An intumescent fire-retardant coating for steel structures and its preparation method

Abstract

This invention belongs to the field of fire-retardant material application technology, and particularly relates to an intumescent fire-retardant coating for steel structures and its preparation method. This invention improves existing binders and fillers by using epoxy ester to modify acrylic acid, thereby increasing the stability and viscosity of the acrylic acid. Simultaneously, polyvinyl alcohol is used to further increase the viscosity of the acrylic acid. Furthermore, the properties of urea, which decomposes into melamine, ammonia, and carbon dioxide upon heating, are utilized to further supplement the gas source in the carbon-nitrogen-phosphorus expansion system. This allows the carbon source to expand better into a porous structure while increasing the release efficiency of flame-retardant gases, achieving further flame retardancy. Meanwhile, titanium dioxide composite hollow glass microspheres themselves have a strength-increasing effect, and the hydroxylated titanium dioxide composite hollow glass microspheres further lose water during the reaction process, thus better polymerizing with the carbon source to form a porous carbonaceous layer with good fire-retardant properties, effectively protecting the steel from fire damage.

Description

Technical Field

[0001] This invention belongs to the field of fireproof material application technology, and particularly relates to an intumescent fireproof coating for steel structures and its preparation method. Background Technology

[0002] Due to its high strength, good seismic performance, large spatial span, convenient construction, and short construction time, steel structure buildings have gradually become the mainstream of modern architecture and are widely used in large-span spatial structures and high-rise buildings.

[0003] Although steel is a non-combustible building material, its mechanical properties (elastic modulus, yield strength, tensile strength, etc.) decrease as the temperature rises under fire or high temperature. When the temperature exceeds 500℃, it will drop sharply, lose its original load-bearing capacity, and cause the steel building to collapse. Generally, the fire resistance limit of unprotected steel structures is about 15 minutes.

[0004] Currently, fire protection methods for steel structures include external cladding, water flushing, shielding, and fire-retardant coatings. Among these, spraying fire-retardant materials onto steel structures is a practical, convenient, and simple construction method. Based on fire protection principles, fire-retardant materials for steel structures can be divided into two types: non-intumescent and intumescent. Intumescent fire-retardant coatings, compared to non-intumescent types, have the advantages of higher construction efficiency, lower construction difficulty, and less environmental impact, and are therefore widely used. Improving the fire resistance of intumescent fire-retardant coatings is one of the current methods for improving them. Summary of the Invention

[0005] This invention provides an intumescent fire-retardant coating for steel structures with a reasonable formulation, simple preparation method, and effective ability to improve the fire resistance of intumescent fire-retardant coatings, as well as its preparation method.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The present invention provides an intumescent fireproof coating for steel structures, comprising the following components by weight:

[0007]

[0008]

[0009] The remainder is water. The binder is a mixture of epoxy ester modified waterborne acrylic acid, polyvinyl alcohol, and urea in a mass ratio of 7:1:2. The filler is a mixture of hydroxylated titanium dioxide composite glass hollow microspheres, porous ceramic powder, and inorganic mineral powder in a mass ratio of 1:1:2.

[0010] Preferably, the carbon-nitrogen-phosphorus expansion system is an expansion system with ammonium polyphosphate as the acid source, pentaerythritol as the carbon source, and melamine as the gas source.

[0011] Preferably, the mass ratio of ammonium polyphosphate, pentaerythritol, and melamine is 5:2:3.

[0012] Preferably, the inorganic mineral powder is at least one of montmorillonite powder, basalt powder, mica powder, vermiculite powder, and kaolin.

[0013] This invention also provides a method for preparing the above-mentioned intumescent fire-retardant coating for steel structures, comprising the following steps:

[0014] a. First, add titanium dioxide composite glass hollow microspheres to a mixed solution of sodium hydroxide and ethanol, heat under reflux for 12 hours, filter and dry to obtain hydroxylated titanium dioxide composite glass hollow microspheres for later use.

