rate of the coating prepared by this invention is only 400 (KW / m). 2Around 800-1500 (KW / m³) compared to the peak heat release rate of pure resin. 2 The heat release, including the peak value of the heat release, is significantly reduced, indicating that the coating of the present invention has a certain degree of fire resistance.

[0081] Experimental Example 3: Mechanical property testing of the coating prepared in Example 5

[0082] Testing showed that the Young's modulus of the coating prepared in Example 5 was between 1.8 and 26 GPa. Figure 7 The modulus of the resin material is greater than that of the Young's modulus (1-5 GPa), indicating that the coating prepared by the present invention ensures the bonding strength of the material itself by adding resin materials.

[0083] The coating prepared in Example 5 was subjected to a tensile test, and the results showed that ( Figure 8 It reaches its maximum tensile strength of 45.58 MPa at 6.09% strain, which is slightly lower than the 52.30 MPa reached by pure epoxy resin at 10.52% strain, but still has good mechanical properties to ensure the bonding strength and mechanical properties of the coating during service.

Claims

1. An alkali-resistant and fire-resistant coating for building applications, characterized in that, The product, by weight, is composed of 20-60 parts modified aluminum tripolyphosphate powder, 20-40 parts water glass, 10-20 parts silica, 5-10 parts alumina, 1-5 parts kaolin, 1-5 parts zirconium oxide, 1-5 parts anhydrous calcium sulfate, 2-8 parts binder, 0.75-1.05 parts curing agent, and 1-2 parts defoamer. The modified aluminum tripolyphosphate is made of aluminum tripolyphosphate and a modifier, which consists of zinc oxide, calcium oxide, and magnesium oxide with a particle size of 250-500 mesh. The weight ratio of aluminum tripolyphosphate to zinc oxide, calcium oxide, and magnesium oxide is 10:2-4:2-4:

2.

2. The alkali-resistant and fire-resistant coating for building applications according to claim 1, characterized in that, The modulus of the water glass is 2.6 to 3.7, and the particle size of the silicon dioxide, alumina, kaolin, zirconium oxide, and anhydrous calcium sulfate is 250 to 500 mesh.

3. The alkali-resistant and fire-resistant coating for building applications according to claim 1, characterized in that, The adhesive is epoxy resin, phenolic resin, or 0.1-20% polyvinyl alcohol.

4. The alkali-resistant and fire-resistant coating for building applications according to claim 1, characterized in that, The curing agent is phthalic anhydride, 4,4-diaminodiphenylmethane, or 0.1-5% ethylenediamine.

5. The alkali-resistant and fire-resistant coating for building applications according to claim 1, characterized in that, The defoamer is polydimethylsiloxane and / or 0.05-1% of a polyether-type defoamer.

6. A method for preparing the alkali-resistant and fire-resistant coating for building as described in claim 1, characterized in that, Follow these steps to achieve the following: 1) Mix aluminum tripolyphosphate and the modifier in a ball mill at 300 r / min for 120 min, then add alcohol as the ball milling medium and ball mill at 300 r / min for 600 min, then use water as the ball milling medium and ball mill at 300 r / min for 120 min. After drying, sieve through a 200 mesh screen to obtain modified aluminum tripolyphosphate powder. 2) Weigh the modified aluminum tripolyphosphate powder and add water glass, silica, alumina, kaolin, and zirconium oxide. Stir magnetically at 400-600 r / min for 20-100 min, then add anhydrous calcium sulfate and continue stirring to obtain a solid matrix. Mix the binder, curing agent, and defoamer evenly and add them to the solid matrix. Continue stirring until fully fused to obtain an alkali-resistant fireproof coating.

7. The application of the alkali-resistant and fire-resistant coating for building as described in claim 1 in the preparation of building surface coatings, characterized in that, The coating method involves grinding and cleaning the surface of the building material, and then uniformly applying the alkali-resistant and fire-resistant coating for building to the surface of the building material by spraying or brushing, with a coating thickness of 0.5~10mm.

8. The application according to claim 7, characterized in that, Spraying involves connecting a spray bottle to an air compressor, using strong air pressure to spray the alkali-resistant and fire-resistant coating for building onto a steel substrate. The spraying rate of the spray bottle is 0.3~6L / min, and the spraying distance between the spray bottle and the metal is 10cm~80cm.

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