Intumescent fire retardant coating based on sewage treatment solid waste and preparation method of intumescent fire retardant coating

Abstract

The invention discloses an intumescent fireproof coating based on sewage treatment solid waste and a preparation method thereof, and relates to the technical field of fireproof coatings, the intumescent fireproof coating comprises the following raw materials by weight: 3-15 parts of struvite, 30-50 parts of a film-forming emulsion, 7-15 parts of a pigment filler, 23-28 parts of an intumescent flame retardant, 7-8 parts of a plasticizer, 1-1.5 parts of an auxiliary agent, and 5-15 parts of water; according to the invention, high-value utilization of struvite is realized, and by adding struvite, the fireproof performance of the coating can be improved, the bonding strength of the coating can also be improved, and a crack-free coating is formed.

Description

Technical Field

[0001] The invention relates to the technical field of fire retardant coatings, and in particular to an intumescent fire retardant coating based on solid waste from sewage treatment and a preparation method thereof. Background Art

[0002] Steel structures are widely used in industry and construction due to their high strength and convenient construction. However, some steel structure materials currently used generally have the disadvantage of poor fire resistance. Especially when the temperature is higher than 538°C, the strength and hardness of the steel structure will be completely lost. Therefore, the heat resistance of steel structures also brings serious safety hazards to people's production and life. Coating the surface of the steel structure before use is a feasible and effective method.

[0003] In sewage treatment, struvite precipitation is an effective technology for nitrogen and phosphorus removal. It purifies sewage by adding magnesium ions to sewage containing phosphate and ammonia nitrogen to generate insoluble struvite precipitates. The struvite precipitation method has broad application prospects in sewage treatment due to its advantages of low cost, high yield and convenient operation.

[0004] Struvite is a solid waste from sewage treatment. It is usually recycled as a slow-release fertilizer, which can also prevent high cleaning costs due to its precipitation in sewage treatment pipes and pumps. However, the sales price of struvite as a fertilizer is low, and its value can be increased by using it as a phosphorus-based flame retardant. When heated, struvite releases a large amount of ammonia and water vapor, absorbs a large amount of heat and dilutes oxygen, thereby achieving the purpose of flame retardancy. At the same time, the phosphoric acid released at high temperature catalyzes the reaction with the organic matrix to produce a carbon layer to isolate the flame from spreading to the substrate, and generates magnesium orthophosphate and magnesium pyrophosphate to form a dense ceramic layer with good thermal insulation and protection. In addition, since struvite comes from sewage, its use in flame retardants can offset the demand for phosphorus mining. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide an intumescent fire-retardant coating based on sewage treatment solid waste and a preparation method thereof, which can not only realize the high-value utilization of struvite, but also improve the fire-retardant performance of the coating by adding struvite, and also improve the bonding strength of the coating to form a crack-free coating.

[0006] The technical problem to be solved by the present invention is achieved by adopting the following technical solutions:

[0007] The first object of the present invention is to provide an intumescent fire retardant coating based on solid waste from sewage treatment, comprising the following raw materials in parts by weight:

[0008]

[0009] The second object of the present invention is to provide a method for preparing an intumescent fire-retardant coating based on solid waste from sewage treatment, wherein struvite, film-forming emulsion, pigment filler, intumescent flame retardant, plasticizer, additive and water are uniformly mixed according to a proportion to obtain a fire-retardant coating.

[0010] The third object of the present invention is to provide the use of the intumescent fire retardant coating based on sewage treatment solid waste in steel structures.

[0011] The beneficial effects of the present invention are as follows: the present invention uses the solid waste struvite generated when ammonia nitrogen and phosphorus are recovered from sewage by the struvite precipitation method as a raw material to prepare an intumescent fire retardant coating, and applies the intumescent fire retardant coating to the coating protection of steel structures, which not only realizes the high-value utilization of the struvite, but also improves the fire retardant performance of the coating, significantly improves the bonding strength of the coating, forms a crack-free coating on the surface of the steel structure, and plays a good protective role on the steel structure. DETAILED DESCRIPTION

[0012] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with specific embodiments.

[0013] The present invention provides an intumescent fire retardant coating based on solid waste from sewage treatment, comprising the following raw materials in parts by weight:

[0014]

[0015] Furthermore, the struvite is solid waste generated when ammonia nitrogen and phosphorus are recovered from sewage using a struvite precipitation method.

