A method for preparing an environmentally friendly intumescent fire-retardant coating for steel structures made of carbon, nitrogen, sulfur, and silicon.

Abstract

The invention discloses a method for preparing a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating, which is characterized by comprising the following steps: mixing water, urea and gypsum with a ball mill, adding a stabilizer and stirring to obtain a urea-gypsum slurry; taking raw materials of water, urea, formaldehyde, hydroxyethyl cellulose aqueous solution, hydrogen peroxide, defoamer, and hydrochloric acid and sodium hydroxide aqueous solution, and performing polymerization reaction to obtain a urea-formaldehyde resin; adding water, a dispersant, a defoamer, a film-forming aid, a preservative, a urea-gypsum slurry, and a urea-formaldehyde resin into a mixer and stirring evenly, then adding starch, vermiculite powder, graphite, and aluminum silicate refractory powder until evenly dispersed, adding acrylic emulsion and a thickener and stirring and dispersing evenly, and thus obtaining a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating. The carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating prepared by the invention can improve construction performance, coating water resistance and fire resistance, improve environmental protection performance, and has strong practicality.

Description

Technical Field

[0001] The present invention belongs to the preparation of steel structure fire retardant coating, and relates to a preparation method of carbon nitrogen sulfur silicon environmentally friendly steel structure intumescent fire retardant coating. The carbon nitrogen sulfur silicon environmentally friendly steel structure intumescent fire retardant coating prepared by the present invention is particularly suitable for use as a fire retardant coating for steel structures. Background Art

[0002] At present, the most direct, effective and low-cost measure for steel structure fire prevention is to coat the surface of the steel structure with water-based fire retardant coating. The fire retardant coating can block the transfer of heat to the steel surface and increase the fire resistance time of the steel structure when heated, thereby achieving a fire prevention effect.

[0003] In the prior art, fire retardant coatings for steel structures are mainly composed of binders, fire retardant systems, pigments, fillers and other additives. Binders, also known as film formers, are the base materials of intumescent fire retardant coatings. In addition to being able to evenly disperse the intumescent flame retardant system and fillers to bond the coating as a whole, they can also participate in the carbonization process of the coating, decompose at high temperatures to form a carbon skeleton, and play an important role in the fire resistance of fire retardant coatings. Flame retardant systems, also known as flame retardants, are the main components with the largest usage in fire retardant coatings and can play a flame retardant role. Flame retardants generally include intumescent flame retardants, inorganic flame retardants, silicone flame retardants and nanoparticle flame retardants. Intumescent flame retardants are the core components of intumescent fire retardant coatings that can play a flame retardant and fireproof role. According to the reaction mechanism, they can be divided into chemical reaction type and physical expansion type. The chemical reaction type mainly refers to the most widely used PCN system (i.e., ammonium polyphosphate-pentaerythritol-melamine system), in which ammonium polyphosphate is an acid source and catalyst. Its function is to promote the decomposition of the carbon former, so it is also called It is a dehydrating agent or carbonization accelerator. The catalyst decomposes into an acid with a dehydrating effect when heated. It catalyzes the dehydration of the carbonizing agent containing hydroxyl groups in the coating layer to form carbon, forming a three-dimensional carbonized layer that is non-flammable or low-flammable. It also decomposes to produce flame-retardant gases, such as ammonia, water vapor, carbon dioxide, etc., which dilute the concentration of oxygen in the carbonized layer, thereby preventing the combustion of the carbonized layer and enhancing the carbonization effect. Pentaerythritol is a carbon source, that is, a carbonizing agent, which is the basis of the intumescent flame retardant system. Without a carbonizing agent, the fire-retardant coating cannot form a carbonized layer. At high temperature, the carbon source is dehydrated under the action of the acid source, thereby forming a dense carbonized layer that covers the steel. The surface of the steel is protected by its own non-combustibility and heat insulation properties; melamine is the gas source, also known as the foaming agent, which is an indispensable part of the expansion flame retardant system. It can decompose at high temperature to produce non-flammable and non-toxic gases such as ammonia, water vapor, and carbon dioxide, which dilute the oxygen concentration and inhibit the combustion process, which is conducive to the expansion of the coating layer into a honeycomb-shaped carbonized layer; the decomposition temperature of the foaming agent, catalyst, and carbonizing agent must match, and the decomposition temperatures of the three must be coordinated to achieve the best effect, so that the fire retardant coating expands into a sponge-like or foam-like heat-insulating carbon layer. If the foaming agent has a higher decomposition temperature than other components, the coating will be oxidized and the carbonization temperature will be too high. If the temperature is low, the foaming agent will decompose and produce gas before the carbonizing agent is carbonized, which is not conducive to the foaming and expansion of the coating and cannot achieve the original effect. If the foaming agent has a higher decomposition temperature than other components, it will decompose and produce gas after the carbonization layer is formed, which is easy to cause damage to the carbonization layer and cannot play a heat insulation role. The PCN system has been the main system of fire retardant coatings in recent decades because the decomposition temperature of the foaming agent, catalyst and carbonizing agent is well matched. This system also needs to add titanium dioxide (titanium dioxide). At high temperatures, ammonium polyphosphate and titanium dioxide generate high-temperature resistant titanium pyrophosphate, which is organically and inorganically composited with the carbon layer to enhance the fire resistance of the foaming layer. The physical expansion type mainly refers to substances that can expand themselves when heated, mostly expandable graphite, and is used in conjunction with the PCN system.The dosage of the intumescent flame retardant system is large, generally accounting for 60-70% of the total mass of the coating, and the cost accounts for a large proportion. Therefore, in addition to ensuring that the intumescent flame retardant system has excellent fire retardant properties, it is also necessary to select an intumescent system with as little dosage and low cost as possible.

[0004] The main problems of the existing traditional PCN system are:

[0005] (1) Construction performance issues: Since the degree of polymerization of ammonium polyphosphate is unstable in the coating system, it will affect the consistency of the product and thus the construction performance of the product. Generally, 5 to 7 coats are required for a 2 mm thick coating, which results in high construction costs and high project costs.

[0006] (2) Water resistance of coating: Once the coating is soaked in water, its foaming performance will be greatly affected and its fire resistance will be greatly reduced;

[0007] (3) Environmental performance issues: Pentaerythritol, melamine, etc. will produce a large amount of toxic gases after burning, which have a pungent smell. In case of fire, the amount of toxic substances discharged is large;

[0008] (4) Cost issue: The material cost of the currently qualified product is over RMB 20 / kg, and the market price is around RMB 50 / kg. The high material cost and engineering cost are very high, which is difficult to accept for ordinary steel structure projects.

[0009] (5) Raw material source problem: Traditional system materials either use raw materials such as pentaerythritol and melamine, which are affected by international petrochemical prices, or use a large amount of ammonium polyphosphate, which consumes precious phosphorus resources and causes waste to the future agricultural fertilizer industry. Titanium dioxide is expensive and consumes too many resources. The overall resource consumption and cost are high. The source of raw materials is not wide and is highly restricted. Summary of the invention

[0010] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating. The present invention adopts raw materials such as starch, urea gypsum, formaldehyde-free urea-formaldehyde resin, vermiculite ore powder, graphite ore powder, etc. to provide a new carbon-nitrogen-sulfur-silicon steel structure fire retardant coating with less toxic gas emission during combustion, good construction performance, good fireproof performance, standardized raw material source, and low cost.

