Aqueous fireproofing coating for steel structure and preparation method thereof

Abstract

The present application relates to a kind of water-based steel structure fire-retardant coating and its preparation method, belong to fire-retardant coating technical field;The present application is modified by phenylpropyl emulsion, modifier containing phosphate group is introduced into phenylpropyl emulsion by the way of copolymerization, phosphate group can produce phosphoric acid after thermal decomposition and promote carbonization to play the role of acid source, reduce the demand amount of external acid source ammonium polyphosphate, then weaken the ion strength of system as a whole, reduce the risk of demulsification, in addition, the present application also introduces furan ring structure with conjugated diene structure in phenylpropyl emulsion, can occur Diels-Alder reaction with acryloyloxy in silicon-acrylic emulsion with dienophile structure, can effectively improve the compatibility between phenylpropyl emulsion and silicon-acrylic emulsion, then improve the mechanical properties of fire-retardant coating as a whole.

Description

Technical Field

[0001] This invention belongs to the field of fire-retardant coating technology, specifically, it relates to a water-based fire-retardant coating for steel structures and its preparation method. Background Technology

[0002] Steel structures are widely used in industrial plants, large stadiums, bridges, and other fields due to their advantages such as high mechanical strength, light weight, strong earthquake resistance, and fast construction speed. However, steel structures have extremely poor fire resistance. As the temperature rises, the mechanical properties of steel structures will rapidly decline, eventually leading to loss of load-bearing capacity and building collapse. Therefore, effective fire protection for steel structures to ensure their stability for a certain period of time during a fire is a core requirement in the field of building safety. Water-based fire-retardant coatings for steel structures, as an efficient and widely used fire protection method, have emerged and continued to develop in this context.

[0003] Water-based fire-retardant coatings for steel structures use water as the dispersion medium. While this offers environmental advantages, its stability is far inferior to that of solvent-based fire-retardant coatings. Furthermore, due to the need to add a large amount of fire-retardant filler to the system, demulsification can easily occur when the hydrophilic fire-retardant filler and the hydrophobic emulsion base come into contact during mixing, leading to solution waste. To address these technical shortcomings, this invention modifies the emulsion base to reduce the amount of fire-retardant filler added while ensuring the fire resistance limit, thereby reducing the probability of demulsification. This invention provides a water-based fire-retardant coating for steel structures and its preparation method. Summary of the Invention

[0004] The purpose of this invention is to provide a water-based fireproof coating for steel structures and its preparation method, in order to solve the problems mentioned in the background art.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A method for preparing a water-based fire-retardant coating for steel structures includes the following steps:

[0007] S1. A flame retardant is obtained by esterification of methyl 3,4-dihydroxyphenylacetate with vinyl phosphoryl chloride.

[0008] S2. A modifier is obtained by reacting the flame retardant with furfural in a Krono Wenger reaction.

[0009] S3. A modified styrene-acrylic emulsion is obtained by copolymerization using styrene, butyl acrylate, methyl methacrylate, and a modifier as monomers, deionized water as solvent, and adding emulsifiers and initiators.

[0010] S4. Mix deionized water, dispersant, first batch of defoamer, and pigment evenly and grind to obtain a homogeneous slurry. Add fireproof filler to the homogeneous slurry and mix evenly again. Then add silicone acrylic emulsion and modified styrene acrylic emulsion to the system in batches while stirring continuously. After the addition is complete, add film-forming aid and second batch of defoamer to the system. Finally, adjust the pH of the system to 8-9 with pH adjuster. After filtration and curing, obtain water-based fireproof coating for steel structures.

[0011] As a further preferred embodiment of the present invention, the emulsifier is OP-10 and the initiator is ammonium persulfate.

[0012] As a further preferred embodiment of the present invention, the dispersant is one of BYK 190 and DIGIC 755W, the defoamer is one of HY-156 and HY-158, and the pigment is titanium dioxide.