[0015] b. Then, dissolve urea in water, add epoxy ester modified waterborne acrylic acid and polyvinyl alcohol in sequence, stir for one hour to obtain the required adhesive, and set aside.

[0016] c. Next, after adding water to the carbon-nitrogen-phosphorus expansion system, ultrasonic treatment was carried out for 3 hours to obtain a suspension.

[0017] d. Then, add the defoamer, film-forming agent, thickener and dispersant to the suspension in sequence and stir for 1 hour in a water bath at 40°C;

[0018] e. After stirring is complete, add the binder to the suspension and continue stirring for 1 hour;

[0019] f. After stirring, the hydroxylated titanium dioxide composite glass hollow microspheres, porous ceramic powder, and inorganic mineral powder are mixed evenly and then added to the suspension. After stirring for 1 hour, the desired intumescent fireproof coating for steel structures is obtained.

[0020] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0021] 1. The intumescent fireproof coating for steel structures provided by this invention improves existing binders and fillers by modifying acrylic acid with epoxy ester, thereby enhancing the stability and viscosity of acrylic acid. Simultaneously, polyvinyl alcohol further increases the viscosity of acrylic acid. Furthermore, the properties of urea, which decomposes into melamine, ammonia, and carbon dioxide upon heating, further supplement the gas source in the carbon-nitrogen-phosphorus expansion system. This allows the carbon source to expand into a porous structure more effectively, while increasing the release efficiency of flame-retardant gases, thus achieving further flame retardancy. Additionally, the titanium dioxide composite hollow glass microspheres themselves have the function of increasing strength, and the hydroxylated titanium dioxide composite hollow glass microspheres further lose water during the reaction process, thereby better polymerizing with the carbon source to form a porous carbonaceous layer with good fire-retardant properties, effectively protecting steel from fire damage. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 The thermal insulation performance curve of the coating provided in Example 1;

[0024] Figure 2 The 1.5μm SEM image provided in Example 1;

[0025] Figure 3 The image is a 300nm SEM image provided in Example 1. Detailed Implementation

[0026] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0027] Numerous specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways than those described herein, and therefore the invention is not limited to the specific embodiments disclosed in the following specification.

[0028] Example 1: This example provides a method for preparing an intumescent fire-retardant coating for steel structures.

[0029] First, weigh out the following components according to weight: 8 parts of carbon-nitrogen-phosphorus expansion system (4 parts of ammonium polyphosphate, 1.6 parts of pentaerythritol, and 2.4 parts of melamine), 3.92 parts of epoxy ester modified waterborne acrylic acid, 0.56 parts of polyvinyl alcohol, 1.12 parts of urea, 0.4 parts of titanium dioxide composite glass hollow microspheres, 0.4 parts of porous ceramic powder, 0.8 parts of montmorillonite powder, 0.1 parts of defoamer (CS-300L), 0.5 parts of film-forming agent (RTC-12), 0.1 parts of thickener (TT-935), and 0.1 parts of dispersant (LP-91).

[0030] In the carbon-nitrogen-phosphorus expansion system, the acid source can be replaced with materials such as potassium ammonium polyphosphate, melamine phosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate. The carbon source can be materials such as pentaerythritol, sucrose, starch, and sorbitol. The gas source can be materials such as dicyandiamide, glycine, and chlorinated paraffin. However, considering the consistency of decomposition temperature, ammonium phosphate, pentaerythritol, and melamine are preferred. These three materials are also common materials in existing flame-retardant expansion systems. Therefore, they will not be described in this embodiment.