[0011] The present invention is to provide a method for preparing a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating, which is characterized by comprising the following steps:

[0012] a. Preparation of urea gypsum slurry:

[0013] (a) Ingredients: Take raw materials water, urea and gypsum according to the mass ratio of water: urea: gypsum = 30-80: 80: 56-88 and set aside;

[0014] The urea is CO(NH2)2, and its production and supply enterprises include Lutianhua Co., Ltd. and Sichuan Meifeng Chemical Co., Ltd.; the gypsum is CaSO4·2H2O, and its production and supply enterprises include Henan Yongtai Gypsum Co., Ltd. and Tai'an Qisheng Decoration Materials Co., Ltd.;

[0015] If the gypsum raw material is impure (i.e. not completely CaSO4.2H2O), the amount of urea and gypsum raw materials required is converted according to the content of CaSO4.2H2O in the gypsum raw material; the amount of gypsum raw material is increased by 1%-20% according to the dosage ratio of the chemical reaction formula; the calculation of the ratio of urea to gypsum raw materials, for example, the content of CaSO4.2H2O in the gypsum raw material is W CaSO4·2H2O , if the amount of gypsum exceeds N, then:

[0016]

[0017] In formula 5: m 石膏 is the amount of gypsum raw material, m 尿素 is the amount of urea, m CaSO4·2H2O is the dosage of CaSO4·2H2O, m CO(NH2)2 is the amount of urea, w CaSO4·2H2O is the weight percentage of CaSO4·2H2O in the gypsum raw material, N is the excess weight percentage of the gypsum raw material, M CO(NH2)2 is the molar mass of urea (60), M CaSO4·2H2O is the molar mass of CaSO4·2H2O (172).

[0018] (b) ball milling: take grinding balls with a ball-to-material weight ratio of 2-5 times, put them into a ball mill, then put water, urea and gypsum into the ball mill, and ball mill for 10-40 minutes at room temperature to obtain the urea-gypsum reaction material;

[0019] The chemical reaction equation of urea and gypsum is as follows:

[0020] 4CO(NH2) 2(s) +CaSO4·2H2O (s) =CaSO4·4CO(NH2) 2(s) +2H2O (Formula 6)

[0021] (c) adding the stabilizer to the urea-gypsum slurry at a mass ratio of urea-gypsum reaction material to stabilizer = 1000:2-20, stirring until the stabilizer is dissolved (completely), to obtain a (stable and non-stratified) urea-gypsum slurry;

[0022] b. Preparation of (formaldehyde-free) urea-formaldehyde resin:

[0023] (a) preparing a hydroxyethyl cellulose aqueous solution: taking hydroxyethyl cellulose and water in a mass ratio of hydroxyethyl cellulose to water = 1:50, adding the hydroxyethyl cellulose to the water (slowly) while stirring, and stirring until the hydroxyethyl cellulose is dissolved (completely), thereby obtaining a hydroxyethyl cellulose aqueous solution;

[0024] (b) Ingredients: Take raw material water, urea, formaldehyde, hydroxyethyl cellulose aqueous solution, hydrogen peroxide and defoamer according to the mass ratio of water: urea: formaldehyde: hydroxyethyl cellulose aqueous solution: hydrogen peroxide: defoamer = 25-45: 15-35: 20-40: 6-20: 0.1-0.5: 0.1-0.4, and take hydrochloric acid and sodium hydroxide aqueous solution for standby use;

[0025] The formaldehyde product production and provision enterprises include Chongqing Huihan Chemical Co., Ltd. and Nanjing Chemical Reagent Co., Ltd., which are industrial grade; the hydrochloric acid product production and provision enterprises include Jiangmen Guangyue Electrochemical Co., Ltd. and Guizhou Qingshang Chemical Co., Ltd., which can be industrial grade, and the hydrochloric acid can be a 37% by weight concentration of hydrogen chloride aqueous solution; the hydrogen peroxide product production and provision enterprises include Shenzhen Linsener Hydrogen Peroxide Co., Ltd. and Guangxi Jingu Hydrogen Peroxide Co., Ltd., which can be industrial grade, and the hydrogen peroxide is a 30% by weight concentration of hydrogen peroxide aqueous solution; the defoaming agent product production and provision enterprises and models include CS-300L Jiangsu Sixin Technology and THIX-278 Yantai Hengxin Chemical;

[0026] (c) Polymerization reaction: add urea to water, stir and heat until the urea is (completely) dissolved; then add formaldehyde, adjust the solution pH to 2-5 with hydrochloric acid, react for 15-60 minutes under (high-speed) stirring until white latex appears and the solution temperature reaches 70°C, continue (high-speed) stirring for 5-15 minutes, then add sodium hydroxide aqueous solution to adjust the solution pH to 8-10; then add defoaming agent to disperse evenly, (slowly) add hydrogen peroxide, and let it slowly decompose and oxidize the remaining formaldehyde until the bubbles basically disappear, so as to remove the remaining formaldehyde; then add hydroxyethyl cellulose aqueous solution, stir evenly, and stop stirring to obtain (formaldehyde-free) urea-formaldehyde resin;

[0027] c. Preparation of aluminum silicate refractory powder:

[0028] Take raw materials such as basalt aluminum silicate glass powder, aluminum silicate glass powder for construction or aluminum silicate basalt mineral powder, grind them to above 200 meshes to obtain aluminum silicate refractory powder;

[0029] d. Preparation of carbon, nitrogen, sulfur and silicon environmentally friendly intumescent fire retardant coating for steel structures:

[0030] (a) Ingredients: Take the raw materials according to the mass ratio of urea gypsum slurry: urea-formaldehyde resin: water: dispersant: defoamer: film-forming aid: preservative: starch: vermiculite powder: graphite: aluminum silicate refractory powder: acrylic emulsion: thickener = 3-8: 6-15: 20-40: 0.3-1: 0.1-0.3: 0.5-1: 0.1-0.2: 2-8: 8-20: 2-10: 10-20: 8-30: 0.1-0.5 and set aside;

[0031] (b) Mixing: under stirring, water, dispersant, defoamer, film-forming aid, preservative, urea gypsum slurry, urea-formaldehyde resin high-speed dispersing kettle are sequentially added and stirred evenly, starch, vermiculite powder, graphite, aluminum silicate refractory powder are then added in sequence under (high-speed) stirring until they are evenly dispersed, the stirring speed is lowered, acrylic emulsion is added and stirred and dispersed evenly, and then a thickener is added and stirred and dispersed evenly, and the consistency is adjusted to a suitable consistency to obtain a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating.

[0032] In the content of the present invention: the stabilizer described in step a (c) is hydroxyethyl cellulose or hydroxypropyl cellulose ether; the production and providing enterprises and models (or brands) of the hydroxyethyl cellulose products include QP100MH Dow Chemical, HS100000YP2 Klein Chemical, and the production and providing enterprises and models of hydroxypropyl cellulose ether products include 043400 Alfa Aesar (China) Chemical Co., Ltd., H0386 TCI (Shanghai) Chemical Industry Development Co., Ltd.;

[0033] In the present invention, step a(c) may further include step (d), namely, drying and grinding the obtained (stable and non-stratified) urea-gypsum slurry to obtain urea-gypsum powder.