[0013] As a further preferred embodiment of the present invention, the fire-retardant filler is composed of ammonium polyphosphate, pentaerythritol, and melamine in a mass ratio of 2:1:2.

[0014] As a further preferred embodiment of the present invention, the film-forming aid is Texanol, and the pH adjuster is AMP-95.

[0015] As a further preferred embodiment of the present invention, the organosilicon monomer in the silicone-acrylic emulsion is γ-methacryloyloxypropyltrimethoxysilane.

[0016] As a further preferred embodiment of the present invention, the stirring speed is 600-800 rpm.

[0017] As a further preferred embodiment of the present invention, the mass ratio of styrene, butyl acrylate, methyl methacrylate, modifier, deionized water, emulsifier and initiator used in S3 is 10-12:10-12:2-3:2-3:24-30:0.6-0.8:0.2-0.25.

[0018] As a further preferred embodiment of the present invention, the mass ratio of deionized water, dispersant, first batch defoamer, pigment, fire-retardant filler, silicone-acrylic emulsion, modified styrene-acrylic emulsion, film-forming aid, and second batch defoamer used in S4 is 20-30: 0.3-0.5: 0.15-0.25: 3-4: 18-22: 10-12: 18-20: 0.8-1.2: 0.15-0.25.

[0019] A water-based fire-retardant coating for steel structures is prepared by any of the above preparation steps.

[0020] This invention has at least one of the following beneficial effects:

[0021] This invention uses a compound system of styrene-acrylic emulsion and silicone-acrylic emulsion as the emulsion base material. During combustion, the styrene-acrylic emulsion decomposes and carbonizes to provide gas and carbon sources, forming a porous and thick expanded carbon layer. Meanwhile, the decomposition products of the silicone-acrylic emulsion can further strengthen the carbon layer skeleton, making the carbon layer more robust, dense, and resistant to ablation. The synergistic effect of the two can significantly improve the fire resistance limit of the fire-retardant coating.

[0022] The risk of demulsification during the preparation of water-based fire-retardant coatings for steel structures mainly stems from the acid source ammonium polyphosphate in the fire-retardant filler. Since ammonium polyphosphate ionizes in the aqueous phase, it significantly increases the ionic strength of the aqueous phase. This high ionic strength environment weakens the electrostatic repulsion between emulsion particles, making them more prone to coalescence upon collision, ultimately leading to demulsification. To address this issue, this invention modifies the styrene-acrylic emulsion by introducing a modifier containing phosphate ester groups into the emulsion via copolymerization. The phosphate ester groups, upon thermal decomposition, generate phosphoric acid, promoting char formation and acting as an acid source. This reduces the demand for the external acid source, ammonium polyphosphate, thereby weakening the overall ionic strength of the system and reducing the risk of demulsification.

[0023] This invention modifies styrene-acrylic emulsions by introducing a furan ring structure with a conjugated diene structure into the styrene-acrylic emulsion. This furan ring structure can undergo a Diels-Alder reaction with the acryloyloxy group with a diene-philic structure in the silicone-acrylic emulsion. This effectively improves the compatibility between the styrene-acrylic and silicone-acrylic emulsions, increases the crosslinking density between the emulsions, and thus enhances the mechanical properties and water resistance of the water-based fire-retardant coating after curing, as well as the strength and integrity of the expanded char layer formed after combustion. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments in this application specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection claimed in this application.

[0025] In the following embodiments, unless otherwise specified, all raw materials used are ordinary commercially available products that can be purchased directly or can be prepared using conventional methods in the art.

[0026] Example 1

[0027] A method for preparing a water-based fire-retardant coating for steel structures includes the following steps:

[0028] S1. By mass, 2.72 parts of methyl 3,4-dihydroxyphenylacetate, 2.18 parts of vinyl phosphoryl chloride, 0.1 parts of aluminum chloride, and 6 parts of tetrahydrofuran were mixed in a three-necked flask equipped with a reflux condenser and a thermometer. The mixture was reacted at 50°C for 6 hours. After the reaction was completed, the reaction solution was cooled and poured into deionized water. The solution was extracted with dichloromethane and the solvent was removed by rotary evaporation to obtain the flame retardant.