[0016] Further, the film-forming emulsion includes but is not limited to one or more of Wacker EP-707K emulsion, Bardeful 6067 emulsion, Polycar BLJ-8439 emulsion, Celanese LDM2301 emulsion, and Clariant DM230 emulsion. When the film-forming emulsion adopts one emulsion, Bardeful 6067 emulsion is preferred. Compared with other emulsions, Bardeful 6067 emulsion has relatively better comprehensive performance. The film-forming emulsion can make the coating form a continuous film on the surface of the substrate to prevent the substrate from being physically or chemically affected.

[0017] Furthermore, the pigments and fillers include but are not limited to one or more of titanium dioxide, calcium carbonate, talcum powder and magnesium phosphate. The main functions of pigments and fillers include increasing the hiding power of the coating, improving the mechanical properties of the coating, and improving the leveling and construction performance of the coating.

[0018] Further, the intumescent flame retardant includes but is not limited to one or more of ammonium polyphosphate, melamine, melamine pyrophosphate, melamine phosphate, polyphosphate melamine, diammonium hydrogen phosphate, diammonium phosphate, and ammonium pyrophosphate. Wherein, the ammonium polyphosphate is type II ammonium polyphosphate, and the degree of polymerization n≥1000. The intumescent flame retardant forms a carbonate layer by foaming and expansion. This carbonate layer has high heat resistance and antioxidant properties, and can achieve the same flame retardant effect at a lower addition amount. In addition, a carbonaceous foam layer will be generated on the surface of the intumescent flame retardant when it burns, which has the effects of heat insulation, oxygen isolation, smoke suppression, and drip prevention. It has excellent flame retardant properties, and produces low smoke, low toxicity, and no corrosive gas.

[0019] Furthermore, the plasticizer is one of pentaerythritol ester, phthalate, dioctyl adipate, and tricresyl phosphate. The role of the plasticizer in the coating is to increase the flexibility of the coating and improve the mechanical properties of the coating.

[0020] Furthermore, the auxiliary agent includes but is not limited to one or more of a defoamer, a dispersant, a thickener, and an anti-flash rust agent. Among them, the defoamer includes but is not limited to one or more of polyether defoamers, silicone defoamers, mineral oil defoamers, amide defoamers, phosphate defoamers, fatty acids and fatty acid ester defoamers; the dispersant is a surfactant; the thickener includes but is not limited to one or more of hydroxyethyl cellulose, polyvinyl alcohol, polyethylene glycol, polyamide, and bentonite; the anti-flash rust agent includes but is not limited to one or more of ammonium carbonate, sodium benzoate, sodium nitrite, sodium silicate, sodium phosphate, and triethanolamine.

[0021] Furthermore, the water is deionized water. Since deionized water removes individual ions in water, it can reduce impurities in the coating, improve the stability of the coating, and avoid coating failure caused by water quality problems.

[0022] The present invention also provides a method for preparing an intumescent fire-retardant coating based on solid waste from sewage treatment, wherein struvite, film-forming emulsion, pigment filler, intumescent flame retardant, plasticizer, additive and water are uniformly mixed according to a proportion to obtain the fire-retardant coating.

[0023] The present invention provides the application of the intumescent fire retardant coating based on sewage treatment solid waste in steel structure. By coating the intumescent fire retardant coating of the present invention on the surface of the steel structure, the fire resistance of the steel structure can be effectively improved, thereby playing a good protective role for the steel structure.

[0024] The struvite used in the following examples and comparative examples is an amorphous powder of 1000-2000 mesh, which is obtained by drying and crushing the solid waste generated in the sewage ammonia nitrogen removal process of Bengbu Huaiyuan Muyuan Agriculture and Animal Husbandry Co., Ltd.; the ammonium polyphosphate is type II ammonium polyphosphate with a degree of polymerization n≥1000.

[0025] The performance test method of the fire retardant coating prepared in the following examples and comparative examples:

[0026] Drying time (surface drying) is tested according to the finger touch method specified in GB 1728-1979;

[0027] Initial drying crack resistance is tested according to 6.10 of GB 9979-2015;

[0028] The bonding strength is tested according to 6.4.4 of GB 14907-2018;

[0029] The fire resistance performance is in accordance with GB / T 9978.1-2008 building cellulose fire heating conditions, and the specimen coating thickness is 2.0mm.

[0030] Example 1

[0031] Table 1

[0032]

[0033]

[0034] The fire retardant coating was prepared according to the ratio in Table 1. The specific preparation steps are as follows:

[0035] (1) Grind the struvite and pigment filler with a ball mill and pass through a 600-mesh sieve to control the particle size within 25 μm.