[0031] Considering that the main function of the filler is to improve the oxidation resistance of the carbon layer and enhance the strength of the coating, the addition of titanium dioxide composite glass hollow microspheres inherently possesses these properties. Furthermore, considering that the primary purpose of the carbon-nitrogen-phosphorus expansion reaction is heat absorption, as the heat increases, the hydroxylated titanium dioxide composite glass hollow microspheres will dehydrate. This dehydration facilitates their filling into the carbon layer, thereby forming a denser expanded carbon layer. Simultaneously, the addition of porous ceramic powder also aims to facilitate mutual filling between the filler and the carbon layer, further improving density. The addition of urea is mainly due to the fact that pore formation is related to gas. Urea's pyrolysis temperature is around 130℃, and its pyrolysis produces melamine, nitrogen, and carbon dioxide. Melamine itself is a gas source component, while nitrogen and carbon dioxide can form flame-retardant gases and dilute flammable gases such as oxygen. Thus, its initial pyrolysis reaction achieves a certain degree of heat absorption and flame retardancy while providing more gas source, which is beneficial for carbon pore formation.

[0032] Similarly, the quality of a coating is related to its physical and chemical properties such as adhesion, hiding power, hardness, elongation, water resistance, and weather resistance. Epoxy ester modified waterborne acrylic has better stability and adhesion than waterborne acrylic. The addition of polyvinyl alcohol further enhances its adhesion, thus providing better bonding.

[0033] In the preparation process, titanium dioxide composite hollow glass microspheres were first added to a mixed solution of sodium hydroxide and ethanol, heated under reflux for 12 hours, filtered, and dried to obtain hydroxylated titanium dioxide composite hollow glass microspheres for later use. Infrared spectroscopy revealed that the hydroxylated titanium dioxide composite hollow glass microspheres exhibited a high viscosity at 3300 cm⁻¹. -1 The enhanced vibrational peak of the OH group indicates successful hydroxylation preparation.

[0034] Then, after dissolving urea in water, epoxy ester-modified waterborne acrylic acid and polyvinyl alcohol are added sequentially and stirred for one hour to obtain the required binder for later use; next, the carbon-nitrogen-phosphorus expansion system is added to water and ultrasonically treated for 3 hours to obtain a suspension; then, defoamer, film-forming agent, thickener and dispersant are added sequentially to the suspension and stirred in a water bath at 40°C for 1 hour; after stirring is completed, the binder is added to the suspension and stirring is continued for 1 hour.

[0035] After stirring, the hydroxylated titanium dioxide composite hollow glass microspheres, porous ceramic powder, and inorganic mineral powder are mixed evenly and then added to the suspension. After stirring for 1 hour, the desired intumescent fireproof coating for steel structures is obtained. It should be noted that the water content should be between 26% and 42% of the total mass.

[0036] Performance testing: The basic performance of the coating was tested in accordance with the provisions of GB 14907—2018 "Fireproof Coatings for Steel Structures".

[0037] Samples: steel plates coated with the coating provided in Example 1, steel plates coated with steel structure fireproof coating with product number GJG03, and uncoated steel plates, all with the same thickness.

[0038] The results are as follows Figure 1 As shown, starting from time 0, the thermal insulation performance of the three samples increased with almost the same trend within 10 minutes. Afterward, the temperature on the back of the uncoated steel plate rose sharply. The steel plate coated with the steel structure fireproof coating (product number GJG03) approached 400°C within 60 minutes, while the coating provided in this embodiment remained below 300°C with a slow temperature increase within 60 minutes. Simultaneously, through... Figure 2 and Figure 3 The SEM images reveal that the carbon layer is filled with a large number of titanium dioxide composite glass hollow microspheres, making the entire structure dense.

[0039] Example 2: This example provides a method for preparing an intumescent fire-retardant coating for steel structures.

[0040] Weigh out the following components according to weight: 21 parts of carbon-nitrogen-phosphorus expansion system (10.5 parts of ammonium polyphosphate, 4.2 parts of pentaerythritol, and 6.3 parts of melamine), 10.29 parts of epoxy ester modified waterborne acrylic acid, 1.47 parts of polyvinyl alcohol, 2.94 parts of urea, 1.05 parts of titanium dioxide composite glass hollow microspheres, 1.05 parts of porous ceramic powder, 2.1 parts of montmorillonite powder, 0.3 parts of defoamer (CS-300L), 1 part of film-forming agent (RTC-12), 0.5 parts of thickener (TT-935), and 0.3 parts of dispersant (LP-91).