[0029] S2. By mass, 2.54 parts of flame retardant, 0.96 parts of furfural, 0.14 parts of piperidine, and 5 parts of tetrahydrofuran are mixed in a three-necked flask equipped with a reflux condenser and a thermometer. The mixture is reacted at 45°C for 3 hours. After the reaction is completed, the solvent is removed by rotary evaporation to obtain the modifier.

[0030] S3. By mass, mix 16 parts deionized water, 0.6 parts OP-10, 10 parts styrene, 10 parts butyl acrylate, 2 parts methyl methacrylate, and 2 parts modifier to obtain a pre-emulsion for later use. Then, mix 3.8 parts deionized water and 0.2 parts ammonium persulfate to obtain an initiator solution for later use. Next, add 4.2 parts deionized water and 0.1 parts sodium bicarbonate to the reaction vessel as a buffer solution. Then, add 4 parts pre-emulsion and 1.3 parts initiator solution. Heat to 80°C until the solution turns light blue. Then, keep the temperature constant and continuously add the remaining pre-emulsion and initiator solution dropwise to the system. After the addition is complete, keep the system at the temperature for aging. Then, adjust the pH of the system to 7.5 to obtain a modified styrene-acrylic emulsion.

[0031] S4. By mass, 20 parts deionized water, 0.3 parts BYK 190, 0.15 parts HY-156, and 3 parts titanium dioxide are mixed evenly and ground to obtain a homogeneous slurry. 18 parts fire-retardant filler are added to the homogeneous slurry and mixed evenly again. Then, 10 parts silicone-acrylic emulsion and 18 parts modified styrene-acrylic emulsion are added to the system in batches, while maintaining a stirring speed of 600 rpm. After the addition is complete, 0.8 parts Texanol and 0.15 parts HY-156 are added to the system. Finally, the pH of the system is adjusted to 8 with AMP-95. After filtration and aging, a water-based fire-retardant coating for steel structures is obtained.

[0032] In this embodiment, the organosilicon monomer in the silicone-acrylic emulsion is γ-methacryloyloxypropyltrimethoxysilane;

[0033] The fire-retardant filler is composed of ammonium polyphosphate, pentaerythritol, and melamine in a mass ratio of 2:1:2.

[0034] A water-based fire-retardant coating for steel structures, prepared by the above method.

[0035] Example 2

[0036] A method for preparing a water-based fire-retardant coating for steel structures includes the following steps:

[0037] S1. By mass, 4.09 parts of methyl 3,4-dihydroxyphenylacetate, 2.72 parts of vinylphosphoryl chloride, 0.125 parts of aluminum chloride, and 9 parts of tetrahydrofuran were mixed in a three-necked flask equipped with a reflux condenser and a thermometer. The mixture was reacted at 55°C for 5 hours. After the reaction was completed, the reaction solution was cooled and poured into deionized water. The solution was extracted with dichloromethane and the solvent was removed by rotary evaporation to obtain the flame retardant.

[0038] S2. By mass, 3.81 parts of flame retardant, 1.84 parts of furfural, 0.21 parts of piperidine, and 7.5 parts of tetrahydrofuran are mixed in a three-necked flask equipped with a reflux condenser and a thermometer. The mixture is reacted at 50°C for 2.5 hours. After the reaction is completed, the solvent is removed by rotary evaporation to obtain the modifier.