[0034] In the present invention, the dispersant product in step d(a) is produced by a company and provided by a model (or brand) AA 4040 BASF, LP-91 Sichuan Hammite New Materials Technology Co., Ltd.; defoamer products are produced by CS-300L Jiangsu Sixin Technology, THIX-278 Yantai Hengxin Chemical; film-forming additives are produced by RTC-12 Runtai New Materials Co., Ltd., OT1200 Eastman China; preservatives are produced by B20 Guangzhou Jiankai Biotechnology Co., Ltd., ZB101 Zhongbei Fine Chemical; starch products are produced by HM-M200 Guangdong Huimei Starch Technology Co., Ltd., Foshan Huawu Huafeng Starch Co., Ltd.; vermiculite powder products are produced by Lingshou County Huashuo Mineral Products Processing Plant (40-60 mesh), Tuoxin Minerals (40-60 mesh): graphite products are produced by Qingdao Laixi Colloidal Graphite (expandable graphite) , Qingdao Risheng Graphite Co., Ltd. (expandable graphite); among the aluminum silicate refractory powders, the production and provision enterprises of basalt aluminum silicate glass powder include Lingshou County Junkai New Materials Co., Ltd. and Shijiazhuang Zhengyu New Materials Technology Co., Ltd., the production and provision enterprises of aluminum silicate glass powder for construction include Shanghai Renqian Chemical Technology Co., Ltd. and Foshan Youhe Chemical Technology Co., Ltd., the production and provision enterprises of aluminum silicate basalt mineral powder include Jiangsu Xuankun Basalt Fiber Technology Co., Ltd. and Shijiazhuang Jiuyue Mineral Products Co., Ltd., all of which are above 200 mesh; the production and provision enterprises and models of acrylic emulsion products include ZF-3718 Taixing Zhongfang Xingtai New Materials Co., Ltd. and SWW131 Anhui Sanwang Chemical Co., Ltd.; the production and provision enterprises and models of thickener products include TT-935 Qingdao Enze Chemical Co., Ltd. and ATW-2000 Qingzhou Beite Chemical Group Co., Ltd.

[0035] In the context of the present invention: the sodium hydroxide aqueous solution in step b(b) is preferably a sodium hydroxide aqueous solution having a weight percentage concentration of 20%.

[0036] The sodium hydroxide product is produced and provided by Zhejiang Donghui Chemical Co., Ltd., Zhongtai Chemical, etc., and can be industrial grade.

[0037] Compared with the prior art, the present invention has the following characteristics and beneficial effects:

[0038] (1) According to the present invention, the fireproof mechanism of urea gypsum is as follows: urea gypsum is a compound obtained by replacing the crystal water in gypsum with four molecules of urea (Formula 1). Differential thermal analysis shows that when urea gypsum is heated, a decomposition reaction shown in Formula 2 occurs at a temperature of 190 to 250°C, and a decomposition reaction shown in Formula 3 occurs at a temperature of 330 to 450°C, generating non-combustible gases such as carbon dioxide, ammonia, nitrogen, and water vapor, which can prevent air from entering, effectively dilute the oxygen in the air, inhibit combustion, and are particularly beneficial to the oxygen-deficient carbonization of the coating. At the same time, the carbon layer expands during the release of the gas generated by the decomposition, and finally the expanded carbon layer mixes with the residual calcium sulfate decomposed from the urea gypsum to form a new type of carbon-sulfur foaming layer;

[0039] CaSO4·2H2O+4CO(NH2)2=CaSO4·4CO(NH2)2+2H2O (Formula 1)

[0040] 3CaSO4·4CO(NH2)2=3CaSO4+2C3H6N6+6CO2+12NH3 (Formula 2)

[0041] 2C3H6N6+9O2=6CO2+6N2+6H2O (Formula 3)

[0042] (Formaldehyde-free) Urea-formaldehyde resin is an environmentally friendly resin that eliminates free formaldehyde. Its fireproof mechanism is as follows: Urea-formaldehyde resin is a product obtained by polymerization reaction of urea and formaldehyde under the action of a catalyst (alkaline or acidic catalyst) (such as Formula 4). Differential thermal analysis shows that when the temperature is in the stage of 65.0-260.0°C, the weight loss rate of urea-formaldehyde resin is 24.9%, which is the drying weight loss. Surface moisture and inherent moisture are released in this stage; the weight loss rate is the highest at 260.0-700.0°C, with a weight loss rate of 51.3%. Urea-formaldehyde resin undergoes thermal decomposition, that is, the molecular chain breaks to produce carbon dioxide, ammonia, nitrogen, water vapor and other non-combustible gases to provide a gas source, which can prevent air from entering, effectively dilute the oxygen in the air, inhibit combustion, and facilitate the oxygen-deficient carbonization of the incompletely burned molecular chains of urea-formaldehyde resin to form a dense carbon layer to provide a carbon source. The carbon layer expands during the release of the decomposition gas, so urea-formaldehyde resin can serve as a carbon source and gas source in the PCN expansion system;

[0043] nH2N-CO-NH2+nHCHO→H-[NH-CO-NH-CH2]-OH+(n-1)H2O (Formula 4)

[0044] Starch is a renewable material and a carbon source. Under combustion conditions, since the flame-retardant gas isolates the oxygen in the air, the starch will be affected by high temperature, dehydrated and carbonized to become a carbon source.

[0045] Aluminum silicate refractory powder (silicate composite glass powder) is a high-temperature binder. Its fireproof mechanism is as follows: it will partially melt under high temperature in the fire, adhere to the foaming material, increase the mechanical properties of the foaming layer, stabilize the foaming layer, and form a dense glass body on the surface of the foaming layer to prevent the flame from entering the foaming layer, thus playing a role in fireproofing;

[0046] Vermiculite (raw ore) powder and graphite (raw ore powder) are both physical expansion materials. They will physically expand and foam when exposed to fire. Under the action of the carbon layer and silicate composite glass binder, a stable foaming layer is formed. They have excellent high temperature resistance and play a main role in fire resistance.

[0047] (2) The carbon, nitrogen, sulfur, and silicon in the present invention are as follows: carbon refers to the carbon source component in starch and urea-formaldehyde resin, which plays the role of generating a carbon layer, which is the same as the effect of pentaerythritol in the traditional PCN system. Graphite ore powder is a carbonaceous material and also contains carbon; nitrogen refers to the nitrogen component in urea gypsum and urea-formaldehyde resin, which decomposes at high temperature to produce nitrogen, ammonia, etc. to isolate the air and foam, which is the same as the effect of melamine in the traditional PCN system; sulfur refers to the sulfate in urea gypsum, which forms a composite foaming layer with the carbon layer at high temperature to increase the fireproof ability; silicon refers to aluminum silicate glass, which plays a high-temperature bonding role, which is similar to the effect of titanium pyrophosphate in the traditional PCN system. Vermiculite ore powder is also a silicate mineral and also contains silicon. A new steel structure fire retardant coating system is obtained by compounding. The system of the present invention does not use traditional PCN system materials at all, and has significant effects on reducing project costs, improving construction performance and coating water and fire resistance;

[0048] (3) The present invention has the following technical features and advantages:

[0049] (3-1) Construction performance

[0050] Traditional system: Since the degree of polymerization of ammonium polyphosphate is unstable in the coating system, it will affect the consistency of the product and thus the construction performance of the product. Generally, after 2 mm of construction, 5 to 7 coats are required, and the construction cost is very high, resulting in high project cost;

[0051] The system of the present invention: Due to the leveling and anti-shrinkage effects of urea gypsum and the like, the thickness of the product of the present invention can reach 1.5 mm in one-time construction, and generally only two times are needed to achieve the required thickness without sagging, which greatly saves construction labor costs and reduces project costs;