[0041] The preparation method is the same as in Example 1, and will not be described in detail here.

[0042] Example 3: This example provides a method for preparing an intumescent fire-retardant coating for steel structures.

[0043] Weigh out the following components according to weight: 15 parts of carbon-nitrogen-phosphorus expansion system (7.5 parts of ammonium polyphosphate, 3 parts of pentaerythritol, and 4.5 parts of melamine), 7.35 parts of epoxy ester modified waterborne acrylic acid, 1.05 parts of polyvinyl alcohol, 2.1 parts of urea, 0.26 parts of titanium dioxide composite glass hollow microspheres, 0.26 parts of porous ceramic powder, 5.2 parts of montmorillonite powder, 0.2 parts of defoamer (CS-300L), 0.7 parts of film-forming agent (RTC-12), 0.3 parts of thickener (TT-935), and 0.2 parts of dispersant (LP-91).

[0044] The preparation method is the same as in Example 1, and will not be described in detail here.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. An intumescent fire-retardant coating for steel structures, characterized in that, The ingredients are included in parts by weight as follows: 8 to 21 parts of the carbon-nitrogen-phosphorus expansion system; 5.6 to 14.7 parts of adhesive; Defoamer 0.1 to 0.3 parts; Film-forming agent: 0.5 to 1 part; Thickener 0.1 to 0.5 parts; Dispersant: 0.1 to 0.3 parts; 1.6 to 4.2 parts of filler; The remainder is water. The binder is a mixture of epoxy ester modified waterborne acrylic acid, polyvinyl alcohol, and urea in a mass ratio of 7:1:

2. The filler is a mixture of hydroxylated titanium dioxide composite glass hollow microspheres, porous ceramic powder, and inorganic mineral powder in a mass ratio of 1:1:

2. The film-forming agent is RTC-12. The water accounts for 26% to 42% of the total mass. The carbon-nitrogen-phosphorus expansion system is an expansion system with ammonium polyphosphate as the acid source, pentaerythritol as the carbon source, and melamine as the gas source.

2. The intumescent fire-retardant coating for steel structure according to claim 1, characterized in that, The mass ratio of ammonium polyphosphate, pentaerythritol, and melamine is 5:2:

3.

3. The intumescent fire-retardant coating for steel structure according to claim 1, characterized in that, The inorganic mineral powder is at least one of montmorillonite powder, basalt powder, mica powder, vermiculite powder, and kaolin.

4. Process for the preparation of a fireproofing coating for expanded steel structures according to any of the preceding claims 1 to 3, characterized in that, Includes the following steps: a. First, add titanium dioxide composite glass hollow microspheres to a mixed solution of sodium hydroxide and ethanol, heat under reflux for 12 hours, filter and dry to obtain hydroxylated titanium dioxide composite glass hollow microspheres for later use. b. Then, dissolve urea in water, add epoxy ester modified waterborne acrylic acid and polyvinyl alcohol in sequence, stir for one hour to obtain the required adhesive, and set aside. c. Next, after adding water to the carbon-nitrogen-phosphorus expansion system, ultrasonic treatment was carried out for 3 hours to obtain a suspension. d. Then, add the defoamer, film-forming agent, thickener and dispersant to the suspension in sequence and stir in a water bath at 40 °C for 1 hour; e. After stirring is complete, add the binder to the suspension and continue stirring for 1 hour; f. After stirring, the hydroxylated titanium dioxide composite glass hollow microspheres, porous ceramic powder, and inorganic mineral powder are mixed evenly and then added to the suspension. After stirring for 1 hour, the desired intumescent steel structure fireproof coating is obtained.

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