[0039] S3. By mass, mix 18 parts deionized water, 0.7 parts OP-10, 11 parts styrene, 11 parts butyl acrylate, 2.5 parts methyl methacrylate, and 2.5 parts modifier to obtain a pre-emulsion for later use. Then, mix 4.275 parts deionized water and 0.225 parts ammonium persulfate to obtain an initiator solution for later use. Next, add 4.725 parts deionized water and 0.15 parts sodium bicarbonate to the reaction vessel as a buffer solution. Then, add 4.5 parts pre-emulsion and 1.45 parts initiator solution. Heat to 80°C until the solution turns light blue. Then, keep the temperature constant and continuously add the remaining pre-emulsion and initiator solution dropwise to the system. After the addition is complete, keep the system at the temperature for aging. Then, adjust the pH of the system to 8 to obtain a modified styrene-acrylic emulsion.

[0040] S4. By mass, 25 parts deionized water, 0.4 parts TEG 755W, 0.2 parts HY-158, and 3.5 parts titanium dioxide are mixed evenly and ground to obtain a homogeneous slurry. 20 parts fire-retardant filler are added to the homogeneous slurry and mixed evenly again. Then, 11 parts silicone-acrylic emulsion and 20 parts modified styrene-acrylic emulsion are added to the system in batches, while maintaining a stirring speed of 700 rpm. After the addition is complete, 1 part Texanol and 0.2 parts HY-158 are added to the system. Finally, the pH of the system is adjusted to 8.5 with AMP-95. After filtration and curing, a water-based fire-retardant coating for steel structures is obtained.

[0041] In this embodiment, the organosilicon monomer in the silicone-acrylic emulsion is γ-methacryloyloxypropyltrimethoxysilane;

[0042] The fire-retardant filler is composed of ammonium polyphosphate, pentaerythritol, and melamine in a mass ratio of 2:1:2.

[0043] A water-based fire-retardant coating for steel structures, prepared by the above method.

[0044] Example 3

[0045] A method for preparing a water-based fire-retardant coating for steel structures includes the following steps:

[0046] S1. By mass, 5.46 parts of methyl 3,4-dihydroxyphenylacetate, 3.26 parts of vinyl phosphoryl chloride, 0.15 parts of aluminum chloride, and 12 parts of tetrahydrofuran were mixed in a three-necked flask equipped with a reflux condenser and a thermometer. The mixture was reacted at 60°C for 4 hours. After the reaction was completed, the reaction solution was cooled and poured into deionized water. The solution was extracted with dichloromethane and the solvent was removed by rotary evaporation to obtain the flame retardant.

[0047] S2. By mass, 5.08 parts of flame retardant, 1.92 parts of furfural, 0.28 parts of piperidine, and 10 parts of tetrahydrofuran are mixed in a three-necked flask equipped with a reflux condenser and a thermometer. The mixture is reacted at 55°C for 2 hours. After the reaction is completed, the solvent is removed by rotary evaporation to obtain the modifier.

[0048] S3. By mass, mix 20 parts deionized water, 0.8 parts OP-10, 12 parts styrene, 12 parts butyl acrylate, 3 parts methyl methacrylate, and 3 parts modifier to obtain a pre-emulsion for later use. Then, mix 4.75 parts deionized water and 0.25 parts ammonium persulfate to obtain an initiator solution for later use. Next, add 5.25 parts deionized water and 0.2 parts sodium bicarbonate to the reaction vessel as a buffer solution. Then, add 5 parts pre-emulsion and 1.6 parts initiator solution. Heat to 80°C until the solution turns light blue. Then, keep the temperature constant and continuously add the remaining pre-emulsion and initiator solution dropwise to the system. After the addition is complete, keep the system at the temperature for aging. Then, adjust the pH of the system to 8.5 to obtain the modified styrene-acrylic emulsion.

[0049] S4. By mass, mix 30 parts deionized water, 0.5 parts BYK 190, 0.25 parts HY-158, and 4 parts titanium dioxide evenly and grind them to obtain a homogeneous slurry. Add 22 parts fire-retardant filler to the homogeneous slurry and mix evenly again. Then, add 12 parts silicone-acrylic emulsion and 22 parts modified styrene-acrylic emulsion to the system in batches, while maintaining a stirring speed of 800 rpm. After the addition is complete, add 1.2 parts Texanol and 0.15-0.25 parts HY-158 to the system. Finally, adjust the pH of the system to 9 with AMP-95, filter and mature to obtain a water-based fire-retardant coating for steel structures.