[0052] (3-2) Water resistance

[0053] Traditional system: Once the applied coating is soaked in water, the foaming performance will be greatly affected and the fireproof performance will be greatly reduced;

[0054] The system of the present invention: the foaming performance is not affected by immersion and rain;

[0055] (3-3) Environmental performance

[0056] Traditional system: Pentaerythritol, melamine, etc. will produce a large amount of toxic gas after burning, which has a pungent smell and emits a large amount of toxic substances in case of fire;

[0057] The system of the present invention uses starch, urea, aluminum silicate fiber and minerals, graphite, gypsum and other synthetic processed materials, which emit less toxic gas and less harmful substances when burned;

[0058] (3-4) Cost advantage

[0059] Traditional system: The material cost of regular qualified products is more than 20 yuan / kg, and the market price is about 50 yuan / kg. The material cost is high and the project cost is very high, which makes it difficult for ordinary steel structure projects to be accepted by the market;

[0060] The system of the present invention: the material cost is only 3-5 yuan / kg, which is much lower than the traditional system, and has strong market competitiveness and broad market prospects;

[0061] (3-5) Advantages of raw material sources

[0062] Traditional system materials either use raw materials such as pentaerythritol and melamine, which are affected by international petrochemical prices, or use a large amount of ammonium polyphosphate, which consumes precious phosphorus resources and causes waste to the future agricultural fertilizer industry. Titanium dioxide is expensive and consumes too many resources. The overall resource consumption and cost are high, and the source of raw materials is not extensive, which is highly restricted.

[0063] The system of the present invention uses starch, urea, aluminum silicate fiber and minerals, graphite, gypsum and other synthetically processed materials. Starch is a renewable material with low cost. Urea comes from coal chemical industry and natural gas chemical industry. Domestic raw materials are abundant, the supply is large, and the price is low. Aluminum silicate fiber and minerals, graphite, gypsum and other inorganic mineral materials have abundant domestic production, convenient prices, can be stably obtained, and are not affected by international raw material fluctuations. They have important application prospects.

[0064] (4) The present invention is completely different from traditional PCN system materials. It has abundant raw materials, low prices, and simple preparation processes. It can significantly reduce project costs, significantly improve construction performance, coating water resistance and fire resistance, and improve environmental protection performance. It has good application prospects and strong practicality. DETAILED DESCRIPTION

[0065] The following embodiments are intended to further illustrate the present invention, but should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by technicians in this field based on the above-mentioned contents of the present invention still fall within the scope of protection of the present invention.

[0066] Embodiment 1:

[0067] A method for preparing a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating comprises the following steps:

[0068] a. Preparation of urea gypsum slurry:

[0069] (a) Ingredients: Take raw materials water, urea and gypsum in a mass ratio of water: urea: gypsum = 50:80:57 and set aside;

[0070] In this embodiment, urea is CO(NH2)2, and gypsum is CaSO4.2H2O;

[0071] (b) Ball milling: Grinding balls are taken at a ball-to-material weight ratio of 3 times, and are put into a ball mill. Water, urea, and gypsum are then put into the ball mill. The ball milling reaction is carried out at room temperature for 20 minutes to obtain the urea-gypsum reaction material;

[0072] (c) adding a stabilizer (hydroxyethyl cellulose) to the urea-gypsum slurry at a mass ratio of urea-gypsum reaction material to stabilizer = 1000:4, and stirring until the stabilizer is completely dissolved to obtain a stable urea-gypsum slurry without stratification;

[0073] b. Preparation of formaldehyde-free urea-formaldehyde resin:

[0074] (a) preparing a hydroxyethyl cellulose aqueous solution: taking hydroxyethyl cellulose and water in a mass ratio of hydroxyethyl cellulose to water = 1:50, slowly adding the hydroxyethyl cellulose into the water while stirring, and stirring until the hydroxyethyl cellulose is completely dissolved, thereby obtaining a hydroxyethyl cellulose aqueous solution;

[0075] (b) Ingredients: Take raw material water, urea, formaldehyde, hydroxyethyl cellulose aqueous solution, hydrogen peroxide and defoamer in a mass ratio of water: urea: formaldehyde: hydroxyethyl cellulose aqueous solution: hydrogen peroxide: defoamer = 42.5:28:22:6:0.1:0.4, and take hydrochloric acid and sodium hydroxide aqueous solution for later use;

[0076] (c) Polymerization reaction: urea is added to water, stirred and heated until the urea is completely dissolved; then formaldehyde is added, and the solution pH is adjusted to 2 with hydrochloric acid, and the reaction is carried out for 35 minutes under high-speed stirring. When white latex appears, the solution temperature is controlled at 70°C, and high-speed stirring is continued for 10 minutes, and then sodium hydroxide aqueous solution is added to adjust the solution pH to 8; then a defoaming agent is added to disperse evenly, and hydrogen peroxide is slowly added to allow it to slowly decompose and oxidize the remaining formaldehyde until the bubbles basically disappear, so as to remove the remaining formaldehyde; then a hydroxyethyl cellulose aqueous solution is added, stirred evenly, and stirring is stopped to obtain a formaldehyde-free urea-formaldehyde resin;

[0077] c. Preparation of aluminum silicate refractory powder:

[0078] Take raw materials such as basalt aluminum silicate glass powder, aluminum silicate glass powder for construction or aluminum silicate basalt mineral powder, grind them to above 200 meshes to obtain aluminum silicate refractory powder;

[0079] d. Preparation of carbon, nitrogen, sulfur and silicon environmentally friendly intumescent fire retardant coating for steel structures:

[0080] (a) Ingredients: Take the raw materials according to the mass ratio of urea gypsum slurry: urea-formaldehyde resin: water: dispersant: defoamer: film-forming aid: preservative: starch: vermiculite powder: graphite: aluminum silicate refractory powder (aluminum silicate basalt ore powder, 200 mesh): acrylic emulsion: thickener = 8:8:34:0.5:0.1:0.8:0.1:8:12:4:14:10:0.5 and set aside;

[0081] (b) Mixing: Add water, dispersant, defoamer, film-forming aid, preservative, urea gypsum slurry and urea-formaldehyde resin to a high-speed dispersing kettle in sequence under stirring and stir evenly. Then add starch, vermiculite powder, graphite and aluminum silicate refractory powder (i.e. aluminum silicate basalt ore powder, 200 mesh) in sequence under high-speed stirring until dispersed evenly. Lower the stirring speed, add acrylic emulsion and stir to disperse evenly. Then add thickener and stir to disperse evenly. Adjust to a suitable consistency to obtain a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating.

[0082] Embodiment 2~4:

[0083] A method for preparing a carbon, nitrogen, sulfur and silicon environmentally friendly steel structure intumescent fire retardant coating, the method steps are the same as those in Example 1, mainly changing the gypsum raw material in the preparation method of urea gypsum, and the other parts are the same and omitted, and the relevant parameters are shown in the following table:

[0084]

[0085] Embodiment 5~9:

[0086] A method for preparing a carbon, nitrogen, sulfur and silicon environmentally friendly steel structure intumescent fire retardant coating, the method steps are the same as those in Example 1, mainly changing the amount of urea gypsum added according to the chemical reaction dosage ratio due to the impurity of the gypsum raw material (i.e., not completely CaSO4.2H2O) in the preparation method of urea gypsum, and the other parts are the same and omitted. The relevant parameters are shown in the following table:

[0087]

[0088] Embodiments 10 to 12:

[0089] A method for preparing a carbon, nitrogen, sulfur and silicon environmentally friendly steel structure intumescent fire retardant coating, the method steps are the same as those in Example 1, mainly changing the ball-to-material weight ratio prepared by ball milling in the preparation method of urea gypsum, and the other parts are the same and omitted, and the relevant parameters are shown in the following table:

[0090]

[0091] Embodiments 13 to 17:

[0092] A method for preparing a carbon, nitrogen, sulfur and silicon environmentally friendly steel structure intumescent fire retardant coating, the method steps are the same as those in Example 1, mainly changing the ball milling reaction time of the ball milling preparation in the preparation method of urea gypsum, and the other parameters are the same and omitted. The relevant parameters are shown in the following table:

[0093]

[0094] Embodiment 18:

[0095] A method for preparing a carbon-nitrogen-sulfur-silicon environmentally friendly intumescent fire retardant coating for steel structures. The method steps are the same as those in Example 1, mainly except that the stabilizer in the preparation method of urea gypsum is changed to hydroxypropyl cellulose ether, and the rest are the same and omitted.