[0036] (2) Deionized water, defoamer, dispersant and anti-flash rust agent are stirred at a speed of 1000 r / min for 5 minutes, and then an intumescent flame retardant, a plasticizer, and the struvite and pigments treated in step (1) are added, and stirred at a speed of 2000 r / min for 30 minutes. Then, a film-forming emulsion is added, and stirred at a speed of 500 r / min for 60 minutes. Finally, a thickener is added, and stirred at a speed of 500 r / min for 30 minutes to obtain a fire retardant coating.

[0037] Examples 2 to 4 and Comparative Examples 1 to 2

[0038] The method of Example 1 was followed, except that the amount of the raw materials was adjusted, and the unit is part by weight, as shown in Table 2. The fire retardant coatings prepared in Examples 2 to 4 and Comparative Examples 1 to 2 were tested for performance, and the results are shown in Table 2.

[0039] Table 2

[0040]

[0041]

[0042] As can be seen from Table 2, when no guano is used or the amount of guano stone is too little, the bonding strength of the coating is small and the fire resistance is poor; when the amount of guano stone is too much, the bonding strength of the coating is small, the fire resistance is poor, and the coating will crack after drying. Therefore, the amount of guano stone in the coating needs to be controlled within a certain range.

[0043] Embodiments 5 to 8

[0044] The method of Example 1 was followed, except that the type of film-forming emulsion was changed, as shown in Table 3. The fire retardant coatings prepared in Examples 5 to 8 were tested for performance, and the results are shown in Table 3.

[0045] Table 3

[0046]

[0047]

[0048] As can be seen from Table 3, Wacker EP-707K emulsion, Badrich 6067 emulsion, Polycar BLJ-8439 emulsion, Celanese LDM2301 emulsion and Clariant DM230 emulsion can all be used as film-forming emulsions for fire retardant coatings, but Badrich 6067 emulsion has the best performance.

[0049] Examples 9 to 11

[0050] The method of Example 1 was followed, except that the type of intumescent flame retardant was changed, as shown in Table 4. The fire retardant coatings prepared in Examples 9 to 11 were tested for performance, and the results are shown in Table 4.

[0051] Table 4

[0052]

[0053] As can be seen from Table 4, the intumescent flame retardants have good effects when used alone or in combination, but the best effect is achieved when the ratio of ammonium polyphosphate to melamine is 3:1.

[0054] In summary, the use of struvite to prepare fire-retardant coatings in the present invention can not only improve the fire resistance of the coating, but also improve the bonding strength and initial drying crack resistance of the coating, so that the prepared fire-retardant coating meets the requirements of GB / T14907-2018 "Fire Retardant Coatings for Steel Structures".

[0055] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An intumescent fire retardant coating based on solid waste from sewage treatment, characterized in that: The intumescent fire retardant coating comprises the following raw materials in parts by weight:

2. The intumescent fire retardant coating according to claim 1, characterized in that: The struvite is solid waste generated when ammonia nitrogen and phosphorus are recovered from sewage by a struvite precipitation method.

3. The intumescent fire retardant coating according to claim 1, characterized in that: The film-forming emulsion is one or more of Wacker EP-707K emulsion, Badford 6067 emulsion, Polycar BLJ-8439 emulsion, Celanese LDM2301 emulsion, and Clariant DM230 emulsion.

4. The intumescent fire retardant coating according to claim 1, characterized in that: The pigment and filler is one or more of titanium dioxide, basic calcium carbonate, talcum powder and magnesium phosphate.

5. The intumescent fire retardant coating according to claim 1, characterized in that: The intumescent flame retardant is one or more of ammonium polyphosphate, melamine, melamine pyrophosphate, melamine phosphate, melamine polyphosphate, diammonium hydrogen phosphate, diammonium phosphate, and ammonium pyrophosphate.

6. The intumescent fire retardant coating according to claim 5, characterized in that: The ammonium polyphosphate is type II ammonium polyphosphate, and the degree of polymerization n is ≥1000.

7. The intumescent fire retardant coating according to claim 1, characterized in that: The plasticizer is pentaerythritol.

8. The intumescent fire retardant coating according to claim 1, characterized in that: The auxiliary agent includes one or more of a defoamer, a dispersant, a thickener, and an anti-flash rust agent.

9. The method for preparing an intumescent fire retardant coating according to any one of claims 1 to 8, characterized in that: The struvite, film-forming emulsion, pigments and fillers, intumescent flame retardants, plasticizers, additives and water are uniformly mixed according to the proportions to obtain the fire retardant coating.

10. Use of the intumescent fire retardant coating according to any one of claims 1 to 8 or the intumescent fire retardant coating prepared by the preparation method according to claim 9 in steel structures.

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