[0050] In this embodiment, the organosilicon monomer in the silicone-acrylic emulsion is γ-methacryloyloxypropyltrimethoxysilane;

[0051] The fire-retardant filler is composed of ammonium polyphosphate, pentaerythritol, and melamine in a mass ratio of 2:1:2.

[0052] A water-based fire-retardant coating for steel structures, prepared by the above method.

[0053] Comparative Example 1

[0054] The difference between this comparative example and Example 1 is that no modifier is prepared, and no modifier is added in S3. The other raw materials and preparation steps remain unchanged, and the coating is eventually demulsified and scrapped.

[0055] Comparative Example 2

[0056] The difference between this comparative example and Comparative Example 1 is that the stirring speed during the preparation of the water-based fireproof coating for steel structures was reduced from 600 rpm to 300 rpm.

[0057] Experimental Example 1

[0058] Performance tests were conducted on the water-based fire-retardant coatings for steel structures in Examples 1-3 and Comparative Example 2. The fire resistance limit and water resistance of each component of the fire-retardant coating were tested according to the test methods described in GB14907-2018 "Fire-retardant Coatings for Steel Structures". The adhesion grade of each component of the fire-retardant coating was tested according to the test methods in GB / T 1720-1979 "Determination of Adhesion of Coating Films". The impact strength of each component of the fire-retardant coating was tested according to the test methods in GB / T 1732-2020 "Determination of Impact Resistance of Coating Films". The test results are shown in Table 1.

[0059] Table 1

[0060]

[0061] As can be seen from Table 1, under the premise of adding an equal amount of fire-retardant filler, the fire-retardant coating systems in Examples 1 to 3 are more stable, effectively reducing the risk of demulsification under high stirring speed, and the finished products have a longer fire resistance limit, as well as better water resistance and mechanical properties.

[0062] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0063] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing an aqueous fire-retardant coating for steel structures, characterized by, The preparation method comprises the following steps: S1, methyl 3,4-dihydroxyphenylacetate is subjected to esterification with vinyl phosphorus oxychloride to obtain a flame retardant; S2, the flame retardant is subjected to a Grignard reaction with furfural to obtain a modifier; S3, styrene, butyl acrylate, methyl methacrylate, the modifier are used as polymerization monomers, deionized water is used as a solvent, and an emulsifier and an initiator are added to copolymerize to obtain a modified styrene-acrylic emulsion; S4, deionized water, a dispersing agent, a first batch of defoaming agent, and pigments are uniformly mixed and ground to obtain a homogeneous slurry, a fireproof filler is added to the homogeneous slurry and uniformly mixed again, then a silicone-acrylic emulsion and the modified styrene-acrylic emulsion are added to the system in batches, stirring is continuously performed during the addition, after the addition is completed, a film-forming aid and a second batch of defoaming agent are added to the system, finally, a pH regulator is used to adjust the pH of the system to 8-9, and after filtration and aging, a water-based steel structure fireproof coating is obtained.

2. The method for preparing a water-based fire-retardant coating for steel structure according to claim 1, characterized in that, The emulsifier is OP-10, and the initiator is ammonium persulfate.

3. The method for preparing a water-based fire-retardant coating for steel structure according to claim 1, characterized in that, The dispersing agent is one of BIC 190 and DEGOW 755W, the defoaming agent is one of HY-156 and HY-158, and the pigment is titanium dioxide.

4. The method for preparing a water-based fire-retardant coating for steel structures according to claim 1, characterized in that, The fireproof filler is obtained by mixing ammonium polyphosphate, pentaerythritol and melamine at a mass ratio of 2:1:

2.