[0096] Embodiments 19 to 28:

[0097] A method for preparing a carbon, nitrogen, sulfur and silicon environmentally friendly steel structure intumescent fire retardant coating, the method steps are the same as those in Example 1, mainly changing the ratio of urea gypsum to stabilizer in the preparation method of urea gypsum, and the rest are the same and omitted. The relevant parameters are shown in the following table:

[0098]

[0099] Embodiments 29 to 34:

[0100] A method for preparing a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating, the method steps are the same as in Example 1, mainly changing the mass percentage of formaldehyde, hydrogen peroxide, and defoamer in the preparation of (formaldehyde-free) urea-formaldehyde resin. When the added formaldehyde content increases, the amount of residual formaldehyde will also increase, and the amount of hydrogen peroxide needs to be increased to eliminate the residual formaldehyde. At the same time, when the amount of hydrogen peroxide increases, the amount of bubbles generated will increase, and the amount of defoamer needs to be increased to eliminate the bubbles. The proportion change part is made up by water to 100%, and the others are the same and omitted. The relevant parameters are shown in the following table:

[0101]

[0102] Embodiments 35-40:

[0103] A method for preparing a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating, the method steps are the same as those in Example 1, mainly changing the mass percentage of hydrochloric acid, the polymerization reaction stirring time, and the mass percentage of 20% sodium hydroxide aqueous solution in the preparation of formaldehyde-free urea-formaldehyde resin. When the amount of hydrochloric acid increases, the pH of the solution decreases, the reaction rate of urea and formaldehyde increases, the required polymerization reaction stirring time decreases relatively, and the amount of 20% sodium hydroxide aqueous solution required to be added increases. The proportion change part is made up by water to 100%, and the others are the same and omitted. The relevant parameters are shown in the following table:

[0104]

[0105] Embodiments 41 to 49:

[0106] A method for preparing a carbon, nitrogen, sulfur and silicon environmentally friendly steel structure intumescent fire retardant coating, the method steps are the same as in Example 1, mainly changing the mass percentage of urea in the preparation of formaldehyde-free urea-formaldehyde resin, when the urea content increases, the residual formaldehyde content in the solution will decrease with the increase of urea, the proportion of the changed part is made up by water to 100%, and the others are the same and omitted. The relevant parameters are shown in the following table:

[0107]

[0108] Embodiments 50 to 57:

[0109] A method for preparing a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating, the method steps are the same as Example 1, mainly changing the time of continued stirring after the white latex appears in the polymerization reaction in the preparation of formaldehyde-free urea-formaldehyde resin. The longer the reaction time, the higher the degree of polymerization of the urea-formaldehyde resin. When the degree of polymerization is too high, the urea-formaldehyde resin will be over-polymerized, and the material will generate solid matter as a whole. The motor cannot be driven, stirring cannot be performed, and subsequent feeding and discharging operations cannot be performed, resulting in production failures and even safety accidents. This situation should be avoided. Others are the same and omitted. The relevant parameters are shown in the following table:

[0110]

[0111] Embodiment 58~59:

[0112] A method for preparing a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating, the method steps are the same as in Example 1, mainly changing the raw material of aluminum silicate refractory powder, and the other parameters are the same and omitted. The relevant parameters are shown in the following table:

[0113]

[0114] Embodiments 60 to 66:

[0115] A method for preparing a carbon, nitrogen, sulfur and silicon environmentally friendly steel structure intumescent fire retardant coating, the method steps are the same as in Example 1, mainly changing the grinding process mesh number in the preparation method of aluminum silicate refractory powder, and the other parameters are the same and omitted. The relevant parameters are shown in the following table:

[0116]

[0117] Embodiments 67 to 91:

[0118] A method for preparing a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating, the method steps are the same as in Example 1, mainly changing the mass percentage of the dispersant, defoamer, film-forming aid, preservative, and thickener in the preparation method of the carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating, the changed proportion is made up by water to 100%, and the others are the same and omitted. The relevant parameters are shown in the following table:

[0119]

[0120] After testing, the performance parameters of the above embodiments 67 to 76 are shown in the following table:

[0121]

[0122] Embodiment 92:

[0123] A method for preparing a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating, the method steps are the same as those in Example 1, mainly changing the urea gypsum in the method for preparing the carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating to a powder, the main difference between the urea gypsum slurry and the powder is the different water content, the weight ratio of water in the urea gypsum slurry: urea: gypsum = 50:80:75, the water comes from water and gypsum, the chemical formula of gypsum is CaSO4·2H2O, the relative molecular mass is 172, of which the relative molecular mass of 2 H2O is 36, so the relative molecular mass of water in gypsum accounts for 10% of the stone The relative molecular mass of the paste is 36 / 172*100%=20.93%, the total mass of water in the urea gypsum slurry is 50+20.93%*75=65.70, accounting for 65.70 / (50+80+75)*100%=32% of the total mass ratio of the urea gypsum slurry. Since the mass percentage of urea gypsum slurry added in Example 1 is 8, the mass percentage of water is 34, the mass percentage of urea gypsum powder to be added is 8*(1-0.32)=5.44, the percentage of water added is 36.56, and the contents of other substances are the same as in Example 1. Others are the same and omitted.

[0124] Embodiments 93-100:

[0125] A method for preparing a carbon, nitrogen, sulfur, and silicon environmentally friendly steel structure intumescent fire retardant coating, the method steps are the same as those in Example 1, mainly changing the mass percentage of urea gypsum slurry in the method for preparing a carbon, nitrogen, sulfur, and silicon environmentally friendly steel structure intumescent fire retardant coating, and the other parameters are the same and omitted. The relevant parameters are shown in the following table:

[0126]

[0127]

[0128] Embodiments 101 to 110:

[0129] A method for preparing a carbon, nitrogen, sulfur and silicon environmentally friendly steel structure intumescent fire retardant coating, the method steps are the same as in Example 1, mainly changing the mass percentage of urea-formaldehyde resin in the preparation method of the carbon, nitrogen, sulfur and silicon environmentally friendly steel structure intumescent fire retardant coating, the changed part is filled with water to 100%, and the others are the same and omitted. The relevant parameters are shown in the following table:

[0130]

[0131] Embodiments 111 to 117:

[0132] A method for preparing a carbon, nitrogen, sulfur, and silicon environmentally friendly steel structure intumescent fire retardant coating, the method steps are the same as those in Example 1, mainly changing the mass percentage of starch in the method for preparing the carbon, nitrogen, sulfur, and silicon environmentally friendly steel structure intumescent fire retardant coating, the changed portion is filled with water to 100%, and the others are the same and omitted. The relevant parameters are shown in the following table:

[0133]

[0134] Embodiments 118 to 123:

[0135] A method for preparing a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating, the method steps are the same as in Example 1, mainly changing the mass percentage of aluminum silicate refractory powder in the method for preparing the carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating, the changed proportion is made up by water to 100%, and the others are the same and omitted. The relevant parameters are shown in the following table:

[0136]

[0137] Embodiments 124-130:

[0138] A method for preparing a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating, the method steps are the same as in Example 1, mainly changing the mass percentage of vermiculite ore powder (i.e., vermiculite powder) in the method for preparing a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating, the changed part is filled with water to 100%, and the others are the same and omitted. The relevant parameters are shown in the following table:

[0139]

[0140] Embodiments 131 to 137:

[0141] A method for preparing a carbon, nitrogen, sulfur, and silicon environmentally friendly steel structure intumescent fire retardant coating, the method steps are the same as those in Example 1, mainly changing the mass percentage of graphite in the method for preparing the carbon, nitrogen, sulfur, and silicon environmentally friendly steel structure intumescent fire retardant coating, the changed proportion is filled with water to 100%, and the others are the same and omitted. The relevant parameters are shown in the following table:

[0142]

[0143] After testing, the performance parameters of the above embodiments 131 to 135 are shown in the following table:

[0144]

[0145] Embodiments 138 to 144:

[0146] A method for preparing a carbon, nitrogen, sulfur, and silicon environmentally friendly steel structure intumescent fire retardant coating, the method steps are the same as those in Example 1, mainly changing the mass percentage of the emulsion in the method for preparing the carbon, nitrogen, sulfur, and silicon environmentally friendly steel structure intumescent fire retardant coating, the changed part is filled with water to 100%, and the others are the same and omitted. The relevant parameters are shown in the following table:

[0147]

[0148] Embodiment 145:

[0149] A method for preparing a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating comprises the following steps:

[0150] a. Preparation of urea gypsum slurry:

[0151] (a) Ingredients: Take raw materials water, urea and gypsum in a mass ratio of water: urea: gypsum = 30:80:56 and set aside;

[0152] (b) Ball milling: Grinding balls are taken at a ball-to-material weight ratio of 2 times, and are put into a ball mill. Water, urea, and gypsum are then put into the ball mill. The ball milling reaction is carried out at room temperature for 10 minutes to obtain the urea-gypsum reaction material;

[0153] (c) adding the stabilizer to the urea-gypsum slurry at a mass ratio of urea-gypsum reaction material to stabilizer = 1000:2, stirring until the stabilizer is dissolved (completely), and obtaining a stable urea-gypsum slurry without stratification;

[0154] b. Preparation of (formaldehyde-free) urea-formaldehyde resin:

[0155] (a) preparing a hydroxyethyl cellulose aqueous solution: taking hydroxyethyl cellulose and water in a mass ratio of hydroxyethyl cellulose to water = 1:50, adding the hydroxyethyl cellulose to the water (slowly) while stirring, and stirring until the hydroxyethyl cellulose is dissolved (completely), thereby obtaining a hydroxyethyl cellulose aqueous solution;

[0156] (b) Ingredients: Take raw material water, urea, formaldehyde, hydroxyethyl cellulose aqueous solution, hydrogen peroxide and defoamer in a mass ratio of water: urea: formaldehyde: hydroxyethyl cellulose aqueous solution: hydrogen peroxide: defoamer = 25:15:20:6:0.1:0.1, and take hydrochloric acid and sodium hydroxide aqueous solution for later use;

[0157] (c) Polymerization reaction: add urea to water, stir and heat until the urea is (completely) dissolved; then add formaldehyde, adjust the solution pH to 2 with hydrochloric acid, react for 15 minutes under (high-speed) stirring. When white latex appears, the solution temperature is controlled at 68°C, continue (high-speed) stirring for 5 minutes, and then add sodium hydroxide aqueous solution to adjust the solution pH to 8; then add defoaming agent to disperse evenly, (slowly) add hydrogen peroxide, and let it slowly decompose and oxidize the remaining formaldehyde until the bubbles basically disappear, so as to remove the remaining formaldehyde; then add hydroxyethyl cellulose aqueous solution, stir evenly, and stop stirring to obtain (formaldehyde-free) urea-formaldehyde resin;

[0158] c. Preparation of aluminum silicate refractory powder:

[0159] Take raw materials such as basalt aluminum silicate glass powder, aluminum silicate glass powder for construction or aluminum silicate basalt mineral powder, grind them to above 200 meshes to obtain aluminum silicate refractory powder;

[0160] d. Preparation of carbon, nitrogen, sulfur and silicon environmentally friendly intumescent fire retardant coating for steel structures:

[0161] (a) Ingredients: Take the raw materials according to the mass ratio of urea gypsum slurry: urea-formaldehyde resin: water: dispersant: defoamer: film-forming aid: preservative: starch: vermiculite powder: graphite: aluminum silicate refractory powder: acrylic emulsion: thickener = 3:6:20:0.3:0.1:0.5:0.1:2:8:2:10:8:0.1 and set aside;

[0162] (b) Mixing: Add water, dispersant, defoamer, film-forming aid, preservative, urea gypsum slurry and urea-formaldehyde resin to a mixer with an agitator in sequence while stirring, stir evenly, then add starch, vermiculite powder, graphite and aluminum silicate refractory powder in sequence while stirring (at high speed) until they are evenly dispersed, lower the stirring speed, add acrylic emulsion and stir to disperse evenly, then add thickener and stir to disperse evenly, adjust to a suitable consistency, and thus obtain a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating.

[0163] Embodiment 146:

[0164] A method for preparing a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating comprises the following steps:

[0165] a. Preparation of urea gypsum slurry:

[0166] (a) Ingredients: Take raw materials water, urea and gypsum in a mass ratio of water: urea: gypsum = 80:80:88 and set aside;

[0167] (b) Ball milling: Grinding balls are taken at a ball-to-material weight ratio of 5 times, and are put into a ball mill. Water, urea, and gypsum are then put into the ball mill. The ball milling reaction is carried out at room temperature for 40 minutes to obtain the urea-gypsum reaction material;

[0168] (c) adding the stabilizer to the urea-gypsum slurry at a mass ratio of urea-gypsum reaction material to stabilizer = 1000:20, stirring until the stabilizer is dissolved (completely), and obtaining a stable urea-gypsum slurry without stratification;

[0169] b. Preparation of (formaldehyde-free) urea-formaldehyde resin:

[0170] (a) preparing a hydroxyethyl cellulose aqueous solution: taking hydroxyethyl cellulose and water in a mass ratio of hydroxyethyl cellulose to water = 1:50, adding the hydroxyethyl cellulose to the water (slowly) while stirring, and stirring until the hydroxyethyl cellulose is dissolved (completely), thereby obtaining a hydroxyethyl cellulose aqueous solution;

[0171] (b) Ingredients: Take raw material water, urea, formaldehyde, hydroxyethyl cellulose aqueous solution, hydrogen peroxide and defoamer in a mass ratio of water: urea: formaldehyde: hydroxyethyl cellulose aqueous solution: hydrogen peroxide: defoamer = 45:35:40:20:0.5:0.4, and take hydrochloric acid and sodium hydroxide aqueous solution for later use;