5. The method for preparing a water-based fire-retardant coating for steel structures according to claim 1, characterized in that, The film-forming aid is Texanol, and the pH regulator is AMP-95.

6. The method for preparing a water-based fire-retardant coating for steel structures according to claim 1, characterized in that, The organic silicon monomer in the silicone-acrylic emulsion is γ-methacryloyloxypropyl trimethoxysilane.

7. The method for preparing a water-based fire-retardant coating for steel structures according to claim 1, characterized in that, The rotation speed of the stirring is 600-800 rpm.

8. The method for preparing a water-based fire-retardant coating for steel structures according to claim 1, characterized in that, The mass ratio of styrene, butyl acrylate, methyl methacrylate, the modifier, deionized water, the emulsifier, and the initiator used in S3 is 10-12:10-12:2-3:2-3:24-30:0.6-0.8:0.2-0.

25.

9. The method for preparing a water-based fire-retardant coating for steel structures according to claim 1, characterized in that, The mass ratio of deionized water, the dispersing agent, the first batch of defoaming agent, the pigment, the fireproof filler, the silicone-acrylic emulsion, the modified styrene-acrylic emulsion, the film-forming aid, and the second batch of defoaming agent used in S4 is 20-30:0.3-0.5:0.15-0.25:3-4:18-22:10-12:18-20:0.8-1.2:0.15-0.

25.

10. An aqueous fire-retardant coating for steel structures, characterized in that, The water-based steel structure fireproof coating is prepared by the preparation method in any one of the above claims 1-9. The preparation method comprises the following steps: S1, methyl 3,4-dihydroxyphenylacetate is subjected to esterification with vinyl phosphorus oxychloride to obtain a flame retardant; S2, the flame retardant is subjected to a Grignard reaction with furfural to obtain a modifier; S3, styrene, butyl acrylate, methyl methacrylate, the modifier are used as polymerization monomers, deionized water is used as a solvent, and an emulsifier and an initiator are added to copolymerize to obtain a modified styrene-acrylic emulsion; S4, deionized water, a dispersing agent, a first batch of defoaming agent, and pigments are uniformly mixed and ground to obtain a homogeneous slurry, a fireproof filler is added to the homogeneous slurry and uniformly mixed again, then a silicone-acrylic emulsion and the modified styrene-acrylic emulsion are added to the system in batches, stirring is continuously performed during the addition, after the addition is completed, a film-forming aid and a second batch of defoaming agent are added to the system, finally, a pH regulator is used to adjust the pH of the system to 8-9, and after filtration and aging, a water-based steel structure fireproof coating is obtained. The emulsifier is OP-10, and the initiator is ammonium persulfate. The dispersing agent is one of BIC 190 and DEGOW 755W, the defoaming agent is one of HY-156 and HY-158, and the pigment is titanium dioxide. The fireproof filler is obtained by mixing ammonium polyphosphate, pentaerythritol and melamine at a mass ratio of 2:1:

2. The film-forming aid is Texanol, and the pH regulator is AMP-95. The organic silicon monomer in the silicone-acrylic emulsion is γ-methacryloyloxypropyl trimethoxysilane. The rotation speed of the stirring is 600-800 rpm. The mass ratio of styrene, butyl acrylate, methyl methacrylate, the modifier, deionized water, the emulsifier, and the initiator used in S3 is 10-12:10-12:2-3:2-3:24-30:0.6-0.8:0.2-0.

25. The mass ratio of deionized water, the dispersing agent, the first batch of defoaming agent, the pigment, the fireproof filler, the silicone-acrylic emulsion, the modified styrene-acrylic emulsion, the film-forming aid, and the second batch of defoaming agent used in S4 is 20-30:0.3-0.5:0.15-0.25:3-4:18-22:10-12:18-20:0.8-1.2:0.15-0.

25. The water-based steel structure fireproof coating is prepared by the preparation method in any one of the above claims 1-9.

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