[0172] (c) Polymerization reaction: add urea to water, stir and heat until the urea is (completely) dissolved; then add formaldehyde, adjust the solution pH to 5 with hydrochloric acid, react for 160 minutes under (high-speed) stirring until white latex appears, control the solution temperature at 72°C, continue (high-speed) stirring for 15 minutes, then add sodium hydroxide aqueous solution to adjust the solution pH to 10; then add defoaming agent to disperse evenly, (slowly) add hydrogen peroxide, and let it slowly decompose and oxidize the remaining formaldehyde until the bubbles basically disappear, so as to remove the remaining formaldehyde; then add hydroxyethyl cellulose aqueous solution, stir evenly, and stop stirring to obtain (formaldehyde-free) urea-formaldehyde resin;

[0173] c. Preparation of aluminum silicate refractory powder:

[0174] Take raw materials such as basalt aluminum silicate glass powder, aluminum silicate glass powder for construction or aluminum silicate basalt mineral powder, grind them to above 200 meshes to obtain aluminum silicate refractory powder;

[0175] d. Preparation of carbon, nitrogen, sulfur and silicon environmentally friendly intumescent fire retardant coating for steel structures:

[0176] (a) Ingredients: Take the raw materials according to the mass ratio of urea gypsum slurry: urea-formaldehyde resin: water: dispersant: defoamer: film-forming aid: preservative: starch: vermiculite powder: graphite: aluminum silicate refractory powder: acrylic emulsion: thickener = 8:15:40:1:0.3:1:2:8:20:10:20:30:0.5 and set aside;

[0177] (b) Mixing: Add water, dispersant, defoamer, film-forming aid, preservative, urea gypsum slurry and urea-formaldehyde resin to a mixer with an agitator in sequence while stirring, stir evenly, then add starch, vermiculite powder, graphite and aluminum silicate refractory powder in sequence while stirring (at high speed) until they are evenly dispersed, lower the stirring speed, add acrylic emulsion and stir to disperse evenly, then add thickener and stir to disperse evenly, adjust to a suitable consistency, and thus obtain a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating.

[0178] Embodiment 147:

[0179] A method for preparing a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating comprises the following steps:

[0180] a. Preparation of urea gypsum slurry:

[0181] (a) Ingredients: Take raw materials water, urea and gypsum in a mass ratio of water: urea: gypsum = 45:80:72 and set aside;

[0182] (b) Ball milling: Grinding balls are taken at a ball-to-material weight ratio of 3.5 times, and are put into a ball mill. Water, urea, and gypsum are then put into the ball mill. The ball milling reaction is carried out at room temperature for 25 minutes to obtain the urea-gypsum reaction material;

[0183] (c) adding the stabilizer to the urea-gypsum slurry at a mass ratio of urea-gypsum reaction material to stabilizer = 1000:11, stirring until the stabilizer is dissolved (completely), and obtaining a stable urea-gypsum slurry without stratification;

[0184] b. Preparation of (formaldehyde-free) urea-formaldehyde resin:

[0185] (a) preparing a hydroxyethyl cellulose aqueous solution: taking hydroxyethyl cellulose and water in a mass ratio of hydroxyethyl cellulose to water = 1:50, adding the hydroxyethyl cellulose to the water (slowly) while stirring, and stirring until the hydroxyethyl cellulose is dissolved (completely), thereby obtaining a hydroxyethyl cellulose aqueous solution;

[0186] (b) Ingredients: Take raw material water, urea, formaldehyde, hydroxyethyl cellulose aqueous solution, hydrogen peroxide and defoamer in a mass ratio of water: urea: formaldehyde: hydroxyethyl cellulose aqueous solution: hydrogen peroxide: defoamer = 35:25:30:13:0.3:0.25, and take hydrochloric acid and sodium hydroxide aqueous solution for later use;

[0187] (c) Polymerization reaction: add urea to water, stir and heat until the urea is (completely) dissolved; then add formaldehyde, adjust the solution pH to 4 with hydrochloric acid, react for 38 minutes under (high-speed) stirring until white latex appears, control the solution temperature at 70°C, continue (high-speed) stirring for 10 minutes, then add sodium hydroxide aqueous solution to adjust the solution pH to 9; then add defoaming agent to disperse evenly, (slowly) add hydrogen peroxide, and let it slowly decompose and oxidize the remaining formaldehyde until the bubbles basically disappear, so as to remove the remaining formaldehyde; then add hydroxyethyl cellulose aqueous solution, stir evenly, and stop stirring to obtain (formaldehyde-free) urea-formaldehyde resin;

[0188] c. Preparation of aluminum silicate refractory powder:

[0189] Take raw materials such as basalt aluminum silicate glass powder, aluminum silicate glass powder for construction or aluminum silicate basalt mineral powder, grind them to above 200 meshes to obtain aluminum silicate refractory powder;

[0190] d. Preparation of carbon, nitrogen, sulfur and silicon environmentally friendly intumescent fire retardant coating for steel structures:

[0191] (a) Ingredients: Take the raw materials according to the mass ratio of urea gypsum slurry: urea-formaldehyde resin: water: dispersant: defoamer: film-forming aid: preservative: starch: vermiculite powder: graphite: aluminum silicate refractory powder: acrylic emulsion: thickener = 5.5:10.2:30:0.6:0.2:0.8:0.15:5:14:6:15:19:0.3 and set aside;

[0192] (b) Mixing: Add water, dispersant, defoamer, film-forming aid, preservative, urea gypsum slurry and urea-formaldehyde resin to a mixer with an agitator in sequence while stirring, stir evenly, then add starch, vermiculite powder, graphite and aluminum silicate refractory powder in sequence while stirring (at high speed) until they are evenly dispersed, lower the stirring speed, add acrylic emulsion and stir to disperse evenly, then add thickener and stir to disperse evenly, adjust to a suitable consistency, and thus obtain a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating.

[0193] In the above embodiment:

[0194] The urea is CO(NH2)2, and the product production and supply enterprises include Lutianhua Co., Ltd. and Sichuan Meifeng Chemical Co., Ltd.; the gypsum is CaSO4·2H2O, and the gypsum raw material product production and supply enterprises include Henan Yongtai Gypsum Co., Ltd. and Tai'an Qisheng Decorative Materials Co., Ltd., and it can also be other commercially available products;

[0195] The formaldehyde product production and provision enterprises include Chongqing Huihan Chemical Co., Ltd. and Nanjing Chemical Reagent Co., Ltd., which are industrial grade; the hydrochloric acid product production and provision enterprises include Jiangmen Guangyue Electrochemical Co., Ltd. and Guizhou Qingshang Chemical Co., Ltd., which can be industrial grade, and the hydrochloric acid is a 37% by weight concentration of hydrogen chloride aqueous solution; the hydrogen peroxide product production and provision enterprises include Shenzhen Linsener Hydrogen Peroxide Co., Ltd. and Guangxi Jingu Hydrogen Peroxide Co., Ltd., which can be industrial grade, and the hydrogen peroxide is a 30% by weight concentration of hydrogen peroxide aqueous solution;

[0196] The defoamer product manufacturer and model is Jiangsu Sixin Technology CS-300L;

[0197] The manufacturer and model (or brand) of the hydroxyethyl cellulose product is Dow Chemical QP100MH, and the manufacturer and model of the hydroxypropyl cellulose ether product is TCI (Shanghai) Chemical Industry Development Co., Ltd. H0386;

[0198] The dispersant product production and providing enterprise and model is Sichuan Hammite New Material Technology Co., Ltd. LP-91;

[0199] The film-forming aid product manufacturer and model is RTC-12 Runtai New Materials Co., Ltd.;

[0200] The manufacturer and model of the preservative product is Guangzhou Jiankai Biotechnology Co., Ltd. B20;

[0201] The starch product manufacturer is Foshan Huawu Huafeng Starch Co., Ltd.

[0202] The vermiculite powder product production and specification is provided by Lingshou County Huashuo Mineral Products Processing Plant (40-60 mesh):

[0203] The graphite product manufacturer is Qingdao Laixi Colloidal Graphite (expandable graphite);

[0204] Among the aluminum silicate refractory powders, the manufacturer of basalt aluminum silicate glass powder products is Lingshou Junkai New Materials Co., Ltd., the manufacturer of aluminum silicate glass powder products for construction is Foshan Youhe Chemical Technology Co., Ltd., and the manufacturer of aluminum silicate basalt mineral powder products is Jiangsu Xuankun Basalt Fiber Technology Co., Ltd.;

[0205] The acrylic emulsion product is produced and provided by the enterprise and model number Taixing Zhongfang Xingtai New Materials Co., Ltd. ZF-3718;

[0206] The thickener product is produced by Qingdao Enze Chemical Co., Ltd. and its model is TT-935;

[0207] The sodium hydroxide aqueous solution is a sodium hydroxide aqueous solution with a weight percentage concentration of 20%. The sodium hydroxide product is produced and provided by Zhejiang Donghui Chemical Co., Ltd., Zhongtai Chemical, etc., and is industrial grade.

[0208] In the above embodiments: all the raw materials used are commercially available products.

[0209] In the above embodiments: the percentages used, unless otherwise specified, are all mass (weight) percentages or percentages known to those skilled in the art; the mass (weight) parts may be grams or kilograms.

[0210] In the above embodiments, the process parameters (temperature, time, concentration, etc.) in each step and the numerical values ​​of the amounts of each component are ranges, and any point can be applied.

[0211] The content of the present invention and the technical content not specifically described in the above embodiments are the same as the prior art.

[0212] The present invention is not limited to the above embodiments, and all of the contents of the present invention can be implemented and have the above good effects.

Claims

1. A method for preparing a carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating, characterized in that The following steps are involved: a. Preparation of urea gypsum slurry: (a) Ingredients: Take raw materials water, urea and gypsum according to the mass ratio of water: urea: gypsum = 30-80:80:56-88 and set aside; (b) Ball milling: Take grinding balls with a ball-to-material weight ratio of 2-5 times, put them into a ball mill, then put water, urea and gypsum into the ball mill, and ball mill for 10-40 minutes at room temperature to obtain the urea-gypsum reaction material; (c) adding the stabilizer to the urea-gypsum slurry in a mass ratio of urea-gypsum reaction material to stabilizer = 1000:2-20, stirring until the stabilizer is dissolved, to obtain urea-gypsum slurry; b. Preparation of urea-formaldehyde resin: (a) preparing a hydroxyethyl cellulose aqueous solution: taking hydroxyethyl cellulose and water in a mass ratio of hydroxyethyl cellulose to water = 1:50, adding the hydroxyethyl cellulose to the water under stirring, and stirring until the hydroxyethyl cellulose is dissolved, thereby obtaining a hydroxyethyl cellulose aqueous solution; (b) Ingredients: Take raw material water, urea, formaldehyde, hydroxyethyl cellulose aqueous solution, hydrogen peroxide and defoamer according to the mass ratio of water: urea: formaldehyde: hydroxyethyl cellulose aqueous solution: hydrogen peroxide: defoamer = 25-45: 15-35: 20-40: 6-20: 0.1-0.5: 0.1-0.4, and take hydrochloric acid and sodium hydroxide aqueous solution for use; (c) Polymerization reaction: add urea to water, stir and heat until the urea is dissolved; then add formaldehyde, adjust the solution pH to 2-5 with hydrochloric acid, react for 15-60 minutes under stirring, control the solution temperature at 68-72°C, continue stirring for 5-15 minutes, add sodium hydroxide aqueous solution to adjust the solution pH to 8-10; then add defoamer and disperse evenly, add hydrogen peroxide, then add hydroxyethyl cellulose aqueous solution, stir evenly, stop stirring, and urea-formaldehyde resin is obtained; c. Preparation of aluminum silicate refractory powder: Take raw material basalt aluminum silicate glass powder, building aluminum silicate glass powder or aluminum silicate basalt mineral powder, grind to above 200 mesh, and then prepare aluminum silicate refractory powder; d. Preparation of carbon, nitrogen, sulfur and silicon environmentally friendly intumescent fire retardant coating for steel structures: (a) Ingredients: Take the raw materials according to the mass ratio of urea gypsum slurry: urea-formaldehyde resin: water: dispersant: defoaming agent: film-forming aid: preservative: starch: vermiculite powder: graphite: aluminum silicate refractory powder: acrylic emulsion: thickener = 3-8: 6-15: 20-40: 0.3-1: 0.1-0.3: 0.5-1: 0.1-0.2: 2-8: 8-20: 2-10: 10-20: 8-30: 0.1-0.5 and set aside; (b) Mixing: Add water, dispersant, defoamer, film-forming aid, preservative, urea gypsum slurry and urea-formaldehyde resin to a high-speed dispersing kettle in sequence while stirring, stir evenly, then add starch, vermiculite powder, graphite and aluminum silicate refractory powder in sequence while stirring until dispersed evenly, lower the stirring speed, add acrylic emulsion and stir to disperse evenly, then add thickener and stir to disperse evenly, adjust to a suitable consistency, and thus obtain carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating.

2. The method for preparing the carbon, nitrogen, sulfur and silicon environmentally friendly steel structure intumescent fire retardant coating according to claim 1, characterized in that: The stabilizer in step a(c) is hydroxyethyl cellulose or hydroxypropyl cellulose ether.

3. The method for preparing the carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating according to claim 1, characterized in that: Step a(c) also includes step (d), namely, drying and grinding the obtained urea-gypsum slurry to obtain urea-gypsum powder.

4. The method for preparing the carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating according to claim 1, 2 or 3, characterized in that: The dispersant products produced and provided by the enterprises and models in step d (a) are Dispex® AA 4040 BASF of Germany and LP-91 Sichuan Hammite New Materials Technology Co., Ltd.; the defoamer products produced and provided by the enterprises and models are CS-300L Jiangsu Sixin Technology and THIX-278 Yantai Hengxin Chemical; the film-forming agent products produced and provided by the enterprises and models are RTC-12 Runtai New Materials Co., Ltd. and OT1200 Eastman China; the preservative products produced and provided by the enterprises and models are B20 Guangzhou Jiankai Biotechnology Co., Ltd. and ZB101 Zhongbei Fine Chemical; the acrylic emulsion products produced and provided by the enterprises and models are ZF-3718 Taixing Zhongfang Xingtai New Materials Co., Ltd. and SWW131 Anhui Sanwang Chemical Co., Ltd.; the thickener products produced and provided by the enterprises and models are TT-935 Qingdao Enze Chemical Co., Ltd. and ATW-2000 Qingzhou Beite Chemical Group Co., Ltd.

5. The method for preparing the carbon-nitrogen-sulfur-silicon environmentally friendly steel structure intumescent fire retardant coating according to claim 1, 2 or 3, characterized in that: The sodium hydroxide aqueous solution in step b (b) is a sodium hydroxide aqueous solution with a weight percentage concentration of 20%.

Images